Cholesterol Journal Articles

Record 5721 to 5740

Egg consumption, serum cholesterol, and cause-specific and all-cause mortality: the National Integrated Project for Prospective Observation of Non-communicable Disease and Its Trends in the Aged, 1980 (NIPPON DATA80)
Nakamura, Y., T. Okamura, et al. (2004), Am J Clin Nutr 80(1): 58-63.
Abstract: BACKGROUND: Because egg yolk has a high cholesterol concentration, limited egg consumption is often suggested to help prevent ischemic heart disease (IHD). OBJECTIVE: We epidemiologically examined the validity of this recommendation. DESIGN: We analyzed the relations of egg consumption to serum cholesterol and cause-specific and all-cause mortality by using the NIPPON DATA80 (National Integrated Project for Prospective Observation of Non-communicable Disease And its Trends in the Aged, 1980) database. At the baseline examination in 1980, a nutritional survey was performed by using the food-frequency method in Japanese subjects aged > or =30 y. We followed 5186 women and 4077 men for 14 y. RESULTS: The subjects were categorized into 5 egg consumption groups on the basis of their responses to a questionnaire (> or =2/d, 1/d, 1/2 d, 1-2/wk, and seldom). There were 69, 1396, 1667, 1742, and 315 women in each of the 5 groups, respectively. Age-adjusted total cholesterol (5.21, 5.04, 4.95, 4.91, and 4.92 mmol/L in the 5 egg consumption categories, respectively) was related to egg consumption (P < 0.0001, analysis of covariance). In women, unadjusted IHD mortality and all-cause mortality differed significantly between the groups IHD mortality: 1.1, 0.5, 0.4, 0.5, and 2.0 per 1000 person-years, respectively (P = 0.008, chi-square test); all-cause mortality: 14.8, 8.0, 7.5, 7.5, and 14.5 per 1000 person-years, respectively (P < 0.0001, chi-square test). In men, egg consumption was not related to age-adjusted total cholesterol. Cox analysis found that, in women, all-cause mortality in the 1-2-eggs/wk group was significantly lower than that in the 1-egg/d group, whereas no such relations were noted in men. CONCLUSION: Limiting egg consumption may have some health benefits, at least in women in geographic areas where egg consumption makes a relatively large contribution to total dietary cholesterol intake.

Egg ovomucin attenuates hypercholesterolemia in rats and inhibits cholesterol absorption in Caco-2 cells
Nagaoka, S., M. Masaoka, et al. (2002), Lipids 37(3): 267-72.
Abstract: This experiment was designed to evaluate the effect of casein or ovomucin (OV) on the micellar solubility of cholesterol and the taurocholate binding capacity in vitro. We also evaluated the effects of casein or OV on cholesterol metabolism in rats and Caco-2 cells. OV had a significantly greater bile acid-binding capacity than that of casein in vitro. Micellar cholesterol solubility in vitro was significantly lower in the presence of OV compared to casein. The cholesterol micelles containing OV significantly suppressed cholesterol uptake by Caco-2 cells compared to the cholesterol micelles containing casein. Consistent with these in vitro findings, OV-feeding significantly increased the fecal excretion of bile acids or cholesterol compared with casein-feeding. Serum total cholesterol was significantly lower in rats fed OV than in those fed casein. The concentrations of total lipids in liver were significantly lower in the OV-fed group compared with the casein group. These results suggest that the suppression of cholesterol absorption by direct interaction between cholesterol mixed micelles and OV in the jejunal epithelia is part of the mechanism underlying the hypocholesterolemic action of OV. OV may also inhibit the reabsorption of bile acids in the ileum, thus lowering the serum cholesterol level.

