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Biomedical subjects

A L Gintsburg

Publications and source records attributed to A L Gintsburg.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

[Quantitative PCR-analysis: development of a system for determining the level of an amplified DNA fragment].

A new technique is elaborated for quantitative evaluation of the polymerase chain reaction (PCR) results based on a system for yopA gene identification in Yersinia pseudotuberculosis fragment located on p45 plasmid. The analysis schedule includes amplification of the studied DNA sequence under the conditions when the reverse primer carries chemically bound biotin label on the 5'-end, hybridization of the labelled amplified fragment with the probe immobilized on the microplate surface, the probe being complementary to the inner portion of specific DNA, visualization of the label, and calculation of bound labelled DNA quantity. The lower threshold of analysis sensitivity is some picograms. It makes possible the analysis and detection of PCR product in the period of exponential increase of its content, i.e. in the initial period of reaction when the quantity of amplified DNA in the reaction mixture is not enough for reliable identification by ethidium bromide staining.

Bacterial Outer Membrane Proteins↗
PubMedDate not supplied

[The isolation of Vibrio cholerae strains that produce cholera toxin and its B-subunit].

The creation of two V. cholerae strains, belonging to the classical biovar, serovars Ogawa and Inaba, and serving as hyperproducers of cholera toxin, is described. The strains have been created by means of recombinant plasmid pCO107-2, carrying the cloned gene of cholera toxin vctAB. The use of recombinant plasmid pIEMZ3 carrying the cloned gene of the B-subunit of cholera toxin vctB has made it possible to obtain a strain, capable of producing the B-subunit of cholera toxin, on the basis of V. cholerae strain non 01. Besides, V. cholerae isogenic toxigenic strains, serovars Inaba and Ogawa, with the increased production of the B-subunit of cholera toxin, have been obtained.

Animals↗
PubMedDate not supplied

[The use of a polymerase chain reaction method for the diagnosis of Mycoplasma pneumonia].

The assay system for the diagnosis of Mycoplasma pneumoniae infections, based on polymerase chain reaction (PCR), has been developed. The sensitivity of the detection of M. pneumoniae DNA in analysis of different clinical samples has been established. The study has shown the possibility of using the newly developed assay system for the detection of M. pneumoniae in the material obtained from patients with atypical forms of pneumonia and from Mycoplasma carriers.

Adult↗
PubMedDate not supplied

[Development of a test system for detecting Leptospira interrogans using the polymerase chain reaction].

Based on polymerase chain reaction a test-system has been elaborated permitting one to identify the leptospirae of the most common serogroups (Icterohaemorrhagiae, Canicola, Javanica, Ballum, Pyrogenes, Pomona, Habdomadis, Sejroe, Tarassovi) of the species Leptospira interrogans. Sensitivity of the technique is 1-10 cells in a sample. The specificity of the system has been shown to depend on the temperature of the primers annealing. The elaborated system exceeds all other systems for leptospiral identification in sensitivity. It is prospective for leptospiral identification in biological liquids aimed at early diagnosis of leptospiroses and in the studies of leptospiral persistence in host organisms in the saprophitic phase of life cycle.

DNA Primers↗
PubMedDate not supplied

[A polymerase chain reaction method for studying host persistence of pathogenic leptospira].

Polymerase chain reaction has for the first time been shown to be applicable to indication of Leptospira interrogans in the organs of infected animals with acute or chronic leptospirosis (on the model of golden syrian hamsters). Polymerase chain reaction is superior to microscopic and bacteriological analyses in identification of leptospirae in organ suspensions. The sensitivity of the technique is 1-10 cells per sample in studies of kidney or brain suspensions or 100-1000 cells in studies of liver suspensions.

Acute Disease↗
PubMedDate not supplied

[Use of the polymerase chain reaction for studying the processes of Salmonella typhimurium cells to an noncultivated state].

