PubMed Health⌕ Search

Biomedical subjects

D E Stewart-Tull

Publications and source records attributed to D E Stewart-Tull.

At least 19 recordsLinked to original sources
PubMed1992

Adjuvanted oral vaccines should not induce allergic responses to dietary antigens.

Oral vaccines may contain adjuvants which might elicit allergies against dietary proteins. Four antigens were used to measure such an effect--ovalbumin, soya bean protein, lactalbumin and gluten. Neither guinea pigs nor mice showed IgE responses after oral administration of adjuvanted vaccines containing lactalbumin and gluten. No IgE responses were detected in mice with any of these antigens after oral immunization, but, in the guinea pig, nine out of 18 animals reacted to either ovalbumin or soya bean protein and none reacted to lactalbumin and gluten. It is concluded that the risk of allergy induction against normal dietary proteins is low but such tests should be applied to potential adjuvanted oral vaccines to measure any possible contraindication, especially with atopic individuals.

Administration, Oral↗
PubMed1989

Optimal conditions for the toxoiding of pertussis toxin with 1-ethyl-3(3-dimethylaminopropyl) carbodiimide.HCl.

The optimal conditions for toxoiding a pertussis toxin (PT) preparation with 1-ethyl-3(3-dimethylaminopropyl) carbodiimide.HCl (EDAC) were determined. The prime factor affecting the toxoiding of PT was the EDAC to protein ratio. A ratio of 40-80: 1 EDAC to protein by weight was optimal for abolishing the acute toxicity, histamine-sensitising and leucocytosis-promoting activities associated with PT, whilst maintaining the antigenicity of the vaccine antigens. An EDAC-toxoid also manifested no late histamine-sensitising activity. Duration of exposure to EDAC, temperature and pH value of the reaction were found not to be critical for toxoiding. The data indicated that the use of EDAC for toxoiding PT in a B. pertussis extract is a simple and reproducible procedure and should be considered as a method for the production of acellular pertussis vaccines.

Animals↗
PubMed1988

Studies on the Vibrio cholerae mucinase complex. III. Neutralisation of the neuraminidase activity by specific anti-neuraminidase IgG.

A partially-purified neuraminidase from the mucinase complex of Vibrio cholerae was used to prepare a specific anti-neuraminidase antiserum in rabbits. When the neutralising potency of this serum against V. cholerae neuraminidase was assessed in conventional tests, the enzymic activity, as measured by thiobarbituric acid, methoxyphenol-neuraminate and goblet-cell assays, apparently increased. These results are attributable to the presence of a sialylated glycoprotein substrate and small amounts of sialidase in the crude antiserum. However, a twice-purified DEAE-IgG fraction of the antiserum neutralised the enzymic activity of the V. cholerae neuraminidase.

Alcian Blue↗
PubMed1988

A sensitive chemiluminescence assay for pertussis toxin and for evaluation of cell-free pertussis toxoids.

Pertussis toxin (PT) inhibited luminol-enhanced chemiluminescence induced in rabbit peritoneal neutrophils by N'-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) at doses as low as 0.8 ng.ml-1, even in the presence of a 10-fold higher concentration of filamentous haemagglutinin (FHA). A cell-free extract of Bordetella pertussis, containing predominantly PT and FHA, suppressed the neutrophil response to fMLP. After toxoiding with carbodiimide, the inhibitory activity of the extract was abolished and an enhancement of neutrophil chemiluminescence was observed due to FHA activity. Abrogation of the chemiluminescent response of neutrophils to fMLP is proposed as a sensitive, in vitro assay for pT, and may be useful for monitoring the residual toxin activity in pertussis toxoids and for determining the anti-toxic effects of anti-PT antibodies.

Animals↗
PubMed1987

Acellular pertussis vaccine prepared by a simple extraction and toxoiding procedure.

An extract containing predominantly pertussis toxin (PT) and filamentous haemagglutinin (FHa) was obtained from culture supernates of Bordetella pertussis by a single-step procedure using dye-ligand chromatography. The pathophysiological activities associated with the pertussis toxin component were removed by treatment with a water-soluble carbodiimide. The product was stable at 4 degrees C, was non-toxic for mice, induced high levels of IgG antibodies to both PT and FHa in vaccinated animals as judged by ELISA, and protected mice from intracerebral and intranasal challenge with B. pertussis.

Animals↗
PubMed1987

Studies on the Vibrio cholerae mucinase complex. II. Specific neuraminidase activity measured histochemically in a goblet cell assay.

The activity of neuraminidase prepared from the mucinase complex of Vibrio cholerae was measured by a new, semi-quantitative goblet-cell assay. The counts of normal, alcianophilic, sialomucin-containing goblet cells (purple-stained) and neutral mucosubstance-containing goblet cells (magenta-stained) in serial sections of ileum were compared before and after neuraminidase treatment. The procedure provides a more natural assessment of the action of V. cholerae neuraminidase on the viscous intestinal mucus.

Alcian Blue↗
PubMed1987

Corneal test as a reliable method for detection of the delayed-type hypersensitivity reaction in mice.

Antigen solution could be injected into the cornea of sensitized mice using a fine needle and a stereoscopic dissecting microscope. The resulting corneal reaction was shown to be a reliable method in the detection and estimation of delayed-type hypersensitivity in mice that had been immunized with a water-in-oil emulsion containing an ovalbumin and a cell wall adjuvant. Unlike the delayed skin reaction in the ear lobe, this corneal reaction was not affected by a coexisting Arthus reaction.

