Dietary threonine reduces plasma phenylalanine levels in patients with hyperphenylalaninemia.

BACKGROUND: In order to achieve normal intellectual development, the plasma phe-nylalanine (PHE) levels of patients with hyperphenylalaninemia should not exceed toxic levels. This goal is usually accomplished by employing special diets in which the patient's protein intake is in the form of PHE-free mixtures of amino acids. There is evidence from our own observations in animals and a preliminary observation in patients with hyperphenylalaninemia that supplemental dietary threonine (THR) might decrease plasma PHE concentrations. METHODS: In this placebo-controlled crossover study, the effect of supplemental oral THR on the plasma amino acid concentrations of 12 patients with hyperphenylalaninemia was investigated. Before starting the first treatment period of this cross-over study, the patients were randomly assigned to one of two groups supplemented either with approximately 50 mg THR/kg per day or with a similar amount of maltodextrin as placebo. After a feeding period of 8 weeks and a wash-out period of 8 weeks, the supplements were crossed over and the study continued for an additional 8 weeks. Blood was obtained at the start and the end of each supplementation period. RESULTS: Dietary THR supplementation of approximately 50 mg/kg per day resulted in a significant decrease of plasma PHE levels ( P = 0.0234). There was a close positive correlation between plasma and urinary PHE concentrations ( P < 0.001) indicating that the lower plasma PHE levels in the THR supplemented patients were not caused by higher urinary excretion of PHE. CONCLUSIONS: The data of the present study show that oral THR supplementation has a clear plasma-PHE-reducing effect but they do not allow any conclusion about the mechanisms responsible for the observed effect. Although it seems attractive on the basis of the present data to use THR supplementation in patients with hyperphenylalaninemia, the mechanism of the observed effect should be clarified before introduction of such a treatment in these patients.

[Tissue antioxidant capacity and bacterial translocation in parenteral nutrition. Experimental study]. / Capacidad antioxidante tisular y traslocación bacteriana bajo nutrición parenteral. Estudio experimental.

Alterations in the antioxidant system (AS) has been observed during total parenteral nutrition (TPN). Light exposure or changes in the composition of TPN may affect this deleterious effect. On the other hand, bacterial translocation (BT) is frequent under TPN and may be related to AS. The aim of the study was to determine the adverse effect of standard and glutamine-enriched (GE) TPN, with or without light exposure, on the AS, and its relationship to BT. Forty-nine adult Wistar rats underwent central venous cannulation and were randomly assigned to one of five groups: Sham (n = 16): chow and water ad libitum and saline i.v. TPN (n = 10): had standard TPN. TPN(-) (n = 8): standard TPN without light-exposure. GTPN (n = 8): GE TPN. GTPN(-) (n = 7): GE TPN without light exposure. After 10 days, glutation reduced (GSH) was determined in liver and kidney. Mesenteric lymph nodes, peripheral and portal blood samples were cultured for BT. Comparing to Sham rats, TPN groups had statistically significant lower GSH levels, but there were no differences between standard or GE groups nor with or without light exposure groups. Sham animals had 12% BT. Significantly higher BT (p < 0.05) was found in TPN rats: 70% in TPN group, 88% in TPN(-) group, 86% in GTPN(-) animals and only 50% in GTPN group (p = 0.06 vs TPN group). To conclude: 1. TPN reduces antioxidant capacity and induces BT. 2. Glutamine supplementation or light protection do not improve tissue antioxidant capacity under TPN. 3. Glutamine supplementation tends to reduce BT only in the presence of light. 4. Absence of light exposure does not improve BT TPN-related.

Capacidad antioxidante tisular y traslocación bacteriana bajo nutrición parenteral. Estudio experimental / Tissue antioxidant capacity and bacterial translocation under total parenteral nutrition. An experimental study

Durante la nutrición parenteral total (NPT) aparecen alteraciones en la capacidad antioxidante (CA) que pueden depender de la propia NPT o de su exposición a la luz. La traslocación bacteriana (TB) es frecuente bajo NPT y puede estar relacionada con la CA. Se ha estudiado el efecto adverso de la NPT estándar o suplementada con glutamina (SG), con o sin exposición a la luz, sobre la CA, y su relación con la TB. Tras colocar un catéter central a 49 ratas Wistar adultas, se les randomizó para uno de los cinco grupos siguientes:* Sham (n = 16): suero salino.i.v. y dieta oral libre.* NPT (n = 10): NPT estándar expuesta a la luz.* NPT(-) (n = 8): NPT estándar sin exposición a la luz.* GNPT (n = 8): NPT expuesta a la luz y SG.* GTPN(-) (n = 7): NPT sin exposición a la luz y SG.A los diez días se determinó el glutation reducido (GSH) en hígado y riñón y se cultivaron ganglio mesentérico y sangre portal y periférica. Los grupos con NPT tuvieron niveles significativamente más bajos de GSH que el grupo Sham, pero no hubo diferencias entre los grupos con NPT estándar o, ni entre grupos con y sin exposición a la luz. En el grupo Sham la TB fue del 12 por ciento, mientras que en los que recibieron NPT fue mayor (p < 0,05): 70 por ciento en el grupo NPT, 88 por ciento en el NPT(-), 86 por ciento en el GNPT(-) y sólo 50 por ciento en el grupo GNPT (p = 0,06 vs grupo NPT).En conclusión: 1. La NPT disminuye la CA e induce TB. 2. El SG o la protección contra la luz no mejoran la CA tisular bajo NPT: 3. La ausencia de luz no disminuye la TB debida a la NPT. 4. El SG reduce la TB sólo en presencia de luz (AU)

Tissue antioxidant capacity and bacterial translocation under total parenteral nutrition.

Alterations in the antioxidative system have been observed during total parenteral nutrition (TPN). Light exposure or changes in the composition of TPN formulas may affect this system. Bacterial translocation (BT) is frequent under TPN and may be related to oxidative status. The aim of this study was to determine the adverse effects of standard and glutamine-enriched TPN, with or without light exposure, on oxidative status (liver and kidney-reduced glutathione, GSH) and its relationship to BT. Thirty-three adult Wistar rats underwent central-venous cannulation and were randomly assigned to one of four groups receiving different TPN regimes for 10 days. The TPN group (n = 10) had standard TPN, the TPN(-) group (n = 8) standard TPN without light exposure, the GTPN group (n = 8) glutamine-enriched TPN, and the GTPN(-) group (n = 7) glutamine-enriched TPN without light exposure. A sham group (n = 16) receiving chow and water ad libitum and saline i.v. served as controls. At the end of the experiment, GSH was determined in liver and kidney tissue. Mesenteric lymph nodes and peripheral and portal blood samples were cultured for BT. Compared to sham rats, TPN groups had statistically significant lower GSH levels, but there were no differences between standard or glutamine-enriched groups or light-exposure groups. Sham animals had 12% BT. Significantly higher BT (P < 0.05) occurred in TPN rats: 70% in the TPN group, 88% in the TPN(-) group, 86% in GTPN (-) animals, and only 50% in the GTPN group (P = 0.06 vs TPN group). In conclusion, (1) TPN reduces antioxidant capacity; (2) glutamine supplementation or light protection does not improve tissue antioxidant capacity under TPN; (3) the absence of light exposure does not improve TPN-related BT; and (4) glutamine supplementation tends to reduce BT only in the presence of light.