L-Leucine

BACKGROUND: Pressure ulcers are localized injuries to the skin or the underlying tissue, or both, and are common in older and immobile people, people with diabetes, vascular disease, or malnutrition, as well as those who require intensive or palliative care. People with pressure ulcers often suffer from severe pain and exhibit social avoidance behaviours. The prevention and treatment of pressure ulcers involves strategies to optimize hydration, circulation, and nutrition. Adequate nutrient intake can reduce the risk factor of malnutrition and promote wound healing in existing pressure ulcers. However, it is unclear which nutrients help prevent and treat pressure ulcers. This is an update of an earlier Cochrane Review. OBJECTIVES: To evaluate the benefits and harms of nutritional interventions (special diets, supplements) for preventing and treating pressure ulcers in people with or without existing pressure ulcers compared to standard diet or other nutritional interventions. SEARCH METHODS: We used extensive Cochrane search methods. The latest search was in May 2022. SELECTION CRITERIA: We included randomized controlled trials (RCTs) in people with or without existing pressure ulcers, that compared nutritional interventions aimed at preventing or treating pressure ulcers with standard diet or other types of nutritional interventions. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcome for prevention studies was the proportion of participants who developed new (incident) pressure ulcers. For treatment studies, our primary outcomes were time to complete pressure ulcer healing, number of people with healed pressure ulcers, size and depth of pressure ulcers, and rate of pressure ulcer healing. Secondary outcomes were side effects, costs, health-related quality of life and acceptability. We used GRADE to assess certainty of evidence for each outcome. MAIN RESULTS: We included 33 RCTs with 7920 participants. Data for meta-analysis were available from 6993 participants. Pressure ulcer prevention Eleven studies (with 12 arms) compared six types of nutritional interventions for the prevention of pressure ulcers. Compared to standard diet,

OBJECTIVES: Our objective was to evaluate the acute effect of L-leucine supplementation and high-intensity sprint exercise on appetite-controlling neuropeptides and their association with the subjective perception of appetite (SPA), satiety (SPS), food intake, and inflammatory response in overweight participants. METHODS: In a double-masked, randomized, counterbalanced, and crossover design, 12 sedentary overweight adult men performed four experiments: (1) exercise and L-leucine (EX-Leu), (2) exercise and placebo (EX-PLA), (3) L-leucine without exercise (SED-Leu), and (4) placebo without exercise (SED-PLA). The supplementation consisted of three daily doses of 70 mg/kg body weight of L-leucine or placebo (on the day of exercise and one day after). During the experiments, we recorded the food intake, SPA, and SPS, and evaluated the neuropeptides (GLP-1, PYY, CCK, and ghrelin) and cytokines (IL1-beta, IL-6, IL-10, and TNF-α) in peripheral blood. The acute exercise trial consisted of four sets of 30 sec cycle ergometer sprint exercises. RESULTS: EX-Leu, EX-PLA, and SED-Leu decreased SPA, compared to SED-PLA; only EX-PLA improved SPS; EX-PLA and EX-Leu reduced food intake. GLP-1 decreased in the EX-PLA trial compared to SED-Leu. IL-6 and IL1-β levels increased in the EX-Leu trial compared to SED-PLA. An anti-inflammatory profile was identified in the EX-PLA trial compared to the other trials. Both neuropeptides (increased) and cytokines (a pro-inflammatory profile) were associated with changes in SPA, SPS, and food intake. CONCLUSIONS: The acute inflammatory balance induced by EX-Leu seems to improve appetite control. Sprint exercise had a consistent acute anorexic effect, while isolated L-leucine decreased SPA, but their impact on SPS and food intake is not clear (FAPESP grants: 2020/09936-2 and 2021/03601-1).

BACKGROUND: The amino acids, L-leucine (Leu) and L-isoleucine (Ile), and the bitter substance, quinine, reduce postprandial glucose, stimulate insulin, and/or slow gastric emptying. Whether combining these stimuli can enhance these effects is not known. OBJECTIVES: We investigated whether combined intragastric administration of quinine with Leu or Ile, each in submaximal dose, would reduce the plasma glucose response to a mixed-nutrient drink more than each compound individually, associated with greater insulin stimulation and/or slowing of gastric emptying. METHODS: Fifteen healthy, lean males were recruited for each of the 2 study parts. They received on 4 separate occasions, 1) 300 mg quinine hydrochloride ("QHCl"), 2) 5g ("Leu"; part A) or 5g ("Ile"; part B), 3) combination of 1) + 2) ("QHCl + Leu" or "QHCl + Ile"), or 4) control intragastrically, in a randomized, double-blind fashion. At t = -60 min, either QHCl or control was administered, and 30 min later (at t = -30 min), amino acid or control was administered. At t = -1 min, participants consumed a mixed-nutrient drink labeled with sodium acetate-1-13C for measurement of gastric emptying by breath test. Plasma glucose and insulin were measured at baseline (i.e. t = -60 min), for 60 min before the drink, and for 180 min postdrink. Breath samples were collected at baseline and postdrink, for subsequent analysis of 13CO2. RESULTS: QHCl, QHCl + Leu, and QHCl + Ile delayed the early rise in plasma glucose compared with control, Leu, and Ile (all P < 0.05). QHCl + Leu and QHCl + Ile stimulated insulin compared with QHCl, Leu, and control (all P < 0.05), but did not affect gastric emptying. The early glucose response [area under the curve (AUC), t = 0‒30 min (AUC0‒30 min)] was related directly to early gastric emptying (AUC0‒30 min) (R > 0.41, P < 0.01). CONCLUSIONS: In healthy males, although combining QHCl with Leu or Ile, in the doses used, did not enhance their glucose-lowering effects, even small changes in the early gastric emptying rate and insulin stimulation appear to contribute to postprandial glucose-lowering. This trial was registered at clinicaltrials.gov as NCT05720390 and NCT05682339.

