Dissertations / Theses on the topic 'Detoxification enzymes'
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Boucher, Ian. "Structural studies of enzymes involved in cell detoxification." Thesis, University of York, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437619.
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Chalmers, D. "Chemical carcinogenesis : Studies on detoxification enzymes in somatic cell hybrids." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371997.
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Labuschagne, Jeanine. "Molecular methods for genotyping selected detoxification and DNA repair enzymes / J. Labuschagne." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4599.
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The emerging field of personalized medicine and the prediction of side effects experienced due to pharmaceutical drugs is being studied intensively in the post genomic era. The molecular basis of inheritance and disease susceptibility is being unravelled, especially through the use of rapidly evolving new technologies. This in turn facilitates analyses of individual variations in the whole genome of both single subjects and large groups of subjects.
Genetic variation is a common occurrence and although most genetic variations do not have any apparent effect on the gene product some do exhibit effects, such as an altered ability to detoxify xenobiotics.
The human body has a highly effective detoxification system that detoxifies and excretes endogenous as well as exogenous toxins. Numerous studies have proved that specific genetic variations have an influence on the efficacy of the metabolism of pharmaceutical drugs and consequently the dosage administered.
The primary aim of this project was the local implementation and assessment of two different genotyping approaches namely: the Applied Biosystems SNaPshot technique and Affymetrix DMET microarray. A secondary aim was to investigate if links could be found between the genetic data and the biochemical detoxification profile of participants. I investigated the approaches and gained insight into which method would be better for specific local applications, taking into consideration the robustness and ease of implementation as well as cost effectiveness in terms of data generated.
The final study cohort comprised of 18 participants whose detoxification profiles were known. Genotyping was performed using the DMET microarray and SNaPshot techniques. The SNaPshot technique was used to genotype 11 SNPs relating to DNA repair and detoxification and was performed locally. Each DMET microarray delivers significantly more data in that it genotypes 1931 genetic markers relating to drug metabolism and transport. Due to the absence of a local service supplier, the DMET - microarrays were outsourced to DNALink in South Korea. DNALink generated raw data which was analysed locally.
I experienced many problems with the implementation of the SNaPshot technique. Numerous avenues of troubleshooting were explored with varying degrees of success. I concluded that SNaPshot technology is not the best suited approach for genotyping. Data obtained from the DMET microarray was fed into the DMET console software to obtain genotypes and subsequently analysed with the help of the NWU statistical consultation services. Two approaches were followed: firstly, clustering the data and, secondly, a targeted gene approach. Neither of the two methods was able to establish a relationship between the DMET genotyping data and the detoxification profiling.
For future studies to successfully correlate SNPs or SNP groups and a specific detoxification profile, two key issues should be addressed: i) The procedure for determining the detoxification profile following substrate loading should be further refined by more frequent sampling after substrate loading. ii) The number of participants should be increased to provide statistical power that will enable a true representation of the particular genetic markers in the specific population. The statistical analyses, such as latent class analyses to cluster the participants will also be of much more use for data analyses and interpretation if the study is not underpowered.Thesis (M.Sc. (Biochemistry))--North-West University, Potchefstroom Campus, 2011.
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Cheung, Ka-hong. "Chromate toxicity assessment and detoxification by bacteria from the marine environment /." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36249890.
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Cheung, Ka-hong, and 張嘉康. "Chromate toxicity assessment and detoxification by bacteria from the marine environment." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B45015351.
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Whalen, Kristen Elizabeth. "Functional characterization and expression of molluscan detoxification enzymes and transporters involved in dietary allelochemical resistance." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43228.
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Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2008.Page 362 blank.
Includes bibliographical references.
Understanding how organisms deal with potentially toxic or fitness-reducing allelochemicals is important for understanding patterns of predation and herbivory in the marine environment. The ability of marine consumers to tolerate dietary toxins may involve biochemical resistance mechanisms, which increase the hydrophilicity of compounds and facilitate their active efflux out of sensitive cells and tissues. While several allelochemical-responsive detoxification enzymes have been sequenced and functionally characterized in terrestrial invertebrates feeding on chemically defended host plants, there is virtually no information concerning the role of these biotransformation enzymes that may mediate feeding tolerance in marine invertebrates. The objective of this research was to assess the diversity and dietary regulation of cytochrome P450s (CYP), glutathione S-transferases (GST) and ABC transporters in the generalist marine gastropod Cyphoma gibbosum feeding on a variety of chemically defended gorgonian corals, and to identify those dietary natural products that act as substrates for these proteins. Molecular and proteomic techniques identified both allelochemically-responsive CYPs, and constitutively expressed GSTs and transporters in Cyphoma digestive glands. Inhibition of Cyphoma GST activity by gorgonian extracts and selected allelochemicals (i.e., prostaglandins) indicated that gorgonian diets are likely to contain substrates for molluscan detoxification enzymes. In vitro metabolism studies with recombinant CYPs suggested those Cyphoma enzymes most closely related to vertebrate fatty acid hydroxylating enzymes may contribute to the detoxification ofichthyodeterrent cyclopentenone prostaglandins found in abundance in selected gorgonian species.
(cont.) Finally, the presence and activity of multixenobiotic resistance transporters in Cyphoma and the co-occurring specialist nudibranch, Tritonia hamnerorum, suggests these efflux transporters could function as a first line of defense against dietary intoxication. Together, these results suggest marine consumers that regularly exploit allelochemical-rich prey have evolved both general (GST and ABC transporters) and allelochemical-specific (CYP) detoxification mechanisms to tolerate prey chemical defenses.
by Kristen Elizabeth Whalen.
Ph.D.
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Cavka, Adnan. "Biorefining of lignocellulose : Detoxification of inhibitory hydrolysates and potential utilization of residual streams for production of enzymes." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-82486.
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Lignocellulosic biomass is a renewable resource that can be utilized for the production of biofuels, chemicals, and bio-based materials. Biochemical conversion of lignocellulose to advanced biofuels, such as cellulosic ethanol, is generally performed through microbial fermentation of sugars generated by thermochemical pretreatment of the biomass followed by an enzymatic hydrolysis of the cellulose. The aims of the research presented in this thesis were to address problems associated with pretreatment by-products that inhibit microbial and enzymatic biocatalysts, and to investigate the potential of utilizing residual streams from pulp mills and biorefineries to produce hydrolytic enzymes. A novel method to detoxify lignocellulosic hydrolysates to improve the fermentability was investigated in experiments with the yeast Saccharomyces cerevisiae. The method is based on treatment of lignocellulosic slurries and hydrolysates with reducing agents, such as sodium dithionite and sodium sulfite. The effects of treatment with sodium borohydride were also investigated. Treatment of a hydrolysate of Norway spruce by addition of 10 mM dithionite resulted in an increase of the balanced ethanol yield from 0.03 to 0.35 g/g. Similarly, the balanced ethanol yield of a hydrolysate of sugarcane bagasse increased from 0.06 to 0.28 g/g after treatment with 10 mM dithionite. In another study with a hydrolysate of Norway spruce, addition of 34 mM borohydride increased the balanced ethanol yield from 0.02 to 0.30 g/g, while the ethanol productivity increased from 0.05 to 0.57 g/(L×h). While treatment with sulfur oxyanions had a positive effect on microbial fermentation and enzymatic hydrolysis, treatment with borohydride resulted in an improvement only for the microbial fermentation. The chemical effects of treatments of hydrolysates with sodium dithionite, sodium sulfite, and sodium borohydride were investigated using liquid chromatography-mass spectrometry (LC-MS). Treatments with dithionite and sulfite were found to rapidly sulfonate inhibitors already at room temperature and at a pH that is compatible with enzymatic hydrolysis and microbial fermentation. Treatment with borohydride reduced inhibitory compounds, but the products were less hydrophilic than the products obtained in the reactions with the sulfur oxyanions. The potential of on-site enzyme production using low-value residual streams, such as stillage, was investigated utilizing recombinant Aspergillus niger producing xylanase and cellulase. A xylanase activity of 8,400 nkat/ml and a cellulase activity of 2,700 nkat/ml were reached using stillages from processes based on waste fiber sludge. The fungus consumed a large part of the xylose, the acetic acid, and the oligosaccharides that were left in the stillages after fermentation with S. cerevisiae. In another study, the capability of two filamentous fungi (A. niger and Trichoderma reesei) and three yeasts (S. cerevisiae, Pichia pastoris, and Yarrowia lipolytica) to grow on inhibitory lignocellulosic media were compared. The results indicate that the two filamentous fungi had the best capability to utilize different nutrients in the media, while the S. cerevisiae strain exhibited the best tolerance against the inhibitors. Utilization of different nutrients would be especially important in enzyme production using residual streams, while tolerance against inhibitors is desirable in a consolidated bio-process in which the fermenting microorganism also contributes by producing enzymes.
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Belford, Ebenezer Jeremiah Durosimi. "Purification and characterization of xenobiotic detoxification enzymes in Pachyrhizus "yam bean" and their role in agrochemical metabolism." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970967012.
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Wilson, Nina Marie. "Strategies to detoxify the mycotoxin deoxynivalenol and improve food safety in the U.S." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/77928.
