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  • 1
    Electronic Resource
    Electronic Resource
    Age-dependent changes in second messenger and rolipram receptor systems in the gerbil brain (1994)
    Springer
    Journal of neural transmission 97 (1994), S. 135-147 
    Details
    ISSN: 1435-1463
    Keywords: Aging ; second messenger ; rolipram ; gerbil ; phosphodiesterase ; receptor autoradiography ; neurotransmitter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Age-related alterations in binding sites of major second messengers and a selective adenosine 3′,5′-cyclic monophosphate (cyclic-AMP) phospho-diesterase (PDE) in the gerbil brain were analysed by receptor autoradiography. [3H]Phorbol 12,13-dibutyrate (PDBu), [3H]inositol 1,4,5-trisphosphate (IP3), [3H]forskolin, [3H]cyclic-AMP, and [3H]rolipram were used to label protein kinase C (PKC), IP3 receptor, adenylate cyclase, cyclic-AMP dependent protein kinase (PKA), and Ca2+/calmodulin-mdependent cyclic-AMP PDE, respectively. In middle-aged gerbils (16 months old), [3H]PDBu binding was significantly reduced in the hippocampal CA 1 sector, thalamus, substantia nigra, and cerebellum, compared with young animals (1 month old). [3H]IP3 binding revealed significant elevations in the nucleus accumbens, hippocampal CA 1 sector, dentate gyrus, and a significant reduction in cerebellum of middle-aged gerbils. [3H]Forskolin binding in middle-aged animals was significantly increased in the nucleus accumbens and hilus of dentate gyrus, but was diminished in the substantia nigra and cerebellum. On the other hand, in middle-aged animals, [3H]cyclic-AMP binding revealed a significant elevation only in the hippocampal CA3 sector, whereas [3H] rolipram binding showed a significant reduction in the thalamus and cerebellum. Thus, the age-related alteration in these binding sites showed different patterns among various brain regions in middle-aged gerbils indicating that the binding sites of PKC, IP3, and adenylate cyclase are more markedly affected by aging than those of PKA and cyclicAMP PDE and that the hippocampus and cerebellum are more susceptible to these aging processes than other brain regions. The findings suggest that in-tracellular signal transduction is affected at an early stage of senescence and this may lead to neurological deficits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01277949
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The synergy between Cu and ZnO in methanol synthesis catalysts (1996)
    Springer
    Catalysis letters 38 (1996), S. 157-163 
    Details
    ISSN: 1572-879X
    Keywords: methanol synthesis ; Cu/ZnO catalyst ; effect of reduction temperature ; oxygen coverage ; physical mixture ; Cu-Zn alloy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrogenation of CO2 over physically-mixed Cu/SiO2 and ZnO/SiO2 was carried out to clarify the synergetic effect between Cu and ZnO in Cu/ZnO methanol synthesis catalysts. The activity of the physical mixtures significantly increased with increasing reduction temperature in the range of 573–723 K. TEM-EDX results definitely showed that ZnOx moieties migrated from ZnO/SiO2 particles onto the surface of Cu particles when the physical mixtures were reduced at high temperatures above 573 K. Upon the migration of the ZnOx species, the oxygen coverage on the surface of Cu, measured after the hydrogenation of CO2, increased with the reduction temperature. The results clearly showed that the synergetic effect of ZnO in the physical mixtures can be ascribed to the creation of active sites such as Cu+ which the ZnOx moieties stabilize on the Cu surface. Further, XRD results showed that the migrated ZnOx species partly dissolved into the Cu particles to form a Cu—Zn alloy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00806562
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  • 3
    Electronic Resource
    Electronic Resource
    Evidence for the migration of ZnOx in a Cu/ZnO methanol synthesis catalyst (1994)
    Springer
    Catalysis letters 27 (1994), S. 67-78 
    Details
    ISSN: 1572-879X
    Keywords: methanol synthesis ; Cu/ZnO catalyst ; Cu-Zn alloy ; effect of reduction temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The behavior and role of ZnO in Cu/ZnO catalysts for the hydrogenations of CO and CO2 were studied using XRD, TEM coupled with EDX, TPD and FT-IR. As the reduction temperature increased, the specific activity for the hydrogenation of CO2 increased, whereas the activity for the hydrogenation of CO decreased. The EDX and XRD results definitely showed that ZnO x (x = 0–1) moieties migrate onto the Cu surface and dissolve into the Cu particle forming a Cu-Zn alloy when the Cu/ZnO catalysts were reduced at high temperatures above 600 K. The content of Zn dissolved in the Cu particles increased with reduction temperature and reached ∼ 18% at a reduction temperature of 723 K. The CO-TPD and FT-IR results suggested the presence of Cu+ sites formed in the vicinity of ZnO x on the Cu surface, where the Cu+ species were regarded as an active catalytic component for methanol synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00806979
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Long-term observations in gerbil brain following transient cerebral ischemia: Autoradiographic and histological study (1993)
    Springer
    Metabolic brain disease 8 (1993), S. 181-195 
    Details
    ISSN: 1573-7365
    Keywords: transient ischemia ; dopamine D1 ; naloxone ; forskolin ; receptor autoradiography ; gerbil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We investigated the long-term changes that occur in the gerbil brain following transient cerebral ischemia using histology and receptor autoradiography. Transient ischemia was induced for 3 and 10 min, and animals were allowed to survive for 8 months. A histological study showed that 3-min ischemia caused neuronal damage and mild atrophy only in the hippocampal CA1 sector, and that 10-min ischemia produced severe neuronal damage and marked shrinkage in the hippocampal CA1 and CA3 sectors. Furthermore, severe neuronal damage was seen in the striatum after 10-min ischemia. Autoradiography study revealed that 3-min ischemia caused a significant reduction in [3H] naloxone binding in the frontal cortex, striatum, dentate gyrus, and thalamus, whereas [3H]SCH 23390 and [3H] forskolin binding was not significantly altered in all regions, In contrast, 10-min ischemia produced marked alteration in these binding sites in the striatum, hippocampus, thalamus, and substantia nigra. The alteration was especially notable in the hippocampal region and substantia nigra. These results indicate that hippocampal damage after transient ischemia, compared with that in other regions, is not static, but particularly progressive. Furthermore, they demonstrate a reduction in adenylate cyclase system in the striatum and substantia nigra after transient ischemia. Moreover, our results suggest that long-term survival after ischemia may induce synaptic modification of neurotransmitter and adenylate cyclase system in the hippocampus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00996929
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    Paper (German National Licenses)
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