Adult male guinea pigs were maintained on four dietary regimens for a period of 8 weeks. The basic diet consisted of powdered guinea pig chow with 10% coconut oil. The three experimental groups received the basic diet with additions of either 1% lecithin, 0.25% cholesterol, or 0.25% cholesterol plus 1% lecithin. Blood was sampled periodically for the determination of plasma cholesterol, phospholipids, lecithin:cholesterol acy1transferase activity (LCAT), and platelet aggregation. Animals were sacrificed at eight weeks and the concentrations of cholesterol in selected tissues and in the carcass were determined. The cholesterol-fed animals gained less weight than did the controls; this was associated with reduced food consumption and also decreased feed efficiency. The plasma lipids responded to cholesterol feeding with a sharp increase in total cholesterol, free cholesterol, total phospholipids, phosphatidyl choline (PC), and lysophosphatidyl choline (LPC). The ratio of cholesterol:phospholipid increased, whereas the ratios of cholesterol ester:total cholesterol, LPC:total phospholipid, and LPC:PC declined. The reduced percentage of cholesterol ester and LPC suggested a limited ability to esterify the high levels of circulating cholesterol that accompanied cholesterol feeding. Although the net esterification (micromoles of cholesterol esterified) by LCAT increased with cholesterol treatment, the percent of plasma cholesterol esterified (fractional esterification) declined. Addition of lecithin to the cholesterol diet did not prevent the sharp rise in plasma cholesterol, phospholipids, or their fractions. The net esterification increased in plasma of animals receiving lecithin plus cholesterol. Nevertheless, the increase in LCAT activity was insufficient to maintain the proportion of esterified cholesterol at the level found in control animals. There was an increase in total phospholipid, PC, and LPC in plasma of guinea pigs supplemented with lecithin only; no change in cholesterol or cholesterol ester of plasma was seen. The molar esterification rate was positively correlated with plasma concentrations of both the substrates (free cholesterol and PC) and the products (cholesterol ester and LPC) of LCAT action. There was a strong positive correlation between the fractional esterification rate and the percent of esterified cholesterol, percent of LPC, and the ratio of LPC:PC. Cholesterol treatment produced an increase in the relative sizes of spleen and liver, and definitely increased the cholesterol deposition in the total body as well as selected tissues (spleen, liver, kidney, lungs, digestive tract). The increased deposition in the liver as well as total body was even greater when lecithin was included in the atherogenic diet. Sudan staining of thoracic aorta revealed plaques especially around the aortic arch of animals receiving cholesterol only; the addition of lecithin to the atherogenic diet resulted in a reduced number of plaques. ADP-induced platelet aggregation was enhanced with cholesterol feeding. The sensitivity of platelets to ADP aggregation was reduced in animals treated with lecithin plus cholesterol. The correspondence of platelet aggregation to the prevalence of aortic plaques suggests that contact with damaged vascular walls may have altered platelet sensitivity. Positive correlations existed between platelet aggregation and plasma concentrations of free and esterified cholesterol as wel1 as PC and LPC. The overall results suggest that the increase in the rate of cholesterol esterification and the decrease in the platelet sensitivity may be the mechanism by which lecithin reduces the incidence and severity of atherosclerosis. / Graduation date: 1978

The effect of supplementary lecithin on plasma lipids was studied. Thirty-one men between the ages of 38 and 56 were given 7.2 gm of supplemental lecithin per day in the form of Soya Lecithin. Supplementation lasted for a period of seven and a half to eight weeks. Blood was analyzed both before and after supplementation in order to determine total plasma phospholipid, triglyceride, cholesterol and total lipid levels. Supplementary information was obtained about smoking habits, activity levels and percent of desirable weight for each subject. The phospholipid profile of randomly selected samples was also determined in order to find any possible changes in the individual phospholipids. There was no significant change in either phospholipid, triglyceride, total lipids, or the individual phospholipids, However, there was a significant increase in cholesterol. A positive correlation between plasma triglycerides and both cigarette smoking and the percent of desirable weight was discovered. There was also a negative correlation between activity and plasma triglycerides. / Graduation date: 1976

The effect of oral lecithin supplementation on plasma lipids was investigated. Thirty-one healthy middle-aged men received 7.2 gm soy lecithin daily for two months. Blood was drawn both before and after supplementation and analyzed for total and esterified cholesterol, total and individual phospholipids, total lipids, triglycerides, and lecithin:cholesterol acyltransferase (LCAT) activity. Information on dietary intake, physical activity, smoking habits and relative weight was also obtained. The proportion of cholesterol ester increased significantly (p < 0.01) with supplementation, as did LCAT activity (p < 0.025). None of the other lipid parameters changed during the experimental period. A positive correlation was found between LCAT activity and the ratio of lysophosphatidyl choline to phosphatidyl choline. Triglycerides were positively correlated with smoking and percent of desirable weight, and negatively correlated with activity level. Higher proportions of cholesterol ester were associated with more vigorous physical activity and with lower relative weights. / Graduation date: 1976

Graduation date: 1980

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 316-331).

No description available.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 106-112).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

No description available.