mPEG-b-P(Glu-co-Phe) nanoparticles increase gastric retention time and gastric ulcer treatment efficacy of 20(S)-ginsenoside Rg3.

BACKGROUND: Gastric ulcer (GU) belongs to gastric mucosal irritation and damage. 20(S)-ginsenoside Rg3 (Rg3) has shown anti-oxidant, antiinflammation, and tissue repair effects which are essential for GU treatment. However, the solubility of Rg3 is poor and low gastrointestinal absorption may limit its anti-ulcer effects. As a result, we aim to increase the gastric retention time and gastric absorption of Rg3 to achieve better GU treatment efficacy. METHODS: The mPEG-b-P(Glu-co-Phe) nanoparticles loaded with Rg3 (Rg3-NPs) were developed. The characteristics of Rg3-NPs, including the morphology, diameter, and stability were analyzed. The Rg3 release profiles, gastric retention of Rg3, in vitro cytotoxicity, and pharmacokinetics of Rg3 were assessed. An alcohol-induced rats GU model was performed, and the rats were randomly separated into five treatment groups. Biochemical analysis, gross evaluation, histopathology, and immunohistochemical analysis were applied to further analyze the anti-ulcer effects of Rg3-NPs. RESULTS: Rg3-NPs were successfully prepared and the Rg3 release was pH sensitive. The gastric retention time of Rg3 is longer in Rg3-NPs group than that in Rg3 group. By slightly increasing nitric oxide (NO), obviously increasing epidermal growth factor (EGF), EGF receptor (EGFR), and superoxide dismutase (SOD), and decreasing endothelin-1 (ET-1) and nitric oxide synthase (NOS2), Rg3-NPs possess better GU treatment efficacy than Rg3. CONCLUSIONS: Rg3-NPs can increase gastric retention time and gastric absorption of Rg3 and promote its GU treatment efficacy.

Myelin-associated glycoprotein activation triggers glutamate uptake by oligodendrocytes in vitro and contributes to ameliorate glutamate-mediated toxicity in vivo.

BACKGROUND: Myelin-associated glycoprotein (MAG) is a key molecule involved in the nurturing effect of myelin on ensheathed axons. MAG also inhibits axon outgrowth after injury. In preclinical stroke models, administration of a function-blocking anti-MAG monoclonal antibody (mAb) aimed to improve axon regeneration demonstrated reduced lesion volumes and a rapid clinical improvement, suggesting a mechanism of immediate neuroprotection rather than enhanced axon regeneration. In addition, it has been reported that antibody-mediated crosslinking of MAG can protect oligodendrocytes (OLs) against glutamate (Glu) overload by unknown mechanisms. PURPOSE: To unravel the molecular mechanisms underlying the protective effect of anti-MAG therapy with a focus on neuroprotection against Glu toxicity. RESULTS: MAG activation (via antibody crosslinking) triggered the clearance of extracellular Glu by its uptake into OLs via high affinity excitatory amino acid transporters. This resulted not only in protection of OLs but also nearby neurons. MAG activation led to a PKC-dependent activation of factor Nrf2 (nuclear-erythroid related factor-2) leading to antioxidant responses including increased mRNA expression of metabolic enzymes from the glutathione biosynthetic pathway and the regulatory chain of cystine/Glu antiporter system xc- increasing reduced glutathione (GSH), the main antioxidant in cells. The efficacy of early anti-MAG mAb administration was demonstrated in a preclinical model of excitotoxicity induced by intrastriatal Glu administration and extended to a model of Experimental Autoimmune Encephalitis showing axonal damage secondary to demyelination. CONCLUSIONS: MAG activation triggers Glu uptake into OLs under conditions of Glu overload and induces a robust protective antioxidant response.

Poly(L-Glutamic Acid)-Based Brush Copolymers: Fabrication, Self-assembly, and Evaluation as Efficient Nanocarriers for Cationic Protein Drug Delivery.

