Search PubMed⌕ Search

Biomedical subjects

W C Heird

Publications and source records attributed to W C Heird.

At least 55 records · Page 3Linked to original sources
PubMed1990

Growth, nutrient retention, and metabolic response of low-birth-weight infants fed supplemented and unsupplemented preterm human milk.

Growth, nutrient retention, and metabolic response of low-birth-weight infants fed human milk provided by their mother; this milk supplemented with bovine milk protein, calcium, phosphorus, and sodium; or pasteurized term human milk with the same supplement were monitored from the time desired intake was tolerated until weight reached 2200 g. The supplement resulted in greater rates of weight gain (20.5 +/- 2.3 vs 16.4 +/- 2.2 g.kg-1.d-1) and nitrogen retention (353 +/- 76 vs 270 +/- 53 mg.kg-1.d-1), increase in plasma transthyretin (TTR) concentration (7 +/- 16 vs -3 +/- 9 mg.L-1.wk-1), a higher mean plasma albumin concentration (34 +/- 3 vs 32 +/- 4 g/L), and a higher plasma TTR concentration at discharge (100 +/- 22 vs 75 +/- 24 mg/L). All these variables correlated significantly with total nitrogen intake, suggesting that the differences are attributable to the protein content of the supplement. The supplement also resulted in greater rates of calcium and phosphorus accretion but the plasma alkaline phosphatase activity of the supplemented vs the unsupplemented groups did not differ.

Alkaline Phosphatase↗
PubMed1990

Antiviral and antibacterial lipids in human milk and infant formula feeds.

Human milk and two infant formula feeds were tested for antiviral and antibacterial activity before being given to 21 low birthweight (LBW) infants; neither was present. When samples were aspirated from the stomachs of the infants within one to three hours of feeding, however, they reduced titres of enveloped virus and also killed both Staphylococcus epidermidis and Escherichia coli. The lipid fraction of the gastric aspirate from an infant who had been given human milk as well as those from four infants who had been given a conventional LBW infant formula feed, showed antiviral and antibacterial activities at least equal to the activities of the unfractionated aspirates. There was no consistent difference in antiviral or antibacterial activity of either the stomach aspirates or the lipid fractions of these aspirates between infants given human milk and those given formula feeds. The antiviral and antibacterial activities of the gastric aspirates seem to result from intragastric production of monoglycerides and fatty acids from the triglyceride content of the ingested feeds.

Antiviral Agents↗
PubMed1988

Growth, nutrient retention, and metabolic response in low birth weight infants fed varying intakes of protein and energy.

Growth, nutrient retention, and metabolic response were determined in low birth weight (LBW) infants fed daily protein and energy intakes, respectively, of 2.8 gm/kg and 119 kcal/kg (group 1), 3.8 gm/kg and 120 kcal/kg (group 2), and 3.9 gm/kg and 142 kcal/kg (group 3). The mean rates of both weight gain and nitrogen retention in group 1 were somewhat greater than intrauterine rates; plasma concentrations of transthyretin and albumin also were acceptable. Thus the lower protein intake appeared to be adequate. On the other hand, the rates of weight gain and nitrogen retention in groups 2 and 3 were greater than those in group 1, supporting the efficacy of the higher protein intake with respect to growth. However, blood urea nitrogen and plasma amino acid concentrations also were higher in groups 2 and 3; both were higher in group 2 than in group 3, reflecting the positive effect of the higher energy intake on protein utilization. This observation, combined with data from an earlier study, indicates that protein intakes in excess of 3 gm/100 kcal will not be utilized completely. Energy expenditure in group 3 was greater than in group 1 but not group 2, raising the possibility that protein intakes not utilized completely contribute to diet-induced thermogenesis. The higher energy intake in group 3 vs group 2 did not affect rate of weight gain significantly, but energy storage in group 3, and hence fat accretion, was greater than that of other groups. In all groups the ratio of protein accretion to fat accretion reflected dietary proportions of protein and energy.

Child Development↗
PubMed1988

Pediatric parenteral amino acid mixture in low birth weight infants.

