Smooth muscle tissue (SMT) is one of the main structural components of visceral organs, acting as a key factor in the development of adaptive and pathological conditions. Despite the crucial part of SMT in the gastrointestinal tract activity, the mechanisms of its gravisensitivity are still insufficiently studied. The study evaluated the content of smooth muscle actin (α-SMA) in the membranes of the gastric fundus and jejunum in C57BL/6N mice (30-day space flight), in Mongolian gerbils Meriones unguiculatus (12-day orbital flight) and after anti-orthostatic suspension according to E.R. Morey-Holton. A morphometric analysis of α-SMA in the muscularis externa of the stomach and jejunum of mice and Mongolian gerbils from space flight groups revealed a decreased area of the immunopositive regions, a fact indicating a weakening of the SMT functional activity. Gravisensitivity of the contractile structures of the digestive system may be due to changes in the myofilament structural components of the smooth myocytes or myofibroblast actin. A simulated antiorthostatic suspension revealed no significant changes in the content of the α-SMA expression level, a fact supporting an alteration in the functional properties of the muscularis externa of the digestive hollow organs under weightless environment. The data obtained contribute to the novel mechanisms of the SMT contractile apparatus remodeling during orbital flights and can be used to improve preventive measures in space biomedicine.

Introduction: Glucocorticosteroid therapy is the basic therapeutic option for rheumatoid arthritis; however, long-term treatment with low and medium doses is associated with the development of negative side effects. As reported, oxidative stress is crucial in the pathogenesis of rheumatoid arthritis. Therefore, pharmacotherapy that combines application of methylprednisolone pulse therapy and an aqueous molecular hydrogen solution seems to be a reasonable treatment option in these cases. Materials and Methods: The study of the effectiveness of combined pharmacotherapy for rheumatoid arthritis was carried out on mature male rats. Rheumatoid arthritis was simulated by introducing bovine type II collagen into the right knee joint. Animals of the 1st – control – group received placebo; animals of the 2nd group received molecular hydrogen-enriched water intragastrically; animals of the 3rd group received methylprednisolone solution intravenously by catheterization of the tail vein, and animals of the 4th group received water enriched with molecular hydrogenintragastrically and methylprednisolone solution intravenously. After withdrawal of animals from the experiment, microsections of their joint tissues were analysed histologically and biomarkers of the joint inflammation were detected immunohistochemically. Results and Discussion: Morphological analysis of microsections taken from animals of the 4th group evidenced effectiveness of the combined therapy based on quantitative estimation of the inflammatory biomarker expression. Dynamic polarization of M1/M2 macrophage was manifested with high quality in animals of this group. Conclusion: The search for new therapeutic options for rheumatoid arthritis is expanded due to major antioxidant substances that can reduce duration of treatment, while ensuring positive dynamics of the course of the disease. Graphical

Acute herpes simplex virus infection in pregnant women results in intrauterine infection of the fetus in 45–50% of cases, thus being the cause of septic complications and severe somatic and neurological disorders in the newborn.The aim of the study was to investigate the placentas of new mothers with newly diagnosed herpes simplex virus type 2 infection (HSV-2) using histological and immunochemical methods.Material and methods. This histological study included 10 placentas of new mothers after operative delivery by caesarean section with newly diagnosed HSV-2 infection. The comparison group (control) consisted of 10 placentas of women with a physiological pregnancy. Histological sections of the placenta were stained with hematoxylin and eosin, Giemsa's solution and Picro-Mallory staining. Identification of the pro- and antiinflammatory phenotype of macrophages (CD68, CD163), subpopulations of CD4 and CD8 lymphocytes, TLR4 receptor expression was performed by immunohistochemical method using specific antibodies. Quantification of the cell population and TLR4 receptors was performed morphometrically. The data obtained were statistically analysed using MS Excel (2016) and SPSS Statistics 17.0.Results. Morphological manifestations of acute herpes simplex virus infection were combined inflammatory and compensatory in nature in the third trimester of pregnancy. The histological picture of the fetal part of the placenta demonstrated a decreased number of M2 (antiinflammatory) macrophages and an increased number of M1 (pro-inflammatory) macrophages. The imbalance between CD163+ and CD68+ profiles of placental macrophages with the numerical predominance of the latter evidenced a pronounced cellular immune response; this, in turn, was supported by intense TLR4 immunopositive staining of the fetal part of the placenta. There was perivillous fibrin deposition of varying degrees, villus agglutination, and necrosis of trophoblast cells associated with a relatively small population of CD4+ and CD8+. Villitis of viral etiology was characterized by destructive infiltration of maternal CD8+ T-lymphocytes penetrating the chorionic villi, combined with activated macrophages in the villi of the fetal part of the placenta. Modifications in the proportion of immune cells during HSV-2 infection supported cytotoxic and autoimmune reactions in the placenta in response to HSV-2 introduction.Conclusion. The results obtained evidence the development of a pronounced immunopathological process in the tissues of the fetal part of the placenta, which results in the decreased protective and compensatory properties of the placenta and increases risk of perinatal complications.

