In an effort to assess whether the craving for sweets experienced by some abstaining alcoholics is physiologically based, 48 Wistar rats were divided into 4 groups. Groups 1 and 3 were fed a liquid diet containing 35.5 percent energy as alcohol; groups 2 and 4 were fed a control diet with dextrins substituted for alcohol, all for 24 days. Group 4 was pair-fed to group 3. For the next 10 days, all rats were provided with sucrose and water ad libitum and all groups were continued on their liquid diet except that alcoholic group 3 was placed on the control diet and pair-fed group 4 was no longer pair-fed. Urine was collected at the end of the baseline, alcohol-induction, and recovery periods and analyzed for L-ascorbic acid. The mean consumption of sucrose was highest for rats still receiving alcohol and declined in all groups during the 10 days. The mean consumption of sucrose (% kcal as sucrose) for the first 4 days was 33.2, 19.5, 19.0, and 13.8% for groups 1, 2, 3, and 4 declining to 24.6, 11.2, 9.0, and 8.5 percent, respectively by the last 4 days. The sugar intake of alcoholic group 3 animals was significantly higher than pair-fed control group 4 during the first 4 days. L-ascorbic acid excretion was significantly increased in the groups receiving alcohol and declined during the recovery period. This study has raised the possibility that increased urinary excretion of ascorbic acid may suppress glycogen synthesis, leading to hypoglycemia. / Master of Science

Lee Kai Woo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 90-104). / Abstracts in English and Chinese. / Acknowledgements --- p.ii / Thesis Committee --- p.iii / Abstracts --- p.v / 論文槪要 --- p.vii / List of figures --- p.viii / List of abbreviations --- p.ix / Chapter Chapter one --- Introduction --- p.1 / Chapter 1.1 --- Drug metabolism and UGTs --- p.1 / Chapter 1.2 --- Natural substrates of UGTs --- p.4 / Chapter 1.3 --- Functions of UGT isoforms: roles of UGT polymorphisms --- p.6 / Chapter 1.4 --- Evolution of the UGT1 gene locus in vertebrates --- p.8 / Chapter 1.5 --- Multiple Variable First Exons: A Mechanism for Cell- and Tissue-Specific Gene regulation --- p.13 / Chapter 1.6 --- Evolutionary Origin of the Variable and Constant Genomic Organization --- p.14 / Chapter 1.7 --- Variable and Constant Genomic Organizations Exist in Mammalian UGTs --- p.20 / Chapter 1.8 --- The history of recombinant UGT expression --- p.20 / Chapter 1.9 --- UGT1A8 --- p.21 / Chapter 1.10 --- Licorice and its active component --- p.24 / Chapter 1.11 --- Enzyme induction in the liver --- p.25 / Chapter 1 12 --- Objectives --- p.28 / Chapter Chapter two --- Methods and Materials --- p.29 / Chapter 2.1 --- UGT1A8 induction studies --- p.30 / Chapter 2.1.1 --- Drug preparation --- p.30 / Chapter 2.1.2 --- Cell viability study with Neutral Red Assay Rat treatment --- p.30 / Chapter 2.1.3 --- Cell treatment --- p.31 / Chapter 2.1.4 --- Rat treatment --- p.31 / Chapter 2.1.5 --- RNA extraction from rat liver and cell culture --- p.31 / Chapter 2.1.6 --- Quantization of RNA --- p.32 / Chapter 2.1.7 --- Denaturing gel electrophoresis for RNA --- p.33 / Chapter 2.1.8 --- Northern hybridization --- p.33 / Chapter 2.1.9 --- Probe for Northern Blotting --- p.34 / Chapter 2.1.10 --- Agarose Gel analysis and Northern Blot analysis --- p.34 / Chapter 2.2 --- Recombinant expression of UGT1A8 in E.coli JM109 --- p.35 / Chapter 2.2.1 --- cDNA synthesis --- p.35 / Chapter 2.2.2 --- Polymerase chain reaction --- p.35 / Chapter 2.2.3 --- Agarose gel electrophoresis for DNA --- p.35 / Chapter 2.2.4 --- "Amplification of target gene, UGT1A8" --- p.36 / Chapter 2.2.5 --- Restriction enzyme digestion of plasmid and insert --- p.36 / Chapter 2.2.6 --- Ligation of plasmid and insert DNA --- p.37 / Chapter 2.2.7 --- Amplification of target plasmid --- p.37 / Chapter 2.2.8 --- Screening of target plasmid --- p.37 / Chapter 2.2.9 --- DNA sequencing --- p.38 / Chapter 2.2.10 --- Transformation of protein expression host --- p.38 / Chapter 2.2.11 --- Confirmation of transformation of protein expression host --- p.38 / Chapter 2.2.12 --- Protein expression --- p.39 / Chapter 2.2.13 --- Protein purification --- p.39 / Chapter 2.2.14 --- Sodium dodecyl sulfate polyacrylamide gel electrophoresis --- p.40 / Chapter 2.2.15 --- Confirmation of the protein --- p.40 / Chapter 2.3 --- Characterization of recombinant UGT1A8 --- p.41 / Chapter 2.3.1 --- UGT assay --- p.41 / Chapter 2.4 --- Routine experiment methods --- p.41 / Chapter 2.4.1 --- Determination of protein --- p.41 / Chapter 2.4.2 --- Nucleic acid purification --- p.42 / Chapter 2.4.3 --- Preparation of chemically competent bacterial cells --- p.42 / Chapter 2.4.4 --- Colony PCR --- p.43 / Chapter 2.4.5 --- Plasmid rescue by alkaline lysis --- p.44 / Chapter 2.4.6 --- Charging of His-tagged column --- p.44 / Chapter 2.4.7 --- Washing of His-tagged column --- p.45 / Chapter Chapter three --- Results --- p.46 / Chapter 3.1 --- UGT1A8 Expression in clone9 and H4IIE after treatment with licorice and 18 β glycyrrhentinic acid --- p.46 / Chapter 3.2 --- UGT1A8 induction in wistar and j/j rats after treatment --- p.63 / Chapter 3.3 --- Construction of pRset-UGT 1A8 Vector --- p.70 / Chapter 3.4 --- Purification of recombinant UGT1A8 --- p.75 / Chapter 3.5 --- Screening of substrate of the purified enzyme --- p.77 / Chapter Chapter four --- Discussion --- p.78 / Chapter 4.1 --- Effects of licorice and 18βglycyrrhetinic acid in the induction of UGT1A8 in different cell lines --- p.78 / Chapter 4.2 --- Comparison of wistar and j/j rats in the induction of UGT1A8 --- p.79 / Chapter 4.3 --- Comparison of licorice and 18(3 glycyrrhetinic acid in the induction of UGT1A8 in rats --- p.81 / Chapter 4.4 --- Comparison of in vivo and in vitro of drug treatment --- p.81 / Chapter 4.5 --- Expression of UGT1A7 after drug treatment in vitro --- p.82 / Chapter 4.6 --- Protein expression and purification --- p.83 / Chapter 4.7 --- Substrates of UGT1A8 --- p.83 / Chapter Chapter Five --- Conclusions --- p.86 / References --- p.90 / Appendix --- p.105

