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N A Setkov

Publications and source records attributed to N A Setkov.

30 records · Page 2Linked to original sources
PubMed1989

[DNA synthesis in the nuclei of stimulated NIH 3T3 cells in heterodikaryons obtained by the fusion of these cells with resting cells treated with cycloheximide].

Serum-deprived (0.2%) resting NIH 3T3 mouse fibroblasts preincubated with cycloheximide (7.5 micrograms/ml) were fused with stimulated cells taken 10 hours after changing the medium to the one containing 10% serum, and DNA synthesis was investigated in nuclei of heterodikaryons, homodikaryons, and monokaryons, using radioautography with double-labeling technique. Preincubation of resting cells with the inhibitor of protein synthesis cycloheximide for 4, 3, 2, but not for 1 or 0.5 hours abolishes their ability to suppress DNA synthesis in stimulated nuclei in heterodikaryons. Three hours after the removal of cycloheximide from the media, the resting cells acquire once again the inhibitory effect towards the entry of stimulated nuclei into the S-period. The data suggest that the resting cells may produce a labile endogenous inhibitor of cell proliferation, and support the idea on the active metabolic processes occurring in the resting cells.

Animals↗
PubMed1989

[Determination of serum and plasma erythropoietin in mice with phenylhydrazine-induced anemia].

The simple, specific and sensitive erythropoietin bioassay in serum and plasma from phenylhydrazine treated mice is described, based on H3-thymidine incorporation into divided hemopoietic cells. Spleen cells taken from mice on the third day following the second of 2 daily injections of phenylhydrazine were cultured in 24 hours in the presence of test material. Following incubation for 2 hours with H3-thymidine solution radioactivity was measured.

Anemia↗
PubMed1984

[Dependence of the entry of NIH 3T3 cells into a period of DNA synthesis on the duration of their preliminary resting state].

Using radioautography and cell fusion technique, we studied cell kinetics and functional properties of NIH 3T3 mouse fibroblasts stimulated to proliferate after being quiescent for 3, 7 and 14 days. The resting state was achieved by cultivating cells in the medium with 0.5% of serum, the stimulation being achieved by replacement of the depleted medium for a fresh one containing 10% of serum. It was found that the longer cells had been kept resting, the longer their prereplicative period lasted after the stimulation, the lesser was the fraction of cells that entered the S-period. Cell-fusion experiments revealed that the ability of the resting nuclei to suppress the onset of DNA synthesis in the nuclei of stimulated cells in heterodikaryons increased as the cells stayed in the resting state before fusion, and that the period of suppression was prolonged. The data are consistent with the idea of cells going into deeper resting states. It may be concluded that the resting cells undergo a gradual development resulting in the changes of their functional properties.

Animals↗
PubMed1984

[DNA synthesis in the nuclei of resting and proliferating cells of the NIH 3T3 line in monokaryons, homo- and heterodikaryons].

Serum-deprived (0.5%) resting NIH 3T3 mouse fibroblasts were fused with stimulated cells taken at 2 hour intervals after changing the medium to the one containing 10% serum, and DNA synthesis was investigated in monokaryons, homodikaryons, and heterodikaryous using radioautography with double-labeling technique. The presence of the resting nucleus in the common cytoplasm has an inhibitory effect on the entry of the stimulated nucleus into the S period in the medium containing either 0.5 or 10% serum, but DNA synthesis continues. After a 24 hour stay in the common cytoplasm with resting nuclei the stimulated nuclei return into the state of rest. When resting cells are stimulated by 10% serum, their inhibitory effect on stimulated nuclei in heterodikaryons still persists for at least 2 hours following stimulation. Preincubation of resting cells with cycloheximide for 4 hours abolishes their ability to suppress DNA synthesis in stimulated nuclei. The data suggest that the resting cells produce an endogenous inhibitor of cell proliferation whose formation depends upon the synthesis of protein(s). When stimulated, cell can proliferate only upon decreasing the level of this inhibitor. The obtained results are consistent with the idea of a negative control of cell proliferation.

Animals↗
PubMed1983

Onset of DNA replication in nuclei of proliferating and resting NIH 3T3 fibroblasts following fusion.

NIH 3T3 mouse fibroblasts arrested in medium containing 0.5% serum were fused with stimulated cells taken at 2-h intervals after replacing the medium with one containing 10% serum, and DNA synthesis was studied in mono-, homo- and heterokaryons using radioautography with double-labelling technique. The presence of a resting nucleus in a common cytoplasm with a stimulated nucleus from the prereplicative period has an inhibitory effect on the entry of the stimulated nucleus into the S period in medium containing either 0.5 or 10% serum, but ongoing DNA synthesis continues. After a 24-h stay in a common cytoplasm with resting nuclei the stimulated nuclei return into the state of rest. When resting cells are stimulated by 10% serum, their inhibitory effect on stimulated nuclei in heterokaryons still persists, at least for 2 h following stimulation. Preincubation of resting cells with cycloheximide for 4 h abolishes their ability to suppress DNA synthesis in stimulated nuclei. The data suggest that resting cells produce an endogenous inhibitor of cell proliferation, whose formation depends upon the synthesis of protein. When stimulated, the cells can proliferate only after decreasing the level of this inhibitor. The results obtained are consistent with the idea of a negative control of cell proliferation.

Animals↗
PubMedDate not supplied

[Inhibitors of protein biosynthesis can stimulate proliferation of mouse hepatocytes in vitro].

Hepatocyte proliferation in the liver regenerating after partial hepatectomy ceases when the organ is restored, and the mechanism of this phenomenon is still unclear. In the experiments on fusing hepatocytes from the regenerated mouse liver (15 days after partial hepatectomy) with NIH 3T3 mouse fibroblasts, we revealed no DNA synthesis in the nuclei of stimulated fibroblasts in heterokaryons (in the presence of hepatocyte nuclei), whereas DNA synthesis in nonfused cells was undisturbed. In this work, our purpose was to find out whether the suppression of DNA synthesis in heterokaryons could be due to the appearance in hepatocytes of some endogenous factors having an inhibitory effect on proliferation. To this end, hepatocytes from the mouse liver regenerated after partial hepatectomy were treated with cycloheximide for 1-4 h and were then fused with stimulated fibroblasts. Such a short-term treatment of hepatocytes with cycloheximide proved to result in the loss of their ability to inhibit DNA synthesis in the nuclei of stimulated or quiescent fibroblasts in heterokaryons, but hepatocytes proper actively proliferated in the medium with a low serum content (0.2%). When the mice with the liver regenerated after partial hepatectomy were treated with a single sublethal dose of cycloheximide (3 mg/kg), their hepatocytes taken two days after this treatment had no inhibitory effect. Puromycin, another inhibitor o protein synthesis, had the same effect on hepatocytes. These results may be interpreted as evidence that the final stage of liver regeneration after damage is controlled by the factors having a negative effect on cell proliferation.

3T3 Cells↗