Sample records for xenobiotics including drugs

  1. Metabolic and redox barriers in the skin exposed to drugs and xenobiotics.

    PubMed

    Korkina, Liudmila

    2016-01-01

    Growing exposure of human skin to environmental and occupational hazards, to numerous skin care/beauty products, and to topical drugs led to a biomedical concern regarding sustainability of cutaneous chemical defence that is essential for protection against intoxication. Since skin is the largest extra-hepatic drug/xenobiotic metabolising organ where redox-dependent metabolic pathways prevail, in this review, publications on metabolic processes leading to redox imbalance (oxidative stress) and its autocrine/endocrine impact to cutaneous drug/xenobiotic metabolism were scrutinised. Chemical and photo-chemical skin barriers contain metabolic and redox compartments: their protective and homeostatic functions. The review will examine the striking similarity of adaptive responses to exogenous chemical/photo-chemical stressors and endogenous toxins in cutaneous metabolic and redox system; the role(s) of xenobiotics/drugs and phase II enzymes in the endogenous antioxidant defence and maintenance of redox balance; redox regulation of interactions between metabolic and inflammatory responses in skin cells; skin diseases sharing metabolic and redox problems (contact dermatitis, lupus erythematosus, and vitiligo) Due to exceptional the redox dependence of cutaneous metabolic pathways and interaction of redox active metabolites/exogenous antioxidants with drug/xenobiotic metabolism, metabolic tests of topical xenobiotics/drugs should be combined with appropriate redox analyses and performed on 3D human skin models.

  2. Xenobiotic-metabolizing enzymes in plants and their role in uptake and biotransformation of veterinary drugs in the environment.

    PubMed

    Bártíková, Hana; Skálová, Lenka; Stuchlíková, Lucie; Vokřál, Ivan; Vaněk, Tomáš; Podlipná, Radka

    2015-08-01

    Many various xenobiotics permanently enter plants and represent potential danger for their organism. For that reason, plants have evolved extremely sophisticated detoxification systems including a battery of xenobiotic-metabolizing enzymes. Some of them are similar to those in humans and animals, but there are several plant-specific ones. This review briefly introduces xenobiotic-metabolizing enzymes in plants and summarizes present information about their action toward veterinary drugs. Veterinary drugs are used worldwide to treat diseases and protect animal health. However, veterinary drugs are also unwantedly introduced into environment mostly via animal excrements, they persist in the environment for a long time and may impact on the non-target organisms. Plants are able to uptake, transform the veterinary drugs to non- or less-toxic compounds and store them in the vacuoles and cell walls. This ability may protect not only plant themselves but also other organisms, predominantly invertebrates and wild herbivores. The aim of this review is to emphasize the importance of plants in detoxification of veterinary drugs in the environment. The results of studies, which dealt with transport and biotransformation of veterinary drugs in plants, are summarized and evaluated. In conclusion, the risks and consequences of veterinary drugs in the environment and the possibilities of phytoremediation technologies are considered and future perspectives are outlined.

  3. Xenobiotic Metabolism and Gut Microbiomes

    PubMed Central

    Das, Anubhav; Srinivasan, Meenakshi; Ghosh, Tarini Shankar; Mande, Sharmila S.

    2016-01-01

    Humans are exposed to numerous xenobiotics, a majority of which are in the form of pharmaceuticals. Apart from human enzymes, recent studies have indicated the role of the gut bacterial community (microbiome) in metabolizing xenobiotics. However, little is known about the contribution of the plethora of gut microbiome in xenobiotic metabolism. The present study reports the results of analyses on xenobiotic metabolizing enzymes in various human gut microbiomes. A total of 397 available gut metagenomes from individuals of varying age groups from 8 nationalities were analyzed. Based on the diversities and abundances of the xenobiotic metabolizing enzymes, various bacterial taxa were classified into three groups, namely, least versatile, intermediately versatile and highly versatile xenobiotic metabolizers. Most interestingly, specific relationships were observed between the overall drug consumption profile and the abundance and diversity of the xenobiotic metabolizing repertoire in various geographies. The obtained differential abundance patterns of xenobiotic metabolizing enzymes and bacterial genera harboring them, suggest their links to pharmacokinetic variations among individuals. Additional analyses of a few well studied classes of drug modifying enzymes (DMEs) also indicate geographic as well as age specific trends. PMID:27695034

  4. Therapeutic and toxic blood concentrations of nearly 1,000 drugs and other xenobiotics

    PubMed Central

    2012-01-01

    Introduction In order to assess the significance of drug levels measured in intensive care medicine, clinical and forensic toxicology, as well as for therapeutic drug monitoring, it is essential that a comprehensive collection of data is readily available. Therefore, it makes sense to offer a carefully referenced compilation of therapeutic and toxic plasma concentration ranges, as well as half-lives, of a large number of drugs and other xenobiotics for quick and comprehensive information. Methods Data have been abstracted from original papers and text books, as well as from previous compilations, and have been completed with data collected in our own forensic and clinical toxicology laboratory. The data presented in the table and corresponding annotations have been developed over the past 20 years and longer. A previous compilation has been completely revised and updated. In addition, more than 170 substances, especially drugs that have been introduced to the market since 2003 as well as illegal drugs, which became known to cause intoxications, were added. All data were carefully referenced and more than 200 new references were included. Moreover, the annotations providing details were completely revised and more than 100 annotations were added. Results For nearly 1,000 drugs and other xenobiotics, therapeutic ("normal") and, if data were available, toxic and comatose-fatal blood-plasma concentrations and elimination half-lives were compiled in a table. Conclusions In case of intoxications, the concentration of the ingested substances and/or metabolites in blood plasma better predicts the clinical severity of the case when compared to the assumed amount and time of ingestion. Comparing and contrasting the clinical case against the data provided, including the half-life, may support the decision for or against further intensive care. In addition, the data provided are useful for the therapeutic monitoring of pharmacotherapies, to facilitate the diagnostic assessment

  5. Pregnane xenobiotic receptor in cancer pathogenesis and therapeutic response

    PubMed Central

    Pondugula, Satyanarayana R.; Mani, Sridhar

    2012-01-01

    Pregnane xenobiotic receptor (PXR) is an orphan nuclear receptor that regulates the metabolism of endobiotics and xenobiotics. PXR is promiscuous and unique in that it is activated by a diverse group of xenochemicals, including therapeutic anticancer drugs and naturally-occurring endocrine disruptors. PXR has been predominantly studied to understand its regulatory role in xenobiotic clearance in liver and intestine via induction of drug metabolizing enzymes and drug transporters. PXR, however, is widely expressed and has functional implications in other normal and malignant tissues, including breast, prostate, ovary, endometrium and bone. The differential expression of PXR and its target genes in cancer tissues has been suggested to determine the prognosis of chemotherapeutic outcome. In addition, the emerging evidence points to the implications of PXR in regulating apoptotic and antiapoptotic as well as growth factor signaling that promote tumor proliferation and metastasis. In this review, we highlight the recent progress made in understanding the role of PXR in cancer, discuss the future directions to further understand the mechanistic role of PXR in cancer, and conclude with the need to identify novel selective PXR modulators. PMID:22939994

  6. Xenobiotic metabolism in the fourth dimension: PARtners in time.

    PubMed

    Green, Carla B; Takahashi, Joseph S

    2006-07-01

    A significant portion of the transcriptome in mammals, including the PAR bZIP transcription factors DBP, HLF, and TEF, is under circadian clock control. In this issue of Cell Metabolism, Gachon and colleagues (Gachon et al., 2006) show that disruption of these three genes in mice alters gene expression patterns of many proteins involved in drug metabolism and in liver and kidney responses to xenobiotic agents. Triple mutant mice have severe physiological deficits, including increased hypersensitivity to xenobiotic agents and premature aging, highlighting the profound effect the circadian clock has on this important response system.

  7. Computer-aided prediction of xenobiotic metabolism in the human body

    NASA Astrophysics Data System (ADS)

    Bezhentsev, V. M.; Tarasova, O. A.; Dmitriev, A. V.; Rudik, A. V.; Lagunin, A. A.; Filimonov, D. A.; Poroikov, V. V.

    2016-08-01

    The review describes the major databases containing information about the metabolism of xenobiotics, including data on drug metabolism, metabolic enzymes, schemes of biotransformation and the structures of some substrates and metabolites. Computational approaches used to predict the interaction of xenobiotics with metabolic enzymes, prediction of metabolic sites in the molecule, generation of structures of potential metabolites for subsequent evaluation of their properties are considered. The advantages and limitations of various computational methods for metabolism prediction and the prospects for their applications to improve the safety and efficacy of new drugs are discussed. Bibliography — 165 references.

  8. Paternal nicotine exposure alters hepatic xenobiotic metabolism in offspring

    PubMed Central

    Vallaster, Markus P; Kukreja, Shweta; Bing, Xin Y; Ngolab, Jennifer; Zhao-Shea, Rubing; Gardner, Paul D; Tapper, Andrew R; Rando, Oliver J

    2017-01-01

    Paternal environmental conditions can influence phenotypes in future generations, but it is unclear whether offspring phenotypes represent specific responses to particular aspects of the paternal exposure history, or a generic response to paternal ‘quality of life’. Here, we establish a paternal effect model based on nicotine exposure in mice, enabling pharmacological interrogation of the specificity of the offspring response. Paternal exposure to nicotine prior to reproduction induced a broad protective response to multiple xenobiotics in male offspring. This effect manifested as increased survival following injection of toxic levels of either nicotine or cocaine, accompanied by hepatic upregulation of xenobiotic processing genes, and enhanced drug clearance. Surprisingly, this protective effect could also be induced by a nicotinic receptor antagonist, suggesting that xenobiotic exposure, rather than nicotinic receptor signaling, is responsible for programming offspring drug resistance. Thus, paternal drug exposure induces a protective phenotype in offspring by enhancing metabolic tolerance to xenobiotics. DOI: http://dx.doi.org/10.7554/eLife.24771.001 PMID:28196335

  9. Maternal drug abuse and human term placental xenobiotic and steroid metabolizing enzymes in vitro.

    PubMed

    Paakki, P; Stockmann, H; Kantola, M; Wagner, P; Lauper, U; Huch, R; Elovaara, E; Kirkinen, P; Pasanen, M

    2000-02-01

    We evaluated the impact of maternal drug abuse at term on human placental cytochrome P450 (CYP)-mediated (Phase I) xenobiotic and steroid-metabolizing activities [aromatase, 7-ethoxyresorufin O-deethylase (EROD), 7-ethoxycoumarin O-deethylase (ECOD), pyrene 1-hydroxylase (P1OH), and testosterone hydroxylase], and androstenedione-forming isomerase, NADPH quinone oxidoreductase (Phase II), UDP-glucuronosyltransferase (UGT), and glutathione S-transferase (GST) activities in vitro. Overall, the formation of androstenedione, P1OH, and testosterone hydroxylase was statistically significant between control and drug-abusing subjects; we observed no significant differences in any other of the phase I and II activities. In placentas from drug-abusing mothers, we found significant correlations between ECOD and P1OH activities (p < 0. 001), but not between ECOD and aromatase or P1OH and EROD activities; we also found significant correlations between blood cotinine and UGT activities (p < 0.01). In contrast, in controls (mothers who did not abuse drugs but did smoke cigarettes), the P1OH activity correlated with ECOD, EROD (p < 0.001), and testosterone hydroxylase (p < 0.001) activities. Our results (wider variation in ECOD activity among tissue from drug-abusing mothers and the significant correlation between P1OH and ECOD activities, but not with aromatase or EROD activities) indicate that maternal drug abuse results in an additive effect in enhancing placental xenobiotic metabolizing enzymes when the mother also smokes cigarettes; this may be due to enhancing a "silent" CYP form, or a new placental CYP form may be activated. The change in the steroid metabolism profile in vitro suggests that maternal drug abuse may alter normal hormonal homeostasis during pregnancy.

  10. Modulation of expression and activity of intestinal multidrug resistance-associated protein 2 by xenobiotics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tocchetti, Guillermo Nicolás

    The multidrug resistance-associated protein 2 (MRP2/ABCC2) is a transporter that belongs to the ATP-binding cassette (ABC) superfamily. In the intestine, it is localized to the apical membrane of the enterocyte and plays a key role in limiting the absorption of xenobiotics incorporated orally. MRP2 may also play a role in systemic clearance of xenobiotics available from the serosal side of the intestine. MRP2 transports a wide range of substrates, mainly organic anions conjugated with glucuronic acid, glutathione and sulfate and its expression can be modulated by xenobiotics at transcriptional- and post-transcriptional levels. Transcriptional regulation is usually mediated by a groupmore » of nuclear receptors. The pregnane X receptor (PXR) is a major member of this group. Relevant drugs described to up-regulate intestinal MRP2 via PXR are rifampicin, spironolactone and carbamazepine, among others. The constitutive androstane receptor (CAR, NR1I3) was also reported to modulate MRP2 expression, phenobarbital being a typical activator. Dietary compounds, including micronutrients and other natural products, are also capable of regulating intestinal MRP2 expression transcriptionally. We have given them particular attention since the composition of the food ingested daily is not necessarily supervised and may result in interactions with therapeutic drugs. Post-transcriptional regulation of MRP2 activity by xenobiotics, e.g. as a consequence of inhibitory actions, is also described in this review. Unfortunately, only few studies report on drug-drug or nutrient-drug interactions as a consequence of modulation of intestinal MRP2 activity by xenobiotics. Future clinical studies are expected to identify additional interactions resulting in changes in efficacy or safety of therapeutic drugs. - Highlights: • Intestinal MRP2 (ABCC2) expression and activity can be regulated by xenobiotics. • PXR and CAR are major MRP2 modulators through a transcriptional mechanism.

  11. Xenobiotics and the Glucocorticoid Receptor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gulliver, Linda S M, E-mail: linda.gulliver@otago.

    Glucocorticoid Receptor (GR) is present in virtually every human cell type. Representing a nuclear receptor superfamily, GR has several different isoforms essentially acting as ligand-dependent transcription factors, regulating glucocorticoid-responsive gene expression in both a positive and a negative manner. Although the natural ligand of the Glucocorticoid Receptor, glucocorticoids (GC) represent only some of the multiple ligands for GR. Xenobiotics, ubiquitous in the environment, bind to GR and are also capable of activating or repressing GR gene expression, thereby modulating GR cell and tissue-specific downstream effects in a multitude of ways that include responses to inflammatory, allergic, metabolic, neoplastic and autoimmunemore » processes. Many xenobiotics, if inadequately metabolized by xenobiotic metabolizing enzymes and not wholly eliminated, could have deleterious toxic effects with potentially lethal consequences. This review examines GR, the genomic and non-genomic actions of natural and synthetic GC and the body's handling of xenobiotic compounds, before reviewing what is presently known about GR's interactions with many of the more commonly encountered and some of the less well known GR-associated xenobiotics. GR promiscuity and crosstalk with other signaling pathways is discussed, alongside novel roles for GR that include mood disorder and addiction. A knowledge of GR interactions with xenobiotics is increasingly relevant when considering aging populations and the related prevalence of neoplastic disease, together with growing concerns around human exposure to mixtures of chemicals in the environment. Furthermore, escalating rates of obesity, Type 2 diabetes; autoimmune, allergy, addiction and mood disorder-related pathologies, require novel targeted interventions and GR appears a promising pharmacological candidate. - Highlights: • Biological impact of xenobiotics acting through Glucocorticoid Receptor. • Promiscuity of Glucocorticoid

  12. Retinoid-xenobiotic interactions: the Ying and the Yang

    PubMed Central

    2015-01-01

    The literature provides compelling evidence pointing to tight metabolic interactions between retinoids and xenobiotics. These are extensive and important for understanding xenobiotic actions in the body. Within the body, retinoids affect xenobiotic metabolism and actions and conversely, xenobiotics affect retinoid metabolism and actions. This article summarizes data that establish the importance of retinoid-dependent metabolic pathways for sustaining the body’s responses to xenobiotic exposure, including the roles of all-trans- and 9-cis-retinoic acid for protecting mammals from harmful xenobiotic effects and for ensuring xenobiotic elimination from the body. This review will also consider molecular mechanisms underlying xenobiotic toxicity focusing on how this may contribute to retinoid deficiency and disruption of normal retinoid homeostasis. Special attention is paid to xenobiotic molecular targets (nuclear receptors, regulatory proteins, enzymes, and transporters) which affect retinoid metabolism and signaling. PMID:26311625

  13. High-Fat Diets Alter the Modulatory Effects of Xenobiotics on Cytochrome P450 Activities

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sadler, Natalie C.; Webb-Robertson, Bobbie-Jo M.; Clauss, Therese R.

    Cytochrome P450 monooxygenases (P450) are key to the metabolism of myriad endogenous chemicals and xenobiotics, including the majority of therapeutic drugs. Dysregulated P450 activities can lead to altered drug metabolism and toxicity, oxidative stress, and inflammation; all physiological states frequently charged as the impetus for various chronic pathologies. We characterized the impact of common xenobiotic exposures, specifically high-fat diet and active or passive cigarette smoke, on the functional capacity of hepatic and pulmonary P450s. We employed an activity-based protein profiling approach to characterize the identity and activity level of measured individual P450 isoforms. Our results confirm expectations of significant alterationsmore » in pulmonary P450s due to cigarette smoke, but now reveal the repressive impact of high-fat diet-induced obesity on many hepatic P450s activities, and the dynamic alterations due to concomitant diet and smoke exposures on liver and lung P450 activities impacting drug metabolism and pathways of inflammation.« less

  14. The Therapeutic Role of Xenobiotic Nuclear Receptors against Metabolic Syndrome.

    PubMed

    Pu, Shuqi; Wu, Xiaojie; Yang, Xiaoying; Zhang, Yunzhan; Dai, Yunkai; Zhang, Yueling; Wu, Xiaoting; Liu, Yan; Cui, Xiaona; Jin, Haiyong; Cao, Jianhong; Li, Ruliu; Cai, Jiazhong; Cao, Qizhi; Hu, Ling; Gao, Yong

    2018-06-10

    Xenobiotic nuclear receptors (XNRs) are nuclear receptors that characterized by coordinately regulating the expression of genes encoding drug-metabolizing enzymes and transporters to essentially eliminate and detoxify xenobiotics and endobiotics from the body, including the peroxisome proliferator-activated receptor (PPAR), the farnesoid X receptor (FXR), the liver X receptor (LXR), the pregnane X receptor (PXR) and the constitutive androstane receptor (CAR). Heretofore, increasing evidences have suggested that these five XNRs are not only involved in the regulation of xeno-/endo-biotics detoxication but also the development of human diseases, such as cancer, obesity and diabetes. PPAR, FXR, LXR, PXR and CAR, as the receptors for numerous natural or synthetic compounds may be the most effective therapeutic targets in the treatment of metabolic diseases. In this review, we will focus on these five XNRs and their recently discovered functions in diabetes and its complications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  15. [Drug-drug interactions: interactions between xenobiotics].

    PubMed

    Haen, E

    2014-04-01

    Drug-drug interactions (DDI) are a major topic in programs for continuous medical education (CME). Many physicians are afraid of being trapped into charges of malpractice; however, DDI cannot be avoided in many cases. They belong to routine medical practice and it is often impossible to avoid them. Moreover, they do not just occur between drugs but between any kind of foreign substance (xenobiotica), such as food (e.g. grapefruit juice, broccoli, barbecue) as well as legal (e.g. tobacco smoke, caffeine and alcohol) and illegal drugs. Therefore, the medical challenge is not just to avoid any interaction. Instead the physician faces the question of how to proceed with drug treatment in the presence of such interactions. Based on the medical education a physician has to judge first of all whether there is a risk for interactions in the prescription being planned for an individual patient. The classification of interactions proposed in this article (PD1-PD4, PK1-PK3) might help as a sort of check list. For more detailed information the physician can then consult one of the many databases available on the internet, such as PSIAConline (http://www.psiac.de) and MediQ (http://www.mediq.ch). Pharmacokinetic interactions can be easily assessed, monitored and controlled by therapeutic drug monitoring (TDM). Besides these tools it is important to keep in mind that nobody knows everything; even physicians do not know everything. So take pride in asking someone who might help and for this purpose AGATE offers a drug information service AID (http://www.amuep-agate.de). Just good for nothing, without being based on any kind of medical approach are computer programs that judge prescriptions without taking into account a patient's individual peculiarities. In case these types of programs produce red exclamation marks or traffic lights to underline their judgment, they might even work in a contrapuntal way by just eliciting insecurity and fear.

  16. The Role of Xenobiotic-Metabolizing Enzymes in Anthelmintic Deactivation and Resistance in Helminths.

    PubMed

    Matoušková, Petra; Vokřál, Ivan; Lamka, Jiří; Skálová, Lenka

    2016-06-01

    Xenobiotic-metabolizing enzymes (XMEs) modulate the biological activity and behavior of many drugs, including anthelmintics. The effects of anthelmintics can often be abolished by XMEs when the drugs are metabolized to an inefficient compound. XMEs therefore play a significant role in anthelmintic efficacy. Moreover, differences in XMEs between helminths are reflected by differences in anthelmintic metabolism between target species. Taking advantage of the newly sequenced genomes of many helminth species, progress in this field has been remarkable. The present review collects up to date information regarding the most important XMEs (phase I and phase II biotransformation enzymes; efflux transporters) in helminths. The participation of these XMEs in anthelmintic metabolism and their possible roles in drug resistance are evaluated. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Structural insights into xenobiotic and inhibitor binding to human aldehyde oxidase.

    PubMed

    Coelho, Catarina; Foti, Alessandro; Hartmann, Tobias; Santos-Silva, Teresa; Leimkühler, Silke; Romão, Maria João

    2015-10-01

    Aldehyde oxidase (AOX) is a xanthine oxidase (XO)-related enzyme with emerging importance due to its role in the metabolism of drugs and xenobiotics. We report the first crystal structures of human AOX1, substrate free (2.6-Å resolution) and in complex with the substrate phthalazine and the inhibitor thioridazine (2.7-Å resolution). Analysis of the protein active site combined with steady-state kinetic studies highlight the unique features, including binding and substrate orientation at the active site, that characterize human AOX1 as an important drug-metabolizing enzyme. Structural analysis of the complex with the noncompetitive inhibitor thioridazine revealed a new, unexpected and fully occupied inhibitor-binding site that is structurally conserved among mammalian AOXs and XO. The new structural insights into the catalytic and inhibition mechanisms of human AOX that we now report will be of great value for the rational analysis of clinical drug interactions involving inhibition of AOX1 and for the prediction and design of AOX-stable putative drugs.

  18. Xenobiotics: Chapter 15

    USGS Publications Warehouse

    Bridges, Christine M.; Semlitsch, Raymond D.; Lannoo, Michael

    2005-01-01

    While a number of compounds have been reported as toxic to amphibians, until recently, there have been conspicuously few ecotoxicological studies concerning amphibians. Studies are now focusing on the effects of xenobiotics on amphibians, an interest likely stimulated by widespread reports of amphibian declines. It has been speculated that chemical contamination may be partially to blame for some documented amphibian declines, by disrupting growth, reproduction, and behavior. However, evidence that xenobiotics are directly to blame for population declines is sparse because environmental concentrations are typically not great enough to generate direct mortality. Although the effects of environmental contaminants on the amphibian immune system are currently unknown, it is possible that exposure to stressors such as organic pollutants (which enter ecosystems in the form of pesticides) may depress immune system function, thus allowing greater susceptibility to fungal infections. This chapter discusses toxicity testing for xenobiotics and presents the results of a study that has focused on the subtle effects of sublethal concentrations of the chemical carbaryl on tadpoles.

  19. Interactions among infections, nutrients and xenobiotics.

    PubMed

    Ilbäck, Nils-Gunnar; Friman, Göran

    2007-01-01

    During recent years there have been several incidents in which symptoms of disease have been linked to consumption of food contaminated by chemical substances (e.g., 2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD). Furthermore, outbreaks of infections in food-producing animals have attracted major attention regarding the safety of consumers, e.g., Bovine Spongiform Encephalitis (BSE) and influenza in chicken. As shown for several xenobiotics in an increasing number of experimental studies, even low-dose xenobiotic exposure may impair immune function over time, as well as microorganism virulence, resulting in more severe infectious diseases and associated complications. Moreover, during ongoing infection, xenobiotic uptake and distribution are often changed resulting in increased toxic insult to the host. The interactions among infectious agents, nutrients, and xenobiotics have thus become a developing concern and new avenue of research in food toxicology as well as in food-borne diseases. From a health perspective, in the risk assessment of xenobiotics in our food and environment, synergistic effects among microorganisms, nutrients, and xenobiotics will have to be considered. Otherwise, such effects may gradually change the disease panorama in society.

  20. PROXIMAL: a method for Prediction of Xenobiotic Metabolism.

    PubMed

    Yousofshahi, Mona; Manteiga, Sara; Wu, Charmian; Lee, Kyongbum; Hassoun, Soha

    2015-12-22

    Contamination of the environment with bioactive chemicals has emerged as a potential public health risk. These substances that may cause distress or disease in humans can be found in air, water and food supplies. An open question is whether these chemicals transform into potentially more active or toxic derivatives via xenobiotic metabolizing enzymes expressed in the body. We present a new prediction tool, which we call PROXIMAL (Prediction of Xenobiotic Metabolism) for identifying possible transformation products of xenobiotic chemicals in the liver. Using reaction data from DrugBank and KEGG, PROXIMAL builds look-up tables that catalog the sites and types of structural modifications performed by Phase I and Phase II enzymes. Given a compound of interest, PROXIMAL searches for substructures that match the sites cataloged in the look-up tables, applies the corresponding modifications to generate a panel of possible transformation products, and ranks the products based on the activity and abundance of the enzymes involved. PROXIMAL generates transformations that are specific for the chemical of interest by analyzing the chemical's substructures. We evaluate the accuracy of PROXIMAL's predictions through case studies on two environmental chemicals with suspected endocrine disrupting activity, bisphenol A (BPA) and 4-chlorobiphenyl (PCB3). Comparisons with published reports confirm 5 out of 7 and 17 out of 26 of the predicted derivatives for BPA and PCB3, respectively. We also compare biotransformation predictions generated by PROXIMAL with those generated by METEOR and Metaprint2D-react, two other prediction tools. PROXIMAL can predict transformations of chemicals that contain substructures recognizable by human liver enzymes. It also has the ability to rank the predicted metabolites based on the activity and abundance of enzymes involved in xenobiotic transformation.

  1. Estimation of maximum transdermal flux of nonionized xenobiotics from basic physicochemical determinants

    PubMed Central

    Milewski, Mikolaj; Stinchcomb, Audra L.

    2012-01-01

    An ability to estimate the maximum flux of a xenobiotic across skin is desirable both from the perspective of drug delivery and toxicology. While there is an abundance of mathematical models describing the estimation of drug permeability coefficients, there are relatively few that focus on the maximum flux. This article reports and evaluates a simple and easy-to-use predictive model for the estimation of maximum transdermal flux of xenobiotics based on three common molecular descriptors: logarithm of octanol-water partition coefficient, molecular weight and melting point. The use of all three can be justified on the theoretical basis of their influence on the solute aqueous solubility and the partitioning into the stratum corneum lipid domain. The model explains 81% of the variability in the permeation dataset comprised of 208 entries and can be used to obtain a quick estimate of maximum transdermal flux when experimental data is not readily available. PMID:22702370

  2. Applications of mass spectrometry in drug metabolism: 50 years of progress.

    PubMed

    Wen, Bo; Zhu, Mingshe

    2015-02-01

    Mass spectrometry plays a pivotal role in drug metabolism studies, which are an integral part of drug discovery and development nowadays. Metabolite identification has become critical to understanding the metabolic fate of drug candidates and to aid lead optimization with improved metabolic stability, toxicology and efficacy profiles. Ever since the introduction of atmospheric ionization techniques in the early 1990s, liquid chromatography coupled with mass spectrometry (LC/MS) has secured a central role as the predominant analytical platform for metabolite identification as LC and MS technologies continually advanced. In this review, we discuss the evolution of both MS technology and its applications over the past 50 years to meet the increasing demand of drug metabolism studies. These advances include ionization sources, mass analyzers, a wide range of MS acquisition strategies and data mining tools that have substantially accelerated the metabolite identification process and changed the overall drug metabolism landscape. Exemplary applications for characterization and identification of both small-molecule xenobiotics and biological macromolecules are described. In addition, this review discusses novel MS technologies and applications, including xenobiotic metabolomics that hold additional promise for advancing drug metabolism research, and offers thoughts on remaining challenges in studying the metabolism and disposition of drugs and other xenobiotics.

  3. 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...

  4. Differential Regulation of CYP3A4 and CYP3A5 and Its Implication in Drug Discovery

    PubMed Central

    Lolodi, Ogheneochukome; Wang, Yue-Ming; Wright, William C.; Chen, Taosheng

    2017-01-01

    Cancer cells use several mechanisms to resist the cytotoxic effects of drugs, resulting in tumor progression and invasion. One such mechanism capitalizes on the body’s natural defense against xenobiotics by increasing the rate of xenobiotic efflux and metabolic inactivation. Xenobiotic metabolism typically involves conversion of parent molecules to more soluble and easily excreted derivatives in reactions catalyzed by Phase I and Phase II drug metabolizing enzymes. Recent reports indicate that components of the xenobiotic response system are upregulated in some diseases, including many cancers. Such components include the pregnane X receptor (PXR) and the cytochrome P450 (CYP) 3A4 and 3A5 enzymes. The CYP3A enzymes are a subset of the numerous enzymes that are transcriptionally activated following the interaction of PXR and many ligands. Intense research is ongoing to understand the functional ramifications of aberrant expression of these components in diseased states with the goal of designing novel drugs that can selectively target them. PMID:28558634

  5. The microbial pharmacists within us: a metagenomic view of xenobiotic metabolism

    PubMed Central

    Spanogiannopoulos, Peter; Bess, Elizabeth N.; Carmody, Rachel N.; Turnbaugh, Peter J.

    2016-01-01

    Although the significance of human genetic polymorphisms in therapeutic outcomes is well established, the importance of our “second genome” (the microbiome) has been largely overlooked. In this Review, we highlight recent studies that shed light on the mechanisms linking the human gut microbiome to the efficacy and toxicity of xenobiotics, including drugs, dietary compounds and environmental toxins. Continued progress in this area could enable more precise tools for predicting patient responses and the development of a next generation of therapeutics based on or targeted at the gut microbiome. Indeed, the admirable goal of precision medicine may require us to first understand the microbial pharmacists within. PMID:26972811

  6. Targeting xenobiotic receptors PXR and CAR in human diseases

    PubMed Central

    Banerjee, Monimoy; Robbins, Delira; Chen, Taosheng

    2014-01-01

    Nuclear receptors such as the pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are xenobiotic receptors regulating not only drug metabolism and disposition but also various human diseases such as cancer, diabetes, inflammatory disease, metabolic disease and liver diseases, suggesting that PXR and CAR are promising targets for drug discovery. Consequently, there is an urgent need to discover and develop small molecules that target these PXR- and/or CAR-mediated human-disease-related pathways for relevant therapeutic applications. This review proposes approaches to target PXR and CAR, either individually or simultaneously, in the context of various human diseases, taking into consideration the structural differences between PXR and CAR. PMID:25463033

  7. [THE SYSTEM OF XENOBIOTICS BIOTRANSFORMATION OF HELMINTHS. RESEMBLANCE AND DIFFERENSES FROM SIMILAR HOST SYSTEMS (REWEW)].

    PubMed

    Smirnov, L P; Borvinskaya, E V; Suhovskaya, I V

    2016-01-01

    The three phases system xenobiotic biotransformation in cells as prokaryotes as eukaryotes was formed during the process of evolution. Clear and managed function of all three links of this system guarantee the survival of living organisms at alteration of chemical component of environment. Oxidation, reduction or hydrolysis of xenobiotics realize in phase I by insertion or opening reactive and hydrophilic groups in structure of drug molecule. In phase II xenobiotics or their metabolites from phase I conjugate with endogenic compounds, main of there are glutathione, glucuronic acid, amino acids and sulphates. Active transport of substrata, metabolites and conjugates through cell lipid membranes special transport proteins carry out (phase III). The system of xenobiotics biotransformation of helminths has essential differences from the same of vertebrate hosts. In particular, parasites do not reveal the activity of prime oxidases of phase I, such as CYP or FMO, in spite of the genes of these enzymes in DNA. As this phenomenon displays mainly in adult helminths, living in guts of vertebrates, then the hypothesis was formulated that this effect is related with adaptation to conditions of strong deficiency of oxygen, arise in a process of evolution (Kotze et al., 2006). Literature data testify the existence in helminths of unique forms of enzymes of phase II, the investigation of which present doubtless interest in relation with possible role in adaptation to parasitic mode of life. Notwithstanding that many of helminths GST in greater or lesser degree similar with enzymes of M, P, S and О classes of other organisms, nevertheless they have essential structural differences as compared with enzymes of hosts that makes perspective the search of specific anthelminthics vaccines. Transport of xenobiotics is now considered phase III of biotransformation. It was shown that proteins of this phase (ATP binding cassette transporters (ABC ) of parasites) play a key role in efflux

  8. Prevalence of xenobiotic substances in first-trimester blood samples from Danish pregnant women: a cross-sectional study.

    PubMed

    Aagaard, Sissel Kramer; Larsen, Agnete; Andreasen, Mette Findal; Lesnikova, Iana; Telving, Rasmus; Vestergaard, Anna Louise; Tørring, Niels; Uldbjerg, Niels; Bor, Pinar

    2018-03-03

    The aim of this study was to investigate the prevalence of xenobiotic substances, such as caffeine, nicotine and illicit drugs (eg, cannabis and cocaine), in blood samples from first-trimester Danish pregnant women unaware of the screening. A cross - sectional study examined 436 anonymised residual blood samples obtained during 2014 as part of the nationwide prenatal first-trimester screening programme. The samples were analysed by ultra performance liquid chromatography with high-resolution time-of-flight mass spectrometry. An antenatal clinic in a Danish city with 62 000 inhabitants, where >95% of pregnant women joined the screening programme. The prevalence and patterns of caffeine, nicotine, medication and illicit drug intake during the first trimester of pregnancy. The prevalence of prescription and over-the-counter drug detection was 17.9%, including acetaminophen (8.9%) and antidepressants (3.0%), of which citalopram (0.9%) was the most frequent. The prevalence of illegal drugs, indicators of smoking (nicotine/cotinine) and caffeine was 0.9%, 9.9%, and 76.4%, respectively. Only 17.4% of women had no substance identified in their sample. This study emphasises the need for further translational studies investigating lifestyle habits during pregnancy, as well as the underlying molecular mechanisms through which xenobiotic substances may affect placental function and fetal development. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  9. Generation Z: Adolescent Xenobiotic Abuse in the 21st Century.

    PubMed

    Eggleston, William; Stork, Christine

    2015-12-01

    NMDA receptor antagonists include the prescription medication ketamine, the illicit xenobiotics PCP, MXE, and other novel PCP analogs, and the OTC medication DXM. The NMDA receptor antagonist most commonly abused by adolescents in the United States is DXM. These xenobiotics cause dissociative effects by non-competitively inhibiting the action of glutamate at the NMDA receptor. Additionally, these agents modulate the actions of monoamine neurotransmitters, agonize opioid receptors, and inhibit nitric oxide synthase. Patients typically present with sympathomimetic and neuropsychiatric clinical manifestations after abuse of NMDA receptor antagonists. Treatment is generally symptomatic and supportive. Interventions include benzodiazepines, propofol, fluids, antiemetics, aggressive cooling, and respiratory support.

  10. Transcriptional regulation of xenobiotic detoxification in Drosophila

    PubMed Central

    Misra, Jyoti R.; Horner, Michael A.; Lam, Geanette; Thummel, Carl S.

    2011-01-01

    Living organisms, from bacteria to humans, display a coordinated transcriptional response to xenobiotic exposure, inducing enzymes and transporters that facilitate detoxification. Several transcription factors have been identified in vertebrates that contribute to this regulatory response. In contrast, little is known about this pathway in insects. Here we show that the Drosophila Nrf2 (NF-E2-related factor 2) ortholog CncC (cap ‘n’ collar isoform-C) is a central regulator of xenobiotic detoxification responses. A binding site for CncC and its heterodimer partner Maf (muscle aponeurosis fibromatosis) is sufficient and necessary for robust transcriptional responses to three xenobiotic compounds: phenobarbital (PB), chlorpromazine, and caffeine. Genetic manipulations that alter the levels of CncC or its negative regulator, Keap1 (Kelch-like ECH-associated protein 1), lead to predictable changes in xenobiotic-inducible gene expression. Transcriptional profiling studies reveal that more than half of the genes regulated by PB are also controlled by CncC. Consistent with these effects on detoxification gene expression, activation of the CncC/Keap1 pathway in Drosophila is sufficient to confer resistance to the lethal effects of the pesticide malathion. These studies establish a molecular mechanism for the regulation of xenobiotic detoxification in Drosophila and have implications for controlling insect populations and the spread of insect-borne human diseases. PMID:21896655

  11. Scavenging of free-radical metabolites of aniline xenobiotics and drugs by amino acid derivatives: toxicological implications of radical-transfer reactions.

    PubMed

    Michail, Karim; Baghdasarian, Argishti; Narwaley, Malyaj; Aljuhani, Naif; Siraki, Arno G

    2013-12-16

    We investigated a novel scavenging mechanism of arylamine free radicals by poly- and monoaminocarboxylates. Free radicals of arylamine xenobiotics and drugs did not react with oxygen in peroxidase-catalyzed reactions; however, they showed marked oxygen uptake in the presence of an aminocarboxylate. These free-radical intermediates were identified using the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and electron paramagnetic resonance (EPR) spectrometry. Diethylenetriaminepentaacetic acid (DTPA), a polyaminocarboxylate, caused a concentration-dependent attenuation of N-centered radicals produced by the peroxidative metabolism of arylamines with the subsequent formation of secondary aliphatic carbon-centered radicals stemming from the cosubstrate molecule. Analogously, N,N-dimethylglycine (DMG) and N-methyliminodiacetate (MIDA), but not iminodiacetic acid (IDA), demonstrated a similar scavenging effect of arylamine-derived free radicals in a horseradish peroxidase/H2O2 system. Using human promyelocytic leukemia (HL-60) cell lysate as a model of human neutrophils, DTPA, MIDA, and DMG readily reduced anilinium cation radicals derived from the arylamines and gave rise to the corresponding carbon radicals. The rate of peroxidase-triggered polymerization of aniline was studied as a measure of nitrogen-radical scavenging. Although, IDA had no effect on the rate of aniline polymerization, this was almost nullified in the presence of DTPA and MIDA at half of the molar concentration of the aniline substrate, whereas a 20 molar excess of DMPO caused only a partial inhibition. Furthermore, the yield of formaldehyde, a specific reaction endproduct of the oxidation of aminocarboxylates by aniline free-radical metabolites, was quantitatively determined. Azobenzene, a specific reaction product of peroxidase-catalyzed free-radical dimerization of aniline, was fully abrogated in the presence of DTPA, as confirmed by GC/MS. Under aerobic conditions, a radical-transfer reaction

  12. Vitreous humor analysis for the detection of xenobiotics in forensic toxicology: a review.

    PubMed

    Bévalot, Fabien; Cartiser, Nathalie; Bottinelli, Charline; Fanton, Laurent; Guitton, Jérôme

    2016-01-01

    Vitreous humor (VH) is a gelatinous substance contained in the posterior chamber of the eye, playing a mechanical role in the eyeball. It has been the subject of numerous studies in various forensic applications, primarily for the assessment of postmortem interval and for postmortem chemical analysis. Since most of the xenobiotics present in the bloodstream are detected in VH after crossing the selective blood-retinal barrier, VH is an alternative matrix useful for forensic toxicology. VH analysis offers particular advantages over other biological matrices: it is less prone to postmortem redistribution, is easy to collect, has relatively few interfering compounds for the analytical process, and shows sample stability over time after death. The present study is an overview of VH physiology, drug transport and elimination. Collection, storage, analytical techniques and interpretation of results from qualitative and quantitative points of view are dealt with. The distribution of xenobiotics in VH samples is thus discussed and illustrated by a table reporting the concentrations of 106 drugs from more than 300 case reports. For this purpose, a survey was conducted of publications found in the MEDLINE database from 1969 through April 30, 2015.

  13. Xenobiotic metabolizing enzyme (XME) expression in aging humans.

    EPA Science Inventory

    In the presence of foreign compounds, metabolic homeostasis of the organism is maintained by the liver’s ability to detoxify and eliminate these xenobiotics. This is accomplished, in part, by the expression of XMEs, which metabolize xenobiotics and determine whether exposure will...

  14. Xenobiotic-metabolizing enzymes in Bacillus anthracis: molecular and functional analysis of a truncated arylamine N-acetyltransferase isozyme.

    PubMed

    Kubiak, Xavier; Duval, Romain; Pluvinage, Benjamin; Chaffotte, Alain F; Dupret, Jean-Marie; Rodrigues-Lima, Fernando

    2017-07-01

    The arylamine N-acetyltransferases (NATs) are xenobiotic-metabolizing enzymes that play an important role in the detoxification and/or bioactivation of arylamine drugs and xenobiotics. In bacteria, NATs may contribute to the resistance against antibiotics such as isoniazid or sulfamides through their acetylation, which makes this enzyme family a possible drug target. Bacillus anthracis, a bacterial species of clinical significance, expresses three NAT isozymes with distinct structural and enzymatic properties, including an inactive isozyme ((BACAN)NAT3). (BACAN)NAT3 features both a non-canonical Glu residue in its catalytic triad and a truncated C-terminus domain. However, the role these unusual characteristics play in the lack of activity of the (BACAN)NAT3 isozyme remains unclear. Protein engineering, recombinant expression, enzymatic analyses with aromatic amine substrates and phylogenetic analysis approaches were conducted. The deletion of guanine 580 (G580) in the nat3 gene was shown to be responsible for the expression of a truncated (BACAN)NAT3 isozyme. Artificial re-introduction of G580 in the nat3 gene led to a functional enzyme able to acetylate several arylamine drugs displaying structural characteristics comparable with its functional Bacillus cereus homologue ((BACCR)NAT3). Phylogenetic analysis of the nat3 gene in the B. cereus group further indicated that nat3 may constitute a pseudogene of the B. anthracis species. The existence of NATs with distinct properties and evolution in Bacillus species may account for their adaptation to their diverse chemical environments. A better understanding of these isozymes is of importance for their possible use as drug targets. This article is part of a themed section on Drug Metabolism and Antibiotic Resistance in Micro-organisms. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.14/issuetoc. © 2016 The British Pharmacological Society.

  15. A Global Genomic and Genetic Strategy to Predict Pathway Activation of Xenobiotic Responsive Transcription Factors in the Mouse Liver

    EPA Science Inventory

    Many drugs and environmentally-relevant chemicals activate xenobiotic-responsive transcription factors(TF). Identification of target genes of these factors would be useful in predicting pathway activation in in vitro chemical screening. Starting with a large compendium of Affymet...

  16. Humanized mouse lines and their application for prediction of human drug metabolism and toxicological risk assessment

    PubMed Central

    Cheung, Connie; Gonzalez, Frank J

    2008-01-01

    Cytochrome P450s (P450s) are important enzymes involved in the metabolism of xenobiotics, particularly clinically used drugs, and are also responsible for metabolic activation of chemical carcinogens and toxins. Many xenobiotics can activate nuclear receptors that in turn induce the expression of genes encoding xenobiotic metabolizing enzymes and drug transporters. Marked species differences in the expression and regulation of cytochromes P450 and xenobiotic nuclear receptors exist. Thus obtaining reliable rodent models to accurately reflect human drug and carcinogen metabolism is severely limited. Humanized transgenic mice were developed in an effort to create more reliable in vivo systems to study and predict human responses to xenobiotics. Human P450s or human xenobiotic-activated nuclear receptors were introduced directly or replaced the corresponding mouse gene, thus creating “humanized” transgenic mice. Mice expressing human CYP1A1/CYP1A2, CYP2E1, CYP2D6, CYP3A4, CY3A7, PXR, PPARα were generated and characterized. These humanized mouse models offers a broad utility in the evaluation and prediction of toxicological risk that may aid in the development of safer drugs. PMID:18682571

  17. 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

  18. Characterization of the Impact of Life Stage on Xenobiotic Metabolizing Enzyme Expression and Gene -Chemical Interactions in the Liver

    EPA Science Inventory

    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). We have carried out a comprehensive analysis of the mRNA expression of XMETs thro...

  19. Xenobiotic Transporter Expression along the Male Genital Tract1

    PubMed Central

    Klein, David M.; Wright, Stephen H.; Cherrington, Nathan J.

    2015-01-01

    The male genital tract plays an important role in protecting sperm by forming a distinct compartment separate from the body which limits exposure to potentially toxic substrates. Transporters along this tract can influence the distribution of xenobiotics into the male genital tract through efflux back into the blood or facilitating the accumulation of toxicants. The aim of this study was to quantitatively determine the constitutive mRNA expression of 30 xenobiotic transporters in caput and cauda regions of the epididymis, vas deferens, prostate, and seminal vesicles from adult Sprague-Dawley rats. The epididymis was found to express at least moderate levels of 18 transporters, vas deferens 15, seminal vesicles 23, and prostate 18. Constitutive expression of these xenobiotic transporters in the male genital tract may provide insight into the xenobiotics that can potentially be transported into these tissues and may provide the molecular mechanism for site specific toxicity of select agents. PMID:24814985

  20. Current knowledge of detoxification mechanisms of xenobiotic in honey bees.

    PubMed

    Gong, Youhui; Diao, Qingyun

    2017-01-01

    The western honey bee Apis mellifera is the most important managed pollinator species in the world. Multiple factors have been implicated as potential causes or factors contributing to colony collapse disorder, including honey bee pathogens and nutritional deficiencies as well as exposure to pesticides. Honey bees' genome is characterized by a paucity of genes associated with detoxification, which makes them vulnerable to specific pesticides, especially to combinations of pesticides in real field environments. Many studies have investigated the mechanisms involved in detoxification of xenobiotics/pesticides in honey bees, from primal enzyme assays or toxicity bioassays to characterization of transcript gene expression and protein expression in response to xenobiotics/insecticides by using a global transcriptomic or proteomic approach, and even to functional characterizations. The global transcriptomic and proteomic approach allowed us to learn that detoxification mechanisms in honey bees involve multiple genes and pathways along with changes in energy metabolism and cellular stress response. P450 genes, is highly implicated in the direct detoxification of xenobiotics/insecticides in honey bees and their expression can be regulated by honey/pollen constitutes, resulting in the tolerance of honey bees to other xenobiotics or insecticides. P450s is also a key detoxification enzyme that mediate synergism interaction between acaricides/insecticides and fungicides through inhibition P450 activity by fungicides or competition for detoxification enzymes between acaricides. With the wide use of insecticides in agriculture, understanding the detoxification mechanism of insecticides in honey bees and how honeybees fight with the xenobiotis or insecticides to survive in the changing environment will finally benefit honeybees' management.

  1. Genomic analysis of the aging rodent and human liver: impact on xenobiotic metabolism

    EPA Science Inventory

    Metabolic homeostasis of the organism is maintained by the liver’s ability to detoxify and eliminate xenobiotics. This is accomplished, in part, by xenobiotic metabolizing enzymes (XMEs), which metabolize xenobiotics and determine whether exposure will result in toxicity. Some ev...

  2. Effects of Brown Rice and White Rice on Expression of Xenobiotic Metabolism Genes in Type 2 Diabetic Rats

    PubMed Central

    Imam, Mustapha Umar; Ismail, Maznah

    2012-01-01

    Xenobiotics constantly influence biological systems through several means of interaction. These interactions are disturbed in type 2 diabetes, with implications for disease outcome. We aimed to study the implications of such disturbances on type 2 diabetes and rice consumption, the results of which could affect management of the disease in developing countries. In a type 2 diabetic rat model induced through a combination of high fat diet and low dose streptozotocin injection, up-regulation of xenobiotic metabolism genes in the diabetic untreated group was observed. Xenobiotic metabolism genes were upregulated more in the white rice (WR) group than the diabetic untreated group while the brown rice (BR) group showed significantly lower expression values, though not as effective as metformin, which gave values closer to the normal non-diabetic group. The fold changes in expression in the WR group compared to the BR group for Cyp2D4, Cyp3A1, Cyp4A1, Cyp2B1, Cyp2E1, Cyp2C11, UGT2B1, ALDH1A1 and Cyp2C6 were 2.6, 2, 1.5, 4, 2.8, 1.5, 1.8, 3 and 5, respectively. Our results suggest that WR may upregulate these genes in type 2 diabetes more than BR, potentially causing faster drug metabolism, less drug efficacy and more toxicity. These results may have profound implications for rice eating populations, constituting half the world’s population. PMID:22942722

  3. Xenobiotics removal by adsorption in the context of tertiary treatment: a mini review.

    PubMed

    Tahar, Alexandre; Choubert, Jean-Marc; Coquery, Marina

    2013-08-01

    Many xenobiotics, including several pharmaceuticals and pesticides, are poorly treated in domestic wastewater treatment plants. Adsorption processes, such as with activated carbons, could be a solution to curb their discharge into the aquatic environment. As adsorbent-like activated carbon is known to be expensive, identifying promising alternative adsorbent materials is a key challenge for efficient yet affordable xenobiotic removal from wastewaters. As part of the effort to address this challenge, we surveyed the literature on pharmaceutical and pesticide xenobiotics and built a database compiling data from 38 scientific publications covering 65 xenobiotics and 58 materials. Special focus was given to the relevance and comparability of the data to the characteristics of the adsorbent materials used and to the operating conditions of the batch tests inventoried. This paper gives an in-depth overview of the adsorption capacities of various adsorbents. The little data on alternative adsorbent materials, especially for the adsorption of pharmaceuticals, makes it difficult to single out any one activated carbon alternative capable of adsorbing pesticides and pharmaceuticals at the tertiary stage of treatment. There is a pressing need for further lab-scale experiments to investigate the tertiary treatment of discharged effluents. We conclude with recommendations on how future data should best be used and interpreted.

  4. 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. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

  5. Human extrahepatic cytochromes P450: function in xenobiotic metabolism and tissue-selective chemical toxicity in the respiratory and gastrointestinal tracts.

    PubMed

    Ding, Xinxin; Kaminsky, Laurence S

    2003-01-01

    Cytochrome P450 (CYP) enzymes in extrahepatic tissues often play a dominant role in target tissue metabolic activation of xenobiotic compounds. They may also determine drug efficacy and influence the tissue burden of foreign chemicals or bioavailability of therapeutic agents. This review focuses on xenobiotic-metabolizing CYPs of the human respiratory and gastrointestinal tracts, including the lung, trachea, nasal respiratory and olfactory mucosa, esophagus, stomach, small intestine, and colon. Many CYPs are expressed in one or more of these organs, including CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2A13, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP2F1, CYP2J2, CYP2S1, CYP3A4, CYP3A5, and CYP4B1. Of particular interest are the preferential expression of certain CYPs in the respiratory tract and the regional differences in CYP expression profile in different parts of the gastrointestinal tract. Current research activities on the characterization of CYP expression, function, and regulation in these tissues, as well as future research needs, are discussed.

  6. INTERINDIVIDUAL VARIANCE OF CYTOCHROME P450 FORMS IN HUMAN HEPATIC MICROSOMES: CORRELATION OF INDIVIDUAL FORMS WITH XENOBIOTIC METABOLISM AND IMPLICATIONS IN RISK ASSESSMENT

    EPA Science Inventory

    Differences in biotransformation activities may alter the bioavailability or efficacy of drugs, provide protection from certain xenobiotic and environmental agents, or increase toxicity of others. Cytochrome P450 (CYP450) enzymes are responsible for the majority of oxidation reac...

  7. Biology of PXR: role in drug-hormone interactions

    PubMed Central

    Wang, Jing; Dai, Shu; Guo, Yan; Xie, Wen; Zhai, Yonggong

    2014-01-01

    Hormonal homeostasis is essential for a variety of physiological and pathological processes. Elimination and detoxification of xenobiotics, such as drugs introduced into the human body, could disrupt the balance of hormones due to the induction of drug metabolizing enzymes (DMEs) and transporters. Pregnane X receptor (PXR, NR1I2) functions as a master xenobiotic receptor involved in drug metabolism and drug-drug interactions by its coordinated transcriptional regulation of phase I and phase II DMEs and transporters. Recently, increasing evidences indicate that PXR can also mediate the endocrine disruptor function and thus impact the integrity of the endocrine system. This review focuses primarily on the recent advances in our understanding of the function of PXR in glucocorticoid, mineralocorticoid, androgen and estrogen homeostasis. The elucidation of PXR-mediated drug-hormone interactions might have important therapeutic implications in dealing with hormone-dependent diseases and safety assessment of drugs. PMID:26417296

  8. Spatio-temporal Model of Xenobiotic Distribution and Metabolism in an in Silico Mouse Liver Lobule

    NASA Astrophysics Data System (ADS)

    Fu, Xiao; Sluka, James; Clendenon, Sherry; Glazier, James; Ryan, Jennifer; Dunn, Kenneth; Wang, Zemin; Klaunig, James

    Our study aims to construct a structurally plausible in silico model of a mouse liver lobule to simulate the transport of xenobiotics and the production of their metabolites. We use a physiologically-based model to calculate blood-flow rates in a network of mouse liver sinusoids and simulate transport, uptake and biotransformation of xenobiotics within the in silico lobule. Using our base model, we then explore the effects of variations of compound-specific (diffusion, transport and metabolism) and compound-independent (temporal alteration of blood flow pattern) parameters, and examine their influence on the distribution of xenobiotics and metabolites. Our simulations show that the transport mechanism (diffusive and transporter-mediated) of xenobiotics and blood flow both impact the regional distribution of xenobiotics in a mouse hepatic lobule. Furthermore, differential expression of metabolic enzymes along each sinusoid's portal to central axis, together with differential cellular availability of xenobiotics, induce non-uniform production of metabolites. Thus, the heterogeneity of the biochemical and biophysical properties of xenobiotics, along with the complexity of blood flow, result in different exposures to xenobiotics for hepatocytes at different lobular locations. We acknowledge support from National Institute of Health GM 077138 and GM 111243.

  9. 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

  10. Systems approaches evaluating the perturbation of xenobiotic metabolism in response to cigarette smoke exposure in nasal and bronchial tissues.

    PubMed

    Iskandar, Anita R; Martin, Florian; Talikka, Marja; Schlage, Walter K; Kostadinova, Radina; Mathis, Carole; Hoeng, Julia; Peitsch, Manuel C

    2013-01-01

    Capturing the effects of exposure in a specific target organ is a major challenge in risk assessment. Exposure to cigarette smoke (CS) implicates the field of tissue injury in the lung as well as nasal and airway epithelia. Xenobiotic metabolism in particular becomes an attractive tool for chemical risk assessment because of its responsiveness against toxic compounds, including those present in CS. This study describes an efficient integration from transcriptomic data to quantitative measures, which reflect the responses against xenobiotics that are captured in a biological network model. We show here that our novel systems approach can quantify the perturbation in the network model of xenobiotic metabolism. We further show that this approach efficiently compares the perturbation upon CS exposure in bronchial and nasal epithelial cells in vivo samples obtained from smokers. Our observation suggests the xenobiotic responses in the bronchial and nasal epithelial cells of smokers were similar to those observed in their respective organotypic models exposed to CS. Furthermore, the results suggest that nasal tissue is a reliable surrogate to measure xenobiotic responses in bronchial tissue.

  11. Systems Approaches Evaluating the Perturbation of Xenobiotic Metabolism in Response to Cigarette Smoke Exposure in Nasal and Bronchial Tissues

    PubMed Central

    Iskandar, Anita R.; Martin, Florian; Talikka, Marja; Schlage, Walter K.; Mathis, Carole; Hoeng, Julia; Peitsch, Manuel C.

    2013-01-01

    Capturing the effects of exposure in a specific target organ is a major challenge in risk assessment. Exposure to cigarette smoke (CS) implicates the field of tissue injury in the lung as well as nasal and airway epithelia. Xenobiotic metabolism in particular becomes an attractive tool for chemical risk assessment because of its responsiveness against toxic compounds, including those present in CS. This study describes an efficient integration from transcriptomic data to quantitative measures, which reflect the responses against xenobiotics that are captured in a biological network model. We show here that our novel systems approach can quantify the perturbation in the network model of xenobiotic metabolism. We further show that this approach efficiently compares the perturbation upon CS exposure in bronchial and nasal epithelial cells in vivo samples obtained from smokers. Our observation suggests the xenobiotic responses in the bronchial and nasal epithelial cells of smokers were similar to those observed in their respective organotypic models exposed to CS. Furthermore, the results suggest that nasal tissue is a reliable surrogate to measure xenobiotic responses in bronchial tissue. PMID:24224167

  12. DrugBank 4.0: shedding new light on drug metabolism.

    PubMed

    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.