<p>Enzyme induction is a process whereby a molecule enhances the expression of enzymes. If the affected enzymes are involved in the elimination of a drug, this may result in a drug interaction. Induction is therefore of major concern during drug development and in clinical practice. </p><p>The induction process depends on the half-life of the induced enzyme, the pharmacokinetics of the inducing agent, and the relationship between the inducer’s concentration and the induction stimulus. The aim of the conducted research was to investigate these key aspects of enzyme induction and the consequences that induction has for substrate elimination.</p><p>Successful investigations of the induction process presuppose the existence of appropriate methods for the estimation of the metabolic activity. Enzyme activity measurements can be conducted in tissues with low enzyme content using the analytical method presented here. </p><p>A model was developed describing the changes in the pharmacokinetics of clomethiazole and its metabolite NLA-715, that are attributable to carbamazepine induction. The consequences of the induction was explained using a mechanistic approach, acknowledging food-induced changes in the blood flow to the liver, and interpreting in vitro generated metabolic information.</p><p>The time course of the induction process was examined in two investigations. In the first of these, the pharmacokinetics of the autoinducing drug phenobarbital and its effect on several enzymes were described in rats. This was accomplished by integrating the bidirectional interaction between drug and enzymes in a mechanistic manner. In the final investigation, the time course of the increase and cessation in enzyme activity was studied in healthy volunteers treated with carbamazepine. This investigation allowed the half-lives of CYP3A and CYP1A2 to be estimated. </p><p>The key aspects of the enzyme induction process have been examined using mechanistic induction models. These novel models improve the understanding of the induction process and its consequences for substrate elimination.</p>

Enzyme induction is a process whereby a molecule enhances the expression of enzymes. If the affected enzymes are involved in the elimination of a drug, this may result in a drug interaction. Induction is therefore of major concern during drug development and in clinical practice. The induction process depends on the half-life of the induced enzyme, the pharmacokinetics of the inducing agent, and the relationship between the inducer’s concentration and the induction stimulus. The aim of the conducted research was to investigate these key aspects of enzyme induction and the consequences that induction has for substrate elimination. Successful investigations of the induction process presuppose the existence of appropriate methods for the estimation of the metabolic activity. Enzyme activity measurements can be conducted in tissues with low enzyme content using the analytical method presented here. A model was developed describing the changes in the pharmacokinetics of clomethiazole and its metabolite NLA-715, that are attributable to carbamazepine induction. The consequences of the induction was explained using a mechanistic approach, acknowledging food-induced changes in the blood flow to the liver, and interpreting in vitro generated metabolic information. The time course of the induction process was examined in two investigations. In the first of these, the pharmacokinetics of the autoinducing drug phenobarbital and its effect on several enzymes were described in rats. This was accomplished by integrating the bidirectional interaction between drug and enzymes in a mechanistic manner. In the final investigation, the time course of the increase and cessation in enzyme activity was studied in healthy volunteers treated with carbamazepine. This investigation allowed the half-lives of CYP3A and CYP1A2 to be estimated. The key aspects of the enzyme induction process have been examined using mechanistic induction models. These novel models improve the understanding of the induction process and its consequences for substrate elimination.

