101
|
Hashimoto M, Kobayashi K, Watanabe M, Kazuki Y, Takehara S, Inaba A, Nitta SI, Senda N, Oshimura M, Chiba K. Knockout of mouse Cyp3a gene enhances synthesis of cholesterol and bile acid in the liver. J Lipid Res 2013; 54:2060-2068. [PMID: 23709690 DOI: 10.1194/jlr.m033464] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Here, we studied the effects of cytochrome P450 (CYP)3A deficiency on the mRNA expression of genes encoding regulators of hepatic cholesterol levels using Cyp3a-knockout (Cyp3a(-/-)) mice. The mRNA expression levels of genes encoding enzymes involved in cholesterol biosynthesis in the livers of Cyp3a(-/-) mice were higher than those of wild-type (WT) mice. Nuclear levels of sterol regulatory element-binding protein-2 (SREBP-2), which enhances cholesterol biosynthesis, were also higher in the livers of Cyp3a(-/-) mice. Binding of SREBP-2 to the Hmgcs1 gene promoter was more abundant in the livers of Cyp3a(-/-) mice. These results suggest that deficiency of CYP3A enzymes enhances transcription of genes encoding enzymes involved in cholesterol biosynthesis via activation of SREBP-2. On the other hand, hepatic cholesterol levels in Cyp3a(-/-) mice were 20% lower than those in WT mice. The mRNA expression levels of genes encoding enzymes involved in bile acid synthesis, plasma levels of 7α-hydroxy-4-cholesten-3-one and hepatic levels of total bile acid were significantly higher in Cyp3a(-/-) mice than in WT mice. These findings suggest that reduction of hepatic total cholesterol in Cyp3a(-/-) mice would be the consequence of enhanced bile acid synthesis. Therefore, CYP3A enzymes appear to play roles in the synthesis of cholesterol and bile acid in vivo.
Collapse
Affiliation(s)
- Mari Hashimoto
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Kaoru Kobayashi
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Mio Watanabe
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Yasuhiro Kazuki
- Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Tottori 683-8503, Japan; Chromosome Engineering Research Center (CERC), Tottori University, Tottori 683-8503, Japan
| | - Shoko Takehara
- Chromosome Engineering Research Center (CERC), Tottori University, Tottori 683-8503, Japan
| | - Asumi Inaba
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Shin-Ichiro Nitta
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan; Mitsubishi Chemical Medience Corporation, Ibaraki 305-0047, Japan
| | - Naoto Senda
- Mitsubishi Chemical Medience Corporation, Ibaraki 305-0047, Japan
| | - Mitsuo Oshimura
- Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Tottori 683-8503, Japan; Chromosome Engineering Research Center (CERC), Tottori University, Tottori 683-8503, Japan
| | - Kan Chiba
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| |
Collapse
|
102
|
Björkhem-Bergman L, Bäckström T, Nylén H, Rönquist-Nii Y, Bredberg E, Andersson TB, Bertilsson L, Diczfalusy U. Comparison of Endogenous 4β-Hydroxycholesterol with Midazolam as Markers for CYP3A4 Induction by Rifampicin. Drug Metab Dispos 2013; 41:1488-93. [DOI: 10.1124/dmd.113.052316] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
|
103
|
Sodhi RK, Singh N. Liver X receptors: emerging therapeutic targets for Alzheimer's disease. Pharmacol Res 2013; 72:45-51. [PMID: 23542729 DOI: 10.1016/j.phrs.2013.03.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 03/11/2013] [Accepted: 03/21/2013] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD) is a complex neurodegenerative disorder, typified by the pathological accumulation of ß-amyloid peptides (Aß) and neurofibrillary tangles within the brain, culminating to cognitive impairment. Epidemiological and biochemical data have suggested a link between cholesterol content, APP (amyloid precursor protein) processing, Aß, inflammation and AD. The intricacy of the disease presents considerable challenges for the development of newer therapeutic agents. Liver X receptors (LXRa and LXRß) are oxysterol activated nuclear receptors that play essential role in lipid and glucose homeostasis, steroidogenesis and inflammatory responses. LXR signalling impacts the development of AD pathology through multiple pathways. Reports indicate that genetic loss of either lxra or lxrß in APP/PS1 transgenic mice results in increased amyloid plaque load. Studies also suggest that ligand activation of LXRs in Tg2576 mice enhanced, the expression of genes linked with cholesterol efflux e.g. apoe, abca-1, down regulated APP processing and Aß production with significant improvement in memory functions. LXR agonists have also depicted to inhibit neuroinflammation through modulation of microglial phagocytosis and by repressing the expression of cox2, mcp1 and iNos in glial cells. This review summarizes in brief the biology of LXRs, with an emphasis on their probable pathophysiological mechanisms that may elicit the defending role of these receptors in brains of AD patients.
Collapse
Affiliation(s)
- Rupinder K Sodhi
- Pharmacology Division, Department of Pharmaceutical Sciences and Drug Research, Faculty of Medicine, Punjabi University, Patiala 147002, Punjab, India
| | | |
Collapse
|
104
|
Interrelationship between ATP-binding cassette transporters and oxysterols. Biochem Pharmacol 2013; 86:80-8. [PMID: 23500544 DOI: 10.1016/j.bcp.2013.02.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 02/27/2013] [Accepted: 02/27/2013] [Indexed: 12/11/2022]
Abstract
ATP-binding cassette (ABC) transporters constitute a ubiquitous superfamily of membrane proteins responsible for the translocation of several substances across membranes using the chemical energy provided by ATP hydrolysis. ABC transporters participate in many physiological and pathophysiological processes, including cholesterol and lipid transportation and multidrug resistance. Oxysterols are the products of cholesterol oxidation, formed by both enzymatic and non-enzymatic mechanisms. The role of oxysterols in cholesterol metabolism and several diseases has been widely investigated, but many questions remain to be answered. Several lines of evidence link ABC transporter functions with cholesterol and oxysterol metabolism. This review discusses ABC transporters, oxysterols, and how they interact with each other.
Collapse
|
105
|
Yang Z, Rodrigues AD. Does the Long Plasma Half-Life of 4β-Hydroxycholesterol Impact Its Utility as a Cytochrome P450 3A (CYP3A) Metric? J Clin Pharmacol 2013; 50:1330-8. [DOI: 10.1177/0091270009360041] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
106
|
Biological activities of the LXRα and β agonist, 4β-hydroxycholesterol, and of its isomer, 4α-hydroxycholesterol, on oligodendrocytes: Effects on cell growth and viability, oxidative and inflammatory status. Biochimie 2013; 95:518-30. [DOI: 10.1016/j.biochi.2012.11.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 11/15/2012] [Indexed: 12/15/2022]
|
107
|
On the formation and possible biological role of 25-hydroxycholesterol. Biochimie 2013; 95:455-60. [DOI: 10.1016/j.biochi.2012.06.016] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 06/14/2012] [Indexed: 11/22/2022]
|
108
|
Methods for oxysterol analysis: past, present and future. Biochem Pharmacol 2013; 86:3-14. [PMID: 23395696 DOI: 10.1016/j.bcp.2013.01.027] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 01/28/2013] [Indexed: 12/20/2022]
Abstract
Oxysterols are oxidised forms of cholesterol or its precursors. In this article we will concentrate specifically on those formed in mammalian systems. Oxidation may be catalysed by endogenous enzymes or through reactive oxygen species forming a myriad of potential products. A number of these products are biologically active, and oxysterols may have roles in cholesterol homeostasis, neurogenesis, protein prenylation and in the immune system. Oxysterols are also implicated in aetiology of disease states including atherosclerosis, neurodegenerative and inflammatory diseases. Reports indicating the levels of oxysterols in plasma, cerebrospinal fluid and various tissues are in many cases unrealistic owing to a lack of attention to the possibility of autoxidation, a process by which oxysterols are formed from cholesterol by oxygen in air. This article comprises a critical assessment of the technical difficulties of oxysterol analysis, highlights methodologies utilising best practise and discusses newer procedures.
