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  • 1
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Conclusion This finding suggests that a descending histaminergic pathway is interrupted by lesions of this type. This descending system would be responsible for the high density of terminals projecting in restricted areas of the brainstem.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Conclusion Since lesions placed more caudally failed to produce degeneration of terminals in the telencephalon, this suggests that histaminergic cell bodies are present in the upper mesencephalon or posterior hypothalamus.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Inflammation research 3 (1973), S. 190-191 
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1424
    Keywords: catecholamine secretion ; medullary chromaffin cell ; perussis toxin ; G-type Ca2+ channel ; L-type Ca2+ channel ; G-protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary We have previously shown that pertussis toxin (PTX) stimulates delayed-onset, [Ca2−] a -dependent catecholamine (CA) release from bovine chromaffin cells. We now show that this effect of PTX is inhibited in part (50%) by dihydropyridine Ca2−-channel antagonists niludipine and nifedipine, and is potentiated by the dihydropyridine Ca2+-channel agonist Bay K-8644. We and others have shown that pretreatment of chromaffin cells with PTX results in enhanced catecholamine secretion in response to high [K−] a , nicotine and muscarine, and here we extend these observations by showing that toxin pretreatment also enhances the secretory response to [Ba2+] a . All these data are consistent with the concept that PTX may act on Ca2− channels. To examine the possibility of a direct action of the toxin on the voltage-gated L-type Ca2+ channel known to be present in these cells, we studied the effects of the toxin on whole cell Ca2+ currents. We found and report here that spontaneous electrical activity was considerably increased in PTX-treated cells. Our measurements of whole cell inward Ca2+ currents indicate that the underlying mechanism is a marked shift of the activation curve of the L-type Ca2+ current along the voltage axis towards more negative potentials. While treatment of the cells with PTX had no effect on L-type Ca2+-channel conductance (6 nS/cell at 2.6mm [Ca2+] a ). PTX evoked the activation of a new class of Ca2+-selective channels (5 pS in 25mm [Ca2+]pipet), which are rather insensitive to membrane potential. We have termed theseG-type calcium channels. These data suggest that treatment with PTX not only increases the probability of L-type Ca2+-channel activation at more negative potentials, but also increases the probability of opening of an entirely new, voltage-independent, Ca2+ channel. These actions of PTX should promote Ca2+ entry and might explain the stimulation by the toxin of CA secretion from medullary chromaffin cells in culture.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 635 (1991), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 184 (1959), S. 1400-1400 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Studies with Evans blue have shown, however, that this could be accounted for by the amount of supernatant trapped in the loosely packed sediment. The leakage of enzyme could not be inhibited either by increasing the concentration of glucose to 500 mgm. per cent and using a medium containing ...
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 125I-Aminopotentidine (125I-APT), a reversible probe of high specific radioactivity and high affinity and selectivity for the H2 receptor, was used to characterize and localize this histamine receptor subtype in human brain samples obtained at autopsy. On membranes of human caudate nucleus, specific 125I-APT binding at equilibrium revealed a single component, with a dissociation constant of 0.3 nM and maximal capacity of about 100 fmol/mg of protein. At 0.2 nM, 125I-APT specific binding, as defined with tiotidine, an H2-receptor antagonist chemically unrelated to iodoaminopotentidine, represented 40–50% of the total. Specific 125I-APT binding was inhibited by a series of typical H2-receptor antagonists that displayed apparent dissociation constants closely similar to corresponding values at the reference biological system, i.e., guinea pig atrium. This indicates that the pharmacology of the H2 receptor is the same in the human brain as on this reference system. However, histamine was about 10-fold more potent in inhibiting 125I-APT binding to membranes of human brain than of guinea pig brain. 125I-APT binding was also inhibited by amitriptyline and mianserin, two antidepressant drugs, in micromolar concentrations corresponding to effective plasma concentrations of treated patients. The distribution of H2 receptors was established autoradiographically with 125I-APT on a series of coronal sections of human brain after assessing the pharmacological specificity of the labeling. The highest density of 125I-APT sites was found in the basal ganglia, various parts of the limbic system, e.g., hippocampus or amygdaloid complex, and the cerebral cortex. H2 receptors displayed a laminar distribution in cerebral cortex and hippocampal formation. A low density of sites was found in cerebellum as well as in hypothalamus, the brain area where all the perikarya and the largest number of axons of histaminergic neurons are found. The widespread distribution of H2 receptors in the human brain is consistent with the alleged modulatory role of histamine mediated by this subtype of receptor.
    Type of Medium: Electronic Resource
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  • 8
    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: Serum albumin conjugates of histamine or tele-methylhistamine, a major catabolite, were prepared using 1,4-benzoquinone as the coupling agent and used to raise polyclonal antibodies in rabbits. The same reagent was used to prepare the [125I]iodinated tracer and treat tissue extracts submitted to the radioimmunoassays. The IC50 values of prederivatized histamine and tele-methylhistamine in the radioimmunoassays were 0.3 nM and 0.5 nM, respectively, whereas nonderivatized histamine or tele-methylhistamine, histidine, a variety of histamine derivatives, amines, etc., had at least 1,000-fold higher IC50 values. Application of the radioimmunoassays to nonpurified extracts of rat brain allowed the quantification of the two amine immunoreactivities in samples corresponding to less than 1 mg of hypothalamus. The tissue immunoreactivity corresponded to authentic histamine or tele-methylhistamine, as shown by (a) the parallel 125I-tracer displacement curves, (b) the similar elution patterns from HPLC columns, (c) the regional levels of histamine and tele-methylhistamine in brain, similar to those obtained with other methods, and (d) the clearcut effects of treatments with inhibitors of l-histidine decarboxylase or monoamine oxidase. The two radioimmunoassays appear as simple and sensitive tools to evaluate steady-state levels and turnover rates of histamine and tele-methylhistamine
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: We have studied whether the delayed cell death induced by transient forebrain ischemia is associated with an inter-nucleosomal cleavage of DNA into oligonucleosome-sized fragments. The integrity of genomic DNA in various brain regions after a 20-min four-vessel ischemia was examined using gel elec-trophoresis. We found typical ladders of oligonucleosomal DNA fragments in the striatum and in the Ammon's horn. In the latter we also often found a random DNA degradation as a smear pattern. These findings were reinforced by a specific in situ labeling of DNA breaks in tissue sections. A dark staining of nuclei was observed in the cell bodies of neurons—in particular in the head of the caudate and in the vulnerable CAl hippocampal area. With biochemical and histological approaches, there was no evidence of DNA degradation in regions that are resistant to the injury. We conclude that the association of multiple mechanisms of cell damage may occur after a global ischemia. The regional variability in DNA fragmentation stresses the importance of using histological approaches in parallel with gel electrophoresis.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Medicine 9 (1958), S. 47-68 
    ISSN: 0066-4219
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine
    Type of Medium: Electronic Resource
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