Thesis (Ph. D.)--University of Missouri--Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves : 128-138). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 87-91). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 87-91). Also available on the Internet.

Thesis (M.S.)--Ball State University, 2009. / Title from PDF t.p. (viewed on June 07, 2010). Includes bibliographical references.

Submitted in partial fulfillment of the requirements for the degree of Masters in Technology in Chemistry, M.L. Sultan Technikon, 2000. / Mycotoxins are a group of natural poisons produced by certain strains of fungal species when they grow under favourable conditions on a wide variety of different substrates. These toxins have been implicated in a wide range of acute diseases in man and animals. Their toxic effects include oesophageal cancer and liver diseases in humans, and carcinogenic effects in experimental rats and poultry. Hence, there is a need to monitor toxin levels in food commodities. / M

The ability to mount an efficient immune response should be an important life-history trait as parasitism can impact upon an individual's fecundity and survival prospects, and hence its fitness. However, immune function is likely to be costly as resources must be divided between many important traits. Whilst many studies have examined host resistance to particular parasite types, fewer have considered general immune responses. Studies that have considered general immune responses tend to do so in vertebrate models. However, the complexity of the vertebrate immune system makes the examination of evolutionary aspects of immune function difficult. Using larvae of the genus Spodoptera (Lepidoptera: Noctuidae) as a model system, this study examines' genetic and phenotypic aspects of innate immunity. The aims were to assess the levels of additive genetic variation maintained in immune traits, to consider possible costs that could maintain this variation, and to assess the role of phenotypic plasticity in ameliorating those costs. A key finding of this study was that high levels of additive genetic variation were maintained in all of the measured Immune traits. Analysis of the genetic correlations between traits revealed potential trade-offs within the immune system and between immune components and body condition. In addition, it was shown that larvae living at high densities invest more in immune function than those living in solitary conditions, suggesting that larvae can minimise the costs of immune function by employing them only when the risk of pathogenesis is high.

M. Tech. / Background: Waterborne disease contributes significantly to the total global disease burden. Populations in rural areas of South Africa depend on untreated waters for consumption and sanitation. Contamination of public water supplies by harmful bacteria such as pathogenic E. coli poses a major risk for public health. Ingestion of these pathogenic microorganisms present in the contaminated and untreated waters could cause infection, leading to systemic inflammatory responses manifested by the production of various proinflammatory cytokines. To date, there is no human system test available to detect whether water, following ingestion, would cause disease (i.e. whether the water is infectious). The current water testing methods only test for the presence of indicator organisms, such as faecal coliforms, total coliforms, and Escherichia coli. A reliable in-vitro bioassay that could assess whether the water would cause an inflammatory response was investigated in this study. Objectives: Pro-inflammatory cytokines and whole-blood have been used in similar studies to detect the inflammatory responses following exposure to specific stimulants such as dust, lipopolysaccharide (LPS), E. coli and various others. It has been reported that larger numbers of these contaminants induced higher levels of pro-inflammatory cytokine expression. This implies that the pro-inflammatory cytokine expression could be used as a marker of infection since, inflammation occurs in response to infection. Successful infection is thus necessary for inflammation to occur, and high levels of pro-inflammatory cytokine expression confirm that infection has occurred. Thus if pro-inflammatory cytokines could serve as indicators for infection, these cytokines could be used as indicators for bacterial pathogenicity of water.

Diarrhoeal disease is a major cause of mortality in children in developing countries. It also remains a serious problem among all age groups throughout the world. Whereas studies to determine the epidemiological and aetiological factors of diarrhoeal disease have been reported for other parts of South Africa and the world, as yet no information is available for the Eastern Cape. Therefore this study was undertaken to determine the factors for this area. Enteropathogens were compared for the different ages in the various population groups and, where possible, seasonal and geographical differences were emphasised. A total of 7 278 faecal samples were examined by six laboratories in the Eastern Cape during the period November 1988 to October 1990. Data was recorded noting the age, sex and population group of the patients. The towns selected were Port Elizabeth, Uitenhage, Cradock, Grahamstown and their surrounding areas. The isolation rates for the pathogens studied in the various population groups were compared to those reported in similar studies in other countries. The seasonal incidences of the various selected pathogens were compared with those reported from elsewhere in South Africa. It was thought that the higher temperature of summer may influence the finding in the White population group, while rainfall would play a greater role for the Coloured and Black populations. The geographical distribution of the pathogens emphasised the difference in living conditions between the different population groups. For example a generally higher infestation rate of Helminths occurred in rural areas and in the groups living under poorer conditions. The low isolation rates for certain bacteria and the large percentage of samples from which no pathogens were isolated indicate the need for further research. However, the finding should be valuable for determining Public Health priorities and in the management of outbreaks of diarrhoeal disease.

Submitted in fulfillment of the requirements for the Degree of Master of Technology: Biological sciences at the ML Sultan Technikon, 2000. / Plant medicine is an important area of commercial activity in South Africa. This is a rapidly expanding market, thus we are evaluating natural and stressinduced compounds (phytoalexins) from plants as agents that may be able to control mycotoxins. Natural compounds from Bridelia micrantha, Warburgia salutaris, Lippia javanica and Scenecio serratuloides and stress-induced compounds (phytoalexins) from Citrus sinensis cv Valencia were screened for antitunqal and antimycotoxic activity by bioautography against a test organism (Cladosporium cladosporoides) and mycotoxin producing fungi (Fusarium moniliforme and Aspergillus flavus). / M

Bacterial aspartate transcarbamoylases (ATCase's) are divided into three classes that correspond to taxonomic relationships within the bacteria. The opportunistic pathogen Moraxeila catarrhalis has undergone several reclassifications based on traditional microbiological criteria. The previously uncharacterized ATCase from M. catarrhalis was purified to homogeneity and its chemical properties characterized. The ATCase from M. catarrhalis is a class C ATCase with an apparent molecular mass of 480-520 kDa. The M. catarrhalis ATCase is a dodecomer composed of six 35 kDa polypeptides and six 45 kDa polypeptides. The enzyme has an unusually high pH optimum of greater than pH 10. The enzyme exhibited hyperbolic kinetic with a Km for aspartate of 2 mM. A single, separate 78 kDa dihydroorotase from M. catarrhalis was identified and it was not associated with ATCase. These data support the reclassification of M. catarrhalis out of the Neisseriaceae family.