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A V Naumov

Publications and source records attributed to A V Naumov.

At least 19 recordsLinked to original sources
PubMed2006

Experimental evidence of the local character of vibrations constituting the Boson peak in amorphous solids.

We report the first measurement of the density of states of low-energy vibrational excitations in a disordered solid via single-molecule (SM) spectroscopy. Optical spectra of many single tetra-tert-butylterrylene (TBT) molecules embedded to amorphous polyisobutylene (PIB) as spectral probes were recorded at low temperatures. The T dependences of SM spectral linewidths showed the broad distribution of local frequencies of vibrations under study. The obtained distribution was compared with the "Boson peak" in pure PIB measured in [R. Inoue, J. Chem. Phys. 95, 5332 (1991)] by neutron scattering. We found that embedding of a small amount of TBT into PIB does not influence markedly on the observed vibrational dynamics. These results prove the local character of low-energy vibrational excitations in glasses and the existence of relationship between these excitations and the Boson peak.

Journal Article↗
PubMed2003

Lévy statistics for random single-molecule line shapes in a glass.

We demonstrate that the statistical behavior of random line shapes of single tetra-tert-butylterrylene chromophores embedded in an amorphous polyisobutylene matrix at T=2 K is described by Lévy statistics as predicted theoretically by Barkai, Silbey, and Zumofen [Phys. Rev. Lett. 84, 5339 (2000)]. This behavior is a manifestation of the long-range interaction between two-level systems in the glass and the single molecule. A universal amplitude ratio is investigated, which shows that the standard tunneling model assumptions are compatible with the experimental data.

Journal Article↗
PubMed2003

[Xenon effects on cells and receptors].

Xenon (Xe) is being more widely used in medicine owing to its unique physical-and-chemical properties of a noble gas. However, the knowledge about the physiological and patho-physiological changes occurring in the organism and in its separate structures during the interaction with Xe is still scanty. The aim of this survey was to briefly describe the presently known Xe biological-and-medical properties and certain mechanisms of Xe impact produced on cells and receptors as well as on the release of mediators and hormones. Besides, the Xe hemodynamic effects are also defined. The conclusion is that the Xe effect can be of a complex nature and can depend on the conditions of the body vital activity (optimal condition, activation, lesion), which predetermine, in their turn, the performance of the structural-and-functional units of various cellular systems.

Adrenal Glands↗
PubMed2002

Models of 2,4,6-trinitrotoluene (TNT) initial conversion by yeasts.

The original models of the initial steps of 2,4,6-trinitrotoluene (TNT) conversion by yeasts are presented. Saccharomyces sp. ZS-A1 reduced nitro groups of TNT producing isomeric monohydroxylaminodinitrotoluenes (HADNT) as the key initial metabolites (molar ratio HADNT/TNT was up to 0.81), whereas aminodinitrotoluenes (ADNT) and the hydride-Meisenheimer complex of TNT (H-TNT) were the minor products. Conversely, Candida sp. AN-L13 transformed TNT almost quantitatively into H-TNT, thus realizing the alternative attack, consisting of the TNT aromatic ring reduction. The third type of conversion, revealed in Candida sp. AN-L14, is the combination of both above mechanisms and produces an equimolar mix of HADNT and H-TNT. In the toxicity tests with Paramecium caudatum, the supernatant of Saccharomyces sp. ZS-A1, which converts TNT into HADNT, was most toxic while the supernatant of Candida sp. AN-L13 (TNT --> H-TNT) was least toxic. The microorganisms converting TNT quantitatively to the reactive metabolites can be useful for their immobilization through the detoxifying interaction with the soil components such as humic compounds.

Aerobiosis↗
PubMed2001

Purification and characterization of a salicylate hydroxylase involved in 1-hydroxy-2-naphthoic acid hydroxylation from the naphthalene and phenanthrene-degrading bacterial strain Pseudomonas putida BS202-P1.

1-Hydroxy-2-naphthoate is formed as an intermediate in the bacterial degradation of phenanthrene. A monooxygenase which catalyzed the oxidation of 1-hydroxy-2-naphthoate to 1,2-dihydroxynaphthalene was purified from the phenanthrene- and naphthalene-degrading Pseudomonas putida strain BS202-P1. The purified protein had a molecular weight of 45 kDa and required NAD(P)H and FAD as cofactors. The purified enzyme also catalysed the oxidation of salicylate and various substituted salicylates. The comparison of the Km and Vmax values for 1-hydroxy-2-naphthoate and salicylate demonstrated a higher catalytic efficiency of the enzyme for salicylate as a substrate. A significant substrate-inhibition was detected with higher concentrations of 1-hydroxy-2-naphthoate. The aminoterminal amino acid sequence of the purified enzyme showed significant homologies to salicylate 1-monooxygenases from other Gram negative bacteria. It was therefore concluded that during the degradation of phenanthrene the conversion of 1-hydroxy-2-naphthoate to 1,2-dihydroxynaphthalene is catalysed by a salicylate 1-monooxygenase. Together with previous studies, this suggested that the enzymes of the naphthalene pathway are sufficient to catalyse also the mineralization of phenanthrene.

Amino Acid Sequence↗
PubMed1993

[Effect of plague microbe fraction 1 protein-polysaccharide complex and pure protein on metabolic parameters of macrophages].

