Biomedical subjects
Publications and source records attributed to A V Timoshenko.
It has been shown that hyperthermia (45 degrees C, 20-120 min) produces a number of changes in HeLa cells at the plasma membrane level: shedding of membrane glycoproteins; changes in the lectin-induced cell agglutination; the outflux from cells of substances with the nonspecific esterase activity.
Changes of hydrogen ions activity in rat thymocytes were studied during the process of concanavalin A (Con A) endocytosis by cells. A possibility was shown to use fluoresceinisothiocyanate-labeled Con A for measuring pH values in the sites of mitogen localization. It is established that during the action of Con A endocytotic vesicles with low pH value are formed, while the pH value of the cytoplasm is increased. The pH value measured in the sites of mitogen localization depends on the treatment of cells by alpha-methyl-D-mannoside and sodium azide. Mechanisms of acidic-basic equilibrium changes in the cytoplasm of lymphocytes upon cell stimulation with mitogens are discussed.
Data from literature concerning cell aggregation induced by various substances are considered. The biochemical nature of cell aggregation inducers, participation of membrane receptors in this process, biochemical aspects and practical significance of the cell aggregation process are discussed.
It has been shown that of active oxygen species regulate the activity of the processes of Con A endocytosis in rat thymus cells.
Fluorescein mercury acetate (FMA), a fluorescent probe, is used for the investigation of SH-groups of thymocytes' plasma membrane. It is found that mitogenic lectin Con A decreases the amount of membrane SH-groups and increases the fluorescence polarization degree of FMA (PFMA). The value of PFMA increases also during the incubation of cells with potassium ferricyanide and H2O2 but it decreases in the presence of NADH. The analysis of the data permits a conclusion that the thymocyte activation by Con A results in the selective oxidation of certain SH-groups with the formation of disulphide cross-linking between the plasma membrane receptors bound with the lectin molecules.