| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Comparison of breast-feeding and formula feeding on intestinal and hepatic cholesterol metabolism in neonatal pigs Jones, P. J., N. Hrboticky, et al. (1990), Am J Clin Nutr 51(6): 979-84. Abstract: Infant formulas (IFs) contain reduced cholesterol concentrations compared with breast milk (SM); how neonatal cholesterol metabolism responds to this difference is largely unknown. The effect of exclusive feeding of SM vs low-cholesterol IF on intestinal and hepatic cholesterol concentrations and synthesis during early postnatal development were compared in piglets. Animals were killed at birth or on days 5, 10, 15, or 25 postpartum. Plasma cholesterol concentrations were higher in SM-fed than in IF-fed piglets on days 15 and 25. In intestine both HMG-CoA reductase activity and 3H2O incorporation rates into cholesterol were similar for both groups or reduced in the IF-fed group at days 15 and 25. In liver, HMG-CoA reductase activity was higher in IF-fed than in SM-fed piglets on days 5, 10, and 15. Results indicate that during the early postpartum period, response to lower cholesterol intakes with IF occurs by increasing hepatic sterol synthesis whereas intestinal synthesis is largely unaffected. |
| Comparison of calculated and direct low density lipoprotein cholesterol determinations in a routine laboratory Amayo, A. A. and S. Kirera (2004), East Afr Med J 81(3): 154-8. Abstract: BACKGROUND: Low density lipoprotein cholesterol (LDL-C) concentrations form the basis for treatment guidelines established for hyperlipidaemic patients. LDL-C concentrations are commonly calculated using the Friedwald formula (FF) which has several limitations. Recently, direct methods for LDL-C estimation have been developed which are suitable for routine laboratories. OBJECTIVE: To compare serum LDL-C concentrations determined by a direct assay and the Friedwald formula. DESIGN: Cross-sectional study. SETTING: Mater Hospital Laboratory, Nairobi, Kenya. METHODS: The clinical performance of the two methods was evaluated by analysing 211 fresh plasma samples from fasting adult patients. The samples were divided into four groups-normolipidaemic; and Types IIa, IIb and IV hyperlipidaemias. RESULTS: The Friedwald formula (FF) correlated best with the direct assay in the normolipidaemic samples (r = 0.879; y= 0.468 + 0.852x). Direct LDL-C values were significantly lower than the FF in the Type IIa hyperlipidaemia samples (paired differences 0.38 +/- 0.62). There was only 65% agreement between the two methods in the borderline high LDL-C group of the National Cholesterol Education Program (NCEP) classification (LDL-C 3.36-4.14 mmol/L). CONCLUSION: There is lack of agreement between the FF and the Abbott direct LDL-C assay. If the two methods are used interchangeably, there may be confusion in the classification and control of lipid lowering medication for patients with hyperlipidaemia. |
| Comparison of Chemcard cholesterol test and laboratory cholesterol measurements Gan, I. E. and G. M. Schier (1995), Aust N Z J Med 25(6): 716-9. Abstract: BACKGROUND: The Chemcard cholesterol test has been designed to estimate cholesterol levels in patients in General Practitioners' surgeries. The patients displaying elevated cholesterol levels may then be referred for a more accurate test at a recognised laboratory. AIMS: To compare the accuracy of the Chemcard cholesterol procedure with a standardised laboratory procedure for estimating cholesterol levels. METHODS: The Chemcard cholesterol procedure was applied to 200 subjects from the community, who were enrolled in a cardiovascular risk assessment programme. RESULTS: The correlation coefficient between the paired measurements was 0.83. The Chemcard cholesterol procedure gave slightly higher results than did the laboratory procedure as shown by the mean (+/-standard deviation) difference between the two methods of 0.16 +/- 0.58 mmol/L. CONCLUSIONS: The poor agreement between the two methods and the potential misclassification by Chemcard suggests that the Chemcard is not a reliable test system. The high level of risk group misclassification found in this study refutes the manufacturer's claims and does not eliminate the need for formal laboratory cholesterol measurement. |
