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Biomedical subjects

V V Tets

Publications and source records attributed to V V Tets.

18 recordsLinked to original sources
PubMed2005

[Influence of cultivation conditions on bacterial DNA content and bacterial membrane permeability].

The study included measurement of intracellular and extracellular DNA content and evaluation of bacterial membrane condition during plankton growth and in isolated communities. This was performed at different stages of bacterial development and after heating at the temperature of heat shock system activation. The content of intracellular bacterial DNA in the community decreased after 72 hours of cultivation growth more prominently than during plankton growth. Change of intracellular bacterial DNA content in the community overtook the increase of membrane permeability, which may indicate the onset of apoptosis. Heating at 420' decreased the permeability of bacterial membranes in the community, but did not affect this parameter in the bacteria during plankton growth. Extracellular DNA was found in the matrix of the communities after 24 hours of growth. Appearance of this DNA after 48-74 hours of cultivation may be associated with apoptotic process.

Bacteria↗
PubMed2004

[Impact of exogenic proteolytic enzymes on bacteria].

The impact of papain, trypsin and the enzyme complex vobenzyme on formation of biofilms by grampositive and gramnegative bacteria was studied. The enzymes were shown to inhibit the biofilm formation. When applilied to the formed associations, the enzymes potentiated the effect of antibiotics on the bacteria located in them. An increase in the antimicrobial effect of various nonrelated antibiotics was not connected with a change in the bacteria susceptibility but likely resulted from higher bioavailability of the drugs in the presence of the enzymes.

Anti-Bacterial Agents↗
PubMed2003

[Pangenome].

A conception of general interaction between genetic information of different organisms is formulated. A new concept "Pangenom" is proposed for description of the total sum of genes of living organisms and viruses. Features of the Pangenom structure and processes controlling its saving and variability are discussed. It is demonstrated that this conception may be used in medicine for the aims of prognosis of epidemic situation, in particular, of newly spreading pathogen development of new methods of prophylaxis and diagnostics of oncological diseases, and also of the evaluation of possible consequences of molecular genetics and gene engineering interventions.

Animals↗
PubMed1991

[Contacts between the cells in bacterial colonies].

The interaction of cells in microbial colonies has been studied by electron-microscopic techniques. Two types of contacts between cells have been found to exist in the colonies of Gram-negative bacteria of the genera Escherichia, Shigella and Salmonella: close cell adhesion due to the fusion of cell-wall outer membranes and the formation of intersections consisting of membranous tubules. At the sites of close adhesion the fusion of cytoplasmic and outer membranes have been found to occur in Bayer's zones. In the colonies of Gram-positive bacteria of the genera Staphylococcus and Brevibacterium only one type of contacts has been revealed: the fusion of the peptidoglycan layers of the cell walls. The results of this study indicate that in colonies bacteria are not completely isolated; their interaction leads to the formation of a three-dimensional structure denoted as a cooperative cell system.

Bacteria↗
PubMed1991

[Changes in virulence of Enterobacteriaceae in the presence of sub-inhibitory levels of antibiotics].

The effect of subinhibitory concentrations of antimicrobial agents such as chloramphenicol, tetracycline, rifampicin and nalidixic acid on various factors of virulence in Shigella spp. and enteroinvasive colon bacilli was studied. It was shown that under such conditions changes took place in various events of the interaction with the epithelial cells, i.e. in adhesion, penetration, intracellular multiplication and transfers between contacting cells. The total effect of chloramphenicol resulted in increasing of the virulence while that of nalidixic acid, tetracycline and rifampicin resulted in its decreasing.

Anti-Bacterial Agents↗
PubMed1990

[Activation of the alarm response of Escherichia by antibiotics].

The data on the effect of antibiotics suppressing the synthesis of protein on the activation of the SOS-system are presented. The action of tetracycline, chloramphenicol rifampicin and nalidixic acid, a well-known activator of SOS-response, has been studied. The short-term action of inhibitory concentrations and the prolonged action of subinhibitory concentrations of these preparations on the activity of genes rec A and sul A and the induction of the synthesis of phage lambda have been considered. Chloramphenicol and tetracycline, as well as nalidixic acid, have been shown to be capable of activating genes rec A, sul A and synthesis of the phage. The induction of SOS-response has been found to be more pronounced in the short-term action of inhibitory concentrations of antibiotics on bacteria than in the prolonged subinhibitory concentrations.

Alkaline Phosphatase↗
PubMed1987

[Effect of SOS repair in enterobacteria on their interaction with the complement system].