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Mycotoxins are toxic secondary metabolites produced by fungi that are a threat to the health of humans and domestic animals. The most important mycotoxin in the U.S. is deoxynivalenol (DON), which causes symptoms such as vomiting, feed refusal, and weight loss in farm animals. The fungus Fusarium graminearum produces DON in staple crops such as wheat, barley, and corn. It is estimated that the economic losses associated with DON contamination alone exceed $650 million per year in the U.S. New strategies are needed to mitigate DON and improve food safety in the U.S. The overall goal of my research is to discover and employ microorganisms and enzymes to detoxify DON. The specific objectives are to: (1) discover and characterize microorganisms that detoxify DON, (2) use a cell free protein synthesis (CFPS) system to study enzymes that modify DON, (3) engineer yeast to detoxify DON with a metabolic engineering strategy, and (4) deliver a high school unit to teach high school students about mycotoxins in food. In Objective 1, two mixed cultures were identified from environmental samples that converted DON into the less toxic 3-keto-deoxynivalenol (3-keto-DON). In Objective 2, a CFPS system was used to express three known acetyltransferase genes to convert DON to 3-acetyl-DON (3-A-DON). In Objective 3, we identified a potential DON transporter from a library of randomly amplified fragments from the genomes of mixed cultures of microbes isolated from the environment. In Objective 4, we developed and delivered a unique high school unit to educate high school students about potential mycotoxins in food and feed products. The work presented here represents new and improved methods for mitigating mycotoxin contamination in the United States.Ph. D.
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Lee, Sansan. "The effects of knocking down ROS detoxification enzymes on the Caenorhabditis elegans mutants clk-1(qm30) and isp-1(qm150) /." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101597.
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Caenorhabditis elegans clk-1(qm30) and isp-1(qm150) mutants exhibit highly pleiotropic phenotypes that include slow development and long lifespan. clk-1(qm30) and isp-1(qm150) correspond to loss of function mutations in genes necessary for ubiquinone biosynthesis and complex III electron transport, respectively. Previous research has lead to the hypothesis that altered levels of cellular reactive oxygen species (ROS) may underlie clk-1(qm30) and isp-1(qm150) mutant phenotypes. To test this hypothesis RNA interference (RNAi) by feeding was used to indirectly alter cellular ROS levels by knocking down genes that encode ROS detoxification enzymes. Specifically, genes that detoxify ROS using glutathione or thioredoxin, both of which are important cellular thiol-redox molecules, were knocked down to examine the role of ROS in determining clk-1(qm30) and isp-1(qm150) lifespan, post-embryonic development, and germline development. In summary, knocking down ROS detoxification genes does not severely appear to affect the phenotypes that were studied. ROS detoxification gene knockdowns consistently induced mild decreases in wild type, clk-1(qm30), and isp-1(qm150) lifespan. However, knocking down NAD+-dependent isocitrate dehydrogenases, which are not closely involved in ROS detoxification, similarly affected lifespan, indicating that decreases are not specific to ROS detoxification. Of note, knocking down gcs-1, which is required for glutathione biosynthesis, induced lethal intestinal abnormalities in wild type, c1k-1(qm30), and isp-1(qm150) worms. Overall, findings do not support that low ROS underlies the clk-1(qm30) and isp-1(qm150) mutant phenotypes.
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Davies, Warren Raymond, and warren davies@optusnet com au. "Effects of the Cyanobacterium Nodularia spumigena on Selected Estuarine Fauna." RMIT University. Applied Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080415.164533.
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Nodularia spumigena is an estuarine cyanobacteria that produces the toxin nodularin. This toxic cyanobacteria is known to have caused death to domestic and wild animals and is recognised as dangerous to human health. N. spumigena causes harmful algal blooms in many parts of the world including Australia. The toxic solutes of N. spumigena are potentially dangerous when contact is made to contaminated water bodies or is ingested by primary consumers. In Australia blooms of N. spumigena are common in the Gippsland Lakes in South-eastern Victoria and cause socio - economic hardships to the local communities. This PhD investigates the toxic effects of N. spumigena and its solutes to a range of aquatic life. A method known as SPME - HPLC showed promise in environmental monitoring of N. spumigena toxins by measuring nodularin from water samples. Other research presented study into the lethal and sublethal effects of on an extract from N. spumigena to aquatic fauna. Resu lts showed the N. spumigena extract was not lethal to many aquatic fauna although zooplankton from the Gippsland Lakes showed mortality at environmental relevant levels. Biochemical studies focusing on animal detoxification and antioxidation enzymes and DNA integrity showed sublethal effects to the N. spumigena extract. Results presented in this thesis show that an extract of N. spumigena elicited detoxification and antioxidation responses in animals tested. Furthermore, the use of the COMET assay showed increased damage to DNA of animals tested. Results also showed that different organs in animals tested responded differently to the aqueous extract, suggesting mode of uptake maybe important in toxicosis. Further, feeding studies with N. spumigena help elucidate mode of uptake using enzyme response biomarkers. The overall results of this research provided an assessment of the toxic affects of N. spumigena on aquatic fauna with special reference to the Gippsland Lakes, Victoria, Australia.
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Duca, Radu-Corneliu. "Food quality monitoring and analytical techniques optimization of some aliments within plant-animal correlation : Contaminated aliments effects on the detoxification enzymes." Paris 11, 2009. http://www.theses.fr/2009PA11T042.
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Poupardin, Rodolphe. "Interactions gènes-environnement chez les moustiques et leur impact sur la résistance aux insecticides." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00583441.
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Les moustiques génèrent une nuisance importante et sont notamment contrôlés grâce à des traitements insecticides. Aujourd'hui, les gîtes où se développent leurs larves sont souvent pollués par des xénobiotiques environnementaux (hydrocarbures, herbicides, pesticides, toxines naturelles...). Jusqu'à présent, l'impact de ces xénobiotiques sur la capacité des larves de moustiques à résister aux insecticides chimiques reste méconnu. Cette thèse vise à étudier la réponse des larves de d'Aedes aegypti aux xénobiotiques environnementaux et leur impact sur leur tolérance et résistance aux insecticides chimiques. Une première étude, sur le court terme, montre que des larves exposées pendant 24h à divers xénobiotiques deviennent plus tolérantes à vis à vis de différents insecticides chimiques (Poupardin et al. 2008). Des études biochimiques et transcriptomiques suggèrent que l'induction de certaines familles d'enzymes (e.g. P450s et GSTs) par ces xénobiotiques peut être liée à l'augmentation de tolérance des larves vis-à-vis de l'insecticide. Dans le but de mieux caractériser le profil transcriptionnel des précédents gènes candidats, des expérimentations complémentaires ont été faites à différents niveaux (Poupardin et al., 2010). Cette étude a montré que de nombreux gènes étaient préférentiellement transcrits dans des tissus fortement impliqués dans la détoxication de composés exogènes, essentiellement des CYP6. Elle révèle aussi que la transcription de ces P450s varie beaucoup au cours des différents stades de développement et qu'ils étaient induits à des faibles de doses de polluants avec un pic d'induction après 48 et 72 heures d'exposition. Ces études mettent en évidence le rôle potentiel des gènes de détoxication dans la réponse à l'exposition à des xénobiotiques et dans l'augmentation de tolérance aux insecticides chimiques. Concernant l'étude sur le long terme de l'impact des polluants sur la résistance des moustiques aux insecticides, la question est de savoir si les polluants trouvés dans l'environnement influencent la sélection de la résistance aux insecticides et si oui, favorisent-ils la sélection de gènes en particulier? Pour répondre à ces questions, trois souches d'Aedes aegypti ont été sélectionnées à la perméthrine. Ces souches sont exposées ou non à différents polluants avant sélection. Après 10 générations de sélection, des bioessais montrent une résistance de ces 3 souches vis-à-vis de la perméthrine. Aucune différence significative de niveau de résistance n'est observée entre les trois souches sélectionnées pour le moment. Pour identifier les gènes différentiellement transcrits dans ces souches, la puce "Agilent Aedes chip" développée par l'école de médecine tropicale de Liverpool (LSTM) et contenant 14200 transcrits a été utilisée. Les microarrays ont révélé que la présence de polluants ou insecticides résiduels pouvait affecter la sélection des mécanismes de résistance aux insecticides chimiques, notamment par la sélection de gènes particuliers codant pour des enzymes de détoxication (Poupardin et al, en préparation). D'une manière globale, cette thèse permettra de mieux comprendre l'impact de l'environnement chimique sur la résistance des moustiques aux insecticides et fournira de nouvelles pistes afin d'optimiser les traitements insecticides utilisés en démoustication.
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Riaz, Muhammad Asam. "Bases moléculaires de la résistance métabolique au néonicotinoïde imidaclopride chez le moustique Aedes aegypti." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENV057/document.