Collapse
|
109
|
Björkhem-Bergman L, Nylén H, Norlin AC, Lindh JD, Ekström L, Eliasson E, Bergman P, Diczfalusy U. Serum levels of 25-hydroxyvitamin D and the CYP3A biomarker 4β-hydroxycholesterol in a high-dose vitamin D supplementation study. Drug Metab Dispos 2013; 41:704-8. [PMID: 23386704 DOI: 10.1124/dmd.113.051136] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The primary aim was to study the relationship between individual serum levels of 25-hydroxyvitamin D and 4β-hydroxycholesterol, which is an endogenous biomarker of the drug-metabolizing CYP3A enzymes. In addition, the relationship between this biomarker and inflammation, measured as C-reactive protein (CRP), was investigated. Serum samples were used from a recently performed clinical trial in patients with antibody deficiency or increased susceptibility to respiratory tract infections that were randomized to either placebo or high-dose (4000 IU/day) vitamin D for 12 months. One hundred sixteen patients were included in the final analyses, and serum samples collected 6 months after study start were analyzed. At this time point, 25-hydroxyvitamin D levels were found to range between 10 and 284 nM. Individual levels of 25-hydroxyvitamin D as well as CRP were compared with 4β-hydroxycholesterol levels. In addition, all participants were genotyped for two polymorphisms (Taq1 and Foq1) in the vitamin D receptor gene. There was no significant correlation between individual serum levels of 25-hydroxyvitamin D and 4β-hydroxycholesterol. However, a moderate, but statistically significant, negative correlation between CRP and 4β-hydroxycholesterol levels was observed. This study in patients with highly variable serum levels of 25-hydroxyvitamin D could not reveal any relationship between vitamin D and 4β-hydroxycholesterol, an endogenous biomarker of CYP3A activity. However, the negative correlation between CRP and 4β-hydroxycholesterol supports earlier experimental results that inflammation may suppress hepatic CYP3A activity, a finding of potentially high clinical relevance that warrants further exploration.
Collapse
Affiliation(s)
- Linda Björkhem-Bergman
- Karolinska Institutet, Department of Laboratory Medicine, Divisions of Clinical Pharmacology, Stockholm, Sweden.
| | | | | | | | | | | | | | | |
Collapse
|
110
|
Xu L, Korade Z, Rosado DA, Mirnics K, Porter NA. Metabolism of oxysterols derived from nonenzymatic oxidation of 7-dehydrocholesterol in cells. J Lipid Res 2013; 54:1135-43. [PMID: 23381570 DOI: 10.1194/jlr.m035733] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Recent studies suggest that 7-dehydrocholesterol (7-DHC)-derived oxysterols play important roles in the pathophysiology of Smith-Lemli-Opitz syndrome (SLOS), a metabolic disorder that is caused by defective 3β-hydroxysterol-Δ(7)-reductase (DHCR7). Although 14 oxysterols have been identified as the primary products of 7-DHC autoxidation in organic solution, the metabolic fate of these oxysterols in a biological environment has not yet been elucidated. Therefore, we incubated these primary 7-DHC oxysterols in control Neuro2a and control human fibroblast cells and identified metabolites of these oxysterols by HPLC-MS. We also incubated Dhcr7-deficient Neuro2a cells and fibroblasts from SLOS patients with isotopically labeled 7-DHC (d(7)-7-DHC). The observation of matching d(0)- and d(7) peaks in HPLC-MS confirmed the presence of true metabolites of 7-DHC after excluding the possibility of ex vivo oxidation. The metabolites of primary 7-DHC oxysterols were found to contribute to the majority of the metabolic profile of 7-DHC in cells. Furthermore, based on this new data, we identified three new 7-DHC-derived metabolites in the brain of Dhcr7-KO mice. Our studies suggest that 7-DHC peroxidation is a major source of oxysterols observed in cells and in vivo and that the stable metabolites of primary 7-DHC oxysterols can be used as markers of 7-DHC peroxidation in these biological systems.
Collapse
Affiliation(s)
- Libin Xu
- Department of Chemistry and Vanderbilt Institute of Chemical Biology and, Vanderbilt University, Nashville, TN 37235, USA.
| | | | | | | | | |
Collapse
|
111
|
Korade Z, Xu L, Mirnics K, Porter NA. Lipid biomarkers of oxidative stress in a genetic mouse model of Smith-Lemli-Opitz syndrome. J Inherit Metab Dis 2013; 36:113-22. [PMID: 22718275 PMCID: PMC3674764 DOI: 10.1007/s10545-012-9504-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 05/09/2012] [Accepted: 05/20/2012] [Indexed: 02/01/2023]
Abstract
7-Dehydrocholesterol (7-DHC) accumulates in tissues and fluids of patients with Smith-Lemli-Opitz syndrome (SLOS), which is caused by mutations in the gene encoding 3β-hydroxysterol-Δ(7)-reductase (DHCR7). We recently reported that 7-DHC is the most reactive lipid molecule toward free radical oxidation (lipid peroxidation) and 14 oxysterols have been identified as products of oxidation of 7-DHC in solution. As the high oxidizability of 7-DHC may lead to systemic oxidative stress in SLOS patients, we report here lipid biomarkers of oxidative stress in a Dhcr7-KO mouse model of SLOS, including oxysterols, isoprostanes (IsoPs), and neuroprostanes (NeuroPs) that are formed from the oxidation of 7-DHC, arachidonic acid and docosahexaenoic acid, respectively. In addition to a previously described oxysterol, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), we provide evidence for the chemical structures of three new oxysterols in the brain and/or liver tissue of Dhcr7-KO mice, two of which were quantified. We find that levels of IsoPs and NeuroPs are also elevated in brain and/or liver tissues of Dhcr7-KO mice relative to matching WT mice. While IsoPs and NeuroPs have been established as a reliable measurement of lipid peroxidation and oxidative stress in vivo, we show that in this genetic SLOS mouse model, 7-DHC-derived oxysterols are present at much higher levels than IsoPs and NeuroPs and thus are better markers of lipid oxidation and related oxidative stress.
