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At least 829 records · Page 46Linked to original sources
PubMed1986

Time course of the reduction of GABA terminals in a model of focal epilepsy: a glutamic acid decarboxylase immunocytochemical study.

Immunocytochemical localization of glutamic acid decarboxylase (GAD), the synthesizing enzyme for the neurotransmitter gamma-aminobutyric acid (GABA), has been used to study the time course of the decrease in putative GABAergic synaptic terminals that occurs in an alumina gel-induced model of focal epilepsy. Monkeys were studied at progressive intervals following unilateral application of alumina gel to sensorimotor cerebral cortex, and were categorized into 3 different experimental groups depending upon their clinical status. These groups respectively exhibited: (1) no abnormal bioelectrical (EEG and ECoG) activity; (2) abnormal bioelectrical activity, but no clinical seizures; and (3) both abnormal bioelectrical activity and clinical seizures. Normal and sham-operated monkeys were also studied. The amounts of GAD-positive terminal-like structures were determined on control and experimental sides of motor cortex (layer V) of all specimens with an image analysis system. This quantitative study revealed that monkeys from the 3 experimental groups showed reductions of GAD-positive terminals on the experimental cortical side, with greater losses occurring at progressively longer times following alumina gel implants. Statistical tests showed that there were no significant cortical side differences for the normal and sham groups, but that cortical side variations were significantly different for each of the 3 experimental groups. Conventional electron microscopy of an early experimental stage revealed degenerating axon terminals in layer V of motor cortex, as well as phagocytosis of degenerating material and astrogliosis. Similar findings were obtained from a chronically epileptic specimen, except that degenerating terminals were observed less often and fibrous astrocytic scarring was more prevalent, especially surrounding the somata of pyramidal neurons. The main conclusion drawn from the results of this investigation is that significant decreases of GAD-positive terminals occur prior to the onset of clinical seizures, and this is consistent with a causal role for a loss of GABAergic innervation in the development of seizure activity in this primate model of focal epilepsy.

Animals↗
PubMed1998

Hippocampal interneurons expressing glutamic acid decarboxylase and calcium-binding proteins decrease with aging in Fischer 344 rats.

Aging leads to alterations in the function and plasticity of hippocampal circuitry in addition to behavioral changes. To identify critical alterations in the substrate for inhibitory circuitry as a function of aging, we evaluated the numbers of hippocampal interneurons that were positive for glutamic acid decarboxylase and those that expressed calcium-binding proteins (parvalbumin, calbindin, and calretinin) in young adult (4-5 months old) and aged (23-25 months old) male Fischer 344 rats. Both the overall interneuron population and specific subpopulations of interneurons demonstrated a commensurate decline in numbers throughout the hippocampus with aging. Interneurons positive for glutamic acid decarboxylase were significantly depleted in the stratum radiatum of CA1, the strata oriens, radiatum and pyramidale of CA3, the dentate molecular layer, and the dentate hilus. Parvalbumin interneurons showed significant reductions in the strata oriens and pyramidale of CA1, the stratum pyramidale of CA3, and the dentate hilus. The reductions in calbindin interneurons were more pronounced than other calcium-binding protein-positive interneurons and were highly significant in the strata oriens and radiatum of both CA1 and CA3 subfields and in the dentate hilus. Calretinin interneurons were decreased significantly in the strata oriens and radiatum of CA3, in the dentate granule cell and molecular layers, and in the dentate hilus. However, the relative ratio of parvalbumin-, calbindin-, and calretinin-positive interneurons compared with glutamic acid decarboxylase-positive interneurons remained constant with aging, suggesting actual loss of interneurons expressing calcium-binding proteins with age. This loss contrasts with the reported preservation of pyramidal neurons with aging in the hippocampus. Functional decreases in inhibitory drive throughout the hippocampus may occur due to this loss, particularly alterations in the processing of feed-forward information through the hippocampus. In addition, such a profound alteration in interneuron number will likely alter inhibitory control of excitability and neuronal synchrony with behavioral states.

