[Induction of DNA damage in blood leucocytes and of cytogenetic injuries in bone marrow polychromatic erythrocytes in mice exposed to low-LET and high-LET radiation and in their progeny].

The present work was aimed at studying the molecular and cellular levels of the response of the hematopoietic system in mice and their progeny to the action of low-LET and high-LET radiation at different times after exposure. The damage to the genome at the molecular level was assessed by the comet assay in peripheral blood leucocytes, whereas at the cellular level it was estimated by means of the micronuclear test in the marrow cells, after exposure of mice to X-radiation of 1, 3 and 5 Gy and to a high-LET low-intensity radiation at thedoses of 0.14 and 0.35 Gy, as well as to a combined effect of these types of radiation. When accessing the level of the DNA damage to individual cells by the comet assay, we also used, apart from a commonly accepted parameter %TDNA, additional characteristics: the proportions of leucocytes with an intact and highly fragmented DNA. Using these parameters, we detected the changes characterizing the dynamics of the leukocyte population in mouse blood at different times after the action of X-ray and high-LET radiation. It was found that: (1) the DNA damage increases with the dose of high-LET radiation; (2) the level of damage in the progeny of the animals exposed to high-LET radiation does not differ from that in unirradiated animals both at the molecular and cytogenetic levels; and (3) a decrease in the radiosensitivity of the progeny of the mice exposed to high-LET radiation at a dose of 0.35 Gy makes itself evident only at the molecular level, which may point to the possible transgeneration transmission of genomic lesions.

[Influence of low-dose-rate red and near-infrared radiations on the level of reactive oxygen species, the genetic apparatus and the tumor growth in mice in vivo].

The effect of low-dose-rate red and near-infrared radiations from the matrix of light emitted diode (650 nm and 850 nm) and a He-Ne laser (633 nm) on activation of the reserve of a natural defense system in the mice exposed to radiation in vivo was studied by the level of reactive oxygen species (ROS) production in blood cells, the induction of cytogenetic adaptive response in bone marrow cells, thymus and spleen, and the rate of Ehrlich ascites carcinoma growth in a solid form. As a positive control animals were irradiated with X-rays by the scheme of the radiation-induced adaptive response (0.1 Gy + 1.5 Gy). The levels of ROS production was assessed in whole blood by luminol-dependent chemiluminescence, of cytogenetic damage--by the "micronucleus test" in the bone marrow, the weight of the thymus and spleen--by index of organ, and the rate of tumor growth--according to its size for 30 days after inoculation. Adaptogenic and anticarcinogenic effects of studied radiations were revealed. The values of these effects were not different from those in animals pre-irradiated with the X-rays. The relationship between the level of ROS production and adaptive response induction in the mice under the influence of non-ionizing radiation was first ascertained. The experimental data obtained may indicate a similar mechanism of induction of protective responses to ionizing and non-ionizing radiations in mice in vivo.

Effect of infrared and X-ray radiation on thymus cells and the rate of growth of Ehrlich carcinoma.

We studied the effect of infrared light with a wavelength of 850 nm and modulated frequency of 101 Hz and X-ray radiation on the induction of cross-adaptive and radiation responses in the thymus and on the rate of tumor growth in mice in vivo. Preliminary exposure to infrared and X-ray radiation was shown to result in recovery in thymus weight after irradiation in a dose of 1.5 Gy and also inhibited the growth rate of Ehrlich carcinoma. These data attest to common mechanisms of the adaptive response induced by infrared and X-ray radiation in mice. Infrared light can be used as an adaptogen to adapt the animals to adverse factors.

[The effect of infrared and X-ray radiation on the production of reactive oxygen species in blood and induction of cytogenetic damage in the bone marrow of mice in vivo].

The goal of the present work was to study the effect of infrared light (IRL) at a wavelength of 850 nm modulated by a frequency of 101 Hz with a mode of power 22 mW/cm2 and X-rays with a voltage of 200 kV at a dose rate of 1 Gy/min on the production of reactive oxygen species (ROS) in blood cells using luminol-dependent chemiluminescence, as well as on the induction of a cytogenetic damage in bone marrow cells of mice by the in vivo micronucleus test. The experiments performed have shown: 1) the level of the ROS production in blood of the mice exposed to IRL and X-rays at an adapting dose of 0.1 Gy reaches the peak value after 0.5 h and drops to the ROS level in untreated animals 5 h after either exposure; 2) irradiation of mice with IRL and X-rays at a dose of 0.1 Gy induces adaptive responses both in blood cells and bone marrow cells of mice. These adaptive responses were revealed only 5 h after both exposures, when the level of ROS production decreased to the ROS level in untreated animals; they are equal in magnitude and dynamics and persist up to 2 months.

