Assay of hepatic microsomal testosterone hydroxylases by high-performance liquid chromatography

Hoeven, Th. van der

doi:10.1016/0003-2697(84)90768-1

Cited by 71 publications

(21 citation statements)

References 19 publications

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“…The organic phase was extracted with 2 mL 0.02 N NaOH to remove lipid constituents, dried over anhydrous sodium sulphate and transferred to a small tube. Dichloromethane was evaporated at 37 • C under nitrogen and the dried samples stored at −20 • C. The samples were dissolved in 100 L methanol and analysed by HPLC [47].…”

Section: Testosterone Hydroxylase (Th)mentioning

confidence: 99%

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Modulation of cytochrome P450 and induction of DNA damage in Cyprinus carpio exposed in situ to surface water treated with chlorine or alternative disinfectants in different seasons

Canistro

Melega

Ranieri

et al. 2012

Mutation Research/Fundamental and Molecular Mechanisms of Mutag

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Epidemiological studies have shown an association between consumption of disinfected drinking water and adverse health outcomes. The chemicals used to disinfect water react with occurring organic matter and anthropogenic contaminants in the source water, resulting in the formation of disinfection byproducts (DBPs). The observations that some DBPs are carcinogenic in animal models have raised public concern over the possible adverse health effects for humans. Here, the modulation of liver cytochrome P450-linked monooxygenases (MFO) and the genotoxic effects in erythrocytes of Cyprinus carpio fish exposed in situ to surface drinking water in the presence of disinfectants, such as sodium hypochlorite (NaClO), chlorine dioxide (ClO 2 ) and peracetic acid (PAA), were investigated in winter and summer. A complex induction/suppression pattern of CYP-associated MFOs in winter was observed for all disinfectants. For example, a 3.4-to 15-fold increase was recorded of the CYP2B1/2-linked dealkylation of penthoxyresorufin with NaClO (10 days) and PAA (20 days). In contrast, ClO 2 generated the most notable inactivation, the CYP2E1-supported hydroxylation of p-nitrophenol being decreased up to 71% after 10 days' treatment. In summer, the degree of modulation was modest, with the exception of CYP3A1/2 and CYP1A1 supported MFOs (62% loss after 20 days PAA).The micronucleus (MN) induction in fish circulating erythrocytes was also analysed as an endpoint of genotoxic potential in the same fish population. Significant increases of MN induction were detected at the latest sampling time on fish exposed to surface water treated with chlorinate-disinfectants, both in winter (NaClO) and summer (NaClO and ClO 2 ), while no effect was observed in fish exposed to PAA-treated water.These results show that water disinfection may be responsible for harmful outcomes in terms of MFO perturbation and DNA damage; if extrapolated to humans, they ultimately offer a possible rationale for the increased urinary cancer risk recorded in regular drinking water consumers.

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Section: Testosterone Hydroxylase (Th)mentioning

confidence: 99%

“…The eluent was monitored at 254 nm and the area under the absorption band was integrated. The concentration of metabolites was determined by the ratio between respective metabolite peak areas and corticosterone (the internal standard), and the calibration curves were obtained with synthetic testosterone derivatives [47].…”

Section: Testosterone Hydroxylase (Th)mentioning

confidence: 99%

Modulation of cytochrome P450 and induction of DNA damage in Cyprinus carpio exposed in situ to surface water treated with chlorine or alternative disinfectants in different seasons

Canistro

Melega

Ranieri

et al. 2012

Mutation Research/Fundamental and Molecular Mechanisms of Mutag

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show abstract

Section: Testosterone Hydroxylase (Th)mentioning

confidence: 99%

Perturbation of cytochrome P450, generation of oxidative stress and induction of DNA damage in Cyprinus carpio exposed in situ to potable surface water

