Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activity of the following enzymes in clinically normal newborn calves was investigated: glutamate-oxalacetate transaminase (GOT), glutamate-pyruvate transaminase (GPT), alkaline phosphatase (APh), creatine phosphokinase (CPhK), lactate dehydrogenase (LDH), leucine-aminopeptidase (LAP), aldolase (A), and cholinesterase (ChE). The studies were carried out at the first hour prior to offering colostrum as well as at the 6th, 12th, 24th hr and on the 2nd, 3rd, 4th, 5th, 7th, 10th, 15th, and 20th day following it first intake. Regularly rising values of the enzyme activity up to the 24th hour were observed with APh, GOT, GPT, CPhK, and LAP. The aldolase enzyme (after colostrum had been given for the first time) in all animals showed a statistically significant drop of activity at the 6th hour. The activity of LDH displayed a consistently rising trend up to the end of the experimental period. The cholinesterase activity showed high values immediately following birth, reaching those found in the dams by the end of the observation period.
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PMID:[Dynamics of some serum enzymes in the postnatal development of calves]. 94 95

Following the implantation of cobalt-gelatine pellets into the frontal cortex, epileptiform spikes in both primary and secondary foci developed and reached a peak between 7-12 days post implantation. Histological examination showed a necrotic lesion with terminal and fibre degeneration in brain areas connected with the frontal cortex. Golgi staining at 60 days showed a loss of pyramidal cells in the primary focal area. In the lesion and primary focal areas GABA, glutamate and aspartate were significantly reduced between 5--10 days post implantation. No changes in glutamine and glycine were found in either the lesion or pulmonary focus. No changes in amino acid content were found in the secondary focus or in glass implanted controls at any time. In cobalt-treated rats there were significant reductions in the transmitter related enzymes, glutamate decarboxylase, acetylcholinesterase, choline acetyltransferase and aromatic amino acid decarboxylase in the lesion area and primary and secondary foci at 4--8 days post implantation. Levels of these enzymes had recovered to normal by 24 days. Lactate dehydrogenase was reduced only in the lesion area. Beta-Galactosidase was reduced in the lesion area at 4 days but subsequent rose rapidly paralleling increasing gliosis around the lesion. It is concluded that cobalt-induced epilepsy is associated with relatively selective loss of neuronal tissue and provides a useful model for further investigation relevant to clinical epilepsy.
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PMID:Neurochemical and morphological changes during the development of cobalt-induced epilepsy in the rat. 113 20

The effects of histamine acid phosphate and selected antihistamines, both separately and together are studied on the enzyme-substrate relationships of glutamate dehdrogenase and acetylcholinesterase of sheep liver and brain homogenates.
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PMID:Histamine and selected antihistamine regulation of glutamate dehydrogenase and acetylcholinesterase in sheep and medulla oblongata. 115 18

The purpose of this study was to determine whether denervation supersensitivity could be produced in an identified cholinergic pathway in the CNS of the rat. The mechanism for the development of this phenomenon was also explored. Cholinergic denervation of the hippocampus was accomplished by lesions of the medial septum. The response of hippocampal pyramidal cells to microiontophoretic application of acetylcholine (ACh) and carbachol in lesioned and unlesioned animals was determined by extracellular recording. There was a marked increase (6 X) in sensitivity to ACh 2-43 days following lesions. However, there was no increase in sensitivity to carbachol or glutamate. Other workers have shown that septal lesions cause a large decrease in hippocampal acetylcholinesterase (AChE) which is located mainly presynaptically. The absence of increase in sensitivity to carbachol, a cholinomimetic resistant to hydrolysis by AChE, suggests that the postlesion increase in sensitivity to ACh results from a decrease in its inactivation by AChE. A time course for the development of ACh supersensitivity was found to be similar to the time course of AChE loss previosly reported. Experiments using physostigmine, an AChE inhibitor, demonstrated that inhibition of AChE can potentiate the effects of ACh in unlesioned preparations, but not in lesioned preparations. We conclude: (1) denervation supersensitivity to ACh occurs in the septo-hippocampal pathway; and (2) the supersensitivity is probably due to decreased inactivation of ACh by AChE. The results suggest that presynaptic AChE plays a significant role in modulating the neurotransmitter function of ACh in the septo-hippocampal pathway.
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PMID:Denervation supersensitivity in the cholinergic septo-hippocampal pathway: a microiontophoretic study. 119 81

