[Comparative analysis of cytogenetic examination of control groups of subjects carried out in different Russian laboratories].

The incidence of unstable chromosome aberrations in peripheral blood lymphocytes from unirradiated control subjects was analyzed using cytogenetic data obtained from 9 cytogenetic laboratories located in Moscow, St.-Petersburg, Obninsk, and Dubna (Russia). The objective of this study was to estimate the level and spectrum of spontaneous chromosome aberrations in human lymphocytes. 1140 blood samples were taken from 1112 subjects (594 men and 546 women) aged 1 to 72. The total metaphase number was 466795. The uniform Giemsa method for peripheral blood lymphocyte cultures was used. After counting 466795 metaphases, 4288 chromosomal aberrations of various types were classified. The most frequent types of aberrations were acentrics and chromatid deletions. They made up 90% of the total number of aberrations. The remaining 10% were exchange aberrations. The number of chromosome exchanges (dicentrics and centric rings) was twice the number of chromatid exchanges. Overall, the portion ofcells with chromosomal or (and) chromatid aberrations was 0.89 +/- 0.01%; the frequency of acentrics was 0.29 +/- 0.01; the frequency of dicentrics was 0.046 +/- 0.003; the frequency of unstable chromosome aberrations was 0.35 +/- 0.01; and the frequency of chromatid aberrations was 0.57 +/- 0.01 per 100 cells.

[Hematopoiesis during remote period after acute radiation syndrome].

Based on the long (19.7 +/- 1.8 year) hemopoiesis follow-up study in 152 patients after acute radiation syndrome (ARS) as a result of exposure to gamma-, gamma-beta and gamma-eta radiation in a wide dose range (1.2-9.8 Gy) it was detected that cytopenia appears in the late consequences period: thrombocytopenia was found in 26.9% cases, leukocytopenia, neutropenia and lymphocytopenia--in 13.1% patients. A higher ARS degree causes the increase of various disorders (cytopenia and cytosis) in the late period. It reflects a tight interrelation between blood cell contents and radiation dose. Frequency of cytopenias increases if such somatic disorders: persistent hepatitis, hepatic cirrhosis and late radiation ulcers as appear.

[The results of 25 year-cytogenetic investigation of survivors exposed to different doses of irradiation in the Chernobyl accident].

Changes of registered levels of chromosome aberrations were studied in the peripheral blood lymphocyte cultures of 74 patients irradiated as a result of the Chernobyl accident by the instrumentality of the routine method during 25 year. The initial dose estimations by average dicentrics frequency varied from 0.2 to 9.8 Gy On the whole, the model of a double exponential type was the most adequate for the quantitative description of elimination of cytogenetical indices associated with different types of unstable chromosome aberrations. High individual variability of the elimination rate of chromosome aberrations and its dependency from the value of originally evaluated dose were discovered in the first period. The computer method of retrospective dose estimation was developed on the basis of this material. The method is based on the analysis of cell distributions in accordance with the number of dicentrics and as a whole, unstable chromosome aberrations, contained in them. In addition the dynamics of translocation frequencies in the peripheral blood lymphocyte cultures of a number of patients from this contingent was investigated starting from 10 years after irradiation by the instrumentality of FISH-method of chromosome staining.

[The dynamics of chromosomal aberration frequency in lymphocytes of the human peripheral blood after an acute irradiation].

Biodosimetrical estimation of radiation body burden is based on the counting of chromosomal aberration frequency in lymphocytes of the peripheral blood. This counting was made during a period of time after radiation. However, this frequency differs from counterpart, measured immediately after irradiation. This change caused by elimination of aberrant cells. In order to avoid consistent error in evaluation of dosage it is necessary to know the process generality of elimination temporally. The article contains the results of investigation of aberration frequency dynamics in lymphocytes of 41 patients' peripheral blood. The patients were observed in hospital after Chernobyl accident. The dosage of patients' irradiation varied in the range from 1.2 Gr to 9.8 Gr. Observations had been made during six years or so (from 61 to 2174 days). The results of these observations were used for the research of aberrant cells elimination rate. At the end of the analysis regularities of chromosomal aberration (dicentric and centrical rings) frequency change were obtained. The regularities comply with the exponential law of decreasing with the rate index of elimination (parameter b), which is equal (2.0 +/- 0.5) x 10(3) day(-1) in the range to 10(3) days after radiation. In some cases beyond this interval there was the change of the elimination rate. This fact should be researched additionally. The article contains a model for chromosomal aberration frequency dynamics expression. In analyzed range the b parameter can be constant, but for the extrapolation it in the area of less dosage it is essential to carry on additional investigations.

