Dietary determinants of serum paraoxonase activity in healthy humans.

The associations between habitual diet and a variety of markers of lipid peroxidation or oxidative stress in a group of 95 healthy comparatively young Finnish volunteers (24 male and 71 females) were investigated. The habitual diet of the subjects was evaluated with a 3-day food record. The following biochemical parameters related to lipid peroxidation or oxidative stress were measured: lagtime of Cu2+ induced LDL oxidation in vitro, lipid hydroperoxides and Schiff bases produced during the LDL oxidation test, malondialdehyde measured as thiobarbituric acid-reactive substances from native LDL and Cu2+ oxidized LDL, serum paraoxonase (PON) activity. Serum PON activity showed most constantly associations with habitual diet. PON activity correlated negatively (r=-0.31 to -0.37) with intake of vegetables, total and water-soluble fiber, as well as intake of beta-carotene. Highly significant difference (P=0.005) in PON activity between lowest (<135 g/day) and highest (>256 g/day) vegetable intake quartiles was found. Malondialdehyde levels showed conflicting associations with diet. The results suggest that the significantly lower PON activity associated with high vegetable intake needs to be studied further.

Low HDL-C predicts the onset of transplant vasculopathy in pediatric cardiac recipients on pravastatin therapy.

The levels and protein/lipid compositions of major lipoprotein particles of 19 pediatric cardiac transplant recipients (4-18 yr of age) were studied in this prospective, open clinical follow-up study before and at one yr of pravastatin therapy (10 mg/day). The recipients were grouped into those with (n = 6; group A) and those without (n = 13; group B) angiographically detectable vasculopathy. Twenty-one pediatric non-transplant controls were studied at baseline. At baseline, the group A recipients had 29% lower HDL-C concentrations (p = 0.031) and 29% higher apoB-100/apoA-I ratios (p = 0.034) than the group B recipients. At one yr of pravastatin, the respective figures were 29% (p = 0.013) and 33% (p = 0.005). Compared with the healthy pediatric controls, the transplant recipients had significantly higher serum TG before pravastatin [median (range): 1.3 mmol/L (0.6-3.2) vs. 0.7 mmol/L (0.3-2.4), p = 0.0002] and at one yr [1.3 mmol/L (0.5-3.5) vs. 0.7 mmol/L (0.3-2.4), p = 0.0004]. The baseline apoB-100/apoA1 ratios of the recipients were 33% higher (p = 0.005). In conclusion, low HDL-C and high apoB-100/apoA-I ratio were associated with angiographically detectable vasculopathy. Even though pravastatin effectively lowered the TC and LDL-C and improved compositional properties of LDL and HDL(2) particles, it failed to normalize the elevated TG and, in some patients, to prevent the progression of transplant vasculopathy.