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Biomedical subjects

G A Klevezal'

Publications and source records attributed to G A Klevezal'.

10 recordsLinked to original sources
PubMed1994

[Cumulative radiation dosage and epidemiological research in the Chernobyl region].

Individual biological dosimetry covering chromosomal analysis and electronic paramagnetic resonance spectrometry has been performed in 1300 subjects exposed to ionizing radiation after the Chernobyl accident. Cumulative radiation doses above 40 ImC were registered in 5%, about 100 ImC in 1% of the examinees. In 1% of cytogenetic investigations there appeared multiaberrant cells indicative of hot particle incorporation. Regional epidemiologists do not record changes in the incidence of hematological diseases. This may be explained by a small percent of the dose carriers, rare occurrence of hematological disorders and the time of radiation-induced oncogenic effects. The above representative group exposed to definite radiation doses may serve the subject of epidemiological surveys on the role of low-dose and low-rate radiation in pathogenesis of human diseases.

Chromosome Aberrations↗
PubMed1990

[Determining the accumulated dose of gamma radiation in the tooth enamel].

Following ideas of Japanese and Canadian scientists the authors tried to develop practical application of dental enamel for dosimetry of gamma-radiation accumulated by an individual. Human teeth were irradiated in vitro with gamma-rays of 60Co and with x-rays, and the amount of free radicals in ++non-caries enamel was measured on an ESR spectrometer. Linear regression ESR signals on dose of radiation within an interval of 0.1-20 Gy were plotted for gamma- and x-rays with regression coefficients 0.276 and 0.693, respectively. These regressions were used for estimation of accumulated doses of gamma-radiation in 85 residents of Byelorussia and 301 residents of the Tomsk region during investigation of teeth that were removed in normal dental practice.

Adult↗
PubMed1981

[Diurnal layer formation in the incisor dentin of rodents].

The growth of dentin of the constantly growing lower incisors in rodents was studied using tetracycline as a vital marker of the growing parts of bones and teeth. In the common vole in nature the incisors grow in length at a rate of 490 micrometers per day; a basal-apical gradient of growth of the tooth walls in thickness was found: the minimal daily increment at the tooth base and the maximal in the apical third, it decreases again at the very apex. In the peripulp part of dentin of the apical incisor half there are diurnal layers seen both on polished sections and stained slides the formation of which correlates with the diurnal rhythm of skeleton growth. The diurnal dentin layers form in the apical incisor half only. The odontoblasts appear to begin to function rhythmically from the middle of their life on only. A similar phenomenon was found in a natural population of large-toothed redbacked voles. The topography of dentin layers in the laboratory rats is similar to that in the voles but the layers are not distinct and the basal-apical gradient of dentin growth is observed in young animals, rather than in the old ones.

Animals↗
PubMedDate not supplied

[New prospects in assessing the absorbed radiation dose by electron paramagnetic resonance].

Spin-lattice relaxation rates of radiation induced and background centers in dental enamel have been investigated by electron spin resonance techniques. It has been found that these centers differ in the value of the saturation half-power and the saturation process. Based on these experimental results a new approach to discrimination of the radiation induced signal from the total ESR spectrum of dental enamel is proposed. Comparison of the current methods of radiation dose estimation by the ESR analysis has been performed using the new approach.

Dental Enamel↗
PubMedDate not supplied

[The dynamics of the radiation load on reindeer on Novaya Zemlya].

The ESR analysis was carried out aiming at studying the activity of radionuclides in the dental enamel, dentin, and mandible bone tissues of reindeer of Novaya Zemlya. Doses of absorbed ionizing radiation were assessed. It was determined that the doses obtained by reindeer during underground nuclear tests were ten times higher and the activity of 90Sr was greater than those for reindeer living after the nuclear tests were suspended. Relatively high values of doses were observed for reindeer living before the nuclear weapons were invented. This fact is accounted for by an elevated level of natural radiation in the region.

Animals↗