[Effect of temperature on the development of chromosome aberrations in human blood lymphocytes irradiated in pulse and continuous modes at BARS-6 reactor].

Summarized results of 5 repeated experiments of comparative study of radiation effects of the pulse reactor BARS-6 either in a single pulse or a continuos irradiation mode on human lymphocytes are presented. Higher efficiency (30-40%) of continuous irradiation (exposure duration 1 h) rather than pulse irradiation with ultra-high dose rates (1-2.5) x 10(6) Gy/min (pulse duration 65 micros) was confirmed. The efficiency ratio did not depend on the temperature, 20 degrees C or 0 degrees C, during the exposure. Cell repair system and chromatin conformation influence on the results obtained is discussed.

[The comparative analysis of gene and structural somatic mutations in inhabitants of Orel district areas contaminated with radionuclides as a result of Chernobyl accident].

The results of comparative analysis of gene and structural mutations found in peripheral blood lymphocytes of inhabitants of Orel district areas contaminated with radionuclides as a result of Chernobyl accident are presented. The average level of 137Cs contamination in those areas ranged about 22-113 kBq/m2. In the study group was found the enhanced frequency of somatic cells with gene and structural mutations compared with laboratory control level by synchronous applying a T-cell receptor (TCR) loci mutation assay and cytogenetic analysis of unstable aberrations. The case-control comparison was carried out using the measured mutation frequencies and cases of various thyroid gland sickness recognized by ultrasonic examination. The cytogenetic assay did not show the statistical difference between healthy group and subjects with thyroid gland sickness. The average frequency of TCR loci mutation cells in the subjects with thyroid gland sickness was found to be statistically higher comparing with healthy persons. This finding was true for each study region and for Orel district in total. The subgroup of subject exposed in utero in 1986, soon after accident was analyzed. Both cytogenetic and TCR loci mutation assays shown enhancement of average mutation frequency in somatic cells in the subjects of this subgroup with thyroid gland sickness comparing with healthy persons.

[Cytogenetic effect of the pulse reactor BARS-6 continuous or one-time irradiation with ultrahigh dose rate on human lymphocytes].

The results of the comparative study of radiation effects of the pulse reactor BARS-6 either in single pulse or continuos irradiation mode on human G0 lymphocytes are presented. Under identical doses the cytogenetic efficiency was observed to be higher for continuous irradiation (1 hour) than for single pulse irradiation with ultrahigh dose rate (0.5-3) x 106 Gy/minutes (pulse duration 65 x 10(-6) s). The difference averaged about 37% on total aberration frequency and 27% on the sum of dicentrics and centric rings. The influence of the dose rate and of the mixed gamma-neutron irradiation on the obtained results is discussed.

[Comparative investigation of structural and gene somatic mutations in workers of nuclear chemical plants. I. A study of stable and unstable chromosome aberrations].

A study of frequency of unstable chromosome aberrations in 50 workers of nuclear chemical plants in remote period after beginning or finishing professional contact with ionizing radiation was carried out. 14 persons from this cohort were mainly whole-body exposed to external gamma-rays and 36 were exposed to combined external and internal radiation from incorporated Pu nuclides. In results of this irradiating practically every subject had a chronical radiation sickness. In the 1-st group the frequency of unstable aberrations varied from 0.2 to 3.6 per 100 cells and exceeded reliably control level in 5 persons. In the 2-nd group the frequency of unstable aberrations varied from 0 to 11.6 per 100 cells and exceeded reliably control level in 20 examined workers. The FISH study of frequency of stable aberrations was performed in 13 subjects who were exposed to combined external and internal radiation. Total frequency of complete and incomplete translocations varied from 0.6 to 18.5 aberrations per genome per 100 cells and reliable exceeded control level in 9 subjects. Non-random participation in exchange rearrangements (translocations) was revealed for used set of chromosomes (2, 3 and 8).

[Results of dynamic cytogenetic study of children and teenagers living in areas, radioactive by contaminated after the Chernobyl accident].

Results of multiyear cytogenetic study of children and teenagers living in areas, radioactive by contaminated after Chernobyl accident, were adduced. Mean density of 137Cs contamination in two compared living areas were 111 and 200 kBq/m2 and mean external doses accumulated for 1986-2001 were 6.7 and 11.4 mGy correspondingly. Averaged thyroid doses receives by subjects of all age groups in the second area were approximately 1.5 times higher than in the first area; in the youngest group (0-1 year) the doses were 114.3 and 174.3 mGy. During 17 years cytogenetic investigation approximately from 30% to 60% of examined persons were observed the increased level of chromosome aberrations in lymphocytes of peripheral blood. Average frequency of unstable aberrations (acentrics, dicentrics and centric rings) constituted about 0.4 per 100 cells (0.22 per 100 cells in controls) during all period of observation. Level of marker aberrations (dicentrics and centric rings) was increased almost all times of study and varied within 0.04-0.19 per 100 cell (0.03 in control group). The parallel investigation of frequency of stable aberrations by FISH method showed up their level about 3 times exceeding observed dicentrics level. Comparably higher indexes of cytogenetic disturbances were revealed in group exposed in utero during period of accident.

[Retrospective dose estimation in remote period after exposure using different biological methods]. / Retrospektivnaia otsenka doz v otdalennyi postraditsionnyi period raznymi biologicheskimi metodami.

