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Biomedical subjects

O Olsvik

Publications and source records attributed to O Olsvik.

84 records · Page 5Linked to original sources
PubMed1982

Enterotoxin production in milk at 22 and 4 degrees C by Escherichia coli and Yersinia enterocolitica.

Enterotoxigenic Escherichia coli (five strains) and Yersinia enterocolitica (five strains) were cultivated in sterile milk at 22 and 4 degrees C. The bacteria grew well at both temperatures. Three strains of E. coli produced heat-labile enterotoxin in the milk at 22 degrees C as demonstrated by enzyme-linked immunosorbent assay. Heat-stable enterotoxins were not detected in milk by the infant mouse test.

Animals↗
PubMed1982

Demonstration of extracellular chymotrypsin-like activity from various Legionella species.

Concentrated extracellular supernatants from Legionella pneumophila, L. bozemanii, L. dumoffi, L. gormanii, but not L. micdadei, exhibited a strong chymotrypsin-like activity upon synthetic chromogenic tri- and tetrapeptides. Bacterial cell sonic extracts showed low protease activities, different from those of the extracellular concentrates. Extracellular concentrates were also tested in the API ZYM system, where weak protease activity only was recorded. Protease inhibitors decreased the activity of the extracellular Legionella proteases upon the chromogenic peptides.

Chymotrypsin↗
PubMed1981

The CAMP test performed by using Staphylococcus aureus sphingomyelinase (beta-haemolysin) and Clostridium perfringens lecithinase.

The CAMP test was performed by employing Staphylococcus aureus beta-haemolysin (sphingomyelinase) and Clostridium perfringens alpha-toxin (lecithinase) for identification of group B streptococci on blood agar, using blood from different origin. Partial purification of Cl perfringens alpha-toxin was carried out by means of sheep erythrocytes. With the toxin preparations described positive CAMP reaction was obtained only on sheep blood agar. False positives with regard to group A streptococci could not be avoided by either of the methods.

Animals↗
PubMed1981

Hyaluronidase production, lactose and salicin fermentation and phage-typability in bovine group B Streptococci.

Hyaluronidase, also called the spreading factor, may be an important pathogenic factor for the streptococci. Production of hyaluronidase is found in 75% of human clinical isolates of group B streptococci, and we have in our investigation found the same frequency (74%) in 195 bovine isolates. Of the same 195 isolates 17% turned out to be lactose negative, a characteristic usually regarded as being typical of group B streptococci of human origin. These same strains were also mostly hyaluronidase positive. The parameters investigated: hyaluronidase production, lactose and salicin fermentation and phage-typability, can be useful in tracing the origin of the group B. However, bovine and human streptococcal populations do not seem to be completely distinguishable because overlapping exists between the characteristics.

Animals↗
PubMed1981

A sandwich ELISA method for detection of Staphylococcus aureus enterotoxins.

Staphylococcus aureus enterotoxins A, B, and C, were detected by means of a four-layer sandwich ELISA method. With toxin produced in broth supernatants, this ELISA method had a detection limit of 0.5 ng enterotoxin per ml. Conjoint with enterotoxin, S. aureus most often produces protein A. The protein A will interfere and produce false positive reactions in a sandwich ELISA, by binding nonspecifically the IgG in different layers, simulating the immunospecific toxin binding. With rabbit IgG coupled to Sepharose CL-4B gel, 99% of protein A could be removed from solutions, bringing the level under the interfering limit in the ELISA.

Adsorption↗
PubMed1981

Enterotoxin production by Staphylococcus aureus related to the origin of the strains.

The production of enterotoxins by strains of Staphylococcus aureus of human and animal origin seems to be common. 104 out of 170 strains (61%) produced one or more of the A, B, and C enterotoxins. Strains from cow and milk often produced enterotoxin C, and enterotoxin A producing strains were mainly isolated from dogs. Human food poisoning seemed in our material to be induced by enterotoxin A producing strains.

Animals↗
PubMed1980

[Production and purification of thermolabile enterotoxin of Escherichia coli (author's transl)].

Heat labile enterotoxin (LT toxin) of Escherichia coli could be produced optimally and quantitatively in a trypticase soy broth with 0.2% yeast extract after 12 hours. Treatment of the cells with polymyxin B increased the yield of LT toxin. After concentration by ammonium sulphate precipitation, the LT toxin fraction was separated successfully from other proteins by Ultrogel AcA-34 gel exclusion chromatography. A 0.15 mol/l Tris-HCl buffer with gradually increasing pH was used as eluent. Purity was determined by gel electrophoresis. The presence of LT toxin in one isolated fraction ws demonstrated in vitro by assaying activity in the intestines of rats (by collection of liquid and quantification of cAMP in intestinal fluid). The reproducibility of the LT fraction was ascertained by a specific radioimmunoassay (RIA) and by an enzyme-linked immunosorbent assay (ELISA). The LT fraction had a molecular weight of 72,000 dalton. Two subunits of the toxin with molecular weights of 30,000 and 40,000 dalton respectively were found.

Bacterial Proteins↗