PubMed Health⌕ Search

Biomedical subjects

A I Kolpakov

Publications and source records attributed to A I Kolpakov.

At least 19 recordsLinked to original sources
PubMed2005

[Hexylresorcinol induces chromosome aberrations in mouse peripheral blood cells].

Hexylresorcinol has been demonstrated to induce chromosome aberrations in eukaryotic cells at doses of 0.5, 0.05, and 0.005 mg/g body weight. The metabolic transformation of hexylresorcinol in mice decreases its genotoxic effect. The mutagenic effect is retained for three days only after the administration of the highest dose of hexylresorcinol (0.5 mg/g); during the first two days, lower doses are also genotoxic. Therefore, hexylresorcinol doses lower than 0.5 mg/g body weight are metabolized within two days to the extent precluding the expression of the cytotoxic effect. After a single administration to mice, exogenous hexylresorcinol is transformed at a rate of 0.0025-0.025 mg/day.

Animals↗
PubMed2003

[Induction of SOS-response of cells exposed to autoregulatory factors of microorganisms].

Among examined microbial growth regulators of alkyl hydroxybenzene group (hexylresorcinol, methylresorcinol, and hydroxyethylphenol), only hexylresorcinol induces cellular SOS response, demonstrating a dose-dependent increase of the induction factor in the SOS chromotest with the Escherichia coli PQ37 strain. At the highest of used concentrations (100 micrograms/ml), hydroxyethylphenol and nonalkylated resorcinol were shown to exert a weak toxic effect, reducing the activity of constitutive alkaline phosphatase, but did not induce SOS response. Nontoxic methylresorcinol did not induce genome damage, which can trigger SOS functions. It is concluded that substitutions in phenolic ring affect genotoxic activity of alkylresorcinols.

Bacteria↗
PubMed1999

[The optimization of a method for determining RNAse activity by using high-polymer RNA].

Different methods for precipitation of free nucleotides are compared with the aim of improving the method for estimating RNAse activity. The precipitators were 0.75% uranyl acetate in 0.25% HClO4, 96% ethanol with MgCl2 in different concentrations, pure ethanol, and chlorine acid. Measurements of RNAse activity by means of 0.02M MgCl2 in 96% ethanol whose volume is equal to the reaction mixture were the optimal.

Bacillus↗
PubMed1998

[Use of exogenous ribonuclease for improvement of Lactobacillus biological properties].

The influence of exogenous RNAse on the dynamics of the acid formation by the industrial strain 8R-A3 of Lactobacillus plantarum, its antibiotic sensitivity and antagonistic activity was studied. In the presence of the RNAase growth stimulating dose both a decrease of the culture lag-phase and a more intensive accumulation of lactic acid in the incubation medium resulting in an increase of the Lactobacillus antagonistic activity were observed. It was shown that RNAase increased the Lactobacillus stability to tetracycline and erythromycin by 32 to 57 per cent as compared to the control.

Anti-Bacterial Agents↗
PubMed1996

[Change in various biological properties of Lactobacillus as affected by ribonuclease].

The influence of RNAse from Bacillus intermedius on the growth of the industrial strain Lactobacillus plantarum 8R-A3 was studied. It was shown that the stimulating effect of the enzyme depended on its dose and manifested itself in decreasing the growth lag phase. At the same time the growth stimulating dose of RNAse increased the Lactobacillus adhesion to the epithelial cells and promoted secretion of proteinases from Lactobacillus to the culture medium. The possible use of RNAse as a stimulant of the growth of industrial strains was demonstrated which is advantageous for colonization of the biological surfaces.

4-Aminobenzoic Acid↗
PubMed1994

[Effects of external biophysical factors on reproducibility of Escherichia coli characteristics].

The paper gives the results of examining the influence of external biophysical factors (inoculate's age, inoculative dose, cultivating temperature) on the reproducibility of changes in the formation of intercellular biophysical processes in the bacterial population. The conditions under which there is a high reproducibility (the error being 5-7%) of development dynamic parameters for E. coli are shown to be the age of an inoculate, 24 hours, the cultivating temperature, 24 degrees C, the inoculative dose is the dose corresponds to the baseline optical density of working liquor in the range of 0.025-0.050.

