No description available.

Most stroke survivors recover some degree of lost function after an ischemic event. Recovery however, is negatively affected by comorbid conditions such as diabetes. Successful recovery is dependent on the ability of adjacent surviving cortical tissue and functionally related areas to take over functions lost by the stroke. Recently our lab has shown that diabetes interferes with the remapping of sensory function to peri-infarct areas after photothrombotic stroke. Given this result, it is crucial to understand how diabetes affects the structure of neurons following stroke, particularly at the level of dendritic spines, which receive the vast majority of excitatory synaptic inputs. Type I diabetes was pharmacologically induced in transgenic mice expressing yellow fluorescent protein (YFP) in a subset of cortical neurons 4 weeks prior to receiving unilateral photothrombotic stroke in the forelimb area of the primary somatosensory cortex (FLS1). Spine density measurements were made on the apical and basilar dendrites of layer-5 pyramidal neurons at 1 and 6 weeks after stroke. Our analysis indicated that diabetes was associated with fewer apical and basilar dendritic spines in the peri-infarct region 1 week after stroke. At 6 weeks of recovery, peri-infarct dendritic spine density in both control and diabetic animals returned to baseline levels. These changes were specific to the peri-infarct cortex, as spine density in distant cortical areas such as the forelimb sensorimotor region of the contralateral hemisphere, were not affected by stroke. In order to relate changes in spine density to the recovery of forepaw function, we re-analyzed data from a previous study that employed the forepaw adhesive-tape-removal test (Sweetnam et al 2012). This analysis revealed that diabetes significantly increased the latency of tape removal from the impaired forepaw (when normalized to the unaffected paw) at 1 but not 6 weeks of recovery. Collectively, these findings indicate that diabetes exacerbates forepaw impairments and basilar spine loss initially after stroke, but does not affect the ability of the brain to replace lost spines over weeks of recovery. / Graduate / 0317

Human immunodeficiency virus (HIV) infection is a worldwide epidemic where infected individuals usually develop acquired immunodeficiency syndrome (AIDS). HIV is primarily spread by sexual transmission across mucosal tissue where dendritic cells (DC) reside. DC regulate immune responses through their unique ability to capture antigen, migrate to lymphoid tissue, and activate naive T cells. In this Thesis, we have investigated whether HIV influences the migration of DC, thereby influencing their capacity to regulate immune function and facilitate transport of HIV to T cell rich lymphoid tissue. Transmigration assays demonstrated that the predominant HIV strain during primary infection, R5 HIV-1, was chemotactic for immature DC (iDC). Addition of soluble CD4 enhanced iDC migration to R5 HIV, presumably by binding to R5 HIV and altering the conformation to enhance binding to CCR5. Our results suggested that iDC migrated specifically to R5 and not X4 HIV gp120, through interactions between the extracellular loop-2 (ECL-2) domain of CCR5 with the V3 loop region of R5 gp120. iDC prepared from HIV-infected subjects were shown to have impaired chemotaxis to inflammatory chemokines compared with iDC from healthy individuals. Furthermore, the level of inhibition appeared to be proportional to the severity of disease progression in HIV infected subjects. Interestingly, chemotaxis of iDC from long-term non-progressor individuals was similar to normal individuals, whereas migration of iDC from typical progressors was greatly impaired. These differences did not appear to be related to the level of CCR5 expression or patient viral load. The protease inhibitor Indinavir used in antiretroviral therapy, limited DC trans-endothelial migration to chemokines, reduced DC-SIGN expression and increased CD83 on iDC. The results suggested that Indinavir inhibited proteases necessary for DC migration by adversely affecting interactions between DC-SIGN, VLA-4 and VLA-5 and ligands on the endothelium and underlying fibronectin matrix. A novel method has been successfully developed for amplifying rare HIV-specific CDS cells using DC transfected with HLA antigens matching HIV-infected subjects. This has enabled us to amplify HIV-specific CDS T cells by 10- to 60-fold. This may help us to clone and characterise HIV-specific CDS T cells from highly exposed persistently seronegative (HEPS) individuals. In summary, the results in this Thesis demonstrate that R5 HIV mimics chemokines to subvert the natural trafficking of DC. Indeed, we have shown that DC from typical progressors have severely impaired migration. This may have serious consequences on DC immunoregulation, compromising the immune function of these infected individuals.

