| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| New developments in the prevention of atherosclerosis in patients with low high-density lipoprotein cholesterol Brousseau, M. E. and E. J. Schaefer (2001), Curr Atheroscler Rep 3(5): 365-72. Abstract: Epidemiologic studies have established that a low concentration of plasma high-density lipoprotein (HDL) cholesterol is an independent risk factor for coronary heart disease (CHD). In the United States, a low HDL cholesterol concentration is the most prevalent lipid abnormality observed in men with known CHD. Despite this fact, surprisingly few clinical trials have been designed to investigate the effects of pharmacologic agents on HDL cholesterol-raising and CHD risk in large populations, perhaps due, in part, to the lack of available drugs having significant HDL cholesterol-raising potential. The purpose of this report is to review recent primary and secondary prevention trials that have explored the relationships between drug therapy, HDL cholesterol concentration, and CHD events or progression. Emphasis will be placed on the results of the Veterans Affairs High-Density Lipoprotein Trial, a study that was specifically designed to test the hypothesis that HDL cholesterol-raising with gemfibrozil would reduce CHD morbidity and mortality in patients with CHD whose primary lipid abnormality was a low level of HDL cholesterol. |
| New developments in the treatment of low high-density lipoprotein cholesterol Miller, M. (1999), Curr Atheroscler Rep 1(1): 24-30. Abstract: Reduced levels of high-density lipoprotein (HDL) cholesterol represent an important risk factor for the development and progression of coronary artery disease. In recent years, clinical outcome studies have verified that statin therapy may reduce the risk of initial or recurrent cardiovascular events in subjects with elevated or "normal" cholesterol levels. Subgroup analysis has also revealed that patients with low HDL benefit from this therapy. Two recently presented outcome trials using fibrate therapy also demonstrated a potential role for these medications in subjects with low HDL. The use of various HDL raising agents, singly or in combination on arteriographic progression and their potential mechanisms of action are reviewed. The latter may be an important consideration in the treatment of high-risk patients with low HDL. |
| New features of the National Cholesterol Education Program Adult Treatment Panel III lipid-lowering guidelines Brewer, H. B., Jr. (2003), Clin Cardiol 26(4 Suppl 3): III19-24. Abstract: The National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) guidelines for lipid-lowering therapy to reduce coronary heart disease (CHD) risk contain a number of features that distinguish them from the previous ATP guidelines. These new features include modifications in lipid/lipoprotein levels considered optimal, abnormal, or reflective of risk; increased focus on primary prevention through use of Framingham risk scoring to define risk in persons with multiple lipid/nonlipid risk factors; and increased focus on the association of the metabolic syndrome with CHD risk. The introduction of the category of CHD risk equivalents-including persons with atherosclerotic disease, diabetes, or 10-year CHD risk > 20% based on Framingham scoring-results in an increase over previous guidelines in the proportion of patients categorized as being at high risk and therefore eligible for more intensive low-density lipoprotein cholesterol (LDL-C)-lowering therapy. Use of the new secondary therapeutic target of non-high-density lipoprotein cholesterol should improve management of lipid risk factors in patients who have elevated triglyceride levels after LDL-C goals have been met. These new features of the NCEP ATP III guidelines should improve identification and treatment of patients with dyslipidemias associated with CHD risk. |
