| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Cost-effectiveness of pravastatin therapy for survivors of myocardial infarction with average cholesterol levels Tsevat, J., K. M. Kuntz, et al. (2001), Am Heart J 141(5): 727-34. Abstract: BACKGROUND: The objective of this study was to assess the cost-effectiveness of pravastatin therapy in survivors of myocardial infarction with average cholesterol levels. METHODS: We performed a cost-effectiveness analysis based on actual clinical, cost, and health-related quality-of-life data from the Cholesterol and Recurrent Events (CARE) trial. Survival and recurrent coronary heart disease events were modeled from trial data in Markov models, with the use of different assumptions regarding the long-term benefit of therapy. RESULTS: Pravastatin therapy increased quality-adjusted life expectancy at an incremental cost of $16,000 to $32,000 per quality-adjusted life-year gained. In subgroup analyses, the cost-effectiveness of pravastatin therapy was more favorable for patients >60 years of age and for patients with pretreatment low-density lipoprotein cholesterol levels >125 mg/dL. Results were sensitive to the cost of pravastatin and to assumptions about long-term survival benefits from pravastatin therapy. CONCLUSIONS: The cost-effectiveness of pravastatin therapy in survivors of myocardial infarction with average cholesterol levels compares favorably with other interventions. |
| Coupling of cholesterol and cone-shaped lipids in bilayers augments membrane permeabilization by the cholesterol-specific toxins streptolysin O and Vibrio cholerae cytolysin Zitzer, A., R. Bittman, et al. (2001), J Biol Chem 276(18): 14628-33. Abstract: Vibrio cholerae cytolysin (VCC) forms oligomeric pores in lipid bilayers containing cholesterol. Membrane permeabilization is inefficient if the sterol is embedded within bilayers prepared from phosphatidylcholine only but is greatly enhanced if the target membrane also contains ceramide. Although the enhancement of VCC action is stereospecific with respect to cholesterol, we show here that no such specificity applies to the two stereocenters in ceramide; all four stereoisomers of ceramide enhanced VCC activity in cholesterol-containing bilayers. A wide variety of ceramide analogs were as effective as D-erythro-ceramide, as was diacylglycerol, suggesting that the effect of ceramide exemplifies a general trend of lipids with a small headgroup to augment the activity of VCC. Incorporation of these cone-shaped lipids into cholesterol-containing bilayers also gave similar effects with streptolysin O, another cholesterol-specific but structurally unrelated cytolysin. In contrast, the activity of staphylococcal alpha-hemolysin, which does not share with the other toxins the requirement for cholesterol, was far less affected by the presence of lipids with a conical shape. The collective data indicate that sphingolipids and glycerolipids do not interact with the cytolysins specifically. Instead, lipids that have a conical molecular shape appear to effect a change in the energetic state of membrane cholesterol that in turn augments the interaction of the sterol with the cholesterol-specific cytolysins. |
| Coupling the cholesterol- and tumor-suppressive actions of palm oil to the impact of its minor constituents on 3-hydroxy-3-methylglutaryl coenzyme A reductase activity Elson, C. E. and A. A. Qureshi (1995), Prostaglandins Leukot Essent Fatty Acids 52(2-3): 205-7. Abstract: The impact of palm oil on cardiovascular disease and cancer may be explained by the mevalonate-suppressive action of constituent isoprenoid end products of plant secondary metabolism. Assorted monoterpenes, sesquiterpenes, carotenoids and tocotrienols down regulate, post-transcriptionally, 3-hydroxy-3-methylglutaryl coenzyme A reductase activity thereby modestly decreasing cholesterol synthesis and concomitantly decreasing LDL cholesterol. The reductase activity in tumor tissues differs from that of liver in being resistant to sterol feedback regulation. Tumor reductase activity retains sensitivity to the post-transcriptional regulation. As a consequence, the isoprenoid-mediated suppression of mevalonate synthesis depletes tumor tissues of two intermediate products, farnesyl pyrophosphate and geranylgeranyl pyrophosphate, which are incorporated post-translationally into growth control-associated proteins. |
