共查询到20条相似文献,搜索用时 9 毫秒
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J H Young 《The Yale journal of biology and medicine》1980,53(6):555-566
Throughout the nineteenth century, physicians assumed the major task of analyzing and warning against quackery and unorthodoxy. The nature of this criticism is described, with key reliance on Worthington Hooker's Lessons from the History of Medical Delusions (1850). Most physicians viewed prospects for suppressing quackery more hopefully than Hooker did. Even he, however, would be shocked that delusion could persist so stubbornly despite advancing medical science, expanding education, and increasing regulation. Many factors help explain today's continuing-even burgeoning-quackery. These include a less cheerful view of both human nature and of the future, widespread skepticism about the fruits for science, impatience with governmental regulation, the vogue for self-help in health, increasing promotional sophistication on the part of unorthodox health vendors, and cooperation among various wings of unorthodoxy to maximize political pressure. Examples are given. Champions of alternative therapies predict their triumph over orthodox medical science in the contest being waged for the allegiance of the public. 相似文献
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Smith KA 《Medical immunology (London, England)》2004,3(1):3
In the past 50 years, immunologists have accumulated an amazing amount of information as to how the immune system functions. However, one of the most fundamental aspects of immunity, how the immune system discriminates between self vs. non-self, still remains an enigma. Any attempt to explain this most intriguing and fundamental characteristic must account for this decision at the level of the whole immune system, but as well, at the level of the individual cells making up the immune system. Moreover, it must provide for a molecular explanation as to how and why the cells behave as they do. The "Quantal Theory", proposed herein, is based upon the "Clonal Selection Theory", first proposed by Sir McFarland Burnet in 1955, in which he explained the remarkable specificity as well as diversity of recognition of everything foreign in the environment. The "Quantal Theory" is built upon Burnet's premise that after antigen selection of cell clones, a proliferative expansion of the selected cells ensues. Furthermore, it is derived from experiments which indicate that the proliferation of antigen-selected cell clones is determined by a quantal, "all-or-none", decision promulgated by a critical number of cellular receptors triggered by the T Cell Growth Factor (TCGF), interleukin 2 (IL2). An extraordinary number of experiments reported especially in the past 20 years, and detailed herein, indicate that the T cell Antigen Receptor (TCR) behaves similarly, and also that there are several critical numbers of triggered TCRs that determine different fates of the T cells. Moreover, the fates of the cells appear ultimately to be determined by the TCR triggering of the IL2 and IL2 receptor (IL2R) genes, which are also expressed in a very quantal fashion. The "Quantal Theory" states that the fundamental decisions of the T cell immune system are dependent upon the cells receiving a critical number of triggered TCRs and IL2Rs and that the cells respond in an all-or-none fashion. The "Quantal Theory" accounts fully for the development of T cells in the thymus, and such fundamental cellular fates as both "positive" and "negative" selection, as well as the decision to differentiate into a "Regulatory T cell" (T-Reg). In the periphery, the "Quantal Theory" accounts for the decision to proliferate or not in response to the presence of an antigen, either non-self or self, or to differentiate into a T-Reg. Since the immune system discriminates between self and non-self antigens by the accumulated number of triggered TCRs and IL2Rs, therapeutic manipulation of the determinants of these quantal decisions should permit new approaches to either enhance or dampen antigen-specific immune responses. 相似文献
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I Oswald 《BMJ (Clinical research ed.)》1979,1(6172):1167-1168
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A. N. Charney 《The Yale journal of biology and medicine》1996,69(4):329-335
Only minimal quantities of ingested and normally secreted solutes and water are excreted in the stool. This near 100% bioavailability means that the diet and kidneys are relatively more important determinants of solute, water and acid-base balance than the intestine. Intestinal bioavailability is based on excess transport capacity under normal conditions and the ability to adapt to altered or abnormal conditions. Indeed, the regulatory system of the intestine is as complex, segmented and multi factorial as in the kidney. Alterations in the rate and intestinal site of absorption reflect this regulation, and the diagnosis and treatment of various clinical abnormalities depend on the integrity of intestinal absorptive processes. However, the basis for this regulation an bioavailability are uncertain. Perhaps they had survival value for mammals, a phylogenic class that faced the twin threats of intestinal pathogens and shortages of solutes and water. 相似文献
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In recent years, a number of studies have been performed to evaluate the possible health benefits of an increased intake of folic acid (FA) on human health. However, the only well-documented benefit emerging from randomized controlled trials, nonrandomized interventions trials, and observational studies is the risk reduction of neural tube defects (NTDs). NTDs are congenital malformations that include anencephaly, encephalocele, and spina bifida caused by the failure of fusion of the neural tube that normally closes between 22nd and 28th day since conception (on an average 40-42th day after the first day of last menstrual period). The occurrence of NTDs varies among population between 0.8 and 3 per 1,000, and it is estimated that 324,000 pregnancies are affected every year worldwide. More FA can decrease the NTDs risk up to 0.6 per 1,000 births. Other malformations as congenital heart defects, cleft lip, and limb deficiencies can be most probably also reduced. To decrease the NTDs risk, it is recommended that all women capable of becoming pregnant should have more FA. The goal is that every woman could start her pregnancy with an optimal folate status, estimated today to be as more than 906 nmol/L of red blood cell folate concentration. More FA can be obtained through a strict Mediterranean pattern of nutrition and healthy life style, fortified food, supplements. Women and health authorities can choose the most appropriate strategy. Monitoring folate status of women during the periconceptional period is an essential way to evaluate the success of the preferred strategy. 相似文献
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R M Goldwyn 《Plastic and reconstructive surgery》1990,85(3):430-431
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《Clinical eye and vision care》1998,10(1):17-20
The recent literature describing the relationship between the choroidal blood flow and glaucoma is reviewed. Color Doppler imaging, fundus pulsation amplitudes, videoangiographic studies and scanning laser Doppler flowmetry are examined. 相似文献
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D Parsons 《BMJ (Clinical research ed.)》1993,306(6872):253-255
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