Thesis (Ph. D.)--University of Wisconsin--Madison, 1977. / Typescript. Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1980. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Cornell University. / Extract from the Physical review, n.s., v.24, no. 5.

Thesis (Ph. D.)--Cornell University, 1920. / "Reprinted from the Physical review, n.s., vol. XX, no. 2, August, 1922."

This paper outlines interview based, qualitative research that was conducted with six male youth who were previously students in my Social Studies 11 class. Within two separate, semi-structured interviews, participants were asked to discuss student resistance to anti oppressive pedagogy that focused on gender, and their understanding of masculinities. The initial purpose of this research was to find a relationship, if any, between acts of student resistance and the construction of masculinities. Participant perceptions of masculinities evolved as the dominant theme within the interviews. These discussions revealed that student understandings of masculinity were often entrenched in hegemonic language, yet contradictions were exposed between their rote definitions and personal narratives. Further, the use of media as a discourse became a venue for complicating essentialist understandings of masculinity, and for exposing multiple, fluid, versions of masculinities. Within these discussions of multiplicity, race and sexuality became two intersections of identity that took precedence. Also the intersection of teacher identity and the reading of identity terms emerged as a salient interpretation for gender discussions in the classroom. Throughout this write-up of the research are methodological considerations surrounding power, the construction of masculinity and race, and the further entrenching of heteronormativity, in the form of methodological interludes. Finally, within the conclusion, I consider the implications for practice and future directions for research in masculinities. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

Cervical cancer (CECA) and ovarian cancer (OVCA) rank first and third in the number of new cases diagnosed among gynecologic cancers，and chemoresistance severely limits their treatment success. The underlying mechanism of chemoresistance is multi-factorial and partly due to defects in drug-induced apoptosis. Cisplatinum (CDDP) -induced, p53-mediated mitochondrial cell death is controlled by Akt and is a determinant of chemosensitivity in gynecologic cancer cells. Mitochondria dynamics (fusion and fission) are involved in the regulation of mitochondria-mediated apoptosis. The tumor suppressor prohibitin 1 (Phb1) is involved in long from Opa1 (L-Opa1) processing and p53-regulated apoptosis. Whether mitochondrial fusion protein Opa1 and its protease Oma1 as well as Phb1 are involved in the regulation of chemoresistance in CECA and OVCA cells are not known. The overall objective of my research is to increase the current understanding on the regulation of mitochondrial dynamics and on its role in chemoresistance in gynecologic cancer cells. We hypothesize that CDDP induces Phb1 binding to phosphorylated p53 (p-p53) and Bak, resulting in Bak activation and mitochondrial outer membrane permeabilization (MOMP). These responses also induce Oma1-mediated Opa1 processing, mitochondrial fragmentation and apoptosis but are inhibited by high Akt level in chemoresistant cells. Here we present evidence that CDDP induces Oma1 activation, L-Opa1 processing and mitochondrial fragmentation in chemosensitive but not in chemoresistant cells. Silencing p53 expression attenuated CDDP-induced L-Opa1 loss, mitochondrial fragmentation and apoptosis in chemosensitive cells, while reconstitution of p53 in p53-deficient (mutant or null) chemoresistant cells induced Oma1 activation, L-Opa1 processing and changes in mitochondrial dynamics irrespective of the presence of CDDP. In response to CDDP, p-p53 (ser15) dissociates Phb1 from Opa1-Phb1 complex and binds to Bak in chemosensitive but not chemoresistant cells. Inhibition of Akt is required for CDDP to induce L-Opa1 processing, mitochondrial fragmentation and apoptosis in chemoresistant cells. Our study suggests a mechanism that p53 regulates L-Opa1 processing and mitochondrial fragmentation in chemosensitive cells induced by CDDP, while this pathway is suppressed in chemoresistant cells. Dysregulated mitochondrial dynamics may in part be involved in the pathophysiology of CDDP resistance. Inhibiting Akt activity and inducing Opa1 processing may serve as novel therapeutic strategies for these gynecologic cancers.

