Precision Medicine for Blood Glutamate Grabbing in Ischemic Stroke.

Glutamate grabbers, such as glutamate oxaloacetate transaminase (GOT), have been proposed to prevent excitotoxicity secondary to high glutamate levels in stroke patients. However, the efficacy of blood glutamate grabbing by GOT could be dependent on the extent and severity of the disruption of the blood-brain barrier (BBB). Our purpose was to analyze the relationship between GOT and glutamate concentration with the patient's functional status differentially according to BBB serum markers (soluble tumor necrosis factor-like weak inducer of apoptosis (sTWEAK) and leukoaraiosis based on neuroimaging). This retrospective observational study includes 906 ischemic stroke patients. We studied the presence of leukoaraiosis and the serum levels of glutamate, GOT, and sTWEAK in blood samples. Functional outcome was assessed using the modified Rankin Scale (mRS) at 3 months. A significant negative correlation between GOT and glutamate levels at admission was shown in those patients with sTWEAK levels > 2900 pg/mL (Pearson's correlation coefficient: -0.249; p < 0.0001). This correlation was also observed in patients with and without leukoaraiosis (Pearson's correlation coefficients: -0.299; p < 0.001 vs. -0.116; p = 0.024). The logistic regression model confirmed the association of higher levels of GOT with lower odds of poor outcome at 3 months when sTWEAK levels were >2900 pg/mL (OR: 0.41; CI 95%: 0.28-0.68; p < 0.0001) or with leukoaraiosis (OR: 0.75; CI 95%: 0.69-0.82; p < 0.0001). GOT levels are associated with glutamate levels and functional outcomes at 3 months, but only in those patients with leukoaraiosis and elevated sTWEAK levels. Consequently, therapies targeting glutamate grabbing might be more effective in patients with BBB dysfunction.

Aldehyde dehydrogenase 2-associated changes in pharmacokinetics, locomotor function and peripheral glutamic acid and gamma-aminobutyric acid levels during acute alcohol intoxication in male mice.

The insufficiency of human aldehyde dehydrogenase 2 (ALDH2) has been consistently associated with high blood acetaldehyde levels and impaired locomotor function during acute alcohol intoxication. The ALDH2-associated change in peripheral glutamic acid (Glu) and gamma-aminobutyric acid (GABA) levels and its correlation with pharmacokinetics and psychomotor function remain unclear. In this study, ALDH2*2 mice were used to build an acute alcohol intoxication model after intraperitoneal administration. The blood ethanol and acetaldehyde concentrations were analyzed to generate concentration-time curves at two doses of alcohol (2.0 and 4.0 g/kg). The dose of 4.0 g/kg was selected in accordance with the preliminary behavioral evaluation result to perform the following behavioral tests (e.g. the rotarod test, the open field test, and the Y-maze test), so as to assess locomotor activity, anxiety and cognitive ability. Plasma Glu and GABA levels were determined through enzyme-linked immunosorbent assays. The results suggested that the ALDH2*2 mice had highly accumulated acetaldehyde levels, impaired locomotor activity and anxiety-like emotion but unimpaired cognitive function, compared to the wild type (WT) mice. The plasma Glu level and the ratio of Glu/GABA in the alcohol-treated WT and ALDH2*2 groups decreased from 2 to 5 h after intraperitoneal administration, whereas the GABA level did not change significantly. The blood alcohol concentration in the WT and ALDH2*2 mice was positively correlated with plasma Glu level, whereas the blood acetaldehyde level was found as the opposite. We speculate that the decline degree of Glu/GABA ratio could be associated with psychomotor retardation and needs to be further investigated.

Highly selective and sensitive detection of glutamate by an electrochemical aptasensor.

