Effect of docosahexaenoic acid content of maternal diet on auditory brainstem conduction times in rat pups.

Previous studies of dietary docosahexaenoic acid (DHA; 22:6n-3) effects on neurodevelopment have focused mainly on effects on the visual system; these studies may be confounded by effects on the retina rather than on neural pathways. Auditory brainstem conduction times (ABCTs) provide an alternate measure of central neural development. We conducted a dose-response study in which ABCTs were measured in pups whose dams were fed diets containing one of three levels of DHA (2, 4 or 6% of total fatty acids) from a single cell oil. Diets were fed during pregnancy and lactation, and pups were randomly cross-fostered on postnatal day 3 to minimize litter effects. ABCTs showed a dose-response effect, with higher levels of dietary DHA being associated with longer conduction times on postnatal day 31 (p < 0.05). Higher dietary DHA was reflected in pup cerebrums collected on postnatal days 3 and 31, and levels of arachidonic acid (AA, 20:4n-6) were inversely related to levels of DHA. This study demonstrated that the auditory brainstem response is sensitive for identifying effects of diet on neurodevelopment, and that supplementing the maternal diet with high levels of DHA may negatively impact development of the central auditory system of offspring.

Transcutaneous absorption of vitamin A in newborn rats.

Very low birth weight neonates have low tissue concentrations of vitamin A, which may contribute to the development of lung disease. These infants, however, may not receive vitamin A supplementation for several days after birth. We determined if the relatively permeable skin of a newborn could be used to administer vitamin A. 25 control rat pups were killed and lungs and livers were collected. 20 microl (1,000 IU) of retinyl palmitate were applied to the skin surface of an additional 50 two-day-old pups. At 2.5 and 5 h after application, 25 pups were killed, and lungs and livers were collected. Concentrations of retinyl palmitate and retinol were significantly higher in the lungs of pups 5 h after administration of vitamin A compared with controls. There were no differences in concentrations of retinyl palmitate or retinol in livers. We conclude that transcutaneous administration may be an effective means of delivering vitamin A to the lungs of newborn rats.

Isovaleric acidemia with promyelocytic myeloproliferative syndrome.

Isovaleric acidemia, an autosomal recessive disorder, is due to isovaleryl-coenzyme A dehydrogenase deficiency and is one of the branched-chain aminoacidopathies. Isovaleric acidemia may present in the neonatal period with an acute episode of severe metabolic acidosis, ketosis, and vomiting and may lead to coma and death in the first 2 months of life. This report concerns an infant who presented at 10 days of age because of lethargy, poor feeding, hypothermia, cholestasis, and thrombocytopenia, leukopenia, and profound pancytopenia. Death occurred at 19 days of age. Autopsy showed mild fatty change in the liver and extramedullary hematopoiesis, generalized Escherichia coli sepsis, and myelodysplasia of the bone marrow with arrest of the myeloid series at the promyelocytic stage. The appearance resembled promyelocytic leukemia, but the diagnostic 15:17 translocation was not present. The maturation arrest in granulopoiesis in isovaleric acidemia appears to be most likely due to a direct metabolic effect on granulocyte precursor cells.

Postnatal inositol levels in preterm infants.

OBJECTIVE: To measure plasma inositol levels in preterm infants fed formula containing inositol at levels close to those in human milk. STUDY DESIGN: Plasma inositol levels were measured in 72 preterm infants fed formula containing 1110 mumol/L inositol and in cord blood of 12 healthy term infants. Preterm infant plasma levels were measured four times: (1) within the first 7 days of life, (2) intermediate enteral feeding, (3) at hospital discharge, and (4) 2 months after hospital discharge. RESULTS: Inositol concentrations in term cord blood samples were significantly lower than in preterm initial feeding, intermediate feeding, and discharge samples. Initial concentrations in blood of preterm infants were higher than in all other groups, and were significantly lower among infants with gestational ages of 31 to 33 weeks compared with those of 28 to 30 or 31 to 33 weeks. Days of parenteral nutrition were a significant predictor of inositol levels in the full feeding sample, with lower levels associated with prolonged parenteral nutrition. Clinical outcomes were not related to plasma inositol levels. CONCLUSIONS: Feeding preterm formula with inositol levels close to those reported for human milk may not prevent the postnatal decline in preterm infant plasma inositol levels.

Functional methionine synthase deficiency due to cblG disorder: a report of two patients and a review.