Aging↗
PubMed1993

Novel anti-inflammatory undecapeptides that contain anisolyated glutamic acid derivatives.

In various animal models of tissue injury, corticotropin-releasing factor (CRF) and related peptides inhibit swelling, edema and loss of protein from the vascular compartment. To search for smaller peptide segments of CRF that might retain anti-inflammatory activity, the authors tested peptides similar to the carboxy terminals of ovine (o) and human/rat (h/r) CRF. Also, because h/rCRF(35-39), -Arg-Lys-Leu-Met-Glu-, resembles Arg-Lys-Leu-Leu-Glu-, a sequence found in many intermediate filament proteins, analogous peptides were evaluated. Ovine CRF(21-41), -Met-Thr-Lys-Ala-Asp-Gln-Leu-Ala-Gln-Gln-Ala-His-Ser-Asn-Arg-Lys- Leu-Asp-Ile-Ala-NH2, its carboxy terminal carboxyl derivative, oCRF(21-41)-OH, and the fragments, oCRF(26-41) and oCRF(30-41), were inactive when assayed at 5 mg/kg i.v. on edema induced in the pentobarbital-anesthetized rat's hindpaw after immersion in 58 degrees C water for 1 min. Crude peptides, D-Leu-Ala-Thr-D-Tyr-Arg-Lys-Leu-Leu-Glu-Ile-D-Leu-NH2 and D-Ala-His-Ser-D-Asn-Arg-Lys-Leu-Leu-Glu-Ile-D-Leu-NH2, were found to have activity in this bioassay. Characterization of the structures within the crude mixture revealed that substitution of the glutamic acid residue with an anisolyated glutamic acid (2-amino-5-(methoxyphenyl)-5-oxopentanoic acid) derivative, designated as (A*), increased the overall potency. The glutamyl-anisole derivative was a by-product of the temperature-dependent Friedel-Crafts acylation reaction that occurs during hydrogen fluoride cleavage of glutamyl-containing peptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1985

Acute and short term effects of ethanol on the metabolism of glutamic acid and GABA in rat brain.

Although alcoholic intoxication is attributed to its pharmacological effects on the cell membranes in brain, the rapid metabolic utilisation of the same alters the metabolism of brain affecting the metabolism of glutamate and GABA which have varied metabolic roles besides serving a major proportion of synaptic activity. A study on the effects of ethanol, both acute and short-term, on glutamate (glu) and GABA metabolism in various regions of rat brain was carried out. Increased activities of glutamic acid decarboxylase (GAD) and aspartic acid aminotransferase (AST) in all brain regions, but decreased activity of glutamic acid dehydrogenase (GDH) in cerebral cortex (CC) and cerebellum (CB) following ethanol administration in brain was observed. Differential effects of ethanol were also obtained on the contents of glu and aspartate (asp), which were increased in CC, CB, and brain stem (BS) regions, as opposed to GABA content, which, although found to increase in acute toxicity, showed a decrease in all of the above brain regions in short-term toxicity. It is concluded that the above changes in glu, asp and GABA represent the consequences of metabolic utilization of alcohol in the brain, probably more a state of cerebral excitation than depression, and the changes may be a compensatory phenomenon.

Alanine Transaminase↗
PubMed1988

In vitro and in vivo N-acetylation of carcinogenic glutamic acid pyrolysis products in humans.

The carcinogenic glutamic acid pyrolysis products, 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1) and 2-aminodipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2), and their N-acetyl derivatives have been demonstrated to be present in human urine, bile, liver and kidney. In vitro experiments have revealed that Glu-P-1 and Glu-P-2 are N-acetylated to form N-acetyl derivatives by the cytosolic fraction from a human autopsy liver specimen. From these results our data strongly suggest that Glu-P-1 and Glu-P-2 derived from everyday foods are partially N-acetylated in human organs and that they are excreted in bile and urine with their N-acetyl derivatives. Our data also provide the first reliable evidence that humans can metabolize the carcinogenic heterocyclic amines.

Acetylation↗
PubMed2005

Proposals for wastewater treatment by applying flocculating activity of cross-linked poly-gamma-glutamic acid.

