[Antioxidative defense and structural changes in the brain of rats with experimental diabetes mellitus].

The state of enzymatic and non-enzymatic components of the antioxidative defense system (ADS) and lipid peroxidation was studied in the homogenates of the brain of rats with diabetes melhtus (DM) on days 30, 60, and 90 after administration of alloxan. There was a decrease in the buffer capacity of ADS: reductions in the activities of superoxide dismutase (on DM days 60 and 90), glutathione peroxidase and antiradical activity (on day 90) and glutathione reductase (in all periods of DM). This was followed by the progressive enhancement of lipid peroxidation processes, achieving the maximum magnitude on day 90 of DM (as estimated by the level of malonic dialdehyde). Concurrent brain tissue ultrastructural analysis revealed slightly pronounced oxidative lesions of all cell elements, which enhanced by day 90 of DM. The most marked changes were found in the neuroglial cells, in astrocytes in particular, as compared with cerebral microvascular neurons and endotheliocytes. Administration of the a-lipoic acid agent espa-lipon to rats with DM produced a significant positive effect on the state of the ADS components, promoted the elimination of active manifestations of abnormal processes in the neuroglial cells and neurons and the development of compensatory and reducing processes.

[Increase of probability of cell loss in the endothelium of blood vessel capillaries in progeny of rats after a low-dose irradiation of one of the parents (electron microscopy study)]. / Povyshenie veroiatnosti gibeli kletok v éndotelii krovenosnykh kapilliarov u potomkov krys posle oblucheniia odnogo iz roditelei v malykh dozakh (élektronno-mikroskopicheskoe issledovanie).

The total gamma-irradiation of Wistar rats at a dose of 0.25 Gy as well as at higher doses (0.5, 2 and 4.5 Gy) produces in the capillary endothelial cells of myocardium and lung a pronounced, dose-independent increase of the yield of necrotized cells. Similar changes were revealed in the animals, of which one of the parents (a male one day, a female seven days prior to copulation) was irradiated at doses of 0.25 and 0.5 Gy. This effect was observed in all studied descendants. The massive induction of the changes already by low radiation actions and their dose-independence allow considering the revealed effects as a manifestation of peculiar cellular reactions that presumably have epigenetic nature.

[Atypical transformation of cell populations after low irradiation and other actions]. / Neobychnaia transformatsiia kletochnykh populiatsii posle slabykh radiatsionnykh i nekotorykh drugikh vozdeistvii.

Ionizing irradiation at low doses and some weak non-irradiational (including non-mutagenic) actions can produce a peculiar cell reaction, such as a massive, dose-independent transition to a new regime of existence. The changes appear saltationally. They are maintained for a very long time by both rarely and actively dividing cells. The most characteristic phenotype of the studied transformation is a stable increase of probability of cell damage and death. Some other manifestations of this transformation have been also revealed. This unusual response is found upon observation of totally different biological objects (unicellular organisms, cells of various mammalian tissues) to be regarded as a general biological regularity. The role of such radiational alterations in pathogenesis of remote consequences of low-dose irradiation is discussed.

[Specific long-term cellular changes under effects of low doses of radiation]. / Osobye dolgovremennye izmeneniia kletok pri vozdeistvii radiatsii v malykh dozakh.

We examined the peculiar form of a tissue postirradiative reaction characterizing by massive, dose-independent transition of cell populations to the steady state modification with the essential raise of cell damage and cell loss probability as compared with the probability level of the same alterations in controls. We described some other signs of such type of cellular transformation. It was found that the indicated cellular condition occurred both in active and slowly proliferating tissues. The reaction occurred at relatively low doses of irradiation. Some nonmutagenic factors also may evoke such effects. Our experimental data allow us to suppose the epigenetic mechanizms taking part in the induction and preservation of such alterations. The discovered form of cellular reaction manifestating in different biological objects may be considered as some general biological tendency. The importance of the studied reaction in the pathogenesis of late consequences of low dose irradiation is discussed.

[External signals can induce stable increase in frequency of cell death in populations]. / Vneshnie signaly mogut indutsirovat' ustoichivoe povyshenie chastoty gibeli kletok v populiatsiiakh.

Relatively weak radiation and some other external actions, producing no "forced" cell death, trigger some intracellular mechanisms in various unicellular organisms (amoebae, ciliates, yeasts) and in the studied mammalian cells (rat vascular endotheliocytes). These mechanisms provide spasmodic changes: massive transition of cell populations into a stationary alternative state which is characterized by an increased predisposition to cell death, in comparison with the initial level. This phenomenon is considered as a particular, widely spread in nature form of genetic control of cell death frequency populations.

[Pseudomutagenesis. The persistent increase in the level of cellular variability induced by radiation and some other agents]. / K probleme psevdomutageneza. Persistiruiushchee povyshenie urovnia izmenchivosti kletok, indutsiruemoe radiatsiei i nekotorymi drugimi agentami.

Electron microscopic investigation of capillary endothelium cells in myocardium of irradiated rats revealed an unusual effect of persistent increase of probability of cell damage, similar in many relations to that described earlier for various unicellular species. New effect, unlike those traditionally studied, is characterised by non-stochastic nature, large number of the involved cells, reveals itself even after faint influences, and can be induced as well by agents other than radiation. The question is put on the probable commonness between these changes and the pseudomutagenesis which has the similar phenomenology.

