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The impact of plasma triglyceride and apolipoproteins concentrations on high-density lipoprotein subclasses distribution  

PubMed Central

Objective To investigate the effect of triglyceride (TG) integrates with plasma major components of apolipoproteins in HDL subclasses distribution and further elicited the TG-apolipoproteins (apos) interaction in the processes of high density lipoprotein (HDL) mature metabolic and atherosclerosis related diseases. Methods Contents of plasma HDL subclasses were quantities by two-dimensional gel electrophoresis associated with immunodetection in 500 Chinese subjects. Results Contents of pre?1-HDL, HDL3a, and apoB-100 level along with apoB-100/A-I ratio were significantly increased, whereas there was a significant reduction in the contents of HDL2, apoA-I level as well as apoC-III/C-II ratio with increased TG concentration. Moreover, pre?1-HDL contents is elevated about 9 mg/L and HDL2b contents can be reduced 21 mg/L for 0.5 mmol/L increment in TG concentration. Moreover, with increase of apoA-I levels, HDL2b contents were marginally elevated in any TG concentration group. Furthermore, despite of in the apoB-100/A-I < 0.9 group, the contents of pre?1-HDL increased, and those of HDL2b decreased significantly for subjects in both high and very high TG levels compared to that in normal TG levels. Similarly, in the apoB-100/A-I ? 0.9 group, the distribution of HDL subclasses also showed abnormality for subjects with normal TG levels. Conclusions The particle size of HDL subclasses tend to small with TG levels increased which indicated that HDL maturation might be impeded and efficiency of reverse cholesterol transport(RCT) might be weakened. These data suggest that TG levels were not only significantly associated with but liner with the contents of pre?1-HDL and HDL2b. They also raise the possibility that the TG levels effect on HDL maturation metabolism are subjected to plasma apolipoproteins and apolipoproteins ratios. PMID:21251287



Low density lipoprotein subclasses and response to a low-fat diet in healthy men  

SciTech Connect

Lipid and lipoprotein response to reduced dietary fat intake was investigated in relation to differences in distribution of LDL subclasses among 105 healthy men consuming high-fat (46%) and low-fat (24%) diets in random order for six weeks each. On high-fat, 87 subjects had predominantly large, buoyant LDL as measured by gradient gel electrophoresis and confirmed by analytic ultracentrifugation (pattern A), while the remainder had primarily smaller, denser LDL (pattern B). On low-fat, 36 men changed from pattern A to B. Compared with the 51 men in the stable A group, men in the stable B group (n = 18) had a three-fold greater reduction in LDL cholesterol and significantly greater reductions in plasma apoB and mass of intermediate (LDL II) and small (LDL III) LDL subtractions measured by analytic ultracentrifugation. In both stable A and change groups, reductions in LDL-cholesterol were not accompanied by reduced plasma apoB, consistent with the observation of a shift in LDL particle mass from larger, lipid-enriched (LDL I and II) to smaller, lipid-depleted (LDL III and IV) subfractions, without significant change in particle number. Genetic and environmental factors influencing LDL subclass distributions thus may also contribute substantially to interindividual variation in response to a low-fat diet.

Krauss, R.M.; Dreon, D.M. [Lawrence Berkeley Lab., CA (United States). Life Sciences Div.



Quantitative and compositional changes in high density lipoprotein subclasses in patients with various genotypes of cholesteryl ester transfer protein deficiency  

Microsoft Academic Search

High density lipoprotein (HDL) with and without apolipoprotein (apo) E was quantified and characterized in subjects with three genotypes of cholesteryl ester transfer pro- tein (CETP) deficiency: the nonsense mutation in intron 14 (10 homozygotes and 5 heterozygotes); the missense mutation in the exon 15 (3 homozygotes and 9 heterozygotes); and the Int14A\\/D442G in 6 compound heterozygotes. ApoE-poor and apoE-rich

Hitoshi Chiba; Harukuni Akita; Shu-Ping Hi; Yukihiro Takahashi; Hirotoshi Fuda; Haruki Suzuki; Hitoshi Shibuya; Masahiro Tsuji; Kunihiko Kobayashit


Preparation of fatty acid methyl esters from lipoprotein and macrophage lipid subclasses on thin-layer plates  

Microsoft Academic Search

A simple, accurate, and fast procedure for quantitative analysis of fatty acids (FA) in simple lipid subclasses from different\\u000a biological specimens is presented. Lipid extracts of isolated plasma lipoproteins (very low, low, and high density lipoproteins;\\u000a VLDL, LDL, and HDL, respectively) and permanent J774 mouse macrophages were fractionated into lipid subclasses by thin-layer\\u000a chromatography (TLC) on silica gel 60 plates.

Wolfgang Sattler; Helga Reicher; Pilar Ramos; Ute Panzenboeck; Marianne Hayn; Hermann Esterbauer; Ernst Malle; Gerhard M. Kostner



Effects of extended-release niacin on lipoprotein subclass distribution  

Microsoft Academic Search

The efficacy of extended-release niacin (niacin ER) on lipoprotein subclasses was evaluated in patients with primary hypercholesterolemia using a proton nuclear magnetic resonance method. Paired plasma samples collected at baseline and after 12 weeks’ treatment with niacin ER 1,000 (n = 21) or 2,000 (n = 20) mg\\/day or placebo (n = 19) were available for 60 eligible patients from

John M Morgan; David M Capuzzi; Ronnie I Baksh; Charles Intenzo; Christina M Carey; Dana Reese; Kalen Walker



Reduced beta-strand content in apoprotein B-100 in smaller and denser low-density lipoprotein subclasses as probed by Fourier-transform infrared spectroscopy.  

PubMed Central

The secondary structure of apolipoprotein B-100 in low-density lipoprotein (LDL) subfractions was analysed by Fourier-transform IR spectroscopy. LDLs were isolated in three density ranges by gradient centrifugation of human plasma from healthy volunteers. The spectra revealed differences in the lipid content and composition of the three LDL fractions. The secondary structure of apolipoprotein B-100 was the same in the two fractions corresponding to the large less-dense LDL particles, whereas a lower content of beta-strands was found in the third fraction corresponding to the smaller denser LDL particles. Analysis of the spectroscopic data suggests that, in the same set of LDL subfractions, the particle size is probably the cause of the observed differences in apolipoprotein B-100 secondary structure. PMID:9148747

Tanfani, F; Galeazzi, T; Curatola, G; Bertoli, E; Ferretti, G



Modified Low-Density Lipoproteins and High-Density Lipoproteins  

Microsoft Academic Search

It has long been known that the oxidative state of the various plasma lipoproteins modulates platelet aggregability, thereby contributing to atherogenesis. Low-density lipoprotein (LDL), occurring in vivo both in the native and oxidised forms, interacts directly with platelets, by binding to specific receptors. While the identity of the receptors for native LDL and some subfractions of high-density lipoproteins (HDL) remains

Elisabeth Koller; Ivo Volf; Aner Gurvitz; Franz Koller



Hypertriglyceridemia and unusual lipoprotein subclass distributions associated with late pregnancy  

SciTech Connect

In the human adult population elevated plasma triglyceride (TG) levels are associated with decreased high density lipoprotein-cholesterol (HDL-C) levels and decreased HDL and LDL particle sizes. Late pregnancy is a hypertriglyceridemic state where little is known about LDL and HDL subpopulation distribution. Plasma lipids, apolipoproteins (apo) and lipoprotein subpopulations were examined in 36 pregnant women at 36 wk pregnancy and 6 wk postpartum and correlated with HDL and LDL size. There was a significant decrease in LDL diameter at 36 wk pre, 25 {plus minus} 0.7 nm compared, with 6 wk post, 26.4 {plus minus} 0.8 nm. A total of 97% of the 36 wk pre subjects had small dense LDL which paralleled increases in apoB concentration. Unlike LDL HDL at 36 wks pre showed a significant increase in larger sized particles where HDL{sub 2b} predominated. There was a positive correlation between HDL{sub 2b} mass and apoAl and HDL-C concentrations. Late pregnancy is a metabolic state where the predominance of large, HDL{sub 2b} particles is discordant with the predominance of small LDL and elevated TG. This annual metabolic pattern may in part be due to hormonal changes occurring in late pregnancy.

Forte, T.M.; Kretchmer, N.; Silliman, K. (Lawrence Berkeley Lab., CA (United States))



The effect of atorvastatin on serum lipids, lipoproteins and NMR spectroscopy defined lipoprotein subclasses in type 2 diabetic patients with ischaemic heart disease  

Microsoft Academic Search

The effect of statin therapy on subclasses of LDL, VLDL and HDL lipoproteins is unclear. We compared changes in serum lipids, apolipoproteins and nuclear magnetic resonance (NMR) spectroscopy measured lipoprotein subclass concentration and average particle size over a minimum 6 months treatment period of atorvastatin 10 mg vs. placebo in 122 men and women. All subjects had type 2 diabetes

S. S. Soedamah-Muthu; H. M. Colhoun; M. J. Thomason; D. J. Betteridge; P. N. Durrington; G. A. Hitman; J. H. Fuller; K. Julier; M. I. Mackness; H. A. W. Neil



Lipoprotein particle subclasses, cardiovascular disease and HIV infection  

Microsoft Academic Search

ObjectiveTo study the association of lipoprotein particles with CVD in a subgroup of HIV-infected patients who were enrolled in the Strategies for Management of Anti-Retroviral Therapy (SMART) study. SMART was a trial of intermittent use of ART (drug conservation [DC]) versus continuous of ART (viral suppression [VS]).

Daniel A. Duprez; Lewis H. Kuller; Russell Tracy; James Otvos; David A. Cooper; Jennifer Hoy; Jacqueline Neuhaus; Nicholas I. Paton; Nina Friis-Moller; Fiona Lampe; Angelike P. Liappis; James D. Neaton



Effects of 34 Risk Loci for Type 2 Diabetes or Hyperglycemia on Lipoprotein Subclasses and Their Composition in 6,580 Nondiabetic Finnish Men  

PubMed Central

OBJECTIVE We investigated the effects of 34 genetic risk variants for hyperglycemia/type 2 diabetes on lipoprotein subclasses and particle composition in a large population-based cohort. RESEARCH DESIGN AND METHODS The study included 6,580 nondiabetic Finnish men from the population-based Metabolic Syndrome in Men (METSIM) study (aged 57 ± 7 years; BMI 26.8 ± 3.7 kg/m2). Genotyping of 34 single nucleotide polymorphism (SNPs) for hyperglycemia/type 2 diabetes was performed. Proton nuclear magnetic resonance spectroscopy was used to measure particle concentrations of 14 lipoprotein subclasses and their composition in native serum samples. RESULTS The glucose-increasing allele of rs780094 in GCKR was significantly associated with low concentrations of VLDL particles (independently of their size) and small LDL and was nominally associated with low concentrations of intermediate-density lipoprotein, all LDL subclasses, and high concentrations of very large and large HDL particles. The glucose-increasing allele of rs174550 in FADS1 was significantly associated with high concentrations of very large and large HDL particles and nominally associated with low concentrations of all VLDL particles. SNPs rs10923931 in NOTCH2 and rs757210 in HNF1B genes showed nominal or significant associations with several lipoprotein traits. The genetic risk score of 34 SNPs was not associated with any of the lipoprotein subclasses. CONCLUSIONS Four of the 34 risk loci for type 2 diabetes or hyperglycemia (GCKR, FADS1, NOTCH2, and HNF1B) were significantly associated with lipoprotein traits. A GCKR variant predominantly affected the concentration of VLDL, and the FADS1 variant affected very large and large HDL particles. Only a limited number of risk loci for hyperglycemia/type 2 diabetes significantly affect lipoprotein metabolism. PMID:21421807

Stan?áková, Alena; Paananen, Jussi; Soininen, Pasi; Kangas, Antti J.; Bonnycastle, Lori L.; Morken, Mario A.; Collins, Francis S.; Jackson, Anne U.; Boehnke, Michael L.; Kuusisto, Johanna; Ala-Korpela, Mika; Laakso, Markku



Physical Activity versus Sedentary Behavior: Associations with Lipoprotein Particle Subclass Concentrations in Healthy Adults  

PubMed Central

Background Physical activity (PA) and sedentary behavior (SED) may have independent effects on health and disease. This might be due to PA and SED having distinct effects on lipoprotein metabolism. The aim of this study was to determine associations between lipoprotein subclass particle concentrations (-P) and accelerometer-measured SED and moderate-to-vigorous PA (MVPA) in a sample of healthy adult subjects. Methods Lipoprotein subclass particle concentrations were determined by proton nuclear magnetic resonance spectroscopy, whereas SED and MVPA were measured using Agtigraph GT1M and GT3X+ accelerometers. We obtained valid data in 73 subjects (30 men and 43 women, age 40.5 ± 10.6 years; body mass index 24.0 ± 2.8). Multiple regression analysis was used to determine associations (partial correlations) with lipoproteins. Results Positive associations were detected between SED and small VLDL-P, large LDL-P and TG (partial r = 0.24 to 0.25, p < .047). Corresponding associations were non-significant for MVPA (partial r = -0.12 to 0.04, p > .355). On the contrary, MVPA was positively associated with large HDL-P, average HDL size, Apo A1 and HDL-cholesterol (partial r = 0.28 to 0.50, p < .027), whereas SED was not (partial r = -0.06 to 0.07, p > .607). Conclusion There might be a specific effect of SED versus MVPA on lipoprotein metabolism. However, our results must be interpreted carefully due to possible effect-modification by gender and a low sample size. Thus, our findings should be viewed as preliminary. PMID:24386464

Aadland, Eivind; Andersen, John Roger; Anderssen, Sigmund Alfred; Kvalheim, Olav Martin



Effects of insulin resistance and type 2 diabetes on lipoprotein subclass particle size and concentration determined by nuclear magnetic resonance.  


The insulin resistance syndrome (IRS) is associated with dyslipidemia and increased cardiovascular disease risk. A novel method for detailed analyses of lipoprotein subclass sizes and particle concentrations that uses nuclear magnetic resonance (NMR) of whole sera has become available. To define the effects of insulin resistance, we measured dyslipidemia using both NMR lipoprotein subclass analysis and conventional lipid panel, and insulin sensitivity as the maximal glucose disposal rate (GDR) during hyperinsulinemic clamps in 56 insulin sensitive (IS; mean +/- SD: GDR 15.8 +/- 2.0 mg. kg(-1). min(-1), fasting blood glucose [FBG] 4.7 +/- 0.3 mmol/l, BMI 26 +/- 5), 46 insulin resistant (IR; GDR 10.2 +/- 1.9, FBG 4.9 +/- 0.5, BMI 29 +/- 5), and 46 untreated subjects with type 2 diabetes (GDR 7.4 +/- 2.8, FBG 10.8 +/- 3.7, BMI 30 +/- 5). In the group as a whole, regression analyses with GDR showed that progressive insulin resistance was associated with an increase in VLDL size (r = -0.40) and an increase in large VLDL particle concentrations (r = -0.42), a decrease in LDL size (r = 0.42) as a result of a marked increase in small LDL particles (r = -0.34) and reduced large LDL (r = 0.34), an overall increase in the number of LDL particles (r = -0.44), and a decrease in HDL size (r = 0.41) as a result of depletion of large HDL particles (r = 0.38) and a modest increase in small HDL (r = -0.21; all P < 0.01). These correlations were also evident when only normoglycemic individuals were included in the analyses (i.e., IS + IR but no diabetes), and persisted in multiple regression analyses adjusting for age, BMI, sex, and race. Discontinuous analyses were also performed. When compared with IS, the IR and diabetes subgroups exhibited a two- to threefold increase in large VLDL particle concentrations (no change in medium or small VLDL), which produced an increase in serum triglycerides; a decrease in LDL size as a result of an increase in small and a reduction in large LDL subclasses, plus an increase in overall LDL particle concentration, which together led to no difference (IS versus IR) or a minimal difference (IS versus diabetes) in LDL cholesterol; and a decrease in large cardioprotective HDL combined with an increase in the small HDL subclass such that there was no net significant difference in HDL cholesterol. We conclude that 1) insulin resistance had profound effects on lipoprotein size and subclass particle concentrations for VLDL, LDL, and HDL when measured by NMR; 2) in type 2 diabetes, the lipoprotein subclass alterations are moderately exacerbated but can be attributed primarily to the underlying insulin resistance; and 3) these insulin resistance-induced changes in the NMR lipoprotein subclass profile predictably increase risk of cardiovascular disease but were not fully apparent in the conventional lipid panel. It will be important to study whether NMR lipoprotein subclass parameters can be used to manage risk more effectively and prevent cardiovascular disease in patients with the IRS. PMID:12540621

Garvey, W Timothy; Kwon, Soonho; Zheng, Deyi; Shaughnessy, Sara; Wallace, Penny; Hutto, Amy; Pugh, Kimberly; Jenkins, Alicia J; Klein, Richard L; Liao, Youlian



Low-Density Lipoprotein Apheresis  

PubMed Central

Executive Summary Objective To assess the effectiveness and safety of low-density lipoprotein (LDL) apheresis performed with the heparin-induced extracorporeal LDL precipitation (HELP) system for the treatment of patients with refractory homozygous (HMZ) and heterozygous (HTZ) familial hypercholesterolemia (FH). Background on Familial Hypercholesterolemia Familial hypercholesterolemia is a genetic autosomal dominant disorder that is caused by several mutations in the LDL-receptor gene. The reduced number or absence of functional LDL receptors results in impaired hepatic clearance of circulating low-density lipoprotein cholesterol (LDL-C) particles, which results in extremely high levels of LDL-C in the bloodstream. Familial hypercholesterolemia is characterized by excess LDL-C deposits in tendons and arterial walls, early onset of atherosclerotic disease, and premature cardiac death. Familial hypercholesterolemia occurs in both HTZ and HMZ forms. Heterozygous FH is one of the most common monogenic metabolic disorders in the general population, occurring in approximately 1 in 500 individuals1. Nevertheless, HTZ FH is largely undiagnosed and an accurate diagnosis occurs in only about 15% of affected patients in Canada. Thus, it is estimated that there are approximately 3,800 diagnosed and 21,680 undiagnosed cases of HTZ FH in Ontario. In HTZ FH patients, half of the LDL receptors do not work properly or are absent, resulting in plasma LDL-C levels 2- to 3-fold higher than normal (range 7-15mmol/L or 300-500mg/dL). Most HTZ FH patients are not diagnosed until middle age when either they or one of their siblings present with symptomatic coronary artery disease (CAD). Without lipid-lowering treatment, 50% of males die before the age of 50 and 25% of females die before the age of 60, from myocardial infarction or sudden death. In contrast to the HTZ form, HMZ FH is rare (occurring in 1 case per million persons) and more severe, with a 6- to 8-fold elevation in plasma LDL-C levels (range 15-25mmol/L or 500-1000mg/dL). Homozygous FH patients are typically diagnosed in infancy, usually due to the presence of cholesterol deposits in the skin and tendons. The main complication of HMZ FH is supravalvular aortic stenosis, which is caused by cholesterol deposits on the aortic valve and in the ascending aorta. The average life expectancy of affected individuals is 23 to 25 years. In Ontario, it is estimated that there are 13 to 15 cases of HMZ FH. An Ontario clinical expert confirmed that 9 HMZ FH patients have been identified to date. Diagnosis There are 2 accepted clinical diagnostic criterion for the diagnosis of FH: the Simon Broome FH Register criteria from the United Kingdom and the Dutch Lipid Network criteria from the Netherlands. The criterion supplement cholesterol levels with clinical history, physical signs and family history. DNA-based-mutation-screening methods permit a definitive diagnosis of HTZ FH to be made. However, given that there are over 1000 identified mutations in the LDL receptor gene and that the detection rates of current techniques are low, genetic testing becomes problematic in countries with high genetic heterogeneity, such as Canada. Treatment The primary aim of treatment in both HTZ and HMZ FH is to reduce plasma LDL-C levels in order to reduce the risk of developing atherosclerosis and CAD. The first line of treatment is dietary intervention, however it alone is rarely sufficient for the treatment of FH patients. Patients are frequently treated with lipid-lowering drugs such as resins, fibrates, niacin, statins and cholesterol absorption-inhibiting drugs (ezetimibe). Most HTZ FH patients require a combination of drugs to achieve or approach target cholesterol levels. A small number of HTZ FH patients are refractory to treatment or intolerant to lipid-lowering medication. According to clinical experts, the prevalence of refractory HTZ FH in Ontario is between 1 to 5%. Using the mean of 3%, it is estimated that there are approximately 765 refractory HTZ FH patients in Ontario, of which 115 are diagnosed



In vitro Catabolism of very low density lipoproteins from horse ( Equus caballus) by the action of autologous lipoprotein lipase  

Microsoft Academic Search

Incubation of equine very low density lipoproteins with lipoprotein lipase isolated from horse postheparin plasma resulted in the formation of lipoproteins of a higher density. Lipoproteins isolated after incubation and plasma lipoproteins had a different chemical composition and triacylglycerol fatty acid pattern. In vitro-obtained low density lipoproteins contained substantially more phospholipids and triacylglycerols but significantly less cholesteryl esters than native

Carolin S. Stachel; Hubert O. Weik



Changes in lipoprotein(a), oxidized phospholipids, and LDL subclasses with a low-fat high-carbohydrate diet  

PubMed Central

Low-fat diets have been shown to increase plasma concentrations of lipoprotein(a) [Lp(a)], a preferential lipoprotein carrier of oxidized phospholipids (OxPLs) in plasma, as well as small dense LDL particles. We sought to determine whether increases in plasma Lp(a) induced by a low-fat high-carbohydrate (LFHC) diet are related to changes in OxPL and LDL subclasses. We studied 63 healthy subjects after 4 weeks of consuming, in random order, a high-fat low-carbohydrate (HFLC) diet and a LFHC diet. Plasma concentrations of Lp(a) (P < 0.01), OxPL/apolipoprotein (apo)B (P < 0.005), and OxPL-apo(a) (P < 0.05) were significantly higher on the LFHC diet compared with the HFLC diet whereas LDL peak particle size was significantly smaller (P < 0.0001). Diet-induced changes in Lp(a) were strongly correlated with changes in OxPL/apoB (P < 0.0001). The increases in plasma Lp(a) levels after the LFHC diet were also correlated with decreases in medium LDL particles (P < 0.01) and increases in very small LDL particles (P < 0.05). These results demonstrate that induction of increased levels of Lp(a) by an LFHC diet is associated with increases in OxPLs and with changes in LDL subclass distribution that may reflect altered metabolism of Lp(a) particles. PMID:20713651

Faghihnia, Nastaran; Tsimikas, Sotirios; Miller, Elizabeth R.; Witztum, Joseph L.; Krauss, Ronald M.



High density lipoproteins and coronary heart disease  

Microsoft Academic Search

An inverse relationship between the concentration of high density lipoprotein (HDL) cholesterol and the development of coronary heart disease (CHD) is well established. It is unclear from the human studies whether this relationship reflects an ability of HDLs to protect against coronary disease or whether a low HDL in coronary patients is simply an epiphenomenon. Recent studies of transgenic mice,

P. J. Barter; K.-A. Rye



Cranberry extract inhibits low density lipoprotein oxidation  

Microsoft Academic Search

Cranberry juice consumption is often used for the treatment of urinary tract infections, but the effect of cranberry juice on heart disease has not been investigated. We evaluated how a cranberry extract containing 1,548 mg gallic acid equivalents\\/liter (initial pH = 2.50) affected low density lipoprotein (LDL) oxidation induced by 10 micromolar cupric sulfate. When LDL oxidation took place in

Ted Wilson; John P. Porcari; Daniel Harbin



Six new loci associated with blood low-density lipoprotein cholesterol, high-density lipoprotein cholesterol or triglycerides in humans  

Technology Transfer Automated Retrieval System (TEKTRAN)

Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol are risk factors for cardiovascular disease and blood triglycerides reflect key metabolic processes including sensitivity to insulin. Blood lipoprotein and lipid concentrations are heritable. To date, the identification o...


Low-density lipoprotein apheresis: an overview.  