Cross-linked poly-gamma-glutamic acid (C-L gamma-PGA) markedly purified polluted water collected from rivers and ponds by flocculation and precipitation. This effect of C-L gamma-PGA occasionally required pretreatment with polyaluminum chloride (PAC). Components of polluted water in rivers or ponds are generally thought to be clay minerals, microorganisms and chemical compounds. In this study, the flocculating activities of C-L gamma-PGA against suspensions of bentonite, diatomaceous earth, Escherichia coli and Mycrocystis aeruginosa, and against solutions of crystal violet and bisphenol A were investigated. The mode of action of C-L gamma-PGA is thought to be based on electrostatic interaction between flocculants, C-L gamma-PGA and PAC, and the surface of polluted water components, which may lead to neutralization of the zeta-potential of those components.

Bacillus subtilis↗
PubMed1999

A novel glutamic acid to aspartic acid mutation near the end of the 2B rod domain in the keratin 1 chain in epidermolytic hyperkeratosis.

We report a mutation in a mild case of epidermolytic hyperkeratosis that results in a glutamic acid to aspartic acid substitution in a novel location, codon 477 or position 106 of the 2B rod domain of the keratin 1 chain. This residue has been conserved in all intermediate filament chains and lies near the beginning of the highly conserved helix termination sequence and just prior to the predicted molecular overlap region. Keratin filaments assembled in vitro from chains bearing this substitution are abnormal, indicating that the glutamic acid residue is critically involved in ionic interactions in intermediate levels of filament structure.

Amino Acid Substitution↗
PubMed2004

Empirical modeling of batch fermentation kinetics for poly(glutamic acid) production and other microbial biopolymers.

An empirical kinetic model is proposed for the batch production of poly(glutamic acid) from Bacillus subtilis IFO 3335. In addition, the proposed model was used to fit the kinetic data of poly(glutamic acid) production from other bacterial strains using different media, as well as kinetic data from different strains for the production of the exocellular biopolymers dextran, hyaluronic acid, xanthan, alginate, and the endocellular biopolymer polyhydroxybutyrate. The empirical model treats the biopolymer as a component of the biomass and fits the experimental biomass data using a sigmoidal relationship that includes the maximum specific growth rate, mu(max), and the substrate saturation parameter, K(S). An empirical parameter, the relative coefficient (r), quantifies, in relative terms, the degree of nongrowth-associated biopolymer formation.

Bacillus subtilis↗
PubMed1989

Ontogeny of cholecystokinin-8 and glutamic acid decarboxylase in cerebral neocortex of macaque monkey.

Concentration of cholecystokinin-8 and the activity of glutamic acid decarboxylase were determined in the various cerebral cortical subdivisions of Japanese monkey (Macaca fuscata fuscata) at three different ages (embryonic 4 months, full-term and adult). The CCK-8 immunoreactive material extracted with 90% methanol from the cerebral cortex of the adult and foetal monkey were shown to be identical with synthetic cholecystokinin-8 by the criterion of co-elution on gel filtration chromatography (Sephadex G-50). The peptide concentration increased dramatically by about 30-80 fold (in terms of protein) and 17-28 fold (in terms of wet weight) between embryonic 4-month-old and full-term monkeys, while the level decreased 1/6-1/16 (protein) and 1/4-1/10 (wet weight) between full-term and adult monkeys. In adults, the highest levels of the peptide was observed in the association cortex, orbital prefrontal cortex and posterior parietal cortex. Glutamic acid decarboxylase activity, on the other hand, gradually increased about 4-10 fold (protein) between embryonic 4-month-old and adult animals and there was little variation in the increase rate among the cerebral subdivisions. In contrast to cholecystokinin-8, no reduction in the enzyme activity occurred between full-term and adult animals. The high level of cholecystokinin-8 in the embryonic period suggests that the peptide may participate in the regulation of the development of primate cerebral cortex.

Aging↗
PubMed1984

Depolarization-induced release of L-glutamic acid from isolated-resealed synaptic membrane vesicles.