Egg phosphatidylcholine decreases the lymphatic absorption of cholesterol in rats
Jiang, Y., S. K. Noh, et al. (2001), J Nutr 131(9): 2358-63.
Abstract: This study was conducted to determine the effects of phosphatidylcholine (PC) from different sources on intestinal absorption of cholesterol. Male Sprague-Dawley rats were fed an AIN-93G diet containing soybean oil for 4 wk. Each rat with lymph cannula was infused via a duodenal catheter at 3.0 mL/h for 8 h with a lipid emulsion in micromol: 451.8 triolein, 27.8 kBq 14C-cholesterol (CH), 20.7 CH, 3.6 alpha-tocopherol, and 100 PC in 24 mL PBS, pH 6.6. The PC in the lipid emulsion was egg PC (EPC), hydrogenated egg PC (HPC), or soy PC (SPC). The EPC in the lipid emulsion markedly lowered the lymphatic absorption of 14C-CH (24.7 +/- 2.5% dose) compared with SPC (34.9 +/- 1.2%) and a lipid emulsion containing no PC (NPC) (30.8 +/- 2.0%). The HPC further lowered the absorption of 14C-CH to 21.1 +/- 1.4% dose. The outputs of phospholipid were unaffected by the source of PC infused (EPC, 32.2 +/- 1.7; HPC, 31.8 +/- 1.6; and SPC, 32.9 +/- 1.8 micromol/8 h). Compared with NPC (595.0 +/- 59.5 micromol), the total output of fatty acids over 8 h was increased significantly by SPC (685.4 +/- 55.8 micromol), but decreased by HPC (467.7 +/- 28.4 micromol). The total lymphatic output of oleic acid (18:1), the major fatty acid infused in the form of triolein, did not differ among the NPC (448.0 +/- 58.2 micromol/8 h), SPC (457.9 +/- 52.3 micromol/8 h) and EPC (412.9 +/- 20.8 micromol/8 h) groups, but was significantly lower in the HPC group (262.0 +/- 24.1 micromol/8 h). The findings provide the first evidence that EPC markedly lowers the lymphatic absorption of cholesterol under in vivo conditions. The inhibitory effect of EPC appears to be due to the higher degree of saturation of its acyl groups relative to SPC, suggesting that the intestinal absorption of egg cholesterol may be reduced by the presence of PC in egg yolk.

Egg sphingomyelin lowers the lymphatic absorption of cholesterol and alpha-tocopherol in rats
Noh, S. K. and S. I. Koo (2003), J Nutr 133(11): 3571-6.
Abstract: Evidence indicates that phosphatidylcholine (PC) inhibits the intestinal absorption of cholesterol (CH) in rats. This study was designed to determine whether sphingomyelin (SM), structurally similar to PC, also inhibits the lymphatic absorption of CH. Sprague-Dawley rats with lymph cannulae were infused at 3.0 mL/h for 8 h via a duodenal catheter with a lipid emulsion 33.3 kBq 14C-CH, 20.7 micromol CH, 451.7 micromol triolein, 3.1 micromol alpha-tocopherol (alphaTP), 75.4 nmol retinol and 396.0 micromol sodium taurocholate in 24 mL of PBS (pH, 6.5), without egg SM (SM0) as control, or with 5.0 micromol/h (SM5) or 10.0 micromol/h (SM10). Egg SM lowered the lymphatic absorption of 14C-CH in a dose dependent manner. Likewise, SM lowered the lymphatic absorptions of alphaTP and fatty acid (oleic acid), whereas it had no effect on retinol absorption. SM at a high dose (SM10) lowered the lymphatic outputs of both PC and SM, whereas there was no such effect at a lower dose (SM5). These results indicate that luminal egg SM has an inhibitory effect on the intestinal absorption of CH and other lipids of relatively high hydrophobicity. Our findings suggest that SM, if ingested in sufficient amounts, may inhibit the intestinal absorption of dietary lipids including cholesterol and alphaTP.

Eggs and cholesterol--was the message of the editorial correctly interpreted?
Uusitupa, M. and E. Sarkkinen (2000), Duodecim 116(6): 628-31.

Eggs for breakfast: recalling the cholesterol debates
Anderson, P. C. and M. A. Flynn (1999), Mo Med 96(9): 443-6.

