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Tesi sul tema "Resistance"
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1
Börjesson, Stefan. "Antibiotic Resistance in Wastewater : Methicillin-resistant Staphylococcus aureus (MRSA)and antibiotic resistance genes". Doctoral thesis, Linköpings universitet, Medicinsk mikrobiologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17709.
Testo completoAbstract (sommario):
A large part of the antibiotics consumed ends up in wastewater, and in the wastewater the antibiotics may exert selective pressure for or maintain resistance among microorganisms. Antibiotic resistant bacteria and genes encoding antibiotic resistance are commonly detected in wastewater, often at higher rates and concentrations compared to surface water. Wastewater can also provide favourable conditions for the growth of a diverse bacterial community, which constitutes a basis for the selection and spread of antibiotic resistance. Therefore, wastewater treatment plants have been suggested to play a role in the dissemination and development of antibiotic resistant bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) is a large problem worldwide as a nosocomial pathogen, but knowledge is limited about occurrence in non-clinical environments, such as wastewater, and what role wastewater plays in dissemination and development of MRSA. In this thesis we investigated the occurrence of MRSA in a full-scale wastewater treatment plant (WWTP). We also investigated the concentration of genes encoding resistance to aminoglycosides (aac(6’)-Ie+aph(2’’)), β-lactam antibiotics (mecA) and tetracyclines (tetA and tetB) in three wastewater-associated environments: (1) soil from an overland flow area treating landfill leachates, (2) biofilm from a municipal wastewater treatment plant, and (3) sludge from a hospital wastewater pipeline. In addition, concentrations of mecA, tetA and tetB were investigated over the treatment process in the WWTP. These investigations were performed to determine how the prevalence and concentration of MRSA and the antibiotic resistence genes are affected in wastewater and wastewater treatment processes over time. The occurrence of MRSA was investigated by cultivation and a commercially available real-time PCR assay. In order to determine concentrations of the genes aac(6’)-Ie+aph(2’’), mecA, tetA and tetB in wastewater we developed a LUXTM real-time PCR assay for each gene. Using cultivation and real-time PCR we could for the first time describe the occurrence of MRSA in wastewater and show that it had a stable occurrence over time in a WWTP. MRSA could mainly be detected in the early treatment steps in the WWTP, and the wastewater treatment process reduced the number and diversity of cultivated MRSA. However, our results also indicate that the treatment process selects for strains with more extensive resistance and possibly higher virulence. The isolated wastewater MRSA strains were shown to have a close genetic relationship to clinical isolates, and no specific wastewater lineages could be detected, indicating that they are a reflection of carriage in the community. Taken together, these data indicate that wastewater may be a potential reservoir for MRSA and that MRSA are more prevalent in wastewater than was previously thought. The real-time PCR assays, for aac(6’)-Ie+aph(2’’), mecA, tetA, and tetB that we developed, were shown to be sensitive, fast, and reproducible methods for detection and quantification of these genes in wastewater environments. The highest concentrations of all genes were observed in the hospital pipeline, and the lowest in the overland flow system, with tetA and aac(6´)-Ie+aph(2´´) detected in all three environments. In the full-scale WWTP, we continuously detected mecA, tetA and tetB over the treatment process and over time. In addition, it was shown that the treatment process reduces concentrations of all three genes. The data presented in this thesis also indicate that the reduction for all three genes may be connected to the removal of biomass, and in the reduction of tetA and tetB, sedimentation and precipitation appear to play an important role.
2
OUNNOUGHENE, MARC Kahn Jean-Pierre. "LA DEPRESSION RESISTANTE QUELS TRAITEMENTS POUR QUELLE RESISTANCE ? /". [S.l.] : [s.n.], 2000. http://www.scd.uhp-nancy.fr/docnum/SCDMED_T_2000_OUNNOUGHENE_MARC.pdf.
Testo completo
3
Pfeltz, Richard F. Wilkinson Brian J. "The effects of vancomycin resistance selection and magnesium on resistance expression in methicillin-resistant Staphylococcus aureus". Normal, Ill. Illinois State University, 1999. http://wwwlib.umi.com/cr/ilstu/fullcit?p9927774.
Testo completoAbstract (sommario):
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.
4
Butler, C. A. "Mechanisms of steroid resistance in therapy resistant asthma". Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546017.
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5
Maffeis, Laura <1981>. "Correlation between insulin resistance and treatment-resistant acne". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5654/1/maffeis_laura_tesi.pdf.
Testo completoAbstract (sommario):
Physiologically during puberty and adolescence, when juvenile acne usually appears, the response to a glucose load is increased if compared to the one observed in adult and at pre-pubertal age, while insulin sensitivity is reduced. Insulin is a hormone that acts at different levels along the axis which controls the sex hormones. It increases the release of LH and FSH by pituitary gland, stimulates the synthesis of androgens in the gonads and stimulates the synthesis of androgenic precursors in adrenal glands. Finally, it acts in the liver by inhibiting the synthesis of Sex Hormone Binding Globulin (SHBG). Insulin is also able to act directly on the production of sebum and amplify the effects of Iinsulin Growth Factor-1 in the skin, inhibiting the synthesis of its binding protein (IGF Binding Protein-1).
In female subjects with acne and Polycystic Ovary Syndrome (PCOS) insulin resistance is a well known pathogenetic factor, while the relationship between acne and insulin resistance has been poorly investigated in males so far.
The purpose of this study is to investigate the correlation between insulin resistance and acne in young males who do not respond to common therapies. Clinical and biochemical parameters of glucose, lipid metabolism, androgens and IGF-1 were evaluated. Insulin resistance was estimated by Homeostasis Model assessment (HOMA-IR) and Oral Glucose Tolerance Test was also performed. We found that subjects with acne had higher Sistolic and Diastolic Blood Pressure, Waist/Hip Ratio, Waist Circumference, 120' OGTT serum insulin and serum IGF-1 and lower HDL-cholesterol than subjects of comparable age and gender without acne.
The results thus obtained confirmed what other authors have recently reported about a metabolic imbalance in young males with acne. Furthermore, these results support the hypothesis that insulin resistance might play an important role in the pathogenesis of treatment-resistant acne in males.
6
Maffeis, Laura <1981>. "Correlation between insulin resistance and treatment-resistant acne". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5654/.
Testo completoAbstract (sommario):
Physiologically during puberty and adolescence, when juvenile acne usually appears, the response to a glucose load is increased if compared to the one observed in adult and at pre-pubertal age, while insulin sensitivity is reduced. Insulin is a hormone that acts at different levels along the axis which controls the sex hormones. It increases the release of LH and FSH by pituitary gland, stimulates the synthesis of androgens in the gonads and stimulates the synthesis of androgenic precursors in adrenal glands. Finally, it acts in the liver by inhibiting the synthesis of Sex Hormone Binding Globulin (SHBG). Insulin is also able to act directly on the production of sebum and amplify the effects of Iinsulin Growth Factor-1 in the skin, inhibiting the synthesis of its binding protein (IGF Binding Protein-1).