  13. Back to the future: transgenerational transmission of xenobiotic-induced epigenetic remodeling

    PubMed Central

    Jiménez-Chillarón, Josep C; Nijland, Mark J; Ascensão, António A; Sardão, Vilma A; Magalhães, José; Hitchler, Michael J; Domann, Frederick E; Oliveira, Paulo J

    2015-01-01

    Epigenetics, or regulation of gene expression independent of DNA sequence, is the missing link between genotype and phenotype. Epigenetic memory, mediated by histone and DNA modifications, is controlled by a set of specialized enzymes, metabolite availability, and signaling pathways. A mostly unstudied subject is how sub-toxic exposure to several xenobiotics during specific developmental stages can alter the epigenome and contribute to the development of disease phenotypes later in life. Furthermore, it has been shown that exposure to low-dose xenobiotics can also result in further epigenetic remodeling in the germ line and contribute to increase disease risk in the next generation (multigenerational and transgenerational effects). We here offer a perspective on current but still incomplete knowledge of xenobiotic-induced epigenetic alterations, and their possible transgenerational transmission. We also propose several molecular mechanisms by which the epigenetic landscape may be altered by environmental xenobiotics and hypothesize how diet and physical activity may counteract epigenetic alterations. PMID:25774863

  14. Influence of multidrug resistance and drug transport proteins on chemotherapy drug metabolism.

    PubMed

    Joyce, Helena; McCann, Andrew; Clynes, Martin; Larkin, Annemarie

    2015-05-01

    Chemotherapy involving the use of anticancer drugs remains an important strategy in the overall management of patients with metastatic cancer. Acquisition of multidrug resistance remains a major impediment to successful chemotherapy. Drug transporters in cell membranes and intracellular drug metabolizing enzymes contribute to the resistance phenotype and determine the pharmacokinetics of anticancer drugs in the body. ATP-binding cassette (ABC) transporters mediate the transport of endogenous metabolites and xenobiotics including cytotoxic drugs out of cells. Solute carrier (SLC) transporters mediate the influx of cytotoxic drugs into cells. This review focuses on the substrate interaction of these transporters, on their biology and what role they play together with drug metabolizing enzymes in eliminating therapeutic drugs from cells. The majority of anticancer drugs are substrates for the ABC transporter and SLC transporter families. Together, these proteins have the ability to control the influx and the efflux of structurally unrelated chemotherapeutic drugs, thereby modulating the intracellular drug concentration. These interactions have important clinical implications for chemotherapy because ultimately they determine therapeutic efficacy, disease progression/relapse and the success or failure of patient treatment.

  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. Regulation of hepatic ABCC transporters by xenobiotics and in disease states

    PubMed Central

    Gu, Xinsheng; Manautou, Jose E.

    2015-01-01

    The subfamily of ABCC transporters consists of 13 members in mammals, including the multidrug resistance-associated proteins (MRPs), sulfonylurea receptors (SURs), and the cystic fibrosis transmembrane conductance regulator (CFTR). These proteins play roles in chemical detoxification, disposition, and normal cell physiology. ABCC transporters are expressed differentially in the liver and are regulated at the transcription and translation level. Their expression and function are also controlled by post-translational modification and membrane-trafficking events. These processes are tightly regulated. Information about alterations in the expression of hepatobiliary ABCC transporters could provide important insights into the pathogenesis of diseases and disposition of xenobiotics. In this review, we describe the regulation of hepatic ABCC transporters in humans and rodents by a variety of xenobiotics, under disease states and in genetically modified animal models deficient in transcription factors, transporters, and cell-signaling molecules. PMID:20233023

  17. It’s War Out There: Fighting for life with xenobiotic degrading enzymes

    USDA-ARS?s Scientific Manuscript database

    It’s War Out There: Fighting for life with xenobiotic degrading enzymes Beta-lactamase enzymes are well studied because of their tremendous impact on medicine. Their prominent role is in resistance to beta-lactam (four membered lactam ring) antibiotics including the first and most famous fungally d...

  18. DrugMetZ DB: an anthology of human drug metabolizing Chytochrome P450 enzymes.

    PubMed

    Antony, Tresa Remya Thomas; Nagarajan, Shanthi

    2006-11-14

    Understandings the basics of Cytochrome P450 (P450 or CYP) will help to discern drug metabolism. CYP, a super-family of heme-thiolate proteins, are found in almost all living organisms and is involved in the biotransformation of a diverse range of xenobiotics, therapeutic drugs and toxins. Here, we describe DrugMetZ DB, a database for CYP metabolizing drugs. The DB is implemented in MySQL, PHP and HTML. www.bicpu.edu.in/DrugMetZDB/

  19. Cytotoxic effects and aromatase inhibition by xenobiotic endocrine disrupters alone and in combination.

    PubMed

    Benachour, Nora; Moslemi, Safa; Sipahutar, Herbert; Seralini, Gilles-Eric

    2007-07-15

    Xenobiotics may cause long-term adverse effects in humans, especially at the embryonic level, raising questions about their levels of exposure, combined effects, and crucial endpoints. We are interested in the possible interactions between xenobiotic endocrine disrupters, cellular viability and androgen metabolism. Accordingly, we tested aroclor 1254 (A1254), atrazine (AZ), o,p'-DDT, vinclozolin (VZ), p,p'-DDE, bisphenol A (BPA), chlordecone (CD), nonylphenol (NP), tributylin oxide (TBTO), and diethylstilbestrol (DES) for cellular toxicity against human embryonic 293 cells, and activity against cellular aromatase, but also on placental microsomes and on the purified equine enzyme. Cellular viability was affected in 24 h by all the xenobiotics with a threshold at 50 microM (except for TBTO and DES, 10 microM threshold), and aromatase was inhibited at non-toxic doses. In combination synergism was observed reducing the threshold values of toxicity to 4-10 microM, and aromatase activity by 50% in some cases. In placental microsomes the most active xenobiotics rapidly inhibited microsomal aromatase in a manner independent of NADPH metabolism. Prolonged exposures to low doses in cells generally amplified by 50 times aromatase inhibition. These xenobiotics may act by inhibition of the active site or by allosteric effects on the enzyme. Bioaccumulation is a feature of some xenobiotics, especially chlordecone, DDT and DDE, and low level chronic exposures can also affect cell signaling mechanisms. This new information about the mechanism of action of these xenobiotics will assist in improved molecular design with a view to providing safer compounds for use in the (human) environment.

  20. Multiple resistance to carcinogens and xenobiotics: P-glycoproteins as universal detoxifiers.

    PubMed

    Efferth, Thomas; Volm, Manfred

    2017-07-01

    The detoxification of toxic substances is of general relevance in all biological systems. The plethora of exogenous xenobiotic compounds and endogenous toxic metabolic products explains the evolutionary pressure of all organisms to develop molecular mechanisms to detoxify and excrete harmful substances from the body. P-glycoprotein and other members of the ATP-binding cassette (ABC) transporter family extrude innumerous chemical compounds out of cells. Their specific expression in diverse biological contexts cause different phenotypes: (1) multidrug resistance (MDR) and thus failure of cancer chemotherapy, (2) avoidance of accumulation of carcinogens and prevention of carcinogenesis in healthy tissues, (3) absorption, distribution, metabolization and excretion (ADME) of pharmacological drugs in human patients, (4) protection from environmental toxins in aquatic organisms (multi-xenobiotic resistance, MXR). Hence ABC-transporters may have opposing effects for organismic health reaching from harmful in MDR of tumors to beneficial for maintenance of health in MXR. While their inhibition by specific inhibitors may improve treatment success in oncology and avoid carcinogenesis, blocking of ABC-transporter-driven efflux by environmental pollutants leads to ecotoxicological consequences in marine biotopes. Poisoned seafood may enter the food-chain and cause intoxications in human beings. As exemplified with ABC-transporters, joining forces in interdisciplinary research may, therefore, be a wise strategy to fight problems in human medicine and environmental sciences.

  1. Coordinated Changes in Xenobiotic Metabolizing Enzyme Gene Expression in Aging Male Rats

    EPA Science Inventory

    In order to gain better insight on aging and susceptibility, we characterized the expression of xenobiotic metabolizing enzymes (XMEs) from the livers of rats to evaluate the change in capacity to respond to xenobiotics across the adult lifespan. Gene expression profiles for XMEs...

  2. 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

  3. The biochemistry and molecular biology of xenobiotic polymer degradation by microorganisms.

    PubMed

    Kawai, Fusako

    2010-01-01

    Research on microbial degradation of xenobiotic polymers has been underway for more than 40 years. It has exploited a new field not only in applied microbiology but also in environmental microbiology, and has greatly contributed to polymer science by initiating the design of biodegradable polymers. Owing to the development of analytical tools and technology, molecular biological and biochemical advances have made it possible to prospect for degrading microorganisms in the environment and to determine the mechanisms involved in biodegradation when xenobiotic polymers are introduced into the environment and are exposed to microbial attack. In this review, the molecular biological and biochemical aspects of the microbial degradation of xenobiotic polymers are summarized, and possible applications of potent microorganisms, enzymes, and genes in environmental biotechnology are suggested.

  4. Xenobiotics: How the Environment Changes Your Body

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Baker, Erin

    Erin Baker studies how substances foreign to your body affect your health. To do so, her team at PNNL developed a rapid way to separate and study both xenobiotics and endogenous molecules using ion mobility.

  5. Neurotoxicity Linked to Dysfunctional Metal Ion Homeostasis and Xenobiotic Metal Exposure: Redox Signaling and Oxidative Stress.

    PubMed

    Garza-Lombó, Carla; Posadas, Yanahi; Quintanar, Liliana; Gonsebatt, María E; Franco, Rodrigo

    2018-06-20

    Essential metals such as copper, iron, manganese, and zinc play a role as cofactors in the activity of a wide range of processes involved in cellular homeostasis and survival, as well as during organ and tissue development. Throughout our life span, humans are also exposed to xenobiotic metals from natural and anthropogenic sources, including aluminum, arsenic, cadmium, lead, and mercury. It is well recognized that alterations in the homeostasis of essential metals and an increased environmental/occupational exposure to xenobiotic metals are linked to several neurological disorders, including neurodegeneration and neurodevelopmental alterations. Recent Advances: The redox activity of essential metals is key for neuronal homeostasis and brain function. Alterations in redox homeostasis and signaling are central to the pathological consequences of dysfunctional metal ion homeostasis and increased exposure to xenobiotic metals. Both redox-active and redox-inactive metals trigger oxidative stress and damage in the central nervous system, and the exact mechanisms involved are starting to become delineated. In this review, we aim to appraise the role of essential metals in determining the redox balance in the brain and the mechanisms by which alterations in the homeostasis of essential metals and exposure to xenobiotic metals disturb the cellular redox balance and signaling. We focus on recent literature regarding their transport, metabolism, and mechanisms of toxicity in neural systems. Delineating the specific mechanisms by which metals alter redox homeostasis is key to understand the pathological processes that convey chronic neuronal dysfunction in neurodegenerative and neurodevelopmental disorders. Antioxid. Redox Signal. 28, 1669-1703.

  6. A Global Genomic and Genetic Strategy to Identify, Validate and Use Gene Signatures of Xenobiotic-Responsive Transcription Factors in Prediction of Pathway Activation in the Mouse Liver

    EPA Science Inventory

    Many drugs and environmentally-relevant chemicals activate xenobiotic-responsive transcription factors. Identification of target genes of these factors would be useful in predicting pathway activation in in vitro chemical screening as well as their involvement in disease states. ...

  7. Targeting the Toll of Drug Abuse: The Translational Potential of Toll-Like Receptor 4

    PubMed Central

    Bachtell, Ryan; Hutchinson, Mark R.; Wang, Xiaohui; Rice, Kenner C.; Maier, Steven F; Watkins, Linda R.

    2017-01-01

    There is growing recognition that glial proinflammatory activation importantly contributes to the rewarding and reinforcing effects of a variety of drugs of abuse, including cocaine, methamphetamine, opioids, and alcohol. It has recently been proposed that glia are recognizing, and becoming activated by, such drugs as a CNS immunological response to these agents being xenobiotics; that is, substances foreign to the brain. Activation of glia, primarily microglia, by various drugs of abuse occurs via toll like receptor 4 (TLR4). The detection of such xenobiotics by TLR4 results in the release of glial neuroexcitatory and neurotoxic substances. These glial products of TLR4 activation enhance neuronal excitability within brain reward circuitry, thereby enhancing their rewarding and reinforcing effects. Indeed, selective pharmacological blockade of TLR4 activation, such as with the non-opioid TLR4 antagonist (+)-naltrexone, suppresses a number of indices of drug reward/reinforcement. These include: conditioned place preference, self-administration, drug-primed reinstatement, incubation of craving, and elevations of nucleus accumbens shell dopamine. Notably, TLR4 blockade fails to alter self-administration of food, indicative of a selective effect on drugs of abuse. Genetic disruption of TLR4 signaling recapitulates the effects of pharmacological TLR4 blockade, providing converging lines of evidence of a central importance of TLR4. Taken together, multiple lines of evidence converge to raise TLR4 as a promising therapeutic target for drug abuse. PMID:26022268

  8. DEVELOPMENT OF MOLECULAR INDICATORS OF EXPOSURE TO ENDOCRINE DISRUPTING COMPOUNDS, PESTICIDES & OTHER XENOBIOTIC AGENTS

    EPA Science Inventory

    A great deal of uncertainty exists regarding the extent to which humans and wildlife are exposed to chemical stressors in aquatic resources. Scientific literature is replete with studies of xenobiotics in surface waters, including a recent national USGS survey of endocrine disrup...

  9. Tools for studying drug transport and metabolism in the brain.

    PubMed

    Pitcher, Meagan R; Quevedo, João

    2016-01-01

    Development of xenobiotics that cross the blood-brain barrier in therapeutically-relevant quantities is an expensive and time-consuming undertaking. However, central nervous system diseases are an under-addressed cause of high mortality and morbidity, and drug development in this field is a worthwhile venture. We aim to familiarize the reader with available methodologies for studying drug transport into the brain. Current understanding of the blood-brain barrier structure has been well-described in other manuscripts, and first we briefly review the path that xenobiotics take through the brain - from bloodstream, to endothelial cells of the blood-brain barrier, to interstitial space, to brain parenchymal cells, and then to an exit point from the central nervous system. The second half of the review discusses research tools available to determine if xenobiotics are making the journey through the brain successfully and offers commentary on the translational utility of each methodology. Theoretically, non-human mammalian and human blood-brain barriers are similar in composition; however, some findings demonstrate important differences across species. Translational methodologies may provide more reliable information about how a drug may act across species. The recent finding of lymphatic vessels within the central nervous system may provide new tools and strategies for drug delivery to the brain.

  10. Symposium overview: alterations in cytokine receptors by xenobiotics.

    PubMed

    Cohen, M D; Schook, L B; Oppenheim, J J; Freed, B M; Rodgers, K E

    1999-04-01

    A symposium entitled Alterations in Cytokine Receptors by Xenobiotics was held at the 37th Annual Meeting of the Society of Toxicology (SOT) in Seattle, Washington. The symposium was sponsored by the Immunotoxicology Specialty Section of SOT and was designed to present information on the effect of several different classes of xenobiotics on various aspects of receptor function (i.e., post-receptor signal transduction of receptor expression), or the involvement of cytokine receptors in the action of the toxicant under consideration. This symposium brought together scientists in the area of receptor immunobiology whose expertise in receptor modulation encompassed those major signaling agents involved in the normal immune response, i.e., proinflammatory cytokines, chemokines, interleukins, and interferons. The following is a summary of each of the individual presentations.

  11. Ecologically Appropriate Xenobiotics Induce Cytochrome P450s in Apis mellifera

    PubMed Central

    Johnson, Reed M.; Mao, Wenfu; Pollock, Henry S.; Niu, Guodong; Schuler, Mary A.; Berenbaum, May R.

    2012-01-01

    Background Honey bees are exposed to phytochemicals through the nectar, pollen and propolis consumed to sustain the colony. They may also encounter mycotoxins produced by Aspergillus fungi infesting pollen in beebread. Moreover, bees are exposed to agricultural pesticides, particularly in-hive acaricides used against the parasite Varroa destructor. They cope with these and other xenobiotics primarily through enzymatic detoxificative processes, but the regulation of detoxificative enzymes in honey bees remains largely unexplored. Methodology/Principal Findings We used several approaches to ascertain effects of dietary toxins on bee susceptibility to synthetic and natural xenobiotics, including the acaricide tau-fluvalinate, the agricultural pesticide imidacloprid, and the naturally occurring mycotoxin aflatoxin. We administered potential inducers of cytochrome P450 enzymes, the principal biochemical system for Phase 1 detoxification in insects, to investigate how detoxification is regulated. The drug phenobarbital induces P450s in many insects, yet feeding bees with phenobarbital had no effect on the toxicity of tau-fluvalinate, a pesticide known to be detoxified by bee P450s. Similarly, no P450 induction, as measured by tau-fluvalinate tolerance, occurred in bees fed xanthotoxin, salicylic acid, or indole-3-carbinol, all of which induce P450s in other insects. Only quercetin, a common pollen and honey constituent, reduced tau-fluvalinate toxicity. In microarray comparisons no change in detoxificative gene expression was detected in phenobarbital-treated bees. However, northern blot analyses of guts of bees fed extracts of honey, pollen and propolis showed elevated expression of three CYP6AS P450 genes. Diet did not influence tau-fluvalinate or imidacloprid toxicity in bioassays; however, aflatoxin toxicity was higher in bees consuming sucrose or high-fructose corn syrup than in bees consuming honey. Conclusions/Significance These results suggest that regulation of

  12. Transgenic plants for enhanced biodegradation and phytoremediation of organic xenobiotics.

    PubMed

    Abhilash, P C; Jamil, Sarah; Singh, Nandita

    2009-01-01

    Phytoremediation--the use of plants to clean up polluted soil and water resources--has received much attention in the last few years. Although plants have the inherent ability to detoxify xenobiotics, they generally lack the catabolic pathway for the complete degradation of these compounds compared to microorganisms. There are also concerns over the potential for the introduction of contaminants into the food chain. The question of how to dispose of plants that accumulate xenobiotics is also a serious concern. Hence the feasibility of phytoremediation as an approach to remediate environmental contamination is still somewhat in question. For these reasons, researchers have endeavored to engineer plants with genes that can bestow superior degradation abilities. A direct method for enhancing the efficacy of phytoremediation is to overexpress in plants the genes involved in metabolism, uptake, or transport of specific pollutants. Furthermore, the expression of suitable genes in root system enhances the rhizodegradation of highly recalcitrant compounds like PAHs, PCBs etc. Hence, the idea to amplify plant biodegradation of xenobiotics by genetic manipulation was developed, following a strategy similar to that used to develop transgenic crops. Genes from human, microbes, plants, and animals are being used successfully for this venture. The introduction of these genes can be readily achieved for many plant species using Agrobacterium tumefaciens-mediated plant transformation or direct DNA methods of gene transfer. One of the promising developments in transgenic technology is the insertion of multiple genes (for phase 1 metabolism (cytochrome P450s) and phase 2 metabolism (GSH, GT etc.) for the complete degradation of the xenobiotics within the plant system. In addition to the use of transgenic plants overexpressed with P450 and GST genes, various transgenic plants expressing bacterial genes can be used for the enhanced degradation and remediation of herbicides, explosives

  13. Alcohol effects on drug-nutrient interactions.

    PubMed

    Seitz, H K

    1985-01-01

    The interaction of ethanol with drugs and xenobiotics is complex because ethanol can affect any of the following steps; absorption, plasma protein binding, hepatic blood flow, distribution, hepatic uptake of drugs, and phase I and II hepatic metabolism. The ingestion of ethanol can lead to malabsorption of a variety of nutrients and can modify the absorption of various drugs. High concentrations of ethanol in conjunction with aspirin causes gastric mucosal damage. The principal effect of acute ethanol ingestion on drug metabolism is inhibition of microsomal drug metabolism. The synergistic effects of ethanol on central nervous system depressants can be explained by this mechanism. In contrast, chronic ethanol consumption increases mixed function oxidation and drug metabolism. The cross tolerance between ethanol and sedatives in chronic alcoholics may be due to this effect of alcohol. In addition, enhanced production of hepatotoxic products from certain drugs and xenobiotics and an increased activation of procarcinogens to carcinogens can result from this microsomal induction. The increased susceptibility to hepatotoxins and the enhanced carcinogenesis in the alcoholic may be explained by this fact. Other effects of the interaction between drugs and ethanol are the result of changes in organ susceptibility, best demonstrated for the central nervous system. Subsequently, the presence of liver disease has a great effect on drug metabolism in alcoholics.

  14. Xenobiotics enhance laccase activity in alkali-tolerant γ-proteobacterium JB.

    PubMed

    Singh, Gursharan; Batish, Mona; Sharma, Prince; Capalash, Neena

    2009-01-01

    Various genotoxic textile dyes, xenobiotics, substrates (10 µM) and agrochemicals (100 µg/ml) were tested for enhancement of alkalophilic laccase activity in γ-proteobacterium JB. Neutral Red, Indigo Carmine, Naphthol Base Bordears and Sulphast Ruby dyes increased the activity by 3.7, 2.7, 2.6 and 2.3 fold respectively. Xenobiotics/substrates like p-toluidine, 8-hydroxyquinoline and anthracine increased it by 3.4, 2.8 and 2.3 fold respectively. Atrazine and trycyclozole pesticides enhanced the activity by 1.95 and 1.5 fold respectively.

  15. Xenobiotics enhance laccase activity in alkali-tolerant γ-proteobacterium JB

    PubMed Central

    Singh, Gursharan; Batish, Mona; Sharma, Prince; Capalash, Neena

    2009-01-01

    Various genotoxic textile dyes, xenobiotics, substrates (10 µM) and agrochemicals (100 µg/ml) were tested for enhancement of alkalophilic laccase activity in γ-proteobacterium JB. Neutral Red, Indigo Carmine, Naphthol Base Bordears and Sulphast Ruby dyes increased the activity by 3.7, 2.7, 2.6 and 2.3 fold respectively. Xenobiotics/substrates like p-toluidine, 8-hydroxyquinoline and anthracine increased it by 3.4, 2.8 and 2.3 fold respectively. Atrazine and trycyclozole pesticides enhanced the activity by 1.95 and 1.5 fold respectively. PMID:24031313

  16. Research Resource: A Reference Transcriptome for Constitutive Androstane Receptor and Pregnane X Receptor Xenobiotic Signaling

    PubMed Central

    Ochsner, Scott A.; Tsimelzon, Anna; Dong, Jianrong; Coarfa, Cristian

    2016-01-01

    The pregnane X receptor (PXR) (PXR/NR1I3) and constitutive androstane receptor (CAR) (CAR/NR1I2) members of the nuclear receptor (NR) superfamily of ligand-regulated transcription factors are well-characterized mediators of xenobiotic and endocrine-disrupting chemical signaling. The Nuclear Receptor Signaling Atlas maintains a growing library of transcriptomic datasets involving perturbations of NR signaling pathways, many of which involve perturbations relevant to PXR and CAR xenobiotic signaling. Here, we generated a reference transcriptome based on the frequency of differential expression of genes across 159 experiments compiled from 22 datasets involving perturbations of CAR and PXR signaling pathways. In addition to the anticipated overrepresentation in the reference transcriptome of genes encoding components of the xenobiotic stress response, the ranking of genes involved in carbohydrate metabolism and gonadotropin action sheds mechanistic light on the suspected role of xenobiotics in metabolic syndrome and reproductive disorders. Gene Set Enrichment Analysis showed that although acetaminophen, chlorpromazine, and phenobarbital impacted many similar gene sets, differences in direction of regulation were evident in a variety of processes. Strikingly, gene sets representing genes linked to Parkinson's, Huntington's, and Alzheimer's diseases were enriched in all 3 transcriptomes. The reference xenobiotic transcriptome will be supplemented with additional future datasets to provide the community with a continually updated reference transcriptomic dataset for CAR- and PXR-mediated xenobiotic signaling. Our study demonstrates how aggregating and annotating transcriptomic datasets, and making them available for routine data mining, facilitates research into the mechanisms by which xenobiotics and endocrine-disrupting chemicals subvert conventional NR signaling modalities. PMID:27409825

  17. Research Resource: A Reference Transcriptome for Constitutive Androstane Receptor and Pregnane X Receptor Xenobiotic Signaling.

    PubMed

    Ochsner, Scott A; Tsimelzon, Anna; Dong, Jianrong; Coarfa, Cristian; McKenna, Neil J

    2016-08-01

    The pregnane X receptor (PXR) (PXR/NR1I3) and constitutive androstane receptor (CAR) (CAR/NR1I2) members of the nuclear receptor (NR) superfamily of ligand-regulated transcription factors are well-characterized mediators of xenobiotic and endocrine-disrupting chemical signaling. The Nuclear Receptor Signaling Atlas maintains a growing library of transcriptomic datasets involving perturbations of NR signaling pathways, many of which involve perturbations relevant to PXR and CAR xenobiotic signaling. Here, we generated a reference transcriptome based on the frequency of differential expression of genes across 159 experiments compiled from 22 datasets involving perturbations of CAR and PXR signaling pathways. In addition to the anticipated overrepresentation in the reference transcriptome of genes encoding components of the xenobiotic stress response, the ranking of genes involved in carbohydrate metabolism and gonadotropin action sheds mechanistic light on the suspected role of xenobiotics in metabolic syndrome and reproductive disorders. Gene Set Enrichment Analysis showed that although acetaminophen, chlorpromazine, and phenobarbital impacted many similar gene sets, differences in direction of regulation were evident in a variety of processes. Strikingly, gene sets representing genes linked to Parkinson's, Huntington's, and Alzheimer's diseases were enriched in all 3 transcriptomes. The reference xenobiotic transcriptome will be supplemented with additional future datasets to provide the community with a continually updated reference transcriptomic dataset for CAR- and PXR-mediated xenobiotic signaling. Our study demonstrates how aggregating and annotating transcriptomic datasets, and making them available for routine data mining, facilitates research into the mechanisms by which xenobiotics and endocrine-disrupting chemicals subvert conventional NR signaling modalities.

  18. GENE EXPRESSION PROFILING IN AGING RATS AND MICE REVEALS CHANGES IN XENOBIOTIC METABOLISM GENES

    EPA Science Inventory

    Detoxification and elimination of xenobiotics are major functions of the liver and is important in maintaining the metabolic homeostasis of the organism. The degree to which aging affects hepatic metabolism is not known. The expression of xenobiotic metabolizing enzymes (XMEs), i...

  19. Rb and p53 Liver Functions Are Essential for Xenobiotic Metabolism and Tumor Suppression

    PubMed Central

    Nantasanti, Sathidpak; Toussaint, Mathilda J. M.; Youssef, Sameh A.; Tooten, Peter C. J.; de Bruin, Alain

    2016-01-01

    The tumor suppressors Retinoblastoma (Rb) and p53 are frequently inactivated in liver diseases, such as hepatocellular carcinomas (HCC) or infections with Hepatitis B or C viruses. Here, we discovered a novel role for Rb and p53 in xenobiotic metabolism, which represent a key function of the liver for metabolizing therapeutic drugs or toxins. We demonstrate that Rb and p53 cooperate to metabolize the xenobiotic 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). DDC is metabolized mainly by cytochrome P450 (Cyp)3a enzymes resulting in inhibition of heme synthesis and accumulation of protoporphyrin, an intermediate of heme pathway. Protoporphyrin accumulation causes bile injury and ductular reaction. We show that loss of Rb and p53 resulted in reduced Cyp3a expression decreased accumulation of protoporphyrin and consequently less ductular reaction in livers of mice fed with DDC for 3 weeks. These findings provide strong evidence that synergistic functions of Rb and p53 are essential for metabolism of DDC. Because Rb and p53 functions are frequently disabled in liver diseases, our results suggest that liver patients might have altered ability to remove toxins or properly metabolize therapeutic drugs. Strikingly the reduced biliary injury towards the oxidative stress inducer DCC was accompanied by enhanced hepatocellular injury and formation of HCCs in Rb and p53 deficient livers. The increase in hepatocellular injury might be related to reduce protoporphyrin accumulation, because protoporphrin is well known for its anti-oxidative activity. Furthermore our results indicate that Rb and p53 not only function as tumor suppressors in response to carcinogenic injury, but also in response to non-carcinogenic injury such as DDC. PMID:26967735

  20. Detoxification function of the Arabidopsis sulphotransferase AtSOT12 by sulphonation of xenobiotics.

    PubMed

    Chen, Jinhua; Gao, Liqiong; Baek, Dongwon; Liu, Chunlin; Ruan, Ying; Shi, Huazhong

    2015-08-01

    Cytosolic sulphotransferases have been implicated in inactivation of endogenous steroid hormones and detoxification of xenobiotics in human and animals. Yet, the function of plant sulphotransferases in xenobiotic sulphonation and detoxification has not been reported. In this study, we show that the Arabidopsis sulphotransferase AtSOT12 could sulphonate the bacterial-produced toxin cycloheximide. Loss-of-function mutant sot12 exhibited hypersensitive phenotype to cycloheximide, and expression of AtSOT12 protein in yeast cells conferred resistance to this toxic compound. AtSOT12 exhibited broad specificity and could sulphonate a variety of xenobiotics including phenolic and polycyclic compounds. Enzyme kinetics analysis indicated that AtSOT12 has different selectivity for simple phenolics with different side chains, and the position of the side chain in the simple phenolic compounds affects substrate binding affinity and catalytic efficiency. We proposed that the broad specificity and induced production of AtSOT12 may have rendered this enzyme to not only modify endogenous molecules such as salicylic acid as we previously reported, but also sulphonate pathogen-produced toxic small molecules to protect them from infection. Sulphonation of small molecules in plants may constitute a rapid way to inactivate or change the physiochemical properties of biologically active molecules that could have profound effects on plant growth, development and defence. © 2015 John Wiley & Sons Ltd.

  1. A single amino acid controls the functional switch of human constitutive androstane receptor (CAR) 1 to the xenobiotic-sensitive splicing variant CAR3.

    PubMed

    Chen, Tao; Tompkins, Leslie M; Li, Linhao; Li, Haishan; Kim, Gregory; Zheng, Yuxin; Wang, Hongbing

    2010-01-01

    The constitutive androstane receptor (CAR) is constitutively activated in immortalized cell lines independent of xenobiotic stimuli. This feature of CAR has limited its use as a sensor for xenobiotic-induced expression of drug-metabolizing enzymes. Recent reports, however, reveal that a splicing variant of human CAR (hCAR3), which contains an insertion of five amino acids (APYLT), exhibits low basal but xenobiotic-inducible activities in cell-based reporter assays. Nonetheless, the underlying mechanisms of this functional shift are not well understood. We have now generated chimeric constructs containing various residues of the five amino acids of hCAR3 and examined their response to typical hCAR activators. Our results showed that the retention of alanine (hCAR1+A) alone is sufficient to confer the constitutively activated hCAR1 to the xenobiotic-sensitive hCAR3. It is noteworthy that hCAR1+A was significantly activated by a series of known hCAR activators, and displayed activation superior to that of hCAR3. Moreover, intracellular localization assays revealed that hCAR1+A exhibits nuclear accumulation upon 6-(4-chlorophenyl) imidazo[2,1-b][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl) oxime (CITCO) treatment in COS1 cells, which differs from the spontaneous nuclear distribution of hCAR1 and the nontranslocatable hCAR3. Mammalian two-hybrid and glutathione S-transferase pull-down assays further demonstrated that hCAR1+A interacts with the coactivator SRC-1 and GRIP-1 at low level before activation, while at significantly enhanced level in the presence of CITCO. Thus, the alanine residue in the insertion of hCAR3 seems in charge of the xenobiotic response of hCAR3 through direct and indirect mechanisms. Activation of hCAR1+A may represent a sensitive avenue for the identification of hCAR activators.

  2. A Single Amino Acid Controls the Functional Switch of Human Constitutive Androstane Receptor (CAR) 1 to the Xenobiotic-Sensitive Splicing Variant CAR3

    PubMed Central

    Chen, Tao; Tompkins, Leslie M.; Li, Linhao; Li, Haishan; Kim, Gregory; Zheng, Yuxin

    2010-01-01

    The constitutive androstane receptor (CAR) is constitutively activated in immortalized cell lines independent of xenobiotic stimuli. This feature of CAR has limited its use as a sensor for xenobiotic-induced expression of drug-metabolizing enzymes. Recent reports, however, reveal that a splicing variant of human CAR (hCAR3), which contains an insertion of five amino acids (APYLT), exhibits low basal but xenobiotic-inducible activities in cell-based reporter assays. Nonetheless, the underlying mechanisms of this functional shift are not well understood. We have now generated chimeric constructs containing various residues of the five amino acids of hCAR3 and examined their response to typical hCAR activators. Our results showed that the retention of alanine (hCAR1+A) alone is sufficient to confer the constitutively activated hCAR1 to the xenobiotic-sensitive hCAR3. It is noteworthy that hCAR1+A was significantly activated by a series of known hCAR activators, and displayed activation superior to that of hCAR3. Moreover, intracellular localization assays revealed that hCAR1+A exhibits nuclear accumulation upon 6-(4-chlorophenyl) imidazo[2,1-b][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl) oxime (CITCO) treatment in COS1 cells, which differs from the spontaneous nuclear distribution of hCAR1 and the nontranslocatable hCAR3. Mammalian two-hybrid and glutathione S-transferase pull-down assays further demonstrated that hCAR1+A interacts with the coactivator SRC-1 and GRIP-1 at low level before activation, while at significantly enhanced level in the presence of CITCO. Thus, the alanine residue in the insertion of hCAR3 seems in charge of the xenobiotic response of hCAR3 through direct and indirect mechanisms. Activation of hCAR1+A may represent a sensitive avenue for the identification of hCAR activators. PMID:19820207

  3. Removal of xenobiotics from effluent discharge by adsorption on zeolite and expanded clay: an alternative to activated carbon?

    PubMed

    Tahar, A; Choubert, J M; Miège, C; Esperanza, M; Le Menach, K; Budzinski, H; Wisniewski, C; Coquery, M

    2014-04-01

    Xenobiotics such as pesticides and pharmaceuticals are an increasingly large problem in aquatic environments. A fixed-bed adsorption filter, used as tertiary stage of sewage treatment, could be a solution to decrease xenobiotics concentrations in wastewater treatment plants (WWTPs) effluent. The adsorption efficiency of two mineral adsorbent materials (expanded clay (EC) and zeolite (ZE)), both seen as a possible alternative to activated carbon (AC), was evaluated in batch tests. Experiments involving secondary treated domestic wastewater spiked with a cocktail of ten xenobiotics (eight pharmaceuticals and two pesticides) known to be poorly eliminated in conventional biological process were carried out. Removal efficiencies and partitions coefficients were calculated for two levels of initial xenobiotic concentration, i.e, concentrations lower to 10 μg/L and concentrations ranged from 100 to 1,000 μg/L. While AC was the most efficient adsorbent material, both alternative adsorbent materials showed good adsorption efficiencies for all ten xenobiotics (from 50 to 100 % depending on the xenobiotic/adsorbent material pair). For all the targeted xenobiotics, at lower concentrations, EC presented the best adsorption potential with higher partition coefficients, confirming the results in terms of removal efficiencies. Nevertheless, Zeolite presents virtually the same adsorption potential for both high and low xenobiotics concentrations to be treated. According to this first batch investigation, ZE and EC could be used as alternative absorbent materials to AC in WWTP.

  4. Targeting efflux pumps to overcome antifungal drug resistance

    PubMed Central

    Holmes, Ann R; Cardno, Tony S; Strouse, J Jacob; Ivnitski-Steele, Irena; Keniya, Mikhail V; Lackovic, Kurt; Monk, Brian C; Sklar, Larry A; Cannon, Richard D

    2016-01-01

    Resistance to antifungal drugs is an increasingly significant clinical problem. The most common antifungal resistance encountered is efflux pump-mediated resistance of Candida species to azole drugs. One approach to overcome this resistance is to inhibit the pumps and chemosensitize resistant strains to azole drugs. Drug discovery targeting fungal efflux pumps could thus result in the development of azole-enhancing combination therapy. Heterologous expression of fungal efflux pumps in Saccharomyces cerevisiae provides a versatile system for screening for pump inhibitors. Fungal efflux pumps transport a range of xenobiotics including fluorescent compounds. This enables the use of fluorescence-based detection, as well as growth inhibition assays, in screens to discover compounds targeting efflux-mediated antifungal drug resistance. A variety of medium- and high-throughput screens have been used to identify a number of chemical entities that inhibit fungal efflux pumps. PMID:27463566

  5. Quantitation of cytokine mRNA expression as an endpoint for prediction and diagnosis of xenobiotic-induced hypersensitivity reactions.

    PubMed

    Gaspard, I; Kerdine, S; Pallardy, M; Lebrec, H

    1999-09-01

    Xenobiotic-induced hypersensitivity reactions are immune-mediated effects that involve specific antibodies and/or effector and regulatory T lymphocytes. Cytokines are key mediators of such responses and must be considered as possible endpoints for predicting sensitizing potency of drugs and chemicals, as well as for helping diagnosis of allergy. Detecting cytokine production at the protein level has been shown to not be always sensitive enough. This paper describes three examples of the utilization of semiquantitative or competitive reverse transcription polymerase chain reaction analysis of interleukin-4, interferon gamma, and interleukin-1beta mRNAs as endpoints for assessing T-cell or dendritic cell responses to sensitizing drugs (beta-lactam antibiotics) or chemicals (dinitrochlorobenzene). Copyright 1999 Academic Press.

  6. An activated sludge modeling framework for xenobiotic trace chemicals (ASM-X): assessment of diclofenac and carbamazepine.

    PubMed

    Plósz, Benedek Gy; Langford, Katherine H; Thomas, Kevin V

    2012-11-01

    Conventional models for predicting the fate of xenobiotic organic trace chemicals, identified, and calibrated using data obtained in batch experiments spiked with reference substances, can be limited in predicting xenobiotic removal in wastewater treatment plants (WWTPs). At stake is the level of model complexity required to adequately describe a general theory of xenobiotic removal in WWTPs. In this article, we assess the factors that influence the removal of diclofenac and carbamazepine in activated sludge, and evaluate the complexity required for the model to effectively predict their removal. The results are generalized to previously published cases. Batch experimental results, obtained under anoxic and aerobic conditions, were used to identify extensions to, and to estimate parameter values of the activated sludge modeling framework for Xenobiotic trace chemicals (ASM-X). Measurement and simulation results obtained in the batch experiments, spiked with the diclofenac and carbamazepine content of preclarified municipal wastewater shows comparably high biotransformation rates in the presence of growth substrates. Forward dynamic simulations were performed using full-scale data obtained from Bekkelaget WWTP (Oslo, Norway) to evaluate the model and to estimate the level of re-transformable xenobiotics present in the influent. The results obtained in this study demonstrate that xenobiotic loading conditions can significantly influence the removal capacity of WWTPs. We show that the trace chemical retransformation in upstream sewer pipes can introduce considerable error in assessing the removal efficiency of a WWTP, based only on parent compound concentration measurements. The combination of our data with those from the literature shows that solids retention time (SRT) can enhance the biotransformation of diclofenac, which was not the case for carbamazepine. Model approximation of the xenobiotic concentration, detected in the solid phase, suggest that between

  7. Xenobiotics that affect oxidative phosphorylation alter differentiation of human adipose-derived stem cells at concentrations that are found in human blood

    PubMed Central

    Llobet, Laura; Toivonen, Janne M.; Montoya, Julio; Ruiz-Pesini, Eduardo; López-Gallardo, Ester

    2015-01-01

    ABSTRACT Adipogenesis is accompanied by differentiation of adipose tissue-derived stem cells to adipocytes. As part of this differentiation, biogenesis of the oxidative phosphorylation system occurs. Many chemical compounds used in medicine, agriculture or other human activities affect oxidative phosphorylation function. Therefore, these xenobiotics could alter adipogenesis. We have analyzed the effects on adipocyte differentiation of some xenobiotics that act on the oxidative phosphorylation system. The tested concentrations have been previously reported in human blood. Our results show that pharmaceutical drugs that decrease mitochondrial DNA replication, such as nucleoside reverse transcriptase inhibitors, or inhibitors of mitochondrial protein synthesis, such as ribosomal antibiotics, diminish adipocyte differentiation and leptin secretion. By contrast, the environmental chemical pollutant tributyltin chloride, which inhibits the ATP synthase of the oxidative phosphorylation system, can promote adipocyte differentiation and leptin secretion, leading to obesity and metabolic syndrome as postulated by the obesogen hypothesis. PMID:26398948

  8. Orphan Nuclear Receptors as Targets for Drug Development

    PubMed Central

    Mukherjee, Subhajit

    2012-01-01

    Orphan nuclear receptors regulate diverse biological processes. These important molecules are ligand-activated transcription factors that act as natural sensors for a wide range of steroid hormones and xenobiotic ligands. Because of their importance in regulating various novel signaling pathways, recent research has focused on identifying xenobiotics targeting these receptors for the treatment of multiple human diseases. In this review, we will highlight these receptors in several physiologic and pathophysiologic actions and demonstrate how their functions can be exploited for the successful development of newer drugs. PMID:20372994

  9. Two horizontally transferred xenobiotic resistance gene clusters associated with detoxification of benzoxazolinones by Fusarium species

    USDA-ARS?s Scientific Manuscript database

    Microbes encounter a broad spectrum of chemical compounds in their diverse environments. These xenobiotics may negatively impact growth or cause death. To counter such adverse effects, many microbes possess metabolic strategies to detoxify and biotransform xenobiotics. Fusarium verticillioides is a ...

  10. Nontargeted analysis of the urine nonpolar sulfateome: a pathway to the nonpolar xenobiotic exposome

    PubMed Central

    Yao, Yuanyuan; Wang, Poguang; Shao, Gang; Anzalota Del Toro, Liza V.; Codero, Jose; Giese, Roger W.

    2016-01-01

    RATIONALE Testing the urine nonpolar sulfateome can enable discovery of xenobiotics that are most likely to be bioactive. This is based on the fact that nonpolar xenobiotics are more likely to enter cells where they tend to undergo metabolism, in part, to sulfates that are then largely excreted into the urine. METHODS The following sequence of steps, with conditions that achieve high reproducibility, was applied to large human urine samples: (1) competitive nonpolar extraction with a porous extraction paddle; (2) weak anion exchange extraction with strong organic washing; and (3) UHPLC/negative ion-MALDI-TOF/TOF-MS with recording of ions with S/N ≥ 20 that yielded M-1-80 (loss of SO3) or m/z 97 (HSO4−) upon fragmentation. RESULTS From a collection of urine samples from six pregnant women, the masses of 1129 putative sulfates were measured. Three lists of candidate compounds (preliminary hits) from these masses were formed by searching METLIN, especially via MATLAB, yielding putative xenobiotic contaminants (35 compounds), steroids (122), and flavonoids (1582). CONCLUSION A new way to reveal some of the nonpolar xenobiotic exposome has been developed that applies to urine samples. The value of the method is to suggest xenobiotics for subsequent targeted analysis in the population of people under study, in order to relate the environment to health and disease. PMID:27557133

  11. Review and evaluation of the effects of xenobiotic chemicals on microorganisms in soil. [139 references

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hicks, R.J.; Van Voris, P.

    1988-02-01

    The primary objective was to review and evaluate the relevance and quality of existing xenobiotic data bases and test methods for evaluating direct and indirect effects (both adverse and beneficial) of xenobiotics on the soil microbial community; direct and indirect effects of the soil microbial community on xenobiotics; and adequacy of test methods used to evaluate these effects and interactions. Xenobiotic chemicals are defined here as those compounds, both organic and inorganic, produced by man and introduced into the environment at concentrations that cause undesirable effects. Because soil serves as the main repository for many of these chemicals, it thereforemore » has a major role in determining their ultimate fate. Once released, the distribution of xenobiotics between environmental compartments depends on the chemodynamic properties of the compounds, the physicochemical properties of the soils, and the transfer between soil-water and soil-air interfaces and across biological membranes. Abiotic and biotic processes can transform the chemical compound, thus altering its chemical state and, subsequently, its toxicity and reactivity. Ideally, the conversion is to carbon dioxide, water, and mineral elements, or at least, to some harmless substance. However, intermediate transformation products, which can become toxic pollutants in their own right, can sometimes be formed. 139 refs., 6 figs., 11 tabs.« less

  12. The role of the placenta in drug transport and fetal drug exposure.

    PubMed

    Koren, Gideon; Ornoy, Asher

    2018-04-01

    It was assumed for decades that the human placenta serves as a barrier, protecting the fetus from exposure to xenobiotics circulating in the mother. The thalidomide disaster completely reversed this concept. The study of the human placenta is therefore critical to understanding the mechanisms by which xenobiotics reach the fetus and exert their effects. Areas covered: This review describes mechanisms by which drugs interact with the human placenta, and experimental methods to study these interactions in humans. We have selected three areas of current clinical interest, where the placenta exhibits critical role in drug transport: The ABC transporters, the placental handling of cancer therapeutic drugs and the interaction between the placenta and immunoglobulins. Expert commentary: The optimal model to predict drug transfer and transport from the mother to the fetus is the isolated human placental lobule perfused in vitro. Unlike subcellular preparations or tissue homogenates, data obtained from a perfused intact tissue, where structural integrity and cell-cell organization are maintained, more closely reflect the in vivo situation. Moreover, confounding metabolic and physiologic influences are minimized and the experimental conditions can be controlled. It is important to remember that due to significant differences in the function of the placenta in the first two months (histiotrophic nutrition) and later in pregnancy (hemotrophic nutrition) there might be differences in the transplacental transfer of drugs. While most of our knowledge comes from studies on term placentae, we are in need of studies on young placenta that functions during the period of organogenesis.

  13. Chimeric mice with humanized liver: Application in drug metabolism and pharmacokinetics studies for drug discovery.

    PubMed

    Naritomi, Yoichi; Sanoh, Seigo; Ohta, Shigeru

    2018-02-01

    Predicting human drug metabolism and pharmacokinetics (PK) is key to drug discovery. In particular, it is important to predict human PK, metabolite profiles and drug-drug interactions (DDIs). Various methods have been used for such predictions, including in vitro metabolic studies using human biological samples, such as hepatic microsomes and hepatocytes, and in vivo studies using experimental animals. However, prediction studies using these methods are often inconclusive due to discrepancies between in vitro and in vivo results, and interspecies differences in drug metabolism. Further, the prediction methods have changed from qualitative to quantitative to solve these issues. Chimeric mice with humanized liver have been developed, in which mouse liver cells are mostly replaced with human hepatocytes. Since human drug metabolizing enzymes are expressed in the liver of these mice, they are regarded as suitable models for mimicking the drug metabolism and PK observed in humans; therefore, these mice are useful for predicting human drug metabolism and PK. In this review, we discuss the current state, issues, and future directions of predicting human drug metabolism and PK using chimeric mice with humanized liver in drug discovery. Copyright © 2017 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  14. In-vitro synthesis of drug metabolites and their screening/characterization using liquid chromatography-mass spectrometry (LC-MS)

    USDA-ARS?s Scientific Manuscript database

    Drug metabolism is a biochemical process by which drugs and xenobiotics are chemically modified to metabolites, primarily by liver enzymes. Metabolites may sometimes affect cellular therapeutic or toxicological processes, therefore knowledge of metabolic processes is essential for understanding drug...

  15. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. [Data-mining characteristics of adverse drug reactions and pharmacovi-gilance of Chinese patent drugs including Aconitum herbs].

    PubMed

    Zhang, Xiao-Meng; Li, Fan; Zhang, Bing; Chen, Xiao-Fen; Piao, Jing-Zhu

    2018-01-01

    The common Aconitum herbs in clinical application mainly include Aconiti Radix(Chuanwu), Aconiti Kusnezoffii Radix(Caowu) and Aconiti Lateralis Radix Praeparaia(Fuzi), all of which have toxicity. Therefore, the safety of using Chinese patent drugs including Aconitum herbs has become an hot topic in clinical controversy. Based on the data-mining methods, this study explored the characteristics and causes of adverse drug reactions/events (ADR/ADE) of the Chinese patent drugs including Aconitum, in order to provide pharmacovigilance and rational drug use suggestions for clinical application. The detailed ADR/ADE reports about the Chinese patent drugs including Aconitum herbs were retrieved in the domestic literature databases since 1984 to now. The information extraction and data-mining were conducted based on the platforms of Microsoft office Excel 2016, Clementine 12.0 and Cytoscape 3.3.0. Finally, 78 detailed ADR/ADE reports involving a total of 30 varieties were included. 92.31% ADR/ADE were surely or likely led by the Chinese patent drugs including Aconitum, mostly involving multiple system/organ damages with good prognosis, and even 1 case of death. The incidence of included ADRs/ADEs was associated with various factors such as the patient idiosyncratic, drug toxicity, as well as clinical medication. The patient age was most closely related to ADR/ADEs, and those aged from 60 to 69 were more easily suffered from the ADRs/ADEs of Chinese patent drugs including Aconitum. The probability of ADR/ADEs for the drugs including Chuanwu or Caowu was greater than that of Fuzi, and the using beyond the instructions dose was the most important potential safety hazard in the clinical medication process. For the regular and characteristics of ADR/ADEs led by Chinese patent drugs including Aconitum, special attention shall be paid to the elder patients or with the patients with allergies; strictly control the dosage and course of treatment, strengthen the safety medication

  17. Xenobiotic-induced apoptosis: significance and potential application as a general biomarker of response

    USGS Publications Warehouse

    Sweet, Leonard I.; Passino-Reader, Dora R.; Meier, Peter G.; Omann, Geneva M.

    1999-01-01

    The process of apoptosis, often coined programmed cell death, involves cell injury induced by a variety of stimuli including xenobiotics and is morphologically, biochemically, and physiologically distinct from necrosis. Apoptotic death is characterized by cellular changes such as cytoplasm shrinkage, chromatin condensation, and plasma membrane asymmetry. This form of cell suicide is appealing as a general biomarker of response in that it is expressed in multiple cell systems (e.g. immune, neuronal, hepatal, intestinal, dermal, reproductive), is conserved phylogenetically (e.g. fish, rodents, birds, sheep, amphibians, roundworms, plants, humans), is modulated by environmentally relevant levels of chemical contaminants, and indicates a state of stress of the organism. Further, apoptosis is useful as a biomarker as it serves as a molecular control point and hence may provide mechanistic information on xenobiotic stress. Studies reviewed here suggest that apoptosis is a sensitive and early indicator of acute and chronic chemical stress, loss of cellular function and structure, and organismal health. Examples are provided of the application of this methodology in studies of health of lake trout (Salvelinus namaycush) in the Laurentian Great Lakes.

  18. Xenobiotic effects on intestinal stem cell proliferation in adult honey bee (Apis mellifera L) workers.

    PubMed

    Forkpah, Cordelia; Dixon, Luke R; Fahrbach, Susan E; Rueppell, Olav

    2014-01-01

    The causes of the current global decline in honey bee health are unknown. One major group of hypotheses invokes the pesticides and other xenobiotics to which this important pollinator species is often exposed. Most studies have focused on mortality or behavioral deficiencies in exposed honey bees while neglecting other biological functions and target organs. The midgut epithelium of honey bees presents an important interface between the insect and its environment. It is maintained by proliferation of intestinal stem cells throughout the adult life of honey bees. We used caged honey bees to test multiple xenobiotics for effects on the replicative activity of the intestinal stem cells under laboratory conditions. Most of the tested compounds did not alter the replicative activity of intestinal stem cells. However, colchicine, methoxyfenozide, tetracycline, and a combination of coumaphos and tau-fluvalinate significantly affected proliferation rate. All substances except methoxyfenozide decreased proliferation rate. Thus, the results indicate that some xenobiotics frequently used in apiculture and known to accumulate in honey bee hives may have hitherto unknown physiological effects. The nutritional status and the susceptibility to pathogens of honey bees could be compromised by the impacts of xenobiotics on the maintenance of the midgut epithelium. This study contributes to a growing body of evidence that more comprehensive testing of xenobiotics may be required before novel or existing compounds can be considered safe for honey bees and other non-target species.

  19. Xenobiotic Effects on Intestinal Stem Cell Proliferation in Adult Honey Bee (Apis mellifera L) Workers

    PubMed Central

    Forkpah, Cordelia; Dixon, Luke R.; Fahrbach, Susan E.; Rueppell, Olav

    2014-01-01

    The causes of the current global decline in honey bee health are unknown. One major group of hypotheses invokes the pesticides and other xenobiotics to which this important pollinator species is often exposed. Most studies have focused on mortality or behavioral deficiencies in exposed honey bees while neglecting other biological functions and target organs. The midgut epithelium of honey bees presents an important interface between the insect and its environment. It is maintained by proliferation of intestinal stem cells throughout the adult life of honey bees. We used caged honey bees to test multiple xenobiotics for effects on the replicative activity of the intestinal stem cells under laboratory conditions. Most of the tested compounds did not alter the replicative activity of intestinal stem cells. However, colchicine, methoxyfenozide, tetracycline, and a combination of coumaphos and tau-fluvalinate significantly affected proliferation rate. All substances except methoxyfenozide decreased proliferation rate. Thus, the results indicate that some xenobiotics frequently used in apiculture and known to accumulate in honey bee hives may have hitherto unknown physiological effects. The nutritional status and the susceptibility to pathogens of honey bees could be compromised by the impacts of xenobiotics on the maintenance of the midgut epithelium. This study contributes to a growing body of evidence that more comprehensive testing of xenobiotics may be required before novel or existing compounds can be considered safe for honey bees and other non-target species. PMID:24608542

  20. In silico identification and construction of microbial gene clusters associated with biodegradation of xenobiotic compounds.

    PubMed

    Awasthi, Garima; Kumari, Anjani; Pant, Aditya Bhushan; Srivastava, Prachi

    2018-01-01

    Chemical substances not showing any importance in existence of biological systems and causing serious health hazards may be designated as Xenobiotic compound. Elimination or degradation of these unwanted substances is a major issue of concern for current time research. Process of biodegradation is a very important aspect of current research as discussed in current manuscript. Current study focuses on the detailed mining of data for the construction of microbial consortia for wide range of xenobiotics compounds. Intensive literature search was done for the construction of this library. Desired data was retrieved from NCBI in fasta format. Data was analysed through homology approaches by using BLAST. This homology based searched enriched with a great vision that not only bacterial population but many other cheap and potential sources are available for different xenobiotic degradation. Though it was focused that bacterial population covers a major part of biodegradation which is near about 90.6% but algae and fungi are also showing promising future in degradation of some important xenobiotic compounds. Analysis of data reveals that Pseudomonas putida has potential for degrading maximum compounds. Establishment of correlation through cluster analysis signifies that Pseudomonas putida, Aspergillus niger and Skeletonema costatum can have combined traits that can be used in finding out actual evolutionary relationship between these species. These findings may also givea new outcome in terms of much cheaper and eco-friendly source in the area of biodegradation of specified xenobiotic compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. 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.

  2. Influence of xenobiotics on the microbiological and agrochemical parameters of soddy-podzolic soil

    NASA Astrophysics Data System (ADS)

    Vakkerov-Kouzova, N. D.

    2010-08-01

    We studied the influence of various chemical compounds, i.e., azobenzene (an insecticide and acaricide), nitrification inhibitors (DCD, dicyandiamide and DMPP, and 3,4-dimetylpyrazolphosphate), and inhibitors of urease activity (HQ-hydroquinone), on the agrochemical and microbiological parameters of a soddy-podzolic soil. It is proved that these xenobiotics are able to influence the agrochemical parameters (the pH and the content of NO{3/-} and NH{4/+}, the microbial activity (the basal respiration, the microbial mass carbon, and the microbial quotient), and the number of bacteria of different physiological groups in soddypodzolic soil. The influence of the xenobiotics was preserved for some time, which testified to their persistence in the soil. Upon cultivating the soil microorganisms in different media, the growth of the heterotrophic bacteria was inhibited, the radial growth velocity was slowed down, and the sporogenesis of the micromycetes was retarded. The toxic effect of the xenobiotics was higher with their increasing concentrations.

  3. Carcinogen-induced mdr overexpression is associated with xenobiotic resistance in rat preneoplastic liver nodules and hepatocellular carcinomas.

    PubMed

    Fairchild, C R; Ivy, S P; Rushmore, T; Lee, G; Koo, P; Goldsmith, M E; Myers, C E; Farber, E; Cowan, K H

    1987-11-01

    We have previously reported the isolation of a human breast cancer cell line resistant to doxorubicin (adriamycin; AdrR MCF-7 cells) that has also developed the phenotype of multidrug resistance (MDR). MDR in this cell line is associated with increased expression of mdr (P glycoprotein) gene sequences. The development of MDR in AdrR MCF-7 cells is also associated with changes in the expression of several phase I and phase II drug-detoxifying enzymes. These changes are remarkably similar to those associated with development of xenobiotic resistance in rat hyperplastic liver nodules, a well-studied model system of chemical carcinogenesis. Using an mdr-encoded cDNA sequence isolated from AdrR MCF-7 cells, we have examined the expression of mdr sequences in rat livers under a variety of experimental conditions. The expression of mdr increased 3-fold in regenerating liver. It was also elevated (3- to 12-fold) in several different samples of rat hyperplastic nodules and in four of five hepatomas that developed in this system. This suggests that overexpression of mdr, a gene previously associated with resistance to antineoplastic agents, may also be involved in the development of resistance to xenobiotics in rat hyperplastic nodules. In addition, although the acute administration of 2-acetylaminofluorene induced an 8-fold increase in hepatic mdr-encoded RNA, performance of a partial hepatectomy either before or after administration of 2-acetylaminofluorene resulted in a greater than 80-fold increase in mdr gene expression over that in normal untreated livers. This represents an important in vivo model system in which to study the acute regulation of this drug resistance gene.

