Перегляд за Автор "Taradina, G.V."

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    Deterministic approximation of stochastic spatially explicit model of actin-myosin interaction in discrete filament lattice
    (2018) Mishchenko, A.M.; Dotsenko, O.I.; Taradina, G.V.
    One of commonly used approaches of biophysical modeling of muscle contractile apparatus is spatially explicit discrete lattice models in Monte Carlo simulation. Such models allow to reproduce structural features and actin-myosin interaction in the muscle contractile system more accurately. Limitation of such models is their low computational efficiency and stochasticity under certain circumstances. This work introduces deterministic approximation of stochastic model that considers a pair of rigid contractile filaments interaction. Approximation background is discreetness of spacing between cross-bridges and binding sites. Due to this property cross-bridges can be divided into discrete groups with the same strain, and considered statistically using the set of ordinary differential equations. Deterministic model is more computationally efficient, operates with average values. Within the given approach isotonic contraction was simulated. A comparison with Monte Carlo simulation demonstrates that approximation reproduces results for stochastic model with large number of cross-bridges. Also within the deterministic model a mechanism and essential conditions for oscillations appearance in isotonic transient response, relations of their parameters with geometrical ones of filaments lattice were examined, theoretical and experimental results were compared. The proposed approach can also be applied to approximation of continuous Huxley-based models solutions. Advantage over existing numerical methods is their greater numerical stability.
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    Документ
    Enzyme protection systems of erythrocytes in conditions of ascorbate recirculation and oxidative loading
    (2018) Dotsenko, O.I.; Taradina, G.V.; Voronych, M.V.
    Vitamin C was shown to partially protect red blood cells from oxidative changes during storage by noticeable reduction of mechanical fragility and hemolysis. In order to maintain the content of ascorbate in the reconstituted form in plasma, the latter is involved in a number of oxidative-reducing processes within red blood cells. This work is a continuation of studies of the effects of ascorbate on the metabolic processes that maintain the viability of red blood cells. Human red blood cells were incubated for five hours at 25 ºC in the oxidizing media system 1 – 1.0 · 10–4 M ascorbic acid (AscH), 5 · 10–6 M Cu2+, Na-phosphate buffer (0.015 M, pH 7.4), 0.15 M NaCl, and system 2, that contained o-phenanthroline at a concentration of 1.0 · 10–4 M in addition to the components of system 1 medium. For these cells, the changes in the content of reduced glutathione, glutathione enzyme activity, and the state of the membrane electron transport NADH: ferricyanide reductase were determined in time. The obtained data indicate that red blood cells undergo significant oxidative stress under the influence of the oxidative medium. During the first incubation period of erythrocytes in the AscH-Cu2+ environment, the activity of glutathione peroxidase and glutathione-S-transferase reached the maximum values, indicating the presence of H2O2 in the cell and the activation of lipid peroxidation processes. Glutathione-S-transferase activity remained above the control level throughout the entire study period. The activity of glutathione reductase and glucose-6-phosphate dehydrogenase was reduced. The oxidative loading of erythrocytes in the presence of o-phenanthroline was lower, the development of oxidative stress occurred in 90 minutes, but the binding of the o-phenanthroline complexes of Cu2+ to the membrane modified the SH-group of membrane proteins and this reduced the transport capabilities of the dehydroascorbate transporters and the electron transmembrane system, the consequence of which may be the accumulation of oxidized forms of ascorbate outside. We detected the participation of CO-signaling mechanism in hemoglobin deglutathionylation and increase in the content of glutathione. In this work we discuss the role of metabolic reprogramming in red blood cells through thiol-disulfide exchange as a mechanism that can be involved into adaptive responses aimed at counteracting stress in mammalian tissues.