Radiatsionnaia biologiia, radioecologiia最新文献

Inhibitors of the heat shock protein 90 (HSP90) activity are considered as potential radiosensitizers of tumors with a perspective of their application in radiotherapy. However, there are tumors and tumor cell lines whose radioresistance is not decreased after treatment with the HSP90 activity inhibitors; therefore, a predictive marker is needed, which would allow one to predict the response of target cells. As such a marker, herein it is proposed to use induction of the heat shock protein 70 (HSP70) that is an early cellular response to the HSP90 dysfunction and can easily be immunodetected. It follows from the data obtained that the radiosensitization of HSP90 inhibitor-treated cells occurs only when this treatment causes the prominent induction of HSP70 in them. Determination of this marker enables one: 1) to predict a possibility of radiosensitization of any cells by means of the HSP90 activity inhibitors, 2) to design the inhibitor concentration range upon which the radiosensitizing effect seems likely to occur, 3) to find whether this radiosensitization will be selective towards cancer cells.

The effect of delayed colony appearance by irradiated cells exemplifying genetic instability is confirmed to be more expressed for diploid wild-type yeast cells characterized by a sigmoidal shape of the survival curve and capable of recovery from radiation damage in contrast to isogenic haploid strain incapable of diploid-specific recovery and characterized by the exponential form of the survival curve. The dependence of the delayed appearance of colonies by diploid yeast cells on the dose of ionizing radiation shows more pronounced manifestation after the action of α-particles (RBE = 4.2 ± 0.3) than after irradiation with y-rays. This effect may be associated with the greater efficiency of densely ionizing radiation to produce lethal radiation damage and accompanying sublesions responsible for the delay in the formation of colonies by the cells surviving after irradiation. It is shown that the dependence of the delayed colony appearance by diploid yeast cells on their survival was substantially the same after exposure to sparsely and densely ionizing radiation. Since exposure to ionizing radiation of different quality induced equally effective number of lethal damage and the same survival rates, these data indicate that the identical number of the accompanying sublesions responsible for the delayed colony appearance are produced by irradiated cells.

Regularities of changes in the content of (137)Cs in green fodder during the remote period after the CNPP accident depending on application of agro-technical and agrochemical activities are analyzed. It is revealed that the use of mineral fertilizers reduces receipt of (137)Cs from the soil to forage and further to a food chain. It is also established that agrochemical activities are more effective than agro-technical ones.

As previously indicated, side population cells (side population, SP) of breast cancer line MCF-7 have greater resistance to the action of low-LET radiation compared to other tumor cells (non SP, NSP). One can assume that one possible reason for the high radioresistance of this fraction of tumor cells is the increased expression of different heat shock proteins (HSP) before and/or after radiation exposure. To verify this hypothesis, we investigated the expression of HSP27 and HSP70 in these populations of cells-before and after irradiation at a dose of 5.0 Gy. The study was performed using scanning microscopy for NSP and SP cells after sorting and immunocytochemical staining. A substantial increase of HSP27 and HSP70 in SP cells was found after irra- diation as'compared with the control. In NSP cells the HSP27 level increased in response to radiation exposure, but to a lesser extent than in SP cells, while the content of HSP70 did not change after irradiation. The results confirm the assumption about HSP27 and HSP70 participation in the formation of SP cell radioresistance by the example of MCF-7 line.

Experiments on mice irradiated with γ-rays in a wide range of doses, from 0.5 to 400 cGy and the bone marrow have shown cytogenetic and cytological effects ranging from I cGy dose 24 hours after exposure to radiation. Dose-independent reduction of the number of nucleated cells in the bone marrow, normal or even elevated levels of mitotic activity, and extreme dependence of the type of chromosomal aberrations on the radiation dose with the maximum in the region of 7.5 cGy were observed in the dose range from 1 to 20 cGy. A linear dose-dependent decrease of the cell.number in the bone marrow, a decreased mitotic activity and increased number of aberrant mitosis were marked in the dose range from 20 to 400 cGy. The findings are discussed in terms of their application for explaining the mechanisms of hormesis, adaptive response, as well as the appropriateness of accounting the parameters studied for solving problems of regulation of permissible doses.

