W. Andrew Coward

Association of physical activity with body-composition indexes in children aged 6–8 y at varied risk of obesity

BACKGROUND Physical inactivity increases the risk of obesity, but the relations between reported levels of physical activity (PA) and measures of body fatness (BF) in children are remarkably inconsistent. OBJECTIVE We examined the relation between objective measures of PA and body-composition indexes in nonobese children. DESIGN A cross-sectional study was conducted in 100 children aged 6-8 y who were recruited according to their risk of future obesity: high-risk children had >/=1 obese parent [body mass index (BMI; in kg/m(2)): >30] and low-risk children had 2 nonobese biological parents (BMI: <30). Free-living activity energy expenditure (AEE) and PA level were calculated from 7-d doubly labeled water measurements, time spent in light-intensity activity was assessed by heart rate monitoring, and body composition was determined from isotopic dilution. To adjust for body size, fat mass and fat-free mass were normalized for height and expressed as fat mass index (FMI) and lean mass index (LMI), respectively. RESULTS High-risk children had significantly higher BMI, LMI, and FMI than did low-risk children, but no group differences in PA were found. AEE and PA level were positively associated with LMI and, after adjustment for sex and fat-free mass, negatively associated with FMI but not with BMI. Boys who spent more than the median time in light-intensity activities had significantly higher FMI than did less sedentary boys. This difference was not observed in girls. CONCLUSIONS AEE and PA level were negatively associated with BF in nonobese children. Accurate measures of body composition are essential to appropriate assessment of relations between PA and obesity risk.

Validation of a quantitative magnetic resonance method for measuring human body composition.

Objective: To evaluate a novel quantitative magnetic resonance (QMR) methodology (EchoMRI‐AH, Echo Medical Systems) for measurement of whole‐body fat and lean mass in humans.

Specific Immunoglobulin A Antibodies in Maternal Milk and Delayed Helicobacter pylori Colonization in Gambian Infants

BACKGROUND Immunoglobulin A (IgA) in maternal milk may protect Gambian infants from early Helicobacter pylori colonization. This study sought evidence that this protection could be due to specific IgA antibodies. METHODS Sixty-five infants were screened from 12 weeks of age with [13C]-urea breath tests. Antibodies in maternal milk were measured to determine total IgA content and to detect specific IgA antibodies against crude whole-cell and recombinant H. pylori urease antigen preparations. RESULTS Ten children (15%) had no evidence of early H. pylori colonization, 10 (15%) had early H. pylori colonization, and 43 (66%) had mixed results. Levels of maternal circulating specific immunoglobulin G, total milk IgA, and IgA directed against crude whole-cell H. pylori antigen preparation were not significantly associated with the rate of infant H. pylori colonization. However, mothers of infants with no evidence of early colonization produced significantly higher levels of anti-recombinant urease IgA antibodies in milk than did control mothers, particularly at 8, 16, and 20 weeks postpartum (P<.01). CONCLUSIONS These observations support the hypothesis that antibodies in mothers milk directed against H. pylori urease can protect against colonization in human infancy.

Placental Acquisition of Maternal Specific IgG and Helicobacter pylori Colonization in Infancy

Background.  Colonization with Helicobacter pylori generally occurs in infancy, and the microorganism is often acquired from close family members. Rate of infant colonization may be affected by maternal immune status.