L-Glutamic acid actively loaded into resealed brain synaptic membrane vesicles was rapidly released into the incubation medium following the introduction of KCl and CaCl2, or nigericin, or veratridine into the external medium. The KCl-induced release was enhanced by the presence of low (0.1 mM), extravesicular [Ca2+]. Neither the KCl-induced nor the veratridine-stimulated L-glutamate efflux were carrier-mediated processes. Finally, the KCl-stimulated L-glutamate efflux was dependent on the ratio of intra- to extravesicular [K+]. The observations described in this study were indicative of depolarization-induced L-glutamate release from isolated synaptic plasma membrane vesicles.

Animals↗
PubMed1995

Disease sensitivity and specificity of 52 assays for glutamic acid decarboxylase antibodies. The Second International GADAB Workshop.

There is increasing interest in the use of glutamic acid decarboxylase antibodies (GADAbs) for identification of subjects at increased risk of developing insulin-dependent diabetes mellitus (IDDM). However, considerable variation exists between laboratories in the reported frequency of GADAb in various clinical situations, and disease sensitivity and specificity have not yet been compared between assays. An international workshop was held in which 101 coded freeze-dried sera, including 39 from subjects with newly diagnosed IDDM, 32 from healthy control subjects, 4 from nondiabetic subjects with Graves' disease, and 4 from islet cell antibody-positive subjects, were analyzed in 52 assays (radiobinding assay [RBA], 26; enzyme-linked immunosorbent assay [ELISA], 19; and enzymatic immunoprecipitation assay [EIP], 7). The mean sensitivity for RBAs (76.2%) was higher than for ELISAs (36.5%) and EIPs (49.9%) (P < 0.01). The mean specificity was similar for each assay format (RBA, 89.4%; ELISA. 89.4%; and EIP, 92.3%). The lower sensitivities of the ELISA and EIP were predominantly due to the inability of these assays to detect low levels of GADAb in IDDM. To convert results to standard units, standard curves were constructed using duplicate dilutions of the anti-glutamic acid decarboxylase monoclonal antibody MICA 3 and serum from a patient with stiff-man syndrome (SMS). Curves could be derived in 28 assays using the MICA 3 serum and in 29 using the SMS serum. The mean coefficients of variation between assays for disease and control samples were 45% when results were converted to MICA units, 77% for SMS units, and 76% for SD scores.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Identification of the Escherichia coli murI gene, which is required for the biosynthesis of D-glutamic acid, a specific component of bacterial peptidoglycan.

The murI gene of Escherichia coli, whose inactivation results in the inability to form colonies in the absence of D-glutamic acid, was identified in the 90-min region of the chromosome. The complementation of an auxotrophic E. coli B/r strain by various DNA sources allowed us to clone a 2.5-kbp EcoRI chromosomal fragment carrying the murI gene into multicopy plasmids. The murI gene corresponds to a previously sequenced open reading frame, ORF1 (J. Brosius, T. J. Dull, D. D. Sleeter, and H. F. Noller. J. Bacteriol. 148:107-127, 1987), located between the btuB gene, encoding the vitamin B12 outer membrane receptor protein, and the rrnB operon, which contains the genes for 16S, 23S, and 5S rRNAs. The murI gene product is predicted to be a protein of 289 amino acids with a molecular weight of 31,500. Attempts to identify its enzymatic activity were unsuccessful. Cells altered in the murI gene accumulate UDP-N-acetylmuramyl-L-alanine to a high level when depleted of D-glutamic acid. Pools of precursors located downstream in the pathway are consequently depleted, and cell lysis finally occurs when the peptidoglycan content is 25% lower than that of normally growing cells.

Bacterial Proteins↗
PubMed1988

Presence of carcinogenic glutamic-acid pyrolysis products in human cataractous lens.

The carcinogenic glutamic-acid pyrolysis products, 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1) and 2-amino-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2), were found to be present in human cataractous lenses, but not in normal bovine lenses. Contents of Glu-P-1 and Glu-P-2 in 35 human cataractous lenses were 832 and 20 ng, respectively. These results indicate that the human cataractous lens is exposed to the fluorescent compounds, carcinogenic glutamic pyrolysis products.

