Thesis (Ph. D.)--Miami University, Dept. of Microbiology, 2006. / Title from second page of PDF document. Includes bibliographical references (p. 123-144).

Thesis (doctoral)--Uppsala universitet, 1782. / Reproduction of original from Kress Library of Business and Economics, Harvard University. Goldsmiths'-Kress no. 12264.0-1.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: Lance Manuel and Karl H. Frank. Vita. Includes bibliographical references. Also available from UMI.

Thesis (Ph. D.)--State University of New York at Binghamton, Dept. of Geological Sciences and Environmental Studies, 2005. / Includes bibliographical references.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed October 25, 2007) Includes bibliographical references (p. 82-83).

Two clinical trials investigating the effect of modulating two dietary components, tea containing polyphenols and vitamin D aimed at improving non-haem iron absorption and iron status recovery, were carried out in a cohort of healthy and iron deficient UK women, respectively. Tea has been shown to be a potent inhibitor of non-haem iron absorption but it remains unclear whether the timing of tea consumption relative to a meal influences iron bioavailability, with limited published evidence, especially in human trials. The aim of the first study was to investigate the effect of tea consumption on non-haem iron absorption and to assess the effect of time interval of tea consumption on non-haem iron absorption relative to an iron-containing meal, in a cohort of healthy female participants using a stable iron isotope (57Fe).

Background: Elevated levels of iron impair immune defence mechanisms specifically cell mediated immunity and macrophage function, favors infection with Mycobacterium tuberculosis (M.tb), its replication, progression to clinical disease and death form tuberculosis (TB). Chelation of iron in individuals with an excessive iron burden may restore host defence mechanisms, decrease M.tb viability and replication and could find application in the prevention and treatment strategies in a setting where both iron overload and TB are prevalent. Aim: The aim of this study was to investigate the effect of iron chelation on mycobacterial replication, host viability and defence mechanisms in iron-loaded monocyte-macrophages during M.tb infection. Materials and Methods: Mycobacterial replication was monitored using the microplate AlamarBlueTM assay (MABA) for M.tb strains H37Ra and H37Rv, or detection of green fluorescent protein (GFP) expression by BCG (GFP-BCG). Mitochondrial membrane potential (MMP), phosphatidylserine (PS) exposure and plasma membrane integrity of premonocytic U937 cells differentiated by vitamin D3 served as indicators of host cell viability after treatment with 500M FeSO4.7H2O alone or in combination with 500 M desferrioxamine (DFO) or silybin, and infection with M.tb at 1:1 infection ratio. Superoxide anion radical (O2-•) and total nitrate/nitrite generation was monitored as host defence mechanisms by absorption spectroscopy and fluorimetry respectively. Results: Iron supplementation enhanced intra- and extracellular growth of M.tb and BCG. Chelation of iron with DFO prevented the enhanced replication of mycobacteria promoted by iron. Iron overload increased host cell death of H37Ra-infected monocyte-macrophages through increased PS exposure and decreased MMP and plasma membrane integrity, while increasing O2-• production and decreasing NO production. DFO restored the iron-related increase in PS exposure, plasma membrane integrity, O2-• and NO production to levels similar in H37Ra-infected, iron-normal cells, while MMP remained suppressed. In contrast, infection of iron-loaded cells with H37Rv reduced the already suppressed monocyte-macrophage MMP while not affecting cell death or NO production. DFO restored the iron-related suppression of O2-• in H37Rv-infected cells, and induced the production of NO while not affecting host cell death. Conclusion: These results confirm the replication enhancing effect of iron-loading on M.tb. Its suppressive influence on macrophage viability and defence mechanisms by increasing cell death and decreasing NO production during infection, is also highlighted. The beneficial effect of iron chelation by DFO through the inhibition of mycobacterial replication and restoration of host viability and defence mechanisms are suggested. / Prof. Liza Bornman

