Search PubMed⌕ Search

Biomedical subjects

R Uauy

Publications and source records attributed to R Uauy.

At least 91 records · Page 5Linked to original sources
PubMed1992

Muscle phosphorus energy state in very-low-birth-weight infants: effect of exercise.

Skeletal muscle hypotonia is a hallmark clinical finding in very-low-birth-weight (VLBW) human infants. Although the biochemical basis for this phenomenon is not completely understood, one hypothesis is that the phosphorylation potential is abnormally low in the skeletal muscle of these infants. Therefore, we used 31P-nuclear magnetic resonance (NMR) spectroscopy to measure phosphorus metabolites in the skeletal muscle of VLBW infants during rest and during reflex-induced muscle contractions. Compared with healthy larger infants or to adults, the total phosphorus NMR signal is lower in VLBW infants. In VLBW infants during rest, [PCr]/([PCr]+[Pi]), where PCr is phosphocreatine and brackets denote concentration, was 89% and [ATP]/[ADP][Pi] was 59% of that found in larger infants (P less than 0.05). During reflex-induced isometric contractions in VLBW infants, [PCr]/([PCr]+[Pi]) declined by 24% and [ATP]/[ADP][Pi] declined by 35% (P less than 0.05 vs. rest). In all conditions, muscle pH remained 7.1. Overall, the differences in skeletal muscle energy state during rest and the corresponding changes in concentration of high-energy phosphates during mild exercise suggest a very limited energy reserve in the hypotonic muscle of VLBW infants.

Adenosine Diphosphate↗
PubMed1992

Effects of increased dietary phosphorus on magnesium balance in very low birthweight babies.

The effects of three dietary phosphorus concentrations on magnesium balance in very low birth weight (VLBW) infants were measured. The infants consumed one of three special formulas for 20 consecutive days. Magnesium balance was calculated by measuring food intake, urinary magnesium and fecal magnesium. The highest dietary phosphorus concentration resulted in a higher (P < 0.05) fecal loss of magnesium. Net absorption and net retention of magnesium were lower (P < 0.10) in the high phosphorus group. A modest (33 per cent) increase in dietary phosphorus resulted in a decrease in magnesium absorption in VLBW infants.

Absorption↗
PubMed1992

Dietary essential fatty acid supply and visual acuity development.

The influence of dietary omega-3 fatty acid supply on visual acuity development was evaluated in very low birth weight (VLBW) infants using visual-evoked potential (VEP) and forced-choice preferential-looking (FPL) procedures at 36 and 57 wk postconception. The VLBW infants born at 27-33 wk postconception were randomized to one of three diet groups: corn oil, which provided solely linoleic acid; soy oil, which provided linoleic and alpha-linolenic acids; or soy/marine oil; which was similar to the soy oil formula but also provided preformed long chain omega-3 fatty acids. The VLBW infants in the soy/marine oil group had higher omega-3 levels in erythrocyte membranes and better VEP and FPL acuities at 36 and 57 wk than infants in the corn oil group. The soy oil group had intermediate omega-3 levels in erythrocyte membranes and significantly poorer VEP acuity at 57 wk compared with the soy/marine oil group. Only the soy/marine oil group had acuities comparable to the "gold standards" of VLBW infants fed human milk and preterm infants who were born and tested at 35-36 wk postconception. In addition, VEP and FPL acuity were poorer in a nonrandomized group of formula-fed full-term infants than in breast-fed full-term infants. The results suggest that dietary omega-3 fatty acid supply may play an important role in early human visual development.

Breast Feeding↗
PubMed1992

Adaptation of feeding to a low fat yield in breast milk.

The effect of a low milk fat yield was assessed in a blinded prospective study of healthy term infants and mothers encouraged to breast-feed. Fat yield index was calculated as milk volume collected by Egnell pump multiplied by the "creamatocrit." Two weeks after delivery mothers who had a relatively low fat yield index (less than or equal to 30th percentile) were matched with mothers with a higher fat yield index and with formula-feeding mothers. Between 2 and 6 weeks the low fat yield group had a marginally lower weight gain but similar growth in length and head circumference to that of the higher fat yield group. The low fat yield group spent more time per feeding and had more complete breast emptying, resulting in a fat yield index comparable with the higher fat yield group for the mean milk volume ingested by the infant at 6 weeks. A low fat yield had no adverse effect on maternal satisfaction or maternal-infant interaction during feeding. Formula feeders spent the least time in feeding and en face gazing. Adaptation of breast-feeding to a low fat yield sustains infant intake and growth, maternal-infant interaction, and maternal satisfaction. However, there is little reserve if milk production diminishes. Further study is needed to define the limits of adaptation and effective interventions if fat yield is inadequate.

