Izvestiia Akademii nauk SSSR. Seriia biologicheskaia最新文献

Effects of alkylating antitumor drugs on resting (G0 phase of cell cycle) and proliferating (G1, S, G2 and M phases) hepatocytes were studied in regenerating mouse liver. Cell cycle kinetics (fraction of labeled mitoses, labeling and mitotic indices) were determined by 3H-thymidine autoradiography. Dipin and fotrin as a DNA-damaging agents attack mainly resting (G0) and proliferating (G1) cells. Effect of the damage results in the inhibition of DNA synthesis and G2 phase arrest in the following mitotic cycle. An alkylating drug phopurin as well as ara-C both suppress the mitotic progression in proliferating hepatocytes and do not influence the resting cells.

Based on informational approach to the comparative analysis of DNA sequences and the conception of fuzzy relations, new classification schemes were suggested for two aggregates of tRNA genes from the EMBL-8 data bank connecting amino acids TRP and ASP. These classification schemes are presented as a dendrogram and reflect possible evolutionary interrelation between tRNA genes in both aggregates. Evolutionary interrelations between tRNA genes were analyzed from two standpoints: 1) taking into consideration the interrelation between DNA sequences by all four nucleotides; 2) taking into account possible evolutionary pressure to the divergence of DNA sequences towards transitions. The similarity and difference of dendrograms for each gene aggregate were considered in both instances. It was shown that the analysis of all possible directions of the evolutionary pressure to the divergence of DNA and RNA sequences provides a new approach to the construction of a global tRNA phylogeny.

Effect of fluorouracil in combination with ascorbate and L-valin, modifiers of lipid metabolism was studied in cultured protozoa Crithidia oncopelti. The inhibitory effect of preparation in a concentration of 100 mcg/ml gradually decreased in the course of cultivation. Its readdition to a 96-hour culture did not increase its effect on protozoa cells. Combined addition of fluorouracil and modifiers (100 mcg/ml each) resulted in insignificant decrease of the cell accumulation in the culture as compared with the effect of fluorouracil alone. When fluorouracil and modifiers were readded to the 96-hour culture, the trypanostatic effect of preparation was 2.5 times enhanced. This enhancement was confirmed by destructive alterations in cell morphology and by the culture lysis by 192 h of protozoa cultivation.

It was shown that the mechanism regulating the oxyhemoglobin coagulation in presence of a mercury reagent in large amount differs from that in presence of the reagent in relatively small concentrations. The significance of a large class of ligands at mercury atom during the oxyhemoglobin coagulation was demonstrated. Several theoretical generalizations are drawn.

The disturbance in energetic metabolism of Ehrlich ascite carcinoma cells during antitumor drug treatment was examined using high-resolution 31P-NMR. The value of antitumor drug effect was shown to be characterized by the kinetics of ATP and KF level alteration in tumor cells. The results correlated with the indexes of therapeutical activity of studied drugs.

No decrease in iron-sulphur centers was found in cultured macrophage cells (J774) after the treatment with nitric oxide (10(-7) M NO/10(7) cells) during 5 min. The center content was controlled by the electron spin resonance (ESR) method. The macrophages pretreated with dithionite + methyl viologen showed the formation of dinitrosyl iron complexes (DNIC) with a characteristic ESR signal at g approximately 2.03. The data suggest that loosely bound nonheme iron (free iron) mostly contributes to the formation of these complexes. Iron from iron-containing proteins does not release from these centers under the direct action of nitric oxide. The iron-sulphur centers can be destroyed by the products of nitric oxide oxidation (NO2, N2O3, etc.) as oxidizing and acid agents.

Principal problems of glucocorticoid hormone application in non-endocrine diseases are discussed proceeding from the mechanism of their action and the role in organism's life. It appeared that the hazard of glucocorticoid therapy is mainly due to the absence of a test for sufficiency and real needs in these hormones. It was shown that the test has to be introduced reflecting on the whole body level the glucocorticoid activity in the cell, that is similar to blood glucose in relation to insulin. The introduction of free blood tyrosine as such test appears to allow the development of safe individual strategy for the usage of glucocorticoids.

Hepatocytes and the fraction of non parenchymal cells enriched with oval cells were extracted from the preneoplastic mouse liver at the stage of hyperplastic node formation and implanted into the spleen. In 14-16 months after the transplantation, multiple islets of hepatocytes which replaced up to 25% of the spleen cut area, were found in 57% (4 of 7) and 22% (8 of 36) of recipients respectively. The hepatocytes formed 2-3-cell bulks or solid masses organized into multicellular trabecules, and expressed biliary capillary antigen, albumin and transferrin. In the inoculation of nonparenchymal cell fraction, the growth of hepatic tissue in the spleen depended on the magnitude of hepatocyte admixture to be undetectable in absence of hepatocytes in the donor suspension. The growth of hepatic tissue in spleen was observed following the injection of a small number (3 x 10(-4)-6 x 10(-5)) of live hepatocytes. This fact evidences an extremely high clonogenic potency of clonogenic potency of preneoplastic hepatocytes.

Effect of retinoic acid (RA) on morphogenesis and proliferation of regenerating extremity and lens cells was studied using 3H-thymidine autoradiography and morphometry. The 3H-thymidine incorporation into the inner layer of dorsal and ventral iris was 1.5-3 times reduced by the 8th day following the RA administration. The applied RA dose (0.25 mg per animal) exerted no significant effect on the morphogenesis of regenerating lens with the exception of the case of forming an additional lens from dorsal iris. The RA effect on the regeneration of extremity corresponds to available data of literature and manifests itself in the decelerated regeneration and the appearance of additional structures along the proximodistal axis.

Autofluctuations in the numbers of bacteria, leukocytes and epithelial cells were observed in the vaginal secretion of Syrian female hamsters. The amplitude of fluctuations depended both on individual features of females and on environmental factors like light conditions. It was suggested that vaginal bacteria perform functions of a stimulator for local immunity to protect against infections and play a sanitary role to eliminate epithelial cells and remains of spermatozoids. A case is possible that products of the bacterium vital activity contribute also to the formation of female sex pheromone.