| New fluorescent cholesterol analogs as membrane probes Grechishnikova, I. V., F. Bergstrom, et al. (1999), Biochim Biophys Acta 1420(1-2): 189-202. Abstract: New fluorescent cholesterol analogs, (22E, 20R)-3beta-hydroxy-23-(9-anthryl)-24-norchola-5,22-die ne (R-AV-Ch), and the 20S-isomer (S-AV-Ch) were synthesized, their spectral and membrane properties were characterized. The probes bear a 9-anthrylvinyl (AV) group instead of C22-C27 segment of the cholesterol alkyl chain. Computer simulations show that both of the probes have bulkier tail regions than cholesterol and predict some perturbation in the packing of membranes, particularly for R-AV-Ch. In monolayer experiments, the force-area behavior of the probes was compared with that of cholesterol, pure and in mixtures with palmitoyloleoyl phosphatidylcholine (POPC) and N-stearoyl sphingomyelin (SSM). The results show that pure R-AV-Ch occupies 35-40% more cross-sectional area than cholesterol at surface pressures below film collapse (0-22 mN/m); whereas S-AV-Ch occupies nearly the same molecular area as cholesterol. Isotherms of POPC or SSM mixed with 0.1 mol fraction of either probe are similar to isotherms of the corresponding mixtures of POPC or SSM with cholesterol. The probes show typical AV absorption (lambda 386, 368, 350 and 256 nm) and fluorescence (lambda 412-435 nm) spectra. Steady-state anisotropies of R-AV-Ch and S-AV-Ch in isotropic medium or liquid-crystalline bilayers are higher than the values obtained for other AV probes reflecting hindered intramolecular mobility of the fluorophore and decreased overall rotational rate of the rigid cholesterol derivatives. This suggestion is confirmed by time-resolved fluorescence experiments which show also, in accordance with monolayer data, that S-AV-Ch is better accommodated in POPC-cholesterol bilayers than R-AV-Ch. Model and natural membranes can be labeled by either injecting the probes via a water-soluble organic solvent or by co-lyophilizing probe and phospholipid prior to vesicle production. Detergent-solubilization studies involving 'raft' lipids showed that S-AV-Ch almost identically mimicked the behavior of cholesterol and that of R-AV-Ch was only slightly inferior. Overall, the data suggest that the AV-labeled cholesterol analogs mimic cholesterol behavior in membrane systems and will be useful in related studies. |
| New functional promoter polymorphism, CETP/-629, in cholesteryl ester transfer protein (CETP) gene related to CETP mass and high density lipoprotein cholesterol levels: role of Sp1/Sp3 in transcriptional regulation Dachet, C., O. Poirier, et al. (2000), Arterioscler Thromb Vasc Biol 20(2): 507-15. Abstract: A new polymorphism located at position -629 (CETP/-629A/C) in the promoter of the cholesteryl ester transfer protein (CETP) gene is described. The -629A allele was associated with lower CETP mass (P<0. 0001) and higher high density lipoprotein cholesterol (P<0.001) than the C allele in a sample of 536 control subjects from the ECTIM study. Transfection studies in HepG2 cells with a luciferase expression vector incorporating a 777-bp fragment of the CETP promoter and containing either A or C at position -629 showed significantly lower luciferase activity with the promoter fragment of the A allele (-25%, P<0.05). By gel-shift assay, DNA-protein interactions were evaluated in nuclear extracts of HepG2 cells with the use of 2 probes (A or C probe) composed of 20 bp of the promoter sequence surrounding the polymorphic site. Two specific complexes of distinct migration rate were identified with the A and the C probe. Competition with an excess of oligonucleotide containing the Sp1 consensus binding site showed that a protein(s) of the Sp transcription factor family was implicated in complex formation with the A probe but not with the C probe. Incubation with specific antibodies indicated that Sp1 and Sp3 bound specifically to the A probe. We introduced mutations in the -629-Sp1 binding site to test its functionality and to define the characteristics of transcription factor binding. We showed, by gel-shift assay, that no nuclear proteins bound to the mutated sequence. Transient transfection of HepG2 cells revealed that the expression of the mutated fragment was significantly increased compared with that of the A promoter fragment (25%, P<0.05). The mutated fragment displayed the same activity as that of the C promoter. These results indicate that Sp1 and/or Sp3 repress CETP promoter activity, whereas nuclear factors binding the C allele are without effect on promoter expression. |
| New guidelines for avoiding heart disease by managing high cholesterol, triglycerides, or related problems in HIV James, J. S. (2003), AIDS Treat News(394): 8. Abstract: These guidelines, based on new heart guidelines for the general public and including HIV-specific issues, have many useful suggestions. |
