Goals of this project are to improve clinical laboratory methods for diagnosis of disease. Studies include analysis of clinical laboratory practices, analysis of the accuracy of laboratory tests, and development of new tests and testing technologies. The major efforts over the past year have been to examine methods for specimen collection and processing to analyze protein components in blood and urine specimens and to analyze protein components in urine. Collaborative efforts examined polymeric components eluted from blood collection tubes that may yield additional peaks during analysis of specimens by mass spectrometric analysis. Studies showed interference of additives in blood collection tubes with a number of immunoassays that are commonly used in clinical laboratories. The basic mechanism of this interference by surfactants added to blood collection tubes was determined and it should lead to improved blood collection products and quality of clinical immmunoassay results in many laboratories. There has been controversy among previously published reports about the amounts of peptide components excreted in urine. Our laboratory performed a detailed analysis of one method used for urinary peptide analysis, the biuret method. We identified a variety of nonpeptide materials that serve as potential interferents in the analysis of urinary peptide content and suggest that some previous reports provide falsely high estimates of peptide excretion. This assay appeared to serve as a method for quantifying peptides of 3 residues or more in length, but some fractionation is required to remove interfering materials before analysis. Development of better methods for quantification of total peptide content in mixtures is one important step in the quantitative analysis of complex mixtures for peptidomic analysis. Ongoing studies are examining the accuracy of size-exclusion high-performance liquid chromatography as a method for analysis of urinary albumin and other urinary protein components. Efforts are continuing to develop standard protocols for the analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of the diverse range of peptide components in urine and subfractions of blood. In collaborative efforts with the Department of Transfusion Medicine, we have examined the ability to calibrate measurements by mass spectrometry by quantitative analysis of specific components by immunoassay.
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