Hwai-Ping Sheng

Human Milk Protein Does Not Limit Growth of Breast-Fed Infants

BACKGROUND The efficiency with which breast- and formula-fed infants utilize dietary nutrients is likely to provide insight into their relative requirements for the growth process. METHODS We measured longitudinal changes in growth, body composition, and dietary intakes in breast- and formula-fed infants and estimated the gross efficiency with which dietary nitrogen and energy were used for lean body mass and body fat deposition. Lean body mass and body fat were determined in 10 breast-fed and 10 formula-fed infants at 6-week intervals during the first 24 weeks of life by the 18O dilution technique. Dietary nitrogen and energy intakes were determined from the amount of milk and food consumed and the nutrient content of the feedings. The gross efficiency of nutrient utilization was calculated for each infant from the cumulative dietary intake and the change in body composition with time. RESULTS Length and weight gains and lean body mass and body fat accretion during the first 24 weeks of life were similar between breast- and formula-fed infants despite significantly higher nitrogen and energy intakes of the formula-fed group. The gross efficiency of dietary nitrogen utilization for lean body mass deposition was almost two-fold lower in formula- than in breast-fed infants, whereas the efficiency of dietary energy utilization for lean body mass and body fat deposition was similar between groups. Despite apparent differences in the efficiency of nitrogen utilization, there was no association between lean body mass deposition and dietary protein intake, implying that human milk protein does not limit growth quantitatively in breast-fed infants. CONCLUSIONS These differences in nutrient utilization illustrate the biologic adaptability of human infants who are equipped with mechanisms that promote normal growth despite the variability of their nutrient intake.

Liver composition and histology in growing infant miniature pigs given different total parenteral nutrition fuel mixes.

Although young infants are at greater risk for total parenteral nutrition (TPN)-related liver disease than adults, previous studies on the effect of the TPN energy source on the development of hepatic steatosis have been carried out in adult rats and adult humans. We studied the effect of a glucose and a glucose/fat TPN energy regimen on hepatic chemical composition and the development of steatosis in newborn miniature pigs. Twenty miniature pigs were randomized at 10 days of age to receive a TPN regimen which utilized either glucose (group A) or glucose/fat (group B) as the non-nitrogen energy source. After 8 days, blood was drawn for insulin, glucagon, SGPT, albumin, and bilirubin determinations. Samples of liver were obtained at 9 days. Plasma insulin levels were significantly higher and glucagon levels lower in group A piglets than in those in group B. Normal values were obtained for SGPT, albumin, and bilirubin, and no differences were found between groups. Chemical analysis of the livers revealed no differences between groups in the concentrations of glycogen, fat, protein, DNA, and RNA. Group A animals had significantly higher concentrations of water than group B (group A: 0.75 +/- 0.01 liter/kg; group B: 0.74 +/- 0.01; p less than 0.03). A significant correlation was found in group B between the plasma insulin/glucagon ratio and the hepatic glycogen concentration (r = 0.73, p less than 0.05). Group A animals had fat vacuoles in centrilobular hepatocytes, in contrast with group B animals who had visible fat only in Kupffer cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Different Total Parenteral Nutrition Fuel Mixes on the Body Composition of Infant Miniature Pigs

Summary: At 10 d of age miniature pigs were randomized to receive either of two total parenteral nutrition fuel mixes; oral feedings were discontinued. Both groups received 170 kcal·kg-1·d-1 and 11 g·kg-1·d-1 of synthetic amino acids. Nonprotein energy was supplied as glucose in group A, whereas in group B, it was divided equally between glucose and fat. Blood samples were drawn on the second and eighth postoperative days for hematologic, biochemical, and hormonal measurements. On the ninth postoperative day, total body water was determined and the animals were killed for carcass analysis. The animals tolerated the intravenous nutrition without ill effects as indicated by both clinical and biochemical parameters. Group A had significantly elevated levels of insulin and a higher insulin/glucagon ratio than group B. Cortisol levels did not differ significantly between groups. Total body fat, nitrogen, ash, K, Na, Cl, Ca, and P were similar between groups. TBW was significantly greater in group A compared with group B. Extracellular space calculated from body Cl and plasma Cl was similar between groups.

Pitfalls of Body Fat Assessments in Premature Infants by Anthropometry

Subcutaneous fat mass (SFM) and total fat mass (TFM) were estimated in 16 preterm infants at 8 +/- 2 days postnatal age. SFM was estimated from anthropometric measurements: 5 skinfold thicknesses, 5 body circumferences, and regional body lengths. TFM was estimated from total body water measurements using dilution of isotopic water, H2(18)O. The proportion of TFM that was SFM decreased with an increase in TFM. In infants with less than 100 g of TFM (5% body weight), 74% of TFM is in the subcutaneous layer compared with only 35% in infants with higher TFM (more than 100 g). Subscapular skinfold thickness is the best predictor of TFM (r = 0.78). Additional skinfold thickness measurements (triceps, biceps, supra-iliac and thigh) do not improve the predictability of TFM by the subscapular skinfold thickness. We conclude that measurement of subscapular skinfold thickness is an appropriate choice for estimating fat deposition in preterm infants, particularly in field studies and in developing countries.

