Том 64, № 4 (2019)

Abstract—The capabilities of computer analysis of the conformational properties of proteins and the nature of their interactions with ligands are rapidly growing due to the development of molecular modeling methods and advances in computer technology. Despite this, the existing theoretical methods are still far from ideal and their predictions require experimental verification. Therefore, accurate experimental methods for measuring the parameters of interaction between proteins and small molecules are in high demand to address both fundamental and applied issues, such as the study of intracellular processes and the creation of new drugs. In this review, we consider three well-proven modern biophysical techniques for the determination of the affinity, stoichiometry, and energy of the interaction of proteins with ligands: isothermal titration calorimetry, microscale thermophoresis, and surface plasmon resonance. Particular attention is paid to the development of the technical capabilities of these methods in recent years, the intricacies of their practical use, and illustrations of their application to solve specific biophysical problems in pharmacology.

Abstract—The affinity of binding of pandemic influenza A/California/7/2009 (H1N1pdm09) virus for fetuin and mucin was studied. Three methods based on the enzyme-linked immunosorbent assay for the quantitative determination of receptor specificity of influenza virus strains were compared. These methods were competitive Dixon plot analysis in direct coordinates, a competitive method using the half-maximal inhibitory concentration (IC₅₀), and a kinetic method. It has been found that competitive methods significantly distort the result due to unspecific binding of competitive proteins, while the kinetic method prevents such an effect. In the future, it can be widely used to accurately measure the receptor specificity of the influenza virus with α2-3 and α2-6 type receptors.

Abstract—Confocal microscopy and colocalization analysis using Pearson correlation coefficients were used to show that esterified chlorin e₆ derivatives and their liposomal forms are mainly localized in the endoplasmic reticulum, Golgi complexes, cell mitochondria, and levels of their localization in lysosomes are low. Cellular uptake and accumulation kinetics of chlorin e₆ derivatives were strongly depended on the type of pharmacological formulation used for photosesitizers administration, while intracellular localization was independent on the formulation. Differences in the photodynamic activity and sensitization mechanisms for chlorin e₆ derivatives and their liposomal forms were shown when compared to those of chlorin e₆ photosensitizers in K562 cells. It is assumed that the observed differences in the mechanisms of cellular damage are to a greater extent due to specific photosensitizer localization.

Abstract—The phenolic compound purpurogallin (PPG) is found in oak nutgalls and is a red pigment with a benzotropolone ring structure. PPG shows pronounced cytoprotective and anti-inflammatory activities. PPG might be effective in preventing and treating diverse systemic inflammatory diseases, affecting functional activities of various cell metabolic and signaling pathways that are associated with inflammation. A study was made to compare the antioxidant (free radical) properties for PPG, dihydroquercetin (DHQ), ascorbic acid, and trolox using two test systems, hemoglobin (Hb)–H₂O₂–luminol (LM) and 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH)–LM. PPG was additionally tested for its effect on the permeability of flat lipid bilayer membranes (LBMs). Moderate antioxidant activity was observed for PPG in the Hb–H₂O₂–LM system; its neutralizing potential towards hydroxyl and superoxide anions was comparable with that of ascorbic acid. The compounds were ranked according to the efficiency of their antioxidant activity in the system: DHQ > trolox > ascorbic acid > PPG. Interestingly, when the AAPH–LM system was used to test antioxidant activity, PPG did not show neutralizing activity towards peroxyl radicals formed in the system. PPG did not significantly change the permeability of flat LBMs in a dose range of 1.5–30 μM, suggesting lack of a primary membrane effect. Putative mechanisms and characteristics of cytoprotective, antioxidant, and anti-inflammatory activities of PPG are discussed.

Abstract—The production of reactive oxygen species in human erythrocytes during incubation in the presence of a glycerol–mannitol mixture and polyethylene glycol with a molecular weight of 1500 Da, as well as during hypothermic storage of cells cryopreserved under their protection, was studied. Analysis of the production of reactive oxygen species was carried out by flow cytometry using fluorescence indices of dichlorofluorescein. It was found that incubation in the glycerol–mannitol mixture, as well as cryopreservation and subsequent hypothermic storage, did not cause activation of the production of reactive oxygen species in erythrocytes. Polyethylene glycol caused the intensification of the production of reactive oxygen species both during incubation and storage of cryopreserved erythrocytes under hypothermia. Peculiarities of changes in the intensity of the production of reactive oxygen species in erythrocytes under the influence of cryoprotective agents and cryopreservation may have a significant impact on the stability of cells under stress and their ability to maintain functional integrity after returning to physiological conditions.

Abstract—It is shown that the lower intensity of 2,7-dichlorodihydrofluorescein oxidation processes in inactivated neutrophils exposed to hypomagnetic field (the residual static magnetic field 20 nT) is not related to calcium-mediated mechanisms as shown by the absence of the effect of cell-permeant Ca²⁺ chelators, such as 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester), on the intensity of the process. This decrease is hardly likely to be caused by effects of a hypomagnetic field on phosphorylation of NADPH-oxidase components, because addition of the protein kinase C inhibitor Ro 31-6233 decreases the fluorescence intensity of intracellular dichlorodihydrofluorescein little, if at all. Addition of phospholipase C inhibitor U73122 causes a negligible decrease in ROS production in the control and experiment, almost equally. Different concentrations of apocynin increase ROS production in nonactivated neutrophils and this effect is approximately two times lower under hypomagnetic conditions. The decrease in ROS production is more pronounced in cells treated with a hypomagnetic field with the presence of rotenone, indicating that the mitochondrial electron-transport chain is involved in the mechanism of the effect of hypomagnetism.