[Effect of radiologic contrast chemoembolization on ultrastructural changes of malignant liver neoplasms]. / Ultrastrukturnye izmeneniia zlokachestvannykh opukholei pecheni poslemaslianoi rentgenokontrastnoi khimioémbolizatsii.

The authors confirm the efficacy of treating primary and metastatic cancer of the liver by selective blocking of vessels in the involved liver part with an oily x-ray contrast agent with a citostatic dioxadet. Profound irreversible injury to tumor tissue was observed. Only solitary tumor cells were left slightly injured. Excepting a narrow adjacent area, lesser amount of lipid tissue accumulated in the tumor; hepatocytes were sufficiently well preserved, showing signs of reparation and increased functional activity 1-2 weeks after chemoembolization.

[Comparative study of the changes in structural parameters of collagen fibers during natural aging and pneumosclerosis formation]. / Sravnitel'noe izuchenie izmenenii strukturnykh parametrov kollagenovykh volokon pri estestvennom starenii i formirovanii pnevmoskleroza.

Changes in diameter of the collagen fibers and their number in fascicles of the rat lung in the process of natural ageing and formation of radiation-induced pneumo-sclerosis were studied electron microscopically. The decrease of the fibril thickness and the increase of their number in fascicles progressed during the postirradiation period and reached the values absent in the control animals.

[The modifying effect of a hypoxic gas mixture on the development of radiation-induced sclerosis]. / Modifizierende Wirkung hypoxischer Gasgemische auf die Enwicklung von strahleninduzierten Sklerosen.

Female mice (CBA X C57 Bl) F1 were exposed a single total-body gamma-irradiation with a dose efficiency of 6.5 Gy/min with doses of 2.5-7.5 Gy in air or inhaling a gas mixture of 6-6.5% oxygen and 94-93% nitrogen. All naturally died animals were examined pathoanatomically. By means of the rate of cardio- and nephroscleroses a protective effect of hypoxia was found with a dose modification factor of 1.5. Dynamics and degree of intensity of a radiogenic pneumosclerosis were studied by means of a stereologic analysis 3, 6, and 12 months after a single roentgen irradiation of the right thorax half of rats with a dose efficiency of 2.2 Gy/min with doses of 10, 14.3, 20 Gy in air and 14.3 and 20 Gy inhaling a gas mixture with 10% oxygen and 90% nitrogen. Applying the criterion of accumulation of connective tissue within the irradiated lung the protecting effect of hypoxia was estimated according to the dose modification coefficient, that varied in a range of 1.0-1.64.

[Electron microscopic analysis of postradiation apoptotic death of thymocytes and peripheral blood lymphocytes]. / Elektronno-mikroskopicheskii analiz postradiatsionnoi apoptoticheskoi gibeli timotsitov i limfotsitov perifericheskoi krovi.

Some stages of the apoptotic death of lymphoid cells (thymocytes and peripheral blood lymphocytes) have been followed up using light and electron microscopes. Differences have been revealed in the formation of death stages under natural physiological conditions and after gamma-irradiation. High radiation doses are shown to interfere with the process of nuclear chromatin condensation characteristic of the natural physiological death of cells.

[Dynamics of early postradiation changes in capillary endothelium (quantitative electron microscopic analysis]. / Dinamika rannikh postradiatsionnykh izmenenii éndoteliia kapilliarov (kolichestvennyi élektronno-mikroskopicheskii analiz).

Oedema, breakage and fragmentation of plasmolemma and mitochondrial damages developed in rats 1-48 h following total-body X-irradiation (4.5 Gy). These changes were most pronounced 2-6 h after exposure, when they spread over 20-30% of the population, and accompanied by the appearance of wide gaps in the endothelial layer and maximal accretion of free lipids in the endotheliocyte cytoplasm. Changes in the sizes and number of mitochondria were responsible for the tendency toward the increase in their relative total volume which was most pronounced after 12 h.

[Change in the myocardial capillary endothelium in the early periods after x-ray irradiation (an electron microscopic study)]. / Izmenenie éndoteliia kapilliarov miokarda v rannie sroki rentgenovskogo oblucheniia (élektronno-mikroskopicheskoe issledovanie).

According to the data of quantitative electron microscopic analysis in rats 1-48 h after total x-ray irradiation (450 rad) the number of microvesicles in endothelial capillaries decreases. Increasing size of the microvesicles and appearance of vacuoles does not compensate decreased total transport volume of these structures. After irradiation, in most capillaries the endothelial layer does not change its thickness; neither lesions in intracellular contacts nor formation of holes are observed. Both width of pericapillary zones and total volume of interstitial space in the myocardium do not change during the time of investigation.

[Nuclear proteins and DNA in the myocardial myocytes in compensatory cardiac hypertrophy]. / Iadernye belki i DNK v miotsitakh miokarda pri kompensatornoi gipertroffi serdtsa.

Using cytophotometry, the amount of DNA, total nuclear proteins and of histones were studied in the myocardial cells during days 21--36 of experimental compensatory hypertrophy of the heart (in rats). The enlargement of myocardial nuclei during the cardial hyperfunction was accompanied by accumulation of total nuclear protein, in particular, the histone fraction, without distinct changes in DNA. Analysis of correlations between nuclear proteins and DNA in the myocardial cells allows to reveal a delayed accumulation of histones in the big and gigantic nuclei, with a superfluous increase in non-histone nuclear proteins. In middle-sized nuclei, non-histone proteins have little changes against intensive accumulation of histones.