[Genotype dependence of cytogenetic and epidemiological characteristics in the liquidators of the accident at the ChNPP].

The dependence of the level of unstable chromosome aberrations and nononcological diseases on the genotype in 57 liquidators of the ChNPP accident was studied. Candidate genes presumably affecting radiosensitivity were highly polymorphic loci of xenobiotic detoxication genes (glutathione-S-transferases GSTM1, GSTT1, GSTP1) and the 5,10-methylenetetrahydrofolate reductase gene (MTHFR) involved in DNA methylation and synthesis. An increased frequency (0.014 +/- 0.001 per cell) of unstable chromosome aberrations, including radiation-specific dicentrics and centric rings (0.0015 +/- 0.0002 per cell), has been found to be preserved in the group of liquidators examined in 2006-2007. No associations of polymorphism for each of the studied genes with cytogenetic parameters were revealed. Increased frequencies of chromosome aberrations were recorded in homozygous carriers of a deletion at the GSTM1 locus in combination with homozygosity for minor alleles at the MTHFR and GSTP1 loci (p = 0.00002 and p = 0.0233, respectively). The number of homozygous carriers of the minor allele GSTP1 was increased among patients with chronic obstructive pulmonary disease and in liquidators with acute circulation disturbances (p = 0.014 and p = 0.04, respectively). Double homozygotes for GSTM1 and GSTT1 deletions were significantly more frequent among subjects with benign tumors (cysts, polyps, p = 0.015) and with benign thyroid tumors (p = 0.017). This genotype has proved to be protective for patients with severe cardiovascular diseases (acute circulation disturbances, p = 0.027).

[The theory and practice of constructing calibration curves in biodozimetry].

The methodical peculiarities of experimental construction of regression "dose-effect" relationships used for the dose reconstruction are discussed. The method of computer simulations is applied to study the efficiency of different statistical procedures for plotting regression curves as well as the dependence of errors in dose prediction on the volume of examined material and on the choice of doses for a calibration curve. The causes of essential variability of calibrations obtained by different teams of researchers are discussed. A number of methodical recommendations is given for statistical processing of cytogenetic data. The procedure of constructing calibration dose dependence of the frequency of dicentrics on the basis experiments with in vitro gamma-irradiation of lymphocytes from blood samples of 5 donors is considered in detail. The expressions for statistical errors occurring in the dose reconstruction made on the base of the frequency of aberrations were derived and checked by the computer experiment.

[The problem of the transgeneration phenomenon of genome instability in sick children of different age groups after the accident at the Chernobyl Nuclear Power Plant].

A complex genetic examination of children which belong to two cohorts and their parents were carried out. The first cohort included children and constantly living on territories contaminated with radionuclides (Novozybkov district, Bryansk region). They were subdivided in groups according to the ontogenetic age periods of development of their parents at the time of the Chernobyl accident. In the children born in 1986-1995 the level of aberrant genomes is significantly higher as compared to the control (p < 0.001). In children born in 1998-2002 the differences are insignificant (p > 0.05). The frequency of aberrant genomes had a tendency to decrease with the period of time between the birth date of a child and the moment of the accident. Analysis of the results of cytogenetic investigation for the same living on territories with different densities of radioactive contamination (zone I-- 627-688 kBq/m2, 137Cs and zone II-- 135-402 kBq/m2, 137Cs) revealed insignificant differences in the spectrum and average frequencies of chromosome aberrations. The second cohort included children born in 1987-1991 and 1993-2002 from irradiated fathers (Chernobyl clean-up workers) and unirradiated mothers living on territories without radionuclide contamination. These children also displayed increased frequencies of aberrant genomes as compared to the control (p < 0.001). The analysis of the dynamics years of birth of cytogenetic disturbances in the same cohorts of children showed the average frequencies of aberrant genomes remain higher than the control level. In most of the children of both cohorts the repair synthesis of genome DNA by gamma- and UV-radiation is reduced as compared to one in the children from the control group.

Human cytogenetic consequences of the Chernobyl accident.

The frequency of chromosomal aberrations was evaluated in more than 500 liquidators of the Chernobyl accident. The 'sarcophagus' builders and the dosimetrists showed the highest frequency of aberrations per 100 cells: 3.24 +/- 0.25 and 3.11 +/- 0.43. For Chernobyl Atomic Power Station staff members the mean frequencies of aberrations per 100 cells was 2.37 +/- 0.20. The mean yields of aberrations in the other groups was between 1.31 and 1.47 per 100 cells. If the mean frequencies of aberrations are converted into equivalent whole body doses, values between 136 and 414 mGy are obtained. Especially in the group of 'sarcophagus' builders, the yields of aberrations varied interindividually and corresponded to equivalent whole body doses of up to about 2 Gy.

[The cytogenetic effects in the population of the Altai Territory subjected to ionizing radiation exposure as a result of the nuclear explosions at the Semipalatinsk proving grounds]. / Tsitogeneticheskie éffekty u naseleniia Altaishogo kraia, podvegshegosia vozdeistviiu ioniziruiushchikh izluchenii v rezul'tate iadernykh vzryvov na Semipalatinskom poligone.

The cytogenetic examination of 178 persons living in seven settlements of the Altai region exposed to ionizing radiation during Semipalatinsk nuclear tests in 1949-1962 was carried out. It was shown that more than 80% of absorbed dose was due to the first nuclear explosion in 1949. The frequency of chromosome aberrations (dicentrics and rings) significantly exceeded the control level. The linear correlation between the dicentrics and rings frequency and absorbed dose was found. The cells with more than one aberrations were revealed in irradiated persons. This is supposed to be the result of 239Pu alpha-radiation.

[The cytogenetic effects in persons who suffered as a result of the accident at the Chernobyl Atomic Electric Power Station]. / Tsitogeneticheskie éffekty u lits, postradavshikh v rezul'tate avarii na Chernobyl'skoi AES.

Frequency of chromosome aberration was evaluated in 537 persons taken part in amelioration after the accident. The highest rate of aberration was found in covering builders and dosimetric: 3.24 +/- 0.25 and 3.11 +/- 0.43 per 100 cells, respectively. The mean rate of aberrations among the Chernobyl NPP staff was 2.37 +/- 0.20 per 100 cells, in the other examined groups the mean yield of aberration varied from 1.31 to 1.47 per 100 cells. The found aberration rates correspond to the equivalent whole body doses in the range from 131 to 515 mGy as evaluated by the established dose-response curve. In the group of covering builders the individual aberration rates varied more markedly, and corresponded to the equivalent whole body dose up to about 1 Gy. Slides of 27 individuals were checked by an automated dicentric scoring system. The results showed a satisfactory correlation between the frequencies of dicentrics per chromosome detected by routine and computer methods.