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Sample records for hepatic drug-metabolizing enzymes

  1. Effects of naturally occurring coumarins on hepatic drug-metabolizing enzymes inmice

    SciTech Connect

    Kleiner, Heather E. Xia, Xiaojun; Sonoda, Junichiro; Zhang, Jun; Pontius, Elizabeth; Abey, Jane; Evans, Ronald M.; Moore, David D.; DiGiovanni, John

    2008-10-15

    Cytochromes P450 (P450s) and glutathione S-transferases (GSTs) constitute two important enzyme families involved in carcinogen metabolism. Generally, P450s play activation or detoxifying roles while GSTs act primarily as detoxifying enzymes. We previously demonstrated that oral administration of the linear furanocoumarins, isopimpinellin and imperatorin, modulated P450 and GST activities in various tissues of mice. The purpose of the present study was to compare a broader range of naturally occurring coumarins (simple coumarins, and furanocoumarins of the linear and angular type) for their abilities to modulate hepatic drug-metabolizing enzymes when administered orally to mice. We now report that all of the different coumarins tested (coumarin, limettin, auraptene, angelicin, bergamottin, imperatorin and isopimpinellin) induced hepatic GST activities, whereas the linear furanocoumarins possessed the greatest abilities to induce hepatic P450 activities, in particular P450 2B and 3A. In both cases, this corresponded to an increase in protein expression of the enzymes. Induction of P4502B10, 3A11, and 2C9 by xenobiotics often is a result of activation of the pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR). Using a pregnane X receptor reporter system, our results demonstrated that isopimpinellin activated both PXR and its human ortholog SXR by recruiting coactivator SRC-1 in transfected cells. In CAR transfection assays, isopimpinellin counteracted the inhibitory effect of androstanol on full-length mCAR, a Gal4-mCAR ligand-binding domain fusion, and restored coactivator binding. Orally administered isopimpinellin induced hepatic mRNA expression of Cyp2b10, Cyp3a11, and GSTa in CAR(+/+) wild-type mice. In contrast, the induction of Cyp2b10 mRNA by isopimpinellin was attenuated in the CAR(-/-) mice, suggesting that isopimpinellin induces Cyp2b10 via the CAR receptor. Overall, the current data indicate that naturally occurring coumarins have

  2. Can chronic maternal drug therapy alter the nursing infant's hepatic drug metabolizing enzyme pattern?

    PubMed

    Toddywalla, V S; Patel, S B; Betrabet, S S; Kulkarni, R D; Kombo, I; Saxena, B N

    1995-10-01

    This study was carried out to investigate whether minute quantities of maternal drugs ingested over an extended period of time by a breast-feeding infant can alter the activity pattern of the infant's hepatic drug metabolizing enzyme (HDME). The HDME activity patterns of 12 breast-fed infants whose mothers were not on drug therapy were compared with those of 11 infants whose mothers had been taking 30 micrograms levo-norgesterel daily for 90 to 195 days (oral contraceptives group) and of 10 infants whose mothers had been taking ethambutol and isoniazid daily since pregnancy (tuberculosis group). As 6 beta hydroxycortisol in urine is considered to be a good and acceptable reflector of HDME activity, it was estimated from the infants' urine using enzyme-linked immunosorbent assay (ELISA) technique. A comparison of the patterns between 90 days of age and 195 days of age of the infants in the control group and the two study groups indicated an increase from 36.6 ng/mL to 58.4 ng/mL at 195 days in the control group. An initial decrease from 36.6 ng/mL to 26.2 ng/mL was noted with commencement of maternal levo-norgesterel therapy, followed by a slow and steady rise to 47.8 ng/mL at 195 days of age, with a shift in the peak from 120 to 135 days of infants age in the oral contraceptive group. A suppressed pattern with decreased levels of 6 beta hydroxycortisol ranging from 19.3 ng/mL to 26.5 ng/mL at 195 days was found in the tuberculosis group. The data were analyzed by two-way analysis of variance (ANOVA) coupled with Duncan's Multiple range test. Both treatment group showed significant differences from the control group at the 0.050 level. The HDME plays an important role in determining the final outcome of any drug in humans, as it controls the metabolism of drugs. Hence, alterations in its activity caused by the transfer of maternal drugs over a prolonged period of time could pose a serious problem to nurslings when they require drugs for their own benefit.

  3. Drug-metabolizing enzymes: mechanisms and functions.

    PubMed

    Sheweita, S A

    2000-09-01

    Drug-metabolizing enzymes are called mixed-function oxidase or monooxygenase and containing many enzymes including cytochrome P450, cytochrome b5, and NADPH-cytochrome P450 reductase and other components. The hepatic cytochrome P450s (Cyp) are a multigene family of enzymes that play a critical role in the metabolism of many drugs and xenobiotics with each cytochrome isozyme responding differently to exogenous chemicals in terms of its induction and inhibition. For example, Cyp 1A1 is particularly active towards polycyclic aromatic hydrocarbons (PAHs), activating them into reactive intermediates those covalently bind to DNA, a key event in the initiation of carcinogenesis. Likewise, Cyp 1A2 activates a variety of bladder carcinogens, such as aromatic amines and amides. Also, some forms of cytochrome P450 isozymes such as Cyp 3A and 2E1 activate the naturally occurring carcinogens (e.g. aflatoxin B1) and N-nitrosamines respectively into highly mutagenic and carcinogenic agents. The carcinogenic potency of PAHs, and other carcinogens and the extent of binding of their ultimate metabolites to DNA and proteins are correlated with the induction of cytochrome P450 isozymes. Phase II drug-metabolizing enzymes such as glutathione S-transferase, aryl sulfatase and UDP-glucuronyl transferase inactivate chemical carcinogens into less toxic or inactive metabolites. Many drugs change the rate of activation or detoxification of carcinogens by changing the activities of phases I and II drug-metabolizing enzymes. The balance of detoxification and activation reactions depends on the chemical structure of the agents, and is subjected to many variables that are a function of this structure, or genetic background, sex, endocrine status, age, diet, and the presence of other chemicals. It is important to realize that the enzymes involved in carcinogen metabolism are also involved in the metabolism of a variety of substrates, and thus the introduction of specific xenobiotics may change

  4. [Dosing time based on molecular mechanism of biological clock of hepatic drug metabolic enzyme].

    PubMed

    Matsunaga, Naoya

    2009-11-01

    The mammalian circadian pacemaker stays in the paired suprachiasmatic nuclei (SCN). Recent several studies reveal that the circadian rhythms of physiology and behavior are controlled by clock genes. In addition, the effectiveness and toxicity of many drugs vary depending on dosing time associated with 24-h rhythms of biochemical, physiological, and behavioral processes under the control of the circadian clock. Acetaminophen (APAP) is a widely used analgesic drug, and is mainly biotransformed and eliminated as nontoxic conjugates with glucuronic acid and sulfuric acid. Only a small portion of the dose is mainly bioactivated by CYP2E1 to N-acetyl-p-benzoquinone imine (NAPQI), a reactive toxic intermediate. For APAP overdose, glucuronidation and sulfation are saturated and the formation of NAPQI increases. However, the exact mechanisms underlying the chronotoxicity of APAP have not been clarified yet. In the present study, we have clarified that there was a significant dosing time-dependent difference in hepatotoxicity induced by APAP in mice. The mechanism may be related to the rhythmicity of CYP2E1 activity and GSH conjugation. In additon, we investigated whether the liver transcription factor hepatic nuclear factor-1alpha (HNF-1alpha) and clock genes undergoing astriking 24-h rhythm in mouse liver contribute to the 24-h regulation of CYP2E1 activity. A significant 24-h rhythmicity was demonstrated for CYP2E1 activity, protein levels and mRNA levels. HNF-1alpha and clock genes may contribute to produce the 24-h rhythm of CYP2E1 mRNA levels. Metabolism by CYP and GSH conjugation are common metabolic pathways for many drugs such as APAP. These findings support the concept that choosing the most appropriate time of day to administer the drugs associated with metabolic rhythmicity such as CYP and GSH conjugation may reduce hepatotoxicity in experimental and clinical situations. 24-h rhythm of CYP2E1 activity was controlled by HNF-1alpha and clock gene, in a

  5. Evaluation of the synergistic effect of Allium sativum, Eugenia jambolana, Momordica charantia, Ocimum sanctum, and Psidium guajava on hepatic and intestinal drug metabolizing enzymes in rats

    PubMed Central

    Kumar, Devendra; Trivedi, Neerja; Dixit, Rakesh K.

    2016-01-01

    Aims/Background: This study was to investigated the synergistic effect of polyherbal formulations (PHF) of Allium sativum L., Eugenia jambolana Lam., Momordica charantia L., Ocimum sanctum Linn., and Psidium guajava L. in the inhibition/induction of hepatic and intestinal cytochrome P450 (CYPs) and Phase-II conjugated drug metabolizing enzymes (DMEs). Consumption of these herbal remedy has been extensively documented for diabetes treatment in Ayurveda. Methodology: PHF of these five herbs was prepared, and different doses were orally administered to Sprague–Dawley rats of different groups except control group. Expression of mRNA and activity of DMEs were examined by real-time polymerase chain reaction and high performance liquid chromatography in isolated liver and intestine microsomes in PHF pretreated rats. Results: The activities of hepatic and intestinal Phase-II enzyme levels increased along with mRNA levels except CYP3A mRNA level. PHF administration increases the activity of hepatic and intestinal UDP-glucuronyltransferase and glutathione S-transferase in response to dose and time; however, the activity of hepatic sulfotransferase increased at higher doses. Conclusions: CYPs and Phase-II conjugated enzymes levels can be modulated in dose and time dependent manner. Observations suggest that polyherbal formulation might be a possible cause of herb-drug interaction, due to changes in pharmacokinetic of crucial CYPs and Phase-II substrate drug. PMID:27757267

  6. Inhibition of lipopolysaccharide-induced liver injury in rats treated with a hepatic drug-metabolizing enzyme inducer p,p'-DDT.

    PubMed

    Shimada, Yuko; Tomita, Mariko; Yoshida, Toshinori; Fukuyama, Tomoki; Katoh, Yoshitaka; Ohnuma-Koyama, Aya; Takahashi, Naofumi; Soma, Katsumi; Kojima, Sayuri; Ohtsuka, Ryoichi; Takeda, Makio; Kuwahara, Maki; Harada, Takanori

    2015-03-01

    Hepatocellular hypertrophy in association with drug-metabolizing enzyme induction is considered to be an adaptive change associated with drug metabolism. To improve our understanding of liver hypertrophy, we determined the effect of a single ip injection of either lipopolysaccharide (LPS) or vehicle in male F344 rats with hepatocellular hypertrophy induced by oral delivery of p,p'-DDT for 2 weeks. The rats were sacrificed 3h or 24h after LPS or vehicle injection. LPS induced a focal hepatocellular necrosis in rats fed the control diet. When rats pre-treated with p,p'-DDT were injected with LPS, necrotic foci surrounded by ballooned hepatocytes were observed in the liver. The change was consistent with reduced LPS-mediated increases in plasma hepatic biomarkers, neutrophil influx, and apoptosis, and also associated with hepatic mRNA levels of TNF-α, CYPs, and NOS2. By contrast, when combined with p,p'-DDT and LPS, faint hepatocellular fatty change was extended, together with a synergistic increase in total blood cholesterol. These results suggest that hepatocytes exposed to p,p'-DDT are protected from the cell-lethal toxic effects of an exogenous stimulus, resulting in cell ballooning rather than necrosis in association with reduced inflammation and apoptosis, but compromised by an adverse effect on lipid metabolism.

  7. 21 CFR 862.3360 - Drug metabolizing enzyme genotyping system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Drug metabolizing enzyme genotyping system. 862... Test Systems § 862.3360 Drug metabolizing enzyme genotyping system. (a) Identification. A drug metabolizing enzyme genotyping system is a device intended for use in testing deoxyribonucleic acid...

  8. 21 CFR 862.3360 - Drug metabolizing enzyme genotyping system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Drug metabolizing enzyme genotyping system. 862... Test Systems § 862.3360 Drug metabolizing enzyme genotyping system. (a) Identification. A drug metabolizing enzyme genotyping system is a device intended for use in testing deoxyribonucleic acid...

  9. 21 CFR 862.3360 - Drug metabolizing enzyme genotyping system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Drug metabolizing enzyme genotyping system. 862... Test Systems § 862.3360 Drug metabolizing enzyme genotyping system. (a) Identification. A drug metabolizing enzyme genotyping system is a device intended for use in testing deoxyribonucleic acid...

  10. 21 CFR 862.3360 - Drug metabolizing enzyme genotyping system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Drug metabolizing enzyme genotyping system. 862... Test Systems § 862.3360 Drug metabolizing enzyme genotyping system. (a) Identification. A drug metabolizing enzyme genotyping system is a device intended for use in testing deoxyribonucleic acid...

  11. Chemoprotective activity of boldine: modulation of drug-metabolizing enzymes.

    PubMed

    Kubínová, R; Machala, M; Minksová, K; Neca, J; Suchý, V

    2001-03-01

    Possible chemoprotective effects of the naturally occurring alkaloid boldine, a major alkaloid of boldo (Peumus boldus Mol.) leaves and bark, including in vitro modulations of drug-metabolizing enzymes in mouse hepatoma Hepa-1 cell line and mouse hepatic microsomes, were investigated. Boldine manifested inhibition activity on hepatic microsomal CYP1A-dependent 7-ethoxyresorufin O-deethylase and CYP3A-dependent testosterone 6 beta-hydroxylase activities and stimulated glutathione S-transferase activity in Hepa-1 cells. In addition to the known antioxidant activity, boldine could decrease the metabolic activation of other xenobiotics including chemical mutagens.

  12. 21 CFR 862.3360 - Drug metabolizing enzyme genotyping system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Drug metabolizing enzyme genotyping system. 862.3360 Section 862.3360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... drug metabolizing enzyme. This device is used as an aid in determining treatment choice...

  13. Alteration of drug metabolizing enzymes in sulphite oxidase deficiency

    PubMed Central

    Tutuncu, Begum; Kuçukatay, Vural; Arslan, Sevki; Sahin, Barbaros; Semiz, Asli; Sen, Alaattin

    2012-01-01

    The aim of this study was to investigate the possible effects of sulphite oxidase (SOX, E.C. 1.8.3.1) deficiency on xenobiotic metabolism. For this purpose, SOX deficiency was produced in rats by the administration of a low molybdenum diet with concurrent addition of 200 ppm tungsten to their drinking water. First, hepatic SOX activity in deficient groups was measured to confirm SOX deficiency. Then, aminopyrine N-demethylase, aniline 4-hydroxylase, aromatase, caffeine N-demethylase, cytochrome b5 reductase, erythromycin N-demethylase, ethoxyresorufin O-deethylase, glutathione S-transferase, N-nitrosodimethylamine N-demethylase and penthoxyresorufin O-deethylase activities were determined to follow changes in the activity of drug metabolizing enzymes in SOX-deficient rats. Our results clearly demonstrated that SOX deficiency significantly elevated A4H, caffeine N-demethylase, erythromycin N-demethylase and N-nitrosodimethylamine N-demethylase activities while decreasing ethoxyresorufin O-deethylase and aromatase activities. These alterations in drug metabolizing enzymes can contribute to the varying susceptibility and response of sulphite-sensitive individuals to different drugs and/or therapeutics used for treatments. PMID:22798713

  14. Modulation of hepatic drug metabolizing enzymes and oxidative status by rooibos (Aspalathus linearis) and Honeybush (Cyclopia intermedia), green and black (Camellia sinensis) teas in rats.

    PubMed

    Marnewick, Jeanine L; Joubert, Elizabeth; Swart, Pieter; Van Der Westhuizen, Francois; Gelderblom, Wentzel C

    2003-12-31

    Rooibos and honeybush teas significantly (P < 0.05) enhanced the activity of cytosolic glutathione S-transferase alpha. A significant (P < 0.05) to marginal (P < 0.1) increase in the activity of the microsomal UDP-glucuronosyl transferase was obtained with unprocessed rooibos and honeybush teas, respectively. Oxidized glutathione (GSSG) levels were significantly (P < 0.05) reduced in the liver of all tea treated rats while reduced glutathione (GSH) was markedly increased in the liver of the herbal tea treated rats. These changes resulted in a significant (P < 0.05) increase in the GSH/GSSG ratio by the unprocessed, processed rooibos and unprocessed honeybush teas. Green and black teas markedly to significantly decreased the oxygen radical absorbance capacity in liver homogenates, respectively. Modulation of phase II drug metabolizing enzymes and oxidative status in the liver may be important events in the protection against adverse effects related to mutagenesis and oxidative damage.

  15. Drug metabolizing enzyme systems in the houbara bustard (Chlamydotis undulata).

    PubMed

    Bailey, T A; John, A; Mensah-Brown, E P; Garner, A; Samour, J; Raza, H

    1998-10-01

    This study compared catalytic and immunochemical properties of drug metabolizing phase I and II enzyme systems in houbara bustard (Chlamydotis undulata) liver and kidney and rat liver. P450 content in bustard liver (0.34 +/- 0.03 nmol mg-1 protein) was 50% lower than that of rat liver (0.70 +/- 0.02 nmol mg-1 protein). With the exception of aniline hydroxylase activity, monooxygenase activities using aminopyrine, ethoxyresorufin and ethoxycoumarin as substrates were all significantly lower than corresponding rat liver enzymes. As found in mammalian systems the P450 activities in the bird liver were higher than in the kidney. Immunohistochemical analysis of microsomes using antibodies to rat hepatic P450 demonstrated that bustard liver and kidney express P4502C11 homologous protein; no appreciable cross-reactivity was observed in bustards using antibodies to P4502E1, 1A1 or 1A2 isoenzymes. Glutathione content and glutathione S-transferase (GST) activity in bustard liver were comparable with those of rat liver. GST activity in the kidney was 65% lower than the liver. Western blotting of liver and kidney cytosol with human GST isoenzyme-specific antibodies revealed that the expression of alpha-class of antibodies exceeds mu in the bustard. In contrast, the pi-class of GST was not detected in the bustard liver. This data demonstrates that hepatic and renal microsomes from the bustard have multiple forms of phase I and phase II enzymes. The multiplicity and tissue specific expression of xenobiotic metabolizing enzymes in bustards may play a significant role in determining the pharmacokinetics of drugs and susceptibility of the birds to various environmental pollutants and toxic insults.

  16. Role of constitutive androstane receptor in Toll-like receptor-mediated regulation of gene expression of hepatic drug-metabolizing enzymes and transporters.

    PubMed

    Shah, Pranav; Guo, Tao; Moore, David D; Ghose, Romi

    2014-01-01

    Impairment of drug disposition in the liver during inflammation has been attributed to downregulation of gene expression of drug-metabolizing enzymes (DMEs) and drug transporters. Inflammatory responses in the liver are primarily mediated by Toll-like receptors (TLRs). We have recently shown that activation of TLR2 or TLR4 by lipoteichoic acid (LTA) and lipopolysaccharide (LPS), respectively, leads to the downregulation of gene expression of DMEs/transporters. However, the molecular mechanism underlying this downregulation is not fully understood. The xenobiotic nuclear receptors, pregnane X receptor (PXR) and constitutive androstane receptor (CAR), regulate the expression of DMEs/transporter genes. Downregulation of DMEs/transporters by LTA or LPS was associated with reduced expression of PXR and CAR genes. To determine the role of CAR, we injected CAR(+/+) and CAR(-/-) mice with LTA or LPS, which significantly downregulated (~40%-60%) RNA levels of the DMEs, cytochrome P450 (Cyp)3a11, Cyp2a4, Cyp2b10, uridine diphosphate glucuronosyltransferase 1a1, amine N-sulfotransferase, and the transporter, multidrug resistance-associated protein 2, in CAR(+/+) mice. Suppression of most of these genes was attenuated in LTA-treated CAR(-/-) mice. In contrast, LPS-mediated downregulation of these genes was not attenuated in CAR(-/-) mice. Induction of these genes by mouse CAR activator 1,4-bis-[2-(3,5-dichloropyridyloxy)]benzene was sustained in LTA- but not in LPS-treated mice. Similar observations were obtained in humanized CAR mice. We have replicated these results in primary hepatocytes as well. Thus, LPS can downregulate DME/transporter genes in the absence of CAR, whereas the effect of LTA on these genes is attenuated in the absence of CAR, indicating the potential involvement of CAR in LTA-mediated downregulation of DME/transporter genes.

  17. A Comparative Study for the Evaluation of Two Doses of Ellagic Acid on Hepatic Drug Metabolizing and Antioxidant Enzymes in the Rat

    PubMed Central

    Celik, Gurbet; Semiz, Aslı; Karakurt, Serdar; Arslan, Sevki; Adali, Orhan; Sen, Alaattin

    2013-01-01

    The present study was designed to evaluate different doses of ellagic acid (EA) in vivo in rats for its potential to modulate hepatic phases I, II, and antioxidant enzymes. EA (10 or 30 mg/kg/day, intragastrically) was administered for 14 consecutive days, and activity, protein, and mRNA levels were determined. Although the cytochrome P450 (CYP) 2B and CYP2E enzyme activities were decreased significantly, the activities of all other enzymes were unchanged with the 10 mg/kg/day EA. In addition, western-blot and qRT-PCR results clearly corroborated the above enzyme expressions. On the other hand, while the NAD(P)H:quinone oxidoreductase 1 (NQO1), catalase (CAT), glutathione peroxidase (GPX), and glutathione S-transferase (GST) activities were increased significantly, CYP1A, 2B, 2C, 2E, and 19 enzyme activities were reduced significantly with 30 mg/kg/day EA. In addition, CYP2B, 2C6, 2E1, and 19 protein and mRNA levels were substantially decreased by the 30 mg/kg/day dose of EA, but the CYP1A protein, and mRNA levels were not changed. CYP3A enzyme activity, protein and mRNA levels were not altered by neither 10 nor 30 mg/kg/day ellagic acid. These results indicate that EA exerts a dose-dependent impact on the metabolism of chemical carcinogens and drugs by affecting the enzymes involved in xenobiotics activation/detoxification and antioxidant pathways. PMID:23971029

  18. Interplay of drug metabolizing enzymes with cellular transporters.

    PubMed

    Böhmdorfer, Michaela; Maier-Salamon, Alexandra; Riha, Juliane; Brenner, Stefan; Höferl, Martina; Jäger, Walter

    2014-11-01

    Many endogenous and xenobiotic substances and their metabolites are substrates for drug metabolizing enzymes and cellular transporters. These proteins may not only contribute to bioavailability of molecules but also to uptake into organs and, consequently, to overall elimination. The coordinated action of uptake transporters, metabolizing enzymes, and efflux pumps, therefore, is a precondition for detoxification and elimination of drugs. As the understanding of the underlying mechanisms is important to predict alterations in drug disposal, adverse drug reactions and, finally, drug-drug interactions, this review illustrates the interplay between selected uptake/efflux transporters and phase I/II metabolizing enzymes.

  19. Clinically Relevant Genetic Variations in Drug Metabolizing Enzymes

    PubMed Central

    Pinto, Navin; Dolan, M. Eileen

    2011-01-01

    In the field of pharmacogenetics, we currently have a few markers to guide physicians as to the best course of therapy for patients. For the most part, these genetic variants are within a drug metabolizing enzyme that has a large effect on the degree or rate at which a drug is converted to its metabolites. For many drugs, response and toxicity are multi-genic traits and understanding relationships between a patient's genetic variation in drug metabolizing enzymes and the efficacy and/or toxicity of a medication offers the potential to optimize therapies. This review will focus on variants in drug metabolizing enzymes with predictable and relatively large impacts on drug efficacy and/or toxicity; some of these drug/gene variant pairs have impacted drug labels by the United States Food and Drug Administration. The challenges in identifying genetic markers and implementing clinical changes based on known markers will be discussed. In addition, the impact of next generation sequencing in identifying rare variants will be addressed. PMID:21453273

  20. Enzyme kinetics in drug metabolism: fundamentals and applications.

    PubMed

    Nagar, Swati; Argikar, Upendra A; Tweedie, Donald J

    2014-01-01

    Enzymes are protein catalysts that lower the energy barrier for a reaction and speed the rate of a chemical change. The kinetics of reactions catalyzed by enzymes, as well as several mechanisms underlying the kinetics, have been comprehensively studied and written in textbooks (1, 2). The importance of quantitative evaluation of enzymatic processes has been recognized in many fields of study, including biochemistry, molecular biology, and pharmaceutical sciences to name a few. In pharmaceutical sciences, the applications of enzyme kinetics range from hit finding efforts for new chemical entities on a pharmacological target to concentration effect relationships to large-scale biosynthesis. The study of the science of drug metabolism has two principal concepts-rate and extent. While understanding disposition pathways and identification of metabolites provides an insight into the extent of metabolism, kinetics of depletion of substrates (endogenous or exogenous) and formation of metabolites deals with the rate of metabolism. The current textbook specifically focuses on kinetics of drug-metabolizing enzymes, detailing specific enzyme classes, and discusses kinetics as they apply to drug transporters. This textbook also outlines additional factors that contribute to the kinetics of reactions catalyzed by these proteins such as variability in isoforms (pharmacogenomics) and experimental factors including key concepts such as alterations of substrate concentrations due to binding. Applications of these approaches in predicting kinetic parameters and alternative approaches for enzymes (systems biology) and transporters are also discussed. The final section focuses on real-life examples (case studies) to try and exemplify the applications of enzyme kinetic principles. This chapter provides a brief overview outlining some key concepts within each of the sections and the chapters within this textbook.

  1. Sex- and age-dependent gene expression in human liver: An implication for drug-metabolizing enzymes.

    PubMed

    Uno, Yasuhiro; Takata, Ryo; Kito, Go; Yamazaki, Hiroshi; Nakagawa, Kazuko; Nakamura, Yusuke; Kamataki, Tetsuya; Katagiri, Toyomasa

    2017-02-01

    Sex and age differences in hepatic expression of drug-metabolizing enzyme genes could cause variations in drug metabolism, but has not been fully elucidated, especially in Asian population. In this study, the global expression of human hepatic genes was analyzed by microarrays in 40 Japanese subjects (27 males and 13 females). Thirty-five sex-biased genes were identified (P < 0.005). Whereas, 60 age-biased genes in two age groups, <60 years and ≥70 years (P < 0.001), were identified in males. By Gene Ontology analysis, the sex-biased genes were related to protein catabolism and modification, while the age-biased genes were related to transcription regulation and cell death. Quantitative polymerase chain reaction confirmed the female-biased expression of drug-metabolizing enzyme genes BChE, CYP4X1, and SULT1E1 (≥1.5-fold, P < 0.05). Further analysis of drug-metabolizing enzyme genes indicated that expression of CYP2A6 and CYP3A4 in females in the ≥70 age group was less than in the <60 age group (≥1.5-fold, P < 0.05), and this trend was also observed for PXR expression in males (≥1.5-fold, P < 0.05). The results presented provide important insights into hepatic physiology and function, especially drug metabolism, with respect to sex and age.

  2. Cadmium effect on microsomal drug-metabolizing enzyme activity in rat livers with respect to differences in age and sex

    SciTech Connect

    Ando, M.

    1982-04-01

    The effect of cadmium on the hepatic microsomal drug-metabolizing enzyme system was investigated. Cadmium chloride caused the conversion of cytochrome P-450 to P-420 in rat liver microsomes. The destruction of cytochrome P-450 by cadmium caused the reduction of microsomal drug-metabolizing enzyme activity and prolonged the pentobarbital sleeping time. There is a sex-related difference in the ability of cadmium to inhibit the hepatic drug metabolism in rats: male rats are more sensitive to cadmium than females. The effective period when cadmium prolonged their sleep depended upon the age of rats; older rats were more sensitive to cadmium than younger ones. The maximum increase of sleeping time depended upon the dose level of cadium, and the rate constant of the equations seems to depend upon the age of the animals.

  3. Expression profile of early estradiol-responsive genes in cynomolgus macaque liver: implications for drug-metabolizing enzymes.

    PubMed

    Ise, Ryota; Kito, Go; Uno, Yasuhiro

    2012-01-01

    Estrogen plays important roles in estrogen-responsive tissues, such as mammary glands, ovaries, and the uterus. In the liver, the major drug metabolizing organ, estrogen is known to regulate expression of some drug-metabolizing enzymes. Due to the lack of information on the role of estrogen in hepatic gene expression in primate species, we previously investigated the late response of hepatic gene expression to estradiol in cynomolgus macaques. To understand the early response of hepatic gene expression to estradiol, in this study, microarray analysis was conducted using cynomolgus macaque liver samples collected at 1 h and 5 h after estradiol injection. Comparison of expression profiles in estradiol and solvent (control)-treated ovariectomized cynomolgus macaques revealed 27 differentially expressed genes (>2.0-fold), including 18 at 1 h and 9 at 5 h after estradiol injection. As indicated by Gene Ontology analysis, these genes were related to oxidoreductase activity and transferase activity, partly representing important aspects of drug-metabolizing enzymes. Further analysis by quantitative polymerase chain reaction revealed that estradiol down-regulated CYP2A24, CYP2C76, and CYP2E1 (>2.0-fold) at 1 h and up-regulated GSTM5 (>2.0-fold) at 5 h after estradiol injection. These results suggest that the short-term estradiol treatment influenced expression of hepatic genes, including drug-metabolizing enzyme genes, in cynomolgus macaque liver.

  4. Hepatic drug metabolizing profile of Flinders Sensitive Line rat model of depression.

    PubMed

    Kotsovolou, Olga; Ingelman-Sundberg, Magnus; Lang, Matti A; Marselos, Marios; Overstreet, David H; Papadopoulou-Daifoti, Zoi; Johanson, Inger; Fotopoulos, Andrew; Konstandi, Maria

    2010-08-16

    The Flinders Sensitive Line (FSL) rat model of depression exhibits some behavioral, neurochemical, and pharmacological features that have been reported in depressed patients and has been very effective in screening antidepressants. Major factor that determines the effectiveness and toxicity of a drug is the drug metabolizing capacity of the liver. Therefore, in order to discriminate possible differentiation in the hepatic drug metabolism between FSL rats and Sprague-Dawley (SD) controls, their hepatic metabolic profile was investigated in this study. The data showed decreased glutathione (GSH) content and glutathione S-transferase (GST) activity and lower expression of certain major CYP enzymes, including the CYP2B1, CYP2C11 and CYP2D1 in FSL rats compared to SD controls. In contrast, p-nitrophenol hydroxylase (PNP), 7-ethoxyresorufin-O-dealkylase (EROD) and 16alpha-testosterone hydroxylase activities were higher in FSL rats. Interestingly, the wide spread environmental pollutant benzo(alpha)pyrene (B(alpha)P) induced CYP1A1, CYP1A2, CYP2B1/2 and ALDH3c at a lesser extend in FSL than in SD rats, whereas the antidepressant mirtazapine (MIRT) up-regulated CYP1A1/2, CYP2C11, CYP2D1, CYP2E1 and CYP3A1/2, mainly, in FSL rats. The drug also further increased ALDH3c whereas suppressed GSH content in B(alpha)P-exposed FSL rats. In conclusion, several key enzymes of the hepatic biotransformation machinery are differentially expressed in FSL than in SD rats, a condition that may influence the outcome of drug therapy. The MIRT-induced up-regulation of several drug-metabolizing enzymes indicates the critical role of antidepressant treatment that should be always taken into account in the designing of treatment and interpretation of insufficient pharmacotherapy or drug toxicity.

  5. Polyhalogenated biphenyls and phenobarbital: evaluation as inducers of drug metabolizing enzymes in the sheepshead, Archosargus probatocephalus.

    PubMed

    James, M O; Little, P J

    1981-08-01

    Several doses of Aroclor 1254 (polychlorinated biphenyl (PCB) mixture), Firemaster FF1 (polybrominated biphenyl (PBB) mixture), 2,2',4,4',5,5'-hexabromobiphenyl (HBB), 3,3',4,4',5,5'-hexachlorobiphenyl (HCB) and phenobarbital (PB) were administered to the marine fish sheepshead (Archosargus probatocephalus). The PCB and PBB mixtures caused induction of hepatic microsomal benzo[a]pyrene hydroxylase (AHH), 7-ethoxycoumarin O-deethylase (7-EC) and 7-ethoxyresorufin O-deethylase (ERF) activities, but not benzphetamine N-demethylase (BND), epoxide hydrolase (EH) or glutathione S-transferase (GSH-T) activities. This induction pattern is typical of that caused by polycyclic aromatic hydrocarbons (PAH) in fish and mammals or by tetrachlorodibenzo-p-dioxin (TCDD) in mammals. The extent of induction of AHH-activity and cytochrome P-450 content was higher when experiments were carried out in summer (water temperature 25 +/- 4 degrees C) than in winter (water temperature 11 +/- 3 degrees C). Firemaster FF1 (15 mg/kg) induced fish for at least 56 days in both summer and winter at which time the liver concentrations of PBB were in the ppm range. PCB concentrations in the ppm range have been found in fish from polluted lakes and seas, thus we may expect that environmental exposure to PCB is sufficient to induce hepatic mixed function oxidase (MFO) activities. The PCB isomer 3,3'4,4'5,5'-HCB, which induces the same spectrum of hepatic drug-metabolizing activities as TCDD and PAH in rats, had a broadly similar effect in the sheepshead. Another purified isomer, 2,2',4,4',5,5'-HBB, which induces the same enzymes as PB in rats, had no effect on drug-metabolizing activities in sheepshead. PB was also without effect on sheepshead hepatic drug-metabolizing enzymes, although a typical narcotic effect was produced in PB-treated sheepshead. Our studies provide further evidence that drug-metabolizing activities in fish liver are readily induced by chemicals like TCDD or PAH, but we fail to

  6. Pharmacogenetics of drug-metabolizing enzymes in US Hispanics

    PubMed Central

    Duconge, Jorge; Cadilla, Carmen L.; Ruaño, Gualberto

    2015-01-01

    Although the Hispanic population is continuously growing in the United States, they are underrepresented in pharmacogenetic studies. This review addresses the need for compiling available pharmacogenetic data in US Hispanics, discussing the prevalence of clinically relevant polymorphisms in pharmacogenes encoding for drug-metabolizing enzymes. CYP3A5*3 (0.245–0.867) showed the largest frequency in a US Hispanic population. A higher prevalence of CYP2C9*3, CYP2C19*4, and UGT2B7 IVS1+985 A>Gwas observed in US Hispanic vs. non-Hispanic populations. We found interethnic and intraethnic variability in frequencies of genetic polymorphisms for metabolizing enzymes, which highlights the need to define the ancestries of participants in pharmacogenetic studies. New approaches should be integrated in experimental designs to gain knowledge about the clinical relevance of the unique combination of genetic variants occurring in this admixed population. Ethnic subgroups in the US Hispanic population may harbor variants that might be part of multiple causative loci or in linkage-disequilibrium with functional variants. Pharmacogenetic studies in Hispanics should not be limited to ascertain commonly studied polymorphisms that were originally identified in their parental populations. The success of the Personalized Medicine paradigm will depend on recognizing genetic diversity between and within US Hispanics and the uniqueness of their genetic backgrounds. PMID:25431893

  7. Anti-inflammatory agents and inducibility of hepatic drug metabolism.

    PubMed

    Pappas, P; Stephanou, P; Vasiliou, V; Marselos, M

    1998-01-01

    Two rat liver cytosolic aldehyde dehydrogenases, ALDH1 and ALDH3c, are of particular interest because they are inducible by different classes of xenobiotics. ALDHI is mainly increased by phenobarbital-type inducers; polycyclic aromatic hydrocarbons (PAHs), such as 3- methylcholanthrene (3MC), increase ALDH3c enzyme activity in all rat species currently tested. In addition, ALDH3c has been found to reflect the subfamily CYPIA of cytochrome P-450, as well as other enzymes functionally related to the aryl hydrocarbon receptor (the "Ah-receptor enzyme battery"), which is activated by the same type of inducers. In the present study we investigated whether the induction of ALDH3c might be connected with a chemically produced aseptic inflammation of the hepatocyte. To answer this question, we examined the relationship between the induction of ALDH3c by 3MC and the arachidonic acid cascade. Different non-steroid anti-inflammatory drugs (NSAIDs) were tested in combination with 3MC and in post-treatment. The 3MC-induced ALDH3c activity was significantly diminished by the co-administered anti-inflammatory agents. Two microsomal enzyme activities (ethoxyresorufin-O-deethylase, EROD; aryl-hydrocarbon-hydroxylase, AHH) were also decreased. Similar results were obtained with NSAIDs administered to animals pre- treated with 3MC, as far as the ALDH3c activity was concerned, but not for the microsomal enzyme activity (EROD and AHH). In conclusion, the induction of ALDH3c, after PAH treatment, may be related to an aseptic inflammation of the hepatocytes. This effect is reduced by commonly used steroid and non-steroid anti- inflammatory drugs, and although the mechanism of inhibition has not yet been elucidated, it appears likely that ALDH3c and CYP1A activities are associated with the "acute phase" response.

  8. DMET™ (Drug Metabolism Enzymes and Transporters): a pharmacogenomic platform for precision medicine

    PubMed Central

    Arbitrio, Mariamena; Martino, Maria Teresa Di; Scionti, Francesca; Agapito, Giuseppe; Guzzi, Pietro Hiram; Cannataro, Mario

    2016-01-01

    In the era of personalized medicine, high-throughput technologies have allowed the investigation of genetic variations underlying the inter-individual variability in drug pharmacokinetics/pharmacodynamics. Several studies have recently moved from a candidate gene-based pharmacogenetic approach to genome-wide pharmacogenomic analyses to identify biomarkers for selection of patient-tailored therapies. In this aim, the identification of genetic variants affecting the individual drug metabolism is relevant for the definition of more active and less toxic treatments. This review focuses on the potentiality, reliability and limitations of the DMET™ (Drug Metabolism Enzymes and Transporters) Plus as pharmacogenomic drug metabolism multi-gene panel platform for selecting biomarkers in the final aim to optimize drugs use and characterize the individual genetic background. PMID:27304055

  9. Increase in bile flow and biliary excretion of glutathione-derived sulfhydryls in rats by drug-metabolizing enzyme inducers is mediated by multidrug resistance protein 2.

    PubMed

    Johnson, David R; Habeebu, Sultan S M; Klaassen, Curtis D

    2002-03-01

    Glutathione (GSH) is an important cellular constituent for normal liver homeostasis. Certain drug-metabolizing enzyme inducers (i.e., phenobarbital [PB] and pregnenolone-16alpha-carbonitrile [PCN]) increase biliary excretion of GSH-derived sulfhydryls (SH) as well as bile flow, whereas other drug-metabolizing enzyme inducers (i.e., 3-methylcholanthrene [3MC] and benzo(a)pyrene [BaP]), do not. The purpose of the study was to determine whether rat multidrug resistance protein 2 (Mrp2) is the inducible transporter responsible for increasing biliary SH excretion and bile flow. Sprague-Dawley (SD) rats were injected ip daily for 4 days with PB, PCN, 3MC, BaP, or vehicle; Mrp2-null Eisai hyperbilirubinemic (EHBR) rats were injected ip daily for 4 days with PCN or vehicle. Although no drug-metabolizing enzyme inducer altered hepatic GSH in SD rats, PB and PCN significantly increased the rate of biliary SH excretion and bile flow. Neither 3MC nor BaP affected the biliary SH excretion rate or bile flow. In control EHBR rats, despite elevated hepatic GSH, the rate of biliary SH excretion was almost completely eliminated and bile flow was dramatically reduced compared with SD rats. Furthermore, PCN treatment did not affect bile flow or the biliary SH excretion rate in EHBR rats. PB and PCN also increased Mrp2 protein levels, but 3MC and BaP did not. None of the drug-metabolizing enzyme inducers tested significantly increased Mrp2 mRNA levels. PCN increased Mrp2 protein, but not Mrp2 mRNA, in a time-dependent manner. In conclusion, Mrp2 is the inducible efflux transporter responsible for increased biliary SH excretion and bile flow after administration of some drug-metabolizing enzyme inducers.

  10. Induction of xenobiotic receptors, transporters, and drug metabolizing enzymes by oxycodone.

    PubMed

    Hassan, Hazem E; Myers, Alan L; Lee, Insong J; Mason, Clifford W; Wang, Duan; Sinz, Michael W; Wang, Hongbing; Eddington, Natalie D

    2013-05-01

    Perturbations of the expression of transporters and drug-metabolizing enzymes (DMEs) by opioids can be the locus of deleterious drug-drug interactions (DDIs). Many transporters and DMEs are regulated by xenobiotic receptors [XRs; e.g., pregnane X receptor (PXR), constitutive androstane receptor (CAR), and Aryl hydrocarbon receptor (AhR)]; however, there is a paucity of information regarding the influence of opioids on XRs. The objective of this study was to determine the influence of oxycodone administration (15 mg/kg intraperitoneally twice daily for 8 days) on liver expression of XRs, transporters, and DMEs in rats. Microarray, quantitative real-time polymerase chain reaction and immunoblotting analyses were used to identify significantly regulated genes. Three XRs (e.g., PXR, CAR, and AhR), 27 transporters (e.g., ABCB1 and SLC22A8), and 19 DMEs (e.g., CYP2B2 and CYP3A1) were regulated (P < 0.05) with fold changes ranging from -46.3 to 17.1. Using MetaCore (computational platform), we identified a unique gene-network of transporters and DMEs assembled around PXR, CAR, and AhR. Therefore, a series of transactivation/translocation assays were conducted to determine whether the observed changes of transporters/DMEs are mediated by direct activation of PXR, CAR, or AhR by oxycodone or its major metabolites (noroxycodone and oxymorphone). Neither oxycodone nor its metabolites activated PXR, CAR, or AhR. Taken together, these findings identify a signature hepatic gene-network associated with repeated oxycodone administration in rats and demonstrate that oxycodone alters the expression of many transporters and DMEs (without direct activation of PXR, CAR, and AhR), which could lead to undesirable DDIs after coadministration of substrates of these transporters/DMEs with oxycodone.

  11. Systems biology approaches to enzyme kinetics: analyzing network models of drug metabolism.

    PubMed

    Finn, Nnenna A; Kemp, Melissa L

    2014-01-01

    Intracellular drug metabolism involves transport, bioactivation, conjugation, and other biochemical steps. The dynamics of these steps are each dependent on a number of other cellular factors that can ultimately lead to unexpected behavior. In this review, we discuss the confounding processes and coupled reactions within bioactivation networks that require a systems-level perspective in order to fully understand the time-varying behavior. When converting known in vitro characteristics of drug-enzyme interactions into descriptions of cellular systems, features such as substrate availability, cell-to-cell variability, and intracellular redox state deserve special focus. An example of doxorubicin bioactivation is used for discussing points of consideration when constructing and analyzing network models of drug metabolism.

  12. Biotransformation of anthelmintics and the activity of drug-metabolizing enzymes in the tapeworm Moniezia expansa.

    PubMed

    Prchal, Lukáš; Bártíková, Hana; Bečanová, Aneta; Jirásko, Robert; Vokřál, Ivan; Stuchlíková, Lucie; Skálová, Lenka; Kubíček, Vladimír; Lamka, Jiří; Trejtnar, František; Szotáková, Barbora

    2015-04-01

    The sheep tapeworm Moniezia expansa is very common parasite, which affects ruminants such as sheep, goats as well as other species. The benzimidazole anthelmintics albendazole (ABZ), flubendazole (FLU) and mebendazole (MBZ) are often used to treat the infection. The drug-metabolizing enzymes of helminths may alter the potency of anthelmintic treatment. The aim of our study was to assess the activity of the main drug-metabolizing enzymes and evaluate the metabolism of selected anthelmintics (ABZ, MBZ and FLU) in M. expansa. Activities of biotransformation enzymes were determined in subcellular fractions. Metabolites of the anthelmintics were detected and identified using high performance liquid chromatography/ultra-violet/VIS/fluorescence or ultra-high performance liquid chromatography/mass spectrometry. Reduction of MBZ, FLU and oxidation of ABZ were proved as well as activities of various metabolizing enzymes. Despite the fact that the conjugation enzymes glutathione S-transferase, UDP-glucuronosyl transferase and UDP-glucosyl transferase were active in vitro, no conjugated metabolites of anthelmintics were identified either ex vivo or in vitro. The obtained results indicate that sheep tapeworm is able to deactivate the administered anthelmintics, and thus protects itself against their action.

  13. Endotoxin administration to humans inhibits hepatic cytochrome P450-mediated drug metabolism.

    PubMed Central

    Shedlofsky, S I; Israel, B C; McClain, C J; Hill, D B; Blouin, R A

    1994-01-01

    In experimental animals, injection of gram-negative endotoxin (LPS) decreases hepatic cytochrome P450-mediated drug metabolism. To evaluate this phenomenon in a human model of gram-negative sepsis, LPS was administered on two consecutive days to healthy male volunteers during which time a cocktail of antipyrine (AP-250 mg), hexobarbital (HB-500 mg), and theophylline (TH-150 mg) was ingested and the apparent oral clearance of each drug determined. Each subject had a control drug clearance study with saline injections. In the first experiment, six subjects received the drug cocktail 0.5 h after the first dose of LPS. In the second experiment, another six subjects received the drug cocktail 0.5 h after the second dose of LPS. In both experiments, LPS caused the expected physiologic responses of inflammation including fever with increases in serum concentrations of TNF alpha, IL-1 beta, IL-6, and acute phase reactants. In the first experiment, only minor decreases in clearances of the probe drugs were observed (7-12%). However in the second experiment, marked decreases in the clearances of AP (35, 95% CI 18-48%), HB (27, 95% CI 14-34%), and TH (22, 95% CI 12-32%) were seen. The decreases in AP clearance correlated with initial peak values of TNF alpha (r = 0.82) and IL-6 (r = 0.86). These data show that in humans the inflammatory response to even a very low dose of LPS significantly decreases hepatic cytochrome P450-mediated drug metabolism and this effect evolves over a 24-h period. It is likely that septic patients with much higher exposures to LPS have more profound inhibition of drug metabolism. PMID:7989576

  14. Xanthine Oxidoreductase in Drug Metabolism: Beyond a Role as a 
Detoxifying Enzyme

    PubMed Central

    Battelli, Maria Giulia; Polito, Letizia; Bortolotti, Massimo; Bolognesi, Andrea

    2016-01-01

    The enzyme xanthine oxidoreductase (XOR) catalyzes the last two steps of purine catabolism in the highest uricotelic primates. XOR is an enzyme with dehydrogenase activity that, in mammals, may be converted into oxidase activity under a variety of pathophysiologic conditions. XOR activity is highly regulated at the transcriptional and post-translational levels and may generate reactive oxygen and nitrogen species, which trigger different consequences, ranging from cytotoxicity to inflammation. The low specificity for substrates allows XOR to metabolize a number of endogenous metabolites and a variety of exogenous compounds, including drugs. The present review focuses on the role of XOR as a drug-metabolizing enzyme, specifically for drugs with anticancer, antimicrobial, antiviral, immunosuppressive or vasodilator activities, as well as drugs acting on metabolism or inducing XOR expression. XOR has an activating role that is essential to the pharmacological action of quinone drugs, cyadox, antiviral nucleoside analogues, allopurinol, nitrate and nitrite. XOR activity has a degradation function toward thiopurine nucleotides, pyrazinoic acid, methylxanthines and tolbutamide, whose half-life may be prolonged by the use of XOR inhibitors. In conclusion, to avoid potential drug interaction risks, such as a toxic excess of drug bioavailability or a loss of drug efficacy, caution is suggested in the use of XOR inhibitors, as in the case of hyperuricemic patients affected by gout or tumor lysis syndrome, when it is necessary to simultaneously administer therapeutic substances that are activated or degraded by the drug-metabolizing activity of XOR. PMID:27458036

  15. Effect of commercially available green and black tea beverages on drug-metabolizing enzymes and oxidative stress in Wistar rats.

    PubMed

    Yao, Hsien-Tsung; Hsu, Ya-Ru; Lii, Chong-Kuei; Lin, Ai-Hsuan; Chang, Keng-Hao; Yang, Hui-Ting

    2014-08-01

    The effect of commercially available green tea (GT) and black tea (BT) drinks on drug metabolizing enzymes (DME) and oxidative stress in rats was investigated. Male Wistar rats were fed a laboratory chow diet and GT or BT drink for 5 weeks. Control rats received de-ionized water instead of the tea drinks. Rats received the GT and BT drinks treatment for 5 weeks showed a significant increase in hepatic microsomal cytochrome P450 (CYP) 1A1 and CYP1A2, and a significant decrease in CYP2C, CYP2E1 and CYP3A enzyme activities. Results of immunoblot analyses of enzyme protein contents showed the same trend with enzyme activity. Significant increase in UDP-glucuronosyltransferase activity and reduced glutathione content in liver and lungs were observed in rats treated with both tea drinks. A lower lipid peroxide level in lungs was observed in rats treated with GT drink. Electrophoretic mobility shift assay revealed that both tea drinks decreased pregnane X receptor binding to DNA and increased nuclear factor-erythroid 2 p45-related factor 2 binding to DNA. These results suggest that feeding of both tea drinks to rats modulated DME activities and reduced oxidative stress in liver and lungs. GT drink is more effective on reducing oxidative stress than BT drink.

  16. Relevance of induction of human drug-metabolizing enzymes: pharmacological and toxicological implications

    PubMed Central

    PARK, B. K.; KITTERINGHAM, N. R.; PIRMOHAMED, M.; TUCKER, G. T.

    1996-01-01

    1Human drug-metabolizing systems can be induced, or activated, by a large number of exogenous agents including drugs, alcohol, components in the diet and cigarette smoke, as well as by endogenous factors. 2Such perturbation of enzyme activity undoubtedly contributes to both intra- and inter-individual variation both with respect to the rate and route of metabolism for a particular drug. Induction may, in theory, either attenuate the pharmacological response or exacerbate the toxicity of a particular drug, or both. 3The clinical impact of enzyme induction will depend upon the number of different enzyme isoforms affected and the magnitude of the inductive response within an individual, and also on the therapeutic indices of the affected substrates. 4The toxicological implications will be determined either by any change in the route of metabolism, or by a disturbance of the balance between activation and detoxication processes, which may be isozyme selective. PMID:8799511

  17. Update on the Genetic Polymorphisms of Drug-Metabolizing Enzymes in Antiepileptic Drug Therapy

    PubMed Central

    Saruwatari, Junji; Ishitsu, Takateru; Nakagawa, Kazuko

    2010-01-01

    Genetic polymorphisms in the genes that encode drug-metabolizing enzymes are implicated in the inter-individual variability in the pharmacokinetics and pharmaco-dynamics of antiepileptic drugs (AEDs). However, the clinical impact of these polymorphisms on AED therapy still remains controversial. The defective alleles of cytochrome P450 (CYP) 2C9 and/or CYP2C19 could affect not only the pharmacokinetics, but also the pharmacodynamics of phenytoin therapy. CYP2C19 deficient genotypes were associated with the higher serum concentration of an active metabolite of clobazam, N-desmethylclobazam, and with the higher clinical efficacy of clobazam therapy than the other CYP2C19 genotypes. The defective alleles of CYP2C9 and/or CYP2C19 were also found to have clinically significant effects on the inter-individual variabilities in the population pharmacokinetics of phenobarbital, valproic acid and zonisamide. EPHX1 polymorphisms may be associated with the pharmacokinetics of carbamazepine and the risk of phenytoin-induced congenital malformations. Similarly, the UDP-glucuronosyltransferase 2B7 genotype may affect the pharmacokinetics of lamotrigine. Gluthatione S-transferase null genotypes are implicated in an increased risk of hepatotoxicity caused by carbamazepine and valproic acid. This article summarizes the state of research on the effects of mutations of drug-metabolizing enzymes on the pharmacokinetics and pharmacodynamics of AED therapies. Future directions for the dose-adjustment of AED are discussed. PMID:27713373

  18. In vivo cytochrome P450 drug metabolizing enzyme characterization using surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Yanfang; Bachmann, Kenneth A.; Cameron, Brent D.

    2003-07-01

    The development of a rapid, inexpensive, and accurate in vivo phenotyping methodology for characterizing drug-metabolizing phenotypes with reference to the cytochrome P450 (CYP450) enzymes would be very beneficial. In terms of application, in the wake of the human genome project, considerable interest is focused on the development of new drugs whose uses will be tailored to specific genetic polymorphisms, and on the individualization of dosing regimens that are also tailored to meet individual patient needs depending upon genotype. In this investigation, chemical probes for CYP450 enzymes were characterized and identified with Raman spectroscopy. Furthermore, gold-based metal colloid clusters were utilized to generate surface enhanced Raman spectra for each of the chemical probes. Results will be presented demonstrating the ability of SERS to identify minute quantities of these probes on the order needed for in vivo application.

  19. A Multiscale Approach to Modelling Drug Metabolism by Membrane-Bound Cytochrome P450 Enzymes

    PubMed Central

    Sansom, Mark S. P.; Mulholland, Adrian J.

    2014-01-01

    Cytochrome P450 enzymes are found in all life forms. P450s play an important role in drug metabolism, and have potential uses as biocatalysts. Human P450s are membrane-bound proteins. However, the interactions between P450s and their membrane environment are not well-understood. To date, all P450 crystal structures have been obtained from engineered proteins, from which the transmembrane helix was absent. A significant number of computational studies have been performed on P450s, but the majority of these have been performed on the solubilised forms of P450s. Here we present a multiscale approach for modelling P450s, spanning from coarse-grained and atomistic molecular dynamics simulations to reaction modelling using hybrid quantum mechanics/molecular mechanics (QM/MM) methods. To our knowledge, this is the first application of such an integrated multiscale approach to modelling of a membrane-bound enzyme. We have applied this protocol to a key human P450 involved in drug metabolism: CYP3A4. A biologically realistic model of CYP3A4, complete with its transmembrane helix and a membrane, has been constructed and characterised. The dynamics of this complex have been studied, and the oxidation of the anticoagulant R-warfarin has been modelled in the active site. Calculations have also been performed on the soluble form of the enzyme in aqueous solution. Important differences are observed between the membrane and solution systems, most notably for the gating residues and channels that control access to the active site. The protocol that we describe here is applicable to other membrane-bound enzymes. PMID:25033460

  20. Cytochrome P450 Drug Metabolizing Enzymes in Roma Population Samples: Systematic Review of the Literature.

    PubMed

    Szalai, Renata; Hadzsiev, Kinga; Melegh, Bela

    2016-01-01

    The cytochrome P450 drug metabolizing enzymes are highly polymorphic and show inter-individual differences in variability in drug response, which varies widely also with ethnicity. This study aims to summarize the available data on genetic polymorphisms associated with cytochrome enzymes conducted on Roma populations. Our goal was to compare the frequency of the variant alleles, genotypes and predicted phenotypes with corresponding rates from other populations. We carried out a systematic review including the papers published on the pharmacogenetically relevant variants of cytochrome P450 genes related to Roma population. The study was performed using several articles, websites and databases, including PubMed, Ensembl, dbSNP, HapMap and 1000 Genomes Project. This review attempts to summarize and discuss our current knowledge about the frequency distribution of the ever investigated 20 allelic variants of 9 cytochrome genes (CYP1A2, CYP1B1, CYP2B6, CYP2C9, CYP2C19, CYP2C8, CYP2D6, CYP3A5, CYP4F2) in Roma DNA samples and compare them with other populations. Differences between Roma and Hungarian samples are reported for 7 variant genotypes. CYP2C9 *2/*3 and CYP2C19 *2/*2 genotypes showed more than 3-fold differences. Additional differences are displayed for allele frequency of 7 variants (rs762551, rs3745274, rs1058930, rs1065852, rs3892097, rs1057910 and rs4244285) in Roma population samples. The interethnic variability in clinically relevant genetic polymorphisms of drug metabolizing enzymes, which may explain distinct drug response, highlights the need to allow for the ancestry of participants in pharmacogenetic studies.

  1. Changes of drug metabolizing enzymes in the liver of male sheep exposed to either cypermethrin or dimethoate.

    PubMed

    Sheweita, S A; Yousef, M I; Baghdadi, H H; Elshemy, A G

    2012-03-01

    Xenobiotics such as insecticides are metabolized to more or less toxic metabolites by drug-metabolizing enzymes including cytochrome P450 (Cyp P450), cytochrome b5 (Cyp b5), NADPH-cytochrome c reductase (Cyt.c R), N-nitrosdimethylamine-N-demethylase I (NDMA-dI), glutathione (GSH), glutathione s-transferase (GST), and glutathione reductase (GR). Therefore, the present study showed the influence of oral administration of cypermethrin (6 and 12 mg/kg/day) and dimethoate (1.6 and 3.2 mg/kg/day) for 63 consecutive days on the activities of the above mentioned enzymes in the livers of male sheep. Low and high-treatments of sheep with cypermethrin significantly increased the levels of Cyp P450 by 56% and 98%, Cyp b5 by 65% and 80%, GSH by 68% and 74%, and Cyt.c R by 67% and 98%, respectively in a dose-dependent manner. However, low dose of cypermethrin increased the activities of GST and GR by 56% and 91% respectively. In addition, low and high dose-treatments with dimethoate increased the hepatic contents of Cyp P450 by 27% and 40%, GSH by 259% and 132%, whereas NDMA-dI decreased by 27 and 55% respectively, and no change in the content of Cyp b5 and the activity of Cyt.c-R at any given dose of this compound. It is concluded that exposure to cypermethrin and dimethoate significantly changed the hepatic activity of phases I & II drugmetabolizing enzymes in sheep, and these changes are mainly dependent on the administred dose, and also on the type of the tested insecticides. Also, such changes should be considered when therapeutic drugs administered to people exposed to such insecticides.

  2. Correlating structure and function of drug-metabolizing enzymes: progress and ongoing challenges.

    PubMed

    Johnson, Eric F; Connick, J Patrick; Reed, James R; Backes, Wayne L; Desai, Manoj C; Xu, Lianhong; Estrada, D Fernando; Laurence, Jennifer S; Scott, Emily E

    2014-01-01

    This report summarizes a symposium sponsored by the American Society for Pharmacology and Experimental Therapeutics at Experimental Biology held April 20-24 in Boston, MA. Presentations discussed the status of cytochrome P450 (P450) knowledge, emphasizing advances and challenges in relating structure with function and in applying this information to drug design. First, at least one structure of most major human drug-metabolizing P450 enzymes is known. However, the flexibility of these active sites can limit the predictive value of one structure for other ligands. A second limitation is our coarse-grain understanding of P450 interactions with membranes, other P450 enzymes, NADPH-cytochrome P450 reductase, and cytochrome b5. Recent work has examined differential P450 interactions with reductase in mixed P450 systems and P450:P450 complexes in reconstituted systems and cells, suggesting another level of functional control. In addition, protein nuclear magnetic resonance is a new approach to probe these protein/protein interactions, identifying interacting b5 and P450 surfaces, showing that b5 and reductase binding are mutually exclusive, and demonstrating ligand modulation of CYP17A1/b5 interactions. One desired outcome is the application of such information to control drug metabolism and/or design selective P450 inhibitors. A final presentation highlighted development of a CYP3A4 inhibitor that slows clearance of human immunodeficiency virus drugs otherwise rapidly metabolized by CYP3A4. Although understanding P450 structure/function relationships is an ongoing challenge, translational advances will benefit from continued integration of existing and new biophysical approaches.

  3. Correlating Structure and Function of Drug-Metabolizing Enzymes: Progress and Ongoing Challenges

    PubMed Central

    Johnson, Eric F.; Connick, J. Patrick; Reed, James R.; Backes, Wayne L.; Desai, Manoj C.; Xu, Lianhong; Estrada, D. Fernando; Laurence, Jennifer S.

    2014-01-01

    This report summarizes a symposium sponsored by the American Society for Pharmacology and Experimental Therapeutics at Experimental Biology held April 20-24 in Boston, MA. Presentations discussed the status of cytochrome P450 (P450) knowledge, emphasizing advances and challenges in relating structure with function and in applying this information to drug design. First, at least one structure of most major human drug-metabolizing P450 enzymes is known. However, the flexibility of these active sites can limit the predictive value of one structure for other ligands. A second limitation is our coarse-grain understanding of P450 interactions with membranes, other P450 enzymes, NADPH–cytochrome P450 reductase, and cytochrome b5. Recent work has examined differential P450 interactions with reductase in mixed P450 systems and P450:P450 complexes in reconstituted systems and cells, suggesting another level of functional control. In addition, protein nuclear magnetic resonance is a new approach to probe these protein/protein interactions, identifying interacting b5 and P450 surfaces, showing that b5 and reductase binding are mutually exclusive, and demonstrating ligand modulation of CYP17A1/b5 interactions. One desired outcome is the application of such information to control drug metabolism and/or design selective P450 inhibitors. A final presentation highlighted development of a CYP3A4 inhibitor that slows clearance of human immunodeficiency virus drugs otherwise rapidly metabolized by CYP3A4. Although understanding P450 structure/function relationships is an ongoing challenge, translational advances will benefit from continued integration of existing and new biophysical approaches. PMID:24130370

  4. [Involvement of microRNA in the induction of drug-metabolizing enzymes].

    PubMed

    Shizu, Ryota; Numazawa, Satoshi; Yoshida, Takemi

    2012-01-01

    MicroRNAs (miRNAs) are small noncoding RNAs of about 20 nucleotides in length and participate in the post-transcriptional regulation of gene expression. Accumulating evidence indicates that miRNA binds to 3'-UTR of its target mRNAs and thereby destabilizes the transcripts or suppresses the translation. It is expected that miRNAs could have diverse functions and therefore play a role in the gene expression caused by the drug treatment, which have yet to be determined. Demonstration of the participation of specific miRNA in the drug-mediated gene expression would make it a biomarker for the toxicological assessment and help an understanding of molecular machinery of the drug-drug interaction. Under these backgrounds, we investigated the change of miRNAs in the liver of mice treated with phenobarbital, a typical inducer for drug-metabolizing enzymes, and demonstrate the participation of miRNAs in the phenobarbital-regulated gene expression. We investigated the relationship between phenobarbital-mediated changes in miRNA and mRNA by using Agilent miRNA microarray and DNA microarray, followed by real time RT-PCR. From these experiments, it was suggested that the phenobarbital-induced changes in cyp2c29 and mrp3 are regulated by miR-30a and miR-29b, respectively. In addition, we obtained evidence that indicates a phenobarbital-mediated decrease in miR-122, a highly abundant liver-specific miRNA, leads to the activation of the transcription factor CAR and thereby induces drug-metabolizing enzymes.

  5. Impact of dioxin-type induction of drug-metabolizing enzymes on the metabolism of endo- and xenobiotics.

    PubMed

    Schrenk, D

    1998-04-15

    The induction of a number of drug-metabolizing enzymes is among the best-understood biochemical effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related agonists of the aryl hydrocarbon receptor (AhR). Among the cytochrome P450s (CYPs), the genes encoding CYP1A1, 1A2, and 1B1 are responsive to AhR agonists, i.e. their expression is inducible in various mammalian tissues and organs as well as in many types of cell lines and primary cells in culture. In addition, an aldehyde dehydrogenase, an NADPH-quinone-oxidoreductase, and the phase II conjugating enzymes glutathione-S-transferase (GST) Ya and UDP-glucuronosyltransferase 1A1 have been identified as responsive to AhR agonists. Induced expression of these members of the AhR gene battery is thought to be aimed at an improved elimination of the inducing agent and its metabolites. However, the identity of the physiological ligand(s) of the AhR is still obscure. The consequences of induced expression of AhR-regulated genes encoding drug-metabolizing enzymes have been investigated in human populations, e.g. in smokers, and in various experimental models. A prominent example of increased adverse effects due to the induction of CYP1A isozymes is the metabolic activation of carcinogenic aromatic amines and polycyclic aromatic hydrocarbons. An increasing amount of data is also available on the impact of dioxin-type induction on the metabolism of drugs, food constituents, and endogenous substrates. For example, the hepatic clearance of the drug theophylline, which is widely used in asthma therapy, is enhanced significantly in smokers. Increased glucuronidation of thyroxine in rats treated with TCDD or other potent AhR agonists is thought to result in hypothyroxinemia and its biological consequences, such as sustained hyperplasia of the thyroid, bearing a higher risk of thyroid cancer. The relevance of these observations for humans exposed to dioxin-type inducers is discussed.

  6. The Role of Constitutive Androstane Receptor in Oxazaphosphorine-mediated Induction of Drug-metabolizing Enzymes in Human Hepatocytes

    PubMed Central

    Wang, Duan; Li, Linhao; Fuhrman, Jennifer; Ferguson, Stephen; Wang, Hongbing

    2013-01-01

    Purpose The objective of this study was to investigate the roles of the constitutive androstane receptor (CAR) in cyclophosphamide (CPA)- and ifosfamide (IFO)-mediated induction of hepatic drug-metabolizing enzymes (DME). Methods Induction of DMEs was evaluated using real-time RT-PCR and Western blotting analysis in human primary hepatocyte (HPH) cultures. Activation of CAR, pregnane X receptor (PXR), and aryl hydrocarbon receptor by CPA and IFO was assessed in cell-based reporter assays in HepG2 cells and/or nuclear translocation assays in HPHs. Results CYP2B6 reporter activity was significantly enhanced by CPA and IFO in HepG2 cells co-transfected with CYP2B6 reporter plasmid and a chemical-responsive human CAR variant (CAR1+A) construct. Real-time RT-PCR and Western blotting analysis in HPHs showed that both CPA and IFO induced the expressions of CYP2B6 and CYP3A4. Notably, treatment of HPHs with CPA but not IFO resulted in significant nuclear accumulation of CAR, which represents the initial step of CAR activation. Further studies in HPHs demonstrated that selective inhibition of PXR by sulforaphane preferentially repressed IFO- over CPA-mediated induction of CYP2B6. Conclusion These results provide novel insights into the differential roles of CAR in the regulation of CPA- and IFO-induced DME expression and potential drug-drug interactions. PMID:21487929

  7. Cytochrome P4502C9: an enzyme of major importance in human drug metabolism

    PubMed Central

    Miners, John O; Birkett, Donald J

    1998-01-01

    Accumulating evidence indicates that CYP2C9 ranks amongst the most important drug metabolizing enzymes in humans. Substrates for CYP2C9 include fluoxetine, losartan, phenytoin, tolbutamide, torsemide, S-warfarin, and numerous NSAIDs. CYP2C9 activity in vivo is inducible by rifampicin. Evidence suggests that CYP2C9 substrates may also be induced variably by carbamazepine, ethanol and phenobarbitone. Apart from the mutual competitive inhibition which may occur between alternate substrates, numerous other drugs have been shown to inhibit CYP2C9 activity in vivo and/or in vitro. Clinically significant inhibition may occur with coadministration of amiodarone, fluconazole, phenylbutazone, sulphinpyrazone, sulphaphenazole and certain other sulphonamides. Polymorphisms in the coding region of the CYP2C9 gene produce variants at amino acid residues 144 (Arg144Cys) and 359 (Ile359Leu) of the CYP2C9 protein. Individuals homozygous for Leu359 have markedly diminished metabolic capacities for most CYP2C9 substrates, although the frequency of this allele is relatively low. Consistent with the modulation of enzyme activity by genetic and other factors, wide interindividual variability occurs in the elimination and/or dosage requirements of prototypic CYP2C9 substrates. Individualisation of dose is essential for those CYP2C9 substrates with a narrow therapeutic index. PMID:9663807

  8. Polymorphisms in drug-metabolizing enzymes: What is their clinical relevance and why do they exist?

    SciTech Connect

    Nebert, D.W.

    1997-02-01

    The beautiful report by Sachse in this issue of the journal represents the culmination of 2 decades of increasingly exciting work on the {open_quotes}debrisoquine oxidation polymorphism,{close_quotes} one of dozens of pharmacogenetic or ecogenetic polymorphisms that have been shown to have an important impact on innumerable clinical diseases. Pharmacogenetics is the study of the hereditary basis of the differences in responses to drugs. Ecogenetics is the broader field of interindividual differences in response to all environmental chemical and physical agents (e.g., heavy metals, insecticides, compounds formed during combustion, and UV radiation). It is now clear that each of us has his or her own {open_quotes}individual fingerprint{close_quotes} of unique alleles encoding the so-called drug-metabolizing enzymes (DMEs) and the receptors that regulate these enzymes. In this invited editorial, I first introduce the current thinking in the field of DME (and DME-receptor) research and how DMEs have evolved from animal-plant interactions. I then describe the debrisoquine oxidation polymorphism, as well as two other relevant DME polymorphisms; show the relationship between these polymorphisms and human disease; provide examples of synergistic effects caused by the combination of two DME polymorphisms; and discuss the ethical considerations of such research. Last, I speculate on why these allelic frequencies of the DME genes might exist in human populations in the first place. 35 refs.

  9. Constitutive expression of drug metabolizing enzymes and related transcription factors in cattle testis and their modulation by illicit steroids.

    PubMed

    Lopparelli, Rosa Maria; Zancanella, Vanessa; Giantin, Mery; Ravarotto, Licia; Cozzi, Giulio; Montesissa, Clara; Dacasto, Mauro

    2010-10-01

    In veterinary species, little information about extrahepatic drug metabolism is actually available. Therefore, the presence of foremost drug metabolizing enzymes (DMEs) and related transcription factors mRNAs was initially investigated in cattle testis; then, their possible modulation following the in vivo exposure to illicit growth promoters (GPs), which represent a major issue in cattle farming, was explored. All target genes were expressed in cattle testis, albeit to a lower extent compared to liver ones; furthermore, illicit protocols containing dexamethasone and 17β-oestradiol significantly up-regulated cytochrome P450 1A1, 2E1, oestrogen receptor-α and peroxisome proliferator-activated receptor-α mRNA levels. Overall, the constitutive expression of foremost DMEs and related transcription factors was demonstrated for the first time in cattle testis and illicit GPs were shown to affect pre-transcriptionally some of them, with possible consequences upon testicular xenobiotic drug metabolism.

  10. Regulation of drug-metabolizing enzymes by xenobiotic receptors: PXR and CAR☆

    PubMed Central

    Tolson, Antonia H.; Wang, Hongbing

    2010-01-01

    Drug-metabolizing enzymes (DMEs) and transporters play pivotal roles in the disposition and detoxification of numerous foreign and endogenous chemicals. To accommodate chemical challenges, the expression of many DMEs and transporters is up-regulated by a group of ligand-activated transcription factors namely nuclear receptors (NRs). The importance of NRs in xenobiotic metabolism and clearance is best exemplified by the most promiscuous xenobiotic receptors: pregnane X receptor (PXR, NR1I2) and constitutive androstane/activated receptor (CAR, NR1I3). Together, these two receptors govern the inductive expression of a largely overlapping array of target genes encoding phase I and II DMEs, and drug transporters. Moreover, PXR and CAR also represent two distinctive mechanisms of NR activation, whereby CAR demonstrates both constitutive and ligand-independent activation. In this review, recent advances in our understanding of PXR and CAR as xenosensors are discussed with emphasis placed on the differences rather than similarities of these two xenobiotic receptors in ligand recognition and target gene regulation. PMID:20727377

  11. Microarray Analysis of Differentially-Expressed Genes Encoding CYP450 and Phase II Drug Metabolizing Enzymes in Psoriasis and Melanoma

    PubMed Central

    Sumantran, Venil N.; Mishra, Pratik; Bera, Rakesh; Sudhakar, Natarajan

    2016-01-01

    Cytochrome P450 drug metabolizing enzymes are implicated in personalized medicine for two main reasons. First, inter-individual variability in CYP3A4 expression is a confounding factor during cancer treatment. Second, inhibition or induction of CYP3A4 can trigger adverse drug–drug interactions. However, inflammation can downregulate CYP3A4 and other drug metabolizing enzymes and lead to altered metabolism of drugs and essential vitamins and lipids. Little is known about effects of inflammation on expression of CYP450 genes controlling drug metabolism in the skin. Therefore, we analyzed seven published microarray datasets, and identified differentially-expressed genes in two inflammatory skin diseases (melanoma and psoriasis). We observed opposite patterns of expression of genes regulating metabolism of specific vitamins and lipids in psoriasis and melanoma samples. Thus, genes controlling the turnover of vitamin D (CYP27B1, CYP24A1), vitamin A (ALDH1A3, AKR1B10), and cholesterol (CYP7B1), were up-regulated in psoriasis, whereas melanomas showed downregulation of genes regulating turnover of vitamin A (AKR1C3), and cholesterol (CYP39A1). Genes controlling abnormal keratinocyte differentiation and epidermal barrier function (CYP4F22, SULT2B1) were up-regulated in psoriasis. The up-regulated CYP24A1, CYP4F22, SULT2B1, and CYP7B1 genes are potential drug targets in psoriatic skin. Both disease samples showed diminished drug metabolizing capacity due to downregulation of the CYP1B1 and CYP3A5 genes. However, melanomas showed greater loss of drug metabolizing capacity due to downregulation of the CYP3A4 gene. PMID:26901218

  12. Drug Metabolizing Enzyme and Transporter Gene Variation, Nicotine Metabolism, Prospective Abstinence, and Cigarette Consumption.

    PubMed

    Bergen, Andrew W; Michel, Martha; Nishita, Denise; Krasnow, Ruth; Javitz, Harold S; Conneely, Karen N; Lessov-Schlaggar, Christina N; Hops, Hyman; Zhu, Andy Z X; Baurley, James W; McClure, Jennifer B; Hall, Sharon M; Baker, Timothy B; Conti, David V; Benowitz, Neal L; Lerman, Caryn; Tyndale, Rachel F; Swan, Gary E

    2015-01-01

    The Nicotine Metabolite Ratio (NMR, ratio of trans-3'-hydroxycotinine and cotinine), has previously been associated with CYP2A6 activity, response to smoking cessation treatments, and cigarette consumption. We searched for drug metabolizing enzyme and transporter (DMET) gene variation associated with the NMR and prospective abstinence in 2,946 participants of laboratory studies of nicotine metabolism and of clinical trials of smoking cessation therapies. Stage I was a meta-analysis of the association of 507 common single nucleotide polymorphisms (SNPs) at 173 DMET genes with the NMR in 449 participants of two laboratory studies. Nominally significant associations were identified in ten genes after adjustment for intragenic SNPs; CYP2A6 and two CYP2A6 SNPs attained experiment-wide significance adjusted for correlated SNPs (CYP2A6 PACT=4.1E-7, rs4803381 PACT=4.5E-5, rs1137115, PACT=1.2E-3). Stage II was mega-regression analyses of 10 DMET SNPs with pretreatment NMR and prospective abstinence in up to 2,497 participants from eight trials. rs4803381 and rs1137115 SNPs were associated with pretreatment NMR at genome-wide significance. In post-hoc analyses of CYP2A6 SNPs, we observed nominally significant association with: abstinence in one pharmacotherapy arm; cigarette consumption among all trial participants; and lung cancer in four case:control studies. CYP2A6 minor alleles were associated with reduced NMR, CPD, and lung cancer risk. We confirmed the major role that CYP2A6 plays in nicotine metabolism, and made novel findings with respect to genome-wide significance and associations with CPD, abstinence and lung cancer risk. Additional multivariate analyses with patient variables and genetic modeling will improve prediction of nicotine metabolism, disease risk and smoking cessation treatment prognosis.

  13. Induction of drug metabolizing enzymes in polybrominated biphenyl-fed lactating rats and their pups.

    PubMed

    Moore, R W; Dannan, G A; Aust, S D

    1978-04-01

    Polybrominated biphenyls (PBBs) cause a mixed-type (phenobarbital- plus 3-methylcholanthrene-like) induction of liver microsomal drug metabolizing enzymes in rats. However, 2,2',4,4',5,5'-hexabromobiphenyl and 2,2',3,4,4',5,5'-heptabromobiphenyl, which together comprise less than 80% of PBBs (FireMaster), were shown to be strictly phenobarbital-type inducers. Other components (unidentified) must therefore cause the 3-methylcholanthrene-like effects. The potential for PBBs to exert effects on neonates through milk was examined. Lactating rats were fed 0, 0.1, 1.0, or 10 ppm FireMaster for the 18 days following delivery, at which time mothers and most pups were sacrificed. Pups nursing from mothers fed 10 ppm PBBs showed significant increases in liver weights and microsomal protein, and both mothers and pups had increased cytochrome P-450, aminopyrine demethylation, benzo[a]pyrene hydroxylation, and UDP-glucuronyltransferase. Pups nursing from rats fed 1.0 ppm had increases in microsomal protein, cytochrome P-450, aminopyrine demethylation, and benzo[a]pyrene hydroxylation, while their mothers were unaffected. Several pups from the 0, 0.1, and 1.0 ppm groups were maintained on their mother's diets, raised, and allowed to mate. Their pups showed much the same responses to PBBs as did the original group of pups. The effects on both generations of adult female rats were also comparable. PBBs cause a mixed-type induction in both lactating rats and their nursing pups; PBB components responsible for both aspects of this induction must be transmitted through milk. Nursing rats are approximately tenfold more sensitive to the effects of PBBs in their mother's diets than are the dams. The approximate no-effect level for microsomal induction in nursing rats is 0.1 ppm PBBs in the diet of the adult.

  14. Characterizing drug-metabolizing enzymes and transporters that are bona fide CAR-target genes in mouse intestine.

    PubMed

    Park, Shinhee; Cheng, Sunny Lihua; Cui, Julia Yue

    2016-09-01

    Intestine is responsible for the biotransformation of many orally-exposed chemicals. The constitutive androstane receptor (CAR/Nr1i3) is known to up-regulate many genes encoding drug-metabolizing enzymes and transporters (drug-processing genes/DPGs) in liver, but less is known regarding its effect in intestine. Sixty-day-old wild-type and Car(-/-) mice were administered the CAR-ligand TCPOBOP or vehicle once daily for 4 days. In wild-type mice, Car mRNA was down-regulated by TCPOBOP in liver and duodenum. Car(-/-) mice had altered basal intestinal expression of many DPGs in a section-specific manner. Consistent with the liver data (Aleksunes and Klaassen, 2012), TCPOBOP up-regulated many DPGs (Cyp2b10, Cyp3a11, Aldh1a1, Aldh1a7, Gsta1, Gsta4, Gstm1-m4, Gstt1, Ugt1a1, Ugt2b34, Ugt2b36, and Mrp2-4) in specific sections of small intestine in a CAR-dependent manner. However, the mRNAs of Nqo1 and Papss2 were previously known to be up-regulated by TCPOBOP in liver but were not altered in intestine. Interestingly, many known CAR-target genes were highest expressed in colon where CAR is minimally expressed, suggesting that additional regulators are involved in regulating their expression. In conclusion, CAR regulates the basal expression of many DPGs in intestine, and although many hepatic CAR-targeted DPGs were bona fide CAR-targets in intestine, pharmacological activation of CAR in liver and intestine are not identical.

  15. Effect of various diets on the expression of phase-I drug-metabolizing enzymes in livers of mice.

    PubMed

    Guo, Ying; Cui, Julia Yue; Lu, Hong; Klaassen, Curtis D

    2015-01-01

    1. Previous studies have shown that diets can alter the metabolism of drugs; however, it is difficult to compare the effects of multiple diets on drug metabolism among different experimental settings. Phase-I-related genes play a major role in the biotransformation of pro-drugs and drugs. 2. In the current study, effects of nine diets on the mRNA expression of phase-I drug metabolizing enzymes in livers of mice were simultaneously investigated. Compared to the AIN-93M purified diet (control), 73 of the 132 critical phase-I drug-metabolizing genes were differentially regulated by at least one diet. Diet restriction produced the largest number of changed genes (51), followed by the atherogenic diet (27), high-fat diet (25), standard rodent chow (21), western diet (20), high-fructose diet (5), EFA deficient diet (3) and low n-3 FA diet (1). The mRNAs of the Fmo family changed most, followed by Cyp2b and 4a subfamilies, as well as Por (from 1121- to 21-fold increase of theses mRNAs). There were 59 genes not altered by any of these diets. 3. The present results may improve the interpretation of studies with mice and aid in determining effective and safe doses for individuals with different nutritional diets.

