Background: Antimicrobial resistance (AMR) is a widely recognized threat to global health that has been accelerated by the overuse of antimicrobials. Policy and regulatory interventions offer a useful approach to bring about widespread change in antimicrobial use. Objectives: This dissertation aims to investigate and characterize the role of policy interventions on antimicrobial use, to understand which policy levers have been used, which interventions have proven to be effective, and to identify analytic strategies that assist researchers and policymakers in developing evidence-informed approaches to address human AMR. Methods: To investigate effectiveness of policy interventions, I developed a systematic review and evidence map and appraised the quality of research on government policies to reduce antimicrobial use. To evaluate the extent of policy action on AMR in the Canadian context, I conducted an environmental scan of AMR action between 2008-2018. Finally, to facilitate advances in the scientific evidence base on antimicrobial resistance policy, I developed a framework for planning, conducting, and disseminating AMR intervention research. Findings: Governments have a variety of policy options at their disposal to respond to the growing threat of AMR, however, most of these policy options have not been rigorously evaluated and their effectiveness is unknown. Some regulatory, communication, guidelines, and fiscal interventions have been effective in particular settings, however, the interventions were too disparate to generalize about the effectiveness of any particular policy approach and reporting gaps in pose challenges for interpreting and replicating study results. In Canada, policy interventions have been too few, too small and too uncoordinated to achieve our AMR goals. Building on these findings, I developed a framework for planning, conducting, and disseminating AMR intervention research that identifies challenges, areas for increased coordination with policymakers, and best-practices for overcoming common limitations in AMR research. Discussion: Governments around the world have committed to respond to AMR, however, rigorous evidence to inform their policy and regulatory strategies is lacking. As the threat posed by AMR grows, it is increasingly important to strengthen the scientific evidence base on AMR policy interventions, to learn from existing policies and programs, and integrate scientific evidence into the global AMR response.

No description available.

The primary aim of this thesis was to synthesize a new class of peptide mimics derived from N-acylisatins and to investigate various methodologies for their synthesis. N-Acetylisatin 15 and its derivatives 39 and 40 were found to undergo facile nucleophilic ring-opening with amino acid esters yielding a range of 2-acetamidophenylglyoxylamide derivatives in moderate to good yields. This type of reaction was also found to work for di- and tripeptide methyl ester hydrochlorides leading to a range of N-glyoxylamide peptide mimics. The methodology of the reaction conditions was further extended to N,N′-oxalyl bisisatins 17 and 134, and 1,3,5-tris(2,3-dioxoindoline-1-carbonyl)benzene 168 substrates and their reaction with amino acid esters gave a new range of C,C′-linked-bis-glyoxylamide peptide mimics and C,C′,C′′-linked tris-glyoxylamide peptide mimics respectively. Meanwhile, reactions of N-acylisatins with 1,10-diaminodecane 155 and tris(2-aminoethyl)amine 167 gave the corresponding bis and tris-glyoxylamides. In the event of introducing amino acids at the N-1 position of isatin 9, a range of NH protecting groups for the synthesis of N-protected amino acid acyl isatins 193 were examined. It was found that the phthalamido group, e.g. phthaloylglycine 197, was the best protecting group for the introduction of a glycine unit at the N-1 position of isatin 9. Additionally, a viable and interesting alternative approach utilizing N-succinyl acylisatin 158 as the starting material was also demonstrated. In continuation of our interest in the peptidomimetic approach, a new class of cyclic peptide mimics using Grubbs?? ring-closing metathesis approach was also successfully synthesized. A range of bis-O-allyl substrates 237, 240, 242 and 246 were prepared from reaction of the corresponding N-acylisatins with L-valine allyl ester hydrochloride 236 and 1,10- diaminodecane 155 respectively. High conversion yields of the target macrocyclic systems 238, 241 and 243 were observed when the bis-Oallyl substrates were irradiated with Hoveyda-Grubb catalyst in a microwave reactor. These latter studies will provide a synthetically versatile platform for the future design of potential new drugs candidates against Gram-positive bacterial infections