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Résumé trop longMosquitoes transmit several human and animal diseases and their control represents a public health challenge worldwide. In most tropical countries, efficient control of mosquitoes relies on the use of chemical insecticides targeting adults or larvae. However, resistance to the four main classes of chemical insecticides has been reported worldwide and threatens vector control programs. In this context, there is an urgent need to find alternatives to conventional insecticides used in vector control. In this thesis, I explored the potential use of the neonicotinoid insecticide imidacloprid for mosquito control, focusing on the identification of metabolic resistance mechanisms, cross-resistance with other insecticides and the impact of environmental pollutants on imidacloprid tolerance. The mosquito Aedes aegypti was used as a model species for this research work. Basal tolerance of Ae. aegypti to imidacloprid was first evaluated at the larval and adult stages. Effects of a larval exposure across a single generation to a sub-lethal dose of imidacloprid were then investigated at the toxicological and molecular levels using transcriptome profiling. Short sub-lethal exposures were also used to identify potential cross-responses between imidacloprid, other chemical insecticides and anthropogenic pollutants. Long-term adaptive response of Ae. aegypti to imidacloprid was then investigated across several generations by selecting an insecticide-susceptible strain (Bora-Bora strain) with imidacloprid at the larval stage for 14 generations in the laboratory. Such artificial selection allowed obtaining the Imida-R strain. This strain showed an increased resistance to imidacloprid in larvae while no significant resistance was measured in adults. Resistance mechanisms were then investigated using various approaches including the use of detoxification enzyme inhibitors, biochemical assays and transcriptome profiling with DNA microarray and massive mRNA sequencing. Several protein families potentially involved in resistance were identified including detoxifications enzymes and cuticle proteins. Among the formers, 8 cytochrome P450s and 1 glutathione S-transferase appears as good candidates for a role in imidacloprid metabolism. The role of P450s in the elevated resistance of the Imida-R strain was confirmed by comparative P450-dependent in vitro metabolism assays conducted on microsomal fractions of the susceptible and Imida-R strains. At the gene level, substrate binding modeling allowed restricting the panel of P450 candidates. Meantime, heterologous expression of one P450 was performed and its ability to metabolize imidacloprid confirmed. Bioassay with other insecticides revealed potential cross-resistance of the Imida-R at the larval stage to other neonicotinoids but also to an insect growth inhibitor and in a lesser extent to DDT, confirming the probable role of detoxification enzymes. Relaxing the selection pressure of the Imida-R strain for few generations led to a rapid decrease of resistance, suggesting a cost of resistance mechanisms. Comparing the inducibility of candidate detoxification genes by imidacloprid in susceptible and resistant strains revealed a higher induction of these genes in the resistant strain, suggesting the selection of both a higher constitutive expression but also a greater phenotypic plasticity of these enzymes in the Imida-R strain. Finally, the potential role of cuticle protein in resistance was preliminary investigated by exposing larvae to a chitin synthesis inhibitor before bioassays. Overall, although this research work requires additional functional validation experiments, these data provide a better understanding of imidacloprid resistance mechanisms in mosquitoes and its potential use as an alternative to conventional insecticides in vector control
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Bourret-Bernard, Claude Sophie. "Effect of lignans in associations with naturally occurring allelochemicals from the Asteraceae on the detoxification enzymes and the life cycle of a herbivorous lepidoptera, Ostrinia nubilalis, Hubner." Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/5483.
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Borentain, Patrick. "Voies de la glycosylation et carcinome hépatocellulaire." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM5047.
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La glycosylation est un processus enzymatique permettant l'ajout de sucres à des composés (sucres, lipides ou protides), modifiant ainsi leurs propriétés. La glycosylation est impliquée dans la détoxification des xénobiotiques et des variations d'activité des enzymes responsables ont été identifiées comme facteur de risque de cancer en particulier dans les organes exposés aux xénobiotiques. Dans la première partie de notre travail nous étudions l'impact des polymorphismes génétiques de certaines enzymes responsables de la détoxification (UGT1A7, GST et XRCC1) sur le risque de carcinome hépatocellulaire. Nous montrons que la combinaison de certains polymorphismes génétiques peut entraîner une augmentation du risque de CHC. Des modifications d'expression des glycoprotéines de surface ont été observées dans les cellules cancéreuses jouant un rôle dans leurs interactions avec le microenvironnement. Dans la seconde partie, nous étudions l'effet de l'inhibition des interactions des cellules de CHC/cellules endothéliales par le blocage du couple sialyl Lewis x/E-sélectine sur la croissance tumorale. Ce blocage est obtenu, d'une part par transfert du gène de la Fucosyl-transferase I, inhibant l'expression de sLex à la surface des cellules de CHC, et d'autre part, par utilisation de cimétidine ou d'amiloride permettant une inhibition de l'expression de la E-sélectine par les cellules endothéliales. Nous obtenons une inhibition de la croissance tumorale in vivo par blocage de la néoangiogénèse. Ces travaux permettent donc d'identifier des facteurs de risque génétiques de CHC et d'envisager une autre voie de traitement du CHCGlycosylation is an enzymatic process that consists of the addition of glycosyl groups to compounds (sugars, lipids or proteins), thus modifying their properties. Glycosylation is involved in the detoxification of xenobiotics and variations in activity of enzymes responsible have been identified as a potential risk factor for cancer in particular in organs in contact with the external environment. In the first part of our work we study the impact of polymorphisms of detoxification enzyme (UGT1A7, GST and XRCC1) on the risk of hepatocellular carcinoma. We show that the combination of genetic polymorphisms of such enzymes may increase the risk of HCC. Modifications in the expression of surface glycoproteins have been observed in cancer cells and play a role in their interactions with the tumoral microenvironment. In the second part, we study the effect of inhibition of interactions of HCC cells / endothelial cells on tumor growth by blocking the interaction between sialyl Lewis x and E-selectin. First, we achieved the inhibition of the expression of sLex on the surface of HCC cells by introducing fucosyl transferase- I gene in HCC cells. In a second part of our work we used cimetidine and amiloride to inhibit the expression of E-selectin by endothelial cells. This approach resulted in inhibition of HCC cells / endothelial cells interaction and thereby tumor growth inhibition in vivo. This effect is mediated by an inhibition of tumor neoangiogenesis. This work therefore identifies genetic risk factors for HCC and allows considering another way of treatment of HCC
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Rabêlo, Flávio Henrique Silveira. "Sulfur supply as a sustainable technology for phytoextraction: its effects on cadmium uptake and detoxification in Panicum maximum Jacq. cv. Massai." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/64/64133/tde-07032019-134024/.
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Cadmium (Cd) concentration in the environment has increased in most recent decades, which represents a serious socio-environmental problem, since Cd is toxic to most living beings. Thus, it is important to reduce the concentration of this metal in contaminated environments, and the use of plants properly supplied with sulfur (S) can contribute to this (phytoextraction), since S is a component of metabolites involved in defense responses against stress caused by Cd. Therefore, our aim with this study was to evaluate the effect of S on i) Cd uptake kinetics, ii) root development and nutrient uptake, iii) metabolic profiling and thiol peptides synthesis, and iv) activity of antioxidant and photosynthetic system of Massai grass (Panicum maximum Jacq. cv. Massai) used for Cd phytoextraction. The studies were carried out in a greenhouse conditions using pots of 0.5 and 2.0 L for development of the study about Cd uptake kinetics (treatments represented by combinations of S: 0.1 and 1.9 mmol L-1 and Cd concentrations: 0.1 and 0.5 mmol L-1) and Cd detoxification mechanisms (treatments represented by combinations of S: 0.1, 1.9 and 3.7 mmol L-1 and Cd concentrations: 0.0, 0.1 and 0.5 mmol L-1), respectively. Pots were distributed in randomized blocks, with four replications. Plants used in Cd kinetics study were exposed to treatments for 14 days after they remained in solutions containing only S for 42 days, while plants used in Cd detoxification study were exposed to treatments for 9 days after growing in solutions containing only S for 44 days. At the end of studies, plants used were harvested and sent for analysis. Maximum uptake rate (Vmax) and Cd apoplastic influx of Massai grass exposed to highest Cd concentration was highest when the plants were supplied with highest S concentration. The root development of Massai grass was strongly inhibited when plants were exposed to 0.5 mmol L-1 Cd, but proper (1.9 mmol L-1) S supply allowed highest Cd uptake, while excessive S supply (3.7 mmol L-1) decreased iron plaques formation in the roots of plants. Lysine, cysteine, ornithine, arginine, tryptophan and histidine were accumulated in more than one tissue in plants exposed to Cd, as well as galactinol. Glutathione (GSH), phytochelatins (PCs) and their homologues were strongly induced by Cd, whereas plants supplied with 1.9 and/or 3.7 mmol L-1 S showed the highest concentrations of these peptides. Plants supplied with highest S concentration showed lowest lipid peroxidation and highest photosynthetic rate, which evidences that antioxidant system of these plants was more efficient in mitigating the damages caused by Cd. In view of these results, it is clear that Massai grass properly supplied with S shows greatest Cd tolerance, as well as phytoextraction potentialA concentração de cádmio (Cd) no ambiente aumentou em décadas recentes, o que representa sério problema sócio-ambiental, visto que o Cd é tóxico para a maioria dos seres vivos. Por isso, é importante reduzir a concentração desse metal em ambientes contaminados e o uso de plantas adequadamente supridas com enxofre (S) pode contribuir para isso (fitoextração), uma vez que o S é componente de metabólitos envolvidos no combate ao estresse causado pelo Cd. Assim, o nosso objetivo com esse estudo foi avaliar o efeito do S na i) cinética de absorção do Cd, no ii) desenvolvimento radicular e na absorção de nutrientes, no iii) perfil metabólico e síntese de compostos tiol, e iv) na atividade do sistema antioxidante e fotossintético do capim-massai (Panicum maximum Jacq. cv. Massai), utilizado para fitoextração de Cd. Os estudos foram conduzidos em casa de vegetação utilizando-se vasos de 0,5 e 2,0 L para a condução do estudo de cinética de absorção de Cd (tratamentos representados pelas combinações das doses de S de 0,1 e 1,9 mmol L-1 e Cd de 0,1 e 0,5 mmol L-1) e para o estudo dos mecanismos de detoxificação de Cd (tratamentos representados pelas combinações das doses de S de 0,1; 1,9 e 3,7 mmol L-1 e Cd de 0,0; 0,1 e 0,5 mmol L-1), respectivamente. Os vasos foram distribuídos em blocos ao acaso, com quatro repetições. As plantas utilizadas no estudo de cinética foram expostas aos tratamentos durante 14 dias após as mesmas terem permanecido em soluções contendo apenas S durante 42 dias, enquanto as plantas utilizadas no estudo de detoxificação de Cd foram expostas aos tratamentos pelo período de 9 dias após terem crescido em soluções contendo apenas S por 44 dias. Ao final dos estudos, as plantas utilizadas foram colhidas e encaminhadas para análises. A velocidade máxima de absorção (Vmax) e o influxo apoplástico de Cd do capim-massai exposto à maior dose de Cd foram maiores quando as plantas foram supridas com a maior dose de S. O desenvolvimento radicular do capim-massai foi fortemente inibido quando as plantas foram expostas à dose de Cd de 0,5 mmol L-1, mas o adequado (1,9 mmol L-1) suprimento de S permitiu maior absorção de Cd, enquanto o suprimento excessivo (3,7 mmol L-1) de S diminuiu a formação de placas de ferro nas raízes das plantas. A lisina, cisteína, ornitina, arginina, triptofano e histidina foram acumulados em mais de um tecido nas plantas expostas ao Cd, assim como o galactinol. A glutationa (GSH), as fitoquelatinas (PCs) e seus homólogos foram fortemente induzidos pelo Cd, sendo que as plantas supridas com as doses de S de 1,9 e/ou 3,7 mmol L-1 apresentaram as maiores concentrações desses peptídeos. As plantas supridas com as maiores doses de S apresentaram menor peroxidação lipídica e maior taxa fotossintética, o que demonstra que o sistema antioxidante dessas plantas foi mais eficiente na atenuação dos danos causados pelo Cd. Diante desses resultados, fica claro que o capim-massai suprido adequadamente com S apresenta maior tolerância ao Cd, assim como maior potencial de fitoextração
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Nascimento, Antonio Rogério Bezerra do. "Bases genéticas e moleculares da resistência de Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) a lufenuron." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/11/11146/tde-04022014-095258/.