Aged↗
PubMed1992

[Glutamic acid as an excitatory neurotransmitter].

The role of L-glutamic acid (Glu) as an excitatory neurotransmitter is reviewed. The idea that Glu is a main excitatory transmitter in the central nervous system (CNS) is now well supported by several lines of evidence, including its excitatory action, presence in the CNS, release, uptake mechanisms and suppression of synaptic transmission by its antagonists. Receptors for Glu are classified into ionotropic and metabotropic receptors. The former is further classified into non-NMDA and NMDA subgroups. The non-NMDA receptor mediates signal transduction between central neurons. Activation of the NMDA receptor causes an increase in intracellular calcium concentration in the postsynaptic neuron and thereby induces plastic changes such as, memory and learning. The function of the metabotropic receptor is yet to be elucidated.

Calcium↗
PubMed2006

A novel drug delivery system for type 1 diabetes: insulin-mimetic vanadyl-poly(gamma-glutamic acid) complex.

Insulin-mimetic vanadyl-poly(gamma-glutamic acid) complex, VO-gamma-PGA, is proposed as a novel drug delivery system for treating type 1 diabetic animals. The structure of VO-gamma-PGA in solution as well as in solid state was analyzed by electronic absorption, infra-red, and electron spin resonance spectra, and proposed that the equatorial coordination mode of VO(2+) is in either carboxylate(O)-VO-(OH(2))(3) or 2 carboxylate(O(2))-VO-(OH(2))(2). In vitro insulin-mimetic activity, metallokinetic feature in the blood of healthy rats, and in vivo normoglycemic effect of the complex prepared in solution were evaluated in streptozotocin(STZ)-induced type 1 diabetic mice, and these effects were compared with those of a solution containing only VOSO(4) as a positive control. The in vitro insulin-mimetic activity of VO-gamma-PGA was examined by determining both inhibition of free fatty acid (FFA) release and glucose uptake in isolated rat adipocytes, in which the concentration of VO-gamma-PGA for 50% inhibition of FFA release was significantly lower than that of VOSO(4). Metallokinetic study suggested that the bioavailability of VO-gamma-PGA complex was much higher than that of VOSO(4). The complex showed a significant hypoglycemic activity within at least 4h after a single oral administration, the effect being sustained for at least 24h. Furthermore, VO-gamma-PGA normalized the hyperglycemia in STZ-mice within 3 days when it was given orally at doses of 5-10mgVkg(-1) body mass for 16 days. The improvement in diabetes was also supported by the results on oral glucose tolerance test, HbA(1c) levels, and blood pressure.

Animals↗
PubMedDate not supplied

Biochemical changes in progressive muscular dystrophy, XVI. Effect of glutamic acid, aspartic acid and glycine on the amino acid content of skeletal muscle of dystrophic mice.

The effect of exogenous administration of glutamic acid (GL), aspartic acid (A) and glycine (G) on individual amino acids in the free amino acid pool was studied in skeletal muscles of 60- to 70-day-old normal (N) and dystrophic (D) mice. Both N and D mice received either 0.25 ml of saline (S) or 250 mg/kg weight of GL, A or G in 0.25 ml S subcutaneously for 13 days. GL, A, G or S did not cause any significant changes in the body and skeletal muscle weights of either group. Most of the individual amino acids were increased in skeletal muscles of GL-treated mice and were decreased in A- or G-treated animals compared to S administration in the N group. The picture was more dramatic in the D group: GL-induced amino acid elevations were more pronounced than the values of N- or S-treated D controls. A and G elicited amino acid increases in D mice compared to their S-treated counterparts. Most of the individual amino acids in skeletal of the D group were decreased relative to N mice after S, GL or A administration. This was evident when the D/N ratio was calculated for S, GL and A. The situation was very different after G administration since of the individual amino acids were augmented in the skeletal muscle of D mice compared to N animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