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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Metabolism of phytoalexins and analogs, and inhibitors of brassinin detoxification in Leptosphaeria maculans

2012 April 1900 (has links)
Detoxification of canola chemical defenses (phytoalexins and others) is an important mechanism used by the blackleg fungus Leptosphaeria maculans/Phoma lingam to overcome the plant’s natural defenses. Phytoalexins are anti-microbial defense metabolites produced de novo by plants in response to pathogen attack and other forms of stress. L. maculans is successful in detoxifying several cruciferous phytoalexins into different products. For example, brassinin, a key phytoalexin from crucifers, is transformed into indole-3-carboxaldehyde. This thesis includes investigation of phytoalexin metabolism by L. maculans and related work: (i) transformation pathways of cruciferous phytoalexins and analogues; (ii) design and synthesis of potential inhibitors of brassinin detoxification. In continuation of previous work, homologues, analogues and structural relatives of brassinin were analysed for metabolism by L. maculans. Products of metabolism of these compounds were identified and the overall metabolic pathways were established. It was concluded that structural relatives of brassinin metabolized differently from brassinin. Antifungal bioassays of the products suggested that all these transformations were detoxification reactions. Among the phytoalexins, rapalexin A was not metabolized whereas, erucalexin was metabolized. Results of these metabolism studies using L. maculans along with the syntheses and antifungal activities of the metabolites will be presented. In the second part of thesis, inhibition of the detoxification of brassinin by L. maculans using quinolines and isoquinolines was investigated. These compounds resulted from replacement of indolyl containing structures with quinoline and isoquinoline moieties, and various substitutions such as phenyl, thiazolyl, bromo, chloro, hydroxy and methoxy groups. All these compounds were tested for their effect on brassinin detoxification and antifungal activity. Overall, a significant effect on the rate of brassinin detoxification in cultures of L. maculans was detected in the presence of compounds 6-bromo-2-phenylquinoline, 2-phenylquinoline, 3-phenylquinoline, 1-thiazolylisoquinoline. 6-Bromo-2-phenylquinoline was the most effective compound in slowing down the metabolism of brassinin and also was a weak inhibitor of the growth of L. maculans (virulent on canola). Results of the syntheses and evaluation of the compounds are discussed.
12

Biotransformation of the Phytoalexins Brassinin, Brassilexin and Camalexin by <i>Alternaria brassicicola</i>

Islam, Mohammad Showkatul 12 January 2009 (has links)
Chemical investigation of the transformation of the crucifer phytoalexins brassinin, brassilexin and camalexin by the phytopathogenic fungus <i>Alternaria brassicicola</i> was carried out. The objectives of this study included:<p> 1) the isolation and characterization of the metabolites of biotransformation of brassinin, brassilexin and camalexin by <i>A. brassicicola</i>;<p> 2) determination of the antifungal activity of these phytoalexins and their metabolites against <i>A. brassicicola.</i><p> The phytoalexins were synthesized and characterized using HPLC retention time tR, 1H NMR, 13C NMR, LC-MS and HRMS-ESI data. The metabolites of the biotransformation were also synthesized and characterized similarly. The metabolism of each phytoalexin and their metabolites was studied by analyzing broth extracts by HPLC. The percent inhibition of growth of <i>A. brassicicola</i> was determined by radial growth mycelial assays.<p> The biotransformation of brassinin by <i>A. brassicicola</i> afforded Nb-acetyl-3-indolylmethylamine via indole-3-methylamine intermediate. Brassilexin was metabolized to 3-(amino)methyleneindoline-2-thione by the reduction of the isothiazole ring. Camalexin did not appear to be metabolized or the metabolism was very slow. The results of biotransformation and bioassay studies established that the metabolism of brassinin by <i>A. brassicicola</i> was a detoxification process. However, these studies using brassilexin did not provide a rigorous conclusion. Camalexin showed strong inhibition of growth against <i>A. brassicicola</i> suggesting its importance in defense against this pathogen.
13

Molecular methods for genotyping selected detoxification and DNA repair enzymes / J. Labuschagne

Labuschagne, Jeanine January 2010 (has links)
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.
14

Molecular methods for genotyping selected detoxification and DNA repair enzymes / J. Labuschagne

Labuschagne, Jeanine January 2010 (has links)
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.
15

Alcohol withdrawal syndrome : characterisation, predictors of severity, and relationship to relapse / Rachel Emilie Humeniuk.