In female subjects with acne and Polycystic Ovary Syndrome (PCOS) insulin resistance is a well known pathogenetic factor, while the relationship between acne and insulin resistance has been poorly investigated in males so far.
The purpose of this study is to investigate the correlation between insulin resistance and acne in young males who do not respond to common therapies. Clinical and biochemical parameters of glucose, lipid metabolism, androgens and IGF-1 were evaluated. Insulin resistance was estimated by Homeostasis Model assessment (HOMA-IR) and Oral Glucose Tolerance Test was also performed. We found that subjects with acne had higher Sistolic and Diastolic Blood Pressure, Waist/Hip Ratio, Waist Circumference, 120' OGTT serum insulin and serum IGF-1 and lower HDL-cholesterol than subjects of comparable age and gender without acne.
The results thus obtained confirmed what other authors have recently reported about a metabolic imbalance in young males with acne. Furthermore, these results support the hypothesis that insulin resistance might play an important role in the pathogenesis of treatment-resistant acne in males.
7
Barnawi, Ibrahim. "Mechanisms of apoptosis resistance in chemotherapy-resistant cancer cells". Thesis, University of Reading, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627931.
Testo completoAbstract (sommario):
Most chemotherapy drugs work through the induction of apoptosis in tumour cells. Mutations in apoptotic pathways, notably p53 and Bcl-2, are common in cancer and associated with increased resistance to apoptosis and therefore to chemotherapy. The sensitivity of two types of cells have been compared, A 172 human glioblastoma cells and MDA-MB-23l human breast cancer cells, for their sensitivity to the chemotherapy drugs cisplatin, doxorubicin, gemcitabine, vincristine and temozolomide. Data shows that there were differences in the sensitivity of breast cancer and glioma cells to a variety of chemotherapy drugs. There were differences in nitric oxide synthase (NOS) expression between the two different types of cancer cells and yet a role was not observed for nitric oxide in changing the expression of the Bcl-2 family of proteins (both pro- or antiapoptotic). Additionally, NOS expression changed following treatment with chemotherapy drugs, suggesting that this may be the mechanism by which the cells become resistant.
8
Pelfrey, Clara Mackenzie. "Genetic resistance to experimental autoimmune encephalomyelitis : analysis of the resistance mechanisms in the Lewis resistant or LeR rat /". The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu148759742413614.
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9
Cornick, Jen. "Roadmap to resistance : antimicrobial resistance in Malawian pneumococci". Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/11173/.
Testo completoAbstract (sommario):
Multi-drug resistant (MDR) Streptococcus pneumoniae are a major public health concern worldwide. In Malawi a resource poor country, even the simplest antimicrobials remain a precious commodity. Given the limited number of antimicrobials available for the management of MDR invasive pneumococcal disease (IPD) measures need to be implemented to limit the spread of resistance. In order to design such measures it is essential that we gain a better understanding of the evolution of antimicrobial resistance in this setting. The purpose of this thesis was to assess the molecular basis and mode of dissemination of antimicrobial resistance in S. pneumoniae with the aim of identifying a biomarker of antimicrobial resistance that could be used to design a diagnostic PCR to assist epidemiological surveillance of antimicrobial resistance and inform treatment policy. Malawi introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in 2011. To provide baseline data to assess the impact of PCV13 all invasive pneumococci isolated from children admitted to Queen Elizabeth Central Hospital, Malawi 2004-2006 were serotyped and subjected to antimicrobial susceptibility testing. The data suggested PCV13 will not provide protection against 61% of penicillin resistant pneumococci and if serotype replacement occurs following the introduction of PCV13, the incidence of penicillin resistant IPD could therefore increase Over 130 resistant and susceptible pneumococcal isolates from carriage and invasive disease were subjected to whole genome sequencing. The employment of an in vitro and in silco analytical approach established that S. pneumoniae employs a diverse array of antimicrobial resistance mechanisms, the dissemination of which is likely to be driven by high antimicrobial consumption. A relatively high incidence of antimicrobial resistant was observed in serotype 1 pneumococci, the most common cause of IPD in Malawi. This serotype is not usually associated with resistance in other geographic locations, the short duration of serotype 1 carriage is assumed to limit the chance it has to acquire resistance mechanisms via recombination. Interestingly the resistance mechanisms employed by serotype 1 had been acquired through multiple recombination events. Recombination was evidenced to contribute to >90% of the variation in the serotype 1 genomes. To allow the identification of resistance biomarkers free from any preconceptions about which genes are involved in resistance, multiple antimicrobial resistant lineages were generated in vitro. Isolates were sequenced at several time points as resistance developed. Comparison of the resistant isolates to the wild type isolates identified single nucleotide polymorphisms in 46 genes, 40 of these genes have not previously been implicated in antimicrobial resistance. The role of these genes in resistance warrants further investigation. The analysis suggests that rather than a single biomarker future research needs to identify multiple biomarkers; the dynamic nature of this organism means that it can adopt one of many routes to antimicrobial resistance.
10
Chung, Whasun Oh. "Macrolide resistance and its linkage to tetracycline resistance /". Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/9279.
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11
Erkal, Hakan, e Sinan Kebapci. "Resistance to Change : A Constructive Approach for Managing Resistant Behaviors". Thesis, University of Kalmar, Baltic Business School, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hik:diva-1813.
Testo completoAbstract (sommario):
This study aims to understand, describe, and analyze the factors that lead employees resist organizational change efforts. More specifically, by locating various types of roots and symptoms of resistance, we have developed a framework which managers or individuals, who plan to initiate a change program, can use to manage resistance and to benefit, if exist, from the constructive value of resistant behaviors of employees. Findings are drawn from the reinterpretation of two case studies which were conducted on the area. While the first one involves introduction of activity-based costing system in a Portuguese telecommunications company, second one analyzes implementation of a new management program, called BATON, in a university funded research organization. By relying on these case studies, existing models and concepts related to resistance were tested, reinterpreted and an alternative framework to manage resistance is developed. As a result of the study, it is found that despite the amount of theoretical concepts and tools, there is still an important deficiency in terms of resistance management, and managers usually tend to employ pre-set methods to overcome resistance in change management. Findings of the thesis provide those who plan to start and implement change programs with a comprehensive framework to locate, understand and analyze resistance and to take appropriate managerial actions in organizational change efforts.
12
Suarez, Rachel. "Chemical disinfectant resistance in multiple antibiotic resistant and susceptible bacteria". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ57585.pdf.
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13
Bellamy, William Tracey. "Mechanisms of doxorubicin resistance in multidrug resistant human myeloma cells". Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184448.
