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Biomedical subjects

L V Didenko

Publications and source records attributed to L V Didenko.

At least 19 recordsLinked to original sources
PubMed2005

Ultrastructural study of chitosan effects on Klebsiella and staphylococci.

Antibacterial effect of chitosan on the morphofunctional organization of clinical strains of Klebsiella pneumoniae and Staphylococcus aureus was studied by transmission electron microscopy. Chitosan promoted aggregation of bacterial cells and disorganization of bacterial cell wall and cytoplasmic membrane, which leads to the release of bacterial contents into the environment. These structural changes result in bacterial death.

Bacterial Capsules↗
PubMed2001

[Ultrastructural analysis as a method of studying bacteremia in infectious diseases].

To study bacteremic processes with transmission electron microscopy, blood groups were examined in the representative groups of patients with typhoid fever, generalized forms of yersinosis, pseudotuberculosis, Flexner's shigelosis, and Sonne's shigelosis at different stages of acute cyclic diseases and in those with chronic Salmonella typhi carriage. Bacteremia of typical unaltered causative organisms is shown to occur only in the feverish period of disease. The morphofunctional organization of a causative agent in this period is similar to that of museum bacterial strains, except that the bacteria circulating in the blood of patients have vesicles that are morphologically equivalent to endotoxin. In reconvalescence, the blood circulation of causative organisms continues, but they appear as morphologically changed bacteria and as forms with their defective cellular wall (spheroplasts and protoplasts). Transmission electron microscopy reveals bacteria of other systematic groups in the patients' blood when acute Salmonella typhi carriage is under way or when there are typhoid fever-induced complications or relapses, clinically unfavorable running of typhoid fever, generalized forms of yersinosis and pseudotuberculosis are present. In chronic Salmonella typhi carriage, the patients' blood displays altered bacterial cells and forms with defective cell wall, among them there are prominent morphological types that are structurally identical to uncultured bacterial forms. The study of blood samples from infected patients has show that transmission lectron microscopy can be used to detect blood circulating microorganisms at different stages of acute and chronic patterns of an infectious process.

Bacteria↗
PubMed2000

[Ultrastructural organization of Salmonella typhimurium cells during long-term starvation and transfer to an unculturable state].

Electron microscopic and immunocytochemical studies of Salmonella typhimurium culture were carried out under conditions of cell transfer into an unculturable state induced by carbon, phosphorus, and nitrogen starvation. Morphological variants of bacterial cells were detected in the course of cell culturing under conditions of starvation. Electron microscopy showed that O-antigen was retained in salmonella after long starvation and transfer into an unculturable state.

Culture Media↗
PubMed1999

[Mechanism of ovarian follicle selection for ovulation].

Mechanisms of ovarian follicles selection for ovulation remain incompletely deciphered. Studying mechanisms of transmission of hormonal stimulatory and inhibitory signals to follicular histion somatic cells may assist in progress in this area of knowledge. The present study was aimed to detect a-subunits of G proteins (common, stimulatory, inhibitory) involved in transmission of hormonal signals to intracellular effectors and phospholipase C, initiating phosphatidyl inositol mechanism of hormonal stimuli transmission, in cryostat sections of follicles using indirect immunolabeling. A-common subunit to labeling index of granulosa layer cells correlating with the phase of follicle development was identified. A direct relationship between phospholipase C activity in granulosa layer cells of antral follicles and their size was demonstrated as well. The perspective of research in this area and their significance for the development of the theory of follicle selection is discussed.

Animals↗
PubMed1998

[Ultrastructural and immunocytochemical study of Listeria monocytogenes with varying levels of pathogenicity factor production].

Wild and mutant strains of Listeria monocytogenes are examined by electron and immunoelectron microscopy. The mutant strain was characterized as a strain with a high level of production of pathogenic factors. No essential morphological criteria permitting the differentiation between wild and mutant Listeria strains were detected. Addition of activated charcoal to nutrient medium resulted in similar morphological changes in both strains. Enlargement of cells, a thicker cell wall, and changes in the cytoplasm structure are objective morphological signs of functional activity of bacteria with a higher level of pathogenic factor production. Indirect immunocytochemical method demonstrated the localization of specific phosphatidyl inosityl phospholipase C.

Bacterial Proteins↗
PubMed1997

Glutathione status of placentae from differently polluted regions of Ukraine.

A study of the glutathione status as a prerequisite of the detoxifying activity of the fetoplacental barrier was undertaken in different regions of the Ukraine that have been judged either 'clean', chemically polluted or radioactively contaminated with different summary effective equivalent annual expositional doses (SEEAED). In the samples from clean regions, cytosolic glutathione transferase (GST), glutathione reductase (GSSG-R) activities and contents of total SH-groups were higher than in contaminated areas and corresponded to 50.4 +/- 9.0. 13.6 +/- 1.8 mU/mg cytosolic protein and 30.2 +/- 5.7 mumol/g tissue, respectively. In heavily radioactively exposed women, e.g. 'liquidators' (SEEAED in 1986: > 5 mSv), low GST activity, 17.0 +/- 3.0 mU/mg cytosolic protein and high malonic dialdehyde concentration, 128.8 +/- 13 nmol/g tissue were found; the latter serves as a measure of lipid peroxidation. In the placental specimens from heavily exposed women, the distribution of GST pi-specific antigen along the villi was irregular and differed from specimens of unexposed women. Malonic dialdehyde concentrations in all other groups of women were in the range 37.1-69.2 nmol/g tissue. In less exposed women, e.g. Kiev citizens and those from some rural areas (SEEAED in 1986: 4.9 and < 1 mSv, respectively), GST activity, 19.1 +/- 2.1 and 33.7 +/- 5.0 mU/mg cytosolic protein, increased concomitantly with the total content of SH-groups, 7.4 +/- 1.0 and 15.3 +/- 1.6 mumol/g tissue, and with the decreasing values of the first year SEEAED. GST activity, 49.6 +/- 8.8 mU/mg cytosolic protein, and total SH-group content, 19.8 +/- 0.5 mumol/g tissue, were even higher in the women evacuated on the second day after the catastrophe. Placental GST activity in chemically exposed women. 18.0 +/- 2.0 mU/mg cytosolic protein, was in the range of the lowest obtained values but the differences in the placental glutathione status between radioactively contaminated and chemically polluted areas point to different pathogenetic mechanisms of this reduction. The inverse correlation between the mean values of GSSG-R activities and the concentration of low-molecular weight thiols appears to be true for all groups. The indices of the placental glutathione status seem to be sensitive to environmental pollution.

