Platelet-Activating Factor Acetylhydrolase Concentration in Children With Abdominal Obesity

Abstract

In human obesity, increased oxidant stress is an important factor in the development of atherosclerosis. 1 Oxidation of the lipid components of low-density lipoprotein (LDL) is causative, because oxidized LDL contributes to many of the stages of progression of atherosclerosis. In particular, small dense LDL particle, which is frequently associated with abdominal obesity, 2 is susceptible to oxidative modulation. Even in obese children, oxidative stress including oxidized LDL formation is increased. 3,4 Platelet activating factor acetylhydrolase (PAF-AH) is a Ca 2ϩ -independent phospholipase A 2 that catalyzes the conversion of platelet activating factor (PAF) to lyso-PAF. Another physiological function of plasma PAF-AH is to degrade oxidized phospholipids, which are formed during the oxidative modification of lipoproteins. Therefore, PAF-AH may play a significant role in atherogenesis as an antioxidant. We measured PAF-AH concentration in children with abdominal obesity and investigated its relationship with anthropometric and metabolic parameters.The subjects were 17 obese children (10 male, 7 female) aged 11.9Ϯ0.7 years (meanϮSE) who presented to our outpatient clinic with obesity. Obesity was defined as a relative body weight Ͼ120%, which was calculated according to the standard weight obtained for sex, age, and height on the basis of data from the Ministry of Education, Science, Sports, and Culture. 5 Skinfolds were measured at triceps and subscapular regions using a skinfold caliper. Waist circumference was measured at the umbilical level. Blood samples were collected in the morning after a 12-hour fast. Serum total cholesterol (TC), high-density lipoprotein cholesterol (HDLC), and triglyceride (TG) levels were determined by standard enzymatic methods. LDL cholesterol (LDLC) was calculated by means of the Friedewald formula. LDL peak particle diameter was determined using gel electrophoresis according to our previous report. 2 Apolipoprotein B (ApoB) concentration was measured by tubidimetric immunoassay. Plasma insulin and glucose concentrations were determined and homeostasis model of assessment ratio (HOMA-R) was obtained using Matthews formula as an index of insulin resistance. 6 Plasma PAF-AH concentration was measured by ELISA. 7 All children were free from disease except for hyperlipidemia and obesity. Informed consent was obtained from each child and the parents.The prevalence of hypercholesterolemia (Ͼ220 mg/dL), hypertriglyceridemia (Ͼ120 mg/dL), and low HDLC level (Ͻ40 mg/dL) was 23.5%, 64.7%, and 1.8%, respectively. We found a child with glucose intolerance (Ͼ110 mg/dL). HOMA-R was 5.4Ϯ1.4. All children had abdominal obesity, which was defined as waist/height ratio over 0.5. PAF-AH concentration was 1.5Ϯ0.1 g/mL, with no significant sex difference. In simple regression analyses, PAF-AH concentration correlated positively with relative weight (r 2 ϭ0.272, Pϭ0.0316), waist/height ratio (r 2 ϭ0.296, Pϭ0.0240), subscapular/ triceps ratio (r 2 ϭ0.312, Pϭ0.0304), and LDLC level (r 2 ϭ0.248, Pϭ0.0421),...

Plasma Lipoprotein-associated Phospholipase A2 in Patients with Metabolic Syndrome and Carotid Atherosclerosis

“…Additionally, we found Lp-PLA 2 correlated with glucose and HbA1c weakly but significantly only in simple regression. Our findings were in accordance with the previous studies, in which Lp-PLA 2 correlated with abdominal adiposity [27,28] but differed from the results of Noto et al [25] and Rana et al [29], who found that plasma Lp-PLA 2 activity did not appear to be associated with waist circumference. It was possible that obesity was associated with decreases in local and peripheral insulin resistance [30].…”

Elevated circulating levels of lipoprotein-associated phospholipase A2 in obese children

“…This correlation reinforces the results of previous studies in children showing positive correlations of Lp-PLA2 with LDL-C [16,28] and can be easily explained by the fact that Lp-PLA2 is transported in the circulation bound mainly with LDL molecules, while < 20% of Lp-PLA2 is associated with HDL [29,30] .…”

Influence of obesity and cardiometabolic makers on lipoprotein-associated phospholipase A2 (Lp-PLA2) activity in adolescents: the healthy young cross-sectional study

“…At the moment, there are only four studies evaluating Lp-PLA 2 in children and adolescents. First, Okada et al [42] showed that the Lp-PLA 2 concentration of 17 obese children (11.9 ± 0.7 years old) was positively correlated with weight, waist/height ratio, subscapular/triceps ratio and LDL-C level. Castro et al [43] compared diabetic young adults and adolescents (24.9 ± 7.8 years old) with controls (24.3 ± 9.6 years old), observing higher Lp-PLA 2 activity and elevated susceptibility for oxidized LDL in diabetic patients.…”