| New guidelines for blood cholesterol by the National Cholesterol Education Program (NCEP). National Cholesterol Education Program (NCEP) Drown, D. J. and M. M. Engler (1994), Prog Cardiovasc Nurs 9(1): 43-4. |
| New guidelines for low-density lipoprotein levels from the National Cholesterol Education Program (NCEP): a 2004 update Brown, D. J. (2004), Prog Cardiovasc Nurs 19(4): 165. |
| New guidelines from the National Cholesterol Education Program: what is the impact on risk assessment? Lowden, J. A. (2002), J Insur Med 34(1): 26-30. Abstract: The National Cholesterol Education Program has developed a set of guidelines for optimal levels of serum lipids that are recommended to reduce the risk of coronary artery disease. This article compares those values to lipid levels found in insurance applicants. |
| New guidelines on high cholesterol Sherman, F. T. (2001), Geriatrics 56(7): 3-4. |
| New homogeneous HDL-cholesterol assay without the influence of high TG sample using the selective detergent to lipoproteins Ueda, Y., M. Matsui, et al. (2003), J Clin Lab Anal 17(6): 201-8. Abstract: Homogeneous HDL-cholesterol assays have been developed and used widely in routine analysis, but they have been reported to give inaccurate results in patients with hypertriglyceridemia. Recently, a new assay based on a new principle without the influence of triglycerides has also been developed and commercialized. We evaluated the basic performance of this new homogeneous HDL-cholesterol assay and compared it with the conventional polyethylene glycol/cyclodextrin-modified enzyme (PEGME) method using high-triglyceride (TG) samples (TG>8000 mg/L). For samples showing a discrepancy with the conventional method, other precipitation and ultracentrifugation (UC) methods were also used to confirm the values. This new homogeneous assay is based on the selective solubilizing effect of detergent on the different lipoproteins. First, non-HDL free cholesterol is consumed by enzyme and is cleared as a colorless reactant. Then. HDL-cholesterol is selectively solubilized by lipoprotein-specific detergent and reacted with the enzyme. As a result, the precision of this new homogeneous assay was good (CV<2%) over the wide range, and the measurement range was 0 to 2000 mg/L. This method correlated well with the PEGME method, which is a conventional method for normolipidemic samples (y=0.97x-3.1, r=0.994, n=424). It also correlated well with the UC method (y=0.99x+0.3, r=0.989, n=53). Fourteen high-TG samples showed different results from those obtained by the PEGME method. Among these samples, one contained abnormal lipoproteins (probably due to the influence of drug therapy) and gave a significantly different result from that obtained by the PEGME method. However, the values obtained by other methods (precipitation and ultracentrifugation) agreed well with those obtained by this new method. In conclusion, this method shows a good basic performance and is useful for high-TG samples without any interference. Therefore, it is considered to be very practical for a routine test. |
| New immunoseparation-based homogeneous assay for HDL-cholesterol compared with three homogeneous and two heterogeneous methods for HDL-cholesterol Nauck, M., W. Marz, et al. (1998), Clin Chem 44(7): 1443-51. Abstract: We evaluated four new commercial methods for HDL-cholesterol determination. The three completely homogeneous assays were an immunoseparation-based (IS) method from Wako, a polyethylene glycol-modified enzyme (PEG) method from Boehringer Mannheim, and a synthetic polymer-based (SP) method from Genzyme. The fourth method was a new heterogeneous method in which lipoproteins are removed using dextran sulfate-coated magnetic beads and Mg2+ (MB, Reference Diagnostics). We compared these methods with the conventional phosphotungstic acid/MgCl2 precipitation (PTA) procedure. The homogeneous assays had good intraassay imprecision with total CVs <2.3%, whereas the CVs of the MB assay were <5.9%. Adding HDL to serum to achieve HDL-cholesterol (HDL-C) concentrations up to 1000 mg/L revealed nearly complete recoveries in the IS, PEG, and MB assays, whereas the SP assay showed a lower recovery (approximately 70%). The SP HDL-C apparently increased at increasing LDL-cholesterol