Prostate specific antigen (PSA) is the marker of choice in the management of prostate cancer. However, PSA is not a simple molecule, existing in the serum in five isoforms and a number of molecular configurations and ...
详细信息
Prostate specific antigen (PSA) is the marker of choice in the management of prostate cancer. However, PSA is not a simple molecule, existing in the serum in five isoforms and a number of molecular configurations and complexes. The elucidation of the biochemistry of PSA has increased the potential use of the marker in the diagnosis of prostate malignancy. This review summarizes the clinical use of PSA in the management of prostate disease and the assays available in the UK. Assay calibration in relation to the World Health Organization Ist International Standard for Prostate Specific Antigen (90:10) has increased conformity between the various commercial assay kits, and the non-equimolar kits have largely been superseded or withdrawn. Special reference is made to evaluations performed on behalf of the Medical Devices Agency of the Department of Health.
We developed an improved enzymatic assay of D-sorbitol in human erythrocytes by employing highly specific D-sorbitol dehydrogenase from Pseudomonas sp. (EC 1.1.1.14) and replacing perchloric acid (HClO4) and potassium...
详细信息
We developed an improved enzymatic assay of D-sorbitol in human erythrocytes by employing highly specific D-sorbitol dehydrogenase from Pseudomonas sp. (EC 1.1.1.14) and replacing perchloric acid (HClO4) and potassium carbonate (K2CO3), generally used for deproteinization, with sodium hydroxide (NaOH) and zinc sulphate (ZnSO4). In this assay, erythrocytes were separated from plasma by centrifugation and washed once with physiological saline. Subsequently, the erythrocytes were lysed with distilled water and proteins precipitated with NaOH and ZnSO4. After centrifugation, the resulting colourless supernatant was mixed with a glycine buffer (pH 9.0) containing NAD(+) and D-sorbitol dehydrogenase. After incubation for 30 min at 37 degreesC, the NADH produced was measured fluorimetrically. The fluorescence intensities were corrected for sample blanks, and the values of D-sorbitol were normalized for haemoglobin content. The method had an analytical range of 1-180 mu mol/L. The intra- and inter-assay precisions were < 3.3% and < 5.8%, respectively. The detection limit was 0.65 mu mol/ L. In terms of the linearity, precision and sensitivity, the improved method using NaOH and ZnSO4 was superior to the conventional method using HClO4 and K2CO3.
We have evaluated a tandem mass spectrometry method for determining free carnitine concentrations in plasma and have compared its performance with that of an existing radioenzymatic assay. In this method, plasma was m...
详细信息
We have evaluated a tandem mass spectrometry method for determining free carnitine concentrations in plasma and have compared its performance with that of an existing radioenzymatic assay. In this method, plasma was mixed with an internal standard, carnitine-d(3) (600 nmol/L), and butylated before analysis on a Quattro II tandem mass spectrometer. The detection limit of the tandem mass spectrometric (MS) method was 4 mu mol/L and carryover between samples was 2.2%. Precision of the method was 1.6 5.4% between injections and 4.0-5.6% between samples. Between batch precision was 10 13%. The method was linear up to a free carnitine concentration of 300 mu mol/L and good agreement was found with the existing radioenzymatic assay. We conclude that the tandem MS method is a precise and robust method for the determination of free carnitine concentrations in plasma that overcomes the disadvantages of the radiochemical method.
暂无评论