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S Meshkov

Publications and source records attributed to S Meshkov.

13 recordsLinked to original sources
PubMed1999

The structures of the carbohydrate backbones of the lipopolysaccharides from Escherichia coli rough mutants F470 (R1 core type) and F576 (R2 core type).

The lipopolysaccharides (LPS) from Escherichia coli rough mutant strains F470 (R1 core type) and F576 (R2 core type) were deacylated yielding in each case a mixture of oligosaccharides with one predominant product which was isolated using high-performance anion-exchange chromatography. In addition, one oligosaccharide present in minor quantities was isolated from LPS of E. coli strain F576 (R2 core type). The structures of the oligosaccharides were determined by chemical analyses and NMR spectroscopic experiments. Furthermore, de-O-acylated and dephosphorylated LPS preparations were investigated by fast-atom bombardment and collision induced dissociation tandem mass spectrometry. The combined data allow us to deduce the following carbohydrate backbones of the E. coli R1 and R2 core types which share the following structure (Scheme 1): but differ in the substituents R1 and R2 which for the R1 core type are predominantly: and to a minor extent: and for the R2 core type predominantly: and to a minor extent: in which all sugars are d-pyranoses (l,d-Hep, lglycerodmanno-heptopyranose; P, phosphate).

Carbohydrate Conformation↗
PubMed1997

Structural investigation of the lipopolysaccharide from Acinetobacter haemolyticus strain NCTC 10305 (ATCC 17906, DNA group 4).

The structure of the lipopolysaccharide (LPS) from Acinetobacter haemolyticus strain NCTC 10305 (DNA group 4) was elucidated by means of analytical chemistry, NMR spectroscopy and fast-atom-bombardment mass spectrometry. Several oligosaccharides were obtained after deacylation or successive de-O-acylation, dephosphorylation, reduction, and de-N-acylation of LPS. In the major fraction of the LPS, the core is attached to the lipid A through D-glycero-D-talo-2-octulopyranosonic acid (Ko), whereas in a minor fraction (<20%) Ko is replaced by 3-deoxy-D-manno-octulopyranosonic acid (Kdo). The structures of the phosphorylated carbohydrate backbones of these LPS fractions are [structure: see text] with Dha = 3-deoxy-D-lyxo-2-heptulosaric acid, Sug = sugar and is Ko in a major fraction and Kdo in a minor fraction. All sugar residues have the D-configuration and are present in the pyranose form. Mass spectrometry of de-O-acylated LPS revealed the presence of an additional hexose residue in minor amounts, the position and nature of which could not be identified.

Acinetobacter↗
PubMed1981

[Immunobiological and antigenic studies of Babesia ovis strains in Bulgaria].

A comparative study was carried out on the immunologic and antigenic properties of 8 strains of Babesia ovis isolated in 5 districts of the country. The immunologic capacity was tested through challenging with each of the strains in group of 4 weaned lambs that were preliminary vaccinated with one of the strains - Veliko Turnovo. Two nonvaccinated animals were included in each group, serving as controls. The strength of immunity was checked by both the temperature and the parasitic reaction as well as through the hematocrit and hemoglobin levels of the challenged lambs. With the exception of one spleen - ectomized animal in each group the vaccinated weaned lambs showed solid immunity against both the homogeneous and heterologic strains. The same result was confirmed also with an analogous biologic experiment with a total of 19870 sheep in 28 enzootic foci in the same 5 districts and in 2 other districts of the country. Cross serologic investigations by means of the complement - fixation test, the agar gel precipitation reaction and IRPA with homologous and heterologous antisera revealed identic or close antigenic properties in the tested strains. In is concluded that the Veliko Turnovo strain can be used to prepare a vaccine for the immunoprophylaxis of babesiasis in sheep in the investigated districts. In is also stated that the serologic reactions, and, more specifically, IRPA can be employed in the antigenic study and differentiation of individual Babesia ovis strains.