Protein drugs were considered to be the first choice to treat many human diseases, but their clinical application was usually limited by their short half-life and lack of validated targeted therapy. Here, a series of folate-functionalized poly(ethylene glycol)-b-(poly(2-aminoethyl-L-glutamate)-g-poly(L-glutamic acid))s (FA-PEG-b-(PELG-g-PLGA)s) were designed as tumor-targeted carriers for cationic protein delivery. Compared with traditional copolymers consisting of PEG and linear charged hydrophilic blocks, FA-PEG-b-(PELG-g-PLGA) with brush-like polyelectrolyte segments were beneficial to improving their electrostatic interactions with loading protein molecules, thus increasing drug-loading stability and protecting encapsulated proteins from degradation. The designed polymer brushes could efficiently encapsulate cytochrome C (CytC), a cationic model protein, to form polyion complex (PIC) micelles with an average particle size of approximately 200 nm. An in vitro drug release study showed that the drug-loading stability of the formed PIC micelles was largely improved. The functionalization of the block copolymer carriers with a targeting folate group enhanced the tumor cell growth inhibition and total apoptotic rates induced by CytC. Our results shed light on the unique advantages of brush-like polymer carriers in delivering cationic proteins, and the poly(L-glutamic acid)-based linear-brush diblock copolymers could be applied as a versatile delivery platform for molecular targeting in cancer therapy.

Propofol exerts neuroprotective functions by down-regulating microRNA-19a in glutamic acid-induced PC12 cells.

BACKGROUND: Propofol, a kind of intravenous sedative drug, is certified that exerts anti-inflammation and antitumor functions. However, the influence of propofol in cerebral injury and the corresponding mechanism remains unexplained, that our article focuses on. METHODS: PC12 cells were treated with propofol and exposed in glutamic acid (Glu) solutions. Cell viability, apoptotic potential, apoptosis-related and autophagy-linked proteins were tested via CCK-8, flow cytometry, and western blot assays. Reverse transcription-quantitative real-time PCR was utilized to test miR-19a expression in Glu-stimulated cells. Next, miR-19a mimic transfection was used to assess the effects of miR-19a on cell apoptosis and autophagy in Glu or propofol treated cells. Finally, western blot was performed to test AMPK and mTOR pathways. RESULTS: Glu exposure promoted cell apoptosis and autophagy of PC12 cells, while propofol attenuated cell apoptosis and autophagy triggered by Glu. Additionally, propofol decreased the miR-19a expression in Glu-stimulated PC12 cells. Meanwhile, over-expression of miR-19a reversed the effects of propofol on Glu-induced cell apoptosis and autophagy. Moreover, propofol potentiated AMPK and mTOR pathways in Glu-stimulated PC12 cells via impeding miR-19a expression. CONCLUSIONS: These finding revealed that propofol relieved Glu-triggered apoptosis and autophagy of PC12, and activated AMPK and mTOR pathways by suppressing miR-19a expression.

The selective BDNF overexpression in neurons protects neuroglial networks against OGD and glutamate-induced excitotoxicity.

Objective: Cerebral ischemia is accompanied by damage and death of a significant number of neurons due to glutamate excitotoxicity with subsequent a global increase of cytosolic Ca2+ concentration ([Ca2+]i). This study aimed to investigate the neuroprotective action of BDNF overexpression in hippocampal neurons against injury under ischemia-like conditions (oxygen and glucose deprivation) and glutamate-induced excitotoxicity (GluTox).Methods: The overexpression of BDNF was reached by the transduction of cell cultures with the adeno-associated (AAV)-Syn-BDNF-EGFP virus construct. Neuroprotective effects were mediated by Ca2+-dependent BDNF release followed by activation of the neuroprotective signaling cascades and changes of the gene expression. Thus, BDNF overexpression modulates Ca2+ homeostasis in cells, preventing Ca2+ overload and initiation of apoptotic and necrotic processes.Results:Antiapoptotic effect of BDNF overexpression is mediated via activation of phosphoinositide-3-kinase (PI3K) pathway and changing the expression of PI3K, HIF-1, Src and an anti-inflammatory cytokine IL-10. On the contrary, the decrease of expression of proapoptotic proteins such as Jun, Mapk8, caspase-3 and an inflammatory cytokine IL-1ß was observed. These changes of expression were accompanied by the decrease of quantity of IL-1ß receptors and the level of TNFα in cells in control, as well as 24 h after OGD. Besides, BDNF overexpression changes the expression of GABA(B) receptors. Also, the expression of NMDA and AMPA receptor subunits was altered towards a change in the conductivity of the receptors for Ca2+.Conclusion: Thus, our results demonstrate that neuronal BDNF overexpression reveals complex neuroprotective effects on the neurons and astrocytes under OGD and GluTox via inhibition of Ca2+ responses and regulation of gene expression.

Dosimetry of 177Lu-PSMA-617 after Mannitol Infusion and Glutamate Tablet Administration: Preliminary Results of EUDRACT/RSO 2016-002732-32 IRST Protocol.