Adult↗
PubMed1995

Ultrastructure of circulating immune complexes isolated from the blood plasma of patients suffering from infectious diseases.

An original procedure which permits to isolate circulating immune complexes (CIC) from the blood plasma in a form of a dense pellet was developed. This procedure was applied for the ultrastructural analysis of CIC isolated from blood of healthy blood donors and patients suffering from Yersinia enterocolitica (YE) and Yersinia pseudotuberculosis (YP) infections. The here reported method of CIC isolation from blood plasma permitted to visualize CIC electronmicroscopically as amorphous masses of low, middle, and high electron density with inclusions of cell debris. In contrast to CIC of healthy blood donors, CIC of infected patients contained various bacteria and fungiformic structures. For the first time, this method made possible an ultrastructural demonstration of bacterial destruction outside of phagocytes in vivo. This method also permits to visualize and identify bacteria in cases of lingering forms of infection when hemoculture tests fail. Therefore, electronmicroscopic examination of CIC preparations from the blood plasma might be a very informative indicator of bacteriemia in the course of an infection process and serve as an indicator of therapeutic effects. In lingering forms of an infection process, ultrastructural analysis of CIC preparations can be of prognostic value and serve as an indicator of therapeutic effects. This method might be also advantageous as an additional test for the exposure of latent bacterial persistence in diagnostically complicated cases.

Antigen-Antibody Complex↗
PubMedDate not supplied

[The ultrastructural characteristics of Francisella tularensis interaction with Tetrahymena pyriformis].

The electron-microscopic study of the interaction of F. tularensis virulent and attenuated strains with infusoria of the species T. pyriformis was dynamically studied. In this study the structural changes of F. tularensis and T. pyriformis cells, as well as their capacity for survival, were revealed. The data on their ultrastructure correlated with the dynamics of the number of both F. tularensis and T. pyriformis: during the whole term of observation the tendency to a slow decrease in the number of F. tularensis was registered with the concentration of T. pyriformis remaining stable. The interaction of F. tularensis with T. pyriformis may be regarded as a variant of commensal, but not antagonistic interactions.

Animals↗
PubMedDate not supplied

[Ultrastructure of Yersinia pseudotuberculosis in the process of their reversible transition into the dormant (non-culturable) state in association with blue-green algae].

The ultrastructural organization of Y. pseudotuberculosis in the process of the transition of vegetative cells into the dormant (noncultivable) state in interaction with blue-green algae of the species Anabaena variabilis was studied by the method of transmission electron microscopy. The use of type specific Y. pseudotuberculosis serum made it possible to identify Y. pseudotuberculosis cells in the bacterial association and to find out whether their antigenic properties remained intact in time. The dormant forms of Y. pseudotuberculosis, recultivated by passage through the axenic culture of unfusoria (Tetrahymena pyryformis), were also studied with the use of electron microscopy. The revertants were found to be at different stages of restoration of their typical morphological characteristics and antigenic properties were partially retained. The fine structure of Y. pseudotuberculosis cells in the initial culture was shown to be similar to that of the revertants of dormant forms, morphological criteria of the dormant cell ultrastructure were established. The cyclic processes of reversible transition from vegetative forms to dormant ones in bacterial populations under the influence of hydrobios is regarded as an adaptive mechanism of their existence in the environment.

Adaptation, Physiological↗
PubMedDate not supplied

[Evolution of epidemiology].

The emergence, formation and stages of the development of today epidemiology of infectious diseases are analyzed. Differences in views concerning the essence of epidemiology as science between Russian and foreign schools are indicated. The brief description of the main stages in rendering basic concepts of Russian epidemiology more extensive and profound, including the gradual alteration of the view on epidemiology as the science dealing only with the epidemic process, is presented. In this connection new data on the epidemiological specificity of zoonotic, and especially sapronotic infections, leading to an essenmtal correction of the main postulates of epidemiology, are analyzed. Broader notions of the reservoirs of the causative agents of infections are given, the discrete character of the epidemic (epizootic) process, the role of the latent forms of bacteria in their preservation both in the environment and in the human body in the course of the infectious process are postulated. The complexity of the term "emerging infections" is discussed and 3 variants of its interpretation are proposed. The increasing role of anthropogenic factors, including technogenic effects, is emphasized; in future these factors may be capable of accelerating the man-made evolution of epidemiology.

Animals↗