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Topic: Xenobiotic

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	Xenobiotic Summary
		A xenobiotic is a chemical which is found in an organism but which is not normally produced or expected to be present in it.
		Hepatic enzymes are responsible for the metabolism of xenobiotics, by first activating them (oxidation, reduction, hydrolysis and/or hydration of the xenobiotic) and then conjugating the active secondary metabolite with glucuronic or sulphuric acid, or glutathione, followed by excretion in bile or urine.
		Xenobiotic organs would need to be developed in such a way that they would not be rejected by the immune system.
	www.bookrags.com /Xenobiotic (481 words)

	Xenobiotic - Wikipedia, the free encyclopedia
		A xenobiotic is a chemical which is found in an organism but which is not normally produced or expected to be present in it.
		For example, drugs such as antibiotics are human xenobiotics because the human body does not produce them itself nor would they be expected to be present as part of a normal diet.
		Xenobiotic organs would need to be developed in such a way that they would not be rejected by the immune system.
	en.wikipedia.org /wiki/Xenobiotic (218 words)

	Xenobiotics
		Xenobiotics are chemicals found in organisms, but not expected to be produced or present in them; or they are chemicals found in much higher concentrations than usual.
		An example of a xenobiotic is an antibiotic; the human body does not produce them, and they are not expected to be present in the normal human diet.
		Xenobiotics are eliminated from the body through xenobiotic metabolism, in which the xenobiotic is deactivated and secreted away from the body.
	www.iscid.org /encyclopedia/Xenobiotics (235 words)

	Oxford Biomedical Research (800) 692-4633
		Xenobiotics are molecules that are not produced in vivo but which are introduced into the body from the environment and subsequently metabolized by the body.
		Since ingestion is a primary route of exposure to xenobiotics, and xenobiotics adsorbed by other routes typically pass quickly through the hepatic portal circulation, the liver is a key site for detoxification and most studies of xenobiotic metabolism have focused on the liver.
		Xenobiotic metabolism and oxidative stress: The metabolism of xenobiotics, in particular mixed function oxygenases in Phase I, generates free radicals.
	www.oxfordbiomed.com /pathxeno.html (975 words)

	Center for Cancer Research - Staff Pages
		Xenobiotic receptors are thought to mediate the mechanism of action of nongenotoxic carcinogens.
		To determine the functions of xenobiotic-metabolizing enzymes and xenobiotic receptors in mammalian development and physiology and their role in toxicity and carcinogenesis, gene nullizygous mice have been produced using targeted gene disruption in embryonic stem cells.
		Genes encoding xenobiotic receptors and P450s are sequences, and exon-crossing primers are generated for use in screening human populations for novel functional mutations.
	ccr.nci.nih.gov /Staff/Staff.asp?StaffID=723 (561 words)

	Allometric Scaling of Xenobiotic Clearance: Uncertainty versus Universality
		From the normalized CL values, 4 xenobiotic subgroups were examined: those that were (i) protein, and those that were (ii) eliminated mainly by renal excretion, (iii) by metabolism, or (iv) by renal excretion and metabolism combined.
		We combined a statistical analysis of the allometric exponent of clearance from 115 xenobiotics and a Monte Carlo simulation to characterize the uncertainty in the allometric exponent for clearance and to investigate whether a universal exponent may exist for the scaling of xenobiotic clearance.
		The regression slope was 0.74, and the 99% CI was 0.71 to 0.76.
	www.aapspharmsci.org /view.asp?art=ps030429 (4589 words)

	Lupus-Prone Mice as Models to Study Xenobiotic-Induced Acceleration of Systemic Autoimmunity
		Analysis of the role of xenobiotics in autoimmunity, particularly in humans, is hampered by identification of potentially sensitive populations.
		Xenobiotics selected for study were two metals, mercury and nickel, known to produce distinctly different immunologic responses.
		In this study, particular emphasis was placed on the potential of these xenobiotics to exacerbate the natural course of systemic autoimmune disease in lupus-prone mice as revealed by lymphadenopathy, elevations of serum immunoglobulin, appearance of autoantibodies, and immune complex deposits.
	ehp.niehs.nih.gov /members/1999/suppl-5/729-735pollard/pollard-full.html (4885 words)

