信息编号11325801至11325850间共50条。
☉ 11325801:The Calling
I grew up in Africa, the younger of two sons of Indian parents who taught college physics. Around the time that my brother's precocious ability with numbers was revealing itself, I discovered that I had no head for math — or for any other subject in the school curriculum. Middle-class Indian parents worshipped the professions, and only three existed for them: medicine, engineering, and law. When my brother announced, while still in short pants, that he was going to be an engineer, my parents' joy was astonishing to behold. Nothing I had ever said had produced such a reaction. I promptly proclaimed that I intended to be a doctor. What made this remotely plausible, even to me, was that I had more than a passing familiarity with blood, mostly my own, because I was always getting into scrapes. Moreover, my unseemly interest in witnessing chicken and sheep being slaughtered for the kitchen and my fascination with watching animals give birth could now be viewed as a form of scholarship. Having announced this bogus call to medicine so early in life, I did not give it another thought. Which is why when the true call to medicine arrived when I was 12 years old, I was flabbergasted. The moment did not have the high drama of Saint Paul's revelation on the road to Damascus. My call came quietly, but there was no mistaking it. It came in the form of a book. I loved to read and did so with little discrimination and with a prejudice toward works that I thought might be titillating. I picked up Of Human Bondage by Somerset Maugham because the title was promising, and I had already read Lolita and Lady Chatterley's Lover. Of course, the book was nothing like what the title had suggested to me; it was better. The opening scene — in which Philip, a club-footed child, is ushered to his mother's deathbed to say goodbye — still haunts me. Orphaned and raised by stern relatives, and taunted in school because of his clubfoot, Philip finds solace in painting. After high school, he sets off to Paris to become an artist. Money is tight, and he lives on the brink of starvation. One day, he persuades his art teacher, Monsieur Foinet, to assess his paintings and tell him whether he should continue. The teacher studies Philip's work and makes a brilliant speech about money and its connection to the arts: "Money is like a sixth sense without which you cannot make a complete use of the other five. . . . I pity with all my heart the artist, whether he writes or paints, who is entirely dependent for subsistence upon his art." As to his opinion on Philip's art, he offers this: "take your courage in both hands and try your luck at something else."1 Philip, crushed and disappointed but also relieved to have discovered what is not to be his calling, returns to London and enters medical school. The learning is grueling, and the life hard. But when he enters the outpatient clinic, he realizes he has made the right choice: He found the work of absorbing interest. There was humanity there in the rough, the materials the artist worked on; and Philip felt a curious thrill when it occurred to him that he was in the position of the artist and the patients were like clay in his hands. . . . Philip found that he was less shy with these people than he had ever been with others; he felt not exactly sympathy, for sympathy suggests condescension; but he felt at home with them. He found that he was able to put them at their ease, and, when he had been given a case to find out what he could about it, it seemed to him that the patient delivered himself into his hands with a peculiar confidence. "Perhaps," he thought to himself, with a smile, "perhaps I'm cut out to be a doctor. It would be rather a lark if I'd hit upon the one thing I'm fit for."1 The phrase "humanity there in the rough" spoke directly to my 12-year-old mind. I took it to mean that even if one did not have the talent to be an artist (or mathematician), one could aspire to be a doctor, perhaps even a good one; medicine was proletarian, and the prime prerequisite was to have an interest in humanity in the rough. I could not tell my family how much Of Human Bondage had affected me or that I had now found my calling, because they believed I already had. And I was also learning, from books, that grand outward pronouncements of passion were not as significant as quiet inner convictions. Of Human Bondage reinforced another lesson, that good literature, particularly fiction, has the power to transform. A good book can give the reader insight into his or her own life and may reveal its purpose. Soon after this experience, another book affirmed my choice of career. A.J. Cronin, the author of The Citadel (1938), was, like Somerset Maugham, a physician, although he eventually gave up medicine to write novels. The Citadel traces the career of the doctor Andrew Manson from his idealistic youth, through his succumbing to temptation in a high-society practice, to his reclaiming of his true values — a triumph that, tragically, coincides with the sudden death of his dear wife. An immensely popular writer, Cronin was ostracized by his medical peers for his liberal views, but it is said that his books documenting the terrible state of medical care in England were instrumental in the later creation of the National Health Service. When I arrived in the United States as an intern in 1980, I diffidently mentioned to one of my attending physicians the two books that had brought me to medicine. He was unfamiliar with the particular books but not surprised by the phenomenon. He noted that Sinclair Lewis's Pulitzer Prize–winning 1926 novel, Arrowsmith, about a man torn between pure scientific inquiry and the exigencies of medical practice, and Paul de Kruif's Microbe Hunters had had a similar influence on young prospective physicians in this country. How and why do such books inspire young people at the threshold of their careers? The most obvious answer is that the protagonist in these novels is often wrestling with and finding his or her calling, and the reader (or perhaps a certain kind of reader) identifies with and is drawn to the character facing such a crisis. Such novels often celebrate the quietly heroic aspect of medicine, fashioning physicians in the mold of Joseph Campbell's archetypal hero — those who have dedicated their lives to something bigger than themselves. But a good novel can offer a formative experience to prospective doctors that is both broader and deeper than identification with an admirable or sympathetic hero, and I worry that today's students may be missing out. On the one hand, students seem to me to be coming to medical school with a greater number and diversity of talents than the students of a generation ago, not only playing myriad musical instruments but also pursuing athletic hobbies ranging from spelunking to pole vaulting. On the other hand, our entering classes don't seem to include as many avid readers as they once did. This may simply reflect a societal trend, but it is one that I, as an educator, cannot be complacent about. John Fowles talks about a "prevalent form of blindness, directly caused by the terrible and crippling atrophy of the imaginative faculty (being unable to slip down the magical passage from the little signals we call words into far richer worlds than any film or TV `version' will ever be able to present)."2 Indeed, watching films and television are passive activities; reading, by contrast, is dynamic and collaborative: the reader uses the writer's words to construct a rich fictional dream of his or her own. As readers, we enjoy this creative process best when the writer provides just enough, but not so much that our imagination has no work to do. Reading fiction is an easy skill, but it is also easy to avoid. The couch and the remote control beckon and compete. But the diagnosis Fowles outlines comes with an obvious prescription — a few hours spent with Gabriel Garcia Márquez's Love in the Time of Cholera will inoculate against cortical atrophy and preserve and expand the clinical imagination. The activity is just as salutary as a 20-minute run and easier on the knees. But there's more to it than that. As Joanne Trautmann says, "A fully imagined world is far richer than our own."3 A well-developed fiction-reading capacity allows us to imagine our patients' worlds fully and put ourselves in their shoes. I have marveled at the way in which selected fiction discussed in a medical school class effectively conveys the tenets of professionalism and multiculturalism without ever invoking those soporific words. "Fiction," says the writer Dorothy Allison, "is the great lie that tells the truth as to how the rest of the world lives."4 In this visual and cyber age, when the death of the novel has been predicted for decades, one must wonder where medical students of future generations will find their Arrowsmiths, their Citadels, their Of Human Bondages. Where will their sense of calling come from? From television shows like ER and Scrubs? The thought is chilling. Perhaps the whole idea of a calling is old-fashioned anyway. The sheer volume of information that today's medical students must assimilate, the debt most have to take on, and the increasingly technological nature of medicine surely dampen the sense of calling. By the end of their studies, students are often less idealistic and more pragmatic than when they began. The pressures of managed care, the malpractice crisis, and rising health care costs loom in their future. And yet students continue to enroll in medical school, coming to the profession for timeless reasons — because of a physician they admire, or because they want to serve, or because they have suffered or witnessed suffering. Perhaps some lucky ones even today have been called to medicine through the medium of a book. If they have a love of literature, reading may well help them to discover a way to understand and identify with the ambitions, sorrows, and joys of the people whose lives are put in their hands. In medicine, we often separate life events from their meaning for those who live them. In literature, the two are united. That is reason enough to keep reading. And writing. Source Information Dr. Verghese is a professor of medicine and director of the Center for Medical Humanities and Ethics, University of Texas Health Sciences Center, San Antonio. References Maugham WS. Of human bondage. New York: Bantam Books, 1991. Fraser A, ed. The pleasure of reading. London: Bloomsbury, 1992:74-8. Trautmann J. The wonders of literature in medical education. Mobius 1982;2:23-31. Allison D. Skin: talking about sex, class & literature. Ithaca, N.Y.: Firebrand Books, 1994....查看详细 (10853字节)

☉ 11325802:Physician as Serial Killer — The Shipman Case
When a doctor does go wrong he is the first of criminals. He has nerve and he has knowledge. Sir Arthur Conan Doyle, "The Speckled Band" Harold Fredrick Shipman, a British general practitioner, was convicted on January 31, 2000, of murdering 15 of his patients (and of forging a will of one of them) while he was practicing in a small town in northwest England. He had killed these patients by administering lethal doses of diamorphine (diacetylmorphine). He was sentenced to 15 concurrent terms of life imprisonment but committed suicide while in custody on January 13, 2004. His conviction raised so many important issues that a public inquiry was initiated in February 2001. It was chaired by a senior high-court judge, Dame Janet Smith, and I was appointed her medical advisor. The inquiry investigated the number of deaths for which Shipman may have been responsible during his career, from August 1970 to July 1998. After investigating more than 1000 deaths that he had certified, in what must be the largest forensic investigation ever conducted in the United Kingdom, Smith reached a verdict of unlawful killing in 218 cases. She had serious suspicions that he might have been involved in the deaths of 62 other patients, but she did not have sufficient evidence to reach a decision on those. This record makes Shipman the most prolific serial killer in the history of the United Kingdom — and probably the world. Of the 218 known victims, 171 were women and 47 were men. Shipman's typical victim was an elderly person living alone. His oldest victim was 93 years of age; his youngest was only 41. Most of Shipman's victims were not terminally ill and did not have any immediately life-threatening condition; their deaths were generally unexpected. Many of the killings followed a pattern. Shipman would visit an elderly patient, usually one who lived alone. Sometimes the visit would be at the patient's request, on account of an ailment; sometimes Shipman would make a routine visit, to take a blood sample, for instance, or to provide a prescription; sometimes he would make an unsolicited call. During the visit, Shipman would kill the patient by administering a lethal injection of diamorphine or morphine. Inevitably, there has been much speculation about Shipman's motives. What kind of person works hard to become a doctor, takes the Hippocratic oath, and within a few years embarks on a career of killing his or her patients? After his arrest and questioning, Shipman refused to speak to anyone and continued to deny responsibility for the deaths. There is therefore no complete psychological or psychiatric assessment available and no useful information regarding his family background or relationships. The only evidence that the inquiry obtained was the videotape of his questioning by the police, the prison and medical reports, and the evidence from his trial. The inquiry sought the views of a panel of eminent forensic psychiatrists who were given access to this material and to psychiatric reports that had been written after his conviction for abusing pethidine (meperidine) in 1976. Unfortunately, the available material did not provide any insight into Shipman's motivation or his character. If one defines motive as the rational or conscious explanation for the decision to commit a crime, then Shipman's crimes were without motive. His mother had died of cancer when he was in late adolescence, and this experience may have motivated him to go into medicine. Early in his career, he became addicted to pethidine, and the psychiatric reports suggested that he was depressed. It is quite possible that whatever problem drove him to addiction was never resolved and that the drug addiction was just one manifestation of an addictive personality. If so, he may have become addicted to killing, experiencing a "buzz" of pleasure from the association with death and the power and control that it gave him. Shipman was respected by both his patients and fellow health care professionals and was a hugely popular doctor in his community, but he had very few friends and was quite isolated professionally. His early victims were terminally ill or in very poor health. There was very little risk that giving an opiate to a patient whose death was expected would arouse suspicion or lead to detection. The killings of such people might have seemed to Shipman to be the least morally culpable. He may have tried to justify them in his own mind, but he was clearly killing in response to a need of his own and selected victims primarily so as to avoid discovery. It is impossible to consider Shipman's crimes without considering the context in which he killed and remained unsuspected for so long. After examining evidence for four years at a cost of nearly ￡21 million ($40.4 million), the inquiry issued numerous recommendations. These covered the system of death certification, the investigation of deaths by coroners, the regulation of controlled drugs in the community, and most recently, the monitoring and regulation of the work of general practitioners. The inquiry found fundamental weaknesses in the existing systems that enabled Shipman to kill and not be discovered for many years. He was able to amass large quantities of diamorphine, notwithstanding regulations designed to prevent such stockpiling. He was able to certify a cause of death of patients whom he had killed and to thus avoid reporting the deaths to the coroner. There was no effective check on the information that he recorded on cremation certificates. There was no system for monitoring the number of death certificates signed by a given doctor, so no one noticed the large number signed by Shipman. Faced with the revelations about Shipman, many doctors in the United Kingdom argued that there is no need for systemic reform because there will never be another Shipman. A common refrain was that Shipman was a killer who just happened to be a doctor. I take the view that it was the very fact that Shipman was a doctor that enabled him to kill and remain undiscovered. His profession provided him with the opportunity to kill, and the lack of safeguards and controls allowed him to avoid suspicion. Society invests great trust in doctors, giving us immense power. Shipman abused that trust, thereby exposing the profession's power and patients' lack thereof. In considering the role of trust and accountability in doctor–patient relationships, regulators and professional organizations must aim to equalize the power imbalance. Some of the best safeguards against another Shipman include encouraging a more questioning attitude toward doctors and implementing better systems for monitoring their work, especially their care of the most vulnerable patients. If this means greater regulation of the medical profession, then that may well be something we have to take on board. That is the real lesson of the case of Harold Shipman. Source Information Dr. Esmail is a professor of general practice in the Division of Primary Care, University of Manchester, Manchester, United Kingdom....查看详细 (7156字节)
☉ 11325803:Antibiotic Optimization: Concepts and Strategies In Clinical Practice
During the past decade, there has been a substantial rise in the number of antibiotic-resistant infectious organisms. Antimicrobial resistance is important because of its effect on the success and cost of antimicrobial treatment and on the treatment of patients in both the hospital and the community. There are few new antimicrobial compounds on the horizon, because many major pharmaceutical companies are no longer involved in the discovery of antimicrobial drugs. To that end, the principles of and programs for reducing the spread of resistant pathogens and of optimizing the efficacy of currently available antimicrobial agents are of interest to many clinicians. "Antimicrobial stewardship," a term coined by Dr. Dale Gerding, applies to the selection of an antimicrobial agent and its appropriate dosage and duration of therapy. In principle, this results in the best clinical outcome in the treatment or prevention of infection, with the least toxicity and, most important, a minimal effect on the development of resistance in the patient and in larger populations, whether in the hospital or the community. The goal of Antibiotic Optimization is to provide the practicing clinician and the interested administrator with the background, scientific foundation, and practical knowledge required to develop institutional programs that foster good antimicrobial stewardship. The book draws on many recommendations by professional societies and national and international organizations that have recognized the importance of antimicrobial stewardship as a mechanism to prevent antimicrobial resistance. The editors are to be congratulated for assembling an expert group of authors to write the 19 chapters that make up this treatise. The book has two main parts. The initial chapters provide an overview of topics that serve as the foundation of a successful program of antimicrobial stewardship, such as the importance of a pharmacy and therapeutics committee, a program for infection control and hospital epidemiology, and a basic understanding of pharmacoeconomics, pharmacokinetics, and pharmacodynamics. The remainder of the book deals with examples of the application of antimicrobial stewardship. These chapters provide insight into the importance of pharmacodynamic principles, transitional-therapy programs, and the development and implementation of an antimicrobial formulary. The chapters are very well referenced and understandable for readers without expert knowledge of the subject. In general, the references are to articles published up to 2003, with a few from 2004. The chapters that focus on the optimization of antibacterial therapy to maximize patient safety, the application of pharmacodynamics, and the importance of an antimicrobial formulary are especially well written. The examples of successfully implemented programs — for example, the use of continuous infusions of antimicrobial agents or the transition of antimicrobial therapy from a parenteral to an oral form — provide "real-life" methods of optimizing antimicrobial therapy. One criticism is the absence of a chapter on the role of the microbiology laboratory in the optimization of antibiotics. Appropriate testing and reporting are critical factors in the choice of an antimicrobial agent. In addition, some figures in the book are unreadable, and in the chapter on antimicrobial cycling, there is probably too much of the primary data without a countervailing discussion of the inconsistencies of the data in terms of efficacy. This subject is still being debated among most authorities. Despite these few deficiencies, this book is a good resource by which to ensure the appropriate use of antimicrobial therapy. Physicians already involved in antimicrobial-stewardship programs will not find much new information here, although the book will serve as a useful reference for them. It is written in a way that will appeal to a broad group of clinicians, pharmacists, nurses, researchers, hospital administrators, and policymakers. David R. Snydman, M.D. Kenneth R. Lawrence, Pharm.D. Tufts–New England Medical Center Boston, MA 02111 dsnydman@tufts-nemc.org...查看详细 (4212字节)

☉ 11325804:Tuberculosis and the Tubercle Bacillus
At the start of the 20th century, tuberculosis was the second leading cause of death in the United States. One hundred years later, it does not figure among the top 20 causes. Improvements in housing and sanitation, decreased crowding, and the introduction of a number of antituberculous drugs are responsible for that change. Worldwide, however, the story is different. Mycobacterium tuberculosis kills about 3 million people per year, vying with HIV as the single most deadly infectious agent. Add to this the worsening problem of multidrug-resistant mycobacteria, and the need for new therapeutic modalities is urgent. Fortunately, the advent of genomics, in which high-throughput, automated forms of technology determine the entire DNA sequence of an organism, provides an important new tool against tuberculosis. Knowing the entire genetic complement of an organism potentially allows us to scrutinize its complete metabolic blueprint and pathogenic mechanisms for vulnerabilities that could be exploited by new therapeutics. Molecules of the mycobacterium could also be identified for testing in subunit vaccines or other types of vaccines. That, at least, is the theory. In fact, the 4,411,529 base pairs of the tubercle bacillus require a formidable effort at decipherment before the bacillus will yield its secrets, and this large amount of new data must be unified with more traditional studies. To serve this need, the editors of Tuberculosis and the Tubercle Bacillus have produced a book of 37 chapters, broadly organized into three sections. The first covers the disease of tuberculosis and examines the epidemiology, clinical presentation, diagnosis, and multidrug-resistance mechanisms of the disease. The coverage is somewhat patchy; for example, the discussion of diagnosis focuses more on the methods suitable for epidemiologic and laboratory investigation of immune mechanisms than on routine hospital practice. Clinicians seeking detailed information on the presentation of the disease or its management should look elsewhere, because the focus of this book is the laboratory scientist. It is in the other two sections, which consist of descriptions of the molecular makeup of the bacterium and of host–pathogen interactions, that the book excels. Here readers will find comprehensive coverage of the information arising from genome, microarray, and proteomic studies. The description of the components of the cell wall, a fiendishly complex melding of diverse glycolipids, is very good. Various aspects of cellular metabolism, including those of iron handling, cell signaling, transport, and so on, all receive their due. Similarly, the interaction of the bacillus with the macrophage and the acquired immune system are all examined in detail and to telling effect. It would have been helpful to see less of the confusing conflation of data from animal models and human studies that the tuberculosis field seems to love, but the wealth of information gathered in this one book makes it indispensable. As in any multiauthored book, there is variation in writing style, depth, and quality among contributions, but overall the standard is extremely high. I could find no references more recent than 2003, but this is the nature of the beast, as every editor who has awaited that last laggard chapter and cursed its recalcitrant authors knows too well. This book should become the first choice for readers of a technical bent who wish to know where the study of tuberculosis stands in these first heady years after the advent of genomics. I strongly recommend it. Ross Coppel, Ph.D. Monash University Clayton, VIC 3800, Australia ross.coppel@med.monash.edu.au...查看详细 (3722字节)
☉ 11325805:When Germs Travel: Six Major Epidemics That Have Invaded America Since 1900 and the Fears They Have Unleashed
In Howard Markel's engaging book, the second word of the title is a good clue that the author writes for the general reader rather than for the specialist. The book contains an introduction and an epilogue, with each of the six intervening chapters devoted to an infectious-disease episode in the past century: tuberculosis, plague, trachoma, typhus, AIDS, and cholera (the last being the only case that proved to be a false alarm). Germs are nature's primordial terrorists. The language of terror we encounter in our daily news is everywhere in this book, beginning with the title: "invaded," "fears," "unleashed." Indeed, one of the accepted definitions of terror as "living in dread of death or outrage" conveys quite well how epidemics have been experienced throughout history and in the six cases presented in this book. Markel describes modes of transmission, incubation periods, clinical features, and common outcomes of infectious agents in lay terms, but it is the behavior of public officials, infected persons, and the public at large that proves to be the most interesting and disturbing. Each chapter tells its story by presenting accounts of people who bore the infection and of those who were in positions to respond to the outbreak. One of the perennial discouragements of public health workers is the predictability of such responses. We might forgive some of the foolish reactions early in the last century, when characteristics of infections, modes of transmission, and effective controls were little understood, but judging from our responses to more recent threats, we appear not to have learned much. Fear, irrational policy, and misdirected blame are still common. In the epilogue, titled "Public Health Is Purchasable," Markel admonishes the wealthy nations of the world to contribute toward a "cooperative partnership of nations, health care professionals, researchers, public health specialists, concerned corporations, philanthropies, and individuals . . . to safeguard the world against the many public health problems we face today." He gives little attention to the many such attempts that are already under way, however. For the general reader learning about these issues for the first time, perhaps the admonition alone is sufficient, but public health professionals will be disappointed by the lack of more detailed recommendations. Epidemiologists, public health officials, specialists in infectious disease, and most practicing physicians will find no new principles described here. Infectious agents are not new; epidemics are not new; the public and professional responses are not new; the observation that "germs" can travel fast is not new; and even the author's call for coordinated action and support from wealthy nations is not new. Nonetheless, the details of the six epidemics described in the book are fascinating, and the narrative is brisk and highly readable. No two "invasions" are the same, and the public health goals of avoiding overly restrictive measures during an epidemic while not ignoring the risks between epidemics need to be constantly reemphasized. Those who teach epidemiology and public health will find useful material, with excellent documentation and footnotes, to engage students. Reading When Germs Travel is a rewarding yet disturbing trip. Alfred O. Berg, M.D., M.P.H. University of Washington Seattle, WA 98195...查看详细 (3421字节)

☉ 11325806:Infections of Leisure
When I was asked to review this book, I was taken aback, since I truly didn't understand what "infections of leisure" are. The title, although playful, does not quite capture the scholarliness of this multiauthored book, which is published by the American Society for Microbiology. With long lists of references, it describes all the infectious diseases that can be contracted while pursuing such activities as gardening, lolling in a hot tub, eating trendy cuisines, swimming at the beach, or sharing abodes with pets. As an example of its seriousness, the chapter titled "At the Shore" has 491 references, with an exhaustive listing of vibrio infections that lurk at the seaside, as well as extensive discussions of shellfish intoxication and marine trauma. Potential zoonoses are charted in clever chapters, such as "With Man's Best Friend" (the dog), "Man's Worst Friend (the Rat)," and "Feathered Friends." Chapters are also devoted to infections contracted by such peculiar activities of leisure as body piercing, getting a tattoo, and taking a junket "From Boudoir to Bordello: Sexually Transmitted Diseases and Travel." Color-Enhanced Transmission Electron Micrograph of the Norovirus, Which Causes Acute Gastroenteritis. David Gregory and Debbie Marshall/Wellcome Photo Library. As with every book with many contributors, Infections of Leisure presents various editorial voices. The chapter on exotic and trendy cuisine is chatty and personal, whereas the one titled "Freshwater: From Lakes to Hot Tubs" is more formal. Some of the chapters appear to be slightly forced. Despite the fact that high-altitude trekking is a popular leisure activity, are there truly more infections at high altitudes than at low altitudes? The authors admit that since there are few published data on the topic, anecdotal and personal medical experiences are presented, rather than evidence-based studies. In summary, this is a thoroughly enjoyable book for general practitioners caring for patients who travel to exotic settings, eat adventuresome food, keep exotic pets, and pierce strange parts of their bodies. It will also appeal to the subspecialist in infectious diseases who is interested in an accessible organization of organisms associated with exposure to specific recreational activities. The next edition should sport a better title. Michele Barry, M.D. Yale University New Haven, CT 06443...查看详细 (2431字节)
☉ 11325807:The Cost of Institutional Review Boards in Academic Medical Centers
To the Editor: An important concern with respect to protecting human research participants is that institutional review boards (IRBs) have insufficient resources.1 However, there are few reports of the actual costs of IRB review.2,3,4 To estimate the cost of operating academic IRBs in 2002, we undertook a survey with the support of the Doris Duke Charitable Foundation and the Burroughs Wellcome Fund. We surveyed 121 U.S. medical schools with active IRBs; 63 representative institutions responded. Institutions documented the education, experience, and job titles of IRB staff; the composition of the IRB itself; the estimated amounts of time spent on various activities; the costs of equipment, supplies, travel, and space; and the use of outside services. Telephone interviews were then conducted. Activities were converted to costs with the use of nationally published wage rates, costs of office space, and other standardized cost figures. Low-volume institutions (those with fewer than 350 new protocols per year) had on average 6 IRB staff members, and high-volume institutions (with 700 or more new protocols per year) had 14. The mean number of IRB panels was 1.8 in low-volume institutions and 4.1 in high-volume institutions. Fifteen percent of institutions outsourced some portion of the reviews — ranging from 2 to 378 protocols annually; 41 percent of new protocols underwent expedited review. Forty-three percent of institutions provided no monetary payments to IRB members. On average, 29 percent of IRB staff time was spent on general administration, 27 percent on review and approval of protocols, 12 percent on monitoring of compliance, 11 percent on training, 9 percent on adverse-event reporting, 7 percent on compliance with the Health Insurance Portability and Accountability Act (HIPAA), and 5 percent on conflicts of interest. The time spent by IRB members on these activities was distributed in various ways. For instance, chairs and vice-chairs spent more than half their time on review and approval of protocols and less than 10 percent on each of the other activities. Estimates of costs are displayed in Table 1. Total cost was correlated with total protocol volume (=0.61, P<0.001) and with the number of new protocols (=0.52, P<0.001). Table 1. Estimated Median Costs of Institutional Review Boards at U.S. Medical Schools in 2002. The median amount spent by academic medical centers for the system of protecting human research participants is nearly $750,000 per year, exceeding previously reported estimates based on older data or single institutions.3,4,5 As previously reported, there are economies of scale in IRB activities5; a greater volume of reviews can be conducted at a lower cost per protocol reviewed. However, efforts to enhance efficiency need to be assessed critically. Expedited review is used quite frequently, but it costs about the same as full protocol review. Although there are sound pragmatic reasons for the expedited-review procedures outlined in federal regulations, the reasons for this finding are unclear. Expedited review may be conducted by the chair or other members of IRBs who incur a relatively large opportunity cost. Deliberations about the appropriate compensation of academic medical centers for IRB oversight should incorporate its true costs. Our data may be useful in preparing institutional budgets and securing adequate resources. Future research is needed to understand how these investments relate to the quality of IRB review and oversight and whether these investments are sufficient to meet the ethical goal of protecting participants in research with human subjects. Jeremy Sugarman, M.D., M.P.H. Johns Hopkins University Baltimore, MD 21205 Kenneth Getz, M.S., M.B.A. Tufts University Medford, MA 02111 Jeanne L. Speckman, M.Sc. Boston University Boston, MA 02118 Margaret M. Byrne, Ph.D. University of Miami Miami, FL 33136 Jason Gerson Johns Hopkins University Baltimore, MD 21205 Ezekiel J. Emanuel, M.D., Ph.D. National Institutes of Health Bethesda, MD 20892 for the Consortium to Evaluate Clinical Research Ethics References Department of Health and Human Services, Institutional review boards: a time for reform. Washington, D.C.: Office of Inspector General, 1998. (DHHS publication no. OEI-01-97-00193.) Institute of Medicine. Responsible research: a systems approach to protecting research participants. Washington, D.C.: National Academies Press, 2002. Brown JHU, Schoenfield LS, Allan PW. The costs of an institutional review board. J Med Educ 1979;54:294-299. Wagner TH, Bhandari A, Chadwick GL, Nelson DK. The cost of operating institutional review boards (IRBs). Acad Med 2003;78:638-644. Wagner TH, Cruz AME, Chadwick GL. Economies of scale in institutional review boards. Med Care 2004;42:817-823....查看详细 (4961字节)
☉ 11325808:Return of Renal Function after Endovascular Treatment of Aortic Dissection
To the Editor: We report a case of asymptomatic dissection of the descending aorta (type B aortic dissection) with silent renal hypoperfusion. A small, nonfunctioning kidney and a contralateral hypertrophied kidney were identified after symptomatic secondary extension of the aortic dissection occurred. After endovascular treatment, the reperfused kidney returned to a normal size and regained function, and the hypertrophy of the contralateral kidney regressed. A 44-year-old man was admitted to the hospital for type B aortic dissection. Computed tomographic (CT) scanning showed patency of the celiac, superior mesenteric, and right renal arteries, but hypoperfusion was present from dynamic compression of the true lumen by the false lumen.1 The left renal artery was involved in the dissection but was patent. The right kidney was atrophic (95.8 mm), and scintigraphic studies indicated that there was no function. The left kidney had undergone compensatory hypertrophy (142.5 mm) (Figure 1A). The patient had hypertension of recent onset, but he had not adhered to the recommended medical therapy. Figure 1. CT Scans of the Patient's Kidneys at Admission (Panel A) and Six Months after the Placement of a Stent–Graft (Panel B). One week after admission, acute mesenteric ischemia developed. A stent–graft (a stent covered with a Dacron graft) was implanted in the thoracic aorta to close the main entry tear and restore effective flow in the true lumen, after which signs of mesenteric ischemia gradually regressed. The patient was discharged without symptoms on day 19; at the time of discharge, when he was being treated with four oral antihypertensive agents, his systolic blood pressure was 120 mm Hg. Duplex ultrasonographic images showed satisfactory blood flow in the mesenteric and renal arteries. A follow-up CT scan obtained six months later (Figure 1B) showed two normal-size kidneys (right, 113.2 mm; left, 128.4 mm). Scintigraphic studies indicated excellent functional recovery of the right kidney, with symmetric uptake of the tracer. Silent type B aortic dissections carry a risk of chronic renal hypoperfusion. The case presented here shows the insidious onset of a renovascular hypertension. The recovery of perfusion in the right kidney and its return to a normal size were surprising. Predictive factors for effective renal revascularization are a glomerular pressure of more than 30 mm Hg,2 a peripheral resistance index of less than 0.80,3 and a kidney size of more than 9 cm.4 This case presented all of the necessary conditions that allowed "hibernation" of the right kidney with residual perfusion and recovery after effective reperfusion. The regression of the compensatory hypertrophy of the left kidney is also notable. Renal hypoperfusion in aortic dissection is often missed, because there are few overt symptoms. Systematic screening for renal hypoperfusion, associated with the good results of endovascular techniques,5 can prevent renal atrophy that is still too frequently discovered at a late stage. Jean-Philippe Verhoye, M.D. Bertrand De Latour, M.D. Jean-Fran?ois Heautot, M.D., Ph.D. University Hospital Pontchaillou 35000 Rennes, France jverhoye@stanford.edu References Williams DM, Lee DY, Hamilton BH, et al. The dissected aorta: part III. Anatomy and radiologic diagnosis of branch-vessel compromise. Radiology 1997;203:37-44. Mesna L, Delahousse M, Raynaud A, et al. Delayed angioplasty after renal thrombosis. Am J Kidney Dis 2003;41:E9-E12. Radermacher J, Chavan A, Bleck J, et al. Use of Doppler ultrasonography to predict the outcome of therapy for renal-artery stenosis. N Engl J Med 2001;344:410-417. Soulez G, Therasse E, Qanadli SD, et al. Prediction of clinical response after renal angioplasty: respective value of renal Doppler sonography and scintigraphy. AJR Am J Roentgenol 2003;181:1029-1035. Dake MD, Kato N, Mitchell RS, et al. Endovascular stent-graft placement for the treatment of acute aortic dissection. N Engl J Med 1999;340:1546-1552....查看详细 (4095字节)

☉ 11325809:Insulin Analogues
To the Editor: In regard to the review of insulin analogues by Hirsch (Jan. 13 issue),1 recurrent hypoglycemia is a major impediment to the achievement of good metabolic control, as defined by the Diabetes Control and Complications Trial.2 Furthermore, asymptomatic nocturnal hypoglycemic episodes are important because they reduce counterregulation and thereby increase the risk of subsequent prolonged and severe hypoglycemia, associated occasionally with coma.3 This is particularly true for small children, who have been shown to sleep through episodes of prolonged hypoglycemia. The use of regular insulin before the evening meal leads to overinsulinization during the early part of the night, when parents most often note hypoglycemia in their children. The short-acting analogues have a clear advantage over regular insulin by reducing this risk, as has been demonstrated in a recent study in which overnight blood glucose profiles were compared with the use of two types of insulin before the evening meal.4 In our clinical setting, in which a multiple-injection insulin regimen is implemented even in toddlers, we recommend the use of the short-acting analogue before the evening meal and the use of regular insulin before breakfast and lunch, in order to allow for in-between snacks, as suggested by Hirsch.1 Angelika Mohn, M.D. Maria Marcovecchio, M.D. Francesco Chiarelli, M.D. University of Chieti 66100 Chieti, Italy amohn@unich.it References Hirsch IB. Insulin analogues. N Engl J Med 2005;352:174-183. The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993;3:615-622. Veneman T, Mitrakou A, Mokan M, Cryer P, Gerich J. Induction of hypoglycemia unawareness by asymptomatic nocturnal hypoglycemia. Diabetes 1993;42:1233-1237. Ford-Adams ME, Murphy NP, Moore EJ, et al. Insulin lispro: a potential role in preventing nocturnal hypoglycaemia in young children with diabetes mellitus. Diabet Med 2003;20:656-660. To the Editor: New insulin analogues have revolutionized the treatment of diabetes mellitus in recent years. However, as Hirsch mentions, there is serious oncologic concern about some of these new substances. As compared with human insulin, glargine, a long-acting insulin analogue, has an affinity for the insulin-like growth factor (IGF) receptor that is six times as high and also increases the mitosis rate by a factor of eight in a human osteosarcoma cell line.1 Given this higher receptor affinity and the fact that high levels of circulating IGF-1 are associated with an increased risk of solid tumors2 and leukemia,3 especially in young patients, the use of glargine in children should probably be reconsidered, since this group of patients is most likely to have long-term adverse effects. Michael C. Haffner Marcus P. Kufner Innsbruck Medical University 6020 Innsbruck, Austria References Kurtzhals P, Sch?ffer L, S?rensen A, et al. Correlations of receptor binding and metabolic and mitogenic potencies of insulin analogs designed for clinical use. Diabetes 2000;49:999-1005. Renehan AG, Zwahlen M, Minder C, O'Dwyer ST, Shalet SM, Egger M. Insulin-like growth factor (IGF)-I, IGF binding protein-3, and cancer risk: systematic review and meta-regression analysis. Lancet 2004;363:1346-1353. Petridou E, Desspyris N, Spanos E, et al. Insulin-like growth factor-I and binding protein-3 in relation to childhood leukemia. Int J Cancer 1999;80:494-496. To the Editor: In his well-balanced review of insulin analogues, Hirsch states that "premixed insulin analogues should fill a relatively small niche for most patients who require prandial insulin, with two exceptions: those with type 2 diabetes who eat relatively small lunches and those who are unable to use more sophisticated regimens." This statement ignores an important issue: premixed insulin is the most widely used insulin formulation.1 Furthermore, 46 percent of patients with type 2 diabetes can achieve the glycosylated hemoglobin target of 6.5 percent or less with premixed analogues.2 It may appear that twice-daily premixed insulin is inferior to a more sophisticated physiological insulin substitution. However, my colleagues and I have recently shown that in a four-year study of patients with type 2 diabetes who used twice-daily premixed insulin aspart, there was a significant reduction of major hypoglycemic events and insulin needs for average-size lunches were covered, with good postprandial glucose control.3,4 Therefore, the use of premixed insulin analogues does provide an improvement in insulin therapy in a large number of patients with type 2 diabetes. Bernhard O. Boehm, M.D. University of Ulm 89070 Ulm, Germany bernhard.boehm@medizin.uni-ulm.de Dr. Boehm reports having received research grants from NovoNordisk and Aventis. References Mudaliar S, Edelman SV. Insulin therapy in type 2 diabetes. Endocrinol Metab Clin North Am 2001;30:935-982. Raskin P, Rojas P, Allen E. Comparison of twice daily aspart 70/30 (BIAsp 70/30) with once-daily insulin glargine (GLA) in patients with type 2 DM on oral antidiabetic agents. Diabetes 2004;53:Suppl 2:A143-A143. abstract. Boehm BO, Home PD, Behrend C, Kamp NM, Lindholm A. Premixed insulin aspart 30 vs. premixed human insulin 30/70 twice daily: a randomized trial in Type 1 and Type 2 diabetic patients. Diabet Med 2002;19:393-399. Boehm BO, Vaz JA, Brondsted L, Home PD. Long-term efficacy and safety of biphasic insulin aspart in patients with type 2 diabetes. Eur J Intern Med 2004;5:496-502. Dr. Hirsch replies: Mohn and colleagues bring up an important point: the addition of insulin analogues provides us with new tools to become more creative in dealing with real-life glycemic challenges. With unrestrained creativity, there are many situations in which the use of a combination of standard insulins and analogues can resolve clinical problems. This is in contrast to the comments by Boehm, who suggests that a fixed-ratio insulin is appropriate for many patients with type 2 diabetes. Although I agree that for many patient (and perhaps physician) populations, a more sophisticated regimen of basal and prandial insulin replacement will not be successful, much of the success with a premixed regimen is based on the degree of insulin deficiency, in addition to a given patient's ability to maintain a consistent diet (in terms of both calories and the timing of the meals). Boehm and his colleagues reported that after 24 months of treatment with biphasic insulin aspart, the mean (±SE) glycosylated hemoglobin level was 8.35±0.20 percent,1 which is well above target levels in the United States and Europe. Haffner and Kufner inquire about the increased affinity of insulin glargine for the IGF-1 receptor and the increased mitosis rate in a human osteosarcoma cell line. Although this is an understandable concern, it is reassuring that in the four years since insulin glargine was introduced in the United States, there have been no reports of acceleration of diabetic retinopathy. It should also be noted that in at least one other study in human skeletal-muscle cells, no differences in mitogenic effects were revealed between insulin glargine and human insulin.2 Since hypoglycemia is the rate-limiting factor for all insulin therapy, it seems to me that the risk-benefit ratio for the use of glargine outweighs any theoretical risk of problems not reported to date. We clearly need more data about the risk of hypoglycemia with insulin glargine as compared with neutral protein Hagedorn insulin in children. However, as I noted in my review, the risk–benefit ratio for these theoretical concerns about IGF-1–receptor binding and an increased mitosis rate is not as clear in pregnant women, and most authors would not use insulin glargine in this population. Irl B. Hirsch, M.D. University of Washington School of Medicine Seattle, WA 98195-6176 ihirsch@u.washington.edu References Boehm BO, Vaz JA, Brondsted L, Home PD. Long-term efficacy and safety of biphasic insulin aspart in patients with type 2 diabetes. Eur J Intern Med 2004;5:496-502. Ciaraldi TP, Carter L, Seipke G, Mudaliar S, Henry RR. Effects of the long-acting insulin analog insulin glargine on cultured human skeletal muscle cells: comparisons to insulin and IGF-I. J Clin Endocrinol Metab 2001;86:5838-5847....查看详细 (8637字节)
☉ 11325810:Therapy for Colorectal Cancer
To the Editor: We believe Meyerhardt and Mayer's discussion of regional, targeted therapies for colorectal cancer (Feb. 3 issue)1 is incomplete. Regional infusion of interleukin-2 or interferon alfa through the hepatic artery, combined with chemotherapy, yields better results than chemotherapy alone in patients with metastatic colorectal disease.2,3,4 Moreover, modulation of fluorouracil-metabolizing enzymes by interleukin-2 appears to enhance the effectiveness of this chemotherapeutic agent. In addition, major surgery for liver metastases induces stimulation of angiogenesis and immunosuppression consisting of lymphocytopenia, reductions in the blood levels of antitumor interleukin-2 and interleukin-12, and increases in the level of immunosuppressive interleukin-6.5 On the other hand, according to clinical trials, preoperative subcutaneous administration of interleukin-2 may prevent surgery-induced immunosuppression, and may counteract surgery-induced stimulation of angiogenesis either by reducing the increased levels of angiogenic vascular endothelial growth factor observed during surgery or by opposing the decline in the blood levels of antiangiogenic and antitumor interleukin-12. Interleukin-2 administration appears to be well tolerated and without cardiovascular complications during the perioperative period.5 Therefore, surgeons might consider introducing this preoperative immunotherapeutic approach.5 Jannis Kountouras, M.D., Ph.D. Christos Zavos, M.D. Dimitrios Chatzopoulos, M.D. Aristotle University of Thessaloniki 546 42 Thessaloniki, Greece jannis@med.auth.gr References Meyerhardt JA, Mayer RJ. Systemic therapy for colorectal cancer. N Engl J Med 2005;352:476-487. Kountouras J, Zavos C, Chatzopoulos D, Zavos N, Boura P, Safioleas M. Locoregional immunochemotherapy in primary and metastatic liver disease: meta-analysis and review of literature. Hepatogastroenterology 2003;50:1506-1510. Lygidakis NJ, Sgourakis G, Vlachos L, et al. Metastatic liver disease of colorectal origin: the value of locoregional immunochemotherapy combined with systemic chemotherapy following liver resection: results of a prospective randomized study. Hepatogastroenterology 2001;48:1685-1691. Sato T. Locoregional immuno(bio)therapy for liver metastases. Semin Oncol 2002;29:160-167. Kountouras J, Zavos C, Chatzopoulos D. Immunotherapy in metastatic liver disease. In: Lee F, ed. Liver cancer: new research. New York: Nova Science (in press). To the Editor: Many patients with a diagnosis of colorectal cancer are young and may be cured. Fertility and reproductive issues among patients who have received fluorouracil as adjuvant therapy have rarely been addressed. A 31-year-old woman was examined because of hematochezia. A colonoscopy showed a tumor in the sigmoid colon. A left hemicolectomy was performed. Pathological examination showed a 3-cm adenocarcinoma and metastatic disease in two lymph nodes examined. The patient received six cycles of fluorouracil plus leucovorin for 5 days every 28 days. At 30 months of follow-up, she had no evidence of relapse. She later became pregnant. Her pregnancy was uneventful, and a normal child was delivered. The limited value of this report should be complemented by data gathered after long-term follow-up from randomized trials. In the meantime, this case points to the real benefits that adjuvant chemotherapy may offer to some young patients. Gustavo Jankilevich, M.D. Hospital Durand 1426 Buenos Aires, Argentina gustavojank@hotmail.com To the Editor: In reading the review article by Meyerhardt and Mayer, I was unable to find any indication of quality of life in association with the extension of survival (from 6 to more than 20 months) documented in Figure 1. The question really is this: What was the quality of life during the months gained as a result of the blast of toxic chemicals? My observation is that patients who have received such treatment are in fact quite miserable. It is not uncommon to hear patients say, "I wish I had never had it." I strongly recommend that investigators embarking on these highly toxic endeavors include quality-of-life measurements. William S. Masland, M.D. 2475 Ave. A Yuma, AZ 85364 To the Editor: Meyerhardt and Mayer cite several articles in support of their statement that "the use of chemotherapy in patients with metastatic disease prolongs survival and enhances quality of life in comparison to palliative care alone." The World Health Organization describes palliative care as an "impeccable assessment and treatment of pain and other problems, physical, psychosocial and spiritual."1 The articles cited by Meyerhardt and Mayer do not mention a treatment group receiving palliative care defined in this way. One report describes supportive care as "symptomatic therapy and/or assistance of a psychotherapist,"2 which hardly constitutes palliative care. Given Mayer's endorsement of palliative care,3 we are surprised at the noncritical acceptance of the studies cited. We are not arguing that chemotherapy may not offer an advantage in terms of quality of life over palliative care; rather, studies either have not yet tested this hypothesis or have not described their methods of supportive care sufficiently. Palliative interventions have been well described, so studies in which the "best supportive care" is used should include standardized protocols for palliation. Otherwise, quality-of-life claims, such as those made by the authors of this review, are likely to be subject to ongoing criticism. Shiri Etzioni, M.D. Ken Rosenfeld, M.D. Greater Los Angeles Veterans Hospital Los Angeles, CA 90073 shiri.etzioni@med.va.gov References World Health Organization. Palliative care. 2005. (Accessed April 8, 2005, at http://www.who.int/cancer/palliative.) Cunningham D, Pyrhonen S, James RD, et al. Randomised trial of irinotecan plus supportive care versus supportive care alone after fluorouracil failure for patients with metastatic colorectal cancer. Lancet 1998;352:1413-1418. Cancer care during the last phase of life. J Clin Oncol 1998;16:1986-1996. The authors reply: Drs. Etzioni and Rosenfeld address the need for clearly defined definitions to help distinguish "palliative care" from the "best supportive care." In the area of advanced colorectal cancer, multiple randomized trials conducted more than 15 years ago showed that the use of chemotherapy prolongs survival when compared with the "best supportive care,"1 and some of these trials also indicated that anticancer treatment improves the "quality of life." Although one may question the precise definition of "palliative care," the fact that the cohorts of patients assigned to systemic treatment survived two to three times as long as those not assigned to chemotherapy and appeared, according to "quality of life" measurements, to have had a reduction in symptoms during that time appears to us to represent a positive step forward. Dr. Masland's reference to systemic treatment for colorectal cancer as a "blast of toxic chemicals" should be balanced by the reality that such treatment is routinely given on an outpatient basis, that it usually allows patients to continue the majority of their normal professional and social activities, and as illustrated by Dr. Jankilevich, that it often does not interfere with subsequent fertility. Dr. Kountouras and colleagues focus on the regional and systemic use of interleukin-2 or interferon alfa in the treatment of patients with advanced colorectal cancer. Meta-analyses, however, have not shown a survival advantage with hepatic arterial infusion among patients with unresectable liver metastases2 or among those who have undergone a hepatic metastasectomy.3 Furthermore, randomized trials have failed to demonstrate any benefit of the addition of interleukin-2 or interferon alfa to fluorouracil for advanced disease.4,5 Jeffrey A. Meyerhardt, M.D., M.P.H. Robert J. Mayer, M.D. Dana–Farber Cancer Institute Boston, MA 02115 References Simmonds PC. Palliative chemotherapy for advanced colorectal cancer: systematic review and meta-analysis. BMJ 2000;321:531-535. Meta-Analysis Group in Cancer. Reappraisal of hepatic arterial infusion in the treatment of nonresectable liver metastases from colorectal cancer. J Natl Cancer Inst 1996;88:252-258. Clancy TE, Dixon E, Perlis R, Sutherland FR, Zinner MJ. Hepatic arterial infusion after curative resection of colorectal cancer metastases: a meta-analysis of prospective clinical trials. J Gastrointest Surg 2005;9:198-206. Heys SD, Eremin O, Ruggeri EM, et al. A phase III study of recombinant interleukin-2, 5-fluorouracil and leucovorin versus 5-fluorouracil and leucovorin in patients with unresectable or metastatic colorectal carcinoma. Eur J Cancer 1995;31:19-25. Thirion P, Piedbois P, Buyse M, et al. Alpha-interferon does not increase the efficacy of 5-fluorouracil in advanced colorectal cancer. Br J Cancer 2001;84:611-620....查看详细 (9158字节)
☉ 11325811:Nucleophosmin in Acute Myelogenous Leukemia
To the Editor: Falini et al. (Jan. 20 issue)1 report an abnormal cytoplasmic localization of nucleophosmin (NPM) in 35 percent of specimens from patients with acute myelogenous leukemia. In these patients the NPM gene was mutated, which resulted in a frame shift. The authors state that tryptophan residues at positions 288 and 290 of NPM played a role in the cytoplasmic translocation of NPM. However, these residues are responsible only for nucleolar localization of NPM, not for cytoplasmic localization.2 We found a motif containing leucine-valine residues, known as the nuclear-export-signal (NES) motif, in the C-terminal of mutated NPMs A to F in Figure 4B of the article (Figure 1). The typical nuclear-export signal consists of a short stretch of hydrophobic amino acids (predominantly leucines) and fits the consensus sequence Lx(1-3)Lx(2-3)LxL (with x indicating any residues).3 NES-containing molecules are recognized by nuclear export receptor CRM1 and are then exported to cytoplasm.4 We believe that the NES generated by the mutation of the NPM gene is important for cytoplasmic localization of NPM and tumorigenesis in acute myelogenous leukemia. Figure 1. Nuclear-Export-Signal (NES) Motif in the C-Terminal of Nucleophosmin (NPM) Mutants. A short and hydrophobic motif, like a consensus sequence of NES, is found in the C-terminal of all the NPM mutants. Putative residues of an NES are shaded. Masao Nakagawa, M.D. Yoshihiro Kameoka, M.D. Ritsuro Suzuki, M.D. Aichi Cancer Center Nagoya 464-8681, Japan mnakagawa@aichi-cc.jp References Falini B, Mecucci C, Tiacci E, et al. Cytoplasmic nucleophosmin in acute myelogenous leukemia with a normal karyotype. N Engl J Med 2005;352:254-266. Nishimura Y, Ohkubo T, Furuichi Y, Umekawa H. Tryptophans 286 and 288 in the C-terminal region of protein B23.1 are important for its nucleolar localization. Biosci Biotechnol Biochem 2002;66:2239-2242. Henderson BR, Eleftheriou A. A comparison of the activity, sequence specificity, and CRM1-dependence of different nuclear export signals. Exp Cell Res 2000;256:213-224. Kau TR, Way JC, Silver PA. Nuclear transport and cancer: from mechanism to intervention. The authors reply: We find the hypothesis of Dr. Nakagawa and colleagues on the mechanism underlying the abnormal cytoplasmic localization of NPM in a subgroup of cases of acute myelogenous leukemias (acute myelogenous leukemia positive for cytoplasmic NPM) very attractive and worth validating experimentally. However, the mechanism of nuclear export might be more complex than they propose, because mutations affecting tryptophans at positions 288 and 290 could also play a role. Tryptophans regulate nucleolar localization of NPM,1 and an inability of the mutated NPM protein to bind to nucleoli may cause its nucleoplasmic accumulation. This defect could facilitate export of the mutated NPM protein, making more of it available for binding to CRM1 through NES. Other NPM mutants will probably be found, and they will indicate whether all NPM mutants bear the same NES motif. Brunangelo Falini, M.D. Cristina Mecucci, M.D., Ph.D. Massimo F. Martelli, M.D. Policlinico Monteluce 06122 Perugia, Italy faliniem@unipg.it References Nishimura Y, Ohkubo T, Furuichi Y, Umekawa H. Tryptophans 286 and 288 in the C-terminal region of protein B23.1 are important for its nucleolar localization. Biosci Biotechnol Biochem 2002;66:2239-2242....查看详细 (3514字节)
☉ 11325812:Decline in Mortality with Varicella Vaccination
To the Editor: Nguyen et al. (Feb. 3 issue)1 report on the effect of the U.S. varicella vaccination program on disease-related mortality. The effectiveness of such programs also includes reducing severe varicella-associated complications. In Italy, from 1995 to 2003, when no universal childhood varicella vaccination program was in effect, we documented 303 admissions (median age of patients, 4.2 years; range, 0 to 15) to a children's research hospital for varicella for a total of 2420 days of hospitalization. Thirty-nine patients (13 percent) had varicella-associated complications (1.2 percent of admissions for varicella), including 13 with central nervous system involvement and 7 with severe bacterial superinfections. No patient died, but stroke occurred in four children (age range, 6 months to 6 years) (Figure 1), with hemiparesis, facial paralysis, or both 2 to 30 days after the onset of exanthema, as previously described.2,3 All four patients had severe sequelae. Universal varicella vaccination not only reduces mortality but also provides an effective means of limiting severe and incapacitating disease-related complications. Figure 1. Cerebral Magnetic Resonance Image Showing Ischemic Hemorrhagic Lesions (Panel A, Arrow) and Hypovascularization with Occlusion of the Middle Cerebral Artery (Panel B, Arrow). Raffaella Giacchino, M.D. Giuseppe Losurdo, M.D. Elio Castagnola, M.D. G. Gaslini Children's Hospital 16147 Genoa, Italy raffaellagiacchino@ospedale-gaslini.ge.it...查看详细 (1533字节)

☉ 11325813:Alcohol and Cognitive Function in Older Women
To the Editor: Stampfer et al. (Jan. 20 issue)1 suggest that "women who consume up to one drink per day have less cognitive impairment . . . than nondrinkers," on the basis of the authors' data from the Nurses' Health Study and findings reported in the literature. A significant limitation of the study by Stampfer et al. is its low generalizability. On the basis of their exclusion criteria, the findings are applicable only to relatively well educated women with very stable drinking patterns who have no history of antidepressant use. Furthermore, a major threat to the study's external validity appears to be its nonrandom selection of subjects. We agree with the point made by Evans and Bienias in their accompanying editorial2 that older adults in good mental and physical health may be more likely than their less healthy peers to consume alcohol in social situations. Thus, cognitive and health characteristics of the participating women may be determining the study's alcohol-intake groups. Finally, caution is necessary when recommending any amount of alcohol to older adults, since the toxic effects of alcohol can be exacerbated with age as a result of changes in body composition (e.g., decreased lean body mass and total body water). Kara S. Schmidt, Ph.D. David J. Libon, Ph.D. University of Medicine and Dentistry of New Jersey School of Osteopathic Medicine Stratford, NJ 08084 schmidka@umdnj.edu References Stampfer MJ, Kang JH, Chen J, Cherry R, Grodstein F. Effects of moderate alcohol consumption on cognitive function in women. N Engl J Med 2005;352:245-253. Evans DA, Bienias JL. Alcohol consumption and cognition. N Engl J Med 2005;352:289-290. To the Editor: Stampfer et al. report that women who consume a moderate amount of alcohol have less cognitive impairment and better cognitive function than nondrinkers. However, the antiinflammatory action of alcohol is not clearly mentioned among the plausible explanations for this effect. Moderate alcohol consumption has been shown to be related to a decrease in markers of systemic inflammation.1,2 Since inflammatory mechanisms are hypothesized to be involved in the pathogenesis of cognitive impairment,3,4,5 the beneficial action of moderate alcohol intake on cognitive function could also be related to its antiinflammatory activity. Francesca Pezzetta, M.D. Presidio Ospedaliero di San Vito al Tagliamento 33078 San Vito al Tagliamento, Italy Luca Mascitelli, M.D. Comando Brigata Alpina Julia 33100 Udine, Italy lumasci@libero.it References Albert MA, Glynn RJ, Ridker PM. Alcohol consumption and plasma concentration of C-reactive protein. Circulation 2003;107:443-447. Imhof A, Woodward M, Doering A, et al. Overall alcohol intake, beer, wine, and systemic markers of inflammation in western Europe: results from three MONICA samples (Augsburg, Glasgow, Lille). Eur Heart J 2004;25:2092-2100. McGeer EG, McGeer PL. Brain inflammation in Alzheimer disease and the therapeutic implications. Curr Pharm Des 1999;5:821-836. Teunissen CE, van Boxtel MP, Bosma H, et al. Inflammation markers in relation to cognition in a healthy aging population. J Neuroimmunol 2003;134:142-150. Yaffe K, Lindquist K, Penninx BW, et al. Inflammatory markers and cognition in well-functioning African-American and white elders. Neurology 2003;61:76-80. To the Editor: Stampfer and colleagues report that older women who consumed less than 15 g of alcohol per day had better cognitive scores and a lower risk of cognitive decline than nondrinkers. No significant associations were found for higher levels of alcohol consumption (15 to 30 g per day), and no differences were found according to the type of beverage. These conclusions may underscore the potential effects of wine consumption as a constituent of the Mediterranean diet. For instance, among 13,462 women enrolled in an Italian collaborative pharmacoepidemiologic study, Gruppo Italiano di Farmacovigilanza nell'Anziano (GIFA),1 all levels of alcohol consumption up to 39 g per day were associated with a lower probability of cognitive impairment (odds ratio as compared with no alcohol consumption, 0.69; 95 percent confidence interval, 0.62 to 0.76), after adjustment for age, coexisting conditions, and medications. This result is in keeping with the observed benefits of up to 29 g of alcohol per day in older populations adhering to a Mediterranean diet.2 The question of whether such dose–effect differences among studies should be ascribed to consumption of red wine or to increased rates of alcohol elimination associated with regular drinking during meals3 deserves further investigation. Giuseppe Zuccala, M.D. Emanuele Marzetti, M.D. Roberto Bernabei, M.D. Catholic University 00168 Rome, Italy giuseppe_zuccala@rm.unicatt.it References Carosella L, Pahor M, Pedone C, et al. Pharmacosurveillance in hospitalized patients in Italy: study design of the `Gruppo Italiano di Farmacovigilanza nell'Anziano' (GIFA). Pharmacol Res 1999;40:287-295. Knoops KT, de Groot LC, Kromhout D, et al. Mediterranean diet, lifestyle factors, and 10-year mortality in elderly European men and women: the Hale Project. JAMA 2004;292:1433-1439. Ramchandani VA, Kwo PY, Li TK. Effect of food and food consumption on alcohol elimination rates in healthy men and women. J Clin Pharmacol 2001;41:1345-1350. The authors reply: Drs. Schmidt and Libon note that our finding of an inverse relation between moderate alcohol consumption and cognitive decline may not be generalizable. We agree; taken by themselves, our findings (and those of any single study) may have limited generalizability. However, generalizability is best addressed by determining whether other studies of alcohol and cognitive function in populations with different characteristics have similar results. As we describe in the Discussion section of our article, similar inverse associations were observed among U.S. blacks, French and Dutch populations, Japanese Americans, and other populations with varying educational backgrounds and drinking patterns. Since we submitted our manuscript, two other articles have been published: a report of the Women's Health Initiative Memory Study1 and a report on a study of Japanese Americans and white Americans2; both studies show an apparent benefit of moderate alcohol consumption. Moreover, a relation between moderate alcohol consumption and better cognition has biologic support. Thus, we believe our findings are generalizable to groups other than the specific population in our study. Drs. Schmidt and Libon also mention the possibility of confounding. Although no observational study can be free of confounding by unknown factors, we took into account a wide range of physical, mental, and social variables (including depression), and adjustment for these variables had little effect on the results. We chose specifically to select women with long-term stable drinking patterns in order to minimize the possibility of reverse causation (i.e., that the level of cognitive function predetermined the drinking patterns). Drs. Schmidt and Libon express concern about alcohol consumption by older adults. Nobody would argue against caution in recommending alcohol, as we repeatedly emphasize in our article. However, total abstinence has been consistently linked with higher rates of coronary disease and overall mortality in many studies3,4,5; thus, the potential health benefits of moderate alcohol might be considered, too. We fully agree with Drs. Pezzetta and Mascitelli that an antiinflammatory mechanism is plausible; space constraints limited our discussion of this issue. Finally, we were unaware of the GIFA data provided by Zuccala et al., which add further support to the overall hypothesis that there may be an inverse relation between moderate alcohol consumption and cognitive decline. Clearly, further study is needed to define the optimal levels of intake. Meir J. Stampfer, M.D. Jae Hee Kang, Sc.D. Francine Grodstein, Sc.D. Brigham and Women's Hospital Boston, MA 02115 References Espeland MA, Gu L, Masaki KH, et al. Association between reported alcohol intake and cognition: results from the Women's Health Initiative Memory Study. Am J Epidemiol 2005;161:228-238. Bond GE, Burr R, McCurry SM, et al. Alcohol, gender, and cognitive performance: a longitudinal study comparing older Japanese and non-Hispanic white Americans. J Aging Health 2004;16:615-640. Rimm EB, Stampfer MJ. Alcohol abstinence: a risk factor for coronary heart disease. Heart Dis Updates 2000;2:1-9. Thun MJ, Peto R, Lopez AD, et al. Alcohol consumption and mortality among middle-aged and elderly U.S. adults. N Engl J Med 1997;337:1705-1714. Gmel G, Gutjahr E, Rehm J. How stable is the risk curve between alcohol and all-cause mortality and what factors influence the shape? A precision-weighted hierarchical meta-analysis. Eur J Epidemiol 2003;18:631-642....查看详细 (9126字节)
☉ 11325814:Platelet-Derived Growth Factor CC — A Clinically Useful Angiogenic Factor at Last?