Testo completoAbstract (sommario):
Multidrug resistance is a phenomenon associated with the emergence of simultaneous cross-resistance to the cytotoxic actions of a wide variety of structurally and functionally unrelated antineoplastic agents. One of the agents to which cross-resistance is commonly observed is doxorubicin, a commonly used antineoplastic. Studies were undertaken to determine the mechanism of doxorubicin resistance in multidrug resistant 8226 human myeloma cells. When sensitive and resistant cells were exposed to the same extracellular concentration of doxorubicin there was a decrease in the quantity of DNA lesions in the resistant subline which corresponded to a decrease in doxorubicin accumulation. When the extracellular concentration of drug was adjusted to yield equivalent intracellular levels these differences were removed. Studies utilizing an isolated nuclei system revealed no differences in the formation of DNA lesions between the sensitive and resistant cells when exposed to the same concentration of drug. Studies were undertaken to determine if the resistant subline had an increased capacity to detoxify doxorubicin via glutathione-based enzyme systems. The activities of glutathione-s-transferase and glutathione peroxidase were not found to be elevated in the resistant subline. There was a significant elevation in the nonprotein sulfhydryl content of the resistant cells as compared to the drug-sensitive line. This elevation was unstable in the absence of doxorubicin, displaying a steady decline until reaching baseline levels found in the sensitive cells. The decrease in NPSH content in the resistant line was not accompanied by an alteration in doxorubicin resistance. Thus, it appears that glutathione-based enzymatic detoxification is not causally related to doxorubicin resistance in 8226 human myeloma cells. Verapamil, an agent shown by previous studies to modulate doxorubicin resistance, led to an increase in the formation of doxorubicin-induced DNA lesions in the resistant cells secondary to an increase in intracellular drug accumulation. It had no effect on doxorubicin-induced DNA lesions or drug accumulation in the sensitive cells. Verapamil thus appears to be reversing doxorubicin resistance by increasing drug accumulation and thereby enhancing DNA damage. Under these circumstances there was a good correlation between doxorubicin accumulation, DNA damage, and cytotoxicity in the 8226 cells. The conclusion is drawn that drug accumulation accounts for the majority of doxorubicin resistance in the 8226 human myeloma cell line.
14
McGhee, Derek Peter. "Passing resistance". Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302368.
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15
Wainwright, Britny L. "Floral Resistance". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492431415778475.
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16
Eakle, Elaina Helene. "Organizing resistance: Resistance and identity in student activist coalitions". Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1564676169027417.
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17
Reed, Scott Gregory. "Webs of resistance new media, ecocomposition, and resistance theory /". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001114.
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18
Stordal, Britta Kristina. "Regrowth resistance in platinum-drug resistant small cell lung cancer cells". Bill Walsh Cancer Research Laboratories, Royal North Shore Hospital and The University of Sydney, 2007. http://hdl.handle.net/2123/2467.
Testo completoAbstract (sommario):
Doctor of Philosophy (PhD)The H69CIS200 cisplatin-resistant and H69OX400 oxaliplatin-resistant cell lines developed as part of this study, are novel models of low-level platinum resistance. These resistant cell lines do not have common mechanisms of platinum resistance such as increased expression of glutathione or decreased platinum accumulation. Rather, these cell lines have alterations in their cell cycle allowing them to proliferate rapidly post drug treatment in a process known as ‘regrowth resistance’. This alteration in cell cycle control has come at the expense of DNA repair capacity. The resistant cell lines show a decrease in nucleotide excision repair and homologous recombination repair, the reverse of what is normally associated with platinum resistance. The alterations in these DNA repair pathways help signal the G1/S checkpoint to allow the cell cycle to progress despite the presence of DNA damage. The decrease in DNA repair capacity has also contributed to the development of chromosomal alterations in the resistant cell lines. Similarities in chromosomal change between the two platinum resistant cell lines have been attributed to inherent vulnerabilities in the parental H69 cells rather than part of the mechanism of resistance. The H69CIS200 and H69OX400 resistant cells are cross-resistant to both cisplatin and oxaliplatin. This demonstrates that oxaliplatin does not have increased activity in low-level cisplatin-resistant cancer. Oxaliplatin resistance also developed more rapidly than cisplatin resistance suggesting that oxaliplatin may be less effective than cisplatin in the treatment of SCLC. The resistant cell lines have also become hypersensitive to taxol but show no alterations in the expression, polymerisation or morphology of tubulin. Rather, the PI3K/Akt/mTOR pathway is involved in both platinum resistance and taxol sensitivity as both are reversed with rapamycin treatment. mTOR is also phosphorylated in the resistant cell lines indicating that platinum resistance is associated with an increase in activity of this pathway. The mechanism of regrowth resistance in the platinum-resistant H69CIS200 and H69OX400 cells is a combination of activation of PI3K/Akt/mTOR signalling and alterations in control of the G1/S cell cycle checkpoint. However, more work remains to determine which factors in these pathways are governing this novel mechanism of platinum resistance.
19
Siu, Tin-po Jacky, e 蕭天保. "Vancomycin heteto-resistance in blood isolates of methicillin-resistant Staphylococcus aureus". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46632153.
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20
Iwakami, Satoshi. "Molecular mechanism of resistance in a multiple-herbicide resistant Echinochloa phyllopogon". Kyoto University, 2013. http://hdl.handle.net/2433/180368.
Testo completoAbstract (sommario):
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第17830号
農博第2015号
新制||農||1016(附属図書館)
学位論文||H25||N4787(農学部図書室)
30645
京都大学大学院農学研究科農学専攻
(主査)教授 稲村 達也, 教授 冨永 達, 教授 奥本 裕
学位規則第4条第1項該当
21
Stordal, Britta. "Regrowth resistance in platinum-drug resistant small cell lung cancer cells". Connect to full text, 2006. http://hdl.handle.net/2123/2467.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of Sydney, 2007.Title from title screen (viewed 10 June 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Medicine, Faculty of Medicine. Degree awarded 2007; thesis submitted 2006. Includes bibliographical references. Also available in print form.
22
Awsumb, Clay Michael. "Subject of Resistance| Conceptualizing "Culture" and "Resistance" in Social Theory". Thesis, Southern Illinois University at Edwardsville, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10147080.
Testo completoAbstract (sommario):
In this study I approach the contradictory, contentious, and competing notions of resistance as a conceptual problem, with empirical discursive realities, limiting social researchers’ ability to understand relations of power and culture. Using a grounded methodological, I conduct meta-analyses of theoretical, conceptual, and empirical literatures on and/or employing the concepts resistance, culture, and power. From this data, I present a series of emergent epistemic themes as epistemorphs, or knowledge forms, that order a “structure for knowing” characteristic of each term's constitution. I then develop a series of deconstructive analyses aimed at the external validity/reliability and intensional logics of each discursively identified conceptualization structure. I identify in these analyses a series problematics for the intensional logics ordering these concepts. In light of these findings and analyses, I introduce a number of new concepts as an alternative structure for knowing. I conceptualize power in terms of: power (an agent’s properties with capacities to apply force and accomplish things), fortepovon (the praxis of agentic powers), and efikepotenco (the efficacy of powers realized). I introduce a conceptual distinction between ‘the cultural’ (the Discursive mediation of culture) and ‘culture’ (a process of knowledge formation in which experience is made intelligible and comprehensible). In relation the distinction for culture, I introduce a dialectic elaboration of Foucault’s concept of power/knowledge: povonscio (powers in knowledge) and superfortiscio (power determinate knowledge). Returning to the conceptual questions concerning resistance, I articulate a dialectic conceptual formation for resistance and domination as dimensions of fortepovon, rather than being separate and independent phenomena. As an alternative, I propose conceptualizing the praxis of powers as either "oppressive" or "liberating."
