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  • 1
    Electronic Resource
    Electronic Resource
    Metabolism of pentachlorophenol in vivo and in vitro (1978)
    Springer
    Archives of toxicology 40 (1978), S. 45-53 
    Details
    ISSN: 1432-0738
    Keywords: Metabolism ; Glucuronide ; Rats ; Microsomes ; Mass fragmentography ; Pentachlorophenol ; Tetrachloro-p-hydroquinone ; Phenobarbital ; β-Diethylaminoethyldiphenyl propylacetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Wie in früheren Versuchen gezeigt worden ist, wird Pentachlorphenol bei Säugern zu Tetrachlor-p-Hydrochinon metabolisiert. Dieser Metabolit wirkt ausgeprägt hemmend auf Bakterien-β-Glucuronidase, aber nicht auf Leber-β-Glucuronidase. Ein indirekter Beweis für das Vorkommen von sowohl Pentachlorphenol als auch Tetrachlor-p-Hydrochinon als Konjugate mit Glucuronsäure im Harn von pentachlorphenolbehandelten Ratten wird nun vorgelegt. Zur Spaltung der gegenwärtigen Konjugate wurde Rinderleber-β-Glucuronidase benutzt. Der in vivo-Abbau von Pentachlorphenol wurde auch an mit phenobarbital und mit β-Diäthylaminoäthyl-Diphenyl-Propylacetat (SKF 525-A) behandelten Ratten untersucht. Beim Studium des in vitro-Abbaus wurden Lebermikrosomen von mit Phenobarbital behandelten Ratten benutzt. Phenobarbital steigerte die Umwandlung in Tetrachlor-p-Hydrochinon sowohl in vivo als auch in vitro. SKF 525-A verzögerte indessen den in vitro-Umsatz, steigerte ihn jedoch in vivo, wenn weniger oft als alle 6 Std gegeben. Die Untersuchung zeigt also, daß die Entchlorung von Pentachlorphenol durch Mikrosomenenzyme vermittelt wird, die durch phenobarbital angeregt werden können. SKF 525-A hemmt die Entchlorung nicht in vivo, wohl aber in vitro.
    Notes: Abstract Pentachlorophenol has earlier been shown to be metabolized in mammals to tetrachloro-p-hydroquinone. The metabolite possesses pronounced inhibitory activity on bacterial β-glucuronidase but not on β-glucuronidase from liver. Indirect evidence for the occurrence of both pentachlorophenol and tetrachloro-p-hydroquinone as conjugates with glucuronic acid in the urine from pentachlorophenol-treated rats is now presented. Bovine liver β-glucuronidase has been utilized to split the conjugates present. The in vivo metabolism of pentachlorophenol has also been studied in rats treated with phenobarbital and β-diethylaminoethyldiphenyl propylacetate (SKF 525-A). In vitro metabolism has been studied using liver microsomes from rats pretreated with phenobarbital. Quantitative analysis of the compounds occurring in extracts of urine or extracts from the microsomal incubates was performed by means of mass fragmentography. Pretreatment with phenobarbital increased the metabolism of pentachlorophenol to tetrachloro-p-hydroquinone both in vivo and in vitro. SKF 525-A, however, inhibited the metabolism in vitro but enhanced the metabolism in vivo when given less frequently than every 6th h. Dechlorination of pentachlorophenol is mediated by microsomal enzymes that can be induced by phenobarbital. SKF 525-A does not inhibit the dechlorination in vivo but does so in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00353278
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on the in vivo and in vitro dechlorination of pentachlorophenol (1978)
    Springer
    Archives of toxicology 40 (1978), S. 55-61 
    Details
    ISSN: 1432-0738
    Keywords: Metabolism ; Dechlorination ; Urinary excretion ; Rats ; Microsomes ; Pentachlorophenol ; Tetrachloro-p-hydroquinone ; Trichloro-p-hydroquinone ; 2,3,7,8-tetrachlorodibenzo-p-dioxin ; β-diethylaminoethyl-diphenyl propylacetate ; phenobarbital ; 3-methylcholanthrene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Der Metabolismus von Pentachlorphenol nach Vorbehandlung der Versuchstiere (Ratten) mit phenobarbital, 3-Methylcholantren oder 2,3,7,8-Tetrachlordibenzo-p-Dioxin (TCDD) ist untersucht worden. Zu dem schon früher nachgewiesenen Metaboliten Tetrachlor-p-Hydrochinon wurde nun auch Trichlor-p-Hydrochinon als Harnmetabolit festgestellt. Die Bildung des letzteren stellt eine andere Art von Dechlorierung dar als diejenige die bei der Entstehung von Tetrachlor-p-Hydrochinon vorliegt. 3-Methylcholantren und TCDD haben ähnlichen Einfluß auf die Dechlorierung und steigern die Bildung von Tetrachlor-p-Hydrochinon mehr ausgeprägt als es bei phenobarbital der Fall ist. Im Gegensatz zu phenobarbital steigern sie auch die Bildung von Tri-chlor-p-Hydrochinon sowie die totale Eliminierung von Pentachlorphenol und von Metaboliten. Die in vivo-Befunde werden von in vitro-Studien mit Mikrosomen von mit phenobarbital oder TCDD vorbehandelten Ratten gestützt. Anwendung des Inhibitors β-Diethylaminoethyl-Diphenyl-Propylacetat (SKF 525-A) zeigte in vitro eine ausgeprägtere Inhibition der Mikrosomen von mit phenobarbital behandelten Ratten als der Mikrosomen von unbehandelten oder TCDD-behandelten Ratten. Nachweis und Bestimmung von Pentachlorphenol und seinen Metaboliten wurden gaschromatographisch-massenspektrometrisch durchgeführt.
