The necessity to obtain accurate and reliable data pertaining to the range and/or levels of mycotoxin contamination in a variety of food and feed substrates, intended for human or animal consumption, has therefore, become important. An integral part of this study will be the provision of the most suitable analytical methods for the determination of selected Fusarium mycotoxins, in maize. The culmination will be the application of those selected methodologies to a series of Transkeian maize samples associated with human oesophageal cancer-risk.

published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Medicine / Master / Doctor of Medicine

published_or_final_version / Medicine / Master / Master of Philosophy

published_or_final_version / abstract / toc / Pharmacology / Doctoral / Doctor of Philosophy

M.Tech. / Natural occurring components in human breast milk, cow milk and soy milk have shown anticarcinogenic abilities. The human breast milk protein, -lactalbumin, was found to induce apoptosis in cancer cells, embryonic cells and rapidly growing cells, when converted from its native form to a partial denatured apoptotic-inducing form. Moreover, radiation may cause irreversible changes of protein conformation at the molecular level. Native -lactalbumin is one protein that has shown a decrease in aromatic amino acid concentration and the formation of high and low molecular weight fractions when exposed to high doses of ionizing radiation. The effect of human breast milk, cow milk, soy milk and galactose (positive control) on SNO, A549 cancer cells and normal lymphocytes were investigated. Human breast milk was irradiated with low doses of Co60 ionizing radiation (0.1Gy, 1.0Gy and 5.0Gy) in order to establish the effect of these doses on the apoptotic-inducing ability of human breast milk. The techniques used included, Trypan blue dye exclusion (cell viability), haematoxylin and eosin stain (cell morphology), modified comet assay (halo) (DNA damage) and flow cytometry (apoptosis and necrosis). Findings showed that human breast milk, irradiated human breast milk and galactose induced apoptosis in the SNO, A549 cells and lymphocytes. The cell viability, cell morphology and DNA fragmentation patterns of irradiated human breast milk were similar to that of non-irradiated human breast milk, although the flow cytometry results did not correlate. Cow and soy milk did not induce apoptosis in the SNO, A549 cells and lymphocytes. The modified comet assay (halo) detected DNA damage as apoptotic or necrotic cells. A clear distinction could not be made between the two cell populations using this assay. Flow Cytometry discriminated and quantified apoptotic cells and necrotic/late apoptotic cells using Annexin V and Propidium Iodide (PI), respectively.

No description available.

published_or_final_version / Pharmacology / Doctoral / Doctor of Philosophy

The causes of childhood cancers are not well understood. That infections are believed to play an important role in childhood cancer development is of particular interest in sub-Saharan Africa, where infectious diseases are common. The objectives of this thesis were to identify childhood cancers associated with HIV, malaria, EBV and HHV-8, and to investigate child and maternal factors associated with Burkitt lymphoma and Kaposi sarcoma. In Blantyre, Malawi, 305 children diagnosed with cancer and 212 of their mothers, were recruited. Risk factor data were collected using a brief questionnaire and blood samples tested for infections. Case-control analyses were conducted to compare 148 Burkitt lymphoma cases and 22 Kaposi sarcoma case with a control group comprising 104 children with cancers other than those known to be associated with HIV. The prevalence of HIV was 6% among children with Burkitt lymphoma and 2% in controls (OR=12.4, 95% CI 1.3 to 116.2). Tumour risk increased with increasing litres of antibodies against EBV and malaria. In comparison with those who had low titres against both EBV and malaria, the highest risk of Burkitt lymphoma was among those with high titres against both infections (OR=13.2, 95% CI 3.8 to 46.6). Reported use of mosquito nets was protective against Burkitt lymphoma. The prevalence of HIV was 81% among children with Kaposi sarcoma (OR=762.7, 95% CI 44 to 13376), and risk increased with increasing HHV-8 antibodies. Prevalence of infections was also examined among children with other cancer types and no associations were identified, although the number of cases was small. Few maternal factors were found to be associated with cancer in children. This research demonstrates that infections play a particularly important role in increasing the risk of Burkitt lymphoma and Kaposi sarcoma in children in sub- Saharan Africa. Prevention or early treatment of these infections may be vital in the control of childhood cancer.

Induction of ITF expression significantly enhanced invasion of Rat-2 (1.8-folds) without promoting proliferation. The increase in invasiveness was accompanied by an upregulation of beta-catenin (18.0%) and MMP-9 (67.8%), and downregulation of E-cadherin (29.7%) and TIMP-1 (34.7%). Silencing ITF in MKN45 markedly delayed the onset of tumor progression by Day 6 and reduced the tumor volume by 85% by Day 14. ITF siRNA significantly attenuated angiogenesis in vivo and in vitro. The effects of silencing ITF were mediated through transcriptional upregulation of the Bax (114%), Bak (89%), Ang-2 (89%) and Tie-2 (399%). Bcl-2, Bcl-xL, VEGF and Ang-1 expressions were not significantly altered. Silencing ITF in gastric cancer cells increased the effect of cisplatin-induced apoptosis in a dose-dependent manner. / Our findings suggested that ITF plays a role in invasion, proliferation and angiogenesis. The mechanisms involve regulation of catenin-cadherin complexes, balance of MMPs/TIMPs, proapoptotic Bcl-2 family members and Ang-2/Tie-2 system. Silencing ITF enhanced the chemotherapeutic response of gastric cancer cells to cisplatin. Blocking ITF expression using RNA interference may have a potential therapeutic application in gastric cancer. (Abstract shortened by UMI.) / The aim of this project was to define the role of ITF in gastric carcinogenesis. The thesis consisted of two parts of scientific studies to investigate the effects of: inducing ITF expression on the proliferation and invasion of non-tumorigenic rat fbroblast cells (Part 1); and silencing ITF on the proliferation, angiogenesis and chemotherapeutic response in gastric cancer cells (Part 2). / Chan Yik Wai. / "August 2005." / Adviser: Francis Ka Leung Chan. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3719. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 124-139). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.