23
Syamsuar, Dedy. "Understanding IPv6 resistance: A model of resistance among Indonesian organizations". Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/1195.
Testo completoAbstract (sommario):
Since its inception in the 1970s, the Internet’s underlying protocol, IPv4, has been incredibly successful; however, the massive and unanticipated growth of the Internet has revealed its limitations. IPv6 was developed as a solution, but despite having many technological improvements its adoption remains very rare. This research examines organizational resistance to IPv6 and proposes an IPv6 Resistance Model which has been developed, empirically tested and validated in the context of Indonesian organizations.
24
Prodromou, M. "Writing, Event, Resistance". Thesis, University of Essex, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485494.
Testo completoAbstract (sommario):
This thesis provides a reading of Jean-Franc;ois Lyotard's thoughts on the relationship between writing, the event, and resistance. My argument is that for Lyotard, writing has a responsibility to inscribe in the writing itself what resists thinking and as such, to articulate the inarticulable. Chapter 2 traces how this responsibility arises with the receptivity and affirmation of an unconditional imperative(Understood in this context, writing is the performative response to an ethical demand or event of obligation to which it bears witness. The thesis illuminates how Lyotard articulates the event as a receptivity to alterity through his readings of Kant's theory of obligation (Chapter 2) and Freud's thoughts on trauma and the unconscious affect (Chapter 3). One of the main tasks of the thesis is to show how the task of bearing witness - the political task par excellence for Lyotard - necessitates the use of reflective judgment (judgment without rules). I explore this task through a delineation of Lyotard's readings of the Kantian sublime (Chapter 2) and the task of perlaboration in psychoanalysis (Chapter 3). These discussions are framed within the context of Lyotard's . diagnosis of the failure of the grand narratives of modernity and as such, within the problematic of responding to nihilism. Finally, Chapter 4 is an attempt to recommence a dialogue between Lyotard and Nietzsche that is motivated by the former's Heideggerian reading of the latter in The Inhuman, to which this chapter responds. The aim is to show how their thoughts intersect and supplement one another in their respective diagnoses of nihilism but also in their attempt to write the event and bear witness to that which resists thinking. My argument is that Nietzsclie's theory of the event is inscribed in the thought of eternal return which establishes an ethical resonance to the diagnosis of the death of god.
25
Hall, R. J. "Modelling fungicide resistance". Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599864.
Testo completoAbstract (sommario):
Fungicide resistance, whereby a mutation conferring reduced sensitivity to chemical control arises and spreads through a fungal population, severely inhibits the successful control of crop disease. Mathematical models play a vital role in assessing the risk of invasion of fungicide-resistant pathogens, and in the design of effective resistance management strategies. In this thesis, I investigate the factors affecting the invasion of resistance in heterogeneous crop environments. I develop a simple, nonlinear model for fungicide resistance which, improving on existing work, incorporates the dynamics of the host crop and quantities how the amount, decay and timing of a fungicide dose affect selection for resistance. The model structure is similar to those used to describe antibiotic resistance, and hence much of the analysis presented here applies more generally to drug and pesticide resistance. I identify a threshold for the invasion of resistance in terms of two key parameters, both of which are amenable to estimation in the field. These are the fitness of the resistant strain relative to the wild-type, and treatment efficacy (which summarises how control inhibits pathogen survival and reproduction). Using a discrete, stochastic formulation of the model, I demonstrate that this threshold is robust to the effects of demographic stochasticity, and estimate the probabilities of resistance pre-existing or emerging during treatment. In the final section of the thesis, I extend the simple model to examine the dynamics of multiple pathogen strains, the effects of seasonal disturbance to the host (through planting and harvesting) on persistence of the resistant pathogen, and how the scale of pathogen dispersal affects the spatial propagation of resistance.
26
Cramer, Jacob M. "Strategies of Resistance". Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/593600.
Testo completoAbstract (sommario):
Political resistance is manifested in a variety of ways, including violent and nonviolent methods. Though violence and nonviolence are often treated as analytically distinct phenomena, this dissertation argues that there is value in understanding how the methods are related, and how underlying factors lead to the use of one over the other. There are many resistance groups which use a combination of both violent and nonviolent tactics, and only by examining these methods in conjunction with one another can we more fully understand their use. To understand the efficacy of jointly examining violent and nonviolent tactics, this dissertation addresses the topic from three primary perspectives. The introductory chapter offers the primary questions and puzzles this dissertation will explore. Following that, chapter two, is the first primary perspective to be addressed: the individual level. The arguments in chapter two revolve around personal networks, and the characteristics of those networks that impact views on the use of nonviolence by violent groups. Chapter three takes a state and environmental perspective, and identifies factors unique to the state and their impact on the likelihood of violence and nonviolence. Chapter four examines organizations as the unit of analysis, and inter-organizational characteristics are assessed for their impact on the use of nonviolence by violent groups. The concluding chapter brings together the insights gained from the empirical chapters, and offers suggestions for future efforts. Overall, I find that violent and nonviolent tactics share underlying correlates that impact their use, and that their joint examination offers insights on group behavior otherwise unavailable. A unified approach to the range of conflict methods offers new insight and understanding to conflict and conflict processes.
27
Jhaveri, Nynika (Nynika P. ). "Gardens of resistance". Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/132765.
Testo completoAbstract (sommario):
Thesis: M. Arch., Massachusetts Institute of Technology, Department of Architecture, February, 2021Cataloged from the official pdf of thesis.
Includes bibliographical references (pages 158-159).
Over the last few millennia, the city that today is the seat to the world's largest "democracy" has served as the nerve center for generations of empires and emperors, political paradigms and intersecting identities. As for most capital cities such as New Delhi, alongside entrenched political regimes come the evolution of a parallel legacy of fighting against, opposing and obstructing, and resisting. Whether manifesting as the rallying cries at mass protests, as the purposeful strokes on canvas in practices of critical art, or as the defiant lyrics and rhythms in musical compositions, resistance is instrumental in the vocabulary of any effective political vision. Considering the Central Vista Complex in Lutyens' New Delhi specifically, we look at a political urban fabric that has embodied these simultaneous histories for the past century, as a site of power and of resistance to that same power, as belonging to the governing and to the governed. Built as a monumental colonial project in opposition to Delhi's existing Mughal city center in 1911, appropriated as a symbol of a new nation's power as a post colonial inversion in 1947, serving as a site for rallies, protests, and parades engaging the growing pains of independence and modernization in 60s and 70s, and finally as part of a repressive, autocratic re-branding resisting due process and dialogue in 2020, the site's spatial politics have also witnessed a plethora of resistances. This thesis questions the role of architecture in envisioning and engaging the tools of resistance in the context of such political sites. It narrates the stories of three actors as they reclaim the Complex's Mughal Gardens - landscapes historically seen as spaces of utopic experimentation and speculation - as spaces of their own resistance. Considering the architectural tools of process, scale, materiality, and temporality, the actors strive to re-inscribe an entirely new set of contemporary cultural and civic values into an otherwise charged landscape, a form of socio-spatial resistance in response to their own historical moments.
by Nynika Jhaveri.
