| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
| First Page | Previous Page | Next Page | Last Page |
| Prolonged inhibition of cholesterol synthesis by atorvastatin inhibits apo B-100 and triglyceride secretion from HepG2 cells Funatsu, T., K. Suzuki, et al. (2001), Atherosclerosis 157(1): 107-15. Abstract: Atorvastatin is a new HMG-CoA reductase inhibitor that strongly lowers plasma cholesterol and triglyceride (TG) levels in humans and animals. Since previous data indicated that atorvastatin has prolonged inhibition of hepatic cholesterol synthesis, we tested whether this longer duration of inhibitory effect on cholesterol synthesis decreased hepatic lipoprotein secretion in vitro. We used the HepG2 hepatoma cell line to: (1) determine the time required until levels of secreted apo B-100 and TG declined significantly, (2) examine the relation to the mass of cellular cholesteryl ester (CE) and (3) test microsomal triglyceride transfer protein (MTP) activity which leads to decreased apo B-100 production. Although atorvastatin significantly inhibited cholesterol synthesis in HepG2 cells regardless of treatment duration (1, 14 or 24 h), it did not inhibit TG synthesis. Apo B-100 and TG secretion were unchanged after 1-h atorvastatin treatment, but declined significantly after 24-h treatment. Atorvastatin treatment also reduced cellular CE mass, exhibiting both time- and dose-dependency. Mevalonolactone, a product of HMG-CoA reductase, attenuated the inhibitory effects of atorvastatin. Atorvastatin strongly reduced mRNA levels of MTP, whereas it did not inhibit MTP activity as measured by TG transfer assay between liposomes. Simvastatin also induced treatment- and time-dependent reductions in apo B-100, whereas the MTP inhibitor BMS-201038 exhibited no time dependency, instead inhibiting this variable even on 1-h treatment. These results indicate that reduced apo B-100 secretion caused by atorvastatin is a secondary result owing to decreased lipid availability, and that atorvastatin's efficacy depends on the duration of cholesterol synthesis inhibition in the liver. |
| Prolonged inhibition of cholesterol synthesis explains the efficacy of atorvastatin Naoumova, R. P., S. Dunn, et al. (1997), J Lipid Res 38(7): 1496-500. Abstract: HMG-CoA reductase inhibitors or statins are effective in both the primary and secondary prevention of coronary heart disease, the extent of benefit being proportional to the reduction in low density lipoprotein (LDL) cholesterol achieved. Atorvastatin, a newly licensed compound, reportedly lowers LDL with greater efficacy than other statins. The mechanism of this action was, therefore, explored in twenty patients with refractory familial hypercholesterolemia who received in a single-blind sequence simvastatin 40 mg/day, placebo and atorvastatin 10 mg/day each for 4 weeks. At the end of the placebo period the effects of single 40-mg doses of simvastatin and atorvastatin on plasma levels and urinary excretion of mevalonic acid, indices of HMG-CoA reductase activity, were compared. Administration of atorvastatin 10 mg daily for 1 month lowered LDL cholesterol by 32.5%, compared with placebo (P = 0.0001), which was 4.5% less than the decrease after simvastatin 40 mg daily (P = 0.33). The area under the plasma curve and urinary mevalonic acid/ creatinine ratio were both significantly less during the 24 h after a single dose of atorvastatin 40 mg than after a single dose of simvastatin 40 mg (P < 0.01). These findings suggest that the greater efficacy of atorvastatin compared with simvastatin is due to more prolonged inhibition of HMG-CoA reductase, presumably reflecting longer residence of atorvastatin or its active metabolites in the liver. |
