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)

1. The second-order rate constants of inhibition, k(a), of acetylcholinesterase were measured at pH values between 5.5 and 10.5 for two esters of phosphorus acids and five esters of carbamic acids. Two of the carbamates and one of the phosphates contained a quaternary nitrogen group. 2. For the three positively charged compounds the k(a)-pH plots are bell-shaped, with a pH optimum between 7.5 and 9.0. The changes in k(a) above and below the optimum pH fit theoretical curves for the dissociation of groups on the protein of pK 6.2 and 10.25. 3. For the uncharged compounds, the k(a)-pH plot on the alkaline side is identical with the one obtained for charged inhibitors. On the acid side they do not fit such a curve and the k(a) for two of the carbamates is independent of pH changes between 5.5 and 8.0. 4. The first-order rate constants, k(+3), for spontaneous reactivation were measured at pH values between 5.0 and 11.0 for N-methylcarbamoylated, NN-dimethylcarbamoylated and di-(2-chloroeth)phosphorylated cholinesterase. For all three derivatives the k(+3)-pH plots are bell-shaped, with a pH optimum between 8.0 and 8.5. The changes in k(+3) above and below the optimum fit theoretical curves for the dissociation of groups of pK 6.9 and 9.8. 5. The relevance of these results to binding, acylation and deacylation of both inhibitors and substrates is discussed.
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PMID:Effect of pH on inhibition and spontaneous reactivation of acetylcholinesterase treated with esters of phosphorus acids and of carbamic acids. 607 Jan 26

The purpose of the present investigation was to identify and compare cholinergic intramural neurons in the lower esophageal sphincter and esophageal body by histochemical staining for acetylcholinesterase and the enzyme that synthesizes acetylcholine, choline acetyltransferase. Opossums were anesthetized and their abdominal cavity was opened by a midline incision to expose the esophagogastric junction. The lower esophageal sphincter was identified manometerically and localized in situ with markers. Tissues were removed, rapidly frozen in freon cooled with liquid nitrogen and serial cryostat sections were obtained from the lower esophageal sphincter and esophageal body. Sections were stained with one of the above histochemical procedures and adjacent sections were stained with Solachrome cyanin , which differentially stains nerve elements from muscle fibers. The muscle of the lower esophageal sphincter and esophageal body was stained with nonspecific cholinesterase with some selectivity of intensity of reaction in the various smooth muscle layers. All identifiable plexus neurons in the esophagus stained for nonspecific cholinesterase and acetylcholinesterase. Nerve fiber tracts were also stained for acetylcholinesterase within the longitudinal and circular layers of the tunica muscularis. Reaction for choline acetyltransferase showed no staining in the muscle layers or nerve fiber tracts of either part of the esophagus studied; however, selected neurons within the myenteric plexus of both regions (approximately 38%) were reactive. There was no significant difference in the number of positive choline acetyltransferase neurons in the lower esophageal sphincter or esophageal body.
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PMID:Acetylcholinesterase and choline acetyltransferase staining of neurons in the opossum esophagus. 620 39

A clinical and serological study was performed on 267 of 636 volunteers vaccinated against Argentine hemorrhagic fever with the XJCl3 attenuated strain of Junin virus seven to nine years earlier, in order to determine their long-term evolution. This study included a clinical examination, a chest roentgenogram, an electrocardiogram, and the following laboratory determinations: white and red cell count, number of platelets, hematocrit, hemoglobin, sedimentation rate (Katz index), urea, nitrogen, glucose concentration, cholesterol, GOT, GPT, gamma GT, alkaline phosphatase, cholinesterase, and total bilirubin. Neutralization reactions were performed to determine presistence of antibody levels. All clinical and laboratory findings were within normal limits, excluding a long-term pathology attributable to the virus. Of 165 tested sera, 153 (90.3%) had detectable levels of neutralizing antibodies, and the rest had no antibodies after this time. Although these people live in the endemic area, it is considered that only the 9% that had increased antibody levels had suffered a reinfection during the seven- to nine-year period, which acted as a booster. This figure aproximately coresponds to the subclinical infection value found in the region. In the rest, the persistence of antibodies is attributed to the immunization achieved with the vaccine employed.
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PMID:Immunogenicity of A/USSR (H1N1) subunit vaccine in unprimed young adults. 627 Feb 79