Impaired vascularization that limits the supply of oxygen to tissue results in ischemic heart disease or peripheral arterial occlusive disease — potentially fatal conditions. Cardiologists therefore seek strategies to augment the blood supply, whereas cancer researchers focus on the opposite: preventing tumor growth by blocking tumor vascularization. And so efforts have focused on unraveling the molecular mechanisms that underlie postnatal vascularization. The identification of growth factors with positive or negative effects on the formation of blood vessels is one branch of this research. Along these lines, Li and colleagues1 have reported that a member of the platelet-derived growth factor (PDGF) family, PDGF-CC, effects neovascularization and blood flow in two experimental models of ischemia. PDGF was originally isolated from human platelets and was one of the first growth factors shown to regulate vessel maturation. Four members of the PDGF family have since been identified: PDGF-A, PDGF-B, PDGF-C, and PDGF-D. These must form dimers (AA, AB, BB, CC, and DD) to be physiologically active.2 In particular, PDGF-BB has an essential role in the maturation of nascent blood vessels: it recruits mural cells (smooth-muscle cells and pericytes) and is important in tumor lymphangiogenesis.3 However, the therapeutic potential of PDGF-BB to augment the blood supply is limited, and it can achieve profound and sustained neovascularization only when administered with other angiogenic growth factors.4 In contrast, Li et al. have recently shown that infusion of PDGF-CC alone increased neovascularization and blood flow in two models of ischemia (Figure 1).1 Figure 1. Multiple Actions of PDGF-CC. A recent study by Li et al.1 showed how PDGF-CC drives angiogenesis. First, PDGF-CC activates the PDGF receptor (PDGF-R), the expression of which is up-regulated in sprouting vessels. PDGF-CC thereby triggers the formation of blood vessels by stimulating the migration and sprouting of preexisting endothelial cells and by recruiting mural cells to the nascent vessels. Second, high levels of PDGF-CC in the blood enhance the mobilization of endothelial progenitor cells from the bone marrow. Endothelial progenitor cells home to sites of ischemia, where they differentiate in a PDGF-CC–dependent manner into endothelial and smooth-muscle cells. VEGF denotes vascular endothelial growth factor. Why is PDGF-CC effective in the context of ischemia? It acts on the PDGF receptor , which is up-regulated in the sprouting vessels of ischemic hearts, and it thereby stimulates the migration of mature endothelial cells and smooth-muscle cells. It also promotes angiogenesis by triggering the release of vascular endothelial growth factor (VEGF), a powerful endothelial mitogen and angiogenic factor. Li et al. also found that infusing PDGF-CC into mice with ischemia initiated a process known as adult vasculogenesis. PDGF-CC stimulated the mobilization of endothelial progenitor cells, which home to sites of ischemia, thereby augmenting neovascularization.5 The authors also showed that, in vitro, the pool of precursor cells that gave rise to endothelial cells also gave rise to smooth-muscle cells — another key component of blood vessels — when stimulated with PDGF-CC. The induction of endothelial differentiation might be a consequence of the release of VEGF, which promotes endothelial differentiation of hematopoietic stem cells. However, the in vitro differentiation of precursor cells into both endothelial cells and smooth-muscle cells after the addition of a single growth factor represents a striking observation. The multiple actions of PDGF-CC would seem to contribute to its distinctive therapeutic profile in vivo. It is an attractive candidate for combination therapy with other growth factors, such as VEGF or basic fibroblast growth factor, both of which failed in phase 2 clinical trials to improve neovascularization in patients with ischemic heart disease. Certainly, the findings reported by Li et al. will stimulate further research into why the PDGF proteins have different activities, even though they have partially overlapping target receptors and induce similar signaling events in cell-culture studies. A better understanding of the action of PDGF may help refine strategies to improve neovascularization in patients with ischemic heart disease or peripheral arterial occlusive disease. Source Information From the Department of Molecular Cardiology, University of Frankfurt, Frankfurt, Germany. References Li X, Tjwa M, Moons L, et al. Revascularization of ischemic tissues by PDGF-CC via effects on endothelial cells and their progenitors. J Clin Invest 2005;115:118-127. Betsholtz C. Insight into the physiological functions of PDGF through genetic studies in mice. Cytokine Growth Factor Rev 2004;15:215-228. Vincent L, Rafii S. Vascular frontiers without borders: multifaceted roles of platelet-derived growth factor (PDGF) in supporting postnatal angiogenesis and lymphangiogenesis. Cancer Cell 2004;6:307-309. Cao R, Brakenhielm E, Pawliuk R, et al. Angiogenic synergism, vascular stability and improvement of hind-limb ischemia by a combination of PDGF-BB and FGF-2. Nat Med 2003;9:604-613. Losordo DW, Dimmeler S. Therapeutic angiogenesis and vasculogenesis for ischemic disease: part II: cell-based therapies. Circulation 2004;109:2692-2697....查看详细 (5462字节)
☉ 11325815:Multislice Computed Tomography for Pulmonary Embolism — A Technological Marvel
Rapid and accurate diagnosis of pulmonary embolism will improve survival and quality of life because treatment decreases mortality and the likelihood that thromboembolic pulmonary hypertension or the post-thrombotic syndrome will develop. The paramount challenge is to consider pulmonary embolism as a diagnostic possibility and therefore order the appropriate diagnostic tests and institute timely and effective therapy. Computed tomographic (CT) scanning of the chest has revolutionized our diagnostic approach to suspected pulmonary embolism. Ventilation–perfusion lung scanning used to be the pivotal imaging test, but the lung scan was problematic because it rarely provided a definitive "high probability" or "normal" result. Its ambiguity led to an array of murky descriptions, such as "intermediate probability," "indeterminate probability," "moderate probability," "low end of moderate probability," or "moderately high probability." Clinicians responded to this confusion by summoning expert subspecialists for urgent consultation to declare whether pulmonary embolism was present and whether invasive pulmonary angiography was warranted to make a definitive diagnosis. Selective pulmonary angiography, which was then the "gold standard," is uncomfortable for the patient but safe when performed by properly trained staff. Still, passage of a catheter through the right ventricle in patients prone to arrhythmia can provoke nonsustained ventricular tachycardia. After positioning and securing the catheter, the staff coaches patients with dyspnea to hold their breath for about 30 seconds. Each lung requires at least two separate angiographic views and, therefore, at least two injections. Aside from the hot, flushed feeling produced by the angiographic dye, some patients have transient hypotension and coughing spasms from the bolus of contrast material delivered by the automated power injector. Coughing renders angiographic images blurry and often necessitates repeating the injection. Even when successfully completed, these studies are often difficult to interpret beyond third-order vessels. I can attest to the disagreement among angiographic readers on the basis of the many angiogram-scoring sessions that I have chaired for clinical trials. The advent of chest CT scanning for the diagnosis of pulmonary embolism was hailed as an improvement, even before rigorous studies were undertaken. By 2001, CT scanning was being used more often than lung scanning to investigate suspected pulmonary embolism.1 There are now multiple generations of CT scanners, but even first-generation machines delivered images that were dramatic in clarity, rapidly acquired, and accurate in delineating the proximal pulmonary arterial tree. This noninvasive technology has evolved rapidly. A 16-slice multidetector-row CT scanner can image the entire chest with submillimeter resolution and requires a breath-hold of less than 10 seconds.2 Contemporary scanners can provide information about massive pulmonary embolism that can be helpful in planning emergency surgery, catheter embolectomy, or thrombolysis (Figure 1A). The latest generation of scanners can diagnose tiny submillimeter pulmonary embolism in sixth-order vessels (Figure 1B). These thrombi are so small that their clinical significance is uncertain.3 Figure 1. Two Cases of Pulmonary Embolism as Shown on Contrast-Enhanced 16-Slice Multidetector-Row Computed Tomography. Panel A is an anterior view of the chest of a 72-year-old man, showing extensive, acute central pulmonary embolism with a "saddle embolus" (arrows) extending into the left and right central pulmonary arteries. Panel B is a maximum-intensity projection in the coronal plane (seen from the posterior view) of a 64-year-old man with a history of vague pleuritic chest pain. The scan shows bilateral isolated emboli (arrows) in subsegmental arteries of the right and left lower lobes. (Courtesy of Drs. U. Joseph Schoepf and Douglas R. Lake, Medical University of South Carolina.) The diagnosis of pulmonary embolism is only one aspect of this technological breakthrough. The CT examination can image the legs, pelvis, and chest in a single study, often detecting the source of the clot.4 Regardless of whether pulmonary embolism is present, the information obtained from examining the lung parenchyma can identify small new lung cancers or pneumonia not visualized on chest radiography. After the diagnosis of pulmonary embolism is made, CT can help identify patients at high risk for death or major in-hospital complications. The prognosis can be assessed by detecting right ventricular enlargement on reconstructed four-chamber views. Right ventricular enlargement, defined as a ratio of the diameter of the right ventricle to the left ventricle that is more than 0.9, is a powerful predictor of outcome. In a series of 431 patients with pulmonary embolism at Brigham and Women's Hospital in Boston, right ventricular enlargement independently heralded an increase in mortality by a factor of five.5 Rapid risk stratification may help clinicians select the most appropriate candidates for thrombolysis or embolectomy. When single-detector helical CT was first introduced, Perrier et al. in Geneva studied 299 patients who presented with suspected pulmonary embolism because the investigators were skeptical about the accuracy of the scanning technique. They found that first-generation scanners missed 30 percent of patients with pulmonary embolism, and they concluded that this imaging test should not be used alone for suspected pulmonary embolism.6 Subsequently, Dutch investigators showed that the use of first-generation CT plus three serial venous ultrasonographic examinations of the leg on days 1, 3, and 7 for those with normal CT scans was a safe management strategy.7 Though safe, this approach was impractical and expensive. As reported in this issue of the Journal, Perrier et al. postulated that multislice CT, with its improved resolution, could serve as a stand-alone imaging test.8 They designed a prospective three-hospital study among patients suspected of having pulmonary embolism to determine whether leg ultrasonography was still necessary despite the advances in CT technology. They found, contrary to their experience with first-generation CT, that among patients with negative multislice CT scans, ultrasonography yielded an incremental rate of detection of venous thrombosis of only 0.9 percent. Thus, ultrasonography seems unnecessary in patients with negative multislice CT scans. The authors ruled out pulmonary embolism in 232 of their 674 patients who did not have a high clinical probability of pulmonary embolism and had normal measures of D-dimer on enzyme-linked immunosorbent assay (34 percent). Thus, one third of their patients who were suspected of having pulmonary embolism did not require CT. This approach is well validated9 and can help prevent multislice CT from becoming a runaway technology. We can marvel at contemporary CT, but we should not order scans of every patient presenting with dyspnea or pleurisy. Ruling out pulmonary embolism by the measurement of D-dimer, which is sensitive but not specific, is a logical step in managing health care costs. Although multislice CT scanning excluded pulmonary embolism and did not require ultrasonography as a complementary diagnostic test, ultrasonography itself cannot serve reliably as a surrogate for chest CT. In patients with suspected pulmonary embolism and elevated D-dimer levels, negative ultrasonography as a stand-alone test is inadequate to rule out pulmonary embolism. In the Geneva study, fewer than half of the patients with pulmonary embolism as confirmed by CT had ultrasonographic results that were positive for deep venous thrombosis, probably because the clot had embolized to the lungs. The thought-provoking article by Perrier et al. raises other fascinating questions. Thromboembolism developed in fewer than 2 percent of the patients with negative CT scans during the 90-day follow-up period. Of those scans, 89 percent were 4-slice and the rest were 16-slice. Yet, at our hospital, we are now installing a 64-slice scanner. Though our new scanner is a technological marvel, is it more of a frill than a necessity? In addition, since the current study showed that concomitant leg ultrasonography is unnecessary, do we really need CT venography of the legs and pelvis when we order CT to rule out pulmonary embolism? At some hospitals, the imaging of pelvic and leg veins is done automatically, without consulting the clinician. Are the additional radiation exposure and expense justified? In summary, the Geneva group has validated a strategy of using a clinical probability assessment, D-dimer screening, and multislice chest CT scanning, without the need for venous ultrasonography in patients whose CT scans are negative. This approach should streamline and expedite diagnosis, decrease the delay before the institution of therapy, and ultimately reduce the rates of death, chronic thromboembolic pulmonary hypertension, and the post-thrombotic syndrome. Source Information From the Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston. References Stein PD, Kayali F, Olson RE. Trends in the use of diagnostic imaging in patients hospitalized with acute pulmonary embolism. Am J Cardiol 2004;93:1316-1317. Schoepf UJ, Goldhaber SZ, Costello P. Spiral computed tomography for acute pulmonary embolism. Circulation 2004;109:2160-2167. Ravenel JG, Kipfmueller F, Schoepf UJ. CT angiography with multidetector-row CT for detection of acute pulmonary embolus. Semin Roentgenol 2005;40:11-19. Loud PA, Katz DS, Belfi L, Grossman ZD. Imaging of deep venous thrombosis in suspected pulmonary embolism. Semin Roentgenol 2005;40:33-40. Schoepf UJ, Kucher N, Kipfmueller F, Quiroz R, Costello P, Goldhaber SZ. Right ventricular enlargement on chest computed tomography: a predictor of early death in acute pulmonary embolism. Circulation 2004;110:3276-3280. Perrier A, Howarth N, Didier D, et al. Performance of helical computed tomography in unselected outpatients with suspected pulmonary embolism. Ann Intern Med 2001;135:88-97. van Strijen MJ, de Monye W, Schiereck J, et al. Single-detector helical computed tomography as the primary diagnostic test in suspected pulmonary embolism: a multicenter clinical management study of 510 patients. Ann Intern Med 2003;138:307-314. Perrier A, Roy P-M, Sanchez O, et al. Multidetector-row computed tomography in suspected pulmonary embolism. N Engl J Med 2005;352:1760-1768. Wells PS, Anderson DR, Rodger M, et al. Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and D-dimer. Ann Intern Med 2001;135:98-107....查看详细 (11045字节)
☉ 11325816:RSV Infection — Not for Kids Only
It is ironic that respiratory syncytial virus (RSV) infection in adults, though recognized for several decades, has been overlooked, at least in part, because of the importance of RSV in the pediatric population. The report by Falsey et al. in this issue of the Journal has placed the public health dimensions of RSV infection in adults in perspective.1 Though there are no immediate clinical implications of this study, it does have important repercussions for public health strategy and for the prioritization of the development of vaccines and antiviral agents. Several important features of the study design used by Falsey et al. deserve emphasis because they contribute substantially to the report's significance. Most common respiratory viral and bacterial infections are of short duration. It is therefore no surprise that cross-sectional studies regarding these infections abound in the literature and indeed provide valuable information regarding disease presentation, management, and prognosis. Prospective longitudinal studies in this field are few because of expense and complexity, but such studies provide unique perspectives, as exemplified by this report and others.1,2 With a prospective longitudinal design, baseline characteristics of the patients before the acquisition of infection can be clearly defined. The importance of clearly defined cohorts is well illustrated by the observed differences in the effect of RSV infection on healthy and high-risk groups — a distinction that would not have been recognized if this study had been confined to acutely ill, hospitalized patients. The establishment of baseline characteristics also allows for an accurate assessment of changes in measures — for example, changes in titers of antibody to RSV. Another goal of the study design was to conduct an investigation for influenzavirus infection simultaneously with the search for RSV infection. This structure provides a frame of reference to understand the epidemiology and clinical consequences of RSV infection. However, because vaccination prevents and attenuates a substantial proportion of influenza infections, the findings of this study apply only to populations with similarly high rates of influenza vaccination (>90 percent).3 In such populations, Falsey et al. have shown that the symptoms of RSV infection and influenza were similar and that RSV infection was twice as prevalent as influenza. In otherwise healthy elderly patients, RSV infection was a milder disease than influenza and was an uncommon cause of hospitalization or death. On the other hand, among elderly patients who had coexisting cardiac and pulmonary illnesses, the consequences of RSV infection (as measured in terms of emergency room visits, hospitalization rates, and mortality) were similar to those of influenza. With the advent of molecular diagnostics, additional techniques that diagnose viral infections more accurately and rapidly than culture and serologic testing are now available. These techniques provide nonculture detection of viruses in respiratory secretions, either by reverse-transcriptase–polymerase chain reaction (RT-PCR) or by direct immunofluorescence staining with monoclonal antibodies.4 Falsey et al. used RT-PCR in addition to viral culture and serologic testing, to enhance the diagnostic yield and provide a more accurate picture of the epidemiology of RSV infection. However, one must be cautious in making a diagnosis of RSV infection solely on the basis of a positive RT-PCR result. Colonization with RSV in patients with stable chronic obstructive pulmonary disease as detected by RT-PCR has been reported.5,6 This raises the possibility that the higher frequency of RSV infection reported in the high-risk cohort may reflect overdiagnosis on the basis of the RT-PCR assay in such colonized patients. In the study by Falsey et al., however, only 20 percent of cases of RSV infection were diagnosed by RT-PCR alone, and 83 percent of patients with a positive RT-PCR assay had immune responses. RT-PCR assay for RSV at baseline in the prospective cohorts would have further allayed this concern. A well-recognized phenomenon in the pathophysiology of respiratory tract infection is the viral–bacterial interaction, with simultaneous or sequential infections often occurring. The value of this study would have been enhanced if detailed diagnostic testing for bacterial infection had been included to establish what proportion of the illnesses involved a concomitant bacterial infection and what proportion represented viral processes alone.7 A more complete understanding of the epidemiology and pathogenesis of respiratory infections and consequently more appropriate treatment would be obtained if future research were to analyze for viral and bacterial infections simultaneously. Treatment of RSV infection in the elderly is largely supportive. Ribavirin has shown marginal efficacy in infants in some trials.8,9 However, the limited efficacy and high cost of ribavirin have limited its use to the treatment of immunocompromised patients and early treatment of severe RSV infection. Other antiviral agents are still in preclinical development. Palivizumab is a humanized monoclonal antibody against F protein that has become the standard for the prevention of RSV infection in high-risk infants; however, the agent is untested in the elderly.10 Clearly, there is a need for the development of better therapies for RSV infection. Establishment of RSV as an important pathogen in elderly and high-risk adults underscores the need for the development of vaccines that are effective in these populations. RSV causes repeated infections throughout life, raising the question of whether it will be possible to induce protective immune responses by vaccination. Several observations from experimental challenge studies in adults, epidemiologic studies in infants, and clinical trials involving passive immunization support the feasibility of developing effective vaccines for RSV.11 The presence of secretory neutralizing antibody correlates with protection against upper respiratory tract infection by RSV, serum neutralizing antibody to RSV is protective against lower respiratory tract infection, and cell-mediated immune responses directed against internal viral proteins appear to terminate infection.11 The populations that will benefit most from an effective RSV vaccine are infants and the elderly. Various vaccines will probably be needed for these target populations. Vaccine development for RSV was considerably slowed by the occurrence of enhanced or augmented disease after natural infection by RSV in seronegative infants who received formalin-inactivated RSV vaccine in the 1960s. Infants have immature immune systems that have not been exposed to RSV. Attenuated live-virus vaccines are most promising for infants since such vaccines can elicit a pattern of a potentially protective immune response that parallels natural disease, thus avoiding the induction of an immune response associated with enhanced disease. By contrast, the elderly have aging immune systems that have been exposed to the virus and often have coexisting, age-related illnesses. Subunit vaccines are most likely to be useful for immunization of elderly people and high-risk children and adults. Clinical trials of several subunit vaccines are under way.11,12 The World Health Organization has designated RSV as a high-priority pathogen for vaccine development. However, during the past decade, the enthusiasm for developing RSV vaccines has declined substantially among vaccine-development companies.9 A combination of the inherent scientific challenges, the high-risk nature of the target populations, and the enormous cost of vaccine development probably accounts for the lower priority given to RSV vaccine programs. Compounding the problem is a general lack of public awareness of RSV infection. Perhaps adults who have lost their parents or grandparents to RSV infection will form advocacy groups. Falsey et al. have provided us with a new understanding of the significance of RSV infection in adults, which should lead to increased vigilance for this infection on the part of the clinician. Furthermore, these observations should provide an impetus to renew research on the treatment and prevention of RSV infection — progress that is far from satisfactory at present. Dr. Murphy reports having a licensing agreement for bacterial vaccine development with Wyeth. Source Information From the Department of Medicine, Veterans Affairs Western New York Healthcare System; and the Department of Medicine, University at Buffalo, State University of New York — both in Buffalo, N.Y. References Falsey AR, Hennessey PA, Formica MA, Cox C, Walsh EE. Respiratory syncytial virus infection in elderly and high-risk adults. N Engl J Med 2005;352:1749-1759. Sethi S, Evans N, Grant BJB, Murphy TF. New strains of bacteria and exacerbations of chronic obstructive pulmonary disease. N Engl J Med 2002;347:465-471. Wongsurakiat P, Maranetra KN, Wasi C, Kositanont U, Dejsomritrutai W, Charoenratanakul S. Acute respiratory illness in patients with COPD and the effectiveness of influenza vaccination: a randomized controlled study. Chest 2004;125:2011-2020. Rovida F, Percivalle E, Zavattoni M, et al. Monoclonal antibodies versus reverse transcription-PCR for detection of respiratory viruses in a patient population with respiratory tract infections admitted to hospital. J Med Virol 2005;75:336-347. Seemungal T, Harper-Owen R, Bhowmik A, et al. Respiratory viruses, symptoms, and inflammatory markers in acute exacerbations and stable chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2001;164:1618-1623. Borg I, Rohde G, Loseke S, et al. Evaluation of a quantitative real-time PCR for the detection of respiratory syncytial virus in pulmonary diseases. Eur Respir J 2003;21:944-951. Madhi SA, Klugman KP. A role for Streptococcus pneumoniae in virus-associated pneumonia. Nat Med 2004;10:811-813. Welliver RC. Respiratory syncytial virus infection: therapy and prevention. Paediatr Respir Rev 2004;5:Suppl A:S127-S133. Maggon K, Barik S. New drugs and treatment for respiratory syncytial virus. Rev Med Virol 2004;14:149-168. Fenton C, Scott LJ, Plosker GL. Palivizumab: a review of its use as prophylaxis for serious respiratory syncytial virus infection. Paediatr Drugs 2004;6:177-197. Polack FP, Karron RA. The future of respiratory syncytial virus vaccine development. Pediatr Infect Dis J 2004;23:Suppl:S65-S73. Durbin AP, Karron RA. Progress in the development of respiratory syncytial virus and parainfluenza virus vaccines. Clin Infect Dis 2003;37:1668-1677....查看详细 (10826字节)

☉ 11325817:Case 13-2005 — A 48-Year-Old Man with Weakness of the Limbs and Multiple Tumors of Spinal Nerves
Presentation of Case A 48-year-old, right-handed man was evaluated in the neurology clinic of this hospital because of weakness of his arms and legs. When the patient was 18 years of age, a mass on the right side of his neck developed; a biopsy was performed at another hospital, and he was told he had von Recklinghausen's neurofibromatosis. At 45 years of age, pain and weakness in his left leg developed. A radiograph of the left knee performed elsewhere showed what were described as tumors, and he was referred to an orthopedist at this hospital. Magnetic resonance imaging (MRI) showed an enhancing lesion, 2 cm in diameter, on the sciatic nerve, extending from the ischial tuberosity to the deep peroneal nerve. Physical therapy was administered for the next 10 months, but the pain persisted. A repeated MRI study showed that the thickening of the sciatic nerve involved both the peroneal and tibial branches, extended to the lowest level in the images, and had increased in diameter to 3.6 cm. Three months later, increased pain and a foot drop on the left developed; MRI scanning of the brain and the cervical, thoracic, and lumbar spine performed elsewhere showed no abnormalities of the brain, but there were bilateral enhancing lesions in all cervical neural foramina, with cord compression at C1–2, C2–3, and C4–5 and bilateral rounded nonenhancing lesions in the neural foramina of the thoracic and lumbar spine. Treatment with gabapentin was begun. During the following year, the patient began using a four-point cane and an orthosis for his left foot, and weakness developed in the right leg. He fell on numerous occasions. He began to notice alternating pallor and redness in his feet. An eye examination documented no sign of Lisch nodules. Weakness developed in the left arm and subsequently in the right arm. About one year after starting treatment with gabapentin, the patient was referred to the neurosurgical clinic at this hospital. An MRI of the brain showed no abnormalities. An MRI of the cervical spine showed bilateral enhancing tumors at each level. At the C1–2 level, the cord was compressed from both sides. At the C4–5 level, the cord was displaced into the right canal and indented. An MRI of the thoracic and lumbar spine showed expanded nerve roots bilaterally at every level without cord compression; moderate stenosis of the canal was seen at the L4–5 level. A computed tomographic (CT) scan of the abdominal area showed multiple tumors involving the pelvic and paraspinal nerves and multiple subcutaneous masses. The patient was then referred to the neurology clinic. He characterized his primary problem as weakness, and he also had pain, primarily in his left leg, that was worse with activity. He had no problems with bowel or bladder control and no back pain, headaches, or vision problems. He did not drink or smoke and had been unemployed for four years. His medications were sertraline and gabapentin. The patient's mother died at 87 years of age of lymphoma and his father at 47 years of age of smoking-related emphysema. His mother had had a lump on the back of her neck; he did not recall either parent having skin lesions. His brother was alive at 46 years of age with liver cancer and multiple sclerosis; his sister had died suddenly at the age of 39, and the patient did not know the cause. He did not recall either sibling having skin lesions. His sister's son was said to have neurofibromatosis. The patient was married and had one son, who was well. He was alert and answered questions clearly. There were no dysmorphic features. The vital signs were normal. Both hands and feet were reddened and cold at the beginning of the visit; by the end of the visit, the patient's feet were deep red up to the middle of the tibia. Examination of the skin under ambient light and with a Wood's lamp revealed two café-au-lait macules greater than 1.5 cm in diameter, one on the left lower part of the abdomen and another on the inner aspect of the left buttock. A single, raised, purple cutaneous lesion, 1 cm in diameter, was present on the left side of the chest. There was no axial or inguinal freckling. Multiple subcutaneous tumors were visible throughout the body. The left leg was slightly thicker than the right. An examination of the head, neck, chest, and abdomen revealed no abnormalities. On neurologic examination, the patient's gait was slow and shuffling, and he walked bent at the waist. The cranial-nerve function was normal. On motor examination, strength in both arms was 4/5 with bilateral pronator drift. Fine hand–motor coordination was intact. Motor examination of his legs and feet showed bilateral increased tone with contractures at both heel cords. The right foot was held in a turned-in position. The strength was 4/5 in the right leg and 3/5 in the left leg, with decreased muscle mass in the left leg and left foot drop. Brachioradialis reflexes were 2+ and symmetric in the upper extremities, but on the right side there was spread into the biceps. The Hoffmann's sign was positive on the left and negative on the right. Palmomental reflexes were negative bilaterally. Knee and ankle reflexes were 3+. The Babinski reflex on the right was unreactive and on the left turned upward. The results of routine laboratory tests were normal. Two weeks later, laminectomy of C3–6, with resection of bilateral C2, right C3, and left C5 tumors, was performed, as was fusion of the cervical spine. On pathological examination, all tumors were neurofibromas. Three months later, the patient's pain had diminished and his gait had improved; he was able to walk up a full flight of stairs at home and used a single-point cane only when outside. A new right foot drop had developed. Muscle strength in all extremities was 5/5 except for the ankle flexors, which were 4/5, and he was unable to flex either great toe upward. Muscle tone was slightly increased in the lower extremities, but less so than it had been at the first visit. Three months after the patient's evaluation, his sister's son was also evaluated in the neurology clinic. He was a 29-year-old, right-handed man who had had flat, pigmented lesions on his skin as a teenager. When he was 19 years of age, a subcutaneous nodule appeared on his right shoulder; over the years, more nodules developed, one of which, on his left lower back, became painful. The painful nodule was removed, and pathological examination disclosed a neurofibroma. He had had weakness of his left leg when climbing stairs for three months before his evaluation. He had no other neurologic or physical symptoms. The nephew thought his mother had had what he described as "brown birthmarks." At 39 years of age, she had fallen backward and lost consciousness; a craniotomy was performed at another hospital, but she died three days later. An autopsy reported the cause of death as blunt trauma to the head, with epidural, subdural, and subarachnoid hemorrhage. No skin lesions or nerve tumors were noted. His maternal half-brother and half-sister each had one brown skin lesion. His father was well. Examination of the nephew's skin under ambient light showed freckles in the inguinal regions but not in the axillae. Multiple café-au-lait macules were present, many greater than 1.5 cm in diameter. There were multiple palpable subcutaneous nodules, two of which were painful, on the left leg and left shoulder. There were no cutaneous nodules. The results of a detailed neurologic examination revealed no abnormalities. Diagnostic tests were performed on both the patient and his nephew. Differential Diagnosis Dr. Bruce R. Korf: This clinical history poses two major questions. First, what accounts for this man's weakness, both before and after his surgery? Second, what is his underlying diagnosis and how is his condition related to that in his nephew? May we review the MRIs? Dr. John W. Henson: MRI scans were obtained through the spine, the lumbosacral plexus, and the brain before and after the administration of gadolinium. Parasagittal images revealed large masses along the courses of multiple, bilateral cervical nerve roots (Figure 1A). On axial images through the C2 vertebral body, these lesions had mild heterogeneity of signal intensity. A focus of T2-weighted hypointensity was present within the lateral aspect of the right C2 paraspinal mass lesion, forming a so-called "target sign" (Figure 1B). Heterogeneous gadolinium enhancement was seen. The tumors produced severe compression of the cervical spinal cord at the C2 level and extended laterally into the brachial plexus. There was mild enlargement of thoracic spinal nerve roots. Coronal fast spin-echo inversion-recovery sequences revealed masses along the courses of the lumbar nerve roots and lumbosacral plexus, with extensions along both sciatic nerves (Figure 1C). Figure 1. Neuroimaging Studies Showing Multiple Peripheral Nerve Tumors. A fast spin–echo (FSE) T2-weighted image in the sagittal plane from the cervical spine revealed the presence of multiple mass lesions (arrows) along the cervical spinal roots (Panel A). An axial FSE T2-weighted image at the level of the second cervical vertebral body (Panel B) showed the presence of cervical spinal cord compression by mass lesions along bilateral spinal nerve roots. The tumors were hyperintense on T2-weighted images and had a focal region of low signal consistent with the so-called "target sign" (arrow) and had heterogeneous enhancement after the administration of gadolinium. A coronal FSE inversion recovery image through the lumbosacral plexus (Panel C) showed plexiform mass lesions and diffuse enlargement of the sciatic nerves (arrows). Multiple neurogenic tumors can be either neurofibromas or schwannomas.1,2 On imaging studies, neurofibromas usually show heterogeneous enhancement, whereas schwannomas usually enhance homogeneously. Approximately half of neurofibromas show the target sign, which is a central region of lower intensity surrounded by higher intensity on T2-weighted images. This is more common in plexiform neurofibromas but can rarely be present in schwannomas. Neurofibromas are more likely to produce diffuse or plexiform lesions than are schwannomas. Imaging of the patient's brain revealed no sign of lesions that are considered typical of neurofibromatosis type 1, such as glioma of the optic pathway, foci of abnormal T2-weighted hyperintensity within the brain, plexiform neurofibromas of the ophthalmic division of the fifth cranial nerves, or dysplasia of the greater wing of the sphenoid bone. There was no evidence of nodular enhancement along the courses of the eighth cranial nerves to suggest the presence of vestibular schwannomas, as are seen in neurofibromatosis type 2. The interpretation of the neuroradiologic images was that there were multiple neurofibromas, with a plexiform pattern of involvement. Dr. Korf: This patient was given a diagnosis of von Recklinghausen's neurofibromatosis at 18 years of age. That was at least 30 years ago, before the formulation of diagnostic criteria for neurofibromatosis type 1 and neurofibromatosis type 2 in 1987.3 These two forms of neurofibromatosis were not always clearly distinguished before 1987, and we do not know whether any other signs of either type were present in this patient. His current symptoms of pain and weakness began three years before his evaluation here. Review of the first MRI obtained of his left leg reveals enlargement of the sciatic nerve, with an appearance typical of neurofibroma. A neurofibroma is a benign neoplasm involving various cellular elements of the nerve sheath. Neurofibromas may occur as focal growths along a nerve or at a nerve ending in the skin, or they can extend along a length of nerve and involve multiple fascicles of a larger nerve, forming a plexiform neurofibroma.4 Plexiform neurofibromas can be asymptomatic, but pain, weakness, and sensory dysfunction can occur, particularly if the nerve enlargement leads to compression. Subsequent MRI scanning revealed much more widespread disease, with multiple tumors of the cervical nerve roots, several of which were compressing the spinal cord. Weakness increased over a period of about a year and spread to include his right leg and arm. A neurologic examination revealed signs of both upper- and lower-motor-neuron dysfunction. The foot drop on the left suggests a peroneal neuropathy. Increased tone, brisk deep-tendon reflexes, and a positive Hoffmann's sign and Babinski's sign suggest cord compression. Vasomotor dysfunction in the lower part of the legs may be further signs of peripheral-nerve dysfunction. The patient had marked improvement in strength after resection of several cervical tumors, but a newly developed foot drop on the right suggests peroneal-nerve dysfunction on that side. His pain and weakness are likely to be the combined results of spinal cord compression at multiple levels and peripheral-nerve dysfunction in the legs, probably due to compression of massively enlarged nerves. Classification and Diagnosis of Neurofibromatosis This patient has a disorder that leads to multiple tumors of the peripheral-nerve sheath. Some form of neurofibromatosis would seem most likely. There are two widely recognized forms of neurofibromatosis, type 1 and type 2 (Table 1). Within the past decade, an additional entity referred to as schwannomatosis5 has been added to this short list, but since the tumors in this patient were neurofibromas, not schwannomas, we can exclude this condition. Neurofibromatosis type 2 is also unlikely. Although neurofibromas can occur in persons with neurofibromatosis type 2, schwannomas are far more common. The hallmark lesion, the vestibular schwannoma, was not present on cranial MRI studies of this patient. Table 1. Classification of the Forms of Neurofibromatosis. The presence of multiple neurofibromas in this patient fulfills one criterion for neurofibromatosis type 1 (Table 2),3,6 but at least two are required to establish the diagnosis. He had two café-au-lait spots, not the requisite six, and did not have axillary or inguinal freckles, Lisch nodules (iris hamartomas that are found in most adults with neurofibromatosis type 1 and that are highly specific signs of the disorder), skeletal dysplasia, or optic glioma. There was no definitive diagnosis of neurofibromatosis type 1 in a first-degree relative. Table 2. Diagnostic Criteria for Neurofibromatosis Type 1. There are variant forms of neurofibromatosis (Table 3). Familial multiple café-au-lait spots7 and Watson's syndrome8 clearly do not fit this patient's history. Patients with segmental neurofibromatosis have symptoms confined to a particular region of the body.9 This localized form of the disease is attributable to somatic mosaicism for a neurofibromatosis type 1 mutation, at least in some cases. The disease in the patient under discussion was too widespread to be described as segmental. Table 3. Variant Forms of Neurofibromatosis Type 1. Ten patients10 have been described who had generalized neurofibromas but who did not display other features of neurofibromatosis type 1. In this group, both isolated and plexiform neurofibromas were seen, including spinal-nerve-root tumors, some of which caused cord compression. Some patients had dermal neurofibromas, whereas others had firm subcutaneous masses similar to those reported in this patient. It is unclear whether any of the patients in the report had as many tumors as the patient in this case. The other relevant variant of neurofibromatosis is familial spinal neurofibromatosis.11,12,13 Patients with this condition have neurofibromas that originate from spinal nerve roots, often at every level, similar to the findings in the patient under discussion. Cord compression occurs commonly. Most patients have multiple café-au-lait spots, some have iris Lisch nodules, and skin-fold freckling is variable. Most patients have disease with features that fulfill the diagnostic criteria for neurofibromatosis type 1. However, typical dermal neurofibromas are usually absent in these patients, even in adulthood, when this tumor is apt to be found in patients with classic neurofibromatosis type 1. Mutations in the NF1 gene have been identified in several families.11,12,14 The patient in this case fits somewhere between these two entities — he has spinal tumors similar to those seen in patients with familial spinal neurofibromatosis, but he lacks multiple café-au-lait spots. I am inclined to classify him with the patients who have familial spinal neurofibromatosis because of his spinal tumors. Some patients with spinal neurofibromatosis have been described as having peripheral tumors.11 I suspect that the two entities of familial spinal neurofibromatosis and generalized neurofibromatosis without other signs may represent a spectrum of manifestations of one disease. In most patients — but not all — with spinal neurofibromatosis, findings have shown linkage to the NF1 locus or there are NF1 gene mutations, whereas molecular studies of individual patients with isolated generalized neurofibromas have not been reported. Familial Spinal Neurofibromatosis Does this patient have a familial disorder? His nephew is said to have "many" café-au-lait macules and had inguinal but not axillary freckling; both are usually seen in adults with neurofibromatosis type 1. The nephew had multiple painful subcutaneous neurofibromas, like the patient, and no dermal tumors. We do not know if he had spinal tumors, but he had weakness of the left leg. I believe that the nephew had the same disorder as our patient and that he would prove to have spinal neurofibromas if MRI were performed. Although neurofibromatosis is a highly variable disorder, penetrance is complete, so I would not expect to see a skipped generation. Did the patient's sister, the mother of the nephew, also have this disorder? She died suddenly, reportedly with evidence of blunt head trauma. She is also said to have had "brown spots." Thus, it is possible that she also had neurofibromatosis. If the patient and his sister both had neurofibromatosis, one parent should also have been affected. The patient's mother is said to have had a "neck mass." Either parent could have been affected without the disease ever being diagnosed, given the paucity of externally visible signs in this patient. Alternatively, one of the patient's parents could have had mosaicism for a mutation that could have been transmitted to two children without affecting the parent, as has been documented for at least one family with neurofibromatosis type 1.15 In respect to this patient and his nephew, it is possible that each has a form of neurofibromatosis due to a distinct and independent gene mutation. Multiple different NF1 gene mutations in different members of the same extended family have been reported.16 I believe that this is unlikely in this case, since both the patient and his nephew have a similar disorder with a paucity of cutaneous signs and many subcutaneous and deep neurofibromas. Genetic Testing in Neurofibromatosis The patient and his nephew underwent a "diagnostic test." I do not believe that much more would have been learned from pathological examination of tumors. It would be valuable to obtain an MRI of the spine in the nephew, but nothing would be learned from additional MRI studies of the patient. The diagnostic test was therefore probably a molecular genetic test of the NF1 gene, searching for a gene mutation. Until recently, there was no practical clinical diagnostic test for neurofibromatosis type 1. The gene is large (60 exons) and mutations are widely scattered in the gene, so that almost no two families with neurofibromatosis type 1 share the same mutation.17 This disorder has a high mutation rate, and hundreds of distinct mutations have been reported. There are some recurrent mutations, but no "hot spots" to guide clinical testing. There are no major genotype–phenotype correlations, except that patients who lack the gene entirely tend to have a severe phenotype with early onset and large numbers of neurofibromas, developmental delay, and dysmorphic facial appearance.18 Mutation analysis for neurofibromatosis type 1 is now available for clinical testing, with the use of a set of complementary techniques to find the various types of mutation, including deletion of the entire gene, small insertions or deletions that cause a frame shift, single-base changes that lead to a stop codon or amino acid substitution, and mutations that alter RNA splicing.19 Most of the mutations lead to premature termination of peptide synthesis and hence obliterate the function of the gene product. The fact that the mutations result in loss of function is compatible with the notion that NF1 functions as a tumor-suppressor gene in the pathogenesis of neurofibromas, requiring loss-of-function mutations in both alleles to produce a tumor. Mutation testing has been performed in several patients with familial spinal neurofibromatosis (Figure 2). Of nine mutations reported, four are amino acid substitutions, which is remarkable since not more than 10 percent of all NF1 mutations have been found to be missense changes. Three are splicing mutations and only two generate stop codons, one by frame shift and one by nonsense mutation.11,12,14,20 Figure 2. Location of NF1 Gene Mutations Reported in Familial Spinal Neurofibromatosis. The GAP (GTPase activating protein)-related domain, where the mutations occur, is labeled according to the source where the mutation was described. IVS5–2AG, L920P, P2200A, and S2698X were described by Kluwe et al.11; 8042insA by Ars et al.12; L357P and IVS39+3AG by Messiaen et al.14; and IVS31–5AG and L2067P by Kaufmann et al.20 Diagnosis This patient had a mixed upper-motor-neuron dysfunction due to cord compression at multiple levels and lower-motor-neuron disease due to nerve compression. I believe the underlying cause was the presence of multiple spinal and plexiform neurofibromas caused by a variant of neurofibromatosis type 1 similar to familial spinal neurofibromatosis. I believe that both the patient and his nephew have the same disorder, and that both will be shown to have an NF1 gene mutation, probably a splicing defect or missense mutation. Dr. Nancy Lee Harris (Pathology): Dr. MacCollin, can you give us your clinical impressions? Dr. Mia MacCollin (Neurology): At the time the patient was first evaluated in the neurofibromatosis clinic, we who saw him believed that he had the rare syndrome of multiple isolated neurofibromas as described by Blakley et al.10 We thought that the nephew's illness was due to the relatively common occurrence of a new mutation in the NF1 gene and that his disease was genetically unrelated to his uncle's rare syndrome. Clinical Diagnosis Multiple isolated neurofibromas. Dr. Bruce R. Korf's Diagnosis Neurofibromatosis type 1 variant, similar to familial spinal neurofibromatosis. Pathological Discussion Dr. Harris: Dr. Smith, could you describe your operative findings? Dr. Edward R. Smith (Surgery, Children's Hospital, Boston): A multilevel cervical laminectomy was performed, which revealed very large extradural tumors at C2 that were touching at midline. These tumors were resected, as was another extradural mass at C3. The dura was opened, revealing a sizable C5 tumor that was completely displacing the spinal cord to one side; it was removed. At the completion of the operation, despite the presence of abundant space in the canal, the spinal cord retained the impressive deformation shown on the preoperative radiographs, with a thin, effaced high cervical cord. The dura was closed, and a multilevel fusion with a lateral mass screw construct was performed. Dr. Anat Stemmer-Rachamimov: The tumors were hypocellular, with myxoid stroma, a heterogeneous cell population of round cells and wavy cells, and entrapped large nerve bundles (Figure 3A). Only scattered Schwann cells, which are the neoplastic cells, were positive for S100 protein (Figure 3B), and neurofilament immunostaining highlighted enlarged nerve bundles and dispersed axons within the tumors (Figure 3C). The pathological diagnosis was multiple plexiform spinal-nerve-root neurofibromas, with no malignant transformation. The nephew's specimen was also a neurofibroma. Figure 3. Specimens from Spinal-Nerve-Root Tumors. The tumor is composed of spindled and round cells with entrapped axons (Panel A; hematoxylin and eosin). With immunostaining for S100 protein (Panel B), only scattered neoplastic Schwann cells are stained. The other cells are non-neoplastic stromal and nerve cells. Enlarged nerve bundles and dispersed axons within the tumors are highlighted with neurofilament immunostaining (Panel C). Multiple spinal neurofibromas at autopsy (Panel D, from another patient) show markedly enlarged spinal nerve roots, seen from the thoracic cavity, which are symmetrically involved by plexiform neurofibromas. (Autopsy photograph courtesy of Dr. Matthew Frosch, Department of Pathology, MGH.) Patients with multiple spinal neurofibromatosis often have spinal tumors that are distributed symmetrically and involve many or all spinal roots (Figure 3D).11 In the absence of other clinical features of neurofibromatosis type 1, the pathological distinction between schwannomas and neurofibromas is important, because multiple spinal-root-tumors may be seen in schwannomatosis and neurofibromatosis type 2.21 Schwannomas are also tumors of Schwann cells, but they lack the heterogeneous cell population found in neurofibromas. This distinction may be difficult to make when schwannomas have prominent myxoid changes that mimic the histological appearance of neurofibromas. In these cases, it is helpful to find areas with classic schwannoma features, or to establish by S100 immunostaining or electron microscopy that only a subgroup of cells are Schwann cells. Dr. Harris: Dr. MacCollin, will you tell us about the additional diagnostic testing? Dr. MacCollin: A tissue sample from the patient was sent to the laboratory of Dr. Ludwine Messaien at the Center of Medical Genetics, Ghent University Hospital in Belgium. No alterations were found in the NF1 gene by protein-truncation testing. Direct sequencing of the gene revealed an unusual alteration in exon 22 (G3827A, leading to the substitution of glutamine for arginine at residue 1276). This change had previously been detected in a single sample from an unrelated 19-year-old patient with an unusually large load of cutaneous and plexiform neurofibromas. It had also been reported twice22 in a series of 301 sequence variants in the NF1 gene. It occurs at a CpG hypermutatable site that is also involved in the more typical change, C3826T, which causes a nonsense mutation at arginine 1276. The patient's nephew had the same mutation. Subsequent MRI examinations showed that the patient's nephew has multiple spinal nerve root plexiform neurofibromas, without cord compression. We have been unable to analyze the autopsy specimens from the patient's sister. Anatomical Diagnosis Neurofibromatosis type 1, affecting the patient and his nephew, with multiple spinal neurofibromas. Dr. Korf reports having received lecture fees from Pharmacia. Source Information From the Department of Genetics, University of Alabama at Birmingham (B.R.K.); and the Departments of Radiology and Neurology (J.W.H.) and Pathology (A.S.-R.), Massachusetts General Hospital and Harvard Medical School — both in Boston. References Khong PL, Goh WH, Wong VC, Fung CW, Ooi GC. MR imaging of spinal tumors in children with neurofibromatosis 1. AJR Am J Roentgenol 2003;180:413-417. Suh JS, Abenoza P, Galloway HR, Everson LI, Griffiths HJ. Peripheral (extracranial) nerve tumors: correlation of MR imaging and histologic findings. Radiology 1992;183:341-346. Stumpf DA, Alksne JF, Annegers JF, et al. Neurofibromatosis: conference statement: National Institutes of Health Consensus Development Conference. Arch Neurol 1988;45:575-578. Korf BR. Plexiform neurofibromas. Am J Med Genet 1999;89:31-37. MacCollin M, Woodfin W, Kronn D, Short MP. Schwannomatosis: a clinical and pathologic study. Neurology 1996;46:1072-1079. Gutmann DH, Aylsworth A, Carey JC, et al. The diagnostic evaluation and multidisciplinary management of neurofibromatosis 1 and neurofibromatosis 2. JAMA 1997;278:51-57. Arnsmeier SL, Riccardi VM, Paller AS. Familial multiple cafe au lait spots. Arch Dermatol 1994;130:1425-1426. Tassabehji M, Strachan T, Sharland M, et al. Tandem duplication within a neurofibromatosis type 1 (NF1) gene exon in a family with features of Watson syndrome and Noonan syndrome. Am J Hum Genet 1993;53:90-95. Ruggieri M, Huson SM. The clinical and diagnostic implications of mosaicism in the neurofibromatoses. Neurology 2001;56:1433-1443. Blakley P, Louis DN, Short MP, MacCollin M. A clinical study of patients with multiple isolated neurofibromas. J Med Genet 2001;38:485-488. Kluwe L, Tatagiba M, Funsterer C, Mautner VF. NF1 mutations and clinical spectrum in patients with spinal neurofibromas. J Med Genet 2003;40:368-371. Ars E, Kruyer H, Gaona A, et al. A clinical variant of neurofibromatosis type 1: familial spinal neurofibromatosis with a frameshift mutation in the NF1 gene. Am J Hum Genet 1998;62:834-841. Pulst S-M, Riccardi VM, Fain P, Korenberg JR. Familial spinal neurofibromatosis: clinical and DNA linkage analysis. Neurology 1991;41:1923-1927. Messiaen L, Riccardi V, Peltonen J, et al. Independent NF1 mutations in two large families with spinal neurofibromatosis. J Med Genet 2003;40:122-126. Lázaro C, Ravella A, Gaona A, Volpini V, Estivill X. Neurofibromatosis type 1 due to germ-line mosaicism in a clinically normal father. N Engl J Med 1994;331:1403-1407. Upadhyaya M, Majounie E, Thompson P, et al. Three different pathological lesions in the NF1 gene originating de novo in a family with neurofibromatosis type 1. Hum Genet 2003;112:12-17. Castle B, Baser ME, Huson SM, Cooper DN, Upadhyaya M. Evaluation of genotype-phenotype correlations in neurofibromatosis type 1. J Med Genet 2003;40:e109-e109. Leppig KA, Kaplan P, Viskochil D, Weaver M, Ortenberg J, Stephens K. Familial neurofibromatosis 1 microdeletions: cosegregation with distinct facial phenotype and early onset of cutaneous neurofibromata. Am J Med Genet 1997;73:197-204. Messiaen LM, Callens T, Mortier G, et al. Exhaustive mutation analysis of the NF1 gene allows identification of 95% of mutations and reveals a high frequency of unusual splicing defects. Hum Mutat 2000;15:541-555. Kaufmann D, Muller R, Bartelt B, et al. Spinal neurofibromatosis without cafe-au-lait macules in two families with null mutations of the NF1 gene. Am J Hum Genet 2001;69:1395-1400. Evans DGR, Mason S, Huson SM, Ponder M, Harding AE, Strachan T. Spinal and cutaneous schwannomatosis is a variant form of type 2 neurofibromatosis: a clinical and molecular study. J Neurol Neurosurg Psychiatry 1997;62:361-366. Fahsold R, Hoffmeyer S, Mischung C, et al. Minor lesion mutational spectrum of the entire NF1 gene does not explain its high mutability but points to a functional domain upstream of the GAP-related domain. Am J Hum Genet 2000;66:790-818....查看详细 (31735字节)
☉ 11325818:Von Recklinghausen's Disease and Breast Cancer
A 74-year-old woman with a history of von Recklinghausen's disease presented with infiltrating lobular carcinoma of the left breast (T2N0M0 [stage IB], according to the tumor–node–metastasis [TNM] staging system). On physical examination, the patient had innumerable cutaneous neurofibromas (Panels A and B). Of the patient's three children (twin daughters and a son), all had inherited the condition, which is also called neurofibromatosis 1. One of her daughters had died at the age of 12 years from complications of a viral illness, and both her other daughter and her son had died at the age of 38 from cancer. The patient's breast tumor was both estrogen-receptor–positive and progesterone-receptor–positive. She underwent a modified radical mastectomy and was subsequently treated with tamoxifen. During the past three years, there has been no evidence of a recurrence of the tumor, and the patient has had no other complications. Juan G. Posada, M.D. Carl G. Chakmakjian, D.O. Scott and White Memorial Hospital and Clinic Temple, TX 76508...查看详细 (1073字节)
☉ 11325819:Thrombosis of the Cerebral Veins and Sinuses
Thrombosis of the cerebral veins and sinuses is a distinct cerebrovascular disorder that, unlike arterial stroke, most often affects young adults and children. The symptoms and clinical course are highly variable. A teenager who has had recent headaches after starting oral contraception, a woman who has had seizures after delivery in the obstetrical ward, and a comatose man with a dilated pupil in the emergency room all may have sinus thrombosis. The estimated annual incidence is 3 to 4 cases per 1 million population and up to 7 cases per 1 million among children. About 75 percent of the adult patients are women. During the past decade, increased awareness of the diagnosis, improved neuroimaging techniques, and more effective treatment have improved the prognosis. More than 80 percent of all patients now have a good neurologic outcome. This review summarizes recent insights into the pathogenesis of sinus thrombosis, risk factors, and clinical and radiologic diagnosis and discusses the current evidence and controversies about the best treatment. Pathogenesis To understand the symptoms and signs of sinus thrombosis, two different mechanisms should be distinguished: thrombosis of the cerebral veins, with local effects caused by venous obstruction, and thrombosis of the major sinuses (Figure 1), which causes intracranial hypertension. In the majority of patients, these two processes occur simultaneously. Figure 1. Frequency of Thrombosis of the Major Cerebral Veins and Sinuses. The frequencies of thrombosis in the various sinuses are given as percentages and are based on data from the International Study on Cerebral Vein and Dural Sinus Thrombosis.1 In most patients, thrombosis occurs in more than one sinus. The first mechanism, occlusion of the cerebral veins, can cause localized edema of the brain and venous infarction. Pathological examination shows enlarged, swollen veins, edema, ischemic neuronal damage, and petechial hemorrhages (Figure 2). The latter can merge and become large hematomas, which have a characteristic appearance on computed tomographic (CT) scans (Figure 3). Two different kinds of cerebral edema can develop. The first, cytotoxic edema, is caused by ischemia, which damages the energy-dependent cellular membrane pumps, leading to intracellular swelling. The second type, vasogenic edema, is caused by a disruption in the blood–brain barrier and leakage of blood plasma into the interstitial space. Vasogenic edema is reversible if the underlying condition is treated successfully. Magnetic resonance imaging (MRI) has shown that both cytotoxic and vasogenic edema occur in cerebral vein thrombosis.3,4 Figure 2. Postmortem Views of Sinus Thrombosis. Panel A provides a caudal view of the inside of the skull after removal of the brain, with thrombosis of the cortical veins (arrows) evident on both sides of the superior sagittal sinus (not opened), which is also thrombosed. Panel B shows a large hemorrhagic venous infarct in the same patient. Figure 3. CT Imaging of Sinus Thrombosis. A CT scan (Panel A) shows a large infarct in the right parietal lobe (at left in the image) in a patient with sinus thrombosis. The infarct is hemorrhagic (white patches). The falx cerebri is displaced to the left as a result of compression by the infarct. In the CT scan in Panel B, bilateral thalamic edema (dark area in center) has been caused by thrombosis of the straight sinus. In Panel C, an image obtained by CT venography shows reconstruction of the cerebral venous system after the injection of intravenous contrast material and removal of bone voxels.2 This lateral view provides good visibility of the major sinuses, including the straight sinus and the cortical and deep cerebral veins (without thrombosis). The second mechanism is the development of intracranial hypertension as the result of occlusion of the major venous sinuses. Normally, the cerebrospinal fluid is transported from the cerebral ventricles through the subarachnoid spaces at the base and surface of the brain to the arachnoid villi, where it is absorbed and drained into the superior sagittal sinus. Thrombosis of the sinuses leads to increased venous pressure, impaired absorption of cerebrospinal fluid, and consequently, increased intracranial pressure. The obstruction to the drainage of cerebrospinal fluid is located at the end of its transport pathway, and no pressure gradient develops between the subarachnoid spaces at the surface of the brain and the ventricles. Hence, the ventricles do not dilate, and hydrocephalus does not normally complicate sinus thrombosis. About one fifth of patients with sinus thrombosis have intracranial hypertension only, without signs of cortical vein thrombosis.1 Causes and Risk Factors A prothrombotic risk factor or a direct cause is identified in about 85 percent of patients with sinus thrombosis (Table 1). Often, a precipitating factor, such as a head injury or obstetrical delivery, causes sinus thrombosis in a person with a genetically increased risk. During the last trimester of pregnancy and after delivery, the risk of sinus thrombosis is increased.16 The frequency of peripartum and postpartum sinus thrombosis is about 12 cases per 100,000 deliveries, only slightly lower than that of peripartum and postpartum arterial stroke.17 Table 1. Causes of and Risk Factors Associated with Cerebral Venous Sinus Thrombosis. Two case–control studies have shown an increased risk of sinus thrombosis in women who use oral contraceptives,9,23 especially third-generation contraceptives that contain gestodene or desogestrel.26 Additional evidence of an increased risk in women who use oral contraceptives is the change in the sex ratio of cases of sinus thrombosis over time. Until the mid-1970s, men and women were equally affected.27 More recently, there has been a significant female predominance among young adults with sinus thrombosis (70 to 80 percent of cases are in women of childbearing age) but not among children or elderly persons.1,6,28 Laboratory findings support the evidence that oral contraceptives have a prothrombotic effect.29 Trauma and Lumbar Puncture The mechanical causes of sinus thrombosis are head injury, direct injury to the sinuses or the jugular veins — for instance, from jugular catheterization — and neurosurgical procedures. A lumbar puncture can also lead to sinus thrombosis.25 A plausible reason is that low cerebrospinal fluid pressure after a lumbar puncture causes a downward shift of the brain, with traction on the cortical veins and sinuses. Deformation of the venous walls may induce thrombosis. The diagnosis of sinus thrombosis after a lumbar puncture is difficult, because the headache that follows is attributed not to sinus thrombosis but to the lumbar puncture itself.30 However, the headache resulting from lumbar puncture typically disappears when the patient lies down, and it resolves within a few days, whereas the headache in patients with sinus thrombosis does not change with a shift in posture and worsens during the first stage of the disease. Infections Otitis and mastoiditis can be complicated by thrombosis of the adjacent sigmoid and transverse sinuses. If the contralateral transverse sinus is hypoplastic — a frequent anatomical variant — absorption of the cerebrospinal fluid becomes impaired. The resulting intracranial hypertension with accompanying papilledema was formerly known as "otitic hydrocephalus," a classic misnomer, since the ventricles normally are not enlarged in cases of sinus thrombosis. The frequency of infectious sinus thrombosis has declined and varies from 6 to 12 percent in large series of adults with sinus thrombosis.1,5 Higher frequencies of both systemic infections (e.g., neonatal sepsis) and local infections (e.g., otitis) are reported in children.6 A special case is thrombosis of the cavernous sinuses, which is nearly always caused by an infection of the paranasal (ethmoid and sphenoid) sinuses, the orbit, or the face. Clinical Manifestations The most frequent but least specific symptom of sinus thrombosis is severe headache, which is present in more than 90 percent of adult patients. It usually increases gradually over a couple of days but can also start in a split second, mimicking a subarachnoid hemorrhage.31 Cerebral lesions and neurologic signs develop in half of patients with sinus thrombosis. Characteristic, but rare, is the occurrence of unilateral hemispheric symptoms such as hemiparesis or aphasia, followed within days by symptoms from the other hemisphere; these are caused by the development of cortical lesions on both sides of the superior sagittal sinus. Seizures occur in about 40 percent of patients, a far higher percentage than in patients with arterial stroke. Seizures are limited and focal in 50 percent of these patients but may generalize to a life-threatening status epilepticus. Thrombosis of the deep venous system — the straight sinus and its branches — causes centrally located, often bilateral thalamic lesions (Figure 3), with behavioral symptoms such as delirium, amnesia, and mutism, which can be the only manifestation of sinus thrombosis.32 If large unilateral infarcts or hemorrhages compress the diencephalon and brain stem, patients may become comatose or die from cerebral herniation if untreated. Other causes of coma are involvement of the thalamus and generalized seizures. Infectious cavernous sinus thrombosis is characterized by headache, fever, and eye symptoms such as periorbital edema, proptosis, chemosis, and paralysis of eye movements due to involvement of the oculomotor, abducent, or trochlear nerves. Patients with isolated intracranial hypertension have headache but no other neurologic symptoms, with the exception of diplopia due to involvement of the sixth nerve when the intracranial pressure is quite high. Funduscopic examination will reveal papilledema. Severe papilledema can cause transient visual impairments, and even permanent blindness, if left untreated. Diagnosis Although the clinical presentation is highly variable, the diagnosis should be considered in young and middle-aged patients with recent unusual headache or with stroke-like symptoms in the absence of the usual vascular risk factors, in patients with intracranial hypertension, and in patients with CT evidence of hemorrhagic infarcts, especially if the infarcts are multiple and not confined to the arterial vascular territories. The average delay from the onset of symptoms to the diagnosis is seven days.1 The most sensitive examination technique is MRI in combination with magnetic resonance venography.33,34 T1-weighted and T2-weighted MRI will show a hyperintense signal from the thrombosed sinuses (Figure 4). The characteristics of the signal depend on the age of the thrombus and are isointense on T1-weighted images during the first five days and after one month.34,35 The combination of an abnormal signal in a sinus and a corresponding absence of flow on magnetic resonance venography confirms the diagnosis of thrombosis, but expert radiologic judgment is required to avoid diagnostic and technical pitfalls.36 If MRI is not readily available, CT scanning is a useful technique for the initial examination, to rule out other acute cerebral disorders and to show venous infarcts or hemorrhages, but its results can also be entirely normal. High-resolution CT equipment may show the thrombus as a hyperintense signal in a sinus or even in the cortical veins (the "cord sign"). CT venography is a promising new technique for creating images of the cerebral venous system (Figure 3).2 If the diagnosis is still uncertain after MRI or CT venography has been performed, cerebral angiography may be indicated. Angiography provides better details of the cerebral veins and hence is useful in the diagnosis of rare cases of isolated thrombosis of the cortical veins without sinus thrombosis.34 Angiography also shows dilated and tortuous ("corkscrew") veins, which are evidence of thrombosis downstream in the sinuses (Figure 5). Interpretation of the angiograms can be difficult because of anatomical variations such as a unilaterally hypoplastic or absent transverse sinus.5 Figure 4. MRI of Sinus Thrombosis. In Panel A, a T1-weighted MRI scan obtained with the spin–echo technique provides a sagittal view of a hyperintense signal in the thrombosed superior sagittal sinus (arrows). In Panel B, a magnetic resonance venogram obtained without the administration of contrast material reveals the absence of a signal in the superior sagittal sinus (upper arrows) and a normal flow signal in the transverse and sigmoid sinuses (lower arrow) as well as in a number of veins. Figure 5. Angiographic Image (Venous Phase) of Sinus Thrombosis. In this venous phase of a digital-subtraction angiogram that was obtained after the injection of contrast material into the right internal carotid artery (left lateral view), a large part of the superior sagittal sinus (arrows at upper perimeter) and some cortical veins (near 2) do not fill with contrast material. The sigmoid and transverse sinuses are normal. There is increased contrast in the frontal cortical veins (near 1) and increased filling of the superior anastomotic vein (Trolard's vein; lower arrow). Treatment General Measures The combination of acutely increased intracranial pressure and large venous infarcts is dangerous, and patients may die within hours from cerebral herniation. Impaired consciousness and cerebral hemorrhage are associated with a poor outcome,1,37 but even patients with these manifestations can make a remarkable recovery. The priority of treatment in the acute phase is to stabilize the patient's condition and to prevent or reverse cerebral herniation. This may require the administration of intravenous mannitol, surgical removal of the hemorrhagic infarct, or decompressive hemicraniectomy.38 It is not known whether the administration of corticosteroids in the acute phase improves outcome. Possible causes of sinus thrombosis, such as infections, should be searched for and treated. Anticoagulation The most obvious treatment option is anticoagulation with heparin to arrest the thrombotic process and to prevent pulmonary embolism, which may complicate sinus thrombosis.39 However, anticoagulant treatment has raised much controversy because of the tendency of venous infarcts to become hemorrhagic: about 40 percent of all patients with sinus thrombosis have a hemorrhagic infarct even before anticoagulant treatment is started.1 The effect of anticoagulant treatment has been examined in three small, randomized clinical trials.40,41,42 The first trial compared the effect of intravenous heparin with that of placebo and was stopped after only 10 patients had been included in each treatment group, because an interim analysis showed a significant benefit with heparin, according to the investigators.40 A repeated analysis, which was based on the usual scales of stroke outcome, did not show a statistically significant difference between the effect of heparin and that of placebo.43 Also, the average delay of four weeks from the onset of symptoms to the beginning of treatment was exceptionally long. The second study compared the effect of fixed high-dose, subcutaneous nadroparin with that of placebo in 60 patients and found no statistically significant difference.41 This study was criticized for an imbalance at baseline, which may have favored the placebo group.44 The third study compared the effect of intravenous unfractionated heparin with that of placebo in 57 women from India who had puerperal sinus thrombosis but in whom the diagnosis had not been confirmed by MRI or angiography.42 All three trials showed a nonsignificant benefit of anticoagulant treatment as compared with placebo. In the two trials that involved adequate diagnostic imaging, 23 percent of the patients given placebo had poor outcomes (death or functional dependency), as compared with 10 percent of the group that received anticoagulant therapy. A meta-analysis of these studies showed a nonsignificant reduction in the pooled relative risk of death or dependency of 0.46 (95 percent confidence interval, 0.16 to 1.31).43 A new trial with enough power to demonstrate a similar effect of treatment would require the recruitment of 300 patients. With a rare disease such as sinus thrombosis, this would be challenging but feasible. In the absence of hard evidence from trials, circumstantial evidence can help in choosing the best treatment strategy. The main reason to avoid heparin in the treatment of sinus thrombosis has been concern about its safety. Although the trials mentioned above included patients who had had hemorrhagic infarcts before treatment, no increased or new cerebral hemorrhages developed after treatment with heparin. Moreover, two cases of pulmonary embolism occurred in the placebo groups. Most neurologists now start treatment with heparin as soon as the diagnosis is confirmed, even in the presence of hemorrhagic infarcts. This treatment was applied to more than 80 percent of the 624 patients in a recent prospective study.1 In this study, 79 percent of the patients recovered, 8 percent had minor handicaps, 5 percent were severely handicapped, and 8 percent died. There have been no studies that compared the effect of fractionated heparin with that of unfractionated heparin in the treatment of sinus thrombosis. In the treatment of thrombosis of the leg veins, fixed high-dose, subcutaneous heparin of low molecular weight causes less major bleeding than does intravenous heparin and has similar antithrombotic efficacy.45 The optimal duration of oral anticoagulant treatment after the acute phase is unknown. Recurrent sinus thrombosis occurs in 2 percent of patients, and about 4 percent of patients have an extracranial thrombotic event within one year.1 Usually, vitamin K antagonists are given for six months after a first episode of sinus thrombosis, or longer in the presence of predisposing factors, with a target international normalized ratio of 2.5. Thrombolysis Endovascular thrombolysis can be attempted with the administration of a thrombolytic enzyme, usually urokinase, into the sinus, sometimes in combination with mechanical thrombo-aspiration. Published reports are limited to case reports and uncontrolled studies, from which it is impossible to conclude that the results associated with endovascular thrombolysis are superior to those with systemic heparin.46 Until better evidence is available, endovascular thrombolysis may be applied at centers where the staff have experience in interventional radiology, and this treatment method should be restricted to patients with a poor prognosis. A randomized trial is needed to compare the effect of heparin with that of endovascular thrombolysis in high-risk patients. Intracranial Hypertension In patients who have symptoms of chronic intracranial hypertension only, the first priority is to rule out a space-occupying process and to investigate whether sinus thrombosis is indeed the cause. If there are no contraindications, such as large infarcts or hemorrhages, a lumbar puncture is then performed to measure the cerebrospinal fluid pressure. This is also the start of treatment, the objective of which is to lower the intracranial pressure, to relieve headache, and to reduce papilledema. Oral acetazolamide (500 to 1000 mg daily) may reduce the intracranial pressure. Often, if effective and tolerated, this agent must be continued for weeks to months, as demonstrated among patients with idiopathic intracranial hypertension.47 If repeated lumbar punctures and treatment with acetazolamide do not control the intracranial pressure within about two weeks, surgical drainage of the cerebrospinal fluid is indicated, usually by a lumboperitoneal shunt. If the visual fields deteriorate, fenestration of the optic-nerve sheet should be considered.48 Both of these procedures are associated with complications, and it is unknown which procedure yields the best long-term results. In summary, important advances have been made in our understanding of the pathophysiology of sinus thrombosis. Sinus thrombosis remains a diagnostic challenge and a potentially disabling or lethal disease, but improved diagnosis and treatment now result in an excellent outcome for most patients. I am indebted to Marinus Vermeulen and Wouter Wieling for their comments on early versions of the manuscript, to Dirk Troost for providing Figure 2, and to Charles B.L.M. Majoie for his help with Figures 3, 4, and 5. Source Information From the Department of Neurology, Academic Medical Center, University of Amsterdam, Amsterdam. Address reprint requests to Dr. Stam at the Department of Neurology, Academic Medical Center, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, the Netherlands, or at j.stam@amc.uva.nl. References Ferro JM, Canhao P, Stam J, Bousser MG, Barinagarrementeria F. Prognosis of cerebral vein and dural sinus thrombosis: results of the International Study on Cerebral Vein and Dural Sinus Thrombosis (ISCVT). Stroke 2004;35:664-670. Majoie CB, van Straten M, Venema HW, den Heeten GJ. Multisection CT venography of the dural sinuses and cerebral veins by using matched mask bone elimination. AJNR Am J Neuroradiol 2004;25:787-791. Corvol JC, Oppenheim C, Manai R, et al. Diffusion-weighted magnetic resonance imaging in a case of cerebral venous thrombosis. Stroke 1998;29:2649-2652. Yoshikawa T, Abe O, Tsuchiya K, et al. Diffusion-weighted magnetic resonance imaging of dural sinus thrombosis. Neuroradiology 2002;44:481-488. Bousser M-G, Ross Russell RW. Cerebral venous thrombosis. London: W.B. Saunders, 1997. deVeber G, Andrew M. Cerebral sinovenous thrombosis in children. N Engl J Med 2001;345:417-423. Deschiens MA, Conard J, Horellou MH, et al. Coagulation studies, factor V Leiden, and anticardiolipin antibodies in 40 cases of cerebral venous thrombosis. Stroke 1996;27:1724-1730. Enevoldson TP, Russell RW. Cerebral venous thrombosis: new causes for an old syndrome? Q J Med 1990;77:1255-1275. Martinelli I, Sacchi E, Landi G, Taioli E, Duca F, Mannucci PM. High risk of cerebral-vein thrombosis in carriers of a prothrombin-gene mutation and in users of oral contraceptives. N Engl J Med 1998;338:1793-1797. Ludemann P, Nabavi DG, Junker R, et al. Factor V Leiden mutation is a risk factor for cerebral venous thrombosis: a case-control study of 55 patients. Stroke 1998;29:2507-2510. Weih M, Junge-Hulsing J, Mehraein S, Ziemer S, Einhaupl KM. Hereditare Thrombophilien bei ischamischem Schlaganfall und Sinusvenenthrombosen: Diagnostik, Therapie und Meta-Analyse. Nervenarzt 2000;71:936-945. Reuner KH, Ruf A, Grau A, et al. Prothrombin gene G20210A transition is a risk factor for cerebral venous thrombosis. Stroke 1998;29:1765-1769. Hillier CE, Collins PW, Bowen DJ, Bowley S, Wiles CM. Inherited prothrombotic risk factors and cerebral venous thrombosis. QJM 1998;91:677-680. Cantu C, Alonso E, Jara A, et al. Hyperhomocysteinemia, low folate and vitamin B12 concentrations, and methylene tetrahydrofolate reductase mutation in cerebral venous thrombosis. Stroke 2004;35:1790-1794. Carhuapoma JR, Mitsias P, Levine SR. Cerebral venous thrombosis and anticardiolipin antibodies. Stroke 1997;28:2363-2369. Cantu C, Barinagarrementeria F. Cerebral venous thrombosis associated with pregnancy and puerperium: review of 67 cases. Stroke 1993;24:1880-1884. Lanska DJ, Kryscio RJ. Risk factors for peripartum and postpartum stroke and intracranial venous thrombosis. Stroke 2000;31:1274-1282. Vidailhet M, Piette JC, Wechsler B, Bousser MG, Brunet P. Cerebral venous thrombosis in systemic lupus erythematosus. Stroke 1990;21:1226-1231. Daif A, Awada A, al-Rajeh S, et al. Cerebral venous thrombosis in adults: a study of 40 cases from Saudi Arabia. Stroke 1995;26:1193-1195. Farah S, Al-Shubaili A, Montaser A, et al. Behcet's syndrome: a report of 41 patients with emphasis on neurological manifestations. J Neurol Neurosurg Psychiatry 1998;64:382-384. Wermes C, Fleischhack G, Junker R, et al. Cerebral venous sinus thrombosis in children with acute lymphoblastic leukemia carrying the MTHFR TT677 genotype and further prothrombotic risk factors. Klin Padiatr 1999;211:211-214. Hillmen P, Lewis SM, Bessler M, Luzzatto L, Dacie JV. Natural history of paroxysmal nocturnal hemoglobinuria. N Engl J Med 1995;333:1253-1258. de Bruijn SF, Stam J, Koopman MM, Vandenbroucke JP. Case-control study of risk of cerebral sinus thrombosis in oral contraceptive users and in carriers of hereditary prothrombotic conditions. BMJ 1998;316:589-592. Stiefel D, Eich G, Sacher P. Posttraumatic dural sinus thrombosis in children. Eur J Pediatr Surg 2000;10:41-44. Wilder-Smith E, Kothbauer-Margreiter I, Lammle B, Sturzenegger M, Ozdoba C, Hauser SP. Dural puncture and activated protein C resistance: risk factors for cerebral venous sinus thrombosis. J Neurol Neurosurg Psychiatry 1997;63:351-356. de Bruijn SF, Stam J, Vandenbroucke JP. Increased risk of cerebral venous sinus thrombosis with third-generation oral contraceptives. Lancet 1998;351:1404-1404. Krayenbühl HA. Cerebral venous and sinus thrombosis. Clin Neurosurg 1966;14:1-24. de Bruijn SFTM, ed. Cerebral venous sinus thrombosis: clinical and epidemiological studies. Amsterdam: Thesis, 1998. Vandenbroucke JP, Rosing J, Bloemenkamp KW, et al. Oral contraceptives and the risk of venous thrombosis. N Engl J Med 2001;344:1527-1535. Aidi S, Chaunu MP, Biousse V, Bousser MG. Changing pattern of headache pointing to cerebral venous thrombosis after lumbar puncture and intravenous high-dose corticosteroids. Headache 1999;39:559-564. de Bruijn SF, Stam J, Kappelle LJ. Thunderclap headache as first symptom of cerebral venous sinus thrombosis. Lancet 1996;348:1623-1625. Kothare SV, Ebb DH, Rosenberger PB, Buonanno F, Schaefer PW, Krishnamoorthy KS. Acute confusion and mutism as a presentation of thalamic strokes secondary to deep cerebral venous thrombosis. J Child Neurol 1998;13:300-303. Lafitte F, Boukobza M, Guichard JP, et al. MRI and MRA for diagnosis and follow-up of cerebral venous thrombosis (CVT). Clin Radiol 1997;52:672-679. Dormont D, Anxionnat R, Evrard S, Louaille C, Chiras J, Marsault C. MRI in cerebral venous thrombosis. J Neuroradiol 1994;21:81-99. Isensee C, Reul J, Thron A. Magnetic resonance imaging of thrombosed dural sinuses. Stroke 1994;25:29-34. Ayanzen RH, Bird CR, Keller PJ, McCully FJ, Theobald MR, Heiserman JE. Cerebral MR venography: normal anatomy and potential diagnostic pitfalls. AJNR Am J Neuroradiol 2000;21:74-78. de Bruijn SF, de Haan RJ, Stam J. Clinical features and prognostic factors of cerebral venous sinus thrombosis in a prospective series of 59 patients. J Neurol Neurosurg Psychiatry 2001;70:105-108. Stefini R, Latronico N, Cornali C, Rasulo F, Bollati A. Emergent decompressive craniectomy in patients with fixed dilated pupils due to cerebral venous and dural sinus thrombosis: report of three cases. Neurosurgery 1999;45:626-629. Diaz JM, Schiffman JS, Urban ES, Maccario M. Superior sagittal sinus thrombosis and pulmonary embolism: a syndrome rediscovered. Acta Neurol Scand 1992;86:390-396. Einhaupl KM, Villringer A, Meister W, et al. Heparin treatment in sinus venous thrombosis. Lancet 1991;338:597-600. de Bruijn SF, Stam J. Randomized, placebo-controlled trial of anticoagulant treatment with low-molecular-weight heparin for cerebral sinus thrombosis. Stroke 1999;30:484-488. Nagaraja D, Rao BSS, Taly AB, Subhash MN. Randomized controlled trial of heparin in puerperal cerebral venous/sinus thrombosis. Nimhans J 1995;13:111-5. Stam J, De Bruijn SF, DeVeber G. Anticoagulation for cerebral sinus thrombosis. Cochrane Database Syst Rev 2002;4:CD002005-CD002005. Bousser MG. Cerebral venous thrombosis: nothing, heparin, or local thrombolysis? 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☉ 11325820:A Gain-of-Function Mutation of JAK2 in Myeloproliferative Disorders
