MICROSCOPIC CHANGES OF THE KIDNEY IN EXPERIMENTAL HYPERHOMOCYSTEINEMIA ON THE BACKGROUND OF HYPER- AND HYPOTHYROIDISM

Hyper- and hypothyroidism are two typical clinical conditions that can cause a variety of metabolic changes, including impaired sulfur-containing amino acids metabolism, increased risk of cardiovascular disease, renal dysfunction, and renal failure. Hypothyroidism has been shown to be associated with increased serum creatinine, decreased glomerular filtration rate, and an increased risk of chronic kidney disease. At the same time, the pathophysiological mechanisms of renal dysfunction induced by excessive iodothyronine secretion are poorly understood. The aim of the study was to establish the reorganization of the kidney structural components under the conditions of experimental hyperhomocysteinemia (HHCy), hyper- and hypothyroidism and their combined effects. Thiolactone HHCy was simulated by administering to animals exogenous homocysteine ​​(HC) in the form of thiolactone at a dose of 100 mg/kg body weight once a day for 28 days. Hyperthyroidism was simulated by daily administration of L-thyroxine at a dose of 200 μg/kg on 21st day, hypothyroidism - daily administration of mercazolyl at a dose of 10 mg/kg on 21st day. Separate groups of animals were administered L-thyroxine and mercazolyl in parallel with HC. A significant degree of dystrophic changes in the structural components of the kidneys under conditions of simulated hyperthyroidism and HHCy was established. Signs of vascular insufficiency in the kidneys were detected. Deformation of renal corpuscles, single focal thickenings and destruction of the outer layer of the renal corpuscle capsule were observed, there was a narrowing of the urinary space in the capsule. Microscopic study of the kidneys of animals under the combined effects of hypothyroidism and HHCy revealed the most significant destructive-degenerative changes in the filtration and reabsorption apparatus of the organ on the background of significant vascular disorders. An increase in number of glomeruli and a decrease of the urinary space of the Shumlyansky-Bowman's capsule were observed in the renal corpuscles. Podocytes underwent significant destructive changes. Damage to the epithelium in the system of tubules was manifested by cell hypertrophy. Under the conditions of simulated HHCy, hyper- and hypothyroidism, and especially with their combined effect, there are significant disorders of the vascular bed with remodeling of the vascular wall. On the background of hemodynamic disorders, there are significant destructive and dystrophic changes in the epitheliocytes of the renal corpuscles of the Shumlyansky-Bowman's capsule, the proximal and distal tubules of the nephron, the filtration and reabsorption apparatus of the nephrons of the organ.

CORRELATION BETWEEN CONNECTIVE TISSUE METABOLISM AND THYROID DYSFUNCTION IN RATS WITH PERIODONTITIS

The aim of the study was to clarify mechanisms of the periodontitis development in rats with thyroid dysfunction based on a comparative analysis of the correlations between the connective tissue metabolism indices and the concentration of thyroid stimulating hormone, free thyroxine and free triiodothyronine in blood serum. 12-14-week-old inbred white male rats (n=48) were included to the experiment. They were randomly divided into the following groups: control; animals with a model of periodontitis; animals with periodontitis in a setting of hyperthyroidism; animals with periodontitis in a setting of hypothyroidism. Concentrations of free thyroxine, free triiodothyronine and thyroid stimulating hormone were assayed with ELISA method. Collagenolytic activity, content of glycosaminoglycans, free hydroxyproline, fucose, unbound with proteins were determined by the spectrophotometric method. The linkages between the studied indices were established on the basis of the results of the correlation analysis using the Pearson correlation coefficient. Our research has found different interconnections between the indices of connective tissue metabolism and free triiodothyronine, free thyroxine and thyroid stimulating hormone concentrations in case of experimental periodontitis combined with thyroid dysfunction, indicating that thyroid gland has regulatory influence on connective tissue metabolism. In hypothyroid rats more correlations have been established compared to the hyperthyroid rats.