Bacteriological Techniques↗
PubMed1992

[The effect of Bacillus intermedius RNAse on the multiplication of Candida tropicalis yeasts].

The effect of Bacillus intermedius RNAse on the reproduction of Candida tropicalis and synthesis of the main biopolymers in the yeast cells. It has been found that stimulating action of the enzyme appears at the concentration of 10(-5)-10(-6) mg/ml and does not depend on the physiological state of the sowing culture. The connection between the increase of the ionic penetration and stimulation of the RNA and proteins synthesis in the yeast cells subjected to the RNAse action is shown. The mechanism of chromatine-associated RNA-polymerase activation is suggested to include the alteration of the ionic penetration of cells under the RNAse action.

Bacillus↗
PubMed1992

[The biochemical aspects of the stimulating action of exogenous RNAse].

A sequence of biochemical reactions in yeast from moment of RNAse interaction with cell membrane to cell division has been studied. RNAse addition in growth medium causes the increase of Ca2+ entering rate in cells in 2.4 times. Under this condition the increase of membrane enzyme adenylate cyclase correlating with the growth of cAMP content in cell and rise of cAMP-dependent protein kinase activity have been observed. A hypothetic scheme of cellular response on the RNAse effect is suggested.

Adenylyl Cyclases↗
PubMed1991

[The effect of DNAse I on bacterial growth depending on the cultivation conditions and on the physiological characteristics of the inoculate].

The stimulating effect of DNAase 1 on Escherichia coli reproduction has been studied depending on the content of slowly growing cells in the inoculation culture in the phase of delayed growth. Three cell fractions of E. coli have been obtained using the stepwise separation of the population in terms of buoyant density in the phase of delayed growth. In contrast to fractions I and II the fraction III contains cells with delayed growth, permeable to exogenous DNAase 1 and sensitive to the action of this enzyme. The faster growth of bacterial cells has been shown to be caused by the direct ferment action on the slowly growing cells. The autometabolites and autolysates don't take part in this process.

Bacillus subtilis↗
PubMed1987

[Effect of exogenous DNAses on various stages of DNA replication in microorganisms].

Effect of DNAase 1 on DNA synthesis and cell division was studied in microorganisms deficient in some stages of DNA replication initiation. The DNA synthesis induced by exogenous DNAase was found to be a replicative origin since it was registered from the "origin" of chromosomal replication under the conditions of initiation of proteins functioning. Stimulation of DNA synthesis in bacterial cells having mutations in DNA B and DNA G genes by DNAase 1 indicates that exogenous DNAases participate in replicative fork during the DNA synthesis.

DNA Replication↗
PubMedDate not supplied

[Changes in the trophic organization of mitotic cycle of Candida utilis after exposure to RNAse from Bacillus intermedius].

The effect of the RNase from Bacillus intermedius on the growth and trophic cycle of Candida utilis was studied. The RNase at concentrations of 0.001-0.01 microgram/ml stimulated yeast growth by 30-40% as compared to the control, reduced the mitotic cycle of the yeast by shortening its G1 phase, and decreased the number of exotrophic cells in the G1 phase to a minimum. It was suggested that RNase is involved in the regulation of the transition of cells from the exo- to endotrophic state.

Bacillus↗
PubMedDate not supplied

[The function of anabiosis autoinductors in microorganisms under blockade of metabolism].

Alkyl-substituted hydroxybenzenes (AHBs), which are auto-inducers of microbial dormancy (d1 factors), were found to stabilize the structure of protein macromolecules and modify the catalytic activity of enzymes. In vitro experiments showed that C6-AHB at concentrations from 10(-4) to 10(-2) M, at which it occurs in the medium as a true solution and a micellar colloid, respectively, nonspecifically inhibited the activity of chymotrypsin, RNase, invertase, and glucose oxidase. C6-AHB-induced conformational alterations in protein macromolecules were due to the formation of complexes, as evidenced by differences in the fluorescence spectra of individual RNase and C6-AHB and their mixtures and in the surface tension isotherms of C6-AHB and trypsin solutions. Data on the involvement of dormancy auto-inducers in the post-translational modification of enzymes and their inhibition will provide further insight into the mechanisms of development and maintenance of dormant microbial forms.

