Vol 64, No 4 (2024)

The results of the study of hypermethylation of promoters of the cell cycle genes (RASSF1A, p16/INK4A, p14/ARF, p53, ATM), antioxidant protection (GSTP1, SOD3), estrogen receptor (ESR1) are summarized in individuals exposed to chronic or fractionated irradiation in the range of small and medium doses (101 people, 24–78 years old: the liquidators of the accident at the Chernobyl nuclear power plant and adult residents of territories contaminated with radionuclides, 135–688 kBq/m²), in the aspect of the relationship of these epigenetic modifications with the cytogenetic status of the individual. Multiple regression analysis showed that the frequency of both simple and complex exchange aberrations of the chromosomal type is associated with the methylation status of the complex of the studied genes (β = 0.504, p = 1.9E-7 and β = 0.349, p = 3.6E-4, respectively), but not with age (β = -0.122, p = 0.178 and β = 0.153, p = 0.109). In general, highly significant differences were demonstrated between groups of exposed individuals with different epigenetic status (number of hypermethylated genes) for all considered cytogenetic parameters, with the exception of chromatid-type aberrations (Kruskal–Wallis test: p = 2E-4 and p = 5E-8 for the total frequency of cytogenetic disorders and rearrangements of the chromosomal type, respectively). The level of cytogenetic disorders of the chromosomal type increases with an increase in the number of methylated genes in irradiated individuals. The data obtained may point to general patterns in the mechanisms of induction and preservation over the years of the considered genetic and epigenetic effects of radiation.

To date, natural species are widely used as pharmaceutical agents for many human diseases. One of these is the seeds of Nigella sativa and its constituent thymoquinone (TQ). Being a biologically active compound, TQ has a variety of therapeutic properties, including antioxidant, anti-inflammatory, antitumor and a number of others. TQ is an absorber of free and superoxide radicals, therefore it is a promising natural radioprotector against the immunosuppressive and oxidative effects of ionizing radiation. The review presents data on the radioprotective properties of TQ and some mechanisms of its activity. In addition, TQ exhibits antitumor activity by inhibiting cell proliferation, migration and invasion. Despite the fact that TQ induces apoptosis by regulating the expression of pro-apoptotic and anti-apoptotic genes in many types of cancer, the mechanism of action of TQ in oncological diseases has not yet been fully studied. Thus, this review highlights the mechanisms of action of TQ as a promising radioprotector and as a future candidate for antitumor therapy.

A statistical model has been developed for reconstructing individualized external exposure doses for persons living in a contaminated territory with radionuclides. The basis of the model is the data of individual dosimetric control of external exposure doses of more than 35,000 residents of the Gomel region and informative factor-signs that influence the formation of an individual external exposure dose. The model has a high degree of adequacy, as evidenced by the adjusted coefficients of determination from 0,71 to 0,74. For the adequacy of the application of the model for each calendar year, a coefficient was introduced that determines the decrease in the external exposure dose over time. The calculated values of external exposure doses, taking into account the factor, correlate with the data of individual dosimetric control, the deviation of the calculated values is ± 9%. Verification of the model was carried out on the generated control sample, the estimation error was ~10%. The developed model allows, with high accuracy and the least error, to reconstruction the individualized doses of external exposure of people living in a contaminated area, employed in various social spheres.

The paper presents the results of evaluating the therapeutic effectiveness of a composition based on anti-radiation serum and metabolic products of bifidobacteria on laboratory animals subjected to experimental combined radiation and thermal effects. 124 mongrel white rats of both sexes with a live weight of 180–220 g were used as a biological model in the work. The simulation of radiation damage to the body was carried out by a single external irradiation of animals on a Puma gamma installation with a ¹³⁷Cs radiation source with an exposure dose of 8.5×10^–2 A/kg in an absorbed dose of 7.5 Gy. Thermal injury was inflicted by applying a brass plate heated to 200°C with an area of 4.9 cm² with a retention exposure of 8 seconds to the trimmed area of the upper third of the thigh, inducing a grade III burn. The effectiveness of the therapeutic drug was evaluated according to the following criteria: changes in the titer of the compliment, the concentration of radiotoxin and thermotoxin, changes in the methodological parameters of peripheral blood, the degree of burn damage, survival and life expectancy of fallen animals. The results of tests evaluating the therapeutic effectiveness of the tested composition showed that a single subcutaneous injection of a medicinal product at a dose of 20 mg/kg followed by application of an anti-burn ointment based on bee podmore and St. John’s wort oil at intervals of 24, 48 and 168 hours accelerated the formation of a burn scab by 1.75 times (p < 0.01), complete rejection of the burn scab — by 1.15 times (p < 0.05), the complete healing of the burn wound accelerated by 1.18 times compared with the control groups, thereby increasing the survival rate to 87.5% (p < 0.05) of animals exposed to two-factor exposure to the affected factors, while increasing the average life expectancy to 28.0 days versus 6.5 days in the control (irradiation + burn).

The content of ¹³⁷Cs and ⁹⁰Sr forms in sod-podzolic automorphic and semi-hydromorphic (gleamy) soils of different granulometric composition (loamy, sandy loam, sandy) was studied. It was found that during the long post-accident period, a transformation took place in the soils of the forms ¹³⁷Cs and ⁹⁰Sr, and a dynamic equilibrium in their content occurred. The content of ¹³⁷Cs in the form available to plants is currently an insignificant proportion — 5-15%. On the contrary, ⁹⁰Sr compounds are mainly found in readily available forms, amounting to 60 to 75% in sod-podzolic soils, on average — 67%. This determines its high transitions into plants, especially on mineral soils.

This review critically examines information on parameters characterizing the bioavailability of thorium in the soil–plant system, including thorium distribution coefficients in soil (K_d) and soil-to-plant concentration ratios of thorium (CR). It evaluates data from international projects summarizing information on thorium migration in the environment, as well as current research on thorium accumulation by plants. The review notes that the behaviour of thorium in the terrestrial environment is largely determined by its low mobility in soil. Concentration ratios of thorium accumulation by plants are relatively low: the highest CR values are observed for natural grass vegetation (n×10^–2 kg/kg), while the lowest values are noted for corn, white rice, and tubers (n×10^–5 — n×10^–4 kg/kg). The review also highlights the role of foliar contamination of plants and differences in the accumulation of thorium isotopes ²²⁸Th, ²³⁰Th, and ²³²Th by plants. It concludes that the dependence of CR on the concentration of thorium in the soil is nonlinear, which limits the use of these data for radiological assessments without supplementary information.