Atherosclerosis with myocardial infarction, stroke, and peripheral cellular disease still maintains its position at the top of morbidity and mortality statistics in industrialized nations. Established risk factors widely accepted are smoking, arterial hypertension, diabetes mellitus, and central obesity. Furthermore, there is a strong correlation between hyperlipidemia and atherosclerosis. The prognosis of patients suffering from severe hyperlipidemia, sometimes combined with elevated lipoprotein (a) (Lpa) levels, and coronary heart disease (CHD) refractory to diet and lipid-lowering drugs is poor. For such patients, regular treatment with low-density lipoprotein (LDL) apheresis is the therapeutic option. Today, there are four different LDL apheresis systems available: immunoadsorption, heparin-induced extracorporeal LDL/fibrinogen precipitation, dextran sulfate LDL adsorption and LDL hemoperfusion. Regarding the different LDL apheresis systems used, there is no significant difference with respect to the clinical outcome or concerning total cholesterol, LDL, high-density lipoprotein (HDL), or triglyceride concentrations. With respect to elevated Lpa levels, however, the immunoadsorption method seems to be the most effective. In 45 patients (25 women, 20 men) suffering from familial hypercholesterolemia resistant to diet and lipid lowering drugs, low-density lipoprotein (LDL) apheresis was performed over 95.6 +/- 44.7 months. Four different systems (Liposorber, 32 of 45, Kaneka, Osaka, Japan; Therasorb, 6 of 45, Baxter, Munich, Germany; Lipopak, 2 of 45, Pocard, Moscow, Russia; and Dali, 5 of 45, Fresenius, St. Wendel, Germany) were used. With all methods, average reductions of 57% for total cholesterol, 55.9% for LDL, 75.8% for lipoprotein a (Lpa), and 45.9% for triglycerides, and an average increase of 14.3% for HDL were reached. Severe side-effects such as shock or allergic reactions were very rare (0.3%) in all methods. In the course of treatment, an improvement in general well-being and increased performance were experienced by 44 of 45 patients. The present data demonstrate that treatment with LDL apheresis of patients suffering from familial hypercholesterolemia resistant to maximum conservative therapy is very effective and safe even in long-term application. PMID:12887719

Bambauer, Rolf; Schiel, Ralf; Latza, Reinhard



Effect of niacin and atorvastatin on lipoprotein subclasses in patients with atherogenic dyslipidemia  

Microsoft Academic Search

This study was conducted to determine the efficacy of atorvastatin and niacin on lipoprotein subfractions in patients with atherogenic dyslipidemia. This was a multicenter, randomized, open-label, parallel-design study of patients with total cholesterol >200 mg\\/dl, triglycerides between 200 and 800 mg\\/dl, and apolipoprotein B >110 mg\\/dl. Patients were randomly assigned to atorvastatin 10 mg or immediate release niacin 3,000 mg

James M McKenney; Lisa S McCormick; Ernst J Schaefer; Donald M Black; Michael L Watkins



Double Superhelix Model of High Density Lipoprotein*  

PubMed Central

High density lipoprotein (HDL), the carrier of so-called “good” cholesterol, serves as the major athero-protective lipoprotein and has emerged as a key therapeutic target for cardiovascular disease. We applied small angle neutron scattering (SANS) with contrast variation and selective isotopic deuteration to the study of nascent HDL to obtain the low resolution structure in solution of the overall time-averaged conformation of apolipoprotein AI (apoA-I) versus the lipid (acyl chain) core of the particle. Remarkably, apoA-I is observed to possess an open helical shape that wraps around a central ellipsoidal lipid phase. Using the low resolution SANS shapes of the protein and lipid core as scaffolding, an all-atom computational model for the protein and lipid components of nascent HDL was developed by integrating complementary structural data from hydrogen/deuterium exchange mass spectrometry and previously published constraints from multiple biophysical techniques. Both SANS data and the new computational model, the double superhelix model, suggest an unexpected structural arrangement of protein and lipids of nascent HDL, an anti-parallel double superhelix wrapped around an ellipsoidal lipid phase. The protein and lipid organization in nascent HDL envisages a potential generalized mechanism for lipoprotein biogenesis and remodeling, biological processes critical to sterol and lipid transport, organismal energy metabolism, and innate immunity. PMID:19812036

Wu, Zhiping; Gogonea, Valentin; Lee, Xavier; Wagner, Matthew A.; Li, Xin-Min; Huang, Ying; Undurti, Arundhati; May, Roland P.; Haertlein, Michael; Moulin, Martine; Gutsche, Irina; Zaccai, Giuseppe; DiDonato, Joseph A.; Hazen, Stanley L.



Beginning to understand high-density lipoproteins.  


This article reconciles the classic view of high-density lipoproteins (HDL) associated with low risk for cardiovascular disease (CVD) with recent data (genetics studies and randomized clinical trials) casting doubt over the widely accepted beneficial role of HDL regarding CVD risk. Although HDL cholesterol has been used as a surrogate measure to investigate HDL function, the cholesterol content in HDL particles is not an indicator of the atheroprotective properties of HDL. Thus, more precise measures of HDL metabolism are needed to reflect and account for the beneficial effects of HDL particles. Current and emerging therapies targeting HDL are discussed. PMID:25432389

Santos-Gallego, Carlos G; Badimon, Juan J; Rosenson, Robert S



Why are low-density lipoproteins atherogenic?  

PubMed Central

Low-density lipoproteins (LDLs) carry most of the cholesterol in human plasma, and high levels of LDL cholesterol clearly cause heart disease. In recent years, many scientists have focused on elucidating the pathophysiologic steps that lie between elevated levels of LDL in the plasma and atherosclerotic plaques in the arterial wall. A large number of scientific studies indicate that oxidation of LDL within the arterial wall may be an important early step in atherogenesis. The uptake of oxidized LDL by macrophages is a likely explanation for the formation of macrophage foam cells in early atherosclerotic lesions. In addition, oxidized LDL has many other potentially proatherogenic properties. Images PMID:8160466

Young, S G; Parthasarathy, S



Computational Lipidology: Predicting Lipoprotein Density Profiles in Human Blood Plasma  

PubMed Central

Monitoring cholesterol levels is strongly recommended to identify patients at risk for myocardial infarction. However, clinical markers beyond “bad” and “good” cholesterol are needed to precisely predict individual lipid disorders. Our work contributes to this aim by bringing together experiment and theory. We developed a novel computer-based model of the human plasma lipoprotein metabolism in order to simulate the blood lipid levels in high resolution. Instead of focusing on a few conventionally used predefined lipoprotein density classes (LDL, HDL), we consider the entire protein and lipid composition spectrum of individual lipoprotein complexes. Subsequently, their distribution over density (which equals the lipoprotein profile) is calculated. As our main results, we (i) successfully reproduced clinically measured lipoprotein profiles of healthy subjects; (ii) assigned lipoproteins to narrow density classes, named high-resolution density sub-fractions (hrDS), revealing heterogeneous lipoprotein distributions within the major lipoprotein classes; and (iii) present model-based predictions of changes in the lipoprotein distribution elicited by disorders in underlying molecular processes. In its present state, the model offers a platform for many future applications aimed at understanding the reasons for inter-individual variability, identifying new sub-fractions of potential clinical relevance and a patient-oriented diagnosis of the potential molecular causes for individual dyslipidemia. PMID:18497853

Hübner, Katrin; Schwager, Thomas; Winkler, Karl; Reich, Jens-Georg; Holzhütter, Hermann-Georg



Negatively Cooperative Binding of High-Density Lipoprotein to the HDL Receptor SR-BI  

E-print Network

Scavenger receptor class B, type I (SR-BI), is a high-density lipoprotein (HDL) receptor, which also binds low-density lipoprotein (LDL), and mediates the cellular selective uptake of cholesteryl esters from lipoproteins. ...

Xu, Shangzhe


Indications for low-density lipoprotein apheresis.  


Low-density lipoprotein (LDL) apheresis offers an additional approach to lipid lowering in patients with severe hypercholesterolemia who fail to respond adequately to diet and drug therapy. Well-defined criteria for patient selection have yet to be established for LDL apheresis. This study proposes guidelines based on whether coronary artery disease (CAD) is present and on the degree of LDL cholesterol elevation after treatment with diet and maximal drug therapy. It is reasonable to consider LDL apheresis therapy for: (1) patients with CAD and LDL cholesterol levels > 190 mg/dl; (2) patients without CAD, but at high risk for disease due to an LDL cholesterol level > 250 mg/dl, a first-degree relative with premature CAD, and the presence of > or = 1 additional risk factor. In addition, LDL apheresis is recommended for the management of all patients with homozygous familial hypercholesterolemia due to the very high risk of CAD and the poor response to usual lipid-lowering treatments. PMID:7977068

Gordon, B R; Stein, E; Jones, P; Illingworth, D R



Structures of Discoidal High Density Lipoproteins  

PubMed Central

Conversion of discoidal phospholipid (PL)-rich high density lipoprotein (HDL) to spheroidal cholesteryl ester-rich HDL is a central step in reverse cholesterol transport. A detailed understanding of this process and the atheroprotective role of apolipoprotein A-I (apoA-I) requires knowledge of the structure and dynamics of these various particles. This study, combining computation with experimentation, illuminates structural features of apoA-I allowing it to incorporate varying amounts of PL. Molecular dynamics simulated annealing of PL-rich HDL models containing unesterified cholesterol results in double belt structures with the same general saddle-shaped conformation of both our previous molecular dynamics simulations at 310 K and the x-ray structure of lipid-free apoA-I. Conversion from a discoidal to a saddle-shaped particle involves loss of helicity and formation of loops in opposing antiparallel parts of the double belt. During surface expansion caused by the temperature-jump step, the curved palmitoyloleoylphosphatidylcholine bilayer surfaces approach planarity. Relaxation back into saddle-shaped structures after cool down and equilibration further supports the saddle-shaped particle model. Our kinetic analyses of reconstituted particles demonstrate that PL-rich particles exist in discrete sizes corresponding to local energetic minima. Agreement of experimental and computational determinations of particle size/shape and apoA-I helicity provide additional support for the saddle-shaped particle model. Truncation experiments combined with simulations suggest that the N-terminal proline-rich domain of apoA-I influences the stability of PL-rich HDL particles. We propose that apoA-I incorporates increasing PL in the form of minimal surface bilayers through the incremental unwinding of an initially twisted saddle-shaped apoA-I double belt structure. PMID:19948731

Gu, Feifei; Jones, Martin K.; Chen, Jianguo; Patterson, James C.; Catte, Andrea; Jerome, W. Gray; Li, Ling; Segrest, Jere P.



Atorvastatin treatment beneficially alters the lipoprotein profile and increases low-density lipoprotein particle diameter in patients with combined dyslipidemia and impaired fasting glucose/type 2 diabetes.  


Diabetic dyslipidemia is featured by hypertriglyceridemia, low high-density lipoprotein (HDL) cholesterol levels, and elevated low-density lipoprotein (LDL) cholesterol commonly in the form of small, dense LDL particles. First-line treatment, fibrates versus statins or both, of dyslipidemia in diabetic patients has been the focus of debate. We investigated the potential hypolipidemic effects of atorvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor with good triglyceride lowering properties, in patients with combined dyslipidemia and evidence of impaired fasting glucose or type 2 diabetes. Twenty patients were recruited for the study, and after a 60-day wash out period, baseline measurements of lipoprotein parameters, LDL particle diameter, and apolipoprotein B (apoB) degradation fragments were obtained. The group was then randomized, in a double-blinded manner, into 2 subgroups. Group A received atorvastatin (80 mg) and group B received placebo daily for 60 days. After the first treatment period, all patients were reanalyzed for the above parameters. The treatment regime then crossed over for the second treatment period in which group A received placebo and group B received atorvastatin (80 mg) daily for 60 days. All parameters were remeasured at the end of the study. Treatment with atorvastatin resulted in a statistically significant reduction in total cholesterol (41%), LDL cholesterol (55%), triglycerides (TG) (32%), and apoB (40%). Mean LDL particle diameter significantly increased from 25.29 +/- 0.24 nm (small, dense LDL subclass) to 26.51 < 0.18 nm (intermediate LDL subclass) after treatment with atorvastatin (n = 20, P <.005). At baseline, LDL particles were predominantly found in the small, dense subclass; atorvastatin treatment resulted in a shift in the profile to the larger and more buoyant LDL subclass. Atorvastatin treatment did not produce consistent changes in the appearance of apoB degradation fragments in plasma. Our results suggest that atorvastatin beneficially alters the atherogenic lipid profile in these patients and significantly decreases the density of LDL particles produced resulting in a shift from small, dense LDL to more buoyant and less atherogenic particles. PMID:11887170

Pontrelli, Louisa; Parris, Wendy; Adeli, Khosrow; Cheung, Raphael C



Remodelling of high density lipoproteins by plasma factors  

Microsoft Academic Search

Evidence that the high density lipoproteins (HDL) in human plasma are antiatherogenic has stimulated considerable interest in the factors which regulate their structure and function. Plasma HDL consist of a number of subpopulations of particles of varying size, density and composition. This structural heterogeneity is caused by the continual remodelling of individual HDL subpopulations by various plasma factors. One of

Kerry-Anne Rye; Moira A. Clay; Philip J. Barter



Low-density lipoprotein-apheresis in two patients with extremely elevated lipoprotein (a) levels.  


Two male caucasian patients (36 and 42 years old) with heterozygous familial hypercholesterolemia and extremely elevated lipoprotein Lp(a) concentrations, resistant to diet and lipid-lowering drugs, were treated with low-density lipoprotein (LDL)-apheresis for 55 months (liposorber system, Kaneka, Japan) and 15 months (immunoadsorption system, special Lp(a) columns, Lipopak, Pocard, Russia). Lp(a) dropped on average by 50%, total cholesterol by 27%, LDL-cholesterol by 42%, triglycerides by 43%, and the fibrinogen concentration by 16%. PMID:8844436

Bambauer, R; Schiel, R; Klinkmann, J; Latza, R



Unique character and metabolism of high density lipoprotein (HDL) in fetus  

Microsoft Academic Search

Lipid and lipoprotein profiles, and enzymes for the lipid metabolism were compared between cord and adult blood. Consistent with previous reports, the major lipoprotein in cord blood was high-density lipoprotein (HDL), and that in adult blood was low-density lipoprotein (LDL). The level of apolipoprotein E (apo E) in cord blood was almost equivalent to that in adult blood, while other

Hironori Nagasaka; Hitoshi Chiba; Hideaki Kikuta; Harukuni Akita; Yukihiro Takahashi; Hidekatsu Yanai; Shu-Ping Hui; Hirotoshi Fuda; Hironobu Fujiwara; Kunihiko Kobayashi



Low Density Lipoprotein Undergoes Oxidative Modification in vivo  

Microsoft Academic Search

It has been proposed that low density lipoprotein (LDL) must undergo oxidative modification before it can give rise to foam cells, the key component of the fatty streak lesion of atherosclerosis. Oxidation of LDL probably generates a broad spectrum of conjugates between fragments of oxidized fatty acids and apolipoprotein B. We now present three mutually supportive lines of evidence for

Wulf Palinski; Michael E. Rosenfeld; Seppo Yla-Herttuala; Geoff C. Gurtner; Steve S. Socher; Susan W. Butler; Sampath Parthasarathy; Thomas E. Carew; Daniel Steinberg; Joseph L. Witztum



Effects of human low and high density lipoproteins on the binding of rat intermediate density lipoproteins to rat liver membranes  

SciTech Connect

Upon incubation with rat liver membranes, radioiodinated rat intermediate density lipoproteins (IDL) interacted with at least two binding sites having a low and a high affinity as demonstrated by the curvilinear Scatchard plots obtained from the specific binding data. The purpose of our work was to identify the nature of these binding sites. Human low density lipoproteins (LDL), contain apolipoprotein B only, and human high density lipoproteins (HDL3), containing neither apolipoprotein B nor E, were both capable of decreasing the specific binding of rat /sup 125/I-IDL. The Scatchard analysis clearly revealed that only the low affinity component was affected by the addition of these human lipoproteins. In fact, the low affinity binding component gradually decreased as the amount of human LDL or HDL3 increased in the binding assay. At a 200-fold excess of human LDL or HDL3, the low affinity binding was totally masked, and the Scatchard plot of the specific /sup 125/I-IDL binding became linear. Only the high affinity binding component was left, enabling a precise measurement of its binding parameters. In a series of competitive displacement experiments in which the binding assay contained a 200-fold excess of human LDL or HDL3, only unlabeled rat IDL effectively displaced the binding of rat /sup 125/I-IDL. We conclude that the low affinity binding of rat IDL to rat liver membranes is due to weak interactions with unspecified lipoprotein binding sites. The camouflage of these sites by human lipoproteins makes possible the study of IDL binding to the high affinity component which likely represents the combined effect of IDL binding to both the remnant and the LDL receptors.

Brissette, L.; Nol, S.P.



Complete high-density lipoproteins in nanoparticle corona.  


In a biological environment, nanoparticles immediately become covered by an evolving corona of biomolecules, which gives a biological identity to the nanoparticle and determines its biological impact and fate. Previous efforts at describing the corona have concerned only its protein content. Here, for the first time, we show, using size exclusion chromatography, NMR, and pull-down experiments, that copolymer nanoparticles bind cholesterol, triglycerides and phospholipids from human plasma, and that the binding reaches saturation. The lipid and protein binding patterns correspond closely with the composition of high-density lipoprotein (HDL). By using fractionated lipoproteins, we show that HDL binds to copolymer nanoparticles with much higher specificity than other lipoproteins, probably mediated by apolipoprotein A-I. Together with the previously identified protein binding patterns in the corona, our results imply that copolymer nanoparticles bind complete HDL complexes, and may be recognized by living systems as HDL complexes, opening up these transport pathways to nanoparticles. Apolipoproteins have been identified as binding to many other nanoparticles, suggesting that lipid and lipoprotein binding is a general feature of nanoparticles under physiological conditions. PMID:19438706

Hellstrand, Erik; Lynch, Iseult; Andersson, Astra; Drakenberg, Torbjörn; Dahlbäck, Björn; Dawson, Kenneth A; Linse, Sara; Cedervall, Tommy



The genetic architecture of lipoprotein subclasses in Gullah-speaking African American families enriched for type 2 diabetes: The Sea Islands Genetic African American Registry (Project SuGAR)  

PubMed Central

We sought to partition the genetic and environmental influences on lipoprotein subclasses and identify genomic regions that may harbor genetic variants that influence serum lipoprotein levels in a sample of Gullah-speaking African-Americans. We genotyped 5,974 SNPs in 979 subjects from 418 pedigrees and used the variance component approach to compute heritability estimates, genetic and environmental correlations, and linkage analyses for selected lipoprotein subclasses. The highest heritability estimate was observed for large VLDL particle concentration (0.56 ± 0.14). Mean LDL particle size and small LDL particle concentration (?0.94) had the strongest genetic correlation estimate. The highest logarithm of odds (LOD) score detected (3.0) was on chromosome 6p24 for small LDL particle concentration. The strongest signal, obtained with the reduced sample of diabetic individuals only, was observed on chromosome 20p13 for small LDL particle concentration. The highest bivariate linkage signal (LOD 2.4) was observed on chromosome 6p24 for mean LDL particle size and small LDL particle concentration.jlr Our results suggest a significant genetic contribution to multiple lipoprotein subclasses studied in this sample and that novel loci on chromosomes 6, 10, 16, and 20 may harbor genes contributing to small, atherogenic LDL particle concentration and large, triglyceride-rich VLDL particle concentration. PMID:19783527

Divers, Jasmin; Sale, Michèle M.; Lu, Lingyi; Chen, Wei-Min; Lok, Kerry H.; Spruill, Ida J.; Fernandes, Jyotika K.; Langefeld, Carl D.; Garvey, W. Timothy



Oxidized low density lipoprotein stimulates aortic smooth muscle cell proliferation  

Microsoft Academic Search

We have investigated the effects of oxidized low density lipoproteins (Ox-LDL) on aortic smooth muscle cell (SMC) proliferation and the biosynthesis of glycosphingo- lipids. We found that Ox-LDL exerted a concentration, time, and temperature dependent alteration of cell proliferation and the biosynthesis of lactosylceramide. At low concen- trations (5-10 fig\\/ml medium) Ox-LDL stimulated cell proliferation measured by an increase in

Subroto Chatterjee; Nupur Ghosh



Endogenously labeled low density lipoprotein triglyceride and apoprotein B kinetics  

Microsoft Academic Search

The kinetics of endogenously labeled low density lipoprotein (LDL) triglycerides (TG) and apoprotein B (apoB) have been studied in four normal and in four hyper- lipemic subjects using double tracers. Analysis of the data suggests that most LDL triglycerides turn over about 10 times faster than apoB (0.003\\/min vs. 0.0003imin) and that about 10% of the LDL particles contain most

Claude Malmendier; Mones Berman



Electric Field-induced Redistribution and Postfield Relaxation of Low Density Lipoprotein  

E-print Network

lipoprotein particle binds with high affinity to the cell surface low density lipoprotein-receptor (LDL, nitrobenzoxadiazole;PBS+, phos- phate-buffered saline containing Ca2÷and Mg2+. THE JOURNAL OF CELL BIOLOGY · VOLUME

Tank, David


Low-density lipoprotein apheresis: clinical results with different methods.  


In 40 patients (22 women, 18 men) suffering from familial hypercholesterolemia resistant to diet and lipid lowering drugs, low-density lipoprotein (LDL) apheresis was performed over 84.9 +/- 43.2 months. Four different systems (Liposorber, 28 of 40, Kaneka, Osaka, Japan; Therasorb, 6 of 40, Baxter, Munich, Germany; Lipopak, 2 of 40, Pocard, Moscow, Russia; and Dali, 4 of 40, Fresenius, St. Wendel, Germany) were used. With all methods, average reductions of 50.6% for total cholesterol, 52.2% for LDL, 64.3% for lipoprotein (a) (Lp[a]), and 43.1% for triglycerides, and an average increase of 10.3% for high-density lipoprotein (HDL) were reached. Severe side effects such as shock or allergic reactions were very rare (0.5%) in all methods. In the course of treatment, an improvement in general well being and increased performance were experienced by 39 of 40 patients. Assessing the different apheresis systems used, at the end of the trial, there were no significant differences with respect to the clinical outcome experienced with the patients' total cholesterol, LDL, HDL, and triglyceride concentrations. However, to reduce high Lp(a) levels, the immunoadsorption method with special Lp(a) columns (Lipopak) seems to be most effective: -59% versus -25% (Kaneka) - (Baxter), and -29% (Dali). The present data demonstrate that treatment with LDL apheresis of patients suffering from familial hypercholesterolemia resistant to maximum conservative therapy is very effective and safe even in long-term application. PMID:11879241

Bambauer, Rolf



Imaging and manipulation of high-density lipoproteins.  

PubMed Central

The atomic force microscope (AFM) has been used to image a variety of biological systems, but has rarely been applied to soluble protein-lipid complexes. One of the primary physiological protein-lipid complexes is the high-density lipoproteins (HDL), responsible for the transport of cholesterol from the peripheral tissues and other lipoproteins to the liver. We have used the AFM to directly image discoidal reconstituted HDL (rHDL) particles for the first time. The height of these particles is consistent with a phospholipid bilayer structure, but careful high resolution measurements of particle diameters has indicated that they fuse when adsorbed to mica. Furthermore, it has been demonstrated that the AFM can be used to initiate this bilayer fusion in a controlled manner, allowing the fabrication of stabilized, nanometer scale, phospholipid bilayer "domains." Images FIGURE 1 PMID:9284285

Carlson, J W; Jonas, A; Sligar, S G



The binding of high density lipoproteins to isolated rat hepatocytes.  


The association of 125I-labelled rat high density lipoproteins (125-I-HDL) to suspended rat hepatocytes was studied at 4 degrees C. 125 I-HDL associated to isolated hepatocytes by two processes-one of high and one of low affinity. The cell-association of 125I-HDL exhibited saturation kinetics and was inhibited to varying degrees with both rat and human lipoproteins such as VLDL, LDL and HDL but not by lipoprotein deficient serum or asialo-fetuin. The cell-association of 125I-HDL did not require divalent cations and could be reduced by pronase treatment of the cells. The binding site was clearly different from the receptor for LDL in extrahepatic cells since heparin and apolipoprotein E did not compete and cholesterol ester labelled HDL. The number of binding sites for HDL at 4 degrees C was 2.2 X 10(6) per cell and the association constant (Ka) 8.2 X 10(6) (mol/l)-1. Experiments with HDL labelled with [3H] cholesterol by means of lecithin: cholesterol acyltransferase (LCAT, EC in the cholesterol ester moiety suggested that the same mechanism was responsible for the cell-association of HDL prepared this way. PMID:7256194

Ose, L; Røken, I; Norum, K R; Drevon, C A; Berg, T



21 CFR 866.5600 - Low-density lipoprotein immunological test system.  

...lipoprotein immunological test system. 866.5600 Section...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Immunological Test Systems § 866.5600 Low-density...lipoprotein immunological test system is a device that consists...lipoprotein in serum and other body fluids....



21 CFR 866.5600 - Low-density lipoprotein immunological test system.  

Code of Federal Regulations, 2013 CFR

...lipoprotein immunological test system. 866.5600 Section...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Immunological Test Systems § 866.5600 Low-density...lipoprotein immunological test system is a device that consists...lipoprotein in serum and other body fluids....



21 CFR 866.5600 - Low-density lipoprotein immunological test system.  

Code of Federal Regulations, 2011 CFR

...lipoprotein immunological test system. 866.5600 Section...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Immunological Test Systems § 866.5600 Low-density...lipoprotein immunological test system is a device that consists...lipoprotein in serum and other body fluids....