The possibility to identify noncultivating forms of Salmonella by the polymerase chain reaction (PCR) has been shown. To do it the technique for Salmonella identification was elaborated, based on amplification of a 500 bp fragment of araC gene. Time course of populations of two Salmonella typhimurium strains during prolonged incubation in water was studied by the techniques of serial dilutions on solid nutrient media, acridine orange staining, and PCR. The strains differed in pathogenicity levels and genetic characteristics. Cells of nonvirulent strain were shown to loose gradually in the process of incubation the ability to grow on solid nutrient media and transform into noncultivating forms whose ability to proliferation can be restored under definite conditions. No difference in the dynamics identified by PCR or traditional microbiological techniques was found for population of virulent Salmonella typhimurium incubated in water indicating the possibility of fast degradation of cells having lost the ability to divide.

Base Sequence↗
PubMedDate not supplied

[A possible mechanism for the endemicity of modern cholera (the role of noncultivated forms of Vibrio cholerae 01)].

The surface water sources of some CIS territories have been screened for cholera toxin genes by the polymerase chain reaction. The vct-genes have been found in the majority of water samples indicating the presence of noncultivated vibrio cholerae cells of an epidemiologic significance. The bacteriological methods failed to isolate the active causative agent of cholera. Additional criteria are proposed for epidemiological typing of territories for cholera. The absence of long deletions or insertions in the vct-genes of noncultivated cholera vibrios has been shown in comparison with analogous gene of the active causative agent of cholera.

Base Sequence↗
PubMedDate not supplied

[Study of genomic polymorphism of Shigella flexneri strains, isolated in various geographic regions].

Strains of Shigella flexneri isolated from patients in 4 geographic regions of the former USSR have been studied by plasmid analysis and fingerprinting techniques. It has been shown that these methods make possible to differentiate phenotypically identical strains for 9 genotypic patterns (7 different plasmid profiles and 3 specific hybridization patterns). Strains of Shigella flexneri isolated from each region possess the similar hybridization patterns independent of serovar and plasmid profiles. Similar hybridization patterns were found among the strains isolated in Erevan and Dushanbe. The strains isolated in Kiev are related to Erevan and Dushanbe strains, but they also possess the specific additional hybridization bands. Tashkent isolates are different from the strains isolated in other geographic regions. They are also of clonal origin in spite of the different serovars and plasmid profiles registered for these strains. Positive correlation has been found between serovar and plasmid profile characteristics of the strains. The clonal origin of the Tashkent isolates is different from the one of Erevan, Dushanbe and Kiev isolates, the latter having a similar clonal origin.

Genes, Bacterial↗
PubMedDate not supplied

[Genetic control of the induction of a nonculturable state in pathogenic bacteria].

The laboratory model for the induction of nonculturable forms in Salmonella typhimurium has been developed. S. typhimurium mutants with disturbances at different stages of their transfer from vegetative to nonculturable state have been obtained by insertion mutagenesis with the use of TnPhoA transposon. To identify the functions of genes involved in the process of the appearance of nonculturable forms, their cloning in the sequencing vector has been carried out.

Animals↗
PubMedDate not supplied

[Molecular genetic approaches to the study of the persistence of pathogenic Mycoplasma].

The inhibition of the amplification of different regions of Mycoplasma pneumonia genome, depending on the conditions of cultivation, was observed with the use of polymerase chain reaction. A protein, stably associated with DNA, is responsible for this inhibitory effect. When selectively associated with different sites of DNA, the protein seems to be capable to inhibit the expression of genes, encoding pathogenicity factors of mycoplasmas and thus promoting their transformation into persistent forms.

Animals↗
PubMedDate not supplied

[Genomic polymorphism in Mycobacterium tuberculosis strains].