	NIH-CSR Digestive Sciences IRG [DIG]
		Xenobiotic and SP nutrient-mediated alterations in signal transduction, cell cycle regulation, receptors, genes, apoptosis and/or oncosis (necrosis).
		Studies could be directed to XNDA when they address the effects of digestive system-generated metabolites of xenobiotics or the absorption and excretion of xenobiotics by the digestive system or where multiple organ systems are involved or where the hepatic and /or gastrointestinal activities dominate.
		General studies of the disposition of xenobiotics, biopharmaceutical agents, phytochemicals/ botanicals, and other non-drug chemicals, and the study of their mechanisms of action, particularly when they relate to normal and pathological conditions of the digestive system, may be assigned to XNDA.
	cms.csr.nih.gov /PeerReviewMeetings/CSRIRGDescription/DIGIRG/DIGIRGAll.htm (7965 words)

	Patent 6,756,229
		Throughout the specification, the term "xenobiotics or foreign matters in vivo" collectively refers to, e.g., medicaments, food additives, environmental pollutants, chemicals in general, etc. and the term "endogenous substrates" refers to all substances present in vivo.
		Specific examples include identification of an enzyme participating the metabolism of xenobiotics and/or endogenous substrates by analyzing a change in the structure of xenobiotics and/or endogenous substrates upon exposure of a test specimen to the human hepatic carcinoma-derived cultured cell line capable of stably expressing cytochromes P450.
		The hepatotoxicity by the metabolism of xenobiotics and/or endogenous substrates can be analyzed by exposing a test specimen, e.g., to the human hepatic carcinoma-derived cultured cell line capable of stably expressing cytochromes P450 and then observing the expression of cytotoxicity.
	www.pharmcast.com /Patents100/Yr2004/June2004/062904/6756229_CellLine062904.htm (3316 words)

	[No title] (Site not responding. Last check: 2007-11-05)
		Therefore, the efficient detoxification of harmful xenobiotics is essential to the survival of all organisms.
		xenobiotic compound can be considered"cleared"when the compound is removed from the cell, tissue, organ or organism of interest, or converted or modified to a different chemical form, e.
		Compounds include steroids and/or xenobiotics, whether such compounds are endogenously produced, result from dietary sources, or are therapeutically administered to a subject in treatment of a particular disease state.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=03/05812.030123&ELEMENT_SET=DECL (10811 words)

	Cytochrome P450 Enzymes and Nuclear Receptors for Metabolism of Steroids and Xenobiotics --- New Venues for Novel Drug ...
		These enzymes are expressed in both the gastrointestinal tract and hepatic microsomes, and the activity may vary between 6- and 30-fold among individuals due to genetic and nongenetic factors such as drug therapy.
		In this case, when steroid and xenobiotic receptor (SXR) that is a human homolog to mouse PXR was transduced into the mouse, the transgenics expressed CYP3A gene constitutively and enhanced protection of the mice against toxic compounds.
		Xenobiotics induce the transcription of CYP2B through CAR, and when systematically compared with a series of xenobiotics and natural steroids, CAR for CYP2B exhibited marked pharmacological differences from those of PXR for CYP3A.
	ihumans.com /news_comments_archive/XenobioticsP450Enz.html (969 words)

	Structure-Activity Relationships for Xenobiotic Transport Substrates and Inhibitory Ligands of P-glycoprotein
		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.
		P-gp in humans is located on the secretory surfaces of organs of elimination, such as the brush border of the renal proximal tubules, the canalicular membrane of hepatocytes, and the apical surface of mucosal cells in the small and large intestines (2).
	ehp.niehs.nih.gov /members/1997/105-8/bain-full.html (4649 words)

	Center for Phytoremediation Research and Development
		Applegate’s major role in the project will be to directly supervise the identification of genes involved in degradation of xenobiotics in the rhizosphere.
		Applegate has extensive experience in the microbiology and molecular biology of xenobiotic degradation and sensor development, making him very well qualified to lead this portion of the Center’s activities.
		He is also interested in developing high-throughput screens for the identification of enzymes involved in xenobiotic degradation.
	www.purdue.edu /DiscoveryPark/phytoremediation/participants.html (672 words)