Collapse
Affiliation(s)
- Zeljka Korade
- Department of Psychiatry and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37235, USA
| | - Libin Xu
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Nashville, TN 37235, USA
| | - Karoly Mirnics
- Department of Psychiatry and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37235, USA
| | - Ned A. Porter
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Nashville, TN 37235, USA. Department of Chemistry, 7962 Stevenson Center, Vanderbilt University, Nashville, TN 37235, USA
| |
Collapse
|
112
|
Habtewold A, Amogne W, Makonnen E, Yimer G, Nylén H, Riedel KD, Aderaye G, Bertilsson L, Burhenne J, Diczfalusy U, Aklillu E. Pharmacogenetic and pharmacokinetic aspects of CYP3A induction by efavirenz in HIV patients. THE PHARMACOGENOMICS JOURNAL 2012; 13:484-9. [PMID: 23089673 DOI: 10.1038/tpj.2012.46] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 08/28/2012] [Accepted: 09/05/2012] [Indexed: 01/10/2023]
Abstract
We investigated the effects of pharmacogenetic variations and efavirenz pharmacokinetics on inter-individual differences in the extent of CYP3A induction by efavirenz using 4β-hydroxycholesterol/cholesterol (4β-OHC/Chol) as a marker for CYP3A induction. Plasma 4β-hydroxycholesterol and cholesterol concentrations were determined at baseline, and at the 4th, 16th and 48th week of efavirenz-based highly active antiretroviral therapy in antiretroviral therapy-naive HIV patients (n=77). Efavirenz plasma concentrations were quantified at weeks 4 and 16. CYP2B6, CYP3A5, ABCB1, UGT2B7 genotyping were done. Compared with baseline, the median plasma 4β-OHC/Chol ratio increased at the 4th (257%), 16th (291%) and 48th (165%) week (P<0.0001). CYP2B6*6 genotype significantly influenced 4β-OHC/Chol ratio at weeks 16 (P=0.02) and 48 (P=0.04) being highest in CYP2B6*6/*6>*1/*6>*1/*1. There were positive correlations between plasma efavirenz and 4β-OHC/Chol ratios (week 4: P=0.02, week 16: P=0.001). CYP3A enzyme induction by efavirenz is pronounced in CYP2B6 slow metabolizers who have high efavirenz plasma exposure.
Collapse
Affiliation(s)
- A Habtewold
- 1] Division of Clinical Pharmacology, Department of Laboratory of Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge C1-68, Stockholm, Sweden [2] Department of Pharmacology, Medical Faculty, Addis Ababa University, Addis Ababa, Ethiopia
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
113
|
Meaney S. Epigenetic regulation of oxysterol formation. Biochimie 2012; 95:531-7. [PMID: 22986023 DOI: 10.1016/j.biochi.2012.08.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 08/31/2012] [Indexed: 11/26/2022]
Abstract
Oxysterols are oxygenated derivatives of cholesterol that may be formed by either enzymatic or non-enzymatic mechanisms. Expression of the genes responsible for oxysterol synthesis (GROS) is known to be restricted across different tissues and cell types. Regulation of the transcription of GROS and the activity of their enzyme transcripts has been the subject of intense activity for many years. Recent studies have sought to decipher the mechanism(s) that underpin the restricted expression of the GROS. Available data indicates that epigenetic mechanisms have an important role to play in the control of the expression of GROS. In the current review we summarize the available evidence for the epigenetic regulation of these genes.
Collapse
Affiliation(s)
- Steve Meaney
- School of Biological Sciences, College of Sciences and Health, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland.
| |
Collapse
|
114
|
Oxidation with selenium dioxide: the first report of solvent-selective steroidal aromatization, efficient access to 4β,7α-dihydroxy steroids, and syntheses of natural diaromatic ergosterols. Tetrahedron 2012. [DOI: 10.1016/j.tet.2012.05.110] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
115
|
Kamal MA, Raghunathan VA. Effect of ring-substituted oxysterols on the phase behavior of dipalmitoylphosphatidylcholine membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 41:891-900. [DOI: 10.1007/s00249-012-0823-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 05/02/2012] [Accepted: 05/07/2012] [Indexed: 12/12/2022]
|
116
|
|
117
|
Xu L, Sheflin LG, Porter NA, Fliesler SJ. 7-Dehydrocholesterol-derived oxysterols and retinal degeneration in a rat model of Smith-Lemli-Opitz syndrome. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:877-83. [PMID: 22425966 DOI: 10.1016/j.bbalip.2012.03.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 02/17/2012] [Accepted: 03/02/2012] [Indexed: 01/08/2023]
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is a recessive disease characterized by markedly elevated levels of 7-dehydrocholesterol (7-DHC) and reduced levels of cholesterol in tissues and fluids of affected individuals, due to defective 3β-hydroxysterol-Δ(7)-reductase (Dhcr7). Treatment of Sprague Dawley rats with AY9944 (an inhibitor of Dhcr7) leads to similar biochemical features as observed in SLOS. Eighteen oxysterols previously have been identified as oxidation products of 7-DHC (most of them distinct from cholesterol (Chol)-derived oxysterols) in solution, in cells, and in brains obtained from Dhcr7-KO mice and AY9944-treated rats, formed either via free radical oxidation (peroxidation) or P450-catalyzed enzymatic oxidation. We report here the identification of five 7-DHC-derived oxysterols, including 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), 4α- and 4β-hydroxy-7-DHC, 24-hydroxy-7-DHC and 7-ketocholesterol (7-kChol, an oxysterol that is normally derived from Chol), in the retinas of AY9944-treated rats by comparing the retention times and mass spectrometric characteristics with corresponding synthetic standards in HPLC-MS analysis. Levels of 4α- and 4β-hydroxy-7-DHC, DHCEO, and 7-kChol were quantified using d(7)-DHCEO as an internal standard. Among the five oxysterols identified, only 7-kChol was observed in retinas of control rats, but the levels of 7-kChol in retinas of AY9944-rats were 30-fold higher. Intravitreal injection of 7-kChol (0.25μmol) into a normal rat eye induced panretinal degeneration within one week; by comparison, contralateral (control) eyes injected with vehicle alone exhibited normal histology. These findings are discussed in the context of the potential involvement of 7-DHC-derived oxysterols in the retinal degeneration associated with the SLOS rat model and in SLOS patients.