Radio-ligand therapy (RLT) with177Lu-PSMA-617 is a promising option for patients with metastatic castration-resistant prostate-cancer (mCRPC). A prospective phase-II study (EUDRACT/RSO,2016-002732-32) on mCRPC is ongoing at IRST (Meldola, Italy). A total of 9 patients (median age: 68 y, range: 53⁻85) were enrolled for dosimetry evaluation of parotid glands (PGs), kidneys, red marrow (RM) and whole body (WB). Folic polyglutamate tablets were orally administered as PGs protectors and 500 mL of a 10% mannitol solution was intravenously infused to reduce kidney uptake. The whole body planar image (WBI) and blood samples were acquired at different times post infusion (1 h, 16⁻24 h, 36⁻48 h and 120 h). Dose calculation was performed with MIRD formalism (OLINDA/EXM software). The median effective half-life was 33.0 h (range: 25.6⁻60.7) for PGs, 31.4 h (12.2⁻80.6) for kidneys, 8.2 h (2.5⁻14.7) for RM and 40.1 h (31.6⁻79.7) for WB. The median doses were 0.48 mGy/MBq (range: 0.33⁻2.63) for PGs, 0.70 mGy/MBq (0.26⁻1.07) for kidneys, 0.044 mGy/MBq (0.023⁻0.067) for RM and 0.04 mGy/MBq (0.02⁻0.11) for WB. A comparison with previously published dosimetric data was performed and a significant difference was found for PGs while no significant difference was observed for the kidneys. For PGs, the possibility of reducing uptake by administering glutamate tablets during RLT seems feasible while further research is warranted for a more focused evaluation of the reduction in kidney uptake.

In vitro cellular localization and efficient accumulation of fluorescently tagged biomaterials from monodispersed chitosan nanoparticles for elucidation of controlled release pathways for drug delivery systems.

BACKGROUND: Inefficient cellular delivery and poor intracellular accumulation are major drawbacks towards achieving favorable therapeutic responses from many therapeutic drugs and biomolecules. To tackle this issue, nanoparticle-mediated delivery vectors have been aptly explored as a promising delivery strategy capable of enhancing the cellular localization of biomolecules and improve their therapeutic efficacies. However, the dynamics of intracellular biomolecule release and accumulation from such nanoparticle systems has currently remained scarcely studied. OBJECTIVES: The objective of this study was to utilize a chitosan-based nanoparticle system as the delivery carrier for glutamic acid, a model for encapsulated biomolecules to visualize the in vitro release and accumulation of the encapsulated glutamic acid from chitosan nanoparticle (CNP) systems. METHODS: CNP was synthesized via ionic gelation routes utilizing tripolyphosphate (TPP) as a cross-linker. In order to track glutamic acid release, the glutamic acid was fluorescently-labeled with fluorescein isothiocyanate prior encapsulation into CNP. RESULTS: Light Scattering data concluded the successful formation of small-sized and mono-dispersed CNP at a specific volume ratio of chitosan to TPP. Encapsulation of glutamic acid as a model cargo into CNP led to an increase in particle size to >100 nm. The synthesized CNP exhibited spherical shape under Electron Microscopy. The formation of CNP was reflected by the reduction in free amine groups of chitosan following ionic crosslinking reactions. The encapsulation of glutamic acid was further confirmed by Fourier Transform Infrared (FTIR) analysis. Cell viability assay showed 70% cell viability at the maximum concentration of 0.5 mg/mL CS and 0.7 mg/mL TPP used, indicating the low inherent toxicity property of this system. In vitro release study using fluorescently-tagged glutamic acids demonstrated the release and accumulation of the encapsulated glutamic acids at 6 hours post treatment. A significant accumulation was observed at 24 hours and 48 hours later. Flow cytometry data demonstrated a gradual increase in intracellular fluorescence signal from 30 minutes to 48 hours post treatment with fluorescently-labeled glutamic acids encapsulated CNP. CONCLUSION: These results therefore suggested the potential of CNP system towards enhancing the intracellular delivery and release of the encapsulated glutamic acids. This CNP system thus may serves as a potential candidate vector capable to improve the therapeutic efficacy for drugs and biomolecules in medical as well as pharmaceutical applications through the enhanced intracellular release and accumulation of the encapsulated cargo.

NBCe1 mediates the regulation of the NADH/NAD+ redox state in cortical astrocytes by neuronal signals.

