Abstract
Small-dense low-density lipoprotein (SD-LDL) is associated with coronary heart disease risk. Current methods for its quantification are expensive, complex and time-consuming. Plasma was adjusted to a density (D) of 1.044 g/ml in a volume of 0.18 ml and centrifuged in a Beckman Airfuge at 160 000×g for 3 h 7 min and apolipoprotein B (apoB) then determined in the infranatant. Results were compared with centrifugation of 5 ml of plasma at D=1.044 g/ml at 144 000×g for 18 h in a preparative ultracentrifuge (UC). We obtained blood samples from healthy subjects (n=73) and from dyslipidaemic patients (n=112). SD-LDL apoB levels as determined using the UC method ranged from 0.01–0.43 g/l and there was a good correlation with Airfuge results (r=0.925; p<0.0001; n=185). There was a mean difference of 0.0125 g/l between methods. SD-LDL apoB levels as determined using the Airfuge showed a reasonable agreement with results obtained using density gradient ultracentrifugation (r=0.773; p<0.01; n=12). Airfuge results correlated directly with triglyceride concentration, in both healthy men (r=0.296; p<0.05) and dyslipidaemic men (r=0.520; p<0.001) and also in dyslipidaemic women (r=0.463; p<0.005). Airfuge results correlated inversely with high-density lipoprotein-cholesterol (HDL-C) concentration, in both healthy men (r=−0.237; p<0.05) and dyslipidaemic men (r=−0.293; p<0.005). Using a micro-method, we obtained results which establish that the Airfuge provides a more rapid and less expensive method for quantification of SD-LDL.
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