Validity of HOMA-IR as index of insulin resistance in obesity.
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Biomedical subjects
Publications and source records attributed to Maria Marcovecchio.
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Oxidant-antioxidant status was investigated in a group of severely obese prepubertal children in comparison with healthy subjects and in relation to a dietary restriction-weight loss program. All subjects underwent anthropometric measurements and determination of lipid profile, lag phase, malondialdehyde (MDA), and vitamin E. Compared with controls, obese children had a significantly higher body mass index (BMI) (28.97 +/- 2.42 vs. 16.03 +/- 1.88 kg/m2; P = 0.0002) and waist-to-hip ratio (WHR) (0.89 +/- 0.03 vs. 0.80 +/- 0.01; P = 0.0004); lag phase and vitamin E levels were significantly decreased [24.05 +/- 16.21 vs. 43.16 +/- 10 min (P = 0.004) and 21.12 +/- 14.96 vs. 35.54 +/- 13.62 micromol/liter (P = 0.02), respectively], whereas MDA was significantly increased (0.90 +/- 0.31 vs. 0.45 +/- 0.24 nmol/mg; P = 0.001). Both lag phase and MDA significantly correlated with BMI [respectively, r = -0.34 (P = 0.004) and r = 0.57 (P = 0.002)] and WHR [respectively, r = -0.63 (P = 0.0001) and r = 0.38 (P = 0.04)]. Oxidant status normalized after 6 months of dietary restriction [lag phase, 59.11 +/- 14.74 min (P = 0.002); MDA, 0.47 +/- 0.09 nmol/mg (P = 0.003)], which was associated with a reduction of BMI (27.34 +/- 1.87 kg/m2; P = 0.003), WHR (0.87 +/- 0.02; P = 0.001), and fat mass (34.49 +/- 2.68%; P = 0.008), but returned to baseline levels together with fatness indexes after another 6 months of free diet. Altered oxidant-antioxidant status is already present in prepubertal severely obese children and is reversible with a dietary restriction-weight loss program, which should be highly encouraged and maintained over time in this age group.
OBJECTIVE: Growth hormone deficiency (GHD) in adults is associated with increased oxidative stress determined by the underlying GH-IGF-1 axis alterations. Despite GHD being a common diagnosis in children with short stature, no data on the oxidant/antioxidant status are available in this age group. This study was designed to detect differences in oxidative stress parameters between prepubertal GH-deficient children and healthy controls. Furthermore, the effect of 12 months of conventional GH replacement (rGH) on oxidant-antioxidant status was evaluated in the GHD group only. PATIENTS: Ten (nine males and one female) prepubertal children (mean age 9.1 +/- 1.3 years) with GHD were recruited and matched for sex and age (9.2 +/- 1.9 years) with 20 healthy controls (18 males and two females). MEASUREMENTS: At study entry, lag phase, an index of susceptibility of low density lipoprotein (LDL) to in vitro oxidation, malondialdehyde (MDA) and vitamin E were measured in all subjects. These parameters were also evaluated in GH-deficient children after 12 months of rGH treatment. RESULTS: The lag phase was significantly decreased in GH-deficient children compared to healthy controls (15.50 +/- 7.4 vs. 43.00 +/- 9.2 min; P = 0.0007), while MDA was significantly increased (1.33 +/- 0.38 vs. 0.46 +/- 0.10 nmol/mg; P = 0.0006). Vitamin E levels were significantly decreased (22.44 +/- 9.57 vs. 35.38 +/- 16.49 micromol/l; P = 0.001). IGF-1 and IGFBP-3 correlated directly to lag phase (r = 0.48; P = 0.01; r = 0.63, P = 0.002, respectively) and to vitamin E (r = 0.59, P = 0.003; r = 0.58, P = 0.006, respectively). By contrast, IGF-1 and IGFBP-3 correlated indirectly to MDA (r = -0.47, P = 0.01; r =-0.65, P = 0.002, respectively). After 1 year of rGH therapy, lag phase (39.32 +/- 15.24 min; P = 0.005) and vitamin E (34.9 +/- 7.7 micromol/l; P = 0.005) increased significantly, while MDA decreased significantly (0.71 +/- 0.42 nmol/mg; P = 0.005), reaching normal levels. CONCLUSIONS: These data show that children with GHD have substantially increased oxidative stress parameters compared to healthy controls and demonstrate a normalization of these parameters after 1 year of rGH therapy.
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