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Muscle protein degradation in premature human infants
Clinical Science (London, England : 1979)
|December 1, 1979
Summary
Muscle protein breakdown in premature infants is linked to nitrogen retention, not energy intake. Factors like weight change and mortality influence protein degradation rates, differing from adult responses.
Area of Science:
- Biochemistry
- Neonatology
- Pediatric Nutrition
Background:
- Premature infants have unique metabolic needs.
- Understanding muscle protein dynamics is crucial for infant growth and survival.
- 3-methylhistidine excretion is a validated marker for myofibrillar protein degradation.
Purpose of the Study:
- To quantify myofibrillar protein degradation in premature infants.
- To investigate the relationship between protein breakdown, nitrogen balance, and energy intake.
- To compare protein degradation patterns in premature infants with those in adults.
Main Methods:
- Measured 3-methylhistidine excretion in premature infants (635-1295 g).
- Conducted 1-3 day nitrogen balance studies.
- Analyzed correlations between protein breakdown rates, nitrogen retention, and energy input.
Main Results:
- Total muscle protein breakdown ranged from 0.70 to 2.58 g/day/kg (mean 1.05).
- Fractional muscle protein breakdown ranged from 3.3% to 8.3% daily (mean 4.8%).
- Higher protein degradation correlated with negative nitrogen balance and was elevated in infants losing weight or who died within two weeks.
Conclusions:
- Myofibrillar protein breakdown is negatively correlated with nitrogen retention in premature infants.
- Energy intake did not significantly correlate with protein degradation rates.
- Metabolic responses to nutritional status differ between premature infants and adults, possibly due to limited energy reserves.