ABSTRACT Background Polycythemia vera, essential thrombocythemia, and idiopathic myelofibrosis are clonal myeloproliferative disorders arising from a multipotent progenitor. The loss of heterozygosity (LOH) on the short arm of chromosome 9 (9pLOH) in myeloproliferative disorders suggests that 9p harbors a mutation that contributes to the cause of clonal expansion of hematopoietic cells in these diseases. Methods We performed microsatellite mapping of the 9pLOH region and DNA sequencing in 244 patients with myeloproliferative disorders (128 with polycythemia vera, 93 with essential thrombocythemia, and 23 with idiopathic myelofibrosis). Results Microsatellite mapping identified a 9pLOH region that included the Janus kinase 2 (JAK2) gene. In patients with 9pLOH, JAK2 had a homozygous GT transversion, causing phenylalanine to be substituted for valine at position 617 of JAK2 (V617F). All 51 patients with 9pLOH had the V617F mutation. Of 193 patients without 9pLOH, 66 were heterozygous for V617F and 127 did not have the mutation. The frequency of V617F was 65 percent among patients with polycythemia vera (83 of 128), 57 percent among patients with idiopathic myelofibrosis (13 of 23), and 23 percent among patients with essential thrombocythemia (21 of 93). V617F is a somatic mutation present in hematopoietic cells. Mitotic recombination probably causes both 9pLOH and the transition from heterozygosity to homozygosity for V617F. Genetic evidence and in vitro functional studies indicate that V617F gives hematopoietic precursors proliferative and survival advantages. Patients with the V617F mutation had a significantly longer duration of disease and a higher rate of complications (fibrosis, hemorrhage, and thrombosis) and treatment with cytoreductive therapy than patients with wild-type JAK2. Conclusions A high proportion of patients with myeloproliferative disorders carry a dominant gain-of-function mutation of JAK2. The myeloproliferative disorders are a heterogeneous group of diseases characterized by excessive production of blood cells by hematopoietic precursors. In addition to thrombotic and hemorrhagic complications, leukemic transformation can occur.1 Typically, the myeloproliferative disorders encompass four related entities2: chronic myelogenous leukemia (CML), polycythemia vera, essential thrombocythemia, and idiopathic myelofibrosis. Clonal hematopoiesis is a key feature of these disorders.3,4,5 The lesion is believed to involve the hematopoietic stem cell, since all myeloid lineages and, frequently, the B-cell lineage are monoclonal. T cells, however, are polyclonal.4,6 Progenitor cells in polycythemia vera form erythroid colonies in the absence of exogenous erythropoietin. These endogenous erythroid colonies7 have been used in an auxiliary diagnostic assay to distinguish polycythemia vera from secondary erythrocytosis,8 but they also occur in some cases of essential thrombocythemia and idiopathic myelofibrosis. More important, the presence of endogenous erythroid colonies is a hallmark of abnormal in vitro growth of hematopoietic progenitors, and this finding has been the basis of many studies of signaling by cytokine receptors of hematopoietic cells. These receptors transduce signals by activating members of the Janus kinase (JAK) family of proteins, which phosphorylate cytoplasmic targets, including the signal transducers and activators of transcription (STATs).9 Constitutive activation of the STAT3 protein has been found in 30 percent of patients with polycythemia vera,10 and a decrease in the level of the thrombopoietin receptor protein in platelets is a feature of both polycythemia vera and essential thrombocythemia.11,12 Only the late steps of differentiation of endogenous erythroid colonies in polycythemia vera are erythropoietin-independent, and they can be blocked by inhibitors of JAK2, phosphatidylinositol 3' kinase, or kinases of the Src family.13 Recently, the tyrosine kinase inhibitor imatinib mesylate has been reported to produce clinical responses in patients with polycythemia vera.14,15 These data suggest the involvement of a kinase in the pathogenesis of myeloproliferative disorders. Cytogenetic abnormalities occur in only 10 to 15 percent of patients with myeloproliferative disorders.16,17,18 The most common abnormalities are deletions in chromosome 20q.19,20 Fluorescence in situ hybridization and comparative genomic hybridization suggested a role for chromosome 9p.20,21,22,23 Using genome-wide microsatellite screening, we identified loss of heterozygosity (LOH) on the short arm of chromosome 9 (9pLOH) in six patients with polycythemia vera24; using microsatellite markers within the LOH region, we found 9pLOH in 13 of 43 patients with polycythemia vera and 1 of 15 patients with essential thrombocythemia.24,25 Markers from the 9pLOH region did not cosegregate with the phenotype in four families with polycythemia vera, suggesting that a somatic event causes 9pLOH.26 In the present study, we increased the number of microsatellite markers in order to map a minimal genomic region shared by all patients with 9pLOH and myeloproliferative disorders to identify potential candidate genes. Methods Subjects We evaluated 244 patients with myeloproliferative disorders from Switzerland and Italy: 128 patients with polycythemia vera, 93 with essential thrombocythemia, and 23 with idiopathic myelofibrosis.25,27,28 We studied 41 healthy persons, 9 patients with chronic myelogenous leukemia, and 11 patients with secondary erythrocytosis as controls. The study was approved by the local ethics committees, and all samples were obtained after subjects provided written informed consent. In addition, we used DNA from 30 archival samples. The diagnostic criteria of the World Health Organization (WHO) were followed for all Swiss patients, whereas the Polycythemia Vera Study Group (PVSG) criteria were used for all Italian patients.29,30,31 The main difference between the two classifications is the use of bone marrow histologic findings as a diagnostic criterion in the WHO classification to distinguish early stages of idiopathic myelofibrosis from essential thrombocythemia or polycythemia vera. The presence of endogenous erythroid colonies is a major WHO criterion and a minor PVSG criterion. Isolation of Cells and DNA Granulocytes were isolated,24 and analysis of cytospin preparations verified that the purity exceeded 90 percent. Peripheral-blood CD4+ T cells were isolated by means of magnetic sorting (Miltenyi Biotech). Peripheral-blood mononuclear cells (PBMCs) were prepared with the use of Ficoll gradient centrifugation. Buccal mucosal cells were obtained with cytologic brushes, and hair-follicle DNA was prepared from plucked hair. Genomic DNA was isolated with the use of the QIAmp DNA Blood Mini Kit (Qiagen). Detection of LOH LOH was detected by means of fluorescence microsatellite polymerase-chain-reaction (PCR) analysis with the use of primer sequences from public databases (listed in the Supplementary Appendix, available with the complete text of this article at www.nejm.org). The samples were analyzed on a DNA genetic analyzer (model 3100, Applied Biosystems). LOH was considered to be present if one allele showed a reduction in the peak fluorescence intensity of more than 90 percent in granulocytes, but two alleles were present in nonclonal tissues (T cells, PBMCs, buccal mucosa, or hair-follicle cells) from the same patient. Analysis of the Number of Gene Copies The number of copies of chromosome 9p in granulocyte DNA was determined with the use of quantitative PCR by comparing two single-copy loci: one in exon 14 of JAK2 and an uncharacterized gene on chromosome 13. The primers and details of these assays are provided in the Supplementary Appendix. JAK2 Sequencing We sequenced the JAK2 complementary DNA (cDNA) with reverse-transcriptase (RT) PCR using seven pairs of overlapping primers described in the Supplementary Appendix (sequence information is available on request). DNA Constructs The mutant JAK2 cDNA was amplified by RT-PCR with the use of granulocyte RNA from a patient who was homozygous for the mutation. The Supplementary Appendix gives details of the primers and cloning into vectors. Proliferation Assays The mouse interleukin 3–dependent cell line BaF3 and the human thrombopoietin-dependent cell line UT-7/TPO (kindly provided by Dr. N. Komatsu) were transfected by electroporation with the wild-type JAK2 (plasmid murine stem-cell virus –Jak2) and mutant JAK2 (pMSCV-V617F-Jak2) constructs. The Supplementary Appendix gives details of the assays for proliferation and cell viability. Immunoprecipitation and Western Blotting BaF3 cells were incubated in a culture medium (RPMI) containing 10 percent fetal-calf serum in the absence of interleukin-3 for 12 hours at 37°C, whereupon various concentrations of interleukin-3 were added for 15 minutes. Cell lysates were prepared as previously described.32 Immunoprecipitation and immunoblotting were carried out with the use of polyclonal antibodies against JAK2 (Upstate) and STAT5 (Santa Cruz) and the phosphotyrosine-specific mouse monoclonal antibody 4G10 (Upstate). Statistical Analysis We used the chi-square or Fisher's exact test where appropriate to compare categorical variables among the groups, which were categorized according to mutational status (heterozygous, homozygous, or wild type), and the Mann–Whitney U test or Kruskal–Wallis test to compare continuous variables among the groups. For some analyses, the heterozygous and the homozygous groups of patients were pooled and compared with patients without JAK2 mutations. Results Fine Mapping of the Common 9pLOH Region Using 10 microsatellite markers covering chromosome 9p, we found 9pLOH in granulocytes from 51 of 244 patients with myeloproliferative disorders (21 percent), but not in those from any of the control subjects: 41 healthy subjects, 9 patients with CML, and 11 patients with secondary erythrocytosis. The frequency of 9pLOH was 34 percent among patients with polycythemia vera, 22 percent among patients with idiopathic myelofibrosis, and 3 percent among patients with essential thrombocythemia. The size of the chromosomal region showing LOH varied, but the telomeric region of chromosome 9p was always involved (Figure 1A). By aligning the LOH regions of all 51 patients with 9pLOH, we identified a 6.2-Mbp interval common to all patients that extended from the telomere to marker D9S1852 and contained the gene for the tyrosine kinase JAK2 (Figure 1B). Since JAK2 mediates signaling through several hematopoietic cytokine receptors, we considered JAK2 an attractive candidate gene. Figure 1. Mapping of the Minimal 9pLOH Region in Patients with Myeloproliferative Disorders. Panel A shows the mapping results for 51 patients with 9pLOH. Solid squares indicate LOH in granulocytes detected by the corresponding microsatellite marker; open squares represent the absence of LOH. Vertical lines represent individual patients. The patients' results are arranged from left to right in the order of increasing size of the LOH region. The minimal LOH region is delineated by the gray background color. For clarity, markers that were uninformative have been omitted. Panel B shows a physical map of genes within the common 9pLOH region (not drawn to scale). The positions of microsatellite markers used to identify the common LOH region (gray zone) are shown as vertical lines. Numbers indicate the physical distance from the chromosome 9p telomere in megabase pairs (Mbp). Black boxes represent genes. The results of microsatellite mapping in four patients with the shortest LOH region are shown below the map. Solid squares indicate LOH, and open squares represent the absence of LOH. The mitotic recombination breakpoint in these patients occurred in the 0.9-Mbp region between the markers D9S1681 and D9S1852. 9pLOH and a GT Mutation in the Coding Region of JAK2 The coding region of JAK2 in all 51 patients with 9pLOH had a GT transversion that changed a valine to a phenylalanine at position 617 (V617F; GenBank accession number AY973037 ) (Table 1 and Figure 2). All patients with 9pLOH are expected to be homozygous (both alleles mutated) or hemizygous (one allele mutated and the other absent) for the V617F mutation. However, in eight patients, the findings were compatible with the presence of heterozygosity (one allele was mutated, and the other was wild type) (Table 1). Our definition of LOH allows 10 percent of granulocytes without 9pLOH to be present in a given sample and the ratios of G and T peak intensities in sequencing chromatograms cannot be used to quantify allelic ratios. It is therefore likely that an admixture of granulocytes with wild-type or heterozygous V617F genotypes caused the apparent heterozygosity in these eight patients. Of the remaining 193 patients without 9pLOH, 34 percent were heterozygous for V617F and 66 percent were homozygous for the wild-type allele; none were homozygous for V617F (Table 1). The V617F mutation was absent in 71 healthy controls, 11 patients with secondary erythrocytosis, and 9 patients with CML (Table 1). Table 1. Frequency of the JAK2 V617F Mutation. Figure 2. The JAK2 Mutation in Patients with Myeloproliferative Disorders. Panel A shows a homozygous GT transversion in JAK2 (arrow) in a patient with 9pLOH (left) and a heterozygous mutation in a patient without 9pLOH (right). The mutation was present in DNA from granulocytes, but absent in T cells, consistent with the existence of an acquired somatic origin of the mutation. Panel B shows the domain structure of the JAK2 protein. Numbers indicate the amino acid position within the protein. The arrow indicates the position of the V617F mutation. The alignment of sequences of the JAK family of proteins is shown below. Panel C shows the somatic origin of the JAK2 mutation. DNA from granulocytes and buccal mucosa cells showed the GT transversion, but DNA from hair follicles demonstrated absence of the mutation. FERM denotes band 4.1(f), ezrin, radixin, and moesin; and SH2 SRC homology 2. The mutation was present in 65 percent of patients with polycythemia vera, as compared with 57 percent of those with idiopathic myelofibrosis (P=0.72) and 23 percent of those with essential thrombocythemia (P<0.001) (Table 1). Homozygosity for V617F was underrepresented among patients with essential thrombocythemia, as compared with patients with polycythemia vera and patients with idiopathic myelofibrosis, and was linked to the presence of 9pLOH. The median duration of disease was significantly longer among patients with myeloproliferative disorders who were homozygous for the V617F mutation than among those who were heterozygous for the mutation (48 months vs. 23 months , P<0.02 by the Mann–Whitney U test). This difference is compatible with the existence of a two-step process to acquire homozygosity. Interestingly, patients with myeloproliferative disorders who had wild-type JAK2 had the shortest duration of disease (15 months; range, 0 to 330; P=0.05 for the comparison with heterozygous patients). Identification of a Somatic Mutation in Myeloproliferative Disorders We sequenced DNA from T cells, PBMCs, or nonhematopoietic tissues from 89 patients with the V617F mutation. We could not detect the mutant JAK2 allele in these control tissues, a result consistent with the existence of a somatic mutation. In two patients, we detected the V617F mutation in buccal mucosa cells, but since samples of buccal mucosa can be contaminated with blood, we analyzed hair-follicle cells from these patients and found only the wild-type JAK2 sequence (Figure 2C). Cause of 9pLOH The 9pLOH in myeloproliferative disorders could result from deletions of the telomeric portions of chromosome 9p or mitotic recombination between chromatids of homologous 9p chromosomes (Figure 3A). In the case of a deletion, we would expect to find only one copy of DNA for the deleted region, whereas two copies should be expected in the event of mitotic recombination (Figure 3A). To evaluate these possibilities, we used quantitative PCR to determine the number of copies of JAK2 and, as a control, the number of copies of a single-copy gene on chromosome 13. Of 33 patients with 9pLOH, all had two copies of chromosome 9p (Figure 3B). This result argues against deletions as the cause of 9pLOH and makes mitotic recombination the most likely mechanism. We also analyzed parental chromosomes of two patients with 9pLOH. In one (Patient 50), the maternally derived chromosome 9p was lost, whereas in the other (Patient 116), the paternal chromosome 9p was missing (Figure 3C). Thus, either maternal or paternal chromosome 9p can be lost, suggesting that genomic imprinting is not involved in the expansion of cells with 9pLOH. Figure 3. Mechanisms of 9pLOH. Two alternative models are presented in Panel A. The chromosome 9 with the wild-type JAK2 sequence (G) is depicted in white, and the chromosome 9 with the GT transversion (T) is shown in red. Circles symbolize the nuclei of the cells. Deletion of the telomeric part of wild-type chromosome 9p as a potential mechanism for 9pLOH is shown on the left. Alternatively, mitotic recombination could also result in 9pLOH, shown on the right. The events during mitosis and the resulting cell progeny after mitotic recombination of chromosome 9p are also shown. Panel B shows the number of copies of JAK2 among 33 patients with 9pLOH, 12 healthy controls, and 3 archival tumor samples from patients with monosomy 9. Panel C shows the parental origin of the lost chromosome in two patients with 9pLOH. In one (Patient 50), the maternally derived chromosome 9p was lost, whereas in the other (Patient 116), the paternal chromosome 9p was missing. Data obtained by real-time polymerase chain reaction comparing the abundance of JAK2 and a single copy gene on chromosome 13 are shown (CT). Proliferative and Survival Advantage Afforded by V617F To investigate whether the V617F mutation has functional consequences, we analyzed data on endogenous erythroid colonies in 180 patients with myeloproliferative disorders. Endogenous erythroid colonies were present in 77 of 87 patients with the V617F mutation, whereas only 57 of 93 patients without the mutation had them (P<0.001 by Fisher's exact test). Next, we expressed the JAK2 V617F protein in the mouse interleukin-3–dependent cell line BaF3 (Figure 4). These transfected cells were hypersensitive to low concentrations of interleukin-3 and were more numerous (elevated baseline value) than control cells in the absence of interleukin-3 (Figure 4A). The same results were obtained in four independent experiments and in analogous experiments with BaF3 cells that were doubly transfected with the erythropoietin receptor gene and JAK2 and in V617F-transfected thrombopoietin-dependent UT-7/TPO human cells (data not shown). Figure 4. Functional Effects of the JAK2 V617F Mutation in Stably Transfected Murine Interleukin-3–Dependent BaF3 Cells. Panel A shows the proliferation of BaF3 cells transfected with the V617F mutant JAK2, the wild-type JAK2, or the empty vector in the absence of interleukin-3 (a concentration of 0) and the presence of increasing concentrations of interleukin-3, as determined by the tetrazolium salt (XTT) assay. The mean (±SD) of triplicate results is shown (in some cases, the error bars are hidden behind the symbols). Increased optical density (OD) of the XTT dye corresponds to increased numbers of cells. Panel B shows the survival of stably transfected BaF3 cells in the absence of interleukin-3. The percentage of viable cells was determined by the exclusion of the dye trypan blue from the cells. The mean (±SD) of triplicate results is shown. Panel C shows stably transfected BaF3 cells maintained in the absence of interleukin-3 for 10 days. BaF3 cells transfected with JAK2 V617F are viable, whereas almost all cells transfected with the wild-type JAK2 or the empty vector are dead. Panel D shows the activation of JAK2 and STAT5 in response to interleukin-3. BaF3 cells transfected with the empty vector (V), the wild-type JAK2 (W), or the JAK2 V617F mutant (M) were incubated for 12 hours without interleukin-3 but with 10 percent fetal-calf serum and were then stimulated for 15 minutes with increasing concentrations of interleukin-3, as indicated. Immunoprecipitation (IP) was carried out with the phosphotyrosine-specific mouse monoclonal antibody 4G10 (pTyr) followed by Western blotting (WB) with the use of antibodies against JAK2 or STAT5, as indicated. Levels of expression of JAK2 and STAT5 proteins in the lysates used for immunoprecipitation were visualized by immunoblotting with the use of the corresponding antibodies and are shown at the bottom. Interleukin-3, erythropoietin, and thrombopoietin signaling is dependent on JAK2.33,34 Differences in cell viability were apparent when the transfected BaF3 cell lines were maintained in serum-containing medium in the absence of interleukin-3 (Figure 4B). This result suggests that the transfected JAK2 mutant increased survival of the cells in the absence of the cytokine. Since the proliferation assay measures the numbers of cells after three days of culture, the results obtained in the absence of interleukin-3 in Figure 4A can be compared with those of the viability curves on day 3 in Figure 4B: both show approximately twice the number of viable mutant cells as control cells. When kept under the same conditions for more than 10 days, BaF3 cells transfected with the JAK2 V617F survived, and their numbers increased by a factor of 100, whereas cells transfected with the wild-type JAK2 or the vector control died (Figure 4C). We also examined the phosphorylation of JAK2 and STAT5 proteins under the same conditions as in the proliferation assays (Figure 4D). JAK2 phosphorylation was only slightly increased in the absence of or at low concentrations of interleukin-3. A more pronounced difference was detected in the phosphorylation of STAT5, one of the principal protein substrates of JAK2 (Figure 4D). At higher interleukin-3 concentrations, these differences disappeared. The differences in signaling mirrored the differences in growth and survival observed at the same cytokine concentrations. Thus, the presence of JAK2 V617F conferred a proliferative and survival advantage by rendering the cells more sensitive to incoming stimulatory signals. Correlations with Clinical Data Possible associations between the V617F mutation and clinical features were retrospectively analyzed in 244 patients. The only significant differences between patients who were heterozygous and those who were homozygous for the V617F mutation were the above-mentioned increase in the median duration of disease and the correlation between 9pLOH and homozygosity for the mutation. Therefore, we limited our comparison to patients with the V617F mutation and those without the mutation (Table 2). Significantly more patients with the mutation than without the mutation had complications (secondary fibrosis, hemorrhage, and thrombosis) and had received cytoreductive treatment. Of five patients with leukemic transformation, four had the V617F mutation (P=0.20). Table 2. Characteristics Associated with the JAK2 V617F Mutation. Discussion Fine mapping of the 9pLOH region in patients with myeloproliferative disorders identified a 6.2-Mbp genomic interval that contains the gene for the tyrosine kinase JAK2 (Figure 1). This gene, JAK2, was a strong candidate for causing clonal expansion of hematopoietic progenitors in myeloproliferative disorders because of its essential function in hematopoiesis.33,34 We found a GT transversion that results in a change in a single amino acid, V617F, in the pseudokinase domain of JAK2 (Figure 2 and Table 1). V617F is not a polymorphism, since it was absent from 142 chromosomes of healthy people and is not recorded in the databases of single-nucleotide polymorphisms. Moreover, we did not detect the V617F mutation in 11 patients with secondary erythrocytosis or 9 patients with CML. We found conclusive evidence that V617F is a somatic mutation in hematopoietic cells. We cannot exclude the possibility of germ-line mutations in some cases of familial myeloproliferative disorders, although chromosome 9p was previously excluded by linkage analysis in four families with polycythemia vera.26 The frequency of the V617F mutation was highest among patients with polycythemia vera and lowest among patients with essential thrombocythemia (Table 1). Essential thrombocythemia is the most heterogeneous myeloproliferative disorder, with a substantial proportion of patients showing polyclonal hematopoiesis.4,6,35 The low frequency of 9pLOH in this disease might reflect the low mitotic activity in the essential-thrombocythemia progenitor or stem-cell pool. It is remarkable that we found an identical somatic GT transversion in JAK2 in 117 unrelated patients, or 48 percent of the patients with myeloproliferative disorders (Table 1). The V617F mutation is located in the pseudokinase domain of JAK2 (Figure 2B), a region that inhibits JAK2 kinase activity.36,37 Mutations affecting this domain are associated with malignant transformation of hematopoietic cells in drosophila.38 BaF3 and UT-7/TPO cells that were transfected with the mutant JAK2 gene were hypersensitive to low concentrations of interleukin-3 and erythropoietin and thrombopoietin, respectively. In the presence of serum, transfected BaF3 cells showed increased survival, proliferation, and phosphorylation of JAK2 and STAT5, even in the absence of interleukin-3 (Figure 4). This result suggests that other cytokines in serum at low concentrations are most likely sufficient to maintain the viability and proliferation of cells expressing JAK2 V617F. Similarly, the growth of endogenous erythroid colonies in myeloproliferative disorders also depends on the presence of serum.39 The effect of the JAK2 V617F mutation on the proliferation of BaF3 cells was less dramatic than that of the TEL-JAK2 fusion protein found in acute lymphoblastic leukemias.40 The relatively subtle effect of the V617F mutation fits well with the mild and indolent nature of the clonal proliferation observed in myeloproliferative disorders. Hypersensitivity to insulin-like growth factor, thrombopoietin, interleukin-3, and other cytokines has been described in hematopoietic progenitor cells from patients with myeloproliferative disorders.39,41,42,43 How the V617F mutation sustains the increased phosphorylation of JAK2 in the presence of serum, but in the absence of interleukin-3, and the factor or factors in serum that mediate this effect remain unknown. Nevertheless, the functional relevance of the V617F mutation is supported by the finding that endogenous erythroid colonies were present in 89 percent of patients with V617F and the close association between homozygosity for the V617F mutation and 9pLOH, which demonstrates the survival advantage of such homozygous hematopoietic cells. The gene-dosage analysis suggests that mitotic recombination between chromatids of homologous chromosomes 9p is the most likely mechanism leading to 9pLOH (Figure 3). The absence of homozygosity for the V617F mutation in patients with myeloproliferative disorders who do not have 9pLOH suggests that a transition from heterozygosity to homozygosity by means of a mechanism that is independent of mitotic recombination is rare. Mitotic recombination is a frequent genetic mechanism in the inactivation of tumor-suppressor genes in solid tumors,44,45,46 but not in malignant diseases of the hematopoietic system.47 Our data suggest two possible pathogenetic mechanisms of the JAK2 V617F mutation. In one (model A in Figure 5), the heterozygous JAK2 V617F mutation alone or in combination with one or more preexisting somatic mutations causes the myeloproliferative-disorder phenotype in approximately 50 percent of patients. A somatic mutation in an as yet unknown gene would be responsible for the phenotype in the other patients (not shown). This model does not explain the presence of the V617F mutation in several myeloproliferative disorders. Perhaps the genetic background or additional somatic mutations in hematopoietic cells alter the effects of the V617F mutation on the phenotype. In model B, JAK2 V617F occurs after the appearance of the myeloproliferative-disorder phenotype as a mutation associated with disease progression but is not necessary or sufficient to cause the phenotype (Figure 5). In this model, patients with myeloproliferative disorders without the JAK2 mutation have an early stage of the disease. One prediction of this model is that the duration of disease should be shortest in patients without the JAK2 mutation and longest in those who are homozygous for the V617F mutation, as we observed. In both models, the transition from heterozygosity to homozygosity for the mutation represents clonal evolution. Our data indicate that mitotic recombination in patients with 9pLOH produces a daughter cell that is homozygous for the V617F mutation and can outcompete the parental cells that are heterozygous (Figure 3A and Figure 5). Figure 5. Possible Roles of the JAK2 V617F Mutation in Myeloproliferative Diseases. In model A, a mutation (V617F) of one allele of JAK2 on chromosome 9p (red dot), alone or in combination with a hypothetical preexisting mutation in an unknown gene ("X"), initiates the onset of the myeloproliferative disease (dashed arrow). In model B, the heterozygous V617F mutation on 9p occurs after the initiation of the myeloproliferative disease (dashed arrow), which was provoked by one or more mutations in an unknown gene or genes. Cells that are heterozygous for the V617F mutation have a proliferative advantage over cells bearing only the wild-type allele. Mitotic recombination between homologous regions of the two chromosomes 9 in a cell heterozygous for V617F results in loss of heterozygosity of 9p (9pLOH). One of the daughter cells is homozygous for V617F and gains an additional proliferative advantage. This cell establishes a subclone that outcompetes both cells that are heterozygous for V617F and cells that are homozygous for wild-type JAK2. Evaluation of the clinical data (Table 2) revealed significant correlations between the presence of the V617F mutation and the frequency of complications (secondary fibrosis, hemorrhage, and thrombosis). These correlations could be a consequence of the longer duration of disease in patients with the JAK2 mutation or could be linked to a more aggressive phenotype, perhaps owing to an increased responsiveness to cytokines. Patients with the V617F mutation were older than those without the mutation, and a higher proportion had received cytoreductive therapy at the time of sample collection. The increased frequency of cytoreductive therapy does not necessarily imply the presence of a more aggressive disease and could be based on age alone, according to widely accepted therapeutic guidelines. Taken together, our data suggest that the V617F mutation in JAK2 is a dominant gain-of-function mutation that contributes to the expansion of the myeloproliferative-disorder clone. The V617F mutation could form the basis for a new molecular classification of myeloproliferative disorders. Furthermore, in view of the invariant nature of the JAK2 mutation, small molecules could be developed that specifically target the mutated protein in patients with myeloproliferative disorders. Supported in part by a grant (3100-066 949.01) from the Swiss National Science Foundation, grants (OCS-01163-09-2001 and OCS-01411-08-2003) from the Swiss Cancer League, and a grant from the Stiftung für H?matologische Forschung (all to Dr. Skoda); by a grant from the Krebsliga beider Basel (to Dr. Kralovics); and by a grant from the Associazione Italiana per la Ricerca sul Cancro, Milan (to Dr. Cazzola). We are indebted to the patients and their physicians for contributing to the study, to Gary Gilliland for sharing data before publication, to Guido Sauter for providing cells with monosomy 9, and to Alois Gratwohl, Jürg Schwaller, Markus Heim, and Ed Palmer for helpful comments on the manuscript. Source Information From the Department of Research, Experimental Hematology (R.K., S.-S.T., R.T., R.C.S.), and the Departments of Hematology (A.S.B., J.R.P.) and Laboratory Medicine (A.T.), University Hospital Basel, Basel, Switzerland; and the Division of Hematology, University of Pavia Medical School and Istituto di Ricovero e Cura a Carattere Scientifico, Policlinico San Matteo, Pavia, Italy (F.P., M.C.). Address reprint requests to Dr. Skoda at the Department of Research, University Hospital Basel, Hebelstr. 20, CH-4031 Basel, Switzerland, or at radek.skoda@unibas.ch. References Spivak JL. Polycythemia vera: myths, mechanisms, and management. Blood 2002;100:4272-4290. Dameshek W. 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☉ 11325821:Multidetector-Row Computed Tomography in Suspected Pulmonary Embolism
ABSTRACT Background Single-detector–row computed tomography (CT) has a low sensitivity for pulmonary embolism and must be combined with venous-compression ultrasonography of the lower limbs. We evaluated whether the use of D-dimer measurement and multidetector-row CT, without lower-limb ultrasonography, might safely rule out pulmonary embolism. Methods We included 756 consecutive patients with clinically suspected pulmonary embolism from the emergency departments of three teaching hospitals and managed their cases according to a standardized sequential diagnostic strategy. All patients were followed for three months. Results Pulmonary embolism was detected in 194 of the 756 patients (26 percent). Among the 82 patients with a high clinical probability of pulmonary embolism, multidetector-row CT showed pulmonary embolism in 78, and 1 patient had proximal deep venous thrombosis and a CT scan that was negative for pulmonary embolism. Of the 674 patients without a high probability of pulmonary embolism, 232 (34 percent) had a negative D-dimer assay and an uneventful follow-up; CT showed pulmonary embolism in 109 patients. CT and ultrasonography were negative in 318 patients, of whom 3 had a definite thromboembolic event and 2 died of possible pulmonary embolism during follow-up (three-month risk of thromboembolism, 1.7 percent; 95 percent confidence interval, 0.7 to 3.9). Two patients had proximal deep venous thrombosis and a negative CT scan (risk, 0.6 percent; 95 percent confidence interval, 0.2 to 2.2). The overall three-month risk of thromboembolism in patients without pulmonary embolism would have been 1.5 percent (95 percent confidence interval, 0.8 to 3.0) if the D-dimer assay and multidetector-row CT had been the only tests used to rule out pulmonary embolism and ultrasonography had not been performed. Conclusions Our data indicate the potential clinical use of a diagnostic strategy for ruling out pulmonary embolism on the basis of D-dimer testing and multidetector-row CT without lower-limb ultrasonography. A larger outcome study is needed before this approach can be adopted. Computed tomography (CT) is increasingly being used as the main thoracic imaging technique in suspected pulmonary embolism.1,2,3,4 First-generation single-detector–row helical CT scanners have a 90 percent specificity but only a 70 percent sensitivity for pulmonary embolism.5,6,7,8 In series in which venous-compression ultrasonography of the lower limbs and single-detector–row helical CT were performed in all patients with clinically suspected pulmonary embolism,7,9 the proportion of patients with deep venous thrombosis despite findings on CT that were negative for pulmonary embolism was 6 to 9 percent. The implication of this finding is that lower-limb ultrasonography must be combined with CT to improve the overall diagnostic yield. In two recent outcome studies,9,10 patients without a high clinical probability of pulmonary embolism who were left untreated on the basis of negative findings on single-detector CT and lower-limb compression ultrasonography had a 1 to 2 percent risk of a thromboembolic event within three months, a finding that is similar to that for patients who were left untreated after pulmonary angiography showed no abnormalities.11 The advent of multidetector-row CT scanners has improved the visualization of the segmental and subsegmental pulmonary arteries.12,13 This development has raised the possibility that pulmonary embolism might be safely ruled out without the use of lower-limb venous ultrasonography, at least in patients without a high probability of pulmonary embolism — a change in strategy that could save both money and other resources. If that hypothesis were true, the diagnosis of deep venous thrombosis in a patient with clinically suspected pulmonary embolism and negative findings on multidetector-row CT should be uncommon, and the three-month risk of thromboembolism in patients with a negative multidetector-row CT scan should be low. Therefore, we conducted a prospective study to assess whether a strategy of D-dimer measurement and multidetector-row CT, without the use of lower-limb ultrasonography, might safely rule out pulmonary embolism in patients admitted to the emergency department for clinically suspected pulmonary embolism. Methods Patients Consecutive patients who presented to the emergency department were eligible if there was a suspicion of pulmonary embolism, which was defined as acute onset of new or worsening shortness of breath or chest pain without another obvious cause. Among the 1014 screened patients, 185 (18 percent) were excluded from the study for the following reasons: a contraindication to CT (i.e., a known allergy to iodine contrast agents or a risk of allergic reaction) (7 patients); impaired renal function, defined as a creatinine clearance below 30 ml per minute, as calculated by the Cockcroft–Gault formula14 (38); pregnancy (7); ongoing anticoagulant therapy for a reason other than venous thromboembolism (38); a decision not to participate in the study (41); inability to give informed consent (15); a life expectancy of less than three months (9); a diagnosis that had been made before admission (3); unavailability for follow-up (10); hospitalization in another institution for more than 24 hours before admission (3); inability to undergo CT because of hemodynamic instability (3); transfer to another facility (1); absence of peripheral venous access (1); and other reasons (9). Another 73 patients (7.2 percent) were excluded because of the following violations in study protocol: clinical probability was not assessed (14 patients); diagnostic tests were not performed, including D-dimer measurement (4), ultrasonography (15), CT (8), and angiography (7); tests were inadequately performed despite a negative D-dimer test (2); a decision was made by the physicians in charge to prescribe anticoagulants, despite the absence of pulmonary embolism according to the study criteria (5); or the diagnosis was not confirmed according to study criteria in patients whose CT scan was inconclusive for technical reasons (17) or because of the presence of isolated subsegmental pulmonary embolism (1). Hence, the final study cohort consisted of 756 patients (75 percent of the screened population). Study Design The study was designed as a prospective management trial with a three-month follow-up. Data were collected from August 1, 2002, to November 30, 2003, at three participating medical centers that serve as general and teaching hospitals (Geneva University Hospital, Geneva; Angers University Hospital, Angers, France; and H?pital Européen Georges-Pompidou, Paris). The study was approved by the ethics committees of Geneva University Hospital and Angers University Hospital, and all patients provided written informed consent before they were enrolled. Drs. Perrier, Bounameaux, Roy, and Meyer designed the study. A research assistant gathered the data in each center, and the local study coordinator checked the data. Drs. Perrier and Le Gal performed the analysis and vouch for the data and the analysis. All the authors participated in the interpretation of the data and approved the final version of the article. Dr. Perrier drafted the manuscript. Before any other test was administered, patients underwent clinical evaluation in the emergency department by the physicians in charge with the use of the Geneva score.10,15,16 The Geneva score is based on seven variables: age, previous deep venous thrombosis or pulmonary embolism, recent surgery, heart rate, the partial pressure of arterial oxygen, the partial pressure of arterial carbon dioxide, and the findings on chest radiography (e.g., band atelectasis or hemidiaphragm elevation). It allows the classification of patients into three categories of clinical probability of pulmonary embolism (low, intermediate, or high), corresponding to an increasing prevalence of pulmonary embolism. As previously described,10,16 the physicians in the emergency department could override the score by clinical judgment in case of disagreement. Clinical judgment was also used when the Geneva score could not be computed because of the unavailability of arterial-blood gas measurements while the patient was breathing ambient air. Sequential noninvasive tests were then performed and stratified according to the clinical probability of pulmonary embolism (Figure 1). In patients without a high clinical probability (i.e., either a low or intermediate probability), we measured plasma D-dimer levels by enzyme-linked immunosorbent assay (ELISA) and ruled out pulmonary embolism in patients with a level below the cutoff value of 500 μg per liter. Patients with a D-dimer level of 500 μg per liter or above underwent proximal venous-compression ultrasonography of the lower limbs and multidetector-row CT. CT that was positive for pulmonary embolism or ultrasonography that showed a deep venous thrombosis warranted anticoagulant treatment, whereas such therapy was withheld in patients in whom both tests were negative. In patients with a high clinical probability of pulmonary embolism, we did not obtain a D-dimer measurement, since the D-dimer test is negative in less than 10 percent of such patients and the probability of pulmonary embolism is still 12 to 23 percent when the test is negative in the subgroup that has a 65 to 80 percent prevalence of pulmonary embolism.17 These patients thus proceeded directly to CT and lower-limb ultrasonography. Patients in whom either test was positive were treated, but those with a high clinical probability and negative findings on both CT and ultrasonography proceeded to pulmonary angiography, and their cases were managed accordingly. The results of CT scanning were deemed inconclusive if technical problems (i.e., insufficient contrast enhancement of the pulmonary arteries or motion artifacts) precluded a definitive interpretation. Patients with isolated subsegmental pulmonary embolism (defined as CT evidence of embolism in a single subsegmental vessel) were also considered to have had an inconclusive CT, since the positive predictive value of that finding is low (25 percent in the Evaluation du Scanner Spiralé dans l'Embolie Pulmonaire study9). Patients with an inconclusive CT result proceeded to ventilation–perfusion lung scanning or pulmonary angiography. Ventilation–perfusion scanning confirmed pulmonary embolism in the case of a high-probability pattern18 and ruled it out when the result was normal19 or of low probability in a patient with a low clinical probability of pulmonary embolism and an absence of proximal deep venous thrombosis.20 In all other instances, ventilation–perfusion scanning was followed by pulmonary angiography for final adjudication. Figure 1. Flow Chart Summarizing the Diagnostic Process in the Study. PE denotes pulmonary embolism, CT multidetector-row computed tomography, US lower-limb compression ultrasonography, / ventilation–perfusion scanning, VTE venous thromboembolism, and TE thromboembolic. Diagnostic Studies Plasma D-dimer was assayed by an automated quantitative analyzer (rapid ELISA assay, Vidas DD Exclusion, BioMérieux).21 Lower-limb B-mode venous-compression ultrasonography was performed within 24 hours after admission by trained staff blinded to the results of CT. The examination consisted of a real-time B-mode examination of the common femoral and popliteal veins. The criterion for diagnosing deep-vein thrombosis was incomplete compressibility of the vein.22 The protocol for multidetector-row CT consisted of an evaluation of the pulmonary arteries up to and including the subsegmental vessels. The patients were examined during a breath hold or shallow breathing, depending on the degree of dyspnea. A clot was considered present if contrast material outlined an intraluminal defect or if a vessel was totally occluded by low-attenuation material. Four-slice multidetector-row CT was used in 89 percent of the patients, including all the patients in Angers and Paris and 81 of 137 patients (59 percent) in Geneva; the remaining 56 patients in Geneva were examined by 16-slice multidetector-row CT. The acquisition parameters for multidetector-row CT were injection of a total volume of 100 to 120 ml of nonionic contrast material (iodine concentration, 300 to 350 mg per milliliter) with a power injector at 3 to 5 ml per second; imaging 9 to 20 seconds after initiation of the contrast-material injection; scanning performed at 1.0 to 1.3 mm per section with a pitch of 1.25 to 1.75, 120 kV, and 115 to 260 mA; and reconstruction of images at 0.6-to-0.8-mm intervals. For obese patients, slice thickness was sometimes increased to 2.5 mm. The technique for performing and interpreting lung scanning and pulmonary angiography has been described elsewhere.23,24 Outcomes The main outcome was the proportion of patients with proximal deep venous thrombosis and negative findings on CT. The secondary outcome was an estimate of the three-month risk of thromboembolism if lower-limb ultrasonography had not been performed — in other words, the sum of the proportion of patients with deep venous thrombosis and negative CT results and of the three-month risk of thromboembolism among patients in whom pulmonary embolism was considered to have been ruled out by the initial diagnostic workup and anticoagulant therapy was not administered during follow-up. Diagnoses of venous thromboembolic events during follow-up were established with the usual criteria — for deep venous thrombosis, on the basis of abnormal results on ultrasonography; and for pulmonary embolism, ventilation–perfusion scanning showing a high-probability pattern or CT or angiography showing pulmonary embolism. Deaths were adjudicated as definitely caused by pulmonary embolism, definitely unrelated to pulmonary embolism, or possibly due to pulmonary embolism. A three-month risk of thromboembolism of 4 percent (upper limit of the 95 percent confidence interval) was considered acceptable, as in previous outcome studies.10,25,26 Three independent experts adjudicated the outcome events. Three-Month Follow-up Patients were followed up by their family physicians and were interviewed by telephone by one of the study coordinators at the end of the follow-up period. The family physician was contacted whenever a possible event was disclosed by the interim history, and charts were reviewed if a patient was readmitted to the hospital for any cause. Statistical Analysis The exact 95 percent confidence intervals for proportions were calculated from the binomial distribution with use of the Confidence Interval Analysis software program. Results Study Population The 756 patients had a mean (±SD) age of 60±19 years, and 60 percent were female. The characteristics of the patients are shown in Table 1. The overall prevalence of pulmonary embolism in this cohort was 26 percent (194 of 756 patients). Table 1. Characteristics of the 756 Patients in the Study. Diagnostic Workup The diagnostic workup is detailed in Figure 1, and the respective diagnostic yield of the criteria used in this series is summarized in Table 2. Table 2. Yield of the Diagnostic Criteria Used in the Series. Patients with a High Clinical Probability of Pulmonary Embolism CT scanning showed a pulmonary embolism in 78 of the 82 patients (95 percent) who had a high clinical probability of pulmonary embolism; 37 of these 78 patients had proximal deep venous thrombosis (47 percent; 95 percent confidence interval, 37 to 58). Only one patient had proximal deep venous thrombosis and negative findings on CT, and that patient was treated. The other three patients had negative findings on both ultrasonography and CT, and subsequent angiography was negative in all three. Patients without a High Clinical Probability of Pulmonary Embolism Among the 674 patients without a high clinical probability of pulmonary embolism, the D-dimer level was below 500 μg per liter in 232 patients (34 percent; 95 percent confidence interval, 31 to 38). The remaining patients proceeded to CT and venous ultrasonography. CT showed pulmonary embolism in 109 patients, of whom 36 also had a deep venous thrombosis (33 percent; 95 percent confidence interval, 25 to 42), and they all were treated. CT scanning and ultrasonography were negative in 318 patients. Two patients with negative CT scans had a proximal deep venous thrombosis (0.6 percent; 95 percent confidence interval, 0.2 to 2.2) and were treated. Among 13 patients, the CT scan was considered inconclusive, according to the study criteria. In 11 patients, the scan was technically inadequate for interpretation. Further testing established pulmonary embolism in three patients and ruled it out in eight patients, who were not treated (Figure 1 and Table 2). In the other two patients, CT revealed an isolated subsegmental embolus. One of these patients — who had a low clinical probability of pulmonary embolism, a low-probability ventilation–perfusion lung scan, and no proximal deep venous thrombosis — was not treated, whereas the other was treated with anticoagulants on the basis of a positive angiogram. The overall proportion of patients (both those without a high probability of pulmonary embolism and those with a high probability) who had deep venous thrombosis and negative findings on CT was 3 of 324 (0.9 percent; 95 percent confidence interval, 0.3 to 2.7). Anatomical Distribution of Emboli The anatomical distribution of the pulmonary emboli, according to the most proximal vessel that was affected and to the clinical probability category, is detailed in Table 3. Table 3. Anatomical Distribution of Pulmonary Emboli Visualized by CT, According to the Most Proximal Level of the Pulmonary Arterial Tree. Follow-up and Outcomes Pulmonary Embolism Ruled Out by Initial Diagnostic Workup In all 4 patients lost to follow-up (0.5 percent of the entire cohort of 756), pulmonary embolism had been ruled out by the initial diagnostic workup; 2 patients without a high clinical probability of pulmonary embolism had a negative D-dimer assay, and 2 patients had negative findings on CT and lower-limb ultrasonography. During follow-up, 35 of the 562 patients in whom pulmonary embolism had been ruled out received anticoagulation therapy for reasons other than venous thromboembolism (atrial fibrillation or flutter, 26 patients; cardiomyopathy, 2; and other indications, 7), leaving 523 patients for the assessment of the three-month thromboembolic risk. There were no thromboembolic events among the 220 patients with a normal D-dimer level who did not receive anticoagulation therapy (0 percent; 95 percent confidence interval, 0 to 2.7). Of the patients without a high probability of pulmonary embolism who had negative findings on CT scanning and ultrasonography, three patients had a thromboembolic event, and 2 of the 26 deaths in this group were adjudicated as possibly due to pulmonary embolism (Table 4). Therefore, the three-month risk of thromboembolism among the 292 patients who did not receive anticoagulation therapy during follow-up was 1.7 percent (95 percent confidence interval, 0.7 to 3.9). The overall three-month risk of thromboembolism among the 523 patients who did not have pulmonary embolism and were not receiving treatment was 1.0 percent (95 percent confidence interval, 0.4 to 2.2). With the addition of the three patients with proximal deep venous thrombosis and negative findings on CT scanning, the maximum three-month risk of thromboembolism would have been 1.5 percent (95 percent confidence interval, 0.8 to 3.0) if ultrasonography had not been included in the diagnostic workup. There were 24 deaths that were not related to venous thromboembolism in this group, which were caused by cancer (18 patients), respiratory failure (3), septic shock (2), and cardiac disease (1). Table 4. Thromboembolic Events during the Three-Month Follow-up among Five Patients in Whom Pulmonary Embolism Was Initially Ruled Out. Pulmonary Embolism Indicated by Initial Diagnostic Workup Four of the 194 patients with pulmonary embolism (2.1 percent; 95 percent confidence interval, 0.9 to 4.5) had recurrent venous thromboembolism. There were 11 deaths (5.7 percent; 95 percent confidence interval, 3.2 to 9.9) from cancer (5), septic shock (2), recurrent pulmonary embolism (2), initial pulmonary embolism (1), and an indeterminate cause (1). Discussion This study shows that the proportion of patients with proximal deep venous thrombosis despite negative findings on multidetector CT is very low (0.9 percent; 95 percent confidence interval, 0.3 to 2.7). Therefore, the improvement of the overall detection rate of pulmonary embolism by venous ultrasonography was marginal in this series, and the three-month thromboembolic risk in patients left untreated if pulmonary embolism had been ruled out on the sole basis of a negative multidetector CT scan would have been 1.5 percent (95 percent confidence interval, 0.9 to 2.7), similar to that of pulmonary angiography11 and other recent outcome studies.9,10,25,26 This raises the possibility that the use of ELISA measurement of plasma D-dimer levels and multidetector CT scanning might safely rule out pulmonary embolism in patients without a high probability of pulmonary embolism without performing lower-limb ultrasonography. Since ultrasonography is costly and labor-intensive and not all centers have access to the technique, forfeiting ultrasonography would possibly reduce costs. It would also mean that small centers with equipment to perform multidetector CT but not venous ultrasonography could safely work up patients with suspected pulmonary embolism without a referral. The advent of an imaging technique allowing the visualization of very small peripheral emboli12,13 raises the concern of overdiagnosis. In this study, we could not calculate the false positive rate of multidetector-row CT since scans showing pulmonary embolism were not verified by other tests. Nevertheless, the anatomical distribution of emboli in the pulmonary arterial tree (Table 3) was similar to that in our previous series conducted with the use of single-detector CT,7 except for the presence of multiple subsegmental clots in 7 percent of patients. That proportion is similar to that of the landmark Prospective Investigation of Pulmonary Embolism Diagnosis study, which showed subsegmental emboli in 6 percent of patients with the use of pulmonary angiography.18 Isolated subsegmental emboli were identified in only 2 of the 191 patients with CT evidence of venous thromboembolism (1.0 percent), as compared with 12 of 290 patients in the ESSEP study.9 The overall prevalence of pulmonary embolism in this cohort (26 percent) has only slightly risen as compared with a previous multicenter study from our group (23 percent).10 Therefore, our findings do not support the fear that multidetector CT technology entails a substantial risk of overdiagnosis. This series adds to the body of data on the performance of an already well-validated ELISA D-dimer assay in suspected pulmonary embolism.10,25,27 No thromboembolic event occurred during the follow-up period in the 220 patients with a normal D-dimer test who were left untreated throughout. Hence, pooled data from our two previous studies10,25 and this series provide a precise estimate of the three-month thromboembolic risk in patients in whom pulmonary embolism is ruled out on the basis of a normal D-dimer test: 0 of 643 patients (0 percent; 95 percent confidence interval, 0 to 0.4). Our study has some limitations. First, generalization of our findings might be a concern, since 25 percent of screened patients were excluded. However, the characteristics of the patients who were included in this cohort are representative of those among patients admitted to emergency departments for suspected pulmonary embolism in all recent series.10,25,26,28 Moreover, none of the 73 patients who were excluded because of protocol violations (7 percent) who had negative findings on CT scanning had a thromboembolic event during follow-up. Second, this series is not a true outcome study, since venous ultrasonography was performed in all patients with an abnormal D-dimer level, and those with deep venous thrombosis and negative findings on CT were treated with anticoagulant therapy. Our results should be confirmed in a proper outcome study in which the decision to withhold anticoagulation would be made on the basis of negative findings on multidetector-row CT alone in patients with an abnormal D-dimer level. In summary, our study shows that the proportion of patients with deep venous thrombosis despite negative findings on multidetector-row CT scanning is below 1 percent and that ruling out pulmonary embolism with the use of D-dimer measurement and multidetector CT would entail a three-month thromboembolic risk of around 1.5 percent. This raises the possibility that such a strategy might be safe in patients who are admitted to emergency centers for suspected pulmonary embolism, a hypothesis that should now be evaluated in a proper outcome study. Supported by a grant from the Hirsch Fund of the University of Geneva. Dr. Perrier, Dr. Le Gal, and Dr. Roy report having served as consultants for BioMérieux. Dr. Bounameaux, Dr. Sanchez, Dr. Meyer, Dr. Davido, Dr. Gourdier, Dr. Furber, Dr. Revel, and Dr. Howarth have no relationships with companies that make products relevant to this study. We are indebted to Catherine Ridereau, Georges Leftheriotis, Catherine Ternisien, Alain Dauver, and Alain Delhumeau in Angers; to Philippe de Moerloose, Thierry Merminod, Marc Righini, Dominique Didier, and Pascal Bachmann in Geneva; and to all physicians in the departments of emergency, radiology, angiology and hemostasis, and nuclear medicine in Paris, Angers, and Geneva; to Patrick Bandelier and Ariane Testuz in Geneva, Nicole Sorin and Céline Priou in Angers, and Delphine Wermert in Paris for their help in data collection; and to all the residents of the emergency departments of the three centers for their invaluable collaboration throughout the study. Source Information From the Service of General Internal Medicine (A.P.) and the Division of Angiology and Hemostasis (G.L.G., H.B.), Department of Internal Medicine, and the Service of Radiodiagnosis and Interventional Radiology, Department of Medical Radiology and Informatics (N.H.), Geneva Faculty of Medicine and Geneva University Hospital, Geneva; the Emergency Department (P.-M.R.), the Service of Radiology (A.-L.G.), and the Service of Cardiology (A.F.), Angers University Hospital, Angers, France; and the Service of Pneumology (O.S., G.M.), the Service of Radiology (M.-P.R.), and the Emergency Department (A.D.), H?pital Européen Georges-Pompidou, Paris. Address reprint requests to Dr. Perrier at the Service of General Internal Medicine, Geneva University Hospital, Rue Micheli-du-Crest 24, CH-1211 Geneva 14, Switzerland, or at arnaud.perrier@medecine.unige.ch. References British Thoracic Society guidelines for the management of suspected acute pulmonary embolism. Thorax 2003;58:470-483. Fedullo PF, Tapson VF. The evaluation of suspected pulmonary embolism. N Engl J Med 2003;349:1247-1256. Kruip MJ, Leclercq MG, van der Heul C, Prins MH, Buller HR. Diagnostic strategies for excluding pulmonary embolism in clinical outcome studies: a systematic review. Ann Intern Med 2003;138:941-951. Goldhaber SZ. Pulmonary embolism. Lancet 2004;363:1295-1305. Rathbun SW, Raskob GE, Whitsett TL. Sensitivity and specificity of helical computed tomography in the diagnosis of pulmonary embolism: a systematic review. Ann Intern Med 2000;132:227-232. Mullins MD, Becker DM, Hagspiel KD, Philbrick JT. The role of spiral volumetric computed tomography in the diagnosis of pulmonary embolism. Arch Intern Med 2000;160:293-298. Perrier A, Howarth N, Didier D, et al. Performances of helical computed tomography in unselected outpatients with suspected pulmonary embolism. Ann Intern Med 2001;135:88-97. van Strijen MJL, de Monye W, Kieft GJ, Pattynama PMT, Prins MH, Huisman MV. Accuracy of single-detector spiral CT in the diagnosis of pulmonary embolism: a prospective multicenter cohort study of consecutive patients with abnormal perfusion scintigraphy. J Thromb Haemost 2005;3:17-25. Musset D, Parent F, Meyer G, et al. Diagnostic strategy for patients with suspected pulmonary embolism: a prospective multicentre outcome study. Lancet 2002;360:1914-1920. Perrier A, Roy PM, Aujesky D, et al. Diagnosing pulmonary embolism in outpatients with clinical assessment, D-dimer measurement, venous ultrasound, and helical computed tomography: a multicenter management study. Am J Med 2004;116:291-299. van Beek EJ, Brouwerst EM, Song B, Stein PD, Oudkerk M. Clinical validity of a normal pulmonary angiogram in patients with suspected pulmonary embolism -- a critical review. Clin Radiol 2001;56:838-842. Ghaye B, Szapiro D, Mastora I, et al. Peripheral pulmonary arteries: how far in the lung does multi-detector row spiral CT allow analysis? Radiology 2001;219:629-636. Schoepf UJ, Goldhaber SZ, Costello P. Spiral computed tomography for acute pulmonary embolism. Circulation 2004;109:2160-2167. Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron 1976;16:31-41. Wicki J, Perneger TV, Junod A, Bounameaux H, Perrier A. Assessing clinical probability of pulmonary embolism in the emergency ward: a simple score. Arch Intern Med 2001;161:92-97. Chagnon I, Bounameaux H, Aujesky D, et al. Comparison of two clinical prediction rules and implicit assessment for suspected pulmonary embolism. Am J Med 2002;113:269-275. Righini M, Aujesky D, Roy PM, et al. Clinical usefulness of D-dimer depending on clinical probability and cutoff value in outpatients with suspected pulmonary embolism. Arch Intern Med 2004;164:2483-2487. The PIOPED Investigators. Value of the ventilation/perfusion scan in acute pulmonary embolism: results of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). JAMA 1990;263:2753-2759. Hull RD, Raskob GE, Coates G, Panju AA. Clinical validity of a normal perfusion lung scan in patients with suspected pulmonary embolism. Chest 1990;97:23-26. Perrier A, Miron MJ, Desmarais S, et al. Using clinical evaluation and lung scan to rule out suspected pulmonary embolism: is it a valid option in patients with normal results of lower-limb venous compression ultrasonography? Arch Intern Med 2000;160:512-516. de Moerloose P, Desmarais S, Bounameaux H, et al. Contribution of a new, rapid, individual and quantitative automated D-dimer ELISA to exclude pulmonary embolism. Thromb Haemost 1996;75:11-13. Lensing AWA, Prandoni P, Brandjes D, et al. Detection of deep-vein thrombosis by real-time B-mode ultrasonography. N Engl J Med 1989;320:342-345. Bounameaux H, Cirafici P, de Moerloose P, et al. Measurement of D-dimer in plasma as diagnostic aid in suspected pulmonary embolism. Lancet 1991;337:196-200. Perrier A, Bounameaux H, Morabia A, et al. Diagnosis of pulmonary embolism by a decision analysis-based strategy including clinical probability, D-dimer levels, and ultrasonography: a management study. Arch Intern Med 1996;156:531-536. Perrier A, Desmarais S, Miron MJ, et al. Non-invasive diagnosis of venous thromboembolism in outpatients. Lancet 1999;353:190-195. Wells PS, Anderson DR, Rodger M, et al. Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and D-dimer. Ann Intern Med 2001;135:98-107. Kruip MJ, Slob MJ, Schijen JH, van der Heul C, Buller HR. Use of a clinical decision rule in combination with D-dimer concentration in diagnostic workup of patients with suspected pulmonary embolism: a prospective management study. Arch Intern Med 2002;162:1631-1635. Wells PS, Ginsberg JS, Anderson DR, et al. Use of a clinical model for safe management of patients with suspected pulmonary embolism. Ann Intern Med 1998;129:997-1005....查看详细 (32645字节)
☉ 11325822:Hemochromatosis and Iron-Overload Screening in a Racially Diverse Population
