PubMed Health⌕ Search

Biomedical subjects

B J Veltri

Publications and source records attributed to B J Veltri.

10 recordsLinked to original sources
PubMed1978

Factors affecting production of catalase by Bacteroides.

Several variables affected the production of catalase by members of the "Bacteroides fragilis group" of anaerobic bacteria. Both media yielded higher catalase levels than the respective agar media. Addition of hemin to media after autoclave sterilization, rather than before, significantly increased production of catalase. Both of these variables could be related to the available hemin concentration present in the medium being tested. Significantly higher amounts of hemin were required for catalase production than were required for growth. For catalase production by B. fragilis ATCC 25285, 1 microgram of hemin per ml was required. Of the various media tested, the use of chopped meat broth resulted in the highest levels of catalase production (up to 50 to 60 U of catalase per mg of protein). Of the various species and DNA homology groups tested, strains of B. fragilis and Bacteroides distasonis were catalase positive. Strains of Bacteroides thetaiotaomicron, Bacteroides ovatus, and Bacteroides eggerthi possessed variable catalase activity. Bacteroides vulgatus, Bacteroides uniformis, and DNA homology groups "3452A" and "subsp. a" were catalase negative. A catalase well test, in which equal volumes of 3% H2O2 and chopped meat culture are mixed, is described and recommended for routine catalase tests.

Anaerobiosis↗
PubMed1977

Fat of Coxiella burnetti in macrophages from immune guinea pigs.

The interaction between Coxiella burnetii and peritoneal macrophages obtained from immune guinea pigs was studied by transmission electron microscopy. Phagocytosis and subsequent fate of ingested phase I and II rickettsiae were compared. Phase I rickettsiae were more resistant to phagocytosis than were phase II organisms. Macrophages from phase I- and II-immunized animals were equally capable of phagocytizing rickettsiae. Phase I and II rickettsiae previously treated with normal serum multiplied and destroyed macrophages from guinea pigs that had been immunized with phase II rickettsiae. Phase II organisms were initially suppressed in macrophages from phase I-immunized animals, but eventually multiplied in these cells. In contrast, only phase I organisms were destroyed by macrophages from phase I-immunized animals. Treatment of rickettsiae with immune serum enhanced ingestion by macrophages and potentiated the destruction of organisms by both types of macrophages. The macrophage migration inhibition assay was performed on peritoneal exudate cells from immune animals. Migration of peritoneal macrophages from phase I-immunized guinea pigs was inhibited, whereas macrophages from phase II-immunized animals migrated when cells were cultured in the presence of killed, intact phase I or II C. burnetii.

Antibodies, Bacterial↗
PubMed1977

Carbohydrate repression of catalase synthesis in Bacteroides fragilis.

Catalase formation by Bacteroides fragilis was immediately stopped upon addition of glucose to a culture growing in peptone medium. Each of eight other carbohydrates fermented by the organism also repressed catalase formation. Without added carbohydrate, the strains produced relatively large amounts of catalase (25 to 50 U/mg of protein).

Bacteroides fragilis↗
PubMed1976

Electron microscopic study on the interaction between normal guinea pig peritoneal macrophages and Coxiella burnetii.

An electron microscopic study was conducted to explore the interaction between normal guinea pig peritoneal macrophages and phase I and II Coxeilla burnetii previously treated with either normal or immune serum. A comparison was made on the efficiency of phagocytosis and subsequent killing of rickettsiae by macrophages. Both phases of rickettsiae previously treated with normal serum multiplied within phagosomes after phagocytosis with resultant destruction of macrophages. In contrast, suspending rickettsiae in immune serum rendered them more susceptible to phagocytosis and potentiated their destruction within macrophages.

Animals↗
PubMed1972

Isolation and characterization of a native cell wall complex from Neisseria meningitidis.

A cell wall complex has been isolated by gentle methods from both the medium supernatant fluid and whole organisms of Neissieria meningitidis cultures. The two types of preparations have been shown to be essentially identical on the basis of chemical composition, electron microscopy, and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE). Four major components were identified in the complex: group-specific polysaccharide (4 to 10%), protein (45 to 65%), lipopolysaccharide (10 to 25%), and lipid (15 to 30%). The whole complex was found to be immunogenic in rabbits and to elicit production of antibody directed against the protein, the group-specific polysaccharide, and the lipopolysaccharide components. The isolated protein component was also found to be immunogenic in rabbits and to elicit production of serotype-specific antibody. The protein component was found to produce a band pattern in SDS-PAGE that is simple, reproducible, and strain dependent. The lipopolysaccharide component was found to have chemical and biological properties characteristic of bacterial endotoxin. We propose that this complex is representative of the outer trilaminar membrane of the meningococcal cell envelope in its native state.

Animals↗