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

The Canadian Wheat Board and the Creative Re-constitution of the Canada-UK Wheat Trade: Wheat and Bread in Food Regime History

Magnan, André 31 August 2010 (has links)
This dissertation traces the historical transformation of the Canada-UK commodity chain for wheat-bread as a lens on processes of local and global change in agrofood relations. During the 1990s, the Canadian Wheat Board (Canada’s monopoly wheat seller) and Warburtons, a British bakery, pioneered an innovative identity-preserved sourcing relationship that ties contracted prairie farmers to consumers of premium bread in the UK. Emblematic of the increasing importance of quality claims, traceability, and private standards in the reorganization of agrifood supply chains, I argue that the changes of the 1990s cannot be understood outside of historical legacies giving shape to unique institutions for regulating agrofood relations on the Canadian prairies and in the UK food sector. I trace the rise, fall, and re-invention of the Canada-UK commodity chain across successive food regimes, examining the changing significance of wheat- bread, inter-state relations between Canada, the UK, and the US, and public and private forms of agrofood regulation over time. In particular, I focus on the way in which changing food regime relations transformed the CWB, understood as the nexus of institutions tying prairie farmers into global circuits of accumulation. When in the 1990s, the CWB and Warburtons responded to structural crises in their respective industries by re-inventing the Canada-UK wheat trade, the result was significant organizational and industry change. On the prairies, the CWB has shown how – contrary to expectations -- centralized marketing and quality control may help prairie farmers adapt to the demands of end-users in the emerging ‘economy of qualities’. In the UK, Warburtons has led the ‘premiumisation’ of the bread sector, traditionally defined by consumer taste for cheap bread, over the last 15 years. The significance of the shift towards quality chains in the wheat-bread sector is analyzed in light of conflicts over the proposed introduction of genetically engineered (GE) wheat to the Canadian prairies.
12

Transparency in Federal Policy-Making: the Case of Biotechnology in Animals Intended for Human Consumption

Lee, Heather January 2013 (has links)
This research project examines the degree of transparency of the Canadian Federal Government’s decision-making processes and institutions with respect to the human consumption of animals produced through modern biotechnology (biotechnology-produced animals). It provides a timely study of the Federal Government’s decision-making process; as of January 2013 the government has yet to determine whether, and how, biotechnology-produced animals are to be approved for human consumption. Foods that contain genetically modified organisms (GMOs) are already commercially widely available in Canada. Research is well underway to see if biotechnology-produced animals may also be developed and introduced into the food system. Government decisions regarding the human consumption of biotechnology-produced animals have the potential to revolutionize food systems globally and nationally. This thesis offers an analysis of primary and secondary data focusing on the degree of federal transparency with respect to regulating GMO foods generally and, more specifically, the emerging policy issues around biotechnology-produced animals. This exploration sets the stage for the following investigation of barriers as well as opportunities to fostering federal transparency with respect to policy and regulatory decisions regarding GMO foods. Findings are directed towards members of the communities of interest who are interested in questions relating to the degree of federal transparency and government approaches to foods that contain material produced through modern biotechnology.
13

A Synthetic Lethal shRNA Screen and Genetic Proof of Concept Identifies RAC1 as a Novel Target to Disrupt Plexiform Neurofibroma Formation

Mund, Julie Ann 12 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Neurofibromatosis Type 1 (NF1) is a highly penetrant autosomal dominant genetic disorder where mutations in the tumor suppressor gene NF1 leads to decreased neurofibromin. The most debilitating manifestation is the presence of complex multilineage Schwann cell-derived plexiform neurofibromas (PN). Historically, little clinical success has been achieved targeting PN through surgery or chemotherapies. I performed an shRNA library screen of patient-derived Schwann cell lines to identify novel therapeutic targets to disrupt PN formation and progression. An shRNA library screen of human kinases and Rho-GTPases was performed in NF1-/- and paired NF1 competent immortalized Schwann cell lines. Following sequencing, candidates were identified. We previously developed a novel mouse model of NF1 wherein a neural crest specific Postncre targeted loxp-flanked Nf1 that replicated the PN found in patients. Additional cohorts of mice were generated with biallelic deletion of Rac1 (Nf1f/fRac1f/f Postn-Cre+; DKO ). Mice were aged for 9 months and peripheral nerves were harvested and fixed in formalin. Peripheral nerve size was measured and tumors were identified through blinded analysis of hematoxylin and eosin and Masson’s Trichrome (collagen) stained slides. Rho family members, including RAC1, were identified as candidates through an shRNA library screen. Genetic disruption of Rac1 in the Schwann cell lineage resulted in the prevention of tumor formation in DKO mice, as observed by peripheral nerve size and histological analysis. I observed an average of 14.8 +/- 2.65 tumors per mouse in the Nf1f/f Postnviii Cre+ cohort compared to 0 tumors in the DKO (p<0.0001). Following an shRNA library screen, RAC1 was identified as a candidate to modulate PN formation. Biallelic deletion of Rac1 in vivo prevented PN formation. I demonstrate that a candidate identified in an shRNA library screen can translate to an biological effect in a mouse model of PN.
14