Abstract The cytochrome P450 (CYP) enzyme system in human lung is an essential component in the pulmonary carcinogenicity of several inhaled xenobiotic compounds. The aim of this study was to elucidate the expression and regulation of xenobiotic-metabolizing CYP enzymes in human lung. To evaluate which of the two is a better surrogate cell model for lung tissue, the expression patterns of CYP enzymes in alveolar macrophages and peripheral blood lymphocytes were clarified by reverse transcriptase-polymerase chain reaction (RT-PCR) and compared to the expression in lung tissue. The pattern of CYP expression in alveolar macrophages was found to closely resemble the expression pattern in human lung tissue, while the pattern in lymphocytes was markedly different. The expression of CYP2B6, CYP2C, CYP3A5, and CYP4B1 mRNAs in alveolar macrophages was demonstrated for the first time. To facilitate mechanistic studies on human pulmonary CYP induction, the A549 lung adenocarcinoma cell line was characterized by RT-PCR, and the CYP expression pattern was found to compare reasonably well to human lung epithelial cells. The induction of CYP1A1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) behaved as predicted, and CYP1B1 and CYP3A5 were also inducible by TCDD and dexamethasone, respectively. TCDD elevated the level of CYP1A1 mRNA (56-fold), while the induction of CYP1B1 mRNA was more modest (2.5-fold). The tyrosine kinase inhibitor genistein and the protein kinase C inhibitor staurosporine blocked CYP1A1 induction by TCDD, but did not affect CYP1B1 induction. The serine/threonine protein phosphatase inhibitor calyculin A and okadaic acid enhanced CYP1B1 induction slightly, but did not alter CYP1A1 induction. The expression of CYP3A forms in human pulmonary tissues was studied with RT-PCR and immunohistochemistry, and both methods established CYP3A5 as the main CYP3A form. CYP3A4 was expressed in only about 20% of the cases. In A549 cells, CYP3A5 was induced about 4-fold by the glucocorticoids budesonide, beclomethasone dipropionate, and dexamethasone. Maximal induction was achieved by concentrations as low as ~100 nM, suggesting that CYP3A5 could be induced in vivo in patients using inhaled glucocorticoids. However, there were no differences in CYP3A5 expression in alveolar macrophages in current glucocorticoid users, ex-users, and non-users. Cigarette smoking had a marked decreasing effect on CYP3A5 levels in alveolar macrophages. The presence and possible induction of CYP3A5 by glucocorticoids in human lung could have consequences for the maintenance of physiological steroid hormone balance in lung and the individual susceptibility to lung cancer of patients using glucocorticoids.

No description available.

Issue d’un partenariat de recherche entre le CEA et les laboratoires Servier, cette thèse avait pour objectif d’évaluer l’approche métabolomique par chromatographie liquide couplée à la spectrométrie de masse (LC-MS) pour l'identification de marqueurs indirects de l'induction dans les espèces de toxicologie. Le travail de thèse a débuté par l’optimisation de la méthode d’acquisition des empreintes métaboliques tant sur le plan analytique que dans le domaine du traitement des données brutes. Un outil reposant sur les matrices d’auto corrélation a alors été développé afin de s’affranchir d’une partie de la redondance du signal obtenu par spectrométrie de masse. Dans un troisième temps, les indices de Kendrick couplés à la sélectivité méthylène ont été appliqués à l’étude de composés biologiques en spectrométrie de masse haute résolution afin de proposer une méthode alternative de visualisation des données offrant une aide à l’identification des variables. Enfin, dans une dernière partie, les efforts se sont portés sur l’identification des composés endogènes modifiés au cours du protocole d’induction. / This work is the result of a research partnership between the CEA and Les laboratories Servier. It deals with the characterization of biomarkers of metabolic enzyme induction in rat biofluids using MSbased metabolomics. The first part of this work included methodological developments regarding theacquisition and the processing of metabolic fingerprints. A tool based on autocorrelation matrices wasthen implemented to reduce the redundancy of data generated with mass spectrometry and subsequently accelerate the isolation of discriminating variables. The next step consisted in the evaluation of the combined use of Kendrick mass defects and methylene selectivity as an alternative visualization tool for large data set, which would rely on compound chemical structures. Finally, the last part of the work was dedicated to the identification of discriminating signals raised up by ametabolomic global approach from rat biofluids collected before and after an induction assay.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