Functional methionine synthase deficiency due to abnormal methylcobalamin metabolism causes megaloblastic anemia, moderate to severe developmental delay, lethargy, and anorexia in association with homocystinuria. Patients with this disorder of cobalamin metabolism can be classified into two separate groups, cblE or cblG, primarily on the basis of complementation analysis with cultured skin fibroblasts. We describe two unrelated boys, ages 3 and 5 years, with the cblG defect in methylcobalamin synthesis. Both children presented with severe developmental delay, lethargy, anorexia, and megaloblastic anemia. The diagnosis of homocystinuria was delayed in each case due to difficulties with detection of small amounts of homocystine in physiologic samples. The clinical course of cblG disease is favorably altered by treatment with intramuscular hydroxycobalamin. Megaloblastosis in the presence of adequate supplies of cobalamin and folate in the blood must alert the clinician to the possibility of functional methionine synthase deficiency and should prompt a careful search for associated biochemical hallmarks, including homocystinuria/emia.

Trophic factors for the gastrointestinal tract.

GI trophic factors that influence the coordinated pre- and postnatal growth and development of the GI tract have been identified. Studies in animals and humans demonstrate that GI trophic factors can initiate cellular growth and expression of differentiated function, and they are important in adaptation and repair following injury. Systemically as well as enterally administered growth factors can stimulate GI growth and maturation, suggesting that trophic factors in the serum of neonates may modulate GI growth via receptors on the serosal membranes of enterocytes. GI trophic factors may be synthesized endogenously or provided postnatally in milk. GI trophic factors in human milk play an important role in regulating the adaptive functional changes that accompany the transition to postnatal enteral feedings. Although human milk growth factors do not appear to be essential for infant survival, the elevated risk of gastrointestinal-related illnesses in formula-fed as compared with breast-fed infants (diarrhea, necrotizing enterocolitis, colitis, Crohn's disease) suggest that bioactive compounds in human milk contribute to the apparent protective effect of breast feeding. GI trophic factors have the potential to be used therapeutically to enhance GI maturation and repair following injury. These applications may be particularly useful in the premature or postsurgical infant. Several issues require further research, including (1) the mechanism of action, (2) the efficacy of oral versus systemic administration, (3) characterization of the complex interactions between the various growth factors, because some appear to act synergistically, (4) the effect of exogenously administered growth factors on endogenous production of that factor, its receptor, or other growth factors, (5) the effect of growth factors upon tissues not directly associated with the GI tract, and (6) the determination of safe and effective upper limits.

Analyzing signs and symptoms of metabolic diseases.

Inborn metabolic errors, while not common, may have significant implications for patients. Those patients with such errors who have acute life-threatening symptoms must be treated immediately, and specimens for analysis should best be obtained during the critical stage. Many infants and children seen with acute symptoms are the ones most likely to have treatable diseases. At a more leisurely pace, other inborn errors can be diagnosed in order to provide appropriate counseling and prognosis.

Nutritional requirements of infants and children with respect to cholesterol and related compounds.

Cholesterol is an enigmatic, essential metabolite. Breast milk contains significant quantities of cholesterol, yet human infants thrive on cholesterol-free diets. Recommendations to lower serum cholesterol are widespread, yet low serum cholesterol is associated with poorly understood morbidity. Serum cholesterol is increased with diets high in fat, yet dietary cholesterol has relatively little effect on serum concentrations. Smith-Lemli-Opitz syndrome, marked with extremely low serum cholesterol, may serve as a human model for the evaluation of absorption and metabolism of dietary cholesterol.

Dietary nucleotides affect hepatic growth and composition in the weanling mouse.

The effect of dietary nucleotides upon hepatic growth and composition was examined in weanling mice. For 5 weeks, mice were fed either Purina Rat Chow, a nucleotide-free diet (NT-), a nucleotide-free diet supplemented with a mixture of five nucleotides (0.21% w/w), (NT+) or a nucleotide-free diet supplemented with adenosine 5'-monophosphate (0.0425% w/w) (NTA). Hepatic cholesterol and lipid phosphorous were significantly higher, whereas liver weight (expressed as a percentage of body weight), and glycogen were lower in animals fed NT- vs all other groups. NTA-fed animals presented a greater contrast to the NT- group than did animals fed the mixture of nucleotides. Liver fatty acid composition and distribution of phospholipid subclasses were not affected by dietary nucleotide supplementation. Dietary nucleotide supplementation in weanling mice affects hepatic growth and composition; adenosine 5'-monophosphate may play a unique role in these effects.

Dietary sources of nucleotides--from breast milk to weaning.

Human breast milk contains large quantities of nucleotides compared with those in cow's milk and infant formulas. Dietary nucleotides may have significant effects in infants.