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81.
Glutathione (GSH) is important in maintaining intracellular thiol status. The present study looked at the effect of GSH depletion on lipid composition of colon-derived HT-29 cells. GSH was depleted in HT-29 cells by incubation either with buthionine-S, R-sulfoximine (BSO) or diethylmaleate (DEM). GSH was restored during early periods of cells growth by supplementation of growth medium with either GSH ester or N-acetyl cysteine (NAC). Lipids were analysed following GSH depletion and supplementation. Among the neutral lipids, an increase in free cholesterol and diacylglycerol and decrease in cholesteryl ester and triacylglycerol were seen in GSH-depleted cells as compared to control cells. There were no detectable free fatty acids either in control or GSH-depleted cells. Among the phospholipids, a decrease in phosphatidylcholine and phosphatidylinositol and an increase in phosphatidylethanolamine were observed. These changes were a completely reversed by supplementation of BSO-treated cells with GSH ester and partially reversed by N-acetyl cysteine. These results suggest that the GSH status of the cell plays an important role in the lipid composition of the cells. 相似文献
82.
M Viswanathan E Scalbert P Delagrange B Guardiola-Lema?tre JM Saavedra 《Canadian Metallurgical Quarterly》1997,8(18):3847-3849
Melatonin receptors are expressed in the cerebral arteries of the rat which form the circle of Willis. We report here that melatonin induces contraction of in vitro preparations of pressurized rat posterior communicating artery, in a concentration-dependent manner. This action of melatonin is inhibited by S-20928, a specific melatonin receptor antagonist. Our results demonstrate that the contractile action of melatonin is mediated by its receptors in the cerebral artery, and suggest a role for melatonin in the regulation of cerebral circulation. 相似文献
83.
Thin-film capacitors of erbium fluoride were fabricated by electron beam gun deposition. The current-voltage characteristics of the erbium fluoride films were studied in the temperature range 323 to 396 K. For sufficiently high electric fields (>104 V cm–1), the leakage current increases exponentially with the square root of the applied field. Analysis of the data suggests an electrode-limited mechanism such as that suggested by Schottky. It is seen that the conduction mechanism is an activated process with the activation energy decreasing with increasing field. 相似文献
84.
A method for predicting multimodal behaviour in nonlinear systems with narrowband Gaussian inputs is described. The technique is applicable when the nonlinearity is a function of the input and its derivatives. 相似文献
85.
86.
K. R. Paramasivam M. Radhakrishnan C. Balasubramanian 《Journal of Materials Science》1981,16(5):1183-1186
The current-voltage characteristics of thin-film capacitors with evaporated terbium fluoride dielectric have been studied as a function of temperature (in the range 300 to 418 K). For sufficiently high electric fields (> 104 V cm–1, the leakage current is found to increase exponentially with the square root of the applied electric field. Analysis of the data suggests an electrode-limited mechanism such as that suggested by Schottky. It is seen that the conduction mechanism is an activated process with the activation energy decreasing with increasing field. Dielectric break-down and its dependence on film thickness have also been investigated. Break-down field strength follows the Forlani-Minnaja relation. 相似文献
87.
Summary Polyestermaleamides have been synthesized from N,N-bisisomaleimide, p-aminophenol, iso-and tere-phthaloyl chlorides. Through ring-opening addition reaction, a bisphenolamide was first formed; it was then polycondensed with acid chlorides to produce Polyestermaleamides, with an ordered sequence. The polymers were fully characterized by elemental analysis, infrared and electronic spectra, solubility in various solvents as well as inherent viscosity measurements. Thermal behaviour of the polymers were determined by thermogravimetric analysis in nitrogen atmosphere. 相似文献
88.
Computer data processing and electronic monochromatization of x-rays were employed for determining crystallinity, disorder parameter, Hermans' orientation factor, as well as DeLuca and Orr spiral angle of native, mercerized and urea-treated cottons. The results indicate the values for the degree of crystallinity to vary significantly between ecttons. Increase in disorder on mercerization is confirmed. The effect of urea treatment is not so well defined. The differences in Hermans' x-ray orientation factor are significant at the 1% level between cottons and at the 10% level between treatments. Besides, from a critical analysis of the values obtained, it is shown that the spiral angle φt in the method of DeLuca and Orr is probably a direct estimate of the mean inclination of the crystallites to the fiber axis, while Hermans' orientation angle β is a complex function of other parameters as well. The computer programs which could be applied to other polymers are included. 相似文献
89.
It is shown by an ac calorimetry technique that the multiple heat capacity anomalies which occur below the superconducting transition temperature for small polycrystalline Nb3Sn samples are intrinsic to these samples. The recent suggestions that shear stresses can account for these results are analyzed for their validity. The dependence of the occurrence of these multiple anomalies upon the thermal history of the samples was investigated.Supported in part by U.S. Atomic Energy Commission under the Contract No. USAEC-AT-(04-3)-34 at the Department of APIS, UCSD, La Jolla, California. Present work supported under the auspices of ERDA.Supported by Air Force Office of Scientific Research, Air Force Systems Command USAF, under AFOSR Contract No. AFOSR/F-44620-72-C-0017. 相似文献
90.
D. O. Welch C. S. Pande R. Caton R. Viswanathan 《Journal of Low Temperature Physics》1983,52(3-4):289-300
The available data on the effect of neutron and α-particle irradiation on the superconducting properties and the low-temperature specific heat capacity of single- and polycrystalline V3Si were analyzed in a unified manner. It was found that the electron-phonon renormalization parameter λ does not vary simply proportionally to the bare density of electron states at the Fermi level as had been earlier conjectured by Dynes and Varma, nor does it vary in exactly the same manner as found by Fradin and Williamson to hold for a variety of vanadium-based A15 structure compounds and pseudobinary alloys. When the behavior of V3Si is compared with that of Nb3Sn, Nb3Al, and Nb3Ge, it is seen that the response to disorder of parameters of importance in the superconductivity of these compounds does not follow any simple, universal behavior. 相似文献