In the group of 107 patients poisoned by carbon monoxide (18 patients), ethanol (10), barbiturates (18), glutehimide (10), tranquilizers (19), organic solvents (10),salicylates (3), organochlorines (8), and sulfonamides (5)--the activities of 8 serum enzymes were determined for 6 consecutive days of treatment, the enzymes being as follows: aminotransferases, cholinesterase, alkaline phosphatase, lactate, alpha-hydroxybutyrate, glutamate, and sorbitol dehydrogenase. The antipyrine half-life was also assayed. It has been shown that the poisonings by particular groups of poisons do not bring about characteristic changes in the activity of enzymes that might be of any diagnostic value. The intensity of changes was connected withe depth and duration of toxic coma. Most frequently an increase ensued in the activity of AspAt and AlAt in the third 24-hrs period, and an increase in the activity of SDH in the first 24-hrs period. In the group under examination there were 26 drug abusers in whom a shortening of the antipyrine half-life was discovered. They were less responsive to toxic doses of drugs, and the enzymatic changes in them were less distinct. No changes in the activity of tested enzymes, which are characteristic of toxicomania, were found.
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PMID:The usefulness of the enzymatic tests in acute poisonings. 124 89

Acetylcholinesterase is released in a calcium-dependent manner when afferents of the cerebellar cortex are stimulated. Since cholinergic transmission is probably insignificant in the cerebellar cortex, the esterase itself might serve as a transmitter or modulator. Therefore, the effect of acetylcholinesterase in the cerebellum was investigated in slices of guinea-pig cerebella during intracellular recording from Purkinje cell somata or dendrites. Addition of acetylcholinesterase (20 U/ml) to the superfusion medium did not change the membrane potential or the input resistance of the Purkinje cells. Thus, esterase does not act like a classical transmitter. The threshold for Na+ spikes generated by intracellular current injection was unaffected, but the threshold for Ca2+ spikes was increased. This increase was abolished by tetrodotoxin (1 microM). Furthermore, when Ca2+ currents were blocked by substituting Mn2+ for Ca2+ (2 mM) a decrease in a Na+ plateau potential was seen in the presence of esterase. The effect of acetylcholinesterase of Ca2+ spikes is therefore most likely due to a reduction of the non-inactivating Na+ current of the Purkinje cell membrane. When present this current contributes to activation of Ca2+ spikes in dendrites. Acetylcholinesterase also enhanced the response of Purkinje cells to the excitatory amino acids glutamate and aspartate thought to be transmitters in the cerebellar cortex. The responses became larger and faster in the presence of esterase. Responses to climbing fibre stimulation were also enhanced by acetylcholinesterase. The late part of this synaptic response was increased. The potentiation by esterase of responses of Purkinje cells to excitatory amino acids and to climbing fibre stimulation may be mediated through interference with transmitter uptake, because it was prevented by treatment with DL-2-amino-4-phosphonobutyric acid (0.5 mM) and di-hydrokainate (0.1 mM). None of the effects of esterase was due to hydrolysis of acetylcholine because irreversible inhibition of the catalytic site of the enzyme with soman did not prevent the actions. The observations were specific for acetylcholinesterase. Butyrylcholinesterase (20-40 U/ml) showed none of the effects. It is concluded that acetylcholinesterase in the cerebellar cortex seems to mediate a novel type of modulation by two separate mechanisms. Esterase reduces the tendency towards Ca2+ spike generation in Purkinje cells. Ca2+ spikes are followed by afterhyperpolarizations and in their absence firing of Na+ spikes at higher frequencies is possible. Secondly, there is an enhancement of the action of excitatory transmitters so that the extended operating range can be utilized.
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PMID:Actions of acetylcholinesterase in the guinea-pig cerebellar cortex in vitro. 135 19