Ehrlichia chaffeensis and Anaplasma phagocytophilum lack genes for lipid A biosynthesis and incorporate cholesterol for their survival
Lin, M. and Y. Rikihisa (2003), Infect Immun 71(9): 5324-31.
Abstract: Ehrlichia chaffeensis and Anaplasma phagocytophilum are agents of human monocytic and granulocytic ehrlichioses, respectively. They are extremely sensitive to mechanical stress and are pleomorphic gram-negative bacteria. Membrane incorporation of cholesterol from the eukaryotic host is known to be essential for other fragile and pleomorphic bacteria and mycoplasmas that lack a cell wall. Thus, we tested whether cholesterol is required for E. chaffeensis and A. phagocytophilum. Using a freeze fracture technique and biochemical analysis, these bacteria were found to contain significant levels of membrane cholesterol. These bacteria lack genes for cholesterol biosynthesis or modification. However, host cell-free bacteria had the ability to take up directly exogenous cholesterol or NBD-cholesterol, a fluorescent cholesterol derivative. Treatment of the bacteria with cholesterol extraction reagent methyl-beta-cyclodextrin caused their ultrastructural changes. Furthermore, pretreatment of the bacteria with methyl-beta-cyclodextrin or NBD-cholesterol deprived these bacteria of the ability to infect leukocytes, thus killing these obligate intracellular bacteria. Analysis of E. chaffeensis and A. phagocytophilum genome sequences revealed that these bacteria lack all genes for the biosynthesis of lipid A and most genes for the biosynthesis of peptidoglycan, which confer structural strength to gram-negative bacteria. Taken together, these results suggest that human ehrlichiosis agents became cholesterol dependent due to the loss of these genes. As the first report of gram-negative bacteria incorporating cholesterol for survival, these findings offer insight into the unique nature of their parasitism and imply that cholesterol is important in the control of human ehrlichioses.

Eicosanoid metabolism in cholesterol-enriched arterial smooth muscle cells. Evidence for reduced posttranscriptional processing of cyclooxygenase I and reduced cyclooxygenase II gene expression
Pomerantz, K. B., B. Summers, et al. (1993), Biochemistry 32(49): 13624-35.
Abstract: Eicosanoid biosynthetic activity by the cyclooxygenase pathway is reduced in smooth muscle cell-derived foam cells Pomerantz, K.B., & Hajjar, D.P. (1989) J. Lipid Res. 30, 1219-1231; Pomerantz, K.B., & Hajjar, D.P. (1990) Biochemistry 29, 1892-1899. The present study identifies those mechanisms which contribute to reduced production of cyclooxygenase products following cholesterol enrichment of arterial smooth muscle cells. Cyclooxygenase activity, as assessed by the conversion of exogenous arachidonate to 6-keto-PGF1 alpha, was reduced approximately 8-fold in intact lipid-laden cells relative to untreated cells. Microsomes from cholesterol-enriched cells also converted less 3Harachidonic acid to 6-keto-PGF1 alpha and PGE2 relative to microsomes from untreated cells. The reduction in cyclooxygenase activity paralleled the reduced mass of the constitutive form of cyclooxygenase (COX-1) and PGI2 synthase by approximately 80% and 33%, respectively. Northern blot hybridization analyses of COX-1 mRNA steady-state levels revealed no differences between normal and cholesterol-enriched cells under basal conditions, indicating that cholesterol enrichment did not alter COX-1 gene expression. Furthermore, cholesterol enrichment did not alter the relative levels of COX-1 mRNA expression over time following exposure of the cells to actinomycin D, indicating that cholesterol enrichment did not significantly alter the rate of COX-1 mRNA degradation. Recovery of PGI2 biosynthesis in untreated cells exposed to serum following the inactivation of COX occurred within 12 h, while the recovery of COX activity in lipid-enriched cells did not return to levels observed in untreated cells even after up to 48 h, suggesting that the induction of COX-2 (inducible form of cyclooxygenase) synthesis by growth factors or cytokines is impaired. Indeed, cholesterol enrichment attenuated IL-1 beta-, PDGF-, and TNF alpha-induced PGI2 synthesis relative to controls and was consistent with the results of in vitro labeling experiments demonstrating that cholesterol enrichment reduced the incorporation of 35Smethionine into immunoprecipitable COX-1 and COX-2 following induction by PDGF. Cholesterol enrichment also reduced the induction of COX-2 mRNA steady-state levels following exposure to PDGF. Taken together, these data demonstrate that reduced eicosanoid synthesis in smooth muscle-derived foam cells is due, in part, to impaired transcription of mRNA for COX-1 and COX-2 as well as fatty acid remodeling in membrane phospholipids. These findings support the hypothesis that cholesterol enrichment alters posttranscriptional processing of COX-1 expression, as well as altering COX-2 gene expression.