  16. Andrographis paniculata Extract and Andrographolide Modulate the Hepatic Drug Metabolism System and Plasma Tolbutamide Concentrations in Rats

    PubMed Central

    Chen, Haw-Wen; Huang, Chin-Shiu; Liu, Pei-Fen; Li, Chien-Chun; Liu, Cheng-Tzu; Chiang, Jia-Rong; Yao, Hsien-Tsung; Lii, Chong-Kuei

    2013-01-01

    Andrographolide is the most abundant terpenoid of A. paniculata which is used in the treatment of diabetes. In this study, we investigated the effects of A. paniculata extract (APE) and andrographolide on the expression of drug-metabolizing enzymes in rat liver and determined whether modulation of these enzymes changed the pharmacokinetics of tolbutamide. Rats were intragastrically dosed with 2 g/kg/day APE or 50 mg/kg/day andrographolide for 5 days before a dose of 20 mg/kg tolbutamide was given. APE and andrographolide reduced the AUC0–12 h of tolbutamide by 37% and 18%, respectively, compared with that in controls. The protein and mRNA levels and enzyme activities of CYP2C6/11, CYP1A1/2, and CYP3A1/2 were increased by APE and andrographolide. To evaluate whether APE or andrographolide affected the hypoglycemic action of tolbutamide, high-fat diet-induced obese mice were used and treated in the same manner as the rats. APE and andrographolide increased CYP2C6/11 expression and decreased plasma tolbutamide levels. In a glucose tolerance test, however, the hypoglycemic effect of tolbutamide was not changed by APE or andrographolide. These results suggest that APE and andrographolide accelerate the metabolism rate of tolbutamide through increased expression and activity of drug-metabolizing enzymes. APE and andrographolide, however, do not impair the hypoglycemic effect of tolbutamide. PMID:23997806

  17. Nuclear receptors CAR and PXR cross talk with FOXO1 to regulate genes that encode drug-metabolizing and gluconeogenic enzymes.

    PubMed

    Kodama, Susumu; Koike, Chika; Negishi, Masahiko; Yamamoto, Yukio

    2004-09-01

    The nuclear receptors CAR and PXR activate hepatic genes in response to therapeutic drugs and xenobiotics, leading to the induction of drug-metabolizing enzymes, such as cytochrome P450. Insulin inhibits the ability of FOXO1 to express genes encoding gluconeogenic enzymes. Induction by drugs is known to be decreased by insulin, whereas gluconeogenic activity is often repressed by treatment with certain drugs, such as phenobarbital (PB). Performing cell-based transfection assays with drug-responsive and insulin-responsive enhancers, glutathione S-transferase pull down, RNA interference (RNAi), and mouse primary hepatocytes, we examined the molecular mechanism by which nuclear receptors and FOXO1 could coordinately regulate both enzyme pathways. FOXO1 was found to be a coactivator to CAR- and PXR-mediated transcription. In contrast, CAR and PXR, acting as corepressors, downregulated FOXO1-mediated transcription in the presence of their activators, such as 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) and pregnenolone 16alpha-carbonitrile, respectively. A constitutively active mutant of the insulin-responsive protein kinase Akt, but not the kinase-negative mutant, effectively blocked FOXO1 activity in cell-based assays. Thus, insulin could repress the receptors by activating the Akt-FOXO1 signal, whereas drugs could interfere with FOXO1-mediated transcription by activating CAR and/or PXR. Treatment with TCPOBOP or PB decreased the levels of phosphoenolpyruvate carboxykinase 1 mRNA in mice but not in Car(-/-) mice. We conclude that FOXO1 and the nuclear receptors reciprocally coregulate their target genes, modulating both drug metabolism and gluconeogenesis.

  18. Quantitative Assessment of Population Variability in Hepatic Drug Metabolism Using a Perfused Three-Dimensional Human Liver Microphysiological System

    PubMed Central

    Tsamandouras, N.; Kostrzewski, T.; Stokes, C. L.; Griffith, L. G.; Hughes, D. J.

    2017-01-01

    In this work, we first describe the population variability in hepatic drug metabolism using cryopreserved hepatocytes from five different donors cultured in a perfused three-dimensional human liver microphysiological system, and then show how the resulting data can be integrated with a modeling and simulation framework to accomplish in vitro–in vivo translation. For each donor, metabolic depletion profiles of six compounds (phenacetin, diclofenac, lidocaine, ibuprofen, propranolol, and prednisolone) were measured, along with metabolite formation, mRNA levels of 90 metabolism-related genes, and markers of functional viability [lactate dehydrogenase (LDH) release, albumin, and urea production]. Drug depletion data were analyzed with mixed-effects modeling. Substantial interdonor variability was observed with respect to gene expression levels, drug metabolism, and other measured hepatocyte functions. Specifically, interdonor variability in intrinsic metabolic clearance ranged from 24.1% for phenacetin to 66.8% for propranolol (expressed as coefficient of variation). Albumin, urea, LDH, and cytochrome P450 mRNA levels were identified as significant predictors of in vitro metabolic clearance. Predicted clearance values from the liver microphysiological system were correlated with the observed in vivo values. A population physiologically based pharmacokinetic model was developed for lidocaine to illustrate the translation of the in vitro output to the observed pharmacokinetic variability in vivo. Stochastic simulations with this model successfully predicted the observed clinical concentration-time profiles and the associated population variability. This is the first study of population variability in drug metabolism in the context of a microphysiological system and has important implications for the use of these systems during the drug development process. PMID:27760784

  19. Genetic variability of drug-metabolizing enzymes: the dual impact on psychiatric therapy and regulation of brain function.

    PubMed

    Stingl, J C; Brockmöller, J; Viviani, R

    2013-03-01

    Polymorphic drug-metabolizing enzymes (DMEs) are responsible for the metabolism of the majority of psychotropic drugs. By explaining a large portion of variability in individual drug metabolism, pharmacogenetics offers a diagnostic tool in the burgeoning era of personalized medicine. This review updates existing evidence on the influence of pharmacogenetic variants on drug exposure and discusses the rationale for genetic testing in the clinical context. Dose adjustments based on pharmacogenetic knowledge are the first step to translate pharmacogenetics into clinical practice. However, also clinical factors, such as the consequences on toxicity and therapeutic failure, must be considered to provide clinical recommendations and assess the cost-effectiveness of pharmacogenetic treatment strategies. DME polymorphisms are relevant not only for clinical pharmacology and practice but also for research in psychiatry and neuroscience. Several DMEs, above all the cytochrome P (CYP) enzymes, are expressed in the brain, where they may contribute to the local biochemical homeostasis. Of particular interest is the possibility of DMEs playing a physiological role through their action on endogenous substrates, which may underlie the reported associations between genetic polymorphisms and cognitive function, personality and vulnerability to mental disorders. Neuroimaging studies have recently presented evidence of an effect of the CYP2D6 polymorphism on basic brain function. This review summarizes evidence on the effect of DME polymorphisms on brain function that adds to the well-known effects of DME polymorphisms on pharmacokinetics in explaining the range of phenotypes that are relevant to psychiatric practice.

  20. Lead Optimization in Discovery Drug Metabolism and Pharmacokinetics/Case study: The Hepatitis C Virus (HCV) Protease Inhibitor SCH 503034.

    PubMed

    Cheng, K-C; Korfmacher, Walter A; White, Ronald E; Njoroge, F George

    2007-06-26

    Lead optimization using drug metabolism and pharmacokinetics (DMPK) parameters has become one of the primary focuses of research organizations involved in drug discovery in the last decade. Using a combination of rapid in vivo and in vitro DMPK screening procedures on a large array of compounds during the lead optimization process has resulted in development of compounds that have acceptable DMPK properties. In this review, we present a general screening paradigm that is currently being used as part of drug discovery at Schering-Plough and we describe a case study using the Hepatitis C Virus (HCV) protease inhibitor program as an example. By using the DMPK optimization tools, a potent HCV protease inhibitor, SCH 503034, was selected for development as a candidate drug.

  1. Assessment of drug metabolism enzyme and transporter pharmacogenetics in drug discovery and early development: perspectives of the I-PWG.

    PubMed

    Brian, William; Tremaine, Larry M; Arefayene, Million; de Kanter, Ruben; Evers, Raymond; Guo, Yingying; Kalabus, James; Lin, Wen; Loi, Cho-Ming; Xiao, Guangqing

    2016-04-01

    Genetic variants of drug metabolism enzymes and transporters can result in high pharmacokinetic and pharmacodynamic variability, unwanted characteristics of efficacious and safe drugs. Ideally, the contributions of these enzymes and transporters to drug disposition can be predicted from in vitro experiments and in silico modeling in discovery or early development, and then be utilized during clinical development. Recently, regulatory agencies have provided guidance on the preclinical investigation of pharmacogenetics, for application to clinical drug development. This white paper summarizes the results of an industry survey conducted by the Industry Pharmacogenomics Working Group on current practice and challenges with using in vitro systems and in silico models to understand pharmacogenetic causes of variability in drug disposition.

  2. Role of farnesoid X receptor in establishment of ontogeny of phase-I drug metabolizing enzyme genes in mouse liver.

    PubMed

    Peng, Lai; Piekos, Stephanie; Guo, Grace L; Zhong, Xiao-Bo

    2016-09-01

    The expression of phase-I drug metabolizing enzymes in liver changes dramatically during postnatal liver maturation. Farnesoid X receptor (FXR) is critical for bile acid and lipid homeostasis in liver. However, the role of FXR in regulating ontogeny of phase-I drug metabolizing genes is not clear. Hence, we applied RNA-sequencing to quantify the developmental expression of phase-I genes in both Fxr-null and control (C57BL/6) mouse livers during development. Liver samples of male C57BL/6 and Fxr-null mice at 6 different ages from prenatal to adult were used. The Fxr-null showed an overall effect to diminish the "day-1 surge" of phase-I gene expression, including cytochrome P450s at neonatal ages. Among the 185 phase-I genes from 12 different families, 136 were expressed, and differential expression during development occurred in genes from all 12 phase-I families, including hydrolysis: carboxylesterase (Ces), paraoxonase (Pon), and epoxide hydrolase (Ephx); reduction: aldoketo reductase (Akr), quinone oxidoreductase (Nqo), and dihydropyrimidine dehydrogenase (Dpyd); and oxidation: alcohol dehydrogenase (Adh), aldehyde dehydrogenase (Aldh), flavin monooxygenases (Fmo), molybdenum hydroxylase (Aox and Xdh), cytochrome P450 (P450), and cytochrome P450 oxidoreductase (Por). The data also suggested new phase-I genes potentially targeted by FXR. These results revealed an important role of FXR in regulation of ontogeny of phase-I genes.

  3. Genetic polymorphisms in human drug-metabolizing enzymes: potential uses of reverse genetics to identify genes of toxicological relevance.

    PubMed

    Puga, A; Nebert, D W; McKinnon, R A; Menon, A G

    1997-03-01

    The human mind was engaged with fundamental questions on the nature of heredity long before the study of genetics became a scientific discipline. Many traits, such as height, eye color, blood pressure, or cancer susceptibility, have been known to run in families, although the genes or combination of genes that underlie these observable characteristics remain unknown in most cases. Differences in susceptibility to environmental agents in humans are likewise determined by variations in genetic background--genetic polymorphisms. In this article, we review the current status of studies on human polymorphisms in drug-metabolizing enzymes and discuss various approaches to the analysis of genetic polymorphisms. We expect that in the near future, novel methods in genetic analysis of human populations will be likely to play a key role in the identification of genes of toxicological relevance.

  4. Effect of radio-detoxified endotoxin on the liver microsomal drug metabolizing enzyme system in rats

    SciTech Connect

    Bertok, L.; Szeberenyi, S.

    1983-06-01

    E. coli endotoxin (LPS) depresses the hepatic microsomal mono-oxygenase activity. Radio-detoxified LPS (TOLERIN: /sup 60/Co irradiated endotoxin preparation) decreases this biotransforming activity to a smaller extent. Phenobarbital, an inducer of this mono-oxygenase system, failed to induce in LPS-treated animals. In radio-detoxified LPS-treated rats, phenobarbital induced the mono-oxygenase and almost fully restored the biotransformation.

  5. Reaction phenotyping: advances in the experimental strategies used to characterize the contribution of drug-metabolizing enzymes.

    PubMed

    Zientek, Michael A; Youdim, Kuresh

    2015-01-01

    During the process of drug discovery, the pharmaceutical industry is faced with numerous challenges. One challenge is the successful prediction of the major routes of human clearance of new medications. For compounds cleared by metabolism, accurate predictions help provide an early risk assessment of their potential to exhibit significant interpatient differences in pharmacokinetics via routes of metabolism catalyzed by functionally polymorphic enzymes and/or clinically significant metabolic drug-drug interactions. This review details the most recent and emerging in vitro strategies used by drug metabolism and pharmacokinetic scientists to better determine rates and routes of metabolic clearance and how to translate these parameters to estimate the amount these routes contribute to overall clearance, commonly referred to as fraction metabolized. The enzymes covered in this review include cytochrome P450s together with other enzymatic pathways whose involvement in metabolic clearance has become increasingly important as efforts to mitigate cytochrome P450 clearance are successful. Advances in the prediction of the fraction metabolized include newly developed methods to differentiate CYP3A4 from the polymorphic enzyme CYP3A5, scaling tools for UDP-glucuronosyltranferase, and estimation of fraction metabolized for substrates of aldehyde oxidase.

  6. The influence of starvation upon hepatic drug metabolism in rats, mice, and guinea pigs.

    NASA Technical Reports Server (NTRS)

    Furner, R. L.; Feller, D. D.

    1971-01-01

    Male rats, mice, and guinea pigs were starved for 1, 2, or 3 days, and the metabolism of ethylmorphine, p-nitroanisole, and aniline was studied. Results suggest that the oxidative enzyme systems studied are not interdependent, and the pathways studied appear to be species dependent.

  7. Effect of caffeine-coconut products interactions on induction of microsomal drug-metabolizing enzymes in Wistar albino rats.

    PubMed

    Abara, A E; Obochi, G O; Malu, S P; Obi-Abang, M; Ekam, V S; Uboh, F E

    2007-01-01

    Effect of caffeine-coconut products interactions on induction of drug-metabolizing enzyme in Wistar albino rats was studied. Twenty rats were randomly divided into four groups: The control group (1) received via oral route a placebo (4.0 ml of distilled water). Groups 2 to 4 were treated for a 14-day period with 50 mg/kg body weight of caffeine, 50 mg/kg body weight of caffeine and 50 mg/kg body weight of coconut water, and 50 mg/kg body weight of caffeine and 50 mg/kg body weight of coconut milk in 4.0 ml of the vehicle via gastric intubation respectively. One day after the final exposure, the animals were anaesthetized by inhalation of an overdose of chloroform. The blood of each rat was collected by cardiac puncture while the liver of each rat was harvested and processed to examine several biochemical parameters, i.e., total protein and RNA levels, protein/RNA ratios, and activities of alanine and aspartate amino transferase (ALT and AST, respectively). The results showed that while ingestion of coconut milk and coconut water increased the values of protein and protein/RNA ratios, it decreased alanine and aspartate amino transferase (ALT and AST) activities. These effects, in turn, enhanced the induction of the metabolizing enzymes and a resultant faster clearance and elimination of the caffeine from the body, there by reducing the toxic effect on the liver.

  8. Nerve Agent Hydrolysis Activity Designed into a Human Drug Metabolism Enzyme

    DTIC Science & Technology

    2011-03-18

    butyrylcholinesterase. Biochemistry 36: 786–795. 19. Vocadlo DJ, Davies GJ, Laine R, Withers SG (2001) Catalysis by hen egg - white lysozyme proceeds via a...residues (grey surface) including V146 and L363 (light blue), as well as the oxyanion hole ( white ). doi:10.1371/journal.pone.0017441.g002 Enzyme Design... lysozyme and protein tyrosine phosphatases [19,20], and apparently support the same role in hCE1. The V146H addition synergistically increased base

  9. Toxicity of xanthene food dyes by inhibition of human drug-metabolizing enzymes in a noncompetitive manner.

    PubMed

    Mizutani, Takaharu

    2009-01-01

    The synthetic food dyes studied were rose bengal (RB), phroxine (PL), amaranth, erythrosine B (ET), allura red, new coccine, acid red (AR), tartrazine, sunset yellow FCF, brilliant blue FCF, and indigo carmine. First, data confirmed that these dyes were not substrates for CYP2A6, UGT1A6, and UGT2B7. ET inhibited UGT1A6 (glucuronidation of p-nitrophenol) and UGT2B7 (glucuronidation of androsterone). We showed the inhibitory effect of xanthene dye on human UGT1A6 activity. Basic ET, PL, and RB in those food dyes strongly inhibited UGT1A6 activity, with IC(50) values = 0.05, 0.04, and 0.015 mM, respectively. Meanwhile, AR of an acidic xanthene food dye showed no inhibition. Next, we studied the inhibition of CYP3A4 of a major phase I drug-metabolizing enzyme and P-glycoprotein of a major transporter by synthetic food dyes. Human CYP3A4 and P-glycoprotein were also inhibited by basic xanthene food dyes. The IC(50) values of these dyes to inhibit CYP3A4 and P-glycoprotein were the same as the inhibition level of UGT1A6 by three halogenated xanthene food dyes (ET, PL, and RB) described above, except AR, like the results with UGT1A6 and UGT2B7. We also confirmed the noninhibition of CYP3A4 and P-gp by other synthetic food dyes. Part of this inhibition depended upon the reaction of (1)O(2) originating on xanthene dyes by light irradiation, because inhibition was prevented by (1)O(2) quenchers. We studied the influence of superoxide dismutase and catalase on this inhibition by dyes and we found prevention of inhibition by superoxide dismutase but not catalase. This result suggests that superoxide anions, originating on dyes by light irradiation, must attack drug-metabolizing enzymes. It is possible that red cosmetics containing phloxine, erythrosine, or rose bengal react with proteins on skin under lighting and may lead to rough skin.

  10. Gallic acid and gallic acid derivatives: effects on drug metabolizing enzymes.

    PubMed

    Ow, Yin-Yin; Stupans, Ieva

    2003-06-01

    Gallic acid and its structurally related compounds are found widely distributed in fruits and plants. Gallic acid, and its catechin derivatives are also present as one of the main phenolic components of both black and green tea. Esters of gallic acid have a diverse range of industrial uses, as antioxidants in food, in cosmetics and in the pharmaceutical industry. In addition, gallic acid is employed as a source material for inks, paints and colour developers. Studies utilising these compounds have found them to possess many potential therapeutic properties including anti-cancer and antimicrobial properties. In this review, studies of the effects of gallic acid, its esters, and gallic acid catechin derivatives on Phase I and Phase II enzymes are examined. Many published reports of the effects of the in vitro effects of gallic acid and its derivatives on drug metabolising enzymes concern effects directly on substrate (generally drug or mutagen) metabolism or indirectly through observed effects in Ames tests. In the case of the Ames test an antimutagenic effect may be observed through inhibition of CYP activation of indirectly acting mutagens and/or by scavenging of metabolically generated mutagenic electrophiles. There has been considerable interest in the in vivo effects of the gallate esters because of their incorporation into foodstuffs as antioxidants and in the catechin gallates with their potential role as chemoprotective agents. Principally an induction of Phase II enzymes has been observed however more recent studies using HepG2 cells and primary cultures of human hepatocytes provide evidence for the overall complexity of actions of individual components versus complex mixtures, such as those in food. Further systematic studies of mechanisms of induction and inhibition of drug metabolising enzymes by this group of compounds are warranted in the light of their distribution and consequent ingestion, current uses and suggested therapeutic potential. However, it

  11. Comparison of metabolism of sesamin and episesamin by drug-metabolizing enzymes in human liver.

    PubMed

    Yasuda, Kaori; Ikushiro, Shinichi; Wakayama, Shuto; Itoh, Toshimasa; Yamamoto, Keiko; Kamakura, Masaki; Munetsuna, Eiji; Ohta, Miho; Sakaki, Toshiyuki

    2012-10-01

    Sesamin and episesamin are two epimeric lignans that are found in refined sesame oil. Commercially available sesamin supplements contain both sesamin and episesamin at an approximate 1:1 ratio. Our previous study clarified the sequential metabolism of sesamin by cytochrome P450 (P450) and UDP-glucuronosyltransferase in human liver. In addition, we revealed that sesamin caused a mechanism-based inhibition (MBI) of CYP2C9, the P450 enzyme responsible for sesamin monocatecholization. In the present study, we compared the metabolism and the MBI of episesamin with those of sesamin. Episesamin was first metabolized to the two epimers of monocatechol, S- and R-monocatechols in human liver microsomes. The P450 enzymes responsible for S- and R-monocatechol formation were CYP2C9 and CYP1A2, respectively. The contribution of CYP2C9 was much larger than that of CYP1A2 in sesamin metabolism, whereas the contribution of CYP2C9 was almost equal to that of CYP1A2 in episesamin metabolism. Docking of episesamin to the active site of CYP1A2 explained the stereoselectivity in CYP1A2-dependent episesamin monocatecholization. Similar to sesamin, the episesamin S- and R-monocatechols were further metabolized to dicatechol, glucuronide, and methylate metabolites in human liver; however, the contribution of each reaction was significantly different between sesamin and episesamin. The liver microsomes from CYP2C19 ultra-rapid metabolizers showed a significant amount of episesamin dicatechol. In this study, we have revealed significantly different metabolism by P450, UDP-glucuronosyltransferase, and catechol-O-methyltransferase for sesamin and episesamin, resulting in different biological effects.

  12. Effects of Curcuma xanthorrhiza Extracts and Their Constituents on Phase II Drug-metabolizing Enzymes Activity

    PubMed Central

    Salleh, Nurul Afifah Mohd; Ismail, Sabariah; Ab Halim, Mohd Rohaimi

    2016-01-01

    Background: Curcuma xanthorrhiza is a native Indonesian plant and traditionally utilized for a range of illness including liver damage, hypertension, diabetes, and cancer. Objective: The study determined the effects of C. xanthorrhiza extracts (ethanol and aqueous) and their constituents (curcumene and xanthorrhizol) on UDP-glucuronosyltransferase (UGT) and glutathione transferase (GST) activities. Materials and Methods: The inhibition studies were evaluated both in rat liver microsomes and in human recombinant UGT1A1 and UGT2B7 enzymes. p-nitrophenol and beetle luciferin were used as the probe substrates for UGT assay while 1-chloro-2,4-dinitrobenzene as the probe for GST assay. The concentrations of extracts studied ranged from 0.1 to 1000 μg/mL while for constituents ranged from 0.01 to 500 μM. Results: In rat liver microsomes, UGT activity was inhibited by the ethanol extract (IC50 =279.74 ± 16.33 μg/mL). Both UGT1A1 and UGT2B7 were inhibited by the ethanol and aqueous extracts with IC50 values ranging between 9.59–22.76 μg/mL and 110.71–526.65 μg/Ml, respectively. Rat liver GST and human GST Pi-1 were inhibited by ethanol and aqueous extracts, respectively (IC50 =255.00 ± 13.06 μg/mL and 580.80 ± 18.56 μg/mL). Xanthorrhizol was the better inhibitor of UGT1A1 (IC50 11.30 ± 0.27 μM) as compared to UGT2B7 while curcumene did not show any inhibition. For GST, both constituents did not show any inhibition. Conclusion: These findings suggest that C. xanthorrhiza have the potential to cause herb-drug interaction with drugs that are primarily metabolized by UGT and GST enzymes. SUMMARY Findings from this study would suggest which of Curcuma xanthorrhiza extracts and constituents that would have potential interactions with drugs which are highly metabolized by UGT and GST enzymes. Further clinical studies can then be designed if needed to evaluate the in vivo pharmacokinetic relevance of these interactions Abbreviations Used: BSA: Bovine serum albumin

  13. Distribution of genetic polymorphisms of genes encoding drug metabolizing enzymes & drug transporters - a review with Indian perspective

    PubMed Central

    Umamaheswaran, Gurusamy; Kumar, Dhakchinamoorthi Krishna; Adithan, Chandrasekaran

    2014-01-01

    Phase I and II drug metabolizing enzymes (DME) and drug transporters are involved in the absorption, distribution, metabolism as well as elimination of many therapeutic agents, toxins and various pollutants. Presence of genetic polymorphisms in genes encoding these proteins has been associated with marked inter-individual variability in their activity that could result in variation in drug response, toxicity as well as in disease predisposition. The emergent field pharmacogenetics and pharmacogenomics (PGx) is a promising discipline, as it predicts disease risk, selection of proper medication with regard to response and toxicity, and appropriate drug dosage guidance based on an individual's genetic make-up. Consequently, genetic variations are essential to understand the ethnic differences in disease occurrence, development, prognosis, therapeutic response and toxicity. For that reason, it is necessary to establish the normative frequency of these genes in a particular population before unraveling the genotype-phenotype associations. Although a fair amount of allele frequency data are available in Indian populations, the existing pharmacogenetic data have not been compiled into a database. This review was intended to compile the normative frequency distribution of the variants of genes encoding DMEs (CYP450s, TPMT, GSTs, COMT, SULT1A1, NAT2 and UGTs) and transporter proteins (MDR1, OCT1 and SLCO1B1) with Indian perspective. PMID:24604039

  14. Effects of liver diseases on drug-metabolizing enzymes: implications for drug fate alterations and nano-therapeutic openings.

    PubMed

    Lu, L; Shi, J; Li, Q; Peng, X; Dong, L; Li, Y; Dai, P; Wang, Y; Guo, E; Zhou, F; Liu, Z

    2014-01-01

    Metabolizing and eliminating toxic chemicals in the liver are key processes in the body's defense system. Drug-metabolizing enzymes (DMEs) play central roles in such processes. The activity and expression of several key DMEs are changed in various liver diseases and thus lead to significantly altered drug disposition. This phenomenon severely affects the pharmacotherapy of clinical medications in terms of the safety and efficacy of drug responses. This review highlights liver physiological functions, altered DMEs, and altered drug disposition in liver diseases. Moreover, the implications of changes in DMEs on the fate of clinically relevant drugs are also discussed. Pregnane X receptor and constitutive androstane receptor are two liver-enriched nuclear receptors originally defined as xenobiotic sensors that affect regulation of DMEs. Altered regulation of DMEs in liver diseases contributes to the development of powerful in vitro and in vivo tools to predict drug responses and options for improved drug delivery and development. Although a number of treatment drugs are available for liver diseases, they are limited by their low drug concentration in the target site, presence of side effects, and instability in the human body. The nanoparticle drug delivery system has recently attracted research attention because of its potential to offer solutions to current obstacles that involve the use of therapeutic drugs for liver diseases. Conclusively, this review aims to improve understanding on the regulation of DMEs in liver diseases and on corresponding implications in drug disposition, including novel therapeutic medications.

  15. Potential risks resulting from fruit/vegetable-drug interactions: effects on drug-metabolizing enzymes and drug transporters.

    PubMed

    Rodríguez-Fragoso, Lourdes; Martínez-Arismendi, José Luis; Orozco-Bustos, Danae; Reyes-Esparza, Jorge; Torres, Eliseo; Burchiel, Scott W

    2011-05-01

    It has been well established that complex mixtures of phytochemicals in fruits and vegetables can be beneficial for human health. Moreover, it is becoming increasingly apparent that phytochemicals can influence the pharmacological activity of drugs by modifying their absorption characteristics through interactions with drug transporters as well as drug-metabolizing enzyme systems. Such effects are more likely to occur in the intestine and liver, where high concentrations of phytochemicals may occur. Alterations in cytochrome P450 and other enzyme activities may influence the fate of drugs subject to extensive first-pass metabolism. Although numerous studies of nutrient-drug interactions have been published and systematic reviews and meta-analyses of these studies are available, no generalizations on the effect of nutrient-drug interactions on drug bioavailability are currently available. Several publications have highlighted the unintended consequences of the combined use of nutrients and drugs. Many phytochemicals have been shown to have pharmacokinetic interactions with drugs. The present review is limited to commonly consumed fruits and vegetables with significant beneficial effects as nutrients and components in folk medicine. Here, we discuss the phytochemistry and pharmacokinetic interactions of the following fruit and vegetables: grapefruit, orange, tangerine, grapes, cranberry, pomegranate, mango, guava, black raspberry, black mulberry, apple, broccoli, cauliflower, watercress, spinach, tomato, carrot, and avocado. We conclude that our knowledge of the potential risk of nutrient-drug interactions is still limited. Therefore, efforts to elucidate potential risks resulting from food-drug interactions should be intensified in order to prevent undesired and harmful clinical consequences.

  16. Murine atrial HL-1 cell line is a reliable model to study drug metabolizing enzymes in the heart.

    PubMed

    Elshenawy, Osama H; Anwar-Mohamed, Anwar; Abdelhamid, Ghada; El-Kadi, Ayman O S

    2013-04-01

    HL-1 cells are currently the only cells that spontaneously contract while maintaining a differentiated cardiac phenotype. Thus, our objective was to examine murine HL-1 cells as a new in vitro model to study drug metabolizing enzymes. We examined the expression of cytochrome P450s (Cyps), phase II enzymes, and nuclear receptors and compared their levels to mice hearts. Our results demonstrated that except for Cyp4a12 and Cyp4a14 all Cyps, phase II enzymes: glutathione-S-transferases (Gsts), heme oxygenase-1 (HO-1), and NAD(P)H: quinone oxidoreductase (Nqo1), nuclear receptors: aryl hydrocarbon receptor (AhR), constitutive androstane receptor (CAR), pregnane X receptor (PXR), and peroxisome proliferator activated receptor (PPAR-alpha) were all constitutively expressed in HL-1 cells. Cyp2b19, Cyp2c29, Cyp2c38, Cyp2c40, and Cyp4f16 mRNA levels were higher in HL-1 cells compared to mice hearts. Cyp2b9, Cyp2c44, Cyp2j9, Cyp2j11, Cyp2j13, Cyp4f13, Cyp4f15 mRNA levels were expressed to the same extent to that of mice hearts. Cyp1a1, Cyp1a2, Cyp1b1, Cyp2b10, Cyp2d10, Cyp2d22, Cyp2e1, Cyp2j5, Cyp2j6, Cyp3a11, Cyp4a10, and Cyp4f18 mRNA levels were lower in HL-1 cells compared to mice hearts. Moreover, 3-methylcholanthrene induced Cyp1a1 while fenofibrate induced Cyp2j9 and Cyp4f13 mRNA levels in HL-1 cells. Examining the metabolism of arachidonic acid (AA) by HL-1 cells, our results demonstrated that HL-1 cells metabolize AA to epoxyeicosatrienoic acids, dihydroxyeicosatrienoic acids, and 20-hydroxyeicosatetraenoic acids. In conclusion, HL-1 cells provide a valuable in vitro model to study the role of Cyps and their associated AA metabolites in addition to phase II enzymes in cardiovascular disease states.

  17. Non-alcoholic fatty liver disease (NAFLD) - pathogenesis, classification, and effect on drug metabolizing enzymes and transporters.

    PubMed

    Cobbina, Enoch; Akhlaghi, Fatemeh

    2017-03-17

    Non-alcoholic fatty liver disease (NAFLD) is a spectrum of liver disorders. It is defined by the presence of steatosis in more than 5% of hepatocytes with little or no alcohol consumption. Insulin resistance, the metabolic syndrome or type 2 diabetes and genetic variants of PNPLA3 or TM6SF2 seem to play a role in the pathogenesis of NAFLD. The pathological progression of NAFLD follows tentatively a "three-hit" process namely steatosis, lipotoxicity and inflammation. The presence of steatosis, oxidative stress and inflammatory mediators like TNF-α and IL-6 has been implicated in the alterations of nuclear factors such as CAR, PXR, PPAR-α in NAFLD. These factors may result in altered expression and activity of drug metabolizing enzymes (DMEs) or transporters. Existing evidence suggests that the effect of NAFLD on CYP3A4, CYP2E1 and MRP3 is more consistent across rodent and human studies. CYP3A4 activity is down-regulated in NASH whereas the activity of CYP2E1 and the efflux transporter MRP3 is up-regulated. However, it is not clear how the majority of CYPs, UGTs, SULTs and transporters are influenced by NAFLD either in vivo or in vitro. The alterations associated with NAFLD could be a potential source of drug variability in patients and could have serious implications for the safety and efficacy of xenobiotics. In this review, we summarize the effects of NAFLD on the regulation, expression and activity of major DMEs and transporters. We also discuss the potential mechanisms underlying these alterations.

  18. An enhanced in vivo stable isotope labeling by amino acids in cell culture (SILAC) model for quantification of drug metabolism enzymes.

    PubMed

    MacLeod, A Kenneth; Fallon, Padraic G; Sharp, Sheila; Henderson, Colin J; Wolf, C Roland; Huang, Jeffrey T-J

    2015-03-01

    Many of the enzymes involved in xenobiotic metabolism are maintained at a low basal level and are only synthesized in response to activation of upstream sensor/effector proteins. This induction can have implications in a variety of contexts, particularly during the study of the pharmacokinetics, pharmacodynamics, and drug-drug interaction profile of a candidate therapeutic compound. Previously, we combined in vivo SILAC material with a targeted high resolution single ion monitoring (tHR/SIM) LC-MS/MS approach for quantification of 197 peptide pairs, representing 51 drug metabolism enzymes (DME), in mouse liver. However, as important enzymes (for example, cytochromes P450 (Cyp) of the 1a and 2b subfamilies) are maintained at low or undetectable levels in the liver of unstimulated metabolically labeled mice, quantification of these proteins was unreliable. In the present study, we induced DME expression in labeled mice through synchronous ligand-mediated activation of multiple upstream nuclear receptors, thereby enhancing signals for proteins including Cyps 1a, 2a, 2b, 2c, and 3a. With this enhancement, 115 unique, lysine-containing, Cyp-derived peptides were detected in the liver of a single animal, as opposed to 56 in a pooled sample from three uninduced animals. A total of 386 peptide pairs were quantified by tHR/SIM, representing 68 Phase I, 30 Phase II, and eight control proteins. This method was employed to quantify changes in DME expression in the hepatic cytochrome P450 reductase null (HRN) mouse. We observed compensatory induction of several enzymes, including Cyps 2b10, 2c29, 2c37, 2c54, 2c55, 2e1, 3a11, and 3a13, carboxylesterase (Ces) 2a, and glutathione S-transferases (Gst) m2 and m3, along with down-regulation of hydroxysteroid dehydrogenases (Hsd) 11b1 and 17b6. Using DME-enhanced in vivo SILAC material with tHR/SIM, therefore, permits the robust analysis of multiple DME of importance to xenobiotic metabolism, with improved utility for the study of

  19. Hepatic cytochrome P450 3A drug metabolism is reduced in cancer patients who have an acute-phase response

    PubMed Central

    Rivory, L P; Slaviero, K A; Clarke, S J

    2002-01-01

    Inflammatory disease states (infection, arthritis) are associated with reduced drug oxidation by the cytochrome P450 3A system. Many chemotherapy agents are metabolised through this pathway, and disease may therefore influence inter-individual differences in drug pharmacokinetics. The purpose of this study was to assess cytochrome P450 3A function in patients with advanced cancer, and its relation to the acute-phase response. We evaluated hepatic cytochrome P450 3A function in 40 patients with advanced cancer using the erythromycin breath test. Both the traditional C20min measure and the recently proposed 1/TMAX values were estimated. The marker of acute-phase response, C-reactive protein and the pro-inflammatory cytokines IL-6, IL-1β, TNFα and IL-8 were measured in serum or plasma at baseline. Cancer patients with an acute phase response (C-reactive protein >10 mg l−1, n=26) had reduced metabolism as measured with the erythromycin breath test 1/TMAX (Kruskal–Wallis Anova, P=0.0062) as compared to controls (C-reactive protein ⩽10 mg l−1, n=14). Indeed, metabolism was significantly associated with C-reactive protein over the whole concentration range of this acute-phase marker (r=−0.64, Spearman Rank Correlation, P<0.00001). C-reactive protein serum levels were significantly correlated with those of IL-6 (Spearman coefficient=0.58, P<0.0003). The reduction in cytochrome P450 3A function with acute-phase reaction was independent of the tumour type and C-reactive protein elevation was associated with poor performance status. This indicates that the sub-group of cancer patients with significant acute-phase response have compromised drug metabolism, which may have implications for the safety of chemotherapy in this population. British Journal of Cancer (2002) 87, 277–280. doi:10.1038/sj.bjc.6600448 www.bjcancer.com © 2002 Cancer Research UK PMID:12177794

  20. Effect of Intestinal Flora on Protein Expression of Drug-Metabolizing Enzymes and Transporters in the Liver and Kidney of Germ-Free and Antibiotics-Treated Mice.

    PubMed

    Kuno, Takuya; Hirayama-Kurogi, Mio; Ito, Shingo; Ohtsuki, Sumio

    2016-08-01

    Dysbiosis (alteration of intestinal flora) is associated with various host physiologies, including diseases. The purpose of this study was to clarify the effect of dysbiosis on protein expression levels in mouse liver and kidney by quantitative proteomic analysis, focusing in particular on drug-metabolizing enzymes and transporters in order to investigate the potential impact of dysbiosis on drug pharmacokinetics. Germ-free (GF) mice and antibiotics-treated mice were used as dysbiosis models. Expression levels of 825 and 357 proteins were significantly changed in the liver and kidney, respectively, of GF mice (vs specific-pathogen-free mice), while 306 and 178 proteins, respectively, were changed in antibiotics-treated mice (vs vehicle controls). Among them, 52 and 16 drug-metabolizing enzyme and transporter proteins were significantly changed in the liver and kidney, respectively, of GF mice, while 25 and 8, respectively were changed in antibiotics-treated mice. Expression of mitochondrial proteins was also changed in the liver and kidney of both model mice. In GF mice, Oatp1a1 was decreased in both the liver and kidney, while Sult1a1 and two Cyp enzymes were increased and Gstp1, four Cyp enzymes, three Ces enzymes, Bcrp1, and Oct1 were decreased in the liver. In antibiotics-treated mice, Cyp51a1 was increased and three Cyp enzymes, Bcrp1, and Bsep were decreased in the liver. Notably, the expression of Cyp2b10 and Cyp3a11 was greatly decreased in the liver of both models. Cyp2b activity in the liver microsomal fraction was also decreased. Our results indicate that dysbiosis changes the protein expression of multiple drug-metabolizing enzymes and transporters in the liver and kidney and may alter pharmacokinetics in the host.

  1. Analysis of gene expression changes of drug metabolizing enzymes in the livers of F344 rats following oral treatment with kava extract.

    PubMed

    Guo, Lei; Li, Quanzhen; Xia, Qingsu; Dial, Stacey; Chan, Po-Chuen; Fu, Peter

    2009-02-01

    The association of kava product use with liver-related risks has prompted regulatory action in many countries. We studied the changes in gene expression of drug metabolizing enzymes in the livers of Fischer 344 male rats administered kava extract by gavage for 14 weeks. Analysis of 22,226 genes revealed that there were 14, 41, 110, 386, and 916 genes significantly changed in the 0.125, 0.25, 0.5, 1.0, and 2.0 g/kg treatment groups, respectively. There were 16 drug metabolizing genes altered in all three high-dose treatment groups, among which seven genes belong to cytochrome P450 isozymes. While gene expression of Cyp1a1, 1a2, 2c6, 3a1, and 3a3 increased; Cyp 2c23 and 2c40 decreased, all in a dose-dependent manner. Real-time PCR analyses of several genes verified these results. Our results indicate that kava extract can significantly modulate drug metabolizing enzymes, particularly the CYP isozymes, which could cause herb-drug interactions and may potentially lead to hepatotoxicity.

  2. Schisandra chinensis regulates drug metabolizing enzymes and drug transporters via activation of Nrf2-mediated signaling pathway

    PubMed Central

    He, Jin-Lian; Zhou, Zhi-Wei; Yin, Juan-Juan; He, Chang-Qiang; Zhou, Shu-Feng; Yu, Yang

    2015-01-01

    Drug metabolizing enzymes (DMEs) and drug transporters are regulated via epigenetic, transcriptional, posttranscriptional, and translational and posttranslational modifications. Phase I and II DMEs and drug transporters play an important role in the disposition and detoxification of a large number of endogenous and exogenous compounds. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a critical regulator of a variety of important cytoprotective genes that are involved in disposition and detoxification of xenobiotics. Schisandra chinensis (SC) is a commonly used traditional Chinese herbal medicine that has been primarily used to protect the liver because of its potent antioxidative and anti-inflammatory activities. SC can modulate some DMEs and drug transporters, but the underlying mechanisms are unclear. In this study, we aimed to explore the role of Nrf2 in the regulatory effect of SC extract (SCE) on selected DMEs and drug transporters in human hepatocellular liver carcinoma cell line (HepG2) cells. The results showed that SCE, schisandrin A, and schisandrin B significantly increased the expression of NAD(P)H: Nicotinamide Adenine Dinucleotide Phosphate-oxidase or:quinone oxidoreductase 1, heme oxygenase-1, glutamate–cysteine ligase, and glutathione S-transferase A4 at both transcriptional and posttranscriptional levels. Incubation of HepG2 cells with SCE resulted in a significant increase in the intracellular level of glutathione and total glutathione S-transferase content. SCE significantly elevated the messenger ribonucleic acid and protein levels of P-glycoprotein and multidrug resistance-associated protein 2 and 4, whereas the expression of organic anion transporting peptide 1A2 and 1B1 was significantly downregulated by SCE. Knockdown of Nrf2 by small interfering ribonucleic acid attenuated the regulatory effect of SCE on these DMEs and drug transporters. SCE significantly upregulated Nrf2 and promoted the translocation of Nrf2 from cytoplasm to

  3. Functional proteomic analysis of corticosteroid pharmacodynamics in rat liver: Relationship to hepatic stress, signaling, energy regulation, and drug metabolism.

    PubMed

    Ayyar, Vivaswath S; Almon, Richard R; DuBois, Debra C; Sukumaran, Siddharth; Qu, Jun; Jusko, William J

    2017-03-14

    Corticosteroids (CS) are anti-inflammatory agents that cause extensive pharmacogenomic and proteomic changes in multiple tissues. An understanding of the proteome-wide effects of CS in liver and its relationships to altered hepatic and systemic physiology remains incomplete. Here, we report the application of a functional pharmacoproteomic approach to gain integrated insight into the complex nature of CS responses in liver in vivo. An in-depth functional analysis was performed using rich pharmacodynamic (temporal-based) proteomic data measured over 66h in rat liver following a single dose of methylprednisolone (MPL). Data mining identified 451 differentially regulated proteins. These proteins were analyzed on the basis of temporal regulation, cellular localization, and literature-mined functional information. Of the 451 proteins, 378 were clustered into six functional groups based on major clinically-relevant effects of CS in liver. MPL-responsive proteins were highly localized in the mitochondria (20%) and cytosol (24%). Interestingly, several proteins were related to hepatic stress and signaling processes, which appear to be involved in secondary signaling cascades and in protecting the liver from CS-induced oxidative damage. Consistent with known adverse metabolic effects of CS, several rate-controlling enzymes involved in amino acid metabolism, gluconeogenesis, and fatty-acid metabolism were altered by MPL. In addition, proteins involved in the metabolism of endogenous compounds, xenobiotics, and therapeutic drugs including cytochrome P450 and Phase-II enzymes were differentially regulated. Proteins related to the inflammatory acute-phase response were up-regulated in response to MPL. Functionally-similar proteins showed large diversity in their temporal profiles, indicating complex mechanisms of regulation by CS.

  4. Stereoselectivity in drug metabolism.

    PubMed

    Lu, Hong

    2007-04-01

    Many chiral drugs are used as their racemic mixtures in clinical practice. Two enantiomers of a chiral drug generally differ in pharmacodynamic and/or pharmacokinetic properties as a consequence of the stereoselective interaction with optically active biological macromolecules. Thus, a stereospecific assay to discriminate between enantiomers is required in order to relate plasma concentrations to pharmacological effect of a chiral drug. Stereoselective metabolism of drugs is most commonly the major contributing factor to stereoselectivity in pharmacokinetics. Metabolizing enzymes often display a preference for one enantiomer of a chiral drug over the other, resulting in enantioselectivity. The structural characteristics of enzymes dictate the enantiomeric discrimination associated with the metabolism of chiral drugs. The stereoselectivity can, therefore, be viewed as the physical property characteristic that phenotypes the enzyme. This review provides a comprehensive appraisal of stereochemical aspects of drug metabolism (i.e., enantioselective metabolism and first-pass effect, enzyme-selective inhibition or induction and drug interaction, species differences and polymorphic metabolism).

  5. Impact of quercetin-induced changes in drug-metabolizing enzyme and transporter expression on the pharmacokinetics of cyclosporine in rats

    PubMed Central

    Liu, Yani; Luo, Xiaomei; Yang, Chunxiao; Yang, Tingyu; Zhou, Jiali; Shi, Shaojun

    2016-01-01

    The aim of the present study was to evaluate whether quercetin (Que) modulates the mRNA and protein expression levels of drug-metabolizing enzymes (DMEs) and drug transporters (DTs) in the small intestine and liver, and thus modifies the pharmacokinetic profile of cyclosporine (CsA) in rats. This two-part study evaluated the pharmacokinetic profiles of CsA in the presence or absence of Que (experiment I) and the involvement of DMEs and DTs (experiment II). In experiment I, 24 rats received single-dose CsA (10 mg/kg) on day 1, single-dose Que (25, 50 and 100 mg/kg/day; eight rats in each group) on days 3–8, and concomitant CsA/Que on day 9. In experiment II, the mRNA and protein expression levels of cytochrome P (CYP)3A1, CYP3A2, UDP glucuronosyltransferase family 1 member A complex locus, organic anion-transporting polypeptide (OATP)2B1, OATP1B2, P-glycoprotein, breast cancer resistance protein, and multidrug resistance-associated protein 2 in the small intestine and liver of rats were analyzed following oral administration of Que at 25, 50 and 100 mg/kg in the presence or absence of CsA (10 mg/kg) for seven consecutive days. Co-administration of Que (25,50 and 100 mg/kg) decreased the maximum serum concentration of CsA by 46, 50 and 47% in a dose-independent manner. In addition, the area under the curve to the last measurable concentration and area under the curve to infinite time were decreased, by 21 and 16%, 30 and 33%, and 33 and 34% (P<0.01), respectively. However, the mRNA and protein expression levels of the above-mentioned DMEs and DTs were inhibited by Que in a dose-dependent manner (P<0.01) to a similar extent in the small intestine and liver. It was demonstrated that Que was able to reduce the bioavailability of CsA following multiple concomitant doses in rats. Overlapping modulation of intestinal and hepatic DMEs and DTs, as well as the DME-DT interplay are potential explanations for these observations. PMID:27510982

  6. The effects of estrus cycle on drug metabolism in the rat.

    PubMed

    Brandstetter, Y; Kaplanski, J; Leibson, V; Ben-Zvi, Z

    1986-01-01

    The effect of the female rat estral cycle on microsomal drug metabolism in-vivo and in-vitro has been studied. Two microsomal enzymes, aminopyrine-N-demethylase and aniline hydroxylase showed a greater specific activity (p less than 0.01) in the diestrus phase of the estral cycle while the oxidative enzyme aryl hydrocarbon hydroxylase and the conjugative enzyme, glucuronyl transferase, were not affected. In vivo studies which included theophylline and antipyrine metabolism, and hexobarbital sleeping times showed no difference between the different phases of the estral cycle. Conflicting evidence about the effect of steroid sex hormones on hepatic drug metabolism is discussed.

  7. A microscale in vitro physiological model of the liver: predictive screens for drug metabolism and enzyme induction.

    PubMed

    Sivaraman, A; Leach, J K; Townsend, S; Iida, T; Hogan, B J; Stolz, D B; Fry, R; Samson, L D; Tannenbaum, S R; Griffith, L G

    2005-12-01

    In vitro models of the liver using isolated primary hepatocytes have been used as screens for measuring the metabolism, toxicity and efficacy of xenobiotics, for studying hepatocyte proliferation, and as bioartificial liver support systems. Yet, primary isolated hepatocytes rapidly lose liver specific functions when maintained under standard in vitro cell culture conditions. Many modifications to conventional culture methods have been developed to foster retention of hepatocyte function. Still, not all of the important functions -- especially the biotransformation functions of the liver -- can as yet be replicated at desired levels, prompting continued development of new culture systems. In the first part of this article, we review primary hepatocyte in vitro systems used in metabolism and enzyme induction studies. We then describe a scalable microreactor system that fosters development of 3D-perfused micro-tissue units and show that primary rat cells cultured in this system are substantially closer to native liver compared to cells cultured by other in vitro methods, as assessed by a broad spectrum of gene expression, protein expression and biochemical activity metrics. These results provide a foundation for extension of this culture model to other applications in drug discovery -- as a model to study drug-drug interactions, as a model for the assessment of acute and chronic liver toxicity arising from exposure to drugs or environmental agents; and as a disease model for the study of viral hepatitis infection and cancer metastasis.

  8. Garlic attenuates chrysotile-mediated pulmonary toxicity in rats by altering the phase I and phase II drug metabolizing enzyme system.

    PubMed

    Ameen, Mohamed; Musthapa, M Syed; Abidi, Parveen; Ahmad, Iqbal; Rahman, Qamar

    2003-01-01

    Asbestos and its carcinogenic properties have been extensively documented. Asbestos exposure induces diverse cellular events associated with lung injury. Previously, we have shown that treatment with chrysotile shows significant alteration in phase I and phase II drug metabolizing enzyme system. In this study we have examined some potential mechanisms by which garlic treatment attenuates chrysotile-mediated pulmonary toxicity in rat. Female Wistar rats received an intratracheal instillation of 5 mg chrysotile (0.5 mL saline) as well as intragastric garlic treatment (1% body weight (v/w); 6 days per week). Effect of garlic treatment was evaluated after 1, 15, 30, 90, and 180 days by assaying aryl hydrocarbon hydroxylase (AHH), glutathione (GSH), glutathione S-transferase (GST), and production of thiobarbituric acid reactive substances (TBARS) in rat lung microsome. The results showed that AHH and TBARS formation were significantly reduced at day 90 and day 180 in chrysotile treated garlic cofed rats; GSH recovered 15 days later to the near normal level and GST elevated significantly after treatment of garlic as compared to chrysotile alone treated rat lung microsome. The data obtained shows that inhibition of AHH activity and induction of GST activity could be contributing factor in chrysotile-mediated pulmonary toxicity in garlic cofed rats. However, recovery of GSH and inhibition of TBARS formation by garlic and its constituent(s) showed that garlic may give protection by altering the drug metabolizing enzyme system.

  9. Differences in the drug-metabolizing enzyme activities among fish and bivalves living in waters near industrial and non-industrial areas

    SciTech Connect

    Oshima, Y.; Kobayashi, K.; Hidaka, C.; Izu, S.; Imada, N. )

    1994-07-01

    Fish and shellfishes, living in coastal areas receiving agricultural, industrial and domestic wastewaters, have been exposed to various chemicals. Identifing the various harmful chemicals in the environments and accumulated in aquatic organisms is difficult. Even if concentrations of pollutants are low so that no mortality of fish and shellfishes occurs, the pollutants may affect the biochemistry and physiology of aquatic organisms. Activities of some drug-metabolizing enzymes, especially the cytochrome P-450 dependent monooxygenase (MO) in fish livers, increase when fish are exposed to environmental pollutants such as polycyclic aromatic hydrocarbons, halogenated organic chemicals. However, most studies have been done on the field evaluation only by MO induction in fish as a monitor for marine pollution with crude-oil and halogenated organic compounds, without regard for other chemicals. In a previous paper, the activity of benzo(a)pyrene hydroxylase (AHH) was induced by 22 times at 2-wk, although the cytochrome P-450 content increased only twice. Activity of phenol-sulfate transferase in the mid-gut gland of short-necked clam was induced by exposure to some phenolic compounds, especially pentachlorophenol (PCP), resulting in the increase of the enzyme activity by approximately 7 times the control after 5 wk exposure. Induced activity was maintained at least for 3 wk, even after the clam had been transferred to running clean sea water, although PCP accumulated in its body is rapidly excreted. Although the activity of this enzyme in the clam is easily induced by exposure to phenols, the induction of this enzyme activity in fish is very low as compared with that of clam. This paper examines the activities of drug-metabolizing enzymes of fish and bivalves living in waters near industrial and non-industrial areas to elucidate the applicability of the sulfate transferase activity in bivalves as a monitor for marine pollution, as well as the MO activity in fish.

  10. High-quality genotyping data from formalin-fixed, paraffin-embedded tissue on the drug metabolizing enzymes and transporters plus array.

    PubMed

    Vos, Hanneke I; van der Straaten, Tahar; Coenen, Marieke J H; Flucke, Uta; te Loo, D Maroeska W M; Guchelaar, Henk-Jan

    2015-01-01

    The Affymetrix Drug Metabolizing Enzymes and Transporters (DMET) Plus array covers 1936 markers in 231 genes involved in drug metabolism and transport. Blood- and saliva-derived DNA works well on the DMET array, but the utility of DNA from FFPE tissue has not been reported for this array. As the ability to use DNA from FFPE tissue on the array could open the potential for large retrospective sample collections, we examined the performance and reliability of FFPE-derived DNA on the DMET Plus array. Germline DNA isolated from archived normal FFPE tissue blocks stored for 3 to 19 years and matched blood or saliva from 16 patients with osteosarcoma were genotyped on the DMET Plus array. Concordance was assessed by calculating agreement and the κ-statistic. We observed high call rates for both the blood- or saliva-derived DNA samples (99.4%) and the FFPE-derived DNA samples (98.9%). Moreover, the concordance among the 16 blood- or saliva-derived DNA and FFPE DNA pairs was high (97.4%, κ = 0.915). This is the first study showing that DNA from normal FFPE tissue provides accurate and reliable genotypes on the DMET Plus array compared with blood- or saliva-derived DNA. This finding provides an opportunity for pharmacogenetic studies in diseases with high mortality rates and prevents a bias in studies where otherwise only alive patients can be included.

  11. Drug metabolizing enzymes and transporters mRNA in peripheral blood mononuclear cells of healthy subjects: biological variations and importance of pre-analytical steps.

    PubMed

    Siest, Gérard; Jeannesson, Elise; Marteau, Jean-Brice; Samara, Anastasia; Pfister, Michèle; Visvikis-Siest, Sophie

    2009-05-01

    Quantification in peripheral blood mononuclear cells of mRNA of drug metabolizing enzymes or drug targets could give interesting, new information in the field of pharmacogenomics and molecular mechanisms. However, for the interpretation of these data, it is necessary to know mRNA biological variations. In this review, we propose a strategy based on the production and interpretation of clinical chemistry reference values. We discuss the concept of reference values; the necessity to master pre-analytical variations of CYP and ABC transporters; the choice of the analytical methods and of the reference genes; and finally the biological variations themselves. In particular, we focus on the importance of considering homogeneity for age, sex, degree of adiposity, tobacco and alcohol intake, food habits, and drug consumption, including their inductive effects, at the phase of subject recruitment. All this information is useful to define the partition and exclusion factors to obtain mRNA reference limits.

  12. Pharmacogenetics of P450 oxidoreductase: implications in drug metabolism and therapy.

    PubMed

    Hu, Lei; Zhuo, Wei; He, Yi-Jing; Zhou, Hong-Hao; Fan, Lan

    2012-11-01

    The redox reaction of cytochrome P450 enzymes (CYP) is an important physiological and biochemical reaction in the human body, as it is involved in the oxidative metabolism of both endogenous and exogenous substrates. Cytochrome P450 oxidoreductase (POR) is the only obligate electron donor for all of the hepatic microsomal CYP enzymes. It plays a crucial role in drug metabolism and treatment by not only acting as an electron donor involved in drug metabolism mediated by CYP enzymes but also by directly inducing the transformation of some antitumor precursors. Studies have found that the gene encoding human POR is highly polymorphic, which is of considerable clinical significance as it affects the metabolism and curative effects of clinically used drugs. This review aims to discuss the effect of POR and its genetic polymorphisms on drug metabolism and therapy, as well as the potential mechanisms of POR pharmacogenetics.

  13. In vitro metabolic stability and intestinal transport of P57AS3 (P57) from Hoodia gordonii and its interaction with drug metabolizing enzymes.

    PubMed

    Madgula, Vamsi L M; Avula, Bharathi; Pawar, Rahul S; Shukla, Yatin J; Khan, Ikhlas A; Walker, Larry A; Khan, Shabana I

    2008-08-01

    Hoodia gordonii, a succulent cactus-like plant growing in South Africa, has been used in traditional medicine for its appetite suppressant properties. Its use as a dietary supplement to promote weight loss has recently gained popularity. An oxypregnane steroidal glycoside P57AS3 (P57) is reported to be the active constituent of the sap extract responsible for anorexigenic activity. No information is available about its metabolic stability, intestinal transport and interaction with drug metabolizing enzymes. In the present investigation, the metabolic stability of P57 in human liver microsomes and its interaction with drug metabolizing enzymes (CYP1A2, 2C9, 3A4 and 2D6) were determined. Intestinal transport of P57 was studied in the Caco-2 cell model of intestinal transport and absorption. P57 was metabolically stable in the presence of human liver microsomes. The compound inhibited CYP3A4 activity with an IC50 value of 45 microM, whereas the activity of CYP 1A2, 2C9 and 2D6 was not inhibited. In the Caco-2 model, P57 exhibited a higher transport in the secretory direction than in the absorptive direction with efflux ratios of 3.1 and 3.8 at 100 and 200 microM, respectively. The efflux was inhibited by selective inhibitors of multidrug resistance associated proteins MRP1/MRP2 (MK-571) and P-gp (verapamil). In conclusion, intestinal transport of P57 was mediated by P-gp and MRP transporters. The compound was metabolically stable and showed weak inhibition of CYP 3A4.

  14. Correlation of intrinsic in vitro and in vivo clearance for drugs metabolized by hepatic UDP-glucuronosyltransferases in rats.

    PubMed

    Nakamori, Fumihiro; Naritomi, Yoichi; Furutani, Masako; Takamura, Fujiko; Miura, Hiroya; Murai, Hidetsugu; Terashita, Shigeyuki; Teramura, Toshio

    2011-01-01

    A method for quantitatively predicting the hepatic clearance of drugs by UDP-glucuronosyltransferases (UGTs) from in vitro data has not yet been established. We examined the relationship between in vitro and in vivo intrinsic clearance by rat hepatic UGTs using 10 drugs. For these 10 drugs, the in vitro intrinsic clearance by UGTs (CL(int, in vitro)) measured using alamethicin-activated rat liver microsomes was in the range 0.10-4500 ml/min/kg. Microsomal binding (f(u, mic)) was determined to be in the range 0.29-0.95 and the unbound intrinsic clearance (CL(uint, in vitro)) to be in the range 0.11-9600 ml/min/kg. The contribution of rat hepatic glucuronidation to drug elimination was 12.0%-76.6% and in vivo intrinsic clearance by UGTs was 5.7-9000 ml/min/kg. To evaluate the discrepancy between the in vitro and in vivo values, a scaling factor was calculated (CL(int, in vivo)/CL(int, in vitro)); the values were found to be in the range 0.89-110. The average fold error of the scaling factor values incorporating f(u, mic) was closer to unity than that without f(u, mic). The scaling factor values incorporating f(u, mic) were <10 in 8/10 drugs and <2 in 6/10 drugs, indicating a small discrepancy between in vitro and in vivo values. Thus, using alamethicin-activated liver microsomes, incorporating f(u, mic) into CL(int, in vitro), and considering the contribution of glucuronidation may enable us to quantitatively predict in vivo hepatic glucuronidation from in vitro data.

  15. Summary of Information on the Effects of Ionizing and Non-ionizing Radiation on Cytochrome P450 and Other Drug Metabolizing Enzymes and Transporters

    PubMed Central

    Rendic, Slobodan; Guengerich, F. Peter

    2014-01-01

    The present paper is an update of data on the effects of ionizing radiation (γ-rays, X-rays, high energy UV, fast neutron) caused by environmental pollution or clinical treatments and the effects of non-ionizing radiation (low energy UV) on the expression and/or activity of drug metabolism (e.g., cytochrome P450,, glutathione transferase), enzymes involved in oxidative stress (e.g., peroxidases, catalase,, aconitase, superoxide dismutase), and transporters. The data are presented in tabular form (Tables 1–3) and are a continuation of previously published summaries on the effects of drugs and other chemicals on cytochrome P450 enzymes (Rendic, S.; Di Carlo, F. Drug Metab. Rev., 1997, 29 (1–2), 413–580, Rendic, S. Drug Metab. Rev., 2002, 34 (1–2), 83–448) and of the data on the effects of diseases and environmental factors on the expression and/or activity of human cytochrome P450 enzymes and transporters (Guengerich, F.P.; Rendic, S. Curr. Drug Metab., 2010, 11(1), 1–3, Rendic, S.; Guengerich, F.P. Curr. Drug Metab., 2010, 11 (1), 4–84). The collective information is as presented by the cited author(s) in cases where several references are cited the latest published information is included. Remarks and conclusions suggesting clinically important impacts are highlighted, followed by discussion of the major findings. The searchable database is available as an Excel file (for information about file availability contact the corresponding author). PMID:22571481

  16. Carboxymefloquine, the major metabolite of the antimalarial drug mefloquine, induces drug-metabolizing enzyme and transporter expression by activation of pregnane X receptor.

    PubMed

    Piedade, Rita; Traub, Stefanie; Bitter, Andreas; Nüssler, Andreas K; Gil, José P; Schwab, Matthias; Burk, Oliver

    2015-01-01

    Malaria patients are frequently coinfected with HIV and mycobacteria causing tuberculosis, which increases the use of coadministered drugs and thereby enhances the risk of pharmacokinetic drug-drug interactions. Activation of the pregnane X receptor (PXR) by xenobiotics, which include many drugs, induces drug metabolism and transport, thereby resulting in possible attenuation or loss of the therapeutic responses to the drugs being coadministered. While several artemisinin-type antimalarial drugs have been shown to activate PXR, data on nonartemisinin-type antimalarials are still missing. Therefore, this study aimed to elucidate the potential of nonartemisinin antimalarial drugs and drug metabolites to activate PXR. We screened 16 clinically used antimalarial drugs and six major drug metabolites for binding to PXR using the two-hybrid PXR ligand binding domain assembly assay; this identified carboxymefloquine, the major and pharmacologically inactive metabolite of the antimalarial drug mefloquine, as a potential PXR ligand. Two-hybrid PXR-coactivator and -corepressor interaction assays and PXR-dependent promoter reporter gene assays confirmed carboxymefloquine to be a novel PXR agonist which specifically activated the human receptor. In the PXR-expressing intestinal LS174T cells and in primary human hepatocytes, carboxymefloquine induced the expression of drug-metabolizing enzymes and transporters on the mRNA and protein levels. The crucial role of PXR for the carboxymefloquine-dependent induction of gene expression was confirmed by small interfering RNA (siRNA)-mediated knockdown of the receptor. Thus, the clinical use of mefloquine may result in pharmacokinetic drug-drug interactions by means of its metabolite carboxymefloquine. Whether these in vitro findings are of in vivo relevance has to be addressed in future clinical drug-drug interaction studies.

  17. Emerging roles for brain drug-metabolizing cytochrome P450 enzymes in neuropsychiatric conditions and responses to drugs.

    PubMed

    Toselli, Francesca; Dodd, Peter R; Gillam, Elizabeth M J

    2016-08-01

    P450s in the human brain were originally considered unlikely to contribute significantly to the clearance of drugs and other xenobiotic chemicals, since their overall expression was a small fraction of that found in the liver. However, it is now recognized that P450s play substantial roles in the metabolism of both exogenous and endogenous chemicals in the brain, but in a highly cell type- and region-specific manner, in line with the greater functional heterogeneity of the brain compared to the liver. Studies of brain P450 expression and the characterization of the catalytic activity of specific forms expressed as recombinant enzymes have suggested possible roles for xenobiotic-metabolizing P450s in the brain. It is now possible to confirm these roles through the use of intracerebroventricular administration of selective P450 inhibitors in animal models, coupled with brain sampling techniques to measure drug concentrations in vivo, and modern neuroimaging techniques. The purpose of this review is to discuss the evidence behind the functional importance of P450s from the "xenobiotic-metabolizing" families, CYP1, CYP2 and CYP3 in the brain. Approaches used to define the quantitative and qualitative significance of these P450s in determining tissue-specific levels of xenobiotics in brain will be considered. Finally, the possible roles of these enzymes in brain biochemistry will be examined in light of the demonstrated activity of these enzymes in vitro and the association of particular P450 forms with disease states.

  18. Pharmacokinetic changes in drugs during protein-calorie malnutrition: correlation between drug metabolism and hepatic microsomal cytochrome P450 isozymes.

    PubMed

    Lee, Joo Hyun; Suh, Ok Kyung; Lee, Myung Gull

    2004-07-01

    The rats with protein-calorie malnutrition (PCM, 5% casein diet for a period of 4-week) were reported to exhibit 60 and 80% suppression in the hepatic microsomal cytochrome P450 (CYP) 1A2 and CYP2C11 levels, respectively, and 40-50% decreases in CYP2E1 and CYP3A1/2 levels compared to control (23% casein diet for a period of 4-week) based on Western blot analysis. In addition, Northern blot analysis showed that CYP1A2, CYP2E1, CYP2C11, and CYP3A1/2 mRNAs decreased in the state of PCM as well. Hence, pharmacokinetic changes of the drugs in rats with PCM [especially the area under the plasma concentration-time curve from time zero to time infinity (AUC) changes of metabolite(s)] reported from literatures were tried to explain in terms of CYP isozyme changes in the rats. Otherwise, the time-averaged nonrenal clearance (CL NR) of parent drug was compared. Pharmacokinetic changes of the drugs in other types of malnutritional state, such as kwashiorkor and marasmus, in both human and animal models were also compared. The drugs reviewed are as follows: diuretics, antibiotics, anticancer agents, antiepileptics, antiarrythmics, analgesics, xanthines, antimalarials, and miscellaneous.

  19. Evolution of a major drug metabolizing enzyme defect in the domestic cat and other felidae: phylogenetic timing and the role of hypercarnivory.

    PubMed

    Shrestha, Binu; Reed, J Michael; Starks, Philip T; Kaufman, Gretchen E; Goldstone, Jared V; Roelke, Melody E; O'Brien, Stephen J; Koepfli, Klaus-Peter; Frank, Laurence G; Court, Michael H

    2011-03-28

    The domestic cat (Felis catus) shows remarkable sensitivity to the adverse effects of phenolic drugs, including acetaminophen and aspirin, as well as structurally-related toxicants found in the diet and environment. This idiosyncrasy results from pseudogenization of the gene encoding UDP-glucuronosyltransferase (UGT) 1A6, the major species-conserved phenol detoxification enzyme. Here, we established the phylogenetic timing of disruptive UGT1A6 mutations and explored the hypothesis that gene inactivation in cats was enabled by minimal exposure to plant-derived toxicants. Fixation of the UGT1A6 pseudogene was estimated to have occurred between 35 and 11 million years ago with all extant Felidae having dysfunctional UGT1A6. Out of 22 additional taxa sampled, representative of most Carnivora families, only brown hyena (Parahyaena brunnea) and northern elephant seal (Mirounga angustirostris) showed inactivating UGT1A6 mutations. A comprehensive literature review of the natural diet of the sampled taxa indicated that all species with defective UGT1A6 were hypercarnivores (>70% dietary animal matter). Furthermore those species with UGT1A6 defects showed evidence for reduced amino acid constraint (increased dN/dS ratios approaching the neutral selection value of 1.0) as compared with species with intact UGT1A6. In contrast, there was no evidence for reduced amino acid constraint for these same species within UGT1A1, the gene encoding the enzyme responsible for detoxification of endogenously generated bilirubin. Our results provide the first evidence suggesting that diet may have played a permissive role in the devolution of a mammalian drug metabolizing enzyme. Further work is needed to establish whether these preliminary findings can be generalized to all Carnivora.

  20. Evolution of a Major Drug Metabolizing Enzyme Defect in the Domestic Cat and Other Felidae: Phylogenetic Timing and the Role of Hypercarnivory

    PubMed Central

    Shrestha, Binu; Reed, J. Michael; Starks, Philip T.; Kaufman, Gretchen E.; Goldstone, Jared V.; Roelke, Melody E.; O'Brien, Stephen J.; Koepfli, Klaus-Peter; Frank, Laurence G.; Court, Michael H.

    2011-01-01

    The domestic cat (Felis catus) shows remarkable sensitivity to the adverse effects of phenolic drugs, including acetaminophen and aspirin, as well as structurally-related toxicants found in the diet and environment. This idiosyncrasy results from pseudogenization of the gene encoding UDP-glucuronosyltransferase (UGT) 1A6, the major species-conserved phenol detoxification enzyme. Here, we established the phylogenetic timing of disruptive UGT1A6 mutations and explored the hypothesis that gene inactivation in cats was enabled by minimal exposure to plant-derived toxicants. Fixation of the UGT1A6 pseudogene was estimated to have occurred between 35 and 11 million years ago with all extant Felidae having dysfunctional UGT1A6. Out of 22 additional taxa sampled, representative of most Carnivora families, only brown hyena (Parahyaena brunnea) and northern elephant seal (Mirounga angustirostris) showed inactivating UGT1A6 mutations. A comprehensive literature review of the natural diet of the sampled taxa indicated that all species with defective UGT1A6 were hypercarnivores (>70% dietary animal matter). Furthermore those species with UGT1A6 defects showed evidence for reduced amino acid constraint (increased dN/dS ratios approaching the neutral selection value of 1.0) as compared with species with intact UGT1A6. In contrast, there was no evidence for reduced amino acid constraint for these same species within UGT1A1, the gene encoding the enzyme responsible for detoxification of endogenously generated bilirubin. Our results provide the first evidence suggesting that diet may have played a permissive role in the devolution of a mammalian drug metabolizing enzyme. Further work is needed to establish whether these preliminary findings can be generalized to all Carnivora. PMID:21464924

  1. Genotype and allele frequencies of drug-metabolizing enzymes and drug transporter genes affecting immunosuppressants in the Spanish white population.

    PubMed

    Bosó, Virginia; Herrero, María J; Buso, Enrique; Galán, Juan; Almenar, Luis; Sánchez-Lázaro, Ignacio; Sánchez-Plumed, Jaime; Bea, Sergio; Prieto, Martín; García, María; Pastor, Amparo; Sole, Amparo; Poveda, José Luis; Aliño, Salvador F

    2014-04-01

    Interpatient variability in drug response can be widely explained by genetically determined differences in metabolizing enzymes, drug transporters, and drug targets, leading to different pharmacokinetic and/or pharmacodynamic behaviors of drugs. Genetic variations affect or do not affect drug responses depending on their influence on protein activity and the relevance of such proteins in the pathway of the drug. Also, the frequency of such genetic variations differs among populations, so the clinical relevance of a specific variation is not the same in all of them. In this study, a panel of 33 single nucleotide polymorphisms in 14 different genes (ABCB1, ABCC2, ABCG2, CYP2B6, CYP2C19, CYP2C9, CYP3A4, CYP3A5, MTHFR, NOD2/CARD15, SLCO1A2, SLCO1B1, TPMT, and UGT1A9), encoding for the most relevant metabolizing enzymes and drug transporters relating to immunosuppressant agents, was analyzed to determine the genotype profile and allele frequencies in comparison with HapMap data. A total of 570 Spanish white recipients and donors of solid organ transplants were included. In 24 single nucleotide polymorphisms, statistically significant differences in allele frequency were observed. The largest differences (>100%) occurred in ABCB1 rs2229109, ABCG2 rs2231137, CYP3A5 rs776746, NOD2/CARD15 rs2066844, TPMT rs1800462, and UGT1A9 rs72551330. In conclusion, differences were recorded between the Spanish and other white populations in terms of allele frequency and genotypic distribution. Such differences may have implications in relation to dose requirements and drug-induced toxicity. These data are important for further research to help explain interindividual pharmacokinetic and pharmacodynamic variability in response to drug therapy.

  2. Circulating lysosomal enzymes and acute hepatic necrosis.

    PubMed Central

    Gove, C D; Wardle, E N; Williams, R

    1981-01-01

    The activities of the lysosomal enzymes acid and neutral protease, N-acetylglucosaminidase, and acid phosphatase were measured in the serum of patients with fulminant hepatic failure. Acid protease (cathepsin D) activity was increased about tenfold in patients who died and nearly fourfold in those who survived fulminant hepatic failure after paracetamol overdose, whereas activities were increased equally in patients with fulminant hepatic failure due to viral hepatitis whether or not they survived. A correlation was found between serum acid protease activity and prothrombin time, and the increase in cathepsin D activity was sustained over several days compared with aspartate aminotransferase, which showed a sharp early peak and then a fall. Circulating lysosomal proteases can damage other organs, and measurement of their activity may therefore be of added value in assessing prognosis in this condition. PMID:7007443

  3. Clinically relevant genetic variants of drug-metabolizing enzyme and transporter genes detected in Thai children and adolescents with autism spectrum disorder

    PubMed Central

    Medhasi, Sadeep; Pasomsub, Ekawat; Vanwong, Natchaya; Ngamsamut, Nattawat; Puangpetch, Apichaya; Chamnanphon, Montri; Hongkaew, Yaowaluck; Limsila, Penkhae; Pinthong, Darawan; Sukasem, Chonlaphat

    2016-01-01

    Single-nucleotide polymorphisms (SNPs) among drug-metabolizing enzymes and transporters (DMETs) influence the pharmacokinetic profile of drugs and exhibit intra- and interethnic variations in drug response in terms of efficacy and safety profile. The main objective of this study was to assess the frequency of allelic variants of drug absorption, distribution, metabolism, and elimination-related genes in Thai children and adolescents with autism spectrum disorder. Blood samples were drawn from 119 patients, and DNA was extracted. Genotyping was performed using the DMET Plus microarray platform. The allele frequencies of the DMET markers were generated using the DMET Console software. Thereafter, the genetic variations of significant DMET genes were assessed. The frequencies of SNPs across the genes coding for DMETs were determined. After filtering the SNPs, 489 of the 1,931 SNPs passed quality control. Many clinically relevant SNPs, including CYP2C19*2, CYP2D6*10, CYP3A5*3, and SLCO1B1*5, were found to have frequencies similar to those in the Chinese population. These data are important for further research to investigate the interpatient variability in pharmacokinetics and pharmacodynamics of drugs in clinical practice. PMID:27110117

  4. Genetic polymorphisms of the drug-metabolizing enzyme CYP2C19 in the Uyghur population in northwest China.

    PubMed

    Jin, Tianbo; Zhang, Mingxia; Yang, Hua; Geng, Tingting; Zhang, Ning; Feng, Tian; Ma, Yajuan; Yuan, Dongya; Kang, Longli

    2015-11-02

    1. CYP2C19 is a clinically important enzyme and is involved in the metabolism of approximately 10% of drugs used in daily clinical practice. Previous studies mainly focused on Chinese Han populations or other ethnic groups, little is known about Uyghur populations. 2. The present study was designed to determine the genetic basis of CYP2C19 polymorphisms. 3. We used direct sequencing to investigate the promoter, exons and surrounding introns, and 3'-untranslated region of the CYP2C19 gene in 96 unrelated healthy Uyghur individuals. 4. A total of 31 different CYP2C19 polymorphisms were identified in the Uyghur population, three of which were novel, including two nonsynonymous variants (57807A > M, Gln279Pro and 19257G > R, Asp262Asn) and one synonymous variants in exon 5 (19184T > Y, Leu237Leu). In addition, CYP2C19*1, *2 and *3 alleles showed frequencies of 83.34%, 14.06% and 2.08%, respectively. 5. This is the first study that systematically screened the polymorphisms of the whole CYP2C19 gene in Uyghur population. Hence, our results provided important information on CYP2C19 polymorphisms in Uyghur population and could be helpful for future personalized medicine studies in Uyghur population generally.

  5. Phosphorylation of cytochromes P450: First discovery of a posttranslational modification of a drug-metabolizing enzyme

    SciTech Connect

    Oesch-Bartlomowicz, B. . E-mail: oeschb@uni-mainz.de; Oesch, F.

    2005-12-09

    Cytochromes P450 (CYP) are important components of xenobiotic-metabolizing monooxygenases (CYP-dependent monooxygenases). Their regulation by induction, most commonly by transcriptional activation, mediated by xenobiotics, normally substrates of the corresponding CYP, is well known and has been widely studied. Our team has discovered an additional important regulation of xenobiotic-metabolizing CYPs pertaining to posttranslational modification by phosphorylation. Individual CYPs are phosphorylated by different protein kinases, leading to CYP isoenzyme-selective changes in the metabolism of individual substrates and consequent drastic changes in the control of genotoxic metabolites. Best studied are the CYP phosphorylations by the cAMP-dependent protein kinase A. Most recently, we discovered that cAMP not only leads to drastic changes in the activity of individual CYPs, but also to drastic changes in the nuclear localization of the CYP-related transcription factor Ah receptor (AHR). The consequences are very different from those of AHR nuclear translocation mediated by the classical ligands (enzyme inducers such as dioxin) and are likely to represent the long-sought physiological function of the AHR, its persistent disturbance by long-lived ligands such as dioxin may well be the reason for its high toxicity.

  6. Effect of diet on the development of drug metabolism by cytochrome P-450 enzymes in healthy infants.

    PubMed

    Blake, Michael J; Abdel-Rahman, Susan M; Pearce, Robin E; Leeder, J Steven; Kearns, Gregory L

    2006-12-01

    Orally administered caffeine and dextromethorphan (DM) were used as pharmacologic probes to determine the effect of infant diet on acquisition of cytochrome P-450 (CYP) enzyme activity during the first 6 mo of life. The caffeine elimination rate constant (ke) was determined from serum, and concentrations of caffeine, DM, and their respective metabolites were measured in urine by high-performance liquid chromatography (HPLC). Caffeine ke was low at 2 wk and displayed a significant positive linear correlation with age (p < 0.001); increasing faster in formula-fed than in breast-fed infants (p < 0.001). This occurred concomitantly with a significant increase in urinary 1,7-dimethylxanthine (17X) and 1-methylxanthine (1X) (p < 0.001), suggesting faster acquisition of CYP1A2 activity in formula-fed infants. The urinary molar ratio of (17X + 1X)/caffeine and age strongly predicted caffeine ke (r2 = 0.65; p < 0.001) irrespective of feeding type. CYP3A4 activity, assessed as the molar ratio of 3-hydroxymorphinan/dextrorphan showed a similar marked increase with postnatal age (p < 0.001) that was also greater in formula-fed than in breast-fed infants. Formula feeding appears to accelerate maturation of caffeine and DM metabolism by increasing the activity of CYP1A2 and CYP3A4, respectively. Dietary modification of CYP activity may modulate drug biotransformation and thus alter systemic exposure to xenobiotics from a very early age.

  7. Chemoprotective potentials of homoisoflavonoids and chalcones of Dracaena cinnabari: modulations of drug-metabolizing enzymes and antioxidant activity.

    PubMed

    Machala, M; Kubínová, R; Horavová, P; Suchý, V

    2001-03-01

    A series of homoisoflavonoids and chalcones, isolated from the endemic tropical plant Dracaena cinnabari Balf. (Agavaceae), were tested for their potential to inhibit cytochrome P4501A (CYP1A) enzymes and Fe-enhanced in vitro peroxidation of microsomal lipids in C57B1/6 mouse liver. The effects of the polyphenolic compounds were compared with those of prototypal flavonoid modulators of CYP1A and the well-known antioxidant, butylated hydroxytoluene. 2-Hydroxychalcone and partly 4,6-dihydroxychalcone were found to be strong inhibitors of CYP1A-dependent 7-ethoxyresorufin O-deethylase (EROD) activity in vitro comparable to the effects of quercetin and chrysin. The first screening of flavonoids and chalcones of Dracaena cinnabari for antioxidant activity was done in an in vitro microsomal peroxidation assay. While chalcones were shown to be poor antioxidants, 7,8-methylenedioxy-3(4-hydroxybenzyl) chromane, as one of the tested homoisoflavonoids, exhibited a strong antioxidant activity comparable to that of the strongest flavonol antioxidant, quercetin.

  8. Effects of hexaammine cobalt (III) chloride on oxidative stress-related parameters and drug metabolizing enzymes in mice.

    PubMed

    Singh, Amarjit; Kalla, Natwar R; Sharma, Raj P; Sharma, Rajeshwar

    2007-01-01

    Hexaammine cobalt (III) chloride has been advocated as a potential anticarcinogenic compound. There is no information on the effects of this compound on oxidative stress-related parameters in animals. In the present study the effects of administration of hexaammine cobalt (III) chloride in drinking water to balb/c male mice at doses of 25, 50, and 100 ppm for 14 weeks were examined. The tissue distribution of the compound was seen in liver, kidney, lung, intestine, blood, and spleen. The effects of the compound were monitored on levels of lipid peroxidation, GSH content, and activities of SOD, catalase, GST, and Cyt P450, along with the liver and kidney function tests. The results show that the cobalt accumulated maximally in kidney followed by liver, intestine, blood, spleen, and lung in decreasing order, in a dose-dependent manner. GSH and GST also showed increase in a dose-dependent manner while SOD and catalase showed increase with the highest dose only. Liver and kidney function tests showed no untoward change with any dose at the end of the study. The results suggest an antioxidant potentiating effect of the hexaammine cobalt (III) chloride besides nontoxicity to liver and kidney. Since the ability to induce an increase of GSH and GST along with other detoxifying enzymes by anticarcinogenic agents has been reported to correlate with the inhibition of tumorigenesis, the cobalt complex might qualify as a potential cancer chemopreventive agent.