101 Hz frequency-modulated infrared light induces cytogenetic adaptive response in mouse bone marrow in vivo.

The micronucleus test was used tu study the possibility of inducing cross-adaptive response in mouse bone marrow cells in vivo with an 850 nm infrared light modulated by a 101 Hz frequency, emitted by a light therapy device "Kurator". We demonstrated that this exposure led to a substantial reduction of cytogenetic cell damage produced by further exposure of animals to X-radiation in the dose of 1.5 Gy, i.e. it induced an adaptive response which did not differ by the magnitude and time course from the adaptive response to radiation.

[Peculiar effects of low doses of high let radiation on mice].

Experiments with exposure of mice to low doses of chronic high-LET radiation were carried out in the radiation field behind the concrete wall of the Serpukhov accelerators of protons with the energy of 70 GeV. The goal was to study dose dependence, radiation adaptive response (AR), and genetic instability. Mice (SHK strain) were irradiated continuously 15, 24 and 31 days which corresponded to the doses of 11.5, 21.5 and 31.5 Gy. Cytogenetic damages were determined using the micronuclear test in marrow polychromatophil erythrocytes. It was shown that all the experimental doses aggravated the cytogenetic damage; however, no AR induction in marrow cells was observed. Males of the F1 generation born from the males irradiated at 11.5 Gy had same level of spontaneous cytogenetic damage as males born from non-irradiated parents. Yet, they displayed an exaggerated sensitivity to additional exposure to 1.5 Gy and no AR induction by the standard gamma-protocol which is indicative of genetic instability.

[The effect of low-dose rate radiation simulating the high-altitude flight conditions on mice in vivo].

In present work, we investigated the peculiarities of the effect of a low-dose rate high-LET radiation that simulates the spectral and component composition of the radiation field formed in the atmosphere at a height of 10 km on mice in vivo. The dose dependence and adaptive response were examined. Irradiation of mice was performed for 24 h a day in the radiation field behind the concrete shield of the Serpukhov accelerator of 70 GeV protons for the time (15-31 days) necessary to accumulate the required doses. The experiments demonstrated that irradiation of mice in vivo in the dose range of 11.5-31.5 cGy leads to an increase in cytogenetic damage to bone marrow cells and induces no adaptive response in bone marrow cells.

Special differentiation requirements of original and enriched secondary cytotoxic T lymphocyte precursors (pCTL-2 memory cell) specific for the class I histocompatibility molecule.

The in vivo-induced pCTL-2 cells of the L3T4- Lyt-2+ phenotype specific for the H-2Kb molecule are converted into effector CTLs in mixed lymphocyte culture (MLC) in the presence of heat-treated donor stimulators much more efficiently when the donor and recipient differ from each other, not only in the major histocompatibility complex (MHC) class I (H-2Kb) (anti-B10.MBR B10.AKM) but also in the MHC classes I + II, i.e., Kb + Ib (anti-C57BL/6 B10.D2 (R101)). The differentiation of original pCTL-2 is enhanced as the result of a synergistic action of the Kb alloantigen and rIL-2 in small doses. The anti-Kb pCTL-2, after their separation from helper T cells non-adherent to the macrophage donor monolayer and their subsequent elution from it, give rise to pronounced differentiation in simplified conditions over 3 days in monoculture in the absence of both stimulators and rIL-2. It is suggested that spontaneous and highly efficient specific differentiation of the eluted pCTL-2 is due to a dramatically enhanced secretion of the CTL differentiation factor by pCTL-2 themselves, and in addition, rIL-2 can also contribute to the secretion of this factor.

Action of chronic irradiation on the cytogenetic damage of human lymphocyte culture.

The action of chronic irradiation (dose rate 2.9 Gy/day) on human lymphocyte culture was investigated. Whole blood was irradiated at 37 degrees C. Aliquots (0.2 ml) of whole blood were cultivated by the standard method. A medium containing phytohemagglutinin was added immediately after irradiation. All structural chromosome- and chromatid-type changes were recorded. The experimental data showed that the conditions of irradiation of lymphocytes affected neither the background level of chromosome damage nor their radiosensitivity. The obtained dose-response curve of chromosome aberrations was described by a linear regression, which then became a plateau. There is no statistically significant difference between the results for the low doses (10-50 cGy) of chronic and acute radiation.

[Effect of chronic irradiation on cytogenetic mammalian cell injuries in culture]. / Vliianie khronicheskogo oblucheniia na tsitogeneticheskoe porazhenie kletok mlekopitaiushchikh v kulture.

The action of chronical irradiation on Chinese hamster fibroblasts and human peripheral blood lymphocytes was studied. The similar character of dose response for both types of cells and the absence of dose-rate effects at low doses were shown.

