Vol 155, No 3 (2019)

Objective - to examine changes in the DNA methylation status in the cells of neocortex and hippocampus in rats exposed to different modes of hypobaric hypoxia. Material and methods. The study was performed on 24 adult male Wistar rats (180-200 g). The animals were exposed to various modes of hypobaric hypoxia using flowing hypobaric chamber. The brain sections were immunohistochemically stained against 5-methylcytidine in DNA. The changes in the total number of cells and their division into two categories based on the intensity of immunohistochemical reaction to 5-methylcytidine were evaluated. Results. Severe hypobaric hypoxia (SHH) led to elevation in the quantity of intensely labeled immunopositive cells in the neocortex 3 h after the exposure. Preventive neuroprotective exposure to three (but not one) sessions of mild hypobaric hypoxia (MHH) led to a decrease in the number of intensely immunopositive cells in the neocortex in response to subsequent SHH. No significant changes were found in the hippocampus. Conclusions. The opposite changes in the level of DNA methylation in rat neocortex were revealed which depend on the degree of hypobaric hypoxia: damaging SHH was associated with gene repression, and adaptogenic MHH caused their activation.

Objective - to study the effect of the structural analogue of taurine (N-isopropylamide-2-(1-phenylethyl)aminoethanesulfonic acid) on the spiral organ of the guinea pig. Materials and methods. The ultrastructure of the spiral organ was studied in 60 guinea pigs (weighing 250-400 g), divided into 4 experimental groups. The experiment was carried out under the conditions of an exposure of an organism to a metered-dose noise-vibration factor with or without treatment with a metabolic drug (a structural analogue of taurine) - N-isopropylamide-2-(1-phenylethyl)aminoethanesulfonic acid compound. After the experiment, guinea pig spiral organs were subjected to morphological study using scanning and transmission electron microscopy. Results. Structural changes were detected in the sensory hairs of the receptor cells of spiral organ, and the bundles of stereocilia of the outer hair cells were more vulnerable compared with the inner hair cells. The use of the bioactive analog of taurine contributed to the prevention of changes in the ultrastructure of hair cells in all parts of the cochlea exposured to noise-vibration factor compared with animals that did not receive the drug. Conclusions. The electron microscopic results of the study indicate that N-isopropylamide-2-(1-phenylethyl)aminoethanesulfonic acid has an otoprotective effect, contributing to better preservation of the ultrastructure of hair cells in spiral organ, more pronounced when the tested compound was used prophylactically.

Objective - comparative experimental study of the changes of the structure, proliferative and metabolic activity of the oral mucosal epithelium after administration of cytostatic drug and morphogen with a special reference to the heteromorphism of this tissue. Metarial and methods. Using histological, morphometric and quantitative histochemical methods, the changes of lingual epithelium were studied in 45 mature outbred albino mice after 5 days of intraperitoneal injections of 400 mg/kg of cytostatic drug cyclophosphamide (CY) to 15 animals and 100 μg/ kg of hydra peptide morphogen (HPM) to another 15. Control group included 15 intact mice. Material was obtained 24 hrs after the last injection of drugs. The characteristics of the epithelium were studied on the ventral (VS) and dorsal surfaces (DS) of the tongue, in the areas of filiform papillae and between them. Results. CY administration resulted in the damage of the surface epithelium which was more expressed on lingual VS, where cell proliferation processes were compromized. HPM injections induced an increase of the epithelial proliferative activity, which was also more pronounced on the VS of the organ. Metabolic processes in the epitheliocytes, as evaluated by succinate dehydrogenase activity, had a different intensity in various topographical zones of the organ; after CY and HPM administration, more pronounced changes were observed on the DS. Conclusions. CY and HPM were found to induce significant multidirectional changes in the structure and metabolic activity of the lingual surface epithelium. Under their influence, the heteromorphism of this tissue was significantly increased. HPM may find an application in the treatment of the diseases associated with the disorders of the processes of cell and tissue proliferation and differentiation.

Objective - to study rat liver morphology following the administration of effective doses of CCl4 in animals with varying intake levels of B vitamins (B1, B2, B3, B6) and mineral substances (Fe3+ and Mg2+). Materials and methods. The animals were divided into six groups, three control and three experimental, 30 males in each. The rats in the control groups K-75, K-30 and K-19 received rations with 75 %, 30 % and 19 % of vitamins B1, B2, B3 and B6 and minerals (Fe3+ and Mg2+), respectively. Rats in experimental groups O-75, O-30 and O-19 received the same rations and for two months once a week were intraperitoneally injected with CCl4. Each animal received the total amount of 6,5 g CCl4 per kg of body weight. Morphological study of the liver was carried out at the end of the experiment. The results were evaluated using a semi-quantitative SAF scale. Results. The correlation between the severity of the liver damage and the degree of diet vitamin-mineral deficiency was found. The most significant pathological changes were observed in animals from O-19 group, in O-30 and O-75 groups the pathomorphological changes were approximately at the same level, i. e the severity of the toxic effect decreased in sequence O-19>O-30=O75. Conclusions. The vitamin-mineral deficiency model may be recommended for use in subchronic and chronic toxicological studies, including comprehensive study of low-toxic factors.

Objective - to study the role of growth, vascular and immune factors in the reparative processes in tissues surrounding the femur fracture area following titanium implant insertion. Material and methods. In the course of the experiment, a morphometric and immunohistochemical assessment of the condition of tissue adjacent to the osteosynthesis area was carried out in 20 Wistar rats. Titanium implants with and without calcium phosphate coating were used for femur fractures; no bone fragments alignment was done. Two autopsy tissue samples from the area adjacent to the site of injury were obtained from each experimental animal. The relative density of capillaries, the parenchymal-stromal ratio and the level of expression of the growth factors VEGF-A and TGF-β were estimated. Results. It was shown that the reparation of muscle and connective tissue during osteoreparation without implant insertion predominantly occurred through the formation of granulation tissue with abundant proliferating cells. The proliferative stage in the tissues of animals which received an uncoated titanium pin was characterized by the presence of numerous degraded collagen fibers and adipocytes. In animals which received a calcium-phosphate coated pin a granulation tissue formed, where fibroblasts were the most abundant cell type in the area between the individual muscle fibers. High expression of growth factors (TGF-β and VEGF-A) was found in the muscles of the animals which received no implant. Conclusion. The positive effect of the calcium phosphate coating of the implant on reparative processes in the tissues adjacent to the osteosynthesis area, including an increase in the volume density of endomysium and a decrease in the expression of growth factors, was found.

The article provides an overview of the modern concepts of the structural and functional characteristics of specialized intercellular junctions in the spermatogenic epithelium of convoluted seminiferous tubules of adult rats, including the basal and apical ectoplasmic specialization and the basal and apical tubulobulbar complex. Specialized intercellular junctions in the testes are of critical importance in spermatogenesis regulation: their alteration and destruction lead to disruption of germ cell formation and infertility, which makes it essential to study them.