[Quantitative characteristic of the redox state of erythrocytes]

The introduction of the parameters characterizing the redox state of the cell, such as the effective redox potential and the redox buffer capacity has been theoretically substantiated. A comparative study of the parameters of the redox state of erythrocytes from healthy donors and patients with diabetes and acute coronary syndrome has been performed. It was found that the redox buffer capacity in erythrocytes from patients with diabetes and acute coronary syndrome was reduced by 30-40% in comparison with the redox buffer capacity of erythrocytes from healthy donors. The largest change in the effective redox potential was observed for erythrocytes from patients with diabetes, which indicates a more expressed oxidative stress in this pathology.

[Redox-homeostasis of cells]

Recent achievements of biophysics and physiology resulted to remarkable progress in the understanding of role of redox processes in cell vital function. It was established that oxidizing and reducing agents participate in processes of differentiation, proliferation and apoptosis. Representations about an existence of definite balance between oxidation and reduction processes in cells or a redox homeostasis were formed. Recent data about mechanisms of regulation of redox homeostasis were considered in the review. The correlation between redox homeostasis and metabolism were in detail analyzed. The special interest is given to a problem of quantitative description of redox phenomena in biological systems.

[The formation of stable aggrregates of human platelets induced by lectin from Solanum tuberosum]

It has been demonstrated for the first time that GlcNAc-specific lectin from Solanum tuberosum induces the formation of haptenic sugar-resistant intercellular contacts (HSR-contacts) in platelet aggregation and does not induce stable neutrophil and lymphocyte aggregation. The formation of HSR-contacts in platelets was significantly impaired by the inhibitors of cAMP phosphodiesterase (papaverine) and arachidonic acid methabolism (indomethacin, aristolochic acid, and MK-886) as well as by the sulfhydryl reagent N-ethylmaleimide. The results obtained indicate that STA can be used to study the mechanisms of stable platelet aggregation, to screen drugs with potential antithrombotic activity, and to develop new cell engineering techniques.

[Effect of hydrogen peroxide on ability of neutrophils to generate the reactive oxygen and chlorine species and secrete myeloperoxidase in vitro]

The influence of H2O2 at concentrations of 10(-8)--10(-2) mol/l on neutrophil ability to generate the reactive oxygen and chlorine species (ROCS) and secrete myeloperoxidase (MPO) was studied, and H202 injurious effect on neutrophils was also investigated in this work. It was revealed that H2O2 at concentrations of 2 x 10(-3)--2 x 10(-2) mol/l induced disturbance of the neutrophil membrane barrier properties and lactate dehydrogenase release. The incubation of the neutrophils with the addition of 10(-4)--10(-7) mol/l H2O2 led to an increase in the cell ability to generate ROCS during phagocytosis and decreased neutrophil ability to secrete MPO and ROCS in extracellular medium during adhesion. The mechanisms of H2O2 effect are coupled with arachidonic acid metabolism. Inhibition of metabolic pathways of 5-lipoxygenase or cyclooxygenase increased the destructive effect of H2O2 on the cells. Five-lipoxygenase way prohibition led to cancellation of H2O2 influence on MPO and ROCS secretion and to enhancement of H2O2 effect on neutrophil ability to generate ROCS during phagocytosis. The data obtained testify to the high neutrophil resistance to destructive effect of H2O2 and confirm the regulatory role of H2O2 with respect to the neutrophil functions.

Effects of peroxynitrite and lipopolysaccharide on mitotic activity of C6 glioma cells

Peroxynitrite is one of the most potent neurotoxic agents with multiple targets in neurons and glial cells. This study addressed a question of whether peroxynitrite-mediated cytotoxicity can be prevented by Escherichia coli lypopolisaccharide (LPS) due to its mitogenic activity towards C6 glioma cells. A number of characteristic morphological changes (processes impairments, nuclei modifications, cytoplasm vacuolization) and apoptotic cells were observed in the cell culture after 24-h treatment with 3-morpholinosyndnonimine (SIN-1), a well-known donor of peroxynitrite. These morphological changes were clearly associated with a SIN-1 dose-dependent increase in the number of pathological mitoses as well as with SIN-1 inhibition of the menadione-induced, lucigenin-enhanced chemiluminescence of C6 glioma cells, an independent indicator of mitotic activity of these cells. The mitotic index of C6 glioma cells increased in response to LPS and underwent non-uniform changes depending on SIN-1 concentrations. At a mitogenic concentration of 100 ng/ml, LPS reduced significantly the toxicity of SIN-1 determined as the accumulation of pathological mitoses, thus acting as a protective agent. Taken together, our findings indicate that SIN-1 specifically impairs the mitotic process in C6 glioma cells, and provide the first evidence that antimitotic effects of peroxynitrite can be restored by LPS.