| Comparison of children and coronary heart disease patients with low high density lipoprotein cholesterol levels Ohta, T., K. Saku, et al. (1998), Atherosclerosis 137(2): 321-8. Abstract: Low plasma high density lipoprotein cholesterol (HDL-C) is a major risk factor for coronary heart disease (CHD) in adults. In the field of pediatrics, subjects with low plasma HDL-C are often found among obese or dyslipidemic children. However, it is not clear whether low HDL-C in children should be considered a risk factor for CHD. The purpose of this study was to evaluate the risk for CHD in children with low HDL-C by comparing their lipid and apolipoprotein levels and physicochemical characteristics of their HDL with those of age-matched children with normal HDL-C and CHD patients with low HDL-C. Plasma lipids and apolipoproteins were measured in 206 dyslipidemic children (dyslipidemic), 65 obese children (obese), 93 CHD patients with low HDL-C (< 40 mg/dl) and 128 children with normal HDL-C (controls). To evaluate the physicochemical characteristics of HDL, molar and fractional esterification rates of cholesterol in plasma (MER(plasma) and FER(plasma)) and HDL (MER(HDL) and FER(HDL)) were determined in 128 children with normal HDL-C, 71 dyslipidemic, 33 obese and 93 CHD who allowed second blood samples to be taken. Compared to controls, children with low HDL-C showed atherogenic profiles of lipid and apolipoprotein levels and physicochemical characteristics of HDL (lower apo A-I, lower ratio of apo A-I to apo B and higher FER(HDL)). Therefore, the differences in lipid and apolipoprotein profiles between children with low HDL-C and CHD patients with low HDL-C were examined next. The two groups of subjects based on the HDL-C level (Group I: < 30 mg/dl, Group II 30 < or = HDL-C < 40 mg/dl) were studied. Compared to CHD, Group I children showed less atherogenic apolipoprotein profiles (lower apo B and higher ratio of apo A-I to apo B). Similar findings were also found in Group II children, but the differences were less prominent than those in Group I children. FER(HDL) in children with low HDL-C were similar to those in CHD. These findings suggest that the physicochemical characteristics of HDL in children with low HDL-C are similar to those in CHD, but the abnormalities of apo B-containing lipoproteins are milder than those in CHD patients. Thus, if further changes in the nature of apo B-containing lipoproteins could be prevented, children with low HDL-C might not become high risk for CHD in later life. |
| Comparison of cholesterol and sitosterol uptake in different brush border membrane models Compassi, S., M. Werder, et al. (1997), Biochemistry 36(22): 6643-52. Abstract: (I) There is little discrimination between cholesterol and the plant sterol sitosterol in the uptake at the brush border membrane (BBM). (II) This difference cannot account for the marked discrimination between cholesterol and sitosterol observed in the absorption of these two sterols by the small-intestinal epithelium. (III) This discrimination occurs during intracellular processing involving the esterification and incorporation into lipoprotein particles of the two sterols. This conclusion is based on a comparative study of sterol uptake by brush border membrane vesicles (BBMV) and sterol absorption by Caco-2 cells. (IV) The uptake of sitosterol by the BBM is energy-independent and facilitated in a manner analogous to cholesterol uptake Thurnhofer, H., & Hauser, H. (1990a) Biochemistry 29, 2142-2148. (V) The rate of cholesterol and sitosterol uptake by BBMV from both mixed bile salt micelles and small unilamellar vesicles (SUV) as the donor is directly proportional to the sterol content of the donor. (VI) The pseudo-first-order rate constants k1 for sterol uptake from SUV are independent of the sterol content up to 10-20 mol %. Above that, competition between the two sterols leads to a reduction of the k1 values. |
| Comparison of cholesterol in habitually high and low active school-age children Blessing, D. L., H. T. Ford, Jr., et al. (1993), Percept Mot Skills 76(1): 18. Abstract: While risk-factor screening programs for coronary artery disease have been effective among adults, few programs are available for school-age children. 31 children were screened (16 active and 15 inactive) for cholesterol levels. The physically active group had a nonsignificantly lower mean which may reflect the small sample. |
