Structural and catalytic polymorphism of human enzymes: Novel potential platforms for biomedical diagnostics

This review focuses on some intermediate results on the path from the gene and enzyme structure to physiological responses and personalised medicine. Bioinformatics of genetic and protein-structural polymorphisms, theoretical methods of predicting the influence of single amino acid substitutions on the structure and catalytic activity of enzymes are considered. For a large group of enzymes, interrelations between genetic modifications, structural changes of the proteins and the detected physiological and clinical manifestations are discussed. In this respect, highly productive techniques to determine the catalytic activity of an enzyme as well as non-invasive proteomic approaches are of particular interest. A non-invasive proteomic analysis using mass-spectrometric protein identification of human exhaled breath condensate and tear fluids has been chosen.     

Adaptation of the body to the effects of stress increases the resistance of cardiac nuclei to damaging effects of single-chain exogenous DNA

The effect of adaptation to stress exposure on the resistance of nuclear DNA to damaging effect of one-chain exogenous DNA was investigated by flow cytometric fluorescence method. It was shown that after the administration of one-chain DNA in concentration of 50 micrograms/ml into the nuclei suspension almost half of nuclear DNA was damaged in control. In adaptation this phenomenon was 5.5 times less pronounced. When the one-chain DNA concentration was increased, this protective effect of adaptation remained. The possible mechanism of the DNA-protective effect of adaptation is under consideration.     

A kinetic model of the interaction of stable GTP analogs with a system of opioid receptors

The effect of a stable GTP analog, GppNp, on the agonist binding to rat brain opioid receptors was studied. It was shown that the nucleotide used at low concentrations activates, and at high concentrations inhibits the ligand interaction with the mu-, delta- and kappa-receptors. The inhibiting effect of GppNp on the formation of the morphine and D-Ala2, D-Leu5-enkephalin complexes with high affinity opioid receptor binding sites is due to the decrease of the ligand affinity for the corresponding sites. A kinetic model of the GppNp effect on high affinity binding sites stipulating that in the course of nucleotide binding the GTP-binding protein dissociates and that the N-protein alpha-subunits thereby formed are liberated into the surrounding solution, was proposed. It was demonstrated that GppNp can modulate the properties of opioid receptors in the absence of the ligand in a system and the inhibiting effect of GppNp depends on the concentration of membrane preparation.     

Desensitization as a reflection of receptor-enzyme system inactivation during a reaction. Kinetic model of the process

The kinetic regularities of the processes occurring in the system: receptor-adenylate cyclase complex under the effect of a hormone, an agonist or a neuromediator, were studied. Experiments with cell cultures revealed that the effector caused an impulse increase in cAMP and a decrease in the effector-stimulated activity of the adenylate cyclase complex. The above effects were considered within the framework of a kinetic model which takes into account the enzyme complex inactivation in the course of adenylate cyclase synthesis. The data obtained permit to explain the physiological effect of desensitization of the receptor-enzyme system with respect to the effector action as a result of inactivation of this system in the course of the reaction. Possible molecular mechanisms of inactivation are discussed.     

Protective effect of the aerosol immunization of mice with the polycomponent vaccine Immunovac VP-4 after the challenge of the animals with Klebsiella pneumoniae virulent strain

Used four schemes of the administration of the preparation with different time of the exposition of the animals in an aerosol chamber were tested with their subsequent intraperitoneal challenge with K. pneumoniae virulent strain K16. Irrespective of the number of immunization courses, the administration of the preparation made at intervals of 1 day, or daily, did not ensure any protective effect, but only led to an insignificant increase in their survival time in comparison with nonimmunized animals. After intervals between immunizations were increased to 3 days the protective effect of aerosol immumization was obtained (the survival rate was 65-80 % and considerably differed from that of the controls). The protective effect of aerosol immunization thus obtained was comparable with the effectiveness immunization made in a single subcutaneous injection. Aerosol immunization resulted in low antibody titers to the antigens contained in the vaccine, while after a single subcutaneous injection high antibody titers to Klebsiella and Proteus antigens were detected. The antigen-stimulated blast transformation of spleen lymphocytes in mice subjected to aerosol immunizations in 5 exposures was high. After subcutaneous immunization significant changes in such characteristics were detected on day 15. The data thus obtained were indicative of good prospects in the development Immunovac VP-4 as the medicinal form intended for use in aerosols.     

Auditory event-related potentials to the apparent auditory image motion

Auditory event-related potentials (ERP) were registered to the dichotically presented white noise stimuli (duration 1500 ms, band 150-1200 Hz). Abrupt or gradual change ofinteraural time difference in the middle of stimuli (750 ms after sound offset) was perceived as an apparent auditory image (AI) instant relocation or motion from the midline to one of the ears. In responses these stimuli two ERPs were observed: one to the sound onset, and second--to the onset of motion or AI relocation. ERPs to AI relocation differed from those to sound onset in longer components latencies (123 ms versus 105 ms for N 1,227 ms versus 190 ms for P2). In responses to AI motion component latencies were even longer (N1: 137 ms, P2: 240 ms); N1 amplitude was greater at sites contralateral to the AI motion direction.     

Responses of neurons in the primary auditory cortex of the cat to the auditory motion stimuli with variable interaural delay

Unit responses in the primary auditory cortex of anesthetized cats to stationary and apparently moving stimuli resulted from a static and dynamically varying interaural delay (ITD) were recorded. The static stimuli consisted of binaurally presented tones and clicks. The dynamic stimuli were produced by in-phase and out-of-phase binaurally presented click trains with time-varying ITD. Sensitivity to ITDs was mostly seen in responses of the neurons with low characteristic frequency (below 2.8 kHz). All cells sampled with static stimuli responded to simulated motion. A motion effect could take the form of a difference in response magnitude depending on the direction of stimulus motion and a shift in the ITD-function opposite the direction of motion. The magnitude of motion effects was influenced by the position of motion trajectory relative to the ITD-function. The greatest motion effect was produced by motion crossing the ITD-function slopes.