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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Accumulating evidence supports the hypothesis that brain iron misregulation and oxidative stress (OS), resulting in reactive oxygen species (ROS) generation from H2O2 and inflammatory processes, trigger a cascade of events leading to apoptotic/necrotic cell death in neurodegenerative disorders, such as Parkinson's (PD), Alzheimer's (AD) and Huntington's diseases, and amyotrophic lateral sclerosis (ALS). Thus, novel therapeutic approaches aimed at neutralization of OS-induced neurotoxicity, support the application of ROS scavengers, transition metals (e.g. iron and copper) chelators and non-vitamin natural antioxidant polyphenols, in monotherapy, or as part of antioxidant cocktail formulation for these diseases. Both experimental and epidemiological evidence demonstrate that flavonoid polyphenols, particularly from green tea and blueberries, improve age-related cognitive decline and are neuroprotective in models of PD, AD and cerebral ischemia/reperfusion injuries. However, recent studies indicate that the radical scavenger property of green tea polyphenols is unlikely to be the sole explanation for their neuroprotective capacity and in fact, a wide spectrum of cellular signaling events may well account for their biological actions. In this article, the currently established mechanisms involved in the beneficial health action and emerging studies concerning the putative novel molecular neuroprotective activity of green tea and its major polyphenol (-)-epigallocatechin-3-gallate (EGCG), will be reviewed and discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In the present study we demonstrate neuroprotective property of green tea extract and (–)-epigallocatechin-3-gallate in N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mice model of Parkinson's disease. N-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine neurotoxin caused dopamine neuron loss in substantia nigra concomitant with a depletion in striatal dopamine and tyrosine hydroxylase protein levels. Pretreatment of mice with either green tea extract (0.5 and 1 mg/kg) or (–)-epigallocatechin-3-gallate (2 and 10 mg/kg) prevented these effects. In addition, the neurotoxin caused an elevation in striatal antioxidant enzymes superoxide dismutase (240%) and catalase (165%) activities, both effects being prevented by (–)-epigallocatechin-3-gallate. (–)-Epigallocatechin-3-gallate itself also increased the activities of both enzymes in the brain. The neuroprotective effects are not likely to be caused by inhibition of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine conversion to its active metabolite 1-methyl-4-phenylpyridinium by monoamine oxidase-B, as both green tea and (–)-epigallocatechin-3-gallate are very poor inhibitors of this enzyme in vitro (770 µg/mL and 660 µM, respectively). Brain penetrating property of polyphenols, as well as their antioxidant and iron-chelating properties may make such compounds an important class of drugs to be developed for treatment of neurodegenerative diseases where oxidative stress has been implicated.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To establish the possible roles of oxidative stress, inflammatory processes and other unknown mechanisms in neurodegeneration, we investigated brain gene alterations in N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mice model of Parkinson's disease using Atlas mouse cDNA expression array membrane. The expression of 51 different genes involved in oxidative stress, inflammation, glutamate and neurotrophic factors pathways as well as in still undefined processes, such as cell cycle regulators and signal transduction molecules, was differentially affected by the treatment. The present study indicates the involvement of an additional cascade of events that might act in parallel to oxidative stress and inflammation to converge eventually into a common pathway leading to neurodegeneration. The attenuation of these gene changes by R-apomorphine, an iron chelator-radical scavenger drug, supports our previous findings in vivo where R-apomorphine was neuroprotective.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 77 (2001), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In order to establish whether the antioxidant and iron-chelating activities of R-apomorphine (R-APO), a D1-D2 receptor agonist, may contribute to its neuroprotective property, its S-isomer, which is not a dopamine agonist, was studied. The neuroprotective property of R- and S-APO has been studied in the MPTP model of Parkinson's disease (PD). Both S-APO (0.5–1 mg/kg, subcutaneous) and R-APO (10 mg/kg) pretreatment of C57-BL mice, protected against MPTP (24 mg/kg, intraperitoneally) induced dopamine (DA) depletion and reduction in tyrosine hydroxylase (TH) activity. However, only R-APO prevented nigro-striatal neuronal cell degeneration, as indicated by the immunohistochemistry of TH positive neurones in substantia nigra and by western analysis of striatal TH content. R-APO prevented the reduction of striatal-GSH and the increase in the ratio of GSSG over total glutathione, caused by MPTP treatment. In vitro both R-APO and S-APO inhibited monoamine oxidase A and B activity at relatively high concentrations (100 and 300 µmol/L, respectively). The elevated activity of TH induced by the two enantiomers may contribute to the maintenance of normal DA levels, suggesting that one of the targets of these molecules may involve upregulation of TH activity. It is suggested that the antioxidant and iron-chelating properties, possible monoamine oxidase inhibitory actions, together with activation of DA receptors, may participate in the mechanism of neuroprotection by APO enantiomers against MPTP.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 15 (1994), S. 139-147 
    ISSN: 0192-253X
    Keywords: IME1 ; meiosis ; transcriptional activator ; S. cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Previous studies have shown that the IME1 gene is required for sporulation and the expression of meiosis specific genes in Saccharomyces cerevisiae. However, sequence analysis has not revealed the precise functional role of the Ime1 protein. By engineering constructs which express various portions of the Ime1p fused to either the DNA binding or transcriptional activation domains of GAL4, we have conclusively demonstrated that IME1 is a transcription factor, apparently required for sporulation to activate the transcription of meiosis specific genes. The full Ime1p, when fused to the GAL4 DNA binding domain, can both activate GAL1-IacZ expression, and complement Ime1-0 (a null allele) for the ability to sporulate, and transcriptionally activate IME2, a meiosis specific gene. As successively larger portions of the encoded Ime1p N-terminus are deleted from the GAL4(bd)-IME1 construct, the encoded fusion proteins retain the ability to complement an ime1 null allele, despite a decreasing ability to activate GAL1-lacZ transcription. However, a fusion construct which retains only the last 45 C-terminal amino acids of IME1 provides neither transcriptional activation of GAL1-lacZ nor complementation of ime1-0. Fusion of a GAL4 activation domain to this portion of IME1, results in a construct with a restored ability to complement an ime1-0 cllele. This restored ability is dependent upon galactose induction. We conclude, therefore, that IME1 functions in meiosis as a transcriptional activator. © 1994 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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