Adaptation, Biological↗
PubMedDate not supplied

[Stabilization of enzymes by anabiosis autoinducers as a possible mechanism of resistance of resting microbial forms].

Alkyl-substituted hydroxybenzenes (AHBs), auto-inducers of microbial dormancy (or d1 factors), were found to stabilize the structure of protein macromolecules, making them metabolically less active and more resistant to stresses. In vitro experiments with the Bacillus intermedius ribonuclease and chymotrypsin showed that the degree of the physical and chemical stability of these enzymes treated with AHBs depends on their concentration and incubation time. Experiments with RNase, which is capable of refolding, i.e., renaturation after heat denaturation, revealed that AHBs efficiently interact with both intact and denatured proteins. The data obtained allow the inference to be made that d1 factors may play the role of natural chemical chaperons, blocking metabolism in dormant cells through the formation of catalytically inactive thermostable complexes with enzymes.

Adaptation, Biological↗
PubMedDate not supplied

[Effect of Bacillus intermedius ribonuclease on properties of the yeast Saccharomyces cerevisiae].

Effects of Bacillus intermedius ribonuclease on physiological, biochemical, and consumer properties of baker's yeast Saccharomyces cerevisiae were studied. This enzyme improved the yeast raising strength and increased the cell tolerance to various adverse factors. The antistress effect of RNase correlated with an earlier start of the stationary growth phase and increased trehalose pool.

Bacillus↗
PubMedDate not supplied

[Dependence of the effect of RNAase from Bacillus intermedius on the growth of baker's yeast on the concentration of the exogenous enzyme].

Bacillus intermedius RNase added at a low concentration (0.001 microgram/ml) stimulated yeast growth, while a high RNase concentration (1500 micrograms/ml) was inhibitory to yeast growth. The inhibitory effect of RNase was transient and correlated with the increase in the trehalose pool of yeast cells. The number of unbudded cells in the yeast population tended to decrease under the action of low concentrations of bacillar RNase and to increase under the action of high concentrations of this enzyme.

Bacillus↗
PubMedDate not supplied

[Effect of membrane-active microbial autoregulators on the growth of cultured ras-transformed fibroblasts].

Differential effects on proliferation of individual vs. combined administration of high- and low-molecular-weight microbial autoregulators (extracellular RNase from Bacillus subtilis and anabiosis-inducing factor d1) are reported for the first time for cultured cells of higher eukaryotes. Proliferation of ras-transformed mouse fibroblasts was affected by both autoregulators dose-dependently. The cytotoxic activity of individual regulators was directly related to their concentration. Unlike RNase, factor d1 (which functions as a chemical chaperone) exerted reversible effects. Studies of the effects of combined administration of the autoregulators demonstrated that pretreatment of the cells with low-dose d1 decreased the toxicity of RNase. Higher doses of d1 were required to attenuate the effects of toxic agents with more pronounced membrane tropism. The results obtained suggest that a universal system regulating the physiological activity of cells is operative in taxonomically remote organisms. The operation of the system is based on sequential changes in the structural organization and function of subcellular structures, induced by low- and high-molecular-weight autoregulators.

3T3 Cells↗
PubMedDate not supplied

[Effect of thermal processing of Bacillus intermedius ribonuclease on its catalytic activity and biological properties].

Bacillus intermedius ribonuclease (binase), which is known to exert a growth-stimulating effect at low concentrations and a genotoxic effect at high concentrations, loses these abilities completely after exposure to 100 degrees C for 10 min, but retains approximately 96% of its catalytic activity and structural integrity. Other types of modification, such as photoinactivation and site-specific mutagenesis, gave rise to enzyme forms with unaltered structure but reduced (sometimes to trace amounts) catalytic activity. Genotoxicity was always proportional to the catalytic activity of the native enzyme, while a notable growth-stimulating effect may be exerted by enzymes with low activity. The loss of biological activity of thermoinactivated binase was related to the increase in the number of negatively charged groups on the enzyme surface, which led to a substantial decline in the adhesive properties of the enzyme.

Bacillus↗