The aim: Was to clarify the general patterns of structural changes in the left ventricular myocardial capillaries in rats with spontaneous arterial hypertension. Materials and methods: Experiments were conducted on 50 ISIAH (inherited stress-induced arterial hypertension) line rats with arterial hypertension: juvenile young (45-day) and sexually mature (100-day) rats, as well as intact animals of the corresponding age. While extracted from the experiment rats of all experimental groups had their arterial pressure measured using a plethysmograph. Electron microscopic examination of the left ventricular myocardium and morphometric study of volumetric and quantitative densities, cross-section area, and form factor of micropinocytotic vesicles were conducted. Results: In sexually mature rats with arterial hypertension, a high level of pressure is maintained. In 45-day-old rats with arterial hypertension in endothelial cells of myocardial blood capillaries there is a hyperactivation of biosynthetic processes (euchromatic nucleus, large-sized mitochondria, ER canals, Golgi complex), which may be a manifestation of reactive processes in response to a non-stable increase in arterial pressure. In the 100-day rats with arterial hypertension, the mosaic of the ultrastructure of the myocardium blood vessels is preserved, but destructively-dystrophic changes become more expressive and involve not only the organelles but also the integrity of the endothelial cell itself. Destructively-dystrophic processes in rat capillaries are accompanied by compensatory and adaptive ones. This is manifested by activation of the transport of substances, both transendothelial and paracellular, and quantitative density of micropinocytotic vesicles increases statistically significantly. Conclusions: In myocardial capillaries of young (45-day) arterial hypertension rats, compensatory and adaptive changes are manifested by activation of biosynthetic processes in endothelial cells following a slight increase in micropinocytotic vesicles quantitative density and signs of destructive-dystrophic processes (minor edema and lysis of endothelial cell cytoplasm). In sexually mature (100-day) arterial hypertension rats in the blood capillaries of the myocardium, the destructive-degenerative changes increase is accompanied by preservation of signs of compensatory processes. Reducing the number of capillaries is offset by an increase in the number of micropinocytotic vesicles.

Introduction: In the treatment of hypothyroidism substitution therapy with L-thyroxine is used, it is also advisable to use the metabolites with membrane-stabilizing properties that normalize the metabolism in the body, for example, calcitonin, which significantly reduces the depth of the dystrophic phenomena in the myocardium. The aim was to study the patterns of structural changes in the left ventricular myocardial capillaries of rats with congenital hypothyroidism in combinative drug therapy with L-thyroxine and calcitonin. Materials and methods: 30 white Wistar line rats were used as experimental animals: 10 with treatment and 10 without as well as control – 10 intact Wistar line rats of the same age. Mercazolil was used to inhibit thyroid gland in order to model congenital hypothyroidism. After birth, the rats received L-thyroxine at a dose of 10 μg / kg per os daily, calcitonin at a dose of 1.0 MU / kg per day intramuscularly, then with mother’s milk, later by themselves for 100 days. The arterial pressure was measured in all experimental groups during extraction from the experiment by plethysmograph, their left ventricular myocardium was examined under electron microscope and micropinocytotic vesicles in their cells were studied morphometrically. Results: In rats with congenital hypothyroidism, for which L-thyroxin drug in combination with calcitonin was used as a substitution therapy, after pharmacological correction, in general there is no pronounced heteromorphism of the ultrastructure of the left ventricular myocardial blood capillaries, which was characteristic for animals without pharmacological correction. The analysis showed normalization of the content of free thyroxine in blood plasma and blood pressure of rats with congenital hypothyroidism after complex substitution therapy. Conclusions: In rats with congenital hypothyroidism, which received L-thyroxine and calcitonin at birth, the myocardium capillaries generally remain intact and have morphological and functional characteristics similar to intact animals, which is the theoretical basis for the need for calcitonin to be used in substitution therapy in hypothyroidism.

Aim: to analyze modern professional literature and summarize data on treatment methods for peripheral nerve injuries, taking into account the mechanisms of positive effects. The article presents an overview of possible methods for treatment of peripheral nerve injuries, fundamental classifications of peripheral nerve injuries, their differences are considered, pathophysiological mechanisms and the probability of spontaneous recovery depending on the degree of injury, general principles and conditions for successful regeneration of the peripheral nerve. Options, combinations, advantages and disadvantages of such surgical methods for peripheral nerve injury treatment as neurorrhaphy, autotransplantation and allotransplantation are described in detail, such terms as “small”, “large” and “critical” gaps between the nerve stumps are specified. Classifications and characteristics of conduits are described, types of synthetic conduits are considered. The use of drugs, Schwann cells, growth and neurotrophic factors, neural, embryonic and mesenchymal stem cells of various origins, exosomes of mesenchymal stem cells in the so-called “stem cell-free therapy” in treating this pathology is mentioned. Genetically modified mesenchymal stem cells, optokinetics are also noted, such physical methods for peripheral nerve injury treatment as short-term low-frequency electrical stimulation of the nerve, magnetic stimulation, low-intensity ultrasound, photobiomodulation therapy, photochemical bonding are discussed, indicating some mechanisms of their positive effects. Conclusions. Improving the quality of life and reducing the degree of disability in patients with injuries of the main nerve trunks depends on the combined use of a number of surgical, bioengineering and regenerative technologies. These involve the restoration of the anatomical continuity of the nerve, including through the use of natural or artificial elements, cellular technologies and the management of regenerative processes. Therefore, every time, a surgeon is facing a major challenge to create a combination of various means from the indicated basic components for the treatment of nerve damage in managing a particular patient. However, such a treatment approach requires proper competences of surgeons as well as specific material and technical bases in order to bring down the level of social tension in patients with injuries of the main nerve trunks.