An electrochemical aptamer-based sensor was developed for glutamate, the major excitatory neurotransmitter in the central nervous system. Determining glutamic acid release and glutamic acid levels is crucial for studying signal transmission and for diagnosing pathological conditions in the brain. Glutamic acid-selective oligonucleotides were isolated from an ssDNA library using the Capture-SELEX protocol in complex medium. The selection permitted the isolation of an aptamer 1d04 with a dissociation constant of 12 µM. The aptamer sequence was further used in the development of an electrochemical aptamer sensor. For this purpose, a truncated aptamer sequence named glu1 was labelled with a ferrocene redox tag at the 3'-end and immobilized on a gold electrode surface via Au-thiol bonds. Using 6-mercapto-1-hexanol as the backfill, the sensor performance was characterized by alternating current voltammetry. The glu1 aptasensor showed a limit of detection of 0.0013 pM, a wide detection range between 0.01 pM and 1 nM, and good selectivity for glutamate in tenfold diluted human serum. With this enzyme-free aptasensor, the highly selective and sensitive detection of glutamate was demonstrated, which possesses great potential for implementation in microelectrodes and for in vitro as well as in vivo monitoring of neurotransmitter release.

TAT delivery of a PTEN peptide inhibitor has direct cardioprotective effects and improves outcomes in rodent models of cardiac arrest.

We have recently shown that pharmacologic inhibition of PTEN significantly increases cardiac arrest survival in a mouse model, however, this protection required pretreatment 30 min before the arrest. To improve the onset of PTEN inhibition during cardiac arrest treatment, we have designed a TAT fused cell-permeable peptide (TAT-PTEN9c) based on the C-terminal PDZ binding motif of PTEN for rapid tissue delivery and protection. Western blot analysis demonstrated that TAT-PTEN9c peptide significantly enhanced Akt activation in mouse cardiomyocytes in a concentration- and time-dependent manner. Mice were subjected to 8 min asystolic arrest followed by CPR, and 30 mice with successful CPR were then randomly assigned to receive either saline or TAT-PTEN9c treatment. Survival was significantly increased in TAT-PTEN9c-treated mice compared with that of saline control at 4 h after CPR. The treated mice had increased Akt phosphorylation at 30 min resuscitation with significantly decreased sorbitol content in heart or brain tissues and reduced release of taurine and glutamate in blood, suggesting improved glucose metabolism. In an isolated rat heart Langendorff model, direct effects of TAT-PTEN9c on cardiac function were measured for 20 min following 20 min global ischemia. Rate pressure product was reduced by >20% for both TAT vehicle and nontreatment groups following arrest. Cardiac contractile function was completely recovered with TAT-PTEN9c treatment given at the start of reperfusion. We conclude that TAT-PTEN9c enhances Akt activation and decreases glucose shunting to the polyol pathway in critical organs, thereby preventing osmotic injury and early cardiovascular collapse and death.NEW & NOTEWORTHY We have designed a cell-permeable peptide, TAT-PTEN9c, to improve cardiac arrest survival. It blocked endogenous PTEN binding to its adaptor and enhanced Akt signaling in mouse cardiomyocytes. It improved mouse survival after cardiac arrest, which is related to improved glucose metabolism and reduced glucose shunting to sorbitol in critical organs.

Liver mitochondrial DNA damage and genetic variability of Cytochrome b - a key component of the respirasome - drive the severity of fatty liver disease.

BACKGROUND AND AIMS: The progression of nonalcoholic fatty liver disease (NAFLD) into severe histological forms (steatohepatitis - NASH) is paralleled by the occurrence of complex molecular processes. Mitochondrial dysfunction is a hallmark feature of advanced disease. Mitochondrially encoded cytochrome B (cytochrome b, MT-CYB), a member of the oxidative phosphorylation system, is a key component of the respirasome supercomplex. Here, we hypothesized that NAFLD severity is associated with liver tissue cytochrome b mutations and damaged mitochondrial DNA (mtDNA). METHODS: We included 252 liver specimens of NAFLD patients - in whom histological disease ranged from mild to severe - which were linked to clinical and biochemical information. Tissue molecular explorations included MT-CYB sequencing and analysis of differential mtDNA damage. Profiling of circulating Krebs cycle metabolites and global liver transcriptome was performed in a subsample of patients. Tissue levels of 4-hydroxynonenal - a product of lipid peroxidation and 8-hydroxy-2'-deoxyguanosine, a marker of oxidative damage - were measured. RESULTS: Compared to simple steatosis, NASH is associated with a higher level of MT-CYB variance, 12.1 vs. 15.6 substitutions per 103  bp (P = 5.5e-10). The burden of variants was associated with increased levels of 2-hydroxyglutarate, branched-chain amino acids, and glutamate, and changes in the global liver transcriptome. Liver mtDNA damage was associated with advanced disease and inflammation. NAFLD severity was associated with increased tissue levels of DNA oxidative adducts and lipid peroxyl radicals. CONCLUSION: NASH is associated with genetic alterations of the liver cellular respirasome, including high cytochrome b variation and mtDNA damage, which may result in broad cellular effects.