  9. Establishing population distribution of drug-metabolizing enzyme activities for the use of salivary caffeine as a dynamic liver function marker in a Singaporean Chinese population.

    PubMed

    Chia, Hazel Yiting; Yau, Wai-Ping; Ho, Han Kiat

    2016-04-01

    The salivary paraxanthine/caffeine molar ratio has been proposed as a novel dynamic liver function test to guide dose adjustments of drugs hepatically cleared by CYP1A2. Its usability requires an established population norm as well as the factors influencing the ratio and actual concentrations. To address this knowledge gap, salivary caffeine and paraxanthine concentrations were measured at 4 h post caffeine dose in healthy Chinese individuals who had undergone 24 h of caffeine abstinence. The metabolic ratio was calculated and statistical analysis was performed. From the 52 participants (26 males; 30 regular caffeine consumers) recruited, the salivary paraxanthine/caffeine molar ratio was normally distributed with a mean and SD of 0.5 ± 0.2. No statistically significant factors (BMI, body weight, gender and regularity of caffeine intake) affecting the metabolic ratio were found. The caffeine concentration and total caffeine plus paraxanthine concentrations were lower in males than in females, and lower in regular caffeine consumers than in non-regular caffeine consumers. The 4 h salivary metabolic ratio (mean: 0.5) was generally not significantly different from the literature reported salivary, serum and plasma ratios measured at 4-9 h in healthy individuals (mean range 0.4-0.7) but was significantly higher than the literature reported 6 h plasma ratio and salivary ratios measured at 1-6 h in patients with liver disease or mild abnormal liver function tests (mean range 0.03-0.2). Overall, the population norm of the salivary metabolic ratio in a Singaporean Chinese population established in this study is distinct from individuals with liver disease or mild abnormal liver function tests and provides the benchmark for dosage adjustments of drugs metabolized by CYP1A2. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Pharmacokinetics and Pharmacodynamics of Phase II Drug Metabolizing/Antioxidant Enzymes Gene Response by Anti-cancer Agent Sulforaphane in Rat Lymphocytes

    PubMed Central

    Wang, Hu; Khor, Tin Oo; Yang, Qian; Huang, Ying; Wu, Tien-yuan; Saw, Constance Lay-Lay; Lin, Wen; Androulakis, Ioannis P.; Kong, Ah-Ng Tony

    2012-01-01

    PURPOSE This study assesses the pharmacokinetics (PK) and pharmacodynamics (PD) of Nrf2-mediated increased expression of Phase II drug metabolizing enzyme (DME) and antioxidant enzymes which represents an important component of cancer chemoprevention in rat lymphocytes following intravenous (i.v.) administration of an anti-cancer phytochemical sulforaphane (SFN) METHODS SFN was administered intravenously to four groups of male Sprague-Dawley JVC rats each group comprising four animals. Blood samples were drawn at selected time points. Plasma were obtained from half of the blood samples and analyzed using a validated LC-MS/MS method. Lymphocytes were collected from the remaining blood samples using Ficoll-Paque™ Plus centrifuge medium. Lymphocyte RNAs were extracted, converted to cDNA, and quantitative real-time PCR analyses were performed and fold changes were calculated against those at time zero for the relative expression of Nrf2-target genes of phase II DME/antioxidant enzymes. PK-PD modeling was conducted based on Jusko’s indirect response model (IDR) using GastroPlus™ and Bootstrap Method. RESULTS SFN plasma concentration declined biexponentially and the pharmacokinetic parameters were generated. Rat lymphocyte mRNA expression levels showed no change for GSTM1, SOD, NF-κB, UGT1A1, or UGT1A6. Moderate increases (2-5 folds) over the time zero were seen for HO-1, Nrf2, and NQO1, and significant increase (> 5 folds) for GSTT1, GPx1, and Maf. PK-PD analyses using GastroPlus™ and Bootstrap method provided reasonable fitting for the PK and PD profiles and parameter estimates. CONCLUSION Our present study shows that SFN could induce Nrf2-mediated phase II DME/antioxidant mRNA expression for NQO1, GSTT1, Nrf2, GPx, Maf, and HO-1 in rat lymphocytes after i.v. administration, suggesting that Nrf2-mediated mRNA expression in lymphocytes may serve as surrogate biomarkers. The PK-PD IDR model simultaneously linking the plasma concentrations of SFN and the PD

  11. Grapefruit and oroblanco enhance hepatic detoxification enzymes in rats: possible role in protection against chemical carcinogenesis.

    PubMed

    Hahn-Obercyger, Michal; Stark, Aliza H; Madar, Zecharia

    2005-03-09

    Citrus fruits are considered to be functional foods that promote good health. This study was carried out to assess the effect of oroblanco and grapefruit consumption on hepatic detoxification enzymes. Male Sprague-Dawley rats were provided with either regular drinking water (control) or experimental treatments of oroblanco juice, grapefruit juice, or a sugar mix for 6 weeks. After 1 week of treatment, half the animals in each group were injected with the procarcinogen 1,2-dimethylhydrazine. Grapefruit juice significantly increased activity and expression of the hepatic phase I enzyme, cytochrome P450 CYP1A1, with a marked trend toward enhanced NAD(P)H:quinone reductase (QR) activity. Oroblanco juice significantly increased glutathione S-transferase phase II enzyme activity along with CYP1A1 expression and a notable trend toward increased activity of both CYP1A1 and QR. These results suggest that these citrus fruits are bifunctional inducers, modulating both phase I and phase II drug-metabolizing enzymes to enhance hepatic detoxification.

  12. Differentiation of monkey embryonic stem cells to hepatocytes by feeder-free dispersion culture and expression analyses of cytochrome p450 enzymes responsible for drug metabolism.

    PubMed

    Maruyama, Junya; Matsunaga, Tamihide; Yamaori, Satoshi; Sakamoto, Sakae; Kamada, Noboru; Nakamura, Katsunori; Kikuchi, Shinji; Ohmori, Shigeru

    2013-01-01

    We reported previously that monkey embryonic stem cells (ESCs) were differentiated into hepatocytes by formation of embryoid bodies (EBs). However, this EB formation method is not always efficient for assays using a large number of samples simultaneously. A dispersion culture system, one of the differentiation methods without EB formation, is able to more efficiently provide a large number of feeder-free undifferentiated cells. A previous study demonstrated the effectiveness of the Rho-associated kinase inhibitor Y-27632 for feeder-free dispersion culture and induction of differentiation of monkey ESCs into neural cells. In the present study, the induction of differentiation of cynomolgus monkey ESCs (cmESCs) into hepatocytes was performed by the dispersion culture method, and the expression and drug inducibility of cytochrome P450 (CYP) enzymes in these hepatocytes were examined. The cmESCs were successfully differentiated into hepatocytes under feeder-free dispersion culture conditions supplemented with Y-27632. The hepatocytes differentiated from cmESCs expressed the mRNAs for three hepatocyte marker genes (α-fetoprotein, albumin, CYP7A1) and several CYP enzymes, as measured by real-time polymerase chain reaction. In particular, the basal expression of cmCYP3A4 (3A8) in these hepatocytes was detected at mRNA and enzyme activity (testosterone 6β-hydroxylation) levels. Furthermore, the expression and activity of cmCYP3A4 (3A8) were significantly upregulated by rifampicin. These results indicated the effectiveness of Y-27632 supplementation for feeder-free dispersed culture and induction of differentiation into hepatocytes, and the expression of functional CYP enzyme(s) in cmESC-derived hepatic cells.

  13. Automated method for study of drug metabolism

    NASA Technical Reports Server (NTRS)

    Furner, R. L.; Feller, D. D.

    1973-01-01

    Commercially available equipment can be modified to provide automated system for assaying drug metabolism by continuous flow-through. System includes steps and devices for mixing drug with enzyme and cofactor in the presence of pure oxygen, dialyzing resulting metabolite against buffer, and determining amount of metabolite by colorimetric method.

  14. A QUANTITATIVE MODEL FOR XENOBIOTIC METABOLIZING ENZYME (XME) INDUCTION REGULATED BY THE PREGNANE X RECEPTOR (PXR)

    EPA Science Inventory

    The nuclear receptor, PXR, is an integral part of the regulation of hepatic metabolism. It has been shown to regulate specific CYPs (phase I drug-metabolizing enzymes) as well as certain phase II drug metabolism activities, including UDP-glucuronosyl transferase (UGT), sulfotran...

  15. Effect of tetrahydrocurcumin on the profiles of drug-metabolizing enzymes induced by a high fat and high fructose diet in mice.

    PubMed

    Jearapong, Nattharat; Chatuphonprasert, Waranya; Jarukamjorn, Kanokwan

    2015-09-05

    Cytochrome P450 (CYP), a superfamily of hepatic monooxygenase enzymes, catalyzes biotransformation of endogenous compounds and xenobiotics. Modification of CYPs associated with metabolic diseases and continuous consumption of diet with excessive energy levels. Tetrahydrocurcumin (THC) exhibited beneficial effects in metabolic syndromes such as diabetic mellitus and dyslipidemia. The present study aimed to investigate the effects of THC and vitamin E (vitE) on the expression profiles of CYPs in the livers of mice fed with the high fat and high fructose diet. In addition to ad libitum access to commercial regular diet, the high fat and high fructose diet (HFD) group of adult male ICR mice was administered a HFD, which consisted of intragastric administration of hydrogenated soybean oil (1mL/day) and the addition of 20% fructose to the drinking water for 8weeks. During the induction period, subgroups of mice (n=5) were daily intragastrically administered with THC (100 or 200mg/kg/day) or vitE (100mg/kg/day). The expressions of CYP mRNA and protein were quantified using real-time PCR and the levels of these proteins were quantified using immunoblotting. Continuous consuming of high fat and high fructose for 8weeks significantly increased the expressions of Cyp1a1, Cyp1a2, Cyp1b1, Cyp2c29, and Cyp3a11 while THC ultimately normalized these CYPs profiles. In the control mice, most of the investigated CYPs was unchanged by THC, with the exception that the Cyp1a1, Cyp2b9, and Cyp3a11 proteins were elevated. These findings provided additional important information on the effects of THC on diet induced-metabolic dysfunctions. However, drug interactions due to the use of THC as an alternative supplement are of concern, particularly in the combinations that include a drug that is a substrate of Cyp1a1, Cyp2b9, and Cyp3a11.

  16. Effects of surfactants on the contents of metallothionein, heme and hemoproteins and on the activities of heme oxygenase and drug-metabolizing enzymes in rats pretreated with phenobarbital or. beta. -naphthoflavone

    SciTech Connect

    Ariyoshi, Toshihiko; Hasegawa, Hiroyuki; Matsumoto, Hideki; Arizono, Koji )

    1991-01-01

    Synthetic surfactants as major constituent of detergent products are widely used in consumer and industrial fields, and hence environmental and toxicological investigations of surfactants are numerous. In the previous study, the authors observed that intraperitoneal administration of surfactants such as sodium dodecyl sulfate (SDS), sodium n-dodecylbenzenesulfonate (LAS) and polyoxyethyleneglycol nonylphenyl ether (Emulgen 913) to rats depressed the content of microsomal cytochrome P-450, while they enhanced markedly the activity of heme oxygenase, the first and rate-limiting enzyme in heme degradation. In addition, they noted an increase of metallothionein content in the liver of rats treated with LAS. In this study, the authors investigated the effects of surfactants on metallothionein, heme, hemoproteins, heme oxygenase and drug-metabolizing enzymes in the liver of rats pretreated with phenobarbital or {beta}-naphthoflavone.

  17. Short-term fasting alters cytochrome P450-mediated drug metabolism in humans.

    PubMed

    Lammers, Laureen A; Achterbergh, Roos; de Vries, Emmely M; van Nierop, F Samuel; Klümpen, Heinz-Josef; Soeters, Maarten R; Boelen, Anita; Romijn, Johannes A; Mathôt, Ron A A

    2015-06-01

    Experimental studies indicate that short-term fasting alters drug metabolism. However, the effects of short-term fasting on drug metabolism in humans need further investigation. Therefore, the aim of this study was to evaluate the effects of short-term fasting (36 h) on P450-mediated drug metabolism. In a randomized crossover study design, nine healthy subjects ingested a cocktail consisting of five P450-specific probe drugs [caffeine (CYP1A2), S-warfarin (CYP2C9), omeprazole (CYP2C19), metoprolol (CYP2D6), and midazolam (CYP3A4)] on two occasions (control study after an overnight fast and after 36 h of fasting). Blood samples were drawn for pharmacokinetic analysis using nonlinear mixed effects modeling. In addition, we studied in Wistar rats the effects of short-term fasting on hepatic mRNA expression of P450 isoforms corresponding with the five studied P450 enzymes in humans. In the healthy subjects, short-term fasting increased oral caffeine clearance by 20% (P = 0.03) and decreased oral S-warfarin clearance by 25% (P < 0.001). In rats, short-term fasting increased mRNA expression of the orthologs of human CYP1A2, CYP2C19, CYP2D6, and CYP3A4 (P < 0.05), and decreased the mRNA expression of the ortholog of CYP2C9 (P < 0.001) compared with the postabsorptive state. These results demonstrate that short-term fasting alters cytochrome P450-mediated drug metabolism in a nonuniform pattern. Therefore, short-term fasting is another factor affecting cytochrome P450-mediated drug metabolism in humans.

  18. Drug metabolism for the perplexed medicinal chemist.

    PubMed

    Testa, Bernard

    2009-11-01

    Two related and significant issues may elicit perplexity in medicinal chemists and are discussed here. First, a broad presentation of the pharmacological and toxicological consequences of drug metabolism should justify the significance of drug metabolism and serve as an incentive to further study. When comparing the pharmacological activities of a drug and its metabolite(s), a continuum is found which ranges from soft drugs (no active metabolites) to prodrugs (inactive per se, as illustrated here with clopidogrel and prasugrel). Innumerable intermediate cases document drugs whose activity is shared by one or more metabolites, as exemplified with tamoxifen. The toxicological consequences of metabolism at the molecular, macromolecular, and macroscopic levels are manyfold. A brief overview is offered together with a summary of the reactions of toxification and detoxification of the antiepileptic valproic acid. The second issue discussed in the review is a comparison of the relative significance of cytochromes P450 and other oxidoreductases (EC 1), hydrolases (EC 3), and transferases (EC 2) in drug metabolism, based on a 'guesstimate' of the number of drug metabolites that are known to be produced by them. The conclusion is that oxidoreductases are the main enzymes responsible for the formation of toxic or active metabolites, whereas transferases play the major role in producing inactive and nontoxic metabolites.

  19. Graphic rule for drug metabolism systems.

    PubMed

    Chou, Kuo-Chen

    2010-05-01

    Using graphic rules to deal with kinetic systems is an elegant approach by combining the graph representation (schematic representation) and rigorous mathematical derivation. It bears the following advantages: (1) providing an intuitive picture or illuminative insights; (2) helping grasp the key points from complicated details; (3) greatly simplifying many tedious, laborious, and error-prone calculations; and (4) able to double-check the final results. In this mini review, the non-steady state graphic rule in enzyme-catalyzed kinetics and protein-folding kinetics was extended to cover drug-metabolic systems. As a demonstration, a step-by-step illustration is presented showing how to use the graphic rule to derive the concentrations of the parent drug and its metabolites vs. time for the seliciclib, vildagliptin, and cyclin-dependent kinase inhibitor (AG-024322) metabolic systems, respectively. It can be seen from these paradigms that the graphic rule is particularly useful to analyze complicated drug metabolic systems and ensure the correctness of the derived results. Meanwhile, the intuitive feature of graphic representation may facilitate analyzing and classifying drug metabolic systems; e.g., according to their directed graphs, the metabolism of seliciclib and the metabolism of vildagliptin can be categorized as 0-->5 mechanism while that of AG-024322 as 0-->4-->3 mechanism.

  20. Drug metabolizing capacity in vitro and in vivo--II. Correlations between hepatic microsomal monooxygenase markers in phenobarbital-induced rats.

    PubMed

    Matthew, D E; Houston, J B

    1990-08-15

    Pretreatment with various doses of phenobarbital (PB) has been used to create a pool of rats with a wide range of hepatic microsomal monooxygenase activity to systematically examine relationships between and within in vivo and in vitro markers. The in vivo clearance of tolbutamide (TOL), theophylline (TH), antipyrine (AP) and its metabolites were determined in the same rats used for hepatic microsome preparation and assessment of P450 content and activities (via 7-ethoxycoumarin O-deethylase (ECOD), 7 ethoxyresorufin O-deethylase, 7-methoxycoumarin O-demethylase (MCOD) and aldrin epoxidase determinations). A graded dose-response relationship was found between PB treatment and most but not all parameters. The need for careful selection of in vivo and as well as in vitro markers is apparent from these studies. The most responsive parameters--TOL and AP clearances, MCOD and ECOD activities--were also those producing the strongest in vivo-in vitro correlations. Despite the diffuse nature of the PB induced response in P450 complement, good predictive relationships were apparent between ECOD and TOL clearance (r2 = 0.88).

  1. [Quantification of the drug-metabolizing enzyme system in liver diseases: a comparison between antipyrine saliva clearance and the aminopyrine breath test].

    PubMed

    von Mandach, U; Jost, G; Preisig, R

    1985-05-11

    The metabolic activity of the hepatic cytochrome P450 system was studied in 53 ambulatory subjects. 18 of these were cirrhotics and 23 had non-cirrhotic liver disease, documented by biopsy, serologic, ultrasound or computerized tomography findings, and characterized by quantitative liver function tests, such as galactose elimination capacity and indocyanine green fractional clearance. For comparison, 12 normal control subjects were also included. All subjects were given 10 mg/kg body weight antipyrine and saliva concentrations determined with an HPLC-method at 24 and 48 hours after dosing. Antipyrine saliva clearance (ASC) was calculated according to a two-point method (Cl1), and compared with a one-point method (Cl2) using the 24 h sample only. These subjects also underwent an aminopyrine breath test (ABT), breath samples being collected at regular intervals during 60 minutes following injection of a tracer dose of 1.5 muCi (14C-dimethylamino)antipyrine. Cl1 and Cl2 correlated strongly (r = 0.93). On the basis of smaller variations (particularly in control subjects), better definition of disease severity and convenience and time saving, Cl2 is to be preferred. Comparison of Cl2 with ABT showed that both procedures apparently quantify overlapping enzymatic activities. However, the relationship between Cl2 and ABT values, albeit highly significant (r = 0.72), suggests that only about half of the variables are subject to the same determinant. In addition, a positive intercept of the regression line extrapolated to the Cl2 axis points to quantitatively important extrahepatic breakdown of antipyrine. The results suggest that, in view of the wide variation in normal values (presumably in part influenced by exogenous pollutants), ASC only provides an approximation of hepatic metabolic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Short-term calorie restriction feminizes the mRNA profiles of drug metabolizing enzymes and transporters in livers of mice.

    PubMed

    Fu, Zidong Donna; Klaassen, Curtis D

    2014-01-01

    Calorie restriction (CR) is one of the most effective anti-aging interventions in mammals. A modern theory suggests that aging results from a decline in detoxification capabilities and thus accumulation of damaged macromolecules. The present study aimed to determine how short-term CR alters mRNA profiles of genes that encode metabolism and detoxification machinery in the liver. Male C57BL/6 mice were fed CR (0, 15, 30, or 40%) diets for one month, followed by mRNA quantification of 98 xenobiotic processing genes (XPGs) in the liver, including 7 uptake transporters, 39 phase-I enzymes, 37 phase-II enzymes, 10 efflux transporters, and 5 transcription factors. In general, 15% CR did not alter mRNAs of most XPGs, whereas 30 and 40% CR altered over half of the XPGs (32 increased and 29 decreased). CR up-regulated some phase-I enzymes (fold increase), such as Cyp4a14 (12), Por (2.3), Nqo1 (1.4), Fmo2 (5.4), and Fmo3 (346), and numerous number of phase-II enzymes, such as Sult1a1 (1.2), Sult1d1 (2.0), Sult1e1 (33), Sult3a1 (2.2), Gsta4 (1.3), Gstm2 (1.3), Gstm3 (1.7), and Mgst3 (2.2). CR feminized the mRNA profiles of 32 XPGs in livers of male mice. For instance, CR decreased the male-predominantly expressed Oatp1a1 (97%) and increased the female-predominantly expressed Oatp1a4 (11). In conclusion, short-term CR alters the mRNA levels of over half of the 98 XPGs quantified in livers of male mice, and over half of these alterations appear to be due to feminization of the liver.

  3. Significant inhibitory impact of dibenzyl trisulfide and extracts of Petiveria alliacea on the activities of major drug-metabolizing enzymes in vitro: An assessment of the potential for medicinal plant-drug interactions.

    PubMed

    Murray, J; Picking, D; Lamm, A; McKenzie, J; Hartley, S; Watson, C; Williams, L; Lowe, H; Delgoda, R

    2016-06-01

    Dibenzyl trisulfide (DTS) is the major active ingredient expressed in Petiveria alliacea L., a shrub widely used for a range of conditions, such as, arthritis, asthma and cancer. Given its use alone and concomitantly with prescription medicines, we undertook to investigate its impact on the activities of important drug metabolizing enzymes, the cytochromes P450 (CYP), a key family of enzymes involved in many adverse drug reactions. DTS and seven standardized extracts from the plant were assessed for their impact on the activities of CYPs 1A2, 2C19, 2C9, 2D6 and 3A4 on a fluorometric assay. DTS revealed significant impact against the activities of CYPs 1A2, 2C19 and 3A4 with IC50 values of 1.9, 4.0 and 3.2μM, respectively, which are equivalent to known standard inhibitors of these enzymes (furafylline, and tranylcypromine), and the most potent interaction with CYP1A2 displayed irreversible enzyme kinetics. The root extract, drawn with 96% ethanol (containing 2.4% DTS), displayed IC50 values of 5.6, 3.9 and 4.2μg/mL respectively, against the same isoforms, CYPs 1A2, 2C19 and 3A4. These investigations identify DTS as a valuable CYP inhibitor and P. alliacea as a candidate plant worthy of clinical trials to confirm the conclusions that extracts yielding high DTS may lead to clinically relevant drug interactions, whilst extracts yielding low levels of DTS, such as aqueous extracts, are unlikely to cause adverse herb-drug interactions.

  4. Short-term calorie restriction feminizes the mRNA profiles of drug metabolizing enzymes and transporters in livers of mice

    SciTech Connect

    Fu, Zidong Donna; Klaassen, Curtis D.

    2014-01-01

    Calorie restriction (CR) is one of the most effective anti-aging interventions in mammals. A modern theory suggests that aging results from a decline in detoxification capabilities and thus accumulation of damaged macromolecules. The present study aimed to determine how short-term CR alters mRNA profiles of genes that encode metabolism and detoxification machinery in the liver. Male C57BL/6 mice were fed CR (0, 15, 30, or 40%) diets for one month, followed by mRNA quantification of 98 xenobiotic processing genes (XPGs) in the liver, including 7 uptake transporters, 39 phase-I enzymes, 37 phase-II enzymes, 10 efflux transporters, and 5 transcription factors. In general, 15% CR did not alter mRNAs of most XPGs, whereas 30 and 40% CR altered over half of the XPGs (32 increased and 29 decreased). CR up-regulated some phase-I enzymes (fold increase), such as Cyp4a14 (12), Por (2.3), Nqo1 (1.4), Fmo2 (5.4), and Fmo3 (346), and numerous number of phase-II enzymes, such as Sult1a1 (1.2), Sult1d1 (2.0), Sult1e1 (33), Sult3a1 (2.2), Gsta4 (1.3), Gstm2 (1.3), Gstm3 (1.7), and Mgst3 (2.2). CR feminized the mRNA profiles of 32 XPGs in livers of male mice. For instance, CR decreased the male-predominantly expressed Oatp1a1 (97%) and increased the female-predominantly expressed Oatp1a4 (11). In conclusion, short-term CR alters the mRNA levels of over half of the 98 XPGs quantified in livers of male mice, and over half of these alterations appear to be due to feminization of the liver. - Highlights: • Utilized a graded CR model in male mice • The mRNA profiles of xenobiotic processing genes (XPGs) in liver were investigated. • CR up-regulates many phase-II enzymes. • CR tends to feminize the mRNA profiles of XPGs.

  5. Predicting tumor responses to mitomycin C on the basis of DT-diaphorase activity or drug metabolism by tumor homogenates: implications for enzyme-directed bioreductive drug development.

    PubMed

    Phillips, R M; Burger, A M; Loadman, P M; Jarrett, C M; Swaine, D J; Fiebig, H H

    2000-11-15

    Mitomycin C (MMC) is a clinically used anticancer drug that is reduced to cytotoxic metabolites by cellular reductases via a process known as bioreductive drug activation. The identification of key enzymes responsible for drug activation has been investigated extensively with the ultimate aim of tailoring drug administration to patients whose tumors possess the biochemical machinery required for drug activation. In the case of MMC, considerable interest has been centered upon the enzyme DT-diaphorase (DTD) although conflicting reports of good and poor correlations between enzyme activity and response in vitro and in vivo have been published. The principle aim of this study was to provide a definitive answer to the question of whether tumor response to MMC could be predicted on the basis of DTD activity in a large panel of human tumor xenografts. DTD levels were measured in 45 human tumor xenografts that had been characterized previously in terms of their sensitivity to MMC in vitro and in vivo (the in vivo response profile to MMC was taken from work published previously). A poor correlation between DTD activity and antitumor activity in vitro as well as in vivo was obtained. This study also assessed the predictive value of an alternative approach based upon the ability of tumor homogenates to metabolize MMC. This approach is based on the premise that the overall rate of MMC metabolism may provide a better indicator of response than single enzyme measurements. MMC metabolism was evaluated in tumor homogenates (clarified by centrifugation at 1000 x g for 1 min) by measuring the disappearance of the parent compound by HPLC. In responsive [T/C <10% (T/C defined as the relative size of treated and control tumors)] and resistant (T/C >50%) tumors, the mean half life of MMC was 75+/-48.3 and 280+/-129.6 min, respectively. The difference between the two groups was statistically significant (P < 0.005). In conclusion, these results unequivocally demonstrate that response to

  6. Drug metabolism and transport during pregnancy: how does drug disposition change during pregnancy and what are the mechanisms that cause such changes?

    PubMed

    Isoherranen, Nina; Thummel, Kenneth E

    2013-02-01

    There is increasing evidence that pregnancy alters the function of drug-metabolizing enzymes and drug transporters in a gestational-stage and tissue-specific manner. In vivo probe studies have shown that the activity of several hepatic cytochrome P450 enzymes, such as CYP2D6 and CYP3A4, is increased during pregnancy, whereas the activity of others, such as CYP1A2, is decreased. The activity of some renal transporters, including organic cation transporter and P-glycoprotein, also appears to be increased during pregnancy. Although much has been learned, significant gaps still exist in our understanding of the spectrum of drug metabolism and transport genes affected, gestational age-dependent changes in the activity of encoded drug metabolizing and transporting processes, and the mechanisms of pregnancy-induced alterations. In this issue of Drug Metabolism and Disposition, a series of articles is presented that address the predictability, mechanisms, and magnitude of changes in drug metabolism and transport processes during pregnancy. The articles highlight state-of-the-art approaches to studying mechanisms of changes in drug disposition during pregnancy, and illustrate the use and integration of data from in vitro models, animal studies, and human clinical studies. The findings presented show the complex inter-relationships between multiple regulators of drug metabolism and transport genes, such as estrogens, progesterone, and growth hormone, and their effects on enzyme and transporter expression in different tissues. The studies provide the impetus for a mechanism- and evidence-based approach to optimally managing drug therapies during pregnancy and improving treatment outcomes.

  7. Novel drug metabolism indices for pharmacogenetic functional status based on combinatory genotyping of CYP2C9, CYP2C19 and CYP2D6 genes

    PubMed Central

    Villagra, David; Goethe, John; Schwartz, Harold I; Szarek, Bonnie; Kocherla, Mohan; Gorowski, Krystyna; Windemuth, Andreas; Ruaño, Gualberto

    2011-01-01

    Aims We aim to demonstrate clinical relevance and utility of four novel drug-metabolism indices derived from a combinatory (multigene) approach to CYP2C9, CYP2C19 and CYP2D6 allele scoring. Each index considers all three genes as complementary components of a liver enzyme drug metabolism system and uniquely benchmarks innate hepatic drug metabolism reserve or alteration through CYP450 combinatory genotype scores. Methods A total of 1199 psychiatric referrals were genotyped for polymorphisms in the CYP2C9, CYP2C19 and CYP2D6 gene loci and were scored on each of the four indices. The data were used to create distributions and rankings of innate drug metabolism capacity to which individuals can be compared. Drug-specific indices are a combination of the drug metabolism indices with substrate-specific coefficients. Results The combinatory drug metabolism indices proved useful in positioning individuals relative to a population with regard to innate drug metabolism capacity prior to pharmacotherapy. Drug-specific indices generate pharmacogenetic guidance of immediate clinical relevance, and can be further modified to incorporate covariates in particular clinical cases. Conclusions We believe that this combinatory approach represents an improvement over the current gene-by-gene reporting by providing greater scope while still allowing for the resolution of a single-gene index when needed. This method will result in novel clinical and research applications, facilitating the translation from pharmacogenomics to personalized medicine, particularly in psychiatry where many drugs are metabolized or activated by multiple CYP450 isoenzymes. PMID:21861665

  8. Pharmacogenomic Study Reveals New Variants of Drug Metabolizing Enzyme and Transporter Genes Associated with Steady-State Plasma Concentrations of Risperidone and 9-Hydroxyrisperidone in Thai Autism Spectrum Disorder Patients

    PubMed Central

    Medhasi, Sadeep; Pinthong, Darawan; Pasomsub, Ekawat; Vanwong, Natchaya; Ngamsamut, Nattawat; Puangpetch, Apichaya; Chamnanphon, Monpat; Hongkaew, Yaowaluck; Pratoomwun, Jirawat; Limsila, Penkhae; Sukasem, Chonlaphat

    2016-01-01

    The present study sought to investigate the genetic variants in drug metabolizing enzyme and transporter (DMET) genes associated with steady-state plasma concentrations of risperidone among Thai autism spectrum disorder (ASD) patients. ASD patients taking risperidone for at least 1 month were enrolled for this pharmacogenomic study. Genotyping profile was obtained using Affymetrix DMET Plus array interrogating 1931 variants in 231 genes. Steady-state plasma risperidone and 9-hydroxyrisperidone were measured using liquid chromatography/tandem mass spectrometry assay. The final analysis included 483 markers for 167 genes. Six variants, ABCB11 (c.3084A > G, c.∗420A > G, c.∗368G > A, and c.∗236G > A) and ADH7 (c.690G > A and c.-5360G > A), were found to be associated with plasma concentrations of risperidone. 9-Hydroxyrisperidone and the total active-moiety levels were associated with six gene variants, SCLO1B1 (c.-11187G > A and c.521T > C), SLCO1B3 (c.334G > T, c.699A > G, and c.1557G > A), and SLC7A5 c.∗438C > G. Polymorphisms in UGT2B4 c.∗448A > G and CYP2D6 (c.1661G > C, c.4180G > C, and c.-2178G > A) showed considerable but not significant associations with metabolic ratio. This pharmacogenomic study identifies new genetic variants of DMET genes in monitoring risperidone therapy. PMID:28018217

  9. Differences in metabolite burden of di(2-ethylhexyl)phthalate in pregnant and postpartum dams and their offspring in relation to drug-metabolizing enzymes in mice.

    PubMed

    Hayashi, Yumi; Ito, Yuki; Yanagiba, Yukie; Kamijima, Michihiro; Naito, Hisao; Nakajima, Tamie

    2012-04-01

    Di(2-ethylhexyl)phthalate (DEHP) induced adverse effects on mice offspring, and the metabolite mono(2-ethylhexyl)phthalate (MEHP) may be essential to determine the toxicity. In this experiment, we measured liver MEHP levels and the factors determining the metabolism, two enzyme activities [lipase and uridine 5'-diphosphate-glucuronosyltransferase (UGT)] or expression of cytochrome P450 4A14 (CYP4A14) in dams (on gestational day 18 and postnatal day 2) and their offspring. MEHP concentrations in the liver from pregnant dams were 1.5 times higher than those of postpartum dams at exposure to 0.05% DEHP. Accordingly, MEHP concentrations were 1.7 times higher in fetuses than in pups at the dose. Interestingly, lipase activity was 1.8-fold higher in pregnant dams than postpartum ones, but no such difference was noted in the activity between fetuses and pups. UGT activity was also 1.5-fold higher in pregnant dams than postpartum ones, whereas the activity in the fetuses was 1/2 that of pups. No difference was noted in CYP4A14 levels between pregnant and postpartum mice, whereas the levels in the fetuses were <1/10 those of pups. DEHP exposure did not influence lipase activity, whereas it slightly enhanced UGT activity and exclusively increased CYP4A14 levels in pregnant and/or postpartum dams. Taken together, the higher MEHP levels in pregnant dams than postpartum ones may be primarily due to higher lipase activities in pregnant dams, which may closely reflect those in fetuses and pups.

  10. Genetic polymorphism analysis of the drug-metabolizing enzyme CYP1A2 in a Uyghur Chinese population: a pilot study.

    PubMed

    Geng, Tingting; Zhang, Xi Yang; Wang, Li; Wang, Huijuan; Shi, Xugang; Kang, Longli; Hou, Peng; Jin, Tianbo

    2016-01-01

    1. CYP1A2 is a highly polymorphic gene and CYP1A2 enzyme results in broad inter-individual variability in response to certain pharmacotherapies, while little is known about the genetic variation of CYP1A2 in Uyghur Chinese population. The aim of the present study was to screen Uyghur volunteers for CYP1A2 genetic polymorphisms. 2. We used DNA sequencing to investigate promoter, exons, introns, and 3' UTR of the CYP1A2 gene in 96 unrelated healthy Uyghur individuals. We also used SIFT (Sorting Intolerant From Tolerant) and PolyPhen-2 (Polymorphism Phenotyping v2) to predict the protein function of the novel non-synonymous mutation in CYP1A2 coding regions. 3. We identified 20 different CYP1A2 polymorphisms in the Uyghur Chinese population, including two novel variants (119A > G and 2410G > A). Variant 119A > G was predicted to be probably damaging on protein function by PolyPhen-2, by contrast, 2410G > A was identified as benign. The allele frequencies of CYP1A2*1A, *1B, *1F, *1G, *1J, *1M, *4, and *9 were 23.4%, 53.1%, 3.7%, 2.6%, 2.6%, 13.5%, 0.5%, and 0.5%, respectively. The frequency of *1F, a putative high inducibility allele, was higher in our sample population compared with that in the Caucasian population (p < 0.05). The most common genotype combinations were *1A/*1B (46.9%) and *1B/*1M (27.1%). 4. Our results provide basic information on CYP1A2 polymorphisms in Uyghur individuals and suggest that the enzymatic activities of CYP1A2 may differ among the diverse ethnic populations of the world.

  11. Advances in drug metabolism and pharmacogenetics research in Australia.

    PubMed

    Mackenzie, Peter I; Somogyi, Andrew A; Miners, John O

    2017-02-01

    Metabolism facilitates the elimination, detoxification and excretion in urine or bile (as biotransformation products) of a myriad of structurally diverse drugs and other chemicals. The metabolism of drugs, non-drug xenobiotics and many endogenous compounds is catalyzed by families of drug metabolizing enzymes (DMEs). These include the hemoprotein-containing cytochromes P450, which function predominantly as monooxygenases, and conjugation enzymes that transfer a sugar, sulfate, acetate or glutathione moiety to substrates containing a suitable acceptor functional group. Drug and chemical metabolism, especially the enzymes that catalyse these reactions, has been the research focus of several groups in Australia for over four decades. In this review, we highlight the role of recent and current drug metabolism research in Australia, including elucidation of the structure and function of enzymes from the various DME families, factors that modulate enzyme activity in humans (e.g. drug-drug interactions, gene expression and genetic polymorphism) and the application of in vitro approaches for the prediction of drug metabolism parameters in humans, along with the broader pharmacological/clinical pharmacological and toxicological significance of drug metabolism and DMEs and their relevance to drug discovery and development, and to clinical practice.

  12. Hepatocytes as a tool in drug metabolism, transport and safety evaluations in drug discovery.

    PubMed

    Sahi, Jasminder; Grepper, Susan; Smith, Cornelia

    2010-09-01

    The liver is the primary site of metabolism for most drugs. Its major roles include detoxification of the systemic and portal blood, and production and secretion of critical blood and biliary components. A number of liver-derived in vitro systems, such as slices, primary and immortalized hepatocytes, microsomes and S9 fractions are used to assess the metabolism and potential toxicity of new chemical entities. Over the past decade, primary hepatocytes have become a standard in vitro tool to evaluate hepatic drug metabolism, cytochrome P450 (P450) induction, and drug interactions affecting hepatic metabolism. While earlier, hepatocytes were used in suspension for metabolic stability evaluations, more recent studies have demonstrated the added value of using these over longer terms in primary culture. Primary hepatocyte cultures are particularly useful in the evaluation of low turn-over compounds. Hepatic transporter studies are recommended for drug candidates that are predominantly eliminated through the bile. An appropriate strategy is to use primary hepatocytes to assess uptake, followed by singly transfected cell lines to identify the specific transporter(s) involved. Primary hepatocytes can also be used to assess biliary clearance to enable improved hepatic clearance predictions. Newer technologies such as siRNA can be used to knock out specific transporters for more predictive evaluations of potential clinically-based drug-drug interactions. In vitro safety (toxicology) studies have historically been conducted using cell lines. There is increasing evidence that co-cultures of primary hepatocytes and Kupffer cells would be more predictive of the in vivo outcome, as this system provides the complete complement of drug metabolizing enzymes, transcription factors and cytokines necessary to get a more in vivo-like toxicological response. In this review, we will discuss standard and novel in vitro approaches for using primary hepatocytes to extrapolate clinical

  13. Hepatic Xenobiotic Metabolizing Enzyme Gene Expression ...

    EPA Pesticide Factsheets

    BACKGROUND: Differences in responses to environmental chemicals and drugs between life stages are likely due in part to differences in the expression of xenobiotic metabolizing enzymes and transporters (XMETs). No comprehensive analysis of the mRNA expression of XMETs has been carried out through life stages in any species. RESULTS: Using full-genome arrays, the mRNA expression of all XMETs and their regulatory proteins was examined during fetal (gestation day (GD) 19), neonatal (postnatal day (PND) 7), prepubescent (PND32), middle age (12 months), and old age (18 and 24 months) in the C57BL/6J (C57) mouse liver and compared to adults. Fetal and neonatal life stages exhibited dramatic differences in XMET mRNA expression compared to the relatively minor effects of old age. The total number of XMET probe sets that differed from adults was 636, 500, 84, 5, 43, and 102 for GD19, PND7, PND32, 12 months, 18 months and 24 months, respectively. At all life stages except PND32, under-expressed genes outnumbered over-expressed genes. The altered XMETs included those in all of the major metabolic and transport phases including introduction of reactive or polar groups (Phase I), conjugation (Phase II) and excretion (Phase III). In the fetus and neonate, parallel increases in expression were noted in the dioxin receptor, Nrf2 components and their regulated genes while nuclear receptors and regulated genes were generally down-regulated. Suppression of male-specific XMETs w

  14. Low-Turnover Drug Molecules: A Current Challenge for Drug Metabolism Scientists.

    PubMed

    Hutzler, J Matthew; Ring, Barbara J; Anderson, Shelby R

    2015-12-01

    In vitro assays using liver subcellular fractions or suspended hepatocytes for characterizing the metabolism of drug candidates play an integral role in the optimization strategy employed by medicinal chemists. However, conventional in vitro assays have limitations in their ability to predict clearance and generate metabolites for low-turnover (slowly metabolized) drug molecules. Due to a rapid loss in the activity of the drug-metabolizing enzymes, in vitro incubations are typically performed for a maximum of 1 hour with liver microsomes to 4 hours with suspended hepatocytes. Such incubations are insufficient to generate a robust metabolic response for compounds that are slowly metabolized. Thus, the challenge of accurately estimating low human clearance with confidence has emerged to be among the top challenges that drug metabolism scientists are confronted with today. In response, investigators have evaluated novel methodologies to extend incubation times and more sufficiently measure metabolism of low-turnover drugs. These methods include plated human hepatocytes in monoculture, and a novel in vitro methodology using a relay of sequential incubations with suspended cryopreserved hepatocytes. In addition, more complex in vitro cellular models, such as HepatoPac (Hepregen, Medford, MA), a micropatterned hepatocyte-fibroblast coculture system, and the HµREL (Beverley Hills, CA) hepatic coculture system, have been developed and characterized that demonstrate prolonged enzyme activity. In this review, the advantages and disadvantages of each of these in vitro methodologies as it relates to the prediction of clearance and metabolite identification will be described in an effort to provide drug metabolism scientists with the most up-to-date experimental options for dealing with the complex issue of low-turnover drug candidates.

  15. Effect of Traumatic Brain Injury, Erythropoietin, and Anakinra on Hepatic Metabolizing Enzymes and Transporters in an Experimental Rat Model.

    PubMed

    Anderson, Gail D; Peterson, Todd C; Vonder Haar, Cole; Farin, Fred M; Bammler, Theo K; MacDonald, James W; Kantor, Eric D; Hoane, Michael R

    2015-09-01

    In contrast to considerable data demonstrating a decrease in cytochrome P450 (CYP) activity in inflammation and infection, clinically, traumatic brain injury (TBI) results in an increase in CYP and UDP glucuronosyltransferase (UGT) activity. The objective of this study was to determine the effects of TBI alone and with treatment with erythropoietin (EPO) or anakinra on the gene expression of hepatic inflammatory proteins, drug-metabolizing enzymes, and transporters in a cortical contusion impact (CCI) injury model. Microarray-based transcriptional profiling was used to determine the effect on gene expression at 24 h, 72 h, and 7 days post-CCI. Plasma cytokine and liver protein concentrations of CYP2D4, CYP3A1, EPHX1, and UGT2B7 were determined. There was no effect of TBI, TBI + EPO, or TBI + anakinra on gene expression of the inflammatory factors shown to be associated with decreased expression of hepatic metabolic enzymes in models of infection and inflammation. IL-6 plasma concentrations were increased in TBI animals and decreased with EPO and anakinra treatment. There was no significant effect of TBI and/or anakinra on gene expression of enzymes or transporters known to be involved in drug disposition. TBI + EPO treatment decreased the gene expression of Cyp2d4 at 72 h with a corresponding decrease in CYP2D4 protein at 72 h and 7 days. CYP3A1 protein was decreased at 24 h. In conclusion, EPO treatment may result in a significant decrease in the metabolism of Cyp-metabolized drugs. In contrast to clinical TBI, there was not a significant effect of experimental TBI on CYP or UGT metabolic enzymes.

  16. Regulation of CYP1A1 by heavy metals and consequences for drug metabolism.

    PubMed

    Anwar-Mohamed, Anwar; Elbekai, Reem H; El-Kadi, Ayman Os

    2009-05-01

    Cytochrome P450 1A1 (CYP1A1) is a hepatic and extrahepatic enzyme that is regulated by the aryl hydrocarbon receptor signaling pathway. With the growing human exposure to heavy metals, emerging evidence suggests that heavy metals exposure alter CYP1A1 enzyme activity. Heavy metals regulate CYP1A1 at different levels of its aryl hydrocarbon receptor signaling pathway in a metal- and species-dependent manner. The importance of CYP1A1 emerges from the fact that it has been always associated with the metabolism of pro-carcinogenic compounds to highly carcinogenic metabolites. However, recently CYP1A1 has gained status along with other cytochrome P450 enzymes in the metabolism of drugs and mediating drug-drug interactions. In addition, CYP1A1 has become a therapeutic tool for the bioactivation of prodrugs, particularly cytotoxic agents. In this review, we shed light on the effect of seven heavy metals, namely arsenic, mercury, lead, cadmium, chromium, copper and vanadium, on CYP1A1 and the consequences on drug metabolism.

  17. Characterization of increased drug metabolism activity in dimethyl sulfoxide (DMSO)-treated Huh7 hepatoma cells

    PubMed Central

    Choi, S.; Sainz, B.; Corcoran, P.; Uprichard, S.; Jeong, H.

    2010-01-01

    1. The objective of this study was to characterize Huh7 cells' baseline capacity to metabolize drugs and to investigate whether the drug metabolism was enhanced upon treatment with dimethyl sulfoxide (DMSO). 2. The messenger RNA (mRNA) levels of major Phase I and Phase II enzymes were determined by quantitative real-time-polymerase chain reaction (RT-PCR), and activities of major drug-metabolizing enzymes were examined using probe drugs by analysing relevant metabolite production rates. 3. The expression levels of drug-metabolizing enzymes in control Huh7 cells were generally very low, but DMSO treatment dramatically increased the mRNA levels of most drug-metabolizing enzymes as well as other liver-specific proteins. Importantly, functionality assays confirmed concomitant increases in drug-metabolizing enzyme activity. Additionally, treatment of the Huh7 cells with 3-methylcholanthrene induced cytochrome P450 (CYP) 1A1 expression. 4. The results indicate that DMSO treatment of Huh7 cells profoundly enhances their differentiation state, thus improving the usefulness of this common cell line as an in vitro hepatocyte model. PMID:19280519

  18. Characterization of increased drug metabolism activity in dimethyl sulfoxide (DMSO)-treated Huh7 hepatoma cells.

    PubMed

    Choi, S; Sainz, B; Corcoran, P; Uprichard, S; Jeong, H

    2009-03-01

    The objective of this study was to characterize Huh7 cells' baseline capacity to metabolize drugs and to investigate whether the drug metabolism was enhanced upon treatment with dimethyl sulfoxide (DMSO). The messenger RNA (mRNA) levels of major Phase I and Phase II enzymes were determined by quantitative real-time-polymerase chain reaction (RT-PCR), and activities of major drug-metabolizing enzymes were examined using probe drugs by analysing relevant metabolite production rates. The expression levels of drug-metabolizing enzymes in control Huh7 cells were generally very low, but DMSO treatment dramatically increased the mRNA levels of most drug-metabolizing enzymes as well as other liver-specific proteins. Importantly, functionality assays confirmed concomitant increases in drug-metabolizing enzyme activity. Additionally, treatment of the Huh7 cells with 3-methylcholanthrene induced cytochrome P450 (CYP) 1A1 expression. The results indicate that DMSO treatment of Huh7 cells profoundly enhances their differentiation state, thus improving the usefulness of this common cell line as an in vitro hepatocyte model.

  19. Computational prediction of human drug metabolism.

    PubMed

    Ekins, Sean; Andreyev, Sergey; Ryabov, Andy; Kirillov, Eugene; Rakhmatulin, Eugene A; Bugrim, Andrej; Nikolskaya, Tatiana

    2005-08-01

    There is an urgent requirement within the pharmaceutical and biotechnology industries, regulatory authorities and academia to improve the success of molecules that are selected for clinical trials. Although absorption, distribution, metabolism, excretion and toxicity (ADME/Tox) properties are some of the many components that contribute to successful drug discovery and development, they represent factors for which we currently have in vitro and in vivo data that can be modelled computationally. Understanding the possible toxicity and the metabolic fate of xenobiotics in the human body is particularly important in early drug discovery. There is, therefore, a need for computational methodologies for uncovering the relationships between the structure and the biological activity of novel molecules. The convergence of numerous technologies, including high-throughput techniques, databases, ADME/Tox modelling and systems biology modelling, is leading to the foundation of systems-ADME/Tox. Results from experiments can be integrated with predictions to globally simulate and understand the likely complete effects of a molecule in humans. The development and early application of major components of MetaDrug (GeneGo, Inc.) software will be described, which includes rule-based metabolite prediction, quantitative structure-activity relationship models for major drug metabolising enzymes, and an extensive database of human protein-xenobiotic interactions. This represents a combined approach to predicting drug metabolism. MetaDrug can be readily used for visualising Phase I and II metabolic pathways, as well as interpreting high-throughput data derived from microarrays as networks of interacting objects. This will ultimately aid in hypothesis generation and the early triaging of molecules likely to have undesirable predicted properties or measured effects on key proteins and cellular functions.

  20. Hepatocytes--the choice to investigate drug metabolism and toxicity in man: in vitro variability as a reflection of in vivo.

    PubMed

    Gómez-Lechón, María José; Castell, José Vicente; Donato, María Teresa

    2007-05-20

    The pharmaceutical industry is committed to marketing safer drugs with fewer side effects, predictable pharmacokinetic properties and quantifiable drug-drug interactions. Drug metabolism is a major determinant of drug clearance and interindividual pharmacokinetic differences, and an indirect determinant of the clinical efficacy and toxicity of drugs. Progressive advances in the knowledge of metabolic routes and enzymes responsible for drug biotransformation have contributed to understanding the great metabolic variations existing in human beings. Phenotypic as well genotypic differences in the expression of the enzymes involved in drug metabolism are the main causes of this variability. However, only a minor part of phenotypic variability in man is attributable to gene polymorphisms, thus making the definition of a normal liver complex. At present, the use of human in vitro hepatic models at early preclinical stages means that the process of selecting drug candidates is becoming much more rational. Cultured human hepatocytes are considered to be the closest model to human liver. However, the fact that hepatocytes are located in a microenvironment that differs from that of the cell in the liver raises the question: to what extent does drug metabolism variability observed in vitro actually reflect that of the liver in vivo? By comparing the metabolism of a model compound both in vitro and in vivo in the same individual, a good correlation between the in vitro and in vivo relative abundance of oxidized metabolites and the hydrolysis of the compound was observed. Thus, it is reasonable to consider that the variability observed in human hepatocytes reflects the existing phenotypic heterogeneity of the P450 expression in human liver.

  1. Large-scale multiplex absolute protein quantification of drug-metabolizing enzymes and transporters in human intestine, liver, and kidney microsomes by SWATH-MS: Comparison with MRM/SRM and HR-MRM/PRM.

    PubMed

    Nakamura, Kenji; Hirayama-Kurogi, Mio; Ito, Shingo; Kuno, Takuya; Yoneyama, Toshihiro; Obuchi, Wataru; Terasaki, Tetsuya; Ohtsuki, Sumio

    2016-08-01

    The purpose of the present study was to examine simultaneously the absolute protein amounts of 152 membrane and membrane-associated proteins, including 30 metabolizing enzymes and 107 transporters, in pooled microsomal fractions of human liver, kidney, and intestine by means of SWATH-MS with stable isotope-labeled internal standard peptides, and to compare the results with those obtained by MRM/SRM and high resolution (HR)-MRM/PRM. The protein expression levels of 27 metabolizing enzymes, 54 transporters, and six other membrane proteins were quantitated by SWATH-MS; other targets were below the lower limits of quantitation. Most of the values determined by SWATH-MS differed by less than 50% from those obtained by MRM/SRM or HR-MRM/PRM. Various metabolizing enzymes were expressed in liver microsomes more abundantly than in other microsomes. Ten, 13, and eight transporters listed as important for drugs by International Transporter Consortium were quantified in liver, kidney, and intestinal microsomes, respectively. Our results indicate that SWATH-MS enables large-scale multiplex absolute protein quantification while retaining similar quantitative capability to MRM/SRM or HR-MRM/PRM. SWATH-MS is expected to be useful methodology in the context of drug development for elucidating the molecular mechanisms of drug absorption, metabolism, and excretion in the human body based on protein profile information.

  2. Clinical review: Drug metabolism and nonrenal clearance in acute kidney injury

    PubMed Central

    Vilay, A Mary; Churchwell, Mariann D; Mueller, Bruce A

    2008-01-01

    Decreased renal drug clearance is an obvious consequence of acute kidney injury (AKI). However, there is growing evidence to suggest that nonrenal drug clearance is also affected. Data derived from human and animal studies suggest that hepatic drug metabolism and transporter function are components of nonrenal clearance affected by AKI. Acute kidney injury may also impair the clearance of formed metabolites. The fact that AKI does not solely influence kidney function may have important implications for drug dosing, not only of renally eliminated drugs but also of those that are hepatically cleared. A review of the literature addressing the topic of drug metabolism and clearance alterations in AKI reveals that changes in nonrenal clearance are highly complicated and poorly studied, but they may be quite common. At present, our understanding of how AKI affects drug metabolism and nonrenal clearance is limited. However, based on the available evidence, clinicians should be cognizant that even hepatically eliminated drugs and formed drug metabolites may accumulate during AKI, and renal replacement therapy may affect nonrenal clearance as well as drug metabolite clearance. PMID:19040780

  3. Novel aspects of drug metabolism and transport.

    PubMed

    Afzelius, Lovisa; Ingelman-Sundberg, Magnus; Karlgren, Maria; Rodriguez-Antona, Cristina

    2006-12-01

    The 16th International Symposium on Microsomes and Drug Oxidations (MDO2006) in Budapest, Hungary, had almost 400 attendees and was nicely organized by Laszlo Vereczkey and colleagues. The meeting had a very high standard in the field of drug metabolism, drug transport and related areas and in addition, the social events were much appreciated. At the meeting 70 invited lectures were presented in plenary sessions and in three parallel symposia sessions, and about 178 posters were shown, among them 26 posters in the young investigators workshop. The review herein is given of a majority (57) of the lectures presented at the Symposium.

  4. Nuclear Receptors in Drug Metabolism, Drug Response and Drug Interactions

    PubMed Central

    Prakash, Chandra; Zuniga, Baltazar; Song, Chung Seog; Jiang, Shoulei; Cropper, Jodie; Park, Sulgi; Chatterjee, Bandana

    2016-01-01

    Orally delivered small-molecule therapeutics are metabolized in the liver and intestine by phase I and phase II drug-metabolizing enzymes (DMEs), and transport proteins coordinate drug influx (phase 0) and drug/drug-metabolite efflux (phase III). Genes involved in drug metabolism and disposition are induced by xenobiotic-activated nuclear receptors (NRs), i.e. PXR (pregnane X receptor) and CAR (constitutive androstane receptor), and by the 1α, 25-dihydroxy vitamin D3-activated vitamin D receptor (VDR), due to transactivation of xenobiotic-response elements (XREs) present in phase 0-III genes. Additional NRs, like HNF4-α, FXR, LXR-α play important roles in drug metabolism in certain settings, such as in relation to cholesterol and bile acid metabolism. The phase I enzymes CYP3A4/A5, CYP2D6, CYP2B6, CYP2C9, CYP2C19, CYP1A2, CYP2C8, CYP2A6, CYP2J2, and CYP2E1 metabolize >90% of all prescription drugs, and phase II conjugation of hydrophilic functional groups (with/without phase I modification) facilitates drug clearance. The conjugation step is mediated by broad-specificity transferases like UGTs, SULTs, GSTs. This review delves into our current understanding of PXR/CAR/VDR-mediated regulation of DME and transporter expression, as well as effects of single nucleotide polymorphism (SNP) and epigenome (specified by promoter methylation, histone modification, microRNAs, long non coding RNAs) on the expression of PXR/CAR/VDR and phase 0-III mediators, and their impacts on variable drug response. Therapeutic agents that target epigenetic regulation and the molecular basis and consequences (overdosing, underdosing, or beneficial outcome) of drug-drug/drug-food/drug-herb interactions are also discussed. Precision medicine requires understanding of a drug’s impact on DME and transporter activity and their NR-regulated expression in order to achieve optimal drug efficacy without adverse drug reactions. In future drug screening, new tools such as humanized mouse models and

  5. Nuclear Receptors in Drug Metabolism, Drug Response and Drug Interactions.

    PubMed

    Prakash, Chandra; Zuniga, Baltazar; Song, Chung Seog; Jiang, Shoulei; Cropper, Jodie; Park, Sulgi; Chatterjee, Bandana

    Orally delivered small-molecule therapeutics are metabolized in the liver and intestine by phase I and phase II drug-metabolizing enzymes (DMEs), and transport proteins coordinate drug influx (phase 0) and drug/drug-metabolite efflux (phase III). Genes involved in drug metabolism and disposition are induced by xenobiotic-activated nuclear receptors (NRs), i.e. PXR (pregnane X receptor) and CAR (constitutive androstane receptor), and by the 1α, 25-dihydroxy vitamin D3-activated vitamin D receptor (VDR), due to transactivation of xenobiotic-response elements (XREs) present in phase 0-III genes. Additional NRs, like HNF4-α, FXR, LXR-α play important roles in drug metabolism in certain settings, such as in relation to cholesterol and bile acid metabolism. The phase I enzymes CYP3A4/A5, CYP2D6, CYP2B6, CYP2C9, CYP2C19, CYP1A2, CYP2C8, CYP2A6, CYP2J2, and CYP2E1 metabolize >90% of all prescription drugs, and phase II conjugation of hydrophilic functional groups (with/without phase I modification) facilitates drug clearance. The conjugation step is mediated by broad-specificity transferases like UGTs, SULTs, GSTs. This review delves into our current understanding of PXR/CAR/VDR-mediated regulation of DME and transporter expression, as well as effects of single nucleotide polymorphism (SNP) and epigenome (specified by promoter methylation, histone modification, microRNAs, long non coding RNAs) on the expression of PXR/CAR/VDR and phase 0-III mediators, and their impacts on variable drug response. Therapeutic agents that target epigenetic regulation and the molecular basis and consequences (overdosing, underdosing, or beneficial outcome) of drug-drug/drug-food/drug-herb interactions are also discussed. Precision medicine requires understanding of a drug's impact on DME and transporter activity and their NR-regulated expression in order to achieve optimal drug efficacy without adverse drug reactions. In future drug screening, new tools such as humanized mouse models and

  6. High-throughput screening to estimate single or multiple enzymes involved in drug metabolism: microtitre plate assay using a combination of recombinant CYP2D6 and human liver microsomes.

    PubMed

    Yamamoto, T; Suzuki, A; Kohno, Y

    2003-08-01

    1. The purpose of this study was to estimate readily involvement of single or multiple enzymes in the metabolism of a drug through inhibitory assessment. Inhibitory effects of various compounds on CYP2D6 activity assayed by formation of fluorescent metabolite from 3-[2-(N,N-diethyl-N-methyl-ammonium)ethyl]-7-methoxy-4-methyl-coumarin (AMMC) were assessed using microtitre plate (MTP) assays with a combination of recombinant CYP2D6 and human liver microsomes (HLM). 2. Among various compounds studied, antipsychotic drugs extensively inhibited recombinant CYP2D6 activity and the IC50 values were generally lower than those of antidepressants and antiarrhythmic drugs. 3. After pre-incubation, the IC50 values of mianserin, chlorpromadine, risperidone, thioridazine, alprenolol, propafenone and dextromethorphan increased but the values of timolol, S-metoprolol and propranolol substantially decreased compared with those in case of co-incubation. 4. The IC50 values of typical substrates of CYP2D6 (bufuralol and dextromethorphan at lower substrate concentration) in inhibition studies using HLM, were similar to those in the case of recombinant CYP2D6, but the values of the compounds that are metabolized by multiple CYP forms (perphenazine and chlorpromazine) in HLM were much larger. 5. If the ratio (HLM/rCYP ratio) of IC50 values between HLM and recombinant CYP2D6 exceeds approximately 2, it suggests that other CYP forms in addition to CYP2D6 might be involved in the metabolism of the test compounds. From the advantage such as speed, high throughput and ease of the technique, the MTP assay using a combination of the recombinant CYP2D6 and HLM is useful to estimate the involvement of single or multiple enzymes in the metabolism of drugs at the stage of drug discovery.

  7. Functional crosstalk of CAR-LXR and ROR-LXR in drug metabolism and lipid metabolism.

    PubMed

    Xiao, Lei; Xie, Xinni; Zhai, Yonggong

    2010-10-30

    Nuclear receptor crosstalk represents an important mechanism to expand the functions of individual receptors. The liver X receptors (LXR, NR1H2/3), both the α and β isoforms, are nuclear receptors that can be activated by the endogenous oxysterols and other synthetic agonists. LXRs function as cholesterol sensors, which protect mammals from cholesterol overload. LXRs have been shown to regulate the expression of a battery of metabolic genes, especially those involved in lipid metabolism. LXRs have recently been suggested to play a novel role in the regulation of drug metabolism. The constitutive androstane receptor (CAR, NR1I3) is a xenobiotic receptor that regulates the expression of drug-metabolizing enzymes and transporters. Disruption of CAR alters sensitivity to toxins, increasing or decreasing it depending on the compounds. More recently, additional roles for CAR have been discovered. These include the involvement of CAR in lipid metabolism. Mechanistically, CAR forms an intricate regulatory network with other members of the nuclear receptor superfamily, foremost the LXRs, in exerting its effect on lipid metabolism. Retinoid-related orphan receptors (RORs, NR1F1/2/3) have three isoforms, α, β and γ. Recent reports have shown that loss of RORα and/or RORγ can positively or negatively influence the expression of multiple drug-metabolizing enzymes and transporters in the liver. The effects of RORs on expression of drug-metabolizing enzymes were reasoned to be, at least in part, due to the crosstalk with LXR. This review focuses on the CAR-LXR and ROR-LXR crosstalk, and the implications of this crosstalk in drug metabolism and lipid metabolism.

  8. Human carboxylesterase 1: from drug metabolism to drug discovery.

    PubMed

    Redinbo, M R; Bencharit, S; Potter, P M

    2003-06-01

    Human carboxylesterase 1 (hCE1) is a serine esterase involved in both drug metabolism and activation, as well as other biological processes. hCE1 catalyses the hydrolysis of heroin and cocaine, and the transesterification of cocaine in the presence of ethanol to the toxic metabolite cocaethylene. We have determined the crystal structures of hCE1 in complex with either the cocaine analogue homatropine or the heroin analogue naloxone. These are the first structures of a human carboxylesterase, and they provide details about narcotic metabolism in humans. hCE1's active site contains rigid and flexible pockets, explaining the enzyme's ability to act both specifically and promiscuously. hCE1 has also been reported to contain cholesteryl ester hydrolase, fatty acyl-CoA hydrolase and acyl-CoA:cholesterol acyltransferase activities, and thus appears to be involved in cholesterol metabolism. Since the enzyme may be useful as a treatment for cocaine overdose, and may afford protection against chemical weapons like Sarin, Soman and VX gas, hCE1 could serve as both a drug and a drug target. Selective hCE1 inhibitors targeted to several sites on the enzyme may also pave the way for novel clinical tools to manage cholesterol homoeostasis in humans.

  9. Drug metabolism in human brain: high levels of cytochrome P4503A43 in brain and metabolism of anti-anxiety drug alprazolam to its active metabolite.

    PubMed

    Agarwal, Varsha; Kommaddi, Reddy P; Valli, Khader; Ryder, Daniel; Hyde, Thomas M; Kleinman, Joel E; Strobel, Henry W; Ravindranath, Vijayalakshmi

    2008-06-11

    Cytochrome P450 (P450) is a super-family of drug metabolizing enzymes. P450 enzymes have dual function; they can metabolize drugs to pharmacologically inactive metabolites facilitating their excretion or biotransform them to pharmacologically active metabolites which may have longer half-life than the parent drug. The variable pharmacological response to psychoactive drugs typically seen in population groups is often not accountable by considering dissimilarities in hepatic metabolism. Metabolism in brain specific nuclei may play a role in pharmacological modulation of drugs acting on the CNS and help explain some of the diverse response to these drugs seen in patient population. P450 enzymes are also present in brain where drug metabolism can take place and modify therapeutic action of drugs at the site of action. We have earlier demonstrated an intrinsic difference in the biotransformation of alprazolam (ALP) in brain and liver, relatively more alpha-hydroxy alprazolam (alpha-OHALP) is formed in brain as compared to liver. In the present study we show that recombinant CYP3A43 metabolizes ALP to both alpha-OHALP and 4-hydroxy alprazolam (4-OHALP) while CYP3A4 metabolizes ALP predominantly to its inactive metabolite, 4-OHALP. The expression of CYP3A43 mRNA in human brain samples correlates with formation of relatively higher levels of alpha-OH ALP indicating that individuals who express higher levels of CYP3A43 in the brain would generate larger amounts of alpha-OHALP. Further, the expression of CYP3A43 was relatively higher in brain as compared to liver across different ethnic populations. Since CYP3A enzymes play a prominent role in the metabolism of drugs, the higher expression of CYP3A43 would generate metabolite profile of drugs differentially in human brain and thus impact the pharmacodynamics of psychoactive drugs at the site of action.

  10. Effect of Helicteres isora bark extract on blood glucose and hepatic enzymes in experimental diabetes.

    PubMed

    Kumar, G; Murugesan, A G; Rajasekara Pandian, M

    2006-04-01

    The effect of oral administration of an aqueous extract of the bark of Helicteres isora was investigated on blood glucose and plasma antioxidant status in streptozotocin (STZ) induced diabetic rats. The study was also undertaken to evaluate the role of hepatic enzymes in experimental diabetes. Oral administration of a bark extract of Helicteres isora (100, 200 mg/kg) in STZ diabetic rats caused a significant increase in body weight, hepatic hexokinase activity and significant decrease in hepatic glucose-6-phosphatase, serum acid phosphatase (ACP), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH). Based on these findings, we suggest that Helicteres isora possesses hypoglycemic and hepatoprotective activity and is able to ameliorate biochemical damage in STZ induced diabetic rats.

  11. Can vaccines interact with drug metabolism?

    PubMed

    Pellegrino, Paolo; Clementi, Emilio; Capuano, Annalisa; Radice, Sonia

    2015-02-01

    Vaccines are safe and efficacious in reducing the burden of several serious infections affecting children and adults. Due to their efficacy, vaccines are often administered in patients with chronic diseases, likely to be under poly-therapy. Because of several case reports indicating changes in drug metabolism after vaccination, the hypothesis of an interaction between vaccines and specific drugs has been put forward. These interactions are conceivably of great concern, especially in patients treated with molecules characterised by a narrow therapeutic index. Herein, we review and systematise the available evidence on vaccine-drug interactions. The picture that emerges indicates that reduction in the activity of specific CYPs following vaccination may occur, most likely via interferon γ overproduction, and for specific drugs such as anticonvulsivant and theophylline may have significant clinical relevance. Clinical interaction between vaccines and drugs that are metabolised by cytochromes uninfluenced by INFγ levels, such as warfarin, are instead unlikely to happen. Further studies are however needed to gain a complete picture of vaccine-drug interactions and define their relevance in terms of possible negative clinical impact.

  12. Naturalistic observation on the hepatic enzyme changes in patients treated with either risperidone or olanzapine alone.

    PubMed

    Pae, Chi-Un; Lim, Hyun-Kook; Kim, Tae-Suk; Kim, Jung-Jin; Lee, Chang-Uk; Lee, Soo-Jung; Lee, Chul; Paik, In-Ho

    2005-05-01

    This retrospective study aimed to compare differences in hepatic enzyme elevation during treatment with either risperidone or olanzapine alone in patients with psychotic disorders. The charts were reviewed for six hundred and sixty-seven (667) inpatients with psychotic disorders who were treated with either risperidone (n=289) or olanzapine (n=145) alone at a university-affiliated hospital between 1998 and 2002. Frequencies of elevation greater than the reference level in any enzyme among aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphotase (ALP) were higher in the olanzapine-treated group (26.9%) than in the risperidone-treated group (14.2%) [odds ratio (OR)=2.225, 95% confidence interval (CI)=1.362-3.638, P=0.002]. Frequencies of elevation greater than the reference level in ALT were higher in the olanzapine-treated group than in the risperidone-treated group (OR=2.182, P=0.004), as were frequencies with two-fold (OR=3.064, P=0.017) and three-fold (OR=2.883, P=0.039) elevation. Recovery time was longer in the olanzapine-treated group than in the risperidone-treated group (P=0.0059), as was latency time (P=0.0044). These results suggest that there are potential differences in antipsychotic-associated hepatic enzyme alterations between risperidone and olanzapine treatment. Controlled, prospective studies should be conducted to identify the risk factors associated with an alteration in hepatic enzymes related to treatment with risperidone and olanzapine.

  13. Activities of the enzymes of hepatic gluconeogenesis in periparturient dairy cows with induced fatty liver.

    PubMed

    Murondoti, Absolom; Jorritsma, Ruurd; Beynen, Anton C; Wensing, Theo; Geelen, Math J H

    2004-05-01

    The objective was to measure the activities of all the enzymes essential for hepatic gluconeogenesis in dairy cows with induced fatty liver. We aimed to induce severe fatty liver in ten experimental cows by overfeeding them during the dry period while seven control cows were maintained on a restricted diet. To induce a marked negative energy balance, the experimental cows were deprived of feed for 8 h immediately after parturition. In addition, the experimental cows were given a restricted amount of diet during the first 5 d of lactation. Liver samples were collected 1 week before and 1, 2 and 4 weeks after parturition. Before parturition, liver triacylglycerol concentrations did not differ between the two groups. After parturition, the experimental cows developed marked fatty liver as indicated by a higher level of triacylglycerols in the liver compared with the control cows. Before parturition, all gluconeogenic enzymes in the liver were lower in experimental cows than in control cows. Phosphoenolpyruvate carboxykinase, pyruvate carboxylase and propionyl-CoA carboxylase were significantly lower and fructose 1,6-bisphosphatase and glucose 6-phosphatase tended to be lower in the experimental cows. The activities of two crucial enzymes for gluconeogenesis in ruminants, i.e., phosphoenolpyruvate carboxykinase and propionyl-CoA carboxylase, remained low throughout the sampling period post partum. Activities of pyruvate carboxylase and glucose 6-phosphatase in the experimental cows post partum were upgraded to values similar to those of the control cows. The results showed that the capacity for hepatic gluconeogenesis before parturition was lower in cows with induced fatty liver than in control cows. After parturition, the low activities of crucial gluconeogenic enzymes indicated insufficient production of glucose. It is suggested that the low gluconeogenic capacity leads successively to low blood glucose concentrations, low insulin levels and high rates of

  14. PXR variants: the impact on drug metabolism and therapeutic responses.

    PubMed

    Brewer, C Trent; Chen, Taosheng

    2016-09-01

    The pregnane X receptor (PXR) plays an important and diverse role in mediating xenobiotic induction of drug-metabolizing enzymes and transporters. Several protein isoforms of PXR exist, and they have differential transcriptional activity upon target genes; transcript variants 3 (PXR3) and 4 (PXR4) do not induce target gene expression, whereas transcript variants 1 (PXR1) and 2 (PXR2) respond to agonist by activating target gene expression. PXR protein variants also display differences in protein-protein interactions; PXR1 interacts with p53, whereas PXR3 does not. Furthermore, the transcript variants of PXR that encode these protein isoforms are differentially regulated by methylation and deletions in the respective promoters of the variants, and their expression differs in various human cancers and also in cancerous tissue compared to adjacent normal tissues. PXR1 and PXR4 mRNA are downregulated by methylation in cancerous tissue and have divergent effects on cellular proliferation when ectopically overexpressed. Additional detailed and comparative mechanistic studies are required to predict the effect of PXR transcript variant expression on carcinogenesis, therapeutic response, and the development of toxicity.

  15. Acute Liver Injury Induces Nucleocytoplasmic Redistribution of Hepatic Methionine Metabolism Enzymes

    PubMed Central

    Delgado, Miguel; Garrido, Francisco; Pérez-Miguelsanz, Juliana; Pacheco, María; Partearroyo, Teresa; Pérez-Sala, Dolores

    2014-01-01

    Abstract Aims: The discovery of methionine metabolism enzymes in the cell nucleus, together with their association with key nuclear processes, suggested a putative relationship between alterations in their subcellular distribution and disease. Results: Using the rat model of d-galactosamine intoxication, severe changes in hepatic steady-state mRNA levels were found; the largest decreases corresponded to enzymes exhibiting the highest expression in normal tissue. Cytoplasmic protein levels, activities, and metabolite concentrations suffered more moderate changes following a similar trend. Interestingly, galactosamine treatment induced hepatic nuclear accumulation of methionine adenosyltransferase (MAT) α1 and S-adenosylhomocysteine hydrolase tetramers, their active assemblies. In fact, galactosamine-treated livers showed enhanced nuclear MAT activity. Acetaminophen (APAP) intoxication mimicked most galactosamine effects on hepatic MATα1, including accumulation of nuclear tetramers. H35 cells that overexpress tagged-MATα1 reproduced the subcellular distribution observed in liver, and the changes induced by galactosamine and APAP that were also observed upon glutathione depletion by buthionine sulfoximine. The H35 nuclear accumulation of tagged-MATα1 induced by these agents correlated with decreased glutathione reduced form/glutathione oxidized form ratios and was prevented by N-acetylcysteine (NAC) and glutathione ethyl ester. However, the changes in epigenetic modifications associated with tagged-MATα1 nuclear accumulation were only prevented by NAC in galactosamine-treated cells. Innovation: Cytoplasmic and nuclear changes in proteins that regulate the methylation index follow opposite trends in acute liver injury, their nuclear accumulation showing potential as disease marker. Conclusion: Altogether these results demonstrate galactosamine- and APAP-induced nuclear accumulation of methionine metabolism enzymes as active oligomers and unveil the implication of

  16. Hepatic biotransformation and antioxidant enzyme activities in Mediterranean fish from different habitat depths.

    PubMed

    Ribalta, C; Sanchez-Hernandez, J C; Sole, M

    2015-11-01

    Marine fish are threatened by anthropogenic chemical discharges. However, knowledge on adverse effects on deep-sea fish or their detoxification capabilities is limited. Herein, we compared the basal activities of selected hepatic detoxification enzymes in several species (Solea solea, Dicentrarchus labrax, Trachyrhynchus scabrus, Mora moro, Cataetix laticeps and Alepocehalus rostratus) collected from the coast, middle and lower slopes of the Blanes Canyon region (Catalan continental margin, NW Mediterranean Sea). The xenobiotic-detoxifying enzymes analysed were the phase-I carboxylesterases (CbEs), and the phase-II conjugation activities uridine diphosphate glucuronyltransferase (UDPGT) and glutathione S-transferase (GST). Moreover, some antioxidant enzyme activities, i.e., catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR), were also included in this comparative study. Because CbE activity is represented by multiple isoforms, the substrates α-naphthyl acetate (αNA) and ρ-nitrophenyl acetate (ρNPA) were used in the enzyme assays, and in vitro inhibition kinetics with dichlorvos were performed to compare interspecific CbE sensitivity. Activity of xenobiotic detoxification enzymes varied among the species, following a trend with habitat depth and body size. Thus, UDPGT and some antioxidant enzyme activities decreased in fish inhabiting lower slopes of deep-sea, whereas UDPGT and αNA-CbE activities were negatively related to fish size. A trend between CbE activities and the IC50 values for dichlorvos suggested S. solea and M. moro as potentially more sensitive to anticholinesterasic pesticides, and T. scabrus as the most resistant one. A principal component analysis considering all enzyme activities clearly identified the species but this grouping was not related to habitat depth or phylogeny. Although these results can be taken as baseline levels of the main xenobiotic detoxification enzymes in Mediterranean fish, further research is

  17. Predicting drug metabolism: experiment and/or computation?

    PubMed

    Kirchmair, Johannes; Göller, Andreas H; Lang, Dieter; Kunze, Jens; Testa, Bernard; Wilson, Ian D; Glen, Robert C; Schneider, Gisbert

    2015-06-01

    Drug metabolism can produce metabolites with physicochemical and pharmacological properties that differ substantially from those of the parent drug, and consequently has important implications for both drug safety and efficacy. To reduce the risk of costly clinical-stage attrition due to the metabolic characteristics of drug candidates, there is a need for efficient and reliable ways to predict drug metabolism in vitro, in silico and in vivo. In this Perspective, we provide an overview of the state of the art of experimental and computational approaches for investigating drug metabolism. We highlight the scope and limitations of these methods, and indicate strategies to harvest the synergies that result from combining measurement and prediction of drug metabolism.

  18. Hepatitis

    MedlinePlus

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Hepatitis KidsHealth > For Teens > Hepatitis Print A A A ... to a liver condition called hepatitis . What Is Hepatitis? The liver is one of the body's powerhouses. ...

  19. Hepatitis

    MedlinePlus

    ... de los dientes Video: Getting an X-ray Hepatitis KidsHealth > For Kids > Hepatitis Print A A A ... an important digestive liquid called bile . What Is Hepatitis? Hepatitis is an inflammation (say: in-fluh-MAY- ...

  20. Effect of peppermint oil on serum lipid peroxidation and hepatic enzymes after immobility stress in mice.

    PubMed

    Marjani, Abdoljalal; Rahmati, Reza; Mansourian, Azad Reza; Veghary, Gholamreza

    2012-01-01

    This study was undertaken to determine the influences of various doses of peppermint oil on the hepatic en-zymes, alanine transaminase, apartate tranaminase, alkaline phosphotase and gamma glutamyl transferase and the level of malondialdehyde in the serum of mice with and without immobility stress. The mice exposed to drink water, 0.9, 27 and 60 mg/kg peppermint oil from the days 1 to 5 for a period of 4 h before and after immobility stress. Serum MDA in-creased in treatment group II, III and IV after immobility stress. There was a significant decrease in ALT in treatment group III and IV after immobility stress. There were also significant decreases in ALP and GGT in treatment group IV af-ter immobility stress. This result may suggest that, MDA level is higher in immobilization stress group than in the un-immobilized animals in serum and this results show that enzyme activities decreased after immobilization stress.

  1. Interindividual Variability in Cytochrome P450–Mediated Drug Metabolism

    PubMed Central

    Tracy, Timothy S.; Chaudhry, Amarjit S.; Prasad, Bhagwat; Thummel, Kenneth E.; Schuetz, Erin G.; Zhong, Xiao-bo; Tien, Yun-Chen; Pan, Xian; Shireman, Laura M.; Tay-Sontheimer, Jessica; Lin, Yvonne S.

    2016-01-01

    The cytochrome P450 (P450) enzymes are the predominant enzyme system involved in human drug metabolism. Alterations in the expression and/or activity of these enzymes result in changes in pharmacokinetics (and consequently the pharmacodynamics) of drugs that are metabolized by this set of enzymes. Apart from changes in activity as a result of drug–drug interactions (by P450 induction or inhibition), the P450 enzymes can exhibit substantial interindividual variation in basal expression and/or activity, leading to differences in the rates of drug elimination and response. This interindividual variation can result from a myriad of factors, including genetic variation in the promoter or coding regions, variation in transcriptional regulators, alterations in microRNA that affect P450 expression, and ontogenic changes due to exposure to xenobiotics during the developmental and early postnatal periods. Other than administering a probe drug or cocktail of drugs to obtain the phenotype or conducting a genetic analysis to determine genotype, methods to determine interindividual variation are limited. Phenotyping via a probe drug requires exposure to a xenobiotic, and genotyping is not always well correlated with phenotype, making both methodologies less than ideal. This article describes recent work evaluating the effect of some of these factors on interindividual variation in human P450-mediated metabolism and the potential utility of endogenous probe compounds to assess rates of drug metabolism among individuals. PMID:26681736

  2. Xenobiotic-sensing nuclear receptors involved in drug metabolism: a structural perspective.

    PubMed

    Wallace, Bret D; Redinbo, Matthew R

    2013-02-01

    Xenobiotic compounds undergo a critical range of biotransformations performed by the phase I, II, and III drug-metabolizing enzymes. The oxidation, conjugation, and transportation of potentially harmful xenobiotic and endobiotic compounds achieved by these catalytic systems are significantly regulated, at the gene expression level, by members of the nuclear receptor (NR) family of ligand-modulated transcription factors. Activation of NRs by a variety of endo- and exogenous chemicals are elemental to induction and repression of drug-metabolism pathways. The master xenobiotic sensing NRs, the promiscuous pregnane X receptor and less-promiscuous constitutive androstane receptor are crucial to initial ligand recognition, jump-starting the metabolic process. Other receptors, including farnesoid X receptor, vitamin D receptor, hepatocyte nuclear factor 4 alpha, peroxisome proliferator activated receptor, glucocorticoid receptor, liver X receptor, and RAR-related orphan receptor, are not directly linked to promiscuous xenobiotic binding, but clearly play important roles in the modulation of metabolic gene expression. Crystallographic studies of the ligand-binding domains of nine NRs involved in drug metabolism provide key insights into ligand-based and constitutive activity, coregulator recruitment, and gene regulation. Structures of other, noncanonical transcription factors also shed light on secondary, but important, pathways of control. Pharmacological targeting of some of these nuclear and atypical receptors has been instituted as a means to treat metabolic and developmental disorders and provides a future avenue to be explored for other members of the xenobiotic-sensing NRs.

  3. IDSite: An accurate approach to predict P450-mediated drug metabolism

    PubMed Central

    Li, Jianing; Schneebeli, Severin T.; Bylund, Joseph; Farid, Ramy; Friesner, Richard A.

