1. The objective of this study was to investigate the effects of four food chemicals, namely butylated hydroxytoluene (BHT), curcumin (CC), propyl gallate (PG) and thiabendazole (TB), on cytochrome ...P450 (CYP) forms in cultured human hepatocytes.
2. Treatment of human hepatocytes for 72 h with 2-200 µM TB produced concentration-dependent increases in CYP1A2, CYP2B6 and CYP3A4 mRNA levels, whereas treatment with BHT increased CYP2B6 and CYP3A4 mRNA levels. CYP1A2, CYP2B6 and CYP3A4 mRNA levels were induced around 48-, 21- and 9-fold, respectively, by 200 µM TB, with CYP2B6 and CYP 3A4 mRNA levels being induced around 12- and 7-fold, respectively, by 200 µM BHT.
3. In contrast, the treatment of human hepatocytes for 72 h with PG and CC had little or no effect on CYP mRNA levels.
4. The treatment of human hepatocytes with TB also induced CYP1A-dependent 7-ethoxyresorufin O-deethylase activity, whereas BHT induced CYP3A-dependent testosterone 6 -hydroxylase activity.
5. In summary, the results demonstrate that TB is a mixed inducer of CYP forms in human hepatocytes inducing CYP1A, CYP2B and CYP3A forms, whereas BHT is an inducer of CYP2B and CYP3A forms.
We report on a NuSTAR and XMM-Newton program that has observed a sample of three extremely luminous, heavily obscured WISE-selected active galactic nuclei (AGNs) at z ~ 2 across a broad X-ray band ...(0.1-79 keV). The parent sample, selected to be faint or undetected in the WISE 3.4 mu m (W1) and 4.6 mu m (W2) bands but bright at 12 mu m (W3) and 22 mu m (W4), are extremely rare, with only ~1000 so-called "W1 W2-dropouts" across the extragalactic sky. These are among the most AGNs known, though the optical spectra rarely show evidence of a broad-line region and the selection criteria imply heavy obscuration even at rest-frame 1.5 mu m. The discovery of a significant population of heavily obscured, extremely luminous AGNs would not conform to the standard paradigm of a receding torus, in which more luminous quasars are less likely to be obscured, and instead suggests that an additional source of obscuration is present in these extreme sources.
The aim of this study was to investigate the mitogenic effects of some inducers of cytochrome P450 (CYP) isoforms in rat liver. Female Sprague-Dawley CD rats were treated with 100 mg/kg per day of ...either sodium phenobarbitone (NaPB), barbituric acid (BA), isoniazid (ISN),
β-naphthoflavone (BNF), pregnenolone-16
α-carbonitrile (PCN), miconazole (MIC) or clotrimazole (CLOT), 75 mg/kg per day methylclofenapate (MCP), 50 mg/kg per day dexamethasone (DEX) and 500 mg/kg per day troleandomycin (TAO) by daily oral gavage for four days. Treatment with all compounds except BA, ISN and MIC, significantly increased relative liver weight. Administration of NaPB, PCN, DEX, MIC, CLOT and TAO all induced total CYP content, and by Western immunoblotting, levels of CYP3A isoforms in hepatic microsomal fractions. Apart from CLOT, all these compounds induced microsomal testosterone 6
β-hydroxylase activity. By measurement of marker enzyme activities and Western immunoblotting with antibodies to CYP1A2, CYP2B1/2 and CYP2E1, BNF, NaPB, ISN and MCP were shown to induce CYP1A2, CYP2B1/2, CYP2E and CYP4A isoforms, respectively. Replicative DNA synthesis was studied by implanting osmotic pumps containing 5-bromo-2′-deoxyuridine 1 day before the commencement of treatment with the enzyme inducers. Hepatocyte labelling index values were significantly increased by treatment with NaPB, PCN, MCP, CLOT and TAO, but not by BA, ISN, BNF, DEX and MIC. These studies demonstrate that while CYP2B and CYP4A enzyme inducers may stimulate replicative DNA synthesis, only some CYP3A enzyme inducers are mitogenic agents in rat liver.
Background and Objectives
The core pharmacological treatment of Post‐Traumatic Stress Disorder (PTSD) is selective serotonin reuptake inhibitors (SSRIs), although remission is only around 30% with ...them. Many patients will self‐treat with opioids and due to the opiate system involvement in dysphoric mood and anxiety/stress responses, it is likely that antagonism of the kappa opioid receptor (KOR) system represents a potential target for treatment of PTSD. The aim of this study is to compare response of PTSD symptoms when antagonizing KOR via buprenorphine/naloxone compared to SSRIs or opioid therapy.
