Comparison of the susceptibility of serum lipoproteins to oxidation and the effects of high-density lipoprotein against oxidative stress in patients with lipid turbulence / 医学研究生学报

ABSTRACT

Objectives:To compare the susceptibility of serum lipoproteins to oxidation and the effects of high-density lipoprotein on oxidative stress in patients with lipid turbulence.　Methods:VLDL, LDL and HDL were isolated using sequential ultracentrifugation from serum of patients with chronic renal failure (CRF) (n=45), myocardial infarction survivor (MIS) (n=33) , cerebral infarction(CI)(n=33) ,type 2 diabetes mellitus(DM)(n=53) and normal individuals (n=44). The degree of lipid peroxidation was estimated using the thiobarbituric acid-reactive substances (TBARS) value and the susceptibilities of lipoproteins to oxidation were assessed by measuring the increased absorbance value at 234 nm due to the conjugated dinene formation. Lipid levels and lipoprotein fractions were measured using standard methods.　Results: VLDL obtained from the patient groups showed significant increase in TBARS values, especially from the patients with MIS (compared with control group, P<0.001). In addition, LDL from MIS and DM groups and HDL from CI and DM groups also showed markedly increase in TBARS content. Significant decrease in lag time was observed in both VLDL and LDL fractions from the four patient groups. However, no change was found in the lag time in HDL fraction from the patient group compared with control group. In addition, HDL from the four patients exhibited significantly decreased inhibitory effects on in vitro oxidation of LDL, with the most significant decrease in HDL from CRF and MIS groups.　 Conclusions:The oxidative modification of lipoproteins in vivo in patients with serum lipid turbulence might be involved in the development of atherosclerosis in these patients.