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51.
Calcitonin release from 6.23 rat medullary thyroid carcinoma C-cells was stimulated by dibutyryl cyclic AMP and inhibited by dibutyryl cyclic GMP in concentration dependent fashion. Histamine, isoproterenol, prostaglandin E2 and Bay K 8644 stimulated calcitonin release, while acetylcholine and serotonin had no significant effect on CT release. 相似文献
52.
The cytoplasmic protein GAP is implicated as the target for regulation by the ras gene product 总被引:78,自引:0,他引:78
About 30% of human tumours contain a mutation in one of the three ras genes leading to the production of p21ras oncoproteins that are thought to make a major contribution to the transformed phenotype of the tumour. The biochemical mode of action of the ras proteins is unknown but as they bind GTP and GDP and have an intrinsic GTPase activity, they may function like regulatory G proteins and control cell proliferation by regulating signal transduction pathways at the plasma membrane. It is assumed that an external signal is detected by a membrane molecule (or detector) that stimulates the conversion of p21.GDP to p21.GTP which then interacts with a target molecule (or effector) to generate an internal signal. Recently a cytoplasmic protein, GAP, has been identified that interacts with the ras proteins, dramatically increasing the GTPase activity of normal p21 but not of the oncoproteins. We report here that GAP appears to interact with p21ras at a site previously identified as the 'effector' site, strongly implicating GAP as the biological target for regulation by p21. 相似文献
53.
Dosages of either 1 or 2 mg daily of 16beta-hydroxy-dehydroepiandrosterone, given to mononephrectomized, salt-loaded female rats, had no detectable effect upon saline consumption, blood pressure, kallikrein excretion or heart and kidney weight. Its alleged mineralocorticoid properties, as judged by these criteria, were not demonstrable. 相似文献
54.
C. Gomez-Sanchez O. B. Holland C. E. Hall S. Ayachi 《Cellular and molecular life sciences : CMLS》1976,32(8):1067-1069
Summary Dosages of either 1 or 2 mg daily of 16-hydroxy-dehydroepiandrosterone, given to mononephretomized, salt-loaded female rats, had no detectable effect upon saline consumption, blood pressure, kallikrein excretion or heart and kidney weight. Its alleged mineralocorticoid properties, as judged by these criteria, were not demonstrable.This study was supported by a grant No. HL 15319 from the United States Public Health Service. 相似文献
55.
The present research brings new insights on the role of admixed corrosion inhibitors in the processes of cement hydration and rebar corrosion.The admixing of NaCl and the corrosion inhibitors in fresh mortar was found to alter the morphology and microstructure of the hardened mortar at the steel-mortar interfacial region.The admixing of the inhibitors increased the risk of carbonation of cement hydrates at the steel-mortar interfacial region,but partially displaced chloride ions. Chloride and the admixed in... 相似文献
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Nusbaum C Mikkelsen TS Zody MC Asakawa S Taudien S Garber M Kodira CD Schueler MG Shimizu A Whittaker CA Chang JL Cuomo CA Dewar K FitzGerald MG Yang X Allen NR Anderson S Asakawa T Blechschmidt K Bloom T Borowsky ML Butler J Cook A Corum B DeArellano K DeCaprio D Dooley KT Dorris L Engels R Glöckner G Hafez N Hagopian DS Hall JL Ishikawa SK Jaffe DB Kamat A Kudoh J Lehmann R Lokitsang T Macdonald P Major JE Matthews CD Mauceli E Menzel U Mihalev AH Minoshima S Murayama Y Naylor JW Nicol R 《Nature》2006,439(7074):331-335
The International Human Genome Sequencing Consortium (IHGSC) recently completed a sequence of the human genome. As part of this project, we have focused on chromosome 8. Although some chromosomes exhibit extreme characteristics in terms of length, gene content, repeat content and fraction segmentally duplicated, chromosome 8 is distinctly typical in character, being very close to the genome median in each of these aspects. This work describes a finished sequence and gene catalogue for the chromosome, which represents just over 5% of the euchromatic human genome. A unique feature of the chromosome is a vast region of approximately 15 megabases on distal 8p that appears to have a strikingly high mutation rate, which has accelerated in the hominids relative to other sequenced mammals. This fast-evolving region contains a number of genes related to innate immunity and the nervous system, including loci that appear to be under positive selection--these include the major defensin (DEF) gene cluster and MCPH1, a gene that may have contributed to the evolution of expanded brain size in the great apes. The data from chromosome 8 should allow a better understanding of both normal and disease biology and genome evolution. 相似文献
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The courtship song in Drosophila melanogaster has two components, a low-frequency hum and a train of pulses with a species-specific interpulse interval (IPI) of 30-40 ms(1,2). The IPIs oscillate rhythmically, with periods between 50 and 60 s in wild-type males(3). When females are stimulated with artificial songs in the presence of courting but silent (wingless) males, the 'pulse song' and its oscillation can enhance mating success(4?6). If separated males and females are first simultaneously primed with invariant 34-ms IPIs, their subsequent mating success is improved(7). However, exclusive prestimulation of females leads to faster mating only when the hum component of the song is applied, not constant 34-ms IPIs(5). We have re-examined these findings by testing whether prior exposure of females to a rhythmic pulse song speeds up subsequent mating performance. We report here that it does. Furthermore, learning and memory mutations(8), expressed in the females to whom songs are being played, either 'block' or attenuate the effectiveness of acoustical priming. 相似文献
60.
Video Structure Analysis 总被引:2,自引:0,他引:2
Video structure analysis is a basic requirement for most content-based video editing and processing systems. This paper presents a fast video structure analysis method based on image segmentation in each frame, with region matching between frames. The structure analysis decomposes the video into several moving objects, including information about their colors, positions, shapes, movements, and lifetimes. The method also supports user interactions to improve the results. The result shows that this method is fast and stable and can complete video analyzinq interactivelv. 相似文献