[Regulation of morphologicaland functional properties of astroglial cells by hydrogen peroxide]

Effects of hydrogen peroxide on morphological characteristics, proliferation index, menadione-dependent lucigenin-enhanced chemiluminescence of C6 glioma cells were studied. It was established that H2O2 at 1 x 10(-8) - 5 x 10(-7) M concentrations acts as a regulator of morphological and functional properties of astrocytes by inducing their reactivation that is manifested as a cell body hypertrophy and an increase of proliferative activity and of menadione-dependent production of superoxide (O2- ). Cytodestructive action of hydrogen peroxide at a concentration higher than 1 microM on C6 glioma cells shows itself as a decrease of their proliferation index and the ability to generate O2- under menadione action. Using lipopolysaccharide B as a functional stimulator it has been shown that H2O2 modifies signaling pathways leading to the increase of mitotic activity of C6 glioma cells and decreases the yield of lucigenin-enhanced chemiluminescence of astrocytes under menadione action to the level of control values.

[Formation of reactive oxygen species in monocytes at adhesion to glass]

Processes of oxygen activation in monocytes stimulated with adhesion to glass were studied by methods of luminol-dependent and lucigen-independent chemiluminescence. It was shown that monocyte chemiluminescence was caused by cell adhesion to glass surface. Generation of reactive oxygen species at monocyte adhesion to glass was dependent on calcium ion concentration in the medium. The increase in the level of cytosolic calcium, as the extracellular calcium concentration elevated, was accompanied by the activation of phospholipase A2, 5-lypoxygenase and cycloxygenases. Magnesium ions exerted no influence on oxygen activation by cells. Incubation of cells in glucose-free medium, or the addition of glycolysis blocker (2-deoxy-D-glucose) to cell suspension led to a decrease in chemiluminescence intensity. By means of inhibitory analysis, it has been established that processes of oxygen activation are related to arachidonic acid metabolism, and depend on the activity of phospholipase A2.

[Consumption of intracellular hydrogen peroxide in epithelial human amnion cells]

The method for determination of intracellular oxidants content has been proposed. The method is based on the analysis of changes of 2,7-dichlorodihydrofluorescein oxidation. The theoretical model of hydrogen peroxide diffusion and its consumption in the cell and quantitative determination of hydrogen peroxide gradient through the cellular membrane has been built taking into account the experimental data. The coefficient for H2O2 permeability through the plasma membrane of human amnion cells is (2.1 +/- 0.1) x 10(-4) cm x c(-1).

Intracellular redox state: towards quantitative description

Redox state is a widely used term for the description of redox phenomena in biological systems. The regulating mechanisms responsible for maintaining the redox state are not yet fully known. But it was shown that changes in the redox state might lead to a cascade of intracellular events, beneficial or deleterious to the cell. There are several methods for the description of the intracellular redox state. These methods are based on using measured intracellular concentrations of reduced and oxidized glutathione in the Nernst equation. However, glutathione is not always a basic redox component in biological fluids, organelles, cells or tissues. As a result, changes in the intracellular redox state are not always accompanied by considerable changes of glutathione concentration. In this work it was proposed to use the concept of effective reduction potential for the quantitative characteristic of the intracellular redox state. The effective reduction potential was substantiated on the basis of a thermodynamic description. A new equation for the calculation of the effective reduction potential was derived. This equation summarizes the contribution of different oxidizing and reducing agents in the formation of an effective redox potential. The theoretical estimation of the effective reduction potential values for the different biological fluids and cells was carried out with the use of a method developed.

Influence of neopterin on the generation of reactive oxygen species in human neutrophils

Neopterin is synthesized by human monocyte-derived macrophages primarily upon stimulation with the cytokine interferon-gamma. We studied the influence of neopterin on the generation of reactive oxygen species (ROS) in human peripheral blood neutrophils. Radical formation was measured using a biochemiluminometer. Neutrophils were isolated from peripheral blood of healthy donors. The generation of ROS by neutrophils suspended in Earl's solution (pH=7.4) at 37 degrees C was investigated by monitoring of chemiluminescence using luminol and lucigenin as light emitters. Neopterin induced chemiluminescence in suspensions of neutrophils in the presence of luminol, but not of lucigenin. Neopterin affected only adhesive cells. Addition of neopterin into the suspension of the cells involving D-mannitol, L-histidine and diazabicyclo[2.2.2]octane (DABCO) decreased luminol-dependent chemiluminescence (LDCL) of the neutrophils. The action of superoxide dismutase (SOD) and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) reduced neopterin-induced LDCL of neutrophils. Data suggest that neutrophils respond on exposure to neopterin with additional generation of singlet oxygen, hydroxyl radical and nitric oxide by nicotinamide adenine dinucleotide phosphate (NADPH)-independent pathways.