Eicosapentaenoic acid abolishes the proatherogenic effects of cholesterol: effects on migration of bovine smooth muscle and endothelial cells in vitro
Kanayasu-Toyoda, T., I. Morita, et al. (1993), Prostaglandins Leukot Essent Fatty Acids 48(6): 463-8.
Abstract: It is well known that vascular endothelial cell (EC) migration plays a major role in regeneration of the injured endothelium and also that smooth muscle cell (SMC) migration is the important step for atheromatous plaque formation. In the present study, we investigated the effects of cholesterol and eicosapentaenoic acid (EPA) on bovine carotid artery EC and SMC migration using the modified Boyden chamber technique. The migration activity of the cholesterol-enriched ECs loaded with cholesterol-rich liposomes was significantly suppressed, whereas that of the cholesterol-enriched SMCs was enhanced. Next, we examined the effects of EPA pretreatment on the migration of both cell types. When ECs and SMCs were treated with EPA (5 micrograms/ml) for 2 days, the EPA content increased from 0.55 +/- 0.04% to 11.72 +/- 0.19% and 1.22 +/- 0.09% to 9.69 +/- 0.07% in cellular phospholipids, respectively. Although pretreatment of the ECs with EPA caused a significant increase in serum-induced cell migration, pretreatment of SMCs had no effect. If both cell types were concomitantly pretreated with EPA and cholesterol-rich liposomes, EPA abolished the effects of cholesterol on the migration of both cell types, but did not affect the content of cholesterol in both cells. These data indicate the possibility that EPA counteracts the atherogenic effect of cholesterol on EC and SMC migration.

Eicosapentanoic acid suppresses intimal hyperplasia after expanded polytetrafluoroethylene grafting in rabbits fed a high cholesterol diet
M, O. h., K. Esato, et al. (1991), J Vasc Surg 13(4): 480-6.
Abstract: The effect of purified eicosapentanoic acid on intimal fibrous hyperplasia in expanded polytetrafluoroethylene grafts was examined in 18 rabbits undergoing infrarenal aorta reconstruction. Six rabbits received commercial rabbit chow (control group), six a regular diet supplemented with 1% cholesterol (cholesterol group), and six the cholesterol diet with 91.1% pure eicosapentanoic acid 500 mg/day (eicosapentanoic acid group). Grafts were harvested 3 months after surgery for histologic examination. The platelet count and serum beta-thromboglobulin and platelet factor 4 concentrations were not significantly different between groups. Serum arachidonic acid level in the cholesterol group was significantly higher than in the control group, and serum eicosapentanoic acid levels in the eicosapentanoic acid group were significantly higher than in the remaining two groups. Intergroup differences in serum 6-keto-prostaglandin F1 alpha and thromboxane B2 concentrations were not significant. Intimal thickness at midgraft was 5.2 +/- 6.2 microns in the control group, 67.6 +/- 46.9 microns in the cholesterol group, and 19.2 +/- 18.4 microns in the eicosapntanoic acid group. intimal thickness in the cholesterol group was greater than in either the control or licosapentanoic acid group (p less than 0.01 and p less than 0.05, respectively). These data suggest that eicosapentanoic acid reduces intimal fibrous proliferation in expanded polytetrafluoroethylene grafting as a result of hypercholesterolemia and that this effect is independent of the platelet count, activated platelet factors, and the prostacyclin/thromboxane A2 ratio.

Eight compact analysis systems evaluated for measuring total cholesterol
Gregory, L. C., S. H. Duh, et al. (1994), Clin Chem 40(4): 579-85.
Abstract: We examined the analytical performance of eight compact systems for measuring total cholesterol: AccuMeter, Cobas Ready, Discovery f2, DT60, L-D-X, Reflotron, QCA, and Vision. We determined average bias at two decision levels, the mean absolute bias, and the percentage of results differing from the comparison method results by > 8.9% allowable total error limit for multiple reagent lots. Average bias was < 3% for all lots tested for AccuMeter, Discovery f2, and DT60, but > 3% for one or more lots or sample types tested with the other systems. Of results from each reagent lot, > 95% were within the 8.9% total error specifications with Discovery f2, DT60, and QCA, whereas the performance of L-D-X, Vision, and Reflotron depended on reagent lot and (or) sample type. Of all results from each lot tested with AccuMeter and Cobas Ready, > 5% exceeded the total allowable error limit. We determined imprecision for five systems: Cobas Ready, Discovery f2, and QCA had CVs < 3%, whereas CVs for AccuMeter and L-D-X were > 3% but < 5%.