21 CFR 866.5600 - Low-density lipoprotein immunological test system.  

Code of Federal Regulations, 2010 CFR

...lipoprotein immunological test system. 866.5600 Section...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Immunological Test Systems § 866.5600 Low-density...lipoprotein immunological test system is a device that consists...lipoprotein in serum and other body fluids....



21 CFR 866.5600 - Low-density lipoprotein immunological test system.  

Code of Federal Regulations, 2012 CFR

...lipoprotein immunological test system. 866.5600 Section...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Immunological Test Systems § 866.5600 Low-density...lipoprotein immunological test system is a device that consists...lipoprotein in serum and other body fluids....



Relative atherogenicity and predictive value of non-high-density lipoprotein cholesterol for coronary heart disease  

Technology Transfer Automated Retrieval System (TEKTRAN)

Although low-density lipoprotein cholesterol (LDL-C) is a well-established atherogenic factor for coronary heart disease, it does not completely represent the risk associated with atherogenic lipoproteins in the presence of high triglyceride (TG) levels. Constituent lipoproteins constituting non–hig...


Biomimetic high density lipoprotein nanoparticles for nucleic acid delivery.  


We report a gold nanoparticle-templated high density lipoprotein (HDL AuNP) platform for gene therapy that combines lipid-based nucleic acid transfection strategies with HDL biomimicry. For proof-of-concept, HDL AuNPs are shown to adsorb antisense cholesterylated DNA. The conjugates are internalized by human cells, can be tracked within cells using transmission electron microscopy, and regulate target gene expression. Overall, the ability to directly image the AuNP core within cells, the chemical tailorability of the HDL AuNP platform, and the potential for cell-specific targeting afforded by HDL biomimicry make this platform appealing for nucleic acid delivery. PMID:21319839

McMahon, Kaylin M; Mutharasan, R Kannan; Tripathy, Sushant; Veliceasa, Dorina; Bobeica, Mariana; Shumaker, Dale K; Luthi, Andrea J; Helfand, Brian T; Ardehali, Hossein; Mirkin, Chad A; Volpert, Olga; Thaxton, C Shad



Biomimetic High Density Lipoprotein Nanoparticles For Nucleic Acid Delivery  

PubMed Central

We report a gold nanoparticle-templated high density lipoprotein (HDL AuNP) platform for gene therapy which combines lipid-based nucleic acid transfection strategies with HDL biomimicry. For proof-of-concept, HDL AuNPs are shown to adsorb antisense cholesterylated DNA. The conjugates are internalized by human cells, can be tracked within cells using transmission electron microscopy (TEM), and regulate target gene expression. Overall, the ability to directly image the AuNP core within cells, the chemical tailorability of the HDL AuNP platform, and the potential for cell-specific targeting afforded by HDL biomimicry make this platform appealing for nucleic acid delivery. PMID:21319839

McMahon, Kaylin M.; Mutharasan, R. Kannan; Tripathy, Sushant; Veliceasa, Dorina; Bobeica, Mariana; Shumaker, Dale K.; Luthi, Andrea J.; Helfand, Brian T.; Ardehali, Hossein; Mirkin, Chad A.; Volpert, Olga; Thaxton, C. Shad



Novel therapies focused on the high-density lipoprotein particle.  


Cardiovascular disease (CVD) remains a major burden for morbidity and mortality in the general population, despite current efficacious low-density lipoprotein-cholesterol-lowering therapies. Consequently, novel therapies are required to reduce this residual risk. Prospective epidemiological studies have shown that high-density lipoprotein-cholesterol (HDL-C) levels are inversely correlated with cardiovascular disease risk, and this initiated the quest for HDL-C-increasing therapies. Consequently, several different targets in HDL metabolism have been identified. Initial studies addressing the effect of cholesteryl ester transfer protein inhibition on cardiovascular disease outcome have been discontinued for reasons of futility or increased mortality. As of yet, 2 cholesteryl ester transfer protein inhibitors are still in phase III studies. Other HDL-based interventions, such as apolipoprotein A1-based compounds, ABC-transporter upregulators, selective peroxisome proliferator-activated receptor modulators and lecithin-cholesterol acyltransferase-based therapy, hold great promise for the future. The aim of this review is to provide a comprehensive overview of HDL-targeted pharmaceutical strategies in humans, both in early development as well as in late stage clinical trials. PMID:24385512

van Capelleveen, Julian C; Brewer, H Bryan; Kastelein, John J P; Hovingh, G Kees



Distinct Hepatic Receptors for Low Density Lipoprotein and Apolipoprotein E in Humans  

NASA Astrophysics Data System (ADS)

Since the liver is a central organ for lipid and lipoprotein synthesis and catabolism, hepatic receptors for specific apolipoproteins on plasma lipoproteins would be expected to modulate lipid and lipoprotein metabolism. The role of hepatic receptors for low density lipoproteins and apolipoprotein E-containing lipoproteins was evaluated in patients with complementary disorders in lipoprotein metabolism: abetalipoproteinemia and homozygous familial hypercholesterolemia. In addition, hepatic membranes from a patient with familial hypercholesterolemia were studied and compared before and after portacaval shunt surgery. The results establish that the human liver has receptors for apolipoproteins B and E. Furthermore, in the human, hepatic receptors for low density lipoproteins and apolipoprotein E are genetically distinct and can undergo independent control.

Hoeg, Jeffrey M.; Demosky, Stephen J.; Gregg, Richard E.; Schaefer, Ernst J.; Brewer, H. Bryan



Identification of Scavenger Receptor SR-BI as a High Density Lipoprotein Receptor  

Microsoft Academic Search

High density lipoprotein (HDL) and low density lipoprotein (LDL) are cholesterol transport particles whose plasma concentrations are directly (LDL) and inversely (HDL) correlated with risk for atherosclerosis. LDL catabolism involves cellular uptake and degradation of the entire particle by a well-characterized receptor. HDL, in contrast, selectively delivers its cholesterol, but not protein, to cells by unknown receptors. Here it is

Susan Acton; Attilio Rigotti; Katherine T. Landschulz; Shangzhe Xu; Helen H. Hobbs; Monty Krieger



Fitness, Heart Disease, and High-Density Lipoproteins: A Look at the Relationships.  

ERIC Educational Resources Information Center

The role of fitness in preventing coronary heart disease is explored. Research on high-density lipoprotein, which has been found to be one of the most critical determinants of risk, is reviewed. The relationship between fitness, high-density lipoprotein, and coronary heart disease is assessed, and clinical implications are spelled out. (MT)

McCunney, Robert J.



Inhibition of Low Density Lipoprotein Synthesis by Dietary Omega3 Fatty Acids in Humans  

Microsoft Academic Search

Diets rich in omega-3 fatty acids derived from fish oils lower the plasma concentra- tions of low density lipoproteins (LDL) and very low density lipoproteins in humans. The present study was designed to examine the mechanism(s) by which diets en- riched in omega-3 fatty acids reduce plasma LDL cholesterol levels in normal sub- jects. Seven healthy volunteers with normal plasma

D. Roger Illingworth; William S. Harris; William E. Connor



Serum concentration of high density lipoproteins (HDLs) in leishmaniotic dogs.  


In order to assess whether the concentration of high density lipoproteins (HDLs) changes in leishmaniotic dogs before and after treatment, HDL cholesterol (HDL-Chol and HDL%), C reactive protein (CRP) and activity of the antioxidant enzyme paraoxonase (PON-1) were measured in sera from 10 controls and 10 leishmaniotic dogs. Seven of these latter were sampled also 3, 7, 14, 21 and 28 days after treatment with antimonials and allopurinol. HDL-chol, and PON-1 were low in leishmaniotic dogs at admission and increased after treatment. HDL-chol and HDL% correlated positively with PON-1 and negatively with CRP suggesting that HDLs decrease through an oxidative mechanism. Therefore, HDLs may be used to monitor the magnitude of oxidation associated with inflammation in leishmaniotic dogs. PMID:25440996

Ibba, Fabrizio; Rossi, Gabriele; Meazzi, Sara; Giordano, Alessia; Paltrinieri, Saverio



High-density lipoprotein binding to bovine adrenal cortex membranes.  


Binding studies were performed with bovine adrenal cortex membranes, human 125I-labelled high-density lipoprotein (HDL) and modified photoactivable derivatives of 125I-labelled HDL, namely 125I-labelled HDL-amidinophenylazide and 125I-labelled HDL-amidopropionyldithiophenylazide. The purity of the apolipoprotein composition of the 125I-labelled HDL and photoactivable 125I-labelled HDL used in the binding studies was determined by Coomassie blue and silver staining, and by measuring 125I-labelled cpm after SDS-polyacrylamide gel electrophoresis. About 45% of the 125I-labelled HDL binding to the membranes occurred in the presence of excess EDTA and only unlabelled HDL competed for the binding site. The 125I-labelled interaction with this binding site on the membranes did not require calcium. In addition, 40% of the 125I-labelled HDL binding was to an EDTA-sensitive site, and unlabelled HDL and low-density lipoprotein (LDL) competed for the binding site. Consequently, adrenal cortex membranes have binding sites which show cross reactivity for both HDL and LDL. Modification of 58% of the apolipoprotein lysine residues of 125I-labelled HDL with methylazidophenylimidate, a reagent which maintains the positive charge at lysine residues, had little affect on binding to EDTA-sensitive and insensitive sites. In contrast, modification of 35% of apolipoprotein lysine residues of 125I-labelled HDL with N-succinimidyl(4-azidophenyldithio)propionate, a reagent which converts charged amino lysines to amide bonds, showed binding properties which were almost totally inhibited by EDTA. PMID:6329311

Newton, D E; Shaw, J M



High density lipoprotein level is negatively associated with the increase of oxidized low density lipoprotein lipids after a fatty meal.  


Recent reports show that a fatty meal can substantially increase the concentration of oxidized lipids in low density lipoprotein (LDL). Knowing the LDL-specific antioxidant effects of high density lipoprotein (HDL), we aimed to investigate whether HDL can modify the postprandial oxidative stress after a fatty meal. Subjects of the study (n = 71) consumed a test meal (a standard hamburger meal) rich in lipid peroxides, and blood samples were taken before, 120, 240, and 360 min after the meal. The study subjects were divided into four subgroups according to the pre-meal HDL cholesterol value (HDL subgroup 1, 0.66-0.91; subgroup 2, 0.93-1.13; subgroup 3, 1.16-1.35; subgroup 4, 1.40-2.65 mmol/L). The test meal induced a marked postprandial increase in the concentration of oxidized LDL lipids in all four subgroups. The pre-meal HDL level was associated with the extent of the postprandial rise in oxidized LDL lipids. From baseline to 6 h after the meal, the concentration of ox-LDL increased by 48, 31, 24, and 16% in the HDL subgroup 1, 2, 3, and 4, respectively, and the increase was higher in subgroup 1 compared to subgroup 3 (p = 0.028) and subgroup 4 (p = 0.0081), respectively. The pre-meal HDL correlated with both the amount and the rate of increase of oxidized LDL lipids. Results of the present study show that HDL is associated with the postprandial appearance of lipid peroxides in LDL. It is therefore likely that the sequestration and transport of atherogenic lipid peroxides is another significant mechanism contributing to cardioprotection by HDL. PMID:25359080

Tiainen, Sanna; Ahotupa, Markku; Ylinen, Petteri; Vasankari, Tommi



Proprotein convertases in high-density lipoprotein metabolism  

PubMed Central

The proprotein convertase subtilisin/kexins (PCSKs) are a serine endopeptidase family. PCSK members cleave amino acid residues and modulate the activity of precursor proteins. Evidence from patients and animal models carrying genetic alterations in PCSK members show that PCSK members are involved in various metabolic processes. These studies further revealed the molecular mechanism by which genetic alteration of some PCSK members impairs normal molecular and physiological functions, which in turn lead to cardiovascular disease. High-density lipoprotein (HDL) is anti-atherogenic as it removes excessive amount of cholesterol from blood and peripheral tissues. Several PCSK members are involved in HDL metabolism. PCSK3, PCSK5, and PCSK6 process two triglyceride lipase family members, endothelial lipase and lipoprotein lipase, which are important for HDL remodeling. Recent studies in our lab found evidence that PCSK1 and PCSK9 are also involved in HDL metabolism. A mouse model carrying an amino acid substitution in PCSK1 showed an increase in serum apolipoprotein A1 (APOA1) level. Another mouse model lacking PCSK9 showed a decrease in APOE-containing HDL. In this review, we summarize the role of the five PCSK members in lipid, glucose, and bile acid (BA) metabolism, each of which can influence HDL metabolism. We propose an integrative model in which PCSK members regulate HDL metabolism through various molecular mechanisms and metabolic processes and genetic variation in some PCSK members may affect the efficiency of reverse cholesterol transport. PCSK members are considered as attractive therapeutic targets. A greater understanding of the molecular and physiological functions of PCSK members will improve therapeutic strategies and drug efficacy for cardiovascular disease where PCSK members play critical role, with fewer adverse effects. PMID:24252756



Constitutive Androstane Receptor Activation Decreases Plasma Apolipoprotein B–Containing Lipoproteins and Atherosclerosis in Low-Density Lipoprotein Receptor–Deficient Mice  

PubMed Central

Objective The goal of this study was to determine the impact of the nuclear receptor constitutive androstane receptor (CAR) on lipoprotein metabolism and atherosclerosis in hyperlipidemic mice. Methods and Results Low-density lipoprotein receptor–deficient (Ldlr?/?) and apolipoprotein E–deficient (ApoE?/?) mice fed a Western-type diet were treated weekly with the Car agonist 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) or the vehicle only for 8 weeks. In Ldlr?/? mice, treatment with TCPOBOP induced a decrease in plasma triglyceride and intermediate-density lipoprotein/low-density lipoprotein cholesterol levels (?30% decrease in both cases after 2 months, P<0.01). These mice also showed a significant reduction in the production of very-low-density lipoproteins associated with a decrease in hepatic triglyceride content and the repression of several genes involved in lipogenesis. TCPOBOP treatment also induced a marked increase in the very-low-density lipoprotein receptor in the liver, which probably contributed to the decrease in intermediate-density lipoprotein/low-density lipoprotein levels. Atherosclerotic lesions in the aortic valves of TCPOBOP-treated Ldlr?/? mice were also reduced (?60%, P<0.001). In ApoE?/? mice, which lack the physiological apoE ligand for the very-low-density lipoprotein receptor, the effect of TCPOBOP on plasma cholesterol levels and the development of atherosclerotic lesions was markedly attenuated. Conclusion CAR is a potential target in the prevention and treatment of hypercholesterolemia and atherosclerosis. PMID:21778422

Sberna, Anne-Laure; Assem, Mahfoud; Xiao, Rui; Ayers, Steve; Gautier, Thomas; Guiu, Boris; Deckert, Valérie; Chevriaux, Angélique; Grober, Jacques; Guern, Naig Le; Pais de Barros, Jean-Paul; Moore, David D.; Lagrost, Laurent; Masson, David



The low-density lipoprotein receptor gene family: a cellular Swiss army knife?  

Microsoft Academic Search

The low-density lipoprotein receptor gene family is an evolutionarily conserved group of cell-surface receptors produced by mammals and other organisms. Initially thought to be endocytic receptors that mediate the uptake of lipoproteins, recent findings have shown that these receptors have other roles in a range of cellular processes. Among other activities, members of this family act as signal transducers in

Anders Nykjaer; Thomas E. Willnow



Aging affects high-density lipoprotein composition and function.  


Most coronary deaths occur in patients older than 65years. Age associated alterations in the composition and function of high-density lipoproteins (HDL) may contribute to cardiovascular mortality. The effect of advanced age on the composition and function of HDL is not well understood. HDL was isolated from healthy young and elderly subjects. HDL composition, cellular cholesterol efflux/uptake, anti-oxidant properties and paraoxonase activity were assessed. We observed a 3-fold increase of the acute phase protein serum amyloid A, an increased content of complement C3 and proteins involved in endopeptidase/protease inhibition in HDL of elderly subjects, whereas levels of apolipoprotein E were significantly decreased. HDL from elderly subjects contained less cholesterol but increased sphingomyelin. Most importantly, HDL from elderly subjects showed defective antioxidant properties, lower paraoxonase 1 activity and was more rapidly taken up by macrophages, whereas cholesterol efflux capability was not altered. These findings suggest that aging alters HDL composition, resulting in functional impairment that may contribute to the onset/progression of cardiovascular disease. PMID:23792422

Holzer, Michael; Trieb, Markus; Konya, Viktoria; Wadsack, Christian; Heinemann, Akos; Marsche, Gunther



Particle release in extracorporeal low-density lipoprotein lowering therapies.  


Release of microparticles into the blood during extracorporeal circulation must be kept low because of possibly serious acute and chronic adverse effects. Concentration and size distribution of microparticles were measured during simulated treatments (n = 7) on original equipment for 2 standard low-density lipoprotein (LDL) elimination procedures (DALI 750, Fresenius AG, St. Wendel, Germany and Liposorber, Kaneka Corporation, Osaka, Japan) and compared to hemofiltration solutions. For both systems as well as in hemofiltration solutions, the mean particle concentrations in 500 ml portions gathered from the efferent blood line stayed below 10% of pharmacopoeia standards for infusion solutions (United States Pharmacopoeia, European Pharmacopoeia) in all measured size classes. Although particle concentrations were comparable in all systems, the mean total number of particles > or =2 microm released per session was lowest in the DALI (167,000) compared to the Liposorber (465,000) and hemofiltration solutions (2,240,000). This was mainly due to different total processed blood volumes necessary to achieve the required LDL reduction. PMID:10916063

Martins, K; Ahrenholz, P; Matic, G B; Hofmann, D; Tiess, M; Winkler, R E; Ramlow, W



Tiliroside and gnaphaliin inhibit human low density lipoprotein oxidation.  


Two flavonoids, gnaphaliin and tiliroside, isolated from Helichrysum italicum, were studied in vitro for their capacity to inhibit Cu(2+)-induced human low density lipoprotein (LDL) and diluted plasma oxidation. LDL oxidation was monitored by conjugated diene, thiobarbituric acid-reactive substances (TBARS) formation and electrophoretic mobility on agarose gel. Gnaphaliin and tiliroside increased the lag-phase for diene conjugate production in a dose-dependent manner. The reduction of TBARS production confirmed the antioxidant activity of gnaphaliin and tiliroside with 50% inhibitory concentration (IC(50)) values of 8.0+/-3.9 microM and 7.0+/-2.6 microM respectively. Furthermore, the flavonoids negated the Cu(2+)-induced increase in electrophoretic mobility of LDL. Antioxidant activity of gnaphaliin and tiliroside was significantly different when diluted plasma was oxidised by adding 1 mM CuSO(4). Although both flavonoids again reduced the TBARS production, tiliroside showed higher activity than gnaphaliin (IC(50)=10.6+/-2.5 microM vs. IC(50)>50 microM). In conclusion, tiliroside and gnaphaliin are antioxidants against in vitro Cu(2+)-induced LDL oxidation in the same order of magnitude compared to that of the reference drug, probucol. PMID:17084992

Schinella, Guillermo R; Tournier, Horacio A; Máñez, Salvador; de Buschiazzo, Perla M; Del Carmen Recio, María; Ríos, José Luis



Differential density lipoprotein profiling for the characterization of Lipoprotein(a)  

E-print Network

Lipoprotein(a) (Lp(a)) has been described as an emerging risk factor for cardiovascular disease. The complexity of the Lp(a) molecule sets a challenge for the determination of the risk it represents for the cardiovascular system. The objective...

Espinosa Garcia, Irma Leticia



A comprehensive evaluation of the heparin-manganese precipitation procedure for estimating high density lipoprotein cholesterol  

Microsoft Academic Search

The accurate quantitation of high density lipo- proteins has recently assumed greater importance in view of studies suggesting their negative correlation with coronary heart disease. High density lipoproteins may be estimated by measuring cholesterol in the plasma frac- tion of d > 1.063 g\\/ml. A more practical approach is the specific precipitation of apolipoprotein B (apoB)-contain- ing lipoproteins by sulfated

G. Russell Warnick; John J. Albers


Oxidized low density lipoprotein stimulates aortic smooth muscle cell proliferation.  


We have investigated the effects of oxidized low density lipoproteins (Ox-LDL) on aortic smooth muscle cell (SMC) proliferation and the biosynthesis of glycosphingolipids. We found that Ox-LDL exerted a concentration, time, and temperature dependent alteration of cell proliferation and the biosynthesis of lactosylceramide. At low concentrations (5-10 micrograms/ml medium) Ox-LDL stimulated cell proliferation measured by an increase in the incorporation of [3H]-thymidine in cells and the synthesis of lactosylceramide, but not glucosylceramide synthesis. Oxidized LDL exerted a threefold increase in the incorporation of [3H]-galactose and [3H]-serine in lactosylceramide. The activity of lactosylceramide synthetase; UDP-galactose glucosylceramide beta 1 --> 4 galactosyltransferase (GalT-2), but not glucosylceramide synthetase (GlcT-1) was stimulated by Ox-LDL. On the other hand, LDL suppressed the activity of GalT-2 in these cells. When cells were preincubated with antibody against Ox-LDL or GalT-2 it compromised the Ox-LDL mediated stimulated in cell proliferation and GalT-2 activity. Similarly, D-PDMP an inhibitor of GalT-2 compromised the Ox-LDL mediated effects in cells. In contrast, L-PDMP further stimulated the Ox-LDL mediated cell proliferation and GalT-2 activity. However, preincubation of cells with preimmune rabbit serum IgG failed to abrogate Ox-LDL mediated stimulation in cell proliferation and GalT-2 activity. In sum, we found that Ox-LDL stimulated aortic smooth muscle cell proliferation in culture. This effect resulted from Ox-LDL mediated activation of GalT-2 that produced lactosylceramide. Lactosylceramide in turn, contributed to cell proliferation. Such correlations are supportive of the notion that GalT-2 action mediates the signal transduction of Ox-LDL contributing to cell proliferation. PMID:8724138

Chatterjee, S; Ghosh, N



Low Density Lipoprotein transport in the normal human aortic arch  

PubMed Central

Background: To understand the genesis and progression of atherosclerosis is essential to elucidate the blood flow and the transport of molecules in the cardiovascular system. The purpose of this computational study is to elucidate the relationship between low wall shear stress (WSS) - high site concentration of low density lipoproteins (LDL) and atherosclerotic sites in the normal human aortic arch under physiological flow and mass transport conditions. Methods: The numerical simulation couples the flow equations with the transport equation applying realistic boundary conditions at the wall in terms of blood-side concentration. The blood is considered to be non-Newtonian fluid obeying to the power law. Suitable mass transport conditions are specified at the wall. Results: Aortic arch walls are exposed to cholesterolemic environment although the applied mass and flow conditions refer to normal human geometry and normal mass-flow conditions. The luminal surface LDL concentration varies inversely with the WSS. Regions of high LDL luminal surface concentration do not necessarily co-locate to the sites of lowest WSS. Concave sides of the aortic arch exhibit, relatively to the convex sides, elevated concentration of the LDL. The area averaged normalized LDL concentration over the entire normal aortic arch is 1.267. The daughter aortic arch vessels exhibit, relatively to the main aorta, elevated LDL concentrations. Conclusions: The near wall paths of the velocities might be the most important factor for the elevated LDL concentration at areas located either at the vicinity of bifurcations regions or at high curvature regions. Hippokratia 2014; 18 (3): 221-225. PMID:25694755

Soulis, JV; Dimitrakopoulou, M; Giannoglou, GD



Reconstituted high-density lipoprotein modulates activation of human leukocytes.  