Comment in doi: 10.1212/WNL.0000000000213857. Comment in Neurology. 105:e213857. BACKGROUND AND OBJECTIVES: N-acetyl-l-leucine (NALL) has been established to improve the neurologic manifestations of Niemann-Pick disease type C (NPC) after 12 weeks in a placebo-controlled trial. In the open-label extension phase (EP) follow-up, data were obtained after 12 and 18 months to evaluate the long-term effects of NALL for NPC. METHODS: This is an ongoing, multinational, multicenter EP. Patients with a genetic diagnosis of NPC aged 4 years or older who completed the placebo-controlled trial were eligible to continue in the EP and receive orally administered NALL 2-3 times per day in 3 tiers of weight-based dosing. The primary end point is the modified 5-domain NPC Clinical Severity Scale (NPC-CSS) (range 0-25 points; lower score representing better neurologic status); data from the EP cohort are compared with the expected annual trajectory of decline (i.e., disease progression) established in natural history studies. Analyses are also performed on exploratory end points, including the 15-domain and 4-domain NPC-CSSs and the Scale for Assessment and Rating of Ataxia (SARA). RESULTS: Fifty-three patients aged 5-67 years (45.3% female, 54.7% male) were enrolled in the EP. After 12 months, the mean (±SD) change from baseline on the 5-domain NPC-CSS was -0.27 (±2.42) with NALL vs +1.5 (±3.16) in the historical cohort (95% CI -3.05 to -0.48; p = 0.009), corresponding to a 118% reduction in annual disease progression. After 18 months, the mean (±SD) change was +0.05 (±2.95) with NALL vs +2.25 (±4.74) in the historical cohort (95% CI -4.06 to -0.35; p = 0.023). The 15-domain and 4-domain NPC-CSSs were consistent with the 5-domain NPC-CSS. The improvements in neurologic manifestations demonstrated in the placebo-controlled trial on the primary SARA end point were sustained over the long-term follow-up. NALL was well tolerated, and no treatment-related adverse events or serious reactions occurred. DISCUSSION: Treatment with NALL was associated with a significant reduction in NPC disease progression after 12 and 18 months, demonstrating a disease-modifying, neuroprotective effect.

BACKGROUND: L-tryptophan ("Trp") and L-leucine ("Leu"), when administered intraduodenally, increase plasma cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) and stimulate pyloric pressures, which all slow gastric emptying and suppress subsequent energy intake. The circulating Trp-to-large-neutral-amino-acids ("Trp/LNAAs") ratio is also inversely related to energy intake. OBJECTIVES: This exploratory study characterized the impact of standardized changes in the plasma Trp/LNAAs ratio, achieved by combining a fixed-load intraduodenal infusion of Trp with increasing loads of Leu, on the appetite-inhibitory effects of enteral Trp. METHODS: Twelve males of normal weight [mean ± standard deviation; age: 23 ± 2 y; body mass index (in kg/m2: 23±1)], received on 4 separate occasions, 90-min iso-osmotic intraduodenal infusions of 1) isotonic 0.9% saline ("control"), 2) Trp (0.15 kcal/min; "Trp"), 3) Trp + Leu (0.22 kcal/min; "Trp+Leu-0.22"), or 4) Trp + Leu (0.45 kcal/min; "Trp+Leu-0.45"), in a randomized, double-blind, cross-over fashion. Immediately postinfusion ad-libitum energy intake was quantified. Plasma CCK, GLP-1, amino acid concentrations, and antropyloroduodenal pressures were measured throughout. RESULTS: Although there was a transient stimulation of CCK and GLP-1 by Trp + Leu - 0.45 (at t = 15 min), only Trp led to a sustained increase in plasma CCK (P = 0.04) and GLP-1 (P = 0.009) from t = 60-90 min, and stimulated pyloric pressures (P = 0.01), compared with control. Only Trp reduced energy intake [kcal (mean ± standard error of the mean); control: 1085 ± 49, Trp: 881 ± 75, Trp + Leu - 0.22: 963 ± 57, Trp + Leu - 0.45: 932 ± 60] compared with control (P = 0.008). The Trp/LNAAs ratio was dose-dependently decreased by Trp + Leu - 0.22 and Trp + Leu - 0.45, compared with Trp (all P = 0.001), and energy intake correlated inversely with the Trp/LNAAs ratio (R = -0.38; P = 0.02). CONCLUSIONS: Acute reduction in the Trp/LNAAs ratio appears to be associated with a diminished capacity of Trp to stimulate CCK and GLP-1 and suppress energy intake. Although these observations should be interpreted with caution given the exploratory nature of the study, they atte

