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Biomedical subjects

V G Skvortsov

Publications and source records attributed to V G Skvortsov.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

ESR and TL dosimetry systems: comparative measurements for human phantom.

Mixtures of small fragments of tooth enamel as well as thermoluminescence (TL) dosimeters were placed into the tissue-equivalent phantom of the human head with skeleton (approximately at the level of the jaws) and irradiated using 137Cs low dose-rate gamma therapeutic sources ('SELEKTRON' LDR 137Cs). Phantom, samples of teeth and TL detectors were irradiated behind water tank to produce scattered irradiation. The same irradiation with the same geometry was performed in air too. For gamma-spectrometry 137Cs sources with very low activity were used but with the same geometry as therapeutic sources. The absorbed dose in enamel was estimated with the help of ESR spectrometer 'ESP-300 E' (Brucker). The samples of tooth enamel were partially used for preliminary dose evaluation by ESR signal before starting of experiment. TL dosimetry was performed by TL reader model 8800 (HARSHAW) using TL dosimeters calibrated with 137Cs. The paper presents data obtained in comparative aspects.

Cesium Radioisotopes↗
PubMedDate not supplied

[NO-inhibiting activity of radioprotectors].

The effect of radioprotectors of different structure on the syntheses of nitric oxide induced by endotoxin in mice was studied. Using ESR-spectroscopy and spin trap techniques, it was shown that compounds of different chemical structure, such as aminothiols, isothiuronium derivatives, thiazolines, indolylalkylamines and others, suppressed the nitric oxide production in a whole body. The analysis of the relevant literature has confirmed the phenomenon described by the authors: radioprotectors show NO-inhibiting activity.

Animals↗
PubMedDate not supplied

[Retrospective dose estimation in remote period after exposure using different biological methods].

Investigation of application of chromosome aberrations of lymphocytes in peripheral blood for biological dosimetry purposes in remote (up to 40 years) period after acute exposure to doses of 1 Gy and more was carried out. The comparative analysis of frequency of unstable and stable (using FISH and G-banding methods) aberrations was performed for 24 subjects accidentally exposed to radiation on nuclear submarines during 1961-1985. Statistically significant increasing of frequency of dicentrics and centric rings was determined in the exposed subjects in remote period after exposure to compare with controls. Their sum frequency in the exposed group varied depending on ARS heaviness from 0.1 to 1.0 aberrations per 100 cells. In control group it was from 0 to 0.2 correspondingly. Translocation frequency (complete + incomplete) fixed by FISH method (2, 4, and 12 chromosomes) varied within the limits of 0.2-16.0 for exposed subjects and 0.3-1.26 translocations per genome per 100 cells for controls. Some examined persons (5 subjects) exposed to accident in 1985 had results of analysis of unstable chromosome aberration in acute period after exposure that allow to estimate obtained doses by dicentrics frequency which having good correlation with ARS heaviness. Individual dosed using traslocation frequency were defined retrospectively in 11 from 21 exposed persons. They correlate with calculated physics doses and doses estimated by haematolotical parameters in acute period and also doses obtained by ESR spectroscopy of tooth enamel in remote period.

Chromosome Aberrations↗
PubMedDate not supplied

[Theoretical analysis of the effect of the photoreactivation of E. coli cells irradiated with gamma quanta].

The assumption that the formation of pyrimidine dimers in E. coli cells, placed in a transient aqueous medium exposed to gamma-quanta, is conditioned by Cerenkov radiation laid the basis for the development of a biophysical model to explain the photoreactivation effect observed. The dependence of the effect upon gamma-radiation energy and the volume of the exposed suspension is predicted and compared with experimental data.

Biophysical Phenomena↗
PubMedDate not supplied

[The oxygen effect in E. coli cells. Role of the photoreactivated component in modifying the oxygen effect in E. coli WP2 uvrA6 cells].

A study was made of a contribution of photoreactivated lesions to the oxygen effect (OE) manifestation in cells of UV-sensitive E. coli WP2 uvrA6. It was shown that the contribution of the photoreactivated lesions depends upon radiation energy and gas conditions in which radiation is delivered. The OE value in the uvrA6-mutant may be modified in the irradiation conditions preventing induction of the photoreactivated lesions (gamma-irradiation in the presence of nigrosine, and X-irradiation).

Aniline Compounds↗
PubMedDate not supplied

[Combined effect of photoreactivation and temperature on the survival of cells from E. coli B, irradiated with short-wave UV light].

A study was made of the survival curves of E. coli B(fil+/lon-) exposed to far UV-light (lambda = 254 nm) plated immediately after liquid holding recovery and after photoreactivation and incubated overnight at 37 degrees and 42 degrees. It was shown that the survival rate was always higher at 42 degrees C irrespective of the modification technique applied. Since the temperature-induced modification was significant after complete elimination of pyrimidine dimers (PD) a conclusion was made that UV-light, in addition to PD, induced just one more type of damages modified by temperature.

DNA Repair↗