An anti-inflammatory effect of reconstituted High Density Lipoprotein (rHDL) has been demonstrated in atherosclerosis and in sepsis models. An increase of adhesion molecules as well as tissue factor expression on endothelial cells in response to inflammatory or danger signals are attenuated by the treatment with rHDL. Here we show the inhibitory effect of rHDL on the activation of human leukocytes in a whole blood assay as well as on monocyte-derived human dendritic cells (DC). Multiplex analysis of human whole blood showed that phytohaemagglutinin (PHA)-induced secretion of the cytokines IL-1?, IL-1RA, IL-2R, IL-6, IL-7, IL-12(p40), IL-15 and IFN-? was inhibited. Furthermore, an inhibitory effect on the production of the chemokines CCL-2, CCL-4, CCL-5, CXCL-9 and CXCL-10 was observed. Activation of granulocytes and CD14+ monocytes by PHA is inhibited dose-dependently by rHDL shown as decreased up-regulation of ICAM-1 surface expression. In addition, we found a strong inhibitory effect of rHDL on toll-like receptor 2 (TLR2)- and TLR4-mediated maturation of DC. Treatment of DC with rHDL prevented the up-regulation of cell surface molecules CD80, CD83 and CD86 and it inhibited the TLR-driven activation of inflammatory transcription factor NF-?B. These findings suggest that rHDL prevents activation of crucial cellular players of cellular immunity and could therefore be a useful reagent to impede inflammation as well as the link between innate and adaptive immunity. PMID:23967171

Spirig, Rolf; Schaub, Alexander; Kropf, Alain; Miescher, Sylvia; Spycher, Martin O; Rieben, Robert



Reconstituted High-Density Lipoprotein Modulates Activation of Human Leukocytes  

PubMed Central

An anti-inflammatory effect of reconstituted High Density Lipoprotein (rHDL) has been demonstrated in atherosclerosis and in sepsis models. An increase of adhesion molecules as well as tissue factor expression on endothelial cells in response to inflammatory or danger signals are attenuated by the treatment with rHDL. Here we show the inhibitory effect of rHDL on the activation of human leukocytes in a whole blood assay as well as on monocyte-derived human dendritic cells (DC). Multiplex analysis of human whole blood showed that phytohaemagglutinin (PHA)-induced secretion of the cytokines IL-1?, IL-1RA, IL-2R, IL-6, IL-7, IL-12(p40), IL-15 and IFN-? was inhibited. Furthermore, an inhibitory effect on the production of the chemokines CCL-2, CCL-4, CCL-5, CXCL-9 and CXCL-10 was observed. Activation of granulocytes and CD14+ monocytes by PHA is inhibited dose-dependently by rHDL shown as decreased up-regulation of ICAM-1 surface expression. In addition, we found a strong inhibitory effect of rHDL on toll-like receptor 2 (TLR2)- and TLR4-mediated maturation of DC. Treatment of DC with rHDL prevented the up-regulation of cell surface molecules CD80, CD83 and CD86 and it inhibited the TLR-driven activation of inflammatory transcription factor NF-?B. These findings suggest that rHDL prevents activation of crucial cellular players of cellular immunity and could therefore be a useful reagent to impede inflammation as well as the link between innate and adaptive immunity. PMID:23967171

Kropf, Alain; Miescher, Sylvia; Spycher, Martin O.; Rieben, Robert



High-density lipoprotein and atherosclerosis: Roles of lipid transporters.  


Various previous studies have found a negative correlation between the risk of cardiovascular events and serum high-density lipoprotein (HDL) cholesterol levels. The reverse cholesterol transport, a pathway of cholesterol from peripheral tissue to liver which has several potent antiatherogenic properties. For instance, the particles of HDL mediate to transport cholesterol from cells in arterial tissues, particularly from atherosclerotic plaques, to the liver. Both ATP-binding cassette transporters (ABC) A1 and ABCG1 are membrane cholesterol transporters and have been implicated in mediating cholesterol effluxes from cells in the presence of HDL and apolipoprotein A-I, a major protein constituent of HDL. Previous studies demonstrated that ABCA1 and ABCG1 or the interaction between ABCA1 and ABCG1 exerted antiatherosclerotic effects. As a therapeutic approach for increasing HDL cholesterol levels, much focus has been placed on increasing HDL cholesterol levels as well as enhancing HDL biochemical functions. HDL therapies that use injections of reconstituted HDL, apoA-I mimetics, or full-length apoA-I have shown dramatic effectiveness. In particular, a novel apoA-I mimetic peptide, Fukuoka University ApoA-I Mimetic Peptide, effectively removes cholesterol via specific ABCA1 and other transporters, such as ABCG1, and has an antiatherosclerotic effect by enhancing the biological functions of HDL without changing circulating HDL cholesterol levels. Thus, HDL-targeting therapy has significant atheroprotective potential, as it uses lipid transporter-targeting agents, and may prove to be a therapeutic tool for atherosclerotic cardiovascular diseases. PMID:25349649

Uehara, Yoshinari; Saku, Keijiro



Human Endothelial Progenitor Cells Internalize High-Density Lipoprotein  

PubMed Central

Endothelial progenitor cells (EPCs) originate either directly from hematopoietic stem cells or from a subpopulation of monocytes. Controversial views about intracellular lipid traffic prompted us to analyze the uptake of human high density lipoprotein (HDL), and HDL-cholesterol in human monocytic EPCs. Fluorescence and electron microscopy were used to investigate distribution and intracellular trafficking of HDL and its associated cholesterol using fluorescent surrogates (bodipy-cholesterol and bodipy-cholesteryl oleate), cytochemical labels and fluorochromes including horseradish peroxidase and Alexa Fluor® 568. Uptake and intracellular transport of HDL were demonstrated after internalization periods from 0.5 to 4 hours. In case of HDL-Alexa Fluor® 568, bodipy-cholesterol and bodipy-cholesteryl oleate, a photooxidation method was carried out. HDL-specific reaction products were present in invaginations of the plasma membrane at each time of treatment within endocytic vesicles, in multivesicular bodies and at longer periods of uptake, also in lysosomes. Some HDL-positive endosomes were arranged in form of “strings of pearl”- like structures. HDL-positive multivesicular bodies exhibited intensive staining of limiting and vesicular membranes. Multivesicular bodies of HDL-Alexa Fluor® 568–treated EPCs showed multilamellar intra-vacuolar membranes. At all periods of treatment, labeled endocytic vesicles and organelles were apparent close to the cell surface and in perinuclear areas around the Golgi apparatus. No HDL-related particles could be demonstrated close to its cisterns. Electron tomographic reconstructions showed an accumulation of HDL-containing endosomes close to the trans-Golgi-network. HDL-derived bodipy-cholesterol was localized in endosomal vesicles, multivesicular bodies, lysosomes and in many of the stacked Golgi cisternae and the trans-Golgi-network Internalized HDL-derived bodipy-cholesteryl oleate was channeled into the lysosomal intraellular pathway and accumulated prominently in all parts of the Golgi apparatus and in lipid droplets. Subsequently, also the RER and mitochondria were involved. These studies demonstrated the different intracellular pathway of HDL-derived bodipy-cholesterol and HDL-derived bodipy-cholesteryl oleate by EPCs, with concomitant. PMID:24386159

Srisen, Kaemisa; Röhrl, Clemens; Meisslitzer-Ruppitsch, Claudia; Ranftler, Carmen; Ellinger, Adolf; Pavelka, Margit; Neumüller, Josef



A Single Chicken Oocyte Plasma Membrane Protein Mediates Uptake of Very Low Density Lipoprotein and Vitellogenin  

Microsoft Academic Search

Specific cell-surface receptors mediate the uptake of plasma proteins into growing oocytes of oviparous species, thereby forming yolk. Quantitatively the most important yolk precursors are the lipoproteins, very low density lipoprotein, and vitellogenin. We show that a single major chicken oocyte plasma membrane protein with an apparent molecular mass of 95 kDa as determined by SDS\\/PAGE under nonreducing conditions is

Stefano Stifani; Dwayne L. Barber; Johannes Nimpf; Wolfgang J. Schneider



HMG-CoA reductase inhibitors suppress macrophage growth induced by oxidized low density lipoprotein  

Microsoft Academic Search

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors ameliorate atherosclerotic diseases in several models of vascular disease. This is largely due to their ability to reduce plasma cholesterol levels in vivo. Proliferation of cellular components is one of the major events in the development and progression of atherosclerotic lesions. We recently demonstrated that oxidized low density lipoprotein (Ox-LDL), a likely atherogenic lipoprotein

Masakazu Sakai; Shozo Kobori; Takeshi Matsumura; Takeshi Biwa; Yoshihiro Sato; Toru Takemura; Hideki Hakamata; Seikoh Horiuchi; Motoaki Shichiri



Degradation of Cationized Low Density Lipoprotein and Regulation of Cholesterol Metabolism in Homozygous Familial Hypercholesterolemia Fibroblasts  

Microsoft Academic Search

Cultured fibroblasts derived from patients with homozygous familial hypercholesterolemia, which lack functional low density lipoprotein (LDL) receptors, fail to bind, take up, or degrade the lipoprotein with high affinity; therefore LDL-cholesterol is not made available for suppression of cholesterol synthesis or activation of cholesteryl ester formation. When LDL was given a positive charge by reaction with N,N-dimethyl-1,3-propanediamine (cationized LDL), the

Sandip K. Basu; Joseph L. Goldstein; Richard G. W. Anderson; Michael S. Brown



Hypochlorite-modified high-density lipoprotein acts as a sink for myeloperoxidase in vitro  

Microsoft Academic Search

Aims Myeloperoxidase (MPO), a cardiovascular risk factor in humans, is an in vivo catalyst for lipoprotein modification via intermediate formation of reactive chlorinating species. Among the different lipopro- tein classes, anti-atherogenic high-density lipoprotein (HDL) represents a major target for modification by hypochlorous acid (HOCl), generated from H2O2 by MPO in the presence of physiological chloride con- centrations. As MPO was

Gunther Marsche; Paul G. Furtmuller; Christian Obinger; Wolfgang Sattler; Ernst Malle



Human serum paraoxonase (PON 1) is inactivated by oxidized low density lipoprotein and preserved by antioxidants  

Microsoft Academic Search

Human serum paraoxonase (PON1) can protect low density lipoprotein (LDL) from oxidation induced by either copper ion or by the free radical generator azo bis amidinopropane hydrochloride (AAPH). During LDL oxidation in both of these systems, a time-dependent inactivation of PON arylesterase activity was observed. Oxidized LDL (Ox-LDL) produced by lipoprotein incubation with either copper ion or with AAPH, indeed

Michael Aviram; Mira Rosenblat; Scott Billecke; John Erogul; Robert Sorenson; Charles L Bisgaier; Roger S Newton; Bert La Du



Composition and Distribution of Low Density Lipoprotein Fractions in Hyperapobetalipoproteinemia, Normolipidemia, and Familial Hypercholesterolemia  

Microsoft Academic Search

Hyperapobetalipoproteinemia is defined as the combination of a normal low density lipoprotein (LDL) cholesterol in the face of an increased LDL apolipoprotein B (apoB) protein. To examine the physical basis for the apparent disproportion between LDL cholesterol and apoB characteristic of this syndrome, we used density gradient ultracentrifugation to isolate LDL fractions from 10 normal subjects, from 20 patients with

B. Teng; G. R. Thompson; A. D. Sniderman; T. M. Forte; R. M. Krauss; P. O. Kwiterovich



Very old adults with better memory function have higher low-density lipoprotein cholesterol levels and lower triglyceride to high-density lipoprotein cholesterol ratios: KOCOA project  

PubMed Central

We examined cross-sectionally which lipid profiles are associated with better cognitive function among those aged 80 and older-free of dementia (Clinical Dementia Rating ? 0.5), functionally independent and community-dwelling. Our cohort consisted of 193 participants from the “Keys to Optimal Cognitive Aging (KOCOA) Project”, a prospective cohort study in Okinawa, Japan. Higher low-density lipoprotein cholesterol levels and lower triglyceride/high-density lipoprotein cholesterol (TG/HDL-C) ratios were associated with higher scores in memory performance after controlling for confounders. Further research is required to clarify the associations among LDL-C levels, TG/HDL-C ratios, and healthy cognitive aging. PMID:23207484

Katsumata, Yuriko; Todoriki, Hidemi; Higashiuesato, Yasushi; Yasura, Shotoku; Ohya, Yusuke; Willcox, D. Craig; Dodge, Hiroko H.



Familial apolipoprotein Al and apolipoprotein CIII deficiency: subclass distribution, composition, and morphology of lipoproteins in a disorder associated with premature atherosclerosis  

Microsoft Academic Search

Lipoprotein classes isolated from the plasma of two patients with apolipoprotein AI (apo AI) and apolipoprotein CIII (apo CIII) deficiency were characterized and compared with those of healthy, age- and sex-matched controls. The plasma triglyceride values for patients 1 and 2 were 31 and 51 mg\\/dl, respectively, and their cholesterol values were 130 and 122 mg\\/dl, respectively; the patients, however,

T. M. Forte; A. V. Nichols; R. M. Krauss; R. A. Norum



Sialic acid content of low density lipoprotein and its relation to lipid concentrations and metabolism of low density lipoprotein and cholesterol  

Microsoft Academic Search

A low sialic acid content in low density lipopro- tein (LDL) has been associated with atherogenicity and cor- onary artery disease (CAD) in many but not all studies. We investigated associations of the sialic acid-to-apolipoprotein B (apoB) ratio of LDL with lipoprotein lipid concentra- tions, kinetics of LDL, metabolism of cholesterol, and the presence of CAD in 98 subjects (CAD

Nina Lindbohm; Helena Gylling; Tatu A. Miettinen


Retention of low-density lipoprotein in atherosclerotic lesions of the mouse: evidence for a role of lipoprotein lipase.  


Direct binding of apolipoprotein (apo)B-containing lipoproteins to proteoglycans is the initiating event in atherosclerosis, but the processes involved at later stages of development are unclear. Here, we investigated the importance of the apoB-proteoglycan interaction in the development of atherosclerosis over time and investigated the role of lipoprotein lipase (LPL) to facilitate low-density lipoprotein (LDL) retention at later stages of development. Atherosclerosis was analyzed in apoB transgenic mice expressing LDL with normal (control LDL) or reduced proteoglycan-binding (RK3359-3369SA LDL) activity after an atherogenic diet for 0 to 40 weeks. The initiation of atherosclerosis was delayed in mice expressing RK3359-3369SA LDL, but they eventually developed the same level of atherosclerosis as mice expressing control LDL. Retention studies in vivo showed that although higher levels of 131I-tyramine cellobiose-labeled control LDL (131I-TC-LDL) were retained in nonatherosclerotic aortae compared with RK3359-3369SA 131I-TC-LDL, the retention was significantly higher and there was no difference between the groups in atherosclerotic aortae. Lower levels of control 125I-TC-LDL and RK3359-3369SA 125I-TC-LDL were retained in atherosclerotic aortae from ldlr-/- mice transplanted with lpl-/- compared with lpl+/+ bone marrow. Uptake of control LDL or RK3359-3369SA LDL into macrophages with specific expression of human catalytically active or inactive LPL was increased compared with control macrophages. Furthermore, transgenic mice expressing catalytically active or inactive LPL developed the same extent of atherosclerosis. Thus, retention of LDL in the artery wall is initiated by direct LDL-proteoglycan binding but shifts to indirect binding with bridging molecules such as LPL. PMID:17761930

Gustafsson, Maria; Levin, Malin; Skålén, Kristina; Perman, Jeanna; Fridén, Vincent; Jirholt, Pernilla; Olofsson, Sven-Olof; Fazio, Sergio; Linton, MacRae F; Semenkovich, Clay F; Olivecrona, Gunilla; Borén, Jan



Impaired trafficking of the very low density lipoprotein receptor caused by missense mutations associated with dysequilibrium syndrome.  


Dysequilibrium syndrome (DES, OMIM 224050) is a genetically heterogeneous condition that combines autosomal recessive non-progressive cerebellar ataxia with mental retardation. The subclass dysequilibrium syndrome type 1 (CAMRQ1) has been attributed to mutations in the VLDLR gene encoding the very low density lipoprotein receptor (VLDLR). This receptor is involved in the Reelin signaling pathway that guides neuronal migration in the cerebral cortex and cerebellum. Three missense mutations (c.1459G>T; p.D487Y, c.1561G>C; p.D521H and c.2117G>T; p.C706F) have been previously identified in VLDLR gene in patients with DES. However, the functional implications of those mutations are not known and therefore we undertook detailed functional analysis to elucidate the cellular mechanisms underlying their pathogenicity. The mutations have been generated by site-directed mutagenesis and then expressed in cultured cell lines. Confocal microscopy and biochemical analysis have been employed to examine the subcellular localization and functional activities of the mutated proteins relative to wild type. Our results indicate that the three missense mutations lead to defective intracellular trafficking and ER retention of the mutant VLDLR protein. This trafficking impairment prevents the mutants from reaching the plasma membrane and binding exogenous Reelin, the initiating event in Reelin signaling. Collectively, our results provide evidence that ER quality control is involved in the functional inactivation and underlying pathogenicity of these DES-associated mutations in the VLDLR. PMID:25173816

Kizhakkedath, Praseetha; Loregger, Anke; John, Anne; Bleijlevens, Boris; Al-Blooshi, Ali S; Al-Hosani, Ahmed H; Al-Nuaimi, Ahmed M; Al-Gazali, Lihadh; Zelcer, Noam; Ali, Bassam R



High- and low-density lipoproteins enhance infection of Trypanosoma cruzi in vitro.  


Trypanosoma cruzi exhibits a developmentally regulated neuraminidase activity that is inhibited by high-density lipoprotein (HDL). We report here that the infection of culture cells by T. cruzi trypomastigotes is enhanced by HDL in a dose-dependent manner. The enhanced infection is prevented by Vibrio cholerae neuraminidase, an enzyme whose activity is not inhibited by HDL, suggesting that sialic acid is involved in T. cruzi-host interaction. Similar enhancement of infection is also produced by low-density lipoprotein (LDL), which inhibits T. cruzi neuraminidase as well as HDL. Further evidence that the enhancement is due to lipoproteins is provided by the fact that infection of host cells in lipoprotein-deficient medium is less than in normal medium; it can be restored to the higher level by the addition of HDL, LDL or both to the lipoprotein-deficient medium. In view of these results, we propose that HDL and LDL regulate T. cruzi infection in mammalian hosts by inhibiting the parasite neuraminidase activity. PMID:2183047

Prioli, R P; Rosenberg, I; Pereira, M E



Stimulated arachidonate metabolism during foam cell transformation of mouse peritoneal macrophages with oxidized low density lipoprotein.  

PubMed Central

Changes in arachidonate metabolism were examined in mouse peritoneal macrophages incubated with various types of lipoproteins. Oxidized low density lipoprotein (LDL) was incorporated by macrophages and stimulated macrophage prostaglandin E2 (PGE2) and leukotriene C4 syntheses, respectively, 10.8- and 10.7-fold higher than by the control. Production of 6-keto-PGF1 alpha, a stable metabolite of prostacyclin, was also stimulated. No stimulation was found with native LDL, which was minimally incorporated by the cells. Acetylated LDL and beta-migrating very low density lipoprotein (beta-VLDL), though incorporated more efficiently than oxidized LDL, also had no stimulatory effect. When oxidized LDL was separated into the lipoprotein-lipid peroxide complex and free lipid peroxides, most of the stimulatory activity was found in the former fraction, indicating that stimulation of arachidonate metabolism in the cell is associated with uptake of the lipoprotein-lipid peroxide complex. These results suggest that peroxidative modification of LDL could contribute to the progression of atheroma by stimulating arachidonate metabolism during incorporation into macrophages. Images PMID:3125226

Yokode, M; Kita, T; Kikawa, Y; Ogorochi, T; Narumiya, S; Kawai, C



High Density Lipoprotein-mediated Cholesterol Uptake and Targeting to Lipid Droplets in Intact L-cell Fibroblasts  

E-print Network

High Density Lipoprotein-mediated Cholesterol Uptake and Targeting to Lipid Droplets in Intact L, dehydroergosterol and NBD-cho- lesterol, were used to examine high density lipoprotein- mediated cholesterol uptake, of these sterols differed >100-fold, suggesting significant differences in uptake pathways. NBD-cholesterol uptake

So, Peter


Direct Low Density Lipoprotein Cholesterol and Glycated Albumin Levels in Type 2 Diabetes Mellitus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Diabetes mellitus is a major risk factor for coronary heart disease (CHD), renal failure, retinopathy, and neuropathy. Lowering glycosylated hemoglobin (HbA1c) as well as low-density lipoprotein-cholesterol (LDL-C) have been associated with a decreased risk of these complications. The aim in this st...


Glycated albumin and direct low density lipoprotein cholesterol levels in type 2 diabetes mellitus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Diabetes mellitus is a major risk factor for coronary heart disease (CHD), renal failure, retinopathy, and neuropathy. Lowering glycosylated hemoglobin (HbA1c) as well as low-density lipoprotein-cholesterol (LDL-C) has been associated with a decreased risk of these complications. We evaluated the ut...


Scavenger Receptor Class B Type I Protein as an Independent Predictor of High-Density Lipoprotein  

E-print Network

Scavenger Receptor Class B Type I Protein as an Independent Predictor of High-Density Lipoprotein, Kentucky 40507 Context: In mice, scavenger receptor class B, type I (SR-BI) receptor protein deficiency, is the scavenger re- ceptor, class B, type I (SR-BI) receptor. SR-BI was isolated and characterized

Terasaki, Mark


Macrophage Oxidation of Low Density Lipoprotein Generates a Modified Form Recognized by the Scavenger Receptor  

Microsoft Academic Search

Incubation of low density lipoprotein (LDL) with endothelial cells or smooth muscle cells overnight has resulted in an oxtdative modification of LDL that results in its recognition by macrophages by way of the acetyl LDL receptor. In the present study, we examined whether macrophages themselves can oxidize and modify LDL in a manner similar to that of endothelial cells. Incubation

Sampath Parthasarathy; David J. Printz; Donna Boyd; Lorna Joy; Daniel Steinberg



Boca-dependent maturation of b-propeller/EGF modules in low-density lipoprotein receptor  

E-print Network

Boca-dependent maturation of b-propeller/EGF modules in low-density lipoprotein receptor proteins ortholog, Mesoderm development, in the mouse. All LDLRs have at least one six-bladed b-propeller domain is specifically required for the maturation of these b-propeller/EGF modules through the secretory pathway

Springer, Timothy A.


Hepatitis C Virus and other Flaviviridae Viruses Enter Cells via Low Density Lipoprotein Receptor  

Microsoft Academic Search

Endocytosis of the Flaviviridae viruses, hepatitis C virus, GB virus C\\/hepatitis G virus, and bovine viral diarrheal virus (BVDV) was shown to be mediated by low density lipoprotein (LDL) receptors on cultured cells by several lines of evidence: by the demonstration that endocytosis of these virus correlated with LDL receptor activity, by complete inhibition of detectable endocytosis by anti-LDL receptor

Vincent Agnello; Gyorgy Abel; Mutasim Elfahal; Glenn B. Knight; Qing-Xiu Zhang



Comparison of HOCl traps with myeloperoxidase inhibitors in prevention of low density lipoprotein oxidation  

E-print Network

Comparison of HOCl traps with myeloperoxidase inhibitors in prevention of low density lipoprotein. Therefore, this method was used to subsequently compare the effectiveness of MPO inhibitors that block production of HOCl with compounds that act as HOCl traps. The efficiency of MPO inhibitors to prevent LDL

Hammel, Michal - School of Biological Sciences, University of Missouri


Effect of ingestion of virgin olive oil on human low-density lipoprotein composition  

Microsoft Academic Search

Objective: To measure the incorporation of oleic acid and antioxidants (phenols and vitamin E) to low density lipoprotein (LDL) after acute and short-term ingestion of virgin olive oil. To study whether this incorporation contributes to an increase in LDL resistance to oxidation.Setting: Department of Food and Nutrition, University of Barcelona, Spain and Department of Lipids and Cardiovascular Epidemiology, IMIM, Barcelona,

E Gimeno; M Fitó; RM Lamuela-Raventós; AI Castellote; M Covas; M Farré; MC de la Torre-Boronat; MC López-Sabater



Influence of Flavonols As in vitro on Low Density Lipoprotein Glycation  

Microsoft Academic Search

Introduction. The non-enzymatic glycation of Low density lipoprotein (LDL) is a naturally occurring chemical modification of apolipoprotein B as a result of condensation between lysine residues and glucose. Glycated LDL is poorly recognized by LDL receptors and initiates different processes that can be considered proatherogenic. Thus, LDL glycation may contribute in the increased atherosclerotic risk of patients with diabetes. The

Mohammad Ali Ghaffari; Samad Mojab



Total and High-Density Lipoprotein Cholesterol in Adults with Mental Retardation.  

ERIC Educational Resources Information Center

The study evaluated the total cholesterol and high density lipoprotein cholesterol of 40 adults (mean age 37.5 years) with mental retardation residing at an intermediate care facility. Results indicated that 59 percent of the males and 68 percent of the females were at moderate to high risk for coronary heart disease. (DB)

Rimmer, James H.; Kelly, Luke E.