Breast Feeding↗
PubMed1991

Metabolic tolerance to arginine: implications for the safe use of arginine salt-aztreonam combination in the neonatal period.

Two similar cohorts of low birth weight infants whose size was appropriate for gestational age randomly received either aztreonam-arginine plus ampicillin (n = 15) or gentamicin plus ampicillin (n = 15) for empiric treatment of neonatal sepsis. The regimens were infused together with glucose at greater than 5 mg/kg per minute, and immediate (4 hours) and cumulative (3 days) effects were assessed. Serum arginine and insulin values rose immediately after administration of aztreonam (containing 0.15 mmol of arginine per kilogram), but there were no changes in the gentamicin-treated cohort; no differences occurred in either cohort in serum concentrations of glucose, ammonia, potassium, creatinine, and bilirubin. After 3 days of antibiotic therapy (n = 13), the baseline serum arginine concentration was almost twice as high in the aztreonam group and showed a similar further rise and fall during the 4 hours after infusion; arginine urinary fractional excretion (normalized to creatinine clearance) decreased in the gentamicin group. The indirect bilirubin concentration rose more (p less than 0.001) in the aztreonam-treated infants (5.1 to 11.5 mg/dl (87 to 196 mumol/L] than in the gentamicin-treated infants (5.5 to 8.1 mg/dl (94 to 138 mumol/L)). Thus a modest differential bilirubin response and modestly elevated baseline serum arginine level occurred after the 3-day low-arginine doses of this study; serum ammonia and glucose concentrations were not affected. Aztreonam-arginine in neonates was well tolerated metabolically, and we believe that it can be used safely in conjunction with attention to glucose and bilirubin metabolism.

Ammonia↗
PubMed1991

Body composition of low-birth-weight infants determined by using bioelectrical resistance and reactance.

We tested the hypothesis that bioelectrical resistance and reactance are indices of total body water (TBW) and extracellular water (ECW), respectively. Infants less than 2500 g in birth weight were studied while less than 24 h old and at 4-7 d of age. TBW (n = 32) was measured by H2(18)O dilution and ECW (n = 34), by bromide dilution. Measurements were made by using an impedance plethysmograph from each of four electrode pairs. Bioelectrical resistance correlated inversely with TBW (r = -0.683). When body weight and crown-heel length were factored into the equation, the correlation improved (r = 0.953). Bioelectrical reactance correlated inversely with ECW (r = -0.707). When body weight and surface area were factored into the equation the correlation improved (r = 0.882). We conclude that bioelectrical resistance and reactance are good indices of TBW and ECW, respectively. However, the ability to resolve small changes in body-water compartments when confined to the intraluminal or other third spaces remains questionable, particularly for single subjects.

Body Composition↗
PubMed1991

Neuropsychological function in young children who have undergone liver transplantation.

Presented neuropsychological data from 20 patients between the ages of 4 and 9 years, who had undergone liver transplantation at least 12 months prior to study participation, and compared them to a control group of 20 children with cystic fibrosis. The liver transplant group showed deficits in VIQ, PIQ, visual-spatial and abstraction/reasoning skills, but not in alertness/concentration, motor, or sensory-perceptual functions. On motor and sensory-perceptual tests, no differences were found in direction of lateralization of deficits. Visual-spatial deficits found in this study sample are similar to those found in adults with end-stage liver disease and in a previous report of an overall older group of children following liver transplantation. However younger children have greater evidence of generalized impairment and VIQ deficits which have not been found in older groups. Findings are discussed in relation to possible etiology, location of brain damage, and clinical implications.

Brain Damage, Chronic↗
PubMed1991

Coinheritance of two mild defects in low density lipoprotein receptor function produces severe hypercholesterolemia.