[Regulation of the neurite growth]

Recent achievement of molecular biology and neurophysiology resulting in remarkable progress in the understanding of processes of neurodifferentiation, playing the relevant role both in an ontogenesis and working of adult brain. New representations have been formed about a role of cytoskeletal proteins in mechanisms of neurites growth. In the review we discussed recent data regarding mechanisms of neuronal differentiation regulation. The special interest is given to a problem of influence of electrical fields on neuronal growth and differentiation. The mechanisms of signal transduction from a cell surface to nuclear are in detail analyzed. The classification of the physical and chemical factors of growth neurites regulation is given.

[Damage to erythrocytes caused by the interaction of nitrite-ions with hemoglobin]

The formation of two hemoglobin forms (methemoglobin and nitrite methemoglobin) in native human erythrocytes in the presence of sodium nitrite in suspension was shown. In normal erythrocytes, the interaction of intracellular oxyhemoglobin with nitrite ions results in the formation of methemoglobin, whereas in metabolically exhausted erythrocytes, this leads predominantly to the formation of nitrite methemoglobin. The nitrite methemoglobin reacts with hydrogen peroxide to form reactive intermediates (e.g. peroxynitrous acid) and the products of hemoglobin destruction. During the storage of erythrocyte suspensions containing methemoglobin and modified nitrite methemoglobin, differences in the forms of erythrocytes and the degree of their hemolysis were revealed. It is assumed that the formation of methemoglobin leads to the destruction of erythrocytes.

Differential potency of two crosslinking plant lectins to induce formation of haptenic-sugar-resistant aggregates of rat thymocytes by post-binding signaling

To evaluate the significance of post-binding events for stable aggregate formation, the aggregation/dissociation of rat thymocytes initiated by two crosslinking plant lectins, namely concanavalin A (Con A) and Solanum tuberosum agglutinin (STA), were comparatively studied. Despite intimate cell contacts in the aggregates only Con A led to establishment of haptenic-sugar-resistant (HSR) complexes. The presence of inhibitor II of diacylglycerol kinase, a dual calmodulin antagonist/protein kinase C inhibitor (trifluoperazine), and a sulfhydryl group reagent (N-ethylmaleimide) impaired this process. The obtained results indicate that the formation of HSR cellular contacts is not an automatic response to lectin-dependent cell association. In contrast to STA, Con A binding elicits this reaction with involvement of diacylglycerol kinase, protein kinase C and/or calmodulin as well as thiol level perturbation, as inferred by the application of target-selective inhibitors.

[Lectin-reactive immune complexes in plasma in ENT diseases]

The content of circulating immune complexes (IC) interacting with plant lectins from Canavalia ensiformis (Con A), phaseolus vulgaris (PHA) and wheat germ (WGA) was examined in blood plasma of healthy donors and patients with ENT diseases (n = 36). It was found that the level of PHA- and WGA-reactive IC in patients with laryngeal carcinoma was significantly higher than in control, whereas only the level of WGA-reactive IC was elevated in patients with scleroma. The level of ConA-reactive IC was statistically uniform in control and both ENT diseases.

[Relationship between the oxidation-reduction system of astrocytes with production of active forms of oxygen]

Cells of neuroglia--the astrocytes are of interest from the point of view of their participation in phagocytosis. Phagocyte ability to generate active oxygen forms (AOF) as used as the basic criterion of the estimation of their functional activity. For the purpose to clear up molecular and cellular mechanisms of phagocytosis a study of astrocyte redox-systems, participating in production of AOF, was undertaken. Registration of AOF in astrocytes was carried out using a method of luminol-dependent chemiluminescence. Primary culture of guinea pig astrocytes was used. Spontaneous chemiluminescence of low intensity was found for the astrocytes at the presence of luminol. The destruction of the cells was accompanied by a significant growth of the intensity of spontaneous chemiluminescence. Suspension of endocutosis inductors, particle of latex and phytohemagglutinin, added to astrocytes did not result in formation of AOF, characteristic for other cells, possessing phagocytosis. It was established, that addition of hydrogen peroxide destroys astrocytes at the presence of luminol and gives rise to the emission. Chemiluminescence was not observed in similar experiments with intact cells. A conclusion was made that inside astrocytes there are structures, which show peroxidase-like activity.