Oxidative structural modifications of low density lipoprotein in homozygous familial hypercholesterolemia  

Microsoft Academic Search

Patients with homozygous familial hypercholesterolemia (FH), as a result of the increased levels and prolonged residence time of low density lipoprotein (LDL) in plasma, have a strong tendency toward accumulation of LDL-cholesterol in the arterial wall, causing premature atherosclerosis. This phenomenon may enhance per se the physiological degradation of both protein and lipid component of LDL, which be more susceptible

Claudio Napoli; Alfredo Postiglione; Massimo Triggiani; Gaetano Corso; Giuseppe Palumbo; Virginia Carbone; Antonio Ruocco; Giuseppe Ambrosio; Silvana Montefusco; Antonio Malorni; Mario Condorelli; Massimo Chiariello



The effects of gliclazide and other sulfonylureas on low-density lipoprotein oxidation in vitro  

Microsoft Academic Search

Diabetes is associated with increased oxidant stress. This may contribute to the development of diabetic macrovascular complications through increased oxidation of low-density lipoprotein (LDL), which is thought to be a crucial step in the development of atherosclerosis. The sulfonylurea gliclazide has been shown to have free radical—scavenging activity in vitro, but its effects on LDL oxidation, and these effects of

Richard C. O'Brien; Ming Luo



Apple Juice Consumption Reduces Plasma Low-Density Lipoprotein Oxidation in Healthy Men and Women  

Microsoft Academic Search

Epidemiological studies show that consumption of fruits and vegetables is associated with beneficial effects on human health including reduced risk of coronary artery disease (CAD). Fruits and their juices contain phytochemicals that inhibit in vitro low-density lipoprotein (LDL) oxidation and may account, in part, for their protective effect. However, reports of in vivo antioxidant effects from fruit intake are limited.




Association of low-density lipoprotein oxidation to abnormal electrocardiographic late potentials.  


In vivo oxidation of low-density lipoprotein is shown to be significantly related to another risk factor for coronary atherosclerosis, abnormal electrocardiographic late potentials, in clinically healthy pilots. Because both of these variables have been also associated with cardiac arrhythmogenic action, together they may improve the identification of patients at risk of ventricular tachyarrhythmias. PMID:10363876

Kääpä, P; Vihervaara, H; Ahotupa, M



Hypochlorite induces the formation of LDL ?, a potentially atherogenic low density lipoprotein subspecies  

Microsoft Academic Search

Oxidation of low density lipoprotein (LDL) induced by hypochlorous acid (HOCl) leading to LDL?, a minimally oxidized subspecies of LDL, was investigated. LDL? is characterized by its greater electronegativity and oxidative status, and is found in plasma in vivo. Its concentration was found to be elevated under conditions that predispose humans to atherosclerosis. We found that HOCl also converts LDL

Judith S. Fabjan; R. Joerg Schaur; Alex Sevanian




Technology Transfer Automated Retrieval System (TEKTRAN)

An elevated low density lipoprotein cholesterol (LDL-C) level is an independent risk factor for premature coronary heart disease (CHD), with a value of $160 mg/dL designated as high-risk by the National Cholesterol Education Program Adult Treatment Panels I and II. Goals of therapy for all patients...


Impact of Combined Deficiency of Hepatic Lipase and Endothelial Lipase on the Metabolism of Both High-Density Lipoproteins and Apolipoprotein B–Containing Lipoproteins  

PubMed Central

Rationale Hepatic lipase (HL) and endothelial lipase (EL) are extracellular lipases that both hydrolyze triglycerides and phospholipids and display potentially overlapping or complementary roles in lipoprotein metabolism. Objective We sought to dissect the overlapping roles of HL and EL by generating mice deficient in both HL and EL (HL/EL-dko) for comparison with single HL-knockout (ko) and EL-ko mice, as well as wild-type mice. Methods and Results Reproduction and viability of the HL/EL-dko mice were impaired compared with the single-knockout mice. The plasma levels of total cholesterol, high-density lipoprotein (HDL) cholesterol, non–HDL cholesterol, and phospholipids in the HL/EL-dko mice were markedly higher than those in the single-knockout mice. Most notably, the HL/EL-dko mice exhibited an unexpected substantial increase in small low-density lipoproteins. Kinetic studies with [3H]cholesteryl ether–labeled very-low-density lipoproteins demonstrated that the HL/EL-dko mice accumulated counts in the smallest low-density lipoprotein–sized fractions, as assessed by size exclusion chromatography, suggesting that it arises from lipolysis of very-low-density lipoproteins. HDL from all 3 lipase knockout models had an increased cholesterol efflux capacity but reduced clearance of HDL cholesteryl esters versus control mice. Despite their higher HDL cholesterol levels, neither HL-ko, EL-ko, nor HL/EL-dko mice demonstrated an increased rate of macrophage reverse cholesterol transport in vivo. Conclusions These studies reveal an additive effect of HL and EL on HDL metabolism but not macrophage reverse cholesterol transport in mice and an unexpected redundant role of HL and EL in apolipoprotein B lipoprotein metabolism. PMID:20558822

Brown, Robert J.; Lagor, William R.; Sankaranaravanan, Sandhya; Yasuda, Tomoyuki; Quertermous, Thomas; Rothblat, George H.; Rader, Daniel J.



Enzymatic Modification of Plasma Low Density Lipoproteins in Rabbits: A Potential Treatment for Hypercholesterolemia  

NASA Astrophysics Data System (ADS)

Phospholipase A_2 (EC hydrolyzes certain phospholipids of low density lipoprotein (LDL). Plasma clearance of phospholipase A_2-modified human LDL is up to 17 times faster than that of native human LDL in hypercholesterolemic rabbits. Modification of blood lipoproteins of hypercholesterolemic rabbits was performed by using an extracorporeal circuit containing immobilized phospholipase A_2. After 90-min treatments, nearly 30% decreases in plasma cholesterol concentrations were observed. Erythrocyte, leukocyte, and platelet counts showed no net change after treatment. This technique does not require any fluid replacement or sorbent regeneration and offers a potential approach for lowering serum cholesterol and LDL levels.

Labeque, Regine; Mullon, Claudy J. P.; Ferreira, Joao Paulo M.; Lees, Robert S.; Langer, Robert



Enzymatic modification of plasma low density lipoproteins in rabbits: a potential treatment for hypercholesterolemia.  

PubMed Central

Phospholipase A2 (EC hydrolyzes certain phospholipids of low density lipoprotein (LDL). Plasma clearance of phospholipase A2-modified human LDL is up to 17 times faster than that of native human LDL in hypercholesterolemic rabbits. Modification of blood lipoproteins of hypercholesterolemic rabbits was performed by using an extracorporeal circuit containing immobilized phospholipase A2. After 90-min treatments, nearly 30% decreases in plasma cholesterol concentrations were observed. Erythrocyte, leukocyte, and platelet counts showed no net change after treatment. This technique does not require any fluid replacement or sorbent regeneration and offers a potential approach for lowering serum cholesterol and LDL levels. PMID:8475095

Labeque, R; Mullon, C J; Ferreira, J P; Lees, R S; Langer, R



Minimally modified low density lipoprotein stimulates monocyte endothelial interactions.  

PubMed Central

The effect of minimally modified LDL (MM-LDL) on the ability of large vessel endothelial cells (EC) to interact with monocytes and neutrophils was examined. These LDL preparations, obtained by storage or by mild iron oxidation, were indistinguishable from native LDL to the LDL receptor and were not recognized by the scavenger receptor. Treatment of EC with as little as 0.12 micrograms/ml MM-LDL caused a significant increase in the production of chemotactic factor for monocytes (sevenfold) and increased monocyte binding (three- to fivefold). Monocyte binding was maximal after 4 h of EC exposure to MM-LDL, persisted for 48 h, and was inhibited by cycloheximide. In contrast, neutrophil binding was not increased after 1-24 h of exposure. Activity in the MM-LDL preparations was found primarily in the polar lipid fraction. MM-LDL was toxic for EC from one rabbit but not toxic for the cells from another rabbit or any human umbilical vein EC. The resistant cells became sensitive when incubated with lipoprotein in the presence of cycloheximide, whereas the sensitive strain became resistant when preincubated with sublethal concentrations of MM-LDL. We conclude that exposure of EC to sublethal levels of MM-LDL enhances monocyte endothelial interactions and induces resistance to the toxic effects of MM-LDL. Images PMID:2318980

Berliner, J A; Territo, M C; Sevanian, A; Ramin, S; Kim, J A; Bamshad, B; Esterson, M; Fogelman, A M



Negatively Cooperative Binding of High Density Lipoprotein to the HDL Receptor SR-BI†  

PubMed Central

Scavenger receptor class B, type I (SR-BI) is a high-density lipoprotein (HDL) receptor, which also binds low density lipoprotein (LDL), and mediates the cellular selective uptake of cholesteryl esters from lipoproteins. SR-BI also is a co-receptor for hepatitis C virus and a signaling receptor that regulates cell metabolism. Many investigators have reported that lipoproteins bind to SR-BI via a single class of independent (not interacting), high affinity binding sites (one site model). We have re-investigated the ligand concentration dependence of 125I-HDL binding to SR-BI and SR-BI-mediated specific uptake of [3H]CE from [3H]CE-HDL using an expanded range of ligand concentrations (<1 µg protein/ml, lower than previously reported). Scatchard and non-linear least squares model fitting analyses of the binding and uptake data were both inconsistent with a single class of independent binding sites binding univalent lipoprotein ligands. The data are best fit by models in which SR-BI has either two independent classes of binding sites, or one class of sites exhibiting negative cooperativity due to either classic allostery or ensemble effects (‘ lattice model’). Similar results were observed for LDL. Application of the ‘infinite dilution’ dissociation rate method established that the binding of 125I-HDL to SR-BI at 4 °C exhibits negative cooperativity. The unexpected complexity of the interactions of lipoproteins with SR-BI should be taken into account when interpreting the results of experiments that explore the mechanism(s) by which SR-BI mediates ligand binding, lipid transport and cell signaling. PMID:21254782

Nieland, Thomas J.F.; Xu, Shangzhe; Penman, Marsha; Krieger, Monty



A density gradient ultracentrifugal procedure for the isolation of the major lipoprotein classes from human serum  

Microsoft Academic Search

A density gradient ultracentrifugal procedure is described for the rapid and reproducible isolation of the major lipoprotein classes, VLDL, LDL, HDb, and HDL3, from human serum. A step gradient is constructed from four NaCUKBr solutions varying in density from 1.006 to 1.24 g\\/ml and from 3 ml of serum adjusted to d 1.2 1 glml. Separation is achieved after a

M. John Chapman; Sonia Goldstein; Dominique Lagrange; P. Michel


Severe hypertriglyceridemia, reduced high density lipoprotein, and neonatal death in lipoprotein lipase knockout mice. Mild hypertriglyceridemia with impaired very low density lipoprotein clearance in heterozygotes.  

PubMed Central

Lipoprotein lipase (LPL)-deficient mice have been created by gene targeting in embryonic stem cells. At birth, homozygous knockout pups have threefold higher triglycerides and sevenfold higher VLDL cholesterol levels than controls. When permitted to suckle, LPL-deficient mice become pale, then cyanotic, and finally die at approximately 18 h of age. Before death, triglyceride levels are severely elevated (15,087 +/- 3,805 vs 188 +/- 71 mg/dl in controls). Capillaries in tissues of homozygous knockout mice are engorged with chylomicrons. This is especially significant in the lung where marginated chylomicrons prevent red cell contact with the endothelium, a phenomenon which is presumably the cause of cyanosis and death in these mice. Homozygous knockout mice also have diminished adipose tissue stores as well as decreased intracellular fat droplets. By crossbreeding with transgenic mice expressing human LPL driven by a muscle-specific promoter, mouse lines were generated that express LPL exclusively in muscle but not in any other tissue. This tissue-specific LPL expression rescued the LPL knockout mice and normalized their lipoprotein pattern. This supports the contention that hypertriglyceridemia caused the death of these mice and that LPL expression in a single tissue was sufficient for rescue. Heterozygous LPL knockout mice survive to adulthood and have mild hypertriglyceridemia, with 1.5-2-fold elevated triglyceride levels compared with controls in both the fed and fasted states on chow, Western-type, or 10% sucrose diets. In vivo turnover studies revealed that heterozygous knockout mice had impaired VLDL clearance (fractional catabolic rate) but no increase in transport rate. In summary, total LPL deficiency in the mouse prevents triglyceride removal from plasma, causing death in the neonatal period, and expression of LPL in a single tissue alleviates this problem. Furthermore, half-normal levels of LPL cause a decrease in VLDL fractional catabolic rate and mild hypertriglyceridemia, implying that partial LPL deficiency has physiological consequences. Images PMID:8675619

Weinstock, P H; Bisgaier, C L; Aalto-Setälä, K; Radner, H; Ramakrishnan, R; Levak-Frank, S; Essenburg, A D; Zechner, R; Breslow, J L



Low-density lipoprotein particle size, triglycerides, and high-density lipoprotein cholesterol as risk factors for coronary heart disease in older Japanese-American men.  


Decreased low-density lipoprotein (LDL) particle size is associated with coronary heart disease (CHD) risk among middle-aged Caucasian populations, and has been consistently correlated with increased plasma levels of triglyceride and decreased levels of high-density lipoprotein (HDL) cholesterol. This study examines whether these risk factors predict CHD among older Japanese-American men. With use of the Honolulu Heart Program Lipoprotein Exam 3 (1980 to 1982) as baseline, and 12-year follow-up for CHD events, a nested, case-control study was designed. One hundred forty-five incident CHD cases were identified and matched to 2 controls each. LDL particle diameter (size) was determined by gradient gel electrophoresis. A 10-angstrom (A) decrease in LDL size at baseline was associated with increased risk of incident CHD (relative risk 1.28, 95% confidence interval 1.01 to 1.63). After adjustment for baseline risk factors, the LDL size association was no longer statistically significant (relative risk 1.13, 95% confidence interval 0.86 to 1.49). When principal components analysis was used to define a composite variable for LDL size, triglycerides, and HDL cholesterol, this component predicted CHD independent of smoking, alcohol consumption, physical activity, body mass index, hypertension, diabetes, and beta-blocker use (p <0.01). Therefore, this prospective analysis of data from older, Japanese-American men demonstrated that decreased LDL size is a univariate predictor of incident CHD, and that a composite risk factor of LDL size, triglyceride, and HDL cholesterol was a risk factor for CHD independent of other risk factors. PMID:10946034

Austin, M A; Rodriguez, B L; McKnight, B; McNeely, M J; Edwards, K L; Curb, J D; Sharp, D S



Clinical remission is associated with restoration of normal high-density lipoprotein cholesterol levels in children with malignancies.  


1. Serum lipids and lipoprotein profiles were determined in children affected by different types of malignancies (leukaemias or lymphomas and solid tumours) both before any treatment and after remission of the disease following chemical or surgical therapy. 2. At the time of diagnosis, children bearing tumours showed hypertriglyceridaemia and reduced concentrations of plasma high-density lipoprotein cholesterol levels, the decrease being particularly prominent in patients with haematological tumours. Children bearing solid tumours displayed an increase of total cholesterol, while those with haematological cancer showed decreased phospholipid levels; low-density lipoprotein cholesterol in neoplastic patients was not significantly different from control values. High triacylglycerol and low high-density lipoprotein cholesterol levels were also evident in cancer patients divided according to age into three groups (0-5, 6-10 and 11-15 years) when compared with age-matched control subjects. Similarly, high triacylglycerol and low high-density lipoprotein cholesterol levels were also observed in both male and female children when patients were divided according to sex and compared with corresponding controls. 3. Clinical remission after therapy was accompanied by an increase of high-density lipoprotein cholesterol levels compared with values observed at diagnosis. In contrast, post-treatment levels of triacylglycerol were higher than those observed before therapy. These results support the hypothesis that alterations of high-density lipoprotein cholesterol levels may be related, at least in part, to the rate of tumour growth, while modifications of triacylglycerol levels may be mediated by different mechanisms. PMID:8549065

Dessì, S; Batetta, B; Spano, O; Sanna, F; Tonello, M; Giacchino, M; Tessitore, L; Costelli, P; Baccino, F M; Madon, E



High-density lipoprotein cholesterol as an independent risk factor in cardiovascular disease: assessing the data from Framingham to the Veterans Affairs High--Density Lipoprotein Intervention Trial.  


The Framingham Heart Study found that high-density lipoprotein cholesterol (HDL-C) was the most potent lipid predictor of coronary artery disease risk in men and women >49 years of age. The Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS), in which subjects were randomized to treatment with lovastatin or placebo, also reported a striking benefit of treatment, particularly in patients with HDL-C < or =35 mg/dL at baseline. Treatment with lovastatin was associated with a remarkable 45% reduction in events for this group. The Veterans Affairs HDL Intervention Trial (VA-HIT) randomized subjects to gemfibrozil or placebo. A high proportion of enrolled subjects with low HDL-C also had characteristics of the dysmetabolic syndrome. HDL-C likewise increased by 6% on treatment, total cholesterol was reduced by 4% and triglycerides by 31%. There was no change in low-density lipoprotein cholesterol (LDL-C) levels. These changes in lipid were associated with a cumulative 22% reduction in the trial primary endpoint of all-cause mortality and nonfatal myocardial infarction (MI). Additionally, significant reductions in secondary endpoints including death from coronary artery disease, nonfatal MI, stroke, transient ischemic attack, and carotid endarterectomy were associated with the increase in HDL-C. In VA-HIT, for every 1% increase in HDL-C, there was a 3% reduction in death or MI, a therapeutic benefit that eclipses the benefit associated with LDL-C reduction. PMID:11374850

Boden, W E



Endogenous Androgen Deficiency Enhances Diet-Induced Hypercholesterolemia and Atherosclerosis in Low-Density Lipoprotein Receptor-Deficient Mice  

PubMed Central

Background Despite numerous clinical and animal studies, the role of sex steroid hormones on lipoprotein metabolism and atherosclerosis remain controversial. Objective We sought to determine the effects of endogenous estrogen and testosterone on lipoprotein levels and atherosclerosis using mice fed a low-fat diet with no added cholesterol. Methods Male and female low-density lipoprotein receptor-deficient mice were fed an open stock low-fat diet (10% of kcals from fat) for 2, 4, or 17 weeks. Ovariectomy, orchidectomy, or sham surgeries were performed to evaluate the effects of the presence or absence of endogenous hormones on lipid levels, lipoprotein distribution, and atherosclerosis development. Results Female mice fed the study diet for 17 weeks had a marked increase in levels of total cholesterol, triglycerides, apolipoprotein-B containing lipoproteins, and atherosclerosis compared with male mice. Surprisingly, ovariectomy in female mice had no effect on any of these parameters. In contrast, castration of male mice markedly increased total cholesterol concentrations, triglycerides, apolipoprotein B-containing lipoproteins, and atherosclerotic lesion formation compared with male and female mice. Conclusions These data suggest that endogenous androgens protect against diet-induced increases in cholesterol concentrations, formation of proatherogenic lipoproteins, and atherosclerotic lesions formation. Conversely orchidectomy, which decreases androgen concentrations, promotes increases in cholesterol concentrations, proatherogenic lipoprotein formation, and atherosclerotic lesion formation in lowdensity lipoprotein receptor-deficient mice in response to a low-fat diet. PMID:22981166

Hatch, Nicholas W.; Srodulski, Sarah J.; Chan, Huei-Wei; Zhang, Xuan; Tannock, Lisa R.; King, Victoria L.



Effect of rosuvastatin on low-density lipoprotein cholesterol in patients with hypercholesterolemia  

Microsoft Academic Search

Rosuvastatin is a new, synthetic, orally active statin, with marked low-density lipoprotein (LDL) cholesterol-lowering activity. We conducted 2 dose-ranging studies. In the first study, after a 6-week dietary run-in, 142 moderately hypercholesterolemic patients were randomized equally to receive double-blind placebo or rosuvastatin 1, 2.5, 5, 10, 20, or 40 mg or open-label atorvastatin 10 or 80 mg once daily for

Anders G Olsson; John Pears; John McKellar; Jacques Mizan; Ali Raza



Serum High-Density Lipoprotein Cholesterol, Metabolic Profile, and Breast Cancer Risk  

Microsoft Academic Search

Background: The prevalence of metabolic syndrome (obe- sity, glucose intolerance, low serum high-density lipoprotein cholesterol (HDL-C), high serum triglycerides, hyperten- sion) is high and increasing in parallel with an increasing breast cancer incidence worldwide. HDL-C represents an important aspect of the syndrome, yet its role in breast cancer is still undefined. Methods: In two population-based screening surveys during 1977-1983 and

Anne-Sofie Furberg; Tom Wilsgaard; Leslie Bernstein; Inger Thune



Protective effect of olive oil and its phenolic compounds against low density lipoprotein oxidation  

Microsoft Academic Search

The protective effect of phenolic compounds from an olive oil extract, and of olive oils with (extra-virgin) and without (refined)\\u000a phenolic components, on low density lipoprotein (LDL) oxidation was investigated. When added to isolated LDL, phenolics [0.025–0.3\\u000a mg\\/L caffeic acid equivalents (CAE)] increased the lag time of conjugated diene formation after copper-mediated LDL oxidation\\u000a in a concentration-dependent manner. Concentrations of

Montserrat Fitó; María Isabel Covas; Rosa M. Lamuela-Raventós; Joan Vila; Jaume Torrents; Carmen de la Torre; Jaume Marrugat



Inhibition of human low density lipoprotein oxidation by flavonols and their glycosides  

Microsoft Academic Search

Antioxidative effects of the flavonols and their glycosides, i.e., quercetin (Q), quercetin galactopyranoside (QG), quercetin rhamnolpyranoside (QR), rutin (R), morin (MO), myrecetin (MY), kaempferol (K) and kaempferol glucoside (KG), against free radical initiated peroxidation of human low density lipoprotein (LDL) were studied. The peroxidation was initiated either by a water-soluble initiator 2,2?-azobis(2-amidino propane hydrochloride) (AAPH), or by cupric ion (Cu2+).

Lifen Hou; Bo Zhou; Li Yang; Zhong-Li Liu



A multiexon deletion in the human low density lipoprotein receptor gene causes familial hypercholesterolemia  

SciTech Connect

Familial hypercholesterolemia (FH) is a widespread human disease. FH is caused by a disturbance in the catabolism of low density lipoproteins (LDL), which results from mutations in the LDL receptor gene (LDLR). The majority of mutations in the LDLR locus is represented by large-scale reorganizations in the above gene. In this study, we describe a novel 5 kb deletion, which eliminates exons 4 to 6 in the LDLR gene. 16 refs., 2 figs., 1 tab.

Mandel`shtam, M.Yu.; Lipovetskii, B.M.; Shvartsman, A.L.; Gaitskhoki, V.S. [Institute of Experimental Medicine, St. Petersburg (Russian Federation)



Studies of low density lipoprotein molecular weight in human beings with coronary artery disease  

Microsoft Academic Search

Low density lipoprotein molecular weight (LDL MW) correlates positively with coronary artery disease in cho- lesterol-fed nonhuman primates. To evaluate this in human beings with coronary artery disease (CAD) we measured LDL MW in 93 volunteers undergoing coronary angiography (47 controls and 46 CAD patients). LDL MW of CAD patients was less than that of controls (patients, 2.79 * 0.17

John R. Crouse; Johns S. Parks; Harry M. Schey; Frederic R. Kahl


Inhibitory effects of Du-zhong ( Eucommia ulmoides Oliv.) against low-density lipoprotein oxidative modification  

Microsoft Academic Search

This study presents the effects of water extracts from leaves, raw cortex, and roasted cortex of Du-zhong (Eucommia ulmoides Oliv.) on the oxidative modification of human low-density lipoprotein (LDL) induced by copper ion (Cu2+). Through determination of the formation of thiobarbituric acid-reactive substances (TBARS) and conjugated dienes (CD), as well as relative electrophoretic mobility (REM), all extracts of Du-zhong were

Gow-Chin Yen; Chiu-Luan Hsieh



Absence of Monocyte Chemoattractant Protein1 Reduces Atherosclerosis in Low Density Lipoprotein Receptor–Deficient Mice  

Microsoft Academic Search

Recruitment of blood monocytes into the arterial subendothelium is one of the earliest steps in atherogenesis. Monocyte chemoattractant protein-1 (MCP-1), a CC chemokine, is one likely signal involved in this process. To test MCP-1’s role in atherogenesis, low density lipoprotein (LDL) receptor–deficient mice were made genetically deficient for MCP-1 and fed a high cholesterol diet. Despite having the same amount

Long Gu; Yoshikatsu Okada; Steven K. Clinton; Craig Gerard; Galina K. Sukhova; Peter Libby; Barrett J. Rollins



Tomato lycopene and low density lipoprotein oxidation: A human dietary intervention study  

Microsoft Academic Search

Increase in low density lipoprotein (LDL) oxidation is hypothesized to be causally associated with increasing risk of atherosclerosis\\u000a and coronary heart disease. In recent epidemiological studies, tissue and serum levels of lycopene, a carotenoid available\\u000a from tomatoes, have been found to be inversely related to risk of coronary heart disease. A study was undertaken to investigate\\u000a the effect of dietary

Sanjiv Agarwal; A. Venketeshwer Rao



Lymphocyte T subset counts in children with elevated low-density lipoprotein cholesterol levels  

Microsoft Academic Search

The aim of this study was to determine blood lymphocyte T subset counts in children with elevated levels of low-density lipoprotein cholesterol. We studied 107 children, ages 2.0 to 15.9 years, from 79 families who were referred to our Lipid Research Clinic because total cholesterol serum levels higher than 200 mg\\/dl had been detected in at least one child. At

A. Sarría; L. A. Moreno; M. Mur; A. Lázaro; M. P. Lasierra; L. Roda; A. Giner; L. Larrad; M. Bueno



Predicting the structure of apolipoprotein A-I in reconstituted high-density lipoprotein disks.  