    2011-01-01

    Accurate prediction of drug metabolism is crucial for drug design. Since a large majority of drugs metabolism involves P450 enzymes, we herein describe a computational approach, IDSite, to predict P450-mediated drug metabolism. To model induced-fit effects, IDSite samples the conformational space with flexible docking in Glide followed by two refinement stages using the Protein Local Optimization Program (PLOP). Sites of metabolism (SOMs) are predicted according to a physical-based score that evaluates the potential of atoms to react with the catalytic iron center. As a preliminary test, we present in this paper the prediction of hydroxylation and O-dealkylation sites mediated by CYP2D6 using two different models: a physical-based simulation model, and a modification of this model in which a small number of parameters are fit to a training set. Without fitting any parameters to experimental data, the Physical IDSite scoring recovers 83% of the experimental observations for 56 compounds with a very low false positive rate. With only 4 fitted parameters, the Fitted IDSite was trained with the subset of 36 compounds and successfully applied to the other 20 compounds, recovering 94% of the experimental observations with high sensitivity and specificity for both sets. PMID:22247702

  4. Electrochemistry in the mimicry of oxidative drug metabolism by cytochrome P450s.

    PubMed

    Nouri-Nigjeh, Eslam; Bischoff, Rainer; Bruins, Andries P; Permentier, Hjalmar P

    2011-05-01

    Prediction of oxidative drug metabolism at the early stages of drug discovery and development requires fast and accurate analytical techniques to mimic the in vivo oxidation reactions by cytochrome P450s (CYP). Direct electrochemical oxidation combined with mass spectrometry, although limited to the oxidation reactions initiated by charge transfer, has shown promise in the mimicry of certain CYP-mediated metabolic reactions. The electrochemical approach may further be utilized in an automated manner in microfluidics devices facilitating fast screening of oxidative drug metabolism. A wide range of in vivo oxidation reactions, particularly those initiated by hydrogen atom transfer, can be imitated through the electrochemically-assisted Fenton reaction. This reaction is based on O-O bond activation in hydrogen peroxide and oxidation by hydroxyl radicals, wherein electrochemistry is used for the reduction of molecular oxygen to hydrogen peroxide, as well as the reduction of Fe(3+) to Fe(2+). Metalloporphyrins, as surrogates for the prosthetic group in CYP, utilizing metallo-oxo reactive species, can also be used in combination with electrochemistry. Electrochemical reduction of metalloporphyrins in solution or immobilized on the electrode surface activates molecular oxygen in a manner analogous to the catalytical cycle of CYP and different metalloporphyrins can mimic selective oxidation reactions. Chemoselective, stereoselective, and regioselective oxidation reactions may be mimicked using electrodes that have been modified with immobilized enzymes, especially CYP itself. This review summarizes the recent attempts in utilizing electrochemistry as a versatile analytical and preparative technique in the mimicry of oxidative drug metabolism by CYP.

  5. Study of hepatic function matching between Banna minipig inbred and humans.

    PubMed

    Zhang, L; Sun, X; Cheng, J; Wang, L; Wei, Q; Li, S; Zeng, R; Zeng, Y; Li, Y

    2004-10-01

    As a unique inbred pig Banna minipig inbred (BMI) is potentially suitable for pig-to-human xenotransplantation due to its clear genetic background and minor interindividual differences. Previous studies of BMI have focused on immunological barriers between BMI and humans. However, a comparison of liver function between donor animals and humans is an essential premise for successful xenotransplantation. In this study, we investigated routine hepatic functions, protein electrophoresis, and drug metabolism to compare capacity of liver synthesis, metabolism, and drainage between BMI and humans. The results showed no significant differences in the concentrations of albumin and globulin synthesized in the liver (alpha1, alpha2, and beta-globulin). Serum enzyme activities in BMI were higher than those in humans, and levels of total bilirubin and direct-reacting bilirubin of BMI were lower than those of humans. In BMI, the clearance of antipyrine, a widely used model drug to study hepatic drug metabolism, was 16 times greater than that by humans, with a mean residual time of antipyrine in BMI, one-tenth of that in human. These findings suggested that BMI livers are similar to humans in albumin and alpha, beta-globulin synthesis, but stronger in bilirubin elimination, enzyme activity, and drug metabolism. BMI livers may have stronger functions compared with those of humans. No incompatibility was identified in hepatic function between BMI and humans.

  6. Hesperidin a citrus bioflavonoid modulates hepatic biotransformation enzymes and enhances intrinsic antioxidants in experimental breast cancer rats challenged with 7, 12-dimethylbenz (a) anthracene.

    PubMed

    Nandakumar, Natarajan; Balasubramanian, Maruthaiveeran Periyasamy

    2012-01-01

    DMBA is a major class of potent genotoxic chemical carcinogen present in the environment and it may increase breast cancer risk. Flavonoids have been shown to have interesting biological activities in many experimental investigations. Hesperidin is one of the citrus flavonoid shown to be active against various oxidative stress mediated diseases. The aim of the present study was to investigate the beneficial impact of a natural citrus flavonoglycoside hesperidin against 7, 12-Dimethylbenz [a] anthracene challenged experimental breast carcinogenesis with reference to drug metabolizing enzymes and intrinsic antioxidant status. The female Sprague-Dawley rats were orally administered with single dose of 7, 12-DMBA to induce breast cancer and were treated with hesperidin [30mg/kg/body weight] for a consecutive 45 days. The results revealed that there was a significant reduction in the status of antioxidants levels and also significant alterations in the drug metabolizing enzymes were found in genotoxin DMBA exposed animals. Interestingly these, altered levels were significantly revered back to near normal in hesperidin administered animals via enhancing the intrinsic antioxidant levels and induction in Phase II enzymes and modulation in Phase I enzyme levels. Thus the antigenotoxic activity of hesperidin may be due to the modulatory effect in biotransformation enzymes and excellent antioxidant potentials which paving a way to consider hesperidin against the genotoxin involved oxidative stress mediated diseases.

  7. Liver Enzymes in Children with beta-Thalassemia Major: Correlation with Iron Overload and Viral Hepatitis

    PubMed Central

    Salama, Khaled M.; Ibrahim, Ola M.; Kaddah, Ahmed M.; Boseila, Samia; Ismail, Leila Abu; Hamid, May M. Abdel

    2015-01-01

    BACKGROUND: Beta Thalassemia is the most common chronic hemolytic anemia in Egypt (85.1%) with an estimated carrier rate of 9-10.2%. Injury to the liver, whether acute or chronic, eventually results in an increase in serum concentrations of Alanine transaminase (ALT) and Aspartate transaminase (AST). AIM: Evaluating the potentiating effect of iron overload & viral hepatitis infection on the liver enzymes. PATIENTS AND METHODS: Eighty (80) thalassemia major patients were studied with respect to liver enzymes, ferritin, transferrin saturation, HBsAg, anti-HCV antibody and HCV-PCR for anti-HCV positive patients. RESULTS: Fifty % of the patients were anti-HCV positive and 55% of them were HCV-PCR positive. Patients with elevated ALT and AST levels had significantly higher mean serum ferritin than those with normal levels. Anti-HCV positive patients had higher mean serum ferritin, serum ALT, AST and GGT levels and higher age and duration of blood transfusion than the negative group. HCV-PCR positive patients had higher mean serum ferritin and serum ALT and also higher age and duration of blood transfusion than the negative group. CONCLUSION: Iron overload is a main leading cause of elevated liver enzymes, and presence of HCV infection is significantly related to the increased iron overload. PMID:27275237

  8. Hepatitis

    MedlinePlus

    ... clotting problems or chronic liver disease. previous continue Hepatitis B and Hepatitis C Although hep A is a ... does — through direct contact with infected body fluids. Hepatitis B and C are even more easily passed in ...

  9. Hepatitis

    MedlinePlus

    ... A if they've been vaccinated against it. Hepatitis B Hepatitis B is a more serious infection. It may lead ... of which cause severe illness and even death. Hepatitis B virus (HBV) is transmitted from person to person ...

  10. Hepatitis

    MedlinePlus

    ... Issues Listen Español Text Size Email Print Share Hepatitis Page Content Article Body Hepatitis means “inflammation of ... it has been associated with drinking contaminated water. Hepatitis Viruses Type Transmission Prognosis A Fecal-oral (stool ...

  11. Differential regulation of hepatic enzymes by polycyclic aromatic hydrocarbons and glucocorticoids

    SciTech Connect

    Smith, J.A.; Linder, M.W.; Fernandez, D.; Prough, R.A. )

    1991-03-15

    A putative glucocorticoid (GC) response element has been identified within the first intron of the P450IA1 gene and is apparently necessary for GC-dependent potentiation of polycyclic aromatic hydrocarbon (PAH) induction of P450IA1. In cultured rat hepatocytes, the synthetic GC, dexamethasone (DEX), potentiated PAH induction of both P450IA1 and glutathione S-transferase protein and mRNA. However, DEX caused a small decrease in PAH-dependent induction of NAD(P)H:quinone oxidoreductase (QOR) subunit protein and mRNA in culture. The potentiation of 3-methylcholanthrene (MC) dependent induction of hepatic P450IA1, GST and QOR by low doses of DEX was evaluated in neonatal and adult rats. In neonates, MC induction was potentiated 2-, 1.5-, and 1.4-fold for P450IA1, GST, and QOR activities, respectively, by DEX. However, in adult rats, DEX potentiated MC induction of P450IA1 activity, but repressed MC induction of GST and QOR. Western immunoanalysis and Northern analysis indicated that the changes in these activities were associated with parallel changes in the levels of immunoreactive proteins and mRNA. Glucocorticoids may have an age-dependent influence on the induction of hepatic enzymes by PAH possibly involving other regulatory factors, in addition to Ah and GC receptors.

  12. The role of human carboxylesterases in drug metabolism: have we overlooked their importance?

    PubMed

    Laizure, S Casey; Herring, Vanessa; Hu, Zheyi; Witbrodt, Kevin; Parker, Robert B

    2013-02-01

    Carboxylesterases are a multigene family of mammalian enzymes widely distributed throughout the body that catalyze the hydrolysis of esters, amides, thioesters, and carbamates. In humans, two carboxylesterases, hCE1 and hCE2, are important mediators of drug metabolism. Both are expressed in the liver, but hCE1 greatly exceeds hCE2. In the intestine, only hCE2 is present and highly expressed. The most common drug substrates of these enzymes are ester prodrugs specifically designed to enhance oral bioavailability by hydrolysis to the active carboxylic acid after absorption from the gastrointestinal tract. Carboxylesterases also play an important role in the hydrolysis of some drugs to inactive metabolites. It has been widely believed that drugs undergoing hydrolysis by hCE1 and hCE2 are not subject to clinically significant alterations in their disposition, but evidence exists that genetic polymorphisms, drug-drug interactions, drug-disease interactions and other factors are important determinants of the variability in the therapeutic response to carboxylesterase-substrate drugs. The implications for drug therapy are far-reaching, as substrate drugs include numerous examples from widely prescribed therapeutic classes. Representative drugs include angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, antiplatelet drugs, statins, antivirals, and central nervous system agents. As research interest increases in the carboxylesterases, evidence is accumulating of their important role in drug metabolism and, therefore, the outcomes of pharmacotherapy.

  13. Time-dependent inhibition of human drug metabolizing cytochromes P450 by tricyclic antidepressants

    PubMed Central

    Polasek, Thomas M; Miners, John O

    2008-01-01

    AIMS To investigate time-dependent inhibition (TDI) of human drug metabolizing CYP enzymes by tricyclic antidepressants (TCAs). METHODS CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A/CYP3A4 activities were investigated following co- and preincubation with TCAs using human liver microsomes (HLM) and human recombinant CYP proteins (expressed in Escherichia coli) as the enzyme sources. A two-step incubation method was employed to examine the in vitro mechanism-based inactivation (MBI) criteria. Potential metabolite–intermediate complex (MIC) formation was studied by spectral analysis. RESULTS TCAs generally exhibited significant TDI of recombinant CYP1A2, CYP2C19 and CYP2D6 (>10% positive inhibition differences between co- and preincubation conditions). TDI of recombinant CYP2C9 was minor (<10%), and was minor or absent in experiments utilizing recombinant CYP3A4 or HLM as the enzyme sources. Where observed, TDI of recombinant CYP occurred via alkylamine MIC formation, but evidence to support similar behaviour in HLM was limited. Indeed, only secondary amine TCAs reduced the apparent P450 content of HLM (3–6%) consistent with complexation. As a representative TCA, nortriptyline fulfilled the in vitro MBI criteria using recombinant CYP2C19 and CYP3A4 (KI and kinact values of 4 µm and 0.19 min−1, and 70 µm and 0.06 min−1), but not with the human liver microsomal enzymes. CONCLUSIONS TCAs appear to have minimal potential for MBI of human liver microsomal CYP enzymes involved in drug metabolism. HLM and recombinant CYP (expressed in E. coli) are not equivalent enzyme sources for evaluating the TDI associated with some drugs. WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT Much of the literature evidence for mechanism-based inactivation (MBI) of CYP by tricyclic antidepressants is limited to studies in rat liver microsomes. One report from this laboratory characterized MBI of human recombinant CYP2C8 by nortriptyline. WHAT THIS STUDY ADDS Tricyclic antidepressants form

  14. Prevalence of poor and rapid metabolizers of drugs metabolized by CYP2B6 in North Indian population residing in Indian national capital territory.

    PubMed

    Varshney, Ekta; Saha, Nilanjan; Tandon, Monika; Shrivastava, Vikesh; Ali, Shakir

    2012-01-01

    Identification of poor and rapid metabolizers for the category of drugs metabolized by cytochrome P450 2B6 (CYP2B6) is important for understanding the differences in clinical responses of drugs metabolized by this enzyme. This study reports the prevalence of poor and rapid metabolizers in North Indian population residing in the National Capital Territory. The prevalence of poor and rapid metabolizers was determined in the target population for the category of drugs metabolized by CYP2B6 by measuring plasma bupropion, a drug metabolized by CYP2B6, and its metabolite. Bupropion (75 mg) was administered to 107 volunteers, and the drug (bupropion) and its metabolite (hydroxybupropion) were determined simultaneously by LCMS/MS in the plasma. CYP2B6 activity was measured as hydroxybupropion/bupropion ratio, and volunteers were categorized as rapid or poor metabolizers on the basis of cutoff value of log (hydroxybupropion/bupropion). Significant differences were observed between the mean metabolite/drug ratio of rapid metabolizers (Mean = 0.59) and poor metabolizers (Mean = 0.26) with p<0.0001. Results indicate that 20.56% individuals in the target population were poor metabolizers for the category of drugs metabolized by CYP2B6. Cutoff value defined in this study can be used as a tool for evaluating the status of CYP2B6 using bupropion as a probe drug. The baseline information would be clinically useful before administering the drugs metabolized by this isoform.

  15. DrugBank 4.0: shedding new light on drug metabolism

    PubMed Central

    Law, Vivian; Knox, Craig; Djoumbou, Yannick; Jewison, Tim; Guo, An Chi; Liu, Yifeng; Maciejewski, Adam; Arndt, David; Wilson, Michael; Neveu, Vanessa; Tang, Alexandra; Gabriel, Geraldine; Ly, Carol; Adamjee, Sakina; Dame, Zerihun T.; Han, Beomsoo; Zhou, You; Wishart, David S.

    2014-01-01

    DrugBank (http://www.drugbank.ca) is a comprehensive online database containing extensive biochemical and pharmacological information about drugs, their mechanisms and their targets. Since it was first described in 2006, DrugBank has rapidly evolved, both in response to user requests and in response to changing trends in drug research and development. Previous versions of DrugBank have been widely used to facilitate drug and in silico drug target discovery. The latest update, DrugBank 4.0, has been further expanded to contain data on drug metabolism, absorption, distribution, metabolism, excretion and toxicity (ADMET) and other kinds of quantitative structure activity relationships (QSAR) information. These enhancements are intended to facilitate research in xenobiotic metabolism (both prediction and characterization), pharmacokinetics, pharmacodynamics and drug design/discovery. For this release, >1200 drug metabolites (including their structures, names, activity, abundance and other detailed data) have been added along with >1300 drug metabolism reactions (including metabolizing enzymes and reaction types) and dozens of drug metabolism pathways. Another 30 predicted or measured ADMET parameters have been added to each DrugCard, bringing the average number of quantitative ADMET values for Food and Drug Administration-approved drugs close to 40. Referential nuclear magnetic resonance and MS spectra have been added for almost 400 drugs as well as spectral and mass matching tools to facilitate compound identification. This expanded collection of drug information is complemented by a number of new or improved search tools, including one that provides a simple analyses of drug–target, –enzyme and –transporter associations to provide insight on drug–drug interactions. PMID:24203711

  16. Urinary D-glucaric acid and serum hepatic enzyme levels in chronic alcoholics.

    PubMed

    Tutor, J C; Alvarez-Prechous, A; Bernabeu, F; Pardiñas, M C; Paz, J M; Lareu, V

    1988-06-01

    Urinary D-glucaric acid (DGA) and the activities of gamma-glutamyl transferase (GGT) and other hepatic enzymes in serum were determined in 33 noncirrhotic male alcoholics who had continued to consume alcohol until at least 24 h prior to the taking of samples. DGA excretion was significantly greater in them than in a group of 30 healthy controls (p less than 0.001), exceeding the upper reference level in 38% of the alcoholic cases (as compared with 88% for GGT). In the alcoholic patients, there was highly significant correlation between urinary DGA and serum GGT (r = 0.613, p less than 0.001), suggesting that in both cases the increased levels are due to enzyme induction. None of the biochemical variables studied were significantly correlated with estimated daily alcohol consumption. Urinary DGA levels fell off rapidly with abstinence, and in 31 alcoholic patients who had consumed no alcohol for 5 days, there was no statistically significant correlation between DGA excretion and serum GGT (r = 0.158, p congruent to 0.4).

  17. Pregnane X receptor regulates drug metabolism and transport in the vasculature and protects from oxidative stress

    PubMed Central

    Swales, Karen E.; Moore, Rick; Truss, Nicola J.; Tucker, Arthur; Warner, Timothy D.; Negishi, Masahiko; Bishop-Bailey, David

    2012-01-01

    Aims Circulating endogenous, dietary, and foreign chemicals can contribute to vascular dysfunction. The mechanism by which the vasculature protects itself from these chemicals is unknown. This study investigates whether the pregnane X receptor (PXR), the major transcriptional regulator of hepatic drug metabolism and transport that responds to such xenobiotics, mediates vascular protection by co-ordinating a defence gene programme in the vasculature. Methods and results PXR was detected in primary human and rat aortic endothelial and smooth muscle cells (SMC) and blood vessels including the human and rat aorta. Metabolic PXR target genes cytochrome P450 3A, 2B, 2C, and glutathione S-transferase mRNA and activity were induced by PXR ligands in rodent and human vascular cells and absent in the aortas from PXR-null mice stimulated in vivo or in rat aortic SMC expressing dominant-negative PXR. Activation of aortic PXR by classical agonists had several protective effects: increased xenobiotic metabolism demonstrated by bioactivation of the pro-drug clopidogrel, which reduced adenosine diphosphate-induced platelet aggregation; increased expression of multidrug resistance protein 1, mediating chemical efflux from the vasculature; and protection from reactive oxygen species-mediated cell death. Conclusion PXR co-ordinately up-regulates drug metabolism, transport, and antioxidant genes to protect the vasculature from endogenous and exogenous insults, thus representing a novel gatekeeper for vascular defence. PMID:22166712

  18. Effects of Chinese, Japanese and Western tea on hepatic P450 enzyme activities in rats.

    PubMed

    Niwattisaiwong, N; Luo, X X; Coville, P F; Wanwimolruk, S

    2004-01-01

    Previous studies have reported that green tea effectively protects against cancers caused by various dietary carcinogens. As P450 enzymes are the major system responsible for the metabolism of many carcinogens, we hypothesise that tea consumption may alter the catalytic activities of P450 enzymes. We conducted this study to screen the effects of four different teas on the activities of P450 enzymes. Tea solutions (2.5%) were prepared by adding boiling water to tea leaves and filtering. Female Wistar rats were divided into five groups (n = 4 each); each had free access to tea solutions while the control group was supplied with water for 4 weeks. Animals were sacrificed and livers were removed for preparation of microsomes. Enzyme activities were determined by incubation of liver microsomes with the appropriate CYP substrate. The activity of CYP1A1 in livers from rats receiving Oolong (Chinese) tea (185 +/- 63 pmol/mg/min), Japanese green tea (197 +/- 22 pmol/mg/min) and Earl Grey tea (228 +/- 40 pmol/mg/min) was significantly higher (p < 0.05) than in the control group (94 +/- 34 pmol/mg/min), whereas no change was observed in the activity of CYP1A2 in any of tested animals. The hepatic activity of CYP2D6 was greater only in rats drinking Earl Grey tea compared to the controls (235 +/- 37 vs 161 +/- 41 pmol/mg/min, p < 0.05). There were also significant increases (p < 0.05) in the activity of CYP3A in livers of animals given Oolong tea (653 +/- 174 vs 382 +/- 114 pmol/mg/min) and Earl Grey tea (751 +/- 202 pmol/mg/min), while Jasmine and Japanese green tea had no significant effect. These results indicate that not all types of tea cause alterations in liver CYP enzymes as some elevated activities and some did not. Further studies are needed to determine whether there is a relationship between the effect of tea on CYP activities and anti-carcinogenesis.

  19. Role of Cytochrome P450 Monooxygenase in Carcinogen and Chemotherapeutic Drug Metabolism.

    PubMed

    Wahlang, B; Falkner, K Cameron; Cave, Matt C; Prough, Russell A

    2015-01-01

    The purpose of this chapter is to provide insight into which human cytochromes P450 (CYPs) may be involved in metabolism of chemical carcinogens and anticancer drugs. A historical overview of this field and the development of literature using relevant animal models and expressed human CYPs have provided information about which specific CYPs may be involved in carcinogen metabolism. Definition of the biochemical properties of CYP activity came from several groups who studied the reaction stoichiometry of butter yellow and benzo[α]pyrene, including their role in induction of these enzyme systems. This chapter will list as much as is known about the human CYPs involved in carcinogen and anticancer drug metabolism, as well as summarize studies with rodent CYPs. A review of three major classes of anticancer drugs and their metabolism in humans is covered for cyclophosphamide, procarbazine, and anthracycline antibiotics, cancer chemotherapeutic compounds extensively metabolized by CYPs. The emerging information about human CYP gene polymorphisms as well as other enzymes involved in foreign compound metabolism provides considerable information about how these genetic variants affect carcinogen and anticancer drug metabolism. With information available from individual's genomic sequences, consideration of populations who may be at risk due to environmental exposure to carcinogens or how to optimize their cancer therapy regimens to enhance efficacy of the anticancer drugs appears to be an important field of study to benefit individuals in the future.

  20. Expression profile of hepatic genes in cynomolgus macaques bred in Cambodia, China, and Indonesia: implications for cytochrome P450 genes.

    PubMed

    Ise, Ryota; Nakanishi, Yasuharu; Kohara, Sakae; Yamashita, Hiroyuki; Yoshikawa, Tsuyoshi; Iwasaki, Kazuhide; Nagata, Ryoichi; Fukuzaki, Koichiro; Utoh, Masahiro; Nakamura, Chika; Yamazaki, Hiroshi; Uno, Yasuhiro

    2012-01-01

    Cynomolgus macaques, frequently used in drug metabolism studies, are bred mainly in the countries of Asia; however, comparative studies of drug metabolism between cynomolgus macaques bred in these countries have not been conducted. In this study, hepatic gene expression profiles of cynomolgus macaques bred in Cambodia (mfCAM), China (mfCHN), and Indonesia (mfIDN) were analyzed. Microarray analysis revealed that expression of most hepatic genes, including drug-metabolizing enzyme genes, was not substantially different between mfCAM, mfCHN, and mfIDN; only 1.1% and 3.0% of all the gene probes detected differential expression (>2.5-fold) in mfCAM compared with mfCHN and mfIDN, respectively. Quantitative polymerase chain reaction showed that the expression levels of 14 cytochromes P450 (P450s) important for drug metabolism did not differ (>2.5-fold) in mfCAM, mfCHN, and mfIDN, validating the microarray data. In contrast, expression of CYP2B6 and CYP3A4 differed (>2.5-fold, p < 0.05) between cynomolgus (mfCAM, mfCHN, or mfIDN) and rhesus macaques, indicating greater differences in expression of P450 genes between the two lineages. Moreover, metabolic activities measured using 14 P450 substrates did not differ substantially (<1.5-fold) between mfCAM and mfCHN. These results suggest that gene expression profiles, including drug-metabolizing enzyme genes such as P450 genes, are similar in mfCAM, mfCHN, and mfIDN.

  1. Short communication: Regulation of hepatic gluconeogenic enzymes by dietary glycerol in transition dairy cows.

    PubMed

    White, H M; Carvalho, E R; Koser, S L; Schmelz-Roberts, N S; Pezzanite, L M; Slabaugh, A C; Doane, P H; Donkin, S S

    2016-01-01

    Nutritional status and glucose precursors are known regulators of gluconeogenic gene expression. Glycerol can replace corn in diets fed to dairy cows and use of glycerol is linked to increased rumen propionate production. The effect of dietary glycerol on the regulation of gluconeogenic enzymes is unknown. The objective of this study was to examine the effect of glycerol on expression of pyruvate carboxylase (PC), cytosolic and mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-C and PEPCK-M), and glucose-6-phosphatase. Twenty-six multiparous Holstein cows were fed either a control diet or a diet where high-moisture corn was replaced by glycerol from -28 through +56 d relative to calving (DRTC). Liver tissue was collected via percutaneous liver biopsy at -28, -14, +1, +14, +28, and +56 DRTC for RNA analysis. Expression of PC mRNA increased 6-fold at +1 and 4-fold at +14 DRTC relative to precalving levels. Dietary glycerol did not alter expression of PC mRNA expression. Expression of PEPCK-C increased 2.5-fold at +14 and 3-fold at +28 DRTC compared with +1 DRTC. Overall, dietary glycerol increased PEPCK-C expression compared with that of cows fed control diets. The ratio of PC to PEPCK-C was increased 6.3-fold at +1 DRTC compared with precalving and tended to be decreased in cows fed glycerol. We detected no effect of diet or DRTC on PEPCK-M or glucose-6-phosphatase mRNA, and there were no interactions of dietary treatment and DRTC for any transcript measured. Substituting corn with glycerol increased the expression of PEPCK-C mRNA during transition to lactation and suggests that dietary energy source alters hepatic expression. The observed increase in PEPCK-C expression with glycerol feeding may indicate regulation of hepatic gene expression by changes in rumen propionate production.

  2. Evaluation of a novel chemiluminescent microplate enzyme immunoassay for hepatitis B surface antigen detection.

    PubMed

    Yang, Lin; Song, Liu-Wei; Fang, Lin-Lin; Wu, Yong; Ge, Sheng-Xiang; Li, Hui; Yuan, Quan; Zhang, Jun; Xia, Ning-Shao

    2016-02-01

    Hepatitis B virus surface antigen (HBsAg) is an important biomarker used in the diagnosis of hepatitis B virus (HBV) infection, but false-negative results are still reported in the detection of HBsAg using commercial assays. In this study, we evaluated the qualitative properties of a novel HBsAg chemiluminescence enzyme immunoassay (CLEIA) assay--WTultra. WHO standard sample dilution series and samples from low-level HBsAg carriers (<1 ng/mL) were used to evaluate the sensitivity of the WTultra assay. Boston Biomedica, Inc. (BBI) hepatitis B seroconversion panels were used to assess the ability of the WTultra assay to detect the window period. In addition, dilution series of 22 serum samples with different genotypes, serotypes and HBsAg mutations were used to assess the WTultra assay, and these were compared with other commercial assays. The lower detection limit of the WTultra assay was 0.012 IU/mL, and it showed a high sensitivity (97.52%, 95% CI, 94.95-99.00) in the detection of 282 low-level HBsAg carriers (<1 ng/mL). In samples with various HBV genotypes, serotypes and HBsAg mutations, the WTultra assay yielded 117 positive results in 132 samples, which was significantly higher than the results with the other four commercial assays (89, 83, 65 and 45, respectively, p<0.01). In the assays of mutant strains, the WTultra assay detected 82 positive results in 90 samples, which was significantly better than the results for the Hepanostika HBsAg Ultra (58 positive) and Architect (55 positive) (p<0.01) assays, which in turn were significantly better than the Murex V.3 (41 positive, p=0.026) and AxSYM V2 (29 positive, p<0.01) assays. However, in the detection of 42 samples of wild-type strains with various genotypes and serotypes, no significant differences were observed among the WTultra (35 positive), Architect (28 positive) and Hepanostika HBsAg Ultra (31 positive) assays. However, the WTultra assay detected significantly more samples than the Murex V.3 (24

  3. The cytochrome P450 superfamily: biochemistry, evolution and drug metabolism in humans.

    PubMed

    Danielson, P B

    2002-12-01

    Cytochrome p450s comprise a superfamily of heme-thiolate proteins named for the spectral absorbance peak of their carbon-monoxide-bound species at 450 nm. Having been found in every class of organism, including Archaea, the p450 superfamily is believed to have originated from an ancestral gene that existed over 3 billion years ago. Repeated gene duplications have subsequently given rise to one of the largest of multigene families. These enzymes are notable both for the diversity of reactions that they catalyze and the range of chemically dissimilar substrates upon which they act. Cytochrome p450s support the oxidative, peroxidative and reductive metabolism of such endogenous and xenobiotic substrates as environmental pollutants, agrochemicals, plant allelochemicals, steroids, prostaglandins and fatty acids. In humans, cytochrome p450s are best know for their central role in phase I drug metabolism where they are of critical importance to two of the most significant problems in clinical pharmacology: drug interactions and interindividual variability in drug metabolism. Recent advances in our understanding of cytochrome p450-mediated drug metabolism have been accelerated as a result of an increasing emphasis on functional genomic approaches to p450 research. While human cytochrome p450 databases have swelled with a flood of new human sequence variants, however, the functional characterization of the corresponding gene products has not kept pace. In response researchers have begun to apply the tools of proteomics as well as homology-based and ab initio modeling to salient questions of cytochrome p450 structure/function. This review examines the latest advances in our understanding of human cytochrome p450s.

  4. Perifusion of co-cultured hepatocytes: optimization of studies on drug metabolism and cytotoxicity in vitro.

    PubMed

    Gebhardt, R; Wegner, H; Alber, J

    1996-04-01

    The combination of co-cultivation of hepatocytes and epithelial cell lines with a newly developed perifusion system was used for in vitro studies on drug metabolism and cytotoxicity. This approach improved the viability and enhanced the induction of the biotransforming capacity of the hepatocytes. As demonstrated for the induction of 7-ethoxyresorufin O-deethylase activity by 3-methylcholanthrene or benzanthracene, co-cultured hepatocytes in the perifusion system responded more sensitively to these inducers than without perifusion, most likely owing to stable (steady-state) concentrations of the inducers under the former conditions and rapidly declining concentrations under the latter conditions. The perifusion approach rendered it possible to determine the kinetics of drug metabolism during single or sequential incubations. After induction with 3-methylcholanthrene and phenobarbital, phase I metabolism of lonazolac to the monohydroxylated product in perifused co-cultures closely (87%) approached the values reported for the in vivo production, whereas in stationary co-cultures only 52% could be reached. Likewise, cytotoxic effects could be detected more precisely in the perifused co-cultures. If cells were pretreated with 0.2 mmol/L galactosamine for 3 h, perifusion with increasing concentrations of menadione differentially killed epithelial RL-ET-14 cells and hepatocytes at low and high concentrations, respectively, while in stationary co-cultures no differential effect was observed and only the higher concentrations were cytotoxic for both cells. Prevention by incubation with S-adenosylmethionine of menadione cytotoxicity up to a menadione concentration of 250 micromol/L was seen only in the perifused co-cultures, whereas in stationary cultures only a slight shift of the cytotoxic concentration exerting 50% cell damage to higher values was noted. These results demonstrate the versatile application of perifused co-cultures for studies on drug metabolism including

  5. Hepatic Enzyme Decline after Pediatric Blunt Trauma: A Tool for Timing Child Abuse?

    ERIC Educational Resources Information Center

    Baxter, Amy L.; Lindberg, Daniel M.; Burke, Bonnie L.; Shults, Justine; Holmes, James F.

    2008-01-01

    Objectives: Previous research in adult patients with blunt hepatic injuries has suggested a pattern of serum hepatic transaminase concentration decline. Evaluating this decline after pediatric blunt hepatic trauma could establish parameters for estimating the time of inflicted injuries. Deviation from a consistent transaminase resolution pattern…

  6. Regulation of hepatic transporters by xenobiotic receptors.

    PubMed

    Klaassen, C D; Slitt, A L

    2005-08-01

    Chemicals that increase expression of phase-I and -II biotransformation enzymes in liver, as well as enhance hepatic uptake and biliary excretion are often referred to as microsomal enzyme inducers (MEIs). Early studies suggested that drug metabolism might be coordinately regulated along with drug efflux from hepatocytes as a means for the liver to rid itself of foreign chemicals. Since then, the identification and characterization of nuclear receptors (NRs) has aided in understanding of how various MEIs enhance xeniobiotic uptake, biotransformation, and excretion. In addition, the NRs by which several classes of MEIs induce phase-I and -II drug metabolizing enzymes have been elucidated (i.e. AHR, CAR, PXR, PPARalpha, Nrf2). Several transporter families which mediate uptake of chemicals into liver and excretion of chemicals from liver into blood and/or bile have been cloned and identified. In general, the organic anion transporting polypeptide family (Oatps) along with Organic cation transporter 1 (Oct1) and Organic anion transporter 2 mediate uptake of a large number of xenobiotics from blood into liver. Conversely, Multidrug resistance proteins (Mdrs), Multidrug resistance-associated proteins (Mrps), and Breast cancer resistance protein (Bcrp) mediate efflux of xenobiotics from liver into bile or blood. Recent studies have demonstrated that MEIs increase expression of various Oatps, Mrps, and Mdrs in liver, and some occur via activation of nuclear receptors.

  7. Schisandra Chinensis Baillon regulates the gene expression of phase II antioxidant/detoxifying enzymes in hepatic damage induced rats

    PubMed Central

    Jang, Han I; Do, Gyeong-Min; Lee, Hye Min; Ok, Hyang Mok; Shin, Jae-Ho

    2014-01-01

    BACKGROUND/OBJECTIVES This study investigated the antioxidant activities and hepatoprotective effects of Schisandra chinensis Baillon extract (SCE) against tert-butyl hydroperoxide (t-BHP)-induced oxidative hepatic damage in rats. MATERIALS/METHODS Sprague-Dawley (SD) rats were pretreated with SCE (300, 600, and 1,200 mg/kg BW) or saline once daily for 14 consecutive days. On day 14, each animal, except those belonging to the normal control group, were injected with t-BHP (0.8 mmol/kg BW/i.p.), and all of the rats were sacrificed 16 h after t-BHP injection. RESULTS Although no significant differences in AST and ALT levels were observed among the TC and SCE groups, the high-dose SCE group showed a decreasing tendency compared to the TC group. However, erythrocyte SOD activity showed a significant increase in the low-dose SCE group compared with the TC group. On the other hand, no significant differences in hepatic total glutathione (GSH) level, glutathione reductase (GR), and glutathione peroxidase (GSH-Px) activities were observed among the TC and SCE groups. Hepatic histopathological evaluation revealed that pretreatment with SCE resulted in reduced t-BHP-induced incidence of lesions, such as neutrophil infiltration, swelling of liver cells, and necrosis. In particular, treatment with a high dose of SCE resulted in induction of phase II antioxidant/detoxifying enzyme expression, such as glutathione S-transferase (GST) and glutamate-cysteine ligase catalytic subunit (GCLC). CONCLUSIONS Based on these results, we conclude that SCE exerts protective effects against t-BHP induced oxidative hepatic damage through the reduction of neutrophil infiltration, swelling of liver cells, and necrosis. In addition, SCE regulates the gene expression of phase II antioxidant/detoxifying enzymes independent of hepatic antioxidant enzyme activity. PMID:24944771

  8. Electrochemistry-mass spectrometry in drug metabolism and protein research.

    PubMed

    Permentier, Hjalmar P; Bruins, Andries P; Bischoff, Rainer

    2008-01-01

    The combination of electrochemistry coupled on-line to mass spectrometry (EC-MS) forms a powerful analytical technique with unique applications in the fields of drug metabolism and proteomics. In this review the latest developments are surveyed from both instrumental and application perspectives. The limitations and solutions for coupling an electrochemical system to a mass spectrometer are discussed. The electrochemical mimicking of drug metabolism, specifically by Cytochrome P450, is high-lighted as an application with high biomedical relevance. The EC-MS analysis of proteins also has promising new applications for both proteomics research and biomarker discovery. EC-MS has furthermore advantages for improved analyte detection with mass spectrometry, both for small molecules and large biomolecules. Finally, potential future directions of development of the technique are briefly discussed.

  9. Effects of Angiotensin Converting Enzyme Inhibitors on Liver Fibrosis in HIV and Hepatitis C Coinfection.

    PubMed

    Reese, Lindsey J; Tider, Diane S; Stivala, Alicia C; Fishbein, Dawn A

    2012-01-01

    Background. Liver fibrosis is accelerated in HIV and hepatitis C coinfection, mediated by profibrotic effects of angiotensin. The objective of this study was to determine if angiotensin converting enzyme inhibitors (ACE-Is) attenuate liver fibrosis in coinfection. Methods. A retrospective review of 156 coinfected subjects was conducted to analyze the association between exposure to ACE-Is and liver fibrosis. Noninvasive indices of liver fibrosis (APRI, FIB-4, Forns indices) were compared between subjects who had taken ACE-Is and controls who had not taken them. Linear regression was used to evaluate ACE-I use as an independent predictor of fibrosis. Results. Subjects taking ACE-Is for three years were no different than controls on the APRI and the FIB-4 but had significantly higher scores than controls on the Forns index, indicating more advanced fibrosis. The use of ACE-Is for three years remained independently associated with an elevated Forns score when adjusted for age, race, and HIV viral load (P < 0.001). There were significant associations between all of the indices and significant fibrosis, as determined clinically and radiologically. Conclusions. There was not a protective association between angiotensin inhibition and liver fibrosis in coinfection. These noninvasive indices may be useful for ruling out significant fibrosis in coinfection.

  10. The effects of fenvalerate on hepatic and cerebral xenobiotic metabolizing enzymes in selenium and/or iodine deficient rats

    PubMed Central

    Caglayan, Aydan; Kocer-Gumusel, Belma; Erkekoglu, Pinar; Hincal, Filiz

    2016-01-01

    Objective(s): Particularly in developing countries, selenium and/or iodine deficiencies are encountered and use of pesticides in agriculture are not well-controlled. Fenvalerate is a pyrethroid insectide used in agriculture and has applications against a wide range of pests. This study was designed to evaluate the effects of fenvalerate on hepatic and cerebral xenobiotic metabolizing enzyme activities in the presence of iodine and/or selenium deficiency on a rat model. Materials and Methods: Iodine and/or selenium deficiency was induced by feeding three-week-old Wistar rats with a diet containing <0.005 mg selenium kg-1, and/or administering 1% sodium perchlorate in drinking water for 7 weeks. Test groups received fenvalerate (100 mg kg-1 BW IP) for the last 7 days. Hepatic and cerebral microsomal aniline hydroxylase (CYP2E1) and cytosolic glutathione S-transferase (GST) activities were determined. Besides, hepatic NADPH-cytochrome P450 reductase (P450R), ethoxyresorufin O-deethylase (EROD, CYP1A1/1A2) and penthoxyresorufin O-depenthylase (PROD, CYP2B1/2B2), activities were also measured. Results: Fenvalerate had a general inductive effect on the hepatic and cerebral xenobiotic metabolizing enzyme activities. Moreover, enzyme activities were also altered by iodine and/or selenium deficiency, but the effects seemed to be enzyme- and tissue-specific. Conclusion: The inductive effect of fenvalerate, particularly in high dose exposures, may change the metabolism of several xenobiotics, including drugs, as well as endogenous substrates. The effects may vary depending on the selenium and/or iodine status of individual. PMID:27872699

  11. Multicentric evaluation of new commercial enzyme immunoassays for the detection of immunoglobulin M and total antibodies against hepatitis A virus.

    PubMed

    Arcangeletti, M C; Dussaix, E; Ferraglia, F; Roque-Afonso, A M; Graube, A; Chezzi, C

    2011-08-01

    A multicentric clinical study was conducted on representative sera from 1,738 European and U.S. subjects for the evaluation of new anti-hepatitis A virus enzyme immunoassays from Bio-Rad Laboratories. Comparison with reference DiaSorin S.p.A. tests confirmed the good performance of Bio-Rad assays (99.85% and 99.47% overall agreement in detecting total antibodies and IgM, respectively).

  12. Multicentric Evaluation of New Commercial Enzyme Immunoassays for the Detection of Immunoglobulin M and Total Antibodies against Hepatitis A Virus▿

    PubMed Central

    Arcangeletti, M. C.; Dussaix, E.; Ferraglia, F.; Roque-Afonso, A. M.; Graube, A.; Chezzi, C.

    2011-01-01

    A multicentric clinical study was conducted on representative sera from 1,738 European and U.S. subjects for the evaluation of new anti-hepatitis A virus enzyme immunoassays from Bio-Rad Laboratories. Comparison with reference DiaSorin S.p.A. tests confirmed the good performance of Bio-Rad assays (99.85% and 99.47% overall agreement in detecting total antibodies and IgM, respectively). PMID:21653739

  13. Di2-ethylhexyl phthalate disrupts thyroid hormone homeostasis through activating the Ras/Akt/TRHr pathway and inducing hepatic enzymes

    PubMed Central

    Ye, Hanfeng; Ha, Mei; Yang, Min; Yue, Ping; Xie, Zhengyuan; Liu, Changjiang

    2017-01-01

    Di(2-ethylhexyl) phthalate (DEHP), as a widespread environmental pollutant and an endocrine disruptor, can disturb the homeostasis of thyroid hormones (THs). In order to elucidate roles of the MAPK and PI3K/Akt pathways and hepatic enzymes in thyroid-disrupting effects of DEHP, Sprague-Dawley rats were dosed with DEHP by gavage for 30 consecutive days; Nthy-ori 3-1 cells were treated with DEHP with NAC, k-Ras siRNA or inhibitors (U0126 and wortmannin). Results showed that DEHP led to histopathologic changes in rat thyroid and liver, such as the decrease in thyroid follicular cavity diameter, hepatocyte edema. Triiodothyronine (T3), thyroxine (T4) and thyrotropin releasing hormone (TRH) were reduced. DEHP caused ROS production, oxidative stress and k-Ras upregulation, thereby activating the ERK and Akt pathways in vivo and in vitro. Moreover, TRH receptor (TRHr) level was elevated after the activation of the Akt pathway and was downregulated after the inhibition of the Akt pathway. However, TRHr was not modulated by the ERK pathway. Additionally, hepatic enzymes, including Ugt1a1, CYP2b1, Sult1e1, and Sult2b1, were significantly induced after DEHP exposure. Taken together, DEHP can perturb TH homeostasis and reduce TH levels. The activated Ras/Akt/TRHr pathway and induced hepatic enzymes play vital roles in thyroid-disrupting effects of DEHP. PMID:28065941

  14. Di2-ethylhexyl phthalate disrupts thyroid hormone homeostasis through activating the Ras/Akt/TRHr pathway and inducing hepatic enzymes.

    PubMed

    Ye, Hanfeng; Ha, Mei; Yang, Min; Yue, Ping; Xie, Zhengyuan; Liu, Changjiang

    2017-01-09

    Di(2-ethylhexyl) phthalate (DEHP), as a widespread environmental pollutant and an endocrine disruptor, can disturb the homeostasis of thyroid hormones (THs). In order to elucidate roles of the MAPK and PI3K/Akt pathways and hepatic enzymes in thyroid-disrupting effects of DEHP, Sprague-Dawley rats were dosed with DEHP by gavage for 30 consecutive days; Nthy-ori 3-1 cells were treated with DEHP with NAC, k-Ras siRNA or inhibitors (U0126 and wortmannin). Results showed that DEHP led to histopathologic changes in rat thyroid and liver, such as the decrease in thyroid follicular cavity diameter, hepatocyte edema. Triiodothyronine (T3), thyroxine (T4) and thyrotropin releasing hormone (TRH) were reduced. DEHP caused ROS production, oxidative stress and k-Ras upregulation, thereby activating the ERK and Akt pathways in vivo and in vitro. Moreover, TRH receptor (TRHr) level was elevated after the activation of the Akt pathway and was downregulated after the inhibition of the Akt pathway. However, TRHr was not modulated by the ERK pathway. Additionally, hepatic enzymes, including Ugt1a1, CYP2b1, Sult1e1, and Sult2b1, were significantly induced after DEHP exposure. Taken together, DEHP can perturb TH homeostasis and reduce TH levels. The activated Ras/Akt/TRHr pathway and induced hepatic enzymes play vital roles in thyroid-disrupting effects of DEHP.

  15. Drug metabolism and pharmacogenetics: the British contribution to fields of international significance

    PubMed Central

    Caldwell, John

    2006-01-01

    The branch of pharmacology we now call ‘drug metabolism', the consideration of the enzymes and procesess determining the disposition of drugs in the body, emerged in the 1840s on the continent of Europe, but British science made little or no contribution until the 1920s. From this point on, the development of the field through the 20th century was shaped to a very significant extent by a series of influential British workers, whose contributions were of global significance and who can now be seen as fathers of the subject. Since the 1950s, and gaining pace inexorably from the 1970s, the significance of drug metabolism to human therapeutics has been greatly added to by the emergence of pharmacogenetics, clinically important hereditary variation in response to drugs, which underpins the current emphasis on personalised medicine. This review examines the British contributions to both these fields through the lives of seven key contributors and attempts to place their work both in the context of its time and its lasting influence. PMID:16402125

  16. Comparative effects of medetomidine enantiomers on in vitro and in vivo microsomal drug metabolism.

    PubMed

    Pelkonen, O; Puurunen, J; Arvela, P; Lammintausta, R

    1991-09-01

    The effects of dexmedetomidine, a selective alpha 2-adrenoceptor agonist, and its levo enantiomer (MPV-1441), on in vitro microsomal P450-dependent drug-metabolizing activities as well as on in vivo aminopyrine elimination and hexobarbital sleeping time were studied. Both enantiomers inhibited the oxidative metabolism of several model substrates and testosterone in rat liver microsomal incubations. Microsomal activities derived from control animals or rats pretreated with phenobarbital were more sensitive to inhibitory effects of dexmedetomidine than those from rats treated with 3-methylcholanthrene. Enzyme activities in human liver microsomes were also inhibited by dexmedetomidine. Retardation of the elimination of aminopyrine was dose-dependent; elimination was marginally retarded with doses up to 100 micrograms/kg (from 17 to 23 min.; both enantiomers). Higher doses of the levo enantiomer prolonged aminopyrine half-life to 78 (1 mg/kg) and 162 min. (10 mg/kg). The hexobarbital sleeping time was prolonged by the dose of 1 mg/kg of the levo enantiomer (128 min. versus 20 min. in controls), while the dose of 0.1 mg/kg had no effect (23 versus 20 min.). These studies indicate that both enantiomers of medetomidine are inhibitors of microsomal drug metabolism in vitro, but significant effects on aminopyrine elimination or hexobarbital sleeping time are apparent only at doses, which do not allow the use of dexmedetomidine because of excessive sedative effect.

  17. Drug Metabolism by the Host and Gut Microbiota: A Partnership or Rivalry?

    PubMed

    Swanson, Hollie I

    2015-10-01

    The importance of the gut microbiome in determining not only overall health, but also in the metabolism of drugs and xenobiotics, is rapidly emerging. It is becoming increasingly clear that the gut microbiota can act in concert with the host cells to maintain intestinal homeostasis, cometabolize drugs and xenobiotics, and alter the expression levels of drug-metabolizing enzymes and transporters and the expression and activity levels of nuclear receptors. In this myriad of activities, the impact of the microbiota may be beneficial or detrimental to the host. Given that the interplay between the gut microbiota and host cells is likely subject to high interindividual variability, this work has tremendous implications for our ability to predict accurately a particular drug's pharmacokinetics and a given patient population's response to drugs. In this issue of Drug Metabolism and Disposition, a series of articles is presented that illustrate the progress and challenges that lie ahead as we unravel the intricacies associated with drug and xenobiotic metabolism by the gut microbiota. These articles highlight the underlying mechanisms that are involved and the use of in vivo and in vitro approaches that are currently available for elucidating the role of the gut microbiota in drug and xenobiotic metabolism. These articles also shed light on exciting new avenues of research that may be pursued as we consider the role of the gut microbiota as an endocrine organ, a component of the brain-gut axis, and whether the gut microbiota is an appropriate and amenable target for new drugs.

  18. Hepatic steroid inactivating enzymes, hepatic portal blood flow, and corpus luteum blood perfusion in lactating dairy cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In ruminants, a decrease in pregnancy rates may be due to decreased concentrations of progesterone (P4). It is important to note that both production from the corpus luteum and/or hepatic steroid inactivation impacts peripheral concentrations of P4. Cattle with an elevated dry matter intake have inc...

  19. Citrus unshiu peel extract ameliorates hyperglycemia and hepatic steatosis by altering inflammation and hepatic glucose- and lipid-regulating enzymes in db/db mice.

    PubMed

    Park, Hae-Jin; Jung, Un Ju; Cho, Su-Jung; Jung, Hee-Kyung; Shim, Sangphil; Choi, Myung-Sook

    2013-02-01

    Insulin resistance in Type 2 diabetes leads to hepatic steatosis that can accompanied by progressive inflammation of the liver. Citrus unshiu peel is a rich source of citrus flavonoids that possess anti-inflammatory, anti-diabetic and lipid-lowering effects. However, the ability of citrus unshiu peel ethanol extract (CPE) to improve hyperglycemia, adiposity and hepatic steatosis in Type 2 diabetes is unknown. Thus, we evaluated the effects of CPE on markers for glucose, lipid metabolism and inflammation in Type 2 diabetic mice. Male C57BL/KsJ-db/db mice were fed a normal diet with CPE (2 g/100 g diet) or rosiglitazone (0.001 g/100 g diet) for 6 weeks. Mice supplemented with the CPE showed a significant decrease in body weight gain, body fat mass and blood glucose level. The antihyperglycemic effect of CPE appeared to be partially mediated through the inhibition of hepatic gluconeogenic phosphoenolpyruvate carboxykinase mRNA expression and its activity and through the induction of insulin/glucagon secretion. CPE also ameliorated hepatic steatosis and hypertriglyceridemia via the inhibition of gene expression and activities of the lipogenic enzymes and the activation of fatty acid oxidation in the liver. These beneficial effects of CPE may be related to increased levels of anti-inflammatory adiponectin and interleukin (IL)-10, and decreased levels of pro-inflammatory markers (IL-6, monocyte chemotactic protein-1, interferon-γ and tumor necrosis factor-α) in the plasma or liver. Taken together, we suggest that CPE has the potential to improve both hyperglycemia and hepatic steatosis in Type 2 diabetes.

  20. Fundamentals of enzyme kinetics.

    PubMed

    Seibert, Eleanore; Tracy, Timothy S

    2014-01-01

    This chapter provides a general introduction to the kinetics of enzyme-catalyzed reactions, with a focus on drug-metabolizing enzymes. A prerequisite to understanding enzyme kinetics is having a clear grasp of the meanings of "enzyme" and "catalysis." Catalysts are reagents that can increase the rate of a chemical reaction without being consumed in the reaction. Enzymes are proteins that form a subset of catalysts. These concepts are further explored below.

  1. Defective Cytochrome P450-Catalysed Drug Metabolism in Niemann-Pick Type C Disease

    PubMed Central

    Wassif, Christopher A.; Gray, James; Burkert, Kathryn R.; Smith, David A.; Morris, Lauren; Cologna, Stephanie M.; Peer, Cody J.; Sissung, Tristan M.; Uscatu, Constantin-Daniel; Figg, William D.; Pavan, William J.; Vite, Charles H.; Porter, Forbes D.; Platt, Frances M.

    2016-01-01

    Niemann-Pick type C (NPC) disease is a neurodegenerative lysosomal storage disease caused by mutations in either the NPC1 or NPC2 gene. NPC is characterised by storage of multiple lipids in the late endosomal/lysosomal compartment, resulting in cellular and organ system dysfunction. The underlying molecular mechanisms that lead to the range of clinical presentations in NPC are not fully understood. While evaluating potential small molecule therapies in Npc1-/- mice, we observed a consistent pattern of toxicity associated with drugs metabolised by the cytochrome P450 system, suggesting a potential drug metabolism defect in NPC1 disease. Investigation of the P450 system in the context of NPC1 dysfunction revealed significant changes in the gene expression of many P450 associated genes across the full lifespan of Npc1-/- mice, decreased activity of cytochrome P450 reductase, and a global decrease of multiple cytochrome P450 catalysed dealkylation reactions. In vivo drug metabolism studies using a prototypic P450 metabolised drug, midazolam, confirmed dysfunction in drug clearance in the Npc1-/- mouse. Expression of the Phase II enzyme uridinediphosphate-glucuronosyltransferase (UGT) was also significantly reduced in Npc1-/- mice. Interestingly, reduced activity within the P450 system was also observed in heterozygous Npc1+/- mice. The reduced activity of P450 enzymes may be the result of bile acid deficiency/imbalance in Npc1-/- mice, as bile acid treatment significantly rescued P450 enzyme activity in Npc1-/- mice and has the potential to be an adjunctive therapy for NPC disease patients. The dysfunction in the cytochrome P450 system were recapitulated in the NPC1 feline model. Additionally, we present the first evidence that there are alterations in the P450 system in NPC1 patients. PMID:27019000

  2. Hepatic xenobiotic metabolizing enzymes in two species of benthic fish showing different prevalences of contaminant-associated liver neoplasms

    SciTech Connect

    Collier, T.K.; Singh, S.V.; Awasthi, Y.C.; Varanasi, U. )

    1992-04-01

    English sole (Parophrys vetulus) and starry flounder (Platichthys stellatus) are closely related benthic fish which show substantial differences in prevalences of contaminant-associated hepatic neoplasms and putatively preneoplastic foci of cellular alteration when captured from estuaries containing a variety of organic chemical contaminants, including polycyclic aromatic hydrocarbons (PAH) and chlorinated hydrocarbons. Because PAH are strongly implicated as causative agents in the etiology of these lesions, several of the hepatic enzymes involved in activation and detoxication of PAH were studied in these two species. Hepatic aryl hydrocarbon hydroxylase (AHH), epoxide hydrolase (EH), and glutathione S-transferase (GST) activities were measured in animals sampled from both contaminated and reference areas. English sole, the species showing higher prevalences of contaminant-associated hepatic lesions, had higher (1- to 2-fold) hepatic activities of AHH and lower activities of EH (0.8-fold) and GST (1.8-fold) than those of starry flounder, regardless of site of capture. These results are largely consistent with increased activation and decreased detoxication of PAH by English sole in comparison to starry flounder. Both laboratory and field data suggested that the observed species differences in enzyme activities were constitutive and not related to differential exposure to contaminants. There were also substantial differences between these species with respect to expression of GST isoenzymes, in that starry flounder expressed two highly anionic GST isoenzymes which did not correspond to any GST isoenzymes expressed in English sole liver; a previous study in an elasmobranch fish showed that an anionic GST was most active toward PAH oxides.

  3. [Enzyme alterations during chemical hepatocarcinogenesis].

    PubMed

    Sato, K; Satoh, K; Hatayama, I

    1987-06-01

    Biochemical phenotypes such as the forms of enzyme proteins alter during the promotion and progression stages in chemical hepatocarcinogenesis. Many enzymes or isoenzymes have been identified as markers of (pre) neoplastic hepatic tissues and used for analysis of the carcinogenic process. The levels of hepatic isoenzymes decrease and those of prototypic or fetal isozymes increase during the progression of hepatocarcinogenesis. Some drug-metabolizing enzymes are also very variable at the promotion stage in rat chemical carcinogenesis; Phase I enzymes such as cytochrome P-450 decrease and Phase II (iso)-enzymes such as UDP-glucuronyl-transferase, glutathione S-transferase (GST) and gamma-glutamyl transpeptidase (gamma-GTP) increase. A new neutral GST form with pI 7.0 (GST-P) has been identified by us as one of the best markers for rat chemical hepatocarcinogenesis. GST-P is a homodimer consisting of a subunit (Mr 26,000, more accurately 23,307, and pI 6.7), the smallest among rat GST subunits, and differs immunochemically from any other GST form. It is present in very low levels in normal rat liver and is not inducible by most drugs including carcinogens without the appearance of preneoplastic hepatocyte nodules (HN) but it is increased by several ten-fold in HN-bearing liver and hepatomas induced by different carcinogens. Immunohistochemically, it is localized in HN and very early and small GST-positive foci are detectable using anti-GST-P antibody. (Pre) neoplastic hepatic lesions induced by nongenotoxic carcinogens such as hypolipidemic peroxisome-proliferating agents do not express GST-P as well as gamma-GTP.

  4. Enzyme

    MedlinePlus

    Enzymes are complex proteins that cause a specific chemical change in all parts of the body. For ... use them. Blood clotting is another example of enzymes at work. Enzymes are needed for all body ...

  5. Effects of Radiation and Dietary Iron on Expression of Genes and Proteins Involved in Drug Metabolism

    NASA Technical Reports Server (NTRS)

    Faust, K. M.; Wotring, V. E.

    2014-01-01

    Liver function, especially the rate of metabolic enzyme activities, determines the concentration of circulating drugs and the duration of their efficacy. Most pharmaceuticals are metabolized by the liver, and clinically-used medication doses are given with normal liver function in mind. A drug overdose can result in the case of a liver that is damaged and removing pharmaceuticals from the circulation at a rate slower than normal. Alternatively, if liver function is elevated and removing drugs from the system more quickly than usual, it would be as if too little drug had been given for effective treatment. Because of the importance of the liver in drug metabolism, we want to understand any effects of spaceflight on the enzymes of the liver. Dietary factors and exposure to radiation are aspects of spaceflight that are potential oxidative stressors and both can be modeled in ground experiments. In this experiment, we examined the effects of high dietary iron and low dose gamma radiation (individually and combined) on the gene expression of enzymes involved in drug metabolism, redox homeostasis, and DNA repair. METHODS All procedures were approved by the JSC Animal Care and Use Committee. Male Sprague-Dawley rats were divided into 4 groups (n=8); control, high Fe diet (650 mg iron/kg), radiation (fractionated 3 Gy exposure from a Cs- 137 source) and combined high Fe diet + radiation exposure. Animals were euthanized 24h after the last treatment of radiation; livers were removed immediately and flash -frozen in liquid nitrogen. Expression of genes thought to be involved in redox homeostasis, drug metabolism and DNA damage repair was measured by RT-qPCR. Where possible, protein expression of the same genes was measured by western blotting. All data are expressed as % change in expression normalized to reference gene expression; comparisons were then made of each treatment group to the sham exposed/ normal diet control group. Data was considered significant at p< 0

  6. Hepatitis A

    MedlinePlus

    ... transaminase enzyme levels Treatment There is no specific treatment for hepatitis A. You should rest when the symptoms are ... and have not had hepatitis A or the hepatitis A vaccine. Common reasons for getting one or both of these treatments include: You live with someone who has hepatitis ...

  7. Effect of the combined probiotics with aflatoxin B₁-degrading enzyme on aflatoxin detoxification, broiler production performance and hepatic enzyme gene expression.

    PubMed

    Zuo, Rui-yu; Chang, Juan; Yin, Qing-qiang; Wang, Ping; Yang, Yu-rong; Wang, Xiao; Wang, Guo-qiang; Zheng, Qiu-hong

    2013-09-01

    In order to degrade aflatoxin B₁ (AFB₁), AFB₁-degrading microbes (probiotics) such as Lactobacillus casei, Bacillus subtilis and Pichia anomala, and the AFB₁-degrading enzyme from Aspergillus oryzae were selected and combined to make feed additive. Seventy-five 43-day-old male Arbor Acres broilers were randomly divided into 5 groups, 15 broilers for each group. The broilers were given with 5 kinds of diets such as the basal diet, 400 μg/kg AFB₁ supplement without feed additive, and 200, 400, 800 μg/kg AFB₁ supplement with 0.15% feed additive. The feeding experimental period was 30 d, which was used to determine production performance of broilers. In addition, serum, liver and chest muscle were selected for measuring AFB₁ residues, gene expressions, microscopic and antioxidant analyses. The results showed that adding 0.15% feed additive in broiler diets could significantly relieve the negative effect of AFB₁ on chicken's production performance and nutrient metabolic rates (P<0.05). It could also improve AFB₁ metabolism, hepatic cell structure, antioxidant activity, and many hepatic enzyme gene expressions involved in oxidoreductase, apoptosis, cell growth, immune system and metabolic process (P<0.05). It could be concluded that the feed additive was able to degrade AFB₁ and improve animal production.

  8. Effects of PCBs on plasma enzymes, testosterone level, and hepatic xenobiotic metabolism in the grey partridge, perdix perdlx

    SciTech Connect

    Abiola, F. ); Lorgue, G.; Riviere, J.L. ); Benoit, E. ); Soyez, D. )

    1989-09-01

    The hepatic cytochrome P-450-dependent monooxygenase (MO) system functions in oxidative biotransformation of a wide variety of both endogenous and exogenous (xenobiotic) compounds in many animal species. However, most of the previous studies were carried out with a narrow range of species and investigations on wild species are lacking. In this report, the authors describe the effects of a commercial mixture of PCBs (DP5) on the hepatic MO activities of the grey partridge (Perdix perdix). To more thoroughly investigate the inducing effects of DP5, they used two series of homologous substrates, alkylresorufins and alkoxycoumarins, and an endogenous compound, testosterone, which were shown in mammals to differentiate between different forms of cytochrome P-450. Furthermore, to more carefully assess the effects of DP5, they also measured the activity of two plasma marker enzymes, alanine transpeptidase (ALAT) and gamma-glutamyl transferase (gamma-GT), and the plasmatic concentration of testosterone.

  9. Stimulation of drug metabolism by rifampicin in patients with cirrhosis or cholestasis measured by increased hexobarbital and tolbutamide clearance.

    PubMed

    Zilly, W; Breimer, D D; Richter, E

    1977-04-20

    Eleven patients with hepatic cirrhosis or cholestasis were treated with rifampicin for 7 to 132 days. Ten patients received hexobarbital (7.32 mg/kg) and five received tolbutamide (20 mg/kg) by i.v. infusion prior to and after rifampicin treatment; plasma concentrations of the two test compounds were determined during and after infusion. The average elimination half-life of hexobarbital had decreased from 624 to 262 min and that of tolbutamide from 292 to 160 min following rifampicin treatment. It was calculated that the metabolic clearance of hexobarbital had increased more than two-fold and that of tolbutamide almost two-fold. The results suggests that rifampicin is able to stimulate hepatic drug metabolism in patients with liver disease. It was apparent in general that the induction did not lead to improvement of hepatocellular function during disease as judged by laboratory findings.

  10. Angiotensin-converting enzyme 2/angiotensin-(1–7)/Mas axis activates Akt signaling to ameliorate hepatic steatosis

    PubMed Central

    Cao, Xi; Yang, Fangyuan; Shi, Tingting; Yuan, Mingxia; Xin, Zhong; Xie, Rongrong; Li, Sen; Li, Hongbing; Yang, Jin-Kui

    2016-01-01

    The classical axis of renin-angiotensin system (RAS), angiotensin (Ang)-converting enzyme (ACE)/Ang II/AT1, contributes to the development of non-alcoholic fatty liver disease (NAFLD). However, the role of bypass axis of RAS (Angiotensin-converting enzyme 2 (ACE2)/Ang-(1–7)/Mas) in hepatic steatosis is still unclear. Here we showed that deletion of ACE2 aggravates liver steatosis, which is correlated with the increased expression of hepatic lipogenic genes and the decreased expression of fatty acid oxidation-related genes in the liver of ACE2 knockout (ACE2−/y) mice. Meanwhile, oxidative stress and inflammation were also aggravated in ACE2−/y mice. On the contrary, overexpression of ACE2 improved fatty liver in db/db mice, and the mRNA levels of fatty acid oxidation-related genes were up-regulated. In vitro, Ang-(1–7)/ACE2 ameliorated hepatic steatosis, oxidative stress and inflammation in free fatty acid (FFA)-induced HepG2 cells, and what’s more, Akt inhibitors reduced ACE2-mediated lipid metabolism. Furthermore, ACE2-mediated Akt activation could be attenuated by blockade of ATP/P2 receptor/Calmodulin (CaM) pathway. These results indicated that Ang-(1–7)/ACE2/Mas axis may reduce liver lipid accumulation partly by regulating lipid-metabolizing genes through ATP/P2 receptor/CaM signaling pathway. Our findings support the potential role of ACE2/Ang-(1–7)/Mas axis in prevention and treatment of hepatic lipid metabolism. PMID:26883384

  11. Omics Approaches To Probe Microbiota and Drug Metabolism Interactions.

    PubMed

    Nichols, Robert G; Hume, Nicole E; Smith, Philip B; Peters, Jeffrey M; Patterson, Andrew D

    2016-12-19

    The drug metabolism field has long recognized the beneficial and sometimes deleterious influence of microbiota in the absorption, distribution, metabolism, and excretion of drugs. Early pioneering work with the sulfanilamide precursor prontosil pointed toward the necessity not only to better understand the metabolic capabilities of the microbiota but also, importantly, to identify the specific microbiota involved in the generation and metabolism of drugs. However, technological limitations important for cataloging the microbiota community as well as for understanding and/or predicting their metabolic capabilities hindered progress. Current advances including mass spectrometry-based metabolite profiling as well as culture-independent sequence-based identification and functional analysis of microbiota have begun to shed light on microbial metabolism. In this review, case studies will be presented to highlight key aspects (e.g., microbiota identification, metabolic function and prediction, metabolite identification, and profiling) that have helped to clarify how the microbiota might impact or be impacted by drug metabolism. Lastly, a perspective of the future of this field is presented that takes into account what important knowledge is lacking and how to tackle these problems.

  12. Effects of dietary phenochlor DP5 on microsomal enzymes, liver, and blood lipids in adult male and female rats after subchronic and perinatal exposures

    SciTech Connect

    Poul, J.M.

    1987-08-01

    PCBs have numerous toxic effects on laboratory animals, namely hepatotoxicity, immunotoxicity, reproductive and hormonal effects, mutagenic and carcinogenic potency (Safe 1984). They have been recognized as potent inducers of many microsomal drug metabolizing enzymes in several species. Moreover, treatment of rats with PCBs gave rise to altered lipid metabolism with accumulation of lipids in the liver. In most of these studies male rats have been used. However, sex differences in the effects of xenobiotics on microsomal drug metabolizing enzymes have been shown particularly with PCBs and little was known about differences in the effects of PCBs on lipid metabolism. This study was designed to investigate the effects of a subchronic treatment with Phenochlor DP5 on some microsomal drug metabolizing enzyme activities and on liver and blood lipids of male and female rats. The long-term effects of DP5 administration during pre and postnatal period on adult microsomal enzyme activities and liver and blood lipids of both sexes have also been studied. A possible xenobiotic imprinting of the hepatic monooxygenase system during neonatal period has been shown recently, and it has been recognized that some functional defects which often manifest themselves in adult period may be induced prenatally or before weaning.

  13. Hepatic antioxidant enzymes SOD and CAT of Nile tilapia (Oreochromis niloticus) in response to pesticide methomyl and recovery pattern.

    PubMed

    Meng, Shun Long; Chen, Jia Zhang; Xu, Pao; Qu, Jian Hong; Fan, Li Min; Song, Chao; Qiu, Li Ping

    2014-04-01

    Hepatic antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) of Nile tilapia in response to pesticide methomyl and recovery pattern were researched by exposing tilapia to sub-lethal methomyl concentrations of 0, 0.2, 2, 20 and 200 μg/L for 30 days, and then transferred to methomyl-free water for 18 days. Hepatic SOD and CAT were measured at 10 min (day 0), 6, 12, 18, 24 and 30 days after starting the experiment and at 18 days after transferring to methomyl-free water. The results showed hepatic SOD and CAT activities in 2, 20 and 200 μg/L groups were affected significantly, however, that in 0.2 μg/L group didn't change significantly compared to control during 30-day exposure period. Thus it would appear the 0.2 μg/L methomyl might be considered the no observed adverse effect level. Recovery data showed that, for SOD, the effects produced by lower concentration of methomyl 2 μg/L were reversible but not at concentrations higher than 20 μg/L, however, for CAT, the effects produced by all the concentrations were reversible.

  14. Activity and mRNA Levels of Enzymes Involved in Hepatic Fatty Acid Synthesis in Rats Fed Naringenin.

    PubMed

    Hashimoto, Toru; Ide, Takashi

    2015-11-04

    We investigated the physiological activity of naringenin in affecting hepatic lipogenesis and serum and liver lipid levels in rats. Rats were fed diets containing 0, 1, or 2.5 g/kg naringenin for 15 d. Naringenin at a dietary level of 2.5 g/kg significantly decreased the activities and the mRNA levels of various lipogenic enzymes and sterol regulatory element binding protein-1c (SREBP-1c) mRNA level. The activities and the mRNA levels were also 9-22% and 12-38% lower, respectively, in rats fed a 1 g/kg naringenin diet than in the animals fed a naringenin-free diet, although the differences were not significant in many cases. Naringenin at 2.5 g/kg significantly lowered serum triacylglycerol, cholesterol, and phospholipid and hepatic triacylglycerol and cholesterol. This flavonoid at 1.0 g/kg also significantly lowered these parameters except for serum triacylglycerol. Naringenin levels in serum and liver dose-dependently increased, and hepatic concentrations reached levels that can affect various signaling pathways.

  15. Hepatic cytochrome P450 enzymes belonging to the CYP2C subfamily from an Australian marsupial, the koala (Phascolarctos cinereus).

    PubMed

    Jones, Brett R; El-Merhibi, Adaweyah; Ngo, Suong N T; Stupans, Ieva; McKinnon, Ross A

    2008-09-01

    Cytochromes P450 (CYPs) are critically important in the oxidative metabolism of a diverse array of xenobiotics and endogenous substrates. We have previously reported that the obligate Eucalyptus feeder koala (Phascolarctos cinereus) exhibits a higher hepatic CYP2C activity as compared to non-Eucalyptus feeders human or rat, with stimulation of CYP2C activity by cineole. In the present study, we examine CYP2C expression by immunohistochemistry and describe the identification and cloning of koala CYP2Cs. Utilising anti-rat CYP2C6 antibody, the expression of CYP2C was found to be uniform across the hepatic sections, being consistent with that observed in human and rat. Two 1647 and 1638 bp koala liver CYP2C complete cDNAs, designated CYP2C47 and CYP2C48 respectively, were cloned by cDNA library screening. The koala CYP2C cDNAs encode a protein of 495 amino acids. Three additional partial CYP2C sequences were also identified from the koala, indicating the multiplicity of the CYP2C subfamily in this unique marsupial species. The results of this study demonstrate the presence of koala hepatic CYP2Cs that share several common features with other published CYP2Cs; however CYP2C47 and CYP2C48 contain four extra amino acid residues at the NH2-terminal, a transmembrane anchor which was reported being a fundamentally conserved structure core of all eukaryote CYP enzymes.

  16. Drug Metabolism by the Host and Gut Microbiota: A Partnership or Rivalry?

    PubMed Central

    2015-01-01

    The importance of the gut microbiome in determining not only overall health, but also in the metabolism of drugs and xenobiotics, is rapidly emerging. It is becoming increasingly clear that the gut microbiota can act in concert with the host cells to maintain intestinal homeostasis, cometabolize drugs and xenobiotics, and alter the expression levels of drug-metabolizing enzymes and transporters and the expression and activity levels of nuclear receptors. In this myriad of activities, the impact of the microbiota may be beneficial or detrimental to the host. Given that the interplay between the gut microbiota and host cells is likely subject to high interindividual variability, this work has tremendous implications for our ability to predict accurately a particular drug’s pharmacokinetics and a given patient population’s response to drugs. In this issue of Drug Metabolism and Disposition, a series of articles is presented that illustrate the progress and challenges that lie ahead as we unravel the intricacies associated with drug and xenobiotic metabolism by the gut microbiota. These articles highlight the underlying mechanisms that are involved and the use of in vivo and in vitro approaches that are currently available for elucidating the role of the gut microbiota in drug and xenobiotic metabolism. These articles also shed light on exciting new avenues of research that may be pursued as we consider the role of the gut microbiota as an endocrine organ, a component of the brain-gut axis, and whether the gut microbiota is an appropriate and amenable target for new drugs. PMID:26261284

  17. Application of quantitative targeted absolute proteomics to profile protein expression changes of hepatic transporters and metabolizing enzymes during cholic acid-promoted liver regeneration.

    PubMed

    Miura, Takayuki; Tachikawa, Masanori; Ohtsuka, Hideo; Fukase, Koji; Nakayama, Shun; Sakata, Naoaki; Motoi, Fuyuhiko; Naitoh, Takeshi; Katayose, Yu; Uchida, Yasuo; Ohtsuki, Sumio; Terasaki, Tetsuya; Unno, Michiaki

    2017-02-26

    Preoperative administration of cholic acid (CA) may be an option to increase the liver volume before elective liver resection surgery, so it is important to understand its effects on liver functionality for drug transport and metabolism. The purpose of this study was to clarify the absolute protein expression dynamics of transporters and metabolizing enzymes in the liver of mice fed CA-containing diet for 5 days (CA1) and mice fed CA-containing diet for 5 days followed by diet without CA for 7 days (CA2), in comparison with non CA-fed control mice. The CA1 group showed the increased liver weight, cell proliferation index, and oxidative stress, but no increase of apoptosis. Quantitative targeted absolute proteomics revealed (i) decreases in basolateral bile acid transporters ntcp, oatp1a1, oatp1b2, bile acid synthesis-related enzymes cyp7a1 and cyp8b1, and drug transporters bcrp, mrp6, ent1, oatp2b1, and (ii) increases in glutathione biosynthetic enzymes and drug-metabolizing enzyme cyp3a11. Liver concentrations of reduced and oxidized glutathione were both increased. In the CA2 group, the increased liver weight was maintained, while the biochemical features and protein profiles were restored to the non-CA-fed control levels. These findings suggest that CA administration alters liver functionality per body during liver regeneration and restoration.

  18. Effect of long-term phenothiazine treatment on drug metabolism.

    PubMed Central

    Kolakowska, T; Franklin, M; Alapin, B

    1975-01-01

    1 The half-life of plasma antipyrine was measured in twelve chronic schizophrenic patients during long-term phenothiazine treatment and again following 4-5 weeks on placebo. 2 The mean antipyrine half-life was low during phenothiazine administration (6.1 +/- 4.2 h), rising after withdrawal of drugs to the range reported for untreated subjects by other authors (9.5 +/- 4.2 h). The prolongation of antipyrine half-life following the drug-free period occurred in nine of twelve subjects and the difference was significant for the group at P less than 0.05. 3 The finding suggests that prolonged administration of phenothiazines stimulates the rate of drug metabolism. PMID:1234485

  19. Update information on drug metabolism systems--2009, part I.

    PubMed

    Guengerich, F Peter; Rendic, Slobodan

    2010-01-01

    The field of drug metabolism has changed dramatically in the past generation. Two of the driving forces are the advances in analytical chemistry and our understanding of the biological systems. With regard to the former, the advances in liquid chromatography-mass spectrometry (LC-MS) are extremely impressive, and the speed of analysis has been increased even more with the recent developments in ultraperformance LC (UPLC). NMR analysis on a sub-microgram scale is not unusual, and the 2-dimensional methods are also very impressive. The biology underlying gene regulation is highly developed, and the recombinant methods have greatly facilitated progress in the field. Today it is common to design discovery and development efforts focused on critical human phenomena from the very start, with animal studies supporting the efficacy and safety efforts.

  20. DEHP reduces thyroid hormones via interacting with hormone synthesis-related proteins, deiodinases, transthyretin, receptors, and hepatic enzymes in rats.

    PubMed

    Liu, Changjiang; Zhao, Letian; Wei, Li; Li, Lianbing

    2015-08-01

    Di-(2-ethylhexyl) phthalate (DEHP) is used extensively in many personal care and consumer products, resulting in widespread nonoccupational human exposure through multiple routes and media. Limited studies suggest that exposure to DEHP may be associated with altered thyroid function, but detailed mechanisms are unclear. In order to elucidate potential mechanisms by which DEHP disturbs thyroid hormone homeostasis, Sprague-Dawley (SD) rats were dosed with DEHP by gavage at 0, 250, 500, and 750 mg/kg/day for 30 days and sacrificed within 24 h after the last dose. Gene expressions of thyroid hormone receptors, deiodinases, transthyretin, and hepatic enzymes were measured by RT-PCR; protein levels of transthyretin were also analyzed by Western blot. Results showed that DEHP caused histological changes in the thyroid and follicular epithelial cell hypertrophy and hyperplasia were observed. DEHP significantly reduced thyroid hormones (T3, T4) and thyrotropin releasing hormone (TRH) levels, whereas thyroid stimulating hormone (TSH) was not affected. After exposure to DEHP, biosynthesis of thyroid hormones was suppressed, and sodium iodide symporter (NIS) and thyroid peroxidase (TPO) levels were significantly reduced. Additionally, levels of deiodinases and transthyretin were also affected. TSH receptor (TSHr) level was downregulated, while TRH receptor (TRHr) level was upregulated. Metabolism of thyroid hormones was accelerated due to elevated gene expression of hepatic enzymes (UDPGTs and CYP2B1) by DEHP. Taken together, observed findings indicate that DEHP could reduce thyroid hormones through influencing biosynthesis, biotransformation, biotransport, receptor levels, and metabolism of thyroid hormones.

  1. Hepatic cannabinoid receptor type 1 mediates alcohol-induced regulation of bile acid enzyme genes expression via CREBH.

    PubMed

    Chanda, Dipanjan; Kim, Yong-Hoon; Li, Tiangang; Misra, Jagannath; Kim, Don-Kyu; Kim, Jung Ran; Kwon, Joseph; Jeong, Won-Il; Ahn, Sung-Hoon; Park, Tae-Sik; Koo, Seung-Hoi; Chiang, John Y L; Lee, Chul-Ho; Choi, Hueng-Sik

    2013-01-01

    Bile acids concentration in liver is tightly regulated to prevent cell damage. Previous studies have demonstrated that deregulation of bile acid homeostasis can lead to cholestatic liver disease. Recently, we have shown that ER-bound transcription factor Crebh is a downstream effector of hepatic Cb1r signaling pathway. In this study, we have investigated the effect of alcohol exposure on hepatic bile acid homeostasis and elucidated the mediatory roles of Cb1r and Crebh in this process. We found that alcohol exposure or Cb1r-agonist 2-AG treatment increases hepatic bile acid synthesis and serum ALT, AST levels in vivo alongwith significant increase in Crebh gene expression and activation. Alcohol exposure activated Cb1r, Crebh, and perturbed bile acid homeostasis. Overexpression of Crebh increased the expression of key bile acid synthesis enzyme genes via direct binding of Crebh to their promoters, whereas Cb1r knockout and Crebh-knockdown mice were protected against alcohol-induced perturbation of bile acid homeostasis. Interestingly, insulin treatment protected against Cb1r-mediated Crebh-induced disruption of bile acid homeostasis. Furthermore, Crebh expression and activation was found to be markedly increased in insulin resistance conditions and Crebh knockdown in diabetic mice model (db/db) significantly reversed alcohol-induced disruption of bile acid homeostasis. Overall, our study demonstrates a novel regulatory mechanism of hepatic bile acid metabolism by alcohol via Cb1r-mediated activation of Crebh, and suggests that targeting Crebh can be of therapeutic potential in ameliorating alcohol-induced perturbation of bile acid homeostasis.

  2. Induction of hepatic CYP3A enzymes by pregnancy-related hormones: studies in human hepatocytes and hepatic cell lines.

    PubMed

    Papageorgiou, Ioannis; Grepper, Susan; Unadkat, Jashvant D

    2013-02-01

    CYP3A activity is induced by approximately 2-fold during the third trimester of human pregnancy. Placental growth hormone (PGH), estrogens (primarily 17β-estradiol), cortisol, and progesterone have the potential to modulate CYP3A activity. Therefore, we determined whether the elevated plasma concentrations of these hormones during pregnancy induce hepatic CYP3A expression. We incubated sandwich-cultured human hepatocytes (SCHH) from premenopausal female donors (n = 2) with the physiologic (unbound, 1× total) and the 10× total third trimester hormone plasma concentrations (individually and in combination) and determined their effect on CYP3A activity and the transcripts of CYP3A4, CYP3A5, and the respective hormone receptors (growth hormone receptor, glucocorticoid receptor, and estrogen receptor alpha). Of all the hormones, cortisol was the most potent inducer of CYP3A activity and CYP3A4, CYP3A5 mRNA expression. The combination of PGH/growth hormone and cortisol induced CYP3A activity and expression significantly more than did cortisol alone. When incubated with the unbound or total plasma concentration of all the hormones, CYP3A activity in SCHH was induced to an extent comparable to that observed in vivo during the third trimester. These hormones had only a modest effect on the mRNA expression of the hormone receptors. The pattern of induction observed in SCHH was reproduced in HepaRG cells but not in HuH7/HepG2 cells. SCHH or HepaRG cells could be used to determine the mechanistic basis of CYP3A induction during pregnancy and to predict the magnitude of induction likely to be observed during the first and second trimesters, when phenotyping studies to measure in vivo CYP3A activity are logistically difficult to perform.

