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Kenilworth, NJ, United States

McAvoy T.,Lincoln Laboratory | Lassman M.E.,Lincoln Laboratory | Spellman D.S.,Molecular Biomarkers | Ke Z.,Molecular Biomarkers | And 6 more authors.
Clinical Chemistry

BACKGROUND: Cerebrospinal fluid (CSF) tau is a common biomarker for Alzheimer disease (AD). Measurements of tau have historically been performed using immunoassays. Given the molecular diversity of tau in CSF, the selectivity of these immunoassays has often been questioned. Therefore, we aimed to develop an analytically sensitive and selective immunoaffinity liquid chromatography-tandem mass spectrometry (LCMS/ MS) (IA-MS) assay.METHODS: IA-MS sample analysis involved the additionof an internal standard, immunoaffinity purification of tau using a tau monoclonal antibody coupled to magnetic beads, trypsin digestion, andquantification of a surrogate tau peptide by LCMS/ MS using a Waters Trizaic nanoTile ultraperformanceLC microfluidic device. Further characterization of tau peptides was performed by full-scan MS using a Thermo Orbitrap LC-MS. CSF samples from a cohort of age-matched controls and patients withAD were analyzed by the IA-MS method as well as a commercially available immunoassay. RESULTS: The IA-MS assay had intra- and interassay imprecision values of 3.2% to 8.1% CV and 7.8% to18.9% C, respectively, a mean recovery of 106%, and a limit of quantification of 0.25 pmol/L and was able to quantify tau concentrations in all human specimens tested. The IA-MS assay showed a correlation of R2 = 0.950 against a total-tau immunoassay. In patients withAD, tau was increased approximately 2-fold. CONCLUSIONS: Combining immunoaffinity enrichment with microflow LC-MS/MS analysis is an effective approach for the development of a highly selective assay to measure total tau and, potentially, other posttranslationally modified forms of tau in CSF. ©2014 American Association for Clinical Chemistry. Source

Previs S.F.,Molecular Biomarkers | McLaren D.G.,Molecular Biomarkers | Wang S.-P.,Molecular Biomarkers | Stout S.J.,Molecular Biomarkers | And 9 more authors.
Biochimica et Biophysica Acta - Molecular Basis of Disease

Our ability to understand the pathogenesis of problems surrounding lipid accretion requires attention towards quantifying lipid kinetics. In addition, studies of metabolic flux should also help unravel mechanisms that lead to imbalances in inter-organ lipid trafficking which contribute to dyslipidemia and/or peripheral lipid accumulation (e.g. hepatic fat deposits). This review aims to outline the development and use of novel methods for studying lipid kinetics in vivo. Although our focus is directed towards some of the approaches that are currently reported in the literature, we include a discussion of the older literature in order to put "new" methods in better perspective and inform readers of valuable historical research. Presumably, future advances in understanding lipid dynamics will benefit from a careful consideration of the past efforts, where possible we have tried to identify seminal papers or those that provide clear data to emphasize essential points. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease. © 2013 Elsevier B.V. Source

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