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Biomedical subjects

V A Shevchenko

Publications and source records attributed to V A Shevchenko.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Analysis of chromosome aberrations on the basis of synaptonemal complexes in the offspring of mice irradiated with gamma-rays].

Electron-microscopic analysis of synaptonemal complexes (SC) spread on the surface of hypophase was carried out to study chromosome rearrangements in sterile and semisterile F1 offsprings of mice exposed to gamma-radiation at a dose of 5 Gy. Chromosome rearrangements were microscopically scored at diakinesis - metaphase I in the same animals. SC analysis at pachytene revealed chromosome rearrangements in 63% spermatocytes. Analysis of chromosomes at diakinesis - metaphase I in the same animals only revealed chromosome rearrangements in 32% cells. SC analysis permits detecting chromosome rearrangements undetectable at diakinesis - metaphase I.

Animals↗
PubMed1985

[Genetic effect of chronic gamma radiation exposure in male mice].

The frequency of reciprocal translocations (RT) in mouse spermatogonia induced by gamma-rays at doses of 1.5 to 4.5 Gy and dose rates of 2.7 X 10(-6), 5.8 X 10(-6), 9.4 X 10(-5) and 4.5 Gy/min was studied. A linear increase was observed in the RT frequency with increasing the dose, at all dose rates. At 9.4 X 10(-5) Gy/min the RT frequency was, on average, 10 times lower, as compared to that for a single acute dose rate of 4.5 Gy/min. Further reduction of the dose rate did not result in a decrease of the RT yield, and at the lowest dose rate of 2.7 X 10(-6) Gy/min (the dose being 3.0 Gy) the RT frequency was higher than using the same dose at dose rates of 5.8 X 10(-6) and 9.4 X 10(-5) Gy/min. Possible reasons for an increase in the RT frequency at low dose rates are considered. A study of the frequency of abnormal sperm heads (ASH) has shown that at the dose rate of 9.4 X 10(-5) Gy/min it is independent of an accumulated dose and is equal to the value obtained when exposing to an acute dose of 3.0 Gy. At dose rates of 2.7 X 10(-6) and 5.8 X 10(-6) Gy/min ASH frequencies were only slightly increased at all doses, as compared to the control level.

Animals↗
PubMed1985

[Teaching medical radiology to foreign students].

The paper is concerned with activities aimed at improvement of teaching medical radiology to foreign students. To overcome language difficulties and differences in the national secondary school educational systems, summary lectures with schemes are proposed enabling foreign students to rapidly orientate in the studied material during their independent work. Reference materials for foreign students contribute to the motivation of foreign students' cognition and drawing the teaching process near conditions of the students' future working activities.

Africa↗
PubMed1983

Genetic effects of radiocarbon in reproductive cells of male mice.

The genetic effect of incorporated radiocarbon was studied after single, long-term (33 days) and chronic (6 and 12 months) treatment of male mice (CBA X C57B1) F1 with [14C]glucose. The genetic effect in male germ cells was estimated by 3 tests: DLM frequency in post- and pre-meiotic cells, RT frequency in stem spermatogonia and frequency of abnormal sperm heads. Absorbed doses in the gonads were: 0.22, 0.50 and 1.01 Gy, after a single exposure; 0.74 and 1.47 Gy, after long-term exposures; and 0.006 and 0.031 Gy, after chronic exposure for 6 months; and 0.013 and 0.066 Gy, for 12 months. The results suggest that DLM frequency in post-meiotic cells increased linearly with increasing the dose of 14C single and long-term exposures at a dose of 1.47 Gy only. A chronic treatment with [14C]glucose induced no increase in DLM frequency. RT frequency in stem spermatogonia was statistically significantly higher than the control level after the single and long-term exposure to 14C. A comparison of the results with the results of external single and chronic gamma-irradiation allows the conclusion that the relative genetic efficiency of radiocarbon as compared with that of gamma-rays is about 1.