| CP-346086: an MTP inhibitor that lowers plasma cholesterol and triglycerides in experimental animals and in humans Chandler, C. E., D. E. Wilder, et al. (2003), J Lipid Res 44(10): 1887-901. Abstract: A microsomal triglyceride transfer protein (MTP) inhibitor, CP-346086, was identified that inhibited both human and rodent MTP activity concentration giving half-maximal inhibition (IC50) 2.0 nM. In Hep-G2 cells, CP-346086 inhibited apolipoprotein B (apoB) and triglyceride secretion (IC50 2.6 nM) without affecting apoA-I secretion or lipid synthesis. When administered orally to rats or mice, CP-346086 lowered plasma triglycerides dose giving 30% triglyceride lowering (ED30) 1.3 mg/kg 2 h after a single dose. Coadministration with Tyloxapol demonstrated that triglyceride lowering was due to inhibition of hepatic and intestinal triglyceride secretion. A 2 week treatment with CP-346086 lowered total, VLDL, and LDL cholesterol and triglycerides dose dependently with 23%, 33%, 75%, and 62% reductions at 10 mg/kg/day. In these animals, MTP inhibition resulted in increased liver and intestinal triglycerides when CP-346086 was administered with food. When dosed away from meals, however, only hepatic triglycerides were increased. When administered as a single oral dose to healthy human volunteers, CP-346086 reduced plasma triglycerides and VLDL cholesterol dose dependently with ED50s of 10 mg and 3 mg, and maximal inhibition (100 mg) of 66% and 87% when measured 4 h after treatment. After a 2 week treatment (30 mg/day), CP-346086 reduced total and LDL cholesterol and triglycerides by 47%, 72%, and 75%, relative to either individual baselines or placebo, with little change in HDL cholesterol. Together, these data support further evaluation of CP-346086 in hyperlipidemia. |
| Crafting a cage for cholesterol Bradley, D. (1994), Science 266(5182): 34. |
| C-reactive protein adds to the predictive value of total and HDL cholesterol in determining risk of first myocardial infarction Ridker, P. M., R. J. Glynn, et al. (1998), Circulation 97(20): 2007-11. Abstract: BACKGROUND: C-reactive protein (CRP) is a sensitive marker of inflammation, and elevated levels have been associated with future risk of myocardial infarction (MI). However, whether measurement of CRP adds to the predictive value of total cholesterol (TC) and HDL cholesterol (HDL-C) in determining risk is uncertain. METHODS AND RESULTS: Among 14916 apparently healthy men participating in the Physicians' Health Study, baseline levels of CRP, TC, and HDL-C were measured among 245 study subjects who subsequently developed a first MI (cases) and among 372 subjects who remained free of cardiovascular disease during an average follow-up period of 9 years (controls). In univariate analyses, high baseline levels of CRP, TC, and TC:HDL-C ratio were each associated with significantly increased risks of future MI (all P values <0.001). In multivariate analyses, models incorporating CRP and lipid parameters provided a significantly better method to predict risk than did models using lipids alone (all likelihood ratio test P values <0.003). For example, relative risks of future MI among those with high levels of both CRP and TC (RR=5.0, P=0.0001) were greater than the product of the individual risks associated with isolated elevations of either CRP (RR=1.5) or TC (RR=2.3). In stratified analyses, baseline CRP level was predictive of risk for those with low as well as high levels of TC and the TC:HDL-C ratio. These findings were virtually identical in analyses limited to nonsmokers and after control for other cardiovascular risk factors. CONCLUSIONS: In prospective data from a large cohort of apparently healthy men, baseline CRP level added to the predictive value of lipid parameters in determining risk of first MI. |
