Biofizika最新文献

The possibility of producing the material based on collagen and biologically active polyphenol taxifolin was explored, and the properties of the material were studied. The data on the dynamics of the release of polyphenol chemically linked to collagen are represented, and the metal-reducing activity of polyphenol released from the gel is determined. The effect of taxifolin, taxifolin glutarate and gel containing polyphenol on the production of reactive oxygen species by neutrophils stimulated with phorbol myristate acetate was examined. It was shown that polyphenol released from the gel material exerts antioxidant and metal-reducing properties, suggesting that unoxidized polyphenol linked to collagen.

Activity of the key enzyme of the cytochrome part of the respiratory chain--cytochrome oxidase, quantitative redistribution of mitochondrial cytochromes b, c1, c and aa3, activity of the key enzymes of cytochromes' heme metabolism--delta-aminolevulinate synthase and heme oxygenase under conditions of acetaminophen-induced hepatitis against the background of alimentary deprivation of protein were studied. It was found out, that under conditions of acetaminophen-induced hepatitis against the background of alimentary deprivation of protein, an inhibition of cytochrome oxidase activity and a decrease in the quantitative content of mitochondrial cytochromes against the background of the increase in the delta-aminolevulinate synthase and heme oxygenase activity are observed. In animals with toxic liver injury, maintained under conditions of alimentary deprivation of protein, a progressive decrease in the quantitative content of mitochondrial cytochromes b, c1, c and aa3 against the background. of the increase in heme oxygenase activity and preservation of delta-aminolevulinate synthase activity on the control level is identified. The conclusion was made, that alimentary deprivation of protein is a critical factor for the development of the disturbances of structural-functional integrity of the cytochromic part of the respiratory chain. The identified changes may be considered as one of the possible mechanisms of energy biotransformation system disturbances under conditions of alimentary deprivation of protein.

A mathematical model of tumor growth is developed taking into account angiogenesis. Malignant cells under metabolic stress produce vascular endothelium growth factor that stimulates angiogenesis, increasing nutrient influx in tumor. The model takes into account the migration and proliferation dichotomy in the malignant cells depending on nutrient concentration. Convective fluxes originated due to active tumor cell proliferation in compact dense tissue are also considered. The computational analysis of the model has demonstrated that diffusive tumor growth rate does not depend on angiogenesis while for non-invasive tumors angiogenesis can significantly alter tumor growth, although it is not able to stop it completely. The causes and significance of the result for estimation of the antitumor efficacy of antiangiogenic therapy are discussed.

With the method of molecular dynamics, pairs of amino acid residues have been identified on the surface of the interacting formin mDial domains: DID-DAD, which are responsible for the autoinhibition of formin, and the GTPase Rho-DID domain, and control activation. It was found that the most stable interactions are ionic interactions between Glu178 residue and Arg248 residue, as well as hydrophobic interactions between Thr175 and Phe247. The strongest interactions proved to be between the DID domain with Rho-GTPase. These interactions are mediated by specific triple ionic interactions between positively charged amino acid in Rho, and a triplet of amino acids in DID, consisting of two negatively charged amino acids, separated by one uncharged. Binding sites for Rho-GTPase and DAD partially overlap, but various amino acids on the DID participate in interactions with different domains. We discuss the possible conformational changes in formin domains during activation and inactivation.

The method of event-related brain potential (ERP) investigation was suggested. This method aims at obtaining an estimate of a structure of the chains of the local, maxima, obtained from wavelet-transform ERP matrix. The common approach for ERP analysis was represented. With this approach it was possible to form and detect the chains of the local maxima and minima of wavelet-transformation ERP matrix, The algorithms for adaptive recovery of ERP elements after forward wavelet-transform were described based on time scaling signals depicting separate elements of event-related components. When using the method for estimation of visual ERP it was found out that ERP components were formed with no less than 2-3 elements. These elements were the time and frequency domains. These domains being the basis for the adaptive recovery of ERP elements, having their certain latent time and amplitude features, can be independently of clinical and physiological importance. This method showed its stability toward the change in wavelet function (Morlet, WAVE) used during analysis. This method was used for SSVEP analysis. The new elements in SSVEP were detected. These elements were not constantly present in SSVEP spectrum.

The concept of active medium is used as a biophysical basis for modeling spatial and temporal self-organization in anthropogenic ecosystems that results in formation of regular dynamic structures with stable or unstable modes of development. Urban ecosystem is represented as a hierarchy of interacting active media, and their non-linearity is the result of extreme anthropogenic load and mismatch between characteristic times and scales in evolution of the natural and anthropogenic components together with the complex set of positive and negative feedbacks between the subsystems. Description of the presented model is deliberately simplified so as to use a modified Fitz-Hugh-Nagumo equation. The approach developed here is quite general and allows for systematic description of urban ecosystems as distributed dissipative systems.

A three-wave epidemic cycle caused by a new serotype agent is simulated. The mechanism of stepwise recession in a stratum of the susceptible persons is examined. A group of asymptomatic infected individuals as well as an antigen activity index, which regulates the intensity of input streams into the groups of infected patients, are introduced into the model. Morbidity rate is additionally regulated by the virulence. The model is identified according to the observations of the three-wave passage of Hong-Kong serotype (H3N2). On the basis of the simulation results it is shown that a leading role in upgrading the virulence capacity of the agent and in replenishment of the morbid group is assigned to the asymptomatic infected individuals.

The formation of cholesteric liquid-crystalline dispersions formed by double-stranded DNA molecules, handled by positively charged superparamagnetic cobalt ferrite nanoparticles, as well as action of these nanoparticles on DNA dispersion, are considered. The binding of magnetic nanoparticles to the linear double-stranded DNA in solution of high ionic strength (0.3 M NaCl) and subsequent phase exclusion of these complexes from polyethylene glycol-containing solutions lead to their inability to form dispersions, whose particles do possess the spatially twisted arrangement of neighboring double-stranded DNA molecules. The action of magnetic nanoparticles on DNA dispersion (one magnetic nanoparticle per one double-stranded DNA molecule) results in such "perturbation" of DNA structure at sites of magnetic nanoparticles binding that the regular spatial structure of DNA dispersion particles "blows up"; this process is accompanied by disappearance of both abnormal optical activity and characteristic Bragg maximum on the small-angle X-ray scattering curve. Allowing with the fact that the physicochemical properties of the DNA liquid-crystalline dispersion particles reflect features of spatial organization of these molecules in chromosomes of primitive organisms, it is possible, that the found effect can have the relevant biological consequences.

Employing bacterial model systems it was shown that the introduction of the soluble compound--sodium salt of cobalt octacarboxyphthalocyanine (teraphtal)--into the medium led in an ultrasonic field to a decrease in the proportion of survived bacteria. It is suggested that in the bacterial environment teraphtal forms a solid phase, which in the ultrasonic field causes destruction of the structures adjacent to the nanocrystals due to localized cavitation processes.

The method for analysis of chlorophyll fluorescence transient using approximation of measured signal by multi-exponential series is described. Visualization of partial sums of this series allows us to find amplitudes and characteristic times of individual phases of fluorescence induction curve. This method gives more rigid criteria of phase identification instead of semi-empirical approach currently used. Applied to Chlamidomonas reinhardtii sulfur deprivation case, it shows efficiency in finding visually undistinguishable phases of fluorescence transient for early detection of stress.