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AN Reshetilov DA Efremov PV Iliasov AM Boronin NI Kukushskin RV Greene TD Leathers 《Canadian Metallurgical Quarterly》1998,13(7-8):795-799
Amperometric biosensors register oxygen depletion in response to analyte catabolism, and thus are limited by the availability of dissolved oxygen. Microbial sensors containing immobilized cells of Gluconobacter oxydans were hyperoxygenated to 400% of control levels and the effects on sensor responses to glucose were determined. Oxygenated perfluorodecalin (a completely fluorinated organic substance) was as effective in hyperoxygenation as direct sparging with O2, increasing sensor base medium oxygen concentrations from 9.3 to 37 mg/l. Hyperoxygenation enhanced maximal biosensor response amplitudes, particularly at high cell loading densities. Maximal response rates were also improved, although less dramatically. Results suggest that hyperoxygenation may be a new general approach for modulating biosensor responses. 相似文献
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EA.hy 926 cells, a human endothelial cell line, show characteristics of differentiated endothelial cells. The cells express saturable binding of apo E-free 125I-high density lipoprotein3 (HDL3). Bmax increased from 71 to 226 ng HDL3 bound/mg cell protein after cholesterol loading of the confluent endothelial cells with cationized low density lipoprotein (LDL). The affinity did not change after cholesterol enrichment (Kd was 37 micrograms HDL3 protein/ml for control cells and 31 micrograms/ml for loaded cells). Incubation of cholesterol-loaded EA.hy 926 cells with native HDL and LDL had different effects on cellular cholesterol levels. Incubation with HDL decreased both esterified and unesterified cellular cholesterol, but LDL did not change total cellular cholesterol. However, LDL tended to increase cellular cholesteryl esters, with a concomitant decrease of unesterified cellular cholesterol. Incubation of endothelial cells with both HDL and LDL also resulted in decreased total cellular cholesterol levels. These data show that cationized LDL-loaded human endothelial EA.hy 926 cells can be used to study the net transport of cellular cholesterol to HDL, the first step in reverse cholesterol transport. 相似文献
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VA Nikolaev AN Surovaia NIu Sidorova SL Grokhovski? AS Zasedatelev GV Gurski? AL Zhuze 《Canadian Metallurgical Quarterly》1993,27(1):192-210
An analogue of netropsin has been synthesized consisting of two N-propylpyrrolcarboxamide units linked covalently to a copper-chelating tripeptide Gly-Gly-L-His by means of two and three glycine residues. Binding to DNA and synthetic polynucleotides of netropsin analogue containing three glycine residues between Gly-Gly-L-His tripeptide and the N-end of netropsin analogue (His-Nt) has been studied. It is shown that this netropsin analogue chelates a copper ion with 1:1 stoichiometry, similar to a free Gly-Gly-L-His peptide. It is found that this netropsin analogue occupies 3 to 4 base pairs upon binding to poly(dA).poly(dT) and poly[d(AT)].poly[d(AT)] polymers, irrespective of whether it binds in Cu(2+)-ligated or unligated forms. Binding constants and binding site sizes have been calculated for netropsin analogue complexes with DNA, poly(dA).poly(dT) and poly[d(AT)].poly[d(AT)] polymers at the [Cu2+]/[His-Nt] ratio equal to 0 and 1.0. In the three-component system including His-Nt and Cu(2+)-His-Nt, cooperative effects are recognized which can be explained by heterodimer generation on interaction of His-Nt and Cu(2+)-His-Nt at adjacent binding sites. 相似文献
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结合EPC工程项目管理特点,将质量管理的基本要素充分体现在每一个工作环节,确保工程质量符合规程规范和业主质量目标要求,为机组今后正常稳定运行奠定坚实的基础。 相似文献