Long-Term Carbohydrate-Containing Late-Evening Snack Significantly Improves the Ratio of Branched Chain Amino Acids to Aromatic Amino Acids in Adults with Liver Cirrhosis due to Hepatitis B.

BACKGROUND: The liver is the primary organ for amino acid metabolism, and metabolic disorder of amino acids is common in liver disease. However, the characteristics of plasma amino acid profiles in patients with HBV-related cirrhosis and the impacts of late-evening snack (LES) on cirrhosis are unclear. OBJECTIVES: To investigate the characteristics of plasma amino acid profiles in patients with HBV-related chronic hepatitis, cirrhosis, and the effects of late-evening snacks on plasma amino acid profiles. METHODS: 86 patients with HBV-related cirrhosis and eighty patients with chronic hepatitis B were included in this study. The plasma amino acid profiles were measured by the amino acid analyzer. Patients were randomly divided into two groups, of which the liver cirrhosis group was to receive daily LES (n = 43) or non-LES (n = 43) for 6 months. Plasma amino acid profiles and biochemical parameters were measured in both groups at baseline and after 1, 3, and 6 months. RESULTS: Compared to healthy controls, the plasma concentration in the liver cirrhosis group of threonine, serine, glycine, glutamine, cysteine, tyrosine, phenylalanine, arginine, and methionine increased significantly (P < 0.05), while the ratio of branched chain amino acids (BCAA) to aromatic amino acids (AAA) decreased significantly (P < 0.05). A carbohydrate-predominant LES treatment resulted in a significant increase in BCAA/AAA and decrease in the level of ammonia and glutamine compared with baseline after 6 months of supplementation (P < 0.05). Patients with Child-Pugh B and C are more responsive to changes in amino acid profiles than those with Child-Pugh A. CONCLUSIONS: The application of an LES carbohydrate module for six months in liver cirrhosis patients was associated with increased BCAA/AAA and decreased level of ammonia. Patients with Child-Pugh B and C grades were the most beneficial population.

Plasma metabolites changes in male heroin addicts during acute and protracted withdrawal.

BACKGROUND: Heroin addiction and withdrawal have been associated with an increased risk for infectious diseases and psychological complications. However, the changes of metabolites in heroin addicts during withdrawal remain largely unknown. METHODS: A total of 50 participants including 20 heroin addicts with acute abstinence stage, 15 with protracted abstinence stage and 15 healthy controls, were recruited. We performed metabolic profiling of plasma samples based on ultraperformance liquid chromatography coupled to tandem mass spectrometry to explore the potential biomarkers and mechanisms of heroin withdrawal. RESULTS: Among the metabolites analyzed, omega-6 polyunsaturated fatty acids (linoleic acid, dihomo-gamma-linolenic acid, arachidonic acid, n-6 docosapentaenoic acid), omega-3 polyunsaturated fatty acids (docosahexaenoic acid, docosapentaenoic acid), aromatic amino acids (phenylalanine, tyrosine, tryptophan), and intermediates of the tricarboxylic acid cycle (oxoglutaric acid, isocitric acid) were significantly reduced during acute heroin withdrawal. Although majority of the metabolite changes could recover after months of withdrawal, the levels of alpha-aminobutyric acid, alloisoleucine, ketoleucine, and oxalic acid do not recover. CONCLUSIONS: In conclusion, the plasma metabolites undergo tremendous changes during heroin withdrawal. Through metabolomic analysis, we have identified links between a framework of metabolic perturbations and withdrawal stages in heroin addicts.

Dietary supplementation with aromatic amino acids decreased triglycerides and alleviated hepatic steatosis by stimulating bile acid synthesis in mice.

Emerging evidence shows that amino acids can modulate lipid metabolism. Aromatic amino acids (AAAs) serve as important precursors of several neurotransmitters and metabolic regulators that play a vital role in regulating nutrient metabolism. But whether AAAs have a lipid-lowering function remains unknown. Here mice were fed amino acid-defined diets containing AAAs at 1.82% and 3.64% for 3 weeks. We demonstrated that double AAA intake significantly decreased the serum and hepatic triglycerides and serum low-density lipoprotein cholesterol, but increased the high-density lipoprotein cholesterol as well as insulin tolerance. Combined metabolomic and transcriptomic analysis showed that the hepatic acidic pathway of bile acid synthesis was responsible for the improvement in lipid metabolism by AAA treatment. This study suggests that AAAs have the potential to ameliorate steatosis and provides a new alternative to improve lipid metabolism.