M. Arch.
M.Arch. Massachusetts Institute of Technology, Department of Architecture
28
Wilson, F. D., e H. M. Flint. "Host Plant Resistance". College of Agriculture, University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/203923.
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29
Wilson, F. D., e H. M. Flint. "Host Plant Resistance". College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/219754.
Testo completoAbstract (sommario):
The 1985 and 1986 Cotton Reports have the same publication and P-Series numbers.Cotton breeding stocks were evaluated for resistance to pink bollworm. Resistance is being transferred into improved agronomic stocks.
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Wiechmann, Juria C. "Pedagogies of Resistance". Thesis, Minot State University, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13425660.
Testo completoAbstract (sommario):
Many teachers describe teaching as a vocation. Similar to a priest, rabbi, imam, nun or monk, a teacher may feel morally justified to break policy or go against curriculum that they feel is immoral or oppressive. The purpose of this study is to explore the ways in which teachers resist or rebel in their classrooms when the policies or curriculum go against their beliefs. Furthermore, I aim to understand the implications of their resistance or rebellion. This study’s findings are taken from observations and interviews with two elementary teachers. The results demonstrate that in order to help their students succeed, teachers may work around or silently disobey policy and curriculum. As this study highlights, the impact of resistance or rebellion is felt in different ways by schools, teachers, and students.
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Francisco, Dayane Evellin de Souza. "Voices of resistance". reponame:Repositório Institucional da UFSC, 2016. https://repositorio.ufsc.br/xmlui/handle/123456789/167789.
Testo completoAbstract (sommario):
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Inglês: Estudos Linguísticos e Literários, Florianópolis, 2016.Made available in DSpace on 2016-09-20T04:20:35Z (GMT). No. of bitstreams: 1 340836.pdf: 918485 bytes, checksum: bac4d7bb08e8e3ff5913ff68ecc0de23 (MD5) Previous issue date: 2016
Abstract : This research addresses the issues of intersectionality and agency in Maya Angelou?s autobiographical work I Know Why the Caged Bird Sings. The specific objective of this investigation is to analyze the metaphor of the ?caged bird?. In order to conduct such analysis, this research draws on the concept of ?intersectionality? coined by Kimberlé Crenshaw to investigate how different stratifying factors?such as race, gender and class ? intersect in creating the experience of black women. In addition, this work focuses on Judith Butler?s concept of ?agency? in order to investigate whether signs of resistance can be perceived in the narrative regardless of the social structures the characters are part of. This research indicates that, although the characters in Caged Bird are constrained by different modes of oppression, they find within these social structures spaces for exercising agency. The protagonist and the different characters the narrator describes are caged by race, poverty, gender, just to mention a few. Nevertheless, in the same way that ?caged birds? sing, they are also able to express some form of creative resistance.
Esta pesquisa aborda as questões de interseccionalidade e agência na narrativa autobiográfica da escritora Afro-Americana Maya Angelou, intitulado Eu Sei Porque o Pássaro Canta na Gaiola. O objetivo específico dessa investigação é analisar a metáfora do ?pássaro engaiolado?. Para a realização de tal análise, esta pesquisa baseia-se no conceito de ?interseccionalidade?, cunhado pela primeira vez por Kimberlé Crenshaw com o intuito de investigar como diferentes fatores ? como, por exemplo, raça, gênero e classe ? intersectam na criação da mulher negra. Além disso, o trabalho utiliza-se do conceito de ?agência?, tal como entendido por Judith Butler, a fim de investigar se sinais de resistência podem ser encontrados no romance independentemente das estruturas sociais em que os personagens estão inseridos. Esta pesquisa indica que, embora as personagens sejam restringidas por diferentes formas de opressão, elas encontram dentro das estruturas sociais espaço para exercer sua agência. A protagonista, bem como as diferentes personagens descritas por ela, são engaioladas por sua raça, gênero e class, etc. No entanto, assim como o ?pássaro engaiolado? canta, elas também são capazes de expressar algumas formas de resistência criativa.
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Pierce, Kyle R., Clive Brewer, Michael W. Ramsey, Ronald Byrd, William A. Sands, Margaret E. Stone e Michael H. Stone. "Youth Resistance Training". Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etsu-works/4140.
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Rusin, Patricia Anne. "Antibiotic resistance, heavy metal resistance, chlorine resistance and phage typing patterns of fecal coliforms isolated from secondary effluent". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184925.
Testo completoAbstract (sommario):
Antibiotic resistance profiles of fecal coliform isolated from unchlorinated and chlorinated secondary effluent were determined. Of 332 fecal coliforms isolated from chlorinated effluent a mean of 48% were multiply antibiotic resistant. In contrast, of 347 fecal coliforms isolated from unchlorinated effluent a mean of 29% were multiply antibiotic resistant. Resistance to ampicillin, cephalothin, and carbenicillin were significantly higher in the former than the latter. Randomly selected isolates survived and/or grew in sterile and unsterile effluent retaining resistance patterns for 40 days. Resistance factors were transferred in laboratory medium at frequencies from 0 to 1.2 x 10⁻² (number of recombinants/number of recipients) and in sterile neutralized tertiary effluent at frequencies from 0 to 1.0 x 10⁻⁴. Resuscitative techniques were necessary for optimal recovery of fecal coliforms from effluent using selective media. Antibiotic resistance patterns of fecal coliforms isolated from unchlorinated and chlorinated effluent was not associated with chlorine or heavy metal resistance. Multiply antibiotic resistant fecal coliforms from chlorinated effluent were significantly less sensitive to lytic phage than multiply antibiotic sensitive fecal coliforms from unchlorinated effluent (p < .05). Using group discriminate analysis of data, phage typing techniques were shown to be a potential tool for tracing fecal contamination of groundwater.
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Ko, Wai-ting, e 高慧婷. "Molecular characterization of pyrazinamide resistance in Mycobacterium tuberculosis". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/193536.
Testo completoAbstract (sommario):
Tuberculosis (TB) is a highly infectious disease that causes the second highest mortality rate in human worldwide. The emergence of multi-drug resistance tuberculosis (MDR-TB) leads to a major public health problem in controlling TB-caused mortality. Pyrazinamide (PZA) is an important first-line drug in the treatment of MDR-TB. However, since the challenge in performing susceptibility test on PZA, World Health Organization has not published any data on the prevalence of PZA resistance in Mycobacterium tuberculosis (M. tuberculosis). Since the occurrence of PZA resistance makes MDR-TB more difficult to treat with poor prognosis, rapid detection method in PZA resistance is urgently needed. Since pncA mutation is highly associated with up to 98% PZA resistant M. tuberculosis strains, it is worthwhile to develop rapid molecular method for detecting PZA resistance. This study aims to identify the mutations in PZA resistant M. tuberculosis strains.
