Purpose: To estimate the impact of 3H-thymidine on DNA double strand breaks (DSBs) induction in cultured human mesenchymal stem cells (MSC). Material and methods: Isolation and cultivation of human bone marrow MSC was carried out according to a standard procedure. A sterile solution of 3H-thymidine with different specific radioactivity was added to the cell culture and incubated under the conditions of the CO2 incubator for 24 hours. The specific radioactivity of 3H-thymidine in the incubation medium was 50–1600 kBq/ml. To evaluate quantitatively the DSBs, an immunocytochemical analysis of the DSB marker – γH2AX foci histone was used. Additionally, the proportion of dividing cells was estimated using an immunocytochemical analysis of the cell proliferation marker, the Ki67 protein. Results: It was shown that 24 h incubation of human MSC in a culture medium results in a dose-dependent increase in γH2AX foci. There is a linear increase in the foci γH2AX in the range of 50–400 kBq/ml, after which the relative quantitative yield of foci per unit of specific radioactivity begins to decrease. In general, the dose-effect relationship is approximated by the quadratic function y = 3.13 + 50.80x – 12.38x2 (R2 = 0.99), where y is the number of foci γH2AX in the cell nucleus, and x is the specific radioactivity in 1000 kBq/ml. It was found that incubation of human MSC in a culture medium containing 800 and 1600 kBq/ml of 3H-thymidine resulted in a statistically significant decrease in the cells proliferative activity compared to the control of ~1.25 and 1.41 respectively. The peculiar biological limitation of tritium accumulation in the cell nucleus explains well the nonlinear character of the dependence of the formation of DSBs on the specific radioactivity of 3H-thymidine in the culture medium observed in our study. Conclusion: Quantitative analysis of γH2AX foci has proved to be a highly reproducible and highly sensitive method for evaluating the induction of DSBs in living cells under the action of 3H-thymidine. An analysis of the foci of γH2AX will be useful for accurate estimating the quantitative yield of DBS in living cells per dose of 3H-thymidine β-radiation. To do this, it is necessary to make a correct calculation of the doses received by the cells taking into account the microdistribution of 3H-thymidine in the cell volume and its accumulation in the DNA of living cells.

Purpose: A synthetic study of published data on the growth and development of laboratory rats (albino random-bred, Wistar and Long–Evans) depending on the period of their breeding since 1906 was carried out. Material and methods: Data for the dynamics of growth and age periods of rats were used for calculations and general analysis. Results: Acceleration in terms of age–weight indices for strain animals was found: in conditions of complete diets ad libitum the contemporary rats grew several times faster than the bred ones of 1906–1932. For random-bred rats only the tendency to acceleration was obtained. For more than a century, the Wistar males showed an inverse linear correlation between the breeding year and the age (in weeks) at the of the onset of puberty period (according to the Spearman test: r = –0.952; p = 0.00026; Pearson’s criterion: r = –0.950, p = 0.0003). There was also a direct correlation between the body mass of rats at the time of puberty onset and the year of their breeding (according to the Spearman test: r = 0.975; p = 0.005; Pearson criterion: r = 0.927; p = 0.023). The possible reasons for the acceleration of laboratory growth of rats, which are unlikely to be analogous to the factors presumably causing the known ‘growth acceleration’ in humans (changes in natural and artificial lighting, the effect of heterosis, improvement of socio-hygienic conditions, the growth of information flow, warming of the climate, change in the geomagnetic or radiation background, etc.) were discussed. Apparently, in addition to the probability of special and/or subconscious selection during century, the stimulation of rat acceleration may be explained by the ‘increase in living space and resources’ due to improved standards for keeping animals in the modern period (fewer animals in the cage or even an individual cage). In random-bred animals such standards can be apply for economic reasons to a lesser extent. Conclusions: It is concluded that the physiological, anatomical, possibly behavioral and other standards and patterns for strain rats, including, possibly, its radiosensitivity, published even 30 years ago, and especially more than 50 years ago, should be cautiously transferred to the animals grown under present-day conditions.

The article is devoted to development prospects of nuclear medicine in the Russian Federation. One of the first to provide nuclear medicine in Soviet Union was A.I. Burnasyan. He headed the 3d Directorate General of Ministry of Health (the FMBA of Russia at present). The Institute of Biophysics and the Institute of Medical Radiology (Obninsk), was established in the 50s – 60s of the 20th century, laid the foundation for nuclear medicine and developed it. With their efforts, nuclear medicine in USSR has become the world leader. However, in the 1980s – 1990s, there was a serious lag in this area due to radiophobia that arose after the Chernobyl accident, as well as the collapse of the USSR and the severe economic crisis, overcoming which in the beginning of the 21st century made it possible to pay considerable attention to nuclear medicine. Today the FMBA of Russia leads in the development and application of nuclear medicine technology. In the departments of the FMBA of Russia – the Siberian Research and Clinical Center (Krasnoyarsk) and Northern Medical Clinical Center N.A. Semashko (Arkhangelsk) – carries out high-tech diagnostics and treatment of cancer, neurological and cardiac diseases. Currently, in Dimitrovgrad city, the creation of the Federal High-Tech Center for Medical Radiology of the FMBA of Russia (FHCMR, FMBA of Russia) under the state program “Establishment of Federal Centers of Medical Radiological Technologies” is being completed. FHCMR, FMBA of Russia will provide high-tech medical care to the assigned contingent of the FMBA of Russia and the adult population of the Central, Volga, North-West federal districts. In the article noted the need for training specialists in the nuclear medicine. Training of specialists is already being conducted at the Training and Education Center of the Federal Siberian Research and Clinical Center of the FMBA of Russia. An important aspect of the introduction of nuclear medicine technologies and the operation of such centers are issues of legal regulation. The article pays attention to the licensing of nuclear medicine objects in accordance with the requirements of the Federal Law No. 170-FZ of November 21, 1995 “On the Use of Atomic Energy”. The tasks that need to be addressed for the development of nuclear medicine technologies are formulated, including through the implementation of the public-private partnership mechanism, as well as by expanding international cooperation with the EAEU member states.