BACKGROUND: Ataxia telangiectasia (AT) is an autosomal recessive multisystem disorder. Most patients have progressive cerebellar ataxia, oculocutaneous telangiectasia, frequent pulmonary infection, and an increased risk of malignancies. Although N-acetyl-dl-leucine (ADLL) has shown some efficacy in patients with AT, its more pharmacologically active enantiomer, N-acetyl-l-leucine (NALL), has just recently been investigated in ataxic individuals. The current study assessed the efficacy of NALL in patients with AT. METHODS: This 2 × 2 crossover, double-blind, randomized clinical trial was conducted on 20 patients with AT. After excluding four patients, 16 subjects (eight females, eight males; mean age 9.8 ± 3.5 years) with a definitive genetic diagnosis of AT were randomly assigned to one of two study groups, with one group receiving 1-4 g/day NALL or a placebo for six weeks. Subjects then had a 4-week washout before crossing over to the other treatment for an additional six weeks. The Spinocerebellar Ataxia Functional Index (SCAFI) and the Scale for Assessment and Rating of Ataxia (SARA) score assessed patients' motor function. Quality of life (QOL) was evaluated by a specialist using the PedsQL questionnaire. Fasting blood samples were taken from all subjects before and after each intervention to determine potential side effects. RESULTS: Although patients' nausea and constipation were improved, the results failed to reveal any significant benefits of NALL treatment on ataxia symptoms. NALL treatment had no significant effects on SARA, SCAFI-9HPT (9-hole peg test) nondominant, SCAFI-9HPT dominant, or SCAFI-8WMT (8 m walking time) (p > 0.05). Our patient's Physical Health score in Child self-report and Parent proxy-report did not significantly change in the treatment group compared to the placebo (p > 0.05). Furthermore, there were no significant changes in energy and macronutrient intake after NALL treatment. None of the volunteers reported serious or moderate side effects. CONCLUSIONS: To the best of our knowledge, this was the first placebo-controlled, randomized clinical trial exploring NALL's potential effects for treating AT. Despite improvements in some sy

BACKGROUND: Niemann-Pick disease type C is a rare lysosomal storage disorder. We evaluated the safety and efficacy of N-acetyl-l-leucine (NALL), an agent that potentially ameliorates lysosomal and metabolic dysfunction, for the treatment of Niemann-Pick disease type C. METHODS: In this double-blind, placebo-controlled, crossover trial, we randomly assigned patients 4 years of age or older with genetically confirmed Niemann-Pick disease type C in a 1:1 ratio to receive NALL for 12 weeks, followed by placebo for 12 weeks, or to receive placebo for 12 weeks, followed by NALL for 12 weeks. NALL or matching placebo was administered orally two to three times per day, with patients 4 to 12 years of age receiving weight-based doses (2 to 4 g per day) and those 13 years of age or older receiving a dose of 4 g per day. The primary end point was the total score on the Scale for the Assessment and Rating of Ataxia (SARA; range, 0 to 40, with lower scores indicating better neurologic status). Secondary end points included scores on the Clinical Global Impression of Improvement, the Spinocerebellar Ataxia Functional Index, and the Modified Disability Rating Scale. Crossover data from the two 12-week periods in each group were included in the comparisons of NALL with placebo. RESULTS: A total of 60 patients 5 to 67 years of age were enrolled. The mean baseline SARA total scores used in the primary analysis were 15.88 before receipt of the first dose of NALL (60 patients) and 15.68 before receipt of the first dose of placebo (59 patients; 1 patient never received placebo). The mean (±SD) change from baseline in the SARA total score was -1.97±2.43 points after 12 weeks of receiving NALL and -0.60±2.39 points after 12 weeks of receiving placebo (least-squares mean difference, -1.28 points; 95% confidence interval, -1.91 to -0.65; P<0.001). The results for the secondary end points were generally supportive of the findings in the primary analysis, but these were not adjusted for multiple comparisons. The incidence of adverse events was similar with NALL and placebo, and no treatment-related serious adverse events occurred. CONCLUSIONS: Among patients with Niemann-Pick disease type

