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)

Evaluation of morphological alterations at the neuromuscular junction associated with sprouting or other pathological changes has been limited by the inability to visualize simultaneously the multiple cell types that make up a junction. A new combined stain for the concurrent demonstration of motor nerve terminals, cholinesterase, and Schwann cell myelin and other antigens at neuromuscular junctions using bromoindoxyl acetate dye staining for cholinesterase, silver-gold impregnation for nerve terminals, and immunocytochemistry of selected antigens is described. The clarity of the stain permits graphic demonstration of the alteration of neuromuscular junction components during sprouting as well as other pathological changes.
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PMID:Silver cholinesterase immunocytochemistry: a new neuromuscular junction stain. 247 97

Some characteristics of the hydrolysis of O,O-dimethyl-2,2 dichlorovinyl phosphate (DDVP) by human serum are reported and compared with the hydrolysis of O,O-diethyl-4-nitrophenyl phosphate (paraoxon) which is a substrate for Paraoxonase, a known "A"-esterase of human serum. When incubated with human serum, DDVP was losing its inhibitory power toward acetylcholinesterase (AChE). The loss of DDVP followed first order kinetics and was proportional to serum dilution. The disappearance of DDVP after incubation with human serum was not due to protein binding. Apparent Km and Vm for the hydrolysis of DDVP were 7.1 mM and 143 nmol.min-1.ml-1. The pH sensitivity, EDTA inhibitory and Ca2+ requirements of DDVP-ase were similar to those of Paraoxonase. DDVP inhibited the Paraoxonase activity and paraoxon inhibited the DDVP-ase activity. Ca2+, Ag+ and Hg2+ were better inhibitors of the Paraoxonase than the DDVP-ase. The rate of heat inactivation was also different; at 55 degrees Paraoxonase inactivated almost completely within 10 min, while DDVP-ase lost only about 10% activity over 1 hr. Consequently, DDVP-ase and Paraoxonase can be differentiated by means of heat sensitivity. The DDVP-ase was normally distributed in a population of 60 individuals, while Paraoxonase is known to show a marked polymorphism.
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PMID:Human serum "A"-esterases. Hydrolysis of O,O-dimethyl-2,2-dichlorovinyl phosphate. 253 85

This paper describes an indirect method for the quantification of the toxic military agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate (VX) in the vapor state in air or other similar gases at ng/m3 levels. The method begins with the passage of a gaseous sample through a filter impregnated with silver fluoride to convert the VX vapor to ethyl methylphosphonofluoridate. The latter compound is then trapped on a bed of Chromosorb 106, transferred to a smaller bed of the same sorbent, and desorbed thermally into a gas chromatograph equipped with a flame-photometric detector. The method is comparable in sensitivity to the principal alternative method, which is based on cholinesterase inhibition, and it is less subject to interference from common organic solvents and other cholinesterase inhibitors. The detection limit was found to be limited by, and therefore dependent on, the nature and extent of any background substances that produced a significant chromatographic signal or response at the retention time of the analyte. In the absence of such substances, the instrument provided a response to 0.19 ng of VX that was thirty times larger than the peak-to-peak noise amplitude on the chromatographic base line. Moreover, the method bias (i.e., 100% minus the percent VX recovery) was found to depend on VX concentration, with estimates of agent recovery ranging from 83% at a VX concentration of 0.67 ng/m3 to 104% at a concentration of 0.084 ng/m3. The relative standard deviation varied with VX concentration and with the nature of the test that was performed to estimate it. It ranged from 2.1% in one VX vapor-challenge test to 17% in an experiment involving spiked sampling tubes, and it was generally lower at the higher VX test concentrations.
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PMID:Indirect determination of O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate in air at low concentrations. 260 Jan 44