5-Aminolevulinic acid synthase-1 (ALAS-1) is the first and normally rate-controlling enzyme for hepatic heme biosynthesis. ALAS-1 is highly inducible, especially in liver, in response to changes in nutritional status, and to drugs that induce cytochrome P-450. The critical biochemical abnormality of the acute porphyrias, a group of disorders of heme synthesis, is an uncontrolled up-regulation of ALAS-1. High intakes of glucose or other metabolizable sugars and intravenous heme are the cornerstones of therapy for acute attacks of porphyrias and both repress the over-expression ALAS-1, although their mechanisms of action have not been fully characterized. In this work, the chick hepatoma cell line, LMH, was characterized with respect to its usefulness in studies of heme biosynthesis and compared with chick embryo liver cells (CELCs), a widely used model for studies of heme metabolism. The inducibility of ALAS-1 mRNA and enzyme activity and accumulation of porphyrins by chemicals were used to evaluate heme biosynthesis in LMH cells. Repression of ALAS-1 mRNA and induced activity by exogenous heme (20 μM) was shown to occur in LMH cells as in CELCs. In addition, a synergistic induction of ALAS-1 enzyme activity was observed in LMH cells, as shown previously in CELCs, by treatment with a barbiturate-like chemical, Glutethimide (Glut), in combination with an inhibitor of heme synthesis, 4,6-dioxoheptanoic acid (DHA). This induction of ALAS-1 enzyme activity is analogous to what occurs in patients with acute hepatic porphyrias and LMH cells were used to further characterize effects of Glut, DHA, glucose, and heme on ALAS-1. A "glucose effect" to decrease Glut and DHA-induced ALAS-1 enzyme activity was obtained in LMH cells and CELCs in the absence of serum or hormones. This "glucose effect" was further characterized in LMH cells using a construct containing approximately 9.1 kb of chick ALAS-1 5'- flanking and 5' -UTR region attached to a luciferase/reporter gene (pGcALAS9.1-Luc). Glut (50 μM) and DHA (250 μM) synergistically induced luciferase activity (5-fold) in LMH cells transiently transfected with pGcALAS9.l-Luc. Addition of glucose (11 or 33 mM), in a dose-dependent manner, decreased the Glut+DHA up-regulation of pGcALAS9.1-Luc activity. Gluconeogenic or glycolytic substrates such as fructose, galactose, glycerol and lactate, but not the non-metabolizable sugar sorbitol, also down-regulated pGcALAS9.1-Luc in LMH cells. The cAMP analog 8-CPT-cAMP, augmented Glut induction of ALAS-1, indicating that the glucose effect may be partly mediated by changes in cAMP levels. The remaining studies focused on delineating the synergistic effect of Glut and DHA, and heme-dependent repression of ALAS-1. The 9.1 kb construct was compared with a construct containing the first 3.5 kb (pGcALAS3.5-Luc). The drug and heme effects were shown to be separate as drug induction was present in -3.4 to +0.082 kb region while the heme responsiveness was present in the -9.1 to -3.4 kb region. Using computer sequence analysis, several consensus activator protein-1 (AP-1) sites were found in the 9.1 kb ALAS-1 sequence but no consensus direct repeat (DR)-4 or DR-5 type recognition sequences for nuclear receptors were identified in the drug-responsive 3.5 kb region. Deletion constructs containing +0.082 to -7.6 kb (pGcALAS7.6-Luc) and +0.082 to -6.2 kb (pGcALAS6.3-Luc) cALAS 5'- flanking and 5' - UTR region were generated and tested and pGcALAS6.3-Luc was shown to have heme-dependent repression of basal and Glut and DHA-induced activity. A recently identified 167 bp chick ALAS-1 drug responsive enhancer (DRE) was PCR amplified and inserted upstream of the 9.1 kb (pGcALAS9.1+DRE), a 0.399 kb (+0.082 to -0.317) (pGcALAS0.3+DRE), and pGL3SV40 construct (pGL3SV40+DRE). DRE mediated the up-regulation of pGL3SV40+DRE construct by Glut was ~ 15-30 fold but interestingly only 3.2 and 3.7-fold for pGcALAS9.l +DRE and pGcALAS0.3+DRE constructs, respectively. In summary, in LMH cells drugs up-regulate ALAS-1 through non-DRE element(s) in the first 3.5 kb of ALAS-1 5'-flanking and 5'-UTR region and heme down-regulates ALAS-1 and determines the extent of the drug response through element(s) in the -6.3 to -3.5 kb region of ALAS-1 5'- flanking region.

No description available.