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  • 1
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 23 (1974), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: —In contrast with neurotoxic organophosphates of the type (RO)2P.O.X several phosphinates (R2P.O.X) cause prolonged inhibition of ‘neurotoxic esterase’in vivo but do not cause delayed neurotoxicity even after repeated administration. Prior administration of these phosphinates protected hens against the neurotoxic effects of several organophosphates: this protection lasted until about 70 per cent of the enzyme site again became available for phosphorylation. In this respect phosphinates behave like carbamate and sulphonyl fluoride inhibitors of ‘neurotoxic esterase'. It is proposed that the development of delayed neurotoxicity requires phosphorylation of the esterase followed by hydrolysis of one remaining phosphoryl ester bond to produce a charged monosubstituted phosphoric acid group attached to the protein. Generation of such a group could not occur after inhibition by the protective phosphinates, carbamates or sulphonates. It is proposed that the charged group is responsible for the metabolic disturbance leading to degeneration of long axons.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 32 (1979), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neurotoxic esterase (NTE) is now regarded as the site of the primary biochemical lesion in the delayed neuronal degeneration produced by certain organophosphorus esters. Since hens are the species of choice in studies of this neuropathy the subcellular distribution of NTE and marker enzymes in adult hen brain was carried out. Up to 70%, of NTE was recovered in a microsomal fraction (P3) which was also enriched in 5′-nucleotidase (5′-ribonucleotide phosphohydrolase EC 3.1.3.5), a plasma membrane marker. The protein content of this fraction (31% of the parent homogenate) is double that of equivalent mammalian brain fractions. The LDH distribution suggests that the P3 fraction contained many small synaptosomes. Subfractionation of microsomes by rate and equilibrium centrifugation on sucrose density gradients segregated the RNA but failed to separate the NTE. 5′-nucleotidase and glucose-6-phosphatase (D-glucose-6-phosphate phosphohydrolase EC 3.1.3.9) from each other. NTE was considerably concentrated (2–5 times) in subfractions of the P2 fraction, which are believed to be enriched in synaptosomal membranes. A similar localization of NTE and AChE was found in subfractions of P2 from neonatal chick brain. Axon fragments contained a significant amount of NTE which was not associated with the myelin. Nuclear and mitochondrial fractions were low in NTE. Microsomes could be partitioned in biphasic aqueous polymer systems, but with little enrichment of NTE. The possible association of NTE with synaptosomal membranes suggests that early events in organophosphorus neuropathy may occur at the axonal (? synaptic) surface.
    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 160 (1969), 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
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Psychology 38 (1987), S. 631-668 
    ISSN: 0066-4308
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Psychology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 222 (1969), S. 1066-1067 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Previous work in this laboratory has identified a protein in chicken nervous tissue which is phosphorylated in vivo by neurotoxic organophosphorus esters, but not by non-neurotoxic analogues2'3. In vitro this protein can hydro-lyse the phenyl ester of 1-phenylacetic acid (PPA)4'5. Although the ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 196 (1962), S. 1210-1211 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] 100 per cent recovery of activity is necessary in meaningful distribution studies and is usually, though not necessarily, achieved most easily when each fraction sample is made to show the maximum activity of which it is capable with the chosen assay system. For fractions obtained from brain ...
    Type of Medium: Electronic Resource
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  • 9
    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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  • 10
    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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