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211.
C G Francisco R Freire R Hernandez J A Salazar E Suarez G A García de la Mora J A Noguez A Acosta O Jimeno 《Steroids》1983,41(3):267-275
The synthesis of nine new esters of norethisterone (17 alpha-ethynyl-17 beta-hydroxyestr-4-en-3-one) is described, with the esterifying acids bearing an acetylenic or olefinic function in a chain of eight or nine carbon atoms, for evaluation as long-acting contraceptive agents. 相似文献
212.
Christine Jolicoeur Josette Noël Léa Brakier-Gingras 《Biochemical and biophysical research communications》1983,115(1):153-158
Polysomes from the skeletal muscle of normal and dystrophic hamsters were dissociated into ribosomal subunits by treatment with puromycin and the subunits from both strains were reassociated in all possible combinations. When their protein synthesis activity was assayed in a poly(U)-directed cell-free system at a low magnesium concentration, the reassociated ribosomes from dystrophic hamsters were less active than the ribosomes from control animals. The ribosomal defect is a property of the 60S subunit and is due to a ribosomal component rather than to abnormal binding of a non-ribosomal protein. 相似文献
213.
We have calculated translational and rotational diffusion coefficients and intrinsic viscosities of oligomeric structures composed of n identical subunits having a prolate ellipsoidal shape with axial ratio p. Results are presented for p = 1-6 for a variety of structures with n = 1-6. We compare our results with those obtained by a different modeling procedure, proposed by other workers, in which the monomeric subunit is represented as a string of touching, colinear spheres. If n and an estimate of p are known, the structure of the oligomer can be. in most cases, unambiguously determined by comparison of the experimental oligomer-to-monomer ratios of a given property with the numerical results of this work. As examples of the applicability of our results, we examine the relationship between structure and properties for neurophysin. bovine serum albumin, hemoglobin and phycocyanin. 相似文献
214.
The pancreatic -cell recognition of insulin secretagogues. II. Site of action of tolbutamide 总被引:2,自引:0,他引:2
Bo HellmanJanove Sehlin Inge-Bert Täljedal 《Biochemical and biophysical research communications》1971,45(6):1384-1388
The distribution of 35S-labelled tolbutamide was studied in microdissected pancreatic islets of obese-hyperglycemic mice. These islets contain more than 90 % β-cells. A comparison with the uptake of 3H-labelled sucrose, mannitol, or 3-O-methyl-D-glucose revealed that tolbutamide did not enter the β-cells but was restricted to the extracellular space. It is suggested that the β-cell plasma membrane contains a tolbutamide receptor, which is responsible for the recognition of sulfonylureas as insulin secretagogues. 相似文献
215.
Karl-Anders Karlsson Bo E. Samuelsson Göran O. Steen 《The Journal of membrane biology》1971,5(2):169-184
Summary Ducks (Anas platyrhynchos) were fed hypertonic saline for eight days, resulting in an activation and hypertrophy of the salt gland. The Na+–K+-dependent adenosine triphosphatase, an enzyme generally assumed to be part of the active Na transport system, increased its specific activity by about 200% during this activation. Sulfatides, the major glycolipids of the salt gland, increased their concentration to the same extent. Cholesterol, cerebrosides, and six phospholipid classes showed an increase of 20–80%.A preliminary report on this work was given at the Second International Meeting of the International Society for Neurochemistry, Milan, September 1–5, 1969, and at the XIIIth International Conference on the Biochemistry of Lipids, Athens, September 7–12, 1969. 相似文献
216.
217.
218.
The antibiotic activity of the antifungal substance mucidin was compared with the activity of nystatin and pimaricin. The antibiotics were tested by the plate method using 19 fungal species, mainly phytopathogenic ones. Toward 14 species, mucidin was ten times more active than nystatin and pimaricin, toward 5 species the activities were roughly the same. The antibiotics differed also in the sharpness of the inhibition zone boundaries. 相似文献
219.
220.
Thorotrast uptake and transit in embryonic glia, heart fibroblasts and neurons in vitro 总被引:6,自引:0,他引:6
Norman K. Wessells Marilyn A. Luduea Paul C. Letourneau Joan T. Wrenn Brian S. Spooner 《Tissue & cell》1974,6(4):757-776
Thorotrast (colloidal ThO2) is incorporated into coated vesicles, various agranular vesicles and sacs, and a surface-associated system of membranous channels in times as short as 1 min by single cultured glial and heart cells. Thorotrast appears in ‘C’-shaped bodies and in small, dense bodies of the lysosomal series within ca. 25 min. With longer chase periods, thorotrast ‘clears’ from all cytoplasmic organelles except the lysosomal series. The technique of applying thorotrast and using varying chase periods fails to distinguish a class of membranous organelles, located close to the cell periphery, that might serve as a source of new cell surface during locomotory activity. Similarly, thorotrast (colloidal ThO2) is incorporated into almost all classes of membrane-bounded organelles of growth cones and axons of single nerve cells in vitro in times as short as 1 min. This includes elements of the smooth endoplasmic reticulum. No thorotrast enters the lysosomal granules in this short time. During various chase periods, the tracer disappears from the initial sites of incorporation and accumulates in dense bodies of the lysosome series within growth cones and axons. ‘C’-shaped bodies may be an intermediate in that process. No unique sites of endocytotic activity or of a complete absence of endocytosis were observed that could be correlated with growth cone function and axonal elongation, though the presence of the tracer in agranular sacs of the smooth endoplasmic reticulum in growth cones could reflect hypothesized cycling of cell surface (Bray, 1973). 相似文献