Overexpression of HGF/MET axis along with p53 inhibition induces de novo glioma formation in mice

Qin, Yuan, Musket, Anna, Kou, Jianqun, Preiszner, Johanna, Tschida, Barbara R., Qin, Anna, Land, Craig A., Staal, Ben, Kang, Liang, Tanner, Kirk, Jiang, Yong, Schweitzer, John B., Largaespada, David A., Xie, Qian 01 January 2020 (has links)
BACKGROUND: Aberrant MET receptor tyrosine kinase (RTK) activation leads to invasive tumor growth in different types of cancer. Overexpression of MET and its ligand hepatocyte growth factor (HGF) occurs more frequently in glioblastoma (GBM) than in low-grade gliomas. Although we have shown previously that HGF-autocrine activation predicts sensitivity to MET tyrosine kinase inhibitors (TKIs) in GBM, whether it initiates tumorigenesis remains elusive. METHODS: Using a well-established Sleeping Beauty (SB) transposon strategy, we injected human and cDNA together with a short hairpin siRNA against (SB-hHgf.Met.ShP53) into the lateral ventricle of neonatal mice to induce spontaneous glioma initiation and characterized the tumors with H&E and immunohistochemistry analysis. Glioma sphere cells also were isolated for measuring the sensitivity to specific MET TKIs. RESULTS: Mixed injection of SB-hHgf.Met.ShP53 plasmids induced de novo glioma formation with invasive tumor growth accompanied by HGF and MET overexpression. While glioma stem cells (GSCs) are considered as the tumor-initiating cells in GBM, both SB-hHgf.Met.ShP53 tumor sections and glioma spheres harvested from these tumors expressed GSC markers nestin, GFAP, and Sox 2. Moreover, specific MET TKIs significantly inhibited tumor spheres' proliferation and MET/MAPK/AKT signaling. CONCLUSIONS: Overexpression of the HGF/MET axis along with p53 attenuation may transform neural stem cells into GSCs, resulting in GBM formation in mice. These tumors are primarily driven by the MET RTK pathway activation and are sensitive to MET TKIs. The SB-hHgf.Met.ShP53 spontaneous mouse glioma model provides a useful tool for studying GBM tumor biology and MET-targeting therapeutics.
15

Food Democracy and The Construction of Risk in The Canadian and U.K. Media

Chénier, Lynn A. 11 December 2009 (has links)
Using a critical discourse analysis (CDA), this thesis examines how risks and food security, in relation to Genetically Modified (GM) foods, are constructed within the media context. The project analyzes news articles that appeared in two Canadian newspapers, The Globe and Mail and The Toronto Star, and two British newspapers, The London Times and the Guardian, during three particular time periods between 1997 and 2005. I evaluate whether or not the selected articles contribute to the public’s understanding of science, and how journalism constructs risk and uncertainty. I also evaluate the use of expert knowledge by journalists. Using the theory of Risk Society, as proposed by sociologist Ulrich Beck, the project explores the connections between political, social, and economic issues connected to globalization. This thesis concludes that journalism in both Canada and Britain does not appear to adequately inform their citizens on matters of food security and the risks of GMOs.
16

