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Recent studies using anion exclusion chromatography have suggested that uracil is misincorporated into the DNA of patients with megaloblastic anemia to levels detectable by nonradioactive methods. We have investigated the nucleotide composition of DNA from the bone marrow mononuclear cells of eight patients with cobalamin deficiency and compared this with that found in normal subjects. The median level of uracil in the megaloblastic group was 0.082 mol% of cytosine (approx. 0.02 mol% of all bases in DNA), which was similar to that found in the control group (median 0.085 mol% of cytosine) and may be attributable, at least in part, to artefactual deamination of deoxycytidine monophosphate during the DNA hydrolysis. Our findings give no support for the view that, by overwhelming the uracil N-glycosidase mechanism, the degree of uracil misincorporation in megaloblastic anemia is sufficient to increase the steady state level of uracil in the DNA by amounts detectable by nonradioactive methods. Using high performance liquid chromatography, we have also demonstrated normal levels of methylcytosine in the DNA of megaloblastic subjects. 相似文献
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The hypothesis that the neural foramina in some patients are critically narrowed by axial compression of the spine has not been studied with direct imaging techniques. Frozen cadaveric motion segments of the lumbar spine (intervertebral disk and contiguous vertebrae) were imaged with computed tomography (CT). The segments were thawed and compressed in a hydrostatic press to simulate axial loading, and then the segments were frozen and imaged again. The motion segments were subsequently sectioned with a cryomicrotome, and the chronic degenerative changes present in the disks were classified. Pre- and post-compression CT images were compared, and anatomic relationships were studied. In 41 randomly selected segments (some with preexisting radial, transverse, and concentric annular tears), compression diminished the diameters and cross-sectional areas of the spinal canal and neural foramina. In no cases were nerve roots displaced, distorted, or compressed by axial loading. This study suggests that axial loading, such as that produced by ordinary weight bearing, does not critically compromise the neural foramina even in the presence of chronic degenerative disk changes. 相似文献
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Failure by the world dialysis community to understand and use the dry-weight method of blood pressure (BP) control has resulted in an increasing incidence of treatment-resistant hypertension, which remains the principal cause of cardiovascular morbidity and mortality. This failure may in part be because the relationship between the extracellular volume (ECV) and BP is not simple and linear, but complex, because of a lag of several weeks between the normalization of the time-averaged ECV and the decrease in BP. Another cause for this failure may be the unwillingness to taper and stop all antihypertensive medications during the transition from hypertension to normotension. In this report, we describe in detail the lag phenomenon, document its presence during treatment in other populations, and describe how this knowledge is used in the application of the dry-weight method of drug-free BP control in the dialysis population. 相似文献
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Design and preliminary evaluation of an expert system for platelet request evaluation 总被引:1,自引:0,他引:1
In spite of growing awareness of the potential risks associated with transfusion, the number of platelet units transfused in the United States continues to increase each year. There is a growing interest in ensuring that all transfusions are administered for appropriate reasons. Prospective review of requests for transfusions has been used to accomplish this goal. Although successful in reducing the number of inappropriate transfusions, this review method requires great time commitments by blood bank personnel and physicians. A knowledge-based system (ESPRE) that aids hospital blood bank personnel in the review of requests for platelet transfusions has been developed. The system automatically obtains most of the required patient data via a direct link to the hospital's main laboratory computers. The system generates a printed report that includes a list of patient-specific data, a list of the conditions for which a transfusion would be appropriate for the particular patient (given the clinical condition), and the conclusions drawn by the system. During a preliminary clinical evaluation of ESPRE, 73 randomly selected platelet transfusion requests were evaluated for approval by laboratory personnel and ESPRE. Overall, ESPRE would have approved 71 of the requests and laboratory staff would have approved 72. Forty-four percent of the requests would have been approved for the same reasons given by the staff. There were only three disagreements on final approval between ESPRE and blood bank personnel. This computerized expert system is a promising approach to the prospective review of all platelet transfusions. 相似文献
100.
Interventions for preventing falls in elderly people 总被引:4,自引:0,他引:4
LD Gillespie WJ Gillespie MC Robertson SE Lamb RG Cumming BH Rowe 《Physiotherapy》2003,89(12):692-693