[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.

[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.

[Theoretical analysis of the reason for unsatisfactory approximation of experimental data on fractionated effect of gamma-radiation and (or) neutrons on lymphocytes at the G0 and G1 stage]. / Teoreticheskii analiz prichin neudovletvoritel'noi approksimatsii éksperimental'nykh dannykh po fraktsionirovannomu vozdeistviiu gamma-izlucheniia i (ili) neitronov na limfotsity v stadiiakh G0 i G1.

The causes were analyzed of unsatisfactory approximation, based on a mathematical model of cytogenetic effect of interaction of lesions induced by two doses of gamma-radiation and/or neutron in human blood lymphocytes at the stage G0 and G1. For the analysis the published data were used concerning the effect of inhibitors of protein and DNA synthesis on aberration yield in G0- and G1-cell cycle stages at different periods of time after their irradiation with different doses of gamma-rays and neutrons. It is assumed that the cause of the unsatisfactory approximation is the effect of the combined repair of lesions caused by two dose fractions under the process of replication repair caused by the first dose fraction.

[Comparative study of chromosome aberration formation in lymphocytes culture under pulsed and continuous neutron irradiation]. / Sravnitel'noe izuchenie zakonomernostei obrazovaniia aberratsii khromosom v kul'ture limfotsitov cheloveka pri impul'snom i prolongirovannom neitronnom obluchenii.

Frequencies of chromosome aberration induced by prolong (continuous) neutron radiation (dose-rate 0.17 Gy/min) and pulsed neutron radiation with ultra-high dose-rate (1-4) x 10(5) Gy/s have been studied in human blood lymphocytes at G0-stage. It was demonstrated that cytogenetic efficiency of pulsed neutrons (after the substraction of approximately 50% gamma-component from the total dose) was 2 times higher than that of continuous neutron radiation.

[Quantitative patterns in the yield of chromosome aberrations in a human lymphocyte culture with fractionated gamma-neutron irradiation at different stages of the mitotic cycle. The cytogenetic effects at stage S]. / Kolichestvennye zakonomernosti vykhoda aberratsii khromosom v kul'ture limfotsitov cheloveka pri fraktsionirovannom gamma-neitronnom obluchenii v razlichnykh stadiiakh mitoticheskogo tsikla. Tsitogeneticheskie éffekty v stadii S.

Quantitative regularities of the chromosome aberrations yield in the human lymphocyte culture affected by fractionated gamma/neutron irradiation (in the direct and inverse sequences) at a stage of the replicative DNA synthesis (S), with the 1 to 5 h intervals between the dose fractions, were studied. The obtained results on the cytogenetic effect of interaction of damages were compared with those for the stages G0 and G1. In contrast to the latter cases, where occurrence of superadditive effects was high, only subadditive effects were observed for the stage S.

[The approximation of cell distribution by the number of aberrations in the fractionated gamma-neutron irradiation of a human lymphocyte culture at the presynthesis stage (the G0 and G1 stages of the cycle) based on a theoretical model]. / Approksimatsiia raspredeleniia kletok po chislu aberratsii pri fraktsionirovannom gamma-neitronnom obluchenii kul'tury limfotsitov cheloveka v stadii predsinteza (G0- i G1-stadiiakh tsikla) na osnove teoreticheskoi modeli.

A theoretical model is suggested that allows calculating a yield of cells with a number of aberrations caused by fractionated gamma irradiation using the corresponding data for a separate irradiation. The value of a cytogenetic interaction of damages induced by two fractions of irradiation doses was used as a free parameter of the model. In terms of the model, approximation of experimental functions of the cell distribution in a number of exchange aberrations caused by gamma and/or neutron irradiation was made. At a stage G0, with the 1 h interval between the dose fractions, approximation was successful only for irradiation with equal or isoeffective dose fractions; with the interval of 5 h, it was successful for all types of irradiation except for two highest doses of fractionated neutron and gamma/neutron irradiation. At a stage G1, approximation was satisfactory almost for all types of fractionated gamma/neutron irradiation irrespective of the interval between the dose fractions and of a dose of fractionated gamma irradiation with the interval 1 h. For the fractionated neutron and neutron/gamma irradiation at a stage G1, approximation of experimental distributions was unsatisfactory in all the cases.

