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171.
R Eshel M Firon BZ Katz O Sagi-Assif H Aviram IP Witz 《Canadian Metallurgical Quarterly》1995,44(2-3):209-212
Ouabain-induced changes of the free cytoplasmic Na+ concentration ([Na+]i) were monitored in aggregates of cells prepared from beta-cell-rich pancreatic mouse islets and the results were compared with the total islet content of sodium. The steady-state [Na+]i was lower in 20 mM glucose (11 mM) than in 3 mM glucose (14 mM). In the presence of 3 mM glucose the addition of 1 mM ouabain resulted in a rise in [Na+]i with an initial rate of 1.5 mM/min. However, the increase of total sodium corresponded to 2.8 mM/min, suggesting that rapid binding and/or sequestration of Na+ are prominent features for pancreatic beta-cells. Elevation of the glucose concentration to 20 mM increased the rate of ouabain-dependent rise of [Na+]i. The effect of glucose was mimicked by 1 mM tolbutamide or 100 microM carbachol and was counteracted by 100 nM of the alpha 2-adrenergic agonist clonidine. Glucose also accelerated the lowering of [Na+]i after withdrawal of ouabain. In promoting not only the entry but also the extrusion of Na+, glucose actually enhances the turnover of the ion in pancreatic beta-cells. 相似文献
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In experiments with a primary culture of adrenal cells, it has been studied the influence of chloditane, as a specific inhibitor of adrenocortical function, on the synthetic processes in the newborn pig adrenal cells, whose organ and cell cultures are more and more used as transplantation material for the treatment of adrenal insufficiency. It has been shown that incubation of adrenocorticocytes with chloditane (final concentration in culture medium: 1 to 10,000 ng/ml) during 24 hours had a marked negative dose-dependent effect on the indices of inclusion of 3H-thymidine and 3H-uridine into the nucleic acids. In the presence of a maximum chloditane concentration, inclusion made, respectively, 16.9 and 46.0% from control. A trustworthy effect of chloditane on the indices of 3H-leucine inclusion (protein synthesis) has been established only for concentration 10 to 100 ng/ml and made near 70% from control. It has been discussed a possible mechanism of chloditane action on the synthetic processes in adrenal cells. 相似文献
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AG Khomenko KV Ozerova VV Romanov KM Bugrova IP Zaitseva AI Dobychina IG Zankisova LP Mikheeva 《Canadian Metallurgical Quarterly》1996,(6):64-68
Based on the follow-up of 1,600 patients with sarcoidosis from 1971 to 1996, the authors analyzed the value of various methods for identifying the disease, the frequency and nature of misdiagnoses. They showed the efficiency of basic treatments in patients with sarcoidosis: corticosteroidal hormones, nonhormonal antiinflammatory drugs, plasmapheresis, and physiotherapy. Recurrencies and progression were seen in 23.85% of patients. The likely causes of recurrent sarcoidosis are considered. It is concluded that recurrencies are one of the important problems of modern sarcoidosis. 相似文献
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The problem of epoch selection in frequency analysis of biomedical signals often involves tradeoffs between the physiological system studied stationarity, the spectral resolution required, the need for dynamic investigations implying shorter epochs, etc. The accuracy of the spectra strongly depends on the epoch length. We propose a method for optimal epoch selection introducing the notion of 'quality of power spectra'. Two criteria for quantitative estimation of spectral quality are defined, considering a quality to be high when more power is concentrated in narrow frequency bands. A synthesized signal is used for describing the procedure developed and evaluating the accuracy. Noise sensitivity is assessed by adding intensive noise to the signal. Hundreds of synthesized signals are used for validation of the method and some initial experiments with heart rate variation data are presented. 相似文献
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