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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 34 (1975), S. 259-288 
    ISSN: 1432-0738
    Keywords: Organophosphates ; Neurotoxicity ; Mechanism ; Structure/Activity ; Organophosphate ; Neurotoxizität ; Wirkungsmechanismus ; Struktur-Aktivitätsbeziehungen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Wirkungsmechanismus Die Beweisführung nimmt an, daß die Phosphorylierung des aktiven Zentrums eines spezifischen Enzyms, “neurotoxische Esterase” genannt, das initiale biochemische Ereignis der zur verzögerten Neurotoxizität führenden Reaktionsfolge ist. Darauf folgt die Spaltung einer Bindung (hydrolytisch?) die einen monosubstituierten Phosphorsäurerest am Protein hinterläßt. — Der Mechanismus, auf dem die Schutzwirkung einiger Phosphonsäureester gegenüber neurotoxischen Substanzen beruht, wird erläutert. Screening-Methode Die Bestimmung der Wirkung auf die Aktivität der “neurotoxischen Esterase” im Hühnergehirn (in vitro und in vivo) stellt eine schnelle biochemische Probe zur Ergänzung des 3wöchigen klinischen Tests dar. Der Test erlaubt die Abschätzung von Sicherheitsgrenzen für Substanzen, die negative Ergebnisse im klinischen Test erbringen und häufig als Pestizide, Weichmacher usw. verwendet werden. Vereinfachte Bestimmungsmethoden wurden entwickelt. Struktur-Wirkungs-Eeziehungen Für viele Verbindungen liegen Daten über die biochemische und neurotoxische Wirkung vor. Diese dienen als Basis für Vorhersagen von Struktur-Wirkungs-Beziehungen. Die seit 1930 veröffentlichten Daten zur Neurotoxizität werden unter diesem Gesichtspunkt behandelt.
    Notes: Abstract Mechanism of Action Evidence is reviewed that the initial biochemical event leading to delayed neurotoxicity is phosphorylation of the active site of a specific enzyme called Neurotoxic Esterase. This is followed by a bondcleavage (? hydrolytic) leading to formation of a mono-substituted phosphoric acid residue on the protein. The mechanism by which some phosphinates protect hens against neurotoxic compounds is explained. Screening Assay Assay of effects of compounds on Neurotoxic Esterase activity of hen brain in vitro and in vivo provides a quick biochemical screen to supplement the 3-week clinical test. This test provides an estimate of safety margin for compounds which give negative results in the clinical test and are currently used as pesticides, plasticisers, etc. Simplified assay procedures are being developed. Structure/Activity Studies Data is now available for the biochemical and neurotoxic activity of many compounds. This provides a basis for structure/activity predictions; neurotoxicity data published since 1930 has been assessed in this light.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 45 (1980), S. 263-271 
    ISSN: 1432-0738
    Keywords: Organophosphate neuropathy ; Organophosphate ; Chronic dosing ; Neurotoxic esterase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of small repeated oral doses of mono-2-cresyl diphenyl phosphate (MOCP, 2.5 mg/kg/day) on hen brain and spinal cord neurotoxic esterase (NTE) were measured. The enzyme levels were depressed to about 40% and 55% of normal respectively and maintained at that level for 8 weeks. No clinical and only doubtful histological signs of neuropathy were detected. Neuropathy could be precipitated by depressing the level to 〈 20% either with a single high dose (50 mg/kg), or by an increase of the repeated dose level to 5 mg/kg/day. There was no correlation between inhibition of NTE in the nervous tissue and the “NTE-like” activity in lymphocytes. “NTE-like” activity in spleen was consistently inhibited but to a lesser extent than that in the brain or spinal cord. Brain AChE and BuChE were not affected.
    Type of Medium: Electronic Resource
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