L-Isoleucine

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.

OBJECTIVE: This study aimed to comparatively evaluate the effects of polyherbal, chlorhexidine (CHX), and normal saline (NCC) mouthwashes on oral microbiome composition, microbial metabolic pathways, and patient-reported outcomes, with the goal of assessing the potential of polyherbal mouthwash as a natural alternative to CHX for managing gingivitis, while aiming to minimize CHX-associated microbial dysbiosis. METHODS: A randomized, double-blind trial was conducted among 27 patients with gingivitis, randomly assigned to polyherbal, CHX, or NCC mouthwash groups. Participants used the assigned mouthwash twice daily for 7 days. Saliva samples were analyzed via 16 S rRNA sequencing to assess microbial diversity (alpha and beta) and taxonomic composition. Differential taxa and pathways were identified using FDR-corrected Wilcoxon tests and log₂ fold-change analysis. Patient-reported outcomes were evaluated using numerical rating scales (NRS). RESULTS: The polyherbal mouthwash demonstrated significantly higher patient acceptability than CHX and NCC, with superior scores in taste, smell, texture, moisture retention, overall satisfaction, and willingness for continued use (p < 0.05). While CHX exhibited strong antimicrobial activity, its alcohol-containing formulation markedly disrupted microbial diversity, increased potentially dysbiotic genera (Streptococcus, Porphyromonas), and altered 23 metabolic pathways associated with dysbiosis. In contrast, the polyherbal mouthwash-which also contained cetylpyridinium chloride (CPC)- selectively increased beneficial genera (Amnipila, Absconditabacteriales [SR1], Peptostreptococcus), preserved overall microbial diversity, and modulated only two pathways, notably upregulating L-isoleucine biosynthesis. CONCLUSION: The polyherbal mouthwash represents a promising alternative to CHX, demonstrating selective microbial modulation, preservation of microbiome stability, and enhanced patient acceptability. These findings support its potential integration into routine oral healthcare as a microbiome-friendly and patient-acceptable solution. Further studies are warranted to evaluate CPC-free polyherbal formulations across larger and more d

The study investigates the effects of wheat biscuits supplemented with plant flours originating from legumes/seeds enriched either in L-arginine (L-arg) or branched-chain amino acids (BCAAs) on postprandial glucose response of healthy subjects. Gastrointestinal hormone and amino acid responses as well as subjective appetite sensations are also evaluated. Subjects consumed wheat-based biscuits, enriched either in L-arg (ArgB) or BCAAs (BCAAsB) or a conventional wheat biscuit (CB) or a glucose solution (GS) in an acute randomized crossover design. Responses of glucose, insulin, ghrelin, glucagon-like peptide-1 (GLP-1), peptide YY (PYY) and glicentin, as well as those of L-arginine, L-leucine, L-isoleucine and L-valine, were evaluated over 180 min. Consumption of ArgB and BCAAsB elicited lower glucose iAUC compared to GS (p < 0.05). A lower iAUC for insulin was observed after consumption of BCAAsB (p < 0.05 compared to CB and ArgB), while ArgB elicited higher iAUC for GLP-1 accompanied by higher glicentin response (p < 0.05 compared to CB). BCAAsB and ArgB increased postprandial amino acid concentrations and caused stronger satiety effects compared to CB. Increasing protein content of wheat biscuits with supplementation of plant flours originating from legumes/seeds decreases postprandial glycemia and provides with healthier snack alternatives which can easily be incorporated into diet.