Animals↗
PubMed1985

Immunopotentiating conjugates.

Current interest in the development of sub-cellular vaccines and in cancer immunotherapy has rekindled interest in immunopotentiating agents. In addition, peptide sequences of protective antigens are being synthesized or genetically engineered and it is likely that these peptides will have a small relative molecular mass and be non-immunogenic by themselves. A variety of experimental studies have shown that such protective antigens could be included in conjugated vaccines with carrier protein and/or immunopotentiator. The insertion of peptides with hydrophobic sequences into artificial lipid bilayers (liposomes) offers another mode of presentation of antigen to the immune system.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1984

Leprosy--in pursuit of a vaccine.

Clinical leprosy is characterized by varying manifestations between tuberculoid and lepromatous leprosy. In the former state the patient is able to elicit a cell-mediated immune response whereas in the latter, there is usually a humoral response. An understanding of this immunological balance is crucial in the search for a vaccine which will control the disease. The development of a possible anti-Mycobacterium leprae vaccine has been advanced by the isolation of organisms from the infected tissues of the nine-banded armadillo, Dasypus novemcinctus; 125 000 doses can be prepared from one animal. In addition, recent studies on the biochemical activities of these organisms may provide the knowledge required to allow cultivation on a laboratory medium. Eventually it may be possible to produce a combined leprosy:tuberculosis vaccine for use in those parts of the world where both diseases are prevalent.

Bacterial Vaccines↗
PubMed1984

Factors affecting the lethality of Campylobacter fetus subspecies jejuni in mice.

Intraperitoneal injection of Campylobacter fetus ss. jejuni into HAM/1CR mice was lethal, but viable counts of bacteria from whole body homogenates, organs and blood indicated that death was not due to sustained bacterial multiplication. Heat-killed organisms (5 X 10(9) cfu) injected into 7-day-old mice caused death within 24 h and this was shown to be due to endotoxin. Both ferric iron and heterologous lipopolysaccharide enhanced virulence; the LD50 was lowered from 1.8 X 10(9) cfu to 2.7 X 10(7) cfu when both were used. Three-day-old or adult animals survived challenge with Campylobacter fetus without clinical symptoms when challenged orally or by intravenous or intraperitoneal routes.

Aging↗
PubMed1984

Cellular responsiveness in vitro: the effect of mycobacterial glycopeptides, glycolipids and peptidoglycolipids on the in vitro growth of haemopoietic colony-forming cells.

Incorporation of glycopeptide, glycolipid and peptidoglycolipid preparations from the culture fluid or organisms of a variety of mycobacterial species in suboptimally stimulated cultures of normal mouse bone marrow cells increased the responsiveness of colony-forming cells to colony-stimulating factor, as measured by enhanced colony formation. Possible mechanisms of action and the significance of enhanced colony growth in relation to the mode of action of mycobacterial adjuvants are discussed.

Animals↗
PubMed1981

The affinity of bacterial polysaccharide-containing fractions for mammalian cell membranes and its relationship to immunopotentiating activity.

The natural affinity of various bacterial glycopeptides and lipopolysaccharides for mammalian cell membranes was estimated quantitatively by comparison with the adsorption of lipopolysaccharide from Escherichia coli NCTC 8623 to erythrocytes, thymocytes, bone marrow cells, spleen cells, peritoneal lymphocytes and macrophages. Immunopotentiating activity was estimated by measuring the ability of the bacterial fractions to stimulate a humoral response to ovalbumin in HAM/1CR mice. When the affinity for mammalian cell membranes was compared with the stimulation of the antibody response, it was found that a negative correlation for peritoneal macrophages (rs = -0.94, P less than 0.0005) and a positive correlation for peritoneal lymphocytes (rs = +0.97, P less than 0.0005) and spleen cells (rs = +0.76, P less than 0.005) existed.

Adjuvants, Immunologic↗
PubMed1978

The binding of lipopolysaccharide from Escherichia coli to mammalian cell membranes and its effect on liposomes.

The kinetics of the absorption of 32P- or 14C-labelled lipopolysaccharide from Escherichia coli NCTC 8623, serotype 0 125, chemotype XII, to erythrocytes, leukocytes, peritoneal macrophages and peritoneal lymphocytes was examined. Under variable conditions maximal levels of binding were found due to saturation of receptor sites on the cell membrane or steric hindrance by bound lipopolysaccharide. During adsorption slight leakage of haemoglobin was found but complete lysis of erythrocytes was ruled out after noting the effect of lipopolysaccharide on artificial lipid bilayers. The affinit of lipopolysaccharide to cell membranes revealed a consistent pattern of cyclic fluctuation between adsorption and desorption. A model was proposed to explain this cyclic fluctuation in binding based on membrane reorganization. It was significant that the cycle of lipopolysaccharide adsorption-desorption proceeded to completion even if the process was interrupted. The indication was that, once triggered, membrane reorganization occurred independently without influence from the test environment.

Animals↗
PubMed1978

The binding of adjuvant-active mycobacterial peptidoglycolipids and glycopeptides to mammalian membranes and their effect on artificial lipid bilayers.

The nature of the binding of adjuvant-active amphiphilic mycobacterial peptidoglycolipids and glycopeptides to mammalian plasma membranes was investigated together with their effect on the stability of artificial lipid bilayers. The importance of these interactions between mycobacterial components and membranes is discussed in relation to immunopotentiation, mitogenicity and tuberculous infection.

Adjuvants, Immunologic↗