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排序方式: 共有117条查询结果,搜索用时 15 毫秒
21.
Koichi Iwasaki Steven A. Toms Gene H. Barnett Melinda L. Estes Manjula K. Gupta Barbara P. Barna 《Cancer immunology, immunotherapy : CII》1995,40(4):228-234
We reported previously that tumor necrosis factor α (TNFα) inhibited proliferation and invasiveness of human malignant glial cells. Because tamoxifen, an estrogen antagonist, has also been shown to inhibit growth of such cells, we hypothesized that a combination of tamoxifen and TNFα might be more effective than either reagent alone. TNFα (1–100 ng/ml) or tamoxifen (80 ng/ml-2 μg/ml) alone inhibited proliferation of a human glioblastoma cell line (WITG3) in a dose-dependent fashion; in combination, tamoxifen and TNFα yielded additive growth inhibition. Apoptotic cells characterized by nuclear fragmentation were detectable after 48 h of TNFα or tamoxifen exposure and were significantly increased by combination treatment. In non-neoplastic human astroglia and fibroblasts, proliferation was unaffected by tamoxifen, and enhanced by TNFα as previously reported. Staurosporine (2–50 nM), which has been reported to augment the effects of TNFα, was less effective than tamoxifen against WITG3 and, in addition, was markedly inhibitory to non-neoplastic glial cells. Binding studies yielded no evidence of WITG3 estrogen or progesterone receptors, nor of tamoxifen effects on TNFα receptors. Data suggest that TNFα and tamoxifen in combination display growth-regulatory properties, which (a) are more inhibitory to human glioblastoma cells than either agent alone, (b) do not affect non-neoplastic glia, (c) do not require either estrogen/ progesterone receptors or alteration of external TNFα receptors, and (d) may involve apoptosis. 相似文献
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23.
Human microvascular endothelial cell-extracellular matrix interaction in cellular growth state determination 总被引:3,自引:0,他引:3
S. R. Mallery L. E. Lantry M. C. Toms L. C. Titterington B. L. Hout G. P. Brierley R. E. Stephens 《Cell and tissue research》1995,279(1):37-45
We introduce two methods, both of which are based on cellular-extracellular matrix interaction, which will facilitate the study of human microvascular endothelial cells. One method describes the means to obtain a G1 population baseline in human microvasclular endothelial cells. Because of the contribution of the extracellular matrix in endothelial cell growth, synchronization in G1 was possible only after the incorporation of angiostatic levels of heparin and hydrocortisone into the extracellular matrix. In the second method, we demonstrate that selective perturbation of human microvascular endothelial cell-extracellular matrix interactions results in the induction of a transitional growth state, between proliferative and differentiated growth states, in human microvascular endothelial cells. In the functional, microtubule formation assays, transitional growth state endothelial cells display rates that are indermediate between those obtained from differentiated and proliferative endothelial cells. Our results demonstrate the importance of the human microvascular endothelial cell-extracellular matrix interaction in the determination of cellular growth state. Our findings also imply that responsiveness of microvascular endothelial cells to their cellular-extracellular matrix environs is highest during the differentiated growth state. 相似文献
24.
Background
Adverse drug reactions (ADRs) are now recognized as an important cause of hospital admissions, with a proportion ranging from 0.9–7.9%. They also constitute a significant economic burden. We thus aimed at determining the prevalence and the economic burden of ADRs presenting to Medical Emergency Department (ED) of a tertiary referral center in India 相似文献25.
In many cases of interspecific kleptoparasitism, hosts developdefensive behaviors to minimize the impact of kleptoparasites.Because vigilance and defensive behaviors are often costly,selection should favor hosts that adjust the amount of investmentneeded to minimize losses to kleptoparasitism. However, examplesof such facultative responses are rare. Here, we investigatethe response of cooperatively breeding pied babblers (Turdoidesbicolor) to the drongo (Dicrurus adsimilis), an avian kleptoparasitethat regularly follows pied babbler groups, often giving alarmcalls to alert the group to predators but also occasionallygiving false alarm calls in order to steal food items. We showthat pied babbler response to drongos varies markedly accordingto babbler group size. In small groups, where there are fewindividuals available to act as sentinels, babblers sentinelless when a drongo is present and respond strongly to drongoalarm calls. However, in large groups, where there are manyindividuals available to participate in predator vigilance,babblers sentinel more often when a drongo is present, rarelyrespond to drongo alarm calls, and aggressively displace drongos,with a consequent decline in the number of successful kleptoparasitismevents. This behavior represent a facultative response to akleptoparasite according to the costs versus benefits of toleratingtheir presence. 相似文献
26.