Mendelian Randomization Study on Amino Acid Metabolism Suggests Tyrosine as Causal Trait for Type 2 Diabetes.

Circulating levels of branched-chain amino acids, glycine, or aromatic amino acids have been associated with risk of type 2 diabetes. However, whether those associations reflect causal relationships or are rather driven by early processes of disease development is unclear. We selected diabetes-related amino acid ratios based on metabolic network structures and investigated causal effects of these ratios and single amino acids on the risk of type 2 diabetes in two-sample Mendelian randomization studies. Selection of genetic instruments for amino acid traits relied on genome-wide association studies in a representative sub-cohort (up to 2265 participants) of the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam Study and public data from genome-wide association studies on single amino acids. For the selected instruments, outcome associations were drawn from the DIAGRAM (DIAbetes Genetics Replication And Meta-analysis, 74,124 cases and 824,006 controls) consortium. Mendelian randomization results indicate an inverse association for a per standard deviation increase in ln-transformed tyrosine/methionine ratio with type 2 diabetes (OR = 0.87 (0.81-0.93)). Multivariable Mendelian randomization revealed inverse association for higher log10-transformed tyrosine levels with type 2 diabetes (OR = 0.19 (0.04-0.88)), independent of other amino acids. Tyrosine might be a causal trait for type 2 diabetes independent of other diabetes-associated amino acids.

Plasma Branched-Chain and Aromatic Amino Acids in Relation to Hypertension.

Findings of the available studies regarding the roles of branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) in hypertension are inconsistent, conflicting and inconclusive. The purpose of this study was to explore and clarify the existence of any relationships of individual BCAAs and AAAs with hypertension with adjustments for potential relevant confounders. A total of 2805 healthy controls and 2736 hypertensive patients were included in the current analysis. The associations between individual amino acids and hypertension were explored by logistic regression analyses adjusted for potential confounding variables. Among the investigated amino acids, only the BCAAs showed consistently significant positive associations with hypertension in the adjusted models (p-trend < 0.05 to 0.001). However, compared with the corresponding lowest quartile of individual BCAAs, the positive association with hypertension remained significant only in the highest quartile (p < 0.01 to 0.001). We confirmed in a relatively large cohort of subjects that BCAAs, not AAAs, demonstrated consistent positive associations with hypertension. The results display the promising potential for the use of BCAAs as relevant and accessible biomarkers, and provide perspectives on interventions directed towards the reduction in plasma BCAA levels in the prevention and management of hypertension.

Role of aromatic amino acids in pathogeneses of diabetic nephropathy in Chinese patients with type 2 diabetes.

BACKGROUND: We aimed to estimate the associations between aromatic amino acids (AAAs) and diabetic nephropathy (DN) in patients with type 2 diabetes (T2D). METHODS: We collected clinical and metabolomic data from 132 healthy subjects (HS group), 132 type 2 diabetes patients without diabetic nephropathy (T2D group) and 132 diabetic nephropathy patients (DN group) in tertiary hospital from May 2015 to August 2016. The odds ratio (OR) and 95% confidence interval (CI) were obtained by logistic regression. RESULTS: The odds ratio of tyrosine for DN increased gradually. High tyrosine was associated with an increased OR of DN (model 3, OR:0.329, 95%CI, 0.144-0.750) when comparing extreme quantiles. CONCLUSION: In Chinese patients with T2D, elevated tyrosine was associated with increased risk of DN.

Usefulness of the plasma branched-chain amino acid/aromatic amino acid ratio for predicting future cardiac events in patients with heart failure.