[Quantitative patterns in the yield of chromosome aberrations in a human lymphocyte culture with fractionated gamma-neutron irradiation at different stages of the mitotic cycle. The cytogenetic effects at stage G1]. / Kolichestvennye zakonomernosti vykhoda aberratsii khromosom v kul'ture limfotsitov cheloveka pri fraktsionirovannom gamma-neitronnom obluchenii v razlichnykh stadiiakh mitoticheskogo tsikla. Tsitogeneticheskie éffekty v stadii G1.

Quantitative regularities of the chromosome aberrations yield in the human lymphocyte culture affected by fractionated gamma/neutron irradiation (in the direct and inverse sequences) at a stage of the presynthesis (G1), with the 1 to 5 h intervals between the dose fractions, were studied. The obtained results were compared with those for the stage G0 described in the previous paper. The cytogenetic effect, with doses and intervals between the dose fractions being equal, depended significantly on a stage of the mitotic cycle of the cells. The effect was opposite for the stages G0 and G1: super- and subadditive, respectively.

[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.

[A comparative study of the frequency of stable and unstable chromosome aberrations in the gamma irradiation of human lymphocytes in vitro]. / Sravnitel'noe issledovanie chastoty stabil'nykh i nestabil'nykh abberatsii khromosom pri gamma-obluchenii limfotsitov krovi cheloveka in vitro.

Comparative studies of the yield of stable and unstable chromosome aberrations have been carried out in human lymphocytes gamma irradiated in vitro within the doze range 0.1--1.0 Gy. It was observed that the yield of unstable chromosome aberrations (dicentrics and centric rings) is satisfactorily described for discovered dose range with linear-quadratic approximation. For stable chromosome aberrations in G-banded chromosome the dose response dependence was less expressed. The studies revealed non-random involvement of different chromosomes in translocations, and the most frequently involved are 1 and 13 chromosomes.

[The quantitative patterns in the yield of chromosome aberrations in a human lymphocyte culture under fractionated gamma-neutron irradiation at different stages of the mitotic cycle. The cytogenetic effects at the G0 stage]. / Kolichestvennye zakonomernosti vykhoda aberratsii khromosom v kul'ture limfotsitov cheloveka pri fraktsionirovannom gamma-neitronnom obluchenii v razlichnykh stadiiakh mitoticheskogo tsikla. Tsitogeneticheskie éffekty v stadii G0.

A study was made of the quantitative regularities of the interaction of cytogenetic damages induced, at the G0 stage of human lymphocyte culture, by fractionated gamma-neutron radiation, within a wide range of doses, delivered in the direct of reverse sequence at the intervals between fractions of 1 and 5 h. The results were compared with those obtained in experiments with single and fractionated gamma- or neutron irradiation within the same dose range.

[A comparative assessment of the changes in absorbed neutron doses and in the frequency of chromosome aberrations in samples of human blood lymphocytes by the depth of the water phantom during irradiation by the biomedical BR-10 reactor beam]. / Sravnitel'naia otsenka izmeneniia pogloshchennykh doz neitronov i chastoty aberratsii khromosom v obraztsakh s limfotsitami krovi cheloveka po glubine vodnogo fantoma pri obluchenii na mediko-biologicheskom puchke reaktora BR-10.

Distribution of the chromosome aberration frequency in human blood lymphocyte samples and absorbed doses have been compared by the water phantom depth during irradiation with 1.5 Gy neutrons (mean energy of 0.85 MeV). There is a good concordance of their depth distribution. The half-fall layer of the absorbed dose within the tissue-equivalent medium is similar (approximately 5 cm) with both measurements done. The aberration frequency in the biological samples placed outside the radiation field in the phantom increases which indicates that the neutron been bounds are indistinct upon passing the tissue-equivalent medium.