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Biomedical subjects

T Heim

Publications and source records attributed to T Heim.

At least 37 records · Page 2Linked to original sources
PubMed1989

Effect of esophageal ligation on the growth of fetal rabbits.

Controversy continues regarding the nutritional value to the fetus of swallowed amniotic fluid. To clarify this issue further, esophageal ligations were performed to prevent deglutition in utero in 63 fetal rabbits during the final trimester of pregnancy. Compared with sham-operated littermate controls, the fetuses that were ligated for periods of 4, 5, or 6 days showed significant reductions in weight of 6.1, 18.9, and 9.2%, respectively. These results compare well with the magnitude of weight reduction seen clinically in patients with esophageal atresia. Significant but less consistent reductions were also noted in crown-rump length and biparietal diameter. No significant differences were seen in either body composition or gastrointestinal tract histology. These results indicate that swallowed amniotic fluid does play a role in fetal nutrition and may be particularly important in the later stages of gestation when placental function is limited.

Amniotic Fluid↗
PubMed1988

Characteristics of protein sparing effect of total parenteral nutrition in the surgical infant.

To determine the best formula to prevent protein depletion, 31 surgical infants on intravenous (IV) diet were studied. The study was divided into two phases. Phase I diet included 5% glucose and 1.5% or 2% amino acid infusion; phase II diet consisted of 5% glucose and 1.5% or 2% aminoacid plus 10% Intralipid. In each phase, oxygen consumption, carbon dioxide production, and energy expenditure were determined. The utilization of carbohydrate, fat, and protein was calculated from urinary nitrogen excretion and nonprotein respiratory quotient. The mean caloric intake during phase I and phase II was 62 and 94 kcal/kg/d, respectively. A positive nitrogen balance was obtained in infants receiving fat-free total parenteral nutrition (TPN) with a mean protein intake of 2.6 g/kg/d and a mean energy intake exceeding the energy expenditure by 24%. Infusion of more calories as Intralipid (phase II) caused a significant reduction in protein oxidation, thus protein contribution to the energy expenditure and an increase in protein retention. We conclude that supplementation of low-calorie TPN diets with Intralipid increases protein sparing and is preferable to the administration of very high glucose loads.

Amino Acids↗
PubMed1988

Evaluation of doubly labeled water for measuring energy expenditure during changing nutrition.

Change in abundance of 2H and 18O in dietary water during a doubly labeled water energy period may introduce error into the calculated carbon dioxide production rate (RCO2). To examine the accuracy of 2H2(18)O during changing nutritional regimens, we compared 2H2(18)O and periodic open-circuit respiratory gas exchange (RGE) in postsurgical infants who were changing from parenteral to alternative parenteral and/or oral nutrition. The two methods were compared before and after correction for shifts in isotopic abundance of the infant water pools during the energy-expenditure period. Baseline corrections were predicted using the difference between abundances of the initial body water and final nutrient solutions. Before isotopic correction, 2H2(18)O underestimated RCO2 in eight subjects by 11.8 +/- 20.1% (mean +/- SD). After correction, agreement between the two methods improved; the underestimate was then -8.7 +/- 12.9%. To obtain maximum precision of 2H2(18)O, subjects should be maintained on the same nutritional regimen before and during the study unless valid correction formulae are used.

Algorithms↗
PubMed1987

Injury severity, whole body protein turnover, and energy expenditure in pediatric trauma.

The purpose of this study was to quantify the changes in energy expenditure and protein turnover imposed by blunt trauma in children and to correlate them with the Injury Severity Score (ISS). We studied 19 children (mean age 10 +/- 1 year, mean ISS 20 +/- 2). Basal metabolic rate (BMR) was measured in the postabsorptive state by open-circuit indirect calorimetry. Whole body protein turnover (Q) and synthesis (S) were determined by the 15N enrichment of urinary ammonia in a 12-hour collection following a single dose of 15N glycine. Twelve-hour total urinary nitrogen excretion (E) was also determined. Because nitrogen intake was 0 during the study period, Q was equivalent to protein breakdown (B). Eleven patients were restudied at 3- to 5-day intervals during hospitalization and eight were restudied after discharge (mean 34 +/- 6 days post injury). There was a significant increase in BMR, Q, S, and E following injury, when compared with post injury baseline values. However, while BMR increased by 14%, there were 93% and 82% increases in Q (B) and S, respectively. Negative nitrogen balance resulted from the fact that protein breakdown increased more than protein synthesis. The initial increase in BMR varied directly with the severity of injury, as reflected in the ISS (r = 0.56, P less than .02). There was no significant correlation between ISS and any of the parameters of protein metabolism. These results suggest that the metabolic response of pediatric patients to multiple trauma may differ from that of adults. In addition, they imply that the ISS may not be a reliable indicator of the severity of tissue injury.

