Objective. Emerging data indicate that oxidative stress is closely associated with the pathogenesis of cardiovascular disease in type 2 diabetes mellitus (T2DM). The present study aimed to assess the effect of the most abundant flavonoid in the human diet quercetin (Q) on the myocardial redox status in rats with T2DM.
Methods. T2DM was induced in male Wistar rats by a high caloric diet (for 14 weeks) and two streptozotocin (25 mg/kg b.w.) injections applied in four weeks of the diet, once a week for two weeks. The Q was administered intragastrically by gavage in a dose of 10 or 50 mg/kg of the body weight for 8 weeks starting from the 8th day after the last streptozotocin injection. The control rats received citrate buffer and seven days after the last STZ injection, basal glucose levels were measured in all animals.
Results. Administration of Q increased insulin sensitivity in diabetic rats with more pronounced effect at a dose of 50 mg/kg b.w. The Q also decreased free radical oxidation in the heart mitochondria of diabetic animals, thus limiting the formation of advanced oxidation protein products in a dose-dependent manner and normalized the activity of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, glutathione reductase) in cardiac mitochondria independently of the dose used. In addition, the Q in both doses prevented the development of oxidative stress in the T2DM rats cardiomyocytes by reducing NADPH oxidase and xanthine oxidase activities.
Conclusions. The findings demonstrate that Q in both doses 10 mg/kg and 50 mg/kg can protect from the development of oxidative stress in cardiomyocytes in the diabetic rats. The present data indicate that the use of Q may contribute to the amelioration of cardiovascular risk in patients with T2DM.
Background. The use of antimicrobial peptides is one of the possible ways to overcome the threatening rapid growth of resistance of microorganisms to traditional antibiotics. Of the particular role in this context is gramicidin S (GS), which is used for topical medical applications for over 70 years. An acute hemolytic side effect of GS on human cells prevents its systemic use. Understanding the molecular mechanisms of interaction of GS with biological membranes will enhance its bactericidal effect on the one hand, and reduce the negative side effects on human cells and thus expand the range of antibacterial peptides to combat infectious diseases caused by resistant microorganisms.
Objectives. Study of the effect of different doses of the antimicrobial oligopeptide antibiotic GS on the morphological and electrophysical characteristics of human erythrocytes during in vitro incubation.
Materials and methods. Morphological changes of erythrocytes of healthy donors after preliminary incubation with GS at concentrations 5–40 μg/ml were studied by flow cytometry using resistance pulse spectroscopy. Single-cell volume, erythrocyte volume distribution in the population was measured, and the electrical breakdown potential of the human erythrocyte plasma membrane was determined.
Results. Incubation of human erythrocytes with sub-lytic concentrations of GS is accompanied by a redistribution of erythrocytes in this population by volume with an increased number of smaller erythrocytes with less resistance of the membrane to electrical breakdown. However, increasing the concentration of GS to 40 μg/ml leads to an increase in the proportion of cells of increased volume with increased resistance to electrical breakdown of the membrane. Possible mechanisms of morphological changes of erythrocytes under the action of GS are discussed.
Conclusions. Incubation of erythrocytes with GS at concentrations 5–40 μg/ml is accompanied by a redistribution of cells by volume and changes in the resistance of their plasma membrane to electrical breakdown due to destabilizing membrane-tropic action of the peptide, microsimulation, or cytoskeleton rearrangement.
The platelet component of hemostasis in rats with metabolic syndrome induced by a high-fat diet under conditions of eu- and hypoestrogenism.
It was found that in females receiving a high-fat diet, there is an increase in the degree, and in ovariectomized rats kept on a standard
diet, the rate of ADP-induced platelet aggregation increases. The combined effect of diet and estrogen deficiency causes a more pronounced increase
of both studied indicators, which indicates the summation of their procoagulant effect.
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