BACKGROUND: Heart failure (HF) is a hypercatabolic state that promotes branched-chain amino acid (BCAA) catabolic activity in the heart and skeletal muscle and reduces protein synthesis in the liver. Consequently, plasma free aromatic amino acids (AAAs) are increased. We investigated the prognostic value of the BCAA/AAA ratio (Fischer's ratio, FR) in patients with HF. METHODS: We enrolled 157 consecutive patients hospitalized for worsening HF (81 men, 76 women; mean ± SD age 75 ± 14 years). Plasma BCAA levels (i.e. total leucine, isoleucine, valine) and AAA levels (i.e. total tyrosine, phenylalanine) were measured at a time when the patients were stabilized (at discharge). FR was calculated as the combined plasma BCAA levels divided by the AAA level. Cardiac events were defined as a composite of cardiac death and hospitalization for worsening HF. RESULTS: The patients were divided into two groups based on the median FR (high-FR group: FR ≥ 3.1, n = 78; low-FR group: FR < 3.1, n = 79). Compared with the high-FR group, low-FR patients were older, had more prior hospitalizations for HF, lower albumin and cholinesterase levels, and lower geriatric nutritional risk index (GNRI). Altogether, 46 cardiac events occurred during the follow-up period (221 ± 135 days), including 14 cardiac deaths and 32 hospitalizations for worsening HF. In a Kaplan-Meier survival analysis, the low-FR group had more cardiac events than the high-FR group (log-rank, p < 0.001). The best cut-off value of FR was determined as 2.9 in the receiver operating characteristic curve for cardiac events. A multivariate Cox proportional hazards regression analysis showed that being in the low-FR group was an independent determinant of cardiac events from parameters of liver function tests and GNRI. CONCLUSIONS: FR might be useful for predicting future cardiac events in patients with HF, reflecting nutritional status which cannot be assessed by liver function tests and GNRI.

Branched-Chain and Aromatic Amino Acids Are Associated With Insulin Resistance During Pubertal Development in Girls.

PURPOSE: Cross-sectional studies in children show branched-chain and aromatic amino acids are associated with insulin resistance, but whether these associations persist from childhood to adulthood is not known. This study aimed to assess whether circulating amino acids associate with insulin resistance during pubertal development. METHODS: This was a 7.5-year longitudinal study from childhood to early adulthood. A total of 396 nondiabetic Finnish girls aged 11.2 ± .8 years at baseline participated in the study which was conducted at the Health Science Laboratory, University of Jyväskylä. Serum concentrations of glucose and insulin were determined by enzymatic photometric methods and amino acids by nuclear magnetic resonance spectroscopy. Insulin resistance was determined by the homeostatic model assessment of insulin resistance (HOMA-IR). RESULTS: All amino acids were positively associated with HOMA-IR both before and after menarche (p < .05 for all), except for histidine. Branched-chain amino acids and aromatic amino acids showed the strongest associations, the magnitude of correlation coefficients being similar before and after menarche (R2 = .064-.171). After adjusting for body mass index z-score and height, the associations between branched-chain amino acids and aromatic amino acids and HOMA-IR remained significant both before and after menarche. CONCLUSIONS: Branched-chain amino acids and aromatic amino acids associate with insulin resistance during pubertal development, independent of adiposity. Further studies are needed to determine whether changes in amino acid metabolism link pubertal hyperinsulinemia to accelerated physiological growth and/or heightened cardiometabolic risk later in life.

Neutrophils as a source of branched-chain, aromatic and positively charged free amino acids.

Neutrophils release branched-chain (valine, isoleucine, leucine), aromatic (tyrosine, phenylalanine) and positively charged free amino acids (arginine, ornithine, lysine, hydroxylysine, histidine) when adhere and spread onto fibronectin. In the presence of agents that impair cell spreading or adhesion (cytochalasin D, fMLP, nonadhesive substrate), neutrophils release the same amino acids, except for a sharp decrease in hydroxylysine and an increase in phenylalanine, indicating their special connection with cell adhesion. Plasma of patients with diabetes is characterized by an increased content of branched-chain and aromatic amino acids and a reduced ratio of arginine/ornithine compared to healthy human plasma. Our data showed that the secretion of neutrophils, regardless of their adhesion state, can contribute to this shift in the amino acid content. Abbreviations: BCAAs: branched-chain amino acids; Е2: 17ß-estradiol; LPS: lipopolysaccharide from Salmonella enterica serovar Typhimurium; fMLP: N-formylmethionyl-leucyl-phenylalanine.

Plasma branched chain/aromatic amino acids, enriched Mediterranean diet and risk of type 2 diabetes: case-cohort study within the PREDIMED Trial.

