Search Results
Results 551 - 600 of 1834
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Ross I A - - 2000
Pronounced glutamic acid uptake was observed after only 15 min with glutamate concentrations of 60 nmol/mg protein when astrocytes were incubated with 1 mM glutamic acid. The uptake increased with time to a steady-state glutamate level of above 160 nmol/mg protein by 45 min. The uptake was energy dependent. Reduced ...
Kansal V K - - 2000
L-glutamate was transported into mammary tissue via Na(+)-dependent system XAG- that strongly interacted with both D- and L-isomers of aspartate but only with L-isomer of glutamate. Replacement of Cl- by gluconate from the extracellular medium did not affect the uptake of L-glutamate. Although neutral amino acids weakly inhibited the uptake ...
Hill E - - 2000
Glutamate is an important amino acid in the neocortex for metabolic and neurotransmitter functions. The objective of this study was to detect variations in cellular glutamate content using quantitative immunocytochemistry. We show that glutamate is present in almost all cortical cells and coexists with other amino acids such as aspartate, ...
Agostoni C - - 2000
BACKGROUND: Previous short observational studies on the free amino acid (FAA) content of human milk have shown that glutamine and glutamic acid increase in the first 4 to 6 weeks of life. METHODS: Changes in human milk content of free amino acids (FAAs) was determined at colostrum, 1 month, and ...
Harada C - - 2000
Excessive glutamate receptor activation is thought to be involved in the retinal ganglion cell (RGC) death after ischemic injury. In this study, we examined the effect of 2-PMPA (2-(phosphonomethyl)pentanedioic acid) on RGC survival in an ischemia-reperfusion model using C57BL/6 mouse eyes. 2-PMPA is a NAALADase (N-acetylated-alpha-linked-acidic dipeptidase) inhibitor, an enzyme ...
Johns L - - 2000
The aim of this study was to investigate the effects of preconditioning on amino acid neurotransmitter release, induced by hypoxia/hypoglycaemia, from rat brain cortical slices. Tissue, perfused with artificial cerebrospinal fluid (aCSF) at 37 degrees C with zero glucose and gassed with 95% nitrogen and 5% carbon dioxide, showed a ...
Connolly P J - - 2000
N,N-Dicinnamyl, N-benzyl-N-cinnamyl, and N,N-dibenzyl amino acids were prepared and evaluated in an EPO binding assay. Several derivatives of aspartic acid, glutamic acid, and lysine exhibited moderate (10-50 microM) affinity for EBP; 'dimerization' of the most potent analogues by coupling with linear diamines led to EPO competitors having 1-2 microM binding ...
Savic I - - 2000
OBJECTIVE: To investigate whether cerebral levels of N-acetyl aspartate (NAA), and glutamine + glutamate (Glx), are interictally altered in the epileptogenic regions of patients with partial seizures. MATERIAL AND METHODS: NAA, Glx, creatine (Cr), choline (Cho) and myo-inositol (mI) was measured in 28 patients with partial epilepsy and 10 healthy ...
Berg H - - 2000
Biosynthesis of the cyanobacterial nitrogen reserve cyanophycin (multi-L-arginyl-poly-L-aspartic acid) is catalysed by cyanophycin synthetase, an enzyme that consists of a single kind of polypeptide. Efficient synthesis of the polymer requires ATP, the constituent amino acids aspartic acid and arginine, and a primer like cyanophycin. Using synthetic peptide primers, the course ...
Deore B - - 2000
Overoxidized polypyrrole films templated with L-glutamate have been utilized for enantioselective detection of L- and D-glutamic acid. Various important fabrication factors controlling the performance of the overoxidized polypyrrole films have been investigated using fluorescence spectrometry in conjugation with the electrochemical quartz crystal microbalance technique. The measured fluorescence intensity was related ...
Gramsbergen J B - - 2000
Previously, we have shown that 3-nitropropionic acid (NPA) neurotoxicity in organotypic corticostriatal slice cultures is dependent on glucose and glutamate. Here we studied the neuroprotective potential of agents improving mitochondrial function, including creatine, malate, oxaloacetate, Pyruvate and L-lactate in NPA-treated slice cultures. pyruvate provided the best protection against the loss ...
Mutlib A E - - 2000
With the advent of liquid chromatography/mass spectrometry and liquid chromatography/NMR, it has become easier to characterize metabolites that were once difficult to isolate and identify. These techniques have enabled us to uncover the existence of an alternate pathway for the disposition of glutathione adducts of several structurally diverse compounds. Studies ...
