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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.
41

The effects of vancomycin resistance selection and magnesium on resistance expression in methicillin-resistant Staphylococcus aureus

Pfeltz, Richard F. Wilkinson, Brian J. January 1999 (has links)
Thesis (Ph. D.)--Illinois State University, 1999. / Title from title page screen, viewed July 20, 2006. Dissertation Committee: Brian J. Wilkinson (chair), Radheshyam K. Jayaswal, Alan J. Katz, Anthony J. Otsuka, David L. Williams. Includes bibliographical references and abstract. Also available in print.
42

Distribution and mobility of antibiotic resistant genes in oral/urogentital [sic] bacteria

Leng, Zhongtai. January 1998 (has links)
Thesis (Ph. D.)--University of Washington, 1998. / Includes bibliographical references.
43

The hypertension-prone man a study on the pathogenesis of hypertension with regard to insulin sensitivity /

Endre, Tomas. January 1997 (has links)
Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted.
44

Hydrodynamics of advanced high-speed sealift vessels.

Lazauskas, Leo V. January 2005 (has links)
There is at present great interest in large ships capable of carrying substantial cargo at speeds in excess of 40 knots. At the same time, there are large gaps in our understanding of the hydrodynamics, structural engineering, and economics of high-speed vessels. Monohulls, catamarans, trimarans, surface effect ships, and air cushion vehicles are considered in the present work. The total resistance of these vehicles is divided into separate components which are estimated using different methods. Skin-friction is estimated using Grigson's algorithm which gives much better predictions of flat plate skin-friction than the traditional ITTC method. Wave resistance of displacement hulls is estimated using Michell's thin-ship theory: a similar theory is used for the wave resistance of travelling pressure distributions. Several simple formulae are derived that can be used in the preliminary design stage of catamarans to estimate optimum demihull separation. Memetic algorithm techniques are used to find vessels with minimum (calm-water) total resistance. Optimal geometric parameters are found for vessels of 1200 tonnes under a variety of geometric limitations and constraints on upright stability, at design speeds of 50 knots and 75 knots. Estimates are made of the principal weight components of the optimal vessels. Empirical formulae for the efficiencies of powerplants and propulsors then enable estimates to be made of the maximum range, the cargo capacity, and the fuel consumption. / Thesis (M.Sc.)--School of Mathematical Sciences, 2005.
45

Nondormant Alfalfa Varieties for Arizona 2015

Ottman, Michael J. 09 1900 (has links)
Revision of AZ1267 / 2 pp. / Alfalfa varieties differ in fall dormancy, defined as growth during the fall. Nondormant alfalfa varieties are usually planted in mild winter areas for their ability to grow in the late fall, winter, and early spring. Select alfalfa varieties that have resistance to potential pest problems. Alfalfa varieties are available that have salt tolerance or are Roundup Ready. Ratings are provided in this publication. Many of the varieties listed in this publication have been tested for yield and final stand by the University of Arizona in small plot trials.
46

Resistance to pyrethroid and organophosphate insecticides in the pink bollworm, Pectinophora gossypiella (Saunders).