  3. Chemomodulatory effect of Moringa oleifera, Lam, on hepatic carcinogen metabolising enzymes, antioxidant parameters and skin papillomagenesis in mice.

    PubMed

    Bharali, Rupjyoti; Tabassum, Jawahira; Azad, Mohammed Rekibul Haque

    2003-01-01

    The modulatory effects of a hydro-alcoholic extract of drumsticks of Moringa oliefera Lam at doses of 125 mg/kg bodyweight and 250 mg/ kg body weight for 7 and 14 days, respectively, were investigated with reference to drug metabolising Phase I (Cytochrome b(5) and Cytochrome p(450) ) and Phase II (Glutathione-S- transferase) enzymes, anti-oxidant enzymes, glutathione content and lipid peroxidation in the liver of 6-8 week old female Swiss albino mice. Further, the chemopreventive efficacy of the extract was evaluated in a two stage model of 7,12 - dimethylbenz(a)anthracene induced skin papillomagenesis. Significant increase (p<0.05 to p<0.01) in the activities of hepatic cytochrome b(5), cytochrome p(450), catalase, glutathione peroxidase ( GPx ), glutathione reductase (GR), acid soluble sulfhydryl content (-SH ) and a significant decrease ( p<0.01 ) in the hepatic MDA level were observed at both dose levels of treatment when compared with the control values. Glutathione-S- transferase ( GST )activity was found to be significantly increased (p<0.01 ) only at the higher dose level. Butylated hydroxyanisol (BHA ) fed at a dose of 0.75% in the diet for 7 and 14 days (positive control ) caused a significant increase (p<0.05 to p<0.01) in the levels of hepatic phase I and phase II enzymes, anti- oxidant enzymes, glutathione content and a decrease in lipid peroxidation. The skin papillomagenesis studies demonstrated a significant decrease (p<0.05 ) in the percentage of mice with papillomas, average number of papillomas per mouse and papillomas per papilloma bearing mouse when the animals received a topical application of the extract at a dose of 5mg/ kg body weight in the peri-initiation phase 7 days before and 7 days after DMBA application, Group II ), promotional phase (from the day of croton oil application and continued till the end of the experiment, Group III ) and both peri and post initiation stages (from 7 days prior to DMBA application and continued till the

  4. Effects of hepatic enzyme inducers on thyroxine (T4) catabolism in primary rat hepatocytes

    EPA Science Inventory

    Nuclear receptor agonists such as phenobarbital (PB), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153), and 3-methylcholantrene (3-MC) decrease circulating thyroxine (T4) concentrations in rats. It is suspected that this decrease occurs through the induction of hepatic metabolizing en...

  5. The effect of therapeutic hypothermia on drug metabolism and drug response: cellular mechanisms to organ function

    PubMed Central

    Zhou, Jiangquan; Poloyac, Samuel M.

    2011-01-01

    Introduction Therapeutic hypothermia is being employed, clinically based, on its neuro-protective benefits. Both critical illness and therapeutic hypothermia significantly affect drug disposition, potentially contributing to drug-therapy and drug-disease interaction. Currently, there is limited written information of the known alterations in drug concentration and response during mild hypothermia treatment and there is a limited understanding of the specific mechanisms that underlie alterations in drug concentrations and the potential clinical importance of these changes. Areas covered A systemic review of the effect of therapeutic hypothermia on drug metabolism, disposition, and response is provided. Specifically, the clinical and preclinical evidence of the effects of therapeutic hypothermia on blood flow, specific hepatic metabolism pathways, transporter, renal excretion, pharmacodynamics and rewarming effect are reviewed. Expert Opinion Available evidence demonstrates that mild hypothermia decreases the clearance of a variety of drugs with apparently little change in drug protein binding. Recent evidence suggests that the magnitude of the change is elimination route specific. Further research is needed to determine the impact of these alterations on both drug concentration and response in order to optimize the hypothermia therapy in this vulnerable patient population. PMID:21473710

  6. Sex difference in induction of hepatic CYP2B and CYP3A subfamily enzymes by nicardipine and nifedipine in rats.

    PubMed

    Konno, Yoshihiro; Sekimoto, Masashi; Nemoto, Kiyomitsu; Degawa, Masakuni

    2004-04-01

    Male and female of F344 rats were treated per os with nicardipine (Nic) and nifedipine (Nif), and changes in the levels of mRNA and protein of hepatic cytochrome P450 (P450) enzymes, CYP2B1, CYP2B2, CYP3A1, CYP3A2, CYP3A9, and CYP3A18 were examined. Furthermore, hepatic microsomal activities for pentoxyresorufin O-dealkylation (PROD) and nifedipine oxidation, which are mainly mediated by CYP2B and CYP3A subfamily enzymes, respectively, were measured. Analyses of RT-PCR and Western blotting revealed that Nic and Nif induced predominantly CYP3A and CYP2B enzymes, respectively. As for the gene activation of CYP2B enzymes, especially CYP2B1, Nif showed high capacity in both sexes of rats, whereas Nic did a definite capacity in the males but little in the females. Gene activations of CYP3A1, CYP3A2, and CYP3A18 by Nic occurred in both sexes of rats, although that of CYP3A9 did only in the male rats. Although gene activations of CYP3A1 and CYP3A2 by Nif were observed in both sexes of rats, a slight activation of the CYP3A9 gene occurred only in female rats, and the CYP3A18 gene activation, in neither male nor female rats. Thus, changes in levels of the mRNA or protein of CYP2B and CYP3A enzymes, especially CYP2B1 and CYP3A2, were closely correlated with those in hepatic PROD and nifedipine oxidation activities, respectively. The present findings demonstrate for the first time the sex difference in the Nic- and Nif-mediated induction of hepatic P450 enzymes in rats and further indicate that Nic and Nif show different specificities and sex dependencies in the induction of hepatic P450 enzymes.

  7. Antihypertensive Drugs Metabolism: An Update to Pharmacokinetic Profiles and Computational Approaches

    PubMed Central

    Zisaki, Aikaterini; Miskovic, Ljubisa; Hatzimanikatis, Vassily

    2015-01-01

    Drug discovery and development is a high-risk enterprise that requires significant investments in capital, time and scientific expertise. The studies of xenobiotic metabolism remain as one of the main topics in the research and development of drugs, cosmetics and nutritional supplements. Antihypertensive drugs are used for the treatment of high blood pressure, which is one the most frequent symptoms of the patients that undergo cardiovascular diseases such as myocardial infraction and strokes. In current cardiovascular disease pharmacology, four drug clusters - Angiotensin Converting Enzyme Inhibitors, Beta-Blockers, Calcium Channel Blockers and Diuretics - cover the major therapeutic characteristics of the most antihypertensive drugs. The pharmacokinetic and specifically the metabolic profile of the antihypertensive agents are intensively studied because of the broad inter-individual variability on plasma concentrations and the diversity on the efficacy response especially due to the P450 dependent metabolic status they present. Several computational methods have been developed with the aim to: (i) model and better understand the human drug metabolism; and (ii) enhance the experimental investigation of the metabolism of small xenobiotic molecules. The main predictive tools these methods employ are rule-based approaches, quantitative structure metabolism/activity relationships and docking approaches. This review paper provides detailed metabolic profiles of the major clusters of antihypertensive agents, including their metabolites and their metabolizing enzymes, and it also provides specific information concerning the computational approaches that have been used to predict the metabolic profile of several antihypertensive drugs. PMID:25341854

  8. Phenobarbital in the genetically obese Zucker rat. II. In vivo and in vitro assessments of microsomal enzyme induction.

    PubMed

    Brouwer, K L; Kostenbauder, H B; McNamara, P J; Blouin, R A

    1984-12-01

    In vivo and in vitro alterations in drug metabolism and the extent of enzyme induction of the hepatic microsomal cytochrome P-450 system were evaluated in obese and lean Zucker and lean Sprague-Dawley rats. Phenobarbital enzyme-inducing regimens were administered p.o. to achieve similar steady-state phenobarbital plasma concentrations. Control rats received p.o. placebo solution. No significant intra- or inter-strain differences in antipyrine clearance (milliliters per hour) or apparent volume of distribution (liters) were observed between the placebo-treated lean Sprague-Dawley, lean Zucker and obese Zucker rats. Intra- and inter-strain differences in hepatic microsomal protein and cytochrome P-450 content were observed. Compared to placebo, antipyrine clearance (milliliters per hour) after chronic phenobarbital pretreatment was increased in the Sprague-Dawley (198%) and lean Zucker rats (131%), but not significantly altered in the obese Zucker rats. Similarly, increases in hepatic weight, whole liver microsomal protein and cytochrome P-450 content were also observed in the Sprague-Dawley (34, 124 and 352%, respectively) and the lean Zucker rats (24, 96 and 249%, respectively). However, no significant alterations in these parameters were observed in the obese Zucker rats after phenobarbital treatment. Results from these in vivo and in vitro studies implicate alterations in drug metabolism and genetic differences in cytochrome P-450 content in Zucker rats relative to the Sprague-Dawley strain. Obese Zucker rats failed to exhibit a significant induction response after phenobarbital pretreatment.

  9. Drug Metabolism in Preclinical Drug Development: A Survey of the Discovery Process, Toxicology, and Computational Tools.

    PubMed

    Issa, Naiem T; Wathieu, Henri; Ojo, Abiola; Byers, Stephen W; Dakshanamurthy, Sivanesan

    2017-03-15

    Increased R & D spending and high failure rates exist in drug development, due in part to inadequate prediction of drug metabolism and its consequences in the human body. Hence, there is a need for computational methods to supplement and complement current biological assessment strategies. In this review, we provide an overview of drug metabolism in pharmacology, and discuss the current in vitro and in vivo strategies for assessing drug metabolism in preclinical drug development. We highlight computational tools available to the scientific community for the in silico prediction of drug metabolism, and examine how these tools have been implemented to produce drug-target signatures relevant to metabolic routes. Computational workflows that assess drug metabolism and its toxicological and pharmacokinetic effects, such as by applying the adverse outcome pathway framework for risk assessment, may improve the efficiency and speed of preclinical drug development.

  10. The trans-10,cis-12 isomer of conjugated linoleic acid reduces hepatic triacylglycerol content without affecting lipogenic enzymes in hamsters.

    PubMed

    Zabala, Amaia; Churruca, Itziar; Macarulla, M Teresa; Rodríguez, Víctor M; Fernández-Quintela, Alfredo; Martínez, J Alfredo; Portillo, María P

    2004-09-01

    Conjugated linoleic acid (CLA) refers to the positional and geometric dienoic isomers of linoleic acid. The dietary intake of CLA has been associated with changes in lipid metabolism. The aim of the present work was to assess the effects of the two main isomers of CLA on sterol regulatory element binding protein (SREBP)-1a and SREBP-1c mRNA levels, as well as on mRNA levels and the activities of several lipogenic enzymes in liver. For this purpose hamsters were fed an atherogenic diet supplemented with 5 g linoleic acid, cis-9,trans-11 or trans-10,cis-12 CLA/kg diet for 6 weeks. The trans-10,cis-12 isomer intake produced significantly greater liver weight, but also significantly decreased liver fat accumulation. No changes in mRNA levels of SREBP-1a, SREBP-1c and lipogenic enzymes, or in the activities of these enzymes, were observed. There was no effect of feeding cis-9,trans-11 CLA. These results suggest that increased fat accumulation in liver does not occur on the basis of liver enlargement produced by feeding the trans-10,cis-12 isomer of CLA in hamsters. The reduction in hepatic triacylglycerol content induced by this isomer was not attributable to changes in lipogenesis.

  11. Crystallographic identification of a noncompetitive inhibitor binding site on the hepatitis C virus NS5B RNA polymerase enzyme.

    PubMed

    Love, Robert A; Parge, Hans E; Yu, Xiu; Hickey, Michael J; Diehl, Wade; Gao, Jingjin; Wriggers, Hilary; Ekker, Anne; Wang, Liann; Thomson, James A; Dragovich, Peter S; Fuhrman, Shella A

    2003-07-01

    The virus-encoded nonstructural protein 5B (NS5B) of hepatitis C virus (HCV) is an RNA-dependent RNA polymerase and is absolutely required for replication of the virus. NS5B exhibits significant differences from cellular polymerases and therefore has become an attractive target for anti-HCV therapy. Using a high-throughput screen, we discovered a novel NS5B inhibitor that binds to the enzyme noncompetitively with respect to nucleotide substrates. Here we report the crystal structure of NS5B complexed with this small molecule inhibitor. Unexpectedly, the inhibitor is bound within a narrow cleft on the protein's surface in the "thumb" domain, about 30 A from the enzyme's catalytic center. The interaction between this inhibitor and NS5B occurs without dramatic changes to the structure of the protein, and sequence analysis suggests that the binding site is conserved across known HCV genotypes. Possible mechanisms of inhibition include perturbation of protein dynamics, interference with RNA binding, and disruption of enzyme oligomerization.

  12. Carbonated soft drinks alter hepatic cytochrome P450 isoform expression in Wistar rats.

    PubMed

    Alkhedaide, Adel; Soliman, Mohamed Mohamed; Ibrahim, Zein Shaban

    2016-11-01

    The aim of the current study was to examine the effects of chronic consumption of soft drinks (SDs) on hepatic oxidative stress and cytochrome P450 enzymes (CYPs) expression in the livers of Wistar rats. For 3 consecutive months, the rats had free access to three different soft drinks, Coca-Cola, Pepsi-Cola and 7-UP. The rats were subsequently compared with control group rats that had consumed water. Blood and hepatic tissue samples were assayed for the changes in antioxidants, liver function biomarkers and hepatic gene expression for different isoforms of hepatic CYP. The results indicated that SD consumption (SDC) decreased serum antioxidant levels and increased malondialdehyde secretion, and increased liver biomarkers (glutamate pyruvate transaminase and glutamate oxaloacetate). SD induced alterations in mRNA expression of hepatic antioxidants and cytochrome isoforms. The expression of peroxidase, catalase, CYP1A2, CYP3A2 and CYP2C11 in the liver were upregulated following SDC. By contrast, CYP2B1 was downregulated after 3 months of SDC in liver tissue samples. Thus, the present findings indicate that SDs induced oxidative stress in the liver of Wistar rats and for the first time, to the best of our knowledge, indicate that SDC disrupts hepatic CYP enzymes that may affect drug metabolism. Therefore, drug-dosing programs should be carefully designed to take these novel findings into consideration for the treatment of diseases.

  13. Carbonated soft drinks alter hepatic cytochrome P450 isoform expression in Wistar rats

    PubMed Central

    Alkhedaide, Adel; Soliman, Mohamed Mohamed; Ibrahim, Zein Shaban

    2016-01-01

    The aim of the current study was to examine the effects of chronic consumption of soft drinks (SDs) on hepatic oxidative stress and cytochrome P450 enzymes (CYPs) expression in the livers of Wistar rats. For 3 consecutive months, the rats had free access to three different soft drinks, Coca-Cola, Pepsi-Cola and 7-UP. The rats were subsequently compared with control group rats that had consumed water. Blood and hepatic tissue samples were assayed for the changes in antioxidants, liver function biomarkers and hepatic gene expression for different isoforms of hepatic CYP. The results indicated that SD consumption (SDC) decreased serum antioxidant levels and increased malondialdehyde secretion, and increased liver biomarkers (glutamate pyruvate transaminase and glutamate oxaloacetate). SD induced alterations in mRNA expression of hepatic antioxidants and cytochrome isoforms. The expression of peroxidase, catalase, CYP1A2, CYP3A2 and CYP2C11 in the liver were upregulated following SDC. By contrast, CYP2B1 was downregulated after 3 months of SDC in liver tissue samples. Thus, the present findings indicate that SDs induced oxidative stress in the liver of Wistar rats and for the first time, to the best of our knowledge, indicate that SDC disrupts hepatic CYP enzymes that may affect drug metabolism. Therefore, drug-dosing programs should be carefully designed to take these novel findings into consideration for the treatment of diseases. PMID:27882225

  14. Effects of dietary retinyl acetate on the promotion of hepatic enzyme-altered foci by polybrominated biphenyls in initiated rats.

    PubMed

    Rezabek, M S; Sleight, S D; Jensen, R K; Aust, S D

    1989-08-01

    Vitamin A inhibits the development of some chemically-induced tumours. Since polybrominated biphenyls (PBBs) are hepatic tumour promoters and they affect vitamin A homeostasis in rats, we put forward the hypothesis that dietary levels of vitamin A would influence tumour promotion by PBBs. In the study described here, female Sprague-Dawley rats were initiated on day 1 by ip administration of diethylnitrosamine. On day 7 after initiation, the rats were fed a vitamin A-deficient basal diet that was supplemented with either 2000 IU (low-vitamin A) or 200,000 IU (high-vitamin A) retinyl acetate/kg feed. From day 30 after initiation until the end of the study the following PBBs were added to the diets: Firemaster BP-6 (10 ppm), 2,4,5,2',4',5'-hexabromobiphenyl (10 ppm) or 3,4,5,3',4',5'-hexabromobiphenyl (1 ppm). The control animals received low- or high-vitamin A diets containing no PBBs. On day 180, the rats were necropsied, sections of various tissues were stained for histopathological examination and an evaluation of hepatic enzyme-altered foci was performed. Numbers of gamma-glutamyl transpeptidase-positive foci/cm3 liver and the mean volumes of these foci were lower in the high-vitamin A groups than those in the corresponding low-vitamin A groups, but these differences were not significant. The percentage of the liver volume occupied by foci was significantly greater in the low-vitamin A with 345-HBB group than in the corresponding high-vitamin A group. Thus, high dietary levels of vitamin A had some inhibitory effect on the promotion of hepatic-altered foci by 345-HBB in initiated rats.

  15. Effect of Antiviral Therapy on Serum Activity of Angiotensin Converting Enzyme in Patients with Chronic Hepatitis C

    PubMed Central

    Husic-Selimovic, Azra; Sofic, Amela; Huskic, Jasminko; Bulja, Deniz

    2016-01-01

    Introduction: Renin-angiotenzin system (RAS) is frequently activated in patients with chronic liver disease. Angiotenzin - II (AT-II), produced by angiotenzin converting enzyme (ACE), has many physiological effects, including an important role in liver fibrogenesis. Combined antiviral therapy with PEG-IFN and ribavirin besides its antiviral effect also leads to a reduction in liver parenchyma fibrosis. Aim of the study: Determining the value of ACE in serum of patients with chronic hepatitis C before and after combined antiviral therapy, as well as the value of ACE activities in sera of the control group. Materials and methods: We studied 50 patients treated at Gastroenterohepatology Department, in the time-period of four years. Value of ACE in serum was determined by Olympus AU 400 device, with application of kit “Infinity TN ACE Liquid Stable Reagent”. HCV RNA levels in sera were measured by real time PCR. HCV RNA test was performed with modular analysis of AMPLICOR and COBAS AMPLICOR HCV MONITOR test v2.0, which has proved infection and was used for quantification of the viruses and monitoring of the patients’ response to therapy. Liver histology was evaluated in accordance with the level of necroinflammation activity and stage of fibrosis. Results: Serum activities of ACE in chronic hepatitis C patients is statistically higher than the values in the control group (p=0.02). Antiviral therapy in chronic hepatitis C patients statistically decreases serum activities of ACE (p= 0.02) and indirectly affects fibrogenesis of the liver parenchyma. Correlation between ACE and ALT activity after the therapy was proved (0.3934). Conclusion: Our findings suggest that the activity of ACE in serum is a good indirect parameter of the liver damage, and could be used as an indirect prognostic factor of the level of liver parenchyma damage. Serum activity of ACE can be used as a parameter for non-invasive assessment of intensity of liver damage. PMID:27147779

  16. Autophagy in hepatic fibrosis.

    PubMed

    Song, Yang; Zhao, Yingying; Wang, Fei; Tao, Lichan; Xiao, Junjie; Yang, Changqing

    2014-01-01

    Hepatic fibrosis is a leading cause of morbidity and mortality worldwide. Hepatic fibrosis is usually associated with chronic liver diseases caused by infection, drugs, metabolic disorders, or autoimmune imbalances. Effective clinical therapies are still lacking. Autophagy is a cellular process that degrades damaged organelles or protein aggregation, which participates in many pathological processes including liver diseases. Autophagy participates in hepatic fibrosis by activating hepatic stellate cells and may participate as well through influencing other fibrogenic cells. Besides that, autophagy can induce some liver diseases to develop while it may play a protective role in hepatocellular abnormal aggregates related liver diseases and reduces fibrosis. With a better understanding of the potential effects of autophagy on hepatic fibrosis, targeting autophagy might be a novel therapeutic strategy for hepatic fibrosis in the near future.

  17. Physical properties, lipid composition and enzyme activities of hepatic subcellular membranes from chick embryo after ethanol treatment

    SciTech Connect

    Sanchez-Amate, M.C.; Marco, C.; Segovia, J.L. )

    1992-01-01

    Exposure of chick embryos to ethanol resulted in significant alterations to the lipid composition of various different hepatic subcellular membranes. A marked decrease in cholesterol levels and an increase in the phospholipid content of microsomes and mitochondria was observed. Ethanol also affected the fatty acid profiles, mainly by decreasing the percentage of oleic acid in phosphatidylcholine and phosphatidylethanolamine in the mitochondria and phosphatidylethanolamine in the microsomes. In spite of these changes ethanol only induced alterations in the fluidity of the mitochondrial membranes, which showed a more rigid core, in contrast to the phospholipid-head region, which was not affected. In accordance with the changes observed in the physical state of the membrane, the enzymes involved in the microsomal electron-transport systems were not modified by ethanol, while cytochrome oxidase activity decreased by 50% compared to the activity in the mitochondria from control chick embryos.

  18. Hepatic effects of phthalate esters.

    PubMed Central

    Seth, P K

    1982-01-01

    Di(2-ethylhexyl) phthalate (DEHP), a commonly used plasticizer and microchemical environmental pollutant, produces subtle changes in hepatic function as judged by increase in liver weight and morphological and biochemical alterations. It can modify the biological response of drugs and other xenobiotics. Such interactions appear to occur at the pharmacokinetic phase, as DEHP was found to alter the activity of microsomal drug-metabolizing enzymes and ethanol metabolism. DEHP produced a time- and route-dependent effect on the hepatic cytochrome P-450 contents and activity of aminopyrine N-demethylase, aniline hydroxylase, alcohol dehydrogenase and high and low Km aldehyde dehydrogenases when given orally or intraperitoneally. Under in vitro conditions, DEHP produced no effect on the activity of aminopyrine N-demethylase or aniline hydroxylase, while mono(2-ethylhexyl) phthalate (MEHP) and 2-ethylhexanol (2-EH) significantly inhibited their activity at concentrations ranging from 2.5 to 15.0 mM. Activity of aminopyrine N-demethylase and aniline hydroxylase was also inhibited by dimethyl phthalate (DMP) and dibutyl phthalate (DBP) after a single oral administration. In view of the possibility of the human exposure to phthalates and other xenobiotics simultaneously, these observations are of great significance. PMID:6754361

  19. Venlafaxine pharmacokinetics focused on drug metabolism and potential biomarkers.

    PubMed

    Magalhães, Paulo; Alves, Gilberto; Llerena, Adrián; Falcão, Amílcar

    2014-01-01

    Venlafaxine (VEN) is one of the safest and most effective drugs used in the treatment of selective serotonin reuptake inhibitors-resistant depression, and thereby it is nowadays one of the most commonly prescribed antidepressants. Nevertheless, patients treated with antidepressant drugs including VEN have exhibited large inter-individual variability in drug outcomes, possibly due to the influence of genetic and nongenetic factors on the drug pharmacokinetics and/or pharmacodynamics. Among them, an increased interest has emerged over the last few years on the genetic and/or phenotypic profile for drug-metabolizing cytochrome P450 isoenzymes and drug transporters such as potential predictive pharmacokinetic-based biomarkers of the variability found in drug biodisposition and antidepressant response. The integration of some of these key therapeutic biomarkers with classic therapeutic drug monitoring constitutes a promising way to individualization of VEN's pharmacotherapy, offering to clinicians the ability to better predict and manage pharmacological treatments to maximize the drug effectiveness. Thus, this review provides an extensive discussion of the pharmacokinetics of VEN focusing in particular on metabolism issues, without forgetting the clinically relevant sources of pharmacokinetics variability (mainly the genetic sources) and aiming on the identification of phenotypic and/or genetic biomarkers for therapy optimization.

  20. Effects of neonatally administered chlorpromazine and reserpine on the responsiveness of rat hepatic drug-metabolising enzymes to testosterone in adult life.

    PubMed

    Finnen, M J; Hassall, K A

    1986-01-01

    The effects of neonatally administered chlorpromazine and reserpine on the response of rat hepatic drug-metabolising enzymes to testosterone in adult life have been investigated using the chlorinated cyclodiene substrate DME. Neonatal treatment with chlorpromazine and reserpine had effects on the metabolism of DME similar to, but not as pronounced as, those of castration when adult. The effects of adult castration of male rats on hepatic microsomal metabolism of DME were fully reversed by treatment with testosterone propionate, with metabolism being restored to that of a control intact male. However, testosterone propionate treatment of either intact or castrated adult males that had received neonatal reserpine or chlorpromazine did not restore levels of metabolism to those characteristic of control adult male rats. These results suggest that neonatally administered chlorpromazine and reserpine alter the sensitivity of hepatic drug-metabolising enzymes to the actions of testosterone in adult life.

  1. Antidiabetic efficacy of citronellol, a citrus monoterpene by ameliorating the hepatic key enzymes of carbohydrate metabolism in streptozotocin-induced diabetic rats.

    PubMed

    Srinivasan, Subramani; Muruganathan, Udaiyar

    2016-04-25

    Diabetes mellitus is a clinically complex disease characterized by chronic hyperglycemia with metabolic disturbances. During diabetes, endogenous hepatic glucose production is increased as a result of impaired activities of the key enzymes of carbohydrate metabolism. The purpose of the present study was to evaluate the antidiabetic efficacy of citronellol, a citrus monoterpene in streptozotocin (STZ)-induced diabetic rats. Diabetes mellitus was induced by a single intraperitoneal injection of STZ (40 mg/kg b.w). STZ induced diabetic rats received citronellol orally at the doses of 25, 50, and 100 mg/kg b.w for 30 days. In this study the levels of plasma glucose, insulin, hemoglobin (Hb), glycated hemoglobin (HbA1C), glycogen, and the activities of carbohydrate metabolic enzymes, liver and kidney markers were evaluated. Oral administration of citronellol (50 mg/kg) for 30 days dose dependently improved the levels of insulin, Hb and hepatic glycogen with significant decrease in glucose and HbA1C levels. The altered activities of carbohydrate metabolic enzymes, hepatic and kidney markers were restored to near normal. Citronellol supplement was found to be effective in preserving the normal histological appearance of hepatic cells and insulin-positive β-cells in STZ-rats. Our results suggest that administration of citronellol attenuates the hyperglycemia in the STZ-induced diabetic rats by ameliorating the key carbohydrate metabolic enzymes and could be developed as a functional and nutraceutical ingredient in combating diabetes mellitus.

  2. Hepatic Xenobiotic Metabolizing Enzyme Gene Expression Through the Life Stages of the Mouse

    EPA Science Inventory

    BACKGROUND: Differences in responses to environmental chemicals and drugs between life stages are likely due in part to differences in the expression of xenobiotic metabolizing enzymes and transporters (XMETs). No comprehensive analysis of the mRNA expression of XMETs has been ca...

  3. Effect of selenium-containing compounds on hepatic chemoprotective enzymes in mice.

    PubMed

    El-Sayed, Wael M; Aboul-Fadl, Tarek; Lamb, John G; Roberts, Jeanette C; Franklin, Michael R

    2006-03-15

    Selenite and organoselenium compounds have been examined at supranutritional levels for their ability to influence the activity and mRNA levels of chemoprotective enzymes in the livers of selenium-sufficient mice and the changes compared to those elicited by oltipraz. Compounds investigated included novel selenocysteine prodrugs that have previously been evaluated for their ability to reduce the tumorigenicity of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in mice. Following seven daily doses (i.g.), all compounds except 2-methylselenazolidine-4(R)-carboxylic acid (MSCA) increased thioredoxin reductase activity (43-92%) but only for 2-oxoselenazolidine-4(R)-carboxylic acid (OSCA) was there an accompanying increase in mRNA. No compound enhanced glutathione peroxidase activity, although sodium selenite significantly elevated the mRNA of this enzyme. Oltipraz was an efficacious inducer of both thioredoxin reductase and glutathione peroxidase mRNAs. Sodium selenite, selenazolidine-4(R)-carboxylic acid (SCA), and OSCA elevated NAD(P)H-quinone oxidoreductase mRNA but only for OSCA was the elevation in mRNA accompanied by an increase in enzyme activity. L-Selenocystine significantly increased this activity without increasing mRNA levels. Sodium selenite, L-selenocystine, L-selenomethionine, and Se-methyl-L-selenocysteine all enhanced glutathione S-transferase activity. The increased activity with sodium selenite was accompanied by increases in mRNAs of Gst alpha, Gst mu and Gst pi classes, while for L-selenocystine and Se-methyl-L-selenocysteine, only an elevation in the mRNA for the Gst alpha class was observed. Gst alpha and Gst mu class mRNAs were elevated by OSCA without a significant elevation in enzyme activity. SCA and MSCA both elevated a Gst pi mRNA and MSCA elevated Gst mu in addition. By comparison, oltipraz only significantly elevated the mRNA of Gst mu, adding to the conclusion that across the entire study, no selenium compound appears to be acting

  4. Influence of Piper betle on hepatic marker enzymes and tissue antioxidant status in D-galactosamine-induced hepatotoxic rats.

    PubMed

    Pushpavalli, Ganesan; Veeramani, Chinnadurai; Pugalendi, Kodukkur Viswanathan

    2008-01-01

    D-galactosamine is a well-established hepatotoxicant that induces a diffuse type of liver injury closely resembling human viral hepatitis. D-galactosamine by its property of generating free radicals causes severe damage to the membrane and affects almost all organs of the human body. The leaves of Piper betle L., a commonly used masticatory in Asian countries, possess several biological properties. Our aim is to investigate the in vivo antioxidant potential of P. betle leaf-extract against oxidative stress induced by D-galactosamine intoxication in male albino Wistar rats. Toxicity was induced by an intraperitoneal injection of D-galactosamine, 400 mg/kg body weight (BW) for 21 days. Rats were treated with P. betle extract (200 mg/kg BW) via intragastric intubations. We assessed the activities of liver marker enzymes (aspartate amino-transferase, alanine aminotransferase, alkaline phosphatase, gamma glutamyl transpeptidase) and levels of thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides, superoxide dismutase, catalase, glutathione peroxidase, vitamin C, vitamin E, and reduced glutathione. The extract significantly improved the status of antioxidants and decreased TBARS, hydroperoxides, and liver marker enzymes when compared with the D-galactosamine treated group, demonstrating its hepatoprotective and antioxidant properties.

  5. Influence of Piper betle on hepatic marker enzymes and tissue antioxidant status in ethanol-treated Wistar rats.

    PubMed

    Saravanan, R; Prakasam, A; Ramesh, B; Pugalendi, K V

    2002-01-01

    Piper betle L. is a commonly used masticatory in Asia. This study was carried out to investigate the hepatoprotective and antioxidant properties of P. betle, using ethanol intoxication as a model of hepatotoxic and oxidative damage. Ethanol-treated rats exhibited elevation of hepatic marker enzymes and disturbances in antioxidant defense when compared with normal rats. Oral administration of P. betle extract (100, 200, or 300 mg/kg body weight) for 30 days significantly (P <.05) decreased aspartate aminotransferase (AST), alanine aminotransferase (ALT), thiobarbituric acid reactive substances (TBARS), and lipid hydroperoxides in ethanol treated rats. The extract also improved the tissue antioxidant status by increasing the levels of nonenzymatic antioxidants (reduced glutathione, vitamin C, and vitamin E) and the activities of free radical-detoxifying enzymes such as superoxide dismutase, catalase, and glutathione peroxidase in liver and kidney of ethanol-treated rats. The highest dose of P. betle extract (300 mg/kg body weight) was most effective. The results were comparable with the known hepatoprotective drug, silymarin. These results indicate that P. betle could afford a significant hepatoprotective and antioxidant effect.

  6. Characterization of human hepatic and extrahepatic UDP-glucuronosyltransferase enzymes involved in the metabolism of classic cannabinoids.

    PubMed

    Mazur, Anna; Lichti, Cheryl F; Prather, Paul L; Zielinska, Agnieszka K; Bratton, Stacie M; Gallus-Zawada, Anna; Finel, Moshe; Miller, Grover P; Radomińska-Pandya, Anna; Moran, Jeffery H

    2009-07-01

    Tetrahydrocannabinol (Delta(9)-THC), the primary psychoactive ingredient in marijuana, is subject to cytochrome P450 oxidation and subsequent UDP-glucuronosyltransferase (UGT)-dependent glucuronidation. Many studies have shown that CYP2C9 and CYP3A4 are the primary enzymes responsible for these cytochrome P450-dependent oxidations, but little work has been done to characterize phase II metabolic pathways. In this study, we test the hypothesis that there are specific human UGTs responsible for classic cannabinoid metabolism. The activities of 12 human recombinant UGTs toward classic cannabinoids [cannabinol (CBN), cannabidiol (CBD), (-)-Delta(8)-THC, (-)-Delta(9)-THC, (+/-)-11-hydroxy-Delta(9)-THC (THC-OH), and (-)-11-nor-9-carboxy-Delta(9)-THC (THC-COOH)] were evaluated using high-performance liquid chromatography-tandem mass spectrometry and labeling assays. Despite activity by UGT1A1, 1A3, 1A8, 1A9, 1A10, and 2B7 toward CBN, CBD, THC-OH, and THC-COOH, only selected UGTs demonstrate sufficient activity for further characterization of steady-state kinetics. CBN was the most recognized substrate as evidenced by activities from hepatic UGT1A9 and extrahepatic UGT1A7, UGT1A8, and UGT1A10. These results may reflect the introduction of an aromatic ring to Delta(9)-THC, leading to favorable pi stacking with phenylalanines in the UGT active site. Likewise, oxidation of Delta(9)-THC to THC-OH results in UGT1A9 and UGT1A10 activity toward the cannabinoid. Further oxidation to THC-COOH surprisingly leads to a loss in metabolism by UGT1A9 and UGT1A10, while creating a substrate recognized by UGT1A1 and UGT1A3. The resulting glucuronide of THC-COOH is the main metabolite found in urine, and thus these hepatic enzymes play a critical role in the metabolic clearance of cannabinoids. Taken together, glucuronidation of cannabinoids depends on upstream processing including enzymes such as CYP2C9 and CYP3A4.

  7. Characterization of Human Hepatic and Extrahepatic UDP-Glucuronosyltransferase Enzymes Involved in the Metabolism of Classic Cannabinoids

    PubMed Central

    Mazur, Anna; Lichti, Cheryl F.; Prather, Paul L.; Zielinska, Agnieszka K.; Bratton, Stacie M.; Gallus-Zawada, Anna; Finel, Moshe; Miller, Grover P.; Radomińska-Pandya, Anna; Moran, Jeffery H.

    2009-01-01

    Tetrahydrocannabinol (Δ9-THC), the primary psychoactive ingredient in marijuana, is subject to cytochrome P450 oxidation and subsequent UDP-glucuronosyltransferase (UGT)-dependent glucuronidation. Many studies have shown that CYP2C9 and CYP3A4 are the primary enzymes responsible for these cytochrome P450-dependent oxidations, but little work has been done to characterize phase II metabolic pathways. In this study, we test the hypothesis that there are specific human UGTs responsible for classic cannabinoid metabolism. The activities of 12 human recombinant UGTs toward classic cannabinoids [cannabinol (CBN), cannabidiol (CBD), (–)-Δ8-THC, (–)-Δ9-THC, (±)-11-hydroxy-Δ9-THC (THC-OH), and (–)-11-nor-9-carboxy-Δ9-THC (THC-COOH)] were evaluated using high-performance liquid chromatography-tandem mass spectrometry and labeling assays. Despite activity by UGT1A1, 1A3, 1A8, 1A9, 1A10, and 2B7 toward CBN, CBD, THC-OH, and THC-COOH, only selected UGTs demonstrate sufficient activity for further characterization of steady-state kinetics. CBN was the most recognized substrate as evidenced by activities from hepatic UGT1A9 and extrahepatic UGT1A7, UGT1A8, and UGT1A10. These results may reflect the introduction of an aromatic ring to Δ9-THC, leading to favorable π stacking with phenylalanines in the UGT active site. Likewise, oxidation of Δ9-THC to THC-OH results in UGT1A9 and UGT1A10 activity toward the cannabinoid. Further oxidation to THC-COOH surprisingly leads to a loss in metabolism by UGT1A9 and UGT1A10, while creating a substrate recognized by UGT1A1 and UGT1A3. The resulting glucuronide of THC-COOH is the main metabolite found in urine, and thus these hepatic enzymes play a critical role in the metabolic clearance of cannabinoids. Taken together, glucuronidation of cannabinoids depends on upstream processing including enzymes such as CYP2C9 and CYP3A4. PMID:19339377

  8. In Vitro Evaluation of the Effects of Eurycoma longifolia Extract on CYP-Mediated Drug Metabolism.

    PubMed

    Han, Young Min; Kim, In Sook; Rehman, Shaheed Ur; Choe, Kevin; Yoo, Hye Hyun

    2015-01-01

    Eurycoma longifolia (Simaroubaceae) is a popular folk medicine that has traditionally been used in Southeast Asia as an antimalarial, aphrodisiac, antidiabetic, and antimicrobial and in antipyretic remedies. This study evaluates the effects of Eurycoma longifolia extract on cytochrome P450 (CYP) enzyme-mediated drug metabolism to predict the potential for herb-drug interactions. Methanolic extract of E. longifolia root was tested at concentrations of 1, 3, 10, 30, 100, 300, and 1000 µg/mL in human liver microsomes or individual recombinant CYP isozymes. The CYP inhibitory activity was measured using the cocktail probe assay based on liquid chromatography-tandem mass spectrometry. E. longifolia showed weak, concentration-dependent inhibition of CYP1A2, CYP2A6, and CYP2C19. The inhibitory effects on these CYP isozymes were further tested using individual recombinant CYP isozymes, showing IC50 values of 324.9, 797.1, and 562.9 μg/mL, respectively. In conclusion, E. longifolia slightly inhibited the metabolic activities of CYP1A2, CYP2A6, and CYP2C19 but this issue requires careful attention in taking herbal medicines or dietary supplements containing E. longifolia extracts.

  9. In Vitro Evaluation of the Effects of Eurycoma longifolia Extract on CYP-Mediated Drug Metabolism

    PubMed Central

    Han, Young Min; Kim, In Sook; Rehman, Shaheed Ur; Choe, Kevin; Yoo, Hye Hyun

    2015-01-01

    Eurycoma longifolia (Simaroubaceae) is a popular folk medicine that has traditionally been used in Southeast Asia as an antimalarial, aphrodisiac, antidiabetic, and antimicrobial and in antipyretic remedies. This study evaluates the effects of Eurycoma longifolia extract on cytochrome P450 (CYP) enzyme-mediated drug metabolism to predict the potential for herb-drug interactions. Methanolic extract of E. longifolia root was tested at concentrations of 1, 3, 10, 30, 100, 300, and 1000 µg/mL in human liver microsomes or individual recombinant CYP isozymes. The CYP inhibitory activity was measured using the cocktail probe assay based on liquid chromatography-tandem mass spectrometry. E. longifolia showed weak, concentration-dependent inhibition of CYP1A2, CYP2A6, and CYP2C19. The inhibitory effects on these CYP isozymes were further tested using individual recombinant CYP isozymes, showing IC50 values of 324.9, 797.1, and 562.9 μg/mL, respectively. In conclusion, E. longifolia slightly inhibited the metabolic activities of CYP1A2, CYP2A6, and CYP2C19 but this issue requires careful attention in taking herbal medicines or dietary supplements containing E. longifolia extracts. PMID:26240600

  10. Mammalian flavin-containing monooxygenases: structure/function, genetic polymorphisms and role in drug metabolism

    PubMed Central

    Krueger, Sharon K.; Williams, David E.

    2005-01-01

    Flavin-containing monooxygenase (FMO) oxygenates drugs and xenobiotics containing a “soft-nucleophile”, usually nitrogen or sulfur. FMO, like cytochrome P450 (CYP), is a monooxygenase, utilizing the reducing equivalents of NADPH to reduce 1 atom of molecular oxygen to water, while the other atom is used to oxidize the substrate. FMO and CYP also exhibit similar tissue and cellular location, molecular weight, substrate specificity, and exist as multiple enzymes under developmental control. The human FMO functional gene family is much smaller (5 families each with a single member) than CYP. FMO does not require a reductase to transfer electrons from NADPH and the catalytic cycle of the 2 monooxygenases is strikingly different. Another distinction is the lack of induction of FMOs by xenobiotics. In general, CYP is the major contributor to oxidative xenobiotic metabolism. However, FMO activity may be of significance in a number of cases and should not be overlooked. FMO and CYP have overlapping substrate specificities, but often yield distinct metabolites with potentially significant toxicological/pharmacological consequences. The physiological function(s) of FMO are poorly understood. Three of the 5 expressed human FMO genes, FMO1, FMO2 and FMO3, exhibit genetic polymorphisms. The most studied of these is FMO3 (adult human liver) in which mutant alleles contribute to the disease known as trimethylaminuria. The consequences of these FMO genetic polymorphisms in drug metabolism and human health are areas of research requiring further exploration. PMID:15922018

  11. Kinetics of conjugation and oxidation of nitrobenzyl alcohols by rat hepatic enzymes.

    PubMed

    Rickert, D E; deBethizy, J D; Glover, M R; Kedderis, G L

    1985-12-01

    Previous work has suggested that quantitative differences in the in vitro and in vivo metabolism of mononitrotoluene isomers are a result of differences in the hepatic conjugation and oxidation of the first metabolic intermediates, the mononitrobenzyl alcohols. We have determined the steady-state kinetic parameters, Vmax, Km and V/K, for the metabolism of the nitrobenzyl alcohols by rat hepatic alcohol dehydrogenase, glucuronyltransferase, and sulfotransferase. 3-Nitrobenzyl alcohol was the best substrate for cytosolic alcohol dehydrogenase (Vmax = 1.48 nmoles/min/mg protein, V/K = 3.15 X 10(-3) nmoles/min/mg protein/microM, Km = 503 microM). Vmax and Km values for 4-nitrobenzyl alcohol were similar, but V/K was about 60% of that for 3-nitrobenzyl alcohol. 2-Nitrobenzyl alcohol was not metabolized by the alcohol dehydrogenase preparation used here, but it was metabolized to 2-nitrobenzoic acid by a rat liver mitochondrial preparation. 2-Nitrobenzyl alcohol was the best substrate for microsomal glucuronyltransferase (Vmax = 3.59 nmoles/min/mg protein, V/K = 11.28 X 10(-3) nmoles/min/mg protein/microM, Km = 373 microM). The Vmax for 3-nitrobenzyl alcohol was similar, but the V/K was about half and the Km was about twice that for 2-nitrobenzyl alcohol. The Vmax for 4-nitrobenzyl alcohol was about 40% and the V/K was about half that for 2-nitrobenzyl alcohol. The best substrate for cytosolic sulfotransferase was 4-nitrobenzyl alcohol (Vmax = 1.69 nmoles/min/mg protein, V/K = 37.21 X 10(-3) nmoles/min/mg protein/microM, Km = 48 microM). The Vmax values for the other two benzyl alcohols were similar, but the V/K and Km values were about 11 and 400%, respectively, of those for 4-nitrobenzyl alcohol. These data are in qualitative agreement with results obtained when the nitrobenzyl alcohols were incubated with isolated hepatocytes, but they do not allow quantitative modeling of the data from hepatocytes.

  12. Development of a Highly Sensitive Bioluminescent Enzyme Immunoassay for Hepatitis B Virus Surface Antigen Capable of Detecting Divergent Mutants

    PubMed Central

    Takehara, Shizuka; Takahashi, Masaharu

    2013-01-01

    Hepatitis B virus (HBV) infections are sometimes overlooked when using commercial kits to measure hepatitis B virus surface antigen (HBsAg) due to their low sensitivities and reactivities to mutant strains of various genotypes. We developed an ultrasensitive bioluminescent enzyme immunoassay (BLEIA) for HBsAg using firefly luciferase, which is adaptable to a variety of HBsAg mutants, by combining four monoclonal antibodies with a polyclonal antibody against HBsAg. The measurement of seroconversion panels showed trace amounts of HBsAg during the early infection phase by the BLEIA because of its high sensitivity of 5 mIU/ml. The BLEIA detected HBsAg as early as did PCR in five of seven series and from 2.1 to 9.4 days earlier than commercial immunoassay methods. During the late infection phase, the BLEIA successfully detected HBsAg even 40 days after the disappearance of HBV DNA and the emergence of antibodies against HBsAg. The HBsAg BLEIA successfully detected all 13 recombinant HBsAg and 45 types of HBsAg mutants with various mutations within amino acids 90 to 164 in the S gene product. Some specimens had higher values determined by the BLEIA than those by a commercial chemiluminescent immunoassay; this suggests that such discrepancies were caused by the dissociation of preS1/preS2 peptides from the particle surface. With its highly sensitive detection of low-titer HBsAg, including various mutants, the HBsAg BLEIA is considered to be useful for the early diagnosis and prevention of HBV infection because of the shorter window of infection prior to detection, which facilitates early prediction of recurrence in HBV-infected individuals. PMID:23761660

  13. Gene expression profiling in male B6C3F1 mouse livers exposed to kava identifies--changes in drug metabolizing genes and potential mechanisms linked to kava toxicity.

    PubMed

    Guo, Lei; Shi, Qiang; Dial, Stacey; Xia, Qingsu; Mei, Nan; Li, Quan-zhen; Chan, Po-Chuen; Fu, Peter

    2010-02-01

    The association of kava products with liver-related health risks has prompted regulatory action in many countries. We used a genome-wide gene expression approach to generate global gene expression profiles from the livers of male B6C3F1 mice administered kava extract by gavage for 14 weeks, and identified the differentially expressed drug metabolizing genes in response to kava treatments. Analyses of gene functions and pathways reveal that the levels of significant numbers of genes involving drug metabolism were changed and that the pathways involving xenobiotics metabolism, Nrf2-mediated oxidative stress response, mitochondrial functions and others, were altered. Our results indicate that kava extract can significantly modulate drug metabolizing enzymes, potentially leading to herb-drug interactions and hepatotoxicity.

  14. Comparative toxicology of tetrachlorobiphenyls in mink and rats. I. Changes in hepatic enzyme activity and smooth endoplasmic reticulum volume

    SciTech Connect

    Gillette, D.M.; Corey, R.D.; Helferich, W.G.; McFarland, J.M.; Lowenstine, L.J.; Moody, D.E.; Hammock, B.D.; Shull, L.R.

    1987-01-01

    Mink have been shown previously to be extraordinarily sensitive to polychlorinated biphenyls (PCBs) and related classes of halogenated hydrocarbons. This study explored several aspects of the acute response of mink to two purified tetrachlorobiphenyl (TCB) congeners and compared their response with that of the rat, a less sensitive and more thoroughly studied species. Young female pastel mink and young female Sprague-Dawley rats received three daily intraperitoneal injections with equimolar doses of either 2,4,2',4'-TCB or 3,4,3',4'-TCB, and were sacrificed after 7 days. Two control groups were used for each species; one was allowed free access to food and the other was pair-fed to the 3,4,3',4'-TCB treatment group. Rats remained clinically normal, while mink treated with 3,4,3',4'-TCB developed severe anorexia, diarrhea, and melena. Both species had significant increases in hepatic cytochrome P-450 content and the characteristic shift in the spectral maxima from 450 to 448 nm in the 3,4,3',4'-TCB- but not in the 2,4,2',4'-TCB-treated animals. Rats but not mink had increased activities of several hepatic monooxygenases in response to both congeners while microsomal epoxide hydrolase was increased in rats after 2,4,2',4'-TCB and in mink after 3,4,3',4'-TCB. Significant increases in the relative volume of smooth endoplasmic reticulum within hepatocytes of 2,4,2',4'-TCB-treated rats but not mink were confirmed by ultrastructural morphometry. Accumulation of both congeners was greater in adipose tissue than in the liver of either species. In both species, concentrations in adipose tissue were much greater for 2,4,2',4'-TCB than for 3,4,3',4'-TCB. PCB toxicosis in mink, as in other species, appeared to be dependent on isomeric arrangement of chlorine substituents. However, unlike other species, the toxicosis was not associated with biochemical or morphological evidence of hepatic enzyme induction.

  15. Hepatic and extrahepatic distribution of ornithine urea cycle enzymes in holocephalan elephant fish (Callorhinchus milii).

    PubMed

    Takagi, Wataru; Kajimura, Makiko; Bell, Justin D; Toop, Tes; Donald, John A; Hyodo, Susumu

    2012-04-01

    Cartilaginous fish comprise two subclasses, the Holocephali (chimaeras) and Elasmobranchii (sharks, skates and rays). Little is known about osmoregulatory mechanisms in holocephalan fishes except that they conduct urea-based osmoregulation, as in elasmobranchs. In the present study, we examined the ornithine urea cycle (OUC) enzymes that play a role in urea biosynthesis in the holocephalan elephant fish, Callorhinchus milii (cm). We obtained a single mRNA encoding carbamoyl phosphate synthetase III (cmCPSIII) and ornithine transcarbamylase (cmOTC), and two mRNAs encoding glutamine synthetases (cmGSs) and two arginases (cmARGs), respectively. The two cmGSs were structurally and functionally separated into two types: brain/liver/kidney-type cmGS1 and muscle-type cmGS2. Furthermore, two alternatively spliced transcripts with different sizes were found for cmgs1 gene. The longer transcript has a putative mitochondrial targeting signal (MTS) and was predominantly expressed in the liver and kidney. MTS was not found in the short form of cmGS1 and cmGS2. A high mRNA expression and enzyme activities were found in the liver and muscle. Furthermore, in various tissues examined, mRNA levels of all the enzymes except cmCPSIII were significantly increased after hatching. The data show that the liver is the important organ for urea biosynthesis in elephant fish, but, extrahepatic tissues such as the kidney and muscle may also contribute to the urea production. In addition to the role of the extrahepatic tissues and nitrogen metabolism, the molecular and functional characteristics of multiple isoforms of GSs and ARGs are discussed.

  16. Arylamine N-acetyltransferases: from drug metabolism and pharmacogenetics to drug discovery

    PubMed Central

    Sim, E; Abuhammad, A; Ryan, A

    2014-01-01

    Arylamine N-acetyltransferases (NATs) are polymorphic drug-metabolizing enzymes, acetylating arylamine carcinogens and drugs including hydralazine and sulphonamides. The slow NAT phenotype increases susceptibility to hydralazine and isoniazid toxicity and to occupational bladder cancer. The two polymorphic human NAT loci show linkage disequilibrium. All mammalian Nat genes have an intronless open reading frame and non-coding exons. The human gene products NAT1 and NAT2 have distinct substrate specificities: NAT2 acetylates hydralazine and human NAT1 acetylates p-aminosalicylate (p-AS) and the folate catabolite para-aminobenzoylglutamate (p-abaglu). Human NAT2 is mainly in liver and gut. Human NAT1 and its murine homologue are in many adult tissues and in early embryos. Human NAT1 is strongly expressed in oestrogen receptor-positive breast cancer and may contribute to folate and acetyl CoA homeostasis. NAT enzymes act through a catalytic triad of Cys, His and Asp with the architecture of the active site-modulating specificity. Polymorphisms may cause unfolded protein. The C-terminus helps bind acetyl CoA and differs among NATs including prokaryotic homologues. NAT in Salmonella typhimurium supports carcinogen activation and NAT in mycobacteria metabolizes isoniazid with polymorphism a minor factor in isoniazid resistance. Importantly, nat is in a gene cluster essential for Mycobacterium tuberculosis survival inside macrophages. NAT inhibitors are a starting point for novel anti-tuberculosis drugs. Human NAT1-specific inhibitors may act in biomarker detection in breast cancer and in cancer therapy. NAT inhibitors for co-administration with 5-aminosalicylate (5-AS) in inflammatory bowel disease has prompted ongoing investigations of azoreductases in gut bacteria which release 5-AS from prodrugs including balsalazide. PMID:24467436

  17. Irreversible enzyme inhibition kinetics and drug-drug interactions.

    PubMed

    Mohutsky, Michael; Hall, Stephen D

    2014-01-01

    This chapter describes the types of irreversible inhibition of drug-metabolizing enzymes and the methods commonly employed to quantify the irreversible inhibition and subsequently predict the extent and time course of clinically important drug-drug interactions.

  18. Gluconeogenic substrates and hepatic gluconeogenic enzymes in streptozotocin-diabetic rats: effect of mulberry (Morus indica L.) leaves.

    PubMed

    Andallu, B; Varadacharyulu, N C

    2007-03-01

    Mulberry (Morus indica L.) leaves, the sole food of the silk worm, were evaluated for antidiabetic effects in streptozotocin (STZ)-diabetic rats. Treatment with dried mulberry leaf powder at 25% of the diet for a period of 8 weeks was found to be remarkably beneficial to STZ-diabetic rats as evidenced by controlled hyperglycemia and glycosuria. In addition, mulberry leaves countered (reversed) the alterations in gluconeogenic substrates in STZ-diabetic rats as indicated by significant reduction in serum pyruvic and lactic acid levels, a significant increase in proteins and a significant decrease in free amino acid, urea, and creatinine levels in blood, and a decreased urinary excretion of urea and creatinine. Anomalies in the activities of hepatic gluconeogenic enzymes associated with impaired glucose homeostasis in STZ-diabetic rats were ameliorated by feeding the mulberry leaf-supplemented diet, indicating that control over hyperglycemia and associated complications in the diabetic state by mulberry leaves is by way of regulation of gluconeogenesis. With respect to all the parameters, mulberry leaves were more effective than the oral hypoglycemic drug glibenclamide.

  19. Rapid and accurate liquid chromatography and tandem mass spectrometry method for the simultaneous quantification of ten metabolic reactions catalyzed by hepatic cytochrome P450 enzymes.

    PubMed

    Shi, Rong; Ma, Bingliang; Wu, Jiasheng; Wang, Tianming; Ma, Yueming

    2015-10-01

    The hepatic cytochrome P450 enzymes play a central role in the biotransformation of endogenous and exogenous substances. A sensitive high-throughput liquid chromatography with tandem mass spectrometry assay was developed and validated for the simultaneous quantification of the products of ten metabolic reactions catalyzed by hepatic cytochrome P450 enzymes. After the substrates were incubated separately, the samples were pooled and analyzed by liquid chromatography with tandem mass spectrometry using an electrospray ionization source in the positive and negative ion modes. The method exhibited linearity over a broad concentration range, insensitivity to matrix effects, and high accuracy, precision, and stability. The novel method was successfully applied to study the kinetics of phenacetin-O deethylation, coumarin-7 hydroxylation, bupropion hydroxylation, taxol-6 hydroxylation, omeprazole-5 hydroxylation, dextromethorphan-O demethylation, tolbutamide-4 hydroxylation, chlorzoxazone-6 hydroxylation, testosterone-6β hydroxylation, and midazolam-1 hydroxylation in rat liver microsomes.

  20. [Drug metabolism in patients with liver disease (author's transl)].

    PubMed

    Richter, E; Epping, J; Fuchshofen-Röckel, M; Heusler, H; Zilly, W

    1980-10-01

    Patients with acute hepatitis and patients with compensated or decompensated cirrhosis of the liver have a decreased plasma clearance of hexobarbital. This however could not been demonstrated in patients with intra- or extrahepatic cholestasis and patients with primary biliary cirrhosis of the liver. The plasma clearance of methohexital, - a high clearance drug - is not changed in the same way. Also there is no evidence as yet, that patients with liver disease and without a collateral portal circulation do have an increased bioavailability of oral high clearance drugs.

  1. Cytochrome P450 genetic polymorphism in neonatal drug metabolism: role and practical consequences towards a new drug culture in neonatology.

    PubMed

    Fanni, D; Ambu, R; Gerosa, C; Nemolato, S; Castagnola, M; Van Eyken, P; Faa, G; Fanos, V

    2014-01-01

    The cytochrome P450 superfamily (CYP450) in humans is formed by 57 functional monooxygenases critical for the metabolism of numerous endogenous and exogenous compounds. The superfamily is organized into 18 families and 44 subfamilies. CYP nomenclature is based on the identity of amino acids. The most important functions of the CYP450 are related to metabolism of endogenous compounds, detoxification of exogenous xenobiotics and decomposition of the vast majority of currently used drugs. The expression of CYP450 enzymes in the human body is characterized by a marked substrate and tissue specificity, the most important being localized in the liver, but also present in kidney, lung, brain, breast, prostate and in the small intestine. The human cytochrome P450 3A gene family (CYP3A) accounts for the largest portion of CYP450 proteins in human liver and includes 4 genes: CYP3A4, CYP3A5, CYP3A7, CYP3A43. Multiple and complex genetic variations, marked interindividual, interethnic and gender variability have been reported regarding CYP3A isoform expression and activity. Multiple factors may affect CYP3A expression and activity, such as inducers like rifampicin, phenobarbital, 3-methylcholantrene, beta-naphtoflavone, and dexamethasone. The maturation of organ systems, paralleled by ontogeny of drug-metabolizing enzymes during fetal life and in the first months of postnatal life, surely exerts profound effects on drug disposition, probably being the predominant factor accounting for age-associated changes in drug clearance. In fact, drug dosage in the perinatal period represents a continuous challenge for neonatologists. The purpose of this article is to provide a brief review of the pharmacokinetic differences between neonates and adults, showing the peculiarities of liver CYP450-related drug metabolism in the perinatal period and at birth, and to report the toxic mechanisms of liver injury in neonates, due to the most frequently utilized drugs in NICU centers.

  2. Piezotronic-effect enhanced drug metabolism and sensing on a single ZnO nanowire surface with the presence of human cytochrome P450.

    PubMed

    Wang, Ning; Gao, Caizhen; Xue, Fei; Han, Yu; Li, Tao; Cao, Xia; Zhang, Xueji; Zhang, Yue; Wang, Zhong Lin

    2015-03-24

    Cytochromes P450 (CYPs) enzymes are involved in catalyzing the metabolism of various endogenous and exogenous compounds. A rapid analysis of drug metabolism reactions by CYPs is required because they can metabolize 95% of current drugs in drug development and effective therapies. Here, we describe a study of piezotronic-effect enhanced drug metabolism and sensing by utilizing a single ZnO nanowire (ZnO NW) device. Owing to the unique hydrophobic feature of a ZnO NW that provides a desirable "microenvironment" for the immobilization of biomolecules, our device can effectively stimulate the tolbutamide metabolism by decorating a ZnO NW with cytochrome P4502C9/CYPs reductase (CYP2C9/CPR) microsomes. By applying an external compressive strain to the ZnO nanowire, the piezotronic effect, which plays a primary role in tuning the transport behavior of a ZnO NW utilizing the created piezoelectric polarization charges at the local interface, can effectively enhance the performance of the device. A theoretical model is proposed using an energy band diagram to explain the experimental data. This study provides a potential approach to study drug metabolism and trace drug detection based on the piezotronic effect.

  3. Cell signalling and the hormonal stimulation of the hepatic glycine cleavage enzyme system by glucagon.

    PubMed Central

    Mabrouk, G M; Jois, M; Brosnan, J T

    1998-01-01

    The glycine cleavage enzyme system (GCS) is found in mitochondria. In liver it is activated by glucagon and other hormones but it is not known how the hormonal signal is transmitted to the mitochondria. We found that the cell-permeant protein phosphatase inhibitor okadaic acid stimulated flux through GCS and could induce a significant increase in the sensitivity of GCS and of glycogenolysis to glucagon. Half-maximal stimulation of GCS by glucagon occurred at 3.2+/-0.6 nM, whereas it was fully activated at 0.3 nM in the presence of 1 microM okadaic acid. The protein kinase A agonist adenosine-3',5'-cyclic monophosphorothioate, Sp isomer (10 microM) stimulated the GCS flux by approx. 100%. This stimulation was inhibited by the protein kinase A antagonist 8-bromoadenosine-3', 5'-cyclic monophosphorothioate, Rp isomer (Rp-8-Br-cAMPS). Although Rp-8-Br-cAMPS significantly inhibited glucagon-stimulated glycogenolysis it had no effect on the glucagon-stimulated GCS flux. These results indicate that a cytoplasmic phosphorylated protein is involved in transmitting glucagon's effect to the mitochondria. However, protein kinase A does not have a necessary role in transmitting glucagon's signal. We also examined the role of protein kinase C because angiotensin II also stimulated flux through GCS. However, the phorbol ester PMA had no effect on either GCS or on glycogenolysis. PMID:9480887

  4. Comparison of constitutive gene expression levels of hepatic cholesterol biosynthetic enzymes between Wistar-Kyoto and stroke-prone spontaneously hypertensive rats.

    PubMed

    Nemoto, Kiyomitsu; Ikeda, Ayaka; Ito, Sei; Miyata, Misaki; Yoshida, Chiaki; Degawa, Masakuni

    2013-01-01

    Serum total cholesterol amounts in the stroke-prone hypertensive rat (SHRSP) strain are lower than in the normotensive control strain, Wistar-Kyoto (WKY) rat. To understand the strain difference, constitutive gene expression levels of hepatic cholesterol biosynthetic enzymes in male 8-week-old SHRSP and WKY rats were comparatively examined by DNA microarray and real-time reverse transcription-polymerase chain reaction (RT-PCR) analyses. Of 22 cholesterol biosynthetic enzyme genes, expression levels of 8 genes, Pmvk, Idi1, Fdps, Fdft1, Sqle, Lss, Sc4mol, and Hsd17b7, in SHRSP were less than 50% those of the WKY rats; especially, the expression level of Sqle gene, encoding squalene epoxidase, a rate-limiting enzyme in cholesterol biosynthesis pathway, was about 20%. The gene expression level of sterol regulatory element-binding protein-2 (SREBP-2), which functions as a transcription factor upregulating gene expression of cholesterol biosynthetic enzymes, in SHRSP was about 70% of that in WKY rats. These results demonstrate the possibility that the lower serum total cholesterol level in SHRSP is defined by lower gene expression of most hepatic cholesterol biosynthetic enzymes. In particular, decreased gene expression level of Sqle gene might be the most essential factor. Moreover, the broad range of lowered rates of these genes in SHRSP suggests that the abnormal function and/or expression not only of SREBP-2 but also of one or more other transcription factors for those gene expressions exist in SHRSP.

  5. The roles of nuclear receptors CAR and PXR in hepatic energy metabolism.

    PubMed

    Konno, Yoshihiro; Negishi, Masahiko; Kodama, Susumu

    2008-01-01

    Nuclear receptors constitutive active/androstane receptor (CAR) and pregnane X receptor (PXR) were originally characterized as transcription factors regulating the hepatic genes that encode drug metabolizing enzymes. Recent works have now revealed that these nuclear receptors also play the critical roles in modulating hepatic energy metabolism. While CAR and PXR directly bind to their response sequences phenobarbital-responsive enhancer module (PBREM) and xenobiotic responsive enhancer module (XREM) in the promoter of target genes to increase drug metabolism, the receptors also cross talk with various hormone responsive transcription factors such as forkhead box O1 (FoxO1), forkhead box A2 (FoxA2), cAMP-response element binding protein, and peroxisome proliferator activated receptor gamma coactivator 1alpha (PGC 1alpha) to decrease energy metabolism through down-regulating gluconeogenesis, fatty acid oxidation and ketogenesis and up-regulating lipogenesis. In addition, CAR modulates thyroid hormone activity by regulating type 1 deiodinase in the regenerating liver. Thus, CAR and PXR are now placed at the crossroad where both xenobiotics and endogenous stimuli co-regulate liver function.

  6. Development of gold-immobilized P450 platform for exploring the effect of oligomer formation on P450-mediated metabolism for in vitro to in vivo drug metabolism predictions

    NASA Astrophysics Data System (ADS)

    Kabulski, Jarod L.

    The cytochrome P450 (P450) enzyme family is responsible for the biotransformation of a wide range of endogenous and xenobiotic compounds, as well as being the major metabolic enzyme in first pass drug metabolism. In vivo drug metabolism for P450 enzymes is predicted using in vitro data obtained from a reconstituted expressed P450 system, but these systems have not always been proven to accurately represent in vivo enzyme kinetics, due to interactions caused by oligomer formation. These in vitro systems use soluble P450 enzymes prone to oligomer formation and studies have shown that increased states of protein aggregation directly affect the P450 enzyme kinetics. We have developed an immobilized enzyme system that isolates the enzyme and can be used to elucidate the effect of P450 aggregation on metabolism kinetics. The long term goal of my research is to develop a tool that will help improve the assessment of pharmaceuticals by better predicting in vivo kinetics in an in vitro system. The central hypothesis of this research is that P450-mediated kinetics measured in vitro is dependent on oligomer formation and that the accurate prediction of in vivo P450-mediated kinetics requires elucidation of the effect of oligomer formation. The rationale is that the development of a P450 bound to a Au platform can be used to control the aggregation of enzymes and bonding to Au may also permit replacement of the natural redox partners with an electrode capable of supplying a constant flow of electrons. This dissertation explains the details of the enzyme attachment, monitoring substrate binding, and metabolism using physiological and electrochemical methods, determination of enzyme kinetics, and the development of an immobilized-P450 enzyme bioreactor. This work provides alternative approaches to studying P450-mediated kinetics, a platform for controlling enzyme aggregation, electrochemically-driven P450 metabolism, and for investigating the effect of protein

  7. Update Information on Drug Metabolism Systems—2009, Part II

    PubMed Central

    Rendic, S.; Guengerich, F.P.

    2014-01-01

    The present paper is an update of the data on the effects of diseases and environmental factors on the expression and/or activity of human cytochrome P450 (CYP) enzymes and transporters. The data are presented in tabular form (Tables 1 and 2) and are a continuation of previously published summaries on the effects of drugs and other chemicals on CYP enzymes. The collected information presented here is as stated by the cited author(s), and in cases when several references are cited the latest published information is included. Inconsistent results and conclusions obtained by different authors are highlighted, followed by discussion of the major findings. The searchable database is available as an Excel file, for information about file availability contact the corresponding author. PMID:20302566

  8. Fulminant hepatitis and fatal toxic epidermal necrolysis (Lyell disease) coincident with clarithromycin administration in an alcoholic patient receiving disulfiram therapy.

    PubMed

    Masiá, Mar; Gutiérrez, Félix; Jimeno, Araceli; Navarro, Andrés; Borrás, Joaquín; Matarredona, Jaime; Martín-Hidalgo, Alberto

    2002-02-25

    Disulfiram is widely used in the treatment of chronic alcoholism. Adverse drug reactions with fatal outcome following disulfiram therapy are infrequent, and hepatic failure accounts for most of them. Since disulfiram is a cytochrome P450 (CYP450) enzyme system inhibitor, numerous interactions with several drugs metabolized in the liver have been reported. Like disulfiram, clarithromycin inhibits a CYP450 isoenzyme, but, despite its widespread use for the treatment of respiratory tract infections, no interactions with disulfiram have been described as yet. We report a case of fatal toxic epidermal necrolysis (Lyell disease) and fulminant hepatitis shortly after starting treatment with clarithromycin in a patient who was receiving disulfiram. This is the first case of such a severe dermatosis in a patient receiving either disulfiram or clarithromycin therapy. The temporal relationship between drug administration and clinical symptoms in this case suggests a probable interaction between the 2 drugs.

  9. Effect of Aerobic and Resistance Exercise Training on Liver Enzymes and Hepatic Fat in Iranian Men With Nonalcoholic Fatty Liver Disease

    PubMed Central

    Shamsoddini, Alireza; Sobhani, Vahid; Ghamar Chehreh, Mohammad Ebrahim; Alavian, Seyed Moayed; Zaree, Ali

    2015-01-01

    Background: Nonalcoholic fatty liver disease (NAFLD) has different prevalence rates in various parts of the world and is a risk factor for diabetes and cardiovascular disease that could progress to nonalcoholic steatohepatitis, cirrhosis, and liver failure. Objectives: The current study aimed to investigate the effect of Aerobic Training (AT) and resistance training (RT) on hepatic fat content and liver enzyme levels in Iranian men. Patients and Methods: In a randomized clinical trial study, 30 men with clinically defined NAFLD were allocated into three groups (aerobic, resistance and control). An aerobic group program consisted of 45 minutes of aerobic exercise at 60% - 75% maximum heart rate intensity, a resistance group performed seven resistance exercises at intensity of 50% - 70% of 1 repetition maximum (1RM ) and the control group had no exercise training program during the study. Before and after training, anthropometry, insulin sensitivity, liver enzymes and hepatic fat were elevated. Results: After training, hepatic fat content was markedly reduced, to a similar extent, in both the aerobic and resistance exercise training groups (P ≤ 0.05). In the two exercise training groups, alanine amino transferase and aspartate amino transferase serum levels were significantly decreased compared to the control group (P = 0.002) and (P = 0.02), respectively. Moreover, body fat (%), fat mass (kg), homeostasis model assessment insulin resistance (HOMI-IR) were all improved in the AT and RT. These changes in the AT group were independent of weight loss. Conclusions: This study demonstrated that RT and AT are equally effective in reducing hepatic fat content and liver enzyme levels among patients with NAFLD. However, aerobic exercise specifically improves NAFLD independent of any change in body weight. PMID:26587039

  10. Fisetin improves glucose homeostasis through the inhibition of gluconeogenic enzymes in hepatic tissues of streptozotocin induced diabetic rats.

    PubMed

    Prasath, Gopalan Sriram; Pillai, Subramanian Iyyam; Subramanian, Sorimuthu Pillai

    2014-10-05

    Liver plays a vital role in blood glucose homeostasis. Recent studies have provided considerable evidence that hepatic glucose production (HGP) plays an important role in the development of fasting hyperglycemia in diabetes. From this perspective, diminution of HGP has certainly been considered for the treatment of diabetes. In the present study, we have analyzed the modulatory effects of fisetin, a flavonoid of strawberries, on the expression of key enzymes of carbohydrate metabolism in STZ induced experimental diabetic rats. The physiological criterions such as food and fluid intake were regularly monitored. The levels of blood glucose, plasma insulin, hemoglobin and glycosylated hemoglobin were analyzed. The mRNA and protein expression levels of gluconeogenic genes such as phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) were determined by immunoblot as well as PCR analysis. Diabetic group of rats showed significant increase in food and water intake when compared with control group of rats. Upon oral administration of fisetin as well as gliclazide to diabetic group of rats, the levels were found to be decreased. Oral administration of fisetin (10 mg/kg body weight) to diabetic rats for 30 days established a significant decline in blood glucose and glycosylated hemoglobin levels and a significant increase in plasma insulin level. The mRNA and protein expression levels of gluconeogenic genes, such as phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase), were decreased in liver tissues upon treatment with fisetin. The results of the present study suggest that fisetin improves glucose homeostasis by direct inhibition of gluconeogenesis in liver.

  11. Profiles in drug metabolism and toxicology: Richard Tecwyn Williams (1909-1979).

    PubMed

    Jones, Alan Wayne

    2015-01-01

    This article pays homage to the life and work of a veritable pioneer in toxicology and drug metabolism, namely a Welshman, Richard Tecwyn Williams, FRS. Professor Williams, or RT as he was known, made major contributions to knowledge about the metabolism and toxicology of drugs and xenobiotics during a scientific career spanning nearly 50 years. Author or coauthor of close to 400 research articles and reviews, including a classic book, entitled Detoxication Mechanisms, Williams and his research school investigated virtually all aspects of drug metabolism, especially conjugations. In particular, the concepts of phase 1 and phase II metabolic pathways were introduced by Williams; the biliary excretion of drugs was extensively studied as were species differences in drug metabolism and detoxication. Besides investigating the metabolism of many pharmaceutical drugs, such as sulfonamides and thalidomide, Williams and his group investigated the disposition and fate in the body of organic pesticides and recreational drugs of abuse, such as amphetamine, methamphetamine and lysergic acid diethylamide (LSD).

  12. Micropatterned coculture of hepatocytes on electrospun fibers as a potential in vitro model for predictive drug metabolism.

    PubMed

    Liu, Yaowen; Wei, Jiaojun; Lu, Jinfu; Lei, Dongmei; Yan, Shili; Li, Xiaohong

    2016-06-01

    The liver is the major organ of importance to determine drug dispositions in the body, thus the development of hepatocyte culture systems is of great scientific and practical interests to provide reliable and predictable models for in vitro drug screening. In the current study, to address the challenges of a rapid function loss of primary hepatocytes, the coculture of hepatocytes with fibroblasts and endothelial cells (Hep-Fib-EC) was established on micropatterned fibrous scaffolds. Liver-specific functions, such as the albumin secretion and urea synthesis, were well maintained in the coculture system, accompanied by a rapid formation of multicellular hepatocyte spheroids. The activities of phase I (CYP3A11 and CYP2C9) and phase II enzymes indicated a gradual increase for cocultured hepatocytes, and a maximum level was achieved after 5 days and maintained throughout 15 days of culture. The metabolism testing on model drugs indicated that the scaled clearance rates for hepatocytes in the Hep-Fib-EC coculture system were significantly higher than those of other culture methods, and a linear regression analysis indicated good correlations between the observed data of rats and in vitro predicted values during 15 days of culture. In addition, the enzyme activities and drug clearance rates of hepatocytes in the Hep-Fib-EC coculture model experienced sensitive responsiveness to the inducers and inhibitors of metabolizing enzymes. These results demonstrated the feasibility of micropatterned coculture of hepatocytes as a potential in vitro testing model for the prediction of in vivo drug metabolism.

  13. Adenovirus-mediated transfer of a gene encoding cholesterol 7 alpha-hydroxylase into hamsters increases hepatic enzyme activity and reduces plasma total and low density lipoprotein cholesterol.

    PubMed Central

    Spady, D K; Cuthbert, J A; Willard, M N; Meidell, R S

    1995-01-01

    Clinical interventions that accelerate conversion of cholesterol to bile acids reduce circulating low density lipoprotein (LDL) cholesterol concentrations. The initial and rate-limiting step in the bile acid biosynthetic pathway is catalyzed by hepatic cholesterol 7 alpha-hydroxylase. To examine the effects of transient primary overexpression of this enzyme on sterol metabolism and lipoprotein transport, we constructed a recombinant adenovirus in which a cDNA encoding rat 7 alpha-hydroxylase is expressed from the human cytomegalovirus immediate-early promoter (AdCMV7 alpha). Syrian hamsters administered AdCMV7 alpha intravenously accumulated transgene-specific mRNA in the liver and demonstrated a dose-dependent increase in hepatic microsomal 7 alpha-hydroxylase activity. The increased conversion of cholesterol to bile acids resulted in a compensatory increase in hepatic cholesterol synthesis. In addition, overexpression of 7 alpha-hydroxylase reduced the rate of LDL cholesterol entry into the plasma space and, in animals maintained on a Western-type diet, restored hepatic LDL receptor expression. As a consequence, plasma LDL concentrations fell by approximately 60% in animals maintained on control diet and by approximately 75% in animals consuming a Western-type diet. Plasma high density lipoprotein cholesterol levels were reduced to a lesser degree. These results demonstrate that transient upregulation of bile acid synthesis by direct transfer of a 7 alpha-hydroxylase gene favorably alters circulating lipoprotein profiles and suggest one potential molecular target for genetic strategies aimed at reducing cardiovascular risk. Images PMID:7635963

  14. Relative potency based on hepatic enzyme induction predicts immunosuppressive effects of a mixture of PCDDS/PCDFS and PCBS

    SciTech Connect

    Smialowicz, R.J.; DeVito, M.J. Williams, W.C.; Birnbaum, L.S.

    2008-03-15

    The toxic equivalency factor (TEF) approach was employed to compare immunotoxic potency of mixtures containing polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), using the antibody response to sheep erythrocytes (SRBC). Mixture-1 (MIX-1) contained TCDD, 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 1,2,3,7,8-pentachlorodibenzofuran (1-PeCDF), 2,3,4,7,8-pentachlorodibenzofuran (4-PeCDF), and 1,2,3,4,6,7,8,9-octachlorodibenzofuran (OCDF). Mixture-2 (MIX-2) contained MIX-1 and the following PCBs, 3,3',4,4'-tetrachlorobiphenyl (IUPAC No. 77), 3,3',4,4',5-pentachlorobiphenyl (126), 3,3',4,4',5,5N-hexachlorobiphenyl (169), 2,3,3',4,4'-pentachlorobiphenyl (105), 2,3',4,4',5-pentachlorobiphenyl (118), and 2,3,3',4,4',5-hexachlorobiphenyl (156). The mixture compositions were based on relative chemical concentrations in food and human tissues. TCDD equivalents (TEQ) of the mixture were estimated using relative potency factors from hepatic enzyme induction in mice [DeVito, M.J., Diliberto, J.J., Ross, D.G., Menache, M.G., Birnbaum, L.S., 1997. Dose-response relationships for polyhalogenated dioxins and dibenzofurans following subchronic treatment in mice. I .CYP1A1 and CYP1A2 enzyme activity in liver, lung and skin. Toxicol. Appl. Pharmacol. 130, 197-208; DeVito, M.J., Menache, G., Diliberto, J.J., Ross, D.G., Birnbaum L.S., 2000. Dose-response relationships for induction of CYP1A1 and CYP1A2 enzyme activity in liver, lung, and skin in female mice following subchronic exposure to polychlorinated biphenyls. Toxicol. Appl. Pharmacol. 167, 157-172] Female mice received 0, 1.5, 15, 150 or 450 ng TCDD/kg/day or approximately 0, 1.5, 15, 150 or 450 ng TEQ/kg/day of MIX-1 or MIX-2 by gavage 5 days per week for 13 weeks. Mice were immunized 3 days after the last exposure and 4 days later, body, spleen, thymus, and liver weights were measured

  15. Lack of effect of spinal anesthesia on drug metabolism

    SciTech Connect

    Whelan, E.; Wood, A.J.; Shay, S.; Wood, M. )

    1989-09-01

    The effect of spinal anesthesia on drug disposition was determined in six dogs with chronically implanted vascular catheters using propranolol as a model compound. On the first study day, 40 mg of unlabeled propranolol and 200 microCi of (3H)propranolol were injected into the portal and femoral veins respectively. Arterial blood samples were taken for 4 hr for measurement of plasma concentrations of labeled and unlabeled propranolol by high-pressure liquid chromatography (HPLC) and of (3H)propranolol by liquid scintillation counting of the HPLC eluant corresponding to each propranolol peak. Twenty-four hr later, spinal anesthesia was induced with tetracaine (mean dose 20.7 +/- 0.6 mg) with low sacral to midthoracic levels and the propranolol infusions and sampling were then repeated. Spinal anesthesia had no significant effect on either the intrinsic clearance of propranolol (2.01 +/- 0.75 L/min before and 1.9 +/- 0.7 L/min during spinal anesthesia), or on mean hepatic plasma flow (2.01 +/- 0.5 L/min before and 1.93 +/- 0.5 L/min during spinal anesthesia). The systemic clearance and elimination half-life of propranolol were also unchanged by spinal anesthesia (0.9 +/- 0.23 L/min on the first day, 0.7 +/- 0.1 L/min during spinal anesthesia; and 101 +/- 21 min on the first day, 115 +/- 16 min during spinal anesthesia, respectively). The volume of distribution (Vd) of propranolol was similarly unaffected by spinal anesthesia.

  16. Hepatic (Liver) Function Panel

    MedlinePlus

    ... related side effects. The hepatic function panel evaluates: Alanine aminotransferase (ALT). This enzyme, found in the liver, ... MORE ON THIS TOPIC Mononucleosis Hepatitis Blood Test: Alanine Aminotransferase (ALT, or SGPT) Blood Test: Aspartate Aminotransferase ( ...

  17. Suppression of Hepatic Cyp1a2 by Total Ginsenosides in Lipopolysaccharide-Treated Mice and Primary Mouse Hepatocytes.

