Body mass index, waist circumference and waist–hip ratio and serum levels of IGF-I and IGFBP-3 in European women

OBJECTIVE

To examine the relationship between body mass index (BMI) and waist-hip ratio (WHR) with serum levels of insulin-like growth factor-I (IGF-I), and its binding protein (IGFBP)-3.

DESIGN

Cross-sectional study on 2139 women participating in a case-control study on breast cancer and endogenous hormones. Data on lifestyle and reproductive factors were collected by means of questionnaires. Body height, weight, waist and hip circumferences were measured. Serum levels of IGF-I and insulin-like binding protein (IGFBP)-3 were measured by enzyme-linked immunosorbent assays. Adjusted mean levels of IGF-I and IGFBP-3 across quintiles of BMI, waist circumference, and WHR were calculated by linear regression. Results were adjusted for potential confounders associated with IGF-I and IGFBP-3.

RESULTS

Adjusted mean serum IGF-I values were lower in women with BMI<22.5 kg/m(2) or BMI>29.2 kg/m(2) compared to women with BMI within this range (P(heterogeneity)<0.0001, P(trend)=0.35). Insulin-like growth factor-I was not related to WHR after adjustment for BMI. IGF-binding protein-3 was linearly positively related to waist and WHR after mutual adjustment. The molar ratio IGF-I/IGFBP-3 had a non-linear relation with BMI and a linear inverse relationship with WHR (P (trend)=0.005).

CONCLUSIONS

Our data confirm the nonlinear relationship of circulating IGF-I to total adiposity in women. Serum IGFBP-3 was positively related to central adiposity. These suggest that bioavailable IGF-I levels could be lower in obese compared to non-obese women and inversely related to central adiposity.

[In vitro control of Sclerotinia sclerotiorum and Gaeumannomyces graminis by bacteria of the fluorescent Pseudomonas group]

Thirty six fluorescent Pseudomonas isolates were obtained from the rhizosphere of sunflower plants. By antibiosis tests, the six more efficient strains in Sclerotinia sclerotiorum growth inhibition, were selected. Simultaneously, twenty three fluorescent Pseudomonas isolates were recuperated from the rhizosphere of wheat plants and the five most efficient strains in growth inhibition of the fungi Gaeumannomyces graminis were selected. The strains selected from the rhizosphere of sunflower plants had no antagonistic effect on G. graminis and the bacteria isolated from the wheat rhizosphere showed no fungistatic activity on S. sclerotiorum. These results suggest the existence of a certain degree of plant bacteria pathogenic specificity. Among the selected bacteria, the strain FF5 of P. fluorescens originated the major inhibiting halo in vitro against S. sclerotiorum (Figure 1). In liquid culture medium this bacterium produces an antifungal substance that promotes lysis of fungi mycelium (Figure 2) and inhibition of ascospore germination and is not inhibited by the presence of Fe+3 in the culture medium (Table 1). Its synthesis is not associated with the production of fluorescein. Its action is not enzymatic because it is a substance of low molecular weight (< 2000), resistant to autoclave sterilization and photo-stable. The amount of NH4+ and the high pH values produced by the FF5 strain in the liquid culture medium (Table 2) are not responsible for the antifungalal action.