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AV Krylov YN Antonenko EA Kotova TI Rokitskaya AA Yaroslavov 《Canadian Metallurgical Quarterly》1998,440(1-2):235-238
Effect of a cationic polymer, poly(L-lysine), on the kinetic properties of ionic channels formed by neutral gramicidin A (gA) and its negatively charged analogue O-pyromellitylgramicidin (OPg) in a bilayer lipid membrane is studied using a method of sensitized photoinactivation. This newly developed method is based on the analysis of transmembrane current transients induced by a flash in the presence of a photosensitizer. It has been shown previously that the time course of the flash-induced current decrease in most cases follows a single exponential decay with an exponential factor (tau, the characteristic time of photoinactivation) that correlates well with the single-channel lifetime. Addition of polylysine does not affect tau for gA channels, but causes a substantial increase in tau for OPg channels. This effect is reversed by addition of polyacrylic acid. The deceleration of the photoinactivation kinetics is ascribed to electrostatic interaction of polylysine with OPg probably resulting in OPg clustering. The latter can stabilize the channel state by reducing the rotational and lateral mobility of OPg monomers and dimers, and thus increase the single channel lifetime. 相似文献
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Müller cells constitute the principal glia of the vertebrate retina. Unlike other types of neuroglial cells such as astrocytes and Schwann cells, Müller cells have not yet been demonstrated to express Na+ channels. Here we present first evidence of Müller cell Na+ currents from voltage-clamp studies in enzymatically isolated cells. Some cells from retinae of cats and dogs, but none from rabbit or guinea-pig retinae, revealed fast and rapidly inactivating inward currents in response to depolarizing voltage steps. The currents reversibly disappeared in Na+ free solutions or under tetrodotoxin (TTX, 1 microM). Activation and inactivation characteristics of these currents were strikingly similar to those of neurone-type Na+ channels. 相似文献
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TI Berge 《Canadian Metallurgical Quarterly》1997,55(1):64-69
This series presents six cases of a rare variant of dermatofibroma, characterized by marked clear cell change. All lesions occurred on the lower extremities of middle-aged adults (four women, two men), mostly with the clinical diagnosis of fibrohistiocytic lesion. Histological examination revealed well circumscribed, faintly stained dermal to subcutaneous lesions which were due to the overwhelming presence of clear cells (> 90%), some with prominent PAS-positive cytoplasmic granulation. Overlying epidermal hyperplasia as well as storiform arrangement of spindle cells, sclerotic collagen and some interspersed lympho-histiocytic infiltrate at the periphery of the lesion indicated the fibrohistiocytic origin. Individual histopathological peculiarities included: bizarre giant cells in two cases, perifollicular arrangement and haemangiopericytoma-like features with iron deposition in one case each. Immunohistochemically three of four lesions showed moderate reactivity for factor XIIIa and two of four with an anti-metallothionen marker E9, but were otherwise negative with a broad panel of markers. Electronmicroscopy in two cases revealed large pools of glycogen beside focal, prominent endoplasmic reticulum and lysosomes in some granular cells, but only optically translucent cells in cases of clear cells. Recognition of clear cell dermatofibroma is important as the differential diagnosis includes some entities with more serious outcome/considerations such as metastases of renal cell carcinoma, xanthogranulomatous reactions, balloon cell naevus/melanoma and clear cell sarcoma. 相似文献
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B. V. Kuz'min B. V. Savinov L. S. Gerasimova Yu. A. Tolkachev É. M. Aizenshtein K. N. Ushakova 《Fibre Chemistry》1985,16(6):427-429
Conclusions The use of a technological scheme which combines the processes of twisting and yarn heat-treatment makes it possible to intensify the process of textile grade polyester yarn manufacture as a result of shortening the series of textile-technology steps.The scheme permits one not only to set the twist well, but also to regulate the basic physicomechanical properties of the yarns over a wide range.By using the proposed technological scheme, depending on the assigned degree of deformation, one can obtained twisted yarns with a shrinkage of 1–2% at an initial elastic modulus up to 20 MPa.Translated from Khimicheskie Volokna, No. 6, pp. 32–33, November–December, 1984. 相似文献
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