    PubMed

    Sun, Haiyan; Yan, Yijing; Xu, Chenshu; Wan, Hongxia; Liu, Dong

    2016-03-23

    The roots of Panax ginseng (ginseng) have been extensively used in traditional Chinese medicine. However, herb-drug interactions between ginseng and other co-administered drugs are not fully understood concerning the effect of ginseng on drug metabolism and clearance. The current study aimed to elucidate the effect of total ginsenosides, a typical ginseng extract, on the regulation of Cyp1a2, a key enzyme to regulate drug metabolism under the normal and inflammatory conditions in mice. Female C57BL/6J mice treated with vehicle and lipopolysaccharide (LPS) were intragastrically administered ginseng extract for 7 days before hepatic P450 expression was analyzed. Primary mouse hepatocytes were also employed to further explore the effects of total ginsenosides on Cyp1a2 expression. The results showed that total ginsenosides in P. ginseng extract exhibited a concentration-dependent suppression on Cyp1a2 mRNA and protein level in both mice and primary mouse hepatocytes. Notably, the inhibitory effects of total ginsenosides on Cyp1a2 mRNA and protein expression were further enhanced following LPS treatment. Therefore, future research is warranted to investigate the role of ginsenosides in the regulation of hepatic CYP450s. Moreover, consumption of ginseng as food or supplement should be monitored for patients on combinational therapy, especially those with inflammatory diseases.

  18. Role of interleukin-1 in the depression of liver drug metabolism by endotoxin.

    PubMed Central

    Ghezzi, P; Saccardo, B; Villa, P; Rossi, V; Bianchi, M; Dinarello, C A

    1986-01-01

    Endotoxin-resistant C3H/HeJ mice were used to test the hypothesis that a macrophage product, possibly interleukin-1, might mediate the depression of liver cytochrome P-450-dependent drug metabolism in endotoxin-treated mice. Depression of liver drug metabolism by endotoxin was observed in normal mice (C3H/HeN) but not in C3H/HeJ mice. Serum transfer experiments demonstrated that a serum factor was responsible for the depression of liver drug metabolism. Experiments of passive transfer of peritoneal macrophages showed that this endotoxin-induced factor might be a macrophage product. In vitro experiments showed that endotoxin-stimulated monocytes produced a factor that depressed cytochrome P-450-dependent metabolism in cultured hepatocytes. Homogeneous human monocyte and recombinant interleukin-1 also depressed liver drug metabolism both in vivo and in vitro, suggesting that this macrophage product might be involved in the regulation of liver function by the immune system. PMID:3491050

  19. Modulation of CYP1A1 and CYP1A2 hepatic enzymes after oral administration of Chios mastic gum to male Wistar rats.

    PubMed

    Katsanou, Efrosini S; Kyriakopoulou, Katerina; Emmanouil, Christina; Fokialakis, Nikolas; Skaltsounis, Alexios-Leandros; Machera, Kyriaki

    2014-01-01

    Chios mastic gum (CMG), a resin derived from Pistacia lentiscus var. chia, is known since ancient times for its pharmacological activities. CYP1A1 and CYP1A2 enzymes are among the most involved in the biotransformation of chemicals and the metabolic activation of pro-carcinogens. Previous studies referring to the modulation of these enzymes by CMG have revealed findings of unclear biological and toxicological significance. For this purpose, the modulation of CYP1A1 and CYP1A2 enzymes in the liver of male Wistar rats following oral administration of CMG extract (CMGE), at the levels of mRNA and CYP1A1 enzyme activity, was compared to respective enzyme modulation following oral administration of a well-known bioactive natural product, caffeine, as control compound known to involve hepatic enzymes in its metabolism. mRNA levels of Cyp1a1 and Cyp1a2 were measured by reverse transcription real-time polymerase chain reaction and their relative quantification was calculated. CYP1A1 enzyme induction was measured through the activity of ethoxyresorufin-O-deethylase (EROD). The results indicated that administration of CMGE at the recommended pharmaceutical dose does not induce significant transcriptional modulation of Cyp1a1/2 and subsequent enzyme activity induction of CYP1A1 while effects of the same order of magnitude were observed in the same test system following the administration of caffeine at the mean daily consumed levels. The outcome of this study further confirms the lack of any toxicological or biological significance of the specific findings on liver following the administration of CMGE.

  20. 2.3.7.8-Tetrachlorodibenzo-p-Dioxin Induced Immunosuppression: Its Possible Alteration by In Vivo Administration of Specific Hepatic Enzyme Inducers.

    DTIC Science & Technology

    1987-06-27

    England .2 LIST OF ACOREVIAT:CNS AND SYMBOLS TCDD =2.3.7.8-tetrachlorodibenzo-p-dioxtn TCDF = 2.3.7 8-IOetrachlo’dibenzofuran 3MC =3-methyicholanthrene...this research program was to clarify whether drugs that in vitro inhibit TCDD binding to the hepatic cytosolic Ah "rec3ptor" such as 3MC , PNF and TCDF...these enzymes has also been performed. The study of this year has been concentrated on the effects of only two inducers, that is TCDF and 3MC , since

  1. INFLUENCE OF DIETARY SUBSTANCES ON INTESTINAL DRUG METABOLISM AND TRANSPORT

    PubMed Central

    Won, Christina S.; Oberlies, Nicholas H.; Paine, Mary F.

    2011-01-01

    Successful delivery of promising new chemical entities via the oral route is rife with challenges, some of which cannot be explained or foreseen during drug development. Further complicating an already multifaceted problem is the obvious, yet often overlooked, effect of dietary substances on drug disposition and response. Some dietary substances, particularly fruit juices, have been shown to inhibit biochemical processes in the intestine, leading to altered pharmacokinetic (PK), and potentially pharmacodynamic (PD), outcomes. Inhibition of intestinal CYP3A-mediated metabolism is the major mechanism by which fruit juices, including grapefruit juice, enhances systemic exposure to new and already marketed drugs. Inhibition of intestinal non-CYP3A enzymes and apically-located transport proteins represent recently identified mechanisms that can alter PK and PD. Several fruit juices have been shown to inhibit these processes in vitro, but some interactions have not translated to the clinic. The lack of in vitro-in vivo concordance is due largely to a lack of rigorous methods to elucidate causative ingredients prior to clinical testing. Identification of specific components and underlying mechanisms is challenging, as dietary substances frequently contain multiple, often unknown, bioactive ingredients that vary in composition and bioactivity. A translational research approach, combining expertise from clinical pharmacologists and natural products chemists, is needed to develop robust models describing PK/PD relationships between a given dietary substance and drug of interest. Validation of these models through well-designed clinical trials would facilitate development of common practice guidelines for managing drug-dietary substance interactions appropriately. PMID:21189136

  2. Effects of alcohol on human carboxylesterase drug metabolism

    PubMed Central

    Parker, Robert B.; Hu, Zhe-Yi; Meibohm, Bernd; Laizure, S. Casey

    2015-01-01

    Background and Objective Human carboxylesterase-1 (CES1) and human carboxylesterase-2 (CES2) play an important role in metabolizing many medications. Alcohol is a known inhibitor of these enzymes but the relative effect on CES1 and CES2 is unknown. The aim of this study is to determine the impact of alcohol on the metabolism of specific probes for CES1 (oseltamivir) and CES2 (aspirin). Methods The effect of alcohol on CES1- and CES2-mediated probe drug hydrolysis was determined in vitro using recombinant human carboxylesterase. To characterize the in vivo effects of alcohol, healthy volunteers received each probe drug alone and in combination with alcohol followed by blood sample collection and determination of oseltamivir, aspirin, and respective metabolite pharmacokinetics. Results Alcohol significantly inhibited oseltamivir hydrolysis by CES1 in vitro but did not affect aspirin metabolism by CES2. Alcohol increased the oseltamivir area under the plasma concentration-time curve (AUC) from 0-6 h by 27% (range 11-46%, p=0.011) and decreased the metabolite/oseltamivir AUC 0-6 h ratio by 34% (range 25-41%, p<0.001). Aspirin pharmacokinetics were not affected by alcohol. Conclusions Alcohol significantly inhibited the hydrolysis of oseltamivir by CES1 both in vitro and in humans, but did not affect the hydrolysis of aspirin to salicylic acid by CES2. These results suggest that alcohol's inhibition of CES1 could potentially result in clinically significant drug interactions with other CES1-substrate drugs, but it is unlikely to significantly affect CES2-substrate drug hydrolysis. PMID:25511794

  3. [Activity of the marker liver enzymes under the conditions of toxic hepatitis and alimentary deprivation of protein].

    PubMed

    Voloshchuk, O N; Kopyl'chuk, G P; Buchkovskaia, I M

    2014-01-01

    The activity of the sorbitoldehydrogenase (SDH), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) in the blood serum of rats with acetaminophen-induced hepatitis under the conditions of alimentary deprivation of protein was studied. The animals were divided into 3 groups: 1--rats with acute acetaminophen-induced hepatitis, maintained on the full ration; 2--rats with acute acetaminophen-induced hepatitis, maintained under the conditions of alimentary deprivation of protein; 3--control. The activity of the sorbitol dehydrogenase in blood serum was determined by the kinetic method, activity of the alanine aminotransferase and alkaline phosphatase - photometrically. It is shown, that in animals with the model hepatitis the activity of sorbitol dehydrogenase in blood serum increases 20-fold, wherein statistical significance between animals with hepatitis maintained under the conditions of full ration and those of low-protein diet is not established. In the group of animals with acetaminophen-induced hepatitis the preservation on the control level of the alkaline phosphatase activity on the base of the increase of alanine aminotransferase by 2.2 times and ratio ALT/ALP>5 testifies about hepatocellular liver injury. In the group of animals with drug-induced hepatitis and alimentary deprivation of protein, the increase of the alkaline phosphatase and alanine aminotransferase activity is observed, herewith the ratio ALT/ALP ranges from 2 to 5 and testifies about mixed liver injury. The conclusion was made, that alimentary deprivation of protein is the critical factor for the development of the disturbances of functional and structural liver integrity, and the therapeutic approaches to the correction of the drug-induced liver injury should be different depending on the value of protein ration in the anamnesis, taking into account the different types of liver injury.

  4. The effect of insulin on plasma glucose concentrations, expression of hepatic glucose transporters and key gluconeogenic enzymes during the perinatal period in broiler chickens.

    PubMed

    Franssens, Lies; Lesuisse, Jens; Wang, Yufeng; Willems, Els; Willemsen, Hilke; Koppenol, Astrid; Guo, Xiaoquan; Buyse, Johan; Decuypere, Eddy; Everaert, Nadia

    2016-06-01

    Chickens have blood glucose concentrations that are twofold higher than those observed in mammals. Moreover, the insulin sensitivity seems to decrease with postnatal age in both broiler and layer chickens. However, little is known about the response of insulin on plasma glucose concentrations and mRNA abundance of hepatic glucose transporters 1, 2, 3, 8, 9 and 12 (GLUT1, 2, 3, 8, 9 and 12) and three regulatory enzymes of the gluconeogenesis, phosphoenolpyruvate carboxykinase 1 and 2 (PCK1 and 2) or fructose-1,6-biphosphatase 1 (FBP1) in chicks during the perinatal period. In the present study, broiler embryos on embryonic day (ED)16, ED18 or newly-hatched broiler chicks were injected intravenously with bovine insulin (1μg/g body weight (BW)) to examine plasma glucose response and changes in hepatic mRNA abundance of the GLUTs, PCK1 and 2 and FBP1. Results were compared with a non-treated control group and a saline-injected sham group. Plasma glucose levels of insulin-treated ED18 embryos recovered faster from their minimum level than those of insulin-treated ED16 embryos or newly-hatched chicks. In addition, at the minimum plasma glucose level seven hours post-injection (PI), hepatic GLUT2, FBP1 and PCK2 mRNA abundance was decreased in insulin-injected embryos, compared to sham and control groups, being most pronounced when insulin injection occurred on ED16.

  5. Effects of Fresh Yellow Onion Consumption on CEA, CA125 and Hepatic Enzymes in Breast Cancer Patients: A Double- Blind Randomized Controlled Clinical Trial.

    PubMed

    Jafarpour-Sadegh, Farnaz; Montazeri, Vahid; Adili, Ali; Esfehani, Ali; Rashidi, Mohammad-Reza; Mesgari, Mehran; Pirouzpanah, Saeed

    2015-01-01

    Onion (Allium cepa) consumption has been remarked in folk medicine which has not been noted to be administered so far as an adjunct to conventional doxorubicin-based chemotherapy in breast cancer patients. To our knowledge, this is the first study aimed to investigate the effects of consuming fresh yellow onions on hepatic enzymes and cancer specific antigens compared with a low-onion containing diet among breast cancer (BC) participants treated with doxorubicin. This parallel design randomized controlled clinical trial was conducted on 56 BC patients whose malignancy was confirmed with histopathological examination. Subjects were assigned in a stratified-random allocation into either group received body mass index dependent 100-160 g/d of onion as high onion group (HO; n=28) or 30-40 g/d small onion in low onion group (LO; n=28) for eight weeks intervention. Participants, care givers and laboratory assessor were blinded to the assignments (IRCT registry no: IRCT2012103111335N1). The compliance of participants in the analysis was appropriate (87.9%). Comparing changes throughout pre- and post-dose treatments indicated significant controls on carcinoembryonic antigen, cancer antigen-125 and alkaline phosphatase levels in the HO group (P<0.05). Our findings for the first time showed that regular onion administration could be effective for hepatic enzyme conveying adjuvant chemotherapy relevant toxicity and reducing the tumor markers in BC during doxorubicin-based chemotherapy.

  6. Experiment K304: Studies of specific hepatic enzymes and liver constituents involved in the conversion of carbohydrates to lipids in rats exposed to prolonged space flight

    NASA Technical Reports Server (NTRS)

    Abraham, S.; Klein, H. P.; Lin, C. Y.; Volkmann, C.; Tigranyan, R. A.; Vetrova, E. G.

    1981-01-01

    The effects of space flight on the activities of 26 enzymes concerned with carbohydrate and lipid metabolism in hepatic tissue taken from male Wistar rats are investigated. These activities were measured in the various hepatic cell compartments, i.e., cytosol, mitochondria and microsomes. In addition, the levels of glycogen, total lipids, phospholipids, triglycerides, cholesterol, cholesterol esters, and the fatty acid composition of the rat livers were also examined and quantified. A similar group of ground-based rats treated in an identical manner served as controls. Both flight and synchronous control rats were sacrificed at three time intervals: R+0, 7-11 hours after recovery; R+6, after 6 days; R+6(S), after 6 days (having undergone 2-5 hour periods of fixed stress in a "backupward" position on days 0, 3, 4, 5 and 6) and R+29, after 29 days post-flight. Although most of the enzyme activities and the amounts of liver constituents studied were unaffected by the period of weightlessness, some significant differences were observed.

  7. Reversal of arsenic-induced hepatic apoptosis with combined administration of DMSA and its analogues in guinea pigs: role of glutathione and linked enzymes.

    PubMed

    Mishra, Deepshikha; Mehta, Ashish; Flora, Swaran J S

    2008-02-01

    Arsenicosis, due to contaminated drinking water in the Indo-Bangladesh region, is a serious health hazard in terms of morbidity and mortality. Reactive oxygen species (ROS) generated due to arsenic toxicity have been attributed as one of the initial signals that impart cellular toxicity, which is controlled by the internal antioxidant glutathione (GSH). In the present study, we investigated (i) the role of GSH and its linked enzymes, glutathione peroxidase and glutathione reductase, in reversing chronic arsenic toxicity using a thiol chelating agent, meso-2,3-dimercaptosuccinic acid (DMSA), or one of its analogues individually or in combination; (ii) if alterations in the carbon side chain of DMSA increased efficacy; and (iii) whether the combination therapy enhance arsenic removal from hepatic tissue and prevent hepatic apoptosis. Results indicated that chronic arsenic exposure led to a ROS-mediated, mitochondrial-driven, caspase-dependent apoptosis in hepatic cells with a significant increase in glutathione disulfide (GSSG) levels and decreased glutathione reductase levels. Monotherapy with DMSA and its analogues did show minimal recovery postchelation. However, the combination of DMSA with long carbon chain analogues like monoisoamyl DMSA (MiADMSA) or monocyclohexyl DMSA (MchDMSA) showed a better efficacy in terms of reducing the arsenic burden as well as reversing altered biochemical variables indicative of oxidative stress and apoptosis. We also observed that GSH and its linked enzymes, especially glutathione reductase, play a vital role in scavenging ROS, maintaining GSH pools, and providing clinical recoveries. On the basis of the above observations, we recommend that combinational therapy of DMSA and its long carbon chain analogues MiADMSA or MchDMSA would be more effective in arsenic toxicity.

  8. Expression and Regulation of Drug Transporters and Metabolizing Enzymes in the Human Gastrointestinal Tract.

    PubMed

    Drozdzik, M; Oswald, S

    2016-01-01

    Orally administered drugs must pass through the intestinal wall and then through the liver before reaching systemic circulation. During this process drugs are subjected to different processes that may determine the therapeutic value. The intestinal barrier with active drug metabolizing enzymes and drug transporters in enterocytes plays an important role in the determination of drug bioavailability. Accumulating information demonstrates variable distribution of drug metabolizing enzymes and transporters along the human gastrointestinal tract (GI), that creates specific barrier characteristics in different segments of the GI. In this review, expression of drug metabolizing enzymes and transporters in the healthy and diseased human GI as well as their regulatory aspects: genetic, miRNA, DNA methylation are outlined. The knowledge of unique interplay between drug metabolizing enzymes and transporters in specific segments of the GI tract allows more precise definition of drug release sites within the GI in order to assure more complete bioavailability and prediction of drug interactions.

  9. Review of current chemoinformatic tools for modeling important aspects of CYPs-mediated drug metabolism. Integrating metabolism data with other biological profiles to enhance drug discovery.

    PubMed

    Speck-Planche, Alejandro; Cordeiro, Maria Natalia Dias Soeiro

    2014-01-01

    The study of the metabolism of xenobiotics by the human body is an essential stage in the complex and expensive process of drug discovery, being one of the main causes of disapproval and/or withdrawal of drugs. Regarding this, enzymes known as cytochromes P450 (CYPs) play a very decisive role in the biotransformation of many chemicals. For this reason, the use of chemoinformatics to predict and /or analyze from different points of view CYPs-mediated drug metabolism, can help to reduce time and financial resources. This work is focused on the most remarkable advances in the last 5 years of the chemoinformatics tools towards the virtual analysis of CYPsmediated drug metabolism. First, a brief section is dedicated to the applicability of chemoinformatics in different areas associated with drug metabolism. Then, both the models for prediction of CYPs substrates and those allowing the assessment of sites of metabolism (SOM) are discussed. At the same time, the principal limitations of the current chemoinformatic tools are pointed out. Finally, and taking into account that metabolism is an essential step in the whole process of designing any drug, we introduce here as a case of study, the first multitasking model for quantitative-structure biological effect relationships (mtk-QSBER). The purpose of this model is to integrate different types of biological profiles such as ADMET (absorption, distribution, metabolism, excretion, toxicity) profiles and antistaphylococci activities. The mtk-QSBER model was created by employing a heterogeneous dataset of more than 66000 cases tested in 6510 different experimental conditions. The model displayed a total accuracy higher than 94%. To the best of our knowledge, this is the first attempt to complement metabolism assays with other relevant biological data in order to speed up the discovery of efficacious antistaphylococci agents.

  10. Chronic alcohol intake up-regulates hepatic expressions of carotenoid cleavage enzymes and peroxisomal proliferator-activated receptors in rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Excessive and chronic alcohol intake leads to a lower hepatic vitamin A status by interfering with vitamin A metabolism.Dietary provitamin A carotenoids can be converted into vitamin A mainly by carotenoid 15,15’-monooxygenase 1 (CMO1) and, to a lesser degree, carotenoid 9910’-monooxygenase 2 (CMO2)...

  11. Feeding glycerol-enriched yeast culture improves lactation performance, energy status, and hepatic gluconeogenic enzyme expression of dairy cows during the transition period.

    PubMed

    Ye, G; Liu, J; Liu, Y; Chen, X; Liao, S F; Huang, D; Huang, K

    2016-06-01

    This study aimed to evaluate the effects of feeding glycerol-enriched yeast culture (GY) on feed intake, lactation performance, blood metabolites, and expression of some key hepatic gluconeogenic enzymes in dairy cows during the transition period. Forty-four multiparous transition Holstein cows were blocked by parity, previous 305-d mature equivalent milk yield, and expected calving date and randomly allocated to 4 dietary treatments: Control (no additive), 2 L/d of GY (75.8 g/L glycerol and 15.3 g/L yeast), 150 g/d of glycerol (G; 0.998 g/g glycerol), and 1 L/d of yeast culture (Y; 31.1 g/L yeast). All additives were top-dressed and hand mixed into the upper one-third of the total mixed ration in the morning from -14 to +28 d relative to calving. Results indicated that the DMI, NE intake, change of BCS, and milk yields were not affected by the treatments ( > 0.05). Supplementation of GY or Y increased milk fat percentages, milk protein percentages, and milk protein yields relative to the Control or G group ( < 0.05). Cows fed GY or G had higher glucose levels and lower β-hydroxybutyric acid (BHBA) and NEFA levels in plasma than cows fed the Control ( < 0.05) and had lower NEFA levels than cows fed Y ( < 0.05). On 14 d postpartum, cows fed GY or G had higher enzyme activities, mRNA, and protein expression of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C; < 0.05); higher enzyme activities ( < 0.05) and a tendency toward higher mRNA expression ( < 0.10) of glycerol kinase (GK); and a tendency toward higher enzyme activities of pyruvate carboxylase (PC) in the liver ( < 0.10) when compared with cows fed Control or Y. The enzyme activities, mRNA, and protein expression of PEPCK-C, PC, and GK did not differ between cows fed GY and G ( > 0.10). In conclusion, dietary GY or Y supplementation increased the milk fat and protein content of the cows in early lactation and GY or G supplementation improved the energy status as indicated by greater plasma glucose and

  12. High-throughput screening in drug metabolism and pharmacokinetic support of drug discovery.

    PubMed

    White, R E

    2000-01-01

    The application of rapid methods currently used for screening discovery drug candidates for metabolism and pharmacokinetic characteristics is discussed. General considerations are given for screening in this context, including the criteria for good screens, the use of counterscreens, the proper sequencing of screens, ambiguity in the interpretation of results, strategies for false positives and negatives, and the special difficulties encountered in drug metabolism and pharmacokinetic screening. Detailed descriptions of the present status of screening are provided for absorption potential, blood-brain barrier penetration, inhibition and induction of cytochrome P450, pharmacokinetics, biotransformation, and computer modeling. Although none of the systems currently employed for drug metabolism and pharmacokinetic screening can be considered truly high-throughput, several of them are rapid enough to be a practical part of the screening paradigm for modern, fast-moving discovery programs.

  13. Predicting drug metabolism--an evaluation of the expert system METEOR.

    PubMed

    Testa, Bernard; Balmat, Anne-Loyse; Long, Anthony; Judson, Philip

    2005-07-01

    The paper begins with a discussion of the goals of metabolic predictions in early drug research, and some difficulties toward this objective, mainly the various substrate and product selectivities characteristic of drug metabolism. The major in silico approaches to predict drug metabolism are then classified and summarized. A discrimination is, thus, made between 'local' and 'global' systems. In its second part, an evaluation of METEOR, a rule-based expert system used to predict the metabolism of drugs and other xenobiotics, is reported. The published metabolic data of ten substrates were used in this evaluation, the overall results being discussed in terms of correct vs. disputable (i.e., false-positive and false-negative) predictions. The predictions for four representative substrates are presented in detail (Figs. 1-4), illustrating the interest of such an evaluation in identifying where and how predictive rules can be improved.

  14. Growing steers grazing high versus low endophyte (Neotyphodium coenophialum)-infected tall fescue have reduced serum enzymes, increased hepatic glucogenic enzymes, and reduced liver and carcass mass.

    PubMed

    Brown, K R; Anderson, G A; Son, K; Rentfrow, G; Bush, L P; Klotz, J L; Strickland, J R; Boling, J A; Matthews, J C

    2009-02-01

    It is well established that grazing Neotyphodium coenophialum-infected forages results in reduced BW gain and serum prolactin concentrations of cattle. The objective of this study was to determine the potential effects of toxic endophyte-infected tall fescue consumption on blood metabolites, carcass characteristics, and content of proteins critical for AA metabolism in the liver, kidney, and LM tissue of growing steers. Steers grazed a low toxic endophyte (LE; 0.023 microg/g ergot alkaloids) tall fescue-mixed grass pasture (n = 9; BW = 266 +/- 10.9 kg; 5.7 ha) or a high toxic endophyte (HE; 0.746 microg/g of ergot alkaloids) tall fescue pasture (n = 10; BW = 267 +/- 14.5 kg; 5.7 ha) from June 14 through at least September 11 (> or =89 d). No difference was observed for BW (P < 0.10) for the overall 85-d growth period. Also, no differences were observed for ribeye area/100 kg of HCW (P > 0.91), backfat (P > 0.95), or backfat/100 kg of HCW (P > 0.67). However, ADG (P < 0.01), final BW (P < 0.05), HCW (P < 0.01), dressing percentage (P < 0.01), ribeye area (P < 0.01), whole liver wet weight (P < 0.01), and whole liver wet weight/100 kg of end BW (P < 0.01) were greater for LE steers than HE steers. After 85 d of grazing, serum concentrations of alkaline phosphatase (P < 0.05), alanine aminotransferase (P < 0.01), aspartate aminotransferase (P < 0.03), cholesterol (P < 0.01), lactate dehydrogenase (P < 0.01), and prolactin (P < 0.01) were less for HE than LE steers. At slaughter, hepatic content of cytosolic phosphoenolpyruvate carboxykinase (P < 0.01) was greater in HE steers than LE steers. Hepatic content of aspartate aminotransferase (P < 0.01) also was greater, whereas renal and LM content were not (P > or = 0.42). No differences (P > or = 0.15) were observed for hepatic, renal, and LM content of alanine aminotransferase, glutamate dehydrogenase, glutamine synthetase, and 3 glutamate transport proteins. These data indicate that the HE steers displayed classic

  15. In vitro and in vivo effects of promethazine (Phenergan) on drug metabolism.

    PubMed

    Fernandez, G; Castro, J A

    1978-02-01

    Prolongation effects of promethazine on the pentobarbital sleeping time are not due to interactions of this drug with cytochrome P-450 or cytochrome c reductase or inhibition of drug metabolism because pentobarbital plasma levels in promethazine treated animals before awakening are not different than in controls. Results suggest additive effects of both drugs on the central nervous system. Those interactions do however play a role during in vitro studies.

  16. Bioprinting of Micro-Organ Tissue Analog for Drug Metabolism Study

    NASA Astrophysics Data System (ADS)

    Sun, Wei

    An evolving application of tissue engineering is to develop in vitro 3D cell/tissue models for drug screening and pharmacological study. In order to test in space, these in vitro models are mostly manufactured through micro-fabrication techniques and incorporate living cells with MEMS or microfluidic devices. These cell-integrated microfluidic devices, or referred as microorgans, are effective in furnishing reliable and inexpensive drug metabolism and toxicity studies [1-3]. This paper will present an on-going research collaborated between Drexel University and NASA JSC Radiation Physics Laboratory for applying a direct cell printing technique to freeform fabrication of 3D liver tissue analog in drug metabolism study. The paper will discuss modeling, design, and solid freeform fabrication of micro-fluidic flow patterns and bioprinting of 3D micro-liver chamber that biomimics liver physiological microenvironment for enhanced drug metabolization. Technical details to address bioprinting of 3D liver tissue analog, integration with a microfluidic device, and basic drug metabolism study for NASA's interests will presented. 1. Holtorf H. Leslie J. Chang R, Nam J, Culbertson C, Sun W, Gonda S, "Development of a Three-Dimensional Tissue-on-a-Chip Micro-Organ Device for Pharmacokinetic Analysis", the 47th Annual Meeting of the American Society for Cell Biology, Washington, DC, December 1-5, 2007. 2. Chang, R., Nam, J., Culbertson C., Holtorf, H., Jeevarajan, A., Gonda, S. and Sun, W., "Bio-printing and Modeling of Flow Patterns for Cell Encapsulated 3D Liver Chambers For Pharmacokinetic Study", TERMIS North America 2007 Conference and Exposition, Westin Harbour Castle, Toronto, Canada, June 13-16, 2007. 3.Starly, B., Chang, R., Sun, W., Culbertson, C., Holtorf, H. and Gonda, S., "Bioprinted Tissue-on-chip Application for Pharmacokinetic Studies", Proceedings of World Congress on Tissue Engineering and Regenerative Medicine, Pittsburgh, PA, USA, April 24-27, 2006.

  17. Epigenetic regulation of ADME-related genes: focus on drug metabolism and transport.

    PubMed

    Zhong, Xiao-bo; Leeder, J Steven

    2013-10-01

    Epigenetic regulation of gene expression refers to heritable factors that are functionally relevant genomic modifications but that do not involve changes in DNA sequence. Examples of such modifications include DNA methylation, histone modifications, noncoding RNAs, and chromatin architecture. Epigenetic modifications are crucial for packaging and interpreting the genome, and they have fundamental functions in regulating gene expression and activity under the influence of physiologic and environmental factors. Recently, epigenetics has become one of the fastest-growing areas of science and has now become a central issue in biologic studies of development and disease pathogenesis. The interest in epigenetics is also true for studies of drug metabolism and transport. In this issue of Drug Metabolism and Disposition, a series of articles is presented to demonstrate the role of epigenetic factors in regulating the expression of genes involved in drug absorption, distribution, metabolism, and excretion in organ development, tissue-specific gene expression, sexual dimorphism, and in the adaptive response to xenobiotic exposure, both therapeutic and toxic. The articles also demonstrate that, in addition to genetic polymorphisms, epigenetics may also contribute to wide interindividual variations in drug metabolism and transport. Identification of functionally relevant epigenetic biomarkers in human specimens has the potential to improve prediction of drug responses based on patient's epigenetic profiles.

  18. Unequal prognostic potentials of p53 gain-of-function mutations in human cancers associate with drug-metabolizing activity.

    PubMed

    Xu, J; Wang, J; Hu, Y; Qian, J; Xu, B; Chen, H; Zou, W; Fang, J-Y

    2014-03-06

    Mutation of p53 is the most common genetic change in human cancer, causing complex effects including not only loss of wild-type function but also gain of novel oncogenic functions (GOF). It is increasingly likely that p53-hotspot mutations may confer different types and magnitudes of GOF, but the evidences are mainly supported by cellular and transgenic animal models. Here we combine large-scale cancer genomic data to characterize the prognostic significance of different p53 mutations in human cancers. Unexpectedly, only mutations on the Arg248 and Arg282 positions displayed significant association with shorter patient survival, but such association was not evident for other hotspot GOF mutations. Gene set enrichment analysis on these mutations revealed higher activity of drug-metabolizing enzymes, including the CYP3A4 cytochrome P450. Ectopic expression of p53 mutant R282W in H1299 and SaOS2 cells significantly upregulated CYP3A4 mRNA and protein levels, and cancer cell lines bearing mortality-associated p53 mutations display higher CYP3A4 expression and resistance to several CYP3A4-metabolized chemotherapeutic drugs. Our results suggest that p53 mutations have unequal GOF activities in human cancers, and future evaluation of p53 as a cancer biomarker should consider which mutation is present in the tumor, rather than having comparison between wild-type and mutant genotypes.

  19. CRISPR knockout rat cytochrome P450 3A1/2 model for advancing drug metabolism and pharmacokinetics research.

    PubMed

    Lu, Jian; Shao, Yanjiao; Qin, Xuan; Liu, Daozhi; Chen, Ang; Li, Dali; Liu, Mingyao; Wang, Xin

    2017-02-20

    Cytochrome P450 (CYP) 3A accounts for nearly 30% of the total CYP enzymes in the human liver and participates in the metabolism of over 50% of clinical drugs. Moreover, CYP3A plays an important role in chemical metabolism, toxicity, and carcinogenicity. New animal models are needed to investigate CYP3A functions, especially for drug metabolism. In this report, Cyp3a1/2 double knockout (KO) rats were generated by CRISPR-Cas9 technology, and then were characterized for viability and physiological status. The Cyp3a1/2 double KO rats were viable and fertile, and had no obvious physiological abnormities. Compared with the wild-type (WT) rat, Cyp3a1/2 expression was completely absent in the liver of the KO rat. In vitro and in vivo metabolic studies of the CYP3A1/2 substrates indicated that CYP3A1/2 was functionally inactive in double KO rats. The Cyp3a1/2 double KO rat model was successfully generated and characterized. The Cyp3a1/2 KO rats are a novel rodent animal model that will be a powerful tool for the study of the physiological and pharmacological roles of CYP3A, especially in drug and chemical metabolism in vivo.

  20. The 2014 Bernard B. Brodie Award Lecture—Epoxide Hydrolases: Drug Metabolism to Therapeutics for Chronic Pain

    PubMed Central

    Kodani, Sean D.

    2015-01-01

    Dr. Bernard Brodie’s legacy is built on fundamental discoveries in pharmacology and drug metabolism that were then translated to the clinic to improve patient care. Similarly, the development of a novel class of therapeutics termed the soluble epoxide hydrolase (sEH) inhibitors was originally spurred by fundamental research exploring the biochemistry and physiology of the sEH. Here, we present an overview of the history and current state of research on epoxide hydrolases, specifically focusing on sEHs. In doing so, we start with the translational project studying the metabolism of the insect juvenile hormone mimic R-20458 [(E)-6,7-epoxy-1-(4-ethylphenoxy)-3,7-dimethyl-2-octene], which led to the identification of the mammalian sEH. Further investigation of this enzyme and its substrates, including the epoxyeicosatrienoic acids, led to insight into mechanisms of inflammation, chronic and neuropathic pain, angiogenesis, and other physiologic processes. This basic knowledge in turn led to the development of potent inhibitors of the sEH that are promising therapeutics for pain, hypertension, chronic obstructive pulmonary disorder, arthritis, and other disorders. PMID:25762541

  1. Fast evaluation of enantioselective drug metabolism by electrophoretically mediated microanalysis: application to fluoxetine metabolism by CYP2D6.

    PubMed

    Asensi-Bernardi, Lucía; Martín-Biosca, Yolanda; Escuder-Gilabert, Laura; Sagrado, Salvador; Medina-Hernández, María José

    2013-12-01

    In this work, a capillary electrophoretic methodology for the enantioselective in vitro evaluation of drugs metabolism is applied to the evaluation of fluoxetine (FLX) metabolism by cytochrome 2D6 (CYP2D6). This methodology comprises the in-capillary enzymatic reaction and the chiral separation of FLX and its major metabolite, norfluoxetine enantiomers employing highly sulfated β-CD and the partial filling technique. The methodology employed in this work is a fast way to obtain a first approach of the enantioselective in vitro metabolism of racemic drugs, with the additional advantage of an extremely low consumption of enzymes, CDs and all the reagents involved in the process. Michaelis-Menten kinetic parameters (Km and Vmax ) for the metabolism of FLX enantiomers by CYP2D6 have been estimated by nonlinear fitting of experimental data to the Michaelis-Menten equation. Km values have been found to be 30 ± 3 μM for S-FLX and 39 ± 5 μM for R-FLX. Vmax estimations were 28.6 ± 1.2 and 34 ± 2 pmol·min(-1) ·(pmol CYP)(-1) for S- and R-FLX, respectively. Similar results were obtained using a single enantiomer (R-FLX), indicating that the use of the racemate is a good option for obtaining enantioselective estimations. The results obtained show a slight enantioselectivity in favor of R-FLX.

  2. CRISPR knockout rat cytochrome P450 3A1/2 model for advancing drug metabolism and pharmacokinetics research

    PubMed Central

    Lu, Jian; Shao, Yanjiao; Qin, Xuan; Liu, Daozhi; Chen, Ang; Li, Dali; Liu, Mingyao; Wang, Xin

    2017-01-01

    Cytochrome P450 (CYP) 3A accounts for nearly 30% of the total CYP enzymes in the human liver and participates in the metabolism of over 50% of clinical drugs. Moreover, CYP3A plays an important role in chemical metabolism, toxicity, and carcinogenicity. New animal models are needed to investigate CYP3A functions, especially for drug metabolism. In this report, Cyp3a1/2 double knockout (KO) rats were generated by CRISPR-Cas9 technology, and then were characterized for viability and physiological status. The Cyp3a1/2 double KO rats were viable and fertile, and had no obvious physiological abnormities. Compared with the wild-type (WT) rat, Cyp3a1/2 expression was completely absent in the liver of the KO rat. In vitro and in vivo metabolic studies of the CYP3A1/2 substrates indicated that CYP3A1/2 was functionally inactive in double KO rats. The Cyp3a1/2 double KO rat model was successfully generated and characterized. The Cyp3a1/2 KO rats are a novel rodent animal model that will be a powerful tool for the study of the physiological and pharmacological roles of CYP3A, especially in drug and chemical metabolism in vivo. PMID:28218310

  3. Angiotensin-converting enzyme inhibitors improve hepatic steatosis by modulating expression of tumour necrosis factor-alpha, interleukin-6 and adiponectin receptor-2 in rats with type 2 diabetes.

    PubMed

    Zhang, Xia; Li, Zhong-Zhuan; Liu, Dong-Fang; Xu, Xin; Mei, Zhe-Chuan; Shen, Wei

    2009-07-01

    1. Angiotensin-converting enzyme inhibitors (ACEI) are hypotensive drugs that have been shown to prevent Type 2 diabetes mellitus (T2DM) in high-risk individuals. However, in T2DM, the effects of ACEI on hepatic steatosis are not known. The aim of the present study was to examine the effects of ACEI on changes in liver histology and hepatic mRNA expression of adipokines in rats with T2DM. 2. Thirty-six rats were divided into a normal control group, a T2DM group and a fosinopril-treated group. After six weeks of treatment with 5 mg/kg per day fosinopril, an ACEI, changes in liver histology, serum fasting glucose (FG), insulin, triglyceride (TG), total cholesterol (TC), alanine aminotransferase (ALT), aspartate aminotransferase (AST), tumour necrosis factor (TNF)-alpha, interleukin (IL)-6, adiponectin were evaluated, as was hepatic TNF-alpha, IL-6 and adiponectin receptor-2 (adipoR2) mRNA expression. 3. The degree of hepatic steatosis and inflammation, serum FG, insulin, TG, TC, ALT, TNF-alpha and IL-6 concentrations and hepatic TNF-alpha and IL-6 mRNA expression were significantly higher in rats with T2DM than in normal controls. Serum adiponectin concentrations and hepatic adipoR2 mRNA expression in rats with T2DM were significantly lower than in normal controls. Fosinopril significantly reduced the degree of hepatic steatosis, serum FG, insulin, ALT, TNF-alpha and IL-6 concentrations and hepatic TNF-alpha and IL-6 mRNA expression. Fosinopril significantly increased serum adiponectin concentrations and hepatic adipoR2 mRNA expression. 4. In conclusion, the ACEI improved insulin sensitivity and hepatic steatosis in rats with T2DM by increasing circulating adiponectin and hepatic adipoR2 levels, in addition to reducing pro-inflammatory cytokine levels in the circulation and liver.

  4. Lupinus albus Conglutin Gamma Modifies the Gene Expressions of Enzymes Involved in Glucose Hepatic Production In Vivo.

    PubMed

    González-Santiago, Ana E; Vargas-Guerrero, Belinda; García-López, Pedro M; Martínez-Ayala, Alma L; Domínguez-Rosales, José A; Gurrola-Díaz, Carmen M

    2017-01-18

    Lupinus albus seeds contain conglutin gamma (Cγ) protein, which exerts a hypoglycemic effect and positively modifies proteins involved in glucose homeostasis. Cγ could potentially be used to manage patients with impaired glucose metabolism, but there remains a need to evaluate its effects on hepatic glucose production. The present study aimed to analyze G6pc, Fbp1, and Pck1 gene expressions in two experimental animal models of impaired glucose metabolism. We also evaluated hepatic and renal tissue integrity following Cγ treatment. To generate an insulin resistance model, male Wistar rats were provided 30% sucrose solution ad libitum for 20 weeks. To generate a type 2 diabetes model (STZ), five-day-old rats were intraperitoneally injected with streptozotocin (150 mg/kg). Each animal model was randomized into three subgroups that received the following oral treatments daily for one week: 0.9% w/v NaCl (vehicle; IR-Ctrl and STZ-Ctrl); metformin 300 mg/kg (IR-Met and STZ-Met); and Cγ 150 mg/kg (IR-Cγ and STZ-Cγ). Biochemical parameters were assessed pre- and post-treatment using colorimetric or enzymatic methods. We also performed histological analysis of hepatic and renal tissue. G6pc, Fbp1, and Pck1 gene expressions were quantified using real-time PCR. No histological changes were observed in any group. Post-treatment G6pc gene expression was decreased in the IR-Cγ and STZ-Cγ groups. Post-treatment Fbp1 and Pck1 gene expressions were reduced in the IR-Cγ group but increased in STZ-Cγ animals. Overall, these findings suggest that Cγ is involved in reducing hepatic glucose production, mainly through G6pc inhibition in impaired glucose metabolism disorders.

  5. Effects of dietary tannic acid on the growth, hepatic gene expression, and antioxidant enzyme activity in Brandt's voles (Microtus brandti).

    PubMed

    Ye, Man-Hong; Nan, Yan-Lei; Ding, Meng-Meng; Hu, Jun-Bang; Liu, Qian; Wei, Wan-Hong; Yang, Sheng-Mei

    2016-01-01

    This study was designed to investigate the physiological and biochemical responses of Brandt's voles to the persistent presence of dietary tannic acid. The diet for animals in the experimental group was supplemented with 3% dietary tannic acid for 5weeks. The control group received a commercial lab chow. No significant differences were detected in body weight, organ (heart, kidney, and liver) weights, and organ parameters between animals from two groups. However, voles in the experimental group had significantly higher daily food intake, increased contents of proline and histidine in saliva and feces after protein hydrolysis, and elevated hepatic expression of transferrin than the control. Our results suggested the existence of adaptive strategies developed in Brandt's voles to overcome the adverse effects of dietary tannic acid. (1) Food consumption was increased to satisfy their nutritional demands. (2) The secretion of tannic-acid-binding salivary proteins was promoted. (3) The absorption of iron was enhanced. These alterations contributed to neutralize the negative effects of tannic acid and maintain body mass in animals supplemented with tannic acid. As the result of the consumption of tannic acid, hepatic expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase was significantly decreased, while the overall potential of the antioxidant system, characterized by increased hepatic enzymatic activities of catalase and glutathione peroxidase, was enhanced. Our results also implied the involvement of tannic acid in the regulation of lipid metabolism and oxidative stress in voles.

  6. Effect of Commiphora mukul gum resin on hepatic marker enzymes, lipid peroxidation and antioxidants status in pancreas and heart of streptozotocin induced diabetic rats

    PubMed Central

    Ramesh, B; Karuna, R; Sreenivasa, Reddy S; Haritha, K; Sai, Mangala D; Sasi, Bhusana Rao B; Saralakumari, D

    2012-01-01

    Objective To study the antioxidant efficacy of Commiphora mukul (C. mukul) gum resin ethanolic extract in streptozotocin (STZ) induced diabetic rats. Methods The male Wistar albino rats were randomly divided into four groups of eight animals each: Control group (C), CM-treated control group (C+CMEE), Diabetic control group (D), CM- treated diabetic group (D+CMEE). Diabetes was induced by intraperitoneal injection of STZ (55 mg/kg/ bwt). After being confirmed the diabetic rats were treated with C. mukul gum resin ethanolic extract (CMEE) for 60 days. The biochemical estimations like antioxidant, oxidative stress marker enzymes and hepatic marker enzymes of tissues were performed. Results The diabetic rats showed increased level of enzymatic activities aspartate aminotransaminase (AST), alanine aminotransaminase (ALT) in liver and kidney and oxidative markers like lipid peroxidation (LPO) and protein oxidation (PO) in pancreas and heart. Antioxidant enzyme activities were significantly decreased in the pancreas and heart compared to control group. Administration of CMEE (200 mg/kg bw) to diabetic rats for 60 days significantly reversed the above parameters towards normalcy. Conclusions In conclusion, our data indicate the preventive role of C. mukul against STZ-induced diabetic oxidative stress; hence this plant could be used as an adjuvant therapy for the prevention and/or management of diabetes and aggravated antioxidant status. PMID:23569867

  7. Effect of chronic ethanol (EtOH) and aging on drug metabolism in F-344 male rats

    SciTech Connect

    Galinsky, R.E.; Johnson, D.H.; Kimura, R.E.; Franklin, M.R. )

    1989-02-09

    The effects of chronic ethanol on in vitro and in vivo drug metabolism were examined in 6 and 25 month old male Fischer 344 rats. Animals were divided into three diet groups: (1) Diet containing EtOH, (2) pair-fed controls and (3) rat chow ad lib. Rats in groups 1 and 2 were fed 3 times daily for six weeks via permanent gastrostomy and received EtOH at doses of 5-8 g/kg/day in the first 3 weeks and 12 g/kg/day for the last 3 weeks. Total caloric intake was 90-120 kcal/kg/day. After 6 weeks, the pharmacokinetics of i.v. acetaminophen (A), 30 mg/kg, were examined to probe in vivo drug conjugation. There was no effects of EtOH on the total CL of A in young or old rats. The fraction of the dose recovered in the urine as A-glucuronide and the partial clearance to A-glucuronide was increased by EtOH. There was no effect on the rate of A-sulfate formation. EtOH increased the renal clearance of A but not of A-sulfate or A-glucuronide. In vitro, EtOH increased hepatic cytochrome P-450 concentration and p-nitroanisole demethylase activity, especially in old rats where values returned to those seen in untreated young males. Erythromycin and ethylmorphine demethylase and p-nitrophenol hydroxylase activities were not increased by the EtOH treatment. EtOH increased UDP-glucuronosyltransferase activity towards 1-naphthol, but not towards morphine, estrone, or testosterone. EtOH had no effect on the cytosolic glutathione S-transferase (1-chloro-2,4-dinitrobenzene) and phenol sulfotransferase (p-nitrophenol) activities.

  8. Combining in silico protein stability calculations with structure-function relationships to explore the effect of polymorphic variation on cytochrome P450 drug metabolism.

    PubMed

    Arendse, Lauren; Blundell, Tom L; Blackburn, Jonathan

    2013-09-01

    We carried out an in silico structural analysis of 348 non-synonymous single nucleotide polymorphisms, found across nine of the major human drug metabolising cytochrome P450 isoforms, to determine the effects of mutations on enzyme structure and function. Previous functional studies in our group have delineated regions of the cytochrome P450 structure important for substrate recognition, substrate and product access and egress from the active site and interaction with the cytochrome P450 reductase. Here we combine the information from those studies with new in silico calculations on the effect of mutations on protein stability and we compare our results to experimental data in order to establish the likely causes of altered drug metabolism observed for cytochrome P450 variants in functional assays to date, in the process creating a cytochrome P450 polymorphic variant map. Using the computational tool Site Directed Mutator we predicted destabilising mutations that result in altered enzyme function in vitro with a specificity of 83%. We found that 75% of all cytochrome P450 mutations that show altered activity in vitro are either predicted to be destabilising to protein structure or are found within regions predicted to be important for catalytic activity. Furthermore, we found that 70% of the mutations that showed similar activity to the wild-type enzyme in in vitro studies lie outside of functional regions important for catalytic activity and are predicted to have no effect on protein stability. Our resultant cytochrome P450 polymorphic variant map should therefore find utility in predicting the likely functional effect of uncharacterised variants on drug metabolism.

  9. Temperature modulates hepatic carbohydrate metabolic enzyme activity and gene expression in juvenile GIFT tilapia (Oreochromis niloticus) fed a carbohydrate-enriched diet.

    PubMed

    Qiang, J; He, J; Yang, H; Wang, H; Kpundeh, M D; Xu, P; Zhu, Z X

    2014-02-01

    The effects of rearing temperature on hepatic glucokinase (GK), glucose-6-phosphatase (G6Pase) and Glucose-6-phosphate dehydrogenase (G6PD) activity and gene expression were studied in GIFT (genetically improved farmed tilapia) tilapia fed a high carbohydrate diet containing 28% crude protein, 5% crude lipid and 40% wheat starch. Triplicate groups of fish (11.28 g initial body weight) were fed the diet for 45 days at 22 °C, 28 °C or 34 °C. At the end of the trial, final body weight of juvenile at 28 °C (59.12 g) was higher than that of the fish reared at 22 °C (27.13 g) and 34 °C (43.17 g). Feed intake, feed efficiency and protein efficiency ratio were also better at 28 °C. Liver glycogen levels were higher at 28 °C, while plasma glucose levels were higher in the 22 °C group. Significant (P<0.05) effects of water temperature on enzymes activities and gene expression were observed. Hepatic GK activity and mRNA level were higher at 28 °C than at 34 °C. Higher G6Pase and G6PD activity and gene expression were observed at 22 °C. Overall, the data show that juveniles reared at 28 °C exhibited enhanced liver glycolytic capacity. In contrast, hepatic gluconeogenesis and lipogenesis were increased by low temperature (22 °C).

  10. An evaluation of hepatic enzyme elevations among HIV-infected released prisoners enrolled in two randomized placebo-controlled trials of extended release naltrexone.

    PubMed

    Vagenas, Panagiotis; Di Paola, Angela; Herme, Maua; Lincoln, Thomas; Skiest, Daniel J; Altice, Frederick L; Springer, Sandra A

    2014-07-01

    Extended-release naltrexone (XR-NTX), an approved treatment for opioid or alcohol dependence, is a once-monthly injectable formulation of naltrexone. Hepatotoxicity concerns have limited its use, necessitating further investigation. This study aims to examine hepatic enzyme levels in participants of 2 randomized placebo-controlled trials (RCTs) of XR-NTX. Hepatic transaminases were measured in 85 patients enrolled in RCTs of XR-NTX among HIV-infected prisoners, transitioning to the community and receiving treatment for either dependence on alcohol (52.9%), opioids (44.7%) or both (16.5%). Baseline characteristics included HCV co-infection (55.7%), antiretroviral therapy (81%), mental illness (39%) and receiving psychiatric medications (34.1%). Levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma glutamyl transferase (GGT) were not statistically different between persons randomized to placebo (N=24) and XR-NTX (N=61) arms. These results confirm that XR-NTX is safe to use among opioid and alcohol dependent HIV-infected released prisoners receiving ART with high rates of co-morbid HCV infection and mental illness.

  11. Pituitary-dependent masculinization of hepatic hexobarbital hydroxylase in Crl:CD-1(ICR)BR mice.

    PubMed

    Shapiro, B H

    1985-03-25

    The sexual dimorphism in hepatic drug metabolism found in Crl:CD-1 mice is due to the normally repressive effects of testicular androgens on the activities of hepatic monooxygenases. The ability of testosterone to elevate the Michaelis constant (Km) and reduce the maximum velocity (Vmax) of hepatic hexobarbital hydroxylase is dependent upon the pituitary, so that in the hypophysectomized mouse androgens have no repressive effects on the activities of hepatic monooxygenases.

  12. Effects of selenium dietary enhancement on hatchery-reared coho salmon, Oncorhynchus kisutch (Walbaum), when compared with wild coho: hepatic enzymes and seawater adaptation evaluated.

    USGS Publications Warehouse

    Felton, S.P.; Landolt, M.L.; Grace, R.; Palmisano, A.N.

    1996-01-01

    Hatchery-reared coho salmon, Oncorhynchus kisutch (Walbaum), were fed elevated levels of selenium (as Na2SeO3) to raise eviscerated body burdens to the level measured in wild counterparts. The goal was to find a dietary concentration that would achieve the desired effect without causing damage to growth and normal development. To measure some indices of health, the detoxifying enzymes chosen were hepatic glutathione peroxidase (GSH-Px) and hepatic superoxide dismutase (SOD). Eviscerated body selenium (Se) concentration, GSH-Px and SOD levels were measured during and at the end of the 9 month freshwater feeding trial. Selenium retention and enzyme activity were also measured during 6 months’residence in sea water (SW). Selenium supplements were added to a commercial ration to give final concentrations of 1.1, 8.6, 11.1, 13.6 μg g-1 Se in the four respective diets. The results indicated that a dietary concentration of 8.6 μg g-1selenium was capable of inducing eviscerated body burdens similar to those found in wild fish. The elevated selenium levels persisted throughout the freshwater (FW) rearing phase, but declined when the fish were fed an unsupplemented ration upon SW entry. Superoxide dismutase levels did not increase above control levels. Glutathione peroxidase levels increased in fish fed the supplemented diets. GSH-Px activity declined in the higher supplemented dietary groups when all groups were reduced to the control group level of 1.1 μg g-1. Cumulative mortality in SW was 20% in fish fed either the 1.1 or the 8.6 μg g-1 Se diets. The 8.6 μg g-1 Se supplemented diets did produce healthy coho, comparable to their wild counterparts.

  13. Effects of cigarette smoke and dietary vitamin E levels on selected lung and hepatic biotransformation enzymes in mice

    SciTech Connect

    Graziano, M.J.; Gairola, C.; Dorough, H.W.

    1985-01-01

    Young male C57BL mice were exposed nose-only to cigarette smoke 20 min/day for 8 weeks while maintained on diets containing 0, 5, and 100 ppm of vitamin E. Smoking had no effect on hepatic aryl hydrocarbon hydroxylase (AHH), UDP-glucuronyltransferase, glutathione S-transferase, parathion desulfurase, or parathion esterase activity. Lung AHH activity was increased in all smoke-exposed mice, although the increase was significantly less in animals maintained on the vitamin E-free diet. All mice on the vitamin E-free diet showed reduced lung AHH activity and increased hepatic lipid peroxidation. No other biotransformations tested were significantly altered by varying vitamin E concentrations alone or in combination with cigarette smoke. For all vitamin E diets, both the smoke-exposed and sham-treated mice gained significantly less weight than the control animals. This effect was attributed to stress induced by restraint of the animals within the smoking apparatus. The results of these experiments show that both cigarette smoke and vitamin E-deficient diets may affect xenobiotic metabolism but that the combination does not appear to alter markedly their individual effects or to induce ones not previously observed.

  14. Rifampicin, a keystone inducer of drug metabolism: from Herbert Remmer's pioneering ideas to modern concepts.

    PubMed

    Bolt, Hermann M

    2004-10-01

    In 1972, Herbert Remmer's group at the University of Tübingen had developed a micro method to assess cytochrome P450 contents and activities of drug metabolising enzymes in needle biopsies from human liver. Upon application of this method to patients receiving different kinds of drug therapy, Herbert Remmer was the first to describe that total human hepatic cytochrome P450 was markedly elevated by the new anti-tuberculosis drug rifampicin. Similar observations were made for the antimycotic clotrimazol. In 1975, Herbert Remmer's group described the unique species difference that induction of cytochrome P450 by rifampicin did not occur in the rat. After the first clinical reports of impaired effectiveness of oral contraception in persons treated with rifampicin, studies at Herbert Remmer's Institute showed a 4-fold increase, after repetitive rifampicin administration to humans, in the ability of hepatic microsomes to ortho-hydroxylate the contraceptive estrogen ethinylestradiol, compared to microsomes from untreated normal subjects. Subsequent pharmacokinetic investigations were compatible with this induction of the estrogen-2-hydroxylase by rifampicin and provided a rational explanation for the classical drug interaction between rifampicin and oral contraceptives. These early studies, in the 1970s in Tübingen, were followed by further developments. It was realized that the cytochrome P450 isoenzyme 3A4 (CYP3A4) is the major CYP isozyme in the human liver metabolizing a variety of xenobiotics and endobiotics, being also responsible for the 2-hydroxylation of ethinylestradiol. The inducibility of CYP3A4 by barbiturates and rifampicin explains the effects of inducers to enhance the clearance of ethynylestradiol and thereby to reduce the effectiveness of oral contraceptives, rifampicin being one of the most potent inducers of human CYP3A4 gene expression. Since 1998, novel "orphan" members of the nuclear hormone receptor superfamily were cloned from mouse, rat, rabbit

  15. Does an extract of carob (Ceratonia siliqua L.) have chemopreventive potential related to oxidative stress and drug metabolism in human colon cells?

    PubMed

    Klenow, Stefanie; Jahns, Franziska; Pool-Zobel, Beatrice L; Glei, Michael

    2009-04-08

    Phenolic ingredients of an aqueous carob extract are well characterized and consist of mainly gallic acid (GA). In order to assess possible chemopreventive mechanisms of carob, which can be used as a cacao substitute, effects on expression of genes related to stress response and drug metabolism were studied using human colon cell lines of different transformation state (LT97 and HT29). Stress-related genes, namely catalase (CAT) and superoxide dismutase (SOD2), were induced by carob extract and GA in LT97 adenoma, but not in HT29 carcinoma cells. Although corresponding protein products and enzyme activities were not elevated, pretreatment with carob extract and GA for 24 h reduced DNA damage in cells challenged with hydrogen peroxide (H(2)O(2)). In conclusion, carob extract and its major phenolic ingredient GA modulate gene expression and protect colon adenoma cells from genotoxic impact of H(2)O(2). Upregulation of stress-response genes could not be related to functional consequences.

  16. Development of stably transfected human and rat hepatoma cell lines for the species-specific assessment of xenobiotic response enhancer module (XREM)-dependent induction of drug metabolism.

    PubMed

    Fery, Yvonne; Mueller, Stefan O; Schrenk, Dieter

    2010-11-09

    Based on our current knowledge, PXR holds a key position in the induction of a selective battery of enzymes and transporters of drug metabolism. In order to prevent serious adverse drug effects or unpredicted drug-drug interactions (DDI), it is compulsory to investigate the possible inducing potency of drugs under development. Furthermore, analysis of the inducing potency of environmental pollutants and new or manufactured chemicals is part of toxicological risk assessment. In non-transfected human HepG2 and rat H4IIE hepatoma cells, we examined the characteristics of expression of 45 genes involved in drug metabolism. A few gene products such as CYP2B6 or CYP3A4 mRNA were prominent in HepG2 cells while their major rat counterparts were, e.g., CYP2B3 or CYP3A1/3A3. Furthermore, a number of xenobiotic receptors including PXR were expressed in both cell lines. A number of genes were regulated in a cell type and species-specific manner after incubation with the prototypical PXR agonists rifampicin or dexamethasone, respectively. Then, we established cell-based reporter gene assays for screening for PXR-dependent induction of drug metabolism. HepG2 and H4IIE cells were stably transfected with a reporter gene containing PXR responsive elements (XREMs) which mediate the induction of PXR target genes such as CYP3A enzymes. With both stable cell lines the CYP inducers clotrimazole, dexamethasone, omeprazole, phenobarbital, rifampicin, as well as the drug candidate EMD 392949 and the brominated flame retardants hexabromocylododecane (HBCD) and a pentabromodiphenyl ether (pentaBDE) mixture were screened. In the human HepG2-XREM3 and rat H4IIE-XREM3 cells, clotrimazole and HBCD were found as common activators of the human and rat PXR whereas pentaBDE was more effective with the human cell system. Omeprazole and phenobarbital did not induce the rat PXR-dependent reporter gene expression in H4IIE-XREM3 cells, while a moderate increase was found in HepG2-XREM3 cells. EMD 392949

  17. A competitive enzyme-linked immunosorbent assay specific for murine hepcidin-1: correlation with hepatic mRNA expression in established and novel models of dysregulated iron homeostasis.

    PubMed

    Gutschow, Patrick; Schmidt, Paul J; Han, Huiling; Ostland, Vaughn; Bartnikas, Thomas B; Pettiglio, Michael A; Herrera, Carolina; Butler, James S; Nemeth, Elizabeta; Ganz, Tomas; Fleming, Mark D; Westerman, Mark

    2015-02-01

    Mice have been essential for distinguishing the role of hepcidin in iron homeostasis. Currently, investigators monitor levels of murine hepatic hepcidin-1 mRNA as a surrogate marker for the bioactive hepcidin protein itself. Here, we describe and validate a competitive, enzyme-linked immunosorbent assay that quantifies hepcidin-1 in mouse serum and urine. The assay exhibits a biologically relevant lower limit of detection, high precision, and excellent linearity and recovery. We also demonstrate correlation between serum and urine hepcidin-1 values and validate the competitive enzyme-linked immunosorbent assay by analyzing plasma hepcidin response of mice to physiological challenges, including iron deficiency, iron overload, acute blood loss, and inflammation. Furthermore, we analyze multiple murine genetic models of iron dysregulation, including β-thalassemia intermedia (Hbb(th3/+)), hereditary hemochromatosis (Hfe(-/-), Hjv(-/-), and Tfr2(Y245X/Y245X)), hypotransferrinemia (Trf(hpx/hpx)), heterozygous transferrin receptor 1 deficiency (Tfrc(+/-)) and iron refractory iron deficiency anemia (Tmprss6(-/-) and Tmprss6(hem8/hem8)). Novel compound iron metabolism mutants were also phenotypically characterized here for the first time. We demonstrate that serum hepcidin concentrations correlate with liver hepcidin mRNA expression, transferrin saturation and non-heme liver iron. In some circumstances, serum hepcidin-1 more accurately predicts iron parameters than hepcidin mRNA, and distinguishes smaller, statistically significant differences between experimental groups.

  18. Modulatory effect of green tea extract on hepatic key enzymes of glucose metabolism in streptozotocin and high fat diet induced diabetic rats.

    PubMed

    Sundaram, Ramalingam; Naresh, Rajendran; Shanthi, Palanivelu; Sachdanandam, Panchanatham

    2013-05-15

    The study was undertaken to evaluate the antidiabetic effect of green tea extract on carbohydrate metabolic key enzymes in control and streptozotocin high fat diet -induced diabetic rats. The daily oral treatment of green tea extract (300 mg/kg body weight) to diabetic rats for 30 days resulted in a significant reduction in the levels of plasma glucose, glycosylated hemoglobin (HbA1c) and increase in the levels of insulin and hemoglobin. The altered activities of the key enzymes of carbohydrate metabolism such as hexokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, glucose-6-phosphate dehydrogenase, glycogen synthase and glycogen phosphorylase in liver of diabetic rats were significantly reverted to near normal levels by the administration of green tea extract. Further, green tea extract administration to diabetic rats improved muscle and hepatic glycogen content suggesting the antihyperglycemic potential of green tea extract in diabetic rats. The obtained results were compared with metformin, a standard oral hypoglycemic drug. Thus, this study indicates that the administration of green tea extract to diabetic rats resulted in alterations in the metabolism of glucose with subsequent reduction in plasma glucose levels.

  19. Effect of ketogenic diet on nucleotide hydrolysis and hepatic enzymes in blood serum of rats in a lithium-pilocarpine-induced status epilepticus.

    PubMed

    da Silveira, Vanessa Gass; de Paula Cognato, Giana; Müller, Alexandre Pastoris; Figueiró, Fabrício; Bonan, Carla Denise; Perry, Marcos L Santos; Battastini, Ana Maria Oliveira

    2010-06-01

    The ketogenic diet (KD) is a high-fat and low-carbohydrate diet, used for treating refractory epilepsy in children. We have previously shown alterations in nucleotidase activities from the central nervous system and blood serum of rats submitted to different models of epilepsy. In this study we investigated the effect of KD on nucleotidase activities in the blood serum, as well if KD has any influence in the activity of liver enzymes such as alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase activities in Wistar rats submitted to the lithium-pilocarpine model of epilepsy. At 21 days of age, rats received an injection of lithium chloride and, 18-19 h later, they received an injection of pilocarpine hydrochloride for status epilepticus induction. The results reported herein show that seizures induced by lithium-pilocarpine elicit a significant increase in ATP hydrolysis and alkaline phosphatase activity, as well as a decrease in ADP hydrolysis and aspartate aminotransferase activity. The KD is a rigorous regimen that can be associated with hepatic damage, as shown herein by the elevated activities of liver enzymes and 5'-nucleotidase in blood serum. Further studies are necessary to investigate the mechanism of inhibition of lithium on nucleotidases in blood serum.

  20. Novel six-nucleotide deletion in the hepatic fructose-1,6-bisphosphate aldolase gene in a patient with hereditary fructose intolerance and enzyme structure-function implications.

    PubMed

    Santamaria, R; Vitagliano, L; Tamasi, S; Izzo, P; Zancan, L; Zagari, A; Salvatore, F

    1999-01-01

    Hereditary fructose intolerance (HFI) is an autosomal recessive human disease that results from the deficiency of the hepatic aldolase isoenzyme. Affected individuals will succumb to the disease unless it is readily diagnosed and fructose eliminated from the diet. Simple and non-invasive diagnosis is now possible by direct DNA analysis that scans for known and unknown mutations. Using a combination of several PCR-based methods (restriction enzyme digestion, allele specific oligonucleotide hybridisation, single strand conformation analysis and direct sequencing) we identified a novel six-nucleotide deletion in exon 6 of the aldolase B gene (delta 6ex6) that leads to the elimination of two amino acid residues (Leu182 and Val183) leaving the message inframe. The three-dimensional structural alterations induced in the enzyme by delta 6ex6 have been elucidated by molecular graphics analysis using the crystal structure of the rabbit muscle aldolase as reference model. These studies showed that the elimination of Leu182 and Val183 perturbs the correct orientation of adjacent catalytic residues such as Lys146 and Glu187.

  1. Do Antioxidant Enzymes and Glutathione Play Roles in the Induction of Hepatic Oxidative Stress in Mice upon Subchronic Exposure to Mixtures of Dichloroacetate and Trichloroacetate?

    PubMed Central

    Hassoun, Ezdihar; Cearfoss, Jacquelyn

    2014-01-01

    Dichloroacetate (DCA) and trichloroacetate (TCA) are water chlorination byproducts, and their mixtures were previously found to induce additive to greater than additive effects on hepatic oxidative stress (OS) induction in mice after subchronic exposure. To investigate the roles of antioxidant enzymes and glutathione (GSH) in those effects, livers of B6C3F1 mice treated by gavage with 7.5, 15, or 30 mg DCA/kg/day, 12.5, 25, or 50 mg TCA/kg/day, and mixtures (Mix I, Mix II and Mix III) at DCA:TCA ratios corresponding to 7.5:12.5, 15:25 and 25:50 mg/kg/day, respectively, for 13 weeks. Livers were assayed for superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), as well as for GSH levels. In general, DCA suppressed SOD and GSH-Px activities and GSH levels but caused no changes in CAT activity; TCA increased SOD and CAT activities, suppressed GSH-Px activity, but did not change GSH levels; mixtures of DCA and TCA increased SOD and CAT activities and suppressed GSH-Px activity and GSH levels. In conclusion, antioxidant enzymes contribute to DCA-, TCA- and mixtures-induced OS, but not to changes from additive to greater than additive effects produced by different mixture compositions of the compounds. GSH on the hand may contribute to these changes. PMID:25530655

  2. Chokeberry (Aronia melanocarpa) juice modulates 7,12-dimethylbenz[a]anthracene induced hepatic but not mammary gland phase I and II enzymes in female rats.

    PubMed

    Szaefer, Hanna; Krajka-Kuźniak, Violetta; Ignatowicz, Ewa; Adamska, Teresa; Baer-Dubowska, Wanda

    2011-03-01

    Chokeberry is a rich source of procyanidins known to have several types of biological activity including anticarcinogenic potential in experimental models. In this study we examined the effect of chokeberry juice on the hepatic and mammary gland carcinogen metabolizing enzyme expression altered by the polycyclic aromatic hydrocarbon, 7,12-dimethylbenz[a]anthracene (DMBA). Sprague-Dawley rats were gavaged with chokeberry juice (8 ml/kg b.w.) for 28 consecutive days. DMBA was administered i.p. on the 27th and the 28th days. Pretreatment with chokeberry juice reduced the activity of CYP1A1 and increased that of CYP2B involved in metabolic activation/detoxication of DMBA in rat liver, as well as expression and activity of phase II enzymes. Chokeberry juice had no effect on these parameters in the mammary gland and DMBA induced DNA damage in rat blood cells. These results together with our earlier observations indicate that metabolic alterations induced by chokeberry feeding are tissue specific and depend on the class of carcinogen.

  3. Quercetin induces hepatic γ-glutamyl hydrolase expression in rats by suppressing hepatic microRNA rno-miR-125b-3p.

    PubMed

    Wein, Silvia Anette; Laviano, Alessandro; Wolffram, Siegfried

    2015-12-01

    Exogenous factors such as food components including the flavonoid quercetin are suspected to influence micro RNA (miRNA) concentrations and thus possibly target enzymes involved in xenobiotic metabolism. This study therefore investigates the influence of orally administered quercetin on hepatic miRNA and the identification of enzyme target mRNAs relevant in drug metabolism. Male Wistar rats (n=16) were fed either a diet without (C) or with (Q) the addition of 100-ppm quercetin for 7 weeks and subsequently euthanized at the end of the dark phase. To avoid strong effects of food deprivation on hepatic metabolism, food was not removed until 5 h prior to the procedure. Liver was immediately dissected and snap-frozen in liquid nitrogen. Concentrations of 352 hepatic miRNA were measured in pool samples of each dietary group (n=8) using the RT(2) miRNA PCR Array System. Differential expression of miRNAs was assumed with fold changes ≥3. Target genes of differentially expressed miRNAs were identified using the database TargetScan. Because rno-miR-125b-3p showed the most prominent fold-change (-9) we further analyzed the expression of its top predicted target gene gamma-glutamyl hydrolase (GGH) by quantitative real-time PCR using hypoxanthine phosphoribosyltransferase 1 (hprt1) as endogenous control. Compared to controls, 23 miRNAs were differentially expressed in rats fed quercetin. A ninefold reduction in hepatic miRNA rno-miR-125b-3p was paralleled by significant induction of GGH mRNA in liver of quercetin fed rats. Because increased GGH expressions were repeatedly associated with resistance to methotrexate, concomitant intake with quercetin should be monitored carefully.

  4. Effect of standardized cranberry extract on the activity and expression of selected biotransformation enzymes in rat liver and intestine.

    PubMed

    Bártíková, Hana; Boušová, Iva; Jedličková, Pavla; Lněničková, Kateřina; Skálová, Lenka; Szotáková, Barbora

    2014-09-18

    The use of dietary supplements containing cranberry extract is a common way to prevent urinary tract infections. As consumption of these supplements containing a mixture of concentrated anthocyanins and proanthocyanidins has increased, interest in their possible interactions with drug-metabolizing enzymes has grown. In this in vivo study, rats were treated with a standardized cranberry extract (CystiCran®) obtained from Vaccinium macrocarpon in two dosage schemes (14 days, 0.5 mg of proanthocyanidins/kg/day; 1 day, 1.5 mg of proanthocyanidins/kg/day). The aim of this study was to evaluate the effect of anthocyanins and proanthocyanidins contained in this extract on the activity and expression of intestinal and hepatic biotransformation enzymes: cytochrome P450 (CYP1A1, CYP1A2, CYP2B and CYP3A), carbonyl reductase 1 (CBR1), glutathione-S-transferase (GST) and UDP-glucuronosyl transferase (UGT). Administration of cranberry extract led to moderate increases in the activities of hepatic CYP3A (by 34%), CYP1A1 (by 38%), UGT (by 40%), CBR1 (by 17%) and GST (by 13%), while activities of these enzymes in the small intestine were unchanged. No changes in the relative amounts of these proteins were found. Taken together, the interactions of cranberry extract with simultaneously administered drugs seem not to be serious.

  5. Physiogenomic analysis of CYP450 drug metabolism correlates dyslipidemia with pharmacogenetic functional status in psychiatric patients

    PubMed Central

    Ruaño, Gualberto; Villagra, David; Szarek, Bonnie; Windemuth, Andreas; Kocherla, Mohan; Gorowski, Krystyna; Berrezueta, Christopher; Schwartz, Harold I; Goethe, John

    2011-01-01

    Aims To investigate associations between novel human cytochrome P450 (CYP450) combinatory (multigene) and substrate-specific drug metabolism indices, and elements of metabolic syndrome, such as low density lipoprotein cholesterol (LDLc), high density lipoprotein cholesterol (HDLc), triglycerides and BMI, using physiogenomic analysis. Methods CYP2C9, CYP2C19 and CYP2D6 genotypes and clinical data were obtained for 150 consecutive, consenting hospital admissions with a diagnosis of major depressive disorder and who were treated with psychotropic medications. Data analysis compared clinical measures of LDLc, HDLc, triglyceride and BMI with novel combinatory and substrate-specific CYP450 drug metabolism indices. Results We found that a greater metabolic reserve index score is related to lower LDLc and higher HDLc, and that a greater metabolic alteration index score corresponds with higher LDLc and lower HLDc values. We also discovered that the sertraline drug-specific indices correlated with cholesterol and triglyceride values. Conclusions Overall, we demonstrated how a multigene approach to CYP450 genotype analysis yields more accurate and significant results than single-gene analyses. Ranking the individual with respect to the population represents a potential tool for assessing risk of dyslipidemia in major depressive disorder patients who are being treated with psychotropics. In addition, the drug-specific indices appear useful for modeling a variable of potential relevance to an individual’s risk of drug-related dyslipidemia. PMID:21861666

  6. Hepatocyte nuclear factor 4α regulation of bile acid and drug metabolism

    PubMed Central

    Chiang, John YL

    2013-01-01

    The hepatocyte nuclear factor 4α (HNF4α) is a liver-enriched nuclear receptor that plays a critical role in early morphogenesis, fetal liver development, liver differentiation and metabolism. Human HNF4α gene mutations cause maturity on-set diabetes of the young type 1, an autosomal dominant non-insulin-dependent diabetes mellitus. HNF4α is an orphan nuclear receptor because of which the endogenous ligand has not been firmly identified. The trans-activating activity of HNF4α is enhanced by interacting with co-activators and inhibited by corepressors. Recent studies have revealed that HNF4α plays a central role in regulation of bile acid metabolism in the liver. Bile acids are required for biliary excretion of cholesterol and metabolites, and intestinal absorption of fat, nutrients, drug and xenobiotics for transport and distribution to liver and other tissues. Bile acids are signaling molecules that activate nuclear receptors to control lipids and drug metabolism in the liver and intestine. Therefore, HNF4α plays a central role in coordinated regulation of bile acid and xenobiotics metabolism. Drugs that specifically activate HNF4α could be developed for treating metabolic diseases such as diabetes, dyslipidemia and cholestasis, as well as drug metabolism and detoxification. PMID:19239393

  7. Dietary chia seed induced changes in hepatic transcription factors and their target lipogenic and oxidative enzyme activities in dyslipidaemic insulin-resistant rats.

    PubMed

    Rossi, Andrea S; Oliva, Maria E; Ferreira, Maria R; Chicco, Adriana; Lombardo, Yolanda B

    2013-05-01

    The present study analyses the effect of dietary chia seed rich in n-3 α-linolenic acid on the mechanisms underlying dyslipidaemia and liver steatosis developed in rats fed a sucrose-rich diet (SRD) for either 3 weeks or 5 months. The key hepatic enzyme activities such as fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), glucose-6-phosphate dehydrogenase (G-6-PDH), carnitine palmitoyltransferase-1 (CPT-1) and fatty acid oxidase (FAO) involved in lipid metabolism and the protein mass levels of sterol regulatory element-binding protein-1 (SREBP-1) and PPARα were studied. (1) For 3 weeks, Wistar rats were fed either a SRD with 11 % of maize oil (MO) as dietary fat or a SRD in which chia seed replaced MO (SRD+Chia). (2) A second group of rats were fed a SRD for 3 months. Afterwards, half the rats continued with the SRD while for the other half, MO was replaced by chia for 2 months (SRD+Chia). In a control group, maize starch replaced sucrose. Liver TAG and the aforementioned parameters were analysed in all groups. The replacement of MO by chia in the SRD prevented (3 weeks) or improved/normalised (5 months) increases in dyslipidaemia, liver TAG, FAS, ACC and G-6-PDH activities, and increased FAO and CPT-1 activities. Protein levels of PPARα increased, and the increased mature form of SREBP-1 protein levels in the SRD was normalised by chia in both protocols (1 and 2). The present study provides new data regarding some key mechanisms related to the fate of hepatic fatty acid metabolism that seem to be involved in the effect of dietary chia seed in preventing and normalising/improving dyslipidaemia and liver steatosis in an insulin-resistant rat model.

  8. The changing environment of graduate and postdoctoral training in drug metabolism: viewpoints from academia, industry, and government.

    PubMed

    Stevens, Jeffrey C; Dean, Dennis C; Preusch, Peter C; Correia, Maria Almira

    2003-04-01

    This article is an invited report of a symposium sponsored by the Drug Metabolism Division of the American Society for Pharmacology and Experimental Therapeutics held at Experimental Biology 2002 in New Orleans. The impetus for the symposium was a perceived shortage in the supply of graduate students qualified for drug metabolism research positions in industry, academia, and government. For industry, recent hiring stems largely from the expansion of drug metabolism departments in an effort to keep pace with the demands of drug discovery and new technologies. In turn, regulatory scientists are needed to review and verify the results of the increased number and volume of studies required for drug development and approval. Thus the initial source of training, academia, has been forced to recognize these external hiring pressures while trying to attract and retain the faculty, postdoctoral scientists, and students necessary for active teaching and research programs. The trend of the expansion of the interdisciplinary nature of traditional drug metabolism to include emerging technologies such as pharmacogenetics, transporters, and proteomics and the implications for future needs in training and funding were acknowledged. There was also consensus on the value of partnerships between academia and industry for increasing student interest and providing training in disciplines directly applicable to industrial drug metabolism research. Factors affecting the sources of these trainees, such as federal funding, the number of trainees per institution, and recent issues with immigration restrictions that have limited the flow of scientists were also discussed.

  9. Hepatitis B

    MedlinePlus

    ... Home » Hepatitis B » Hepatitis B Entire Lesson Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... Enter ZIP code here Enter ZIP code here Hepatitis B Entire Lesson for Veterans and the Public ...

  10. Hepatic uptake and storage of warfarin. The relation with the target enzyme vitamin K 2,3-epoxide reductase

    SciTech Connect

    Thijssen, H.H.; Baars, L.G.

    1987-12-01

    The mechanisms of the reported dose-dependent warfarin pharmacokinetics were investigated using (/sup 14/C)warfarin. When administered in microdoses (9 micrograms i.v.) to rats (male Wistars, 270-300 g), a steep distribution phase (T1/2 = 0.25 hr) was followed by a relatively slow beta-phase (T1/2 = 40 hr). The observed volume of distribution was 390 ml. This pharmacokinetic behavior contrasted highly with the one seen for higher (greater than 0.2 mg/kg) doses (unlabeled) warfarin; volume of distribution = 45 ml, T1/2 = 12.5 hr. If a macrodose (0.2 mg/kg) preceded (16 hr) the microdose, normal pharmacokinetics were observed for the latter, suggesting a saturable deep compartment. The administration of 4-hydroxycoumarins (i.e., acenocoumarol, phenprocoumon and warfarin) after the microdose of (/sup 14/C)warfarin was in its beta-phase caused a rapid rise of plasma (/sup 14/C)warfarin indicating (/sup 14/C)warfarin to be displaced from the deep compartment. The rate of appearance of (/sup 14/C)warfarin was 0.3 hr-1 irrespective the 4-hydroxycoumarin used. The hepatic distribution of (/sup 14/C)warfarin was investigated and the effect of a displacer thereupon. Fifty-three hours after the (/sup 14/C)warfarin administration, the liver contained about 40% of the dose; 45% of it was bound to microsomes. The administration of acenocoumarol (0.2 mg/kg) at 48 hr, halved the liver content. (/sup 14/C)warfarin was redistributed from microsomes (-65%) and from the 10,000 X g pellet (-65%) into the cytosol (+260%) and the plasma (+320%). Microsomal bound (/sup 14/C)warfarin in vitro could not be washed out or be displaced unless dithiothreitol (50 mM) was included in the washing buffers.

  11. Significant interspecies differences in induction profiles of hepatic CYP enzymes by TCDD in bank and field voles.

    PubMed

    Murtomaa-Hautala, Mari; Korkalainen, Merja; Pelkonen, Olavi; Hegde, Nagabhooshan; Pohjanvirta, Raimo; Huitu, Otso; Henttonen, Heikki; Rautio, Arja; Viitala, Pirkko; Viluksela, Matti

    2012-03-01

    The gene expression and induction of cytochrome P450 (CYP)-enzymes following 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) peroral administration was studied in the livers of two wild vole species--the bank vole (Myodes glareolus) and the field vole (Microtus agrestis). The dioxin-sensitive C57BL/6 mouse was used as a reference. Doses of 0.05, 0.5, 5.0, and 50 µg/kg were applied to ascertain a dose-response relationship, and the dose of 50 µg/kg was applied to the study time course for up to 96 h. The cytochrome P450 1A1 (CYP1A1) mRNA expression showed an expected dose-dependent increase equally in both vole species. Bank voles expressed notably higher CYP2A mRNA levels as compared with field voles. Both species exhibited dose-dependent increases in putative CYP1A-, CYP2B-, and CYP2A-associated activities as measured by fluorometric assays for ethoxyresorufin-O-deethylase (EROD), penthoxyresorufin-O-depenthylase (PROD), and 7-ethoxycoumarin-O-deethylase (ECOD), respectively. Putative CYP2A-associated coumarin-7-hydroxylase (COH) activity showed a slight increase at the two highest doses of TCDD in field voles but not in bank voles, and their basal COH activity was only one-fourth or less of that in field voles. Overall, however, bank voles tended to exhibit higher CYP-associated enzyme activities measured at the two largest doses of TCDD than field voles. A western blot analysis of aryl hydrocarbon receptor (AhR) revealed that the two vole species had differential band patterns, suggesting dissimilar structures for their AhRs.

