[The effect of staphylococcal alpha-toxin on DNA replication in human cells]. / Vliianie stafilokokkovogo al'fa-toksina na replikatsiiu DNK v kletkakh cheloveka.

The influence of Staphylococcus alpha-toxin has been investigated on the duration of S-phase of lymphocyte mitotic cycle and on DNA replication in human fibroblasts in vitro. The duration of the S-phase of lymphocytes was measured by counting labeled metaphases and by making replication curves. Alpha-toxin in a dose of 3 micrograms/ml enhances the onset of S-phase, which is inhibited at a dose of 33 micrograms/ml of alpha-toxin. The action of alpha-toxin resulted in a decreased rate of replication fork and in a progressive activation of replicon groups. This effect was most prominent at 33 micrograms/ml of alpha-toxin. The data obtained allow to suggest that immunodeficiency of the second order, so characteristic of the staphylococcal sepsis, may be due, in many respects, to suppression of DNA replication.

[Changes in the cytogenetic indices in the bone marrow cells of white rats undergoing mechanical trauma of various degrees of severity]. / Ob izmeneniiakh nekotorykh tsitogeneticheskikh pokazatelei v kletkakh kostnogo mozga belykh krys pri mekhanicheskoi travme razlichnoi tiazhesti.

The influence of traumatic shock on some cytogenetic indices in bone marrow cells was investigated in white mongrel rats. The traumatic shock was caused by the Noble-Collip method. Comparative analyses of cytogenetic indices during trauma of different intensity show that the most acute changes involve the percentage of aberrant metaphases, and of average number of chromosome breaks per cell. Dynamics of changes of cytogenetic indices after a heavy trauma show that the traumatic shock may exert a cytogenetic effect maintaining for 18 hours. The results obtained and the analysis of literary data enables us to suggest that the speed of development of changes, and restoration of cytogenetic indices under various forms of trauma is quite different and may serve another confirmation of the hypothesis above the possibility of increasing the process of mutagenesis at the expense of the violation of homeostasis.

[Number of chromosome aberrations induced by chemical carcinogens in the cells of patients with 2 forms of xeroderma pigmentosum]. / Chastota aberratsii khromosom, vyzyvaemykh khimicheskimi kantserogenami v kletkakh dvumia formami pigmentonoi kserodermy.

A study was made of the effects of a chemical mutagen of the "gamma-type"--methylmethansulfonate (MMS) and of mutagen of the "UV-type"--4-nitroquinolin-1-oxide (NQO) and 7-brommethylbenz(alpha)antracen (BMBA) exerted on chromosome aberration frequency in lymphocytes of patients with classical Xeroderma pigmentosum and with a so-called form II of the disease on different stages of the cell cycle. Mutagens were added to PHA stimulated lymphocyte cultures every 3 hours, simultaneously with pulse 3H-thymidine labelling, to fix the stage of the cell cycle at the moment of treatment. NQO and BMBA treatments were found to increase the frequency of chromosome aberrations in classical XP cells, whereas MMS was not found to. In the XP II cells, defective in repair of both UV and gamma damaged DNA, chromosome aberrations yield is higher than in normal cells after all the three mutagens treatment. The data obtained show the correlation between DNA repair and chromosome aberrations yield.