title: Comparison of a direct enzymatic assay and polyacrylamide tube gel electrophoresis for measurement of small, dense low-density lipoprotein cholesterol.
abstract: BACKGROUND
  Small, dense low-density lipoprotein cholesterol (sdLDL-C) has been linked to the progression of cardiovascular disease. We compared two methods for determination of sdLDL-C, a direct enzymatic (ENZ) method and a polyacrylamide tube gel electrophoresis (PGE) assay, and investigated the associations of both sdLDL-C measurements with metabolic syndrome.
  
  
  METHODS
  We analyzed 242 patient sera for sdLDL and atherosclerosis-related markers. The PGE method separates the intermediate-density lipoprotein particles into three midbands (MID-A to MID-C) and the LDL particles into seven subfractions (LDL1 to LDL7); the sdLDL-PGE result is calculated as the sum of cholesterol concentrations from LDL3 to LDL7.
  
  
  RESULTS
  The regression equation for sdLDL-C was [ENZmmol/L]=0.779[PGE]+0.67, r=0.713. ENZ showed higher sdLDL-C concentrations than PGE (0.86±0.33 vs. 0.24±0.32 mmol/L); however, the difference was not associated with sdLDL-C concentration (p=0.290). sdLDL-C, as measured with the enzymatic assay, exhibited significant positive correlations with very-low-density lipoprotein, MID-C, MID-B, and LDL2 (all p<0.001), considered atherogenic lipoproteins, but did not correlate with the less atherogenic lipoproteins MID-A and LDL1 (all p>0.600). The ENZ and PGE methods yielded similar patterns of correlation between sdLDL-C, and atherosclerosis-related markers. Using logistic regression, sdLDL-ENZ and apolipoprotein B were identified as significant predictors of metabolic syndrome (p<0.03).
  
  
  CONCLUSIONS
  The ENZ assay for sdLDL-C correlated well with the PGE method. The ENZ method measures a broader range of atherogenic lipoprotein particles than PGE and has the potential to identify subjects with vascular risk, thus contributing in directing specific interventions for cardiovascular prevention.
authors.forename: Somlak
authors.initials: S
authors.lastname: Vanavanan
authors.forename: Pornpen
authors.initials: P
authors.lastname: Srisawasdi
authors.forename: Mana
authors.initials: M
authors.lastname: Rochanawutanon
authors.forename: Jirapa
authors.initials: J
authors.lastname: Kerdmongkol
authors.forename: Martin H
authors.initials: MH
authors.lastname: Kroll
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods*; D002318:Cardiovascular Diseases / Q000150:complications; D008078:Cholesterol, LDL / Q000097:blood* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods*; D004798:Enzymes / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000150:complications; D008875:Middle Aged; D012306:Risk
chemical_list: D008078:Cholesterol, LDL; D004798:Enzymes