In vivo measurements of nitrogen, hydrogen, and carbon in genetically obese and lean pigs

Characteristic gamma-rays are emitted promptly by elements during exposure to neutrons. These emissions enable a radioanalytical analysis of the bodys composition of protein (nitrogen), water (hydrogen), and fat (carbon). We have used this method in vivo to determine the body composition of obese and lean pigs (10 to 20 kg body wt) fed an altered cholesterol diet.

Use of a resonating cavity to measure body volume

A technique to estimate the body volume of newborns has been developed using the principle of the Helmholtz resonator. The change in the resonance frequency of a small cavity after an infant is placed inside can be used to determine the body volume of the infant. A prototype system, termed an acoustic plethysmograph, was built and used to measure the volume of newborn miniature pigs. Results of the animal body volume measurements compare favorably (within an average of 1.1%) with body volumes measured by hydrostatic weighing.

Case report: failure to thrive in a breast-fed infant is associated with maternal dietary protein and energy restriction.

OBJECTIVE To determine whether failure to thrive in a breast-fed infant could be attributed to altered milk production or composition from a mother who consumed a self-imposed energy- and protein-restricted diet. DESIGN We evaluated the changes in growth and body composition, dietary intakes, and milk production and composition in a mother-infant pair throughout the first postpartum year. SETTING The Childrens Nutrition Research Center Metabolic Research Unit. SUBJECTS A breast-feeding mother-infant pair. MEASURES OF OUTCOME Body composition was measured by total body electrical conductance, dietary intakes by food records, milk production by the test weighing procedure, and milk composition by proximate analyses. RESULTS A marked decline in the infants linear and ponderal growth rates occurred when the mother consumed an energy- (20 kcal.kg-1.d-1) and protein- (0.7 g.kg-1.d-1) restricted diet. The retardation in body weight gain was associated with an arrest of body fat, but not lean body mass, accretion. Maternal milk production showed positive relationships with maternal dietary energy (p < 0.01, r = 0.93) and protein (p < 0.05, r = 0.83) intakes. Milk composition reflected changes consistent with those of weaning rather than a sequela of the mothers diet. CONCLUSIONS We concluded that failure to thrive in a breast-fed infant could be attributed to reduced milk production in conjunction with maternal dietary energy- and protein-restriction and that an assessment of maternal dietary intakes is essential in an evaluation of the breast-fed infant with failure to thrive.

Differences in energy intake affect body composition and adipose tissue accretion in young growing piglets

Abstract From d 7 to d 32 of age, piglets were fed one of three diets that varied in energy content: LE, lowest; IE, intermediate; and HE, highest. The protein, vitamin and mineral content was constant, the fat content varied, and the amount fed was on a body-weight basis. Body fat, adipose tissue fat and adipocyte size were proportional to energy intake. Adipocyte distribution was bimodal at d 32; cells 25 μm was larger in the LE than in the IE and HE groups.

Extracellular water estimated by the bromide dilution method from samples of urine, saliva, and plasma.

Bromide (Br) dilution has been used by many investigators to estimate extracellular water (ECW) (Cheek et al., 1984; Brans et al., 1904; Schaffer et al., 1987). The use of this method in infants, however, is often limited by the need to take multiple blood samples. Our present studies were designed to 1) evaluate the accuracy and precision of Br measurements in micro-volumes of body fluids using ion chromatography, and 2) investigate urine and saliva as alternatives to plasma for the estimation of Br dilution space.

Body Composition of the Neonate

Rapid growth in the human occurs during the fetal, infant, and latter pubertal stages of development. During these phases of growth, changes occur in the chemical and biochemical composition of the body and in its physiological functions. Growth of the fetus, in its protective intrauterine environment, is determined by its genetic potential and is influenced by the nutritional, hormonal, and health status of the mother. Most biochemical and physiological development studies of the fetus in utero have examined changes associated with the transition from in utero to the free-living neonate and the response to improvements in the clinical care of the preterm neonate. There is a body of chemical composition studies of fetal growth and development that contains data useful as standards for nutritional care of the preterm neonate. These data were obtained from whole body chemical analyses of the human fetus and neonate. The studies contain information about the influence of gestational age and maternal nutritional status on the chemical composition of the fetus.1–4