BACKGROUND: Malnutrition and metabolic alterations of cancer cachexia are often associated with negative weight loss and muscle mass wasting. In this sense, protein supplementation can be a strategy to help counteract the loss and/or maintenance of mass in these patients. The aim of this study was to evaluate the effect of leucine supplementation on body composition in outpatients with gastrointestinal tract cancer. METHODS: It was a randomized, blinded, controlled, parallel trial, performed in male patients with a cancer diagnosis of the gastrointestinal tract and appendix organs undergoing chemotherapy. All the patients were allocated to one of the protocol groups: L-leucine supplement or the control group, during 8 weeks of intervention. We evaluated the body composition through bioelectrical impedance analysis, the cancer cachexia classification, and the diet intake before and after the intervention protocol. The intention-to-treat approach was performed to predict the missing values for all patients who provide any observation data. RESULTS: The patients were an average age of 65.11 ± 7.50 years old. In the body composition analysis with patients who finished all the supplementation, we observed a significant gain in body weight (61.79.9 ± 9.02 versus 64.06 ± 9.45, p = 0.01), ASMM (7.64 ± 1.24 versus 7.81 ± 1.20, p = 0.02) in the Leucine group, whereas patients in the control did not present significant variation in these parameters. There was no significant intergroup difference. While in the analysis included the patients with intention-to-treat, we found a significant increase in body weight (p = 0.01), BMI (p = 0.01), FFM (p = 0.03), and ASMM (p = 0.01) in the Leucine group. No significant intergroup differences. These results also similar among cachectic patients. CONCLUSION: A balanced diet enriched with free-Leucine supplementation was able to promotes gains in body weight and lean mass in older men diagnosticated with gastrointestinal and appendix organs of digestion cancer after 8 weeks. However, the fact that most men are non-cachectic or pre-cachectic is not clear if the increase in muscle mass was due to a high intake of leucine, since no differ

Chapman-Lopez, TJ, Funderburk, LK, Heileson, JL, Wilburn, DT, Koutakis, P, Gallucci, AR, and Forsse, JS. Effects of L-leucine supplementation and resistance training on adipokine markers in untrained perimenopausal and postmenopausal women. J Strength Cond Res 38(3): 526-532, 2024-This study examined the effects of supplementing 5 g of leucine compared with a placebo during a 10-week resistance training program on body composition parameters and adipokine concentrations in untrained, perimenopausal and postmenopausal women. Thirty-five women were randomly assigned to 2 groups-leucine (LEU, n = 17) and placebo (PLC, n = 18)-in a double-blind, placebo-controlled trial. Each group consumed the supplement or placebo every day and completed a resistance training program for 10 weeks. Using 3-day food records, a diet was assessed before the intervention and after its cessation. Body composition was assessed preintervention and postintervention using dual-energy x-ray absorptiometry. Moreover, the concentrations of adipokines, such as adiponectin, visfatin, leptin, and monocyte chemoattractant protein-1 (MCP-1), were assessed preintervention and postintervention. Both groups showed an increase in visceral adipose tissue (VAT) area ( p = 0.030) and fat-free mass (FFM; p = 0.023). There were significant group differences in concentrations of visfatin ( p = 0.020) and leptin ( p = 0.038) between the PLC and LEU groups. Visfatin displayed higher concentrations in the PLC group and leptin displayed higher concentrations in the LEU group. In addition, there were significant decreases in adiponectin concentrations for both groups (LEU: 652 ± 513 to 292 ± 447 pg·ml -1 ; PLC: 584 ± 572 to 245 ± 356 pg·ml -1 , p = 0.002) and MCP-1 only decreased in the PLC group (253 ± 119 to 206 ± 106 pg·ml -1 , p = 0.004). There were significant decreases in adiponectin concentrations in both groups and a decrease in MCP-1 concentrations in the PLC group. These decreases may be due to both adipokines possible relationship with VAT area. However, it is not known whether leucine has underlying properties that hinder changes in MCP-1 concentrations.

BACKGROUND: L-Leucine (Leu) supplementation may benefit fat-free mass (FFM) per se and glucose metabolism. OBJECTIVES: To determine whether Leu supplementation during energy restriction blunted the loss of FFM, enhanced the loss of fat mass (FM) and improved glucose tolerance. DESIGN: Thirty-seven adults, aged 20-65 years, with increased waist circumference and at least one other metabolic syndrome (MetS) component, were selected. We employed a two-arm parallel, double blind, randomized control trial (RCT) design. Participants were randomly assigned to an intervention group (leucine - 3 g/d) or placebo (lactose - 2.67 g/d), while following an individualised energy restricted diet for an 8-week period. Detailed body composition (DEXA), oral glucose tolerance test (OGTT), insulin and components of MetS were measured before and after the trial. Analysis of covariance (ANCOVA) assessed the effect of Leu on an intention-to-treat (ITT) principle. Bootstrapping method with 1000 bootstrap samples was used to derive parameter estimates, standard errors, p-values, and 95% confidence intervals for all outcomes. RESULTS: Adjusted for baseline values and other covariates, FFM (p = 0.045) and lean tissue mass (LTM) (p = 0.050) were significantly higher following Leu. These outcomes were modified by a significant treatment x sex interaction that indicated Leu had the greater effect in men. However, on adjustment for body composition changes, there was no difference in insulin sensitivity, oral glucose tolerance, or change in MetS components following Leu. CONCLUSION: Short-term leucine supplementation during energy restriction resulted in a greater preservation of FFM and LTM particularly in men, but did not impact glucose metabolism. © 2023. The Author(s).