| Prolonged stimulation of the adrenals by corticotropin suppresses hepatic low-density lipoprotein and high-density lipoprotein receptors and increases plasma cholesterol Galman, C., B. Angelin, et al. (2002), Endocrinology 143(5): 1809-16. Abstract: Pituitary ACTH has been shown to strongly stimulate adrenal receptors for low-density lipoprotein (LDL) and high-density lipoprotein (HDL) scavenger receptor class B type 1(SR-BI) to provide precursor cholesterol for glucocorticoid synthesis. The present study aimed to determine the effects of ACTH on hepatic cholesterol metabolism and plasma lipoproteins. Treatment of Sprague Dawley rats or normal C57BL/6J mice with ACTH for 3.5 d reduced hepatic SR-BI and LDL receptors. Simultaneously, cholesterol in plasma LDL and HDL was increased. None of these effects could be reproduced using glucocorticoids instead of ACTH, and they were abolished in adrenalectomized rats, indicating an obligate role of the adrenals for the effects of ACTH observed in the liver. When ACTH was given to LDL receptor-deficient mice, plasma LDL did not increase and the increase in HDL cholesterol remained, as did the suppression of hepatic SR-BI. Our data show that prolonged ACTH treatment suppresses hepatic SR-BI and LDL receptors in vivo in rodents, resulting in elevated plasma HDL and LDL. The adrenals are obligate for these effects, suggesting that ACTH releases some factor(s) that suppresses hepatic LDL and SR-BI receptors. Hypothetically, this novel mechanism would further promote channeling of cholesterol to the adrenals in situations of prolonged stress. |
| Prominin: a story of cholesterol, plasma membrane protrusions and human pathology Corbeil, D., K. Roper, et al. (2001), Traffic 2(2): 82-91. Abstract: Prominin is the first identified member of a novel family of polytopic membrane proteins conserved throughout the animal kingdom. It has an unusual membrane topology, containing five transmembrane domains and two large glycosylated extracellular loops. In mammals, prominin is expressed in various embryonic and adult epithelial cells, as well as in nonepithelial cells, such as hematopoietic stem cells. At the subcellular level, prominin is selectively localized in microvilli and other plasma membrane protrusions, irrespective of cell type. At the molecular level, prominin specifically interacts with membrane cholesterol and is a marker of a novel type of cholesterol-based lipid 'raft'. A frameshift mutation in the human prominin gene, which results in a truncated protein that is no longer transported to the cell surface, is associated with retinal degeneration. Given that prominin is concentrated in the plasma membrane evaginations at the base of the outer segment of rod photoreceptor cells, which are essential precursor structures in the biogenesis of photoreceptive disks, it is proposed that prominin has a role in the generation of plasma membrane protrusions, their lipid composition and organization and their membrane-to-membrane interactions. |
| Promising therapies for cholesterol reduction Brown, W. V. (2002), Manag Care 11(9 Suppl): 10-4. |
| Promoting adherence to low-fat, low-cholesterol diets: review and recommendations McCann, B. S., B. M. Retzlaff, et al. (1990), J Am Diet Assoc 90(10): 1408-14, 1017. Abstract: Evidence that lowering blood cholesterol levels reduces risk of coronary heart disease has prompted widespread recommendations that hyperlipidemic individuals undergo dietary therapy. However, the extent to which people can adopt and maintain diets to lower lipids is unclear. In our article, we review what is currently known regarding adherence to low-fat diets and present an approach to dietary counseling for lowering cholesterol that incorporates elements of behavioral self-management and social learning theory. We discuss specific recommendations for counseling hyperlipidemic patients based on the Dietary Alternatives Study. Recommendations include providing patients with an adequate knowledge base to make dietary changes, using goal setting and self-monitoring to help patients initiate dietary changes, enlisting support from the patient's family, and enhancing self-efficacy to promote long-term dietary maintenance. |
