Paraoxonase activity in high-density lipoproteins: a comparison between healthy and obese females.

Paraoxonase, an enzyme associated with high-density lipoprotein (HDL-PON), exerts a protective effect against oxidative damage of circulating cells and lipoproteins, modulates the susceptibility of HDL to atherogenic modifications such as glycation and homocysteinylation, and even exerts an antiinflammatory role. The aim of the present study was to investigate the relationship between lipoprotein oxidative stress and the activity of HDL-PON in healthy and obese subjects. Therefore, the activity of HDL-PON and the levels of lipid hydroperoxides in HDL and low-density lipoprotein (LDL) isolated from plasma of obese females (n = 12) and age-sex-matched controls (n = 31) were compared. Our results demonstrated for the first time that the activity of HDL-PON in obese subjects was significantly lower compared with that in controls (P < 0.001). Moreover, our results showed a significant increase in the levels of lipid hydroperoxides in HDL and LDL isolated from obese subjects (P < 0.001). The negative correlations established between HDL-PON activity and the levels of lipid hydroperoxides associated with HDL and LDL confirm the relationship between paraoxonase activity and lipid peroxidation of lipoproteins. Plasma levels of leptin correlated negatively with HDL-PON activity and positively with levels of lipid hydroperoxides in HDL and LDL of obese subjects, suggesting a relationship between leptin and oxidative damage of lipoproteins. In conclusion, our study demonstrated that the increase in oxidative stress in LDL and HDL of obese subjects is associated with a decrease in HDL-PON activity. The lower paraoxonase activity and the compositional changes in HDL and LDL could contribute to the greater risk of cardiovascular disease associated with obesity.

Body composition in advanced-stage Parkinson's disease.

Little is known about body composition in Parkinson's disease (PD). We studied 35 patients (20 male, 15 female subjects; mean age 69.7+/-5.8 years) with advanced PD by anthropometry, dual-energy X-ray absorptiometry (DEXA), and serum 25-OH vitamin D measurement. Over 70% of patients had a disease duration of more than 4 years; all were on L-dopa treatment. Low levels of serum 25-OH vitamin D were present in 41% of the patients. The mean body mass index (BMI) was 25.3+/-4.3 kg/m(2) (range 17.1-37.3). Mid-arm muscle circumference was below the 10th percentile in 23%. For whole-body mean (+/-SD) bone mineral density, the T score was below -1 SD in 35% of patients, and the Z score was below -1 SD in 24%. Percent fat mass measured with DEXA was 30.6+/-11.4% (range 10.1-45.5) in the overall sample; it was 21.1+/-8.8% (range 10.1-30.4) in male subjects and 38.1+/-9.2% (range 25.8-45.5) in female subjects. We conclude that advanced-stage PD may show excess adiposity coexisting with depletion of lean body mass (sarcopenic obesity), in addition to decreased whole-body bone mineral density associated with low serum 25-OH vitamin D. A low level of physical activity and inadequate exposure to sunlight are likely to be among the putative causes.

Effect of human Apo AIV against lipid peroxidation of very low density lipoproteins.

Recent studies have demonstrated that Apo AIV exerts a protective effect against atherosclerosis. Moreover, Qin et al. (Am. J. Physiol. 274 (1998) H1836) have demonstrated that Apo AIV, isolated from rat plasma, exerts an inhibitory effect against Cu(2+)-induced lipid peroxidation of intestinal lymph and LDL. The aim of the study was to investigate whether human Apo AIV exerts a protective effect against Cu(2+)-induced lipid peroxidation. Our results demonstrated that human Apo AIV exerted an inhibitory effect against Cu(2+) and AAPH induced lipid peroxidation of VLDL, as shown by the lower increase in the levels of TBARS and conjugated dienes in lipoproteins preincubated with Apo AIV. In addition, the tryptophan (Trp) and probe 2-(dimethylamino)-6-lauroylnaphthalene (Laurdan) fluorescence studies demonstrated that the modifications of spectral properties in both lipoproteins preincubated with Apo AIV were lower with respect to ox-lipoproteins, suggesting that Apo AIV prevents the modification of physico-chemical properties due to peroxidation.

Morphological study of the capsular organization around tissue expanders coated with N-carboxybutyl chitosan.

Expanders coated with N-carboxybutyl chitosan were inserted into surgical wounds in the dorsal skin of rabbits and the formation of capsular tissue was studied by scanning electron microscopy and transmission electron microscopy. N-carboxybutyl chitosan, in the course of the capsular organization, favours and potentiates the correct proliferation and organization of the tissue, rather than sustaining reactive processes leading to scar formation. N-carboxybutyl chitosan stimulates physiologically the tissue repair process and favours angiogenesis, whilst depressing fibrogenesis to a certain extent. Applications are envisaged in the treatment of wounds and in plastic surgery.