Osman, Abdelgadir Ahmed. January 1989 (has links)
Baseline data on susceptibility levels to azinphosmethyl and permethrin were generated on five field-collected populations of the pink bollworm, Pectinophora gossypiella (Saunders), from Arizona and Southern California, relative to a standard susceptible laboratory strain. The field strains showed less than 2-fold resistance to azinphosmethyl but exhibited variable levels (1.3- to 18.3-fold) of resistance to permethrin. Resistance of pink bollworms to permethrin seems to be correlated with the pattern of insecticide-use prevalent in the localities studied. Strains from Yuma, Phoenix and Westmoreland exhibited highest levels of resistance to permethrin. Synergism of permethrin with an oxidase inhibitor, piperonyl butoxide (PBO), and an esterase inhibitor, S,S,S-tributyl phosphorotrithioate (DEF), produced less than 2-fold synergism in the Yuma strain. Results suggest that nonmetabolic factor(s) may be involved in permethrin resistance of the Yuma field strain since neither PBO nor PBO/DEF combination suppressed resistance completely. It is possible that pink bollworm resistance is at least partially conferred by the khr-gene. Rearing of two field strains collected from Marana and Yuma under insecticide-free conditions resulted in reversion of resistance in four and five generations, respectively, to levels close to that found in the susceptible laboratory strain. Permethrin-resistance in these field strains is unstable and is apparently in its early phase of development. Monitoring of resistance in field strains should be performed preferably in the F₁ generation. Subsequently, selection studies were performed on both larval and adult stages to investigate the capacity of the pink bollworm to develop resistance in both life-stages. Selection of larvae with both azinphosmethyl and permethrin resulted in higher levels of resistance in larvae than in adults. Results suggest that azinphosmethyl possesses a low degree of selectivity for development of resistance in pink bollworm adults. Fourteen to 16 generations of selection with azinphosmethyl and permethrin produced ca. 2- and 9-fold resistance, respectively, in the adult stage. A laboratory-selected strain showing ca. 13-fold resistance was used in reciprocal crosses with a susceptible laboratory strain. The F₁ results suggested that inheritance of permethrin resistance was autosomal and partially dominant. Chi-square analysis of responses of backcross progeny indicated that resistance seems to be conferred by a major gene under the influence of minor gene(s).
47

Antimicrobial resistance gene monitoring in aquatic environments

Rowe, Will January 2016 (has links)
This dissertation documents the development of an environmental framework for monitoring antimicrobial resistance gene (ARG) dissemination in the aquatic environment. The work opens with a review of the relevant literature and outlines the importance of an environmental framework for monitoring ARG dissemination as part of antimicrobial resistance risk assessments. The ability to interrogate sequencing data quickly and easily for the presence of ARGs is crucial in order to facilitate their monitoring in the environment. As current laboratory methods for the detection and surveillance of antimicrobial resistant bacteria in the environment were limited in their effectiveness and scope, the dissertation begins by describing the design and implementation of a Search Engine for Antimicrobial Resistance (SEAR), a pipeline and web interface for detection of horizontally-acquired ARGs in raw sequencing data. The suitability of metagenomic methods for monitoring the ARG content of effluents from faecal sources was then assessed via a pilot study of a river catchment. Novel metagenomes generated from effluents entering the catchment were interrogated for ARGs. The relative abundance of ARGs in effluents were determined to be higher relative to the background environment, as were sequences relating to human and animal pathogens and mobile genetic elements. Thus, effluents were implicated in the dissemination of ARGs throughout the aquatic environment. To determine if ARGs were potentially in use in the environment, the expression of ARGs within effluents was then evaluated across a series of longitudinal samples through the use of metatranscriptomics, and the presence of potential environmental antimicrobial selection pressures was examined. This demonstrated that the abundance of ARGs, as well as antimicrobial usage at the effluent source, was correlated with the transcription of ARGs in aquatic environments. The work described in this dissertation has also found that horizontally transmitted ARGs were present in pathogenic endospore-forming bacteria commonly found across the aquatic environment, potentially providing a mechanism for ARG persistence in the environment. Finally, these findings were integrated into a universal framework for monitoring ARG dissemination in aquatic environments and used to highlight the developments required to incorporate this framework into future environmental ARG research and to facilitate antimicrobial resistance risk assessments.
48

A study of multi-drug efflux pumps in acinetobacter.

