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  • 1
    Digitale Medien
    Digitale Medien
    In vivo activation of N-methyl-d-aspartate receptors in the rat hippocampus increases prostaglandin E2 extracellular levels and triggers lipid peroxidation through cyclooxygenase-mediated mechanisms (2002)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 81 (2002), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Cyclooxygenases (COX) are a family of enzymes involved in the biosynthesis of prostaglandin (PG) and thromboxanes. The inducible enzyme cyclooxygenase-2 (COX-2) is the major isoform found in normal brain, where it is constitutively expressed in neurons and is further up-regulated during several pathological events, including seizures and ischaemia. Emerging evidence suggests that COX-2 is implicated in excitotoxic neurodegenerative phenomena. It remains unclear whether PGs or other products associated to COX activity take part in these processes. Indeed, it has been suggested that reactive oxygen species, produced by COX, could mediate neuronal damage. In order to obtain direct evidence of free radical production during COX activity, we undertook an in vivo microdialysis study to monitor the levels of PGE2 and 8-epi-PGF2α following infusion of N-methyl-d-aspartate (NMDA). A 20-min application of 1 mm NMDA caused an immediate, MK-801-sensitive increase of both PGE2 and 8-epi-PGF2α basal levels. These effects were largely prevented by the specific cytosolic phospholipase A2 (cPLA2) inhibitor arachidonyl trifluoromethyl ketone (ATK), by non- selective COX inhibitors indomethacin and flurbiprofen or by the COX-2 selective inhibitor NS-398, suggesting that the NMDA-evoked prostaglandin synthesis and free radical-mediated lipid peroxidation are largely dependent on COX-2 activity. As several lines of evidence suggest that prostaglandins may be potentially neuroprotective, our findings support the hypothesis that free radicals, rather than prostaglandins, mediate the toxicity associated to COX-2 activity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.2002.00897.x
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  • 2
    Digitale Medien
    Digitale Medien
    A cellular automata model for highway traffic (2000)
    Springer
    The European physical journal 17 (2000), S. 159-166 
    Details
    ISSN: 1434-6036
    Schlagwort(e): PACS. 05.45.-a Nonlinear dynamics and nonlinear dynamic systems - 45.70.Vn Granular models of complex systems; traffic flow - 89.40.+k Transportation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: We present results relative to a simple cellular automata model without periodic boundary conditions for an highway with on-ramps. Simulations performed with this model reproduce experimental phenomena observed in traffic such as free flow, synchronized flow, congested flow, lane inversion, forward and backward propagating waves. On-ramps play the important role of nucleation points for the dynamic features of traffic.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100510070172
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  • 3
    Digitale Medien
    Digitale Medien
    Self-similarity in highway traffic (2002)
    Springer
    The European physical journal 25 (2002), S. 245-251 
    Details
    ISSN: 1434-6036
    Schlagwort(e): PACS. 05.45.Df Fractals – 45.70.Vn Granular models of complex systems; traffic flow
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: Highway traffic as simulated with a simple cellular automata model has been analysed in a search for self-similarity in the behaviour of car density and car flow as a function of space. Fractal dimensions between 1.5 and 1.6, depending on the simulation characteristics, have been measured with a box counting algorithm. The self-similarity spans over about 2 orders of magnitude. A comparison with experimental data is suggested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1140/epjb/e20020028
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  • 4
    Digitale Medien
    Digitale Medien
    Auditory nerve and brain stem responses in homozygous jaundiced gunn rats (1981)
    Springer
    European archives of oto-rhino-laryngology and head & neck 232 (1981), S. 139-143 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Hörnerv ; Hirnstamm ; Ratte ; Gelbsucht ; Hyperbilirubinämie ; Cochlea-Mikrophonpotentiale ; Auditory nerve ; Brain stem ; Gunn rats ; Jaundice ; Hyperbilirubinemia ; Cochlear microphonic
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary In humans, functional evidence based on recording cochlear microphonic, auditory nerve, and brain stem responses has shown that the site of lesion in hearing loss following neonatal hyperbilirubinemia is the auditory nerve (with sparing of the hair cells). Structural damage to the central nervous system (CNS) including the cochlear nuclei has been demonstrated in adult, homozygous Gunn rats which develop hyperbilirubinemia shortly after birth. In an attempt to use the Gunn rat as an experimental model for bilirubin-induced CNS damage, auditory nerve and brain stem responses (ABR) were recorded in jaundiced (homozygous) and non-jaundiced (heterozygous) Gunn rats and in Sabra (Wistar) rats. All of the rats including the jaundiced Gunn rats had normal ABR and responded behaviorally to sound stimuli. These results suggest that the adult jaundiced Gunn rat retains auditory function and in this way differs from human patients in whom neonatal jaundice has lead to hearing loss. Therefore, the adult homozygous Gunn rat probably cannot serve as a model for hearing loss due to hyperbilirubinemia.
    Notizen: Zusammenfassung Der Versuch, Ratten als experimentelles Modell eines durch Bilirubin verursachten Schadens im ZNS einzusetzen, zeigte, daß bei allen Ratten mit Gelbsucht normale Reaktionen des Hörnervs und des Hirnstamms auf akustische Reize zu registrieren waren. Da sich so die Reaktionen auf akustische Stimuli bei erwachsenen Ratten mit Gelbsucht von denen beim Menschen mit Ikterus neonatorum unterscheiden, sind Ratten nicht als Modell zur Untersuchung einer durch Hyperbilirubinämie verursachten Hörstörung geeignet.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00505033
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  • 5
    Digitale Medien
    Digitale Medien
    Transformations of simple ethers on dehydrating catalysts Communication 3. Effect of surface acidity on catalytic activity (1982)
    Springer
    Russian chemical bulletin 31 (1982), S. 752-757 
    Details
    ISSN: 1573-9171
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Conclusions 1. The introduction of titanium and silicon oxides into Al2O3 as well as its treatment with inorganic acids leads to an increase in the rate of disproportionation of simple ethers. The greatest increase in the rate, by a factor of almost 5 times, is observed in the case of aluminum oxide samples which have been treated with TiCl4, and HCl. 2. A parallel change was discovered in the rate of disproportionation and the surface acidity measured using the chemisorption of ammonia at 200°C as a function of the amounts of TiCl4, and HCl introduced. 3. On the basis of the data which had been obtained the proposal was made that the presence of Lewis acid centers is the main factor determining the activity of the catalysts in the disproportionation of simple ethers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00950012
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