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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Chicken muscle and retina, and rat muscle asymmetric acetylcholinesterase (AChE) species were bound to immobilized heparin at 0.4 M NaCl. Binding efficiency was between 50 and 80% for crude fraction I A-forms (A1; muscle), and nearly 100% for fraction II A-forms (A11; muscle and retina). Antibody-affinity-purified A1-forms (chicken) were, however, quantitatively bound to heparin–agarose gels, whereas diisopropylfluorophosphate-inactivated high-salt extracts partially prevented the binding of both A1 and A11 AChE forms, thus suggesting the presence in crude A1 extracts of heparin-like molecules interfering with the tail–heparin interaction. All bound A-forms were progressively displaced from the heparin–agarose columns by increasing salt concentrations, with maximal release at about 0.6 M. They were also efficiently eluted by heparin solutions (1 mg/ml), other glycosaminoglycans being much less effective. Chicken globular AChE forms (G-forms, both low-salt-soluble and detergent-soluble) also bound to immobilized heparin in the absence of salt. Stepwise elution with increasing NaCl concentrations showed maximal release of G-forms at 0.15 M, all globular forms being totally displaced from the column at 0.4 M NaCl. Heparin (1 mg/ml) had the same eluting capacity as 0.4 M NaCl, whereas other glycosaminoglycans were only marginally effective. We conclude that the molecular forms of AChE in these vertebrate species interact with heparin, at salt concentrations that are characteristic for asymmetric and globular forms. Within the A and G molecular form groups, no differences were found in the behavior of the different fractions or subtypes, provided that the enzyme samples were free of interfering molecules. If heparin affinity reflects the ability of AChE forms to interact with extracellular matrix components, not only asymmetric but also some globular enzyme forms could be bound to basal laminae under physiological ionic strength conditions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 66 (1996), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Acetylcholinesterase (AChE), a highly conserved enzyme in the animal kingdom, is distributed throughout a wide range of vertebrate tissues where it is expressed as multiple molecular forms comprising different arrangements of catalytic and structural subunits. The major AChE form in the CNS is an amphiphilic globular tetramer (G4 AChE) consisting of four identical catalytic subunits attached to cellular membranes by a hydrophobic noncatalytic subunit (P-subunit). This study focuses primarily on current data involving the structure of the G4 AChE P-subunit, the expression and regulation of G4 AChE during development and adulthood, and its role(s) in certain neurological disorders including Alzheimer's disease.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The present work addresses the effects of shortterm denervation on acetylcholinesterase (AChE; EC 3.1.1.7) isoenzymes in anterior gracilis muscles from adult male Sprague-Dawley rats. It examines possible relationships between AChE isoform changes and other denervation phenomena, and evaluates the importance of acetylcholine (ACh)-nicotinic receptor interactions in selectively modulating the activity of G4 AChE. Results confirm that denervation causes a specific, transient increase in G4 AChE and show that: most of the increment can be explained by the hydrophobic species of this isoenzyme; changes in AChE isoforms markedly precede the onset of spontaneous electromechanical activity (fibrillation), as well as acetylcholine receptor (AChR) proliferation; and the G4 AChE response is eliminated when AChRs are blocked by α-bungarotoxin treatment performed before but not after (24 h) denervation. These data point to the absence of direct causal relationships between the G4 AChE increment and fibrillation, AChR proliferation, or changes in the release of this isoform from denervated muscle. In turn, they suggest the participation of AChR activation in triggering the G4 AChE response and emphasize the possible role of ACh-AChR interactions in modulating the production of this isoenzyme in not only denervated but also innervated fast-twitch muscles.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 53 (1989), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Acetylcholinesterase (AChE; EC 3.1.1.7) isoenzymes in gracilis muscles from adult Sprague-Dawley rats were studied 24–96 h after obturator nerve transection. Results show a selective denervation-induced increase in the globular G4 isoform, which is predominantly associated with the plasmalemma. This enzymatic increase was (a) transient occurring between 24 and 60 h) and accompanied by declines in all other identifiable AChE isoforms; (b) observed after concurrent denervation and inactivation of the enzyme with diisopropylfluorophosphate, but not following treatment with cycloheximide; and (c) more prominent in the extracellular compartment of muscle endplate regions. Aside from this transient change, G4 activity did not fall below control levels, indicating that at least the short-term maintenance of G4AChE (i.e., at both normal and temporarily elevated levels) does not critically depend on the presence of the motor nerve. In addition, this isoform's activity increases in response to perturbations of the neuromuscular system that are known to produce elevated levels of acetylcholine (ACh), such as short-term denervation and exercise-induced enhancement of motor activity. The present study is consistent with the hypothesis that individual AChE isoforms in gracilis muscle are subject to distinct modes of neural regulation and suggests a role for ACh in modulating the activity of G4 AChE at the motor endplate.