Browsing by Subject "Screening test"

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    Hepatitis C virus infection rate in volunteer blood donors from the Western Cape : comparison of screening tests and PCR
    (1997) Tucker, TJ; Voigt, M; Bird, A; ROBSON, S; Gibbs, B; KANNEMEYER, J; Galloway, M; Kirsch, AE; SMUTS, H
    INTRODUCTION: Hepatitis C virus (HCV) antibody seroprevalence studies overestimate the true infection rate. No data exist on the incidence of HCV or its clinical features in blood donors of sub-Saharan Africa. AIMS: To establish the true incidence of HCV infection in volunteer blood donors in the Western Cape, and compare risk factors and clinical and biochemical features of viraemic and non-viraemic subjects. METHODS: All donors attending the Western Province Blood Transfusion Service between December 1992 and August 1994 were screened prospectively for anti-HCV using the Abbott second-generation assay. Positive donors were evaluated clinically and biochemically. Their sera were examined for HCV-RNA by the polymerase chain reaction (PCR). RESULTS: Of 66314 donors screened, 275 (0.41%) were anti-HCV-positive. Of these 13.6% were PCR-positive (0.056% of all donors). PCR-positive patients had more risk factors for HCV acquisition (P < 0.01), symptoms of hepatitis (P = 0.02) and clinical signs of liver disease (P = 0.05) and higher alanine (P < 0.0001) and aspartate aminotransferase levels (P < 0.0001) than PCR-negative donors. However, clinical and biochemical features did not discriminate adequately between PCR-positive and negative donors. Liver biopsies performed in 9 of 13 PCR-positive cases showed mild inflammation, but no cirrhosis.
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    A modified pH drift assay for inorganic carbon accumulation and external carbonic anhydrase activity in microalgae
    (Springer, 2014) van Hille, R; Fagan, M; Bromfield, L; Pott, R
    Threat of global warming due to carbon dioxide (CO2) emissions has stimulated research into carbon sequestration and emissions reduction technologies. Alkaline scrubbing allows CO2 to be captured as bicarbonate, which can be photochemically fixed by microalgae. The carbon concentrating mechanism (CCM), of which external carbonic anhydrase is a key component, allows organisms to utilise this bicarbonate. In order to select a suitable strain for this application, a screening tool is required. The current method for determining carbonic anhydrase activity, the Wilbur and Anderson assay, was found to be unsuitable as a screening tool as the associated error was unacceptably large and tests on whole cells were inconclusive. This paper presents the development of a new, whole cell assay to measure inorganic carbon uptake and external carbonic anhydrase activity, based on classical pH drift experiments. Spirulina platensis was successfully used to develop a correlation between the specific carbon uptake (C) and the specific pH change (dpH). The relationship is described by the following: C[mmol C (g dry algae)−1 h−1] = 0.064 × (dpH). Inhibitor and salt dissociation tests validated the activity and presence of external carbonic anhydrase and allowed correlation between the Wilbur and Anderson assay and the new whole cell assay. Screening tests were conducted on S. platensis, Scenedesmus sp., Chlorella vulgaris and Dunaliella salina that were found to have carbon uptake rates of 5.76, 5.86, 3.86 and 2.15 mmol C (g dry algae)−1 h−1, respectively. These results corresponded to the species' known bicarbonate utilisation abilities and validated the use of the assay as a screening tool.