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Biomedical subjects

I S Tartakovskiĭ

Publications and source records attributed to I S Tartakovskiĭ.

At least 19 recordsLinked to original sources
PubMed2005

[The contribution of system regulation of pathogenicity-determining genes expression to the virulence of facultative intracellular parasites].

Bacteria which belong to the group of facultative parasites are capable of intensive proliferation both outside the organism and inside eukaryotic cells, thus often causing severe human and animal illness. The necessity of quick adaptation to the alteration of conditions after intrusion into the macro-organism gave rise to the development of complex genetic systems, regulating the activity of various gene groups. The review, written by the example of two pathogen bacteria, the gram-positive Listeria monocytogenes and the gram-negative Legionella pneumophila, illustrates up-to-date data that concern system regulation of genes, coding pathogenicity factors, as adaptive response of a bacterium to changes in outer conditions within the infectious process.

Animals↗
PubMed2005

[A new complex approaches for the identification of Listeria isolated during production of fermented sausages].

Distribution L. monocytogenes and other Listeria spp. in raw meat and during manufacturing of fermented meat products is investigated. The high contamination of raw materials and semi finished foods--in 36.5% of samples, ready-to-eat sausages--31.8% by Listeria spp. is established. Detection L. monocytogenes in 9.7% cases from the surfaces of equipment indicates the intensive circulation of listeriosis agents on meat plants. For identification 49 isolated strains the approach providing application of most informative for L. monocytogenes phenotypical tests (mobility, ability to haemolysis, presence of specific lecithinase) and assay based on PCR of DNA sites, coding phospholipase, factors of invasion and citotoxicity is used. Efficiency of this circuit is confirmed with positive results PCR with species-specific for L. monocytogenes primers to genes PIcA and ActA only at strains, having lecithinase and haemolysis activity. Application of the given approach has allowed to reduce in three times number of the cultures initially identified as L. monocytogenes on a complex of biochemical tests.

Colony Count, Microbial↗
PubMed2005

[Different species of Legionella plasmids and virulence].

Plasmids with a molecular weight of 2.5 to 80 MD were shown to be present in a significant portion of different-type Legionella strains including high-virulence isolates L. pneumophila, serogroup 1, and L. bozemanii detected both in Russia and abroad in different sources. Plasmid-free derivative were obtained from the L. pneumophila strains each carrying only one different-size plasmid DNA. The variants had the same virulence as the original cultures for chicken embryos and guinea pigs, when the latter were infected in the bile sac or through intraperitoneal routes, respectively; their virulence was also similar to that of strains resistant to the normal serum of guinea pigs. Hence, the infection models used by us failed to show any action of plasmids on the virulence of Legionella.

Animals↗
PubMed2001

[Legionnaires disease: results of 25-years of studying infections, problems and perspectives of research].

The paper summarizes the results of 25-year study of Legionnaires' disease (Legionnaire's bacillus infection) in its epidemiology, diagnosis, and prevention, the taxonomy and biology of the causative organism. Emphasis is laid on the contribution of the Russian school of investigators in studying this problem. Despite the intensive efforts in investigating the infection and its causative organism, there are still many problems in predicting and preventing the epidemics of Legionnaires' disease, which annually occur in different countries of the world. Legionnaires' disease is a typical example of technogenic infections: active industrial and domestic uses of closed water circulating systems in industry and aerosol sources promote the spread of the infection caused by Legionnaire's bacillus and make its control in these systems. Despite the introduction of current immunological and molecular genetic methods, diagnosis is effective only for L. pneumophila, serogroup 1. The sensitivity and specificity of methods for diagnosis and identification for other 15 L. pneumophila serogroups and 41 species of L. bacilli are far from being perfect. L. bacilli are also a most popular object for studying the biochemical and genetic aspects of its intracellular parasitism.

Humans↗
PubMed2000

[Changes in the virulence factor expression level in Listeria monocytogenes under various environmental conditions].

Effects of chelators Chelex-100 and activated charcoal on the production of proteins responsible for virulence of Listeria monocytogenes, facultative intracellular parasite were studied. Bivalent cation chelator Chelex-100 stimulates the production of only thiol-dependent hemolysin listeriolysin O. The presence of activated charcoal, a nonspecific chelator, in culture medium stimulated the expression of listeriolysin O and other main virulence factors by increasing the level of their transcription.

Bacterial Proteins↗
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↗
PubMed1991

[A mathematical model of the growth of a population of Legionella pneumophila in the presence of Tetrahymena pyriformis protozoa].

The mathematical model describing the dynamics of the growth of L. pneumophila in aqueous environment in the presence of protozoa has been worked out. The model has demonstrated considerable heterogeneity of the initial population of virulent L. pneumophila strains. The number of bacteria capable of multiplication in Infusoria is no more than 0.1% of the initial population. The time of the generation of the infective agent inside Tetrahymena pyriformis is 2.8 hours.

Animals↗
PubMed1991

[The effect of interferon preparations on the ultrastructural organization of Legionella pneumophila].

The influence of the preparations of interferon on morphological changes in L. pneumophila on the ultrastructural level has been studied. Disturbances in the ultrastructure of L. pneumophila result from the direct bactericidal action of interferons without any interference of immune mechanisms. These disturbances are manifested by damages in the cell wall, plasma membrane, nuclear and ribosomal apparatuses of microbial cells. Leukinferon exhibits pronounced anti-Legionella activity, both in vitro in a liquid culture medium and in ovo, than reaferon.