A mixture of amino acids designed to maintain normal plasma amino acid concentrations in infants and children requiring parenteral nutrition was evaluated in 28 low birth weight (LBW) infants (birth weight, 750 to 1750 g; postnatal age, 1 to 4 weeks) who required parenteral nutrients for optimal nutritional management. Sixteen babies received only parenteral nutrients for five to 21 days. Ten of these received a typical regimen by peripheral vein (1.91 +/- 0.16 g/kg/d of amino acids and 44.7 +/- 4.4 kcal/kg/d) and six received a typical regimen through a central vein (2.39 +/- 0.11 g/kg/d of amino acids and 95.9 +/- 14.5 kcal/kg/d). Mean weight gain of the peripheral vein subgroup was 10.3 +/- 10.6 g/kg/d; mean nitrogen balance was 230 +/- 66 mg/kg/d. Both the mean rate of weight gain (17.2 +/- 5.1 g/kg/d) and the mean rate of nitrogen retention (267 +/- 49 g/kg/d) of the central vein subgroup were similar to intrauterine rates. In these two subgroups as well as the total population, plasma concentrations of all amino acids except phenylalanine were within the 95% confidence limits of the plasma concentrations observed in LBW infants fed sufficient amounts of human milk to result in a rate of weight gain similar to the intrauterine rate. However, although plasma tyrosine and cyst(e)ine concentrations were within the 95% confidence limits of the plasma concentrations goals, the LBW infant's ability to use N-acetyl-L-tyrosine and cysteine HCl appears to be even less than that of the term infant and older child. In toto, these data support the efficacy of the amino acid mixture evaluated for LBW infants. Of equal importance, they suggest that the LBW infant's ability to use parenterally delivered amino acids is not as limited as commonly thought.

Amino Acids↗
PubMed1987

Energy expenditure, energy balance, and composition of weight gain in low birth weight infants fed diets of different protein and energy content.

The effect of energy and protein intakes on energy expenditure, energy balance, and amount and relative rate of both protein and fat deposition in new tissue was investigated in 19 low birth weight infants whose mean protein and energy intakes, respectively, were 2.24 g/kg/d and 113 kcal/kg/d (formula A, n = 8), 3.6 g/kg/d and 115 kcal/kg/d (formula B, n = 5), and 3.5 g/kg/d and 149 kcal/kg/d (formula C, n = 6). The higher energy intake (formula C) but not the higher protein intake (formula B) resulted in greater energy expenditure. Both the higher protein (formula B vs formula A) and higher energy intakes (formula C vs formula B) resulted in greater weight gain secondary, in group B, to a greater absolute rate of protein deposition and, in group C, to a greater absolute rate of fat deposition. The relative composition of the new tissue deposited reflected the proportional intakes of protein and energy. The numerical value of the protein/fat ratio (g/g) of the new tissue deposited by infants fed formulas A and C, the protein contents of which were low relative to energy contents, were similar and significantly lower than the numerical value of the protein/fat ratio of the new tissue deposited by infants fed formula B, which had a higher protein content relative to energy content. These findings suggest that the composition of weight gain is related to both the absolute amounts and the proportions of dietary protein and energy; thus, both must be considered in formulation of nutritional regimens for LBW infants.

Body Weight↗
PubMed1987

Amino acid mixture designed to maintain normal plasma amino acid patterns in infants and children requiring parenteral nutrition.

A mixture of amino acids designed to maintain normal plasma amino acid concentrations of infants and children requiring parenteral nutrition was evaluated in 40 infants and children receiving only parenteral nutrients (2.39 +/- 0.26 g/kg/d of amino acids and 110.3 +/- 10.4 kcal/kg/d) for five to 21 days. The children ranged in weight from 2.0 to 12.6 kg (median weight, 3.83 kg; fifth to 95th percentile, 2.06 to 11.1 kg) and in age from 1 week to 43.6 months (median age, 2.7 months; fifth to 95th percentile, 0.2 to 25.3 months). Mean weight gain was 11.0 +/- 5.0 g/kg/d; mean nitrogen balance was 242 +/- 70 mg/kg/d. Plasma concentrations of all amino acids except tyrosine were within the normal range (ie, within the 95% confidence limits of the two-hour postprandial plasma concentrations observed in 30-day-old, healthy, normally growing, breast-fed, term infants) throughout the period of study. Mean prestudy and poststudy serum total protein, albumin, and transthyretin (prealbumin) concentrations were not significantly different. However, plasma transthyretin concentration increased in all children with low prestudy concentrations. Mean poststudy serum total bilirubin concentration of the total population was not different from the mean prestudy concentration. This was true also for the 31 children who received the parenteral amino acid mixture for more than ten days. In contrast to the expected 30% to 50% incidence of cholestasis, only one of these 31 experienced an unexplained increase in serum total bilirubin concentration during study, suggesting that normalizing plasma amino acid concentrations and/or providing taurine during parenteral nutrition may decrease the incidence of cholestasis associated with this therapy.

Amino Acids↗
PubMed1987

Protein quality in feeding low birth weight infants: a comparison of whey-predominant versus casein-predominant formulas.