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As bases genéticas e moleculares da resistência de Spodoptera frugiperda (J.E. Smith) a lufenuron foram exploradas no presente estudo. Inicialmente, uma linhagem de S. frugiperda resistente a lufenuron foi selecionada a partir de uma população coletada na cultura do milho na região de Montevidiu-GO com intenso uso desse inseticida. As curvas de concentração-resposta a lufenuron para as linhagens de S. frugiperda suscetível (SUS) e resistente (LUF-R) a lufenuron foram caracterizadas pelo método de bioensaio com tratamento superficial da dieta artificial. As CL50 (I.C. 95%) estimadas para as linhagens SUS e LUF-R foram de 0,23 (0,18 - 0,28) e 210,6 (175,90 - 258,10) ?g de lufenuron.mL-1 respectivamente, com razão de resistência de ? 915 vezes. A partir dos resultados de cruzamentos recíprocos entre as linhagens SUS e LUF-R, concluiu-se que a herança da resistência de S. frugiperda a lufenuron é autossômica e incompletamente recessiva. Os testes de retrocruzamentos da progênie F1 de cruzamentos recíprocos com o parental LUF-R demonstraram um efeito poligênico para a resistência, com a estimativa do número mínimo de segregações independentes entre 1,54 e 1,71, indicando que o número de loci associado à resistência é baixo. Para conhecer o perfil de transcritos de lagartas de S. frugiperda e avaliar o padrão de expressão gênica diferencial entre lagartas da linhagem LUF-R em comparação ao de lagartas da linhagem SUS, buscando identificar o(s) mecanismo(s) de resistência a lufenuron, foram utilizadas novas tecnologias de sequenciamento em larga escala. Para isso, foram utilizados sequenciamentos de quatro bibliotecas de cDNA (plataforma HiScan 1000, Illumina©) obtidas de lagartas de 4º ínstar de S. frugiperda das linhagens LUF-R e SUS, induzidas ou não com lufenuron. O transcritoma foi construído utilizando aproximadamente 19,6 milhões de leituras single-end, o que gerou 18.506 transcritos, com N50 de 996 pb. A pesquisa contra o banco de dados nr (NCBI) proporcionou anotação funcional de 51,1% (9.457) dos transcritos obtidos, grande parte dos alinhamentos apresentaram homologia a insetos, com o maior número deles (45%) se assemelhando aos de Bombyx mori (Lepidoptera: Bombycidae), enquanto 10% se assemelharam a sequências de diversas espécies do gênero Spodoptera (Lepidoptera: Noctuidae), sendo 3% dos alinhamentos obtidos contra sequências de Spodoptera frugiperda. A análise comparativa da expressão gênica entre lagartas de S. frugiperda resistente e suscetível a lufenuron identificou 1.224 transcritos expressos diferencialmente (p <= 0,05, teste t; expressão relativa > 2). Sete destes transcritos foram associados ao metabolismo da cutícula, sendo cinco deles superexpressos na linhagem LUFR. O metabolismo de detoxificação apresentou 48 transcritos expressos diferencialmente, dos quais foram identificados 40 transcritos associados às monooxigenases P450, cinco a glutationa-S-transferase, dois às carboxilesterases e um a esterase. Foi observado que 39 dos 48 transcritos associados ao metabolismo de detoxificação foram superexpressos na linhagem resistente. Este padrão foi confirmado a partir da expressão relativa utilizando \"PCR quantitativa em Tempo Real - qPCR\". Estes resultados representam um importante passo para o entendimento dos mecanismos moleculares da resistência de S. frugiperda a lufenuron, proporcionando, ainda, uma visão mais ampla do perfil de expressão gênica de insetos a inseticidas.The genetic and molecular basis of resistance to lufenuron in Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) were exploited in this study. The resistant population of S. frugiperda was selected from a population collected in Montevidiu, Goiás. Initially, a luferunon-resistant strain of S. frugiperda was selected from a population collected in cornfields located in Montevidiu, Goiás State, Brazil, with intense use of this insecticide. The diet surface treatment bioassay was used to characterize the concentration-response to lufenuron in the susceptible (SUS) and resistant (LUF-R) strains of S. frugiperda. The estimated LC50s (95% C.I.) for the SUS and LUF-R strains were 0.23 (0.18 - 0.28) and 210.6 (175.90 - 258.10) ?g of lufenuron.mL-1 respectively, with resistance ratio of ? 915-fold. Based on reciprocal crosses between SUS and LUF-R strains, the inheritance of S. frugiperda resistance to lufenuron was incomplete autosomal recessive. Backcrosses between F1 of the reciprocal crosses and the parental LUF-R revealed a polygenic resistance, with an estimation of the minimum number of resistance genes from 1.54 to 1.71, indicating that the number of loci associated to resistance is low. Then, a new high-throughput cDNA sequencing technologies was explored to characterize the transcriptional profile of larvae of Spodoptera frugiperda, and to compare the differential gene expression between resistant and susceptible strains of S. frugiperda to lufenuron in order to identify the resistance mechanism(s) involved. Four cDNA libraries obtained from fourth instars of the resistant (LUF-R) and the susceptible (SUS) S. frugiperda strains, exposed or not to lufenuron, were sequenced in a HiScan1000® platform (Illumina©). The transcriptome was de novo assembled using nearly 19.6 million single-end reads, leading to 18,506 transcripts with a N50 of 996 bp in length. A Blast search against the non-redundant database available in NCBI allowed the functional annotation of 51.1% (9,457) of the obtained transcripts. Most of these transcripts aligned with insect sequences, and a majority of them (45%) with Bombyx mori (Lepidoptera: Bombycidae). Nearly 10% of the transcripts aligned with species belonging to Spodoptera (Lepidoptera: Noctuidae), with 3% of the alignments matching sequences from Spodoptera frugiperda. Differential gene expression analysis between the resistant and the susceptible strains identified 1,224 differentially expressed transcripts (p <= 0.05, t-test; fold change > 2). Seven of them were associated with the cuticle metabolism, and five out seven were up-regulated in the resistant strain (LUF-R). A large set of transcripts (48) associated with the detoxification metabolism was differentially expressed; 40 P450 monooxygenases, five glutathione-Stransferases, two carboxylesterase and one esterase were identified. Thirty-nine out of these 48 transcripts were up-regulated in the resistant strain. Gene expression data obtained by RNA-Seq analysis was validated by quantitative real time PCR (qPCR) of several selected target transcripts. These results represent an important step toward the understanding of the molecular mechanisms of resistance of S. frugiperda to lufenuron, and provide a broader view on the gene expression profile of insects to insecticides.
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Marakalala, Mohlopheni Jackson. "Inhibition of a Mycothiol biosynthetic enzyme and a detoxification enzyme as anti-tubercular drug targets." Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/2694.