Elastic deformation and failure of lipid bilayer membranes containing cholesterol
Needham, D. and R. S. Nunn (1990), Biophys J 58(4): 997-1009.
Abstract: Giant bilayer vesicles were reconstituted from several lipids and lipid/cholesterol (CHOL) mixtures: stearolyloleoylphosphatidylcholine (SOPC), bovine sphingomyelin (BSM), diarachidonylphosphatidylcholine (DAPC), SOPC/CHOL, BSM/CHOL, DAPC/CHOL, and extracted red blood cell (RBC) lipids with native cholesterol. Single-walled vesicles were manipulated by micropipette suction and several membrane material properties were determined. The properties measured were the elastic area compressibility modulus K, the critical areal strain alpha c, and the tensile strength tau lys, from which the failure energy or membrane toughness Tf was calculated. The elastic area expansion moduli for these lipid and lipid/cholesterol bilayers ranged from 57 dyn/cm for DAPC to 1,734 dyn/cm for BSM/CHOL. The SOPC/CHOL series and RBC lipids had intermediate values. The results indicated that the presence of cholesterol is the single most influential factor in increasing bilayer cohesion, but only for lipids where both chains are saturated, or mono- or diunsaturated. Multiple unsaturation in both lipid chains inhibits the condensing effect of cholesterol in bilayers. The SOPC/CHOL system was studied in more detail. The area expansion modulus showed a nonlinear increase with increasing cholesterol concentration up to a constant plateau, indicating a saturation limit for cholesterol in the bilayer phase of approximately 55 mol% CHOL. The membrane compressibility was modeled by a property-averaging composite theory involving two bilayer components, namely, uncomplexed lipid and a lipid/cholesterol complex of stoichiometry 1/1.22. The area expansion modulus of this molecular composite membrane was evaluated by a combination of the expansion moduli of each component scaled by their area fractions in the bilayer. Bilayer toughness, which is the energy stored in the bilayer at failure, showed a maximum value at approximately 40 mol% CHOL. This breakdown energy was found to be only a fraction of the available thermal energy, implying that many molecules (approximately 50-100) may be involved in forming the defect structure that leads to failure. The area expansion modulus of extracted RBC lipids with native cholesterol was compared with recent measurements of intact RBC membrane compressibility. The natural membrane was also modeled as a simple composite made up to a compressible lipid/cholesterol matrix containing relatively incompressible transmembrane proteins. It appears that the interaction of incompressible proteins with surrounding lipid confers enhanced compressibility on the composite structure.

Elastic free energy of anisotropic helical ribbons as metastable intermediates in the crystallization of cholesterol
Chung, D. S., G. B. Benedek, et al. (1993), Proc Natl Acad Sci U S A 90(23): 11341-5.
Abstract: We report measurements of the geometrical structure and temporal evolution of metastable helical intermediates in the pathway for cholesterol crystallization in native and model biles. We find that the lecithin component in the bile can dramatically affect the kinetics along this pathway. We also present a theoretical description of these helical intermediates using an elastic free energy appropriate for anisotropic bilayers of tilted chiral amphiphiles, which provides a quantitative description of the observed helical ribbon geometry and insight into the relative free energies of the observed metastable intermediates.

