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Biomedical subjects

K J Turner

Publications and source records attributed to K J Turner.

At least 73 records · Page 4Linked to original sources
PubMed1988

Relationship between mite densities and the prevalence of asthma: comparative studies in two populations in the Eastern Highlands of Papua New Guinea.

The recent dramatic rise from 0.1 to 7.3% in the prevalence of adult asthma in the South Fore area of the Eastern Highlands of Papua New Guinea (PNG) has not been matched by a similar increase in asthma in the adjacent Asaro valley, where the prevalence remains extremely low at 0.3%. While the living conditions of these two populations appear comparable, the mean density of house dust mite (principally Dermatophagoides pteronyssinus) in blankets of residents in the Asaro valley was found to be significantly lower (283/g dust) than that of a corresponding random selection in the south Fore (1371/g dust). Since from 200 to 600 mites per g dust have been reported to constitute a risk factor for asthma, the data suggest that the relative risk for asthma in the Asaro valley population is low compared with that in the South Fore. In randomly selected sera, both IgE and IgG antibodies to D. pteronyssinus from the Asaro valley were comparable with those of a group of non-asthmatics from the South Fore (mean 4.39 vs 3.43 U/ml for IgE antibodies and 1832 vs 1815 U/ml for IgG antibodies for Asaro valley vs South Fore, respectively) but significantly lower (P less than 0.001) than corresponding data for subjects in the South Fore with asthma (108.6 U/ml and 3365 U/ml, respectively). This study emphasizes the interplay between genetic and environmental factors in determining the development of asthma, and highlights the importance of house dust mites in the pathogenesis of asthma in the Eastern Highlands of Papua New Guinea.

Adult↗
PubMed1988

Specificity of Toxocara ELISA in tropical populations.

The diagnosis of human infection by Toxocara canis relies heavily upon serological tests, the specificity of which can be inadequate in regions of endemic helminthiasis. When different population groups of tropical Venezuela were evaluated using ELISA based upon Toxocara excretory-secretory antigen (TcESA), solid-phase adsorption of the sera with extracts of a wide variety of non-homologous parasites revealed the existence of significant cross-reactivity. This was effectively and conveniently overcome when the test sera were incubated in the presence of the soluble parasite extracts in a competitive inhibition ELISA. The mean reduction of ELISA values caused by pre-adsorption of the sera tested was 32.2%, and that caused by competitive inhibition was 42.3%, the effects of these two procedures being strongly correlated (r = 0.83). The magnitude of the reduction was inversely proportional to the actual ELISA value (r = -0.55), and ranged from a mean of 68.0% in sera from apparently healthy individuals of medium-high socio-economic level, down to 28.1% in heavily parasitized Amazon indians. Ascaris showed the greatest degree of cross-reactivity in these tests, although under conditions of competitive inhibition even sera with high levels of antibody against this parasite could be negative in Toxocara ELISA. Western blotting revealed a major 81,400 D component that was shared between Ascaris and TcESA. Our results indicate that the competitive inhibition of cross-reactivity by soluble non-homologous parasite extracts provides a convenient and economical means of increasing the specificity of ELISA for the determination of the seroprevalence of toxocariasis in tropical populations.

Adsorption↗
PubMed1988

Ultrastructural localization of IgE in peripheral blood monocytes from atopics.

Monocyte-enriched preparations derived from peripheral blood leukocytes of atopics were probed via a cocktail comprising peroxidase-conjugated (Fab1)2 fragments of two monoclonal antibodies against human IgE. Reaction product indicative of intracellular IgE was identified by electron microscopy in both large and small vacuoles, and at high magnification exhibited a characteristic granular deposition pattern consistent with highly concentrated (perhaps insolublized) material. IgE-containing vacuoles were observed with comparable frequency to those containing IgG, despite the greater than 10,000-fold relative excess of the latter in serum suggesting highly selective uptake of IgE by the monocytes. These results are similar to those reported recently for IgA in human milk macrophages.