| Promoting effects of both dietary cholesterol and cholestyramine on pancreatic carcinogenesis initiated by N-nitrosobis(2-oxopropyl)amine in Syrian golden hamsters Ogawa, T., T. Makino, et al. (1992), Carcinogenesis 13(11): 2047-52. Abstract: The effects of dietary cholesterol and cholestyramine on pancreatic carcinogenesis initiated with N-nitrosobis(2-oxopropyl)amine (BOP) were investigated in 120 female Syrian golden hamsters. BOP (70 mg/kg body weight) was injected s.c. once at the beginning of the experiment. Starting 2 weeks later, the animals were then maintained on basal diet or diets containing either 0.5% cholesterol or 1% cholestyramine for a further 16 weeks. All surviving hamsters were killed at week 18, and the pancreas tissues examined histologically. The incidences of pancreatic carcinomas in hamsters fed cholesterol and the cholestyramine supplement were 40.0 and 30.0% respectively; in both cases significantly higher than the 6.9% incidence in the basal diet group. Cholesterol contents of the serum, pancreas and liver were significantly increased by cholesterol feeding and significantly decreased by the cholestyramine diet. The cholesterol diet also significantly increased pancreatic protein and DNA contents, and the concentration of total bile acids and the level of lithocholic acid in gallbladder bile. The cholestyramine diet significantly increased total pancreatic DNA and protein contents, and pancreatic weight. The results thus indicated that both dietary cholesterol and cholestyramine can enhance BOP-initiated pancreatic carcinogenesis in hamsters. |
| Promoting export of macrophage cholesterol: the physiological role of a major acute-phase protein, serum amyloid A 2.1 Tam, S. P., A. Flexman, et al. (2002), J Lipid Res 43(9): 1410-20. Abstract: We show that murine macrophages that have ingested cell membranes as a source of cholesterol exhibit a marked increase in acyl-CoA:cholesterol acyl transferase (ACAT) activity. Exposure of these macrophages to acute-phase high-density lipoprotein (HDL) results in a marked reduction of ACAT and enhancement of cholesteryl ester hydrolase (CEH) activities, phenomena not seen with native HDL. These complementary but opposite effects of acute-phase HDL on the two enzyme systems that regulate the balance between esterified (storage) cholesterol and unesterified (transportable) cholesterol are shown to reside with serum amyloid A (SAA) 2.1, an acute-phase apolipoprotein of HDL whose plasma concentration increases 500- to 1,000-fold within 24 h of acute tissue injury. Mild trypsin treatment of acute-phase HDL almost completely abolishes the apolipoprotein-mediated effects on the cholesteryl ester cycle in cholesterol-laden macrophages. The physiological effect of SAA2.1 on macrophage cholesterol is to shift it into a transportable state enhancing its rate of export, which we confirm in tissue culture and in vivo. The export process is shown to be coupled to the ATP binding cassette transport system. Our findings integrate previous isolated observations about SAA into the sphere of cholesterol transport, establish a function for a major acute-phase protein, and offer a novel approach to mobilizing macrophage cholesterol at sites of atherogenesis. |
| Promotion of carcinogenesis and oxidative stress by dietary cholesterol in rat prostate Homma, Y., Y. Kondo, et al. (2004), Carcinogenesis 25(6): 1011-4. Abstract: The association between prostate cancer risk and dietary fat consumption is well documented and explained partly by accelerated lipid peroxidation. We explored the possible effects of high dietary cholesterol on carcinogenesis and oxidative stress in the prostate of ACI/Seg rats. The rats develop prostate cancer spontaneously late in the life, providing an appropriate model to explore prolonged dietary conditions. Two groups of 20-week-old male rats, 28 each, were fed either a basal diet or a basal diet supplemented with 1% cholesterol (high cholesterol diet), and killed at 100 weeks of age. Rats on the high cholesterol diet developed adenocarcinoma in the ventral prostate more frequently (26 versus 4%, P = 0.023). In the repeat study, 26 rats each were treated similarly and killed at 80 weeks for histology and oxidative stress assay. Oxidative stress was assessed by measuring the plasma and intra-prostatic levels of vitamin E, vitamin C, uric acid and the oxidized and reduced forms of coenzyme Q(9). The relative amount of oxidized form of coenzyme Q(9) is a sensitive marker of oxidative stress. Rats on the high cholesterol diet demonstrated a higher incidence of atypical prostatic hyperplasia (24 versus 4%, P = 0.049). Also, the prostate showed a 2-fold increase (203% of the control) in the relative amounts of the oxidized form of coenzyme Q(9) and reciprocal reduction of vitamin C (9.5% of the control) and uric acid (46% of the control) levels (P < 0.01), with a minimal change in vitamin E. The plasma levels of these compounds were not affected by dietary conditions. These results indicated that long-term feeding of a 1% cholesterol diet promoted carcinogenesis and tissue oxidative stress in rat prostate. The role of dietary fat and oxidative stress in prostate carcinogenesis needs further investigation. |
