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 protein and peptide components in urine and lipopprotein specimens, and to develop methods for analysis of these components by matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometry. These studies showed the presence of a large number of small peptide components of the high-density lipoprotein fraction. The peptides represent small fragments of major plasma proteins, some of which are not commonly associated with lipoproteins. This may serve as a pathway for the clearance or delivery of protein degradation fragments, and the peptides accumulating on lipoproteins may serve as diagnostic markers for pathophysiological processes. Mass spectrometry is being examined as an analytical tool for the analysis of the peptide and small protein components in serum and plasma specimens with the goal of identifying new diagnostic markers. In a collaborative effort with the Department of Transfusion Medicine, we examined the ability to calibrate measurements by mass spectrometry by quantitative analysis of specific proteins by immunoassays. Our laboratory performed quantitative measures of glucosamine in support of studies by investigators in the National Center for Complementary Medicine examining whether this common dietary supplement promotes glucose intolerance. In urine specimens, there has been controversy about the ability of clinical assays for albumin to detect all forms or albumin in urine, and an alternative analytical method using size-exclusion liquid chromatography has been proposed as a method to measure modified forms of albumin with reduced immunoreactivity. Our studies showed that the chromatographic method is not specific for albumin, and provides overestimates of albumin excretion. Further study is underway to investigate the occurrence of modified forms of albumin in urine and how these interact with the immunoassays that are used for clinical detection of early stages of proteinuria. These studies seek to provide more accurate and sensitive detection of urinary protein excretion as a marker for early stages of kidney disease.
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