A simple and precise method for direct measurement of fractional esterification rate of high density lipoprotein cholesterol by high performance liquid chromatography.
BACKGROUND
The relationship between fractional cholesterol esterification rate in plasma or serum high-density lipoprotein (HDL) (FER(HDL)) and lipoprotein subfractions and other cardiovascular disease (CVD) risk factors has been demonstrated. However, the current method for measuring FER(HDL) requires fresh serum samples and radioactive labeling of the samples, making it impractical for use in clinical laboratories. In this study, we developed a simple and precise HPLC method for the measurement of FER(HDL). Correlations between FER(HDL) and CVD risk factors were evaluated in 119 healthy volunteers.


METHODS
Fasting blood samples were collected and serum was isolated within 2 h. Serum HDL was prepared by precipitation of apolipoprotein B (apoB)-containing lipoproteins with dextran sulfate and magnesium chloride. HDL fractions were divided into two aliquots and incubated at 0°C and 37°C, respectively, for 1 h. Free cholesterol in the HDL fractions was analyzed by HPLC. FER(HDL) was calculated as the percent decrease of free cholesterol during incubation.


RESULTS
The esterification reaction of HDL free cholesterol was not linear, but the measured FER(HDL) was stable when serum samples were stored at room temperature for <4 h, or at 4°C for <24 h. The intra-assay and total CVs for FER(HDL) measurements were 1.0%-2.1% and 1.6%-3.8%, respectively. Results of 119 healthy volunteers showed that FER(HDL) was positively correlated with age, BMI, blood pressure, total cholesterol (TC), triglyceride (TG) and small dense low-density lipoprotein-cholesterol (LDLb-C), and negatively correlated with HDL-C and HDL2-C. FER(HDL) has shown to be a predictor of HDL and LDL subfraction distributions.


CONCLUSIONS
This method is simple, non-radioactive and precise and will be useful in prediction of lipoprotein subfraction distributions and in clinical assessment of CVD risks.
Jun
J
Dong
Songlin
S
Yu
Ruiyue
R
Yang
Hongxia
H
Li
Hanbang
H
Guo
Haijian
H
Zhao
Shu
S
Wang
Wenxiang
W
Chen
D000328:Adult; D000368:Aged; D008076:Cholesterol, HDL / Q000097:blood* / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004951:Esterification; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D055815:Young Adult
D008076:Cholesterol, HDL