Early phenomenon on the potentiation of radioprotective properties of aminothiols (cystamine) during repeated application in the first 7 h of drug’s after-effect by increasing their activity by 2 times was discovered (B.I. Davydov, 1971, M.V. Vasin, V.V. Antipov, 1972). A hypothesis has been proposed to explain this phenomenon. The mechanism of radioprotective properties cystamine is associated with partial neutralization of oxygen effect with the development of reductive stress in the cell, which does not end after the cessation of protective effect of radioprotector. In the body, negative feedback mechanisms are implemented at the cell, which prevent full implementation of naked consequences of reductive stress. In it, the transcription factor HIF-1 plays a key role, which enhances the production of ATP due to glycolysis and, thereby, reduces the burden on oxidative phosphorylation processes under conditions of acute hypoxia with repeated use of cystamine over the first 7 h after the cessation of its radioprotective activity. There is an increase in metabolic shifts in the body with the development of deep hypothermia in animals up to 29°C rectal temperature which can lead to depletion of these restrictive mechanisms and, thereby allowing aminothiol to fully exhibit its protective properties without excluding the increase in its toxicity. In addition, this contributes to a more complete implementation of post-radiation repair of DNA. These processes contribute to a more complete realization of the affected repair of DNA breaks by providing more time for it in conditions of longer hypothermia and mitotic blockade under the action of cystamine.
The dose–effect and radionuclide burden–effect relationships that were set earlier for three types of chromosomal aberrations (dicentrics, stable aberrations and total aberrations) enabled the development of a biodosimetry system. This system is shown to enable estimation of individual doses and of 239Pu body burden among Mayak PA workers due to acute or chronic inhalation of low-transportable plutonium compounds. The relative error of individual radiation doses absorbed in the lungs estimated by the biodosimetry system (based on stable CA and total CA) varied between 5.4 and 83.6
In the second part of the review on estimates of excess relative risks (ERR) per 1 Gy/Sv for mortality from diseases of the circulatory system (ICD-9: 390–459; ICD-10: I00–I99) after irradiation, a combined analysis and meta-analysis was carried out for nuclear industry workers of various countries. The completeness of the sample at the end of 2021 appeared to be exhaustive. The combined analysis of the data consisted in assessing the average for the sample after eliminating outliers from it; ERR per 1 Gy/Sv was 0.20 (95% CI: 0.11; 0.30). The meta-analysis was performed on the full sample, without removing outliers. Some heterogeneity was identified, so a Random effect model was used for the meta-analysis, and the ERR per 1 Gy/Sv was 0.11 (95% CI: 0.01; 0.22). The mean value of ERR per 1 Gy/Sv obtained here only for nuclear industry workers, as well as the result of the meta-analysis, did not differ much from the data of M.P. Little and co-workers (2010–2016) for heterogeneous samples from different populations. At the same time, the data for ‘Mayak’ PA on mortality from circulatory pathologies in general, and not for their individual types, indicate lower risks for external exposure (Azizova TV et al., 2018): ERR per 1 Gy/Sv was 0.04 (95% CI: –0.00; 0.09). All listed risks from the point of view of classical epidemiology, when using the common Monson scale for relative risks (RR), should be considered either ignorable (RR = = 1.0–1.2) or weak (RR = 1.2–1.5). An estimation of the absolute risk of mortality from circulatory pathologies for a hypothetical group of 100,000 nuclear workers who each accumulated a dose of 1 Gy, based on data on the baseline mortality of men from these pathologies for the United States, showed an increase of 1400 deaths over 20 years of employment. However, recalculation for the real average dose accumulated by workers in different countries (31.1 mSv; Koterov A.N. et al., 2021) revealed an insignificant increase in mortality at 0.6% of the baseline level, which risk cannot be taken into account for such multifactorial pathologies. The results obtained in the second part of the presented study: a) reinforce the conclusion made in Report 1 about the advisability of adhering to the dose threshold of 0.5 Gy for circulatory pathologies mortality established by UNSCEAR, ICRP, NCRP, BEIR, etc.; b) they indicate very low, negligible risks of mortality from circulatory pathologies attributed to the radiation factor for nuclear industry workers in recent decades and for most of those even in the previous period; c) they show that for the real activity and health protection of the majority of workers in the nuclear industry, the determination/calculation of the radiation risks of mortality from circulatory pathologies is of an exclusively theoretical nature. These conclusions are important, among other things, for expert advices on establishing the causality of occupational pathologies in nuclear industry workers.
