[Molecular and cellular consequences of the Chernobyl accident].

In this paper the results of the Chernobyl accident investigation 5-10 and 24 years after are summarized. The genomic instability, adaptive response formation, genome damage and oxidative status have been investigated. The studies were performed on cells in culture, mice, children and adults living in contaminated areas and liquidators. On cells in culture after exposition in the accident zone and culturing thereafter in laboratory conditions the cell proliferative activity decrease; the late cell death, the frequency of cells with micronuclei and giant cells increasing have been observed. In the progeny of exposed cells the enhancement of radiosensitivity has been noticed. So we can suppose that in cultured cells exposition in the zone of the accident the genomic instability is induced which results in many disturbances. At the organism level in mice exposed in the Chernobyl zone the radiosensitivity increase and the decrease of endotheliocytes density in brain tissue has been observed. On the stimulated by PHA blood lymphocytes of children the increase of the frequency of cells with micronuclei more than 2 time have been noticed. In all groups investigated, the decrease of individuals with significant adaptive response was observed. In children and adults inhabitants the increase of radiosensitivity after low dose of irradiation has been noticed. 24-year after the accident it was discovered that in liquidators lymphocytes the frequency of cells with micronuclei, with chromosome type aberrations, with DNA double strand breaks have been increased; the reactive oxygen species (ROS) were decreased in comparison with the control population. We can suppose that genomic instability induced in residents of contaminated regions and liquidators long after the accident results in the genetic apparatus damage, radiosensitivity enhancement, hypoxia that represent risk factors and increase the probability of tumour and non-tumour diseases. The development of these pathological processes may happen in much more remote periods.

[Adaptive response in the different mitotic cycles after irradiation].

The frequency of cells with chromosome aberrations and the number of aberrations per cell by metaphase analysis have been studied in the nonirradiated progeny of irradiated human blood lymphocytes. The DNA fragmentation (DNA double strand breaks) have simultaneously been investigated by the DNA comet assay. PHA stimulated lymphocytes have been irradiated in the adaptive dose 0.05 Gy 24 h and in the challenge dose 1 Gy 48 h after stimulation to study the adaptive response (AR). 5-bromodeoxyuridine have been added for the identification the first--the fourth mitoses. It has been discovered that the frequency of chromosome aberrations is increased is all mitotic cycles after challenge irradiation, the level of double strand breaks is increased too. The adaptive response in induced by the adaptive and challenge irradiation in the first and the second mitotic cycles (fixation 48 and 72 h after stimulation) for the most parts of individuals, but it is absent in the third and the fourth mitosis. Only chromatid aberrations are observed in the first mitosis, but chromosome aberrations--in the following mitosis. Investigation by the DNA comet assay have showed the adaptive response is noticed 48-72 h after stimulation but it is insignificant 96 h. The conclusion is that the genomic instability is observed in nonirradiated progeny irradiated lymphocytes; the adaptive response is manifested up to third mitosis and is explained by the decreasing of the number of the chromatid and chromosome aberrations and DNA fragmentation. We can suppose that double strand DNA breaks can be signaling damage for the adaptive response induction.

[New approaches to diagnostics and identification of possible damages in normal humans under the conditions of microgravity and exposure to low doses of radiation].

The issues of radiation risk evaluation were addressed in the investigation of cytogenetic and molecular-biological changes in lymphocytes of cosmonauts and pilots of high-altitude airplanes. The goal was to determine individual sensitivity to the flight conditions and an additional factor (lymphocyte exposure to 1 Gy in situ), and adaptability as an index of induction of cell and organism resistance to extreme conditions.

[The adaptive response of first generation offsprings irradiated parents].

In offspring's of first generation irradiated inhabitants of Techa river (fathers, mothers and both parents) the spontaneous level of damaged blood lymphocytes, sensitivity of lymphocytes to the additional acute irradiation in dose 1.0 Gy and radioinduced adaptive response after adaptive (5 cGy) and challenge (1.0 Gy) irradiation 5 h after was studied. The micronuclei test with cytochalasin B as a criteria of the effect have been used. It was shown, that descendents of irradiated parents differ from the control group. The main difference is the significant decrease of the adaptive response frequency in the progeny. In the offspring's of the irradiated fathers and mothers there is no one individuals with the adaptive response; in the offspring's of both irradiated parents the frequency of individuals with adaptive response decreases in control from 19.5% to 6.8%. The distribution of descendents according to response on adaptive irradiation differ significantly from the control distribution and from the each other. And the tendency to the radiosensitivity increase after adaptive irradiation was observed. In the whole joint group of progeny the mean spontaneous cell frequency with micronuclei decreased, but the sensitivity of lymphocytes to the additional acute irradiation doesn't differ from the control. The results of the paper permit to suppose that transgenerational genome instability in human can be determined. Earlier discovered decrease of the adaptive response frequency in the Techa river livings is observed in the offspring's of irradiated fathers, mothers and both parents.