Astrocytes are a glial cell type, which is indispensable for brain energy metabolism. Within cells, the NADH/NAD+ redox state is a crucial node in metabolism connecting catabolic pathways to oxidative phosphorylation and ATP production in mitochondria. To characterize the dynamics of the intracellular NADH/NAD+ redox state in cortical astrocytes Peredox, a genetically encoded sensor for the NADH/NAD+ redox state, was expressed in cultured cortical astrocytes as well as in cortical astrocytes in acutely isolated brain slices. Calibration of the sensor in cultured astrocytes revealed a mean basal cytosolic NADH/NAD+ redox ratio of about 0.01; however, with a broad distribution and heterogeneity in the cell population, which was mirrored by a heterogeneous basal cellular concentration of lactate. Inhibition of glucose uptake decreased the NADH/NAD+ redox state while inhibition of lactate dehydrogenase or of lactate release resulted in an increase in the NADH/NAD+ redox ratio. Furthermore, the NADH/NAD+ redox state was regulated by the extracellular concentration of K+ , and application of the neurotransmitters ATP or glutamate increased the NADH/NAD+ redox state dependent on purinergic receptors and glutamate uptake, respectively. This regulation by K+ , ATP, and glutamate involved NBCe1 mediated sodium-bicarbonate transport. These results demonstrate that the NADH/NAD+ redox state in astrocytes is a metabolic node regulated by neuronal signals reflecting physiological activity, most likely contributing to adjust astrocytic metabolism to energy demand of the brain.

The presence of glutamate residues on the PAS sequence of the stimuli-sensitive nano-ferritin improves in vivo biodistribution and mitoxantrone encapsulation homogeneity.

A genetically engineered human ferritin heavy chain (HFt)-based construct has been recently shown by our group to efficiently entrap and deliver doxorubicin to cancer cells. This construct, named HFt-MP-PAS, contained a tumor-selective sequence (MP) responsive to proteolytic cleavage by tumor proteases (MMPs), located between each HFt subunit and an outer shielding polypeptide sequence rich in proline (P), serine (S) and alanine (A) residues (PAS). HFt-MP-PAS displayed excellent therapeutic efficacy in xenogenic pancreatic and head and neck cancer models in vivo, leading to a significant increase in overall animal survivals. Here we report a new construct obtained by the genetic insertion of two glutamate residues in the PAS sequence of HFt-MP-PAS. Such new construct, named HFt-MP-PASE, is characterized by improved performances as drug biodistribution in a xenogenic pancreatic cancer model in vivo. Moreover, HFt-MP-PASE efficiently encapsulates the anti-cancer drug mitoxantrone (MIT), and the resulting MIT-loaded nanoparticles proved to be more soluble and monodispersed than the HFt-MP-PAS counterparts. Importantly, in vitro MIT-loaded HFt-MP-PASE kills several cancer cell lines of different origin (colon, breast, sarcoma and pancreas) at least as efficiently as the free drug. Finally, our MIT loaded protein nanocages allowed in vivo an impressive incrementing of the drug accumulation in the tumor with respect to the free drug.

A dose-response study of glutamate supplementation in isolated, perfused rat hearts undergoing ischaemia and cold cardioplegia.

OBJECTIVES: Several studies have reported superior post-cardioplegic recovery after glutamate supplementation. The optimum dose of glutamate supplementation is unknown. The purpose of this study was to find the optimal protective concentration of glutamate supplementation in a model of ischaemia/cardioplegia and reperfusion. METHODS: Isolated rat hearts (n = 77) were perfused with the Krebs-Henseleit buffer. After stabilization, the hearts were subjected to 25 min of normothermic ischaemia followed by a single 3-min infusion of cold (4-6 °C) St. Thomas' Hospital II cardioplegia and 87 min of cardioplegic ischaemic arrest and 60 min of reperfusion. Sodium-l-glutamate was added to the perfusate (control group had zero glutamate) in increasing concentrations (0.01, 0.1, 1, 10, 20, 30 and 100 mM) and given throughout perfusion. Corresponding concentrations were added to the cardioplegic solution. A balloon in the left ventricle inserted via the left atrium measured left ventricular pressures isometrically. Left ventricular developed pressure was calculated. Myocardial exchange of glucose and lactate was measured prior to ischaemia and during reperfusion. Myocardial content of glycogen and glutamate was measured at the end of reperfusion. RESULTS: During reperfusion left ventricular developed pressure increased (P < 0.0001) in groups supplemented with 0.1, 1.0, 10, 20 and 30 mM glutamate, whereas left ventricular end-diastolic pressure was attenuated (P = 0.008) when compared with the controls. No additional benefit on the continuous data left ventricular developed pressure and left ventricular end-diastolic pressure was observed with glutamate concentrations above 1 mM. Onset of LV pressure rise during the period of ischaemia was delayed by 100 mM of glutamate (P = 0.02). Myocardial content of glutamate was increased in a dose-related manner in Groups 10, 20, 30 and 100 compared with the control hearts (P < 0.0001). Glycogen was increased in the hearts supplemented with 100 mM of glutamate (P = 0.02). CONCLUSIONS: Even low concentrations of l-glutamate improved postischaemic and post-cardioplegic heart function and 1 mM seems to be optimal.