The transformation of the floodplain hydrological regime due to climate change and human activity can significantly impact the bioavailability of long-lived radioactive isotopes of cesium and strontium. A laboratory experiment demonstrated that varying the moisture content of alluvial soil within 40 to 100
The lower threshold of chronic exposure rate values, above which negative radiobiological effects occur, are estimated and compared for mammals with low and high natural life expectancy. A dataset has been prepared containing information on observed radiobiological effects of chronic exposure in mammals depending on the dose rate. The dataset includes 118 records for mammals with high life expectancy and 92 records for mammals with low life expectancy. The data were analyzed with the nonparametric statistics. The lower threshold for deterministic radiation effects of chronic exposure for long-lived mammals is shown to be 0.1 mGy/day with a 95
The study of the complex of EPR characteristics of metabolic reactions involving free radicals and paramagnetic metal complexes revealed a pronounced dose-dependent dynamic SOS response of the most important life support systems of the body under General gamma irradiation. Studies in actively proliferating tissues of the ribonucleotide reductase enzyme using low-temperature EPR spectroscopy and parallel cytogenetic analysis of tissues and blood indicate initial radiation-induced trigger events that initiate the generation of DNA damage in hematopoietic organs. In the mechanism of the anti-radiation effect of radioprotectors, an increase in the activity of ribonucleotide reductase and the induction of deoxyribonucleotide synthesis is necessary for effective damage repair and DNA synthesis in cells of radiosensitive organs. The use of EPR biomarkers allowed us to justify the doses and modes of administration of radioprotectors to obtain optimal radio protection.
A magnetic field can change the biological activity of drugs, which can be used in medicine. Literature data on the increase in biological activity of prepared drugs under the influence of pulsed magnetic fields immediately before their administration have not been found. This paper presents data on the increase in antibacterial activity of benzylpenicillin sodium salt after its treatment with pulsed magnetic field. The aim of the work is to investigate the reasons for the increase in biological activity of benzylpenicillin and to show the changes that occur in the molecule under the influence of a pulsed magnetic field. Exposure to magnetic field was carried out on powdered antibiotic at a magnetic-pulse unit with magnetic field strength H = (0.09–0.82) × 106 A/m. The pulse shape was a damped sinusoid with frequency response f = 40 kHz and f = 51 kHz. The experimental methods of NMR spectroscopy and IR-Fourier spectroscopy were used in the studies. A shift in the values of chemical shifts (δH) and of spin-spin interaction constants (2JHH) in the signals of methylene protons of the benzyl substituent under the influence of the magnetic field was found. Changes were detected by FTIR spectroscopy in the absorption bands of the N–H and C=O bonds of the amide grouping and the carbonyl group of the lactam cycle. The obtained spectral data allow us to conclude that the geometry of the benzylpenicillin sodium salt molecule in the amide fragment has changed under the influence of a pulsed magnetic field, which may be the reason for the enhanced antibacterial activity of the antibiotic.
The production activities of radiopharmaceutical enterprises involve the discharge of technogenic 131I. Based on the example Karpov Scientific Research Institute of Physics and Chemistry (Obninsk), a method for assessing the radioecological situation around the enterprise in long-term dynamics is shown by determining the content of this radionuclide in the components of the natural environment, as well as the dose loads on biota and humans. A model assessment of the average annual volume activity of a radionuclide based on a Gaussian model of scattering and transport of impurities in the atmosphere, allowing us to determine it at any point of the terrain, has been conducted. It was determined that the dose loads on biota varied from 0.5 µGy/day (for bees) to 8.7 µGy/day (for earthworms) and were significantly lower than environmentally safe exposure levels (100 000 and 10 000 µGy/day, respectively). Adult radiation doses ranged from 0.5 to 1.3 µSv/year, which does not exceed the quota of the Karpov Scientific Research Institute dose limit of 300 µSv/year. The necessity of taking into account both the molecular and aerosol forms of 131I in the assessment of the radioecological situation in order to prevent underestimation of the dose load by up to two times is emphasized. The obtained assessments of the radioecological situation around the Karpov Scientific Research Institute in the years 2015–2021 indicate the absence of negative radiation and environmental effects on humans and their environment. The assessment algorithm can be applied to other enterprises producing radioactive iodine discharges.