	United States Patent Application: 0040213771
		The method of claim 44, wherein the modulator is an antagonist, and wherein the amount or activity of the xenobiotic sensing NR in the sensitized nematode is reduced relative to the amount or activity of the xenobiotic sensing NR in the absence of the modulator.
		A nuclear receptor that responds to the presence of a xenobiotic by playing a role in a pathway (e.g., a physiologic or biochemical pathway) that affects the metabolism or biotransformation of the compound is referred to herein as a xenobiotic sensing nuclear receptor.
		In vertebrates, NR activated metabolism of xenobiotic compounds occurs primarily in the liver.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtml/PTO/search-adv.html&r=5&p=1&f=G&l=50&d=PG01&S1=causey.IN.&OS=in/causey&RS=IN/causey (15024 words)

	Highly chlorinated PCBs inhibit the human xenobiotic response mediated by the steroid and xenobiotic receptor - SXR - ...
		The mammalian xenobiotic response is mediated primarily by two broad-specificity sensors: the orphan nuclear receptors SXR/PXR (human steroid and xenobiotic receptor/rodent pregnane X receptor) (Blumberg et al.
		These findings suggest more broadly that the literature concerning the effects of xenobiotic chemicals and the attendant risks for human and wildlife populations will need to be reevaluated where the behavior of xenobiotic sensors differs across species.
		The differential metabolism of drugs, xenobiotics, and dietary compounds mediated by SXR/PXR provides both an explanation and a molecular tool with which to address the often contradictory and controversial literature on the effects of dietary and environmental chemicals on human health.
	findarticles.com /p/articles/mi_m0CYP/is_2_112/ai_114559349 (1015 words)

	Environmentally Induced Autoimmune Diseases: Potential Mechanisms
		Xenobiotics can modify gene expression in lymphocytes as well as antigen-presenting cells by acting on receptors, their signaling pathways, or at the DNA level.
		All are susceptible to modification by xenobiotics, usually in a synergistic fashion, and at least two lupus-inducing drugs, procainamide and hydralazine, have effects on this regulatory mechanism.
		Although the mechanism by which xenobiotic endocrine disrupters contribute to autoimmunity remains obscure, the potential contribution of these agents to autoimmunity remains a valid concern.
	www.ehponline.org /members/1999/suppl-5/737-742rao/rao-full.html (6323 words)

	Xenobiotic-Induced Loss of Tolerance in Rabbits to the Mitochondrial Autoantigen of Primary Biliary Cirrhosis Is ...
		After this conjugation to agarose, xenobiotics (R) were added to the lysine of the peptide.
		Twenty-three xenobiotics and lipoic acid coupled to either the 12-mer, PDC peptide, mutant PDC peptide, and/or control albumin peptide were spotted.
		Immunization with a xenobiotic 6-bromohexanoate bovine serum albumin conjugate induces antimitochondrial antibodies.
	www.jimmunol.org /cgi/content/full/172/10/6444 (4782 words)

	xenobiotic, Primary Sclerosing Cholangitis Literature
		Kemp DC, Zamek-Gliszczynski MJ, Brouwer KL 2005 Xenobiotics inhibit hepatic uptake and biliary excretion of taurocholate in rat hepatocytes.
		Lampen A, Ebert B, Stumkat L, Jacob J, Seidel A 2004 Induction of gene expression of xenobiotic metabolism enzymes and ABC-transport proteins by PAH and a reconstituted PAH mixture in human Caco-2 cells.
		Meyer UA, Gut J 2002 Genomics and the prediction of xenobiotic toxicity.
	home.insightbb.com /~rhodesdavid/xeno.htm (10748 words)

	Alibris: Xenobiotics
		Discusses the metabolism and fate of xenobiotic compounds, such as veterinary drugs, agrochemicals, and other products to which food-producing animals are exposed.
		Highlights advances in the understanding of the biosynthesis of xenobiotic conjugates in mammals, fish, insects, and plants.
		Many of the toxic effects elicited by xenobiotics can be explained at the molecular level by their interaction with receptors or by disruption or interference with receptor-mediated signal transduction pathways.
	www.alibris.com /search/books/subject/Xenobiotics (844 words)