| Promotion of colon carcinogenesis through increasing lipid peroxidation induced in rats by a high cholesterol diet Tseng, T. H., J. D. Hsu, et al. (1996), Cancer Lett 100(1-2): 81-7. Abstract: To examine the influence of hypercholesteremia on 1,2-dimethylhydrazine (DMH)-induced rat colon cancer, Sprague-Dawley rats received dietary cholesterol (CH, 0-2%) and cholic acid (CA, 0.25%) with or without DMH (20 mg/kg, s.c. injection) for 18 weeks. The rats receiving dietary cholesterol and cholic acid all significantly increased total serum cholesterol and lipids but only a high cholesterol diet (2% CH plus 0.25% CA) decreased the activity of glutathione peroxidase (GSH-Px) and increased the formation of peroxides in the colon (P < 0.01). The rats that received the combination of DMH and high cholesterol diet enhanced these effects. At the end of the experiment, the diet group administered DMH and high cholesterol (2% CH plus 0.25% CA) developed colon adenoma at 50% of incidence in pathological examination, but no colon adenoma formed in the rats treated with high cholesterol alone. It is supposed that a non-carcinogenic agent like cholesterol may potentiate the carcinogenicity of DMH in rats via an increase of lipid peroxidation and decrease in the activity of peroxidase in the target organ. |
| Promotion of tau phosphorylation by MAP kinase Erk1/2 is accompanied by reduced cholesterol level in detergent-insoluble membrane fraction in Niemann-Pick C1-deficient cells Sawamura, N., J. S. Gong, et al. (2003), J Neurochem 84(5): 1086-96. Abstract: Niemann-Pick type C (NPC) disease is a cholesterol-storage disease accompanied by neurodegeneration with the formation of neurofibrillary tangles, the major component of which is the hyperphosphorylated tau. Here, we examined the mechanism underlying hyperphosphorylation of tau using mutant Chinese hamster ovary (CHO) cell line defective in NPC1 (CT43) as a tool. Immunoblot analysis revealed that tau was hyperphosphorylated at multiple sites in CT43 cells, but not in their parental cells (25RA) or the wild-type CHO cells. In CT43 cells, mitogen-activated protein (MAP) kinase Erk1/2 was activated and the specific MAPK inhibitor, PD98059, attenuated the hyperphosphorylation of tau. The amount of protein phosphatase 2A not bound to microtubules was decreased in CT43 cells. CT43 cells but not 25RA cells were amphotericin B-resistant, indicating that cholesterol level in the plasma membrane of CT43 is decreased. In addition, the level of cholesterol in the detergent-insoluble, low-density membrane (LDM) fraction of CT43 cells was markedly reduced compared with the other two types of CHO cells. As LDM domain plays critical role in signaling pathways, these results suggest that the reduced cholesterol level in LDM domain due to the lack of NPC1 may activate MAPK, which subsequently promotes tau phosphorylation in NPC1-deficient cells. |
| Pronuclear and antinuclear factors in the pathogenesis of cholesterol cholelithiasis Marecek, Z., G. Entlicher, et al. (2000), Cas Lek Cesk 139 Suppl 1: 22-6. Abstract: Contrary to hitherto published results, the authors provided evidence of significant pronucleation activity in the protein fraction which is not linked to concanavaline A. Delipidation or proteolysis markedly reduce the pronucleation activity of this fraction. Albumin was identified as the main protein in this fraction. The lipid-protein complex formed by albumin and lipids had a high pronucleation and crystallization activity in relation to cholesterol. Calcium ions increased the crystalization activity. Complexes formed by proteins and lipids can be vectors of the main pronucleation activity in bile. In investigations of the main cholesterol fraction the authors provided evidence that only part of so-called pronucleation proteins is linked to vesicles--i.e. IgM, IgA and biliary glycoprotein BGP I and II. The authors assume that only proteins firmly linked to vesicles can participate in the process of cholesterol crystallization. Biliary glycoprotein BGP I and II was present in vesicles and when added into a model bile it presented a high pronucleation activity. Biliary glycoprotein is a new hitherto not identified pronucleation protein in bile. |