| C-reactive protein binds to the 3beta-OH group of cholesterol in LDL particles Taskinen, S., M. Hyvonen, et al. (2005), Biochem Biophys Res Commun 329(4): 1208-16. Abstract: C-reactive protein (CRP) has been suggested to contribute to the development of atherosclerosis. We previously found binding of CRP to cholesterol in modified low density lipoprotein (LDL) particles. Here, we characterize the interaction between CRP and cholesterol in more detail. When lipids of native LDL were separated by thin-layer chromatography, CRP bound only to cholesterol. When various cholesterol analogues were compared for their ability to bind CRP, we found that any modification of the 3beta-OH group blocked binding of CRP to cholesterol. Similarly, enrichment of LDL with cholesterol but not with its analogues triggered the binding of CRP to LDL. Finally, with the aid of anti-CRP monoclonal antibodies and by molecular modeling, we obtained evidence for involvement of the phosphorylcholine-binding site of CRP in cholesterol binding. Thus, CRP can bind to cholesterol, and the interaction is mediated by the phosphorylcholine-binding site of CRP and the 3beta-hydroxyl group of cholesterol. |
| C-reactive protein in young, apparently healthy men: associations with serum leptin, QTc interval, and high-density lipoprotein-cholesterol Kazumi, T., A. Kawaguchi, et al. (2003), Metabolism 52(9): 1113-6. Abstract: To determine which anthropometric, biochemical, and cardiovascular variables are associated with serum levels of C-reactive protein (CRP) in young, apparently healthy men, a cross-sectional study of 179 male college students aged 18 to 22 years was performed. Multiple regression analysis was used to derive models for serum CRP concentrations in terms of the other variables measured. Although CRP was positively correlated with body mass index (BMI), percent fat mass, and serum leptin, correlations with BMI (r = 0.15, P =.05) and percent body fat (r = 0.16, P =.003) were not as strong as the correlation with leptin (r = 0.28, P =.0002). CRP was also associated with resting heart rate (r = 0.14, P =.05), heart-rate corrected QT (QTc) interval (r = 0.22, P =.003) and several components of the insulin resistance (IR) syndrome. CRP showed a strong and negative association with high-density lipoprotein (HDL)-cholesterol (r = -0.26, P =.0005) and a marginal and positive association with triglyceride (r = 0.14, P =.05). Although CRP was associated with fasting insulin (r = 0.15, P =.04), it was not related to serum adiponectin or IR index estimated using homeostasis model assessment (HOMA). Multiple regression analysis indicated that serum CRP was positively related to serum leptin (P =.003) and QTc interval (P =.01), and negatively correlated with HDL-cholesterol (P =.01, R(2) = 0.15). In young, apparently healthy men, serum leptin but not BMI was independently associated with serum CRP, suggesting that amount of body fat may be the most significant predictor of CRP. Although low-grade inflammation was associated with long QTc interval and low HDL-cholesterol, the mechanism underlying these associations is an important question to be addressed. |
| CREating a SCAP-less liver keeps SREBPs pinned in the ER membrane and prevents increased lipid synthesis in response to low cholesterol and high insulin Osborne, T. F. (2001), Genes Dev 15(15): 1873-8. |
| Creation and activity of COS-1 cells stably expressing the F2 fusion of the human cholesterol side-chain cleavage enzyme system Huang, M. C. and W. L. Miller (2001), Endocrinology 142(6): 2569-76. Abstract: A fusion construct for the human cholesterol side-chain cleavage enzyme system termed F2 (H(2)N-P450scc-adrenodoxin reductase-adrenodoxin-COOH), was stably expressed in nonsteroidogenic COS-1 cells. Multiple clones were obtained and analyzed, identifying the clone COS-F2-130 as the most active in converting 22R-hydroxycholesterol (22R-OH-C) to pregnenolone. The F2 fusion construct was properly transcribed and translated in COS-F2-130 cells, indicating that these cells did not proteolytically cleave the F2 protein. Steroid analyses show that the COS-F2-130 cells do not convert appreciable quantities of pregnenolone to other steroids. Isolated COS-F2-130 mitochondria showed enhanced steroidogenesis when incubated with biosynthetic N-62 StAR protein in vitro. The cells were easily transfectable with StAR expression vectors, showing that COS-F2-130 cells exhibited both StAR-independent and StAR-dependent activity. Transient expression of either full-length or N-62 StAR stimulated steroidogenesis to approximately 45% of the maximal steroidogenic capacity, as indicated by incubation with 22R-OH-C. Single, double, and triple transfections of individual vectors expressing P450scc, adrenodoxin reductase, and adrenodoxin demonstrated that the P450 moiety of the F2 fusion protein could only receive electrons from the covalently linked adrenodoxin moiety, but that free adrenodoxin reductase could foster activity of the fusion enzyme. COS-F2-130 cells provide a useful system for studying steroidogenesis, as these are the only cells described to date that convert cholesterol to pregnenolone but lack downstream enzymes that catalyze other steroidogenic reactions. |