Growth (delta weight, delta length, delta head circumference, and delta skinfold thickness), nitrogen retention, and chemical indices of metabolic tolerance (BUN concentration and acid-base status; plasma amino acid concentrations including free and bound cyst(e)ine; urinary excretion of sulfur amino acids) were determined serially in low birth weight infants (900 to 1,750 g) fed formulas differing only in protein quality. One contained unmodified bovine milk protein (a ratio of whey proteins to caseins of 18:82); the other contained modified bovine milk protein (a ratio of whey proteins to caseins of 60:40). Both provided protein and energy intakes, respectively, of approximately 3.4 g/kg/d and 120 kcal/kg/d. Neither weight gain nor the rate of increase in length, head circumference, and skinfold thickness differed between the two groups. Nitrogen retention of the two groups also did not differ. Although BUN concentration and blood acid-base status did not differ, there were differences in the plasma concentrations of some amino acids. Plasma tyrosine concentration was higher in infants fed the casein-predominant protein, and plasma threonine concentration was higher in infants fed the whey-predominant protein. Neither plasma-free nor bound cyst(e)ine concentration differed between the two groups, but the greater cyst(e)ine intake of the whey-predominant group resulted in greater cyst(e)ine retention; this was accompanied by greater urinary taurine excretion, a reflection of greater taurine stores.

Acid-Base Equilibrium↗
PubMed1986

Effects of varying protein and energy intakes on growth and metabolic response in low birth weight infants.

Growth (weight, length, head circumference, and skinfold thickness), retention of major nutrients (nitrogen, sodium, potassium, chloride, calcium, and phosphorus), and chemical indices of protein adequacy (plasma albumin and transthyretin concentrations) and excess (blood urea nitrogen concentration and acid-base status; plasma amino acid concentrations) were determined serially from the time desired intake was tolerated until discharge weight (2200 gm) was reached in low birth weight infants (birth weight 900 to 1750 gm) fed one of three formulas, which provided protein and energy intakes, respectively, of 2.24 gm/kg/day and 115 kcal/kg/day (group 1), 3.6 gm/kg/day and 115 kcal/kg/day (group 2), and 3.5 gm/kg/day and 149 kcal/kg/day (group 3). Weight gain and rate of increase in length and head circumference were less in group 1 than in groups 2 and 3. Retention of most major nutrients also was less in group 1, as was blood urea nitrogen concentration, plasma albumin and transthyretin concentrations, and plasma concentrations of several amino acids. The rate of weight gain was not significantly greater in group 3 than in group 2, but the rate of increase in skinfold thickness was greater in this group. Neither nutrient retention nor metabolic indices differed between groups 2 and 3. These results suggest that a protein intake of 2.24 gm/kg/day is inadequate for the type of LBW infants studied, that the higher protein intakes are well tolerated, and that an energy intake of 149 vs 115 kcal/kg/day does not enhance utilization of the higher protein intakes studied.

Acid-Base Equilibrium↗
PubMed1984

Role of taurine in feeding the low-birth-weight infant.

Plasma and urinary taurine concentrations, growth, nitrogen balance, duodenal bile salt concentration and pattern, fecal bile acid excretion, and intestinal fat absorption were determined in appropriate for gestational age low-birth-weight infants fed either a whey-predominant cow milk formula or the same formula supplemented with taurine (45 mumol/kg/day). Mean plasma taurine concentration in the two groups did not differ. Mean urinary taurine concentration in the control and supplemented groups over the entire study period were 2.67 +/- 0.69 and 12.41 +/- 5.20 mumol/dl, respectively (P less than 0.05). Urinary taurine concentration in the supplemented infants, however, decreased significantly during the study period. Neither growth nor nitrogen retention differed between the two groups. Mean duodenal concentrations of taurine as well as glycine conjugates of both cholate and chenodeoxycholate were higher in supplemented infants. Total duodenal bile salt concentration correlated positively with taurine status as reflected by urinary taurine excretion (r = 0.71); this correlation plus the lower duodenal cholesterol concentration in supplemented infants suggests that conversion of cholesterol to bile acids was greater in supplemented infants. Mean intestinal fat absorption in control and supplemented infants, however, did not differ.

Bile Acids and Salts↗
PubMed1984

Short-term pulmonary effects of total parenteral nutrition in children with cystic fibrosis.