ABSTRACT Background Iron overload and hemochromatosis are common, treatable conditions. HFE genotypes, levels of serum ferritin, transferrin saturation values, and self-reported medical history were studied in a multiethnic primary care population. Methods Participants were recruited from primary care practices and blood-drawing laboratories. Blood samples were tested for transferrin saturation, serum ferritin, and C282Y and H63D mutations of the HFE gene. Before genetic screening, participants were asked whether they had a history of medical conditions related to iron overload. Results Of the 99,711 participants, 299 were homozygous for the C282Y mutation. The estimated prevalence of C282Y homozygotes was higher in non-Hispanic whites (0.44 percent) than in Native Americans (0.11 percent), Hispanics (0.027 percent), blacks (0.014 percent), Pacific Islanders (0.012 percent), or Asians (0.000039 percent). Among participants who were homozygous for the C282Y mutation but in whom iron overload had not been diagnosed (227 participants), serum ferritin levels were greater than 300 μg per liter in 78 of 89 men (88 percent) and greater than 200 μg per liter in 79 of 138 women (57 percent). Pacific Islanders and Asians had the highest geometric mean levels of serum ferritin and mean transferrin saturation despite having the lowest prevalence of C282Y homozygotes. There were 364 participants in whom iron overload had not been diagnosed (29 C282Y homozygotes) who had a serum ferritin level greater than 1000 μg per liter. Among men, C282Y homozygotes and compound heterozygotes were more likely to report a history of liver disease than were participants without HFE mutations. Conclusions The C282Y mutation is most common in whites, and most C282Y homozygotes have elevations in serum ferritin levels and transferrin saturation. The C282Y mutation does not account for high mean serum ferritin levels and transferrin saturation values in nonwhites. Iron overload can be associated with a wide range of genetic and environmental factors and can lead to parenchymal damage of organs. Homozygosity for the C282Y mutation of the HFE gene is associated with susceptibility to iron overload and is a common genetic mutation, occurring in 0.3 to 0.5 percent of white persons of northern European descent.1,2 Phlebotomy treatment can prevent some of the major complications of iron overload, and patients have normal life expectancy if they are treated before organ damage occurs.3 Iron overload can occur in nonwhites and may be related to as-yet-undiscovered genetic mutations, environmental factors, or both.4,5,6,7,8,9 The Hemochromatosis and Iron Overload Screening (HEIRS) study was designed to evaluate the prevalence, genetic and environmental determinants, and potential clinical, personal, and societal effects of iron overload and hemochromatosis in a multicenter, multiethnic sample of 101,168 primary care adults 25 years of age or older. This article reports findings from the first, or screening, stage of the study. Methods Study Participants A detailed description of the HEIRS study has previously been reported.10 Participants were recruited over a two-year period at five field centers (Washington, D.C.; Birmingham, Alabama; Irvine, California; Portland, Oregon, and Honolulu; and London, Ontario, Canada). Our target population was primary care patients, identified through primary care clinics and medical blood-drawing laboratories. Both patients and other persons accompanying the patient were potential participants. We did no advertising to recruit participants. Eligibility criteria included an age of 25 years or older and an ability to understand the informed-consent document. Participants were asked how they heard about the study and whether they had previously been given a diagnosis of iron overload or hemochromatosis. Measurements included spectrophotometric determination of serum iron and unsaturated iron-binding capacity, turbidimetric immunoassay of serum ferritin (Hitachi 911, Roche), and calculated transferrin saturation on nonfasting blood samples. HFE C282Y and H63D alleles were determined from spots of whole blood with the use of a modification of the Invader assay (Third Wave Technologies) that increases the allele-specific fluorescent signal by including 12 cycles of locus-specific polymerase chain reaction before the cleavase reaction. Absence of a detectable C282Y or H63D mutation was designated as wild type. Race or ethnic group was determined by self-reported answers to two questions, one regarding Hispanic background and one offering a nonexclusive choice of five racial groups: white, black, Asian, Pacific Islander, and American Indian. Participants affirming Hispanic background were classified as Hispanic; otherwise, they were classified according to their response to the question about race. Before receiving the results of any genetic test, all participants were asked whether they had a history of liver disease, diabetes, arthritis, congestive heart failure, impotence, or infertility. Participants with elevations in transferrin saturation and ferritin levels and all C282Y homozygotes were invited to a clinical examination at a later stage of the study. A total of 101,168 participants had complete data on serum ferritin levels, transferrin saturation, and HFE C282Y and H63D alleles, and 333 participants with complete data were homozygous for the C282Y mutation. After 1457 participants (including 34 C282Y homozygotes) who reported hearing about the study exclusively from a participating family member were excluded from all analyses, 99,711 participants remained. For the analyses involving serum ferritin levels and transferrin saturation, an additional 1182 participants who reported a previous diagnosis of hemochromatosis or iron overload were also excluded to remove possible effects of earlier phlebotomy therapy on iron tests and ascertainment bias, leaving 98,529 participants for these analyses. For the analyses presented, we assumed that all persons were unrelated. Statistical Analysis Deviations of observed frequencies of HFE genotypes from Hardy–Weinberg proportions were assessed by exact test11 in the total sample and stratified according to race or ethnic group and field center. The frequencies of HFE genotypes were calculated separately in each stratum of race or ethnic group. To account for higher participation rates among C282Y homozygotes, maximum likelihood estimates of the frequencies of HFE genotypes were calculated under the assumption of Hardy–Weinberg proportions in the participants within each stratum of race or ethnic group who were not homozygous for the C282Y mutation, regardless of the number of observed C282Y homozygotes. Confidence intervals for frequencies of HFE genotypes were calculated on the basis of inverting the score test for a multinomial proportion.12 Odds ratios for the effect of HFE genotype on self-reported medical history were estimated with the use of logistic regression. Estimates were adjusted for age, field center, and race or ethnic group. Age was modeled as a set of indicator variables for each year of age, except that all ages above 80 years were grouped. Comparisons of pairs of means among the 12 sex and genotype combinations were performed with the use of two-way analysis of variance with Scheffé's method for multiple comparisons. For serum ferritin levels, analysis was done after log transformation, and the geometric mean and antilog of the first and third quartiles are reported. For transferrin saturation, mean and standard deviation are reported. Participants with complete data on transferrin saturation, serum ferritin levels, and HFE genotype were included in this analysis. Serum ferritin levels below the detectable limit of 15 μg per liter were imputed as 7.5 μg per liter. Transferrin saturation values reported as less than 3 percent were imputed as 1.5 percent. Results Study Population The participants included 62,749 women and 36,962 men. The predominance of female participants is representative of primary care populations. Women also have a higher participation rate than men in medical research studies. The median age was 50 years (range, 25 to 100). Among men, 23 percent were 25 to 39 years of age, 23 percent were 40 to 49, 23 percent were 50 to 59, 18 percent were 60 to 69, and 13 percent were older than 69. Among women, 27 percent were 25 to 39 years of age, 24 percent were 40 to 49, 24 percent were 50 to 59, 15 percent were 60 to 69, and 10 percent were older than 69. According to self-identified race or ethnic group, the sample included 44 percent white participants, 27 percent black, 13 percent Asian, 13 percent Hispanic, 0.7 percent Pacific Islander, 0.7 percent Native American, and 2 percent of mixed or unknown race. Genotypic Variations Of the 99,711 participants, 299 were homozygous for the C282Y mutation (Table 1). The estimated prevalence of C282Y homozygotes was highest in whites (0.44 percent; 95 percent confidence interval, 0.42 to 0.47) and lowest in Asians (0.000039 percent; 95 percent confidence interval, 0.000015 to 0.00010), Pacific Islanders (0.012 percent; 95 percent confidence interval, 0.0043 to 0.032), and blacks (0.014 percent; 95 percent confidence interval, 0.012 to 0.017); among the latter three groups, the vast majority of participants (>88 percent) had the wild-type genotype. The H63D/+ genotype was common in whites (24 percent), Native Americans (20 percent), and Hispanics (18 percent). In whites, the C282Y/+ genotype was also quite common (10 percent). Table 1. Prevalence of HFE C282Y and H63D Genotypes According to Race or Ethnic Group. These estimates of genotype frequency assume Hardy–Weinberg proportions in the groups of participants who were not homozygous for the C282Y mutation. The estimation procedure accounts for higher participation rates in C282Y homozygotes, who were observed more frequently than expected (P 0.12 for all). Similarly, among female C282Y homozygotes, the geometric mean serum ferritin level (212 μg per liter) was above the screening criteria of 200 μg per liter and significantly greater than the levels among female participants in all other genotype groups (range, 64 to 85 μg per liter; P0.80 for all). C282Y homozygotes had markedly higher transferrin saturation and serum ferritin levels, as expected. The transferrin saturation values according to sex gradually increased, from HFE wild type, to H63D/+, to C282Y/+, to H63D homozygote, and to compound heterozygote. Pairwise comparisons of the genotype means according to sex (Figure 1) all showed a significant difference (P<0.01). Descriptive statistics of transferrin saturation and ferritin levels according to race or ethnic group and sex are shown in Table 2. The threshold values used in this table correspond to those used by Ioannou et al.15 (although we have added ferritin levels greater than 1000 μg per liter) and those used in the HEIRS study to define elevated status. Table 2. Prevalence of Elevated Iron Levels According to Race or Ethnic Group. Among men, a history of liver disease was reported more often in C282Y homozygotes (odds ratio, 3.3; 95 percent confidence interval, 1.5 to 7.2; P=0.003) and compound heterozygotes (odds ratio, 1.7; 95 percent confidence interval, 1.0 to 2.7; P=0.05) than in participants without HFE mutations (Table 3). There were no significant differences in the incidence of self-reported diabetes between C282Y homozygotes and participants without HFE mutations. Among men, H63D homozygotes were more likely to report a history of arthritis (odds ratio, 1.3; 95 percent confidence interval, 1.0 to 1.6) than were participants without HFE mutations. Among women, H63D homozygotes were more likely to report a history of heart disease (odds ratio, 1.5; 95 percent confidence interval, 1.0 to 2.1) than were participants without HFE mutations. Table 3. Association between HFE Genotypes and Medical Conditions Related to Iron Overload. Discussion The HEIRS study included a large group of ethnically and geographically diverse participants. Asberg et al. studied 65,238 Norwegians in a white population,16 and Beutler et al. studied 41,038 participants from Kaiser San Diego, including 4 percent blacks, 4 percent Asians, and 10 percent Hispanics.17 Steinberg et al. studied HFE mutations in 5171 anonymous samples from the National Health and Nutrition Examination Survey, but no iron tests were reported for correlations between genotype and phenotype.18 HFE mutations are most common in white populations, a finding consistent with the theory that hemochromatosis originated in northern Europe.18,19,20 The frequency of C282Y genotypes is much lower in nonwhite populations. Despite our efforts to minimize the influence of family members of homozygotes, it is possible that they are still overrepresented in our analysis. In the HEIRS study, the prevalence of C282Y genotypes among Hispanics was higher than among Asians or blacks but lower than among whites. Previous studies have suggested a higher prevalence of C282Y mutations in Hispanic populations than in nonwhite populations.17 Although H63D genotypes are more common than C282Y genotypes in all ethnic or racial groups and H63D has been considered to be an older mutation that possibly originated in Asia,21 H63D mutations in our study were less common among Asians than among most other racial or ethnic groups. The prevalence of H63D genotypes was highest among whites. The prevalence among Hispanics was lower than among whites but considerably higher than among blacks and Asians. Among Asians, the prevalence of H63D genotypes was higher than among blacks but the prevalence of C282Y genotypes was lower than among blacks. Serum ferritin levels and transferrin saturation were significantly higher in C282Y homozygotes than in those with other genotypes. In participants who were homozygous for the C282Y mutation but in whom iron overload had not previously been diagnosed, an elevated ferritin level was found in 88 percent of men and 57 percent of women, suggesting that many adults who are homozygous for the C282Y mutation may have iron overload. The prevalence of self-reported liver disease was significantly greater in male C282Y homozygotes and compound heterozygotes than in participants without HFE mutations. Liver disease is one of the most well-established of the complications of iron overload, and iron-depletion therapy by means of phlebotomy has been shown to stabilize liver disease and prevent the progression to cirrhosis, which adversely affects long-term survival.3 The self-reported history of liver disease is nonspecific and could encompass a broad range of liver diseases, including alcoholic liver disease, chronic viral hepatitis, and fatty liver, but we do not believe that these would be overrepresented in the C282Y homozygotes.22,23 We believe that the increased self-reporting of liver disease in C282Y homozygotes points to a potential opportunity to treat and prevent the progression of liver disease. Of 98,529 participants who had not previously been diagnosed with hemochromatosis or iron overload, 364 (0.4 percent) had a serum ferritin level greater than 1000 μg per liter, and previous studies of C282Y homozygotes have shown that the risk of cirrhosis increases as the ferritin level increases to above 1000 μg per liter.13,14 However, this subgroup with a serum ferritin level greater than 1000 μg per liter contained only 29 C282Y homozygotes. Our observation that Pacific Islanders are much more likely to have serum ferritin levels greater than 1000 μg per liter than whites has not to our knowledge been previously reported (Table 2). The increase in self-reported arthritis in male H63D homozygotes and heart disease in female H63D homozygotes (Table 3) cannot readily be explained by iron overload, since most participants with this genotype had normal serum ferritin levels. Arthritis is the symptom in hemochromatosis that has not shown a relationship with body iron stores.24 These observations may be related to linkage disequilibrium in the HLA complex. The observation that self-reported diabetes is not more common in C282Y homozygotes (Table 3) is surprising, since hemochromatosis was originally called bronze diabetes. However, the participants who were excluded from our study because their iron overload had previously been diagnosed may have had more advanced disease. Diabetes has also become more common in the general population with the high prevalence of obesity. Our findings are similar to the findings of Beutler, who also found an increase in the prevalence of liver disease but no increase in diabetes, arthritis, or heart disease in C282Y homozygotes.17 Our results also illustrate the nonspecific nature of many of the symptoms that have been attributed to hemochromatosis. In C282Y homozygotes with normal serum ferritin levels, iron accumulation may develop over time, but other studies have shown that a progressive rise in iron stores is not inevitable.25,26,27,28 Elevated iron levels were more common in participants with the C282Y/H63D and H63D/H63D genotypes than in participants without HFE mutations, although the mean transferrin saturation and ferritin levels were below the upper limit of the reference range for those with all genotypes except C282Y homozygotes. Nongenetic factors also contribute to the differences between ethnic and racial groups. Elevations in ferritin levels are commonly seen in patients who have obesity-related steatohepatitis,29 chronic alcohol consumption, or hepatitis B or C.30,31,32 Therefore, the results of our screening should not be considered indicative of the prevalence of iron overload in this primary care population. Supported by the National Heart, Lung, and Blood Institute (NHLBI), in conjunction with the National Human Genome Research Institute; by contracts N01-HC-05185 (University of Minnesota), N01-HC-05186 (Howard University), N01-HC-05188 (University of Alabama at Birmingham), N01-HC-05189 (Kaiser Permanente Center for Health Research), N01-HC-05190 (University of California, Irvine), N01-HC-05191 (London Health Sciences Centre), and N01-HC-05192 (Wake Forest University); and by grants from the Howard University General Clinical Research Center (M01-RR10284), from the NHLBI and the Office of Minority Health (UH1-HL03679-05), and from the National Center for Research Resources (M01-RR00827) to the University of California, Irvine, and from the University of Alabama at Birmingham General Clinical Research Center (M01-RR00032) to the University of Alabama at Birmingham. We are indebted to Dr. Jean MacCluer, Southwest Foundation for Biomedical Research, for contributions to the design of this study. * Members of the HEIRS study are listed in the Appendix. Source Information From the Department of Medicine, London Health Sciences Centre, London, Ont., Canada (P.C.A.); the Department of Public Health Sciences, Wake Forest University School of Medicine, Winston-Salem, N.C. (D.M.R., B.M.S.); Southern Iron Disorders Center, Birmingham, Ala. (J.C.B.); Epidemiology Division (C.E.M.) and Division of Hematology and Oncology (G.D.M.), Department of Medicine, University of California, Irvine; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis (J.H.E., C.L.-F.); Veterans Affairs Long Beach Healthcare System, Long Beach, Calif. (G.D.M.); Department of Medicine, Howard University, Washington, D.C. (F.W.D., V.R.G.); Departments of Microbiology, Medicine, and Epidemiology and International Health, University of Alabama at Birmingham, Birmingham (R.T.A.); Kaiser Permanente Center for Health Research, Portland, Oreg. (E.L.H.), Department of Epidemiology and Biostatistics, University of Western Ontario, London, Canada (M.S.); Kaiser Permanente Center for Health Research, Honolulu (J.L.H.); National Human Genome Research Institute, Bethesda, Md. (E.T.); and the Epidemiology and Biometry Program, National Heart, Lung, and Blood Institute, Bethesda, Md. (P.S.). Address reprint requests to Dr. Adams at the Department of Medicine, London Health Sciences Centre, 339 Windermere Rd., London, ON N6A 5A5, Canada, or at padams@uwo.ca. References Bacon BR. Hemochromatosis: diagnosis and management. Gastroenterology 2001;120:718-725. Pietrangelo A. Hereditary hemochromatosis -- a new look at an old disease. N Engl J Med 2004;350:2383-2397. Niederau C, Fischer R, Purschel A, Stremmel W, Haussinger D, Strohmeyer G. Long-term survival in patients with hereditary hemochromatosis. Gastroenterology 1996;110:1107-1119. Gordeuk VR, Boyd RD, Brittenham GM. Dietary iron overload persists in rural sub-Saharan Africa. Lancet 1986;1:1310-1313. Gordeuk V, Caleffi A, Corradini E, et al. Iron overload in Africans and African-Americans and a common mutation in the SCL40A1 (ferroportin 1) gene. Blood Cells Mol Dis 2003;31:299-304. Barton JC, Acton RT, Rivers CA, et al. Genotypic and phenotypic heterogeneity of African Americans with primary iron overload. Blood Cells Mol Dis 2003;31:310-319. Eason RJ, Adams PC, Aston CE, Searle J. Familial iron overload with possible autosomal dominant inheritance. Aust N Z J Med 1990;20:226-230. Oliver M, Scully L, Guiraudon C, Adams PC. Non-HLA-linked hemochromatosis in a Chinese woman. Dig Dis Sci 1995;40:1589-1591. Kng C, Ng FH, Ng WF, et al. A Chinese patient with non-HFE linked iron overload. J Clin Gastroenterol 2001;33:69-71. McLaren CE, Barton JC, Adams PC, et al. Hemochromatosis and Iron Overload Screening (HEIRS) study design for an evaluation of 100,000 primary care-based adults. Am J Med Sci 2003;325:53-62. Weir BS. Genetic data analysis II: methods for discrete population genetic data. Sunderland, Mass.: Sinauer, 1996. Cox DR, Hinkley DV. Theoretical statistics. London: Chapman & Hall, 1974. Beaton M, Guyader D, Deugnier Y, Moirand R, Chakrabarti S, Adams P. Non-invasive prediction of cirrhosis in C282Y-linked hemochromatosis. Hepatology 2002;36:673-678. Morrison ED, Brandhagen DJ, Phatak PD, et al. Serum ferritin level predicts advanced hepatic fibrosis among U.S. patients with phenotypic hemochromatosis. Ann Intern Med 2003;138:627-633. Ioannou GN, Dominitz JA, Weiss NS, Heagerty PJ, Kowdley KV. The effect of alcohol consumption on the prevalence of iron overload, iron deficiency, and iron deficiency anemia. Gastroenterology 2004;126:1293-1301. Asberg A, Hveem K, Thorstensen K, et al. Screening for hemochromatosis: high prevalence and low morbidity in an unselected population of 65,238 persons. Scand J Gastroenterol 2001;36:1108-1115. Beutler E, Felitti VJ, Koziol JA, Ho NJ, Gelbart T. Penetrance of the 845G to A (C282Y) HFE hereditary haemochromatosis mutation in the USA. Lancet 2002;359:211-218. Steinberg KK, Cogswell ME, Chang JC, et al. Prevalence of C282Y and H63D mutations in the hemochromatosis (HFE) gene in the United States. JAMA 2001;285:2216-2222. Lucotte G, Dieterlen F. A European allele map of the C282Y mutation of hemochromatosis: Celtic versus Viking origin of the mutation? Blood Cells Mol Dis 2003;31:262-267. Merryweather-Clarke AT, Pointon JJ, Jouanolle AM, Rochette J, Robson KJ. Geography of HFE C282Y and H63D mutations. Genet Test 2000;4:183-198. Rochette J, Pointon JJ, Fisher CA, et al. Multicentric origin of hemochromatosis gene (HFE) mutations. Am J Hum Genet 1999;64:1056-1062. Adams PC, Agnew S. Alcoholism in hereditary hemochromatosis revisited: prevalence and clinical consequences among homozygous siblings. Hepatology 1996;23:724-727. Bacon BR, Olynyk JK, Brunt EM, Britton RS, Wolff RK. HFE genotype in patients with hemochromatosis and other liver diseases. Ann Intern Med 1999;130:953-962. Adams PC, Deugnier Y, Moirand R, Brissot P. The relationship between iron overload, clinical symptoms, and age in 410 patients with genetic hemochromatosis. Hepatology 1997;25:162-166. Yamashita C, Adams PC. Natural history of the C282Y homozygote for the hemochromatosis gene (HFE) with a normal serum ferritin level. Clin Gastroenterol Hepatol 2003;1:388-91. Olynyk JK, Hagan SE, Cullen DJ, Beilby J, Whittall DE. Evolution of untreated hereditary hemochromatosis in the Busselton population: a 17-year study. Mayo Clin Proc 2004;79:309-313. Andersen RV, Tybjaerg-Hansen A, Appleyard M, Birgens H, Nordestgaard BG. Hemochromatosis mutations in the general population: iron overload progression rate. Blood 2004;103:2914-2919. Olynyk JK, Cullen DJ, Aquilia S, Rossi E, Summerville L, Powell LW. A population-based study of the clinical expression of the hemochromatosis gene. N Engl J Med 1999;341:718-724. Angulo P, Keach JC, Batts KP, Lindor KD. Independent predictors of liver fibrosis in patients with nonalcoholic steatohepatitis. Hepatology 1999;30:1356-1362. Di Bisceglie AM, Axiotis CA, Hoofnagle JH, Bacon BR. Measurements of iron status in patients with chronic hepatitis. Gastroenterology 1992;102:2108-2113. Riggio O, Montagnese F, Fiore P, et al. Iron overload in patients with chronic viral hepatitis: how common is it? Am J Gastroenterol 1997;92:1298-1301. Tung BY, Emond MJ, Bronner MP, Raaka SD, Cotler SJ, Kowdley KV. Hepatitis C, iron status, and disease severity: relationship with HFE mutations. Gastroenterology 2003;124:318-326....查看详细 (31619字节)
☉ 11325823:Respiratory Syncytial Virus Infection in Elderly and High-Risk Adults
ABSTRACT Background Respiratory syncytial virus (RSV) is an increasingly recognized cause of illness in adults. Data on the epidemiology and clinical effects in community-dwelling elderly persons and high-risk adults can help in assessing the need for vaccine development. Methods During four consecutive winters, we evaluated all respiratory illnesses in prospective cohorts of healthy elderly patients (65 years of age) and high-risk adults (those with chronic heart or lung disease) and in patients hospitalized with acute cardiopulmonary conditions. RSV infection and influenza A were diagnosed on the basis of culture, reverse-transcriptase polymerase chain reaction, and serologic studies. Results A total of 608 healthy elderly patients and 540 high-risk adults were enrolled in prospective surveillance, and 1388 hospitalized patients were enrolled. A total of 2514 illnesses were evaluated. RSV infection was identified in 102 patients in the prospective cohorts and 142 hospitalized patients, and influenza A was diagnosed in 44 patients in the prospective cohorts and 154 hospitalized patients. RSV infection developed annually in 3 to 7 percent of healthy elderly patients and in 4 to 10 percent of high-risk adults. Among healthy elderly patients, RSV infection generated fewer office visits than influenza; however, the use of health care services by high-risk adults was similar in the two groups. In the hospitalized cohort, RSV infection and influenza A resulted in similar lengths of stay, rates of use of intensive care (15 percent and 12 percent, respectively), and mortality (8 percent and 7 percent, respectively). On the basis of the diagnostic codes of the International Classification of Diseases, 9th Revision, Clinical Modification at discharge, RSV infection accounted for 10.6 percent of hospitalizations for pneumonia, 11.4 percent for chronic obstructive pulmonary disease, 5.4 percent for congestive heart failure, and 7.2 percent for asthma. Conclusions RSV infection is an important illness in elderly and high-risk adults, with a disease burden similar to that of nonpandemic influenza A in a population in which the prevalence of vaccination for influenza is high. An effective RSV vaccine may offer benefits for these adults. Respiratory syncytial virus (RSV) was first recognized in 1957 as a cause of bronchiolitis in infants and is the most commonly identified cause of lower respiratory tract infection in young children.1 Mild illness in young adults with reinfection was described and confirmed in subsequent family studies.2,3 However, RSV was not recognized as a potentially serious problem in older adults until the 1970s, when outbreaks of the virus occurred in long-term care facilities.4,5,6,7 Since then, additional studies in hospitalized adults have suggested that RSV may be an important cause of illness in community-dwelling elderly people.8,9 Most previous studies used insensitive viral culture or retrospective serologic studies for diagnosis, a practice that led to widely variable assessments of the incidence and effects of the disease. Recent estimates of the disease burden of RSV in adults have been based on mathematical models linking viral activity in children with hospitalization and death in adults,10,11,12,13,14 and Thompson et al. have estimated that RSV accounts for approximately 10,000 deaths annually in the United States in persons over the age of 65 years.14 Although these estimates are useful, their accuracy is confounded by cocirculation of other respiratory viruses with indistinguishable clinical syndromes and is limited by the assumption that viral activity in infants reflects events in elderly populations.15,16,17 These results have stimulated interest in vaccines and other treatments for RSV in adults.15,18,19 However, additional data regarding virus-specific epidemiology and disease effects, particularly in community-dwelling elderly persons and high-risk adults, are needed before embarking on costly vaccine trials. Therefore, we identified RSV infections during four consecutive winters in prospective cohorts of community-dwelling elderly people and high-risk adults and in persons hospitalized with acute cardiopulmonary conditions. Identical techniques of diagnosing RSV infection and influenza A were used to assess the disease burden and to provide a direct comparison of RSV infection with influenza A, which is a universally recognized cause of serious disease in the populations mentioned above. Methods Study Design The study spanned four consecutive winters, from late 1999 through early 2003 in Rochester, New York. Three groups of patients were recruited: two prospective cohorts (healthy elderly persons and high-risk adults) and a hospitalized cohort of patients who were admitted each winter with cardiopulmonary illnesses. Enrollees or their guardians provided written informed consent. The University of Rochester Research Subjects Review Board and the Rochester General Hospital Clinical Investigation Committee approved the study. Enrollment of Prospective Cohorts Persons who were 65 years of age or older and did not have disabling underlying illnesses (i.e., healthy elderly persons) and persons 21 years of age or older with physician-diagnosed congestive heart failure or chronic pulmonary disease (i.e., high-risk adults) were enrolled in the late summer and fall (from July 15 to November 15) and were followed for a maximum of two winters. To be considered high risk, patients with cardiac disease were required to have at least class II symptoms according to the New York Heart Association's classification, and patients with pulmonary disease were required to have activity-restricting symptoms or use long-term medications.20 Advertisements and mailings were used to recruit patients from health maintenance organizations and from cardiac and pulmonary rehabilitation programs. At enrollment, data on the patients' demographic status, medical history, and functional performance were recorded. Functional status was assessed with the use of a modified Katz Activities of Daily Living (ADL) Scale and the Instrumental Activities of Daily Living (IADL) Scale.21,22 Baseline blood samples were collected from the prospective groups before the RSV season (from July 15 to November 15) and postseason blood samples were collected the following spring (from April 15 to June 15). Illness Evaluation Prospective Cohorts Patients notified study personnel regarding symptoms of respiratory illness or worsening of baseline cardiopulmonary symptoms from November 15 through April 15 of each year. Symptoms included nasal congestion, sore throat, hoarseness, new or worsening cough, sputum production, and dyspnea with or without fever. During home visits, investigators conducted a physical examination, collected nasopharyngeal swabs and blood samples, and obtained a history of the illness. Four to six weeks later, patients were questioned about their functional status and use of health care services (including telephone consultations, office visits, emergency room visits, and hospitalizations). Events related to the use of health care services were recorded as unique if the events were isolated, whereas the highest level of care was counted if the events were directly related. Hospital Cohort During the same surveillance periods, all adults 65 years of age or older or with underlying cardiopulmonary diseases who were admitted to Rochester General Hospital with acute respiratory symptoms were evaluated within 48 hours after admission. Enrollment was performed Monday through Friday, so patients who were admitted on Friday were not eligible. Patients with admission diagnoses of pneumonia (International Classification of Diseases, 9th Revision, Clinical Modification codes 480 to 486), upper respiratory infection (ICD-9-CM code 465), bronchitis (ICD-9-CM code 466), influenza (ICD-9-CM code 487), chronic obstructive pulmonary disease (ICD-9-CM codes 490 to 492 and 496), asthma (ICD-9-CM code 493), viral illness (ICD-9-CM code 79.9), or congestive heart failure (ICD-9-CM code 428) were eligible and underwent identical evaluations as prospective cohorts. Patients' functional activity scores before their illness were determined by a review of records of social workers and nurses plus interviews with patients and their families. Patients were followed until discharge from the hospital. Follow-up visits were made at home or in the hospital four to six weeks after the initial assessment to collect data on functional activity and convalescent-phase blood samples. Laboratory Studies Samples from nasopharyngeal swabs were inoculated into tubes of HEp-2 cells and rhesus monkey kidney cells within four hours after collection, and the remainder were frozen at –80°C. Cultures were examined daily for cytopathic effects in the clinical microbiology laboratory, and viral growth was confirmed by indirect immunofluorescence with the use of monoclonal antibodies specific for RSV and influenzavirus A and B. Reverse-transcriptase polymerase chain reaction (RT-PCR) for RSV and influenza was performed on 250-μl aliquots of samples from nasopharyngeal swabs with the use of single-tube nested reactions with primers from the conserved region of the RSV fusion and influenza A matrix genes.23,24 The limit of detection for each assay was 0.1 plaque-forming unit.25 RSV subgroups A and B were identified by a strain-specific RT-PCR assay.26 Enzyme immunoassay was used to measure serum IgG responses to purified RSV glycoproteins according to established methods.27 The serum IgG responses to influenza A and B antigens were determined with the use of whole-cell lysate assays infected with influenzavirus, as previously described.24,28 An increase by a factor of four or more in the IgG titer in response to any RSV antigen or influenza antigen was considered diagnostic. Definitions of Illness Symptomatic RSV or influenza infections were defined as illnesses with a positive viral culture, a positive RT-PCR assay, or a diagnostic serologic result. Asymptomatic RSV infection was defined as an increase by a factor of four or more in RSV IgG titers in samples obtained after the winter season as compared with those obtained before the winter season in persons without illness or in asymptomatic intervals between illnesses. Interpretation of the serologic results was occasionally complicated by vaccination. During the four years of the study, the timing of influenza vaccination was highly variable because of vaccine shortages or delays. For illnesses that occurred within four weeks after vaccination, the antibody response alone was not sufficient to define influenza infection. Asymptomatic influenza infection was defined as an antibody rise occurring more than four weeks after vaccination during an illness-free interval. Statistical Analysis The chi-square test and Fisher's exact test were used to compare proportions. For data with a normal distribution, means were compared with Student's t-test; for skewed data, the Mann–Whitney test was used. The Poisson regression model and McNemar's test were used to compare the rates of illness and viral infection.29 Results Populations A total of 608 healthy elderly persons and 540 high-risk adults were enrolled in the prospective surveillance. During the same period, 1483 hospitalized patients were eligible for study, of whom 1388 (94 percent) agreed to participate. Demographic characteristics and admission diagnoses were not significantly different for those who declined to participate in the study. Characteristics of the study populations are summarized in Table 1. The average age in each group was at least 70 years. Of the high-risk patients, 73 percent were 65 years of age or older, 17 percent were between the ages of 55 and 64 years, and 10 percent were 54 years of age or younger. The percentage of persons with exposure to children was higher in the high-risk group than in either the healthy elderly group or the hospitalized group (P=0.008), although living situations were similar for the three groups (Table 1). There were significantly lower rates of chronic disease and the use of medication in the healthy elderly cohort than in the high-risk and hospitalized groups. Despite having substantial cardiopulmonary disease, the high-risk group was only slightly less functional than the healthy elderly group. In contrast, the hospitalized group had significantly worse functional scores before hospitalization than did both prospective cohorts (P<0.001). Table 1. Characteristics of the Study Cohorts. Illnesses During the four winter seasons studied, 2514 cases of illness were evaluated (1043 in prospective patients and 1471 in hospitalized patients). Although the numbers of illnesses in the two prospective groups were similar, rates expressed as cases of illness per 100 person-months were higher in high-risk subjects than in healthy elderly patients because of a greater attrition rate (14.3 cases vs. 10.4, P<0.001; relative risk, 1.39; 95 percent confidence interval, 1.23 to 1.57). During the four winters, the activity of both influenzavirus A and B varied considerably, whereas annual RSV activity was relatively constant (Table 2). The circulating influenzavirus strains varied considerably during the years of study.30 The 1999–2000 season was dominated by influenzavirus A H3N2 (99.5 percent) in the mid-Atlantic region. During subsequent years, the circulating strains were as follows: 2000–2001, 37 percent influenzavirus A (97 percent H1N1) and 63 percent influenzavirus B; 2001–2002, 88 percent influenzavirus A (98 percent H3N2) and 12 percent influenzavirus B; 2002–2003, 86 percent influenzavirus A (70 percent H1N1) and 14 percent influenzavirus B. Table 2. Rates of Illness and Infection According to Year of Study. RSV infection was identified in 102 cases of illness involving patients in the prospective cohorts and in 142 cases involving hospitalized patients. Influenza A was diagnosed in 44 cases of illness involving patients in the prospective cohorts and in 154 cases involving hospitalized patients (Table 2). Given the low number of influenza B infections, subsequent discussion will be limited to influenza A and RSV infection. RSV infection developed annually in 3 to 7 percent of the healthy elderly group and in 4 to 10 percent of the high-risk group. There was no significant difference in the rates of RSV infection or influenza A among patients in their first year of surveillance as compared with their second year. Two patients in the prospective cohorts had two cases of RSV infection each, and four patients had influenza A and RSV infection at different times. The number of patients with RSV infection in the prospective cohorts was approximately twice that of patients with influenza A (97 vs. 39, P<0.001). There were 1.5 RSV infections per 100 person-months in the high-risk group and 0.9 in the healthy elderly group (P=0.02; relative risk, 1.61; 95 percent confidence interval, 1.09 to 2.39). Influenza A rates were identical in the two prospective cohorts: 0.5 infection per 100 person-months. Despite higher rates of RSV infection in the prospective cohorts, the overall numbers of patients who had RSV infection and influenza in the hospital cohort were similar. Data on the hospital cohort do not include those for patients from the prospective cohorts who were subsequently admitted to the hospital. Viral Diagnosis Most illnesses (76 percent) were evaluated with all three diagnostic methods (Table 3). Serum from convalescent patients was not available in 18 percent of cases, and nasal specimens were unobtainable in 6 percent. RSV infection was diagnosed with more than one test in 47 percent of cases, RT-PCR alone was used in 20 percent, and serologic testing alone was used in 33 percent. Eleven hospitalized patients had dual infections and were excluded from clinical analyses (nine patients with both RSV infection and influenza A, one with RSV infection and influenza B, and one with influenza A and influenza B). The RSV strain was group A in 73 cases (45 percent) and group B in 89 (55 percent). Both RSV strains circulated each year without significant differences in the percentages of group A and B viruses among mildly ill outpatients and severely ill hospitalized patients. Table 3. Diagnostic Tests. Clinical Effects of Infection in Prospective Cohorts Eighty-nine percent of RSV infections were symptomatic in the prospective cohorts. Five patients in the healthy elderly group and six patients in the high-risk group had serologic evidence of infection without reported illnesses. Similarly, 91 percent of patients with influenza were symptomatic. The symptoms and signs of RSV infection and those of influenza were not substantially different (data not shown). The effects of RSV infection were considerable in both the healthy elderly group and the high-risk group (Table 4). Fifteen percent of patients in the healthy elderly group called their physician and 17 percent made office visits, although none of them required emergency room or inpatient services. The use of medical care was significantly greater in the high-risk group: 23 percent called the doctor, 29 percent made office visits, 9 percent visited the emergency room, and 16 percent required hospitalization. Two high-risk patients with RSV infection (4 percent) died. The mean duration of illness was approximately two weeks in both groups, and 39 percent of patients in the healthy elderly group and 45 percent in the high-risk group were unable to perform the normal activities of daily living for at least one day. The proportion of patients with acute functional impairment was substantially greater in the high-risk group with RSV infection than in the healthy elderly group. Table 4. Infections in Healthy Elderly Patients and High-Risk Patients. Among the healthy elderly patients, influenza A infection generated a greater percentage of office visits than did RSV infection (42 percent vs. 17 percent, P=0.04) and a higher rate of antibiotic use (33 percent vs. 9 percent, P=0.02). Among high-risk patients, the use of medical care was similar in the RSV and influenza A subgroups, although office visits were more common in the influenza A subgroup (60 percent vs. 29 percent, P=0.02). However, because RSV infection occurred more frequently than influenza A, the total number of health care visits (office visits, emergency room visits, and hospitalizations) was similar for the two viruses, at 38 and 30, respectively. Acute functional impairment in the healthy elderly group was also greater with influenza than it was with RSV infection, with 67 percent of patients housebound (P=0.005) and 25 percent confined to bed (P=0.05). None of the patients in the healthy elderly group with influenza were hospitalized or died, whereas 20 percent of high-risk patients were hospitalized. Clinical Effects of Infection with RSV and Influenza A in Hospitalized Patients Demographic and clinical characteristics of patients with RSV infection and patients with influenza requiring hospitalization were not significantly different (Table 5). Twelve percent of patients with RSV infection and 10 percent of patients with influenza were residents of long-term care facilities, a finding that was similar to that of the hospital cohort in general (8 percent). The clinical effects of RSV infection and influenza in the hospitalized cohorts were also similar, as assessed by the length of stay; whether the patient had pneumonia, was in intensive care, or required mechanical ventilation; and mortality. The mortality among patients with RSV infection was higher in the group admitted from long-term care facilities (38 percent) than in the group admitted from the community (3 percent, P<0.001), whereas among patients with influenza, there was no significant difference between the two groups. Five percent of patients with RSV infection and 6 percent of patients with influenza required a higher level of care at discharge than at admission. The mean IADL functional scores increased slightly after hospitalization for patients with RSV infection (4.1±4.1 to 4.9±4.0), and a similar trend was observed among patients with influenza. Overall, according to the diagnosis at discharge, RSV infection accounted for 10.6 percent of hospitalizations for pneumonia, 11.4 percent for chronic obstructive pulmonary disease, 5.4 percent for congestive heart failure, and 7.2 percent for asthma. Table 5. Illnesses in Hospitalized Patients. Discussion This four-year prospective, diagnosis-specific study firmly documents that RSV is an important pathogen in elderly and high-risk adults. Although pediatricians are keenly aware that RSV may cause serious illness in their patients, most internists are less aware of RSV. Given the difficulty with diagnosis in clinical practice and the lack of treatment, this lack of awareness is understandable. However, from a public health perspective, our study shows the substantive disease burden associated with this virus and validates the results of earlier, mathematically derived estimates. Diagnosis by nested RT-PCR allowed a precise determination of the rates of RSV infection that had not previously been possible. In addition, the use of RT-PCR in this study strengthens the causal link between RSV infection and hospitalization, which can be questioned in serologically based studies. In our study, 61 percent of patients who had an increase in antibodies to RSV also had a positive RT-PCR assay, a finding suggesting that infection occurred shortly before admission. Conversely, since 83 percent of patients with a positive PCR assay for RSV whose serum was tested during convalescence had an immune response, it is unlikely that detectable viral RNA reflects transient colonization. The annual incidence of RSV infection in the prospective cohorts averaged 5.5 percent and was relatively constant during the four years and nearly twice that of influenza A. The rate of RSV infection in this study was higher than the 3 percent observed by Nicholson and colleagues in elderly adults in the United Kingdom and probably reflects our use of RT-PCR and a more sensitive serologic test.31 It must be recognized that the rate of influenza was probably reduced by the high rate of vaccination in our population. Since immunization is estimated to have an efficacy of approximately 50 percent for the prevention of respiratory illness in elderly persons, influenza cases might have been expected to double without vaccination.32 Almost all RSV infections were symptomatic, and they frequently led to acute functional impairment and to the use of health care services. One quarter of all healthy elderly patients had contact with a health care provider during their illness; nearly half of all high-risk patients sought medical attention, and 16 percent were hospitalized. Although influenza resulted in greater use of health care services by healthy elderly patients than did RSV infection, differences between RSV infection and influenza were less distinct in the high-risk group, with a similar number of hospitalizations for each type of infection during the four years. However, the effect of the circulating influenza strain was clearly seen. During years 2 and 4, when the dominant strain was H1N1 (one not associated with substantial morbidity and mortality in the elderly), hospitalizations for RSV infection outnumbered those for influenza.14,33 In contrast, when H3N2 influenza was prevalent, in years 1 and 3, admissions for influenza were two to three times as common as those for RSV infection. This finding is consistent with other data indicating that infection with influenza H3N2 but not H1N1 results in a more severe illness than does RSV infection.14 In addition, the high rate of vaccination for influenza in our community probably affected the rate of hospitalization. The efficacy of vaccination in reducing the rate of hospitalization from influenza is estimated to be 40 to 50 percent.34,35 Sixty-eight percent of patients who were hospitalized with influenza reported having been vaccinated, as compared with 75 percent of those with RSV infection, a finding that suggests a more modest vaccine effect. However, even if the number of influenza cases were doubled, rates of hospitalization for RSV and influenza would not be dramatically different. Overall, during the study period, RSV infection accounted for 11 percent of hospitalizations for pneumonia, 11 percent for chronic obstructive pulmonary disease, 5 percent for congestive heart failure, and 7 percent for asthma. According to the National Center for Health Statistics of the Centers for Disease Control and Prevention, in 1999 the numbers of discharges from U.S. hospitals of adults 65 years of age or older for the diagnoses of pneumonia, chronic obstructive pulmonary disease, congestive heart failure, and asthma were 1.3 million, 0.76 million, 2.5 million, and 0.35 million, respectively.36 By applying our rates and adjusting by 50 percent for surveillance during the winter months, RSV infection would account for approximately 177,525 admissions each year. On the basis of our study, which showed that the death rate for hospitalized patients with RSV infection was 8 percent, 14,000 annual deaths would be predicted, a number similar to that estimated by Thompson et al.14 Hospitalization costs alone would exceed $1 billion, an estimate not dissimilar to that made by Han et al.37 Outpatient costs would also probably be substantial given our findings and those of Zambon et al., who reported that up to 18 percent of office visits made by elderly adults for respiratory illnesses during winter were RSV-related.38 In addition to bringing RSV to the attention of internists, our study underscores the continuing importance of yearly influenza epidemics in the expanding elderly and high-risk populations. Programs to improve the efficacy of influenza vaccination and to ensure adequate and timely supplies of vaccine should remain a high priority. However, in order to optimize the reduction in the total burden of viral respiratory disease, we must recognize that other pathogens also contribute to the swell of patients in offices and hospitals during the winter months. The results of this study document the importance of RSV infection in adults and confirm the need for the development of an RSV vaccine for high-risk and elderly adults. Supported by a grant (R01-AI-45969) from the National Institutes of Health. Dr. Falsey reports having received consulting fees from Sanofi–Aventis and GlaxoSmithKline and a grant from Sanofi–Aventis. Dr. Walsh reports having received consulting fees from Sanofi–Aventis, Arrow Therapeutics, and Alnylam Pharmaceuticals. We are indebted to Mary Criddle, R.N., and Anita Gellert, R.N., for evaluations of patients; to Barbara Sikora and Gloria Andolina for technical assistance; to Christine Brower for data management; to the staff and patients at Lifetime Health and Lori Callahan at the Rochester General Hospital Pulmonary Rehabilitation Program for their help in conducting the study; and to Drs. John Treanor and Robert Betts for their thoughtful review of the manuscript. Source Information From the Department of Medicine, Rochester General Hospital (A.R.F., P.A.H., M.A.F., E.E.W.) and the Department of Medicine, University of Rochester School of Medicine and Dentistry (A.R.F., E.E.W.) — both in Rochester, N.Y.; and the Division of Epidemiology, Statistics, and Prevention Research, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Md. (C.C.). Address reprint requests to Dr. Falsey at the Infectious Diseases Unit, Rochester General Hospital, 1425 Portland Ave., Rochester, NY 14621, or at ann.falsey@viahealth.org. References Hall CB. Respiratory syncytial virus and parainfluenza virus. N Engl J Med 2001;344:1917-1928. Hall CB, Geiman JM, Biggar R, Kotok DI, Hogan PM, Douglas RG Jr. Respiratory syncytial virus infections within families. N Engl J Med 1976;294:414-419. Johnson KM, Bloom HH, Mufson MA, Chanock RM. Natural infection of adults by respiratory syncytial virus: possible relation to mild upper respiratory disease. N Engl J Med 1962;267:68-72. Hart RJC. An outbreak of respiratory syncytial virus infection in an old people's home. J Infect 1984;8:259-261. Sorvillo FJ, Huie SF, Strassburg MA, Butsumyo A, Shandera WX, Fannin SL. An outbreak of respiratory syncytial virus pneumonia in a nursing home for the elderly. J Infect 1984;9:252-256. Respiratory syncytial virus infection in the elderly 1976-1982. Br Med J (Clin Res Ed) 1983;287:1618-1619. Vikerfors T, Grandien M, Olcen P. Respiratory syncytial virus infections in adults. Am Rev Respir Dis 1987;136:561-564. Falsey AR, Cunningham CK, Barker WH, et al. Respiratory syncytial virus and influenza A infections in the hospitalized elderly. J Infect Dis 1995;172:389-394. Dowell SF, Anderson LJ, Gary HE Jr, et al. Respiratory syncytial virus is an important cause of community-acquired lower respiratory infection among hospitalized adults. J Infect Dis 1996;174:456-462. Fleming DM, Cross KW. Respiratory syncytial virus or influenza? Lancet 1993;342:1507-1510. Griffin MR, Coffey CS, Neuzil KM, Mitchel EF Jr, Wright PF, Edwards KM. Winter viruses: influenza- and respiratory syncytial virus-related morbidity in chronic lung disease. Arch Intern Med 2002;162:1229-1236. Nicholson KG. Impact of influenza and respiratory syncytial virus on mortality in England and Wales from January 1975 to December 1990. Epidemiol Infect 1996;116:51-63. Neuzil KM, Maynard C, Griffin MR, Heagerty P. Winter respiratory viruses and health care use: a population-based study in the northwest United States. Clin Infect Dis 2003;37:201-207. Thompson WW, Shay DK, Weintraub E, et al. Mortality associated with influenza and respiratory syncytial virus in the United States. JAMA 2003;289:179-186. Morens DM. Influenza-related mortality: considerations for practice and public health. JAMA 2003;289:227-229. McIntosh K, Kapikian AZ, Turner HC, Hartley JW, Parrott RH, Chanock RM. Seroepidemiologic studies of coronavirus infection in adults and children. Am J Epidemiol 1970;91:585-592. Williams JV, Harris PA, Tollefson SJ, et al. Human metapneumovirus and lower respiratory tract disease in otherwise healthy infants and children. N Engl J Med 2004;350:443-450. La Montagne JR. RSV pneumonia, a community-acquired infection in adults. Lancet 1997;349:149-150. Simoes EA. Overlap between respiratory syncytial virus infection and influenza. Lancet 2001;358:1382-1383. Management of chronic heart failure. In: Braunwald E, Zipes DP, Libby P, eds. Heart disease: a textbook of cardiovascular medicine. Philadelphia: W.B. Saunders, 2001:640-1. Lawton MP. The functional assessment of elderly people. J Am Geriatr Soc 1971;19:465-481. Katz S, Ford AB, Moskowitz RW, Jackson BA, Jaffe MW. Studies of illness in the aged: the index of ADL: a standardized measure of biological and psychological function. JAMA 1963;185:914-919. Walsh EE, Falsey AR, Swinburne IA, Formica MA. Reverse transcription polymerase chain reaction (RT-PCR) for diagnosis of respiratory syncytial virus infection in adults: use of a single-tube "hanging droplet" nested PCR. J Med Virol 2001;63:259-263. Walsh EE, Cox C, Falsey AR. Clinical features of influenza A virus infection in older hospitalized persons. J Am Geriatr Soc 2002;50:1498-1503. Falsey AR, Formica MA, Walsh EE. Diagnosis of respiratory syncytial virus infection: comparison of reverse transcription-PCR to viral culture and serology in adults with respiratory illness. J Clin Microbiol 2002;40:817-820. Falsey AR, Formica MA, Treanor JJ, Walsh EE. Comparison of quantitative reverse transcription-PCR to viral culture for assessment of respiratory syncytial virus shedding. J Clin Microbiol 2003;41:4160-4165. Falsey AR, Treanor JJ, Betts RF, Walsh EE. Viral respiratory infections in the institutionalized elderly: clinical and epidemiologic findings. J Am Geriatr Soc 1992;40:115-119. Harmon MW, Kendal AP. Influenza viruses. In: Schmidt NJ, Emmons RW, eds. Diagnostic procedures for viral, rickettsial, and chlamydial infections. 6th ed. Washington, D.C.: American Public Health Association, 1989:631-68. Fleiss JL. Statistical methods for rates and proportions. 2nd ed. New York: John Wiley, 1981:113-6. Centers for Disease Control and Prevention. Influenza season summaries, 1999-2003. (Accessed April 1, 2005, at http://www.cdc.gov/flu/weekly/fluactivity.htm.) Nicholson KG, Kent J, Hammersley V, Cancio E. Acute viral infections of upper respiratory tract in elderly people living in the community: comparative, prospective, population based study of disease burden. BMJ 1997;315:1060-1064. Govaert TME, Thijs CTMCN, Masurel N, Sprenger MJW, Dinant GJ, Knottnerus JA. The efficacy of influenza vaccination in elderly individuals: a randomized double-blind placebo-controlled trial. JAMA 1994;272:1661-1665. Centers for Disease Control and Prevention. Influenza season summary. (Accessed April 1, 2005, at http://www.cdc.gov/flu/weekly/fluactivity.htm.) Nichol KL, Margolis KL, Wuorenma J, Von Sternberg T. The efficacy and cost effectiveness of vaccination against influenza among elderly persons living in the community. N Engl J Med 1994;331:778-784. Foster DA, Talsma A, Furumoto-Dawson A, et al. Influenza vaccine effectiveness in preventing hospitalization for pneumonia in the elderly. Am J Epidemiol 1992;136:296-307. National Center for Health Statistics, Popovic JR. National Hospital Discharge Survey: annual summary with detailed diagnosis and procedure data. Hyattsville, Md.: National Center for Health Statistics, 2001. (DHHS publication no. (PHS) 2001-1722.) Han LL, Alexander JP, Anderson LJ. Respiratory syncytial virus pneumonia among the elderly: an assessment of disease burden. J Infect Dis 1999;179:25-30. Zambon MC, Stockton JD, Clewley JP, Fleming DM. Contribution of influenza and respiratory syncytial virus to community cases of influenza-like illness: an observational study. Lancet 2001;358:1410-1416....查看详细 (34745字节)
☉ 11325824:They Sent Me Here
"Ramonita Ortega," I called out to the crowded waiting room. A slim, 50-ish woman with crisply trimmed gray hair followed me into my office. "They told me to give you this," she said, smiling and shrugging, as she pushed an envelope across the desk toward me. I've always been intrigued by who "they" are — those mystery people referred to with such assumed authority and universality. Particularly in a large city hospital, in which the staff is mammoth and constantly changing, "they" constitute a particularly encompassing force. I glanced at her chart before opening the envelope. Ms. Ortega had no medical history, except for a three-pack-a-day smoking habit she'd given up several years ago. She had gone to the dermatology clinic recently for the removal of a sebaceous cyst on her back. The cyst was not healing well, so she was headed toward ambulatory surgery for a more formal excision. She had been to presurgical testing, and I assumed that she had been sent to the medical clinic for a routine pre-op evaluation. The envelope was unsealed, and Ms. Ortega watched, slightly bemused, as I fumbled with the papers to extricate them. On top was a handwritten consult sheet from the presurgical-testing clinic. "Please eval for LUL mass," was scrawled on top; the rest of the page was blank. LUL mass? An icy edge sliced through the air and I blinked twice, not entirely sure that I had read correctly. A mass in the left upper lobe of the lung? The "routine visit" atmosphere was suddenly annihilated by the specter of cancer, and the pleasantries of a getting-to-know-you meeting dissipated with austere efficiency. I looked up from the page and caught Ms. Ortega's eyes. They were an unsullied brown, with only a scattering of wrinkles gracing their edges. I withdrew my gaze quickly, self-consciously. It was clear that Ms. Ortega and I were now intimates in a different realm. We now shared an awful knowledge and the grim resignation that went with it. I couldn't bear to hold her gaze in mine. I turned to the attached x-ray report. "Indication: routine pre-op in an otherwise healthy female. Results: left upper lobe ovoid mass visualized, along with several satellite lesions. Suspicious for malignancy." "Damn," I whispered to myself, laying the papers down and unconsciously pushing them into the general mess on my desk. I forced myself to look up at this healthy-appearing woman, but all I could see was the path of CT scans, biopsies, chemotherapy, living wills, morphine drips, hospice. I shut my eyes again, but the vision remained: the beginning of a grisly journey. The path was cut, and we were already several steps along it. I opened my eyes, dreading the necessity to begin but grateful that at least that first horrible hurdle — the actual telling of the bad news — was already past, and there were some practical tasks ahead of us, concrete items that were easier to focus on. "Well," I said, swallowing, trying to sound as matter-of-fact as possible. "Well, we'll just start with a CT scan; that'll help us get a better look at that lung mass. Radiology is on the third floor," I continued, reaching, almost too quickly, for the form in my drawer. My fingers jittered as I filled in the blanks. "Have you ever had allergies to contrast dye in CT scans?" I asked. Ms. Ortega hadn't moved in her chair since I'd started speaking. Her smile from my earlier clumsiness was still there, though it had pulled inward slightly. I imagined that this chilling reminder of the reason for her visit with me was sinking in, clouding over the nice rapport that we'd been establishing. I wanted to respect this difficult moment, so I completed the CT form in silence. Finally, she spoke. "Lung mass?" she said slowly. "What . . . ," she paused, "are you talking about?" The pen clattered as it dropped from my hand. There was an agonizing blankness as I stared dumbly at her. "Didn't they . . ." I was unable to unlock my eyes from hers. I groped for the x-ray report I'd pushed aside, suddenly desperate to retrieve the "evidence." "Didn't they . . . tell you?" "No," Ms. Ortega said, in a voice that seemed far too calm, blinking as if to clear her vision. "I came back for my results and they just handed me an envelope. They said I should give it to you." Her eyes searched my face, and her cadence and tone softened to one more of surprise than hurt. "They just said that my surgery was canceled." I finally located the x-ray report and clamped my sweaty fingers around it. "Left upper lobe ovoid mass," the black letters reiterated. They had to have told her about it when they canceled her surgery. They had to have told her about it when they sent her to the medical clinic. How could they not? I could feel my anger rising like bitter bile. The innocence of Ms. Ortega's surprise both pained and perplexed me. I wondered why she hadn't peeked into the unsealed envelope to read the information she had been instructed to ferry to me. She was so trusting of "them" that she didn't stop to question. I watched Ms. Ortega's face, waiting for it to contort into anger, indignation, at least annoyance. But it didn't. The faintly raised eyebrows, the lips half-parted, suspended in what might have been mid-word, suggested surprise and bewilderment. Her poise — perhaps it was shock — lent an eerie calm to the room. I, on the other hand, was furious at "them." How could they have done this to Ms. Ortega? And how could they have put me in this position — of talking to a patient with the mundane familiarity of comrades in disease, only to run slipshod over one of the most vulnerable moments in medicine? I imagined a faceless "they" scrolling through the pre-op lab results in the computer, stumbling onto the x-ray report. I wondered whether there was a catch in their breath when they saw the report. Did they avert their gaze when they told Ms. Ortega that her surgery had been canceled and that she needed to see a new doctor? Did they fumble for an explanation as they spoke to her, something benign enough so she wouldn't get scared but urgent enough so she would keep the appointment? Did they notice a raw pinch in their stomach as they slid the x-ray report into the envelope for her? Or did they simply leave the envelope at the front desk for her to pick up? Didn't they bear some responsibility, as the first physicians to have laid eyes on the x-ray report? But "they" were a mysterious and anonymous gray zone. They'd made the appropriate referral to an internist but had slunk away from the messier part. "Ms. Ortega . . ." I reached across the desk and slid my hand over hers. "The x-ray of your chest shows a mass." Ms. Ortega's brown eyes remained fixed on mine. "I can't tell you for sure what this mass is, but cancer is a strong possibility." No medical history, except for a three-pack-a-day smoking habit she'd given up several years ago. I felt the warmth of her hand calm mine. "Whatever this mass is, we need to find out as soon as possible." Ms. Ortega's face relaxed. It settled into an odd, slight smile. "I'm with you on that one, doctor. Whatever God has in store for me, I want to know." I held onto her hand, waiting — again — for shock, anger. But it didn't come. Did she not put two and two together and realize that the previous doctors had withheld this news? Or did the anvil edge of a possible cancer diagnosis overshadow this issue that I seemed so fixated on? Perhaps she was used to an anonymous "they" in her life and simply wasn't perturbed by it. For the remainder of our visit, Ms. Ortega remained reserved, focused on the tasks at hand. I asked several times if she had any questions or concerns, but she shook her head. Her main worry was that she would have to miss another day of work in order to have the CT scan. All I could think of was that soon enough she wouldn't be able to work at all. But I couldn't say that. I couldn't tell her that I was 99 percent convinced that it was cancer, most likely metastatic. Not, at least, until I had a biopsy result. But that wouldn't stop me from making an oncology appointment for her. I suddenly wondered whether I was acting like "them": withholding some information, making referrals to specialists. I rationalized that I had been honest about the possibility of cancer and that there was no way to say for sure until the biopsy. But still, I knew. I knew. And I didn't share my certainty with her. The visit ended, unsettlingly, on the same even keel on which it had started. Our rapport was smooth, the treatment plan clear, the ends neatly — bizarrely — tied up. I found myself trembling from the incongruity of it, my rage at "them" threatening to spill over. They had been in possession of the information; how could they not have told her? I showed Ms. Ortega to the door, shook her hand, wished her well. I wanted to apologize on behalf of "them," on behalf of us, on behalf of the controlling forces of the universe, for the ineptitude we had shown her so far and for the unfairness of being selected for this disease. I wanted to promise that henceforth she would be treated with perfect sensitivity and that we would eradicate her disease. But I couldn't predict how the next set of doctors would behave, and, of course, I couldn't alter the unforgiving dictates of tumor biology. Mostly, though, I wanted her to be angry, to share my rage. As our hands slipped from their grasp, I realized that I was being selfish. My anger was my issue — not hers, if she didn't want it to be. Ramonita Ortega was entitled to her own interpretations, her own defenses, and her own rhythm of striding forth in the world. Perhaps her priorities were, understandably, elsewhere right now. Who was I to impose? But when the door closed, I seethed. (Identifying details have been changed to protect the patient's privacy.) Source Information Dr. Ofri is an assistant professor of medicine at New York University School of Medicine and editor-in-chief of the Bellevue Literary Review. An interview with Dr. Ofri can be heard at www.nejm.org....查看详细 (10305字节)
☉ 11325825:A Unifying Mutation in Chronic Myeloproliferative Disorders
In 1892, Louis Vaquez of Paris described a patient with cyanotic polycythemia; the autopsy disclosed massive enlargement of the spleen and liver. In 1903, William Osler, then at Johns Hopkins Hospital, reported on four patients with polycythemia, two of whom had splenomegaly. He gave credit to Vaquez for the earlier description, and the disorder was later named Osler–Vaquez disease, though today it is usually referred to as polycythemia vera. In 1951, William Dameshek drew attention to the relationships among polycythemia vera, idiopathic myelofibrosis, and essential thrombocythemia and proposed that these diseases, as well as chronic myeloid leukemia and erythroleukemia, should be grouped together in the general category of myeloproliferative syndromes. This proposal may have been regarded as suspect at the time, but this year it seems to have been fully vindicated by four research groups that independently discovered that most patients with polycythemia vera and some with myelofibrosis and essential thrombocythemia have an identical acquired point mutation in the Janus kinase 2 (JAK2) gene. The four members of the Janus kinase (JAK) family, Janus kinases 1, 2, and 3 and tyrosine kinase 2 (JAK1, JAK2, JAK3, and TYK2), have slightly different functions.1 Each has a kinase domain (JAK homology 1, or JH1) and a catalytically inactive pseudokinase domain with an important regulatory function (JAK homology 2, or JH2). To some, the presence of these two similar domains in the protein, one active and the other inactive, was reminiscent of the Roman god Janus, who looked simultaneously in two directions — hence the name. The JAK proteins function as intermediates between membrane receptors and signaling molecules. When particular cytokines or growth factors bind to their receptors on the cell surface, JAK proteins, which are kinases associated with the cytoplasmic regions of these receptors, become phosphorylated and thereby activated. This activation creates docking sites for downstream molecules, notably those of the STAT (signal transducer and activator of transcription) family (see diagram, Panel A). Activated STAT molecules enter the nucleus, where they act as transcription factors. JAK2 seems to be activated particularly when receptors bind to hematopoietic growth factors. Mutations in the drosophila homologue of the human JAK2 gene are known to cause a leukemia-like phenotype in affected flies, and rare cases of leukemia in humans are associated with TEL–JAK2 fusion genes. Involvement of Janus Kinases in Cytokine Signal Transduction (Panel A)and Structural Map of Janus Kinase 2 (Panel B). On ligand binding by receptors (Panel A), Janus kinase (JAK) proteins make contact with the cytoplasmic domain of the receptor, where they catalyze the phosphorylation of tyrosines. This action, in turn, recruits STAT (signal transducer and activator of transcription) molecules, which are phosphorylated on their SRC homology 2 (SH2) domains, dimerize, and translocate to the nucleus, where they act as transcription factors. The JAK homology 1 (JH1) domain (Panel B) is the active kinase domain of JAK2, and the JAK homology 2 (JH2) domain is a pseudokinase with autoinhibitory properties. JAK2 also carries a band 4.1(f)-ezrin-radixin-moesin (FERM) domain. P indicates a site of autophosphorylation. The position of the mutated V617F codon is indicated by the arrow. In this issue of the Journal, Kralovics and colleagues in Basel, Switzerland, and Pavia, Italy (pages 1779–1790), report that 83 of 128 patients with polycythemia vera (65 percent) had a guanine-to-thymine mutation encoding a valine-to-phenylalanine substitution at position 617 (V617F) in the JH2, or autoinhibitory, domain of JAK2 (see diagram, Panel B). They found the same mutation in 57 percent of patients with myelofibrosis and in 23 percent of patients with essential thrombocythemia. The mutation was found only in hematopoietic cells and must therefore be an acquired somatic mutation. Normally, one would say that such consistent findings still required independent confirmation, but such confirmation is already available from both sides of the Atlantic. A research group in Paris2 reported the same mutation in 40 of 45 patients with polycythemia vera and a minority of patients with myelofibrosis and essential thrombocythemia. A Boston group3 has reported that 121 of 164 patients with polycythemia vera had the V617F mutation in their granulocytes, as did 37 of 115 patients with essential thrombocythemia and 16 of 46 patients with myelofibrosis. And a group in Cambridge, United Kingdom,4 found the V617F mutation in 71 of 73 patients with polycythemia vera, 29 of 51 patients with essential thrombocythemia, and 8 of 16 patients with myelofibrosis. Though the proportions of patients with the mutation vary somewhat in the different series, there can be little doubt that the observation is real and likely to be of major importance. Although these four articles all appeared within a period of just six weeks, the logic and preceding experimental work were essentially different in each case. The Swiss–Italian study was based on the prior observation that a minority of patients with polycythemia vera had a loss of heterozygosity in a restricted region of chromosome 9p that included the site of the JAK2 gene, and this led to a search for mutations in JAK2. The French study followed from the observation that the formation in vitro of the endogenous erythroid colonies that are characteristic of polycythemia vera could be inhibited by small molecules that block the action of JAK2. The Boston group, stimulated by the known involvement of activated tyrosine kinases in chronic myeloid leukemia, chronic myelomonocytic leukemia, and the hypereosinophilic syndrome, undertook a high-throughput DNA sequence analysis of the activation loops and autoinhibitory domains of 85 tyrosine kinases. The Cambridge group focused on the key role of JAK2 in signal transduction from multiple hematopoietic growth factor receptors and thus selected it as an attractive candidate for further study. The remarkable finding of the V617F mutation by four independent research groups raises as many questions as it answers. How, for example, does this mutation contribute to the pathogenesis of these myeloproliferative disorders? It seems likely that it disrupts the JH2 inhibitory regulation of JAK2, leaving the enzyme constitutively active. The activated kinase may then bind to a receptor and recruit STATs in the total absence of hematopoietic growth factor or in the presence of only trace quantities of the factor. Such a mechanism fits nicely with the observation by the Cambridge group that all patients with polycythemia vera who had the mutation had cells in their blood that formed erythroid colonies in vitro in the absence of erythropoietin.4 The net result could be chronic low-grade but excessive stimulation of erythropoiesis, a characteristic of polycythemia vera. Why are some patients with polycythemia vera heterozygous and others homozygous for the mutation? The evidence suggests that homozygosity for the mutant gene results from the mitotic recombination of chromatids bearing the mutation and not from a second mutation in a mutant heterozygous lineage. Either way, the homozygosity may be the result of two distinct steps, the first of which is enough to produce features of the disease. And what of the patients with polycythemia vera, essential thrombocythemia, or myelofibrosis who apparently do not have JAK2 mutations? Can we expect to find another unifying mutation equivalent to this one? If so, will it be in the JAK–STAT pathway or independent of it? Even if Dameshek was right to link these myeloproliferative disorders, how exactly could the same acquired mutation in the JAK2 gene cause three clinical entities that are more or less distinct? The simplest explanation is merely to postulate the existence of other genetic abnormalities that either are preexisting or occur after the acquisition of the JAK2 mutation. Other possibilities must also exist. And what is the basis for the progression from a seemingly benign condition (polycythemia vera) to acute leukemia in some, but not all, cases? The question brings to mind the analogy with chronic myeloid leukemia, a disease associated with an activated tyrosine kinase, which also starts gently and progresses to an aggressive termination. Extending the analogy, one may speculate that a small molecule that inhibits normal and mutant JAK2 could prove clinically useful in these myeloproliferative disorders, as it has so impressively in chronic myelogenous leukemia. At the very least, this newly identified molecular lesion will form the basis of a new classification. But it seems likely that patients will also eventually derive substantial benefit from the discovery. Source Information Dr. Goldman is a Fogarty Scholar in the Hematology Branch of the National Heart, Lung, and Blood Institute, Bethesda, Md. References Yamaoka K, Saharinen P, Pesu M, Holt VE III, Silvennoinen O, O'Shea JJ. The Janus kinases (Jaks). Genome Biol 2004;5:253-253. James C, Ugo V, Le Couedic J-P, et al. A unique clonal JAK2 mutation leading to constitutive signalling causes polycythaemia vera. Nature (in press). Levine RL, Wadleigh M, Cools J, et al. Activating mutation in the tyrosine kinase JAK2 in polycythemia vera, essential thrombocythemia, and myeloid metaplasia with myelofibrosis. Cancer Cell (in press). Baxter EJ, Scott LM, Campbell PJ, et al. Acquired mutation of the tyrosine kinase JAK2 in human myeloproliferative disorders. Lancet 2005;365:1054-1061....查看详细 (9771字节)
