Response of the spinal trigeminal nucleus neurons to electric stimulation of the rat dura mater

Aseptic inflammation of tissues surrounding large meningeal blood vessels, e.g. the superior sagittal sinus, underlies pathogenesis of migraine. This inflammation develops due to antidromic activation of sensory trigeminal nerve endings and is followed by changes in responses of the spinal nucleus of the trigeminal nerve neurons to electrical stimulation of the superior sagittal sinus. However, characteristics of these reactions are still unclear. In experiments ou urethane-anesthetized rats, responses of 387 neurons of the spinal nucleus of the trigeminal nerve to electrical stimulation of the superior sagittal sinus, were recorded. It was tial discharge with the latency 7 to 19 ms (11.4 +/- 0.17 ms) and a subsequent long-lasting discharge with the latency 20 to 50 ms (34.2 +/- 0.8 ms). It is presumed that the first phase reflects orthodromic activation of prevascular A delta and C-fibers of the trigeminal nerve while the second phase is connected with activation of meningeal C-fibers which have low conduction velocity, and/or with a secondary activation of perivascular sensory endings of trigeminal nerve by releasing algogenic and vasoactive substances. These changes could be used as an indicator of efficacy of some antimigraine substances in animal experiments.     

Genetic variability of the nucleocapsid protein of the virus of the porcine reproductive and respiratory syndrome

The porcine reproductive and respiratory syndrome (PRRS) is a contagious viral pathology caused by PRRS virus. There are 2 types of the above virus--the European and American ones. Distribution patterns of the PRRS virus were studied for Russia and Byelorussia. Above 700 porcine sera obtained from 32 households of 21 Russia's administrative regions and from 19 households of 6 Byelorussia's administrative regions were tested for presence of antibodies to the PRRS virus. Simultaneously, the samples were tested for virus presence by polymerase chain reaction (PCR). It was proven serologically that the PRRS virus is widespread in the territories of Russia and Byelorussia. Noteworthily, all field isolates found in Russia and Byelorussia belong to the European type. Not a single viral isolate of the American PRRS type was found. The nucleocapsid (N) recombinant protein was obtained on the basis of the Russian field isolate of the PRRS virus by using the E. coli. expression system. Finally, it was shown as possible to use the recombinant protein in indirect immune enzyme assay for the sake of detecting the antibodies to the PRRS virus.     

Model of three dimensional structure of the immunodominant epitope of gp120 HIV(Thailand)

The geometry of five preferred structures of the immunodominant epitope of the HIV(Thailand) protein gp120, derived earlier from the NMR spectroscopy data, was refined using the quantum chemical methods. As a result, (i) the energy characteristics of the initial structures were improved significantly, (ii) their relative locations on the scale of formation heats were determined, and (iii) the energy barriers dividing the conformers under study were computed. On this basis, only two out of five starting structures were proposed as biologically relevant conformations for the virus immunogenic crown. The results obtained are discussed in connection with the literature data on the structure of the HIV-1 principal neutralizing determinant.     

Semax and Selank Inhibit the Enkephalin-Degrading Enzymes of Human Serum

Dose-dependent effect of synthetic heptapeptides Semax (Met-Glu-His-Phe-Pro-Gly-Pro) and Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) on the enkephalin-degrading enzymes of human serum was demonstrated. The inhibitory effects of Semax (IC₅₀10 M) and Selank (IC₅₀20 M) are more pronounced than that of puromycin (IC₅₀10 mM), bacitracin, and some other inhibitors of peptidases. Beside the heptapeptides, their pentapeptide fragments also possessed an inhibitory effect; tri-, tetra- and hexapeptide fragments did not display such an effect. As the above enzymes take part in degradation of not only enkephalins but also other regulatory peptides, it can be assumed that one of the mechanisms of biological activity of Semax and Selank is related to this inhibitory activity of theirs.     

Orienting reflex: "targeting reaction" and "searchlight of attention"

The concept of orienting reflex based on the principle of vector coding of cognitive and executive processes is proposed. The orienting reflex to non-signal and signal stimuli is a set of orienting reactions: motor, autonomic, neuronal, and subjective emphasizing new and significant stimuli. Two basic mechanisms can be identified within the orienting reflex: a "targeting reaction" and a "searchlight of attention". In the visual system the first one consists in a foveation of a target stimulus. The foveation is performed with participation of premotor neurons excited by saccadic command neurons of the superior colliculi. The "searchlight of attention" is based on the resonance of gamma-oscillations in the reticular thalamus selectively enhancing responses of cortical neurons (involuntary attention). The novelty signal is generated in novelty neurons of the hippocampus, which are selectively tuned to a repeatedly presented standard stimulus. The selective tuning is caused by the depression of plastic synapses representing a "neuronal model" of the standard stimulus. A mismatch of the novel stimulus with the established neuronal model gives rise to a "novelty signal" enhancing the novel input. The novelty signal inhibits current conditioned reflexes (external inhibition) contributing to redirecting the behavior. By triggering the expression of early genes the novelty signal initiates the formation of the long-term memory connected with neoneurogenesis.     

Slow Relaxation Process in DNA

A dynamic transition at temperatures 200–230K is observed in manyhydrated bio-polymers. It shows up as a sharp increase of the mean-squaredatomic displacements above this temperature range. We present neutronscattering data of DNA at different levels of hydration. The analysis showsthat the dynamic transition in DNA is related to a slow relaxation processin the MHz-GHz frequency range. This slow relaxation process iscompletely suppressed in the dry DNA sample where no dynamic transitionwas observed. The nature of the slow process is discussed. We ascribe it toa global relaxation of DNA molecule that involves cooperative motion ofmany base-pairs and backbone.     

Stability of microbial association in the process of industrial biofiltration cleaning of gaseous discharges

Results of industrial exploitation of a biofiltration plant tailored for purifying gaseous discharges of hazardous organic components such as toluene, cyclohexane, and xylene, are examined. Both numerical and compositional variations were monitored for a long-term (more than 1.5 years) utilization process in an association of microorganisms decomposing organic pollutants. A population of microbial association composed by one yeast and two bacterial strains in the biofilm on the surface of filtering sheets was abundant (10(8)-10(9) yeast cells/cm2 and 10(10)-10(11) bacterial cells/cm2) and stable during the whole period of monitoring. A microbial association in the culture medium averaging 10(6) yeast cells/l and 10(8) bacterial cells/l is more susceptible to technogenic impacts and seasonal fluctuations. Overall, the biofilter as an open and autonomic system maintained its microbial association, thereby providing a high-degree (93-98%) purification of industrial gaseous discharges from organic pollutants.