  4. Species differences in drug glucuronidation: Humanized UDP-glucuronosyltransferase 1 mice and their application for predicting drug glucuronidation and drug-induced toxicity in humans.

    PubMed

    Fujiwara, Ryoichi; Yoda, Emiko; Tukey, Robert H

    2018-02-01

    More than 20% of clinically used drugs are glucuronidated by a microsomal enzyme UDP-glucuronosyltransferase (UGT). Inhibition or induction of UGT can result in an increase or decrease in blood drug concentration. To avoid drug-drug interactions and adverse drug reactions in individuals, therefore, it is important to understand whether UGTs are involved in metabolism of drugs and drug candidates. While most of glucuronides are inactive metabolites, acyl-glucuronides that are formed from compounds with a carboxylic acid group can be highly toxic. Animals such as mice and rats are widely used to predict drug metabolism and drug-induced toxicity in humans. However, there are marked species differences in the expression and function of drug-metabolizing enzymes including UGTs. To overcome the species differences, mice in which certain drug-metabolizing enzymes are humanized have been recently developed. Humanized UGT1 (hUGT1) mice were created in 2010 by crossing Ugt1-null mice with human UGT1 transgenic mice in a C57BL/6 background. hUGT1 mice can be promising tools to predict human drug glucuronidation and acyl-glucuronide-associated toxicity. In this review article, studies of drug metabolism and toxicity in the hUGT1 mice are summarized. We further discuss research and strategic directions to advance the understanding of drug glucuronidation in humans. Copyright © 2017 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  5. Free Radical Mechanisms of Xenobiotic Mammalian Cytotoxicities

    DTIC Science & Technology

    1991-06-30

    injury process was mediated through biotransformation of the halocarbons to a free radical intermediate, similar to what happens in the liver . However...peroxidation) of antioxidant agents - is not limited to the liver , but also occurs in vascular cells as well. Unlike the liver , where most of the injury is...frequent mechanism of xenobiotic liver toxicity is biotransformation by cytochrome P,5o-enzymes to toxic free radical intermediates. The primary objective

  6. Free Radical Mechanisms of Xenobiotic Mammalian Cytotoxicities

    DTIC Science & Technology

    1988-10-31

    cytochrome P450 is small compared to that of the liver (about 0.1%), cardiovascular tissues may be more susceptible to oxidative injury because of the... injury participates in the pathogenic mechanisms of many lipophilic xenobiotic compounds). The most dramatic finding is our demonstration that five...UPID PEROXIDATION BETTER THAN THE INITIAL RADICAL OR HYDROPEROXIDE. INDIRECT IRP EFFECTS ON FREE RADICAL MEMBRANE INJURY : 4) POISONING OF THE ELECTRON

  7. Virtual Screening as a Strategy for the Identification of Xenobiotics Disrupting Corticosteroid Action

    PubMed Central

    Praxmarer, Lukas; Chantong, Boonrat; Cereghetti, Diego; Winiger, Rahel; Schuster, Daniela; Odermatt, Alex

    2012-01-01

    Background Impaired corticosteroid action caused by genetic and environmental influence, including exposure to hazardous xenobiotics, contributes to the development and progression of metabolic diseases, cardiovascular complications and immune disorders. Novel strategies are thus needed for identifying xenobiotics that interfere with corticosteroid homeostasis. 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2) and mineralocorticoid receptors (MR) are major regulators of corticosteroid action. 11β-HSD2 converts the active glucocorticoid cortisol to the inactive cortisone and protects MR from activation by glucocorticoids. 11β-HSD2 has also an essential role in the placenta to protect the fetus from high maternal cortisol concentrations. Methods and Principal Findings We employed a previously constructed 3D-structural library of chemicals with proven and suspected endocrine disrupting effects for virtual screening using a chemical feature-based 11β-HSD pharmacophore. We tested several in silico predicted chemicals in a 11β-HSD2 bioassay. The identified antibiotic lasalocid and the silane-coupling agent AB110873 were found to concentration-dependently inhibit 11β-HSD2. Moreover, the silane AB110873 was shown to activate MR and stimulate mitochondrial ROS generation and the production of the proinflammatory cytokine interleukin-6 (IL-6). Finally, we constructed a MR pharmacophore, which successfully identified the silane AB110873. Conclusions Screening of virtual chemical structure libraries can facilitate the identification of xenobiotics inhibiting 11β-HSD2 and/or activating MR. Lasalocid and AB110873 belong to new classes of 11β-HSD2 inhibitors. The silane AB110873 represents to the best of our knowledge the first industrial chemical shown to activate MR. Furthermore, the MR pharmacophore can now be used for future screening purposes. PMID:23056542

  8. 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).

  9. In silico platform for xenobiotics ADME-T pharmacological properties modeling and prediction. Part II: The body in a Hilbertian space.

    PubMed

    Jacob, Alexandre; Pratuangdejkul, Jaturong; Buffet, Sébastien; Launay, Jean-Marie; Manivet, Philippe

    2009-04-01

    We have broken old surviving dogmas and concepts used in computational chemistry and created an efficient in silico ADME-T pharmacological properties modeling and prediction toolbox for any xenobiotic. With the help of an innovative and pragmatic approach combining various in silico techniques, like molecular modeling, quantum chemistry and in-house developed algorithms, the interactions between drugs and those enzymes, transporters and receptors involved in their biotransformation can be studied. ADME-T pharmacological parameters can then be predicted after in vitro and in vivo validations of in silico models.

  10. Development of an ATP measurement method suitable for xenobiotic treatment activated sludge biomass.

    PubMed

    Nguyen, Lan Huong; Chong, Nyuk-Min

    2015-09-01

    Activated sludge consumes a large amount of energy to degrade a xenobiotic organic compound. By tracking the energy inventory of activated sludge biomass during the sludge's degradation of a xenobiotic, any disadvantageous effect on the sludge's performance caused by energy deficiency can be observed. The purpose of this study was to develop a reliable and accurate method for measuring the ATP contents of activated sludge cells that were to degrade a xenobiotic organic. Cell disruption and cellular ATP extraction were performed by a protocol with which xenobiotic degrading activated sludge biomass was washed with SDS, treated by Tris and TCA, and followed by bead blasting. The suspension of disrupted cells was filtered before the filtrate was injected into HPLC that was set at optimal conditions to measure the ATP concentration therein. This extraction protocol and HPLC measurement of ATP was evaluated for its linearity, limits of detection, and reproducibility. Evaluation test results reported a R(2) of 0.999 of linear fit of ATP concentration versus activated sludge concentration, a LOD=0.00045mg/L, a LOQ=0.0015mg/L for HPLC measurement of ATP, a MDL=0.46mg/g SS for ATP extraction protocol, and a recovery efficiency of 96.4±2%. This method of ATP measurement was simple, rapid, reliable, and was unburdened of some limitations other methods may have. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Drugs in hair. Part I. Metabolisms of major drug classes.

    PubMed

    White, R M

    2017-01-01

    Currently, hair can be reliably tested for the presence of drugs. However, one major drawback to the use of parent drugs is the question of potential external or environmental contamination. The analysis of metabolites to confirm the use of the parent drugs was proposed in this short review. The development of hair as a test matrix and the incorporation of xenobiotics, in general, into the hair matrix were discussed. What constitutes an appropriate metabolite for drug testing to mirror the use of a parent drug was proposed and discussed. The use of metabolites rather than parent drugs to indicate unequivocal use rather than external exposure was also discussed for amphetamines, cannabinoids, cocaine, opiates (codeine, morphine, 6-acetylmorphine, hydrocodone, hydromorphone, oxycodone, oxymorphone), phencyclidine, fentanyl, benzodiazepines, and ethanol. This, however, was discussed in terms of class and/or individual drug. In addition, selection or potential selection of appropriate metabolites was reviewed. The actual incorporation of drug metabolites into hair versus the metabolism of drugs which was incorporated into hair were also considered. Copyright © 2017 Central Police University.

  12. The Chemically Inducible Plant Cytochrome P450 CYP76B1 Actively Metabolizes Phenylureas and Other Xenobiotics1

    PubMed Central

    Robineau, Tiburce; Batard, Yannick; Nedelkina, Svetlana; Cabello-Hurtado, Francisco; LeRet, Monique; Sorokine, Odile; Didierjean, Luc; Werck-Reichhart, Danièle

    1998-01-01

    Cytochrome P450s (P450s) constitute one of the major classes of enzymes that are responsible for detoxification of exogenous molecules both in animals and plants. On the basis of its inducibility by exogenous chemicals, we recently isolated a new plant P450, CYP76B1, from Jerusalem artichoke (Helianthus tuberosus) and showed that it was capable of dealkylating a model xenobiotic compound, 7-ethoxycoumarin. In the present paper we show that CYP76B1 is more strongly induced by foreign compounds than other P450s isolated from the same plant, and metabolizes with high efficiency a wide range of xenobiotics, including alkoxycoumarins, alkoxyresorufins, and several herbicides of the class of phenylureas. CYP76B1 catalyzes the double N-dealkylation of phenylureas with turnover rates comparable to those reported for physiological substrates and produces nonphytotoxic compounds. Potential uses for CYP76B1 thus include control of herbicide tolerance and selectivity, as well as soil and groundwater bioremediation. PMID:9808750

  13. Knockout of cytochrome P450 3A yields new mouse models for understanding xenobiotic metabolism

    PubMed Central

    van Herwaarden, Antonius E.; Wagenaar, Els; van der Kruijssen, Cornelia M.M.; van Waterschoot, Robert A.B.; Smit, Johan W.; Song, Ji-Ying; van der Valk, Martin A.; van Tellingen, Olaf; van der Hoorn, José W.A.; Rosing, Hilde; Beijnen, Jos H.; Schinkel, Alfred H.

    2007-01-01

    Cytochrome P450 3A (CYP3A) enzymes constitute an important detoxification system that contributes to primary metabolism of more than half of all prescribed medications. To investigate the physiological and pharmacological roles of CYP3A, we generated Cyp3a-knockout (Cyp3a–/–) mice lacking all functional Cyp3a genes. Cyp3a–/– mice were viable, fertile, and without marked physiological abnormalities. However, these mice exhibited severely impaired detoxification capacity when exposed to the chemotherapeutic agent docetaxel, displaying higher exposure levels in response to both oral and intravenous administration. These mice also demonstrated increased sensitivity to docetaxel toxicity, suggesting a primary role for Cyp3a in xenobiotic detoxification. To determine the relative importance of intestinal versus hepatic Cyp3a in first-pass metabolism, we generated transgenic Cyp3a–/– mice expressing human CYP3A4 in either the intestine or the liver. Expression of CYP3A4 in the intestine dramatically decreased absorption of docetaxel into the bloodstream, while hepatic expression aided systemic docetaxel clearance. These results suggest that CYP3A expression determines impairment of drug absorption and efficient systemic clearance in a tissue-specific manner. The genetic models used in this study provide powerful tools to further study CYP3A-mediated xenobiotic metabolism, as well as interactions between CYP3A and other detoxification systems. PMID:17975676

  14. Interaction of 2,4-Diaminopyrimidine-Containing Drugs Including Fedratinib and Trimethoprim with Thiamine Transporters.

    PubMed

    Giacomini, Marilyn M; Hao, Jia; Liang, Xiaomin; Chandrasekhar, Jayaraman; Twelves, Jolyn; Whitney, J Andrew; Lepist, Eve-Irene; Ray, Adrian S

    2017-01-01

    Inhibition of thiamine transporters has been proposed as a putative mechanism for the observation of Wernicke's encephalopathy and subsequent termination of clinical development of fedratinib, a Janus kinase inhibitor (JAKi). This study aimed to determine the potential for other JAKi to inhibit thiamine transport using human epithelial colorectal adenocarcinoma (Caco-2) and thiamine transporter (THTR) overexpressing cells and to better elucidate the structural basis for interacting with THTR. Only JAKi containing a 2,4-diaminopyrimidine were observed to inhibit thiamine transporters. Fedratinib inhibited thiamine uptake into Caco-2 cells (IC 50 = 0.940 µM) and THTR-2 (IC 50 = 1.36 µM) and, to a lesser extent, THTR-1 (IC 50 = 7.10 µM) overexpressing cells. Two other JAKi containing this moiety, AZD1480 and cerdulatinib, were weaker inhibitors of the thiamine transporters. Other JAKi-including monoaminopyrimidines, such as momelotinib, and nonaminopyrimidines, such as filgotinib-did not have any inhibitory effects on thiamine transport. A pharmacophore model derived from the minimized structure of thiamine suggests that 2,4-diaminopyrimidine-containing compounds can adopt a conformation matching several key features of thiamine. Further studies with drugs containing a 2,4-diaminopyrimidine resulted in the discovery that the antibiotic trimethoprim also potently inhibits thiamine uptake mediated by THTR-1 (IC 50 = 6.84 µM) and THTR-2 (IC 50 = 5.56 µM). Fedratinib and trimethoprim were also found to be substrates for THTR, a finding with important implications for their disposition in the body. In summary, our results show that not all JAKi have the potential to inhibit thiamine transport and further establish the interaction of these transporters with xenobiotics. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  15. Laboratory procedure for estimating residue dynamics of xenobiotic contaminants in a freshwater food chain

    USGS Publications Warehouse

    Johnson, B. Thomas

    1980-01-01

    A laboratory method of measuring the accumulation, transfer, elimination, and degradation of xenobiotic contaminants is described for organisms in a freshwater food chain (microorganisms, filter-feeder, and fish). A flow-through diluter-system, 14C-labeled contaminants, gas and thin-layer chromatography, autoradiography, and liquid scintillation spectrometry are used in making residue determinations. Accumulation factors and various index values are developed for measuring and estimating potential accumulation of xenobiotic contaminants by aquatic organisms. The laboratory procedure is economical, simple, reproducible, and ecologically relevant.

  16. Drug-Induced Liver Toxicity and Prevention by Herbal Antioxidants: An Overview

    PubMed Central

    Singh, Divya; Cho, William C.; Upadhyay, Ghanshyam

    2016-01-01

    The liver is the center for drug and xenobiotic metabolism, which is influenced most with medication/xenobiotic-mediated toxic activity. Drug-induced hepatotoxicity is common and its actual frequency is hard to determine due to underreporting, difficulties in detection or diagnosis, and incomplete observation of exposure. The death rate is high, up to about 10% for drug-induced liver damage. Endorsed medications represented >50% of instances of intense liver failure in a study from the Acute Liver Failure Study Group of the patients admitted in 17 US healing facilities. Albeit different studies are accessible uncovering the mechanistic aspects of medication prompted hepatotoxicity, we are in the dilemma about the virtual story. The expanding prevalence and effectiveness of Ayurveda and natural products in the treatment of various disorders led the investigators to look into their potential in countering drug-induced liver toxicity. Several natural products have been reported to date to mitigate the drug-induced toxicity. The dietary nature and less adverse reactions of the natural products provide them an extra edge over other candidates of supplementary medication. In this paper, we have discussed the mechanism involved in drug-induced liver toxicity and the potential of herbal antioxidants as supplementary medication. PMID:26858648

  17. Do Candida spp. "read" Nietzsche? Can xenobiotics modulate their aggressiveness? Proposition that chemicals may interfere in their virulence attributes.

    PubMed

    Rosa, Edvaldo Antonio Ribeiro

    2012-01-01

    As well as the host, opportunist Candida spp. enface all sorts of exogenous chemicals, so-called xenobiotics. It is plausible that xenobiotics exert some effects on such microorganisms; among them, the modulation of virulence attributes.

  18. Phase 0 and phase III transport in various organs: combined concept of phases in xenobiotic transport and metabolism.

    PubMed

    Döring, Barbara; Petzinger, Ernst

    2014-08-01

    The historical phasing concept of drug metabolism and elimination was introduced to comprise the two phases of metabolism: phase I metabolism for oxidations, reductions and hydrolyses, and phase II metabolism for synthesis. With this concept, biological membrane barriers obstructing the accessibility of metabolism sites in the cells for drugs were not considered. The concept of two phases was extended to a concept of four phases when drug transporters were detected that guided drugs and drug metabolites in and out of the cells. In particular, water soluble or charged drugs are virtually not able to overcome the phospholipid membrane barrier. Drug transporters belong to two main clusters of transporter families: the solute carrier (SLC) families and the ATP binding cassette (ABC) carriers. The ABC transporters comprise seven families with about 20 carriers involved in drug transport. All of them operate as pumps at the expense of ATP splitting. Embedded in the former phase concept, the term "phase III" was introduced by Ishikawa in 1992 for drug export by ABC efflux pumps. SLC comprise 52 families, from which many carriers are drug uptake transporters. Later on, this uptake process was referred to as the "phase 0 transport" of drugs. Transporters for xenobiotics in man and animal are most expressed in liver, but they are also present in extra-hepatic tissues such as in the kidney, the adrenal gland and lung. This review deals with the function of drug carriers in various organs and their impact on drug metabolism and elimination.

  19. Purification and characterization of akr1b10 from human liver: role in carbonyl reduction of xenobiotics.

    PubMed

    Martin, Hans-Jörg; Breyer-Pfaff, Ursula; Wsol, Vladimir; Venz, Simone; Block, Simone; Maser, Edmund

    2006-03-01

    Members of the aldo-keto reductase (AKR) superfamily have a broad substrate specificity in catalyzing the reduction of carbonyl group-containing xenobiotics. In the present investigation, a member of the aldose reductase subfamily, AKR1B10, was purified from human liver cytosol. This is the first time AKR1B10 has been purified in its native form. AKR1B10 showed a molecular mass of 35 kDa upon gel filtration and SDS-polyacrylamide gel electrophoresis. Kinetic parameters for the NADPH-dependent reduction of the antiemetic 5-HT3 receptor antagonist dolasetron, the antitumor drugs daunorubicin and oracin, and the carcinogen 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) to the corresponding alcohols have been determined by HPLC. Km values ranged between 0.06 mM for dolasetron and 1.1 mM for daunorubicin. Enzymatic efficiencies calculated as kcat/Km were more than 100 mM-1 min-1 for dolasetron and 1.3, 0.43, and 0.47 mM-1 min-1 for daunorubicin, oracin, and NNK, respectively. Thus, AKR1B10 is one of the most significant reductases in the activation of dolasetron. In addition to its reducing activity, AKR1B10 catalyzed the NADP+-dependent oxidation of the secondary alcohol (S)-1-indanol to 1-indanone with high enzymatic efficiency (kcat/Km=112 mM-1 min-1). The gene encoding AKR1B10 was cloned from a human liver cDNA library and the recombinant enzyme was purified. Kinetic studies revealed lower activity of the recombinant compared with the native form. Immunoblot studies indicated large interindividual variations in the expression of AKR1B10 in human liver. Since carbonyl reduction of xenobiotics often leads to their inactivation, AKR1B10 may play a role in the occurrence of chemoresistance of tumors toward carbonyl group-bearing cytostatic drugs.

  20. Disposition of xenobiotic chemicals and metabolites in marine organisms.

    PubMed Central

    Varanasi, U; Stein, J E

    1991-01-01

    Studies with several bottom fish species from urban waterways show that of the identified xenobiotic chemicals in bottom sediments, polycylic aromatic hydrocarbons (PAHs) are the most strongly associated with the prevalence of liver lesions, including neoplasms. Accordingly, there is concern about the transfer of contaminants, such as PAHs, from aquatic species to humans. Because PAHs exert their toxicity only after being biotransformed, increasing attention has been focused on the ability of aquatic organisms to metabolize these chemicals. Overall, the results of both laboratory and field studies show that generally low levels (nanograms per gram wet weight) of a few low molecular weight PAHs may be present in edible tissue of fish from contaminated areas and that high molecular weight PAHs, such as the carcinogen benzo(a)pyrene, will rarely be detected because of extensive metabolism. Additionally, the results from a few studies suggest that even though interactions between xenobiotics can affect both biochemical and physiological systems to alter the disposition of PAHs in fish, these interactions do not markedly change the relative proportions of metabolites to parent PAH in tissues. Thus, these studies clearly demonstrate that to obtain some insight into the questions of whether there is any risk to human health from consuming fish and crustaceans from urban areas, techniques must be developed that measure metabolites of carcinogens, such as PAHs, in edible tissue. Initial attempts may focus on semiquantitative methods that permit rapid assessment of the level of metabolites in edible tissues of fish and crustaceans from many urban areas.(ABSTRACT TRUNCATED AT 250 WORDS) Images FIGURE 4. FIGURE 4. FIGURE 4. PMID:2050086

  1. Interaction of xenobiotics on the glucose-transport system and the Na+/K(+)-ATPase of human skin fibroblasts.

    PubMed

    Cascorbi, I; Forêt, M

    1991-02-01

    The effects of individual and combined xenobiotics on functional properties of the plasma membrane of human skin fibroblasts were investigated. Good correlations between toxic effects on the D-glucose transport system or the Na+/K(+)-ATPase and the lipophilicity of the substances could be observed. The linear regression coefficients plotting log EC20 values (doses, leading to 20% inhibition) versus log Pow (octanol/water partition coefficient) were r = 0.95 (P less than 0.05). The combination of lipophilic with less lipophilic xenobiotics, such as pentachlorophenol with 4-chloroaniline, leads to additional effects. However, when the detergent sodium dodecyl benzenesulfonate was combined with the herbicide 2,4-dichlorophenoxyacetate (2,4-D), the toxic effect of 2,4-D on the Na+/K(+)-ATPase decreased considerably. The results support in general the assumption that the inhibition of integral functional proteins is based on an accumulation of xenobiotics in the plasma membrane, probably due to the enhanced membrane fluidity. Thus, the basic toxicity of xenobiotics can be predicted by their physicochemical properties.

  2. Tracing the evolution of degraders in activated sludge during the sludge’s acclimation to a xenobiotic organic

    NASA Astrophysics Data System (ADS)

    Chong, N. M.; Fan, C. H.; Yang, Y. C.

    2017-01-01

    The molecular biology method of high-throughput pyrosequencing was employed to examine the change of activated sludge community structures during the process in which activated sludge was acclimated to and degraded a target xenobiotic. The sample xenobiotic organic compound used as the activated sludge acclimation target was the herbicide 2,4-dichlorphenoxyacetic acid (2,4-D). Indigenous activated sludge microorganisms were acclimated to 2,4-D as the sole carbon source in both the batch and the continuous-flow reaction modes. Sludge masses at multiple time points during the course of acclimation were subjected to pyrosequencing targeting the microorganisms’ 16S rRNA genes. With the bacterial 16S rRNA sequencing results the genera that increased in abundance were checked with degradative pathway databases or literature to confirm that they are commonly seen as potent degraders of 2,4-D. From this systematic examination of degrader changes at time points during activated sludge acclimation and degradation of the target xenobiotic, the trend of degrader evolution in activated sludge over the sludge’s acclimation process to a xenobiotic was traced.

  3. Live-cell imaging approaches for the investigation of xenobiotic-induced oxidant stress.

    PubMed

    Wages, Phillip A; Cheng, Wan-Yun; Gibbs-Flournoy, Eugene; Samet, James M

    2016-12-01

    Oxidant stress is arguably a universal feature in toxicology. Research studies on the role of oxidant stress induced by xenobiotic exposures have typically relied on the identification of damaged biomolecules using a variety of conventional biochemical and molecular techniques. However, there is increasing evidence that low-level exposure to a variety of toxicants dysregulates cellular physiology by interfering with redox-dependent processes. The study of events involved in redox toxicology requires methodology capable of detecting transient modifications at relatively low signal strength. This article reviews the advantages of live-cell imaging for redox toxicology studies. Toxicological studies with xenobiotics of supra-physiological reactivity require careful consideration when using fluorogenic sensors in order to avoid potential artifacts and false negatives. Fortunately, experiments conducted for the purpose of validating the use of these sensors in toxicological applications often yield unexpected insights into the mechanisms through which xenobiotic exposure induces oxidant stress. Live-cell imaging using a new generation of small molecule and genetically encoded fluorophores with excellent sensitivity and specificity affords unprecedented spatiotemporal resolution that is optimal for redox toxicology studies. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu. Published by Elsevier B.V.

  4. Marine Invertebrate Xenobiotic-Activated Nuclear Receptors: Their Application as Sensor Elements in High-Throughput Bioassays for Marine Bioactive Compounds

    PubMed Central

    Richter, Ingrid; Fidler, Andrew E.

    2014-01-01

    Developing high-throughput assays to screen marine extracts for bioactive compounds presents both conceptual and technical challenges. One major challenge is to develop assays that have well-grounded ecological and evolutionary rationales. In this review we propose that a specific group of ligand-activated transcription factors are particularly well-suited to act as sensors in such bioassays. More specifically, xenobiotic-activated nuclear receptors (XANRs) regulate transcription of genes involved in xenobiotic detoxification. XANR ligand-binding domains (LBDs) may adaptively evolve to bind those bioactive, and potentially toxic, compounds to which organisms are normally exposed to through their specific diets. A brief overview of the function and taxonomic distribution of both vertebrate and invertebrate XANRs is first provided. Proof-of-concept experiments are then described which confirm that a filter-feeding marine invertebrate XANR LBD is activated by marine bioactive compounds. We speculate that increasing access to marine invertebrate genome sequence data, in combination with the expression of functional recombinant marine invertebrate XANR LBDs, will facilitate the generation of high-throughput bioassays/biosensors of widely differing specificities, but all based on activation of XANR LBDs. Such assays may find application in screening marine extracts for bioactive compounds that could act as drug lead compounds. PMID:25421319

  5. Cytochrome P450 humanised mice

    PubMed Central

    2004-01-01

    Humans are exposed to countless foreign compounds, typically referred to as xenobiotics. These can include clinically used drugs, environmental pollutants, food additives, pesticides, herbicides and even natural plant compounds. Xenobiotics are metabolised primarily in the liver, but also in the gut and other organs, to derivatives that are more easily eliminated from the body. In some cases, however, a compound is converted to an electrophile that can cause cell toxicity and transformation leading to cancer. Among the most important xenobiotic-metabolising enzymes are the cytochromes P450 (P450s). These enzymes represent a superfamily of multiple forms that exhibit marked species differences in their expression and catalytic activities. To predict how humans will metabolise xenobiotics, including drugs, human liver extracts and recombinant P450s have been used. New humanised mouse models are being developed which will be of great value in the study of drug metabolism, pharmacokinetics and pharmacodynamics in vivo, and in carrying out human risk assessment of xenobiotics. Humanised mice expressing CYP2D6 and CYP3A4, two major drug-metabolising P450s, have revealed the feasibility of this approach. PMID:15588489

  6. EFFECT OF PREGNANE XENOBIOTIC RECEPTOR ACTIVATION ON INFLAMMATORY BOWEL DISEASE TREATED WITH RIFAXIMIN.

    PubMed

    Wan, Y C; Li, T; Han, Y-D; Zhang, H-Y; Lin, H; Zhang, B

    2015-01-01

    The causes and pathogenesis of Inflammatory Bowel Disease (IBD) are still not clearly understood. This study aims to prove the important role of rifaximin played in inflammatory reaction caused by abnormity of the intestinal mucosal immune system. Intestinal microflora can greatly promote and maintain the inflammatory reaction of IBD, therefore, antibiotics can be used to treat IBD. Rifaximin is a medicine usually used for local intestinal infection. Many clinical and basic studies have shown that both a single application of rifaximin and the joint application with other medicines could achieve a good efficacy. This paper studied the activation of Pregnane Xenobiotic Receptor (PXR) in treating IBD with rifaximin and analyzed its efficacy in IBD when PXR was involved in the transport of medicine and metabolism. The results prove that rifaximin can not only serve as an anti-microbial drug, but can activate PXR and actually weaken the reaction of IBD. Thus it is safe to say that rifaximin has great potential in treating IBD.

  7. Disposition of xenobiotic chemicals and metabolites in marine organisms

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Varanasi, U.; Stein, J.E.

    1991-01-01

    Studies with several bottom fish species from urban waterways show that of the identified xenobiotic chemicals in bottom sediments, polycyclic aromatic hydrocarbons (PAHs) are the most strongly associated with the prevalence of liver lesions, including neoplasms. Accordingly, there is concern about the transfer of contaminants, such as PAHs, from aquatic species to humans. Because PAHs exert their toxicity only after being biotransformed, increasing attention has been focused on the ability of aquatic organisms to metabolize these chemicals. Overall, the results of both laboratory and field studies show that generally low levels of a few low molecular weight PAHs may bemore » present in edible tissue of fish from contaminated areas and that high molecular weight PAHs, such as the carcinogen benzo(a)pyrene, will rarely be detected because of extensive metabolism. Additionally, the results from a few studies suggest that even though interactions between xenobiotics can affect both biochemical and physiological systems to alter the disposition of PAHs in fish, these interactions do not markedly change the relative proportions of metabolites to parent PAH in tissues. Thus, these studies clearly demonstrate that to obtain some insight into the questions of whether there is any risk to human health from consuming fish and crustaceans from urban areas, techniques must be developed that measure metabolites of carcinogens, such as PAHs, in edible tissue. Initial attempts may focus on semiquantitative methods that permit rapid assessment of the level of metabolites in edible tissues of fish and crustaceans from many urban areas. Based on information from such screening studies, further refinement in methodology leading to identification of specific compounds may be needed because certain metabolites may not be as toxic or carcinogenic as others.« less

  8. Structure-activity relationships for xenobiotic transport substrates and inhibitory ligands of P-glycoprotein.

    PubMed Central

    Bain, L J; McLachlan, J B; LeBlanc, G A

    1997-01-01

    The multixenobiotic resistance phenotype is characterized by the reduced accumulation of xenobiotics by cells or organisms due to increased efflux of the compounds by P-glycoprotein (P-gp) or related transporters. An extensive xenobiotic database, consisting primarily of pesticides, was utilized in this study to identify molecular characteristics that render a xenobiotic susceptible to transport by or inhibition of P-gp. Transport substrates were differentiated by several molecular size/shape parameters, lipophilicity, and hydrogen bonding potential. Electrostatic features differentiated inhibitory ligands from compounds not catagorized as transport substrates and that did no interact with P-gp. A two-tiered system was developed using the derived structure-activity relationships to identify P-gp transport substrates and inhibitory ligands. Prediction accuracy of the approach was 82%. We then validated the system using six additional pesticides of which tow were predicted to be P-gp inhibitors and four were predicted to be noninteractors, based upon the structure-activity analyses. Experimental determinations using cells transfected with the human MDR1 gene demonstrated that five of the six pesticides were properly catagorized by the structure-activity analyses (83% accuracy). Finally, structure-activity analyses revealed that among P-gp inhibitors, relative inhibitory potency can be predicted based upon the surface area or volume of the compound. These results demonstrate that P-gp transport substrates and inhibitory ligands can be distinguished using molecular characteristics. Molecular characteristics of transport substrates suggest that P-gp may function in the elimination of hydroxylated metabolites of xenobiotics. Images Figure 1. A Figure 1. B Figure 1. C Figure 1. D Figure 1. E Figure 1. F Figure 1. G Figure 1. H Figure 2. Figure 2. Figure 2. Figure 2. Figure 2. Figure 2. Figure 3. A Figure 3. B PMID:9347896

  9. GENE EXPRESSION PROFILING OF XENOBIOTIC METABOLIZING ENZYMES (XMES) THROUGH THE LIFE STAGES OF THE MALE C57BL/6 MOUSE

    EPA Science Inventory

    In the presence of foreign compounds, metabolic homeostasis of the organism is maintained by the liver's ability to detoxify and eliminate these xenobiotics. This is accomplished, in part, by the expression of XMEs, which metabolize xenobiotics and determine whether exposure will...

  10. Daphnia HR96 is a Promiscuous Xenobiotic and Endobiotic Nuclear Receptor

    PubMed Central

    Karimullina, Elina; Li, Yangchun; Ginjupalli, Gautam; Baldwin, William S.

    2012-01-01

    Daphnia pulex is the first crustacean to have its genome sequenced. The genome project provides new insight and data into how an aquatic crustacean may respond to environmental stressors, including toxicants. We cloned Daphnia pulex HR96 (DappuHR96), a nuclear receptor orthologous to the CAR/PXR/VDR group of nuclear receptors. In Drosophila melanogaster, (hormone receptor 96) HR96 responds to phenobarbital exposure and has been hypothesized as a toxicant receptor. Therefore, we set up a transactivation assay to test whether DappuHR96 is a promiscuous receptor activated by xenobiotics and endobiotics similar to the constitutive androstane receptor (CAR) and the pregnane X-receptor (PXR). Transactivation assays performed with a GAL4-HR96 chimera demonstrate that HR96 is a promiscuous toxicant receptor activated by a diverse set of chemicals such as pesticides, hormones, and fatty acids. Several environmental toxicants activate HR96 including estradiol, pyriproxyfen, chlorpyrifos, atrazine, and methane arsonate. We also observed repression of HR96 activity by chemicals such as triclosan, androstanol, and fluoxetine. Nearly 50% of the chemicals tested activated or inhibited HR96. Interestingly, unsaturated fatty acids were common activators or inhibitors of HR96 activity, indicating a link between diet and toxicant response. The omega-6 and omega-9 unsaturated fatty acids linoleic and oleic acid activated HR96, but the omega-3 unsaturated fatty acids alpha-linolenic acid and docosahexaenoic acid inhibited HR96, suggesting that these two distinct sets of lipids perform opposing roles in Daphnia physiology. This also provides a putative mechanism by which the ratio of dietary unsaturated fats may affect the ability of an organism to respond to a toxic insult. In summary, HR96 is a promiscuous nuclear receptor activated by numerous endo- and xenobiotics. PMID:22466357

  11. An in vitro bioassay for xenobiotics using the SXR-driven human CYP3A4/lacZ reporter gene.

    PubMed

    Lee, Mi R; Kim, Yeon J; Hwang, Dae Y; Kang, Tae S; Hwang, Jin H; Lim, Chae H; Kang, Hyung K; Goo, Jun S; Lim, Hwa J; Ahn, Kwang S; Cho, Jung S; Chae, Kap R; Kim, Yong K

    2003-01-01

    The dose and time effect of nine xenobiotics, including 17beta-estradiol, corticosterone, dexamethasone, progesterone, nifedipine, bisphenol A, rifampicin, methamphetamine, and nicotine were investigated, in vitro, using human steroid and xenobiotics receptor (SXR)-binding sites on the human CYP3A4 promoter, which can enhance the linked lacZ reporter gene transcription. To test this, liver-specific SAP (human serum amyloid P component)-SXR (SAP/SXR) and human CYP3A4 promoter-regulated lacZ (hCYP3A4/lacZ) constructs were transiently transfected into HepG2 and NIH3T3 cells to compare the xenobiotic responsiveness between human and nonhuman cell lines. In the HepG2 cells, rifampicin, followed by corticosterone, nicotine, methamphetamine, and dexamethasone, exhibited enhanced levels of the lacZ transcript, whereas those of bisphenol A and nifedipine were found to be reduced. No significant responses were observed with 17beta-estradiol or progesterone. In addition, 17beta-estradiol and progesterone did not change the levels of the lacZ transcripts in the HepG2 cells, but did induce significant increases in the transcripts of the NIH3T3 cells. Treatment with corticosterone and dexamethasone, which were highly expressed in the HepG2 cells, did not affect the levels of the lacZ transcript in NIH3T3 cells. These results show that lacZ transcripts can be measured, rapidly and reproducibly, using reverse transcriptase-polymerase chain reaction (RT-PCR) based on the expression of the hCYP3A4/lacZ reporter gene, and was mediated by the SXR. Thus, this in vitro reporter gene bioassay is useful for measuring xenobiotic activities, and is a means to a better relevant bioassay, using human cells, human genes and human promoters, in order to get a closer look at actual human exposure.

  12. Effects of frying oil and Houttuynia cordata thunb on xenobiotic-metabolizing enzyme system of rodents

    PubMed Central

    Chen, Ya-Yen; Chen, Chiao-Ming; Chao, Pi-Yu; Chang, Tsan-Ju; Liu, Jen-Fang

    2005-01-01

    AIM: To evaluate the effects of frying oil and Houttuynia cordata Thunb (H. cordata), a vegetable traditionally consumed in Taiwan, on the xenobiotic-metabolizing enzyme system of rodents. METHODS: Forty-eight Sprague-Dawley rats were fed with a diet containing 0%, 2% or 5% H. cordata powder and 15% fresh soybean oil or 24-h oxidized frying oil (OFO) for 28 d respectively. The level of microsomal protein, total cytochrome 450 content (CYP450) and enzyme activities including NADPH reductase, ethoxyresorufin O-deethylase (EROD), pentoxyresorufin O-dealkylase (PROD), aniline hydroxylase (ANH), aminopyrine demethylase (AMD), and quinone reductase (QR) were determined. QR represented phase II enzymes, the rest of the enzymes tested represented phase I enzymes. RESULTS: The oxidized frying oil feeding produced a significant increase in phase I and II enzyme systems, including the content of CYP450 and microsomal protein, and the activities of NADPH reductase, EROD, PROD, ANH, AMD and QR in rats (P<0.05). In addition, the activities of EROD, ANH and AMD decreased and QR increased after feeding with H. cordata in OFO-fed group (P<0.05). The feeding with 2% H. cordata diet showed the most significant effect. CONCLUSION: The OFO diet induces phases I and II enzyme activity, and the 2% H. cordata diet resulted in a better regulation of the xenobiotic-metabolizing enzyme system. PMID:15637750

  13. Potential for drug interactions mediated by polymorphic flavin-containing monooxygenase 3 in human livers.

    PubMed

    Shimizu, Makiko; Shiraishi, Arisa; Sato, Ayumi; Nagashima, Satomi; Yamazaki, Hiroshi

    2015-02-01

    Human flavin-containing monooxygenase 3 (FMO3) in the liver catalyzes a variety of oxygenations of nitrogen- and sulfur-containing medicines and xenobiotic substances. Because of growing interest in drug interactions mediated by polymorphic FMO3, benzydamine N-oxygenation by human FMO3 was investigated as a model reaction. Among the 41 compounds tested, trimethylamine, methimazole, itopride, and tozasertib (50 μM) suppressed benzydamine N-oxygenation at a substrate concentration of 50 μM by approximately 50% after co-incubation. Suppression of N-oxygenation of benzydamine, trimethylamine, itopride, and tozasertib and S-oxygenation of methimazole and sulindac sulfide after co-incubation with the other five of these six substrates was compared using FMO3 proteins recombinantly expressed in bacterial membranes. Apparent competitive inhibition by methimazole (0-50 μM) of sulindac sulfide S-oxygenation was observed with FMO3 proteins. Sulindac sulfide S-oxygenation activity of Arg205Cys variant FMO3 protein was likely to be suppressed more by methimazole than wild-type or Val257Met variant FMO3 protein was. These results suggest that genetic polymorphism in the human FMO3 gene may lead to changes of drug interactions for N- or S-oxygenations of xenobiotics and endogenous substances and that a probe battery system of benzydamine N-oxygenation and sulindac sulfide S-oxygenation activities is recommended to clarify the drug interactions mediated by FMO3. Copyright © 2014 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  14. Update on nandrolone and norsteroids: how endogenous or xenobiotic are these substances?

    PubMed

    Bricout, V; Wright, F

    2004-06-01

    Norsteroids are xenobiotics with androgenic and anabolic properties known since as far back as the 1930s. In doping controls, the use of the banned xenobiotic norsteroids is detected in the competitor's urines by the measurement of norandrosterone (19-NA) and noretiocholanolone (19-NE), which are the main metabolites for nandrolone (NT) and most norsteroids with anabolic properties. In 1996, the IOC subcommission "Doping and Biochemistry of Sport" informed the Heads of the "IOC Accredited Laboratories" that the recommended cut-off limit for reporting an offence was to be 1-2 ng ml(-1) urine for either 19-NA or 19-NE. We will discuss how technical progress in gas chromatography coupled to high-resolution mass spectrometry permitted a dramatic increase in sensitivity with a detection limit of 1 pg ml(-1) urine, or less, and an assay limit of 20-50 pg ml(-1) urine, for either 19-NA or 19-NE. As a paradox, norsteroids have been known for decades as not only xenobiotics but also obligatory endogenous intermediates in the biosynthesis of estrogens from androgens in all species, man included. It is this biochemical observation which fed the active scientific and medical controversy initiated in 1998 over the possibly endogenous production of nandrolone and metabolites well over the new IOC's recommended cut-off limit of 2 ng ml(-1) urine. Notwithstanding the particular technical difficulties attached, we will provide data and discuss the minute endogenous levels detected and measured in man either at rest, after performance or training and compare them to the relatively high levels reported in male athlete's doping controls today. We will also discuss data on the pharmacological effects of some contraceptive therapies containing norsteroids in women. In view of the well-documented noxious effects repeatedly observed after anabolic steroid misuse, the confirmation and implementation of technically proven procedures for reporting norsteroid abuse in sports seems an

  15. Human gut microbiota plays a role in the metabolism of drugs.

    PubMed

    Jourova, Lenka; Anzenbacher, Pavel; Anzenbacherova, Eva

    2016-09-01

    The gut microbiome, an aggregate genome of trillions of microorganisms residing in the human gastrointestinal tract, is now known to play a critical role in human health and predisposition to disease. It is also involved in the biotransformation of xenobiotics and several recent studies have shown that the gut microbiota can affect the pharmacokinetics of orally taken drugs with implications for their oral bioavailability. Review of Pubmed, Web of Science and Science Direct databases for the years 1957-2016. Recent studies make it clear that the human gut microbiota can play a major role in the metabolism of xenobiotics and, the stability and oral bioavailability of drugs. Over the past 50 years, more than 30 drugs have been identified as a substrate for intestinal bacteria. Questions concerning the impact of the gut microbiota on drug metabolism, remain unanswered or only partially answered, namely (i) what are the molecular mechanisms and which bacterial species are involved? (ii) What is the impact of host genotype and environmental factors on the composition and function of the gut microbiota, (iii) To what extent is the composition of the intestinal microbiome stable, transmissible, and resilient to perturbation? (iv) Has past exposure to a given drug any impact on future microbial response, and, if so, for how long? Answering such questions should be an integral part of pharmaceutical research and personalised health care.

  16. Coordinated changes in xenobiotic metabolizing enzyme (XME) gene expression through the life stages of the male C57BL/6 mouse

    EPA Science Inventory

    Metabolic homeostasis of the organism is maintained by the liver's ability to detoxify and eliminate xenobiotics. This is accomplished, in part, by the expression of XMEs, which metabolize xenobiotics and determine whether exposure will result in toxicity. Some evidence indicates...

  17. Live-cell Imaging Approaches for the Investigation of Xenobiotic-Induced Oxidant Stress

    EPA Science Inventory

    BACKGROUND: Oxidant stress is arguably a universal feature in toxicology. Research studies on the role of oxidant stress induced by xenobiotic exposures have typically relied on the identification of damaged biomolecules using a variety of conventional biochemical and molecular t...

  18. Retrofit Strategies for Incorporating Xenobiotic Metabolism into High Throughput Screening Assays (EMGS)

    EPA Science Inventory

    The US EPA’s ToxCast program is designed to assess chemical perturbations of molecular and cellular endpoints using a variety of high-throughput screening (HTS) assays. However, existing HTS assays have limited or no xenobiotic metabolism which could lead to a mischaracterization...

  19. A Comprehensive List of Items to be Included on a Pediatric Drug Monograph

    PubMed Central

    Ito, Shinya; Woods, David; Nunn, Anthony J.; Taketomo, Carol; de Hoog, Matthijs; Offringa, Martin

    2017-01-01

    OBJECTIVES Children require special considerations for drug prescribing. Drug information summarized in a formulary containing drug monographs is essential for safe and effective prescribing. Currently, little is known about the information needs of those who prescribe and administer medicines to children. Our primary objective was to identify a list of important and relevant items to be included in a pediatric drug monograph. METHODS Following the establishment of an expert steering committee and an environmental scan of adult and pediatric formulary monograph items, 46 participants from 25 countries were invited to complete a 2-round Delphi survey. Questions regarding source of prescribing information and importance of items were recorded. An international consensus meeting to vote on and finalize the items list with the steering committee followed. RESULTS Pediatric formularies are most commonly the first resource consulted for information on medication used in children by 31 Delphi participants. After the Delphi rounds, 116 items were identified to be included in a comprehensive pediatric drug monograph, including general information, adverse drug reactions, dosages, precautions, drug-drug interactions, formulation, and drug properties. CONCLUSIONS Health care providers identified 116 monograph items as important for prescribing medicines for children by an international consensus-based process. This information will assist in setting standards for the creation of new pediatric drug monographs for international application and for those involved in pediatric formulary development. PMID:28337081

  20. A Comprehensive List of Items to be Included on a Pediatric Drug Monograph.

    PubMed

    Kelly, Lauren E; Ito, Shinya; Woods, David; Nunn, Anthony J; Taketomo, Carol; de Hoog, Matthijs; Offringa, Martin

    2017-01-01

    Children require special considerations for drug prescribing. Drug information summarized in a formulary containing drug monographs is essential for safe and effective prescribing. Currently, little is known about the information needs of those who prescribe and administer medicines to children. Our primary objective was to identify a list of important and relevant items to be included in a pediatric drug monograph. Following the establishment of an expert steering committee and an environmental scan of adult and pediatric formulary monograph items, 46 participants from 25 countries were invited to complete a 2-round Delphi survey. Questions regarding source of prescribing information and importance of items were recorded. An international consensus meeting to vote on and finalize the items list with the steering committee followed. Pediatric formularies are most commonly the first resource consulted for information on medication used in children by 31 Delphi participants. After the Delphi rounds, 116 items were identified to be included in a comprehensive pediatric drug monograph, including general information, adverse drug reactions, dosages, precautions, drug-drug interactions, formulation, and drug properties. Health care providers identified 116 monograph items as important for prescribing medicines for children by an international consensus-based process. This information will assist in setting standards for the creation of new pediatric drug monographs for international application and for those involved in pediatric formulary development.

  1. 21 CFR 1405.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false What must I include in my drug-free workplace... REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 1405.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a...

  2. Live-cell imaging approaches for the investigation of xenobiotic-induced oxidant stress☆,☆☆

    PubMed Central

    Wages, Phillip A.; Cheng, Wan-Yun; Gibbs-Flournoy, Eugene; Samet, James M.

    2017-01-01

    Background Oxidant stress is arguably a universal feature in toxicology. Research studies on the role of oxidant stress induced by xenobiotic exposures have typically relied on the identification of damaged biomolecules using a variety of conventional biochemical and molecular techniques. However, there is increasing evidence that low-level exposure to a variety of toxicants dysregulates cellular physiology by interfering with redox-dependent processes. Scope of review The study of events involved in redox toxicology requires methodology capable of detecting transient modifications at relatively low signal strength. This article reviews the advantages of live-cell imaging for redox toxicology studies. Major conclusions Toxicological studies with xenobiotics of supra-physiological reactivity require careful consideration when using fluorogenic sensors in order to avoid potential artifacts and false negatives. Fortunately, experiments conducted for the purpose of validating the use of these sensors in toxicological applications often yield unexpected insights into the mechanisms through which xenobiotic exposure induces oxidant stress. General significance Live-cell imaging using a new generation of small molecule and genetically encoded fluorophores with excellent sensitivity and specificity affords unprecedented spatiotemporal resolution that is optimal for redox toxicology studies. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu. PMID:27208426

  3. Behavioral responses of honey bees (Apis mellifera) to natural and synthetic xenobiotics in food.

    PubMed

    Liao, Ling-Hsiu; Wu, Wen-Yen; Berenbaum, May R

    2017-11-21

    While the natural foods of the western honey bee (Apis mellifera) contain diverse phytochemicals, in contemporary agroecosystems honey bees also encounter pesticides as floral tissue contaminants. Whereas some ubiquitous phytochemicals in bee foods up-regulate detoxification and immunity genes, thereby benefiting nestmates, many agrochemical pesticides adversely affect bee health even at sublethal levels. How honey bees assess xenobiotic risk to nestmates as they forage is poorly understood. Accordingly, we tested nine phytochemicals ubiquitous in nectar, pollen, or propolis, as well as five synthetic xenobiotics that frequently contaminate hives-two herbicides (atrazine and glyphosate) and three fungicides (boscalid, chlorothalonil, and prochloraz). In semi-field free-flight experiments, bees were offered a choice between paired sugar water feeders amended with either a xenobiotic or solvent only (control). Among the phytochemicals, foragers consistently preferred quercetin at all five concentrations tested, as evidenced by both visitation frequency and consumption rates. This preference may reflect the long evolutionary association between honey bees and floral tissues. Of pesticides eliciting a response, bees displayed a preference at specific concentrations for glyphosate and chlorothalonil. This paradoxical preference may account for the frequency with which these pesticides occur as hive contaminants and suggests that they present a greater risk factor for honey bee health than previously suspected.

  4. Avian species differences in the intestinal absorption of xenobiotics (PCB, dieldrin, Hg2+)

    USGS Publications Warehouse

    Serafin, J.A.

    1984-01-01

    1. Intestinal absorption of a polychlorinated biphenyl, dieldrin, and mercury (from HgCl2) was measured in adult Northern bobwhites, Eastern screech owls, American kestrels, black-crowned night-herons and mallards in vivo by an in situ luminal perfusion technique.2. Bobwhites, screech owls and kestrels absorbed much more of each xenobiotic than black-crowned night-herons and mallards.3. Mallards absorbed less dieldrin and mercury than black-crowned night-herons.4. Mercury absorption by kestrels was more than twice that in screech owls and eight times that observed in mallards.5. Pronounced differences in xenobiotic absorption rates between bobwhites, screech owls and kestrels on the one hand, and black-crowned night-herons and mallards on the other, raise the possibility that absorptive ability may be associated with the phylogenetic classification of birds.

  5. Glutathione S-conjugates as prodrugs to target drug-resistant tumors

    PubMed Central

    Ramsay, Emma E.; Dilda, Pierre J.

    2014-01-01

    Living organisms are continuously exposed to xenobiotics. The major phase of enzymatic detoxification in many species is the conjugation of activated xenobiotics to reduced glutathione (GSH) catalyzed by the glutathione-S-transferase (GST). It has been reported that some compounds, once transformed into glutathione S-conjugates, enter the mercapturic acid pathway whose end products are highly reactive and toxic for the cell responsible for their production. The cytotoxicity of these GSH conjugates depends essentially on GST and gamma-glutamyl transferases (γGT), the enzymes which initiate the mercapturic acid synthesis pathway. Numerous studies support the view that the expression of GST and γGT in cancer cells represents an important factor in the appearance of a more aggressive and resistant phenotype. High levels of tumor GST and γGT expression were employed to selectively target tumor with GST- or γGT-activated drugs. This strategy, explored over the last two decades, has recently been successful using GST-activated nitrogen mustard (TLK286) and γGT-activated arsenic-based (GSAO and Darinaparsin) prodrugs confirming the potential of GSH-conjugates as anticancer drugs. PMID:25157234

  6. [Hypothetical link between endometriosis and xenobiotics-associated genetically modified food].

    PubMed

    Aris, A; Paris, K

    2010-12-01

    Endometriosis is an oestrogen-dependent inflammatory disease affecting 10 % of reproductive-aged women. Often accompanied by chronic pelvic pain and infertility, endometriosis rigorously interferes with women's quality of life. Although the pathophysiology of endometriosis remains unclear, a growing body of evidence points to the implication of environmental toxicants. Over the last decade, an increase in the incidence of endometriosis has been reported and coincides with the introduction of genetically modified foods in our diet. Even though assessments of genetically modified food risk have not indicated any hazard on human health, xenobiotics-associated genetically modified food, such as pesticides residues and xenoproteins, could be harmful in the long-term. The "low-dose hypothesis", accumulation and biotransformation of pesticides-associated genetically modified food and the multiplied toxicity of pesticides-formulation adjuvants support this hypothesis. This review summarizes toxic effects (in vitro and on animal models) of some xenobiotics-associated genetically modified food, such as glyphosate and Cry1Ab protein, and extrapolates on their potential role in the pathophysiology of endometriosis. Their roles as immune toxicants, pro-oxidants, endocrine disruptors and epigenetic modulators are discussed. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  7. ABC multidrug transporters: target for modulation of drug pharmacokinetics and drug-drug interactions.

    PubMed

    Marquez, Béatrice; Van Bambeke, Françoise

    2011-05-01

    Nine proteins of the ABC superfamily (P-glycoprotein, 7 MRPs and BCRP) are involved in multidrug transport. Being localised at the surface of endothelial or epithelial cells, they expel drugs back to the external medium (if located at the apical side [P-glycoprotein, BCRP, MRP2, MRP4 in the kidney]) or to the blood (if located at the basolateral side [MRP1, MRP3, MRP4, MRP5]), modulating thereby their absorption, distribution, and elimination. In the CNS, most transporters are oriented to expel drugs to the blood. Transporters also cooperate with Phase I/Phase II metabolism enzymes by eliminating drug metabolites. Their major features are (i) their capacity to recognize drugs belonging to unrelated pharmacological classes, and (ii) their redundancy, a single molecule being possibly substrate for different transporters. This ensures an efficient protection of the body against invasion by xenobiotics. Competition for transport is now characterized as a mechanism of interaction between co-administered drugs, one molecule limiting the transport of the other, potentially affecting bioavailability, distribution, and/or elimination. Again, this mechanism reinforces drug interactions mediated by cytochrome P450 inhibition, as many substrates of P-glycoprotein and CYP3A4 are common. Induction of the expression of genes coding for MDR transporters is another mechanism of drug interaction, which could affect all drug substrates of the up-regulated transporter. Overexpression of MDR transporters confers resistance to anticancer agents and other therapies. All together, these data justify why studying drug active transport should be part of the evaluation of new drugs, as recently recommended by the FDA.

  8. Correlation of the lipophilicity of xenobiotics with their synergistic effects on DNA synthesis in human fibroblasts.

    PubMed

    Jacobi, H; Leier, G; Witte, I

    1996-04-01

    The binary combination effects of DNA synthesis of human fibroblasts were investigated using 2,4-D with 15 xenobiotics of different chemical substance classes. Results were compared with previous investigations on cell growth. Each of the 15 chemicals tested at their no effect concentrations (NOEC's) increased the effects of 2,4-D on DNA synthesis. Thereby, the EC20 value of 2,4-D was reduced by approximately 40% in the combinations. The NOEC's of the xenobiotics used in the combinations varied by a factor of 1,600 and depended strongly on the lipophilicity of the agents combined with 2,4-D. A significant statistical correlation of r = 0.90 was found between the NOEC's of the 15 combined xenobiotics and their lipophilicity. The combination effects on DNA synthesis were similar to those on cell growth. The regression lines of the relationship between the NOEC's and lipophilicity in both assays showed only slight differences in the slopes. This is an additional confirmation of our hypothesis on a facilitated uptake of 2,4-D in the binary combinations.

  9. Acetaminophen induces xenobiotic-metabolizing enzymes in rat: Impact of a uranium chronic exposure.

    PubMed

    Rouas, Caroline; Souidi, Maâmar; Grandcolas, Line; Grison, Stephane; Baudelin, Cedric; Gourmelon, Patrick; Pallardy, Marc; Gueguen, Yann

    2009-11-01

    The extensive use of uranium in civilian and military applications increases the risk of human chronic exposure. Uranium is a slightly radioactive heavy metal with a predominantly chemical toxicity, especially in kidney but also in liver. Few studies have previously shown some effects of uranium on xenobiotic-metabolizing enzymes (XME) that might disturb drug pharmacokinetic. The aim of this study was to determine whether a chronic (9 months) non-nephrotoxic low dose exposure to depleted uranium (DU, 1mg/rat/day) could modify the liver XME, using a single non-hepatotoxic acetaminophen (APAP) treatment (50mg/kg). Most of XME analysed were induced by APAP treatment at the gene expression level but at the protein level only CYP3A2 was significantly increased 3h after APAP treatment in DU-exposed rats whereas it remained at a basal level in unexposed rats. In conclusion, these results showed that a chronic non-nephrotoxic DU exposure specially modify CYP3A2 after a single therapeutic APAP treatment. Copyright © 2009 Elsevier B.V. All rights reserved.

  10. High-throughput metagenomic analysis of petroleum-contaminated soil microbiome reveals the versatility in xenobiotic aromatics metabolism.

