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排序方式: 共有121条查询结果,搜索用时 15 毫秒
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Hiroshi Morita Yuichiro Tomizawa Jun Deguchi Tokio Ishikawa Hiroko Arai Kazumasa Zaima Takahiro Hosoya Yusuke Hirasawa Takayuki Matsumoto Katsuo Kamata Wiwied Ekasari Aty Widyawaruyanti Tutik Sri Wahyuni Noor Cholies Zaini Toshio Honda 《Bioorganic & medicinal chemistry》2009,17(24):8234-8240
Cassiarin A 1, a tricyclic alkaloid, isolated from the leaves of Cassia siamea (Leguminosae), shows powerful antimalarial activity against Plasmodium falciparum in vitro as well as P. berghei in vivo, which may be valuable leads for novel antimalarials. Interactions of parasitized red blood cells (pRBCs) with endothelium in aorta are especially important in the processes contribute to the pathogenesis of severe malaria. Nitric oxide (NO) reduces endothelial expression of receptors/adhesion molecules used by pRBC to adhere to vascular endothelium, and reduces cytoadherence of pRBC to vascular endothelium. Cassiarin A 1 showed vasorelaxation activity against rat aortic ring, which may be related with NO production. A series of a hydroxyl and a nitrogen-substituted derivatives and a dehydroxy derivative of 1 have been synthesized as having potent antimalarials against P. falciparum with vasodilator activity, which may reduce cytoadherence of pRBC to vascular endothelium. Cassiarin A 1 exhibited a potent antimalarial activity and a high selectivity index in vitro, suggesting that the presence of a hydroxyl and a nitrogen atom without any substituents may be important to show antimalarial activity. Relative to cassiarin A, a methoxy derivative showed more potent vasorelaxant activity, although it did not show improvement for inhibition of P. falciparum in vitro. These cassiarin derivatives may be promising candidates as antimalarials with different mode of actions. 相似文献
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Shiro Okumura Tetsuyuki Akao Satoko Yamashita Tokio Ichimatsu Kuniyo Inouye 《Cytotechnology》2005,47(1-3):59-67
Proteins of plasma membrane could be an index of purification of the plasma membrane of animal cells. A convenient method
is proposed for determining the plasma membrane proteins by a surface plasmon resonance (SPR) biosensor. Biotinylated proteins
were observed only in the peripheral areas of MOLT-4 cells which were treated by 5-[5-(N-succinimidyloxycarbonyl) pentylamido] hexyl-d-biotinamide. The proteins on HeLa cells were also biotinylated. And then the membrane samples of the HeLa cells were injected
onto the avidin-immobilized SPR-surface, and components bound non-specifically on the surface were removed by a washout solution.
The amount of biotinylated protein (BP) was determined directly from the absolute resonance unit (RU) after injection of the
washout solution. In the method a reference surface was not needed. The amount of BP bound to the surface was gradually attenuated
with the repeated injection, and a method for calibrating the RU value was introduced by considering the ratio of attenuation
by every injection. The correlation between the BP titer calculated by the calibration and the theoretically-estimated one
was greatly improved. Three cycles of the BP determination on a sensor surface was performed successfully. During the purification
process of membrane fractions, the degree of purification as judged by the BP titer was in good agreement with the degree
of increase in aminopeptidase N activity in the membrane fraction. Thus, the BP titer could be used as an index for purification
of plasma membrane. 相似文献
5.
We examined the relationship between body size of the riparian spider Nephila clavata and the contribution of allochthonous (aquatic insects) and autochthonous (terrestrial insects) sources to its diet using
stable isotope analysis. During the study period from July to September, the body size of the females increased remarkably
(about 60-fold) but that of males remained small. The biomass of both aquatic and terrestrial insects trapped on the spider
webs increased with spider size, with the biomass of the former ranging between 30 and 70% of that of the terrestrial insects.
The average relative contribution of aquatic insects to the diet of the spiders, calculated from δ13C values, was 40–50% in spiders in the early juvenile and juvenile stages, 35% in adult males and 4% in adult females. There
was a significant negative relationship between the relative contribution of aquatic insects and body size of the female spiders.
We conclude that aquatic insects might be an important seasonal dietary subsidy for small spiders and that these allochthonous
subsidies may facilitate the growth of riparian spiders, which may in turn enable the spiders to feed on larger prey. 相似文献
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After inhibiting DNA synthesis in Escherichia coli, repeated cycles of chromosome replication can occur in the absence of protein synthesis. This “stable” replication requires the products of all of the known dna genes.Stable replication results from inhibiting DNA synthesis by treatment with naladixic acid, cytosine arabinoside or hydroxyurea; or by placing dnaB, dnaE or dnaG mutants at non-permissive temperatures. It also follows a “shift-up” into rich medium in which RNA and protein are synthesized more rapidly than DNA. Paradoxically, stable replication is induced also by treatment with concentrations of streptolydigin which do not inhibit DNA replication but temporarily and partially inhibit RNA and protein synthesis. During all of these treatments, some protein synthesis must occur.Stable replication is not immediately expressed after a short period of thymine starvation or streptolydigin treatment, but requires a subsequent period of protein synthesis. Once established, however, the stable replication state is permanent and will persist in the absence of protein synthesis or during normal growth.After stable replication has been determined by a period of DNA inhibition, it is possible to inactivate replication by heating dnaA, B, C, E and G temperature-sensitive mutants. However, resynthesis of these gene products in the presence of thymine and at the permissive temperature restores stable replication activity. Since restoration of activity can occur under normal growth conditions which do not induce stable replication, it was concluded that the dnaA, B, C, E and G gene products do not directly determine the stabilized character of the replication fork.A model is presented which attempts to explain the ability of different treatments to induce stable replication. 相似文献
7.
The Endemic Fritillaria Species of Japan 总被引:1,自引:0,他引:1
Summary. This paper reviews and illustrates the seven known species of Fritillaria subgenus Fritillaria that are endemic to Japan and describes a new, eighth species, Fritillaria tokushimensis Akasawa, Katayama et Naito. A key for their identification is provided. 相似文献
8.
Nonselective Incorporation into Sporangium of Either “Older” or “Younger” Chromosome of the Vegetative Cell During Sporulation in Bacillus cereus 下载免费PDF全文
Employing Bacillus cereus strain 2, we examined the fate of two chromosomes contained in vegetative cells in the course of sporulation. Cytological observations and quantitative estimation of deoxyribonucleic acid (DNA) confirmed the earlier observations that, during the course of sporulation, one of two chromosomes of the vegetative cell was incorporated into the sporangium and the other disappeared into the medium as the result of cell lysis. Log-phase cells, labeled completely with thymine-2-(14)C in the presence of deoxyadenosine, were cultured in the "cold" glucose-glutamate-glycine-salts medium, and culture samples, taken at intervals at successive generations, were subjected to sporulation in glutamate-salts medium. The percentage of radioactivity in the spores separated from each culture remained almost unchanged at nearly 50% and was independent of the number of generations of the preceding culture in the "cold" medium. This suggests that the selective incorporation into the sporangium of either the "older" or "younger" chromosome of a vegetative cell does not occur in the course of spore formation. Some examples of the selective and nonselective behavior of DNA molecules in cellular events in microorganisms are cited. 相似文献
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