In Limit States Design for steel structures, single plate connections are designed to transfer beam shear to supporting member. These connections, with the connection plate shop-welded to the supporting member and field-bolted to the supported beam are becoming increasingly popular due to their economy and ease of fabrication. Single plate connections are very suitable for cases where speed of erection is a primary consideration. They are particularly superior for skewed connections. Traditional design methods which deal with connection problems generally give over-conservative solutions to this complex problem. Two series of experimental investigations of single plate connections for beam-to-girder webs were conducted. A variety of connections were tested to demonstrate their feasibility and to collect data for analytical correlation studies. The ultimate goal of these tests and studies is to devise a rational basis for the design of these connections. This work is part of a comprehensive research project and the reader is referred to other papers (References 1 and 2) for completeness. Based on experimental results and theoretical correlation studies, a modified design formula is proposed in order to predict the ultimate capacity of single plate connections. The formula tries to incorporate the influences of applied loads (shear force, torsional moment, and bending moment), resistance of the single plate connection, skew angle of the connection plate and type of holes (slotted and standard) used in the connection. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Iron deficiency is the most prevalent nutrient deficiency in the world, leading to long-term developmental and health consequences in populations at risk. Also known as prebiotics, non-digestible oligosaccharides such as fructooligosaccharide (FOS), inulin, galactooligosaccharide (GOS) and lactulose resist digestion by gastric acid and pancreatic enzymes in vivo, but are preferentially fermented by beneficial intestinal bacteria once they reach the colon. Prebiotics have been shown to increase the absorption of minerals such as iron from diets, but results from studies reported in the literature at times are contradictory, and mechanisms involved are still unclear. A better understanding of the role of FOS and other prebiotics in iron absorption may lead to new dietary modification strategies to increase intake of iron absorption enhancers in plant-based diets. The objectives of this study were therefore to determine the effects of prolonged FOS, as well as Synergy 1 (a combination of long- and short-chain FOS), inulin, GOS and lactulose supplementation on iron status of anemic rats; and to assess the enhancing effects of FOS on iron absorption and elucidate the regulatory mechanism involved using the Caco-2 cell culture model. In our animal studies, male Sprague-Dawley rats were first fed a low-iron diet for 14 days prior to prebiotics supplementation to achieve an iron-deficient status. Rats receiving the low-iron diet (12 ppm Fe) showed significantly lower non-heme iron concentrations in liver, spleen and kidney, as well as lower hemoglobin level than rats receiving a normal diet (45 ppm Fe), confirming iron-deficiency anemia. At the onset of the feeding trials, anemic rats were further divided into groups with or without supplementation of prebiotics. Prebiotics were provided to the rats by dissolving in water at 5% (w/v). Rats were kept on their respective test diets for 28 or 35 days, and all had free access to food and water during the feeding trials. The results showed significantly higher hemoglobin and non-heme iron levels in anemic rats with FOS or GOS supplementation, suggesting that both FOS and GOS could have positive effects on the iron status of anemic subjects with a low-iron intake. Rat colon contents also showed significant changes in short-chain fatty acid (SCFA) concentrations, presumably due to fermentation of prebiotics by intestinal microflora. Changes in the expression of Duodenal cytochrome b (Dcytb) and Divalent metal transporter 1 (DMT-1) in Caco-2 cells were measured by Western Blot and Real Time PCR. Our results confirmed that Caco-2 cells 14 days post confluence provided a stable research model for gene expression studies related to iron absorption. At low iron level, especially with FOS or SCFA supplementation, Dcytb and DMT-1 expression levels were increased in Caco-2 cells. While at high iron level, expression of Dcytb or DMT-1 was mostly down-regulated. Effects of SCFA were much more pronounced than FOS at different iron concentrations, suggesting that any effects of dietary FOS on improving iron status would require fermentation by the intestinal microflora. Further studies on other prebiotics (e.g., GOS and lactulose) and different combinations of SCFA are warranted.

Thirty-two children were assessed for dietary, clinical, biochemical and anthropometric status at 6 months, 1 year and 2 years of age. Development was assessed by the Bayley Scales of Infant Development (BSID) Index. Using a dietary history and record, dietary iron was estimated and compared to the National Food Consumption Survey (1985) and Recommended Dietary Allowances (RDA) 10th edition. Daily iron intake decreased from 13.2 mg at 6 months to 10.3 mg iron at 1 year of age and 7.4 mg iron at 2 years of age. Iron intake and mental development were not related at statistically significant levels at any age. A stepwise multiple regression technique was employed to investigate the extent to which mental and motor development was explained with dietary variables, blood iron parameters and anthropometric measurements. Hematocrit concentration was the only variable which was consistently useful in predicting development at 1 and 2 years of age.