☉ 11325826:Orchestration of Iron Homeostasis
The number of newly identified genes participating in the regulation of iron homeostasis has increased at a remarkable pace. The characterization of these genes has led investigators to challenge previous models of the regulation of iron homeostasis in health and its dysregulation in disease. There is now substantial evidence that the liver plays a central role in determining how much iron is absorbed from the gut and in influencing the release of iron from sites of storage. The discovery of the iron regulatory hormone hepcidin has provided a cohesive theory to explain the pathophysiology of such common disorders as hereditary hemochromatosis and the anemia of inflammation (also known as the anemia of chronic disease). The most important cellular targets for hepcidin appear to be the villus enterocyte, the reticuloendothelial macrophage, and the hepatocyte (see diagram). Interplay of Key Proteins in Iron Homeostasis. In the duodenal enterocyte, dietary iron is reduced to the ferrous state by duodenal ferric reductase (Dcytb), transported into the cell by divalent metal transporter 1 (DMT1), and released by way of ferroportin into the circulation. Hephaestin facilitates enterocyte iron release. Hepatocytes take up iron from the circulation either as free iron or transferrin-bound iron (through transferrin receptor 1 and transferrin receptor 2). Transferrin receptor 2 may serve as a sensor of circulating transferrin-bound iron, thereby influencing expression of the iron regulatory hormone hepcidin. The hepcidin response is also modulated by HFE and hemojuvelin. Hepcidin is secreted into the circulation, where it down-regulates the ferroportin-mediated release of iron from enterocytes, macrophages, and hepatocytes (dashed red lines). There are no substantial physiologic mechanisms that regulate iron loss. Accordingly, iron homeostasis is dependent on regulatory feedback between body iron needs and intestinal iron absorption. Several factors have been found to influence the rate of iron absorption, including the body's iron stores, the level of erythropoietic activity in bone marrow, the blood hemoglobin concentration, the blood oxygen content, and the presence or absence of inflammatory cytokines.1 More than one of these factors may act simultaneously, and some are interrelated. Intestinal iron absorption increases with decreased iron stores, increased erythropoietic activity, anemia, or hypoxemia. Conversely, intestinal iron absorption decreases in the presence of inflammation — a process that contributes to the anemia of inflammation. Excess iron absorption relative to body iron stores is the hallmark of hereditary hemochromatosis.2 Nearly all absorption of dietary iron occurs in the duodenum. Several steps are involved, including the reduction of iron to a ferrous state, apical uptake, intracellular storage or transcellular trafficking, and basolateral release. Molecular participants in each of these processes have been identified3 (see diagram). The reduction of iron from the ferric to the ferrous state occurs at the enterocyte brush border by means of a duodenal ferric reductase (Dcytb). Ferrous iron is then transported across the apical plasma membrane of the enterocyte by divalent metal transporter 1 (DMT1). Iron taken up by the enterocyte may be stored intracellularly as ferritin (and excreted in the feces when the senescent enterocyte is sloughed) or transferred across the basolateral membrane to the plasma. This iron is transferred out of the enterocyte by the basolateral transporter ferroportin — a process that is facilitated by the ferroxidase activity of the ceruloplasmin homologue hephaestin. The expression of each of the genes involved in these steps is subject to regulation. Changes in the expression of each of the identified molecules that participate in iron absorption have been examined in various conditions. The best characterized of these conditions is anemia caused by dietary iron deficiency, in which the up-regulation of duodenal DMT1, Dcytb, and ferroportin messenger RNA and protein is observed. Iron released into the circulation binds to transferrin and is transported to sites of use and storage. Production of hemoglobin by the erythron accounts for most iron use. High-level expression of transferrin receptor 1 in erythroid precursors ensures the uptake of iron into this compartment. Hemoglobin iron has substantial turnover, as senescent erythrocytes undergo phagocytosis by reticuloendothelial macrophages. Iron export from macrophages is accomplished primarily by ferroportin, the same iron-export protein expressed in the duodenal enterocyte. Hepatocytes serve as a storage reservoir for iron, taking up dietary iron from portal blood and, at times of increased demand, releasing iron into the circulation by way of ferroportin. The ferroportin-mediated release of iron from enterocytes, macrophages, and hepatocytes is recognized as an important determinant of iron homeostasis. The discovery of hepcidin revealed the important role of the hepatocyte in sensing the body iron status and modulating the ferroportin-mediated release of cellular iron. Hepcidin is a 25-amino-acid peptide that was first identified in urine and plasma during a search for novel antimicrobial peptides.4 However, its role in influencing the systemic iron status has been discovered to be paramount, and hepcidin is now considered to be the principal hormone involved in iron regulation. Each of the previously mentioned factors regulating intestinal iron absorption (iron stores, erythropoietic activity, hemoglobin, oxygen content, and inflammation) also regulates the expression of hepcidin by the liver. When each of these factors undergoes a change, intestinal iron absorption varies inversely with liver hepcidin expression. Hepcidin decreases the functional activity of ferroportin by directly binding to it and causing it to be internalized from the cell surface and degraded.5 In the enterocyte, this action would be expected to decrease basolateral iron transfer and thus dietary iron absorption. In the reticuloendothelial macrophage and the hepatocyte, hepcidin would lead to a decrease in iron export and thus an increase in stored iron. Abnormalities in hepcidin regulation have now been implicated in two important clinical conditions: hereditary hemochromatosis and the anemia of inflammation. The abnormalities of iron homeostasis seen in hereditary hemochromatosis are the converse of those seen in the anemia of inflammation. Hepcidin expression is inappropriately low in patients with the former condition, whereas it is increased in patients with inflammatory conditions. In hereditary hemochromatosis, there is increased dietary iron absorption, relative sparing of iron in reticuloendothelial macrophages, and increased iron saturation of circulating transferrin. Hepatocytes become iron-loaded in this setting, presumably because the uptake of iron from the circulation exceeds their ferroportin-mediated iron export. Conversely, in the anemia of inflammation, iron retention by duodenal enterocytes and reticuloendothelial macrophages leads to markedly low transferrin saturation, iron-restricted erythropoiesis, and mild-to-moderate anemia. Thus, hepcidin offers a unifying explanation for the abnormalities in iron metabolism observed in these two common clinical conditions. Most patients with hereditary hemochromatosis are homozygous for the C282Y mutation in the HFE gene. In this issue of the Journal, Adams et al. (pages 1769–1778) report the results of a large population screening study examining the prevalence and consequences of the C282Y mutation in various racial and ethnic groups. The authors found that although most persons who are homozygous for this mutation have elevations of the mean ferritin level and transferrin saturation, individual variability is great. Moreover, the differences observed among racial and ethnic groups in these iron-related variables could not be accounted for by differences in the HFE genotype. These data indicate that although the HFE mutation is the most important heritable cause of iron overload, basal iron status is significantly influenced by other genetic factors, environmental factors, or both. The contribution of genetic factors is probably substantial, as suggested by data from strains of inbred mice. Genes other than HFE have been identified that, when mutated, lead to decreased hepcidin expression and clinical hereditary hemochromatosis. One of these genes (TFR2) encodes transferrin receptor 2, a homologue of the classic transferrin receptor that is highly expressed by hepatocytes. It has been postulated that transferrin receptor 2 may act as a "sensor" of circulating iron and thereby influence hepcidin expression. Another such gene is hemojuvelin (HJV), which is mutated in most persons with juvenile hereditary hemochromatosis. These observations suggest that HFE, TFR2, and HJV participate in a pathway that regulates hepcidin expression. Polymorphisms in these genes might contribute to the observed variation in basal iron status. Although much has been learned regarding the regulation of iron homeostasis, many important questions remain. The molecular mechanisms by which HFE, TFR2, and HJV influence hepcidin expression are unknown. HFE expression in cell types other than hepatocytes (e.g., reticuloendothelial cells or duodenal crypt cells) may also influence iron homeostasis. Moreover, additional gene products involved in iron metabolism — for instance, the dietary heme transporter and proteins that participate in intracellular iron trafficking — have yet to be identified. There may be therapeutic potential for hepcidin antagonists in the treatment of the anemia of inflammation, or for exogenous hepcidin in the treatment of hemochromatosis. Investigations focused on these unanswered questions will continue to expand our understanding of how iron absorption and distribution are regulated in health and dysregulated in certain diseases. Source Information Dr. Fleming is an associate professor of pediatrics and biochemistry and molecular biology and Dr. Bacon a professor of internal medicine at the Saint Louis University School of Medicine, St. Louis. References Miret S, Simpson RJ, McKie AT. Physiology and molecular biology of dietary iron absorption. Annu Rev Nutr 2003;23:283-301. Pietrangelo A. Hereditary hemochromatosis -- a new look at an old disease. N Engl J Med 2004;350:2383-2397. Hentze MW, Muckenthaler MU, Andrews NC. Balancing acts: molecular control of mammalian iron metabolism. Cell 2004;117:285-297. Ganz T. Hepcidin, a key regulator of iron metabolism and mediator of anemia of inflammation. Blood 2003;102:783-788. Nemeth E, Tuttle MS, Powelson J, et al. Hepcidin regulates cellular iron efflux by binding to ferroportin and inducing its internalization. Science 2004;306:2090-2093....查看详细 (11024字节)
☉ 11325827:Medicine and Compassion: A Tibetan Lama's Guidance for Caregivers
Especially since the 14th Dalai Lama received the Nobel Peace Prize in 1989, the Tibetan tradition has gained center stage in the West. This book is a simple and well-written introduction to the Tibetan variant of Buddhism, a global religion that has garnered increasing interest in the United States since Zen textbooks became available in the 1950s. In folksy English, the book explains the basics of the belief system, including the concepts of impermanence, attachment, suffering, and "emptiness suffused with compassion." Emphasizing that the Buddhist idea of "empty mind" and compassion are essentially innate and indistinguishable, the book offers simple meditation practices and visualizations (mostly having to do with concentrating on breathing) as a direct way to cultivate "nonconceptual compassion." Even though the book does not specifically target health care providers (meditation and compassion seem to be good for everyone), there are plenty of insights that will be worthwhile for caregivers. We are told that even if we are saddened because we cannot cure everyone, we can find some joy if we make our effort to help 100 percent. We are told that treatment includes gestures and nonverbal communication of reassurance, caring, calmness, and help in removing fear. We are asked to remember that we are all "waiting in line to die." Medicine and Compassion is most interesting when it touches on Tibet's unique cultural traditions. For example, it provides a dramatic glimpse into another conceptual world in its descriptions of the process of dying, during which, according to Tibetan beliefs, the spirit moves through various bardo realms, where mind-consciousness is reincarnated. Originally developed as a radical rejection of Hinduism 2500 years ago, Buddhism has always had an intense and rigorous dialogue with other religions on such issues as non-self, non-theism, and immanence. Unfortunately, this dialogue has not often taken place in the West, where Buddhism often finds itself in the environs of New Age spiritual consumerism. Although the book's introduction claims that "this is not New Age stuff," the book merges into New Age unrestrained "dispensations" as it emphasizes Buddhism as a religion of unlimited abundance that accesses the unrestricted Buddha within. This Westernized Buddhism has little to do with demand, limitation, obligation, and responsibility. Reaching enlightenment — the arduous effort of making no effort — is watered down to being unafraid to take a "vacation" from our hectic lives with 15 minutes of daily meditation while working toward "relaxation" (a word rarely found in any Buddhist canon). Buddhism becomes indistinguishable from what, in 1902, William James called the emerging American "Gospel of Relaxation." The weakness of this book is most evident in its discussion of Tibetan medicine itself. In fact, recognizable Tibetan medicine is not 2500 years old, as the book claims. Rather, Tibetan medicine is an amalgam of Ayurvedic, Chinese, and Hippocratic thought, synthesized with indigenous shamanism in a series of conferences inaugurated during the consolidation of the Tibetan Empire between 634 and 755 A.D. This broad-minded acceptance of diverse traditions is a rare historical example of active medical pluralism. Scholars accept that translations of some Hippocratic texts are embedded in canonical Tibetan medical books. In reading Medicine and Compassion, one easily recognizes ideas from Hippocrates's On Decorum, which states that the physician should "bear in mind his manner of sitting, [maintain] . . . decisive utterance, brevity of speech, composure, diligence, care, replies to objections, calm self-control, concentration, readiness to do what has to be done. . . . Perform all this calmly." In a curious way, the journey to the East in this book brings the reader back to Western medicine's point of departure. Medicine and Compassion is a delightful book, but for accounts that are more intellectually challenging, I would recommend Edward Conze's classic Buddhism (1951); for Tibetan Buddhism, Ch?gyam Trungpa's Cutting through Spiritual Materialism (1974); and for Buddhist health care perspectives, Lawrence Sullivan's Healing and Restoring (1989). Ted J. Kaptchuk Harvard Medical School Boston, MA 02215...查看详细 (4348字节)
☉ 11325828:Wider Than the Sky: The Phenomenal Gift of Consciousness
"Consciousness is the guarantor of all we hold to be human and precious. Its permanent loss is considered equivalent to death, even if the body persists in its vital signs." It is with this allusion to the permanent vegetative state that Gerald Edelman opens his latest book, Wider Than the Sky. Edelman aims to answer the question of how the firing of our neurons gives rise to conscious, subjective experiences — or, as philosophers call it, "qualia." He hopes "to disenthrall those who believe the subject is exclusively metaphysical or necessarily mysterious." The title of the book comes from a poem by Emily Dickinson: "The Brain — is wider than the Sky — / For — put them side by side — / The one the other will contain" (circa 1862). Having laid the groundwork in his critically acclaimed books Neural Darwinism (1987), Topobiology (1988), Remembered Present (1990), Bright Air, Brilliant Fire (1992), and A Universe of Consciousness (2000, written with Giulio Tononi), Edelman here elegantly summarizes his thinking on consciousness. This is, as he calls it himself, a small book, but reading it requires a concentrated effort. Edelman sees his work as a completion of Charles Darwin's in the sense that he views consciousness as a product of evolution, and he cites the idea from Darwin's notebook (1838) that "he who understands baboon will do more toward metaphysics than Locke." Edelman emphasizes that a brain-based explanation of consciousness cannot and need not offer an "explanation that replicates or creates any particular conscious experience," in the same way that a theory that explains how a hurricane arises cannot create the experience of a hurricane or even get one wet "by description." For Edelman, a biologic theory of consciousness must rest on a global theory of the brain (a reference to Bernard Baars's Global Workspace Theory) and must strictly obey the principles of physics: "no spooky forces that contravene thermodynamics." He makes the distinction between primary and higher-order consciousness. Primary consciousness relates to being mentally aware of a scene, in what Edelman has coined the "remembered present" (a reference to William James's "specious present"). This could be compared to the form of consciousness associated with rapid-eye-movement sleep. Primary consciousness would have evolved as our species did (it remains unclear when), because it increased the chances of survival. According to Edelman, animals with primary consciousness experience qualia but are not conscious of being conscious. Only humans and, "to some minimal degree," higher primates would have a higher-order consciousness that permits them to have a social concept of the self and concepts of the past and the future. Higher consciousness in its most developed form, Edelman thinks, requires the acquisition of language. Edelman, who won the Nobel Prize in Physiology or Medicine in 1972 for his studies on the structure and diversity of antibodies (which established that the immune system works according to Darwinian principles), once again applies the theory of natural selection to his own theory of neuronal group selection, which he first proposed in 1978. Key to this hypothesis is the proposal that "reentry" is a central organizing principle that governs the functioning of our brains: the dynamic recursive signaling ("reentry") within the thalamocortical system (the "dynamic core") would give rise to our conscious perceptions. These core states change within hundreds of milliseconds as different circuits are activated by stimuli within our environment, our bodies, and our brains. Only some of these states are stable and thus become integrated, giving rise to the unitary property of consciousness. Similarly, memory is considered nonrepresentational and necessarily associative as a result of the interactions among massively degenerate networks. Edelman thinks that computer or machine models of consciousness will not work and that much of cognitive psychology is ill founded, since there are no functional states that can be uniquely equated with defined or coded computational states in individual brains and no processes that can be equated with the execution of algorithms. "A genuine glimpse into what consciousness is would be the scientific achievement, before which all past achievements would pale. But at present, psychology is in the condition of physics before Galileo," wrote William James in 1899. Edelman's hypotheses, even if they are still far from solving all of the detailed mechanistic problems related to the local operations of networks in the brain, give us such a glimpse. Together with the writings of other pioneers such as Francis Crick, this book has the great merit of offering testable hypotheses to the ever-increasing number of "consciousnologists." Steven Laureys, M.D., Ph.D. Université de Liege 4000 Liege, Belgium steven.laureys@ulg.ac.be...查看详细 (4972字节)
☉ 11325829:Late-Life Depression
This book is "state of the art," an observation that is both a compliment and a caution. The editors have brought together many of the leading researchers in the field to assemble an authoritative reference that will be useful for students, residents, practicing physicians, and mental health professionals in related fields. For a multiauthored textbook, Late-Life Depression is well organized, appropriately succinct, and clear. Those qualities in themselves are accomplishments. An Artist's Interpretation of a Person with Depression. Nanette Hoogslag/Wellcome Photo Library. The great strength of the book is its medical and biologic orientation. Indeed, it might have been more specifically titled Medical and Biologic Perspectives of Late-Life Depression. It will serve as an excellent resource for those seeking to understand the clinical varieties of the condition, relevant pathobiologic theories and correlates, and approaches to treatment. With the exception of one chapter, entitled "Psychotherapy in Old-Age Depression," however, the therapies that are discussed are solely biologically driven — both pharmacologic and electroconvulsive. It is ironic that the book's medical and biologic orientation is also its great weakness. Reading it, I might have thought that psychological and socially oriented theories of depression in later life had disappeared altogether. Although the book's contributors give deep obeisance to the "vascular hypothesis," or neuroendocrinologic and neuroanatomical correlates of depression, it is mystifying to me that they omit comparable consideration of developmental psychology, late-life social and functional changes and losses, and the potential role of vulnerabilities of personality in the genesis of depressive conditions. An argument could certainly be made that the supporting data for such perspectives are just as robust (or as weak) as those presented here. There are other important gaps in the book. Although there is an important introductory chapter on the epidemiology and treatment of depression in residential care settings, virtually nothing is said about the challenges of treating depressed elderly patients in primary care venues. That is where most of the action takes place, not in psychiatrists' offices or on any inpatient psychiatric service. Physicians who are treating depressed elderly persons often work as much with family members as with the patients themselves, but I could find no mention of this reality in the book. Except for a relatively brief mention of approaches to suicide prevention, there is nothing of what I call "public health and preventive psychiatry," a perspective that invites consideration of how we might undertake to prevent the onset of late-life depressive conditions. I cannot imagine a book on vascular diseases without a consideration of risk factors that might be addressed (e.g., elevated blood lipids, smoking, overweight, or lack of exercise) to preclude the onset of more serious, function-robbing conditions. In summary, this book well represents what has become the state of the art of geriatric psychiatry early in the 21st century. It is excellent in those elements of biomedicine that it emphasizes and almost devoid of a serious consideration of psychological, social, cultural, and public health perspectives. Eric D. Caine, M.D. University of Rochester Medical Center Rochester, NY 14642 eric_caine@urmc.rochester.edu...查看详细 (3491字节)
☉ 11325830:Anxiety Disorders in Adults: A Clinical Guide
The prevailing system for the diagnosis of anxiety disorders in the United States derives from the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III), published by the American Psychiatric Association in 1980. DSM-III broke with the past in discarding the notion of "neurosis" in favor of an avowedly descriptive and atheoretical approach. Nowhere was the effect of this change greater than in the category of anxiety disorders, which had been classically considered to be neuroses. The current incarnation of the manual, DSM-IV-TR (Text Revision), serves as the point of reference for this book by Vladan Starcevic, an associate professor of psychiatry at the University of Sydney. His intent is to present a "real world" guide to the diagnosis, understanding, and treatment of the anxiety disorders. After a brief conceptual overview, the book devotes a chapter to each of the major anxiety diagnoses (panic, generalized anxiety, social anxiety, specific phobias, obsessive-compulsive disorder, and post-traumatic stress disorder). Each chapter is then organized into sections on clinical features, relationship to other disorders, assessment, epidemiology, course, etiology and pathogenesis, biologic and psychological models, and treatment. The result is a remarkably accessible book that conveys a great deal of clinically useful information. Although expository elegance is not his strength, Starcevic more than compensates for this limitation by focusing on the areas he feels are important, explaining them in comprehensible terms and repeating them if he wants them to stick. He uses many tables to underscore key facts and concepts, and he generally omits the kind of esoterica that only specialists find compelling. This gives the reader the gratifying sense that the book was written to edify rather than to dazzle. Its didactic authority is reinforced by the clear impression one gets that the author has the clinical experience to back up his assertions. His acknowledgment of the kinds of problems often encountered in the translation of textbook recommendations into actual treatment is consistently reassuring. A detailed examination of the historical origins of contemporary approaches to anxiety is not included, nor is a close consideration of current theoretical and diagnostic issues. The attention given to neurobiologic research on anxiety has an obligatory quality, reflecting either the author's lack of enthusiasm or his judgment that these findings are of less immediate clinical relevance than are others. In contrast, Starcevic's discussions of psychological models and therapies are animated and clear, a major strength of the book. One topic that would have benefited from closer treatment is the increasing tendency among clinicians to diagnose post-traumatic stress disorder in patients with borderline personality disorder, an issue that is particularly challenging for practitioners. Anxiety disorders are highly prevalent in the general population as well as in general medical practice. Ironically, though, medical students learn little about them, because the typical required psychiatry clerkship is on an inpatient service, and anxiety disorders do not usually necessitate hospitalization. Accessible as it is, this book deserves a wide readership among those who are going to take care of patients with anxiety disorders, and experienced clinicians will find it to be an engaging review. Lawrence H. Price, M.D. Butler Hospital Providence, RI 02806 lawrence_price_md@brown.edu...查看详细 (3596字节)

☉ 11325831:Remission of Macroglobulinemia during Anastrozole Treatment for Breast Cancer
To the Editor: Waldenstr?m's macroglobulinemia is a lymphoproliferative disorder characterized by a lymphoplasmacytic bone marrow infiltrate and high levels of a monoclonal IgM in serum.1 A number of chemotherapeutic agents and, more recently, monoclonal antibodies have resulted in complete or partial remissions, but the disease remains incurable, with a median survival of five years.1 We first saw our patient in 1996, when she was 71 years of age and had an elevated IgM paraprotein level, which had been found two years earlier. She was asymptomatic, and her lymph nodes and spleen were not enlarged. The IgM level was 22.2 g per liter. A bone marrow aspirate from the posterior iliac crest was diagnostic of Waldenstr?m's macroglobulinemia. Over the course of the next seven years, she remained asymptomatic, with IgM paraprotein levels ranging from 17.5 to 25.0 g per liter. In December 2003, the patient was found to have a focally invasive, grade 3 ductal carcinoma of the breast, with positive axillary lymph nodes. After lumpectomy and axillary dissection, the patient received 5000 cGy of radiation to the right breast, followed by treatment with anastrozole (1 mg daily by mouth) from January 2004 to the present time. When we next saw her, in July 2004, the IgM level had plunged to 0.19 g per liter. The IgM levels were measured monthly for the next eight months, and all measured values were 0.19 g per liter or less, including those obtained from blood drawn and tested at 37°C. The other immunoglobulin levels remained in the normal range. A bone marrow aspirate obtained from the posterior iliac crest in December 2004 showed no sign of macroglobulinemia by morphologic analysis or flow cytometry. Her anastrozole therapy appears to have had no untoward side effects. Anastrozole is a nonsteroidal aromatase inhibitor that blocks the conversion of androgens to estrogens; it has been in use for the treatment of breast cancer since 1995.2 We are unaware of other reports of the use of this agent in Waldenstr?m's macroglobulinemia. In vitro studies of a related condition, multiple myeloma, have shown the presence of estrogen and progesterone receptors on human myeloma cells lines,3 and Kahr et al. have reported a case that suggests a role for androgen deficiency in myeloma proliferation.4 Our patient's clinical course suggests that anastrozole may have had a role in the remission of her Waldenstr?m's macroglobulinemia, and we believe that further investigation is warranted. Crystal Chettle, B.Sc. Michael A. Baker, M.D. University Health Network Toronto, ON M5G 2C4, Canada michael.baker@uhn.on.ca References Ghobrial IM, Gertz MA, Fonseca R. Waldenstrom macroglobulinemia. Lancet Oncol 2003;4:679-685. Baum M, Buzdar AU, Cuzick J, et al. Anastrozole alone or in combination with tamoxifen versus tamoxifen alone for adjuvant treatment of postmenopausal women with early breast cancer: first results of the ATAC randomized trial. Lancet 2002;359:2131-2139. Otsuki T, Yamada O, Kurebayashi J, et al. Estrogen receptors in human myeloma cells. Cancer Res 2000;60:1434-1441. Kahr WH, Al-Homadhi A, Meharchand J, Bailey DJ, Stewart AK. Testicular plasmacytoma following chemical orchiectomy: potential role of hypogonadism in myeloma proliferation. Leuk Lymphoma 1998;28:437-442....查看详细 (3374字节)
☉ 11325832:Pulmonary Adenocarcinomas with Mutant Epidermal Growth Factor Receptors
To the Editor: Activating mutations of the DNA sequence encoding the catalytic kinase domain of the epidermal growth factor receptor (EGFR) have been shown to underlie responsiveness to gefitinib in some cases of non–small-cell lung cancer.1,2,3 Oncogenic mutations in growth factor receptors typically result in constitutive signaling, which increases cell proliferation without requiring the growth factor. In contrast, these mutant EGFR proteins require the ligand.1 This observation raises the possibility that the EGFR ligands — epidermal growth factor and transforming growth factor — are secreted by tumor cells themselves (an autocrine loop) or by surrounding stromal cells (a paracrine loop). Distinguishing between these two models has implications for the design of new treatments. We used immunohistochemistry to identify the cells that contain epidermal growth factor and transforming growth factor in a total of 10 formalin-fixed, paraffin-embedded pulmonary adenocarcinomas, 4 with mutant EGFR proteins and 6 without. The four EGFR alterations included the major mutation types: missense mutations within exon 18 (G719C) and exon 21 (L861Q) and deletions within exon 19 (delL747-P753insS and delL747-T751insS). All specimens containing these mutant receptors showed strong expression of both ligands in the tumor cells but not in the surrounding stromal cells (Figure 1). Similar results were observed in the six cases with wild-type EGFR proteins, in agreement with prior reports.4 Thus, pulmonary adenocarcinomas with EGFR mutations are similar to more common forms of lung cancer, in which autocrine secretion of EGFR ligands by tumor cells stimulates the receptors. The exceptional response of tumors with mutant EGFR proteins to gefitinib most likely results from distinct downstream signaling from the receptor after the ligand binds.5 Our observations raise the possibility that mutations of EGFR arise within a pulmonary epithelial cell that is already secreting epidermal growth factor and transforming growth factor , thus initiating a proliferative stimulus. Figure 1. Autocrine Ligand Expression in Pulmonary Adenocarcinomas. Immunohistochemical analysis (avidin–biotin–peroxidase staining with 3,3-diaminobenzidine tetrahydrochloride as the chromogen and hematoxylin counterstaining in which positive cells stain brown) shows expression of epidermal growth factor (Panel A) and transforming growth factor (Panel B) in a tumor with a mutation of the EGFR gene (delL747-P753insS, in exon 19) resulting in a change in the catalytic domain of the protein. Both ligands are expressed by the tumor cells themselves (i.e., in an autocrine manner), with no expression detected in the stromal cells. Markus J. Riemenschneider, M.D. Daphne W. Bell, Ph.D. Daniel A. Haber, M.D., Ph.D. David N. Louis, M.D. Massachusetts General Hospital Boston, MA 02129 mriemenschneider@partners.org References Lynch TJ, Bell DW, Sordella R, et al. Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small-cell lung cancer to gefitinib. N Engl J Med 2004;350:2129-2139. Paez JG, Janne PA, Lee JC, et al. EGFR mutations in lung cancer: correlation with clinical response to gefitinib therapy. Science 2004;304:1497-1500. Pao W, Miller V, Zakowski M, et al. EGF receptor gene mutations are common in lung cancers from "never smokers" and are associated with sensitivity of tumors to gefitinib and erlotinib. Proc Natl Acad Sci U S A 2004;101:13306-13311. Rusch V, Baselga J, Cordon-Cardo C, et al. Differential expression of the epidermal growth factor receptor and its ligands in primary non-small cell lung cancers and adjacent benign lung. Cancer Res 1993;53:Suppl 10:2379-2385. Sordella R, Bell DW, Haber DA, Settleman J. Gefitinib-sensitizing EGFR mutations in lung cancer activate anti-apoptotic pathways. Science 2004;305:1163-1167....查看详细 (3973字节)
☉ 11325833:Case 35-2004: Nephrogenic Fibrosing Dermopathy
To the Editor: In Case 35-2004, Moschella et al. (Nov. 18 issue)1 discuss a patient with nephrogenic fibrosing dermopathy. There is growing evidence that the fibrosis may not be restricted to the skin but may be systemic, often involving the subcutaneous tissue, fascia, skeletal muscle, heart, lungs, and other organs.2,3,4 This evidence has led us to suggest an alternative name for this disorder — "dialysis-associated systemic fibrosis."3,4 Certain features of the patient discussed in the case suggest that skeletal muscle was involved: progressive weakness, an inability to walk, prominent flexion contractures over the elbows and knees, and the "woody induration" of the feet, which can also occur in the calf and quadriceps muscles.4 We believe a muscle biopsy would have shown endomysial or perimysial fibrosis, or both (Figure 1). We wish to emphasize the occurrence of a systemic fibrotic process in this disorder and to encourage a detailed and careful search for systemic involvement in similar patients. Figure 1. Paraffin-Embedded Tissue Section (Mallory's Trichrome Stain). A specimen of quadriceps muscle obtained at biopsy from a patient with a clinical presentation similar to that of the patient in Case 35-2004 shows excess blue staining around the muscle fibers, which is consistent with perimysial fibrosis. Robert A. Taylor, M.D. University of Iowa Hospitals and Clinics Iowa City, IA 52242 Joshua M. Levine, M.D. Massachusetts General Hospital Boston, MA 02114 Sergio A. Jimenez, M.D. Thomas Jefferson University Philadelphia, PA 19107 sergio.jiminez@jefferson.edu References Case Records of the Massachusetts General Hospital (Case 35-2004). N Engl J Med 2004;351:2219-2227. Ting WW, Stone MS, Madison KC, Kurtz K. Nephrogenic fibrosing dermopathy with systemic involvement. Arch Dermatol 2003;139:903-906. Jimenez SA, Artlett CM, Sandorfi N, et al. Dialysis-associated systemic fibrosis (nephrogenic fibrosing dermopathy): study of inflammatory cells and transforming growth factor beta1 expression in affected skin. Arthritis Rheum 2004;50:2660-2666. Levine JM, Taylor RA, Elman LB, et al. Involvement of skeletal muscle in dialysis-associated systemic fibrosis (nephrogenic fibrosing dermopathy). Muscle Nerve 2004;30:569-577. To the Editor: A registry for nephrogenic fibrosing dermopathy lists more than 150 cases worldwide,1 and data from the registry suggest that a thrombotic complication often reveals unsuspected hypercoagulability and seems to trigger the nephrogenic fibrosing dermopathy.2 Along with fluid overload, hypoxemia and pleural effusions should prompt consideration of a pulmonary embolism in this setting. Disease activity in nephrogenic fibrosing dermopathy seems to parallel worsening renal function (with a lag time of weeks to months). If renal function improves, nephrogenic fibrosing dermopathy tends to improve without any further skin-directed therapy. In the absence of controlled studies, claims of therapeutic efficacy in the setting of improving renal function should be treated with caution. The authors claim that nephrogenic fibrosing dermopathy may follow "a short period of hemodialysis." Approximately 10 percent of cases of nephrogenic fibrosing dermopathy occur in patients who have never undergone dialysis. The implication that dialysis (by association) can cause nephrogenic fibrosing dermopathy is unfortunate, as evinced by several cases in which patients chose to stop dialysis — with fatal consequences. Shawn E. Cowper, M.D. Richard Bucala, M.D., Ph.D. Yale University New Haven, CT 06520 Philip E. LeBoit, M.D. University of California, San Francisco San Francisco, CA 94115 References The International Center for Nephrogenic Fibrosing Dermopathy Research (ICNFDR) home page. (Accessed March 31, 2005, at http://www.icnfdr.org.) Cowper SE. Nephrogenic fibrosing dermopathy: the first 6 years. Curr Opin Rheumatol 2003;15:785-790. The authors reply: We agree with Taylor et al. that the patient's progressive weakness and inability to walk suggest skeletal-muscle involvement. At the time of this clinicopathological conference, skeletal-muscle involvement in nephrogenic fibrosing dermopathy had not yet been described.1 We also have observed an increased incidence of thrombotic complications among the cohort of patients with nephrogenic fibrosing dermopathy that is followed at the Massachusetts General Hospital. We agree with Cowper et al. that hypoxemia and pleural effusions should prompt consideration of pulmonary embolism. However, the resolution of this patient's hypoxemia, pleural effusions, and associated cough after dialysis — with a 17-kg reduction in his body weight — is consistent with fluid overload, not pulmonary embolism. The patient in the Case Records had decreased firmness of his skin and increased range of motion of his knees with thalidomide treatment, in the setting of chronic renal failure that required hemodialysis, without improvement in his renal function. We agree with Cowper et al. that controlled studies of therapy for nephrogenic fibrosing dermopathy should be conducted and should consider changes in renal function. We are aware that nephrogenic fibrosing dermopathy is a systemic disease that often presents with striking induration of the limbs and debilitating flexion contractures. In his discussion of the case, Dr. Moschella referred to an article by Ting et al. on systemic involvement in nephrogenic fibrosing dermopathy.2 He also pointed out that some of the initial 14 patients with nephrogenic fibrosing dermopathy reported in the study by Cowper et al. had not undergone hemodialysis.3 In his observations, Dr. Kay referred to "a short period of hemodialysis" in the context of contrasting the duration of renal failure preceding the onset of nephrogenic fibrosing dermopathy with that preceding the onset of 2-microglobulin amyloidosis, which typically appears after at least five years of dialysis treatment for chronic renal failure.4 Our only reservation about the comments of Taylor et al. is their suggested label of this entity as "dialysis-associated systemic fibrosis."5 Renaming this entity so as to imply that all cases are related to dialysis treatment would be inaccurate, as pointed out by Cowper et al., because nephrogenic fibrosing dermopathy has also developed in several patients who had renal insufficiency but who never underwent dialysis therapy.2 Thus, nephrogenic fibrosing dermopathy is associated more with the inadequately functioning kidney than with renal-replacement therapy. Samuel L. Moschella, M.D. Lahey Clinic Burlington, MA 01805 Jonathan Kay, M.D. Vincent Liu, M.D. Massachusetts General Hospital Boston, MA 02114 References Levine JM, Taylor RA, Elman LB, et al. Involvement of skeletal muscle in dialysis-associated systemic fibrosis (nephrogenic fibrosing dermopathy). Muscle Nerve 2004;30:569-577. Ting WW, Stone MS, Madison KC, Kurtz K. Nephrogenic fibrosing dermopathy with systemic involvement. Arch Dermatol 2003;139:903-906. Cowper SE, Robin HS, Steinberg SM, Su LD, Gupta S, LeBoit PE. Scleromyxoedema-like cutaneous diseases in renal-dialysis patients. Lancet 2000;356:1000-1001. Kay J. 2-microglobulin amyloidosis. Int J Exp Clin Invest 1997;4:187-211. Jimenez SA, Arlett CM, Sandorfi N, et al. Dialysis-associated systemic fibrosis (nephrogenic fibrosing dermopathy): study of inflammatory cells and transforming growth factor beta1 expression in affected skin. Arthritis Rheum 2004;50:2660-2666....查看详细 (7732字节)
☉ 11325834:Cardiovascular Risk and Body-Fat Abnormalities in HIV-Infected Adults
To the Editor: In their review of metabolic and cardiovascular risk factors affecting patients infected with the human immunodeficiency virus (HIV), Grinspoon and Carr (Jan. 6 issue)1 recommend the guidelines of the National Cholesterol Education Program for lipid-lowering therapy in HIV-infected patients with hyperlipidemia. Prediction of coronary heart disease (CHD) with the use of the Framingham equation, however, is based on (and principally predictive for) outpatients free of disease.2 Estimation of the 10-year risk of CHD at any point is based on the person's past and expected future lipid levels (which are best assessed as the area under the curve, as shown in Figure 1). In many treated HIV-infected patients, however, hyperlipidemia does not follow the 10-year course seen in the population without HIV infection, because frequent changes in therapy3,4 may lower total cholesterol levels, increase high-density lipoprotein cholesterol levels, and reduce the risk of atherogenesis.5 Figure 1. Association of Hyperlipidemia and Prediction of the Risk of Coronary Heart Disease over Time. The area under the curve for a person with normal lipid blood levels (thin line) and for another with hyperlipidemia (thick line) contributes to the prediction of the 10-year risk of coronary heart disease at a given point (indicated by the asterisk). Thus, intermittent hyperlipidemia associated with consecutive HIV-therapy regimens (dashed and dotted lines) and the resultant area under the curve differ substantially from risk estimates based on the presence of hyperlipidemia in patients without HIV infection. It seems to be inappropriate simply to reduce risk estimates after treatment interventions for hyperlipidemia, as shown in Table 2 of the article by Grinspoon and Carr.1 Effective statin (or antihypertensive) therapy does not result in the same estimated 10-year risk of CHD as for persons with normal lipid levels or normal blood pressure without therapy. HIV-infected patients with hyperlipidemia and risk factors for CHD before receiving highly active antiretroviral therapy might benefit substantially from lipid-lowering therapy, which should be considered first. Georg M.N. Behrens, M.D. Hannover Medical School 30625 Hannover, Germany behrens.georg@mh-hannover.de References Grinspoon S, Carr A. Cardiovascular risk and body-fat abnormalities in HIV-infected adults. N Engl J Med 2005;352:48-62. Wilson PW, D'Agostino RB, Levy D, Belanger AM, Silbershatz H, Kannel WB. Prediction of coronary heart disease using risk factor categories. Circulation 1998;97:1837-1847. Mocroft A, Ledergerber B, Viard JP, et al. Time to virological failure of 3 classes of antiretrovirals after initiation of highly active antiretroviral therapy: results from the EuroSIDA study group. J Infect Dis 2004;190:1947-1956. Mocroft A, Youle M, Moore A, et al. Reasons for modification and discontinuation of antiretrovirals: results from a single treatment centre. AIDS 2001;15:185-194. van der Valk M, Kastelein JJ, Murphy RL, et al. Nevirapine-containing antiretroviral therapy in HIV-1 infected patients results in an anti-atherogenic lipid profile. AIDS 2001;15:2407-2414. The authors reply: Dr. Behrens notes that prediction of the risk of CHD with the use of the Framingham equation is based on outpatients free of disease. The estimates to which we refer,1 which are based on a large outpatient population of HIV-infected adults, indicate that estimating cardiovascular outcomes with the use of baseline risk factors yielded similar estimated and actual rates. Like Dr. Behrens, we emphasize that such modeling can provide only a relative estimate in the case of young patients with changing lipid levels. We used an estimate of a 25 percent reduction in total cholesterol level to calculate the risk of myocardial infarction in Table 2 of our article,2 as suggested by studies of the use of statins in patients with chronic infection and hyperlipidemia who were receiving antiretroviral therapy.3 Dr. Behrens is correct that our calculations assume that lipid levels will remain relatively constant — they remain stable for up to 96 weeks in HIV-infected patients receiving stable antiretroviral therapy.4 Although an area-under-the-curve approach may provide additional information about patients with changing lipid levels, the Framingham equation is useful to estimate risk, particularly among patients with chronically elevated but stable lipid levels. Steven Grinspoon, M.D. Massachusetts General Hospital Boston, MA 02114 sgrinspoon@partners.org Andrew Carr, M.D. St. Vincent's Hospital 2010 Sydney, Australia References Law MG, D'Arminio Monforte A, Friis-M?ller N, et al. Cardio- and cerebrovascular events and predicted rates of myocardial infarction in the D:A:D Study. Presented at the 11th Conference on Retroviruses and Opportunistic Infections, San Francisco, February 8–11, 2004. Grinspoon S, Carr A. Cardiovascular risk and body-fat abnormalities in HIV-infected adults. N Engl J Med 2005;352:48-62. Calza L, Manfredi R, Chiodo F. Statins and fibrates for treatment of hyperlipidaemia in HIV-infected patients receiving HAART. AIDS 2003;17:851-859. Opravil M, Hirschel B, Lazzarin A, et al. A randomized trial of simplified maintenance therapy with abacavir, lamivudine, and zidovudine in human immunodeficiency virus infection. J Infect Dis 2002;185:1251-1260....查看详细 (5523字节)
☉ 11325835:Pegaptanib and Age-Related Macular Degeneration
To the Editor: Gragoudas and coworkers (Dec. 30 issue)1 report that in a trial of pegaptanib in patients with exudative macular degeneration, patients treated with intravitreal injections of 0.3 mg of active substance had less functional deterioration than did the controls, who received sham injections. It is not clear why the highest concentration (3.0 mg) was less active. Furthermore, if the baseline ocular characteristics of the patients are carefully analyzed, there is a statistically significant difference between the lesions observed in the "best" group of patients, treated with the 0.3-mg dose, and the controls: both the size of choroidal neovascularization and the total lesion size were significantly greater (calculated with the use of Student's t-test) among the controls. Unfortunately, this result could in part explain the differences observed in the end points, since the size of the lesion appears to be more important than other baseline characteristics and larger lesions are associated with a worse prognosis.2 The authors should verify that the size of choroidal revascularization or the total size of the lesion is not a confounding factor in their interpretation. Finally, what grounds do the authors have for suggesting that there is a reduction of neovascular progression with pegaptanib treatment? As shown in Table 4 of their article, the total size of the lesion or the size of choroidal revascularization actually increased by approximately 50 percent after 54 weeks, whatever the treatment. Jean-Marie Rakic, M.D. Pierre Blaise, M.D. Jean-Michel Foidart, M.D. University of Liege Liege 4000, Belgium jmrakic@ulg.ac.be References Gragoudas ES, Adamis AP, Cunningham EJ Jr, et al. Pegaptanib for neovascular age-related macular degeneration. N Engl J Med 2004;351:2805-2816. Blinder KJ, Bradley S, Bressler NM, et al. Effect of lesion size, visual acuity, and lesion composition on visual acuity change with and without verteporfin therapy for choroidal neovascularization secondary to age-related macular degeneration: TAP and VIP report no. 1. Am J Ophthalmol 2003;136:407-418. The authors reply: Dr. Rakic and colleagues pose three questions, to which we supply the following answers. With regard to the first question, the data indicate that all three doses of pegaptanib (0.3 mg, 1.0 mg, and 3.0 mg) are on the plateau of the dose–response curve. The combined analysis demonstrated the efficacy of all the doses, and there was no statistical difference between doses for the primary end point (P0.05 for each interdose comparison). With respect to the second question, baseline measurements of the size of choroidal revascularization and the total size of the lesion differed slightly between the group receiving pegaptanib at a dose of 0.3 mg and the group receiving usual care. These differences were accounted for by prespecifying baseline measures such as lesion size as covariates in the statistical analyses of the primary end point. The cited post hoc exploratory meta-analysis of the use of photodynamic therapy suggested that patients with larger lesions lost more vision than those with smaller lesions.1 In contrast, multiple logistic-regression analysis of the data from the VEGF Inhibition Study in Ocular Neovascularization showed that patients receiving pegaptanib at a dose of 0.3 mg lost less vision, regardless of the size of choroidal revascularization or the lesion size. There is no evidence that the baseline differences in size had an effect on our results. With regard to the third question, the average increase in the size of choroidal revascularization and the total size of the lesion from baseline to week 54 was less among patients treated with pegaptanib than among the controls receiving usual care. Evangelos S. Gragoudas, M.D. Massachusetts Eye and Ear Infirmary Boston, MA 02114 evangelos_gragoudas@meei.harvard.edu Anthony P. Adamis, M.D. Matthew Feinsod, M.D. Eyetech Pharmaceuticals New York, NY 10036...查看详细 (4197字节)
☉ 11325836:Outcomes Associated with a Trial of Labor after Prior Cesarean Delivery
To the Editor: Landon et al. (Dec. 16 issue)1 report an increased risk of hypoxic–ischemic encephalopathy, but not perinatal death, among the infants of women who attempted vaginal birth after prior cesarean delivery as compared with those who underwent planned repeated cesarean delivery. We previously reported an increase by a factor of approximately 12 in the risk of perinatal death in this context2 but have recently shown that there is an inverse relationship between the risk of perinatal death and hospital volume.3 We reanalyzed our data on 124 singleton deliveries complicated by uterine rupture to determine whether neonatal survival after a five-minute Apgar score of less than 4 varied in relation to hospital volume. When hospitals were categorized according to volume (999, 1000 to 1999, 2000 to 2999, 3000 to 3999, and 4000 births per year), the numbers of infants who died were 0 of 4, 0 of 28, 1 of 31, 2 of 26, and 4 of 35, respectively (P for trend = 0.04). The results were similar when the total number of births was used as the denominator. Although they are based on small numbers, these findings suggest that the availability of facilities for immediate delivery and resuscitation of the infant may determine whether catastrophic uterine rupture results in perinatal death or hypoxic–ischemic encephalopathy. In low-volume centers, elective cesarean section may protect primarily against perinatal death, whereas in high-volume centers, such as those studied by Landon et al., elective cesarean section may protect primarily against hypoxic–ischemic encephalopathy. Gordon C.S. Smith, M.D., Ph.D. Cambridge University Cambridge CB2 2SW, United Kingdom gcss2@cam.ac.uk Jill P. Pell, M.D. Greater Glasgow National Health Services Glasgow G3 8YU, United Kingdom References Landon MB, Hauth JC, Leveno KJ, et al. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. N Engl J Med 2004;351:2581-2589. Smith GCS, Pell JP, Cameron AD, Dobbie R. Risk of perinatal death associated with labor after previous cesarean delivery in uncomplicated term pregnancies. JAMA 2002;287:2684-2690. Smith GCS, Pell JP, Pasupathy D, Dobbie R. Factors predisposing to perinatal death related to uterine rupture during attempted vaginal birth after caesarean section: retrospective cohort study. BMJ 2004;329:375-375. To the Editor: Landon et al. report important findings of a large prospective study on the risks of a trial of labor after prior cesarean delivery. These findings are consistent with those of previous studies1,2 with regard to the increased risk of maternal and perinatal complications, and Landon et al. report the additional finding that use of either oxytocin or prostaglandins significantly increases the risk of uterine rupture. The analysis, however, does not stratify the risk of complications according to the number of previous cesarean deliveries or the number of weeks of gestation. Other studies3,4 have shown that the risk of uterine rupture during labor is nearly five times as great for women with more than one previous cesarean delivery as it is for women with only one previous cesarean delivery. The studies also showed a significantly decreased risk of fetal or neonatal death for women with only one previous cesarean section and less than 42 weeks of gestation. The guidelines of the American College of Obstetricians and Gynecologists5 consider two uterine scars and no vaginal deliveries to be a contraindication to a trial of labor. Stratification of the findings of Landon et al. according to the number of cesarean deliveries and the number of weeks of gestation is essential to interpret the findings and appropriately counsel women regarding the risks of a trial of labor after prior cesarean delivery. Deborah L. Kaplan, R.P.A., M.P.H. New York City Department of Health and Mental Hygiene New York, NY 10007 dkaplan@health.nyc.gov References Hibbard JU, Ismail MA, Wang Y, Te C, Karrison T, Ismail MA. Failed vaginal birth after a cesarean section: how risky is it? Am J Obstet Gynecol 2001;184:1365-1371. Mozurkewich EL, Hutton EK. Elective repeat cesarean delivery versus trial of labor: a meta-analysis of the literature from 1989 to 1999. Am J Obstet Gynecol 2000;183:1187-1197. Caughey AB, Shipp TD, Repke JT, Zelop CM, Cohen A, Lieberman E. Rate of uterine rupture in women with one or two prior cesarean deliveries. Am J Obstet Gynecol 1999;181:872-876. Lieberman E, Ernst EK, Rooks JP, Stapleton S, Flamm B. Results of the national study of vaginal birth after cesarean in birth centers. Obstet Gynecol 2004;104:933-942. ACOG Practice Bulletin 54: vaginal birth after previous cesarean delivery. Obstet Gynecol 2004;104:203-212. To the Editor: The article by Landon et al. is one of a series of reports over the past five years that address the problems arising among women who undergo a trial of labor after prior cesarean delivery. Examination of the database of the National Perinatal Information Center highlights the effect these reports have had on a subgroup of centers during the period from 1999 to 2003. From the total of 654,095 low-risk, singleton deliveries among women with a prior uterine scar, the rate of repeated cesarean section increased by 31.7 percent, from 61.8 percent in 1999 to 81.4 percent in 2003. Since "delivery" is the most common hospital procedure, changes in the type of delivery have a significant effect on resource utilization and on cost. For hospitals with a high percentage of payers reimbursing on the basis of one rate, regardless of the type of delivery, the fear is that the additional staff and resources needed to meet the increasing demand for cesarean sections will widen the gap between reimbursement and cost. The perinatal community must work to ensure that reimbursement responds to the current trend. David E. Gagnon, M.P.H. Janet H. Muri, M.B.A. National Perinatal Information Center Providence, RI 02906 dgagnon@npic.org To the Editor: Landon et al. included stillbirth, neonatal death, and perinatal hypoxic–ischemic encephalopathy in the category of perinatal outcomes. However, the risks of other outcomes, such as transient tachypnea of the newborn, the respiratory distress syndrome, persistent pulmonary hypertension, and a stay in the neonatal intensive care unit, have been reported to be higher among infants who were born after elective cesarean section than among those born after a trial of labor.1,2 At times, severe respiratory failure in infants has progressed to the point where extracorporeal membrane oxygenation was required.3 These outcomes have a considerable effect in terms of mother–infant bonding, successful establishment of breast-feeding, and costs. Alternatively, infants born by cesarean section after a trial of labor are at increased risk of having septic evaluations and requiring antibiotic therapy.1 These data should also be incorporated into the information provided as part of counseling for women and preparing them for potential risks and benefits. It may be a worthwhile exercise to conduct a cost-effectiveness analysis that includes these outcomes and the effect of a stay in the neonatal intensive care unit based on the number needed to treat for elective cesarean section, which was relatively high in the study by Landon et al. Prakeshkumar S. Shah, M.D. Mount Sinai Hospital Toronto, ON M5G 1X5, Canada pshah@mtsinai.on.ca References Hook B, Kiwi R, Amini SB, Fanaroff A, Hack M. Neonatal morbidity after elective repeat cesarean section and trial of labor. Pediatrics 1997;100:348-353. Heritage CK, Cunningham MD. Association of elective repeat cesarean delivery and persistent pulmonary hypertension of the newborn. Am J Obstet Gynecol 1985;152:627-629. Keszler M, Carbone MT, Cox C, Schumacher RE. Severe respiratory failure after elective repeat cesarean delivery: a potentially preventable condition leading to extracorporeal membrane oxygenation. Pediatrics 1992;89:670-672. The authors reply: Smith and Pell propose that differences in the annual number of deliveries may explain discrepancies between their finding of an increase in the risk of perinatal death associated with a trial of labor after prior cesarean delivery, as compared with planned repeated cesarean delivery,1,2 and our finding of an increase in the risk of hypoxic–ischemic encephalopathy (but not perinatal death) with a trial of labor. The smallest participating center in our study performed approximately 3000 deliveries per year. We agree with these authors that it is plausible that larger institutions may provide a level of support and expertise in response to obstetric emergencies such as uterine rupture that may result in better outcomes. Alternatively, our population may have been at inherently lower risk for adverse outcomes, since a trial of labor was undertaken in 39 percent of our population as compared with 63 percent in the study by Smith et al. In response to Kaplan's comments, we are currently in the process of comparing outcomes in women with multiple prior cesarean deliveries with those in women with a single prior cesarean delivery. As noted in our article, of the 671 women at term who had more than one prior cesarean section and who underwent a trial of labor, none had infants with hypoxic–ischemic encephalopathy. We had only 365 cases in which women who were at 42 weeks of gestation or more attempted vaginal birth after a prior cesarean delivery.3,4 In response to Gagnon and Muri, the potential economic burden of an increasing rate of repeated cesarean delivery is debatable. Cost analyses have challenged the widely accepted opinion that cesarean deliveries are more expensive than vaginal childbirth.5 Since the cost and complications of a failed trial of labor exceed the cost of an elective cesarean, practitioners must consider potential success rates as vital to the counseling of women who are considering their options for delivery after prior cesarean section. In response to Shah's comments, we agree that rates of respiratory disorders and requirements for neonatal intensive care are relevant in assessing the benefits versus the costs of elective repeated cesarean delivery. In our study, the number of admissions to the neonatal intensive care unit for term infants in the group of women who underwent a trial of labor was 1399 of 15,338 (9.1 percent) as compared with 1325 of 15,014 (8.8 percent) for those undergoing repeated cesarean delivery (P=0.34); the numbers for transient tachypnea of the newborn were 396 (2.6 percent) and 541 (3.6 percent), respectively (P<0.001). We did not collect data on the overall frequency of septic evaluations and antibiotic therapy in the neonates. Mark B. Landon, M.D. Ohio State University College of Medicine Columbus, OH 43210-1228 landon.1@osu.edu Sharon Leindecker, M.S., M.B.A. George Washington University Biostatistics Center Rockville, MD 20852 Catherine Y. Spong, M.D. National Institute of Child Health and Human Development Bethesda, MD 20892 References Smith GC, Pell JP, Cameron AD, Dobbie R. Risk of perinatal death associated with labor after previous cesarean delivery in uncomplicated term pregnancies. JAMA 2002;287:2684-2690. Smith GCS, Pell JP, Pasupathy D, Dobbie R. Factors predisposing to perinatal death related to uterine rupture during attempted vaginal birth after caesarean section: retrospective cohort study. BMJ 2004;329:375-375. ACOG Practice Bulletin 54: vaginal birth after previous cesarean delivery. Obstet Gynecol 2004;104:203-212. Caughey AB, Shipp TD, Repke JT, Zelop CM, Cohen A, Lieberman E. Rate of uterine rupture in women with one or two prior cesarean deliveries. Am J Obstet Gynecol 1999;181:872-876. Macario A, El-Sayed YY, Druzin ML. Cost-effectiveness of a trial of labor after previous cesarean delivery depends on the a priori chance of success. Clin Obstet Gynecol 2004;47:378-385....查看详细 (12217字节)
☉ 11325837:Clopidogrel versus Aspirin and Esomeprazole to Prevent Recurrent Bleeding
To the Editor: Chan et al. (Jan. 20 issue)1 conclude that aspirin plus a proton-pump inhibitor is superior to clopidogrel in the prevention of recurrent ulcer bleeding. The authors of the study and Cryer, in an accompanying editorial,2 state that the current American College of Cardiology–American Heart Association (ACC–AHA) guidelines, which recommend that aspirin be replaced with clopidogrel in patients who have a history of gastrointestinal complications, are harmful and that such patients should be given aspirin plus a proton-pump inhibitor. The ACC–AHA guidelines state, "Clopidogrel should be administered to hospitalized patients who are unable to take ASA [acetylsalicylic acid] because of hypersensitivity and major gastrointestinal intolerance."3 This recommendation is based on the 8.7 percent reduction in the relative risk of cardiovascular events with clopidogrel as compared with acetylsalicylic acid in the Clopidogrel versus Aspirin in Patients at Risk of Ischaemic Events (CAPRIE) trial.4 The CAPRIE trial excluded patients with a history of gastrointestinal bleeding and reported lower rates of gastrointestinal bleeding or ulcers in the clopidogrel group than in the aspirin group. Of note, the guidelines do not imply that patients with a history of major gastrointestinal intolerance of aspirin should receive clopidogrel without appropriate treatment for their gastrointestinal condition. Such general medical decisions are beyond the scope of the guidelines. The use of proton-pump inhibitors in patients with a history of bleeding ulcers is known to reduce ulcer complications.5,6 Therefore, we are disturbed by the scientific rationale and questionable design of the current trial, in which the clopidogrel group did not receive a proton-pump inhibitor. We do not find the results in conflict with the current guidelines, but we will review the results as part of the regular process of updating all of our guidelines. Michael J. Wolk, M.D. American College of Cardiology Foundation Bethesda, MD 20814-1699 Alice K. Jacobs, M.D. American Heart Association Dallas, TX 75231-4596 References Chan FKL, Ching JYL, Hung LCT, et al. Clopidogrel versus aspirin and esomeprazole to prevent recurrent ulcer bleeding. N Engl J Med 2005;352:238-244. Cryer B. Reducing the risks of gastrointestinal bleeding with antiplatelet therapies. N Engl J Med 2005;352:287-289. Braunwald E, Antman EM, Beasley JW, et al. ACC/AHA 2002 guideline update for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction -- summary article: a report of the American College of Cardiology/American Heart Association task force on practice guidelines (Committee on the Management of Patients with Unstable Angina). J Am Coll Cardiol 2002;40:1366-1374. CAPRIE Steering Committee. A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). Lancet 1996;348:1329-1339. Lai KC, Lam SK, Chu KM, et al. Lansoprazole for the prevention of recurrences of ulcer complications from long-term low-dose aspirin use. N Engl J Med 2002;346:2033-2038. Leontiadis GI, Sharma VK, Howden CW. Systematic review and meta-analysis of proton pump inhibitor therapy in peptic ulcer bleeding. BMJ 2005;330:568-568. To the Editor: Chan et al. state that their findings do not support the current ACC–AHA guidelines, which recommend the use of clopidogrel in patients with gastrointestinal intolerance to aspirin. Their findings are based on a study of only 320 patients who initially presented with gastrointestinal ulcerations. Because patients in the clopidogrel group were not given a proton-pump inhibitor, there is little question as to which group was going to have higher rates of bleeding. The question that begs to be answered, however, is how such a study could receive approval by an institutional review board. Denying prophylactic therapy to patients at high risk for the development of bleeding is completely unethical. Furthermore, on the basis of the results of two trials, the manufacturers of clopidogrel warn against its use in patients with a recent history of ulcers.1,2,3 To suggest, indirectly, that the ACC–AHA guidelines be revised is unfounded and is counterproductive to the care each year of hundreds of thousands of patients with acute coronary syndromes. A larger, properly designed trial needs to be conducted before such a conclusion is made. Kurt A. Wargo, Pharm.D. Auburn University Harrison School of Pharmacy Auburn, AL 36830 wargoka@auburn.edu Sharon R. Baty, Pharm.D. Gregg Knowles, Pharm.D. Huntsville Hospital Huntsville, AL 35801 References CAPRIE Steering Committee. A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). Lancet 1996;348:1329-1339. The Clopidogrel in Unstable Angina to Prevent Recurrent Events Trial Investigators. Effects of clopidogrel in addition to aspirin in patients with acute coronary syndromes without ST-segment elevation. N Engl J Med 2001;345:494-502. Plavix (clopidogrel bisulfate). New York: Bristol-Myers Squibb/Sanofi Pharmaceuticals, 2003 (package insert). To the Editor: As a pharmacist working in a large grocery-store chain, I see on a daily basis patients who have to choose between buying groceries and paying for their prescriptions. I must admit that I was rather encouraged to read the findings reported by Chan et al. The use of a proton-pump inhibitor and aspirin, rather than clopidogrel, would in effect save each patient more than $100 per month in prescription costs alone. The average cost of 30 tablets of clopidogrel is about $137; in comparison, a bottle of over-the-counter aspirin and a box of over-the-counter omeprazole together cost less than $30. Peter R. Barski, Jr., Pharm.D. 18967 SE Bryant Dr. Jupiter, FL 33469 jordanbarski@bellsouth.net Dr. Chan replies: Our institutional review board approved this study on the basis of the ACC–AHA guidelines, which indicate that clopidogrel should be administered to hospitalized patients who cannot take aspirin because of major gastrointestinal intolerance (a class IA recommendation). In Australia, one approved indication for clopidogrel is the secondary prevention of atherosclerotic events in patients in whom aspirin poses an unacceptable risk of gastrointestinal bleeding.1 The manufacturers warn against the use of clopidogrel in patients with an active peptic ulcer only, not a recent history of ulcer.2 All our patients were confirmed to have healed ulcers before they were enrolled. If clopidogrel does not damage the stomach, what is the rationale for using prophylactic therapy? In the absence of an active peptic ulcer or concomitant use of aspirin or nonsteroidal antiinflammatory drugs, we cannot agree with Wargo and colleagues' criticism — that denying prophylactic therapy to our patients receiving clopidogrel was unethical. The high rate of recurrent bleeding in the clopidogrel group was unexpected. The ACC–AHA use the results of the CAPRIE trial3 to justify their guidelines. The real question that begs to be answered is whether the evidence is good enough to justify a class IA recommendation. The CAPRIE trial was not designed to compare the gastrointestinal safety of clopidogrel with that of aspirin. Gastrointestinal bleeding was not a predefined end point. We cannot accept a class IA recommendation solely on the basis of a post hoc subgroup analysis. Can we infer from this subgroup analysis that clopidogrel carries a lower risk of gastrointestinal bleeding than aspirin? In the CAPRIE trial, the incidence of gastrointestinal bleeding in the aspirin group (dose of aspirin, 325 mg per day) was 1.3 times that in the clopidogrel group. This comparison, however, was unfair because the risk of gastrointestinal bleeding with 325 mg of aspirin per day is almost double that with 81 mg of aspirin per day.4 The ACC–AHA argued that the decision regarding use of prophylactic therapy was beyond the scope of their guideline. If prophylactic therapy is still required in patients receiving clopidogrel because of intolerance to aspirin, what is the advantage of using clopidogrel and a proton-pump inhibitor rather than aspirin and a proton-pump inhibitor? We do not deny the benefits of the combination of clopidogrel and aspirin for patients with acute coronary syndromes. Clopidogrel alone, however, is only marginally superior to aspirin for cardiovascular protection.5 Our message is simple. For patients who can benefit from aspirin alone, switching to clopidogrel because of aspirin intolerance is expensive, unfounded, and counterproductive. They should continue to take aspirin and receive a proton-pump inhibitor. Francis K.L. Chan, M.D. Chinese University of Hong Kong Hong Kong, China fklchan@cuhk.edu.hk for the Gastrointestinal Research Group References Kubler PA, Pillans PI, Marrinan MC, Frogley M. Concordance between clopidogrel use and prescribing guidelines. Intern Med J 2004;34:663-667. Plavix (clopidogrel bisulfate). New York: Bristol-Myers Squibb/Sanofi Pharmaceuticals, 2003 (package insert). CAPRIE Steering Committee. A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). Lancet 1996;348:1329-1339. Weil J, Colin-Jones D, Langman M, et al. Prophylactic aspirin and risk of peptic ulcer bleeding. BMJ 1995;310:827-830. Antithrombotic Trialists' Collaboration. Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ 2002;324:71-86....查看详细 (9861字节)
☉ 11325839:Infection, Antibiotics, and Atherothrombosis — End of the Road or New Beginnings?