| Comparison of cholesterol oxidation product preparation methods for subsequent gas chromatographic analysis Rodriguez-Estrada, M. T., A. Costa, et al. (2004), J AOAC Int 87(2): 474-80. Abstract: An evaluation was made of the stability of cholesterol hydroperoxides (CHPs) under the analytical conditions and preparation methods commonly used for determination and quantification of cholesterol oxidation products (COPs). CHPs were prepared by photoxidation and separated by silica thin-layer chromatography. CHPs were individually collected by normal-phase liquid chromatography and then subjected either to reduction or to cold saponification. The corresponding hydroxyl derivatives were generated by reduction, whereas cold saponification gave rise predominantly to 7-ketocholesterol. In another test, silylated and non-silylated CHPs were separately injected into a gas chromatograph at 310 degrees C, collected, and re-injected into a gas chromatography-mass spectrometry system. The silylated CHPs were more stable than the non-silylated ones, giving 7-ketocholesterol, 7alpha- and 7beta-hydroxycholesterol as main degradation products. Two unknown degradation peaks were detected in both silylated and nonsilylated CHPs, having 384 as main m/z fragment. The study of their mass spectra led to the conclusion that peaks A and B correspond to 6alpha- and 6beta-hydroxycholesterol, respectively. |
| Comparison of cholesterol-lowering efficacy and anti-atherogenic properties of hydrogenated versus non-hydrogenated (Phytrol) tall oil-derived phytosterols in apo E-deficient mice Pritchard, P. H., M. Li, et al. (2003), Cardiovasc Drugs Ther 17(5-6): 443-9. Abstract: The cholesterol-lowering and anti-atherogenic effects of non-hydrogenated (FCP-3P1 containing 69% beta-sitosterol, 16% sitostanol, and 13% campesterol) and hydrogenated (FCP-3P2 containing 77% sitostanol, 11% campestanol, and 8% beta-sitosterol) Phytrol trade mark have been compared in apo E-deficient mice. After consumption of 0.2% (w/w) cholesterol-enriched diet, the elevated plasma cholesterol levels observed in controls was significantly reduced by the addition of either 0.5%, 1% or 2% FCP-3P1 or FCP-3P2 at week 4. Compared to controls, the treatment of 0.5%, 1%, and 2% FCP-3P1 in the diet resulted in reduction in cholesterol concentrations by 33.6%, 46.8% and 52.4% at week 8, respectively, whereas the reduction in plasma cholesterol levels by 0.5%, 1%, and 2% FCP-3P2 was only 20.5%, 38.7% and 31.7% indicating lower cholesterol-lowering effect of the hydrogenated phytosterols at all doses as compared with non-hydrogenated phytosterols (FCP-3P1). By contrast, FCP-3P1 and FCP-3P2 showed comparable non-significant anti-atherogenic properties in treated animals after 14-week treatment. 0.5%, 1%, and 2% FCP-3P1 treated apo E-deficient mice had a mean aortic lesion area that was smaller than controls although the reduction of atherosclerotic lesions did not reach the statistical significance. In conclusion, this study did not show statistically significant differences between hydrogenated and non-hydrogenated plant sterols with regard to their cholesterol-lowering and anti-atherosclerotic properties in apo E-KO mice. |
| Comparison of C-reactive protein and low-density lipoprotein cholesterol levels in the prediction of first cardiovascular events Ridker, P. M., N. Rifai, et al. (2002), N Engl J Med 347(20): 1557-65. Abstract: BACKGROUND: Both C-reactive protein and low-density lipoprotein (LDL) cholesterol levels are elevated in persons at risk for cardiovascular events. However, population-based data directly comparing these two biologic markers are not available. METHODS: C-reactive protein and LDL cholesterol were measured at base line in 27,939 apparently healthy American women, who were then followed for a mean of eight years for the occurrence of myocardial infarction, ischemic stroke, coronary revascularization, or death from cardiovascular causes. We assessed the value of these two measurements in predicting the risk of cardiovascular events in the study population. RESULTS: Although C-reactive protein and LDL cholesterol were minimally correlated (r=0.08), base-line levels of each had a strong linear relation with the incidence of cardiovascular events. After adjustment for age, smoking status, the presence or absence of diabetes mellitus, categorical levels of blood pressure, and use or nonuse of hormone-replacement therapy, the relative risks of first cardiovascular events according to