  12. Effects of Urtica dioica supplementation on blood lipids, hepatic enzymes and nitric oxide levels in type 2 diabetic patients: A double blind, randomized clinical trial

    PubMed Central

    Amiri Behzadi, Alidad; Kalalian-Moghaddam, Hamid; Ahmadi, Amir Hossein

    2016-01-01

    Objective: Oxidative stress plays an important role in the development of diabetic complications including metabolic abnormality-induced diabetic micro-vascular and macro-vascular complications. Urtica dioica L. (U. dioica) has been traditionally used in Iranian medicine as an herbal remedy for hypoglycemic or due to its anti-inflammatory properties. The aim of the present study was to evaluate the effects of hydro-alcoholic extract of U. dioica on blood lipids, hepatic enzymes and nitric oxide levels in patients with type 2 diabetes mellitus. Materials and Methods: 50 women with type 2 diabetes participated in this study and were randomly divided into two groups namely, control and intervention groups. Control group received placebo and intervention group received hydro-alcoholic extract of U. dioica. Before and after 8 weeks of continuous treatment, some biochemical serum levels including FPG, TG, SGPT, SGOT, HDL, LDL, SOD and NO were measured. Results: The results indicated that after 8 weeks, in the intervention group, FPG, TG, and SGPT levels significantly decreased and HDL, NO and SOD levels significantly increased as compared to the control group. Conclusion: Our results encourage the use of hydro-alcoholic extract of U. dioica as an antioxidant agent for additional therapy of diabetes as hydro-alcoholic extract of U. dioica may decrease risk factors of cardiovascular incidence and other complications in patients with diabetes mellitus. PMID:28078249

  13. The enzymes LSD1 and Set1A cooperate with the viral protein HBx to establish an active hepatitis B viral chromatin state

    PubMed Central

    Alarcon, Valentina; Hernández, Sergio; Rubio, Lorena; Alvarez, Francisca; Flores, Yvo; Varas-Godoy, Manuel; De Ferrari, Giancarlo V.; Kann, Michael; Villanueva, Rodrigo A.; Loyola, Alejandra

    2016-01-01

    With about 350 million people chronically infected around the world hepatitis B is a major health problem. Template for progeny HBV synthesis is the viral genome, organized as a minichromosome (cccDNA) inside the hepatocyte nucleus. How viral cccDNA gene expression is regulated by its chromatin structure; more importantly, how the modulation of this structure impacts on viral gene expression remains elusive. Here, we found that the enzyme SetDB1 contributes to setting up a repressed cccDNA chromatin state. This repressive state is activated by the histone lysine demethylase-1 (LSD1). Consistently, inhibiting or reducing LSD1 levels led to repression of viral gene expression. This correlates with the transcriptionally repressive mark H3K9 methylation and reduction on the activating marks H3 acetylation and H3K4 methylation on viral promoters. Investigating the importance of viral proteins we found that LSD1 recruitment to viral promoters was dependent on the viral transactivator protein HBx. Moreover, the histone methyltransferase Set1A and HBx are simultaneously bound to the core promoter, and Set1A expression correlates with cccDNA H3K4 methylation. Our results shed light on the mechanisms of HBV regulation mediated by the cccDNA chromatin structure, offering new therapeutic targets to develop drugs for the treatment of chronically infected HBV patients. PMID:27174370

  14. The enzymes LSD1 and Set1A cooperate with the viral protein HBx to establish an active hepatitis B viral chromatin state.

    PubMed

    Alarcon, Valentina; Hernández, Sergio; Rubio, Lorena; Alvarez, Francisca; Flores, Yvo; Varas-Godoy, Manuel; De Ferrari, Giancarlo V; Kann, Michael; Villanueva, Rodrigo A; Loyola, Alejandra

    2016-05-13

    With about 350 million people chronically infected around the world hepatitis B is a major health problem. Template for progeny HBV synthesis is the viral genome, organized as a minichromosome (cccDNA) inside the hepatocyte nucleus. How viral cccDNA gene expression is regulated by its chromatin structure; more importantly, how the modulation of this structure impacts on viral gene expression remains elusive. Here, we found that the enzyme SetDB1 contributes to setting up a repressed cccDNA chromatin state. This repressive state is activated by the histone lysine demethylase-1 (LSD1). Consistently, inhibiting or reducing LSD1 levels led to repression of viral gene expression. This correlates with the transcriptionally repressive mark H3K9 methylation and reduction on the activating marks H3 acetylation and H3K4 methylation on viral promoters. Investigating the importance of viral proteins we found that LSD1 recruitment to viral promoters was dependent on the viral transactivator protein HBx. Moreover, the histone methyltransferase Set1A and HBx are simultaneously bound to the core promoter, and Set1A expression correlates with cccDNA H3K4 methylation. Our results shed light on the mechanisms of HBV regulation mediated by the cccDNA chromatin structure, offering new therapeutic targets to develop drugs for the treatment of chronically infected HBV patients.

  15. Dietary D-psicose, a C-3 epimer of D-fructose, suppresses the activity of hepatic lipogenic enzymes in rats.

    PubMed

    Matsuo, T; Baba, Y; Hashiguchi, M; Takeshita, K; Izumori, K; Suzuki, H

    2001-01-01

    D-Psicose (D-ribo-2-hexulose), a C-3 epimer of D-fructose, is present in small quantities in commercial carbohydrate complexes or agricultural products. Wistar male rats were fed experimental diets which consisted of 5% D-psicose, cellulose, D-fructose or D-glucose for 28 days. Abdominal adipose tissue weight was significantly lower (P < 0.05) in rats fed the D-psicose diet than in rats fed a D-fructose and D-glucose diets, even though the four dietary groups were offered the same amount throughout the experimental period. Fatty acid synthase and glucose 6-phosphate dehydrogenase activities in the liver were significantly lower (P < 0.05) in rats fed the D-psicose diet than in rats fed the D-fructose and D-glucose diets. However, lipoprotein lipase activities in the heart, soleus muscle and perirenal adipose tissue were the same. These results suggest that a supplement of D-psicose in the diet suppresses hepatic lipogenic enzyme activities. The lower abdominal fat accumulation in rats fed a D-psicose diet might result from lower lipogenesis in the liver.

  16. The changes of serum testosterone level and hepatic microsome enzyme activity of crucian carp (Carassius carassius) exposed to a sublethal dosage of pentachlorophenol.

    PubMed

    Zhang, Min; Yin, Daqiang; Kong, Fanxiang

    2008-10-01

    Pentachlorophenol (PCP), which was reported to be a typical persistent organic pollutant and environmental endocrine disruptor, may cause threat to aquatic species. In this study, serum testosterone concentration, activity of liver microsome ethoxyresorufin O-deethylase (EROD) and glutathione S-transferases (GST) of crucian carp (Carassius carassius) exposed to PCP for 7 and 15 d, respectively, were examined. The results showed that testosterone concentration was induced remarkably after 7 d (P<0.05), and the testosterone concentrations in 15 d treatment crucian carp were higher than those in 7 d treatment. It was found that there were significant effects on activities of EROD and GST after crucian carp were exposed to PCP for 7 and 15 d (P<0.05), compared to the controls. EROD and GST activities increased with increase in PCP concentration and also with increase in time on exposure. The results indicated that serum testosterone, EROD and GST were sensitive endpoints to PCP. PCP may have endocrine disrupting activities and may affect the reproductive success of this species. It is possible that the changes of hepatic microsome enzyme activities may result in alterations of serum testosterone levels in crucian carp.

  17. Foetal life protein provision of mink (Neovison vison) changes the relative mRNA abundance of some hepatic enzymes regulating fat metabolism.

    PubMed

    Matthiesen, Connie Frank; Casañas, Maria Arantzazu Aguinaga; Tauson, Anne-Helene

    2014-01-01

    The nutrient provision to pregnant females has high impact on the growth and metabolism of their offspring. The objective was to investigate if the expression of hepatic enzymes regulating the fat metabolism was affected in foetuses and adult female mink born by dams fed either a low or an adequate level of protein during late gestation. The relative abundances of acetyl coenzyme A carboxylase (ACC), fatty acid synthase (FAS) and carnitine palmitoyl transferase 1 (CPT1) mRNA were determined by qualitative polymerase chain reaction in the livers of F₀- and F₁-generation dams and in F₁-generation foetuses. Low protein provision during foetal life resulted in a lower expression of FAS in foetal liver but a tendency towards increased expression in the liver of adult dams. There was a tendency towards an effect of life stage of the animal on the expression of ACC resulting in a higher expression among F₁ foetuses exposed to low protein during foetal life than F₀ dams fed a low protein diet during late gestation. The expression of CPT1 was significantly lower among dams exposed to low protein provision during foetal life than controls, possibly indicating a lower rate of mitochondrial β-oxidation. Further investigations are needed to clarify the consequences of these changes for the fat metabolism.

  18. Detection of antibodies to hepatitis C virus (HCV) structural proteins in anti-HCV-positive sera by an enzyme-linked immunosorbent assay using synthetic peptides as antigens.

    PubMed Central

    Ishida, C; Matsumoto, K; Fukada, K; Matsushita, K; Shiraki, H; Maeda, Y

    1993-01-01

    We have defined 10 linear immunogenic regions encoded by the putative hepatitis C virus (HCV) structural proteins (core and envelope) by employing an enzyme-linked immunosorbent assay (ELISA) and by using 17 sequential synthetic peptides covering the N-terminal 330 amino acids of the structural polyproteins as antigens. These peptides correspond to amino acids 1 to 24, 21 to 44, 42 to 68, 64 to 91, and 100 to 120 of the putative core protein and amino acids 192 to 212, 223 to 238, 236 to 258, 250 to 266, and 307 to 330 of the putative envelope protein. In particular, the peptide covering amino acids 21 to 44 of the core protein was reactive with all but one (40 of 41) of the serum samples giving a positive signal in the passive hemagglutination assay (PHA) using the core and nonstructural proteins (NS 3/4) of the virus as antigens. We detected the HCV genome in 25 (61%) of 41 PHA-positive serum samples by the polymerase chain reaction (PCR) test. Of 25 PCR-positive serum samples, 17 serum samples had reactivity to the peptides derived from the envelope protein. On the other hand, only 1 of the 16 PCR-negative serum samples had reactivity to the peptides derived from the envelope protein. Interestingly, we often observed high serum alanine aminotransferase levels in PCR-positive individuals bearing antibodies to the envelope protein. PMID:7681849

  19. Induction of drug metabolism in man after rifampicin treatment measured by increased hexobarbital and tolbutamide clearance.

    PubMed

    Zilly, W; Breimer, D D; Richter, E

    1975-12-19

    Five healthy volunteers took 1.2 g rifampicin daily for 8 days, and before and afterwards each received hexobarbital (7.32 mg/kg) and tolbutamide (20 mg/kg) by i.v. infusion on two consecutive days. The plasma concentrations of the two drugs were determined during and after infusion. The average elimination half-life of hexobarbital had decreased from 325 to 122 min and of tolbutamide from 418 to 183 min following rifampicin treatment. It was calculated that the metabolic clearance of hexobarbital had increased about three-fold and that of tolbutamide more than two-fold. Significant changes in the distribution kinetics of the two drugs were not observed. The results suggest that rifampicin is capable of inducing drug metabolism in man, which leads to an increased rate of elimination of drugs that undergo biotransformation in the liver.

  20. Molecular Networking As a Drug Discovery, Drug Metabolism, and Precision Medicine Strategy.

    PubMed

    Quinn, Robert A; Nothias, Louis-Felix; Vining, Oliver; Meehan, Michael; Esquenazi, Eduardo; Dorrestein, Pieter C

    2017-02-01

    Molecular networking is a tandem mass spectrometry (MS/MS) data organizational approach that has been recently introduced in the drug discovery, metabolomics, and medical fields. The chemistry of molecules dictates how they will be fragmented by MS/MS in the gas phase and, therefore, two related molecules are likely to display similar fragment ion spectra. Molecular networking organizes the MS/MS data as a relational spectral network thereby mapping the chemistry that was detected in an MS/MS-based metabolomics experiment. Although the wider utility of molecular networking is just beginning to be recognized, in this review we highlight the principles behind molecular networking and its use for the discovery of therapeutic leads, monitoring drug metabolism, clinical diagnostics, and emerging applications in precision medicine.

  1. Diminution of Hepatic Response to 7, 12-dimethylbenz(α)anthracene by Ethyl Acetate Fraction of Acacia catechu Willd. through Modulation of Xenobiotic and Anti-Oxidative Enzymes in Rats

    PubMed Central

    Kumar, Rakesh; Kaur, Rajbir; Singh, Amrit Pal; Arora, Saroj

    2014-01-01

    Background Liver is the primary metabolizing site of body and is prone to damage by exogenous as well as endogenous intoxicants. Polycyclic aromatic hydrocarbons such as 7, 12- dimethylbenz(α)anthracene (DMBA) is an exogenous hepatotoxin, which is well known for modulating phase I, II and anti-oxidative enzymes of liver. Plants contain plethora of polyphenolic compounds which can reverse the damaging effect of various xenobiotics. The present study investigated protective role of the ethyl acetate fraction of Acacia catechu Willd. (EAF) against DMBA induced alteration in hepatic metabolizing and anti-oxidative enzymes in rats. Methodology and Principal Findings The rats were subjected to hepatic damage by treating with DMBA for 7 weeks on alternative days and treatment schedule was terminated at the end of 14 weeks. The rats were euthanized at the end of protocol and livers were homogenized. The liver homogenates were used to analyse phase I (NADPH-cytochrome P450 reducatse, NADH-cytochrome b5 reductase, cytochrome P420, cytochrome b5), phase II (glutathione-S-transferase, DT diaphorase and γ-Glutamyl transpeptidase) and antioxidative enzymes (catalase, superoxide dismutase, ascorbate peroxidase, glutathione reductase, guiacol peroxidase and lactate dehydrogenase). Furthermore, other oxidative stress parameters (thiobarbituric acid reactive substances, lipid hydroperoxides and conjugated dienes and reduced glutathione) and liver marker enzymes (serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase and alkaline phosphatase) were also studied. The DMBA induced significant changes in activity of hepatic enzymes that was reversed by treatment with three dose levels of EAF. Conclusion It is concluded that EAF affords hepato-protection against DMBA in rats through modulation of phase I, II and anti-oxidative enzymes. PMID:24587216

  2. Modulation of cytochrome P450 enzymes in response to continuous or intermittent high-fat diet in pigs.

    PubMed

    Puccinelli, Emanuela; Gervasi, Pier Giovanni; Pelosi, Gualtiero; Puntoni, Mariarita; Longo, Vincenzo

    2013-08-01

    1. To date, no information has been available on the modulation of cytochrome P450 enzymes (CYPs) following the administration of a hyperlipidemic diet in pigs. 2. We investigated the potential modulation of xenobiotic-metabolizing CYPs in liver, heart and duodenum of pigs subjected to a high-fat/high-cholesterol diet for 2 months continuously (C-HFD) or on alternate weeks (A-HFD). 3. The administration of the high-fat diet resulted in considerably increased plasma cholesterol levels although the animals were still able to manage the lipid overload efficiently, and no sign of effective tissue inflammation occurred in livers. Plasma lipid profile and liver histology indicated a better adaptive response of the A-HFD pigs compared to the C-HFD group. We showed a post-transcriptional induction of hepatic CYP2E1 activity in C-HFD pigs and a transcriptional induction of hepatic CYP3As - especially in the A-HFD group. No further CYP modulation was observed in either liver or extra-hepatic tissues. 4. In conclusion, the administration of a high-fat diet in pigs resulted in limited effects on the drug metabolism system. The better adaptive response of A-HFD pigs compared to C-HFD pigs is a very interesting observation since the intermittent administration of the diet reflects the mode of human behavior more closely.

  3. Application of a Newly Developed High-Sensitivity HBsAg Chemiluminescent Enzyme Immunoassay for Hepatitis B Patients with HBsAg Seroclearance

    PubMed Central

    Shinkai, Noboru; Matsuura, Kentaro; Sugauchi, Fuminaka; Watanabe, Tsunamasa; Murakami, Shuko; Iio, Etsuko; Ogawa, Shintaro; Nojiri, Shunsuke; Joh, Takashi

    2013-01-01

    We modified and automated a highly sensitive chemiluminescent enzyme immunoassay (CLEIA) for surface antigen (HBsAg) detection using a combination of monoclonal antibodies, each for a specific epitope of HBsAg, and by improving an earlier conjugation technique. Of 471 hepatitis B virus (HBV) carriers seen in our hospital between 2009 and 2012, 26 were HBsAg seronegative as determined by the Abbott Architect assay. The Lumipulse HBsAg-HQ assay was used to recheck those 26 patients who demonstrated seroclearance by the Abbott Architect assay. The performance of the Lumipulse HBsAg-HQ assay was compared with that of a quantitative HBsAg detection system (Abbott Architect) and the Roche Cobas TaqMan HBV DNA assay (CTM) (lower limit of detection, 2.1 log copies/ml) using blood serum samples from patients who were determined to be HBsAg seronegative by the Abbott Architect assay. Ten patients had spontaneous HBsAg loss. Of 8 patients treated with nucleotide analogues (NAs), two were HBsAg seronegative after stopping lamivudine therapy and 6 were HBsAg seronegative during entecavir therapy. Eight acute hepatitis B (AH) patients became HBsAg seronegative. Of the 26 patients, 16 were HBsAg positive by the Lumipulse HBsAg-HQ assay but negative by the Abbott Architect assay. The differences between the two assays in terms of detectable HBsAg persisted over the long term in the spontaneous loss group (median, 10 months), the NA-treated group (2.5 months), and the AH group (0.5 months). In 9 patients, the Lumipulse HBsAg-HQ assay detected HBsAg when HBV DNA was negative by the CTM assay. HBsAg was also detected by the Lumipulse HBsAg-HQ assay in 4 patients with an anti-HBs concentration of >10 mIU/ml, 3 of whom had no HBsAg escape mutations. The automatic, highly sensitive HBsAg CLEIA Lumipulse HBsAg-HQ is a convenient and precise assay for HBV monitoring. PMID:23946517

  4. Generation and characterization of a transgenic mouse model with hepatic expression of human CYP2A6.

    PubMed

    Zhang, Qing-Yu; Gu, Jun; Su, Ting; Cui, Huadong; Zhang, Xiuling; D'Agostino, Jaime; Zhuo, Xiaoliang; Yang, Weizhu; Swiatek, Pamela J; Ding, Xinxin

    2005-12-09

    The aim of this study was to prepare and characterize a transgenic mouse model in which CYP2A6, a human P450 enzyme, is expressed specifically in the liver. CYP2A6, which is mainly expressed in human liver, is active toward many xenobiotics. Our transgene construct contained the mouse transthyretin promoter/enhancer, a full-length CYP2A6 cDNA, and a downstream neomycin-resistance gene for positive selection in embryonic stem cells. Hepatic expression of the CYP2A6 transgene was demonstrated by immunoblotting, whereas tissue specificity of CYP2A6 expression was confirmed by RNA-PCR. The transgenic mouse was further characterized after being backcrossed to the B6 strain for six generations. Hepatic microsomes from homozygous transgenic mice had activities significantly higher than those of B6 mice toward coumarin. The in vivo activity of transgenic CYP2A6 was also determined. Systemic clearance of coumarin was significantly higher in the transgenic mice than in B6 controls, consistent with the predicted role of CYP2A6 as the major coumarin hydroxylase in human liver. The CYP2A6-transgenic mouse model should be valuable for studying the in vivo function of this polymorphic human enzyme in drug metabolism and chemical toxicity.

  5. Hepatitis A

    MedlinePlus

    Hepatitis A Hepatitis A Hepatitis A is a contagious viral infection that can easily affect children and adults. It is one of the most common types of hepatitis virus. Often when you hear about hepatitis A ...

  6. Polymorphisms in drug-metabolizing enzymes and steady-state exemestane concentration in post-menopausal patients with breast cancer

    PubMed Central

    Hertz, Daniel L.; Kidwell, Kelley M.; Seewald, Nicholas J.; Gersch, Christina L.; Desta, Zeruesenay; Flockhart, David A; Storniolo, Ana-Maria; Stearns, Vered; Skaar, Todd C; Hayes, Daniel F; Henry, N. Lynn; Rae, James M.

    2016-01-01

    Discovery of clinical and genetic predictors of exemestane pharmacokinetics was attempted in 246 post-menopausal patients with breast cancer enrolled on a prospective clinical study. A sample was collected two hours after exemestane dosing at a 1 or 3 month study visit to measure drug concentration. The primary hypothesis was that patients carrying the low-activity CYP3A4*22 (rs35599367) SNP would have greater exemestane concentration. Additional SNPs in genes relevant to exemestane metabolism (CYP1A1/2, CYP1B1, CYP3A4, CYP4A11, AKR1C3/4, AKR7A2) were screened in secondary analyses and adjusted for clinical covariates. CYP3A4*22 was associated with a 54% increase in exemestane concentration (p<0.01). Concentration was greater in patients who reported White race, had elevated aminotransferases, renal insufficiency, lower body mass index, and had not received chemotherapy (all p<0.05), and CYP3A4*22 maintained significance after adjustment for covariates (p<0.01). These genetic and clinical predictors of exemestane concentration may be useful for treatment individualization in patients with breast cancer. PMID:27549341

  7. 2D SMARTCyp Reactivity-Based Site of Metabolism Prediction for Major Drug-Metabolizing Cytochrome P450 Enzymes

    DTIC Science & Technology

    2012-05-25

    ranked 1 , 2, and 3 positions in 67%, 80%, and 83% of the cases, respectively. The results were similar to those obtained by MetaSite and the reactivity...docking approach. For 70 CYP2C9 substrates, the observed sites of CYP2C9 metabolism were among the top-ranked 1 , 2, and 3 positions in 66%, 86%, and...respectively. For 36 compounds metabolized by CYP2C19, the observed sites of metabolism were found to be among the top-ranked 1 , 2, and 3 sites in 78%, 89

  8. Regulation of hepatic energy metabolism by the nuclear receptor PXR.

    PubMed

    Hakkola, Jukka; Rysä, Jaana; Hukkanen, Janne

    2016-09-01

    The pregnane X receptor (PXR) is a nuclear receptor that is traditionally thought to be specialized for sensing xenobiotic exposure. In concurrence with this feature PXR was originally identified to regulate drug-metabolizing enzymes and transporters. During the last ten years it has become clear that PXR harbors broader functions. Evidence obtained both in experimental animals and humans indicate that ligand-activated PXR regulates hepatic glucose and lipid metabolism and affects whole body metabolic homeostasis. Currently, the consequences of PXR activation on overall metabolic health are not yet fully understood and varying results on the effect of PXR activation or knockout on metabolic disorders and weight gain have been published in mouse models. Rifampicin and St. John's wort, the prototypical human PXR agonists, impair glucose tolerance in healthy volunteers. Chronic exposure to PXR agonists could potentially represent a risk factor for diabetes and metabolic syndrome. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie.

  9. Hepatic microsomal cytochrome P450 enzyme activity in relation to in vitro metabolism/inhibition of polychlorinated biphenyls and testosterone in Baltic grey seal (Halichoerus grypus).

    PubMed

    Li, Hongxia; Boon, Jan P; Lewis, Wilma E; van den Berg, Martin; Nyman, Madeleine; Letcher, Robert J

    2003-03-01

    Among other factors, cytochrome P450 (CYP) enzyme activity determines polychlorinated biphenyl (PCB) bioaccumulation, biotransformation, and toxicity in exposed species. We measured the oxidative metabolism in vitro of 12 PCB congeners, representing structural groups based on the number and position of the chlorine atoms, by the hepatic microsomes of one Baltic grey seal (Halichoerus grypus). Microsomal metabolism was observed for several PCBs with vicinal H atoms exclusively in the ortho and meta positions and without any ortho-Cl substituents (CB-15 [4,4'-Cl2] and CB-77 [3,3',4,4'-Cl4]), vicinal meta and para-H atoms (CB-52 [2,2',5,5'-Cl4], and -101 [2,2',4,5,5'-Cl5]) or with both characteristics in combination with either only one ortho-Cl (CB-26 [2,3',5-Cl3], CB-31 [2,4',5-Cl3]) or two ortho-Cl substituents (CB-44 [2,2',3,5'-Cl4]). To allocate PCB biotransformation to specific CYPs, the inhibitive effect of compounds with known CYP-specific inhibition properties was assessed on in vitro PCB metabolism and on regio- and stereospecific testosterone hydroxylase activities. Metabolic inhibition was considered relevant at concentrations < or = 1.0 microM because these inhibitors became decreasingly selective at higher concentrations. At < 1.0 microM, ellipticine (CYPIAI/2 inhibitor) selectively inhibited CB-15, -26, -31, and -77 metabolism, with no significant inhibition of CB-44, -52, and -101 metabolism. Inhibition of CB-52 and -101 metabolism by chloramphenicol (CYP2B inhibitor) started at 1.0 microM and maximized at about 100% at 10 microM. Ketoconazole (CYP3A inhibitor) appeared to selectively inhibit CB-26, -31, and -44 metabolism relative to CB-15, -77, and -52 at concentrations < or = 1.0 microM. Major testosterone metabolites formed in vitro were 2beta-(CYP3A), 6beta- (CYP3A, CYPIA), and 16beta- (CYP2B) hydroxytestosterone and androstenedione (CYP2B, CYP2C11). The CYP forms indicated are associated with the specific metabolism of testosterone in laboratory

  10. Influence of rifampicin on drug metabolism: differences between hexobarbital and antipyrine.

    PubMed

    Breimer, D D; Zilly, W; Richter, E

    1977-04-01

    Six healthy volunteers were treated with 1,200 mg of rifampicin daily for 8 days. Before and immediately afterward each received indocyanine green, hexobarbital, galactose, and antipyrine by intravenous infusion on 3 consecutive days. The plasma concentrations of the drugs were determined several times after infusion. The average elimination half-life of hexobarbital had decreased from 407 to 171 min and its metabolic clearance had increased almost threefold. In contrast, the average elimination half-life of antipyrine was virtually the same on both occasions (6.9 and 7.2 hr) and there was no change in metabolic clearance. In a tuberculous patient treated with rifampicin the antipyrine elimination rate was unaffected. Rifampicin did not influence indocyanine green clearance or galactose elimination capacity. Serum gamma glutamyl transferase was not affected but urinary D-glucaric acid excretion was increased during rifampicin treatment. The experiment with hexobarbital was repeated after 2 weeks in all subjects; half-lives and clearance values had returned to near control values. It appears that rifampicin is a selective inducer of oxidative drug metabolism in man.

  11. Drug metabolism and liver disease: a drug-gene-environment interaction.

    PubMed

    Zgheib, Nathalie K; Branch, Robert A

    2017-02-01

    Despite the central role of the liver in drug metabolism, surprisingly there is lack of certainty in anticipating the extent of modification of the clearance of a given drug in a given patient. The intent of this review is to provide a conceptual framework in considering the impact of liver disease on drug disposition and reciprocally the impact of drug disposition on liver disease. It is proposed that improved understanding of the situation is gained by considering the issue as a special example of a drug-gene-environment interaction. This requires an integration of knowledge of the drug's properties, knowledge of the gene products involved in its metabolism, and knowledge of the pathophysiology of its disposition. This will enhance the level of predictability of drug disposition and toxicity for a drug of interest in an individual patient. It is our contention that advances in pharmacology, pharmacogenomics, and hepatology, together with concerted interests in the academic, regulatory, and pharmaceutical industry communities provide an ideal immediate environment to move from a qualitative reactive approach to quantitative proactive approach in individualizing patient therapy in liver disease.

  12. Drug Metabolism and Pharmacokinetics, the Blood-Brain Barrier, and Central Nervous System Drug Discovery

    PubMed Central

    Alavijeh, Mohammad S.; Chishty, Mansoor; Qaiser, M. Zeeshan; Palmer, Alan M.

    2005-01-01

    Summary: The worldwide market for therapies for CNS disorders is worth more than $50 billion and is set to grow substantially in the years ahead. This is because: 1) the incidence of many CNS disorders (e.g., Alzheimer’s disease, stroke, and Parkinson’s disease) increase exponentially after age 65 and 2) the number of people in the world over 65 is about to increase sharply because of a marked rise in fertility after World War II. However, CNS research and development are associated with significant challenges: it takes longer to get a CNS drug to market (12–16 years) compared with a non-CNS drug (10–12 years) and there is a higher attrition rate for CNS drug candidates than for non-CNS drug candidates. This is attributable to a variety of factors, including the complexity of the brain, the liability of CNS drugs to cause CNS side effects, and the requirement of CNS drugs to cross the blood-brain barrier (BBB). This review focuses on BBB penetration, along with pharmacokinetics and drug metabolism, in the process of the discovery and development of safe and effective medicines for CNS disorders. PMID:16489365

  13. Cryopreservation of precision-cut tissue slices for application in drug metabolism research.

    PubMed

    de Graaf, I A M; Koster, H J

    2003-02-01

    Cryopreservation of tissue slices greatly facilitates their use in drug metabolism research, leading to efficient use of human organ material and a decrease of laboratory animal use. In the present review, various mechanisms of cryopreservation such as equilibrium slow freezing, rapid freezing and vitrification, and their application to cryopreservation of tissue slices are discussed as well as the viability parameters often used to evaluate the success of cryopreservation. Equilibrium freezing prevents intracellular ice formation by inducing cellular dehydration, but (large) ice crystals are still formed in the interstitial space of the slices. Upon rapid freezing, (small) intra- and extracellular ice crystals are formed which slices from some tissues can resist. Vitrification prevents the formation of both intra- and extracellular ice crystals while an amorphous glass is formed of the slice liquid constituents. To vitrify, however, high molarity solutions of cryoprotectants are required that may be toxic to the slices. The use of mixtures of high molarity of cryoprotectants overcomes this problem. We conclude that vitrification is the approach that most likely will lead to the development of universal cryopreservation methods for tissue slices of various organs from various animal species. In the future this may lead to the formation of a tissue slice bank from which slices can be derived at any desirable time point for in vitro experimentation.

  14. Effects of Nonalcoholic Fatty Liver Disease on Hepatic CYP2B1 and in Vivo Bupropion Disposition in Rats Fed a High-Fat or Methionine/Choline-Deficient Diet.

    PubMed

    Cho, Sung-Joon; Kim, Sang-Bum; Cho, Hyun-Jong; Chong, Saeho; Chung, Suk-Jae; Kang, Il-Mo; Lee, Jangik Ike; Yoon, In-Soo; Kim, Dae-Duk

    2016-07-13

    Nonalcoholic fatty liver disease (NAFLD) refers to hepatic pathologies, including simple fatty liver (SFL), nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis, that may progress to hepatocellular carcinoma. These liver disease states may affect the activity and expression levels of drug-metabolizing enzymes, potentially resulting in an alteration in the pharmacokinetics, therapeutic efficacy, and safety of drugs. This study investigated the hepatic cytochrome P450 (CYP) 2B1-modulating effect of a specific NAFLD state in dietary rat models. Sprague-Dawley rats were given a methionine/choline-deficient (MCD) or high-fat (HF) diet to induce NASH and SFL, respectively. The induction of these disease states was confirmed by plasma chemistry and liver histological analysis. Both the protein and mRNA levels of hepatic CYP2B1 were considerably reduced in MCD diet-fed rats; however, they were similar between the HF diet-fed and control rats. Consistently, the enzyme-kinetic and pharmacokinetic parameters for CYP2B1-mediated bupropion metabolism were considerably reduced in MCD diet-fed rats; however, they were also similar between the HF diet-fed and control rats. These results may promote a better understanding of the influence of NAFLD on CYP2B1-mediated metabolism, which could have important implications for the safety and pharmacokinetics of drug substrates for the CYP2B subfamily in patients with NAFLD.

  15. Hepatitis C

    MedlinePlus

    ... Châu và vùng Thái Bình Dương Hepatitis C Hepatitis C What is hepatitis C? Hepatitis C is a viral infection that ... can cure most cases of hepatitis C. Acute hepatitis C Acute hepatitis C is a short-term ...

  16. Hepatitis A

    MedlinePlus

    ... Châu và vùng Thái Bình Dương Hepatitis C Hepatitis A What is hepatitis A? Hepatitis A is a viral infection that ... spreading hepatitis A to others . How common is hepatitis A? In the United States, hepatitis A has ...

  17. Hepatitis B

    MedlinePlus

    ... Châu và vùng Thái Bình Dương Hepatitis C Hepatitis B What is hepatitis B? Hepatitis B is a viral infection that ... to prevent spreading hepatitis B to others . Acute hepatitis B Acute hepatitis B is a short-term ...

  18. Mutagenic activation and detoxification of benzo[a]pyrene in vitro by hepatic cytochrome P450 1A1 and phase II enzymes in three meat-producing animals.

    PubMed

    Darwish, W; Ikenaka, Y; Eldaly, E; Ishizuka, M

    2010-01-01

    The mutagenic activation activity of hepatic microsomes from three meat-producing animals (cattle, deer and horses) was compared with those of rats as a reference species. In the Ames Salmonella typhimurium TA98 assay, the liver microsomes of all examined animals mutagenically activated benzo[a]pyrene, an ideal promutagens, in terms of production of histidine-independent revertant colonies. The microsomes of horses had the highest ability to produce revertant colonies of the examined animals under both low and high substrate concentrations. Inhibition of this mutagenic activity using alpha-naphthoflavone, anti-rat CYP1A1, CYP3A2 and CYP2E1 antibodies suggests that this activity was mainly because of CYP1A1 in these animals as well as in rats. The addition of co-factors for two phase II enzymes, microsomal UDP glucoronosyl transferase and cytosolic glutathione-S-transferase, reduced the production of the revertant colonies in a concentration-dependent manner. Interestingly, horses had the highest reduction rate among the examined animals, suggesting that phase II enzymes play a great role in producing a state of balance between the bioactivation and detoxification of xenobiotics in these meat-producing animals. This report is the first to investigate the mutagenic activation activity of the hepatic microsomes and the role of phase II enzymes against this activity in meat-producing animals.

  19. Propiconazole increases reactive oxygen species levels in mouse hepatic cells in culture and in mouse liver by a cytochrome P450 enzyme mediated process

    EPA Science Inventory

    Propiconazole induces hepatocarcinomas and hepatoadenomas in mice and is a rat liver tumor promoter. Transcriptional, proteomic, metabolomic and biochemical studies of hepatic tissues from mice treated with propiconazole under the conditions of the chronic bioassay indicate that ...

  20. SENESCENCE-ASSOCIATED DECLINE IN HEPATIC PEROXISOMAL ENZYME ACTIVITIES CORRESPONDS WITH DIMINISHED LEVELS OF RETINOID X RECEPTOR ALPHA, BUT NOT PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR ALPHA1

    EPA Science Inventory

    Abstract

    Aging is associated with alterations in hepatic peroxisomal metabolism and susceptibility to hepatocarcinogenecity produced by agonists of peroxisome proliferator-activated receptor alpha (PPARa). Mechanisms involved in these effects are not well understood. Howev...

  1. Cinnamaldehyde/chemotherapeutic agents interaction and drug-metabolizing genes in colorectal cancer.

    PubMed

    Yu, Chen; Liu, Shen-Lin; Qi, Ming-Hao; Zou, Xi

    2014-02-01

    Cinnamaldehyde is an active monomer isolated from the stem bark of Cinnamomum cassia, a traditional oriental medicinal herb, which is known to possess marked antitumor effects in vitro and in vivo. The aim of the present study was to examine the potential advantages of using cinnamaldehyde in combination with chemotherapeutic agents commonly used in colorectal carcinoma (CRC) therapy, as well as to investigate the effect of cinnamaldehyde on chemotherapeutic-associated gene expression. The synergistic interaction of cinnamaldehyde and chemotherapeutic agents on human CRC HT-29 and LoVo cells was evaluated using the combination index (CI) method. The double staining with Annexin V conjugated to fluorescein-isothiocyanate and phosphatidylserine was employed for apoptosis detection. The expression of drug-metabolizing genes, including excision repair cross‑complementing 1 (ERCC1), orotate phosphoribosyltransferase (OPRT), thymidylate synthase (TS), breast cancer susceptibility gene 1 (BRCA1) and topoisomerase 1 (TOPO1), all in HT-29 and LoVo cells, with or without the addition of cinnamaldehyde, was examined by quantitative polymerase chain reaction (PCR). Cinnamaldehyde had a synergistic effect on the chemotherapeutic agents cytotoxicity in HT-29 and LoVo cells. In addition, cinnamaldehyde suppressed BRCA1, TOPO1, ERCC1 and TS mRNA expression, except for OPRT expression, which was markedly upregulated. Our findings indicate that cinnamaldehyde appears to be a promising candidate as an adjuvant in combination therapy with 5-fluorouracil (5-FU) and oxaliplatin (OXA), two chemotherapeutic agents used in CRC treatment. The possible mechanisms of its action may involve the regulation of drug‑metabolizing genes.

  2. Viral Hepatitis

    MedlinePlus

    ... Public Home » For Veterans and the Public Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... the Public Veterans and Public Home How is Hepatitis C Treated? Find the facts about the newest ...

  3. Autoimmune Hepatitis

    MedlinePlus

    ... Cholangitis Wilson Disease Liver Disease A-Z Autoimmune Hepatitis What is autoimmune hepatitis? Autoimmune hepatitis is a chronic—or long lasting— ... bacteria, viruses, toxins, and medications. What causes autoimmune hepatitis? A combination of autoimmunity, environmental triggers, and a ...

  4. Viral Hepatitis

    MedlinePlus

    ... with hepatitis? How does a pregnant woman pass hepatitis B virus to her baby? If I have hepatitis B, what does my baby need so that she ... Can I breastfeed my baby if I have hepatitis B? More information on viral hepatitis What is hepatitis? ...

  5. A pregnancy physiologically based pharmacokinetic (p-PBPK) model for disposition of drugs metabolized by CYP1A2, CYP2D6 and CYP3A4

    PubMed Central

    Gaohua, Lu; Abduljalil, Khaled; Jamei, Masoud; Johnson, Trevor N; Rostami-Hodjegan, Amin

    2012-01-01

    Aims Pregnant women are usually not part of the traditional drug development programme. Pregnancy is associated with major biological and physiological changes that alter the pharmacokinetics (PK) of drugs. Prediction of the changes to drug exposure in this group of patients may help to prevent under- or overtreatment. We have used a pregnancy physiologically based pharmacokinetic (p-PBPK) model to assess the likely impact of pregnancy on three model compounds, namely caffeine, metoprolol and midazolam, based on the knowledge of their disposition in nonpregnant women and information from in vitro studies. Methods A perfusion-limited form of a 13-compartment full-PBPK model (Simcyp® Simulator) was used for the nonpregnant women, and this was extended to the pregnant state by applying known changes to all model components (including the gestational related activity of specific cytochrome P450 enzymes) and through the addition of an extra compartment to represent the fetoplacental unit. The uterus and the mammary glands were grouped into the muscle compartment. The model was implemented in Matlab Simulink and validated using clinical observations. Results The p-PBPK model predicted the PK changes of three model compounds (namely caffeine, metoprolol and midazolam) for CYP1A2, CYP2D6 and CYP3A4 during pregnancy within twofold of observed values. The changes during the third trimester were predicted to be a 100% increase, a 30% decrease and a 35% decrease in the exposure of caffeine, metoprolol and midazolam, respectively, compared with the nonpregnant women. Conclusions In the absence of clinical data, the in silico prediction of PK behaviour during pregnancy can provide a valuable aid to dose adjustment in pregnant women. The performance of the model for drugs metabolized by a single enzyme to different degrees (high and low extraction) and for drugs that are eliminated by several different routes warrants further study. PMID:22725721

  6. Modeling chronic hepatitis B or C virus infection during antiviral therapy using an analogy to enzyme kinetics: long-term viral dynamics without rebound and oscillation.

    PubMed

    Takayanagi, Toshiaki

    2013-12-01

    The basic model for chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection during therapy enables us to analyze short-term viral kinetics. However, the model is not useful for analyzing long-term viral kinetics. Here, I suggest a new model that was obtained by introducing Michaelis-Menten kinetics into the basic model. The new model can exhibit long-term viral kinetics without rebound and oscillation, unlike the basic model. The value of the parameter K in the new model is analogous to the Michaelis constant Km and is predicted to be approximately less than 10(10)/ml.

  7. Evaluation of hepatic metabolism and pharmacokinetics of ibuprofen in rats under chronic hypobaric hypoxia for targeted therapy at high altitude.

    PubMed

    Gola, Shefali; Gupta, Asheesh; Keshri, Gaurav K; Nath, Madhu; Velpandian, Thirumurthy

    2016-03-20

    With studies indicative of altered drug metabolism and pharmacokinetics (DMPK) under high altitude (HA)-induced hypobaric hypoxia, consideration of better therapeutic approaches has continuously been aimed in research for HA related illness management. DMPK of drugs like ibuprofen may get affected under hypoxia which establishes the requirement of different therapeutic dose regimen to ensure safe and effective therapy at HA. This study examined the effects of the chronic hypobaric hypoxia (CHH) on hepatic DMPK of ibuprofen in rats. Experimental animals were exposed to simulated altitude of 7620 m (∼25,000 ft) for CHH exposure (7 or 14 days) in decompression chamber and administered with ibuprofen (80 mg/kg, body weight, p.o.). Results demonstrated that CHH significantly altered PK variables of ibuprofen and activities of both phase-I and II hepatic metabolic enzymes as compared to the animals under normoxic conditions. Hepatic histopathological observations also revealed marked alterations. Increase in pro-inflammatory cytokines/chemokines viz. IL-1β, IL-2, IFN-γ, TNF-α exhibited close relevance with diminished CYP2C9 expression under CHH. Moreover, the down-regulated CYP2C9 level further supported the underlying mechanism for reduced metabolism of ibuprofen and as a result, increased retention of parent drug in the system. Increased mean retention time, Vd, T½ of ibuprofen, and decreased AUC, Cmax and clearance during CHH further strengthened the present findings. In conclusion, CHH exposure significantly affects hepatic DMPK of ibuprofen, which may further influence the usual therapeutic dose-regimen. Further, there is requirement of human studies to evaluate their susceptibility toward hypobaric hypoxia.

  8. Inhibition of cytochrome P450 enzymes by saturated and unsaturated fatty acids in human liver microsomes, characterization of enzyme kinetics in the presence of bovine serum albumin (0.1 and 1.0% w/v) and in vitro - in vivo extrapolation of hepatic clearance.

    PubMed

    Palacharla, Raghava Choudary; Uthukam, Venkatesham; Manoharan, Arunkumar; Ponnamaneni, Ranjith Kumar; Padala, Nagasurya Prakash; Boggavarapu, Rajesh Kumar; Bhyrapuneni, Gopinadh; Ajjala, Devender Reddy; Nirogi, Ramakrishna

    2017-04-01

    The objective of the study was to determine the effect of fatty acids on CYP enzymes and the effect of BSA on intrinsic clearance of probe substrates. The inhibitory effect of thirteen fatty acids including saturated, mono-unsaturated and polyunsaturated fatty acids on CYP enzymes, kinetic parameters and intrinsic clearance values of nine CYP marker probe substrate reactions in the absence and presence of BSA (0.1 and 1.0% w/v) were characterized in human liver microsomes. The results demonstrate that most of the unsaturated fatty acids showed marked inhibition towards CYP2C8 mediated amodiaquine N-deethylation followed by inhibition of CYP2C9 and CYP2B6 mediated activities. The addition of 0.1% BSA in the incubation markedly improved the unbound intrinsic clearance values of probe substrates by reducing the Km values with little or no effect on maximal velocity. The addition of BSA (0.1 and 1.0% w/v) did not influence the unbound intrinsic clearance of marker reactions for CYP2A6, and CYP3A4 enzymes. The addition of 0.1% w/v BSA is sufficient to determine the intrinsic clearance of marker probe reactions by metabolite formation approach. The predicted hepatic clearance values for the substrates using the well-stirred model, in the presence of BSA (0.1% BSA), are comparable to the in vivo hepatic clearance values.

  9. Tissue-specific contaminant accumulation and associated effects on hepatic serum analytes and cytochrome P450 enzyme activities in hooded seals (Cystophora cristata) from the Gulf of St. Lawrence.

    PubMed

    Wolkers, Hans; Boily, France; Fink-Gremmels, Johanna; van Bavel, Bert; Hammill, Mike O; Primicerio, Raul

    2009-02-01

    The current study aims to assess contaminant levels and tissue burdens in hooded seal (Cystophora cristata) blubber, liver, and blood in association with cytochrome P450 (CYP) enzymes (CYP1A and -3A) and serum analytes (hepatic enzymes like alanine aminotransferase [ALT], aspartate aminotransferase, alkaline phosphatase [AP], and gamma-glutamyltransferase [GGT], serum proteins, and creatine kinase). Contaminant accumulation levels and patterns of polychlorinated biphenyls, chlorinated pesticides, and polybrominated diphenyl ethers (PBDEs) differed between tissues and seal groups, with the highest levels in liver. Pups showed higher liver contaminant levels, especially for PBDEs, than adults. These high levels might be associated with the ingestion of large amounts of contaminated milk and subsequent accumulation in the liver. Adult males and females mainly differed in PBDE levels, which were higher in females, possibly due to a sex-specific diet. The association between blubber contaminant burdens and the diagnostic enzymes ALT, GGT, and AP, and serum albumin, was inconclusive. In contrast, several CYP isoenzymes showed a clear positive relationship with the overall blubber contaminant burden, indicating enzyme induction following exposure to polyhalogenated hydrocarbons. Therefore, liver CYP isoenzymes may serve as a sensitive biomarker for long-term exposure to polyhalogenated hydrocarbons.

  10. [Interaction between CYP450 enzymes and metabolism of traditional Chinese medicine as well as enzyme activity assay].

    PubMed

    Lu, Tu-lin; Su, Lian-lin; Ji, De; Gu, Wei; Mao, Chun-qin

    2015-09-01

    Drugs are exogenous compounds for human bodies, and will be metabolized by many enzymes after administration. CYP450 enzyme, as a major metabolic enzyme, is an important phase I drug metabolizing enzyme. In human bodies, about 75% of drug metabolism is conducted by CYP450 enzymes, and CYP450 enzymes is the key factor for drug interactions between traditional Chinese medicine( TCM) -TCM, TCM-medicine and other drug combination. In order to make clear the interaction between metabolic enzymes and TCM metabolism, we generally chose the enzymatic activity as an evaluation index. That is to say, the enhancement or reduction of CYP450 enzyme activity was used to infer the inducing or inhibitory effect of active ingredients and extracts of traditional Chinese medicine on enzymes. At present, the common method for measuring metabolic enzyme activity is Cocktail probe drugs, and it is the key to select the suitable probe substrates. This is of great significance for study drug's absorption, distribution, metabolism and excretion (ADME) process in organisms. The study focuses on the interaction between TCMs, active ingredients, herbal extracts, cocktail probe substrates as well as CYP450 enzymes, in order to guide future studies.

  11. Alterations in enzymes in an Indian catfish, Clarias batrachus (Linn.), exposed to vanadium

    SciTech Connect

    Chakraborty, A.; Bhattacharjee, S.; Chatterjee, M.

    1995-02-01

    The increase in air and water borne concentrations of vanadium, a physiologically and pharmacologically active substance, has caused renewed interest in the toxicology of this metal. Toxicity studies of vanadium on fish are comparatively scarce. Cytochrome P-450 monoxygenases and conjugating enzymes are important in fish metabolism and elimination of endogenous as well as foreign lipophilic compounds. These enzymes are also known to participate in activation and inactivation of carcinogenic and environmental chemicals. (In vitro) investigations have shown that fish metabolize xenobiotics by mechanisms very similar to those found in mammals. Impairment of drug-metabolizing enzymes is thus deleterious to the organism. Heavy metals are known to influence this group of enzymes. This prompted us to investigate the effect of vanadate, in a dose-responsive and time-dependent manner, on the relative rates and patterns of hepatic glutathione transferase (GST) activity, UDP-glucuronyl transferase (UDPGT) activity and cytochrome P-450 (Cyt P-450) level in an Indian catfish, Clarias batrachus. We chose an aquatic species for our experiment since the environment where aquatic animals live is the main destination of industrial and agricultural wastes. The variations recorded in the level and activity of cytochrome P-450, glutathione transferase and UDP-glu-curonyl transferase are discussed in relation to carcinogenic risk depending on the environment of the fish. In support of the above, petroleum has been found to induce cytochrome P-450 and subsequently produce high levels of neoplasia in fish. Furthermore, GST, UDPGT and Cyt P-450 have been reported as reliable markers for preneoplastic lesions in liver. 21 refs., 3 tabs.

  12. Biofabrication of a three-dimensional liver micro-organ as an in vitro drug metabolism model.

    PubMed

    Chang, Robert; Emami, Kamal; Wu, Honglu; Sun, Wei

    2010-12-01

    In their normal in vivo matrix milieu, tissues assume complex well-organized three-dimensional architectures. Therefore, the primary aim in the tissue engineering design process is to fabricate an optimal analog of the in vivo scenario. This challenge can be addressed by applying emerging layered biofabrication approaches in which the precise configuration and composition of cells and bioactive matrix components can recapitulate the well-defined three-dimensional biomimetic microenvironments that promote cell-cell and cell-matrix interactions. Furthermore, the advent of and refinements in microfabricated systems can present physical and chemical cues to cells in a controllable and reproducible fashion unmatched with conventional cultures, resulting in the precise construction of engineered biomimetic microenvironments on the cellular length scale in geometries that are readily parallelized for high throughput in vitro models. As such, the convergence of layered solid freeform fabrication (SFF) technologies along with microfabrication techniques enables the creation of a three-dimensional micro-organ device to serve as an in vitro platform for cell culture, drug screening or to elicit further biological insights, particularly for NASA's interest in a flight-suitable high-fidelity microscale platform to study drug metabolism in space and planetary environments. The proposed model in this paper involves the combinatorial setup of an automated syringe-based, layered direct cell writing bioprinting process with micro-patterning techniques to fabricate a microscale in vitro device housing a chamber of bioprinted three-dimensional liver cell-encapsulated hydrogel-based tissue constructs in defined design patterns that biomimic the cell's natural microenvironment for enhanced biological functionality. In order to assess the structural formability and biological feasibility of such a micro-organ, reproducibly fabricated tissue constructs were biologically characterized for

  13. Hepatitis C

    MedlinePlus

    ... your doctor may want you to get the hepatitis B vaccine (and maybe the hepatitis A vaccine, too), if you don't already have these viruses. If you have hepatitis C, you are more likely to catch hepatitis A or hepatitis B, which would cause more damage to your liver. ...

  14. Evaluating the Role of Drug Metabolism and Reactive Intermediates in Trazodone-Induced Cytotoxicity toward Freshly-Isolated Rat Hepatocytes.

    PubMed

    Najibi, A; Heidari, R; Zarifi, J; Jamshidzadeh, A; Firoozabadi, N; Niknahad, H

    2016-11-01

    Background: Trazodone is an antidepressant agent widely administered for the treatment of depressive disorders. On the other hand, several cases of hepatic injury have been reported after Trazodone administration. Although the precise mechanism(s) of trazodone-induced liver injury is not known, some investigations proposed the role of reactive intermediates in this complication. This study was designed to investigate the role of reactive metabolites in hepatocytes injury induced by trazodone. Methods: Isolated rat hepatocytes were prepared by the method of collagenase enzyme perfusion via the portal vein. Cells were treated with trazodone, its cytotoxic metabolite, and different enzyme inhibitors and cytoprotective agents. Results: It was found that trazodone was toxic towards hepatocytes and caused 50% cell death after 2 h of incubation at a dose of 450 µM. The trazodone postulated reactive metabolite; m-chlorophenyl piperazine (m-CPP) was less toxic and caused 50% cell death at a dose of 750 µM at a similar time period. Cellular glutathione (GSH) depletion and lipid peroxidation were detected when hepatocytes were treated with trazodone and/or m-CPP. Depleting hepatocytes GSH beforehand, increased cytotoxicity of both trazodone and m-CPP. Troleandomycin as the CYP3A4 inhibitor prevented cytotoxicity of trazodone but slightly affected m-CPP-induced cell injury. Inhibition of CYP2D6 by quinidine and cimetidine increased the cytotoxicity of both trazodone and m-CPP. Antioxidants and ATP suppliers slightly prevented cytotoxicity of trazodone and m-CPP. Conclusion: As inhibitors of CYP3A4 and 2D6 affected trazodone cytotoxicity, it is suggested that trazodone -induced cytotoxicity, at least in part, is mediated by its reactive metabolites.

  15. Long-term exposure to abnormal glucose levels alters drug metabolism pathways and insulin sensitivity in primary human hepatocytes

    PubMed Central

    Davidson, Matthew D.; Ballinger, Kimberly R.; Khetani, Salman R.

    2016-01-01

    Hyperglycemia in type 2 diabetes mellitus has been linked to non-alcoholic fatty liver disease, which can progress to inflammation, fibrosis/cirrhosis, and hepatocellular carcinoma. Understanding how chronic hyperglycemia affects primary human hepatocytes (PHHs) can facilitate the development of therapeutics for these diseases. Conversely, elucidating the effects of hypoglycemia on PHHs may provide insights into how the liver adapts to fasting, adverse diabetes drug reactions, and cancer. In contrast to declining PHH monocultures, micropatterned co-cultures (MPCCs) of PHHs and 3T3-J2 murine embryonic fibroblasts maintain insulin-sensitive glucose metabolism for several weeks. Here, we exposed MPCCs to hypo-, normo- and hyperglycemic culture media for ~3 weeks. While albumin and urea secretion were not affected by glucose level, hypoglycemic MPCCs upregulated CYP3A4 enzyme activity as compared to other glycemic states. In contrast, hyperglycemic MPCCs displayed significant hepatic lipid accumulation in the presence of insulin, while also showing decreased sensitivity to insulin-mediated inhibition of glucose output relative to a normoglycemic control. In conclusion, we show for the first time that PHHs exposed to hypo- and hyperglycemia can remain highly functional, but display increased CYP3A4 activity and selective insulin resistance, respectively. In the future, MPCCs under glycemic states can aid in novel drug discovery and mechanistic investigations. PMID:27312339

  16. Long-term exposure to abnormal glucose levels alters drug metabolism pathways and insulin sensitivity in primary human hepatocytes

    NASA Astrophysics Data System (ADS)

    Davidson, Matthew D.; Ballinger, Kimberly R.; Khetani, Salman R.

    2016-06-01

    Hyperglycemia in type 2 diabetes mellitus has been linked to non-alcoholic fatty liver disease, which can progress to inflammation, fibrosis/cirrhosis, and hepatocellular carcinoma. Understanding how chronic hyperglycemia affects primary human hepatocytes (PHHs) can facilitate the development of therapeutics for these diseases. Conversely, elucidating the effects of hypoglycemia on PHHs may provide insights into how the liver adapts to fasting, adverse diabetes drug reactions, and cancer. In contrast to declining PHH monocultures, micropatterned co-cultures (MPCCs) of PHHs and 3T3-J2 murine embryonic fibroblasts maintain insulin-sensitive glucose metabolism for several weeks. Here, we exposed MPCCs to hypo-, normo- and hyperglycemic culture media for ~3 weeks. While albumin and urea secretion were not affected by glucose level, hypoglycemic MPCCs upregulated CYP3A4 enzyme activity as compared to other glycemic states. In contrast, hyperglycemic MPCCs displayed significant hepatic lipid accumulation in the presence of insulin, while also showing decreased sensitivity to insulin-mediated inhibition of glucose output relative to a normoglycemic control. In conclusion, we show for the first time that PHHs exposed to hypo- and hyperglycemia can remain highly functional, but display increased CYP3A4 activity and selective insulin resistance, respectively. In the future, MPCCs under glycemic states can aid in novel drug discovery and mechanistic investigations.

  17. Activation of CAR and PXR by Dietary, Environmental and Occupational Chemicals Alters Drug Metabolism, Intermediary Metabolism, and Cell Proliferation

    PubMed Central

    Hernandez, J.P.; Mota, L.C.; Baldwin, W.S.

    2010-01-01

    The constitutive androstane receptor (CAR) and the pregnane × receptor (PXR) are activated by a variety of endogenous and exogenous ligands, such as steroid hormones, bile acids, pharmaceuticals, and environmental, dietary, and occupational chemicals. In turn, they induce phase I–III detoxification enzymes and transporters that help eliminate these chemicals. Because many of the chemicals that activate CAR and PXR are environmentally-relevant (dietary and anthropogenic), studies need to address whether these chemicals or mixtures of these chemicals may increase the susceptibility to adverse drug interactions. In addition, CAR and PXR are involved in hepatic proliferation, intermediary metabolism, and protection from cholestasis. Therefore, activation of CAR and PXR may have a wide variety of implications for personalized medicine through physiological effects on metabolism and cell proliferation; some beneficial and others adverse. Identifying the chemicals that activate these promiscuous nuclear receptors and understanding how these chemicals may act in concert will help us predict adverse drug reactions (ADRs), predict cholestasis and steatosis, and regulate intermediary metabolism. This review summarizes the available data on CAR and PXR, including the environmental chemicals that activate these receptors, the genes they control, and the physiological processes that are perturbed or depend on CAR and PXR action. This knowledge contributes to a foundation that will be necessary to discern interindividual differences in the downstream biological pathways regulated by these key nuclear receptors. PMID:20871735

  18. Association of the Nonalcoholic Hepatic Steatosis and Its Degrees With the Values of Liver Enzymes and Homeostasis Model Assessment-Insulin Resistance Index

    PubMed Central

    Cruz, Mario Augusto Ferreira; Cruz, Josilda Ferreira; Macena, Larissa Baracho; de Santana, Demetrius Silva; Oliveira, Cristiane Costa da Cunha; Lima, Sonia Oliveira; Franca, Alex Vianey Callado

    2015-01-01

    Background Nonalcoholic fatty liver disease (NAFLD) is among the most common chronic diseases of the modern world with a wide variety of factors including genetic, environmental and metabolic. The aim of this study was to verify the association between the degrees of hepatic steatosis at the abdominal ultrasound and the values of aminotransferases (aspartate aminotransferase (AST) and alanine transferase (ALT)), gamma glutamyl transpeptidase (GGT) and homeostasis model assessment-insulin resistance (HOMA-IR) index. Methods A prospective, descriptive survey study, using a quantitative analytical examination, was conducted from July 2013 to July 2014. In the statistical analysis, values were expressed as median, first and third quartiles. We used the nonparametric Kruskal-Wallis test to compare the medians between the degrees of steatosis, adopted a statistical significance of 5% (P ≤ 0.05) and used the statistical program SPSS 22.0. Results We diagnosed 233/800 (29.1%) patients with hepatic steatosis on routine ultrasound, and 65.7% were female. Regarding degrees, 119 had grade 1 (51.0%), 94 grade 2 (40.4%) and 20 grade 3 (8.6%). The median age of the patients with grade 1, 2 or 3 did not vary significantly (P > 0.05). The median body mass index (BMI), although clinically important because of its elevation, did not differ significantly (P > 0.05). ALT levels increased as the degree of hepatic steatosis has advanced as well as the levels of AST, GGT and HOMA-IR. AST values showed a greater association with the severity of fatty liver (P = 0.0001) than the ALT (P = 0.001). Conclusions ALT, AST, GGT and HOMA-IR are associated to the degrees of hepatic steatosis on ultrasound and can help in the selection of patients for the liver histological evaluation. PMID:27785306

  19. Quantum Mechanics/Molecular Mechanics Modeling of Drug Metabolism: Mexiletine N-Hydroxylation by Cytochrome P450 1A2.

    PubMed

    Lonsdale, Richard; Fort, Rachel M; Rydberg, Patrik; Harvey, Jeremy N; Mulholland, Adrian J

    2016-06-20

    The mechanism of cytochrome P450(CYP)-catalyzed hydroxylation of primary amines is currently unclear and is relevant to drug metabolism; previous small model calculations have suggested two possible mechanisms: direct N-oxidation and H-abstraction/rebound. We have modeled the N-hydroxylation of (R)-mexiletine in CYP1A2 with hybrid quantum mechanics/molecular mechanics (QM/MM) methods, providing a more detailed and realistic model. Multiple reaction barriers have been calculated at the QM(B3LYP-D)/MM(CHARMM27) level for the direct N-oxidation and H-abstraction/rebound mechanisms. Our calculated barriers indicate that the direct N-oxidation mechanism is preferred and proceeds via the doublet spin state of Compound I. Molecular dynamics simulations indicate that the presence of an ordered water molecule in the active site assists in the binding of mexiletine in the active site, but this is not a prerequisite for reaction via either mechanism. Several active site residues play a role in the binding of mexiletine in the active site, including Thr124 and Phe226. This work reveals key details of the N-hydroxylation of mexiletine and further demonstrates that mechanistic studies using QM/MM methods are useful for understanding drug metabolism.

  20. Rational prescription of drugs within similar therapeutic or structural class for gastrointestinal disease treatment: Drug metabolism and its related interactions

    PubMed Central

    Zhou, Quan; Yan, Xiao-Feng; Zhang, Zhong-Miao; Pan, Wen-Sheng; Zeng, Su

    2007-01-01

    AIM: To review and summarize drug metabolism and its related interactions in prescribing drugs within the similar therapeutic or structural class for gastrointestinal disease treatment so as to promote rational use of medicines in clinical practice. METHODS: Relevant literature was identified by performing MEDLINE/Pubmed searches covering the period from 1988 to 2006. RESULTS: Seven classes of drugs were chosen, including gastric proton pump inhibitors, histamine H2-receptor antagonists, benzamide-type gastroprokinetic agents, selective 5-HT3 receptor antagonists, fluoroquinolones, macrolide antibiotics and azole antifungals. They showed significant differences in metabolic profile (i.e., the fraction of drug metabolized by cytochrome P450 (CYP), CYP reaction phenotype, impact of CYP genotype on interindividual pharmacokinetics variability and CYP-mediated drug-drug interaction potential). Many events of severe adverse drug reactions and treatment failures were closely related to the ignorance of the above issues. CONCLUSION: Clinicians should acquaint themselves with what kind of drug has less interpatient variability in clearance and whether to perform CYP genotyping prior to initiation of therapy. The relevant CYP knowledge helps clinicians to enhance the management of patients with gastrointestinal disease who may require treatment with polytherapeutic regimens. PMID:17948937

  1. Development of an On-animal Separation-based Sensor for Monitoring Drug Metabolism in Freely Roaming Sheep

    PubMed Central

    Scott, David E.; Willis, Sean D.; Gabbert, Seth; Johnson, Dave A.; Naylor, Erik; Janle, Elsa M.; Krichevsky, Janice E.; Lunte, Craig E.; Lunte, Susan M.

    2015-01-01

    The development of an on-animal separation-based sensor that can be employed for monitoring drug metabolism in a freely roaming sheep is described. The system consists of microdialysis sampling coupled directly to microchip electrophoresis with electrochemical detection (MD-ME-EC). Separations were accomplished using an all-glass chip with integrated platinum working and reference electrodes. Discrete samples from the microdialysis flow were introduced into the electrophoresis chip using a flow-gated injection approach. Electrochemical detection was accomplished in-channel using a two-electrode isolated potentiostat. Nitrite was separated by microchip electrophoresis using reverse polarity and a run buffer consisting of 50 mM phosphate at pH 7.4. The entire system was under telemetry control. The system was first tested with rats to monitor the production of nitrite following introduction of nitroglycerin into the subdermal tissue using a linear probe. The data acquired using the on-line MD-ME-EC system was compared to that obtained off-line analysis by liquid chromatography with electrochemical detection (LC-EC), using a second microdialysis probe implanted parallel to the first probe in the same animal. The MD-ME-EC device was then used on-animal to monitor the subdermal metabolism of nitroglycerin in sheep. The ultimate goal is to use this device to simultaneously monitor drug metabolism and behavior in a freely roaming animal. PMID:25697221

  2. Hepatitis C

    MedlinePlus

    Hepatitis C Overview By Mayo Clinic Staff Hepatitis C is a viral infection that causes liver inflammation, sometimes leading to serious liver damage. The hepatitis C virus (HCV) spreads through contaminated ...

  3. Toxic Hepatitis

    MedlinePlus

    Toxic hepatitis Overview By Mayo Clinic Staff Toxic hepatitis is an inflammation of your liver in reaction to certain substances to which you're exposed. Toxic hepatitis can be caused by alcohol, chemicals, drugs or ...

  4. Coordinating Role of RXRα in Downregulating Hepatic Detoxification during Inflammation Revealed by Fuzzy-Logic Modeling.

    PubMed

    Keller, Roland; Klein, Marcus; Thomas, Maria; Dräger, Andreas; Metzger, Ute; Templin, Markus F; Joos, Thomas O; Thasler, Wolfgang E; Zell, Andreas; Zanger, Ulrich M

    2016-01-01

    During various inflammatory processes circulating cytokines including IL-6, IL-1β, and TNFα elicit a broad and clinically relevant impairment of hepatic detoxification that is based on the simultaneous downregulation of many drug metabolizing enzymes and transporter genes. To address the question whether a common mechanism is involved we treated human primary hepatocytes with IL-6, the major mediator of the acute phase response in liver, and characterized acute phase and detoxification responses in quantitative gene expression and (phospho-)proteomics data sets. Selective inhibitors were used to disentangle the roles of JAK/STAT, MAPK, and PI3K signaling pathways. A prior knowledge-based fuzzy logic model comprising signal transduction and gene regulation was established and trained with perturbation-derived gene expression data from five hepatocyte donors. Our model suggests a greater role of MAPK/PI3K compared to JAK/STAT with the orphan nuclear receptor RXRα playing a central role in mediating transcriptional downregulation. Validation experiments revealed a striking similarity of RXRα gene silencing versus IL-6 induced negative gene regulation (rs = 0.79; P<0.0001). These results concur with RXRα functioning as obligatory heterodimerization partner for several nuclear receptors that regulate drug and lipid metabolism.

  5. Coordinating Role of RXRα in Downregulating Hepatic Detoxification during Inflammation Revealed by Fuzzy-Logic Modeling

    PubMed Central

    Thomas, Maria; Dräger, Andreas; Metzger, Ute; Templin, Markus F.; Joos, Thomas O.; Thasler, Wolfgang E.; Zell, Andreas; Zanger, Ulrich M.

    2016-01-01

    During various inflammatory processes circulating cytokines including IL-6, IL-1β, and TNFα elicit a broad and clinically relevant impairment of hepatic detoxification that is based on the simultaneous downregulation of many drug metabolizing enzymes and transporter genes. To address the question whether a common mechanism is involved we treated human primary hepatocytes with IL-6, the major mediator of the acute phase response in liver, and characterized acute phase and detoxification responses in quantitative gene expression and (phospho-)proteomics data sets. Selective inhibitors were used to disentangle the roles of JAK/STAT, MAPK, and PI3K signaling pathways. A prior knowledge-based fuzzy logic model comprising signal transduction and gene regulation was established and trained with perturbation-derived gene expression data from five hepatocyte donors. Our model suggests a greater role of MAPK/PI3K compared to JAK/STAT with the orphan nuclear receptor RXRα playing a central role in mediating transcriptional downregulation. Validation experiments revealed a striking similarity of RXRα gene silencing versus IL-6 induced negative gene regulation (rs = 0.79; P<0.0001). These results concur with RXRα functioning as obligatory heterodimerization partner for several nuclear receptors that regulate drug and lipid metabolism. PMID:26727233

  6. Human Liver Mitochondrial Cytochrome P450 2D6: Individual Variations and Implications in Drug Metabolism

    PubMed Central

    Cook Sangar, Michelle L.; Anandatheerthavarada, Hindupur K.; Tang, Weigang; Prabu, Subbuswamy K.; Martin, Martha V.; Dostalek, Miroslav; Guengerich, F. Peter; Avadhani, Narayan G.

    2009-01-01

    Summary Constitutively expressed human cytochrome P450 2D6 (CYP2D6) is responsible for the metabolism of approximately 25% of drugs in common clinical use. It is widely accepted that CYP2D6 is localized in the endoplasmic reticulum of cells; however, we have identified this enzyme in the mitochondria of human liver samples and found that extensive inter-individual variability exists in the level of the mitochondrial enzyme. Metabolic assays using 7-methoxy-4-aminomethylcoumarin as a substrate show that the human liver mitochondrial enzyme is capable of oxidizing this substrate and that the catalytic activity is supported by mitochondrial electron transfer proteins. Here we show that CYP2D6 contains an N-terminal chimeric signal that mediates its bimodal targeting to the endoplasmic reticulum (ER) and mitochondria. In vitro mitochondrial import studies using both N-terminal deletions and point mutations suggest that the mitochondrial targeting signal is localized between residues 23-33 and that the positively charged residues at positions 24, 25, 26, 28, and 32 are required for mitochondrial targeting. The importance of the positively charged residues was confirmed by transient transfection of a CYP2D6 mitochondrial targeting signal mutant in COS-7 cells. Both the mitochondria and the microsomes from a CYP2D6 stable expression cell line contain the enzyme and both fractions exhibit bufuralol 1′-hydroxylation activity, which is completely inhibited by CYP2D6 inhibitory antibody. Overall these results suggest that the targeting of CYP2D6 to mitochondria could be an important physiological process that has significance in xenobiotic metabolism. PMID:19438707

  7. Changes in hepatic lipogenic and oxidative enzymes and glucose homeostasis induced by an acetyl-L-carnitine and nicotinamide treatment in dyslipidaemic insulin-resistant rats.

    PubMed

    Ferreira, Maria R; Camberos, Maria del C; Selenscig, Dante; Martucci, Lucía C; Chicco, Adriana; Lombardo, Yolanda B; Cresto, Juan C

    2013-03-01

    Normal rats fed a sucrose-rich diet (SRD) develop dyslipidaemia and insulin resistance. The present study examined whether administration of the mitochondrial nutrients nicotinamide and acetyl-L-carnitine reversed or improved these metabolic abnormalities. Male Wistar rats were fed an SRD for 90 days. Half the rats then received daily injections of nicotinamide (25 mg/kg, i.p.) and acetyl-L-carnitine (50 mg/kg, i.p.) for a further 90 days. The remaining rats in the SRD-fed group and those in a normal chow-fed control group were injected with an equal volume of saline solution for the same period. The following parameters were determined in all groups: (i) liver activity of fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC) and carnitine-palmitoyl transferase-1 (CPT-1); (ii) hepatic and skeletal muscle triacylglycerol content, plasma glucose, insulin, free fatty acid (FFA) and triacylglycerol levels and pancreatic insulin content; and (iii) glucose tolerance. Administration of nicotinamide and acetyl-L-carnitine to the SRD-fed rats reduced dyslipidaemia, liver steatosis, muscle triacylglycerol content and hepatic FAS and ACC activities and increased CPT-1 activity. In addition nicotinamide and acetyl-L-carnitine improved the glucose disappearance rate (K(g)), normalized plasma glucose levels and moderately increased insulinaemia without altering pancreatic insulin content. Finally, nicotinamide and acetyl-l-carnitine administration reduced bodyweight gain and visceral adiposity. The results of the present study suggest that altering key hepatic lipogenic and fatty acid oxidative enzymatic activity could improve dyslipidaemia, liver steatosis and visceral adiposity. Indeed, administration of nicotinamide and acetyl-l-carnitine improved glucose intolerance and normalized plasma glucose levels.

  8. Role of hepatitis B virus X repression of C/EBPbeta activity in the down-regulation of glutathione S-transferase A2 gene: implications in other phase II detoxifying enzyme expression.

    PubMed

    Cho, I J; Ki, S H; Brooks, C; Kim, S G

    2009-02-01

    1. A genome-wide in silico screening rendered the genes of phase II enzymes in the rat genome whose promoters contain the putative DNA elements interacting with CCAAT/enhancer binding protein (C/EBP) and NF-E2-related factor (Nrf2). The hepatitis B virus X (HBx) protein strongly modulates the transactivation and/or the repression of genes regulated by some bZIP transcription factors. 2. This study investigated the effects of HBx on the induction of phase II enzymes with the aim of elucidating the role of HBx interaction with C/EBPbeta or Nrf2 bZIP transcription factors in hepatocyte-derived cells. 3. Immunoblot and reporter gene analyses revealed that transfection of HBx interfered with the constitutive and inducible GSTA2 transactivation promoted by oltipraz (C/EBPbeta activator), but not that by tert-butylhydroquinone (t-BHQ, Nrf2 activator). Moreover, HBx transfection completely inhibited GSTA2 reporter gene activity induced by C/EBPbeta, but failed to inhibit that by Nrf2. 4. Gel shift assays identified that HBx inhibited the increase in C/EBPbeta-DNA complex formation by oltipraz, but not the increase in Nrf2-DNA complex by t-BHQ. Immunoprecipitation and immunoblot assays verified the direct interaction between HBx and C/EBPbeta. Moreover, chromatin immunoprecipitation assays confirmed HBx inhibition of C/EBPbeta binding to its binding site in the GSTA2 gene promoter. HBx repressed the induction of other phase II enzymes including GSTP, UDP-glucuronyltransferase 1A, microsomal epoxide hydrolase, GSTM1, GSTM2, and gamma-glutamylcysteine synthase. 5. These results demonstrate that HBx inhibits the induction of phase II detoxifying enzymes, which is mediated by its interaction with C/EBPbeta, but not Nrf2, substantiating the specific role of HBx in phase II detoxifying capacity.

  9. Protective Effect of Free and Bound Polyphenol Extracts from Ginger (Zingiber officinale Roscoe) on the Hepatic Antioxidant and Some Carbohydrate Metabolizing Enzymes of Streptozotocin-Induced Diabetic Rats.

    PubMed

    Kazeem, Mutiu Idowu; Akanji, Musbau Adewunmi; Yakubu, Musa Toyin; Ashafa, Anofi Omotayo Tom

    2013-01-01

    This study investigated the hepatoprotective effects of polyphenols from Zingiber officinale on streptozotocin-induced diabetic rats by assessing liver antioxidant enzymes, carbohydrate-metabolizing enzymes and liver function indices. Initial oral glucose tolerance test was conducted using 125 mg/kg, 250 mg/kg, and 500 mg/kg body weight of both free and bound polyphenols from Z. officinale. 28 day daily oral administration of 500 mg/kg body weight of free and bound polyphenols from Z. officinale to streptozotocin-induced (50 mg/kg) diabetic rats significantly reduced (P < 0.05) the fasting blood glucose compared to control groups. There was significant increase (P < 0.05) in the antioxidant enzymes activities in the animals treated with both polyphenols. Similarly, the polyphenols normalised the activities of some carbohydrate metabolic enzymes (hexokinase and phosphofructokinase) in the liver of the rats treated with it and significantly reduced (P < 0.05) the activities of liver function enzymes. The results from the present study have shown that both free and bound polyphenols from Z. officinale especially the free polyphenol could ameliorate liver disorders caused by diabetes mellitus in rats. This further validates the use of this species as medicinal herb and spice by the larger population of Nigerians.

  10. Serum serotonin reduced the expression of hepatic transporter Mrp2 and P-gp via regulating nuclear receptor CAR in PI-IBS rats.

    PubMed

    Shao, Yun-Yun; Huang, Jing; Ma, Yan-Rong; Han, Miao; Ma, Kang; Qin, Hong-Yan; Rao, Zhi; Wu, Xin-An

    2015-08-01

    Hepatic transporters and drug metabolizing enzymes (DMEs) play important roles in the pharmacological effects and (or) side-effects of many drugs, and are regulated by several mediators, including neurotransmitters. This work aimed to investigate whether serum levels of 5-hydroxytryptamine (5-HT) affected the expression of hepatic transporters or DMEs. The expression of hepatic transporters was assessed using the Western-blot technique in a 2,4,6-trinitrobenzenesulfonic-acid-induced rat model of post-infectious irritable bowel syndrome (PI-IBS), in which serum levels of 5-HT were significantly elevated. To further clarify the underlying mechanism, the 5-HT precursor 5-hydroxytryptophan (5-HTP) and the 5-HT depleting agent parachlorophenylalanine (pCPA) were applied to adjust serum levels of 5-HT. Serum levels of 5-HT were measured using LC-MS/MS; the expression of hepatic transporters, DMEs, and nuclear receptors were examined by Western-blot technique. Our results showed that in PI-IBS rats the expression of multidrug resistance protein 2 (Mrp2) was significantly decreased, while colonic enterochromaffin cell density and serum levels of 5-HT were all significantly increased. Moreover, 5-HTP treatment significantly increased serum levels of 5-HT and decreased the expression of Mrp2 and glycoprotein P (P-gp), whereas treatment with pCPA markedly decreased serum levels of 5-HT and increased the expression of Mrp2 and P-gp. Our results indicated that serum 5-HT regulates the expression of Mrp2 and P-gp, and the underlying mechanism may be related to the altered expression of the nuclear receptor constitutive androstane receptor (CAR).

  11. The quantitative prediction of in vivo enzyme-induction caused by drug exposure from in vitro information on human hepatocytes.

    PubMed

    Kato, Motohiro; Chiba, Koji; Horikawa, Masato; Sugiyama, Yuichi

    2005-08-01

    There have been no reports of the quantitative prediction of induction for drug-metabolizing enzymes in humans. We have tried to predict such enzyme induction in humans from in vitro data obtained using human hepatocytes. The in vitro and in vivo data on enzyme induction by inducers, such as rifampicin, phenobarbital and omeprazole, were collected from the published literature. The degree of enzyme induction in humans was compared with that predicted from in vitro data on human hepatocytes. Using the in vivo data, we calculated the hepatic intrinsic clearance of typical CYP substrates, such as midazolam and caffeine, before and after inducer treatment and estimated the induction ratios of hepatic intrinsic clearance following treatment. In the in vitro studies, the amount of mRNA or enzyme and enzyme activity in human hepatocytes, with or without an inducer, were compared and the induction ratios were estimated. The unbound mean concentration was taken as an index of drug exposure and the induction ratios in the in vivo and in vitro studies were compared. The unbound mean concentrations of inducers used in the in vitro studies were higher than those in the in vivo studies. The maximum induction ratios by inducers in the in vitro studies were higher than those in the in vivo studies. The induction ratio for rifampicin, omeprazole, troglitazone, dexamethasone and phenobarbital increased as the unbound mean concentration increased to reach a constant value. The induction of CYP3A and 1A was analyzed by the Emax model. The maximum induction ratio (Emax) and the concentration at half maximum induction (EC50) for rifampicin, omeprazole, troglitazone, dexamethasone and phenobarbital were 12.3, 0.847 micromol/L, 2.36, 0.225 micromol/L, 6.86, 0.002 micromol/L, 8.30, 9.32 micromol/L, and 7.62, 58.4 micromol/L, respectively. The Emax and EC50 of omeprazole for CYP1A were 12.02 and 0.075 micromol/L, respectively. The predicted induction ratio of all those inducers, except for

  12. Hepatitis B and HIV

    MedlinePlus

    ... Problems : Hepatitis B Subscribe Translate Text Size Print Hepatitis B What is Hepatitis? Hepatitis means inflammation of the liver. This condition ... our related pages, Hepatitis A and Hepatitis C . Hepatitis B and HIV About 10% of people living ...

  13. [Studies on drug metabolism in obese men and mice (author's transl)].

    PubMed

    Grimmel, K; Richter, E; Zilly, W

    1979-03-01

    In 7 obese patients with an overweight of 53 +/- 19% of Broca we found a 2-fold enlarged apparent volume of distribution and a nearly 2-fold prolonged elimination halflife of hexobarbital; the hexobarbital plasma clearance however, which is nearly identical with the metabolizing capacity of the liver for hexobarbital, was not decreased. Phenobarbital induced the microsomal drugmetabolizing enzyme system in the fatty liver of genetically obese mice in the same way 2-3-fold as in the non-fatty liver of the lean littermates.

