Amino acid-mediated stimulation of renal phospholipid biosynthesis after acute tubular necrosis

Amino acid-mediated stimulation of renal phospholipid biosynthesis after acute tubular necrosis. The mechanism by which amino acid infusion stimulates membrane phospholipid biosynthesis during renal regeneration after mercuric-chloride-induced acute tubular necrosis was studied in the rat. Amino acids can act directly on regenerating renal tissue to enhance net phospholipid synthesis because preincubation of cortical slices with amino acids induced an increase in [14C]-choline incorporation into phospholipid without altering the rate of breakdown. This amino acid stimulation of phospholipid biosynthesis was studied further by measuring [14C]-choline accumulation and its sequential conversion to phosphorylcholine, cytidine diphosphocholine (CDP-choline), and phosphatidylcholine via the Kennedy pathway in regenerating renal tissue. [14C]-Choline accumulation was increased after amino acid infusion, compared to glucose infusion. There were also increments in the Vmax of the choline kinase reaction, which converts entering [14C]-choline into [14C]-phosphorylcholine, and of the cholinephosphotransferase reaction in which [14C]-CDP-choline is incorporated into [14C]-phosphatidylcholine, whereas the apparent Km of each reaction was unchanged. Thus, amino acids infused after tubular necrosis can act directly on regenerating renal cells to increase precursor availability and augment two reactions of the phospholipid bio-synthetic pathway.Stimulation par les acides aminés de la biosynthèse rénale de phospholipides après nécrose tubulaire aiguë. Le mécanisme par lequel la perfusion d'acides aminés stimule la biosynthèse de phospholipides membranaires au cours de la régénération rénale consécutive à la nécrose tubulaire aiguë déterminée par le chlorure mercurique a été étudié chez le rat. Les acides aminés peuvent agir directement sur le tissu rénal en régénération pour accroître la synthèse nette de phospholipides puisque la pré-incubation de tranches de cortex avec des acides aminés détermine une augmentation de l'incorporation de [14C]-choline dans les phospholipides sans modification du catabolisme. Cette stimulation par les acides aminés de la synthèse des phospholipides a été étudiée par la mesure de l'accumulation de [14C]-choline et de sa conversion séquentielle en phosphorylcholine, cytidine diphosphocholine (CDP-choline) et phosphatidylcholine, selon la voie de Kennedy, dans le tissu rénal en cours de régénération. L'accumulation de [14C]-choline est augmentée après perfusion d'acides aminés, par comparaison avec celle de glucose. On observe aussi des augmentations des Vmax de la réaction de la choline kinase, qui transforme la [14C]-choline entrante en [14C]-phosphorylcholine, et de la réaction de la cholinephosphotransferase, dans laquelle la [14C]-CDP-choline est incorporée dans la [14C]-phosphatidylcholine, alors que le Km de ces réactions est inchangé. Ainsi les acides aminés perfusés après une nécrose tubulaire peuvent agir directement sur les cellules rénales en régénération pour augmenter la disponibilité en précurseur et accélérer deux réactions de la voie de biosynthèse des phospholipides

The effects of whole milk compared to skim milk and apple juice consumption in breakfast on appetite and energy intake in obese children: a three-way randomized crossover clinical trial

Abstract Background A limited number of studies have examined the effect of dairy on satiety and short-term energy intake among children; furthermore we are not aware of any study comparing high and low-fat dairy products regarding their effect on appetite and short-term energy intake. Our objective was to assess the effect skim milk (SM) compared to whole milk (WM) and apple juice (AJ) on satiety and energy intake at lunch among 10–12 y children with obesity. Methods Fifty children with obesity who aged 10–12 y were randomized to consume a fixed content breakfast with 240 ml of SM, AJ, or WM for two consecutive days. The study was a three-way randomized crossover study; therefore each participant served as his/her own control. The total appetite, hunger, fullness, desire to eat and prospective consumption were measured using a visual analogue scale (VAS) before breakfast and every one hour after breakfast until a freely consumed lunch. VAS scores and energy intakes were compared using repeated measures procedure. Results Forty-eight participants (24 girls and 24 boys) completed the study. The energy intake was not different between SM, AJ and WM periods (adjusted mean ± standard error (SE) of energy intake: SM = 831.27 ± 30.64 Kcal, AJ = 794.92 ± 28.72 Kcal, WM = 798.87 ± 24.09 Kcal; P = 0.56). The effect was the same for either gender. Children reported higher satiety score 4 h after drinking WM with breakfast compared with SM (P < 0.05). The same association was found only in girls. Furthermore, SM significantly reduced appetite compared to AJ, 2 h after preloads in girls (P < 0.05). Conclusions Full-fat milk may have favorable effects on satiety but not energy intake in subsequent meal compared to skim milk among the children with obesity. Future studies with longer follow-up periods are needed to confirm these results. Trial registration The study protocol was registered with the Iranian registry of clinical trials on 9th October 2016 (registration ID: IRCT2016072012571N5)