Search PubMed⌕ Search

Biomedical subjects

A N Chebotarev

Publications and source records attributed to A N Chebotarev.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Decrease of incidence of chromosome aberrations after a course of hyperbaric oxygenation].

The influence of the course of hyperbaric oxygenation (HBO) on the peripheral blood lymphocytes chromosomes of 7 patients with different pathology and of 3 healthy volunteers was studied. It is proved that after HBO course the frequency of chromosome, aberrations of chromatid type hasn't been practically changed whereas the frequency of aberrations of chromosome type significantly decreases by three times on the whole.

Cells, Cultured↗
PubMed1990

[Revision of th distribution of chromosome aberrations induced by chemical mutagens using the BUDR label].

Cell distribution was analysed with the help of the BrDU label for the number of chromosome aberrations and breaks induced by one-center (thiophosphamide and phosphamide) and two-center (dipine and fotrine) mutagens at the stage G0 in the Ist mitosis of human lymphocytes harvested at different times of culturing (from 56 to 96 h). The comparison was made between the type of aberration distribution in cells and the dependence of their frequency on the harvesting point for various mutagens. Poisson aberration distribution in cells for two-center mutagens was found to correspond to their constant frequency observed at different times of harvesting. On the other hand, for one-center mutagens, a geometrical distribution of chromosome breaks corresponded to an exponential decrease in their frequency in time. It is suggested that two-center chemical mutagens and ionizing radiation cause largely short-live damages which are realized into chromosome aberrations rather quickly (during one cell cycle). One-center mutagens, however, cause such damages that the probability of their transformation into chromosome aberrations is decreasing rather slowly in time, under the exponential law, and their realization into chromosome aberrations can occur in subsequent cell cycle.

Bromodeoxyuridine↗
PubMed1989

[Interchangeability of mutagens during fractionated effects of unequal concentrations of alkylating agents].

The ability of thiophosphamide and dipin to substitute for each other in "clastogenic adaptation" of human lymphocytes was investigated at Go phase. There were used 5 low concentrations of mutagens 2, 0.2, 2.10(-2), 2.10(-3), 2.10(-4) micrograms/ml and the high one of 20 micrograms/ml with which cells were treated 2 hr after the effect of low concentrations. The "protective" concentrations for both mutagens were 0.2, 2.10(-2), 2.10(-3) micrograms/ml. The pretreatment with thiophosphamide caused the decrease in chromatid aberrations in "challenge" treatment with dipin, the pretreatment with dipin caused the decrease in chromosome aberrations in "challenge" treatment with thiophosphamide.

Alkylating Agents↗
PubMed1989

[Effects of exposure time using preliminary concentrations on the mutagenic effect of the basic action of one-center and dual-center mutagens].

The effect of exposition with pretreatment for thiophosphamide and dipin of human lymphocytes at Go phase was investigated. There were used 5 low concentrations of mutagens: 2, 0, 2; 2.10(-2); 2.10(-3), 2.10(-4) mcg/ml with different exposure: 1/4 hr, 1/2 hr, 1 hr and 4 hr and high concentration of 20 mcg/ml by which cell have been treated. There was discovered the dependence of the "protective" concentration on the exposition: the increase of exposition of pretreatment induced the decrease of "protective" concentration and vice versa.

Alkylating Agents↗
PubMed1989

[Frequency of chromosome aberrations induced by mutagens of various functions in cells of the first division at various times of fixation].

The dynamics of chromosome aberrations in human lymphocyte culture cells of the 1-st division after exposure in the G0 phase for 1h to functionally different alkylating mutagens - ethyleneimine derivatives (bifunctional phosphamide, threefunctional thiophosphamide, tetrafunctional dipine and pentafunctional photrin) was analysed. The frequency of chromosome aberrations was constant after exposure to "dicentric" mutagens (dipine, photrin) at all times of fixation, while under the action of "monocentric" mutagens (phosphamide, thiophosphamide) this declined significantly with increasing the duration of cultivation. The portion of aberrations of the chromatid remains unaltered in time, in case of both "dicentric" and "monocentric" mutagens, reaching 75% for "monocentric" and 50% for "dicentric" of the total number of chromosome aberrations.

Chromosome Aberrations↗
PubMed1988

[Simultaneous estimation of sister chromatid exchange and evaluation of cell cycle delay].

The frequency of sister chromatid exchange and cell cycle duration were evaluated simultaneously. This approach is based on the analysis of distribution of cells with differential staining of sister chromatids after treatment of cells with 5-bromodeoxyuridine. The treatment of cells with thiotepa caused no changes in cell cycle duration, while the combination of thiotepa and hydroxyurea (HU) or cytosine-beta-D-arabinofuranoside (ARA-C) was observed to prolong cell cycle duration. Furthermore, it has been shown that caffeine, HU, ARA-C do not increase frequency of sister chromatid exchange in control cells and in cell treated with thiotepa.

