Thesis (M.S.)--Brigham Young University. College of Nursing, 2004. / Includes bibliographical references (p. 14-18).

Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 147-165).

Thesis--Catholic University of America, 1936. / Vita. "Literature cited": p. 42-43.

Thesis (Ph.D.) - University of St Andrews, April 2008. / Restricted until 11th April 2010.

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Delaware, 2007. / Principal faculty advisor: Colin Thorpe, Dept. of Chemistry & Biochemistry. Includes bibliographical references.

Six auxotrophic mutants of A. nidulans were crossed in a dialell cross system to obtain heterokaryous and heterozygous diploids. In order to ascertain their lipid accumulation ability, some of these mutants and diploids were tested in a minimal medium (with 3% glucose + 0.6% NaNO3), either in a shaker or in an incubator without agitation. Both, the mutants and diploids, exhibited only 4.6% lipid, on a dry weight basis. With the aim of optimising culture conditions for lipid accumulation, a wild type was cultivated in a range of different media and cultural conditions. The best yield (about 24%), was achieved in a modified minimal medium (MM + 12% glucose + 0.1% NaNO3), with a vortex stirrer device. The lipid composition of wild type 16 grown in a fermenter was determined. The results obtained from cells grown in two different media and using two extraction methods were compared. Fractionation of the total lipid on a Florisil column showed that this strain is composed of 86% neutral lipid, 7% glycolipid and 7% phospholipid, after isopropanol (IP) extraction, whilst chloroform-methanol (CM) extraction gave 75% neutral lipid, 8% glycolipid and 17% phospholipid. A further fractionation on hydrated Florisil showed that CM extracted sterols (both free and esterified) more efficiently than IP. Therefore, CM was considered a better extraction method, particularly for protein-bound lipids. The separation of the neutral lipid fraction into sub-classes also showed that the enhanced lipid content achieved in modified minimal medium, compared with a previously reported medium, was accounted for mainly by an increase, not in the triglycerides as was expected, but in the amount of sterols. TLC analysis of glycolipid and phospholipid from IP and CM extraction demonstrated two major glycolipid components (monoglycosyl and diglycosyl diglycerides) and that phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were the principal phospholipids with lesser amounts of phosphatidylinositol, phosphatidylserine, phosphatidylglycerol, cardiolipin and phospbatidic acid (PA) after CM extraction, whilst after IP extraction only PC, PE and PA were found. Another significant difference between the two extraction methods is the large amount of PA found after CM extraction, but not after IP, showing that, almost certainly, phospholipase D activity had occurred during the process of extraction and/or storage of the lipid. It was also found that the principal phospholipid attacked by the enzyme was PC. The fatty acid composition was determined by GLC. The major fatty acids found in the total lipid were: 16:0 =21%; 17:0 =5%; 18:0 =18%; 18:1 = 20%; 18:2 = 35%. Each lipid class showed a different and distinctive fatty acid composition, exhibiting variation with the growth medium and extraction method used. Of particular interest was the sterol ester fraction which contained margarinic acid (17:0) as its only fatty acid.

