Biomedical subjects

Richard H Steele

Publications and source records attributed to Richard H Steele.

6 recordsLinked to original sources

PubMed2006

Diagnostic accuracy of coeliac serological tests: a prospective study.

OBJECTIVE: The best way to test serologically for coeliac disease (CD) remains controversial, with endomysial (EMA), transglutaminase (TTG), and gliadin antibodies (AGA) being assessed in various combinations with no apparent standardization. The objective of this study was to evaluate whether TTG-IgA+/-TTG-IgG could be used as a replacement for endomysial antibodies as a reliable screen for CD in patients presenting to a major Australian tertiary referral hospital for assessment of symptoms consistent with CD. METHODS: Individuals referred for gastroscopic assessment of possible CD were prospectively evaluated by duodenal biopsy assessment. The following diagnostic methods were compared: dual-isotype transglutaminase (TTG-dual), combined-isotype transglutaminase (TTG-IgA+G), TTG-IgA, combined-isotype gliadin antibodies (AGA-IgA+G), AGA-IgA, and endomysial antibody assays. Clinical performance characteristics (sensitivity, specificity, area under the curve for receiver-operating characteristic analysis; AUROC) were assessed for all kits. RESULTS: The correlation between transglutaminase kits was generally good, with the best transglutaminase kit demonstrating high correlation (r=0.86) with endomysial antibodies. A comparison of different types of endomysial antibody assays displayed variable diagnostic performance (sensitivity 61.90-68.42%; specificity 80.00-98.57%; AUROC 0.71-0.83). Sensitivity (90.48-92.31%), specificity (80.77-82.89%) and AUROC values (0.92-0.94) for dual-isotype transglutaminase kits displayed narrow ranges. AGA assays were less sensitive (AGA-IgA: 42.31-46.15%; AGA-IgG: 61.54%) and less specific (AGA-IgA: 85.09-87.73%; AGA-IgG: 82.46-84.09%). Dual-isotype transglutaminase testing was diagnostically equivalent to transglutaminase-IgA (AUROC 0.92 versus 0.91, P=0.33). CONCLUSIONS: Our study suggests that transglutaminase screening (using the IgA+/-IgG isotype) is a sensitive and specific alternative to endomysial antibody testing in the serological assessment of CD. On the basis of our findings, AGA antibody testing no longer appears to be an essential part of the diagnostic strategy for adult CD.

Adolescent↗

PubMed2005

Hypersensitivity reactions to the polysorbate contained in recombinant erythropoietin and darbepoietin.

The following case reports are of two patients who have developed hypersensitivity reactions to the red cell growth hormones, darbepoietin and erythropoietin. The subsequent skin testing and clinical course suggested that the cause of these reactions was due to the excipient polysorbate 80. This finding might have implications in the recent increase in the incidence of pure red cell aplasia.

Adult↗

PubMed2004

Consensus guidelines on anti-cardiolipin antibody testing and reporting.

UNLABELLED: Consensus guidelines on anti-cardiolipin antibody (aCL) testing have been developed to help minimise laboratory variation in the performance and reporting of aCL assays. These guidelines include minimum, optimum and optional recommendations for the following aspects of aCL testing and reporting: (1) isotype of aCL tested; (2) specimen type; (3) controls and assay precision; (4) calibrators; (5) patient samples; (6) rheumatoid factors and IgM aCL testing; (7) reporting of results; (8) cut-off values; and (9) interpretative comments. ABBREVIATIONS: aCL, anti-cardiolipin antibodies; APS, anti-phospholipid antibody syndrome; ASCIA, Australasian Society of Clinical Immunology and Allergy; ASTH, Australasian Society of Thrombosis and Haemostasis; beta2-GPI=beta2-glycoprotein I; ELISA, enzyme-linked immunosorbent assay; NCCLS, National Committee for Clinical Laboratory Standards; HSANZ, Haematology Society of Australia and New Zealand; QAP, Quality Assurance Program; RCPA, Royal College of Pathologists of Australasia; %CV, inter-assay inter-run coefficient of variation.

Antibodies, Anticardiolipin↗

PubMed2003

Electromagnetic field generation by ATP-induced reverse electron transfer.

This paper describes a mechanism to explain low-level light emission in biology. A biological analog of the electrical circuitry, modeled on the parallel plate capacitor, traversed by a helical structure, required to generate electromagnetic radiation in the optical spectral range, is described. The charge carrier required for the emissions is determined to be an accelerating electron driven by an ATP-induced reverse electron transfer. The radial velocity component, the emission trajectory, of the moving charges traversing helical protein structures in a cyclotron-type mechanism is proposed to be imposed by the ferromagnetic field components of the iron in the iron-sulfur proteins. The redox systems NADH, riboflavin, and chlorophyll were examined with their long-wavelength absorption maxima determining the energetic parameters for the calculations. Potentials calculated from the axial velocity components for the riboflavin and NADH systems were found to equal the standard redox potentials of these systems as measured electrochemically and enzymatically. The mechanics for the three systems determined the magnetic moments, the angular momenta, and the orbital magnetic fluxes to be adiabatic invariant parameters. The De Broglie dual wave-particle equation, the fundamental equation of wave mechanics, and the key idea of quantum mechanics, establishes the wavelengths for accelerating electrons which, divided into a given radial velocity, gives its respective emission frequency. Electrons propelled through helical structures, traversed by biologically available electric and magnetic fields, make accessible to the internal environment the optical spectral frequency range that the solar spectrum provides to the external environment.

Adenosine Triphosphate↗

PubMed2003

Antibody and genetic testing in coeliac disease.

The description of a range of antibodies associated with coeliac disease has been an important development in the ability to test for this common and treatable condition non-invasively. However, the detection of these antibodies remains unstandardised and the appreciation of the clinical utility of each is evolving. In view of the advances in the diagnosis and understanding of coeliac disease, we discuss: (1) the relative advantages, disadvantages and comparative diagnostic utility of the different antibody tests including the confounding effect of selective IgA deficiency; (2) various technical aspects of these tests; (3) HLA-DQ typing as a supplementary tool to antibody testing; (4) areas of controversy resulting from insufficient or conflicting published data; and (5) potential testing strategies.

Autoantibodies↗

PubMed2002

Mean cell volume (MCV) changes in HIV-positive patients taking nucleoside reverse transcriptase inhibitors (NRTIs): a surrogate marker for adherence.

To assess whether changes in mean cell volume (MCV) could be used as a surrogate marker of adherence, the percentage rise from the baseline MCV (%MCV rise) was compared to an independent marker of adherence, the number of days of medications dispensed in a 24-week period. Nucleoside analogues were found to differ in the extent to which they affect the MCV. The correlation between zidovudine (AZT) (30 subjects) and stavudine (D4T) (41 subjects) with adherence based on prescriptions was 0.82 (P<0.05) and 0.55 respectively (P<0.05). When adherence was categorized into 10% intervals, there was a progressive rise in the average MCV with increasing adherence that plateaus at 70% adherence. Plotting %MCV rise on time charts appears to detect those subjects with adherence of less than 70%. In conclusion, changes in MCV for HIV-positive patients taking either AZT or D4T may be a useful surrogate marker for adherence to anti-retroviral medications.

Biomarkers↗