PubMed Health⌕ Search

Biomedical subjects

I B Pavlova

Publications and source records attributed to I B Pavlova.

At least 19 recordsLinked to original sources
PubMed1990

[The electron microscopic study of bacterial development in colonies. The heteromorphous growth of bacteria during the natural development of a population].

In this work data on the morphological features of the heteromorphous growth of bacteria in the process of the natural development of their population are presented. The authors believe that the heteromorphous growth of cells is inherent in the normal cycle of the development of bacteria in the population and that this process is reversible. It has certain regularities, common for different bacteria, in the variability of morphological manifestations and can be regarded as one of the stages of the natural L-transformation of bacteria.

Culture Media↗
PubMed1990

[Electron microscopic study of bacterial development in colonies. The morphology of bacterial colonies].

The morphology of colonies of some pathogenic Gram-negative and Gram-positive bacteria has been studied by scanning and transmitted electron microscopy. The presence of covers on the surface of cells in colonies has been revealed. The examination of colony fragments in ultrathin section has revealed that cells exist in associations and the elements of cell covers are differentiated in the form of fibrillar structures in the intracellular space. This investigation has shown that covers in the colonies of the bacteria under study should be regarded as their morphological feature playing an important role in the development of the infectious process.

Cell Membrane↗
PubMed1989

[The surfaces of colonies of Mycobacterium species studied in the scanning electron microscope].

The study of the morphology of the surface of several mycobacterial species differing in their pathogenicity by the methods of scanning and transmission electron microscopy has revealed that cells in such colonies and micrococlonies are associated and form one common layer of medium electron density. The cells in this layer are sharply outlined. The cover on the surface of mycobacterial colonies, revealed in this investigation, ensures the stability of mycobacteria in the environment and their resistance to the action of various chemical and physical factors.

Micropore Filters↗
PubMed1986

[Studies of the mechanism of bacterial inactivation after administration of the preparation Polchlor K].

The purpose of the study was to determine the effect of chloroiodic complex compound with non-ionic surface active substances such as Polchlor K on the kinetics of dying, activity of bacterial dehydrogenases and glucosidases as well as ultrastructure of bacterial cells on the example of Escherichia coli and Staphylococcus aureus. The evaluation of the kinetics of bacteria dying under the preparation activity revealed higher activity against E. coli than S. aureus. It was found that the preparation in bactericidal concentrations decreased significantly dehydrogenase activity in the examined microorganisms and also affects the changes in their ultrastructure. The cell dying was mainly due to structure-functional lesions in the cytoplasmic membrane--initially inactivation of respiratory enzymes localized inside the cytoplasmic membrane and furthermore its structural lesion.

Chlorides↗
PubMed1985

[Mechanisms of bacterial inactivation as affected by cation surface-active substances].

The death kinetics and ultratructure of gram-positive and gram-negative bacteria exposed to alkyldimethylammonium chloride were studied. It was shown that at low concentrations (0.0001 per cent) the agent had a pronounced bactericidal effect, which was higher with respect to the gram-positive bacteria. Impairment of the intactness of the cytoplasmic membrane, a vitally important organoid of the bacterial cell, was the main factor in the mechanism of action of the cationic surface-active substance. Membrane structures of various configuration and localization not associated with the cell division were detected in the cytoplasm of the dead bacteria. These structures are probably the result of self-assembly of the membrane lipid components broken under the action of the detergent.

Bacteria↗
PubMed1983

[Structural and functional analysis of the effect of cationic surfactants on Escherichia cells and spheroplasts].

The character of the growth of Escherichia culture after treatment with alkyl dimethylbenzyl ammonium chloride (a cation surface-active substance) has been studied. The action of the preparation at bacteriostatic concentrations is reversible and manifested only by the increased duration of the lag phase. The complete restoration of the processes ensuring the growth and mitosis of the cells usually occurs. The preparation causes disturbances in the permeability barrier of the cell membranes, appearing immediately on contact with cation surface-active substances. This compound affects the cytoplasmic membranes of Escherichia cells at extremely low concentrations (0.0001-0.0002%); as a result, the leakage of low-molecular substances from the cells occurs. These disturbances in permeability are not accompanied by the disappearance of nucleic acids from the cells. The preparation used at bactericidal and subbactericidal concentrations denatures high-molecular cell components to a variable degree. The study of the ultrastructure of cells and spheroblasts shows that alkyl dimethyl-benzyl ammonium chloride destroys the structure of the outer and cytoplasmic membranes, as well as the ribosomal apparatus of Escherichia cells.

Adenosine Triphosphatases↗
PubMed1983

[Mechanisms of the bactericidal action of hydrogen peroxide].

The comparative study of some aspects of the bactericidal action of H2O2 on Escherichia coli, Staphylococcus aureus and Bacterium subtilis wild-type cells and their mutants with lesions in the systems of the reparation of DNA has been carried out. Hydrogen peroxide has been shown to cause disturbances in the structure and permeability of the cell wall, the cytoplasmic membrane, as well as to induce ribosomal lesions and the ruptures of bacterial DNA. The activity of the systems responsible for the reparation of lesions in the cell genome plays an important role in the resistance of bacteria to H2O2.

Bacillus subtilis↗
PubMed1978

[Submicroscopic study of bacteria and spores under the effect of peracetic acid and various aspects of the mechanism of its action].

Microbial cells (E. coli and staphylococcus) and B. cereus spores were used in this work. Peracetic acid in a concentration of 0.005% caused the death of 99% of the microbes in 20 minutes, and 0.1% peracetic acid caused the death of 99% of the spores in 45 minutes. Changes in the surface and internal structures of the cells were revealed on the ultrathin sections of microbial cells and spores after the action of the preparation. The noted changes were explained by disturbance of permeability barrier and a high reactogenic capacity of the activated oxygen of peracetic acid.

Acetates↗