[The genome polymorphism of Vibrio cholerae ctxAB(-) strains, containing the proximal part of the CTX element]. / Izuchenie genomnogo polimorphizma ctxAB(-)-shtammov kholernykh vibrionov, soderzhashchikh proksimal'nuiu chast' CTX-elementa.

The comparative analysis of the hybridization patterns of DNA restricts for 20 V. cholerae, groups 01 and non-01 (non-0139), containing the incomplete CTX element (ctxAB-) was carried out with the use of probes, complementary to the genes of the proximal part of the virulence cassettle and flanking its RS1 sequences. This group was found to be heterogeneous both in the number of copies of "truncated" CTX prophage and their localizations in the genome, as well as in the position of the sites of restriction endonucleases HindlII and BglII. Among 17 clinically noncholerigenic isolates, 5 etiologically dangerous clones were found, each of them characterized by the definite time and place of isolation. At least one of them proved to be the causative agent of the local outbreak of diarrheal diseases in Uzbekistan.

[Effect of various amino acids and ammonium salts in a synthetic culture media on the cholera enterotoxin production]. / Vliianie razlichnykh aminokislot i solei ammoniia v sostave sinteticheskoi pitatel'noi sredy na produktsiiu kholernogo énterotoksina.

The influence of amino acids and ammonium salts on the production of cholera enterotoxin (CT) by 3 Vibrio cholerae strains of different biovars and serogroups was evaluated. As revealed in this study, toxin formation in each of the strains was quantitatively and qualitatively determined by their individual sets of amino acids. The amino acid compositions ensuring the maximum production of CT by the V. cholerae strains under study were formed. The use of ammonium salts as the only source of nitrogen in the composition of a synthetic nutrient medium for the accumulation of CT was shown to be inexpedient.

[Analysis of toxin genetic determinants of Vibrio cholerae virulence cassette and neuraminidase with DNA probes]. / Izuchenie geneticheskikh determinant toksinov kassety virulentnosti i neiraminidazy kholernykh vibrionov s pomoshch'iu molekuliarnogo zondirovaniia.

V. cholerae strains of different origin have been studied for the presence of cholera toxin genes (vct), the proximal part of the virulence cassette including genes zot, ace and orfU, as well as neuraminidase genes (neu), in their genomes with the use of molecular DNA probes. The possibility, in principle, for some strains to lose only a part of their virulence cassette (gene vct), while retaining its proximal part has been shown. In most cases such strains are isolated from patients with diarrhea of different severity and may probably play some etiological role, provided that the expression of the genes of additional toxins of the virulence cassette occurs. The gene expressing neuraminidase which facilitates the penetration of cholera toxin into the epithelial cells of the intestine is always present in vct+ strains and may be absent in vct- strains. The absence of genetic relationship between neuraminidases in V. cholerae O139 and V. cholerae O1 and non-O1 (non-O139) has been confirmed. The problems in connection with the integration and deletion of genetic determinants of V. cholerae virulence factors are discussed.

[The evaluation of the virulent properties of Vibrio cholerae O1 by using in-vitro methods]. / Otsenka virulentnykh svoistv Vibrio cholerae O1 s pomoshch'iu metodov in vitro.

The virulent properties of V. cholerae O1 (more than 1000 strains) were studied. For this purpose the following methods were used: the determination of hemolytic activity, the express method based on the determination of the speed of mannite oxidation, complex analysis and polymerase chain reaction (PCR). The comparative analysis of the results of the in vitro determination of virulence revealed that the most frequently occurring strains among the strains isolated from humans were vct+ strains (80.5%), hemolysis-negative strains (83.9%) which were virulent (faintly virulent) as determined by complex analysis (38.2%), cholerogenic as determined by the express method (60.2%). Among the strains isolated from the environment were vct- strains (87.4%), hemolysis-negative strains (63.2%) which were virulent as determined by complex (13.1%), as well as by the express method (74.3%). The data of the determination of the vct gene did not correlate with the results obtained by complex analysis. The use of complex analysis was expedient only in the detection of strains sensitive to eltor phage in the dilution routine test of V. eltor strains. The methods for the determination of virulence, available for practical laboratories, were Grieg's method for the determination of hemolytic activity and express method. PCR proved to reliable in vitro method for the determination of the vct gene.