| Creation of double silica nanotubes by using crown-appended cholesterol nanotubes Jung, J. H., S. H. Lee, et al. (2003), Chemistry 9(21): 5307-13. Abstract: New crown-appended cholesterol-based organogelators 1-3, which have one or two cholesterol skeletons as a chiral aggregate-forming site, two amino groups as an acidic proton binding site, and one crown moiety as a cation binding site, were synthesized, and the gelation ability was evaluated in organic solvents. These gelators could gelatinize several organic solvents under 1.0 wt %, indicating that 1-3 act as a versatile gelator of various organic solvents. We observed CD spectra of the acetic acid or propionic acid gels of 1-3 to characterize the aggregation mode in the organogel system. In the CD spectrum of the acetic acid gel 1, the positive sign for the first Cotton effect indicates that the dipole moments of azobenzene chromophores tend to orient into the clockwise direction. On the other hand, propionic acid gels 2 and 3, bearing only one cholesterol, moiety exhibit a negative sign for the first Cotton effect, strongly suggesting that the dipole moments of the azobenzene chromophores orient into the anticlockwise direction. The TEM images of the 1+acetic acid gel resulted in the helical ribbon and tubular structures. Sol-gel polycondensation of tetraethoxysilane (TEOS) was carried out with 1-3 as templates in the gel phase. The silica obtained from the 1+acetic acid gel showed the helical ribbon with 200-1700 nm width and the tubular structure of the silica with constant about 560 nm outer diameter. As far as can be recognized, all the helicity possesses a right-handed helical motif. Since the exciton coupling band of the organogel also shows P (right-handed) helicity, we consider that a microscopic helicity is reflected by a macroscopic helicity. On the other hand, the tubular structure of the silica obtained from the organogels 2 and 3 is somewhat different from that prepared from the organogel 1. The careful examination of SEM and TEM pictures revealed that the tube wall of the silica features a roll-paper-like multilayer structure. Thus, this paper demonstrates successful and rare examples for precise transcription of gel superstructures into inorganic silica materials. |
| Crilvastatin, a new 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, inhibits cholesterol absorption in genetically hypercholesterolemic rats Hajri, T., J. Ferezou, et al. (1995), Eur J Pharmacol 286(2): 131-6. Abstract: Crilvastatin is a new drug from the pyrrolidone family, which acts as a non-competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase. The long-term effects of oral crilvastatin treatment (200 mg per day per kg body weight for 4 and 10 weeks) were investigated on in vivo cholesterogenesis in male adult normocholesterolemic (SW) and genetically hypercholesterolemic (RICO) rats. In both strains of rats, the treatment had no effect on the plasma cholesterol level, but efficiently inhibited cholesterol synthesis in liver and intestine, as shown by the decreased incorporation of exogenous 14Cacetate into hepatic (3.5-fold in SW, 1.7-fold in RICO rats) and intestinal (2.5-fold in SW, 3.3-fold in RICO rats) sterols. In RICO rats in which the dietary cholesterol absorption coefficient was two-fold lower in treated (38%) than in untreated (78%) rats, this drug reduced intestinal cholesterol absorption. As a result, the total plasma cholesterol input (absorption + synthesis), measured by isotope analysis in RICO rats, was markedly lower in treated (11.3 mg per day) than in untreated animals (28.8 mg per day). |
| Cringle conundrums, clotting, cholesterol, and coronaries Luft, F. C. (1996), J Mol Med 74(11): 637-8. |