Collapse
Affiliation(s)
- Libin Xu
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
| | | | | | | |
Collapse
|
118
|
Metabolism of alprazolam (a marker of CYP3A4) in hemodialysis patients with persistent inflammation. Eur J Clin Pharmacol 2011; 68:571-7. [DOI: 10.1007/s00228-011-1163-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2011] [Accepted: 10/31/2011] [Indexed: 01/23/2023]
|
119
|
Turley WA, Burrell RC, Bonacorsi SJ, Goodenough AK, Onorato JM. Synthesis of [D4]- and [D7]-4β-hydroxycholesterols for use in a novel drug-drug interaction assay. J Labelled Comp Radiopharm 2011. [DOI: 10.1002/jlcr.1952] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Wesley A. Turley
- Radiochemical Synthesis Group; Bristol-Myers Squibb Research and Development; 5 Research Parkway; Wallingford; CT; 06492; USA
| | - Richard C. Burrell
- Radiochemical Synthesis Group; Bristol-Myers Squibb Research and Development; 5 Research Parkway; Wallingford; CT; 06492; USA
| | - Samuel J. Bonacorsi
- Radiochemical Synthesis Group; Bristol-Myers Squibb Research and Development; Route 206 and Province Line Road; Princeton; NJ; 08543; USA
| | - Angela K. Goodenough
- Department of Analytical and Discovery Analytical Sciences; Bristol-Myers Squibb Research and Development; Route 206 and Province Line Road; Princeton; NJ; 08543; USA
| | - Joelle M. Onorato
- Department of Analytical and Discovery Analytical Sciences; Bristol-Myers Squibb Research and Development; 311 Pennington and Rocky Hill Road; Pennington; NJ; 08534; USA
| |
Collapse
|
120
|
|
121
|
Shinkyo R, Xu L, Tallman KA, Cheng Q, Porter NA, Guengerich FP. Conversion of 7-dehydrocholesterol to 7-ketocholesterol is catalyzed by human cytochrome P450 7A1 and occurs by direct oxidation without an epoxide intermediate. J Biol Chem 2011; 286:33021-8. [PMID: 21813643 PMCID: PMC3190903 DOI: 10.1074/jbc.m111.282434] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 08/01/2011] [Indexed: 11/06/2022] Open
Abstract
7-Ketocholesterol is a bioactive sterol, a potent competitive inhibitor of cytochrome P450 7A1, and toxic in liver cells. Multiple origins of this compound have been identified, with cholesterol being the presumed precursor. Although routes for formation of the 7-keto compound from cholesterol have been established, we found that 7-dehydrocholesterol (the immediate precursor of cholesterol) is oxidized by P450 7A1 to 7-ketocholesterol (k(cat)/K(m) = 3 × 10(4) m(-1) s(-1)). P450 7A1 converted lathosterol (Δ(5)-dihydro-7-dehydrocholesterol) to a mixture of the 7-keto and 7α,8α-epoxide products (~1:2 ratio), with the epoxide not rearranging to the ketone. The oxidation of 7-dehydrocholesterol occured with predominant formation of 7-ketocholesterol and with the 7α,8α-epoxide as only a minor product; the synthesized epoxide was stable in the presence of P450 7A1. The mechanism of 7-dehydrocholesterol oxidation to 7-ketocholesterol is proposed to involve a Fe(III)-O-C-C(+) intermediate and a 7,8-hydride shift or an alternative closing to yield the epoxide (Liebler, D. C., and Guengerich, F. P. (1983) Biochemistry 22, 5482-5489). Accordingly, reaction of P450 7A1 with 7-[(2)H(1)]dehydrocholesterol yielded complete migration of deuterium in the product 7-ketocholesterol. The finding that 7-dehydrocholesterol is a precursor of 7-ketocholesterol has relevance to an inborn error of metabolism known as Smith-Lemli-Opitz syndrome (SLOS) caused by defective cholesterol biosynthesis. Mutations within the gene encoding 7-dehydrocholesterol reductase, the last enzyme in the pathway, lead to the accumulation of 7-dehydrocholesterol in tissues and fluids of SLOS patients. Our findings suggest that 7-ketocholesterol levels may also be elevated in SLOS tissue and fluids as a result of P450 7A1 oxidation of 7-dehydrocholesterol.
Collapse
Affiliation(s)
| | | | | | - Qian Cheng
- To whom correspondence should be addressed: Dept. of Biochemistry, Vanderbilt University School of Medicine, 638 Robinson Research Bldg., 2200 Pierce Ave., Nashville, TN 37232-0146. Tel.: 615-322-2261; Fax: 615-322-3141; E-mail:
| | - Ned A. Porter
- From the Departments of Biochemistry and
- Chemistry and
- Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - F. Peter Guengerich
- From the Departments of Biochemistry and
- Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| |
Collapse
|
122
|
Carvalho JFS, Silva MMC, Moreira JN, Simões S, Sá e Melo ML. Selective Cytotoxicity of Oxysterols through Structural Modulation on Rings A and B. Synthesis, in Vitro Evaluation, and SAR. J Med Chem 2011; 54:6375-93. [DOI: 10.1021/jm200803d] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- João F. S. Carvalho
- Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - M. Manuel Cruz Silva
- Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal
| | - João N. Moreira
- Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal
| | - Sérgio Simões
- Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal
| | - M. Luisa Sá e Melo
- Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal
| |
Collapse
|
123
|
Yin H, Xu L, Porter NA. Free Radical Lipid Peroxidation: Mechanisms and Analysis. Chem Rev 2011; 111:5944-72. [DOI: 10.1021/cr200084z] [Citation(s) in RCA: 1195] [Impact Index Per Article: 91.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Huiyong Yin
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Departments of Medicine and Pharmacology, Division of Clinical Pharmacology, Vanderbilt School of Medicine, Nashville, Tennessee 37232, United States
| | - Libin Xu
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Ned A. Porter
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| |
Collapse
|
124
|
Xu L, Liu W, Sheflin LG, Fliesler SJ, Porter NA. Novel oxysterols observed in tissues and fluids of AY9944-treated rats: a model for Smith-Lemli-Opitz syndrome. J Lipid Res 2011; 52:1810-20. [PMID: 21817059 DOI: 10.1194/jlr.m018366] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Treatment of Sprague-Dawley rats with AY9944, an inhibitor of 3β-hydroxysterol-Δ(7)-reductase (Dhcr7), leads to elevated levels of 7-dehydrocholesterol (7-DHC) and reduced levels of cholesterol in all biological tissues, mimicking the key biochemical hallmark of Smith-Lemli-Opitz syndrome (SLOS). Fourteen 7-DHC-derived oxysterols previously have been identified as products of free radical oxidation in vitro; one of these oxysterols, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), was recently identified in Dhcr7-deficient cells and in brain tissues of Dhcr7-null mouse. We report here the isolation and characterization of three novel 7-DHC-derived oxysterols (4α- and 4β-hydroxy-7-DHC and 24-hydroxy-7-DHC) in addition to DHCEO and 7-ketocholesterol (7-kChol) from the brain tissues of AY9944-treated rats. The identities of these five oxysterols were elucidated by HPLC-ultraviolet (UV), HPLC-MS, and 1D- and 2D-NMR. Quantification of 4α- and 4β-hydroxy-7-DHC, DHCEO, and 7-kChol in rat brain, liver, and serum were carried out by HPLC-MS using d(7)-DHCEO as an internal standard. With the exception of 7-kChol, these oxysterols were present only in tissues of AY9944-treated, but not control rats, and 7-kChol levels were markedly (>10-fold) higher in treated versus control rats. These findings are discussed in the context of the potential involvement of 7-DHC-derived oxysterols in the pathogenesis of SLOS.
