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Lipids are considered the most important energy source in the infant diet and are necessary for normal growth and physical activity. Human milk, in which most of the energy is present as fat, provides a relatively high cholesterol intake. Formula provides a much lower cholesterol intake. Infants fed human milk have higher total and LDL-cholesterol concentrations in plasma than do formula-fed infants (P: < 0.05), whereas plasma HDL- and LDL-cholesterol concentrations are lower in formula-fed infants if a formula high in linoleate is fed (P: < 0.05). Infants adapt to the high cholesterol content of human milk through a decrease in cholesterol synthesis; in contrast, the addition of cholesterol to formula does not suppress synthesis. Measurements of serum lipoproteins and LDL-receptor activity suggest that it is the fatty acid content, rather than the cholesterol content, of the diet that regulates cholesterol homeostasis. We studied the effect of total energy, source of energy, and fat on growth indexes of children <6 y of age in Latin America with use of food balance data. With respect to availability of animal fat, a negative relation was evident for being underweight (percentage weight-for-age <2 SDs of the World Health Organization-National Center for Health Statistics standards) and for having a low birth weight; the latter was also negatively related to energy. Wasting (percentage weight-for-height <2 SDs) was not related to dietary factors. These results suggest that diets that provide <22% of energy from fat and that are low in animal fats may restrict growth. The coexistence of early stunting with adult obesity in Latin America creates a dilemma for public nutrition intervention programs.

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We report a 21-month-old female patient whose urine organic acid profile suggested a biotin utilization abnormality consistent with multiple carboxylase deficiency. For most previously reported patients, holocarboxylase synthetase deficiency has correlated with the early-onset variant of multiple carboxylase deficiency; conversely, biotinidase deficiency has been characteristic of the late-onset form. In vitro enzyme studies revealed that our patient suffered from holocarboxylase synthetase deficiency. We suggest that holocarboxylase synthetase deficiency should be considered in the differential diagnosis of older patients in whom there is suspicion of a defect in biotin metabolism.

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To evaluate the effect of varying phosphorus intake with constant high calcium intake (430 micrograms/kJ, or 180 mg/100 kcal), we randomly assigned 35 appropriate-for-gestational-age healthy male infants (birth weight, 715-1510 g) on day 21 postnatally to either standard-phosphorus (215 micrograms/kJ, or 90 mg/100 kcal), moderate-phosphorus (254 micrograms/kJ, or 106 mg/100 kcal), or high-phosphorus intake (287 micrograms/kJ, or 120 mg/100 kcal). Three-day mineral balances were determined after 7 d of the study diets. Weight and head circumference gain and intake of energy and vitamin D were not different for all groups. Calcium retentions were sufficient to meet intrauterine accretion in all groups. Phosphorus calculated to be available for soft tissue was significantly higher in the moderate- and high-phosphorus groups, and was sufficient to support soft tissue phosphorus accretion in these two groups. Total absorbed phosphorus and phosphorus tubular reabsorption were each affected by phosphorus intake. We conclude that very low birth weight infants fed high calcium may require greater phosphorus intake than that provided by formulas containing a ratio of calcium to phosphorus of 2:1. We suggest that the optimal mass ratio of calcium to phosphorus for formula for very low birth weight infants is from 1.6:1 to 1.8:1.

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A prospective study in healthy infants predefining both diet fatty acid and cholesterol, from birth to age 1 year, compared response of cholesterol fractions in three groups: random assignment to 1) monounsaturated-(Hi-Mono) (n = 20), or 2) polyunsaturated-(Hi-Poly) (n = 22) fatty acid-enriched diets, or 3) non-randomized selection to breast feeding (Human Milk) (n = 25). In each group, designated weaning foods and supplements maintained fatty acid and cholesterol intake similar to that of each group's defined formulas, with long-term compliance confirmed by plasma phospholipid fatty acid concentrations. By 12 months, total cholesterol was significantly lower in the Hi-Poly group compared to either of the other groups (P < 0.05). Low density lipoprotein (LDL)- and high density lipoprotein (HDL)-cholesterol concentrations were significantly lower by 12 months in the Hi-Poly group, compared to the Hi-Mono groups. However, at the earlier 4-month interval, total cholesterol and LDL-cholesterol in both Hi-Mono and Hi-Poly groups were not different from each other, although each was significantly lower than the parallel Human Milk-group (P < 0.05). The Hi-Mono group increased gradually in total and LDL-cholesterol such that, after 12 months' feedings, all lipid fractions of this Hi-Mono group were no different from those of the Human Milk group. In independent group comparisons, there were no significant differences in HDL-cholesterol concentrations after 4 and 9 months on these diets. Independent of diet, HDL-cholesterol showed a falling trend as an overall time-effect across all groups (P < 0.001). These data suggest that prolonged feeding of a diet enriched in polyunsaturated acids in early infancy has a significant cholesterol-lowering effect compared to monounsaturates. These differences in total, LDL-, and HDL-cholesterol plasma concentrations between polyunsaturates and monounsaturates were not significantly evident until feedings had continued for a year.

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3-Methylglutaconic aciduria was detected in four patients with Pearson syndrome, a multitissue disorder with hematologic abnormalities, lactic acidosis resulting from defective oxidative phosphorylation, and deletions in the mitochondrial genome. 3-Methylglutaconic acid may be an additional useful marker for Pearson syndrome and may be a more specific marker than other organic acids identified in this disorder.

