It was found that the development of the pathobiochemical syndrome under the effect of low radiation doses on the animal body was effectively prevented by a concurrent application of CoA biosynthetic precursor and carnithine. The mechanism governing the protective effect of the complex involved a membrane-stabilizing action and normalization of the intracellular thiol disulfide status of the coenzymes (glutathione, coenzyme A).
The antiradical and antioxidative activities of ursodeoxycholic acid were demonstrated for the first time, and the mechanism of action based on the capacity of this compound to bind superoxide anion was disclosed.
In inhibiting by calcium cyanamide the dehydrogenase pathway of acetaldehyde utilization, a new mechanism of homeostatic control of animal liver endogenous ethanol level was found which combined peroxidase activity of catalase with reductase activity of alcohol dehydrogenase.
The effects of ultraviolet and laser irradiation on the functional activities of thiamine-dependent enzymes (thiamine triphosphatase and alcohol oxidase, 2-oxoglutarate dehydrogenase complex) were studied. It was shown that the activatory and inhibitory effects of coherent irradiation were due to the complex structure of the protein molecules and depended on the dose, wavelength and density of irradiation energy. The supramolecular protein complexes were most susceptible to the laser modifying effect, which was manifested in changing the conformational states of their constituent enzymes and alterating the rates of the association-dissociation changes in them.
It was established that experimental hypothyroidism in animals was accompanied by disturbances in the functional activity of the hypophysis and adrenal system with a pronounced decrease of the blood adrenal corticosterone levels and the activity of steroid-inducing tyrosine aminotransferase accompanied by considerably increased concentrations of stable aldehyde products of lipid peroxidation in thyroid gland tissue.
Subdiaphragmatic vagotomy and injection of glutamic acid to the caudal solitary tract nucleus was shown to diminish endotoxin-induced changes in temperature and pain sensitivity. In experiments on anterior hypothalamic slices, wide distribution of inhibitory synaptic connections realized via GABAb-receptors was shown. An enhanced electrical activity in the solitary tract nucleus and vagal afferent fibers was found, and changes in the microcirculation of the heart, gastrocnemius muscles and autonomicganglia were revealed during experimental fever.
The involvement of nitric oxide in increasing activity of sensory fibers of mesenteric nerves during prolonged (up to 2 h) ischemia of a small intestine segment was shown. The process of fistula formation in ileocolopexy was studied, which is essentially important for surgical practice. The increased activity of nerve elements in the vascular wall was found during ileocolopexy, and especially in its combination with pyrogenic influences.
It is established that a short-term ultraviolet radiation of blood via a light catheter implanted to the vein, performed in the first phase of experimental fever, reduces the development of its second phase. Exposure to low-intensity electromagnetic fields considerably disturbed the processes of aerobic supply in the brain and liver and led to an increase in II-oxycorticosteroidss in blood and an appreciable change in the state of the immune system.
In experimental model of neuroencephalopathy obtained by 6-week treatment of adult rats with ammonium sulfate, a tendency was found towards a decrease in the concentration of nerve growth factor in the liver, heart, kidneys, and skeletal muscles and its increase in brain tissues.
A new concept of establishing life maintenance systems after large radiation accidents was proposed. With a view to this, regional norms of natural radiation background in different countries and in Belarus were quantitatively evaluated since without this knowledge it is impossible to correctly assess dose exposures of the population in contaminated areas.
It is concluded that the acute external irradiation in low doses and the 137Cs incorporation lead to the disturbances in reproductive function of organism. These disturbances manifest in the change of reception of estrogens in uterus and androgens in testes, change of morphofunctional state of spermatogenic epithelium cells and nucleic acids content in testes of animals. These changes remain for a long period, especially at the 137Cs incorporation and combined irradiation.
It is shown that the single external irradiation, 137Cs incorporation, their combined influence on adult organism cause changes in the structure of bone marrow cell organization. These changes manifest in the disturbance in ratio of cells in different blood-forming shoots, the widening of range of chromosomal aberrations (chromatid and chromosome exchanges) which have been found not only in the nearest but also in the remote terms of observation, especially in female rats. The delay in differentiation of cell co-operations in various zones of adrenal gland was found in new-born animals which had been irradiated with 137Cs during their intrauterine period. This leads to the development of atypical forms of its cortical and marrow substance, the disturbance of their functional establishing.
The notions of the role of endothelium in mechanisms of radiation-induced disturbances of regulation of vessels function have been grounded. The relaxing action of endothelium becomes stronger after the acute g-irradiation. The prolonged g-irradiation causes the decrease of endothelium-mediated dilatation reactions of arterial vessels.
It has been revealed at the investigation of sorption properties of soil that the leading mechanism of 137Cs interaction in primary period is the ionic exchange with soil organic substance. The absorption of radiocesium by soil increases with the increase of humus content. The interaction of radionuclide with mineral components begins to prevail at longer (more than 30 days) contact of 137Cs with soil. The mineral part plays the principal role in 90Sr absorption in soddy-podzolic soils with few humus. However, with the increase of organic substance share the humus substances begin to prevail in absorbing radiostrontium.
As a result of investigations in marginal zone of bog on the territory of South Palesse, the difference was found between the distributions of micro- and macroelements in soil of landscape-geochemical profile. This was estimated as presence of geochemical barrier. The concentration of macroelements (Na, K, Si, etc.) in soil of barrier is several times as low as that in soil of conjugated landscape plots whereas the microelements (V, Ni, Cu, etc.) are accumulated in soil of barrier. The results of calculations of the coefficient of 137Cs transfer into plants show that it changes by the landscape-geochemical profile analogously to the microelements concentration, i.e. increases on the plot of geochemical barrier.
In herbaceous plants growing in zone of high radioactive pollution the increased frequency of chromosomal aberrations is observed at the bloom phase as well as the rise of peroxidase activity in leaves. It leads to the decreased fertilizing ability of pollen, weak morphological completeness of raceme and, as a result, decrease of seed germination. The combined analysis of these indices can become the criterion of prognosis of development of phytocoenoses on radiocontaminated ecotopes.
Source: "Main Results of Fundamental Research. 1996--1997". Eds. F.A.Lakhvich and N.N.Kostyukovich. National Academy of Sciences of Belarus, Minsk, 1998.
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