ABSTRACT. Background. Peroxides have been reported to contaminate lipid emulsions and amino acid solutions used in total parenteral nutrition (TPN). This is particularly disturbing in newborn infants who are prone to several diseases related to immature defense mechanisms against oxidative challenges. It is not clear whether the antioxidants in multivitamins help protect parenteral nutrients against the hazards of oxidation.Objective. To evaluate the role of a multivitamin preparation (MVI) on the actual peroxide load received by patients on TPN.Methodology. The generation of peroxides in parenteral nutrition was tested first using test solutions. We compared the relative contribution of commercially available amino acid solutions, a lipid emulsion, and MVI on the level of peroxides in clinically relevant TPN solutions. Second, we measured the level of peroxides actually infused at the bedside. In both circumstances, the effects of time and light exposure were isolated. The level of peroxides was determined by a colorimetric technique and expressed as M equivalents tert-butyl hydroperoxide (M ‫؍‬ TBH).Results. Even when protected from light, the addition of MVI produced a 10-fold increase in peroxides (mean ؎ SEM, n ‫؍‬ 3, 19 ؎ 4 to 189 ؎ 8 M ‫؍‬ TBH at 4 h) in the fat-free TPN solution and a fourfold increase (64 ؎ 6 to 244 ؎ 8 M ‫؍‬ TBH at 4 h) in the lipid-containing TPN solution. A dose-response relationship was found between the concentration of MVI and peroxide levels. The effect of light was the strongest in the presence of multivitamins. The amino acid solutions had a relative inhibitory effect on the generation of peroxides by MVI, which varied (from 54 ؎ 1% to 72 ؎ 1%) all according to the amino acid blend. In parenterally fed premature infants, protecting the intravenous set from light decreased the load of infused peroxides (146 ؎ 15 vs 215 ؎ 24 M ‫؍‬ TBH).Conclusions. The lipid emulsion had a significant but minor additive effect compared with the multivitamin preparation, which was the major contributor to the generation of peroxides. Protection from photooxidation is not sufficient to prevent peroxidation of TPN solutions. Contrary to what one would expect, increasing the concentration of MVI will lead to a greater generation of peroxides, suggesting that the essential antioxidants in MVI do not have antiperoxide properties. Pediatrics 1997;99(3). URL: http://www.pediatrics.org/cgi/content/ full/99/3/e6; amino acids, antioxidants, detergents, lipids, newborn infants, oxidation, parenteral nutrition.ABBREVIATIONS. TPN, total parenteral nutrition; TBH, tert-butyl hydroperoxide; PN, fat-free and vitamin-free parenteral nutrition; MVI, multivitamin preparation.Isolated constituents of total parenteral nutrition (TPN) represent a potential source of oxidants. Because lipids infused with TPN solutions are contaminated by peroxides, 1,2 these emulsions are often believed to be the major source of oxidants in solutions of parenteral alimentation. However, other nutrients can promote peroxidation such as a...

Ghrelin has orexigenic effects. It is present in umbilical cord plasma in full-term neonates, raising the prospect that ghrelin plays a role in fetal and neonatal energy balance. We measured ghrelin in small (SGA), appropriate (AGA), and large (LGA) for gestational age neonates and evaluated whether ghrelin levels are modulated by neonatal insulin and glucose concentrations. Plasma concentrations of ghrelin, insulin, and glucose were measured in cord blood sampled at birth in 123 SGA, AGA, and LGA neonates (gestational age, 24-41 wk) born to mothers with and without diabetes. Ghrelin was detected in samples from all infants. Its concentration was 40% higher in SGA neonates (mean +/- SD, 2436 +/- 657 pg/ml) compared with AGA (1738 +/- 380) and LGA (1723 +/- 269) neonates. There was a positive correlation between ghrelin and gestational age in AGA/LGA (r = 0.23; P < 0.05) and a negative correlation in SGA (r = -0.67; P < 0.005) neonates. Therefore, the difference in ghrelin between SGA and AGA/LGA neonates decreases with advancing gestational age. Birth weight z-score, maternal hypertension, and glucose concentrations were significant determinants of ghrelin concentrations. In conclusion, SGA neonates present with higher umbilical cord ghrelin plasma concentrations than AGA/LGA neonates. Ghrelin may play a physiological role in fetal adaptation to intrauterine malnutrition.

In vitro, bilirubin is a strong antioxidant, but in vivo its capacity to act as a scavenger of toxic oxygen radicals remains poorly documented. The aim of this study was to evaluate if bilirubin had antioxidant properties in jaundiced infants. The antioxidant capacity of neonatal plasma was measured in Trolox equivalents (TEAC, mmol/l) and correlated in vitro with plasma bilirubin concentrations (r² = 0.99). Plasma TEAC was compared before and after exchange transfusions for neonatal hyperbilirubinemia (250–435 μmol/l). The antioxidant properties of the paired blood samples before and after exchange transfusions (TEAC: 1.67 ± 0.12 vs. 1.37 ± 0.09 mmol/l, n = 11) varied in proportion to the serum bilirubin levels. The changes in other antioxidants were not large enough to account for the magnitude of change in antioxidant capacity. Therefore, in vivo, the plasma antioxidant capacity of jaundiced newborn infants is related to the level of bilirubin.

In the presence of light, a multivitamin preparation is the main source of peroxides in solutions of total parenteral nutrition (TPN). This preparation contains two photosensitive products, 5'-phosphate flavin mononucleotide (FMN) and polysorbates (PS), as well as electron donors such as ascorbate (AH). We hypothesized that the admixture of FMN or PS with electron donors generates peroxides in TPN and alters the quality of nutrients. Using xylenol orange, peroxide concentrations were measured in solutions containing AH, FMN, and/or PS in water, a dextrose solution, an amino acid preparation, and a lipid emulsion. Thiol functions were evaluated by reduction of 5,5-dithiobis(2-nitrobenzoic acid) in the amino acid preparation. After 24-h light exposure, dextrose solutions with admixtures of AH + FMN or AH + FMN + PS generated peroxides at concentrations similar to those observed in a 1% multivitamin solution, and over three times higher than those observed with FMN, PS, or AH alone. However, in the presence of amino acids, FMN alone induced a generation of peroxides comparable to that observed with FMN + AH. In the lipid emulsion, peroxides increased over 3-fold in the presence of FMN or FMN + AH. The addition of catalase suggested that lipid peroxides and H2O2 were produced, and the loss of thiol function suggested that an oxidation of amino acids occurred. When exposed to light, FMN induces reactions with amino acids, polyunsaturated fatty acids, and even AH, altering the quality of nutrients. Paradoxically, AH without FMN has a protective effect on peroxide generation in TPN.