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Hou, Shurong. "HUMAN BUTYRYLCHOLINESTERASE MUTANTS FOR COCAINE DETOXIFICATION." UKnowledge, 2014. http://uknowledge.uky.edu/pharmacy_etds/38.
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Cocaine is one of the most reinforcing drugs of abuse and has caused serious medical and social problems. There is no FDA-approved medication specific for cocaine. It is of a high priority to develop an effective therapeutic treatment for cocaine abuse. Human butyrylcholinesterase (BChE) has been recognized as a promising candidate of enzyme therapy to metabolize cocaine into biologically inactive metabolites and prevent it from reaching central nervous system (CNS). However, the catalytic activity of wide-type human BChE against cocaine is not sufficiently high for treatment of cocaine abuse. Dr. Zhan’s lab has successfully designed and discovered a series of high-activity mutants of human BChE specific for cocaine metabolism.
This dissertation is mainly focused to address the possible concerns in further development of promising human BChE mutants for cocaine detoxification, including whether the administration of this exogenous enzyme will affect the cholinergic system, whether it can efficiently hydrolyze cocaine’s toxic metabolites, and whether the commonly used therapeutic agents will significantly affect the catalytic activity of the BChE mutants against cocaine when they are co-administered. According to the results obtained, all of the examined BChE mutants have a considerably improved catalytic efficiency against (-)-cocaine, without significantly improving the catalytic efficiency against any of the other examined substrates, including neurotransmitter acetylcholine. Two representative mutants (including E12-7) also have a considerably improved catalytic activity against cocaethylene (formed from combined use of cocaine and alcohol) compared to wild-type BChE, and E12-7 can rapidly metabolize cocaethylene, in addition to cocaine, in rats. Further evaluation of possible drug-drug interactions between E12-7 and some other commonly used therapeutic agents revealed that all of the examined agents, except some tricyclic antidepressants, do not significantly inhibit E12-7. In addition, an effort to discover new mutants with further improved activity against cocaine led to the discovery of a new BChE mutant, denoted as E20-7, according to both the in vitro and in vivo assays. The encouraging outcomes of the present investigation suggest that it is possible to develop a more effective enzyme therapy for cocaine abuse treatment using one of the most promising BChE mutants, such as E12-7 or E20-7.
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Kern, Rory James. "Enzyme-based detoxification of organophosphorus neurotoxic pesticides and chemical warfare agents." Thesis, [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2118.
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Wagner, Catherine Ann Robertson. "Reproduction and Enzyme Detoxification Activities in Mouse Lines Selected for Response to Fescue Toxicosis." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/9783.
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In previous work, mouse lines were selected for resistance (R) or for susceptibility (S) to fescue toxicosis based upon reductions in post-weaning growth rate caused by an endophyte-infected diet. The first objective of the current experiment was to determine whether long term reproduction of S mice was more severely depressed than that of R mice by the toxic diet. The second objective was to quantify glutathione-S-epoxytransferase (GST) and uridine diphosphate glucuronosyl-transferase (UDPGT) activities in R and S dams form the experiment and to determine whether reproduction during continuous cohabitation and liver detoxification enzyme activities were correlated within line x diet groups. Effects of the toxic diet were detectable within the first litters produced. Reproduction was more seriously influenced by the toxic diet within the S line than within the R line when these measures were compared within four equal time phases. The effects of the toxic diet on reproduction were greatest early in the experiment; by the fourth time phase differences among line x diet groups, with the exception of litter weight, were not significant. Percentage differences in total reproduction were greater between S mice fed the non-toxic diet and S mice fed the toxic diet than those between the R mice fed the non-toxic and toxic diets. Averaged across diets, GST activities were higher in R mice, but UDPGT activities were not significant. Within R line mice, GST was correlated with three reproductive measures, but UDPGT activity was not correlated with reproduction within any line x diet group.Master of Science
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Liu, Su Qi. "The Activity of Analogs of the Natural Product Dillapiol and Sessamol as Detoxification Enzyme Inhibitors and Insecticide Synergists." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32997.
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In the present thesis, analogs of the plant derived compound, dillapiol, were investigated for their potential as cytochrome P450 inhibitors and insecticide synergists. Dillapiol was chosen as a lead compound because it has a methylenedioxyphenyl (MDP) functionality that serves as a cytochrome P450 inhibitor and reported insecticide synergist activity comparable to the commercially used piperonyl butoxide (PBO). Initially a set of fifty two dillapiol analogs was investigated for inhibition of cytochrome P450 using cloned Human CYP3A4, a highly standardized preparation that allowed accurate determination of structure activity relationships. A qualitative analysis revealed that analogs with a large acyl group attached via ester bonds had higher in vitroCYP3A4 inhibitory activity. However, a Gaussian Quantitative Structure Activity Relationship model also showed the importance of hydrophobic interactions and predicted new structures with higher P4503A4 inhibition. Subsequently selected analogs were investigated as potential pyrethrum synergists in insecticide susceptible (SS-CPB) and resistant (RS-CPB) Colorado potato beetle (Leptinotarsadecemlineata Say) (Coleoptera: Chrysomelidae) as well as the European corn borer (ECB, Ostrinia nubilalis Hübner). Using discriminating dose and full concentration bioassays, the synergistic activity of selected analogs was studied. Ether analogs demonstrated stronger synergistic activity than ester analogs for both insect species. All tested compounds displayed higher synergistic activity by ingestion than topical administration, and each analog type (ester and ether) had one compound with a synergism ratio greater than 20. Both compounds successfully restored the insecticide susceptibility within RS-CPB resistant strain larvae to pyrethrum. In greenhouse and field trials, pyrethrum extract combined with dillapiol was effective against SS-CPB, and the pyrethrum + dillapiol formulation demonstrated efficacy at least 10 times higher than that of pyrethrum alone. This suggested the feasibility of dillapiol as a novel PBO replacement for organic farming. The intrinsic toxicity of the most active analogs compared to dillapiol or PBO were determined by growth inhibition bioassay with ECB larvae which were administrated a synergist treated diet. In several growth parameters of ECB evaluated, PBO was found to have the strongest intrinsic toxicity, followed by the ester analog. Dillapiol showed the least toxicity among four tested compounds, while the ether analog, which was the best pyrethrum synergist against both oligophagous CPB and polyphagous ECB, had a similar safety level compared todillapiol.T o explore the underlying mechanism of the synergists, the impact of selected compounds on three major detoxification enzymes, monooxygenase P450, Gluthatione S-transferases (GST) and esterases of both insect species were evaluated. All selected analogs effectively inhibited in vitro and in vivoP450 monooxygenases activity for both oligophagous CPB and polyphagous ECB. The best pyrethrum synergist also displayed significantly greater P450 inhibitory activity than PBO which was eleven times more effective than PBO as an inhibitor of ECB in vitroP450 activity. The inhibition assay with either CPB or ECB GSTs respectively produced the surprising result that the best pyrethrum synergist exhibited a 180-fold or 575-fold lower IC50than the standard inhibitor of GST. To our knowledge, this is the first report of MDP related compounds showing significant GST inhibitory activity. A pilot study of insect dysregulation induced by synergists was conducted with Ultra Performance Liquid Chromotagraphy (UPLC)-Quadrupole Time of Flight Mass Spectrometry (QTOF/MS). It was found to be a suitable technique to study the metabolites changes induced by selected analogs for the two insect species. The application of UPLC-QTOF/MS produced high-resolution metabolites profiles which guarantees the success of the dynamic metabolism research of selected insects in the future.
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Worrall, Stephen Frederick. "An investigation into the association between cytochrome P450 and glutathione S-transferase detoxification enzyme polymorphisms and human oral squamous cell carcinoma." Thesis, University of Birmingham, 1998. http://etheses.bham.ac.uk//id/eprint/31/.
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Oral squamous cell carcinoma is the sixth commonest cancer in the world. Most patients who develop oral cancer are elderly males who are heavy users of tobacco and alcohol although the incidence is increasing in younger individuals and in those who neither smoke nor drink. Approximately 80% of human cancers result from exposure to xenobiotics. Over the millennia Man has evolved complex families of detoxification enzymes to metabolise and eliminate these harmful compounds. Many of the genes that code for these enzymes are polymorphic, sometimes encoding enzymes with abnormal activity profiles. Numerous diseases have been shown to be more frequent in individuals with abnormal detoxification enzyme activity. This study investigated the association between polymorphisms in cytochrome P450 and glutathione S-transferase genes and disease susceptibility in 106 patients with histologically proven squamous cell carcinoma of the oral cavity. The CYP2D6 PM phenotype was associated with a significantly increased risk of oral cancer (p = 0.0012). The CYP2D6 PM and HET phenotypes appear to be markers for a putative tumour suppressor gene at or close to 22q12. The EM phenotype is a risk factor in individuals who are heavy drinkers and smokers, possibly due to phase 1 activation of 4-(methylnitrosamino)-1-(3 pyridyl)-1-butanone.
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Grundling, Daniel Andries. "Cloning and expression of human recombinant isoform a of glycine-N-acyltransferase." Thesis, North-West University, 2012. http://hdl.handle.net/10394/9055.
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Awareness of detoxification, nowadays known as biotransformation, has become an integral part of our daily lives. It is a modern buzz word that is used to promote anything from health food to enhancement of performance in sports. Another lesser known application for detoxification is as a therapy for alleviating symptoms of inborn errors of metabolism.
