Objective: To analyse the association between waist-to-height ratio (WtHR) and body fat and to develop predictive adiposity equations that will simplify the diagnosis of obesity in the paediatric age group. Design: Cross-sectional study conducted in Spain during 2007 and 2008. Anthropometric dimensions were taken according to the International Biology Program. The children were classified as underweight, normal weight, overweight or obese according to national standards of percentage body fat (%BF). WtHR differences among nutritional status categories were evaluated using ANOVA. Correlation analysis and regression analysis were carried out using WtHR as a predictor variable for %BF. A t test was applied to the results obtained by the regression model and by the Siri equation. The degree of agreement between both methods was evaluated by estimating the intra-class correlation coefficient. Setting: Elementary and secondary schools in Madrid (Spain). Subjects: Girls (n 1158) and boys (n 1161) from 6 to 14 years old. Results: WtHR differed significantly (P , 0?001) depending on nutritional status category. This index was correlated (P , 0?001) with all adiposity indicators. The mean %BF values estimated by the regression model (boys: %BF 5 106?50 3 WtHR -28?36; girls: %BF 5 89?73 3 WtHR -15?40) did not differ from those obtained by the Siri equation. The intra-class correlation coefficient (0?85 in boys, 0?79 in girls) showed a high degree of concordance between both methods. Conclusions: WtHR proved to be an effective method for predicting relative adiposity in 6-14-year-olds. The developed equations can help to simplify the diagnosis of obesity in schoolchildren.

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Modifications in the enzyme activity of lysozyme, a protein implied in the defence barrier of the organism, can be a good biomarker of alterations in the immune system as a result of exposure to toxic metal, such as lead. The aim of this work was to evaluate the effect of a 200 ppm dose of lead on lysozyme activity in blood, kidney, and lung, and also on tissue structure. Previously, the effect of lead acetate on lysozyme activity in vitro was determined; the in vitro results indicated that lead produced a decrease in enzyme activity. The activity loss was 16 % at 200 ppm of lead. Lead acetate was administered to Wistar rats by oral and intraperitoneal injections. An increase in lysozyme activity was observed in blood when lead was administered by introperitoneal route and in kidney by the oral route. The possible immunostimulation in kidney was discarded because of the structural alterations observed in the tissue. In lung, the decrease in specific lysozyme activity, for both routes of lead exposure, seems to indicate immunosupression, which was in accordance with the structural alterations observed in this tissue.

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