The first part of this study aims to characterize the pattern of pncA mutation among PZA-resistant and PZA-susceptible M. tuberculosis using Sanger sequencing method. Among all clinical isolates, 12 out of 29 cases of M. tuberculosis were resistant to PZA. All PZA-resistant M. tuberculosis strains harbored pncA mutation, whereas no known mutations were found among those PZA-susceptible strains, giving the positive predictive value to be 100%. Eight mutation patterns were found among 12 resistant isolates. Four of these pncA mutations have not been described previously by other studies. Study also characterizes the pattern of pncA mutation in 19 sputum specimens, with 2 mutation patterns found. Overall 10 mutation patterns were found in this study. Results show that the mutation of pncA gene is highly associated with PZA-resistant M. tuberculosis. Results also suggest the scattered and more extensive mutations in pncA gene that confer PZA resistance to M. tuberculosis.
The second and the last part of this study aims to evaluate the possibility of using molecular method to detect PZA resistance in routine clinical laboratory. Results show that using molecular sequencing to detect PZA resistance can shorten the turnaround time to about 3-4 working days. Since mutation of pncA was scattered along the entire pncA gene, using DNA sequencing approach may be the best strategy for the rapid detection of PZA resistance in M. tuberculosis.published_or_final_version
Medical Sciences
Master
Master of Medical Sciences
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Wan, Zhon Gli, Hidetoshi Kobayashi, Akemi Hayakawa e Takeo Ishigaki. "A Diffusible Resistance Factor(s) in Spontaneous Mitomycin Resistant Mammalian Cancer Cells". 名古屋大学医学部, 1998. http://hdl.handle.net/2237/6193.
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Fleeman, Renee. "Discovering Antibacterial and Anti-Resistance Agents Targeting Multi-Drug Resistant ESKAPE Pathogens". Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6839.
Testo completoAbstract (sommario):
Antibiotic resistance has been a developing problem for mankind in recent decades and multi-drug resistant bacteria are now encountered that are resistant to all treatment options available. In 2014, the World Health Organization announced that this problem is driving us towards a “post-antibiotic era” that will change the face of modern medicine as we know it. If lack of novel antibiotic development and FDA approval continues, by the year 2050, 10 million people will die each year to an antimicrobial resistant bacterial infection. With lack of pharmaceutical industry involvement in developing novel antibiotics, the responsibility now lies within the academic institutions to identify potential novel therapeutics to fuel the antibiotic drug discovery pipeline. Combinatorial chemistry is one technique used to expedite the discovery process by assessing a large chemical space in a relatively short time when compared to traditional screening approaches. Combinatorial libraries can be screened using multiple approaches and has shown successful application towards many disease states. We initially discovered broad spectrum antibacterial bis-cyclic guanidines using combinatorial libraries and expanded on the knowledge of the physiochemical attributes necessary to inhibit Gram negative bacterial pathogens. Following this success, we continued to assess the combinatorial libraries for adjunctive therapeutics that potentiate the activity of obsolete clinical antibiotics. The polyamine efflux pump inhibitors discovered in this subsequent study prove the benefits of using the large chemical space provided in the combinatorial libraries to identify a variety of therapeutics. Our studies always begin with identifying an active compound and active compounds undergo hit-to-lead optimization. This optimization studies are of utmost importance in developing a novel antibacterial agent for therapeutic applications. Our medicinal chemistry work described here is proof of the success of careful structure activity analyses to optimize a hit scaffold to create a more effective antibacterial agent. Overall, our work described here reveals the potential role of academic institutions in fending off the impending “post-antibiotic era”.
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Lopez, Miriam Dorothy. "Bt-resistant European corn borers and Nosema pyrausta implications for resistance management /". [Ames, Iowa : Iowa State University], 2008.
Cerca il testo completo
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Walker, Adrian Bernard. "The effect of insulin on resistance artery function in insulin-resistant states". Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312450.
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Davies, Sarah Elisabeth. "Development of antimicrobial resistance in Acinetobacter spp and methicillin-resistant Staphylococcus aureus". Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4388.
Testo completoAbstract (sommario):
Background: Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus (MRSA) represent the most worrying Gram-negative and Gram-positive nosocomial pathogens of the present age. They are of increasing concern in the clinical environment due to their multi-drug resistance and the dwindling therapeutic options available. A. baumannii is the most frequently isolated clinical species of the genus, and is able to rapidly acquire resistance. Hypermutators, most frequently deficient in mismatch repair (MMR) via defects in the mutS gene, have been associated with antimicrobial resistance in several bacterial populations. To date, however, the potential role of MMR-deficient mutators in the development of resistance in clinical Acinetobacter spp. has not been investigated. Biocides, most notably chlorhexidine (CHX), are increasingly used in the hospital environment to prevent bacterial spread. This has led to concerns about the development of reduced biocide susceptibility and associated antibiotic resistance in hospital bacterial populations, where there is frequent exposure to both of these factors. The effect of CHX upon defined clinical MRSA isolates is examined here. Methods: The mutS gene of clinical Acinetobacter spp. isolates with varying sensitivities was sequenced and compared to establish whether any variations were present. Mutation studies were performed on isolates by challenging them with ciprofloxacin to determine whether different mutS types correlated with any variation in their ability to develop significant fluoroquinolone resistance. The response of clinical MRSA isolates to a range of CHX concentrations was examined with susceptibility testing methods, and effects were compared with standard strains. Determination of post-exposure minimum inhibitory concentrations (MICs) of a range of antibiotics enabled evaluation of whether exposure to CHX had an effect on susceptibility to antibiotics. Results: Variation was observed in the mutS gene of clinical Acinetobacter spp. isolates, with greater homology observed as resistance increased. A highly conserved and previously unreported amino acid sequence was discovered in resistant isolates. Nonresistant isolates with this ‘R-type’ mutS sequence appeared to have a greater ability to develop significant ciprofloxacin resistance. Clinical MRSA isolates had varying susceptibility to CHX, and there were differences in the susceptibility of standard strains compared to clinical isolates. CHX residues exerted a prolonged minimal inhibitory effect, and several increases in antibiotic MICs following CHX exposure were observed. Conclusions: The correlation of the mutS sequence with mutation ability suggests that defects in the mutS gene may have a role to play in the ability of certain Acinetobacter spp. to rapidly acquire resistance. This could have implications for the treatment of Acinetobacter spp. infections, and may enable quick determination of which clinical isolates have the potential to develop clinically significant resistance. Incomplete eradication due to the prolonged minimal effect of CHX residues may act as a selective pressure in the hospital environment, allowing survival of reduced susceptibility MRSA isolates. Increases in antibiotic MICs following CHX exposure is of grave concern for the future of biocide usage.
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O'Neill, Colette. "Antibiotic-resistant staphylococci in the agricultural environment : reservoirs of resistance and infection". Thesis, University of Warwick, 2010. http://wrap.warwick.ac.uk/35767/.
