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Influence of diet fat saturation on rates of cholesterol synthesis and esterification in healthy young menMazier, Marie Jeanne Patricia 05 1900 (has links)
To examine the effect of diet fat type on rates of cholesterol
synthesis and esterification during feeding and fasting, nine healthy
male subjects were fed solid-food diets of 40% fat as predominantly
either olive oil (MONO), safflower-oil margarine (POLY), or butter
(SAT). At the end of each two-week diet trial, subjects were given
deuterium (D) oxide orally and de novo synthesis was measured from D
incorporation into cholesterol and interpreted as rates of fractional
synthesis (FSR) (pools/day) into the rapidly exchangeable free
cholesterol (FC) pool. Absolute synthesis rates (ASR) were calculated
as the product of FSR and the FC pool. Pool size for each subject was
obtained from analysis of the specific activity decay curve of an
intravenous injection of 4-14C-cholesterol over nine months. Synthesis
was measured over two consecutive 12-h fed periods followed by two
consecutive 12-h fasted periods. Serum samples were also assayed for
lathosterol concentration, an index of cholesterol synthesis. Serum
cholesterol and non-HDL cholesterol concentrations were highest on the
SAT diet, lowest (P<0.001) on the POLY diet and intermediate on the MONO
diet, triglyceride levels were greater (P<0.03) on the SAT diet than on
the POLY diet, and HDL levels were lowest (P<0.05) on the SAT diet and
highest on the MONO diet. Cholesterol D enrichment and FSR during each
12-h period were greater (P<0.014) on the POLY diet than on the SAT
diet; MONO enrichment and FSR were not significantly different from
those on the other two diets. Similar results were obtained for rates of
cholesterol esterification (P<0.001). Deuterium enrichment data
suggested, and lathosterol data confirmed, that free cholesterol
synthesis was greater during the fed period than during the fasted
period (P<0.01); however, this could not be confirmed for rates of
cholesterol esterification. Results suggest that POLY fat feeding
augments de novo cholesterol synthesis without adverse effects on total
serum cholesterol concentrations, and that the deleterious effects of
SAT fat on serum cholesterol are not brought about by augmented de novo
synthesis. Finally, the combination of deuterium incorporation and
mathematical modelling produces estimates of daily cholesterol synthesis
which are compatible with those invoked by more laborious techniques. / Land and Food Systems, Faculty of / Graduate
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Studies of the Mechanism of Plasma Cholesterol Esterification in Aged RatsLee, Sun Min 12 1900 (has links)
The study was performed to determine factors influencing the esteriflcation of plasma cholesterol in young and aged rats. The distribution of LCAT activity was determined following gel nitration chromatography and ultracentrifugation of whole plasma respectively. When rat plasma was fractionated on a Bio-Gel A-5 Mcolumn, LCAT activity was found to be associated with the HDL fraction. A similar result was observed upon 24 hr density gradient ultracentrifugation of the plasma. However, following prolonged 40 hr preparative ultracentrifugation, the majority of the LCAT activity was displaced into the lipoprotein-free infranatant fraction (d> 1.225 g/ml). The dissociation of LCAT from the HDL fraction occured to a smaller extent in aged rat plasma than in young rat plasma. Plasma incubation (37°C) experiments followed by the isolation of lipoproteins and the subsequent analysis of their cholesterol content revealed that in vitro net esteriflcation of free cholesterol (FC) by LCAT as well as the fractional ufilization of HDL-FC as substrate were lower in the plasma of the aged animal as compared to that of the young animal despite the fact that the total pool of FC was higher in the former. The net transfer of FC from lower density lipoproteins (d<1.07 g/ml) to HDL provided the FC (in addition to HDL-FC) for esteriflcation in the plasma of both young and aged rats, and this process was not substantially affected by aging. Substrate specificity studies indicated that HDL from young rats was a better substrate for LCAT than the HDL from aged rats. The HDL isolated from the plasma of aged rats was enriched with apo E and had a considerably higher molecular weight than the HDL from young rat plasma. The ratio of phosphatidyl choline/sphingomyelin was lower in the HDL of aged rats. These data suggest that the decreased plasma cholesterol esteriflcation in aged rats is due to changes in the composition and size of the lipoprotein substrate (HDL).
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Development of an enzymatic method for the determination of cholesterol in food systemsSteiner, Peggy Hartz January 1978 (has links)
No description available.
