Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-1335
    Keywords: Key words Chemical carcinogens ; List of MAK and BAT values ; Cancer risk ; carcinogen classification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Carcinogenic chemicals in the work area were previously classified into three categories in section III of the German List of MAK and BAT values (the list of values on maximum workplace concentrations and bio‐logical tolerance for occupational exposures). This classification was based on qualitative criteria and reflected essentially the weight of evidence available for judging the carcinogenic potential of the chemicals. In the new classification scheme the former sections IIIA1, IIIA2, and IIIB are retained as categories 1, 2, and 3, to correspond with European Union regulations. On the basis of our advancing knowledge of reaction mechanisms and the potency of carcinogens, these three categories are supplemented with two additional categories. The essential feature of substances classified in the new categories is that exposure to these chemicals does not contribute significantly to the risk of cancer to man, provided that an appropriate exposure limit (MAK value) is observed. Chemicals known to act typically by non-genotoxic mechanisms, and for which information is available that allows evaluation of the effects of low-dose exposures, are classified in category 4. Genotoxic chemicals for which low carcinogenic potency can be expected on the basis of dose/response relationships and toxicokinetics and for which risk at low doses can be assessed are classified in category 5. The basis for a better differentiation of carcinogens is discussed, the new categories are defined, and possible criteria for classification are described. Examples for category 4 (1,4-dioxane) and category 5 (styrene) are presented.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-0738
    Keywords: Chenodeoxycholic acid ; Chimpanzee ; Conjugation ; Lithocholic acid ; Sulfation ; Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Um im Schimpansen die hepatische Biotransformation der primären Gallensäure Chenodeoxycholsäure und deren wichtigstem bakteriellen Metaboliten, Lithocholsäure zu charakterisieren, wurde ein Gemisch aus Spurenmengen von14C-Lithocholsäure und3H-Chenodeoxycholsäure intravenös in zwei Tiere mit Gallenfistel injiziert. Die chemische Form der Radioaktivität, die in der Galle erschien, wurde dünnschichtchromatographisch ermittelt. Etwa 80% der Chenodeoxycholsäure und 70% der Lithocholsäure wurden innerhalb von 90 min ausgeschieden. Die Chenodeoxycholsäure war vollständig konjugiert und erschien vorwiegend als Chenyltaurin (52%) und Chenylglycin (37%). 11% erschienen in einer Form, die bisher nicht identifiziert wurde. Lithocholsäure wurde vollständig als Taurin- und Glycinkonjugat in die Galle eliminiert; der größte Teil (63%) war zusätzlich sulfatiert. Die Sulfatierung nahm stetig mit der Zeit zu und Lithocholylglycine wurde stärker sulfatiert als Lithocholyltaurin. Wir schließen aus diesen Befunden, daß der Schimpanse mit dem Menschen vergleichbar ist, indem er Lithocholsäure effektiv sulfatiert. Dadurch unterscheidet sich der Schimpanse vom Rhesusaffe und Baboon, die die Lithocholsäure nur in geringem Maße sulfatieren. Jedoch unterscheidet sich der Schimpanse auch vom Menschen und ähnelt dem Rhesusaffen und dem Baboon, indem er Gallensäure vorwiegend mit Taurin konjugiert. Die Ergebnisse lassen den Schluß zu, daß die Hepatotoxizität, die im Rhesusaffe und Baboon durch Chenodeoxycholat hervorgerufen wird, und auf eine geringe Sulfatierung der Lithocholsäure zurückgeführt wird, beim Schimpansen nicht bestehen sollte.
    Notes: Abstract To characterize the hepatic biotransformation in the chimpanzee of the primary bile acid chenodeoxycholic acid (chenic) and its major bacterial metabolite lithocholic acid (lithocholic) a mixture of tracer amounts of14C-lithocholic and3H-chenic was injected intravenously into two animals with a bile fistula; the chemical form of radioactivity appearing in bile was inferred using thin layer chromatography. About 80% of chenic, and 70% of lithocholic was recovered in 90 min. Chenic was completely conjugated in bile, appearing predominantly as chenyltaurine (52%) and chenylglycine (37%). An unidentified conjugate (about 11%) was also found. Lithocholic was excreted completely as taurine and glycine conjugates, but the majority (63%) of conjugates was sulfated. Sulfation increased progressively with time, and lithocholylglycine was sulfated more than lithocholyltaurine. We conclude that the chimpanzee is similar to man in that the secondary bile acid lithocholic is efficiently sulfated. The chimpanzee thus differs from the baboon and rhesus monkey which sulfate lithocholic poorly. However, the chimpanzee differs from man and is similar to the baboon and rhesus monkey in showing preferential conjugation of bile acids with taurine. The results imply that hepatotoxicity caused by chenic, which is well documented in the rhesus monkey and baboon and has been related to defective lithocholic sulfation, should not occur in the chimpanzee.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...