    PubMed

    Bao, Yun-Juan; Xu, Zixiang; Li, Yang; Yao, Zhi; Sun, Jibin; Song, Hui

    2017-06-01

    The soil with petroleum contamination is one of the most studied soil ecosystems due to its rich microorganisms for hydrocarbon degradation and broad applications in bioremediation. However, our understanding of the genomic properties and functional traits of the soil microbiome is limited. In this study, we used high-throughput metagenomic sequencing to comprehensively study the microbial community from petroleum-contaminated soils near Tianjin Dagang oilfield in eastern China. The analysis reveals that the soil metagenome is characterized by high level of community diversity and metabolic versatility. The metageome community is predominated by γ-Proteobacteria and α-Proteobacteria, which are key players for petroleum hydrocarbon degradation. The functional study demonstrates over-represented enzyme groups and pathways involved in degradation of a broad set of xenobiotic aromatic compounds, including toluene, xylene, chlorobenzoate, aminobenzoate, DDT, methylnaphthalene, and bisphenol. A composite metabolic network is proposed for the identified pathways, thus consolidating our identification of the pathways. The overall data demonstrated the great potential of the studied soil microbiome in the xenobiotic aromatics degradation. The results not only establish a rich reservoir for novel enzyme discovery but also provide putative applications in bioremediation. Copyright © 2016. Published by Elsevier B.V.

  11. Gut Pharmacomicrobiomics: the tip of an iceberg of complex interactions between drugs and gut-associated microbes.

    PubMed

    Saad, Rama; Rizkallah, Mariam R; Aziz, Ramy K

    2012-11-30

    The influence of resident gut microbes on xenobiotic metabolism has been investigated at different levels throughout the past five decades. However, with the advance in sequencing and pyrotagging technologies, addressing the influence of microbes on xenobiotics had to evolve from assessing direct metabolic effects on toxins and botanicals by conventional culture-based techniques to elucidating the role of community composition on drugs metabolic profiles through DNA sequence-based phylogeny and metagenomics. Following the completion of the Human Genome Project, the rapid, substantial growth of the Human Microbiome Project (HMP) opens new horizons for studying how microbiome compositional and functional variations affect drug action, fate, and toxicity (pharmacomicrobiomics), notably in the human gut. The HMP continues to characterize the microbial communities associated with the human gut, determine whether there is a common gut microbiome profile shared among healthy humans, and investigate the effect of its alterations on health. Here, we offer a glimpse into the known effects of the gut microbiota on xenobiotic metabolism, with emphasis on cases where microbiome variations lead to different therapeutic outcomes. We discuss a few examples representing how the microbiome interacts with human metabolic enzymes in the liver and intestine. In addition, we attempt to envisage a roadmap for the future implications of the HMP on therapeutics and personalized medicine.

  12. 45 CFR 630.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false What must I include in my drug-free workplace...) NATIONAL SCIENCE FOUNDATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 630.205 What must I include in my drug-free workplace...

  13. 45 CFR 630.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 3 2011-10-01 2011-10-01 false What must I include in my drug-free workplace...) NATIONAL SCIENCE FOUNDATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 630.205 What must I include in my drug-free workplace...

  14. 45 CFR 630.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 3 2013-10-01 2013-10-01 false What must I include in my drug-free workplace...) NATIONAL SCIENCE FOUNDATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 630.205 What must I include in my drug-free workplace...

  15. 45 CFR 630.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 3 2014-10-01 2014-10-01 false What must I include in my drug-free workplace...) NATIONAL SCIENCE FOUNDATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 630.205 What must I include in my drug-free workplace...

  16. 45 CFR 630.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 3 2012-10-01 2012-10-01 false What must I include in my drug-free workplace...) NATIONAL SCIENCE FOUNDATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 630.205 What must I include in my drug-free workplace...

  17. 29 CFR 1472.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false What must I include in my drug-free workplace statement... CONCILIATION SERVICE GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 1472.205 What must I include in my drug-free workplace...

  18. The use of cultured hepatocytes to investigate the metabolism of drugs and mechanisms of drug hepatotoxicity.

    PubMed

    Gómez-Lechón, M J; Ponsoda, X; Bort, R; Castell, J V

    2001-01-01

    Hepatotoxins can be classified as intrinsic when they exert their effects on all individuals in a dose-dependent manner, and as idiosyncratic when their effects are the consequence of an abnormal metabolism of the drug by susceptible individuals (metabolic idiosyncrasy) or of an immune-mediated injury to hepatocytes (allergic hepatitis). Some xenobiotics are electrophilic, and others are biotransformed by the liver into highly reactive metabolites that are usually more toxic than the parent compound. This activation process is the key to many hepatotoxic phenomena. Mitochondria are a frequent target of hepatotoxic drugs, and the alteration of their function has immediate effects on the energy balance of cells (depletion of ATP). Lipid peroxidation, oxidative stress, alteration of Ca(2+) homeostasis, and covalent binding to cell macromolecules are the molecular mechanisms that are frequently involved in the toxicity of xenobiotics. Against these potential hazards, cells have their own defence mechanisms (for example, glutathione, DNA repair, suicide inactivation). Ultimately, toxicity is the balance between bioactivation and detoxification, which determines whether a reactive metabolite elicits a toxic effect. The ultimate goal of in vitro experiments is to generate the type of scientific information needed to identify compounds that are potentially toxic to man. For this purpose, both the design of the experiments and the interpretation of the results are critical.

  19. 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

  20. Xenobiotics and loss of cell adhesion drive distinct transcriptional outcomes by aryl hydrocarbon receptor signaling.

    PubMed

    Hao, Nan; Lee, Kian Leong; Furness, Sebastian G B; Bosdotter, Cecilia; Poellinger, Lorenz; Whitelaw, Murray L

    2012-12-01

    The aryl hydrocarbon receptor (AhR) is a signal-regulated transcription factor, which is canonically activated by the direct binding of xenobiotics. In addition, switching cells from adherent to suspension culture also activates the AhR, representing a nonxenobiotic, physiological activation of AhR signaling. Here, we show that the AhR is recruited to target gene enhancers in both ligand [isopropyl-2-(1,3-dithietane-2-ylidene)-2-[N-(4-methylthiazol-2-yl)carbamoyl]acetate (YH439)]-treated and suspension cells, suggesting a common mechanism of target gene induction between these two routes of AhR activation. However, gene expression profiles critically differ between xenobiotic- and suspension-activated AhR signaling. Por and Cldnd1 were regulated predominantly by ligand treatments, whereas, in contrast, ApoER2 and Ganc were regulated predominantly by the suspension condition. Classic xenobiotic-metabolizing AhR targets such as Cyp1a1, Cyp1b1, and Nqo1 were regulated by both ligand and suspension conditions. Temporal expression patterns of AhR target genes were also found to vary, with examples of transient activation, transient repression, or sustained alterations in expression. Furthermore, sequence analysis coupled with chromatin immunoprecipitation assays and reporter gene analysis identified a functional xenobiotic response element (XRE) in the intron 1 of the mouse Tiparp gene, which was also bound by hypoxia-inducible factor-1α during hypoxia and features a concatemer of four XRE cores (GCGTG). Our data suggest that this XRE concatemer site concurrently regulates the expression of both the Tiparp gene and its cis antisense noncoding RNA after ligand- or suspension-induced AhR activation. This work provides novel insights into how AhR signaling drives different transcriptional programs via the ligand versus suspension modes of activation.

  1. 22 CFR 1008.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true What must I include in my drug-free workplace... FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 1008.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a...

  2. 22 CFR 210.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false What must I include in my drug-free workplace... REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 210.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a...

  3. 45 CFR 1173.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false What must I include in my drug-free workplace... REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 1173.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a...

  4. 49 CFR 32.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false What must I include in my drug-free workplace... REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 32.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a...

  5. 20 CFR 439.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false What must I include in my drug-free workplace... REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 439.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a...

  6. 45 CFR 1155.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false What must I include in my drug-free workplace... REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 1155.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a...

  7. 22 CFR 1509.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true What must I include in my drug-free workplace... REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 1509.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a...

  8. 22 CFR 133.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false What must I include in my drug-free workplace... REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 133.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a...

  9. Key metabolic pathways involved in xenobiotic biotransformation and stress responses revealed by transcriptomics of the mangrove oyster Crassostrea brasiliana.

    PubMed

    Lüchmann, Karim H; Clark, Melody S; Bainy, Afonso C D; Gilbert, Jack A; Craft, John A; Chipman, J Kevin; Thorne, Michael A S; Mattos, Jacó J; Siebert, Marília N; Schroeder, Declan C

    2015-09-01

    The Brazilian oyster Crassostrea brasiliana was challenged to three common environmental contaminants: phenanthrene, diesel fuel water-accommodated fraction (WAF) and domestic sewage. Total RNA was extracted from the gill and digestive gland, and cDNA libraries were sequenced using the 454 FLX platform. The assembled transcriptome resulted in ̃20,000 contigs, which were annotated to produce the first de novo transcriptome for C. brasiliana. Sequences were screened to identify genes potentially involved in the biotransformation of xenobiotics and associated antioxidant defence mechanisms. These gene families included those of the cytochrome P450 (CYP450), 70kDa heat shock, antioxidants, such as glutathione S-transferase, superoxide dismutase, catalase and also multi-drug resistance proteins. Analysis showed that the massive expansion of the CYP450 and HSP70 family due to gene duplication identified in the Crassostrea gigas genome also occurred in C. brasiliana, suggesting these processes form the base of the Crassostrea lineage. Preliminary expression analyses revealed several candidates biomarker genes that were up-regulated during each of the three treatments, suggesting the potential for environmental monitoring. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Comparative investigation of the xenobiotic metabolizing arylamine N-acetyltransferase enzyme family among fungi

    USDA-ARS?s Scientific Manuscript database

    Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes well-characterized in several bacteria and higher eukaryotes. The role of NATs in fungal biology has only recently been investigated. The NAT1 gene of Gibberella moniliformis was the first NAT cloned and characterized from fun...

  11. Identification of Drug Characteristics for Implementing Multiregional Clinical Trials Including Japan.

    PubMed

    Rokuda, Mitsuhiro; Matsumaru, Naoki; Tsukamoto, Katsura

    2018-02-01

    Multiregional clinical trials (MRCT) are a standard strategy used to improve global drug approval efficiency and the feasibility of clinical trials. Japan is the world's third largest drug market with a unique health care system, making it a key inclusion as an operational region for MRCT (MRCT-JP) for global drug development. We aimed to identify the factors required for efficient drug development by comprehensively reviewing the clinical trials of drugs approved in Japan to identify the factors associated with whether or not MRCT-JP is implemented. We surveyed the review reports and summaries of application data published by the Pharmaceuticals and Medical Devices Agency. We identified drugs for which the clinical trial data package included MRCT-JP and selected the same number of drugs for which the clinical trial data package did not include MRCT-JP from the most recent survey period for comparison. We also examined other publication information, in addition to the review reports, as necessary. The influence of each explanatory variable was analyzed by logistic regression analysis, with whether or not MRCT-JP was implemented as the explanatory variable. Statistical significance was set at 5%. In the survey period up to September 2017, 165 drugs developed with MRCT-JP were approved for manufacture and sale in Japan. "Respiratory system," "inhalation," "biological drug," and "under review" evaluation status for the United States, European Union, and other areas, "approved" evaluation status for the United States, "new ingredients," "priority review," "non-Japanese firm," and "Top 1-10" and "Top 11-20" drug sales rankings for pharmaceutical companies were identified as potential factors leading to the implementation of MRCT-JP. In contrast, "general anti-infectives for systemic use," "various," "external," "chemical compound," "unsubmitted" evaluation status for both the United States and European Union, and "Top 51+" drug sales rankings were potential factors for

  12. Comparative genomic and phylogenetic investigation of the xenobiotic metabolizing arylamine N-acetyltransferase enzyme family

    USDA-ARS?s Scientific Manuscript database

    Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes characterized in several bacteria and eukaryotic organisms. We report a comprehensive phylogenetic analysis employing an exhaustive dataset of NAT-homologous sequences recovered through inspection of 2445 genomes. We describe ...

  13. Activity of xenobiotic-metabolizing enzymes in the liver of rats with multi-vitamin deficiency.

    PubMed

    Tutelyan, Victor A; Kravchenko, Lidia V; Aksenov, Ilya V; Trusov, Nikita V; Guseva, Galina V; Kodentsova, Vera M; Vrzhesinskaya, Oksana A; Beketova, Nina A

    2013-01-01

    The purpose of the study was to determine how multi-vitamin deficiency affects xenobiotic-metabolizing enzyme (XME) activities in the rat liver. Vitamin levels and XME activities were studied in the livers of male Wistar rats who were fed for 4 weeks with semi-synthetic diets containing either adequate (100 % of recommended vitamin intake) levels of vitamins (control), or decreased vitamin levels (50 % or 20 % of recommended vitamin intake). The study results have shown that moderate vitamin deficiency (50 %) leads to a decrease of vitamin A levels only, and to a slight increase, as compared with the control, in the following enzyme activities: methoxyresorufin O-dealkylase (MROD) activity of CYP1 A2 - by 34 % (p < 0.05), UDP-glucuronosyl transferase - by 26 % (p < 0.05), and quinone reductase - by 55 % (p < 0.05). Profound vitamin deficiency (20 %) led to a decrease of vitamins A, E, B1, B2, and C, and enzyme activities in the liver: MROD - to 78 % of the control level (p < 0.05), 4-nitrophenol hydroxylase - to 74 % (p < 0.05), heme oxygenase-1 - to 83 % (p < 0.05), and quinone reductase - to 60 % (p < 0.05). At the same time, the UDP-glucuronosyl transferase activity and ethoxyresorufin O-dealkylase activity of CYP1A1, pentoxyresorufin O-dealkylase activity of CYP2B1/2 and 6β-testosterone hydroxylase, as well as the total activity of glutathione transferase did not differ from the control levels. The study has demonstrated that profound multi-vitamin deficiency is associated with a decrease in the expression of CYP1A2 and CYP3A1 mRNAs to 62 % and 79 %, respectively. These data indicated that a short-term but profound multi-vitamin deficiency in rats leads to a decrease in the activities and expression of the some XME that play an important role in detoxification of xenobiotics and metabolism of drugs and antioxidant protection.

  14. The Simplest Flowchart Stating the Mechanisms for Organic Xenobiotics-induced Toxicity: Can it Possibly be Accepted as a "Central Dogma" for Toxic Mechanisms?

    PubMed

    Park, Yeong-Chul; Lee, Sundong; Cho, Myung-Haing

    2014-09-01

    Xenobiotics causing a variety of toxicity in biological systems could be classified as two types, inorganic and organic chemicals. It is estimated that the organic xenobiotics are responsible for approximately 80~90% of chemical-induced toxicity in human population. In the class for toxicology, we have encountered some difficulties in explaining the mechanisms of toxicity caused especially by organic chemicals. Here, a simple flowchart was introduced for explaining the mechanism of toxicity caused by organic xenobiotics, as the central dogma of molecular biology. This flowchart, referred to as a central dogma, was described based on a view of various aspects as follows: direct-acting chemicals vs. indirect-acting chemicals, cytochrome P450-dependent vs. cytochrome P450-independent biotransformation, reactive intermediates, reactivation, toxicokinetics vs. toxicodynamics, and reversibility vs. irreversibility. Thus, the primary objective of this flowchart is to help better understanding of the organic xenobiotics-induced toxic mechanisms, providing a major pathway for toxicity occurring in biological systems.

  15. Administrative claims analysis of the relationship between warfarin use and risk of hemorrhage including drug-drug and drug-disease interactions.

    PubMed

    Zhang, Kui; Young, Christopher; Berger, Jan

    2006-10-01

    Despite the risk of hemorrhage, warfarin is the most commonly used oral anticoagulant today, both as monotherapy and when taken in combination with selected drugs. Warfarin is used most commonly for irregular heartbeat, after a heart attack, and after joint or heart valve replacement surgery. To evaluate the relative risk of hemorrhage in health plan members who received warfarin concomitant with a drug known to cause an interaction or after diagnosis of liver disease or heart failure (HF). A cohort study sample was drawn from an administrative database comprising medical and pharmacy claims for 1.7 million health plan members. A health plan member was defined as anyone who was eligible for pharmacy and medical benefits at any time from October 1, 2003, to September 30, 2004. To be included in the study, a member must have received at least 1 pharmacy claim for warfarin during the study period and been younger than 100 years. Hemorrhage was defined as a diagnosed bleeding episode recorded on a medical claim within 7 calendar days of a fill date for a pharmacy claim (new or refill) for warfarin. The following variables were used to predict the outcome measures: type of drug-drug or drug-disease interaction, patient age and gender, number of unique prescribers during the year for all drugs, specialty of the first prescriber for warfarin, average dose of warfarin, and days of warfarin therapy. Because individuals were followed only during the calendar year under study, the authors have interpreted the days of therapy measured primarily as a control on exposure. The outcome measures are prevalence of drug and disease interactions among members receiving warfarin therapy and the per-patient-per-year and per-member-per-month (PMPM) cost of medical treatment of hemorrhage associated with warfarin therapy including drug and disease interactions. Costs are defined as the total paid amount for a procedure or service after negotiated provider discounts and subtraction of

  16. Do heavy metals and metalloids influence the detoxification of organic xenobiotics in plants?

    PubMed

    Schröder, Peter; Lyubenova, Lyudmila; Huber, Christian

    2009-11-01

    Mixed pollution with trace elements and organic industrial compounds is characteristic for many spill areas and dumping sites. The danger for the environment and human health from such sites is large, and sustainable remediation strategies are urgently needed. Phytoremediation seems to be a cheap and environmentally sound option for the removal of unwanted compounds, and the hyperaccumulation of trace elements and toxic metals is seemingly independent from the metabolism of organic xenobiotics. However, stress reactions, ROS formation and depletion of antioxidants will also cause alterations in xenobiotic detoxification. Here, we investigate the capability of plants to detoxify chlorophenols via glutathione conjugation in a mixed pollution situation. Typha latifolia and Phragmites australis plants for the present study were grown under greenhouse conditions in experimental ponds. A Picea abies L. suspension culture was grown in a growth chamber. Cadmium sulphate, sodium arsenate and lead chloride in concentrations from 10 to 500 microM were administered to plants. Enzymes of interest for the present study were: glutathione transferase (GST), glutathione reductase, ascorbate peroxidase and peroxidase. Measurements were performed according to published methods. GST spectrophotometric assays included the model substrates CDNB, DCNB, NBC, NBoC and the herbicide Fluorodifen. Heavy metals lead to visible stress symptoms in higher plants. Besides one long-term experiment of 72 days duration, the present study shows time and concentration-dependent plant alterations already after 24 and 72 h Cd incubation. P. abies spruce cell cultures react to CdSO(4) and Na(2)HAsO(4) with an oxidative burst, similar to that observed after pathogen attack or elicitor treatment. Cd application resulted in a reduction in GSH and GSSG contents. When a heavy metal mixture containing Na(2)HAsO(4), CdSO(4) and PbCl(2) was applied to cultures, both GSH and GSSG levels declined. Incubation with

  17. General unknown screening procedure for the characterization of human drug metabolites in forensic toxicology: applications and constraints.

    PubMed

    Sauvage, François-Ludovic; Picard, Nicolas; Saint-Marcoux, Franck; Gaulier, Jean-Michel; Lachâtre, Gérard; Marquet, Pierre

    2009-09-01

    LC coupled to single (LC-MS) and tandem (LC-MS/MS) mass spectrometry is recognized as the most powerful analytical tools for metabolic studies in drug discovery. In this article, we describe five cases illustrating the utility of screening xenobiotic metabolites in routine analysis of forensic samples using LC-MS/MS. Analyses were performed using a previously published LC-MS/MS general unknown screening (GUS) procedure developed using a hybrid linear IT-tandem mass spectrometer. In each of the cases presented, the presence of metabolites of xenobiotics was suspected after analyzing urine samples. In two cases, the parent drug was also detected and the metabolites were merely useful to confirm drug intake, but in three other cases, metabolite detection was of actual forensic interest. The presented results indicate that: (i) the GUS procedure developed is useful to detect a large variety of drug metabolites, which would have been hardly detected using targeted methods in the context of clinical or forensic toxicology; (ii) metabolite structure can generally be inferred from their "enhanced" product ion scan spectra; and (iii) structure confirmation can be achieved through in vitro metabolic experiments or through the analysis of urine samples from individuals taking the parent drug.

  18. Monobromobimane occupies a distinct xenobiotic substrate site in glutathione S-transferase π

    PubMed Central

    Ralat, Luis A.; Colman, Roberta F.

    2003-01-01

    Monobromobimane (mBBr), functions as a substrate of porcine glutathione S-transferase π (GST π): The enzyme catalyzes the reaction of mBBr with glutathione. S-(Hydroxyethyl)bimane, a nonreactive analog of monobromobimane, acts as a competitive inhibitor with respect to mBBr as substrate but does not affect the reaction of GST π with another substrate, 1-chloro-2,4-dinitrobenzene (CDNB). In the absence of glutathione, monobromobimane inactivates GST π at pH 7.0 and 25°C as assayed using mBBr as substrate, with a lesser effect on the enzyme’s use of CDNB as substrate. These results indicate that the sites occupied by CDNB and mBBr are not identical. Inactivation is proportional to the incorporation of 2 moles of bimane/mole of subunit. Modification of GST π with mBBr does not interfere with its binding of 8-anilino-1-naphthalene sulfonate, indicating that this hydrophobic site is not the target of monobromobimane. S-Methylglutathione and S-(hydroxyethyl)bimane each yield partial protection against inactivation and decrease reagent incorporation, while glutathionyl-bimane protects completely against inactivation. Peptide analysis after trypsin digestion indicates that mBBr modifies Cys45 and Cys99 equally. Modification of Cys45 is reduced in the presence of S-methylglutathione, indicating that this residue is at or near the glutathione binding region. In contrast, modification of Cys99 is reduced in the presence of S-(hydroxyethyl)bimane, suggesting that this residue is at or near the mBBr xenobiotic substrate binding site. Modification of Cys99 can best be understood by reaction with monobromobimane while it is bound to its xenobiotic substrate site in an alternate orientation. These results support the concept that glutathione S-transferase accomplishes its ability to react with a diversity of substrates in part by harboring distinct xenobiotic substrate sites. PMID:14573868

  19. Monobromobimane occupies a distinct xenobiotic substrate site in glutathione S-transferase pi.

    PubMed

    Ralat, Luis A; Colman, Roberta F

    2003-11-01

    Monobromobimane (mBBr), functions as a substrate of porcine glutathione S-transferase pi (GST pi): The enzyme catalyzes the reaction of mBBr with glutathione. S-(Hydroxyethyl)bimane, a nonreactive analog of monobromobimane, acts as a competitive inhibitor with respect to mBBr as substrate but does not affect the reaction of GST pi with another substrate, 1-chloro-2,4-dinitrobenzene (CDNB). In the absence of glutathione, monobromobimane inactivates GST pi at pH 7.0 and 25 degrees C as assayed using mBBr as substrate, with a lesser effect on the enzyme's use of CDNB as substrate. These results indicate that the sites occupied by CDNB and mBBr are not identical. Inactivation is proportional to the incorporation of 2 moles of bimane/mole of subunit. Modification of GST pi with mBBr does not interfere with its binding of 8-anilino-1-naphthalene sulfonate, indicating that this hydrophobic site is not the target of monobromobimane. S-Methylglutathione and S-(hydroxyethyl)bimane each yield partial protection against inactivation and decrease reagent incorporation, while glutathionyl-bimane protects completely against inactivation. Peptide analysis after trypsin digestion indicates that mBBr modifies Cys45 and Cys99 equally. Modification of Cys45 is reduced in the presence of S-methylglutathione, indicating that this residue is at or near the glutathione binding region. In contrast, modification of Cys99 is reduced in the presence of S-(hydroxyethyl)bimane, suggesting that this residue is at or near the mBBr xenobiotic substrate binding site. Modification of Cys99 can best be understood by reaction with monobromobimane while it is bound to its xenobiotic substrate site in an alternate orientation. These results support the concept that glutathione S-transferase accomplishes its ability to react with a diversity of substrates in part by harboring distinct xenobiotic substrate sites.

  20. Non-targeted, high resolution mass spectrometry strategy for simultaneous monitoring of xenobiotics and endogenous compounds in green sea turtles on the Great Barrier Reef.

    PubMed

    Heffernan, Amy L; Gómez-Ramos, Maria M; Gaus, Caroline; Vijayasarathy, Soumini; Bell, Ian; Hof, Christine; Mueller, Jochen F; Gómez-Ramos, Maria J

    2017-12-01

    Chemical contamination poses a threat to ecosystem, biota and human health, and identifying these hazards is a complex challenge. Traditional hazard identification relies on a priori-defined targets of limited chemical scope, and is generally inappropriate for exploratory studies such as explaining toxicological effects in environmental systems. Here we present a non-target high resolution mass spectrometry environmental monitoring study with multivariate statistical analysis to simultaneously detect biomarkers of exposure (e.g. xenobiotics) and biomarkers of effect in whole turtle blood. Borrowing the concept from clinical chemistry, a case-control sampling approach was used to investigate the potential influence of xenobiotics of anthropogenic origin on free-ranging green sea turtles (Chelonia mydas) from a remote, offshore 'control' site; and two coastal 'case' sites influenced by urban/industrial and agricultural activities, respectively, on the Great Barrier Reef in North Queensland, Australia. Multiple biomarkers of exposure, including sulfonic acids (n=9), a carbamate insecticide metabolite, and other industrial chemicals; and five biomarkers of effect (lipid peroxidation products), were detected in case sites. Additionally, two endogenous biomarkers of neuroinflammation and oxidative stress were identified, and showed moderate-to-strong correlations with clinical measures of inflammation and liver dysfunction. Our data filtering strategy overcomes limitations of traditional a priori selection of target compounds, and adds to the limited environmental xenobiotic metabolomics literature. To our knowledge this is the first case-control study of xenobiotics in marine megafauna, and demonstrates the utility of green sea turtles to link internal and external exposure, to explain potential toxicological effects in environmental systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Two Horizontally Transferred Xenobiotic Resistance Gene Clusters Associated with Detoxification of Benzoxazolinones by Fusarium Species

    PubMed Central

    Glenn, Anthony E.; Davis, C. Britton; Gao, Minglu; Gold, Scott E.; Mitchell, Trevor R.; Proctor, Robert H.; Stewart, Jane E.; Snook, Maurice E.

    2016-01-01

    Microbes encounter a broad spectrum of antimicrobial compounds in their environments and often possess metabolic strategies to detoxify such xenobiotics. We have previously shown that Fusarium verticillioides, a fungal pathogen of maize known for its production of fumonisin mycotoxins, possesses two unlinked loci, FDB1 and FDB2, necessary for detoxification of antimicrobial compounds produced by maize, including the γ-lactam 2-benzoxazolinone (BOA). In support of these earlier studies, microarray analysis of F. verticillioides exposed to BOA identified the induction of multiple genes at FDB1 and FDB2, indicating the loci consist of gene clusters. One of the FDB1 cluster genes encoded a protein having domain homology to the metallo-β-lactamase (MBL) superfamily. Deletion of this gene (MBL1) rendered F. verticillioides incapable of metabolizing BOA and thus unable to grow on BOA-amended media. Deletion of other FDB1 cluster genes, in particular AMD1 and DLH1, did not affect BOA degradation. Phylogenetic analyses and topology testing of the FDB1 and FDB2 cluster genes suggested two horizontal transfer events among fungi, one being transfer of FDB1 from Fusarium to Colletotrichum, and the second being transfer of the FDB2 cluster from Fusarium to Aspergillus. Together, the results suggest that plant-derived xenobiotics have exerted evolutionary pressure on these fungi, leading to horizontal transfer of genes that enhance fitness or virulence. PMID:26808652

  2. 13 CFR 147.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... establish an ongoing drug-free awareness program to inform employees about— (a) The dangers of drug abuse in... 13 Business Credit and Assistance 1 2013-01-01 2013-01-01 false What must I include in my drug... ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (NONPROCUREMENT) Requirements for Recipients...

  3. 13 CFR 147.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... establish an ongoing drug-free awareness program to inform employees about— (a) The dangers of drug abuse in... 13 Business Credit and Assistance 1 2012-01-01 2012-01-01 false What must I include in my drug... ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (NONPROCUREMENT) Requirements for Recipients...

  4. 13 CFR 147.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... establish an ongoing drug-free awareness program to inform employees about— (a) The dangers of drug abuse in... 13 Business Credit and Assistance 1 2014-01-01 2014-01-01 false What must I include in my drug... ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (NONPROCUREMENT) Requirements for Recipients...

  5. 13 CFR 147.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... establish an ongoing drug-free awareness program to inform employees about— (a) The dangers of drug abuse in... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false What must I include in my drug... ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (NONPROCUREMENT) Requirements for Recipients...

  6. 14 CFR 1267.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... establish an ongoing drug-free awareness program to inform employees about— (a) The dangers of drug abuse in... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false What must I include in my drug-free... ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for...

  7. 2 CFR 182.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 2 Grants and Agreements 1 2014-01-01 2014-01-01 false What must I include in my drug-free...

  8. 13 CFR 147.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... establish an ongoing drug-free awareness program to inform employees about— (a) The dangers of drug abuse in... 13 Business Credit and Assistance 1 2011-01-01 2011-01-01 false What must I include in my drug... ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (NONPROCUREMENT) Requirements for Recipients...

  9. 14 CFR 1267.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... establish an ongoing drug-free awareness program to inform employees about— (a) The dangers of drug abuse in... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false What must I include in my drug-free... ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for...

  10. 2 CFR 182.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 2 Grants and Agreements 1 2011-01-01 2011-01-01 false What must I include in my drug-free...

  11. 14 CFR 1267.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... establish an ongoing drug-free awareness program to inform employees about— (a) The dangers of drug abuse in... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false What must I include in my drug-free... ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for...

  12. 14 CFR 1267.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... establish an ongoing drug-free awareness program to inform employees about— (a) The dangers of drug abuse in... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true What must I include in my drug-free... ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for...

  13. Cryptic indole hydroxylation by a non-canonical terpenoid cyclase parallels bacterial xenobiotic detoxification

    NASA Astrophysics Data System (ADS)

    Kugel, Susann; Baunach, Martin; Baer, Philipp; Ishida-Ito, Mie; Sundaram, Srividhya; Xu, Zhongli; Groll, Michael; Hertweck, Christian

    2017-06-01

    Terpenoid natural products comprise a wide range of molecular architectures that typically result from C-C bond formations catalysed by classical type I/II terpene cyclases. However, the molecular diversity of biologically active terpenoids is substantially increased by fully unrelated, non-canonical terpenoid cyclases. Their evolutionary origin has remained enigmatic. Here we report the in vitro reconstitution of an unusual flavin-dependent bacterial indoloterpenoid cyclase, XiaF, together with a designated flavoenzyme-reductase (XiaP) that mediates a key step in xiamycin biosynthesis. The crystal structure of XiaF with bound FADH2 (at 2.4 Å resolution) and phylogenetic analyses reveal that XiaF is, surprisingly, most closely related to xenobiotic-degrading enzymes. Biotransformation assays show that XiaF is a designated indole hydroxylase that can be used for the production of indigo and indirubin. We unveil a cryptic hydroxylation step that sets the basis for terpenoid cyclization and suggest that the cyclase has evolved from xenobiotics detoxification enzymes.

  14. Hepatotoxicity of Herbal Supplements Mediated by Modulation of Cytochrome P450

    PubMed Central

    Chen, Taosheng

    2017-01-01

    Herbal supplements are a significant source of drug-drug interactions (DDIs), herb-drug interactions, and hepatotoxicity. Cytochrome P450 (CYP450) enzymes metabolize a large number of FDA-approved pharmaceuticals and herbal supplements. This metabolism of pharmaceuticals and supplements can be augmented by concomitant use of either pharmaceuticals or supplements. The xenobiotic receptors constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) can respond to xenobiotics by increasing the expression of a large number of genes that are involved in the metabolism of xenobiotics, including CYP450s. Conversely, but not exclusively, many xenobiotics can inhibit the activity of CYP450s. Induction of the expression or inhibition of the activity of CYP450s can result in DDIs and toxicity. Currently, the United States (US) Food and Drug Administration does not require the investigation of the interactions of herbal supplements and CYP450s. This review provides a summary of herbal supplements that inhibit CYP450s, induce the expression of CYP450s, and/or whose toxicity is mediated by CYP450s. PMID:29117101

  15. 45 CFR 630.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 45 Public Welfare 3 2012-10-01 2012-10-01 false What must I include in my drug-free awareness...

  16. 24 CFR 21.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false What must I include in my drug-free...

  17. 45 CFR 630.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 45 Public Welfare 3 2011-10-01 2011-10-01 false What must I include in my drug-free awareness...

  18. 29 CFR 1472.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 29 Labor 4 2014-07-01 2014-07-01 false What must I include in my drug-free awareness program? 1472...

  19. 45 CFR 630.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 45 Public Welfare 3 2014-10-01 2014-10-01 false What must I include in my drug-free awareness...

  20. 2 CFR 1401.315 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 2 Grants and Agreements 1 2014-01-01 2014-01-01 false What must I include in my drug-free...

  1. 45 CFR 630.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 45 Public Welfare 3 2013-10-01 2013-10-01 false What must I include in my drug-free awareness...

  2. 29 CFR 1472.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 29 Labor 4 2010-07-01 2010-07-01 false What must I include in my drug-free awareness program? 1472...

  3. 29 CFR 1472.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 29 Labor 4 2011-07-01 2011-07-01 false What must I include in my drug-free awareness program? 1472...

  4. 29 CFR 1472.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 29 Labor 4 2012-07-01 2012-07-01 false What must I include in my drug-free awareness program? 1472...

  5. 40 CFR 36.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false What must I include in my drug-free...

  6. 24 CFR 21.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 24 Housing and Urban Development 1 2011-04-01 2011-04-01 false What must I include in my drug-free...

  7. 29 CFR 1472.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 29 Labor 4 2013-07-01 2013-07-01 false What must I include in my drug-free awareness program? 1472...

  8. 2 CFR 1401.315 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 2 Grants and Agreements 1 2013-01-01 2013-01-01 false What must I include in my drug-free...

  9. 45 CFR 630.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 45 Public Welfare 3 2010-10-01 2010-10-01 false What must I include in my drug-free awareness...

  10. 2 CFR 1401.315 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c) Any... may impose upon them for drug abuse violations occurring in the workplace. ... 2 Grants and Agreements 1 2012-01-01 2012-01-01 false What must I include in my drug-free...

  11. Gut Pharmacomicrobiomics: the tip of an iceberg of complex interactions between drugs and gut-associated microbes

    PubMed Central

    2012-01-01

    The influence of resident gut microbes on xenobiotic metabolism has been investigated at different levels throughout the past five decades. However, with the advance in sequencing and pyrotagging technologies, addressing the influence of microbes on xenobiotics had to evolve from assessing direct metabolic effects on toxins and botanicals by conventional culture-based techniques to elucidating the role of community composition on drugs metabolic profiles through DNA sequence-based phylogeny and metagenomics. Following the completion of the Human Genome Project, the rapid, substantial growth of the Human Microbiome Project (HMP) opens new horizons for studying how microbiome compositional and functional variations affect drug action, fate, and toxicity (pharmacomicrobiomics), notably in the human gut. The HMP continues to characterize the microbial communities associated with the human gut, determine whether there is a common gut microbiome profile shared among healthy humans, and investigate the effect of its alterations on health. Here, we offer a glimpse into the known effects of the gut microbiota on xenobiotic metabolism, with emphasis on cases where microbiome variations lead to different therapeutic outcomes. We discuss a few examples representing how the microbiome interacts with human metabolic enzymes in the liver and intestine. In addition, we attempt to envisage a roadmap for the future implications of the HMP on therapeutics and personalized medicine. PMID:23194438

  12. 2 CFR 1401.315 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... 2 Grants and Agreements 1 2011-01-01 2011-01-01 false What must I include in my drug-free...

  13. 2 CFR 182.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... 2 Grants and Agreements 1 2013-01-01 2013-01-01 false What must I include in my drug-free...

  14. 32 CFR 26.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... 32 National Defense 1 2011-07-01 2011-07-01 false What must I include in my drug-free awareness...

  15. 32 CFR 26.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... 32 National Defense 1 2014-07-01 2014-07-01 false What must I include in my drug-free awareness...

  16. 32 CFR 26.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... 32 National Defense 1 2013-07-01 2013-07-01 false What must I include in my drug-free awareness...

  17. 32 CFR 26.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... 32 National Defense 1 2010-07-01 2010-07-01 false What must I include in my drug-free awareness...

  18. 32 CFR 26.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... 32 National Defense 1 2012-07-01 2012-07-01 false What must I include in my drug-free awareness...

  19. 2 CFR 182.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... 2 Grants and Agreements 1 2012-01-01 2012-01-01 false What must I include in my drug-free...

  20. Intermolecular Forces as a Key to Understanding the Environmental Fate of Organic Xenobiotics

    ERIC Educational Resources Information Center

    Casey, Ryan E.; Pittman, Faith A.

    2005-01-01

    A module that can be incorporated into chemistry or environmental science classes at the high school or undergraduate level is described. The module is divided into a series of segments, each of which incorporates several concepts and results in students making significant predictions about the behavior of organic xenobiotics.

  1. 2 CFR 182.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... 2 Grants and Agreements 1 2010-01-01 2010-01-01 false What must I include in my drug-free...

  2. The Simplest Flowchart Stating the Mechanisms for Organic Xenobiotics-induced Toxicity: Can it Possibly be Accepted as a “Central Dogma” for Toxic Mechanisms?

    PubMed Central

    Lee, Sundong; Cho, Myung-Haing

    2014-01-01

    Xenobiotics causing a variety of toxicity in biological systems could be classified as two types, inorganic and organic chemicals. It is estimated that the organic xenobiotics are responsible for approximately 80~90% of chemical-induced toxicity in human population. In the class for toxicology, we have encountered some difficulties in explaining the mechanisms of toxicity caused especially by organic chemicals. Here, a simple flowchart was introduced for explaining the mechanism of toxicity caused by organic xenobiotics, as the central dogma of molecular biology. This flowchart, referred to as a central dogma, was described based on a view of various aspects as follows: direct-acting chemicals vs. indirect-acting chemicals, cytochrome P450-dependent vs. cytochrome P450-independent biotransformation, reactive intermediates, reactivation, toxicokinetics vs. toxicodynamics, and reversibility vs. irreversibility. Thus, the primary objective of this flowchart is to help better understanding of the organic xenobiotics-induced toxic mechanisms, providing a major pathway for toxicity occurring in biological systems. PMID:25343011

  3. 21 CFR 1405.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 21 Food and Drugs 9 2013-04-01 2013-04-01 false What must I include in my drug-free awareness...

  4. 21 CFR 1405.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 21 Food and Drugs 9 2014-04-01 2014-04-01 false What must I include in my drug-free awareness...

  5. 21 CFR 1405.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 21 Food and Drugs 9 2011-04-01 2011-04-01 false What must I include in my drug-free awareness...

  6. 21 CFR 1405.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 21 Food and Drugs 9 2010-04-01 2010-04-01 false What must I include in my drug-free awareness...

  7. 21 CFR 1405.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 21 Food and Drugs 9 2012-04-01 2012-04-01 false What must I include in my drug-free awareness...

  8. Characterisation of human tubular cell monolayers as a model of proximal tubular xenobiotic handling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brown, Colin D.A.; Sayer, Rachel; Windass, Amy S.

    2008-12-15

    The aim of this study was to determine whether primary human tubular cell monolayers could provide a powerful tool with which to investigate the renal proximal tubular handling of xenobiotics. Human proximal and distal tubule/collecting duct cells were grown as monolayers on permeable filter supports. After 10 days in culture, proximal tubule cells remained differentiated and expressed a wide palette of transporters at the mRNA level including NaPi-IIa, SGLT1, SGLT2, OCT2, OCTN2, OAT1, OAT3, OAT4, MDR1, MRP2 and BCRP. At the protein level, the expression of a subset of transporters including NaPi-IIa, OAT1 and OAT3 was demonstrated using immunohistochemistry. Analysismore » of the expression of the ATP binding cassette efflux pumps MDR1, MRP2 and BCRP confirmed their apical membrane localisation. At the functional level, tubule cell monolayers retain the necessary machinery to mediate the net secretion of the prototypic substrates; PAH and creatinine. PAH secretion across the monolayer consisted of the uptake of PAH across the basolateral membrane by OAT1 and OAT3 and the apical exit of PAH by a probenecid and MK571-sensitive route consistent with actions of MRP2 or MRP4. Creatinine secretion was by OCT2-mediated uptake at the basolateral membrane and via MDR1 at the apical membrane. Functional expression of MDR1 and BCRP at the apical membrane was also demonstrated using a Hoechst 33342 dye. Similarly, measurement of calcein efflux demonstrated the functional expression of MRP2 at the apical membrane of cell monolayers. In conclusion, human tubular cell monolayers provide a powerful tool to investigate renal xenobiotic handling.« less

  9. Generation of human pluripotent stem cell-derived hepatocyte-like cells for drug toxicity screening.

    PubMed

    Takayama, Kazuo; Mizuguchi, Hiroyuki

    2017-02-01

    Because drug-induced liver injury is one of the main reasons for drug development failures, it is important to perform drug toxicity screening in the early phase of pharmaceutical development. Currently, primary human hepatocytes are most widely used for the prediction of drug-induced liver injury. However, the sources of primary human hepatocytes are limited, making it difficult to supply the abundant quantities required for large-scale drug toxicity screening. Therefore, there is an urgent need for a novel unlimited, efficient, inexpensive, and predictive model which can be applied for large-scale drug toxicity screening. Human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells are able to replicate indefinitely and differentiate into most of the body's cell types, including hepatocytes. It is expected that hepatocyte-like cells generated from human ES/iPS cells (human ES/iPS-HLCs) will be a useful tool for drug toxicity screening. To apply human ES/iPS-HLCs to various applications including drug toxicity screening, homogenous and functional HLCs must be differentiated from human ES/iPS cells. In this review, we will introduce the current status of hepatocyte differentiation technology from human ES/iPS cells and a novel method to predict drug-induced liver injury using human ES/iPS-HLCs. Copyright © 2016 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  10. GENE EXPRESSION PROFILING OF XENOBIOTIC METABOLIZING ENZYMES (XMES) IN THE AGING MALE FISHER RAT

    EPA Science Inventory

    Detoxification and elimination of xenobiotics is a major function of the liver and is important in maintaining the metabolic homeostasis of the organism. The degree to which aging affects hepatic metabolism is not known. The expression of XMEs, in part, determines the fate of the...

  11. PXR as a mediator of herb-drug interaction.

    PubMed

    Hogle, Brett C; Guan, Xiudong; Folan, M Maggie; Xie, Wen

    2018-04-01

    Medicinal herbs have been a part of human medicine for thousands of years. The herb-drug interaction is an extension of drug-drug interaction, in which the consumptions of herbs cause alterations in the metabolism of drugs the patients happen to take at the same time. The pregnane X receptor (PXR) has been established as one of the most important transcriptional factors that regulate the expression of phase I enzymes, phase II enzymes, and drug transporters in the xenobiotic responses. Since its initial discovery, PXR has been implicated in multiple herb-drug interactions that can lead to alterations of the drug's pharmacokinetic properties and cause fluctuating therapeutic efficacies, possibly leading to complications. Regions of the world that heavily incorporate herbalism into their primary health care and people turning to alternative medicines as a personal choice could be at risk for adverse reactions or unintended results from these interactions. This article is intended to highlight our understanding of the PXR-mediated herb-drug interactions. Copyright © 2017. Published by Elsevier B.V.

  12. 7 CFR 3021.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false What must I include in my drug-free workplace...-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 3021.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a) Tells...

  13. 22 CFR 133.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false What must I include in my drug-free workplace statement? 133.205 Section 133.205 Foreign Relations DEPARTMENT OF STATE MISCELLANEOUS GOVERNMENTWIDE... § 133.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a...

  14. 29 CFR 94.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true What must I include in my drug-free workplace statement? 94... WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 94.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a) Tells your employees...

  15. 22 CFR 312.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true What must I include in my drug-free workplace... WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 312.205 What must I include in my drug-free workplace statement? You must publish a statement that— (a) Tells your employees...

  16. Pharmacokinetic and pharmacodynamic drug interactions with ethanol (alcohol).

    PubMed

    Chan, Lingtak-Neander; Anderson, Gail D

    2014-12-01

    Ethanol (alcohol) is one of the most widely used legal drugs in the world. Ethanol is metabolized by alcohol dehydrogenase (ADH) and the cytochrome P450 (CYP) 2E1 drug-metabolizing enzyme that is also responsible for the biotransformation of xenobiotics and fatty acids. Drugs that inhibit ADH or CYP2E1 are the most likely theoretical compounds that would lead to a clinically significant pharmacokinetic interaction with ethanol, which include only a limited number of drugs. Acute ethanol primarily alters the pharmacokinetics of other drugs by changing the rate and extent of absorption, with more limited effects on clearance. Both acute and chronic ethanol use can cause transient changes to many physiologic responses in different organ systems such as hypotension and impairment of motor and cognitive functions, resulting in both pharmacokinetic and pharmacodynamic interactions. Evaluating drug interactions with long-term use of ethanol is uniquely challenging. Specifically, it is difficult to distinguish between the effects of long-term ethanol use on liver pathology and chronic malnutrition. Ethanol-induced liver disease results in decreased activity of hepatic metabolic enzymes and changes in protein binding. Clinical studies that include patients with chronic alcohol use may be evaluating the effects of mild cirrhosis on liver metabolism, and not just ethanol itself. The definition of chronic alcohol use is very inconsistent, which greatly affects the quality of the data and clinical application of the results. Our study of the literature has shown that a significantly higher volume of clinical studies have focused on the pharmacokinetic interactions of ethanol and other drugs. The data on pharmacodynamic interactions are more limited and future research addressing pharmacodynamic interactions with ethanol, especially regarding the non-central nervous system effects, is much needed.

  17. Forensic toxicology in drug-facilitated sexual assault.

    PubMed

    Dinis-Oliveira, Ricardo Jorge; Magalhães, Teresa

    2013-09-01

    The low rates of reporting, prosecution and conviction that characterize sexual assault, is likely even more evident in drug-facilitated cases. Typically, in these crimes, victims are incapacitated and left unable to resist sexual advances, unconscious, unable to fight off the abuser or to say "no" and unable to clearly remember the circumstances surrounding the events due to anterograde amnesia. The consequence is the delay in performing toxicological analysis aggravated by the reluctance of the victim to disclose the crime. Moreover since "date rape drugs" are often consumed with ethanol and exhibit similar toxicodynamic effects, the diagnosis is erroneously performed as being classical ethanol intoxication. Therefore, it is imperative to rapidly consider toxicological analysis in drug-facilitated sexual assaults. The major focus of this review is to harmonize practical approaches and guidelines to rapidly uncover drug-facilitated sexual assault, namely issues related to when to perform toxicological analysis, toxicological requests, samples to be collected, storage, preservation and transport precautions and xenobiotics or endobiotics to be analyzed.

  18. 28 CFR 83.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 28 Judicial Administration 2 2012-07-01 2012-07-01 false What must I include in my drug-free...

  19. 28 CFR 83.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 28 Judicial Administration 2 2011-07-01 2011-07-01 false What must I include in my drug-free...

  20. 28 CFR 83.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 28 Judicial Administration 2 2014-07-01 2014-07-01 false What must I include in my drug-free...

  1. 28 CFR 83.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 28 Judicial Administration 2 2013-07-01 2013-07-01 false What must I include in my drug-free...

  2. 28 CFR 83.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 28 Judicial Administration 2 2010-07-01 2010-07-01 false What must I include in my drug-free...

  3. 14 CFR § 1267.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... establish an ongoing drug-free awareness program to inform employees about— (a) The dangers of drug abuse in... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false What must I include in my drug-free... ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for...

  4. [Carbohydrate metabolism in acute poisoning with xenobiotics].

    PubMed

    Pach, Dorota; Szurkowska, Magdalena; Szafraniec, Krystyna; Targosz, Dorota; Sułek, Monika; Kamenczak, Aleksandra; Huszno, Bohdan

    2007-01-01

    The aim of the study was to evaluate carbohydrate metabolism in patients hospitalised because of acute intoxication with xenobiotics. An analysis of 3628 patients (1553 females and 2075 males; age: 40.6 +/- 15.9 y) hospitalized at the Ward of Toxicology and Environmental Diseases because of acute poisoning in 2004-2006 was done. The patients with diabetes mellitus diagnosed prior to hospitalisation were excluded from the analysis. The blood ethanol concentration was measured, medication drugs and/or psychoactive substance screening test were performed in all patients on admission. Fasting glucose level on admission and control level on second or third day of hospitalisation were determined. Risk ratio of hyperglycaemia according to toxic agent was assessed using multiple regression model considering age, gender, and the patient education. In 18.2% (398 males and 254 females) of the patients the blood glucose level on admission was > or = 7.8 mmol/l; in u 3.6% (78 males and 50 females) > or = 11.1 mmol/l. In 24 (0.6%) of the patients glycaemia on admission was < or = 3.5 mmol/l. Control fasting glucose level of > or = 7.0 mmol/l was determined in 115 males and 76 female patients. 42% elevation in risk of hyperglycaemia was noted in acute carbon monoxide poisoning (OR = 1.42; 95% PU: 1.11-1.82). In ethanol intoxicated patients 12% drop in risk of hyperglycaemia was noted (OR = 0.88; 95% PU: 0.72-1.07). Benzodiazepine poisoning diminished risk of hyperglycaemia in 36% (OR=0.64; 95%PU: 0.48-0.84). Risk of hyperglycaemia in poisoning by medicines co-ingested with ethanol was always lower compared to poisoning with the single agent. A higher risk of hyperglycaemia was related to acute carbon monoxide poisoning whereas lower risk of hyperglycaemia was attributed to benzodiazepines and alcohol. A frequency of hypoglycaemia in the group of poisoned patients was much more lower compared to hyperglycaemia.

  5. 22 CFR 1509.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 2 2012-04-01 2009-04-01 true What must I include in my drug-free awareness...

  6. 22 CFR 133.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 1 2010-04-01 2010-04-01 false What must I include in my drug-free awareness...

  7. 22 CFR 1509.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 2 2010-04-01 2010-04-01 true What must I include in my drug-free awareness...

  8. 49 CFR 32.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 49 Transportation 1 2010-10-01 2010-10-01 false What must I include in my drug-free awareness...

  9. 43 CFR 43.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false What must I include in my drug-free...

  10. 45 CFR 1155.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 45 Public Welfare 3 2010-10-01 2010-10-01 false What must I include in my drug-free awareness...

  11. 15 CFR 29.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false What must I include in my drug-free...

  12. 15 CFR 29.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false What must I include in my drug-free...

  13. 22 CFR 1509.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 2 2014-04-01 2014-04-01 false What must I include in my drug-free awareness...

  14. 22 CFR 210.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 1 2011-04-01 2011-04-01 false What must I include in my drug-free awareness...

  15. 22 CFR 1008.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 2 2012-04-01 2009-04-01 true What must I include in my drug-free awareness...

  16. 34 CFR 84.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 34 Education 1 2011-07-01 2011-07-01 false What must I include in my drug-free awareness program...

  17. 45 CFR 1155.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 45 Public Welfare 3 2011-10-01 2011-10-01 false What must I include in my drug-free awareness...

  18. 34 CFR 84.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 34 Education 1 2010-07-01 2010-07-01 false What must I include in my drug-free awareness program...

  19. 49 CFR 32.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 49 Transportation 1 2013-10-01 2013-10-01 false What must I include in my drug-free awareness...

  20. 49 CFR 32.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 49 Transportation 1 2014-10-01 2014-10-01 false What must I include in my drug-free awareness...

  1. 22 CFR 210.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 1 2010-04-01 2010-04-01 false What must I include in my drug-free awareness...

  2. 34 CFR 84.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 34 Education 1 2014-07-01 2014-07-01 false What must I include in my drug-free awareness program...

  3. 22 CFR 133.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 1 2011-04-01 2011-04-01 false What must I include in my drug-free awareness...

  4. 45 CFR 1155.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 45 Public Welfare 3 2014-10-01 2014-10-01 false What must I include in my drug-free awareness...

  5. 22 CFR 133.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 1 2013-04-01 2013-04-01 false What must I include in my drug-free awareness...

  6. 22 CFR 1509.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 2 2013-04-01 2009-04-01 true What must I include in my drug-free awareness...

  7. 22 CFR 133.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 1 2014-04-01 2014-04-01 false What must I include in my drug-free awareness...

  8. 49 CFR 32.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 49 Transportation 1 2011-10-01 2011-10-01 false What must I include in my drug-free awareness...

  9. 22 CFR 1008.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 2 2013-04-01 2009-04-01 true What must I include in my drug-free awareness...

  10. 22 CFR 1008.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 2 2014-04-01 2014-04-01 false What must I include in my drug-free awareness...

  11. 22 CFR 1008.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 2 2010-04-01 2010-04-01 true What must I include in my drug-free awareness...

  12. 45 CFR 1155.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 45 Public Welfare 3 2013-10-01 2013-10-01 false What must I include in my drug-free awareness...

  13. 45 CFR 1173.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 45 Public Welfare 3 2010-10-01 2010-10-01 false What must I include in my drug-free awareness...

  14. 34 CFR 84.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 34 Education 1 2013-07-01 2013-07-01 false What must I include in my drug-free awareness program...

  15. 15 CFR 29.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false What must I include in my drug-free...

  16. 22 CFR 1509.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 2 2011-04-01 2009-04-01 true What must I include in my drug-free awareness...

  17. 45 CFR 1155.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 45 Public Welfare 3 2012-10-01 2012-10-01 false What must I include in my drug-free awareness...

  18. 22 CFR 133.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 1 2012-04-01 2012-04-01 false What must I include in my drug-free awareness...

  19. 20 CFR 439.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false What must I include in my drug-free awareness...

  20. 34 CFR 84.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 34 Education 1 2012-07-01 2012-07-01 false What must I include in my drug-free awareness program...

  1. 22 CFR 1008.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 22 Foreign Relations 2 2011-04-01 2009-04-01 true What must I include in my drug-free awareness...

  2. 15 CFR 29.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 15 Commerce and Foreign Trade 1 2012-01-01 2012-01-01 false What must I include in my drug-free...

  3. 49 CFR 32.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 49 Transportation 1 2012-10-01 2012-10-01 false What must I include in my drug-free awareness...

  4. 15 CFR 29.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...-free awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b..., and employee assistance programs; and (d) The penalties that you may impose upon them for drug abuse... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 false What must I include in my drug-free...

  5. Cross-induction of detoxification genes by environmental xenobiotics and insecticides in the mosquito Aedes aegypti: impact on larval tolerance to chemical insecticides.

    PubMed

    Poupardin, Rodolphe; Reynaud, Stéphane; Strode, Clare; Ranson, Hilary; Vontas, John; David, Jean-Philippe

    2008-05-01

    The effect of exposure of Aedes aegypti larvae to sub-lethal doses of the pyrethroid insecticide permethrin, the organophosphate temephos, the herbicide atrazine, the polycyclic aromatic hydrocarbon fluoranthene and the heavy metal copper on their subsequent tolerance to insecticides, detoxification enzyme activities and expression of detoxification genes was investigated. Bioassays revealed a moderate increase in larval tolerance to permethrin following exposure to fluoranthene and copper while larval tolerance to temephos increased moderately after exposure to atrazine, copper and permethrin. Cytochrome P450 monooxygenases activities were induced in larvae exposed to permethrin, fluoranthene and copper while glutathione S-transferase activities were induced after exposure to fluoranthene and repressed after exposure to copper. Microarray screening of the expression patterns of all detoxification genes following exposure to each xenobiotic with the Aedes Detox Chip identified multiple genes induced by xenobiotics and insecticides. Further expression studies using real-time quantitative PCR confirmed the induction of multiple CYP genes and one carboxylesterase gene by insecticides and xenobiotics. Overall, this study reveals the potential of xenobiotics found in polluted mosquito breeding sites to affect their tolerance to insecticides, possibly through the cross-induction of particular detoxification genes. Molecular mechanisms involved and impact on mosquito control strategies are discussed.

  6. 22 CFR 312.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 22 Foreign Relations 2 2010-04-01 2010-04-01 true What must I include in my drug-free awareness...

  7. 7 CFR 3021.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 7 Agriculture 15 2011-01-01 2011-01-01 false What must I include in my drug-free awareness program...

  8. 22 CFR 312.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 22 Foreign Relations 2 2013-04-01 2009-04-01 true What must I include in my drug-free awareness...

  9. 10 CFR 607.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... awareness program to inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy... assistance programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring... 10 Energy 4 2010-01-01 2010-01-01 false What must I include in my drug-free awareness program? 607...

  10. 29 CFR 94.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 29 Labor 1 2014-07-01 2013-07-01 true What must I include in my drug-free awareness program? 94...

  11. 7 CFR 3021.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 7 Agriculture 15 2012-01-01 2012-01-01 false What must I include in my drug-free awareness program...

