Bibliography: leaves 105-151. / xi, 151, [47] leaves, [3] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis examines the effect of remodelling HDL on the metabolism of apo A-I. The major focus is on the effects of CETP and LCAT in the regulation of apo A-I concentration in DHL. The effects of incubation of HDL with CETP in the presence of VLDL and/or LDL on apo A-I concentration in HDL are examined. The characterization of the dissociated apo A-I from HDL is presented. The studies demonstrate that the dissociation of apo A-I from HDL mediated by CETP is preventable and reversible in a process dependent on LCAT activity. The mechanism by which HDL apo A-I content is increased is also explored. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1997?

Bibliography: leaves 105-151. / xi, 151, [47] leaves, [3] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis examines the effect of remodelling HDL on the metabolism of apo A-I. The major focus is on the effects of CETP and LCAT in the regulation of apo A-I concentration in DHL. The effects of incubation of HDL with CETP in the presence of VLDL and/or LDL on apo A-I concentration in HDL are examined. The characterization of the dissociated apo A-I from HDL is presented. The studies demonstrate that the dissociation of apo A-I from HDL mediated by CETP is preventable and reversible in a process dependent on LCAT activity. The mechanism by which HDL apo A-I content is increased is also explored. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1997?

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2008. / Härtill 3 uppsatser.

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

Diss. (sammanfattning) Umeå : Umeå universitet, 2006. / Härtill 3 uppsatser.

Thesis--University of Oklahoma. / Bibliography: leaves 61-68.

Thesis--University of Tampere, 1987. / Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 98-112).

This study aimed to investigate lipoprotein metabolism in male hamsters fed diets considered to be atherogenic in humans. Livers from adult male hamsters were selected to study aspects of apolipoprotein B metabolism. Isolated hepatocytes in suspension were compared with those maintained under tissue culture conditions. Liver slices were also prepared and compared with isolated suspended hepatocytes. Freshly prepared hepatocytes from the animals were incubated with radiolabelled precursors in suspension, or they were maintained under tissue culture conditions; liver slices were also investigated. The rates of total protein synthesis were of the same order in each of these systems, but protein secretion was impaired in liver slices, probably as a result of diffusion problems associated with the altered architecture of the sliced tissue. Albumin constituted 40 - 50% of the secreted proteins in each system. The rates of VLDL synthesis were increased in cells and slices prepared from animals previously fed sucrose- or fat-rich diets, but the secretion of VLDL was inhibited when diets contained unsaturated fat. The overall synthesis of apolipoprotein B was enhanced by fat-feeding; in the case of suspended hepatocytes, secretion of this protein was decreased when the preceding diet contained fats that were unsaturated; while in the case of liver slices, secretion was paradoxically enhanced. Apolipoprotein B was not degraded at significant rates in hepatocytes prepared from either control or fat-fed hamsters.

The mammalian small intestine is a major site (second in total activity only to the liver) for the synthesis and secretion of plasma apolipoproteins, and contributes significantly to overall whole-body lipid dynamics. A prominent feature of the small intestine is its exposure to periodic loads of meals often containing dramatically varying amounts or types of food components, including lipids such as tri-acylglycerols, cholesterol and cholesteryl esters. Since the trans-epithelial transport of most of these latter materials requires the elaboration of particles partially covered by apolipoproteins, the regulation of the biosynthesis or, more correctly, the availability of these proteins is an important and as yet little-understood problem. Previous studies have been conducted on systems which, for one or the other reason, have not permitted the following questions to be satisfactorily or coherently answered: Does the ingestion of fat-containing meals, either acutely or chronically, increase the rate of biosynthesis of intestinal apolipoproteins such as apo B-48, and is this the principal method of matching the "demand" with the supply of this "packaging material" needed for fat transport across the intestinal epithelial cells? Alternatively, does the maintenance of a large steady-state intracellular pool in the face of variations in intracellular apolipoprotein degradation, controlled by acute or chronic lipid ingestion, produce the required "match" between supply and demand for these proteins (as has recently been suggested in studies on liver cells)? An in vitro system was therefore devised whereby sheets of intestinal epithelial cells (enterocytes) were freshly isolated from the jejuna of adult male Syrian golden hamsters and incubated for several hours in a medium supporting steady-state protein synthesis, in a manner which was assumed to be similar to the activity just before the killing of the donor animals. (Hamsters appear on various grounds to be a better small-animal model of human lipoprotein metabolism than the more commonly studied rats). The isolated epithelial cell sheets produced primary apolipoprotein products that could be extracted from the cells or detected in the incubation media, free from the subsequent modifications that they are known to undergo in vivo. Hamsters maintained on a low-fat chow were either studied as such or subjected to a variety of dietary treatments designed to maximize (over short or long time periods) intracellular apolipoprotein requirements for the "packaging" of tri-acylglycerol-rich lipoproteins, especially chylomicrons: acute bolus administration of lipid into the gut; overnight feeding of fat-enriched food; and chronic (six week) fat feeding. Using specific antisera and immuno-precipitation techniques, apo B-48 and two other principal intestinal apolipoproteins were shown to be synthesized in the steady state by intestinal cell sheets derived from control animals and from those subjected to acute or chronic fat-containing diets. Secretion took place, however, only when prior fat exposure of the donor intestines had occurred. Pulse-chase labelling was used to compare the rates of apolipoprotein synthesis, degradation and secretion in the same cell sheet preparations. The rates of apolipoprotein B-48 synthesis did not vary significantly under conditions of low or high trans-epithelial lipid flux, supporting findings derived from in vivo experimental systems. In contrast with data from other systems, however, the biosynthesis of apolipoprotein A-IV was not reproducibly increased on fat challenge. The rates of apo B-48 degradation varied significantly and were markedly reduced under conditions of fat feeding. The experiments permit a choice between the two alternatives mentioned above: Ingestion of fatty foods, either acutely or over long periods of time, does not increase the rates of biosynthesis of apolipoproteins such as apo B-48; but variations in the rate of intracellular degradation of this and probably other apolipoproteins allows the intestinal cells to match their requirements for lipid-transporting molecules to the demands of any given situation, relying in each case on a large steady-state intracellular pool maintained by "constitutive" biosynthesis. Importantly, there seems also to be a specific, possibly related effect of fat feeding on the secretion of lipoproteins into the intestinal extracellular fluid. These conclusions coincide with those obtained by other workers from studies of apolipoprotein B dynamics in isolated hepatocytes and in the hepatoma-derived liver cell line, Hep G2. The mechanisms underlying these phenomena are as yet unresolved.