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951.
Studies with light of the visible range had shown that light plays significant role in the biosynthesis and accumulation of citric acid in Aspergillus niger. Accumulation of 14C-labelled carbon atoms in alpha-ketoglutaric, isocitric, succinic and glycolic acids in the cultures grown under illumination suggest a probable 'shunt-metabolism' leading to the succinate-alpha-ketoglutarate-isocitrate (SKI) cycle. This shunt metabolism minimizes the accumulation of citric acid in cultures due to depletion of intermediates. 相似文献
952.
K. C. Wilhelmsen 《Cellular and molecular life sciences : CMLS》1998,54(9):920-924
Chromosome 17-linked dementias have been defined by linkage analysis. The most common of these syndromes has been estimated
to be the cause of between 2 and 20% of all dementia and has alternately been called frontotemporal dementia, Pick's disease
(without Pick bodies) and dementia lacking distinctive features [1 – 3]. The identification of the mutation responsible for
these conditions in a group of clinically and pathologically heterogeneous disorders may allow us to gain broad insight into
the processes of neurodegeneration. 相似文献
953.
In vitro differentiation of chick embryo brain cells was compared under several culture conditions. Morphological observations and acetylcholinesterase histochemical staining revealed that the development was similar in all conditions tested if cells have been derived from 7 days embryos. Considering the cultures from 11 days embryos, the cell dissociation by trypsin and the plastic surface proved to be the most favourable conditions in contrast to mechanical dissection and collagen surface. 相似文献
954.
Integrins and cardiovascular disease 总被引:2,自引:0,他引:2
Cardiovascular diseases involve abnormal cell-cell interactions leading to the development of atherosclerotic plaque, which
when ruptured causes massive platelet activation and thrombus formation. Parts of a loose thrombus may detach to form an embolus,
blocking circulation at a more distant point. The integrins are a family of adhesive cell receptors interacting with adhesive
proteins or with counterreceptors on other cells. There is now solid evidence that the major integrin on platelets, the fibrinogen
receptor α
IIb
β
3 , has an important role in several aspects of cardiovascular diseases and that its regulated inhibition leads to a reduction
in incidence and mortality due to these disorders. The development of α
IIb
β
3 inhibitors is an important strategy of many pharmaceutical companies which foresee a large market for the treatment of acute
conditions in surgery, the symptoms of chronic conditions and, it is hoped, maybe even the successful prophylaxis of these
conditions. Although all the associated problems have not been solved, the undoubted improvements in patient care resulting
from the first of these treatments in the clinic have stimulated further research on the role of integrins on other vascular
cells in these processes and in the search for new inhibitors. Both the development of specific inhibitors and of mice with
specific integrin subunit genes ablated have contributed to a better understanding of the function of integrins in development
of the cardiovascular system. 相似文献
955.
Summary In this paper, we report on the isolation and purification of the oxidase released from the roots ofLactuca sativa seedlings. This is the first time that the release of oxidases from the roots of plants into their rhizosphere has been reported. 相似文献
956.
G. Görgen C. Frößl W. Boland K. Dettner 《Cellular and molecular life sciences : CMLS》1990,46(7):700-704
Summary The terminally unsaturated hydrocarbons of the defensive secretion ofTribolium confusum are biosynthesized from fatty acids by oxidative decarboxylation. The process involves an enantiospecific cleavage of the C–H bond of thepro-(S) C(3)–H atom and simultaneous decarboxylation of the acid into an 1-alkene and carbon dioxide via ananti-periplanar transition state geometry (anti-elimination). The stereochemistry of this biotranformation is identical in all respects with the same reaction in higher plants. The mechanism seems to be of general importance for the biosynthesis of many vinylic substructures of natural products from oxygen-containing precursors. 相似文献
957.
中文文本压缩的LZW算法 总被引:8,自引:0,他引:8
本文报告两个关于中文信息处理研究的结果:(1)采用Cover的方法,猜估中文信息熵,实验表明,中文信良熵不大于4.1bits/字。(2)根据中文的结构特性,选择Welch型的Lemple-Ziv数据压缩算法,把它移植、扩展于中文文本压缩上。应用该算法于不同类型的中文文本,本文获得一些中文文本压缩实际性能值。 相似文献
958.
T. Aoyagi T. Wada M. Nagai F. Kojima S. Harada T. Takeuchi H. Takahashi K. Hirokawa T. Tsumita 《Cellular and molecular life sciences : CMLS》1990,46(1):94-97
Summary We examined the changes in the intracerebral activities, at the time of postmortem autopsy, in patients with Alzheimer's disease. When compared with the control group, the activity of kallikrein-like enzyme was significantly decreased, while prolyl endopeptidase activity increased, in the patients group. Aprotinin inhibited 50% of the activity of the former enzyme at 2×10–7M. Taken together with the results of a multivariate study, the above findings may indicate that intracerebral kallikrein deficiency plays an important role in the pathogenesis of Alzheimer's disease. 相似文献
959.
960.
None of the extracts and culture filtrates from growth of 9 races of Phytophthora infestans on living potato tissue and potato dextrose broth are toxic to chick embryos. Chloroform extracts of 4 out of 10 isolates of Alternaria solani grown on potato dextrose broth showed some toxicity to chick embryos. 相似文献