J.G. Buchanan-Smith

Relationship between diet composition and body mass index in a group of Spanish adolescents

Tbe dietary patterns of sixty-four adolescents (tbirty-seven young men and twenty-seven young women) between 15 and 17 years of age were examined by analysis of food, energy and nutrient intakes, over a period of 5 d, including a Sunday. Adolescents were identified for inclusion in two study groups: (1) overweight and obese subjects (0) with a BMI (kg/mz) 2 75th percentile, and (2) subjects of normal weight (NW) with BMI < 75th percentile. The study was designed to investigate the differences between the energy and nutrient intakes of NW and 0 adolescents. No differences were found in energy intake between NW and 0 adolescents. However, 0 subjects derived a greater proportion of their energy from proteins (198 YO v 16.4 YO for NW subjects) and fats (45.4% v. 38.7 YO for NW subjects), and less from carbohydrates (34.6% v. 44.6% for NW subjects). Also, 0 subjects consumed significantly larger amounts of cholesterol. In order to prevent obesity and avoid the disorders associated with this condition, it appears necessary not only to regulate energy intake, but also to control the composition of the diet. Given that it is during infancy that feeding habits are developed, it is important to ensure that correct habits are acquired. Special attention should be given to improving the dietary habits of overweight and obese children and adolescents. Obesity: Adolescence: Dietary survey

A colorimetric method for the quantitation of uronic acids and a specific assay for galacturonic acid

A method of quantitating uronic acids and uronic acids from pectin in particular is described. The method uses carbazole in 80% sulfuric acid with borate ions added. The assay is carried out at 60 degrees C. This assay has some cross reactivity with aldose sugars and must be timed precisely. A further method that is specific for galacturonic acid is also described. This method uses concentrated sulfuric acid and carbazole only. Of the biological substances tested, only formaldehyde and glyceraldehyde showed a reactivity of more than 10% that of galacturonic acid on a weight to weight basis.

Effects upon glucose metabolism of feeding a low- or high-roughage diet at two levels of intake to sheep.

1. To determine the effect of diet and level of energy intake on glucose metabolism in sheep, four dietary treatments consisting of feeding a low-roughage (LR) and a high-roughage (HR) diet at each of two intake levels estimated to provide 586 and 1172 kJ (140 and 280 kcal) digestible energy (DE)/kg body-weight-0.75 per d were given to each of eight yearling rams in four different time periods each of 4 weeks duration. Both diets contained 140 g crude protein/kg using ground maize, mixed hay and soya-bean meal and were given in two meals/d. Estimated DE values of food were verified during the study and actual intakes of DE were within 9.5% of the estimated values. 2. To study glucose metabolism, a single intravenous injection of ]2-3H]glucose and subsequent withdrawal of nine venous blood samples with 3 h were made in each experiment. Two experiments were conducted on consecutive days for each sheep on each dietary treatment. 3. Coefficients of determination (r2) for linear regressions to measure the effect of time after a single injection of [2-3H)glucose on log specific radioactivity of plasma glucose were calculated for fifty-eight experiments. In fifty-six of the experiments, r2 values exceeding 0-95 were obtained. 4. Compared to the HR diet, the LR diet increased (P smaller than 0-05) the pool size and decreased (P smaller than 0-05) the half-life of glucose. At both intake levels, the LR diet increased (P smaller than 0-05) the plasma concentration and the entry rate of glucose compound to the HR diet but interaction (P smaller than 0-05) between diet and intake level was attributed to a greater difference obtained between diets at the higher compared to the lower level of food intake. Increasing the level of intake caused a greater (P smaller than 0-05) pool size and space, and a shorter (P smaller than 0-05) half-life of glucose. 5. It was concluded that substitution of roughage by concentrate in a ruminants diet may increase the rate of glucose entry during a short time period after eating.

EFFECTS OF IN VITRO ADDITION OF AMMONIA ON THE METABOLISM OF 15N-LABELLED AMINO ACIDS IN ISOLATED SHEEP HEPATOCYTES

Isolated hepatocytes prepared from sheep were used to determine the effects of added ammonia (as NH4Cl) on the flux of 15N from 15N-labelled amino acids to [14N15N]urea and [15N15N]urea. Hepatocyte suspensions were incubated with NH4Cl (0, 0.31, 0.63 and 1.25 mM) in the presence of L-[15N]alanine, L-[15N]methionine, L-[15N]leucine or L-[15N]phenylalanine (1.0 mM final concentration in the incubation media). Following 1.5 h incubation, addition of NH4Cl increased total urea and unlabelled (14N14N) urea production in all incubations (P < 0.001). Adding NH4Cl did not affect 15N isotopic enrichment of [14N15N]urea (P = 0.705) and [15N15N]urea (P = 0.204), or production of [14N15N]urea (P = 0.279) and [15N15N]urea (P = 0.708) in isolated hepatocytes incubated with [15N]alanine. Addition of NH4Cl increased [14N15N]urea production in incubations containing [15N]methionine (quadratic effect, P = 0.019), but had no effect in incubations containing [15N]leucine (P = 0.107) or [15N]phenylalanine (P = 0.135). There w...

The role of gut tissue in the energy metabolism of growing lambs fed forage or concentrate diets.

The role of the gastrointestinal tract (GIT) in explaining the less efficient utilization of metabolizable energy (ME) in growing lambs fed forage rather than concentrate-based diets was investigated by feeding forage (legume-grass silage) and concentrate (whole shelled maize) diets, at isoenergetic intakes (ME basis), using five groups of lambs. One group of seven lambs was an initial slaughter group and of the two groups (eight lambs per group) fed each diet, one group was fed for 8 weeks, whereas the other group was fed for 16 weeks. All lambs were slaughtered between 18.5 and 20 h following their last meal. Retained energy (as a percentage of ME intake) was higher (concentrate-fed 28, forage-fed 17; P<0.001) for the concentrate-fed animals. Weight-specific mucosal O2 uptake (ml/g DM per h), measured in vitro, was 37 % higher for the forestomach (reticulum, rumen and omasum) and small intestine (jejunum) than for the abomasum and large intestine (caecum and colon), but there was no evidence for a diet effect (except colon; forage-fed 5.3, concentrate-fed 4.2; P=0.036). Total GIT heat loss was estimated as 14 (forage-fed) and 18 (concentrate-fed) % of the whole-body heat loss. Although the GIT did not contribute to increased thermogenesis in the forage-fed lambs in the present study, greater relative contribution of GIT tissue to whole-body mass, i.e. GIT as a percentage of empty-body weight(forage 7.6, concentrate 6.6; P<0.001) in the forage-fed animals supports a role for the GIT in contributing to higher thermogenesis observed in ruminants fed forage as opposed to concentrate diets.