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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Analytical Biochemistry 121 (1982), S. 378-381 
    ISSN: 0003-2697
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 263 (1976), S. 341-343 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In male rats (200300 g) of a random-bred SIV (SpragueDawleyIvanovas) strain, the somatodendritic complex was analysed as a whole with biochemical techniques, while DA nerve cell bodies were studied by histo-chemical microfluorimetry13. For biochemical analyses the brains were quickly removed after ...
    Type of Medium: Electronic Resource
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  • 3
    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: Cultures of dissociated embryonic rat mesencephalic cells were exposed to 10 μM 1-methyl-4-phenylpyridinium (MPP+), a concentration shown earlier to result in loss of 〉85% of tyrosine hydroxylase (TH)-positive neurons without affecting the total number of cells observed by phase-contrast microscopy. To characterize better the selectivity of the toxic action of MPP+, other parameters were measured reflecting survival and function of dopaminergic or nondopaminergic neurons. Exposure of cultures to 10 μM MPP+ for 48 h reduced TH activity to 11% of control values without reducing protein levels. [3H]Dopamine uptake was reduced to 〈 4% of control values, whereas the uptake of γ-[3H]aminobutyric acid ([3H]GABA) was not affected in these cultures. This same treatment failed to reduce the number of cholinergic cells visualized in septal cultures and did not affect either choline acetyltransferase activity or high-affinity choline uptake. To assess for possible recovery of dopaminergic neurons, cultures were exposed to 10, 1.0, or 0.1 μM MPP+ for 48 h and then kept for up to 6 days in MPP+-free medium. After exposure to 10 μM MPP+, the number of TH-positive neurons, their neurite density, TH activity, and [3H]dopamine uptake remained at constant, reduced levels throughout the period of observation after termination of exposure, whereas GABA uptake remained normal. Treatment with lower concentrations of MPP+, i.e., 1.0 and 0.1 μM, induced less pronounced dopaminergic toxic effects. However, no recovery was seen after posttreatment incubation in toxin-free medium. These findings provide evidence that MPP+ treatment results in highly selective and irreversible toxicity for cultured dopaminergic neurons.
    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: The neurotoxic metabolite of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1 -methyl-4-phenylpyr-idinium, selectively accumulates in dopaminergic neurons via the dopamine reuptake system. Consequently, nontoxic radiolabeled MPTP analogs may be potentially useful for visualizing catecholaminergic neurons in vivo. N-Methyl-4-(4 - hydroxy - 3 - [l25I]iodobenzyl) -1,2,3,6 - tetrahydropyridine ([l25I]MHTP), an analog of the nontoxic N-methyl-4-benzyl-1,2,3,6-tetrahydropyridine, has been studied in rats and mice. After intravenous administration of [125I]MHTP to rodents, the initial accumulation of radioactivity within the brain was found to be comparable to that of radiolabeled MPTP. Following intravenous administration of [125I]MHTP, in vivo autoradiographic visualization of the rodent brain revealed selective accumulation of [I25I]MHTP-derived radioactivity within the locus ceruleus; there was no accumulation of the radiotracer within dopaminergic fibers and cell bodies. The accumulation of radioactivity within the locus ceruleus was blocked by pretreatment with pargyline, a result suggesting that an MHTP metabolite formed by monoamine oxidase was responsible for the localization of the radiotracer within this structure. The anatomical distribution of the radiolabel demonstrates selective accumulation of this metabolite within noradrenergic cell bodies and those fibers making up the locus ceruleus. These findings further suggest that nontoxic metabolites of MPTP may become useful for in vivo labeling of selected populations of catecholaminergic neurons.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The subcellular distribution of dopamine (DA) in substantia nigra from individual male rats was studied with a fractionation procedure on microscale. After differential centrifugation the distribution of DA coincided with that of noradrenaline (NA) which can serve as a marker for synaptosomes in this area. The proportion of DA/NA concentrations was about 1–2 in most fractions. Sixty per cent of nigral DA was found in P2 (17,000 g). When P, was layered on a continuous density gradient, DA and NA peaked at the density of 1.0–1.2 M-sucrose. Since DA-containing particles covered a relatively broad range on this gradient, particles between 0.7 and 1.3 M-sucrose were collected with a discontinuous density gradient. Sixty per cent of DA from P2, was found in this subfraction.The particles containing DA could have been derived from dendrites or axon collaterals of nigrostriatal neurones or represent precursor DA in noradrenergic (NA) terminals. The role of collaterals was investigated by comparing the effect of γ-butyrolactone (GBL, 750 mg/kg, 1 h) on DA concentrations in subcellular fractions from substantia nigra and caudate-putamen. In caudate-putamen, GBL produced a marked increase of DA in total homogenates and subcellular fractions except P3, whereas DA concentrations remained unchanged in all fractions from substantia nigra. This speaks against a contribution from DA terminals.The proportion of DA contained as precursor in NA terminals was analysed after destruction of the NA input to substantia nigra by two methods. A single injection of 6-hydroxydopamine into the IV ventricle decreased nigral NA by 5574, DA only by 17%. Unilateral electrolytic lesions in the pontine tegmentum affected NA concentrations in homogenates and fraction P2 of the ipsilateral substantia nigra to a much greater extent than DA. From the results obtained with the two approaches, it is estimated that precursor DA in particulate fractions does not exceed 10%.Our observations indicate that dendrites of the DA neurones in substantia nigra can form particles which behave like synaptosomes on density gradients centrifugation; they may be termed ‘dendrosomes’. According to the proportion of DA found in the particulate fractions at least 4040% of nigral DA appear to be localised in dendrites.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 27 (1976), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of medicinal chemistry 23 (1980), S. 1438-1439 
