Preparation and Properties of Complexes Based on Chitosan-Ag Nanocomposite and Cephalosporin Antibiotics

Applied Biochemistry and Microbiology - Aggregatively stable, positively charged (~45 mV) chitosan-Ag nanocomposites with a spherical shape and size up to 60.0 nm were synthesized by the...     

Mutual influence of plasma membrane structures and intracellular calcium stores on the formation of calcium signals in primary nociceptive neurons

Participation of different calcium-regulating mechanisms in the formation of intracellular calcium signals in rat primary sensory neurons was studied using two-wavelength fluorescent microscopy. Mitochondria were shown to be the most powerful intracellular calcium-regulating structures in the investigated neurons. These organelles were involved in the modulation of calcium signals induced either by Ca²⁺ entry from the extracellular medium or by Ca²⁺ release from endoplasmic reticulum (ER). Analysis of the mitochondrial calcium exchange showed that the efficiency of mitochondria depended on whether calcium entered the cytosol from ER or from the extracellular solution. Depletion of ER by activation of ryanodine-sensitive, inositol-3-phosphate-sensitive receptors of ER or by activation of the leak channels via the block of ATPases in ER activated the store-operated calcium entry from the extracellular medium to cytosol. The kinetics of the rising phase of these Ca²⁺ transients depended on the way of ER depletion. This allows suggesting the existence of different activation mechanisms for the studied signals. The block of the mitochondrial calcium uniporter resulted in a rapid recovery of the intracellular calcium concentration after the Ca²⁺ transient induced by store-operated calcium influx. We conclude that mitochondrial calcium uptake can prevent calcium-dependent inactivation of store-operated calcium channels.     

Antiangiogenic and antivascular effects of a recombinant tumstatin-derived peptide in a corneal neovascularization model

Tumstatin, a cleavage fragment of collagen IV, is a potent endogenous inhibitor of angiogenesis. Tumstatin-derived peptide T8 possesses all angiostatic properties of full-length tumstatin and indirectly suppresses tumor growth. The potential of T8 to block pathological angiogenesis in the eye has not been explored yet. Here we assess antiangiogenic effects of a recombinant T8 peptide in rabbit corneal neovascularization models. The fusion protein consisting of T8 and thioredoxin was synthesized in a highly efficient Escherichia coli expression system, isolated using ion-exchange chromatography and cleaved with TEV (tobacco etch virus) protease. The target peptide was purified on an anion-exchange resin and by reversed phase high-performance liquid chromatography. The recombinant peptide suppressed the proliferation of basic fibroblast growth factor-induced SVEC-4-10 endothelial cells (simian virus 40-immortalized murine endothelial cells) and inhibited tube formation in these cells in a dose-dependent manner. In rabbit corneal neovascularization models T8 demonstrated the ability to prevent pathological angiogenesis (when injected simultaneously with the induction of neovascularization) and, moreover, to promote the regression of newly-formed blood vessels (when injected on day 8 after angiogenesis stimulation). Our results suggest that T8 may have a therapeutic potential in the treatment of ocular neovascular diseases.     

Development of a novel enzyme-redox-mediator system based on a fungal laccase and ruthenium complexes

The laccase produced by the fungus Coriolus hirsutus has been coordinatively modified with ruthenium complexes [Ru(phpy)(phen)(MeCN)₂]PF₆ and Ru(bpy)₂CO₃ under aerobic and anaerobic conditions. The amount of the complexes per enzyme molecule does not depend on the oxygen concentration, equaling 5 for [Ru(phpy)(phen)(MeCN)₂]PF₆ and 3 for Ru(bpy)₂CO₃. The pH dependence of the enzymatic activity, thermostability, and catalytical and electrocatalytical properties of the modified laccase are reported. It has been shown that, during the modification, at least one molecule of the ruthenium compound was coordinated near the T1 active center of the laccase, being directly involved in the catalysis and enhancing its efficiency.     

Comparison of the efficiency of polygalacturonase and β-glucosidase enzyme preparations in stabilization of cherry plum wine material

Pektofoetidin and Pectinex, enzyme preparations with the highest polygalacturonase and β-glucosidase activities, were covalently immobilized on DEAE cellulose and Aminosilochromes 10 and 30. After treatment of cherry plum wine material with the soluble and immobilized enzyme preparations, the content of phenolics increased by 26 and 40%, respectively. The increase was accompanied by a decrease in the protein content (by up to 37%), carbohydrate content (by 17% on the average), and antioxidant activity (5–37%). The most efficient treatment involved Pektofoetidin immobilized on Aminosilochrome 10. It increased the clarity of the wine material and its antioxidant activity by 100 and 10%, respectively.     

Content of myosin-activating protein kinases in myocardium of patients with dilated cardiomyopathy and in the animal heart

The skeletal myosin light chain kinase (skMLCK) was identified in human and chicken embryo myocardium but not in embryo and adult rat heart using western blotting. The content of skMLCK and myosin-activating protein kinases: RhaA-activated protein kinase (ROCK), integrin-linked protein kinase (ILK), and zipper-interacting protein kinase (ZIPK) was compared in normal human myocardium and the hearts of patients with dilated cardiomyopathy (DCM). It was demonstrated that the content of skMLCK, ROCK and ILK increases in DCM whereas the content of ZIPK decreases. The results obtained may reflect compensatory processes in cardiomyocytes in DMC, which are aimed at increasing their viability and contractility.     

Increase of the detoxification potential of basidiomycetes by induction of laccase biosynthesis

The effect of oxidoreductase inducers guaiacol and syringaldazine on the ability of Coriolus hirsutus, Coriolopsis fulvocinerea, Cerrena maxima, and cocultivated Coriolus hirsutus/Cerrena maxima to degrade atrazine in submerged cultures was studied. All the basidiomycetes reduced atrazine concentration with and without syringaldazine or guaiacol. The degree of atrazine degradation was higher in induced cultures (77-98% vs. 68-94% without induction). Of the four cultures, the highest detoxifying potential was observed in Coriolopsis fulvocinerea with and without an inducer (98% with guaiacol), and the lowest was in Cerrena maxima. Inducers decreased the residual atrazine concentration differently in the different cultures. A long-term increase of laccase production was observed in both induced and uninduced cultures, whereas the activity of Mn-peroxidase decreased. The results indicate that laccase plays a larger role in atrazine biodegradation than Mn-peroxidase.