The rise of β-lactam-resistant bacteria from agricultural settings, including food-producing animals and their related food products has become a significant public health concern. Consumption of food contaminated by such bacteria may cause infection as well as the transmission of resistance genes. Here we used a mouse model to assess the impact of different antibiotic treatments on the composition of the gut microbiota and any impact on the transfer of β-lactam resistance genes between donor and recipient bacteria. Mice were inoculated with β-lactam resistant Escherichia coli and an antibiotic-susceptible Salmonella Heidelberg strain. The mice were treated with either streptomycin, ampicillin or both antibiotics. Mouse feces were collected at regular intervals and processed using selective culture techniques to capture potential transfer of resistance genes. Gene transfer was confirmed by whole genome sequencing. DNA extracted from the feces was used for monitoring changes in microbial profiles by 16S rDNA sequencing. In the absence of antibiotic treatment, the inoculated bacteria were only transiently detected and no transconjugants were recovered from the mouse feces. In comparison, antibiotic treatment changed microbial profiles in the mouse gut, enhanced colonization of the bacterial isolates, and facilitated the transfer of the resistance genes into both S. Heidelberg and commensal E. coli recipient strains. The results of this study indicated that the use of multiple antibiotics may enhance infection of opportunistic β-lactam resistant bacterial pathogens relative to single antibiotics and pose a greater risk in terms of antibiotic resistance gene transfer. Such process might occur in clinical settings where patients are under prolonged antibiotic treatments. Information gained through this study together with future work will inform the development of new policies guiding the prudent use of antibiotics.

No description available.

No description available.

Since their discovery over 40 years ago, considerable knowledge has been obtained on the diversity, and structure-function relationships of aminoglycoside acetyltransferases (AACs), responsible for antibiotic resistance among priority clinical pathogens. In recent years, investigations have expanded to biochemical characterizations of AACs found in environmental reservoirs. The successful design of next-generation aminoglycosides (AGs) depends on an up-to-date understanding of the broader AG resistome. Towards this goal, I present the first structural analysis for the unique apramycin modifying enzyme, ApmA. Apramycin is a veterinary antibiotic that is in development for clinical use. The atypical chemical scaffold provides inherent protection from many clinically relevant resistance mechanisms. Prior to the work presented herein, apmA was an uncharacterized apramycin resistance element among environmental species. I heterologously expressed and subsequently purified ApmA to characterize the nature of resistance towards this unique aminoglycoside. The results report the first acetyltransferase of the left-handed β-helix (LβH) superfamily involved in AG detoxification. Secondly, I completed a comprehensive characterization of ApmA utilizing a structurally diverse panel of AGs for susceptibility testing, protein engineering, steady-state kinetics, and x-ray crystallography. Through these approaches, I establish the structural and functional features that define ApmA’s place within the LβH superfamily and set it apart from other known AACs. The biochemical data presented describes a chemical mechanism dependent on the substrate specificity. Furthermore, I describe the molecular determinants behind AG-modification of clinically relevant AGs. Lastly, I describe the first comprehensive structural and functional study of clinical and environmental Antibiotic_NAT (A_NAT) inactivating enzymes. A pan-family antibiogram was obtained and mapped to the reconstructed phylogeny for the A_NAT family. Crystallographic analysis of representatives from each clade was completed with our collaborators from the University of Toronto. Through the analysis of several ligand-bound A_NAT complexes, I contributed to the elucidation of structural features responsible for substrate specificity. The collective findings from these chapters have extended the protein landscape involved in AG-acetylation from one commonly used fold to three distinct architectures, each unique in underlying chemical mechanism and dissemination. / Dissertation / Doctor of Philosophy (PhD) / Pathogens continue to learn new ways to protect themselves from antibiotics. With the discovery of new antibiotics becoming more challenging, global antibiotic resistance has the potential to become the next global pandemic. One solution is to redesign traditional antibiotics to escape resistance. A reliable, effective class of antibiotics currently under development are aminoglycosides. There is considerable knowledge into the sequence-structure-function relationships of proteins traditionally regarded as the sole contributors to a form of aminoglycoside resistance. My work describes the use of computational and biochemical techniques to investigate resistant elements beyond what we know is prevalent in clinical pathogens. Through these efforts I uncover structurally, and mechanistically distinct proteins capable of broad-spectrum, high-level aminoglycoside resistance produced by bacteria in various environments. These results are invaluable for the informed design of less-resistance prone aminoglycosides and antibiotic stewardship programs to limit these forms of resistance from becoming clinically prevalent.