Thesis (Ph. D.)--University of Chicago, Dept. of Chemistry, June 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 90-96). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2006. / Title from metadata title field (viewed Nov. 13, 2006). Includes bibliographical references (p. 90-96).

No description available.

No description available.

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.

The need for new anti- TB drugs is increasingly rising because of the resistance of M. tuberculosis to existing drugs. The mycobacterial cell wall serves as an impermeable protective barrier for the bacilli from toxins and chemotherapeutic agents, mainly due to the mycolic acids waxy outer layer. The mycolic acids play an important role in the architecture and physical properties of the mycobacterial cell wall. This study was based on the observed mimicry and association between the host cholesterol and the mycolic acids. This may present yet another way in which the TB bacilli survives by manipulating its host and using some of its components for its survival. The research focused on whether the cholesterol-like molecules on the mycobacterial cell surface can be targeted for effective delivery of anti-mycobacterial agents. In order to exploit the ability of M tuberculosis to accumulate cholesterol or interact with it, a cholesterol¬binding molecule was used for targeting an anti- TB drug to the mycobacterial cell wall or to the cell membrane of infected macrophages. It was observed that the drug does possess anti-mycobacterial activities even though higher concentrations of the compound were required. This supports the idea that the ability of cholesterol to interact with the mycobacterial mycolic acids can be exploited for designing of anti- TB agents. It was also demonstrated in this study that cholesterol has a negative effect on the activity of INH. Thus cholesterol, which is required for entry and survival of M tuberculosis in the host cells, has yet another protective effect on this pathogen. The possible ability of cholesterol to target the same enzyme(s) as INH is another small piece of knowledge to complete the puzzle to understanding the mode of virulence and pathogenesis of this pathogen and develop of new ways to fight the old enemy. / Dissertation (MSc(Biochemistry))--University of Pretoria, 2006. / Biochemistry / unrestricted

No description available.

Tuberculosis has returned with vengeance mainly due to the resurgence of multi drug resistant strains incurred by non-compliance to the 6-9 months chemotherapy programme. Co-infection with HIV, which disorientates the immune response, has aggravated the situation. This study was built on previous observations that indicated that the major lipid cell wall component of M. tuberculosis, i.e. mycolic acids, a wax that envelopes and protects the bacillus from the hostile host immune system, can be purified and administered to animals for protection against subsequent tuberculosis induction. It was established in this study that mycolic acids pre-treatment can significantly protect mice upon subsequent intranasal infection with M. tuberculosis and that this protection is not attributed so much to the T helper cell immunity, but rather through induction of innate immunity. In the murine AIDS model, innate immunity induced by mycolic acids pre-treatment was not enough to protect the virally immunocompromised mice against subsequent M. tuberculosis infection. Mycolic acids administration in mice did not support tuberculosis chemotherapy to enable shortening of the duration of chemotherapy. In human tuberculosis patients, antibodies to mycolic acids could be measured in a specially adapted configuration of a resonant mirror biosensor. The preliminary investigation opened up the possibility that the prevalence of anti-mycolic acids antibodies in tuberculosis patients may be measured as a surrogate marker for tuberculosis infection. An apparent cross-reactivity between mycolic acids and cholesterol in binding to tuberculosis patient antibodies may provide far reaching insight in the role of the mycolic acids in the cell wall to facilitate infection. This research contributed significantly to the understanding of the host-pathogen interaction in tuberculosis, to open up fresh approaches to improved diagnosis and chemotherapy. / Thesis (DPhil (Biochemistry))--University of Pretoria, 2006. / Biochemistry / unrestricted

Cerithidea california is examined to determine the fecundity of the parasitic trematode species in its gonad. Five species of trematodes are studied (Cloacitrema michiganensis, Euhaplorchis californiensis, Parorchis acanthus, Himasthia rhigedana, and Acanthoraryphium sp.). Their fecundity is determined by direct counts of rediae and estimation of the cercarial population. Correlations are shown for trematode numbers and snail size. Incidences of infection are given with regard to site, snail size, and trematode species. Comparison is made between infection ratios of C. californica and another marsh snail, Batillaria zonalis.