Antimicrobial Activities of Bacteriocins E 50–52 and B 602 Against Antibiotic-Resistant Strains Involved in Nosocomial Infections

The antimicrobial spectra of previously published bacteriocin E 50–52 (39 a.a.; 3,932 Da; pI = 8.5) and bacteriocin B 602 (29 a.a.; 3,864 Da; pI = 7.2) were determined. Named peptides were related to class IIa (pediocin-like) bacteriocins. Minimal inhibitory concentrations (MICs) of bacteriocins have been determined for bacterial isolates that were causative agents of nosocomial infections collected from Russian hospitals in 2003–2007, namely methicillin-resistant Staphylococcus aureus (MRSA) (n = 10); Acinetobacter baumannii (n = 11); Citrobacter freundii (n = 8); Escherichia coli (n = 9); Klebsiella pneumoniae (n = 10); Proteus spp. (n = 6); and Pseudomonas aeruginosa (n = 10). The majority of these tested isolates have been shown to be multidrug resistant and carry genetic determinants of antimicrobial resistance that were detected using polymerase chain reaction (PCR). The MICs of bacteriocin B 602 ranged from ≤0.025–1.56 μg/ml, and for bacteriocin E 50–52 from 0.05 to 6.25 μg/ml for all of 64 bacterial clinical isolates tested. Interestingly, the bacteriocins studied demonstrate activity on both Gram-positive and Gram-negative bacteria. Bacteriocins E 50–52 and B 602 show good activity against nosocomial bacterial agents resistant to many classes of modern antibacterials used in clinical practice. These bacteriocins should be examined as an alternative in treating infections caused by such agents.     

Simulations of the nonlinear stage of Farley-Buneman instability with allowance for electron thermal effects

The Farley-Buneman instability is a two-stream instability observed in the weakly ionized plasma of the E region of the Earth’s ionosphere. In the present paper, the effect of nonisothermal behavior of electrons on the development of this instability is investigated by numerical simulations. The instability is described using fluid equations for the electron density and temperature, a kinetic equation for ions, and Poisson’s equation. In contrast to most previous studies, the simulations are performed by numerically solving partial differential equations, rather than by the particle method. With allowance for thermal effects, the simulation results become more realistic, because the amplitudes of the perturbed electric field and plasma oscillations decrease and the instability develops over a longer time. It is shown that the influence of electron thermal effects is more pronounced at low values of the external electric field.     

The use of two-dimensional electrophoresis for the analysis of changes in the protein spectrum of the cardiac muscle during mouse ontogenesis

Using two-dimensional polyacrylamide gel electrophoresis, an analysis of protein spectrum of cardiac muscle of C57BL/6Y mice in the course of ontogenesis was carried out. It was found that some genes expressed in the embryonic muscle are repressed in the course of differentiation. Seven major polypeptides were revealed during cardiac muscle growth. The methodological aspects of the use of two-dimensional electrophoresis are discussed.     

A study of interaction of 7-aminoactinomycin D with DNA by fluorescence correlation spectroscopy

The investigation of interaction of 7-aminoactinomycin D with DNA is hampered at nanomolar concentrations by low quantum yield of the dye fluorescence and high adsorbability of the dye. It was found that, instead of the increase in the fluorescence of 7-aminoactinomycin D after binding with DNA, a decrease in the fluorescence takes place, because 7-aminoactinomycin D complexed with DNA exists in two states: photochemically active and inactive. The presence of the photochemically active state of 7-aminoactinomycin D causes an apparent increase in the diffusion coefficient upon embedding of 7-aminoactinomycin D into DNA. The data obtained allow one to state that 7-aminoactinomycin D: (1) forms dimers at micromolar concentration, (2) has two specific photodestruction times, and (3) binds with DNA more effectively than actinomycin D. Polarization measurements made it possible to estimate numerically the adsorption of 7-aminoactinomycin D on the walls of the measuring cell.     

Leptospirosis in the Southern Federal District of the Russian Federation

The retrospective and operative epidemiological analysis of leptospirosis morbidity on the administrative territories of the Southern Federal District during the period of 1990-2002 was carried out. The dynamics and tendencies of morbidity in individual administrative units of the region were shown. Materials on the negative influence of the emergency situation arising in the region as the result of the natural calamity in summer 2002 were presented. As shown in this work, timely decisions on the stabilization of epidemiological situation taken at the period of high flood and inundation in summer 2002 in the Southern Federal District and their efficient execution made it possible to keep the epidemiological situation in leptospirosis under control.     

Effect of neonatal influences on pain and audiogenic sensitivity and the content of monoamines in the adult rat brain

In adult Wistar, KM, and Wag/Rij rats, the threshold of pain sensitivity (tail-flick test) and degree of spasm attack in response to a strong sound were estimated after neonatal administration of Semaks (analog of ACTG4-10 fragment) or after placebo (administration of saline for the control of the effect of neonatal pain stimulation). These neonatal influences did no affect the rates of sensorimotor maturation at an early age (Fox tests), i.e., did not affect directly the physiological activity of rat pups at the age of up to 21 days. In all control rats injected with saline (pain stimulation), the latent periods of audiogenic attacks increased reliably, while their degree decreased. Administration of Semaks "raised" these parameters to the lvl of those in intact animals, i.e., increased the sensitivity to sound. Neonatal administration (per os) of caffeine to KM rats increased reliably the latent period of audiogenic attacks. The thresholds of pain sensitivity in the rats of all strains were significantly lower than in the intact control, just as the level of dopamine in the hippocampus of KM rats. These data are interpreted as an evidence of changes in the development of some brain systems in response to neonatal influences.     

