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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 ...
Phillis J W - - 1999
The effects of the phospholipase activator melittin on amino acid and free fatty acid release from the rat cerebral cortex were monitored and compared with those of a secretory PLA(2), using a cortical cup technique with topical application of these agents in artificial cerebrospinal fluid. Melittin (10 microg/ml; 3.5 microM) ...
Kulagina N V - - 1999
This paper describes electrochemical microsensors for the in vivo measurement of glutamate and ascorbate in the extracellular space of brain tissue. To prepare glutamate microsensors, carbon fiber microelectrodes (10 microns in diameter and 300-400 microns long) were modified with a cross-linked redox polymer film containing enzymes. The microsensors were coated ...
Pasantes-Morales H - - 1999
Amino acids play a role as osmolytes during the regulatory volume decrease subsequent to hyposmotic swelling, but less is known about its role when swelling occurs in isosmotic conditions. In this work we examined the efflux of labelled GABA, taurine and glutamate (traced as D-aspartate) from the chick retina, after ...
Verity C K - - 1999
Schistosomes utilise haemoglobin from ingested host erythrocytes as their main source of amino acids. Using reverse-transcriptase PCR, we detected transcripts encoding cathepsin D in eggs, miracidia, and adult male, female and mixed-sex Schistosoma japonicum. Using the synthetic fluorogenic peptide, o-aminobenzoyl-isoleucyl-glutamyl-phenylalanyl-p-nitro-phenylalanyl-a rgi nyl-leucine-NH2, and human haemoglobin as substrates, we detected cathepsin ...
Napper G A - - 1999
Glutamate and gamma-aminobutyric acid (GABA) are the dominant amino acids in the retina and brain. The manufacturing and degradation pathways of both of these amino acids are intricately linked with the tricarboxylic acid cycle leading to rapid redistribution of these amino acids after metabolic insult. Postmortem ischemia in mammalian retina ...
Jones P - - 1999
The transfer of label from 15N-alanine and 15N-glutamate into amino acids in incubated brain slices has been followed using gas chromatography/mass spectrometry (GC/MS). 15N from alanine appeared in both amino and amide groups of glutamine more rapidly than into aspartate, glutamate and GABA, which were all labeled at similar rates. ...
Sherwin A L - - 1999
Studies of neuroactive amino acids and their regulatory enzymes in surgically excised focally epileptic human brain are reviewed. Concentrations of glutamate, aspartate and glycine are significantly increased in epileptogenic cerebral cortex. The activities of the enzymes, glutamate dehydrogenase and aspartate aminotransferase, involved in glutamate and aspartate metabolism are also increased. ...
Viano J - - 1999
A survey of compositional characteristics of the aerial part of sheep's burnet (Sanguisorba minor ssp. muricata) growing in Mediterranean French pastures has been undertaken. Investigations with scanning electron microscopy gave the morphological structure of this plant, in particular for akene ornamentation. Taxonomic characters confirmed the identification of the muricata subspecies. ...
Kalloniatis M - - 1999
The dominant neurochemicals involved in encoding sensory information are the amino acid neurotransmitters, glutamate, gamma-aminobutyrate (GABA) and glycine, which mediate fast point-to-point synaptic transmission in the retina and other parts of the central nervous system. The relative abundance of these neurochemicals and the existence of neuronal and glial uptake mechanisms ...
Yang C S - - 1999
Glutamate is an important excitatory amino acid in central nervous system. We developed a method for in vivo, continuous and automatic monitoring of brain extracellular glutamate, as well as other amino acids in anesthetized rat. This method involves the use of microdialysis perfusion technique and a high-performance liquid chromatography system ...
Estevez A Y - - 1999
In an evaluation of the contribution of swelling-induced amino acid release, through the regulatory volume decrease (RVD) process, to cerebral ischemic injury, studies of the role of phospholipases and protein kinases in the response to hyposmotic stress were undertaken using an in vivo rat cortical cup model. Hyposmotic stress induced ...
Waagepetersen H S - - 1999
GABA, which is present in the brain in large amounts, is distributed among distinctly different cellular pools, possibly reflecting its multiple functions as metabolite, neurotransmitter, and neurotrophin. Its metabolic enzymes also exhibit heterogeneity, because glutamate decarboxylase exists in two isoforms with different subcellular distribution and regulatory properties. Moreover, recent evidence ...
Delaunay S - - 1999
To give clues about the respective importance of phosphoenol-pyruvate carboxylase (PEPc) and pyruvate carboxylase (Pc) in Corynebacterium glutamicum metabolism during a temperature triggered glutamic acid fermentation, PEPc activity was genetically amplified and Pc activity was suppressed by biotin limitation in the culture medium. In absence of Pc activity, glutamate production ...
Matsumoto M - - 1999
The occurrence of free D-amino acids and aspartate racemases in several hyperthermophilic archaea was investigated. Aspartic acid in all the hyperthermophilic archaea was highly racemized. The ratio of D-aspartic acid to total aspartic acid was in the range of 43.0 to 49.1%. The crude extracts of the hyperthermophiles exhibited aspartate ...
Fairbanks L D - - 1999
Leflunomide is an immunomodulatory drug which acts by inhibiting dihydroorotic acid dehydrogenase, the fourth enzyme of pyrimidine biosynthesis. We modified our high-performance liquid chromatography method to demonstrate that the principal metabolite in mitogen-stimulated human T-lymphocytes incubated with leflunomide was not dihydroorotic acid, but carbamoyl aspartate. Identification involved preparation of [14C]carbamoyl ...
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