The study outlines various factors that determine the impact of the accident at the Mayak chemical plant on agriculture and unique characteristics of the radiation levels in the affected region. In order to guarantee preparedness for any operational response, it is crucial to establish an efficient management structure that can make swift and well-informed decisions. Additionally, having access to emergency plans, prognostic calculation tools, and suitable protocols for handling emergencies are equally essential. These crucial elements are all necessary to ensure that any unexpected event can be addressed promptly and effectively. An analysis of protective measures taken at various times after the Kyshtym accident has been carried out. The paper presents the formulated key takeaways from the Kyshtym accident that pertain to emergency preparedness, the execution of organizational and agrochemical protective measures in agricultural production, and the utilization of accumulated knowledge in both science and practical applications.
It is known that ionizing radiation can damage the genetic apparatus of a cell not only through direct exposure, but also through the induction of oxidative stress. Thus, oxidation of guanine (G) nitrogenous base by oxidative stress products can result in G:C>T:A and G:C>C:G type transversions in the tumor growth suppressor gene TP53. Somatic and inherited variants of the TP53 gene, in turn, are of great importance in the development of malignant neoplasms. Therefore, the aim of the study was to analyze the G:C>T:A and G:C>C:G transversions of the TP53 gene in peripheral blood cells of individuals affected by chronic low-dose rate exposure. The paper presents the results of the analysis of the spectrum of TP53 gene sequence variants based on G:C>T:A and G:C>C:G transversions in peripheral blood cells of the Techa Riverside residents of the Chelyabinsk and Kurgan regions affected by chronic low-dose exposure in the 1950s. The range of individual values of the accumulated absorbed dose to red bone marrow due to external gamma radiation and 90Sr ranged from 2.1 to 2742.0 mGy (mean value being 605.4 ± 191.9 mGy (M ± SE)). As a result of the study, 7 different variants of the TP53 gene based on the G:C>T:A and G:C>C:G transversions, which are single-nucleotide substitutions, were identified in the examined individuals. All detected variants were present in the IARC TP53 Database and had no clinical significance as “pathogenic” or “probably pathogenic.” The differences in the frequencies of carriers of detected TP53 gene variants between the comparison group and the main group did not reach a statistically significant level.
Natural species are widely used as pharmaceutical agents for treatment of many human diseases. One of these is the seeds of Nigella sativa and its constituent thymoquinone (TQ). As a biologically active compound, TQ manifests a variety of therapeutic properties, including antioxidant, anti-inflammatory, antitumor and some others. Since TQ is an absorber of free and superoxide radicals, it is a promising natural radioprotector against immunosuppressive and oxidative effects of ionizing radiation. The review presents the data on TQ radioprotective properties and some of the mechanisms of its activity. In addition, TQ exhibits antitumor activity by inhibiting cell proliferation, migration, and invasion. It is known that TQ can induce apoptosis by regulating the expression of pro-apoptotic and anti-apoptotic genes in many types of cancer, but the mechanism of TQ action in oncological diseases has not been fully studied yet. We described in this review the mechanisms of action of TQ as a promising radioprotector and as a future candidate for antitumor therapy.
The results of study of hypermethylation of promoters of the cell cycle genes (RASSF1A, p16/INK4A, p14/ARF, p53, ATM), antioxidant protection (GSTP1, SOD3), and 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, liquidators of the accident at the Chernobyl nuclear power plant, and adult residents of territories contaminated with radionuclides at 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 cytogenetic parameters considered, 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.