The effect of altered gravity on the digestive system is one of the challenging issues in space biology and medicine. The study of the effect of weightlessness on the mast cell (MC) functioning in the gastrointestinal organs is determined by their multifunctionality and participation in the developing adaptive and pathological processes.   The aim of the study was to investigate the morphofunctional state of MCs in the stomach membranes of Wistar rats during 14 days of ground-based simulated weightlessness conditions and in a 3-day recovery period.   Material and methods. The experiment involved 3 groups of Wistar rats: control, experimental – exposed to antiorthostatic suspension – and a 3-day-recovery group, 7 animals each, respectively. Identification of MCs was carried out using May-Grunwald staining with additional staining with Giemsa solution and immunohistochemical tryptase detection. The results obtained were statistically processed with SPSS 13 using parametric and non-parametric criteria.   Results. A significantly increased number of metachromatic MC population was found only in the mucosa in animals of the antiorthostatic suspension and 3-day-recovery groups compared to the vivarium control. There was a sharp decrease in degranulating forms of MCs in the submucosalcoat in animals of the 3-day-recovery group compared to the control. A significantly increased number of degranulating forms of MCs was revealed in the muscle membrane in animals of the antiorthostatic suspension group. Immunohistochemical staining of MCs with antibodies to tryptase, in contrast to staining for metachromasia, allowed identifying a significant representation of tryptase-positive cells in the gastric mucosa in animals of the 3-day-recovery group. Conclusion. The results obtained support gravisensitivity of certain structural components of the stomach, and also evidence MC and their secretome participation in the developing adaptive responses to the effects of altered gravity both at the cellular and tissue levels.

Introduction: The human body is exposed to numerous chemical and biological environmental factors. Post-exposure allergic reactions are becoming increasingly common. Interacting substances enhance each other’s health effects and aggravate allergy symptoms. Registration of a high pollen count resulting from a gradual increase in ambient temperatures leads to disappointing forecasts of a high prevalence of allergic rhinitis (hay fever). Evaluation of public health monitoring data on drinking water and food quality has revealed the significance of such pollutants as nitrates and nitrites. The interaction between pollen and nitrates has not been studied although it is of interest in terms of potential health effects of combined exposures. Objectives: To evaluate morphological changes in the quantitative composition of mast cells using an aqueous solution of molecular hydrogen in an experimental model of hay fever aggravated by exposure to chemical agents. Methods: Male Wistar rats were selected for experimental modeling of allergic rhinitis and 34 groups of six animals each were exposed to pollen and chemical agents during 55 days. To assess morphological changes in the nasal respiratory mucosa, we stained tissues with Giemsa solution and also applied a combined staining technique (Patent No. 2781558 dated October 13, 2022). Study limitations: Groups for comparison of methods of administration of the aqueous solution of molecular hydrogen against the saline solution were not included. Results: The cell morphology analysis revealed quantitative and qualitative changes in the animal groups with single and combined exposure to pollen and chemical agents and confirmed the therapeutic and prophylactic effect of the aqueous solution enriched with molecular hydrogen. Conclusion: The combined exposure to pollen allergens and nitrates and/or nitrites induces significant mast cell activation compared to control and single exposure groups. Therapeutic and preventive effects of molecular hydrogen down-regulate mast cell degranulation.