Nitrogen balance and protein turnover during the growth failure in newly born low-birth-weight infants.
Weight gain, nitrogen balance, protein turnover, and energy and protein intakes were measured during the first week of life of 14 low-birth-weight (LBW) infants, 5 small-for-gestational-age (SGA) infants and 9 appropriate-for-gestational-age (AGA) infants enterally fed at rates determined by the infants ability to assimilate feed. Mean gross intakes were 334 KJ and 1.75 g/kg protein; 4 infants were increasing and 10 were losing weight at rates proportional to gross energy and protein intakes and to nitrogen balance (0.031 g protein balance/g wt gain). Rates of protein synthesis and degradation measured by an intragastric infusion of [1-13C]leucine, averaged 14.5 and 15.9 g protein.kg-1.d-1, some 50% higher than previously reported in older preterm infants and not correlated with nitrogen balance. The growth failure of these infants was not associated with inadequate overall rates of protein turnover, but appeared to reflect an influence of the insufficient energy and protein intakes on the high rates of protein turnover, inducing changes in protein balance in either direction through relatively small changes in protein synthesis and/or degradation.
Kandil
H
H
High Institute of Public Health, University of Alexandria, Egypt.
Darwish
O
O
Hammad
S
S
Zagloul
N
N
Halliday
D
D
Millward
J
J
D004044:Dietary Proteins / Q000008:administration & dosage; D004435:Eating; D002149:Energy Intake; D006801:Humans; D007230:Infant, Low Birth Weight / Q000254:growth & development*; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development*; D007236:Infant, Small for Gestational Age / Q000254:growth & development*; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D015430:Weight Gain
D004044:Dietary Proteins; D011506:Proteins; D009584:Nitrogen