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- Canaparo, Roberto, et al.
(author)
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Expression of cytochromes P450 3A and P-glycoprotein in human large intestine in paired tumour and normal samples
- 2007
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In: Basic & Clinical Pharmacology & Toxicology. - : Wiley. - 1742-7843 .- 1742-7835. ; 100:4, s. 240-248
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Journal article (peer-reviewed)abstract
- Our objective was to investigate the expression of different cytochromes P450 3A (CYP3A4, CYP3A5, and CYP3A7) and P-glycoprotein (ABCBI) genes along the human large intestine in paired tumour and normal samples. Real-time reverse transcriptase-polymerase chain reaction was used to measure CYP3A4-, CYP3A5-, CYP3A7- and ABCB1-specific mRNA expression, and Western blot analysis was used to measure membrane protein levels of CYP3A4/7, CYP3A5 and P-glycoprotein. Levels of mRNA and membrane protein fractions in the large intestine were compared with those of normal human liver. The mRNA expressions of CYP3A4, CYP3A5, CYP3A7 and ABCB1 in the large intestine were found to be highly variable, but overall the levels were significantly lower than those measured in liver (P < 0.0001, P < 0.00 1, P < 0.0001 and P < 0.01, respectively). At the membrane protein level, CYP3A4/7 was detected in all large intestine samples examined and the levels were substantially higher than those of the liver (P < 0.01). Although expression of CYP3A5 was detected in all large intestine samples, in most the levels were too low to allow quantification. P-glycoprotein was readily detected at levels slightly higher than those of liver (P < 0.05). Comparison between paired samples of normal and tumour in large intestine showed no significant differences in either the mRNA or membrane protein levels of these genes. In conclusion, this work suggests a potential role of the large intestine in the absorption and metabolism of xenobiotics and nutrients and no difference in the CYP3A and P-glycoprotein membrane protein fractions and mRNA expression between normal and tumour tissues.
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2. |
- Tuvesson, Helen, et al.
(author)
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In vitro metabolism and in vivo pharmacokinetics of quinoline 3-carboxamide derivatives in various species
- 2005
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In: Xenobiotica. - : Informa UK Limited. - 0049-8254 .- 1366-5928. ; 35:3, s. 293-304
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Journal article (peer-reviewed)abstract
- The metabolism of a group of quinoline 3-carboxamide derivatives was evaluated in liver microsomes from various species. In addition, metabolism data were compared with in vivo pharmacokinetics in the mouse. The studied compounds were metabolized by cytochrome P450 enzymes. Microsomal clearance was low and seemed independent of a substituent in the quinoline moiety, whereas clearance was enhanced when an ethyl group replaced the methyl group at the carboxamide position. A similar metabolism with hydroxylated and dealkylated metabolites was found in the various species, with quantitative differences due to substituent. As predicted from the in vitro studies, in vivo pharmacokinetics showed low clearance and thus high exposure of the parent compounds in the mouse. The therapeutic effect seen in the acute EAE mouse model for these related compounds seems dependent on the high exposure of parent compound rather than formation of any potentially active metabolites.
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