Testo completoAbstract (sommario):
Antibiotic resistance is a serious problem in human and animal infections. Heavy use of antibiotics in the agricultural environment selects for antibiotic resistance among the microflora of food animals, providing a reservoir of antibiotic-resistant bacteria. These may enter the human population through the food chain or by direct contact, as demonstrated by the recent emergence of livestock-associated MRSA strains. Antibiotic resistance determinants selected in this environment may also be available for transfer to human commensals and pathogenic bacteria. Milk from conventional and organic farms was screened for methicillin-resistant staphylococci to explore the hypothesis that organic farming methods result in reduced selection for antibiotic resistance. A significantly greater number isolates from conventionally farmed milk were resistant to clindamycin, erythromycin, fusidic acid, tetracycline and tobramycin than isolates from organic milk. Isolates from organic milk mostly belonged to S. fleurettii, which does not cause any known pathogenesis or contribute to the mobile methicillin resistance reservoir. Conventional milk harboured a greater number of pathogens, including S. epidermidis and S. sciuri, both of which carried SCCmec. SCCmec elements were diverse, some similar to those found in human-associated staphylococci, and some distinct. The virulence-associated biofilm cluster icaADBC was identified in some S. epidermidis isolates, indicating increased human pathogenesis. A putative new species, S. lactis sp. nov. was isolated from a conventionally farmed herd, reflecting the high diversity of staphylococci in this environment. In pig nasal swabs originating from Thailand, LA-MRSA was identified for the first time. These isolates belonged to the ST9/t337 lineage which has been identified previously in Europe, suggesting importation of colonised pigs as the most likely route of dissemination. These contained apossible new SCCmecvariant, and harboured toxin genes associated with human disease. Isolates were resistant to medically important antibiotics including ciprofloxacin and chloramphenicol. These data support the hypothesis that use of antibiotics in agricultural practice may select for increased resistance in the microbiome of farm animals, and that some of these may be able to cause infections in humans. Early detection of MRSA is the key to effective treatment and control of dissemination; in food production this would allow early identification of contaminated meat or dairy products and prevent these from entering the food chain. The novel application of an isothermal amplification assay, LAMP, was investigated for the sensitive and specific detection of MRSA. Unfortunately, false negative reactions were common due to high variability among SCCmec subtypes, and the possession of non-mec SCC elements by methicillin-sensitive strains precluded this from offering a reliable alternative to existing methods.
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Stenhouse, Lindsay Joanne. "Characterisation of anthelmintic resistance in a multiple drug resistant Teladorsagia circumcinta isolate". Thesis, University of Glasgow, 2007. http://theses.gla.ac.uk/4251/.
Testo completoAbstract (sommario):
The purpose of this study was to undertake detailed molecular and phenotypic characterisation of a MDR isolate of T. circumcincta (MTci5) with particular focus upon the mechanisms underlying benzimidazole (BZ) resistance. MTci5 was isolated from a farm in Central Scotland, which employed a suppressive anthelmintic dosing regime and was closed in 2002 when control of the parasite population became unsustainable. Underpinning all of the experiments in this study was an anthelmintic selection process whereby the MTci5 isolate was pressured individually with three broad-spectrum anthelmintics (benzimidazole, ivermectin and levamisole). There are three main areas of investigation in this study, the first being an investigation of the population genetic structure or a MDR isolate. A central question was whether the MDR phenotype of MTci5 is conferred by the inheritance of genes present in a single interbreeding population or whether there is genetic sub-structuring, whereby discrete sub-populations of the isolate each show resistance to different anthelmintics. Microsatellite analysis was employed to investigate the population genetic structure of the MTci5 isolate. The results suggest that the MTci5 isolate is a single, freely interbreeding population with triple resistance, showing no evidence of genetic sub-structuring. The second area of investigation was the role of the F200Y isotype I ß-tubulin mutation in the determination of BZ resistance and the potential involvement of this mutation in resistance to ivermectin (IVM) and levamisole (LEV). There was no evidence of an effect of IVM or LEV selection upon the F200Y isotype I ß-tubulin mutation. The third area of investigation was the origin and diversity of BZ resistance alleles in the MTci5 isolate. Single strand conformation polymorphism (SSCP) analysis of small region extending through exons 1 and 2 and intron 1 of the isotype I ß-tubulin gene was used to assess the genetic diversity of this locus in the MTci5 isolate and of five other UK T. circumcincta populations. Results are consistent with the theory of multiple independent, spontaneous mutations at the P200 locus of the isotype I ß-tubulin gene.
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Rose, Helen Louise. "Antimicrobial resistance of CF pathogens : mechanisms of biocide resistance and action". Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54824/.
Testo completoAbstract (sommario):
Cystic fibrosis (CF) patients are predisposed to a number of bacterial infections, including
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Mazahery-Laghab, Hojjatollah. "Endogenous resistance to insect pests in alfalfa : engineering for enhanced resistance". Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4695/.
Testo completoAbstract (sommario):
Alfalfa (Medicago sativa) is a valuable forage crop grown throughout the World. While the crop is resistant to attack by many insect pests, it is subject to potentially severe losses through the action of several specific pests, which are adapted to alfalfa as a host. The most economically damaging of these pests is the alfalfa weevil, Hypera postica. This thesis investigates the endogenous defences of alfalfa against insects, which are responsible for its resistance to non-pest species, and develops a strategy for increasing the resistance of alfalfa towards pest species, specifically alfalfa weevil. The role of saponins in the resistance of alfalfa towards non-pest species has been investigated by using successive insect bioassays, carried out with extracts, mixtures of compounds, and purified compounds, to identify which compounds present in alfalfa tissues are responsible for toxicity towards insects. Crude saponin extracts, in 80% methanol, from alfalfa seedling tissues were bioassayed against the cowpea seed weevil, Callosobruchus maculatus. Both extracts from shoot and root tissues caused larval mortality and delayed development when incorporated into an artificial diet at levels comparable to those found in alfalfa, but lower levels of root saponin extracts showed probiotic effects, whereas lower levels of shoot saponins were still toxic. Hydrolysis of the saponins present in these extracts decreased their toxicity. Purified saponin mixtures were prepared by butanol partition and ether precipitation, and were bioassayed against potato aphid (Aulacorthum solani) in a liquid artificial diet, which allowed quantitative effects to be accurately assayed. Shoot saponins showed a concentration-dependent toxic effect, decreasing survival over an initial 5 day period, decreasing growth, and inhibiting fecundity (measured by nymph production) in these insects. Alfalfa root saponins showed no deleterious effects below a threshold level, but caused complete mortality above this level. The alfalfa saponin mixtures were separated into fractions by chromatography on a reverse phase column. Bioassays showed that the toxicity towards potato was associated only with fractions containing saponins, and that fractions containing a component identified as soyasaponin I were more toxic to the aphids than others. Finally, two saponins purified from alfalfa, soyasaponin I and medicoside A, were assayed. These assays showed that soyasaponin was consistently more toxic in effects on mortality, growth and fecundity. It was concluded that alfalfa saponins, and in particular soyasaponin I, were major factors in the resistance of alfalfa towards potato aphid, and other insects. A saponin mixture from another species, sugar beet {Beta vulgaris) was also toxic to aphids, supporting the view that saponins have a general role in resistance to insects. Inhibition of insect digestive proteolysis by expression of a foreign protein protease inhibitor was selected as a strategy to protect transgenic alfalfa against alfalfa weevil. The major protease activity in larvae of this msect was shown to be due to cysteine proteases, which could be inhibited by cystatins. Rice cystatin was produced in large quantity using a recombinant protein expression system in E. coli for use in a "proving" experiment. Incorporation of the rice cystatin into an alfalfa weevil larvae artificial diet decreased survival, showing that this approach was feasible.