and VLDL-triglyceride concentrations, whereas the IS, PEG, and MB methods were not influenced by LDL-cholesterol up to 6000 mg/L (MB, 5000 mg/L) and VLDL-triglycerides up to 9000 mg/L. Free fatty acids above approximately 2 mmol/L produced falsely high HDL-C in the IS and SP assays, the error amounting to as much as 50% in some samples. An intermethod comparison in 291 fresh serum samples yielded correlation coefficients of at least r = 0.95 for all assays, when compared with the PTA procedure. The slopes and intercepts of the regression lines were 1.05 and 57 (IS), 1.12 and 9.9 (PEG), 1.00 and 39 (SP), and 1.0 and 38 mg/L (MB), respectively. The new assays are precise and simplify the determination of HDL-C, but in part they lack specificity or are susceptible to interferences, resulting in discrepancies when compared with the established PTA procedure. |
| New insights into how adipocytes sense their triglyceride stores. Is cholesterol a signal? Dugail, I., S. Le Lay, et al. (2003), Horm Metab Res 35(4): 204-10. Abstract: In recent years, our view of adipose tissue has evolved from a passive sink for energy storage to an active tissue producing multiple molecules acting on various tissues in different aspects of energy homeostasis. The production of adipose-derived secretory products is tightly regulated as a function of adipocyte lipid accumulation, but the mechanisms by which fat cells are able to sense the levels of their triglyceride stores still remains largely unknown. This paper reviews new insights into this question taking cholesterol as a potential intracellular signaling molecule. |
| New insights into the genetic regulation of intestinal cholesterol absorption Lammert, F. and D. Q. Wang (2005), Gastroenterology 129(2): 718-34. Abstract: The small intestine is a unique organ providing dietary and reabsorbed biliary cholesterol to the body. However, the molecular mechanisms whereby cholesterol is absorbed have not yet been fully understood. Recent research suggests that the newly identified Niemann-Pick C1-like 1 protein (NPC1L1) is expressed at the apical surface of enterocytes and plays a critical role in the absorption of intestinal cholesterol. Furthermore, adenosine triphosphate (ATP)-binding cassette (ABC) transporters ABCG5 and ABCG8 represent apical sterol export pumps that promote active efflux of cholesterol and plant sterols from enterocytes back into the intestinal lumen for excretion. This provides an explanation why cholesterol absorption is a selective process, with plant sterols and other noncholesterol sterols being absorbed poorly or not at all. These findings strongly support the concept that cholesterol absorption is a multistep process, which is regulated by multiple genes at the enterocyte level. The absorption efficiency of cholesterol is most likely determined by the net effect between influx and efflux of intraluminal cholesterol molecules across the brush border of the enterocyte. Combination therapy using a novel, specific, and potent cholesterol absorption (NPC1L1) inhibitor (ezetimibe) and HMG-CoA reductase inhibitors (statins) offers an efficacious new approach to the prevention and treatment of hypercholesterolemia. |
| New insights into the regulation of HDL metabolism and reverse cholesterol transport Lewis, G. F. and D. J. Rader (2005), Circ Res 96(12): 1221-32. Abstract: The metabolism of high-density lipoproteins (HDL), which are inversely related to risk of atherosclerotic cardiovascular disease, involves a complex interplay of factors regulating HDL synthesis, intravascular remodeling, and catabolism. The individual lipid and apolipoprotein components of HDL are mostly assembled after secretion, are frequently exchanged with or transferred to other lipoproteins, are actively remodeled within the plasma compartment, and are often cleared separately from one another. HDL is believed to play a key role in the process of reverse cholesterol transport (RCT), in which it promotes the efflux of excess cholesterol from peripheral tissues and returns it to the liver for biliary excretion. This review will emphasize 3 major evolving themes regarding HDL metabolism and RCT. The first theme is that HDL is a universal plasma acceptor lipoprotein for cholesterol efflux from not only peripheral tissues but also hepatocytes, which are a major source of