  12. 22 CFR 312.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 22 Foreign Relations 2 2014-04-01 2014-04-01 false What must I include in my drug-free awareness...

  13. 29 CFR 94.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 29 Labor 1 2012-07-01 2012-07-01 false What must I include in my drug-free awareness program? 94...

  14. 22 CFR 312.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 22 Foreign Relations 2 2011-04-01 2009-04-01 true What must I include in my drug-free awareness...

  15. 7 CFR 3021.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 7 Agriculture 15 2010-01-01 2010-01-01 false What must I include in my drug-free awareness program...

  16. 22 CFR 312.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 22 Foreign Relations 2 2012-04-01 2009-04-01 true What must I include in my drug-free awareness...

  17. 29 CFR 94.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 29 Labor 1 2013-07-01 2013-07-01 false What must I include in my drug-free awareness program? 94...

  18. 29 CFR 94.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 29 Labor 1 2011-07-01 2011-07-01 false What must I include in my drug-free awareness program? 94...

  19. 29 CFR 94.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... inform employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a... programs; and (d) The penalties that you may impose upon them for drug abuse violations occurring in the... 29 Labor 1 2010-07-01 2010-07-01 true What must I include in my drug-free awareness program? 94...

  20. 36 CFR § 1212.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true What must I include in my drug...

  1. Phylogenetic and biological investigation of the xenobiotic metabolizing arylamine N-acetyltransferase enzyme family among fungi

    USDA-ARS?s Scientific Manuscript database

    Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes well-characterized in several bacteria and eukaryotic organisms. The role of NATs in fungal biology has only recently been investigated. The NAT1 (FDB2) gene of Fusarium verticillioides was the first NAT cloned and character...

  2. Use of biomarkers to evaluate the ecological risk of xenobiotics associated with agriculture.

    PubMed

    Lima, Liana Bezerra Dias de; Morais, Paula Benevides de; Andrade, Ricardo Lopes Tortorela de; Mattos, Luciana Vieira; Moron, Sandro Estevan

    2018-06-01

    This research aimed to evaluate the ecological risk of xenobiotics associated with agricultural activities by determining metal contents and biomarker responses using tucunaré (Cichla sp.) as a bioindicator. The work was conducted in the southwest region of the state of Tocantins, in the cities of Lagoa da Confusão and Pium. Water samples and specimens of Cichla sp. were collected in the Javaés and Formoso Rivers at three collection points (A, B and C). The concentrations of Cd, Pb, Cu, Cr, Mn, Ni and Zn in water and fish were analyzed. In fish, genotoxic, biochemical (glucose serum levels, AST (aspartate aminotransferase) and ALT (alanine aminotransferase) and histological (gills and liver) biomarkers were assessed. In the water, the Cr and Mn concentrations at the three collection points exceeded the values for Class 1 rivers. In the muscle, Cr was above the maximum limit allowed for human consumption at the three collection points, although the values at Points B and C were not significantly different from that at Point A (p > 0.05). At the three collection points, the micronucleus test revealed a low frequency of micronuclei. Significant hyperglycemia and a decrease in the AST activity of the fish collected at Point C was observed. In the gills, the most frequent alterations were at Stages I and II, which indicated mild to moderate damage, and epithelial detachment was the most frequent variation. In the liver tissue, the most frequently observed histological changes were at Stages I and II and included cytoplasmic vacuolization, nuclear hypertrophy, dilated sinusoids and bile stagnation. The integrated evaluation of these biomarkers indicated that fish collected from areas with intense agricultural activities presented adaptive responses that were likely caused by the availability and bioaccumulation of certain xenobiotics in the environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Studying Interactions of Drugs with Cell Membrane Nutrient Transporters: New Frontiers of Proteoliposome Nanotechnology.

    PubMed

    Scalise, Mariafrancesca; Galluccio, Michele; Pochini, Lorena; Console, Lara; Barile, Maria; Giangregorio, Nicola; Tonazzi, Annamaria; Indiveri, Cesare

    2017-01-01

    Transport systems are hydrophobic proteins localized in cell membranes where they mediate transmembrane flow of nutrients, ions and any other compounds essential for cell metabolism. More than 400 transporters of the SoLuteCarrier (SLC) group are present in human cells. Transporters take contacts also with xenobiotics, thus mediating absorption and/or interaction with these exogenous compounds. Since drugs belong to xenobiotics, transporters gained interest also in drug discovery. Transporters differentially expressed in pathological conditions are exploited as drug targets. Among the methodologies for defining drug interactions, in silico ligand screening and intact cell transport assay were the most diffused, so far. The first is a predictive methodology based on docking chemicals to transporters. It presents limitations due to the small number of human transporter 3D structures that have to be constructed by homology modeling. Intact cells are used for testing effects of drugs and for validating predictions. The challenges of handling this very complex experimental system, are the interferences caused by other transporters and/or intracellular enzymes. Thus, methodologies with lower complexity are welcome. One of the most updated is the proteoliposome nanotechnology consisting in a cell mimicking phospholipid membrane in which a purified transporter is inserted. In this system, drug-transporter interaction can be studied defining kinetics and mechanisms. Several data have been obtained by proteoliposome nanotechnology. An overview of data obtained on the organic cation transporters OCTN1, OCTN2 and on the amino acid transporters ASCT2 and B0AT1 will be presented. Standardized procedures, expected to be pointed out, will enlarge the assay to High Throughput Screenings. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  4. Proteomic analysis of drought resistance in crabapple seedlings primed by the xenobiotic Beta-aminobutyric acid

    USDA-ARS?s Scientific Manuscript database

    In a variety of annual crops and model plants, the xenobiotic DL-Beta-aminobutyric acid (BABA) has been shown to enhance disease resistance and increase salt, drought and thermotolerance. BABA does not activate stress genes directly, but sensitizes plants to respond more quickly and strongly to biot...

  5. Transformation of RDX and other energetic compounds by xenobiotic reductases XenA and XenB

    PubMed Central

    McClay, Kevin; Hawari, Jalal; Paquet, Louise; Malone, Thomas E.; Fox, Brian G.; Steffan, Robert J.

    2017-01-01

    The transformation of explosives, including hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), by xenobiotic reductases XenA and XenB (and the bacterial strains harboring these enzymes) under both aerobic and anaerobic conditions was assessed. Under anaerobic conditions, Pseudomonas fluorescens I-C (XenB) degraded RDX faster than Pseudomonas putida II-B (XenA), and transformation occurred when the cells were supplied with sources of both carbon (succinate) and nitrogen (NH4+), but not when only carbon was supplied. Transformation was always faster under anaerobic conditions compared to aerobic conditions, with both enzymes exhibiting a O2 concentration-dependent inhibition of RDX transformation. The primary degradation pathway for RDX was conversion to methylenedinitramine and then to formaldehyde, but a minor pathway that produced 4-nitro-2,4-diazabutanal (NDAB) also appeared to be active during transformation by whole cells of P. putida II-B and purified XenA. Both XenA and XenB also degraded the related nitramine explosives octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane. Purified XenB was found to have a broader substrate range than XenA, degrading more of the explosive compounds examined in this study. The results show that these two xenobiotic reductases (and their respective bacterial strains) have the capacity to transform RDX as well as a wide variety of explosive compounds, especially under low oxygen concentrations. PMID:19455327

  6. Metagenomic analysis of the pinewood nematode microbiome reveals a symbiotic relationship critical for xenobiotics degradation

    PubMed Central

    Cheng, Xin-Yue; Tian, Xue-Liang; Wang, Yun-Sheng; Lin, Ren-Miao; Mao, Zhen-Chuan; Chen, Nansheng; Xie, Bing-Yan

    2013-01-01

    Our recent research revealed that pinewood nematode (PWN) possesses few genes encoding enzymes for degrading α-pinene, which is the main compound in pine resin. In this study, we examined the role of PWN microbiome in xenobiotics detoxification by metagenomic and bacteria culture analyses. Functional annotation of metagenomes illustrated that benzoate degradation and its related metabolisms may provide the main metabolic pathways for xenobiotics detoxification in the microbiome, which is obviously different from that in PWN that uses cytochrome P450 metabolism as the main pathway for detoxification. The metabolic pathway of degrading α-pinene is complete in microbiome, but incomplete in PWN genome. Experimental analysis demonstrated that most of tested cultivable bacteria can not only survive the stress of 0.4% α-pinene, but also utilize α-pinene as carbon source for their growth. Our results indicate that PWN and its microbiome have established a potentially mutualistic symbiotic relationship with complementary pathways in detoxification metabolism. PMID:23694939

  7. COMPARISON OF MICROBIAL TRANSFORMATION RATE COEFFICIENTS OF XENOBIOTIC CHEMICALS BETWEEN FIELD-COLLECTED AND LABORATORY MICROCOSM MICROBIOTA

    EPA Science Inventory

    Two second-order transformation rate coefficients--kb, based on total plate counts, and kA, based on periphyton-colonized surface areas--were used to compare xenobiotic chemical transformation by laboratory-developed (microcosm) and by field-collected microbiota. Similarity of tr...

  8. 14 CFR 1267.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... workplace statement? 1267.205 Section 1267.205 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 1267.205 What must I include in my drug-free workplace statement? You...

  9. 13 CFR 147.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-free workplace statement? 147.205 Section 147.205 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (NONPROCUREMENT) Requirements for Recipients Other Than Individuals § 147.205 What must I include in my drug-free workplace statement? You must...

  10. A quantitative systems pharmacology approach, incorporating a novel liver model, for predicting pharmacokinetic drug-drug interactions.

    PubMed

    Cherkaoui-Rbati, Mohammed H; Paine, Stuart W; Littlewood, Peter; Rauch, Cyril

    2017-01-01

    All pharmaceutical companies are required to assess pharmacokinetic drug-drug interactions (DDIs) of new chemical entities (NCEs) and mathematical prediction helps to select the best NCE candidate with regard to adverse effects resulting from a DDI before any costly clinical studies. Most current models assume that the liver is a homogeneous organ where the majority of the metabolism occurs. However, the circulatory system of the liver has a complex hierarchical geometry which distributes xenobiotics throughout the organ. Nevertheless, the lobule (liver unit), located at the end of each branch, is composed of many sinusoids where the blood flow can vary and therefore creates heterogeneity (e.g. drug concentration, enzyme level). A liver model was constructed by describing the geometry of a lobule, where the blood velocity increases toward the central vein, and by modeling the exchange mechanisms between the blood and hepatocytes. Moreover, the three major DDI mechanisms of metabolic enzymes; competitive inhibition, mechanism based inhibition and induction, were accounted for with an undefined number of drugs and/or enzymes. The liver model was incorporated into a physiological-based pharmacokinetic (PBPK) model and simulations produced, that in turn were compared to ten clinical results. The liver model generated a hierarchy of 5 sinusoidal levels and estimated a blood volume of 283 mL and a cell density of 193 × 106 cells/g in the liver. The overall PBPK model predicted the pharmacokinetics of midazolam and the magnitude of the clinical DDI with perpetrator drug(s) including spatial and temporal enzyme levels changes. The model presented herein may reduce costs and the use of laboratory animals and give the opportunity to explore different clinical scenarios, which reduce the risk of adverse events, prior to costly human clinical studies.

  11. 28 CFR 83.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... workplace statement? 83.205 Section 83.205 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) GOVERNMENT-WIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (GRANTS) Requirements for Recipients Other Than Individuals § 83.205 What must I include in my drug-free workplace statement? You must publish a statement...

  12. 40 CFR 36.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... workplace statement? 36.205 Section 36.205 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 36.205 What must I include in my drug-free workplace...

  13. Transposable elements are enriched within or in close proximity to xenobiotic-metabolizing cytochrome P450 genes

    PubMed Central

    Chen, Song; Li, Xianchun

    2007-01-01

    Background Transposons, i.e. transposable elements (TEs), are the major internal spontaneous mutation agents for the variability of eukaryotic genomes. To address the general issue of whether transposons mediate genomic changes in environment-adaptation genes, we scanned two alleles per each of the six xenobiotic-metabolizing Helicoverpa zea cytochrome P450 loci, including CYP6B8, CYP6B27, CYP321A1, CYP321A2, CYP9A12v3 and CYP9A14, for the presence of transposon insertions by genome walking and sequence analysis. We also scanned thirteen Drosophila melanogaster P450s genes for TE insertions by in silico mapping and literature search. Results Twelve novel transposons, including LINEs (long interspersed nuclear elements), SINEs (short interspersed nuclear elements), MITEs (miniature inverted-repeat transposable elements), one full-length transib-like transposon, and one full-length Tcl-like DNA transpson, are identified from the alleles of the six H. zea P450 genes. The twelve transposons are inserted into the 5'flanking region, 3'flanking region, exon, or intron of the six environment-adaptation P450 genes. In D. melanogaster, seven out of the eight Drosophila P450s (CYP4E2, CYP6A2, CYP6A8, CYP6A9, CYP6G1, CYP6W1, CYP12A4, CYP12D1) implicated in insecticide resistance are associated with a variety of transposons. By contrast, all the five Drosophila P450s (CYP302A1, CYP306A1, CYP307A1, CYP314A1 and CYP315A1) involved in ecdysone biosynthesis and developmental regulation are free of TE insertions. Conclusion These results indicate that TEs are selectively retained within or in close proximity to xenobiotic-metabolizing P450 genes. PMID:17381843

  14. 10 CFR 607.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false What must I include in my drug-free workplace statement? 607.205 Section 607.205 Energy DEPARTMENT OF ENERGY (CONTINUED) ASSISTANCE REGULATIONS GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals...

  15. 34 CFR 84.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false What must I include in my drug-free workplace statement? 84.205 Section 84.205 Education Office of the Secretary, Department of Education GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals...

  16. 24 CFR 21.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... workplace statement? 21.205 Section 21.205 Housing and Urban Development Office of the Secretary, Department of Housing and Urban Development GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (GRANTS) Requirements for Recipients Other Than Individuals § 21.205 What must I include in my drug-free workplace...

  17. Biosynthesis of Drug Glucuronide Metabolites in the Budding Yeast Saccharomyces cerevisiae.

    PubMed

    Ikushiro, Shinichi; Nishikawa, Miyu; Masuyama, Yuuka; Shouji, Tadashi; Fujii, Miharu; Hamada, Masahiro; Nakajima, Noriyuki; Finel, Moshe; Yasuda, Kaori; Kamakura, Masaki; Sakaki, Toshiyuki

    2016-07-05

    Glucuronidation is one of the most common pathways in mammals for detoxification and elimination of hydrophobic xenobiotic compounds, including many drugs. Metabolites, however, can form active or toxic compounds, such as acyl glucuronides, and their safety assessment is often needed. The absence of efficient means for in vitro synthesis of correct glucuronide metabolites frequently limits such toxicological analyses. To overcome this hurdle we have developed a new approach, the essence of which is a coexpression system containing a human, or another mammalian UDP-glucuronosyltransferases (UGTs), as well as UDP-glucose-6-dehydrogenase (UGDH), within the budding yeast, Saccharomyces cerevisiae. The system was first tested using resting yeast cells coexpressing UGDH and human UGT1A6, 7-hydroxycoumarin as the substrate, in a reaction medium containing 8% glucose, serving as a source of UDP-glucuronic acid. Glucuronides were readily formed and recovered from the medium. Subsequently, by selecting suitable mammalian UGT enzyme for the coexpression system we could obtain the desired glucuronides of various compounds, including molecules with multiple conjugation sites and acyl glucuronides of several carboxylic acid containing drugs, namely, mefenamic acid, flufenamic acid, and zomepirac. In conclusion, a new and flexible yeast system with mammalian UGTs has been developed that exhibits a capacity for efficient production of various glucuronides, including acyl glucuronides.

  18. 31 CFR 20.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance: Treasury 1 2011-07-01 2011-07-01 false What must I include in my drug-free workplace statement? 20.205 Section 20.205 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for...

  19. 31 CFR 20.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false What must I include in my drug-free workplace statement? 20.205 Section 20.205 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for...

  20. 31 CFR 20.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance: Treasury 1 2014-07-01 2014-07-01 false What must I include in my drug-free workplace statement? 20.205 Section 20.205 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for...

  1. 31 CFR 20.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance: Treasury 1 2012-07-01 2012-07-01 false What must I include in my drug-free workplace statement? 20.205 Section 20.205 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for...

  2. 31 CFR 20.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance: Treasury 1 2013-07-01 2013-07-01 false What must I include in my drug-free workplace statement? 20.205 Section 20.205 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for...

  3. 43 CFR 43.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... workplace statement? 43.205 Section 43.205 Public Lands: Interior Office of the Secretary of the Interior GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 43.205 What must I include in my drug-free workplace statement? You must publish a statement...

  4. 15 CFR 29.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... workplace statement? 29.205 Section 29.205 Commerce and Foreign Trade Office of the Secretary of Commerce GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than Individuals § 29.205 What must I include in my drug-free workplace statement? You must publish a statement...

  5. 32 CFR 26.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 1 2010-07-01 2010-07-01 false What must I include in my drug-free workplace... DoD GRANT AND AGREEMENT REGULATIONS GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL... workplace statement? You must publish a statement that— (a) Tells your employees that the unlawful...

  6. Computational Identification of the Paralogs and Orthologs of Human Cytochrome P450 Superfamily and the Implication in Drug Discovery

    PubMed Central

    Pan, Shu-Ting; Xue, Danfeng; Li, Zhi-Ling; Zhou, Zhi-Wei; He, Zhi-Xu; Yang, Yinxue; Yang, Tianxin; Qiu, Jia-Xuan; Zhou, Shu-Feng

    2016-01-01

    The human cytochrome P450 (CYP) superfamily consisting of 57 functional genes is the most important group of Phase I drug metabolizing enzymes that oxidize a large number of xenobiotics and endogenous compounds, including therapeutic drugs and environmental toxicants. The CYP superfamily has been shown to expand itself through gene duplication, and some of them become pseudogenes due to gene mutations. Orthologs and paralogs are homologous genes resulting from speciation or duplication, respectively. To explore the evolutionary and functional relationships of human CYPs, we conducted this bioinformatic study to identify their corresponding paralogs, homologs, and orthologs. The functional implications and implications in drug discovery and evolutionary biology were then discussed. GeneCards and Ensembl were used to identify the paralogs of human CYPs. We have used a panel of online databases to identify the orthologs of human CYP genes: NCBI, Ensembl Compara, GeneCards, OMA (“Orthologous MAtrix”) Browser, PATHER, TreeFam, EggNOG, and Roundup. The results show that each human CYP has various numbers of paralogs and orthologs using GeneCards and Ensembl. For example, the paralogs of CYP2A6 include CYP2A7, 2A13, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, 2F1, 2J2, 2R1, 2S1, 2U1, and 2W1; CYP11A1 has 6 paralogs including CYP11B1, 11B2, 24A1, 27A1, 27B1, and 27C1; CYP51A1 has only three paralogs: CYP26A1, 26B1, and 26C1; while CYP20A1 has no paralog. The majority of human CYPs are well conserved from plants, amphibians, fishes, or mammals to humans due to their important functions in physiology and xenobiotic disposition. The data from different approaches are also cross-validated and validated when experimental data are available. These findings facilitate our understanding of the evolutionary relationships and functional implications of the human CYP superfamily in drug discovery. PMID:27367670

  7. Visualization of the Drosophila dKeap1-CncC interaction on chromatin illumines cooperative, xenobiotic-specific gene activation

    PubMed Central

    Deng, Huai; Kerppola, Tom K.

    2014-01-01

    Interactions among transcription factors control their physiological functions by regulating their binding specificities and transcriptional activities. We implement a strategy to visualize directly the genomic loci that are bound by multi-protein complexes in single cells in Drosophila. This method is based on bimolecular fluorescence complementation (BiFC) analysis of protein interactions on polytene chromosomes. Drosophila Keap1 (dKeap1)-CncC complexes localized to the nucleus and bound chromatin loci that were not bound preferentially by dKeap1 or CncC when they were expressed separately. dKeap1 and CncC binding at these loci was enhanced by phenobarbital, but not by tert-butylhydroquinone (tBHQ) or paraquat. Endogenous dKeap1 and CncC activated transcription of the Jheh (Jheh1, Jheh2, Jheh3) and dKeap1 genes at these loci, whereas CncC alone activated other xenobiotic response genes. Ectopic dKeap1 expression increased CncC binding at the Jheh and dKeap1 gene loci and activated their transcription, whereas dKeap1 inhibited CncC binding at other xenobiotic response gene loci and suppressed their transcription. The combinatorial chromatin-binding specificities and transcriptional activities of dKeap1-CncC complexes mediated the selective activation of different sets of genes by different xenobiotic compounds, in part through feed-forward activation of dKeap1 transcription. PMID:25063457

  8. ADAPTATION OF AQUIFER MICROBIAL COMMUNITIES TO THE BIODEGRADATION OF XENOBIOTIC COMPOUNDS: INFLUENCE OF SUBSTRATE CONCENTRATION AND PREEXPOSURE

    EPA Science Inventory

    Studies were conducted to examine the adaptation response of aquifer microbial communities to xenobiotic compounds and the influence of chemical preexposure in the laboratory and in situ on adaptation. Adaptation and biodegradation were assessed as mineralization and cellular inc...

  9. Interference with xenobiotic metabolic activity by the commonly used vehicle solvents dimethylsulfoxide and methanol in zebrafish (Danio rerio) larvae but not Daphnia magna

    PubMed Central

    David, Rhiannon M.; Jones, Huw S.; Panter, Grace H.; Winter, Matthew J.; Hutchinson, Thomas H.; Kevin Chipman, J.

    2012-01-01

    Organic solvents, such as dimethylsulfoxide (DMSO) and methanol are widely used as vehicles to solubilise lipophilic test compounds in toxicity testing. However, the effects of such solvents upon innate detoxification processes in aquatic organisms are poorly understood. This study assessed the effect of solvent exposure upon cytochrome P450 (CYP)-mediated xenobiotic metabolism in Daphnia magna and zebrafish larvae (4 d post fertilisation). Adult D. magna were demonstrated to have a low, but detectable, metabolism of ethoxyresorufin in vivo and this activity was not modulated by pre-exposure to DMSO or methanol (24 h, up to 0.1% and 0.05% v/v, respectively). In contrast, the metabolism of ethoxyresorufin in zebrafish larvae was significantly reduced by both solvents (0.1% and 0.05% v/v, respectively) after 24 h of exposure. In zebrafish, these observed decreases in activity towards ethoxyresorufin were accompanied by decreased expression of a variety of genes coding for drug metabolising enzymes (corresponding to CYP1, CYP2, CYP3 and UDP-glucuronyl transferase [UGT] family enzymes), measured by quantitative PCR. Reduction of gene expression and CYP1 enzyme activities by methanol (0.05% v/v) in zebrafish larvae was partially reversed by co-exposure with Aroclor 1254 (100 μg L−1). Overall this study suggests that relatively low concentrations of organic solvents can impact upon the biotransformation of certain xenobiotics in zebrafish larvae, and that this warrants consideration when assessing compounds for metabolism and toxicity in this species. PMID:22472102

  10. 31 CFR 20.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance: Treasury 1 2011-07-01 2011-07-01 false What must I include in my drug-free awareness program? 20.215 Section 20.215 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than...

  11. 31 CFR 20.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance: Treasury 1 2012-07-01 2012-07-01 false What must I include in my drug-free awareness program? 20.215 Section 20.215 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than...

  12. 31 CFR 20.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance: Treasury 1 2013-07-01 2013-07-01 false What must I include in my drug-free awareness program? 20.215 Section 20.215 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than...

  13. 31 CFR 20.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false What must I include in my drug-free awareness program? 20.215 Section 20.215 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than...

  14. 31 CFR 20.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance: Treasury 1 2014-07-01 2014-07-01 false What must I include in my drug-free awareness program? 20.215 Section 20.215 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Requirements for Recipients Other Than...

  15. Investigation of runoff generation from anthropogenic sources with dissolved xenobiotics

    NASA Astrophysics Data System (ADS)

    Krein, A.; Pailler, J.; Guignard, C.; Iffly, J.; Pfister, L.; Hoffmann, L.

    2009-04-01

    In the experimental Mess basin (35 km2, Luxembourg) dissolved xenobiotics in surface water are used to study the influences of anthropogenic sources like separated sewer systems on runoff generation. Emerging contaminants like pharmaceuticals are of growing interest because of their use in large quantities in human and veterinary medicine. The amounts reaching surface waters depend on rainfall patterns, hydraulic conditions, consumption, metabolism, degradation, and disposal. The behaviour of endocrine disruptors including pharmaceuticals in the aquatic environment is widely unknown. The twelve molecules analyzed belong to three families: the estrogens, the antibiotics (sulfonamides, tetracyclines), and the painkillers (ibuprofen, diclofenac). Xenobiotics can be used as potential environmental tracers for untreated sewerage. Our results show that the concentrations are highly variable during flood events. The highest concentrations are reached in the first flush period, mainly during the rising limb of the flood hydrographs. As a result of the kinematic wave effect the concentration peak occurs in some cases a few hours after the discharge maximum. In floodwater (eleven floods, 66 samples) the highest concentrations were measured for ibuprofen (g/l range), estrone, and diclofenac (all ng/l range). From the tetracycline group, essentially tetracycline itself is of relevance, while the sulfonamides are mainly represented by sulfamethoxazole (all in ng/l range). In the Mess River the pharmaceuticals fluxes during flood events proved to be influenced by hydrological conditions. Different pharmaceuticals showed their concentration peaks during different times of a flood event. An example is the estrone peak that - during summer flash floods - often occurred one to two hours prior to the largest concentrations of the painkillers. This suggests for more sources than the sole storm drainage through the spillway of the single sewage water treatment plant, different

  16. Cytochrome P450 peroxidase/peroxygenase mediated xenobiotic metabolic activation and cytotoxicity in isolated hepatocytes.

    PubMed

    Anari, M R; Khan, S; Liu, Z C; O'Brien, P J

    1995-12-01

    Cytochrome P450 (P450) can utilize organic hydroperoxides and peracids to support hydroxylation and dealkylation of various P450 substrates. However, the biological significance of this P450 peroxygenase/peroxidase activity in the bioactivation of xenobiotics in intact cells has not been demonstrated. We have shown that tert-butyl hydroperoxide (tBHP) markedly enhances 3-20-fold the cytotoxicity of various aromatic hydrocarbons and their phenolic metabolites. The tBHP-enhanced hepatocyte cytotoxicity of 4-nitroanisole (4-NA) and 4-hydroxyanisole (4-HA) was also accompanied by an increase in the hepatocyte O-demethylation of 4-NA and 4-HA up to 7.5- and 21-fold, respectively. Hepatocyte GSH conjugation by 4-HA was also markedly increased by tBHP. An LC/MS analysis of the GSH conjugates identified hydroquinone-GSH and 4-methoxy-catechol:GSH conjugates as the predominant adducts. Pretreatment of hepatocytes with P450 inhibitors, e.g., phenylimidazole, prevented tBHP-enhanced 4-HA metabolism, GSH depletion, and cytotoxicity. In conclusion, hydroperoxides can therefore be used by intact cells to support the bioactivation of xenobiotics through the P450 peroxidase/peroxygenase system.

  17. Development of an invitro technique to use mouse embryonic stem cell in evaluating effects of xenobiotics

    EPA Science Inventory

    Our goal has been to develop a high-throughput, in vitro technique for evaluating the effects of xenobiotics using mouse embryonic stem cells (mESCs). We began with the Embryonic Stem Cell Test (EST), which is used to predict the embryotoxic potential of a test compound by combin...

  18. Homologues of xenobiotic metabolizing N-acetyltransferases in plant-associated fungi: Novel functions for an old enzyme family

    USDA-ARS?s Scientific Manuscript database

    Plant-pathogenic fungi and their hosts engage in chemical warfare, attacking each other with toxic products of secondary metabolism and defending themselves via an arsenal of xenobiotic metabolizing enzymes. One such enzyme is homologous to arylamine N-acetyltransferase (NAT) and has been identified...

  19. A Liver-Centric Multiscale Modeling Framework for Xenobiotics.

    PubMed

    Sluka, James P; Fu, Xiao; Swat, Maciej; Belmonte, Julio M; Cosmanescu, Alin; Clendenon, Sherry G; Wambaugh, John F; Glazier, James A

    2016-01-01

    We describe a multi-scale, liver-centric in silico modeling framework for acetaminophen pharmacology and metabolism. We focus on a computational model to characterize whole body uptake and clearance, liver transport and phase I and phase II metabolism. We do this by incorporating sub-models that span three scales; Physiologically Based Pharmacokinetic (PBPK) modeling of acetaminophen uptake and distribution at the whole body level, cell and blood flow modeling at the tissue/organ level and metabolism at the sub-cellular level. We have used standard modeling modalities at each of the three scales. In particular, we have used the Systems Biology Markup Language (SBML) to create both the whole-body and sub-cellular scales. Our modeling approach allows us to run the individual sub-models separately and allows us to easily exchange models at a particular scale without the need to extensively rework the sub-models at other scales. In addition, the use of SBML greatly facilitates the inclusion of biological annotations directly in the model code. The model was calibrated using human in vivo data for acetaminophen and its sulfate and glucuronate metabolites. We then carried out extensive parameter sensitivity studies including the pairwise interaction of parameters. We also simulated population variation of exposure and sensitivity to acetaminophen. Our modeling framework can be extended to the prediction of liver toxicity following acetaminophen overdose, or used as a general purpose pharmacokinetic model for xenobiotics.

  20. A Liver-Centric Multiscale Modeling Framework for Xenobiotics

    PubMed Central

    Swat, Maciej; Cosmanescu, Alin; Clendenon, Sherry G.; Wambaugh, John F.; Glazier, James A.

    2016-01-01

    We describe a multi-scale, liver-centric in silico modeling framework for acetaminophen pharmacology and metabolism. We focus on a computational model to characterize whole body uptake and clearance, liver transport and phase I and phase II metabolism. We do this by incorporating sub-models that span three scales; Physiologically Based Pharmacokinetic (PBPK) modeling of acetaminophen uptake and distribution at the whole body level, cell and blood flow modeling at the tissue/organ level and metabolism at the sub-cellular level. We have used standard modeling modalities at each of the three scales. In particular, we have used the Systems Biology Markup Language (SBML) to create both the whole-body and sub-cellular scales. Our modeling approach allows us to run the individual sub-models separately and allows us to easily exchange models at a particular scale without the need to extensively rework the sub-models at other scales. In addition, the use of SBML greatly facilitates the inclusion of biological annotations directly in the model code. The model was calibrated using human in vivo data for acetaminophen and its sulfate and glucuronate metabolites. We then carried out extensive parameter sensitivity studies including the pairwise interaction of parameters. We also simulated population variation of exposure and sensitivity to acetaminophen. Our modeling framework can be extended to the prediction of liver toxicity following acetaminophen overdose, or used as a general purpose pharmacokinetic model for xenobiotics. PMID:27636091

  1. Fatty liver and drugs: the two sides of the same coin.

    PubMed

    Miele, L; Liguori, A; Marrone, G; Biolato, M; Araneo, C; Vaccaro, F G; Gasbarrini, A; Grieco, A

    2017-03-01

    Drug-induced liver injury (DILI) is a common and underestimated cause of liver disease. Several drugs and other xenobiotics can be the cause of different clinicopathologic patterns of liver disease. Steatosis and steatohepatitis are rare but well-documented types of DILI. Over the past decades commonly used drugs like amiodarone, tamoxifen, irinotecan, methotrexate, valproic acid and glucocorticoids have been recognized to be associated with steatosis. Even though the pathophysiological pathways are still only partially understood, inhibition of mitochondrial beta-oxidation, reduced very low-density lipoprotein secretion, insulin resistance induction and increased de novo synthesis or increased liver uptake of fatty acids are considered the main pathogenic mechanisms through which drugs can lead to hepatic steatosis. On the other hand, fatty liver itself is a very common clinical condition, and there is a growing awareness of the potential risk factors for DILI due to the underlying metabolic condition itself.

  2. Oxidation and adduct formation of xenobiotics in a microfluidic electrochemical cell with boron doped diamond electrodes and an integrated passive gradient rotation mixer.

    PubMed

    van den Brink, Floris T G; Wigger, Tina; Ma, Liwei; Odijk, Mathieu; Olthuis, Wouter; Karst, Uwe; van den Berg, Albert

    2016-10-05

    Reactive xenobiotic metabolites and their adduct formation with biomolecules such as proteins are important to study as they can be detrimental to human health. Here, we present a microfluidic electrochemical cell with integrated micromixer to study phase I and phase II metabolism as well as protein adduct formation of xenobiotics in a purely instrumental approach. The newly developed microfluidic device enables both the generation of reactive metabolites through electrochemical oxidation and subsequent adduct formation with biomolecules in a chemical microreactor. This allows us to study the detoxification of reactive species with glutathione and to predict potential toxicity of xenobiotics as a result of protein modification. Efficient mixing in microfluidic systems is a slow process due to the typically laminar flow conditions in shallow channels. Therefore, a passive gradient rotation micromixer has been designed that is capable of mixing liquids efficiently in a 790 pL volume within tens of milliseconds. The mixing principle relies on turning the concentration gradient that is initially established by bringing together two streams of liquid, to take advantage of the short diffusion distances in the shallow microchannels of thin-layer flow cells. The mixer is located immediately downstream of the working electrode of an electrochemical cell with integrated boron doped diamond electrodes. In conjunction with mass spectrometry, the two microreactors integrated in a single device provide a powerful tool to study the metabolism and toxicity of xenobiotics, which was demonstrated by the investigation of the model compound 1-hydroxypyrene.

  3. Insights into drug metabolism by cytochromes P450 from modelling studies of CYP2D6-drug interactions

    PubMed Central

    Maréchal, J-D; Kemp, C A; Roberts, G C K; Paine, M J I; Wolf, C R; Sutcliffe, M J

    2008-01-01

    The cytochromes P450 (CYPs) comprise a vast superfamily of enzymes found in virtually all life forms. In mammals, xenobiotic metabolizing CYPs provide crucial protection from the effects of exposure to a wide variety of chemicals, including environmental toxins and therapeutic drugs. Ideally, the information on the possible metabolism by CYPs required during drug development would be obtained from crystal structures of all the CYPs of interest. For some years only crystal structures of distantly related bacterial CYPs were available and homology modelling techniques were used to bridge the gap and produce structural models of human CYPs, and thereby obtain useful functional information. A significant step forward in the reliability of these models came seven years ago with the first crystal structure of a mammalian CYP, rabbit CYP2C5, followed by the structures of six human enzymes, CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2D6 and CYP3A4, and a second rabbit enzyme, CYP2B4. In this review we describe as a case study the evolution of a CYP2D6 model, leading to the validation of the model as an in silico tool for predicting binding and metabolism. This work has led directly to the successful design of CYP2D6 mutants with novel activity—including creating a testosterone hydroxylase, converting quinidine from inhibitor to substrate, creating a diclofenac hydroxylase and creating a dextromethorphan O-demethylase. Our modelling-derived hypothesis-driven integrated interdisciplinary studies have given key insight into the molecular determinants of CYP2D6 and other important drug metabolizing enzymes. PMID:18026129

  4. Functioning of Microsomal Cytochrome P450s: Murburn Concept Explains the Metabolism of Xenobiotics in Hepatocytes.

    PubMed

    Manoj, Kelath Murali; Parashar, Abhinav; Gade, Sudeep K; Venkatachalam, Avanthika

    2016-01-01

    Using oxygen and NADPH, the redox enzymes cytochrome P450 (CYP) and its reductase (CPR) work in tandem to carry out the phase I metabolism of a vast majority of drugs and xenobiotics. As per the erstwhile understanding of the catalytic cycle, binding of the substrate to CYP's heme distal pocket allows CPR to pump electrons through a CPR-CYP complex. In turn, this trigger (a thermodynamic push of electrons) leads to the activation of oxygen at CYP's heme-center, to give Compound I, a two-electron deficient enzyme reactive intermediate. The formation of diffusible radicals and reactive oxygen species (DROS, hitherto considered an undesired facet of the system) was attributed to the heme-center. Recently, we had challenged these perceptions and proposed the murburn ("mured burning" or "mild unrestricted burning") concept to explain heme enzymes' catalytic mechanism, electron-transfer phenomena and the regulation of redox equivalents' consumption. Murburn concept incorporates a one-electron paradigm, advocating obligatory roles for DROS. The new understanding does not call for high-affinity substrate-binding at the heme distal pocket of the CYP (the first and the most crucial step of the erstwhile paradigm) or CYP-CPR protein-protein complexations (the operational backbone of the erstwhile cycle). Herein, the dynamics of reduced nicotinamide nucleotides' consumption, peroxide formation and depletion, product(s) formation, etc. was investigated with various controls, by altering reaction variables, environments and through the incorporation of diverse molecular probes. In several CYP systems, control reactions lacking the specific substrate showed comparable or higher peroxide in milieu, thereby discrediting the foundations of the erstwhile hypothesis. The profiles obtained by altering CYP:CPR ratios and the profound inhibitions observed upon the incorporation of catalytic amounts of horseradish peroxidase confirm the obligatory roles of DROS in milieu, ratifying

  5. Comparative genomic, phylogenetic, and functional investigation of the xenobiotic metabolizing arylamine N-acetyltransferase enzyme family among fungi

    USDA-ARS?s Scientific Manuscript database

    Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes well-characterized in several bacteria and higher eukaryotes. The role of NATs in fungal biology has only recently been investigated (Glenn and Bacon, 2009; Glenn et al., 2010). The NAT1 gene of Gibberella moniliformis was the...

  6. Optimized laser-induced breakdown spectroscopy for determination of xenobiotic silver in monosodium glutamate and its verification using ICP-AES.

    PubMed

    Rehan, I; Gondal, M A; Rehan, K

    2018-04-20

    Laser-induced breakdown spectroscopy (LIBS) was applied as a potential tool for the determination of xenobiotic metal in monosodium glutamate (MSG). In order to achieve a high-sensitivity LIBS system required to determine trace amounts of metallic silver in MSG and to attain the best detection limit, the parameters used in our experiment (impact of focusing laser energy on the intensity of LIBS emission signals, the influence of focusing lens distance on the intensity of LIBS signals, and time responses of the plasma emissions) were optimized. The spectra of MSG were obtained in air using a suitable detector with an optical resolution of 0.06 nm, covering a spectral region from 220 to 720 nm. Along with the detection of xenobiotic silver, other elements such as Ca, Mg, S, and Na were also detected in MSG. To determine the concentration of xenobiotic silver in MSG, the calibration curve was plotted by preparing standard samples having different silver abundances in an MSG matrix. The LIBS results of each sample were cross-verified by analyzing with a standard analytical technique such as inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Both (LIBS and ICP-AES) results were in mutual agreement. The limit of detection of the LIBS setup was found to be 0.57 ppm for silver present in MSG samples.

  7. Adaptation to environmental stress in Daphnia magna simultaneously exposed to a xenobiotic.

    PubMed

    Coors, Anja; Hammers-Wirtz, Monika; Ratte, Hans Toni

    2004-07-01

    In standardized ecotoxicological testing chemicals are investigated under optimal conditions for the test organisms despite the fact that environmental factors such as predation pressure and food availability are important parameters regulating natural populations. Food limitation and predator presence can induce shifts in life-history traits in various Daphnia species, especially trade-offs in reproductive biomass allocation. These adaptive responses are thought to ensure survival of the population in a highly variable environment. A xenobiotic dispersant (used in textile dyeing processes) also shifted the biomass allocation of Daphnia magna. To assess whether the dispersant could hinder D. magna adaptation to varying environmental conditions, we conducted experiments with food level and presence of Chaoborus larvae as environmental factors and simultaneous exposure to the dispersant. At low food level and in presence of the predator, D. magna produced fewer but larger sized neonates, regardless of dispersant exposure. The dispersant shifted biomass allocation towards more but smaller sized offspring in all experiments. However, the adaptive response to the environmental factors and the dispersant effect cancelled each other out in that they induced independently from each other opposite shifts in biomass allocation. In summary, the dispersant exposure resulted not in an inhibition of the adaptive response but in a reduction of the value of the response. Our study with this model substance demonstrates that xenobiotics can affect the adaptation of organisms to environmental stress which can result in effects likely to be overlooked in standardized testing.

  8. Cytochrome P450 enzyme mediated herbal drug interactions (Part 1)

    PubMed Central

    Wanwimolruk, Sompon; Prachayasittikul, Virapong

    2014-01-01

    It is well recognized that herbal supplements or herbal medicines are now commonly used. As many patients taking prescription medications are concomitantly using herbal supplements, there is considerable risk for adverse herbal drug interactions. Such interactions can enhance the risk for an individual patient, especially with regard to drugs with a narrow therapeutic index such as warfarin, cyclosporine A and digoxin. Herbal drug interactions can alter pharmacokinetic or/and pharmacodynamic properties of administered drugs. The most common pharmacokinetic interactions usually involve either the inhibition or induction of the metabolism of drugs catalyzed by the important enzymes, cytochrome P450 (CYP). The aim of the present article is to provide an updated review of clinically relevant metabolic CYP-mediated drug interactions between selected herbal supplements and prescription drugs. The commonly used herbal supplements selected include Echinacea, Ginkgo biloba, garlic, St. John's wort, goldenseal, and milk thistle. To date, several significant herbal drug interactions have their origins in the alteration of CYP enzyme activity by various phytochemicals. Numerous herbal drug interactions have been reported. Although the significance of many interactions is uncertain but several interactions, especially those with St. John’s wort, may have critical clinical consequences. St. John’s wort is a source of hyperforin, an active ingredient that has a strong affinity for the pregnane xenobiotic receptor (PXR). As a PXR ligand, hyperforin promotes expression of CYP3A4 enzymes in the small intestine and liver. This in turn causes induction of CYP3A4 and can reduce the oral bioavailability of many drugs making them less effective. The available evidence indicates that, at commonly recommended doses, other selected herbs including Echinacea, Ginkgo biloba, garlic, goldenseal and milk thistle do not act as potent or moderate inhibitors or inducers of CYP enzymes. A good

  9. Natural allelic variations of xenobiotic-metabolizing enzymes affect sexual dimorphism in Oryzias latipes.

    PubMed

    Katsumura, Takafumi; Oda, Shoji; Nakagome, Shigeki; Hanihara, Tsunehiko; Kataoka, Hiroshi; Mitani, Hiroshi; Kawamura, Shoji; Oota, Hiroki

    2014-12-22

    Sexual dimorphisms, which are phenotypic differences between males and females, are driven by sexual selection. Interestingly, sexually selected traits show geographical variations within species despite strong directional selective pressures. This paradox has eluded many evolutionary biologists for some time, and several models have been proposed (e.g. 'indicator model' and 'trade-off model'). However, disentangling which of these theories explains empirical patterns remains difficult, because genetic polymorphisms that cause variation in sexual differences are still unknown. In this study, we show that polymorphisms in cytochrome P450 (CYP) 1B1, which encodes a xenobiotic-metabolizing enzyme, are associated with geographical differences in sexual dimorphism in the anal fin morphology of medaka fish (Oryzias latipes). Biochemical assays and genetic cross experiments show that high- and low-activity CYP1B1 alleles enhanced and declined sex differences in anal fin shapes, respectively. Behavioural and phylogenetic analyses suggest maintenance of the high-activity allele by sexual selection, whereas the low-activity allele possibly has experienced positive selection due to by-product effects of CYP1B1 in inferred ancestral populations. The present data can elucidate evolutionary mechanisms behind genetic variations in sexual dimorphism and indicate trade-off interactions between two distinct mechanisms acting on the two alleles with pleiotropic effects of xenobiotic-metabolizing enzymes. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  10. In Silico Prediction of Cytochrome P450-Mediated Biotransformations of Xenobiotics: A Case Study of Epoxidation.

    PubMed

    Zhang, Jing; Ji, Li; Liu, Weiping

    2015-08-17

    Predicting the biotransformation of xenobiotics is important in toxicology; however, as more compounds are synthesized than can be investigated experimentally, powerful computational methods are urgently needed to prescreen potentially useful candidates. Cytochrome P450 enzymes (P450s) are the major enzymes involved in xenobiotic metabolism, and many substances are bioactivated by P450s to form active compounds. An example is the conversion of olefinic substrates to epoxides, which are intermediates in the metabolic activation of many known or suspected carcinogens. We have calculated the activation energies for epoxidation by the active species of P450 enzymes (an iron-oxo porphyrin cation radical oxidant, compound I) for a diverse set of 36 olefinic substrates with state-of-the-art density functional theory (DFT) methods. Activation energies can be estimated by the computationally less demanding method of calculating the ionization potentials of the substrates, which provides a useful and simple predictive model based on the reaction mechanism; however, the preclassification of these diverse substrates into weakly polar and strongly polar groups is a prerequisite for the construction of specific predictive models with good predictability for P450 epoxidation. This approach has been supported by both internal and external validations. Furthermore, the relation between the activation energies for the regioselective epoxidation and hydroxylation reactions of P450s and experimental data has been investigated. The results show that the computational method used in this work, single-point energy calculations with the B3LYP functional including zero-point energy and solvation and dispersion corrections based on B3LYP-optimized geometries, performs well in reproducing the experimental trends of the epoxidation and hydroxylation reactions.

  11. Targeting blood–brain barrier changes during inflammatory pain: an opportunity for optimizing CNS drug delivery

    PubMed Central

    Ronaldson, Patrick T; Davis, Thomas P

    2012-01-01

    The blood–brain barrier (BBB) is the most significant obstacle to effective CNS drug delivery. It possesses structural and biochemical features (i.e., tight-junction protein complexes and, influx and efflux transporters) that restrict xenobiotic permeation. Pathophysiological stressors (i.e., peripheral inflammatory pain) can alter BBB tight junctions and transporters, which leads to drug-permeation changes. This is especially critical for opioids, which require precise CNS concentrations to be safe and effective analgesics. Recent studies have identified molecular targets (i.e., endogenous transporters and intracellular signaling systems) that can be exploited for optimization of CNS drug delivery. This article summarizes current knowledge in this area and emphasizes those targets that present the greatest opportunity for controlling drug permeation and/or drug transport across the BBB in an effort to achieve optimal CNS opioid delivery. PMID:22468221

  12. Drug Abuse Education Program. Drug Abuse Education, Grades 5,7,9. Bibliography Included.

    ERIC Educational Resources Information Center

    Baltimore City Public Schools, MD.

    A drug abuse education program was implemented in grades five, seven, and nine in the Baltimore City Public Schools. Unit plans outline the curriculum content and learning activities for each of the three grades. The major objective in grade five is to familiarize pupils with various medically used drugs and to develop an understanding that they…

  13. Interactions between Human Liver Fatty Acid Binding Protein and Peroxisome Proliferator Activated Receptor Selective Drugs

    PubMed Central

    Velkov, Tony

    2013-01-01

    Fatty acid binding proteins (FABPs) act as intracellular shuttles for fatty acids as well as lipophilic xenobiotics to the nucleus, where these ligands are released to a group of nuclear receptors called the peroxisome proliferator activated receptors (PPARs). PPAR mediated gene activation is ultimately involved in maintenance of cellular homeostasis through the transcriptional regulation of metabolic enzymes and transporters that target the activating ligand. Here we show that liver- (L-) FABP displays a high binding affinity for PPAR subtype selective drugs. NMR chemical shift perturbation mapping and proteolytic protection experiments show that the binding of the PPAR subtype selective drugs produces conformational changes that stabilize the portal region of L-FABP. NMR chemical shift perturbation studies also revealed that L-FABP can form a complex with the PPAR ligand binding domain (LBD) of PPARα. This protein-protein interaction may represent a mechanism for facilitating the activation of PPAR transcriptional activity via the direct channeling of ligands between the binding pocket of L-FABP and the PPARαLBD. The role of L-FABP in the delivery of ligands directly to PPARα via this channeling mechanism has important implications for regulatory pathways that mediate xenobiotic responses and host protection in tissues such as the small intestine and the liver where L-FABP is highly expressed. PMID:23476633

  14. Xenobiotic-metabolizing enzymes in the skin of rat, mouse, pig, guinea pig, man, and in human skin models.

    PubMed

    Oesch, F; Fabian, E; Guth, K; Landsiedel, R

    2014-12-01

    The exposure of the skin to medical drugs, skin care products, cosmetics, and other chemicals renders information on xenobiotic-metabolizing enzymes (XME) in the skin highly interesting. Since the use of freshly excised human skin for experimental investigations meets with ethical and practical limitations, information on XME in models comes in the focus including non-human mammalian species and in vitro skin models. This review attempts to summarize the information available in the open scientific literature on XME in the skin of human, rat, mouse, guinea pig, and pig as well as human primary skin cells, human cell lines, and reconstructed human skin models. The most salient outcome is that much more research on cutaneous XME is needed for solid metabolism-dependent efficacy and safety predictions, and the cutaneous metabolism comparisons have to be viewed with caution. Keeping this fully in mind at least with respect to some cutaneous XME, some models may tentatively be considered to approximate reasonable closeness to human skin. For dermal absorption and for skin irritation among many contributing XME, esterase activity is of special importance, which in pig skin, some human cell lines, and reconstructed skin models appears reasonably close to human skin. With respect to genotoxicity and sensitization, activating XME are not yet judgeable, but reactive metabolite-reducing XME in primary human keratinocytes and several reconstructed human skin models appear reasonably close to human skin. For a more detailed delineation and discussion of the severe limitations see the "Overview and Conclusions" section in the end of this review.

  15. Cunninghamella Biotransformation--Similarities to Human Drug Metabolism and Its Relevance for the Drug Discovery Process.

    PubMed

    Piska, Kamil; Żelaszczyk, Dorota; Jamrozik, Marek; Kubowicz-Kwaśny, Paulina; Pękala, Elżbieta

    2016-01-01

    Studies of drug metabolism are one of the most significant issues in the process of drug development, its introduction to the market and also in treatment. Even the most promising molecule may show undesirable metabolic properties that would disqualify it as a potential drug. Therefore, such studies are conducted in the early phases of drug discovery and development process. Cunninghamella is a filamentous fungus known for its catalytic properties, which mimics mammalian drug metabolism. It has been proven that C. elegans carries at least one gene coding for a CYP enzyme closely related to the CYP51 family. The transformation profile of xenobiotics in Cunninghamella spp. spans a number of reactions catalyzed by different mammalian CYP isoforms. This paper presents detailed data on similar biotransformation drug products in humans and Cunninghamella spp. and covers the most important aspects of preparative biosynthesis of metabolites, since this model allows to obtain metabolites in sufficient quantities to conduct the further detailed investigations, as quantification, structure analysis and pharmacological activity and toxicity testing. The metabolic activity of three mostly used Cunninghamella species in obtaining hydroxylated, dealkylated and oxidated metabolites of different drugs confirmed its convergence with human biotransformation. Though it cannot replace the standard methods, it can provide support in the field of biotransformation and identifying metabolic soft spots of new chemicals and in predicting possible metabolic pathways. Another aspect is the biosynthesis of metabolites. In this respect, techniques using Cunninghamella spp. seem to be competitive to the chemical methods currently used.

  16. Feed-drug interaction of orally applied butyrate and phenobarbital on hepatic cytochrome P450 activity in chickens.

    PubMed

    Mátis, G; Kulcsár, A; Petrilla, J; Hermándy-Berencz, K; Neogrády, Zs

    2016-08-01

    The expression of hepatic drug-metabolizing cytochrome P450 (CYP) enzymes may be affected by several nutrition-derived compounds, such as by the commonly applied feed additive butyrate, possibly leading to feed-drug interactions. The aim of this study was to provide some evidence if butyrate can alter the activity of hepatic CYPs in chickens exposed to CYP-inducing xenobiotics, monitoring for the first time the possibility of such interaction. Ross 308 chickens in the grower phase were treated with daily intracoelomal phenobarbital (PB) injection (80 mg/kg BW), applied as a non-specific CYP-inducer, simultaneously with two different doses of intra-ingluvial sodium butyrate boluses (0.25 and 1.25 g/kg BW) for 5 days. Activity of CYP2H and CYP3A subfamilies was assessed by specific enzyme assays from isolated liver microsomes. According to our results, the lower dose of orally administered butyrate significantly attenuated the PB-triggered elevation of both hepatic CYP2H and CYP3A activities, which might be in association with the partly common signalling pathways of butyrate and CYP-inducing drugs, such as that of PB. Based on these data, butyrate may take part in pharmacoepigenetic interactions with simultaneously applied drugs or other CYP-inducing xenobiotics, with possible consequences for food safety and pharmacotherapy. Butyrate was found to be capable to maintain physiological CYP activity by attenuating CYP induction, underlining the safety of butyrate application in poultry nutrition. Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

  17. A Compilation of In Vitro Rate and Affinity Values for Xenobiotic Biotransformation in Fish, Measured Under Physiological Conditions

    EPA Science Inventory

    This manuscript presents a summary of in vitro rate and affinity data for xenobiotic biotransformation enzymes in fish...One potential use of this data summary is to support in vitro to in vivo metabolism extrapolations which can be used as inputs to chemical kinetic models for f...

  18. Selection of Reference Genes for Expression Studies of Xenobiotic Adaptation in Tetranychus urticae.

    PubMed

    Morales, Mariany Ashanty; Mendoza, Bianca Marie; Lavine, Laura Corley; Lavine, Mark Daniel; Walsh, Douglas Bruce; Zhu, Fang

    2016-01-01

    Quantitative real-time PCR (qRT-PCR) is an extensively used, high-throughput method to analyze transcriptional expression of genes of interest. An appropriate normalization strategy with reliable reference genes is required for calculating gene expression across diverse experimental conditions. In this study, we aim to identify the most stable reference genes for expression studies of xenobiotic adaptation in Tetranychus urticae, an extremely polyphagous herbivore causing significant yield reduction of agriculture. We chose eight commonly used housekeeping genes as candidates. The qRT-PCR expression data for these genes were evaluated from seven populations: a susceptible and three acaricide resistant populations feeding on lima beans, and three other susceptible populations which had been shifted host from lima beans to three other plant species. The stability of the candidate reference genes was then assessed using four different algorithms (comparative ΔCt method, geNorm, NormFinder, and BestKeeper). Additionally, we used an online web-based tool (RefFinder) to assign an overall final rank for each candidate gene. Our study found that CycA and Rp49 are best for investigating gene expression in acaricide susceptible and resistant populations. GAPDH, Rp49, and Rpl18 are best for host plant shift studies. And GAPDH and Rp49 were the most stable reference genes when investigating gene expression under changes in both experimental conditions. These results will facilitate research in revealing molecular mechanisms underlying the xenobiotic adaptation of this notorious agricultural pest.

  19. Selection of Reference Genes for Expression Studies of Xenobiotic Adaptation in Tetranychus urticae

    PubMed Central

    Morales, Mariany Ashanty; Mendoza, Bianca Marie; Lavine, Laura Corley; Lavine, Mark Daniel; Walsh, Douglas Bruce; Zhu, Fang

    2016-01-01

    Quantitative real-time PCR (qRT-PCR) is an extensively used, high-throughput method to analyze transcriptional expression of genes of interest. An appropriate normalization strategy with reliable reference genes is required for calculating gene expression across diverse experimental conditions. In this study, we aim to identify the most stable reference genes for expression studies of xenobiotic adaptation in Tetranychus urticae, an extremely polyphagous herbivore causing significant yield reduction of agriculture. We chose eight commonly used housekeeping genes as candidates. The qRT-PCR expression data for these genes were evaluated from seven populations: a susceptible and three acaricide resistant populations feeding on lima beans, and three other susceptible populations which had been shifted host from lima beans to three other plant species. The stability of the candidate reference genes was then assessed using four different algorithms (comparative ΔCt method, geNorm, NormFinder, and BestKeeper). Additionally, we used an online web-based tool (RefFinder) to assign an overall final rank for each candidate gene. Our study found that CycA and Rp49 are best for investigating gene expression in acaricide susceptible and resistant populations. GAPDH, Rp49, and Rpl18 are best for host plant shift studies. And GAPDH and Rp49 were the most stable reference genes when investigating gene expression under changes in both experimental conditions. These results will facilitate research in revealing molecular mechanisms underlying the xenobiotic adaptation of this notorious agricultural pest. PMID:27570487

  20. The human orphan nuclear receptor PXR is activated by compounds that regulate CYP3A4 gene expression and cause drug interactions.