  14. The Aldo-Keto Reductase Superfamily and its Role in Drug Metabolism and Detoxification

    PubMed Central

    Barski, Oleg A.; Tipparaju, Srinivas M.; Bhatnagar, Aruni

    2008-01-01

    The Aldo-Keto Reductase (AKR) superfamily comprises of several enzymes that catalyze redox transformations involved in biosynthesis, intermediary metabolism and detoxification. Substrates of the family include glucose, steroids, glycosylation end products, lipid peroxidation products, and environmental pollutants. These proteins adopt a (β/α)8 barrel structural motif interrupted by a number of extraneous loops and helixes that vary between proteins and bring structural identity to individual families. The human AKR family differs from the rodent families. Due to their broad substrate specificity, AKRs play an important role in the Phase II detoxification of a large number of pharmaceuticals, drugs, and xenobiotics. PMID:18949601

  15. Equine hepatocytes: isolation, cryopreservation, and applications to in vitro drug metabolism studies.

    PubMed

    Shibany, Khaled A; Tötemeyer, Sabine; Pratt, Stefanie L; Paine, Stuart W

    2016-10-01

    Despite reports of the successful isolation of primary equine hepatocytes, there are no published data regarding the successful cryopreservation of these isolated cells. In this study, a detailed description of the procedures for isolation, cryopreservation, and recovery of equine hepatocytes are presented. Furthermore, the intrinsic clearance (Clint) and production of metabolites for three drugs were compared between freshly isolated and recovered cryopreserved hepatocytes. Primary equine hepatocytes were isolated using a two-step collagenase perfusion method, with an average cell yield of 2.47 ± 2.62 × 10(6) cells/g of perfused liver tissue and viability of 84.1 ± 2.62%. These cells were cryopreserved with William's medium E containing 10% fetal bovine serum with 10% DMSO. The viability of recovered cells, after a 30% Percoll gradient, was 77 ± 11% and estimated recovery rate was approximately 27%. These purified cells were used to determine the in vitro Clint of three drugs used in equine medicine; omeprazole, flunixin, and phenylbutazone, via the substrate depletion method. Cryopreserved suspensions gave a comparable estimation of Clint compared to fresh cells for these three drugs as well as producing the same metabolites. This work paves the way for establishing a bank of cryopreserved equine hepatocytes that can be used for estimating pharmacokinetic parameters such as the hepatic metabolic in vivo clearance of a drug as well as producing horse-specific drug metabolites.

  16. Consideration of the unbound drug concentration in enzyme kinetics.

    PubMed

    Waters, Nigel J; Obach, R Scott; Di, Li

    2014-01-01

    The study of enzyme kinetics in drug metabolism involves assessment of rates of metabolism and inhibitory potencies over a suitable concentration range. In all but the very simplest in vitro system, these drug concentrations can be influenced by a variety of nonspecific binding reservoirs that can reduce the available concentration to the enzyme system under investigation. As a consequence, the apparent kinetic parameters that are derived, such as K m or K i, can deviate from the true values. There are a number of sources of these nonspecific binding depots or barriers, including membrane permeation and partitioning, plasma or serum protein binding, and incubational binding. In the latter case, this includes binding to the assay apparatus, as well as biological depots, depending on the characteristics of the in vitro matrix being used. Given the wide array of subcellular, cellular, and recombinant enzyme systems utilized in drug metabolism, each of these has different components that can influence the free drug concentration. The physicochemical properties of the test compound are also paramount in determining the influential factors in any deviation between true and apparent kinetic behavior. This chapter describes the underlying mechanisms determining the free drug concentration in vitro and how these factors can be accounted for in drug metabolism studies, illustrated with case studies from the literature.

  17. Discovering drug–drug interactions: a text-mining and reasoning approach based on properties of drug metabolism

    PubMed Central

    Tari, Luis; Anwar, Saadat; Liang, Shanshan; Cai, James; Baral, Chitta

    2010-01-01

    Motivation: Identifying drug–drug interactions (DDIs) is a critical process in drug administration and drug development. Clinical support tools often provide comprehensive lists of DDIs, but they usually lack the supporting scientific evidences and different tools can return inconsistent results. In this article, we propose a novel approach that integrates text mining and automated reasoning to derive DDIs. Through the extraction of various facts of drug metabolism, not only the DDIs that are explicitly mentioned in text can be extracted but also the potential interactions that can be inferred by reasoning. Results: Our approach was able to find several potential DDIs that are not present in DrugBank. We manually evaluated these interactions based on their supporting evidences, and our analysis revealed that 81.3% of these interactions are determined to be correct. This suggests that our approach can uncover potential DDIs with scientific evidences explaining the mechanism of the interactions. Contact: luis.tari@roche.com PMID:20823320

  18. Identification of human hepatic cytochrome P450 enzymes involved in the metabolism of 8-prenylnaringenin and isoxanthohumol from hops (Humulus lupulus L.).

    PubMed

    Guo, Jian; Nikolic, Dejan; Chadwick, Lucas R; Pauli, Guido F; van Breemen, Richard B

    2006-07-01

    The female flowers of hops (Humulus lupulus L.) are used in the brewing of beer and are under investigation for use in dietary supplements for the management of menopausal symptoms in women. Hop extracts contain the weakly estrogenic compound isoxanthohumol (IX), proestrogenic xanthohumol, and the potent estrogen 8-prenylnaringenin (8PN). Because IX can be metabolized in the human liver to form 8PN, the specific cytochrome P450 (P450) enzymes responsible for this O-demethylation reaction were identified. In addition, the enzymes that convert IX and 8PN to their most abundant metabolites were identified because these metabolic pathways might also affect the estrogenicity of hop preparations. Specifically, the P450 enzymes that catalyze the oxidation of the prenyl side chains of IX and 8PN into trans- or cis-alcohols were investigated. Human liver microsomes and monoclonal antibodies that inhibit specific P450 enzymes were used in combination with liquid chromatography/mass spectrometry to identify the enzymes responsible for these transformations. CYP2C19 was found to catalyze the formation of both cis- and trans-alcohols of the prenyl side chain of 8PN with K(m) values of 14.8 +/- 3.2 and 16.6 +/- 4.6 microM, respectively. CYP2C8 converted 8PN regioselectively to the trans-alcohol of the prenyl group with a K(m) of 3.7 +/- 0.9 microM. Finally, CYP1A2 was found to catalyze the O-demethylation of IX to generate 8PN, with a K(m) value of 17.8 +/- 3.7 microM. These results suggest that the estrogenicity of hop constituents in vivo will depend in part on metabolic conversion that may show individual variation.

  19. Expression of Enzymes that Metabolize Medications

    NASA Technical Reports Server (NTRS)

    Wotring, Virginia E.; Peters, C. P.

    2012-01-01

    Most pharmaceuticals are metabolized by the liver. Clinically-used medication doses are given with normal liver function in mind. A drug overdose can result if the liver is damaged and removing pharmaceuticals from the circulation at a rate slower than normal. Alternatively, if liver function is elevated and removing drugs from the system more quickly than usual, it would be as if too little drug had been given for effective treatment. Because of the importance of the liver in drug metabolism we want to understand the effects of spaceflight on the enzymes of the liver.

  20. Telmisartan prevents hepatic fibrosis and enzyme-altered lesions in liver cirrhosis rat induced by a choline-deficient L-amino acid-defined diet

    SciTech Connect

    Jin Haiyan; Yamamoto, Naoki; Uchida, Koichi; Terai, Shuji; Sakaida, Isao

    2007-12-28

    Rennin-angiotensin system is involved in liver fibrogenesis through activating hepatic stellate cells (HSCs). Telmisartan (Tel) is an angiotensin II type 1 receptor antagonist, could function as a selective peroxisome proliferator-activated receptor {gamma} activator. Here we studied the effect of Tel on liver fibrosis, pre-neoplastic lesions in vivo and primary HSCs in vitro. In vivo study, we used the choline-deficient L-amino acid-defined (CDAA)-diet induced rat NASH model. The rats were fed the CDAA diet for 8 weeks to induce liver fibrosis and pre-neoplastic lesions, and then co-administrated with Tel for another 10 weeks. Tel prevented liver fibrogenesis and pre-neoplastic lesions by down-regulating TGF{beta}1 and TIMP-1, 2 and increasing MMP-13 expression. Tel inhibited HSCs activation and proliferation. These results suggested that Tel could be a promising drug for NASH related liver fibrosis.

  1. Role of Protein–Protein Interactions in Cytochrome P450-Mediated Drug Metabolism and Toxicity

    PubMed Central

    2015-01-01

    Through their unique oxidative chemistry, cytochrome P450 monooxygenases (CYPs) catalyze the elimination of most drugs and toxins from the human body. Protein–protein interactions play a critical role in this process. Historically, the study of CYP–protein interactions has focused on their electron transfer partners and allosteric mediators, cytochrome P450 reductase and cytochrome b5. However, CYPs can bind other proteins that also affect CYP function. Some examples include the progesterone receptor membrane component 1, damage resistance protein 1, human and bovine serum albumin, and intestinal fatty acid binding protein, in addition to other CYP isoforms. Furthermore, disruption of these interactions can lead to altered paths of metabolism and the production of toxic metabolites. In this review, we summarize the available evidence for CYP protein–protein interactions from the literature and offer a discussion of the potential impact of future studies aimed at characterizing noncanonical protein–protein interactions with CYP enzymes. PMID:25133307

  2. Role of protein-protein interactions in cytochrome P450-mediated drug metabolism and toxicity.

    PubMed

    Kandel, Sylvie E; Lampe, Jed N

    2014-09-15

    Through their unique oxidative chemistry, cytochrome P450 monooxygenases (CYPs) catalyze the elimination of most drugs and toxins from the human body. Protein-protein interactions play a critical role in this process. Historically, the study of CYP-protein interactions has focused on their electron transfer partners and allosteric mediators, cytochrome P450 reductase and cytochrome b5. However, CYPs can bind other proteins that also affect CYP function. Some examples include the progesterone receptor membrane component 1, damage resistance protein 1, human and bovine serum albumin, and intestinal fatty acid binding protein, in addition to other CYP isoforms. Furthermore, disruption of these interactions can lead to altered paths of metabolism and the production of toxic metabolites. In this review, we summarize the available evidence for CYP protein-protein interactions from the literature and offer a discussion of the potential impact of future studies aimed at characterizing noncanonical protein-protein interactions with CYP enzymes.

  3. Effects of 6-paradol, an unsaturated ketone from gingers, on cytochrome P450-mediated drug metabolism.

    PubMed

    Kim, Hyeong Jun; Kim, In Sook; Rehman, Shaheed Ur; Ha, Sang Keun; Nakamura, Katsunori; Yoo, Hye Hyun

    2017-02-20

    Paradols are unsaturated ketones produced by biotransformation of shogaols in gingers. Among them, 6-paradol has been investigated as a new drug candidate due to its anti-inflammatory, apoptotic, and neuroprotective activities. In this study, the inhibitory effects of 6-paradol on the activities of cytochrome P450 (CYP) enzymes were investigated with human liver microsomes and recombinant CYP isozymes. 6-Paradol showed concentration-dependent inhibitory effects on CYP1A2, CYP2B6, CYP2C8, CYP2C9, and CYP2C19 isozymes, with IC50 values ranging from 3.8 to 21.4µM in recombinant CYP isozymes. However, the inhibition was not potentiated following pre-incubation, indicating that 6-paradol is not a mechanism-based inhibitor. These results suggest that pharmacokinetic drug-drug interactions might occur with 6-paradol, which must be considered in the process of new drug development.

  4. Age-Dependent Hepatic UDP-Glucuronosyltransferase Gene Expression and Activity in Children

    PubMed Central

    Neumann, Elizabeth; Mehboob, Huma; Ramírez, Jacqueline; Mirkov, Snezana; Zhang, Min; Liu, Wanqing

    2016-01-01

    UDP-glucuronosyltransferases (UGTs) are important phase II drug metabolism enzymes. The aim of this study was to explore the relationship between age and changes in mRNA expression and activity of major human hepatic UGTs, as well as to understand the potential regulatory mechanism underlying this relationship. Using previously generated data, we investigated age-dependent mRNA expression levels of 11 hepatic UGTs (UGT1A1, UGT1A3, UGT1A4, UGT1A5, UGT1A6, UGT1A9, UGT2B4, UGT2B7, UGT2B10, UGT2B15, and UGT2B17) and 16 transcription factors (AHR, AR, CAR, ESR2, FXR, GCCR, HNF1a, HNF3a, HNF3b, HNF4a, PPARA, PPARG, PPARGC, PXR, SP1, and STAT3) in liver tissue of donors (n = 38) ranging from 0 to 25 years of age. We also examined the correlation between age and microsomal activities using 14 known UGT drug substrates in the liver samples (n = 19) of children donors. We found a statistically significant increase (nominal p < 0.05) in the expression of UGT1A1, UGT1A3, UGT1A4, UGT1A5, UGT1A6, UGT2B7, and UGT2B17, as well as glucuronidation activities of serotonin, testosterone, and vorinostat during the first 25 years of life. Expression of estrogen receptor 1 and pregnane X receptor, two strong UGT transcriptional regulators, were significantly correlated with both age and UGT mRNA expression (p ≤ 0.05). These results suggest that both UGT expression and activity increase during childhood and adolescence, possibly driven in part by hormonal signaling. Our findings may help explain inter-patient variability in response to medications among children. PMID:27899892

  5. Hepatic Transporter Expression in Metabolic Syndrome: Phenotype, Serum Metabolic Hormones, and Transcription Factor Expression.

    PubMed

    Donepudi, Ajay C; Cheng, Qiuqiong; Lu, Zhenqiang James; Cherrington, Nathan J; Slitt, Angela L

    2016-04-01

    Metabolic syndrome is a multifactorial disease associated with obesity, insulin resistance, diabetes, and the alteration of multiple metabolic hormones. Obesity rates have been rising worldwide, which increases our need to understand how this population will respond to drugs and exposure to other chemicals. The purpose of this study was to determine in lean and obese mice the ontogeny of clinical biomarkers such as serum hormone and blood glucose levels as well as the physiologic markers that correlate with nuclear receptor- and transporter-related pathways. Livers from male and female wild-type (WT) (C57BL/6) and ob/ob mice littermates were collected before, during, and after the onset of obesity. Serum hormone and mRNA levels were analyzed. Physiologic changes and gene expression during maturation and progression to obesity were performed and correlation analysis was performed using canonical correlations. Significant ontogenic changes in both WT and ob/ob mice were observed and these ontogenic changes differ in ob/ob mice with the development of obesity. In males and females, the ontogenic pattern of the expression of genes such as Abcc3, 4, Abcg2, Cyp2b10, and 4a14 started to differ from week 3, and became significant at weeks 4 and 8 in ob/ob mice compared with WT mice. In obese males, serum resistin, glucagon, and glucose levels correlated with the expression of most hepatic ATP-binding cassette (Abc) transporters, whereas in obese females, serum glucagon-like peptide 1 levels were correlated with most hepatic uptake transporters and P450 enzymes. Overall, the correlation between physiologic changes and gene expression indicate that metabolism-related hormones may play a role in regulating the genes involved in drug metabolism and transport.

  6. Metabolic Profiling of Human Long-Term Liver Models and Hepatic Clearance Predictions from In Vitro Data Using Nonlinear Mixed-Effects Modeling.

    PubMed

    Kratochwil, Nicole A; Meille, Christophe; Fowler, Stephen; Klammers, Florian; Ekiciler, Aynur; Molitor, Birgit; Simon, Sandrine; Walter, Isabelle; McGinnis, Claudia; Walther, Johanna; Leonard, Brian; Triyatni, Miriam; Javanbakht, Hassan; Funk, Christoph; Schuler, Franz; Lavé, Thierry; Parrott, Neil J

    2017-03-01

    Early prediction of human clearance is often challenging, in particular for the growing number of low-clearance compounds. Long-term in vitro models have been developed which enable sophisticated hepatic drug disposition studies and improved clearance predictions. Here, the cell line HepG2, iPSC-derived hepatocytes (iCell®), the hepatic stem cell line HepaRG™, and human hepatocyte co-cultures (HμREL™ and HepatoPac®) were compared to primary hepatocyte suspension cultures with respect to their key metabolic activities. Similar metabolic activities were found for the long-term models HepaRG™, HμREL™, and HepatoPac® and the short-term suspension cultures when averaged across all 11 enzyme markers, although differences were seen in the activities of CYP2D6 and non-CYP enzymes. For iCell® and HepG2, the metabolic activity was more than tenfold lower. The micropatterned HepatoPac® model was further evaluated with respect to clearance prediction. To assess the in vitro parameters, pharmacokinetic modeling was applied. The determination of intrinsic clearance by nonlinear mixed-effects modeling in a long-term model significantly increased the confidence in the parameter estimation and extended the sensitive range towards 3% of liver blood flow, i.e., >10-fold lower as compared to suspension cultures. For in vitro to in vivo extrapolation, the well-stirred model was used. The micropatterned model gave rise to clearance prediction in man within a twofold error for the majority of low-clearance compounds. Further research is needed to understand whether transporter activity and drug metabolism by non-CYP enzymes, such as UGTs, SULTs, AO, and FMO, is comparable to the in vivo situation in these long-term culture models.

  7. Impact of Fusarium mycotoxins on hepatic and intestinal mRNA expression of cytochrome P450 enzymes and drug transporters, and on the pharmacokinetics of oral enrofloxacin in broiler chickens.

    PubMed

    Antonissen, Gunther; Devreese, Mathias; De Baere, Siegrid; Martel, An; Van Immerseel, Filip; Croubels, Siska

    2017-03-01

    Cytochrome P450 (CYP450) drug biotransformation enzymes and multidrug resistance (MDR) proteins may influence drug disposition processes. The first part of the study aimed to evaluate the effect of mycotoxins deoxynivalenol (DON) and/or fumonisins (FBs), at contamination levels approaching European Union guidance levels, on intestinal and hepatic CYP450 enzymes and MDR proteins gene expression in broiler chickens. mRNA expression of genes encoding CYP450 enzymes (CYP3A37, CYP1A4 and CYP1A5) and drug transporters (MDR1/ABCB1 and MRP2/ABCC2) was determined using qRT-PCR. A significant up-regulation of CYP1A4 (P = 0.037) and MDR1 (P = 0.036) was observed in the jejunum of chickens fed a diet contaminated with FBs. The second part of this study aimed to investigate the impact of feeding a FBs contaminated diet on the oral absorption of enrofloxacin (10 mg/kg BW), a MDR1 substrate. A significant (P = 0.045), however small, decreased area under the plasma concentration-time curve (AUC0-48 h, mean ± SD) was observed for enrofloxacin in chickens fed the FBs contaminated diet compared to the control group, 16.28 ± 1.82 h μg/mL versus 18.27 ± 1.79 h μg/mL. These findings suggest that concurrent administration of drugs with FBs contaminated feed might alter the pharmacokinetic characteristics of CYP1A4 substrate drugs and MDR1 substrates, such as enrofloxacin.

  8. Genetic variation in genes involved in folate and drug metabolism in a south Indian population

    PubMed Central

    Rai, Padmalatha S; Murali, T. S; Vasudevan, T. G; Prasada, Shama K.; Bhagavath, Ashok Kumar; Pai, Pranita; Gopinath, P. M.; Satyamoorthy, K.

    2011-01-01

    BACKGROUND: Genetic variations represented as single nucleotide polymorphisms (SNPs) vary across the world population. This genetic polymorphism (such as SNPs) plays an important role in pharmacogenomics. SNPs that affects cellular metabolism, by altering the enzyme activity, have an important role in therapeutic outcome. Allele frequencies in number of clinically relevant SNPs within south Indian populations are not yet known. Hence, we genotyped randomly selected unrelated south Indian subjects from different locations of south India representing the heterogeneous ethnic background of the population. MATERIALS AND METHODS: Common variants of MTHFD1, TYMS, SHMT1, MTR, MTRR, CBS and SULT1A1 gene polymorphisms were screened from healthy unrelated south Indian volunteers. Genotypes were determined using RFLP analysis of polymerase chain reaction-amplified products and confirmed by DNA sequencing. Chi-square test was performed to test for deviation from the Hardy-Weinberg equilibrium for each locus. RESULTS: Gene allele frequency for several polymorphisms in our study differed significantly between the populations of other nations reported for several of the SNPs. These results demonstrate that the populations in different geographic regions may have widely varying genetic allele frequencies for clinically relevant SNPs. CONCLUSION: The present study reports, for the first time, the frequency distribution of MTHFD1, TYMS, SHMT1, MTR, MTRR, CBS and SULTIA1 gene polymorphisms in a south Indian population. Population-specific genetic polymorphism studies will help in practicing pharmacogenomic principles in the clinics. PMID:21747588

  9. Cytochrome P450 2E1 Gene Polymorphisms/Haplotypes and Anti-Tuberculosis Drug-Induced Hepatitis in a Chinese Cohort

    PubMed Central

    Tang, Shaowen; Lv, Xiaozhen; Zhang, Yuan; Wu, Shanshan; Yang, Zhirong; Xia, Yinyin; Tu, Dehua; Deng, Peiyuan; Ma, Yu; Chen, Dafang; Zhan, Siyan

    2013-01-01

    Objective The pathogenic mechanism of anti-tuberculosis (anti-TB) drug-induced hepatitis is associated with drug metabolizing enzymes. No tagging single-nucleotide polymorphisms (tSNPs) of cytochrome P450 2E1(CYP2E1) in the risk of anti-TB drug-induced hepatitis have been reported. The present study was aimed at exploring the role of tSNPs in CYP2E1 gene in a population-based anti-TB treatment cohort. Methods and Design A nested case-control study was designed. Each hepatitis case was 14 matched with controls by age, gender, treatment history, disease severity and drug dosage. The tSNPs were selected by using Haploview 4.2 based on the HapMap database of Han Chinese in Beijing, and detected by using TaqMan allelic discrimination technology. Results Eighty-nine anti-TB drug-induced hepatitis cases and 356 controls were included in this study. 6 tSNPs (rs2031920, rs2070672, rs915908, rs8192775, rs2515641, rs2515644) were genotyped and minor allele frequencies of these tSNPs were 21.9%, 23.0%, 19.1%, 23.6%, 20.8% and 44.4% in the cases and 20.9%, 22.7%, 18.9%, 23.2%, 18.2% and 43.2% in the controls, respectively. No significant difference was observed in genotypes or allele frequencies of the 6 tSNPs between case group and control group, and neither of haplotypes in block 1 nor in block 2 was significantly associated with the development of hepatitis. Conclusion Based on the Chinese anti-TB treatment cohort, we did not find a statistically significant association between genetic polymorphisms of CYP2E1 and the risk of anti-TB drug-induced hepatitis. None of the haplotypes showed a significant association with the development of hepatitis in Chinese TB population. PMID:23460870

  10. Ameliorating effect of betanin, a natural chromoalkaloid by modulating hepatic carbohydrate metabolic enzyme activities and glycogen content in streptozotocin - nicotinamide induced experimental rats.

    PubMed

    Dhananjayan, Indumathi; Kathiroli, Sujithra; Subramani, Srinivasan; Veerasamy, Vinothkumar

    2017-04-01

    Betanin, a chromoalkaloid of beetroot, has shown significant biological effects of antioxidants, anti-inflammatory and anticarcinogenic activities. So, we attempted to determine whether betanin (a natural pigment) would be protective against hyperglycemia in streptozotocin (STZ) - nicotinamide (NA) induced diabetic rats. Rats were injected with STZ (40mg/kgb.w.) 15 mins after the administration of NA (110mg/kgb.w.) by intraperitonially (i.p.) 30days for the induction of experimental diabetes mellitus. After 72h diabetic rats were treated with betanin orally at a doses of 10, 20 and 40mg/kg b.w., respectively in a dose dependent manner and glibenclamide (600μg/kgb.w.). The promising character of betanin against diabetic rats was evaluated by performing the various biochemical parameters and histomorphological changes in liver and pancreas. Among the three doses, 20mg/kgb.w. of betanin was able to positively regulate plasma glucose, insulin, glycosylated hemoglobin (HbA1c) and hemoglobin (Hb) levels by significantly increasing the activity of glycolytic enzyme (glucokinase and pyruvate kinase), glucose-6-phosphate dehydrogenase and significantly decreasing the activity of gluconeogenic enzymes (glucose-6-phosphatase and fructose-1,6-bisphosphatase) thereby increasing the glycogen content in the liver. We put forward that betanin could significantly restore the levels of carbohydrate metabolic key enzymes to near normal in diabetic rat. Immunohistochemical observation of pancreas revealed that betanin treated diabetic rats showed increased insulin immunoreactive β-cells, which confirmed the biochemical findings. Taken together, present study suggests that betanin modulates the carbohydrate metabolism and has beneficial effects in glucose homeostasis.

  11. The prevalence of TT virus and GB virus C/hepatitis G virus infection in individuals with raised liver enzymes but without HBV or HCV infection in Taiwan.

    PubMed Central

    Dai, C. Y.; Yu, M. L.; Chang, W. Y.; Tseng, C. H.; Hou, C.; Lin, Z. Y.; Chen, S. C.; Hsieh, M. Y.; Wang, L. Y.; Tsai, J. F.; Chuang, W. L.

    2002-01-01

    The prevalence of TT virus (TTV) and GB virus-C/hepatitis G virus (GBV-C/HGV) infection and the association with raised liver function tests in 546 Taiwanese with negative HBsAg, anti-HCV and HCV RNA was elucidated. They were tested for serum alanine aminotransferase (ALT), GBV-C/HGV RNA, anti-envelope protein 2 antibody (anti-E2) and TTV DNA. Direct sequencing and phylogenetic analyses were performed on 58 isolates for TTV genotype determination. The prevalence of TTV DNA, GBV-C/HGV RNA, anti-E2 and over all GBV-C/HGV exposure was 24.9, 3.4, 8.2 and 11.1%, respectively. Using uni- and multi-variate analyses, male gender and TTV viremia were associated significantly with raised ALT values. Sixty-nine percent of TTV isolates were deduced to be TTV genotype 1 and they had significantly lower mean age than genotype non-1 isolates. In the population, raised ALT may be related to male gender and be attributable to TTV infection but not to GBV-C/HGV among individuals with no evidence of current HBV and HCV infection. TTV genotype 1 is the most prevalent genotype and associated with younger age. PMID:12403107

  12. Application of chimeric mice with humanized liver for study of human-specific drug metabolism.

    PubMed

    Bateman, Thomas J; Reddy, Vijay G B; Kakuni, Masakazu; Morikawa, Yoshio; Kumar, Sanjeev

    2014-06-01

    Human-specific or disproportionately abundant human metabolites of drug candidates that are not adequately formed and qualified in preclinical safety assessment species pose an important drug development challenge. Furthermore, the overall metabolic profile of drug candidates in humans is an important determinant of their drug-drug interaction susceptibility. These risks can be effectively assessed and/or mitigated if human metabolic profile of the drug candidate could reliably be determined in early development. However, currently available in vitro human models (e.g., liver microsomes, hepatocytes) are often inadequate in this regard. Furthermore, the conduct of definitive radiolabeled human ADME studies is an expensive and time-consuming endeavor that is more suited for later in development when the risk of failure has been reduced. We evaluated a recently developed chimeric mouse model with humanized liver on uPA/SCID background for its ability to predict human disposition of four model drugs (lamotrigine, diclofenac, MRK-A, and propafenone) that are known to exhibit human-specific metabolism. The results from these studies demonstrate that chimeric mice were able to reproduce the human-specific metabolite profile for lamotrigine, diclofenac, and MRK-A. In the case of propafenone, however, the human-specific metabolism was not detected as a predominant pathway, and the metabolite profiles in native and humanized mice were similar; this was attributed to the presence of residual highly active propafenone-metabolizing mouse enzymes in chimeric mice. Overall, the data indicate that the chimeric mice with humanized liver have the potential to be a useful tool for the prediction of human-specific metabolism of xenobiotics and warrant further investigation.

  13. Concentration dependent effects of tobacco particulates from different types of cigarettes on expression of drug metabolizing proteins, and benzo(a)pyrene metabolism in primary normal human oral epithelial cells

    PubMed Central

    Sacks, Peter G.; Zhao, Zhong-Lin; Kosinska, Wieslawa; Fleisher, Kenneth E.; Gordon, Terry; Guttenplan, Joseph B.

    2011-01-01

    The ability of tobacco smoke (TS) to modulate phase I and II enzymes and affect metabolism of tobacco carcinogens is likely an important factor in its carcinogenicity. For the first time several types of TS particulates (TSP) were compared in different primary cultured human oral epithelial cells (NOE) for their abilities to affect metabolism of the tobacco carcinogen, (BaP) to genotoxic products, and expression of drug metabolizing enzymes. TSP from, reference filtered (2RF4), mentholated (MS), reference unfiltered, (IR3), ultra low tar (UL), and cigarettes that primarily heat tobacco (ECL) were tested. Cells pretreated with TSP concentrations of 0.2 – 10 µg/ml generally showed increased rates of BaP metabolism; those treated with TSP concentrations above 10 µg/ml showed decreased rates. Effects of TSPs were similar when expressed on a weight basis. Weights of TSP/cigarette varied in the order: MS ≈ IR3 > 2RF4 > ECL > UL. All TSPs induced the phase I proteins, cytochrome P450 1A1 (CYP1A1) and 1B1 (CYP1B1), phase II proteins, NAD(P)H dehydrogenase quinone 1 (NQO1), and microsomal glutathione S-transferase 1 (MGST1), and additionally, hydroxysteroid (17-beta) dehydrogenase 2 (HSD17B2), as assessed by qRT-PCR. The pattern of gene induction at probable physiological levels favored activation over detoxification. PMID:21722697

  14. Concentration dependent effects of tobacco particulates from different types of cigarettes on expression of drug metabolizing proteins, and benzo(a)pyrene metabolism in primary normal human oral epithelial cells.

    PubMed

    Sacks, Peter G; Zhao, Zhong-Lin; Kosinska, Wieslawa; Fleisher, Kenneth E; Gordon, Terry; Guttenplan, Joseph B

    2011-09-01

    The ability of tobacco smoke (TS) to modulate phase I and II enzymes and affect metabolism of tobacco carcinogens is likely an important factor in its carcinogenicity. For the first time several types of TS particulates (TSP) were compared in different primary cultured human oral epithelial cells (NOE) for their abilities to affect metabolism of the tobacco carcinogen, (BaP) to genotoxic products, and expression of drug metabolizing enzymes. TSP from, reference filtered (2RF4), mentholated (MS), reference unfiltered, (IR3), ultra low tar (UL), and cigarettes that primarily heat tobacco (ECL) were tested. Cells pretreated with TSP concentrations of 0.2-10 μg/ml generally showed increased rates of BaP metabolism; those treated with TSP concentrations above 10 μg/ml showed decreased rates. Effects of TSPs were similar when expressed on a weight basis. Weights of TSP/cigarette varied in the order: MS≈IR3>2RF4>ECL>UL. All TSPs induced the phase I proteins, cytochrome P450 1A1 (CYP1A1) and 1B1 (CYP1B1), phase II proteins, NAD(P)H dehydrogenase quinone 1 (NQO1), and microsomal glutathione S-transferase 1 (MGST1), and additionally, hydroxysteroid (17-beta) dehydrogenase 2 (HSD17B2), as assessed by qRT-PCR. The pattern of gene induction at probable physiological levels favored activation over detoxification.

  15. Contributions of human enzymes in carcinogen metabolism.

    PubMed

    Rendic, Slobodan; Guengerich, F Peter

    2012-07-16

    Considerable support exists for the roles of metabolism in modulating the carcinogenic properties of chemicals. In particular, many of these compounds are pro-carcinogens that require activation to electrophilic forms to exert genotoxic effects. We systematically analyzed the existing literature on the metabolism of carcinogens by human enzymes, which has been developed largely in the past 25 years. The metabolism and especially bioactivation of carcinogens are dominated by cytochrome P450 enzymes (66% of bioactivations). Within this group, six P450s--1A1, 1A2, 1B1, 2A6, 2E1, and 3A4--accounted for 77% of the P450 activation reactions. The roles of these P450s can be compared with those estimated for drug metabolism and should be considered in issues involving enzyme induction, chemoprevention, molecular epidemiology, interindividual variations, and risk assessment.

  16. Contributions of Human Enzymes in Carcinogen Metabolism

    PubMed Central

    Rendic, Slobodan; Guengerich, F. Peter

    2012-01-01

    Considerable support exists for roles of metabolism in modulating the carcinogenic properties of chemicals. In particular, many of these compounds are procarcinogens that require activation to electrophilic forms to exert genotoxic effects. We systematically analyzed the existing literature on metabolism of carcinogens by human enzymes, which has been developed largely in the past 25 years. The metabolism and especially bioactivation of carcinogens are dominated by cytochrome P450 enzymes (66% of bioactivations). Within this group, six P450s—1A1, 1A2, 1B1, 2A6, 2E1, and 3A4—accounted for 77% of the P450 activation reactions. The roles of these P450s can be compared with those estimated for drug metabolism and should be considered in issues involving enzyme induction, chemoprevention, molecular epidemiology, inter-individual variations, and risk assessment. PMID:22531028

  17. Influence of Various Polymorphic Variants of Cytochrome P450 Oxidoreductase (POR) on Drug Metabolic Activity of CYP3A4 and CYP2B6

    PubMed Central

    Naranmandura, Hua; Zeng, Su; Chen, Shu Qing

    2012-01-01

    Cytochrome P450 oxidoreductase (POR) is known as the sole electron donor in the metabolism of drugs by cytochrome P450 (CYP) enzymes in human. However, little is known about the effect of polymorphic variants of POR on drug metabolic activities of CYP3A4 and CYP2B6. In order to better understand the mechanism of the activity of CYPs affected by polymorphic variants of POR, six full-length mutants of POR (e.g., Y181D, A287P, K49N, A115V, S244C and G413S) were designed and then co-expressed with CYP3A4 and CYP2B6 in the baculovirus-Sf9 insect cells to determine their kinetic parameters. Surprisingly, both mutants, Y181D and A287P in POR completely inhibited the CYP3A4 activity with testosterone, while the catalytic activity of CYP2B6 with bupropion was reduced to approximately ∼70% of wild-type activity by Y181D and A287P mutations. In addition, the mutant K49N of POR increased the CLint (Vmax/Km) of CYP3A4 up to more than 31% of wild-type, while it reduced the catalytic efficiency of CYP2B6 to 74% of wild-type. Moreover, CLint values of CYP3A4-POR (A115V, G413S) were increased up to 36% and 65% of wild-type respectively. However, there were no appreciable effects observed by the remaining two mutants of POR (i.e., A115V and G413S) on activities of CYP2B6. In conclusion, the extent to which the catalytic activities of CYP were altered did not only depend on the specific POR mutations but also on the isoforms of different CYP redox partners. Thereby, we proposed that the POR-mutant patients should be carefully monitored for the activity of CYP3A4 and CYP2B6 on the prescribed medication. PMID:22719896

  18. Hepatitis C: Treatment

    MedlinePlus

    ... Public Home » Hepatitis C » Hepatitis C Treatment Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... Enter ZIP code here Enter ZIP code here Hepatitis C Treatment for Veterans and the Public Treatment ...

  19. Hepatitis A

    MedlinePlus

    ... an inflammation of the liver. One type, hepatitis A, is caused by the hepatitis A virus (HAV). The disease spreads through contact with ... washed in untreated water Putting into your mouth a finger or object that came into contact with ...

  20. Hepatitis B

    MedlinePlus

    ... commonly used with viral hepatitis and related conditions. Web Resources American Liver Foundation A national nonprofit organization ... other liver diseases through research, education, and advocacy. Web site features a database directory of hepatitis clinical ...

  1. Hepatitis B

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000279.htm Hepatitis B To use the sharing features on this page, please enable JavaScript. Hepatitis B is irritation and swelling (inflammation) of the ...

  2. Autoimmune hepatitis

    MedlinePlus

    Lupoid hepatitis; Chronic acute liver disease ... This form of hepatitis is an autoimmune disease . The body's immune system cannot tell the difference between healthy body tissue and harmful, outside ...

  3. Hepatitis B

    MedlinePlus

    ... times more infectious than HIV. Which adults need hepatitis B vaccine? Any sexually active adult who is not in ... share needles, syringes, or other drug-injection equipment. Hepatitis B vaccine is available alone or in a combination with ...

  4. Enzyme stereospecificity as a powerful tool in searching for new enzymes.

    PubMed

    Skarydová, Lucie; Skarka, Adam; Solich, Petr; Wsól, Vladimír

    2010-07-01

    Chirality is a ubiquitous feature present in all biological systems that plays a very important role in many processes. Drug metabolism is one of these and is the subject of this review. Chiral drugs can be metabolized without changes in their chiral characteristics, but also their biotransformation may give rise to a new chiral center. On the other hand, prochiral drugs are always metabolized to chiral metabolites. The ratio of formed enantiomers/diastereoisomers is the constant known as enzyme stereospecificity, and this is as important a characteristic for each enzyme-substrate pair as is the Michaelis constant. Drugs are often substrates for multiple biotransformation enzymes, and all enzymes involved may metabolize a chiral or prochiral drug with different stereospecificity so that variant enantiomer ratios are achieved. Enzyme stereospecificity of whole cell fraction is the sum of the stereospecificities of all enzymes participating in metabolism of a substrate. Differing stereospecificities in the metabolism of a drug between whole cell fraction and enzymes point to the contribution of other enzymes. Using several drugs as examples, this review shows that enzyme stereospecificity can serve as a powerful tool in searching for new biotransformation enzymes. Although it is not often used in this way, it is clear that this is possible. There are today drugs with well-known chiral metabolism, but, inasmuch as many xenobiotics are poorly characterized in terms of chiral metabolism, enzyme stereospecificity could be widely utilized in researching such substances.

  5. Transcription factor-mediated regulation of carboxylesterase enzymes in livers of mice.

    PubMed

    Zhang, Youcai; Cheng, Xingguo; Aleksunes, Lauren; Klaassen, Curtis D

    2012-06-01

    The induction of drug-metabolizing enzymes by chemicals is one of the major reasons for drug-drug interactions. In the present study, the regulation of mRNA expression of one arylacetamide deacetylase (Aadac) and 11 carboxylesterases (Cess) by 15 microsomal enzyme inducers (MEIs) was examined in livers of male C57BL/6 mice. The data demonstrated that Aadac mRNA expression was suppressed by three aryl hydrocarbon receptor (AhR) ligands, two constitutive androstane receptor (CAR) activators, two pregnane X receptor (PXR) ligands, and one nuclear factor erythroid 2-related factor 2 (Nrf2) activator. Ces1 subfamily mRNA expression was not altered by most of the MEIs, whereas Ces2 subfamily mRNA was readily induced by the activators of CAR, PXR, and Nrf2 but not by peroxisome proliferator-activated receptor α activators. Studies using null mice demonstrated that 1) AhR was required for the 2,3,7,8-tetrachlorodibenzo-p-dioxin-mediated suppression of Aadac and Ces3a; 2) CAR was involved in the 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene-mediated induction of Aadac, Ces2c, Ces2a, and Ces3a; 3) PXR was required for the pregnenolone-16α-carbonitrile-mediated induction of Aadac, Ces2c, and Ces2a; 4) Nrf2 was required for the oltipraz-mediated induction of Ces1g and Ces2c; and 5) PXR was not required for the DEX-mediated suppression of Cess in livers of mice. In conclusion, the present study systematically investigated the regulation of Cess by MEIs in livers of mice and demonstrated that MEIs modulated mRNA expression of mouse hepatic Cess through the activation of AhR, CAR, PXR, and/or Nrf2 transcriptional pathways.

  6. Transcription Factor-Mediated Regulation of Carboxylesterase Enzymes in Livers of Mice

    PubMed Central

    Zhang, Youcai; Cheng, Xingguo; Aleksunes, Lauren

    2012-01-01

    The induction of drug-metabolizing enzymes by chemicals is one of the major reasons for drug-drug interactions. In the present study, the regulation of mRNA expression of one arylacetamide deacetylase (Aadac) and 11 carboxylesterases (Cess) by 15 microsomal enzyme inducers (MEIs) was examined in livers of male C57BL/6 mice. The data demonstrated that Aadac mRNA expression was suppressed by three aryl hydrocarbon receptor (AhR) ligands, two constitutive androstane receptor (CAR) activators, two pregnane X receptor (PXR) ligands, and one nuclear factor erythroid 2-related factor 2 (Nrf2) activator. Ces1 subfamily mRNA expression was not altered by most of the MEIs, whereas Ces2 subfamily mRNA was readily induced by the activators of CAR, PXR, and Nrf2 but not by peroxisome proliferator-activated receptor α activators. Studies using null mice demonstrated that 1) AhR was required for the 2,3,7,8-tetrachlorodibenzo-p-dioxin–mediated suppression of Aadac and Ces3a; 2) CAR was involved in the 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene–mediated induction of Aadac, Ces2c, Ces2a, and Ces3a; 3) PXR was required for the pregnenolone-16α-carbonitrile–mediated induction of Aadac, Ces2c, and Ces2a; 4) Nrf2 was required for the oltipraz-mediated induction of Ces1g and Ces2c; and 5) PXR was not required for the DEX-mediated suppression of Cess in livers of mice. In conclusion, the present study systematically investigated the regulation of Cess by MEIs in livers of mice and demonstrated that MEIs modulated mRNA expression of mouse hepatic Cess through the activation of AhR, CAR, PXR, and/or Nrf2 transcriptional pathways. PMID:22429928

  7. Inhibition of human cytochrome P450 enzymes by Bacopa monnieri standardized extract and constituents.

    PubMed

    Ramasamy, Seetha; Kiew, Lik Voon; Chung, Lip Yong

    2014-02-24

    Bacopa monnieri and the constituents of this plant, especially bacosides, possess various neuropharmacological properties. Like drugs, some herbal extracts and the constituents of their extracts alter cytochrome P450 (CYP) enzymes, causing potential herb-drug interactions. The effects of Bacopa monnieri standardized extract and the bacosides from the extract on five major CYP isoforms in vitro were analyzed using a luminescent CYP recombinant human enzyme assay. B. monnieri extract exhibited non-competitive inhibition of CYP2C19 (IC50/Ki = 23.67/9.5 µg/mL), CYP2C9 (36.49/12.5 µg/mL), CYP1A2 (52.20/25.1 µg/mL); competitive inhibition of CYP3A4 (83.95/14.5 µg/mL) and weak inhibition of CYP2D6 (IC50 = 2061.50 µg/mL). However, the bacosides showed negligible inhibition of the same isoforms. B. monnieri, which is orally administered, has a higher concentration in the gut than the liver; therefore, this herb could exhibit stronger inhibition of intestinal CYPs than hepatic CYPs. At an estimated gut concentration of 600 µg/mL (based on a daily dosage of 300 mg/day), B. monnieri reduced the catalytic activities of CYP3A4, CYP2C9 and CYP2C19 to less than 10% compared to the total activity (without inhibitor = 100%). These findings suggest that B. monnieri extract could contribute to herb-drug interactions when orally co-administered with drugs metabolized by CYP1A2, CYP3A4, CYP2C9 and CYP2C19.

  8. Diagnostic value of anti-smooth muscle antibodies and liver enzymes in differentiation of extrahepatic biliary atresia and idiopathic neonatal hepatitis

    PubMed Central

    Rafeey, Mandana; Saboktakin, Lida; Hasani, Jamshid Shoa; Naghashi, Shahnaz

    2016-01-01

    Background: We aimed to evaluate the diagnostic value of anti-smooth muscle antibodies (ASMA) and two liver markers (gamma-glutamyl transpeptidase [GGT] and alkaline phosphatase [ALP]) for differentiating between patients with extrahepatic biliary atresia (EHBA) and idiopathic neonatal hepatitis (INH). Materials and Methods: During April 2010–2011, all infants at 2 weeks of age who were diagnosed with cholestasis and admitted to Children's Hospital of Tabriz were enrolled. Based on the results of physical examination, laboratory, imaging and pathological studies, neonates were divided into two groups (EHBA and INH). Receiver operating characteristics analysis was used to define sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for ASMA, GGT and ALP. Results: Thirty neonates with cholestasis (18 with EHBA and 12 with INH) and mean age of 54.66 ± 25.86 days were enrolled. Total and direct bilirubin, serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase and ASMA titres were highly not significant (P > 0.05) in patients with INH. GGT (P = 0.008) and ALP (P = 0.01) had statistically significant differences that were higher in patients with EHBA. The sensitivity, specificity, PPV and NPV, accuracy, LR+ and LR− of SMA in differentiating cases with BA were 66.7%, 75%, 80% 60%, 70%, 2.68 and 0.44, respectively. For GGT, the values were 88.9%, 66.7%, 80%, 80%, 79.1%, 3.08 and 0.31, respectively. Finally, for ALP, the values were 77.8%, 75%, 82.4%, 69.2%, 80%, 2.66 and 0.24, respectively. Conclusion: Our study showed that ASMA may be a useful biomarker for differentiation of EHBA from INH. Further studies with larger samples are recommended for confirming the results of this study. PMID:27251654

  9. Effect of Turmeric and Carrot Seed Extracts on Serum Liver Biomarkers and Hepatic Lipid Peroxidation, Antioxidant Enzymes and Total Antioxidant Status in Rats

    PubMed Central

    Rezaei-Moghadam, Adel; Mohajeri, Daryoush; Rafiei, Behnam; Dizaji, Rana; Azhdari, Asghar; Yeganehzad, Mahdi; Shahidi, Maryamossadat; Mazani, Mohammad

    2012-01-01

    Introduction Pathogenic role of free radicals are well known in various metabolic diseases. They originate from internal and external sources of body. Essential roles of antioxidant defense system for cellular redox regulation and free radical scavenging activity were described in this study. Many in vitro investigations have shown that turmeric (TE) and carrot seed extract (CSE) exhibits to possess antioxidant activities. In this study, we evaluated the antioxidant potentials of ethanolic TE and CSE based on in vivo experiment in the rats. Methods Animals were assigned to six groups: the 1st and 2nd groups were control groups and 2nd group received 0.2 ml dimethyl sulphoxide as vehicle treated group; other four experimental groups received different doses of TE (100, 200 mg/kg b.w.) and CSE (200, 400 mg/kg b.w.) by gavages, respectively for a period of one month. The indicators of oxidative stress, lipids peroxidation, markers of hepatocyte injury and biliary function markers were measured. Results The levels of superoxide dismutase, catalase, and glutathione peroxidase were significantly stimulated in the hepatic tissue of treatment groups. The malondialdehyde contents of liver tissue were significantly reduced in the groups fed with TE and CSE. Serum levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase, in treated groups were found to be significantly decreased, whereas albumin and total protein increased as compared to the control groups (P<0.05). Conclusion this study showed that the regular intake of TE and CSE through the diet can improve antioxidant status and inhibit peroxidation activity in the liver tissue so that using these extracts may protect tissue oxidative stress. PMID:23678453

  10. Successful treatment of severe refractory lupus hepatitis with mycophenolate mofetil.

    PubMed

    Tagawa, Y; Saito, T; Takada, K; Kawahata, K; Kohsaka, H

    2016-04-01

    Systemic lupus erythematosus-related hepatitis, known as lupus hepatitis, is a rare manifestation of systemic lupus erythematosus, and is usually subclinical with mild abnormalities of serum liver enzymes. While cases with clinically significant and refractory lupus hepatitis are uncommon, treatment options for lupus hepatitis are to be established. Here, we report the case of a 45-year-old man with progressive lupus hepatitis accompanied by autoimmune haemolytic anaemia. Lupus hepatitis of this patient was refractory to tacrolimus, azathioprine and cyclophosphamide, but was successfully treated by mycophenolate mofetil. Mycophenolate mofetil might be an effective therapeutic option for refractory lupus hepatitis.

  11. Circadian regulation of the hepatic endobiotic and xenobitoic detoxification pathways: the time matters.

    PubMed

    Zmrzljak, Ursula Prosenc; Rozman, Damjana

    2012-04-16

    Metabolic processes have to be regulated tightly to prevent waste of energy and to ensure sufficient detoxification. Most anabolic processes operate in a timely manner when energy intake is the highest, while catabolism takes place in energy spending periods. Endobiotic and xenobiotic metabolism are therefore under circadian control. Circadian regulation is mediated through the suprachiasmatic nucleus (SCN), a master autonomous oscillator of the brain. Although many peripheral organs have their own oscillators, the SCN is important in orchestrating and entraining organs according to the environmental light cues. However, light is not the only signal for entrainment of internal clocks. For endobiotic and xenobitoic detoxification pathways, the food composition and intake regime are equally important. The rhythm of the liver as an organ where the major metabolic pathways intersect depends on SCN signals, signals from endocrine tissues, and, importantly, the type and time of feeding or xenobiotics ingestion. Several enzymes are involved in detoxification processes. Phase I is composed mainly of cytochromes P450, which are regulated by nuclear receptors. Phase II enzymes modify the phase I metabolites, while phase III includes membrane transporters responsible for the elimination of modified xenobiotics. Phases I-III of drug metabolism are under strong circadian regulation, starting with the drug-sensing nuclear receptors and ending with drug transporters. Disturbed circadian regualtion (jet-lag, shift work, and dysfunction of core clock genes) leads to changed periods of activity, sleep disorders, disturbed glucose homeostasis, breast or colon cancer, and metabolic syndrome. As many xenobiotics influence the circadian rhythm of the liver, bad drug administration timing can worsen the above listed effects. This review will cover the major hepatic circadian regulation of endogenous and xenobiotic metabolic pathways and will provide examples of how good timing of drug

  12. Hepatitis C

    MedlinePlus

    ... an inflammation of the liver. One type, hepatitis C, is caused by the hepatitis C virus (HCV). It usually spreads through contact with ... childbirth. Most people who are infected with hepatitis C don't have any symptoms for years. If ...

  13. Building a 3D Virtual Liver: Methods for Simulating Blood Flow and Hepatic Clearance on 3D Structures

    PubMed Central

    Rezania, Vahid; Tuszynski, Jack

    2016-01-01

    In this paper, we develop a spatio-temporal modeling approach to describe blood and drug flow, as well as drug uptake and elimination, on an approximation of the liver. Extending on previously developed computational approaches, we generate an approximation of a liver, which consists of a portal and hepatic vein vasculature structure, embedded in the surrounding liver tissue. The vasculature is generated via constrained constructive optimization, and then converted to a spatial grid of a selected grid size. Estimates for surrounding upscaled lobule tissue properties are then presented appropriate to the same grid size. Simulation of fluid flow and drug metabolism (hepatic clearance) are completed using discretized forms of the relevant convective-diffusive-reactive partial differential equations for these processes. This results in a single stage, uniformly consistent method to simulate equations for blood and drug flow, as well as drug metabolism, on a 3D structure representative of a liver. PMID:27649537

  14. Disposition of hexobarbital in intra- and extrahepatic cholestasis in man and the influence of drug metabolism-inducing agents.

    PubMed

    Richter, E; Breimer, D D; Zilly, W

    1980-01-01

    The pharmacokinetics of intravenously infused hexobarbital was studied in 10 patients with intrahepatic cholestasis and in 9 with extrahepatic biliary obstruction. The results were compared with those obtained in 16 healthy young volunteers and 5 older patients with normal liver function. After infusion, the plasma concentrations showed a rapid initial decline (alpha-phase) and subsequently a slower decrease (beta-phase). The half-life of a latter phase was 323 +/- 84 min in the healthy group, 357 +/- 151 min in the patients with intrahepatic cholestasis and 344 +/- 115 min in the group with biliary obstruction; the clearances were 3.41 +/- 0.90, 4.08 +/- 1.95 and 3.81 +/- 1.97 ml x min-1 x kg-1, respectively. The differences were not statistically significant. The mean volume of the central compartment of distribution and the steady state volume of distribution were not significantly different. In two patients hexobarbital clearance during cholestasis was greater than after it had subsided. After treatment of 11 patients with cholestasis with drug metabolism-inducing agents (phenobarbital, rifampicin or phenytoin), the half-life of hexobarbital was significantly shortened and the mean value of hexobarbital clearance was more than doubled.

  15. Model of complex chiral drug metabolic systems and numerical simulation of the remaining chirality toward analysis of dynamical pharmacological activity.

    PubMed

    Ogino, Yoshiyuki; Asahi, Toru

    2015-05-21

    In this study, systems of complicated pathways involved in chiral drug metabolism were investigated. The development of chiral drugs resulted in significant improvement in the remedies available for the treatment of various severe sicknesses. Enantiopure drugs undergo various biological transformations that involve chiral inversion and thus result in the generation of multiple enantiomeric metabolites. Identification of the specific active substances determining a given drug׳s efficacy among such a mixture of different metabolites remains a challenge. To comprehend this complexity, we constructed a mathematical model representing the complicated metabolic pathways simultaneously involving chiral inversion. Moreover, this model is applied to the metabolism of thalidomide, which has recently been revived as a potentially effective prescription drug for a number of intractable diseases. The numerical simulation results indicate that retained chirality in the metabolites reflects the original chirality of the unmetabolized drug, and a higher level of enantiomeric purity is preserved during spontaneous degradation. In addition, chirality remaining after equilibration is directly related to the rate constant not only for chiral inversion but also for generation and degradation. Furthermore, the retention of chirality is quantitatively predictable using this combination of kinetic parameters. Our simulation results well explain the behavior of thalidomide in the practical biological experimental data. Therefore, this model promises a comprehensive understanding of dynamic metabolic systems involving chiral drugs that express multiple enantiospecific drug efficacies.

  16. Development of a fluorescent microbead-based immunoassay for the detection of hepatitis E virus IgG antibodies in pigs and comparison to an enzyme-linked immunoassay.

    PubMed

    Owolodun, Olajide A; Giménez-Lirola, Luis G; Gerber, Priscilla F; Sanford, Brenton J; Feagins, Alicia R; Meng, Xiang-Jin; Halbur, Patrick G; Opriessnig, Tanja

    2013-11-01

    Swine hepatitis E virus (HEV) is a zoonotic virus and pigs are considered as an important reservoir. Swine HEV infection is widespread and most pig herds are infected. Humans can be infected with swine HEV via consumption of undercooked pork or through direct contact with infected pigs. To minimize the risk of zoonotic transmission, sensitive tools to assess the HEV infection status of pigs and pork products are needed. The objective of this study was to develop a fluorescent microbead-based immunoassay (FMIA) for the detection of IgG antibodies against swine HEV and compare it to an in-house enzyme-linked immunoassay (ELISA). Three sets of samples were utilized: (A) samples from pigs infected experimentally with different strains of HEV (positive controls, n=72), (B) samples from known HEV-negative pigs (negative controls, n=62) and (C) samples from pigs of unknown HEV infection status (n=182). All samples were tested by both ELISA and FMIA. The results on the experimental samples with known HEV exposure indicate that both assays have a specificity of 100% while the sensitivity ranges from 84.6% (ELISA) to 92.3% (FMIA). The overall prevalence of HEV IgG antibodies in field samples from pigs with unknown HEV exposure was 21.9% (40/182) for the ELISA and 21.4% (39/182) for the FMIA. The two assays had an almost perfect overall agreement (Kappa=0.92).

  17. Measurements in international units of antibody to hepatitis B surface antigen(anti-HBs) after immunization with a yeast-derived, subtype adr hepatitis B vaccine are considerably different between chemiluminescent immunoassay (CLIA) and chemiluminescent enzyme immunoassay (CLEIA).

    PubMed

    Ogata, Norio

    2006-04-01

    The worldwide consensus of the minimum protective anti-HBs level against HBV infection is 10 mIU/mL on assays standardized by the World Health Organization (WHO) reference preparations. To investigate whether this value could be applied to recipients of yeast-derived recombinant HB vaccine containing the major surface protein of subtype adr (Bimmugen, Astellas Pharmaceutical, Tokyo), we compared anti-HBs measurements between chemiluminescent immunoassay (CLIA) (Architect Ausab, Abbott Japan, Tokyo) and chemiluminescent enzyme immunoassay (CLEIA) (Lumipulse Forte, Fujirebio, Tokyo) in given serum samples obtained from the vaccinees. The vaccine and the two assay methods are currently in a wide use in Japan. The study included 300 medical students who completed a standard vaccination course (0, 1 and 6 months). Serum samples obtained 1 month or 13 months after completing the vaccination were simultaneously tested for anti-HBs by CLIA and CLEIA. In 147 samples with quantifiable values on both CLIA and CLEIA (10 to 1000 mIU/mL) the geometric mean titer on CLEIA (225.0 mIU/mL) was significantly higher than that on CLIA (94.5 mIU/mL) (p < 0.0001). Of 26 subjects with CLIA measurements below 10 mIU/mL, 15 samples (57.7%) showed CLEIA measurements more than 10 mIU/mL. Thus, in the subtype adr-vaccinees CLEIA demonstrated considerably high serum anti-HBs measurements compared to CLIA and discordance in determining critical anti-HBs level of 10 mIU/mL was observed in more than half the samples. This suggests that the minimum HBV-protective anti HBs titer of 10 mIU/mL is difficult to be introduced to Japan where subtype adr-HB vaccines or -HBV infection are prevalent, unless characteristics of assay methods are carefully evaluated.

  18. Syzygium cumini seed extract protects the liver against lipid peroxidation with concurrent amelioration of hepatic enzymes and lipid profile of alcoholic rats.

    PubMed

    Hossain, Shahdat; Chowdhury, Imrul Hasan; Basunia, Mafroz Ahmed; Nahar, Taslima; Rahaman, Asiqur; Choudhury, Bazlur Karim; Choudhuri, Shahabuddin Kabir; Mahmud, Ishtiaq; Uddin, Borhan

    2011-01-01

    The in vitro oxidative stress induced by ethanol/Fenton's reaction in rat liver homogenates decreased significantly in the presence of Syzygium cumini seed extract, suggesting the protective effect of the seed extract against the oxidative stress in liver. To corroborate the in vitro effects by an in vivo experiment, 24 rats were divided into four groups: control, S. cumini seed-extract-administered (SE), 15% ethanol-fed (Alc) and Alc+SE rats. The oral administration of the extract (400 mg/kg BW.day) for 7 weeks significantly decreased the levels of liver LPO in the Alc+SE rats, suggesting that S. cumini seed not only obstructed the in vitro free radical production and subsequent oxidative stress, but also inhibited their in vivo formation. The oral administration of extract also reduced the enzyme activities of serum gammaglutamyl transferase, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase and the levels of serum creatinine and blood urea nitrogen, serum/liver triglycerides and total cholesterol of the alcoholic rats. The levels of fecal cholesterol were increased by the extract. Fatty degenerations in liver and kidney were absent with S. cumini seed extract treatment. The results suggest that S. cumini seed may be a potential therapy for alcoholics and related dysfunctions by restraining oxidative stress.

  19. Hepatitis Vaccines

    PubMed Central

    Ogholikhan, Sina; Schwarz, Kathleen B.

    2016-01-01

    Viral hepatitis is a serious health problem all over the world. However, the reduction of the morbidity and mortality due to vaccinations against hepatitis A and hepatitis B has been a major component in the overall reduction in vaccine preventable diseases. We will discuss the epidemiology, vaccine development, and post-vaccination effects of the hepatitis A and B virus. In addition, we discuss attempts to provide hepatitis D vaccine for the 350 million individuals infected with hepatitis B globally. Given the lack of a hepatitis C vaccine, the many challenges facing the production of a hepatitis C vaccine will be shown, along with current and former vaccination trials. As there is no current FDA-approved hepatitis E vaccine, we will present vaccination data that is available in the rest of the world. Finally, we will discuss the existing challenges and questions facing future endeavors for each of the hepatitis viruses, with efforts continuing to focus on dramatically reducing the morbidity and mortality associated with these serious infections of the liver. PMID:26978406

  20. Feature Hepatitis: Hepatitis Can Strike Anyone

    MedlinePlus

    ... Navigation Bar Home Current Issue Past Issues Feature Hepatitis Hepatitis Can Strike Anyone Past Issues / Spring 2009 Table ... from all walks of life are affected by hepatitis, especially hepatitis C, the most common form of ...

  1. Hepatitis A through E (Viral Hepatitis)

    MedlinePlus

    ... travelers How can hepatitis B be prevented? The hepatitis B vaccine offers the best protection. All infants and unvaccinated ... should receive hepatitis B immune globulin and the hepatitis B vaccine within 12 hours of birth to help prevent ...

  2. Hepatitis C Test

    MedlinePlus

    ... Hepatitis C Antibody; Anti-HCV; HCV-PCR; HCV-RNA; Hepatitis C Viral Load Formal name: Viral Hepatitis C Antibody Screen; Viral Hepatitis C RNA by PCR; Hepatitis C Virus Genotype Related tests: ...

  3. Alcohol and Hepatitis

    MedlinePlus

    ... Home » Living with Hepatitis » Daily Living: Alcohol Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... Alcohol for Veterans and the Public Alcohol and Hepatitis: Entire Lesson Overview Alcohol is one of the ...

  4. Hepatitis C: Clinical Trials

    MedlinePlus

    ... and Public Home » Hepatitis C » Treatment Decisions Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... can I find out about participating in a hepatitis C clinical trial? Many trials are being conducted ...

  5. Hepatitis (For Parents)

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old Hepatitis KidsHealth > For Parents > Hepatitis Print A A A ... to Call the Doctor en español Hepatitis About Hepatitis The word hepatitis simply means an inflammation of ...

  6. Travelers' Health: Hepatitis B

    MedlinePlus

    ... Chapter 3 - Hepatitis A Chapter 3 - Hepatitis C Hepatitis B Francisco Averhoff INFECTIOUS AGENT Hepatitis B is ... their exposures. Map 3-04. Prevalence of chronic hepatitis B virus infection among adults PDF Version (printable) ...

  7. Potential roles of placental human beta-defensin-3 and apolipoprotein B mRNA-editing enzyme catalytic polypeptide 3G in prevention of intrauterine transmission of hepatitis B virus.

    PubMed

    Bai, Xiaoxia; Tian, Ting; Wang, Peng; Yang, Xiaofu; Wang, Zhengping; Dong, Minyue

    2015-03-01

    Approximately 5% of newborns were infected by hepatitis B virus (HBV) via intrauterine transmission and this is the main reason for high prevalence of HBV in endemic regions. However, the mechanisms by which intrauterine transmission is avoided in most cases remain elusive and placental natural anti-microbial factors may play a role in the prevention of HBV intrauterine transmission. The expression levels of human β-defensin-3 (HBD-3), apolipoprotein B mRNA-editing enzyme catalytic polypeptide 3G (A3G) and mannose binding lectin (MBL) were determined in the placenta of 30 HBV-seronegative pregnant women (controls), 7 HBV-seropositive pregnant women with infants infected via intrauterine transmission (infected group) and 30 HBV-seropositive pregnant women with non-infected infants (non-infected group). The expression of HBD-3, A3G, and MBL of placental trophoblast cell line Swan71 was determined after exposed to HBV. There were significant differences in placental HBD-3 and A3G levels among three groups, but the expression of MBL did not significantly differ. The expressions of HBD-3 and A3G were higher in non-infected group than controls and infected group, but not significantly different between infected group and controls. The exposure to HBV increased significantly the expression of HBD-3, A3G, and MBL by Swan 71. It may be concluded HBV up-regulates HBD-3 and A3G expression in vivo and in vitro in placental trophoblast and lack of this up-regulation is possibly associated with intrauterine transmission of HBV.

  8. Potent induction of rat liver microsomal, drug-metabolizing enzymes by 2,3,3',4,4',5-hexabromobiphenyl, a component of fireMaster.

    PubMed

    Robertson, L W; Parkinson, A; Bandiera, S; Safe, S

    1981-04-01

    The multistep synthesis and purification of 2,3,3',4,4',5-hexabromobiphenyl (HBBp) is described. Capillary gas chromatography revealed that HBBp comprises 0.05% of the industrial polybrominated biphenyl (PBB) mixture, fireMaster BP-6 (lot 7062). When administered to immature male Wistar rats, HBBp caused a dose-dependent increase in (a) the activity of benzo[a]pyrene (B[a]P) hydroxylase (AHH) and 4-chlorobiphenyl (4-CBP) hydroxylase and (b) the concentration of cytochrome P-450. Sodium dodecyl sulfate (SDS)-gel electrophoresis indicated that these increases in cytochrome P-450 and cytochrome P-450-dependent monooxygenase activities were accompanied by a dose-dependent intensification of a protein of relative molecular weight (Mr) 55 000 which comigrated with the major 3-methylcholanthrene(MC)-inducible form of cytochrome P-450 (i.e., cytochrome P-448). Like MC, but in contrast to phenobarbitone (PB), HBBp competitively displaced 2,3,7,8-[3H]tetrachlorodibenzo-p-dioxin ([3H]-TCDD) from the cytosolic protein thought to be the receptor for cytochrome P-448 induction. The results indicate that HBBp is a potent inducer of cytochrome P-448 and as such is the third MC-type inducer identified in fireMaster BP-6.

  9. Toward a clinical practice guide in pharmacogenomics testing for functional polymorphisms of drug-metabolizing enzymes. Gene/drug pairs and barriers perceived in Spain

    PubMed Central

    Agúndez, José A. G.; Abad-Santos, Francisco; Aldea, Ana; Alonso-Navarro, Hortensia; Bernal, María L.; Borobia, Alberto M.; Borrás, Emma; Carballo, Miguel; Carvajal, Alfonso; García-Muñiz, José D.; Gervasini, Guillermo; Jiménez-Jiménez, Félix J.; Lucena, María I.; Martínez, Carmen; Sacristán, José A.; Salado, Inés; Sinués, Blanca; Vicente, Jorge; García-Martín, Elena

    2012-01-01

    The development of clinical practice recommendations or guidelines for the clinical use of biomarkers is an issue of great importance with regard to adverse drug reactions. The potential of pharmacogenomic biomarkers has been extensively investigated in recent years. However, several barriers to implementing the use of pharmacogenomics testing exist. We conducted a survey among members of the Spanish Societies of Pharmacology and Clinical Pharmacology to obtain information about the perception of such barriers and to compare the perceptions of participants about the relative importance of major gene/drug pairs. Of 11 potential barriers, the highest importance was attributed to lack of institutional support for pharmacogenomics testing, and to the issues related to the lack of guidelines. Of the proposed gene/drug pairs the highest importance was assigned to HLA-B/abacavir, UGT1A1/irinotecan, and CYP2D6/tamoxifen. In this perspective article, we compare the relative importance of 29 gene/drug pairs in the Spanish study with that of the same pairs in the American Society for Clinical Pharmacology and Therapeutics study, and we provide suggestions and areas of focus to develop a guide for clinical practice in pharmacogenomics testing. PMID:23233861

  10. Enzyme assays.

    PubMed

    Reymond, Jean-Louis; Fluxà, Viviana S; Maillard, Noélie

    2009-01-07

    Enzyme assays are analytical tools to visualize enzyme activities. In recent years a large variety of enzyme assays have been developed to assist the discovery and optimization of industrial enzymes, in particular for "white biotechnology" where selective enzymes are used with great success for economically viable, mild and environmentally benign production processes. The present article highlights the aspects of fluorogenic and chromogenic substrates, sensors, and enzyme fingerprinting, which are our particular areas of interest.

  11. Hepatitis A

    MedlinePlus

    ... inflammation of the liver.” This inflammation can be caused by a wide variety of toxins, drugs, and metabolic diseases, as well as infection. There are at least 5 hepatitis viruses. Hepatitis A is contracted when a child eats food or drinks water that is contaminated with the virus or has ...

  12. Hepatitis B

    MedlinePlus

    ... B to come back?Should I get the hepatitis B vaccine?What are the side effects of antiviral medicines?Will my liver ever be normal again? Last Updated: October 1996 This article ... B, hepatitis virus, Interferon alpha-2b, jaundice, Lamivudine, liver ...

  13. Possible drug–drug interaction in dogs and cats resulted from alteration in drug metabolism: A mini review

    PubMed Central

    Sasaki, Kazuaki; Shimoda, Minoru

    2015-01-01

    Pharmacokinetic drug–drug interactions (in particular at metabolism) may result in fatal adverse effects in some cases. This basic information, therefore, is needed for drug therapy even in veterinary medicine, as multidrug therapy is not rare in canines and felines. The aim of this review was focused on possible drug–drug interactions in dogs and cats. The interaction includes enzyme induction by phenobarbital, enzyme inhibition by ketoconazole and fluoroquinolones, and down-regulation of enzymes by dexamethasone. A final conclusion based upon the available literatures and author’s experience is given at the end of the review. PMID:26257936

  14. Case study 3. Application of basic enzyme kinetics to metabolism studies: real-life examples.

    PubMed

    Li, Yongmei; McCabe, Michelle; Podila, Lalitha; Tracy, Timothy S; Tweedie, Donald J

    2014-01-01

    An appreciation of the principles of enzyme kinetics can be applied in a number of drug metabolism applications. The concept for this chapter arose from a simple discussion on selecting appropriate time points to most efficiently assess metabolite profiles in a human Phase 1a clinical study (Subheading 4). By considering enzyme kinetics, a logical approach to the issue was derived. The dialog was an important learning opportunity for the participants in the discussion, and we have endeavored to capture this experience with other questions related to determination of K m and V max parameters, a consideration of the value of hepatocytes versus liver microsomes and enzyme inhibition parameters.

  15. Modulatory Effect of Taurine on 7,12-Dimethylbenz(a)Anthracene-Induced Alterations in Detoxification Enzyme System, Membrane Bound Enzymes, Glycoprotein Profile and Proliferative Cell Nuclear Antigen in Rat Breast Tissue.

    PubMed

    Vanitha, Manickam Kalappan; Baskaran, Kuppusamy; Periyasamy, Kuppusamy; Selvaraj, Sundaramoorthy; Ilakkia, Aruldoss; Saravanan, Dhiravidamani; Venkateswari, Ramachandran; Revathi Mani, Balasundaram; Anandakumar, Pandi; Sakthisekaran, Dhanapal

    2016-08-01

    The modulatory effect of taurine on 7,12-dimethylbenz(a)anthracene (DMBA)-induced breast cancer in rats was studied. DMBA (25 mg/kg body weight) was administered to induce breast cancer in rats. Protein carbonyl levels, activities of membrane bound enzymes (Na(+) /K(+) ATPase, Ca(2+) ATPase, and Mg(2+) ATPase), phase I drug metabolizing enzymes (cytochrome P450, cytochrome b5, NADPH cytochrome c reductase), phase II drug metabolizing enzymes (glutathione-S-transferase and UDP-glucuronyl transferase), glycoprotein levels, and proliferative cell nuclear antigen (PCNA) were studied. DMBA-induced breast tumor bearing rats showed abnormal alterations in the levels of protein carbonyls, activities of membrane bound enzymes, drug metabolizing enzymes, glycoprotein levels, and PCNA protein expression levels. Taurine treatment (100 mg/kg body weight) appreciably counteracted all the above changes induced by DMBA. Histological examination of breast tissue further supported our biochemical findings. The results of the present study clearly demonstrated the chemotherapeutic effect of taurine in DMBA-induced breast cancer.

  16. Pretreatment with turmeric modulates the inhibitory influence of cisplatin and paclitaxel on CYP2E1 and CYP3A1/2 in isolated rat hepatic microsomes.

    PubMed

    Ahmed, Enas M; EL-Maraghy, Shohda A; Teleb, Zakaria A; Shaheen, Amira A

    2014-09-05

    Previous animal studies have shown that turmeric can significantly modulate the activity of several drug metabolizing enzymes, this may dramatically affect the bioavailability of several drugs resulting in over dose or less therapeutic effects. This study was directed to evaluate the inhibitory effects of cisplatin and paclitaxel on two CYP450 enzymes namely CYP2E1 and CYP3A1/2 in hepatic microsomes isolated from normal and turmeric pretreated rats. Cisplatin and paclitaxel were added by different concentrations to hepatic microsomes isolated from untreated and turmeric (100 mg/kg/day) pretreated rats for 15 days after receiving pyrazole or dexamethasone for induction of CYP2E1 and CYP3A1/2 respectively. The kinetic potency of these drugs as CYP inhibitors was determined by analysis of Lineweaver-Burk plot. Addition of cisplatin or paclitaxel by (10, 50 and 100 μM) to hepatic microsomes from normal or turmeric pretreated rats caused a concentration dependent inhibition of CYP2E1, with an evidence of less inhibition in turmeric pretreated microsomes particularly at higher concentration. Both drugs at 100 μM displayed a mixed type of inhibition of CYP2E1 in normal or turmeric pretreated microsomes where paclitaxel was the most potent inhibitor. Cisplatin (10, 50 and 100 μM) caused a concentration dependant inhibition of CYP3A1/2 that was enhanced by turmeric pretreatment. The inhibition of CYP3A1/2 by cisplatin (100 μM) was in non-competitive manner with a smaller Ki value in turmeric pretreated microsomes. The inhibitory influence of paclitaxel (10, 50 and 100 μM) on CYP3A1/2 decreased with increasing the drug concentration and this inhibition was augmented by turmeric pretreatment. Interestingly, the inhibition of this enzyme by paclitaxel (10 μM) was switched from mixed type in normal microsomes to competitive manner in turmeric pretreated ones with a marked reduction of Ki values reflecting greater inhibitory influence of paclitaxel on CYP3A1/2 by turmeric

  17. Scrub typhus hepatitis confirmed by immunohistochemical staining.

    PubMed

    Chung, Jong-Hoon; Lim, Sung-Chul; Yun, Na-Ra; Shin, Sung-Heui; Kim, Choon-Mee; Kim, Dong-Min

    2012-09-28

    Scrub typhus is an acute febrile disease caused by Orientia tsutsugamushi (O. tsutsugamushi). We report herein the case of a woman who presented with fever and elevated serum levels of liver enzymes and who was definitively diagnosed with scrub typhus by histopathological examination of liver biopsy specimens, serological tests and nested polymerase chain reaction. Immunohistochemical staining using a monoclonal anti-O. tsutsugamushi antibody showed focally scattered positive immunoreactions in the cytoplasm of some hepatocytes. This case suggests that scrub typhus hepatitis causes mild focal inflammation due to direct liver damage without causing piecemeal necrosis or interface hepatitis. Thus, scrub typhus hepatitis differs from acute viral hepatitis secondary to liver damage due to host immune responses, which causes severe lobular disarray with diffuse hepatocytic degeneration, necrosis and apoptosis as well as findings indicative of hepatic cholestasis, such as hepatic bile plugs or brown pigmentation of hepatocytes.

  18. Part I---Evaluating Effects of Oligomer Formation on Cytochrome P450 2C9 Electron Transfer and Drug Metabolism, Part II---Utilizing Molecular Modeling Techniques to Study the Src-Interacting Proteins Actin Filament Associated Protein of 110 kDa (AFAP-110) and Cortactin

    NASA Astrophysics Data System (ADS)

    Jett, John Edward, Jr.

    The dissertation has been divided into two parts to accurately reflect the two distinct areas of interest pursued during my matriculation in the School of Pharmacy at West Virginia University. In Part I, I discuss research probing the nature of electron transfer in the Cytochrome P450 family of proteins, a group of proteins well-known for their role in drug metabolism. In Part II, I focus on in silico and in vitro work developed in concert to probe protein structure and protein-protein interactions involved in actin filament reorganization and cellular motility. Part I. Cytochrome P450s (P450s) are an important class of enzymes known to metabolize a variety of endogenous and xenobiotic compounds. P450s are most commonly found in liver and intestinal endothelial cells and are responsible for the metabolism of approximately 75% of pharmaceutical drugs on the market. CYP2C9---one of the six major P450 isoforms---is responsible for ˜20% of drug metabolism. Elucidation of the factors that affect in vitro drug metabolism is crucial to the accurate prediction of in vivo drug metabolism kinetics. Currently, the two major techniques for studying in vitro drug metabolism are solution-based. However, it is known that the results of solution-based studies can vary from in vivo drug metabolism. One reason suggested to account for this variation is the state of P450 oligomer formation in solution compared to the in vivo environment, where P450s are membrane-bound. To understand the details of how oligomer formation affects in vitro drug metabolism, it is imperative that techniques be developed which will allow for the unequivocal control of oligomer formation without altering other experimental parameters. Our long term goal of this research is to develop methods to more accurately predict in vivo drug metabolism from in vitro data. This section of the dissertation will discuss the development of a platform consisting of a doped silicon surface containing a large array of gold

  19. Eugenol-rich Fraction of Syzygium aromaticum (Clove) Reverses Biochemical and Histopathological Changes in Liver Cirrhosis and Inhibits Hepatic Cell Proliferation

    PubMed Central

    Ali, Shakir; Prasad, Ram; Mahmood, Amena; Routray, Indusmita; Shinkafi, Tijjani Salihu; Sahin, Kazim; Kucuk, Omer

    2014-01-01

    Background: Dried flower bud of Syzygium aromaticum (clove) is rich in eugenol, an antioxidant and antiinflammatory compound that can protect liver against injury. Clove, besides eugenol, also contains other pharmacologically active phytochemicals such as β-sitosterol and ascorbic acid. This study reports the effect of eugenol-rich fraction (ERF) of clove on liver cirrhosis induced by thioacetamide. Methods: Cirrhosis of the liver, which predisposes to hepatocellular carcinoma, was induced by administering thioacetamide (0.03%) in drinking water for 16 weeks. Cirrhotic animals were divided into two groups; the treated group was administered ERF for 9 weeks, one week after discontinuation of thioacetamide, while the other group received normal saline for a similar duration of time. Results: The treatment with ERF, as determined by histopathology and through a battery of biochemical markers of hepatic injury, oxidative stress and drug metabolizing enzymes, significantly ameliorated the signs of liver cirrhosis. It lowered the elevated levels of alkaline phosphatase, γ-glutamyl transferase and other biochemical changes in liver cirrhosis. Histopathology of the liver corroborated the effect of ERF with biochemical findings. ERF treatment further inhibited cell proliferation, as demonstrated by reduced [3H]-thymidine uptake. Conclusions: Data provide evidence supporting the protective action of ERF on liver cirrhosis. The study assumes significance because cirrhosis predisposes the liver to cancer, which is characterized by abnormal cell proliferation. ERF in this study is reported to inhibit hepatic cell proliferation and at the same time decrease oxidative stress, which might be the mechanism of protection against liver cirrhosis. PMID:25574464

  20. Hepatitis A

    MedlinePlus

    ... bowel movements Loss of appetite Low-grade fever Dark urine Joint pain Yellowing of the skin and ... person ingests even tiny amounts of contaminated fecal matter. The hepatitis A virus infects liver cells and ...

  1. Hepatic Encephalopathy

    MedlinePlus Videos and Cool Tools

    ... is a condition that causes temporary worsening of brain function in people with advanced liver disease. When ... travel through your body until they reach your brain, causing mental and physical symptoms of HE. Hepatic ...

  2. Hepatitis E

    MedlinePlus

    ... with a positive-sense, single-stranded ribonucleic acid (RNA) genome. The virus has at least 4 different ... RT-PCR) to detect the hepatitis E virus RNA in blood and/or stool; this assay requires ...

  3. Autoimmune hepatitis.

    PubMed

    Heneghan, Michael A; Yeoman, Andrew D; Verma, Sumita; Smith, Alastair D; Longhi, Maria Serena

    2013-10-26

    Autoimmune hepatitis is a disease of the hepatic parenchyma that can present in acute or chronic forms. In common with many autoimmune diseases, autoimmune hepatitis is associated with non-organ-specific antibodies in the context of hepatic autoimmunity. This dichotomy has made definition of a unifying hypothesis in the pathophysiology of the disease difficult, although data from the past 8 years have drawn attention to the role of regulatory T cells. Several triggers have been identified, and the disease arises in genetically susceptible individuals. Clinical and biochemical remission is achievable in up to 85% of cases. For the remaining patients, alternative immunosuppression strategies are an option. Liver transplantation provides an excellent outcome for patients with acute liver failure or complications of end-stage liver disease, including hepatocellular carcinoma. Variant or overlapping syndromes are worthy of consideration when unexpected disease features arise.

  4. Hepatitis E.

    PubMed

    Krawczynski, K; Aggarwal, R; Kamili, S

    2000-09-01

    Hepatitis E, previously known as enterically transmitted non-A, non-B hepatitis, is an infectious viral disease with clinical and morphologic features of acute hepatitis. Its causative agent, hepatitis E virus, consists of small, 32- to 34-nm diameter, icosahedral, nonenveloped particles with a single-stranded, positive-sense, 7.5-kb RNA. The virus has two main geographically distinct strains, Asian and Mexican; recently, novel isolates from nonendemic areas and a genetically related swine HEV have been described. HEV is responsible for large epidemics of acute hepatitis and a proportion of sporadic hepatitis cases in the Indian subcontinent, southeast and central Asia, the Middle East, parts of Africa, and Mexico. The virus is excreted in feces and is transmitted predominantly by fecal-oral route, usually through contaminated water. Person-to-person transmission is uncommon. Clinical attack rates are the highest among young adults. Recent evidence suggests that humans with subclinical HEV infection and animals may represent reservoirs of HEV; however, further data are needed. Diagnosis of hepatitis E is usually made by detection of specific IgM antibody, which disappears rapidly over a few months; IgG anti-HEV persists for