Two large, high-quality, and convincingly negative clinical trials for the secondary prevention of coronary heart disease,1,2 published in this issue of the Journal, raise questions as to whether we are at the end of the road or should move on to new beginnings as we explore the hypothesis that infection plays a role in atherosclerosis. Evidence that vascular inflammation is an important mechanism involved in all stages of atherogenesis continues to accumulate. Such evidence has legitimately raised the question of whether infection is one of the inflammatory stimuli that operate in the pathophysiology of atherothrombosis, either locally, within vascular tissue, or systemically, through inflammatory mediators.3 Furthermore, data from animal models and seroepidemiologic and pathological observations have raised the possibility that Chlamydia pneumoniae, a species of intracellular gram-negative bacterium, might be an infectious vector of atherogenesis and, hence, a target for therapy. C. pneumoniae is an obligate microbe that commonly causes respiratory infection, is frequently found in atherosclerotic plaque, and is susceptible to macrolide and quinolone antibiotics.3 Indeed, studies in animal models have demonstrated that C. pneumoniae can accelerate atherogenesis and that antibiotics can suppress it.3 Initial clinical studies from the United Kingdom4 and Argentina5 reported that antibiotic therapy might lead to large reductions in secondary cardiovascular risk in patients with stable coronary heart disease or acute coronary syndromes. Subsequent work by my colleagues and me6 and, later, by others in studies of intermediate size7,8,9,10 failed to confirm a large benefit (Table 1). However, these studies left open the possibility of limited-to-moderate clinical benefits (i.e., risk reductions of 20 to 30 percent), which would require testing in trials involving several thousand patients. Table 1. Large and Intermediate-Size Trials of Antibiotics for the Secondary Prevention of Coronary Heart Disease. Subsequently, the Weekly Intervention with Zithromax for Atherosclerosis and its Related Disorders (WIZARD) study, a megatrial involving 7724 patients with stable disease who had a history of myocardial infarction and serologic evidence of C. pneumoniae, failed to find a long-term benefit, even though a favorable trend was noted during and shortly after a three-month course of treatment with azithromycin.11 Similarly, with regard to acute coronary syndromes, the Azithromycin in Acute Coronary Syndromes study (AZACS), a moderately large trial involving 1439 patients, did not show a benefit, but its conclusions were limited by its short duration of therapy (azithromycin for five days).10 To these earlier trials, the Azithromycin and Coronary Events Study (ACES)1 and the Pravastatin or Atorvastatin Evaluation and Infection Therapy–Thrombolysis in Myocardial Infarction (PROVE IT–TIMI) trial2 add major new information. The ACES trial1 which was sponsored by the National Institutes of Health, was a randomized, double-blind, placebo-controlled trial involving 4012 adults with stable coronary heart disease who were enrolled without regard to their serologic C. pneumoniae status. Participants received weekly azithromycin or placebo for one year. The mean period of follow-up was four years. The primary end point, a composite of death due to coronary heart disease, nonfatal myocardial infarction, hospitalization for unstable angina, or coronary revascularization, occurred in 22.4 percent of the patients who received placebo and 22.3 percent of those who received azithromycin — a relative-risk reduction of less than 1 percent, with narrow confidence intervals (–13 percent to 13 percent). Furthermore, unlike the WIZARD trial, ACES showed no trend toward an early benefit during the period of active therapy. Individual components of the primary end point and the secondary end points were unaffected. The frequency of gastrointestinal side effects increased to some extent. The investigators concluded that azithromycin, even when given regularly for one year, is ineffective for the prevention of secondary cardiovascular events. The PROVE IT–TIMI study,2 a double-blind, randomized, two-by-two factorial trial involving 4162 patients at multiple centers, addressed two complementary issues: the secondary prevention of cardiovascular events after acute coronary syndromes and, in addition, antibiotic therapy with gatifloxacin, a potentially more efficacious antibiotic than azithromycin. Results of the first randomization, which involved intensive as compared with moderate reductions in lipid levels, have been reported previously. The second randomization compared the results of treatment with gatifloxacin and placebo, given, after initial dosing, for 10 days each month during a follow-up period of 18 to 32 months (mean, 24 months). The primary end point — a composite of death from any cause, myocardial infarction, unstable angina requiring hospitalization, revascularization performed at least 30 days after randomization, or stroke — occurred in 25.1 percent of the patients who received placebo and 23.7 percent of those who received gatifloxacin; this represented a 5 percent reduction in the hazard ratio, an insignificant difference with narrow confidence intervals (–8 percent to 16 percent). No benefits were noted in any major subgroup, including those stratified according to the level of C-reactive protein or C. pneumoniae seropositivity. Antibiotic therapy reduced the incidence of upper respiratory infection, but it caused more gastrointestinal side effects, and it did not reduce C-reactive protein levels. The investigators concluded that gatifloxacin, even when given over the long term, is ineffective for the secondary prevention of cardiovascular events after acute coronary syndromes. The expectation that these antibiotic trials might provide insight into the validity (or fallacy) of the infection hypothesis must be tempered by consideration of important limitations and uncertainties. Such drawbacks suggest that the hypothesis does not easily lend itself to proof or disproof according to Koch's classic postulates. Even if studies yield positive results, the hypothesis is not entirely proved, because nonspecific antiinflammatory effects or antiinfective actions against other organisms might be operative. Antibiotic intervention targeted to C. pneumoniae through the prevention of typical periodontal, respiratory tract, and urinary tract infections could prevent the progression of cardiovascular disease if the treatment suppressed infection-related, circulating inflammatory mediators of atherothrombosis. Indeed, that there is an infection-related increase in the risk of myocardial infarction and stroke was strongly supported by a recent study in the Journal.12 Moreover, tetracyclines (e.g., minocycline and doxycycline), which have been touted for the treatment of a variety of inflammatory conditions, including rheumatoid arthritis, chronic periodontitis, and acute coronary syndromes, may have anti–matrix metalloproteinase activity in doses even lower than those for antimicrobial uses; this activity could represent a mechanism of potential benefit unrelated to antibiotic effects. Negative outcomes, which have been noted in most of the recent studies (Table 1), might be explained not only by the use of an incorrect hypothesis (i.e., that infection is not atherogenic) but also by an inadequate sample size or by the use of an ineffective antibiotic regimen. The ACES and PROVE IT–TIMI trials address most of the concerns about study design, including sample size (and its effect on the power of the study) and the duration of therapy, but they leave open the possibility of ineffectiveness. Indeed, Gieffers et al. found that C. pneumoniae infection in vitro in monocytes from healthy volunteers or in vivo in circulating monocytes from patients who had been treated for coronary heart disease was refractory to azithromycin13: antibiotic treatment did not inhibit chlamydial growth within monocytes, and after withdrawal of antibiotic therapy, C. pneumoniae could be cultured from monocyte cell lines. In contrast, antibiotics eliminated C. pneumoniae from epithelial cells.13 Whether gatifloxacin would perform better is uncertain. Hence, whereas ACES and PROVE IT–TIMI, together with other studies (Table 1), appear conclusively to eliminate azithromycin, gatifloxacin, and related agents as useful preventive therapies for secondary cardiovascular events, they leave open the possibility that novel antibiotics with more potent bactericidal activity against intracellular microbes could lead to a different outcome.14 However, event rates in ACES and PROVE IT–TIMI were unaffected even during the long periods of ongoing (and presumably suppressive) therapy. Hence, another reason for a negative trial result should be considered: that an advanced, unmodifiable stage of disease was chosen for study. A large body of negative clinical-trial results suggests that antibiotics effective for clinical C. pneumoniae infection are not useful for secondary prevention (Table 1). The testing of these agents for the treatment of advanced coronary heart disease appears to be at the end of the road. On the other hand, evidence that infection can be a stimulus for atherothrombosis continues to mount.3,12,15 These positive observations suggest that we should rethink, revise, and reformulate hypotheses and research strategies — that is, that we should begin anew, rather than discard the possibility of infection as an etiologic factor. We should focus on expanding our limited knowledge base with regard to proatherogenic mechanisms (including viral vectors); we should include sophisticated preclinical models in our research plans; and, when appropriate, we should return to the clinical arena with trials that better select target patients (e.g., those at an earlier stage of atherosclerosis or those with better markers of latent or active infection or with a high total or viral burden3) and interventions, including novel antiinfective agents and vaccines.3,14,15 Meanwhile, standard antibiotics do not work for the secondary prevention of cardiovascular heart disease. Source Information From the University of Utah School of Medicine, LDS Hospital, Salt Lake City. References Grayston JT, Kronmal RA, Jackson LA, et al. Azithromycin for the secondary prevention of coronary events. N Engl J Med 2005;352:1637-1645. Cannon CP, Braunwald E, McCabe CH, et al. Antibiotic treatment of Chlamydia pneumoniae after acute coronary syndrome. N Engl J Med 2005;352:1646-1654. Anderson JL, Muhlestein JB. The role of infection. In: Theroux P, ed. Acute coronary syndromes: a companion to Braunwald's Heart Disease. Philadelphia: Saunders, 2003:88-107. Gupta S, Leatham EW, Carrington D, Mendall MA, Kaski JC, Camm AJ. Elevated Chlamydia pneumoniae antibodies, cardiovascular events, and azithromycin in male survivors of myocardial infarction. Circulation 1997;96:404-407. Gurfinkel E, Bozovich G, Daroca A, Beck E, Mautner B. Randomised trial of roxithromycin in non-Q-wave coronary syndromes: ROXIS Pilot Study. Lancet 1997;350:404-407. Muhlestein JB, Anderson JL, Carlquist JF, et al. Randomized secondary prevention trial of azithromycin in patients with coronary artery disease: primary clinical results of the ACADEMIC study. Circulation 2000;102:1755-1760. Neumann F, Kastrati A, Miethke T, et al. Treatment of Chlamydia pneumoniae infection with roxithromycin and effect on neointima proliferation after coronary stent placement (ISAR-3): a randomised, double-blind, placebo-controlled trial. Lancet 2001;357:2085-2089. Sinisalo J, Mattila K, Valtonen V, et al. Effect of 3 months of antimicrobial treatment with clarithromycin in acute non-Q-wave coronary syndrome. Circulation 2002;105:1555-1560. Zahn R, Schneider S, Frilling B, et al. Antibiotic therapy after acute myocardial infarction: a prospective randomized study. Circulation 2003;107:1253-1259. Cercek B, Shah PK, Noc M, et al. Effect of short-term treatment with azithromycin on recurrent ischaemic events in patients with acute coronary syndrome in the Azithromycin in Acute Coronary Syndrome (AZACS) trial: a randomised controlled trial. Lancet 2003;361:809-813. O'Connor CM, Dunne MW, Pfeffer MA, et al. Azithromycin for the secondary prevention of coronary heart disease events: the WIZARD study: a randomized controlled trial. JAMA 2003;290:1459-1466. Smeeth L, Thomas SL, Hall AJ, Hubbard R, Farrington P, Vallance P. Risk of myocardial infarction and stroke after acute infection or vaccination. N Engl J Med 2004;351:2611-2618. Gieffers J, Fullgraf H, Jahn J, et al. Chlamydia pneumoniae infection in circulating human monocytes is refractory to antibiotic treatment. Circulation 2001;103:351-356. Roblin PM, Reznik T, Kutlin A, Hammerschlag MR. In vitro activities of rifamycin derivatives ABI-1648 (rifalazil, KRM-1648), ABI-1657, and ABI-1131 against Chlamydia trachomatis and recent clinical isolates of Chlamydia pneumoniae. Antimicrob Agents Chemother 2003;47:1135-1136. Madjid M, Naghavi M, Litovsky SA, Casscells SW. Influenza and cardiovascular disease: a new opportunity for prevention and the need for further studies. Circulation 2003;108:2730-2736....查看详细 (13499字节)
☉ 11325840:Case 12-2005 — A 30-Year-Old Woman with a Mediastinal Mass
Presentation of Case Dr. Rameen Beroukhim (Medical Oncology): A 30-year-old woman was admitted to the hospital because of a fever and a mediastinal mass. The patient had been in her usual state of health until two months before admission, when pain developed in her left shoulder, arm, and chest, without trauma. She was seen by a nurse practitioner at another facility. On examination, there was tightness of the left trapezius muscle and tenderness to palpation along the costochondral junction. She was treated with ibuprofen, heat, and massage and asked to return if the symptoms worsened. One month before admission, the patient came to the emergency department of this hospital with persistent left-sided pleuritic chest pain, which radiated from her chest to her shoulder; increased with cough, inspiration, and palpation; and was associated with a cough that was occasionally productive of blood. The vital signs were normal. Breath sounds were decreased on the left side, with splinting and tenderness to palpation. The results of a complete blood count, the levels of serum electrolytes, and results of tests of renal function were normal. A chest radiograph showed consolidation in the lingula of the left lung. The left hilum appeared enlarged, suggesting adjacent air-space disease or lymphadenopathy. She was treated with ibuprofen, levofloxacin (daily for one week), and oxycodone as needed for pain, with follow-up planned for one week, or sooner if symptoms worsened. One week later, she was seen at a follow-up appointment by her primary care physician. Her condition was only slightly improved, and she continued to cough, but no hemoptysis was present. A tuberculin skin test was administered, and two days later the result was negative. Nineteen days before admission, computed tomographic (CT) scanning of the chest was performed after the intravenous administration of contrast material. Dr. Suzanne L. Aquino: The initial chest radiograph shows an air-space opacity in the left midlung area that overlies the left hilar region (Figure 1). There is soft-tissue fullness in the left side of the mediastinum overlying the hilum on this single frontal view, suggesting lymphadenopathy or a mass in the area. Figure 1. Chest Radiograph. The initial chest radiograph shows soft-tissue fullness (arrow) along the left hilum and mediastinum that obscures the hilar anatomy. There is an air-space opacity in the middle left lung. A CT scan of the thorax shows a mass, 7.9 cm by 10.4 cm, in the anterior mediastinum (Figure 2A). This soft-tissue mass has areas of low attenuation, suggesting necrosis, and it abuts the right ventricle. There is a small nodule, 1.4 cm in diameter, in the adjacent lingula (Figure 2B). On the lung windows, there is a mixture of both consolidation and ground-glass opacities in the left lung, especially the left upper lobe, with associated thickened interlobular septa. None of the airways or vascular structures were obstructed. Figure 2. CT Scans of the Thorax. The initial CT scan (Panel A) of the thorax shows a large mass with low attenuation foci (arrow) that suggests central necrosis. The mass extends anterior to the right ventricle (Panel B). A lingular nodule (arrow) abuts the mediastinal mass. Another CT scan obtained 17 days later (Panel C) shows an increase in the size of the anterior mediastinal mass. There is increased mass effect (Panel D) on the right ventricle (arrow). The adjacent lingular nodule has also increased in size (arrowhead). Dr. Beroukhim: The next day, the patient embarked on a long-planned two-week vacation, against the advice of her physician. Upon her return, four days before admission, bronchoscopy with bronchoalveolar lavage and transbronchial needle biopsies was performed, on an outpatient basis. The left upper lobe and lingular carinal junction was splayed, and small amounts of blood were present in the left upper and left lower lobe orifices. Histologic examination of multiple biopsy specimens showed necrotic tissue. The fluid obtained was orange and moderately turbid. Cytologic examination revealed bronchial cells and foamy histiocytes, some with intracytoplasmic hemosiderin; no malignant cells were seen. A Gram's stain of the lavage fluid showed no organisms or leukocytes, and the results of an acid-fast smear and fungal wet preparation were negative. Fluid was sent for cultures for respiratory organisms, mycobacteria, and fungi. Two days before admission, the patient returned to the emergency department with increased pain in the left side of the chest and shortness of breath. Additional imaging studies were obtained. Dr. Aquino: A chest radiograph shows an increase in air-space opacity in the left lung, with soft-tissue fullness overlying the left hilum and mediastinum. A follow-up CT scan obtained at this time shows that both the mediastinal mass (Figure 2C) and the lingular nodule (Figure 2D) have also increased in size. There is an increase in the mass effect on the right ventricle outflow tract by this enlarging tumor. The air-space disease in the left lung has increased. Dr. Beroukhim: The hematocrit was 31.8 percent and the hemoglobin level 10.9 g per deciliter; the remainder of the results of the complete blood count, the levels of electrolytes, and the results of renal-function tests were normal. The next day, the patient returned to the pulmonary clinic. The pain was somewhat improved. There was tenderness to palpation over the left side, from the fifth to the eighth ribs. There were diminished breath sounds in the left lung; the right lung was clear. She had pain when lying down; possibly because of this discomfort, she had an awkward gait. The rest of the examination showed no abnormalities. A Gram's stain of a sputum specimen showed abundant leukocytes and mixed gram-positive and gram-negative organisms, with no predominant organism. On the day of admission, when the patient was seen for a scheduled appointment in the thoracic surgery clinic, she said that she had had fevers and chills since the previous night. She had had hemoptysis every six hours, pain in the left side of the chest wall and left arm, and poor appetite and fluid intake. The temperature was 38.9°C, and she was admitted to this hospital from the emergency department for further evaluation and treatment. The patient had been well until this illness. She had immigrated to the United States from Puerto Rico 19 years before admission. She was a homemaker and lived with her husband and children. She did not smoke, consume alcohol, or use drugs intravenously. A sister had received a liver transplant at seven years of age because of hepatitis; her mother had diabetes mellitus; and her maternal grandmother had had cervical cancer. Her medications were oxycodone, for pain, and levofloxacin. On physical examination, she appeared ill, with sunken eyes and cheeks. The temperature was 36.8°C, the blood pressure 98/61 mm Hg, the pulse 99 beats per minute, the respiratory rate 18 breaths per minute, and the oxygen saturation 97 percent while the patient was breathing ambient air. There was no peripheral lymphadenopathy. There were decreased breath sounds in the upper lobe of the left lung, and there was diffuse chest-wall and back pain to palpation. There was a pulsus paradoxus of 4 mm Hg; a jugular venous pressure of 7 cm, with Kussmaul's sign; and a positive pulmonary-artery tap and right ventricular heave, which were thought to be due to her thin body build. The remainder of the examination showed no abnormalities. The temperature increased to 38.5°C and the pulse to 113 beats per minute, and the blood pressure dropped to 84/48 mm Hg. The serum lactate dehydrogenase level was 457 U per liter; the levels of electrolytes, the results of tests of renal and liver function, and the results of other routine laboratory tests and urinalysis were normal. The hematocrit was 32.3 percent, the level of hemoglobin 10.9 g per deciliter, and the mean corpuscular volume 90 fl. Ceftriaxone (1 g) and fluids were given intravenously, and metronidazole (500 mg), azithromycin (500 mg), and acetaminophen were given orally. On the second and third hospital days, the patient had fatigue, fever as high as 38.8°C, and intermittent hypotension to 78/50 mm Hg. The hematocrit fell to 25.3 percent and then to 24.6 percent. One unit of packed red cells was transfused, and boluses of fluid were administered intravenously. The antibiotic agents were changed to ceftriaxone and clindamycin, and multiple specimens of blood and sputum were sent for culture. On the fourth hospital day, a diagnostic procedure was performed. Differential Diagnosis Dr. Margaret A. Shipp: In summary, this 30-year-old woman had increasingly severe symptoms of cough, hemoptysis, and chest pain, with fever, hypotension, and an elevated serum lactate dehydrogenase level. The most pertinent radiographic finding is a large anterior mediastinal mass encasing the left pulmonary vein. Although I am aware of the diagnosis in this case, it presents an opportunity to discuss the differential diagnosis of a mediastinal mass in a young woman. The anterior mediastinal compartment, which is located anterior to the pericardium, contains the thymus, lymphatic tissue, great veins, and the extrapericardial aorta and its branches.1 Anterior mediastinal masses are often malignant; the most common tumors are thymomas, germ-cell tumors, and lymphomas (Table 1).1 Table 1. Differential Diagnosis of an Anterior Mediastinal Mass. Thymomas occur with equal frequency in men and women, most often in adults from 30 to 50 years of age. More than half of thymomas are asymptomatic and are identified incidentally on imaging studies obtained for other reasons. Thymomas may also be found in patients with myasthenia gravis; invasive thymomas may be associated with cough or local discomfort. This patient is at the young end of the age spectrum for thymoma, and such rapid growth would be unusual. Germ-cell tumors that present as anterior mediastinal masses fall into two categories: benign teratomas and malignant germ-cell tumors. Benign teratomas occur with equal frequency in males and females from infancy through young adulthood. In contrast, malignant germ-cell tumors are most common in young men and are usually symptomatic. Malignant germ-cell tumors that are found as anterior mediastinal masses include both seminomas and nonseminomatous germ-cell tumors. Nonseminomatous germ-cell tumors are frequently associated with elevations in the levels of serum tumor markers, including the beta subunit of human chorionic gonadotropin, alpha-fetoprotein, or both. In this adult woman, primary mediastinal germ-cell tumor would be an unlikely diagnosis. Lymphomas that predominantly involve the anterior mediastinal masses include classic Hodgkin's lymphoma, precursor T-cell lymphoblastic lymphoma, and a recently identified subtype of large-B-cell lymphoma. Mediastinal Hodgkin's lymphoma is most frequently of the nodular-sclerosis type, which principally affects young adults, with a slight predominance in women. Precursor T-cell lymphoblastic lymphoma arises in the thymus, and is most common in adolescent and young adult men, although women and girls may be affected. The onset is usually acute, with symptoms resulting from compression of the airway and vessels by the mass; pleural and pericardial effusions are common; involvement of extrathoracic lymph nodes, peripheral blood, and bone marrow is common. During the past 20 years, a subtype of diffuse large-B-cell lymphoma has been identified, termed primary mediastinal large-B-cell lymphoma.2 It occurs in adolescents and young adults, with a median age in the fourth decade; women are affected twice as often as men, and they usually have no disease outside the mediastinum. Patients typically present with a bulky mediastinal mass with intrathoracic extension. Although they are unlikely to have additional systemic involvement at diagnosis, relapsed mediastinal large-B-cell lymphoma often involves unusual extranodal sites, such as the central nervous system, liver, adrenal glands, and kidneys (Table 2).2 Patients with mediastinal large-B-cell lymphoma, similar to those with diffuse large-B-cell lymphomas at other sites, often have an elevated level of serum lactate dehydrogenase. Table 2. Clinical and Genetic Features of Mediastinal Large-B-Cell Lymphoma. This patient's age and sex, the pace of progression of her symptoms, the presence of disease confined to the anterior mediastinum, and the elevated level of serum lactate dehydrogenase all argue in favor of a diagnosis of primary mediastinal large-B-cell lymphoma. Dr. Nancy Lee Harris: Dr. Hales, would you comment on your thoughts before the diagnostic procedure? Dr. Charles A. Hales (Pulmonary Medicine): The presence of cavitation within the lesion, as Dr. Aquino pointed out while discussing the CT scan, led us to consider tuberculosis, but there was no evidence of it. We ultimately also favored a diagnosis of lymphoma. Clinical Diagnosis Lymphoma. Dr. Margaret A. Shipp's Diagnosis Primary mediastinal large-B-cell lymphoma. Pathological Discussion Dr. Harris: The diagnostic procedure was a Chamberlain minithoracotomy, performed by Dr. Douglas Mathisen. The permanent sections show fine, compartmentalizing sclerosis with a dense cellular infiltrate (Figure 3A). At higher magnification, the cells have large, round, or irregular nuclei with dispersed chromatin, multiple nucleoli, and brisk mitotic activity (Figure 3B). These histologic features are typical of large-cell, non-Hodgkin's lymphoma, but the differential diagnosis includes nonlymphoid neoplasms. Immunoperoxidase staining showed that the neoplastic cells expressed the leukocyte common antigen (CD45) and the B-cell-associated marker (CD20) but did not express immunoglobulin light chains. A stain for Ki-67 showed a high proliferation fraction (>90 percent), and the cells were positive for the germinal-center marker Bcl-6, negative for CD10 and Bcl-2, and positive for the activation antigen CD30. These results confirm the diagnosis of diffuse large-B-cell lymphoma. The combination of clinical and pathologic features is diagnostic of primary mediastinal diffuse large-B-cell lymphoma. Figure 3. Biopsy Specimen of Mediastinal Mass (Hematoxylin and Eosin). A medium-power view (Panel A) shows fine, compartmentalizing sclerosis that causes a resemblance to an epithelial neoplasm. A high-magnification photomicrograph (Panel B) shows large, neoplastic cells, most with multiple nucleoli and some with pale-to-clear cytoplasm. Primary mediastinal diffuse large B-cell lymphoma was first described as an entity in the early 1980s.3,4 Before then — and even since then — it has often been misdiagnosed as a thymoma or a germ-cell tumor. With the advent of immunophenotyping studies, the tumor was identified as a large-B-cell lymphoma. Such tumors typically are composed of cells that resemble centroblasts (large germinal-center cells); rare cases may have larger cells with abundant cytoplasm and prominent nucleoli, resembling Reed–Sternberg cells and giving rise to a differential diagnosis with Hodgkin's lymphoma.5 The cytoplasm is often described as pale or clear and there is typically fine compartmentalizing sclerosis, as in this case, which may cause a resemblance to an epithelial malignancy.6,7 The tumor cells express B-cell-associated antigens, but 70 percent of the cases are negative for immunoglobulin, as this case was, although immunoglobulin genes are rearranged.8 Most cases express the antigen Bcl-6, associated with the germinal center; 25 to 30 percent are positive for CD10, another antigen associated with the germinal center; and a variable proportion express Bcl-2, the antiapoptosis protein, and CD30, a marker associated with Reed–Sternberg cells.9 Recently, expression of the MAL gene, which is associated with T-cell development, and the interleukin-4-induced gene 110 have been shown to be characteristic of primary mediastinal large-B-cell lymphoma. These markers are not available for clinical use, but they suggest that these tumors do have unique biologic features. The tumor cells have characteristic genetic features, including mutated class-switched immunoglobulin genes without evidence of ongoing somatic hypermutation11 (Table 2). The most frequent genetic abnormalities are gains in chromosomes 2p and 9p, including gains at the JAK2 9p24 and REL 2p16 loci.12,13 In contrast to diffuse large-B-cell lymphomas, primary mediastinal large-B-cell lymphomas rarely have either BCL2 rearrangements or translocations involving BCL6.14 Primary mediastinal large-B-cell lymphoma, despite the fact that it is a B-cell neoplasm, appears to arise in the thymus, a site of T-cell differentiation. At least two cases reported in the literature have been completely confined to the thymus without evidence of lymph-node involvement.7 Although the thymus is the site of antigen-independent T-cell differentiation, a few B cells are found in the normal thymic medulla; these cells are described as asteroid cells, which have an immunophenotype similar to that of those found in mediastinal diffuse large-B-cell lymphoma.15,16 There are two important points to make with regard to this entity. First, the morphologic and immunophenotypic features are not specific and can be found in diffuse large-B-cell lymphomas of other sites. Therefore, the pathologist needs to know the key clinical feature — that is, that the mass is located in the mediastinum — in order to make the correct diagnosis. Since diagnostic biopsy specimens may come from pulmonary extensions or supraclavicular extensions of the tumor, the primary site may not always be obvious from the pathology requisition. Second, there is morphologic and immunophenotypic overlap with Hodgkin's lymphoma of the nodular sclerosis type.5 Some cases have anaplastic or bizarre morphologic features with abundant cytoplasm and prominent nucleoli, and together with the CD30 expression this can give rise to a differential diagnosis of a lymphocyte-depleted variant of Hodgkin's lymphoma. Cases may also express CD15, a marker associated with Hodgkin's lymphoma, and such cases have been considered to represent a gray zone between diffuse large-B-cell lymphoma and classic Hodgkin's lymphoma.5 Discussion of Management Dr. Aquino: A gallium scan performed for staging showed intense uptake in the mediastinum that corresponds to the mass. There was no increased uptake in the pulmonary parenchyma and the remaining body uptake was normal. Dr. Shipp: Patients with mediastinal large-B-cell lymphoma are currently treated with a regimen that is similar to that used for patients with diffuse large B-cell lymphoma of other sites, with a doxorubicin-containing combination chemotherapy regimen. On the basis of findings in randomized cooperative group trials that indicated that more complicated chemotherapy regimens are no more effective than the cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) combination, patients with mediastinal large-B-cell lymphoma and diffuse large-B-cell lymphoma usually receive CHOP therapy or similar treatment.17 Studies suggest that adding the B-cell-specific CD20 monoclonal antibody (rituximab) to CHOP induction therapy improves both event-free and overall survival in patients with large-B-cell lymphomas.18 Patients with mediastinal large-B-cell lymphoma with bulky mediastinal disease often receive additional directed radiotherapy after they complete their induction chemotherapy.17 For these reasons, my recommendation for the patient under discussion would be six cycles of CHOP with rituximab followed by radiotherapy to the mediastinal mass. Analyses of patients with primary mediastinal large-B-cell lymphoma treated before the advent of rituximab use suggest that the treatment has an overall failure rate of approximately 40 percent.17 Clinical prognostic factor classification systems, such as the International Prognostic Index (IPI), are often used to predict the response of diffuse large-B-cell lymphoma to standard combination chemotherapy.19 The clinical features used to define a patient's IPI risk group (low, low-intermediate, high-intermediate, or high risk) include age at diagnosis, stage of disease, level of serum lactate dehydrogenase, performance status, and numbers of extranodal disease sites. The patient under discussion has an elevated level of lactate dehydrogenase and a nonambulatory performance status, which would place her in the low-intermediate risk group or higher. However, even patients who are successfully treated for primary mediastinal large-B-cell lymphoma remain at risk for long-term side effects. These side effects include an increased risk of breast cancer in the radiation field, cardiac dysfunction, and coronary artery disease, as well as therapy-related acute myeloid leukemias. For these reasons, additional information regarding the genetic features of primary mediastinal large-B-cell lymphoma that might help in the development of rational therapeutic targets would be extremely useful. To this end, we and others have compared the gene-expression profiles of primary mediastinal large-B-cell lymphoma with those of diffuse large-B-cell lymphoma of other sites.20,21 We found more than 2000 genes that were differentially expressed.20 The mediastinal large-B-cell lymphoma transcriptional signature included several genes previously reported to be expressed at high levels in this disease: the cell-surface protein and lipid-raft component, MAL; and the recently described interleukin-4-induced gene. There were also striking similarities to the expression profile of classic Hodgkin's lymphoma. Like Reed–Sternberg cells, cells in mediastinal large-B-cell lymphoma had low levels of expression of multiple B-cell signaling components and coreceptors and high levels of expression of cytokine pathway components, tumor necrosis factor (TNF) family members, and extracellular matrix elements (Table 3).5,20 Table 3. Genes with Increased Expression in Mediastinal Large-B-Cell Lymphoma. These observations are of particular interest because mediastinal large-B-cell lymphoma and the most common subtype of classic Hodgkin's lymphoma, nodular sclerosis, have similar clinical presentations: young patients, often women, with localized mediastinal tumors (Table 4). In both mediastinal large-B-cell lymphoma and classic Hodgkin's lymphoma, there is a prominent fibrotic component, and the malignant B cells have decreased expression of immunoglobulin and major-histocompatibility-complex molecules. Both tumors have amplifications of chromosomes 2p and 9p.13,22,23,24 Finally, these two entities may coexist in some patients.5 Table 4. Similarities between Mediastinal Large-B-Cell Lymphoma and Nodular Sclerosis Hodgkin's Lymphoma. Because the pathological distinction of primary mediastinal large-B-cell lymphoma from other diffuse large-B-cell lymphomas is difficult, we also assessed the possibility that components of the mediastinal large-B-cell lymphoma transcriptional signature might be useful immunohistochemical markers. We looked at TNF-receptor–associated factor 1 (TRAF-1) because of its roles in interleukin-13 signaling and TNF-mediated nuclear factor-B activation and the known expression of TRAF-1 in classic Hodgkin's lymphoma.25,26,27 In immunohistochemical staining, tumor cells of mediastinal large-B-cell lymphoma expressed TRAF-1, whereas cells from diffuse large-B-cell lymphomas lacked this marker.20 In classic Hodgkin's lymphoma, activation of the nuclear factor-B pathway is known to enhance the survival of Reed–Sternberg cells.28 Most cases of primary mediastinal large-B-cell lymphoma exhibit nuclear localization of the nuclear factor-B heterodimer, a feature consistent with activation of the nuclear factor-B pathway.20 These observations taken together suggest that there may be a shared survival pathway in mediastinal large-B-cell lymphoma and classic Hodgkin's lymphoma. The shared features of mediastinal large-B-cell lymphoma and classic Hodgkin's lymphoma have several therapeutic implications. In both bulky, localized classic Hodgkin's lymphoma and primary mediastinal large-B-cell lymphoma, we irradiate the primary disease site after induction chemotherapy. In the future, we may want to revisit the ideal chemotherapy regimen for primary mediastinal large-B-cell lymphoma and consider agents with proven efficacy in classic Hodgkin's lymphoma. Furthermore, the molecular signature of mediastinal large-B-cell lymphoma suggests additional possible rational therapeutic targets, including the nuclear factor-B pathway and other signaling pathways shared by classic Hodgkin's lymphoma and mediastinal large-B-cell lymphoma.20 Dr. Harris: Dr. Beroukhim, can you tell us about the treatment of this patient and her current status? Dr. Beroukhim: The patient received six cycles of CHOP chemotherapy with rituximab, which was complicated only by an episode of aseptic meningitis. She then received involved-field radiotherapy to the mediastinum, and is currently in complete remission, 2 years and 5 months after the diagnosis and 18 months after the completion of therapy. Anatomical Diagnosis Primary mediastinal diffuse large-B-cell lymphoma. Dr. Shipp reports receiving consulting fees or lecture fees from Corixa, Millenium Pharmaceuticals, and Eli Lilly. Source Information From the Division of Medical Oncology, Dana–Farber Cancer Institute (M.A.S.); the Departments of Radiology (S.L.A.) and Pathology (N.L.H.), Massachusetts General Hospital; and the Departments of Medicine (M.A.S.), Radiology (S.L.A.), and Pathology (N.L.H.), Harvard Medical School. References Cohen W. Anterior mediastinal mass lesions. 2004. (Accessed March 30, 2005, at http://www.uptodate.com) Barth TF, Leithauser F, Joos S, Bentz M, Moller P. Mediastinal (thymic) large B-cell lymphoma: where do we stand? Lancet Oncol 2002;3:229-234. Lichtenstein AK, Levine A, Taylor CR, et al. Primary mediastinal lymphoma in adults. Am J Med 1980;68:509-514. Levitt LJ, Aisenberg AC, Harris NL, Linggood RM, Poppema S. Primary non-Hodgkin's lymphoma of the mediastinum. Cancer 1982;50:2486-2492. Rudiger T, Jaffe ES, Delsol G, et al. Workshop report on Hodgkin's disease and related diseases (`grey zone' lymphoma). Ann Oncol 1998;9:Suppl 5:S31-S38. Moller P, Moldenhauer G, Momburg F, et al. Mediastinal lymphoma of clear cell type is a tumor corresponding to terminal steps of B cell differentiation. Blood 1987;69:1087-1095. Lamarre L, Jacobson JO, Aisenberg AC, Harris NL. Primary large cell lymphoma of the mediastinum: a histologic and immunophenotypic study of 29 cases. Am J Surg Pathol 1989;13:730-739. Scarpa A, Bonetti F, Menestrina F. Mediastinal large-cell lymphoma with sclerosis: genotypic analysis establishes its B nature. Virchows Arch A Pathol Anat Histopathol 1987;412:17-21. de Leval L, Ferry JA, Falini B, Shipp M, Harris NL. Expression of bcl-6 and CD10 in primary mediastinal large B-cell lymphoma: evidence for derivation from germinal center B cells? Am J Surg Pathol 2001;25:1277-1282. Copie-Bergman C, Gaulard P, Maouche-Chretien L, et al. The MAL gene is expressed in primary mediastinal large B-cell lymphoma. Blood 1999;94:3567-3575. Leithauser F, Bauerle M, Huynh MQ, Moller P. Isotype-switched immunoglobulin genes with a high load of somatic hypermutation and lack of ongoing mutational activity are prevalent in mediastinal B-cell lymphoma. Blood 2001;98:2762-2770. Bentz M, Barth TF, Bruderlein S, et al. Gain of chromosome arm 9p is characteristic of primary mediastinal B-cell lymphoma (MBL): comprehensive molecular cytogenetic analysis and presentation of a novel MBL cell line. Genes Chromosomes Cancer 2001;30:393-401. Joos S, Otano-Joos MI, Ziegler S, et al. Primary mediastinal (thymic) B-cell lymphoma is characterized by gains of chromosomal material including 9p and amplification of the REL gene. Blood 1996;87:1571-1578. Tsang P, Cesarman E, Chadburn A, Liu YF, Knowles DM. Molecular characterization of primary mediastinal B cell lymphoma. Am J Pathol 1996;148:2017-2025. Addis BJ, Isaacson PG. Large cell lymphoma of the mediastinum: a B-cell tumour of probable thymic origin. Histopathology 1986;10:379-390. Hofmann WJ, Momburg F, Moller P, Otto HF. Intra- and extrathymic B cells in physiologic and pathologic conditions: immunohistochemical study on normal thymus and lymphofollicular hyperplasia of the thymus. Virchows Arch A Pathol Anat Histopathol 1988;412:431-442. van Besien K, Kelta M, Bahaguna P. Primary mediastinal B-cell lymphoma: a review of pathology and management. J Clin Oncol 2001;19:1855-1864. Coiffier B, Lepage E, Brière J, et al. CHOP chemotherapy plus rituximab compared with CHOP alone in elderly patients with diffuse large-B-cell lymphoma. N Engl J Med 2002;346:235-242. The International Non-Hodgkin's Lymphoma Prognostic Factors Project. A predictive model for aggressive non-Hodgkin's lymphoma. N Engl J Med 1993;329:987-994. Savage KJ, Monti S, Kutok JL, et al. The molecular signature of mediastinal large B-cell lymphoma differs from that of other diffuse large B-cell lymphomas and shares features with classical Hodgkin lymphoma. Blood 2003;102:3871-3879. Rosenwald A, Wright G, Leroy K, et al. Molecular diagnosis of primary mediastinal B cell lymphoma identifies a clinically favorable subgroup of diffuse large B cell lymphoma related to Hodgkin lymphoma. J Exp Med 2003;198:851-862. Joos S, Granzow M, Holtgreve-Grez H, et al. Hodgkin's lymphoma cell lines are characterized by frequent aberrations on chromosomes 2p and 9p including REL and JAK2. Int J Cancer 2003;103:489-495. Barth TF, Martin-Subero JI, Joos S, et al. Gains of 2p involving the REL locus correlate with nuclear c-Rel protein accumulation in neoplastic cells of classical Hodgkin lymphoma. Blood 2003;101:3681-3686. Martin-Subero JI, Gesk S, Harder L, et al. Recurrent involvement of the REL and BCL11A loci in classical Hodgkin lymphoma. Blood 2002;99:1474-1477. Roy B, Bhattacharjee A, Xu B, Ford D, Maizel AL, Cathcart MK. IL-13 signal transduction in human monocytes: phosphorylation of receptor components, association with Jaks, and phosphorylation/activation of Stats. J Leukoc Biol 2002;72:580-589. Bradley JR, Pober JS. Tumor necrosis factor receptor-associated factors (TRAFs). Oncogene 2001;20:6482-6491. Durkop H, Foss HD, Demel G, Klotzbach H, Hahn C, Stein H. Tumor necrosis factor receptor-associated factor 1 is overexpressed in Reed-Sternberg cells of Hodgkin's disease and Epstein-Barr virus-transformed lymphoid cells. Blood 1999;93:617-623. Kuppers R, Schwering I, Brauninger A, Rajewsky K, Hansmann ML. Biology of Hodgkin's lymphoma. Ann Oncol 2002;13:Suppl 1:11-18....查看详细 (31349字节)
☉ 11325841:Disseminated Gonococcal Infection
A 23-year-old woman with a one-week history of swelling and pain in her right third finger (Panel A, arrow) was seen by an orthopedist, who prescribed cephalexin and indomethacin for suspected tenosynovitis. Over the next several days, a painful rash developed on the patient's extremities. She presented to the emergency department the day after pain developed in her right ankle with generalized malaise. Physical examination showed a temperature of 39.4°C (103°F) and a rash (Panels B and C) that was composed of both macular lesions (arrows) and pustular lesions (arrowheads). A complete blood count showed a leukocyte count of 31,000 cells per cubic millimeter. The patient reported having had unprotected sexual intercourse during the previous three weeks. A cervical culture was positive for Neisseria gonorrhoeae. The patient's symptoms and rash resolved within three days after treatment with intravenous ceftriaxone. Stephan Russ, M.D. Keith Wrenn, M.D. Vanderbilt University Medical Center Nashville, TN 37232...查看详细 (1046字节)
☉ 11325842:Stevens–Johnson Syndrome
A 22-year-old woman with a history of a seizure disorder presented to the emergency department after having a rash for three days and a fever for one day. The rash began as a maculopapular distribution on the neck and chest and rapidly progressed to target lesions and bullae (Panels A and B) that involved all surfaces of the integument and spared only the scalp. The patient had fevers as high as 40.5°C and painful erosions of the mucosa of the conjunctiva, mouth, and vagina. Since approximately 10 percent of her body surface was involved, a diagnosis of Stevens–Johnson syndrome was made. Five weeks before the development of the rash, the patient had been started on a gradually increasing dose of lamotrigine while therapy with valproate was tapered off. Serum concentrations of lamotrigine are markedly increased when this agent is taken with valproate, owing to an inhibition of lamotrigine metabolism. Both anticonvulsants were discontinued, and the patient received supportive care. In one study, a severe rash requiring hospitalization developed in 0.3 percent of patients receiving lamotrigine. Since the patient had not had a seizure in more than a decade, she was discharged with no anticonvulsant medication and has been free of seizures for more than a year. Jordan D. Fein, M.D. Kendal L. Hamann, M.D. University of California, Davis, Medical Center Sacramento, CA 95817...查看详细 (1415字节)
☉ 11325843:Inflammation, Atherosclerosis, and Coronary Artery Disease
Recent research has shown that inflammation plays a key role in coronary artery disease (CAD) and other manifestations of atherosclerosis. Immune cells dominate early atherosclerotic lesions, their effector molecules accelerate progression of the lesions, and activation of inflammation can elicit acute coronary syndromes. This review highlights the role of inflammation in the pathogenesis of atherosclerotic CAD. It will recount the evidence that atherosclerosis, the main cause of CAD, is an inflammatory disease in which immune mechanisms interact with metabolic risk factors to initiate, propagate, and activate lesions in the arterial tree. A decade ago, the treatment of hypercholesterolemia and hypertension was expected to eliminate CAD by the end of the 20th century. Lately, however, that optimistic prediction has needed revision. Cardiovascular diseases are expected to be the main cause of death globally within the next 15 years owing to a rapidly increasing prevalence in developing countries and eastern Europe and the rising incidence of obesity and diabetes in the Western world.1 Cardiovascular diseases cause 38 percent of all deaths in North America and are the most common cause of death in European men under 65 years of age and the second most common cause in women. These facts force us to revisit cardiovascular disease and consider new strategies for prediction, prevention, and treatment. Main Features of Atherosclerotic Lesions Atherosclerotic lesions (atheromata) are asymmetric focal thickenings of the innermost layer of the artery, the intima (Figure 1). They consist of cells, connective-tissue elements, lipids, and debris.2 Blood-borne inflammatory and immune cells constitute an important part of an atheroma, the remainder being vascular endothelial and smooth-muscle cells. The atheroma is preceded by a fatty streak, an accumulation of lipid-laden cells beneath the endothelium.3 Most of these cells in the fatty streak are macrophages, together with some T cells. Fatty streaks are prevalent in young people, never cause symptoms, and may progress to atheromata or eventually disappear. Figure 1. Atherosclerotic Lesion in a Human Artery. Panel A shows a cross-sectioned coronary artery from a patient who died of a massive myocardial infarction. It contains an occlusive thrombus superimposed on a lipid-rich atherosclerotic plaque. The fibrous cap covering the lipid-rich core has ruptured (area between the arrows), exposing the thrombogenic core to the blood. Trichrome stain was used, rendering luminal thrombus and intraplaque hemorrhage red and collagen blue. Panel B is a high-power micrograph of the area in Panel A indicated by the asterisk and shows that the contents of the atheromatous plaque have seeped through the gap in the cap into the lumen, suggesting that plaque rupture preceded thrombosis (the asterisk indicates cholesterol crystals). (Panels A and B courtesy of Dr. Erling Falk, University of Aarhus, Aarhus, Denmark.) Panel C illustrates the consequences of the activation of immune cells in a coronary plaque. Microbes, autoantigens, and various inflammatory molecules can activate T cells, macrophages, and mast cells, leading to the secretion of inflammatory cytokines (e.g., interferon- and tumor necrosis factor) that reduce the stability of plaque. The activation of macrophages and mast cells also causes the release of metalloproteinases and cysteine proteases, which directly attack collagen and other components of the tissue matrix. These cells may also produce prothrombotic and procoagulant factors that directly precipitate the formation of thrombus at the site of plaque rupture. In the center of an atheroma, foam cells and extracellular lipid droplets form a core region, which is surrounded by a cap of smooth-muscle cells and a collagen-rich matrix. T cells, macrophages, and mast cells infiltrate the lesion and are particularly abundant in the shoulder region where the atheroma grows.2,4,5 Many of the immune cells exhibit signs of activation and produce inflammatory cytokines.5,6,7,8 Myocardial infarction occurs when the atheromatous process prevents blood flow through the coronary artery. It was previously thought that progressive luminal narrowing from continued growth of smooth-muscle cells in the plaque was the main cause of infarction. Angiographic studies have, however, identified culprit lesions that do not cause marked stenosis,9 and it is now evident that the activation of plaque rather than stenosis precipitates ischemia and infarction (Figure 1). Coronary spasm may be involved to some extent, but most cases of infarction are due to the formation of an occluding thrombus on the surface of the plaque.10 There are two major causes of coronary thrombosis: plaque rupture and endothelial erosion. Plaque rupture, which is detectable in 60 to 70 percent of cases,11 is dangerous because it exposes prothrombotic material from the core of the plaque — phospholipids, tissue factor, and platelet-adhesive matrix molecules — to the blood (Figure 1). Ruptures preferentially occur where the fibrous cap is thin and partly destroyed. At these sites, activated immune cells are abundant.7 They produce numerous inflammatory molecules and proteolytic enzymes that can weaken the cap and activate cells in the core, transforming the stable plaque into a vulnerable, unstable structure that can rupture, induce a thrombus, and elicit an acute coronary syndrome (Figure 1). To understand how this can happen, we need to identify the key steps leading from a normal artery wall to a rupture-prone atherosclerotic plaque. Evolution of the Rupture-Prone Atherosclerotic Plaque Gene-Targeted Mouse Models Clinical investigations, population studies, and cell-culture experiments have provided important clues to the pathogenesis of atherosclerosis. However, experiments in animals are needed to dissect the pathogenetic steps and determine causality.12 Atherosclerosis does not develop in laboratory mice under normal conditions. However, targeted deletion of the gene for apolipoprotein E (apoE-knockout mice) leads to severe hypercholesterolemia and spontaneous atherosclerosis. Atherosclerosis also develops in mice lacking low-density lipoprotein (LDL) receptors, especially when the mice are fed a fatty diet. One can use these knockout mice to study the relationship between hypercholesterolemia and atherosclerosis and to assess the effects of other genes and gene products on these conditions. By mating these mice with knockout mice lacking immunoregulatory genes, it is possible to clarify the role of immunologic and inflammatory mechanisms in atherosclerosis. Obviously, the findings in such models must be corroborated, as much as possible, by studies of human cells and tissues. Our current understanding of atherosclerosis therefore rests on a combination of research in animals and cell cultures, analysis of human lesions, clinical investigations of patients with acute coronary syndromes, and epidemiologic studies of CAD. Lipoprotein Retention and Activation of Immune Cells Role of Endothelial Activation, Adhesion Molecules, and Chemokines Studies in animals and humans have shown that hypercholesterolemia causes focal activation of endothelium in large and medium-sized arteries. The infiltration and retention of LDL in the arterial intima initiate an inflammatory response in the artery wall13,14 (Figure 2). Modification of LDL, through oxidation or enzymatic attack in the intima, leads to the release of phospholipids that can activate endothelial cells,14 preferentially at sites of hemodynamic strain.15 Patterns of hemodynamic flow typical for atherosclerosis-prone segments (low average shear but high oscillatory shear stress) cause increased expression of adhesion molecules and inflammatory genes by endothelial cells.16 Therefore, hemodynamic strain and the accumulation of lipids may initiate an inflammatory process in the artery. Figure 2. Activating Effect of LDL Infiltration on Inflammation in the Artery. In patients with hypercholesterolemia, excess LDL infiltrates the artery and is retained in the intima, particularly at sites of hemodynamic strain. Oxidative and enzymatic modifications lead to the release of inflammatory lipids that induce endothelial cells to express leukocyte adhesion molecules. The modified LDL particles are taken up by scavenger receptors of macrophages, which evolve into foam cells. The platelet is the first blood cell to arrive at the scene of endothelial activation.17 Its glycoproteins Ib and IIb/IIIa engage surface molecules on the endothelial cell, which may contribute to endothelial activation. Inhibition of platelet adhesion reduces leukocyte infiltration and atherosclerosis in hypercholesterolemic mice.17 Activated endothelial cells express several types of leukocyte adhesion molecules, which cause blood cells rolling along the vascular surface to adhere at the site of activation.18 Since vascular-cell adhesion molecule 1 (VCAM-1) is typically up-regulated in response to hypercholesterolemia, cells carrying counterreceptors for VCAM-1 (i.e., monocytes and lymphocytes) preferentially adhere to these sites (Figure 2, Figure 3, and Figure 4).19 Once the blood cells have attached, chemokines produced in the underlying intima stimulate them to migrate through the interendothelial junctions and into the subendothelial space (Figure 2, Figure 3, and Figure 4). Genetic abrogation or pharmacologic blockade of certain chemokines and adhesion molecules for mononuclear cells inhibits atherosclerosis in mice.20,21,22,23,24 Figure 3. Role of Macrophage Inflammation of the Artery. Monocytes recruited through the activated endothelium differentiate into macrophages. Several endogenous and microbial molecules can ligate pattern-recognition receptors (toll-like receptors) on these cells, inducing activation and leading to the release of inflammatory cytokines, chemokines, oxygen and nitrogen radicals, and other inflammatory molecules and, ultimately, to inflammation and tissue damage. Figure 4. Effects of T-Cell Activation on Plaque Inflammation. Antigens presented by macrophages and dendritic cells (antigen-presenting cells) trigger the activation of antigen-specific T cells in the artery. Most of the activated T cells produce Th1 cytokines (e.g., interferon-), which activate macrophages and vascular cells, leading to inflammation. Regulatory T cells modulate the process by secreting antiinflammatory cytokines (such as interleukin-10 and transforming growth factor ). Macrophages in the Developing Plaque A cytokine or growth factor produced in the inflamed intima, macrophage colony-stimulating factor, induces monocytes entering the plaque to differentiate into macrophages (Figure 3). This step is critical for the development of atherosclerosis25 and is associated with up-regulation of pattern-recognition receptors for innate immunity, including scavenger receptors and toll-like receptors.26,27 Scavenger receptors internalize a broad range of molecules and particles bearing molecules with pathogen-like molecular patterns.26 Bacterial endotoxins, apoptotic cell fragments, and oxidized LDL particles are all taken up and destroyed through this pathway. If cholesterol derived from the uptake of oxidized LDL particles cannot be mobilized from the cell to a sufficient extent, it accumulates as cytosolic droplets. Ultimately, the cell is transformed into a foam cell, the prototypical cell in atherosclerosis. Toll-like receptors also bind molecules with pathogen-like molecular patterns, but in contrast to scavenger receptors, they can initiate a signal cascade that leads to cell activation.27 The activated macrophage produces inflammatory cytokines, proteases, and cytotoxic oxygen and nitrogen radical molecules. Similar effects are observed in dendritic cells, mast cells, and endothelial cells, which also express toll-like receptors. Bacterial toxins, stress proteins, and DNA motifs are all recognized by various toll-like receptors.27 In addition, human heat-shock protein 60 and oxidized LDL particles may activate these receptors.28,29 Cells in human atherosclerotic lesions display a spectrum of toll-like receptors,30 and plaque inflammation may partly depend on this pathway. In support of this notion, genetic removal of a molecule in the toll-like receptor signaling pathway inhibits atherosclerosis in apoE-knockout mice.31 T-Cell Activation and Vascular Inflammation Immune cells, including T cells, antigen-presenting dendritic cells, monocytes, macrophages, and mast cells, patrol various tissues, including atherosclerotic arteries, in search of antigen.32,33 A T-cell infiltrate is always present in atherosclerotic lesions (Figure 4). Such infiltrates are predominantly CD4+ T cells, which recognize protein antigens presented to them as fragments bound to major-histocompatibility-complex (MHC) class II molecules (Figure 4). CD4+ T cells reactive to the disease-related antigens oxidized LDL, heat-shock protein 60, and chlamydia proteins have been cloned from human lesions.28,34,35 A minor T-cell subpopulation, natural killer T cells, is prevalent in early lesions. Natural killer T cells recognize lipid antigens, and their activation increases atherosclerosis in apoE-knockout mice.36 CD8+ T cells restricted by MHC class I antigens are also present in atherosclerotic lesions.33 These cells typically recognize viral antigens, which may be present in the lesions (see below). Activation of CD8+ T cells in apoE-knockout mice can cause the death of arterial cells and accelerate atherosclerosis.37 When the antigen receptor of the T cell is ligated by antigen, an activation cascade results in the expression of a set of cytokines, cell-surface molecules, and enzymes. In inbred mice, two stereotypical responses can be elicited.38 The type 1 helper T (Th1) response activates macrophages, initiates an inflammatory response similar to delayed hypersensitivity, and characteristically functions in the defense against intracellular pathogens. The type 2 helper T (Th2) response elicits an allergic inflammation. Although the Th1–Th2 system is more plastic in humans, the general pattern is similar. The atherosclerotic lesion contains cytokines that promote a Th1 response (rather than a Th2 response).8,39 Activated T cells therefore differentiate into Th1 effector cells and begin producing the macrophage-activating cytokine interferon- (Figure 4). Interferon- improves the efficiency of antigen presentation and augments synthesis of the inflammatory cytokines tumor necrosis factor and interleukin-1.38 Acting synergistically, these cytokines instigate the production of many inflammatory and cytotoxic molecules in macrophages and vascular cells.33 All these actions tend to promote atherosclerosis. Indeed, in apoE-knockout mice lacking interferon- or its receptor, the development of atherosclerosis is inhibited.40,41 Similarly, the extent of the disease is reduced when the Th1 pathway is inhibited pharmacologically42 or genetically43,44,45 in animals. Cytokines of the Th2 pathway can promote antiatherosclerotic immune reactions.46 However, they may also contribute to the formation of aneurysms by inducing elastolytic enzymes.47 Therefore, switching the immune response of atherosclerosis from Th1 to Th2 may not necessarily lead to reduced vascular disease. T-cell cytokines cause the production of large amounts of molecules downstream in the cytokine cascade (Figure 5). As a result, elevated levels of interleukin-6 and C-reactive protein may be detected in the peripheral circulation. In this way, the activation of a limited number of immune cells can initiate a potent inflammatory cascade, both in the forming lesion and systemically. Figure 5. The Cytokine Cascade. Activated immune cells in the plaque produce inflammatory cytokines (interferon-, interleukin-1, and tumor necrosis factor ), which induce the production of substantial amounts of interleukin-6. These cytokines are also produced in various tissues in response to infection and in the adipose tissue of patients with the metabolic syndrome. Interleukin-6, in turn, stimulates the production of large amounts of acute-phase reactants, including C-reactive protein (CRP), serum amyloid A, and fibrinogen, especially in the liver. Although cytokines at all steps have important biologic effects, their amplification at each step of the cascade makes the measurement of downstream mediators such as CRP particularly useful for clinical diagnosis. Antiinflammatory Factors and Disease Activity Powerful regulators built into the immune network act as protective factors in atherosclerosis. They include two antiinflammatory cytokines, interleukin-10 and transforming growth factor (TGF-). Antibody responses and metabolic factors can also contribute to immune regulation. Gene targeting or pharmacologic inhibition of interleukin-10 aggravates atherosclerosis in hypercholesterolemic mice and exacerbates coronary thrombosis.48,49,50 Abrogation of TGF- signaling in T cells elicits a dramatic phenotype, with rapid development of large, unstable atherosclerotic lesions.51 These effects indicate that T-cell–mediated immunity is under tonic inhibition by TGF- and interleukin-10; removal of these brakes on atherosclerosis accelerates the process. Antibody-producing B cells, although not numerous in lesions, contribute to antiatherosclerotic activity, perhaps as a result of specific antibodies against plaque antigens, binding of antibodies to inhibitory Fc receptors, or cytokines produced by B cells. Spleen B cells are particularly effective inhibitors of atherosclerosis,52 possibly because certain natural antibodies produced by some of these cells recognize phosphorylcholine, a molecule present in oxidized LDL, apoptotic cell membranes, and the cell wall of Streptococcus pneumoniae.53 These antibodies may contribute to the elimination of oxidized LDL and dead cells as well as to the defense against pneumococcal infections. Interestingly, persons who have undergone splenectomy have increased susceptibility not only to pneumococcal infections but also to CAD.54 Cross-Talk between Inflammation and Metabolism The balance between inflammatory and antiinflammatory activity controls the progression of atherosclerosis. Metabolic factors may affect this process in several ways. Obviously, they contribute to lipid deposition in the artery, initiating new rounds of immune-cell recruitment. Furthermore, the adipose tissue of patients with the metabolic syndrome and obesity produces inflammatory cytokines, particularly tumor necrosis factor and interleukin-6 (Figure 5).55,56 "Adipokines" — cytokines of the adipose tissue, including leptin, adiponectin, and resistin — may also influence inflammatory responses throughout the organism.55 Finally, molecules generated during lipid peroxidation in atherosclerotic disease can induce protective as well as inflammatory reactions, for instance, by binding to nuclear receptors that control inflammatory genes.14,57 Infections and CAD Several studies have linked infections to atherosclerosis and CAD. Elevated titers of antibodies against chlamydia were found in patients with CAD,58 and it was speculated that this microbe causes atherosclerosis. However, Chlamydia pneumoniae infection does not cause atherosclerosis in animals, although it may stimulate disease progression and plaque activation.59,60 This could be due either to a direct action in plaques or to remote signaling by inflammatory mediators.61 Molecular mimicry between C. pneumoniae antigens and human molecules may contribute to the activation of inflammation.62 However, several recent secondary-prevention trials, including two reported in this issue of the Journal, failed to prevent acute coronary syndromes by administering antibiotics targeting C. pneumoniae, suggesting that C. pneumoniae infection is not a predominant cause of these syndromes.63,64,65,66 Herpes family viruses may also contribute to CAD. Cytomegalovirus is found in lesions, can modulate immune-cell as well as vascular-cell activity, and increases experimental atherosclerosis.67,68,69 Clinical data imply an important role for cytomegalovirus in transplantation-related arteriosclerosis causing graft rejection.70 More studies will be needed to determine whether the virus is involved in more common forms of CAD. Since several types of pathogens may contribute to CAD, it is unlikely that a single microbe causes atherosclerosis. Instead, the total burden of infection at various sites may affect the progression of atherosclerosis and elicit clinical manifestations.71 Acute Coronary Syndromes Mechanisms of Plaque Rupture What causes a silent atherosclerotic lesion to rupture? Activated macrophages, T cells, and mast cells at sites of plaque rupture5,7,72 produce several types of molecules — inflammatory cytokines, proteases, coagulation factors, radicals, and vasoactive molecules — that can destabilize lesions (Figure 1). They inhibit the formation of stable fibrous caps, attack collagen in the cap, and initiate thrombus formation.73,74,75,76 All these reactions can conceivably induce the activation and rupture of plaque, thrombosis, and ischemia. Two types of proteases have been implicated as key players in plaque activation: matrix metalloproteinases (MMPs) and cysteine proteases.77,78 Several members of these families of enzymes occur in the plaque and may degrade its matrix. MMP activity is controlled at several levels: inflammatory cytokines induce the expression of MMP genes, plasmin activates proforms of these enzymes, and inhibitor proteins (tissue inhibitor of metalloproteinase) suppress their action. Similarly, cysteine proteases are induced by certain cytokines and checked by inhibitors termed "cystatins."78 Several of these molecules play decisive roles in the formation of aneurysms, as shown by experiments in gene-targeted mice. However, mechanistic studies in models of atherosclerosis have yielded complex results, with certain MMPs reducing rather than increasing the size of the lesions. At the same time, these enzymes clearly affect the composition of plaque. Therefore, they may represent future therapeutic targets. Study of plaque rupture in animal models should be helpful in determining the role of these proteases in the activation of plaque and myocardial infarction. Systemic Indicators of Inflammation The inflammatory process in the atherosclerotic artery may lead to increased blood levels of inflammatory cytokines and other acute-phase reactants (Figure 5). Levels of C-reactive protein and interleukin-6 are elevated in patients with unstable angina and myocardial infarction, with high levels predicting worse prognosis.79,80,81 The levels of other inflammatory markers are also elevated in these patients, including fibrinogen, interleukin-7, interleukin-8, soluble CD40 ligand, and the C-reactive protein–related protein pentraxin 3.82,83,84,85 Levels of C-reactive protein are elevated in patients with unstable angina, a condition that is probably dependent on coronary thrombosis of atherosclerotic plaques, but not in those with variant angina caused by vasospasm.86 Therefore, elevated C-reactive protein levels in patients with acute coronary syndromes likely reflect inflammation in the coronary artery rather than in the ischemic myocardium.86 Activated T cells are also present and subgroups of inflammatory T cells are increased in the blood of patients with acute coronary syndromes.87,88 Collectively, these findings suggest that inflammatory immune activation in coronary arteries initiates acute coronary syndromes, with circulating levels of inflammatory markers reflecting the clinical course of the condition. Inflammatory Markers and the Risk of CAD Although the degree of active inflammation is increased in activated plaques of patients with acute coronary syndromes, smoldering inflammation characterizes silent plaques. Such lesions may also release inflammatory mediators into the systemic circulation (Figure 5). A moderately elevated C-reactive protein level on a highly sensitive immunoassay is an independent risk factor for CAD in a healthy population.89,90 Whether this test should be used to screen asymptomatic persons is a matter of debate.90 Other measures of acute-phase reactants, including the erythrocyte sedimentation rate and levels of fibrinogen and other plasma proteins, also provide information about the inflammatory risk of CAD,91 as do levels of circulating, soluble adhesion molecules such as soluble intercellular adhesion molecule 1, soluble VCAM-1, and soluble P-selectin, which are shed by activated cells.92 The fact that several different inflammatory markers, with different biologic activities, contribute to the statistical risk of CAD makes it unlikely that C-reactive protein or any of the other markers actually causes the disease. Instead, they all reflect the local inflammatory process in the artery and, perhaps, other tissues (e.g., adipose tissue) (Figure 5). Further research will be needed to clarify the role of these molecules as markers of risk as well as contributors to disease progression. Therapeutic Opportunities The knowledge that atherosclerosis is an inflammatory disease offers new opportunities for the prevention and treatment of CAD. Powerful immunosuppressant or antiinflammatory agents could represent attractive treatments for acute coronary syndromes.93 For long-term prevention of atherosclerosis, a more specific approach is desirable, such as vaccination with disease-related antigens.94 Experimental results in both these areas are encouraging. The immunosuppressive drugs cyclosporine and sirolimus block the activation of T cells and, at high levels, smooth-muscle proliferation.95 They inhibit intimal lesions,95,96 and sirolimus-coated stents are currently used to prevent restenosis after angioplasty.97 Whether this family of compounds can be used in acute coronary syndromes is not known. Antiinflammatory compounds include cyclooxygenase-2 inhibitors and other inhibitors of eicosanoid synthesis. The situation is complex, however, since enzymes inhibited by such compounds are also involved in the production of prothrombotic eicosanoids by platelets and endothelial synthesis of antithrombotic eicosanoids. The recent findings of an increased incidence of cardiovascular events in patients treated with the cyclooxygenase-2 inhibitor rofecoxib (Vioxx)98 demonstrate the complexity of eicosanoid biology and indicate the need for a cautious approach to the use of this type of antiinflammatory compounds in patients with cardiovascular disease. Remarkably, lipid-lowering statins have antiinflammatory properties.99,100,101 They are among the most important of the pleiotropic effects of statins (i.e., effects not directly dependent on reduced cholesterol levels). These properties likely result from the ability of statins to inhibit the formation of mevalonic acid. Downstream products of this molecule include not only the end product, cholesterol, but also several isoprenoid intermediates that are used by lipids to attach to several intracellular signaling molecules.99 The enzymatic addition of isoprenoids to intracellular proteins controls the activity of many signaling pathways, including those of cell division and antigen presentation. In addition, reduced cholesterol levels in membranes of cells exposed to statins may interfere with the clustering of T-cell–antigen receptors during immune activation.102 Several beneficial effects of statins may be due to antiinflammatory activity. For instance, atorvastatin ameliorates experimental autoimmune encephalomyelitis,103 and a recent clinical trial demonstrated that atorvastatin has beneficial effects in patients with rheumatoid arthritis.104 This may be due to the capacity of statins to inhibit antigen-dependent T-cell activation.105 Other important targets include endothelial nitric oxide production and fibrinolysis, both of which are enhanced by statins, and platelet activity, which is reduced.99 Inhibition of inflammation adds to lipid lowering as beneficial effects of statins on CAD, as recently demonstrated in two clinical trials of patients with atherosclerosis and CAD. In these studies, reduction of inflammation (reflected by C-reactive protein levels) through statin therapy improved the clinical outcome independently of the reduction in serum cholesterol levels.106,107 Finally, vaccination is an attractive approach to induce protective immunity.94 In experiments in animals, atherosclerosis was reduced by vaccination with oxidized LDL, bacteria containing certain modified phospholipids, or heat-shock protein 60.53,108,109,110,111,112 This may be due to the induction of protective antibodies or T cells. However, better antigen preparations must be developed and more mechanistic knowledge obtained before this approach can be tested in humans. In conclusion, new knowledge about inflammation in CAD has provided surprising insights into its pathogenesis, has offered new opportunities for diagnosis and prediction, and may lead to new treatments for this life-threatening disease. Supported by the Swedish Research Council and Heart–Lung Foundation, the European Union, the National Institutes of Health, and the S?derberg Foundation. I am indebted to Drs. P?l Aukrust, Petri Kovanen, Lars Rydén, and Lars Wallentin for their review of the manuscript and helpful suggestions; to Dr. Erling Falk for kindly providing Figure 1A and 1B; and to all the colleagues, fellows, students, and assistants who have studied inflammatory mechanisms in atherosclerosis with me. Source Information From the Karolinska Institute, Center for Molecular Medicine, Department of Medicine, Karolinska University Hospital, Stockholm. Address reprint requests to Dr. Hansson at the Center for Molecular Medicine, L8:03, Karolinska University Hospital, SE-17176 Stockholm, Sweden, or at goran.hansson@cmm.ki.se. References Murray CJ, Lopez AD. Global mortality, disability, and the contribution of risk factors: Global Burden of Disease Study. Lancet 1997;349:1436-1442. 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Danesh J, Wheeler JG, Hirschfield GM, et al. C-reactive protein and other circulating markers of inflammation in the prediction of coronary heart disease. N Engl J Med 2004;350:1387-1397. Engstr?m G, Hedblad B, Stavenow L, et al. Fatality of future coronary events is related to inflammation-sensitive plasma proteins: a population-based prospective cohort study. Circulation 2004;110:27-31. Blake GJ, Ridker PM. Inflammatory bio-markers and cardiovascular risk prediction. J Intern Med 2002;252:283-294. Libby P, Aikawa M. Stabilization of atherosclerotic plaques: new mechanisms and clinical targets. Nat Med 2002;8:1257-1262. Nilsson J, Hansson GK, Shah PK. Immunomodulation of atherosclerosis: implications for vaccine development. Arterioscler Thromb Vasc Biol 2005;25:18-28. Jonasson L, Holm J, Hansson GK. Cyclosporin A inhibits smooth muscle proliferation in the vascular response to injury. Proc Natl Acad Sci U S A 1988;85:2303-2306. Gallo R, Padurean A, Jayaraman T, et al. Inhibition of intimal thickening after balloon angioplasty in porcine coronary arteries by targeting regulators of the cell cycle. Circulation 1999;99:2164-2170. Marx SO, Marks AR. Bench to bedside: the development of rapamycin and its application to stent restenosis. Circulation 2001;104:852-855. Bresalier RS, Sandler RS, Quan H, et al. Cardiovascular events associated with rofecoxib in a colorectal adenoma chemoprevention trial. N Engl J Med 2005;352:1092-1102. Takemoto M, Liao JK. Pleiotropic effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Arterioscler Thromb Vasc Biol 2001;21:1712-1719. Crisby M, Nordin-Fredriksson G, Shah PK, Yano J, Zhu J, Nilsson J. Pravastatin treatment increases collagen content and decreases lipid content, inflammation, metalloproteinases, and cell death in human carotid plaques: implications for plaque stabilization. Circulation 2001;103:926-933. Sposito AC, Chapman MJ. Statin therapy in acute coronary syndromes: mechanistic insight into clinical benefit. Arterioscler Thromb Vasc Biol 2002;22:1524-1534. Ehrenstein MR, Jury EC, Mauri C. Statins for atherosclerosis -- as good as it gets? N Engl J Med 2005;352:73-75. Youssef S, Stuve O, Patarroyo JC, et al. The HMG-CoA reductase inhibitor, atorvastatin, promotes a Th2 bias and reverses paralysis in central nervous system autoimmune disease. Nature 2002;420:78-84. McCarey DW, McInnes IB, Madhok R, et al. Trial of Atorvastatin in Rheumatoid Arthritis (TARA): double-blind, randomised placebo-controlled trial. Lancet 2004;363:2015-2021. Kwak B, Mulhaupt F, Myit S, Mach F. Statins as a newly recognized type of immunomodulator. Nat Med 2000;6:1399-1402. Ridker PM, Cannon CP, Morrow D, et al. C-reactive protein levels and outcomes after statin therapy. N Engl J Med 2005;352:20-28. Nissen SE, Tuzcu EM, Schoenhagen P, et al. Statin therapy, LDL cholesterol, C-reactive protein, and coronary artery disease. N Engl J Med 2005;352:29-38. Palinski W, Miller E, Witztum JL. Immunization of low density lipoprotein (LDL) receptor-deficient rabbits with homologous malondialdehyde-modified LDL reduces atherogenesis. Proc Natl Acad Sci U S A 1995;92:821-825. Zhou X, Caligiuri G, Hamsten A, Lefvert AK, Hansson GK. LDL immunization induces T-cell-dependent antibody formation and protection against atherosclerosis. Arterioscler Thromb Vasc Biol 2001;21:108-114. Fredrikson GN, Soderberg I, Lindholm M, et al. Inhibition of atherosclerosis in apoE-null mice by immunization with apoB-100 peptide sequences. Arterioscler Thromb Vasc Biol 2003;23:879-884. Harats D, Yacov N, Gilburd B, Shoenfeld Y, George J. Oral tolerance with heat shock protein 65 attenuates Mycobacterium tuberculosis-induced and high-fat-diet-driven atherosclerotic lesions. J Am Coll Cardiol 2002;40:1333-1338. Maron R, Sukhova G, Faria AM, et al. Mucosal administration of heat shock protein-65 decreases atherosclerosis and inflammation in aortic arch of low-density lipoprotein receptor-deficient mice. Circulation 2002;106:1708-1715....查看详细 (50642字节)
☉ 11325844:Rehabilitation after Stroke
