[Differential gene expression in culturable and non-culturable Salmonella typhimurium]. / Differentsial'naia ékspressiia genov v kul'tiviruemykh i nekul'tiviruemykh formakh Salmonella typhimurium.

Differential gene expression in culturable and non-culturable forms of Salmonella typhimurium was studied by the molecular display method. Six fragments of differentially expressed gene cDNA, depending on culturable or non-culturable state of the cultures, were isolated, cloned, and sequenced. Identification of corresponding S. typhimurium differentially expressed genes was carried out by comparing the sequences of cDNA fragments with the bacterial genome data base.

[Mechanisms of activation of pathogenic bacteria in the host organism]. / Mekhanizmy aktivatsii patogennykh bakterii v organizme khoziaina.

A minireview of the data of literature on the interaction of bacteria with cytokins and the stimulation of the growth of pathogenic bacteria by some cytokins is presented. The addition of tumor necrosis factor-alpha into the culture medium has been shown to stimulate the growth of Salmonella virulent and avirulent strains 4-fold and 2-fold respectively. This cytokin has also been shown to produce a stimulating effect on the process of the in vitro and in vivo recultivation of noncultivating forms of virulent and avirulent strains.

[Use of the polymerase chain reaction to identify Helicobacter pylori in clinical material]. / Primenenie polimeraznoi tsepnoi reaktsii dlia identifikatsii Helicobacter pylori v klinicheskom materiale.

A new system for the detection of Helicobacter pylori DNA, based on the method of directed amplification, has been developed. Primers for specific detection of H. pylori were selected from a nucleotide sequence of 16 S-p RNA. The sequences of the primers had a few nucleotide substitutions as compared with the sequences of closely related microorganisms. An essential condition for the attainment of reaction specificity was the rise of annealing step temperature to 66 degrees C. Sensitivity of the system was in the range of 3 to 30 fg of DNA, or 20 to 100 bacterial cells. Using the proposed system for the detection of H. pylori DNA clinical specimens (stomach biopsy sample, gastric juice and wash-offs of oral cavity), obtained from 49 patients with antral gastritis, were analyzed. The method of H. pylori detection in clinical specimens using polymerase chain reaction (PCR) turned out to be more sensitive compared with microbiological tests. By application of PCR H. pylori DNA was detected in subgingival pockets.

[Design of a chromosomal DNA probe species specific for Yersinia pestis]. / Konstruirovanie vidospetsifichnogo dlia Yersinia pestis khromosomnogo DNA-zonda.

A 14.8 kb DNA fragment from the chromosome of Yersinia pestis TWJ was cloned and the restriction map constructed. The fragment designated as T16 and its subfragments were tested in dot-hybridization with strains of Yersinia genus and other members of Enterobacteriaceae. A species-specific DNA probe (designated MK) was constructed on the basis of the T16 fragment. As judged from restriction analysis, blot-hybridization experiments and, partially, sequencing, significant homology exists between the MK DNA probe and this one developed by Bardarov et. al. (1990). A repeated sequence in two copies was discovered in the MK fragment.