Adolescent↗
PubMed1987

Changes in the body composition of the surgical infant in the early postoperative period.

The purpose of this study was to evaluate the effects of postoperative nutritional management on the body composition of infants after major surgery. We studied 13 full-term surgical infants (mean initial weight 2.88 +/- 0.19 kg; mean days postsurgery 5.0 +/- 0.5). Ten infants were receiving total parenteral nutrition and three were orally fed (mean caloric intake 84 +/- 4 kcal/kg/d; mean fluid intake 145 +/- 4 mL/kg/d). Total body water (TBW) was measured by isotope dilution using heavy oxygen (18O) labeled water (H2(18)O). Total body fat (TBF) was estimated from anthropometric data. Lean body mass (LBM) was calculated as follows: LBM = weight--TBF. Protein, fat, and carbohydrate accretion were determined by energy and macronutrient balance in conjunction with open-circuit indirect calorimetry. Body composition was reevaluated after an interval of seven days. Body weight increased from 2.88 +/- 0.19 to 3.00 +/- 0.19 kg, representing a mean growth velocity of 5.9 g/kg/d. Increments were observed in all body compartments but only the increase in TBF reached statistic significance (12.9 v 14% of body weight, P less than .05). TBW ranged from an initial value of 76.2 +/- 1.4% to a value of 75.5 +/- 1.4% at the end of the study. Protein, fat, and carbohydrate accretion (g/kg/d) during the seven-day study period were 1.62 +/- 0.13; 1.44 +/- 0.41, and 0.96 +/- 0.70, respectively. These data indicate that in the early postoperative period, the weight gain is secondary to both water and solid tissue accretion. Fat represents the major form of energy storage in the new tissues synthesized.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Composition↗
PubMed1987

Validation of doubly labeled water for assessing energy expenditure in infants.

Previous studies show that the doubly labeled water method is accurate for measuring energy expenditure in the adult human. To validate this method in infants, carbon dioxide production rate and energy expenditure were measured for 5 to 6 days by doubly labeled water (DLW) and periodic open circuit respiratory gas exchange (RGE) in 10 blinded studies in nine infants following abdominal surgery. Infants were maintained on consistent oral or parenteral nutrition prior to and during study. This avoided diet-related changes in baseline isotopic enrichment of body water which could theoretically contribute to significant errors in calculation of carbon dioxide production rate. For DLW, insensible water loss was assumed to be proportional to respiratory volume and body surface area, where the former was predicted from carbon dioxide production rate. Insensible water loss thus calculated averaged 18% of water turnover. Rates of carbon dioxide production measured by DLW were not significantly different from that of RGE (10.4 +/- 1.1 and 10.5 +/- 0.9 l/kg/day, mean +/- SD, respectively). Energy expenditure was calculated using respiratory quotients from dietary intake (DLW:DIET) and RGE (DLW:RGE) data. There was no significant difference between energy expenditure determined by DLW (DLW:DIET and DLW:RGE) and that measured by RGE (58.5 +/- 6.1, 56.8 +/- 6.1, and 57.3 +/- 5.1 kcal/kg/day, mean +/- SD, respectively). Rate of carbon dioxide production, DLW:diet, and DLW:RGE calculated by DLW differed from corresponding RGE values by -0.9 +/- 6.2, -1.1 +/- 6.1, and 1.6 +/- 6.2%, mean +/- SD, respectively. These findings demonstrate the validity of the doubly labeled water method for determining energy expenditure in infants without concurrent water balance studies.

Absorption↗
PubMed1985

How to meet the lipid requirements of the premature infant.

Through effective use of tables and illustrations, the author discusses the lipid requirements of the premature infant and how these requirements may be met by examining the lipid composition of human milk and colostrum, cow's milk, infant formula, vegetable oils, and premature-infant formula. Also discussed are the variables that affect the composition of human milk and the question of term versus preterm milk.