Antibodies, Monoclonal↗
PubMed1988

Standardization of rye-grass pollen (Lolium perenne) extract. An immunochemical and physicochemical assessment of six candidate international reference preparations.

Six candidate extracts of Lolium perenne (rye-grass) pollen have been studied in 6 laboratories using a variety of immunochemical and physicochemical techniques. Radioallergosorbent test inhibition, crossed immunoelectrophoresis, crossed radio-immunoelectrophoresis, sodium dodecyl sulphate-polyacrylamide gel electrophoresis combined with immunoblot, thin-layer isoelectric focusing and enzyme-linked immunosorbent assay inhibition were used to evaluate each of the coded extracts. The source materials were also studied for identity and possible contamination by light microscopy. On the basis of these data, the Rye-Grass Working Party recommended to the Steering Committee of the Allergen Standardization Subcommittee of the International Union of Immunological Societies that the extract coded C be chosen as the candidate international reference preparation.

Allergens↗
PubMed1987

Nematospiroides dubius and Nippostrongylus brasiliensis: delayed type hypersensitivity responses to ovalbumin in the infected mouse.

Mice (C57BL) infected with the intestinal nematode Nematospiroides dubius showed depressed delayed type hypersensitivity responses to ovalbumin administered subcutaneously in Freund's complete adjuvant. IgG and IgM responses to this inoculum were unaffected. It is unlikely that the depression arose from impairment of the ear test response because responses to an extract of the adult parasite were measurable and ear testing with lipopolysaccharide yielded normal responses in infected mice. Furthermore, mice immunized on the day of infection responded normally, whilst long term infected mice ear challenged with antigen pulsed macrophages gave depressed responses. The in vitro proliferative responses of cells from the spleens and from the lymph nodes draining the site of immunization were enhanced marginally by N. dubius infection. Furthermore, these cells induced normal or elevated adoptive delayed-type hypersensitivity and IgG responses in irradiated recipients. These findings suggest that N. dubius does not compromise the development of ovalbumin specific T cells involved in a delayed type hypersensitivity response. Evidence for the induction of suppressor cells by N. dubius is discussed, and the findings are compared with results obtained with Nippostrongylus brasiliensis, a parasite which is rejected rapidly from the mouse.

Animals↗
PubMed1987

An immunochemical investigation of the allergens from Ascaris suum perienteric fluid. Cross-reactivity, molecular weight distribution and correlation with phosphorylcholine-containing components.

An extract of Ascaris suum perienteric fluid was fractionated on Sephadex G-200 and the resulting high molecular weight (approx. 600,000 daltons) and low molecular weight (approx. 16,000 daltons) fractions examined for allergenicity using human sera. Radioallergosorbent (RAST) and RAST-inhibition assays showed that the high molecular weight fraction was 15- to 40-fold more potent than the low molecular weight fraction. Crossed radio-immunoelectrophoretic analysis showed that the high molecular weight fraction contained 10 allergens in contrast to the 6 comprising the low molecular weight fraction. Polyacrylamide gel electrophoretic studies in combination with RAST indicated that two high molecular weight glycoprotein-staining components may be major allergens. A. suum cross-reacted allergenically with Toxocara canis and various life cycle stages of Nippostrongylus brasiliensis but not with Strongyloides ratti or Schistosoma mattheei. The cross-reacting allergens were predominantly of high molecular weight and the molecular weight distribution pattern obtained for A. suum, T. canis and N. brasiliensis paralleled that obtained for the distribution of the carrier of the hapten phosphorylcholine (Pc). However, it was shown that the hapten per se was not allergenic. In contrast, analysis of the allergens from N. brasiliensis using sera from rats infected with the same parasite showed that the homologous allergens were predominantly of low molecular weight (approx. 20,000 daltons) and did not contain Pc.

Allergens↗
PubMed1987

Functional heterogeneity within the human peripheral blood B cell pool engaged in IgE synthesis.