increasing quintiles of C-reactive protein, as compared with the women in the lowest quintile, were 1.4, 1.6, 2.0, and 2.3 (P<0.001), whereas the corresponding relative risks in increasing quintiles of LDL cholesterol, as compared with the lowest, were 0.9, 1.1, 1.3, and 1.5 (P<0.001). Similar effects were observed in separate analyses of each component of the composite end point and among users and nonusers of hormone-replacement therapy. Overall, 77 percent of all events occurred among women with LDL cholesterol levels below 160 mg per deciliter (4.14 mmol per liter), and 46 percent occurred among those with LDL cholesterol levels below 130 mg per deciliter (3.36 mmol per liter). By contrast, because C-reactive protein and LDL cholesterol measurements tended to identify different high-risk groups, screening for both biologic markers provided better prognostic information than screening for either alone. Independent effects were also observed for C-reactive protein in analyses adjusted for all components of the Framingham risk score. CONCLUSIONS: These data suggest that the C-reactive protein level is a stronger predictor of cardiovascular events than the LDL cholesterol level and that it adds prognostic information to that conveyed by the Framingham risk score. |
| Comparison of deuterium incorporation and mass isotopomer distribution analysis for measurement of human cholesterol biosynthesis Di Buono, M., P. J. Jones, et al. (2000), J Lipid Res 41(9): 1516-23. Abstract: To compare endogenous cholesterol biosynthesis measured by deuterium incorporation (DI) and mass isotopomer distribution analysis (MIDA), cholesterol fractional and absolute synthetic rates were measured simultaneously by both techniques under identical physiological conditions. Twelve subjects (22 to 39 years of age) underwent a dual stable isotope protocol, involving oral deuterium oxide administration and measurement of incorporation of deuterium into cholesterol coincident with constant infusion of sodium 1-(13)Cacetate and measurement of the mass isotopomer distribution pattern of newly synthesized cholesterol. Synthesis was determined over 24 h with a 7-h feeding period. Both methods yielded similar measurements of fractional cholesterol synthesis (7.8 +/- 2.5% day(-)(1) for DI vs. 6.9 +/- 2.2% day(-)(1) for MIDA). Correlation of fractional synthesis across techniques was strong (r = 0.84, P = 0.0007). Absolute synthesis rates were also not different at 24 h (13.4 +/- 4.3 mg kg(-)(1) day(-)(1) for DI vs. 11.9 +/- 3.6 mg kg(-)(1) day(-)(1) for MIDA, r = 0.79, P < 0.002).We conclude that despite different assumptions and analytical requirements, deuterium incorporation and MIDA yield similar rates of cholesterogenesis in humans when measurements are made over 24 h. The decision as to which method to adopt depends on available clinical and analytical facilities |
| Comparison of direct methods and HPLC for the measurement of HDL- and LDL-cholesterol with ultracentrifugation Yoshida, A., M. Naito, et al. (2001), J Atheroscler Thromb 8(3): 84-90. Abstract: Although ultracentrifugation is the gold standard for lipoprotein analysis, inexpensive and easy direct methods for HDL- and LDL-cholesterol (C) have recently been developed. In this study, we compared representative methods of lipoprotein analysis, namely, ultracentrifugation, direct assay methods, and HPLC, to measure LDL- and HDL-C. A good correlation was observed between HDL-C by ultracentrifugation and HDL-C by direct methods or HPLC. A good correlation was also observed between LDL-C (d1.006-1.063) by ultracentrifugation and LDL-C by direct methods or HPLC. Although the correlation between LDL-C (d1.019-1.063) by ultracentrifugation and LDL-C by direct methods was also good, the correlation coefficient was significantly decreased, suggesting that 'LDL-C' by direct methods correlates better with LDL-C (d1.006-1.063) than LDL-C (d1.019-1.063) by ultracentrifugation. Although the correlation between IDL-C (d1.006-1.019) by ultracentrifugation and the difference in LDL-C by direct methods and LDL-C (d1.019-1.063) by ultracentrifugation was investigated, no significant correlation was observed. The IDL-C contained in LDL-C (d1.006-1.063) varied from 2-28%. In homozygous CETP-deficient and LCAT-deficient subjects, the dissociation was marked. It is crucial to understand that 'LDL-C' in the Guidelines for the Diagnosis and Treatment of Hyperlipidemias in Adults by the Japanese Atherosclerosis Society should be considered to be LDL-C (d1.006-1.063) and that 'LDL-C' by direct assay methods means LDL-C (d1.006-1.063) by ultracentrifugation. |
