Cytogenetic effects in human as the result of the Chernobyl accident

The Chernobyl accident significantly complicated the ecological situation in Ukraine. The existing environmental pollution, which was already rooted in the background, ensures for the most part that the Ukrainian population comes into contact with one of the most powerful universal mutagens - ionizing radiation. This can cause genetic damage in all living beings, including human. As such, it is essential that the Chernobyl accident victims be medically monitored using cytogenetic monitoring – the study of the frequency and spectrum of chromosome aberrations in human peripheral blood lymphocytes with the help of classical (conventional cytogenetics, G-banding analysis) and new (FISHWCP) research methods

Radioinduced Bystander Effect Revealed in vitro and in vivo In Mixed Human Lymphocytes Culture

The new methodic approach to the investigation of radioinduced bystander effect in somatic human cells with the help of G-banding cytogenetics had been elaborated. The frequency of chromosome aberrations had been studied in proposed by us model system - mixed human peripheral blood lymphocytes culture consisted from cells differed on cytogenetic sex markers (XX, XY) and some morphological chromosome peculiarities. 88 cultures (separate and joint) from 5 couples of donors had been established and 9234 G-banded metaphases had been scored. It had been shown that joint cultivation of intact lymphocytes did not influence upon background frequency of chromosome aberrations in mixed culture. Under joint incubation of X-irradiated in vitro (in doses 250 and 1000 mGy) and intact lymphocytes the dose-dependent interaction between marked cellular population and untargeted cells had been established under both doses mean-group cytogenetic effect in bystander cells (4.31 and 6.13 of chromosome aberrations per 100 metaphases) that cultivated with irradiated ones (6.99 and 21.19 of chromosome aberrations per 100 metaphases) elevated their background level (2.27 per 100 metaphases). In mixed cultures established from unexposed donors and Chernobyl liquidators (with radiation doses in range 1010-2370 mGy ) the frequencies of aberrations in irradiated cells were 5,21±0,89 per 100 metaphases, in bystander cells - 4,05±0,64 per 100 metaphases (under 5,63±0,98 and 1,73±0,65 per 100 metaphases in separate cultures). The difference between spectrum of aberrations in exposed and intact cells had been established both in vitro and in vivo - in targeted cells specific cytogenetic markers of irradiation dominated (unstable and stable chromosome exchanges), as well as in bystander cells simple aberrations (chromatid breaks and terminal chromosome deletions that can be consider as the markers of chromosome instability) mainly induced. All cytogenetic effects mentioned above had been characterized by essential interindividual fluctuations. Data received confirmed as the reality of bystander effect in vitro and in vivo as well as the possibility of the revealing of such effect in proposed by us mixed human peripheral blood lymphocytes model system

Chromosome Sensitivity to Bleomycin in Peripheral Blood Lymphocytes from Unexposed and Irradiated Persons

With the help of modifying "G2-bleomycin sensitivity assay" (treatment of human peripheral blood lymphocytes culture in late post-synthetic phase of mitotic cycle by bleomycin in concentrations 0,05 and 5,00 mcg/ml) the investigation of hidden chromosome instability in 9 unexposed donors as well as in 32 persons with different intensity of radiation exposure (patients recovered from acute radiation sickness - ARS and Chernobyl liquidators) had been fulfilled. The basic criterion of chromosomes sensitivity to bleomycin exposure the total frequency of chromosome aberrations, mainly acentric fragments had been considered. In all examined groups the individual levels of chromosome aberrations under identical mutagenic exposure varied in wide range and didnt depend on their initial values in intact cultures. In control donors the mean-group frequencies of chromosome aberrations were 10.37+0.66 (3.0 - 32.0) and 15.54+0.78 (5,0 - 35,0) per 100 cells, additions to background rate of aberrations were 9,14 and 14,31 per 100 cells under bleomycin exposure in concentrations 0.05 and 5.00 mcg/ml, accordingly. Among control donors three hypersensitive persons had been identified with aberrations rate 35.0, 34.0 and 16.0 per 100 cells that can be considered as genetically caused phenomenon. Similar situation had been determined in 10 liquidators with low radiation exposure - the mean-group frequencies of chromosome aberrations were 11.26+0.63 (2.3 - 34.0) and 15.10+0.79 (3.0 - 34.5) per 100 cells, above-background level of aberrations were 9.14 and 14.31 per 100 cells under bleomycin exposure in concentrations 0.05 and 5.00 mcg/ml, correspondingly. In liquidators group three hypersensitive persons had been identified with aberrations rate 34.5, 20.0 and 19.3 per 100 cells. In 19 ARS patients increased mean-group frequency of aberrations induced by bleomycin in both concentrations had been revealed - 16.80±0.50 (8.7 - 38.2) and 28,04±0,63 (6.0 - 60.0) per 100 cells with addition to background aberrations level 13.47 and 24.71 per 100 cells, accordingly. 13 persons with increased chromosome instability (from 22.2 till 60.0 aberrations per 100 cells) had been found. The data received permit to assume that high radiation doses can modify the inherited human susceptibility to mutagen exposure