Indices of respiratory muscle strength, pulmonary function, and pulmonary diffusing capacity were measured in 11 malnourished children (age 10 to 17 years) with cystic fibrosis, before and after improvement of nutritional status with supplemental parenteral nutrients for 1 month. During this time, the children received 120% of estimated energy requirements (either 3.75% or 22.5% as lipid) and amino acids 2.5 gm/120 kcal by central venous catheter, plus as much of their usual diet as desired. With nutritional supplementation, body weight, triceps skinfold thickness, and mid-arm muscle circumference increased (mean 15%, 62%, and 95%, respectively). Maximum inspiratory airway pressure also increased (mean 29%; P less than 0.01), suggesting improvement in respiratory muscle strength. However, none of the indices of pulmonary function improved. Pulmonary diffusing capacity did not change during parenteral nutrition regardless of the amount of parenteral energy intake supplied by lipid, but arterial oxygen saturation decreased (mean of 93.5% to 91.5%; P less than 0.005). During the month following parenteral nutrition, weight, skinfold thickness, and mid-arm muscle circumference, but not MIP, decreased and arterial oxygen saturation returned to the initial value (P less than 0.01).

Adolescent↗
PubMed1984

Colostrum-induced enteric mucosal growth in beagle puppies.

To evaluate the role of artificial feeding and natural feeding in early growth of enteric mucosa, we determined enteric mucosal mass, protein and DNA content, and disaccharidase activities in beagle puppies at birth, and after 24 h of either natural or artificial feeding. Despite similar increases in body weight over the first 24 h of life, neither mucosal mass, DNA content, nor protein content of the artificially fed animals was different from that of newborn animals. In contrast, mucosal mass of the suckled animals was 75% greater, DNA content was 56% greater, and protein content was 93% greater than that of newborn animals. The mucosal protein/DNA ratio of the suckled animals was greater than that of newborn, but not artificially fed animals. The greater DNA, protein, and protein/DNA ratio in this group suggest that the greater mucosal mass is a result of both cellular hyperplasia and hypertrophy. Sucrase specific activity of the suckled animals was less than that of the artificially fed but not the newborn animals. Other disaccharidase activities were not different among the three groups. These data extend the findings of Widdowson et al.(25) to another species and demonstrate that this rapid enteric growth over the first day of life results only from natural feeding. They strongly suggest, therefore, that rapid early enteric growth, mediated perhaps by a factor in natural milk that stimulates enteric mucosal growth, is an important heretofore unappreciated phase of intestinal development.

Animals↗
PubMed1984

History of parenteral nutrition in pediatrics with emphasis on amino acids.

Central venous total parenteral nutrition (TPN) has proved to be a valuable and often life-saving measure in selected newborn infants with surgically repairable, major anomalies of the gastrointestinal tract and infants with chronic intractable diarrhea. However, in infants of low--and especially very low--birth weight, the TPN regimen that was so successful in older infants was frequently associated with severe risks of hyperglycemia. An alternative approach that has proved to be the most satisfactory relies on the fact that the energy expenditure of a premature infant, nursing in a thermally neutral environment, rarely exceeds 50 kcal/kg, a level that can be safely and effectively maintained. With respect to the development of parenteral amino acid solutions, three generations of such mixtures can now be identified. The first of these was represented by the protein hydrolysates. With the advent of technology for the production of pure L-amino acids, a second generation of crystalline mixtures was developed. Evaluation of these revealed that extrapolation from data on oral nutrition was often unsatisfactory for the adequate formulation of such mixtures. The direct study of the parenterally nourished patient led to the third generation of special purpose amino acid solutions such as those targeted for patients with renal failure, liver failure, or trauma or for the promotion of anabolism. It seems likely that development of other solutions will follow the trend of relying on accurate definition of a given metabolic disorder and the perfection of a specific solution to correct it.

Amino Acids↗
PubMed1982

Use of medium-chain triglycerides in feeding the low-birth-weight infant.

Intestinal fat absorption and anthropometric and clinical variables were monitored weekly in 21 low-birth-weight (LBW) infants fed either a whey-predominant cow's-milk formula (formula 1) or identical formulas with medium-chain triglycerides (MCTs) comprising 40% (formula 2) or 80% (formula 3) of the fat content. Fat absorption of infants fed formula 1 averaged 86.7% of intake, whereas that of infants fed formulas 2 and 3 averaged 93.8% and 95.4%, respectively. However, no differences in weight, length, head circumference, or skin fold thickness were observed. Moreover, intestinal symptoms were encountered more frequently in infants fed formulas 2 and 3. This demonstrated failure of the resulting small increase in fat absorption incident to MCTs either to promote enhanced growth or to confer obvious clinical benefit does not support the increasing use of MCT formulas for routine feeding of LBW infants.

Diet Therapy↗