Animals↗
PubMed1983

[Age-related characteristics of the normal blood content of lipids and lipoproteins and in arterial hypertension].

The quantity of low and very low density lipoproteins and the total cholesterine is increased in the blood of healthy subjects with advanced age (60-74) as compared with young subjects (20-30). The incidence of hyperlipoproteinemias is increased and cholesterine content is reduced in the composition of high density lipoproteins. In old age (75-89) those discrepancies are less manifested as compared with the young. Hyperlipoproteinemias (IIa, IIb, II and IV types) are more frequent in hypertonic disease, mainly in young patients and patients with advanced age. The content of lipids and lipoproteins in blood is increased in atherosclerotic systolic hypertension; hyperlipoproteinemias (mainly IV type) are found more often in old age.

Adult↗
PubMed1978

[Genetic effects of induced in populations by the radioactive nuclear fission products of 235U. II. Prognostication of the genetic effectiveness of irradiation at low dose rates].

Experiments have been carried out on Chlorella, beans, wheat and developing loach eggs to study the dose-response relationship (dose-function of dose rate) with 90Sr, 90Y and 147Pm as the sources of beta-radiation. The yield of point mutations in Chlorella under 147Pm and that of chromosome aberrations in cells of bean roof and apical meristem tissue as well as in meiosis of wheat and bean cells irradiated by 90Sr- 90Y is proved to show degree dependence at a dose less than 1. It means that the dose which doubles the number of induced mutations is not constant and depends on the dose rate. Reverse relationship is shown between dose intensity and genetic effect per dose unit. The decrease in the yield of genetic damages in the range of dose rates analysed is supposed to be due to repair activation induced by ionizing radiations. In view of these results, consideration is given to the role of the level of spontaneous mutagenesis in estimation of the resolution of test systems. An increase in the level of the spontaneous mutational process is shown to increase the size of population samples which are ment, when analysed, to reveal statistically significant differences between the effect observed and the level of spontaneous mutagenesis. The possibility of application of the experimental results to the prediction of effects of ionizing radiations on natural animal and plant populations is considered.

Animals↗
PubMed1975

The effect of ionizing radiations with different LET on survival and mutation in Chlorella.

The exposure of cells of Chlorella vulgaris LARG-I to radiations with a low LET (consisting of gamma-rays) yielded sigmoid dose-effect curves, whereas the action of radiations with a high LET (multiply charged ions of carbon C12(+6), boron B11(+2), neon Ne22(+4), argon Ar40(+8)) gave exponential curves. The rate of visible mutations depends directly on dose in the case of radiations with a low LET; it is a maximum after the action of radiations with a high LET. The highest RBE is shown by multiply charged ions of carbon (dE/dX 2850 MeV g-1 cm2). With dE/dX higher and lower than that of carbon ions the biological efficiency of radiations is less.

Argon↗
PubMedDate not supplied

Genetic effect of chronic exposure of male mice to gamma-rays.

The frequency of reciprocal translocations (RT) in mouse spermatogonia induced by gamma-rays at doses of 1.5-4.5 Gy and dose rates of 2.7 X 10(-6), 5.8 X 10(-6), 9.4 X 10(-5) and 4.5 Gy/min was studied. At all dose rates there was a linear increase in the RT frequency with increasing dose. At a dose rate of 9.4 X 10(-5) Gy/min, the RT frequency was on average 10 times lower than that for a single acute dose rate of 4.5 Gy/min. Further dose rate reduction did not result in a decrease in the RT yield, and at the lowest dose rate of 2.7 X 10(-6) Gy/min and a dose of 3.0 Gy the RT frequency was higher than at dose rates of 5.8 X 10(-6) and 9.4 X 10(-5) Gy/min and the same dose. Possible reasons for an increase in the RT frequency at low dose rates are considered. A study of the frequency of occurrence of abnormal sperm heads (ASH) has shown that a dose rate of 9.4 X 10(-5) Gy/min, this frequency is independent of an accumulated dose and is the same as that at an acute dose of 3.0 Gy. At dose rates of 2.7 X 10(-6) and 5.8 X 10(-6) Gy/min, ASH frequencies were only slightly increased at all doses compared to the control level.

