Fecal characteristics in healthy young adults consuming defined liquid diets or a free-choice diet

Fat and nitrogen absorption and fecal characteristics were studied in 10 healthy, young adults who ingested a free-choice diet for 12 days and then isocaloric amounts of one of two nutritionally complete liquid defined formula diets during a succeeding 12-day period. Apparent fat absorption was 98 to 99% of intake with both defined formula diets and 95% of intake on the free-choice diet. Nitrogen digestibility was determined during the liquid diet period, and averaged 95 to 98% of intake. There were no statistically significant differences between the liquid diets and the free-choice diets with respect to fecal wet or dry weight, transit time, or stool frequency. Individual stool weights averaged 83 to 96 g on the free-choice or liquid formula diets and were comparable to other values reported in the literature. These results support the theory that a critical volume of feces must accumulate in the colon before defecation occurs, regardless of diet composition.

Low serum reverse T3 concentration in burned children: its relationship to nutritional state

The correlation between protein turnover and serum thyroid hormone levels was studied in 10 children, ages 1 to 16 years subsequent to severe burn injuries. In contrast to published studies that have shown depression of triiodothyronine (T3) and elevations of reverse T3 (rT3) in stressed patients, no change was found in the mean level of T3 and a 69% decrease in rT3 compared to healthy controls of similar age. Whole body rates of protein synthesis and breakdown were determined using a [15N]glycine turnover technique. The difference between synthesis and breakdown was negatively correlated with the ratio, rT3/T3 in serum. Thus, in burned children, a decrease in N balance was associated with a rise in rT3/T3 which is qualitatively similar to that observed in fasted individuals or in stressed patients who may be semistarved.

Increased rates of whole body protein synthesis and breakdown in children recovering from burns

The rates of whole body protein synthesis and breakdown were determined, with the aid of a constant administration of [15N]glycine, during recovery in 11 acutely burned children, involving a total of 24 studies. Eleven studies were also conducted in seven healthy children before and after reconstructive surgery. Rates of whole body protein synthesis and breakdown, expressed as g protein/kg body weight/day, were significantly (p less than 0.05) and positiviely correlated with per cent body surface area total burn, per cent third-degree burn, and per cent open wound. These rates (synthesis, 7.1 +/- 2.1 g protein/kg/day; breakdown, 6.3 +/- 1.8 g protein/kg/day) were 80 to 100% greater (p less than 0.05) in patients with total burns greater than or equal to 60%, as compared to patients with less than 25% total burns or to the surgical patients. Because of the high energy cost of protein synthesis, it is proposed that an increased whole body protein turnover is partly responsible for the reported elevations in rates of heat production occurring in patients recovering from thermal injury.

Whole body protein synthesis in relation to basal energy expenditure in healthy children and in children recovering from burn injury

Dynamic aspects of whole body nitrogen metabolism in children recovering from burn injury have been examined in relation to basal metabolic rate (BMR). A continuous administration of [15N]glycine was used to estimate the rates of whole body protein synthesis (S) and breakdown (C) in five acutely burned children (ages 5-16 years) and in nine healthy subjects (ages 9-18 years). S (grams of protein per kg body wt per day) and BMR were significantly correlated (r = +0.73; P less than 0.01). There was no significant correlation of C with BMR. The ratio of S (grams of protein per day) to BMR (kilocalories per day) was the same in burned and healthy children; the mean value for all children was 0.10 +/- 0.03 g protein synthesis/basal kcal. Calorie intake and S were significantly correlated (r = +0.70; P less than 0.01). There were significant correlations between BMR and percentage of total body surface area burned (r = +0.66; P less than 0.01), and BMR and age (r = -0.57; P less than 0.05). Age did not correlate significantly with percent of total body surface burned.

Whole-body protein synthesis and breakdown rates in children before and after reconstructive surgery of the skin

The effects of minor surgery on dynamic aspects of whole-body nitrogen metabolism were explored in healthy children aged 4--15 yr. A continuous administration of 15N-glycine was used to estimate rates of whole-body protein synthesis and breakdown both before reconstructive surgery of the skin and 5 days afterward. Mean preoperative values for protein synthesis and protein breakdown were 3.9 and 3.4 g protein/kg body weight/day, respectively. Protein synthesis decreased by 15% (p less than 0.05) postoperatively, but body weight, intake of protein and calories, nitrogen balance, and protein breakdown did not differ significantly between the two periods. Protein synthetic rate correlated (p less than 0.05) with protein (r = +0.75) and calorie (r = +0.58) intake. These results indicate that minor surgery causes a small decrease in the rate of whole-body protein synthesis even though calorie and nitrogen balance are maintained.