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Nóbrega, Franklin Luzia de. "Heavy-metal resistance in Marinobacter aquaeolei 617 insights into copper resistance". Master's thesis, Faculdade de Ciências e Tecnologia, 2009. http://hdl.handle.net/10362/5924.
Testo completoAbstract (sommario):
Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em BiotecnologiaHeavy metal resistance in Marinobacter aquaeolei (Ma.aq) 617 in aerobic conditions was studied for three different ions, cadmium, cobalt and copper. The main aim of this work was the study of a putative copper resistance operon, copSRXAB, located in the chromosome of Marinobacter and the biochemical characterization of a unique copper binding protein CopX (proposed designation), associated with the copper resistance system. Growth under heavy metal ion stress was performed for those three heavy metals and the Minimum Inhibitory Concentration (MIC) / Maximum Tolerant Concentration (MTC) was determined using two different approaches, solid artificial sea water (ASW) plates and liquid ASW medium, supplemented with lactate and yeast extract, as carbon sources. The MIC/MTC of cadmium, cobalt and copper ions was found to be 200 μM, 4-6 mM, and 1.6 mM, respectively. These values classify Ma.aq strain 617 as cadmium, cobalt and copper resistant strain. Moreover, during the cobalt resistance studies we observed the production of an unknown protein or compound, which is proposed be a cobalamine containing protein and/or cobalamine itself. Under the scope of copper resistance, preliminary proteomics analysis of the Ma.aq periplasmic fraction was performed. CopX, identified by MALDI TOF-TOF mass spectrometry, was shown to be differentially expressed under copper stress. This demonstrated that the proposed copper operon, copSRXAB, has a role in the Ma.aq copper resistance. CopX was successfully heterologously expressed in Escherichia coli (Es.coli), and purified for the first time using usually two chromatographic steps (anionic exchangeand size exclusion) with a yield of 5.7 mg or 1.8 mg of purified CopX, per L of LB or M9 medium, respectively. Mass spectrometry Electron Spray Ionisation (ESI) and N-terminus analysis revealed that the signal peptide of CopX comprises 21 residues, and is efficiently processed by the Sec system of Es.coli. Biochemical characterization of CopX proved that it is a periplasmic monomeric type 1 copper protein, with a molecular weight of 17253.25 ± 0.30 Da, determined by mass spectrometry (ESI), that binds approximately 1 copper ion per polypeptide chain. The apparent molecular weight of CopX, 20.4 kDa, determined by size-exclusion chromatography does not depend on the ionic strength. Spectroscopic characterization showed that it presents an intense charge transfer (Scys – Cu ion) band at 440 nm and 580 nm and 720 nm. The extinction coefficient at 580 nm was found to be 3.8 mM-1cm-1, according to the copper content. CopX EPR spectrum is axial. The 15N HSQC NMR spectra of CopX confirms that it is folded, with 131 out of 147 backbone amide resonances identified, showing that it is amenable to NMR solution structure determination. CopX presents some unique features, such as, a ratio between A440nm and A580nm of 0.94 and a high hyperfine coupling constant, 170 G. Taking into account the biochemical properties, CopX is proposed to be part of a new class of the type 1 copper proteins, shown preliminarily for the first time to be associated with copper resistance.
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Ekstrand, Emelie. "Mecillinam Resistance in E. coli : fitness, compensation, and resistance in different environments". Thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-330485.
Testo completoAbstract (sommario):
The global increase of antibiotic resistant bacteria threatens the modern health care and challenges the therapeutic effects of available antibiotics. The b-lactam mecillinam (Mec) is an exception to this due to a stable clinical resistance prevalence resistance of approximately 3%. It is only used to treat uncomplicated urinary tract infections (UTIs), mainly caused by E. coli. Mecillinam resistance (MecR) is easily selected for in laboratory settings and linked to >40 genes, including the mrdA gene encoding the Mec target penicillin-binding protein 2. A majority of the known MecR mutations confer a severe fitness cost. Fitness is important for bacteria to survive in the bladder and clinical isolates have been shown to have high fitness. These isolates contain loss-of-function mutations in the cysB gene, which encode a positive regulator of cysteine biosynthesis. In a previous evolution experiment, fitness cost of cysB and mrdA MecR mutations was compensated and the compensatory mutations were identified. Here the compensatory mutations were reconstructed into wildtype (WT) E. coli strain MG1655, and cysB and mrdA backgrounds to study the impact of the mutations on resistance and fitness, using MIC tests and Bioscreen C assays. Our results show that the mrdA mutants only had partial fitness compensation (significantly lower fitness than WT) for all strains and all strains also increased their MecR. The low fitness is possibly an explanation for the lack of mrdA mutants outside laboratories. Of the clinically relevant cysB mutants the majority lost their resistance when increasing growth rate, some even to levels significantly higher than WT, indicating that DcysB mutations are easier to compensate for. One strain (ydjNmx2) however, had a significantly higher growth rate while remaining clinically MecR.
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Geddes, Jennifer M. H., e University of Lethbridge Faculty of Arts and Science. "Fusarium head blight of barley : resistance evaluation and identification of resistance mechanisms". Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2006, 2006. http://hdl.handle.net/10133/399.
Testo completoAbstract (sommario):
An evaluation of nineteen barley lines using three artificial inoculation methods concluded that spray inoculation was the most reproducible method and provided the greatest discrimination of resistance. Six of the nineteen barley lines were used for proteomic studies to identify defense responses following F. graminearum infection. All lines responded by inducing an oxidative burst and pathogenesis-related proteins. Differences in response magnitude and the proteins activated could be attributed to varying levels of FHB resistance amongst the barley lines. RNA microarray profiling and iTRAQ technology were used to study the interaction between two barley lines under five different treatments testing the effect of the fungus, trichothecene, and their interaction. Resistance was differentiated by the early induction of defense-related genes and the activation of the JA and ethylene defense pathways in Chevron, compared to the induction of a less efficient defense pathway in Stander; observed intra- and inter-cultivar differential responses are discussed.xvii, 196 leaves : ill. ; 29 cm.
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Al-Daoude, Antonious. "Dissecting components of plant disease resistance specified by the RPM1 resistance gene". Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406335.
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Rose, Timothy Richard. "Rural Resistance and Fracking: The Impact of Community Expectations on Resistance Formation". Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent14932082410701.
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Lo, Pui-ying. "Molecular epidemiology and antimicrobial resistance of methicillin resistant Staphylococcus aureus blood culture isolates". Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B44192885.
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Stegner, Andrew L. "Drug resistance in D. discoideum isolation of 4-nitroquinoline 1-oxide resistant mutants /". Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4236.
Testo completoAbstract (sommario):
Thesis (M.A.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 14, 2006) Includes bibliographical references.