Collapse
Affiliation(s)
- Libin Xu
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
| | | | | | | | | |
Collapse
|
125
|
Goodenough AK, Onorato JM, Ouyang Z, Chang S, Rodrigues AD, Kasichayanula S, Huang SP, Turley W, Burrell R, Bifano M, Jemal M, LaCreta F, Tymiak A, Wang-Iverson D. Quantification of 4-Beta-Hydroxycholesterol in Human Plasma Using Automated Sample Preparation and LC-ESI-MS/MS Analysis. Chem Res Toxicol 2011; 24:1575-85. [DOI: 10.1021/tx2001898] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Angela K. Goodenough
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Joelle M. Onorato
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Zheng Ouyang
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Shu Chang
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - A. David Rodrigues
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Sreeneeranj Kasichayanula
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Shu-Pang Huang
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Wesley Turley
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Richard Burrell
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Marc Bifano
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Mohammed Jemal
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Frank LaCreta
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - Adrienne Tymiak
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| | - David Wang-Iverson
- Departments of †Bioanalytical and Discovery Analytical Sciences, ‡Metabolism and Pharmacokinetics, §Discovery Medicine and Clinical Pharmacology, ∥Global Biometric Sciences, and ⊥Department of Chemical Synthesis, Research and Development, Bristol-Myers Squibb, Princeton, New Jersey 08543-4000, United States
| |
Collapse
|
126
|
van de Merbel NC, Bronsema KJ, van Hout MW, Nilsson R, Sillén H. A validated liquid chromatography–tandem mass spectrometry method for the quantitative determination of 4β-hydroxycholesterol in human plasma. J Pharm Biomed Anal 2011; 55:1089-95. [DOI: 10.1016/j.jpba.2011.03.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 03/10/2011] [Accepted: 03/11/2011] [Indexed: 11/25/2022]
|
127
|
Pathways of cholesterol oxidation via non-enzymatic mechanisms. Chem Phys Lipids 2011; 164:457-68. [PMID: 21703250 DOI: 10.1016/j.chemphyslip.2011.06.006] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 05/12/2011] [Accepted: 06/08/2011] [Indexed: 12/31/2022]
Abstract
Cholesterol has many functions, including those that affect biophysical properties of membranes, and is a precursor to hormone synthesis. These actions are governed by enzymatic pathways that modify the sterol nucleus or the isooctyl tail. The addition of oxygen to the cholesterol backbone produces its derivatives known as oxysterols. In addition to having an enzymatic origin, oxysterols can be formed in the absence of enzymatic catalysis in a pathway usually termed "autoxidation," which has been known for almost a century and observed under various experimental conditions. Autoxidation of cholesterol can occur through reactions initiated by free radical species, such as those arising from the superoxide/hydrogen peroxide/hydroxyl radical system and by non-radical highly reactive oxygen species such as singlet oxygen, HOCl, and ozone. The susceptibility of cholesterol to non-enzymatic oxidation has raised considerable interest in the function of oxysterols as biological effectors and potential biomarkers for the non-invasive study of oxidative stress in vivo.
Collapse
|
128
|
Diczfalusy U, Björkhem I. Still another activity by the highly promiscuous enzyme CYP3A4: 25-hydroxylation of cholesterol. J Lipid Res 2011; 52:1447-9. [PMID: 21652732 DOI: 10.1194/jlr.e017806] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Ulf Diczfalusy
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | | |
Collapse
|
129
|
Honda A, Miyazaki T, Ikegami T, Iwamoto J, Maeda T, Hirayama T, Saito Y, Teramoto T, Matsuzaki Y. Cholesterol 25-hydroxylation activity of CYP3A. J Lipid Res 2011; 52:1509-16. [PMID: 21576599 DOI: 10.1194/jlr.m014084] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To date, many studies have been conducted using 25-hydroxycholesterol, which is a potent regulator of lipid metabolism. However, the origins of this oxysterol have not been entirely elucidated. Cholesterol 25-hydroxylase is one of the enzymes responsible for the metabolism of 25-hydroxycholesterol, but the expression of this enzyme is very low in humans. This oxysterol is also synthesized by sterol 27-hydroxylase (CYP27A1) and cholesterol 24-hydroxylase(CYP46A1), but it is only a minor product of these enzymes. We now report that CYP3A synthesizes a significant amount of 25-hydroxycholesterol and may participate in the regulation of lipid metabolism. Induction of CYP3A by pregnenolone-16α-carbonitrile caused the accumulation of 25-hydroxycholesterol in a cell line derived from mouse liver. Furthermore, treatment of the cells with troleandomycin, a specific inhibitor of CYP3A, significantly reduced cellular 25-hydroxycholesterol concentrations. In cells that overexpressed human recombinant CYP3A4, the activity of cholesterol 25-hydroxylation was found to be higher than that of cholesterol 4β-hydroxylation, a known marker activity of CYP3A4. In addition, 25-hydroxycholesterol concentrations in normal human sera correlated positively with the levels of 4β-hydroxycholesterol (r = 0.650, P < 0.0001, n = 78), but did not significantly correlate with the levels of 27-hydroxycholesterol or 24S-hydroxycholesterol. These results demonstrate the significance of CYP3A on the production of 25-hydroxycholesterol.
Collapse
Affiliation(s)
- Akira Honda
- Department of Gastroenterology, Center for Collaborative Research, Ibaraki 300-0395, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
130
|
van Waterschoot RAB, Schinkel AH. A critical analysis of the interplay between cytochrome P450 3A and P-glycoprotein: recent insights from knockout and transgenic mice. Pharmacol Rev 2011; 63:390-410. [PMID: 21490128 DOI: 10.1124/pr.110.002584] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
CYP3A is one of the most important drug-metabolizing enzymes, determining the first-pass metabolism, oral bioavailability, and elimination of many drugs. It is also an important determinant of variable drug exposure and is involved in many drug-drug interactions. Recent studies with CYP3A knockout and transgenic mice have yielded a number of key insights that are important to consider during drug discovery and development. For instance, studies with tissue-specific CYP3A-transgenic mice have highlighted the importance of intestinal CYP3A-dependent metabolism. They also revealed that intestinal CYP3A plays an important role in the regulation of various drug-handling systems in the liver. Intestinal CYP3A activity can thus have far-reaching pharmacological effects. Besides CYP3A, the active drug efflux transporter P-glycoprotein also has a strong effect on the pharmacokinetics of numerous drugs. CYP3A and P-glycoprotein have an extensive overlap in their substrate spectrum. It has been hypothesized that for many drugs, the combined activity of CYP3A and P-glycoprotein makes for efficient intestinal first-pass metabolism of orally administered drugs as a result of a potentially synergistic collaboration. However, there is only limited in vitro and in vivo evidence for this hypothesis. There has also been some confusion in the field about what synergy actually means in this case. Our recent studies with Cyp3a/P-glycoprotein combination knockout mice have provided further insights into the CYP3A-P-glycoprotein interplay. We here present our view of the status of the synergy hypothesis and an attempt to clarify the existing confusion about synergy. We hope that this will facilitate further critical testing of the hypothesis and improve communication among researchers. Above all, the recent findings and insights into the interplay between CYP3A and P-glycoprotein may have implications for improving oral drug bioavailability and reducing adverse side effects.