BACKGROUND: Niemann-Pick disease type C (NPC) is a rare autosomal recessive neurodegenerative lysosomal disease characterized by multiple symptoms such as progressive cerebellar ataxia and cognitive decline. The modified amino acid N-acetyl-leucine has been associated with positive symptomatic and neuroprotective, disease-modifying effects in various studies, including animal models of NPC, observational clinical case studies, and a multinational, rater-blinded phase IIb clinical trial. Here, we describe the development of a study protocol (Sponsor Code "IB1001-301") for the chronic treatment of symptoms in adult and pediatric patients with NPC. METHODS: This multinational double-blind randomized placebo-controlled crossover phase III study will enroll patients with a genetically confirmed diagnosis of NPC patients aged 4 years and older across 16 trial sites. Patients are assessed during a baseline period and then randomized (1:1) to one of two treatment sequences: IB1001 followed by placebo or vice versa. Each sequence consists of a 12-week treatment period. The primary efficacy endpoint is based on the Scale for the Assessment and Rating of Ataxia, and secondary outcomes include cerebellar functional rating scales, clinical global impression, and quality of life assessments. DISCUSSION: Pre-clinical as well as observational and phase IIb clinical trials have previously demonstrated that IB1001 rapidly improved symptoms, functioning, and quality of life for pediatric and adult NPC patients and is safe and well tolerated. In this placebo-controlled cross-over trial, the risk/benefit profile of IB1001 for NPC will be evaluated. It will also give information about the applicability of IB1001 as a therapeutic paradigm for other rare and common neurological disorders. TRIAL REGISTRATIONS: The trial (IB1001-301) has been registered at www. CLINICALTRIALS: gov (NCT05163288) and www.clinicaltrialsregister.eu (EudraCT: 2021-005356-10). Registered on 20 December 2021. © 2023. The Author(s).

A 9-day infusion of leucine into fetal sheep potentiates fetal glucose-stimulated insulin secretion (GSIS). However, there were accompanying pancreatic structural changes that included a larger proportion of β-cells and increased vascularity. Whether leucine can acutely potentiate fetal GSIS in vivo before these structural changes develop is unknown. The mechanisms by which leucine acutely potentiates GSIS in adult islets and insulin-secreting cell lines are well known. These mechanisms involve leucine metabolism, including leucine oxidation. However, it is not clear if leucine-stimulated metabolic pathways are active in fetal islets. We hypothesized that leucine would acutely potentiate GSIS in fetal sheep and that isolated fetal islets are capable of oxidizing leucine. We also hypothesized that leucine would stimulate other metabolic pathways associated with insulin secretion. In pregnant sheep we tested in vivo GSIS with and without an acute leucine infusion. In isolated fetal sheep islets, we measured leucine oxidation with a [1-14C] l-leucine tracer. We also measured concentrations of other amino acids, glucose, and analytes associated with cellular metabolism following incubation of fetal islets with leucine. In vivo, a leucine infusion resulted in glucose-stimulated insulin concentrations that were over 50% higher than controls (P < 0.05). Isolated fetal islets oxidized leucine. Leucine supplementation of isolated fetal islets also resulted in significant activation of metabolic pathways involving leucine and other amino acids. In summary, acute leucine supplementation potentiates fetal GSIS in vivo, likely through pathways related to the oxidation of leucine and catabolism of other amino acids.

This study aimed to develop dry powder inhaler (DPI) combination formulations of ciprofloxacin and colistin for use in respiratory infections. Effects of colistin on physical stability and aerosolization of spray-dried ciprofloxacin were examined. The combination DPI formulations were produced by co-spray drying colistin and ciprofloxacin in mass ratios of 1:1, 1:3, and 1:9. Colistin and ciprofloxacin were also co-sprayed with l-leucine in the mass ratio of 1:1:1. The physical and aerosolization stability of the selected co-sprayed formulations stored at 20, 55, and 75% relative humidity (RH) were examined. Formulation characterizations were carried out using powder X-ray diffraction (PXRD) for crystallinity, scanning electron microscopy for morphology and particle size distribution, and dynamic vapor sorption for moisture sorption. Particle surface analysis was performed using X-ray photoelectron spectroscopy, energy dispersive X-ray spectrometry, and nano-time-of-flight secondary ion mass spectrometry. Potential intermolecular interactions were studied using Fourier-transform infrared spectroscopy (FTIR). Aerosol performance was evaluated using a multistage liquid impinger with a RS01 monodose inhaler device. PXRD diffractograms showed that the co-spray-dried colistin-ciprofloxacin formulation in the mass ratio (1:1) was amorphous at 55% RH for up to 60 days; whereas the co-spray-dried colistin-ciprofloxacin (1:3) and colistin-ciprofloxacin (1:9) crystallized after storage for 3 days at 55% RH. However, the extent of crystallization for the combination formulations was less as compared to the spray-dried ciprofloxacin alone formulation. Surface morphology of the co-spray-dried formulations at different concentrations did not change even after storage at 55% RH for 60 days, unlike the spray-dried ciprofloxacin alone powder which became rougher after 3 days of storage at 55% RH. Surface analysis data indicated surface enrichment of colistin in the co-spray-dried formulations. Increasing colistin concentration on the composite particles surfaces improved aerosol performance of ciprofloxacin. FTIR data demonstrated intermolecular interactions between colistin and