On the basis of official statistical data for 1999-2014 the authors assessed the frequency of polydactyly, reduction defects of limbs and multiple congenital malformations in newborns of the Bryansk region living in the areas with different densities of radioactive contamination by long-lived radionuclides cesium-137.(3.0 to 2523.4 kBq/m(2)) and strontium-90 (from 0.02 to 42.5 kBq/M(2)). The findings did not reveal statistically significant differences in the frequency of polydactyly, reduction defects of limbs and multiple congenital malformations in newborns in the South-Western Territories compared with medium-regional values, although the maximum value of the sum of congenital. developmental anomalies (polydactyly, reduction limb defects and multiple congenital malformations) are detected in the above-mentioned most contaminated areas.

The study area is located within the upper Lokna River basin with a catchment area of about 35 km(2). The schematic map of (137)Cs initial fallout after the Chernobyl disaster in 1986 on soil was drawn. The method of selecting reference sites and soil sampling scheme are given in detail-for statistically correct description of radionuclide initial fallout field. 12 soil samples were selected from each of the six reference sites to characterize the average amount of radionuclide in the upper 30 cm of the soil profile. Additionally, some single sampling points were used on erosion-stable areas adjacent or located within the catchment, as well as the "truncated" samples of the radionuclide inventory from the catchment bottom. The cesium soil contamination in 1986 immediately after the Chernobyl accident was restored taking into account the half-life of (137)Cs. The schematic map adequately correlated with the aerial photography data performed by Hydromet in 1986.

Based on the data from the literature the authors analyzed the methods used for the estimation of the risks of plutonium-contaminated areas. The analysis was based on the published data on the measured plutonium concentrations in the air and soil. To calculate plutonium concentrations in the near-surface air layer above the contaminated area a modification of the method of the load estimation from the mass was proposed: instead of the average plutonium specific activity in soil the authors suggested the use of the soil coefficient which consists of the sum of specific activities of every respirable fraction (size 0.05 to 10 μm) multiplied by the percentage of its activity in the total activity of the soil sample. Verification of the proposed method on independent data showed that the calculated values approached the measured ones.

An association between polymorphic variants of key genes of base excision repair (BER) and lung cancer was studied in "Mayak" workers occupationally exposed to prolonged external y-rays and internal α-radiation from incorporated (239)Pu. The study was "case-control". The group of "cases" consists of 75 "Mayak" workers with the verified diagnosis of "lung cancer". At the moment of diagnosis the mean total absorbed dose from external y-rays to whole body was 1.19 Gy; the mean total absorbed dose from internal α-radiation due to incorporated (239)Pu in lung was 0.31 Gy. The group of "controls" includes "Mayak" workers matched by sex and birth year without lung cancer and other cancers during the study period (141 individuals). Increased lung cancer risk was revealed in workers-carriers of homozygous minor genotype of genes OGG] Ser326Cys (OR - 4.67, p = 0.007), APEI Asp148Glu (OR = 1.82, p = 0.063) and XRCC1 Gln399Arg (OR = 2.86, p = 0.026). Increased lung cancer risk was revealed in carriers of different pairwise combinations of minor genotypes of the studied genes of BER or in carriers of pairwise combinations with one homozygous minor mm-genotype and the other homozygous major ww genotype. Thus, OR of lung cancer in carriers of pairwise genotypes of mm genes OGG] Ser326Cys and APE] Asp 148Glu was 12.17.

Implementation of field experiments took place in two sites located in the Bragin district of the Gomel region, Belarus, i.e. a field in the evacuation zone and a private plot of land in a residential area of thedistrict. The objective of the research was to study the levels of radioactive contamination of air due to the dust raised up during crop harvesting operations. Comparative dose assessment was done to assess external exposure and committed effective doses of internal exposure due to inhalation of (241)Am, (238,239+240)Pu, (137)Cs and (90)Sr by agricultural workers involved in dust-generating harvesting operations. According to the results, the dominant contributors (93-97%) to internal exposure of agricultural workers both on a private plot of land and in the area of evacuation, were the transuranic elements (241)Am and (238,239,240)Pu. In the context of the total doses received by the harvest-workers, the dominant contribution belonged to external exposure which was 2-3 orders of magnitude higher than the levels of internal exposure due to inhalation of radionuclides.