Collapse
Affiliation(s)
- Robert A B van Waterschoot
- Division of Molecular Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | | |
Collapse
|
131
|
Shinkyo R, Guengerich FP. Inhibition of human cytochrome P450 3A4 by cholesterol. J Biol Chem 2011; 286:18426-33. [PMID: 21471209 DOI: 10.1074/jbc.m111.240457] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
If cholesterol is a substrate of P450 3A4, then it follows that it should also be an inhibitor, particularly in light of the high concentrations found in liver. Heme perturbation spectra indicated a K(d) value of 8 μM for the P450 3A4-cholesterol complex. Cholesterol inhibited the P450 3A4-catalyzed oxidations of nifedipine and quinidine, two prototypic substrates, in liver microsomes and a reconstituted enzyme system with K(i) ∼ 10 μM in an apparently non-competitive manner. The concentration of cholesterol could be elevated 4-6-fold in cultured human hepatocytes by incubation with cholesterol; the level of P450 3A4 and cell viability were not altered under the conditions used. Nifedipine oxidation was inhibited when the cholesterol level was increased. We conclude that cholesterol is both a substrate and an inhibitor of P450 3A4, and a model is presented to explain the kinetic behavior. We propose that the endogenous cholesterol in hepatocytes should be considered in models of prediction of metabolism of drugs and steroids, even in the absence of changes in the concentrations of free cholesterol.
Collapse
Affiliation(s)
- Raku Shinkyo
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
| | | |
Collapse
|
132
|
Diczfalusy U, Nylén H, Elander P, Bertilsson L. 4β-Hydroxycholesterol, an endogenous marker of CYP3A4/5 activity in humans. Br J Clin Pharmacol 2011; 71:183-9. [PMID: 21219398 DOI: 10.1111/j.1365-2125.2010.03773.x] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
We have proposed that 4β-hydroxycholesterol (4β-OHC) may be used as an endogenous marker of CYP3A activity. The cholesterol metabolite 4β-OHC is formed by CYP3A4. Treatment of patients with strong inducers of CYP3A enzymes, e.g. anti-epileptic drugs, resulted in 10-fold increased concentrations of plasma 4β-OHC, while treatment with CYP3A inhibitors such as ritonavir or itraconazole resulted in decreased plasma concentrations. There was a relationship between the 4β-OHC concentration and the number of active CYP3A5*1 alleles showing that 4β-OHC was not only formed by CYP3A4, but also by CYP3A5. The concentration of 4β-OHC was higher in women than in men, confirming previous studies indicating a gender difference in CYP3A4/5-activity. The rate of elimination of 4β-OHC is slow (half-life 17 days) which results in stable plasma concentrations within individuals, but limits its use to study rapid changes in CYP3A activity. In short-term studies exogenous markers such as midazolam or quinine may be superior, but in long-term studies 4β-OHC is a sensitive marker of CYP3A activity, especially to assess induction but also inhibition. Under conditions where the cholesterol concentration is changing, the ratio of 4β-OHC:cholesterol may be used as an alternative to 4β-OHC itself. The use of an endogenous CYP3A marker has obvious advantages and may be of value both during drug development and for monitoring CYP3A activity in patients.
Collapse
Affiliation(s)
- Ulf Diczfalusy
- Department of Laboratory Medicine, Division of Clinical Chemistry, Karolinska Institutet, Stockholm, Sweden.
| | | | | | | |
Collapse
|
133
|
Nylén H, Sergel S, Forsberg L, Lindemalm S, Bertilsson L, Wide K, Diczfalusy U. Cytochrome P450 3A activity in mothers and their neonates as determined by plasma 4β-hydroxycholesterol. Eur J Clin Pharmacol 2011; 67:715-22. [DOI: 10.1007/s00228-010-0984-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 12/14/2010] [Indexed: 11/29/2022]
|
134
|
Misaka S, Kurosawa S, Uchida S, Yoshida A, Kato Y, Kagawa Y, Yamada S. Evaluation of the pharmacokinetic interaction of midazolam with ursodeoxycholic acid, ketoconazole and dexamethasone by brain benzodiazepine receptor occupancy. J Pharm Pharmacol 2010; 63:58-64. [DOI: 10.1111/j.2042-7158.2010.01176.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Abstract
Objectives
To clarify whether alterations in midazolam pharmacokinetics resulting from changes in cytochrome P450 3A (CYP3A) activity lead to changes in its pharmacodynamic effects, benzodiazepine receptor occupancy was measured in the brain of rats after oral administration of midazolam.
Methods
Receptor occupancy was measured by radioligand binding assay in rats pretreated with ursodeoxycholic acid (UDCA), ketoconazole and dexamethasone, and the plasma concentration of midazolam was simultaneously determined.
Key findings
There was a significant increase in the apparent dissociation constant and decrease in the maximum number of binding sites for specific [3H]flunitrazepam binding after oral administration of midazolam at pharmacologically relevant doses, suggesting that midazolam binds significantly to brain benzodiazepine receptors. Pretreatment with UDCA significantly enhanced the binding. This correlated well with significant enhancement by UDCA of the plasma midazolam concentration. The brain benzodiazepine receptor binding of oral midazolam was significantly enhanced by pretreatment with ketoconazole, a potent inhibitor of CYP3A, whereas it was significantly reduced by treatment with dexamethasone, an inducer of this enzyme. These effects paralleled changes in the plasma concentration of midazolam.
Conclusions
The results indicate that pharmacokinetic changes such as altered CYP3A activity significantly influence the pharmacodynamic effect of midazolam by affecting occupancy of benzodiazepine receptors in the brain. They also suggest in-vivo or ex-vivo time-dependent measurements of receptor occupancy by radioligand binding assay to be a tool for elucidating the pharmacokinetic interaction of benzodiazepines with other agents in pre-clinical and clinical evaluations.