Methods
A retrospective chart review of patients in the MEDVAMC between June 1, 2010 and June 30, 2016 was conducted. Inclusion criteria included patients with a documented diagnosis of PTSD with at least two documented PTSD scores (either PCLC or PC‐PTSD). Exclusion criteria included patients not prescribed one of the study medications (ie, buprenorphine, SSRI, or opiate for chronic pain), and patients not on the study medication for at least 30 days.
Results
Buprenorphine patients exhibited the lowest final average PTSD score (2.47) and the largest change from baseline (−24.0%) compared to opioids (−16.1%) or SSRIs (1.16%). The average buprenorphine dose was 23.3 mg/day, and the average length of therapy was 860 days.
Conclusions
Buprenorphine may help decrease PTSD symptoms more than SSRIs or opioids alone. Prospective studies are needed to determine whether these effects are reproducible.
Scientific Significance
Pharmacotherapy advancements in PTSD treatment have been limited and the kappa opioid receptor system presents a new target that warrants further research. (Am J Addict 2019;XX:1–6)
A rapid and facile tandem solvent solid phase extraction method was established to isolate the heterocyclic aromatic amines (HAAs) 2-amino-3,8-dimethylimidazo4,5-fquinoxaline (8-MeIQx), ...2-amino-3,4,8-trimethylimidazo4,5-fquinoxaline, 2-amino-1-methyl-6-phenylimidazo4,5-bpyridine, and 2-amino-9H-pyrido2,3-bindole from urine. The HAAs were separated by reversed phase liquid chromatography and quantified by electrospray ionization tandem mass spectrometry (ESI/MS/MS) using selected reaction monitoring. The limits of detection and quantitation of these HAAs approached 1−3 and 2−8 pg/mL, respectively, using only 0.3 mL of urine for analysis. Full product ion spectra were acquired to corroborate analyte identities. The pretreatment of urine from human volunteers that had consumed a grilled beef meal with acid or base at 70 °C increased the concentration of HAAs by as much as 6-fold, indicating the presence of phase II conjugates of the parent compounds. HAAs containing an N-methylimidazole moiety undergo facile cleavage of the N-methyl group under collision-induced dissociation conditions, and MS/MS analysis in the constant neutral loss scan mode monitoring the transition M + H+ → M + H − CH3 •+ revealed the presence of two other HAAs. 2-Amino-3-methylimidazo4,5-fquinoxaline (IQx) was identified by coelution of the analyte with synthetic IQx and by acquisition of the product ion spectrum. The second HAA was present in a relatively high abundance in urine. The molecule had the same nominal mass as 8-MeIQx (MH+ at m/z 214), and the product ion spectrum was similar to that of 8-MeIQx. This novel HAA was also found in the grilled meat consumed by the volunteers at a concentration of 8 parts per billion. The accurate mass measurement and product ion spectrum of this molecule by ESI quadrupole time-of-flight mass spectrometry revealed that it was an isomer of 8-MeIQx. This tandem solvent solid phase extraction LC/ESI/MS/MS procedure may be used to rapidly assess the daily exposure to a variety of HAAs in urine.
1. The results of homology modelling of human cytochrome P4501A2 (CYP1A2) based on the CYP2C5 crystal structure are reported. It exhibits improved sequence homology relative to that of CYP102. 2. It ...was demonstrated that many selective substrates for CYP1A2 could fit within the putative active site of the enzyme, and in orientations which agree with documented evidence for CYP1A2-mediated metabolism. 3. Furthermore, a number of amino acid residues lining the haem pocket have been shown, via site-directed mutagenesis, to have an influence on substrate metabolism, and these experimental findings from the literature are consistent with the modelled interactions for selective substrates. 4. The binding affinities of several CYP1A2 substrates have also been calculated from the CYP1A2 active site interactions and they agree closely with experimental values.
TBX21 encodes for the transcription factor T-bet (T-box expressed in T cells), which influences naïve T lymphocyte development and has been implicated in asthma pathogenesis. Specifically, the T-bet ...knockout mouse spontaneously develops airway hyperresponsiveness and other changes consistent with asthma. Because airway responsiveness is moderated by the use of inhaled corticosteroids in asthma, it is conceivable that genetic variation in TBX21 may alter asthma phenotypes in a treatment-specific fashion. Here we demonstrate that the nonsynonymous variation in TBX21 coding for replacement of histidine 33 with glutamine is associated with significant improvement in the PC20 (a measure of airway responsiveness) of asthmatic children in a large clinical trial spanning 4 years. We note that this increase occurs only in the children randomized to inhaled corticosteroids and that it dramatically enhances the overall improvement in PC20 associated with inhaled corticosteroid usage. The average PC20 at trial end for subjects on inhaled corticosteroids possessing a variant allele was in the normal range for nonasthmatics. In cellular models, we show that the TBX21 variant increases T helper 1 and decreases T helper 2 cytokine expression comparably with wild type. TBX21 may thus be an important determinant pharmacogenetic response to the therapy of asthma with inhaled corticosteroids.
