http://hdl.handle.net/1808/1952 Electronic Dissertations Search the Channel search http://kuscholarworks.ku.edu/dspace/simple-search http://hdl.handle.net/1808/6028 Title: Pseudophosphorylation of tau modulates its function and induces AD-like changes<br/><br/>Authors: Sun, Qian<br/><br/>Abstract: The microtubule associate protein tau, in a hyperphosphorylated form, loses its normal function and aggregates into insoluble paired-helical filaments (PHFs) in Alzheimer's disease (AD) and other tauopathies. The stoichiometry of phosphorylation is increased from 2-3 mol of phosphate per mole of tau in normal brain to 5-9 mol of phosphate per mole of tau in AD. In AD, the deregulation of kinases, such as glycogen synthase kinase-3beta (GSK-3beta), is believed to be associated with the generation of hyperphosphorylated tau. However, the functional contribution of hyperphosphorylation on AD is not well understood. Therefore, pseudohyperphosphorylation mutants at six or sever GSK-3beta phosphorylation sites were generated by amino acid substitution. In addition, several single, double and triple pseudophosphorylation mutants at these sites were also generated and used as controls. I studied the changes on mobility on SDS-PAGE, microtubule (MT) binding and arachidonic acid (ARA) induced polymerization. Four pseudophosphorylation mutants induced an SDS-resistant mobility change. All but three mutants had a reduced MT binding affinity and pseudohyperphosphorylation mutants did not have a greater effect compared with pseudophosphorylation mutants at single or double sites. Three pseudohyperphosphorylation mutants with retarded SDS mobility had a greater effect on ARA-induced polymerization, with reduced nucleation and elongation rate. Some pseudophosphorylation mutants had a significantly increased polymerization at high ARA concentrations compared with wild type tau. The tangle like aggregates similar to those isolated from AD brain were formed in the mixture of six pseudophosphorylation mutants. These observations suggest the increased toxicity of hyperphosphorylated tau may be induced by decreased MT binding affinity and reduced nucleation and polymerization rate. These observations also explain the potentially beneficial role of tau polymerization and NFT formation. I also studied the mechanism of ARA-induced tau polymerization. The results suggest that ARA can induce tau polymerization both as large micelles and monomers (or small micelles) and molecular nature of tau can affect the morphology of tau filament. The amount and morphology of tau filament can also be affected by surface area : inducer ratio. http://hdl.handle.net/1808/6027 Title: No Singular Truths: The Postcolonial Poetry of Arun Kolatkar, A. K. Ramanujan and David Dabydeen.<br/><br/>Authors: Nerlekar, Anjali<br/><br/>Abstract: This dissertation attempts to engage multiple elements of location, language, genre and gender in the readings of the three poets, Arun Kolatkar (1932-2004), A. K. Ramanujan (1929-1993) and David Dabydeen (1955- ). What brings them together, despite the divide of geographical location and cultural contexts, is their writing practice: through a questioning of gender roles (as figured through vernacular language and culture), they highlight the fissures in the nationalist project of India. This study explores the ramifications of this nationalist project by examining its impact within the state of India, in the Indian diaspora, and also in the construction of other nations, like Guyana. Through this examination, it will be clear that there is no symmetry between the different Indias imagined by these writers, and that each poet demonstrates the impossibility of the inclusion of all the complex identities in post-independence postcolonial nation-states. These three poets also present case studies of how postcolonial poetry engages with the Indian nation in different socio-geographical contexts. Because the West regards poetry as national and feminine simultaneously and because the new nation is structured on a cultural imprisonment of the woman, Arun Kolatkar, A. K. Ramanujan and David Dabydeen refute the modern protocols of literature, culture and nation through their work. They resist both Western and native assumptions about nation, gender, and regional culture through their bilingual poetry that interrogates these patriarchal processes. Through such a poetic unsettling of the gendered nation, they make room for various subaltern voices in their work--of Indians in Guyana and Caribbeans in England; of vernacular culture in sanskritized Brahmin South India; and of the homeless and the poor in Mumbai and in India. This dissertation examines, in individual detail, the various facets of the poets' engagement with the constructions of the poetic genre, the nation, (India in particular) and of women. It is through the undermining of the popular notions of all four categories that the poets reconfigure the role of poetry in Postcolonial studies and debunk any unitary comprehension of the Indian nation. http://hdl.handle.net/1808/6026 Title: A Combined Experimental-Computational Method to Generate Reliable Subject Specific Models of the Knee's Ligamentous Constraint<br/><br/>Authors: Clary, Chadd W.<br/><br/>Abstract: With the advancement of computational models of the knee, the opportunity exists to utilize patient-specific computational models of the knee intra-operatively to assist surgeons. A critical component for evaluation of whole knee mechanics is configuration of the soft tissue ligament structures surrounding the knee. The overarching purpose of the current research was to develop a unique methodology, utilizing both experimental and computational techniques, for efficient development of patient-specific ligament constraint model. To this end, an experimental method to manually assess knee laxity was developed, and used to evaluate changes in knee laxity after total knee replacement in eight cadaveric specimens. A computational model of ligament constraint was developed to complement the knee laxity data collected during the experimental protocol. A sensitivity study performed on the model identified the most critical ligament parameters affecting knee laxity. Subsequently, these ligament parameters were optimized using the simulated annealing algorithm to minimize the difference between the model predicted knee laxity and the experimentally observed knee laxity for four cadaveric specimens. The optimized ligament parameters were used to predict knee kinematics during an experimental assessment in a quasi-static knee loading rig. Knee kinematic predictions using the optimized ligament parameters were compared to predictions using previously published ligament parameters, and subsequently reduced the RMS difference between the predictions and the experimental kinematics by more than 50% for knee rotations. http://hdl.handle.net/1808/6025 Title: CREATING A MULTIVALENT SUBUNIT VACCINE USING TYPE III SECRETION SYSTEM TIP PROTEINS AS ANTIGENS<br/><br/>Authors: Markham, Aaron Paul<br/><br/>Abstract: Many gram-negative bacterial pathogens employ type III secretion systems (TTSS) to transport effector proteins into eukaryotic host cell membranes and cytoplasms to subvert normal cellular functions. TTSSs contain a basal body which spans the inner and outer bacterial membranes and a needle which extends the into extracellular space. With the increasing prevalence of drug resistant bacterial strains, vaccines represent one of the most promising strategies to combat these diseases. Proteins located at the extracellular needle tip of TTSSs appear to be excellent candidates for a sub-unit vaccine approach. These so called tip proteins are surface exposed and regulate the secretion of other effector proteins. This work presents pre-formulation, formulation and animal studies focused on creating a single multivalent sub-unit vaccine for five gram-negative pathogenic systems. In addition, a putative tip protein from Chlamydiae is compared to the other tip proteins using biophysical methods.