Collapse
Affiliation(s)
- Shingen Misaka
- Department of Pharmacokinetics and Pharmacodynamics, Global Center of Excellence (COE), Practical Pharmacy and Clinical Pharmaceutics, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Souhei Kurosawa
- Department of Pharmacokinetics and Pharmacodynamics, Global Center of Excellence (COE), Practical Pharmacy and Clinical Pharmaceutics, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Shinya Uchida
- Department of Pharmacokinetics and Pharmacodynamics, Global Center of Excellence (COE), Practical Pharmacy and Clinical Pharmaceutics, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Akira Yoshida
- Department of Pharmacokinetics and Pharmacodynamics, Global Center of Excellence (COE), Practical Pharmacy and Clinical Pharmaceutics, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Yoshihisa Kato
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Yoshiyuki Kagawa
- Department of Pharmacokinetics and Pharmacodynamics, Global Center of Excellence (COE), Practical Pharmacy and Clinical Pharmaceutics, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Shizuo Yamada
- Department of Pharmacokinetics and Pharmacodynamics, Global Center of Excellence (COE), Practical Pharmacy and Clinical Pharmaceutics, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| |
Collapse
|
135
|
Inoue SI, Yoshinari K, Sugawara M, Yamazoe Y. Activated Sterol Regulatory Element-Binding Protein-2 Suppresses Hepatocyte Nuclear Factor-4-Mediated Cyp3a11 Expression in Mouse Liver. Mol Pharmacol 2010; 79:148-56. [DOI: 10.1124/mol.110.068577] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
|
136
|
Fluconazole-induced intoxication with phenytoin in a patient with ultra-high activity of CYP2C9. Eur J Clin Pharmacol 2010; 66:791-5. [PMID: 20405111 DOI: 10.1007/s00228-010-0820-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Accepted: 03/26/2010] [Indexed: 10/19/2022]
Abstract
PURPOSE The cytochrome P450 enzyme CYP2C9 metabolizes several important drugs, such as warfarin and oral antidiabetic drugs. The enzyme is polymorphic, and all known alleles, for example, CYP2C9*2 and*3, give decreased activity. Ultra-high activity of the enzyme has not yet been reported. METHODS We present a patient with Behçet's disease who required treatment with high doses of phenytoin. When fluconazole, a potent inhibitor of CYP2C9, was added to the treatment regimen, the patient developed ataxia, tremor, fatigue, slurred speech and somnolence, indicating phenytoin intoxication. On suspicion of ultra-high activity of CYP2C9, a phenotyping test for CYP2C9 with losartan was performed. RESULTS The patient was shown to have a higher activity of CYP2C9 than any of the 190 healthy Swedish Caucasians used as controls. CONCLUSIONS Our finding of an ultrarapid metabolism of losartan and phenytoin may apply to other CYP2C9 substrates, where inhibition of CYP2C9 may cause severe adverse drug reactions.
Collapse
|
137
|
Sex and CYP3A5 genotype influence total CYP3A activity: high CYP3A activity and a unique distribution of CYP3A5 variant alleles in Ethiopians. THE PHARMACOGENOMICS JOURNAL 2010; 11:130-7. [PMID: 20231858 DOI: 10.1038/tpj.2010.16] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The objectives of the this study were to assess the influence of CYP3A5 genotype and sex on the variability in total CYP3A activity and to compare 4β-hydroxycholesterol and omeprazole sulfoxidation as phenotypic markers for CYP3A activity in Ethiopians. Healthy subjects (n=150) were genotyped for CYP3A5*3, *6 and *7 using allele-specific PCR and Taqman genotyping assays. Plasma levels of 4β-hydroxycholesterol, 3 h post-dose omeprazole and omeprazole sulfone, were determined by gas chromatography-mass spectrometry and high performance liquid chromatography, respectively. The frequency of CYP3A5*1, *3, *6 and *7 was 20.5, 67.3, 12.2 and 0%, respectively. The mean plasma 4β-hydroxycholesterol level was 35.4 ng ml⁻¹. The mean 4β-hydroxycholesterol level (P=0.0001) and the 4β-hydroxycholesterol/cholesterol ratio (P=0.004) were higher in women than in men. CYP3A5 genotype significantly correlated with the plasma 4β-hydroxycholesterol concentration (P=0.003) and 4β-hydroxycholesterol/cholesterol ratio (P=0.0002). The omeprazole/omeprazole sulfone ratio was significantly correlated with 4β-hydroxycholesterol and 4β-hydroxycholesterol/cholesterol ratio in CYP3A5*0/*0 genotypes but not in individuals carrying the CYP3A5*1 allele. No correlation of omeprazole/omeprazole sulfone ratio with sex or CYP3A5 genotype was observed. A clear gene-dose effect implies plasma 4β-hydroxycholesterol level as a useful endogenous biomarker for total CYP3A activity (CYP3A5 plus CYP3A4) whereas the omeprazole/omeprazole sulfone ratio reflects mainly CYP3A4 activity. Sex and CYP3A5 genotype influence total CYP3A activity. Ethiopians display high total CYP3A activity and a unique distribution of CYP3A5 variant alleles not described hitherto.
Collapse
|
138
|
Affiliation(s)
- Norihito Shibata
- Department of Cellular and Molecular Medicine, University of California
| | | |
Collapse
|
139
|
Marathe PH, Rodrigues AD. Examination of CYP3A and P-glycoprotein-mediated drug-drug interactions using animal models. Methods Mol Biol 2010; 596:385-403. [PMID: 19949933 DOI: 10.1007/978-1-60761-416-6_17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
With the advent of polytherapy for cancer treatment it has become prudent to minimize, as much as possible, the potential for drug-drug interactions (DDI). Toward this end, the metabolic and transporter pathways involved in the disposition of a drug candidate (phenotyping) and potential for inhibition and induction of drug-metabolizing enzymes and transporters are evaluated in vitro. Such in vitro human data can be made available prior to human dosing and enable in vitro to in vivo-based predictions of clinical outcomes. Despite some success, however, in vitro systems are not dynamic and sometimes fail to predict drug-drug interactions for a variety of reasons. In comparison, relatively less effort has been made to evaluate predictions based on data derived from in vivo animal models. This chapter will attempt to summarize different examples from the literature where animal models have been used to predict cytochrome P450 3A (CYP3A)- and P-glycoprotein-based DDI. When employing data from animal models one needs to be aware of species differences in enzyme- and transporter-activity leading to differences in pharmacokinetics, clearance pathways as well as species differences in selectivity and affinity of probe substrates and inhibitors. Because of these differences, in vivo animal studies alone, cannot be predictive of human DDI. Despite these caveats, the information obtained from validated in vivo animal models may prove useful when used in conjunction with in vitro-in vivo extrapolation methods. Such an integrated data set can be used to select drug candidates with a reduced DDI potential.
Collapse
Affiliation(s)
- Punit H Marathe
- Metabolism and Pharmacokinetics, Bristol-Myers Squibb, Pennington, NJ, USA.