BACKGROUND: The 18 kDa translocator protein (TSPO), previously known as the peripheral- type benzodiazepine receptor, plays a key role for the synthesis of neurosteroids by promoting transport of cholesterol from the outer to the inner mitochondrial membrane, which is the ratelimiting step in neurosteroid biosynthesis. Neurosteroids interact with nonbenzodiazepine site of GABAa receptor causing an anxiolytic effect without the side effects. METHODS: Using the original peptide drug-based design strategy, the first putative dipeptide ligand of the TSPO N-carbobenzoxy-L-tryptophanyl-L-isoleucine amide (GD-23) was obtained. Molecular docking of GD-23 in the active pocket of the TSPO receptor using Glide software was carried out. The lead compounds GD-23 and its analogues were synthesized using activated succinimide esters coupling method. The anxiolytic activity of GD-23 and its analogues was investigated in vivo, using two validated behavioral tests, illuminated open field and elevated plus-maze. RESULTS: The in vivo studies revealed that the following parameters are necessary for the manifestation of anxiolytic activity of new compounds: the L-configuration of tryptophan, the presence of an amide group at the C-terminus, the specific size of the N-acyl substituent at the Nterminus. Compound GD-23 (N-carbobenzoxy-L-tryptophanyl-L-isoleucine amide) demonstrated a high anxiolytic-like effect in the doses of 0.05-1.0 mg/kg i.p. comparable with that of diazepam. Compound GD-23 was also active in the open field test when was administered orally in the doses of 0.1-5.0 mg/kg. The involvement of TSPO receptor in the mechanism of anxiolytic-like activity of new compounds was proved by the antagonism of compound GD-23 with TSPO selective inhibitor PK11195 as well as with inhibitors of enzymes which are involved in the biosynthesis of neurosteroids, trilostane and finasteride. CONCLUSION: A series of N-acyl-tryptophanyl-containing dipeptides were designed and synthesized as 18 kDa translocator protein (TSPO) ligands. Using a drug-based peptide design method a series of the first dipeptide TSPO ligands have been designed and synthesized and their anxiolytic activity has been

Holotrichia parallela (Coleoptera: Scarabaeoidea) is a notorious pest of many crops. To improve the effectiveness of its female-produced sex pheromone (L-isoleucine methyl ester:(R)-(-)-linalool = 6:1), 14 plant volatiles, including dodecanoic acid, dodecanal, farnesol, α-farnesene, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, (Z)-3-hexenyl acetate, (E)-2-hexenyl acetate, (R)-(+)-limonene, α-phellandrene, α-pinene, ocimene, methyl benzoate, and benzaldehyde, were individually evaluated using electroantennography and olfactometer assays. (E)-2-Hexenyl acetate and (Z)-3-hexenyl acetate were found to elicit the strongest responses in both males and females. Further testing of these two compounds in mixtures with the sex pheromone indicated that (E)-2-hexenyl acetate had a stronger synergistic effect than (Z)-3-hexenyl acetate. Field evaluations showed that mixtures of (E)-2-hexenyl acetate and the sex pheromone resulted in significantly higher catches than the sex pheromone alone. Using a 5:1 mixture of the sex pheromone and (E)-2-hexenyl acetate, the maximum number of females per trap per day was 14, showing a synergistic effect of a factor of four. For males, a 3:1 mixture of the sex pheromone and (E)-2-hexenyl acetate yielded a maximum number of 310 individuals per trap per day, equivalent to a synergistic effect of 175%. These results may provide the basis for the development of efficient pest management systems against H. parallela using plant volatiles and insect sex pheromones.

ETHNOPHARMACOLOGICAL RELEVANCE: The compatibility of Angelicae Sinensis Radix (Danggui) and Carthami Flos (Honghua), a famous herb pair Gui-Hong, can produce synergistic and complementary hematinic effects. Our previous studies have indicated that Gui-Hong has therapeutic potential treatment in hemolytic and aplastic anemia (HAA). The present study aimed to investigate the hematinic effects of Danggui, Honghua and Gui-Hong on HAA rats induced by acetyl phenylhydrazine (APH) and cyclophosphamide (CP) and to explore the underlying hematinic regulation mechanisms. MATERIALS AND METHODS: Rats were divided into 5 groups, and drugs were administered by oral gavage one time each day for continuous 7 days from the experiment began. Urine and plasma were analyzed by ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS). Partial least-squares discriminate analysis (PLS-DA) models were built to evaluate the therapeutic effects of Danggui, Honghua and Gui-Hong. Pearson correlation matrix analysis method was used to discover the correlations between potential biomarkers and biochemical indicators of HAA rats. RESULTS: Seven potential biomarkers contribute to the separation of model group and control group were tentatively identified. The levels of l-kynurenine, phenylalanine, nicotinic acid and sphingosine increased significantly (P<0.05) in HAA rats, while the levels of l-isoleucine, l-tyrosine and serotonin decreased significantly (P<0.05) in comparison with control rats. Those endogenous metabolites were chiefly involved in phenylalanine, tyrosine and tryptophan biosynthesis, valine, leucine and isoleucine biosynthesis, tryptophan metabolism and tyrosine metabolism. The metabolic deviations could be regulated closer to normal level after Danggui, Honghua and Gui-Hong intervention. In term of hematinic effects, Gui-Hong was the most effective as shown by the relative distance in PLS-DA score plots and relative intensity of potential biomarkers. The result reflected the synergic action between Danggui and Honghua. The above results were found to be reasonable in explaining the hematinic effects mechanism of Gui-H