Influence of sexual behavior of Dorper rams treated with glutamate and/or testosterone on reproductive performance of anovulatory ewes.

The aim of this study was to determine if exogenous administration of glutamate and (or) testosterone to male rams during the season of reproductive arrest is able to re-activate male sexual behavior and, later on, to promote through the male effect, both sexual and reproductive competence of anovulatory nulliparous ewes. Therefore, an experiment was performed under long-day photoperiods (spring; photo-reproductive arrest, 26°N). Dorper rams were randomly divided into four homogeneous experimental groups (n = 5 males each) regarding live weight (LW), body condition score (BCS), scrotal circumference (SC) and odor intensity (OI). Then, groups were treated with: i) GG (7 mg kg-1 LW of glutamate, every 4d × 30d, im.), ii) GGT (7 mg kg-1 LW of glutamate every 4d × 30d im + 25 mg of testosterone propionate, every 3d × 15d, im.), iii) GT (25 mg of testosterone propionate every 3d × 15d, im, and iv) GC (1 mL of saline, every 4d × 30d, im.). Thereafter, Dorper rams, (n = 4 per group) were selected and exposed to Dorper anovulatory-nulliparous ewes divided in four groups (n = 14 ewes each), and all the appetitive (ASB) and consummatory (CSB) sexual behaviors and indicators of sexual rest (ISR) were registered during the first 48 h of this male-to-females contact. Thereafter, males continued the male-to-female contact for another 8 d, in order to quantify the ewe's sexual and reproductive response through the male effect. During the sexual behavior tests, the GGT rams showed the highest ASB + CSB frequencies (P < 0.05) followed by the GG-rams with the lowest frequencies showed by the GC and GT groups. While the highest ISR behaviors were shown by the GG and GGT groups (P < 0.05) followed by the GC and GT-rams, no differences occurred regarding LW, BCS, and SC along the experimental breeding, with the largest (P < 0.05) OI shown by the GGT-rams and the lowest value observed in the control rams. Regarding the reproductive response of the nulliparous-anovulatory ewes exposed to treated rams, the glutamate + testosterone treated males induced not only an increased (P < 0.05) ovulatory activity and faster (P < 0.05) estrus response but an augmented (P < 0.05) pregnancy rate of the previously anovulatory ewes. To conclude, whereas the GG and GGT treatments generated encouraging sexual and reproductive outcomes, our results are also thought-provoking from a comparative sexual behavior perspective while may embrace potential applications to other animal industries.

PACAP-(6-38) or kynurenate microinjections in the RVLM prevent the development of sympathetic long-term facilitation after acute intermittent hypoxia.

Intermittent hypoxia causes a persistent increase in sympathetic activity that progresses to hypertension in chronic conditions such as obstructive sleep apnea. Pituitary adenylate cyclase-activating polypeptide (PACAP) is an excitatory neurotransmitter that causes long-lasting sympathetic excitation. We aimed to determine if intermittent activation of the rostral ventrolateral medulla (RVLM) causes PACAP-mediated elevation of sympathetic nerve activity, termed sympathetic long-term facilitation (sLTF). The role of PACAP in mediating sLTF in response to intermittent activation of the RVLM was investigated in urethane-anaesthetized and artificially ventilated rats ( n = 65, Sprague-Dawley). Bilateral RVLM microinjections of the PACAP type 1 receptor/vasoactive intestinal polypeptide receptor type 2 receptor antagonist PACAP-(6-38) [ n = 6, change (Δ): -16.4 ± 6.5%) or an ionotropic glutamate antagonist, kynurenate ( n = 6, Δ:-7.2 ± 2.3%), blocked the development of acute intermittent hypoxia-induced sLTF ( n = 6, Δ: 49.2 ± 14.2%). Intermittent RVLM microinjections of glutamate caused sLTF ( n = 5, Δ: 56.9 ± 14.7%) that was abolished by PACAP-(6-38) pretreatment ( n = 5, Δ:-1.2 ± 4.7%). Conversely, intermittent microinjections of PACAP in the RVLM did not elicit sLTF. Intermittent bilateral disinhibition of the RVLM by microinjection of γ-aminobutyric acid in the caudal ventrolateral medulla did not elicit sLTF. Direct activation of RVLM neurons is crucial for the development of sLTF. PACAP and glutamate act synergistically in the RVLM, with both being necessary for the sLTF response. We found that activation of glutamate but not PACAP receptors is necessary and sufficient to generate sLTF, even in the absence of intermittent hypoxia. Our results demonstrate that PACAP within the RVLM may contribute to the development of obstructive sleep apnea -induced hypertension. NEW & NOTEWORTHY Pharmacological blockade of either pituitary adenylate cyclase-activating polypeptide (PACAP) or ionotropic glutamate receptors in the rostral ventrolateral medulla prevents development of sympathetic long-term facilitation. PACAP receptor inhibition prevents the occurrence of hypoxia-induced peripheral chemoreflex sensitization. Thus, PACAP receptors may be a potential therapeutic target serving to reduce heightened sympathetic tone and hypersensitized cardiovascular reflexes.