[Cytogenetical indices in remote times after acute irradiation of people. The computer method of retrospective dose estimation].

The computer method of retrospective dose estimation is used for the reconstruction of dose irradiation of victims in the result of Chernobyl accident by the results of repeated cytogenetical investigations in remote time after exposure. This method is based on the analysis of cell distributions in accordance with the number dicentrics and with unstable chromosome aberrations contained in them by special computer program. Received data demonstrate that for more exact reconstruction of original absorbed doses the need additional correction taking into account time after irradiation or frequencies of atypical chromosomes ensued from account of chromosome aberrations in remote time after exposure is needed.

[Elimination of chromosome aberrations in lymphocyte cultures of the peripheral blood in people at remote time after acute irradiation].

The changes in registered levels of chromosome aberrations are studied in the peripheral blood lymphocyte cultures of patients irradiated in result of Chernobyl accident. All 71 patients were examined with a different frequency for different survival patients. The initial evaluations of the doses for them by the average frequency of dicentrics were realized at the nearest terms after the irradiation (from 0.2 before 9.8 Gy for different patients). Repeated blood samples were collected during 6 years after the accident. On the whole the model of exponential type Y(T)/Y(0) = c + exp(b(0) + b(1)T), where Y(T)--the frequency dicentrics at the time of examinations; Y(0)--the originally discovered dicentric frequencies; T--the time past after irradiation (days) was the most adequate for the quantitative description of the elimination of cytogenetical indices associated with different types of unstable chromosome aberrations. Also as a result of this study high individual variability of the elimination rate of the chromosome aberrations and its dependence from the value of the originally evaluated dose were discovered.

[The comparison of molecular-biochemical and cytogenetic analyses of blood cells of patients long after the acute radiation sickness].

Molecular-biochemical and cytogenetic analyses were made on blood cells of 17 radiation accident victims who, from 1.7 to 43.8 years previously, had suffered acute radiation sickness (ARS) ranging from severity grades I to IV. Molecular-biochemical data were obtained with patients' leukocytes and with mononuclear cells on their oxidative status by a) the level of an anion-radical O2*- in the 3-(4,5-dimethyl-2-thiazol-2-yl)-2,5-diphenyl-2-tetrazolium bromide (MTT) test and b) the sum of reactive oxygen species in the 2,7-dichlorodihydrofluorescein diacetate (DCFDA) test together with a test for DNA strand unwinding in alkaline conditions by measurements of fluorescence intensity of ethidium bromide. Each parameter was measured in freshly sampled cells and during a 5-hour incubation as absolute means on 5 measurements and in % change from the initial values. Cytogenetic data were obtained from the standard metaphase preparations scored for routine unstable chromosomal aberrations (us-CA)--dicentrics; and stable aberrations (sCA)--translocations. The latter ones were assayed by the FISH method using whole chromosome 2, 4 and 12 fluorescent probes and scaled up to genome equivalence. For all patients reduced oxidative status of about 25-30% was obtained by the MTT-test (p < 0.005), and the DCFDA-test (p < 0.027). The yield of usCA depended on the time after irradiation with higher yields associated with the shorter postirradiation times and reducing almost to expected background frequencies. The yield of sCA was high for all patients, correlating with the severity of ARS whilst the molecular-biochemical parameters showed no relationship with ARS. A correlation was observed between parameters of oxidative status and % of cells with usCA: by the MTT-test r = from 0.50 up to 0.61 (p = from 0.06 up to 0.003), but by the DCFDA-test the strength of correlation was smaller: r = from 0.38 up to 0.48. An inverse correlation was found between initial oxidative state of mononuclear cells and the frequency of CA in lymphocytes. Similarly a marked inverse correlation between degree of DNA unwinding by the ethidium bromide assay on leukocytes and sCA in lymphocytes was also noted. The feasibility of radiation-induced delayed genomic instability in vivo for humans long time after irradiation is discussed.

[Comparative investigation of structural and gene somatic mutations in workers of nuclear chemical plants. II. Frequency of lymphocytes mutant in T-cell receptor loci].