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.

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.

Icofungipen (PLD-118) is the representative of a novel class of antifungals, beta amino acids, active against Candida species. It has been taken through phase II clinical trials. The compound actively accumulates in yeast, competitively inhibiting isoleucyl-tRNA synthetase and consequently disrupting protein biosynthesis. As a result, in vitro activity can be studied only in chemically defined growth media without free amino acids that would compete with the uptake of the compound. The MIC of icofungipen was reproducibly measured in a microdilution assay using yeast nitrogen base medium at pH 6 to 7 after 24 h of incubation at 30 to 37 degrees C using an inoculum of 50 to 100 CFU/well. The MICs for 69 Candida albicans strains ranged from 4 to 32 microg/ml. This modest in vitro activity contrasts with the strong in vivo efficacy in C. albicans infection. This was demonstrated in a lethal model of C. albicans infection in mice and rats in which icofungipen showed dose-dependent protection at oral doses of 10 to 20 mg/kg of body weight per day in mice and 2 to 10 mg/kg/day in rats. The in vivo efficacy was also demonstrated against C. albicans isolates with low susceptibility to fluconazole, indicating activity against azole-resistant strains. The efficacy of icofungipen in mice and rats was not influenced by concomitant administration of equimolar amounts of L-isoleucine, which was shown to antagonize its antifungal activity in vitro. Icofungipen shows nearly complete oral bioavailability in a variety of species, and its in vivo efficacy indicates its potential for the oral treatment of yeast infections. Dual effects of gabapentin and pregabalin on glutamate release at rat entorhinal synapses in vitro. Cunningham MO(1), Woodhall GL, Thompson SE, Dooley DJ, Jones RS. Author information: (1)Department of Physiology, School of Medical Sciences, University Walk, University of Bristol, Bristol, BS8 1TD, UK. We have recently shown that the anticonvulsant drugs phenytoin, lamotrigine and sodium valproate all reduce the release of glutamate at synapses in the entorhinal cortex in vitro. In the present investigation we determined whether this property was shared by gab

10. Eur J Neurosci. 2004 Sep;20(6):1566-76. doi: 10.1111/j.1460-9568.2004.03625.x. Dual effects of gabapentin and pregabalin on glutamate release at rat entorhinal synapses in vitro. Cunningham MO(1), Woodhall GL, Thompson SE, Dooley DJ, Jones RS. Author information: (1)Department of Physiology,

The purpose of the present study was to quantify the degree of suppression of the bitterness of two amino acids (L-isoleucine (L-Ile), and L-phenylalanine (L-Phe)) which could be achieved by the addition of various test chemicals, and to examine the mechanism of this bitterness suppression. The test chemicals used were two sweeteners (sucrose, aspartame), NaCl, various acidic (L-aspartic acid, L-glutamic acid), or basic (L-histidine, L-lysine and L-arginine) amino acids, tannic acid and phosphatidic acid. The combination of L-arginine (L-Arg) and NaCl together was the most effective in reducing the bitterness of 100 mM L-Ile and L-Phe solutions in human gustatory sensation tests. Even in bitterness of 0.1 mM quinine solution, L-Arg was also successful in reducing the bitterness. This bitterness-suppression effect was specific to L-Arg and not to the other basic amino acids. No comparable taste-masking effect was observed for the acidic amino acids. The artificial taste sensor failed to predict completely the bitterness-suppressing effect of L-Arg. It seems likely that the bitterness-suppressing effect of L-Arg is mediated not only by binding at the receptor site, but also elsewhere in the process of bitterness perception, such as a direct effect on the sodium channel. It is conjectured that the guanidinium group of L-Arg may interact with sodium channels in taste bud membranes.