Metabolic inhibitors as tools to delineate participation of distinct intracellular pathways in enhancement of lactose-induced dissociation of neutrophil and thymocyte aggregates formed by mediation of a plant lectin

Signaling processes in the course of the formation of the lectin-mediated aggregates may partake in conveying enhanced stability to the cell clusters. To prove the validity of this reasoning in a model, we have studied the impact of addition of three metabolic inhibitors (N-ethylmaleimide, nordihydroguaiaretic acid, and trifluoperazine) on lactose-dependent dissociation of cell aggregates, formed in the presence of the galactoside-binding mistletoe lectin. Using both human neutrophils and rat thymocytes to avoid measurement of responses restricted to a single cell type, an enhanced dissociation of lectin-formed cell aggregates was observed, when lactose and an inhibitor were present. Among the tested inhibitors, nordihydroguaiaretic acid and N-ethylmaleimide were more potent enhancers of cell dissociation than trifluoperazine. These results suggest that biosignalling pathways connected with lipoxygenase activity as well as the level of intracellular sulfhydryl groups confer further stability to lectin-dependent cell aggregates. The systematic evaluation of inhibitors for defined activities is thus suggested as a tool to disclose the nature and the contribution of individual signaling mechanisms to post-binding effects following lectin-initiated cell contact formation.

Effects of metabolic inhibitors and lectins on the menadione-dependent generation of H2O2 by rat thymocytes

The capacity of oxidative metabolism and its regulation is an important factor in disease control. Using scopoletin as a fluorescent substrate of peroxidase the extent of menadione-dependent production of H2O2 by rat thymocytes was determined. The reaction was inhibited by 2,4-dinitrophenol, papaverine, nordihydroguaiaretic acid and iodacetamide. The membrane-penetrating SH reagent N-ethylmaleimide primed the reaction, probably due to an inhibition of glutathione peroxidase. To delineate an influence of cell-surface protein-carbohydrate interactions by exogenous lectins, the impact of cell binding was analyzed for several plant lectins, namely concanavalin A, phytohemagglutinin, the lectins from Triticum vulgaris and from Sambucus nigra. Except for the alpha-NeuNAc(2-6)gal/galNAc-binding agglutinin, the other three plant proteins with specificities to different parts of N-linked oligosaccharides primed the reaction. This activity of lectins did not coincide with their ability to aggregate cells. The given results indicate that biosignaling pathways triggered by lectins are involved in the regulation of the intracellular reduction of menadione.

[H2O2 generation and human neutrophil aggregation as affected by lectins]

The effects of eight plant lectins on human neutrophils aggregation and H2O2 release were studied. Both processes were stimulated by lectins from Viscum album, Triticum vulgaris, Phaseolus vulgaris and Canavalia ensiformis while lectins from Solanum tuberosum, Sambucus nigra and Glycine mas displayed only aggregating activity and Arachis hypogaea lectin was not effective. Heating (46 degrees C) and UV-radiation during 4-5 min were found to suppress completely H2O2 release from neutrophils keeping the capacity of cells to be aggregated. The findings indicate that lectin-induced human neutrophils aggregation is necessary but not sufficient condition of respiratory burst of cells. The comparison of the aggregating activity of lectins with their ability to induce the H2O2 release is supposed to be the basis of screening of lectins with antitumor and immunomodulatory activity.

Viscum album agglutinin-induced aggregation of blood cells and the lectin effects on neutrophil function

Extracts from mistletoe enjoy a large popularity in central Europe as an unconventional treatment modality for cancer, warranting scientific efforts with defined components to delineate any potential benefit. The galactose-specific lectin from Viscum album (VAA), known to exhibit immunomodulatory and ensuing antitumoral capacities in animal model systems, was shown to aggregate human blood cells in the following order: neutrophils, mononuclear cells--thrombocytes and erythrocytes. To contribute to the analysis of lectin effects on individual aspects of the host defence system, two parameters of neutrophils were quantitatively assessed, namely the aggregating activity of VAA as a measure of strength of interaction with cell surface ligands and the effect of lectin on oxidative metabolism (H2O2 release) of these cells. It was found that whole lectin and its carbohydrate-binding B-subunit possessed the capacity to induce cell aggregation and H2O2 release, which were blocked by D-galactose and lactose. Both effects displayed similar dependence on the lectin concentration in the range 0.1-25 micrograms/ml. The toxic A-subunit displayed detectable activity only in high doses (50 micrograms/ml) while the bovine heart galaptin (14 kDa; galectin-1) failed to affect neutrophils. The role of oxidative metabolism in regulation of neutrophil aggregation induced by VAA was studied using metabolic inhibitors and controlled heating at 46 degrees C leading to inhibition of plasma membrane NADPH-oxidase system. Trifluoperazine and menadione inhibited the neutrophil aggregation in a dose-dependent manner in comparison with such inhibitors as amiloride and theophylline.(ABSTRACT TRUNCATED AT 250 WORDS)