| Comparison of effects of simvastatin versus atorvastatin on high-density lipoprotein cholesterol and apolipoprotein A-I levels Kastelein, J. J., J. L. Isaacsohn, et al. (2000), Am J Cardiol 86(2): 221-3. |
| Comparison of effects on low-density lipoprotein cholesterol and high-density lipoprotein cholesterol with rosuvastatin versus atorvastatin in patients with type IIa or IIb hypercholesterolemia Davidson, M., P. Ma, et al. (2002), Am J Cardiol 89(3): 268-75. Abstract: This randomized, double-blind, placebo-controlled trial was conducted in 52 centers in North America to compare the effects of the new, highly effective statin, rosuvastatin, with atorvastatin and placebo in hypercholesterolemic patients. After a 6-week dietary run-in, 516 patients with low-density lipoprotein (LDL) cholesterol > or =4.14 mmol/L (160 mg/dl) and < 6.47 mmol/L (250 mg/dl) and triglycerides < or =4.52 mmol/L (400 mg/dl) were randomized to 12 weeks of once-daily placebo (n = 132), rosuvastatin 5 mg (n = 128), rosuvastatin 10 mg (n = 129), or atorvastatin 10 mg (n = 127). The primary efficacy end point was percent change in LDL cholesterol. Secondary efficacy variables were achievement of National Cholesterol Education Program (NCEP) Adult Treatment Panel II (ATP II), ATP III, and European Atherosclerosis Society LDL cholesterol goals and percent change from baseline in high-density lipoprotein (HDL) cholesterol, total cholesterol, triglycerides, non-HDL cholesterol, apolipoprotein B, and apolipoprotein A-I. Rosuvastatin 5 and 10 mg compared with atorvastatin 10 mg were associated with greater LDL cholesterol reductions (-40% and -43% vs 35%; p <0.01 and p <0.001, respectively) and HDL cholesterol increases (13% and 12% vs 8%, p <0.01 and p <0.05, respectively). Total cholesterol and apolipoprotein B reductions and apolipoprotein A-I increases were also greater with rosuvastatin; triglyceride reductions were similar. Rosuvastatin 5 and 10 mg were associated with improved achievement in ATP II (84% in both rosuvastatin groups vs 73%) and ATP III (84% and 82% vs 72%) LDL cholesterol goals, and rosuvastatin 10 mg was more effective than atorvastatin in achieving European Atherosclerosis Society LDL cholesterol goals. Both treatments were well tolerated. |
| Comparison of exercise and normal variability on HDL cholesterol concentrations and lipolytic activity Gordon, P. M., P. S. Visich, et al. (1996), Int J Sports Med 17(5): 332-7. Abstract: In order to compare the influence of a single bout of exercise on HDL-C metabolism with normal variability, 12 male runners (mean age: 24.9 +/- 4 yr) who ran 15-30 miles per week underwent exercise (E) and control (C) experimental conditions. During the E trial subjects ran on a motor driven treadmill at 75% (42.5 +/- 4.7 ml.kg-1.min-1) VO2max until 800 Kcals were expended. The C trial consisted of no exercise. Subjects were instructed to follow the same diet and keep a four d food diary during each experimental condition. Fasted blood samples were obtained at the same time of day in each condition at time points corresponding to 24 h pre-exercise (24 PRE), 6 h post- (6 h) and 24 h post-exercise (24 h). Plasma was analyzed for HDL-C, HDL2-C and HDL3-C (mg.dl-1). In addition post-heparin plasma samples were analyzed for lipoprotein lipase (LPL) and hepatic lipase (HL) activity (mumol.FFA-1.ml-1). All values were adjusted for changes in plasma volume and compared to Baseline. HDL-C levels were unaltered following the C trial. However, following the E trial, HDL-C increased (p < 0.01) above baseline values at 24 h. The increase in HDL-C was reflected in the HDL3-C subfraction (p < 0.05). Analysis of lipolytic activity revealed an overall greater LPL activity (p < 0.05) in the E trial vs the C trial. In addition, a decrease in HL was observed at 24 h (p < 0.05) but was not different between experimental conditions. These data suggest that exercise and not normal variability are responsible for alterations in lipolytic activity and corresponding increases in HDL-C levels. |