January 2003 (has links)
Chau Sze-lok. / Thesis submitted in: December 2002. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 221-245). / Abstracts in English and Chinese. / ABSTRACT (English) --- p.i / ABSTRACT (Chinese) --- p.iii / ACKNOWLEDGMENT --- p.v / LIST OF CONTENTS --- p.vii / LIST OF TABLES --- p.xiv / LIST OF FIGURES --- p.xvii / ABBREVIATIONS --- p.xx / TERMS --- p.xxi / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / (PART A) / Chapter 1.1 --- Acinetobacter spp --- p.1 / Chapter 1.2 --- Clinical importance of Acinetobacter --- p.4 / Chapter 1.3 --- Resistance mechanisms / Chapter 1.3.1 --- Intrinsic resistance --- p.7 / Chapter 1.3.2 --- Acquired resistance --- p.15 / Chapter 1.4 --- Resistance in Acinetobacter --- p.21 / Chapter 1.4.1 --- The efflux system in Acinetobacter --- p.22 / Chapter 1.4.2 --- Other antibiotic resistance mechanisms in Acinetobacter --- p.23 / (PART B) / Chapter 1.5 --- Methods used in this study --- p.29 / Chapter 1.6 --- Rationale of this study --- p.35 / Chapter 1.7 --- Objectives --- p.37 / Chapter CHAPTER 2 --- MATERIALS AND METHODS --- p.39 / Chapter 2.1 --- Bacterial strains and isolates / Chapter 2.1.1 --- Isolates for studying blaIMP-4 --- p.39 / Chapter 2.1.2 --- Isolates for studying adeB --- p.39 / Chapter 2.1.3 --- Isolates for investigation of other efflux pump(s)in Acinetobacter GDG3 --- p.40 / Chapter 2.1.4 --- Isolates for studying the distribution of efflux pumps --- p.40 / Chapter 2.1.5 --- Reference strains --- p.41 / Chapter 2.2 --- Materials / Chapter 2.2.1 --- Sources of materials --- p.42 / Chapter 2.2.2 --- Buffers and solutions --- p.45 / Chapter 2.3 --- Instruments and software --- p.46 / Chapter 2.4 --- General bacteriological techniques / Chapter 2.4.1 --- Bacteriological dientification --- p.47 / Chapter 2.4.2 --- Stock isolates --- p.48 / Chapter 2.4.3 --- Retrieval of isolates --- p.48 / Chapter 2.5 --- General molecular biology techniques / Chapter 2.5.1 --- Agarose gel electrophoresis --- p.49 / Chapter 2.5.2 --- Polymerase chain reaction (PCR) --- p.50 / Chapter 2.5.3 --- Amplified Ribosomal Restriction DNA Analysis (ARDRA) --- p.51 / Chapter 2.5.4 --- Pulsed field gel electrophoresis (PFGE) --- p.53 / Chapter 2.5.5 --- Minimal inhibitory concentration (MIC) --- p.55 / Chapter 2.5.6 --- Antibiotic sensitivity test - disc diffusion test --- p.56 / Chapter 2.5.7 --- Detection of the presence of the common resistance mechanisms --- p.57 / Chapter 2.5.8 --- TA Cloning --- p.60 / Chapter 2.5.9 --- DNA Sequencing --- p.62 / Chapter 2.5.10 --- Sequence analysis --- p.64 / Chapter 2.5.11 --- CYBR Green Assay --- p.65 / Chapter 2.5.12 --- Complementary DNA (cDNA) preparation --- p.66 / Chapter 2.5.13 --- Real time RT-PCR --- p.67 / Chapter 2.5.14 --- Construction of Genome Walker Libraries --- p.69 / Chapter 2.6 --- "Selection of acinetobacters from ICU, blood culture and other clinical isolates" / Chapter 2.6.1 --- Isolates from existing stock cultures --- p.71 / Chapter 2.6.2 --- New isolates obtained for this study --- p.71 / Chapter 2.7 --- Study of expression level of the blaIMP-4 gene / Chapter 2.7.1a --- Verification of the specificity of primers for blaIMP-4 --- p.72 / Chapter 2.7.1b --- Verfication of the specificity of primers for 16S rRNA gene --- p.73 / Chapter 2.7.1c --- Construction of standard curve --- p.76 / Chapter 2.7.2 --- Expression levels of blaIMP-4 and meropenem MICin blaIMP-4+ blood culture isolates --- p.77 / Chapter 2.7.3 --- Intra-assay reproducibility --- p.11 / Chapter 2.7.4 --- Detection of the production of metallo-β-lactamase --- p.77 / Chapter 2.8 --- Study of adeABC expression / Chapter 2.8.1 --- Determination of the presence of the adeB gene --- p.78 / Chapter 2.8.2 --- Entirety of the adeABC operon --- p.79 / Chapter 2.8.3 --- Expression level of the adeB gene --- p.82 / Chapter 2.8.4 --- Expression levels of adeB in sets of serial isolates --- p.84 / Chapter 2.8.5 --- Intra-assay reproducibility --- p.84 / Chapter 2.8.6 --- Inter-assay reproducibility --- p.84 / Chapter 2.9 --- Investigation of other efflux pumps in acinetobacter genomic DNA group3 / Chapter 2.9.1 --- Detection of adeB homologue in a genomic DNA group 3isolate --- p.85 / Chapter 2.9.2 --- Chromosome walking of the adeB-like genes --- p.87 / Chapter 2.9.3 --- Sequences of AdeE and AdeY and their comparison --- p.105 / Chapter 2.9.4 --- Topology prediction of AdeE and AdeY --- p.105 / Chapter 2.9.5 --- The role of the putative pump AdeE --- p.106 / Chapter 2.10 --- Distribution of AdeB and the putative efflux pumps AdeE and AdeY in acinetobacters from different bacterial collections / Chapter 2.10.1 --- Distribution of adeB and the putative pumps (adeE and adeY) in blood cultures (1997-2000) --- p.113 / Chapter 2.10.2 --- Confirmation of the identity of the amplification products of adeE and ade Y in blood culture isolate (1997-2000) --- p.115 / Chapter 2.10.3 --- The presence of adeE in GDG 3 acinetobacters from different sources --- p.116 / Chapter 2.10.4 --- "The presence of adeB, adeE and adeY in antibiotic susceptibility" --- p.116 / Chapter 2.10.5 --- "adeB, adeE and adeY and the clonally and epidemiologically related sets of isolates" --- p.116 / Chapter 2.10.6 --- "adeB, adeE and adeY and the blaIMP-4+ isolates" --- p.116 / Chapter CHAPTER 3 --- "SELECTION OF ACINETOBACTERS FROM ICU, BLOOD CULTURE AND OTHER CLINICAL ISOLATES" --- p.119 / Chapter 3.1 --- Results / Chapter 3.1.1 --- Isolates from existing stock cultures --- p.119 / Chapter 3.1.2 --- New isolates obtained for this study --- p.127 / Chapter 3.2 --- Discussion / Chapter 3.2.1 --- Identification of clonally related isolates by PFGE --- p.129 / Chapter 3.2.2 --- Correlation between the presence of common resistance mechanisms and the changes in antimicrobial susceptibility --- p.129 / Chapter 3.2.3 --- Development of resistance in serial isolates --- p.131 / Chapter CHAPTER 4 --- STUDY OF blaIMP-4 EXPRESSION --- p.133 / Chapter 4.1 --- Results / Chapter 4.1.1 --- Study of expression level of the blaIMP-4 gene --- p.134 / Chapter 4.1.2 --- Expression levels of blaIMP-4 and meropenem MIC in blaIMP-4+ blood culture isolates --- p.136 / Chapter 4.1.3 --- Intra-assay reproducibility \ --- p.37 / Chapter 4.1.4 --- Detection of the production of metallo-β-lactamase --- p.140 / Chapter 4.2 --- Discussion / Chapter 4.2.1 --- Dissociation curve --- p.140 / Chapter 4.2.2 --- Reproducibility of real time RT-PCR --- p.140 / Chapter 4.2.3 --- Relationship between mRNA level of blaIMP-4 and the meropenem MIC --- p.142 / Chapter CHAPTER 5 --- STUDY OF adeABC EXPRESSION --- p.145 / Chapter 5.1 --- Results / Chapter 5.1.1 --- Determination of the presence of the adeB gene --- p.145 / Chapter 5.1.2 --- Entirety of the adeABC operon --- p.146 / Chapter 5.1.3 --- Expression level of the adeB gene --- p.148 / Chapter 5.1.4 --- Expression levels of adeB in sets of serial isolates --- p.151 / Chapter 5.1.5 --- Intra-assay reproducibility --- p.154 / Chapter 5.1.6 --- Inter-assay reproducibility --- p.154 / Chapter 5.2 --- Discussion / Chapter 5.2.1 --- Detection of adeB --- p.156 / Chapter 5.2.2 --- Entirety of the adeABC operon --- p.156 / Chapter 5.2.3 --- Reproducibility of real time RT-PCR --- p.157 / Chapter 5.2.4 --- Relationship between adeB-mRNA level and antimicrobial susceptibility --- p.157 / Chapter CHAPTER 6 --- INVESTIGATION OF OTHER EFFLUX PUMPS IN ACINETOBACTER GENOMIC DNA GROUP3 --- p.159 / Chapter 6.1 --- Results / Chapter 6.1.1 --- Detection of adeB homologue in a genomic DNA group3 isolate --- p.159 / Chapter 6.1.2 --- Chromosome walking of the adeB-like genes --- p.162 / Chapter 6.1.3 --- Sequences of AdeE and AdeY and their comparison --- p.173 / Chapter 6.1.4 --- Topology prediction of AdeE and AdeY --- p.175 / Chapter 6.1.5 --- The role of the putative pump AdeE --- p.177 / Chapter 6.2 --- Discussion / Chapter 6.2.1 --- The AdeE RND transporter --- p.181 / Chapter 6.2.2 --- The theoretical AdeY protein --- p.183 / Chapter CHAPTER 7 --- DISTRIBUTION OF AdeB AND THE PUTATIVE EFFLUX PUMPS AdeE and AdeY IN ACINETOBACTERS FROM DIFFERENT BACTERIAL COLLECTIONS --- p.184 / Chapter 7.1 --- Results / Chapter 7.1.1 --- Distribution of adeB and the putative pumps (adeE and ade Y) in blood cultures (1997-2000) --- p.184 / Chapter 7.1.2 --- Confirmation of the identity of the amplification products of adeE and adeY in blood culture isolates (1997-2000) --- p.187 / Chapter 7.1.3 --- The presence of adeE in GDG 3 acinetobacters from different sources --- p.195 / Chapter 7.1.4 --- "The presence of adeB, adeE and ade Y in antibiotic susceptibility" --- p.196 / Chapter 7.1.5 --- "adeB, adeE and adeY and the clonally and epidemiologically related sets of isolates" --- p.202 / Chapter 7.1.6 --- "adeB, adeE and adeY and the blaIMP-4+ isolates" --- p.202 / Chapter 7.2 --- Discussion / Chapter 7.2.1 --- PCR-RFLP typing --- p.205 / Chapter 7.2.2 --- Distribution of adeB --- p.205 / Chapter 7.2.3 --- Distribution of adeE --- p.206 / Chapter 7.2.4 --- Distribution of adeY --- p.207 / Chapter 7.2.5 --- Distribution of adeE and adeY in GDG 3 isolates --- p.207 / Chapter CHAPTER 8 --- GENERAL DISCUSSION --- p.209 / Chapter 8.1 --- Significance of adeB and the putative pumps (adeE and adeY) --- p.211 / Chapter CHAPTER 9 --- CONCLUSION --- p.218 / Chapter 9.1 --- Conclusion --- p.218 / Chapter 9.2 --- Future Plan --- p.219 / REFERENCES --- p.221 / APPENDIX --- p.246 / Appendix1 --- p.246 / Appendix2 --- p.247 / Appendix3 --- p.252 / Appendix4 --- p.253 / Appendix5 --- p.259
49