Investigation of application of chromosome aberrations of lymphocytes in peripheral blood for biological dosimetry purposes in remote (up to 40 years) period after acute exposure to doses of 1 Gy and more was carried out. The comparative analysis of frequency of unstable and stable (using FISH and G-banding methods) aberrations was performed for 24 subjects accidentally exposed to radiation on nuclear submarines during 1961-1985. Statistically significant increasing of frequency of dicentrics and centric rings was determined in the exposed subjects in remote period after exposure to compare with controls. Their sum frequency in the exposed group varied depending on ARS heaviness from 0.1 to 1.0 aberrations per 100 cells. In control group it was from 0 to 0.2 correspondingly. Translocation frequency (complete + incomplete) fixed by FISH method (2, 4, and 12 chromosomes) varied within the limits of 0.2-16.0 for exposed subjects and 0.3-1.26 translocations per genome per 100 cells for controls. Some examined persons (5 subjects) exposed to accident in 1985 had results of analysis of unstable chromosome aberration in acute period after exposure that allow to estimate obtained doses by dicentrics frequency which having good correlation with ARS heaviness. Individual dosed using traslocation frequency were defined retrospectively in 11 from 21 exposed persons. They correlate with calculated physics doses and doses estimated by haematolotical parameters in acute period and also doses obtained by ESR spectroscopy of tooth enamel in remote period.

[The results of the cytogenetic examination of children and adolescents living in radionuclide-contaminated regions of Kaluga Province]. / Rezul'taty tsitogeneticheskogo obsledovaniia detei i podrostkov, prozhivaiushchikh v zagriaznennykh radionuklidami raionakh Kaluzhskoi oblasti.

After the Chernobyl accident in a period from 1989 to 1992 blood samples were collected and analysed for chromosomal aberrations in lymphocytes from 490 children born and living continuously in two districts of Kaluga Province with radioactive contamination. The results of cytogenetic examinations show the frequency of unstable aberrations in children from Zhizdra District to be higher than that in children from Ulyanovo District and in the control group. No correlation was found between the thyroid absorbed doses ranging from 0 to 5 Gy and the aberration frequencies. No differences in chromosomal aberration yields were observed in children born before or after the Chernobyl accident. Repeat examinations of the same children cohorts revealed no significant changes with time in the level of unstable aberrations.

[The results of the cytogenetic examination of the inhabitants of population centers adjacent to the Semipalatinsk nuclear testing grounds (at the period of the work of the interdepartamental commission in 1989)]. / Rezul'taty tsitogeneticheskogo obsledovaniia zhitelei naselennykh punktov, prilegaiushchikh k Semipalatinskomu ispytatel'nomu iadernomu poligonu (v period raboty mezhvedomstvennoi komissii v 1989 g.).

Within the frames of activity of joint commission the cytogenetic studies of 98 persons from different areas of Semipalatinsk Province have been carried out in 1989. The studies revealed the higher level of chromosome aberrations in the settlements adjacent to firing ground. The possible connection of discovered cytogenetic lesions to the influence of radiation aftermath of ground and air nuclear weapon test is discussed.

[The results of the cytogenetic examination of children and adolescents living in radionuclide-contaminated regions of Bryansk Province]. / Rezul'taty tsitogeneticheskogo obsledovaniia detei i podrostkov, prozhivaiushchikh v zagriaznennykh radionuklidami raionakh Brianskoi oblasti.

The paper presents the data on cytogenetic studies of 663 children inhabited radionuclide contaminated territories of Bryansk Province. Statistically significant difference with control was observed only for the territory with the highest radioactive contamination level of 137Cs (1000 kBq/m2). For two other territories with lesser contamination (100 and 700 kBq/m2) the rate of chromosome aberrations is nearly the same and does not differ significantly from control one. No difference in the level of cytogenetic damage was discovered for children affected by radiation pre- or postnatally.

[Effect of hyperthermia on the yield of chromosome aberrations during the irradiation of human G1-stage lymphocytes with 252Cf and 60Co sources of various dosage intensities]. / Vliianie gipertermii na vykhod aberratsii khromosom pri obluchenii limfotsitov cheloveka v stadii G1 istochnikami 252Cf i 60Co raznoi moshchnosti dozy.

A study was made of the regularities of structural chromosome damages in human peripheral blood lymphocytes during irradiation at the G1 stage with 252Cf and 60Co sources in dose rates of 0.035 and 0.35 Gy/min at doses of 0.27-3.1 Gy. In 252Cf radiation, the frequency of chromosome aberrations at the G1 stage was described by linear dose-effect ratio in both dose rates and did not depend on a dose rate in the studied dose range. The RBE of 252Cf radiation at the G1 stage grew with a decrease in a dose and dose rate. Postradiation hyperthermia caused less noticeable enhancement of the effect of 252Cf radiation (approximately 10%) as compared to that of 60Co radiation (approximately 30%).

[Influence of the dose rate and postradiation hyperthermia on the cytogenetic effect of irradiation of cells in the G0 stage by 252Cf and 60Co sources]. / Vliianie moshchnosti dozy i postradiatsionnoi gipertermii na tsitogeneticheskii éffekt pri obluchenii kletok v stadii G0 istochnikami 252Cf i 60Co.

The paper is concerned with the results of a comparative study of radiation injury of chromosomes of human lymphocytes at the G0 stage resulting from the influence of 60Co gamma quanta and high activity 252Cf radiation sources and depending on a dose and dose rate; with the potentialities of modifying a cytogenetic effect of irradiation by postradiation hyperthermia of cells. It has been shown that at the G0 stage of a cell cycle the frequency of chromosome aberrations does not depend on the dose rate of 252Cf radiation within the range of 0.0035-0.35 Gy/min. by the neutron component. Linear correlation between the frequency of induced chromosome aberrations and a dose was observed within a dose range of 0.27-3.1 Gy. Thus, a conclusion is that postradiation hyperthermia at the G0 stage does not almost influence the frequency of chromosome aberrations during 252Cf radiation, and increases it insignificantly during 60Co gamma-radiation.