Effective glutamate clearance from the systemic circulation by hemodialysis: Potential relevance for cerebral ischemia management.

High glutamate levels after head trauma or cerebral ischemia have neurotoxic effects. The objective of the present study was to evaluate the efficacy of hemodialysis to remove glutamate from the blood and to assess the behavior of this small molecule. Ten patients with end-renal disease on hemodialysis were included in the study. Glutamate clearance was evaluated within the first hour of hemodialysis on a midweek dialysis day on five patients who underwent low flux hemodialysis, whereas the other five patients underwent highly efficient hemodialysis (high flux hemodialysis on one day and online hemodiafiltration on another day). Glutamate clearance with hemodialysis was very effective and did not show any differences between the techniques (low flux: 214 [55], high flux: 204 [37], online hemodiafiltration: 202 [16], median (interquartile range), P = .7). Glutamate clearance was almost equivalent to vascular access plasma flow and it was not affected by dialyzer permeability or ultrafiltration rate. After a hemodialysis session, a significant decrease in glutamate blood level was observed (prehemodialysis: 59.7 [36.1], posthemodialysis 37.0 [49.2], P = .005). Dialysis performed under fasting condition showed higher glutamate reduction rate (60%) than that under feeding condition (20%). Hemodialysis may be an effective method to reduce glutamate blood levels, and the molecule clearance does not differ between the different techniques used. Considering previous results in experimental models, hemodialysis without hemodynamic stress, could be considered for reducing glutamate neurotoxic effects in acute ischemic strokes of patients in chronic hemodialysis programs.

Analysis of Serum Metabolomics in Rats with Osteoarthritis by Mass Spectrometry.

Osteoarthritis is a common multifactorial chronic disease that occurs in articular cartilage, subchondral bone, and periarticular tissue. The pathogenesis of OA is still unclear. To investigate the differences in serum metabolites between OA and the control group, liquid chromatography/mass spectrometry (LC/MS)-based metabolomics was used. To reveal the pathogenesis of OA, 12 SD male rats were randomly divided into control and OA groups using collagenase to induce OA for modeling, and serum was collected 7 days after modeling for testing. The OA group was distinguished from the control group by principal component analysis and orthogonal partial least squares-discriminant analysis, and six biomarkers were finally identified. These biomarkers were metabolized through tryptophan metabolism, glutamate metabolism, nitrogen metabolism, spermidine metabolism, and fatty acid metabolism pathways. The study identified metabolites that may be altered in OA, suggesting a role in OA through relevant metabolic pathways. Metabolomics, as an important tool for studying disease mechanisms, provides useful information for studying the metabolic mechanisms of OA.

Correlation of Antibodies to Neurotransmitters in the Sera of Women with Alcohol Dependence and Depressive Disorders.

Comparative analysis of blood sera from women with alcohol dependence and depressive disorders or from conditionally healthy women revealed reduced level of antibodies to dopamine, norepinephrine, serotonin, glutamate, and GABA in blood serum in women with dysthymic disorder and a depressive episode and their increased content in women with alcohol dependence in combination with depressive disorders.

High Plasma Glutamate and a Low Glutamine-to-Glutamate Ratio Are Associated with Increased Risk of Heart Failure but Not Atrial Fibrillation in the Prevención con Dieta Mediterránea (PREDIMED) Study.