Frequency of lymphocytes mutant at T-cell receptor (TCR) loci was defined in 42 workers of nuclear chemical plants. In 11 persons mainly exposed to external radiation the mean frequency of TCR-mutant lymphocytes was statistically significant by higher compared with control group of unexposed donors: 9.1 x 10(-4) vs 3.5 x 10(-4) correspondently (p < 0.01). Frequency of TCR-mutant lymphocytes did not correlate neither the frequency of structural mutations non doses of external exposure. In group of workers exposed to combined external and internal radiation (n = 31) the average frequency of TCR-mutant lymphocytes was higher compared with control level: 8.9 x 10(-4) vs 3.5 x 10(-4) correspondently (p < 0.01). Correlations between the frequency of TCR-mutant cells and Pu content in organism (r = 0.5; p = 0.005) and between the frequency of chromosome aberration of unstable and stable types (r = 0.5; p = 0.002 and r = 0.6; p = 0.036, correspondently) were set. Comparison of results of analysis of structural and gene mutations allows us to supose that in case of external exposure the observed disturbances can result from genome instability in remote period after irradiation. In case of combined exposure the genetic changes were possibly caused by the constant action of alpha-radiation from Pu containing in the body.

[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).

[The use of dicentric distribution in human peripheral blood lymphocytes for the retrospective estimation of the irradiation dosage]. / Ispol'zovanie raspredeleniia ditsentrikov v limfotsitakh perifericheskoi krovi cheloveka dlia retrospektivnoi otsenki dozy oblucheniia.

The paper presents the results of retrospective dose estimations in a number of Chernobyl victims by different approaches to the analysis of dicentric distribution in peripheral lymphocytes in blood samples taken a long time after the accident. Retrospective dose estimations are compared with dose estimates in the same individuals made immediately after the accident by dicentric frequencies.

[Determination of mutation frequency at loci of glycophorin A and T-cell receptors: informativeness for biological dosimetry of acute and prolonged irradiation]. / Opredelenie chastoty mutatsii po lokusam glikoforina A i T-kletochnogo retseptora: informativnost' dlia biologicheskoi dozimetrii ostrogo i prolongirovannogo oblucheniia.

The frequencies of somatic mutations at loci of glycophorin A (GPA) and T-cell receptor (TCR) were determined in persons exposed professionally to ionizing radiation or a result of accidents at nuclear power plants and in control donors. Dependence of glycophorin A mutant (NO) cell frequency on doses of acute (up to 3.5 Gy) and prolonged (up to 15.0 Gy) irradiation was shown. The slope of linear regression corresponded to increase of NO-mutant frequency by 31.1 x 10(-6)/Gy (r = 0.87, p < 0.0001) for acute irradiation and by 6.3 x 10(-6)/Gy (r = 0.61, p < 0.0001) for prolonged one. The 5-fold decrease of the linear regression slope in the case of prolonged irradiation makes significantly worse permissive ability of the GPA test. Therefore its use for biological dosimetry of prolonged irradiation is not expedient in dose interval up to 1 Gy. The frequency of mutations in genes of T-cell receptor significantly correlated with dose of irradiation only in group of donors with recent radiation exposure (r = 0.75, p = 0.0002). Meanwhile, the TCR method is more sensitive and informative for biological dosimetry of recent radiation, than the GPA test.

[Analysis of stable chromosome aberrations using G-banding stain in lymphocyte of patients with high dose radiation injury]. / Issledovanie stabil'nykh aberratsii khromosom metodom g-differentsial'nogo okrashivaniia v limfotsitakh krovi cheloveka posle oblucheniia v vysokoi doze.

The analysis was performed on 514 blood lymphocytes from a person accidentally exposed to 137Cs. Blood samples were collected 1 year after exposure three times at intervals of one month. Terminal deletions and simple translocations were found to predominate in all cases. No differences between these cases were observed on analysing total frequency of stable chromosome aberrations. However, the frequency of terminal deletions decreased and frequencies of exchange-type aberration increased with time after exposure. Chromosome #4 was more involved in stable aberrations than it would be expected from the relative chromosome lengths. Clonal aberrations del-ter (5)(q31 or 32) were found.

[Elimination of radiation-induced chromosomal damages in a human peripheral lymphocyte culture. I. The frequency of aberrations in the 1st and 2d mitoses]. / Eliminatsiia radiatsionno-indutsirovannykh povrezhdenii khromosom v kul'ture limfotsitov perifericheskoi krovi cheloveka. I. Chastota aberratsii v pervom i vtorom mitoze.

