Biomedical subjects
Publications and source records attributed to V A Shakhlamov.
Hybrid heliocomposites were used for repair of the carious tooth crown. Ultrastructural study of mucosa biopsy specimens from sites adjacent to the filling 3 weeks after treatment showed that Charisma, Herculite, and Esterfil Ca filling materials led to degenerative changes in the mucosa, while Filtek Z-250 heliocomposite caused no pathological changes in the gingiva at the site of contact.
Using the methods of light and electron microscopy, morphometric and functional characteristics of mast cell (MC) populations were studied in the mammary gland (MG) and regional lymph node (RLN) at different stages of breast cancer (BC) induced in 120 outbred female albino rats with the body mass of 120-150 g. BC was induced by subcutaneous injections of chemical cancerogen N-methyl-N-nitrosourea. MC numbers and activity in MG and RLN were found to increase at all stages of BC formation studied (64-180 days of cancerogen exposure). Gradual increase in MC degranulation rate and degree, MC disintegration closer to the center of the tumor, together with the appearance in the peritumorous tissues, in the tumor itself, and in RLN of numerous small, immature MC, by their morphometric parameters identical to the intestinal mucosal MC, may presumably indicate the decompensation phenomena in the system and of the approaching of process terminal stage.
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The damaging effect of aluminum ions (Al3+) on the organism is widely investigated in clinics and experiments that indicate its role as a participant in the synthesis of precursors for amyloid proteins and as a potential agent in the ethiology of Alzheimer's disease. It has been shown that Al produces neurotoxic effects. We established that AlCl3 produces degenerative changes in the ultrastructure of Hasserian neurinoma cells in vitro and in L929 fibroblast cells. Proline-rich peptide-1 (PRP-1) isolated from neurosecretory granules of bovine neurohypophysis is a potent antineurodegenerative agent against spinal cord hemisection and crush syndrome-induced neurodegeneration of brain and spinal cord neurons. PRP-1 is one of the neurotrophic brain factors. By electron microscopic study of the rat hippocampus and other tissues, we succeeded in visualizing the epithelioprotectory effect of PRP-1, contributing as a powerful agent in removal of aluminum accumulation in different tissues in experimental aluminum neurotoxicosis.
Morphological equivalents of hepatocyte response to environmental factors of various intensity, associated with biochemical processes and directed at cell survival were studied in white outbred male rat using morphological (light and electron microscopy, histoautoradiography) and biochemical methods. As judged by the responses of intracellular structures, an exposure to hydrogen sulfide-containing gas, a pathogenic environmental factor, results in unequal changes in hepatocytes in different lobule zones. Small doses cause an activation of metabolic processes in hepatocytes that have plastic directivity. High doses of hydrogen sulfide-containing gas mixture result in the appearance of some signs of hepatocyte adaptation to extreme situation. Positive dynamics of structural modifications of the liver after the administration of nootropil and vitamin complex with antioxidant properties as correcting substances, indicates the reversibility of hepatocyte changes following long-term (up to two weeks) exposure to low doses and short-term exposure to high doses of hydrogen sulfide-containing gas mixture.
We studied ultrastructural and morphometric characteristics of nerve cells and myelinated fibers in the cerebral cortex after chronic exposure to natural gas containing hydrogen sulfide in low concentrations. Radioisotope assay revealed activation of protein synthesis in nerve cells after chronic exposure to natural hydrogen sulfide-containing gas in low concentrations (10 mg/m(3)by H2S) for 2 weeks. After 1 month the ultrastructure of myelinated fibers was characterized by sectorial loosening and demyelination.
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In experimental animals exposed to hydrogen sulfide-containing gas, electron microscopic study of cerebral cortex indicated the variability in the reaction of layer V neurons: along with neurons demonstrating irreversible damage, some cells with single signs of alteration were found. The reaction of different types of glial cells was also non-uniform. During initial 12 h following single exposure, oligodendrocytes showed the signs of intensified endocytosis. Following repeated exposures, severe destructive changes were found in myelinated nerve fibers and in single neurons, in which the karyolysis and cytoplasmic swelling were observed.
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Experiments were performed on 24 male Wistar rats weighing 210 +/- 14 g. Depending on the activity in the open field test, all rats were divided into behaviorally active and passive subgroups. Water-immersion stress (2 hrs) followed by 2-hrs rest period was used as the model of acute emotional stress. Tissue samples from aortic ascending arch were taken from control and stressed rats immediately after decapitation and used for further electron microscopy. The number of micropinocytosis vesicles along the free and basal layers of the cytoplasm and the area of mitochondria were determined. Emotional stress was shown to intensify metabolic processes involving micropinocytosis vesicles between the aortic lumen and its wall. Passive rats display the most severe alterations induced by stress (damages of aortic endotheliocytes, partial regeneration of the plasmalemma by membranes of micropinocytosis vesicles, and decrease in the average area of mitochondria). Morphological equivalents of the initial stages of emotional stress-induced formation of fibrous changes in the aortic arch intima are believed to be found. Such changes can lead to the appearance of atherosclerotic patches.
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Spinous layer of human epidermis was studied in control group (2 human subjects) and in 16 patients with thermic lesions prior to and following ultraviolet laser therapy (UVLT) of ultraviolet irradiation (UVI). Skin biopsy was performed in each patient on undamaged regions (individual control). Chemical elements (Ca, K, Cl, Mg, Na and Al) content prior to and following treatment was compared. Patients with equal stage (IIIB) and localisation of lesion were selected. Bioptates were obtained for diagnostic purposes. UVLT was established to prompt normalization of the content of chemical elements named in epitheliocytes of human epidermis in IIIB lesions whereas UVI does not cause this effect at the same conditions. It is proposed that this difference is dependent on the origin of appropriate irradiations.
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The possibility and applications of quantitative dry mass and water content mapping using an image analysis of darkfield intensity digitalization were shown on ultrathin freeze-dried cryosections. The distribution map obtained may be further used both for direct measurements of local dry mass and water content under physiological state and pathological disorders and for calculation of the concentration values obtained by quantitative X-ray mapping on freeze-dried cryosections in terms of millimoles per litre of cellular water.
Under increased muscular activity in some muscular fibers disintegration areas of myofibrillar apparatus has been revealed. Migration of myonuclei into these microregions starts the mechanism of their segregation due to plasmolemma produced from the reticulum sarcoplasmaticum and triad systems surface. After plasmolemma production in "sarcocytes" intensive development and differentiation of organellae occur. As a result of differentiation "sarcocytes" transform in to myosatellitocytes of type-2 and migrate under lamina externa muscular fibers. So, a hypothesis about formation of myogenic tissue's cellular phase from the myosymplastic one has been confirmed.
Experiments were made on 40 immature guinea--pigs which were divided into two groups. 20 animals received intraduodenal injections of cholera toxin and 20 others were injected normal saline (groups I and II, respectively). Group I animals exhibited a rapid fall in one--cell secretion of XS recorded on hour 6-12 after the injection of cholera toxin. Inhibition of functional activity was associated with defected synthesis of granules in the cells of Paneth.