Effect of polyamines on superoxide dismutase activity under dexamethasone-induced apoptosis in rat thymocytes.

The intracellular redox state is of importance for cell growth, differentiation, and apoptosis through reactive oxygen species (ROS) functioning as metabolic fine-tuner. Optimal levels of polyamines are necessary for growth, differentiation, and apoptotic cell death while they also protect cell from ROS accumulation. We have carried out studies to find out the interrelation between these two distant metabolic pathways. For that purpose, the glucocorticoid-triggered programmed cell death of rat thymocytes has been used. Our data confirm that SOD activity (which testifies both to the level of ROS generation and antioxidative defense state) changes in response to programmed cell death conditions and to alteration of intracellular polyamines level. Thymocytes death induced by dexamethasone is partially mediated by polyamines content. Our data prove that one of the molecular mechanisms of thymocytes population resistance after dexamethasone treatment is an enhanced level of antioxidant defense. It is evident that in dexamethasone-treated rat thymocytes polyamines modulate signal transduction processes to apoptosis development via changes in cellular redox status.

Antimicrobial resistance of nosocomial strains of Staphylococcus aureus in Russia: results of a prospective study.

A total of 879 Staphylococcus aureus clinical isolates from 17 medical institutions in different regions of Russia were tested. Susceptibility to 18 antimicrobials was determined by agar dilution in accordance with the NCCLS recommendations. The most potent antimicrobials were glycopeptides, linezolid, and fusidic acid, to which no resistance was found. Other antimicrobials with low frequency of non-susceptibility were mupirocin (0.3%), trimethoprim/sulfamethoxazole (0.8%), quinupristin/dalfopristin (1.8%) and rifampicin (7.0%). Fluoroquinolones displayed moderate activity (5.8% of non-susceptible strains to moxifloxacin, 9.1% to levofloxacin, 13.1% to ciprofloxacin). High rates of non-susceptibility were found to clindamycin (27.1%), gentamicin (30.7%), tetracycline (37.1%), erythromycin (39.6%) and chloramphenicol (43.1%). The prevalence of oxacillin-resistant S. aureus (ORSA) was 33.5% and varied from 0% to 89.5% in different hospitals. ORSA were isolated most frequently in the burn units (77.5%), intensive care units (54.8%), trauma and orthopedics units (42.1%). This is the first multicenter study published of antimicrobial resistance of S. aureus in Russia which meets international standards.

[Complete amino acid sequence of catalase from the fungus Penicillium vitale]. / Polnaia aminokislotnaia posledovatel'nost' katalazy griba Penicillium vitale.

The polypeptide sequence of the unmodified catalase from Penicillium vitale containing 696 amino acid residues was deduced. The sequences of 76 tryptic peptides of the unmodified catalase, 63 tryptic peptides of the catalase with modified Lys residues, 48 peptides resulting from catalase cleavage by the Staphylococcus aureus V8 protease, and 9 fragments obtained by BrCN-treatment were considered, and a comparison with the sequences of other catalases was made.

[The kinetic and catalytic properties of Penicillium vitale catalase]. / Kineticheskie i kataliticheskie svoistva katalazy Penicillium vitale.

The steady-state kinetics of catalytic action of Penicillium vitale catalase has been studied. The enzyme reaction conforms to the Michaelis-Menten equation, which is shown by considering the initial velocity of the enzyme-catalytic reaction with increased concentrations of hydrogen-peroxide and sodium perborate. The parameter Km value is rather large (231-259) mM. On the other hand the Pen, vitale catalase is one of the more active enzymes and shows kcat values equal to 0.8-3.0 x 10(-6) s-1 and kcat/Km ratio of the order of 0.4-1.2 x 10(7) M-1 s-1. The enzyme reaction conforms to the Arrhenius equation when the temperature varied from 0 to 60 degrees C. It shows a slight temperature dependence and extremely low Ea value: 1.48 kcal/mol.

[Study of the subunit structure of catalase from Penicillium vitale]. / Issledovanie sub''edinichnoi struktury katalazy Penicillium vitale.

A molecule of Penicillium vitale catalase is shown to dissociate into subunits with the molecular weight 75-80 kDalton. When hemin is splitted off the molecule also disintegrates into subunits equalling 1/4 of the enzyme molecule. The amino acid composition and fingerprints of the catalase subunits were studied. It is supposed that N-terminal residue of the subunit is blocked.

[Immobilization of Penicillium vitale catalase on aminoethyl cellulose and properties of the obtained preparations]. / Immobilizatsiia katalazy Penicillium vitale na aminoetiltselliuloze i svoistva poluchennykh preparatov.

Preparations of Penicillium vitale catalase immobilized by aminoethyl cellulose (AE-cellulose) are obtained using two methods: by the enzyme covalent cross-linking with the carrier by glutaric aldehyde and by the covalent binding of catalase to the carrier aminogroups through the carbohydrate enzyme component. A dependence is established for the degree of catalase binding and catalase activity of the immobilized enzyme on the enzyme carrier in immobilization ratio. The optimal enzyme-carrier ratio in both cases is 10 mg of the enzyme per 1 g of the carrier. With such a ratio and binding by means of glutaric aldehyde 9.5 +/- 0.23 mg of protein is added to 1 g of the carrier with the 68.7 +/- 3.45% of the activity preserved, and in binding through the carbohydrate component of catalase 9.2 +/- 0.29 mg/g is added with preservation of 84.7 +/- 4.42% of the activity. Studies in properties of soluble and AE-cellulose immobilized catalase of P. vitale and determination of thermodynamic parameters of inactivation showed that the immobilized enzyme is more stable to the effect of temperature and extreme pH values than the soluble one.

[Stability of Penicillium vitale immobilized catalase in continuous decomposition of hydrogen peroxide]. / Issledovanie stabil'nosti immobilizovannoi katalazy Penicillium vitale pri dlitel'nom razlozhenii perekisi vodoroda.

The process of hydrogen peroxide continuous decomposition by the preparation of the fungus Penicillium vitale catalase immobilized by aminoorganosilica which were activated by glutaric aldehyde, cyanuric chloride or 2,4-toluylene diisocyanate. Catalase with an oxidized carbohydrate component was used as well. Such a modified enzyme was directly bound with the surface of aminocontaining silica and alumina. It is shown that in the process of H2O2 decomposition the preparations of immobilized catalase are inactivated. The decrease in its activity is described by a model which suggests that rates of hydrogen peroxide decomposition and enzyme inactivation are described by the first order equations. A method for calculation and prediction of mean time of continuous operation of columns with bound catalase and other immobilized enzymes is suggested in terms of the given model.

[Immobilization of Penicillium vitale Pidopl. et Bilai catalase by inorganic carriers]. / Immobilizatsiia katalazy Penicillium vitale Pidopl. et Balai na neorganicheskikh nositeliakh.

An efficient method is developed for P. vitale catalase immobilization through the oxidized carbohydrate enzyme component, using silochrome. The method provides the enzyme binding without losing its catalytic capacity in the immobilized preparation. When the enzyme is immobilized by high-dispersed silica containing isocyanate, aldehyde groups or active atoms of chlorine, 8, 15, and 20 mg of the enzyme is bounded per 1 g of the carrier, respectively, its catalytic capacity being completely retained. A dependence is established for the degree of catalase bonding and catalytic capacity of the immobilized enzyme of the enzyme carrier ratio in immobilization. The catalytic activity of the immobilized catalase preparations reaches 2 000 Becker units/l g. The preparations are stable in storage. Some of their properties are studied.