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W Burrows

Publications and source records attributed to W Burrows.

At least 19 recordsLinked to original sources
PubMed1974

Accelerated cell death produced by a cholera cytotoxin on isolated epithelial cells from rabbit ileum.

Villus and crypt cells were removed from rabbit ileum by a modification of a method previously described. Villus cells were isolated by vibration of everted bowel segments in citrate buffer, and crypt cells were removed by the expansion of these segments with air and simultaneous vibration in citrate buffer. Several culture media were tested for the maintenance and/or culture of these cells. Two defined media, Eagle's minimum and medium 199, were unsatisfactory and led to rapid cell death. The presence of whole serum was beneficial and both cell types could be maintained for several hours when homologous rabbit serum was employed. Initially 70-80% of villus and crypt cells were viable in homologous serum, and the effect of cholera toxin on cell viability was studied by incubating the cells with peptone dialysate supernatant (PSUP) toxin from Vibrio cholerae for 4 h. PSUP toxin reduced the viability of both villus and crypt cells compared with control preparations, as measured by the uptake of trypan blue; cell death was accelerated with time. A purified, diarrhoea-inducing cholera toxin also reduced the viability of these cells and the results were comparable to those with PSUP toxin. The effect was usually immediate, and a significant reduction in viability occurred within 1 hour of the incubation of cells with toxin. The toxin was heat-labile (60 degrees C/30 min) and nondialysable, and its cytotoxic activity could be completely neutralized with cholera antitoxin. Dose-response studies indicated that as little as 0.0275 equivalent units of ligated ileal loop toxin were active in this system.

Animals↗
PubMed1969

Cholera toxins: immunogenicity of the rabbit ileal loop toxin and related antigens.

A method of assay of immunogenic potency of the cholera gut toxin is described; it is based on the relation of dose of antigen to neutralizing antibody titer produced in the rabbit under defined conditions and allows quantification of immunogenicity as immunogenic units per milligram of protein. Evidence, based on immunogenicity and rabbit ileal loop toxicity, is presented which indicates that the positively charged fraction of liquid-culture supernatant fluid eluted in deionized water from diethylaminoethyl Sephadex, or in electrolyte from carboxymethyl Sephadex, is a complex made up of a nonantigenic toxic moiety, a nontoxic protein component which elicits the formation of toxin-neutralizing antibody, and an inactive fraction. The complex may also be dissociated in high-salt concentrations with apparent recombination of the toxic moiety with a nondialyzable constituent of peptone to give a negatively charged complex. The immunogenic component is found in nontoxic supernatant fluids of cultures grown at pH 6.5 or in media deficient in peptone. It is also present in the nontoxic fraction eluted from diethylaminoethyl Sephadex in electrolyte or in deionized water from carboxymethyl Sephadex. When separated from the positively charged toxic moiety, the net charge of the antigen is reduced as shown by immunoelectrophoresis. On primary fractionation, the antigen may be associated with a minor antigenic component of the negatively charged complex containing a major antigen eliciting vibriocidal antibody formation, but antisera to the toxin antigen preparations, either in this form or freed of antigenic contamination by recycling, do not contain vibriocidal antibody. It is suggested that this antigen be designated the T (toxin) antigen, and the antigen producing vibriocidal antibody the V antigen. These two antigens would appear to represent the major antigenic specificities associated with the antitoxic and antibacterial elements of the immune response to infection.

Animals↗
PubMed1969

Immunity to cholera: relation of fraction II of type 2 cholera toxin to vibriocidal antibody.

The nontoxic protein component in supernatant fluids of young cultures of the cholera vibrio in peptone dialysate broth contains an antigen identical in specificity to vibrio lipopolysaccharide. This material was heterogeneous after elution from diethylaminoethyl A50 Sephadex, and it contained at least five additional minor antigens. Identity was demonstrated by immunodiffusion methods, by the induction of specific vibriocidal antibody formation, and by specific interference in the vibriocidal reaction. The minor antigens appeared to be unrelated to the vibriocidal reaction. The major antigen was more highly immunogenic than lipopolysaccharide, giving higher and longer-persisting antibody titers in the rabbit, but lipopolysaccharide was the more effective interfering antigen per unit weight in the vibriocidal reaction. The nontoxicity and high immunogenic potency of the protein antigen suggest that it may be useful as an immunizing agent for the production of the antibacterial component of an effective immunity.

Animals↗
PubMed1968

Cholera toxins: purification and preliminary characterization of ileal loop reactive type 2 toxin.

Details for the preparation and partial purification of culture supernatant fluids of Vibrio cholerae (V. comma) 569B which retain rabbit ileal loop fluid-accumulating activity are presented. These preparations were fractionated on Sephadex G-200 and on diethylaminoethyl-Sephadex. On the latter, two fractions were obtained by elution with a linear sodium chloride gradient. The fraction designated "fraction I" retains the toxic activity as demonstrated in the rabbit ileal loop model. Chemical and immunological properties of this active fraction are described.

Amino Acids↗