The nerve endings of normal hair of the rat's snout, partially digested with trypsin and hydrochloric acid, were studied by scanning electron microscopy. Each lanceolate structure measured ca. 10 microns in length and was arranged around the hair follicle. These palisade-shaped nerve endings were situated almost beneath the sebaceous glands, ran upward, parallel to the axis of the hair follicle, and terminated in pointed shape. 2 kinds of cells, Teloglia cell Type I showing flat profile, and Teloglia cell Type II showing spherical profile and possessing numerous caveolae in its surface were observed at the basal portion of the palisade-shaped endings. The axon was enclosed by Schwann cells in its course to the hair follicle, and was covered with Type I cells at the beginning, and with Type II cells at the end, and constituted the palisade-shaped nerve endings. The palisade structure in silver impregnated tissues observed by backscattered electron microscopy and X-ray analyzer was characterized as comprising neuronal elements. Cytochemically, the nerve endings showed cholinesterase and Mg-ATPase activities. They may be involved in the reception of the mechanical stimulation of the hair. The palisade nerve endings thus possessed appropriate 3-dimensional structure as mechanoreceptor.
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PMID:Three dimensional observations of the palisade-shaped nerve endings of normal hair of rat's snout. 261 Mar 76

A modified method for improved preservation and optical resolution of acetylcholinesterase (AChE)-containing structures in adult rat brain is described. Optimal tissue preparation included fixation in paraformaldehyde 4%, glutaraldehyde 0.1%, and sucrose 7% in 0.1M Sorensen's phosphate buffer, pH 7.4, rinsing in buffer 50 mM with respect to NH4Cl and 2% with respect to sucrose, acetone dehydration, vacuum infiltration with LKB Historesin, and polymerization at 4 C, overnight incubation of 10 microns sections at 37 C in the AChE histochemical reaction mixture and silver intensification according to Hedreen et al. Demonstration of AChE enzyme activity in the cholinergic projection from the rat basal forebrain to the ipsilateral hippocampus exemplifies the usefulness of the technique. The method provides an excellent demonstration of AChE-positive axonal processes and enables the pharmacohistochemical visualization of cholinergic neurons. This procedure offers a convenient method for analysis of cholinergic neurons that avoids potential artifacts inherent in other AChE histochemical procedures.
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PMID:Optimal parameters for the histochemical demonstration of acetylcholinesterase in plastic sections of rat brain. 262 74

Encapsulated nerve endings in the hairy skin of mice were identified by means of cholinesterase histochemistry. They were especially numerous in the dorsal skin of the ear and where totals ranged from 150 to 597; clustering of corpuscles was an obvious feature. The use of silver impregnation as a counterstain revealed that clusters comprised one or more sets of lamellated corpuscles, each being attached to a single parent axon. The members of each set resembled one another morphologically. Corpuscles from different sets could be classified as simple, branched or coiled. In the hairy skin of cheek, trunk and hindlimb a much lower density of corpuscles was observed; they were all simple in form and occurred in small clusters.
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PMID:Encapsulated nerve endings in murine dorsal ear skin. 263 May 36

Serial cross and longitudinal sections of intrafusal fibers from the intracapsular portions of chicken tibialis anterior muscle spindles were incubated with a monoclonal antibody specific for chicken acetylcholinesterase (AchE) and examined by immunofluorescence for the presence of the enzyme on presynaptic and postsynaptic membranes of neuromuscular junctions. The midequatorial sensory region which lacks organized sarcomeres was negative, but immediately distal to it faintly staining regions of AchE localization were observed on intrafusal fibers. In cross sections at the juxtaequator, the outlines of areas that were positive for AchE were either thin and crescentlike or thick and compact. The distribution of both types of localization continued into the polar region. Toward the more distal polar region, the intensity of sites on the postsynaptic membrane that reacted with the anti-AchE progressively increased. In longitudinal sections, AchE localization was largely limited to two configurations. One was elongate, while the other was more round or oval and often also smaller. Both types might occur on the same, or on different, intrafusal fibers. Examination of silver-impregnated sections revealed the presence of platelike and of traillike axon terminals. The variety of shapes observed on presynaptic and postsynaptic membranes warrants further study to determine whether chicken muscle spindles are innervated by more than one type of motor neuron.
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PMID:Contours and distribution of sites that react with antiacetylcholinesterase in chicken intrafusal fibers. 267 89