[Individual cytogenetic and molecular-biological characteristics of lymphocytes in blood of pilots and cosmonauts].

The purpose of this paper was the investigation of the pilots and of cosmonauts individual sensitivity to the fly conditions, to the additional irradiation (in the dose of 1 Gy), the adaptive response manifestation (in the doses 0.05 and 0.5 Gy). The DNA comet assay (the double strand DNA breaks was determined) and the method of unstable chromosome aberrations in metaphase was used. The human blood lymphocytes was the object of investigation. The significant individual differences were discovered in pilots and in cosmonauts in the initial DNA damage; in the sensitivity to the additional irradiation. The frequency of the adaptive response induction was decreased in the pilots in the comparison with the control group. The adaptive response was registered in cosmonauts (3 men). It is supposed that DNA damage, chromosome aberrations, sensitivity to the additional irradiation, the adaptive response manifestations can be used as biological markers of individual risk disease.

[On the response of a cell population to low-dose irradiation].

The cell composition of a population of human blood lymphocytes was studied after irradiation at doses of 5 cGy, 1.0 Gy and 5 cGy + 1.0 Gy and the use of a cytokinesis block. The frequencies of uni-, bi- and multinucleate lymphocytes with and without micronuclei (MN) were taken into account. By the standard criterion the frequency of binucleate lymphocytes with MN among binucleate lymphocytes--the donors were characterized as follows: in with reduction of radiosensitivity after irradiation with 5 cGy + 1.0 Gy as compared to the values of radiosensitivity after irradiation with 1.0 Gy only (an adaptive response, AR); in with no change of radiosensitivity after exposure to these doses (no AR); and with an increased ofradiosensitivity after exposure to these doses (syndrome of increased radiosensitivity, IRS). It was found that upon exposure to 1.0 Gy and 5 cGy + 1.0 Gy in some donors with AR, without AR and with IRS the total numbers of damaged cells in the population and the number of binucleate cells with MN were equal. This result calls in question the involvement of the repair mechanism in the alteration of radiosensitivity of lymphocytes in these donors. It was also observed that in the same donors a simultaneous increase (or a decrease in the case of IRS) of the portion of undamaged binucleate cells in the population took place. Our results demonstrate the existence of a new, populational, mechanism involved in the alteration of radiosensitivity after exposure to the adaptive and challenge doses.

[20 years after Chernobyl accident--is it a lot or not for the estimation its characteristics ?].

The results of long standing researches in the zones, which suffered from Chernobyl accident, on cultured cells, mice, blood lymphocytes of inhabitants of polluted regions (adults and children) are brought in the paper. The conclusion is that residence in polluted territories results in genomic instability, that is manifested in many effects on cytogenetic, cellular and organisms levels. It was shown, that in late descendants of cells after exposition in Chernobyl zone the increase of cell death, the micronuclei level, the frequency of giant cells, the enhancement of radiosensitivity and the absence of the adaptive response was observed. In the culture of embryonic fibroblasts, that was obtained from the exposed mice, the increase of cells with aberrations of chromosome and the frequency of multiaberrant cells was noticed. In mice exposed in Chernobyl zone the decrease of amounts of the endothelial cells in the different parts of the brain, the enhancement of mice radiosensitivity was observed. All effects were discovered in the late descendants of cells and can be the result of genomic instability induced by low level irradiation in polluted by Chernobyl accident regions.

[Effect of low dose irradiation on the reaction of blood lymphocytes of individuals with the somatic diseases].