Intraocular grafts of rat hippocampal tissue, grafted either directly from the immature donor brains (fresh) or after storage in liquid nitrogen at -196 degrees C (freeze-stored), were compared with regard to survivability and histological and connective organization. For direct grafting, pieces of hippocampal tissue from rat embryos (embryonic day 19, E21) and newborn rats (PO) were placed in the anterior eye chamber of adult rats immediately after dissection. For grafting after deep-freeze storage, pieces of hippocampal tissue were taken from rat embryos (E16-E21) and newborn rats (PO), frozen at a cooling rate of 1 degrees C/min in CO2 or N2 vapours after addition of the cryoprotective agent dimethylsolfoxide (DMSO), and stored in liquid nitrogen for 1 to 33 days before thawing and intraocular grafting. From 20 to 68 days after grafting, the recipient rats were sacrificed, their eyes sectioned, and the sections stained with thionine for cell bodies, Timm's sulphide silver method for hippocampal fiber systems and terminal fields, and acetylcholinesterase (AChE) for cholinergic fibers and AChE-positive neurons. When examining the 101 grafted eyes (34 grafted with fresh and 67 with freeze-stored tissue) a significantly lower survival rate of the freeze-stored tissue was found (28 vs. 88%). The survivability of the freeze-stored tissue was age-dependent with no survival at donor ages E16 and PO, while tissue from E18-E21 had a 50% survival rate. The grafts of the freeze-stored tissue were also smaller and showed an increased tendency for fragmentation. When evaluating the structure of the grafts, the deep-freeze storage was found primarily to have been harmful to the dentate granule cells and their precursors. The organization of intrinsic fiber connections followed the pattern known from lesion and intracerebral transplant studies. While demonstrating that immature brain tissue can survive deep-freeze storage and subsequent intraocular grafting, the study also indicates that different schemes may have to be used to get optimal survival of different neuronal populations.
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PMID:Intraocular grafts of fresh and freeze-stored rat hippocampal tissue: a comparison of survivability and histological and connective organization. 647 Feb 22

To determine the effects of low-dosage organophosphate administration on exercise in a hot environment, malathion (7.5 mg/day, 4 days) was administered IP to rats, and effected a 35% (p less than 0.01) reduction in plasma cholinesterase levels. Treadmill endurance (9.14 m/min, no incline, 35 degrees C ambient) was unaffected when the animals were exercised to hyperthermic exhaustion (Tre approximately 43 degrees C). While rates of heat gain were similar between groups, malathion-treated rats displayed higher Tsk (p less than 0.05) at a number of sampling times during the treadmill run. While creatine phosphokinase levels were unaffected by either cholinesterase inhibition or exercise in the heat, lactate dehydrogenase activities were increased (p less than 0.01) in both groups following hyperthermic exhaustion. Although plasma levels of lactate, potassium, urea nitrogen, and creatinine were all significantly (p less than 0.01) increased as a result of exercise in the heat, these increments were not exacerbated by cholinesterase inhibition. Results generally indicated that at this moderate level cholinesterase inhibition, malathion administration did not adversely affect physiological, physical, or thermoregulatory efficacy.
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PMID:Malathion administration: effects on physiological and physical performance in the heat. 665 21

Adult, male rats (300-325 g) were treated with pyridostigmine bromide (n = 22) or saline (n = 22) to quantitate the effects of cholinesterase inhibition (64%) on the ability to work (9.14 m/min, level treadmill) in the heat (35 degrees C). Pyridostigmine-treated rats had a mean endurance of 23 min, whereas saline-treated animals ran for nearly 35 min (P less than 0.001). Rates of rectal and skin temperature increments were significantly higher (P less than 0.001) in pyridostigmine-treated rats as were water losses (P less than 0.001). Exercise in the heat to hyperthermic exhaustion effected anticipated increments in circulating urea nitrogen, creatinine, lactate dehydrogenase, and potassium levels, whereas pyridostigmine pretreatment had additive effects on lactate and creatine kinase concentrations. Additionally, pyridostigmine elicited a significant (P less than 0.01) hyperglycemia before exercise, an effect noted also with other organophosphate simulants. We concluded that pyridostigmine-induced cholinesterase inhibition had a variety of debilitating effects during work in the heat.
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PMID:Effects of pyridostigmine on ability of rats to work in the heat. 672 66

The specific modifiers of the carboxylic groups - 1.3-dicyclohexylcarbodiimide (DCC) and 1-cyclohexyl-3-(2-morpholinyl-4-ethyl)carbodiimide methyl-p-toluenesulfonate (CMC) cause irreversible inhibition of acetylcholinesterase from human erythrocytes (AChE) and butyrycholinesterase from horse blood serum (BuChE). The rate of hydrolysis of both acetylcholine and non-charged substrates - phenylacetate and indophenylacetate - is thereby decreased. At initial steps of the reaction the irreversible inhibition obeys the kinetics of the pseudo-monomolecular reactions with the following values of bimolecular constants for the rates of DCC and CMC reactions: for AChE - 2.3 +/- 0.19; 5.1 +/- 0.23 M-1 min-1, for BuChE - 1.5 +/- 0.14 and (2.2 +/- 0.21) . 10(2) M-1 min-1 (25 degree, pH 7.5). The morpholinyl carbodiimide with a quaternary nitrogen. a more specific inhibitor of cholinesterases, which is of a mixed (Ki = (3.0 +/- 0.21) . 10(-4) M for AChE) and of competitive (Ki = (3.3 +/- 0.24) . 10(-5) M for BuChE) type. Under AChE modification by CMC at concentrations causing 50 - 70% inhibition, the substrate inhibition constants and the thermal stability of the non-inhibited part of the enzyme are increased. The role of functional groups of the catalytic and regulatory centers of cholinesterases in the chemical modification by carbodiimides is discussed.
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PMID:[Effect of carbodiimides on the catalytic properties of cholinesterases]. 694 38