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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.

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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.

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The Pearson marrow-pancreas syndrome is a fatal disorder involving the hematopoietic system and the exocrine pancreas in early infancy. We have previously shown that this disease results from a widespread defect of oxidative phosphorylation. Here, we describe deletions of the mitochondrial (mt) genome between repeated 8- to 13-bp sequences as consistent features of the disease. Studying a series of nine unrelated children, including the patient originally reported by H. Pearson, we found five different types of direct repeats at the boundaries of the mtDNA deletions and we provided evidence for conservation of the 3'-repeated sequence in the deletions. In addition, we found a certain degree of homology between the nucleotide composition of the direct repeats and several structures normally involved in mtDNA replication and mtRNA processing. These results are consistent either with the recognition and cleavage of a particular DNA sequence with a factor of still unknown origin or with a homologous recombination between direct-repeat mtDNA sequences in the Pearson syndrome.

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The clinical and magnetic resonance imaging findings of a 14-year-old boy with Pearson syndrome are presented. The patient represents the oldest living survivor of the original four patients described by Pearson and associates. This syndrome has recently been found to be associated with an mtDNA deletion. The patient reported here has a deletion similar but not identical to that reported in the literature. Several mitochondrial myopathies have been associated with mtDNA deletions, with considerable overlap between and among the phenotypes and underlying mtDNA deletions. The same may well prove to be true for Pearson syndrome.

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To address the role of high-energy phosphorus compounds in the hypotonia of vitamin D-dependent rickets, nuclear magnetic resonance spectra were obtained sequentially from resting gastrocnemius muscle of a 10-month-old infant with rachitic hypotonia during supplementation with vitamin D, calcium, and phosphorus. During the initial weeks of treatment, the hypotonia resolved before evidence of epiphyseal mineralization. Over the early treatment period, the muscle phosphocreatine/beta-adenosine triphosphate [PCr/beta-ATP] ratio increased from 2.7-2.8 [wk 1-2] to 3.9-4.5 [wk 7-9]. The PCr/beta-ATP ratio for 6-month-old normal infant gastrocnemius and adult forearm were 4.0 and 5.7, respectively. Muscle strength appeared to recover concomitantly with an increase in retained muscle phosphorus and high-energy phosphate compounds, and with relative increase in the muscle phosphocreatine to ATP ratio. The synchrony of clinical recovery may relate to the recovery kinetics of these metabolic changes.

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The Registry of Cytogenetic Abnormalities and Phenylketonuria (ReCAP) is a multicenter collaborative registry of information on patients with constitutional cytogenetic abnormalities or hyperphenylalaninemia (HPA). Data are entered by microcomputer at four contributing centers. Records are then electronically transmitted to the coordinating center, where the composite cytogenetic and hyperphenylalaninemia databases are maintained on a mainframe computer. A set of programs, known as the ReCAP ISCN Translator, is used to create additional database records describing in detail the chromosome abnormalities present in each patient. The ReCAP computer system permits rapid and flexible retrieval of cases on the basis of any combination of laboratory, clinical, psychometric, or genetic characteristics contained within the databases. Special procedures protect patient confidentiality and assure that ReCAP data are of consistently high quality. Qualified investigators may use ReCAP as a resource for a variety of scientific studies.

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Although photon absorptiometry is increasingly used to evaluate bone mineral content of neonates, its reliability in this age group is unclear. The midradius or middistal radius of 12 growing preterm infants was scanned, using a Norland 278 Densitometer. Proper examiner technique and densitometer calibration were first verified. In three infants, the bone edges were not consistently discernible from soft tissue. In the remaining nine infants, apparatus variability (the percent change in bone mineral content of scans repeated without repositioning the infant) was comparable to intraexaminer and interexaminer variability (determined after the same or a different examiner repositioned the infant and repeated the scan). The variability for successive scans ranged from -73% to +60% (SD, 5% to 36%). Adequate reliability for preterm infants remains to be documented for commercially available photon absorptiometers by in vivo studies.

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Banked human milk has been widely used, although its composition and nutritional adequacy for preterm infants are uncertain. We randomized 76 healthy infants of less than or equal to 1500 gm birth weight to ad lib feedings of frozen BHM or a protein-mineral-calorie-enriched formula (Similac Special Care) designed to sustain intrauterine accretion rates; BHM contained 2.2 gm fat/100 ml and 60 kcal/100 ml (gross energy). Infants fed BHM ingested more milk (197 vs 165 ml/kg/day) but less gross energy (118 vs 143 kcal/kg/day); grew less rapidly in weight (15 vs 30 gm/day), length (0.7 vs 1.1 cm/wk), and head circumference (0.8 vs 1.2 cm/wk); and were discharged at a lower weight (2200 vs 2348 gm) and older age (61 vs 47 day) than infants fed formula (P less than 0.02). At 37 weeks' postmenstrual age, infants fed BHM were less responsive to Brazelton inanimate stimuli (mean total score 5.0 vs 7.5; P less than 0.02). With few exceptions, blood amino acids, pH, and serum electrolyte values were similar in both groups. The different caloric intake of our feeding groups may explain only part of the large difference in growth rate. Donor milk should not be fed to preterm infants unless it has been analyzed and the feedings shown to provide a nutrient intake considered appropriate to the needs of these infants.

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