Radiatsionnaia biologiia, radioecologiia最新文献

We investigated the mechanism of UV-radiation influence on trypsin in free and immobilized (on chitosan) states. The catalytic activity of free enzyme under the action of UV-light is subjected to changes to a greater extent than that of the immobilized one. We assume that the photoprotection effect of chitosan is caused for the following reasons: firstly, through interactaction with trypsin molecules chitosan forms a more photoresistant complex as compared to the native protein; secondly, chitosan probably binds the active photopro- ducts of a free radical nature, thus preventing oxidation (destruction) of several amino acids of the enzyme under its UV-radiation.

This paper presents an analysis of the data published in the scientific literature in connection with the prob- lem of forecasting the risk of development of malignant and non-malignant diseases by chromosome aberra- tion frequencies in cultures of human peripheral- blood lymphocytes. This question is closely linked with the concept of a common chromosomal instability. At the end of the twentieth century evidence of the possibility of such forecast for malignant diseases appeared when cytogenetic indices did not exceed control values on the whole. At the same time there are significant uncertainties due to interindividual and intraindividual variability. In addition, there are significant difficulties concerning distinction of chromosome aberrations induced by environmental influences (for example, radiation) and those due to the possibility of internal processes in the body. For non-malignant diseases the applicability of a similar approach to risk evaluation is not sufficiently substantiated.

The ROS concentration and proliferation activity (Ki67 expression.marker) have been studied in the periphery blood lymphocytes of Moscow and Obninsk citizens, donors, Chernobyl disaster liquidators, inhabitants of the region contaminated after Chernobyl disaster (Klincy) and individuals with prostate cancer. It was shown that ROS concentration in lymphocytes of the liquidators and residents of the polluted region was lowered. But in lymphocytes of patients with tumors the ROS content was higher in comparison with the control. The cell content with Ki67 expression in lymphocytes of the individuals resided in the polluted region and tumor patients was lowered.

The biochemical characteristics of Duschekiafruticosa, grown for a long time under a variety of exposure doses of natural background radiation (up to 150 μR/h) was studied. Uranium was found to make the dominant contribution to the y-background exposure doses. The pH-values and the content of organic matter in soils within the surveyed territory remained unchanged. Accumulation of radionuclides of uranium and thorium in the "soil-plant" system was studied. It is shown for the D. fruticosa that U and Th uptake decreased with y-background increasing. Study of anti-free radical and anti-peroxide cells' protection system indicated a balanced activity of prooxidant-antioxidant systems in the cells of the D. fruticosa leaves. The combined effect of incorporated uranium and thorium is accompanied by a significant increase in chlorophyll content in D. fruticosa.

Analysis of recently available archive materials regarding the liquid radioactive waste storage and reprocessing at the "Mayak" Production Association in 1949-1956 has led to a more accurate reconstruction of radionuclide releases into the Techa River. Radionuclide concentrations in the Techa River water, bottom sediments and floodplain soils in 1949-1951 were reconstructed with the use of a purposely-developed Techa River model. Model calculations agree with the measurements of the specific activity in the river water and bottom sediments conducted since 1951. The model output for the (90)Sr concentration in the river water shows a good agreement with the retrospective estimates derived from (90)Sr measurements in teeth and the whole body of the Techa riverside residents. Modeled (137)Cs-contamination of the floodplain shows agreement with the values reconstructed from (137)Cs measurements in the floodplain soils obtained in later years. Reconstructed contamination levels by radionuclides in the Techa River water and floodplain are being used to refine internal and external doses and risk estimates of late effects in the population chronically exposed to radiation.

The quantitative regularities of changes of cancer stem cell (CSC) population were explored after local γ-irradiation of experimental tumors (murine melanoma line B16). CSCs were detected by the ability of these cells to exclude Hoechst 33342 fluorescent dye and to form a so-called side population (SP) under flow cytometry study. In the control group of unexposed mice a positive correlation was found between the proportion of CSCs (SP) and tumorweight at the initial stage of growth (R = 0.77, p = 0.009). In the advanced stages of tumor growth similar relationship was not revealed. Statistically significant increase in the proportion of CSCs (SP) occurred 2-5 days after exposure of tumor to a dose of 10 Gy as compared to control; this index returned to the control level 8 days after irradiation. On the second day after exposure to radiation a linear correlation between the percentage of CSCs and a radiation dose in the range of 2-10 Gy was established (R = 0.98, p = 0.003), confirming a higher radioresistance of this population as compared to other cells not only in vitro (as it was previously shown by us and other authors), but also in vivo. These results suggest the possibility of application of this model system to assess the CSC sensitivity to various antitumor agents in vivo, including preclinical trials, and clarify the details of the practical application of this method.

