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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 52 (1989), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Polyunsaturated fatty acid (PUFA) levels (an index of the amount of substrate available for lipid peroxidation) were measured in several brain regions from patients who died with Parkinson's disease and age-matched control human postmortem brains. PUFA levels were reduced in parkinsonian substantia nigra compared to other brain regions and to control tissue. However, basal malondialdehyde (MDA; an intermediate in the lipid peroxidation process) levels were increased in parkinsonian nigra compared with other parkinsonian brain regions and control tissue. Expressing basal MDA levels in terms of PUFA content, the difference between parkinsonian and control substantia nigra was even more pronounced. Stimulating MDA production by incubating tissue with FeSO4 plus ascorbic acid, FeSO4 plus H2O2, or air alone produced lower MDA levels in the parkinsonian substantia nigra, probably reflecting the lower PUFA content. These results may indicate that an increased level of lipid peroxidation continues to occur in the parkinsonian nigra up to the time of death, perhaps because of continued exposure to excess free radicals derived from some endogenous or exogenous neurotoxic species.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Iron is abnormally accumulated in the substantia nigra pars compacta of patients with Parkinson's disease (PD). Because neuronal and glial iron uptake seems to be mediated by the binding of ferrotransferrin to a specific high-affinity receptor on the cell surface, the number of transferrin receptors could be altered in this disease. The regional distribution of specific binding sites for human 125I-diferric transferrin has been studied in the mesencephalon, on cryostat-cut sections from autopsy brains of control subjects and parkinsonian patients by in vitro autoradiography. Densities of binding sites were highest in the central gray substance (˜10 fmol/mg of tissue equivalent), intermediate in the catecholaminergic cell group A8, superior colliculus, and ventral tegmental area, and almost nonexistent in the substantia nigra. The density of 125I-transferrin binding sites was not significantly different between parkinsonian and control brains in any region analyzed. These results show that in the mesencephalon the regional density of transferrin binding sites is lowest in the dopaminergic cell groups, which are the most vulnerable to PD, and suggest that iron does not accumulate through an increased density of transferrin receptors at the level of the substantia nigra.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Parkinson's disease is characterized by massive degeneration of the melanized dopaminergic neurons in the substantia nigra. The functional capacity of the surviving nigral neurons is affected, as indicated by the subnormal levels of tyrosine hydroxylase (TH) mRNA in these neurons and the presence in the parkinsonian mesencephalon of melanized neurons lacking TH immunoreactivity. This is apparently in contradiction with the known overactivity of dopamine synthesis and release that occurs in the remaining dopaminergic terminals. To test the ability of the surviving neurons to express TH protein, a semiquantitative immunocytochemical method was developed. The relative amounts of TH were estimated with a computer-assisted image analysis system in the dopaminergic neurons of representative mesencephalic sections of control and parkinsonian brains and for comparison in brains from patients with Alzheimer's disease. In control brains, the mean TH content per neuron differed from one subject to another and between the different dopaminergic cell groups of the mesencephalon in the same subject. Within a given dopaminergic region, the level of TH was variable among neurons. In patients with Parkinson's disease, the ratio of TH protein content per neuron in the substantia nigra by reference to that of the central gray substance was reduced. In patients with Alzheimer's disease, the amount of TH was selectively reduced in the remaining dopaminergic neurons of the ventral tegmental area, a region characterized by a loss in dopaminergic neurons. The decrease in cellular TH content might therefore be related to the presence of the neurodegenerative process in the area considered. In patients with Parkinson's disease, the incapacity of the surviving neurons to express normal TH levels may reduce the efficiency of the hyperactivity mechanisms that develop in the remaining striatal dopaminergic terminals.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The contribution of neuromelanin (NM) to the pathogenesis of Parkinson's disease (PD) has long been suspected. In particular, a correlation has been reported between the estimated cell loss in the mesencephalic dopaminergic cell groups and the percentage of NM-pigmented neurons in these cell groups. To test whether the amount of pigment per cell is a critical factor or whether the presence of NM within a neuron is sufficient to account for the degeneration of dopaminergic neurons, the NM content was measured in each neuron from representative sections throughout the ventral mesencephalon of four control subjects and four patients with PD. Intraneuronal NM was quantified by a densitometric method, using known amounts of synthetic melanin as standards. In control brains, the distribution of melanized neurons in the nigral complex showed a high proportion of lightly melanized neurons in the ventral tegmental area and the pars α and γ of the substantia nigra (SN), whereas heavily melanized neurons were mostly located in the pars β and lateralis of the SN. An inverse relationship was observed between the percentage of surviving neurons in PD compared with controls and the amount of NM they contain, suggesting that the vulnerability of the dopaminergic neurons is related to their NM content. Factors other than NM may be involved in the differential vulnerability of catecholaminergic neurons in PD. In particular, the constant topography of the cell loss suggests that cell position within the nigral complex is a key factor.