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At least 19 recordsLinked to original sources
PubMed1979

Conformational investigation on the bacterial polysaccharide xanthan.

The conformation of xanthan has been investigated as a function of temperature, ionic strength, and polymer concentration. A reversible transition induced by temperature is demonstrated; the melting temperature (TM) is directly correlated to the total ionic-strength and is independent of the polymer concentration. Measurements of circular dichroism show that the polysaccharide exists in a combination of only two characteristic conformations (random and ordered), regardless of the temperature and the concentrations of salt and polymer. Hydrodynamic measurements show that the hydrodynamic volume of both conformations is almost constant over the range of temperature investigated. The mechanism proposed by Morris for melting is confirmed, and a multichain process is excluded. The birefringence stability of the concentrated solutions is discussed.

Carbohydrate Conformation↗
PubMedDate not supplied

[Specific blast transformation of rabbit spleen cells induced by a bacterial polysaccharide and inhibitory effect of peripheral blood lymphocytes (author's transl)].

Following immunization with bacteria (i.e. Salmonella johannesburg), rabbit spleen lymphocytes developed a specific blast response when the lymphocytes were stimulated with polysaccharide, the haptenic moiety of lipopolysaccharide. A clear cut dissociation was noted in the blast response induced by polysaccharide compared with those induced by lipopolysaccharide and lipid A. There was no correlation between the magnitude of the cellular responses and that of the antibody response. Moreover, there was less specificity at the cellular level than at the level of antibody secreted by cells. A decrease of 3H-thymidine incorporation was often observed after immunization, at the level of peripheral blood lymphocytes. An inhibitory effect of these cells was shown on the blast response of spleen lymphocytes with polysaccharide. A high blast response to Salmonella polysaccharide which could be observed in some non-immunized rabbits might be related to a natural sensitization of animals with the same or related unknown antigens which could not be recognized by anti-S. johannesburg antibodies.

Animals↗
PubMed1977

[Effect of bacterial polysaccharide on the quantity of rosette-forming cells in mice with decreased immunologic reactivity].

The influence of bacterial polysaccharide on the amount of the rosette-forming cells (RFC) in mice with decreased immunological reactivity (irradiation in a dose of 400 rad, gamma-rays, administration of cyclophosphamide in a dose of 200 mg/kg) was studied. Bacterial polysaccharide increased the amount of RFC in the intact, immunized and irradiated animals. However, polysaccharide produced no stimulating action on the RFC formation in mice treated with cyclophosphamide this confirming different nature of depression of the immunological reactivity under the effect of irradiation and cyclophosphamide.

Animals↗
PubMed1979

[Effect of bacterial polysaccharide on the primary and secondary immunologic response following immunization with sheep erythrocytes].

The effect of typhoid bacterial polysaccharide on the primary and secondary immune response to SRBS was studied. The polysaccharide was shown to have both stimulating and depressive effect on the population of antibody-producing cells. This effect depended on the time and the number of polysaccharide injections. Thus, a single polysaccharide injection made on the day preceding immunization resulted in the maximum stimulation in the system of IgM- and IgG-producing cells, while the maximum depression of these cells could be observed after 2 polysaccharide injections: on the day preceding immunization and on the day of immunization. In the secondary immune response considerable stimulation of the populations of antibody-producing cells was observed after polysaccharide injections made on days 2 and 3 after reimmunization.

Animals↗
PubMed1979

Effect of bacterial polysaccharides on the growth of Gaeumannomyces graminis var. tritici and wheat roots.

Agrobacterium sp. and related species which in the soil and in the rhizosphere of wheat accompany the fungus Gaemannomyces graminis var. tritici and cause take-all of the wheat roots produced polysaccharides in pure cultures (glucans, mannoglucans and galactomannoglucans). These polysaccharides were utilized better by the mycelium of G. graminis than glucose and polysaccharides of plant origin that occurred on the surface of wheat roots (the so-called mucigel). At lower concentrations these bacterial polysaccharides stimulated growth of wheat roots, higher concentrations (more than 0.1%) were inhibitory. Bacteria inoculated on the surface of wheat first inhibited and then stimulated the development of the plants and their growth. Changes in the growth rate of wheat, the rhizosphere of which was colonized by bacteria simultaneously with the fungus G. graminis and also some changes in the course of the disease of wheat roots caused by the fungus can be explained by the inhibitory or stimulatory effect of polysaccharides of accompanying bacteria.

