Hypochlorous acid-induced lysis of human erythrocytes. Inhibition of cellular damage by the isoflavonoid genistein-8-C-glucoside

Erythrocyte damage induced by hypochlorous acid (HOCl) results in cell lysis developing with time after the oxidant is removed (post-hemolysis). The apparent rate constant of post-hemolysis depends on time of incubation in the presence of HOCl and concentration of this oxidant. HOCl-dependent damage of erythrocyte membranes is associated with uncompetitive inhibition of the membrane-bound acetylcholinesterase. Genistein-8-C-glucoside is an isoflavonoid isolated from the flowers of Lupinus luteus L.; in aqueous solution, genistein-8-C-glucoside (0.5-2 mM) efficiently inhibited HOCl-induced damage to erythrocytes similar to the known HOCl scavengers taurine and reduced glutathione. This bioflavonoid can protect the erythrocyte membrane (and to a lesser extent, intraerythrocytic components) by interacting with the reactive chlorine species including hypochlorous acid and membrane-bound chloroamines formed in the reaction of HOCl with erythrocyte membrane proteins.     

Cenotic positions and ecological amplitudes of mosses in the vegetation of the Great Vasyugan Swamp

The results of long-term bryological investigations in the Great Vasyugan Swamp are summarized. The cenotic and bryological diversity of the system is described: It includes 8 types of mire communities and 122 moss species. Ecological optimums and amplitudes in Ramenskii’s scales have been calculated for all the types of mire communities and common moss species.     

Effect of chitosan on tobacco mosaic virus(TMV) accumulation,hydrolase activity,and morphological abnormalities of the viral particles in leaves of N. tabacum L. cv. Samsun

The effect of chitosan on the development of infection caused by Tobacco mosaic virus(TMV) in leaves of Nicotiana tabacum L. cv. Samsun has been studied. It was shown that the infectivity and viral coat protein content in leaves inoculated with a mixture of TMV(2 μg/mL) and chitosan(1 mg/mL) were lower in the early period of infection(3 days after inoculation), by 63% and 66% respectively, than in leaves inoculated with TMV only. Treatment of leaves with chitosan 24 h before inoculation with TMV also caused the antiviral effects, but these were less apparent than when the virus and polysaccharide were applied simultaneously. The inhibitory effects of the agent decreased as the infection progressed. Inoculation of leaves with TMV together with chitosan considerably enhanced the activity of hydrolases(proteases, RNases) in the leaves, in comparison with leaves inoculated with TMV alone. Electron microscope assays of phosphotungstic acid(PTA)-stained suspensions from infected tobacco leaves showed that, in addition to the normal TMV particles(18 nm in diameter, 300 nm long), these suspensions contained abnormal(swollen, "thin" and "short") virions. The highest number of abnormal virions was found in suspensions from leaves inoculated with a mixture of TMV and chitosan. Immuno-electron microscopy showed that "thin" virus particles, in contrast to the particles of normal diameter, lost the ability to bind to specific antiserum. It seems that the chitosan-induced activation of hydrolases stimulates the intracellular degradation of TMV particles and hence hydrolase activation may be considered to be one of the polysaccharide-mediated cellular defense mechanisms that limit virus accumulation in cells.     

Inhibitory effect of κ/β-carrageenan from red alga <Emphasis Type=Italic>Tichocarpus crinitus</Emphasis> on the development of a potato virus X infection in leaves of <Emphasis Type=Italic>Datura stramonium</Emphasis> L.

The effect of κ/β-carrageenan from red alda Tichocarpus crinitus on the development of a potato virus X (PVX) infection in the leaves of Datura stramonium L. has been studied. The treatment of leaves with carrageenan stimulates a protein synthesis in the cells, causing an increase in the size of nucleoli and in the number of mitochondria and membranes of the rough endoplasmic reticulum. At the same time, such treatment slightly stimulates lytic processes, causing an increase in the number of smooth endoplasmic reticulum cisternae, dictyosomes, and cytoplasmic vacuoles and the formation of cytoplasmic electron-transparent zones. The carrageenan-induced stimulation of lytic processes results in the destruction of viral particles and can be considered as one of the defense mechanisms, preventing the intracellular accumulation of virus. The carrageenan-stimulated formation of PVX-specific laminar structures, able to bind viral particles and, therefore, prevent their intracellular translocation and reproduction, represents another carrageenan-induced mechanism of the antiviral defense in plant cells.     

