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In this thesis, some aspects of impaired neuromuscular transmission have been investigated by electrophysiological means. Myasthenia gravis (MG) is an autoimmune muscle weakness disorder, caused by antibodies (Abs) directed against the acetylcholine receptor (AChR). However, in 10-15% of patients who show clinical symptoms of MG, there is no detectable anti-AChR antibody as shown by routine radioimmunoassays ("antibody-negative" patients). It is possible, however, that Abs may be present against sites other than the AChR in the latter patients. To investigate this, mice were injected with plasma (or the immunoglobulin G (IgG) fraction) from 7 patients, and intracellular recordings made from the mouse diaphragm muscles. Each plasma/IgG studied produced a significant reduction in miniature end-plate potential (mepp) amplitude. This did not appear to arise by a postsynaptic action since a-bungarotoxin binding and/or ACh sensitivity were unaffected. Also, analysis of voltage noise during ACh exposure showed no effect on single channel properties for those plasmas investigated. Furthermore, of the 7 plasmas studied, 4 gave significant reductions in end-plate potential (epp) quantal content. The results suggest an autoimmune basis of "antibody-negative" MG, with antibodies apparantly acting presynaptically, perhaps by interfering with vesicle packaging. Experiments were also performed to investigate the actions of anti-AChR Abs present in 85-90% of patients with MG. The effects of acute applications of the Ig fraction on biopsied human muscle were studied. Mepp amplitude was significantly reduced as compared to controls by the MG Ig. Thus acute blocking actions of anti-AChR Abs may be important in the pathogenesis of normal MG. Finally, possible modulation of neuromuscular transmission by the Ca2+ channel agonist CGP 28392 (2pM) was studied. This compound had no significant effect on epp quantal content, on mepp frequency in high potassium (K+) solutions or on mepp amplitude. Thus this agent had neither pre nor postsynaptic actions at this concentration. More specifically, since CGP 28392 is an agonist at L-type Ca2+ channels, L-type Ca2+ channels appear to play no major role in acetylcholine (ACh) release at the neuromuscular junction.

There is universal recognition that the foreign policy making talent in the United States is woefully unrepresentative of America’s vibrant minority populations, and more is required to attract minorities to pursue public service careers representing the United States abroad and accurately reflect its diversity. However, little attention is paid towards the international response to America’s diversity as it relates to when people of color represent the United States as diplomats, foreign service officers and White House foreign policy officials, as well as in less official capacities as scholars and humanitarian workers. These concerns assume new relevance against the backdrop of the United States’ outsized cultural reach and the international popularity of American films that show “true American culture” and a global introspection about race in America. This presentation will examine the English Language foreign press coverage in 6 countries of the appointment of General Colin Powell, Dr. Condoleezza Rice and Dr. Susan Rice to senior WH and cabinet-level Foreign Policy positions of Secretary of State and National Security Advisor respectively from 2000 to 2013 during the Bush and Obama Administrations. Ultimately, the presentation will analyze and demonstrate the influence of gender and race in the coverage of these individuals to demonstrate the importance of diversity to offering a full understanding of the American experience.

The ecology of the fungus, Vertlciilium lecanii, and its potential as a microbiological insect cide against the aphids, MyzuS persicae, Macrosiphoniella sanborni and Brachycaudus helichrysz, on glasshouse chrysanthemums have been examined. To achieve reproducibility, a single-spore isolate of V. lecanii, C-3, was used and designated as standard. It produced conidiospores on solid media and, more abundantly and readily, blastospores in liquid media. In nutritional studies, submerged production of conidiospores was not achieved. In aqueous suspension, conidiospores survived longer than blastospores. Conidiospores exposed below 80% relative humidity soon died, the speed of death depending on the spore microenvironment. A bioassay technique was developed and is believed to be the first statistically reliable method of quantifying fungal spore pathogenicity towards insects. With M. sanborni.the semi-weighted mean lethal concentration 50% of 28 assays was 1.83 x 10"' spore /ml suspension (fiducial limits, 1.45 and 2.31). All but one of 15 V„ lecanii strains, some pathogens of other insects and some probable hynerparasxtes of rust fungi, were similar in pathogenicity to C-3, Five other strains, all from rust or mildew fungi, were apathogenxc. B. astospores of C—3 were approximately twice as pathogenic as conidiosporeso With single- and multi-spore isolates, repeated passage through apaids or subcu, ture on agars scarcely altered pathogenicity, but subculture greatly chanced colonial morphology. In glasshouses, blastospores and conidiospores produced similar levels of aphid control. Spore sprays established excellent control of My. persicae within 2-3 weeks, maintaining control for up to 8 weeks. Also, B. helichrysi was controlled in vegetative plant tips but not on tightly closed flower buds. Control of M. sanborni was usually unsatisfactory. In laboratory bioassays, all 3 aphid species were equally susceptible to V. lecariii suggesting that behavioural and ecological factors explain differences in glasshouses. V. lecanii could be used advantageously in integrated control systems on chrysanthemums.