Multidrug resistance (MDR) is one of the foremost causes of treatment failure in childhood malignancies. MDR is a multifactorial process, but classic resistance to cytotoxic drugs has most often been associated with over-expression of one or more MDR transporter proteins in malignant cells, conferring on them the ability to extrude an extraordinarily diverse array of endo- and xenobiotics out of the cell. The best characterized multidrug transporters, P-glycoprotein (Pgp) and the Multidrug Resistance-associated Protein (MRP), belong to the ATP-binding cassette (ABC) gene superfamily, and have been previously implicated in the development of drug resistance in the clinical context. The work described herein examined the various aspects of the MDR genotype and phenotype in the childhood malignancies acute lymphoblastic leukaemia (ALL) and neuroblastoma. The first series of studies tested the hypothesis that morphine, a potential Pgp substrate, might influence the efficacy and/or toxicity of clinically used chemotherapy agents which are substrates for Pgp. The results, however, provided no evidence in a variety of human tumour cell lines of morphine influencing response to selected chemotherapeutic drugs. This finding is particularly important as morphine remains to be the opioid of choice for the treatment of cancer pain in the clinic. The second series of studies examined the effect of single nucleotide polymorphisms (SNPs) in the MDR1 gene, encoding Pgp, and in the MRP1 gene, on patient outcome in childhood ALL or neuroblastoma, with a view to identifying novel prognostic markers for these malignancies. It was found that two of the examined SNPs in the MRP1 gene were associated with improved outcome in neuroblastoma, which had not previously been demonstrated in this disease. Moreover, each of the relevant MRP1 SNPs were associated with lower MRP1 gene expression in both patient samples and tumour cell lines, supporting previous studies indicating that low MRP1 expression in neuroblastoma is strongly associated with improved patient outcome. Importantly, the results of this study suggest a role for selected MRP1 polymorphisms in predicting clinical response in neuroblastoma. Finally, a series of studies were undertaken, using both in vitro and in vivo model systems, to test the efficacy of putative small molecule inhibitors of the MRP1 gene and its transcriptional regulator, the MYCN oncogene, in neuroblastoma. These studies demonstrated for the first time the efficacy of a novel compound, 4H10, at reversing multidrug resistance either in cultured neuroblastoma cells, or in the MYCN transgenic mice, which develop neuroblastoma that closely mirror the human disease. The results indicate that inhibition of MRP1 function has potential clinical importance in the treatment of neuroblastoma, and therefore warrant further research in this area. In contrast, the results failed to provide evidence of the in vivo efficacy of the novel putative small molecule MYCN inhibitors analysed in these studies. Collectively, the findings of these studies contribute to a better understanding of the mechanisms of clinical drug resistance, and may help in the development of new approaches for risk assessment and treatment of aggressive childhood malignancies and thereby improve the long-term outlook of children diagnosed with these debilitating diseases.

Multidrug resistance (MDR) is one of the foremost causes of treatment failure in childhood malignancies. MDR is a multifactorial process, but classic resistance to cytotoxic drugs has most often been associated with over-expression of one or more MDR transporter proteins in malignant cells, conferring on them the ability to extrude an extraordinarily diverse array of endo- and xenobiotics out of the cell. The best characterized multidrug transporters, P-glycoprotein (Pgp) and the Multidrug Resistance-associated Protein (MRP), belong to the ATP-binding cassette (ABC) gene superfamily, and have been previously implicated in the development of drug resistance in the clinical context. The work described herein examined the various aspects of the MDR genotype and phenotype in the childhood malignancies acute lymphoblastic leukaemia (ALL) and neuroblastoma. The first series of studies tested the hypothesis that morphine, a potential Pgp substrate, might influence the efficacy and/or toxicity of clinically used chemotherapy agents which are substrates for Pgp. The results, however, provided no evidence in a variety of human tumour cell lines of morphine influencing response to selected chemotherapeutic drugs. This finding is particularly important as morphine remains to be the opioid of choice for the treatment of cancer pain in the clinic. The second series of studies examined the effect of single nucleotide polymorphisms (SNPs) in the MDR1 gene, encoding Pgp, and in the MRP1 gene, on patient outcome in childhood ALL or neuroblastoma, with a view to identifying novel prognostic markers for these malignancies. It was found that two of the examined SNPs in the MRP1 gene were associated with improved outcome in neuroblastoma, which had not previously been demonstrated in this disease. Moreover, each of the relevant MRP1 SNPs were associated with lower MRP1 gene expression in both patient samples and tumour cell lines, supporting previous studies indicating that low MRP1 expression in neuroblastoma is strongly associated with improved patient outcome. Importantly, the results of this study suggest a role for selected MRP1 polymorphisms in predicting clinical response in neuroblastoma. Finally, a series of studies were undertaken, using both in vitro and in vivo model systems, to test the efficacy of putative small molecule inhibitors of the MRP1 gene and its transcriptional regulator, the MYCN oncogene, in neuroblastoma. These studies demonstrated for the first time the efficacy of a novel compound, 4H10, at reversing multidrug resistance either in cultured neuroblastoma cells, or in the MYCN transgenic mice, which develop neuroblastoma that closely mirror the human disease. The results indicate that inhibition of MRP1 function has potential clinical importance in the treatment of neuroblastoma, and therefore warrant further research in this area. In contrast, the results failed to provide evidence of the in vivo efficacy of the novel putative small molecule MYCN inhibitors analysed in these studies. Collectively, the findings of these studies contribute to a better understanding of the mechanisms of clinical drug resistance, and may help in the development of new approaches for risk assessment and treatment of aggressive childhood malignancies and thereby improve the long-term outlook of children diagnosed with these debilitating diseases.

