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Biomedical subjects

I M Beliakov

Publications and source records attributed to I M Beliakov.

13 recordsLinked to original sources
PubMedDate not supplied

[The effect of gamma irradiation on the direct intercellular interaction (rosette formation) of thymic macrophages with thymocytes].

In experiments with (CBA x C57BL/6)F1 mice, the effect of radiation on rosette formation between thymus macrophages (Th-MPh) and thymocytes (Thc) was studied on days 1, 4, 12, 30, and 60 following gamma irradiation with doses of 0.5, 2, 4, and 8 Gy. The influence of supernatants of thymus epithelial cells (EC) on the rosette formation was estimated. Gamma irradiation with doses of above 2 Gy was shown to cause a dose-dependent inhibition of rosette formation of Th-MPh with Thc in vitro. Recovery of rosette-forming ability of Th-MPh was observed on day 60 of the experiment. Two types of rosette-forming Th-MPh were identified: RFMPhII with low rate of binding to Thc and RFMPhII with high rate of binding to Thc. Radiation affects mainly the RFMPhII content. With radiation doses of 4 and 8 Gy no complete restoration of RFMPhI was observed on day 60. The total population of rosette-forming Th-MPh was restored on day 60 mainly due to cells with low rate of rosette formation. The EC supernatant promoted rosette formation of exposed Th-MPh with Thc. The effect was maximum at early times following irradiation of Th-MPh with a dose of 4 Gy.

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[Individual immunological parameters in clean-up team members and patients with sequelae of acute radiation sickness 5 years after the effects of the Chernobyl accident].

A study was made of deviations, beyond 1 sigma and 1.5 sigma of a mean value (M) of a donor group, in individual immunological parameters (for instance, the number of CD5+, CD2+, CD4+, CD8+, CD25+ and B-cells; alpha 1-thymosin concentration; and autoantibody titers to antigens of epithelial reticulum cell cytoplasm) in patients suffered acute radiation sickness (ARS) and liquidators of Chernobyl NPP accident. The radiation damage to the immune system was reliably detected in the affected subjects examined: they exhibited a decrease in the alpha 1-thymosin level below M = -1.5 sigma and in absolute B cellularity below M = -1 sigma; and increase in the number of CD25+ cells and in the level of serum autoantibodies to antigens of thymus epithelial reticulum cell cytoplasm. When several parameters selected were examined simultaneously the frequency of recording the deviations in merely one of them markedly increased.

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[Determination of autoantibodies to antigens of thymic epithelial cells of clean up team workers and patients who survived acute radiation sickness at distant periods after irradiation].

A group of patients, suffering from sequelae of acute radiation sickness (ARS), and liquidators was studied 5 years after exposure to a complex of factors resulting from the Chernobyl A.P.S. disaster. Studied were: the antibody titres to antigens of the cytoplasm of thymus epithelial reticulum cells and to Hassall's corpuscles the levels of serum immunoglobulins M, G, A; and the content of serum alpha 1-thymosin. Patients with ARS sequelae and liquidators showed a high level and incidence of autoantibodies to antigens of cytoplasm of thymus epithelial reticulum cells and to Hassall's corpuscles. There were no significant differences between the antibody levels in the blood of patients with ARS sequelae and liquidators. The antibodies were found to belong to IgM class; there was a correlation between the serum IgM titres and the rate of the indirect immunofluorescence reaction with autoantibodies to antigens of the cytoplasm of the thymus epithelial reticulum cells. To identify autoantibodies cryostat sections of human and mouse, (CBA x C57BL/6) F1, thymus as well as the epithelial and stromal cell culture of mouse thymus can equally be used.

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[Several indices of the peripheral immune system in clean up team workers and patients who survived acute radiation disease 5 years after effects of the radiation accident factors].

A group of liquidators and patients survived acute radiation sickness (ARS) was studied five years after the effect of radiation factors resulted from the Chernobyl A.P.S. disaster. Studied were the number of T-lymphocytes (SD2+, SD3+, SD5+), subpopulations SD16+ and SD25+, the content of SD16+ and SD25+ lymphocytes and B-cells, as well as the levels of serum IgM, A, G; determined was the concentration of serum alpha 1-thymosin. A decrease was noted in the number of T-cells of the examined patients, with respect to all markers studied: the number of SD4+ cells was found decreased in patients with ARS sequelae and normal in liquidators. The decrease in serum alpha 1-thymosin was a function of dose. Dynamics of changes in the T-cells of the examinees may reflect the new trends in the radiation response of T-lymphocytes which were not directly related to initial damages to the latter. The injury to the stroma of the thymus and especially to its epithelial cells may be the basis for later postirradiation damages to the immune system. The decrease in the concentration of alpha 1-thymosin in the blood serum of the examinee is the manifestation of the thymus hypofunction. In liquidators and patients with the ARS sequelae the number of SD25+ cells increased markedly indicating the existence of the source of endogenous cell activation. The content of B-lymphocytes in all studied groups of patients was reduced which may serve as a criterion of chronic stress.

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[Dynamics in changes of a1-thymosin level under irradiation of mice thymus in vivo and in vitro: relation to the antibody-antigen production of epithelial thymus reticulum].

In 3- and 9-month experiments with mice, a study was made of the effect of radiation on serum alpha 1-thymosine concentration after whole-body irradiation and local exposure of the thymus at doses of 1-20 Gy. The effect of 137Cs-gamma-rays on the in vitro cultured thymus stroma cells, with respect to alpha 1-thymosine secretion, and the influence of local irradiation of the thymus of production of autoantibodies that react with epithelial thymus cells were studied. Both whole-body irradiation and local exposure of the thymus were shown to cause changes in the alpha 1-thymosine content of the blood plasma. The direction and dynamics of the changes observed are different with whole-body and local exposure. Irradiation of cultured thymus cells of mice causes alterations in alpha 1-thymosine secretion, that is, stimulation at a dose of 1 Gy and inhibition at higher doses. With respect to dose- and time-response, these changes are closer to those observed in alpha 1-thymosine concentration in mouse serum after whole-body irradiation than after local exposure of the thymus in vivo. At remote times after local irradiation of the thymus with doses of 1-10 Gy, autoantibodies are found in mouse serum that react with epithelial cells of the thymus stroma. Autoantibodies are absent at doses of 15 and 20 Gy.

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PubMedDate not supplied

[The effect of gamma irradiation on the proliferative activity of the cambial epithelium in a culture of thymus stromal cells].

A study was made of the effect of gamma radiation on proliferation of thymus stroma epithelial cells (EC) of newborn mice (CBA x C57Bl/6)P1 where EC content varied from 55% to 85%. EC proliferation was assessed 24 and 48 h after gamma irradiation by studying the mitotic activity of thymus EC and rate of MTT recovery (which permitted us to determine the nature of proliferating cells by their morphology). The quantitative characteristics of the two methods were identical. The effect of gamma radiation was assessed at various cultivation times. Irradiation at the time of inoculation reduced the proliferation of cells to logarithmic phase of growth. Irradiation with doses of 10 and 20 Gy after two-day cultivation inhibited proliferation of thymus EC and with 15 Gy increased the proliferative activity of thymus epithelium.

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