Animals↗
PubMed1991

[A method for the passive agglutination of polymer dispersions for the diagnosis of legionellosis].

The method of synthetizing dispersions of gelatin-modified polyacrolein microspheres 1.5-2.5 micrograms in diameter, used as a solid-phase carrier for the preparation of immunodispersion diagnostica, has been developed. The possibility of using immunodispersion diagnosticum in the passive agglutination test with hyperimmune rabbit sera has been demonstrated. High activity and specificity of immunodispersion diagnosticum, combining methodological simplicity and rapidity characteristic of agglutination, has been shown.

Agglutination Tests↗
PubMed1991

[The typing of Legionella pneumophila strains by using monoclonal antibodies to the cytolysin].

Studies on the typing of L. pneumophila strains of serogroup 1, isolated from patients and environmental objects, have been made with the use of monoclonal antibodies (McAb) to cytolysin. The results of the comparison of the specificity of our McAb with that of a commercial set McAb obtained from the USA make it possible to recommend preparations based on McAb to cytolysin for the detection of L. pneumophila pathogenic strains of serovar 1. The use of FITC- and peroxidase-labeled McAb to cytolysin permits the reduction of the time necessary for the diagnosis of Legionella infections and the detection of the antigen in a dose of 10 ng/ml.

Antibodies, Monoclonal↗
PubMed1991

[The interaction of Legionella pneumophila with different types of cell cultures and the effect of interferon preparations on this process].

The interaction of L. pneumophila with lymphoblastoid cell cultures H9 and H9/IIIB and epithelial cell cultures HEp-2 mutual influence have been noted. L. pneumophila penetrates into cells HEp-2 and multiplies there due the so-called "spin phagocytosis". The study of the influence of the preparations of interferon, Leukinferon and Reaferon, on the adhesive capacity of bacteria and their penetration into eukaryotic cells has revealed that the preliminary treatment of both bacteria and cells HEp-2 with the preparations of interferon prior to their infection with Legionella leads to a decrease in the number of microorganisms associated with cells.

Bacterial Adhesion↗
PubMed1991

[The genomic fingerprinting of the causative agents of sapronoses].

The genome polymorphism of the causative agents of sapronoses (Vibrio cholerae, Legionella and Leptospira) has been studied. The use of the method of genome fingerprinting [correction of dactyloscopy] has been shown to permit the differentiation of closely related strains of such causative agents. The epidemically significant strains of the causative agents of sapronoses, isolated in different geographical regions, have been found to be genotypically related, i.e., they are probably of clonal origin. Avirulent and nontoxigenic strains are genotypically heterogeneous and differ both from one another and from epidemically significant strains. Using V. cholerae as an example, the hypothesis of the appearance of potentially dangerous variants at the epidemic period in the absence of their release at the period between epidemics is considered.

DNA Fingerprinting↗
PubMed1991

[The ultrastructural characteristics of the interaction of Legionella pneumophila with the infusorian protozoon Tetrahymena pyriformis].

In this work the morphological features of the interaction of L. pneumophila virulent strain and T. pyriformis have been studied on the submicroscopic level in the time course of the process. The study has shown the process of the destruction of the bacterial population and the penetration of individual intact Legionella cells from the phagosome into the endoplasm of T. pyriformis after 6-9 hours of interaction in the form of the budding of the phagosome and further multiplication of Legionella in the endoplasm. As revealed in this study, T. pyriformis have two types of phagosomes characterized by different variants of the destruction of Legionella. In T. pyriformis lysosomes-like granules, mitochondria and the granular endoplasmatic network take part in the process of interaction. The process of interaction has been found to end by day 7 in the death of all protozoal cells taking part in interaction.

Animals↗
PubMed1991

[The splitting of the acceptor proteins of the protein kinase system in eukaryotic cells by Legionella cytolysin].

In the process of protein kinase reaction carried out in the mixture consisting of tris-HCl buffer, EDTA, MgCl2, gamma-32P-ATP and the cytoplasmic fraction of rabbit pulmonary cells the phosphorylation of proteins with molecular weights of 150 and 55 kD took place. The addition of L. pneumophila culture fluid to the reaction mixture resulted in the splitting of phosphorylated proteins with the formation of the component having a molecular weight of 45 kD. These disturbances in protein kinase reaction were found to occur due to the involvement of Legionella cytoplasm, a previously characterized protein with a molecular weight of 37 kD, into the process. In this connection, the participation of cytolysin in the pathogenesis of Legionella infection may also be considered from the viewpoint of the effect produced by cytolysin on the regulatory processes affecting the metabolism of target cells.

Animals↗
PubMed1990

[The biological properties of monoclonal antibodies to the cytolysin of Legionella pneumophila].

The study of the biological properties of monoclonal antibodies (McAb) to L. pneumophila cytolysin has been carried out. These McAb have been shown to possess no capacity for the in vitro neutralization of cytolysin and the protection of guinea pigs from aerosol infection with L. pneumophila. Still the protective effect of the McAb under study has been observed in experiments with the intraperitoneal infection of guinea pigs, which is indicative of the possibility, in principle, of involving humoral immunity into the protection of the body from Legionella infection.

Administration, Intranasal↗