Thesis (D.Tech.: Biotechnology)-Dept. of Biotechnology, Durban Institute of Technology, 2005 xx, 175, [14] leaves : ill. ; 30 cm / Previous studies indicate that a mutation in the non-oncogenic p53 gene is epidemiologically linked to human HCC (Ozturk, 1991; Chan et al., 2003). Hsu et al. (1991) found this link in Chinese, South African and Asian patients and Hollstein et al. (1993) found the same gene mutation in Taiwanese patients. The incidence of these aberrations is reported to be about 20- 50% in HCC’s (Kishimoto et al., 1997). There is sufficient evidence to indicate that carotenoids in addition to their well known antioxidant properties (Paiva and Russel, 1999), also affect intercellular communication, immune responses, neoplastic transformations and growth control, and cellular levels of enzymes that detoxify carcinogens (Zhang et al., 1991; Brockman et al., 1992; Pryor et al., 2000). To date studies carried out have used the rat (Foote et al., 1970; Gradelet et al., 1998) and the mule duckling model (Cheng et al., 2001) to show the protective effect of these carotenoids against AFB1 exposure. Of the well known carotenoids, lycopene and beta- carotene occur in abundance in fruits and vegetables and are safe for human consumption. Aflatoxin B1 frequently induces mutations of the p53 gene which is linked to HCC. Although there is much evidence from epidemiological studies linking the beneficial aspects of carotenoids to the prevention of cancer, the cellular and molecular mechanisms need to be understood in order to implement large scale intervention strategies to prevent AFB1 induced carcinoma. The use of chemical or dietary interventions to alter the susceptibility of humans to the actions of carcinogens and to block, retard or reverse carcinogenesis is an emerging chemoprotective strategy for disease prevention (Abdulla and Gruber, 2000; Kensler et al., 2003; Bingham and Riboli, 2004). Chemoprotection by natural products involves maintaining cellular integrity, preventing DNA alterations, activation of p53 suppressor protein and apoptosis. The aim of this study was thus to investigate the cellular and molecular mechanisms by which beta-carotene and lycopene may prevent the AFB1-induced toxic changes in human hepatocytes. In order to achieve this aim, the following objectives were set out: i. To optimise an in vitro system for the evaluation of AFB1 damage to cultured hepatocytes. ii. To determine the biochemical protection offered by beta-carotene and lycopene to AFB1-exposed hepatocytes, by measuring the mitochondrial activity, cell viability and ROS levels using appropriate enzyme assays and flow cytometry. iii. To determine the cellular protection offered by beta-carotene and lycopene to AFB1-exposed hepatocytes, by studying the morphological changes at the structural and ultrastructural levels using phase contrast light and electron microscopy respectively. iv. To determine the molecular protection offered by beta-carotene and lycopene to AFB1-exposed hepatocytes, by detecting apoptotic bodies as genomic markers and measuring the levels of p53 protein and AFB1-N7-guanine adducts produced.

Traditional liquid coolants used in metal machining are known to contain chemical carcinogens that could present serious health risks for machine operators and have inherent waste disposal concerns on the environment. In lessening these adverse effects, the manufacturing industry continually seeks to develop machining techniques incorporating liquid-less (dry) methods or environmentally benign coolants. Air-jet cooling is widely regarded as a viable alternative for liquid coolants in machining processes. This thesis proposes a novel air jet cooling arrangement, and assesses its thermal effectiveness and operational compatibility for specific requirements in metal cutting operation. For tests, steel rods were machined on a standard lathe workbench at selected cutting depth, feed and speed. Type 1040 steel, which is commonly used in automobile industry, was chosen as work piece material. Instead of traditional liquid coolant, a specially designed compressed air jet is used to dissipate heat generation in the cutting zone at the tool tip. The tool tip is presented orthogonally to the work piece to maintain conformity with relevant established cutting tool theories. A special air jet configuration based on a Ranque-Hilsch vortex tube was designed and developed for cooling the cutting zone and tool tip. The tool tip temperatures were measured by installing thermocouples at strategic locations on the tool piece and recorded on a data-logger for a range of cutting depths, feeds and speeds. The cutting power was measured with a power meter attached to the electrical power supply to the lathe. For comparison purposes, tests were also conducted with conventional single-nozzle air jets in place of the vortex-tube jets, using traditional liquid coolant and without any cooling applied to the tool tip. / A thermal vision camera was also deployed for selected tests to ascertain the temperature characteristics at the tool tip. The data was analysed to establish the thermal characteristics at the tool tip with vortex tube air jet, conventional air jet and no air jet cooling. The measured temperatures and cutting data were used to make assessments on cooling efficiency of jets used and surface finish quality of work piece. Estimates of tool life were made from the cutting theory to determine the effectiveness of the cooling systems used in the machining process. It is found that the proposed vortex tube based air jet cooling arrangement provides a highly efficient heat removal mechanism for metal cutting and delivers thermal cooling performance very much comparable to traditional liquid coolants without the inherent chemical exposure risks to machine operators and harmful impact on the environment. With the proposed air jet cooling, the tool life is very much unchanged and the surface finish quality of work piece shows no significant change while savings will realise though lesser dependency on liquid coolant requiring careful disposal and associated costs.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Thesis (Ph.D. in Biochemistry) -- University of Colorado Denver, 2007. / Typescript. Includes bibliographical references (leaves 137-161). Free to UCD affiliates. Online version available via ProQuest Digital Dissertations;

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains xi, 323 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 191-211).