Abstract—The results of satellite monitoring of vegetation on unused agricultural lands during the growing season of 2018 are presented. Sod fields of different ages (2, 7, and 20 years) and bare fallows on the land used by the Krasnoyarsk Research Institute of Agriculture were the objects of the study. Satellite data with high spatial resolution (Sentinel-2 Earth remote sensing satellites) at the pre-processing Level-1C (https://earthexplorer.usgs.gov/) were used for the interpretation of sod field and fallow images. These data were used to calculate the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Soil Index (NDSI). Algorithms and software for the processing of Sentinel-2 satellite data were developed. The possibility of using NDVI dynamics for assessment and monitoring of the condition of sod fields and bare fallows has been demonstrated. The applicability of the NDSI soil index for assessment of the status of arable land has been demonstrated.

Abstract—The seasonal dynamics of atmospheric pressure and geomagnetic activity in the regions with different climates were analyzed to calculate the seasonal variations in the partial density of oxygen. Based on the data we obtained, an attempt was made to explain possible causes and mechanisms of synchronization of circannual rhythms under standard laboratory conditions. Analyzing our data and that of other researchers, we concluded that the atmospheric pressure and the partial density of oxygen can be considered as additional synchronizers of the organismal circannual rhythms since these parameters are characterized by the explicit seasonal dynamics. It was also shown that mechanisms exist that are responsible for the involvement of these meteorological factors in the process of synchronization of biological rhythms.

Abstract—This paper presents the results of a study of the oxygen supply to olfactory cells, which is required for olfactory signal transduction of chemical and mechanical stimuli triggered by olfactory receptors located in the membrane of sensory cilia that extend into the mucus layer that covers the olfactory epithelium. Experiments were conducted on olfactory epithelia isolated from male Wistar rats without symptoms of rhinitis. The oxygen uptake rate (pO₂) in the mucus covering the olfactory epithelium was measured using a micropolarographic method prior to a response to odor molecules, that is, a mixture of n-butanol and amyl alcohol, and during its stimulation. The results show that the oxygen uptake rate was almost four times higher in the mucus covering the olfactory epithelium than in the odor solution, suggesting an intense diffusion of oxygen through the olfactory mucus. It was also found that under the action of odorants, pO₂ in the mucus decreased from 43.1 ± 1.8 to 35.9 ± 1.8 mmHg (n = 53). Oxygen supply to olfactory flagella from the olfactory mucus in response to chemical and mechanical stimuli may be a prerequisite for high sensitivity and rapid kinetics of olfactory transduction processes.

Abstract—The mechanism of the resonance effect of microwave radiation on the brain of laboratory animals was revealed. It was established that microwave radiation releases tryptophan molecules, initiating a multistage process of phase transformations of albumin molecules, namely, a three-stage conformational transition of the albumin globule to the coiled state. Free tryptophan that penetrates into the brain with the cerebrospinal fluid flow through the Virchow–Robin space, increases the production of serotonin in the neural network of the brain by affecting serotonergic receptors.

Abstract—This paper reports an analysis of a stochastic model of ion dynamics in the cardiac pacemaker cell within the framework of the generalized two-oscillator Maltsev–Lakatta model, including the electron-conformational model of ryanodine receptors. It has been demonstrated that generation of an action potential depends significantly on the nature of the interaction between the external membrane and the internal (Ca²⁺ clock) oscillators. Constructive interaction between oscillators leads to the formation of a stable action potential, while destructive interaction leads to parasitic effects, in particular, to arrhythmias. The effects of the model parameters that are characteristic of the rabbit sinoatrial heart node on the shape of the time dependence of the cell membrane potential has been investigated. The conditions under which spontaneous transition to the abnormally fast oscillatory mode takes place have been determined and the mechanism of this transition has been described; the pacemaker cell behavior in tachycardia has actually been simulated. It has been demonstrated that suppression of the rapid potassium current leads to the recovery of the normal oscillation mode of ion dynamics in a pacemaker cell, which corresponds to the mode of action of class III antiarrhythmic agents.

Abstract—A thermophysical model of heat transfer from a liquid heated by radiation into biological tissues with a cyst of an individual picture of temperature fields, which takes the parameters of laser radiation, as well as the individual thermodynamic and morphometric characteristics of the object of exposure and its syntopy, into account, is proposed. The model is designed for algorithmization of performance of laser-induced indirect thermotherapy of cavity tumors. A comparison was made between the theoretical prediction of the dynamics of temperature changes in the wall of a Baker’s cyst and the experimental data obtained using a thin needle thermocouple placed through a needle in the center of a cyst filled with liquid, whose dimensions had been previously determined by magnetic resonance imaging. It was shown that at the heat transfer coefficient of 3000 W/(m² K) the proposed model described the heating of the cyst contents due to heat transfer from its inner wall accurately.

Abstract—From the standpoint of a new theory of chaos and self-organization with the use of novel modeling methods, the dynamics of the behavioral cues of a student’s psychological state in multifaceted activity have been analyzed. The Bourdon attention test modified by P.A. Rudick was used to measure attention levels. A comparative statistical analysis of the results has been carried out to assess the properties of attention in students of different ages who live in the Surgut and Samara regions. The dynamics of the changes in the K, E, and A variables have been explored and the coefficients have been calculated for the entire test and for each minute of the experiment. The characteristics of the attention development in students have been investigated and the age- and sex-related differences, as well as the difference in the attention indices in students, have been determined.