Compounds acting via the GPCR neurotensin receptor type 2 (NTS2) display analgesic effects in relevant animal models. Using a pharmacophore model based on known NT receptor nonpeptide compounds, we screened commercial databases to identify compounds that might possess activity at NTS2 receptor sites. Modification of our screening hit to include structural features known to be recognized by NTS1 and NTS2, led to the identification of the novel NTS2 selective nonpeptide, N-{[6-chloro-4-(2,6-dimethoxyphenyl)quinazolin-2-yl]carbonyl}-l-leucine (9). This compound is a potent partial agonist in the FLIPR assay with a profile of activity similar to that of the reference NTS2 analgesic nonpeptide levocabastine (5).

Leucine and leptin play important roles in regulating protein synthesis and degradation in skeletal muscles in vitro and in vivo. However, the objective of the present study was to determine whether leptin and leucine function synergistically in regulating protein metabolism of skeletal muscles. In the in vitro experiment, C2C12 myotubes were cultured for 2 h in the presence of 5 mm-leucine and/or 50 ng/ml of leptin. In the in vivo experiment, C57BL/6 and ob/ob mice were randomly assigned to be fed a non-purified diet supplemented with 3 % L-leucine or 2·04 % L-alanine (isonitrogenous control) for 14 d. Ob/ob mice were injected intraperitoneally with sterile PBS or recombinant mouse leptin (0·1 μg/g body weight) for 14 d. In C57BL/6 mice, dietary leucine supplementation increased (P< 0·05) plasma leptin, leptin receptor expression and protein synthesis in skeletal muscles, but reduced (P< 0·05) plasma urea and protein degradation in skeletal muscles. Dietary leucine supplementation and leptin injection increased the relative weight of the gastrocnemius and soleus muscles in ob/ob mice. Moreover, leucine and leptin treatments stimulated (P< 0·05) protein synthesis and inhibited (P< 0·05) protein degradation in C2C12 myotubes and skeletal muscles of ob/ob mice. There were interactions (P< 0·05) between the leucine and leptin treatments with regard to protein metabolism in C2C12 myotubes and soleus muscles of ob/ob mice but not in the gastrocnemius muscles of ob/ob mice. Collectively, these results suggest that leptin and leucine synergistically regulate protein metabolism in skeletal muscles both in vitro and in vivo.

This study describes the effects of long-chain fatty acids on inflammatory signaling in cultured astrocytes. Data show that the saturated fatty acid palmitic acid, as well as lauric acid and stearic acid, trigger the release of TNFα and IL-6 from astrocytes. Unsaturated fatty acids were unable to induce cytokine release from cultured astrocytes. Furthermore, the effects of palmitic acid on cytokine release require Toll-like receptor 4 rather than CD36 or Toll-like receptor 2, and do not depend on palmitic acid metabolism to palmitoyl-CoA. Inhibitor studies revealed that pharmacologic inhibition of p38 or p42/44 MAPK pathways prevents the pro-inflammatory effects of palmitic acid, whereas JNK and PI3K inhibition does not affect cytokine release. Depletion of microglia from primary astrocyte cultures using the lysosomotropic agent l-leucine methyl ester revealed that the ability of palmitic acid to trigger cytokine release is not dependent on the presence of microglia. Finally, data show that the essential ω-3 fatty acid docosahexaenoic acid acts in a dose-dependent manner to prevent the actions of palmitic acid on inflammatory signaling in astrocytes. Collectively, these data demonstrate the ability of saturated fatty acids to induce astrocyte inflammation in vitro. These data thus raise the possibility that high levels of circulating saturated fatty acids could cause reactive gliosis and brain inflammation in vivo, and could potentially participate in the reported adverse neurologic consequences of obesity and metabolic syndrome. © 2012 The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry.

Glioma is the most common type of brain tumor, and has the worst prognosis in human malignancy. Experimental evidence suggests that the use of high concentrations of various amino acids may perturb neoplastic cell growth. Thus, the aim of this study was to investigate whether essential amino acids can alter the growth and proliferation of glioma cells. Studies were performed using C6 rat glioma cell lines. High concentration of L-leucine induced growth arrest of glioma cell lines. Terminal transferase uridyl nick end labeling assay and cell cycle analysis showed that the effect of L-leucine on glioma cells growth was not cytotoxic, but rather cytostatic. Additionally, the extracellular signal-regulated protein kinase was activated in L-leucine-treated glioma cells, and inhibition of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1 (MEK) enhanced the effect of L-leucine on glioma cell growth. These data suggest that high concentration L-leucine combined with inhibition of MEK is a potential strategy for glioma cell growth arrest.