    PubMed Central

    Lehmann, J M; McKee, D D; Watson, M A; Willson, T M; Moore, J T; Kliewer, S A

    1998-01-01

    The cytochrome P-450 monooxygenase 3A4 (CYP3A4) is responsible for the oxidative metabolism of a wide variety of xenobiotics including an estimated 60% of all clinically used drugs. Although expression of the CYP3A4 gene is known to be induced in response to a variety of compounds, the mechanism underlying this induction, which represents a basis for drug interactions in patients, has remained unclear. We report the identification of a human (h) orphan nuclear receptor, termed the pregnane X receptor (PXR), that binds to a response element in the CYP3A4 promoter and is activated by a range of drugs known to induce CYP3A4 expression. Comparison of hPXR with the recently cloned mouse PXR reveals marked differences in their activation by certain drugs, which may account in part for the species-specific effects of compounds on CYP3A gene expression. These findings provide a molecular explanation for the ability of disparate chemicals to induce CYP3A4 levels and, furthermore, provide a basis for developing in vitro assays to aid in predicting whether drugs will interact in humans. PMID:9727070

  1. 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

  2. Xenobiotic Compounds Degradation by Heterologous Expression of a Trametes sanguineus Laccase in Trichoderma atroviride

    PubMed Central

    Balcázar-López, Edgar; Méndez-Lorenzo, Luz Helena; Batista-García, Ramón Alberto; Esquivel-Naranjo, Ulises; Ayala, Marcela; Kumar, Vaidyanathan Vinoth; Savary, Olivier; Cabana, Hubert; Herrera-Estrella, Alfredo; Folch-Mallol, Jorge Luis

    2016-01-01

    Fungal laccases are enzymes that have been studied because of their ability to decolorize and detoxify effluents; they are also used in paper bleaching, synthesis of polymers, bioremediation, etc. In this work we were able to express a laccase from Trametes (Pycnoporus) sanguineus in the filamentous fungus Trichoderma atroviride. For this purpose, a transformation vector was designed to integrate the gene of interest in an intergenic locus near the blu17 terminator region. Although monosporic selection was still necessary, stable integration at the desired locus was achieved. The native signal peptide from T. sanguineus laccase was successful to secrete the recombinant protein into the culture medium. The purified, heterologously expressed laccase maintained similar properties to those observed in the native enzyme (Km and kcat and kcat/km values for ABTS, thermostability, substrate range, pH optimum, etc). To determine the bioremediation potential of this modified strain, the laccase-overexpressing Trichoderma strain was used to remove xenobiotic compounds. Phenolic compounds present in industrial wastewater and bisphenol A (an endocrine disruptor) from the culture medium were more efficiently removed by this modified strain than with the wild type. In addition, the heterologously expressed laccase was able to decolorize different dyes as well as remove benzo[α]pyrene and phenanthrene in vitro, showing its potential for xenobiotic compound degradation. PMID:26849129

  3. Classification and modelling of non-extractable residue (NER) formation from xenobiotics in soil - a synthesis

    NASA Astrophysics Data System (ADS)

    Kaestner, Matthias; Nowak, Karolina; Miltner, Anja; Trapp, Stefan; Schaeffer, Andreas

    2014-05-01

    This presentation provides a comprehensive overview about the formation of non-extractable residues (NER) from organic pesticides and contaminants in soil and tries classifying the different types. Anthropogenic organic chemicals are deliberately (e.g. pesticides) or unintentionally (e.g. polyaromatic hydrocarbons [PAH], chlorinated solvents, pharmaceuticals) released in major amounts to nearly all compartments of the environment. Soils and sediments as complex matrices provide a wide variety of binding sites and are the major sinks for these compounds. Many of the xenobiotics entering soil undergo turnover processes and can be volatilised, leached to the groundwater, degraded by microorganisms or taken up and enriched by living organisms. Xenobiotic NER may be derived from parent compounds and primary metabolites that are sequestered (sorbed or entrapped) within the soil organic matter (type I NER) or can be covalently bound (type II NER). Especially type I NER may pose a considerably environmental risk of potential release. However, NER resulting from productive biodegradation, which means the conversion of carbon (or nitrogen) from the compounds into microbial biomass molecules during microbial degradation (type III, bioNER), do not pose any risk. Experimental and analytical approaches to clearly distinguish between the types are provided and a model to prospectively estimate their fate in soil is proposed.

  4. Molecular cloning of a family of xenobiotic-inducible drosophilid cytochrome P450s: Evidence for involvement in host-plant allelochemical resistance

    PubMed Central

    Danielson, Phillip B.; MacIntyre, Ross J.; Fogleman, James C.

    1997-01-01

    Cytochrome P450s constitute a superfamily of genes encoding mostly microsomal hemoproteins that play a dominant role in the metabolism of a wide variety of both endogenous and foreign compounds. In insects, xenobiotic metabolism (i.e., metabolism of insecticides and toxic natural plant compounds) is known to involve members of the CYP6 family of cytochrome P450s. Use of a 3′ RACE (rapid amplification of cDNA ends) strategy with a degenerate primer based on the conserved cytochrome P450 heme-binding decapeptide loop resulted in the amplification of four cDNA sequences representing another family of cytochrome P450 genes (CYP28) from two species of isoquinoline alkaloid-resistant Drosophila and the cosmopolitan species Drosophila hydei. The CYP28 family forms a monophyletic clade with strong regional homologies to the vertebrate CYP3 family and the insect CYP6 family (both of which are involved in xenobiotic metabolism) and to the insect CYP9 family (of unknown function). Induction of mRNA levels for three of the CYP28 cytochrome P450s by toxic host-plant allelochemicals (up to 11.5-fold) and phenobarbital (up to 49-fold) corroborates previous in vitro metabolism studies and suggests a potentially important role for the CYP28 family in determining patterns of insect–host-plant relationships through xenobiotic detoxification. PMID:9380713

  5. Environmental Factors and Bioremediation of Xenobiotics Using White Rot Fungi

    PubMed Central

    Fragoeiro, Silvia; Bastos, Catarina

    2010-01-01

    This review provides background information on the importance of bioremediation approaches. It describes the roles of fungi, specifically white rot fungi, and their extracellular enzymes, laccases, ligninases, and peroxidises, in the degradation of xenobiotic compounds such as single and mixtures of pesticides. We discuss the importance of abiotic factors such as water potential, temperature, and pH stress when considering an environmental screening approach, and examples are provided of the differential effect of white rot fungi on the degradation of single and mixtures of pesticides using fungi such as Trametes versicolor and Phanerochaete chrysosporium. We also explore the formulation and delivery of fungal bioremedial inoculants to terrestrial ecosystems as well as the use of spent mushroom compost as an approach. Future areas for research and potential exploitation of new techniques are also considered. PMID:23956663

  6. Characteristics of a newly isolated fungus Geotrichum candidum Dec 1 with broad degradation spectrum of xenobiotic compounds.

    PubMed

    Shoda, M

    2003-01-01

    A newly isolated fungus, Geotrichum candidum Dec 1 (abbreviated as Dec 1), was found to have the ability to degrade many xenobiotic compounds such as synthetic dyes, food coloring agents, molasses, organic halogens, lignin and kraft pulp effluents. The broad spectrum of the degradation of these compounds are associated mainly with peroxidases produced by the fungus.

  7. Update on medical and regulatory issues pertaining to compounded and FDA-approved drugs, including hormone therapy

    PubMed Central

    Pinkerton, JoAnn V.; Pickar, James H.

    2016-01-01

    Abstract Objective: We review the historical regulation of drug compounding, concerns about widespread use of non-Food and Drug Admiistration (FDA)-approved compounded bioidentical hormone therapies (CBHTs), which do not have proper labeling and warnings, and anticipated impact of the 2013 Drug Quality and Security Act (DQSA) on compounding. Methods: US government websites were searched for documents concerning drug compounding regulation and oversight from 1938 (passage of Federal Food, Drug, and Cosmetic Act [FDCA]) through 2014, including chronologies, Congressional testimony, FDA guidelines and enforcements, and reports. The FDCA and DQSA were reviewed. PubMed and Google were searched for articles on compounded drugs, including CBHT. Results: Congress explicitly granted the FDA limited oversight of compounded drugs in a 1997 amendment to the FDCA, but the FDA has encountered obstacles in exercising that authority. After 64 patient deaths and 750 adversely affected patients from the 2012 meningitis outbreak due to contaminated compounded steroid injections, Congress passed the DQSA, authorizing the FDA to create a voluntary registration for facilities that manufacture and distribute sterile compounded drugs in bulk and reinforcing FDCA regulations for traditional compounding. Given history and current environment, concerns remain about CBHT product regulation and their lack of safety and efficacy data. Conclusions: The DQSA and its reinforcement of §503A of the FDCA solidifies FDA authority to enforce FDCA provisions against compounders of CBHT. The new law may improve compliance and accreditation by the compounding industry; support state and FDA oversight; and prevent the distribution of misbranded, adulterated, or inconsistently compounded medications, and false and misleading claims, thus reducing public health risk. PMID:26418479

  8. Application of metabolomics to toxicology of drugs of abuse: A mini review of metabolomics approach to acute and chronic toxicity studies.

    PubMed

    Zaitsu, Kei; Hayashi, Yumi; Kusano, Maiko; Tsuchihashi, Hitoshi; Ishii, Akira

    2016-02-01

    Metabolomics has been widely applied to toxicological fields, especially to elucidate the mechanism of action of toxicity. In this review, metabolomics application with focus on the studies of chronic and acute toxicities of drugs of abuse like stimulants, opioids and the recently-distributed designer drugs will be presented in addition to an outline of basic analytical techniques used in metabolomics. Limitation of metabolomics studies and future perspectives will be also provided. Copyright © 2015 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  9. Xenobiotic metal-induced autoimmunity: mercury and silver differentially induce antinucleolar autoantibody production in susceptible H-2s, H-2q and H-2f mice

    PubMed Central

    Hansson, M; Abedi-Valugerdi, M

    2003-01-01

    Xenobiotic-metals such as mercury (Hg) and silver (Ag) induce an H-2 linked antinucleolar autoantibody (ANolA) production in susceptible mice. The mechanism for induction of ANolA synthesis is not well understood. However, it has been suggested that both metals interact with nucleolar proteins and reveal cryptic self-peptides to nontolerant autoreactive T cells, which in turn stimulate specific autoreactive B cells. In this study, we considered this suggestion and asked if mercury and silver display, if not identical, similar cryptic self-peptides, they would induce comparable ANolA responses in H-2 susceptible mice. We analysed the development of ANolA production in mercury- and/or silver-treated mice of H-2s, H-2q and H-2f genotypes. We found that while mercury stimulated ANolA synthesis in all strains tested, silver induced ANolA responses of lower magnitudes in only H-2s and H-2q mice, but not in H-2f mice. Resistance to silver in H-2f mice was independent of the dosage/time-period of silver-treatment and non-H-2 genes. Further studies showed that F1 hybrid crosses between silver-susceptible A.SW (H-2s) and -resistant A.CA (H-2f) mice were resistant to silver, but not mercury with regard to ANolA production. Additionally, the magnitudes of mercury-induced ANolA responses in the F1 hybrids were lower than those of their parental strains. The above differential ANolA responses to mercury and silver can be explained by various factors, including the different display of nucleolar cryptic peptides by these xenobiotics, determinant capture and coexistence of different MHC molecules. Our findings also suggest that the ability of a xenobiotic metal merely to create cryptic self-peptides may not be sufficient for the induction of an ANolA response. PMID:12605692

  10. Collaborative study using common samples to evaluate the performance of anti-drug antibody assays constructed by different companies.

    PubMed

    Niimi, Shingo; Nishimiya, Kazuhiro; Nishidate, Masanobu; Saito, Tetsu; Minoura, Kyoko; Kadotsuji, Kenta; Shimakura, Jin; Shigemizu, Hiroko; Hosogi, Jun; Adachi, Maiko; Hashimoto, Tsutomu; Mori, Tamiki; Harada, Hideki; Yamamoto, Ken-Ichi; Nakamura, Takahiro; Nomura, Tatsuki; Yamaguchi, Itadaki; Sonehara, Kazuhiko; Ishii-Watabe, Akiko; Kawasaki, Nana

    2018-04-01

    This study was undertaken to evaluate the performance of anti-drug antibody (ADA) assays constructed by each participating company using common samples including ADA, drug and human serum. The ADA assays constructed by each company showed good sensitivity and precision for evaluation of ADA. Cut points for screening and confirmatory assays and assay selectivity were determined by various calculation methods. In evaluations of blind ADA samples, nearly similar results were obtained by the study companies in determinations of whether samples were positive or negative except at the lowest sample concentration (5 ng/mL). In measurement of drug tolerance, for almost samples containing ADA and drugs, more positive results were obtained in assays using acid dissociation compared to those without acid dissociation. Overall, the performance of ADA assays constructed by the 10 companies participating in this study was acceptable in terms of sensitivity and reproducibility for detection and evaluation of immunogenicity in both patients and healthy subjects. On the other hand, based on results for samples containing ADA and drugs, validity of results for ADA assays conducted without acid dissociation was less meaningful and more difficult to evaluate. Thus, acid dissociation was confirmed to be useful for improving drug tolerance. Copyright © 2018 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  11. Endogenous and xenobiotic metabolic stability of primary human hepatocytes in long-term 3D spheroid cultures revealed by a combination of targeted and untargeted metabolomics

    PubMed Central

    Vorrink, Sabine U.; Ullah, Shahid; Schmidt, Staffan; Nandania, Jatin; Velagapudi, Vidya; Beck, Olof; Ingelman-Sundberg, Magnus; Lauschke, Volker M.

    2017-01-01

    Adverse reactions or lack of response to medications are important concerns for drug development programs. However, faithful predictions of drug metabolism and toxicity are difficult because animal models show only limited translatability to humans. Furthermore, current in vitro systems, such as hepatic cell lines or primary human hepatocyte (PHH) 2-dimensional (2D) monolayer cultures, can be used only for acute toxicity tests because of their immature phenotypes and inherent instability. Therefore, the migration to novel phenotypically stable models is of prime importance for the pharmaceutical industry. Novel 3-dimensional (3D) culture systems have been shown to accurately mimic in vivo hepatic phenotypes on transcriptomic and proteomic level, but information about their metabolic stability is lacking. Using a combination of targeted and untargeted high-resolution mass spectrometry, we found that PHHs in 3D spheroid cultures remained metabolically stable for multiple weeks, whereas metabolic patterns of PHHs from the same donors cultured as conventional 2D monolayers rapidly deteriorated. Furthermore, pharmacokinetic differences between donors were maintained in 3D spheroid cultures, enabling studies of interindividual variability in drug metabolism and toxicity. We conclude that the 3D spheroid system is metabolically stable and constitutes a suitable model for in vitro studies of long-term drug metabolism and pharmacokinetics.—Vorrink, S. U., Ullah, S., Schmid, S., Nandania, J., Velagapudi, V., Beck, O., Ingelman-Sundberg, M., Lauschke, V. M. Endogenous and xenobiotic metabolic stability of primary human hepatocytes in long-term 3D spheroid cultures revealed by a combination of targeted and untargeted metabolomics. PMID:28264975

  12. Endogenous and xenobiotic metabolic stability of primary human hepatocytes in long-term 3D spheroid cultures revealed by a combination of targeted and untargeted metabolomics.

    PubMed

    Vorrink, Sabine U; Ullah, Shahid; Schmidt, Staffan; Nandania, Jatin; Velagapudi, Vidya; Beck, Olof; Ingelman-Sundberg, Magnus; Lauschke, Volker M

    2017-06-01

    Adverse reactions or lack of response to medications are important concerns for drug development programs. However, faithful predictions of drug metabolism and toxicity are difficult because animal models show only limited translatability to humans. Furthermore, current in vitro systems, such as hepatic cell lines or primary human hepatocyte (PHH) 2-dimensional (2D) monolayer cultures, can be used only for acute toxicity tests because of their immature phenotypes and inherent instability. Therefore, the migration to novel phenotypically stable models is of prime importance for the pharmaceutical industry. Novel 3-dimensional (3D) culture systems have been shown to accurately mimic in vivo hepatic phenotypes on transcriptomic and proteomic level, but information about their metabolic stability is lacking. Using a combination of targeted and untargeted high-resolution mass spectrometry, we found that PHHs in 3D spheroid cultures remained metabolically stable for multiple weeks, whereas metabolic patterns of PHHs from the same donors cultured as conventional 2D monolayers rapidly deteriorated. Furthermore, pharmacokinetic differences between donors were maintained in 3D spheroid cultures, enabling studies of interindividual variability in drug metabolism and toxicity. We conclude that the 3D spheroid system is metabolically stable and constitutes a suitable model for in vitro studies of long-term drug metabolism and pharmacokinetics.-Vorrink, S. U., Ullah, S., Schmid, S., Nandania, J., Velagapudi, V., Beck, O., Ingelman-Sundberg, M., Lauschke, V. M. Endogenous and xenobiotic metabolic stability of primary human hepatocytes in long-term 3D spheroid cultures revealed by a combination of targeted and untargeted metabolomics. © The Author(s).

  13. Natural Dietary Pigments: Potential Mediators against Hepatic Damage Induced by Over-The-Counter Non-Steroidal Anti-Inflammatory and Analgesic Drugs

    PubMed Central

    Jaramillo-Juárez, Fernando

    2018-01-01

    Over-the-counter (OTC) analgesics are among the most widely prescribed and purchased drugs around the world. Most analgesics, including non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen, are metabolized in the liver. The hepatocytes are responsible for drug metabolism and detoxification. Cytochrome P450 enzymes are phase I enzymes expressed mainly in hepatocytes and they account for ≈75% of the metabolism of clinically used drugs and other xenobiotics. These metabolic reactions eliminate potentially toxic compounds but, paradoxically, also result in the generation of toxic or carcinogenic metabolites. Cumulative or overdoses of OTC analgesic drugs can induce acute liver failure (ALF) either directly or indirectly after their biotransformation. ALF is the result of massive death of hepatocytes induced by oxidative stress. There is an increased interest in the use of natural dietary products as nutritional supplements and/or medications to prevent or cure many diseases. The therapeutic activity of natural products may be associated with their antioxidant capacity, although additional mechanisms may also play a role (e.g., anti-inflammatory actions). Dietary antioxidants such as flavonoids, betalains and carotenoids play a preventive role against OTC analgesics-induced ALF. In this review, we will summarize the pathobiology of OTC analgesic-induced ALF and the use of natural pigments in its prevention and therapy. PMID:29364842

  14. Mining the topography and dynamics of the 4D Nucleome to identify novel CNS drug pathways.

    PubMed

    Higgins, Gerald A; Allyn-Feuer, Ari; Georgoff, Patrick; Nikolian, Vahagn; Alam, Hasan B; Athey, Brian D

    2017-07-01

    The pharmacoepigenome can be defined as the active, noncoding province of the genome including canonical spatial and temporal regulatory mechanisms of gene regulation that respond to xenobiotic stimuli. Many psychotropic drugs that have been in clinical use for decades have ill-defined mechanisms of action that are beginning to be resolved as we understand the transcriptional hierarchy and dynamics of the nucleus. In this review, we describe spatial, temporal and biomechanical mechanisms mediated by psychotropic medications. Focus is placed on a bioinformatics pipeline that can be used both for detection of pharmacoepigenomic variants that discretize drug response and adverse events to improve pharmacogenomic testing, and for the discovery of novel CNS therapeutics. This approach integrates the functional topology and dynamics of the transcriptional hierarchy of the pharmacoepigenome, gene variant-driven identification of pharmacogenomic regulatory domains, and mesoscale mapping for the discovery of novel CNS pharmacodynamic pathways in human brain. Examples of the application of this pipeline are provided, including the discovery of valproic acid (VPA) mediated transcriptional reprogramming of neuronal cell fate following injury, and mapping of a CNS pathway glutamatergic pathway for the mood stabilizer lithium. These examples in regulatory pharmacoepigenomics illustrate how ongoing research using the 4D nucleome provides a foundation to further insight into previously unrecognized psychotropic drug pharmacodynamic pathways in the human CNS. Copyright © 2017. Published by Elsevier Inc.

  15. Associations Between Selected Xenobiotics and Antinuclear Antibodies in the National Health and Nutrition Examination Survey, 1999-2004.

    PubMed

    Dinse, Gregg E; Jusko, Todd A; Whitt, Irene Z; Co, Caroll A; Parks, Christine G; Satoh, Minoru; Chan, Edward K L; Rose, Kathryn M; Walker, Nigel J; Birnbaum, Linda S; Zeldin, Darryl C; Weinberg, Clarice R; Miller, Frederick W

    2016-04-01

    Potential associations between background environmental chemical exposures and autoimmunity are understudied. Our exploratory study investigated exposure to individual environmental chemicals and selected mixtures in relation to the presence of antinuclear antibodies (ANA), a widely used biomarker of autoimmunity, in a representative sample of the U.S. This cross-sectional analysis used data on 4,340 participants from the National Health and Nutrition Examination Survey (1999-2004), of whom 14% were ANA positive, to explore associations between ANA and concentrations of dioxins, dibenzofurans, polychlorinated biphenyls, organochlorines, organophosphates, phenols, metals, and other environmental exposures and metabolites measured in participants' serum, whole blood, or urine. For dioxin-like compounds with toxic equivalency factors, we developed and applied a new statistical approach to study selected mixtures. Lognormal models and censored-data methods produced estimates of chemical associations with ANA in males, nulliparous females, and parous females; these estimates were adjusted for confounders and accommodated concentrations below detectable levels. Several associations between chemical concentration and ANA positivity were observed, but only the association in males exposed to triclosan remained statistically significant after correcting for multiple comparisons (mean concentration ratio = 2.8; 95% CI: 1.8, 4.5; p < 0.00001). These data suggest that background levels of most xenobiotic exposures typical in the U.S. population are not strongly associated with ANA. Future studies should ideally reduce exposure misclassification by including prospective measurement of the chemicals of concern and should track changes in ANA and other autoantibodies over time. Dinse GE, Jusko TA, Whitt IZ, Co CA, Parks CG, Satoh M, Chan EKL, Rose KM, Walker NJ, Birnbaum LS, Zeldin DC, Weinberg CR, Miller FW. 2016. Associations between selected xenobiotics and antinuclear

  16. An overview of drug delivery vehicles for cancer treatment: Nanocarriers and nanoparticles including photovoltaic nanoparticles.

    PubMed

    Chowdhury, Silvia; Yusof, Faridah; Salim, Wan Wardatul Amani Wan; Sulaiman, Nadzril; Faruck, Mohammad Omer

    2016-11-01

    Cancer is a complicated disease for which finding a cure presents challenges. In recent decades, new ways to treat cancer are being sought; one being nanomedicine, which manipulates nanoparticles to target a cancer and release drugs directly to the cancer cells. A number of cancer treatments based on nanomedicine are under way and mostly are in preclinical trials owing to challenges in administration, safety, and effectiveness. One alternative method for drug delivery is the use of photovoltaic nanoparticles, which has the potential to deliver drugs via light activation. The concepts are based on standard photovoltaic cell that holds opposite charges on its surfaces and releases drugs when charge intensity or polarity changes upon photo-stimulation such as from a laser source or sunlight. This review will cover some recent progress in cancer treatment using nanoparticles, including photovoltaic nanoparticles. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Passive rGE or developmental gene-environment cascade? An investigation of the role of xenobiotic metabolism genes in the association between smoke exposure during pregnancy and child birth weight

    PubMed Central

    Marceau, Kristine; Palmer, Rohan H.C.; Neiderhiser, Jenae M.; Smith, Taylor F.; McGeary, John E.; Knopik, Valerie S.

    2016-01-01

    There is considerable evidence that smoke exposure during pregnancy (SDP) environmentally influences birth weight after controlling for genetic influences and maternal characteristics. However, maternal smoking during pregnancy – the behavior that leads to smoke exposure during pregnancy – is also genetically-influenced, indicating the potential role of passive gene-environment correlation. An alternative to passive gene-SDP correlation is a cascading effect whereby maternal and child genetic influences are causally linked to prenatal exposures, which then have an ‘environmental’ effect on the development of the child’s biology and behavior. We describe and demonstrate a conceptual framework for disentangling passive rGE from this cascading GE effect using a systems-based polygenic scoring approach comprised of genes shown to be important in the xenobiotic (substances foreign to the body) metabolism pathway. Data were drawn from 5,044 families from the Avon Longitudinal Study of Parents and Children with information on maternal SDP, birth weight, and genetic polymorphisms in the xenobiotic pathway. Within a k-fold cross-validation approach (k=5), we created weighted maternal and child polygenic scores using 18 polymorphisms from 10 genes that have been implicated in the xenobiotic metabolism pathway. Mothers and children shared variation in xenobiotic metabolism genes. Amongst mothers who smoked during pregnancy, neither maternal nor child xenobiotic metabolism polygenic scores were associated with a higher likelihood of smoke exposure during pregnancy, or the severity of smoke exposure during pregnancy (and therefore, neither proposed mechanism was supported), or with child birth weight. SDP was consistently associated with lower child birth weight controlling for the polygenic scores, maternal educational attainment, social class, psychiatric problems, and age. Limitations of the study design and the potential of the framework using other designs are

  18. Xenobiotic Metabolizing Enzyme and Transporter Gene Expression in Primary Cultures of Human Hepatocytes Modulated by ToxCast Chemicals

    EPA Science Inventory

    ToxCast chemicals were assessed for induction or suppression of xenobiotic metabolizing enzyme and transporter gene expression using primary human hepatocytes. The mRNA levels of 14 target and 2 control genes were measured: ABCB1, ABCB11, ABCG2, SLCO1B1, CYP1A1, CYP1A2, CYP2B6, C...

  19. [Human drug metabolizing enzymes. II. Conjugation enzymes].

    PubMed

    Vereczkey, L; Jemnitz, K; Gregus, Z

    1998-09-01

    In this review we focus on human conjugation enzymes (UDP-glucuronyltransferases, methyl-trasferases, N-acetyl-transferases, O-acetyl-transferases, Amidases/carboxyesterases, sulfotransferases, Glutation-S-transferases and the enzymes involved in the conjugation with amino acids) that participate in the metabolism of xenobiotics. Although conjugation reactions in most of the cases result in detoxication, more and more publications prove that the reactions catalysed by these enzymes very often lead to activated molecules that may attack macromolecules (proteins, RNAs, DNAs), resulting in toxicity (liver, neuro-, embryotoxicity, allergy, carcinogenecity). We have summarised the data available on these enzymes concerning their catalytic profile and specificity, inhibition, induction properties, their possible role in the generation of toxic compounds, their importance in clinical practice and drug development.

  20. Monocrotophos Induces the Expression and Activity of Xenobiotic Metabolizing Enzymes in Pre-Sensitized Cultured Human Brain Cells

    PubMed Central

    Tripathi, Vinay K.; Kumar, Vivek; Singh, Abhishek K.; Kashyap, Mahendra P.; Jahan, Sadaf; Pandey, Ankita; Alam, Sarfaraz; Khan, Feroz; Khanna, Vinay K.; Yadav, Sanjay; Lohani, Mohtshim; Pant, Aditya B.

    2014-01-01

    The expression and metabolic profile of cytochrome P450s (CYPs) is largely missing in human brain due to non-availability of brain tissue. We attempted to address the issue by using human brain neuronal (SH-SY5Y) and glial (U373-MG) cells. The expression and activity of CYP1A1, 2B6 and 2E1 were carried out in the cells exposed to CYP inducers viz., 3-methylcholanthrene (3-MC), cyclophosphamide (CPA), ethanol and known neurotoxicant- monocrotophos (MCP), a widely used organophosphorous pesticide. Both the cells show significant induction in the expression and CYP-specific activity against classical inducers and MCP. The induction level of CYPs was comparatively lower in MCP exposed cells than cells exposed to classical inducers. Pre-exposure (12 h) of cells to classical inducers significantly added the MCP induced CYPs expression and activity. The findings were concurrent with protein ligand docking studies, which show a significant modulatory capacity of MCP by strong interaction with CYP regulators-CAR, PXR and AHR. Similarly, the known CYP inducers- 3-MC, CPA and ethanol have also shown significantly high docking scores with all the three studied CYP regulators. The expression of CYPs in neuronal and glial cells has suggested their possible association with the endogenous physiology of the brain. The findings also suggest the xenobiotic metabolizing capabilities of these cells against MCP, if received a pre-sensitization to trigger the xenobiotic metabolizing machinery. MCP induced CYP-specific activity in neuronal cells could help in explaining its effect on neurotransmission, as these CYPs are known to involve in the synthesis/transport of the neurotransmitters. The induction of CYPs in glial cells is also of significance as these cells are thought to be involved in protecting the neurons from environmental insults and safeguard them from toxicity. The data provide better understanding of the metabolizing capability of the human brain cells against xenobiotics

  1. Maintenance of drug metabolism and transport functions in human precision-cut liver slices during prolonged incubation for 5 days.

    PubMed

    Starokozhko, Viktoriia; Vatakuti, Suresh; Schievink, Bauke; Merema, Marjolijn T; Asplund, Annika; Synnergren, Jane; Aspegren, Anders; Groothuis, Geny M M

    2017-05-01

    Human precision-cut liver slices (hPCLS) are a valuable ex vivo model that can be used in acute toxicity studies. However, a rapid decline in metabolic enzyme activity limits their use in studies that require a prolonged xenobiotic exposure. The aim of the study was to extend the viability and function of hPCLS to 5 days of incubation. hPCLS were incubated in two media developed for long-term culture of hepatocytes, RegeneMed ® , and Cellartis ® , and in the standard medium WME. Maintenance of phase I and II metabolism was studied both on gene expression as well as functional level using a mixture of CYP isoform-specific substrates. Albumin synthesis, morphological integrity, and glycogen storage was assessed, and gene expression was studied by transcriptomic analysis using microarrays with a focus on genes involved in drug metabolism, transport and toxicity. The data show that hPCLS retain their viability and functionality during 5 days of incubation in Cellartis ® medium. Albumin synthesis as well as the activity and gene expression of phase I and II metabolic enzymes did not decline during 120-h incubation in Cellartis ® medium, with CYP2C9 activity as the only exception. Glycogen storage and morphological integrity were maintained. Moreover, gene expression changes in hPCLS during incubation were limited and mostly related to cytoskeleton remodeling, fibrosis, and moderate oxidative stress. The expression of genes involved in drug transport, which is an important factor in determining the intracellular xenobiotic exposure, was also unchanged. Therefore, we conclude that hPCLS cultured in Cellartis ® medium are a valuable human ex vivo model for toxicological and pharmacological studies that require prolonged xenobiotic exposure.

  2. Stress- and glucocorticoid-induced priming of neuroinflammatory responses: potential mechanisms of stress-induced vulnerability to drugs of abuse.

    PubMed

    Frank, Matthew G; Watkins, Linda R; Maier, Steven F

    2011-06-01

    Stress and stress-induced glucocorticoids (GCs) sensitize drug abuse behavior as well as the neuroinflammatory response to a subsequent pro-inflammatory challenge. Stress also predisposes or sensitizes individuals to develop substance abuse. There is an emerging evidence that glia and glia-derived neuroinflammatory mediators play key roles in the development of drug abuse. Drugs of abuse such as opioids, psychostimulants, and alcohol induce neuroinflammatory mediators such as pro-inflammatory cytokines (e.g. interleukin (IL)-1β), which modulate drug reward, dependence, and tolerance as well as analgesic properties. Drugs of abuse may directly activate microglial and astroglial cells via ligation of Toll-like receptors (TLRs), which mediate the innate immune response to pathogens as well as xenobiotic agents (e.g. drugs of abuse). The present review focuses on understanding the immunologic mechanism(s) whereby stress primes or sensitizes the neuroinflammatory response to drugs of abuse and explores whether stress- and GC-induced sensitization of neuroimmune processes predisposes individuals to drug abuse liability and the role of neuroinflammatory mediators in the development of drug addiction. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. Risk assessment for selected xenobiotics by bioassay methods with higher plants

    NASA Astrophysics Data System (ADS)

    Günther, Petra; Pestemer, Wilfried

    1990-05-01

    Different bioassays with higher plants were approved for use in a bioassay procedure for testing of xenobiotics according to the German Chemicals Act. Selected environmental pollutants (atrazine, cadmium chloride, 2,6-dichlorobenzonitrile, pentachlorophenol, potassium dichromate, thiourea), all from a list of reference chemicals, were tested with these methods. Dose-response curves for growth of oats and turnips were evaluated in soil and vermiculite (nonsorptive substrate), and availability to plants was calculated by comparing the EC50 values for one chemical in both substrates. The most active chemical was atrazine, followed by 2,6-dichlorobenzonitrile, pentachlorophenol, potassium dichromate, cadmium chloride, and thiourea. The least available compound to plants was pentachlorophenol, tested with turnips ( Brassica rapa var. rapa). The strongest inhibition of germination, demonstrated in an in vitro assay with garden cress ( Lepidium sativum), was found with 2,6-dichlorobenzonitrile, the lowest with atrazine. The effect of an extended exposure of the plants to the chemicals was evaluated in a long-term bioassay with oats ( Avena sativa) in hydroponic culture. Several dose-response curves during the growing period were derived. It was found that the EC50 values for atrazine and thiourea decreased markedly during the first four weeks; thereafter the changes were much smaller. As an overall conclusion, a bioassay procedure is proposed that can be included in the graduated plan recommended by the German Chemicals Act.

  4. Xenobiotic metabolism in human skin and 3D human skin reconstructs: a review.

    PubMed

    Gibbs, Sue; van de Sandt, Johannes J M; Merk, Hans F; Lockley, David J; Pendlington, Ruth U; Pease, Camilla K

    2007-12-01

    In this review, we discuss and compare studies of xenobiotic metabolism in both human skin and 3D human skin reconstructs. In comparison to the liver, the skin is a less studied organ in terms of characterising metabolic capability. While the skin forms the major protective barrier to environmental chemical exposure, it is also a potential target organ for adverse health effects. Occupational, accidental or intended-use exposure to toxic chemicals could result in acute or delayed injury to the skin (e.g. inflammation, allergy, cancer). Skin metabolism may play a role in the manifestation or amelioration of adverse effects via the topical route. Today, we have robust testing strategies to assess the potential for local skin toxicity of chemical exposure. Such methods (e.g. the local lymph node assay for assessing skin sensitisation; skin painting carcinogenicity studies) incorporate skin metabolism implicitly in the in vivo model system used. In light of recent European legislation (i.e. 7(th) Amendment to the Cosmetics Directive and Registration Evaluation and Authorisation of existing Chemicals (REACH)), non-animal approaches will be required to reduce and replace animal experiments for chemical risk assessment. It is expected that new models and approaches will need to account for skin metabolism explicitly, as the mechanisms of adverse effects in the skin are deconvoluted. 3D skin models have been proposed as a tool to use in new in vitro alternative approaches. In order to be able to use 3D skin models in this context, we need to understand their metabolic competency in relation to xenobiotic biotransformation and whether functional activity is representative of that seen in human skin.

  5. Microbial P450 Enzymes in Bioremediation and Drug Discovery: Emerging Potentials and Challenges.

    PubMed

    Bhattacharya, Sukanta S; Yadav, Jagjit S

    2018-01-01

    Cytochrome P450 enzymes are a structurally conserved but functionally diverse group of heme-containing mixed function oxidases found across both prokaryotic and eukaryotic forms of the microbial world. Microbial P450s are known to perform diverse functions ranging from the synthesis of cell wall components to xenobiotic/drug metabolism to biodegradation of environmental chemicals. Conventionally, many microbial systems have been reported to mimic mammalian P450-like activation of drugs and were proposed as the in-vitro models of mammalian drug metabolism. Recent reports suggest that native or engineered forms of specific microbial P450s from these and other microbial systems could be employed for desired specific biotransformation reactions toward natural and synthetic (drug) compounds underscoring their emerging potential in drug improvement and discovery. On the other hand, microorganisms particularly fungi and actinomycetes have been shown to possess catabolic P450s with unusual potential to degrade toxic environmental chemicals including persistent organic pollutants (POPs). Wood-rotting basidiomycete fungi in particular have revealed the presence of exceptionally large P450 repertoire (P450ome) in their genomes, majority of which are however orphan (with no known function). Our pre- and post-genomic studies have led to functional characterization of several fungal P450s inducible in response to exposure to several environmental toxicants and demonstration of their potential in bioremediation of these chemicals. This review is an attempt to summarize the postgenomic unveiling of this versatile enzyme superfamily in microbial systems and investigation of their potential to synthesize new drugs and degrade persistent pollutants, among other biotechnological applications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  6. Interaction of Isoflavones with the BCRP/ABCG2 Drug Transporter

    PubMed Central

    Bircsak, Kristin M; Aleksunes, Lauren M

    2015-01-01

    This review will provide a comprehensive overview of the interactions between dietary isoflavones and the ATP-binding cassette (ABC) G2 efflux transporter, which is also named the breast cancer resistance protein (BCRP). Expressed in a variety of organs including the liver, kidneys, intestine, and placenta, BCRP mediates the disposition and excretion of numerous endogenous chemicals and xenobiotics. Isoflavones are a class of naturally-occurring compounds that are found at high concentrations in commonly consumed foods and dietary supplements. A number of isoflavones, including genistein and daidzein and their metabolites, interact with BCRP as substrates, inhibitors, and/or modulators of gene expression. To date, a variety of model systems have been employed to study the ability of isoflavones to serve as substrates and inhibitors of BCRP; these include whole cells, inverted plasma membrane vesicles, in situ organ perfusion, as well as in vivo rodent and sheep models. Evidence suggests that BCRP plays a role in mediating the disposition of isoflavones and in particular, their conjugated forms. Furthermore, as inhibitors, these compounds may aid in reversing multidrug resistance and sensitizing cancer cells to chemotherapeutic drugs. This review will also highlight the consequences of altered BCRP expression and/or function on the pharmacokinetics and toxicity of chemicals following isoflavone exposure. PMID:26179608

  7. Modulation of Xenobiotic Metabolizing Enzyme and Transporter Gene Expression in Primary Cultures of Human Hepatocytes by ToxCast Chemicals

    EPA Science Inventory

    ToxCast chemicals were assessed for induction or suppression of xenobiotic metabolizing enzyme and transporter gene expression using primary human hepatocytes. The mRNA levels of 14 target and 2 control genes were measured: ABCB1, ABCB11, ABCG2, SLCO1B1, CYP1A1, CYP1A2, CYP2B6, C...

  8. Low levels of graphene and graphene oxide inhibit cellular xenobiotic defense system mediated by efflux transporters.

    PubMed

    Liu, Su; Jiang, Wei; Wu, Bing; Yu, Jing; Yu, Haiyan; Zhang, Xu-Xiang; Torres-Duarte, Cristina; Cherr, Gary N

    2016-01-01

    Low levels of graphene and graphene oxide (GO) are considered to be environmentally safe. In this study, we analyzed the potential effects of graphene and GO at relatively low concentrations on cellular xenobiotic defense system mediated by efflux transporters. The results showed that graphene (<0.5 μg/mL) and GO (<20 μg/mL) did not decrease cell viability, generate reactive oxygen species, or disrupt mitochondrial function. However, graphene and GO at the nontoxic concentrations could increase calcein-AM (CAM, an indicator of membrane ATP-binding cassette (ABC) transporter) activity) accumulation, indicating inhibition of ABC transporters' efflux capabilities. This inhibition was observed even at 0.005 μg/mL graphene and 0.05 μg/mL GO, which are 100 times and 400 times lower than their lowest toxic concentration from cytotoxicity experiments, respectively. The inhibition of ABC transporters significantly increased the toxicity of paraquat and arsenic, known substrates of ABC transporters. The inhibition of ABC transporters was found to be based on graphene and GO damaging the plasma membrane structure and fluidity, thus altering functions of transmembrane ABC transporters. This study demonstrates that low levels of graphene and GO are not environmentally safe since they can significantly make cell more susceptible to other xenobiotics, and this chemosensitizing activity should be considered in the risk assessment of graphene and GO.

  9. Drug transporters, the blood–testis barrier, and spermatogenesis

    PubMed Central

    Su, Linlin; Mruk, Dolores D; Cheng, C Yan

    2015-01-01

    The blood–testis barrier (BTB), which is created by adjacent Sertoli cells near the basement membrane, serves as a ‘gatekeeper’ to prohibit harmful substances from reaching developing germ cells, most notably postmeiotic spermatids. The BTB also divides the seminiferous epithelium into the basal and adluminal (apical) compartment so that postmeiotic spermatid development, namely spermiogenesis, can take place in a specialized microenvironment in the apical compartment behind the BTB. The BTB also contributes, at least in part, to the immune privilege status of the testis, so that anti-sperm antibodies are not developed against antigens that are expressed transiently during spermatogenesis. Recent studies have shown that numerous drug transporters are expressed by Sertoli cells. However, many of these same drug transporters are also expressed by spermatogonia, spermatocytes, round spermatids, elongating spermatids, and elongated spermatids, suggesting that the developing germ cells are also able to selectively pump drugs ‘in’ and/or ‘out’ via influx or efflux pumps. We review herein the latest developments regarding the role of drug transporters in spermatogenesis. We also propose a model utilized by the testis to protect germ cell development from ‘harmful’ environmental toxicants and xenobiotics and/or from ‘therapeutic’ substances (e.g. anticancer drugs). We also discuss how drug transporters that are supposed to protect spermatogenesis can work against the testis in some instances. For example, when drugs (e.g. male contraceptives) that can perturb germ cell adhesion and/or maturation are actively pumped out of the testis or are prevented from entering the apical compartment, such as by efflux pumps. PMID:21134990

  10. Environmental Xenobiotics and the Antihormones Cyproterone Acetate and Spironolactone Use the Nuclear Hormone Pregnenolone X Receptor to Activate the CYP3A23 Hormone Response Element

    PubMed Central

    SCHUETZ, ERIN G.; BRIMER, CYNTHIA; SCHUETZ, JOHN D.

    2013-01-01

    The pregnenolone X receptor (PXR), a new member of the nuclear hormone receptor superfamily, was recently demonstrated to mediate glucocorticoid agonist and antagonist activation of a hormone response element spaced by three nucleotides (DR-3) within the rat CYP3A23 promoter. Because many other steroids and xenobiotics can up-regulate CYP3A23 expression, we determined whether some of these other regulators used PXR to activate the CYP3A23 DR-3. Transient cotransfection of LLC-PK1 cells with (CYP3A23)2-tk-CAT and mouse PXR demonstrated that the organochlorine pesticides transnonachlor and chlordane and the nonplanar polychlorinated biphenyls (PCBs) each induced the CYP3A23 DR-3 element, and this activation required PXR. Additionally, this study found that PXR is activated to induce (CYP3A23)2-tk-CAT by antihormones of several steroid classes including the antimineralocorticoid spironolactone and the antiandrogen cyproterone acetate. These studies reveal that PXR is involved in the induction of CYP3A23 by pharmacologically and structurally distinct steroids and xenobiotics. Moreover, PXR-mediated PCB activation of the (CYP3A23)2-tk-CAT may serve as a rapid assay for effects of nonplanar PCBs. PMID:9855641

  11. Pharmacokinetic Herb-Drug Interactions: Insight into Mechanisms and Consequences.

    PubMed

    Oga, Enoche F; Sekine, Shuichi; Shitara, Yoshihisa; Horie, Toshiharu

    2016-04-01

    Herbal medicines are currently in high demand, and their popularity is steadily increasing. Because of their perceived effectiveness, fewer side effects and relatively low cost, they are being used for the management of numerous medical conditions. However, they are capable of affecting the pharmacokinetics and pharmacodynamics of coadministered conventional drugs. These interactions are particularly of clinically relevance when metabolizing enzymes and xenobiotic transporters, which are responsible for the fate of many drugs, are induced or inhibited, sometimes resulting in unexpected outcomes. This article discusses the general use of herbal medicines in the management of several ailments, their concurrent use with conventional therapy, mechanisms underlying herb-drug interactions (HDIs) as well as the drawbacks of herbal remedy use. The authors also suggest means of surveillance and safety monitoring of herbal medicines. Contrary to popular belief that "herbal medicines are totally safe," we are of the view that they are capable of causing significant toxic effects and altered pharmaceutical outcomes when coadministered with conventional medicines. Due to the paucity of information as well as sometimes conflicting reports on HDIs, much more research in this field is needed. The authors further suggest the need to standardize and better regulate herbal medicines in order to ensure their safety and efficacy when used alone or in combination with conventional drugs.

  12. Various pharmacogenetic aspects of antiepileptic drug therapy: a review.

    PubMed

    Mann, Michael W; Pons, Gerard

    2007-01-01

    Pharmacogenetics concerns the influence of an individual's genetic background on the pharmacokinetics and pharmacodynamics of xenobiotics. Much of the pharmacogenetic data in the field of epilepsy deals with the pharmacokinetics of antiepileptic drugs (AEDs). In particular, two polymorphisms of cytochrome P450 2C9 are known to slow down the metabolism of phenytoin to a degree that increases the risk of the neurotoxic adverse effects of this drug among carriers of these polymorphisms. A significant number of patients with epilepsy do not respond to AEDs and such pharmacoresistance is a major, largely unsolved, problem that is likely to be multifactorial in nature. In this regard, genetic factors may influence transmembrane drug transporter proteins, thereby modifying the intracerebral penetration of AEDs. Monogenic idiopathic epilepsies are rare and frequently associated with ion channel mutations; however, to date, a consistent relationship between changes in channel properties and clinical phenotype has not been established nor has any association between genotype and response to specific treatment options. Polymorphisms of drug targets may represent another genetic facet in epilepsy: a recent study demonstrated for the first time a polymorphism of a drug target (the alpha-subunit of a voltage-gated sodium channel) associated in clinical practice with differing response to two classic AEDs. Adverse drug reactions and teratogenicity of AEDs remain a major concern. Whole-genome single nucleotide polymorphism profiling might in the future help to determine genetic predisposing factors for adverse drug reactions. Recently, in Han Chinese treated with carbamazepine and presenting with Stevens-Johnson syndrome, a strong association was found with HLA B*1502. If genetically targeted drug development becomes more affordable/cost efficient in the near future, the development of new drugs for relatively rare diseases could become economically viable for the pharmaceutical

  13. Applicability of the Rayleigh equation for enantioselective metabolism of chiral xenobiotics by microsomes, hepatocytes and in-vivo retention in rabbit tissues

    PubMed Central

    Jammer, Shifra; Gelman, Faina; Lev, Ovadia

    2016-01-01

    In this study we propose a new approach for analyzing the enantioselective biodegradation of some antidepressant drugs mediated by human and rat liver microsomes by using the Rayleigh equation to describe the enantiomeric enrichment−conversion dependencies. Analysis of reported degradation data of additional six pesticides, an alpha blocker and a flame retardant by microsomes or hepatocytes in vitro reaffirmed the universality of the approach. In all the in vitro studied cases that involved enantioselective degradation, a Rayleigh dependence of the enantiomeric enrichment was observed. Published data regarding in vivo retention of myclobutanil in liver, kidney, muscle and brain tissues of rabbits following injection of the racemate were remodeled showing prevalence of the Rayleigh law for the chiral enrichment of the fungicide in the various tissues. This approach will revolutionize data organization in metabolic pathway research of target xenobiotics by either liver microsomes, hepatocytes or their organ-specific in vivo retention. The fact that the enantiomeric enrichment as a function of the conversion can be described by a single quantifier, will pave the road for the use of structure activity predictors of the enantiomeric enrichment and for mechanistic discrimination based on parametric dependence of the quantifier. PMID:27021918

  14. Glucose Transporters at the Blood-Brain Barrier: Function, Regulation and Gateways for Drug Delivery.

    PubMed

    Patching, Simon G

    2017-03-01

    Glucose transporters (GLUTs) at the blood-brain barrier maintain the continuous high glucose and energy demands of the brain. They also act as therapeutic targets and provide routes of entry for drug delivery to the brain and central nervous system for treatment of neurological and neurovascular conditions and brain tumours. This article first describes the distribution, function and regulation of glucose transporters at the blood-brain barrier, the major ones being the sodium-independent facilitative transporters GLUT1 and GLUT3. Other GLUTs and sodium-dependent transporters (SGLTs) have also been identified at lower levels and under various physiological conditions. It then considers the effects on glucose transporter expression and distribution of hypoglycemia and hyperglycemia associated with diabetes and oxygen/glucose deprivation associated with cerebral ischemia. A reduction in glucose transporters at the blood-brain barrier that occurs before the onset of the main pathophysiological changes and symptoms of Alzheimer's disease is a potential causative effect in the vascular hypothesis of the disease. Mutations in glucose transporters, notably those identified in GLUT1 deficiency syndrome, and some recreational drug compounds also alter the expression and/or activity of glucose transporters at the blood-brain barrier. Approaches for drug delivery across the blood-brain barrier include the pro-drug strategy whereby drug molecules are conjugated to glucose transporter substrates or encapsulated in nano-enabled delivery systems (e.g. liposomes, micelles, nanoparticles) that are functionalised to target glucose transporters. Finally, the continuous development of blood-brain barrier in vitro models is important for studying glucose transporter function, effects of disease conditions and interactions with drugs and xenobiotics.

  15. External validation of structure-biodegradation relationship (SBR) models for predicting the biodegradability of xenobiotics.

    PubMed

    Devillers, J; Pandard, P; Richard, B

    2013-01-01

    Biodegradation is an important mechanism for eliminating xenobiotics by biotransforming them into simple organic and inorganic products. Faced with the ever growing number of chemicals available on the market, structure-biodegradation relationship (SBR) and quantitative structure-biodegradation relationship (QSBR) models are increasingly used as surrogates of the biodegradation tests. Such models have great potential for a quick and cheap estimation of the biodegradation potential of chemicals. The Estimation Programs Interface (EPI) Suite™ includes different models for predicting the potential aerobic biodegradability of organic substances. They are based on different endpoints, methodologies and/or statistical approaches. Among them, Biowin 5 and 6 appeared the most robust, being derived from the largest biodegradation database with results obtained only from the Ministry of International Trade and Industry (MITI) test. The aim of this study was to assess the predictive performances of these two models from a set of 356 chemicals extracted from notification dossiers including compatible biodegradation data. Another set of molecules with no more than four carbon atoms and substituted by various heteroatoms and/or functional groups was also embodied in the validation exercise. Comparisons were made with the predictions obtained with START (Structural Alerts for Reactivity in Toxtree). Biowin 5 and Biowin 6 gave satisfactorily prediction results except for the prediction of readily degradable chemicals. A consensus model built with Biowin 1 allowed the diminution of this tendency.

  16. Antibodies, synthetic peptides and related constructs for planetary health based on green chemistry in the Anthropocene.

    PubMed

    Caoili, Salvador Eugenio

    2018-03-01

    The contemporary Anthropocene is characterized by rapidly evolving complex global challenges to planetary health vis-a-vis sustainable development, yet innovation is constrained under the prevailing precautionary regime that regulates technological change. Small-molecule xenobiotic drugs are amenable to efficient large-scale industrial synthesis; but their pharmacokinetics, pharmacodynamics, interactions and ultimate ecological impact are difficult to predict, raising concerns over initial testing and environmental contamination. Antibodies and similar agents can serve as antidotes and drug buffers or vehicles to address patient safety and decrease dosing requirements. More generally, peptidic agents including synthetic peptide-based constructs exemplified by vaccines can be used together with or instead of nonpeptidic xenobiotics, thus enabling advances in planetary health based on principles of green chemistry from manufacturing through final disposition.

  17. Inhalation exposure of rats to asphalt fumes generated at paving temperatures alters pulmonary xenobiotic metabolism pathways without lung injury.

    PubMed Central

    Ma, Jane Y C; Rengasamy, Apavoo; Frazer, Dave; Barger, Mark W; Hubbs, Ann F; Battelli, Lori; Tomblyn, Seith; Stone, Samuel; Castranova, Vince

    2003-01-01

    Asphalt fumes are complex mixtures of various organic compounds, including polycyclic aromatic hydrocarbons (PAHs). PAHs require bioactivation by the cytochrome P-450 monooxygenase system to exert toxic/carcinogenic effects. The present study was carried out to characterize the acute pulmonary inflammatory responses and the alterations of pulmonary xenobiotic pathways in rats exposed to asphalt fumes by inhalation. Rats were exposed at various doses and time periods to air or to asphalt fumes generated at paving temperatures. To assess the acute damage and inflammatory responses, differential cell counts, acellular lactate dehydrogenase (LDH) activity, and protein content of bronchoalveolar lavage fluid were determined. Alveolar macrophage (AM) function was assessed by monitoring generation of chemiluminescence and production of tumor necrosis factor-alpha and interleukin-1. Alteration of pulmonary xenobiotic pathways was determined by monitoring the protein levels and activities of P-450 isozymes (CYP1A1 and CYP2B1), glutathioneS-transferase (GST), and NADPH:quinone oxidoreductase (QR). The results show that acute asphalt fume exposure did not cause neutrophil infiltration, alter LDH activity or protein content, or affect AM function, suggesting that short-term asphalt fume exposure did not induce acute lung damage or inflammation. However, acute asphalt fume exposure significantly increased the activity and protein level of CYP1A1 whereas it markedly reduced the activity and protein level of CYP2B1 in the lung. The induction of CYP1A1 was localized in nonciliated bronchiolar epithelial (Clara) cells, alveolar septa, and endothelial cells by immunofluorescence microscopy. Cytosolic QR activity was significantly elevated after asphalt fume exposure, whereas GST activity was not affected by the exposure. This induction of CYP1A1 and QR with the concomitant down-regulation of CYP2B1 after asphalt fume exposure could alter PAH metabolism and may lead to potential

  18. 41 CFR 105-74.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What must I include in my drug-free workplace statement? 105-74.205 Section 105-74.205 Public Contracts and Property Management Federal Property Management Regulations System (Continued) GENERAL SERVICES ADMINISTRATION...

  19. Evidence for triclosan-induced activation of human and rodent xenobiotic nuclear receptors.

    PubMed

    Paul, Katie B; Thompson, Jerry T; Simmons, Steven O; Vanden Heuvel, John P; Crofton, Kevin M

    2013-10-01

    The bacteriostat triclosan (2,4,4'-trichloro-2'-hydroxydiphenylether) (TCS) decreases rat serum thyroxine via putative nuclear receptor (NR) interaction(s) and subsequent transcriptional up-regulation of hepatic catabolism and clearance. However, due to the evolutionary divergence of the constitutive androstane and pregnane-X receptors (CAR, PXR), TCS-mediated downstream effects may be species-dependent. To test the hypothesis that TCS activates xenobiotic NRs across species, cell-based NR reporter assays were employed to assess potential activation of rat, mouse, and human PXR, and rat, mouse, and three splice variants of human CAR. TCS activated hPXR, acted as an inverse agonist of hCAR1, and as a weak agonist of hCAR3. TCS failed to activate rPXR in full-length receptor reporter assays, and instead acted as a modest inverse agonist of rCAR. Consistent with the rat data, TCS also failed to activate mPXR and was a modest inverse agonist of mCAR. These data suggest that TCS may interact with multiple NRs, including hPXR, hCAR1, hCAR3, and rCAR in order to potentially affect hepatic catabolism. Overall these data support the conclusion that TCS may interact with NRs to regulate hepatic catabolism and downstream thyroid hormone homeostasis in both rat and human models, though perhaps by divergent mechanisms. Published by Elsevier Ltd.

  20. Active and passive transport of drugs in the human placenta.

    PubMed

    Włoch, Stanisław; Pałasz, Artur; Kamiński, Marcin

    2009-10-01

    The human placenta, characterized by the processes of passive transport and facilitated diffusion, contains numerous active transport proteins, usually located in the microvilli of the syncytiotrophoblast or in the endothelium of the capillaries of the villi. These proteins use either the energy from ATP hydrolysis or other mechanisms resulting, among others, from the formation of the maternofetal ion gradient, which facilitates the transfer of various endogenous substances or xenobiotics across the body membranes. The proteins either trigger the efflux of these substances from the fetal tissues via the placenta into the maternal bloodstream, or conversely they accumulate them in the fetal tissues. Both the placenta and the fetus are equipped with independent systems of enzymes of 1st and 2nd phase of substrate metabolism, such as CYP450, glucuronyltransferase or sulphatase. An active therapy with a wide range of drugs, often at high toxicity levels, either shortly before or during pregnancy, has naturally posed a question concerning the degree of impermeability of the placental barrier and how effectively it can be crossed, including any possible negative embryotoxic or teratogenic consequences. Such hazards seem to be quite real, as many drugs are substrates for ABC transporters. Also the placenta itself, including its structure, is subject to vast transformations during pregnancy which may be observed as the thinning of the barrier separating the maternal blood from the fetal one, from 20-30 microm in the first trimester of gestation down to 2-4 microm in the third trimester of gestation.