    Notes: Abstract The metabolism of pentachlorophenol has been studied in the rat after pretreatments with phenobarbital, 3-methyl-cholanthrene or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In addition to the previously identified metabolite, tetrachloro-p-hydroquinone, trichloro-p-hydroquinone has been identified in urine as a metabolite. The formation of the latter represents a type of dechlorination different from that of the formation of tetrachlorohydroquinone. The inducing agents, 3-methylcholanthrene and TCDD have similar effects on the dechlorination and increase the formation of tetrachloro-p-hydroquinone more pronounced than does phenobarbital. In contrast to phenobarbital they also increase the formation of trichloro-p-hydroquinone and the total elimination of pentachlorophenol and its metabolites. The in vivo findings are supported by in vitro studies with microsomes from rats pretreated with phenobarbital or TCDD. Use of the inhibitor β-diethylaminoethyl-diphenyl propylacetate (SKF 525-A) in vitro showed a more pronounced inhibition on microsomes from phenobarbital-treated rats than on microsomes from untreated or TCDD-treated rats. Gas chromatography-mass spectrometry have been used for the identification and quantification of pentachlorophenol and its metabolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00353279
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  • 3
    Electronic Resource
    Electronic Resource
    Vitamin A (retinol) status in the Gunn rat (1983)
    Springer
    Archives of toxicology 53 (1983), S. 225-233 
    Details
    ISSN: 1432-0738
    Keywords: Vitamin A ; Retinol ; Gunn rat ; UDP-Glucuronosyltransferase ; Liver ; Serum ; 2,3,7,8-Tetrachlorodibenzo-p-dioxin ; TCDD ; High performance liquid chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Vitamin A (retinol) status and the effect of a single oral dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 10 μg × kg−1, on vitamin A in the liver and serum, and on the hepatic UDP-glucuronosyltransferase (UDPGT) (EC 2.4.1.17) activity, were studied in heterozygous (GW) and homozygous (GG) Gunn rats. 1) Data from vitamin A analyses demonstrate that the amount of vitamin A stored in the liver of untreated Gunn rats is of the same magnitude as that of Sprague-Dawley rats. 2) The retinol content in the liver of both GG and GW rats was reduced to about 50% by TCDD-treatment. 3) Retinol levels in serum were found to be variable and no significant effect due to TCDD could be observed. 4) No correlation between the TCDD-induced reduction of vitamin A and the induction of UDPGT activity by TCDD could be demonstrated in this study. The vitamin A reduction caused by TCDD was considerably less in the Gunn rat than in the Sprague-Dawley rat, and the results indicate that the Gunn rat is more resistant to TCDD than other strains of rat. TCDD-induced reduction of liver vitamin A seems to some extent to correlate with TCDD-toxicity in different strains of rat. The specific properties of the Gunn rat and its relatively high resistance to TCDD make it a valuable tool in studies about the mechanism of TCDD-toxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316506
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  • 4
    Electronic Resource
    Electronic Resource
    Erratum (1981)
    Springer
    Archives of toxicology 47 (1981), S. 245-246 
    Details
    ISSN: 1432-0738
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368685
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on the hepatic storage of retinol in rats with different dietary supplies of vitamin A (retinol) (1980)
    Springer
    Archives of toxicology 45 (1980), S. 273-285 
    Details
    ISSN: 1432-0738
    Keywords: Rats ; 2,3,7,8-Tetrachlorodibenzo-p-dioxin ; Vitamin A ; Diet ; Retinol ; Liver ; High pressure liquid chromatography ; UDP-Glucuronosyltranferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Der Einfluß verschieden hoher Gaben von Vitamin A auf die Retinolspeicherung der Leber bei Sprague-Dawley Ratten, die unterschiedliche Dosen von 2,3,7,8-Tetrachlordibenzo-p-dioxin (TCDD) erhalten haben, ist untersucht worden. Jede Dosierungsgruppe bestand aus drei Untergruppen, die jeweils eine Kost mit normalem, mit erniedrigtem und mit erhöhtem Retinolgehalt verabreicht bekamen. Vier Wochen nach der TCDD-Zufuhr wurden Retinolgehalt und Glucuronosyl-Transferase-Aktivität mit Hilfe der Hoch-druckflüssigkeitschromatographie bzw. spektrofotometrisch bestimmt. Eine dosierungsabhängige Abnahme der Retinolspeicherung in der Leber war deutlich. Die Hochretinolkost war nicht fähig, die durch die höchste TCDD-Gabe verursachte Senkung ganz auszugleichen. Die Glucuronosyl-Transferase-Aktivität wuchs linear mit der TCDD-Dosis, war aber auch umgekehrt proportional mit dem Retinolgehalt der Kost.
