[Changes of chromatin structure state in thymocites at the early stage of apoptosis induced by hydrogen peroxide and radiation]. / Zminy strukturnoho stanu khromatynu v tymotsytakh na rann'omu etapi apoptozu za induktsiï peroksydom vodniu i radiatsiieiu.

The paper deals with changes in the structural state of chromatin in isolated thymocites at the early stage of apoptosis induced by hydrogen peroxide and radiation. Content of necrosis and apoptosis cells in the suspension of the isolated rat thymocites, during 3-hour incubation after X-ray irradiation in a dose of 4.5 Gy or with the presence of 0.1 microM of H2O2 by the method of double lifetime staining by fluorescent dye Hehst 33342 and propydium iodide has been estimated. Apoptogenic effect of the studied effects has been found out, the dynamics of condensation and internucleosomic chromatin fragmentation has been established. It has been shown that 100 microM alpha-tocopherol inhibited completely DNA fragmentation in the cells incubated with H2O2 and only partially in irradiated cells. Introduction of postmitochondrial supernatant, isolated from the incubated control or irradiated cells, into the cell-free system which included the ATP-regenerating system and nuclei of control thymocites did not affect the level of DNA fragmentation, while the increase of the level of fragmented DNA in nuclei was observed in the presence of the supernatant obtained by centrifugation of the cells treated by H2O2. Differences of mechanisms of thymocite apoptosis initiation, as affected by hydrogen peroxide and ionizing radiation, is discussed.

[Bile secretion and the nuclear transcriptional activity of rat liver cells under the action of bile acids]. / Sekretsiia zhovchi ta transkryptsiina aktyvnist' iader klityn pechinky shchuriv pry diï zhovchnykh kyslot.

The intensity of rat's bile secretion under the intraportal infusion of cholic and taurocholic acids has been studied. The results demonstrate that bile acids decrease bile secretion rate under the infusion of these acids in the physiological saline, and increase bile secretion rate under the infusion in saline, with hydrocarbonic ions. Previous treatment by the transcriptional inhibitor actynomycin D affected the development of the hypercholeretic action of the taurocholic acid. The transcriptional activity of the isolated nuclei of liver cells is increased under taurocholic acid action, and decreased under the cholic acid action. The results show that choleretic effects of the bile acids is realised, at least, partially, on the level of the regulatory molecular mechanisms of the cell, the transcription among them.