Electric field effect on cholesterol-phospholipid complexes
Radhakrishnan, A. and H. M. McConnell (2000), Proc Natl Acad Sci U S A 97(3): 1073-8.
Abstract: Monolayer mixtures of dihydrocholesterol and phospholipids at the air-water interface are used to model membranes containing cholesterol and phospholipids. Specific, stoichiometric interactions between cholesterol and some but not all phospholipids have been proposed to lead to the formation of condensed complexes. It is reported here that an externally applied electric field of the appropriate sign can destabilize these complexes, resulting in their dissociation. This is demonstrated through the application of an electric field gradient that leads to phase separations in otherwise homogeneous monolayers. This is observed only when the monolayer composition is close to the stoichiometry of the complex. The electric field effect is analyzed with the same mean field thermodynamic model as that used previously to account for pairs of upper miscibility critical points in these mixtures. The concentrations of dihydrocholesterol, phospholipid, and complex vary strongly and sometimes discontinuously in the monolayer membrane in the field gradient. The model is an approximation to a two-dimensional liquid in which molecules freely exchange between free and complexed form so that the chemical potentials are constant throughout the membrane. The calculations are illustrated for a complex of about 15 molecules, composed of 5 cholesterol molecules and 10 phospholipid molecules.

Electrocardiographic events and cholesterol reduction with pravastatin in patients with hypercholesterolemia: the Hokuriku Lipid Coronary Heart Disease Study-Pravastatin Atherosclerosis Trial
Shimizu, M., J. Koizumi, et al. (2005), Int J Cardiol 99(3): 395-401.
Abstract: BACKGROUND: Cholesterol lowering therapy may offset the development of coronary atherosclerosis, and the resulting reduction in coronary ischemia may be observed in the electrocardiogram (ECG). METHODS: A total of 2039 Japanese adults with hypercholesterolemia were divided into two groups (receiving 10-20 mg pravastatin daily or a normal diet) and were followed up for 5 years. ECG studies were performed at entry and every year during the follow-up period. The occurrence of myocardial infarction and the appearance or worsening of ischemic ST changes were assessed in terms of effects on the ECG. RESULTS: Of the 2039 patients registered, 827 were excluded from the study for various reasons. Consequently, a total of 1212 patients were analyzed. There was a lower degree of worsening in the pravastatin group (n=757) than in the normal diet group (n=455) in the primary prevention cohort 11 (1.8%) vs. 16 (4.3%), respectively, P=0.031. On the other hand, there was no difference in the frequency of worsening between the two groups in the secondary prevention cohort 7 (4.4%) in the pravastatin group vs. 4 (4.9%) in the diet group, P=0.25. Event-free survival was better in the pravastatin group than in the normal diet group in the primary prevention cohort (P=0.011), but there was no difference between the two groups in the secondary prevention cohort. CONCLUSIONS: These results suggest that pravastatin may reduce the incidence of coronary heart disease and that this effect may be predominantly observed in patients with early atheromatous lesions.

Electrochemical investigations of cholesterol enriched glassy carbon supported thin lipid films
Karabaliev, M. and V. Kochev (2003), Biophys Chem 103(2): 157-67.
Abstract: The formation and study of stable cholesterol enriched thin lipid layers onto the surface of glassy carbon electrode is reported in this work. The method of formation relies on additional thinning of wetting films by electrostriction. Electrochemical techniques based on the concepts of impedance and voltammetry are used to explore the films' features. The impedance data reveal a substantial change of relaxation characteristics of the modified films. In this respect, opportunities for the evaluation of the films' stage based on the approximation with 'constant phase angle element' are discussed. The possible final structure of the films, as well as, their relevance for development of sensor elements are briefly viewed.