BACKGROUND: Although the association between glutamate and glutamine in relation to cardiometabolic disorders has been evaluated, the role of these metabolites in the development of atrial fibrillation (AF) and heart failure (HF) remains unknown. OBJECTIVES: We examined associations of glutamate, glutamine, and the glutamine-to-glutamate ratio with AF and HF incidence in a Mediterranean population at high cardiovascular disease (CVD) risk. METHODS: The present study used 2 nested case-control studies within the PREDIMED (Prevención con Dieta Mediterránea) study. During ∼10 y of follow-up, there were 509 AF incident cases matched to 618 controls and 326 HF incident cases matched to 426 controls. Plasma concentrations of glutamate and glutamine were semiquantitatively profiled with LC-tandem MS. ORs were estimated with multivariable conditional logistic regression models. RESULTS: In fully adjusted models, per 1-SD increment, glutamate was associated with a 29% (95% CI: 1.08, 1.54) increased risk of HF and glutamine-to-glutamate ratio with a 20% (95% CI: 0.67, 0.94) decreased risk. Glutamine-to-glutamate ratio was also inversely associated with HF risk (OR per 1-SD increment: 0.80; 95% CI: 0.67, 0.94) when comparing extreme quartiles. Higher glutamate concentrations were associated with a worse cardiometabolic risk profile, whereas a higher glutamine-to-glutamate ratio was associated with a better cardiometabolic risk profile. No associations between the concentrations of these metabolites and AF were observed. CONCLUSIONS: Our findings suggest that high plasma glutamate concentrations possibly resulting from alterations in the glutamate-glutamine cycle may contribute to the development of HF in Mediterranean individuals at high CVD risk.This trial was registered at www.isrctn.com as ISRCTN35739639.

Highly Sensitive and Selective Luminescence Sensor Based on Two-Fold Interpenetrated MOFs for Detecting Glutamate in Serum.

Glutamate is a biomarker for many nervous system diseases, and sensitively detecting glutamate is meaningful in the clinic. Therefore, a unique 3D framework of Cd-MOF (1) is synthesized and characterized. A single-crystal X-ray study reveals that it is a two-fold interpenetration (4,4)-connected framework with a PtS topology, where a large 1D rhombic channel with a size of 8 × 14 Å exists and the total potential void volume can reach 62%. Luminescence results demonstrate that 1 has good luminescence stability and can sensitively detect glutamate in water with a detection limit of 1.15 × 10-7 mol/L, which makes it the most sensitive MOF-based luminescence sensor of glutamate to date. More importantly, it also can serve as a luminescence sensor to detect glutamate in serum, and the quenching concentration needs to be only 43.1 µmol/L, which is much lower than the harmful level of glutamate (400 µmol/L) in glioma patients' blood. Compound 1 can be used at least five cycles. These results show that 1 has a potential application in monitoring glutamate in clinical scenarios.

Highly Stable Lanthanide Metal-Organic Framework as an Internal Calibrated Luminescent Sensor for Glutamic Acid, a Neuropathy Biomarker.

Glutamic acid (Glu) is the most abundant excitatory neurotransmitter in the central nervous system, and an elevated level of Glu may indicate some neuropathological diseases. Herein, three isomorphic microporous lanthanide metal-organic frameworks (MOFs) [(CH3)2NH2]2[Ln6(µ3-OH)8(BDC-OH)6(H2O)6]·(solv)x (ZJU-168; ZJU = Zhejiang University, H2BDC-OH = 2-hydroxyterephthalic acid, Ln = Eu, Tb, Gd) were designed for the detection of Glu. ZJU-168(Eu) and ZJU-168(Tb) suspensions simultaneously produce the characteristic emission bands of both lanthanide ions and ligands. When ZJU-168(Eu) and ZJU-168(Tb) suspensions exposed to Glu, the fluorescence intensity of ligands increases while the emission of lanthanide ions is almost unchanged. By utilizing the emission of ligands as the detected signal and the emission of lanthanide ions as the internal reference, an internal calibrated fluorescence sensor for Glu was obtained. There is a good linear relationship between fluorescence intensity ratio and Glu concentration in a wide range with the detection limit of 3.6 µM for ZJU-168(Tb) and 4.3 µM for ZJU-168(Eu). Major compounds present in blood plasma have no interference for the detection of Glu. Furthermore, a convenient analytical device based on a one-to-two logic gate was constructed for monitoring Glu. These establish ZJU-168(Tb) as a potential turn-on, ratiometric, and colorimetric fluorescent sensor for practical detection of Glu.