| Critical analysis of the use of 14C-acetate for measuring in vivo rat cholesterol synthesis Lutton, C., J. Ferezou, et al. (1990), Reprod Nutr Dev 30(1): 71-84. Abstract: The bulk of cholesterol produced by the liver and the gut enters the mobile pool of body cholesterol. This process is called internal secretion in contrast with the fraction of biosynthesized cholesterol directly eliminated in the feces (fecal external secretion). In rats, under various conditions, a linear relationship was found between the rates of internal secretion measured by the isotope equilibrium method (range: 10-60 mg/day) and the sum of sterol radioactivities measured in liver and intestine 70 min after a 14C-acetate pulse. In fact, a better correlation was found between the radioactivities of liver sterols and the values for internal secretion. In this new relationship, the ordinate at the origin corresponds to a minimal internal secretion of about 10 mg/day, which implies an important extrahepatic cholesterol production, probably from the gut. Indeed, in adult male rats, fed a semi-purified sucrose-rich diet, the relative contribution of this organ to the internal secretion was higher than in adult rats fed a commercial diet and higher than in young animals, whatever the circadian period. It can be concluded that some of the discrepancies observed in the literature about the relative participation of the intestine and the liver in the internal secretion of cholesterol are probably due to differences in experimental and nutritional conditions (age and sex of the animals, diet composition, time of the circadian cycle) rather than to the cholesterol precursor used (3H2O or 14C acetate) to assess the activity of cholesterol synthesis. Indeed, a comparative study of 3H2O and 14Cacetate incorporation into sterols of enterocytes indicated the same crypt-villus radioactive gradient, regardless of the intestinal site studied (duodenum, jejunum or ileum) and thus validated the use of 14Cacetate. Other experiments however, showed evidence of some local differences in the cytosolic dilution of labeled acetyl CoA by the endogenous cholesterol precursor in rats under various conditions (control or cholestyramine-enriched diet, parenteral nutrition). After intravenous infusion of 1,213Cacetate, mass fragmentography of free cholesterol isolated from liver and intestine indicated different 13C-labeling patterns of newly synthesized molecules. They indicate that cholesterol is generally synthesized from acetyl CoA with a lower 13C-content in the liver than in the intestine. The local endogenous flow of acetyl CoA used for cholesterol synthesis was about 2-fold higher in the hepatocytes than in the enterocytes. This conclusion was confirmed by the results obtained with several experimental groups exhibiting a large range of both internal secretion of cholesterol and sterol radioactivities in liver and intestine after 14Cacetate injection.(ABSTRACT TRUNCATED AT 400 WORDS) |
| Critical appraisal of revised cholesterol guidelines for the very high-risk patient Rosenson, R. and D. Lloyd-Jones (2005), Expert Rev Cardiovasc Ther 3(1): 173-8. Abstract: A working group from the Adult Treatment Panel III of the national Cholesterol Educational Program issued a revised algorithm for low-density lipoprotein (LDL)-cholesterol lowering in very high-risk cardiovascular disease patients. The rationale of these recommendations was primarily established from pooled analysis of multiple clinical trials of LDL-cholesterol-lowering therapies and limited data from an acute coronary syndrome trial. In the near future, the findings of these large-scale randomized trials designed to test the hypothesis that more aggressive LDL-cholesterol therapy is accompanied by fewer cardiovascular events than less aggressive LDL-cholesterol lowering therapy, will provide the evidence needed to support or refute these new recommendations. In this article, the authors suggest that an LDL-cholesterol level of less than 70 mg/dl is unattainable and not necessary for many high-risk patients. Furthermore, the potential risks associated with high-dose statin agents in certain patients, such as the elderly, may outweigh these putative benefits. |
