TY - JOUR
T1 - Delta-S-cys-albumin
T2 - A lab test that quantifies cumulative exposure of archived human blood plasma and serum samples to thawed conditions
AU - Jeffs, Joshua W.
AU - Jehanathan, Nilojan
AU - Thibert, Stephanie M.F.
AU - Ferdosi, Shadi
AU - Pham, Linda
AU - Wilson, Zachary T.
AU - Breburda, Christian
AU - Borges, Chad R.
N1 - Funding Information:
* This work was supported by ASU faculty start-up funds (CRB) and the National Cancer Institute of the National Institutes of Health under award no. R33 CA217702-01A1 (CRB). □S This article contains supplemental Figures and Tables. ‖ To whom correspondence should be addressed. The Biodesign Institute at Arizona State University, P.O. Box 876401, Tempe, AZ 85287. Tel.: 480-727-9928; E-mail: chad.borges@asu.edu.
Funding Information:
There is widespread agreement regarding the need for robust biospecimen quality control (QC)/quality assurance (QA) checks in biomarker discovery and validation work. Yet relatively little research effort focuses on this arena. P/S specimens are among the most commonly employed biospeci-mens in biomarker-related research but, to date, no gold standard marker of P/S integrity has been identified and put into widespread, routine use. This is evidenced by the fact that despite the recent emphasis on robustness and reproducibility, the U.S. National Cancer Institute (NCI, part of the National Institutes of Health) does not currently require any empirical evidence-based QA thresholds be met before pre-existing P/S specimens are employed in NCI-sponsored research. This QC/QA problem is widespread: In 2014, for example, out of 455 NCI-sponsored extramural grants that involved biospecimens, 287 (63%) relied on pre-existing samples; over 100 of these sponsored projects employed pre-existing P/S (12).
Funding Information:
* This work was supported by ASU faculty start-up funds (CRB) and the National Cancer Institute of the National Institutes of Health under award no. R33 CA217702-01A1 (CRB).
Publisher Copyright:
© 2019 Jeffs et al. Published by The American Society for Biochemistry and Molecular Biology, Inc.
PY - 2019
Y1 - 2019
N2 - Exposure of blood plasma/serum (P/S) to thawed conditions (> -30 °C) can produce biomolecular changes that skew measurements of biomarkers within archived patient samples, potentially rendering them unfit for molecular analysis. Because freeze-thaw histories are often poorly documented, objective methods for assessing molecular fitness before analysis are needed. We report a 10-μl, dilute-and-shoot, intact-protein mass spectrometric assay of albumin proteoforms called “Δ S-Cys-Albumin” that quantifies cumulative exposure of archived P/S samples to thawed conditions. The relative abundance of S-cysteinylated (oxidized) albumin in P/S increases inexorably but to a maximum value under 100% when samples are exposed to temperatures > -30 °C. The difference in the relative abundance of S-cysteinylated albumin (S-Cys-Alb) before and after an intentional incubation period that drives this proteoform to its maximum level is denoted as Δ S-Cys-Albumin. Δ S-Cys-Albumin in fully expired samples is zero. The range (mean ± 95% CI) observed for Δ S-Cys-Albumin in fresh cardiac patient P/S (n = 97) was, for plasma 12-29% (20.9 ± 0.75%) and for serum 10 -24% (15.5 ± 0.64%). The multireaction rate law that governs S-Cys-Alb formation in P/S was determined and shown to predict the rate of formation of S-Cys-Alb in plasma and serum samples-a step that enables back-calculation of the time at which unknown P/S specimens have been exposed to room temperature. A blind challenge demonstrated that Δ S-Cys-Albumin can detect exposure of groups (n = 6 each) of P/S samples to 23 °C for 2 h, 4 °C for 16 h, or -20 °C for 24 h-and exposure of individual specimens for modestly increased times. An unplanned case study of nominally pristine serum samples collected under NIH-sponsorship demonstrated that empirical evidence is required to ensure accurate knowledge of archived P/S biospecimen storage history.
AB - Exposure of blood plasma/serum (P/S) to thawed conditions (> -30 °C) can produce biomolecular changes that skew measurements of biomarkers within archived patient samples, potentially rendering them unfit for molecular analysis. Because freeze-thaw histories are often poorly documented, objective methods for assessing molecular fitness before analysis are needed. We report a 10-μl, dilute-and-shoot, intact-protein mass spectrometric assay of albumin proteoforms called “Δ S-Cys-Albumin” that quantifies cumulative exposure of archived P/S samples to thawed conditions. The relative abundance of S-cysteinylated (oxidized) albumin in P/S increases inexorably but to a maximum value under 100% when samples are exposed to temperatures > -30 °C. The difference in the relative abundance of S-cysteinylated albumin (S-Cys-Alb) before and after an intentional incubation period that drives this proteoform to its maximum level is denoted as Δ S-Cys-Albumin. Δ S-Cys-Albumin in fully expired samples is zero. The range (mean ± 95% CI) observed for Δ S-Cys-Albumin in fresh cardiac patient P/S (n = 97) was, for plasma 12-29% (20.9 ± 0.75%) and for serum 10 -24% (15.5 ± 0.64%). The multireaction rate law that governs S-Cys-Alb formation in P/S was determined and shown to predict the rate of formation of S-Cys-Alb in plasma and serum samples-a step that enables back-calculation of the time at which unknown P/S specimens have been exposed to room temperature. A blind challenge demonstrated that Δ S-Cys-Albumin can detect exposure of groups (n = 6 each) of P/S samples to 23 °C for 2 h, 4 °C for 16 h, or -20 °C for 24 h-and exposure of individual specimens for modestly increased times. An unplanned case study of nominally pristine serum samples collected under NIH-sponsorship demonstrated that empirical evidence is required to ensure accurate knowledge of archived P/S biospecimen storage history.
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U2 - 10.1074/mcp.TIR119.001659
DO - 10.1074/mcp.TIR119.001659
M3 - Article
C2 - 31324658
AN - SCOPUS:85072848947
SN - 1535-9476
VL - 18
SP - 2121
EP - 2137
JO - Molecular and Cellular Proteomics
JF - Molecular and Cellular Proteomics
IS - 10
ER -