Chromatographic Separation and Characterization of LinkageIsomers of the 3-(Pyridin-2-yl)-l//-l,2,4-triazole Complex of Ruthenium(II) Bis(2,2-bipyridyl)
Development of supplementation guidelines for formulated diets and total parenteral nutrition requires knowledge of Se tissue accretion. To this end, the total organ Se content was calculated from the Se concentrations that were measured by neutron activation analysis in postmortem samples of liver (n=56), kidney (n=11), adrenal cortex (n=9), and pancreas (n=6) from infants and children from birth to 10 yr including 17 born prematurely. Hepatic Se concentrations were similar in full-term and premature newborns, decreased from birth to 1 yr, and then increased thereafter. The total hepatic Se content was significantly greater in full-term than in preterm newborns and increased with age and liver size after 1 yr. No significant differences were found between the concentrations of Se in kidney, pancreas, and adrenal tissues. Falling hepatic Se concentrations in the full-term infant concurrent with stable total organ Se content may indicate inadequate dietary intake or may reflect a normal redistribution of the nutrient. Premature infants are born with smaller stores than full-term infants and are at greater risk of developing a deficiency.
Zinc deficiency is well described in infants on total parenteral nutrition (TPN). Urinary Zn excretion is the major source of Zn loss in the parenterally fed infant; factors causing increased zincuria will predispose the infant to Zn deficiency and affect the recommended Zn intake dosage. Histidine, threonine, and lysine have been shown to bind Zn increasing its renal ultrafilterability. The effect of the infusion of high and low lysine (206 +/- 34 vs 158 +/- 38 mg.kg-1.d-1; means +/- SD), threonine (147 +/- 24 vs 113 +/- 27), and histidine (124 +/- 34 vs 85 +/- 15) on urinary Zn excretion were determined in 23 newborns on TPN who received similar Zn intakes (6.8 +/- 1.4 mumol.kg-1.d-1). After a 72-h adaptation period each infant had urine collected for two 24-h periods. Despite the significant difference in amino acid intakes, mean urinary Zn excretion was identical (1.58 +/- 0.73 vs 1.56 +/- 0.63 mumol.kg-1.d-1). Hyperzincuria, therefore, does not occur when amino acids are infused at rates appropriate for the safety and nutritional maintenance of neonates.
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