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71.
The effect of nitric oxide (NO) donors on high-voltage-activated Ca2+ channels in insulin-secreting RINm5F cells was investigated using the patch-clamp technique in the whole-cell configuration. Sodium nitroprusside (SNP, 2-400 microM) induced a dose-dependent reduction in Ba2+ currents with maximal inhibition of 58%. The IC50 for SNP was 45 microM. A different NO donor, (+/-)S-nitroso-N-acetylpenicillamine (SNAP, 500 microM), also produced a 50% decrease in current amplitude. When 200 microM SNP was administered together with the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidozoline-1-oxyl-3-oxide (carboxy-PTIO, 300 microM), the Ba2+ current inhibition was lowered to 7%. Administration of 500 microM 8-bromoguanosine 3':5'-cyclic monophosphate sodium salt (8-Br-cGMP) mimicked the effects of SNP, causing a comparable decrease (56%) in peak-current amplitude. When soluble guanylyl cyclase was blocked by 10 microM 1H-[1,2, 4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ), the inhibitory effect of 200 microM SNP was reduced from 39% to 15%. The SNP-induced current decrease was 36% of controls after the blockade of L-type Ca2+ channels and 30% in the presence of 2.5 microM omega-conotoxin-MVIIC. These data indicate that NO inhibits both L-type and P/Q-type Ca2+ channels in RINm5F cells, probably by an increase in the intracellular levels of cGMP. NO may then significantly influence the Ca2+-dependent release of hormones from secretory cells as well as that of neurotransmitters from nerve terminals.  相似文献   
72.

Background  

Rye products have been demonstrated to lower the acute insulin demand, induce a low and prolonged blood glucose response (high Glycemic Profile, GP) and reduce subclinical inflammation. These products may therefore contribute to a lowered risk of obesity, type 2 diabetes and cardio vascular disease. The objective of the present paper was to evaluate the mechanism for a reduced postprandial insulin demand with rye products, and to explore possible appetite regulating properties.  相似文献   
73.
在一次系统故障过程中。输电线路的两套高频保护装置CSL-101B型和LFP-901B型动作行为不一致。本文就此展开分析,以达到正确理解两种保护动作行为的目的。并对加强高频保护的现场管理提出意见。  相似文献   
74.
This paper describes a tool to aid the development of computer vision applications for pixel-level diagnosis. A conceptual framework for constructing pixel processors is described. The proposed tool is based on two domains: one deals with numerical images, named features, and the other deals with symbolic images, named classes. A reduced set of image and operator types is defined. Based on it, an object-oriented language is described. The main objects define features and classes and their associated operators, namely procedures, classifiers, and rules. All system control is goal oriented and is designed to provide symbolic images as results when a request is received from a higher level of the image understanding system. Some knowledge engineering concepts, such as certainty control and instances, are also included.  相似文献   
75.
研究和讨论了图像质量评估方法,提出一种基于模糊推理的块效应评估标准。假设图像由平滑区域、边缘区域以及纹理区域等组成,而且不同的区域应采用不同的方法进行质量评估。在此基础上,给出了三个分别适用于不同区域的图像质量评估因子,并提出了一个灵活的模糊图像质量评估方法。此方法把块效应和图像本身具有的边缘分开,防止了边缘会被误认为是块效应。仿真结果表明,提出的标准对于不同的图像具有鲁棒性,有一般图像质量评价标准的性能。  相似文献   
76.
The paper describes the accurate calibration of the camera transformation for a vision system consisting of a camera mounted on a robot. The calibration includes an analysis of the linearity of the camera. A knowledge of the camera transformation allows the three-dimensional position of the object points to be determined using triangulation.  相似文献   
77.
Abstract. Although entity-relationship modelling is the most popular means of specifying the conceptual schema for the data perspective of an information system, an alternative design approach known as fact-oriented modelling appears to offer advantages. This paper provides an overview of fact-oriented modelling, including some recent revisions and an evaluation of how the method has coped with large-scale practical applications. One distinguishing feature of the approach is its emphasis on natural verbalization of information examples in terms of elementary facts. This notion of elementarity is clarified to cater for a problematic case involving compositely identified object types. Finally, the algorithm for mapping a conceptual to a relational schema is revised to cater for lazy object types.  相似文献   
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The effect of the cyclin-dependent (CDK) inhibitors olomoucine and roscovitine on cell kinetics was studied. To this end, nonsmall cell lung cancer (NSCLC) cell line MR65 and neuroblastoma cell line CHP-212 were pulse labeled with bromodeoxyuridine (BrdUrd) and chased in culture medium, to which various concentrations of olomoucine or roscovitine were added. A dose-dependent inhibition of the G1/S-phase and G2/ M-/G1 transitions was observed. Furthermore, S-phase progression was also inhibited in a dose-dependent manner. Similarly, roscovitine, another CDK inhibitor with a 10-fold higher efficiency for both CDK1 and CDK2 as compared to olomoucine, showed the same effects at a 10-fold lower concentration. At the highest tested doses both olomoucine (200 microM) and roscovitine (40 microM) induced a complete cell cycle block in both cell lines, paralleled by the appearance of apoptotic figures. In these cultures a decrease in CDK1 protein level was found as shown by Western blotting. Bivariate CDK1/DNA analysis confirmed these observations and showed that a subpopulation of cells with characteristics of apoptosis became CDK1 negative. The presented data suggest that cyclins and CDKs are involved at an important nodal point shared by pathways regulating cellular proliferation and apoptosis.  相似文献   
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