[Induction of cytogenetic damages by combined action of heavy metal salts, chronic and acute gamma irradiation in bone marrow cells of mice and rats]. / Kombinirovannoe deistvie solei tiazhelykh metallov, khronicheskogo i ostrogo gamma-oblucheniia na velichinu tsitogeneticheskogo povrezhdeniia v kletkakh kostnogo mozga myshei i krys.

The aim of the present work was to study the combined action of salts of heavy metals (lead and cadmium), and acute and chronic gamma-irradiation on the cytogenetic damage to bone marrow cells of rats and mice. It was shown that the chronic exposure of rats and mice in vivo to gamma-irradiation induced the adaptive response. The salts of heavy metals supplemented to the diet of rats enhanced the cytogenetic damage to the non-irradiated animals, slightly enhanced the effect of chronic and acute gamma-irradiation, decreased the cytogenetic adaptive response induced by chronic gamma-irradiation.

[Detection of genomic instability in offspring of male mice chronically exposed to gamma-radiation by the "adaptive response" test]. / Vyiavlenie s pomoshch'iu testa "adaptivnyi otvet" nestabil'nosti genoma u potomstva samtsov myshei, podvergnutykh khronicheskomu vozdeistviiu gamma-izlucheniia.

The genomic instability (GI) in somatic cells of the progeny (F1 generation) of male mice chronically exposed to low-dose gamma-radiation was studied by comparative analysis of chromosome damage. BALB/C male mice exposed to 0.1 Gy (0.01 Gy/day) and 0.5 Gy (0.01 and 0.05 Gy/day) were mated with unirradiated females 15 days after irradiation. For comparison of radiosensitivity, two-month-old males, the descendants of irradiated and unirradiated animals, were subjected to irradiation with a dose of 1.5 Gy (0.47 Gy/min) from a 60Co source. GI was revealed by the standard scheme of adaptive response. The experiments indicated that, by using the test "adaptive response", it is possible to detect the transition of gamma-radiation-induced genomic instability in sex cells of male parent into somatic cells of mice (F1 generation) either from changes in radiosensitivity or by the absence of the adaptive response induced by a standard scheme.

[Low doses of radiation decrease the level of spontaneous and gamma-induced chromosomal mutagenesis in bone marrow cells of mice in vivo]. / Malye dozy radiatsii snizhaiut uroven' spontannogo i gamma-indutsirovannogo khromosomnogo mutageneza v kletkakh kostnogo mozga myshei in vivo.

Low doses of ionizing radiation are known to induce adaptive response (AR), which is characterized in most cases by temporary nature, though the possibility of long-term persistence of AR is not ruled out. In this investigation we studied the effect of low doses of gamma-radiation on both high-dose radiation-induced and spontaneous level of cytogenetic damage throughout the life of mice. SHK male mice 2 months old were used. Priming doses of 0.1 and 0.2 Gy (0.125 Gy/min, gamma-radiation from 60Co) were used. A challenging dose of 1.5 Gy (1 Gy/min) was used in the experiments using a routine AR experimental design. The frequency of micronucleated polychromatic erythrocytes in bone marrow cells of primed, primed and challenged, and control groups was assessed at various times of animal life span. It was shown that: a) single low-dose gamma-irradiation induces a cytogenetic AR which can be revealed at 1, 3, 6, 9, 12 months after priming; b) single low-dose gamma-irradiation decreases the cytogenetic damage to a level below the spontaneous rate at the end of lifetime (20 months) of animals; c) ability to induce adaptive response does not depend on the age of animals at the moment of priming irradiation. In conclusion, the mechanisms underlying AR not only protect from chromosome damage induced by high-dose irradiation but also may play a role in spontaneous mutagenesis during aging of animals.

[Dependence of the cytogenetic adaptive response in the rat bone marrow cells on the dose of chronic gamma irradiation in vivo]. / Zavisimost' velichiny tsitogeneticheskogo adaptivnogo otveta v kletkakh kostnogo mozga krys ot dozy khronicheskogo gamma-oblucheniia in vivo.

The induction of chromosome aberrations in bone marrow cells of rats exposed to chronic gamma-irradiation and subsequently to acute gamma-irradiation was studied. Adult male rats were exposed ot 3-40 cGy (2.9 cGy/day) of chronic gamma-irradiation (adaptive dose) and subsequently to 4 or 6 Gy of gamma-rays (47 cGy/min, challenge dose). The yield of chromosome aberrations in marrow cells induced by adaptive and challenge dose was lower than the sum of the yields separately induced by chronic and acute gamma-irradiation. The most effective dose for induction of the adaptive response was 0.4 Gy.

[Estimation of genetic effects of chronic exposure to low-dose rate gamma-radiation by cytogenetic methods and DNA-comet assay]. / Otsenka geneticheskikh éffektov khronicheskogo vozdeistviia nizkointensivnogo gamma-izlucheniia tsitogeneticheskimi metodami i metodom DNK-komet.