FRACTIONATION AND CHARACTERIZATION OF LIGNIN STREAMS FROM GENETICALLY ENGINEERED SWITCHGRASS

Liu, Enshi 01 January 2017 (has links)
Development of biomass feedstocks with desirable traits for cost-effective conversion is one of the main focus areas in biofuels research. As suggested by techno-economic analyses, the success of a lignocellulose-based biorefinery largely relies on the utilization of lignin to generate value-added products, i.e. fuels and chemicals. The fate of lignin and its structural/compositional changes during pretreatment have received increasing attention; however, the effect of genetic modification on the fractionation, depolymerization and catalytic upgrading of lignin from genetically engineered plants is not well understood. This study aims to fractionate and characterize the lignin streams from a wild-type and two genetically engineered switchgrass (Panicum virgatum) species (low lignin content with high S/G ratio and high lignin content) using three different pretreatment methods, i.e. dilute sulfuric acid, ammonia hydroxide, and aqueous ionic liquid (cholinium lysinate). The structural and compositional features and impact of lignin modification on lignin-carbohydrate complex characteristics and the deconstruction of cell-wall compounds were investigated. Moreover, a potential way to upgrade low molecular weight lignin to lipids by Rhodococcus opacus was evaluated. Results from this study provide a better understanding of how lignin engineering of switchgrass influences lignin fractionation and upgrading during conversion processes based on different pretreatment technologies.
17

Effects of GM Disclosure Statements on Consumer Perceptions of Selected Food Products in Survey and Sensory Panel Settings

Newcomb, Ellyn Margaret 01 April 2017 (has links)
The National Bioengineered Food Disclosure Standard (PL 114-216) will require nearly all foods sold in the U.S. to bear a statement disclosing whether they contain genetically modified (GM) material. Past studies suggest the presence of such a statement could have profound effects on consumers; however, research comparing consumer response towards different GM-disclosure statements is scarce. PL 114-216 states that GM foods shall not be considered more or less safe than their non-bioengineered counterparts, nevertheless it would benefit regulators and food manufacturers to be aware of the possible effects such disclosures might have on consumers. In a nationwide survey, multiple disclosure statements with varying degrees of public familiarity were compared to evaluate consumer perceptions and attitudes associated with each statement. Average consumer knowledge level of GM processes was also measured. The statements were then paired with actual food items to determine whether specific product categories influenced consumer responses. A select few of these statements and foods were included in a taste panel, allowing researchers to analyze if disclosure statements affected a consumer's sensorial experience. Results suggested that consumers were most favorable towards statements indicating the absence of GM-material, however they also responded less negatively towards new disclosure statements that do not have negative connotations. Additionally, consumers may react differently depending on the food accompanying a particular disclosure, although the taste panel data found no evidence that statements affected actual eating experience. Importantly, data from both surveys and taste panel suggested a disclosure statement may affect consumer willingness to buy a product.
18

The Multiple Faces of Genetically-Modified T Cells : Potential Applications in Therapy

Hillerdal, Victoria January 2014 (has links)
In this PhD thesis the potential of T-cells as therapy for disease are explored. The applications of genetically modified T-cells for treatment of cancer and autoimmune disease; the functionality and optimal activation of T-cells are discussed. Successful treatment of cancer with T-cell receptor (TCR)-modified T-cells was first reported in 2006, and is based on recognition of a specific peptide by the TCR in the context of the MHC molecule. As antigen presentation in tumors is often defective and to avoid MHC-restriction, chimeric antigen receptors (CAR) molecules containing an antibody part for recognition of cell surface antigens and TCR and co-receptor signaling domains have been developed. Activated T-cells mount an efficient immune response resulting in the killing of the cancer cell and initiating T-cell proliferation. The rationale for using genetically modified T-cells instead of isolating tumor infiltrating lymphocytes from the tumor and expanding them (TIL therapy) is that it is often very difficult to obtain viable lymphocytes that are able to expand enough in order to use them for therapy. This thesis explores the possibility of using prostate-specific antigens to target T-cells towards prostate cancer. The prostate has many unique tissue antigens but most patients with metastatic prostate cancer have undergone prostatectomy and consequently have “prostate antigen” expression only in cancer cells. We targeted the prostate antigens TARP and PSCA with a HLA-A2 restricted TCR and a CAR respectively. In both cases the tumor-specific T-cells were able to generate potent proliferative and cytotoxic responses in vitro. The PSCA CAR-modified T-cells delayed subcutaneous tumor growth in vivo. It is evident from our in vivo experiments that the PSCA CAR T-cells were unable to completely cure the mice. Therefore, we aimed to improve the quality of the transferred T-cells and their resistance to the immunosuppressive tumor microenvironment. Stimulation with allogeneic lymphocyte-licensed DCs improved the resistance to oxidative stress and antitumor activity of the T-cells. We further investigated the potential of genetically modified regulatory T-cells (Tregs) to suppress effector cells in an antigen-specific manner. Using a strong TCR we hypothesize that the phenotype of the TCR-transduced Tregs may be affected by antigen activation of those cells. We found that the engineered Tregs produced cytokines consistent with Th1, Th2 and Treg phenotypes.
19