The reaction of blood lymphocytes on adaptive irradiation in vitro (0.05 Gy) and challenge irradiation (1.0 Gy) 5 h after has been studied among 320 children 3-16 years old by micronuclei test with cytochalasin B cytokinetic block. The adaptive response or the hypersensitivity phenomenon (HS) has been determined by the calculation of the number of binucleated cells with micronuclei (MN) in 1000-2000 binucleated cells. For each individual by the chi2 criteria significant differences between the frequencies of damaged cells by irradiation in challenge dose and by combined action of adaptive and challenge doses have been detected. On the base of the results obtained the connection between AR or HS and the somatic diseases of different type and the disturbancies in systems of humoral and cell immunity has been studied. It was shown that in the row of allergic diseases and tuberculous infection among the significant part of the children (approximately 50%) the HS phenomenon was registered. The connection between the HS phenomenon and inflammatory processes (without allergic components), the logopedic disturbancies wasn't observed. It was shown in the group of HS children the deviation in the cell immunity system is registered. Significant deviations in HS group in the system of the humoral immunity is observed. So by the HS phenomenon significant number of the children have the somatic diseases and the deviation in the systems of cell and humoral immunity.

[Adaptive response of blood lymphocytes of the inhabitants of the South Ural chronically exposed to radiation]. / Adaptivnye sposobnosti limfotsitov krovi u zhitelei iuzhnogo urala, podvergshikhsia khronicheskomu oblucheniiu.

The inhabitants of Techa river villages exposed to injured radiation action and inhabitants of uncontaminated regions were examined by micronuclei (MN) assay. The initial damage of blood lymphocytes, the role of radiation in the induction of sensitivity to the acute irradiation and the ability to form the adaptive response were evaluated. It was shown that the initial level of damaged lymphocytes in the inhabitants of the contaminated area did not differ significantly from the spontaneous level. But in these people the sensitivity to acute irradiation was decreased. The ability to develop the adaptive response was decreased too. It was suggested that the radiation plays the main role in the development of radiosensitivity and adaptive response in chronically irradiated people.

[The cytogenetic damage, radiosensitivity and adaptive response in children living in the different districts of Moscow]. / Tsitogeneticheskie povrezhdeniia, radiochuvstvitel'nost' i adaptivnyi otvet u detei, prozhivaiushchikh v raznykh raionakh Moskvy.

The spontaneous level of blood lymphocytes with micronuclei (MN), the sensitivity to 1.0 Gy irradiation and adaptive response (AR) after adaptive irradiation with a dose of 0.05 Gy 5 hr later have been studied in children population living in different districts of Moscow. It was shown that spontaneous frequency of cells with MN, the sensitivity to 1.0 Gy acute irradiation and the AR manifestation have significant differences in samples taken from children living in different districts. The individual variability is significant also. In each group of children the individuals with the enhanced radiosensitivity after adaptive irradiation have been observed. In conformance with the data of radioecological inspection the radiation situation in different Moscow districts is quite safe on overage but in some districts the spontaneous level of lymphocytes with MN, and radiosensitivity after 0.05 Gy irradiation were enhanced, the AR was not found.

[Chromosome aberrations in human lymphocytes at a various duration of cultivation after irradiation]. / Aberratsii khromosom v limfotsitakh cheloveka pri razlichnoi prodolzhitel'nosti kul'tivirovaniia posle oblucheniia.

Human peripheral blood lymphocytes were exposed to 60Co gamma-rays (a dose of 3 Gy) and cultivated during seven days in the presence of PHA and BrdU. It was shown that the metaphases of the first and second mitosises occurred during cultivation of the irradiated and unirradiated lymphocytes, being evidence about of irregularity of the coming into division of various fractions of lymphocytes. The time of cultivation did not influence a rate of aberrations in metaphases of the first and second mitosises of the irradiated lymphocytes. During the first and the subsequent mitosises the number of exchange chromosome aberrations decreased and reached a control level in metaphases of the fourth and fifth mitosises. The number of paired fragments at second and third mitosises increased a little and started to decrease only in metaphases of the fourth and fifth mitosises. The decrease in chromosome aberrations with prolongation of the cultivation of lymphocytes after irradiating is a consequence of elimination of cells with chromosome damages during sequential mitotic divisions.

[On the new mechanism of adaptive response]. / O novom mekhanizme formirovaniia adaptivnogo otveta.