Effects of three major amino acids found in Japanese broth on glucose metabolism and gastric emptying.

OBJECTIVES: To our knowledge, the effect of the broth of dried kelp and dried bonito, dashi, on glucose metabolism and digestion has rarely been studied. Based on the component analysis of three actual broths served in traditional restaurants, a chemically synthesized broth with three free amino acids (histidine, glutamate, aspartate) and salt was prepared to investigate their effect on glucose metabolism, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide 1 (GLP-1) secretion, and digestion. METHODS: In study 1, seven healthy individuals were enrolled in a four-period crossover study. Participants drank or ate hot water, synthesized broth, hot water with rice, and synthesized broth with rice. Plasma glucose, serum insulin, plasma glucagon, plasma GIP, and plasma GLP-1 were measured at baseline and after ingestion. In study 2, 6 of the 7 individuals ingested rice steamed with 13C-labeled sodium acetate with hot water or synthesized broth to estimate gastric emptying by the 13C-labeled acetate breath test in a two-period crossover trial. RESULTS: Ingesting water or synthesized broth alone elicited no change in plasma glucose or serum insulin levels. Ingesting synthesized broth with rice resulted in a rapid rise in plasma glucose and GLP-1 (P = 0.01 and 0.02, respectively) in an early postprandial phase compared with that by ingesting water with rice, but the area under the curve of those showed no significant differences. Ingesting synthesized broth with rice resulted in a significantly higher gastric emptying coefficient than that after rice with water (P = 0.03). CONCLUSIONS: Three amino acids and sodium chloride corresponding to those found in actual broth promoted gastric emptying and led to a rapid response of plasma glucose. Our findings suggest that ingestion of the broth of dried kelp and dried bonito may improve gastric motility.

Dietary glutamine, glutamate and mortality: two large prospective studies in US men and women.

Background: Emerging studies have related circulating glutamine metabolites to various chronic diseases such as cardiovascular disease and cancer; diet is the major source of nutrients involved in glutamine metabolism. However, it remains unknown whether dietary intakes of glutamine, glutamate,and their ratio are related to total and cause-specific mortality. Methods: We followed 74 082 women from the Nurses' Health Study (1984-2012) and 42 303 men from the Health Professionals Follow-up Study (1986-2012), who were free of cardiovascular disease and cancer at baseline. Diet was updated every 2 to 4 years by using validated food frequency questionnaires. The content of glutamine and glutamate in foods was calculated based on protein fractions generated from gene sequencing methods and adjusted for total energy intake. Results: We documented 30 424 deaths during 2 878 344 person-years of follow-up. After adjustment for potential confounders including lifestyle and dietary factors, higher intakes of glutamine and glutamine-to-glutamate ratio were associated with significantly lower risk of total and cause-specific mortality. Compared with people in the lowest quintile of dietary glutamine-to-glutamate ratio, the pooled hazard ratio (HR) in the highest quintile was 0.87 [95% confidence interval (CI): 0.84, 0.91; P for trend < 0.001) for total mortality, 0.81 (95% CI: 0.75, 0.88; P for trend < 0.001) for cardiovascular mortality, and 0.93 (95% CI: 0.87, 0.99; P for trend = 0.01) for cancer mortality. Conclusions: We found dietary glutamine and glutamine-to-glutamate ratio were inversely related to risk of mortality, particularly cardiovascular mortality, independent of other dietary and lifestyle factors, in US men and women.

Posterior hypothalamus glutamate infusion decreases pentylenetetrazol-induced seizures of male rats through hippocampal histamine increase.