    Notes: Abstract The effect of various dietary sources of vitamin A on liver storage of retinol has been investigated in Sprague-Dawley rats treated with single oral doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD): 0, 0.1, 1.0, or 10 μg · kg−1. Each dose group consisted of 3 subgroups, each comprising 10 rats which received a diet with normal, low or high retinol content. The animals were killed 4 weeks after TCDD administration. Analyses of retinol were performed by high pressure liquid chromatography and glucurono-syltransferase activities were determined spectrophotometrically. A dose-dependent decrease in hepatic storage of retinol was evident. The high retinol diet did not fully compensate for the reduction caused by the highest TCDD-dose. Glucuronosyltransferase activity increased directly in relation to the TCDD-dose but in inverse proportion to the retinol content of the diet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293808
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  • 6
    Electronic Resource
    Electronic Resource
    Vitamin A (retinol) status in the rat after a single oral dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (1979)
    Springer
    Archives of toxicology 42 (1979), S. 265-274 
    Details
    ISSN: 1432-0738
    Keywords: Rats ; 2,3,7,8-tetrachlorodibenzo-p-dioxin ; Vitamin A ; Retinol ; Liver ; Serum ; Spectrophotometry ; High pressure liquid chromatography ; Ratten ; 2,3,7,8-Tetrachlordibenzo-p-dioxin ; Vitamin A ; Retinol ; Leber ; Serum ; Spektrofotometrie ; Hochdruckflüssigkeitschromatographie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Der Einfluß einer oralen Einzeldosis von 2,3,7,8-Tetrachlordibenzo-p-dioxin (TCDD), 10 μg · kg−1, auf den Vitamin A (Retinol)-Statu wurde an Ratten 8 Wochen lang nach der Verabreichung untersucht. Das Retinol wurde spektrofotometrisch nach Trennung mit Hilfe von Hochdruckflüssigkeitschromatographie bestimmt. In den Lebern der Kontrolltiere stieg die Totalspeicherung und Konzentration von Retinol linear mit der Zeit an, während in den TCDD exponierten Tieren sowohl die Konzentration als auch die Totalspeicherung im wesentlichen unverändert blieben. Unterschiede in der Speicherung waren schon nach 4 Tagen ersichtlich und nach 8 Wochen wiesen die exponierten Tiere nur noch 30% der totalen Leberspeicherung, verglichen mit der der Kontrollgruppe, auf. Der Retinolspiegel im Serum war in den exponierten Tieren ab Woche 2 und 3 signifikant höher.