Animals↗
PubMed1978

[Distribution of Sarcosporidia among wild animals in Bulgaria].

A total of 395 wild animals represented by 12 species have been studied over the 1972-1975 period for the presence of sarcosporidia--wild swine, does, hares, jackals, foxes, wild cats, polecats, rats, forest mice, and weasels killed in various regions of the district of Bourgas. Investigated were also several monkeys and wandering dogs. Samples were taken from the muscles of the neck abdomen, hind legs, gut, pharynx, chewing muscles, and hearts to study them for microcysts by the compression method. Sarcosporidia were established in 26.08% of the investigated animals of the following species: wild swine--66.76%, does--71.74%, hares--7.28%, rats--5.50%, and forest mice--10.0%. Most intensive proved parasitizing in does, hares, and swine, and least intensive--in rats and mice. Sarcocysts were found in all investigated viscera, highest being the parasite burden in the heart muscle of a doe. The sarcocyst (microcyst) infection in a particular animal species could be established through investigating the muscles of several organs. All data obtained are given in two tables.

Animal Population Groups↗
PubMed1976

[Extent and intensity of invasion and localization of macroscopically visible sarcocysts in the carcasses of slaughtered sheep].

Studied were with a naked eye a total of 8185 carcasses of adult sheep and weaned lambs slaughtered at the abattoirs of Bourgas and Yambol at the age of one year as well as 1783 heads, 1054 hearts, and 468 gullets of weaned lambs for the presence of macroscopically seen sarcocysts. The animals originated from more than 50 communities in the districts of Bourgas and Yambol. The parasite burden was investigated in 1291 sheep carcasses (without heads and viscera). The percent of animals infected with sarcocysts was found to be 95.75 (carcasses) and 63.10 (heads). N cysts were established in the heart muscle. 56.98 per cent of the sheep carcasses were infected with one to 10 cysts, 36.55 per cent - with 11 to 50 cysts, 4.86 per cent - with 51 to 100, 1.17 per cent - with 101 to 200 cysts, and 0.16 per cent - with more than 200 cysts. It was found that the greater part of the sheep carcasses presented sarcocysts both on the outer and on the inner (abdomen and thorax) surface. The parasite burden was more substantial inside the carcasses. Cysts were likewise observed throughout the carcasses, showing no strict localization. Weaned lambs slaughtered at the age of up to one year presented no sarcocysts seen with a naked eye. The necessity is stressed of more strict regulations of meat inspection, resp., hygiene evaluation of carcasses with view establishing sarcosporidia.

Animals↗
PubMed1975

[Sarcosporidia and sarcosporidiosis in agricultural animals. II. Sarcosporidiosis in cattle].

A total of 458 cows, oxen, and calves (up to the second year of age) were studied over the 1971-1973 period. The animals were slaughtered at the abattoir of the town of Bourgas, originating from 59 communities on the territory of Bourgas district where the field and feeding conditions varied. Samples were taken from the gullet, tongue, pharynx, diaphragm, cervical muscles, and heart, using the compression slide method to demonstrate the presence of microcysts. Sarcosporidia were found in 398 animals as follows: cows and oxen involved--99.11 per cent; calves--75.53 per cent. The average value for the whole group was 86.89 per cent. Lowest were the cases of parasitic infection in calves that were raised indoors, with lowest parasite burden in the animals involved. On the other hand, highest microcyst burden was found in calves that had been kept in mountainous grasslands. No differences were found in the extent of parasite infection between the animals of the two sexes. More severe was the infection in animals in the individual microregions (communities) and the mountainous region as a whole, and it was lowest in animals in the plain region of the district. Both the percentage of animals involved and the parasite burden showed year-to-year variations. Microcysts were observed in all investigated organs. The heart muscle was most frequently involved in all affected animals, showing also highest parasite burden. Lowest were the values concerning the skeletal musculature (cervical muscles). The data of the investigation are given in three tables.

Age Factors↗