Brain to blood efflux as a mechanism underlying the neuroprotection mediated by rapid remote preconditioning in brain ischemia.

Glutamate represents the main excitatory neurotransmitter in the mammalian brain; however, its excessive elevation in the extracellular space is cytotoxic and can result in neuronal death. The ischemia initiated brain damage reflects changes in glutamate concentration in peripheral blood. This paper investigated the role of the brain in blood efflux of the glutamate in an improved tolerance of the brain tissue to ischemic conditions. In the rat model of focal brain ischemia, the neuroprotection was initiated by rapid remote ischemic preconditioning (rRIPC). Our results confirmed a strong neuroprotective effect of rRIPC. We observed reduced infarction by about 78% related to improved neuronal survival by about 70% in the ischemic core. The level of tissue glutamate in core and penumbra dropped significantly and decreased to control value also in the core region of the contralateral hemisphere. Despite significant improvement of blood-brain barrier integrity (by about 76%), the additional gain of glutamate content in the peripheral blood was caused by rRIPC. Based on our results, we can assume that neuroprotection mediated by rapid remote ischemic preconditioning could lie in the regulated, whole-brain release of glutamate from nerve tissue to the blood, which preserves neurons from the exposure to glutamate toxicity and results in reduced infarction.

Altered amino acid concentrations in NAFLD: Impact of obesity and insulin resistance.

Plasma concentrations of amino acids (AAs), in particular, branched chain AAs (BCAAs), are often found increased in nonalcoholic fatty liver disease (NAFLD); however, if this is due to increased muscular protein catabolism, obesity, and/or increased insulin resistance (IR) or impaired tissue metabolism is unknown. Thus, we evaluated a) if subjects with NAFLD without obesity (NAFLD-NO) compared to those with obesity (NAFLD-Ob) display altered plasma AAs compared to controls (CTs); and b) if AA concentrations are associated with IR and liver histology. Glutamic acid, serine, and glycine concentrations are known to be altered in NAFLD. Because these AAs are involved in glutathione synthesis, we hypothesized they might be related to the severity of NAFLD. We therefore measured the AA profile of 44 subjects with NAFLD without diabetes and who had a liver biopsy (29 NAFLD-NO and 15 NAFLD-Ob) and 20 CTs without obesity, by gas chromatography-mass spectrometry, homeostasis model assessment of insulin resistance, hepatic IR (Hep-IR; Hep-IR = endogenous glucose production × insulin), and the new glutamate-serine-glycine (GSG) index (glutamate/[serine + glycine]) and tested for an association with liver histology. Most AAs were increased only in NAFLD-Ob subjects. Only alanine, glutamate, isoleucine, and valine, but not leucine, were increased in NAFLD-NO subjects compared to CTs. Glutamate, tyrosine, and the GSG-index were correlated with Hep-IR. The GSG-index correlated with liver enzymes, in particular, gamma-glutamyltransferase (R = 0.70), independent of body mass index. Ballooning and/or inflammation at liver biopsy were associated with increased plasma BCAAs and aromatic AAs and were mildly associated with the GSG-index, while only the new GSG-index was able to discriminate fibrosis F3-4 from F0-2 in this cohort. CONCLUSION: Increased plasma AA concentrations were observed mainly in subjects with obesity and NAFLD, likely as a consequence of increased IR and protein catabolism. The GSG-index is a possible marker of severity of liver disease independent of body mass index. (Hepatology 2018;67:145-158).

Clinical validation of blood/brain glutamate grabbing in acute ischemic stroke.