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 at 5–15
A statistical model has been developed for reconstructing individualized external exposure doses for people living on a territory contaminated 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
In a series of experiments, the photoprotective properties of ethanol and ethanol–castor compositions based on promising combinations of lichen extracts (1 : 1) were studied in terms of a set of parameters: (1) SPF, λcrit, and UV-A/UV-B in vitro; (2) morphological and functional characteristics of the skin, pro- and antioxidant processes in mouse blood (line Af) after topical application of the compositions and exposure to UV-A/B in vivo. In general, photometric studies showed a very high level of photoprotection in all lichen compositions created, which are close to each other quantitatively and approach the category of “sunscreens.” Compositions based on the combination of extracts “ethylacetate Cladonia arbuscula + methanol Ramalina pollinaria” favorably stand out in terms of the combination “SPF–λcrit–UV-A/UV-B.” According to the biochemical and morphometric parameters, ethanol and a 30
The results of evaluating the therapeutic effectiveness of a composition based on antiradiation serum and metabolic products of bifidobacteria on laboratory animals subjected to experimental combined radiation and thermal effects are presented. In this work 124 mongrel white rats of both sexes with a live weight of 180–220 g were used as a biological model. 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 eight 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 the 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 h accelerated the formation of a burn scab by 1.75 times (p < 0.01), complete rejection of the burn scab increased by 1.15 times (p < 0.05), and 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
This review critically examines published data on parameters characterizing the bioavailability of thorium in the soil–plant system, including thorium distribution coefficients in soil (Kd) and soil-to-plant concentration ratios for thorium (CR). The review notes that the behavior 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 recorded for corn, white rice, and root crops (n × 10–5 to n × 10–4 kg/kg); vegetables, cereals, and fruits occupy an intermediate position in this row. The review also emphasizes the role of foliar contamination of plants and differences in the accumulation of thorium isotopes 228Th, 230Th, and 232Th by plants. It is shown 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.
We analyzed the key stages in the scientific history for electromagnetic field bio-medical effects researches in Russia over 130 years. Has been proven the continuity of scientific knowledge about EMF biological effects and it transmission from one generation of scientists to the next because to exist of scientific schools, the systematic research and national scientific coordination. The main attention is paid to the period of formation of planned EMF health research, when the basic methodological principles were found and so as fundamental scientific basics for understanding the nature of EMF biological effects and their influence for health. The Russian scientists fundamental conceptions about the mechanism of the electromagnetic field biological action and the principles of its hygienic regulation are summarized.
The tool research of electromagnetic fields of industrial frequency and radio-frequency range in by Murino of the Leningrad Region is executed. Steady excesses of admissible level of tension on borders of a sanitary rupture of the high-voltage line of 330 kV are revealed. Excesses of admissible levels of magnetic induction and in the radio-frequency range – energy stream density are not revealed. It is established that the difference of values of electric field strength in 1.8 m from a surface and at the height of 72 m reaches 1–2 orders that can be explained only with the grounding Earth’s surface role. Considerable divergences of the settlement and measured values of tension and magnetic induction are revealed that means insufficiently correct account when calculating electrophysical properties of air. The detailed cards of density of a stream of energy showing a difficult, but steady picture of distribution of values are created. Some elements of territorial structure of electromagnetic fields of radio-frequency range – fragments of rings around base stations of cellular communication, and the auras dated for certain houses are revealed.
The effect of threefold (1 hour a day with an interval of three days) and multiple (8 weeks, 5 days a week, 2 hours a day) pulsed-modulated electromagnetic radiation on the orienting-exploratory response was studied on males and females of Wistar rats by the “open field” method. The animals were irradiated in an anechoic chamber in the zone of the formed wave of the microwave source (a block of 10 generators carrying frequencies from 1 to 4 GHz, the total pulse power density 300 µW/cm2, pulse duration 25 ms, sweep cycles 1–6 Hz, cycle turn-around time 30 s). It was shown that the exposure to such parameters could cause a stress reaction and an impairment of long-term memory in some irradiated animals, female rats being more sensitive to the action of microwaves than males. This reaction was transient and the animal behavior was restored 1.5–2 months after cessation of irradiation. However, there is a danger that in the case of constant exposure to microwaves, which, for example, occurs in mobile users, such behavior deviations may be fixed and clinically significant.
