Mechanisms of oxidative modification of low density lipoproteins under conditions of oxidative and carbonyl stress

Low-molecular-weight aldehydes (glyoxal, methylglyoxal, 3-deoxyglucosone) generated on autooxidation of glucose under conditions of carbonyl stress react much more actively with amino groups of L-lysine and epsilon-amino groups of lysine residues of apoprotein B-100 in human blood plasma low density lipoproteins (LDL) than their structural analogs (malonic dialdehyde (MDA), 4-hydroxynonenal) resulting on free radical oxidation of lipids under conditions of oxidative stress. Glyoxal-modified LDL aggregate in the incubation medium with a significantly higher rate than LDL modified by MDA, and MDA-modified LDL are markedly more poorly absorbed by cultured human macrophages and significantly more slowly eliminated from the rat bloodstream upon intravenous injection. Studies on kinetics of free radical oxidation of rat liver membrane phospholipids have shown that ubiquinol Q(10) is the most active lipid-soluble natural antioxidant, and suppression of ubiquinol Q(10) biosynthesis by beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitors (statins) is accompanied by intensification of lipid peroxidation in rat liver biomembranes and in LDL of human blood plasma. Injection of ubiquinone Q(10) protects the human blood plasma LDL against oxidation and prevents oxidative stress-induced damages to rat myocardium. A unified molecular mechanism of atherogenic action of carbonyl-modified LDL in disorders of lipid and carbohydrate metabolism is discussed.     

Cassava leaf harvesting as vegetables; a cause of vulnerability of cassava plant to cassava mosaic disease and eventual yield reduction: Ernte von cassavablättern als gemüse; eine ursache für die anfälligkeit der cassavapflanze für die cassava-mosaikkrankheit und für spätere ertragseinbußen

The consequence of harvesting young leaves of cassava as vegetable on the vulnerability of the crop to cassava mosaic disease (CMD) and on storage root yield was investigated using 30 cassava genotypes planted in IITA fields located in the humid forest (Port Harcourt?:?Onne), forest-savannah transition (Ibadan), southern guinea savannah (Mokwa) and northern guinea savannah (Zaria) agroecologies in Nigeria. Tender apical leaves and shoots of the cassava genotypes were removed from forty plants per cassava genotype with the same number of plants considered as control. Whitefly infestation, disease incidence (DI) and symptom severity (ISS) of the disease were assessed at monthly interval for six months and also at the ninth month after planting (MAP). Yield reduction due to this treatment was calculated as percentage harvest index (HI). Whitefly population fluctuated throughout the period of observation at all locations with higher population obtained generally for treated plants compared to control plants. Sprouting leaves of some treated genotypes were observed with severe mosaic symptoms, while corresponding control showed no mosaic symptoms. Contrarily, no remarkable difference was observed in Zaria between the mean ISS of treated and control cassava genotypes. There was a highly significant difference (P?<?0.01) in DI and ISS among cassava genotypes across all locations. Also, there was a highly significant interaction (P?<?0.01) in symptom severity between location (loc) and genotype, genotype and treatment (trt), loc and trt. Interaction between loc, genotypes and trt with regard to DI was highly significant at 2, 3 and 4 MAP, while with ISS, the interaction was highly significant all through the counting period. There was a positive relationship between DI and ISS on plants of genotypes 96/1039 and ISU. The percentage HI (27.4) of treated plants of genotype 95/0166 in Ibadan was remarkably lower than the value obtained for corresponding control (41.9) plants. Also, sharp distinction in% HI of treated (39.5) and control (43.8) ISU was observed in Onne with their respective ISS values as 3.7 and 3.2. Therefore, harvesting tender apical leaves and shoots of cassava as vegetables should be discouraged as it increases the severity of CMD infection in the regenerating shoots of cassava with attendant storage root yield reduction.     

Intracellular development of Bdellovibrio bacteriovorus

The intracellular growth of Bdellovibrio bacteriovorus, a bacterial parasite, was studied by a light-optical method using time-lapse cinemicrography. The organism was found to be capable of growth in the periplasmic space of filamentous cells of the host bacterium Pseudomonas fluorescens without any contact with the cytoplasmic membrane. Several B. bacteriovorus cells could grow simultaneously in the bdelloplasm.     