Aminoleban® EN, a nutritional product for patients with liver failure, contains three branched-chain amino acids (BCAAs): L-leucine, L-isoleucine, and L-valine. As BCAAs are extremely bitter, Aminoleban® EN has a low palatability, which is a major cause of patient noncompliance. Nutrients for liver failure often need to be taken for long periods, and poor medication compliance can cause serious problems, such as encephalopathy. Therefore it is important to suppress the bitter taste of Aminoleban® EN and thereby improve patient compliance. There are already six different flavoured powders (coffee, green-tea, apple, fruit, plum and pineapple) which can be added to Aminoleban® EN to reduce its unpleasant taste and smell, but it is possible that other factors, such as temperature, may also improve the palatability of Aminoleban® EN. In this study, flavours alone significantly decreased the bitterness intensity of Aminoleban® EN. It was thought that the sweetness and sourness of the flavoured powder would be the main factors involved in decreasing the bitterness. However, low temperature (0-5 °C) decreased the bitterness intensity of Aminoleban® EN, with or without the flavoured powders, compared with normal room temperature (25-30 °C). The sourness intensity of flavoured powders was not decreased at low temperatures, but the sweetness intensity of some flavoured powders did decrease. These results suggest that sourness can be tasted even at low temperatures. As not only the addition of flavoured powders but also low temperatures can reduce the bitterness of Aminioleban® EN, the combination of a sour-flavoured powder and a low temperature will improve the palatability of Aminoleban® EN the most.

BACKGROUND: Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) has been shown to induce colon cancer cell apoptosis in the presence of interferon-gamma. We hypothesized that co-treatment using TWEAK with other pro-apoptosis agents could sensitize death receptor-resistant colon cancer cells. MATERIALS AND METHODS: The effects of chemopreventive agents and TWEAK on cell death and apoptosis were determined using propidium iodide (PI) exclusion and M30 CytoDEATH. RESULTS: We found that 15d-PGJ(2) sensitizes colon cancer cells to TWEAK-induced apoptosis. Caspase inhibition reduced 15d-PGJ(2)-, but not 15d-PGJ(2)+TWEAK-induced apoptosis. 15d-PGJ(2) promoted reactive oxygen species (ROS) production and dissipation of mitochondrial potential (DeltaPsi(m)) that were more marked with combined treatment. ROS, DeltaPsi(m) and cell death were partially normalized by the antioxidant N-acetylcysteine. TWEAK induced nuclear factor-kappa B activation, which was attenuated by 15d-PGJ(2). 15d-PGJ(2) reduced the expression of the anti-apoptotic proteins BCL-X(L) and MCL-1, while increasing BAX and translocation of cytochrome c and apoptosis-inducing factor. CONCLUSION: 15d-PGJ(2) sensitized cancer cells to TWEAK-induced apoptosis through an ROS-dependent cell death pathway and may have chemotherapeutic utility as an apoptosis-enhancing agent.

38. Neurobiol Dis. 2009 Jul;35(1):75-81. doi: 10.1016/j.nbd.2009.04.004. Epub 2009 Apr 18. Glutamine inhibits ammonia-induced accumulation of cGMP in rat striatum limiting arginine supply for NO synthesis. Hilgier W(1), Freśko I, Klemenska E, Beresewicz A, Oja SS, Saransaari P, Albrecht J, Ziel

Amino acids, the building blocks of proteins, play significant roles in numerous physiological events in mammals. As the effects of amino acids on melanogenesis have yet to be demonstrated, the present study was conducted to identify whether amino acids, in particular alanine, glycine, isoleucine and leucine, influence melanogenesis in B16F0 melanoma cells. Glycine and L-isoleucine, but not D-isoleucine, reduced melanogenesis in a concentration-dependent manner without any morphological changes in B16F0 melanoma cells. L-Alanine and L-leucine, but not D-alanine and D-leucine, also reduced melanogenesis without any morphological changes in B16F0 melanoma cells. However these amino acids did not show a concentration-dependency. Combination of L-alanine and the other amino acids, particularly 4 amino acids combination, had an additive effect on the inhibition of melanogenesis compared with single treatment of L-alanine. None of the amino acids affected the activity of tyrosinase, a key enzyme in melanogenesis. These results suggest that L-alanine, glycine, L-isoleucine and L-leucine, but not the D-form amino acids, have a hypopigmenting effect in B16F0 melanoma cells, and that these effects are not due to the inhibition of tyrosinase activity. Combination of these 4 amino acids had the additive effect on hypopigmentation that was as similar as that of kojic acid.

Different amino acids (AAs) may exert distinct effects on postprandial glucose and insulin concentrations. A quantitative comparison of the effects of AAs on glucose and insulin kinetics in humans is currently lacking. PubMed was queried to identify intervention studies reporting glucose and insulin concentrations after acute ingestion and/or intravenous infusion of AAs in healthy adults and those living with obesity and/or type 2 diabetes (T2DM). The systematic literature search identified 55 studies that examined the effects of l-leucine, l-isoleucine, l-alanine, l-glutamine, l-arginine, l-lysine, glycine, l-proline, l-phenylalanine, l-glutamate, branched-chain AAs (i.e., l-leucine, l-isoleucine, and l-valine), and multiple individual l-AAs on glucose and insulin concentrations. Oral ingestion of most individual AAs induced an insulin response, but did not alter glucose concentrations in healthy participants. Specific AAs (i.e., leucine and isoleucine) co-ingested with glucose exerted a synergistic effect on the postprandial insulin response and attenuated the glucose response compared to glucose intake alone in healthy participants. Oral AA ingestion as well as intravenous AA infusion was able to stimulate an insulin response and decrease glucose concentrations in T2DM and obese individuals. The extracted information is publicly available and can serve multiple purposes such as computational modeling.