Saturated and unsaturated fatty acids and fatty acid derivatives were examined for their growth-inhibitory effects towards three selected oral bacteria: Porphyromonas gingivalis, Selenomonas artemidis, and Streptococcus sobrinus. Of the 45 compounds surveyed, only one, myristoleic acid, was inhibitory towards S. artemidis at a concentration < 100 micrograms/ml. cis-Hexadecenoic and cis-octadecenoic acids were generally inhibitory towards P. gingivalis and S. sobrinus, but there was no correlation between the position of the double bond and the minimum inhibitory concentration. Supra-minimum inhibitory concentrations of palmitoleic acid did not promote leakage of intracellular materials from either P. gingivalis or S. sobrinus, nor was L-isoleucine uptake by S. sobrinus inhibited. Fatty acids and derivatives were also examined for prospective synergistic or antagonistic interactions with thymol vis-à-vis growth inhibition of the test strains. Lauric acid and myristic acid each behaved synergistically with thymol to inhibit the growth of at least one test strain, whereas cis-10-heptadecenoic acid and thymol were noticeably antagonistic towards the growth of S. sobrinus.

Smooth- and rough-colony variants of Mycobacterium avium serovar 4 were treated with three classes of drugs. The drugs were chosen for their potential inhibitory effects on the biosynthesis of the cell envelope-associated serovar-specific glycopeptidolipid antigens. Growth was monitored radiometrically with a BACTEC 460-TB instrument, and MICs were determined for each drug. Both variants were then treated with inhibitory drugs in combination with antimicrobial agents that have demonstrated effectiveness against M. avium. No growth inhibition was observed with 6-fluoro-6-deoxy-D-glucose or avidin. Inhibitors of glycosylation, i.e., 2-deoxy-D-glucose, bacitracin, and ethambutol, were inhibitory to smooth- and rough-colony variants, whereas drugs that inhibit peptide synthesis, i.e., N-carbamyl-L-isoleucine and m-fluoro-phenylalanine, were more inhibitory for the rough-colony variant. Cerulenin, which affects fatty acid synthesis, was inhibitory for both variants, but it appeared to be more effective at inhibiting the growth of the smooth-colony variant at equivalent concentrations. Generally, when inhibitors of glycosylation were used with sparfloxacin and amikacin, a synergistic effect was observed for only the smooth variant. When drugs that affect peptide synthesis were used in combination with amikacin, a synergistic effect was observed for the rough variant, and when cerulenin was used in combination with sparfloxacin or amikacin, a synergistic effect was observed for both variants. Lipid analysis revealed that although the rough variant lacks the serovar-specific glycopeptidolipid antigens, it does possess a group of phenylalanine-isoleucine-containing lipopeptides that may explain its different susceptibility patterns to m-fluoro-phenylalanine and N-carbamyl-L-isoleucine. The significance of these results is discussed with reference to various components in the cell envelope and their importance in cell wall permeability.

Bladder cancer (BCa) research relying on Omics approaches has increased over the last few decades, improving the understanding of BCa pathology and contributing to a better molecular classification of BCa subtypes. To gain further insight into the molecular profile underlying the development of BCa, a systematic literature search was performed in PubMed until November 2023, following the PRISMA guidelines. This search enabled the identification of 25 experimental studies using mass spectrometry or nuclear magnetic resonance-based approaches to characterize the metabolite signature associated with BCa. A total of 1562 metabolites were identified to be altered by BCa in different types of samples. Urine samples displayed a higher likelihood of containing metabolites that are also present in bladder tumor tissue and cell line cultures. The data from these comparisons suggest that increased concentrations of L-isoleucine, L-carnitine, oleamide, palmitamide, arachidonic acid and glycoursodeoxycholic acid and decreased content of deoxycytidine, 5-aminolevulinic acid and pantothenic acid should be considered components of a BCa metabolome signature. Overall, molecular profiling of biological samples by metabolomics is a promising approach to identifying potential biomarkers for early diagnosis of different BCa subtypes. However, future studies are needed to understand its biological significance in the context of BCa and to validate its clinical application.

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.

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