Inhibition of functional activity of macrophages in vitro by dimer RNase Bacillus intermedius

The influence of cross-linked by dimethylsuberimidate dimeric RNAse from Bacillus intermedius on peritoneal rat macrophages has been investigated in vitro. It has been shown that dimeric RNase with concentrations of 0.5-40.0 mg/ml decreases the functional activities of macrophages. This is manifested in the inhibition of the phagocyte function of macrophages and suppression of the fusion of phagosomes with lysosomes. The change in the cytoplasmatic membrane surface structure induced by the dimers, which is stronger than that induced by monomers, has been demonstrated using atomic force microscopy. The role of membrane properties modification in the inhibition effect of RNase dimers on the functional activities of macrophages is discussed.     

Biocatalytic membranes for ultrafiltration treatment of wastewater containing dyes

A possibility to prepare the biofunctional membranes showing the biocatalytic properties and use those in post-treatment of wastewater containing synthetic dyes have been established. Selected Pseudomonas mendocina and Bacillus subtilis cultures were used as biocatalysts for dye destruction. It has been established that cells in spore form are able to survive in N-methylpyrrolidone that allow to use method of polymer solution casting for membrane preparation. The optimal conditions for entrapping of whole cells of microorganisms into the polymer matrix have been determined. Membrane biocatalytic activity has been studied depending on method of casting solution preparation, biocatalyst loading and operating parameters. Dye destruction occurs both in membrane pores and on membrane surface. Membrane obtained provide discolouring of treated solutions (permeate). The dye concentration in retentate depends on the trans-membrane fluxes. The concentration in retentate need not be observed at relatively low fluxes (up to 20 l/m² h).     

Fructose as an inducer of free radical peroxidation of natural lipid-protein supramolecular complexes

D-fructose strongly stimulates peroxidation of natural lipid-protein supramolecular complexes in vitro regardless of the oxidation initiation method. Fructose (ketose) intensifies free radical peroxidation to a much greater extent than glucose (aldose), which is important for the etiology and pathogenesis of diabetes mellitus.     

Antioxidants decreases the intensification of low density lipoprotein in vivo peroxidation during therapy with statins

The oxidative modification of low density lipoprotein (LDL) is thought to play an important role in atherogenesis. Drugs of -hydroxy--methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) family are usually used as a very effective lipid-lowering preparations but they simultaneously block biosynthesis of both cholesterol and ubiquinone Q₁₀ (coenzyme Q), which is an intermediate electron carrier in the mitochondrial respiratory chain. It is known that reduced form of ubiquinone Q₁₀ acts in the human LDL as very effective natural antioxidant. Daily per os administration of HMG-CoA reductase inhibitor simvastatin to rats for 30 day had no effect on high-energy phosphates (adenosin triphosphate, creatine phosphate) content in liver but decreased a level of these substances in myocardium. We study the Cu²⁺-mediated susceptibility of human LDL to oxidation and the levels of free radical products of LDL lipoperoxidation in LDL particles from patients with atherosclerosis after 3 months treatment with natural antioxidants vitamin E as well as during 6 months administration of HMG-CoA reductase inhibitors such as pravastatin and cerivastatin in monotherapy and in combination with natural antioxidant ubiquinone Q₁₀ or synthetic antioxidant probucol in a double-blind placebo-controlled trials. The 3 months of natural antioxidant vitamin E administration (400 mg daily) to patients did not increase the susceptibility of LDL to oxidation. On the other hand, synthetic antioxidant probucol during long-time period of treatment (3–6 months) in low-dose (250 mg daily) doesn't change the lipid metabolism parameters in the blood of patients but their high antioxidant activity was observed. Really, after oxidation of probucol-contained LDL by C-15 animal lipoxygenase in these particles we identified the electron spin resonance signal of probucol phenoxyl radical that suggests the interaction of LDL-associated probucol with lipid radicals in vivo. We observed that 6 months treatment of patients with pravastatine (40 mg daily) or cerivastatin (0.4 mg daily) was followed by sufficiently accumulation of LDL lipoperoxides in vivo. In contrast, the 6 months therapy with pravastatin in combination with ubiquinone Q₁₀ (60 mg daily) sharply decreased the LDL initial lipoperoxides level whereas during treatment with cerivastatin in combination with probucol (250 mg daily) the LDL lipoperoxides concentration was maintained on an invariable level. Therefore, antioxidants may be very effective in the prevention of atherogenic oxidative modification of LDL during HMG-CoA reductase inhibitors therapy.