The role of changes in cell composition of population of human blood lymphocytes in the forming of an adaptive response (AR) has been studied. By micronuclei assay and cytokinetic block with cytohalasin B the frequency of mono-, bi- and multinuclear cells with micronuclei (MN) and without MN were determined in the initial population. The same parameters have been studied after exposure of the population to the adaptive (0.05 Gy), challenge (1.0 Gy) doses and to doses 0.05 + 1.0 Gy 5 hours after. 13 from 23 investigated individuals manifested the AR: the decreasing of the ratio of damaged binuclear cells to the all binuclear cells after the adaptive and challenge exposure. It was shown that the ways of an AR forming are different: in 7 of 13 individuals with AR the number of binuclear cells with MN did not decrease but the amount of binuclear undamaged cells increased. The ratio of these parameters enhances but not for the account of cells with MN decreasing. There is the linear correlation between the frequency of cells with MN and the frequency of binuclear cells in population (spontaneous, after irradiation with doses of 0.05, 1.0 and 0.05 + 1.0 Gy) with the coefficient of correlation about -1. These results show the presence of new mechanism of AR forming, which is not connect with the induction of damage repair and rather with the stimulation of cell division. In the another group of individuals the decrease in damaged cells number after irradiation with doses of 0.05 + 1.0 Gy have been observed. Probably the stimulation of repair system occurred to the moment of 1.0 Gy irradiation. Thus, the mechanism of an AR forming depends on the individual properties of organism. The work was suppoted by RFBR grant 03-04-48325a.

[The reaction of cell population to low level of irradiation]. / Reaktsiia populiatsii kletok na obluchenie v malykh dozakh.

The results of long-term investigations of the effectivity of low level irradiation (below 0.5 Gy) carried out on the cells in culture and blood human lymphocytes (adults and children) have been brought. In the experiments conducted in the laboratory conditions and in the contaminated with radionuclides regions (after Chernobyl accident) the genomic instability have been discovered. The cell manifestations of the genomic instability have been registered in the progeny of irradiated cells as the decreasing of proliferative activity, the increasing of the frequency of cells with micronuclei, the increasing of cells with sister chromatid exchanges, the late cell death, the absence of the adaptive response ability, the enhancement of the radiosensitivity. The results of the investigations of the adaptive response of blood lymphocytes have been presented. It was shown that in all populations investigated there are individuals without the adaptive response and the individuals with the enhancement of radiosensitivity after adaptive irradiation (0.05 Gy). On the basis of own results and the data of literature the possible mechanisms of low level irradiation effects are discussed. The conclusion is that: a. The population with new properties can be formed after low level irradiation; b. The effects and mechanisms of this effect realization can be different from that after irradiation with high doses.

[The cell composition in the lymphocyte population and the radiation adaptive response]. / Kletochnyi sostav populiatsii limfotsitov i radiatsionnyi adaptivnyi otvet.

Using lymphocytes of 5 healthy individuals the ability to adaptive response (AR), cell composition of population after PHA stimulation, changes in cell composition population after irradiation in the dose of 1.0 Gy and after irradiation in adaptive (0.05 Gy) and challenge (1.0 Gy) doses have been studied. AR observed in 2 of the 5 individuals only. After PHA stimulation the persons with AR have the total amount of cells after mitosis or during mitosis (the number of binucleated cells + the number of multinucleated cells + the whole cells with micronuclei + the number of mitotic cells) on average is higher than in persons without AR. In individuals with AR the linear correlation between the number of binucleated cells with micronuclei (on the 1000 scored binucleated cells) and the part of binucleated cells in the population is observed with coefficients of correlation -0.89 and -0.91. In the humans without AR this correlation is absent. The correlation observed permits to suppose that AR may occur at the expense of not only the decrease in number of damaged lymphocytes, but also the increase in the share of not damaged binucleated cell with the stable number of damaged cells.

[Cytogenetic results of irradiation of Southern Ural residents]. / Tsitogeneticheskie posledstviia oblucheniia zhitelei iuzhnogo Urala.

The paper summarizes the results of studies of 85 individuals exposed in the Southern Ural region. The spontaneous frequency of the cells with micronuclei (MN) in a population of human blood lymphocytes after PHA stimulation and cytokinetic block with cytochalasin B has been determined. The sensitivity of lymphocytes to the irradiation at the dose of 1.0 Gy and the adaptive response (AR) after the irradiation at the low adaptive dose of 0.05 Gy, and the challenge dose of 1.0 Gy 5 h later have been studied too. It was shown that the peculiarity of the Urals population consists in a higher individual variability of the frequency of cells with MN in all groups have been investigated (spontaneous, after acute irradiation in the dose 1.0 Gy) in comparison with Moscow people. The proportion of persons with a significant AR in the Urals groups was considerably lower than that identified among Moscow residents, and the number of persons with enhanced radiosensitivity increased following low-dose irradiation. We can suppose that prolonged action of low level radiation with another ecological factors, living in the contaminated regions result in the enhancement of the sensitivity to the genotoxic agents in the separate individuals.

