[Contraction (retraction) of blood clots in patients with ischemic stroke]. / Kontraktsiya (retraktsiya) sgustkov krovi u bol'nykh s ostrym ishemicheskim insul'tom.

AIM: To study a possible pathogenetic role of the blood clot contraction and its disturbances in the acute stage of ischemic stroke (IS). MATERIAL AND METHODS: Using a new instrumental technique to study the dynamics of clot contraction in vitro, the authors have determined quantitative parameters of clot contraction (the extent and rate of contraction, duration of the lag-period) in the blood of 85 patients with acute IS. RESULTS AND CONCLUSION: The contractile activity of blood clots was substantially reduced compared to the blood of healthy subjects. Correlations between hemostatic and contractile parameters suggest that the reduced clot contraction in stroke is due to the lower platelet count and impaired platelet functionality, higher levels of fibrinogen and antithrombin III as well as higher hematocrit and hemoglobin contents, leukocytosis, and changes in the biochemical blood composition. The results show that the reduced ability of clots may be a novel pathogenic mechanism that aggravates the course and outcomes of IS.

[Effect of Bacillus pumilus ribonuclease on the paramagnetic centers of microbial cells].

Potential clinical application of Bacillus pumulus cytotoxic ribonuclease (binase) selectively inducing the death of tumor cells makes it imperative to investigate its effect on the normal human microflora. Flow cytometry was used to determine that binase concentration causing the apoptosis of cancer cells had no effect of the viability of Escherichia coli K12. The changes in the paramagnetic centers of E. coli K12 cells in the presence of nontoxic binase concentrations revealed by EPR spectroscopy included higher EPR signals from iron-containing proteins (including those from the Fe-S clusters) and of the Mn(II) hyperfine structure. The TMTH spin probe (N-(1-hydroxy-2,2,6,6-tetramethylpiperidine-4-il)-2-methylpropanamide hydrochloride) was used to reveal a twofold increase in the levels of reactive oxygen species (ROS) in the cells, which induced oxidative stress in the enzyme-treated bacteria. Inductively coupled plasma mass spectrometry revealed elevated contents of alkaline (Li, Na, K), alkali earth (Mg, Ca), transition (Cr, Mn, Fe, Cu, Zn), and post-transition metals (Bi, Pb) in the cells. Elevated levels of Cu and Zn (which impair the activity of the respiratory chain enzymes) and of Mn, which is known as a superoxide dismutase cofactor, confirmed development of the oxidative stress in bacteria.

[Manganese in atherogenesis: detection, origin, and role].

The role of transition metal ions in atherogenesis is controversial; they can participate in the hydroxyl radical generation and catalyze the reactive oxygen species neutralization reaction as cofactors of antioxidant enzymes. Using EPR spectroscopy, we revealed that 70% of the samples of aorta with atherosclerotic lesions possessed superoxide dismutase activity, 100% of the samples initiated Fenton reaction and demonstrated the presence of manganese paramagnetic centers. The sodA gene encoding manganese-dependent bacterial superoxide dismutase was not found in the samples of atherosclerotic plaques by PCR using degenerate primers. The data obtained indicates the perspectives of manganese analysis as a marker element in the express diagnostics of atherosclerosis.

Participation of oxygen in the bacterial transformation of 2,4,6-trinitrotoluene.

The exposure of Bacillus cereus ZS18 cell suspensions to 2,4,6-trinitrotoluene (TNT) in the absence of other oxidizable substrates increases oxygen uptake, exceeding the basal level of respiration of the bacterium 1.5- and 2-fold with 50 and 100 mg/liter of TNT, respectively. The interaction of both living and to less extent dead bacterial cells with TNT results in the accumulation of superoxide anion (O2*-) in the extracellular medium, which was revealed by the EPR spectroscopy. The accumulation of O2*- decreased by 50-70% in the presence of Cu,Zn-superoxide dismutase of animal origin. In the presence of living bacterial cells, the level of TNT decreased progressively, yielding hydroxylaminodinitrotoluenes together with O2*-. In the presence of heat-killed cells, a moderate decrease in TNT was observed, and the appearance of O2*- was not accompanied by the production of any detectable TNT metabolites. Chelating agents inhibited the transformation of TNT and decreased the formation of O2*-. The demonstrated generation of O2*- during the interaction of TNT with K4[Fe(CN)6] together with the observed effects of chelating agents suggest the participation of iron in the one-electron reduction of TNT and the functioning of an extracellular redox cycle with the involvement of molecular oxygen.