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  • 1
    Electronic Resource
    Electronic Resource
    Head group modulation of membrane fluidity in sonicated phospholipid dispersions (1974)
    s.l. : American Chemical Society
    Biochemistry 13 (1974), S. 2605-2612 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00709a021
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  • 2
    Electronic Resource
    Electronic Resource
    Opiates Inhibit Acetylcholine Release from Torpedo Nerve Terminals by Blocking Ca2+ Influx (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 43 (1984), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: In the present communication we report that Ca2+-dependent acetylcholine release from K+-depolarized Torpedo electric organ synaptosomes is inhibited by morphine, and that this effect is blocked by the opiate antagonist naloxone. This finding suggests that the purely cholinergic Torpedo electric organ neurons contain pre-synaptic opiate receptors whose activation inhibits acetylcholine release. The mechanisms underlying this opiate inhibition were investigated by comparing the effects of morphine on acetylcholine release induced by K+ depolarization and by the Ca2+ ionophore A23187 and by examining the effect of morphine on 45Ca2+ influx into Torpedo nerve terminals. These experiments revealed that morphine inhibits 45Ca2+ influx into K+-depolarized Torpedo synaptosomes and that this effect is blocked by naloxone. The effects of morphine on K+ depolarization-mediated 45Ca2+ influx and on acetylcholine release have similar dose dependencies (half-maximal inhibition at 0.5–1 μM), suggesting that opiate inhibition of release is due to blockage of the presynaptic voltage-dependent Ca2+ channel. This conclusion is supported by the finding that morphine does not inhibit acetylcholine release when the Ca2+ channel is bypassed by introducing Ca2+ into the Torpedo nerve terminals via the Ca2+ ionophore.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1984.tb12779.x
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  • 3
    Electronic Resource
    Electronic Resource
    ATP-Stimulated Ca2+ Transport into Cholinergic Torpedo Synaptic Vesicles (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 35 (1980), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Activation of the Ca2+/Mg2+ ATPase associated with highly purified Torpedo synaptic vesicles results in 45Ca2+ uptake. The accumulated 45Ca2+ is released by hypoosmotic buffer and by the Ca2+ ionophore A23187. Density-gradient centrifugation and permeation chromatography reveal that vesicular acetylcholine and the membrane-bound 45Ca2+ co-migrate, thus implying that 45Ca2+ is transported into cholinergic vesicles. ATP-dependent 45Ca2+ uptake follows saturation kinetics, with KmCa2+= 50 μM, KmATP= 5 μM, and Vmax= 3 ± 0.3 nmol Ca2+/mg protein/min. Treatment of the vesicles with mersalyl, dicyclohexyl-carbodiimide, and quercetin leads to inactivation of the Ca2+/Mg2+ ATPase and to comparable inhibition of 45Ca2+ transport. Ruthenium red and ouabain have no effect on either of these activities. Nigericin in the presence of external K+ is a potent inhibitor of 45Ca2+ translocation, whereas gramicidin activates transport. The proton translocator carbonylcyanide p-trifluoromethoxy-phenylhydrazone (FCCP) and FCCP + the ionophore valinomycin partially inhibit 45Ca2+ transport. By contrast, the above ionophores do not affect Ca2+/Mg2+ ATPase activity. Tentative mechanisms for ATP-dependent Ca2+ transport into cholinergic synaptic vesicles and the physiological significance of this process are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1980.tb12496.x
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  • 4
    Electronic Resource
    Electronic Resource
    INDUCED ACETYLCHOLINE RELEASE FROM ACTIVE PURELY CHOLINERGIC TORPEDO SYNAPTOSOMES (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 30 (1978), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Viablse, purely cholinergic synaptosomes were prepared from the electric organ of Torpedo ocellata and partially purified by differential and sucrose density centrifugation. The synaptosomes contain acetylcholine (ACh), synaptic vesicles, cytoplasmic markers and mitochondria. No adherent postsynaptic membranes were detected. K+ depolarization as well as the ionophore A23187 mediate Ca2+ permeation into the synaptosomes and the consequent release of ACh. Mg2+ does not evoke ACh release whereas Sr2+ and Ba2+ can replace Ca2+ in evoking K+ depolarization induced ACh secretion. In accordance with the calcium hypothesis of stimulus–secretion coupling, both K+ depolarization and the ionophore A23187 seem to mediate the release of the same population of ACh molecules. The mode of action of the ionophore X537A differs from that of A23187. X537A acts independently of Ca2+ and induces the release of a larger fraction of the ACh contained in the fractionated nerve terminals. These results demonstrate that the Torpedo synaptosomes contain the neurosecretion apparatus in a functional active state. This preparation extends the utility of synaptosomes for structural and functional biochemical studies of neurotransmission, as it uniquely contains only one neurosecretion system (cholinergic).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1978.tb07055.x
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  • 5
    Electronic Resource
    Electronic Resource
    M1 Muscarinic Agonist Treatment Reverses Cognitive and Cholinergic Impairments of Apolipoprotein E-Deficient Mice (1998)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 70 (1998), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Recent studies suggest that apolipoprotein E (apoE) plays a specific role in brain cholinergic function and that the E4 allele of apoE (apoE4), a major risk factor for Alzheimer's disease (AD), may predict the extent of cholinergic dysfunction and the efficacy of cholinergic therapy in this disease. Animal model studies relevant to this hypothesis revealed that apoE-deficient (knockout) mice have working memory impairments that are associated with distinct dysfunction of basal forebrain cholinergic neurons. Cholinergic replacement therapy utilizing M1-selective muscarinic agonists has been proposed as effective treatment for AD patients. In the present study, we examined whether the memory deficits and brain cholinergic deficiency of apoE-deficient mice can be ameliorated by the M1-selective agonist 1-methylpiperidine-4-spiro-(2′-methylthiazoline), [AF150(S)]. Treatment of apoE-deficient mice with AF150(S) for 3 weeks completely abolished their working memory impairments. Furthermore, this reversal of cognitive deficit was associated with a parallel increase of histochemically determined brain choline acetyltransferase and acetylcholinesterase levels and with the recovery of these cholinergic markers back to control levels. These findings show that apoE deficiency-related cognitive and cholinergic deficits can be ameliorated by M1-selective muscarinic treatment. They also provide a novel model system for development and evaluation of therapeutic strategies directed specifically at the AD patients whose condition is attributed to the apoE genotype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1998.70051991.x