	Bioavailability of aged xenobiotic residues
		Aged xenobiotic residues are chemicals of anthropogenic origin and their metabolites.
		To which degree these also called "non-extractable" residues actually occur in soil depends strongly on the physical and chemical properties of the compound, the soil properties including the microorganism spectra and their activity as well as on climatic factors and cultivation practices.
		After remobilisation of the aged xenobiotics these compounds may be metabolised, exhibit biological activity or transported to the underlying aquifers.
	www.fz-juelich.de /icg/icg-iv/index.php?index=471 (236 words)

	Proposed Competencies for PSC3310, Principles of Drug Disposition:
		Compare and contrast the effects of various routes of xenobiotic administration on the onset, intensity, and duration of pharmacologic effect.
		Identify the 4 factors that determine the extent of xenobiotic distribution in the body.
		Identify 4 factors that influence the degree by which a xenobiotic is eliminated via the renal route.
	www.uiowa.edu /~c046138/kineticscomp.htm (845 words)

	Organic Xenobiotic Laboratory
		This lab will be used for measuring physico-chemical properties of organic compounds (e.g., aqueous solubility, Henry's law constants, and octanol-water partition coefficients), kinetics of transformation of organic xenobiotic compounds under environmentally-relevant conditions, and sorption rates and equilibrium concentrations.
		Concentrations of xenobiotic compounds in natural samples from air, water, and sediment will also be analyzed.
		The general goal of the research conducted is to further the ability to predict xenobiotic compound fate and transport based on molecular structure.
	www.cee.mtu.edu /facility/oxl.html (186 words)

	Amazon.com: xenobiotic (Site not responding. Last check: 2007-11-05)
		Nasal Toxicity And Dosimetry Of Inhaled Xenobiotics by Fred J. Miller and Gary A. Boorman (Library Binding - Jan 1995)
		A methodology for ranking and hazard identification of xenobiotic organic compounds in urban stormwater [An article from: Science of the Total Environment, The] by A. Baun, E. Eriksson, A. Ledin, and P.S. Mikkelsen (Oct 15, 2006)
		Xenobiotics and Food-Producing Animals: Metabolism and Residues (Acs Symposium Series) by D. Hutson, D. Hawkins, G. Paulson, and C. Struble (Hardcover - Jun 11, 1998)
	www.amazon.com /s?ie=UTF8&keywords=xenobiotic&index=blended&page=1 (713 words)

	Simulating Metabolism of Xenobiotic Chemicals as a Predictor of Toxicity > National Center for Computational ...
		Metabolically-competent liver slices from male fish that produce vitellogenin when exposed to xenobiotics interacting with the ER will be used to study chemical bioactivation to ER-active forms.
		Data from these studies are used to improve the metabolic simulator and used to prioritize chemicals for testing that have the potential to be bioactivated to more toxic species.
		Thus, an approach that integrates metabolism simulation with toxic effects modeling will be demonstrated and will provide prioritized lists of chemicals and their metabolites most likely to present the greatest risk for ER mediated endocrine disruption.
	www.epa.gov /nhrlsup1/comptox/new_start/xenobiotic.html (623 words)

	Environmental Health Perspectives: Highly chlorinated PCBs inhibit the human xenobiotic response mediated by the ...
		The mammalian xenobiotic response is mediated primarily by two broad-specificity sensors: the orphan nuclear receptors SXR/PXR (human steroid and xenobiotic receptor/rodent pregnane X receptor) (Blumberg et al.
		These findings suggest more broadly that the literature concerning the effects of xenobiotic chemicals and the attendant risks for human and wildlife populations will need to be reevaluated where the behavior of xenobiotic sensors differs across species.
		The differential metabolism of drugs, xenobiotics, and dietary compounds mediated by SXR/PXR provides both an explanation and a molecular tool with which to address the often contradictory and controversial literature on the effects of dietary and environmental chemicals on human health.
	www.findarticles.com /p/articles/mi_m0CYP/is_2_112/ai_114559349 (1387 words)

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