AIMS/HYPOTHESIS: Branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) are associated with type 2 diabetes. However, repeated measurements of BCAA/AAA and their interactions with dietary interventions have not been evaluated. We investigated the associations between baseline and changes at 1 year in BCAA/AAA with type 2 diabetes in the context of a Mediterranean diet (MedDiet) trial. METHODS: We included 251 participants with incident type 2 diabetes and a random sample of 694 participants (641 participants without type 2 diabetes and 53 overlapping cases) in a case-cohort study nested within the PREvención con DIeta MEDiterránea (PREDIMED) trial. Participants were randomised to a MedDiet+extra-virgin olive oil (n = 273), a MedDiet+nuts (n = 324) or a control diet (n = 295). We used LC-MS/MS to measure plasma levels of amino acids. Type 2 diabetes was a pre-specified secondary outcome of the PREDIMED trial. RESULTS: Elevated plasma levels of individual BCAAs/AAAs were associated with higher type 2 diabetes risk after a median follow-up of 3.8 years: multivariable HR for the highest vs lowest quartile ranged from 1.32 for phenylalanine ([95% CI 0.90, 1.92], p for trend = 0.015) to 3.29 for leucine ([95% CI 2.03, 5.34], p for trend<0.001). Increases in BCAA score at 1 year were associated with higher type 2 diabetes risk in the control group with HR per SD = 1.61 (95% CI 1.02, 2.54), but not in the MedDiet groups (p for interaction <0.001). The MedDiet+extra-virgin olive oil significantly reduced BCAA levels after 1 year of intervention (p = 0.005 vs the control group). CONCLUSIONS/INTERPRETATION: Our results support that higher baseline BCAAs and their increases at 1 year were associated with higher type 2 diabetes risk. A Mediterranean diet rich in extra-virgin olive oil significantly reduced the levels of BCAA and attenuated the positive association between plasma BCAA levels and type 2 diabetes incidence. Clinical trial number: SRCTN35739639 ( www.controlled-trials.com ).

Identification of serum metabolites associated with obesity and traditional risk factors for metabolic disease in Chinese adults.

BACKGROUND AND AIMS: Obesity is a major worldwide health problem and is often associated with many metabolic diseases. Levels of several serum-specific metabolites may be altered in patients with these metabolic diseases. We aimed to investigate the associations of serum metabolite levels with obesity and traditional risk factors for metabolic disease in Chinese individuals. METHODS AND RESULTS: Six-hundred Chinese individuals undergoing annual physical exams were recruited and categorized into overweight/obese and control groups (1:1 ratio). We simultaneously quantified the serum lysophosphatidylcholine (LPC), branched-chain amino acids (BCAA), aromatic amino acids (AAA), 25-hydroxyvitamin D, glutamine (Gln), glutamic acid (Glu), and Gln/Glu ratio levels using our previously established targeted serum metabolomic method. The overweight/obesity group had significantly higher levels of BCAA, AAA, and Glu, as well as lower levels of unsaturated LPC, Gln, and Gln/Glu, than the control group. Correlation analyses revealed significant and positive relationships of saturated LPC, BCAA, AAA, and Glu with blood pressure, glucose, triglycerides, apolipoprotein B, and high-sensitivity C-reactive protein, while unsaturated LPC, Gln, Gln/Glu, and 25-hydroxyvitamin D exhibited an opposite trend. In the multifactor logistic regression model, low unsaturated LPC and Gln/Glu, as well as high BCAA and AAA levels, were found to be independent risk factors for obesity; the odds ratios (95% confidence interval) of the highest quartile compared to the lowest quartile were 0.241 (0.139-0.417), 0.436 (0.252-0.755), 3.944 (2.094-7.430), and 2.357 (1.274-4.361) (P < 0.01), respectively. CONCLUSION: LPC, BCAA, AAA, and Gln/Glu are significantly related to obesity development and risk factors of some metabolic diseases.

A gut bacterial pathway metabolizes aromatic amino acids into nine circulating metabolites.

The human gut microbiota produces dozens of metabolites that accumulate in the bloodstream, where they can have systemic effects on the host. Although these small molecules commonly reach concentrations similar to those achieved by pharmaceutical agents, remarkably little is known about the microbial metabolic pathways that produce them. Here we use a combination of genetics and metabolic profiling to characterize a pathway from the gut symbiont Clostridium sporogenes that generates aromatic amino acid metabolites. Our results reveal that this pathway produces twelve compounds, nine of which are known to accumulate in host serum. All three aromatic amino acids (tryptophan, phenylalanine and tyrosine) serve as substrates for the pathway, and it involves branching and alternative reductases for specific intermediates. By genetically manipulating C. sporogenes, we modulate serum levels of these metabolites in gnotobiotic mice, and show that in turn this affects intestinal permeability and systemic immunity. This work has the potential to provide the basis of a systematic effort to engineer the molecular output of the gut bacterial community.