Fractionation of human peripheral blood leukocytes (PBL) B cells by differential sedimentation on percoll gradients separates B cell subpopulations which vary markedly in rates of spontaneous IgE synthesis, in their response to identical populations of autologous T cells and in their response to soluble T cell factors. This B cell fractionation technique often reveals the presence of active IgE-secreting cells which are totally suppressed within unfractionated PBL B cell preparations and greatly improves the efficiency of detection of T cell-responsive, IgE-producing B cells in PBL of atopics.

Adult↗
PubMed1987

Seasonal variations in in vitro synthesis of rye pollen-specific IgE by human peripheral mononuclear cells. Functional heterogeneity within the IgE-B pool.

Peripheral blood mononuclear B cells from 6 rye pollen-allergic patients, with no consistent perennial symptoms, were isolated before (July), during (October) and after (February and May) the pollen season. The T-depleted cells were fractionated on a discontinuous percoll density gradient and the B cell fractions, together with unfractionated B cells, incubated in vitro for quantitation of spontaneous synthesis of rye pollen-specific IgE. Markedly higher levels of IgE were synthesised by the fractions, as opposed to unfractionated B cells. The low-density fraction (B5) contributed most towards synthesis in the pollen season and the denser B6 cells in the pre- and post-pollen season. All low-density B cell fractions (B1-3-B5) and some high-density fractions contained large but variable amounts of preformed specific IgE which was retained, even in the absence of de novo synthesis in vitro, during the post- and pre-pollen season. Since only a fraction of this preformed IgE escaped into culture supernatants the contribution of preformed IgE to in vitro IgE synthesis in general may require reappraisal.

Adult↗
PubMed1987

Physicochemical characterization of a major protein allergen, Der p I, from the house dust mite, Dermatophagoides pteronyssinus. Amino acid analysis and circular dichroism studies.

A major house dust mite allergen, Der p I, was isolated from spent growth medium and physicochemically characterized. These studies show that the allergen is monomeric, contains approximately 216 residues and 4 intra-chain disulphide bonds. The N-terminal amino acid is threonine. Circular dichroism studies show that the allergen contains 10% alpha-helical, 50% beta-pleated sheet and 40% random structures.

Allergens↗
PubMed1987

In vitro synthesis of IgE by human peripheral blood leucocytes: V. Functional heterogeneity within the IgE-B-cell pool.

Fractionation of human peripheral blood leucocytes (PBL) B cells by differential sedimentation on a discontinuous Percoll gradient separates B cell subpopulations which vary markedly in rates of spontaneous IgE synthesis, often revealing the presence of active IgE secreting cells which are totally suppressed within unfractionated PBL B cell preparations. The production in vitro of IgE by separated B cell populations from the same individual may respond disparately to an identical population of autologous T cells and to pokeweed mitogen. Kinetic studies revealed major differences in both the rates of release of cell-associated IgE between these B cell populations, and their rates of de novo IgE synthesis. From a methodological viewpoint, the use of this B cell fractionation technique is demonstrated to improve greatly the efficiency of detection of T cell-responsive IgE producing B cells in peripheral blood from atopics, and from a mechanistic standpoint raises the possibility that B cell heterogeneity may modulate the functional expression of IgE-regulatory T cells signals.

Adult↗
PubMed1986

Studies on bronchial hyperreactivity, allergic responsiveness, and asthma in rural and urban children of the highlands of Papua New Guinea.

The prevalence of asthma and allergic responsiveness in rural and urban children of the highlands of Papua New Guinea was studied. Bronchial provocation studies with histamine demonstrated significant bronchial hyperreactivity in 0.5% (1 in 195) rural and 1.7% (1 in 59) urban children, rates which were significantly lower than those observed in corresponding adult populations (7%). Urban children demonstrated a higher incidence of skin test reactivity toward Dermatophagoides pteronyssinus, Aspergillus fumigatus, and dog dander than did the rural children. However, there were no significant differences between these populations with regard to total serum IgE levels, the degree of parasitism as judged by stool examination, or allergic responses to Ascaris suum, plantain, and coffee bean husk. A more detailed study demonstrated age- and sex-related differences in total IgE and mite-specific RAST scores in the rural but not the urban population. These data suggest an active suppression of the capacity of children to mount an IgE response to environmental allergens such as the mite manifesting itself as low asthma prevalence. The data also indicate that, although the underlying defect of bronchial hyperreactivity in asthma may be genetically inherited, it is not revealed until the lung has received an allergen-induced inflammatory insult.