Anbu Rajan L Joseph TC Thampuran N James R Ashok Kumar K Viswanathan C Bansal KC 《Biotechnology letters》2008,30(8):1403-1407
The genes involved in the biosynthetic pathway of ectoine (2-methyl-1,4,5,6-tetrahydropyrimidine-4-carboxylic acid) from Bacillus halodurans were cloned as an operon and expressed in E. coli. Analysis of the deduced ectoine biosynthesis cluster amino acid sequence revealed that the ectoine operon contain 2,389 bp, encoded by three genes; ectA, ectB and ectC that encode proteins of 189, 427 and 129 amino acids with deduced molecular masses of 21,048, 47,120 and 14,797 Da respectively. Extracts of induced cells showed two bands at 41 kDa and 17 kDa, possibly corresponding to the products of the later two genes. However the expression of ectA gene could not be ascertained by SDS-PAGE. The activity of the ectA protein was confirmed by an acylation assay. The transgenic E. coli accumulated upto 4.6 mg ectoine/l culture. This is the first report of an engineered E. coli strain carrying the ectoine genes of the alkaliphilic bacterium, B. halodurans. 相似文献
27.
Dolman KM Brouwer N Frakking FN Flatø B Tak PP Kuijpers TW Førre O Smerdel-Ramoya A 《Arthritis research & therapy》2008,10(2):R32
Background
Mannose-binding lectin (MBL) is an innate immune protein. The aim of our study was to determine whether genetically determined MBL deficiency is associated with susceptibility to juvenile rheumatoid arthritis (JRA) and whether MBL2 genotypes are associated with JRA severity. 相似文献28.
Lawson B Robinson RA Neimanis A Handeland K Isomursu M Agren EO Hamnes IS Tyler KM Chantrey J Hughes LA Pennycott TW Simpson VR John SK Peck KM Toms MP Bennett M Kirkwood JK Cunningham AA 《EcoHealth》2011,8(2):143-153
Finch trichomonosis emerged in Great Britain in 2005 and led to epidemic mortality and a significant population decline of greenfinches, Carduelis chloris and chaffinches, Fringilla coelebs, in the central and western counties of England and Wales in the autumn of 2006. In this article, we show continued epidemic spread of the disease with a pronounced shift in geographical distribution towards eastern England in 2007. This was followed by international spread to southern Fennoscandia where cases were confirmed at multiple sites in the summer of 2008. Sequence data of the ITS1/5.8S/ITS2 ribosomal region and part of the small subunit (SSU) rRNA gene showed no variation between the British and Fennoscandian parasite strains of Trichomonas gallinae. Epidemiological and historical ring return data support bird migration as a plausible mechanism for the observed pattern of disease spread, and suggest the chaffinch as the most likely primary vector. This finding is novel since, although intuitive, confirmed disease spread by migratory birds is very rare and, when it has been recognised, this has generally been for diseases caused by viral pathogens. We believe this to be the first documented case of the spread of a protozoal emerging infectious disease by migrating birds. 相似文献
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30.
D J Morris S A Latif T J Conca L T Wei C O Watlington D N Kirk H C Toms C H Shackleton 《Steroids》1990,55(11):482-487
Incubation of aldosterone with confluent layers of A6 (toad kidney) cells leads to its hydroxylation at the 6 beta-position. 6 beta-Hydroxyaldosterone is the major metabolite when the incubation is carried out at pH 6.8, whereas the product comprises 6 beta-hydroxy-17-isoaldosterone accompanied by some 6 beta-hydroxyapoaldosterone at pH 7.4. All products were identified by high-field 1H nuclear magnetic resonance spectroscopy. Control experiments indicated that the side-chain isomerization to form the 17-iso and apo derivatives occurs after the cytochrome P 450-dependent synthesis of 6 beta-hydroxyaldosterone. 相似文献