Energy and fat intake in obese and lean children at varying risk of obesity.

OBJECTIVE: This study compared lean children at high risk (HR) and low risk (LR) of obesity and obese children (OB) to assess the relationship between their energy (EI) and fat intake and adiposity. DESIGN: Cross-sectional study of energy and fat intake in children, using 7-day weighed intakes validated by doubly labelled water (DLW) energy expenditure. SUBJECTS: A total of 114 pre-pubertal children, 50 HR (mean+/-s.d., 6.7+/-0.6 y, 25.7+/-4.8 kg, 21.3+/-6.6% body fat), 50 LR (mean+/-s.d., 6.6+/-0.8 y, 23.6+/-3.7 kg, 18.9+/-5.7% body fat) and 14 OB (mean+/-s.d., 6.8+/-1.0 y, 37.7+/-5.3 kg, 34.8+/-5.6% body fat). MEASUREMENTS: Body fatness was measured using deuterium dilution, total energy expenditure (TEE) by DLW and dietary intake using 7-day weighed records. RESULTS: EI was 98% of TEE in LR children, 95% in HR children and 86% in OB children. Although EI was similar in each group (LR, 7.03+/-1.26 MJ/day; HR, 7.30+/-1.46 MJ/day; OB, 7.55+/-1.67 MJ/day), obese +/-4.6%; P<0.05). There was a significant linear trend towards increasing fat intake (percentage energy) with increasing risk of obesity (P<0.05). While HR children were heavier and fatter than LR children (P<0.05), their EI and fat intake were not significantly greater (HR, 73+/-17 g, 37.3+/-4.4%). Dietary fat intake (percentage energy) was weakly but significantly related to body fatness (r(2)=0.05, P=0.02) by step-wise regression. Since energy from fat was the only macronutrient that was a significant predictor of body fatness, results were therefore analysed using quartiles of fat intake (percentage energy) as cut-offs. When grouped in this way children with the lowest intakes were leaner than those with the highest intakes (19.5+/-7.5 vs 24.9+/-9.4% body fatness; P<0.05). There was a significant trend for increasing fatness as fat intake increased (P<0.05). CONCLUSION: Fat intake is related to body fatness in childhood.

Dietary fibre, exercise and serum lipids and lipoprotein cholesterols in 12 to 15 year olds.

Serum lipid and lipoprotein cholesterol levels track from childhood and are associated with risk of coronary heart disease. There is some evidence that these are influenced by dietary intake and exercise. Serum lipid and lipoprotein cholesterols were measured in a cohort of 119 British children aged 12-15 y who completed a dietary assessment and exercise questionnaire. The ratio of total- to high-density lipoprotein cholesterol fell with increasing fibre intake, but after adjustment for age, body mass index, sex and other dietary factors, this was not statistically significant. Children exercising at least once a day had significantly lower serum total cholesterol and low density lipoprotein cholesterol levels than those exercising less frequently, even after adjustment for the above factors and dietary fibre intake. No dietary factor was significantly associated with any lipid measure after adjustment for the above factors. The challenge is how to optimize exercise level in adolescent children.

Evaluation of a two-hour method for screening pathogens from stool specimens.

The 2-h stool-screening test (SST) (API System S.A., Montalieu-Vercieu, France) was used to screen 231 organisms yielding suspicious colonies on stool differential agars for potential pathogens. All 54 salmonellae yielded correct screens. Of 14 shigellas, 9 keyed as possible Shigella spp.-Yersinia enterocolitica-rare Salmonella spp. (SYS), and 5 (all Shigella sonnei) keyed as possible S. sonnei-Y. enterocolitica-Arizona spp. (SYA). Three Arizona strains were identified as probable Salmonella spp., two were identified as SYA, and one was identified as SYS. Seven Y. enterocolitica strains keyed as SYS, and two keyed as SYA; one strain was screened out as a nonpathogen. The two Aeromonas hydrophila strains keyed as SYA, and the two Plesiomonas shigelloides strains keyed as SYS. All 63 Proteus, Morganella, Providencia, and Pseudomonas aeruginosa strains were screened out as nonpathogens. Among 80 coliforms, 37 were screened as SYA, 32 were screened as SYS, and 11 were screened as nonpathogens. On the basis of the SST, 69/80 coliforms would have been tested further. However, only 1/88 potential pathogens would have been missed, and all Proteus, Morganella, Providencia, and P. aeruginosa strains would have been excluded. The capability of the SST (when combined with a rapid identification method) of providing same-day identification of potential stool pathogens must be weighed against its inability to effectively screen out coliforms. The cost of this method is equivalent to that of a three-tube conventional screening method. The suitability of the SST for individual laboratories must be predicated on the incidence of stool pathogens and commensals in the specific setting as well as on factors related to work flow, technologist acceptability, and turnaround time.

Challenge versus natural infection as an index or protection after influenza immunization.

The most important consideration in evaluating an immunization procedure is protection from infection. Protection provided by influenza vaccines can best be determined by large scale field trials and natural infection. However, these are difficult to control and epidemics cannot always be accurately predicted. On the other hand, representative artificial challenge studies can be controlled and are easier to perform. In the studies, reported protection achieved against artificial challenge is compared with protection effected in vaccinees during natural influenza epidemic. Protection rate against artificial challenge with influenza A was 96% when vaccine and challenge viruses were homotypic. When the vaccine strain and challenges virus were heterotypic, protection ranged from 70-100%. Protection rate from infection during a homotypic epidemic was, retrospectively, 95%; while 50-87% protection from influenza illness was achieved during a heterotypic epidemic. In all instances, vaccinees experienced mild, mostly afebrile upper respiratory symptoms, unlike controls who had moderate to severe symptoms, often with fever. Infecting virus was shed more often by unvaccinated controls. Although artificial challenge was performed in healthy young adults, epidemiological results indicate that similar protection can be achieved for children, the elderly or high risk. Thus statistically representative sampling of immunized and non-immunized controls and challenge can be used as a direct indication of vaccine efficacy against natural infection in all populations.