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991.
To ensure the highest quality of care for patients, surgeons must have the most up-to-date information on the intraocular lenses (IOLs) they implant. This registry presents the lens constants (A constant, anterior chamber depth, and surgeon factor) for all commercially available IOLs--869 lenses from 22 manufacturers. The constants will be updated every January.  相似文献   
992.
OBJECTIVE: To collect the ratings of American rheumatologists regarding relative short-term and long-term effectiveness of disease-modifying antirheumatic drug (DMARD) therapy in the treatment of rheumatoid arthritis and to compare these data with results of a meta-analysis of randomized, controlled clinical trials (RCTs) of these drugs. METHODS: A survey was mailed to 3,200 United States rheumatologists who were members of the American College of Rheumatology during the summer of 1996. The survey was completed by 645 rheumatologists. RESULTS: Methotrexate (MTX) was rated as substantially more effective than any other DMARD after both 1 year and 4 years of therapy. At 1 year, more than 90% of rheumatologists rated MTX as "good or excellent," compared with 35% giving a similar rating to intramuscular (IM) gold, the second-ranked DMARD. At 4 years, MTX was rated as "good or excellent" by 65%, compared with 53% for combinations, 30% for prednisone, and 11% for hydroxychloroquine, the second-ranked single DMARD. These ratings reflect results of long-term observational studies, but differ considerably from a meta-analysis of results of short-term RCTs, in which the efficacy of MTX, sulfasalazine, penicillamine, and IM gold were indistinguishable. CONCLUSION: The ratings of US rheumatologists regarding effectiveness of DMARD therapies are in agreement with observational data, but differ substantially from results of RCTs. These findings suggest that observational studies may yield useful and important information about treatment results, which are complementary to, but not available from, the RCT model. Regulatory agencies should consider long-term observational studies as a part of the evaluation of drugs.  相似文献   
993.
The Pacinian corpuscle (PC) is composed of an afferent neurite surrounded by an accessory capsule formed by concentric layers of lamellae. Projecting from the neurite, which is elliptical in cross-section, are "filopodia" or axonal, spike-like extensions. These filopodia are the putative sites of transduction. It has been proposed that two populations of filopodia organized in morphofunctional opposition exist, and that this arrangement is responsible for the bidirectional sensitivity of PCs as seen in receptor potential recordings. In order to explore this possibility, PCs obtained from cat mesentery were processed for electron microscopy, and semiserial reconstructions were made. We evaluated the extensions' (n > 110) locations, inclusions, shapes, and sizes. The filopodia were found to project along the major elliptical axis of the neurite, their density being approximately 2.8 per micron. The filopodia were found to contain filaments, vesicles, and amorphous ground substance, and dense accumulations of mitochondria were found at their bases. Measurements of their size (i.e., length, width, and height) suggest that there are two different types of filopodia. No other obvious relations among filopodial type, location along the neurite, and landmarks for transduction were found. The presence of the two filopodial types may be the basis for the bidirectional sensitivity of the PC.  相似文献   
994.
The non-stationary noise generator of a large-signal IMPATT oscillator is studied. It is shown that only the zeroth-order term of the series expansion of the autocorrelation for the noise voltage is of importance for the oscillator noise spectrum. The zeroth-order term is determined by an integral of the square of the Green's function for the total voltage from a generation of a pair of carriers weighted by the mean generation rate

A PIN diode model with a fixed rectangular voltage is studied numerically. The short-circuit noise current is shown to be inversely proportional to the reverse saturation current,Js. The possibility of improving the noise properties by increasing Js is discussed.  相似文献   
995.
OBJECTIVE: To assess the incidence of lupus anticoagulant (LAC) in patients with peripheral vascular disease. DESIGN: Prospective clinical study. SETTING: University Hospital. MATERIALS: 20 patients with claudication (group 2), 20 patients with critical ischaemia (group 3) and 20 patients prior to elective abdominal aortic aneurysm surgery (group 4) were compared to 20 general surgical controls (group 1). CHIEF OUTCOME MEASURES: Venous blood samples for coagulation assay. MAIN RESULTS: Positive results for LAC by the Dilute Russell's viper venom time (DRVVT) with the platelet neutralisation procedure were present in 26 out of 60 vascular patients compared with none of the 20 general surgical controls. The three vascular groups showed a similar prevalence of LAC and this differed significantly from that in the control group (chi 2 = 10.94, p = 0.0009). Of the 26 positive results only three were associated with an abnormal activated partial thromboplastin time (APTT), which has previously been used as a marker for the presence of LAC activity. Fibrinogen levels were raised in seven of 20 patients in group 2 but were normal in the remaining vascular groups (p = 0.001). The mean factor VII level (124.1 units dl-1) in group 2 was higher than the mean of the remaining vascular patients (109.3 units dl-1, p < 0.05). CONCLUSIONS: The high prevalence of LAC in patients with peripheral vascular disease and the associated increased risk of early graft thrombosis may justify routine testing by DRVVT prior to reconstructive vascular surgery. Treatment of these patients with antiplatelet agents or formal anticoagulation perioperatively should be considered.  相似文献   
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