Morphological abnormalities of the neuromuscular junction in two murine models with primary myopathy were studied by combined cholinesterase-silver impregnation techniques and electron microscopy. In both situations the results were similar showing that the neuromuscular junction remained unaffected even when innervating necrotic muscle fibres. In regenerated muscle fibres, however, there was marked simplification of the post-synaptic membrane with reduction in number and depth of folds up to 50% of normal values confirmed by morphometric analysis. Since after regeneration succeeded no detectable clinical or physiological alterations were observed in these experiments it seems reasonable to assume that the prominent branching of post-synaptic folds in normal skeletal muscles might represent an increased anatomical safety mechanism in chemical transmission.
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PMID:[Neuromuscular junction changes in experimental myopathies in mice]. 268 4

The pattern of nerves, ganglia, and fine nerve processes in the adult rabbit sinoatrial node, identified by microelectrode recording, was defined by staining histochemically for cholinesterase followed by silver impregnation. A generalized repeatable pattern of innervation was recognized, including 1) a large ganglionic complex inferior to the sinoatrial node; 2) two or three moderately large nerves traversing the sinoatrial node parallel to the crista terminalis; 3) nerves entering the region from the atrial septum, the superior vena cava, and the inferior vena cava; and 4) a fine network of nerve processes, particularly extensive in the morphologically dense small-cell part of the sinoatrial node. When the site of initial depolarization in the node was located and marked by a broken-off electrode tip, it was found, after cholinesterase staining, to be characterized by a cluster of cells enclosed in a nest or basket of fine nerves. Similar nested cell clusters were observed elsewhere in the sinoatrial node in this same preparation and in other hearts. A complex interweaving of atrial muscle fibers was observed medial and inferomedial to the sinoatrial node, which may form the anatomical basis for the lack of conduction through this region. The morphological pattern of nerves, ganglia, and myocardial cells described in this study emphasizes the complexity of innervation of the sinoatrial node, including its intrinsic neural elements. Cholinesterase/silver staining can be useful in the definition and comparison of electrophysiologically identified sites within the sinoatrial node.
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PMID:Morphological study of the innervation pattern of the rabbit sinoatrial node. 278 78

The effects of a prolonged blockade of nerve conduction by tetrodotoxin on frog motor innervation were studied in the cutaneous pectoris muscle of Rana esculenta. Prolonged nerve blockade (up to 22 days) was obtained by repeated subperineural injections of tetrodotoxin. Changes in morphological parameters of neuromuscular junctions were investigated in muscles after staining with a combined cholinesterase-silver method. In addition, changes in the incidence of polyneuronal innervation were investigated conjointly by electrophysiology and morphology. Morphometric analysis of singly innervated muscle fibres of 60 microns diameter revealed insignificant changes during the first week of tetrodotoxin-nerve blockade. After 15 days of paralysis, the mean length of synaptic contacts and the mean length of terminal arborization per synapse were significantly increased as compared to controls (contralateral muscles and citrate buffer-injected controls). After 20-22 days, differences in synaptic and aborization mean lengths were accentuated and reached 44 and 43%, respectively. At that time, the mean number of terminal branching points and of continuous synaptic contacts were also significantly increased (around 20 and 50%, respectively). No changes in the length of abandoned gutters were observed. The incidence of focal polyaxonal innervation (detected morphologically) and of polyneuronal innervation (determined electrophysiologically) was unchanged. The results show that prolonged tetrodotoxin blockade induces sprouting of the terminal arborization which results in an extension of pre-existing nerve terminals and an increase in the complexity of terminal arborization by addition of new branches. Nodal (collateral) sprouting was not changed.
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PMID:Terminal nerve sprouting at the frog neuromuscular junction induced by prolonged tetrodotoxin blockade of nerve conduction. 278 62


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