Humeniuk, Rachel January 1999 (has links)
Bibliography: leaves 246-263. / xiii, 263 leaves : col. ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Previous investigations have established that there is a syndrome that occurs with abstinence from alcohol, and that it is characterised by certain signs and symptoms. This thesis aims to redress the paucity of information on symptom intensity and duration, predictors of withdrawal severity, and relationship of withdrawal severity to relapse. / Thesis (Ph.D.)--University of Adelaide, Dept. of Clinical and Experimental Pharmacology, 2000
16

Aspectos da resposta imune frente a antigenos proteicos irradiados com sup(60)Co

ALVES, JANAINA B. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:49:16Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:33Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
17

Aspectos da resposta imune frente a antigenos proteicos irradiados com sup(60)Co

ALVES, JANAINA B. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:49:16Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:33Z (GMT). No. of bitstreams: 0 / Considerando os efeitos da radiação gama sobre proteínas e a capacidade do sistema imune de reconhecer macromoléculas modificadas, decidimos avaliar alguns aspectos imunológicos de camundongos B10.PL frente a ovalbumina e bothropstoxina–1 (BTHX-1), nas formas nativa e irradiada. Para avaliar prováveis modificações estruturais nas moléculas das proteínas após o processo de irradiação (radiação gama de 60Co), foi realizada a eletroforese em gel de poliacrilamida 15% para a ovalbumina e para a BTHX-1, nas formas nativa e irradiada. A ovalbumina também foi submetida à cromatografia de exclusão molecular, enquanto a BTHX-1 foi submetida à espectrometria de massa. Os resultados destes ensaios mostraram que a radiação gama foi capaz de promover alterações nas moléculas de ovalbumina e BTHX-1. A fim de avaliar a toxicidade da BTHX-1 irradiada em relação à nativa realizou-se um ensaio de citotoxicidade celular em células CHO. O resultado mostrou que a toxina na sua forma irradiada apresentou, aproximadamente, cinco vezes menos toxicidade do que a toxina na sua forma nativa. Com relação aos aspectos imunológicos, foram realizados ensaios de produção e identificação de anticorpos, nos quais, os animais foram imunizados com ovalbumina e BTHX-1, nas formas nativa ou irradiada. Observou-se que as proteínas nativas induziram, preferencialmente, uma resposta do tipo Th2, enquanto que as proteínas irradiadas induziram uma resposta do tipo Th1. Realizou-se um ensaio de proliferação celular para avaliar o comportamento de esplenócitos, retirados do baço de camundongos B10.PL, imunizados com ovalbumina e BTHX-1, nativas ou irradiadas, cultivados em presença de ambas as formas das proteínas. Em relação à ovalbumina, os resultados mostraram que tanto as células dos animais imunizados com a ovalbumina nativa como aquelas dos animais imunizados com a proteína na sua forma irradiada apresentaram crescimento semelhante. No caso da BTHX-1, os resultados mostraram que as células dos animais imunizados com a toxina irradiada foram capazes de reconhecer a forma nativa da toxina, pois apresentaram crescimento semelhante ao das células dos animais imunizados com a BTHX-1 nativa. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
18

Characteristics of Patients and their Treatments at an Inpatient Facility for Detoxification and Treatment of Chemical Dependence

Gomez, Rosalinda, Holt, Jennifer, Huynh, Claire January 2005 (has links)
Class of 2005 Abstract / Objectives: The purpose of this study was to determine the demographics of co-morbid disorders and drug abuse characteristics of patients admitted to an inpatient facility for detoxification and treatment of chemical dependency to characterize the treatment programs including the psychiatric medication usage and prescribing patterns and to identify differences between men and women. Methods: Criteria inclusion for admittance included a diagnosis of chemical dependence at Sierra Tucson Behavioral Health Hospital during the time of January through June 2004. Patients were admitted to that were diagnosed with a chemical dependency, identified using a past hospital census. Charts of previously discharged patients were obtained from the medical records department of the institution. Specific variables from each chart were extracted for further analysis utilizing a data form. Results: 285 (170 women and 115) men chemically dependent patients that were admitted during the six-month study period. In this patient population there was a high incidence, 76.84%, of co-morbid psychiatric conditions. The most frequently abused drugs in men were alcohol, nicotine, and cocaine. The most frequently abused drugs in women were alcohol, nicotine, and opiates. Men and women were most frequently placed on a librium based alcohol detoxification program, and secondly a buprenorphine based opiate detoxification program. There was statistical significant improvement in the of Beck Depression Inventory scale (BDI), Beck Hopelessness scale (BHS), and Global Assessment Function (GAF) scores at admit and discharge and a downward trend in Clinical Institute Withdrawal Assessment (CIWA) and Clinical Opiate Withdrawal (COW) scores. Implications: There was a high incidence of co-morbid psychiatric conditions such as depression and anxiety that were present in both genders. In men, Attention Deficit and Hyperactivity Disorder/ Attention Deficit Disorder (ADHD/ADD) was an additional common condition observed, while in women eating disorders were observed. The treatments provided led to an overall improvement in GAF, BDI, BHS, CIWA and COW scores indicating effectiveness of the treatment program.
19