| Critical points in charged membranes containing cholesterol Radhakrishnan, A. and H. M. McConnell (2002), Proc Natl Acad Sci U S A 99(21): 13391-6. Abstract: Epifluorescence microscopy is used to determine phase diagrams for lipid monolayers containing binary mixtures of cholesterol or dihydrocholesterol and dimyristoylphosphatidylserine, as well as ternary mixtures that also contain ganglioside G(M1). The phase diagrams are unusual in that they show multiple critical points: two upper miscibility critical points and one lower miscibility critical point. These critical points all are associated with the formation of condensed complexes between these lipids and cholesterol (or dihydrocholesterol). The miscibility critical pressures depend on subphase pH and ionic strength. Changes in critical pressures due to changes in subphase composition are closely related to changes in membrane electrostatic pressure and surface ionization. |
| Critical role for cholesterol in Lyn-mediated tyrosine phosphorylation of FcepsilonRI and their association with detergent-resistant membranes Sheets, E. D., D. Holowka, et al. (1999), J Cell Biol 145(4): 877-87. Abstract: Tyrosine phosphorylation of the high affinity immunoglobulin (Ig)E receptor (FcepsilonRI) by the Src family kinase Lyn is the first known biochemical step that occurs during activation of mast cells and basophils after cross-linking of FcepsilonRI by antigen. The hypothesis that specialized regions in the plasma membrane, enriched in sphingolipids and cholesterol, facilitate the coupling of Lyn and FcepsilonRI was tested by investigating functional and structural effects of cholesterol depletion on Lyn/FcepsilonRI interactions. We find that cholesterol depletion with methyl-beta-cyclodextrin substantially reduces stimulated tyrosine phosphorylation of FcepsilonRI and other proteins while enhancing more downstream events that lead to stimulated exocytosis. In parallel to its inhibition of tyrosine phosphorylation, cholesterol depletion disrupts the interactions of aggregated FcepsilonRI and Lyn on intact cells and also disrupts those interactions with detergent-resistant membranes that are isolated by sucrose gradient ultracentrifugation of lysed cells. Importantly, cholesterol repletion restores receptor phosphorylation together with the structural interactions. These results provide strong evidence that membrane structure, maintained by cholesterol, plays a critical role in the initiation of FcepsilonRI signaling. |
| Critical role of diacylglycerol- and phospholipid-regulated protein kinase C epsilon in induction of low-density lipoprotein receptor transcription in response to depletion of cholesterol Mehta, K. D., A. Radominska-Pandya, et al. (2002), Mol Cell Biol 22(11): 3783-93. Abstract: Induction of low-density lipoprotein (LDL) receptor transcription in response to depletion of cellular sterols in animal cells is well established. The intracellular signal or signals involved in regulating this process, however, remain unknown. Using a specific inhibitor of protein kinase C (PKC), calphostin C, we show the requirement of this kinase in the induction process in human hepatoma HepG2 cells. Overexpression of PKC epsilon, but not PKC alpha, -gamma, -delta, or -zeta was found to dramatically induce (approximately 18-fold) LDL receptor promoter activity. Interestingly, PKC epsilon-mediated induction was found to be sterol resistant. To further establish that PKC epsilon is involved in the sterol regulation of LDL receptor gene transcription, endogenous PKC epsilon was specifically inhibited by transfection with antisense PKC epsilon phosphorothionate oligonucleotides. Antisense treatment decreased endogenous PKC epsilon protein levels and completely blocked induction of LDL receptor transcription following sterol depletion. PKC epsilon-induced LDL receptor transcription is independent of the extracellular signal-regulated kinase 1 and 2 (p42/44(MAPK)) cascade, because the MEK-1/2 inhibitor, PD98059 did not inhibit, even though it blocked p42/44(MAPK) activation. Finally, photoaffinity labeling studies showed an isoform-specific interaction between PKC epsilon and sterols, suggesting that sterols may directly modulate its function by hampering binding of activators. This was confirmed by PKC activity assays. Altogether, these results define a novel signaling pathway leading to induction of LDL receptor transcription following sterol depletion, and a model is proposed to account for a new function for PKC epsilon as part of a sterol-sensitive signal transduction pathway in hepatic cells. |