PubMed Central

In reconstituted high-density lipoproteins, apolipoprotein A-I and phosphatidylcholines combine to form disks in which the amphipathic alpha-helices of apolipoprotein A-1 bind to the edge of a lipid bilayer core, shielding the hydrophic lipid tails from the aqueous environment. We have employed experimental data, sequence analysis, and molecular modeling to construct an atomic model of such a reconstituted high-density lipoprotein disk consisting of two apolipoprotein A-I proteins and 160 palmitoyloleoylphosphatidylcholine lipids. The initial globular domain (1-47) of apolipoprotein A-I was excluded from the model, which was hydrated with an 8-A shell of water molecules. Molecular dynamics and simulated annealing were used to test the stability of the model. Both head-to-tail and head-to-head forms of a reconstituted high-density lipoprotein were simulated. In our simulations the protein contained and adhered to the lipid bilayer while providing good coverage of the lipid tails. Images FIGURE 1 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 7 FIGURE 8 PMID:9370429

Phillips, J C; Wriggers, W; Li, Z; Jonas, A; Schulten, K



Switching to black rice diets modulates low-density lipoprotein oxidation and lipid measurements in rabbits.  


The effect of white and black rice consumption on lipid profile, hydroperoxides, thiobarbituric reactive substances and oxidized low-density lipoprotein (LDL) induced by hypercholesterolemia was investigated in 24 male rabbits; a purified normal diet (NC, n = 6), a high fat/cholesterol (1.0 g/100 g) diet (PC group, n = 6), a high fat/cholesterol diet with 25 g/100 g white ground rice (PCWR group, n = 6), 25 g/100 g black ground rice (PCBR group, n = 6) for 10 weeks. Blood samples were collected for lipid measurements. Results indicate that serum high-density lipoprotein-cholesterol was higher (P < 0.05) in the PCBR compared with the PC and PCWR groups. Hydroperoxides and thiobarbituric reactive substances were significantly lower (P < 0.05) in the PCBR compared with PCWR and PC groups. Cyanidin-3-glucoside (Cy-3-Glu) and peonidin-3-glucoside have been tested in vitro against copper-mediated low-density lipoprotein. Cy-3-Glu was excelled peonidin-3-glucoside by increasing the lag time of NC from 80 to 500 minutes in the presence of 2.0 ?M of Cy-3-Glu. Hierarchically, black rice rabbits group was given the best results compared with other groups. The results may be indicating to a suggested mechanism (anthocyanins protection; Cy-3-Glu) of the cardioprotective effect of black rice. PMID:21289511

Abdel-Moemin, Aly R



Estradiol replacement increases the low-density lipoprotein receptor related protein (LRP) in the mouse brain.  


Numerous epidemiology studies have shown protective effects of hormone therapy (HT) on chronic neurological diseases. We have proposed that some of the neuroprotective effects of estrogen are mediated by apolipoprotein E (apoE). Polymorphisms of receptors for apoE modify the risk for dementia. To our knowledge, no reports exist showing CNS effects of estrogen replacement on members of the low-density lipoprotein receptor family. The current study focused on the effect of estradiol-17beta (E2) replacement on protein expression of two members of the receptor family, the low-density lipoprotein receptor (LDL-r) and low-density lipoprotein receptor related protein (LRP) in ovariectomized mice. Five days of E2 replacement significantly increased LRP expression in the hippocampus, olfactory bulb and neocortex but not in cerebellum. In contrast, E2 treatment decreased LDL-r protein expression in olfactory bulb. HT modification of both apoE and LRP could have wide-spread effects on cellular function given LRP's manifold signaling functions. PMID:17346883

Cheng, Xiangying; McAsey, Mary Ellen; Li, Miao; Randall, Shari; Cady, Craig; Nathan, Britto P; Struble, Robert G




Technology Transfer Automated Retrieval System (TEKTRAN)

To test the hypothesis whether determination of high-density lipoprotein (HDL) subpopulations provides more power to predict recurrent cardiovascular disease (CVD) events (nonfatal myocardial infarction, coronary heart disease death, and stroke) than traditional risk factors in the Veterans Affairs ...


Human plasma trans-sialidase causes atherogenic modification of low density lipoprotein.  


In earlier studies we have found that incubation of low density lipoprotein (LDL) with autologous blood plasma-derived serum leads to a loss of sialic acid from lipoprotein particles. In this study we demonstrated that sialic acid removed from LDL was transferred to glycoconjugates of lipoproteins, glycoproteins and sphingolipids of human serum. This showed that human serum contained the trans-sialidase activity. Gel-filtration chromatography of human blood serum demonstrated the presence of trans-sialidase activity in lipoprotein subfractions as well as in lipoprotein-deficient serum. Trans-sialidase (about 65 kDa) was isolated from lipoprotein-deficient serum using affinity chromatography carried out with Neu5Acalpha2-8Neu5Ac-sepharose FF-6. Optimal pH values for the trans-sialidase were 3.0, 5.0 and 7.0. Calcium and magnesium ions stimulated the enzyme activity at millimolar concentrations. Isolated enzyme can remove sialic acid from LDL, IDL, VLDL, and HDL particles (in decreasing rate order). Serum trans-sialidase transferred sialic acid from glycoconjugates of plasma proteins (fetuin, transferrin) and gangliosides (GM3, GD3, GM1, GD1a, GD1b). Sialylated glycoconjugates of human blood erythrocytes also served as substrate for serum trans-sialidase. We have found that sialic acid can also be removed from N- and O-linked glycans, sialylated Le(x) and Le(a), oligosialic acids, and sphingolipid carbohydrate chains. The rate of sialic acid release decreased in the following order: alpha2,6>alpha2,3>alpha2,8. Transferred molecule of sialic acid can form alpha2,6, alpha2,3 and to a lesser degree alpha2,8 linkage with galactose, N-acetyl-galactosamine or sialic acid of acceptors. The glycoconjugates of erythrocytes, lipoprotein particles, plasma proteins, neutral sphingolipids and gangliosides may serve as acceptors of transferred sialic acid. Trans-sialidase-treated native LDL becomes desialylated and then can induce cholesteryl ester accumulation in human aortic intimal smooth muscle cells. Thus, trans-sialidase may be involved in the early stages of atherogenesis characterized by foam cell formation. PMID:11689212

Tertov, V V; Kaplun, V V; Sobenin, I A; Boytsova, E Y; Bovin, N V; Orekhov, A N



Apolipoprotein B and non-high density lipoprotein cholesterol and the risk of coronary heart disease in Chinese  

Microsoft Academic Search

The aim of our study was to compare apolipo- protein B (apoB), non-high density lipoprotein cholesterol (nonHDL-C), low density lipoprotein cholesterol (LDL-C), and other lipid markers as predictors of coronary heart dis- ease (CHD) in Chinese. Overall, 122 individuals developed CHD during a median 13.6 years of follow-up in 3,568 adult participants from a community-based cohort. The multivari- ate relative

Kuo-Liong Chien; Hsiu-Ching Hsu; Ta-Chen Su; Ming-Fong Chen; Yuan-Teh Lee; Frank B. Hu



Estimation oftheConcentration of Low-Density Lipoprotein Cholesterol inPlasma, Without UseofthePreparative Ultracentrifuge  

Microsoft Academic Search

A method for estimating the cholesterol content of the serum low-density lipoprotein fraction (Sf- 0.20)is presented. The method involves measure- ments of fasting plasma total cholesterol, tri- glyceride, and high-density lipoprotein cholesterol concentrations, none of which requires the use of the preparative ultracentrifuge. Cornparison of this suggested procedure with the more direct procedure, in which the ultracentrifuge is used, yielded

William T. Friedewald; Robert I. Levy; Donald S. Fredrickson



Single step reconstitution of multifunctional high-density lipoprotein-derived nanomaterials using microfluidics.  


High-density lipoprotein (HDL) is a natural nanoparticle that transports peripheral cholesterol to the liver. Reconstituted high-density lipoprotein (rHDL) exhibits antiatherothrombotic properties and is being considered as a natural treatment for cardiovascular diseases. Furthermore, HDL nanoparticle platforms have been created for targeted delivery of therapeutic and diagnostic agents. The current methods for HDL reconstitution involve lengthy procedures that are challenging to scale up. A central need in the synthesis of rHDL, and multifunctional nanomaterials in general, is to establish large-scale production of reproducible and homogeneous batches in a simple and efficient fashion. Here, we present a large-scale microfluidics-based manufacturing method for single-step synthesis of HDL-mimicking nanomaterials (?HDL). ?HDL is shown to have the same properties (e.g., size, morphology, bioactivity) as conventionally reconstituted HDL and native HDL. In addition, we were able to incorporate simvastatin (a hydrophobic drug) into ?HDL, as well as gold, iron oxide, quantum dot nanocrystals or fluorophores to enable its detection by computed tomography (CT), magnetic resonance imaging (MRI), or fluorescence microscopy, respectively. Our approach may contribute to effective development and optimization of lipoprotein-based nanomaterials for medical imaging and drug delivery. PMID:24079940

Kim, YongTae; Fay, Francois; Cormode, David P; Sanchez-Gaytan, Brenda L; Tang, Jun; Hennessy, Elizabeth J; Ma, Mingming; Moore, Kathryn; Farokhzad, Omid C; Fisher, Edward Allen; Mulder, Willem J M; Langer, Robert; Fayad, Zahi A



Current guidelines for high-density lipoprotein cholesterol in therapy and future directions  

PubMed Central

Many studies have suggested that a significant risk factor for atherosclerotic cardiovascular disease (ASCVD) is low high-density lipoprotein cholesterol (HDL-C). Therefore, increasing HDL-C with therapeutic agents has been considered an attractive strategy. In the prestatin era, fibrates and niacin monotherapy, which cause modest increases in HDL-C, reduced ASCVD events. Since their introduction, statins have become the cornerstone of lipoprotein therapy, the benefits of which are primarily attributed to decrease in low-density lipoprotein cholesterol. Findings from several randomized trials involving niacin or cholesteryl ester transfer protein inhibitors have challenged the concept that a quantitative elevation of plasma HDL-C will uniformly translate into ASCVD benefits. Consequently, the HDL, or more correctly, HDL-C hypothesis has become more controversial. There are no clear guidelines thus far for targeting HDL-C or HDL due to lack of solid outcomes data for HDL specific therapies. HDL-C levels are only one marker of HDL out of its several structural or functional properties. Novel approaches are ongoing in developing and assessing agents that closely mimic the structure of natural HDL or replicate its various functions, for example, reverse cholesterol transport, vasodilation, anti-inflammation, or inhibition of platelet aggregation. Potential new approaches like HDL infusions, delipidated HDL, liver X receptor agonists, Apo A-I upregulators, Apo A mimetics, and gene therapy are in early phase trials. This review will outline current therapies and describe future directions for HDL therapeutics. PMID:24748800

Subedi, Bishnu H; Joshi, Parag H; Jones, Steven R; Martin, Seth S; Blaha, Michael J; Michos, Erin D



Single Step Reconstitution of Multifunctional High-Density Lipoprotein-Derived Nanomaterials Using Microfluidics  

PubMed Central

High-density lipoprotein (HDL) is a natural nanoparticle that transports peripheral cholesterol to the liver. Reconstituted high-density lipoprotein (rHDL) exhibits antiatherothrombotic properties and is being considered as a natural treatment for cardiovascular diseases. Furthermore, HDL nanoparticle platforms have been created for targeted delivery of therapeutic and diagnostic agents. The current methods for HDL reconstitution involve lengthy procedures that are challenging to scale up. A central need in the synthesis of rHDL, and multifunctional nanomaterials in general, is to establish large-scale production of reproducible and homogeneous batches in a simple and efficient fashion. Here, we present a large-scale microfluidics-based manufacturing method for single-step synthesis of HDL-mimicking nanomaterials (µHDL). µHDL is shown to have the same properties (e.g., size, morphology, bioactivity) as conventionally reconstituted HDL and native HDL. In addition, we were able to incorporate simvastatin (a hydrophobic drug) into µHDL, as well as gold, iron oxide, quantum dot nanocrystals or fluorophores to enable its detection by computed tomography (CT), magnetic resonance imaging (MRI), or fluorescence microscopy, respectively. Our approach may contribute to effective development and optimization of lipoprotein-based nanomaterials for medical imaging and drug delivery. PMID:24079940

Kim, YongTae; Fay, Francois; Cormode, David P.; Sanchez-Gaytan, Brenda L.; Tang, Jun; Hennessy, Elizabeth J.; Ma, Mingming; Moore, Kathryn; Farokhzad, Omid C.; Fisher, Edward Allen; Mulder, Willem J. M.; Langer, Robert; Fayad, Zahi A.



Phenotypes and Genotypes of High Density Lipoprotein Cholesterol in Exceptional Longevity  

PubMed Central

A change in the lipoprotein profile is a metabolic hallmark of aging and has been the target for modern medical developments. Although pharmaceutical interventions aimed at lipid lowering substantially decrease the risk of cardiovascular disease, they have much less impact on mortality and longevity. Moreover, they have not affected death from other age-related diseases. In this review we focus on high density lipoprotein (HDL) cholesterol, the levels of which are either elevated or do not decrease as would be expected with aging in centenarians, and which are associated with lower prevalence of numerous age-related diseases; thereby, suggesting a potential HDL-mediated mechanism for extended survival. We also provide an update on the progress of identifying longevity-mediating lipid genes, describe approaches to discover longevity genes, and discuss possible limitations. Implicating lipid genes in exceptional longevity may lead to drug therapies that prevent several age-related diseases, with such efforts already on the way. PMID:24350928

Milman, Sofiya; Atzmon, Gil; Crandall, Jill; Barzilai, Nir



Ascorbic acid protects lipids in human plasma and low-density lipoprotein against oxidative damage  

SciTech Connect

The authors exposed human blood plasma and low-density lipoprotein (LDL) to many different oxidative challenges and followed the temporal consumption of endogenous antioxidants in relation to the initiation of oxidative damage. Under all types of oxidizing conditions, ascorbic acid completely protects lipids in plasma and LDL against detectable peroxidative damage as assessed by a specific and highly sensitive assay for lipid peroxidation. Ascorbic acid proved to be superior to the other water-soluble plasma antioxidants bilirubin, uric acid, and protein thiols as well as to the lipoprotein-associated antioxidants alpha-tocopherol, ubiquinol-10, lycopene, and beta-carotene. Although these antioxidants can lower the rate of detectable lipid peroxidation, they are not able to prevent its initiation. Only ascorbic acid is reactive enough to effectively intercept oxidants in the aqueous phase before they can attack and cause detectable oxidative damage to lipids.

Frei, B. (Department of Nutrition, Harvard School of Public Health, Boston, MA (Unites States))



The low-density lipoprotein receptor gene family: a cellular Swiss army knife?  


The low-density lipoprotein receptor gene family is an evolutionarily conserved group of cell-surface receptors produced by mammals and other organisms. Initially thought to be endocytic receptors that mediate the uptake of lipoproteins, recent findings have shown that these receptors have other roles in a range of cellular processes. Among other activities, members of this family act as signal transducers in neuronal migration processes, regulate synaptic plasticity or control vitamin homeostasis. Such multifunctionality is achieved by interaction with diverse cell-surface proteins including glycolipid-anchored receptors, G-protein-coupled receptors and ion channels. Here, we review the molecular interactions of this protein family with other cell-surface proteins that provide specificity and versatility - a versatility that may be reminiscent of a cellular Swiss army knife. PMID:12074887

Nykjaer, Anders; Willnow, Thomas E



Current status and future directions in lipid management: emphasizing low-density lipoproteins, high-density lipoproteins, and triglycerides as targets for therapy.  


Current lipid management guidelines are focused on decreasing low-density lipoprotein (LDL-C) levels as the primary target for reducing coronary heart disease (CHD) risk. Yet, many recent studies suggest that low levels of high-density lipoprotein (HDL-C) are a major independent risk factor for cardiovascular diseases. According to several clinical trials, a 1% increase in HDL-C is associated with a 0.7%-3% decrease in CHD events. The direct link between high levels of triglycerides (TG) and CHD, on the other hand, is less well defined. A large reduction in TG is needed to show a difference in CHD events, especially in men. Evidence for a shift in lipid management toward targeting both LDL-C and HDL-C as primary targets for therapy is presented. Currently, the 3-hydroxy-3-methylgutaryl coenzyme A reductase inhibitors (HMG-CoA reductase inhibitors) have proven to significantly decrease LDL-C levels, reduce CHD morbidity/mortality and improve overall survival. However, improvement of survival with statins may be due to other pleiotropic effects beyond LDL-C lowering. Fibric acid derivatives and niacin are primarily used to increase HDL-C levels, although with side effects. Future therapies targeting HDL-C may have profound results on reducing CHD morbidity and mortality. This article highlights existing and future targets in lipid management and is based on available clinical data. There is an urgent need for new treatments using a combination of drugs targeting both LDL-C and HDL-C. Such treatments are expected to have a superior outcome for dyslipidemia therapy, along with TG management. PMID:20234782

Lin, Yun; Mousa, Shaymaa S; Elshourbagy, Nabil; Mousa, Shaker A



The role of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) in comparison with whole egg yolk for sperm cryopreservation in rhesus monkeys  

PubMed Central

Low-density lipoprotein (LDL) extracted from hen egg yolk has recently been considered to be superior to whole egg yolk in sperm cryopreservation of various animal species. Meanwhile, there was a notion that high-density lipoprotein (HDL) in egg yolk may have a negative effect on post-thaw survival. The role of LDL and HDL in sperm cryopreservation of rhesus monkeys has not been explored. The present study evaluates their effect in comparison with egg yolk with or without the addition of permeable cryoprotectant (glycerol) on sperm cryopreservation of rhesus macaques. In addition, various additives intended to change the lipid composition of LDL–sperm membrane complex have also been tested for their effectiveness in preserving post-thaw viability. Our findings indicated that LDL is the main component in egg yolk that is responsible for its protective role for sperm cryopreservation in rhesus monkeys. Regardless of the presence or absence of glycerol, the protective role of LDL is similar to that of egg yolk and we did not observe any superiority in post-thaw survival with LDL when compared to egg yolk. Modifying the lipid composition of LDL–sperm membrane complex with the addition of cholesterol, cholesterol loaded cyclodextrin and phosphatidylcholine also did not yield any improvements in post-thaw survival; while addition of methyl-?-cyclodextrin reduced post-thaw motility. HDL plays a neutral role in sperm cryopreservation of rhesus monkeys. The present study suggests that egg yolk may still hold advantages when compared with LDL as effective components in extenders for sperm cryopreservation in rhesus monkeys. PMID:21423197

Dong, Qiao-Xiang; Rodenburg, Sarah E; Hill, Dana; VandeVoort, Catherine A



High-density lipoprotein cholesterol as a predictor of clinical outcomes in patients achieving low-density lipoprotein cholesterol targets with statins after percutaneous coronary intervention  

PubMed Central

Background A low level of high-density lipoprotein cholesterol (HDL-C) is strongly associated with cardiovascular events. However, the significance of HDL-C after statin therapy on the outcome of patients who have undergone percutaneous coronary intervention (PCI) with drug eluting stents (DES) is unclear. Objectives To investigate the significance of HDL-C after statin therapy on cardiovascular events in patients with coronary artery disease after DES implantation. Methods Patients who underwent PCI with DES from January 2004 to December 2009 were prospectively enrolled. The follow-up lipid panel of 2693 patients (median lab follow-up duration 225?days) who had continued using statins after PCI and who attained low-density lipoprotein cholesterol (LDL-C) <100?mg/dl was analysed. Major adverse cardiac events (MACE), including all-cause death, non-fatal myocardial infarction, and target vessel revascularisation according to follow-up HDL-C level (40?mg/dl for men or 50?mg/dl for women) were compared with the use of propensity scores matching. Results Median follow-up duration was 832?days. 1585 (58.9%) patients had low follow-up HDL-C and 1108 had high follow-up HDL-C. The low follow-up HDL-C group had significantly higher rates of MACE. Low follow-up HDL-C was a significant independent predictor of MACE (adjusted HR 1.404, 95% CI 1.111 to 1.774, p=0.004). In further analysis with propensity scores matching, overall findings were consistent. Conclusions Raising HDL-C levels may be a subsequent goal after achieving target LDL-C levels in patients with DES implantation. PMID:21665885

Seo, Suk Min; Choo, Eun-Ho; Koh, Yoon-Seok; Park, Mahn Won; Shin, Dong Il; Choi, Yoon Seok; Park, Hun-Jun; Kim, Dong Bin; Her, Sung Ho; Lee, Jong Min; Park, Chul Soo; Kim, Pum-Joon; Moon, Keon Woong; Chang, Kiyuk; Kim, Hee Yeol; Yoo, Ki Dong; Jeon, Doo Soo; Chung, Wook Sung; Park, Yong Gyu



Organization of phosphatidylcholine and sphingomyelin in the surface monolayer of low density lipoprotein and lipoprotein(a) as determined by time-resolved fluorometry.  


Fluorescent analogs of phosphatidylcholine (PC) and sphingomyelin (SM) labeled with diphenylhexatrienylpropionic acid (DPH) were prepared and incorporated into the surface layer of human low density lipoprotein (LDL) and lipoprotein(a) (Lp(a)). Fluorescence anisotropy measurements of DPH-PC and DPH-SM in both lipoprotein classes were carried out at different temperatures ranging from 20 to 37 degrees C. DPH-PC as well as DPH-SM were shown to reside in more rigid domains in Lp(a) than in LDL according to higher anisotropy values in Lp(a). In both LDL and Lp(a), DPH-PC experienced a more rigid environment than DPH-SM, suggesting different environments of PC and SM in the surface shell of the lipoproteins. Fluorescence lifetimes of the labeled lipoproteins were determined by phase and modulation fluorometry. We found bimodal Lorentzian distributions for the decay times of DPH-PC and DPH-SM in LDL and Lp(a). Lifetime distribution centers for labeled lipids were very similar except for DPH-PC in Lp(a) which was shifted to longer lifetimes, suggesting a less polar environment of PC in Lp(a) than in LDL. The distributional width of DPH-PC in Lp(a) was broader than in LDL. Accordingly, phosphatidylcholine must be localized in a more homogeneous environment in LDL as compared with Lp(a). On the other hand, no difference in distributional widths was observed for DPH-SM in both lipoproteins, showing that SM organization in Lp(a) is unaffected by apo(a). From the obtained fluorescence data we propose that apoproteins discriminate between the choline phospholipids and preferentially associate with phosphatidylcholine. This effect is enhanced in Lp(a) due to the presence of apolipoprotein(a). PMID:1447171

Sommer, A; Prenner, E; Gorges, R; Stütz, H; Grillhofer, H; Kostner, G M; Paltauf, F; Hermetter, A



Association of High-density Lipoprotein Cholesterol With Improvement of Endothelial Dysfunction Recovery in Renovascular Disease.  


Introduction. This study was aimed to assess the ratio of total cholesterol (TC) to high-density density lipoprotein cholesterol (HDLC) and plasma nitrate levels in patients with ischemic nephropathy receiving statins and niacin extended release (NER). Materials and Methods. Kidney disease patients with a history of at least 5 year of diabetes mellitus or 10 year of hypertension were screened by renal artery Doppler ultrasonography. Participants were randomly assigned into two groups to receive atorvastatin, 20 mg/d, with and without NER, 500 mg/d, for 16 weeks. Serum levels of lipid profile, creatinine, and nitrate were compared before and after the study. Results. Fifty-four patients received the statin and 51 received statin-NER combination. Both statin and statin-NER groups demonstrated significant decreases in plasma levels of TC and low-density lipoprotein cholesterol. Triglyceride and very low-density lipoprotein cholesterol were significantly lowered only with statin-NER combination. The increase in HDLC level was found in both groups, but significant only with statin-NER combination therapy (P < .001). Atorvastatin combined with NER reduced TC/HDLC ratio almost double as compared with that of atorvastatin alone (102% and 36.6% reduction, respectively). A similar pattern was observed for nitrate levels (33% and 65%, respectively). Conclusions. These findings indicated that a reduction in TC/HDLC ratio improves endothelial function in renovascular disease and use of NER in combination with atorvastatin may provide better outcomes. This could be helpful in attenuating further vascular damage and associated systemic complications.   PMID:25599735

Yasmeen, Ghazala; Dawani, Manohar Lal; Mahboob, Tabassum



Regulation of low-density lipoprotein receptors in the human hepatoma cell line Hep G2.  