| Properties of low-fat, low-cholesterol egg yolk prepared by supercritical CO2 extraction Bringe, N. A. (1997), Adv Exp Med Biol 415: 161-81. Abstract: A dry egg yolk ingredient called Eggcellent has 74% less fat and 90% less cholesterol than liquid egg yolks, when reconstituted on an equal protein basis. The phospholipids and proteins are retained, enabling the ingredient to have the taste and texturizing properties of fresh egg yolk. Using the new yolk, it is possible to significantly improve the acceptability of low-fat, low-cholesterol bakery products, scrambled eggs and mayonnaise dressings without losing nutritional claims. The structures and functional properties of egg yolk components and the conditions required to optimize their benefits in foods are reviewed. The lipoproteins of low-fat, low-cholesterol yolk have valuable properties as flavorants, texturizers, foaming agents, emulsifiers, antioxidants, colorants, and nutraceuticals. |
| Properties of mixtures of cholesterol with phosphatidylcholine or with phosphatidylserine studied by (13)C magic angle spinning nuclear magnetic resonance Epand, R. M., A. D. Bain, et al. (2002), Biophys J 83(4): 2053-63. Abstract: The behavior of cholesterol is different in mixtures with phosphatidylcholine as compared with phosphatidylserine. In (13)C cross polarization/magic angle spinning nuclear magnetic resonance spectra, resonance peaks of the vinylic carbons of cholesterol are a doublet in samples containing 0.3 or 0.5 mol fraction cholesterol with 1-palmitoyl-2-oleoyl phosphatidylserine (POPS) or in cholesterol monohydrate crystals, but a singlet with mixtures of cholesterol and 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC). At these molar fractions of cholesterol with POPS, resonances of the C-18 of cholesterol appear at the same chemical shifts as in pure cholesterol monohydrate crystals. These resonances do not appear in samples of POPS with 0.2 mol fraction cholesterol or with POPC up to 0.5 mol fraction cholesterol. In addition, there is another resonance from the cholesterol C18 that appears in all of the mixtures of phospholipid and cholesterol but not in pure cholesterol monohydrate crystals. Using direct polarization, the fraction of cholesterol present as crystallites in POPS with 0.5 mol fraction cholesterol is found to be 80%, whereas with the same mol fraction of cholesterol and POPC none of the cholesterol is crystalline. After many hours of incubation, cholesterol monohydrate crystals in POPS undergo a change that results in an increase in the intensity of certain resonances of cholesterol monohydrate in (13)C cross polarization/magic angle spinning nuclear magnetic resonance, indicating a rigidification of the C and D rings of cholesterol but not other regions of the molecule. |
| Properties of phosphatidylethanolamine-containing phospholipid-apolipoprotein complexes modified by lecithin-cholesterol acyltransferase Bonomo, E. A., J. E. Matsuura, et al. (1991), Biochim Biophys Acta 1082(3): 265-74. Abstract: The effect of the inclusion of phosphatidylethanolamine (PE), a phospholipid with unusual packing properties, on the substrate properties of protein-lipid complexes toward lecithin-cholesterol acyltransferase (LCAT) has been studied. Recombinant particles of apolipoprotein A-I with dimyristoylphosphatidylcholine (DMPC), dilauroylphosphatidylethanolamine (DLPE) and cholesterol were prepared at a molar ratio of 1:140:14 (A-I/DMPC/cholesterol) or 1:70:70:14 (A-I/DMPC/DLPE/cholesterol); the efficiency of cholesterol incorporation into complexes containing phosphatidylethanolamine was found to be very pH-dependent, with enhanced cholesterol incorporation at elevated pH values. By incubating the complexes with either purified human LCAT or the d greater than 1.21 g/ml fraction of rat serum as a source of LCAT activity, it was found that a high degree of cholesterol esterification could be achieved with