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  • 6
    Electronic Resource
    Electronic Resource
    Site-Specific Dephosphorylation of Tau of Apolipoprotein E-Deficient and Control Mice by M1 Muscarinic Agonist Treatment (1999)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 72 (1999), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : Apolipoprotein E (apoE)-deficient mice have memory deficits that are associated with synaptic loss of basal forebrain cholinergic projections and with hyperphosphorylation of distinct epitopes of the microtubuleassociated protein tau. Furthermore, treatment of apoEdeficient mice with the M1 selective agonist 1-methylpiperidine-4-spiro-(2'-methylthiazoline) [AF 150(S)] abolishes their memory deficits and results in recovery of their brain cholinergic markers. In the present study, we used a panel of anti-tau monoclonal antibodies to further map the tau epitopes that are hyperphosphorylated in apoE-deficient mice and examined the effects of prolonged treatment with AF 150(S). This revealed that tau of apoE-deficient mice contains a distinct, hyperphosphorylated “hot spot” domain which is localized N-terminally to the microtubule binding domain of tau, and that AF150(S) has an epitope-specific tau dephosphorylating effect whose magnitude is affected by apoE deficiency. Accordingly, epitopes which reside in the hyperphosphorylated “hot spot” are dephosphorylated by AF 150(S) in apoE-deficient mice but are almost unaffected in the controls, whereas epitopes which flank this tau domain are dephosphorylated by AF150(S) in both mice groups. In contrast, epitopes located at the N and C terminals of tau are unaffected by AF150(S) in both groups of mice. These findings suggest that apoE deficiency results in hyperphosphorylation of a distinct tau domain whose excess phosphorylation can be reduced by muscarinic treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1999.0720206.x
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  • 7
    Electronic Resource
    Electronic Resource
    MAGNETIC RESONANCE STUDIES OF MEMBRANE AND MODEL MEMBRANE SYSTEMS. V. COMPARISONS OF AQUEOUS DISPERSIONS OF PURE AND MIXED PHOSPHOLIPIDS (1973)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 222 (1973), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1973.tb15281.x
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  • 8
    Electronic Resource
    Electronic Resource
    Observations on feeding, growth and electric discharge of newborn Torpedo ocellata (chondrichthyes, batoidei) (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 15 (1979), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Newly born and neonate Torpedo ocellata were obtained from gravid females caught during the autumn off the Mediterranean coast of Israel. The young torpedos, which weighed about 11 g, were fed with live Blennius pavo Risso, and doubled their weight in about 4 months. The behaviour of the torpedo during feeding was examined and photographed. When attacking a fish, the torpedo emerges from being buried in the sand and assaults the approaching prey. First, the prey is trapped under the torpedo and then directed towards the ray's mouth by its body movements. Newborn and neonate torpedos are able to discharge their electric organ. The amplitude of the discharge of one day-old fish is approximately 4 V. It increases dramatically during the first three weeks of life to 20 V, reaching an asymptotic level of about 26 V, by the end of the fourth month.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1979.tb03579.x
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  • 9
    Electronic Resource
    Electronic Resource
    Isolation and characterization of the highly phosphorylated repeat domain of distinct heavy neurofilament subunit (NF-H) isoforms (1996)
    Springer
    Cellular and molecular neurobiology 16 (1996), S. 463-477 
    Details
    ISSN: 1573-6830
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Recent examination of the hypothesis that distinctly phosphorylated NF-H isoforms exist in different types of neurons revealed that the extent of phosphorylation of the heavy neurofilament polypeptide of bovine ventral root motor neurons is markedly higher than that of dorsal root neurons. 2. In the present study we employed endoproteinase ASP-N for isolating the Lys-Ser-Pro (KSP)-rich domain of NF-H, which contains most of the NF-H phosphorylation sites. 3. Treatment of NF-H with ASP-N endoproteinase results in a cascade of products, the last of which is a polypeptide with apparent molecular weight of 120 kDa. Amino terminal sequence and amino acid composition analysis revealed that this fragment contains the KSP-rich domain of NF-H. 4. Treatment of ventral and dorsal root NF-H with ASP-N endoproteinase and analysis of the phosphoserine contents of the resulting 120 kDa fragments revealed that the 120 kDa fragment of ventral root NF-H is significantly more phosphorylated than that of dorsal root NF-H.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02150227
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  • 10
    Electronic Resource
    Electronic Resource
    Reconstitution of a purified acetylcholine receptor (1976)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 4 (1976), S. 419-426 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Dialysis of the purified acetylcholine receptor from Torpedo californica electroplax with lipids from the same organ results in a vesicular membrane system in which the receptor is embedded in the bilayer and oriented so that most of the neurotoxin-binding sites appear to be on the outer surface. The constituted vesicles are chemically excitable by acetylcholine and carbamylcholine, as measured by 22Na+ efflux. The excitability is specifically blocked by the antagonist α-bungarotoxin. These results demonstrate that the purified reconstituted receptor system not only can specifically bind neurotransmitter but also can trigger ion translocation. It therefore has the properties necessary to effect postsynaptic depolarization in vivo.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400040312
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