This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the author's clinical recommendations. A 66-year-old man was suddenly unable to speak, follow directions, or move his right arm and leg. He received tissue plasminogen activator within 90 minutes. Four days later, his speech was limited to effortful answers of yes or no. He could not walk or use his right arm, and self-care tasks required maximal assistance. What advice would you offer him and his family regarding rehabilitation for his disabilities? The Clinical Problem Approximately 400 persons per 100,000 population over the age of 45 years have a first stroke each year in the United States, Europe, and Australia. Stroke is the most frequent cause of adult-onset disability among people in the United States, and the cost of related care is among the fastest-growing expenses for Medicare.1 The likelihood of improvement after stroke varies with the nature and severity of the initial deficit. Approximately 35 percent of survivors with initial paralysis of the leg do not regain useful function, and 20 to 25 percent of all survivors are unable to walk without full physical assistance.2 Six months after stroke, about 65 percent of patients cannot incorporate the affected hand into their usual activities. Poor upper-extremity outcomes are probable after a hemispheric infarction when the leg cannot move by two weeks and the hand has no movement or only slight finger flexion with no opening by four weeks, consistent with considerable damage to the corticospinal tract.3 Patients who survive a stroke almost always have less physical disability by the end of the first three months. Functional scales, such as the Barthel Index and the Functional Independence Measure (which measure the physical assistance or supervision needed for self-care, including using the toilet, dressing, bathing, eating, and mobility), tend to show a plateau of gains by three to four months after stroke, partly owing to insensitivity of the scale to further improvements. Patients who no longer require assistance at that point may still be unable to use the affected hand, walk at speeds and distances that permit activities outside the home, or live alone. Only 25 percent of patients return to the level of everyday participation and physical functioning of community-matched persons who have not had a stroke.4 The quality of life tends to be higher among patients with better functioning than among those with worse functioning.5 Improvement especially during the first few weeks after a stroke reflects the recovery of neurotransmission in spared tissue near and remote from an infarct or hemorrhage.6,7 At any time after the stroke, however, cognitive, language, and motor skills may improve by means of the cerebral processes involved in ordinary learning. This experience-induced neuroplasticity includes greater excitability and recruitment of the neurons in both hemispheres of the brain that contribute to performance, sprouting of dendrites that communicate with other neurons, and strengthening of these synaptic connections. Functional neuroimaging studies have shown the evolution of cerebral activity within both hemispheres as patients' skills improve with training and experience.8 Strategies and Evidence Neurorehabilitation studies of patients who have had a stroke often have limitations, including heterogeneity of impairments and disabilities, poorly defined or controlled interventions, small differences in treatment time or type of treatment, lack of randomization or masking, inadequate samples, and insensitive outcome measures.9 In well-designed rehabilitation trials, the magnitude of improvement with the guidance of physical or occupational therapy tends to be modest but clinically useful, such as a 5-point increase in the Barthel Index (with a range of 0 to 15, with higher numbers indicating greater independence) or an increase in walking speed of 0.10 m per second.10 This article focuses on sound randomized trials and meta-analyses of rehabilitation strategies that are useful after hemiplegic stroke. Settings for Therapy Inpatient rehabilitation is recommended for patients who are too disabled to return home but who have adequate cognition and fitness to participate in therapy for three hours a day, who need ongoing supervision by nurses and physicians for medical care and education, and who have sufficient social support to return home (Figure 1).11 The most common disability that leads to referral to inpatient rehabilitation is the inability to walk safely without physical help. On the basis of Medicare coverage policies, the current median length of stay in an inpatient rehabilitation facility is only 16 days, so efficient services are essential.12 Approximately 80 percent of patients who undergo inpatient rehabilitation are discharged to their homes. Medicare pays for home-based rehabilitation services for the next few weeks after discharge, when patients are too disabled to travel, and then for treatment two to three times a week at an outpatient facility for a period of one to three months, until the patient reaches a plateau in terms of gains in activities of daily living. Figure 1. Algorithm for Placement for Rehabilitation Care after Stroke. Minimal assistance denotes physical help from another person that consists of no more than touching while the patient expends 75 percent of the effort (e.g., to walk, reach for an object, manage self-care); moderate assistance denotes physical help needed while the patient expends 50 to 75 percent of the effort; and maximal assistance denotes physical help needed while the patient expends less than 50 percent of the effort. The results of a meta-analysis indicate that care in an inpatient stroke unit that provides multidisciplinary services, coordinates disability-related medical care, and trains caregivers results in fewer deaths, less disability, and less need for institutionalization in nursing facilities, as compared with hospital care on general wards.13 Such care may enable an extra 5 patients of every 100 to return home.14 Randomized trials that compare inpatient rehabilitation with community-based care designed to permit earlier hospital discharge of patients who need only intermittent assistance generally find that caregivers have greater stress when these patients are discharged early, but that the functional outcomes among these patients are equal to those of patients receiving inpatient rehabilitation.15 Just four hours of rehabilitation training of motivated caregivers may improve their mood and quality of life and reduce short-term financial costs.16 Small trials support the benefit of training caregivers specifically to assist patients in safe swallowing, speech, and walking for exercise and in finding solutions for managing daily activities. Therapists can monitor and advance this home training. Coordinated direction of outpatient therapies, assistance in finding community resources such as transportation and support groups, and counseling about sexuality, nutrition, and exercise have been shown to improve the patients' skills in activities of daily living and participation in the community, as compared with patients who do not receive such coordinated services.17 Targeted Therapy Aphasia About 20 percent of patients have impaired expression and comprehension of language after a stroke and should receive speech therapy. The broad range of the types and severity of aphasia, as well as the diverse strategies used in its treatment, complicates the design of clinical trials. A meta-analysis of the diverse approaches used to treat all patients with aphasia after stroke showed a positive, moderate effect for treatment begun within the first 3 months after stroke, as compared with no treatment, as well as a smaller but positive effect when treatment was initiated between 3 to 12 months after stroke and even after more than 1 year.18 The results of trials may not reflect the small gains that benefit the patient and family, such as greater accuracy of yes and no responses, gestures or pointing to pictures to indicate needs, and suppression of repetitive babble. Patients treated by speech therapists perform better than those treated by trained volunteers.19 Greater intensity of treatment, ranging from 40 to 100 hours (5 hours or more weekly) of treatment targeted to specific impairments, correlates directly with the magnitude of improvement, primarily among patients whose stroke occurred less than six months previously.20,21,22 Improvements in targeted language impairments have been associated with changes in activity in the cortical regions of the brain associated with language skills.23,24 Self-Care and Functional Use of the Arm Significant benefit is most often achieved among patients with moderate levels of disability as measured on functional scales, but not among those with the greatest disability.25 For patients with hemiplegia, the initial functional training emphasizes compensatory strategies. For example, patients learn to transfer from a bed into a wheelchair for mobility, and self-care is performed with one-handed techniques with the use of the unaffected arm. Overnight splinting maintains wrist and finger extension but may not improve the range of motion in the affected hand or reduce pain.26 Recent trials emphasize the practice of task-related movements (Table 1). Many different task-oriented practice strategies have shown significantly greater benefit from more intensive therapies (16 or more additional hours of treatment) that involve training in specific skills,10,27 as compared with only several additional hours a week of general rehabilitation spread among many activities.28 Table 1. Strategies for Therapy That Clinicians Can Encourage after Hemiplegic Stroke. Initial interventions for the affected arm are aimed at eliciting small voluntary or reflexive involuntary movements. Training the arm for functional activities can start when the arm and hand begin to overcome gravity. If no hand dexterity is apparent by six weeks after stroke,3 further rehabilitation should emphasize maintaining a comfortably mobile arm. Protocols for constraint-induced–movement therapy are based on the theory that nonuse of an arm may result from the great effort required to perform tasks with the affected hand.29 This therapeutic approach emphasizes intensive task-specific practice with the affected hand, for three to six hours a day over a period of from two to six weeks. As in other task-oriented interventions, the therapy progresses by gradual approximations from minimal movements to fuller actions of reaching for and grasping and pinching items that a patient would ordinarily use (Table 1). Some protocols restrain the unaffected hand to force greater use of the affected hand. The key requirement, and the primary limitation, of this approach is that patients must have at least 10 degrees of finger and wrist extension, which equates to rather good motor control, in order to benefit from the therapy. As a result, perhaps only 10 percent of patients may benefit from this strategy.30 Clinical trials indicate that patients who practice at this intensity increase the amount and efficiency of use of the affected hand by 20 to 50 percent, whether therapy is begun while they are inpatients or a year after the stroke.31,32 Many technology-assisted approaches to improve the functional use of a hand have been tried. In small trials, electromyographic biofeedback, which is used to help patients focus on increasing the force of contraction necessary to move a paretic wrist or to improve pinching and grasping, has increased movement but has less often improved the functional use of the hand.33,34 Larger randomized trials of the use of acupuncture to improve functional use of the hand have shown little or no benefit when sham puncture (i.e., insertion of the needle outside a traditional zone or without stimulation) served as a control.35 Spasticity is often blamed for poor hand function in patients with minimal wrist and finger extension but some preservation of flexion. Contracture and change in the morphologic features of muscle36 contribute to a flexed posture, but poor motor control with weakness, not hypertonia, is the primary cause of disability.37 In a randomized trial, the injection of botulinum toxin into the muscles of the arm reduced excessive flexion and the associated pain, spasms, or postures that interfered with patients' self-care,38 but the induced muscle weakness usually does not improve the functional use of the hand. The injection must be followed by stretching exercises and treatment of pain that may exacerbate the hypertonicity. Walking Independent walking is a primary goal and a reasonable expectation for most patients. Inpatients who develop at least partial movement against gravity for hip flexion and knee extension will progress from single steps taken between parallel bars to at least slow walking for short distances with the use of a walker or cane and hands-on assistance from another person for balance. A molded plastic orthosis for the ankle and foot may stabilize a weak ankle and knee to improve foot clearance and prevent the knee from buckling39 without impeding the subsequent recovery of dorsiflexion in the ankle. The recovery of the ability to walk even short distances requires considerable practice. Even in a dedicated rehabilitation unit, however, patients may spend little more than 15 minutes a day engaged in mobility tasks.40 Randomized trials show that patients who walk slowly (i.e., less than 0.4 m per second) can improve their speed and endurance significantly even when treatment begins from 3 months to more than 12 months after a stroke. Successful interventions involve one or more cycles of from 12 to 20 hours of task-oriented exercise over a period of four weeks, such as practicing walking outdoors or on a treadmill or obstacle course and exercising to improve leg strength and balance.10,25 Training on a treadmill with the use of partial body-weight support (the attachment of an overhead lift to a harness on the patient's chest) allows patients to take more steps at faster speeds than may otherwise be feasible. Randomized trials initiated during inpatient rehabilitation, however, have shown clinically insignificant increases in speed and distance of walking, as compared with conventional training. More data are needed to make it possible to assess whether this approach can improve walking among patients who persistently walk poorly at three to six months after a stroke, when gains have reached an apparent plateau after conventional therapy.41 Exercise and Strengthening In patients with hemiparesis, the rates of production of muscle force, power, speed of sequential movements, and resistance to fatigue are impaired. Although neural factors that affect motor control account for much of the impairment, changes in muscle fibers and atrophy induced by inactivity may contribute. In randomized trials, progressive resistance exercises performed three to four times weekly for a period of from 6 to 12 weeks by patients with adequate motor control improved strength and functional activities.42 Fitness often declines in disabled persons, but trials show gains with progressive aerobic exercises, such as walking on a treadmill three days a week, that are tailored to each patient's tolerance, even when the exercise is initiated years after a stroke.43 Other Factors Affecting Rehabilitation Attention to modifiable conditions that may interfere with the effectiveness of efforts toward rehabilitation is routinely warranted. For example, preexisting conditions such as painful osteoarthritis or cardiopulmonary disease may limit exercise tolerance. Other modifiable factors that limit participation in exercise include sleep disorders, pain, adverse effects of medications (such as orthostatic hypotension and impaired concentration), mood disorders, and incontinence or urinary retention. Depression is especially prevalent, affecting 25 to 40 percent of patients within the first year after a stroke.44 Randomized, placebo-controlled trials of citalopram, fluoxetine, methylphenidate, and nortriptyline suggest that mid-range doses of these medications (e.g., a dose of 50 to 100 mg when a low dose is 100 mg) increase patients' participation in rehabilitation activities45 and may lessen cognitive deficits in some depressed patients.46 Other issues that are not medical, such as the costs of a caregiver and of remodeling the home to eliminate physical barriers, also affect patients' efforts and goals for rehabilitation. Areas of Uncertainty Formal therapy is often stopped when patients show no qualitative gains after a few weeks of treatment. A plateau in recovery, however, does not necessarily imply a diminished capacity for further gains in physical speed or precision or in learning a new task. At present, the opportunity to achieve maximal improvement is probably constrained by a lack of adequate data to define the optimal intensity (performance time, pace, and duration) of training strategies for specific disabilities. Functional neuroimaging studies may, in the future, help to guide decisions about the type and duration of treatment by providing insight into the maximal cortical reorganization that can be achieved with a particular therapy over time47,48; however, this possibility requires much more research. Several potential interventions need further study. Small trials have shown modest clinical improvement in disabilities after stroke with the use of the following techniques: electrical stimulation over the surface of muscles to contract them for simple movements, such as grasping, or to assist ankle dorsiflexion while walking49; intense practice with electromechanical devices that assist in reaching or stepping50; noninvasive stimulation of the peripheral nerve of the arm51 or direct stimulation of the motor cortex over the hand representation52 to augment cortical plasticity and learning during arm therapies; pharmacotherapy with agonists of dopamine, acetylcholine, and serotonin, which may modulate neurotransmission and learning53; and the use of mental imagery of an action,54 which may enhance training because it activates many of the same cortical neurons that are involved in performing the action. Phase 1 trials are beginning in order to assess the safety of the injection of drugs into the cerebrospinal fluid or of cells into brain tissue to replace neurons and promote dendrite sprouting and axon regeneration,55 with the goal of possible neural repair. Guidelines Guidelines of the American Heart Association56 and the Royal College of Physicians57 recommend the long-term use of aerobic training; exercises to enhance flexibility, balance, and coordination; and resistance exercises within daily activities for patients after a stroke. Summary and Conclusions Patients who have substantial neurologic impairments after a stroke and are expected to be able to return home, such as the one described in the vignette, are likely to benefit from inpatient rehabilitation. By the time of discharge, the patient should be able to provide reliable yes and no responses to questions and express himself or herself in short phrases, use the unaffected hand much more effectively for self-care, and walk 50 m slowly with hands-on supervision, aided by a cane and ankle–foot orthosis; he or she would be expected to need some physical help for self-care. Physical, occupational, and speech therapy after discharge should be focused on training in tasks needed to increase independence for activities at home and in the community. Successful learning of a personal skill may require 20 or more hours of practice. Formal training of caregivers should be encouraged. Treatable conditions such as depression should be identified. Ongoing improvement in movement and language skills is possible with further practice (Table 1) at any time after stroke, consistent with the plasticity of intact neural pathways. Supported by grants (HD39629, HD046740, and HD07479) from the National Institutes of Health and by the Larry L. Hillblom Foundation. Source Information From the Department of Neurology, the Neurologic Rehabilitation and Research Program, Geffen School of Medicine, University of California at Los Angeles, Los Angeles. Address reprint requests to Dr. Dobkin at the Department of Neurology, the Neurologic Rehabilitation and Research Program, Geffen School of Medicine, University of California at Los Angeles, 710 Westwood Plaza, Los Angeles, CA 90095, or at bdobkin@mednet.ucla.edu. References Centers for Disease Control. Hospitalizations for stroke among adults aged over 65 years -- United States, 2000. JAMA 2003;290:1023-1024. Hendricks HT, van Limbeek J, Geurts AC, Zwarts MJ. Motor recovery after stroke: a systematic review. Arch Phys Med Rehabil 2002;83:1629-1637. Kwakkel G, Kollen BJ, van der Grond J, Prevo AJ. 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Stroke 2004;35:127-133. Kalra L, Evans A, Perez I, et al. Training carers of stroke patients: randomised controlled trial. BMJ 2004;328:1099-1104. Legg L, Langhorne P. Rehabilitation therapy services for stroke patients living at home: systematic review of randomised trials. Lancet 2004;363:352-356. Robey RR. A meta-analysis of clinical outcomes in the treatment of aphasia. J Speech Lang Hear Res 1998;41:172-187. Greener J, Enderby P, Whurr R. Speech and language therapy for aphasia following stroke. Cochrane Database Syst Rev 2000;2:CD000425-CD000425. Bhogal SK, Teasell R, Speechley M. Intensity of aphasia therapy, impact on recovery. Stroke 2003;34:987-993. Doesborgh SJ, van de Sandt-Koenderman MW, Dippel DW, van Harskamp F, Koudstaal PJ, Visch-Brink EG. Effects of semantic treatment on verbal communication and linguistic processing in aphasia after stroke: a randomized controlled trial. Stroke 2004;35:141-146. Pulvermuller F, Neininger B, Elbert T, et al. Constraint-induced therapy of chronic aphasia after stroke. Stroke 2001;32:1621-1626. Musso M, Weiller C, Kiebel S, Muller SP, Bulau P, Rijntjes M. Training-induced brain plasticity in aphasia. Brain 1999;122:1781-1790. Peck KK, Moore AB, Crosson BA, et al. Functional magnetic resonance imaging before and after aphasia therapy: shifts in hemodynamic time to peak during an overt language task. Stroke 2004;35:554-559. Dobkin BH. Strategies for stroke rehabilitation. Lancet Neurol 2004;3:528-536. Lannin NA, Horsley SA, Herbert R, McCluskey A, Cusick A. Splinting the hand in the functional position after brain impairment: a randomized, controlled trial. Arch Phys Med Rehabil 2003;84:297-302. Steultjens EM, Dekker J, Bouter LM, van de Nes JC, Cup EH, van den Ende CH. Occupational therapy for stroke patients: a systematic review. Stroke 2003;34:676-687. Lincoln NB, Parry RH, Vass CD. Randomized, controlled trial to evaluate increased intensity of physiotherapy treatment of arm function after stroke. Stroke 1999;30:573-579. Wolf SL, Blanton S, Baer H, Breshears J, Butler AJ. Repetitive task practice: a critical review of constraint-induced movement therapy in stroke. Neurologist 2002;8:325-38. Grotta JC, Noser EA, Ro T, et al. Constraint-induced movement therapy. Stroke 2004;35:Suppl 1:2699-2701. Dromerick AW, Edwards DF, Hahn M. Does the application of constraint-induced movement therapy during acute rehabilitation reduce arm impairment after ischemic stroke? Stroke 2000;31:2984-2988. van der Lee J. Constraint-induced therapy for stroke: more of the same or something completely different? Curr Opin Neurol 2001;14:741-744. Barreca S, Wolf SL, Fasoli S, Bohannon R. Treatment interventions for the paretic upper limb of stroke survivors: a critical review. Neurorehabil Neural Repair 2003;17:220-226. Bolton DA, Cauraugh JH, Hausenblas HA. Electromyogram-triggered neuromuscular stimulation and stroke motor recovery of arm/hand functions: a meta-analysis. J Neurol Sci 2004;223:121-127. Johansson BB, Haker E, von Arbin M, et al. Acupuncture and transcutaneous nerve stimulation in stroke rehabilitation: a randomized, controlled trial. Stroke 2001;32:707-713. Lieber RL, Runesson E, Einarsson F, Friden J. Inferior mechanical properties of spastic muscle bundles due to hypertrophic but compromised extracellular matrix material. Muscle Nerve 2003;28:464-471. Sommerfeld DK, Eek EU, Svensson A-K, Holmqvist LW, von Arbin MH. Spasticity after stroke: its occurrence and association with motor impairments and activity limitations. Stroke 2004;35:134-139. Brashear A, Gordon MF, Elovic E, et al. Intramuscular injection of botulinum toxin for the treatment of wrist and finger spasticity after a stroke. N Engl J Med 2002;347:395-400. de Wilt DC, Buurke JH, Nijlant JM, Ijzerman MJ, Hermens HJ. The effect of an ankle-foot orthosis on walking ability in chronic stroke patients: a randomized controlled trial. Clin Rehabil 2004;18:550-557. Glasgow Augmented Physiotherapy Study Group. Can augmented physiotherrapy input enhance recovery of mobility after stroke? A randomized controlled trial. Clin Rehabil 2004;18:529-537. Moseley AM, Stark A, Cameron ID, Pollock A. Treadmill training and body weight support for walking after stroke. Stroke 2003;34:3006-3006. Patten C, Lexell J, Brown HE. Weakness and strength training in persons with poststroke hemiplegia: rationale, method, and efficacy. J Rehabil Res Dev 2004;41:293-312. Saunders DH, Greig CA, Young A, Mead GE. Physical fitness training for stroke patients. Cochrane Database Syst Rev 2004;1:CD003316-CD003316. Eriksson M, Asplund K, Glader EL, et al. Self-reported depression and use of antidepressants after stroke: a national survey. Stroke 2004;35:936-941. Van de Meent H, Geurts AC, Van Limbeek J. Pharmacologic treatment of poststroke depression: a systematic review of the literature. Top Stroke Rehabil 2003;10:79-92. Narushima K, Chan KL, Kosier JT, Robinson RG. Does cognitive recovery after treatment of poststroke depression last? A 2-year follow-up of cognitive function associated with poststroke depression. Am J Psychiatry 2003;160:1157-1162. Dobkin BH, Firestine A, West M, Saremi K, Woods R. Ankle dorsiflexion as an fMRI paradigm to assay motor control for walking during rehabilitation. Neuroimage 2004;23:370-381. Koski L, Mernar TJ, Dobkin BH. Immediate and long-term changes in corticomotor output response to rehabilitation: correlation with functional improvements in chronic stroke. Neurorehabil Neural Repair 2004;18:230-249. Yan T, Hui-Chan CW, Li LS. Functional electrical stimulation improves motor recovery of the lower extremity and walking ability of subjects with first acute stroke: a randomized placebo-controlled trial. Stroke 2005;36:80-85. Hesse S, Schmidt H, Werner C, Bardeleben A. Upper and lower extremity robotic devices for rehabilitation and for studying motor control. Curr Opin Neurol 2003;16:705-710. Dobkin BH. Do electrically stimulated sensory inputs and movements lead to long-term plasticity and rehabilitation gains? Curr Opin Neurol 2003;16:685-692. Hummel F, Celnik P, Giraux P, et al. Effects of non-invasive cortical stimulation on skilled motor function in chronic stroke. Brain 2005;128:490-499. Plewnia C, Hoppe J, Cohen LG, Gerloff C. Improved motor skill acquisition after selective stimulation of central norepinephrine. Neurology 2004;62:2124-2126. Liu KP, Chan CC, Lee TM, Hui-Chan CW. Mental imagery for promoting relearning for people after stroke: a randomized controlled trial. Arch Phys Med Rehabil 2004;85:1403-1408. Kondziolka D, Wechsler L, Achim C. Neural transplantation for stroke. J Clin Neurosci 2002;9:225-230. Gordon NF, Gulanick M, Costa F, et al. Physical activity and exercise recommendations for stroke survivors. Circulation 2004;109:2031-2041. Wade DT, Intercollegiate Working Party for Stroke. National clinical guidelines for stroke. London: Royal College of Physicians, 2002....查看详细 (30667字节)
☉ 11325845:Familial Cancer Associated with a Polymorphism in ARLTS1
ABSTRACT Background The finding of hemizygous or homozygous deletions at band 14 on chromosome 13 in a variety of neoplasms suggests the presence of a tumor-suppressor locus telomeric to the RB1 gene. Methods We studied samples from 216 patients with various types of sporadic tumors or idiopathic pancytopenia, peripheral-blood samples from 109 patients with familial cancer or multiple cancers, and control blood samples from 475 healthy people or patients with diseases other than cancer. We performed functional studies of cell lines lacking ARLTS1 expression with the use of both the full-length ARLTS1 gene and a truncated variant. Results We found a gene at 13q14, ARLTS1, a member of the ADP-ribosylation factor family, with properties of a tumor-suppressor gene. We analyzed 800 DNA samples from tumors and blood cells from patients with sporadic or familial cancer and controls and found that the frequency of a nonsense polymorphism, G446A (Trp149Stop), was similar in controls and patients with sporadic tumors but was significantly more common among patients with familial cancer than among those in the other two groups (P=0.02; odds ratio, 5.7; 95 percent confidence interval, 1.3 to 24.8). ARLTS1 was down-regulated by promoter methylation in 25 percent of the primary tumors we analyzed. Transfection of wild-type ARLTS1 into A549 lung-cancer cells suppressed tumor formation in immunodeficient mice and induced apoptosis, whereas transfection of truncated ARLTS1 had a limited effect on apoptosis and tumor suppression. Microarray analysis revealed that the wild-type and Trp149Stop-transfected clones had different expression profiles. Conclusions A genetic variant of ARLTS1 predisposes patients to familial cancer. Homozygous or heterozygous deletions at chromosome 13q14.3 occur in a variety of hematopoietic and solid tumors.1,2,3,4,5 In some cases of chronic lymphocytic leukemia (CLL), these deletions are the only detectable cytogenetic abnormality.6,7 The 13 known genes in this region are expressed in hematopoietic cells and solid tissues, but none have been found to be inactivated in tumors.2,8,9,10 Because of the absence of any detectable pathogenic mutation and the active transcription of all retained genes at 13q14.3 (except the microRNA genes miR-15a and miR-16-1), it is possible that haploinsufficiency, in which one allele is deleted and the remaining normal allele is insufficient to support normal function, contributes to CLL.1,8,10 To identify putative tumor-suppressor genes at 13q14.3, we sequenced and characterized a 790-kb segment spanning the minimal region of loss1 and performed a detailed mutational study of most of the known genes in this region (DLEU1, DLEU2, miR-15a, miR-16-1, RFP2, KCNRG, DLEU6, DLEU7, and DLEU8).1,11,12 Using computational and experimental approaches, we identified a gene encoding a member of the Ras superfamily, ARLTS1 (also referred to as ARL11 by the Human Genome Organisation Gene Nomenclature Committee). Here, we describe the results of studies to determine whether ARLTS1 is a tumor-suppressor gene. Methods Study Samples We studied 215 samples of sporadic tumors or blood (from 65 patients with a thyroid tumor, 58 with colorectal adenocarcinoma, 48 with breast carcinoma, 39 with CLL, and 5 with lung carcinoma) and 1 sample from a patient with idiopathic pancytopenia. The specimens of colorectal cancer and idiopathic pancytopenia were from patients in Bucharest, Romania; the breast-cancer specimens were from patients in Ferrara, Italy (38 specimens), and Aarhus, Denmark (10 specimens); the CLL samples were from patients overseen at the CLL Consortium in the United States; the lung-cancer specimens were also from patients in Ferrara; and the thyroid-tumor specimens were from patients in Naples, Italy. We obtained 109 peripheral-blood samples from patients with familial or multiple cancers: they included 69 women with BRCA1- and BRCA2-negative familial breast cancer, 17 men with both prostate cancer and malignant melanoma (negative for mutations in the p16 gene), 17 patients with familial CLL (at least two first-degree relatives affected), and 6 patients with pancreatic cancer or melanoma (with no mutations in the p16 or p14 gene and a family history of at least one case of pancreatic cancer or melanoma). A sample from only one affected member per family was analyzed. The familial CLL specimens were from patients in Paris (11 specimens) and the CLL consortium in the United States (6 specimens). All other specimens from patients with familial or multiple cancer were from Philadelphia. We also obtained 475 control blood samples from healthy people or patients with diseases other than cancer. The control samples were from 156 renal-transplantation donors in Bucharest, 203 blood donors in Ferrara, and 116 blood donors in Philadelphia. Written informed consent was obtained for the use of all specimens in accordance with the guidelines for the protection of human subjects at each participating institution. All subjects were white, as indicated by medical records in the case of the patients and information obtained during interviews with the controls. Of the patients with cancer, 58 percent were European and 42 percent were American. Of the controls, 76 percent were European and 24 percent were American. Molecular Studies Molecular studies, examination for the loss of heterozygosity, cloning of ARLTS1, and methylation studies were performed as described previously.13,14,15,16 We searched a computer database using Exofish (www.genoscope.cns.fr) and found a 182-bp, evolutionarily conserved region and obtained the full-length complementary DNA (cDNA) with the use of expressed sequence tags and rapid amplification of cDNA ends. Detection of ARLTS1 Mutations We directly sequenced DNA on both strands from 597 samples using a DNA-sequencing system (model 377, Applied Biosystems). DNA from the 203 Italian control subjects was analyzed by denaturing high-performance liquid chromatography (Transgenomics), and all the samples with abnormal patterns were directly sequenced. Stable Transfection of A549 Cells A549 is a highly tumorigenic, non–small-cell lung-carcinoma cell line that has wild-type TP53 and RB1 genes but does not express the p16INK4a gene. We constructed ARLTS1 expression vectors, one containing the full-length gene (pMV7–ARLTS1-sense) and the other containing a truncated gene encoding a protein product lacking a C-terminal and identical to the polymorphic variant implicated by the genetic data (pMV7–ARLTS1-C-terminal) by ligating the relevant open reading frame in a sense orientation into a mammalian expression vector (pMV7). All sequenced constructs were transfected with the use of FuGENE6, according to the manufacturer's instructions (Boehringer Mannheim). Stably transfected cells were selected with the use of G418 and examined for the transformed phenotype by establishing in vivo tumorigenicity in Nu/Nu nude mice and selected for apoptosis with the use of the Active Caspase-3 phycoerythrin monoclonal antibody apoptosis kit (Pharmingen, BD Biosciences). Cell-cycle profiles were identified with the use of flow cytometry of cells stained with propidium iodide, and gene-expression profiles were determined with the use of a Kimmel Cancer Center/Thomas Jefferson University human 18.5K expression bioarray (Compugen Human Oligo Set 1.0), as described previously.17 Statistical Analysis Statistical analysis of categorical results was performed with the use of Fisher's exact test. A logistic-regression model was used to determine the odds ratio for cancer in association with specific mutations. Tumor weights in immunodeficient mice were examined in an analysis-of-variance model, which included the treatment group and the time at which the animal was killed; two-sided P values for specific comparisons between groups were calculated. P values of less than 0.05 were considered to indicate statistical significance. Results Deletion of ARLTS1 in Various Types of Cancer Using Exofish18 on 1.4 Mb of the assembled genomic sequence at chromosome 13q141,11,19,20 and rapid amplification of cDNA ends, we cloned cDNA from bone marrow and spleen that encodes a conceptual protein of 196 amino acids with a predicted molecular mass of 21 kD. Analysis of protein databases with the basic local alignment search tool (BLAST) revealed significant homology with the ADP-ribosylation factor (ARF) and ARF-like (ARL) protein family of the Ras superfamily21,22; we therefore named the gene ARLTS1 (for ADP-ribosylation factor–like tumor-suppressor gene 1; GenBank accession number, AF441378 ; European Molecular Biology Laboratory–European Bioinformatics Institute Minimum Information about a Microarray Experiment accession number, E-MEXP-274). The genomic structure of ARLTS1 is very similar to that of class III ARF (ARF6): it has two exons, and the second contains the entire open reading frame. We found highly conserved protein homologues in mouse and rat and similar proteins in zebrafish, Drosophila melanogaster, and Arabidopsis thaliana (data not shown), indicating that ARLTS1 has been evolutionarily conserved over time. Previously, we reported that the genomic region at 13q14.3 is hemizygously deleted in approximately 20 percent of the CLL samples we analyzed.14 We confirmed that ARLTS1 is within the region targeted by deletions by using loss-of-heterozygosity analysis on DNA samples from 20 colorectal carcinomas; 10 percent of the specimens (2 of 20) had the hemizygous deletion (data not shown). We therefore hypothesized that monoallelic loss of ARLTS1 occurs in a fraction of both hematopoietic and solid tumors. To test this idea, we sought to identify secondary events, such as a mutation or an epigenetic alteration, that could inactivate the remaining allele. Association of a Germ-Line Truncating Polymorphism in ARLTS1 With Familial Cancer We identified a germ-line polymorphism — the substitution of adenine for guanine at position 446 (G446A), resulting in a stop codon at position 149 (Trp149Stop) (Figure 1A) — in samples from both patients with cancer and controls. The position of the stop codon predicts premature termination of translation, leading to the synthesis of a 148-amino-acid protein. Trp149 is a conserved amino acid in 12 other ARF or ARF-related proteins, including all six ARF members, whereas the stretch of 25 amino acids in the C-terminal (which is lost in the truncated form) is conserved in both mouse- and rat-homologue genes. Figure 1. The G446A (Trp149Stop) Mutation. Panel A shows the germ-line mutation G446A (Trp149Stop) (sequences are in reverse orientation). A rapid assay was developed with the use of the MaeI site introduced by the mutation. DNA was amplified with the use of a forward primer containing a base change to destroy a constitutive MaeI site and digested with 2 U of MaeI (Boehringer). Amplification of the normal allele gives rise to a single 138-bp product, whereas the mutant allele produces two bands (one 106 bp and one 32 bp). The efficiency of the digestion was low, and partial digestion products were obtained. Digested polymerase-chain-reaction products were loaded on a 3 percent agarose gel and visualized with the use of an ultraviolet imager. N denotes normal, 38T colorectal adenocarcinoma, 38N normal colon, and MCF7 a breast-carcinoma cell line. Panel B presents the pedigree of an Italian family with chronic lymphocytic leukemia (CLL) characterized by three cases of CLL in two successive generations, the phenomenon of anticipation (earlier onset and more severe phenotype in the next generation), and an increased frequency of secondary tumors (lung carcinoma, kidney carcinoma, thyroid adenoma, and essential thrombocythemia ).23 Squares indicate male family members, circles female family members, solid symbols affected family members, circle with black center an obligate carrier, and slash deceased. The family members with the G446A (Trp149Stop) mutation are indicated, as are those who are heterozygous for G/A, homozygous for A/A, and homozygous for wild-type G/G. The age at diagnosis is also shown. Because of the absence of members without the mutation, this family is not suitable for a lod analysis. The polymorphism was detected in 2.1 percent of the control subjects (Table 1), with the prevalence ranging from 0.9 percent in the U.S. population (1 in 116) to 3.4 percent in the Italian population (7 in 203). Overall, DNA from the blood of 10 of the 475 control subjects and from 8 of the 216 patients with sporadic cancer (3 of 48 with breast cancer, 2 of 58 with colorectal carcinoma, 1 of 5 with lung carcinoma, and 1 of 65 with a thyroid tumor) or idiopathic pancytopenia (1) carried the stop mutation. This difference was not significant (P=0.09). The Trp149Stop mutation was, however, significantly more frequent among patients with a family history of cancer or with multiple cancers than among patients with sporadic cancer (P=0.02; odds ratio, 5.7; 95 percent confidence interval, 1.3 to 24.8). It was found in 2 of 17 blood samples from patients with familial CLL, in 1 of 69 with familial breast cancer, in 2 of 17 patients with both malignant melanoma and prostate carcinoma, and in 1 of 6 patients with both pancreatic cancer and melanoma (Table 2). All tumor samples had both the wild-type and polymorphic alleles except one breast cancer, which lacked the wild-type ARLTS1 allele (one allele was mutated and the second was deleted). Sequence analysis of ARLTS1 in paired samples of normal tissue, which were available from two patients with a colorectal tumor and one patient with breast carcinoma, suggested that the status of the gene was the same in the normal cells and the tumor cells. Table 1. Results of ARLTS1 Sequence Analysis in Specimens of Sporadic Tumors, Blood Samples from Patients with Familial Cancer, and Blood Specimens from Control Subjects. Table 2. Clinical Characteristics of Persons with the G446A (Trp149Stop) Mutation. In one kindred with familial CLL, all five members with cancer harbored the truncating polymorphism, whereas two unaffected members who were analyzed did not (Figure 1B). The only member of this kindred with a homozygous mutation was found to have kidney carcinoma and thyroid adenoma when she was less than 50 years old. In the third generation, six members, one of whom had received a diagnosis of essential thrombocythemia (a premalignant state), had the polymorphism; the other five members were less than 40 years old. In addition to the G446A (Trp149Stop) variant, we identified four other variations in ARLTS1: C65T (Ser22Leu) and G490A (Glu164Lys), both of which were found in thyroid adenomas, and C392T (Pro131Leu) and T442C (Cys148Arg), which were present in heterozygous form in 6.2 percent and 66.9 percent, respectively, of the controls (Table 1). Glu164 is well conserved in homologues of ARLTS1 protein, suggesting that it is critical to protein function. Interestingly, we found two C65T missense mutations, one G446A nonsense mutation, and one G490A missense mutation among 23 thyroid adenomas of follicular origin, whereas wild-type ARLTS1 was present in all 42 samples of the nonfollicular type. It is unlikely that this allelic distribution is random (P=0.005 by Fisher's exact test). A member of a family with CLL who was homozygous for the G446A polymorphism also had thyroid adenoma (Table 2). Down-Regulation of ARLTS1 by Promoter Hypermethylation Analysis of RNA from normal hematopoietic and solid tissues with the use of an ARLTS1 probe revealed ubiquitous expression of a 2.2-kb transcript and additional 1.3- and 5.5-kb transcripts resulting from the use of different polyadenylation sites. Northern blotting, a semiquantitative reverse-transcriptase–polymerase-chain-reaction assay, or both showed a reduction or absence of ARLTS1 expression in 4 of 16 fresh tumor samples (2 of 7 lung carcinomas and 2 of 9 samples of CLL cells) for which cDNA, RNA, or both were available, as compared with the levels of expression in their normal counterparts (Figure 2). Figure 2. Expression of ARLTS1 Messenger RNA and Correlation of the Levels of Expression with the Level of Methylation. Panel A depicts the expression of ARLTS1 (bands at 1.3, 2.2, and 5.5 kb) by Northern blotting in eight cancer-cell lines (lanes 1 through 8). The level of expression is reduced or undetectable in several cell lines. Treatment with decitabine increases the expression in A549 cancer cells, as compared with treatment with -actin (lanes 9, 10, and 11). Panel B shows that the level of ARLTS1 expression correlates with the level of methylation of this locus analyzed by Southern blotting of digested genomic DNA with BglII alone (B) or in combination with HpaII (BH). The combination of BglII and MspI (BM) was used to determine the fragment length without respect to the degree of methylation. The presence or absence of ARLTS1 expression is shown by the plus and minus signs, respectively; in the restriction-enzyme map, BglII (B) is denoted by thick vertical lines and HpaII (H) by thin vertical lines. The position of the open-reading-frame probe used is indicated by the asterisk. Burkitt's lymphoma (AS283), T-cell acute lymphocytic leukemia (HSB2), and hairy-cell leukemia (MOT) were used for the experiments. Panel C presents the correlation between the level of ARLTS1 expression, analyzed by reverse-trancriptase–polymerase-chain-reaction assays, and the extent of methylation of the cytidine–phosphate–guanosine (CpG) site, analyzed by bisulfite sequencing in paired samples of lung-tumor tissue and normal tissue from fresh tumor, blood samples from patients with CLL (CLL 120, CLL 188, and CLL 222), and other tumor cell lines. White and black squares represent unmethylated and methylated CpG dinucleotides, respectively, and gray squares partially methylated CpG sites. As a control we used Epstein–Barr virus–transformed lymphoblastoid cell lines. N denotes normal, and T tumor. We examined tumors to determine whether ARLTS1 is down-regulated through hypermethylation of the putative promoter, which was located by a computer search of the first exon (bases 10 to 59 of the cDNA). On Southern blotting, fresh tumor samples with low levels or no expression of ARLTS1 showed higher methylation levels than normal tissues or tumors with normal levels of expression. The most 3' cytidine–phosphate–guanosine repeats (CpGs) were methylated in both normal and tumor tissues, with no correlation between the degree of methylation and the level of expression of ARLTS1, whereas the 5' CpGs located near the promoter were differentially methylated (Figure 2C). One thyroid adenoma with a heterozygous C65T (Ser22Leu) mutation also exhibited hypermethylation. Treatment of A549 cells (Figure 2A) and H1299 (data not shown) lung cancer cells with decitabine increased the levels of expression of ARLTS1 to levels similar to those in normal lung (Figure 2A). Induction of Apoptosis in Vivo by Full-Length ARLTS1 ARLTS1 expression was dramatically decreased in the A549 cell line. This line was transfected with the use of the pMV7 vector containing the full-length ARLTS1 coding sequence (ARLTS1-FL), the C-terminal–deleted cDNA (ARLTS1-Stop), or the control (empty) vector. The transfectants were selected according to the level of expression of the transfected ARLTS1 minigene (Figure 3A). We evaluated the ability of these transfected cells to form tumors in Nu/Nu mice, which lack an immune system. During eight weeks of observation, all ARLTS1-FL–transfected cells consistently formed smaller tumors (i.e., tumors that weighed 80 percent less) than did cells transfected with empty vector or wild-type A549 cells (P<0.001). Furthermore, tumor size was intermediate in the group of mice injected with A549 clones expressing the C-terminal protein (i.e., tumors weighed 50 percent less than those of wild-type A549 clones), and we found a significant difference between the size of ARLTS1-FL–induced tumors and ARLTS1-Stop–induced tumors (P=0.04) (Figure 3C and Figure 3D). Thus, ARLTS1 by itself has tumor-suppressor activity in A549 cells, and this activity is partially lost in the presence of the truncated protein. Figure 3. Effect of ARLTS1 on the Tumorigenicity of A549 Cells. Panels A and B show the restoration of expression of ARLTS1, identified by Northern blotting and Western blotting, respectively, by transfection of the minigene into A549. Panel C presents an example of tumorigenesis in nude mice. A total of 106 cells from A549 wild-type cells, A549 cells transfected with pMV7 empty vector, and several transfectant clones expressing full-length (FL) and stop (Stop) cDNA were injected subcutaneously in triplicate experiments. Panel D shows tumors from nude mice. The weight of tumors for the nine analyzed clones at the indicated times are shown. Similar results were obtained by measurement of tumor volumes. ARLTS1-AS denotes the antisense controls. A higher percentage of transfected ARLTS1-FL cells than of parental cells underwent apoptosis, whereas the populations in the G0 or G1 phase or S phase did not differ significantly between the two types of cells. By contrast, cells expressing the truncated protein were less susceptible to the induction of apoptosis than cells expressing the full-length protein (P=0.007) (Figure 4A). Western blotting showed different levels of the apoptosome complex molecules apoptotic protease-activating factor 1 and pro–caspase 9 and of the effector protein poly–ADP–ribose polymerase 1 in full-length and truncated clones (Figure 4B), with higher levels of activation in the former, in concordance with the findings in the caspase 3 assay. Figure 4. Effects of Full-Length and Truncated ARLST1 Transfectants on Apoptosis (Panels A and B) and Gene-Expression Signatures (Panel C) in A549 Cells. Panel A shows mean (±SE) flow-cytometric data on apoptotic populations from caspase 3 apoptosis experiments of transfected A549 cells. The difference in the percentage of apoptotic cells among cells transfected with ARLTS1-FL, cells transfected with ARLTS1-Stop, and wild-type A549 cells was significant on day 6 (P=0.007 by the chi-square test). Similar results were obtained by cell-cycle analysis with propidium iodide (data not shown). Panel B depicts the results of Western blotting for apoptosis proteins in ARLTS1-FL– and ARTSL1-Stop–transfected clones. Activation of the intrinsic apoptotic pathway, including the apoptosome complex molecules apoptotic protease-activating factor 1 (APAF-1) and pro–caspase 9 and the effector protein poly–ADP–ribose polymerase 1 (PARP), was observed. Levels of pro–caspase 8 (part of the extrinsic pathway) and pro–caspase 2 (indicative of stress-induced apoptosis) were not significantly affected by ARLTS1-FL or ARLTS1-Stop transfection in A549 cells. In Panel C, microarray data show distinct expression signatures for ARLTS1-FL–transfected and ARLTS1-Stop–transfected A549 cells. The latter cells had significantly lower levels of proapoptotic transcripts such as BCL2L13 and PDCD6IP or of other members of the RAS oncogene superfamily, such as ARF6, GRF2, RAB32, or RAP2C. Green denotes underexpression and red overexpression, as compared with levels of expression in untransfected A549 cells; gray indicates data not available. We also found that the gene-expression profiles of A549 cells transfected with full-length ARLTS1 minigenes differed from those of A549 cells transfected with truncated ARLTS1 minigenes (Figure 4C). The truncated transfectants had significantly lower levels of transcripts promoting apoptosis (such as BCL2L13) than did the full-length clones (P=0.003). These data are consistent with the comparative ease with which ARLTS1-FL–transfected A549 cells and ARLTS1-C–transfected A549 cells could be induced to undergo apoptosis. Furthermore, several members of the small GTPase family (such as ARF6) were expressed at significantly lower levels in the truncated transfectants (P=0.005). Together these data suggest that the full-length product increases the propensity of the cell to undergo apoptosis. Discussion We identified ARLTS1, a widely expressed member of the ARF–ARL family that functions as a tumor-suppressor gene in cancers in humans. ARFs are 20-kD guanine nucleotide-binding proteins, members of the Ras GTPase superfamily involved in various cellular functions, including vesicular transport and membrane transport.21 ARLs are structurally very similar to ARFs, and there is a continuum of ARF–ARL functions. Of the 18 known members of this family, only ARL5 has been found to be overexpressed in hepatocellular carcinoma,24 and levels of ARF6 protein correlate with the invasiveness of breast-cancer cells.25 The most common mechanism of ARLTS1 inactivation in cancers in humans seems to be biallelic down-regulation by hypermethylation of the promoter. In data consistent with the properties of a classic tumor-suppressor gene, ARLTS1 alterations were found to consist of combinations of a hypomorphic polymorphism plus loss of heterozygosity in a case of breast cancer and the polymorphism plus hypermethylation in a case of thyroid adenoma. Since the ARLTS1 G446A mutation was nearly three times as frequent among patients with familial cancers and nearly twice as high among patients with sporadic cancers as among persons in the general population, we propose that ARLTS1 is a low-penetrance tumor-suppressor gene that accounts for a small percentage of familial melanoma or familial CLL. Some kindreds may carry the polymorphism but not have cancer. A similar situation was described for other tumor-suppressor genes, such as the BRCA2 germ-line mutations in pancreatic cancer.26 An apparently neutral polymorphic stop codon has been identified in a BRCA2 gene,27 but wild-type and truncated ARLTS1 proteins were distinguishable because the truncated protein induced lower levels of apoptosis than the full-length protein when expressed in A549 cells. This observation suggests that ARLTS1 is a dose-sensitive gene, a hypotheses in accord with the variations in the levels of expression that we found in tumor samples and cell lines. The G446A (Trp149Stop) polymorphism is probably maintained in the general population, because the ARLTS1-C protein retains some functions of the full-length protein and is in the same intracellular location (unpublished data); it retains an antiapoptotic function but at a significantly lower level than does the normal product. We propose that ARLTS1-C predisposes patients to cancer in several ways. First, transfected cells harboring the truncated gene up-regulate fewer proapoptotic genes than cells with the normal gene. Second, because ARLTS1 transfection influences the levels of expression of several other members of the ARF–ARL family, the ARLTS1 product is probably involved in some common functions with other members of this family. The ARLTS-C protein induces these genes at significantly lower levels, suggesting a partial loss of common functions from the ARF–ARL spectrum. Supporting this hypothesis is the fact that the truncated protein lacks the C-terminal motif involved in nucleotide binding and hydrolysis, which are characteristic of Ras-related GTPases.28 The participation of ARLTS1 in an apoptosis pathway is in accord with data showing that the yeast homologue of ARL1 has a role in programmed cell death.29 Furthermore, a substitution in ARL1 near the position corresponding to the stop mutation that we have described inhibits the promotion of programmed cell death induced by Bax in yeast. Therefore, human ARLTS1 and yeast ARL1 may be involved in a conserved apoptosis pathway. Supported by Program Project grants (P01CA76259, P01CA81534, and P30CA56036) from the National Cancer Institute, a Kimmel Scholar award (to Dr. Bullrich), and grants from the Italian Ministry of Public Health, Italian Ministry of University Research, and Italian Association for Cancer Research (to Drs. Russo and Negrini). We are indebted to Nathalie Innocent for the confocal-microscopy analysis. Source Information From Thomas Jefferson University, Philadelphia (G.A.C., F.T., M.S., C.D.D., S.Y., D.C., S.R., H.A., H.M., T.S., R.B., C.-G.L., F.B., M.N., C.M.C.); Fox Chase Cancer Center, Philadelphia (A.K.G., B.M.); University of Ferrara, Ferrara, Italy (M.F., G. Bernardi, M.N.); the National Cancer Institute, Aviano, Italy (G. Baldassarre); Aarhus University, Aarhus, Denmark (L.L.H., J.O.); Fundeni Hospital, Bucharest, Romania (V.H.); University La Sapienza, Rome (F.R.M.); the Pasteur Institute, Paris (G.D.); the University of California San Diego, La Jolla (L.R., T.K.); the University of Catanzaro, Catanzaro, Italy (A.F.); Kyushu University, Beppu, Japan (M.M.); Istituto di Ricovero e Cura a Carattere Scientifico, Rome (G.R.); and the Dana–Farber Cancer Institute, Boston (D.N.). Address reprint requests to Dr. Croce at Ohio State University Comprehensive Cancer Center, 385K Wiseman Hall, 400 W. 12th Ave., Columbus, OH 43210, or at carlo.croce@osumc.edu. References Bullrich F, Fujii H, Calin G, et al. Characterization of the 13q14 tumor suppressor locus in CLL: identification of ALT1, an alternative splice variant of the LEU2 gene. Cancer Res 2001;61:6640-6648. Bullrich F, Croce CM. Molecular biology of chronic lymphocytic leukemia. In: Chenson BD, ed. Chronic lymphoid leukemias. New York: Marcel Dekker, 2001:9-32. La Starza R, Wlodarska I, Aventin A, et al. Molecular delineation of 13q deletion boundaries in 20 patients with myeloid malignancies. Blood 1998;91:231-237. Yin Z, Spitz MR, Babaian RJ, Strom SS, Troncoso P, Kagan J. Limiting the location of a putative human prostate cancer tumor suppressor gene at chromosome 13q14.3. Oncogene 1999;18:7576-7583. Dahlen A, Debiec-Rychter M, Pedeutour F, et al. 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The ras protein family: evolutionary tree and role of conserved amino acids. Biochemistry 1991;30:4637-4648. Abudugupur A, Mitsui K, Yokota S, Tsurugi K. An ARL1 mutation affected autophagic cell death in yeast, causing a defect in central vacuole formation. Cell Death Differ 2002;9:158-168....查看详细 (34438字节)
☉ 11325846:Leflunomide or Methotrexate for Juvenile Rheumatoid Arthritis
ABSTRACT Background We compared the safety and efficacy of leflunomide with that of methotrexate in the treatment of polyarticular juvenile rheumatoid arthritis in a multinational, randomized, controlled trial. Methods Patients 3 to 17 years of age received leflunomide or methotrexate for 16 weeks in a double-dummy, blinded fashion, followed by a 32-week blinded extension. The rates of American College of Rheumatology Pediatric 30 percent responses (ACR Pedi 30) and the Percent Improvement Index were assessed at baseline and every 4 weeks for 16 weeks and every 8 weeks during the 32-week extension study. Results Of 94 patients randomized, 86 completed 16 weeks of treatment, 70 of whom entered the extension study. At week 16, more patients in the methotrexate group than in the leflunomide group had an ACR Pedi 30 response (89 percent vs. 68 percent, P=0.02), whereas the values for the Percent Improvement Index did not differ significantly (–52.87 percent vs. –44.41 percent, P=0.18). In both groups, the improvements achieved at week 16 were maintained at week 48. The most common adverse events in both groups included gastrointestinal symptoms, headache, and nasopharyngeal symptoms. Aminotransferase elevations were more frequent with methotrexate than with leflunomide during the initial study and the extension study. Conclusions In patients with polyarticular juvenile rheumatoid arthritis, methotrexate and leflunomide both resulted in high rates of clinical improvement, but the rate was slightly greater for methotrexate. At the doses used in this study, methotrexate was more effective than leflunomide. Juvenile rheumatoid arthritis, with an estimated prevalence of 0.07 to 4.01 per 1000 children,1 has three major subtypes differentiated on the basis of onset: systemic, pauciarticular, and polyarticular (defined by the involvement of at least five joints). Treatments for juvenile rheumatoid arthritis include nonsteroidal antiinflammatory drugs (NSAIDs) and disease-modifying antirheumatic drugs (DMARDs).2,3,4,5,6,7 DMARDs have been shown radiographically to inhibit progression in adults with rheumatoid arthritis.8 Methotrexate is the most commonly used DMARD for juvenile rheumatoid arthritis. In six-month trials, both methotrexate and sulfasalazine were more effective than placebo in children with juvenile rheumatoid arthritis and had acceptable short-term safety profiles.2,5 In a randomized withdrawal trial, etanercept was effective in children with juvenile rheumatoid arthritis.3 However, no randomized, controlled trials have compared these agents with methotrexate. Leflunomide, an orally administered inhibitor of pyrimidine synthesis, has been shown to be a safe and effective long-term therapy for adults with rheumatoid arthritis.9,10,11,12,13,14 In a pilot open-label study of children with polyarticular-course juvenile rheumatoid arthritis, 52 percent of those receiving leflunomide had a response, even though all patients either had had no response to or were intolerant of methotrexate.7 To confirm these findings, we conducted a 16-week randomized, controlled comparison of leflunomide with methotrexate in children with active polyarticular-course juvenile rheumatoid arthritis. Those completing the initial 16-week study could enter a 32-week blinded extension study (total, 48 weeks). Methods Patients Patients 3 to 17 years of age were recruited from 32 centers in 12 countries (listed in the Appendix) from March 2002 to January 2003. Patients met the American College of Rheumatology (ACR) criteria for juvenile rheumatoid arthritis,15 had active polyarticular-course disease, and had not received methotrexate or leflunomide. Postpubertal and sexually active female patients had to have negative serum pregnancy tests throughout the study. Exclusion criteria included ACR functional class IV disease, active systemic symptoms within four weeks before entry, persistent or severe infection within three months before entry, or current inflammatory disease other than juvenile rheumatoid arthritis or a history of such a disease. Study Design This multinational, multicenter, randomized, controlled trial was approved by the ethics committee of each participating center and conducted in compliance with the Declaration of Helsinki. Concomitant treatment with NSAIDs and no more than 0.2 mg of prednisone or the equivalent per kilogram of body weight per day (maximum daily dose, 10 mg) was allowed, provided the dose remained unchanged beginning at least 2 weeks before enrollment and throughout the study; treatment with other DMARDs was to have been discontinued within 14 days before entry. After the patients or their parents or guardians provided written informed consent, patients were randomly assigned to receive oral leflunomide (Arava, Sanofi–Aventis) or oral methotrexate and oral matching placebo. Randomization was centralized and used double-dummy blinding. Patients weighing less than 20 kg received 100 mg of leflunomide for one day followed by a maintenance dose of 10 mg every other day. Those weighing 20 to 40 kg received 100 mg of leflunomide for two days followed by a maintenance dose of 10 mg per day. Those weighing more than 40 kg received 100 mg of leflunomide for three days followed by a maintenance dose of 20 mg per day. The dose of methotrexate was 0.5 mg per kilogram per week (maximum, 25 mg per week). All patients received at least 5 mg of folate, in the form of folic acid or folinic acid, per week (maximum, 5 mg per day). During the study, patients could receive up to two intraarticular injections of corticosteroid (triamcinolone hexacetonide), with the dose left to the discretion of the investigator; the treated joint was considered active if it was evaluated within 28 days after an injection. Patients who completed the initial 16-week study were offered continued blinded treatment in a 32-week extension study. Assessments Efficacy was assessed at baseline and every four weeks in the initial study; the two primary end points were assessed at week 16. In the extension study, efficacy was assessed every eight weeks. The two primary outcome measures were the mean Percent Improvement Index and the percentage of patients with a 30 percent improvement from baseline in at least three of the six response variables included in the ACR Pediatric core set of disease-activity measures (ACR Pedi 30) in children with juvenile rheumatoid arthritis.3,16 These measures consisted of a count of swollen joints (66 joints evaluated), a count of joints with active arthritis (68 joints evaluated), global assessment of disease activity by the patient or a parent or guardian on a visual-analogue scale ranging from 0 (disease inactive) to 100 (maximal disease activity), physician's global assessment of disease activity, assessment of physical function by the patient or a parent or guardian (by means of the Childhood Health Assessment Questionnaire Disability Index), and laboratory evaluation of acute-phase reactants (erythrocyte sedimentation rate). Patients with an ACR Pedi 30 response could also have worsening of 30 percent or more in no more than one of the six response variables. The Percent Improvement Index, a continuous variable, was calculated as the mean of the percent changes from baseline in each core set of disease-activity measures for juvenile rheumatoid arthritis, with negative values indicating improvement and positive values set to 0, indicating no improvement. Secondary outcomes included the rates of ACR Pedi 50 and ACR Pedi 70 responses (50 percent and 70 percent improvement, respectively, according to the ACR criteria), the time to an ACR Pedi 30 response, area-under-the-curve analyses, the mean changes in each core set of disease-activity measures for juvenile rheumatoid arthritis,3,16,17,18,19 and C-reactive protein concentrations. Safety variables included adverse events, findings on physical examination, and laboratory values. An independent data and safety monitoring board reviewed adverse events and laboratory data throughout the study. During the 16-week study, samples were collected at each visit for pharmacokinetic analysis. Plasma concentrations of M1 (A77-1726), the active metabolite of leflunomide, were quantified by means of high-performance liquid chromatography with ultraviolet detection. Methotrexate concentrations were not measured. Statistical Analysis All analyses of the initial 16-week study used the intention-to-treat population. Using a superiority design, we estimated that the enrollment of 37 patients per group would give the study a statistical power of 80 percent to detect an absolute difference between groups of 15 percent in the Percent Improvement Index at week 16, assuming a standard deviation of 23 percent and completion rates of 80 percent (alpha = 0.05). Analysis of variance was used to assess the mean Percent Improvement Index in the two groups as well as in various subgroups, with treatment and pooled site as fixed effects. The Cochran–Mantel–Haenszel procedure controlling for pooled site in the analysis of the rates of response was performed. Logistic regression was used to analyze the rates of response in various subgroups. Analysis of covariance was used to assess individual variables in the core set of disease-activity measures and C-reactive protein concentrations, with treatment and pooled site as fixed effects and the corresponding baseline value as the covariate. Differences in values between visits for individual patients were assessed by means of analysis of variance, with visit and patient as fixed effects for continuous variables, and by means of McNemar's test for the rates of response. All analyses were prespecified in the study protocol. Nonlinear mixed-effects models were used to analyze pharmacokinetic data on M1, the details of which have been published previously.20 The data were collected, held, and analyzed by Sanofi–Aventis. The principal investigator had access to the data and vouches for the accuracy of the data and data analysis. Results Of 103 patients who were screened, 94 underwent randomization and 86 completed the 16-week treatment: 42 of 47 in the leflunomide group (89 percent) and 44 of 47 in the methotrexate group (94 percent). Reasons for withdrawal in each group are shown in Figure 1. Six patients received intraarticular injections of corticosteroid during the initial 16 weeks (four in the methotrexate group and two in the leflunomide group). Figure 1. Enrollment and Outcomes. Two patients in the methotrexate group and one patient in the leflunomide group had a response without adverse events at week 16 but decided not to enter the extension phase for personal reasons. Of the 86 patients who completed the initial study, 70 entered the extension study (33 in the leflunomide group and 37 in the methotrexate group) (Figure 1), with completion rates at week 32 (week 48 of treatment) of 73 percent in the leflunomide group and 84 percent in the methotrexate group. Fifteen patients withdrew from the extension study (six in the methotrexate group and nine in the leflunomide group), five because of a lack of efficacy. Of the five patients who withdrew owing to a lack of efficacy, one had an ACR Pedi 70 response at that time, another had an ACR Pedi 30 response at that time, and a third entered a higher weight category without a dose adjustment. Eleven patients received intraarticular injections of corticosteroid during the extension phase (six in the methotrexate group and five in the leflunomide group). Baseline Characteristics There were no significant differences between the groups in demographic or disease characteristics at baseline (Table 1) or in the extension phase (data not shown). Table 1. Baseline Characteristics of the Patients. Pharmacokinetics The mean (±SD) steady-state concentration of M1 was 38.9±20.4 μg per milliliter (equivalent to the administration of a 20-mg dose in adults)21 among patients weighing more than 40 kg, 30.0±19.3 μg per milliliter among those weighing 20 to 40 kg, and 14.5±7.2 μg per milliliter among those weighing less than 20 kg. These findings indicate that body size (calculated as weight or body-surface area) had a relatively weak influence on the clearance of M1 (i.e., clearance did not decrease significantly as body size decreased), as reported previously.20 This effect resulted in lower concentrations of the active metabolite in patients weighing less than 40 kg. Efficacy Initial Study After adjustment for an imbalance in the numbers of patients between groups and among sites, the mean (±SE) Percent Improvement Index was similar in the leflunomide group and the methotrexate group at week 16 (–44.41±4.51 percent and –52.87±4.40 percent, respectively), and the adjusted mean difference between groups was not significant (8.46 percentage points; 95 percent confidence interval, –3.86 to 20.77; P=0.18) (Figure 2A). However, the rate of ACR Pedi 30 responses was significantly higher in the methotrexate group than in the leflunomide group (89 percent vs. 68 percent; 95 percent confidence interval, –37 to –5; P=0.02) (Figure 2B). Figure 2. Mean (±SE) Changes in the Percent Improvement Index and Rates of ACR Pedi 30 Responses in the Initial 16-Week Study, According to the Intention to Treat (Panels A and B, Respectively), and in the Extension Study (Panels C and D, Respectively). Results are from analyses between groups. Two patients in the methotrexate group were not included in the extension-study population because they withdrew before efficacy data could be obtained. For each analysis, the last observation was carried forward in the case of missing data. At week 16, the rates of ACR Pedi 50 responses were 60 percent in the leflunomide group and 77 percent in the methotrexate group (P=0.10), and the rates of ACR Pedi 70 responses were 43 percent and 60 percent, respectively (P=0.14). The median time to an ACR Pedi 30 response was 52 days in the leflunomide group and 56 days in the methotrexate group. The mean (±SE) area under the curve for the ACR Pedi 30 response rates was 1.86±0.17 months in the leflunomide group and 2.12±0.17 months in the methotrexate group; the areas under the curve for the ACR Pedi 50 response rates were 1.51±0.19 and 1.57±0.18 months, respectively; and the areas under the curve for the ACR Pedi 70 response rates were 0.88±0.17 and 0.92±0.17 months, respectively, with no significant differences between the groups. Mean changes from baseline in the core set of disease-activity variables included in the ACR Pedi 30 response did not differ clinically or significantly between the two groups (Table 2). At week 16, clinically meaningful decreases in scores for the Childhood Health Assessment Questionnaire Disability Index were reported: –0.44 in the leflunomide group and –0.39 in the methotrexate group (P=0.61). Mean changes in the erythrocyte sedimentation rate at week 16 did not differ significantly between the leflunomide and methotrexate groups (–6.5 and –7.2 mm per hour, respectively), but the methotrexate group had a significantly larger decrease in C-reactive protein concentrations (–11.4 mg per deciliter , as compared with –3.9 mg per deciliter; P=0.04). Table 2. Change from Baseline in the Core Set of Disease-Activity Variables Included in the ACR Pedi 30 Response during the Initial 16-Week Study. Logistic-regression analyses of Percent Improvement Index values and the rates of ACR Pedi 30 responses according to predefined weight subgroups revealed that weight was significantly associated with a response (Table 3). Patients weighing less than 20 kg had the greatest improvement in the Percent Improvement Index with methotrexate treatment and showed the greatest differences in the rates of response between treatment groups. These differences were even more apparent in the analysis of the rates of ACR Pedi 30 responses: logistic regression demonstrated that body weight (40 kg vs. >40 kg, P for interaction = 0.24) influenced the treatment effect. Table 3. Effects of Treatment at Week 16 in the Various Weight Subgroups. 32-Week Extension Study At week 48, there were no significant differences between the groups in the Percent Improvement Index and the rates of ACR Pedi 30 responses — the two primary outcome measures (Figure 2C and Figure 2D, respectively) — or in the rates of ACR Pedi 50 and ACR Pedi 70 responses and the mean changes from baseline in the core set of disease-activity variables or C-reactive protein concentrations. Although there was a trend toward a larger improvement between week 16 and 48 in the methotrexate group, there was no significant difference in Percent Improvement Index values at week 16 and week 48 in either the leflunomide group (–54.7 percent vs. –55.4 percent, P=0.88) or the methotrexate group (–58.0 percent vs. –65.5 percent, P=0.06). A similar analysis of the rates of ACR Pedi 30 responses did not show significant differences for either treatment (leflunomide group, 79 percent at both 16 and 48 weeks; P=1.00; methotrexate group, 91 percent at both 16 and 48 weeks; P=1.00). These results demonstrate the durability of the treatment benefit. The rates of ACR Pedi 50 responses were also maintained (leflunomide group, 73 percent at 16 weeks and 76 percent at 48 weeks; P=0.74; methotrexate group, 86 percent at both 16 and 48 weeks; P=1.00), and a trend toward a higher rate of ACR Pedi 70 responses at week 48 than at week 16 was apparent in both groups (leflunomide group, 55 percent vs. 70 percent; P=0.10; methotrexate group, 66 percent vs. 83 percent; P=0.06). There were no significant differences between groups in the mean changes from baseline in the core set of disease-activity variables and C-reactive protein concentrations. Safety Initial Study Four patients withdrew because of adverse events during the initial 16 weeks of the study: one patient in each group had liver-function abnormalities, one patient in the leflunomide group had parapsoriasis (lichenoid pityriasis), and one patient in the leflunomide group had Crohn's disease, which was judged to be unrelated to the study treatment. Serious treatment-related adverse events were reported in three patients taking leflunomide (6 percent) — suspected salmonellosis, an abnormal liver-function test, and parapsoriasis — two of which, described above, resulted in the discontinuation of treatment. No serious adverse events were reported in the methotrexate group. Data on adverse events reported in at least three patients, regardless of the treatment assignment, are provided in Table 4. Treatment-related adverse events were less frequent among patients weighing 40 kg or less. In the leflunomide group, treatment-related adverse events occurred in 4 of 8 patients weighing less than 20 kg (50 percent), 11 of 19 weighing 20 to 40 kg (58 percent), and 15 of 20 weighing more than 40 kg (75 percent); the respective values in the methotrexate group were 2 of 8 (25 percent), 6 of 13 (46 percent), and 13 of 26 (50 percent). Table 4. Adverse Events during the Initial Study and the Extension Study. Elevations in alanine aminotransferase concentrations were more than 1.2 times the upper limit of the normal range in 7 patients in the leflunomide group (15 percent) and 15 patients in the methotrexate group (32 percent) (Table 4). Elevations in alanine aminotransferase concentrations were more than 3.0 times the upper limit of the normal range in three patients in the methotrexate group, all of whom weighed 40 kg or less (one weighing less than 20 kg and two weighing 20 to 40 kg), and one patient who was in the highest weight subgroup in the leflunomide group. Neither treatment was associated with a clinically significant change in renal function, neutropenia (fewer than 500 neutrophils per cubic millimeter), or thrombocytopenia (fewer than 100,000 platelets per cubic millimeter). One patient in each group had leukopenia (fewer than 3000 leukocytes per cubic millimeter), which resolved during continued treatment. Extension Study During the extension study, five patients in the methotrexate group withdrew because of adverse events (a gastrointestinal disorder in one, a viral infection in one, and liver-function abnormalities in three), as did one patient with colitis in the leflunomide group (histologic findings were consistent with the presence of ulcerative colitis). Serious treatment-related adverse events were reported in one patient in the leflunomide group (the one with colitis) and four patients in the methotrexate group (iridocyclitis in one, a gastrointestinal disorder in one, liver-function abnormalities in one, and liver-function abnormalities, nausea, and vomiting in one). Data on adverse events reported in at least three patients are provided in Table 4. The incidence of treatment-related adverse events was similar in the leflunomide group (12 of 33 patients, or 36 percent) and the methotrexate group (15 of 37 patients, or 41 percent). Elevations in alanine aminotransferase concentrations were more than 1.2 times the upper limit of the normal range in 5 patients in the leflunomide group (15 percent) and 11 patients in the methotrexate group (30 percent) (Table 4). Elevations in alanine aminotransferase concentrations were more than 3.0 times the upper limit of the normal range in three patients in the methotrexate group (8 percent) (Table 4). Discussion In this randomized, controlled trial comparing methotrexate with leflunomide in patients with juvenile rheumatoid arthritis, the rates of response at 16 weeks were higher than expected in both groups. More patients in the methotrexate group than in the leflunomide group had an ACR Pedi 30 response (89 percent vs. 68 percent, P=0.02). Response rates in both groups compare favorably with previously published rates of ACR Pedi 30 responses of 48 percent with methotrexate,6 44 percent with sulfasalazine,5 and 74 percent after three months of open-label etanercept. Eighty percent of the patients in the open-label etanercept study maintained their response at seven months in the placebo-controlled withdrawal phase.3 We did not observe a significant difference between the methotrexate and leflunomide groups in the other primary outcome variable, the Percent Improvement Index, a continuous variable composed of the same core set of six measures as in the ACR Pedi response. There were no significant differences between groups in the mean changes in the components of the ACR Pedi 30, the ACR Pedi 50, or the ACR Pedi 70 responses. The two treatments resulted in similar and clinically meaningful improvements in physical function, since the mean changes from baseline for both treatments far exceeded the minimal clinically important improvement as reflected by the scores for the Childhood Health Assessment Questionnaire Disability Index.17 Data from the extension study demonstrated that the responses were durable and that after 48 weeks of treatment there were no significant differences in clinical responses between treatment groups with respect to the primary or secondary outcome measures or mean changes from baseline in the core set of disease-activity measures. The higher-than-expected rates of responses in both treatment groups may in part be attributed to the early stage of disease (median duration of four months) in this population, presumably because patients could not previously have received methotrexate or leflunomide. Specifically, an aggressive dosing regimen was chosen for methotrexate (0.5 mg per kilogram per week, similar to that used by Woo et al.6) because the 16-week end point was judged insufficient to accommodate dose titration. Although the dose of methotrexate per kilogram was the same for all patients, the dose of leflunomide was based on three weight categories. Among patients weighing 40 kg or less, as compared with those weighing more than 40 kg (57 percent of those in the leflunomide group and 45 percent of those in the methotrexate group), the rates of responses with methotrexate differed more from those with leflunomide. This difference was more striking in the subgroup weighing less than 20 kg than in the subgroup weighing 20 to 40 kg. The pharmacokinetic analysis suggested that the doses of leflunomide in the lower-weight patients may have been too conservative, since patients weighing 40 kg or less who were treated with leflunomide had mean M1 concentrations that were lower than those associated with clinical responses in adults with rheumatoid arthritis. Although each weight subgroup was small, the trends in clinical responses and M1 concentrations suggested that in patients weighing 40 kg or less, the true therapeutic benefit of leflunomide may have been underestimated. Overall, the safety profile with both DMARDs was consistent with their known profiles of adverse events and results in adults with rheumatoid arthritis and children with polyarticular-course juvenile rheumatoid arthritis. Methotrexate had a better safety profile than leflunomide during the initial 16 weeks of treatment, although not during the subsequent 32-week extension. The exception to this observation was that liver-function abnormalities in both the initial and extension studies were more frequent with methotrexate, including elevations in alanine aminotransferase that were more than 3.0 times the upper limit of the normal range; such elevations were reversible on discontinuation of study medication. Our patients with juvenile rheumatoid arthritis had high rates of responses to both methotrexate and leflunomide, but our findings suggest that methotrexate is more effective than leflunomide for polyarticular-course juvenile rheumatoid arthritis at the doses we used. Improvements were maintained in both groups over a total of 48 weeks of treatment. As has been true for other medications for juvenile rheumatoid arthritis, additional studies may be required to determine the response to leflunomide in the various subgroups of patients with polyarticular-course juvenile rheumatoid arthritis. Supported by Sanofi–Aventis. Dr. Simpson and Mr. Stewart are employees of Sanofi–Aventis. Dr. Horneff reports having served as a paid speaker for Sanofi–Aventis; Dr. Strand as a paid consultant and speaker for Sanofi–Aventis; and Dr. Silverman as a paid consultant for Sanofi–Aventis. We are indebted to Steven J. Kovacs, Pharm.D., and Jun Shi, M.D., M.Sc., at Sanofi–Aventis for analysis and interpretation of the pharmacokinetic data; to Joseph Doyle, R.Ph., M.B.A., formerly at Sanofi–Aventis, for contributions to the Childhood Health Assessment Questionnaire Disability Index analysis; and to Laurie Orloski, Pharm.D., for editorial assistance in the development of the manuscript. * Other investigators in the Leflunomide in JRA Investigator Group are listed in the Appendix. Source Information From the Departments of Pediatrics and Immunology, University of Toronto, Toronto (E.S.); the Division of Rheumatology, Hospital for Sick Children, Toronto (E.S., L.S.); H?pital des Enfants Malades, Paris (R.M.); the Department of Pediatrics, Creighton University Medical Center, Omaha, Nebr. (L.K.J.); University Children's Hospital, Zürich, Switzerland (R.K.S.); the Hospital for Children and Adolescents, University of Helsinki, Helsinki (P.L.); Martin Luther Uniklinik Halle, Halle, Germany (G.H.); Hospital Universitario Infantil, Valencia, Spain (I.C.); the Pediatric Rheumatology Division, Children's Hospital San Diego, San Diego, Calif. (I.S.S.); Sanofi–Aventis, Bridgewater, N.J. (K.S.); Sanofi–Aventis Pharma Canada, Laval, Que. (J.A.S.); and the Division of Immunology, Stanford University, Palo Alto, Calif. (V.S.). Address reprint requests to Dr. Silverman at the Hospital for Sick Children, 555 University Ave., Rm. 8248, Division of Rheumatology, Toronto, ON M5G 1X8, Canada, or at esilverman@sickkids.ca. References Manners PJ, Bower C. Worldwide prevalence of juvenile arthritis: why does it vary so much? J Rheumatol 2002;29:1520-1530. Giannini EH, Brewer EJ, Kuzmina N, et al. Methotrexate in resistant juvenile rheumatoid arthritis: results of the U.S.A.-U.S.S.R. double-blind, placebo-controlled trial. N Engl J Med 1992;326:1043-1049. Lovell DJ, Giannini EH, Reiff A, et al. Etanercept in children with polyarticular juvenile rheumatoid arthritis. N Engl J Med 2000;342:763-769. Lovell DJ, Giannini EH, Reiff A, et al. Long-term efficacy and safety of etanercept in children with polyarticular-course juvenile rheumatoid arthritis: interim results from an ongoing multicenter, open-label, extended-treatment trial. Arthritis Rheum 2003;48:218-226. van Rossum MA, Fiselier TJ, Franssen MJ, et al. Sulfasalazine in the treatment of juvenile chronic arthritis: a randomized, double-blind, placebo-controlled, multicenter study. Arthritis Rheum 1998;41:808-816. Woo P, Southwood TR, Prieur AM, et al. Randomized, placebo-controlled, crossover trial of low-dose oral methotrexate in children with extended oligoarticular or systemic arthritis. Arthritis Rheum 2000;43:1849-1857. Silverman E, Spiegel L, Hawkins D, et al. Long-term open-label preliminary study of the safety and efficacy of leflunomide in patients with polyarticular course juvenile rheumatoid arthritis (JRA). Arthritis Rheum (in press). Strand V, Sharp JT. Radiographic data from recent randomized controlled trials in rheumatoid arthritis: what have we learned? Arthritis Rheum 2003;48:21-34. Emery P. Disease modification in rheumatoid arthritis with leflunomide. Scand J Rheumatol Suppl 1999;112:9-14. Smolen JS, Emery P. Efficacy and safety of leflunomide in active rheumatoid arthritis. Rheumatology (Oxford) 2000;39:Suppl 1:48-56. Cohen S, Cannon GW, Schiff M, et al. Two-year, blinded, randomized, controlled trial of treatment of active rheumatoid arthritis with leflunomide compared with methotrexate. Arthritis Rheum 2001;44:1984-1992. Strand V, Cohen S, Schiff M, et al. Treatment of active rheumatoid arthritis with leflunomide compared with placebo and methotrexate. Arch Intern Med 1999;159:2542-2550. Sharp JT, Strand V, Leung H, Hurley F, Loew-Friedrich I. Treatment with leflunomide slows radiographic progression of rheumatoid arthritis: results from three randomized controlled trials of leflunomide in patients with active rheumatoid arthritis. Arthritis Rheum 2000;43:495-505. Smolen JS, Kalden JR, Scott DL, et al. Efficacy and safety of leflunomide compared with placebo and sulphasalazine in active rheumatoid arthritis: a double-blind, randomised, multicentre trial. Lancet 1999;353:259-266. Brewer EJ Jr, Bass J, Baum J, et al. Current proposed revision of JRA Criteria: JRA Criteria Subcommittee of the Diagnostic and Therapeutic Criteria Committee of the American Rheumatism Section of The Arthritis Foundation. Arthritis Rheum 1977;20:Suppl 2:195-199. Giannini EH, Ruperto N, Ravelli A, Lovell DJ, Felson DT, Martini A. Preliminary definition of improvement in juvenile arthritis. Arthritis Rheum 1997;40:1202-1209. Dempster H, Porepa M, Young N, Feldman BM. The clinical meaning of functional outcome scores in children with juvenile arthritis. Arthritis Rheum 2001;44:1768-1774. Ruperto N, Ravelli A, Pistorio A, et al. Cross-cultural adaptation and psychometric evaluation of the Childhood Health Assessment Questionnaire (CHAQ) and the Child Health Questionnaire (CHQ) in 32 countries: review of the general methodology. Clin Exp Rheumatol 2001;19:Suppl:S1-S9. Singh G, Athreya BH, Fries JF, Goldsmith DP. Measurement of health status in children with juvenile rheumatoid arthritis. Arthritis Rheum 1994;37:1761-1769. Shi J, Kovacs SJ, Ludden TM, Bhargava V. Population pharmacokinetics (PPK) analysis of A77 1726 (M1) after oral administration of leflunomide (LEF) in pediatric patients with polyarticular course juvenile rheumatoid arthritis (JRA). Clin Pharmacol Ther 2004;75:P5-P5. abstract. Rozman B. Clinical pharmacokinetics of leflunomide. Clin Pharmacokinet 2002;41:421-430....查看详细 (32513字节)
