Relationship between triglyceride concentrations and LDL size evaluated by malondialdehyde-modified LDL.
BACKGROUND
Hypertriglyceridemia is associated with decreased HDL-cholesterol (HDL-C) and increased small dense LDL. In addition, small dense LDL is known to be susceptible to oxidation.


METHODS
We measured LDL particle size, using gradient gel electrophoresis, and malondialdehyde-modified LDL (MDA-LDL), using an ELISA, and investigated the association between triglyceride (TG) concentrations, LDL size, and MDA-LDL.


RESULTS
TG concentrations correlated negatively with the predominant LDL size (r = -0.650) and HDL-C concentration (r = -0.556). The relationship between TG concentration and LDL size, evaluated by measuring MDA-LDL, distinguished subgroups derived from four subfractions of TG concentrations and four distribution ranges of LDL size. These experiments indicated that there is a threshold for oxidation susceptibility at an LDL size of 25.5 nm and a TG concentration of 1500 mg/L. To investigate the relationship between LDL size, MDA-LDL concentration, and other lipids (TGs, HDL-C, apolipoprotein B, and total cholesterol), we evaluated them in control subjects and patients with diabetes mellitus or hypertriglyceridemia. When the size range for normal LDL was postulated to be 25.5 < or = phi (LDL diameter) < 26.5 nm, the MDA-LDL concentration was significantly higher in the subgroups of patients with LDL in the size range 24.5 < or = phi < 25.5 nm compared with patients with normal LDL. This result also suggests that the threshold is at a LDL size of 25.5 nm.


CONCLUSIONS
The threshold for oxidation susceptibility coincided with the point of LDL size separation between the LDL subclass patterns A and B as an atherosclerotic risk.
Kondo
A
A
Department of Laboratory Medicine and Central Laboratory for Ultrastructure Research, Hamamatsu University School of Medicine, 3600 Handa-cho, Hamamatsu City 431-3192, Japan. akikondo@hama-med.ac.jp
Muranaka
Y
Y
Ohta
I
I
Notsu
K
K
Manabe
M
M
Kotani
K
K
Saito
K
K
Maekawa
M
M
Kanno
T
T
D000328:Adult; D000368:Aged; D003920:Diabetes Mellitus / Q000097:blood; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015228:Hypertriglyceridemia / Q000097:blood; D008077:Lipoproteins, LDL / Q000737:chemistry*; D008297:Male; D008315:Malondialdehyde / Q000737:chemistry*; D008875:Middle Aged; D010316:Particle Size; D014280:Triglycerides / Q000737:chemistry*
D008077:Lipoproteins, LDL; D014280:Triglycerides; D008315:Malondialdehyde