either complex; however, the DLPE-containing complex possessed a much smaller Stokes' diameter than the DMPC-only particle despite compositional similarities between these complexes. With respect to particle diameter the DLPE-containing particles behaved more like complexes prepared with egg yolk lecithin than did complexes prepared with DMPC alone. When human LDL was added to the incubations to provide a source of additional cholesterol, the products were markedly different. Concomitant with an increased cholesteryl ester core was an increase in the protein stoichiometry in both types of particles, from 2 to 3 or 4 apo A-I per particle. The proportion of DLPE to DMPC in the products was reduced from 1:1 to 0.3:1, reflecting a preferential hydrolysis of PE by LCAT, and the Stokes' diameters of the DMPC-only and the DLPE-containing complexes were closely similar. We conclude that the presence of elevated proportions of certain phospholipid species may significantly alter both the physical properties of the particles and their substrate properties with regard to reactions with enzymes of lipid metabolism. |
| Properties of polyunsaturated phosphatidylcholine membranes in the presence and absence of cholesterol Epand, R. M., R. F. Epand, et al. (2004), Magn Reson Chem 42(2): 139-47. Abstract: Mixtures of cholesterol with phosphatidylcholine species containing the polyunsaturated acyl chains arachidonoyl or docosahexaenoyl were studied by (13)C magic angle spinning (MAS) NMR using both cross-polarization and direct polarization, by (31)P NMR and by differential scanning calorimetry. Several unique features of these systems were observed. The separation of cholesterol in crystalline form occurred at much lower molar fractions than with other forms of phosphatidylcholine. The crystals that were formed were sensitive to the history of the sample. At cholesterol molar fractions below 0.5, they dissolved into the membrane by sequential heating and cooling scans. With higher molar fractions of cholesterol, larger amounts of anhydrous crystals were formed after the first heating. This was accompanied by the formation of non-lamellar phases. The cholesterol crystals that were formed generally were not observed by direct polarization (13)C MAS NMR, even with delay times of 100 s. This suggests that the cholesterol crystals are in a more rigid state in mixtures with these lipids. This is in contrast with the terminal methyl group of the acyl chains that is too mobile to allow cross-polarization using 1 ms contact times. |
| Properties of triglyceride-rich and cholesterol-rich lipoproteins in the remnant-like particle fraction of human blood plasma Campos, E., L. Kotite, et al. (2002), J Lipid Res 43(3): 365-74. Abstract: An immunoassay procedure that quantifies remnant-like particle (RLP) cholesterol in human blood plasma has shown considerable promise as a clinically applicable risk marker for atherosclerotic disease. The lipoproteins included in this assay include not only certain TG-rich lipoproteins all particles containing apolipoprotein B-48 (apoB-48) and a fraction of those containing apoB-100 but also a very small proportion of plasma cholesterol-rich lipoproteins. The TG-rich lipoprotein component of RLP has been partially characterized, but relatively little is known about the component cholesterol-rich lipoproteins. We have further characterized the properties of the TG-rich component that is included in RLP in which about 25% of the particles contain apoB-48 and the remainder apoB-100. We show that the cholesterol-rich component is comprised mainly of beta-migrating LDLs that contain predominantly apoB-100. ApoE found in the LDL fraction of RLP resides on pre-beta lipoproteins that lack apoA-I as well as apoB. The TG-rich component of RLP is responsible for increased RLP-cholesterol concentrations associated with hypertriglyceridemia. By contrast, the cholesterol-rich component is a major contributor to plasma RLP-cholesterol in individuals with low plasma TG. Our results suggest that particle heterogeneity in the RLP fraction is likely to affect the ability of RLP-cholesterol concentration to predict atherosclerotic risk. RLP-cholesterol concentrations in individuals with low plasma TG may not have the same clinical significance as they do in those with hypertriglyceridemia. |
