[Stability of lipid and protein composition of very low-density lipoproteins during the storage after freezing of whole serum and isolated lipoproteins (author's transl)].

The lipid and protein composition of lipoprotein is now regarded with great interest for the identification of hyperlipoproteinemias. Because this relatively time-consuming study cannot be envisaged currently in clinical services, it seems useful to analyse a storage procedure which does not affect the composition of very-low density lipoproteins, whose proportion is very important among subjects with type IV hyperlipoproteinemia. Two studies were considered, one using whole sera stored at -20 degrees C and one using very low-density lipoproteins held in the same conditions. The lipid composition was determined for triglycerides and cholesterol concentrations of total proteins, proteins soluble in tetramethylurea (apoprotein C, "arginine-rich fraction", and apoprotein D), and peptides CII, CIII1 and CIII2 of apoprotein C. For both procedures considered, no significant changes were seen in lipid and protein composition for periods as long as 8 weeks.