OBJECTIVE: Blood/brain-glutamate grabbing is an emerging concept in the treatment of acute ischemic stroke, where essentially the deleterious effects of glutamate after ischemia are ameliorated by coaxing glutamate to enter the bloodstream and thus reducing its concentration in the brain. Aiming to demonstrate the clinical efficacy of blood glutamate grabbers in patients with stroke, in this study, we resorted to a drug-repositioning strategy for the discovery of new glutamate-grabbing drugs. METHODS: The glutamate-grabbing ability of 1,120 compounds (90% of which were drugs approved by the US Food and Drug Administration) was evaluated during an in vitro high-throughput screening campaign. Subsequently, the protective efficacy of the selected drugs was probed in an ischemic animal model and finally tested in stroke patients. RESULTS: Riboflavin (vitamin B2 ) was identified as the main hit compound. In ischemic animal models treated with riboflavin (1mg/kg), it was confirmed that blood glutamate reduction was associated with a significant reduction of infarct size. These results led to a randomized, double-blind, phase IIb clinical trial with patients with stroke. Fifty patients were randomized to 1 of the 2 study arms: the control group (placebo) and the experimental group (20mg of riboflavin [vitamin B2 Streuli@ ). Decrease in glutamate concentration was significantly greater (p < 0.029) in the treated group. Comparative analysis of the percentage improvement on the National Institutes of Health Stroke Scale score at discharge was slightly higher in the riboflavin-treated group than in the placebo group (33.7 ± 43.7 vs 48.9 ± 42.4%, p = 0.050). INTERPRETATION: This translational study represents the first human demonstration of the efficacy of blood glutamate grabbers in the treatment of patients with stroke, paving the way for the development of a promising novel protective therapy. Ann Neurol 2018;84:260-273.

Association between serum haptoglobin and carotid arterial functions: usefulness of a targeted metabolomics approach.

BACKGROUND: Serum haptoglobin (Hp) has been closely associated with cardio-cerebrovascular diseases. We investigated a metabolic profile associated with circulating Hp and carotid arterial functions via a targeted metabolomics approach to provide insight into potential mechanisms. METHODS: A total of 240 participants, including 120 patients with type 2 diabetes mellitus (T2DM) and 120 non-diabetes mellitus (non-DM) subjects were recruited in this study. Targeted metabolic profiles of serum metabolites were determined using an AbsoluteIDQ™ p180 Kit (BIOCRATES Life Sciences AG, Innsbruck, Austria). Ultrasound of the bilateral common carotid artery was used to measure intima-media thickness and inter-adventitial diameter. Serum Hp levels were tested by enzyme-linked immunosorbent assay. RESULTS: Serum Hp levels in T2DM patients and non-DM subjects were 103.40 (72.46, 131.99) mg/dL and 100.20 (53.99, 140.66) mg/dL, respectively. Significant differences of 19 metabolites and 17 metabolites were found among serum Hp tertiles in T2DM patients and non-DM subjects, respectively (P < 0.05). Of these, phosphatidylcholine acyl-alkyl C32:2 (PC ae C32:2) was the common metabolite observed in two populations, which was associated with the serum Hp groups and lipid traits (P < 0.05). Furthermore, the metabolite ratios of two acidic amino acids, including aspartate to PC ae C32:2 (Asp/PC ae C32:2) and glutamate to PC ae C32:2 (Glu/PC ae C32:2) were correlated with serum Hp, carotid arterial functions and other biochemical index in both populations significantly (P < 0.05). CONCLUSIONS: Targeted metabolomics analyses might provide a new insight into the potential mechanisms underlying the association between serum Hp and carotid arterial functions.

Alteration in NMDAR-related amino acids in first episode psychosis.