[The effect of hyperthermia (45 C) on lymphoid cell aggregation]

Hyperthermia (45 degrees C) has found to decrease the rate of rat thymocytes as well as splenocytes aggregation induced by lectins (concanavalin A, wheat germ agglutinin) and sulphated polysaccharides (heparin, dextran sulphate-500) and to increase those induced by cationic dye alcian blue. Shedding of plasma membrane glycoproteins and changes of surface charge are supposed to affect the aggregation.

[Aggregation of neutrophils and their generation of active forms of oxygen as affected by lectins]

It was shown that neutrophil aggregation is caused by all lectins with different specificity for carbohydrates but generation of active oxygen forms is induced only by some lectins. Polyspecific lectins-erythroagglutinin and phytohemagglutinins have the greatest activity in relation to both processes.

[The effect of metabolic inhibitors on resistance of mannose-specific contacts of Escherichia coli K12 and human neutrophils]

Human neutrophil aggregation induced by Escherichia coli K12 cells has been studied. D-mannose has been found to inhibit the process in the dose-dependent way causing the full blockage at 10 mM concentration. The process of disaggregation induced by the concentration is significantly higher at 10 degrees C than at 37 degrees C. The inhibitors of cellular oxygenation such as N-ethylmaleimide, nordihydroguaiaretic acid, trifluoperazine, and colchicine did not affect the aggregation process. Cellular aggregation was concomitant with production of H2O2, and this reaction was also blocked by D-mannose and depended on the number of bacteria present. The nordihydroguaiaretic acid and N-ethylmaleimide inhibited production of H2O2, while sodium azide enhanced the process. The results show the mannose-specific contact of bacteria and neutrophils to depend on the functional activity of phagocytes including their ability to produce H2O2.

[The effect of recombinant interleukin-1 beta on concanavalin A-induced lymphocyte reactions]

As revealed by investigations made by the use of the method of luminol-dependent chemiluminescence and light dispersion, the addition of concanavalin A (ConA) to the suspension of human peripheral blood lymphocytes and subsequent incubation with recombinant interleukin-1 beta leads to a sharp increase in the yield of chemiluminescence and the rate of cell aggregation in comparison with similar parameters obtained for cells, not treated with interleukin-1 beta. The study revealed the potentiating action of recombinant interleukin-1 beta on ConA-induced proliferative response of thymocytes in the culture. The mechanisms of the priming action of recombinant interleukin-1 beta on ConA-induced reaction of lymphocytes are discussed.

[The free-radical mechanisms of the cytotoxic action of 1,2-benzoquinone derivatives]

The authors examined the interaction of 1,2-benzoquinone derivatives with HeLa cell cultures and ascite Ehrlich's cancer cells. 4-N (anilino)-5-methoxy-1,2-benzoquinone was found to produce a marked toxic effects against tumor cells. The cytotoxic effect is oxygen dependent and associated with the formation of oxygen radicals in quinone's redox cyclization reactions. The inhibitory analysis was used to show that the major mediators of the toxic action of the agent are superoxide radical-anion and hydrogen peroxide. It is concluded that the interaction of highly toxic oxygen radicals, which are generated in quinone redox cyclization, with plasma membrane cells is likely to be the mechanism responsible for cellular destruction when quinones act on tumor cells.

[A comparative study of the reactions of the peripheral blood neutrophils from donors and from lymphogranulomatosis patients to arachidonate stimulation of the cells]

Arachidonate-induced aggregation and generalization of active oxygen forms (OAF) by peripheral blood neutrophils in donors were studied in donors and Hodgkin's disease patients. Leukocytes of the latter had incomplete ability to produce AOF in response to cell stimulation with arachidonic acid. The study of arachidonate-induced aggregation of neutrophils indicated no differences in the speed of the process in the patients and donors. AOF catchers did not act on the rate of leukocyte aggregation in the patients though accelerated the process in the donors. It is inferred that Hodgkin's disease is associated with dysfunction of oxygen activation by neutrophils. The findings suggest that defects in leukocytes ability to activate oxygen in Hodgkin's disease may entail deranged regulation of other processes essential for functional activity of polymorphonuclear leukocytes.