Purpose: The evaluation of the repair efficiency of DNA double-strand breaks (DSB), proliferative activity and the yield of cytogenetic disorders in human tumor HeLa cells which survived and gave stable growth after acute irradiation at a dose of 15 Gy. Material and methods: HeLa human tumor cell line (cervical carcinoma) was used. Cells were irradiated on an X-ray biological installation RUST-M1 (Russia), equipped with two X-ray emitters, at a dose rate of 0.85 Gy / min, a voltage of 200 kV, a total current of 10 mA, and a 1.5 mm Al filter. To obtain clones of surviving cells (HeLaRR), after acute irradiation at a dose of 15 Gy, cell cultures were incubated under standard CO2 incubator conditions (37 °C, 5 % CO2) for several weeks until well proliferating cells were obtained. Immunocytochemical staining of the foci of the phosphorylated H2AX protein (γH2AX) was used to quantitatively evaluate the residual foci of DNA DSB repair. The micronuclei number was assessed in cytochalasin-B cytokinesis-blocked binucleated cells stained with acridine orange with luminescence microscopy. The doubling time of the cell population was analyzed by the cell growth curves obtained by daily cell counting for five days. The cell cycle stages distribution was assessed by flow cytometry using the propidium iodide dye. All quantitative indicators of the studies were processed using the Student’s t-test for independent samples and the Kolmogorov – Smirnov test. Results: It was revealed that acute irradiation at a high dose leads to the selection of cells with a higher reparative capacity which is confirmed by the low yield of residual foci of DNA DSB repair and MN after testing irradiation at doses of 5 and 10 Gy. A significant decrease in the proliferative activity of cells that survived after acute X-ray irradiation at a dose of 15 Gy was revealed. The doubling time of the population of unirradiated cells at the stage of exponential growth was ~18 hours while for cells that survived after irradiation at a dose of 15 Gy ~42 hours. A change in the cell cycle phases distribution was observed. Conclusion: Thus, acute irradiation at a high dose leads to the selection of cells with a higher reparative capacity which is confirmed by the low yield of residual γH2AX foci and MN after testing irradiation at doses of 5 and 10 Gy. The decrease in proliferative activity was accompanied by a change in the cell cycle phases distribution.

The development of modern electronics, communications, high-tech production and other technologies lead to a significant increase in the intensity of microwave electromagnetic radiation. This article discusses the problem of registration (including biological detection) and protection from microwave electromagnetic radiation. To consider the method of integral biological and instrumental recording of the intensity of microwave electromagnetic radiation and to evaluate the method of protection using a passive multifrequency re-emitter generator with a radio holographic antenna (trade mark EQVILUM). A series of experiments were carried out to determine the number of double-strand breaks in DNA (DS DNA) by the foci of γH2AX repair proteins, to assess proliferative activity and clonogenic ability after 3 hours of exposure to microwave electromagnetic radiation with a frequency radiation of 1200 MHz both with shielding and without it on a culture of human lung fibroblasts (MRC5 line). It is shown that no changes in the level of DS DNA were revealed in experimental cells, however, a decrease in the clonogenic ability of irradiated cells without shielding was observed against the background of their high proliferative activity. The mechanisms of the observed cellular effects formation are unclear and we suppose that they can be associated with both a change in the metabolism of irradiated cells and with the triggering of certain intracellular mechanisms initiated by electromagnetic radiation (EMR). This study made it possible to identify effective ways of integral assessment of the biological effects of microwave electromagnetic radiation as well as ways of protection against it. A film microcircuit – an autonomous module of a passive multi-frequency re-emitter generator with a radio holographic antenna (EQVILUM trademark) has shown its high efficiency in protection against man-made microwave electromagnetic radiation and can be recommended as an additional means of effective protection.