The glycophospholipid-linked, amphiphilic form of acetylcholinesterase (AChE) from Torpedo californica and the hydrophilic form from mouse were overexpressed in Sf9 insect cells using the baculovirus expression system. Recombinant baculovirus, constructed by inserting AChE cDNA's into the genome of Autographa californica nuclear polyhedrosis virus adjacent to the strong polyhedron promoter, yielded recombinant enzyme varying between 0.5 and 3.8 mg/L. The recombinant enzyme was glycosylated although it migrated slightly more rapidly in SDS gel electrophoresis than enzyme purified from the electric organ of Torpedo. Kinetic properties of the recombinant DNA- and tissue-derived enzymes are identical. The detailed catalytic properties and susceptibility to inhibitors were examined for two enzyme mutations of the glutamate residue N-terminal to the active site serine. The Glu199 to Gln mutation shifted both the Km and Kss to higher substrate concentrations and resulted in a kcat of 28% of the wild type. Mutation of Glu199 to Asp also yielded a reduction in kcat but with no change in Km. Substrate inhibition normally apparent in wild-type AChE was eliminated with the Asp mutation, suggesting that substrate catalysis and substrate inhibition are not directly linked. Both mutations decreased the affinity of reversible inhibitors and reduced the rates of phosphorylation and carbamoylation; these changes were more striking with the Gln199 mutation. Decarbamoylation rates were unaffected by these mutations. Glu199 is the charged residue found deep within the active center gorge close to the site of acetylcholine binding, and our findings indicate it influences, but is not essential for, efficient catalysis.
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PMID:Expression of recombinant acetylcholinesterase in a baculovirus system: kinetic properties of glutamate 199 mutants. 135 36

The changes in extracellular acetylcholine and glutamate levels were determined, during the course of seizures induced by soman, an irreversible inhibitor of acetylcholinesterase, in the CA1 hippocampal area of rats previously injected with atropine or normal saline into septum. The marked increases observed in soman-treated animals were abolished in rats receiving atropine. These data strongly suggest that, during soman intoxication, septal cholinoceptive cells play a key role in controlling the release of acetylcholine and glutamate in hippocampus. The mechanisms underlying this phenomenon are discussed.
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PMID:Changes in hippocampal acetylcholine and glutamate extracellular levels during soman-induced seizures: influence of septal cholinoceptive cells. 135

This paper reviews chemical models of epilepsy and their relevance in the identification and characterization of anticonvulsants. For each convulsant we discuss possible modes of administration, clinical type(s) of seizures induced, proposed mechanism(s) of epileptogenesis and, where available, responsiveness of the induced seizures to anticonvulsants. The following compounds are reviewed: pentylenetetrazol, bicuculline, penicillin, picrotoxin, beta-carbolines, 3-mercaptopropionic acid, hydrazides, allylglycine; the glycine antagonist strychnine; gamma-hydroxybutyrate; excitatory amino acids (glutamate, aspartate, N-methyl-D-aspartate, quisqualate, kainate, quinolinic acid); monosubstituted guanidino compounds, metals (alumina, cobalt, zinc, iron); neuropeptides (opioid peptides, corticotropin releasing factor, somatostatin, vasopressin); cholinergic agents (acetylcholine, acetylcholinesterase inhibitors, pilocarpine); tetanus toxin; flurothyl; folates; homocysteine and colchicine. Although there are a multitude of chemical models of epilepsy, only a limited number are applied in the routine screening of potential anticonvulsants. Some chemical models have a predictive value with regard to the clinical profile of efficacy of the tested anticonvulsants. Some chemical models may contribute to a better understanding of possible mechanisms of epileptogenesis.
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PMID:Chemical models of epilepsy with some reference to their applicability in the development of anticonvulsants. 139 44

Extracellular acetylcholine (ACh) levels were determined, by intracranial microdialysis, in medial septum, amygdala and hippocampus (CA1, CA3, dentate gyrus) of rats during seizures induced by systemic administration of soman (pinacolyl methylphosphonofluoridate), a potent inhibitor of acetylcholinesterase (AChE). In all septo-hippocampal areas a two phase variation was observed: a primary increase in ACh during the pre-seizures period, followed by a decline after 10 to 20 min of seizures and then a second release at 50 min of seizures. In amygdala a progressive increase of the ACh level reached a maximal value at 50 min. ACh levels than returned to basal values in all areas. Hippocampal AChE activity remained totally inhibited throughout the experiment. Possible dynamic phenomena underlying these variations (blood-brain barrier opening, autoregulation of release) are suggested. The present results are compared to previous reports about glutamate changes in the same areas during soman seizures. This comparison gives evidence that in septo-hippocampal areas the glutamatergic system is recruited after an early accumulation of extracellular ACh. The respective roles of ACh and glutamate in triggering and maintenance of soman seizures activity are discussed.
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PMID:Extracellular acetylcholine changes in rat limbic structures during soman-induced seizures. 147 60


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