  1. Reappraisal of xenobiotic-induced, oxidative stress-mediated cellular injury in chronic pancreatitis: A systematic review

    PubMed Central

    Siriwardena, Ajith K

    2014-01-01

    AIM: To reappraise the hypothesis of xenobiotic induced, cytochrome P450-mediated, micronutrient-deficient oxidative injury in chronic pancreatitis. METHODS: Individual searches of the Medline and Embase databases were conducted for each component of the theory of oxidative-stress mediated cellular injury for the period from 1st January 1990 to 31st December 2012 using appropriate medical subject headings. Boolean operators were used. The individual components were drawn from a recent update on theory of oxidative stress-mediated cellular injury in chronic pancreatitis. RESULTS: In relation to the association between exposure to volatile hydrocarbons and chronic pancreatitis the studies fail to adequately control for alcohol intake. Cytochrome P450 (CYP) induction occurs as a diffuse hepatic and extra-hepatic response to xenobiotic exposure rather than an acinar cell-specific process. GSH depletion is not consistently confirmed. There is good evidence of superoxide dismutase depletion in acute phases of injury but less to support a chronic intra-acinar depletion. Although the liver is the principal site of CYP induction there is no evidence to suggest that oxidative by-products are carried in bile and reflux into the pancreatic duct to cause injury. CONCLUSION: Pancreatic acinar cell injury due to short-lived oxygen free radicals (generated by injury mediated by prematurely activated intra-acinar trypsin) is an important mechanism of cell damage in chronic pancreatitis. However, in contemporary paradigms of chronic pancreatitis this should be seen as one of a series of cell-injury mechanisms rather than a sole mediator. PMID:24659895

  2. Application of simple mathematical expressions to relate the half-lives of xenobiotics in rats to values in humans.

    PubMed

    Ward, Keith W; Erhardt, Paul; Bachmann, Kenneth

    2005-01-01

    Previous publications from GlaxoSmithKline and University of Toledo laboratories convey our independent attempts to predict the half-lives of xenobiotics in humans using data obtained from rats. The present investigation was conducted to compare the performance of our published models against a common dataset obtained by merging the two sets of rat versus human half-life (hHL) data previously used by each laboratory. After combining data, mathematical analyses were undertaken by deploying both of our previous models, namely the use of an empirical algorithm based on a best-fit model and the use of rat-to-human liver blood flow ratios as a half-life correction factor. Both qualitative and quantitative analyses were performed, as well as evaluation of the impact of molecular properties on predictability. The merged dataset was remarkably diverse with respect to physiochemical and pharmacokinetic (PK) properties. Application of both models revealed similar predictability, depending upon the measure of stipulated accuracy. Certain molecular features, particularly rotatable bond count and pK(a), appeared to influence the accuracy of prediction. This collaborative effort has resulted in an improved understanding and appreciation of the value of rats to serve as a surrogate for the prediction of xenobiotic half-lives in humans when clinical pharmacokinetic studies are not possible or practicable.

  3. SPE-IMS-MS: An automated platform for sub-sixty second surveillance of endogenous metabolites and xenobiotics in biofluids

    DOE PAGES

    Zhang, Xing; Romm, Michelle; Zheng, Xueyun; ...

    2016-12-29

    Characterization of endogenous metabolites and xenobiotics is essential to deconvoluting the genetic and environmental causes of disease. However, surveillance of chemical exposure and disease-related changes in large cohorts requires an analytical platform that offers rapid measurement, high sensitivity, efficient separation, broad dynamic range, and application to an expansive chemical space. Here in this article, we present a novel platform for small molecule analyses that addresses these requirements by combining solid-phase extraction with ion mobility spectrometry and mass spectrometry (SPE-IMS-MS). This platform is capable of performing both targeted and global measurements of endogenous metabolites and xenobiotics in human biofluids with highmore » reproducibility (CV ≤ 3%), sensitivity (LODs in the pM range in biofluids) and throughput (10-s sample-to-sample duty cycle). We report application of this platform to the analysis of human urine from patients with and without type 1 diabetes, where we observed statistically significant variations in the concentration of disaccharides and previously unreported chemical isomers. Lastly, this SPE-IMS-MS platform overcomes many of the current challenges of large-scale metabolomic and exposomic analyses and offers a viable option for population and patient cohort screening in an effort to gain insights into disease processes and human environmental chemical exposure.« less

  4. SPE-IMS-MS: An automated platform for sub-sixty second surveillance of endogenous metabolites and xenobiotics in biofluids.

    PubMed

    Zhang, Xing; Romm, Michelle; Zheng, Xueyun; Zink, Erika M; Kim, Young-Mo; Burnum-Johnson, Kristin E; Orton, Daniel J; Apffel, Alex; Ibrahim, Yehia M; Monroe, Matthew E; Moore, Ronald J; Smith, Jordan N; Ma, Jian; Renslow, Ryan S; Thomas, Dennis G; Blackwell, Anne E; Swinford, Glenn; Sausen, John; Kurulugama, Ruwan T; Eno, Nathan; Darland, Ed; Stafford, George; Fjeldsted, John; Metz, Thomas O; Teeguarden, Justin G; Smith, Richard D; Baker, Erin S

    2016-12-01

    Characterization of endogenous metabolites and xenobiotics is essential to deconvoluting the genetic and environmental causes of disease. However, surveillance of chemical exposure and disease-related changes in large cohorts requires an analytical platform that offers rapid measurement, high sensitivity, efficient separation, broad dynamic range, and application to an expansive chemical space. Here, we present a novel platform for small molecule analyses that addresses these requirements by combining solid-phase extraction with ion mobility spectrometry and mass spectrometry (SPE-IMS-MS). This platform is capable of performing both targeted and global measurements of endogenous metabolites and xenobiotics in human biofluids with high reproducibility (CV 6 3%), sensitivity (LODs in the pM range in biofluids) and throughput (10-s sample-to-sample duty cycle). We report application of this platform to the analysis of human urine from patients with and without type 1 diabetes, where we observed statistically significant variations in the concentration of disaccharides and previously unreported chemical isomers. This SPE-IMS-MS platform overcomes many of the current challenges of large-scale metabolomic and exposomic analyses and offers a viable option for population and patient cohort screening in an effort to gain insights into disease processes and human environmental chemical exposure.

  5. SPE-IMS-MS: An automated platform for sub-sixty second surveillance of endogenous metabolites and xenobiotics in biofluids

    PubMed Central

    Zhang, Xing; Romm, Michelle; Zheng, Xueyun; Zink, Erika M.; Kim, Young-Mo; Burnum-Johnson, Kristin E.; Orton, Daniel J.; Apffel, Alex; Ibrahim, Yehia M.; Monroe, Matthew E.; Moore, Ronald J.; Smith, Jordan N.; Ma, Jian; Renslow, Ryan S.; Thomas, Dennis G.; Blackwell, Anne E.; Swinford, Glenn; Sausen, John; Kurulugama, Ruwan T.; Eno, Nathan; Darland, Ed; Stafford, George; Fjeldsted, John; Metz, Thomas O.; Teeguarden, Justin G.; Smith, Richard D.; Baker, Erin S.

    2017-01-01

    Characterization of endogenous metabolites and xenobiotics is essential to deconvoluting the genetic and environmental causes of disease. However, surveillance of chemical exposure and disease-related changes in large cohorts requires an analytical platform that offers rapid measurement, high sensitivity, efficient separation, broad dynamic range, and application to an expansive chemical space. Here, we present a novel platform for small molecule analyses that addresses these requirements by combining solid-phase extraction with ion mobility spectrometry and mass spectrometry (SPE-IMS-MS). This platform is capable of performing both targeted and global measurements of endogenous metabolites and xenobiotics in human biofluids with high reproducibility (CV 6 3%), sensitivity (LODs in the pM range in biofluids) and throughput (10-s sample-to-sample duty cycle). We report application of this platform to the analysis of human urine from patients with and without type 1 diabetes, where we observed statistically significant variations in the concentration of disaccharides and previously unreported chemical isomers. This SPE-IMS-MS platform overcomes many of the current challenges of large-scale metabolomic and exposomic analyses and offers a viable option for population and patient cohort screening in an effort to gain insights into disease processes and human environmental chemical exposure. PMID:29276770

  6. 34 CFR 86.100 - What must the IHE's drug prevention program include?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., or distribution of illicit drugs and alcohol by students and employees on its property or as part of... Federal law for the unlawful possession or distribution of illicit drugs and alcohol; (3) A description of the health risks associated with the use of illicit drugs and the abuse of alcohol; (4) A description...

  7. Screening and monitoring microbial xenobiotics' biodegradation by rapid, inexpensive and easy to perform microplate UV-absorbance measurements.

    PubMed

    Herzog, Bastian; Lemmer, Hilde; Horn, Harald; Müller, Elisabeth

    2014-02-22

    Evaluation of xenobiotics biodegradation potential, shown here for benzotriazoles (corrosion inhibitors) and sulfamethoxazole (sulfonamide antibiotic) by microbial communities and/or pure cultures normally requires time intensive and money consuming LC/GC methods that are, in case of laboratory setups, not always needed. The usage of high concentrations to apply a high selective pressure on the microbial communities/pure cultures in laboratory setups, a simple UV-absorbance measurement (UV-AM) was developed and validated for screening a large number of setups, requiring almost no preparation and significantly less time and money compared to LC/GC methods. This rapid and easy to use method was evaluated by comparing its measured values to LC-UV and GC-MS/MS results. Furthermore, its application for monitoring and screening unknown activated sludge communities (ASC) and mixed pure cultures has been tested and approved to detect biodegradation of benzotriazole (BTri), 4- and 5-tolyltriazole (4-TTri, 5-TTri) as well as SMX. In laboratory setups, xenobiotics concentrations above 1.0 mg L(-1) without any enrichment or preparation could be detected after optimization of the method. As UV-AM does not require much preparatory work and can be conducted in 96 or even 384 well plate formats, the number of possible parallel setups and screening efficiency was significantly increased while analytic and laboratory costs were reduced to a minimum.

  8. Confirmation of high-throughput screening data and novel mechanistic insights into VDR-xenobiotic interactions by orthogonal assays.

    PubMed

    Mahapatra, Debabrata; Franzosa, Jill A; Roell, Kyle; Kuenemann, Melaine Agnes; Houck, Keith A; Reif, David M; Fourches, Denis; Kullman, Seth W

    2018-06-11

    High throughput screening (HTS) programs have demonstrated that the Vitamin D receptor (VDR) is activated and/or antagonized by a wide range of structurally diverse chemicals. In this study, we examined the Tox21 qHTS data set generated against VDR for reproducibility and concordance and elucidated functional insights into VDR-xenobiotic interactions. Twenty-one potential VDR agonists and 19 VDR antagonists were identified from a subset of >400 compounds with putative VDR activity and examined for VDR functionality utilizing select orthogonal assays. Transient transactivation assay (TT) using a human VDR plasmid and Cyp24 luciferase reporter construct revealed 20/21 active VDR agonists and 18/19 active VDR antagonists. Mammalian-2-hybrid assay (M2H) was then used to evaluate VDR interactions with co-activators and co-regulators. With the exception of a select few compounds, VDR agonists exhibited significant recruitment of co-regulators and co-activators whereas antagonists exhibited considerable attenuation of recruitment by VDR. A unique set of compounds exhibiting synergistic activity in antagonist mode and no activity in agonist mode was identified. Cheminformatics modeling of VDR-ligand interactions were conducted and revealed selective ligand VDR interaction. Overall, data emphasizes the molecular complexity of ligand-mediated interactions with VDR and suggest that VDR transactivation may be a target site of action for diverse xenobiotics.

  9. [Steroid and xenobiotic receptor (SXR), multidrug resistance gene (MDR1) and GSTs, SULTs and CYP polymorphism expression in invasive bladder cancer, analysis of their expression and correlation with other prognostic factors].

    PubMed

    Rioja Zuazu, J; Bandrés Elizalde, E; Rosell Costa, D; Rincón Mayans, A; Zudaire Bergera, J; Gil Sanz, M J; Rioja Sanz, L A; García Foncillas, J; Berián Polo, J M

    2007-01-01

    Steroid and Xenobiotic Receptor (SXR) has demonstrated its activation by numerous drugs, including cytochrome P450 potent inducers like rifampicina or cotrimazol. The role of SXR is well known, and lies regulating in a positive manner cytochrome P450 3A4 (CYP3A4) transcription and the multidrug resistance gene (MDR1), it's considered a key in the xenobiotic detoxification mechanism, being involved in all phases of the detoxification process. Enzymes involved in Policyclic Aromatic hidrocarbures (PAH) metabolism and degradation are polymorphic in humans, including glutation S-transferases (GSTs), N-acetiltransferases (NATs), sulfotransferases (SULTs)1A1 and cytochrome p450 (CYP)1B1. The objectives we've planned are: 1. Analyze the expression of the transcription factor SXR and MDR1 in bladder by means of RT-PCR real time, both in normal bladder and in tumoral bladder. 2. Analyze the relation between clinical and pathological factors with the expression of SXR and MDR1. 3. Analyze the expression of the polymorphims CYP1B1, GSTM1 GSTT1 and SULT1A1 and their correlation with different clinic-pathological and molecular factors. In a prospective way the size of the sample was estimated. In 67 patients from two institutions (Hospital Universitario Miguel Servet (49 HUMS) and Clinica Universitaria de Navarra (18 CUN)), diagnosed of invasive bladder cancer and treated by means of radical cystectomy, were determined the expression of both SXR and MDR1 by means of real time PCR, as well as the polymorphisms CYP1B1, GSTM1 GSTT1 y SULT1A1 by means of RFLP (Restriction fragment length polymorphism). Correlations with other prognostic factors by contingency tables were performed. Average follow up was 23.7 months with a median of 28.26 months. Of the 67 patients studied, 31 patients (46.3) presented disease progression, in form of local recurrence or in distant metastasis or both. With a average time to progression of 12.4 months and a median of 10 months, with a range of 1

  10. Generation of Hepatocytes from Pluripotent Stem Cells for Drug Screening and Developmental Modeling.

    PubMed

    Gieseck, Richard L; Vallier, Ludovic; Hannan, Nicholas R F

    2015-01-01

    Hepatocytes produced from the differentiation of human pluripotent stem cells can be used to study human development and liver disease, to investigate the toxicological response of novel drug candidates, and as an alternative source of primary cells for transplantation therapies. Here, we describe a method to produce hepatocytes by differentiating human pluripotent stem cells into definitive endoderm, patterning definitive endoderm into anterior definitive endoderm, specifying anterior definitive endoderm into hepatic endoderm, and differentiating hepatic endoderm into immature hepatocytes. These cells are further matured in either two-dimensional or three-dimensional culture conditions to produce cells capable of metabolizing xenobiotics and generating liver-specific proteins, such as albumin and alpha 1 antitrypsin.

  11. Phase I to II cross-induction of xenobiotic metabolizing enzymes: a feedforward control mechanism for potential hormetic responses.

    PubMed

    Zhang, Qiang; Pi, Jingbo; Woods, Courtney G; Andersen, Melvin E

    2009-06-15

    Hormetic responses to xenobiotic exposure likely occur as a result of overcompensation by the homeostatic control systems operating in biological organisms. However, the mechanisms underlying overcompensation that leads to hormesis are still unclear. A well-known homeostatic circuit in the cell is the gene induction network comprising phase I, II and III metabolizing enzymes, which are responsible for xenobiotic detoxification, and in many cases, bioactivation. By formulating a differential equation-based computational model, we investigated in this study whether hormesis can arise from the operation of this gene/enzyme network. The model consists of two feedback and one feedforward controls. With the phase I negative feedback control, xenobiotic X activates nuclear receptors to induce cytochrome P450 enzyme, which bioactivates X into a reactive metabolite X'. With the phase II negative feedback control, X' activates transcription factor Nrf2 to induce phase II enzymes such as glutathione S-transferase and glutamate cysteine ligase, etc., which participate in a set of reactions that lead to the metabolism of X' into a less toxic conjugate X''. The feedforward control involves phase I to II cross-induction, in which the parent chemical X can also induce phase II enzymes directly through the nuclear receptor and indirectly through transcriptionally upregulating Nrf2. As a result of the active feedforward control, a steady-state hormetic relationship readily arises between the concentrations of the reactive metabolite X' and the extracellular parent chemical X to which the cell is exposed. The shape of dose-response evolves over time from initially monotonically increasing to J-shaped at the final steady state-a temporal sequence consistent with adaptation-mediated hormesis. The magnitude of the hormetic response is enhanced by increases in the feedforward gain, but attenuated by increases in the bioactivation or phase II feedback loop gains. Our study suggests a

  12. Draft Genome Sequence of Paenibacillus sp. Strain DMB20, Isolated from Alang Ship-Breaking Yard, Which Harbors Genes for Xenobiotic Degradation

    PubMed Central

    Shah, Binal; Jain, Kunal; Patel, Namrata; Pandit, Ramesh; Patel, Anand; Joshi, Chaitanya G.

    2015-01-01

    Paenibacillus sp. strain DMB20, in cometabolism with other Proteobacteria and Firmicutes, exhibits azoreduction of textile dyes. Here, we report the draft genome sequence of this bacterium, consisting of 6,647,181 bp with 7,668 coding sequences (CDSs). The data presented highlight multiple sets of functional genes associated with xenobiotic compound degradation. PMID:26067950

  13. Stages in reproduction particularly vulnerable to xenobiotic hazards and nutritional deficits.

    PubMed

    House, S

    2000-01-01

    Biochemical research has identified many failures in reproductive processes with specific nutrient deficits, xenobiotics and some infectious illnesses. This has led to some effective safeguards. During meiosis and fertilization, as genetic material divides and rearranges, it is exposed and open to mutation. A nutritionally unfavourable environment is a major risk factor. At stages of rapid cell division, differentiation and organisation, as in the embryo and later in the fetal brain, the child's survival, completeness and future health and ability are at stake. From months before conception, reproduction needs preparing for, especially with today's environmental pollution, even entering the foodchain. Care from before conception can contribute not only to the child's healthy basis for life, full development of brain, eyesight and other complex attributes, but also to the health of at least the subsequent generation. Since the female baby's oocytes are being formed while she is still in the womb, the grandmother's nutritional status, around the time of conceiving a daughter, can permanently affect a grandchild. Recent insights into evolution, particularly of the brain, give us fresh indications of dietary needs to fulfil human potential for health and acuity. Despite the hazards, nature is remarkably successful. This paper is not designed to alarm but to help attainment of full genetic potential. With healthy parents serious malformations are a low percentage. The numbers of babies with avoidable disorders, however, calls urgently for action, especially in our own inner cities and in developing countries where there is inadequate nutrition. Action will more than justify itself, including financially. It will reward handsomely.

  14. Sample preparation and data interpretation procedures for the examination of xenobiotic compounds in skin by indirect imaging MALDI-MS

    NASA Astrophysics Data System (ADS)

    Prideaux, Brendan; Atkinson, Sally J.; Carolan, Vikki A.; Morton, Jacqueline; Clench, Malcolm R.

    2007-02-01

    Aspects of the indirect examination of xenobiotic distribution on the surface of and within skin sections by imaging matrix assisted laser desorption ionisation mass spectrometry (MALDI-MS) have been examined. A solvent assisted blotting technique previously developed for the examination of the absorption of agrochemicals into leaves has been examined for the analysis of the distribution of hydrocortisone on the surface of skin. It was found that by careful control of the extraction and blotting procedure an 80-fold sensitivity improvement could by obtained over dry blotting with only 10% lateral diffusion of the image. However, in contrast it was found that the use of a hydrophobic blotting membrane was more suitable for the examination of the transdermal absorption of the pesticide chlorpyrifos. The potential of incorporating a derivatisation step into the solvent assisted blotting procedure was investigated by blotting isocyanate treated skin onto a methanol soaked blotting membrane. This served the dual purpose of derivatising the isocyanate to a stable substituted urea derivative and extracting it from the skin. Preliminary data indicate that this approach may have some merit for field sampling for such compound and clearly derivatisation also offers the potential for sensitivity enhancements. Finally, the use of principal components analysis with an ion species specific normalisation procedure is proposed to identify regions of drug treated skin where the ion abundance of the compound of interest is low.

  15. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Thornton-Manning, J.R.; Hotchkiss, J.A.; Ding, Xinxin

    The nasal mucosa, the first tissue of contact for inhaled xenobiotics, possesses substantial enobiotic-metabolizing capacti. Enzymes of the nasal cavity may metabolize xenobiotics to innocuous, more water-soluble compounds that are eliminated from the body, or they may bioactivate them to toxic metabolites. These toxic metabolites may find to cellular macromolecules in the nasal cavity or be transported to other parts of the body where they may react. Nasal carcinogenesis in rodents often results from bioactivation of xenobiotics. The increased incidences of nasal tumors associated with certain occupations suggest that xenobiotic bioactivation may be important in human nasal cancer etiology, asmore » well. The increasing popularity of the nose as a route of drug administration makes information concerning nasal drug metabolism and disposition vital to accomplish therapeutic goals. For these reasons, the study of xenobiotic-met abolizing capacity of the nasal cavity is an important area of health-related research. In the present study, we have confirmed the presence of CYP2A6 mRNA in human respiratory mucosa.« less

  16. Precision-cut intestinal slices: alternative model for drug transport, metabolism, and toxicology research.

    PubMed

    Li, Ming; de Graaf, Inge A M; Groothuis, Geny M M

    2016-01-01

    The absorption, distribution, metabolism, excretion and toxicity (ADME-tox) processes of drugs are of importance and require preclinical investigation intestine in addition to the liver. Various models have been developed for prediction of ADME-tox in the intestine. In this review, precision-cut intestinal slices (PCIS) are discussed and highlighted as model for ADME-tox studies. This review provides an overview of the applications and an update of the most recent research on PCIS as an ex vivo model to study the transport, metabolism and toxicology of drugs and other xenobiotics. The unique features of PCIS and the differences with other models as well as the translational aspects are also discussed. PCIS are a simple, fast, and reliable ex vivo model for drug ADME-tox research. Therefore, PCIS are expected to become an indispensable link in the in vitro-ex vivo-in vivo extrapolation, and a bridge in translation of animal data to the human situation. In the future, this model may be helpful to study the effects of interorgan interactions, intestinal bacteria, excipients and drug formulations on the ADME-tox properties of drugs. The optimization of culture medium and the development of a (cryo)preservation technique require more research.

  17. Quantitative High-Throughput Identification of Drugs as Modulators of Human Constitutive Androstane Receptor

    PubMed Central

    Lynch, Caitlin; Zhao, Jinghua; Huang, Ruili; Xiao, Jingwei; Li, Linhao; Heyward, Scott; Xia, Menghang; Wang, Hongbing

    2015-01-01

    The constitutive androstane receptor (CAR, NR1I3) plays a key role in governing the transcription of numerous hepatic genes that involve xenobiotic metabolism/clearance, energy homeostasis, and cell proliferation. Thus, identification of novel human CAR (hCAR) modulators may not only enhance early prediction of drug-drug interactions but also offer potentially novel therapeutics for diseases such as metabolic disorders and cancer. In this study, we have generated a double stable cell line expressing both hCAR and a CYP2B6-driven luciferase reporter for quantitative high-throughput screening (qHTS) of hCAR modulators. Approximately 2800 compounds from the NIH Chemical Genomics Center Pharmaceutical Collection were screened employing both the activation and deactivation modes of the qHTS. Activators (115) and deactivators (152) of hCAR were identified from the primary qHTS, among which 10 agonists and 10 antagonists were further validated in the physiologically relevant human primary hepatocytes for compound-mediated hCAR nuclear translocation and target gene expression. Collectively, our results reveal that hCAR modulators can be efficiently identified through this newly established qHTS assay. Profiling drug collections for hCAR activity would facilitate the prediction of metabolism-based drug-drug interactions, and may lead to the identification of potential novel therapeutics. PMID:25993555

  18. Chemotherapy of Rodent Malaria. Evaluation of Drug Action against Normal and Resistant Strains including Exo-Erythrocytic Stages.

    DTIC Science & Technology

    1979-10-01

    AD-RI35 058 CHEMOTHERAPY’OF RODENT MALARIA EVALUATION OF DRUG I/i ACTION AGAINST NORMAL R-.(U) LIVERPOQL SCHOOL OF TROPICAL MEDICINE ENGLAND) DEPT OF...PARS N PETERSUNCLASSIFIED OCT 79 DANDi?79 6 -G94 57 F/ 6 6 /15117EhEEohEohhhiE *flfl 4L 2 Q~ -8 hi 36 11125 LA 11.6 MICROCOPY RESOLUTION TEST CHART...NATIONAL BUREAU OF STANDARDS- 1963-A I" CHEMOTHERAPY RODENT MALARIA EVALUATION OF DRUG AC ON AGAINST NORMAL AND RESISTANT STRAINS INCLUDING EXO

  19. Hallucinogens and Dissociative Drugs, Including LSD, PCP, Ketamine, Dextromethorphan. National Institute on Drug Abuse Research Report Series.

    ERIC Educational Resources Information Center

    National Inst. on Drug Abuse (DHHS/PHS), Rockville, MD.

    Research is developing a clearer picture of the dangers of mind-altering drugs. The goal of this report is to present the latest information to providers to help them strengthen their prevention and treatment efforts. A description is presented of dissociative drugs, and consideration is given as to why people take hallucinogens. The physical…

  20. Decreased detoxification genes and genome size make the human body louse an efficient model to study xenobiotic metabolism

    PubMed Central

    Lee, Si Hyeock; Kang, Jae Soon; Min, Jee Sun; Yoon, Kyong Sup; Strycharz, Joseph P.; Johnson, Reed; Mittapalli, Omprakash; Margam, Venu M.; Sun, Weilin; Li, Hong-Mei; Xie, Jun; Wu, Jing; Kirkness, Ewen F.; Berenbaum, May R.; Pittendrigh, Barry R.; Clark, J. Marshall

    2010-01-01

    The human body louse, Pediculus humanus humanus, has one of the smallest insect genomes, containing ~10,775 annotated genes (Kirkness et al. 2010). Annotation of detoxification [cytochrome P450 monooxygenase (P450), glutathione-S-transferase (GST), esterase (Est), and ATP-binding cassette transporter (ABC transporter)] genes revealed that they are dramatically reduced in P. h. humanus compared to other insects except for Apis mellifera. There are 37 P450, 13 GST and 17 Est genes present in P. h. humanus, approximately half of that found in Drosophila melanogaster and Anopheles gambiae. The number of putatively functional ABC transporter genes in P. h. humanus and A. mellifera are the same (36) but both have fewer than An. gambiae (44) or D. melanogaster (65). The reduction of detoxification genes in P. h. humanus may be due to their simple life history, where they do not encounter a wide variety of xenobiotics. Neuronal component genes are highly conserved across different insect species as expected due to their critical function. Although reduced in number, P. h. humanus still retains at least a minimum repertoire of genes known to confer metabolic or toxicokinetic resistance to xenobiotics (e.g., Cyp3 clade P450s, Delta GSTs, B clade Ests and B/C subfamily ABC transporters), suggestive of its high potential for resistance development. PMID:20561088

  1. Decreased detoxification genes and genome size make the human body louse an efficient model to study xenobiotic metabolism.

    PubMed

    Lee, S H; Kang, J S; Min, J S; Yoon, K S; Strycharz, J P; Johnson, R; Mittapalli, O; Margam, V M; Sun, W; Li, H-M; Xie, J; Wu, J; Kirkness, E F; Berenbaum, M R; Pittendrigh, B R; Clark, J M

    2010-10-01

    The human body louse, Pediculus humanus humanus, has one of the smallest insect genomes, containing ∼10 775 annotated genes. Annotation of detoxification [cytochrome P450 monooxygenase (P450), glutathione-S-transferase (GST), esterase (Est) and ATP-binding cassette transporter (ABC transporter)] genes revealed that they are dramatically reduced in P. h. humanus compared to other insects except for Apis mellifera. There are 37 P450, 13 GST and 17 Est genes present in P. h. humanus, approximately half the number found in Drosophila melanogaster and Anopheles gambiae. The number of putatively functional ABC transporter genes in P. h. humanus and Ap. mellifera are the same (36) but both have fewer than An. gambiae (44) or Dr. melanogaster (65). The reduction of detoxification genes in P. h. humanus may be a result of this louse's simple life history, in which it does not encounter a wide variety of xenobiotics. Neuronal component genes are highly conserved across different insect species as expected because of their critical function. Although reduced in number, P. h. humanus still retains at least a minimum repertoire of genes known to confer metabolic or toxicokinetic resistance to xenobiotics (eg Cyp3 clade P450s, Delta GSTs, B clade Ests and B/C subfamily ABC transporters), suggestive of its high potential for resistance development. © 2010 The Authors. Insect Molecular Biology © 2010 The Royal Entomological Society.

  2. Membrane Phospholipid Augments Cytochrome P4501a Enzymatic Activity by Modulating Structural Conformation during Detoxification of Xenobiotics

    PubMed Central

    Ghosh, Manik C.; Ray, Arun K.

    2013-01-01

    Cytochrome P450 is a superfamily of membrane-bound hemoprotein that gets involved with the degradation of xenobiotics and internal metabolites. Accumulated body of evidence indicates that phospholipids play a crucial role in determining the enzymatic activity of cytochrome P450 in the microenvironment by modulating its structure during detoxification; however, the structure-function relationship of cytochrome P4501A, a family of enzymes responsible for degrading lipophilic aromatic hydrocarbons, is still not well defined. Inducibility of cytochrome P4501A in cultured catfish hepatocytes in response to carbofuran, a widely used pesticide around the world, was studied earlier in our laboratory. In this present investigation, we observed that treating catfish with carbofuran augmented total phospholipid in the liver. We examined the role of phospholipid on the of cytochrome P4501A-marker enzyme which is known as ethoxyresorufin-O-deethylase (EROD) in the context of structure and function. We purified the carbofuran-induced cytochrome P4501A protein from catfish liver. Subsequently, we examined the enzymatic activity of purified P4501A protein in the presence of phospholipid, and studied how the structure of purified protein was influenced in the phospholipid environment. Membrane phospholipid appeared to accelerate the enzymatic activity of EROD by changing its structural conformation and thus controlling the detoxification of xenobiotics. Our study revealed the missing link of how the cytochrome P450 restores its enzymatic activity by changing its structural conformation in the phospholipid microenvironment. PMID:23469105

  3. Membrane phospholipid augments cytochrome P4501a enzymatic activity by modulating structural conformation during detoxification of xenobiotics.

    PubMed

    Ghosh, Manik C; Ray, Arun K

    2013-01-01

    Cytochrome P450 is a superfamily of membrane-bound hemoprotein that gets involved with the degradation of xenobiotics and internal metabolites. Accumulated body of evidence indicates that phospholipids play a crucial role in determining the enzymatic activity of cytochrome P450 in the microenvironment by modulating its structure during detoxification; however, the structure-function relationship of cytochrome P4501A, a family of enzymes responsible for degrading lipophilic aromatic hydrocarbons, is still not well defined. Inducibility of cytochrome P4501A in cultured catfish hepatocytes in response to carbofuran, a widely used pesticide around the world, was studied earlier in our laboratory. In this present investigation, we observed that treating catfish with carbofuran augmented total phospholipid in the liver. We examined the role of phospholipid on the of cytochrome P4501A-marker enzyme which is known as ethoxyresorufin-O-deethylase (EROD) in the context of structure and function. We purified the carbofuran-induced cytochrome P4501A protein from catfish liver. Subsequently, we examined the enzymatic activity of purified P4501A protein in the presence of phospholipid, and studied how the structure of purified protein was influenced in the phospholipid environment. Membrane phospholipid appeared to accelerate the enzymatic activity of EROD by changing its structural conformation and thus controlling the detoxification of xenobiotics. Our study revealed the missing link of how the cytochrome P450 restores its enzymatic activity by changing its structural conformation in the phospholipid microenvironment.

  4. Draft Genome Sequence of Paenibacillus sp. Strain DMB20, Isolated from Alang Ship-Breaking Yard, Which Harbors Genes for Xenobiotic Degradation.

    PubMed

    Shah, Binal; Jain, Kunal; Patel, Namrata; Pandit, Ramesh; Patel, Anand; Joshi, Chaitanya G; Madamwar, Datta

    2015-06-11

    Paenibacillus sp. strain DMB20, in cometabolism with other Proteobacteria and Firmicutes, exhibits azoreduction of textile dyes. Here, we report the draft genome sequence of this bacterium, consisting of 6,647,181 bp with 7,668 coding sequences (CDSs). The data presented highlight multiple sets of functional genes associated with xenobiotic compound degradation. Copyright © 2015 Shah et al.

  5. Overview of Drug Delivery Methods in Exotics, Including Their Anatomic and Physiologic Considerations.

    PubMed

    Coutant, Thomas; Vergneau-Grosset, Claire; Langlois, Isabelle

    2018-05-01

    Drug delivery to exotic animals may be extrapolated from domestic animals, but some physiologic and anatomic differences complicate treatment administration. Knowing these differences enables one to choose optimal routes for drug delivery. This review provides practitioners with a detailed review of the currently reported methods used for drug delivery of various medications in the most common exotic animal species. Exotic animal peculiarities that are relevant for drug administration are discussed in the text and outlined in tables and boxes to help the reader easily find targeted information. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. Identification of novel cytochrome P450s in the Acari

    USDA-ARS?s Scientific Manuscript database

    Cytochrome P450s are the major phase I drug metabolising enzymes found in most organisms, including arthropods. Much of the work within the area of xenobiotic metabolism in this group of animals has centered around mosquito species, e.g. Anopheles gambiae and Culex quinquefasciatus, due to their rol...

  7. 38 CFR 48.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... drug-free awareness program? 48.215 Section 48.215 Pensions, Bonuses, and Veterans' Relief DEPARTMENT...

  8. 38 CFR 48.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... drug-free awareness program? 48.215 Section 48.215 Pensions, Bonuses, and Veterans' Relief DEPARTMENT...

  9. 38 CFR 48.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... drug-free awareness program? 48.215 Section 48.215 Pensions, Bonuses, and Veterans' Relief DEPARTMENT...

  10. 38 CFR 48.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... drug-free awareness program? 48.215 Section 48.215 Pensions, Bonuses, and Veterans' Relief DEPARTMENT...

  11. 38 CFR 48.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free workplace; (c... that you may impose upon them for drug abuse violations occurring in the workplace. ... drug-free awareness program? 48.215 Section 48.215 Pensions, Bonuses, and Veterans' Relief DEPARTMENT...

  12. 36 CFR 1212.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... drug-free awareness program? 1212.215 Section 1212.215 Parks, Forests, and Public Property NATIONAL...

  13. 36 CFR 1212.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... drug-free awareness program? 1212.215 Section 1212.215 Parks, Forests, and Public Property NATIONAL...

  14. 36 CFR 1212.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... drug-free awareness program? 1212.215 Section 1212.215 Parks, Forests, and Public Property NATIONAL...

  15. 36 CFR 1212.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... drug-free awareness program? 1212.215 Section 1212.215 Parks, Forests, and Public Property NATIONAL...

  16. COMMENTS ON "EFFECT OF PRENATAL EXPOSURE OF DELTAMETHRIN ON THE ONTOGENY OF XENOBIOTIC METABOLIZING CYTOCHROME P450S IN THE BRAIN AND LIVER OF OFFSPRINGS.

    EPA Science Inventory

    Comments on: Effect of prenatal exposure of deltamethrin on the ontogeny of xenobiotic metabolizing cytochrome P450s in the brain and liver of offsprings [Johri et al. Toxicol Appl Pharmacol. 214:279-289, 2006]

    Johri and colleagues recently reported that maternal exposur...

  17. Molecular insights into the association of obesity with breast cancer risk: relevance to xenobiotic metabolism and CpG island methylation of tumor suppressor genes.

    PubMed

    Naushad, Shaik Mohammad; Hussain, Tajamul; Al-Attas, Omar S; Prayaga, Aruna; Digumarti, Raghunadha Rao; Gottumukkala, Suryanarayana Raju; Kutala, Vijay Kumar

    2014-07-01

    Obesity, genetic polymorphisms of xenobiotic metabolic pathway, hypermethylation of tumor suppressor genes, and hypomethylation of proapoptotic genes are known to be independent risk factors for breast cancer. The objective of this study is to evaluate the combined effect of these environmental, genetic, and epigenetic risk factors on the susceptibility to breast cancer. PCR-RFLP and multiplex PCR were used for the genetic analysis of six variants of xenobiotic metabolic pathway. Methylation-specific PCR was used for the epigenetic analysis of four genetic loci. Multifactor dimensionality reduction analysis revealed a significant interaction between the body mass index (BMI) and catechol-O-methyl transferase H108L variant alone or in combination with cytochrome P450 (CYP) 1A1m1 variant. Women with "Luminal A" breast cancer phenotype had higher BMI compared to other phenotypes and healthy controls. There was no association between the BMI and tumor grade. The post-menopausal obese women exhibited lower glutathione levels. BMI showed a positive association with the methylation of extracellular superoxide dismutase (r = 0.21, p < 0.05), Ras-association (RalGDS/AF-6) domain family member 1 (RASSF1A) (r = 0.31, p < 0.001), and breast cancer type 1 susceptibility protein (r = 0.19, p < 0.05); and inverse association with methylation of BNIP3 (r = -0.48, p < 0.0001). To conclude based on these results, obesity increases the breast cancer susceptibility by two possible mechanisms: (i) by interacting with xenobiotic genetic polymorphisms in inducing increased oxidative DNA damage and (ii) by altering the methylome of several tumor suppressor genes.

  18. Substrate specificity of xenobiotic metabolizing esterases in the liver of two catfish species

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jaiswal, R.G.; Huang, T.L.; Obih, P.O.

    1994-12-31

    The preliminary studies were conducted on the characterization of substrate specificity in the liver microsomes and cytosol of two catfish species, Ictalurus punctatus and Ictalurus natalie. A series of five esters of p-nitrophenol were used as calorimetric substrates to assay the carboxylesterases. The substrate specificity of liver microsomal and cytosolic carboxylesterases were remarkably different from each other. The valerate ester of p-nitrophenol was most rapidly hydrolyzed by the microsomal carboxylesterases, whereas the prioponate ester was the best substrate for cytosolic carboxylesterases. The Ictalurus natalie catfish species were obtained from the Devil Swamp site of the Mississippi River Basin which ismore » known to be heavily contaminated with toxic and hazardous industrial wastes. These results will be discussed in relation to the responses of xenobiotic metabolizing esterases to environmental pollutants and their possible use as biomarkers.« less

  19. Cytochrome P450 Monooxygenases for Fatty Acids and Xenobiotics in Marine Macroalgae1

    PubMed Central

    Pflugmacher, Stephan; Sandermann, Heinrich

    1998-01-01

    The metabolism of xenobiotics has mainly been investigated in higher plant species. We studied them in various marine macroalgae of the phyla Chlorophyta, Chromophyta, and Rhodophyta. Microsomes contained high oxidative activities for known cytochrome (Cyt) P450 substrates (fatty acids, cinnamic acid, 3- and 4-chlorobiphenyl, 2,3-dichlorobiphenyl, and isoproturon; up to 54 pkat/mg protein). The presence of Cyt P450 (approximately 50 pmol/mg protein) in microsomes of the three algal families was demonstrated by CO-difference absorption spectra. Intact algal tissue converted 3-chlorobiphenyl to the same monohydroxy-metabolite formed in vitro. This conversion was 5-fold stimulated upon addition of phenobarbital, and was abolished by the known P450 inhibitor, 1-aminobenzotriazole. It is concluded that marine macroalgae contain active species of Cyt P450 and could act as a metabolic sink for marine pollutants. PMID:9576781

  20. Combination of microautoradiography and fluorescence in situ hybridization for identification of microorganisms degrading xenobiotic contaminants.

    PubMed

    Yang, Yanru; Zarda, Annatina; Zeyer, Josef

    2003-12-01

    One of the central topics in environmental bioremediation research is to identify microorganisms that are capable of degrading the contaminants of interest. Here we report application of combined microautoradiography (MAR) and fluorescence in situ hybridization (FISH). The method has previously been used in a number of systems; however, here we demonstrate its feasibility in studying the degradation of xenobiotic compounds. With a model system (coculture of Pseudomonas putida B2 and Sphingomonas stygia incubated with [14C] o-nitrophenol), combination of MAR and FISH was shown to be able to successfully identify the microorganisms degrading o-nitrophenol. Compared with the conventional techniques, MAR-FISH allows fast and accurate identification of the microorganisms involved in environmental contaminant degradation.

  1. Killing them with kindness? In-hive medications may inhibit xenobiotic efflux transporters and endanger honey bees.

    PubMed

    Hawthorne, David J; Dively, Galen P

    2011-01-01

    Honey bees (Apis mellifera) have recently experienced higher than normal overwintering colony losses. Many factors have been evoked to explain the losses, among which are the presence of residues of pesticides and veterinary products in hives. Multiple residues are present at the same time, though most often in low concentrations so that no single product has yet been associated with losses. Involvement of a combination of residues to losses may however not be excluded. To understand the impact of an exposure to combined residues on honey bees, we propose a mechanism-based strategy, focusing here on Multi-Drug Resistance (MDR) transporters as mediators of those interactions. Using whole-animal bioassays, we demonstrate through inhibition by verapamil that the widely used organophosphate and pyrethroid acaricides coumaphos and τ-fluvalinate, and three neonicotinoid insecticides: imidacloprid, acetamiprid and thiacloprid are substrates of one or more MDR transporters. Among the candidate inhibitors of honey bee MDR transporters is the in-hive antibiotic oxytetracycline. Bees prefed oxytetracycline were significantly sensitized to the acaricides coumaphos and τ-fluvalinate, suggesting that the antibiotic may interfere with the normal excretion or metabolism of these pesticides. Many bee hives receive regular treatments of oxytetracycline and acaricides for prevention and treatment of disease and parasites. Our results suggest that seasonal co-application of these medicines to bee hives could increase the adverse effects of these and perhaps other pesticides. Our results also demonstrate the utility of a mechanism-based strategy. By identifying pesticides and apicultural medicines that are substrates and inhibitors of xenobiotic transporters we prioritize the testing of those chemical combinations most likely to result in adverse interactions.

  2. DrugBank: a knowledgebase for drugs, drug actions and drug targets

    PubMed Central

    Wishart, David S.; Knox, Craig; Guo, An Chi; Cheng, Dean; Shrivastava, Savita; Tzur, Dan; Gautam, Bijaya; Hassanali, Murtaza

    2008-01-01

    DrugBank is a richly annotated resource that combines detailed drug data with comprehensive drug target and drug action information. Since its first release in 2006, DrugBank has been widely used to facilitate in silico drug target discovery, drug design, drug docking or screening, drug metabolism prediction, drug interaction prediction and general pharmaceutical education. The latest version of DrugBank (release 2.0) has been expanded significantly over the previous release. With ∼4900 drug entries, it now contains 60% more FDA-approved small molecule and biotech drugs including 10% more ‘experimental’ drugs. Significantly, more protein target data has also been added to the database, with the latest version of DrugBank containing three times as many non-redundant protein or drug target sequences as before (1565 versus 524). Each DrugCard entry now contains more than 100 data fields with half of the information being devoted to drug/chemical data and the other half devoted to pharmacological, pharmacogenomic and molecular biological data. A number of new data fields, including food–drug interactions, drug–drug interactions and experimental ADME data have been added in response to numerous user requests. DrugBank has also significantly improved the power and simplicity of its structure query and text query searches. DrugBank is available at http://www.drugbank.ca PMID:18048412

  3. Transformation and Sorption of Illicit Drug Biomarkers in Sewer Systems: Understanding the Role of Suspended Solids in Raw Wastewater.

    PubMed

    Ramin, Pedram; Libonati Brock, Andreas; Polesel, Fabio; Causanilles, Ana; Emke, Erik; de Voogt, Pim; Plósz, Benedek Gy

    2016-12-20

    Sewer pipelines, although primarily designed for sewage transport, can also be considered as bioreactors. In-sewer processes may lead to significant variations of chemical loadings from source release points to the treatment plant influent. In this study, we assessed in-sewer utilization of growth substrates (primary metabolic processes) and transformation of illicit drug biomarkers (secondary metabolic processes) by suspended biomass. Sixteen drug biomarkers were targeted, including mephedrone, methadone, cocaine, heroin, codeine, and tetrahydrocannabinol (THC) and their major human metabolites. Batch experiments were performed under aerobic and anaerobic conditions using raw wastewater. Abiotic biomarker transformation and partitioning to suspended solids and reactor wall were separately investigated under both redox conditions. A process model was identified by combining and extending the Wastewater Aerobic/anaerobic Transformations in Sewers (WATS) model and Activated Sludge Model for Xenobiotics (ASM-X). Kinetic and stoichiometric model parameters were estimated using experimental data via the Bayesian optimization method DREAM (ZS) . Results suggest that biomarker transformation significantly differs from aerobic to anaerobic conditions, and abiotic conversion is the dominant mechanism for many of the selected substances. Notably, an explicit description of biomass growth during batch experiments was crucial to avoid significant overestimation (up to 385%) of aerobic biotransformation rate constants. Predictions of in-sewer transformation provided here can reduce the uncertainty in the estimation of drug consumption as part of wastewater-based epidemiological studies.

  4. Structural Insights into Drug Processing by Human Carboxylesterase 1: Tamoxifen, Mevastatin, and Inhibition by Benzil

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fleming, Christopher D.; Bencharit, Sompop; Edwards, Carol C.

    2010-07-19

    Human carboxylesterase 1 (hCE1) exhibits broad substrate specificity and is involved in xenobiotic processing and endobiotic metabolism. We present and analyze crystal structures of hCE1 in complexes with the cholesterol-lowering drug mevastatin, the breast cancer drug tamoxifen, the fatty acyl ethyl ester (FAEE) analogue ethyl acetate, and the novel hCE1 inhibitor benzil. We find that mevastatin does not appear to be a substrate for hCE1, and instead acts as a partially non-competitive inhibitor of the enzyme. Similarly, we show that tamoxifen is a low micromolar, partially non-competitive inhibitor of hCE1. Further, we describe the structural basis for the inhibition ofmore » hCE1 by the nanomolar-affinity dione benzil, which acts by forming both covalent and non-covalent complexes with the enzyme. Our results provide detailed insights into the catalytic and non-catalytic processing of small molecules by hCE1, and suggest that the efficacy of clinical drugs may be modulated by targeted hCE1 inhibitors.« less

  5. Structural insights into drug processing by human carboxylesterase 1: tamoxifen, mevastatin, and inhibition by benzil.

    PubMed

    Fleming, Christopher D; Bencharit, Sompop; Edwards, Carol C; Hyatt, Janice L; Tsurkan, Lyudmila; Bai, Feng; Fraga, Charles; Morton, Christopher L; Howard-Williams, Escher L; Potter, Philip M; Redinbo, Matthew R

    2005-09-09

    Human carboxylesterase 1 (hCE1) exhibits broad substrate specificity and is involved in xenobiotic processing and endobiotic metabolism. We present and analyze crystal structures of hCE1 in complexes with the cholesterol-lowering drug mevastatin, the breast cancer drug tamoxifen, the fatty acyl ethyl ester (FAEE) analogue ethyl acetate, and the novel hCE1 inhibitor benzil. We find that mevastatin does not appear to be a substrate for hCE1, and instead acts as a partially non-competitive inhibitor of the enzyme. Similarly, we show that tamoxifen is a low micromolar, partially non-competitive inhibitor of hCE1. Further, we describe the structural basis for the inhibition of hCE1 by the nanomolar-affinity dione benzil, which acts by forming both covalent and non-covalent complexes with the enzyme. Our results provide detailed insights into the catalytic and non-catalytic processing of small molecules by hCE1, and suggest that the efficacy of clinical drugs may be modulated by targeted hCE1 inhibitors.

  6. Steroid and xenobiotic receptor-mediated effects of bisphenol A on human osteoblasts.

    PubMed

    Miki, Yasuhiro; Hata, Shuko; Nagasaki, Shuji; Suzuki, Takashi; Ito, Kiyoshi; Kumamoto, Hiroyuki; Sasano, Hironobu

    2016-06-15

    Bisphenol A, one of the industrial chemicals used in plastics and in the coating of dishes and medical equipment, behaves as an endocrine disruptor in the human body. Bisphenol A can bind directly to several types of nuclear receptors, including steroid and xenobiotic receptor (SXR). SXR plays an important role in bone metabolism through the activation of osteoblasts in vitro, but SXR protein localization has not been reported in bone tissues. Additionally, it is not known whether bisphenol A acts on osteoblasts through SXR activation. Therefore, in this study, we first examined the immunolocalization of the SXR protein in human adult and fetal bone tissues. We then examined the effects of bisphenol A on human osteoblasts in vitro. SXR immunoreactivity was detected in osteoblasts, but not in osteoclasts, of both adult and fetal bone tissues. In fetal bone tissues, the mesenchymal cells or fetal connective tissue were also positive for SXR immunoreactivity. Expression of SXR target genes (tsukushi, matrilin-2, and CYP3A4) and SXR response element-luciferase activity were increased by bisphenol A treatment in normal osteoblasts transfected with SXR (hFOB/SXR) and in osteoblast-like cells (MG-63). Bisphenol A also stimulated cell proliferation and collagen accumulation in hFOB/SXR cells. These results suggest that, as in other tissues, SXR plays important roles in bone metabolism and fetal bone development and that bisphenol A may disturb bone homeostasis in both adult and fetus through SXR. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Harnessing Drug Resistance: Using ABC Transporter Proteins To Target Cancer Cells

    PubMed Central

    Leitner, Heather M.; Kachadourian, Remy; Day, Brian J.

    2007-01-01

    The ATP-binding cassette (ABC) class of proteins is one of the most functionally diverse transporter families found in biological systems. Although the abundance of ABC proteins varies between species, they are highly conserved in sequence and often demonstrate similar functions across prokaryotic and eukaryotic organisms. Beginning with a brief summary of the events leading to our present day knowledge of ABC transporters, the purpose of this review is to discuss the potential for utilizing ABC transporters as a means for cellular glutathione (GSH) modulation. GSH is one of the most abundant thiol antioxidants in cells. It is involved in cellular division, protein and DNA synthesis, maintenance of cellular redox status and xenobiotic metabolism. Cellular GSH levels are often altered in many disease states including cancer. Over the past two decades there has been considerable emphasis on methods to sensitize cancer cells to chemotherapeutics and ionization radiation therapy by GSH depletion. We contend that ABC transporters, particularly multi-drug resistant proteins (MRPs), may be used as therapeutic targets for applications aimed at modulation of GSH levels. This review will emphasize MRP-mediated modulation of intracellular GSH levels as a potential alternative and adjunctive approach for cancer therapy. PMID:17585883

  8. ABC transporters and cytochromes P450 in the human central nervous system: influence on brain pharmacokinetics and contribution to neurodegenerative disorders.

    PubMed

    Dutheil, Fabien; Jacob, Aude; Dauchy, Sandrine; Beaune, Philippe; Scherrmann, Jean-Michel; Declèves, Xavier; Loriot, Marie-Anne

    2010-10-01

    The identification of xenobiotic metabolizing enzymes (i.e., CYP) and transporters (i.e., ABC transporters) (XMET) in the human brain, including the BBB, raises the question whether these transporters and enzymes have specific functions in brain physiology, neuropharmacology and toxicology. Relevant literature was identified using PubMed search articles published up to March 2010. Search terms included 'ABC transporters and P450 or CYP', 'drug metabolism, effect and toxicity' and 'neurodegenerative disease (Alzheimer and Parkinson diseases)' restricted to the field of 'brain or human brain'. This review aims to provide a better understanding of XMET functions in the human brain and show their pharmacological importance for improving drug delivery and efficacy and also for managing their side effects. Finally, the impact of brain XMET activity during neurodegenerative processes is discussed, giving an opportunity to identify new markers of human brain diseases. During the last 2 decades, much evidence concerning the specific distribution patterns of XMET, their induction by xenobiotics and endobiotics and their genetic variations have made cerebral ABC transporters and CYP enzymes key elements in the way individual patients respond to centrally acting drugs.

  9. Altered carbohydrate, lipid, and xenobiotic metabolism by liver from rats flown on Cosmos 1887

    NASA Technical Reports Server (NTRS)

    Merrill, A. H. Jr; Hoel, M.; Wang, E.; Mullins, R. E.; Hargrove, J. L.; Jones, D. P.; Popova, I. A.; Merrill AH, J. r. (Principal Investigator)

    1990-01-01

    To determine the possible biochemical effects of prolonged weightlessness on liver function, samples of liver from rats that had flown aboard Cosmos 1887 were analyzed for protein, glycogen, and lipids as well as the activities of a number of key enzymes involved in metabolism of these compounds and xenobiotics. Among the parameters measured, the major differences were elevations in the glycogen content and hydroxymethylglutaryl-CoA (HMG-CoA) reductase activities for the rats flown on Cosmos 1887 and decreases in the amount of microsomal cytochrome P-450 and the activities of aniline hydroxylase and ethylmorphine N-demethylase, cytochrome P-450-dependent enzymes. These results support the earlier finding of differences in these parameters and suggest that altered hepatic function could be important during spaceflight and/or the postflight recovery period.

  10. Simultaneous detection of seventeen drugs of abuse and metabolites in hair using solid phase micro extraction (SPME) with GC/MS.

    PubMed

    Aleksa, Katarina; Walasek, Paula; Fulga, Netta; Kapur, Bhushan; Gareri, Joey; Koren, Gideon

    2012-05-10

    The analysis of pediatric and adult hair is a useful non-invasive biomarker to effectively detect long term exposure to various xenobiotics, specifically drugs of abuse such as cocaine, opiates and amphetamines. Very often individuals are using, or are exposed to multiple drugs simultaneously and therefore it is important to be able to detect them in the same analysis. We have developed a sensitive and specific solid phase micro extraction (SPME) coupled with gas chromatography mass spectrometry (GC/MS) to detect 17 different analytes in hair using a single extraction method. Five milligrams of hair is extracted overnight, subjected to solid phase extraction (SPE) and then to SPME-GC/MS. The aimed analytes include amphetamine, methamphetamine, MDA, MDMA, cocaine, benzoylecognine, norcocaine, cocaethylene, methadone, codeine, morphine, 6-AM, oxycodone, oxymorphone, hydrocodone, hydromorphone and meperidone. The following are the LOD of the various drugs: 0.2ng/mg hair for amphetamine, methamphetamine, MDA, MDMA, morphine, codeine, 6-AM, oxycodone, oxymorphone, hydromorphone, hydrocodone, meperidine and 0.13ng/mg hair for cocaine, benzoylecognine, cocaethylene, norcocaine and methadone. This GC/MS method is sensitive and specific to detect the presence of these 17 analytes in as little as 5mg of hair and is especially useful for newborn and child hair analysis where the amount of hair is often very limited. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  11. The Interactions of P-Glycoprotein with Antimalarial Drugs, Including Substrate Affinity, Inhibition and Regulation

    PubMed Central

    Senarathna, S M D K Ganga; Page-Sharp, Madhu; Crowe, Andrew

    2016-01-01

    The combination of passive drug permeability, affinity for uptake and efflux transporters as well as gastrointestinal metabolism defines net drug absorption. Efflux mechanisms are often overlooked when examining the absorption phase of drug bioavailability. Knowing the affinity of antimalarials for efflux transporters such as P-glycoprotein (P-gp) may assist in the determination of drug absorption and pharmacokinetic drug interactions during oral absorption in drug combination therapies. Concurrent administration of P-gp inhibitors and P-gp substrate drugs may also result in alterations in the bioavailability of some antimalarials. In-vitro Caco-2 cell monolayers were used here as a model for potential drug absorption related problems and P-gp mediated transport of drugs. Artemisone had the highest permeability at around 50 x 10−6 cm/sec, followed by amodiaquine around 20 x 10−6 cm/sec; both mefloquine and artesunate were around 10 x 10−6 cm/sec. Methylene blue was between 2 and 6 x 10−6 cm/sec depending on the direction of transport. This 3 fold difference was able to be halved by use of P-gp inhibition. MRP inhibition also assisted the consolidation of the methylene blue transport. Mefloquine was shown to be a P-gp inhibitor affecting our P-gp substrate, Rhodamine 123, although none of the other drugs impacted upon rhodamine123 transport rates. In conclusion, mefloquine is a P-gp inhibitor and methylene blue is a partial substrate; methylene blue may have increased absorption if co-administered with such P-gp inhibitors. An upregulation of P-gp was observed when artemisone and dihydroartemisinin were co-incubated with mefloquine and amodiaquine. PMID:27045516

  12. Underlying mechanism of drug-drug interaction between pioglitazone and gemfibrozil: Gemfibrozil acyl-glucuronide is a mechanism-based inhibitor of CYP2C8.

    PubMed

    Takagi, Motoi; Sakamoto, Masaya; Itoh, Tomoo; Fujiwara, Ryoichi

    2015-08-01

    While co-administered gemfibrozil can increase the area under the concentration/time curve (AUC) of pioglitazone more than 3-fold, the underlying mechanism of the drug-drug interaction between gemfibrozil and pioglitazone has not been fully understood. In the present study, gemfibrozil preincubation time-dependently inhibited the metabolism of pioglitazone in the cytochrome P450 (CYP)- and UDP-glucuronosyltransferase (UGT)-activated human liver microsomes. We estimated the kinact and K'app values, which are the maximum inactivation rate constant and the apparent dissociation constant, of gemfibrozil to be 0.071 min(-1) and 57.3 μM, respectively. In this study, the kobs, in vivo value was defined as a parameter that indicates the potency of the mechanism-based inhibitory effect at the blood drug concentration in vivo. The kobs, in vivo values of potent mechanism-based inhibitors, clarithromycin and erythromycin, were estimated to be 0.0096 min(-1) and 0.0051 min(-1), respectively. The kobs, in vivo value of gemfibrozil was 0.0060 min(-1), which was comparable to those of clarithromycin and erythromycin, suggesting that gemfibrozil could be a mechanism-based inhibitor as potent as clarithromycin and erythromycin in vivo. Copyright © 2015 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  13. 36 CFR 1212.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... drug-free workplace statement? 1212.205 Section 1212.205 Parks, Forests, and Public Property NATIONAL ARCHIVES AND RECORDS ADMINISTRATION GENERAL RULES GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE... my drug-free workplace statement? You must publish a statement that— (a) Tells your employees that...