The investigation reveals different influence of the plague microbe's fraction 1 polysaccharide-protein complex and of it's purified protein on the 5'-nucleotidase activity and on the chemiluminescence response of peritoneal macrophages. Both of these metabolic indexes were found to be dependent on the dose of fraction 1 and duration of time till examination.

5'-Nucleotidase↗
PubMed1992

[A comparative cytofluorimetric analysis of the blood leukocytes in guinea pigs exposed to the phospholipase D and antigens of the causative agent of plague].

The influence of Y. pestis phospholipase D on the physiological state of leukocytes in the blood of guinea pigs was studied in vivo by flow impulse fluorometry with the use of fluorochrome acridine orange. During the first hours of observation the intensity of leukocyte fluorescence increased due to a rise in the number of polymorphonuclear leukocytes and changes in the permeability of cell membranes. Further changes in the intensity of the fluorescence of the material under study after 24 hours of observation occurred due to the appearance of activated lymphocytes in the blood stream. The processes normalized by day 21. The reaction of blood leukocytes to phospholipase D was specific in comparison with the reaction to capsular antigen, "mouse" toxin, lipopolysaccharide and the main somatic antigen.

Animals↗
PubMed1992

[Plasmid determined degradation of sulfo-aromatic compounds by Pseudomonas sp. BS1304].

Utilized sulfo-aromatic compounds of Pseudomonas sp. BS1304 were isolated. It was shown that the first step of conversion is desulfonation with following meta-cleavage of the substituted aromatic ring. At least two steps are controlled by the plasmid pBS1004 (120 kb), belonging to the IncP-9 incompatibility group. The degradative plasmid marked by Tn5-lac may be mobilized to P. putida, P. aeruginosa, P. mendocina, where a degradative phenotype is expressed.

Arylsulfonates↗
PubMed1991

[An oral chemical vaccine from the hypertoxigenic strains of the causative agent of cholera KM-76 Inaba and KM-68 Ogawa].

The material on the development of chemical vaccine, prepared from two newly formed strains (KM-76 Inaba and KM-68 Ogawa) and intended for oral administration, is presented. The conditions for the submerged cultivation of these strains have been established, which makes it possible to increase the production of choleragen 8- to 10-fold and O-antigen 3- to 4-fold in comparison with V. cholerae natural strain 569B. The maximum accumulation of neuraminidase, protease, phospholipase, along with choleragen, has been registered in the logarithmic phase and that of O-antigen, in the stationary phase of growth. The use of strains KM-76 and KM-68 has led to the fourfold increase of the specific activity of the main immunogens, thus permitting the respective increase of the yield of the oral vaccine without changes in its high capacity for the formation of specific antibodies and its low residual toxigenicity.

Administration, Oral↗
PubMed1990

Association-dissociation processes and supermolecular organisation of the capsule antigen (protein F1) of Yersinia pestis.

The association-dissociation processes involving the capsule antigen of Yersinia pestis were investigated. In aqueous salt solutions the material of the capsule (protein F1) exists in the form of associated species containing identical monomeric protein subunits. Brief heating (100 degrees C, 3 min) of F1 dissolved in buffered salt solutions at pHs between 4.4 and 7.5 leads to dissociation of the antigen into oligomers which reassociate at room temperature into aggregates of high molecular mass. In the presence of 7 M urea and 0.1% SDS such reassociation is suppressed. It is shown that a few seconds after heat treatment the protein exists as the tetramer in phosphate buffer and as the dimer and the monomer in the presence of urea and SDS respectively. Interconversions of these three forms of the antigen were observed on replacement of one buffer by another. The effect of pH, ionic strength, F1 concentration, and temperature on the rate of association of F1 were also investigated. A decrease in pH, an increase in the ionic strength of the solution, and an increase in the concentration of the protein in aqueous buffered salt solutions all accelerate the F1 aggregation process. A model is proposed for the supermolecular structure of the F1 protein associated species in which the subunits are assembled into a single plane containing tens of dimers as a result of lateral interdimer hydrogen bonds. The dimer is stabilised by hydrophobic interactions of the nonpolar sections of the subunits, which in the associated protein form an internal hydrophobic surface analogous to that in lipid bilayer membranes.

Antigens, Bacterial↗
PubMed1990

[Lipid peroxidation in the adrenal cortex during exhausting stress].

Under prolonged stress which is connected with exhaustion of functional resources of adrenal cortex the activation of lipid peroxidation processes in this gland was found. It is possible that the reason for such lipid peroxidation activation is the decrease in the content of adrenal cortex ascorbic acid and alpha-tocopherol.

11-Hydroxycorticosteroids↗
PubMed1989

[Methodology of determining Yersinia pestis antigens using dot-immunologic analysis].

The technique of dot-immunoassay on nitrocellulose filters is described for the detection of the vital infection (VI) agents. The results are read visually (qualitatively) and instrumentally (quantitatively). The method is highly sensitive (3.2 +/- 0.8 ng/ml of fraction I) and specific, cost-effective, simple, and available for laboratories engaged in VI diagnosis.

Antigens, Bacterial↗
PubMed1987

[Transport of basic amino acids into Yersinia pestis cells].

The transport of the basic amino-acids into the plague microbe cells has been shown to proceed by means of two transfer systems, the common transfer system and the system specific for lysine. Besides that, arginine can be transported into the plague microbe cells by the histidine transport system. The vaccine strain EV NIIEG was used as a model to study the amino-acid transport systems.

Amino Acids↗