Ueda Y Y Department of Psychiatry, Miyazaki Medical College, Kiyotake, Japan. - - 2000
Epileptiform discharges and behavioral seizures may be the consequences of the presence of either excessive excitation associated with the neurotransmitter glutamate or from inadequate inhibitory effects associated with gamma-aminobutyric acid (GABA). Synaptic effects of these neurotransmitters are terminated by the action of transporter proteins that remove these amino acids from ...
Sistiaga A - - 2000
We have addressed the role of arachidonic acid in the facilitation of glutamate release by group I metabotropic glutamate (mGlu) receptors. The activation of these receptors with the specific agonist 3,5-dihydroxyphenylglycine (DHPG) failed to enhance the cumulative Ca(2+)-dependent release of glutamate evoked by a 5 min depolarization with 4-aminopyridine, in ...
Guyot L L - - 2000
Insulin has been reported to be neuroprotective during cerebral ischemia/reperfusion. However, it may also increase the sensitivity of cultured cortical neurons to glutamate toxicity. The experiments described here utilized a rat four-vessel occlusion model with cerebral cortical windows to determine the effects of intravenous insulin, alone (I) or combined with ...
Tree T I - - 2000
AIMS/HYPOTHESIS: Glutamic acid decarboxylase 65 is a major autoantigen in Type I (insulin-dependent) diabetes mellitus, autoimmune polyendocrine syndrome and stiff-man syndrome. These disorders are characterised by the presence of multiple autoantibodies to the autoantigen which can be distinguished in a variety of different ways. We have investigated the role of ...
Tam Y Y - - 2000
Amide-linked indole-3-acetic acid (IAA) conjugates constitute approximately 90% of the IAA pool in the dicot Arabidopsis, whereas ester-linked conjugates and free IAA account for approximately 10% and 1%, respectively when whole seedlings are measured. We show here that IAA-aspartate Asp, IAA-glutamate (Glu), and IAA-glucose (Glc) are present at low levels ...
Zheng L - - 2000
High K+ was used to depolarize glia and neurons in order to study the effects on amino acid release from and concentrations within the dorsal cochlear nucleus (DCN) of brain slices. The release of glutamate, gamma-aminobutyrate (GABA) and glycine increased significantly during exposure to 50 mM K+, while glutamine and ...
Jabaudon D - - 2000
The extracellular glutamate concentration ([glu](o)) rises during cerebral ischemia, reaching levels capable of inducing delayed neuronal death. The mechanisms underlying this glutamate accumulation remain controversial. We used N-methyl-D-aspartate receptors on CA3 pyramidal neurons as a real-time, on-site, glutamate sensor to identify the source of glutamate release in an in vitro ...
Lawand N B - - 2000
This study examined the release of several amino acids after induction of knee joint inflammation in rats using kaolin and carrageenan. During the initial 10-min collection after knee joint injection with the irritants, the concentration of glutamate and the nitric oxide metabolites, arginine and citrulline, doubled. This increase persisted for ...
Timmerman M - - 2000
Intravenous infusion of dexamethasone (Dex) in the fetal lamb causes a two- to threefold increase in plasma glutamine and other glucogenic amino acids and a decrease of plasma glutamate to approximately one-third of normal. To explore the underlying mechanisms, hepatic amino acid uptake and conversion of L-[1-(13)C]glutamine to L-[1-(13)C]glutamate and ...
Boone A N - - 2000
Acetyl-CoA carboxylase (ACC) catalyzes the formation of malonyl-CoA, an essential substrate for fatty acid biosynthesis and a potent inhibitor of fatty acid oxidation. Here, we provide evidence that glutamate may be a physiologically relevant activator of ACC. Glutamate induced the activation of both major isoforms of ACC, prepared from rat ...
Garattini S - - 2000
This review examines progress in understanding the physiologic functions of glutamic acid in the body since the first symposium on glutamic acid physiology and biochemistry was held at the Mario Negri Institute in Milan in 1978. The topics reviewed, although not exhaustive, include the metabolism of glutamic acid, umami taste, ...
Yang D - - 2000
In isotopic experiments, the labeling pattern of glutamate opens a window on hepatic metabolism, particularly the citric acid cycle, gluconeogenesis and fatty acid oxidation. This is because glutamate is in isotopic equilibrium with alpha-ketoglutarate, whose labeling pattern is influenced by the following: 1) the contributions of glucose and fatty acids ...
Yudkoff M - - 2000
The relationship between acidosis and the metabolism of glutamine and glutamate was studied in cultured astrocytes. Acidification of the incubation medium was associated with an increased formation of aspartate from glutamate and glutamine. The rise of the intracellular content of aspartate was accompanied by a significant decline in the extracellular ...