| Comparison of flow-mediated dilatation of the brachial artery in coronary patients with low-density lipoprotein cholesterol levels <80 mg/dl versus patients with levels 80 to 100 mg/dl Kuvin, J. T., A. R. Patel, et al. (2005), Am J Cardiol 95(1): 93-5. Abstract: Testing of peripheral vascular endothelial function was performed in subjects who had coronary artery disease and a low-density lipoprotein (LDL) cholesterol level <100 mg/dl. LDL cholesterol was an independent predictor of flow-mediated dilation of the brachial artery (p = 0.010). The 63 subjects who had an LDL cholesterol level <80 mg/dl had better endothelial function (flow-mediated dilation 8.4 +/- 3.8%) than did 47 subjects whose level of LDL cholesterol was 80 to 100 mg/dl (flow-mediated dilation 6.8 +/- 4.0%, p = 0.03). The beneficial effects of LDL cholesterol levels <80 mg/dl on endothelial function were more apparent in subjects who had low levels of high-density lipoprotein cholesterol than in those who had normal levels. These data support recent reports that decreasing levels of LDL cholesterol below those currently recommended provides additional benefits and suggest that this benefit may be due in part to increased endothelial function. |
| Comparison of gas chromatography and liquid chromatography mass spectrometric measurements for high accuracy analysis of cholesterol in human serum by isotope dilution mass spectrometry Briche, C. S., D. Carter, et al. (2002), Rapid Commun Mass Spectrom 16(9): 848-53. Abstract: Cholesterol measurements are of vital clinical importance and reliable reference materials are essential for method validation. Gas chromatography with mass spectrometry (GC/MS) is usually used for the high accuracy analysis of cholesterol by isotope dilution. A certified reference material for cholesterol content in human serum was analysed by isotope dilution utilising GC/MS and liquid chromatography mass spectrometry (LC/MS). The use of LC/MS avoided the need for a derivatisation step. Both LC/MS and GC/MS produced results on the measurement of cholesterol that agreed within 0.5% of the certified value. Moreover, the precision obtained for ratio measurement using both techniques are comparable and lead to relative expanded standard uncertainties (with a coverage factor of 2) varying between 0.2 and 0.5%. |
| Comparison of gel permeation chromatography, density gradient ultracentrifugation and precipitation methods for quantitation of very-low-, low- and high-density lipoprotein cholesterol Nyyssonen, K. and J. T. Salonen (1991), J Chromatogr 570(2): 382-9. Abstract: Human VLDL, LDL and HDL (very-low-, low-, and high-density lipoproteins) were isolated from plasma by gel permeation chromatography with one pre-ultracentrifugation step. The column effluent was monitored at 280 nm. The cholesterol content of the fractions correlated well with fractions from sequential ultracentrifugation (VLDL, r = 0.839; LDL, r = 0.924; HDL, r = 0.766) or precipitation (LDL, r = 0.975; HDL, r = 0.972) methods. The average triglyceride, phospholipid and protein compositions of the separated lipoprotein fractions were close to those of the ultracentrifugally isolated fractions reported previously. Apolipoproteins A1 and B were determined from fractions to confirm the right distribution between different lipoproteins. |
| Comparison of gemfibrozil and lovastatin in patients with high low-density lipoprotein and low high-density lipoprotein cholesterol levels McKenney, J. M., M. D. Barnett, et al. (1992), Arch Intern Med 152(9): 1781-7. Abstract: BACKGROUND--The efficacy of gemfibrozil and lovastatin in the treatment of patients who have an elevated low-density lipoprotein cholesterol (LDL-C) level and a low high-density lipoprotein cholesterol (HDL-C) level was compared. METHODS--After at least 6 weeks of a cholestgerol-lowering diet, 17 patients who had a mean baseline LDL-C level above 4.14 mmol/L (160 mg/dL) and an HDL-C level below 1.03 mmol/L (40 mg/dL) received gemfibrozil 600 mg twice daily and lovastatin 20 mg twice daily each for 6 weeks according to a randomized, crossover, double-blind research design. RESULTS--Lovastatin and gemfibrozil reduced LDL-C levels 34% and 9% and raised HDL-C levels 15% and 18%, respectively. CONCLUSIONS--Lovastatin is more effective in lowering LDL-C levels and is as effective as gemfibrozil in increasing HDL-C levels in these patients. |