Specific plasma amino acid disturbances associated with metabolic syndrome.

PURPOSE: The primary objective of the present study was to examine the association between branched chain and aromatic amino acid profiles (BCAA and AAA respectively) and the metabolic syndrome (MS), and to evaluate the clinical utility of these associations in the diagnostic process. METHODS: Two hundred and sixty three healthy men with MS [MS(+): n = 165] and without MS [MS(-): n = 98] were enrolled in the observational study. Anthropometrical, biochemical, and amino acid measurements were performed. The ability of the BCAA and AAA to discriminate subjects with MS and insulin resistance was tested. Based on logistic discrimination, a multivariate early MS diagnostic model was built, and its discrimination properties were evaluated. RESULTS: Two functionally independent amino acid clusters were identified. BCAA and phenylalanine differed significantly between MS(+) and MS(-) participants (P = 0.003). These factors were also found to be indicators of MS(+) individuals (AUC: 0.66; 95% CI: 0.5757-0.7469), and correlated with cardiometabolic factors. No statistically significant differences in amino acid concentrations between those with and without insulin resistance were noted, and none of the amino groups were indicators of insulin resistance. The proposed MS multivariate diagnostic model consisted of phenylalanine, insulin, leptin, and adiponectin, and had good discrimination properties [AUC 0.79; 95% CI: 0.7239-0.8646]. CONCLUSIONS: MS is associated with selective BCAA and AAA profile disturbances, which could be part of cardiometabolic disease pathogenesis and derive neither directly from insulin sensitivity impairment, nor obesity or muscle mass. The MS diagnostic model developed and described herein should be validated in future studies.

Amino acid profile and metabolic syndrome in a male Mediterranean population: A cross-sectional study.

BACKGROUND AND AIMS: The metabolic syndrome (MetS) refers to a cluster of clinically relevant factors that increases the risk of cardiovascular diseases and all-cause mortality. Circulating levels of several amino acids and metabolites related to one-carbon metabolism have been associated with cardiometabolic risk factors and MetS. We aimed to identify the amino acid profile that is significantly associated with MetS among an all male Mediterranean population. METHODS AND RESULTS: One hundred middle-aged men (54.6 ± 8.9 years) participated in a cross-sectional study carried out during 2011-2012. The International Diabetes Federation (IDF) criteria were used to define MetS. Fasting plasma levels of 20 common amino acids and 15 metabolites related to amino acid and one-carbon metabolism were measured using gas chromatography (GC-MS/MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS). Principal components analysis was applied. Fifty-six participants fulfilled the IDF criteria for defining MetS. Five factors were extracted from the 35 measured metabolites. The branched-chain amino acids/aromatic amino acids (BCAA/AAA) related pattern and the glutamine/glycine/serine/asparagine (Gln/Gly/Ser/Asn) related pattern were significantly associated with MetS (odds ratio, 95% confidence interval; 6.41, 2.43-16.91, and 0.47, 0.23-0.96, respectively) after adjustment for age, current smoking status, physical activity level and medical treatment for hypertension, dyslipidaemia, type 2 diabetes mellitus. Further adjustment for liver function markers (i.e. glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, and γ-glutamyltransferase), and plasma adiponectin levels did not significantly affect the associations. CONCLUSION: The BCAA/AAA pattern was positively associated, while the Gln/Gly/Ser/Asn pattern was inversely associated with established cardiometabolic risk factors and MetS. Plasma adiponectin levels or markers of liver function did not significantly affect these associations.

Targeted metabolomics analysis of aromatic amino acids and their gut microbiota-host cometabolites in rat serum and urine by liquid chromatography coupled with tandem mass spectrometry.