L-Leucine has been used to improve metabolic outcomes in glucose-intolerant rodent models. However, because studies have used different experimental models and conditions it is difficult to establish the best approach for new clinical trials evaluating the potential effects of L-leucine on glucose homeostasis. We performed a systematic review to report the effect of L-leucine supplementation on glucose homeostasis in rodents with glucose intolerance. The search engines MEDLINE and ScienceDirect were applied using MeSH terms. Thirty-four studies were included in this systematic review. Based on the current data, ingestion of 90-140 mg day-1 of isolated L-leucine in diet-induced obesity (DIO) models shows improvement in metabolic markers if offered during the development of the metabolic disorder in almost all the studies, but not after. Branched-chain amino acid supplementation was effective in streptozotocin-induced β-cells death but not in DIO models. L-Leucine supplementation seems to have an optimal dose and timing for supplementation to improve glucose homeostasis in DIO.

BACKGROUND: Amyotrophic lateral sclerosis, also known as motor neuron disease, is a progressive neuromuscular disease that causes disability and eventual death. Various amino acid preparations, the three branched-chain amino acids (L-leucine, L-valine and L-isoleucine) or, alternatively, L-threonine have been used as experimental therapy. OBJECTIVES: To examine the efficacy of amino acid therapies in prolonging survival and/or slowing the progression of amyotrophic lateral sclerosis/motor neuron disease. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group trials register (searched February 2003), MEDLINE (from January 1966 to December 2002) and EMBASE (from January 1980 to December 2002) databases and reports of specialist conferences. Authors of known studies were contacted. SELECTION CRITERIA: We included randomised or quasi-randomised trials of participants with a clinical diagnosis of amyotrophic lateral sclerosis/motor neuron disease treated with all combinations of amino acids. Our primary outcome measure was survival determined by a pooled hazard ratio of all studies. Our secondary outcome measures were (in order of priority): survival at six and 12 months, muscle strength, any validated rating scale of physical function, quality of life, proportion of patients completing therapy and proportion of patients reporting adverse events attributable to treatment. DATA COLLECTION AND ANALYSIS: We identified six eligible trials and rejected a further seven because of incomplete data or inadequate duration. Eligible studies were rated for methodological quality and missing data sought from the authors. After this examination two studies were excluded from analysis. Our pooled survival analysis was performed by the Parmar method, other statistical calculations were done using the Review Manager 4.2 software package. MAIN RESULTS: No benefit could be demonstrated for either branched-chain amino acids or L-threonine in improving survival in amyotrophic lateral sclerosis/motor neuron disease. Neither could we find evidence of an effect of either treatment on muscle strength or disability as measured by functional rating scales. No study assessed qual

BACKGROUND: Amyotrophic lateral sclerosis, also known as motor neuron disease, is a progressive neuromuscular disease that causes disability and eventual death. Various amino acid preparations, the three branched-chain amino acids (L-leucine, L-valine and L-isoleucine) or, alternatively, L-threonine have been used as experimental therapy. OBJECTIVES: To examine the efficacy of amino acid therapies in prolonging survival and/or slowing the progression of amyotrophic lateral sclerosis/motor neuron disease. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group trials register (searched February 2003), MEDLINE (from January 1966 to December 2002) and EMBASE (from January 1980 to December 2002) databases and reports of specialist conferences. Authors of known studies were contacted. SELECTION CRITERIA: We included randomised or quasi-randomised trials of participants with a clinical diagnosis of amyotrophic lateral sclerosis/motor neuron disease treated with all combinations of amino acids. Our primary outcome measure was survival determined by a pooled hazard ratio of all studies. Our secondary outcome measures were (in order of priority): survival at six and 12 months, muscle strength, any validated rating scale of physical function, quality of life, proportion of patients completing therapy and proportion of patients reporting adverse events attributable to treatment. DATA COLLECTION AND ANALYSIS: We identified six eligible trials and rejected a further seven because of incomplete data or inadequate duration. Eligible studies were rated for methodological quality and missing data sought from the authors. After this examination two studies were excluded from analysis. Our pooled survival analysis was performed by the Parmar method, other statistical calculations were done using the Review Manager 4.2 software package. MAIN RESULTS: No benefit could be demonstrated for either branched-chain amino acids or L-threonine in improving survival in amyotrophic lateral sclerosis/motor neuron disease. Neither could we find evidence of an effect of either treatment on muscle strength or disability as measured by functional rating scales. No study assessed qual