Membrane effects of nitrite-induced oxidation of human red blood cells.

The aim of our investigation was to study the red blood cell (RBC) membrane effects of NaNO(2)-induced oxidative stress. Hyperpolarization of erythrocyte membranes and an increase in membrane rigidity have been shown as a result of RBC oxidation by sodium nitrite. These membrane changes preceded reduced glutathione depletion and were observed simultaneously with methemoglobin (metHb) formation. Changes of the glutathione pool (total and reduced glutathione, and mixed protein-glutathione disulfides) during nitrite-induced erythrocyte oxidation have been demonstrated. The rates of intracellular oxyhemoglobin and GSH oxidation highly increased as pH decreased in the range of 7.5-6.5. The activation energy of intracellular metHb formation obtained from the temperature dependence of the rate of HbO(2) oxidation in RBC was equal to 16.7+/-1.6 kJ/mol in comparison with 12.8+/-1.5 kJ/mol calculated for metHb formation in hemolysates. It was found that anion exchange protein (band 3 protein) of the erythrocyte membrane does not participate significantly in the transport of nitrite ions into the erythrocytes as band 3 inhibitors (DIDS, SITS) did not decrease the intracellular HbO(2) oxidation by extracellular nitrite.     

Effect of fucoidan on potato virus X accumulation and ultrastructure of mesophyll cells of Datura stramonium L.

The accumulation of potato virus X (PVX) in mesophyll cells of detached Datura stramonium L. leaves treated with fucoidan from brown algae Fucus evanescens C. Ag. have been evaluated by electron microscopy during the early infection period (three days after infection). It was found that cells of the leaves treated with fucoidan 24 h before infection accumulated virus less than untreated control. Ultrastructure-morphometric assay showed that fucoidan treatment causes an increase in the protein-synthesizing capability of cells (nucleolus dimention and amount of both mitochondria and rough endoplasmic reticulum membranes increased). At the same time, fucoidan treatment slightly activates the lytic compartment, which leads to the destruction of virus particles. Therefore, it may be considered that fucoidan induces a cellular defense mechanism that limits virus accumulation. Stimulation by the fucoidan of the formation of PVX-specific laminar structures able to bind virus particles may be another antiviral cell defense mechanism induced by the virus that prevents PVX reproduction and its intra- and intercellular transport.     

Imidazoles in the treatment of ocular mycoses

The use of a new class of broad spectrum antifungal drugs i.e. imidazoles and in particular ketoconazole in treatment of severe affections of the eye such as mycoses is described. The clinical trials included 40 patients with various forms of mycosis: mycotic canaliculitis (6 patients), mycotic blepharitis (4 patients), mycotic conjunctivitis (7 patients), keratomycosis (17 patients) and mycotic endophthalmitis (6 patients). Ketoconazole was used in the form of tablets and instillations. The combined treatment included nonsteroid antiinflammatory drugs and antibacterial agents. The clinical trials showed that ketoconazole had pronounced antifungal activity and was rather efficient in treatment of ocular mycoses. Its broad spectrum and low toxicity were recorded.     

Effect of sex and age on structural features of nasal calls and body size in fawns of the goitered gazelle, <Emphasis Type="Italic">Gazella subgutturosa</Emphasis> (Artiodactyla,Bovidae)

Male goitered gazelles differ from conspecific females in having a highly prominent larynx. However, the development of sex dimorphism in the vocal apparatus and the structure of calls has not yet been studied in this species. This study deals with structural changes in the acoustic parameters of nasal calls and the body size of goitered gazelle fawns in the course of ontogeny, from birth to 6 months of age. It has been shown that their body weight and neck girth linearly increase with age, while the basic frequency of nasal calls decreases gradually; however, age-related changes in the duration and power parameters of nasal calls are nonlinear. Their basic frequency (94 Hz in males and 118 Hz in females at the age of 2 weeks) is significantly lower than in juveniles of any other ungulate species of comparable size. In fawns of any age group, the index of sexual dimorphism in the basic frequency of nasal calls is at least twice that in the body weight or neck girth, indicating that laryngeal hypertrophy in males is already developed at birth. On the other hand, this index does not increase until the fawns are 6 months old, which is evidence that the accelerated growth of male larynx apparently starts later, in the pubertal period, under the effect of sex hormones.     