Different genomic fingerprinting techniques (universal probes, such as rRNA genes, phage M13 DNA, IS 6110 probe) have been used to investigate the genomic polymorphism of Mycobacterium tuberculosis strains isolated in different geographical regions of Russia and in some CIS countries. As shown with the use of these techniques and a specially developed PCR-mediated system for genetic typing, M.tuberculosis strains are genotypically heterogeneous in regions with a sporadic level of tuberculosis morbidity and genotypically homogeneous in regions with elevated morbidity and mortality levels. The evaluation of the effectiveness of the genetic typing of M.tuberculosis with the use of different genomic fingerprinting techniques has made it possible to propose the optimum 3-stage scheme for the differentiation of M.tuberculosis strains: (1) the typing of all isolated strains of the PCR-mediated test system; (2) the typing of several selected M.tuberculosis strains with the use of 1S 6110 probe (2-3 strains of each detected PCR-RFLP [correction of PLRF] genotypes); (3) the typing of M.tuberculosis strains, containing 1 copy of 1S 6110 or not containing such sequence, with the use of probes (phage M13 DNA) detecting hypervariable sequences in M.tuberculosis genomes.

Bacterial Typing Techniques↗
PubMedDate not supplied

[Transfer of S. typhimurium strains with mutation to a noncultured state, disrupting synthesis of purine bases].

Effects of mutations impairing the synthesis of purine nucleotides on the process of S. typhimurium cells transfer into an unculturable state (US) have been studied. The presence of guaA- mutation in the cells was found to lead to a sooner transfer to US in comparison with the cells of reference strain. The presence of purE- mutation does not tell on the rate of mutant cells transfer in US.

Adenine↗
PubMedDate not supplied

[Nonculturable forms of Yersinia pseudotuberculosis in the soils of a natural focus of pseudotuberculosis].

Soil samples taken from the natural focus of pseudotuberculosis, characterized by the persistent presence of Y. pseudotuberculosis, were studied. Bacteria were detected by means of polymerase chain reaction with the use of 2 test systems; one of them was specific to the chromosomal invasiveness gene (inv) and the other, to gene yopA, localized on plasmid pCad. In 10 out of 24 sample of genetic material of the total soil microflora, Y. pseudotuberculosis gene inv was detected, two of these samples being also containing gene yopA. The calculated concentration of Y. pseudotuberculosis varied 10(2)-10(4) microbial cells per 1 g of soil. Bacteriological studies yielded negative results, which is indicative of the existence of Y. pseudotuberculosis in the soil of the natural focus in the nonculturable form.

DNA, Bacterial↗
PubMedDate not supplied

[Pathogenic Listeria in the soil and in association with algae: a reversible transition into a nonculturable state].

The analysis of the dynamics of the amount of L. monocytogenes in soil extract in association with green algae and in their absence, carried out in parallel by the bacteriological method and in polymerase chain reaction (PCR), revealed the mass transition of L. monocytogenes into the nonculturable state. The proportion of vegetative (bacteriologically detected) forms in the bacterial population rapidly decreased, while its total amount remained unchanged due to the formation of inactive (nonculturable) L. monocytogenes forms. Algae or their metabolites considerable accelerated this process: by day 26 L. monocytogenes could not be isolated, but in PCR they could be registered at their initial concentration: 10(6) microbial cells/ml. Inactive L. monocytogenes forms were shown to revert into the vegetative (culturable) state under the action of fetal serum, live and killed infusoria, auxin. The concentration of revertants grown on a solid culture medium was high: 10(4)-10(5) colony-forming units/ml.

Bacteriological Techniques↗
PubMedDate not supplied

[The nonculturable state in pathogenic bacteria modelled on Salmonella typhimurium: the phenomenon and its genetic control].

The data on the influence of mutation in genes, affecting vital functions of a bacterial cell, on the process of transition into the nonculturable state in S. typhimurium are presented. Four genes obtained by the authors have been identified. Mutations in these genes lead disturbances in the formation of S. typhimurium nonculturable forms. The nonculturable forms of salmonellae have been shown to retain their virulent properties and their capacity for recultivation, when inoculated into laboratory animals.

Base Sequence↗