The human hepatoma cell line Hep G2 can be maintained in continuous culture and secretes numerous plasma proteins and lipoproteins into the medium. To better characterize cholesterol homeostasis in these cells we have examined the binding, internalization and degradation of [125I]LDL by cultured Hep G2 cells. Hep G2 cells express high-affinity low-density lipoprotein (LDL) receptors which facilitate the binding, internalization and degradation of [125I]LDL; these receptors can be induced by growth in LDL-depleted medium and repressed by further incubation in medium supplemented with LDL. The degradation of [125I]LDL by derepressed Hep G2 cells was inhibited by greater than 90% by monensin. Incubation of Hep G2 cells in the presence of increasing concentrations of LDL also inhibited cholesterol biosynthesis. Our results indicate that Hep G2 cells possess high affinity LDL receptors which are subject to metabolic regulation and suggest that this cell line affords a valuable model to further examine cholesterol and lipoprotein metabolism in human liver cells. PMID:6094224

Illingworth, D D; Lindsey, S; Hagemenas, F C



The Role of the High-Density Lipoprotein Receptor SR-BI in the Lipid Metabolism of Endocrine and Other Tissues  

Microsoft Academic Search

Because cholesterol is a precursor for the synthesis of steroid hormones, steroidogenic tissues have evolved multiple path- ways to ensure adequate supplies of cholesterol. These in- clude synthesis, storage as cholesteryl esters, and import from lipoproteins. In addition to endocytosis via members of the low-density lipoprotein receptor superfamily, steroidogenic cells acquire cholesterol from lipoproteins by selective lipid uptake. This pathway,




Characterization of low density lipoprotein receptor ligand interactions by fluorescence resonance energy transfer.  


The low density lipoprotein receptor (LDLR) is the prototype of a family of cell surface receptors involved in a wide range of biological processes. A soluble low density lipoprotein receptor (sLDLR) and a tryptophan (Trp)-deficient variant human apolipoprotein E3 (apoE3) N-terminal domain (NT) were used in binding studies. The sole cysteine in apoE3-NT was covalently modified with an extrinsic fluorescence probe, N-(iodoacetyl)-N'-(5-sulfo-1-napthyl)ethylenediamine (AEDANS), and the protein was complexed with lipid. Incubation of sLDLR with AEDANS-Trp-null apoE3-NT dimyristoylphosphatidylcholine (DMPC) disks, but not lipid-free AEDANS-apoE, induced an enhancement in AEDANS fluorescence emission intensity (excitation, 280 nm) consistent with intermolecular energy transfer from excited Trp in sLDLR to receptor-bound apoE. Ligand binding to sLDLR required calcium and was saturable. In competition binding assays, unlabeled apoE3-NT DMPC inhibited AEDANS-apoE DMPC binding to sLDLR more effectively than low density lipoprotein. Fluorescence changes in this system reflected pH-dependent ligand binding and release from sLDLR consistent with models derived from the X-ray crystal structure of the receptor at endosomal pH. Intermolecular energy transfer from excited Trp in LDLR family members to fluorescently tagged ligands represents a sensitive and convenient assay for the characterization of the myriad molecular interactions ascribed to this family of receptor. PMID:16467279

Yamamoto, Taichi; Lamoureux, Johanne; Ryan, Robert O



Dusty punch cards and an eternal enigma: high-density lipoproteins and atherosclerosis.  


Epidemiological, clinical, and experimental evidence has accumulated during the last decades suggesting that high-density lipoproteins (HDLs) may protect from atherosclerosis and its clinical consequences. However, more than 55 years after the first description of the link between HDL and heart attacks, many facets of the biochemistry, function, and clinical significance of HDL remain enigmatic. This applies particularly to the completely unexpected results that became available from some recent clinical trials of nicotinic acid and of inhibitors of cholesteryl ester transfer protein (CETP). The concept that raising HDL cholesterol by pharmacological means would decrease the risk of vascular disease has therefore been challenged. PMID:24691706

Kleber, Marcus E; Grammer, Tanja B; Kassner, Ursula; Silbernagel, Günther; März, Winfried



Synthetic high-density lipoprotein-like nanoparticles for cancer therapy.  


High-density lipoproteins (HDLs) are a diverse group of natural nanoparticles that are most well known for their role in cholesterol transport. However, HDLs have diverse functions that provide significant opportunities for cancer therapy. Presented is a focused review of the ways that synthetic versions of HDL have been used as targeted therapies for cancer, and as vehicles for the delivery of diverse therapeutic cargo to cancer cells. As such, synthetic HDLs are likely to play a central role in the development of next-generation cancer therapies. PMID:25487833

Foit, Linda; Giles, Francis J; Gordon, Leo I; Thaxton, Colby Shad



Synthetic Nano-Low Density Lipoprotein as Targeted Drug DeliveryVehicle for Glioblastoma Multiforme  

SciTech Connect

This paper discribes a synthetic low density lipoprotein(LDL) made by complexing a 29 amino acid that consists of a lipid bindingdomain and the LDL receptor binding domain with a lipid microemulsion.The nano-LDL particles were intermdiate in size between LDL and HDL andbound to LDL receptors on GBM brain tumor cells. Synthetic nano-LDLuptake by GBM cells was LDL receptor specific and dependent on cellreceptor number. It is suggested that these synthetic particles can serveas a delivery vehicle for hydophobic anti-tumor drugs by targeting theLDL receptor.

Nikanjam, Mina; Blakely, Eleanor A.; Bjornstad, Kathleen A.; Shu,Xiao; Budinger, Thomas F.; Forte, Trudy M.



[Comparison between treatments of severe forms of familial hypercholesterolemia by total plasma exchange and selective removal of low density lipoproteins (LDLapheresis)].  


A plasma exchange program for familial hypercholesterolaemia was started in 1982. Ten patients aged from 7 to 58 years were progressively included: 3 had an heterozygous form of the disease with ischaemic heart disease; 3 had an homozygous form with defective low density lipoprotein receptor activity, 4 had a receptor-negative homozygous familial hypercholesterolaemia and had previously undergone portacaval shunt. During total plasma exchange against human albumin (470 sessions in 9 patients) low density lipoprotein cholesterol values, but also high density lipoprotein cholesterol values, decreased by 40 per cent. More recently, 5 patients had selective low density lipoprotein absorption on dextran sulfate column (Liposorber); 90 exchanges were performed. High density lipoprotein cholesterol values decreased by 55 per cent and high density lipoprotein cholesterol values by only 27 per cent. The patients' attitude to treatment was excellent, with less fatigue and better compliance. PMID:2973030

Dairou, F; Rottembourg, J; de Gennes, J L; Assogba, U; Bruckert, E; Jacobs, C; Truffert, J



The secondary structure of apolipoprotein?A-I on 9.6-nm reconstituted high-density lipoprotein determined by EPR spectroscopy  

PubMed Central

Apolipoprotein?A-I (ApoA-I) is the major protein component of high-density lipoprotein (HDL), and is critical for maintenance of cholesterol homeostasis. During reverse cholesterol transport, HDL transitions between an array of subclasses, differing in size and composition. This process requires ApoA-I to adapt to changes in the shape of the HDL particle, transiting from an apolipoprotein to a myriad of HDL subclass-specific conformations. Changes in ApoA-I structure cause alterations in HDL-specific enzyme and receptor-binding properties, and thereby direct the HDL particle through the reverse cholesterol transport pathway. In this study, we used site-directed spin label spectroscopy to examine the conformational details of the ApoA-I central domain on HDL. The motional dynamics and accessibility to hydrophobic/hydrophilic relaxation agents of ApoA-I residues?99–163 on 9.6-nm reconstituted HDL was analyzed by EPR. In previous analyses, we examined residues?6–98 and 164–238 (of ApoA-I's 243 residues), and combining these findings with the current results, we have generated a full-length map of the backbone structure of reconstituted HDL-associated ApoA-I. Remarkably, given that the majority of ApoA-I's length is composed of amphipathic helices, we have identified nonhelical residues, specifically the presence of a ?-strand (residues?149–157). The significance of these nonhelical residues is discussed, along with the other features, in the context of ApoA-I function in contrast to recent models derived by other methods. PMID:23668303

Oda, Michael N; Budamagunta, Madhu S; Borja, Mark S; Petrlova, Jitka; Voss, John C; Lagerstedt, Jens O



Effects of oxidized low density lipoproteins on arachidonic acid metabolism in smooth muscle cells.  


The role of oxidized plasma lipoproteins in modifying arachidonic acid (AA) metabolism was studied in smooth muscle cells (SMC). Very low density lipoproteins (VLDL), unoxidized low density lipoproteins (LDLBHT) isolated with butylated hydroxytoluene (BHT), and oxidized LDL (LDLOXID) were separated from human serum. Thiobarbituric acid reactant (TBAR) levels were adjusted by saline incubations. Prostanoids in guinea pig SMC cultures were measured either by radioimmunoassay (RIA) or the isolation by high performance liquid chromatography (HPLC) of labeled prostanoids from SMC prelabeled with [14C]AA. Cell morphology and viability were studied by staining with Giemsa, nile red, and propidium iodide. VLDL and LDLBHT had little effect on prostanoid synthesis. Low-TBAR-LDLOXID enhanced total prostanoid levels and diminished the release of labeled prostanoids. Similar effects were found with exogenous free AA (unlabeled). Low-TBAR-LDLOXID did not affect the release of endogenous phospholipid AA as free AA. Synergism occurred between LDLOXID and exogenous free AA in prostanoid synthesis. Low-TBAR-LDLOXID evidently enhanced prostanoid levels in SMC both by supplying AA and by stimulating cyclooxygenase. High-TBAR-LDLOXID blocked prostanoid synthesis and enhanced cell death but time and pulse-recovery experiments showed that these effects were unrelated. High-TBAR-LDLOXID stimulated prostanoid synthesis when BHT was added to the incubation media. High-TBAR-LDLOXID also caused massive free AA release and the formation of many nonprostanoid derivatives. High-TBAR-LDLOXID evidently diminished overall prostanoid levels in SMC by inhibiting cyclooxygenase and at the same time stimulating AA release and the formation of other AA derivatives. PMID:2351866

Zhang, H F; Davis, W B; Chen, X S; Jones, K H; Whisler, R L; Cornwell, D G



The effects of monensin on secretion of very-low-density lipoprotein and metabolism of asialofetuin by cultured rat hepatocytes.  

PubMed Central

Primary cultures of rat hepatocytes were used to study secretion of very-low-density lipoproteins and metabolism of asialofetuin. The ionophore monensin inhibited both secretion of very-low-density lipoproteins and binding and degradation of asialofetuin in a concentration-dependent manner. Secretion as well as receptor binding were markedly decreased after 15 min treatment with monensin. The inhibitory effect of the ionophore was fully reversible, and no effect on protein synthesis was observed at concentrations up to 50 microM. The secretion of apoproteins (B-small, B-large and E) and that of albumin were inhibited to the same extent as was triacylglycerol secretion. Secretion of very-low-density lipoproteins was more sensitive to low concentrations of monensin than was the metabolism of asialofetuin. Maximum inhibition of very-low-density-lipoprotein secretion was obtained at 5-10 microM-monensin, whereas 25 microM was required to obtain maximum inhibition of binding and degradation of asialofetuin. The number of surface receptors for asialofetuin decreased to about half when the cells were exposed to 25 microM-monensin. It is possible that monensin inhibits endo- and exo-cytosis via a similar mechanism, e.g. by disturbing proton gradients. Since secretion of very-low-density lipoproteins was more sensitive to low concentrations of monensin, it is likely that monensin independently inhibits endocytic and secretory functions in cultured hepatocytes. PMID:2408603

Rustan, A C; Nossen, J O; Berg, T; Drevon, C A



Proteomic Characterization of Human Plasma High Density Lipoprotein Fractionated by Gel Filtration Chromatography  

PubMed Central

Plasma levels of high density lipoprotein cholesterol (HDL-C) are inversely proportional to the incidence of cardiovascular disease. Recent applications of modern proteomic technologies have identified upward of 50 distinct proteins associated with HDL particles with many of these newly discovered proteins implicating HDL in nonlipid transport processes including complement activation, acute phase response and innate immunity. However, almost all MS-based proteomic studies on HDL to date have utilized density gradient ultracentrifugation techniques for HDL isolation prior to analysis. These involve high shear forces and salt concentrations that can disrupt HDL protein interactions and alter particle function. Here, we used high-resolution size exclusion chromatography to fractionate normal human plasma to 17 phospholipid-containing subfractions. Then, using a phospholipid binding resin, we identified proteins that associate with lipoproteins of various sizes by electrospray ionization mass spectrometry. We identified 14 new phospholipid-associated proteins that migrate with traditionally defined HDL, several of which further support roles for HDL in complement regulation and protease inhibition. The increased fractionation inherent to this method allowed us to visualize HDL protein distribution across particle size with unprecedented resolution. The observed heterogeneity across subfractions suggests the presence of HDL particle subpopulations each with distinct protein components that may prove to impart distinct physiological functions. PMID:20718489

Gordon, Scott M.; Deng, Jingyuan; Lu, L. Jason; Davidson, W. Sean



Low Density Lipoprotein-Containing Circulating Immune Complexes: Role in Atherosclerosis and Diagnostic Value  

PubMed Central

It has been suggested that low density lipoprotein-containing circulating immune complexes (LDL-CIC) play a role in atherogenesis and are involved in the formation of early atherosclerotic lesion. These complexes, as well as anti-LDL autoantibodies, have been found in the blood and in the atherosclerotic lesions of patients with different cardiovascular diseases, as well as in the blood of animals with experimental atherosclerosis. It can be suggested that the presence of anti-LDL antibodies in the blood is a result of immune response induced by lipoprotein modification. LDL-CIC differs from native LDL in many aspects. It has much lower sialic acid content, smaller diameter, and higher density and is more electronegative than native LDL. Fraction of LDL-CICs is fundamental to the serum atherogenicity manifested at the cellular level. LDL-CIC, unlike native LDL, is able to induce intracellular accumulation of neutral lipids, especially esterified cholesterol, in cells cultured from uninvolved human aortic intima and in macrophage cultures. After removal of LDL-CIC, the CHD patient's sera lose their atherogenic properties. Titer of LDL-CIC in blood serum significantly correlates with progression of atherosclerosis in human in vivo and has the highest diagnostic value among other measured serum lipid parameters. Elevated CIC-cholesterol might well be a possible risk factor of coronary atherosclerosis. PMID:25054132

Sobenin, Igor A.; Salonen, Jukka T.; Zhelankin, Andrey V.; Melnichenko, Alexandra A.; Kaikkonen, Jari; Bobryshev, Yuri V.; Orekhov, Alexander N.



Lowering low-density lipoprotein cholesterol levels in patients with type 2 diabetes mellitus  

PubMed Central

Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia, insulin resistance, and/or progressive loss of ?-cell function. T2DM patients are at increased risk of micro- and macrovascular disease, and are often considered as representing an atherosclerotic coronary heart disease (CHD) risk equivalent. Interventions directed at glucose and lipid level control in T2DM patients may reduce micro- and macrovascular disease. The optimal T2DM agent is one that lowers glucose levels with limited risk for hypoglycemia, and with no clinical trial evidence of worsening CHD risk. Lipid-altering drugs should preferably reduce low-density lipoprotein cholesterol and apolipoprotein B (apo B) and have evidence that the mechanism of action reduces CHD risk. Statins reduce low-density lipoprotein cholesterol and apo B and have evidence of improving CHD outcomes, and are thus first-line therapy for the treatment of hypercholesterolemia. In patients who do not achieve optimal lipid levels with statin therapy, or who are intolerant to statin therapy, add-on therapy or alternative therapies may be indicated. Additional available agents to treat hypercholesterolemic patients with T2DM include bile acid sequestrants, fibrates, niacin, and ezetimibe. This review discusses the use of these alternative agents to treat hypercholesterolemia in patients with T2DM, either as monotherapy or in combination with statin therapy. PMID:25045281

Bays, Harold E



Low-density lipoprotein-mimicking nanoparticles for tumor-targeted theranostic applications.  


This study introduces multifunctional lipid nanoparticles (LNPs), mimicking the structure and compositions of low-density lipoproteins, for the tumor-targeted co-delivery of anti-cancer drugs and superparamagnetic nanocrystals. Paclitaxel (4.7 wt%) and iron oxide nanocrystals (6.8 wt%, 11 nm in diameter) are co-encapsulated within folate-functionalized LNPs, which contain a cluster of nanocrystals with an overall diameter of about 170 nm and a zeta potential of about -40 mV. The folate-functionalized LNPs enable the targeted detection of MCF-7, human breast adenocarcinoma expressing folate receptors, in T2 -weighted magnetic resonance images as well as the efficient intracellular delivery of paclitaxel. Paclitaxel-free LNPs show no significant cytotoxicity up to 0.2 mg mL(-1) , indicating the excellent biocompatibility of the LNPs for intracellular drug delivery applications. The targeted anti-tumor activities of the LNPs in a mouse tumor model suggest that the low-density lipoprotein-mimetic LNPs can be an effective theranostic platform with excellent biocompatibility for the tumor-targeted co-delivery of various anti-cancer agents. PMID:25137631

Lee, Jeong Yu; Kim, Jin-Ho; Bae, Ki Hyun; Oh, Mi Hwa; Kim, Youngwook; Kim, Jee Seon; Park, Tae Gwan; Park, Keunchil; Lee, Jung Hee; Nam, Yoon Sung



Low-density lipoprotein apheresis in the treatment of two patients with coronary heart disease and extremely elevated lipoprotein (a) levels.  


Hyperlipidemia and elevated lipoprotein (a) (Lp[a]) levels have been linked to the development and progression of premature atherosclerosis. Our study concerned 2 white male patients (aged 36 and 42 years) with heterozygous familial hypercholesterolemia and extremely elevated Lp(a) concentrations that were resistant to diet regimens and lipid-lowering drugs. The patients were treated with low-density lipoprotein (LDL) apheresis for 59 months (Liposorber system, Kaneka, Japan) and 19 months (immunoadsorption system, special Lp(a) columns; Lipopak; Pocard, Russia), respectively. The concentration of Lp(a) decreased on average by 50%, total cholesterol by 27%, LDL cholesterol by 41%, triglycerides by 43%, and fibrinogen by 16%. High-density lipoprotein (HDL) cholesterol increased by approximately 4%. Before treatment with LDL apheresis, each patient had suffered 3 myocardial infarctions, and had had 4 and 6 coronary angiographies with 2 and 4 percutaneous transluminal angioplasties (PTCAs), respectively. Since treatment with LDL apheresis, no myocardial infarctions or cardiac complaints were observed. In the course of treatment, both patients reported an increased performance. Available data suggest that LDL apheresis may be effective in the treatment of patients, the only risk factor for premature atherosclerosis being extremely elevated Lp(a) concentrations. PMID:9139621

Bambauer, R; Schiel, R; Keller, H E; Klinkmann, J; Latza, R



A Potential Neuroprotective Role of Apolipoprotein E-containing Lipoproteins through Low Density Lipoprotein Receptor-related Protein 1 in Normal Tension Glaucoma*  

PubMed Central

Glaucoma is an optic neuropathy and the second major cause of blindness worldwide next to cataracts. The protection from retinal ganglion cell (RGC) loss, one of the main characteristics of glaucoma, would be a straightforward treatment for this disorder. However, the clinical application of neuroprotection has not, so far, been successful. Here, we report that apolipoprotein E-containing lipoproteins (E-LPs) protect primary cultured RGCs from Ca2+-dependent, and mitochondrion-mediated, apoptosis induced by glutamate. Binding of E-LPs to the low density lipoprotein receptor-related protein 1 recruited the N-methyl-d-aspartate receptor, blocked intracellular Ca2+ elevation, and inactivated glycogen synthase kinase 3?, thereby inhibiting apoptosis. When compared with contralateral eyes treated with phosphate-buffered saline, intravitreal administration of E-LPs protected against RGC loss in glutamate aspartate transporter-deficient mice, a model of normal tension glaucoma that causes glaucomatous optic neuropathy without elevation of intraocular pressure. Although the presence of ?2-macroglobulin, another ligand of the low density lipoprotein receptor-related protein 1, interfered with the neuroprotective effect of E-LPs against glutamate-induced neurotoxicity, the addition of E-LPs overcame the inhibitory effect of ?2-macroglobulin. These findings may provide a potential therapeutic strategy for normal tension glaucoma by an LRP1-mediated pathway. PMID:22674573

Hayashi, Hideki; Eguchi, Yuko; Fukuchi-Nakaishi, Yuko; Takeya, Motohiro; Nakagata, Naomi; Tanaka, Kohichi; Vance, Jean E.; Tanihara, Hidenobu



A potential neuroprotective role of apolipoprotein E-containing lipoproteins through low density lipoprotein receptor-related protein 1 in normal tension glaucoma.  


Glaucoma is an optic neuropathy and the second major cause of blindness worldwide next to cataracts. The protection from retinal ganglion cell (RGC) loss, one of the main characteristics of glaucoma, would be a straightforward treatment for this disorder. However, the clinical application of neuroprotection has not, so far, been successful. Here, we report that apolipoprotein E-containing lipoproteins (E-LPs) protect primary cultured RGCs from Ca(2+)-dependent, and mitochondrion-mediated, apoptosis induced by glutamate. Binding of E-LPs to the low density lipoprotein receptor-related protein 1 recruited the N-methyl-d-aspartate receptor, blocked intracellular Ca(2+) elevation, and inactivated glycogen synthase kinase 3?, thereby inhibiting apoptosis. When compared with contralateral eyes treated with phosphate-buffered saline, intravitreal administration of E-LPs protected against RGC loss in glutamate aspartate transporter-deficient mice, a model of normal tension glaucoma that causes glaucomatous optic neuropathy without elevation of intraocular pressure. Although the presence of ?2-macroglobulin, another ligand of the low density lipoprotein receptor-related protein 1, interfered with the neuroprotective effect of E-LPs against glutamate-induced neurotoxicity, the addition of E-LPs overcame the inhibitory effect of ?2-macroglobulin. These findings may provide a potential therapeutic strategy for normal tension glaucoma by an LRP1-mediated pathway. PMID:22674573

Hayashi, Hideki; Eguchi, Yuko; Fukuchi-Nakaishi, Yuko; Takeya, Motohiro; Nakagata, Naomi; Tanaka, Kohichi; Vance, Jean E; Tanihara, Hidenobu



Passage of Low-density Lipoproteins Through Bruch’s Membrane and Choroid  

PubMed Central

Plasma lipoproteins are thought to transport cholesterol, vitamins and carotenoids to the retinal pigment epithelium (RPE) for ultimate use by the photoreceptors. However, to reach the RPE, these lipoprotein particles must cross Bruch’s membrane. We examined the reflection coefficient of Bruch’s membrane (BrM) to low-density lipoprotein (LDL). Bruch’s membrane and choroid were removed from 47 bovine eyes. Specimens were placed in a Ussing chamber and perfused with phosphate-buffered saline (PBS) with (31 specimens) or without (16 specimens) fluorescent low-density lipoproteins (DiI-LDL). The hydraulic conductivity of the tissue was determined for both calf and cow eyes. In the perfusions with DiI-LDL, the fluorescence intensity emitted by DiI-LDL in the efflux was measured and the reflection coefficient of BrM/choroid preparations to DiI-LDL determined. Leakage tests were done to confirm tissue integrity. Several specimens were examined using scanning electron microscopy (SEM) to examine tissue integrity before and after perfusion. Leak testing confirmed that BrM was intact both before and after perfusion. The average hydraulic conductivity of BrM/choroid perfusion of calf eyes with PBS alone was 1.42 ± 0.55 ×10?9 m/s/Pa (mean ± SD, n = 11). The average hydraulic conductivity of the cow eyes was 4.94 ± 1.48 ×10?10 m/s/Pa (n = 5), nearly a 3-fold decrease with age. While the flow rate remained constant during the PBS perfusions, it decreased as a function of time during perfusion with DiI-LDLs. Our major finding was of fluorescence in the effluent collected in all perfusions with DiI-LDLs, demonstrating passage of LDL through the tissue. The average reflection coefficient of calf BrM/choroid preparations to DiI-LDL was 0.58 ± 0.25 (n = 23); a similar distribution of reflection coefficients was seen in tissue from cow eyes (0.51 ± 0.33, n = 8). Our data suggested that the DiI-LDL was modestly hindered and/or captured by the tissue. This might explain the progressive decrease of hydraulic conductivity with continued perfusion of DiI-LDL. PMID:22063729

Cankova, Zdravka; Huang, Jiahn-Dar; Kruth, Howard S.; Johnson, Mark



Nicotinic acid decreases apolipoprotein B100-containing lipoprotein levels by reducing hepatic very low density lipoprotein secretion through a possible diacylglycerol acyltransferase 2 inhibition in obese dogs.  