| Proportion of alcohols of cholesterol, glycerol and double bonds of fatty acids in blood serum and lipoproteins. Diagnostic significance of hypercholesterolemia Titov, V. N., D. M. Lisitsyn, et al. (2002), Klin Lab Diagn(12): 3-8. Abstract: A new method in quantitative determination of double bonds (DB) in the pool of fatty acids (FA) has been worked out by ozone titration after extraction of lipids according to Folch. A correlation was observed among DB content, the level of cholesterol alcohol (CS, r = +0.612; p < 0.001) and the level of glycerol (GL) alcohol (r = +0.392; p < 0.01). The grown-ups with ischemic heart disease and children have a constant ratio (5.05 +/- 0.18) DB:CS ratio. |
| Prospective association between low and high total and low-density lipoprotein cholesterol and coronary heart disease in elderly men Curb, J. D., R. D. Abbott, et al. (2004), J Am Geriatr Soc 52(12): 1975-80. Abstract: OBJECTIVES: To examine the relationship between total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) and the incidence of coronary heart disease (CHD) in elderly men. DESIGN: Prospective. SETTING: Population based. PARTICIPANTS: A sample of 2,424, Japanese-American men aged 71 to 93 was used. MEASUREMENTS: Six years of data on incident fatal plus nonfatal CHD were examined. RESULTS: Analysis revealed a significant U-shaped relationship between age-adjusted CHD rates and both TC and LDL-C. The ranges of TC and LDL-C with the lowest risk of CHD were 200 to 219 mg/dL and 120 to 139 mg/dL, respectively. As cholesterol concentrations declined and increased beyond these ranges, the risk of CHD increased. These U-shaped relationships remained significant after adjusting for age and other risk factors. CONCLUSION: The U-shaped associations between TC and LDL-C and CHD imply a complex relationship between lipids and CHD in late life. The results indicate that elevated lipid levels should continue to be treated in healthy elderly individuals, as they are in those who are younger, although pharmacologically lowering lipids to excessively low levels in the elderly may warrant further study, as does the contribution of subclinical frailty to the relationship of lipids to CHD risk. |
| Prospective meta-analysis of cholesterol-lowering studies: the Prospective Pravastatin Pooling (PPP) Project and the Cholesterol Treatment Trialists (CTT) Collaboration Simes, R. J. (1995), Am J Cardiol 76(9): 122C-126C. Abstract: Meta-analyses of randomized trials evaluating cholesterol-lowering therapy have demonstrated clear reductions in coronary events and coronary mortality. However, the treatment impact on total mortality has been less certain. With the variable selection of trials and treatment questions, results of meta-analyses have sometimes given conflicting conclusions regarding the magnitude of treatment effects and the populations to whom benefits might accrue. Prospective meta-analysis can avoid these problems by clearly specifying the research questions, eligible studies, analysis plans, and outcome definitions in advance of trial results publication. This approach has been adopted in 2 major prospective meta-analyses of cholesterol-lowering treatments: the Prospective Pravastatin Pooling (PPP) project and the Cholesterol Treatment Trialists (CTT) collaboration. The PPP project is a prospectively planned combined analysis of 3 large-scale pravastatin trials comparing pravastatin against placebo over a minimum 5-year period. The analysis will contain data for > 19,500 patients and should have the power to examine the effects of treatment on total mortality, coronary mortality, and incidence of cancers as well as the ability to look at total coronary events in important subgroups underrepresented in previous trials. The CTT collaboration is a planned prospective meta-analysis of 12 major ongoing or planned randomized trials evaluating therapy with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, a fibrate, or dietary modification. The trials were prospectively registered and the CTT protocols became final in November 1994. By the year 2000, the CTT collaboration is projected to have information on about 65,000 patients.(ABSTRACT TRUNCATED AT 250 WORDS) |