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831.
Deposition of fibronectin on material surfaces exposed to plasma: quantitative and biological studies 总被引:2,自引:0,他引:2
Experiments were carried out to characterize plasma fibronectin deposition onto material surfaces exposed to plasma solutions. Under nonclotting conditions, the amount of fibronectin adsorption on the surfaces, determined by an indirect radioactive antibody assay, was maximal at low plasma concentrations (0.1%). At higher concentrations of plasma, other plasma proteins appeared to compete with and inhibit adsorption of fibronectin. Biological activity (fibronectin-promoted cell spreading) was also greatest at low plasma concentrations and decreased as the plasma concentration was raised. When surfaces were exposed to plasma under clotting conditions (i.e., addition of Ca2+ and thrombin), fibronectin deposition on the surfaces and biological activity remained constant or increased as the plasma concentration was raised. Based on indirect immunofluorescent antibody assays, the fibronectin deposited from clotting plasma appeared to be in a punctate distribution over the entire material surface and occasionally was associated with discrete fibrillar structures. The increased deposition of fibronectin from clotting plasma compared to nonclotting plasma (approximately a 10-fold difference with 10% plasma) was partially a result of covalent crosslinking of fibronectin to fibrin based upon studies with putrescine added to inhibit crosslinking during clotting. On the other hand, the increase in biological activity that occurred if the surfaces were exposed to clotting plasma was completely inhibited by putrescine, indicating that fibronectin had to be crosslinked to fibrin to have biological activity under these conditions. Finally, fibronectin deposition also occurred on surfaces exposed to whole blood and was markedly enhanced when clotting occurred. 相似文献
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834.
Vicente Gomes Maria José A. C. R. Passos Neusa M. P. Leme Thaís C. A. Santos Débora Y. F. Campos Fabio M. Hasue Van Ngan Phan 《Polar Biology》2009,32(7):1009-1021
The photo-induced toxicity of anthracene was investigated as the mortality in Antarctic shallow water amphipod, Gondogeneia antarctica, at different concentrations of anthracene and different periods of exposure to natural sunlight and artificial UVA and UVB
radiations. When exposed to natural sunlight, animals contaminated in the dark and placed in clean water or in anthracene
solutions showed different degrees of mortality, dose–time dependent. Effects were even more evident when these animals were
exposed to artificial UVA or UVB radiations. Depuration seemed to be a slow process. The effects of UV radiation and anthracene
alone and the effects of the interactions of these two stressors implied that solar radiation is an important parameter that
deserves consideration in the environmental assessment of polycyclic aromatic hydrocarbons in Antarctic coastal waters. G. antarctica proved to be a good bioindicator for the phototoxicity of anthracene in Antarctic shallow waters. 相似文献
835.
Cu(II)-Poly-(1-ornithine) complexes in aqueous solution have been studied using potentiometric titration and absorption and circular dichroism spectra. As in the case of Cu(II)-poly(L-arginine) complexes studied previously, two types of compounds have been detected, labeled complexes I and II. Complex I contains two amine nitrogens and two water molecules coordinated to the copper. Complex II, two amine and two amide nitrogens. Amide nitrogen coordination confers optical activity to the copper d-d transitions. Furthermore, amine and amide nitrogen coordination to the copper are characterized by charge transfer transitions at 250 and 320 nm respectively which were already identified in Cu(II)-poly(L-arginine) systems. 相似文献