[Development and assessment of efficacy of L-polylactide matrix for creation of a tissue-engineered vascular graft]. / Razrabotka i otsenka éffektivnosti matritsy iz L-polilaktida dlia sozdaniia tkaneinzhenernogo sosudistogo implantata.

In order to create a tissue-engineered vascular graft we elaborated a matrix consisting of nanofibres of biodegradable polymer L-polylactide. We worked out the methodology of crystallization of the matrix on a rod, making it possible to manufacture specimens possessing strength and deformity characteristics superior to those of native vessels. This was followed by a series of chronic experiments on implanting the elaborated matrix into the abdominal aorta of rats for the duration of up to 16 months. We obtained satisfactory parameters of the patency of the matrices (71%). According to the findings of histological examination, in the course of time there occurred biodegradation of the matrix and formation of a new vascular wall, with no evidence of either inflammation or neointimal hyperplasia in the zone of the anastomoses. Resorption of the polymeric fibres commenced 12 weeks after exposure and completely terminated after 64 weeks. By that time, both neointima and neoadventitia were formed, whose composition and structure were close to those of the native vessel. Insufficiently high mechanical properties of the zone of reconstruction turned out to be the cause of the formation of aneurysms.

[Activity of lactate dehydrogenase in the brain cortex and hippocampus of Mongolian gerbils after global ischemia and reperfusion injuries].

Cerebral ischemia results in severe derangements of energy metabolism in the nervous tissue including activation of glycolytic pathway. Activity of cytosolic lactate dehydrogenase (LDH) in the specific brain structures remains unclear. The recent study was aimed at investigation into the LDH activity in the cytoplasm of both hippocampal and cortical neurons in Mongolian gerbils (Meriones unguiculatus) at different durations of reperfusion after global ischemia. Analysis showed that the activity of LDH in pyramidal neurons of various hippocampal areas and neurons of II, III and V cortical layers after 7-minute forebrain ischemia depended on both localization of the neurons and duration ofreperfusion. In general, the changes in postischemic cytosolic LDH activity include significant decrease in the LDH activity 2 days after reperfusion with varying degree of recovery on day 7 of reperfusion.

[Morpho-functional changes of hippocampal CA1 area in Mongolian gerbils after ischemic postconditioning].

The aim of this study was to determine the effect of ischemic postconditioning on hippocampal CA1 neuronal survival and cytoplasmic activity of lactate dehydrogenase (LDH) in the gerbil model of cerebral ischemia-reperfusion injury. Ischemia was induced by bilateral common carotid artery occlusion (for 7 min) in male Mongolian gerbils (Meriones unguiculatus). Ischemic postconditioning protocol comprised 3 cycles of 15 s reperfusion/15 s ischemia. After 48 h of reperfusion, CA1 neuronal death was detected by Nissl staining and the cytoplasmic LDH was demonstrated histochemically in CA1 area of the hippocampus with a quantitative cytophotometric assessment of the enzyme activity. The results have shown that 7 min ischemia resulted in a significant decrease in the number of viable neurons (up to 24%) in the CA1 area of hippocampus; in addition, it reduced the activity of LDH in these neurons (from 0.260 +/- 0.009 to 0.190 +/- 0.006 relative units). The application of ischemic postconditioning significantly increased the number of viable neurons (up to 52.9%, P < 0.01) in the CA1 area of hippocampus, and it was accompanied by an increase in the activity of LDH (0.240 +/- 0.008 relative units, P < 0.001).

[Ultrastructural and metabolic characteristics of the thyrocytes exposed to cyclophosphane]. / Ul'trastrukturnye i metabolicheskie kharakteristiki tirotsitov pri deistvii tsiklofosfana.

Ultrastructural, morphometric and metabolic characteristics were studied in thyrocytes of 96 mice treated with immunosuppressing and cytostatic drug cyclophosphamide (CY), injected intraperitoneally every other day either for a short time (up to 6 days) in high doses (400 mg/kg) or for a long time (up to 70 days) in moderate doses (40 mg/kg). High doses of CY caused the reduction in thyrocyte height, NADH-diaphorase activity in their cytoplasm and protein content in the follicular colloid as compared to these parameters in a control group. The cisterns of rough endoplasmic reticulum (RER) underwent swelling and deformation with the loss of electron density of their contents. This was accompanied by mitochondrial swelling with matrix clarification and disorganization of cristae and an increase in the amount of cytoplasmic lipid droplets. Following long-term administration of CY in moderate doses the thyrocyte height exceeded that one in control group, while the NADH-diaphorase activity changed insignificantly and protein concentration in colloid increased. In the majority of thyrocytes the nucleus and major organelles retained their normal structure, while in some cells the cisterns of RER appeared dilated. Acid phosphatase activity was unchanged in both experimental groups. Thus, despite the approximately equivalent total CY dose in experimental groups, its damaging effect on thyrocytes was expressed much less in animals receiving the moderate doses of CY, that, probably, could be explained by the lack of CY cumulative effect and high rate of its metabolic degradation and clearance.

[Morphofunctional changes in the thyroid gland after cyclophosphamide administration and their reversibility]. / Morfofunktsional'nye izmeneniia shchitovidnoi zhelezy pri vvedenii tsiklofosfana i ikh obratimost'.

By using histological morphometric stereological and quantitative enzyme histochemical methods, structural and metabolic changes in thyroid gland after short-term treatment with high doses of cyclophosphamide (GY) were studied. Mice were treated with 400 mg/kg of GY every 48 h for up to 7 days(1-4 i.p. injections). To assess the effect of CY and its reversibility thyroids were studied on the day following each injection and 5-15 days after three injections. CY treatment caused significant dose-dependent structural and metabolic changes in thyroid gland which included vacuolization and destruction of thyrocyte apical cytoplasm, focal follicular wall destruction leading to the fusion of some follicles, reduction in volume fractions of epithelium with the condominant increase in volume fraction of colloid and stroma, decrease in follicular cell height, decline in both thyrocyte cytoplasmic NAD-H-diaphorase activity and vascular alkaline phosphatase activity. These changes were not completely reversible by day 15 after the last injection of CY.

[Modernization of the methods for detecting NADH diaphorase and glucose-6-phosphatase at the light-optical level]. / Modernizatsiia metodik vyiavleniia NADH-diaforazy i gliukozo-6-fosfatazy na svetoopticheskom urovne.

A technique for NADH-diaphorase and glucose-6-phosphatase activity visualization at the light microscope level has been essentially modified by the use of a short pre-fixation of cryostat sections in a gluteraldehyde-containing fixative followed by a prolonged (18-20 h) incubation in the chilled (4-6 degrees C) standard media. Besides, for revealing NADH-diaphorase Triton X-100 is recommended to add to the incubation medium. The offered technical modifications secure a high staining intensity and specificity of both histochemical reactions tested without any substantial sophistication of the procedure.

[Changes in enzyme activity in postoperative myocardial biopsy samples after surgical correction of late-stage rheumatic heart defects]. / Izmenenie aktivnosti fermentov v operatsionnykh biotatakh miokarda pri khirurgicheskoi korrektsii revmaticheskogo poroka mitral'nogo klapana pozdnikh stadii.

A direct statistically reliable correction of decrease of the enzymes with the initial state of the patients has been established in an analysis of 25 patients aged from 18 to 60 years in prosthesis of+ the mitral valve (n-9) and closed mitral commissurotomy (n-16). The enzyme activity after prosthesis of+ the mitral valve was twice lower that after closed commissurotomy. Activity of ATP-ase of myofibrils proved to be most sensitive to negative factors of operation.