Effects of a Same-Day Post-detoxification Residential Alcohol Use Disorder Treatment Admission Policy

Garland, Benjamin H., Mindrup, Robert M., Zottarelli, Lisa K., McCarley, Jill D. 01 January 2021 (has links)
This study examined pre- and post-implementation of a same-day post-detoxification residential admission policy within a Veteran Health Administration (VHA) facility to determine improved outcomes consistent with the larger literature. A single facility sample of participants who received detoxification from alcohol pre- and post-policy change was identified utilizing administrative and health record data. Chi-square testing and independent samples T-testing evaluated changes between a 2018 pre-policy cohort and a 2019 post-policy cohort. Policy implementation of same-day admissions to residential treatment after detoxification resulted in statistically significant change in instances of waiting, wait times for participants who waited, no-show, and readmissions during the six months following inpatient discharge. Mortality, cancellation rates, and discharge type did not differ significantly. These findings further support previous research that outlines the relationship between efficient post-detoxification continuity of care and increased positive outcomes.
20

Toxicological Analysis of the Neonicotinoid Insecticide Imidacloprid to  Honey Bees, Apis mellifera, of Different Colonies

Langberg, Kurt 14 October 2016 (has links)
The honey bee, Apis mellifera, provides about $15 billion USD in crop value each year in the U.S. alone in the form of pollination services. Since 2006, commercial beekeepers have reported an average annual overwintering loss of about 28.6% of all managed colonies. There are many factors that are thought to contribute to colony loss including bee-specific pests (e.g. the Varroa destructor mite), bee-specific pathogens (e.g. Nosema fungus), modern beekeeping practices, diminished genetic variability, poor queens, climate change, and exposure to agricultural pesticides. While not the single cause of colony loss, the neonicotinoid insecticides elicit sublethal effects to honey bees that could increase their sensitivities to other stressors that affect colony health. Previous studies found that honey bees have differential sensitivities to the neonicotinoid insecticide imidacloprid, which suggest a mechanism of tolerance to the insecticide in certain colonies. In this study, I examined the imidacloprid sensitivity of honey bees collected from different colonies. After determining a range of LC50 values in the tested colonies, I examined the metabolic detoxification activities of honey bees collected from two colonies that represented the highest and lowest LC50 values, between which there was a 36-fold difference in their LC50 values. I discovered that of the three main families of metabolic detoxification enzymes, general esterases, cytochrome P450 monooxygenases, and glutathione S-transferases (GSTs), a reduction of GST activity with diethyl maleate (DEM) significantly increased imidacloprid-mediated mortality to the honey bees. A comparative analysis of GST kinetic activity from imidacloprid-susceptible and -insensitive honey bees revealed a lower bimolecular inhibition rate constant (ki) for imidacloprid-insensitive individuals (5.07 ± 0.098 nmol/min/mg protein) compared to the imidacloprid-sensitive honey bees (17.23 ± 1.235 nmol/min/mg protein). The IC50 of DEM estimated for bees from each colony showed that the imidacloprid-susceptible honey bees possess a higher IC50 (10 μM) than that of the tolerant honey bees (3 μM). These data suggest that the GSTs in the imidacloprid-tolerant honey bees might be a more efficient detoxification mechanism for the conjugation and elimination of imidacloprid, or imidacloprid metabolites, compared to that of imidacloprid-susceptible honey bees. Therefore, I hypothesize that the differences in metabolic detoxification enzyme activities of honey bees collected from different colonies can result in the differential toxicities of honey bees exposed to neonicotinoid insecticides, such as imidacloprid. However, a thorough examination of imidacloprid detoxification in honey bees is warranted to confirm this hypothesis. / Master of Science in Life Sciences

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