  14. A structural examination and collision cross section database for over 500 metabolites and xenobiotics using drift tube ion mobility spectrometry† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc03464d

    PubMed Central

    Zheng, Xueyun; Aly, Noor A.; Zhou, Yuxuan; Dupuis, Kevin T.; Bilbao, Aivett; Paurus, Vanessa L.; Orton, Daniel J.; Wilson, Ryan; Payne, Samuel H.; Smith, Richard D.

    2017-01-01

    The confident identification of metabolites and xenobiotics in biological and environmental studies is an analytical challenge due to their immense dynamic range, vast chemical space and structural diversity. Ion mobility spectrometry (IMS) is widely used for small molecule analyses since it can separate isomeric species and be easily coupled with front end separations and mass spectrometry for multidimensional characterizations. However, to date IMS metabolomic and exposomic studies have been limited by an inadequate number of accurate collision cross section (CCS) values for small molecules, causing features to be detected but not confidently identified. In this work, we utilized drift tube IMS (DTIMS) to directly measure CCS values for over 500 small molecules including primary metabolites, secondary metabolites and xenobiotics. Since DTIMS measurements do not need calibrant ions or calibration like some other IMS techniques, they avoid calibration errors which can cause problems in distinguishing structurally similar molecules. All measurements were performed in triplicate in both positive and negative polarities with nitrogen gas and seven different electric fields, so that relative standard deviations (RSD) could be assessed for each molecule and structural differences studied. The primary metabolites analyzed to date have come from key metabolism pathways such as glycolysis, the pentose phosphate pathway and the tricarboxylic acid cycle, while the secondary metabolites consisted of classes such as terpenes and flavonoids, and the xenobiotics represented a range of molecules from antibiotics to polycyclic aromatic hydrocarbons. Different CCS trends were observed for several of the diverse small molecule classes and when urine features were matched to the database, the addition of the IMS dimension greatly reduced the possible number of candidate molecules. This CCS database and structural information are freely available for download at http

  15. Applicability of bioanalysis of multiple analytes in drug discovery and development: review of select case studies including assay development considerations.

    PubMed

    Srinivas, Nuggehally R

    2006-05-01

    The development of sound bioanalytical method(s) is of paramount importance during the process of drug discovery and development culminating in a marketing approval. Although the bioanalytical procedure(s) originally developed during the discovery stage may not necessarily be fit to support the drug development scenario, they may be suitably modified and validated, as deemed necessary. Several reviews have appeared over the years describing analytical approaches including various techniques, detection systems, automation tools that are available for an effective separation, enhanced selectivity and sensitivity for quantitation of many analytes. The intention of this review is to cover various key areas where analytical method development becomes necessary during different stages of drug discovery research and development process. The key areas covered in this article with relevant case studies include: (a) simultaneous assay for parent compound and metabolites that are purported to display pharmacological activity; (b) bioanalytical procedures for determination of multiple drugs in combating a disease; (c) analytical measurement of chirality aspects in the pharmacokinetics, metabolism and biotransformation investigations; (d) drug monitoring for therapeutic benefits and/or occupational hazard; (e) analysis of drugs from complex and/or less frequently used matrices; (f) analytical determination during in vitro experiments (metabolism and permeability related) and in situ intestinal perfusion experiments; (g) determination of a major metabolite as a surrogate for the parent molecule; (h) analytical approaches for universal determination of CYP450 probe substrates and metabolites; (i) analytical applicability to prodrug evaluations-simultaneous determination of prodrug, parent and metabolites; (j) quantitative determination of parent compound and/or phase II metabolite(s) via direct or indirect approaches; (k) applicability in analysis of multiple compounds in select

  16. Elevated levels of antibodies against xenobiotics in a subgroup of healthy subjects

    PubMed Central

    Vojdani, Aristo; Kharrazian, Datis; Mukherjee, Partha Sarathi

    2015-01-01

    In spite of numerous research efforts, the exact etiology of autoimmune diseases remains largely unknown. Genetics and environmental factors, including xenobiotics, are believed to be involved in the induction of autoimmune disease. Some environmental chemicals, acting as haptens, can bind to a high-molecular-weight carrier protein such as human serum albumin (HSA), causing the immune system to misidentify self-tissue as an invader and launch an immune response against it, leading to autoimmunity. This study aimed to examine the percentage of blood samples from healthy donors in which chemical agents mounted immune challenges and produced antibodies against HSA-bound chemicals. The levels of specific antibodies against 12 different chemicals bound to HSA were measured by ELISA in serum from 400 blood donors. We found that 10% (IgG) and 17% (IgM) of tested individuals showed significant antibody elevation against aflatoxin-HSA adduct. The percentage of elevation against the other 11 chemicals ranged from 8% to 22% (IgG) and 13% to 18% (IgM). Performance of serial dilution and inhibition of the chemical–antibody reaction by specific antigens but not by non-specific antigens were indicative of the specificity of these antibodies. Although we lack information about chemical exposure in the tested individuals, detection of antibodies against various protein adducts may indicate chronic exposure to these chemical haptens in about 20% of the tested individuals. Currently the pathological significance of these antibodies in human blood is still unclear, and this protein adduct formation could be one of the mechanisms by which environmental chemicals induce autoimmune reactivity in a significant percentage of the population. PMID:25042713

  17. Drug-resistant tuberculosis in subjects included in the Second National Survey on Antituberculosis Drug Resistance in Porto Alegre, Brazil*, **

    PubMed Central

    Micheletti, Vania Celina Dezoti; Moreira, José da Silva; Ribeiro, Marta Osório; Kritski, Afranio Lineu; Braga, José Ueleres

    2014-01-01

    OBJECTIVE: To describe the prevalence of multidrug-resistant tuberculosis (MDR-TB) among tuberculosis patients in a major Brazilian city, evaluated via the Second National Survey on Antituberculosis Drug Resistance, as well as the social, demographic, and clinical characteristics of those patients. METHODS: Clinical samples were collected from tuberculosis patients seen between 2006 to 2007 at three hospitals and five primary health care clinics participating in the survey in the city of Porto Alegre, Brazil. The samples were subjected to drug susceptibility testing. The species of mycobacteria was confirmed using biochemical methods. RESULTS: Of the 299 patients included, 221 (73.9%) were men and 77 (27.3%) had a history of tuberculosis. The mean age was 36 years. Of the 252 patients who underwent HIV testing, 66 (26.2%) tested positive. The prevalence of MDR-TB in the sample as a whole was 4.7% (95% CI: 2.3-7.1), whereas it was 2.2% (95% CI: 0.3-4.2) among the new cases of tuberculosis and 12.0% (95% CI: 4.5-19.5) among the patients with a history of tuberculosis treatment. The multivariate analysis showed that a history of tuberculosis and a longer time to diagnosis were both associated with MDR-TB. CONCLUSIONS: If our results are corroborated by other studies conducted in Brazil, a history of tuberculosis treatment and a longer time to diagnosis could be used as predictors of MDR-TB. PMID:24831400

  18. 41 CFR 105-74.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... my drug-free awareness program? 105-74.215 Section 105-74.215 Public Contracts and Property...

  19. 41 CFR 105-74.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... my drug-free awareness program? 105-74.215 Section 105-74.215 Public Contracts and Property...

  20. 41 CFR 105-74.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... my drug-free awareness program? 105-74.215 Section 105-74.215 Public Contracts and Property...

  1. 41 CFR 105-74.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... my drug-free awareness program? 105-74.215 Section 105-74.215 Public Contracts and Property...

  2. 41 CFR 105-74.215 - What must I include in my drug-free awareness program?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... employees about— (a) The dangers of drug abuse in the workplace; (b) Your policy of maintaining a drug-free... penalties that you may impose upon them for drug abuse violations occurring in the workplace. ... my drug-free awareness program? 105-74.215 Section 105-74.215 Public Contracts and Property...

  3. Phosphorylation of Isoflavones by Bacillus subtilis BCRC 80517 May Represent Xenobiotic Metabolism.

    PubMed

    Hsu, Chen; Wu, Bo-Yuan; Chang, Yu-Chuan; Chang, Chi-Fon; Chiou, Tai-Ying; Su, Nan-Wei

    2018-01-10

    The soy isoflavones daidzein (DAI) and genistein (GEN) have beneficial effects on human health. However, their oral bioavailability is hampered by their low aqueous solubility. Our previous study revealed two water-soluble phosphorylated conjugates of isoflavones, daidzein 7-O-phosphate and genistein 7-O-phosphate, generated via biotransformation by Bacillus subtilis BCRC80517 cultivated with isoflavones. In this study, two novel derivatives of isoflavones, daidzein 4'-O-phosphate and genistein 4'-O-phosphate, were identified by HPLC-ESI-MS/MS and 1 H, 13 C, and 31 P NMR, and their biotransformation roadmaps were proposed. Primarily, isoflavone glucosides were deglycosylated and then phosphorylated predominantly into 7-O-phosphate conjugates with traces of 4'-O-phosphate conjugates. Inevitably, trace quantities of glucosides were converted into 6″-O-succinyl glucosides. GEN was more efficiently phosphorylated than DAI. Nevertheless, the presence of GEN prolonged the time until the exponential phase of cell growth, whereas the other isoflavones showed little effect on cell growth. Our findings provide new insights into the novel microbial phosphorylation of isoflavones involved in xenobiotic metabolism.

  4. Role of Breast Cancer Resistance Protein (BCRP/ABCG2) in Cancer Drug Resistance

    PubMed Central

    Natarajan, Karthika; Xie, Yi; Baer, Maria R.; Ross, Douglas D.

    2012-01-01

    Since cloning of the ATP-binding cassette (ABC) family member breast cancer resistance protein (BCRP/ABCG2) and its characterization as a multidrug resistance efflux transporter in 1998, BCRP has been the subject of more than two thousand scholarly articles. In normal tissues, BCRP functions as a defense mechanism against toxins and xenobiotics, with expression in the gut, bile canaliculi, placenta, blood-testis and blood-brain barriers facilitating excretion and limiting absorption of potentially toxic substrate molecules, including many cancer chemotherapeutic drugs. BCRP also plays a key role in heme and folate homeostasis, which may help normal cells survive under conditions of hypoxia. BCRP expression appears to be a characteristic of certain normal tissue stem cells termed “side population cells,” which are identified on flow cytometric analysis by their ability to exclude Hoechst 33342, a BCRP substrate fluorescent dye. Hence, BCRP expression may contribute to the natural resistance and longevity of these normal stem cells. Malignant tissues can exploit the properties of BCRP to survive hypoxia and to evade exposure to chemotherapeutic drugs. Evidence is mounting that many cancers display subpopulations of stem cells that are responsible for tumor self-renewal. Such stem cells frequently manifest the “side population” phenotype characterized by expression of BCRP and other ABC transporters. Along with other factors, these transporters may contribute to the inherent resistance of these neoplasms and their failure to be cured. PMID:22248732

  5. 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

  6. The association of antidepressant drug usage with cognitive impairment or dementia, including Alzheimer disease: A systematic review and meta‐analysis

    PubMed Central

    Moraros, John; Nwankwo, Chijioke; Patten, Scott B.

    2016-01-01

    1 Objective To determine if antidepressant drug usage is associated with cognitive impairment or dementia, including Alzheimer disease (AD). 2 Method We conducted a systematic search of Medline, PubMed, PsycINFO, Web of Science, Embase, CINAHL, and the Cochrane Library. An initial screen by abstracts and titles was performed, and relevant full articles were then reviewed and assessed for their methodologic quality. Crude effect estimates were extracted from the included articles and a pooled estimate was obtained using a random effects model. 3 Results Five articles were selected from an initial pool of 4,123 articles. Use of antidepressant drugs was associated with a significant twofold increase in the odds of some form of cognitive impairment or dementia (OR = 2.17). Age was identified as a likely modifier of the association between antidepressant use and some form of cognitive impairment or AD/dementia. Studies that included participants with an average age equal to or greater than 65 years showed an increased odds of some form of cognitive impairment with antidepressant drug usage (OR = 1.65), whereas those with participants less than age 65 revealed an even stronger association (OR = 3.25). 4 Conclusions Antidepressant drug usage is associated with AD/dementia and this is particularly evident if usage begins before age 65. This association may arise due to confounding by depression or depression severity. However, biological mechanisms potentially linking antidepressant exposure to dementia have been described, so an etiological effect of antidepressants is possible. With this confirmation that an association exists, clarification of underlying etiologic pathways requires urgent attention. PMID:28029715

  7. Herbal medicines in Brazil: pharmacokinetic profile and potential herb-drug interactions

    PubMed Central

    Mazzari, Andre L. D. A.; Prieto, Jose M.

    2014-01-01

    A plethora of active compounds found in herbal medicines can serve as substrate for enzymes involved in the metabolism of xenobiotics. When a medicinal plant is co-administered with a conventional drug and little or no information is known about the pharmacokinetics of the plant metabolites, there is an increased risk of potential herb-drug interactions. Moreover, genetic polymorphisms in a population may act to predispose individuals to adverse reactions. The use of herbal medicines is rapidly increasing in many countries, particularly Brazil where the vast biodiversity is a potential source of new and more affordable treatments for numerous conditions. Accordingly, the Brazilian Unified Public Health System (SUS) produced a list of 71 plant species of interest, which could be made available to the population in the near future. Physicians at SUS prescribe a number of essential drugs and should herbal medicines be added to this system the chance of herb-drug interactions further increases. A review of the effects of these medicinal plants on Phase 1 and Phase 2 metabolic mechanisms and the transporter P-glycoprotein was conducted. The results have shown that approximately half of these medicinal plants lack any pharmacokinetic data. Moreover, most of the studies carried out are in vitro. Only a few reports on herb-drug interactions with essential drugs prescribed by SUS were found, suggesting that very little attention is being given to the safety of herbal medicines. Here we have taken this information to discuss the potential interactions between herbal medicines and essential drugs prescribed to Brazilian patients whilst taking into account the most common polymorphisms present in the Brazilian population. A number of theoretical interactions are pinpointed but more pharmacokinetic studies and pharmacovigilance data are needed to ascertain their clinical significance. PMID:25071580

  8. Isolation and identification of flavonoids, including flavone rotamers, from the herbal drug 'Crataegi folium cum flore' (hawthorn).

    PubMed

    Rayyan, S; Fossen, T; Solheim Nateland, H; Andersen, O M

    2005-01-01

    Twelve flavonoids, including seven flavones, four flavonols and one flavanone, were isolated from methanolic extract of the herbal drug 'Crataegi folium cum flore' (hawthorn leaves and flowers) by a combination of CC (over Amberlite XAD-7 and Sephadex LH-20) and preparative HPLC. Their structures, including that of the novel flavonol 8-methoxykaempferol 3-O-(6"-malonyl-beta-glucopyranoside), were elucidated by homo- and heteronuclear NMR and electrospray/MS. The 1H- and 13C-NMR of all compounds, including rotameric pairs of five flavone C-glycosides, were assigned. The presence and relative proportion of each rotamer was shown by various NMR experiments, including two-dimensional nuclear Overhauser and exchange spectroscopy, to depend on solvent, linkage position and structure of the C-glycosyl substituent.

  9. The association of antidepressant drug usage with cognitive impairment or dementia, including Alzheimer disease: A systematic review and meta-analysis.

    PubMed

    Moraros, John; Nwankwo, Chijioke; Patten, Scott B; Mousseau, Darrell D

    2017-03-01

    To determine if antidepressant drug usage is associated with cognitive impairment or dementia, including Alzheimer disease (AD). We conducted a systematic search of Medline, PubMed, PsycINFO, Web of Science, Embase, CINAHL, and the Cochrane Library. An initial screen by abstracts and titles was performed, and relevant full articles were then reviewed and assessed for their methodologic quality. Crude effect estimates were extracted from the included articles and a pooled estimate was obtained using a random effects model. Five articles were selected from an initial pool of 4,123 articles. Use of antidepressant drugs was associated with a significant twofold increase in the odds of some form of cognitive impairment or dementia (OR = 2.17). Age was identified as a likely modifier of the association between antidepressant use and some form of cognitive impairment or AD/dementia. Studies that included participants with an average age equal to or greater than 65 years showed an increased odds of some form of cognitive impairment with antidepressant drug usage (OR = 1.65), whereas those with participants less than age 65 revealed an even stronger association (OR = 3.25). Antidepressant drug usage is associated with AD/dementia and this is particularly evident if usage begins before age 65. This association may arise due to confounding by depression or depression severity. However, biological mechanisms potentially linking antidepressant exposure to dementia have been described, so an etiological effect of antidepressants is possible. With this confirmation that an association exists, clarification of underlying etiologic pathways requires urgent attention. © 2016 The Authors. Depression and Anxiety published by Wiley Periodicals, Inc.

  10. Functional expression and regulation of drug transporters in monolayer- and sandwich-cultured mouse hepatocytes.

    PubMed

    Noel, Gregory; Le Vee, Marc; Moreau, Amélie; Stieger, Bruno; Parmentier, Yannick; Fardel, Olivier

    2013-04-11

    Primary hepatocyte cultures are now considered as convenient models for in vitro analyzing liver drug transport. However, if primary human and rat hepatocytes have been well-characterized with respect to drug transporter expression and regulation, much less is known for primary mouse hepatocytes. The present study was therefore designed to gain insights about this point. The profile of sinusoidal and canalicular drug transporter mRNA expression in short time (4h)-cultured mouse hepatocytes was found to be highly correlated with that of freshly isolated hepatocytes; by contrast, those of counterparts cultured for a longer time (until 4 days) either in monolayer configurations on plastic or collagen or in sandwich configuration with matrigel were profoundly altered: uptake drug transporters such as Oct1, Oatps and Oat2 were thus down-regulated, whereas most of efflux transporters such as Mdr1a/b, Mrp3, Mrp4 and Bcrp were induced. Moreover, short time-cultured hepatocytes exhibited the highest levels of sinusoidal influx transporter activities. Transporter-mediated drug secretion into canalicular networks was however only observed in sandwich-cultured hepatocytes. Mouse hepatocytes cultured either in monolayer or sandwich configurations were finally shown to exhibit up-regulation of referent transporters in response to exposure to prototypical activators of the drug sensing receptors pregnane X receptor, aryl hydrocarbon receptor or constitutive androstane receptor. Taken together, these data demonstrate the feasibility of using primary mouse hepatocytes for investigating potential interactions of xenobiotics with hepatic transporter activity or regulation, provided that adequate culture conditions are retained. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. 38 CFR 48.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... drug-free workplace statement? 48.205 Section 48.205 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS (CONTINUED) GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL... workplace statement? You must publish a statement that— (a) Tells your employees that the unlawful...

  12. The effects of emulsifying agents on disposition of lipid-soluble drugs included in fat emulsion.

    PubMed

    Suzuki, Yasuyuki; Masumitsu, Yasushi; Okudaira, Kazuho; Hayashi, Masahiro

    2004-02-01

    The uses for drug delivery systems of two soybean oil fat emulsions prepared with an emulsifying agent, phosphatidyl choline (PC) or Pluronic F-127 (PLU), were examined comparatively in vivo and in vitro. In the presence of lipoprotein lipase (LPL) in vitro, the mean particle size of the PLU emulsion changed less than that of the PC emulsion. The production of non-esterified fatty acid (NEFA) from the PLU emulsion in the presence of LPL was smaller than that from the PC emulsion. These in vitro results indicate that the PLU emulsion is more stable than the PC emulsion. Plasma NEFA concentration following intravenous administration of the emulsions decreased with time for the PC emulsion, but was kept lower and constant for the PLU emulsion, supporting the in vitro stability data. The order of plasma cyclosporine A (CsA) concentration following intravenous administration in the above two emulsions and the mixed solution of polyethylene glycol 400 (PEG) and dimethylamide (DMA) in rats was PLU emulsion>PC emulsion>PEG/DMA solution. The plasma concentration was maintained higher and tissue distribution lower for the PLU emulsion than for other formulations. The uptake of oil violet (OV) into the rat parenchymal cells from the PLU emulsion was approximately half that from the PC emulsion, but the uptake into the Kupffer cells was almost equal in both emulsions. In conclusion, these emulsifying agents can control plasma elimination and tissue distribution of lipophilic drugs included in the emulsion. The use of the emulsion formulation makes it possible to avoid side effects through the reduction of drug uptake into non-targeted tissues.

  13. Nrf2 the rescue: effects of the antioxidative/electrophilic response on the liver.

    PubMed

    Klaassen, Curtis D; Reisman, Scott A

    2010-04-01

    Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that positively regulates the basal and inducible expression of a large battery of cytoprotective genes. These gene products include proteins that catalyze reduction reactions (NAD(P)H:quinone oxidoreductase 1, Nqo1), conjugation reactions (glutathione-S-transferases, Gsts and UDP-glucuronosyltransferases, Ugts), as well as the efflux of potentially toxic xenobiotics and xenobiotic conjugates (multidrug resistance-associated proteins, Mrps). The significance of Nrf2 in the liver has been established, as livers of Nrf2-null mice are more susceptible to various oxidative/electrophilic stress-induced pathologies than wild-type mice. In contrast, both pharmacological and genetic models of hepatic Nrf2 activation are protective against oxidative/electrophilic stress. Furthermore, because certain Nrf2-target genes in the liver could affect the distribution, metabolism, and excretion of xenobiotics, the effects of Nrf2 on the kinetics of drugs and other xenobiotics should also be considered, with a special emphasis on metabolism and excretion. Therefore, this review highlights the research that has contributed to the understanding of the importance of Nrf2 in toxicodynamics and toxicokinetics, especially that which pertains to the liver. 2010 Elsevier Inc. All rights reserved.

  14. Novel Yeast-based Strategy Unveils Antagonist Binding Regions on the Nuclear Xenobiotic Receptor PXR*

    PubMed Central

    Li, Hao; Redinbo, Matthew R.; Venkatesh, Madhukumar; Ekins, Sean; Chaudhry, Anik; Bloch, Nicolin; Negassa, Abdissa; Mukherjee, Paromita; Kalpana, Ganjam; Mani, Sridhar

    2013-01-01

    The pregnane X receptor (PXR) is a master regulator of xenobiotic metabolism, and its activity is critical toward understanding the pathophysiology of several diseases, including inflammation, cancer, and steatosis. Previous studies have demonstrated that ketoconazole binds to ligand-activated PXR and antagonizes receptor control of gene expression. Structure-function as well as computational docking analysis suggested a putative binding region containing critical charge clamp residues Gln-272, and Phe-264 on the AF-2 surface of PXR. To define the antagonist binding surface(s) of PXR, we developed a novel assay to identify key amino acid residues on PXR based on a yeast two-hybrid screen that examined mutant forms of PXR. This screen identified multiple “gain-of-function” mutants that were “resistant” to the PXR antagonist effects of ketoconazole. We then compared our screen results identifying key PXR residues to those predicted by computational methods. Of 15 potential or putative binding residues based on docking, we identified three residues in the yeast screen that were then systematically verified to functionally interact with ketoconazole using mammalian assays. Among the residues confirmed by our study was Ser-208, which is on the opposite side of the protein from the AF-2 region critical for receptor regulation. The identification of new locations for antagonist binding on the surface or buried in PXR indicates novel aspects to the mechanism of receptor antagonism. These results significantly expand our understanding of antagonist binding sites on the surface of PXR and suggest new avenues to regulate this receptor for clinical applications. PMID:23525103

  15. 2 CFR 182.205 - What must I include in my drug-free workplace statement?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... workplace statement? 182.205 Section 182.205 Grants and Agreements OFFICE OF MANAGEMENT AND BUDGET GOVERNMENTWIDE GUIDANCE FOR GRANTS AND AGREEMENTS Reserved GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE... drug-free workplace statement? You must publish a statement that— (a) Tells your employees that the...

  16. 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...

  17. Shotgun ecotoxicoproteomics of Daphnia pulex: biochemical effects of the anticancer drug tamoxifen.

    PubMed

    Borgatta, Myriam; Hernandez, Céline; Decosterd, Laurent Arthur; Chèvre, Nathalie; Waridel, Patrice

    2015-01-02

    Among pollutants released into the environment by human activities, residues of pharmaceuticals are an increasing matter of concern because of their potential impact on ecosystems. The aim of this study was to analyze differences of protein expression resulting from acute (2 days) and middle-term (7 days) exposure of aquatic microcrustacean Daphnia pulex to the anticancer drug tamoxifen. Using a liquid chromatography-mass spectrometry shotgun approach, about 4000 proteins could be identified, providing the largest proteomics data set of D. pulex published up to now. Considering both time points and tested concentrations, 189 proteins showed a significant fold change. The identity of regulated proteins suggested a decrease in translation, an increase in protein degradation and changes in carbohydrate and lipid metabolism as the major effects of the drug. Besides these impacted processes, which reflect a general stress response of the organism, some other regulated proteins play a role in Daphnia reproduction. These latter results are in accordance with our previous observations of the impact of tamoxifen on D. pulex reproduction and illustrate the potential of ecotoxicoproteomics to unravel links between xenobiotic effects at the biochemical and organismal levels. Data are available via ProteomeXchange with identifier PXD001257.

  18. 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.

  19. 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. Copyright © 2016 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  20. Genome-Wide Discovery of Drug-Dependent Human Liver Regulatory Elements

    PubMed Central

    Morrissey, Kari M.; Luizon, Marcelo R.; Hoffmann, Thomas J.; Sun, Xuefeng; Jones, Stacy L.; Force Aldred, Shelley; Ramamoorthy, Anuradha; Desta, Zeruesenay; Liu, Yunlong; Skaar, Todd C.; Trinklein, Nathan D.; Giacomini, Kathleen M.; Ahituv, Nadav

    2014-01-01

    Inter-individual variation in gene regulatory elements is hypothesized to play a causative role in adverse drug reactions and reduced drug activity. However, relatively little is known about the location and function of drug-dependent elements. To uncover drug-associated elements in a genome-wide manner, we performed RNA-seq and ChIP-seq using antibodies against the pregnane X receptor (PXR) and three active regulatory marks (p300, H3K4me1, H3K27ac) on primary human hepatocytes treated with rifampin or vehicle control. Rifampin and PXR were chosen since they are part of the CYP3A4 pathway, which is known to account for the metabolism of more than 50% of all prescribed drugs. We selected 227 proximal promoters for genes with rifampin-dependent expression or nearby PXR/p300 occupancy sites and assayed their ability to induce luciferase in rifampin-treated HepG2 cells, finding only 10 (4.4%) that exhibited drug-dependent activity. As this result suggested a role for distal enhancer modules, we searched more broadly to identify 1,297 genomic regions bearing a conditional PXR occupancy as well as all three active regulatory marks. These regions are enriched near genes that function in the metabolism of xenobiotics, specifically members of the cytochrome P450 family. We performed enhancer assays in rifampin-treated HepG2 cells for 42 of these sequences as well as 7 sequences that overlap linkage-disequilibrium blocks defined by lead SNPs from pharmacogenomic GWAS studies, revealing 15/42 and 4/7 to be functional enhancers, respectively. A common African haplotype in one of these enhancers in the GSTA locus was found to exhibit potential rifampin hypersensitivity. Combined, our results further suggest that enhancers are the predominant targets of rifampin-induced PXR activation, provide a genome-wide catalog of PXR targets and serve as a model for the identification of drug-responsive regulatory elements. PMID:25275310

  1. Despite 2007 law requiring FDA hotline to be included in print drug ads, reporting of adverse events by consumers still low.

    PubMed

    Du, Dongyi; Goldsmith, John; Aikin, Kathryn J; Encinosa, William E; Nardinelli, Clark

    2012-05-01

    In 2007 the federal government began requiring drug makers to include in their print direct-to-consumer advertisements information for consumers on how to contact the Food and Drug Administration directly, either by phone or through the agency's website, to report any adverse events that they experienced after taking a prescription drug. Adverse events can range from minor skin problems like itching to serious injuries or illness that result in hospitalization, permanent disability, or even death. Even so, current rates of adverse event reporting are low. We studied adverse event reports about 123 drugs that came from patients before and after the enactment of the print advertising requirement and estimated that requirement's impact with model simulations. We found that if monthly spending on print direct-to-consumer advertising increased from zero to $7.7 million per drug, the presence of the Food and Drug Administration contact information tripled the increase in patient-reported adverse events, compared to what would have happened in the absence of the law. However, the absolute monthly increase was fewer than 0.24 reports per drug, suggesting that the public health impact of the increase was small and that the adverse event reporting rate would still be low. The study results suggest that additional measures, such as more publicity about the Adverse Event Reporting System or more consumer education, should be considered to promote patient reporting of adverse events.

  2. Assessment of mitochondrial dysfunction-related, drug-induced hepatotoxicity in primary rat hepatocytes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Cong; Sekine, Shuichi, E-mail: ssekine@facult

    Evidence that mitochondrial dysfunction plays a central role in drug-induced liver injury is rapidly accumulating. In contrast to physiological conditions, in which almost all adenosine triphosphate (ATP) in hepatocytes is generated in mitochondria via aerobic respiration, the high glucose content and limited oxygen supply of conventional culture systems force primary hepatocytes to generate most ATP via cytosolic glycolysis. Thus, such anaerobically poised cells are resistant to xenobiotics that impair mitochondrial function, and are not suitable to identify drugs with mitochondrial liabilities. In this study, primary rat hepatocytes were cultured in galactose-based medium, instead of the conventional glucose-based medium, and inmore » hyperoxia to improve the reliance of energy generation on aerobic respiration. Activation of mitochondria was verified by diminished cellular lactate release and increased oxygen consumption. These conditions improved sensitivity to the mitochondrial complex I inhibitor rotenone. Since oxidative stress is also a general cause of mitochondrial impairment, cells were exposed to test compounds in the presence of transferrin to increase the generation of reactive oxygen species via increased uptake of iron. Finally, 14 compounds with reported mitochondrial liabilities were tested to validate this new drug-induced mitochondrial toxicity assay. Overall, the culture of primary rat hepatocytes in galactose, hyperoxia and transferrin is a useful model for the identification of mitochondrial dysfunction-related drug-induced hepatotoxicity. - Highlights: • Drug-induced mitochondrial toxicity was evaluated using primary rat hepatocytes. • Galactose and hyperoxia could activate OXPHOS in primary rat hepatocytes. • Cells with enhanced OXPHOS exhibit improved sensitivity to mitochondrial toxins. • Transferrin potentiate mitochondrial toxicity via increased ROS production.« less

  3. Bitter melon extracts enhance the activity of chemotherapeutic agents through the modulation of multiple drug resistance.

    PubMed

    Kwatra, Deep; Venugopal, Anand; Standing, David; Ponnurangam, Sivapriya; Dhar, Animesh; Mitra, Ashim; Anant, Shrikant

    2013-12-01

    Recently, we demonstrated that extracts of bitter melon (BME) can be used as a preventive/therapeutic agent in colon cancers. Here, we determined BME effects on anticancer activity and bioavailability of doxorubicin (DOX) in colon cancer cells. BME enhanced the effect of DOX on cell proliferation and sensitized the cells toward DOX upon pretreatment. Furthermore, there was both increased drug uptake and reduced drug efflux. We also observed a reduction in the expression of multidrug resistance conferring proteins (MDRCP) P-glycoprotein, MRP-2, and BCRP. Further BME suppressed DOX efflux in MDCK cells overexpressing the three efflux proteins individually, suggesting that BME is a potent inhibitor of MDR function. Next, we determined the effect of BME on PXR, a xenobiotic sensing nuclear receptor and a transcription factor that controls the expression of the three MDR genes. BME suppressed PXR promoter activity thereby suppressing its expression. Finally, we determined the effect of AMPK pathway on drug efflux because we have previously demonstrated that BME affects the pathway. However, inhibiting AMPK did not affect drug resistance, suggesting that BME may use different pathways for the anticancer and MDR modulating activities. Together, these results suggest that BME can enhance the bioavailability and efficacy of conventional chemotherapy. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  4. Human cytosolic glutathione-S-transferases: quantitative analysis of expression, comparative analysis of structures and inhibition strategies of isozymes involved in drug resistance.

    PubMed

    Mohana, Krishnamoorthy; Achary, Anant

    2017-08-01

    Glutathione-S-transferase (GST) inhibition is a strategy to overcome drug resistance. Several isoforms of human GSTs are present and they are expressed in almost all the organs. Specific expression levels of GSTs in various organs are collected from the human transcriptome data and analysis of the organ-specific expression of GST isoforms is carried out. The variations in the level of expressions of GST isoforms are statistically significant. The GST expression differs in diseased conditions as reported by many investigators and some of the isoforms of GSTs are disease markers or drug targets. Structure analysis of various isoforms is carried out and literature mining has been performed to identify the differences in the active sites of the GSTs. The xenobiotic binding H site is classified into H1, H2, and H3 and the differences in the amino acid composition, the hydrophobicity and other structural features of H site of GSTs are discussed. The existing inhibition strategies are compared. The advent of rational drug design, mechanism-based inhibition strategies, availability of high-throughput screening, target specific, and selective inhibition of GST isoforms involved in drug resistance could be achieved for the reversal of drug resistance and aid in the treatment of diseases.

  5. Extending the DIDEO ontology to include entities from the natural product drug interaction domain of discourse.

    PubMed

    Judkins, John; Tay-Sontheimer, Jessica; Boyce, Richard D; Brochhausen, Mathias

    2018-05-09

    Prompted by the frequency of concomitant use of prescription drugs with natural products, and the lack of knowledge regarding the impact of pharmacokinetic-based natural product-drug interactions (PK-NPDIs), the United States National Center for Complementary and Integrative Health has established a center of excellence for PK-NPDI. The Center is creating a public database to help researchers (primarly pharmacologists and medicinal chemists) to share and access data, results, and methods from PK-NPDI studies. In order to represent the semantics of the data and foster interoperability, we are extending the Drug-Drug Interaction and Evidence Ontology (DIDEO) to include definitions for terms used by the data repository. This is feasible due to a number of similarities between pharmacokinetic drug-drug interactions and PK-NPDIs. To achieve this, we set up an iterative domain analysis in the following steps. In Step 1 PK-NPDI domain experts produce a list of terms and definitions based on data from PK-NPDI studies, in Step 2 an ontology expert creates ontologically appropriate classes and definitions from the list along with class axioms, in Step 3 there is an iterative editing process during which the domain experts and the ontology experts review, assess, and amend class labels and definitions and in Step 4 the ontology expert implements the new classes in the DIDEO development branch. This workflow often results in different labels and definitions for the new classes in DIDEO than the domain experts initially provided; the latter are preserved in DIDEO as separate annotations. Step 1 resulted in a list of 344 terms. During Step 2 we found that 9 of these terms already existed in DIDEO, and 6 existed in other OBO Foundry ontologies. These 6 were imported into DIDEO; additional terms from multiple OBO Foundry ontologies were also imported, either to serve as superclasses for new terms in the initial list or to build axioms for these terms. At the time of writing, 7

  6. Xenobiotic interaction with and alteration of channel catfish estrogen receptor.

    PubMed

    Nimrod, A C; Benson, W H

    1997-12-01

    In teleostean in vivo studies, the vitellogenin response to environmental estrogens is not completely predicted by mammalian literature. One possible explanation for differences is heterogeneity of the estrogen receptor (ER) structure between species. Therefore, ER from channel catfish (Ictalurus punctatus) hepatic tissue was characterized by binding affinity for several compounds. Affinity was indirectly measured as potency of the chemical for inhibiting binding of radiolabeled estradiol (E2) to specific binding sites. The order of potency among therapeutic chemicals was ethinylestradiol > unlabeled E2 = diethylstilbestrol > mestranol > tamoxifen > testosterone. Unlabeled E2 had an IC50 of 2.2 nM. Several environmentally relevant chemicals were evaluated in a similar manner and the order of potency established was the o-demethylated metabolite of methoxychlor (MXC) > nonylphenol (NP) > chlordecone > MXC > o,p'-DDT > o,p'-DDE > beta-hexachlorocyclohexane. Demethylated MXC had an IC50 1000-fold greater than that of E2. Of the most potent inhibitors, NP appeared to be a competitive inhibitor for the same binding site as E2, while o-demethylated MXC had a more complex interaction with the receptor protein. ER from nonvitellogenic females was determined to have a Kd value of 1.0 to 1.3 nM. Because E2 has been reported to up-regulate teleostean ER, the hepatic ER population following in vivo xenobiotic exposure was assessed. NP significantly increased ER per milligram hepatic protein almost to the same extent as E2, but did not increase Kd to the same extent as E2.

  7. Biotransformation and induction: implications for toxicity, bioaccumulation and monitoring of environmental xenobiotics in fish.

    PubMed Central

    Kleinow, K M; Melancon, M J; Lech, J J

    1987-01-01

    Biotransformation of xenobiotics in fish occurs by many of the same reactions as in mammals. These reactions have been shown to affect the bioaccumulation, persistence, residue dynamics, and toxicity of select chemicals in fish. P-450-dependent monooxygenase activity of fish can be induced by polycyclic aromatic hydrocarbons, but phenobarbital-type agents induce poorly, if at all. Fish monooxygenase activity exhibits ideal temperature compensation and sex-related variation. Induction of monooxygenase activity by polycyclic aromatic hydrocarbons can result in qualitative as well as quantitative changes in the metabolic profile of a chemical. Induction can also alter toxicity. In addition, multiple P-450 isozymes have been described for several fish species. The biotransformation products of certain chemicals have been related to specific P-450 isozymes, and the formation of these products can be influenced by induction. Exposure of fish to low levels of certain environmental contaminants has resulted in induction of specific monooxygenase activities and monitoring of such activities has been suggested as a means of identifying areas of pollutant exposure in the wild. PMID:3297653

  8. Impact of environmental exposures on ovarian function and role of xenobiotic metabolism during ovotoxicity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bhattacharya, Poulomi; Keating, Aileen F., E-mail: akeating@iastate.edu

    2012-06-15

    The mammalian ovary is a heterogeneous organ and contains oocyte-containing follicles at varying stages of development. The most immature follicular stage, the primordial follicle, comprises the ovarian reserve and is a finite number, defined at the time of birth. Depletion of all follicles within the ovary leads to reproductive senescence, known as menopause. A number of chemical classes can destroy follicles, thus hastening entry into the menopausal state. The ovarian response to chemical exposure can determine the extent of ovotoxicity that occurs. Enzymes capable of bioactivating as well as detoxifying xenobiotics are expressed in the ovary and their impact onmore » ovotoxicity has been partially characterized for trichloroethylene, 7,12-dimethylbenz[a]anthracene, and 4-vinylcyclohexene. This review will discuss those studies, as well as illustrate where knowledge gaps remain for chemicals that have also been established as ovotoxicants. -- Highlights: ► Summary of ovotoxicant action during ovotoxicity. ► Discussion of impact of biotransformation on chemical toxicity. ► Identification of knowledge gaps in chemical metabolism.« less

  9. A sampling scheme to assess persistence and transport characteristics of xenobiotics within an urban river section

    NASA Astrophysics Data System (ADS)

    Schwientek, Marc; Guillet, Gaelle; Kuch, Bertram; Rügner, Hermann; Grathwohl, Peter

    2014-05-01

    Xenobiotic contaminants such as pharmaceuticals or personal care products typically are continuously introduced into the receiving water bodies via wastewater treatment plant (WWTP) outfalls and, episodically, via combined sewer overflows in the case of precipitation events. Little is known about how these chemicals behave in the environment and how they affect ecosystems and human health. Examples of traditional persistent organic pollutants reveal, that they may still be present in the environment even decades after they have been released. In this study a sampling strategy was developed which gives valuable insights into the environmental behaviour of xenobiotic chemicals. The method is based on the Lagrangian sampling scheme by which a parcel of water is sampled repeatedly as it moves downstream while chemical, physical, and hydrologic processes altering the characteristics of the water mass can be investigated. The Steinlach is a tributary of the River Neckar in Southwest Germany with a catchment area of 140 km². It receives the effluents of a WWTP with 99,000 inhabitant equivalents 4 km upstream of its mouth. The varying flow rate of effluents induces temporal patterns of electrical conductivity in the river water which enable to track parcels of water along the subsequent urban river section. These parcels of water were sampled a) close to the outlet of the WWTP and b) 4 km downstream at the confluence with the Neckar. Sampling was repeated at a 15 min interval over a complete diurnal cycle and 2 h composite samples were prepared. A model-based analysis demonstrated, on the one hand, that substances behaved reactively to a varying extend along the studied river section. On the other hand, it revealed that the observed degradation rates are likely dependent on the time of day. Some chemicals were degraded mainly during daytime (e.g. the disinfectant Triclosan or the phosphorous flame retardant TDCP), others as well during nighttime (e.g. the musk fragrance

  10. Human induced pluripotent stem cell line with cytochrome P450 enzyme polymorphism (CYP2C19*2/CYP3A5*3C) generated from lymphoblastoid cells.

    PubMed

    Lee, Jaehun; Woo, Dong-Hun; Park, Han-Jin; Park, Kijung; Ko, Duck Sung; Kim, Jong-Hoon

    2018-03-01

    Cytochrome P450 (CYP) comprises a superfamily of monooxygenase responsible for the metabolism of xenobiotics and approximately 75% of drugs in use today. Thus, genetic polymorphisms in CYP genes contribute to interindividual differences in hepatic metabolism of drugs, affecting on individual drug efficacy and may cause adverse effects. Here, we generated a human induced pluripotent stem cell (hiPSC) line with pharmacologically important traits (CYP2C19*2/CYP3A5*3C), which are highly polymorphic in Asian from lymphoblastoid cells. This hiPSC line could be a valuable source for predicting individual drug responses in the drug screening process that uses hiPSC-derived somatic cells, including hepatocytes. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  11. NEW METHODS FOR THE ASSESSMENT OF IMMUNOTOXICITY OF CHEMICAL SUBSTANCES

    EPA Science Inventory

    The immune system is a target of toxic insult following subchronic or chronic exposure to environmental chemicals, therapeutic drugs or abused drugs. nteraction of xenobiotics with the immune system may result in undesirable effects of three principal types; (a) those manifested ...

  12. Xenobiotic/medium chain fatty acid: CoA ligase - a critical review on its role in fatty acid metabolism and the detoxification of benzoic acid and aspirin.

    PubMed

    van der Sluis, Rencia; Erasmus, Elardus

    2016-10-01

    Activation of fatty acids by the acyl-CoA synthetases (ACSs) is the vital first step in fatty acid metabolism. The enzymatic and physiological characterization of the human xenobiotic/medium chain fatty acid: CoA ligases (ACSMs) has been severely neglected even though xenobiotics, such as benzoate and salicylate, are detoxified through this pathway. This review will focus on the nomenclature and substrate specificity of the human ACSM ligases; the biochemical and enzymatic characterization of ACSM1 and ACSM2B; the high sequence homology of the ACSM2 genes (ACSM2A and ACSM2B) as well as what is currently known regarding disease association studies. Several discrepancies exist in the current literature that should be taken note of. For example, the single nucleotide polymorphisms (SNPs) reported to be associated with aspirin metabolism and multiple risk factors of metabolic syndrome are incorrect. Kinetic data on the substrate specificity of the human ACSM ligases are non-existent and currently no data exist on the influence of SNPs on the enzyme activity of these ligases. One of the biggest obstacles currently in the field is that glycine conjugation is continuously studied as a one-step process, which means that key regulatory factors of the two individual steps remain unknown.

  13. Multifunctional High Drug Loading Nanocarriers for Cancer Drug Delivery

    NASA Astrophysics Data System (ADS)

    Jin, Erlei

    2011-12-01

    Most anticancer drugs have poor water-solubility, rapid blood clearance, low tumor-selectivity and severe systemic toxicity to healthy tissues. Thus, polymeric nanocarriers have been widely explored for anticancer drugs to solve these problems. However, polymer nanocarriers developed to date still suffer drawbacks including low drug loading contents, premature drug release, slow cellular internalization, slow intracellular drug release and thereby low therapeutic efficiency in cancer thermotherapy. Accordingly, in this dissertation, functional nanocapsules and nanoparticles including high drug loading liposome-like nanocapsules, high drug loading phospholipid-mimic nanocapsules with fast intracellular drug release, high drug loading charge-reversal nanocapsules, TAT based long blood circulation nanoparticles and charge-reversal nuclear targeted nanoparticles are designed and synthesized. These functional carriers have advantages such as high drug loading contents without premature drug release, fast cellular internalization and intracellular drug release, nuclear targeted delivery and long blood circulation. As a result, all these drug carriers show much higher in vitro and in vivo anti-cancer activities.

  14. Biohybrid Membrane Systems and Bioreactors as Tools for In Vitro Drug Testing.

    PubMed

    Salerno, Simona; Bartolo, Loredana De

    2017-01-01

    In drug development, in vitro human model systems are absolutely essential prior to the clinical trials, considering the increasing number of chemical compounds in need of testing, and, keeping in mind that animals cannot predict all the adverse human health effects and reactions, due to the species-specific differences in metabolic pathways. The liver plays a central role in the clearance and biotransformation of chemicals and xenobiotics. In vitro liver model systems by using highly differentiated human cells could have a great impact in preclinical trials. Membrane biohybrid systems constituted of human hepatocytes and micro- and nano-structured membranes, represent valuable tools for studying drug metabolism and toxicity. Membranes act as an extracellular matrix for the adhesion of hepatocytes, and compartmentalise them in a well-defined physical and chemical microenvironment with high selectivity. Advanced 3-D tissue cultures are furthermore achieved by using membrane bioreactors (MBR), which ensure the continuous perfusion of cells protecting them from shear stress. MBRs with different configurations allow the culturing of cells at high density and under closely monitored high perfusion, similarly to the natural liver. These devices that promote the long-term maintenance and differentiation of primary human hepatocytes with preserved liver specific functions can be employed in drug testing for prolonged exposure to chemical compounds and for assessing repeated-dose toxicity. The use of primary human hepatocytes in MBRs is the only system providing a faster and more cost-effective method of analysis for the prediction of in vitro human drug metabolism and enzyme induction alternative and/or complementary to the animal experimentation. In this paper, in vitro models for studying drug metabolism and toxicity as advanced biohybrid membrane systems and MBRs will be reviewed. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  15. Effects of Sublethal Exposure to a Glyphosate-Based Herbicide Formulation on Metabolic Activities of Different Xenobiotic-Metabolizing Enzymes in Rats.

    PubMed

    Larsen, Karen; Najle, Roberto; Lifschitz, Adrián; Maté, María L; Lanusse, Carlos; Virkel, Guillermo L

    2014-07-01

    The activities of different xenobiotic-metabolizing enzymes in liver subcellular fractions from Wistar rats exposed to a glyphosate (GLP)-based herbicide (Roundup full II) were evaluated in this work. Exposure to the herbicide triggered protective mechanisms against oxidative stress (increased glutathione peroxidase activity and total glutathione levels). Liver microsomes from both male and female rats exposed to the herbicide had lower (45%-54%, P < 0.01) hepatic cytochrome P450 (CYP) levels compared to their respective control animals. In female rats, the hepatic 7-ethoxycoumarin O-deethylase (a general CYP-dependent enzyme activity) was 57% higher (P < 0.05) in herbicide-exposed compared to control animals. Conversely, this enzyme activity was 58% lower (P < 0.05) in male rats receiving the herbicide. Lower (P < 0.05) 7-ethoxyresorufin O-deethlyase (EROD, CYP1A1/2 dependent) and oleandomycin triacetate (TAO) N-demethylase (CYP3A dependent) enzyme activities were observed in liver microsomes from exposed male rats. Conversely, in females receiving the herbicide, EROD increased (123%-168%, P < 0.05), whereas TAO N-demethylase did not change. A higher (158%-179%, P < 0.01) benzyloxyresorufin O-debenzylase (a CYP2B-dependent enzyme activity) activity was only observed in herbicide-exposed female rats. In herbicide-exposed rats, the hepatic S-oxidation of methimazole (flavin monooxygenase dependent) was 49% to 62% lower (P < 0.001), whereas the carbonyl reduction of menadione (a cytosolic carbonyl reductase-dependent activity) was higher (P < 0.05). Exposure to the herbicide had no effects on enzymatic activities dependent on carboxylesterases, glutathione transferases, and uridinediphospho-glucuronosyltransferases. This research demonstrated certain biochemical modifications after exposure to a GLP-based herbicide. Such modifications may affect the metabolic fate of different endobiotic and xenobiotic substances. The pharmacotoxicological significance of these

  16. Comparison of protein expression between human livers and the hepatic cell lines HepG2, Hep3B, and Huh7 using SWATH and MRM-HR proteomics: Focusing on drug-metabolizing enzymes.

    PubMed

    Shi, Jian; Wang, Xinwen; Lyu, Lingyun; Jiang, Hui; Zhu, Hao-Jie

    2018-04-01

    Human hepatic cell lines are widely used as an in vitro model for the study of drug metabolism and liver toxicity. However, the validity of this model is still a subject of debate because the expressions of various proteins in the cell lines, including drug-metabolizing enzymes (DMEs), can differ significantly from those in human livers. In the present study, we first conducted an untargeted proteomics analysis of the microsomes of the cell lines HepG2, Hep3B, and Huh7, and compared them to human livers using a sequential window acquisition of all theoretical mass spectra (SWATH) method. Furthermore, high-resolution multiple reaction monitoring (MRM-HR), a targeted proteomic approach, was utilized to compare the expressions of pre-selected DMEs between human livers and the cell lines. In general, the SWATH quantifications were in good agreement with the MRM-HR analysis. Over 3000 protein groups were quantified in the cells and human livers, and the proteome profiles of human livers significantly differed from the cell lines. Among the 101 DMEs quantified with MRM-HR, most were expressed at substantially lower levels in the cell lines. Thus, appropriate caution must be exercised when using these cell lines for the study of hepatic drug metabolism and toxicity. Copyright © 2018 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  17. Time-course comparison of xenobiotic activators of CAR and PPAR{alpha} in mouse liver

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ross, Pamela K.; Woods, Courtney G.; ExxonMobil Biomedical Sciences, Annandale, NJ

    Constitutive androstane receptor (CAR) and peroxisome proliferator activated receptor (PPAR){alpha} are transcription factors known to be primary mediators of liver effects, including carcinogenesis, by phenobarbital-like compounds and peroxisome proliferators, respectively, in rodents. Many similarities exist in the phenotypes elicited by these two classes of agents in rodent liver, and we hypothesized that the initial transcriptional responses to the xenobiotic activators of CAR and PPAR{alpha} will exhibit distinct patterns, but at later time-points these biological pathways will converge. In order to capture the global transcriptional changes that result from activation of these nuclear receptors over a time-course in the mouse liver,more » microarray technology was used. First, differences in basal expression of liver genes between C57Bl/6J wild-type and Car-null mice were examined and 14 significantly differentially expressed genes were identified. Next, mice were treated with phenobarbital (100 mg/kg by gavage for 24 h, or 0.085% w/w diet for 7 or 28 days), and liver gene expression changes with regards to both time and treatment were identified. While several pathways related to cellular proliferation and metabolism were affected by phenobarbital in wild-type mice, no significant changes in gene expression were found over time in the Car-nulls. Next, we determined commonalities and differences in the temporal response to phenobarbital and WY-14,643, a prototypical activator of PPAR {alpha}. Gene expression signatures from livers of wild-type mice C57Bl6/J mice treated with PB or WY-14,643 were compared. Similar pathways were affected by both compounds; however, considerable time-related differences were present. This study establishes common gene expression fingerprints of exposure to activators of CAR and PPAR{alpha} in rodent liver and demonstrates that despite similar phenotypic changes, molecular pathways differ between classes of chemical carcinogens.« less

  18. Effect of storage temperature on cultured epidermal cell sheets stored in xenobiotic-free medium.

    PubMed

    Jackson, Catherine; Aabel, Peder; Eidet, Jon R; Messelt, Edward B; Lyberg, Torstein; von Unge, Magnus; Utheim, Tor P

    2014-01-01

    Cultured epidermal cell sheets (CECS) are used in regenerative medicine in patients with burns, and have potential to treat limbal stem cell deficiency (LSCD), as demonstrated in animal models. Despite widespread use, short-term storage options for CECS are limited. Advantages of storage include: flexibility in scheduling surgery, reserve sheets for repeat operations, more opportunity for quality control, and improved transportation to allow wider distribution. Studies on storage of CECS have thus far focused on cryopreservation, whereas refrigeration is a convenient method commonly used for whole skin graft storage in burns clinics. It has been shown that preservation of viable cells using these methods is variable. This study evaluated the effect of different temperatures spanning 4°C to 37°C, on the cell viability, morphology, proliferation and metabolic status of CECS stored over a two week period in a xenobiotic-free system. Compared to non-stored control, best cell viability was obtained at 24°C (95.2±9.9%); reduced cell viability, at approximately 60%, was demonstrated at several of the temperatures (12°C, 28°C, 32°C and 37°C). Metabolic activity was significantly higher between 24°C and 37°C, where glucose, lactate, lactate/glucose ratios, and oxygen tension indicated increased activation of the glycolytic pathway under aerobic conditions. Preservation of morphology as shown by phase contrast and scanning electron micrographs was best at 12°C and 16°C. PCNA immunocytochemistry indicated that only 12°C and 20°C allowed maintenance of proliferative function at a similar level to non-stored control. In conclusion, results indicate that 12°C and 24°C merit further investigation as the prospective optimum temperature for short-term storage of cultured epidermal cell sheets.

  19. P-glycoprotein trafficking as a therapeutic target to optimize CNS drug delivery.

    PubMed

    Davis, Thomas P; Sanchez-Covarubias, Lucy; Tome, Margaret E

    2014-01-01

    The primary function of the blood-brain barrier (BBB)/neurovascular unit is to protect the central nervous system (CNS) from potentially harmful xenobiotic substances and maintain CNS homeostasis. Restricted access to the CNS is maintained via a combination of tight junction proteins as well as a variety of efflux and influx transporters that limits the transcellular and paracellular movement of solutes. Of the transporters identified at the BBB, P-glycoprotein (P-gp) has emerged as the transporter that is the greatest obstacle to effective CNS drug delivery. In this chapter, we provide data to support intracellular protein trafficking of P-gp within cerebral capillary microvessels as a potential target for improved drug delivery. We show that pain-induced changes in P-gp trafficking are associated with changes in P-gp's association with caveolin-1, a key scaffolding/trafficking protein that colocalizes with P-gp at the luminal membrane of brain microvessels. Changes in colocalization with the phosphorylated and nonphosphorylated forms of caveolin-1, by pain, are accompanied by dynamic changes in the distribution, relocalization, and activation of P-gp "pools" between microvascular endothelial cell subcellular compartments. Since redox-sensitive processes may be involved in signaling disassembly of higher-order structures of P-gp, we feel that manipulating redox signaling, via specific protein targeting at the BBB, may protect disulfide bond integrity of P-gp reservoirs and control trafficking to the membrane surface, providing improved CNS drug delivery. The advantage of therapeutic drug "relocalization" of a protein is that the physiological impact can be modified, temporarily or long term, despite pathology-induced changes in gene transcription. © 2014 Elsevier Inc. All rights reserved.

  20. CINPA1 Is an Inhibitor of Constitutive Androstane Receptor That Does Not Activate Pregnane X Receptor

    PubMed Central

    Cherian, Milu T; Lin, Wenwei; Wu, Jing

    2015-01-01

    Constitutive androstane receptor (CAR) and pregnane X receptor (PXR) are xenobiotic sensors that enhance the detoxification and elimination of xenobiotics and endobiotics by modulating the expression of genes encoding drug-metabolizing enzymes and transporters. Elevated levels of drug-metabolizing enzymes and efflux transporters, resulting from CAR activation in various cancers, promote the elimination of chemotherapeutic agents, leading to reduced therapeutic effectiveness and acquired drug resistance. CAR inhibitors, in combination with existing chemotherapeutics, could therefore be used to attenuate multidrug resistance in cancers. Interestingly, all previously reported CAR inverse-agonists are also activators of PXR, rendering them mechanistically counterproductive in tissues where both these xenobiotic receptors are present and active. We used a directed high-throughput screening approach, followed by subsequent mechanistic studies, to identify novel, potent, and specific small-molecule CAR inhibitors that do not activate PXR. We describe here one such inhibitor, CINPA1 (CAR inhibitor not PXR activator 1), capable of reducing CAR-mediated transcription with an IC50 of ∼70 nM. CINPA1 1) is a specific xenobiotic receptor inhibitor and has no cytotoxic effects up to 30 µM; 2) inhibits CAR-mediated gene expression in primary human hepatocytes, where CAR is endogenously expressed; 3) does not alter the protein levels or subcellular localization of CAR; 4) increases corepressor and reduces coactivator interaction with the CAR ligand-binding domain in mammalian two-hybrid assays; and 5) disrupts CAR binding to the promoter regions of target genes in chromatin immunoprecipitation assays. CINPA1 could be used as a novel molecular tool for understanding CAR function. PMID:25762023