Autoantibodies against cardiac troponin I in patients with congestive heart failure.

AIMS: In this randomized, double-blind clinical study, we investigated the relationship between autoantibodies against cardiac troponin I (cTnI) and disease severity in elderly congestive heart failure (CHF) patients before and after titration of beta-blocker therapy. METHODS AND RESULTS: Anti-cTnI, cTnI, and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels in blood from 138 patients (73 +/- 5.6 years, 48% male) with CHF in American Heart Association stages A-C were measured at baseline and after titration of beta-blockers to maximal tolerated dose. Median follow-up period was 85 days. Anti-cTnI was measured using an experimental assay (Abbott Diagnostics) and is expressed as a relative value unit (RVU) in relation to the mean value of a low-level control sample. Anti-cTnI values in CHF patients were also compared with measurements taken in a normal reference population of 300 healthy individuals (50% male). Cardiac troponin I and NT-proBNP levels were measured using routine assays (Architect Abbott Diagnostics and Roche Diagnostics). Median anti-cTnI was 0.53 and 0.56 RVU in healthy and CHF subjects, respectively (P = n.s.), and increased significantly to 0.67 RVU (P < 0.001) after beta-blocker titration. Mean cTnI values were 0.021 microg/L at baseline and fell significantly to 0.0046 microg/L at follow-up (P < 0.001). Median NT-proBNP values were 352 ng/L at baseline and 414 ng/L after titration (P = n.s.). In contrast to NT-proBNP and cTnI, anti-cTnI was not associated with the severity of CHF at baseline or follow-up. CONCLUSION: Levels of anti-cTnI tend to increase in elderly patients with CHF following titration of beta-blocker therapy but do not correlate with disease severity. Anti-cTnI is not a useful biomarker for heart failure diagnosis, prognosis, or monitoring. In contrast, levels of cTnI decreased following therapy and did correlate with disease severity.

Toward metrological traceability in the determination of prostate-specific antigen (PSA): calibrating Beckman Coulter Hybritech Access PSA assays to WHO standards compared with the traditional Hybritech standards.

BACKGROUND: The metrological traceability of prostate-specific antigen (PSA) assay calibration to WHO standards is desirable to potentially improve the comparability between PSA assays. A method comparison was performed between the traditionally standardized Beckman Coulter Hybritech Access PSA and free PSA (fPSA) assays and a new alternate calibration of assays aligned to the WHO standards 96/670 and 96/668, respectively. METHODS: Sera from 641 men with and without prostate cancer, various control materials and mixtures of different proportions of the WHO standards were measured with both assay calibrations. RESULTS: Excellent comparability between the corresponding assay calibrations was observed, with correlation coefficients of at least 0.996. The Passing-Bablok slopes were 0.747 for total PSA (tPSA), 0.776 for fPSA and 1.02 for the percentage ratio of fPSA to tPSA (%fPSA), while the corresponding percentages of the new WHO-aligned assay results related to the traditional assays were 76.2%, 77% and 102.2%. Receiver operating characteristics revealed no differences between the two PSA assay calibrations. CONCLUSIONS: The WHO calibration yields results approximately 25% lower for tPSA and fPSA values when compared with the conventional Hybritech calibration. Using the WHO-aligned PSA assay, a tPSA cut-off of 3 microg/L should be considered in clinical practice, while %fPSA cut-offs could be retained.

Free PSA forms in prostatic tissue and sera of prostate cancer patients: analysis by 2-DE and western blotting of immunopurified samples.

OBJECTIVE: The isoform pattern of free prostate-specific antigen (fPSA) from sera of patients with prostate cancer (PCa) and no evidence of prostate cancer (NPCa), cancerous and non-cancerous tissues and seminal plasma, have been compared, above all regarding the degree of sialylation, with the aim to show a better discrimination of PCa and NPCa. DESIGN AND METHODS: The samples have been immunopurified and analyzed by two dimensional gel electrophoresis and western blotting. It was investigated which patterns were obtained when looking for the fPSA and the (-5/-7)proPSA (precursor form) before and after desialylation. RESULTS: The fPSA sialylation and the proPSA pattern in cancerous and non-cancerous prostate tissues were similar to each other and only slightly different from PCa and NPCa sera. The different fPSA isoforms observed could not be due solely to differences in the degree of sialylation, because different fPSA and (-5/-7)proPSA precursor isoforms were still present after complete desialylation. CONCLUSIONS: Although slight differences in the fPSA and (-5/-7) proPSA glycosylation and isoform pattern were observed, they were not large enough to be considered to improve PCa diagnosis.

Analysis of subforms of free prostate-specific antigen in serum by two-dimensional gel electrophoresis: potential to improve diagnosis of prostate cancer.

BACKGROUND: The aim of this study was to develop a method to separate and quantify subforms of free prostate-specific antigen (fPSA) in serum by two-dimensional electrophoresis and to assess the diagnostic accuracy of these subforms for prostate cancer (PCa) diagnosis in comparison with total PSA (tPSA) and the ratio of fPSA to tPSA (%fPSA). METHODS: Sera from 50 patients with and without PCa, respectively, were studied. PSA was isolated by immunoadsorption on streptavidin-coated magnetic beads with biotinylated anti-PSA antibodies and separated by two-dimensional electrophoresis. After semidry blotting, the intensities of the fPSA spots were quantified by chemiluminescence using an imager analyzer. RESULTS: The method detected subforms to a concentration of 0.1 mug/L fPSA with an imprecision (CV) <16%. We detected 15 immunoreactive fPSA spots of different intensities. Spots F2 and F3 were present in all samples. F2 was lower in samples from non-PCa patients (median, 23%) than in samples from PCa patients (49%), whereas F3 behaved inversely (non-PCa, 73%; PCa, 45%). Ratios of F2 to F3 and F2/F3 to %fPSA, respectively, showed improved diagnostic accuracy compared with tPSA and %fPSA. Better differentiation by F2/F3 or by F2/F3 to %fPSA was particularly evident in patients with %fPSA values >15%. There were no associations between the PCa grading scale and fPSA subforms. CONCLUSIONS: fPSA subforms separated by two-dimensional electrophoresis may improve both sensitivity and specificity in prostate cancer diagnostics compared with tPSA and %fPSA. The development of a practicable assay based on the immunologic properties of these different fPSA subforms seems to be promising.