The contents of a bottle, from which a human being was reported to have drunk and which were believed responsible to an organophosphorus poisoning, were submitted for chemical analysis. Initial screening by gas chromatography with phosphorus, sulfur, and nitrogen specific detectors failed to identify any intact organophosphorus pesticide. Mass spectrometric techniques were applied to the identification. Field ionization, field desorption, chemical ionization, exact mass measurements at high resolution, and GC/low resolution mass spectrometry were used to help define the qualitative and partial quantitative nature of the sample components. Results of this study were consistent with the virtually complete conversion of the pesticide, diazinon [Chemical Abstracts reference number 333-41-5], into a mixture of at least twenty-six chemically distinct products or impurities. The most abundant chemical compounds found in the sample included: 2-isopropyl-4-methyl-6-hydroxypyrimidine [2814-20-2]; 2-isopropyl-4-methyl-6-mercaptopyrimidine; 6,6'-dithiobis-(2-isopropyl-4-methylpyrimidine); 6,6'-dithiobis-(2-isopropyl-4-methylpyrimidine); 4-ethoxy-2-isopropyl-6-methylpyrimidine [72799-31-6]; 4-thioethoxy-2-isopropyl-6-methylpyrimidine; triethylphosphorothiolate and triethylphosphorothiolate. Also found were several potent acetylcholinesterase inhibitors: monothionotetraethylpyrophosphate; dithionotetraethylpyrophosphate [3689-24-5]; tetraethylpyrophosphate. Model decomposition studies verified the formation of these compounds. These results were then used to identify compounds in two other samples.
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PMID:The recognition of diazinon, an organophosphorus pesticide, when found in samples in the form of decomposition products. 724 25

Stress as well as anesthesia has been reported to stimulate endorphin release. The possibility that the stress of compression at 1 atm/min or nitrogen anesthesia, or both, might release endorphins was tested in guinea pigs with the use of naloxone--a narcotic antagonist, and physostigmine--a cholinesterase inhibitor. The animals received i.p. equal volumes of either drugs or the placebo just before compression to 32 ATA (oxygen less than or equal to 1 ATA). The pressure at loss of righting reflex was compared. Nitrogen anesthesia occurred at mean pressures ranging from 26.9 to 27.8 ATA, with no statistical differences demonstrated in all groups. It is concluded that 1) neither naloxone nor physostigmine reversed nitrogen narcosis and 2) stress of compression or nitrogen narcosis, or both, failed to show effects attributable to increased endorphin release.
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PMID:Failure of naloxone or physostigmine to reverse nitrogen anesthesia in guinea pigs. 729 86

We studied the effects on 25 analytes of duration of contact of serum with non-anticoagulated blood and of temperature. Serum was separated after blood was allowed to stand, for 0, 2, 4, 6, 8, 24, or 48 h at 4, 23, or 30 degrees C. Results obtained for bilirubin, albumin, zinc sulfate turbidity, thymol turbidity, cholinesterase (EC 3.1.1.8), alkaline phosphatase (EC 3.1.3.1), leucine aminopeptidase (EC 3.4.11.1), amylase (EC 3.2.1.2), total cholesterol, triglycerides, beta-lipoprotein, serum urea nitrogen, creatinine, uric acid, and gamma-glutamyltransferase (EC 2.3.2.2) were not influenced by storage at 4, 24, or 30 degrees C for as long as 48 h. Negligible differences were seen for potassium in sera in contact with cells as long as 24 h at 23 degrees C and for inorganic phosphorus after 48 h at 4 degrees C. However, at 4 degrees C we noted an increase at 8 h, a slight decrease at 30 degrees C. Statistically significant changes were seen for total protein and calcium after 48 h at 30 degrees C; for aspartate aminotransferase (EC 2.6.1.1), and alanine aminotransferase (EC 2.6.1.2), between 8 and 24 h at 23 degrees C and as soon as 6 h at 30 degrees C; for lactate dehydrogenase (EC 1.1.1.27) after 8 h at 30 degrees C and between 8 and 24 h at 23 degrees C; for glucose at 24, 4, or 2 h of storage at 4, 23, or 30 degrees C, respectively; for inorganic phosphorus after 48 h at 23 degrees C or 8 h at 30 degrees C; for potassium after 4 h at 4 degrees C or 24 h at 30 degrees C; and for sodium after 48 h at 4 degrees C or 6 h at 23 or 30 degrees C.
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PMID:Serum-constituents analyses: effect of duration and temperature of storage of clotted blood. 744 20


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