Gut microbiota-host cometabolites are closely related to various diseases. Monitoring dynamic changes of cometabolites can provide a more comprehensive understanding of pathophysiology. Here, a novel liquid chromatography-tandem mass spectrometry method was performed for the analysis of aromatic amino acids and their gut microbiota-host cometabolites in rat serum and urine. In the developed method, seven key gut microbiota-host cometabolites were chromatographically separated on a Kinetex Phenyl-Hexyl column by gradient elution, and the run time was 6 min. Serum and urine were extracted by protein precipitation. This method was linear between 10.20 and 1000.00 ng/mL for phenylalanine and p-cresyl sulfate; 25.60-2500.00 ng/mL for tryptophan; 51.20-5000.00 ng/mL for tyrosine, indole, and indoxyl sulfate; and 75.50-7500.00 ng/mL for p-cresol. The linearity, accuracy, precision, and recovery of seven analytes were all satisfactory. The method was sufficiently sensitive and robust. It was successfully applied to characterize the alterations of gut microbiota-host cometabolites in inflammatory disorders. All of these results suggest that the developed method is able to simultaneously monitor aromatic amino acids and their gut microbiota-host cometabolites. This method will be expected to be a valuable tool for clinical researches and comprehensive studies of the pathophysiological roles.

A role for plasma aromatic amino acids in injurious pecking behavior in laying hens.

Injurious pecking, including feather pecking (FP), is one of the most prevalent causes of mortality for commercial laying hens. The underlying biological mechanisms of FP are not yet fully understood, but they could be related to alterations in the serotonin (5-HT) and/or dopamine (DA) circuits within the brain. In the past, the central synthesis of 5-HT and DA was found to be influenced by the availability of their precursors, aromatic amino acids (AAA) such as tryptophan (TRP), phenylalanine (PHE), and tyrosine (TYR), in blood plasma, which are transported across the blood-brain-barrier into the brain. Because knowledge about plasma levels of AAA in laying hens is very limited, the present study compared the AAA profiles of a large sample of laying hens from two genetic lines: one selected for low mortality (LM) due to injurious pecking (n=129 birds) and one high production line (HP) selected for high egg-production only (n=132 birds). Head, comb, and feather covering were scored at the end of the experiment. Blood samples were collected at weeks 24 and 29 of age and were analysed for AAA using high performance liquid chromatography. Neither FP nor feather damage was observed in the present study, but aggressive pecking directed at the head/neck area occurred in several groups with an onset of this aberrant behavior between weeks 22 and 29. Eight HP pens and seven LM pens were affected by severe head/comb injuries inflicted via aggressive pecking. Therefore, our exploratory data analysis focused upon the possible interplay between the variability of our outcome measures (absolute levels of AAA in plasma as well as the ratios PHE/TYR and TRP/(PHE+TYR)) and the aggressive head/comb pecking as an expression of social stress within the pens. We found significantly lower TRP availability relative to PHE and TYR (TRP/(PHE+TYR) ratio) and higher TYR concentrations at week 24 in pens with an early onset of injurious aggressive behavior at weeks 22-23. This was most pronounced in the LM line, but at week 29, TRP availability normalized in both lines. It was furthermore evident that in LM birds, higher aggressive pecking activity per pen was associated with higher TYR levels (n=78 birds, r=0.643, p<0.001) and lower TRP/(PHE+TYR) ratios at week 24 (r=-0.541, p<0.001). In the HP birds, these associations were of lower strength and were negatively correlated (TYR: n=73, r=-0.308, p=0.005; TRP/(PHE/TYR) ratio: r=0.314, p=0.004). Our findings indicate that in LM birds, lower TRP availability at week 24 may be attributable to higher stress levels in pens where injurious aggressive pecking developed early on. These findings may lay the important groundwork for the analysis of AAA plasma levels as a useful avenue of research to investigate underlying physiological mechanisms of behavioral problems in laying hens.

Attenuation of Carbon Tetrachloride-Induced Hepatic Toxicity by a Dietary Supplement.

Advanced liver disease (ALD) is often characterized with overt malnutrition and liver fibrosis. In this study, a dietary supplement (DS) was first developed, including branch chain amino acids, fat soluble vitamins, zinc, medium chain triglycerides, soy lecithin, L-carnitine, and n-3 polyunsaturated fatty acids. Benefits of DS were then tested using an ALD rat model treated with carbon tetrachloride (CCl4) for 6, 8, and 10 weeks, respectively. Our study showed that CCl4-induced drop of serum albumin and ratio of branch chain to aromatic amino acids were significantly prevented at all three time points. DS also mitigated CCl4-induced elevation of classical liver function markers (alanine aminotransferase, aspartate aminotransferase, and bilirubin) at certain time points, depending on specific liver function markers. Moreover, CCl4-induced liver fibrosis was strongly inhibited at all three time points in a transforming growth factor beta (TGF-ß) independent manner. These findings indicated multi-faceted benefits of DS in this animal model, suggesting that it could be a useful adjunctive treatment of ALD in clinic.

