The purpose of this study was to determine the plasma lipid variations during periods of low calorie diet and low calorie diet plus increased physical activity. Four male graduate students, with above normal activity levels, volunteered for the 10 week study which was divided into five experimental periods. The first, or control condition involved a two week period during which the subjects received a regular diet of normal foods equivalent to approximately 3600 calories per day. During this period 'normal' activity was maintained. The second treatment condition involved a 10 day period of a low calorie diet, with continued 'normal' activity. The low calorie diet was equivalent to approximately 1800 calories daily, of natural foods, plus one multiple vitamin pill. The third experimental period was similar to the control period; a two week period during which the subjects received approximately 4000 calories, per day, of the regular diet. Again, 'normal' activity was maintained. The fourth treatment condition was identical to the second experimental period with the additional requirement of increased daily energy expenditure, per subject, of 500 calories. The final experimental period consisted of a two week period of the regular diet with 'normal' activity. Blood samples were taken, following an overnight fast, twice during each experimental period: once mid-way through the period and again at the end. Plasma triglyceride and free fatty acid concentrations were measured in duplicate in each sample. The results of orthogonal comparisons among treatment means showed a statistically significant increase in the plasma free fatty acid concentration during the low calorie diet and the low calorie diet plus exercise treatment conditions. Increased mobilization of free fatty acids from adipose tissue triglycerides in response to the insufficient dietary supply of substrates for metabolism was cited as the mechanism responsible for the rise in free fatty acid concentration. Neuman-Keuls method was used to examine the effect of the increased physical activity during the low calorie diet periods; the results showed that the increased physical activity had no significant effect on the plasma free fatty acids. Similar statistical procedures applied to the plasma triglyceride values showed a significant decrease in the plasma triglyceride concentration during the low calorie diet and the low calorie diet plus increased physical activity periods. The stress of the low calorie diet on the habitually active subjects was responsible for the decreased levels. The lipid and carbohydrate content of the normal and the low calorie diets, as well as increased peripheral uptake of triglycerides, were suggested as possible explanations for the plasma triglyceride changes. The additional daily output of 500 Calories during the second stress condition was not of sufficient magnitude to elicit a further decrease in plasma triglyceride concentration. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

No description available.

The effect of vitamin B-6 (B-6) status on plasma fatty acids (FA) levels and lipid metabolism was investigated in this metabolic study. Eight female subjects were fed for 28 days. For the first 7 days, they were fed a constant diet containing 2.10 mg of B-6. For the rest of the period (21 days), they were differentiated in terms of B-6 intake; 4 of them were fed a low (0.93 mg/day) and 4 a high (2.60 mg/day) B-6 diet. B-6 status indices, plasma FA concentration and lipid profile were determined. Plasma pyridoxal 5'-phosphate and total B-6 concentration (P<0.01), urinary 4- pyridoxic acid and total B-6 concentration (P<0.001) showed a significant difference between the two groups at the end of the study. Erythrocyte PLP failed to show any significant difference between the two groups throughout the diet study. There was no significant difference in the plasma FA or lipid profile between the two groups. Plasma total cholesterol (TC) of the low B-6 group decreased slightly (7 %), but was not statistically significant. When comparing day 7 and day 28 values, plasma triglycerides increased (9 %) for the high and decreased for the low B-6 group. LDL-C decreased (5 %) for the high B-6 group but did not change in the low B-6 group. HDL-C decreased slightly in both groups (~8 %). There was no clear evidence that a low intake of vitamin B-6 affects the fatty acid and lipid metabolism. Further studies are required to identify the relationship between vitamin B-6 and fatty acid and lipid metabolism in humans. / Graduation date: 1997

Cyclopropenoid fatty acids (CPFA), which are a group of fatty acids produced by plants of the order Malvales, are known to induce adverse physiological effects when administered to a variety of animal species. A structurally strained cyclopropene ring is present in all CPFA and is believed responsible for the toxic action of these fatty acids. Dietary consumption of CPFA by mammals, poultry and fish has resulted in toxic responses including hepatic damage, impaired reproductive capabilities and sizeable alterations in lipid metabolism. Furthermore, CPFA have been identified as mildly carcinogenic and strongly cocarcinogenic towards rainbow trout (Salmo gairdneri). The mechanism by which CPFA enhance carcinogenesis is currently not understood. The research in this thesis has therefore been directed toward obtaining a better understanding as to how CPFA induce toxic responses in rainbow trout. Hepatic plasma membranes were isolated from both control trout and trout which had consumed dietary CPFA. The plasma membranes were then compared via the use of electron microscopy, chromatographic analysis of phospholipid and fatty acid content, two dimensional polyacrylamide gel electrophoresis of proteins, and Western blot analysis of concanavalin A sensitive glycoproteins. Electron micrographs revealed that control plasma membranes appeared more homogeneous than CPFA membranes and were characterized by more membrane sheets and less vesicularization. The analysis of enzyme activities revealed that CPFA caused a decrease in whole liver glucose-6-phosphatase activity and that control plasma membranes expressed slightly higher glucose-6-phosphatase and 5'-nucleotidase activities as compared to CPFA membranes. Although dietary CPFA appeared to have no effect on the phospholipid content of the plasma membranes, significant alterations in the fatty acid profiles of ethanolamine and choline phospholipids were observed. CPFA caused a decrease in palmitic, palmitoleic and oleic acids while the level of stearic and docosahexaenoic acids subsequently increased. Differences between the protein content of control and CPFA plasma membranes were made clear through the analysis of electrophoretic and Western blotting data. Membranes isolated from fish fed CPFA contained several proteins of high molecular weight (above 66,000 daltons) and other proteins of high isoelectric point that were not present in control plasma membranes. Additionally, two families of glycoproteins which had previously been identified as microsomal in origin were detected only in CPFA plasma membranes. A discussion concerning the possible causes and biological ramifications of the observed subcellular alterations caused by CPFA insult is also presented in this thesis. / Graduation date: 1989

No description available.

The lipid composition of cotton (Gossypium hirsutum, L) fibers was determined. Fatty acid profiles revealed that linolenate and palmitate were the most abundant fatty acids present in fiber cells. Phosphatidylcholine was the predominant lipid class in fiber cells, while phosphatidylethanolamine, phosphatidylinositol and digalactosyldiacylglycerol were also prevalent. An unusually high amount of phosphatidic acid was observed in frozen cotton fibers. Phospholipase D activity assays revealed that this enzyme readily hydrolyzed radioactive phosphatidylcholine into phosphatidic acid. A profile of expressed sequence tags (ESTs) for genes involved in lipid metabolism in cotton fibers was also obtained. This EST profile along with our lipid metabolite data was used to predict lipid metabolic pathways in cotton fiber cells.

A dissertation submitted to the Faculty of medicine of the university of Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Masters of science Johannesburg 1991 / Carnitine plays a role in the transport of activated long chain fatty acyl groups from the site of activation to the site of beta-oxidation in the mitochondria. Endogenous synthesis of carnitine from the amino acids methionine and lysine, takes place mainly in the liver. From there free and acyl carnitine are released into the blood and transported to other tissues.A few studies have indicated that poor nutritional status may lead to carnitine deficiency.[Abbreviated Abstract. Open document to view full version] / GR2017

by Chi-Ming Wong. / Bibliography: leaves 183-193 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

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