1. The metabolism of Zaleplon (CL-284,846; ZAL) has been studied in human liver microsomal preparations and in cDNA-expressed human cytochrome P450 (CYP) isoforms. 2. Human liver microsomes catalysed ...the NADPH-dependent N -deethylation of ZAL to DZAL (CL-284,859), but not to two other known in vivo metabolites, namely M1 (CL345,644) and M2 (CL-345,905). Sigmoidal kinetic plots were observed for ZAL deethylation indicating positive cooperativity. 3. The metabolism of ZAL to DZAL was determined in a characterized bank of 24 human liver microsomalpreparations.Good correlations (r2 = 0.734-0.937) were observed with caffeine 8-hydroxylase, diazepam 3-hydroxylase, dextromethorphan N-demethylase and testosterone 2β-, 6β- and 15β-hydroxylase activities, which are allcatalysed by CYP3A isoforms. In contrast, poor correlations (r2 0.152-0.428) were observed for enzymatic markers for CYP1A2, CYP2A6, CYP2C9 10, CYP2D6, CYP2E1 and CYP4A9 11. 4. The metabolism of ZAL to DZAL in human liver microsomes was inhibited to 6-15% of control by 5-50 μM of the mechanism-based CYP3A inhibitor troleandomycin. Whereas some inhibition of DZAL formation was observed in the presence of 200 μM diethyldithiocarbamate, 5-50 μM furafylline, 2-20 μM sulphaphenazole, 50-500 μM S-mephenytoin and 1-10 μM quinidine had little effect. 5. Using human B-lymphoblastoid cell microsomes containing cDNA-expressed CYP isoforms, ZAL was metabolized to DZAL by CYP3A4, but not to any great extent by CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP2E1. 6. In contrast with ZAL, the NADPH-dependent N-deethylation of M2 to M1 proceeded at only a very low rate with both human liver microsomes and cDNA-expressed CYP3A4. 7. In summary, by correlation analysis, chemical inhibition studies and the use of cDNA-expressed CYPs, ZAL N -deethylation to DZAL in human liver appears to be catalysed by CYP3A isoforms.
The aim of this study was to investigate xenobiotic metabolism and induction of cytochrome P450 (CYP) forms in precision-cut rat liver and lung slices, employing nicotine as a model compound. Freshly ...cut rat liver and lung slices metabolised nicotine to the major metabolite cotinine. Observed
K
m values for cotinine formation in liver and lung slices were 323 and 41.7 μM, respectively, with corresponding
V
max values of 47.2 and 3.21 pmol/min/mg protein, respectively. Rat liver and lung slices were cultured for 48 h with Aroclor 1254, benzo(a)pyrene, nicotine and cotinine. Both Aroclor 1254 and benzo(a)pyrene produced a marked induction of CYP1A-dependent 7-ethoxyresorufin O-deethylase activity in both liver and lung slices. However, while nicotine induced 7-ethoxyresorufin O-deethylase activity in lung slices, but not in liver slices, cotinine did not induce enzyme activity in either liver or lung slices. Overall, while higher rates of nicotine metabolism were observed in rat liver slices, nicotine-induced CYP1A form induction was observed in lung slices. These results demonstrate the usefulness of precision-cut tissue slices for studying tissue differences in xenobiotic metabolism and CYP form induction.
1. The construction of a three-dimensional model of human CYP2E1 is reported. It is based on homology with the haemoprotein domain of the unusual bacterial P450, CYP102, which is of known crystal ...structure. 2. Interactive docking of a number of human CYP2E1 substrates is consistent with their known positions of CYP2E1-mediated metabolism, where specific interactions with key active site amino acid side-chains appear to rationalize the binding and orientation of substrate molecules. 3. Amino acid residues within the putative active site of human CYP2E1, including those associated with the binding of substrates and inhibitors, are shown to correspond with those identified by site-directed mutagenesis experiments conducted on CYP2 family isoforms, and they are known to affect substrate metabolism regioselectivity. 4. Consequently, it was found that the CYP2E1 active site exhibits complementarity with the structural characteristics of known substrates and inhibitors of this enzyme, including their relatively low molecular weights and disposition of hydrogen bond-forming groups.
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