The aim of the study was to compare two types of conduits made of either non-resorbable Reperen or resorbable Tissucol for their effects on the regeneration of the rat sciatic nerve under conditions of stump diastasis. Materials and Methods. The experiments were carried out using outbred white male rats of the reproductive age (n=14). The animals were divided into three groups: group 1, intact (n=5), used for studying the morphology of the sciatic nerve; group 2 (n=4) — nerve plastic surgery was performed using a conduit made of non-resorbable Reperen; group 3 (n=5) — surgery was performed using a conduit made of resorbable Tissucol. The animals were anesthetized with isoflurane. After a complete transection of the sciatic nerve in the middle third of the thigh, its stumps were inserted into a conduit of an internal diameter of 2 mm and a length of 10 mm, filled with saline. Diastasis of 5 mm in length was created by spreading the nerve ends and securing the epineurium to the tube edges with 8/0 polypropylene sutures. A total count of myelinated nerve fibers was performed in the area of repair (tubulation) and the distal part of the nerve; the formation of connective tissue sheaths was assessed 14 weeks after the operation. Results. According to the morphological assessment, both types of conduits (resorbable and non-resorbable) caused the similar number of fibers to restore in the distal part of the repaired nerve; clinical characteristics of the animals in both groups were close to each other and to the norm. Conclusion. The results allow us to consider the conduit made of non-resorbable Reperen as a device promising for neuroplasty along with the resorbable conduit made of Tissucol.

The aim of research is to study posthypoxic transformation of the colon wall using light and electron microscopy in an experimental model of rat offspring. Materials and methods. Chronic hypobaric hypoxia at different stages of pregnancy was simulated experimentally in 24 female white mongrel rats using a vacuum flow chamber with a rise to a height of 5000 m at a speed of 25 m/sec for 40 minutes. After delivery, the offspring were examined, subjected to hexenal anesthesia, and then removed from the experiment using decapitation. For light microscopy, resected sections of the small intestine and colon were stained with hematoxylin-eosin, and studied on Topic (Belgium, 2000) and Bio Blue (the Netherlands, 2013). Electron microscopic analysis was performed in a Morgagni 268D transmission electron microscope (FEI, USA). Results. Chronic hypoxia, simulated in the first trimester of pregnancy, led to significant changes in the intestinal mucosa in combination with the growth of the connective tissue component in the muscle layer. The risk of developing dynamic intestinal obstruction occurred in the offspring of all groups, this was supported by an increase in the fibrous tissue of the intestinal wall. Pronounced changes in the microcirculatory bed were detected in animals of groups II and III, as they were predisposed to develop pre-ulcer and ulcerative defects in the wall of the small intestine. At the submicroscopic level, it was detected that both adaptive and destructive processes occurred in the wall ultrastructure of the descending colon of the rat offspring after hypoxic exposure in the prenatal period in animals of all experimental groups. In the microcirculatory bed, there was an increased venous congestion, with the most pronounced changes observed in the third trimester. Conclusion. Thus, the study of hypoxia in the experiment allows investigating more about all the mechanisms of the pathological process and to translate theoretical knowledge into practical medicine.

The aim of the investigation was to assess the parameters of urgent adaptation of the heart and peripheral vasculature to single physical exercises to determine an individually safe value of motor activity.Materials and Methods. The experiments were carried out on 84 mongrel male dogs. Physical exercises were modeled in laboratory environment by treadmill run. Three types of exercises were used in the experiment: mild, optimal and excessive. Exercise duration was controlled individually, for each animal considering cardio-respiratory system state by heart rate. Cardiac work was assessed by echocardiography and electrocardiography, peripheral circulation -by hindleg rheovasogram.Results. Experimental findings indicate significant alterations in cardiac conducting system under single physical exercises. A single mild exercise causes the increase of minute blood output due to heart rate increase. Hind leg muscular blood filling decreases. An optimal exercise results in minute blood output increase due to stroke blood volume growth. Myocardial contractility increases. Muscular blood filling rises. In excessive load increased stroke output is accompanied by left ventricular cavity dilatation. Pulse volume decreases, peripheral vasculature elasticity reduces, and hind leg muscular venous outflow gets worse.Conclusion. urgent adaptation of the heart and peripheral vasculature in single physical exercises shows as a marked response to a simulated factor. The technique to assess the body adaptation considering cardiovascular system condition enables to calculate individual volume of physical activity and develop recommendations for it to be used efficiently in medicine.

The aim of the investigation was to reveal the spatial organization types of sinoatrial nodes in animals with different levels of body functional reserve after a single maximal exercise.Materials and Methods. The research was carried out on 24 male mongrel dogs. Treadmill run under laboratory conditions was used to model a single maximal exercise. The exercise time was individual for each animal due to its cardio-respiratory system. A body functional reserve level was determined by the running time to refusal and the heart rate (HR) during the exercise. We studied the sinoauricular area structure using light and transmission electron microscopy. Tissue organization of myocardium was analyzed using the methods of stereology.Results. According to HR dynamics, we distinguished two main types of functional response to maximal (excessive) exercise: type I, high HR during the running, and type II, low HR. The response types on exercise also differed in the running time and resting HR (p<0.05).Based on stereological test findings we described the peculiarities of spatial organization of conductive and contractile myocardium in animals with different functional responses characterized by various ratios of the main tissue components. Stereological parameters in type I animals were similar to those in intact animals of a control group. Conductive and contractile myocardium in type II animals significantly differed in a relative volume of cardiomyocytes and connective tissue components from those in controls and type I animals.Conclusion. The results of morphological studies of sinoauricular region in animals with different levels of functional body reserve compared to physiological parameters enable to predict the structural changes in the sinoatrial node area after an excess motor load.

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