Detoxification is the process where endogenous and xenobiotic metabolites are transformed to less harmful products, in the liver and kidneys, in two phases. Phase 1 detoxification includes oxidation, hydroxylation, dehydrogenation metabolic reduction and hydrolysis.
Phase 2 detoxification uses conjugation reactions to increase hydrophillicty of metabolites for excretion in bile and urine. Glycine N-acyltransferse (GLYAT; EC 2.3.1.13) is one of the amino acid conjugation enzymes. There are two variants of human GLYAT. I focused on the full-length mRNA human GLYAT isoform a, with a long term view of using it as a viable therapeutic enzyme for enhanced detoxification of harmful metabolites. I investigated if it is possible to clone and express a biologically active GLYAT. To achieve this goal I used three expression systems: traditional bacterial expression using the pET system; second generation cold shock bacterial expression using the pCOLDTF expression vector to improve solubility of the recombinant protein; and baculovirus expression in insect cells since therein some form of post translation glycosylation of the recombinant protein can occur which might improve solubility and ensure biological activity. The recombinant GLYAT expressed well in all three expression systems but was aggregated and no enzyme activity could be detected.
A denature and renature system was also used to collect aggregated recombinant GLYAT and used to try to refold the recombinant protein in appropriate refolding buffers to improve solubility and obtain biological activity. The solubility of the recombinant GLYAT was improved but it remained biologically inactive.Thesis (MSc (Biochemistry))--North-West University, Potchefstroom Campus, 2013.
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Fonseca, Casals Francina. "Pharmacogenomic study of oppioid addicts in methadone treatment / Francina Fonseca Casals." Doctoral thesis, Universitat Pompeu Fabra, 2010. http://hdl.handle.net/10803/7234.
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Although the well established efficacy of methadone maintenance treatment (MMT) in the opioid dependence disorder, there is a group of patients that are poor responders. The study of the influence of methadone pharmacodynamics and pharmacokinetics in dose requirements and program outcome remains still controversial. The aim of this dissertation is to study the pharmacodynamic and pharmacokinetic factors involved in the methadone maintenance treatment efficacy. The study recruited opioid dependence patients (DSM-IV criteria) from a MMT community program. Patients were clinically assessed and blood samples were obtained in order to evaluate methadone plasma concentrations of (R,S)-, (R) and (S)- methadone. Allelic variants of genes encoding the following proteins were assessed: BDNF, OPRM1, MYOCD, mGluR6, mGluR8, CRY1, NR4A2, 1q31.2 (rs965972), 2q21.2 (rs1867898), CYP3A5, CYP2D6, CYP2B6, CYP2C9, CYP2C19 and P-glycoprotein. Responders and non-responders were defined by means of illicit opioid consumption detected in random urinalyses.
Differences in response status were found depending on different single nucleotide polymorphisms (SNPs of genes encoding for BDNF, MYOCD and GRM6. The CYP2D6 metabolizing phenotype was associated with response to MMT, and also with methadone dosage requirement and methadone plasma concentrations.
Els programes de manteniment amb metadona (PMM) han demostrat eficàcia en el tractament del trastorn per dependència d'opiacis malgrat la persistència de pacients amb mala resposta al tractament. L'estudi dels factors farmacodinàmics i farmacocinètics implicats en la resposta terapèutica ofereix resultats controvertits. L'objectiu de la tesi doctoral que es presenta és estudiar els factors farmacodinàmics i farmacocinètics de la metadona que poden estar implicats en l'eficàcia del tractament. S'han inclòs pacients ambulatoris diagnosticats de trastorn per dependència d'opiacis (segons criteris DSM-IV) en PMM. Els pacients s'han avaluat a nivell clínic i s'han obtingut mostres de sang per a l'estudi de les concentracions plasmàtiques de (R,S)-, (R) i (S)- metadona. S'han estudiat també les variants al·lèliques dels gens que codifiquen per: BDNF, OPRM1, MYOCD, mGluR6, mGluR8, CRY1, NR4A2, 1q31.2 (rs965972), 2q21.2 (rs1867898), CYP3A5, CYP2D6, CYP2B6, CYP2C9, CYP2C19 i P-glicoproteïna. La mostra s'ha dividit en responedors i no responedors en funció del nombre de controls d'orina positius per a heroïna en analítiques realitzades de forma aleatòria.
Es van detectar diferències en resposta al tractament segons les variants dels gens codificants per a BDNF, MYOCD i GRM6. També es va detectar una associació entre el fenotip de CYP2D6, la resposta al tractament, la dosi requerida de metadona i les concentracions plasmàtiques.
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Nardini, Luisa. "Detoxification enzymes associated with insecticide resistance and exposure to entomopathogenic fungi in Anopheles arabiensis." Thesis, 2014.
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Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Health Sciences, 2013.Anopheles arabiensis is one of the major African malaria vectors, and DDT and pyrethroid resistance in this species is widespread. The aim of this study was to investigate, in detail, what detoxification enzymes are associated with insecticide resistance using the An. gambiae “detox chip”, a small-scale microarray based on genes that are putatively involved in metabolic detoxification of insecticides. The first part of the study focused on two DDT and pyrethroid resistant laboratory strains of An. arabiensis – one that originated from Sudan, and a second that originated from South Africa. One P450 was over-transcribed in the Sudanese strain, while 20 genes were over-transcribed in the South African strain. The majority of these were P450s although GSTs and redox genes were also over-transcribed. The use of synergist assays indicated that DDT and permethrin resistance were related to the presence of a kdr mutation (determined by PCR), while deltamethrin resistance was based on insecticide metabolism. In order to evaluate the role of enzymatic detoxification in permethrin resistance, a permethrin selected strain was used. No kdr mutations were present in this strain. Here, 29 genes were over-transcribed. Most of these were CYP genes (55%), followed by redox genes (21%), and GSTs (14%). A certain degree of overlap in the gene over-transcription was observed between the deltamethrin and permethrin resistant phenotypes. These genes are potentially functional against both pyrethroids, while those that differed were possibly more substrate specific. The final part of the study aimed to assess whether genes that are associated with insecticide resistance are also induced in mosquitoes infected with the entomopathogen, Beauveria bassiana. Using microarray data, a subset of important insecticide resistance genes was chosen for analysis following fungal infection. This study was based on the use of qPCR to detect changes in expression. None of the genes that were investigated were overtranscribed suggesting that virulence factors, such as toxins, produced by B. bassiana may not be inhibited by genes that are already over-expressed in insecticide resistant mosquito populations. This is promising for biological control and suggests that the fungi are viable alternatives to insecticides.
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Chen, Shu-Juan, and 陳淑娟. "Influence of host plants on insecticide tolerance and detoxification enzymes activity of spodoptera litura F." Thesis, 1985. http://ndltd.ncl.edu.tw/handle/91475137235787907383.
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Chiang, Kuan-Ying, and 姜寬盈. "Correlation Analysis of the Insecticide Resistance and Detoxification Enzymes in the Aedes aegypti (L.) Larvae." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/5z6vk6.
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碩士嘉南藥理科技大學
生物科技系曁研究所
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Field collected Aedes aegypti from each part of Tainan and Kaohsiung districts were subjected to bioassay for their susceptibilities to Temephos, Chlorpyrifos, Fenitrothion, Pirimifosmethyl, Pyrethrins, Permethrin, Fenvalerate, Cypermethrin and compared with two susceptible laboratory strains (NS strain and Bora Bora strain) by using dipping method. The resistance ratio between the 50% lethal concentration value (RR) of the field strains and the NS strain shows that the field strain were widespread, significant resistance to pyrethroid insecticides but not resistance to organophosphorus insecticides. In TPP test (insecticide-insensitive acetylcholinesterase test), the AChE residual activities of field strain compared with susceptible strain were the same in the presence of increasing concentration of propoxur. The TPP test indicate that the point mutation of acetylcholinesterase of Aedes aegypti was not found in the southern of Taiwan. Microplate assays were performed to measure levels of α-esterase, β-esterase, glutathione-S-transferase, monooxygenase enzymes. The patterns of elevate levels of detoxification enzymes in Kaohsiung districts and the Tainan districts strains were different. Comparison between bioassays and biochemical assays, the higher levels glutathione-S-transferase activity was significant correlation with the 50% lethal concentration value of pyrethroid insecticides. The effect of induction detoxification enzymes activity by exposure of Aedes aegypti larvae to sub-lethal dose of permethrin was investigated. The induction detoxification enzymes activity by permethrin in the 97 Tainan East district strain were significant higher than NS strain. The induction effect was no consistency between the experimental field strains in the 1 hr, sub-lethal dose exposure treatment. The mechanisms of insecticide resistance need to be clarified and explored further.
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LIU, SHU-XUAN, and 劉淑萱. "The studies of the insecticide susceptibility and the detoxification enzymes of apis cerana and apis mellifera." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/06106814166858789808.
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Thornton, Benjamin J. "Sex-dependent changes in activity of detoxification enzymes, insecticide susceptibility, and alterations in protein expression induced by atrazine in Drosophila melanogaster." 2009. http://proquest.umi.com/pqdweb?did=1816596021&sid=3&Fmt=2&clientId=14215&RQT=309&VName=PQD.
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Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009.Title from title screen (site viewed January 12, 2010). PDF text: v, 131 p. : ill. ; 3 Mb. UMI publication number: AAT 3360086. Includes bibliographical references. Also available in microfilm and microfiche formats.
