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Drug-metabolizing enzyme activities in freshly isolated oval cells and in an established oval cell line from carcinogen-fed rats (1994)

Steinberg, P. ; Steinbrecher, R. ; Schrenk, D. ; [et al.]

Springer

Cell biology and toxicology 10 (1994), S. 59-65

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ISSN: 1573-6822

Keywords: drug metabolism ; drug resistance ; hepatocarcinogenesis ; oval cells ; parenchymal cells

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract The activities of several different phase I and phase II drug-metabolizing enzymes were measured in freshly isolated oval cells from rats fed a choline-deficient/DL-ethionine-supplemented diet for 6 weeks and alsoin vitro in the established oval cell line OC/CDE 6. No cytochrome P450 was spectrophotometrically measurable in both preparations and two cytochrome P450-dependent monoxygenase activities, aminopyrineN-demethylase and ethoxyresorufinO-deethylase, could not be detected in the oval cells of both sources. However, cytosolic glutathione transferase, microsomal expoxide hydrolase and UDP-glucuronosyltransferase activities were clearly measurable in oval cells. Similar enzyme activities were found in freshly isolated and cultured oval cells. The highest activities of these three enzymes were detected during the exponential growth phase of the cultured cells; thereafter the activities decreased until the cells reached confluency. Changes in phenol UDP-glucuronosyltransferase (UGT1A1) mRNA levels paralleled the variations in UDP-glucuronosyltransferase activity, i.e. they were high in exponentially growing oval cells and low in confluent cell cultures. Taking into account that oval cells are able to proliferate in the livers of rats continuously fed a choline-deficient/DL-ethionine-supplemented diet and that none of the analyzed drug metabolizing enzymes are involved in the activation or detoxication ofDL-ethionine, the described pattern might be part of a more general, nonspecific, protection mechanism enabling these cells to overcome the cytotoxic effects of a variety of carcinogens and to proliferate even in their presence. Furthermore, the expression of microsomal epoxide hydrolase, cytosolic glutathione transferase and UDP-glucuronosyltransferase appears to depend on the proliferative status of the cells.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00757187

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Synthesis and ring-opening polymerization of novel bicyclic oxalactams: 2-oxa-5-azabicyclo[2.2.2]octan-6-one (1990)

Okada, Masahiko ; Sumitomo, Hiroshi ; Mori, Hiroto ; [et al.]

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 3251-3260

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ISSN: 0887-624X

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A novel bicyclic oxalactam 2-oxa-5-azabicyclo [2.2.21 octan-6-one (2,5-BOL) was synthesized from sodium 3,4-dihydro-2H-pyran-2-carboxylate through a seven-step reaction sequence. Anionic ring-opening polymerization of 2,5-BOL was carried out in bulk at 12OOC or in dimethyl sulfoxide at 40, 60, and 80°C by using potassium pyrrolidonate and the N-benzoyl derivative of 2,5-BOL as catalyst and activator, respectively. The polymerization gave a new polyamide containing cis- and trans-2,5-linked tetrahydropyran rings in the main chain. The cis/trans ratio varied from 70/30 to 95 /5 depending on the reaction conditions. The polyamide having number average molecular weights of 3000-8000 was soluble in a variety of solvents including methanol, ethanol, dimethyl sulfoxide, dimethylformamide, chloroform, and dichloromethane. It began to decompose at 280-32OOC depending on the compositions of the cis- and trans-2,5-linked structural units. The anionic ring-opening polymerizability of 2,5-BOL was found to be much lower than its structural isomer, 8-oxa-6-azabicyclo[ 3.2.11 octan-7-one (8,6-BOL).

Additional Material: 3 Ill.