The interaction of E. coli (serovar 0124) and its rec A-mutants with serum complement resulting in the alternative pathway activation was studied. Bacteria VT1240 (original smooth strain), VT1241 (rough mutant) and VT 2240 (recA56 mutant) were shown to be complement-sensitive when treated with 1.5 X 10(8)--1.9 X 10(8) cells per ml of normal human serum, while the cells with SOS-activated system (recA441 mutant, strain VT3251) retained their viability. An alternative pathway of complement activation was minimal with E. coli VT1241, while VT3251 demonstrated intermediate activity. To decrease the level of complement components (AH50) and factor B (BH50) by 50%, 3.5 X 10(6)--4.5 X 10(6) cells of VT1240 and VT2240 strains were required. R-mutants and recA441 mutants caused a 50% reduction in AH50, when used in the amount of 6.4 X 10(7) and 2.6 X 10(7), respectively, the same degree of BH50 decrease was achieved with the amounts used equal to 1.1 X 10(8) and 4.3 X 10(6), respectively. C3 conversions caused by 4 X 10(8) cells in I ml of the normal human serum in the four strains tested accounted for 5-15%.

Complement Pathway, Alternative↗
PubMed1987

[Significance of rec A-gene activity in altering the ultrastructure of Escherichia coli].

The pathogenic E. coli strain, serovar 0124 studied in this investigation and its mutants rec A 56 and rec A 441 differ in their ultrastructural organization. In strains having defects in gene rec A, the appearance of intracytoplasmic membranous structures and a great number of extracellular membranous vesicles, as well as the formation of the filamentous forms of cells in the colonies, can be observed. These data indicate that the product of gene rec A plays an active role in the metabolism of bacterial membranes.

Escherichia coli↗
PubMed1985

[Determination of the structural integrity of DNA from pathogenic enterobacteria].

Among the enterobacterial strains under study, more organisms in the stationary phase of growth have been found to have nicks in their DNA than those in the exponential phase. Bacteria less sensitive to ultraviolet irradiation have the least number of nicks in each phase of growth. The number of nicks in different strains belonging to the serovar is sufficiently stable. Virulent and avirulent forms show no difference in this characteristic.

Animals↗
PubMedDate not supplied

[Quantitative characterization of antagonistic activity of lactobacilli].

In this work the method of serial dilutions of lactobacilli in two-layer agar was used. On the agar surface bacterial or fungal cultures were applied at different time intervals. A special quantitative characteristic was introduced. L. plantarum strain 8P-A3 was shown to have the maximum antagonistic activity. In great amounts L. casei and L. reuteri are capable to suppress the growth of bacteria and fungi. All lactobacilli under study produced a pronounced bactericidal effect on Pseudomonas, had different influence on the viability of Escherichia and staphylococci and exhibited fungistatic and fungicidal action only when inoculated at high concentrations.

Antibiosis↗
PubMedDate not supplied

[The effectiveness of antibiotics on bacteria in biofilms].

Bacteria can form different types of communities, united by common notion: biofilms. The aim of the present study was to determine the capacity of different antibiotics to penetrate into biofilms and act on unrelated bacteria. The study revealed that the formation of barriers between the community and the environment on artificial biofilms occurred in all strains of unrelated Gram-positive and Gram-negative bacteria used in this investigation. The capacity of antibiotics to penetrate into biofilms varied in different strains of the same species. For certain antibiotics similarity in their penetrating capacity was found to exist with respect to biofilms of unrelated bacteria. The penetration of antibiotics into mixed biofilms depended on the strain which determined its minimal value, so that the protection of one microorganism by another was thus observed. The method for the evaluation of the effectiveness of antibiotic penetration into bacterial biofilms, suitable for use in bacteriological laboratories, is proposed.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Purine and pyrimidine bases entering the composition of DNA and RNA studied by gas-liquid chromatography].

A methods for gas chromatographic analysis of purine and pyrimidine bases, occurring DNA and RNA, is described. Preparation of samples for analysis is discussed. Procedures are described, which enable to perform rapid and quantitative analysis of the nitrogenous bases. Minimal volumes of the materials to be studied might be analyzed with high reproducibility.

Chromatography, Gas↗
PubMedDate not supplied

[The design and study of an ogt deletion mutant of Salmonella typhi].

The chromosome of S. typhi, similarly to those of Escherichia coli and Salmonella typhimurium, was found to contain ogt gene. Using Cmr gene, flanked by the corresponding sites of Salmonella chromosome, we managed to create S. typhi ogt deletion mutant strain. As shown in this study, ogt gene, together with giving protection against alkylating, methylating, ethylating and propylating agents, played an important role in protection against other mutagenic factors. In contrast to the wild strain, S. typhi ogt deletion mutant strain was found to be sensitive to UV radiation, pesticides and antimicrobial preparations.

Anti-Bacterial Agents↗