The aim of the present study was to explore the role of N-methyl-D-aspartate receptor (NMDAR) related amino acids in drug-naive first episode psychosis (FEP) patients. The medication naïve patients with FEP (n = 40) and healthy volunteers with no family history of schizophrenia (n = 35) were recruited to the study and followed up for 10 weeks. Liquid chromatography-mass spectrometry method was used to measure plasma levels of the amino acids. The plasma glutamine, glutamic acid, proline, serine, asparagine, and hydroxyproline levels were significantly higher in the FEP patients compared to healthy controls (p values < .0001). The glutamine/glutamic acid ratio in FEP patients was not different from the healthy controls (p > .05). After the antipsychotic treatment, plasma glutamic acid, proline, and hydroxyproline levels were significantly increased (p values < .05) while the asparagine level and glutamine/glutamic acid ratio were decreased (p values < .05). The serine and glutamine levels did not show any differences with the treatment (p > .05). The initial plasma glutamine levels were negatively correlated with the initial Scale for the Assessment of Positive Symptoms (SAPS) score (r = -.45, p = .003). The initial plasma proline levels were negatively correlated with the initial and follow-up SAPS scores (r = -.51 and -.39, p values < .05). The initial plasma proline and hydroxyproline levels were both negatively correlated with the initial Brief Psychiatric Rating Scale score (r = -.37, p = .017 and r = -.33, p = .033, respectively). Increase in NMDAR-related amino acid levels during the FEP may be a compensatory response to glutamatergic hypofunction. Their plasma levels were significantly correlated with several psychotic symptoms before and after 10-week treatment. Antipsychotic treatment has differential effects on the plasma levels of these amino acids.

Circulating glutamate level as a potential biomarker for abdominal obesity and metabolic risk.

BACKGROUND AND AIM: Circulating level of glutamate, a by-product of the catabolism of branched-chain amino acids, has been positively correlated with visceral adipose tissue accumulation and waist circumference (WC). The aim of the present study was to assess the potential of using glutamate level to identify individuals with abdominal obesity and a high cardiometabolic risk. METHODS AND RESULTS: The study sample included 99 men and 99 women. Fasting serum glutamate was measured using the Biocrates p180 kit. Anthropometric and metabolic variables were used to identify individuals with abdominal obesity (WC ≥ 95 cm in both sexes), the hypertriglyceridemic waist (HTW) phenotype and the metabolic syndrome (MetS). Mean (±SD) age was 34.1 ± 10.1 years, mean BMI was 29.0 ± 6.2 kg/m2 and mean WC was 92.7 ± 16.5 cm. Glutamate was strongly correlated with WC (r = 0.66 for men; r = 0.76 for women, both p < 0.0001) and multiple markers of metabolic dysfunction, particularly fasting triglyceride level (r = 0.59 for men; r = 0.57 for women, both p < 0.0001), HDL-cholesterol level (r = -0.45, p < 0.0001 in both sexes) and the HOMA-IR index (r = 0.65 for men; r = 0.60 for women, both p < 0.0001). Logistic regressions showed that glutamate had an excellent accuracy to identify individuals with abdominal obesity (ROC_AUC: 0.90 for both sexes), a good accuracy to identify those with the HTW phenotype (ROC_AUC: 0.82 for men; 0.85 for women) and fair-to-good accuracy for the MetS (ROC_AUC: 0.78 for men; 0.89 for women). CONCLUSION: Glutamate level may represent an interesting potential biomarker of abdominal obesity and metabolic risk.

High plasma glutamate and low glutamine-to-glutamate ratio are associated with type 2 diabetes: Case-cohort study within the PREDIMED trial.

