S. Nakib

Napping Reverses the Salivary Interleukin-6 and Urinary Norepinephrine Changes Induced by Sleep Restriction

CONTEXT Neuroendocrine and immune stresses imposed by chronic sleep restriction are known to be involved in the harmful cardiovascular effects associated with poor sleep. OBJECTIVES Despite a well-known beneficial effect of napping on alertness, its effects on neuroendocrine stress and immune responses after sleep restriction are largely unknown. DESIGN This study was a strictly controlled (sleep-wake status, light environment, caloric intake), crossover, randomized design in continuously polysomnography-monitored subjects. SETTING The study was conducted in a laboratory-based study. PARTICIPANTS The subjects were 11 healthy young men. INTERVENTION We investigated the effects on neuroendocrine and immune biomarkers of a night of sleep restricted to 2 h followed by a day without naps or with 30 minute morning and afternoon naps, both conditions followed by an ad libitum recovery night starting at 20:00. MAIN OUTCOME MEASURES Salivary interleukin-6 and urinary catecholamines were assessed throughout the daytime study periods. RESULTS The increase in norepinephrine values seen at the end of the afternoon after the sleep-restricted night was not present when the subjects had the opportunity to take naps. Interleukin-6 changes observed after sleep deprivation were also normalized after napping. During the recovery day in the no-nap condition, there were increased levels of afternoon epinephrine and dopamine, which was not the case in the nap condition. A recovery night after napping was associated with a reduced amount of slow-wave sleep compared to after the no-nap condition. CONCLUSIONS Our data suggest that napping has stress-releasing and immune effects. Napping could be easily applied in real settings as a countermeasure to the detrimental health consequences of sleep debt.

Effect of apoE/ATP-containing liposomes on hepatic energy state

Background/Aims: ATP‐containing liposomes partially prevent ATP depletion in the cold‐stored liver. As hepatocytes can specifically bind apoE, we investigated whether the addition of apoE to large (200 nm) ATP‐containing liposomes increases their uptake by the liver and further improves hepatic energy stores.

Citrulline decreases hepatic endotoxin-induced injury in fructose-induced non-alcoholic liver disease: an ex vivo study in the isolated perfused rat liver

Steatosis can sensitise the liver to various challenges and favour the development of non-alcoholic fatty liver disease (NAFLD). In this context, fructose feeding promotes endotoxin translocation from the gut, contributing to disease progression via an inflammatory process. Citrulline is protective against fructose-induced NAFLD; we hypothesised that this property might be related to its anti-inflammatory and antioxidative action against endotoxin-induced hepatic injuries. This hypothesis was evaluated in a model of perfused liver isolated from NAFLD rats. Male Sprague-Dawley rats (n 30) were fed either a standard rodent chow or a 60 % fructose diet alone, or supplemented with citrulline (1 g/kg per d) for 4 weeks. After an evaluation of their metabolic status, fasted rats received an intraperitoneal injection of lipopolysaccharide (LPS) (2·5 mg/kg). After 1 h, the livers were isolated and perfused for 1 h to study liver function and metabolism, inflammation and oxidative status. In vivo, citrulline significantly decreased dyslipidaemia induced by a high-fructose diet and insulin resistance. In the isolated perfused rat livers, endotoxaemia resulted in higher cytolysis (alanine aminotransferase release) and higher inflammation (Toll-like receptor 4) in livers of fructose-fed rats, and it was prevented by citrulline supplementation. Oxidative stress and antioxidative defences were similar in all three groups. Amino acid exchanges and metabolism (ammonia and urea release) were only slightly different between the three groups. In this context of mild steatosis, our results suggest that fructose-induced NAFLD leads to an increased hepatic sensitivity to LPS-induced inflammation. Citrulline-induced restriction of the inflammatory process may thus contribute to the prevention of NAFLD.

N-Carbamoylputrescine, a citrulline-derived polyamine, is not a significant citrulline metabolite in rats.

Citrulline, a key amino acid of the urea cycle, has been shown to play a regulatory role in protein and energy metabolism in mammals. We questioned whether N-carbamoyl-putrescine (NCP), the decarboxylated derivative of citrulline, could play a role in the biological properties of this amino acid. To evidence the presence of NCP in mammalian tissues, we developed a sensitive reverse-phase high-performance liquid chromatography (HPLC) with fluorimetric detection method with precolumn dansyl derivatization and solid-phase extraction for the determination of NCP together with polyamines in biological samples. Dansyl NCP was identified with a 5.85-min retention time. Linearity was obtained in a concentration range of 0.125 to 12.5 μM. Intraday and day-to-day relative coefficients of variation ranged from 8.9% to 12.3% and from 14% to 14.3%, respectively. Recovery rates in serum ranged from 75% to 83%. Thereafter, we used this method to search for the presence of NCP in serum, muscle, liver, jejunum, and ileum in rats after both short-term intraperitoneal injection and long-term oral citrulline supplementation. We failed to detect NCP in these animals. These data suggest that NCP is not a significant citrulline metabolite in rats.

O021 Méthode simple et rapide pour le dosage simultané des vitamines A et E dans les mélanges polymériques pour nutrition entérale

Introduction et but de l’etude Dans les melanges polymeriques destines a la nutrition enterale (MPE), les vitamines liposolubles sont presentes sous forme de differents esters. Le dosage du contenu total en ces vitamines necessite de les liberer de ces liaisons esters par une premiere etape de saponification, etape delicate du fait de la sensibilite de ces molecules a l’oxydation. Les methodes existantes sont peu sensibles, fastidieuses, couteuses et peu adaptees a une utilisation en routine. Le but de cette etude a ete de developper une methode simple et rapide pour doser simultanement les vitamines A et E dans les MPE. Materiel et methodes Apres optimisation des etapes de saponification et d’extraction, la procedure analytique suivante a ete retenue. A 100 μl de MPE (Sondalis ® Iso, Nestle Clinical Nutrition) sont ajoutes 50 |il d’un etalon interne (Tocol 64 |JM). L’echantillon est ensuite deproteinise par addition de 900 μl d’ethanol absolu contenant 1 % de pyrogallol (antioxydant) et saponifie par 200 μl d’une solution de KOH (3,6 M) dans un sonicateur (Branson 2210), 30 min a 65°C et sous atmosphere d’azote. Les echantillons sont alors tamponnes par 500 μl de NaH2PO4 (0,2 M, pH 7,8) et une double extraction a l’hexane est realisee. La separation et la quantification des vitamines sont realisees par chromatographie liquide haute performance en phase inverse (colonne DiscoveryTM C8, 25 cm × 4,6 mm, 5 μm) (avec une phase mobile methanol-acetonitrile-eau 75/15/10, v/v) et une detection spectrophotometrique a deux longueurs d’onde (292 et 325 nm). La linearite, la repetabilite (n = 10) et la reproductibilite (n = 20 en 4 series) ont ete determinees et leurs coefficients de variation (CV) ont ete calcules. Resultats Les temps de retention des vitamines A et E sont respectivement de 5,7 et 14,1 min. Les parametres de validation sont les suivants : Tableau 1 Vit A Vit A Vit E Vit E Linearite min : 0,2 μ M max : 10,0 μ M min : 3,0 μ M max : 84,4 μ M Repetabilite 4,7 ± 0,2 μ M CV : 4,0 % 30,6 ±1,5 μ M CV: 4,9 % Reproductibilite 5,2 ± 0,3 μ M CV : 4,7 % 27,2 ± 1,4 μ M CV: 5,0 % Conclusions Cette procedure validee est bien adaptee en termes de sensibilite. Elle est simple a realiser, peu couteuse et applicable en routine.