cholesterol efflux to HDL. Furthermore, although efflux of cholesterol from macrophages represents only a tiny fraction of overall cellular cholesterol efflux, it is the most important with regard to atherosclerosis, suggesting that it be specifically termed macrophage RCT. The second theme is the critical role that intravascular remodeling of HDL by lipid transfer factors, lipases, cell surface receptors, and non-HDL lipoproteins play in determining the ultimate metabolic fate of HDL and plasma HDL-c concentrations. The third theme is the growing appreciation that insulin resistance underlies the majority of cases of low HDL-c in humans and the mechanisms by which insulin resistance influences HDL metabolism. Progress in our understanding of HDL metabolism and macrophage reverse cholesterol transport will increase the likelihood of developing novel therapies to raise plasma HDL concentrations and promote macrophage RCT and in proving that these new therapeutic interventions prevent or cause regression of atherosclerosis in humans. |
| New insights into the role of the adenosine triphosphate-binding cassette transporters in high-density lipoprotein metabolism and reverse cholesterol transport Brewer, H. B., Jr. and S. Santamarina-Fojo (2003), Am J Cardiol 91(7A): 3E-11E. Abstract: Four adenosine triphosphate-binding cassette (ABC) transporters-ABCA1, ABCG1, ABCG5, and ABCG8-have been identified and shown to modulate cholesterol and lipoprotein metabolism. Recent analyses of ABCA1 indicate that upregulation of ABCA1 in the liver and macrophages of transgenic mice is associated with increased plasma high-density lipoprotein (HDL) cholesterol levels, increased net flux of cholesterol to the liver, and reduced diet-induced atherosclerosis. In ABCA1 transgenic mice, the enhanced expression of hepatic ABCA1 transporters is associated with increased plasma HDL cholesterol levels, suggesting that the liver plays an important role in the levels of plasma HDL cholesterol. Overexpression of ABCG1 in the liver of mice using recombinant ABCG1 vectors results in decreased plasma HDL levels and indicates that ABCG1 can modulate plasma lipoprotein levels in vivo. The potential importance of ABCG1 in reverse cholesterol transport has not been definitively established. Studies in patients with sitosterolemia have identified 2 major new transporters, ABCG5 and ABCG8, that play a pivotal role in the regulation of intestinal cholesterol, plant, and shellfish absorption. Modulation of the expression of ABCG5 and ABCG8 represents an important new mechanism in the regulation of cholesterol absorption in the intestine. The ABC transporters currently represent excellent targets for the development of new drugs for the treatment of patients with increased risk of premature cardiovascular disease. |
| New lower cholesterol levels: How much does it cost? Who is to pay? Lindberg, M. (2004), Ugeskr Laeger 166(49): 4493-4; author reply 4494. |
| New lower cholesterol levels--more debate Lindberg, M. (2005), Ugeskr Laeger 167(3): 307-8; author reply 308-9. |
| New mechanisms in cholesterol gallstone disease Konikoff, F. (1994), Isr J Med Sci 30(2): 168-74. |
| New mechanisms of LDL-cholesterol induced endothelial dysfunction; correction by statins Balligand, J. L. (2002), Bull Mem Acad R Med Belg 157(10-12): 427-31; discussion 431-4. Abstract: High LDL-cholesterol is a risk factor for atherosclerosis and cardiovascular events. Dysfunction of the endothelium, e.g. the impairment of its capacity to produce nitric oxide (NO) is an early step in atherogenesis. We identified a mechanism of endothelial toxicity of LDL-cholesterol that alters the activity of the endothelial isoform of nitric oxide synthase (eNOS) in the absence of changes in its expression (abundance). This effect involves the transcriptional activation of the gene encoding caveolin-1, a structural protein of caveolae that acts as a negative allosteric regulator of eNOS. The effect is proportional to the increase in intracellular cholesterol that modulates caveolin-1 gene transcription, through the Sterol Regulatory Element Binding Protein (SREBP). Treatment of endothelial cells with statins (inhibitors of cholesterol synthesis) abrogates caveolin-1 upregulation and restores eNOS activity in vitro and in vivo in genetically apoE-deficient, hypercholesterolemic mice. |