| | | |
Collapse
|
140
|
Allmyr M, Panagiotidis G, Sparve E, Diczfalusy U, Sandborgh-Englund G. Human Exposure to Triclosan via Toothpaste does not change CYP3A4 Activity or Plasma Concentrations of Thyroid Hormones. Basic Clin Pharmacol Toxicol 2009; 105:339-44. [DOI: 10.1111/j.1742-7843.2009.00455.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
141
|
Patel JP, Brocks DR. The effect of oral lipids and circulating lipoproteins on the metabolism of drugs. Expert Opin Drug Metab Toxicol 2009; 5:1385-98. [DOI: 10.1517/17425250903176439] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
142
|
Carvalho JFS, Cruz Silva MM, Moreira JN, Simões S, Sá e Melo ML. Efficient Chemoenzymatic Synthesis, Cytotoxic Evaluation, and SAR of Epoxysterols. J Med Chem 2009; 52:4007-19. [DOI: 10.1021/jm9003973] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- João F. S. Carvalho
- Centro de Estudos Farmacêuticos, Laboratório Quíımica Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal, Laboratório de Tecnologia Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal, Center for Neurosciense and Cell Biology, University of Coimbra, Portugal
| | - M. Manuel Cruz Silva
- Centro de Estudos Farmacêuticos, Laboratório Quíımica Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal, Laboratório de Tecnologia Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal, Center for Neurosciense and Cell Biology, University of Coimbra, Portugal
| | - João N. Moreira
- Centro de Estudos Farmacêuticos, Laboratório Quíımica Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal, Laboratório de Tecnologia Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal, Center for Neurosciense and Cell Biology, University of Coimbra, Portugal
| | - Sérgio Simões
- Centro de Estudos Farmacêuticos, Laboratório Quíımica Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal, Laboratório de Tecnologia Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal, Center for Neurosciense and Cell Biology, University of Coimbra, Portugal
| | - M. Luisa Sá e Melo
- Centro de Estudos Farmacêuticos, Laboratório Quíımica Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal, Laboratório de Tecnologia Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-548 Coimbra, Portugal, Center for Neurosciense and Cell Biology, University of Coimbra, Portugal
| |
Collapse
|
143
|
Abstract
We assessed the suitability of 4beta-hydroxycholesterol (4betaOH-C) as an endogenous cytochrome P450 3A (CYP3A) phenotyping metric. 4betaOH-C and its ratio to cholesterol (4betaOH-C/C) were determined in five cocktail phenotyping studies, with and without co-medication with a potential CYP3A inhibitor. These parameters were compared with established midazolam-based CYP3A metrics: clearance after intravenous (i.v.) administration (M-Cl) and apparent clearance after oral administration (M-Cl/F), reflecting hepatic and overall activity, respectively. In a common evaluation of periods without co-medication, there was a slight positive correlation of 4betaOH-C and 4betaOH-C/C with midazolam metrics: M-Cl (r = 0.239 and 0.348, respectively) and M-Cl/F (r = 0.267 and 0.353, respectively); P (one-sided) < 0.05. Co-medication with lopinavir/ritonavir caused a strong decrease in midazolam metrics and a mild decrease in cholesterol metrics. However, the intake of propiverine resulted in opposite trends for midazolam-based and cholesterol-based metrics. The information currently available does not justify the use of 4betaOH-C for estimation of basal CYP3A activity. Further studies to address the temporal variations in local CYP3A activity are needed to assess its role as a biomarker during CYP3A inhibition.
Collapse
|
144
|
Griffiths WJ, Wang Y. Analysis of neurosterols by GC-MS and LC-MS/MS. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 877:2778-805. [PMID: 19560986 DOI: 10.1016/j.jchromb.2009.05.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 05/07/2009] [Accepted: 05/09/2009] [Indexed: 10/20/2022]
Abstract
The term neurosteroid was coined by Baulieu and colleagues in Paris towards the end of the last century to describe steroids which are synthesised in the central or peripheral nervous system [E.E. Baulieu, Psychoneuroendocrinology 23 (1998) 963-87]. This definition was restricted to side-chain "shortened" steroids with 21 carbon atoms or less, and excluded sterols and their carboxylic acids with an intact side-chain. By analogy, we now use the term neurosterol to describe C(27) sterols synthesised in the nervous system. In this review we discuss the biological importance of neurosterols, and how they are extracted, isolated, and analysed by GC-MS and LC-MS/MS, from brain and relevant body fluids. We present applications of methodology employed for analysis of specific sterols and comment on the relative merits of the methods employed. Finally, the importance of future in-depth "sterolomic" investigations of brain is highlighted.
Collapse
Affiliation(s)
- William J Griffiths
- Institute of Mass Spectrometry, School of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK.
| | | |
Collapse
|
145
|
Honda A, Yamashita K, Hara T, Ikegami T, Miyazaki T, Shirai M, Xu G, Numazawa M, Matsuzaki Y. Highly sensitive quantification of key regulatory oxysterols in biological samples by LC-ESI-MS/MS. J Lipid Res 2009; 50:350-7. [DOI: 10.1194/jlr.d800040-jlr200] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
146
|
Kurosawa S, Uchida S, Ito, Y, Yamada S. Effect of ursodeoxycholic acid on the pharmacokinetics of midazolam and CYP3A in the liver and intestine of rats. Xenobiotica 2009; 39:162-70. [DOI: 10.1080/00498250802621680] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
147
|
|
148
|
Diczfalusy U, Kanebratt KP, Bredberg E, Andersson TB, Böttiger Y, Bertilsson L. 4beta-hydroxycholesterol as an endogenous marker for CYP3A4/5 activity. Stability and half-life of elimination after induction with rifampicin. Br J Clin Pharmacol 2008; 67:38-43. [PMID: 19006545 DOI: 10.1111/j.1365-2125.2008.03309.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
AIMS The oxysterol 4beta-hydroxycholesterol has been suggested as a marker for CYP3A4/5 activity. We have previously shown that plasma 4beta-hydroxycholesterol continues to increase for several weeks after maximal induction of CYP3A4/5 by carbamazepine at the dose given. In the present study we aimed to determine the time course of the decrease in plasma 4beta-hydroxycholesterol after termination of induction of CYP3A4/5 by rifampicin. An additional aim was to determine the variation in plasma level of 4beta-hydroxycholesterol with time in 12 untreated healthy volunteers. METHODS Twenty-four healthy subjects were allocated into three study groups of equal sizes. The volunteers were treated with rifampicin (either 20 mg day(-1), 100 mg day(-1) or 500 mg day(-1)) for 2 weeks. Blood samples were taken before, during and after rifampicin treatment. In another group of 12 untreated volunteers blood samples were collected at different time points in order to determine the intraindividual variations in plasma 4beta-hydroxycholesterol concentrations. Plasma levels of 4beta-hydroxycholesterol were determined by isotope-dilution gas chromatography-mass spectrometry. RESULTS Rifampicin treatment increased plasma 4beta-hydroxycholesterol levels. After termination of rifampicin treatment plasma levels of 4beta-hydroxycholesterol decreased slowly with an apparent half-life of 17 days. The intraindividual variation in plasma levels of 4beta-hydroxycholesterol in untreated subjects was low, with coefficients of variation of between 4.8 and 13.2% over a period of 3 months. CONCLUSIONS After termination of induction of CYP3A4/5, plasma 4beta-hydroxycholesterol levels decreased slowly during 8 weeks. The half-life of elimination (17 days) resembled that of cholesterol rather than other oxysterols. The long half-life results in stable plasma concentrations with time.
Collapse
Affiliation(s)
- Ulf Diczfalusy
- Division of Clinical Chemistry, Department of Laboratory Medicine at Karolinska Institutet, Karolinska University Hospital, Huddinge, Stockholm, Sweden.
| | | | | | | | | | | |
Collapse
|
149
|
Stahl S, Davies MR, Cook DI, Graham MJ. Nuclear hormone receptor-dependent regulation of hepatic transporters and their role in the adaptive response in cholestasis. Xenobiotica 2008; 38:725-77. [DOI: 10.1080/00498250802105593] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
150
|
Kanebratt KP, Diczfalusy U, Bäckström T, Sparve E, Bredberg E, Böttiger Y, Andersson TB, Bertilsson L. Cytochrome P450 Induction by Rifampicin in Healthy Subjects: Determination Using the Karolinska Cocktail and the Endogenous CYP3A4 Marker 4β-Hydroxycholesterol. Clin Pharmacol Ther 2008; 84:589-94. [DOI: 10.1038/clpt.2008.132] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|