Animals↗
PubMed1987

[Modeling of induction and elimination of sister chromatid exchanges in time].

Induction and elimination of sister chromatid exchanges (SCE) have been simulated during several cell cycles. Two models of SCE elimination are suggested. The first model postulates that the mutagen-induced lesions are not repaired, a lesion being only inherited by one daughter cell after DNA synthesis. According to the second model, lesions are completely repaired at the first S-phase. No SCE induction takes place during next cell cycles. SCE frequency ranges for both models are described by an equation, including the probability distribution function. The best correspondence in experimental and theoretical results was obtained using the model claiming repair of lesions during one cell cycle.

Animals↗
PubMed1986

[Mathematical model for estimating the ratio of cells having passed the different number of divisions in the culture].

Different versions of the stochastic expansion of the continuous determined linear model proposed formerly for evaluation of the ratio of cells having passed the different number of divisions in the culture were worked out and theoretically based. The influence of approximation precision of the continuous model by its discrete analogues on the adequacy of the process under study was examined. The problem of simultaneous identification of unknown parameters and the model's primary conditions was solved. The proposed methods for construction of the stochastic models for evaluation of the ratio of cells having passed the different number of divisions in the culture make it possible not only to determine analytically the correlation of metaphases of the first, second, third and following divisions at definite times of fixation and under different conditions, but also to evaluate reliability of the results obtained.

Cell Count↗
PubMed1984

Alterations in the baseline sister-chromatid exchange frequency in human lymphocyte culture following a number of cell divisions.

A significant decrease in the baseline of sister-chromatid exchanges (SCEs) was observed in cultured human lymphocytes, if 5-bromodeoxyuridine (BrdU) was added after 60 h of culture, and the cells were harvested at least 24-30 h after BrdU exposure. This decrease is supposed to occur if at least one cell division takes place before the addition of BrdU. For cytogenetic monitoring of mutagenic environmental factors, using human lymphocyte cultures, it is assumed that two time periods are sufficient for comparison.

Bromodeoxyuridine↗
PubMed1983

[Comparison of the frequencies of sister chromatid exchanges induced by thiophosphamide in vivo and in vitro].

The effects of thiophosphamide on rabbit lymphocytes were studied and compared in vivo and in vitro. In the course of in vitro action the dose was calculated by multiplying the thiophosphamide concentration by the time of in vitro treatment. In vivo the dose was calculated as integral of concentration variation function of thiophosphamide from the time of injection till the time of blood collection. It was demonstrated that as the dose was raised, the rate of sister chromatid exchanges increased linearly in vivo and in vitro. The coefficients of linear regressions were found to coincide. The data point to equal efficacy of thiophosphamide in vivo and in vitro.

Animals↗
PubMed1983

[Dynamics of the frequencies of chemically induced sister chromatid exchanges in a series of cell generations].

The number of sister chromatid exchanges (SCE) in a culture of human lymphocytes and the established cultures of Chinese hamster cells has been studied after the exposure to thiophosphamide and dipin at different stages of the cell cycle. The most pronounced effect is observed under the action of the mutagens at the G1 of the first cycle, prior to harvest. The SCE level becomes lower with the increase of the interval between the exposure to the mutagen and the time of 5-BUdR introduction. The number of SCEs per cell drops to the control level when the duration of the first interval is equal to that of the cell cycle. The results obtained prove the mutagen-induced impairments causing SCE formation to be repaired practically 100%, provided that at least one cycle of DNA replication took place.

Alkylating Agents↗
PubMed1983

[Comparison of the levels of chromosome aberration and sister chromatid exchange induced by chemical mutagens in vitro].

Dose dependencies of the induction of sister chromatid exchanges (SCEs) and chromosome aberrations were studied under in vivo exposure of mouse bone marrow cells to 5 alkylating agents. The efficacy of the induction of SCEs for all the substances was 20 to 60 times higher than that of the induction of chromosome aberrations. It was demonstrated that SCEs induced by chemical mutagens in vivo and in vitro are more sensitive tests than chromosome aberrations.

Aziridines↗
PubMed1983

[Correlation of the sister chromatid exchange level with chromosome aberrations induced by chemical mutagens in vivo].

The data on the dose dependencies of the induction of sister chromatid exchanges (SCE) and chromosomal aberrations during exposure of mouse bone marrow cells in vivo to 5 alkylating substances are provided. The efficacy of SCE induction was found to be higher than that of chromosomal aberrations. It was established that SCE induced by chemical mutagens in vivo and in vitro are more sensitive and stable tests than chromosomal aberrations.

Alkylating Agents↗