Radioprotective therapeutic effect of lyophilized extract ofAmaranthus retroflexus on the resistance of the albino laboratory male mice exposed to X-ray radiation at a one-time dose of LD(100/30) is studied. It was established that a 30-day use of a lyophilized extract of the vegetative parts of A. retroflexus at a dose of 50 mg/kg after X-ray exposure increases the survival rate of mice by 80%, enhances the recovery in the radiation period of the number of leukocytes, neutrophils, lymphocytes in the peripheral blood of the animals and the normalization of the intensity of peroxide oxidation of lipids in liver cells. Dose modification factor on the 5th day after irradiation, when using a lyophilized extract, was 1.5 according to the criterion of survival of mice.

The questions of influence of low radiation doses on microcirculation of blood in ontogeny of males from 7 to 27 years are presented in the article. Using the method of laser Doppler ultrasounds, optical oximetry and laser fluorescent diagnostics, we studied the blood perfusion level in the microcirculation system of 315 schoolchildren and students, considered the regulation mechanisms of microcirculation, the level of oxygen saturation of hemoglobin both in the circulation system and mixed blood, the index of oxygen utilization in tissues and the value of fluorescent use of oxygen. We received the information about the changes in the frequency of occurrence of different microcirculation types associated with the age and region of residence. In the case of higher radiation levels we marked a significant increase of individuals with the "extreme" microcirculation type (hypoemic and hyperemic) against the background of the decreased mesoemic type. A special feature of the metabolism process in children, teenagers, and youths is a decrease of the microcirculation density with an increase of the myogenic tone of metaarterioles and precapillary sphincters. The tone of arterioles grows with age. As a result of the limited blood volume, oxygen. is pulled compensatory from blood in larger amounts; it is shown from a significant decrease of the level of oxygen saturation in mixed blood. The strongest differences are shown for the hypoemic and hyperemic microcirculation type. Dwelling on the areas with radio-ecological pressure is accompanied by an increase in the fluorescent index of oxygen use. The level of the total oxygen use in these individuals is higher than in those living in radiation favorable areas.

Technogenic environmental pollution is the factor of destabilization of natural and agricultural ecological systems. Among various kinds of beings agricultural animals are considered as one of the most vulnerable components of ecosystems to the influence of technogenic factors including ionizing radiation. Therefore, the generalization of experimental data and mathematical modeling are necessary to forecast the mortality of irradiated animals. In this research the numerical. parameters of deaths of the dogs with the body weight of 10-12 kg are considered in detail depending on the dose and the dose rate of external irradiation. The verification of the received relationship is carried out. The comparison of LD(50) values for adult sheep, pigs, dogs, donkeys and mice at the fixed dose rate of 4 Gy/h has shown that the most sensitive to the external irradiation are ruminants - sheep, followed by dogs, donkeys and pigs, and rodents - mice close this series.

The dose-responses of micronuclei (MN) in binucleated (BN) and mononucleated (MONO) lymphocytes cultivated with cytochalasin B (CBMN-assay) were studied. Irradiation of lymphocytes was performed in vitro (donor A) at the single dose of 1 and 2 Gy of (60)Co y-rays, or in vivo, during whole-body exposure of a cancer patient (donor B) to (60)Co γ-rays each day at a single dose of 0.115 Gy up to a total dose of 1.15 Gy. The linear dose-response for MN was determined in both BN and MONO lymphocytes of donor B. It means that when CBMN assay is applied, the MN in MONO cells represent those preexisted in vivo before each exposure. On the contrary, in lymphocytes of donor A irradiated in vitro an essential elevated MN yield with an - increased dose was observed only in BN lymphocytes. A slight dose dependent elevation of MN in MONO cells seems to be due to either their division before cytochalasin was introduced in the culture medium or their insensitivity to the CB block of cytokinesis.