The LDL peak particle diameter was obtained from the nondenaturing 2% to 16% polyacrylamide gel electrophoresis of whole plasma, which was kept at −80°C before use, according to the procedure described by Krauss and Burke31 and by McNamara et al.32 Gels were cast in our laboratory using acrylamide and bisacrylamide (30.0:0.8) obtained from Bio-Rad (Hercules, Calif). A volume of 7.5 µL of plasma samples was applied on lanes in a final concentration of 20% sucrose and 0.25% bromophenol blue. Electrophoresis was performed in a refrigerated cell (10°C-15°C) for a prerun of 15 minutes at 125 V and for the entry of samples into stacking at 70 V, followed by migration at 200 V for 12 to 16 hours and finally at 400 V for 2 to 4 hours. Gels were stained for lipids overnight with sudan black (Lipostain, Paragon electrophoresis system; Beckman, Montreal, Quebec) in 55% ethanol. Gels were destained in a 45% ethanol solution, and original gel size was restored in a 9% acetic acid, 20% methanol solution. A plasma pool was used as an internal standard. Gels were analyzed using an optical densitometer image analyzer (Bio-Image Visage 110) coupled to a SPARC Station 2 Sun computer (Millipore, Ville St-Laurent, Quebec) and using GEL 1D software. Low-density lipoprotein peak particle size was obtained using the migration of standards of known diameter, such as ferritin (122 Å), thyroglobulin (170 Å), and 380-Å latex beads (Duke Scientific Corp, Palo Alto, Calif), and plasma standards of known diameter. Analyses of pooled plasma standards revealed that identification of the major LDL peak was highly reproducible, with an interassay coefficient of variation of less than 3% (B. Lamarche, PhD, A. Tchernof, PhD, S. Moorjani, PhD, et al, unpublished data, 1997).