Animals↗
PubMedDate not supplied

[Genetic effects in populations of plants growing in the zone of Kyshtym and Chernobyl accidents].

Studies to analyze the genetic processes in natural populations of plants were started on the territory of the East-Ural Radioactive Trace (EURT) in 1962 and in the zone of the Chernobyl accident in May 1986. The main directions of the genetic studies in both radioactive areas were similar: 1) study of the mutation process intensity depending on the dose and dose rate and analysis of dose-effect relationships for different genetic changes (point mutations, chromosome aberrations in mitosis and meiosis) in irradiated plant populations; 2) study of the mutation process dynamics in generations of chronically (prolongly) irradiated populations of plants; 3) analysis of microevolutionary processes in irradiated plant populations. The report presents an analysis of observed dose-effect relationships under the action of radiation on populations of Arabidopsis thaliana, Pinus sylvestris and a number of other plant species. Analysis of the mutation processes dynamics in 8 Arabidopsis populations growing in the zone of the Chernobyl catastrophe has demonstrated that the level of the embryo lethal mutations 10 years after the accident in the irradiated populations significantly exceeds the control level. The following phenomena observed in chronically irradiated populations have also been considered: increased radioresistance of irradiated populations (radioadaptation), the appearance of abnormal karyotypes and selective markers upon chronic irradiation. The authors call attention to the high importance of monitoring of genetic processes in irradiated plant populations for understanding of the action of radiation on human populations.

Genes, Lethal↗
PubMedDate not supplied

[The effect of mutagenic environmental factors on recombination in Drosophila melanogaster].

We studied recombination in Drosophila melanogaster males exposed in a thermoelectric power station in Moscow for six years and, for comparison, in another thermoelectric power station during 1994. The frequency of recombination in the experimental males was two to three times that in the control. The annual differences in the frequency of recombination in the experimental males were not statistically significant. The differences between the data obtained for two different thermoelectric power stations were not statistically significant as well. A marked increase in the frequency of recombination in the D. melanogaster males exposed at thermoelectric power stations may be considered as an adequate reaction to the presence of a sufficient amount of effective mutagens in discharges of thermoelectric power stations.

Air Pollutants↗
PubMedDate not supplied

[Alteration of polymorphic systems of Centaurea scabiosa L. under chronic irradiation].

Isoenzyme and morphological polymorphism alteration in populations of perennial grass Centaurea scabiosa L. (scaly cornflower) has been studied. These populations exist on the territory of East Ural Radioactive Trace more than 40 years and are chronically exposed to beta-irradiation. Directional shift of allele frequencies on the loci Per1, Pgi2, Sod1, Lap has been detected. The fact of accumulating genetic load by chronically irradiated populations has been demonstrated. Possible reasons of discovered alterations are discussed. The analysis of the obtained data shows that the irradiated populations have greater similarity with one another than with a control, but relation between genetic distances and accumulated doses hasn't been revealed. The hypothesis is that an extra factor--gene flow from a "clean" territory influences the genetic structure of irradiated populations.

Asteraceae↗
PubMedDate not supplied

[Cytotoxic and cytogenetic effects of radiation are modulated by introduction of RNA preparations obtained from various body tissues].

We studied the influence of various gamma-ray doses on the death pattern of Wistar rats and the changes in lethality after introduction of RNA isolated from various tissues in the organism. All studied RNA introduced into the irradiated animals proved to clearly stimulate repair of the cells damaged by radiation and to decrease both cytotoxic and cytogenetic effects of gamma-rays. The most pronounced effect on the cells was specific for RNA isolated from the matching tissue.

Animals↗