Food Democracy and The Construction of Risk in The Canadian and U.K. Media

Chénier, Lynn A. 11 December 2009 (has links)
Using a critical discourse analysis (CDA), this thesis examines how risks and food security, in relation to Genetically Modified (GM) foods, are constructed within the media context. The project analyzes news articles that appeared in two Canadian newspapers, The Globe and Mail and The Toronto Star, and two British newspapers, The London Times and the Guardian, during three particular time periods between 1997 and 2005. I evaluate whether or not the selected articles contribute to the public’s understanding of science, and how journalism constructs risk and uncertainty. I also evaluate the use of expert knowledge by journalists. Using the theory of Risk Society, as proposed by sociologist Ulrich Beck, the project explores the connections between political, social, and economic issues connected to globalization. This thesis concludes that journalism in both Canada and Britain does not appear to adequately inform their citizens on matters of food security and the risks of GMOs.
20

Use of genetically engineered mouse models in preclinical drug development

Creedon, Helen January 2015 (has links)
The paucity of well validated preclinical models is frequently cited as a contributing factor to the high attrition rates seen in clinical oncological trials. There remains a critical need to develop models which are accurately able to recapitulate the features of human disease. The aims of this study were to use genetically engineered mouse models (GEMMs) to explore the efficacy of novel treatment strategies in HER2 positive breast cancer and to further develop the model to facilitate the study of mechanisms underpinning drug resistance. Using the BLG--HER2KI-PTEN+/- model, we demonstrated that Src plays an important role in the early stages of tumour development. Chemopreventative treatment with dasatinib delayed tumour inititation (p= 0.046, Wilcoxon signed rank test) and prolonged overall survival (OS) (p=0.06, Wilcoxon signed rank test). Dasatinib treatment also induced squamous metaplasia in 66% of drug treated tumours. We used 2 cell lines derived from this model to further explore dasatinib’s mechanism of action and demonstrated reduced proliferation, migration and invasion following in vitro treatment. Due to the prolonged tumour latency and the low metastatic rate seen in this model, further studies were undertaken with the MMTV-NIC model. This model also allowed us to study the impact of PTEN loss on therapeutic response. We validated this model by treating a cohort of MMTV-NIC PTEN+/- mice with paclitaxel and demonstrated prolonged OS (p=0.035, Gehan Breslow Wilcoxon test). AZD8931 is an equipotent signalling inhibitor of HER2, HER3 and EGFR. We observed heterogeneity in tumour response but overall AZD8931 treatment prolonged OS in both MMTV-NIC PTEN FL/+ and MMTV-NIC PTEN+/- models. PTEN loss was associated with reduced sensitivity to AZD8931 and failure to suppress Src activity, suggesting these may be suitable predictive biomarkers of AZD8931 response. To facilitate further studies exploring resistance, we transplanted MMTV-NIC PTEN+/- fragments into syngeneic mice and generated 3 tumours with acquired resistance to AZD8931. These tumours displayed differing resistance strategies; 1 tumour continued to express HER2 whilst the remaining 2 underwent EMT and lost HER2 expression reflecting to a very limited degree some of the heterogeneity of resistance strategies seen in human disease. To further explore resistance to HER2 targeting tyrosine kinase inhibitors, we generated a panel of human cell lines with acquired resistance to AZD8931 and lapatinib. Western blotting demonstrated loss of HER2, HER3 and PTEN in all resistant lines. Acquisition of resistance was associated with a marked change in phenotype and western blotting confirmed all lines had undergone EMT. We used a combination of RPPA and mass spectrometry to further characterise the AZD8931 resistant lines and identified multiple potential novel proteins involved in the resistant phenotype, including several implicated in EMT. In conclusion, when coupled with appropriate in vitro techniques, the MMTV-NIC model is a valuable tool for selection of emerging drugs to carry forward into clinical trials of HER2 positive breast cancer.

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