OBJECTIVES: Seizures are epileptic manifestations that are intrinsically modulated through different neurotransmitters and receptor systems. Although glutamate increases excitation and hence seizures, it activates other systems which could potentially terminate seizures. Histamine originates from neurons of the posterior hypothalamus (PH) and can mediate anticonvulsant properties, but the effect of local PH glutamate on hippocampal histamine content is unknown. Therefore, in this study, the effect of PH glutamate and the involvement of hippocampal histamine in pentylenetetrazol (PTZ) induced seizure activity was studied. MATERIALS AND METHODS: OX2R antagonist (TCS OX2 29, 40nmol/1µl, intra-PH), AMPA/Kainate receptor antagonist (CNQX, 3mM, intra-PH) and glutamate (1mM) were injected bilaterally into PH using stereotaxic surgery. The intravenous PTZ infusion model was used to generate behavioral convulsions and the amount of hippocampal histamine content was then measured using a biochemical method. RESULTS: Administration of glutamate into PH decreased both seizure stage and the duration of tonic-clonic convulsion (TCC) with increasing TCC latency and hippocampal histamine content. Blocking OX2Rs alone or coinhibition of OX2Rs and AMPA/kainate receptors reversed these effects by increasing both seizure stage and TCC duration, and by decreasing both latency and consequent histamine content. CONCLUSIONS: Our findings suggest that glutamate administration into PH may control seizures (stages and duration) through increasing the hippocampal histamine content.

Protective effects of dietary glycine and glutamic acid toward the toxic effects of oxidized mustard oil in rabbits.

The protective role of glycine and glutamic acid against the toxic effects of oxidized oil was studied for the first time. Mustard seed oil was thermally oxidized and characterized for quality characteristics and polyphenolic composition using reversed phase HPLC-DAD. Significant changes in the quality characteristics occurred with thermal oxidation. Fourteen polyphenolic compounds were identified and quantified in oils. Quercetin-3-glucoside, quercetin-3-feruloylsophoroside, catechin, quercetin-3-rutinoside, quercetin-3,7-diglucoside, sinapic acid and vanillic acid hexoside were the major compounds in the fresh and oxidized oil. Oxidized, un-oxidized mustard oils, glycine and glutamic acid were given to rabbits alone or in combination. The biochemical responses were studied in terms of haematological and biochemical parameters and histopathology. It has been observed that biochemical and haematological parameters were adversely affected by the oxidized oil, while supplementation of both amino acids was beneficial in normalizing these parameters. Both amino acids alone have no significant effects, however, oxidized oil affected the liver by enhancing fat accumulation, causing hepatitis, reactive Kupffer cells and necrosis. The co-administration of oxidized oils with glycine or glutamic acid revealed significant recovery of the liver structure and function. In conclusion, glycine or glutamic acid is beneficial and protective against food toxicity and can be considered as an ameliorative food supplement.

Low dose of L-glutamic acid attenuated the neurological dysfunctions and excitotoxicity in bilateral common carotid artery occluded mice.

Glutamate, an excitatory neurotransmitter in the brain, produces excitotoxicity through its agonistic action on postsynaptic N-methyl-D-aspartate receptor, resulting in neurodegeneration. We hypothesized that the administration of low doses of glutamate in cerebral ischemia could attenuate the excitotoxicity in neurons through its autoreceptor regulatory mechanism, and thereby control neurodegeneration. To test the hypothesis, the effect of L-glutamic acid (L-GA) 400 µmol/l/kg was evaluated in a bilateral common carotid artery occlusion-induced global ischemic mouse model. Memantine was used as a positive control. Global ischemia in mice was induced by occlusion of both the common carotid artery (bilateral common carotid artery occlusion) for 20 min, followed by reperfusion injury. L-GA was infused slowly through the tail vein 30 min before the surgery and every 24 h thereafter until the end of the experiment. The time-dependent change in cerebral blood flow was monitored using a laser Doppler image analyzer. The neurotransmitters glutamate and γ-aminobutyric acid (GABA) and the neurobiochemicals ATP, glutathione, and nitric oxide were measured in the different regions of brain at 0, 24, 48, and 72 h after reperfusion injury. L-GA increased locomotor activity, muscle coordination, and cerebral blood flow in ischemic mice at 72 h after ischemic insult. L-GA reduced glutamate levels in the cortex, striatum, and hippocampus at 72 h, whereas GABA levels were elevated in all three brain regions studied. Further, L-GA elevated glutathione levels and attenuated nitric oxide levels, but failed to restore ATP levels 72 h after ischemia-reperfusion. We conclude that the gradual reduction of glutamate along with elevation of GABA in different brain regions could have contributed toward the neuroprotective effect of L-GA. Hence, a slow infusion of a low dose of L-GA could be beneficial in controlling excitotoxicity-induced neurodegeneration following ischemia.

