Search PubMed⌕ Search

Biomedical subjects

W W Stewart

Publications and source records attributed to W W Stewart.

At least 19 recordsLinked to original sources
PubMed1991

Purification and characterization of human immunoglobulin IgA1 and IgA2 isotypes from serum.

A method is described for the simultaneous purification of IgA1 and IgA2 from human serum. Ammonium sulphate precipitation, gel filtration and ion-exchange chromatography on DEAE-Sephacel yielded a partially purified IgA preparation which was separated quantitatively into IgA1 and IgA2 by affinity chromatography on jacalin-Sepharose. The IgA1 which bound to the jacalin was eluted with 0.8 M D-galactose. The IgA1 preparation was apparently homogeneous by SDS-PAGE but contained a trace of C1-inhibitor and a second protein detected by immunoelectrophoresis. The IgA2 which did not bind to the jacalin was purified to apparent homogeneity by chromatography on columns of Protein G-Sepharose, Fastflow-S Sepharose and Superose 6. Typical yields were 95% and 58% for IgA1 and IgA2 respectively or 253 mg and 24 mg per 100 ml serum. The IgA1 and IgA2 were characterised by their reactivity with isotype specific monoclonal antibodies and sensitivity to bacterial proteinases. The IgA2 preparation apparently contained both allotypes, IgA2m(1) and IgA2m(2).

Chromatography, Gel↗
PubMed1991

The measurement of respiratory burst induced in polymorphonuclear neutrophils by IgA and IgG anti-gliadin antibodies isolated from coeliac serum.

The properties of IgA and IgG anti-gliadin antibodies from the serum of patients with coeliac disease have been compared. The antibodies were quantified by ELISA using microtitre plates coated with crude gliadin fractions. Their specificity was confirmed by immunoblotting. Heat-treated sera containing IgA antibodies stimulated chemiluminescence when added together with neutrophils to microtitre plates coated with crude gliadin. Sera containing only IgG antibodies were less efficient. When IgA and IgG were purified from a serum containing both classes of anti-gliadin antibodies, each of the preparations was able to stimulate neutrophil chemiluminescence in plates coated with gliadin. Although the yield of anti-gliadin antibody determined by ELISA was high, the ability of the purified immunoglobulins to stimulate neutrophil chemiluminescence was much less than that of the unfractionated serum. This loss of activity was shown to be due to the ability of each class of antibody to potentiate the activity of the other in the whole serum.

Adolescent↗
PubMed1990

The effect of antibody isotype on the activation of C3 and C4 by immune complexes formed in the presence of serum: correlation with the prevention of immune precipitation.

Radioimmunoassays for C3a and C4a have been used to measure the activation of complement during the formation of immune complexes in human serum by the interaction of DNP-BSA and each of 11 mouse anti-DNP monoclonal antibodies of varied isotype and affinity. Those containing IgG2 or IgM were potent activators of C4, whilst IgG1 containing complexes were less efficient. C3 activation in normal serum was similar for complexes containing IgG1, IgG2a, IgG2b or IgM. IgA complexes did not activate C3 or C4. All complexes except those containing IgA precipitated more slowly in serum than in buffer. IgG2 antibodies were potent activators despite being very slow to precipitate in buffer. In serum containing EGTA activation of C4 was abolished and precipitation of complexes occurred at the same rate as in buffer. Nevertheless, C3 activation still occurred by the alternative pathway for all IgG and IgM complexes. Antibodies of the same isotype did not necessarily activate complement to the same extent. The ranking of the ability to activate complement was the same as that observed when performed complexes containing the same antibodies were added to serum. The levels of C4a generated were similar under both conditions but for most antibodies more C3a was generated by preformed complexes.

Antibodies, Monoclonal↗
PubMed1990

The specificity of the human neutrophil IgA receptor (Fc alpha R) determined by measurement of chemiluminescence induced by serum or secretory IgA1 or IgA2.

Heat or chemically aggregated IgA or IgG stimulated degranulation of neutrophils with comparable efficiency. The same aggregates induced a neutrophil respiratory burst which could be measured by lucigenin-enhanced chemiluminescence. Serum IgA1 or IgA2 coated onto microtitre plates were both capable of inducing a respiratory burst in neutrophils, as was secretory IgA1 or secretory IgA2. All bursts were of similar size for a given concentration of IgA and were greater than the burst elicited by an equivalent concentration of IgG. For each subclass of IgA the respiratory bursts were dependent on their density on the opsonized surface. Since monomeric and dimeric forms present in secretory IgA preparations both elicit a respiratory burst in neutrophils, secretory component and J chain cannot block the receptor binding site on the Fc region. The potential of secretory IgA to act as an opsonin might have important consequences on mucosal surfaces where the availability of complement components is limited.

Antigens, CD↗
PubMed1989

Colloquium on scientific authorship: rights and responsibilities.