Kim T W - - 2000
OBJECTIVE: To explore the possibility that an elevation of glutamate levels in the vitreous might be associated with the microvascular compromise of the optic nerve. MATERIALS AND METHODS: Endothelin-1, 0.1 microg/d (5 rabbits), or balanced salt solution (4 rabbits) was delivered to the perineural region of the anterior optic nerve ...
Young V R - - 2000
In this introductory paper to the symposium, we consider why L-glutamate (GLU) is such an abundant biomolecule. We begin with a brief discussion of the prebiotic dawn of events and some evolutionary features of GLU in the biological and metabolic world. The properties of GLU are then examined with reference ...
Daikhin Y - - 2000
Intrasynaptic [glutamate] must be kept low in order to maximize the signal-to-noise ratio after the release of transmitter glutamate. This is accomplished by rapid uptake of glutamate into astrocytes, which convert glutamate into glutamine. The latter then is released to neurons, which, via mitochondrial glutaminase, form the glutamate that is ...
Brosnan J T - - 2000
The liver is the major site of gluconeogenesis, the major organ of amino acid catabolism and the only organ with a complete urea cycle. These metabolic capabilities are related, and these relationships are best exemplified by an examination of the disposal of the daily protein load. Adults, ingesting a typical ...
Kalic M - - 2000
The (1)H NMR spectrum of the perchloric acid extract of carp seminal plasma was heavily congested. It is demonstrated that proton-detected C,H chemical shift correlation spectroscopy (HSQC, HSQC-TOCSY) allows an unequivocal identification of proline, glutamate, taurine, and methionine sulfoxide, although several key proton signals were strongly overlapped.
Kumar S - - 2000
Accumulation of GABA and a concurrent block in the Krebs cycle suggest a functional GABA bypass in the acidogenic Aspergillus niger. Apart from the demonstration of enzyme machinery required, a direct measurement of flux through this glutamate decarboxylation loop was attempted. The distribution of carbon from glucose and glutamate was ...
McNearney T - - 2000
OBJECTIVE: Previous studies in an experimental synovitis model in rats determined that administration of glutamate and aspartate into the joint produces hyperalgesic responses, while their receptor antagonists provide protection against the development of a hyperalgesic state. We examined concentrations of amino acids in synovial fluid (SF) to determine if increases ...
Porciúncula L O - - 2000
Synaptosomes and plasma membrane preparations from brain of 30-day-old rats were incubated with glutaric acid at final concentrations ranging from 10 nM to 1 mM for the determination of glutamate uptake and binding, respectively. [3H]Glutamate uptake into synaptosomes was inhibited by approximately 50% by 1 mM glutaric acid, corresponding to ...
Koyama Y - - 2000
We characterized swelling of rat cultured astrocytes induced by L-glutamate and its analogues. Among L-glutamate receptor agonists, L-glutamate, L-aspartate, L-cysteic acid, DL-homocysteic acid, quisqualate and (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD) increased astrocytic intracellular volume (3H-OMG space), while kainate, and N-methyl-D-aspartate did not. Threo-beta-hydroxyaspartate (TBHA), D-aspartate and L-trans-pyrrolidine-2,4-dicarboxylic acid, high-affinity substrates for Na+-dependent ...
Miranda-Contreras L - - 2000
The developmental changes in the levels of amino acid neurotransmitters were analyzed by high pressure liquid chromatography during mouse olfactory bulb neurogenesis, from embryonic day (E)13 until the young adult age, between postnatal days (P)30 and P40. During the embryonic period, high levels of glutamate, aspartate and GABA were observed, ...
Al-Sarraf H - - 2000
The acidic amino acids aspartate and glutamate are excitatory neurotransmitters in the CNS. The clearance of this group of amino acids from CSF of adult and neonatal (7-day-old) rats was investigated. Ventriculo-cisternal perfusions with 14C-amino acids and 3H-dextran were carried out for up to 90 min. Uptake of the amino ...
Miele M - - 2000
1. The effects of systemic, intrastriatal or intranigral administration of d-amphetamine on glutamate, aspartate, ascorbic acid (AA), uric acid, dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) concentrations in dialysates from the striatum of freely-moving rats were evaluated using microdialysis. 2. d-Amphetamine (2 mg kg-1) given ...
Dauban P - - 2000
The first synthesis of one of the 4 possible stereoisomers of 3,4-dihydroxy-L-glutamic acid ((3S,4S)-DHGA 3), a natural product of unknown configuration, is described. The synthesis is based on the Lewis acid catalyzed reaction of benzyl alcohol with a D-ribose-derived 2,3-aziridino-gamma-lactone 4-benzyl carboxylate (6). Preliminary pharmacological studies showed that (3S,4S)-3 is ...
