Total serum cholesterol concentration and lipoprotein-cholesterol distribution were analyzed as previously described[12 (link),21 (link)]. Briefly, total serum cholesterol was measured by enzymatic colorimetric method using the Wako Cholesterol E kit (Wako Chemicals USA). Lipoprotein-cholesterol distribution was detected by size exclusion chromatography using a fast performance liquid chromatographic machine (Pharmacia LKB Biotechnology, Uppsala, Sweden).