Adult↗
PubMed1984

Metabolic consequences of intrauterine growth retardation in very low birthweight infants.

By the combination of energy and macronutrient balances, continuous open circuit computerized indirect calorimetry, and anthropometry, we have compared small for gestational age (SGA) and appropriate for gestational age (AGA) very low birthweight infants with respect to metabolizable energy intake (mean +/- SE: 125.9 +/- 2.5 versus 130.4 +/- 3.5 kcal/kg X day), energy expenditure (67.4 +/- 1.3 versus 62.6 +/- 0.9 kcal/kg X day), storage of energy and macronutrients and growth. Fourteen studies in six SGA infants (gestational age, 33.1 +/- 0.3 weeks; birthweight, 1120 +/- 30 g) and 22 studies in 13 AGA infants (gestational age, 29.3 +/- 0.4 weeks; birthweight, 1155 +/- 40 g) were performed. The SGA infants had a lower absorption of fat (68.7 +/- 3.2 versus 79.7 +/- 1.7%) and protein (69.1 +/- 3.2 versus 83.4 +/- 1.5%) and hence increased (P less than 0.001) energy loss in excreta (29.9 +/- 2.8 versus 18.2 +/- 1.5 kcal/kg X day). The significant hypermetabolism of SGA infants by 4.8 kcal/kg X day was associated with an increased fat oxidation. Despite lower energy storage, SGA infants were gaining weight (19.4 +/- 0.9 g/kg X day), length (1.25 +/- 0.14 cm/week), and head circumference (1.16 +/- 0.9 cm/week) at higher rates than the AGA group. The energy storage per g weight gain was lower (P less than 0.001) in the SGA group (3.0 +/- 0.14 versus 4.26 +/- 0.26 kcal) reflecting higher water, lower fat (22.2 +/- 1.8 versus 33.8 +/- 2.5%; P less than 0.001) and lower protein (7.7 +/- 0.5 versus 12.5 +/- 0.8%; P less than 0.001) contents of weight gain in the SGA group.

Body Weight↗
PubMed1983

Transfer of [3H]pyrrolizidine alkaloids from Senecio vulgaris L. and metabolites into rat milk and tissues.

[3H]Retronecine and [3H]necic acid-labelled senecionine and seneciphylline were prepared biosynthetically with seedlings of Senecio vulgaris L. using [2,3-3H]putrescine and [4,5-3H]isoleucine, respectively, as precursors. Lactating rats dosed with these differently labelled pyrrolizidine alkaloids (PAs) excreted within 3 h approx. 0.08% of the applied radioactivity in the milk mainly as yet not identified water-soluble retronecine-derived metabolites and with approx. 0.02% as unchanged PAs. Highest tissue levels of PAs and metabolites, 6 h after administration, were found in liver and lungs.

Animals↗
PubMed1983

Quality of growth in premature infants fed their own mothers' milk.

With the renewed interest in the feeding of human milk to preterm infants, we have evaluated the partition of energy metabolism and of macronutrient utilization and accretion in growing very low birth weight infants fed their own mother's milk. Fifteen studies combining macronutrient balance, computerized continuous open-circuit indirect calorimetry, and anthropometric measurements were performed in 11 growing, very low birth weight (less than 1.300 gm) preterm infants. The mean milk intake of 172 ml/kg/day provided a gross energy intake of 111 kcal/kg/day. Energy losses in excreta were 11 kcal/kg/day, and the metabolic energy expenditure was 56 kcal/kg/day. The remainder (44 kcal/kg/day) represented the energy stored in the components of new tissue. The infants were gaining weight (15.3 g/kg/day), length (0.98 cm/wk), and head circumference (0.76 cm/wk) at rates approximating intrauterine growth rates. The metabolic energy expenditure was derived from the oxidation (mean +/- SE) of carbohydrate, 9.5 +/- 0.7 gm/kg/day; fat, 1.63 +/- 0.34 gm/kg/day; and protein, 0.68 +/- 0.07 gm/kg/day. The stored energy comprised 2.98 +/- 0.86 gm/kg/day as carbohydrate, 2.25 +/- 0.54 gm/kg/day as fat, and 1.97 +/- 0.1 gm/kg/day as protein. The accretion rates of fat and protein, as well as the composition of the weight gain (fat, 16.6 +/- 4.1%; protein, 13.4 +/- 0.5%), were similar to those reported for the fetus of comparable gestational age.