| Comparison of haptoglobin and apolipoprotein A-I on biliary lipid particles involved in cholesterol crystallization Yamashita, G., R. Secknus, et al. (1996), J Gastroenterol Hepatol 11(8): 738-45. Abstract: Several proteins are known to modulate cholesterol crystallization. We recently demonstrated that haptoglobin has cholesterol crystallization promoting activity. However, this effect is still not well understood mechanistically. The current study examined the distribution of haptoglobin compared to apolipoprotein A-I (apo A-I) to micelles, vesicles and crystals as an initial step in providing a focus for further studies of the mechanism of cholesterol crystallization activity. Specific protein purification was accomplished by immunoaffinity chromatography. The crystallization-promoting activity of biliary haptoglobin, albumin and commercial apo A-I was measured by a photometric crystal growth assay. The distribution of micelles, vesicles and proteins in model bile was determined by Sepharose CL-6B column chromatography. Detection of the presence of test proteins in cholesterol crystals was determined using specific 125I-radiolabelled proteins. Haptoglobin (20 micrograms/mL) showed a significant crystallization promoting-activity, whereas apo A-I (30 micrograms/mL) only tended to show a slight inhibitory activity. The cholesterol crystal-bound protein in each case was found to be less than 1% of the total concentration of that protein that had been added to the model bile system. The elution profile of commercial apo A-I from a Sepharose CL-6B column was strikingly altered when it was added to model bile prior to elution. In contrast, the column elution profiles for both haptoglobin and albumin were unchanged when model bile was similarly added to the sample. Haptoglobin increased the amount of cholesterol found in the vesicular fraction when compared to apo A-I. Haptoglobin does not bind tightly to either biliary lipid particles or to cholesterol crystals but does increase the amount of cholesterol in vesicles by inducing a shift from micellar cholesterol (P = 0.046). This shift appears to explain in part its promoting effect on cholesterol crystallization. |
| Comparison of high-density and low-density lipoprotein cholesterol subclasses and sizes in Asian Indian women with Caucasian women from the Framingham Offspring Study Bhalodkar, N. C., S. Blum, et al. (2005), Clin Cardiol 28(5): 247-51. Abstract: BACKGROUND: Asian Indian women have a higher rate of coronary artery disease (CAD) than do other ethnic groups, despite similar conventional risk factors and lipid profiles. Smaller high-density lipoprotein cholesterol (HDL-C) particle size is associated with reduced cardiac protection or even an increased risk of CAD. Exceptional longevity correlates better with larger HDL-C particle sizes. HYPOTHESIS: Higher rates of CAD among Asian Indian women may partly be explained by the differenes in the prevalence of atherogenic HDL-C and low-density lipoprotein cholesterol (LDL-C) sizes and their subclass concentrations among Asian Indian women compared with Caucasian women. METHODS: We measured HDL-C concentrations and sizes by nuclear magnetic resonance spectroscopy in 119 relatively healthy Asian Indian women and compared them with those of 1752 Caucasian women from the Framingham Offspring Study (FOS). RESULTS: Asian Indian women were significantly younger (47.9 +/- 11.2 vs. 51.0 +/- 10.1 years, p = 0.0001), leaner (body mass index 24.0 +/- 4.7 vs. 26.0 +/- 5.6, p = < 0.0002), less likely to be postmenopausal (32 vs. 54%, p = < 0.0001), or smoke (< 1 vs. 20%, p = < 0.0001); nevertheless, prevalence of CAD was higher in Asian Indian women (4.2 vs. 1%, p = 0.0006). Asian Indian women had similar HDL-C (53 +/- 13 vs. 53 +/- 13 mg/dl, p = 0.99), smaller HDL-C particle size (8.9 +/- 0.35 vs. 9.4 +/- 0.44 nm, p = < 0.0001), higher total cholesterol (209 +/- 40 vs. 199 +/- 42 mg/dl, p = 0.01), and similar triglyceride (120 +/- 77 vs. 108 +/- 110 mg/d, p = 0.24) levels. Low-density lipoprotein cholesterol, particle concentrations and sizes, as well as prevalence of pattern B were similar. CONCLUSIONS: Compared with the FOS, Asian Indian women have significantly smaller overall HDL particle size and similar levels of HDL-C, which may reflect impaired, reverse cholesterol transport. Total cholesterol was higher, whereas triglyceride and LDL-C levels were similar. This may partly explain the higher CAD rates in Asian Indian women. Further large scale, prospective, long-term studies are warranted. |