Thesis (M.Ed.)--North-West University, Vaal Triangle Campus, 2004.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 178-191). Also available in electronic version.

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

Escherichia coli has served as a model organism for studies in molecular genetics and physiology since the 1960s. Yet the function of 20% of the 4288 known and predicted proteins in E. coli is still not known. Almost two-thirds of these proteins have homologs in other microorganisms, but their function(s) is not known in any organism. One such protein is YciG. YciG was chosen as the focus of this study because, intriguingly, an ortholog of YciG is found in the genome of the fungus Neurospora crassa. The gene encoding YciG is predicted to be in an operon with two other genes, yciF and yciE. Genes in the same operon often encode proteins with related functions, so the study was extended to include YciF and YciE. To determine the function of these proteins, in-frame deletion alleles were constructed and strains lacking one or more of the three proteins were tested for mutant phenotypes. Expression of the yciGFE operon is induced by several stresses and is regulated by RpoS, which controls the general stress response in E. coli. Therefore, we tested the ability of the mutant strains to survive environmental stresses. Our results revealed that YciG was important for stationary-phase resistance to thermal stress, oxidative stress and, in particular, acid stress. Both RpoS-dependent and RpoS-independent acid resistance mechanisms are found in E. coli. YciG was shown to be required for RpoS-independent acid resistance, but further experiments are needed to determine whether YciG also is required for RpoS-dependent acid resistance. YciG was not required for normal exponential growth of E. coli, as mutants lacking YciG had the same growth rate as the wild-type parent. No mutant phenotypes have been found yet for mutants lacking YciF or YciE. yciE deletion mutants showed the same growth rate and the same level of acid resistance as wild-type cells. The acid resistance of yciF mutants has not yet been tested, and strains lacking YciE and/or YciF need to be assayed for their ability to survive stresses other than acid stress.

The purpose of this study was to investigate the prevalence and mechanisms of extended-spectrum cephalosporin- (ESC) and carbapenem-resistance in Escherichia coli from the GTA. A total of 526 non-duplicate E. coli clinical isolates were collected during March 1-5, 2010 from 13 participant hospitals. Among these, 71 isolates showed reduced susceptibility (rS, intermediate, and/or resistant phenotype) to cefoxitin (FOX) and/or ESC. No carbapenem resistance was detected. Extended-spectrum ß-lactamase genes detected (n=37; 52.1%) belong to the CTX-M-family, including blaCTX-M-15 (78.4%), blaCTX-M-23 (2.7%), blaCTX-M-14 (18.9%). The only plasmid-mediated ampC gene identified among FOXrS isolates (n=49; 69%) was blaCMY-2 (n=7; 14.3%). Seventeen strains (24%) were negative for all ß-lactamase genes tested. Analysis of the chromosomal ampC promoter revealed mutations associated with AmpC hyperproduction. Other mechanisms of resistance (e.g. impermeability and/or unidentified ß-lactamases) cannot be discarded. The most prevalent clone detected was ST131. IncFIA, FIB and Frep were the most common plasmid replicon types detected.