Adolescent↗
PubMed1986

Immunological consequences of intestinal helminth infections. Cellular and anamnestic responses to ovalbumin.

Depressed IgG responses to ovalbumin administered with the inflammatory adjuvant, Al(OH)3, have previously been demonstrated in mice immunized 5 to 13 days after infection with Nematospiroides dubius, when the parasite is encysted in the intestinal mucosa or becoming established in the lumen. This report extends these findings to show that primary IgE and delayed-type hypersensitivity (DTH) responses, the generation of antigen-primed cells detectable in syngeneic irradiated recipients or in vitro and the recall of immunological memory are correspondingly impaired. Co-transfer experiments using irradiated recipients demonstrated weak suppressor activity in spleen cells from infected mice which was not attributable to T cells. The results suggest that N. dubius administered before immunization can impair the development of many classes of antigen-primed lymphocytes. The implications of this finding with respect to parasite survival are discussed.

Aluminum Hydroxide↗
PubMed1986

Specific Polysome Immunoadsorption to Purify an Ammonium-Inducible Glutamate Dehydrogenase mRNA from Chlorella sorokiniana and Synthesis of Full Length Double-Stranded cDNA from the Purified mRNA.

A specific polysome immunoadsorption procedure, employing soluble rabbit anti-NADP-GDH IgG and sheep anti-rabbit IgG covalently-linked to an insoluble cellulose matrix, was used to immunoselect polysomes translating mRNA for a chloroplastic ammonium-inducible NADP-GDH in fully induced cells of Chlorella sorokiniana. The immunoselected polysomes were dissociated, and the NADP-GDH mRNA was recovered by oligo (dT)cellulose chromatography. The translatable NADP-GDH mRNA was estimated to be 0.07 and 90% of the total polysomal poly(A)(+)RNA before and after immunoselection of the polysomes, respectively. The immunoadsorption procedure resulted in an 83% recovery and 1,291-fold purification of translatable NADP-GDH mRNA. In vitro translation of the immunoselected poly(A)(+)RNA yielded a single radioactive protein (on sodium dodecyl sufate polyacrylamide gels) with a molecular weight of 58,500, i.e. size of the putative precursor-protein of the NADP-GDH subunit in the holoenzyme in fully induced cells. The purified NADP-GDH mRNA was used for synthesis of a high proportion of nearly full-length single-stranded cDNA and double-stranded cDNA molecules.

Journal Article↗
PubMed1986

IgE antibody against surface antigens of Leishmania promastigotes in American cutaneous leishmaniasis.

As IgE-mediated immune mechanisms participate in the host defence against some types of parasites, we evaluated sera from American cutaneous leishmaniasis (ACL) patients for the presence of this antibody against Leishmania. Using monoclonal antibodies against human IgE and an immunoperoxidase staining technique, 48% of the patients sera tested were found to contain IgE antibody that bound strongly to Leishmania promastigotes. A much lower proportion of sera from non-symptomatic subjects from either endemic or non-endemic areas of the disease contained significant levels of anti-Leishmania IgE antibody (6.5% and 0% respectively). The results indicated that the IgE antibody bound predominantly to surface components of the promastigotes, and reactivity against the intracellular amastigote form of the parasite was rarely detected. Somewhat unexpectedly, in a small proportion of the sera, the IgE antibody showed apparent specificity for L. mexicana or L. braziliensis. This study demonstrates that ACL patients can develop anti-Leishmania IgE antibody responses, that seem to be directed preferentially against surface antigens of promastigotes, and that can be strain specific. This raises the question as to the possible contribution of this antibody to the immune defence mechanisms against the parasite.

Animals↗