Role of the electrostatic interactions in pre-orientation of subunits in the formation of protein-protein complexes

Theoretical estimation of contribution of the electrostatic interactions to pre-orientation of ribonuclease subunits in process of complex formation was carried out. The subunit was considered as a multipole consisting of partial charges of all atoms of the molecule. The object of investigation was a system of two subunits with their centers of gravity fixed at some distance in vacuum. It was proposed that each subunit independently could rotate freely around its fixed center of gravity. The relative orientation states of the subunits in such system were searched at which the system has electrostatic energy minima (equilibrium states). In first approximation the equilibrium states were found using especially designed approximate method for electrostatic interaction energy calculation, which permitted to calculate and compare the energies of the system in 24(5) (approximately 8 10(6)) states with different mutual orientation of subunits. The angular coordinates of the found equilibrium states were further specified by calculation with gradient sliding method. Angular coordinates of the equilibrium states and the shapes of energy surface cuts along each coordinate angle were calculated also for the intersubunits distances diminished down to 50 angstroms. The dispersions of the angular coordinates of equilibrium states caused by heat movement (at T=300 degrees) and their changes with shortening the distance between centers of gravity of subunits were estimated. Mutual orientation of subunits in the equilibrium states of the system under consideration was found to be similar to their mutual orientations in complex. Also it was found that relaxation time of the system, caused by electrostatic interaction of subunits, after removing the system from an equilibrium state, is much less in vacuum than the mean time between their Brownian collisions at room temperature. It follows from these results that in the case of ribonuclease in vacuum the electrostatic interactions of its subunits must be strong enough to realize the effective pre-orientation of subunits during their Brownian approach from distances of the order 100 angstroms. Preliminary consideration taking into account the effect of surrounding water molecules on the electrostatic interactions of ribonuclease subunits showed that weakening of the interaction must be much less than in the case when one uses in its calculation the macroscopic dielectric permeability value equal to 80. So the results obtained for vacuum seem to be true for water solution also. More strict theoretical analysis of this problem will be carried out in the following publication.     

Interannual changes in the biomass of the Black Sea gelatinous zooplankton

The 15 year changes in the total gelatinous biomass consistof a general trend to increase, from 250 gm^–2 in 1980to 2500 g m^–2 in 1995, and fluctuations with a periodof –4 years performed against the background of this trendin the upper 150 m layer. Different species occupying distincttrophic niches form these peaks. When represented as the percentageof the total zooplankton biomass, Aurelia aurita and Mnemiopsisleidyi exhibit the contra-phase fluctuations where a sharp increasein M.leidyi is accompanied by a decrease in the A.aurita biornass.     

Comparative analysis of the zeta-crystallin/quinone reductase gene in guinea pig and mouse

zeta-Crystallin is a novel nicotinamide adenine dinucleotide phosphate:quinone reductase, present at enzymatic levels in various tissues of different species, which is highly expressed in the lens of some hystricomorph rodents and camelids. We report here the complementary DNA (cDNA) cloning of zeta-crystallin from liver libraries in guinea pig (Cavia porcellus), where zeta-crystallin is highly expressed in the lens, and in the laboratory mouse (Mus musculus), where expression in the lens occurs only at enzymatic levels. A 5' untranslated sequence different from the one previously reported for the guinea pig lens cDNA was found in these clones. We also report the isolation of genomic clones including the complete guinea pig zeta-crystallin gene and the 5' region of this gene in mouse. These results show the presence of two promoters in the guinea pig zeta-crystallin gene, one responsible for expression at enzymatic levels and the other responsible for the high expression in the lens. The guinea pig lens promoter is not present in the mouse gene. This is the first example in which the recruitment of an enzyme as a lens crystallin can be explained by the acquisition of an alternative lens- specific promoter.      

Effect of substances that alter the level of intracellular cAMP on the reaction of human lymphocytes blast transformation]

Effects of cholera toxin, cholera anatoxin, theophylline and dibutyryl cyclic AMP (db-cAMP) on the PHA-induced DNA synthesis have been studied. It was shown that toxin, db-cAMP and theophylline suppressed mitogen-induced 3H-TdR incorporation and blast-transformation in a dose-related manner. When both toxin and theophylline were given together to PHA-stimulated lymphocytes, the inhibitory effects of these two agents were additive. The inhibitory effects of db-cAMP and theophylline were additive too. This inhibitory effects could be due to the elevation of intracellular cAMP. Cholera anatoxin exerted an inhibitory action on the PHA-stimulated lymphocytes. The inhibitory effects on lymphocyte DNA synthesis by anatoxin and theophylline were not additive. These results suggest that the effects of cholera toxin are mediated by cyclic AMP, but effects of cholera anatoxin may be associated with some other mechanism.