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  • 1
    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: There is mounting evidence that at least some of the neurotoxicity associated with Alzheimer's disease (AD) is due to proteolytic fragments of the β-amyloid precursor protein (βAPP). Most research has focused on the amyloid β protein (Aβ), which has been shown to possess ion channel activity. However, the possible role of other cleaved products of the βAPP is less clear. We have investigated the ability of various products of βAPP to induce membrane ion currents by applying them to Xenopus oocytes, a model system used extensively for investigating electrophysiological aspects of cellular, including neuronal, signalling. We focussed on the 105-amino-acid C-terminal fragment (CT105) (containing the full sequence Aβ), which has previously been found to be toxic to cells, although little is known about its mode of action. We have found that CT105 is exceedingly potent, with a threshold concentration of 100–200 nM, in inducing nonselective ion currents when applied from either outside or inside the oocyte and is more effective than either βAPP or the Aβ fragments, β25–35 or β1–40. The ion channel activity of CT105 was concentration dependent and blocked by a monoclonal antibody to Aβ. These results suggest the possible involvement of CT105 in inducing the neural toxicity characteristic of AD.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Expression of the carboxyl-terminal fragment (CT) of the β-amyloid precursor protein (APP) in transgenic animals has been linked with neurotoxicity. However, it remains to be clarified whether the neurotoxicity is caused by β-amyloid proteins (Aβs) derived from CT or by CT itself. To study the in vivo neurotoxicity of CT, mice were given a single intracerebroventricular injection of a recombinant 105-amino acid CT (CT105; 68.5–685 pmol, intracerebroventricularly), and changes in behavior and in brain histology were examined. Animals given CT105 (410 or 685 pmol, intracerebroventricularly) showed a dose-dependent impairment in the passive avoidance performance, whereas boiled CT105 had no effect. CT105 (685 pmol, intracerebroventricularly) induced reactive gliosis in neocortex and hippocampus and neurodegeneration in neocortex. These results indicate that centrally administered CT105 induces behavioral impairment and neuropathologic changes, suggesting a direct toxic effect of CT105 per se.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 74 (2000), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The effects of peptide fragments of the β-amyloid precursor protein (βAPP) on parallel fiber (PF)-Purkinje cell synaptic transmission in the rat cerebellum were examined. Transient inward currents associated with calcium influx were induced by localized applications of the 105-amino acid carboxy-terminal fragment (CT105) of βAPP to discrete dendritic regions of intact Purkinje cells. βAPP and the amyloid β (Aβ) peptide fragments Aβ1-16, Aβ25-35, and Aβ1-42 had little or no effect. Inward currents were also observed following applications of CT105 to isolated patches of somatic Purkinje cell membrane. All five proteins/peptides induced some depression of α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor-mediated synaptic transmission between PFs and Purkinje cells, through a combination of pre- and postsynaptic effects. CT105 induced the greatest depression, which spread to distant synapses following local application and which was prevented by inhibition of nitric oxide synthase. These data indicate that CT fragments of the βAPP can modulate AMPA-mediated glutamatergic synaptic transmission in the cerebellar cortex. These fragments may therefore be considered alternative candidates for some of the neurotoxic effects of Alzheimer's disease.
    Type of Medium: Electronic Resource
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