| Cross sectional survey of effectiveness of lipid lowering drugs in reducing serum cholesterol concentration in patients in 17 general practices Hippisley-Cox, J., R. Cater, et al. (2003), Bmj 326(7391): 689. Abstract: OBJECTIVE: To compare the effectiveness of lipid lowering drugs in lowering serum cholesterol concentrations. DESIGN: Cross sectional study. SETTING: 17 practices within 17 primary care groups in Trent region, United Kingdom. PARTICIPANTS: Patients aged 35 years or over taking lipid lowering drugs and with at least two serum cholesterol concentrations recorded on computer. MAIN OUTCOME MEASURES: Proportion of patients achieving serum cholesterol concentration of < or =5 mmol/l and mean percentage reduction in serum cholesterol concentration. RESULTS: 1353 of 2469 (54.8%) patients receiving lipid lowering treatment had a last recorded serum cholesterol concentration of < or =5 mmol/l. Significantly more patients taking statins achieved the target value for serum cholesterol (5 mmol/l) than those taking fibrates (1307 (57%) v 46 (26%); P<0.0001). Atorvastatin and simvastatin were the most effective drugs in achieving the target. Significant differences were found between lipid lowering drugs for the pretreatment serum cholesterol concentration, the most recent cholesterol concentration, and the associated percentage reduction. Atorvastatin and simvastatin achieved the greatest percentage reduction in serum cholesterol concentrations (30.1%, 95% confidence interval 28.8% to 31.4%, and 28.0%, 26.7% to 29.3%, respectively). Although the mean serum cholesterol concentrations in this unselected population tended to be higher than those in clinical trials, the percentage reduction was consistent with the trials. CONCLUSION: The ability of individual statins to lower serum cholesterol concentration varied, with atorvastatin and simvastatin being the most effective. The percentage reductions agreed with those of randomised controlled trials indicating likely benefits in unselected patients in primary care. As the initial serum cholesterol concentrations were higher than those in randomised controlled trials, target serum cholesterol values of < or =5 mmol/l may be unrealistic even for patients taking the most efficacious drugs. Also, the higher initial levels could mean that the absolute reduction in cardiovascular risk in primary care patients is greater than thought. |
| Cross-inhibition of SR-BI- and ABCA1-mediated cholesterol transport by the small molecules BLT-4 and glyburide Nieland, T. J., A. Chroni, et al. (2004), J Lipid Res 45(7): 1256-65. Abstract: Scavenger receptor class B type I (SR-BI) and ABCA1 are structurally dissimilar cell surface proteins that play key roles in HDL metabolism. SR-BI is a receptor that binds HDL with high affinity and mediates both the selective lipid uptake of cholesteryl esters from lipid-rich HDL to cells and the efflux of unesterified cholesterol from cells to HDL. ABCA1 mediates the efflux of unesterified cholesterol and phospholipids from cells to lipid-poor apolipoprotein A-I (apoA-I). The activities of ABCA1 and other ATP binding cassette superfamily members are inhibited by the drug glyburide, and SR-BI-mediated lipid transport is blocked by small molecule inhibitors called BLTs. Here, we show that one BLT, 1-(2-methoxy-phenyl)-3-naphthalen-2-yl-urea (BLT-4), blocked ABCA1-mediated cholesterol efflux to lipid-poor apoA-I at a potency similar to that for its inhibition of SR-BI (IC(50) approximately 55-60 microM). Reciprocally, glyburide blocked SR-BI-mediated selective lipid uptake and efflux at a potency similar to that for its inhibition of ABCA1 (IC(50) approximately 275-300 microM). As is the case with BLTs, glyburide increased the apparent affinity of HDL binding to SR-BI. The reciprocal inhibition of SR-BI and ABCA1 by BLT-4 and glyburide raises the possibility that these proteins may share similar or common steps in their mechanisms of lipid transport. |