Ascomycota↗
PubMed1979

Bacterial polysaccharide synthesis: an experiment for the dental biochemistry laboratory.

A simple experiment is described for demonstrating the formation of a high molecular-weight polysaccharide from sucrose by a bacterial enzyme. The polysaccharide confers high viscosity on solutions. Dental students are encouraged to consider this as a component of the system leading to the formation of dental plaque and the initiation of carious lesions.

Biochemistry↗
PubMed1979

Antigenic bacterial polysaccharide in rheumatoid synovial effusions.

Phenol-water extracted rheumatoid synovial fluids and synovial fluid leukocytes contain an antigen immunologically identical to the Proprionibacterium group bacteria. The antigen was identified by counter-immunoelectrophoresis in 70% of rheumatoid synovial fluid leukocyte pellets and in 60% of rheumatoid synovial fluids. It was also present in 6% of nonrheumatoid fluids and in 22% of nonrheumatoid inflammatory fluid leukocytes. Antigen was not detectable in synovial samples before extraction. Synovial and bacterial antigens were further purified by proteolytic digestion and Sepharose 4B column chromatography. Biochemical and enzymatic studies of bacterial and synovial antigens were similar and consistent with a high molecular weight polysaccharide. Serum antibody to bacterial and synovial antigens was significantly less frequent in rheumatoid sera than in normal controls. The significance of demonstrating a bacterial polysaccharide primarily in rheumatoid synovial effusions is discussed.

Antibodies, Bacterial↗
PubMed1979

Bacterial polysaccharide which binds Rhizobium trifolii to clover root hairs.

Immunofluorescence, quantitative immunoprecipitation, and inhibition of bacterial agglutination and passive hemagglutination indicate that cross-reactive antigenic determinants are present on the surface of Rhizobium trifolii and clover roots. These determinants are immunochemically unique to this Rhizobium-legume cross-inoculation group. The multivalent lectin trifoliin and antibody to the clover root antigenic determinants bind competitively to two acidic heteropolysaccharides isolated from capsular material of R. Trifolii 0403. The major polysaccharide is an antigen which lacks heptose, 2-keto-3-deoxyoctulosonic acid, and endotoxic lipid A. The minor polysaccharide in the capsular material of R. Trifolii 0403 contains the same antigen in addition to heptose, 2-keto-3-deoxyoctonate, and lipid A. The acidic polysaccharides of two strains of R. trifolii share the clover r-ot cross-reactive antigenic determinant despite other differences in their carbohydrate composition. Studies with monovalent antigen-binding fragments of anti-clover root antibody and Azotobacter vinelandii hybrid transformants carrying the unique antigenic determinant suggest that these polysaccharides bind R. trifolii to the clover root hair tips which contain trifoliin.

Azotobacter↗
PubMed1978

Degradation of polysaccharides by intestinal bacterial enzymes.

Polysaccharides with structures resembling components of dietary fiber were fermented by a number of species of anaerobic bacteria from the human colon. Some strains also fermented glycoprotein mucins. The strains that fermented the widest range of polysaccharide substrates were in the two genera Bacteroides and Bifidobacterium. Polysaccharide degrading enzymes from several Bacteroides species have been studied, and in most cases the enzyme activities were cell bound rather than extracellular. In all cases, the polysaccharide degrading enzymes were inducible rather than constitutive. Thus the metabolic activity of the flora could be altered considerably by the amount and type of fiber in the diet, even though the composition of the flora itself remained unchanged. The products of enzyme action included monosaccharides and oligosaccharides of varying chain lengths.

Bacteroides↗
PubMed1978

[Effect of gentamycin, decamethoxin and prodigiozan on the course and outcome of experimental pyocyanic infection in white mice].

The therapeutic and prophylactic effectiveness of gentamicin, decamethoxin and prodigiozan was determined on albino mice infected with two-fold lethal doses of the antibiotic-resistant strain of Ps. aeruginosa. Correlation between the effectiveness of the drug and the dose and time of its administration was found. Pronounced prophylactic and therapeutic effect of gentamicin in combination with decamethoxin was noted. Prodigiozan, a bacterial polysaccharide had no significant effect on the experimental pyocyanic infection of albino mice.

Animals↗