Electron beam tomography and National Cholesterol Education Program guidelines in asymptomatic women
Hecht, H. S. and H. R. Superko (2001), J Am Coll Cardiol 37(6): 1506-11.
Abstract: OBJECTIVES: This investigation was designed to determine the relationship between National Cholesterol Education Program (NCEP) ATP-II lipid guidelines and subclinical atherosclerosis, defined by electron beam tomography (EBT) calcified coronary plaque, in asymptomatic women. BACKGROUND: NCEP guidelines are used to identify women at increased risk for coronary artery disease (CAD) on the basis of low density lipoprotein cholesterol (LDLC) and high density lipoprotein cholesterol (HDLC) values. The relationship of the guidelines to subclinical atherosclerosis is unknown. METHODS: A total of 304 asymptomatic women underwent lipid and EBT evaluation and were classified as: 1) NCEP higher risk, with LDLC > or =130 mg/dl and/or HDLC <35 mg/dl, or lower risk with LDLC <130 mg/dl and HDLC > or =35 mg/dl; and 2) EBT+ if any calcified plaque was noted or EBT- if there was no calcified plaque. RESULTS: Forty-two percent of patients were EBT+, with a mean score of 227 and percentile of 73%; 58% were EBT-. Women who were EBT+ had significantly higher total cholesterol, LDLC and triglycerides than EBT- women, but only with ages < or =55 years; women >55 years demonstrated no differences. NCEP higher risk women made up 53.5% of the EBT+ and 37.7% of the EBT- groups; NCEP lower risk women accounted for 46.5% of the EBT+ and 62.3% of the EBT- groups. Assuming a higher risk in subjects with EBT-defined subclinical CAD than in those without, only 58.6% of the total group would be correctly identified by NCEP guidelines as either higher or lower risk, with correct identification of 65.5% of the younger and 52.2% of the older women. There was no correlation between either calcium percentile or score and any lipid measurement. CONCLUSIONS: This study demonstrates the shortcomings of employing NCEP guidelines to identify asymptomatic women with subclinical CAD, particularly women >55 years, and suggests increased utilization of EBT for primary prevention in the female population.

Electron leakage from the mitochondrial NADPH-adrenodoxin reductase-adrenodoxin-P450scc (cholesterol side chain cleavage) system
Hanukoglu, I., R. Rapoport, et al. (1993), Arch Biochem Biophys 305(2): 489-98.
Abstract: In electron (e-) transfer systems some e- may "leak," reducing O2 to a superoxide radical. This study examined the sites and kinetics of e-leakage from the mitochondrial P450scc system. Adrenodoxin reductase alone oxidized NADPH, reducing O2 to a superoxide radical at a very low rate. However, the reductase-adrenodoxin system reduced O2 at a rapid steady-state rate with Michaelis-Menten dependence on adrenodoxin(Vmax = 3.5 micro M e-/min). After depletion of NADPH, reduced adrenodoxin was oxidized (autooxidation) with pseudo first order kinetics and the rate of e- transfer decreased 10-fold. Ca2+ (< 1 mM) stimulated e- leakage in both phases. The reductase-adrenodoxin-P450scc system exhibited the highest rate of leakage (Vmax = 7.8 microM e-/min). At low adrenodoxin the majority of e-leaked through P450scc and not through adrenodoxin. In the presence of the substrate, cholesterol, leakage drastically decreased to <0.5 microM e-/min. These results indicate that the mitochondrial P450 systems can leak e-, producing O2 derived free radicals. Reduction of leakage during P450scc conversion of cholesterol to pregnenolone provides a clue to understanding physiological mechanisms that control e-leakage. These may include coregulation of NADPH and cholesterol availability to the P450scc system and a system of antioxidants for quenching the oxygen radicals.

Electron microscope study of the interaction of DC-cholesterol containing liposomes and human erythrocytes
Tarakhovskii Iu, S. (1996), Biull Eksp Biol Med 122(7): 83-6.

Electron paramagnetic resonance studies of magnetically aligned phospholipid bilayers utilizing a phospholipid spin label: the effect of cholesterol
Dave, P. C., N. A. Nusair, et al. (2005), Biochim Biophys Acta 1714(2): 141-51.
Abstract: X-band EPR spectroscopy has been employed to study the dynamic properties of magnetically aligned phospholipid bilayers (bicelles) utilizing a variety of phosphocholine spin labels (n-PCSL) as a function of cholesterol content. The utilization of both perpendicular and parallel aligned bicelles in EPR spectroscopy provides a more detailed structural and orientational picture of the phospholipid bilayers. The magnetically aligned EPR spectra of the bicelles and the hyperfine splitting values reveal that the addition of cholesterol increases the phase transition temperature and alignment temperature of the DMPC/DHPC bicelles. The corresponding molecular order parameter, Smol, of the DMPC/DHPC bicelles increased upon addition of cholesterol. Cholesterol also decreased the rotational motion and increased the degree of anisotropy in the interior region of the bicelles. This report reveals that the dynamic properties of DMPC/DHPC bicelles agree well with other model membrane systems and that the magnetically aligned bicelles are an excellent model membrane system.

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