Post hoc analysis of the glutamics-trial: intravenous glutamate infusion and use of inotropic drugs after cabg.

BACKGROUND: Intravenous glutamate reduced the risk of developing severe circulatory failure after isolated coronary artery bypass graft surgery (CABG) for acute coronary syndrome (ACS) in a double-blind randomised clinical trial (GLUTAMICS-ClinicalTrials.gov Identifier: NCT00489827 ). Here our aim was to study if glutamate was associated with reduced the use of inotropes. METHODS: Post-hoc analysis of 824 patients undergoing isolated CABG for ACS in the GLUTAMICS-trial. ICU-records were retrospectively scrutinised including hourly registration of inotropic drug infusion, dosage and total duration during the operation and postoperatively. RESULTS: ICU-records were found for 171 out of 177 patients who received inotropes perioperatively. Only one fourth of the patients treated with inotropes fulfilled study criteria for postoperative heart failure at weaning from cardiopulmonary bypass (CPB) or later in the ICU. Inotropes were mainly given preemptively to facilitate weaning from CPB or to treat postoperative circulatory instability (bleeding, hypovolaemia). Except for a significantly lower use of epinephrine there were only trends towards lower need of other inotropes overall in the glutamate group. In patients treated with inotropes (glutamate n = 17; placebo n = 13) who fulfilled study criteria for left ventricular failure at weaning from CPB the average duration of inotropic treatment (34 ± 20 v 80 ± 77 h; p = 0.014) and the number of inotropes used (1.35 ± 0.6 v 1.85 ± 0.7; p = 0.047) were lower in the glutamate group. CONCLUSIONS: Intravenous glutamate was associated with a minor influence on inotrope use overall in patients undergoing CABG for ACS whereas a considerable and significant reduction was observed in patients with heart failure at weaning from CPB.

Novel pH-Sensitive Cyclic Peptides.

A series of cyclic peptides containing a number of tryptophan (W) and glutamic acid (E) residues were synthesized and evaluated as pH-sensitive agents for targeting of acidic tissue and pH-dependent cytoplasmic delivery of molecules. Biophysical studies revealed the molecular mechanism of peptides action and localization within the lipid bilayer of the membrane at high and low pHs. The symmetric, c[(WE)4WC], and asymmetric, c[E4W5C], cyclic peptides translocated amanitin, a polar cargo molecule of similar size, across the lipid bilayer and induced cell death in a pH- and concentration-dependent manner. Fluorescently-labelled peptides were evaluated for targeting of acidic 4T1 mammary tumors in mice. The highest tumor to muscle ratio (5.6) was established for asymmetric cyclic peptide, c[E4W5C], at 24 hours after intravenous administration. pH-insensitive cyclic peptide c[R4W5C], where glutamic acid residues (E) were replaced by positively charged arginine residues (R), did not exhibit tumor targeting. We have introduced a novel class of cyclic peptides, which can be utilized as a new pH-sensitive tool in investigation or targeting of acidic tissue.

Synthesis and evaluation of a glutamic acid-modified hPAMAM complex as a promising versatile gene carrier.

Hyperbranched poly(amidoamine) (HPAMAM), structurally analogous to polyamidoamine dendrimer (PAMAM) dendrimers, has been suggested to be an effective carrier for gene delivery. In the present study, glutamic acid-modified hPAMAM was developed as a novel non-viral gene carrier for the first time. The hPAMAM was synthesized by using a modified one-pot method. DNA was found to be bound to hPAMAM at different weight ratios (WhPAMAM/WDNA). The resulting HPAMAM-Glu20 was able to efficiently protect the encapsulated-DNA against degradation for over 2 h. In addition to low cytotoxicity, the transfection efficiency of hPAMAM-Glu20 represented much higher (p < 0.05) than that of Lipofectamine 2000 in both MCF7 and MDA-MB231 cells. Cellular uptake of the hPAMAM-Glu20 in MDA-MB231 cells, 173.56 ± 1.37%, was significantly higher than that of MCF7 cells, 65.00 ± 1.73% (p < 0.05). The results indicated that hPAMAM-Glu20-mediated gene delivery to breast cancer cells is a feasible and effective strategy that may provide a new therapeutic avenue as a non-viral gene delivery carrier. In addition, it was found that hPAMAM-glutamic amino acid (Glu)-based gene delivery is an economical, effective and biocompatible method.