This thesis investigates the fatty acid production from carbohydrates using C. butyricum. In nature a common route for the anaerobic degradation of carbohydrate in the environment is via methanogenesis. At the heart of these processes however, is the metabolism of a diversity of carbohydrate materials that produce a few fatty acids (acetate and butyrate) which are then slowly converted to methane. In this context, fatty acids can be considered as a common end- product/intermediate from carbohydrate degradation that could be used to produce chemicals. Already, acetic and butyric acid are important feedstock chemicals in the pharmaceutical, food and industrial sectors and there is potential to expand this further. As a first step to investigate the conversion of waste carbohydrate to fatty acids for chemical production, C. butyricum, a strictly anaerobic bacterium, was investigated as a model system for the potential production of acetic and butyric acid. The production efficiency of C. butyricum relies on the type of substrate, production methodology, the strain and environmental conditions. Pure cultures of C. butyricum were investigated for fatty acid production from carbohydrates. Initial studies involved medium optimization in test tube culture for high growth rate and maximum biomass production (ODmax)- In this medium, glucose was selected as the main substrate together with yeast extract, KH2PO4 and NH4(SO)4. The studies were carried out in three types of pH controlled reactors; batch stirred tank (SRT), continuously stirred tank (CSTR) and membrane bioreactor (MBR) A comparison the fatty acid production kinetics and productivity in each reactor was undertaken and the effect of glucose concentration and where appropriate, glucose feed rates, were also investigated. The results show that fatty acid production could be carried out in all three fermentation systems. A common observation in these systems was that fatty acid production was influenced by the glucose concentration in that at low glucose concentration the ratio of acetate to butyrate was about 30:1 while at higher concentrations the ratio was reduced to about 3:1 on a molar basis. The detailed kinetic studies generated unique data for this organism and shows that the maintenance coefficient (ms) increase with increasing glucose concentration (0.02 to 1.1 g substrate/g cell/h), due to mainly to end product inhibition and the true yield (Yx/s was around 0.2 for all glucose concentrations tested. Meanwhile substrate saturation (KJ decreased with increasing glucose concentrations (2.06-6.41 g/L). This observation was atypical to that observed in other anaerobic fermentations by previous workers. A comparison of fatty acid productivities using a l0g/1 glucose feed in the 3 reactors for acetic acid were 0.95 g/l/h for STR. 4.41 g/l/h for CSTR and 37.88 g/l/h for MBR and for butyric acid 0.15 g/l/h for STR, 1.27 g/l/h for CSTR and 14.34 g/l/h MBR. Although, previous work in this area is limited the data obtained in this study was also compared with other published work and this suggests that the production of fatty acid, especially acetic and butyric acid in the MBR system is by far the most productive yet reported. The results are discussed in the context of the waste treatment process for fatty acid production and its application to waste conversion and its further development.

Insulin resistance is associated with a number of metabolic abnormalities that increase the risk of developing coronary heart disease. Dietary fat has been linked with insulin resistance, with alterations in the quality as opposed to the quantity of dietary fat now thought be more important in instigating improvements in insulin resistance. The aim of this work was to investigate the effect of alterations in the dietary fat intakes of middle-aged men (n = 32) on the insulin sensitivity of glucose disposal and postprandial lipid metabolism and to explore the mechanistic links between these insulin responsive pathways. Three separate dietary interventions were conducted; the first involved an increase in the intake of n-3 polyunsaturated fat, the second a decrease in saturated fat and an increase in carbohydrate and the third a decrease in saturated fat and an increase in monounsaturated fat intake. Compliance was monitored by the measurement of red blood cell phospholipid fatty acid composition, postprandial lipid metabolism was measured over 9 hours following a high-fat breakfast (80 g fat), and insulin resistance was measured using the short insulin tolerance test. The results of the study showed that while insulin sensitivity was inversely correlated with red blood cell saturated fatty acid concentration at baseline, the insulin sensitivity of glucose disposal was unaffected by any of the dietary interventions conducted. In measurements of postprandial lipaemia, improvements were observed following the low-saturated fat / high-monounsaturated fat diet and the n-3 polyunsaturated enriched diet, however the low-saturated fat/ high-carbohydrate diet was associated with a worsening of postprandial lipaemia through an increase in the concentrations of triglyceride-rich-lipoproteins. Changes in fasting biochemical measurements were most evident in the low-saturated / high-monounsaturated diet, with an 11 % reduction in total cholesterol and a 15.4 % reduction in fasting triglycerides. There were no observed changes in the activity levels or the gene expression of lipoprotein lipase. There was an unexpected positive association between the degree of insulin sensitivity and the extent of postprandial lipaemia, indicating that the link between these pathways is complex and warrants further investigation. Overall this work supports the view that dietary guidelines should be directed towards a change in the composition of fat, to a lower saturated fat intake, a higher monounsaturated fat intake and a lower n-6 : n-3 ratio through an increase in the intake of long chain n-3 polyunsaturated fatty acids.