A comparative analysis of chromosome aberrations in the first and second division of cells in human peripheral blood lymphocyte cultures after gamma-irradiation in vitro at 1--5 Gy doses was performed. The lymphocytes of irradiated blood were incubated at 37 degrees with PHA and BrdU (20 micrograms/ml) for 58--66 hours. The first, second and third postirradiation division cells were identified by the sister chromatid differential staining technique. The percentage of cells in the first, second and third mitoses varied from 32 to 77, from 23 to 68 and from 0 to 9, respectively. Essential differences in frequency of aberrant cells and all chromosome-type aberrations between the first and second mitoses have been found at all irradiation doses. The frequency of paired fragments and dicentrics in the first division cells was on the average, respectively, 1.6 and 2 times higher than in the second division cells. In the first division cells almost all dicentrics were with associated paired fragments, in the second division cells the frequency of dicentrics without fragment amounted to 25--50%. At the range--doses of 2 to 5 Gy the distribution of dicentrics between cells in the first and second mitosis did not differ from the Poisson one.

[Frequency of chromosome aberrations induced in human peripheral lymphocytes by in vitro 60Co gamma quanta at doses of 1 to 5 Gr. in an analysis of the 1st-division cells at different fixation times]. / Chastota khromosomnykh aberratsii, indutsirovannykh v limfotsitakh perifericheskoi krovi cheloveka in vitro gamma-kvantami 60Co v dozakh 1--5 Gr, pri analize kletok pervogo deleniia v raznye sroki fiksatsii.

The quantitative analysis of chromosomal aberrations in the first division cells of 50-, 54-, 58-, 52- and 66-hour peripheral blood lymphocytes cultures of healthy donors was performed after irradiation in vitro with 60Co gamma-quantums at doses 1--5 Gy. Cells of the first division were identified by a differential staining of sister chromatid method using 5-bromdeoxyuridine. No significant differences in frequencies of aberrant cells and aberrations of chromosomal type were found between cultures fixed at different times. The distribution of dicentrics in cells did not differ from the Poisson distribution regardless of fixation times and doses. On the basis of these findings it is concluded that chromosomes of human peripheral blood lymphocytes passing the cell cycle at different rates have approximately equal radiosensitivity.

[Elimination of radiation-induced chromosome damage in a culture of human peripheral blood lymphocytes. II. The frequency of aberrations in the 1st to 5th postradiation mitoses]. / Eliminatsiia radiatsionno-indutsirovannykh povrezhdenii khromosom v kul'ture limfotsitov perifericheskoi krovi cheloveka. II. Chastota aberratsii v pervom--piatom postradiatsionnykh mitozakh.

The number of chromosome aberrations was estimated in the first-fifth mitoses in human peripheral blood lymphocytes cultured with PHA after gamma-irradiation in vitro with 1.5, 3 and 6 Gy doses. The lymphocytes of irradiated blood were incubated at 37 degrees with BrdU (20 micrograms/ml) for 62-122 hours. The first-fifth postirratiation mitoses were identified by the sister chromatid differential staining technique. At all the doses used with cells passing through the first and next postirradiation divisions, the decrease in the number of aberrant metaphases and all the aberration of chromosome type were observed, and with the increase in dose speed of their elimination was growing. No essential differences were found in frequency of paired fragments in the first-fourth mitoses after irradiation with 1.5 Gy dose, in the first-third mitoses after irradiation with 3 Gy dose or in the first-second mitoses after irradiation with 6 Gy dose. In lymphocyte cultures, exposed in 3 and 6 Gy doses, the number of dicentrics in the second mitosis was approximately 2 times smaller than in the first one, and in the third mitosis it was 2 times smaller than in the second one. In the first mitosis, almost all the dicentries were accompanied with paired fragments, in the second and third mitoses the shape of dicentrics without fragments was nearly 30-70%, and in the fourth-fifth mitoses it was almost 95-100%. The decrease in the number of atypical chromosomes, with cells passing through the first and next postirradiation mitoses, was noted only when lymphocytes irradiated with 6 Gy dose were analysed; with 1.5 and 3 Gy doses, the frequency of aberrations in the first-fifth and in the first-fourth mitoses was approximately equal.

[Use of the method of differential staining of sister chromatids for the study of cytogenetic radiation effects in human lymphocytes]. / Ispol'zovanie metodiki differentsial'nogo okrashivaniia sestrinskikh khromatid dlia izucheniia tsitogeneticheskikh éffektov oblucheniia v limfotsitakh cheloveka.

