[Mechanism of action of pafencil on sensitive and resistant tumor cells].
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Biomedical subjects
Publications and source records attributed to L E Ivanova.
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A comparative quantitative investigation of colony-forming ability of mouse bone marrow hemopoietic stem cells in the case of ordinary leukemia variant (P-388) and carminomycin-resistant variant (P-388/k) was carried out. Leukemia bearing mice received single injections of increasing doses of carminomycin on the 5th day after transplantation and 24 hours later the bone marrow was investigated for quantity of colony-forming units in the spleen (CFUs). Dynamics investigation of bone marrow cells in the case of P-388 and P-388/k (without treatment) reveals the common tendency to a decrease of these cells in the period before animal death. Sensitivity of colony forming cells (CFUs) to different doses of the antibiotic of mouse bone marrow in both cases (P-388 and P-388/k) was practically the same. Dynamics of CFUs in two populations of cells after a single injection of carminomycin in doses causing the killing of 50% of CFUs showed that the antibiotic inhibited CFUs equally (50%). However this inhibition in case of CFUs with P-388/k leukemia was almost five times longer than in the case of ordinary P-388 one. Based on the investigations conducted the second injection of the antibiotic to mice with P-388/k leukemia on the fifteenth day after the first one may be recommended.
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Considerable decrease of polysome number (22% as compared with 48% in normally grown culture) was observed under methionine starvation of E. coli Hfr (Met-)culture . At the same time the amount of 70S ribosomes increased up to 32%, while it was 2--6% in the control, the content of free ribosome subunits (50S+30S) being stable. The number of polysomes was the same (congruent to 50%) both in the control culture and under inhibition of protein synthesis in E. coli Hfr(Met-) cells with chloramphenicol, the content of 70S ribosomes was increased (30%) like in the case of methionine starvation, and the amount of free ribosome subunits was decreased (24% as compared with 46% in the control). The rate of ribosome movement in polysomes in the presence of chloramphenicol is comparable with that in the control. The rate of ribosome movement along mRNA under methionine starvation in 1.6 times lower than in normally grown E.coli culture. The level of (14)C-leucine incorporation into newly synthesizing polysome proteins under chloramphenicol inhibition of protein synthesis and methionine starvation comprised 20% and 12% of the incorporation level inthe control respectively. It suggested that ribosomes under inhibition of protein synthesis by chloramphenicol or amino acid starvation continue their movement along mRNA with the rate comparable with that in the control. However in this case no peptide bonds are formed ("abortive" translocation).