The Colloquium on Scientific Authorship was held at the National Institutes of Health (NIH) at a time of extraordinary scrutiny by the public of the ethics of scientists, as represented by intense interest of the press and the Congress of the United States. Indeed, several regulations dealing with scientific misconduct have been proposed during the last year in the Federal Register, and new legislation has been proposed in the Congress. As a result of these concerns, conferences have been organized by the Institute of Medicine, the American Association for the Advancement of Science/American Bar Association, the Council of Biology Editors, and other groups. The colloquium at NIH, which was held May 31, 1988, and sponsored by the Intramural Scientists, focused on publication practices, especially multiple authorship, as contributing to perceived difficulties. The participants suggested various changes in conventions related to authorship that might help prevent future problems.

Authorship↗
PubMed1988

Battle over error.

Explore the source record for details and available documents.

Biomedical Research↗
PubMed1988

The activation of C3 and C4 in human serum by immune complexes containing mouse monoclonal antibodies of different isotype and affinity: effects on solubilisation.

Radioimmunoassays for C3a and C4a have been used to measure the activation of complement in human serum by immune complexes containing DNP-BSA and each of 11 mouse anti-DNP monoclonal antibodies of varied isotype and affinity. When preformed complexes were added to serum, those containing IgG2 or IgM were potent activators of C4, whilst IgG1 complexes were less efficient. C3 activation in normal serum was similar for complexes containing IgG1, IgG2a, IgG2b or IgM. IgA complexes did not activate C3 or C4. Solubilisation of complexes was greatest for IgM and IgG2b and least for IgG2a and IgA. In serum containing Mg2+ EGTA C4 activation was abolished and the amount of C3 activation was lower for all IgG and IgM complexes. Antibodies of the same isotype did not necessarily activate complement to the same extent. Unexpectedly, three of the four IgMs activated C3 in EGTA. For IgMs, neither complement activation nor solubilisation correlated with affinity. For IgG1 antibodies, solubilisation was inversely proportional to affinity. C3 or C4 activation did not correlate with affinity.

Animals↗
PubMed1985

Parvovirus infection in pigs with necrotic and vesicle-like lesions.

Porcine parvovirus was isolated from many visceral organs and also from the brain, serum and skin specimens of swine with vesicular-like conditions. Severe lesions were reported to have occurred in the mouth, on the tongue and snout, on the coronary band and in the interdigital spaces. Also, parvoviral antigens were demonstrated, by immunofluorescence, in the outer layers of hair follicles in skin adjacent to coronary band lesions.

Animals↗
PubMed1985

Body composition in the cirrhotic patient with ascites: assessment of total exchangeable sodium and potassium with simultaneous serum electrolyte determination.

The precise mechanism of initiation and maintenance of the disturbed fluid and electrolyte balance in cirrhotic patients remains unclear. Measurement of total exchangeable potassium in 11 cirrhotic patients with ascites revealed marked depletion compared to 9 healthy volunteers. Total exchangeable potassium was 50.8 +/- 5.1 m moles/L TBW in the patient group compared to 75.2 +/- 3.4 m moles/L TBW in the control group (P less than 0.01, Mann-Whitney U Test). Total body exchangeable sodium measured 80.1 +/- 3.7 m mole/L TBW in the cirrhotic group, which is not significantly elevated compared to the value in healthy volunteers of 74.1 +/- 1.9 m mole/L TBW. Serum sodium was low in four of the cirrhotic patients (129-133 mEq/L); exchangeable sodium was low in only one of these four (53.4 m mole/L TBW). Serum potassium was low in two of the cirrhotics (2.6-2.9 mEq/L); total body potassium was depressed in both of these patients (43.5-50.1 m mole/L TBW). An additional three patients had a low total body potassium (29.6-48.9 m mole/L TBW) with normal serum levels (4.0-4.2 mEq/L). There was no correlation between serum and total exchangeable electrolyte levels (Pearson's regression, r = 0.16 and 0.23). This work confirms that serum levels are not reliable indicators of true body sodium and potassium stores. The decreased total exchangeable potassium appears to be related to loss of body cell mass rather than intracellular potassium depletion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

Bacteriuria with intestinal loop urinary diversion in children.

Bacteriuria and intestinal loop urinary diversion with open (refluxing) ureterointestinal anastomoses did not prevent normal renal and body growth in 44 children, who were followed for 55.2 months. A comparison of the long-term use of sulfamethoxazole and nitrofurantoin with no treatment showed no statistically significant changes in the stoma, loop residual, renal function, serum electrolytes and treatment or prevention of bacteriuria.

Adolescent↗
PubMed1977

Vesical endometriosis in a postmenopausal woman: a case report.

A case of endometriosis of the bladder extending into the bowel in a postmenopausal woman is reported. The origin of the tissue is mere conjecture. Five years before the onset of bleeding the patient had had an abdominal hysterectomy that may have seeded the adjacent vesical and small bowel tissue. It is hypothesized that the exogenous estrogen stimulated this tissue until it penetrated the bladder mucosa.

Aged↗