Metabolic Alterations Following Thermal Burns. I. Nitrogen Balance in Experimental Burns1

Abstract

Several investigators (1 to 4) have shown that a negative nitrogen balance exists following a burn. It was suggested that the prevention or alleviation of this loss of nitrogen might promote healing and improve the prognosis of the severely burned patient. Since, however, it is difficult to evaluate the significance of nitrogen balance studies in patients because of the marked variation in their age, their nutritional status previous to burning, and the depth and severity of their injury, it seemed advisable to carry out nitrogen balance studies in animals under controlled conditions. METHODS AND MATERIALSAdult female mongrel dogs were selected for the study. They were fed 10 or 11 grams per kilogram of body weight of the following mixture in parts per hundred: casein 37.4, dextrose 26.4, Crisco 22.2, salt mixture (U.S.P. Salt Mixture No. 1) 3.5, dried yeast 6.8, bone ash 2.7, and cod liver oil 1.0. The amount of food consumed daily by each animal was weighed, and samples of each batch of food were analyzed for nitrogen content. After the dogs had consumed this diet for a preliminary period of ten days to two weeks, they were placed in metabolism cages. Urine was collected under toluene and a daily aliquot removed and pooled for a 5-day period. At the beginning of the study, and at the end of each 5-day period, the bladder was catheterized to insure full collection. Feces, marked with carmine, were preserved with an acid-alcohol solution, dried on the steam bath and ground to a powder.The nitrogen balance and body weight were followed for three 5-day periods to insure nitrogen equilibrium or a slightly positive balance and the maintenance of relatively constant weight. The animals were then burned under anesthesia (intravenous nembutal). Hot irons with a uniform surface area (12.57 cm.) were employed so that an estimate of the surface area burned could be calculated.

Metabolic Alterations Following Thermal Burns. VII. Effect of Force-Feeding, Methionine, and Testosterone Propionate on Nitrogen Balance in Experimental Burns

“…scribed (1). Four animals were used for the force-feeding experiments and 2 each for the testosterone and methionine studies.…”

Metabolic Alterations Following Thermal Burns. Vii. Effect of Force-Feeding, Methionine, and Testosterone Propionate on Nitrogen Balance in Experimental Burns 1

“…Previous work (1) demonstrated that following an experimental burn animals were in negative nitrogen balance on a caloric and protein intake that had been sufficient to maintain nitrogen equilibrium during several control periods prior to burning. The total circulating plasma proteins in these animals remained the same, or in some instances increased slightly, while the concentration and total amount of albumin decreased (2).…”

“…By means of increasing the nitrogen intake in a group of patients, the negative nitrogen balance was prevented or diminished, but in most instances when the very high diets were given early, they were poorly tolerated (8). In scribed (1). Four animals were used for the force-feeding experiments and 2 each for the testosterone and methionine studies.…”