A family is described in which the probands, twin girls, had severe hypercholesterolemia suggestive of familial hypercholesterolemia (FH). The mother of the twins had normal plasma cholesterol levels, and the father had only moderate hypercholesterolemia. Moreover, low density lipoprotein (LDL) binding studies in cultured fibroblasts and isolated lymphocytes in the parents failed to reveal significantly reduced LDL receptor activity that is typical of FH heterozygotes. Turnover studies of LDL in the parents, however, revealed low fractional clearance rates (FCRs) for LDL. In cultured fibroblasts and isolated lymphocytes from the twin probands, binding of normal LDL was half normal or less. LDL turnover studies in the twins revealed a marked reduction in FCRs for LDL. When the twins were treated with lovastatin, however, FCRs for LDL increased significantly, suggesting enhancement of LDL receptor activity. This finding along with LDL binding studies in the cultured cells infer that the twins did not have homozygous FH. In addition, all family members tested negative for familial defective apolipoprotein-B-100, and LDL isolated from the mother and twins showed normal binding to normal fibroblasts. The overall data suggest that the severe hypercholesterolemia in the offspring was due to inheritance of mild to moderate defects of LDL receptor function from both parents. Although the latter defects could not be detected with certainty by in vitro tests in each parent, they were evident from LDL turnover tests. Coinheritance of these defects apparently produced severe hypercholesterolemia in the offspring.

Apolipoproteins B↗
PubMed1991

Neuropsychological outcome of pediatric liver transplantation.

Children with end-stage liver disease who undergo liver transplantation may have unrecognized neuropsychological and academic deficits, for which remediation programs may be available. Intellectual, academic, and neuropsychological measures of 28 pediatric patients who had received successful liver transplantation at least 1 year previously were compared with those of 18 patients with cystic fibrosis (to control for effects of growth retardation and chronic illness) matched for age, age at diagnosis, physical growth, and parents' socioeconomic status. Liver transplant patients had significantly lower scores on nonverbal intelligence tests (mean +/- SD for liver transplant vs cystic fibrosis patients: 89.1 +/- 19.1 vs 105.8 +/- 17.6), lower academic achievement, and lower zeta scores for age in the areas of learning and memory (-0.68 +/- 1.09 vs 0.19 +/- 1.24), abstraction and concept formation (-1.73 +/- 1.58 vs -0.79 +/- 1.37), visual-spatial function (-0.66 +/- 1.09 vs 0.10 +/- 0.69), and motor function (-0.13 +/- 0.85 vs 0.36 +/- 0.57). No differences were found on tests of verbal intelligence, or in alertness and concentration, perceptual-motor, and sensory-perceptual areas. Cyclosporine levels were found to correlate positively with motor speed (r = .41, P less than .05). Thorough psycho-educational and neuropsychological evaluations should be considered for pediatric patients who receive liver transplantation to allow these children to maximize their potential.

Adolescent↗
PubMed1990

Oral copper supplementation: effect on copper and zinc balance during acute gastroenteritis in infants.

To evaluate the effect of copper supplementation during recovery from acute diarrhea, we randomly assigned 14 hospitalized infants to receive either 80 micrograms copper sulfate.kg body wt-1.d-1 or a placebo. Metabolic balance and plasma copper and zinc concentrations were measured before randomization (period 1) and 6 d after admission (period 2). Fifteen control subjects were studied after respiratory illness. Fecal copper was not affected by supplementation; fecal zinc during period 2 rose significantly only in the copper-supplemented group. Copper retention was significantly higher in the supplemented infants; plasma concentrations increased for period 2 but were similar to those in the placebo group. Zinc concentrations improved over time in both groups but zinc retention was higher in the placebo group for period 2. A significant interference by copper supplementation on zinc absorption was noted. Copper supplementation during the early phase of recovery from diarrhea is not recommended.

Acute Disease↗
PubMed1990

Maternal weight gain in low-income black and Hispanic women: evaluation by use of weight-for-height near term.

This study determined the prevalence of low maternal weight gain among a target group of low-income black and Hispanic women and compared weight-for-height near term with total weight gain during pregnancy as an index of birth-weight classification. One-third (30.8%) of 325 women had weights near term less than 120% of their standard pregravid weight-for-height; there was little variation by ethnic group. After adjusting for gestational age as a covariate of birth weight (P = 0.0001), maternal weight-for-height near term (P = 0.0010), ethnicity (P " 0.0068), and parity (P = 0.0083) significantly influenced birth weight. Women with near-term weights greater than or equal to 120% of their standard pregravid weight-for-height delivered infants with higher birth weights (P = 0.001). Comparison of weight-for-height near term with total weight gain as an index of birth-weight classification (less than or greater than or equal to 3000 g) revealed that the two methods differ in terms of sensitivity and specificity with variation in pregravid weight.

