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  • 1
    Electronic Resource
    Electronic Resource
    The characteristics of blood-brain barrier in three different conditions — infarction, selective neuronal death and selective loss of presynaptic terminals — following cerebral ischemia (1992)
    Springer
    Acta neuropathologica 84 (1992), S. 378-386 
    Details
    ISSN: 1432-0533
    Keywords: Blood-brain barrier ; Cerebral ischemia ; Albumin ; Synapsin I ; Microtubule-associated protein 2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We investigated the extravasation of serum albumin using immunohistochemistry in three different conditions, i.e., infarction, selective neuronal death and selective loss of presynaptic terminals following cerebral ischemia in gerbils. In selective neuronal death, which is typically found in the CA1 neurons of the hippocampus after 5-min bilateral cerebral ischemia, selective damage of postsynaptic components with intact presynaptic sites was demonstrated by immunohistochemical examination for microtubule-associated protein 2 and synapsin I, and albumin extravasation did not become apparent before postsynaptic structures were destroyed. In cerebral infarction, which was consistently observed in the thalamus after 15-min forebrain ischemia, massive albumin extravasation was visible early after ischemia due probably to the ischemic endothelial necrosis. In selective loss of presynaptic terminals, which was detected at the molecular layer of the dentate gyrus in the contralateral, nonischemic hippocampus after unilateral cerebral ischemia, immunoreaction for albumin was not visualized. Since endothelium and glial cells were intact in morphological aspects in selective damage of both pre- and postsynaptic sites, it was thought that extravasation was facilitated by the stimulation of endothelial cells and glial cells with unknown factors that were induced by the destruction of post- but not presynaptic elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227664
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  • 2
    Electronic Resource
    Electronic Resource
    Temporal profile of serum albumin extravasation following cerebral ischemia in a newly established reproducible gerbil model for vasogenic brain edema: a combined immunohistochemical and dye tracer analysis (1991)
    Springer
    Acta neuropathologica 82 (1991), S. 164-171 
    Details
    ISSN: 1432-0533
    Keywords: Gerbil ; Cerebral ischemia ; Vasogenic brain edema ; Immunohistochemistry ; Albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We investigated the temporal profile of the extravasation of serum albumin in a reproducible gerbil model of unilateral cerebral ischemia, using immunohistochemical and dye-tracer techniques to evaluate albumin accumulation and the occurrence of active extravasation, respectively. After 30 min of cerebral ischemia and subsequent reperfusion, immunostaining for albumin became visible in the lateral part of the thalamus during the first 3 h, and then expanded to other brain regions up to 24 h. At both 24 h and 3 days after reperfusion, massive extravasation of albumin was noted in the whole ischemic hemisphere, and this had decreased again by 7 days after reperfusion. The extent and the degree of albumin immunopositivity were almost the same in all animals examined at each period after reperfusion. The extravasation of Evans blue, which was allowed to circulate for 30 min before death, was limited to the lateral part of the thalamus during the first 6 h of reperfusion. In the circumscribed area of massive albumin extravasation, many neurons were immunopositive for albumin; most of these neurons appeared to be intact and also showed immunostaining for microtubule-associated protein 2. The current investigation clearly demonstrated that (1) albumin extravasation was produced with reliable reproducibility in this model, (2) the lateral part of the thalamus was the region most vulnerable to ischemic blood-brain barrier damage, and (3) many apparently intact neurons in the ischemic region were positive for albumin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294441
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Shape-selective alkylation of biphenyl over mordenites: effects of dealumination on shape-selectivity and coke deposition (1994)
    Springer
    Catalysis letters 26 (1994), S. 181-187 
    Details
    ISSN: 1572-879X
    Keywords: shape-selective catalysis ; biphenyl ; isopropylation ; H-mordenite ; carbonaceous deposits ; encapsulated biphenyls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract To understand the relationships between shape-selectivity and coke deposition in the alkylation of biphenyl over H-mordenite (HM), thermogravimetric analyses were examined for the catalyst after the reaction. The coke deposition during the catalysis was very severe over HM with low SiO/Al2O3 ratio, however, dealumination enhanced the decrease of coke deposition. Over highly dealuminated HM, volatile organic compounds, mainly biphenyl derivatives, were observed in addition to carbonaceous deposits. The deposits are produced from biphenyl derivatives on acid sites in the HM pore, and the ease of their formation is governed by acid site density and acid strength. The decrease of carbonaceous deposits and the increase of encapsulated biphenyl derivatives are related with the increase of both selectivity and yield of 4,4′-diisopropylbiphenyl (4,4′-DIPB). The increase of reaction temperature up to 250°C enhanced the catalysis over highly dealuminated HM, however, further increase of the temperature resulted in extensive decrease of the selectivity of 4,4′-DIPB. Coke deposition also increased with the temperature although its level was low. The composition of 4,4′-DIPB in encapsulated DIPB isomers remained as high as 80% in spite of a change of the distribution of bulk products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00824043
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  • 4
    Electronic Resource
    Electronic Resource
    Shape-selective alkylation of biphenyl over mordenite: cerium exchanged sodium mordenite and unmodified H-mordenite with low SiO2/Al2O3 ratio (1994)
    Springer
    Catalysis letters 27 (1994), S. 315-322 
    Details
    ISSN: 1572-879X
    Keywords: Shape-selective catalysis ; biphenyl ; isopropylation ; cerium exchanged sodium mordenite ; H-mordenite ; propylene pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Liquid phase isopropylation of biphenyl with propylene was studied over a cerium exchanged sodium mordenite (Ce/NaM25) and a H-mordenite (HM25) with the same SiO2/Al2O3 ratio of 25. Shape-selective catalysis occurred to give 4,4′-diisopropylbiphenyl (4,4′-DIPS) in high selectivity over Ce/NaM25 under any propylene pressures. HM25 gave 4,4′-DIPS shape-selectively under high propylene pressures. However, the reaction was severely deactivated at a conversion of ca. 60% under such a low pressure as 0.8 kg/cm2 because of coke formation in the pore. The yields of 4-isopropylbiphenyl (4-IPBP) and 4,4′-DIPB decreased with the increase of those of 3-IPBP and 3,4′-DIPB because of non-selective alkylation and isomerization at external acid sites that are alive in spite of severe deactivation. No significant isomerization of 4,4′-DIPB over Ce/NaM25 was observed even at low propylene pressure. In the case of HM25, the isomerization of 4,4′-DIPB to 3,4′-DIPB occurred significantly under low propylene pressures, while it decreased under high pressure. These differences are ascribed to the differences of nature of acid sites between Ce/NaM25 and HM25 zeolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00813918
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    Paper (German National Licenses)
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