Aim: to study the effect incubation in NaCI hypertonic solutions on the yield of DNA single-strand breaks (SSB) and alkali-labile sites (ALS) induced by y-radiation and hydrogen peroxide in human peripheral blood lymphocytes in vitro. Material and methods. The lymphocytes isolated from the peripheral blood of healthy women donors aged 21-26 years were used for the study. Cell irradiation at doses of 1, 2, 3 and 5 Gy was performed using the "AGAT P1" unit (Russia, y-radiation source — 60Co, a dose rate of 1 Gy/min) at 4°C. In case of hydrogen peroxide exposure (25, 50 and 100 uM) the cells were incubated for 15 minutes at 4°C. Analysis of the DNA SSB and ALS was performed using the alkaline DNA comet assay. Results. Incubation of cells in 0.35 M NaCI solution (non-histone proteins dissociation) increases the yield of DNA SSB and ALS induced by v-radiation and hydrogen peroxide at ~ 1.3 times. Increasing the NaCI concentration to 0.6 M (linker histone H1 dissociation) leading to almost double increase in the DNA damage yield (~ 1.7-1.8 times). Further increasing the NaCI concentration leading to disruption of the structure of nucleosomes (1.2 M) and almost complete chromatin deproteinization (2 M) increased the yield of DNA damage not such pronounced as expected (~ 2.2-fold at 2 M concentration). Conclusion. The results showed that incubation in NaCI hypertonic solutions significantly increases the sensitivity of lymphocytes to DNA damaging action of free radicals.
Vorobyeva N.Yu., Arkhangelskaya E.Yu., Bushmanov A.Yu., Osipov A.N. Effect of incubation in sodium chloride hypertonic solutions on y-radiation and hydrogen peroxide induced DNA damage in human peripheral blood lymphocytes // Saratov Journal of Medical Scientific Research, Vol. 10, Issue 4, 2014, pp. 735-739

Aim: to study the patterns of changes in the number of DNA double-strand breaks (DSB) in mammalian cells continuously exposed to low dose-rate y- radiation. Material and methods. Chinese hamster lung fibroblasts (V79) were used in this study. The y- irradiation of cells at a dose rate of 0.1 mGy/min was performed using the «Gamma-Panorama» unit (Cs-137). The fluorescence immunoassay of the phosphorylated H2AX-histone (y-H2AX) foci was used to investigate the DNA DSBs formation. Frequency of apoptotic cells was evaluated using «DNA halo» assay. 5 (6) — chloromethyl-2,7-dichlorodihydrofluorescein diacetate was used to estimate the reactive oxygen species (ROS) production. Results, it was showed that continuous low dose-rate irradiation of Chinese hamster V79 cells induces an increase of the y-H2AX foci number and ROS production rate at the early stages of exposure time (6-24 h, doses 3.6-14.4 cGy), while increasing exposition time and, therefore, the radiation dose (48-72 h, 28.8-43.2 cGy) caused a decrease in these endpoints to almost the control level. There was observed no significant changes in the frequency of apoptotic cells. Conclusion. It is assumed that the processes causing the DSB amount changes in mammalian cells continuously exposed to low dose-rate y-radiation are associated with the development of oxidative stress and subsequent activation of cellular antioxidant defense systems.
Ozerov I.V., Bushmanov A.Yu., Anchishkina N.A., Guryev D.V., Pustovalova M.V., Smetanina N.M., Arkhangelskaya E.Yu., Vorobyova N.Y., Osipov A.N. Induction and reparation of double-strand DNA breaks in V79 cells continuously exposed to low dose-rate Y-radiation // Saratov Journal of Medical Scientific Research, Vol. 9, Issue 4, 2013, pp. 787-791