Adolescent↗
PubMed1990

Protein-energy requirements of prepubertal school-age boys determined by using the nitrogen-balance response to a mixed-protein diet.

Short-term nitrogen-balance response to a vegetable-protein mixed diet and to a milk-egg protein diet was tested in eight healthy male children 8-10 y old. They received 96, 128, 160, and 192 mg N.kg body wt-1.d-1 for 10 d while on the mixed diet and 160 mg N.kg-1.d-1 on the milk-egg diet. The mean regression equation was nitrogen balance = 0.52 (nitrogen intake) -68.3, all in mg N.kg-1.d-1. Apparent nitrogen digestibility was 82% and 86% for the mixed and milk-egg diets, respectively, when the subjects received 160 mg N.kg-1.d-1. Mean nitrogen intake for satisfactory nitrogen retention on the mixed diet was 150 mg N.kg-1.d-1; the suggested protein recommended allowance to cover 97.5% of the population was derived by using a CV of 12.5% is 1.2 g protein.kg-1.d-1. We conclude that present recommendations are adequate for short-term nitrogen retention; long-term studies are needed to evaluate the chronic safety of this protein allowance.

Analysis of Variance↗
PubMed1990

Effect of dietary nucleosides on growth and maturation of the developing gut in the rat.

Dietary nucleoside (DN) as a precursor for nucleic acid synthesis may be important for rapidly dividing cells, since gut epithelial cells have limited capacity for de novo purine and pyrimidine synthesis. We evaluated in a controlled blinded study the effect of added nucleosides, 0.8% by weight, given for 2 weeks, on gut growth and maturation in 20 weanling rats. Mucosal protein and DNA in the proximal intestinal segment were 50% and 77% higher, respectively, in the DN-supplemented group (n = 10; p less than 0.05). Villus height based on cell count was 25% greater in the DN group (p less than 0.05). Maltase activity was significantly greater in proximal, middle, and distal intestinal segments, and the largest increase, 87%, was seen in the proximal gut mucosa. The maltase/lactase ratio was also higher in this segment. Increases in sucrase were less prominent. Lactase was minimally affected. The pattern of change in disaccharidase activity suggests that DN may enhance gut growth and maturation of the intestine in the weanling rat, the effects being more pronounced in the proximal segment. Diets free of nucleosides and nitrogenous bases may have adverse effects on the gut.

Animals↗
PubMed1989

The effect of intestinal anastomosis on gut growth and maturation.

We evaluated the effect of intestinal anastomosis without resection on gut morphometry (muscle thickness, villus height, and crypt depth), growth indices (DNA, protein, and protein:DNA ratio), and disaccharidase activity (maltase, sucrase, and lactase) in the growing animal. A group of 10 weanling Sprague-Dawley rats at 21 days of age was subjected to intestinal transection and anastomosis in the upper jejunum, 10 cm distal to the ligament of Treitz. A second group of 10 similar rats was used as a control group. All rats were fed a regular diet and kept under the same conditions. They were sacrificed 2 weeks later. Body weight, intestinal weight, and intestinal length measurements were obtained. The intestine was divided into two sections: preanastomotic (section A) and postanastomotic (section B) in the surgery group and equivalent sections A and B in the control group. Specimens were subjected to morphometric evaluation and mucosal scrapings for biochemical analysis. Despite significant weight gain in the control group, there were no differences in intestinal length, intestinal weight, and mucosal weight between the two groups. Muscle thickness, villus height, and crypt depth were significantly increased in the preanastomotic segment. Protein and DNA were also higher in the preanastomotic segment, but the protein:DNA ratio was less affected. There was significantly decreased enzymatic activity in the preanastomotic segment. Intestinal anastomosis has a significant effect on gut growth and maturation in the growing animal and may have important implications in the postoperative management of newborns and infants following intestinal surgery.

Anastomosis, Surgical↗