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 2 (1990), S. 1-14 
    ISSN: 1435-1463
    Keywords: MPTP ; MPP+ ; neuromelanin ; Parkinson's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A relation between neuromelanin synthesis and vulnerability of dopaminergic neurons is suggested by the fact that heavily pigmented cells are preferentially lost in aging and Parkinson's disease and that the dopaminergic neurotoxin MPP+ (1-methyl-4-phenyl-pyridine) binds to neuromelanin. To elucidate the mechanism of neuromelanin synthesis, we studied the formation of melanin in homogenates of human and rat substantia nigra tissue “in vitro”. It was found that enzymatic processes accounted for 70% and 90% of the melanin formation in homogenates of human and rat tissue, respectively. The enzymatic synthesis was due to the activity of monoamine oxidase (MAO), since it was prevented by selective inhibitors of this enzyme. Both MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and MPP+ inhibited melanin formation, probably due to their ability to inhibit MAO. No evidence was found for involvement of cytochrome P-450 monooxigenases, which have been postulated to exist in central catecholaminergic neurons. Proadifen reduced melanin formation, not necessarily because it is an inhibitor of P-450 monooxigenases, but rather as it is also a potent inhibitor of MAO. Some antioxidants like ascorbic acid, but not agents destroying hydrogen peroxide, inhibited melanin formation. The findings suggest that the formation of neuromelanin in the substantia nigra involves MAO and non-enzymatic oxidative processes.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 49 (1980), S. 45-50 
    ISSN: 1435-1463
    Keywords: Tyrosine ; brain regions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Endogenous tyrosine concentrations varied two-fold among various rat brain regions, tending to be highest in brain stem structures. Administration of L-tyrosine (100 mg/kg) increased tyrosine concentrations in all brain areas; high relative increases were observed in areas with low initial tyrosine concentrations and vice versa, resulting in a more uniform distribution of tyrosine in the brain. Largest relative increases were observed in cortex and hippocampus. Tyrosine concentrations in all areas reached maximal levels 1 hour after tyrosine was given and declined gradually over the next 3 hours. The results suggest that tyrosine's effects on catecholamine synthesis and release might be amplified in cortex and hippocampus, where highest relative increases in tyrosine concentrations were observed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Der Orthopäde 28 (1999), S. 159-172 
    ISSN: 1433-0431
    Keywords: Key words Valgus foot • Flexible flatfoot • Rigid flatfoot • Tarsal coalition • Neuromuscular flatfoot ; Schlüsselwörter Knick-Senk-Fuß• Plattfuß• Talus verticalis • Kalkaneusosteotomie • Tarsale Koalition • Neurogener Knick-Platt-Fuß
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das fehlende oder ungenügend ausgebildete Fußlängsgewölbe ihrer Kinder bereitet den Eltern oft Sorgen. Eine echte Mißbildung in Form eines „Talus verticalis“ liegt in den seltensten Fällen vor. Bei den meisten Kindern ist das abgeflachte Fußgewölbe Teil der normalen Entwicklung und hat keinen Morbiditätswert. Der sog. Knick-Senk-Fuß ist deshalb auch nicht behandlungsbedürftig. Besteht im Fußabdruck bei einem über 3 Jahre alten Kind jedoch keine mediale Aussparung, so sprechen wir von einem Plattfuß. Ist er flexibel, so besteht Behandlungsbedürftigkeit vor allem dann, wenn die Belastung medial stärker ist als lateral. In Einzelfällen sind operative Maßnahmen, wie etwa eine Kalkaneusverlängerungsosteotomie sinnvoll. Ist der Plattfuß rigide, so liegt die Ursache meist in einer tarsalen Koalition. Die operative Durchtrennung der knöchernen Brücke mit Fettinterposition kann dieses Problem dauerhaft beheben. Plattfüße können auch neurogene Ursachen haben. Solche Füße können je nach Schweregrad mit Orthesen oder operativ behandelt werden, wobei bei schweren Fällen die Arthrodese im Rückfuß die besten Resultate bringt.
    Notes: Summary Many parents are anxious because of the insufficient arch of the feet of their children. A true congenital deformity (congenital vertical talus) is extremely rare. In children the arch is physiologically flattened with a hypervalgus of the hindfoot. Those feet do not need treatment. If there is no medial recess in the footprint in a child over 3 years of age, then we are talking about a flexible flatfoot. When the load of the foot is more pronounced at the medial rather than at the lateral side, operative treatment can be indicated, such as a lengthening osteotomy of the calcaneum. If the flatfoot is rigid, the reason for it is usually a tarsal coalition. Operative transection of the osseous bridge with fat interposition can solve the problem. Flatfeet may also occur in neuromuscular diseases. Depending on the severity of the deformity, splints can be effective, or – in the more severe cases – operative treatement such as a triple arthodesis can be indicated.
    Type of Medium: Electronic Resource
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