Is there an association between trimethoprim-sulfamethoxazole use as prophylaxis and multi-drug resistant non-typhoidal salmonella? A secondary data analysis of antibiotic co-resistance surveillance data in South Africa - 2003-2005

Nanoo, Ananta 10 March 2011 (has links)
MSc (Med), Epidemiology and Biostatistics, Faculty of Health Sciences, University of the Witwatersrand / Introduction Given the increasing prevalence of non-typhoidal salmonella in humans, especially as an opportunistic illness associated with HIV, enhanced surveillance for non-typhoidal salmonella (NTS), including screening for antibiotic resistance, is conducted annually in South Africa. We aimed to determine whether there is an association between trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis and multi-drug resistant NTS infection, to establish whether various factors modify the relationship between TMP-SMX resistance and invasive NTS infection, to examine whether these associations vary by province, and to quantify the resistance rates of NTS to a range of antibiotics. Methods This study was a secondary analysis of enhanced surveillance data on NTS collected between 2003 and 2005. We used descriptive methods to assess the prevalence of NTS by year, province and serotype, and to determine the prevalence of four MDR patterns. Univariate and multivariate regression models were used to investigate the relationships between TMP-SMX prophylaxis and MDR NTS. Univariate logistic regression was used to assess the relationship between invasive NTS and TMP-SMX resistance. Results TMP-SMX prophylaxis is associated with the ACKSSuT pattern (OR 1.91, 95% CI 1.14 – 3.19, p=0.0080) and the AKSSuT MDR pattern (OR 2.00, 95% CI 1.26 – 3.15, p=0.0015). Being on TMP-SMX prophylaxis is associated with an increased odds of having at least one of the four MDR patterns investigated (OR 1.43, 95% CI 1.00 – 2.04, p=0.0388). We also found high rates of resistance to all antibiotics tested except for ciprofloxacin and imipenem. The highest resistance rate was observed for sulfamethoxazole (>75.85%). S. enterica Isangi isolates showed the highest levels of resistance, with 94.43% having at least one MDR pattern. Other factors significantly associated with MDR NTS were ESBL production, prior treatment with antibiotics, HIV status and resistance to TMP-SMX. Discussion and conclusions Isolates from patients on TMP-SMX prophylaxis were associated with an increased odds of having the ACKSSuT and AKSSuT MDR patterns, not taking into account other explanatory factors. These associations did not remain significant when possible confounders were taken into account. Despite the threat of increased multi-drug resistance, TMP-SMX prophylaxis remains important in certain clinical settings.
50

