[Research on Chinese drug compounds. I].
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Chemistry, Pharmaceutical↗
Biomedical subjects
H H Yin
Publications and source records attributed to H H Yin.
The relation of endogenous adenosine cyclic 3':5'-monophosphate to the antagonistic effects of adenosine and colchicine on cell shape.
Adenosine and colchicine have antagonistic effects on cell shape. When Chinese Hamster lung fibroblasts (CHE36-6) or SV40 transformed 3T3 (SV3T3) cells are incubated with colchicine (1 muM) for one hour at 37 degrees C, they round up into spheres with short spikes. Cells treated with adenosine (1 muM-minus 4 mM) for one hour become refractile and develop spindly processes. However, when the two compounds are added simultaneously, the characteristic responses to either drug are abolished and the cells appear normal. The counteraction is specific for adenine and its derivatives, adenosine being the most effective of the compounds we tested. Accumulation of colchicine or adenosine is not altered significantly by the presence of the other drug, ruling out decreases in uptake as the basis of the mutual antagonism. The morphological changes can be observed under conditions where there are no changes in intracellular cAMP levels (such as incubation with low concentrations of adenosine or cordycepin, an adenosine analog that cannot be directly converted to cAMP). Colchicine does not alter cAMP content of control or adenosine-treated cells. These data show that adenine compounds have potent effects on cell shape, and the antagonistic effects of adenosine and colchicine on cell shape are not mediated through changes in intracellular cAMP levels.
Adenine↗
Control of cell surface topography.
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Binding Sites↗
A comparative evaluation of the distribution of concanavalin A-binding sites on the surfaces of normal, virally-transformed, and protease-treated fibroblasts.
The topographical distributions of concanavalin A-binding sites on the surfaces of 3T3, proteasetreated 3T3, and simian virus 40-transformed 3T3 cultured mouse fibroblasts appear to be different, as shown by a shadow-cast replica technique using concanavalin A and a hemocyanin marker, or as shown previously on isolated membranes with concanavalin A coupled to ferritin. However, chemical fixation of cells before labeling with concanavalin A and hemocyanin, or labeling exclusively at 4 degrees , allows one to distinguish between inherent concanavalin A-binding-site topography and potential rearrangement of sites induced by the action of the multivalent concanavalin A molecule itself. The inherent distribution of binding sites on 3T3, protease-treated 3T3, and transformed cells is actually the same on all cells, i.e., dispersed and random. Treatment of unfixed transformed or protease-treated 3T3 cells, but not normal 3T3 cells, with concanavalin A and hemocyanin at 37 degrees (or at 4 degrees with subsequent warming to 37 degrees ), however, results in clustering of binding sites, presumably due to crosslinking of neighboring lectin-binding sites by the quadrivalent concanavalin A. Thus, the underlying difference between concanavalin A-binding sites on normal as compared with transformed or protease-treated normal cells lies not in the inherent topography of binding sites, but rather in the susceptibility of the sites to aggregation by concanavalin A. The latter may reflect an increased mobility of lectin-binding sites on transformed or protease-treated cells.
Animals↗
Effect of colchicine, colcemid, and vinblastine on the agglutination, by concanavalin A, of transformed cells.
The sensitivity of transformed 3T3 fibroblasts to agglutination by concanavalin A is reduced by alkaloids that bind specifically to protein subunits of microtubules.
Agglutination↗