Analysis of ligand-receptor binding by the difference method

A new method has been proposed for analysis of experimental data on ligand-receptor binding at equilibrium. This method makes it possible to detect heterogeneity of a receptor system in cases where the contribution of the high-affinity site to total binding is rather small and the problem of graphic discrimination of a model cannot be solved unambiguously by other methods. The difference method permits us to exclude experiments on measuring nonspecific binding. A computer program for analysis of ligand-receptor binding has been worked out in which the difference method and traditional methods of binding isotherm analysis are realized. Numerical modeling has shown that the best strategy in experimental data processing is the treatment of total binding isotherms by both the difference method and regression analysis, including the nonspecific binding constant as one of the regression parameters.     

Receptor-enzyme interactions. Kinetic characteristics

The kinetic regularities characterizing the behaviour of enzyme-receptor systems underlying molecular mechanisms of transmission and transformation of current information at the cellular level are reviewed. The properties of receptors as molecular detectors responsible for chemical signal "recognition" are described, and the efficiency of enzyme-substrate and effector-receptor interactions is compared. The heterogeneity of receptor populations and kinetic approaches to their discrimination are considered. The principal mechanisms and problems of chemical signal amplification in coupled enzymatic reactions are discussed. The major properties of the ligand-receptor system and its relation to gene expression in receptors as well as mechanisms of cell response "quenching" are reviewed. Some kinetic regularities of desensitization of enzyme-receptor systems are discussed in terms of present-day concepts on desensitization as inactivation of enzyme-receptor systems in the reaction course.     

Mismatch negativity in the auditory event-related potentials in response to abrupt and smooth displacements of virtual sound source

The work investigated event-related potentials, mismatch negativity (MMN), and P3a component under dichotic stimulation with deviant stimuli simulating abrupt or smooth displacement of auditory images to the left or to the right from the head midline by means of interaural time delay introduced into the deviant stimuli. Repetitive standard stimuli were localized near the head midline. All deviant stimuli elicited mismatch negativity and P3a component. It was shown the MMN for smooth deviant motion was lower than that for the abrupt deviant displacement. MMN amplitude for both deviant types obviously depended on interaural time delay, which confirms that MMN might be considered as a measure of the auditory system spatial discriminative ability. The P3a component demonstrated the same amplitude dependences as the MMN. The results obtained are discussed in respect to manifestation of the processes underlying the auditory motion detection in the event-related potentials.     

Exogenous proteins in exhaled human breath condensate

In the course of analysis of protein composition of exhaled breath to diagnose diseases of the respiratory system the problem is raised to distinguish between proteins, expressed in lung tissues and in respiratory tract (endogenous) and those that got into the respiratory system from the ambient air in the process of respiration (exogenous). In this work, an attempt is made to estimate the constitution of exogenous proteins in exhaled air with mass spectrometry and nanoflow high performance liquid chromatography (nano-HPLC). Six months’ indoors isolation of healthy donors with air being cleaned of dust leads to the removal from the spectrum of exhaled proteins of some keratins that are therefore considered to be exogenous. Nonkeratin proteins may also circulate between ambient air and human airways, but their concentration appears to be significantly lower than keratin concentrations (especially than the epidermis keratin). Among nonkeratins, dermicidin seems to be the most significant exogenous protein of the exhaled air. Conclusions concerning the diagnostic value of exhaled proteins can be made only after careful comparison of results of quantitative and qualitative analyses of their normal and pathological composition for a statistically significant sample of donors.     

Delineation of the cell-extrinsic apoptosis pathway in the zebrafish

The mammalian extrinsic apoptosis pathway is triggered by Fas ligand (FasL) and Apo2 ligand/tumor necrosis factor (TNF)-related apoptosis-inducing ligand (Apo2L/TRAIL). Ligand binding to cognate receptors activates initiator caspases directly in a death-inducing signaling complex. In Drosophila, TNF ligand binding activates initiator caspases indirectly, through JNK. We characterized the extrinsic pathway in zebrafish to determine how it operates in a nonmammalian vertebrate. We identified homologs of FasL and Apo2L/TRAIL, their receptors, and other components of the cell death machinery. Studies with three Apo2L/TRAIL homologs demonstrated that they bind the receptors zHDR (previously linked to hematopoiesis) and ovarian TNFR (zOTR). Ectopic expression of these ligands during embryogenesis induced apoptosis in erythroblasts and notochord cells. Inhibition of zHDR, zOTR, the adaptor zFADD, or caspase-8-like proteases blocked ligand-induced apoptosis, as did antiapoptotic Bcl-2 family members. Thus, the extrinsic apoptosis pathway in zebrafish closely resembles its mammalian counterpart and cooperates with the intrinsic pathway to trigger tissue-specific apoptosis during embryogenesis in response to ectopic Apo2L/TRAIL expression.     

Perception of short musical fragments by hypomaniac patients

Emotional assessment of short fragments from pieces of chamber music was studied in patients in steady elated mood (hypomaniac). Six fragments, assessed by healthy subjects as emotionally positive, neutral or negative were used. The examined subjects were shown to be capable for an emotional assessment of the musical fragments. The most pronounced difference of the examined patients from healthy subjects and depressive patients examined earlier was the predominance of neutral assessments in hypomaniacs.     

Kinetic Instability of Zero Steady State As a Fundamental Cause of Low Efficiency of Chemotherapy of Cancer

Using mathematical modeling of the process of cancer treatment by the classical chemotherapy methods and therapy with biological agents, the effect of the kinetic parameters of the model on the final outcome of treatment was studied. It is established that the complete cure (i.e., the formation of a stable steady state with a zero number of cancer cells) cannot be reached by means of only classical chemotherapy.     

Microalgae as source of biofuel,food, fodder,and medicines

Current status and future prospects of such problem as the production of microalgae and their application for biofuel generation (biodiesel, biohydrogen, bioethanol), as well as other products, is discussed in the review. The use of microalgae in human food, fodder, cosmetics, dyes, polysaccharides, antioxidants, medicines, and other products is quite promising. Presently, microalgae are noncompetitive with plant materials, due to economic reasons, in serving as a source of biofuel. Thereby, it is urgently necessary in modern biotechnology to improve the methods for the production of microalgae and search for new ways of their processing.