Matsuda K - - 2000
The time course of the changes in perilymphatic glutamate was determined during the application of kanamycin and ethacrynic acid, which are known to damage the hair cells in the inner ear. For the continuous recording of glutamate, the microdialysis technique combined with an enzyme-linked fluorometric assay was used. In guinea ...
Raiteri M - - 2000
Small molecules present during brain tissue homogenization are known to be entrapped within subsequently isolated synaptosomes. We have revisited this technique in view of its systematic utilization to incorporate into nerve endings impermeant probes of large size. Rat neocortical synaptosomes were prepared in the absence or in the presence of ...
Reggiani R - - 2000
Accumulation of amino acids was studied in rice roots of 3-day-old seedlings subjected for 48h to anaerobic conditions. Alanine and Gaba were the main amino acids accumulated under anoxia. Their synthesis was strongly inhibited by MSX and AZA, inhibitors of glutamine synthetase and glutamate synthase. These activities increased after 8h ...
Maeda H - - 2000
An efficient procedure for the production of l-[4-13C]aspartic acid (4-13C-Asp) was investigated. In this procedure, phosphoenolpyruvate carboxylase originating from the methanol-assimilating microbe, Methylobacterium extorquens JCM 2805, was used for the production of labeled oxaloacetic acid from phosphoenolpyruvate (PEP) and NaH13CO3; the oxaloacetic acid was then converted to 4-13C-Asp with glutamic-oxaloacetic ...
Broadhurst E R - - 2000
Glutamic acid was found to be growth inhibitory to a murinelymphocyte hybridoma in a concentration-dependent manner from 3to 12 mM glutamate. At 12 mM glutamate there was a 70% decreasein the specific growth rate of the cells. Attempts to alleviateinhibition or adapt cells to growth in glutamate-based mediawere unsuccessful. It ...
Rodehüser L - - 2000
Starting from glutamic acid, different types of surfactants have been synthesised by using original trimodular strategies. Monosubstituted zwitterionic amides of glutamic acid obtained with excellent yields show good surface activity. The grafting of a second hydrophobic side-chain leads to bicatenar cationic surfactants or to disubstituted nonionic cyclic compounds. In order ...
StruzyƄska L - - 2000
Although the clinical manifestations of lead (Pb) neurotoxicity are documented, the subcellular mechanisms of its action are still an open question. The purpose of this study was to assess the function of nerve ending particles after acute lead exposure and to investigate whether it exerts a toxic effect on astroglial ...
Loida P J - - 1999
The metabolite 5-aminolevulinic acid (ALA) is an early committed intermediate in the biosynthetic pathway of heme and chlorophyll formation. In plants, 5-aminolevulinic acid is synthesized via a two-step pathway in which glutamyl-tRNA(Glu) is reduced by glutamyl-tRNA(Glu) reductase (GluTR) to glutamate 1-semialdehyde, followed by transformation to 5-aminolevulinic acid catalyzed by glutamate ...
Belokrylov G A - - 1999
In experiments on mice and the influence in vitro of the dipeptides GluTrp, LysAsp, LysVal, AspGlu, GluAsp on their constituent amino acids and mixtures on the indexes of specific and non-specific resistance was studied. There is no difference between the dipeptides and their constituent amino acids (excepting Lys) neither in ...
Hoop B - - 1999
The ventilatory response to acute hypoxia in mammalian species is biphasic, an initial hyperventilatory response is followed by a reduction in ventilation within 2-3 min below the peak level (roll-off). Brain amino acid neurotransmitters also change during hypoxia. This study explores the role of neurotransmitters in anesthetized adult Sprague Dawley ...
Deane C M - - 1999
Asparagine and aspartate are known to adopt conformations in the left-handed alpha-helical region and other partially allowed regions of the Ramachandran plot more readily than any other non-glycyl amino acids. The reason for this preference has not been established. An examination of the local environments of asparagine and aspartic acid ...
Slusher B S - - 1999
We describe here a new strategy for the treatment of stroke, through the inhibition of NAALADase (N-acetylated-alpha-linked-acidic dipeptidase), an enzyme responsible for the hydrolysis of the neuropeptide NAAG (N-acetyl-aspartyl-glutamate) to N-acetyl-aspartate and glutamate. We demonstrate that the newly described NAALADase inhibitor 2-PMPA (2-(phosphonomethyl)pentanedioic acid) robustly protects against ischemic injury in ...
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