Effect of physical exercise on fibrinolytic properties of erythrocytes

The fibrinolytic properties of blood and erythrocytes were studied before and after physical exercise in male volunteers. Their fibrinolytic responses were of two distinct types. In type 1 response, fibrinolytic activities of blood and erythrocytes increased; the plasminogen activator and active plasmin contents in erythrocytes also increased, whereas the profibrinolysin content correspondingly decreased. In addition, physical exercise increased the erythrocyte adsorption properties for plasma activators of fibrinolysis. Type 2 response was characterized by a decrease in the fibrinolytic activity of blood; neither fibrinolytic activity nor adsorption properties of erythrocytes increased. The type of blood and erythrocyte response to muscular activity was determined by the pre-exercise level of red blood cell fibrinolytic activity. It was low in type 1 response due to a lesser content of plasmin activators and greater content of antiplasmin. In type 2 response, the initially high lytic capacity is connected with a greater reserve of activators and lesser reserve of inhibitors of the fibrinolytic system. A conclusion was made that individual differences in fibrinolytic responses to physical exercise were largely accounted for by the properties of erythrocytes.     

Antioxidative enzyme and glutathione S-transferase activities in diabetic rats exposed to long-term ASA treatment

Low-dose acetylsalicylic acid (ASA) treatment is a standard therapeutic approach in diabetes mellitus for prevention of long-term vascular complications. The aim of the present work was to investigate the effect of long-term ASA administration in experimental diabetes on activities of some liver enzymes: glutathione peroxidase (GSHPx), catalase, glucose-6-phosphate dehydrogenase (G6PDH) and glutathione S-transferase (GST). Blood glucose, glycated hemoglobin, as well as plasma ALT and AST activities increased in rats with streptozotocin-induced experimental diabetes. The long-term hyperglycemia resulted in decreased activities of GSHPx (by 26%), catalase (by 34%), GST (by 38%) and G6PDH (by 27%) in diabetic animals. We did not observe increased accumulation of membrane lipid peroxidation products or altered levels of reduced glutathione in livers. The linear correlation between blood glucose and glycated hemoglobin in diabetic animals was distorted upon ASA treatment, which was likely due to a chemical competition between nonenzymatic protein glycosylation and protein acetylation. The long-term ASA administration partially reversed the decrease in GSHPx activity, but did not influence the activities of catalase and GST in diabetic rats. Otherwise, some decrease in these parameters was noted in ASA-treated nondiabetic animals. Increased ASA-induced G6PDH activity was recorded in both diabetic and nondiabetic rats. While both glycation due to diabetic hyperglycemia and ASA-mediated acetylation had very similar effects on the activities of all studied enzymes but G6PDH, we conclude that non-enzymatic modification by either glucose or ASA may be a common mechanism of the observed convergence.     

Expression of Toll-like receptor 2 is up-regulated in monocytes from patients with chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is characterised by pulmonary and systemic inflammation which flare-up during episodes of acute exacerbation (AECOPD). Given the role of Toll-like receptors (TLRs) in the induction of inflammatory responses we investigated the involvement of TLRs in COPD pathogenesis.

Methods

The expression of TLR-2, TLR-4 and CD14 in monocytes was analyzed by flow cytometry. To study the functional responses of these receptors, monocytes were stimulated with peptidoglycan or lipopolysaccharide and the amounts of TNFα and IL-6 secreted were determined by ELISA.

Results

We found that the expression of TLR-2 was up-regulated in peripheral blood monocytes from COPD patients, either clinically stable or during AECOPD, as compared to never smokers or smokers with normal lung function. Upon stimulation with TLR-2 ligand monocytes from COPD patients secreted increased amounts of cytokines than similarly stimulated monocytes from never smokers and smokers. In contrast, the expressions of TLR-4 and CD14 were not significantly different between groups, and the response to lipopolysaccharide (a TLR-4 ligand) stimulation was not significantly different either. At discharge from hospital TLR-2 expression was down-regulated in peripheral blood monocytes from AECOPD patients. This could be due to the treatment with systemic steroids because, in vitro, steroids down-regulated TLR-2 expression in a dose-dependent manner. Finally, we demonstrated that IL-6, whose plasma levels are elevated in patients, up-regulated in vitro TLR-2 expression in monocytes from never smokers.

Conclusion

Our results reveal abnormalities in TLRs expression in COPD patients and highlight its potential relationship with systemic inflammation in these patients.