Total body water in malnutrition: the possible role of energy intake

Total body water (TBW) was measured using tritiated water in sixty-five children. The measurements were distributed throughout rehabilitation in order to define the effect of changing energy intakes. Oedematous children had a high TBW which decreased to the normal range during loss of oedema providing they were not receiving more than maintenance amounts of energy during this period. Marasmic children who had not received greater than maintenance amounts of energy had a normal TBW. Treatment with a high-energy diet was associated with an initial increase in TBW. The possible mechanisms for this phenomenon are discussed.(AU)

Muscle mass and composition in malnourished infants and children and changes seen after recovery

A method of measuring muscle mass in children with [15N]creatinine has been used to study changes in muscle after recovery from protein-energy malnutrition. Creatinine pool size, muscle mass, total muscle cell number, muscle cell size, and total body water have been measured in seven malnourished and eight recovered children. After recovery there was a significant reduction in the muscle concentration (micrograms mg[-1] wet wt muscle) of creatine (4.21 to 3.12), and a trend towards reduction in noncollagen protein (155 to 136) and DNA (2.13 to 1.34). The fractional turnover rate of creatine did not change but the creatine pool size increased significantly (4.2 to 5.6 g). Average muscle mass almost doubled (1.00 to 1.91 kg) and made up a greater percentage of body weight (16 to 22 percent). When muscle mass was expressed as a percentage of the expected muscle mass for a normal child of the same height the increase with recovery was from 49 percent to 92 percent. Total muscle noncollagen protein (NCP) increased after recovery (153 to 265 g) and accounted for a greater percentage of total body solids (6.6 to 8.5 percent). The average total muscle DNA was 2.049 g in the malnourished and 2.380 g in the recovered children and the ratio of NCP:DNA increased from 92 to 110 on recovery. Total body water as a percentage of body weight was not significantly different after recovery. Values for muscle mass in recovered children were similar to those reported for normal children of the same weight, height, and age. (Summary)

The energy cost of repleting tissue deficits during recovery from protein-energy malnutrition

Five children with protein-energy malnutrition were treated with a high calorie, high protein diet and the energy cost of growth in body weight and muscle mass were calculated. Energy expenditures correlated statistically with increases in muscle mass, estimated by [15N] creatine kinetics, but not with gains in body weight.(AU)

The measurement of muscle mass in children using [15N] creatinine

In eight infants and children who had recovered from protein-energy malnutrition (PEM), muscle mass was estimated by measuring creatine turnover by an isotope dilution technique using [15N] creatine, creatine concentration, and urinary creatinine output. Creatine turnover varied from 1.5 to 2.6 percent of the muscle creatine pool per day and muscle creatine concentration ranged from 1.7 to 3.9æg/æg muscle DNA. Muscle mass was between 15 percent and 37percent of total body weight. The results indicate that daily creatinine output is not reliable indicator of muscle mass in children who have recently recovered from severe PEM.(AU)

The catabolism of valine in the malnourished rat: studies in vivo and in vitro with different labelled forms of valine

1. The catabolism of valine was estimated in vivo by measurement of the production of labelled CO2 for 2 h after the oral administration of either [U-14C] valine. It was also estimated in vitro in homogenates of liver and muscle incubated with labelled valine. Experiments were performed in rats given diets providing either 215 g (HP) or 25 g (LP) protein per kg diet. 2. The proportion of [U-14C] valine excreted as 14 CO2 was not reduced in rats given the LP diet for 16 d but the excretion of 14 CO 2 from [1-14C] valine was reduced by 40 percent in these animals. When rats were transferred from the HP diet to the LP diet there was a reduction in the excretion of 14CO2 from [1-14C] valine; when the diet was changed from LP to HP output of 14CO2 increased to control values. 3. Homogenates of muscle and liver catabolized valine to CO2. Both liver and muscle from rats fed on the LP diet catabolized less [1-14C] valine than tissues from control animals. 4. Valine aminotransferase activity was higher in muscle than in liver, and did not change in tissues from rats fed on the LP diet. In these animals 2-ketoisovaleric acid dehydrogenase activity was reduced in both liver and muscle. 5. The production of 14CO2 was lower with [U-14C] valine as the substrate than with [1-14C]-valine and there was no difference between tissues from rats fed on the HP and LP diets. 6. The results with [1-14C] valine suggest that both liver and muscle from protein-depleted rats catabolize valine at a reduced rate. The reason for the discrepancy between these results and those with [U-14C] valine is not clear. It is concluded that the results with [U-14C] valine in vitro are affected by dilution of the label before the formation of 14CO2, but that this does not hold in vivo (AU)

The catabolism of valine in the rat. The effects of protein calorie malnutrition in vivo and in vitro

A striking and consistent finding in the malnourished child is the very low level of valine in the plasma. It has been proposed that unaltered or increased catabolism of valine by skeletal muscle might account for this large reduction in the plasma valine concentration. In support of this hypothesis is the finding that the proportion of uniformly labelled valine (U-1 to 4th power C-valine) which is excretes as CO2 is the same in control and malnourished rats. Much of the label from U-1 to 4th power C-valine has to enter the Krebs cycle in order to be metabolised to CO2 and the results above may reflect the activity of this metabolic pathway. The formation of the labelled CO2 from valine labelled in the carboxylic acid group (1-1 to 4th power C-valine) reflects the activities of the first two enzymes in the catabolic pathway for valine. Malnourished rats excrete a lower proportion of a dose of 1-1 4th power C valine than do control rats. This result suggests that the specific part of the catabolic pathway of valine