[Genetic determination and the spectrum of the hemolytic activity of Vibrio cholerae: their significance in the complex of biovar-specific traits]. / Geneticheskoe determinirovanie i spektr gemoliticheskoi aktivnosti Vibrio cholerae: znachenie v komplekse biovarospetsificheskikh priznakov.

A collection of 363 V. cholerae strains isolated from different sources were studied by the spectrum of their hemolytic activity in combination with biovar-associated properties. The strains were analyzed for the presence of the cholera toxin (CT) gene (vct) and the hemolysin gene (hly) with the use of the CT probe and a previously cloned 6.56 kb fragment of V. eltor DNA coding the synthesis of hemolysin. The study revealed that all V. cholerae strains had the hly gene irrespective of the spectrum of their hemolytic activity, biovar, 01 agglutinability and the presence of the vct gene in their genome, while other species of the genus Vibrio and related groups contained no hly gene sequence. The results of the comparative study of the hemolytic activity of V. cholerae and V. eltor are discussed.

[Species specific DNA probes for identifying Vibrio cholerae]. / Vidospetsifichnyi DNK-zond dlia identifikatsii kholernykh vibrionov.

A 1.74 kb HindIII fragment from a Vibrio cholerae eltor library of genes was found to be strictly specific for Vibrio cholerae strains independent of the biotypes, serotypes and 01-agglutination ability. The fragment was cloned in pUC19 vector plasmid. The resultant recombinant plasmid pES78VCS was transformed into Escherichia coli strain HB101 resulting in construction of strain KM57. The sites for HincII and XhoI were plotted on a restriction map of the cloned fragment. Two HindIII-XhoI as well as one HincII-XhoI fragments appeared to be of the same specificity as the intact HindIII-HindIII one. The probe identifies 10(6) bacterial cells or 60 ng of purified chromosomal DNA of Vibrio cholerae and may be used for identification of 01 and non-01 strains.

[Distribution of lipids and lipolytic activity between the solid and liquid phases of an enteral medium]. / Raspredelenie lipidov i lipoliticheskoi aktivnosti mezhdu plotnoi i zhdikoi fazami enteral'noi sredy.

Data on the lipid and lipase activity distribution between the solid and liquid phases of the enteric coacervate formed from pancreatic secretion at lower pH is described. It is established that after coacervation the amount of lipids available for extraction increases, the lipase activity of sample grows, the major part of the lipase activity becomes localized in the solid phase. The solid phase is rich in lipids, the content of which pH dependent. A hypothetical mechanism of these phenomena and some computations are presented.

[Role of the enterohepatic circulation of endogenous lipids in food lipid absorption]. / Rol' pechenochno-kishechnoi tsirkuliatsii éndogennykh lipidov vo vsasyvanii lipidov pishchi.

In preliminarily operated dogs with fistulas in stomach and different portions of the small intestine, the liver-intestinal circulation of endogenous phospholipids and cholesterine aided to form the chimus all the lipid fractions of which were absorbed proportionally. The recirculation of endogenous lipids seems to be one of the physiological mechanisms of lipid absorption from food in the small intestine.

[Homeostatic influence of the lipid composition of the chyme and the effect of the correlation of basic lipid classes on the intensity of their absorption in the small intestine]. / O gomeostazirovanii lipidnogo sostava khimusa i vliianii sootnosheniia osnovnykh klassov lipidov na intensivnost' ikh vsasyvaniia v tonkoi kishke.

Experiments on normal unanesthetized polyfistulous dogs kept on a mixed diet were made to study the basal lipid ratios of the duodenal and small intestinal chyme. It was shown that the duodenal and small intestinal chyme underwent homeostasis as regards the basal lipid class at the expense of the adding endogenous lipids to digestive juices. The ratios mentioned did not change substantially as a result of lipid absorption during exposure of the chyme in an isolated part of the intestine. The data obtained suggest that the rate of lipid absorption depends on the lipid profile of the chyme.