Anthropometry↗
PubMed1983

Dietary composition and macronutrient storage in preterm infants.

A comparison has been made of the influence of feeding own mother's milk and formula on the oxidation and accretion of energy and macronutrients in the growing preterm infant of very low birth weight (less than 1,300 g) by using the combined techniques of nutrient balance and computerized indirect calorimetry. There were 22 studies in formula-fed infants and 15 studies in premature infants fed own mother's milk. Despite their lower metabolizable energy intake, the infants fed own mother's milk grew in weight, length, and head circumference at a rate approximating those of the formula-fed group. The metabolic rate was significantly lower in the infants fed own mother's milk (56.0 +/- 0.9 v 62.6 +/- 0.8 kcal/kg/d; P less than .001). The protein intake, oxidation, and accretion were similar in the two groups. The infants fed own mother's milk had a significantly lower fat intake (P less than .001), higher fat oxidation (P less than .025) and consequently lower fat accretion (P less than .001) than the formula-fed infants. The proportional fat content of the daily weight gain was lower in the infants fed own mother's milk (16% v 33%; P less than .001) but protein content was similar (13% v 12%). The accretion of energy, fat, and protein correlated with the respective metabolizable intakes in both groups (r = .81 to .98; P less than .001), suggesting that accretion rates and hence composition of weight gain are dependent on levels of energy and macronutrient intake.

Animals↗
PubMed1982

Partition of energy metabolism and energy cost of growth in the very low-birth-weight infant.

Energy requirements are partitioned between needs for maintenance (including resting metabolism, thermoregulation, and muscular activity) and needs for synthesis and storage of new tissue. The partition of energy utilization was evaluated by 22 metabolic and nutritional balance studies in 13 formula-fed (SMA 20/24), growing, appropriate-for-gestational age, very low-birth-weight infants (mean +/- SE birth weight, 1,155 +/- 39 gm; study weight, 1,271 +/- 60 gm; age at study, 21 +/- 2 days; weight gain, 16.8 +/- 1 gm/kg/day). Continuous open-circuit, indirect calorimetry was performed for periods of 6 +/- 0.25 hours in a thermoneutral environment. Results expressed as mean kilocalories per kilogram per day (+/- SE) were: energy intake, 148.6 (+/- 3.9); stool and urine losses, 18.2 (+/- 1.5); metabolizable energy, 130.4 (+/- 3.5); "basal" metabolic rate, 47.0 (+/- 0.75); energy cost of activity, 4.3 (+/- 0.9); thermic effect of food, 11.3 (+/- 0.65); energy stored in new tissue, 67.8 (+/- 3.0). These results provide a partition of energy utilization in very low-birth-weight infants under thermoneutral conditions. Increased activity and a thermal environment outside the neutral range will augment maintenance energy requirements, thus decreasing the amount of energy available for growth if metabolizable energy intake remains constant. The energy cost of growth (ie, for synthesis of, and storage in, new tissue) was determined as 4.9 kcal/gm of weight gain. To attain the equivalent rate of intrauterine weight gain, a metabolizable energy intake of approximately 60 kcal/kg/day in excess of maintenance requirements of 51.3 kcal/dk/day must be provided.

Anthropometry↗
PubMed1981

Diet, fat accretion, and growth in premature infants.

To compare the growth and accumulation of protein, fat, and carbohydrate in the formula-fed premature infant and in the fetus of a similar postconceptional age, we performed 22 metabolic studies in 13 infants of very low birth weight (1155 +/- 39 g [mean +/- S.E.]). Measurements combining nutritional balance and indirect calorimetry demonstrated the deposition rates of protein and fat. We found that the formula-fed, very-low-birth-weight infant who gained weight comparably to the fetus retained the same amount of protein (1.92 +/- 0.1 g per kilogram of body weight per day) but accumulated fat at a rate of 5.4 +/- 0.3 g per kilogram per day - about three times that in the fetus, as confirmed by increased skin-fold thickness. How this change in body composition affects the future growth of formula-fed premature infants, and how body composition is altered by other dietary regimens such as the provision of human milk, remain to be determined.

Anthropometry↗