☉ 11325847:Antibiotic Treatment of Chlamydia pneumoniae after Acute Coronary Syndrome
ABSTRACT Background Chlamydia pneumoniae has been found within atherosclerotic plaques, and elevated titers of antibody to this organism have been linked to a higher risk of coronary events. Pilot studies have suggested that antibiotic treatment may reduce the risk of cardiovascular events. Methods We enrolled 4162 patients who had been hospitalized for an acute coronary syndrome within the preceding 10 days and evaluated the efficacy of long-term treatment with gatifloxacin, a bactericidal antibiotic known to be effective against C. pneumoniae, in a double-blind, randomized, placebo-controlled trial. Subjects received 400 mg of gatifloxacin daily during an initial 2-week course of therapy that began 2 weeks after randomization, followed by a 10-day course every month for the duration of the trial (mean duration, 2 years), or placebo. The primary end point was a composite of death from all causes, myocardial infarction, documented unstable angina requiring rehospitalization, revascularization (performed at least 30 days after randomization), and stroke. Results A Kaplan–Meier analysis revealed that the rates of primary-end-point events at two years were 23.7 percent in the gatifloxacin group and 25.1 percent in the placebo group (hazard ratio, 0.95; 95 percent confidence interval, 0.84 to 1.08; P=0.41). No benefit was seen in any of the prespecified secondary end points or in any of the prespecified subgroups, including patients with elevated titers to C. pneumoniae or C-reactive protein. Conclusions Despite long-term treatment with a bactericidal antibiotic effective against C. pneumoniae, no reduction in the rate of cardiovascular events was observed. Although epidemiologic studies have identified numerous risk factors for atherosclerosis, many patients do not exhibit such risk factors, and this has prompted a search for additional contributors to the progression of the disease.1 Infection with various pathogens has been implicated in the development of coronary artery disease. Specifically, Chlamydia pneumoniae has been associated with a doubling of the risk of atherosclerosis or myocardial infarction.2,3,4,5,6,7 The organism has been detected in human atheroma,5,6 and animal models have shown that new infection with C. pneumoniae results in more extensive atherosclerosis.7,8,9,10 Although not all studies show a significant relationship between IgG titers to C. pneumoniae and coronary events, a meta-analysis of more than 20 studies suggests that such a relationship does exist.11 Given the potential etiologic relationship between C. pneumoniae and cardiac events, there has been great interest in the treatment of patients who have coronary artery disease with antibiotics that are effective against chlamydia. The results of some initial pilot trials were promising,12,13 but more recent, larger studies have shown mixed results.14,15,16,17 In the largest study, patients were treated with azithromycin, a bacteriostatic antibiotic, for three months. Although no benefit was seen after a mean duration of 2.5 years of follow-up, a reduction in the rate of death or myocardial infarction was seen at 6 months,15 suggesting that long-term treatment with antibiotics might be effective in the prevention of cardiovascular events. In addition, because C. pneumoniae has a unique life cycle that includes a long, dormant intracellular phase, long-term treatment would allow better potential eradication of this organism from the vasculature. Accordingly, the Pravastatin or Atorvastatin Evaluation and Infection Therapy–Thrombolysis in Myocardial Infarction (PROVE IT–TIMI) 22 trial was set up as a two-by-two factorial design to compare long-term treatment with gatifloxacin with that of placebo for the prevention of death or major cardiovascular events in patients who had recently had an acute coronary syndrome. The study also compared standard and intensive statin therapy for the reduction of low-density lipoprotein cholesterol; the results of that comparison have been previously reported.18 Gatifloxacin is a quinolone antibiotic with bactericidal activity against C. pneumoniae and has been shown to prevent atherosclerosis in an animal model.19 Methods Patients As previously described, between November 15, 2000, and December 22, 2001, 4162 patients underwent randomization at 349 sites in eight countries.18 Men and women who were at least 18 years of age were eligible for inclusion if they had been hospitalized for an acute coronary syndrome — either acute myocardial infarction (with or without electrocardiographic evidence of ST-segment elevation) or high-risk unstable angina — within the preceding 10 days. Patients had to be in stable condition and were to be enrolled after a percutaneous revascularization procedure if one had been planned. Exclusion criteria were as previously reported.18 The protocol was approved by the relevant institutional review boards, and written informed consent was obtained from all patients. Study Protocol The protocol specified that patients receive standard medical and interventional treatment, including aspirin at a dose of 75 to 325 mg daily, with or without clopidogrel or warfarin, for acute coronary syndromes. Eligible patients underwent randomization in a 1:1 ratio to receive 400 mg of gatifloxacin daily or placebo, to be administered in a double-blind fashion. Subjects in the gatifloxacin group received an initial 2-week course of therapy beginning at the visit on day 15, followed by a 10-day course every month for the duration of the trial. The duration of follow-up ranged from 18 to 32 months, with a mean duration of 2 years. In addition, in a two-by-two factorial design, as previously reported,18 patients also underwent randomization to receive 40 mg of pravastatin or 80 mg of atorvastatin daily. Patients were seen for follow-up visits at 30 days, 4 months, and every 4 months thereafter until a final visit in August or September of 2003. Patients who discontinued treatment with the study drug during the trial were followed by telephone contact. Blood samples for the measurement of antibodies to C. pneumoniae were obtained at baseline, at 4 months, and at the final visit and underwent assay at a central core laboratory; samples for the assay (by Denka Seiken) for high-sensitivity C-reactive protein were obtained at these times and also at 30 days. In a substudy at selected centers, blood samples were obtained at baseline and at four months for assessment by polymerase chain reaction for the presence of DNA of C. pneumoniae. The dosage of the study drug could be reduced to a five-day course per month if patients had symptoms of drug intolerance, including diarrhea or nausea. The trial continued until reports of 925 events had been received at the coordinating center, after which all patients were asked to return for a final visit. Eight patients (0.2 percent) were lost to follow-up (Figure 1). 20 Figure 1. Numbers of Patients Who Were Randomly Assigned to a Treatment Group, Who Started the Assigned Treatment, and Who Discontinued Treatment or Were Lost to Follow-up. Treatment was discontinued in 699 patients in the gatifloxacin group and 622 in the placebo group for the following reasons: withdrawal of consent to treatment, 178 in the gatifloxacin group and 169 in the placebo group; withdrawal of consent to follow-up, 26 and 27, respectively (data on these patients were censored at the time they withdrew consent); discovery of a violation in protocol, 14 and 6; abnormality on electrocardiogram, 5 and 3; creatinine clearance of less than 40 milliliters per minute, 0 and 3; need for contraindicated medication, 17 and 20; drug-related side effects, 159 and 106; lack of compliance with protocol requirements, 56 and 58; other adverse events, 158 and 139; and other reasons, 86 and 91. End Points The measure of the primary efficacy outcome was the time from randomization until the first occurrence of a component of the primary end point — death from all causes, myocardial infarction, documented unstable angina that required rehospitalization, revascularization with either percutaneous coronary intervention or coronary-artery bypass surgery (if these procedures were performed at least 30 days after randomization), or stroke; the definitions of these events have been previously reported.18 Secondary end points were the risk of death from coronary heart disease, nonfatal myocardial infarction, or revascularization (if performed at least 30 days after randomization) and the risk of death from coronary heart disease or of nonfatal myocardial infarction, as well as the individual components of the primary end point. Prespecified subgroup analyses were performed among patients with elevated C. pneumoniae antibody titers and according to quintiles of C-reactive protein levels at baseline as well as sex, smoking status, and the presence or absence of diabetes mellitus. Statistical Analysis We compared the results of treatment with gatifloxacin with those of placebo using Kaplan–Meier analyses of event rates as well as Cox proportional-hazards ratios over the duration of follow-up. On the assumption that there would be a two-year event rate of 24 percent in the placebo group during an average of two years of follow-up, a total of 2000 patients per group was considered necessary to yield 925 primary end points and give the study 94 percent power to detect a 19 percent reduction in the primary end point. This was based on a hypothesis that treatment with antibiotics would lead to a 20 percent reduction in events; however, because we were starting treatment with the drug on day 15, and no benefit could be derived before this, a 19 percent overall reduction of risk would be expected. Allocation of treatment was based on a central randomization system in which treatment was assigned according to the method of randomized permuted blocks of patients, stratified according to center. Two interim assessments of efficacy and safety were carried out by an independent data and safety monitoring board. Rules for early cessation due to the superiority of either treatment were not prespecified. All efficacy analyses were based on the intention-to-treat principle. Estimates of hazard ratios and associated 95 percent confidence intervals for the comparison of gatifloxacin with placebo were obtained with the Cox proportional-hazards model, with randomized treatment as the covariate and stratification according to statin group. With the two-by-two factorial design, a test for interaction with statins was carried out, and no interaction was found with the groups receiving treatment with statins. The investigators designed the trial and had free and complete access to the data. The study was designed by the TIMI Study Group. Data coordination was performed by the Nottingham Clinical Research Group.18 Investigators from TIMI, the sponsor, and Nottingham performed data analysis jointly, and all groups vouch for the data. Results The two groups of enrolled patients were similar (Table 1). Their average age was 58 years, and 22 percent were women. Before their index event, 38 percent of patients had evidence of previous cardiovascular disease, and 18 percent had diabetes mellitus. As their index event, approximately one third had high-risk unstable angina, one third had myocardial infarction associated with electrocardiographic ST-segment elevation, and one third had myocardial infarction without such elevation. Sixty-nine percent of patients had undergone percutaneous coronary intervention for treatment of their index acute coronary syndrome before randomization. Concomitant medications were administered to patients during the treatment period as follows: aspirin, 93 percent; warfarin, 8 percent; clopidogrel or ticlodipine, 72 percent initially and 20 percent at one year; beta-blockers, 85 percent; angiotensin-converting–enzyme (ACE) inhibitors, 69 percent; and angiotensin-receptor blockers, 14 percent. The study drug was administered for an average of 1.6 years in the gatifloxacin group and 1.7 years in the placebo group. By one year, 74.4 percent of patients in the gatifloxacin group and 80.0 percent of those in the placebo group were taking the study drug. There were 3025 and 3272 patient-years of exposure to gatifloxacin and placebo, respectively. Table 1. Baseline Characteristics of the Patients. For all randomized patients, Kaplan–Meier estimates of the event rates for the primary end point at two years were 23.7 percent in the gatifloxacin group and 25.1 percent in the placebo group (Figure 2), representing a hazard ratio of 0.95 (95 percent confidence interval, 0.84 to 1.08; P=0.41). The risk associated with the secondary end point of death due to coronary heart disease, myocardial infarction, or revascularization also was not significantly reduced among patients receiving gatifloxacin, with a rate of 20.4 percent as compared with 21.6 percent among those receiving placebo (hazard ratio, 0.95; 95 percent confidence interval, 0.84 to 1.09; P=0.48). The risk of death due to coronary heart disease or myocardial infarction was also not significantly reduced in the gatifloxacin group, at 7.6 percent as compared with 8.0 percent in the placebo group (hazard ratio, 0.97; P=0.78). There was no reduction in the individual components of the primary end point among patients treated with gatifloxacin (Figure 3). Figure 2. Kaplan–Meier Estimates of Events over Time among Patients Treated with Gatifloxacin or Placebo. Events were defined as deaths or major cardiovascular events, and rates noted were at two years. Figure 3. Risk Reduction for Death or a Major Cardiovascular Event and Event Rates at Two Years. Squares denote hazard ratios, and horizontal lines 95 percent confidence intervals. The primary end point was defined as a composite of death from all causes, myocardial infarction, documented unstable angina requiring rehospitalization, revascularization (performed at least 30 days after randomization), and stroke. Percent change in risk was calculated from hazard ratios. No benefit from gatifloxacin was observed among prespecified clinical subgroups in terms of either the primary end point (Figure 4) or the secondary end point of death from coronary heart disease or myocardial infarction (data not shown). Testing of baseline IgG antibody titers to C. pneumoniae did not identify a subgroup of patients who benefited from antibiotic treatment (Figure 4), including the 5 percent of patients who had the highest baseline titers (greater than 1:512) (data not shown). There was no effect of gatifloxacin on antibody titers over the trial period. In the placebo group, there was a decrease in antibody titers over time, with the percentage of patients in whom titers were elevated falling from 64.6 percent at baseline to 52.4 percent at the final visit (P<0.001). An identical pattern was seen in the gatifloxacin group, with a fall from 64.0 percent at baseline to 53.5 percent at the final visit (P<0.001). The P value for interaction was not significant, and thus treatment with gatifloxacin did not influence antibody titers to C. pneumoniae. In the substudy that assessed the presence of DNA for C. pneumoniae in peripheral mononuclear blood cells, only 6 of 171 patients in the placebo group (3.5 percent) and 6 of 172 in the gatifloxacin group (3.5 percent) were positive at baseline. At four months, among 80 patients who received gatifloxacin and 89 who received placebo with follow-up blood samples, 3 (3.8 percent) and 4 (4.5 percent), respectively, were positive (P not significant). Figure 4. Hazard Ratios for Death or a Major Cardiovascular Event, with Two-Year Event Rates, According to Baseline Characteristics. Squares denote hazard ratios, and horizontal lines 95 percent confidence intervals. None of the tests for interaction were significant. The median C-reactive protein level was 12.1 mg per liter. Use of levels of C-reactive protein at baseline to define subgroups according to either the median level of 12.1 mg per liter (Figure 4) or according to quintile did not identify any subgroups that had a benefit from gatifloxacin. Over the duration of the trial, there were no differences in achieved C-reactive protein levels between patients receiving gatifloxacin and those receiving placebo; in each group, the level was 1.7 mg per liter at four months and 1.8 mg per liter at the final visit (P not significant for either time). Tolerability and Safety As expected, the side effects of diarrhea and nausea or vomiting associated with antibiotic treatment were significantly more common among patients receiving gatifloxacin (8.1 percent had diarrhea, and 7.3 percent nausea or vomiting; P=0.01) than among those receiving placebo (6.1 percent and 5.5 percent, respectively; P=0.02). Slight changes in blood glucose levels were noted in the gatifloxacin group, as previously reported with this agent.21 Among patients who did not have diabetes mellitus at baseline, new-onset diabetes (defined as the presence of one or more nonfasting serum glucose values of 200 mg per deciliter, two or more nonfasting serum glucose values of 140 mg per deciliter, or two or more fasting serum glucose values of 126 mg per deciliter) tended to develop more frequently in patients treated with gatifloxacin than in those given placebo (4.6 percent vs. 3.4 percent, P=0.08). Among patients with diabetes, there were trends toward more patients who were treated with gatifloxacin having episodes of hyperglycemia than patients who were treated with placebo (30.7 percent vs. 25.4 percent, P=0.11) and toward more patients who were treated with gatifloxacin having episodes of hypoglycemia (2.6 percent vs. 1.5 percent, P=0.32). Conversely, fewer upper respiratory tract infections developed in patients receiving the monthly courses of gatifloxacin than in patients receiving placebo (10.9 percent vs. 14.8 percent, P<0.001), and fewer sinus infections developed in patients in the gatifloxacin group than in those in the placebo group (4.6 percent vs. 6.5 percent, P=0.01). Discussion Although there is evidence to suggest that C. pneumoniae has a role in the development of atherosclerosis, we were not able to detect a benefit from long-term antibiotic therapy in patients who had recently been hospitalized for an acute coronary syndrome. These results are in agreement with those of Grayston et al., reported elsewhere in this issue of the Journal.22 There was no reduction in the primary end point, the secondary end points, or any of the individual components of the primary end point as a result of antibiotic treatment. None of the prespecified subgroups, distinguished by high-risk clinical characteristics, C-reactive protein levels, antibody titers to C. pneumoniae, or the presence of C. pneumoniae within peripheral mononuclear blood cells, showed any benefit from the antibiotic treatment. Thus, our findings suggest that for patients who have had a recent acute coronary syndrome and who have established cardiovascular disease, antibiotic therapy is not effective in reducing the risk of recurrent cardiovascular events. When these findings are juxtaposed with the significant benefit of intensive statin therapy as compared with standard statin therapy that was observed in the same trial,18 the results reinforce the importance of using proven therapies for secondary prevention in this population. Our trial differed from prior studies of antibiotics12,13,14,15,16,17 in that it involved a large number of high-risk patients with acute coronary syndromes, among whom more than 1000 primary end points were observed; the trial thus had a more than 97 percent power to detect (or rule out) a benefit from antibiotic treatment of 19 percent and an 85 percent power to detect (or rule out) a benefit of 17 percent. In addition, we continued antibiotic treatment longer than any of the prior trials, using monthly courses of therapy throughout the two-year duration of the trial. We studied patients with acute coronary disease, the severity of which, it had been thought, would allow C. pneumoniae to be potentially active within coronary lesions. Finally, full-dose gatifloxacin, a bactericidal quinolone antibiotic known to be destructive to C. pneumoniae, was used, in contrast to the bacteriostatic macrolide antibiotics that were used in prior studies. Despite the long-term, full-dose antibiotic treatment, no reduction in cardiac events was observed with antibiotic treatment in patients who had recently been hospitalized for an acute coronary syndrome. In determining the potential reasons why antibiotic treatment was not effective, we assessed disease activity in several ways. The substudies point to an absence of active infection in the middle-aged patients with established coronary disease who were enrolled. With the use of serial antibodies to C. pneumoniae, no increase in titers was observed, as would be expected if patients had active infection with the organism. These findings were supported by the substudy that found that only 4 percent of patients had evidence of C. pneumoniae in their mononuclear blood cells (a marker that has been shown in other studies to be well correlated with the presence of C. pneumoniae in arterial plaque).2,23 Finally, there was no effect of antibiotic treatment on levels of C-reactive protein, a marker of inflammation, which might have been elevated by C. pneumoniae. Thus, the overall clinical results and the results of the three substudies within the trial suggest that patients were not actively infected with C. pneumoniae and that, accordingly, antibiotic therapy had no detectable effect. Because the serologic and pathological evidence supports the likelihood of prior infection and the presence of C. pneumoniae within arterial plaque, it is possible that infection with C. pneumoniae is part of the initiation of atherosclerosis in the early decades of life but not an active part of the progression of disease later, when patients have established coronary artery disease. Indeed, the animal model that has shown a benefit of antibiotic therapy with either azithromycin or gatifloxacin is that of cholesterol-fed rabbits, in which antibiotic treatment at the time of initial infection can reduce the development of atherosclerosis.7,19 No model of established vascular disease has been used to show that the use of antibiotics reverses or slows the progression of the disease. The situation may be similar to that of other infections such as those involving the Epstein–Barr virus, which is a well-established cause of Burkitt's lymphoma. However, among patients in whom the lymphoma develops, treatment is not with antiviral agents but, rather, with chemotherapeutic agents. Thus, it is possible that C. pneumoniae is a cause of early atherosclerosis but that once the process is established, with the appearance of cholesterol-laden plaque and inflammation, therapy with antichlamydial antibiotics is not effective. Accordingly, the two components of the PROVE IT–TIMI 22 trial highlight the proven benefit of intensive statin therapy after acute coronary syndromes, as recently advocated in an update to the guidelines of the National Cholesterol Education Program.24 Efforts toward secondary prevention in patients with these syndromes should be aimed at proven therapies, including antiplatelet therapy, treatment with beta-blockers and ACE inhibitors, and intensive lowering of lipid levels with the use of statins. Supported by Bristol-Myers Squibb and Sankyo. Dr. Cannon reports having received grant support from AstraZeneca, Bristol-Myers Squibb, Merck, and Sanofi–Aventis and having served on paid advisory boards for AstraZeneca, Bristol-Myers Squibb, GlaxoSmithKline, Pfizer, Sanofi–Aventis, and the Merck–Schering-Plough partnership. Dr. Braunwald reports having received grant support from Sanofi–Aventis and Bristol-Myers Squibb. Ms. McCabe reports having received grant support from AstraZeneca, Sanofi–Aventis, and Bristol-Myers Squibb. The Azithromycin and Coronary Events Study, for which Dr. Grayston was the principal investigator, received partial grant support from Pfizer. Dr. Muhlestein reports having received grant support from and having served on paid advisory boards for Bristol-Myers Squibb. Dr. Giugliano reports having received lecture fees from Bristol-Myers Squibb. Source Information From the Thrombolysis in Myocardial Infarction Study Group, Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston (C.P.C., E.B., C.H.M., R.P.G.); the Department of Epidemiology, University of Washington, Seattle (J.T.G.); LDS Hospital, Salt Lake City (B.M.); and Nottingham Clinical Research Group, Nottingham, United Kingdom (R.C., A.M.S.). Address reprint requests to Dr. Cannon at the TIMI Study Group, Cardiovascular Division, Brigham and Women's Hospital, 75 Francis St., Boston, MA 02115, or at cpcannon@partners.org. References Libby P, Ridker PM, Maseri A. Inflammation and atherosclerosis. Circulation 2002;105:1135-1143. Danesh J, Collins R, Peto R. Chronic infection and coronary heart disease: is there a link? Lancet 1997;350:430-436. Libby P, Egan D, Skarlatos S. Roles of infectious agents in atherosclerosis and restenosis: an assessment of the evidence and need for future research. Circulation 1997;96:4095-4103. Kuo CC, Shor A, Campbell LA, Fukushi H, Patton DL, Grayston JT. Demonstration of Chlamydia pneumoniae in atherosclerotic lesions of coronary arteries. J Infect Dis 1993;167:841-849. Muhlestein JB, Hammond EH, Carlquist JF, et al. Increased incidence of Chlamydia species within the coronary arteries of patients with symptomatic atherosclerotic versus other forms of cardiovascular disease. J Am Coll Cardiol 1996;27:1555-1561. Kuo CC, Grayston JT, Campbell LA, Goo YA, Wissler RW, Benditt EP. Chlamydia pneumoniae (TWAR) in coronary arteries of young adults (15-34 years old). Proc Natl Acad Sci U S A 1995;92:6911-6914. Muhlestein JB, Anderson JL, Hammond EH, et al. Infection with Chlamydia pneumoniae accelerates the development of atherosclerosis and treatment with azithromycin prevents it in a rabbit model. Circulation 1998;97:633-636. Fong IW, Chiu B, Viira E, Fong MW, Jang D, Mahony J. Rabbit model for Chlamydia pneumoniae infection. J Clin Microbiol 1997;35:48-52. Moazed TC, Campbell LA, Rosenfeld ME, Grayston JT, Kuo CC. Chlamydia pneumoniae infection accelerates the progression of atherosclerosis in apolipoprotein E-deficient mice. J Infect Dis 1999;180:238-241. Danesh J, Whincup P, Walker M, et al. Chlamydia pneumoniae IgG titres and coronary heart disease: prospective study and meta-analysis. BMJ 2000;321:208-213. Danesh J, Whincup P, Walker M, et al. Low grade inflammation and coronary heart disease: prospective study and updated meta-analyses. BMJ 2000;321:199-204. Gupta S, Leathan EW, Carrington D, Mendall MA, Kaski JC, Camm AJ. Elevated Chlamydia pneumoniae antibodies, cardiovascular events, and azithromycin in male survivors of myocardial infarction. Circulation 1997;96:404-407. Gurfinkel E, Bozovich G, Daroca A, Beck E, Mautner B. Randomised trial of roxithromycin in non-Q-wave coronary syndromes: ROXIS Pilot Study. Lancet 1997;350:404-407. Neumann F, Kastrati A, Miethke T, et al. Treatment of Chlamydia pneumoniae infection with roxithromycin and effect on neointima proliferation after coronary stent placement (ISAR-3): a randomised, double-blind, placebo-controlled trial. Lancet 2001;357:2085-2089. O'Connor CM, Dunne MW, Pfeffer MA, et al. Azithromycin for the secondary prevention of coronary heart disease events: the WIZARD study: a randomized controlled trial. JAMA 2003;290:1459-1466. Cercek B, Shah PK, Noc M, et al. Effect of short-term treatment with azithromycin on recurrent ischaemic events in patients with acute coronary syndrome in the Azithromycin in Acute Coronary Syndrome (AZACS) trial: a randomised controlled trial. Lancet 2003;361:809-813. Zahn R, Schneider S, Frilling B, et al. Antibiotic therapy after acute myocardial infarction: a prospective randomized study. Circulation 2003;107:1253-1259. Cannon CP, Braunwald E, McCabe CH, et al. Intensive versus moderate lipid lowering with statins after acute coronary syndromes. N Engl J Med 2004;350:1495-1504. Jones HU, Muhlestein JB, Lim TH, et al. Short-term therapy with gatifloxacin or azithromycin prevents the acceleration of atherosclerosis after infection with Chlamydia pneumoniae in a rabbit model but does not eradicate the organism from plaque. J Am Coll Cardiol 2003;41:289A-289A. abstract. Wang SP, Kuo CC, Grayston JT. Formalinized Chlamydia trachomatis organisms as antigen in the micro-immunofluorescence test. J Clin Microbiol 1979;10:259-261. Gajjar DA, LaCreta FP, Kollia GD, et al. Effect of multiple-dose gatifloxacin or ciprofloxacin on glucose homeostasis and insulin production in patients with noninsulin-dependent diabetes mellitus maintained with diet and exercise. Pharmacotherapy 2000;20:76S-86S. Grayston JT, Kronmal RA, Jackson LA, et al. Azithromycin for the secondary prevention of coronary events. N Engl J Med 2005;352:1637-1645. Juvonen J, Juvonen T, Laurila A, et al. Demonstration of Chlamydia pneumoniae in the walls of abdominal aortic aneurysms. J Vasc Surg 1997;25:499-505. Grundy SM, Cleeman JI, Merz CNB, et al. Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III guidelines. Circulation 2004;110:227-239....查看详细 (29962字节)
☉ 11325848:Azithromycin for the Secondary Prevention of Coronary Events
ABSTRACT Background Epidemiologic, laboratory, animal, and clinical studies suggest that there is an association between Chlamydia pneumoniae infection and atherogenesis. We evaluated the efficacy of one year of azithromycin treatment for the secondary prevention of coronary events. Methods In this randomized, prospective trial, we assigned 4012 patients with documented stable coronary artery disease to receive either 600 mg of azithromycin or placebo weekly for one year. The participants were followed for a mean of 3.9 years at 28 clinical centers throughout the United States. Results The primary end point, a composite of death due to coronary heart disease, nonfatal myocardial infarction, coronary revascularization, or hospitalization for unstable angina, occurred in 446 of the participants who had been randomly assigned to receive azithromycin and 449 of those who had been randomly assigned to receive placebo. There was no significant risk reduction in the azithromycin group as compared with the placebo group with regard to the primary end point (risk reduction, 1 percent ). There were also no significant risk reductions with regard to any of the components of the primary end point, death from any cause, or stroke. The results did not differ when the participants were stratified according to sex, age, smoking status, presence or absence of diabetes mellitus, or C. pneumoniae serologic status at baseline. Conclusions A one-year course of weekly azithromycin did not alter the risk of cardiac events among patients with stable coronary artery disease. An association between Chlamydia pneumoniae and atherosclerosis, originally suggested by seroepidemiologic studies,1,2 was confirmed by a series of investigations demonstrating the presence of the organism in atherosclerotic lesions by four different methods.3,4,5,6 The etiologic or pathogenic significance of this association needs to be determined. Through basic-science studies of possible mechanisms and animal-model studies of atherosclerosis, data on the role of C. pneumoniae in atherosclerosis have accumulated.7,8 The presence of C. pneumoniae in atherosclerotic lesions raises the possibility that antibiotic treatment might have a favorable effect on the course of coronary heart disease. A trial of antibiotic treatment in humans would be justified because of the public health importance of coronary heart disease. Moreover, it should be safe for the participants. Prior studies of both short- and long-term administration of macrolide antibiotics, including azalides, have shown few adverse reactions.9,10 Chlamydiae have not developed resistance against macrolide antibiotics, but long-term antibiotic therapy could contribute to resistance in other organisms. However, the risk that resistant bacteria might emerge during the trial was offset by the current practice among some physicians of providing antibiotic treatment for coronary heart disease in the absence of any established benefit.11 Methods Study Population We conducted a randomized, double-blind, placebo-controlled trial at 28 centers in the United States. Men and women 18 years of age or older who had documented, stable coronary heart disease (defined as a previous myocardial infarction documented on the basis of enzyme-related criteria, angiographic evidence of at least 50 percent stenosis of a coronary artery, or previous coronary revascularization) were eligible. Patients were excluded if during the preceding three months they had had a myocardial infarction, undergone coronary revascularization, or been hospitalized for unstable angina. Additional reasons for exclusion were severe cardiac disease (New York Heart Association class III or IV congestive heart failure or stage III or IV angina), allergy to macrolide antibiotics, clinically significant renal or hepatic dysfunction, cancer, ongoing antibiotic therapy, or immunosuppression. Written informed consent was obtained from all the participants. Treatment and Follow-up Patients were enrolled in the Azithromycin and Coronary Events Study (ACES) between April 1999 and May 2000, and follow-up concluded on December 31, 2003. Participants were randomly assigned to receive either a 600-mg azithromycin tablet or a matching placebo tablet once weekly for one year. Azithromycin was chosen for treatment because of its proven efficacy against chlamydial infection and its long intracellular half-life, which allowed once-weekly dosing. Participants and all site investigators remained blinded to the treatment assignment through the end of follow-up and data collection. Participants were interviewed in person or by telephone 3 weeks, 6 weeks, and 3, 6, 9, and 12 months after enrollment to identify adverse events and study outcomes and to ascertain their compliance with the study medication. After the first year, participants were interviewed approximately every six months until the end of follow-up to identify outcomes. End Points The primary end point was a composite of the first occurrence of any of the following: death due to coronary heart disease, nonfatal myocardial infarction, a percutaneous or surgical coronary revascularization procedure, or hospitalization for unstable angina. The members of a clinical end-point committee, who were blinded to the treatment-group assignment, adjudicated the end points. Two committee members adjudicated each end point separately, and if there was disagreement, a third member resolved the difference. Myocardial infarction was defined by hospitalization with a clinical syndrome compatible with infarction and either the development of a new pathologic Q wave or diagnostic elevations in the creatine kinase MB level (or troponin level if creatine kinase MB results were not available) above the upper limit of normal for the treating institution. It was also diagnosed in patients resuscitated after cardiac collapse with creatine kinase MB or troponin levels greater than the upper limit of the normal range. Myocardial infarction was also diagnosed according to the following criteria in patients who had undergone revascularization: within the first 48 hours after coronary bypass surgery in patients with creatine kinase MB levels greater than five times the upper limit of the normal range; within the first 48 hours after percutaneous revascularization in those with creatine kinase MB levels greater than three times the upper limit of the normal range; and after 48 hours in those who had undergone either procedure and had creatine kinase MB or troponin levels above the upper limit of the normal range. Unstable angina was defined by hospitalization for new chest pain or changes in the patient's usual chest pain in combination with electrocardiographic ST-T wave changes indicative of ischemia or accompanied by elevations in enzyme markers not diagnostic of myocardial infarction. Death due to coronary heart disease was defined as death believed to be the consequence of coronary atherosclerotic disease or death not definitively known to be due to a noncoronary cause. Death from cardiac causes included death due to arrhythmias, severe congestive heart failure, cardiogenic shock, or myocardial infarction. Unwitnessed sudden death in the absence of a noncoronary cause was assumed to be death from coronary heart disease. Death within 30 days after coronary revascularization was considered to be due to coronary heart disease, unless another cause unrelated to the procedure or to coronary disease was clearly identified. Components of the primary end point were analyzed separately. Predefined secondary end points included stroke, cardiac collapse followed by resuscitation, carotid endarterectomy, peripheral revascularization, and death from any cause. Participants who had a nonfatal event were followed to the end of the trial so that the total rate of the individual events constituting the primary end point could be compared between the treatment groups. Laboratory Tests Blood specimens were obtained from all participants at enrollment. They were tested for the presence of C. pneumoniae antibody in the IgG and IgA serum fractions by the microimmunofluorescence test12 and for total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. Statistical Analysis Calculations In the calculation of the sample size, it was assumed that the rate of the primary end point would be 6.5 percent per year in the placebo group, on the basis of previous trials. With the use of this estimate, the planned sample size of 4000, with an average follow-up of 4.0 years, allowed 98 percent power to detect a 25 percent reduction and 85 percent power to detect a 20 percent reduction in the rate of the primary end point at a two-sided significance level of 0.05. Data analyses were based on an intention-to-treat approach. In the primary analysis, the time to the primary end point in the azithromycin group was compared with that in the placebo group with use of the log-rank test. Components of the primary end point and secondary end points were similarly analyzed. Participants' data were censored on the date of the last contact or the date of death. Final visits occurred within a three-month period from October 1 through December 31, 2003. The Cox proportional-hazards model was used to compute hazard ratios and the percent risk reduction . The curve representing the cumulative rate of the primary end point was estimated by the product-limit (Kaplan–Meier) method. Safety Monitoring and Stopping Guidelines The National Heart, Lung, and Blood Institute appointed an independent data and safety monitoring board. The study was conducted under an investigational-new-drug application with the Food and Drug Administration (FDA). The institutional review board at each site approved the protocol. The data and safety monitoring board monitored the study for safety and efficacy. To preserve the overall type I error, a group sequential approach was used to determine interim monitoring boundaries for stopping the trial owing to a demonstration of the superiority of azithromycin over placebo with use of the log-rank test. Planned interim analyses were performed when approximately one quarter, one half, and three quarters of the expected number of events had occurred, at significance levels of 0.0017, 0.0020, and 0.0023. At each interim analysis, the data and safety monitoring board voted unanimously to continue the study. Dr. Grayston designed the study with the assistance of Drs. Kronmal and Jackson. The data gathered at the 28 sites (listed in the Appendix) were collected and evaluated at Axio Research, under the direction of Ms. Borrowdale. Dr. Kronmal analyzed the data with assistance from Drs. Grayston and Jackson. Dr. Grayston and all the authors vouch for the data and the analysis. All the authors contributed to the writing of the manuscript, under the direction of Dr. Grayston. Results ACES enrolled 4012 patients; 2004 were randomly assigned to the azithromycin group and 2008 to the placebo group. Of those enrolled, one in the azithromycin group and two in the placebo group did not receive any study drug. Table 1 shows the characteristics of the participants at enrollment. Fifty-six percent of the participants had had a myocardial infarction, and 89 percent had undergone a coronary revascularization procedure. Twenty-nine percent reported angina at rest, 28 percent had angina only on exertion, and 12 percent had congestive heart failure. Table 1. Baseline Characteristics of Participants in ACES, According to Study Group. Only 86 of the participants (2 percent) withdrew consent or were lost to follow-up. They were divided approximately equally between the azithromycin group (44 participants) and the placebo group (42 participants). Ninety-seven percent of 45,363 scheduled follow-up visits were successfully completed. The median length of observation was 3.91 years in the azithromycin group and 3.92 years in the placebo group. Eighty-eight percent of the participants in the azithromycin group and 93 percent of those in the placebo group completed the one-year period of weekly treatment. The frequency of the primary end point was 22.3 percent in the azithromycin group and 22.4 percent in the placebo group. There was a reduction of 1 percent in the risk of the primary end point in the azithromycin group (95 percent confidence interval, –13 to 13 percent). The curve representing the cumulative rate of the primary end point in each of the two groups over time is presented in Figure 1. Figure 1. Kaplan–Meier Curves Representing the Cumulative Rate of the Primary End Point, According to Study Group. The proportion of participants with each of the individual events contributing to the primary end point is shown in Table 2. There was no significant difference between the azithromycin group and the placebo group in the frequency of any individual event. Table 3 shows the frequency of all of the primary and secondary outcome events throughout the study, regardless of whether they occurred after the participant had a prior event. Again, there was no difference between the groups with respect to the frequency of primary or secondary end-point events. Table 2. Proportion of Participants with Each Event Contributing to the Primary End Point, According to Event and Study Group. Table 3. Proportion of Participants with Primary or Secondary End-Point Events, According to Type of Event and Study Group. Subgroup analyses of the primary end point according to individual baseline characteristics considered to be coronary risk factors are shown in Figure 2. In these analyses, there were no significant differences between the azithromycin group and the placebo group in the risk of the primary end point. There was also no difference between the groups when other baseline characteristics, including angina at rest, angina on exertion, prior revascularization, and prior myocardial infarction were analyzed. Figure 2. Risk of the Primary End Point Associated with Azithromycin Treatment, Stratified According to Baseline Characteristics Considered to Be Coronary Risk Factors. The size of the rectangles is proportional to the reciprocal of the variance of the hazard ratio. C. pneumoniae antibody status was determined by testing blood specimens obtained at enrollment. Twenty percent of the participants did not have antibody in the IgG serum fraction, and two thirds did not have IgA antibody. Neither IgG antibody nor IgA antibody was significantly associated with the risk of the primary end point in either the azithromycin or placebo group. Symptoms reported by participants during interviews at intervals during the year of treatment and the number of participants who reported seeking medical care for these symptoms are shown in Table 4. Clinical or laboratory follow-up data on the reported symptoms were not obtained. Although participants assigned to receive placebo reported gastrointestinal symptoms with some frequency, these symptoms were more common among those assigned to receive azithromycin. However, participants who received placebo sought medical care for gastrointestinal symptoms as frequently as did those receiving azithromycin. Table 4. Symptoms Reported by Participants during the One-Year Treatment Period. Hearing loss was reported more frequently in the azithromycin group. Hearing loss was included among the symptoms discussed during the interviews because of case reports of reversible hearing loss in patients treated with high doses of azithromycin for Mycobacterium avium complex infection.13,14 Only 12 of the participants reporting hearing loss sought medical care. Two of these participants, both in the placebo group, discontinued the weekly medication (one permanently and one temporarily). Of all the participants reporting hearing loss who either permanently or temporarily stopped taking their assigned medication, six were from the azithromycin group and six were from the placebo group. Vaginal candidiasis was included among the symptoms discussed during the interviews, because it may be a side effect of long-term antibiotic treatment. Surprisingly, the symptom was more common in the placebo group, and all 12 of the women who reported receiving more than one course of treatment were from the placebo group. Thirty-four serious adverse events (12 in the azithromycin group and 22 in the placebo group) not included in Table 4 were reported to the FDA because a relation to the treatment could not be ruled out. Discussion This trial found that one year of weekly azithromycin therapy was not associated with any clinically significant benefit in the secondary prevention of coronary events. Azithromycin was associated with mild gastrointestinal symptoms. There was a greater number of reports of hearing loss in the azithromycin group, but the available data did not allow clarification of the clinical significance of these reports. More frequent vaginitis was reported in the placebo group, which is the opposite of the expected effect of long-term antibiotic treatment. It is possible that azithromycin provided therapy against bacterial vaginosis, but clinical or laboratory diagnostic data were not available. Nine other clinical trials testing antibiotics for the secondary prevention of coronary heart disease have been published.15 Of these, only the WIZARD (Weekly Intervention with Zithromax for Atherosclerosis and Its Related Disorders) trial16 was adequately powered to give a definite result. The others may be considered pilot trials because of their small sizes and short observation periods. Another deficit of most of the trials was their short treatment periods. Approximately equal numbers of the trials were reported to be positive and reported to be negative. In the WIZARD trial, azithromycin treatment was given once weekly for three months. Its results were similar to the findings of ACES, in that they also failed to support the use of antibiotic therapy for coronary heart disease. The WIZARD trial did report some antibiotic protection from events during the first six months of the trial — a result not seen in ACES. The ACES protocol required participants to have established coronary heart disease that had been stable for at least three months. Review of the study population revealed that 89 percent of patients had undergone at least one coronary revascularization procedure before the study and that more than half had angina. Most of the participants were receiving vigorous standard treatment for coronary heart disease. Events occurring during the trial might reasonably be attributed to destabilization and rupture of plaques, rather than extension of the atherosclerotic process with vessel narrowing. What do the findings of the trial tell us about the association between C. pneumoniae and atherosclerosis? Assuming that treatment was adequate, they suggest that neither C. pneumoniae nor another organism susceptible to azithromycin plays an important role in events associated with late-stage coronary heart disease. However, since ACES was not designed to study the role of C. pneumoniae in the pathogenesis of atherosclerosis, the results of the trial do not tell us anything about a possible pathogenic role of C. pneumoniae in the early development or acceleration of atherosclerosis. There have been clinical trials of antibiotic therapy directed at atherosclerotic changes in the carotid artery, peripheral arteries, and the aorta.17,18,19,20 These trials were based on noninvasive measurements of changes in the arterial wall. They did not rely on analyses of events, but measurements in the arterial wall in each subject were included in the analysis. Each trial reported that antibiotic therapy had a significantly favorable effect on the progression of disease. These positive results must be considered preliminary. However, if they can be repeated in studies with larger numbers of subjects, they will offer evidence suggesting that C. pneumoniae is involved in the pathogenesis of atherosclerotic occlusive disease. The limited data available from antibiotic treatment of atherosclerosis in animal models have shown that if the antibiotic is given shortly after the C. pneumoniae is inoculated into the lung of the animal, the effect of C. pneumoniae on the acceleration of atherosclerosis is greatly reduced or eliminated. If the antibiotic is given later, there is much less or no reduction in the acceleration of atherosclerosis caused by C. pneumoniae.21,22,23 Our study has several limitations, including the advanced stage of disease (described above), the possibility that the antibiotic does not reach the microorganism in the chronic lesions of atherosclerosis, the possibility that the treatment was not continued long enough or that the dose of antibiotic given was too small, and the possibility that the antibiotic was not sufficiently effective against C. pneumoniae. These limitations do not, for practical purposes, weaken the basic conclusion of this study that antibiotic treatment cannot be recommended for the treatment of chronic coronary heart disease. This recommendation is confirmed by the results of the PROVE IT (the Pravastatin or Atorvastatin Evaluation and Infection Therapy) trial, reported elsewhere in this issue of the Journal.24 PROVE IT did not find any significant protection from coronary events with antibiotic treatment. There were important differences between the PROVE IT trial and ACES. A different class of antibiotic, a new fluoroquinolone (gatifloxacin), was used in PROVE IT. The treatment schedule, though also prolonged, was intermittent, consisting of a 10-day course of therapy each month for a mean of 2 years. Moreover, the participants were recruited at the time of an acute coronary syndrome, and they were younger and had had less previous treatment for coronary heart disease than those in ACES. These differences broaden and strengthen the recommendation against antibiotic treatment for coronary heart disease that can be made on the basis of the ACES trial. Supported by the National Heart, Lung, and Blood Institute and Pfizer. Presented in part at the annual meeting of the European Society of Cardiology, Munich, August 30, 2004, and at the meeting of the European Society for Chlamydia Research, Budapest, Sept. 2, 2004. Dr. Grayston reports having received grant support from Pfizer for ACES. Dr. Parisi reports having equity ownership in Pfizer. Dr. Crouse reports having received consulting fees and grant support from Pfizer. Dr. Knirsch is employed by Pfizer and reports having equity interest in the company. * The Azithromycin and Coronary Events Study (ACES) investigators are listed in the Appendix. Source Information From the Departments of Epidemiology (J.T.G., L.A.J.) and Biostatistics (R.A.K.), University of Washington, Seattle; the Center for Health Studies, Group Health Cooperative, Seattle (L.A.J.); Miriam Hospital, Providence, R.I. (A.F.P.); LDS Hospital, Salt Lake City (J.B.M.); Saint Louis University Medical Center, St. Louis (J.D.C.); University of Alabama, Birmingham (W.J.R.); Wake Forest University School of Medicine, Winston-Salem, N.C. (J.R.C.); Axio Research, Seattle (S.L.B.); National Heart, Lung, and Blood Institute, Bethesda, Md. (E.S.); and Pfizer, New York (C.K.). Address reprint requests to Dr. Grayston at the Department of Epidemiology, Box 357236, University of Washington, Seattle, WA 98195. References Saikku P, Leinonen M, Mattila K, et al. Serological evidence of an association of a novel Chlamydia, TWAR, with chronic coronary heart disease and acute myocardial infarction. Lancet 1988;2:983-986. Thom DH, Grayston JT, Siscovick DS, Wang SP, Weiss NS, Daling JR. Association of prior infection with Chlamydia pneumoniae and angiographically demonstrated coronary artery disease. JAMA 1992;268:68-72. Kuo CC, Shor A, Campbell LA, Fukushi H, Patton DL, Grayston JT. Demonstration of Chlamydia pneumoniae in atherosclerotic lesions of coronary arteries. J Infect Dis 1993;167:841-849. Kuo CC, Grayston JT, Campbell LA, Goo YA, Wissler RW, Benditt EP. Chlamydia pneumoniae (TWAR) in coronary arteries of young adults (15-34 years old). Proc Natl Acad Sci U S A 1995;92:6911-6914. Jackson LA, Campbell LA, Kuo CC, Rodriguez DI, Lee A, Grayston JT. Isolation of Chlamydia pneumoniae from a carotid endarterectomy specimen. J Infect Dis 1997;176:292-295. Pathological evidence of association. In: Fong IW. Infections and the cardiovascular system: new perspectives. New York: Kluwer Academic/Plenum, 2003:139-44. Biological mechanisms and animal models. In: Fong IW. Infections and the cardiovascular system: new perspectives. New York: Kluwer Academic/Plenum, 2003:144-9. Grayston JT. Background and current knowledge of Chlamydia pneumoniae and atherosclerosis. J Infect Dis 2000;181:Suppl 3:S402-S410. Havlir DV, Dube MP, Sattler FR, et al. Prophylaxis against disseminated Mycobacterium avium complex with weekly azithromycin, daily rifabutin, or both. N Engl J Med 1996;335:392-398. Pierce M, Crampton S, Henry D, et al. A randomized trial of clarithromycin as prophylaxis against disseminated Mycobacterium avium complex infection in patients with advanced acquired immunodeficiency syndrome. N Engl J Med 1996;335:384-391. Gimenez-Sanchez F, Butler JC, Jernigan DB, et al. Treating cardiovascular disease with antimicrobial agents: a survey of knowledge, attitudes, and practices among physicians in the United States. Clin Infect Dis 2001;33:171-176. Wang SP. The microimmunofluorescence test for Chlamydia pneumoniae infection: technique and interpretation. J Infect Dis 2000;181:Suppl 3:S421-S425. Wallace MR, Miller LK, Nguyen M-T, Shields AR. Ototoxicity with azithromycin. Lancet 1994;343:241-241. Tseng AL, Dolovich L, Salit IE. Azithromycin-related ototoxicity in patients infected with human immunodeficiency virus. Clin Infect Dis 1997;24:76-77. Grayston JT. Antibiotic treatment of atherosclerotic cardiovascular disease. Circulation 2003;107:1228-1230. O'Connor CM, Dunne MW, Pfeffer MA, et al. Azithromycin for the secondary prevention of coronary heart disease events: the WIZARD study: a randomized controlled trial. JAMA 2003;290:1459-1466. Mosorin M, Juvonen J, Biancari F, et al. Use of doxycycline to decrease the growth rate of abdominal aortic aneurysms: a randomized, double-blind, placebo-controlled pilot study. J Vasc Surg 2001;34:606-610. Vammen S, Lindholt JS, Ostergaard L, Fasting H, Henneberg EW. Randomized double-blind controlled trial of roxithromycin for prevention of abdominal aortic aneurysm expansion. Br J Surg 2001;88:1066-1072. Wiesli P, Czerwenka W, Meniconi A, et al. Roxithromycin treatment prevents progression of peripheral arterial occlusive disease in Chlamydia pneumoniae seropositive men: a randomized, double-blind, placebo-controlled trial. Circulation 2002;105:2646-2652. Sander D, Winbeck K, Klingelhofer J, Etgen T, Conrad B. Reduced progression of early carotid atherosclerosis after antibiotic treatment and Chlamydia pneumoniae seropositivity. Circulation 2002;106:2428-2433. Muhlestein JB, Anderson JL, Hammond EH, et al. Infection with Chlamydia pneumoniae accelerates the development of atherosclerosis and treatment with azithromycin prevents it in a rabbit model. Circulation 1998;97:633-636. Rothstein NM, Quinn TC, Madico G, Gaydos CA, Lowenstein CJ. Effect of azithromycin on murine arteriosclerosis exacerbated by Chlamydia pneumoniae. J Infect Dis 2001;183:232-238. Fong IW, Chiu B, Viira E, Jang D, Mahony JB. Influence of clarithromycin on early atherosclerotic lesions after Chlamydia pneumoniae infection in a rabbit model. Antimicrob Agents Chemother 2002;46:2321-2326. Cannon CP, Braunwald E, McCabe CH, et al. Antibiotic treatment of Chlamydia pneumoniae after acute coronary syndrome. N Engl J Med 2005;352:1646-1654....查看详细 (28364字节)
☉ 11325849:A New Colonialism? — Conducting Clinical Trials in India
In January 2005, the government of India enacted a new rule that allows foreign pharmaceutical companies and other interested parties to conduct trials of new drugs in India at the same time that trials of the same phase are being conducted in other countries. This new rule supersedes a directive of India's Drugs and Cosmetics Rules that required a "phase lag" between India and the rest of the world. According to the old rule, if a phase 3 study had been completed elsewhere, only a phase 2 study was permitted in India. Even under the new rule, phase 1 trials will not normally be permitted in India. The old rule was designed to protect Indians from being used as guinea pigs in the testing of unproved drugs of foreign origin; trials of domestically discovered drugs were not subject to this provision. The change was made in response to vociferous demands from multinational drug companies and private organizations that conduct clinical research for a relaxation of the rules for drug trials — those necessary hurdles whose price tags can run to 40 percent of the cost of drug development.1 It has become increasingly difficult to test drugs in Western countries, with their strict regulations, elaborate safety and compensation requirements, and small populations, all of which make the recruitment of research subjects slow and expensive. Consequently, many research-based companies are now outsourcing some of their trials to Third World countries such as China, Indonesia, Thailand, and India. India is a particularly attractive site for such trials because of its genetically diverse population of more than 1 billion people who have not been exposed to many medications but have myriad diseases, ranging from tropical infections to degenerative disorders. Virtually all Indian doctors speak English, and many have acquired postgraduate qualifications abroad, primarily in Britain or the United States. Added to these attractions are cheap labor and low infrastructure costs, which can reduce expenditures for clinical trials by as much as 60 percent.2 However, even from the viewpoint of foreign drug companies, there are some major drawbacks to working in India. Sponsors do not have exclusive rights to the clinical data they generate: because trial reports are in the public domain, manufacturers of generic drugs can use the data to obtain regulatory approval of their own versions of a drug. Furthermore, the Drugs Controller General of India (DCGI) — the equivalent of the U.S. Food and Drug Administration (FDA) — is understaffed and lacks the expertise to evaluate protocols. Currently, the technical staff consists of just three pharmacists, including the controller, and not one medically qualified doctor. As a result, persistent follow-up, including personal visits to the DCGI, is required in order to push an application for a trial forward. In addition, although the country has more than half a million practicing doctors, fewer than 200 investigators have been trained in good clinical practice. Among some 14,000 general hospitals, no more than 150 have the adequate infrastructure to conduct trials, and there are fewer than a dozen pathology laboratories that meet the criteria for compliance with good laboratory practice. Only about half of the large hospitals have institutional review boards, and even these boards have not yet formulated standard operating procedures — and they, too, often lack the expertise with which to evaluate protocols. Information about conflicts of interest is neither sought nor voluntarily provided by investigators. Given the sorry state of the apparatus for reviewing proposals, the greatest concern about clinical trials in India, from the vantage point of both Indians and ethicists, is illegal and unethical trials, a number of which have attracted adverse coverage in the media in recent years. In 2002, two new chemical entities, called M4 N and G4 N, that had been discovered in the United States were tested in 26 patients with oral cancer at the government-run Regional Cancer Center in Kerala. In the same year, self-styled researchers working in their own clinics formulated "vaginal pellets" of erythromycin and tried them as contraceptive agents in more than 790 poor, illiterate, rural women in West Bengal. In 2003, letrozole, an anticancer drug, was tested in more than 430 young women at a dozen private clinics to find out whether it promoted ovulation. All these trials took place without regulatory approval. A Private, "One-Man" Clinic in New Delhi Where Letrozole Was Tested. These studies were conducted by Indian organizations, but in the past, Western pharmaceutical companies have conducted similarly unethical trials.3 Moreover, the sponsors of many such trials engage in practices that are currently legal yet ethically dubious. They have been known to offer financial inducements to participants — such as paying illiterate blue-collar workers more per month to participate in a trial than they earn at their jobs and enticing subjects by providing medication that is worth more than their annual salary. Widespread illiteracy makes it particularly easy to sidestep the standard methods of obtaining informed consent. Investigators frequently enroll patients in trials as if their participation were a necessary next step in their care. And no protocol we have ever seen has promised to continue to supply the studied medication free of charge after completion of the trial, if it is found to be beneficial. There have, of course, been some ethical and successful drug trials of immediate relevance to India and other developing countries. A notable example was a study, conducted in the early 1960s, of a new regimen for home-based treatment of tuberculosis, which was sponsored by the World Health Organization, the British Medical Research Council, and the Indian Council of Medical Research.4 Nevertheless, even as corporate sponsors, clinical research organizations, investigators, and hospitals demand easier access to Indian subjects for studies of new foreign drugs, opponents argue that India itself would not benefit greatly from these studies. The first reason it would not benefit is that the much-hyped earning potential is likely to remain a distant dream. Last year, although U.S. companies spent a total of $33 billion on new-drug research, U.S. and other Western companies combined spent only $30 million in India. Even with relaxed rules, India makes as much in one day by exporting computer software (which offers no direct risk to anyone's health) as it can in a year by offering up its citizens as study subjects. Second, according to the FDA, no more than 20 percent of the drugs introduced during the past decade have been breakthrough agents. The rest represent marginal improvements over existing therapies that are more expensive than the older drugs and are often aimed at extending the patent life of a therapy without offering any major new benefit for patients. Although this issue arises even in the developed world, it is of particular concern in countries like India — the poor in the Third World should not be used to establish the "safety and efficacy" of such products. Moreover, if trials are used to promote drugs that are more expensive but neither more effective nor safer than the standard treatments, the result is higher overall costs for health care and poor patients paying more for equivalent therapies. Third, the sponsors do not guarantee that new drugs tested in India will be made available there at affordable prices. Recent examples suggest that new patented drugs will cost so much that most Indians will not be able to buy them. For example, Eli Lilly plans to price just one 10-mg tablet of tadalafil (a treatment for erectile dysfunction) at $9 (400 rupees), which is equivalent to four days' wages for a well-paid manual worker.5 No one disputes that researchers should be encouraged to conduct Indian trials of new drugs for diseases that are endemic to this country, such as kala-azar (visceral leishmaniasis), leprosy, trachoma, tuberculosis, and water-borne diseases. But to our knowledge, hardly any trials involving such new drugs have taken place in India; globally, only 1 percent of the new drugs discovered in the past 25 years have been for tropical diseases. Moreover, even before such a limited form of "liberalization," or opening of the economy, occurs, adequate safeguards must be put in place to protect participants. Such safeguards might range from a procedure for the proper review of study protocols by the DCGI to the registration of trials and their results on publicly accessible Web sites to requirements for insurance and appropriate compensation of subjects in whom the drugs under study have adverse effects. Real informed consent should be obtained from participants in the presence of an objective third party. Trials should be conducted only by investigators trained in good clinical practice at designated research hospitals. Truly independent institutional review boards should be formed, and a system should be created to enable these boards to share information about trials they have rejected and their reasons for doing so. All projects should be carefully scrutinized for their value to the Indian people. In a population such as India's, a large proportion of the subjects in any trial will inevitably be disadvantaged persons. It is therefore of paramount importance to protect the most vulnerable — women, children, the poor, and the illiterate — by making sure that their enrollment in trials is truly voluntary and that their consent is genuinely informed. They should have access to the drug after the trial if it is found to be effective, and they should not only be treated and compensated for injury but also be compensated for any resultant loss of income. These things can be done only when the government has strengthened its regulatory system so that it is geared toward guarding the rights of patients and protecting them from exploitation. Source Information Dr. Nundy is a consultant in the Department of Surgical Gastroenterology, Sir Ganga Ram Hospital, and Dr. Gulhati is the editor of the Monthly Index of Medical Specialties — both in New Delhi, India. References Banerjee A. In full run: Clinical trials to hit Rs 1,100cr in 3 yrs. New Delhi: The Economic Times, November 17, 2004:5. Sinha G. Outsourcing drug work: pharmaceuticals ship R&D and clinical trials to India. Scientific American Online, August 16, 2004. (Accessed March 31, 2005, at http://www.sciam.com/article.cfm?articleID=00033282-DBF5-10F9-975883414B7F0000.) Gulhati CM. Needed: closer scrutiny of clinical trials. Indian J Med Ethics, January–March, 2004. (Accessed March 31, 2005, at http://www.issuesinmedicalethics.org/121ed004.html.) Lotte A, Hatton F, Perdrizet S, Rouillon A. A concurrent comparison of intermittent (twice-weekly) isoniazid plus streptomycin and daily isoniazid plus PAS in the domiciliary treatment of pulmonary tuberculosis. Bull World Health Organ 1964;31:247-271. James M. Eli Lilly gets EMR for weekend pill Cialis. New Delhi: The Economic Times, September 16, 2004:11....查看详细 (11303字节)
☉ 11325850:The Million Dollar Question
If you haven't seen Million Dollar Baby and plan to do so, stop reading. There is much to like about the film. As a father of athletic young women, I loved the physicality of the young female fighter's boxing scenes, though I live in dread of the sucker punch that can change everything. As someone who had to decide about withdrawing life support for my brother who was severely injured in a bicycling accident, I could identify with the agony felt by Clint Eastwood's trainer character as he contemplated the unthinkable — helping the now-quadriplegic former boxer to die. As a physician devoted to palliative care, which tries to maximize quality of life sometimes in the face of seemingly intolerable suffering, I have helped many patients like the boxer to find ways to keep going and find meaning in their lives again. But as an advocate for greater patient choice about end-of-life matters, I believe that such patients have a right to choose to die. In my 25 years of practice, I have helped a few patients to end their lives, sometimes secretly and sometimes openly. So what's not to like? The movie perpetuates many misconceptions that have confounded the debate about how much choice patients and their families should be given toward the end of life. I appreciated the moral agony that Eastwood's character went through and his decision that his obligation lay with his friend who could not act on her own. But the experience didn't have to be so isolating. In all 50 states, competent patients have the legal right to stop life support. All such patients should be carefully evaluated to make sure they are thinking clearly, but we in palliative care are used to having these discussions, and we can consult our psychiatrist colleagues if necessary. What most patients need is someone with whom to share their dilemma, someone who can empathize with their struggle and maintain a relationship with them while they seek ways to keep going. Many patients who have recently had a high cervical injury want to die — and later are appreciative that their caregivers were not too quick to respond to their wishes, since they subsequently adjusted to their new life. Perhaps the boxer would have found a new way to fight if she had been given a different kind of coaching at this stage. Perhaps the knowledge that she could end her life if she so desired would have made her feel less trapped — and therefore freer to keep going. Of course, a few such patients want to die despite our best efforts, and after careful medical and psychological evaluation, they are allowed to do so, humanely and out in the open, in the presence of family and health care providers — provided that they are receiving life-sustaining therapy that can be stopped. Which leads to what is probably the most important issue raised by this film: the danger of secrecy. The choice of death was carried out secretly because of ignorance about existing end-of-life options. The harm caused by her unsuccessful attempt to end her own life and the guilt, shame, and isolation that will haunt the trainer could have been avoided — or at least lessened — if knowledgeable physicians and nurses had worked with them as they faced their agonizing question. The absence of health care providers in the film should be as morally disturbing as the actions of Eastwood's character. Such considerations raise the question of how we handle mentally capable, terminally ill patients who want to die because of unacceptable suffering but who do not have life support to withdraw. In Oregon, where physician-assisted suicide is legal, such cases are handled openly, with mandatory waiting periods, second opinions, and clear documentation. Physician-assisted suicide accounts for only 1 in 1000 deaths, but 1 in 50 terminally ill patients talk to their doctors about it, and 1 in 6 discuss it with their families.1 Eighty-five percent of these patients are simultaneously enrolled in hospice programs.2 In the rest of the country, the process is handled underground, with patients and families acting on their own — sometimes unsuccessfully, other times violently, often in isolation with, at best, covert assistance from a single physician. If patients are "successful," their families are isolated with an unspeakable secret to compound their loss — much like Eastwood's character, who disappeared from his former life. Which leads to a final question: are legally regulated, open practices for these morally challenging problems safer and more predictable for patients and families than the current secret systems filled with myth and misconception? Million Dollar Baby demonstrates that secrecy around end-of-life questions has an enormous price. References Tolle SW, Tilden VR, Drach LL, Fromme EK, Perrin NA, Hedberg K. Characteristics and proportion of dying Oregonians who personally consider physician-assisted suicide. J Clin Ethics 2004;15:111-118. Oregon Department of Human Services. Physician-assisted suicide. (Accessed April 5, 2005, at http://egov.oregon.gov/DHS/ph/pas/index.shtml.)...查看详细 (5116字节)