Plasma Amino Acid Concentrations Predict Mortality in Patients with End-Stage Liver Disease.

BACKGROUND: The liver plays a key role in amino acid metabolism. In former studies, a ratio between branched-chain and aromatic amino acids (Fischer's ratio) revealed associations with hepatic encephalopathy. Furthermore, low concentrations of branched-chain amino acids were linked to sarcopenia in literature. Encephalopathy and sarcopenia are known to dramatically worsen the prognosis. Aim of this study was to investigate a complex panel of plasma amino acids in the context of mortality in patients with end-stage liver disease. METHODS: 166 patients evaluated for orthotopic liver transplantation were included. 19 amino acids were measured from citrated plasma samples using mass spectrometry. We performed survival analysis for plasma amino acid constellations and examined the relationship to established mortality predictors. RESULTS: 33/166 (19.9%) patients died during follow-up. Lower values of valine (p<0.001), Fischer's ratio (p<0.001) and valine to phenylalanine ratio (p<0.001) and higher values of phenylalanine (p<0.05) and tyrosine (p<0.05) were significantly associated with mortality. When divided in three groups, the tertiles discriminated cumulative survival for valine (p = 0.016), phenylalanine (p = 0.024) and in particular for valine to phenylalanine ratio (p = 0.003) and Fischer's ratio (p = 0.005). Parameters were also significantly correlated with MELD and MELD-Na score. CONCLUSIONS: Amino acids in plasma are valuable biomarkers to determine increased risk of mortality in patients with end-stage liver disease. In particular, valine concentrations and constellations composed of branched-chain and aromatic amino acids were strongly associated with prognosis. Due to their pathophysiological importance, the identified amino acids could be used to examine individual dietary recommendations to serve as potential therapeutic targets.

Branched-chain and aromatic amino acids, insulin resistance and liver specific ectopic fat storage in overweight to obese subjects.

BACKGROUND & AIMS: Amino acids may interfere with insulin action, particularly in obese individuals. We hypothesized that increased circulating branched-chain and aromatic amino acids herald insulin resistance and ectopic fat storage, particularly hepatic fat accumulation. METHODS AND RESULTS: We measured fasting branched-chain and aromatic amino acids (tryptophan, tyrosine, and phenylalanine) by mass spectrometry in 111 overweight to obese subjects. We applied abdominal magnetic resonance imaging and spectroscopy to assess adipose tissue distribution and ectopic fat storage, respectively. Plasma branched-chain amino acids concentrations were related to insulin sensitivity and intrahepatic fat independent from adiposity, age and gender, but not to abdominal adipose tissue or intramyocellular fat. CONCLUSIONS: In weight stable overweight and obese individuals, branched-chain amino acid concentrations are specifically associated with hepatic fat storage and insulin resistance.

Branched-chain and aromatic amino acid profiles and diabetes risk in Chinese populations.

Recent studies revealed strong evidence that branched-chain and aromatic amino acids (BCAAs and AAAs) are closely associated with the risk of developing type 2 diabetes in several Western countries. The aim of this study was to evaluate the potential role of BCAAs and AAAs in predicting the diabetes development in Chinese populations. The serum levels of valine, leucine, isoleucine, tyrosine, and phenylalanine were measured in a longitudinal and a cross sectional studies with a total of 429 Chinese participants at different stages of diabetes development, using an ultra-performance liquid chromatography triple quadruple mass spectrometry platform. The alterations of the five AAs in Chinese populations are well in accordance with previous reports. Early elevation of the five AAs and their combined score was closely associated with future development of diabetes, suggesting an important role of these metabolites as early markers of diabetes. On the other hand, the five AAs were not as good as existing clinical markers in differentiating diabetic patients from their healthy counterparts. Our findings verified the close correlation of BCAAs and AAAs with insulin resistance and future development of diabetes in Chinese populations and highlighted the predictive value of these markers for future development of diabetes.