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    Insulin-like growth factor-1 (IGF-1) and dehydroepiandrosterone sulphate in obese women

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    Severe obesity is known to reduce either dehydroepiandrosterone circulating levels or growth hormone (GH) and insulin-like growth factor-1 (IGF-1) secretion. The present study was undertaken to evaluate the possibility of a relationship between the circulating levels of IGF-1 and those of dehydroepiandrosterone sulphate (DHEAS) in 25 fertile obese women. A logarithmic transformation of the values of non-normally distributed variables was performed before statistical analysis. We found a significant positive correlation between DHEAS and IGF-1 (r = 0.615, P < 0.01). In addition, stepwise multiple regression analysis showed that IGF-1 maintained a strong positive relationship with DHEAS (P < 0.01) when adjusted for other variables such as age, body mass index (BMI), waist:hip ratio (WHR) and insulin levels (adjusted R2 = 0.373; P < 0.01). These findings suggest that IGF-1 may independently influence the DHEAS circulating levels. ADG (5 alpha-androstan-3 alpha, 17 beta-diol-glucuronide) was also positively correlated to IGF-1 (r = 0.436, P < 0.05). However, when ADG concentrations were adjusted for DHEAS levels, this metabolite was not significantly correlated with IGF-1, thus excluding a direct influence of IGF-1 on the 5-alpha-reductase activity. Therefore, although our data represent only a preliminary study, they seem to suggest a possible influence of IGF-1 on circulating levels of DHEAS in obese women

    Reduced effectiveness of atrial natriuretic factor in pre-menopausal obese women

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    It is well-known that the prevalence of hypertension progressively increases with body weight. Since the major physiological activities of atrial natriuretic factor (ANF) are its natriuretic, diuretic and vasodilatory effects, the aim of the present study was to investigate the ANF basal plasma levels and platelet receptor number in 15 young normotensive obese (O) and 12 age-matched normal weight healthy (C) women. ANF effectiveness was also studied in eight of the obese and seven of the control women, after an intravenous bolus of the hormone (human ANF (99-126): 0.5 mg/kg body weight). Results are expressed as means+s.d. Basal ANF plasma levels were similar between obese (18.2 +/- 9.7 pg/ml) and control women (12.3 +/- 7.7 pg/ml), whereas obese patients showed an increase density of platelet ANF-binding sites (clearance receptors) (C: 28.7 +/- 33.5 fmol/10(9) cells; O: 39.6 +/- 4.6 fmol/10(9) cells; P < 0.001), without apparent differences in receptor affinity (Kd) (C: 6.0 +/- 3.0 pM; O: 7.0 +/- 2.0 pM). The biological response to ANF, evaluated by changes of mean blood pressure levels (C: 5 +/- 1 mmHg; O: 1 +/- 1 mmHg; P < 0.001) and the percentage increase of diuresis (C: 159 +/- 52%; O: 81 +/- 62%; P < 0.01) and natriuresis (C: 205 +/- 129%; O: 99 +/- 41%; P < 0.05) was significantly reduced in obese patients. The percentage increase in sodium excretion was inversely related to the basal insulin concentrations in the obese group (r = 0.64, P < 0.05)
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