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Biomedical subjects

H Roberts

Publications and source records attributed to H Roberts.

At least 109 records · Page 6Linked to original sources
PubMed1985

Detection of Toxoplasma-specific IgM in cord blood sera by antibody-class capture enzyme-linked immunosorbent assay.

An antibody class capture (ACC) enzyme-linked immunosorbent assay (ELISA) utilizing an F(ab)2 conjugate was established and its specificity and reproducibility were determined. The test was further validated by comparing its results with those obtained by 2 overseas reference laboratories which used the indirect immunofluorescence antibody test (IIFT) for Toxoplasma-specific IgM. It was found that the F(ab)2ACC-ELISA was not affected by the presence of rheumatoid and antinuclear factor in serum, that it was reproducible (coefficients of variation less than 10.0%), and that it compared well with tests currently used overseas. ELISA was then used to test for the presence of Toxoplasma-specific IgM in cord blood sera. The results obtained to date are consistent with the hypothesis that the prevalence of congenital toxoplasmosis in the population of Adelaide is less than 1/2,000.

Antigens, Protozoan↗
PubMed1983

Hypocalcaemia--an unusual complication of successful chemotherapy for metastatic breast cancer.

Three cases of metastatic carcinoma of the breast are described in patients who presented with hypercalcaemia. They achieved an excellent regression of their disease with combination chemotherapy but despite this they clinically deteriorated. Investigation showed them to be hypocalcaemic due to temporary hypoparathyroidism. Correction of their serum calcium resulted in good symptomatic relief. The possible mechanisms for these changes are discussed and we feel that this unusual complication of successful chemotherapy should be remembered when patients fail to improve symptomatically despite a good disease response.

Antineoplastic Agents↗
PubMed1982

Transmembrane ferricyanide reduction by cells of the yeast Saccharomyces cerevisiae.

Both respiratory-competent and respiratory-deficient yeast cells reduce external ferricyanide. The reduction is stimulated by ethanol and inhibited by the alcohol dehydrogenase inhibitor, pyrazole. The reduction of ferricyanide is not inhibited by inhibitors of mitochondrial or microsomal ferricyanide reduction. Cells in exponential-phase growth show a much higher rate of ferricyanide reduction. The reduction of ferricyanide is accompanied by increased release of protons by the yeast cells. We propose that the ferricyanide reduction is carried out by a transmembrane NADH dehydrogenase.

Ferricyanides↗
PubMed1980

Biogenesis of mitochondria. oli2 Mutations affecting the coupling of oxidation to phosphorylation in Saccharomyces cerevisiae.

1. Two oligomycin-resistant strains of Saccharomyces cerevisiae have been isolated and shown to have mutations in the oli2 region of the mitochondrial DNA. On solid media containing a non-fermentable energy source, the mutant strains were able to grow only slowly at 28 degrees C and not at all at 18 degrees C or 36 degrees C. 2. When grown in a glucose-limited chemostat at 28 degrees C, the mutant strains were almost completely defective in oxidative metabolism. The mutant mitochondria contained significant levels of all respiratory enzymes, and an active, oligomycin-sensitive ATPase, but the ATP-32Pi exchange activity and P : O ratio were very low. 3. The mutations in these strains are genetically closely linked to mit mutations which have been shown to affect a 20 000-dalton ATPase subunit (Roberts, H., Choo, W.M., Murphy, M., Marzuki, S., Lukins, H.B. and Linnane, A.W. (1979) FEBS Lett. 108, 501-504). Since the mitochondrial ATPase in these mutant strains appears to be fully assembled, the defect in the coupling mechanism is probably a result of a small alteration in the structure of the 20 000-dalton ATPase subunit. 4. When the mutant strains were grown at 18 degrees C, the mitochondria had very low cytochrome oxidase activities, and reduced levels of cytochrome aa3. The largest subunit (Mr 40 000) of this enzyme was not synthesized.

Adenosine Triphosphatases↗
PubMed1980

Age-sex distribution of Toxoplasma antibody in the South Australian population.

Sera from 1071 patients in nine age categories were screened for Toxoplasma antibody by indirect immunofluorescence. Thirty per cent of the sera contained antibody at a titre greater than or equal to 1/16. The percentage of sera containing antibody rose from 3% in the 6 months--5 years age group to a maximum of about 40% in the 31--40 years age group. It remained constant thereafter. Eleven per cent of the 84 sera with Toxoplasma antibody titres greater than or equal to 1/128 had Toxoplasma IgM titres greater than or equal to 1/32. No significant difference was found in the possession of antibody between the sexes.

Adolescent↗
PubMed1979

Relationship between spontaneous abortion and presence of antibody to Toxoplasma gondii.

Five hundred and twenty-three pregnant women were screened to determine whether a relationship existed between spontaneous abortion, and the presence of antibody to Toxoplasma gondii. The percentage of women with this antibody and a past history of spontaneous miscarriage was not statistically different from the percentage of women without antibody and a past history of spontaneous abortion.

Abortion, Spontaneous↗
PubMed1979

Validity and uses of a screening questionnaire (GHQ) in the community.

The 30-item General Health Questionnaire (GHQ) has been validated against the criterion of a standardized psychiatric interview in the community. Used for screening, the GHQ misclassified 25 per cent of 105 respondents, being worse for men. Specificity and sensitivity were above .70. The alternative use of the GHQ as an estimator and as an indicator of morbidity in epidemiological surveys is described and discussed.

Epidemiologic Methods↗
PubMed1976

In vitro synthesis of steroids by a feminising adrenocortical carcinoma: effect of prolactin and other protein hormones.

The study describes the effects of ACTH, prolactin and other protein hormones on the synthesis and secretion of steroid hormones by tissue from a feminising adrenocortical carcinoma removed from a post-menopausal female. Steroid production by the tissue was determined by high resolution-mass fragmentography and by radioimmunoassay. Prolactin and ACTH stimulated the synthesis of estrogens by the tissue whereas GH, LH and ACTH were more effective than prolactin in stimulating androgen synthesis. The effect of protein hormones, other than ACTH, on adenylate cyclase activity of this tumour tissue indicated a lack of specificity of the membrane receptor sites.

Adenylyl Cyclases↗