Chromosome aberrations in human peripheral blood lymphocytes cultivated with and without 5-bromodeoxyuridine (BDU) were studied and compared. In BDU cultures, chromosome aberrations were counted in the cells of the first postradiation mitosis. The rate of acentric aberrations and that of dicentrics + rings in these cultures were respectively lower and higher than in cultures without BDU. In BDU cultures, almost all the dicentrics had concomitant paired fragments, whereas in cultures without BDU, the rate of the dicentrics without fragments amounted to 0.3-6,2%. The distribution of the dicentrics among the cells in both the cultures obeyed the Poisson law. It is suggested that the differences cited are determined by the presence in the cultures without BDU of the cells of the 2d or subsequent mitoses. To support this suggestion, the authors studied chromosome aberrations in the 1st-4th postradiation mitoses. The cells of the 2d and 3d mitoses showed a high rate of acentric fragments. The number of the dicentrics was about twice as decreased after the cells experienced the 1st and each subsequent mitosis. In the first mitosis, all the dicentrics had concomitant paired fragments, whereas in the 2d-4th mitoses, the share of the dicentrics without fragments ranged from 18.7 to 95.5%. The advisability has been shown of using the differential staining of sister chromatids for identification of the cells of different generations in the culture, for raising the accuracy of counting the radiation-induced chromosome aberrations in human lymphocytes, and for studying the mechanisms of their elimination in the process of experiencing by the cells of the first and subsequent mitoses.

[Assessment of irradiation uniformity using the results of a cytogenetic study of human peripheral blood lymphocytes]. / Otsenka ravnomernosti oblucheniia po rezul'tatam tsitogeneticheskogo issledovaniia limfotsitov perifericheskoi krovi cheloveka.

A study was made of chromosome aberration during the I mitosis in PHA-stimulated lymphocytes from normal donors' peripheral blood following gamma-radiation in vitro in doses of 1 to 8 Gy. The dose-effect curves were plotted for different cytogenetic characteristics (the percentage of cells with dicentrics, dicentrics per 100 cells and aberrant cell). It is shown that during even or relatively even radiation, the doses calculated on the basis of the different cytological characteristics do not substantially differ and distribution of the dicentrics in the cells is governed by Poisson's law. During uneven radiation simulated by numeric experiments with formation of cell mixtures radiated in different doses, one could observe superdispersion of the cells with a different number of the dicentrics relative to Poisson's distribution, whereas the dose calculated according to the dicentrics (per 100 cells) was respectively higher and less than the doses calculated according to the number of the cells and dicentrics (per aberrant cell). A method for computerization of dicentric distribution in the cells to lymphocyte distribution according to the dose is described.

[Analysis of chromosome aberrations and prognosis of bone marrow syndrome severity in acute radiation injuries in man]. / Analiz aberratsii khromosom i prognozirovanie tiazhesti kostno-mozgovogo sindroma pri ostrykh radiatsionnykh porazheniiakh cheloveka.

Biological dose indication using chromosomal aberrations analysis is a reliable method of diagnosing acute radiation disease and prognosing bone marrow syndrome severity. Cytogenetic methods permit one not only to estimate the mean radiation dose in the subjects exposed that is most important in case of relatively uniform irradiation, but also to reveal the non-uniformity of radiation exposure. Estimation of aberrant cells in bone marrow puncture biopsy specimens obtained from different sites of the hemopoietic tissue and analysis of chromosomal aberrations in peripheral blood lymphocyte cultures can be used for this purpose. Materials including those obtained at the Chernobyl accident were analyzed with the use of the above methods, their advantages and shortcomings are considered, and equations of dose-response curves are presented.

[Case of chronic radiation sickness with subsequent leukemia in track driver subjected to long-external gamma-irradiation (cesium-137)]. / Sluchai khronicheskoi luchevoi bolezni s perekhodom v leikoz u voditelia gruzovika vsledstvie dlitel'nogo vneshnego gamma-oblusheniia.

The article deals with consequences seen in track driver after prolonged exposure to radiation caused by "lost" gamma-source (cesium-137) that long remained in receptacle of the vehicle's left door. Radiation dose averaged 8 Gy. The authors presented clinical manifestations, changes in peripheral blood and bone marrow, cytogenetic data by progression of radiation hemopoiesis hypoplasy to myelodysplastic syndrome and to acute leukaemia.