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 35 (1980), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The effects of certain protease inhibitors on end-plate acetyl-cholinesterase (AChE) activity, as well as on wet weight and total protein, were studied in vivo in intact and denervated anterior gracilis muscles from the rat. A combination of leupeptin, pepstatin, and aprotinin, administered intraarterially, partly prevented the early (24 h) denervation-induced decrease in muscle weight and protein content. In turn, leupeptin and aprotinin, either alone or in combination, markedly reduced the decay of AChE activity in the denervated muscles, whereas pepstatin alone was ineffective. Such effects were additive in that the inhibitors in combination were more effective than when they were used separately. Additional experiments indicated that none of the inhibitors, at the concentrations used, affected AChE activity directly, nor did they have a significant effect during processing of the muscle samples. These findings indicate that the initial decay of AChE activity with denervation was effectively reduced by the inhibitors, probably through inactivation of proteolytic enzymes which, otherwise, would be increased in denervated muscle.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 32 (1979), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Multiple molecular forms of acetylcholinesterase (AChE; EC 3.1.1.7), in crude extracts of various tissues from the rat, were distinguished by velocity sedimentation analysis on linear sucrose gradients. Skeletal muscle samples containing end-plate regions showed three different forms of AChE with apparent sedimentation coefficients of 16, 10 and 4s. The 16s form was not detected in non-innervated regions of skeletal muscle, large intestine smooth muscle, whole brain tissue, red blood cells or plasma. Spinal cord, a predominantly motor cranial nerve and mixed (sensory and motor) peripheral nerves contained 16, 10, 6.5 and 4S AChE. Ventral motor roots, supplying the sciatic nerve, contained these four forms of the enzyme, while corresponding dorsal sensory roots were devoid of the 16S form. The 16s-AChE confined to ventral roots can be attributed totally to motor neurons and not to Schwann cells composing these roots. Whether the 16s-AChE presently found in motor nerves has chemical identity with that found at motor end-plates is the basis of future experiments.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 262 (1976), S. 55-56 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Effect of axoplasmic transport blockage (?) and denervation (D) on AChE activity, in cat geniohyoid muscle. Muscle regions containing endplates were homogenised 1/50 (w/v) in ice-cold NaCl?Triton buffer, pH 7.3 (1 M NaCl, 0.1 % Triton X-100, 0.05 M Tris-HCl, 0.2 mM EDTA). AChE activity as ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurocytology 14 (1985), S. 795-808 
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cytochemically stained acetylcholinesterase (AChE) activity in endplate regions of adult rat gracilis muscles was studied afterin situ treatment with AChE inhibitors which differ in lipid solubility and hence in their ability to penetrate cell membranes. Control preparations showed intense AChE staining over junctional infoldings and within myofibres, but little enzymatic reaction product in nerve terminals and Schwann cells. Echothiophate (poorly lipid soluble) drastically reduced only extracellular AChE activity, whereas sequential treatment with BW284C51 (poorly lipid soluble) and diisopropylfluorophosphate (lipid soluble) primarily eliminated intracellular AChE. Extracellular AChE activity (associated with the synaptic basal lamina) was predominantly composed of asymmetric enzymatic forms. Intracellular AChE (associated with the sarcoplasmic reticulum of the myofibres) primarily contained globular forms and a small proportion of asymmetric forms. Little or no external AChE activity was detected in non-endplate muscle regions and the internal enzyme was confined to a restricted subcellular region close to the point of innervation. These results establish the validity of using the abovein situ pharmacological treatments to demonstrate intracellular and extracellular pools of AChE in adult skeletal muscles. In addition, they are consistent with the idea that motor neurons play an essential role in the mechanisms which determine the subcellular distribution of AChE.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-7381
    Keywords: Nerve ; colchicine ; axoplasmic transport ; fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study is concerned with the effect of colchicine on the structure of fibrillar constituents of neurons and on the transport of neuronal organelles. Colchicine was injected beneath the perineurium of the hypoglossal nerve. Close to the site of the injection, the 24 and 48 h experimental axons showed loss of microtubules, increased numbers of filaments and increased amounts of the microfilamentous material bridging the filaments. Evidence of organelle damming was found proximal to the site of the injection. Five days after the injection of colchicine the nerves appear to have recovered and resemble control nerves. It is speculated that the circumscribed increase in the amount of filaments and microfilaments may produce a ‘gel barrier’ that interrupts mechanically the movement of organelles.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The characterization of individual acetylcholinesterase (AChE) molecular form subcellular pools in adult mammalian skeletal muscle is a critical point when considering such questions as the origin, assembly, and neurotrophic regulation of these molecules. By correlating the results of differential extraction, in vitro collagenase digestion, and in situ pharmacologic probes of AChE molecular forms in endplate regions of adult rat anterior gracilis muscle, we have shown that: 1) 4.0S (G1) and 6.0S (G2) AChE are predominantly membrane-bound and intracellular; if an extracellular and/or soluble fraction of these forms exists, it cannot be adequately resolved by our methods; 2) 9–11S (globular) AChE activity is distributed between internal and external pools, as well as membrane-associated and soluble fractions; 3) 16.0S (A12) AChE is not an integral membrane protein and exists both intracellularly (25–30%) and extracellularly (70–75%).
    Type of Medium: Electronic Resource
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