    Notes: Abstract The effect of a single oral dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 10 μg · kg−1, on the status of vitamin A (retinol) was studied in rats during an eight week period after administration. Retinol was determined spectrophotometrically after separation by means of high pressure liquid chromatography. In the liver of control animals the total storage and the concentration of retinol were found to increase linearly with time whilst in the TCDD-exposed animals both the concentration and total storage remained essentially unchanged. Differences in the storage levels were evident after 4 days, and after 8 weeks the treated animals had a total liver storage corresponding to about 30% of the controls. Retinol levels in serum were significantly higher in the treated animals after week 1 and 2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334840
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  • 7
    Electronic Resource
    Electronic Resource
    Comparison between the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin and six other compounds on the vitamin A storage, the UDP-glucuronosyltransferase and the aryl hydrocarbon hydroxylase activity in the rat liver (1984)
    Springer
    Archives of toxicology 55 (1984), S. 16-19 
    Details
    ISSN: 1432-0738
    Keywords: TCDD ; 2,3,7,8-Tetrachlorodibenzo-p-dioxin ; 3-Methylcholanthrene ; Phenobarbital ; 2,3,7,8-Tetrabromodibenzo-p-dioxin ; Toxaphene ; 5-Chloro-2-(2,4-dichlorophenoxy)phenol ; 4,5,6-Trichloro-2-(2,4-dichlorophenoxy)phenol ; Vitamin A ; Retinol ; UDP-glucuronosyltransferase ; Aryl hydrocarbon hydroxylase ; Liver ; Rat ; High pressure liquid chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrabromodibenzo-p-dioxin (TBrDD), 5-chloro-2-(2,4-dichlorophenoxy)phenol(3-Cl-predioxin) 4,5,6-trichloro-2-(2,4-dichlorophenoxy)phenol (5-Cl-predioxin), toxaphene, 3-methylcholanthrene (3-MC) and phenobarbital (PB) on the vitamin A storage, UDP-glucuronosyltransferase (UDPGT) and aryl hydrocarbon hydroxylase (AHH) activities in the liver of Sprague-Dawley rats was investigated. Vitamin A was determined as retinol by high pressure liquid chromatography. UDPGT was measured with p-nitrophenol as an aglycone and AHH with 3,4-benzopyrene as a substrate. Both in TCDD- and toxaphene-treated animals a reduced body weight gain was recorded, but no other overt signs of toxicity were seen in this study. Both the concentration and the total amount of hepatic retinol was significantly reduced in TCDD-, 3-MC-, PB- and TBrDD-treated animals. These compounds were also those which gave the most significant enzyme induction as regards the UDPGT and AHH activities. However, the reduction of hepatic retinol caused by these compounds did not correlate with the enzyme activities studied. When compared on a molecular basis, TCDD and TBrDD were in the order of several magnitudes more potent as reducers of hepatic retinol and likewise as enzyme inducers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316580
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  • 8
    Electronic Resource
    Electronic Resource
    Inhibition of β-glucuronidase by chlorinated hydroquinones and benzoquinones (1977)
    Springer
    Archives of toxicology 37 (1977), S. 81-87 
    Details
    ISSN: 1432-0738
    Keywords: β-Glucuronidase ; Inhibition ; Chlorobenzoquinones ; Chlorohydroquinones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Eine frühere Studie des Metabolismus von Pentachlorphenol hat gezeigt, daß ein Metabolit, Tetrachlor-p-hydrochinon, eine ausgesprochene Hemmwirkung auf die Aktivität der Bakterien-β-Glucuronidase besitzt. Verschiedene andere chlorierte Hydrochinone und Benzochinone sind jetzt auf ihre Fähigkeit, β-Glucuronidase anderen Ursprungs zu hemmen, in vitro und in vivo, untersucht worden. Alle die untersuchten chlorierten Hydrochinone und Benzochinone zeigten sich als starke Hemmer der Bakterien β-Glucuronidase. D-Glucarsäure-1.4-Lakton wurde zum Vergleich einbezogen und wurde weniger aktiv als die anderen Verbindungen befunden. Die Hemmung war kompetitiver Art. Kein Hemmungseffekt von Hydro-oder Benzochinonen konnte in vitro oder in vivo auf Leber-β-Glucuronidase gezeigt werden. Das Resultat mahnt zur Vorsieht, wenn Bakterien β-Glucuronidase zur Spaltung von Harnkonjugaten der Glucuronsäure angewandt wird.
    Notes: Abstract An earlier study of the metabolism of pentachlorophenol has shown that a metabolite, tetrachloro-p-hydroquinone, possessed pronounced inhibitory action on the activity of β-glucuronidase from bacterial origin. Several other chlorinated hydroquinones and benzoquinones have now been studied with regard to their ability to inhibit β-glucuronidase of various origin in vitro and in vivo. All the studied chlorinated hydroquinones and benzoquinones were found to be potent inhibitors of β-glucuronidase of bacterial origin. D-glucaric acid-1.4-lactone was included for comparison and was found to be less active than the other studied compounds. The inhibition was found to be competitive in nature. No inhibitory effect of the benzo- and hydroquinones studied in vitro or in vivo could be demonstrated on β-glucuronidase from livers. The result calls for precaution when using bacterial β-glucuronidase to split urinary conjugates of glucuronic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293856
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