BACKGROUND AND AIMS: Glutamate, glutamine are involved in energy metabolism, and have been related to cardiometabolic disorders. However, their roles in the development of type-2 diabetes (T2D) remain unclear. The aim of this study was to examine the effects of Mediterranean diet on associations between glutamine, glutamate, glutamine-to-glutamate ratio, and risk of new-onset T2D in a Spanish population at high risk for cardiovascular disease (CVD). METHODS AND RESULTS: The present study was built within the PREDIMED trial using a case-cohort design including 892 participants with 251 incident T2D cases and 641 non-cases. Participants (mean age 66.3 years; female 62.8%) were non diabetic and at high risk for CVD at baseline. Plasma levels of glutamine and glutamate were measured at baseline and after 1-year of intervention. Higher glutamate levels at baseline were associated with increased risk of T2D with a hazard ratio (HR) of 2.78 (95% CI, 1.43-5.41, P for trend = 0.0002). In contrast, baseline levels of glutamine (HR: 0.64, 95% CI, 0.36-1.12; P for trend = 0.04) and glutamine-to-glutamate ratio (HR: 0.31, 95% CI, 0.16-0.57; P for trend = 0.0001) were inversely associated with T2D risk when comparing extreme quartiles. The two Mediterranean diets (MedDiet + EVOO and MedDiet + mixed nuts) did not alter levels of glutamine and glutamate after intervention for 1 year. However, MedDiet mitigated the positive association between higher baseline plasma glutamate and T2D risk (P for interaction = 0.01). CONCLUSION: Higher levels of glutamate and lower levels of glutamine were associated with increased risk of T2D in a Spanish population at high risk for CVD. Mediterranean diet might mitigate the association between the imbalance of glutamine and glutamate and T2D risk. This trial is registered at http://www.controlled-trials.com, ISRCTN35739639.

Serum glutamate was elevated in children aged 3-10 years with autism spectrum disorders when they were compared with controls.

AIM: This study aimed to see whether measuring serum glutamate in children with autism spectrum disorder (ASD) could provide a biological marker that could allow early intervention. METHODS: Serum glutamate was measured in 30 patients aged 3-10 years presenting with ASD to the Abou El Reesh Hospitals, Cairo University, Egypt and 30 matched controls without ASD in 2015. The Vineland Social Maturity Scale was applied to assess social competence, self- help skills and adaptive behaviour in both groups. The severity of autism was measured with the Childhood Autism Rating Scale test. RESULTS: The patients' group showed higher mean values of serum glutamate (5.888) than the control group (2.521) and the statistical difference was significant (p = 0.00021). There was no significant difference (p = 0.151) in the serum level of glutamate between patients receiving 1-2 mg of risperidone (6.519 ± 2.851) and those who were free from any medication for at least six weeks (5.157 ± 2.184). CONCLUSION: We found higher levels of serum glutamate in subjects with ASD and this might reflect altered glutamatergic neurotransmission which may aid early ASD detection. Further investigations are needed with a large number of participants to further clarify the possibility of using glutamate as a biomarker for ASD.

Leucine alone or in combination with glutamic acid, but not with arginine, increases biceps femoris muscle and alters muscle AA transport and concentrations in fattening pigs.

Forty-eight Duroc × Large White × Landrace pigs with an average initial body weight of 77.09 ± 1.37 kg were used to investigate the effects of combination of leucine (Leu) with arginine (Arg) or glutamic acid (Glu) on muscle growth, free amino acid profiles, expression levels of amino acid transporters and growth-related genes in skeletal muscle. The animals were randomly assigned to one of the four treatment groups (12 pigs/group, castrated male:female = 1:1). The pigs in the control group were fed a basal diet (13% Crude Protein), and those in the experimental groups were fed the basal diet supplemented with 1.00% Leu (L group), 1.00% Leu + 1.00% Arg (LA group) or 1.00% Leu + 1.00% Glu (LG group). The experiment lasted for 60 days. Results showed an increase (p < 0.05) in biceps femoris (BF) muscle weight in the L group and LG group relative to the basal diet group. In longissimus dorsi (LD) muscle, Lys, taurine and total essential amino acid concentration increased in the LG group relative to the basal diet group (p < 0.05). In LG group, Glu and carnosine concentrations increased (p < 0.05) in the BF muscle, when compared to the basal diet group. The Leu and Lys concentrations of BF muscle were lower in the LA group than that in the L group (p < 0.05). A positive association was found between BF muscle weight and Leu concentration (p < 0.05). The LG group presented higher (p < 0.05) mRNA levels of ASCT2, LAT1, PAT2, SANT2 and TAT1 in LD muscle than those in the basal diet group. The mRNA levels of PAT2 and MyoD in BF muscle were upregulated (p < 0.05) in the LG group, compared with those in the basal diet group. In conclusion, Leu alone or in combination with Glu is benefit for biceps femoris muscle growth in fattening pig.