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Belford, Ebenezer Jeremiah Durosimi [Verfasser]. "Purification and characterization of xenobiotic detoxification enzymes in Pachyrhizus "yam bean" and their role in agrochemical metabolism / Ebenezer Jeremiah Durosimi Belford." 2004. http://d-nb.info/970967012/34.
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Ko, Ya-Ling, and 柯雅羚. "The ethanolic extracts of coriandrum sativum up-regulate the expression of phase II detoxification enzymes and heme oxygenase 1（HO-1）expression in rat clone 9 liver cells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/03769077197257195766.
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碩士中山醫學大學
營養學研究所
101
Coriandrum sativum belongs to the family Apiaceae widely used in Mediterranean, Middle estern and Southeast Asia as spices and herbal medicine. Coriandrum sativum is rich in phenolic compounds wich have been report to lessen inflammation and oxidative stress. Our previous studies demonstrated the anti-inflammatory property of Coriandrum sativum. Here we examined the effect of Coriandrum sativum ethanol extract on expression of phase II detoxification enzymes and heme oxygenase 1 (HO-1) in rat clone 9 liver cells. Coriandrum sativum ethanol extract singnificantly induced HO-1, pi class of glutathione S-transferase (GSTP) and NAD(P)H: quinone oxidoreductase 1 (NQO1) protein and mRNA expression and enzyme activities. Furthermore Coriandrum sativum ethanol extract increased phosphorylation of p38 mitogen-activated protein kinase (p38) and nuclear factor erythroid 2 related factor 2 (Nrf-2) nuclear translocation, Nrf-2 nuclear protein DNA binding activity, as well as antioxidant response receptor (ARE) -luciferase activity and GSTP promoter activity. Pretreatment with SB203580, p38 inhibitor, blocked p38 activation as well as HO-1, GSTP and NQO-1 protein expression induced by Coriandrum sativum ethanol extract. Moreover, silencing of Nrf2 expression by shRNA gene knockdown only inhibiting Coriandrum sativum ethanol extract-induced GSTP and NQO-1 protein expression but not HO-1. These results suggested that Coriandrum sativum up-regulated expression of GSTP and NQO-1 through the p38 and Nrf2/ARE pathway.
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Selvi, A. Tamil. "Metallo-β-Lactamase, Phosphotriesterase And Their Functional Mimics." Thesis, 2009. http://hdl.handle.net/2005/994.
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Metallohydrolases with dinuclear-zinc active sites perform many important biological hydrolytic reactions on a variety of substrates. In this regard, metallo-β-lactamases (mβ1, class B) represent a unique subset of zine hydrolases that hydrolyze the β-lactam ring in several antibiotics. The antibiotic resistance that results from this hydrolysis is becoming an increased threat for the clinical community. These metalloenzymes can hydrolyze a wide range of β-lactam substrates, such as cephamycins and imipenem that are generally resistant t the serine-containing β-lactamases. Therefore, the clinical application of the entire range of antibiotics is severely compromised in bacteria that produce mβls. Due to the lack of information on the mechanism of mβls, to-date, no clinically known inhibitors is there for mβls. In this present study, we synthesized several mono and dizinc complexes as models for the mβls and investigated the differences in their hydrolytic properties. This study supports the assumption that the second zinc in the dinuclear enzymes does not directly involve in the catalysis, but may orient the substrates for hydrolysis and the basic amino acid residues such as Asp and His may activate the zinc-bound water molecules, fulfilling the role of the second zinc in the mononuclear enzymes.
The effect of various side chains on the hydrolysis of some commonly used cephalosporin antibiotics by mβl from B.cereus is described. It is shown that the cephalosporins having heterocyclic thiol side chains are more resistance to mβl-mediated hydrolysis than the antibiotics that do not have such side chains. This is partly due to the inhibition of enzyme activity by the thiol moieties eliminated during the hydrolysis. It is also observed that the heterocyclic side chains in pure form inhibit the lactamase activity of mβl as well as its synthetic mimics. The mode of binding of these heterocyclic side chains to the zinc has been analyzed from the crystal structure of the tetranuclear zinc complexes. The theoretical studies suggest that the eliminated heterocyclic thiols undergo a rapid tautomerism to produce the corresponding thiones. These thiones are found to irreversibly inhibit the LPO-catalyzed iodination reaction. The reaction of various thiones with I2 leads to the formation of thione-iodine complexes similar to that of the most commonly used antithyroid drug methimazole(MMI). These observations suggest that some of the latest generation of antibiotics may show negative effects on thyroid gland upon hydrolysis.
Synthetic organophosphorus compounds have been used extensively as pesticides and petroleum additives. These compounds are very toxic to mammals and their widespread use in agriculture leads to serious environmental problems. Therfore, degradation of organophosphorus trimesters and remediation of associated contaminated sites are of worldwide concern. In this regards, the bacterial phsophotriesterase (PTE) enzyme plays an important role in degrading a wide range of organophosphorus esters and the active side of PTE has been shown to be very similar to that of mβl. This identification prompted us to check the hydrolysis of phosphotriesters by the mβl and its mimics. It has been observed that the dinuclear zine(II) complexes that do not allow a strong binding of phosphodiestes would be a better PTE mimics.
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Gowri, V. S. "Analysis Of Protein Evolution And Its Implications In Remote Homology Detection And Function Recognition." Thesis, 2007. http://hdl.handle.net/2005/568.
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One of the major outcomes of a genome sequencing project is the availability of amino acid sequences of all the proteins encoded in the genome of the organism concerned. However, most commonly, for a substantial proportion of the proteins encoded in the genome no information in function is available either from experimental studies or by inference on the basis of homology with a protein of known function. Even if the general function of a protein is known, the region of the protein corresponding to the function might be a domain and there may be additional regions of considerable length in the protein with no known function. In such cases the information on function is incomplete.
Lack of understanding of the repertoire of functions of proteins encoded in the genome limits the utility of the genomic data. While there are many experimental approaches available for deciphering functions of proteins at the genomic scale, bioinformatics approaches form a good early step in obtaining clues about functions of proteins at the genomic scale (Koonin et al, 1998). One of the common bioinformatics approaches is recognition of function by homology (Bork et al, 1994). If the evolutionary relationship between two proteins, one with known function and the other with unknown function, could be established it raises the possibility of common function and 3-D structure for these proteins(Bork and Gibson, 1996). While this approach is effective its utility is limited by the ability of the bioinformatics approach to identify related proteins when their evolutionary divergence is high leading to low amino acid sequence similarity which is typical of two unrelated proteins (Bork and Koonin, 1998). Use of 3-D structural information, obtained by predictive methods such as fold recognition, has offered approaches towards increasing the sensitivity of remote homology detection 9e.g., Kelley et al, 2000; Shi et al, 2001; Gough et al, 2001).
The work embodied in this thesis has the general objective of analysis of evolution of structural features and functions of families of proteins and design of new bioinformatics approaches for recognizing distantly related proteins and their applications. After an introductory chapter, a few chapters report analysis of functional and structural features of homologous protein domains. Further chapters report development and assessment of new remote homology detection approaches and applications to the proteins encoded in two protozoan organisms. A further chapter is presented on the analysis of proteins involved in methylglyoxal detoxification pathways in kinetoplastid organisms.
Chapter I of the thesis presents a brief introduction, based on the information available in the literature, to protein structures, classification, methods for structure comparison, popular methods for remote homology detection and homology-based methods for function annotation.
Chapter 2 describes the steps involved in the update and improvements made in this database. In addition to the update, the domain structural families are integrated with the homologous sequences from the sequence databases. Thus, every family in PALI is enriched with a substantial volume of sequence information from proteins with no known structural information.
Chapter 3 reports investigations on the inter-relationships between sequence, structure and functions of closely-related homologous enzyme domain families.
Chapter 4 describes the investigations on the unusual differences in the lengths of closely-related homologous protein domains, accommodation of additional lengths in protein 3-D structures and their functional implications.
Chapter 5 reports the development and assessment of a new approach for remote homology detection using dynamic multiple profiles of homologous protein domain families.
Chapter 6 describes development of another remote homology detection approach which are multiple, static profiles generated using the bonafide members of the family. A rigorous assessment of the approach and strategies for improving the detection of distant homologues using the multiple profile approach are discussed in this chapter.
Chapter 7 describes results of searches made in the database of multiple family profiles (MulPSSM database) in order to recognize the functions of hypothetical proteins encoded in two parasitic protozoa.
Chapter 8 describes the sequence and structural analyses of two glyoxalase pathway proteins from the kinetoplastid organism Leishmania donovani which causes Leishmaniases. An alternate enzyme, which would probably substitute the glyoxalase pathway enzymes in certain kinetoplastid organisms which lack the glyoxalase enzymes are also discussed.
Chapter 9 summarises the important findings from the various analyses discussed in this thesis.
Appendix describes an analysis on the correlation between a measure of hydrophobicity of amino acid residues aligned in a multiple sequence alignment and residue depth in 3-D structures of proteins.
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張大惠. "Screening, cultivation & enzyme assays of detoxification potential fungi." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/26671949994005901325.
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Wan-Chi and 廖婉琦. "Effect of piper betle leaf on gene expression of detoxification enzyme in liver." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/2r6eb8.