A range of highly ordered dendritic and oligomeric macromolecules, functionalised with tetrathiafulvalene (TTF) derivatives as a redox-active sub-unit were assembled. In particular, the first dendritic macromolecules incorporating TTF were constructed by the reaction of poly-acid chlorides and alcohol functionalities. Electrochemical techniques showed the novel redox-superstructures to be efficient π-electron donors that are able to undergo two reversible, multi-electron-on oxidations. The TTF-units were established to be acting independently, and the extent to which the redox groups could be oxidised was evaluated. UV studies demonstrated the redox- assemblies to be capable of forming charge-transfer complexes m solution and showed potential for the formation of conducting charge-transfer complexes. Preliminary studies showed the precursors to these compounds to be suitable for use as electrochemical detectors for dopamine. Structural variation of the core units increased the air and thermal stability of the dendritic materials, whilst retaining the characteristics of the multi-redox system. These systems formed stable aggregates of the radical cation and afforded conducting charge- transfer complexes with TCNQ. The new precursors to multi-TTF systems were then used in attempts to impart redox characteristics on [2]pseudorotaxanes and rotaxanes. Preliminary attempts were made to assemble multi-TTF systems using a TTF derivative as a core and at the periphery.

In addition to their activity against intracellular pathogens, it is now clear that CD8+ T-lymphocytes also mediate anti-tissue responses. In order to manipulate these responses in the setting of tumor immunity or autoimmunity, it is necessary that we understand the parameters that promote CD8+ activation. In the first section of this thesis, a transgenic mouse model was used to explore the effectiveness of peptide/adjuvant-based and dendritic cell (DC)-based vaccination techniques at eliciting CD8-mediated anti-pancreatic responses. It was found that, while peptide vaccines were unable to stimulate autoimmunity, the transfer of DCs promoted autoimmune diabetes in a manner that was dependent upon the toll-like receptor (TLR)-based maturation of the DCs. Furthermore, the diabetes induction was dependent upon the engagement of the immunodominant CD8+ population and a second T-cell specificity, indicating that polyclonal responses may be required for effective tissue destruction. In the second section of this thesis, I explored the requirements for CD28-signaling during the activation of naïve self-reactive CD8+ T-cells. The transfer of mature DCs was insufficient to promote diabetes in CD28-deficient animals, whereas infection with lymphocytic choriomeningitis virus could induce diabetes in the same animals. Anti-tissue responses were further explored in tumor-bearing mice following DC transfer and demonstrated that a critical determinant of the induction of anti-tissue immunity in the absence of CD28-derived costimulatory signals, was the persistence of antigen presentation. In the final section of this thesis, I explored the role of nuclear factor kappa B 1 (NF-κB1) in DC maturation using the DC transfer model described above. Surprisingly, NF-κB1-deficient DCs were capable of inducing diabetes without the need for external stimulation. Furthermore, the absence of NF-κB1 in unstimulated DCs was associated with dysregulated production of tumor necrosis factor alpha (TNF-α), and this cytokine was required for the proper upregulation of the cytotoxic effector molecule granzyme B in CD8+ T-cells that infiltrated the pancreatic islets. This work therefore presents a novel model of autoimmune tissue destruction, in which defined genes and pathways that contribute to DC-T-cell interactions can be explored in an in vivo non-TCR transgenic setting.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available online.

Thesis (Ph.D.)--Virginia Commonwealth University, 2006. / Title from title-page of electronic thesis. Prepared for: Dept. of Pharmacology & Toxicology. Bibliography: leaves [190]-207.

Thesis (Ph. D.)--Case Western Reserve University, 2008. / [School of Medicine] Department of Pathology. Includes bibliographical references.

Thesis (M.S.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.