Ito Y, Nakachi K, Imai K, Hashimoto S, Watanabe Y, Inaba Y, Tamakoshi A, Yoshimura T. Stability of frozen serum levels of insulin-like growth factor-I, insulin-like growth factor-II, insulin-like growth factor binding protein-3, transforming growth factor beta, soluble Fas, and superoxide dismutase activity for the JACC study.
J Epidemiol 2005;
15 Suppl 1:S67-73. [PMID:
15881197 PMCID:
PMC8565868 DOI:
10.2188/jea.15.s67]
[Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND: Subjects of the Japan Collaborate Cohort Study (JACC Study) gave peripheral blood samples collected between 1988 and 1990. We conducted to investigate whether levels of serum components measured after 9 years of frozen storage are stable or not.
METHODS: To assess the degradation of frozen serum components in the JACC Study, we compared levels of various components (IGF-I, IGF-II, IGFBP-3, TGF-β1, sFas, and total SOD activity) between fresh and stored sera collected from other inhabitants. Serum levels of constituents were measured by immunoradiometric assay (IGF-I, IGF-II and IGFBP-3), quantitative enzyme immunoassay (TGF-β1), enzyme-linked immuno-adsorbent assay (sFas), and an improved nitrite method (SOD activity).
RESULTS: The coefficients of variation for intra- and inter-assay precisions of the measurements were less than 9%. Levels of IGF-I, IGF-II, IGFBP-3, TGF-β1 and sFas in sera after storage for 9 years at -80°C were similar to those of fresh sera newly collected from inhabitants. The distributions of serum IGF-I, IGF-II, IGFBP-3, TGF-β1, sFas and SOD activity for specimens collected from different individuals tended to be similar to those of serum levels for frozen specimens collected from different individuals and stored for 9 years.
CONCLUSIONS: There was no statistically significant difference in distribution of measured values of IGF-I, IGF-II, IGFBP-3, TGF-β1, and sFas between newly collected sera and frozen specimens stored for 9 years. Thus, measurements of these serum constituents of specimens stored for the JACC Study can be reliably used in nested case-control study.
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