In vitro selection for multidrug resistance (MDR) and retroactive clinical studies have established an important role for both P-glycoprotein (P-gp) and the Multidrug Resistance-associated Protein (MRP) in conferring pleiotropic resistance to several structurally dissimilar hydrophobic drugs. Both P-gp and MRP are ABC transporters which when overexpressed in tumour cells are capable of enhancing drug efflux, resulting in a drug accumulation deficit. Paradoxically, acquisition of the MDR phenotype frequently results in newfound hypersensitivity to a different group of drugs. This thesis investigates the collateral sensitivity of the P-gp-bearing CHO cell line CH$ sp{ rm R}$ C5 to the calcium channel blocker, verapamil (VRP). In addition, the hypersensitivity of the MRP-bearing SCLC line H69AR to BSO, a depleter of glutathione (GSH), is herein examined. Although VRP clearly induced heightened levels of p53-independent apoptosis in CH$ sp{ rm R}$ C5 cells, blockage of calcium channels was not involved in the cytotoxicity of the drug. BSO clearly killed through depletion of GSH, apparently resulting in heightened levels of necrosis in H69AR cells. In both cases, decreased expression of the Bcl-2 gene appeared to result in hypersensitivity of MDR cells to the toxic effects of BSO and VRP.

Birdsfoot Trefoil (Lotus corniculatus L. cv. Leo), is a perennial forage legume that has difficulty in establishing stands due to slow seedling growth, weed competition and herbicide sensitivity. The development of herbicide resistant cultivars would be of economic importance. Resistant lines were isolated after sequential selection at the callus, shoot and whole plant levels to the sulfonylurea (SU) herbicides Harmony (DPX-M6316, code name for methyl 3- ( ( ((4-methoxy-6-methyl-1,3,5,triazine-2-yl)amino) carbonyl) amino) sulfonyl-2-thiophenecarboxylate), or Classic (DPX-F6025, code name for 2(( (4-chloro-6-methoxypyrimidine-yl)amino carbonyl) aminosulfonyl)benzoic acid ethyl ester. In field and growth chamber tests the Harmony regenerant lines displayed an increased tolerance as compared to control plants from tissue culture, and from seed. Results of the evaluation of callus cultures of regenerated mutant lines signify stability of the resistance. Outcrossed seeds collected from field trials, and tested in vitro for herbicide resistance, indicate that the trait is heritable and that resistance may be due to reduced sensitivity of acetolactate synthase to SU inhibition. It is concluded that herbicide resistant birdsfoot trefoil cultivars can be isolated using in vitro selection.

There are currently more than 33 million people worldwide who are infected with HIV-1 despite development of novel treatments and knowledge of prevention strategies. Within the Pumwani area of Nairobi, Kenya there is a group of commercial sex workers who are highly exposed to HIV-1. A small subset of these women have been classified as resistant to HIV-1 infection as they remain HIV un-infected despite as many as 60 unprotected sexual exposures to HIV each year. A better understanding of such a natural model of HIV resistance would be invaluable to inform the development of a protective HIV vaccine or microbicide. Globally, heterosexual transmission of HIV across mucosal surfaces is responsible for the bulk of new infections and thus it is important to examine both the macro and the micro environments of the vaginal mucosa in efforts to determine what enhances and what thwarts HIV-infection. Previous studies have shown elevated levels of RANTES, a natural ligand for the dominant HIV co-receptor CCR5, in cervicovaginal secretions of HIV-resistant women. Additionally, a novel HIV-inhibitor, Trappin-2 was previously shown to be elevated in cervicovaginal secretions of HIV-resistant women. To test the hypothesis that RANTES and Trappin-2 in cervicovaginal fluid are important mediators of HIV resistance we will: 1) measure RANTES in a much larger group of women from the Pumwani cohort, and 2) measure Trappin-2 levels in samples taken at different time points, and 3) correlate Trappin-2 levels in cervicovaginal fluid with biological confounding variables, and 4) investigate whether SDF-1 plays a role in HIV-disease progression in HIV-positive women.

Inducible chomosomal AmpC β-lactamase (AmpC) is present in many Gram-negative opportunistic human pathogens. Expressed in response to β-lactam antibiotics, AmpC is an enzyme that can deactivate an extended spectrum of β-lactam antibiotics and thereby promote bacterial survival. Inducible chromosomal ampC is associated with ampR, a gene that encodes a LysR-type transcriptional regulator that suppresses ampC expression in the absence of β-lactam exposure. Together, ampR and ampC form a divergent operon with overlapping promoters to which the AmpR protein binds and regulates the transcription of both genes. AmpR induces ampC expression by interacting with 1,6-anhydro-N-acetylmuramyl peptide, an intermediate of peptidoglycan recycling that is generated by a glycoside hydrolase encoded by nagZ. Given the role of NagZ and AmpR in the AmpC induction pathway, the structure and function of these proteins were investigated to understand the molecular basis for how they participate in AmpC production. The crystal structure of NagZ from Vibrio cholerae was determined in complex with the glycoside hydrolase inhibitor PUGNAc (O-(2-Deoxy-2-N-2-ethylbutyryl-D-glucopyranosylidene)amino-N-phenylcarbamate) to 1.8 Å resolution. Since PUGNAc also inhibits functionally related human enzymes, the structure of the enzyme was also determined in complex with the NagZ selective PUGNAc derivatives N-butyryl-PUGNAc (2.3 Å resolution) and N-valeryl-PUGNAc (2.4 Å resolution). These structural studies revealed the molecular basis for how 2-N-acyl derivatives of PUGNAc selectively inhibit the bacterial enzyme NagZ. The effector binding domain of AmpR from Citrobacter Spp. was determined to 1.83 Å resolution and lead to the identification of a putative effector molecule binding site. In vivo functional analysis of site directed mutants of AmpR containing amino acid substitutions at the base of the putative binding pocket verified its role in AmpR function. A protocol was subsequently devised to purify milligram quantities of soluble full-length AmpR. Biochemical and biophysical analysis, including non-denaturing mass spectrometry and small angle X-ray scattering, revealed that the purified full-length protein is tetrameric and specifically binds ampC promoter DNA. In summary, this research provides the basis for the development of small-molecules that could specifically block the activity of these proteins to suppress AmpC β-lactamase production during β-lactam therapy.