The effects of concurrent training on performance variables in previously untrained males

Glowacki, Shawn Philip 17 February 2005 (has links)
Research has shown conflicting results involving interference of strength development with combined resistance and endurance training. Purpose: To examine if endurance training and resistance training performed concurrently would produce different performance and physiological results when compared to each type of training alone. Methods: Forty-five untrained males were recruited and randomly assigned to one of three 12 wk training groups. An endurance training (ET, N=12) group trained by running (2-3 days/week, 20-40 min, 65- 80% HRR), a resistance training (RT, N=13) group performed a resistance training program (2-3 days/week, 3 sets/8 exercises, 6-10 reps, 75-85% 1RM), and a concurrent training (CT, N=16) group performed both the endurance and resistance training programs (5 days/week, even # week 3 endurance/2 resistance workouts, odd # week 3 resistance/2 endurance workouts). All groups were tested for all the following variables prior to and following training: percent body fat, VO2max, isokinetic-maximal torque and avg. power at two speeds, 1RM leg press, 1 RM bench press, vertical jump, lower body power (as calculated by the Lewis formula) and 40-yard dash time. Results: Percent body fat was significantly (p≤.05) decreased in both the ET and CT groups. Only the ET group significantly improved VO2max (+8.24%). Minimal changes were found for any of the isokinetic measurements. The ET, RT, and CT groups demonstrated significant improvements in leg press (20.4, 40.8, and 39.4%) and bench press (7.5, 30.5 and 21.2%) 1 RM. RT and CT 1 RM improvements were similar and significantly greater than the ET group. Only the RT group significantly increased power. No group showed a significant change in vertical jump or 40-yard dash time. Conclusions: Findings indicate that endurance training does not interfere with strength development, but resistance training appears to hinder development of maximal aerobic capacity.

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