INFLUENCE OF CHRONIC HYPERHOMOCYSTEINEMIA ON METABOLISM OF SULFUR CONTAINING AMINO ACIDS IN THE RATS' HEART AND BRAIN ON THE BACKGROUND OF HYPERTHYREOSIS AND HYPOTHYREOSIS

The effect of experimental HHCy on the processes of transsulfuration of sulfur amino acids in the tissues of heart and brain, the levels of HCy, cysteine, H2S in blood serum of experimental animals with hyperthyroidism and hypothyroidism has been studied in the research. The experiment was performed on white male rats with simulated HHCy, hyper- and hypothyroidism, HHCy with different thyroid function. In the heart, the activity of cysteine aminotransferase (CAT), γ-glutamate cysteine ligase (γ-GCL), sulfite oxidase (SO) was determined. In the brain, the activity of cystathionine-β-synthase (CBS), cysteine ​​dioxygenase (CDO), GCL and SO was determined. In serum the total level of HCy, cysteine ​​and H2S was evaluated. HHCy caused inhibition of transsulfuration pathway of cysteine in the brain that was evidenced by decreased activity of CBS and CAT in heart that caused increase in the level of HCy and cysteine ​​as well as decrease in the level of H2S in blood serum. Hyperthyroidism causes increased activity of CBS in brain and of CAT in heart. Hyperthyroidism leads to decrease in the level of HCy in blood serum compare to the control, as well as increase in the level of H2S compare to the group of animals with HHCy. Hypothyroidism causes inhibition of cysteine ​​metabolism, decrease in of HCy and cysteine levels. In cases of HHCy simulated by administration of thiolactone-HCy the activity of CBS and SO in the brain of rats, and CAT in the heart is increased. Hyperthyroidism causes increase of the activity of the CBS, CDO, and SO in the brain, as well as CAT in the heart. At the same time, the simultaneous administration of L-tyroxysin into the animals with HHCy leads to increase in the enzyme activity of CBS, CDO, γ-GCL and SO in the brain of the animals and increase of CAT and γ-GCL in the myocardium. Hypothyroidism in the brain of animals causes a decrease in the activity of the CBS, CAT and SO, and at the same time, the activity of SO only decreases in the myocardium of animals. An increase in the level of HCy and cysteine, a decrease in the level of H2S in the blood of experimental animals during hypothyroidism, as well as inhibition of the transsulfuration enzyme activity in the brain and heart are significant markers of the development of cardiovascular pathologies and mortality associated with hypothyroidism.

IMMUNOLOGICAL DISTRESS IN EXPERIMENTAL CRANIAL TRAUMA COMBINED WITH INSULIN DEPENDENT DIABETES (EXPERIMENTAL STUDY)

This article describes the immunological events and investigates important mediators of the inflammatory immune response after experimental cranial trauma combined with type I diabetes. It was shown that the rats with induced diabetes and traumatic brain injury suffered more profound damage to the immune system that was not restored back to the basal level within 14 days. Proinflammatory cytokine concentrations increased, while anti-inflammatory cytokine concentrations decreased by day 14, increasing risk for systemic inflammatory response syndrome and multi-organ failure. Factors responsible for humoral immunity and cell-mediated immunity were consistently lower by day 14, which might make diabetic rats more susceptible to infections compared to rats with brain injury alone.

Monoclonal antibodies identify residues 199-216 of the integrin alpha2 vWFA domain as a functionally important region within alpha2beta1

Integrin alpha2beta1 is the major receptor for collagens in the human body, and the collagen-binding site on the alpha2 subunit von Willebrand factor A-type domain (vWFA domain) is now well defined. However, the biologically important conformational changes that are associated with collagen binding, and the means by which the vWFA domain is integrated into the whole integrin are not completely understood. We have raised monoclonal antibodies against recombinant alpha2 vWFA domain for use as probes of function. Three antibodies, JA202, JA215 and JA218, inhibited binding to collagen, collagen I C-propeptide and E-cadherin, demonstrating that their function is important for structurally diverse alpha2beta1 ligands. Cross-blocking studies grouped the epitopes into two clusters: (I) JA202, the inhibitory antibody, Gi9, and a non-inhibitory antibody, JA208; (II) JA215 and JA218. Both clusters were sensitive to events at the collagen binding site, as binding of Gi9, JA202, JA215 and JA218 were inhibited by collagen peptide, JA208 binding was enhanced by collagen peptide, and binding of JA202 was decreased after mutagenesis of the cation-binding residue Thr(221) to alanine. Binding of cluster I antibodies was inhibited by the anti-functional anti-beta1 antibody Mab13, and binding of Gi9 and JA218 to alpha2beta1 was inhibited by substituting Mn(2+) for Mg(2+), demonstrating that these antibodies were sensitive to changes initiated outside the vWFA domain. Mapping of epitopes showed that JA202 and Gi9 bound between residues 212-216, while JA208 bound between residues 199-216. We have therefore identified two epitope clusters with novel properties; i.e. they are intimately associated with the collagen-binding site, responsive to conformational changes at the collagen-binding site and sensitive to events initiated outside the vWFA domain.