During the 19th century, British imperialism and Canadian colonialism aspired to subdue, subjugate and assimilate the Plains Cree (cf. Tobias 1992:148). This particular brand of colonialism employed Indian policy – a form of structural violence—rather than military force. I argue that structural violence was both legitimized and supported by cultural violence. The distortion of history is a prime example of cultural violence. That Canada followed an honorable and just policy in its dealings with Plains Indians (cf. Tobias 1983:519) is the contemporary residue of a myth created during colonial times in political circles to justify the dispossession of Aboriginal lands and resources. In the 19th Century, Cree leaders, Piapot and Big Bear, who were perceived as threats to Canadian “progress,” were routinely publicly maligned. The “official” historical literature often uncritically reflected these prevalent ethnocentric views of the day. Critical historical theorists, however, have offered a number of opposing views. This thesis focuses attention on the literature which takes a more critical and culturally informed approach to Canadian nation-building. It places a discussion of structural constraints at the centre of an exploration of the strategies Plains leaders used to resist a variety of Indian policies including reserve settlement.

This thesis is a phenomenological, qualitative study of student resistance and seeks to contribute to an understanding of the relationship between community, communication, and resistance by exploring the social contexts that provide meaning to the resistant behaviours of six graduates of an independent Christian school. In doing so, this thesis takes a transactional perspective of resistance – a perspective that recognises students as having multiple and shifting identities, and schools as being complex, social settings which contextualises student resistant behaviours. Integral to this perspective is a communicative potential of resistance that can be used as a means of signalling, generating, and building dialogue among the various groups of people who make up the school community. This study suggest that school need to go beyond seeing resistance as purely an expression of political statements or an engagement in power struggles and consider how resistance can be a potential communicative act. Specifically, resistance signals a need for reflection and dialogue on the ways in which the ideals of that community are both intended and experienced.

The literature comparing macronutrient metabolism in healthy and diabetic subjects is abundant; however, little data exists on how non-diabetic subjects with insulin resistance handle macronutrient. We did two studies to investigate the postprandial responses to macronutrient in healthy, hyperinsulinemic and type 2 diabetic (T2DM) subjects. In the first study, twenty-five healthy, non-diabetic subjects [9 with fasting serum insulin (FSI) <40pmol/L; 8 with 40 ≤ FSI < 70pmol/L; and 8 with FSI ≥ 70 pmol/L] were fed eleven test meals (50g oral glucose with 0-30g doses of canola oil or whey protein) after an overnight fast. There were no significant FSI × fat (p=0.19) or FSI × protein (p=0.08) interaction effects on glucose response, suggesting that the effects of fat or protein on glycemia were independent of FSI of the subjects. In addition, the changes in relative glucose response per gram of fat (r = -0.05, p = 0.82) or protein (r = 0.08, p = 0.70) were not related to FSI of the subjects. In the second study, Healthy (FSI < 40pmol/L), Hyperinsulinemic (FSI ≥ 40pmol/L), and T2DM were fed five foods with 50g available carbohydrate. Among the subject-groups, the Glycemic Index (GI) values were not significantly different for each food, and the mean (±SEM) GI values of all foods were not significantly different (p>0.05). However, the mean (±SEM) Insulinemic Index of the foods was higher in T2DM (100±7, n=10) than those of Healthy (78±5, n=9) and Hyperinsulinemic subjects (70±5, n=12) (p=0.05). The Insulinemic Index was inversely associated with insulin sensitivity (r=-0.66, p<0.0001), positively related to fasting- and postprandial-glucose (both r=0.68, p<0.0001) and hepatic insulin extraction (r=0.62, p=0.0002). The oral-glucose data were pooled from the two studies to investigate whether there was any relationship between GLP-1 and insulin sensitivity, β-cell function and hepatic insulin extraction. No significant correlation was observed (p>0.05). The results suggest that the glucose-lowering effect of fat and protein is not affected by insulin sensitivity. GI is independent of the metabolic status of the subjects; however, unlike GI, Insulinemic Index is influenced by the metabolic status of the subjects, and thus may have limited clinical utility.

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