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 56 (1991), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The levels of different elements were studied by x-ray microanalysis in the substantia nigra and the central gray substance of patients with Parkinson's disease, progressive supranuclear palsy, and matched controls. In control brains, only iron, potassium, silicium, sodium, sulfur, and zinc were within the limit of detection of the technique. The abundance of each element was different, but their respective concentrations in the two brain regions were similar, except for sulfur levels which were higher on neuromelanin aggregates in the substantia nigra than in nigral regions lacking neuromelanin, and in the central gray substance. In Parkinson's disease, but not in progressive supranuclear palsy, nigral iron levels increased in regions devoid of neuromelanin and decreased on neuromelanin aggregates, but were unchanged in the central gray substance, when compared to control values. Concentrations of the other elements in the central gray substance and substantia nigra were not different from controls in brains from patients with Parkinson's disease and progressive supranuclear palsy. Analysis of Lewy bodies in the parkinsonian substantia nigra revealed high levels of iron and the presence of aluminum. Metal abundance was not affected in progressive supranuclear palsy, in spite of the nigral cell death. This suggests that the increased iron levels and the detection of aluminum observed in Parkinson's disease are not solely the consequence of the neuronal degeneration.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 60 (1993), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract Treatment of common marmosets with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP; 1–4mg/kgfor up to 4 days) caused a profound parkinsonian state. Ten days from the start of MPTP treatment, all animals showed marked motor impairment, consisting of bradykinesia and akinesia, limb rigidity, postural abnormalities, loss of vocalisation and blink reflex, and, on occasions, postural tremor. Measurement of caudate-putamen monoamine content at this time showed a profound loss in 3,4-dihydroxyphenyl-ethylamine, homovanillic acid, and 3,4-dihydroxyphenylacetic acid concentrations. Measurement of neuropeptide concentrations in the caudate-putamen, internal and external segments of the globus pallidus, nucleus accumbens, substantia nigra, frontal cortex, and hippocampus showed met-enkephalin, leu-enkephalin, and cholecystokinin (CCK-8) concentrations to be unaffected by MPTP treatment. There was a small decrease in the substance P content of frontal cortex, but otherwise the content of this neuropeptide was unaltered. Parkinsonism in the marmoset, induced by MPTP treatment 10 days earlier, does not alter neuropeptide concentrations in the manner observed in Parkinson's disease.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Tyrosine hydroxylase (TH), glutamic acid decarboxylase (GAD), and choline acetyl transferase (CAT) were used as markers for catecholamine, γ-aminobutyric acid, and acetylcholine containing neurons in human mesencephalon. Their rostrocaudal, mediolateral, and dorsoventral distribution was investigated within the substantia nigra pars compacta (SNC) and pars reticulata (SNR) and in the ventral tegmental area (VTA). TH activity was highest in the caudal, medial, and ventral SNC and in the middle of VTA medioventrally. The enzyme activity in SNR was low and uniformly distributed. In SNC as well as SNR, GAD activity was high and greater laterally and in the middle of the rostro-caudal extent. No particular pattern of distribution was observed in VTA, an area with low GAD content. In the substantia nigra, CAT activity was low. A characteristic medio-ventral distribution with a peak of high enzyme activity in the middle of the rostrocaudal extent was observed. In VTA, enzyme levels were high and also concentrated medio-ventrally and in the middle of the area. In parkinsonian brains, the distribution of TH was uniformly affected throughout the rostro-caudal extent. In VTA the enzyme activity was not as reduced as in SNC and SNR; the CAT pattern was only disrupted in a very localized part of SNC but not in SNR and VTA. In all three areas, GAD activity was reduced to a uniformly low distribution.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 37 (1981), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: [3H]Imipramine binds with high affinity to membranes from different regions of the human brain. The highest density of binding sites was observed in the hypothalamus and substantia nigra and the lowest density in the white matter and cerebellum. As found in rat brain, tricyclic antidepressant drugs are potent inhibitors of [3H]imipramine binding. Atypical antidepressants are, however, much weaker at inhibiting the specific binding. The [3H]imipramine binding site in human cortex is apparently identical to the site already described in the rat brain and in human platelets.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The high levels of dopamine (DA) detected in the ventral tegmental area (VTA), as well as in the substantia nigra (SN) of human brain, suggest the presence of DA cells in these areas. This favors the possible existence of a mesocortico-limbic system besides the mesostriatal pathway. In Parkinson's disease both DA systems seem to be deficient.
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