Summarvuse could potentially result in an increase in plasma free fatty Net nitrogen retention (NNR) and rates of whole-body protein turnover (Q), synthesis, and breakdown (B) were measured in 24 intravenously fed premature infants, birthweight
There has been renewed interest in examining the multiple causes of undernutrition and growth failure in cystic fibrosis. It is now recognized that undernutrition is caused by unfavourable energy balance rather than an inherent component of the disease. Furthermore, there appears to be a direct association between the degree of undernutrition and the severity of pulmonary disease, which in turn affects overall prognosis. Energy imbalance may be caused by three main factors: increased energy loss because of nutrient maldigestion; reduced energy intake due to an improper diet and/or anorexia from respiratory disease, abdominal symptoms or clinical depression and increased energy expenditure with advanced lung disease. Most patients are capable of compensating for these factors; provided energy intake is sufficient, normal growth velocity and nutritional status is maintained. However, in a minority of older patients, when advanced lung disease supervenes, energy expenditure rises resulting in an energy deficit. Undernutrition, with loss of energy stores and lean tissue may in turn contribute to progressive deterioration of lung function. When this occurs, long-term invasive methods of nutritional support can restore energy balance.
The effect of a test diet of conventional North American foods on breath 13CO2 abundance was determined in 4 healthy males. Subjects consumed a diet containing 41.9% energy as fat and a polyunsaturated:saturated fatty acid ratio of 0.217 for 5 days at a level equal to estimated requirements for total energy. One subject underwent four 5-day feeding periods. Over the feeding period mean change in subjects' body weight was -0.165 +/- 0.64% (means +/- SEM) of initial body weight. On day 5 breath samples were collected hourly from 0745 to 1645 h and analyzed for 13CO2 enrichment relative to the pre-breakfast fasted state (level at 0745 h). Breakfast and lunch were consumed at 0820 and 1300 h respectively. Mean enrichment peaked at 1445 h at 0.00311 atom % excess above fasting level for all subjects and 0.00243 atom % excess for the four repeated trials on one subject. Between subject variation (SEM) in 13CO2 enrichment (0.000618 atom %) was significantly greater than within subject variation (0.000308 atom %). These results indicate that ingestion of normal meals during the breath test period increases breath 13CO2 abundance due to a shift in substrate oxidation. The small within subject variation in repeated 13CO2 enrichment profiles indicates the reliability of 13C breath tests using controlled diets. It is concluded that for tests conducted under identical conditions, an initial background 13CO2 abundance profile determined once for each subject, can be subtracted from the subsequent enrichment profile generated by a labeled test substrate.
We have examined the effect of the route of feeding (intravenous versus enteral) on the protein metabolism of postsurgical human neonates. Twelve infants, birth weight 2.5 +/- 0.2 kg, gestational age 38 +/- 1 wk, were studied. The IV study was carried out 1-4 days after surgery at a postnatal age of 14 days and a weight of 2.6 +/- 0.2 kg. The repeat (oral) study was carried out 16 days later. Protein intakes were similar during both studies (2.7 g/kg/d). Energy intakes were within the requirement range for age and feeding route and were: IV, 85 +/- 4 kcal/kg/d; oral, 111 +/- 7 kcal/kg/d. Whole body protein metabolism was studied using a continuous infusion of 15N-glycine. Amino nitrogen flux, protein synthesis, and breakdown were 40% higher during the enteral than the IV studies (p less than 0.001). Skeletal muscle degradation was investigated by measuring urinary excretion of creatinine and N-T-methylhistidine. No differences were detected due to feeding route. We suggest that the differences seen in whole body protein turnover rates reflect the rapid growth and development of the gut in the enterally (rather than the IV) fed infant.
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