Sapone¹,

Gustavino²,

Monfrinotti³

et al. 2007

Mutation Research/Genetic Toxicology and Environmental Mutagene

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Epidemiological evidence suggests a link between consumption of chlorinated drinking water and various cancers. Chlorination of water rich in organic chemicals produces carcinogenic organochlorine by-products (OBPs) such as trihalomethanes and haloacetic acids. Since the discovery of the first OBP in the 1970s, there have been several investigations designed to determine the biological effects of single chemicals or small artificial OBP combinations. However, there is still insufficient information regarding the general biological response to these compounds, and further studies are still needed to evaluate their potential genotoxic effects. In the current study, we evaluated the effect of three drinking water disinfectants on the activity of cytochrome P450 (CYP)-linked metabolizing enzymes and on the generation of oxidative stress in the livers of male and female Cyprinus carpio fish (carp). The fish were exposed in situ for up 20 days to surface water obtained from the Trasmene lake in Italy. The water was treated with 1-2 mg/L of either sodium hypochlorite (NaClO) or chlorine dioxide (ClO 2 ) as traditional disinfectants or with a relatively new disinfectant product, peracetic acid (PAA). Micronucleus (MN) frequencies in circulating erythrocytes from the fish were also analysed as a biomarker of genotoxic effect. In the CYP-linked enzyme assays, a significant induction (up to a 57-fold increase in the deethylation of ethoxyresorufin with PAA treatment) and a notable inactivation (up to almost a 90% loss in hydroxylation of p-nitrophenol with all disinfectants, and of testosterone 2␤-hydroxylation with NaClO) was observed in subcellular liver preparations from exposed fish. Using the electron paramagnetic resonance (EPR) spectroscopy radical-probe technique, we also observed that CYP-modulation was associated with the production of reactive oxygen species (ROS). In addition, we found a significant increase in MN frequency in circulating erythrocytes after 10 days of exposure of fish to water treated with ClO 2 , while a non-significant six-fold increase in MN frequency was observed with NaClO, but not with PAA. Our data suggest that the use of ClO 2 and NaClO to disinfect drinking water could generate harmful OBP mixtures that are able to perturb CYP-mediated reactions, generate oxidative stress and induce Abbreviations: NaClO, sodium hypochlorite; ClO 2 , chlorine dioxide; PAA, peracetic acid; CYP, cytochrome P450; MN, micronuclei; OBPs, organochlorine by-products; ROS, reactive oxygen species * Corresponding author. . Sapone et al. / Mutation Research 626 (2007) 143-154 genetic damage. These data may provide a mechanistic explanation for epidemiological studies linking consumption of chlorinated drinking water to increased risk of urinary, gastrointestinal and bladder cancers.

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“…terone, 2 mg), 6b-hydroxytestosterone formation was quantQuantitative enzyme kinetic inhibition studies revealed ified following extraction by h.p.l.c. analysis according to a that the mean apparent K i for sertraline, fluvoxamine, published procedure [31].…”

Section: Hplc Analysis Of 2-hydroxyimipramine 2-hydroxy-mentioning

confidence: 99%

Venlafaxine: in vitro inhibition of CYP2D6 dependent imipramine and desipramine metabolism; comparative studies with selected SSRIs, and effects on human hepatic CYP3A4, CYP2C9 and CYP1A2

Ball

Ahern

Scatina

et al. 1997

Brit J Clinical Pharma

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Aims In order to anticipate drug-interactions of potential clinical significance the ability of the novel antidepressant, venlafaxine, to inhibit CYP2D6 dependent imipramine and desipramine 2-hydroxylation was investigated in human liver microsomes. The data obtained were compared with the selective serotonin re-uptake inhibitors, fluoxetine, sertraline, fluvoxamine and paroxetine. Venlafaxine's potential to inhibit several other major P450s was also studied (CYP3A4, CYP2D6, CYP1A2). Methods K i values for venlafaxine, paroxetine, fluoxetine, fluvoxamine and sertraline as inhibitors of imipramine and desipramine 2-hydroxylation were determined from Dixon plots of control and inhibited rate data in human hepatic microsomal incubations. The inhibitory effect of imipramine and desipramine on liver microsomal CYP2D6 dependent venlafaxine O-demethylation was determined similarly. Venlafaxine's IC 50 values for CYP3A4, CYP1A2 CYP2C9 were determined based on inhibition of probe substrate activities (testosterone 6b-hydroxylation, ethoxyresorufin O-dealkylase and tolbutamide 4-hydroxylation, respectively). Results Fluoxetine, paroxetine, and fluvoxamine were potent inhibitors of imipramine 2-hydroxylase activity (K i values of 1.6±0.8, 3.2±0.8 and 8.0±4.3 mm, respectively; mean±s.d., n=3), while sertraline was less inhibitory (K i of 24.7±8.9 mm). Fluoxetine also markedly inhibited desipramine 2-hydroxylation with a K i of 1.3±0.5 mm. Venlafaxine was less potent an inhibitor of imipramine 2-hydroxylation (K i of 41.0±9.5 mm) than the SSRIs that were studied. Imipramine and desipramine gave marked inhibition of CYP2D6 dependent venlafaxine O-demethylase activity (K i values of 3.9±1.7 and 1.7±0.9 mm, respectively). Venlafaxine did not inhibit ethoxyresorufin O-dealkylase (CYP1A2), tolbutamide 4-hydroxylase (CYP2C9) or testosterone 6b-hydroxylase (CYP3A4) activities at concentrations of up to 1 mm. Conclusions It is concluded that venlafaxine has a low potential to inhibit the metabolism of substrates for CYP2D6 such as imipramine and desipramine compared with several of the most widely used SSRIs, as well as the metabolism of substrates for several of the other major human hepatic P450s.

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Assay of hepatic microsomal testosterone hydroxylases by high-performance liquid chromatography

Cited by 71 publications

References 19 publications

Modulation of cytochrome P450 and induction of DNA damage in Cyprinus carpio exposed in situ to surface water treated with chlorine or alternative disinfectants in different seasons

Modulation of cytochrome P450 and induction of DNA damage in Cyprinus carpio exposed in situ to surface water treated with chlorine or alternative disinfectants in different seasons

Perturbation of cytochrome P450, generation of oxidative stress and induction of DNA damage in Cyprinus carpio exposed in situ to potable surface water

Venlafaxine: in vitro inhibition of CYP2D6 dependent imipramine and desipramine metabolism; comparative studies with selected SSRIs, and effects on human hepatic CYP3A4, CYP2C9 and CYP1A2

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