Oxygen-related processes in red blood cells exposed to tert-butyl hydroperoxide

The correlation between the oxidative processes in tert-butyl hydroperoxide (tBHP)-exposed red blood cells and the reactions of oxygen consumption and release were investigated. Red blood cell exposure to tBHP resulted in transient oxygen release followed by oxygen consumption. The oxygen release in red blood cells was associated with intracellular oxyhaemoglobin oxidation. The oxygen consumption proceeded in parallel with free radical generation, as registered by chemiluminescence, but not to membrane lipid peroxidation. The oxygen consumption was also observed in membrane-free haemolyzates. The order of the organic hydroperoxide-induced reaction of oxygen release with respect to the oxidant (tBHP) was estimated to be 0.9 +/- 0.1 and that of the oxygen consumption reaction was determined to be 2.4 +/- 0.2. The apparent activation energy values of the oxygen release and oxygen consumption were found to be 107.5 +/- 18.5 kJ/mol and 71.0 +/- 12.5 kJ/mol, respectively. The apparent pKa value for the functional group(s) regulating the cellular oxyHb interaction with the oxidant in tBHP-treated red blood cells was estimated to be 6.7 +/- 0.2 and corresponded to that of distal histidine protonation in haemoprotein. A strong dependence of tBHP-induced lipid peroxidation on the oxygen concentration in a red blood cell suspension was observed (P50 = 32 +/- 3 mmHg). This dependence correlated with the oxygen dissociation curve of cellular haemoglobin. The order of the membrane lipid peroxidation reaction with respect to oxygen was found to be 0.5 +/- 0.1. We can conclude that the intensity of the biochemical process of membrane lipid peroxidation in tBHP-exposed erythrocytes is controlled by small changes in such physiological parameters as the oxygen pressure and oxygen affinity of cellular haemoglobin. Neither GSH nor oxyhaemoglobin oxidation depended on oxygen pressure.     

Effect of cyclopentene ��,�¡�-triketone disodium salt on the activity of hydrolases and the state of tobacco mosaic virus particles in tobacco leaves

The activity of hydrolases (protease, RNase) in uninfected and tobacco mosaic virus-infected tobacco leaves of the Samsun variety, untreated and treated with disodium salt of 2-acetyl-4-hydroxycarbonyl-methylthio-5-chlorocyclopent-4-en-1,3-dione (DS), was determined. It was shown that treatment of leaves with this compound significantly increased the activity of hydrolases in them compared to untreated leaves. In infected leaves treated with DS one day before infection, along with an increased level of hydrolases, one revealed more viral particles exposed to destructive changes in infected, rather than untreated, leaves. It is assumed that the DS-caused activation of hydrolases promotes the destruction of viral particles and is therefore one of the cell defense mechanisms induced by this compound that prevents the intracellular accumulation of virus.     

Enzymatic transformation of biologically active 1,3;1,6-β-D-glucan. Structure and activity of resulting fragments

The fragmentation of the biologically active 1,3;1,6-beta-D-glucan Antivir by endo-1,3-beta-D-glucanase LIV from crystalline styles of the marine mollusk Spisula sachalinensis was carried out. It was found that low molecular mass oligomers possessing a stabilizing effect on membranes and anti-viral activity against tobacco mosaic virus appeared in the process of enzymatic hydrolysis of Antivir. Biological activity of 1,3;1,6-beta-D-glucooligo- and polysaccharides was found to be associated with molecular mass (polymerization degree (n) not less than 14) and with presence of intralinked beta-1,6-connected monosaccharide residues. Probably, decrease in molecular mass is compensated by increase in number of intralinked beta-1,6-connected monosaccharide residues.     

Influence of culture conditions and virulence plasmids on expression of immunoglobulin-binding proteins of Yersinia pseudotuberculosis

The influence of culture conditions and plasmids on immunoglobulin (Ig)-binding activity of two isogenic strains of Yersinia pseudotuberculosis (plasmid-free strain 48(-)82(-) and strain 48(+)82(+) bearing plasmids pYV48 and pVM82) was studied. The highest activity was observed in the bacteria grown on glucose-containing liquid medium in the stationary growth phase. The Ig-binding activity of the bacteria cultured on the liquid medium at pH 6.0 was about 1.5-fold higher than that of the bacteria grown at pH 7.2. Expression of the Ig-binding proteins (IBPs) was most influenced by temperature of cultivation. The IBP biosynthesis was activated in the bacteria grown at 4 degrees C and markedly decreased in those grown at 37 degrees C. The Ig-binding activity of lysates from the bacteria was caused by proteins with molecular weights of 7-20 kD. The activities of the plasmid-free and plasmid-bearing Y. pseudotuberculosis strains (48(-)82(-) and 48(+)82(+), respectively) were analyzed, and the plasmids were shown to have no effect on the IBP expression and biosynthesis, which seemed to be determined by chromosomal genes.     

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.     

The Condition of Ovaries in Hatchery-Reared Juvenile Summer- and Fall-Run Chum Salmon, <Emphasis Type="Italic">Oncorhynchus keta</Emphasis> (Walbaum, 1792), in Sakhalin Oblast

The condition of the ovaries in juvenile fall- and summer-run chum salmon prior to release was studied at five fish hatcheries that operate on Sakhalin Island. It has been found that juveniles released from different hatcheries, while having a similar body weight, may differ in the degree of development of their ovaries. Juvenile summer-run chum salmon showed a lower oogenesis rate at the hatchery with the warmest water and a higher oogenesis rate at the relatively cold-water hatcheries, compared to that of fall-run juveniles.