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Effect of storage at -70 degrees C on lipid, lipoprotein and apolipoprotein concentrations.

Author(s): Evans K, Mitcheson J, Laker MF

Publication: Clin Chim Acta, 1997, Vol. 258, Page 219-29

PubMed ID: 9074818 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to determine the effects of frozen storage of serum on levels of total cholesterol, triglycerides, Apo AI and Apo B and the lipoprotein fractions after ultracentrifugation. Blood was collected after a 12 h fast with minimal venous stasis and a cocktail of EDTA and protease inhibitors in ethanol was added to serum prior to freezing.

   Summary of Findings:

   Total cholesterol, triglycerides, Apo AI and Apo B levels changed by less than 4% in total serum during storage for up to 6 months at -70 degrees C, but the <2% increase in triglycerides was significant (p=0.007). Free cholesterol and phospholipid levels decreased by 13 and 10%, respectively, in the very low density lipoprotein (VLDL) fraction after storage of unfractionated serum at -70 degrees C. Further, esterified, free and total cholesterol and phospholipid levels in the low density lipoprotein (LDL) fraction decreased when serum was stored at -70 degrees for 10 days, but were comparable or higher than the levels measured in fresh specimens when serum was stored for 3 or 6 months. Protein levels decreased in the LDL fraction when serum was stored frozen at -70 degrees C. None of the analytes in the intermediate density lipoprotein (IDL) fraction were significantly affected by storage of serum at -70 degrees C.

   Biospecimens

   • Bodily Fluid - Serum

   Preservative Types

   • Frozen
   • None (Fresh)

   Diagnoses:

   • Not specified
   • Other diagnoses

   Platform:

   Analyte	Technology Platform
   Lipid	Clinical chemistry/auto analyzer
   Lipid	Colorimetric assay
   Lipoprotein	Clinical chemistry/auto analyzer
   Lipoprotein	Colorimetric assay
   Steroid	Clinical chemistry/auto analyzer
   Steroid	Colorimetric assay
   Protein	Clinical chemistry/auto analyzer
   Protein	Lowry protein assay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage duration	<3 days 10 days 3 months 6 months
   Biospecimen Preservation	Type of fixation/preservation	Frozen None (fresh)
   Preaquisition	Diagnosis/ patient condition	Normolipidaemic Hyperlipidaemic

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