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碩士中山醫學大學
生化暨生物科技研究所
100
Liver is an important organs involved in many physiological roles. Recent research indicates that water extracts of piper betel leaf (PBL) have antioxidant effect. PBL decreased the AST, ALT, and increased SOD, CAT enzyme activities to decrease free radicals induced by CCl4 in rat liver. This effect was elicited via the Ras/Raf signal pathway and induction of TIMP2 to active MMP2 enzyme expression that might enhance the degradation of α-sma, and to ease liver fibrosis. To further understand the hepatoprotective effect of the PBLs, this study use the AAF-induced liver damage model to examine the influence of PBL on the expression of liver detoxification enzymes. Animals were pretreated with PBLs before the induction of AAF, and then PBLs and AAF were given simultaneously. At the end of the study RT-PCR was used to determine the mRNA expression of detoxification enzymes in rat liver that was further correlated to the biochemical markers in sera. The results showed that PBLs alone did not affect liver function. However, AAF influenced the levels of 13 genes in which CYP1A1, GSTM5, and GSTP1 were increased and the rest were decreased. The correlation analysis of the normal group showed that the P450 activity, lymphocyte and platelet were negatively correlated, and became positively correlated in the AAF-induction group. The AAF combined with PBLs group found dose-dependent increases in hepatic nodular lesions and deterioration. However, the combined treatment of PBL did not change the gene expression of AAF, except CYP1A1、CYP2B3、CYP2E1、CYP3A23/3A1. The results show that PBLs did not affect the expression of the detoxification enzymes, indicating that the protective role of PBL may not be through the detoxification metabolic pathway. However, we can not rule out the possibility that the long-term feeding of this study might diminish the immediate impact of betel leaf.
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Kaplan, Warren H. "The conformational stability of a detoxification enzyme widely used as a fusion-protein affinity tag." Thesis, 1997. https://hdl.handle.net/10539/26092.
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A thesis submitted to the Faculty of Science, University of the Witwatersrand, in
fulfilment of the requirements for the degree of Doctor of Philosophy.A glutathione S-transferase (Sj26GST) from Schistosoma japonicum, which functions in the parasite's Phase II detoxification pathway, is expressed by the Pharmacia pGEX-2T plasmid and is widely used as a fusion-protein affinity tag. It contains all 217 residues of Sj26GST and an ad titional 9-residue peptide linker with a thrombin cleavage site at its C-terminus. Size-exclusion HPLC (SEC-HPLC) and SDS-PAGE studies indicate that purification of the homodimeric protein under nonreducing conditions results in the reversible for-ration of significant amounts of 160 -kDa and larger aggregates without a loss in catalytic activity. The basis for oxidative aggregation can be ascribed to the high degree of exposure of the four cysteine residues per subunit. The conformational stability of the dimeric protein was studied by urea- and temperature-induced unfolding techniques. Fluorescence-spectroscopy, SEC-HPLC, urea- and temperature-gradient gel electrophoresis, ultraviolet melting, differential scanning micro calorimetry , and enzyme activity were employed to monitor structural and functional changes. The unfolding data indicate the absence of thermodynamically stable intermediates and that the umolding/refolding transition is a two-state process involving folded native dimer and unfolded monomer. The stability of the protein was found to be dependent on its concentration with a ~GO(H20) = 26 ±1.7 kcal/mol. The conformational stability was unchanged in the presence of the leading antischistosomal drug Praziquantel, which bound the protein with a Kd = 9 ±1.8 p,M. The strong relationship observed between the m-v,llue and the size of the protein indicates that the amount of protem. surface exposed to solvent upon unfolding is the major structural de.erminant for the dependence of the protein's free energy of unfolding on urea concentration. 'Ihermograms obtained by differential scanning calorimetry also fitted to a two-state irreversible unfolding transition, both in the presence and absence of Praziquantel, with values of ~Cp = 1779 cal mol-IK-I , ~HcaI = 227 kcal/mol, AHVH ::::::233 kcal/mol (r :::::~:HVHIAlIcal = 1.02) and AS = 354 cal mol''K". The low ~Cp and ~S, when compared with the theoretically determined values, implied that the thermal denaturation of Sj26GST did not result in complete unfolding of the protein,
Andrew Chakane 2018
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Van, der Sluis Rencia. "Investigation and characterisation of the genetic variation in the coding region of the glycine N-acyltransferase gene / Rencia van der Sluis." Thesis, 2015. http://hdl.handle.net/10394/15639.
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Thorough investigation of the glycine conjugation pathway has been neglected over the last 30 years. Environmental factors, nutrition, and the chronic use of medications are increasing the exposure of humans to benzoate and drugs that are metabolized to acyl-CoA intermediates. Glycine conjugation of mitochondrial acyl-CoAs, catalysed by glycine N-acyltransferase (GLYAT, E.C. 2.3.1.13), is an important metabolic pathway responsible for maintaining adequate levels of free coenzyme A (CoASH). However, because of the small number of pharmaceutical drugs that are conjugated to glycine, the pathway has not yet been characterised in detail. Therefore, one of the objectives of this thesis was to develop a better understanding of glycine conjugation and its role in metabolism. In humans and animals a number of endogenous and xenobiotic organic acids are conjugated to glycine. Glycine conjugation has generally been assumed to be a detoxification mechanism, increasing the water solubility of organic acids in order to facilitate urinary excretion. However, recently it was proposed that the role of the amino acid conjugations, including glycine conjugation, is to regulate systemic levels of amino acids that are also utilised as neurotransmitters in the central nervous systems of animals. The glycine deportation hypothesis was based on the observation that, compared to glucuronidation, glycine conjugation does not significantly increase the water solubility of aromatic acids. A thorough review of the literature for this thesis showed that the major role of glycine conjugation, however, is to dispose of the end products of phenylpropionate metabolism. The review also introduced the new perspective that mitochondrial glycine conjugation prevents the accumulation of benzoate in the mitochondrial matrix by forming hippuric acid a less lipophilic conjugate that can be more readily transported out of the mitochondria. Although organic anion transporters can export benzoate from the matrix, this process would likely be futile because benzoic acid can simply diffuse back into the matrix. Hippurate, however, is significantly less lipophilic and therefore less capable of diffusing into the matrix. It is therefore not the transport out of the mitochondrial matrix that is facilitated by glycine conjugation, but rather the ability of the glycine conjugates to re-enter the matrix that is decreased. Lastly, glycine conjugation of benzoate also exacerbates the dietary deficiency of glycine in humans. Because the resulting shortage of glycine can negatively influence brain neurochemistry and the synthesis of collagen, nucleic acids, porphyrins, and other important metabolites, the risks of using benzoate as a preservative should not be underestimated.
To date, no defect of the glycine conjugation pathway has been reported and this, together with the fact that GLYAT plays an important role in hepatic metabolism, suggests that this pathway is essential for survival. GLYAT activity affects mitochondrial ATP production, glycine availability, CoASH availability and the toxicity of various organic acids. Therefore, variation in the glycine conjugation pathway could influence liver cancer, musculoskeletal development and mitochondrial energy metabolism. Significant interindividual variation exists in glycine conjugation capacity. The molecular basis for this variability is not known. The main aim of this thesis was to investigate and characterise the genetic variation in the coding region of the GLYAT gene. This was accomplished by firstly, investigating the influence of non-synonymous single nucleotide polymorphisms (SNPs) on the enzyme activity of a recombinant human GLYAT and secondly, by analysing the level of genetic
variation in the coding region of the GLYAT gene using existing worldwide population data. To investigate the influence of non-synonymous SNPs in the GLYAT gene on the enzyme activity, a recombinant human GLYAT was prepared, and characterised. Site-directed mutagenesis was used to generate six variants of the enzyme (K16N; S17T; R131H; N156S; F168L; R199C). The variants were expressed, purified, and enzymatically characterised. The enzyme activities of the K16N, S17T and R131H variants were similar to that of the wild-type, whereas the N156S variant was more active, the F168L variant less active, and the R199C variant was inactive. The results showed that SNP variations in the human GLYAT gene can influence the kinetic properties of the enzyme. The genetic variation data of the human GLYAT open reading frame (ORF) available on public databases was investigated by formulating the hypothesis that due to the essential nature of the glycine conjugation pathway, the genetic variation in the ORF of the GLYAT gene should be low and that deleterious alleles will be found at low frequencies. Data from the i) 1000 Genome Project, ii) the HapMap Project, and iii) the Khoi-San/Bantu Sequencing Project was downloaded from available databases. Sequence data of the coding region of a small cohort of South African Afrikaner Caucasian individuals was also generated and included in the analyses. In the GLYAT ORF of the 1537 individuals analysed, only two haplotypes (S156 and T17S156) out of 14 haplotypes were identified in all populations as having the highest haplotype frequencies (70% and 20% respectively). The S156C199 and S156H131 haplotypes, which have a deleterious effect on the enzyme activity of a recombinant human GLYAT, were detected at very low frequencies. The results of this study indicated that the GLYAT ORF is remarkably conserved, which supports the hypothesis that the glycine conjugation pathway is an essential detoxification pathway. The findings presented in this thesis highlight the importance that future investigations should determine the in vivo capacity of the glycine conjugation pathway for the detoxification of benzoate and other xenobiotics.PhD (Biochemistry), North-West University, Potchefstroom Campus, 2015