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Reverse cholesterol transport in type 2 diabetes mellitusZhou, Huali., 周華麗. January 2008 (has links)
published_or_final_version / Medicine / Doctoral / Doctor of Philosophy
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The metabolic fate of lipoprotein cholesterol in isolated rat liver parenchymal cellsElzoheiry, Azza A. 27 June 1984 (has links)
The metabolic fate of cholesterol delivered to rat hepatocytes by rat plasma lipoproteins was determined. Binding and degradation of rat low and high density lipoproteins (LDL and HDL) in rat hepatocytes were studied. ¹²⁵I-labelled LDL and HDL were incubated with cells in the presence of varying concentrations of unlabelled lipoproteins for two hours at 37°C. The amount of ¹²⁵I-LDL and ¹²⁵I-HDL binding and degradation decreased by increasing concentrations of respective unlabelled lipoproteins. The presence of 50-fold excess of unlabelled LDL or HDL resulted in a reduction of ¹²⁵I-LDL and ¹²⁵I-HDL bindings by 66-82%, and degradations by 63-88%, respectively. Equilibrium dissociation constants (K [subscript d]) determined by Scatchard analysis for HDL (.15 x 10⁻⁸M) and LDL (1.04 x 10⁻⁸M) revealed that HDL have approximately 7-fold higher binding affinity for receptors on cell surface than LDL.
Specific use of LDL and HDL-cholesterol for bile acid synthesis by rat hepatocytes was investigated. When LDL and HDL labelled with ³H-LDL cholesterol was transformed to bile acids mostly as lithocholic, chenodeoxy and deoxycholic acids.
A technique developed for isolation of hepatocytes from rat liver was described. Once isolated by the technique most cells retained their microscopic structural integrity, and excluded trypan blue. The viability was 93%, which decreased to 86% after four hours of incubation.
The presented data demonstrated that both HDL and LDL bind to specific receptors on hepatocytes and undergo proteolytic degradation in rats. The study also showed that the binding affinity of HDL to hepatic receptors was much greater than that of LDL but in total binding LDL uptake was four times greater than HDL, suggesting the presence of two specific binding sites for HDL and LDL.
The first direct evidence for the preferential utilization of HDL-cholesterol for biosynthesis of bile acids in vivo is presented. This finding is compatible with the current concept of HDL as the protective lipoprotein against developing coronary heart disease. / Graduation date: 1985
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The effect of egg consumption on cholesterol distribution among lipoproteins and the ratio of Apo A-I/A-II in hyper and hyporespondersWard, Amy Sarver 16 November 1983 (has links)
The effect of increased egg consumption on plasma
cholesterol levels and its distribution among lipoproteins and
Apolipoprotein A-I/A-II ratios of high density lipoprotein
subfractions in individuals who did and did not demonstrate response
in plasma cholesterol levels was studied in 20 healthy middle-aged
men (30-55 years of age) for three months. Lunch containing 3 eggs
was fed all subjects during the first month classification period.
Subsequently, subjects were divided into hyper and hyporesponders
according to their blood cholesterol level. Thereafter, 6 eggs were
fed to hypo (n=12) while hyper (n=8) continued to consume 3 eggs
with lunch. The average plasma cholesterol level of the 20 subjects
was increased from 185±34 to 195±34 mg/lOOml during the
classification period. The mean plasma cholesterol level of the
hyperresponders was significantly (p<0.025) increased from 170±42 to
199±40 mg/100ml during classification while that of the
hyporesponders fell slightly. The additional 6 eggs consumed by the
hyporesponders for 6 weeks did not increase the mean plasma cholesterol level. The apoprotein ratios did not change as a result
of the increased cholesterol diet and were not significantly
different between the two response groups. The hyper and
hyporesponders differed significantly in initial plasma cholesterol
parameters that diminished as the subjects were challenged with
increased cholesterol consumption. These initial differences
included a significantly lower low density lipoprotein
cholesterol/high density lipoprotein cholesterol ratio of 2.26±0.6
for hyperresponders compared to 3.31±0.9 for hyporesponders. There
were also initial differences in the percentage of whole plasma
cholesterol found in the HDL fractions: hyperresponders had a
greater percentage of total and free cholesterol in the HDL and
HDL-2 fractions and a greater percentage of total cholesterol in the
HDL-3 fraction. The present data demonstrate that increased
cholesterol consumption will increase plasma cholesterol levels and
that there is individual variability of plasma cholesterol response
as a result of feeding cholesterol. / Graduation date: 1984
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The rational design and synthesis of potential squalene synthase inhibitorsFairlamb, Ian J. S. January 2000 (has links)
No description available.
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Nutritional studies on dietary palm oil : its effects on some cardiovascular risk parameters and chemically induced carcinogenesisSundram, Kalyana January 1995 (has links)
No description available.
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Causal probabilistic network modelling of lipid and lipoprotein metabolismRees, Stephen Edward January 1994 (has links)
No description available.
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Sequence variation in the LDL receptor gene, and its effect on plasma lipid levelsGudnason, Vilmundur Gardar January 1995 (has links)
No description available.
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