The study of genetic effects in CBA/lac mice exposed for 1 year to constant low dose-rate gamma-radiation at a dose-rate 63 cGy/year has been carried out. We have shown the significant increase in the DNA breaks' level in spleen lymphocytes by comet-assay beginning from the total absorbed dose of 20 cGy. It is possible that the DNA breaks' level increase resulted from the structural rearrangement of chromatin or induction of lymphocyte proliferation. The results obtained by micronucleus test have proved that the mutagenic effect of chronic low dose-rate gamma-radiation depends on cell type and respectively on cell proliferation rate, cell differentiation, etc. So, by the end of experiment the significant increase in the frequency of PCE with micronuclei (MN) was observed. However, in contrast, the frequency of NCE with MN was not increased. No significant increase in the percent of lung cells with MN was registered.

[Action of low doses of gamma-radiation on cytogenetic damage in polychromatophilic erythrocytes of bone marrow in mice in vivo]. / Deistvie malykh doz gamma-radiatsii na tsitogeneticheskoe povrezhdenie v polikhromatofil'nykh éritrotsitakh kostnogo mozga myshei in vivo.

The frequency of micronuclei was estimated in bone marrow polychromatic erythrocytes (PCEs) of mice gamma-irradiated in vivo at doses of 5-50 cGy. The dose-effect curve was found to have a complex stepwise pattern with three consequent segments: (1) high radiosensitivity, (2) a significant decrease in radiosensitivity, and (3) an increase in radiosensitivity.

[Induction of cytogenetic damage to rat bone marrow cells by combined exposure to chronic and acute gamma radiation]. / Induktsiia tsitogeneticheskogo povrezhdenniia v kletkakh kostnogo mozga krys pri kombinirovannom vozdeistvii khronicheskogo i ostrogo gamma-oblucheniia.

The combined influence of various doses of chronic irradiation (0.029 Gy/day) followed by acute irradiation at doses of 4 and 6 Gy (0.47 Gy/min) on the frequency of chromosomal aberrations in rat bone-marrow cells was studied. A pronounced adaptive response was observed at all doses of chronic irradiation followed by acute irradiation.

[Induction of cytogenetic damage in Chinese hamster cells after combined exposure to low doses of gamma-radiation and various chemical and physical agents]. / Induktsiia tsitogeneticheskogo povrezhdeniia v kletkakh kitaiskogo khomiachka pri kombinirovannom vozdeistvii malykh doz gamma-radiatsii i razlichnykh khimicheskikh i fizicheskikh agentov.

Supersensitivity of Chinese hamster cells to low doses of gamma-radiation (dose range 5 to 50 cGy) was revealed by means of the cytokinesis-block micronucleus test. Treating these cells with caffeine (repair inhibitor) and mercaptoethylamine (radioprotector) and exposing them to secondary radiation emitted by protons with an energy of 70 GeV showed that this supersensitivity is associated with the absence of cytogenetic repair. When cells at the G2 phase received preliminary doses of 30 and 75 cGy before being irradiated at 150 cGy, the incidence of cytogenetic damage decreased, i.e., an adaptive cell response resulting from a radiation-induced mitotic delay was observed.

[Correlation between the duration of radiation adaptive response in bone marrow cells of mice and the dose of gamma-irradiation in vivo]. / Zavisimost' dlitel'nogo sokhraneniia radiatsionnogo adaptivnogo otveta v kletkakh kostnogo mozga myshei ot dozy gamma-oblucheniia in vivo.

The dependence between the adaptive response and adaptive dose was studied on the basis of cytogenetic damage in polychromatic erythrocytes of bone marrow cells in mice after a low dose gamma-irradiation in vivo. The adaptive response to doses of 0.1 and 0.2 Gy was found to be retained for at least two months after irradiation. However, the adaptive dose of 0.4 Gy did not induce prolonged adaptive response.

[Extracts of regenerating Planarians regulate proliferation of vertebrate cells]. / Ekstrakty regeneriruiushchikh planarii reguliruiut proliferatsiiu kletok pozvonochnykh.

The effects of extracts from intact and regenerating planarians on cell behaviour in culture were studied. The extracts were added to the culture of Chinese hamster fibroblasts and to the primary culture of human lymphocytes. Some extracts contained active agents which influenced the proliferation of fibroblasts increasing or decreasing the mitotic index. The extracts exerted no effect on the mitotic index of lymphocytes. When the extracts were added to the lymphocyte culture together with phytohemagglutinin, which induces the proliferation, the mitotic index somewhat increased. The extracts of regenerating planarians contain factors which activate and inhibit cell proliferation in culture. The active factors stimulated, rather than induced proliferation.