[Level of spontaneous and radiation-induced cytogenetic damage in blood lymphocytes of children depending on age and life style]. / Uroven' spontannykh i indutsirovannykh oblucheniem tsitogeneticheskikh povrezhdenii v limfotsitakh krovi detei v zavisimosti ot vozrasta i uslovii zhizni.

On blood lymphocytes the frequency of cell with micronucleus was examined in different population of children. The groups with different lifestyle living in different ecological situation, and their reaction to the radiation exposure was investigated. It was shown that when the increased level of spontaneous cells with micronucleus was observed the increased radiosensitivity of the cells was found. The connection between the increased spontaneous level of the damaged cells with the enhanced sensitivity to irradiation in adaptive doses are discussed.

[Long-term effects of irradiation in the progeny of mammalian cells]. / Razvitie otdalennykh posledstvii v potomkakh obluchennykh kletok mlekopitaiushchikh.

It is shown that gamma-irradiation has remote consequences for mammalian cells cultivated in vitro. Many generations in the progeny of cells surviving acute and chronic irradiation at high and low doses are characterized by a number of abnormalities, including delayed cell death, the formation of micronuclei and giant cells, an increased frequency of sister chromatid exchanges, a reduced potential for repair, the loss of adaptive response, and increased radiosensitivity. These phenomena are regarded as manifestations of genomic instability induced by ionizing radiation.

[Increased radiosensitivity after irradiation of lymphocytes low adaptive doses]. / Fenomen povysheniia radiochuvstvutel'nosti posle oblucheniia limfotsitov v malykh adaptiruiushchikh dozakh.

The variability of blood lymphocyte reaction on the adaptive irradiation (0.05 Gy at first, then 1.0 Gy 5 h later) was investigated by micronuclei assay. Blood samples were obtained from 700 children. It was shown that in all groups studied there were children with enhanced radiosensitivity ("radiosensitivity syndrome"-RS) after exposure to adaptive low dose of radiation. The radiosensitivity syndrome occurred more often in groups of ill children; part of them was characterized by the enhanced blood content of immunoglobulin E, enhanced level of T helpers and T suppressors. A high spontaneous level of lymphocytes with micronucleus is a factor of radiosensitivity formation. The possible factors resulted in radiosensitivity syndrome are discussed.

[The use of sirdalud in cerebral palsy in children]. / Primenenie sirdaluda pri tserebral'nom paraliche u detei.

30 diplegic children (mean age 11.3 +/- 2.8 years old) with severe form of cerebral palsy received sirdalud monotherapy during 2-6 weeks (1 mg for children under 10 years old and 2 mg for older children, 3 times daily). Positive effects were determined in motor, autonomic and mental (emotional) spheres. Sirdalud was also very effective in patients after orthopedic-surgical treatment. Electroneuromyographic analysis showed the decrease of the synergic tonic activity, as well as the improvement of the supraspinal influences and the segmental interaction. Thus, the small doses of sirdalud are effective without side effects in children with cerebral palsy.

[Radiation-induced adaptive response in children and effect of external and internal factors]. / Radioindutsirovannyi adaptivnyi otvet u detei i vliianie na nego vneshnikh i vnutrennikh faktorov.

434 children 3-13 old age and 4 adult people 20-40 old age have been investigated by the use of micronucleus (MN) assay and cytokinetical block by cytochalasin B on the ability to the adaptive response (AR). The frequency of lymphocytes with MN was scored in 1000 binucleated cells after irradiation in challenge dose of 1 Gy and together in adaptive (0.05 Gy) and challenge doses. The significance of differences have been determined by chi 2 criteria. It was shown that definite AR was determined in approximately 20 percent of "normal" children, when in adult population--in approximately 50 percent cases. The part of children with AR decreases in the groups of children with defects of development, with mentally deficiencies, with hard heredity (the parents are the chronic alcoholics), with the high pressure of genotoxic agents. It was discovered that in about the half of the children there is opposite effect observed-irradiation in adaptive dose induce the increasing of radiosensitivity; this effect is insignificantly expressed in adult people. The problems of genetic determination of AR, influence of different factors, the significance of AR as the phenomen of protection from extremal action have been discussed.