Apolipoprotein B100 (apoB100) is an essential component of very low density lipoprotein (VLDL) and low-density lipoprotein (LDL), both independent markers of cardiovascular risk. Nicotinic acid (NA) is an efficacious drug for decreasing VLDL and LDL, but the underlying mechanisms are unclear. For this purpose, six obese insulin-resistant dogs were given 350 mg/day of NA for 1 week and then 500 mg/day for 3 weeks. Turnover of apoB100-containing lipoproteins was investigated using stable isotope-labeled tracers. Multicompartmental modeling was used to derive kinetic parameters before and at the end of NA treatment. Hepatic diacylglycerol acyltransferase 2 (DGAT2), microsomal triglyceride transfer protein (MTP), hepatic lipase (HL), and adipose lipoprotein lipase (LPL) mRNA expression was also determined. NA treatment decreased plasma triglyceride (TG) (p < 0.001), VLDL-TG (p < 0.05), total cholesterol (p < 0.0001), and LDL cholesterol (p < 0.05), whereas plasma nonesterified fatty acids were unchanged. The decrease in VLDL-apoB100 concentration (p < 0.001) was the result of a lower absolute production rate (APR) (p < 0.001), despite a moderate decrease (p < 0.05) in fractional catabolic rate (FCR). LDL-apoB100 concentration was reduced (p < 0.05), an effect related to a decrease in LDL APR (p < 0.05) and no change in FCR. NA treatment reduced DGAT2 expression (p < 0.05), whereas MTP, HL, and LPL expression was unchanged. Our results suggest that NA treatment reduced VLDL and LDL concentration as a consequence of a decrease in VLDL production. PMID:20442223

Le Bloc'h, Jérôme; Leray, Véronique; Chetiveaux, Maud; Freuchet, Benjamin; Magot, Thierry; Krempf, Michel; Nguyen, Patrick; Ouguerram, Khadija



N-Succinyl-chitosan nanoparticles coupled with low-density lipoprotein for targeted osthole-loaded delivery to low-density lipoprotein receptor-rich tumors  

PubMed Central

N-Succinyl-chitosan (NSC) was synthesized and NSC nanoparticles (NPs) with loaded osthole (Ost) (Ost/NSC-NPs) were prepared by emulsion solvent diffusion. Subsequently, low-density lipoprotein (LDL)-mediated NSC-NPs with loaded Ost (Ost/LDL-NSC-NPs) were obtained by coupling LDL with Ost/NSC-NPs through amide linkage. The average particle size of Ost/NSC-NPs was approximately 145 nm, the entrapment efficiency was 78.28%±2.06%, and the drug-loading amount was 18.09%±0.17%. The release of Ost from Ost/NSC-NPs in vitro showed a more evident sustained effect than the native material. The half maximal inhibitory concentration of Ost/LDL-NSC-NPs was only 16.23% that of the free Ost at 24 hours in HepG2 cells. Ost inhibited HepG2 cell proliferation by arresting cells in the synthesis phase of the cell cycle and by triggering apoptosis. Cellular uptake and subcellular localization in vitro and near-infrared fluorescence real-time imaging in vivo showed that Ost/LDL-NSC-NPs had high targeting efficacy. Therefore, LDL-NSC-NPs are a promising system for targeted Ost delivery to liver tumor. PMID:24966673

Zhang, Chun-ge; Zhu, Qiao-ling; Zhou, Yi; Liu, Yang; Chen, Wei-liang; Yuan, Zhi-Qiang; Yang, Shu-di; Zhou, Xiao-feng; Zhu, Ai-jun; Zhang, Xue-nong; Jin, Yong



Antioxidant action of Vaccinium myrtillus extract on human low density lipoproteins in vitro: initial observations.  


Oxidative modifications of low density lipoproteins (LDL) are now recognised as one of the major processes in atherogenesis. Various drugs, as well as a number of natural products, have been proposed to inhibit such processes. Among the naturally-occurring constituents of plants which appear to possess antioxidant activity are polyphenolic compounds such as flavonoids. The aqueous extract of Vaccinium myrtillus is rich in such molecules. In this report, we describe the in vitro antioxidative potential of this extract on human LDL. The copper-induced oxidative modification of these lipoproteins was assessed using 1) measurement of oxidative resistance as determined by the lag-phase preceding conjugated diene formation; 2) quantification of the amount of lipoperoxides and thiobarbituric acid-reactive substances generated, and measurement of the modification in the net negative electrical charge of the lipoproteins, over a 7-hour time course experiment. Trace amounts of V myrtillus extract (15 to 20 micrograms/mL) induce statistically significant changes in the oxidation behaviour of LDL, which include 1) prolongation of the lag-phase of conjugated diene production (P < 0.01); 2) reduction in the formation of lipoperoxides and of thiobarbituric acid-reactive substances up to 7 hours and especially between 1 and 5 hours (P < 0.01); and 3) inhibition of modification in the net negative charge of LDL. These results demonstrate that V myrtillus extract exerts potent protective action on LDL particles during in vitro copper-mediated oxidation. Calculation of IC50 values indicates that, on a molar basis, this extract may indeed be more potent than either ascorbic acid or butylated hydroxytoluene in the protection of LDL particles from oxidative stress. PMID:9182074

Laplaud, P M; Lelubre, A; Chapman, M J



Uptake of low density lipoproteins by rat tissues. Special emphasis on the luteinized ovary.  

PubMed Central

The aim of this study was to determine how luteal cells of the hormone-primed (luteinized) ovary process low density lipoproteins (LDL). Ovary uptake of perfused 125I-LDL was assessed by tissue levels of radioactivity; the distribution of LDL protein in cells was assessed on autoradiograms of the fixed tissue; and the level of stimulation of steroidogenesis, as well as degradation of LDL protein, was assessed on effluent perfusion samples. Human LDL ligand used in these studies was rigorously defined biochemically and physiologically. Homologous (rat) LDL was used as a special ligand control. Other tissue controls included the use of perfused or in vivo-infused luteinized ovaries from animals pretreated to reduce circulating lipoprotein levels, perfused ovaries from a second hormone-primed model, perfused liver from estrogen-treated rats, and isolated and cultured cells from the same ovarian tissues used in the perfusion experiments. The results show that perfused LDL promptly stimulates steroidogenesis. However, the labeled protein moiety of the LDL is not interiorized by the luteal cells, nor is there evidence of LDL protein degradation in the effluent samples. In contrast, internalization of the ligand occurs when luteal cells are incubated with the ligand in vitro. We have observed also that uptake of the 125I-LDL by the ovary can be displaced equally well by excess unlabeled LDL or HDL3. Overall, these experiments suggest that in the intact luteinized ovary, LDL binds to the same sites on the cell surface where HDL "binds," and that LDL cholesterol must be obtained by these steroid hormone-producing cells by a mechanism that does not require internalization of the intact lipoprotein particle. Images PMID:3711341

Reaven, E; Chen, Y D; Spicher, M; Hwang, S F; Mondon, C E; Azhar, S



Low density lipoprotein apheresis in treatment of hyperlipidemia: experience with four different technologies.  


The prognosis of patients suffering from severe hyperlipidaemia (HLP), sometimes combined with elevated lipoprotein (a) levels, and coronary heart disease (CHD) refractory to diet and lipid lowering drugs is poor. A new therapeutic option for such patients is regular treatment with low density lipoprotein (LDL) apheresis. In total 33 patients (16 males, 17 female, aged 43.8+/-14.3 years), suffering from severe HLP resistant to diet and lipid lowering drugs, were treated for 62.3+/-21.3 (range, 1-113) months with LDL-apheresis. Four different LDL-apheresis systems were used: the dextran sulfate adsorption for 28 of 33 (Liposorber, Kaneka, Japan), immunoadsorption for 2 of 33 (Therasorb, Baxter, Germany), LDL-hemoperfusion for 2 of 33 (Dali, Fresenius, Germany), and the immunoadsorption system with special antilipoprotein (a) columns for 1 of 33 patients (Lipopak, Pocard, Russia). Before applying LDL-apheresis, 27 of 33 patients suffered from CHD with severe angina pectoris symptoms, a history of myocardial infarction or coronary artery venous bypass (CAVB). With LDL-apheresis, reductions (p < 0.05) of 46% for total cholesterol, 49% for LDL, 28% for Lp(a), and 38% for triglycerides were reached. Severe side-effects, such as shock or allergic reactions, were very rare (0.5%). In the course of treatment an improvement in general well-being and increased performance were experienced in 29 of 33 patients. In 23 of 27 patients suffering from CHD, a reduction of 60 to 100% of nitrate medication was observed. Regarding the different apheresis systems used, there were no significant differences with respect to the clinical outcome and concerning total cholesterol, LDL, HDL, and triglyceride concentrations. But, in respect to elevated lipoprotein (a) levels, the immunoadsorption method using special anti-lipoprotein (a) columns seems to be the most effective (-57% versus -25% [Kaneka, p < 0.05] or -23% [Baxter, p < 0.05]). The present data clearly demonstrate that treatment with LDL-apheresis in patients suffering from severe HLP, refractory to maximum conservative therapy, is effective and safe in long-term application. PMID:10910023

Bambauer, R; Schiel, R; Latza, R



[Cholesterol bound to high density lipoproteins: critical review of the methods of analysis and personal data].  


It is widely known that atherosclerosis through its complication, i.e. heart and brain infarction, is at the present the main cause of death. The atherosclerotic process has been shown in correlation with hyperlipemia especially as far as the plasma lipoprotein cholesterol level is concerned. A preminent role in removing cholesterol from tissues and arterial walls then in preventing atherosclerosis is played by a specific class of plasma lipoproteins, the high density lipoproteins (HDL). Since the HDL-colesterol level seems to have an inverse correlation with the atherosclerotic disease it is of primary importance to define a reliable and reproducible technique to measure it. One of the aims of this paper was to examine the different methods now available for such a determination. This analysis has underlined the discrepancy among the reference values reported in the literature. However, all the authors agree that only the simultaneous measurement of total and HDL-colesterol levels is of prognostic value. Personal studies are here reported on the relationship between total and HDL-colesterol levels and risk factor of cardiovascular diseases. The two mentioned laboratory analyses have been performed on blood samples from 250 between male and female human subjects of different age. The obtained results show that the highest HDL-colesterol concentrations determined by a lipoprotein precipitation procedure with dextran sulphate, are typical in the first ten years of life both in male and in female, while the lowest levels of plasma HDL-cholesterol have been evintiated during the fifth decade of life, when the total cholesterol and the risk of cardiovascular complications rich the highest values. In a following set of investigations, the already examined blood parameters together with the risk factor values have been examined in two groups of subjects, the first one represented by adult healthy persons the second one by patients of similar age from a cardiovascular division. The mean levels of total colesterol have been shown similar in both the experimental groups, while plasma HDL-cholesterol is significantly higher in the healthy group. This discrepancy is the cause of definitively higher risk factors in the hospitalized patients. In conclusion, the reported data furtherly stress that the total cholesterol values do not give "per se" any indication of atherogenic risk. They are useful only when examined together with the HDL-cholesterol levels. From that the opportunity to always include the determination of plasma HDL-cholesterol screening lipemic profiles. PMID:7137764

Orso Giacone, G



Similarity in the distribution of F(2)-isoprostanes in the lipid subfractions of atherosclerotic plaque and in vitro oxidised low density lipoprotein.  


Oxidation of low density lipoprotein (LDL) in vivo is thought to play a critical role in the initiation of atherosclerosis. F(2)-isoprostanes are compounds resulting from non-enzymatic oxidation of arachidonic acid and elevated levels are present in human atherosclerotic plaque. However, little is known about the formation of F(2)-isoprostanes in plaque lesions or their distribution in lipid subclasses. Given that LDL and tissue lipid subfractions (such as phospholipids, cholesterol esters and triglycerides) all contain significant levels of arachidonic acid, the aim of this study was to examine the relative distribution of F(2)-isoprostanes in the different lipid fractions of LDL oxidised in vitro, and compare this to the distribution in atherosclerotic plaque. The results reveal that while the majority of F(2)-isoprostanes are present in the phospholipid or surface lipid fractions, the core lipids (cholesterol esters/triglycerides) contribute at least 10% of the total F(2)-isoprostanes in both LDL oxidised in vitro and human atherosclerotic plaque. The remarkably similar profiles between the oxidised LDL and advanced atherosclerotic plaque suggests oxidation in vivo, is predominantly via non-enzymatic processes directed towards the surface lipids. PMID:12189049

Waddington, E I; Puddey, I B; Mori, T A; Croft, K D



Gold Nanocrystal Labeling Allows Low Density Lipoprotein Imaging From The Subcellular To Macroscopic Level  

PubMed Central

Low density lipoprotein (LDL) plays a critical role in cholesterol transport and is closely linked to the progression of several diseases. This motivates the development of methods to study LDL behavior from the microscopic to whole-body level. We have developed an approach to efficiently load LDL with a range of diagnostically active nanocrystals or hydrophobic agents. We performed focused experiments on LDL labeled with gold nanocrystals (Au-LDL). The labeling procedure had minimal effect on LDL size, morphology or composition. Biological function was found to be maintained from both in vitro and in vivo experiments. Tumor bearing mice were injected intravenously with LDL, DiR-LDL, Au-LDL or a gold-loaded nanoemulsion. LDL accumulation in the tumors was detected with whole body imaging methods, such as computed tomography (CT), spectral CT and fluorescence imaging. Cellular localization was studied with transmission electron microscopy (TEM) and fluorescence techniques. In conclusion, this LDL labeling procedure should permit the study of lipoprotein biointeractions in unprecedented detail. PMID:24127782

Allijn, Iris E.; Leong, Wei; Tang, Jun; Gianella, Anita; Mieszawska, Aneta J.; Fay, Francois; Ma, Ge; Russell, Stewart; Callo, Catherine B.; Gordon, Ronald E.; Korkmaz, Emine; Post, Jan Andries; Zhao, Yiming; Gerritsen, Hans C.; Thran, Axel; Proksa, Roland; Daerr, Heiner; Storm, Gert; Fuster, Valentin; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J.M.



Cholesteryl ester accumulation in macrophages incubated with low density lipoprotein pretreated with cigarette smoke extract  

SciTech Connect

Although cigarette smoking is one of the major risk factors for atherosclerosis and coronary heart disease, the precise mechanisms of its adverse effects have not been fully elucidated. We incubated low density lipoprotein (LDL) with cigarette smoke (CS) extract and examined the incorporation of the lipoprotein by macrophages in vitro. When incubated with macrophages, LDL pretreated with CS extract (100 micrograms/ml) stimulated cholesteryl (/sup 14/C)oleate synthesis approximately equal to 12.5-fold that with unmodified LDL and transformed macrophages to cells rich in lipid droplets positively stained with oil red O. Enhancement in cholesteryl ester synthesis was dependent on the concentration of CS-modified LDL and exhibited saturation kinetics. When subjected to electrophoreses, CS-modified LDL migrated to a more anionic position than did unmodified LDL and showed extensive fragmentation of apolipoprotein B. This LDL modification depended upon the incubation time and concentration of the CS extract. Superoxide dismutase inhibited modification of LDL by 52%, suggesting that superoxide anion is, at least in part, involved. These results suggest that CS extract alters LDL into a form recognized and incorporated by macrophages. Such modification if it occurs in vivo, could explain the increased incidence of atherosclerosis and coronary heart disease in smokers.

Yokode, M.; Kita, T.; Arai, H.; Kawai, C.; Narumiya, S.; Fujiwara, M.



Role of dietary supplements in lowering low-density lipoprotein cholesterol: a review.  


Coronary heart disease (CHD) remains a major source of morbidity and mortality. As the epidemic of obesity, diabetes, and hypertension continues to grow among young adults, the population at risk for atherosclerotic CHD is ever increasing. More than a century of laboratory and human findings link cholesterol levels with a propensity to develop atherosclerosis. Low-density lipoprotein (LDL) is the major atherogenic lipoprotein, and numerous clinical trials have shown the efficacy of lowering LDL-cholesterol (LDL-C) for reducing CHD risk. New trial data have resulted in LDL-C goals being lowered over time and expansion of the population of patients that are candidates for LDL-lowering therapy to decrease their lifetime risk of CHD. Although statins are relatively safe and well tolerated, there are still significant numbers of patients who cannot tolerate them and many others who only require mild LDL-C reduction and prefer nonprescription alternatives to statin therapy. A number of dietary supplements and functional foods have been suggested to reduce LDL-C levels, but only a few have withstood the rigors of randomized controlled trials. Here we review the evidence in support of dietary supplements and their LDL-C-lowering effects. We also review supplements that, after initial excitement about their purported effect, were not found to lower LDL-C significantly. PMID:21122657

Nijjar, Prabhjot S; Burke, Frances M; Bloesch, Annette; Rader, Daniel J



High-density lipoprotein-based contrast agents for multimodal imaging of atherosclerosis.  


Lipoproteins, natural nanoparticles, have a well-recognized biological role and are highly suitable as a platform for delivering imaging agents. The ease with which both the exterior and interior of the particles can be modified permits the creation of multifunctional nanoparticles for imaging as well as the delivery of therapeutics. Importantly, their endogenous nature may make them biocompatible and biodegradable and allows them to avoid the recognition of the reticuloendothelial system. In particular, high-density lipoproteins (HDL) are of interest, because of their small size they can easily cross the endothelium and penetrate the underlying tissue. We summarize here the progress in establishing HDL as a vector for delivering a variety of diagnostically active materials to vulnerable atherosclerotic plaques in mouse models of atherosclerosis. By loading various types of image-enhancing compounds into either the core or surface of HDL, they can be visualized by different imaging modalities (MRI, CT, optical). By rerouting of HDL away from plaque macrophages, imaging of biological processes in diseases besides atherosclerosis may also be achieved. PMID:19815819

Skajaa, Torjus; Cormode, David P; Falk, Erling; Mulder, Willem J M; Fisher, Edward A; Fayad, Zahi A



Abnormal high-density lipoprotein induces endothelial dysfunction via activation of Toll-like receptor-2.  


Endothelial injury and dysfunction (ED) represent a link between cardiovascular risk factors promoting hypertension and atherosclerosis, the leading cause of death in Western populations. High-density lipoprotein (HDL) is considered antiatherogenic and known to prevent ED. Using HDL from children and adults with chronic kidney dysfunction (HDL(CKD)), a population with high cardiovascular risk, we have demonstrated that HDL(CKD) in contrast to HDL(Healthy) promoted endothelial superoxide production, substantially reduced nitric oxide (NO) bioavailability, and subsequently increased arterial blood pressure (ABP). We have identified symmetric dimethylarginine (SDMA) in HDL(CKD) that causes transformation from physiological HDL into an abnormal lipoprotein inducing ED. Furthermore, we report that HDL(CKD) reduced endothelial NO availability via toll-like receptor-2 (TLR-2), leading to impaired endothelial repair, increased proinflammatory activation, and ABP. These data demonstrate how SDMA can modify the HDL particle to mimic a damage-associated molecular pattern that activates TLR-2 via a TLR-1- or TLR-6-coreceptor-independent pathway, linking abnormal HDL to innate immunity, ED, and hypertension. PMID:23477738

Speer, Thimoteus; Rohrer, Lucia; Blyszczuk, Przemyslaw; Shroff, Rukshana; Kuschnerus, Kira; Kränkel, Nicolle; Kania, Gabriela; Zewinger, Stephen; Akhmedov, Alexander; Shi, Yi; Martin, Tina; Perisa, Damir; Winnik, Stephan; Müller, Maja F; Sester, Urban; Wernicke, Gabriel; Jung, Andreas; Gutteck, Ursula; Eriksson, Urs; Geisel, Jürgen; Deanfield, John; von Eckardstein, Arnold; Lüscher, Thomas F; Fliser, Danilo; Bahlmann, Ferdinand H; Landmesser, Ulf



Maternal loading with very low-density lipoproteins stimulates fetal surfactant synthesis  

PubMed Central

We examined whether administration of very low-density lipoproteins (VLDL) to pregnant rats increases surfactant phosphatidylcholine (PtdCho) content in fetal pre-type II alveolar epithelial cells. VLDL-triglycerides are hydrolyzed to fatty acids by lipoprotein lipase (LPL), an enzyme activated by heparin. Fatty acids released by LPL can incorporate into the PtdCho molecule or activate the key biosynthetic enzyme cytidylyltransferase (CCT). Dams were given BSA, heparin, VLDL, or VLDL with heparin intravenously. Radiolabeled VLDL given to the pregnant rat crossed the placenta and was distributed systemically in the fetus and incorporated into disaturated PtdCho (DSPtdCho) in pre-type II cells. Maternal administration of VLDL with heparin increased DSPtdCho content in cells by 45% compared with control (P < 0.05). VLDL produced a dose-dependent, saturable, and selective increase in CCT activity. VLDL did not significantly alter immunoreactive CCT content but increased palmitic, stearic, and oleic acids in pre-type II cells. Furthermore, hypertriglyceridemic apolipoprotein E knockout mice contained significantly greater levels of DSPtdCho content in alveolar lavage and CCT activity compared with either LDL receptor knockout mice or wild-type controls that have normal serum triglycerides. Thus the nutritional or genetic modulation of serum VLDL-triglycerides provides specific fatty acids that stimulate PtdCho synthesis and CCT activity thereby increasing surfactant content. PMID:12114192

Ryan, Alan J.; Medh, Jheem D.; McCoy, Diann M.; Salome, Ronald G.; Mallampalli, Rama K.



Translation of two aggregated low-density lipoproteins within blood plasma: a mathematical model.  


Arteriosclerosis is a disease in which the artery walls get thicker and harder. Atherosclerosis is a specific form of arteriosclerosis which allows less blood to travel through the artery and increases blood pressure. Low-density lipoproteins (LDLs) and their ability to aggregate are important in atherosclerosis. In the present study we develop a mathematical model that describes the translation of two aggregated LDSs through blood plasma. We model the two aggregated LDLs as an inverted oblate spheroid and the flow as a creeping steady incompressible axisymmetric one. The mathematical tools that we used are the Kelvin inversion and the semi-separation of variables in the spheroidal coordinate systems. The stream function is given as a series expansion of even order terms of combinations of Gegenbauer functions of angular and radial dependence. The analytical solution is expected to give insight into the study of the various chemical precipitation methods used for the precipitation of lipoproteins, as this is the first step for the measurement of their concentration within blood plasma. PMID:25417024

Hadjinicolaou, Maria; Protopapas, Eleftherios



Characterization of Lipid Composition and High-Density Lipoprotein Function in HIV-Infected Individuals on Stable Antiretroviral Regimens.  


There is an increase in the cardiovascular disease (CVD) morbidity in individuals infected with HIV that may be due to inflammatory lipid modulation not captured by traditional lipid measures. The objective of this study was to perform advanced lipoprotein phenotyping inclusive of the high-density lipoprotein (HDL) cholesterol efflux capacity and lipoprotein particle concentration and size in a well-phenotyped group of 118 patients infected with HIV. We used simple and multivariable analyses to determine the associations between advanced lipoprotein parameters and known cardiometabolic risk factors. Participants were on stable antiretroviral therapy (ART) and had benign traditional lipid panels [median total cholesterol, low-density lipoprotein (LDL)-C, HDL-C, and triglycerides of 178?mg/dl, 108?mg/dl, 44?mg/dl, and 122.5?mg/dl, respectively]. However, advanced lipoprotein phenotyping demonstrated an elevation of LDL particle number (median of 1,233?nmol/liter) and a decrease in LDL size (median of 20.4?nm), along with a decrease in protective, large HDL particles (median of 3.15??mol/liter) and reduced HDL cholesterol efflux capacity in comparison to controls of other studies. HDL cholesterol efflux capacity was associated with HDL levels (?=0.395, p<0.001), small LDL particle concentration (?=-0.198, p=0.031), insulin sensitivity by the Matsuda index (?=0.218, p=0.029), and the Framingham Risk Score (?=-0.184, p=0.046). We demonstrate an atherogenic lipoprotein profile by NMR spectroscopy and HDL efflux measurement in a group of HIV-infected patients on stable ART with normal lipid panels. PMID:25416403

Munger, Alana M; Chow, Dominic C; Playford, Martin P; Parikh, Nisha I; Gangcuangco, Louie Mar A; Nakamoto, Beau K; Kallianpur, Kalpana J; Ndhlovu, Lishomwa C; Shikuma, Cecilia M; Mehta, Nehal N



Efficacy and safety of a new whole-blood low-density lipoprotein apheresis system (Liposorber D) in severe hypercholesterolemia.  


Low-density lipoprotein (LDL) apheresis is an extracorporeal modality to lower LDL cholesterol. While most of the devices eliminate LDL particles from plasma, a recently introduced whole-blood perfusion column (DALI) adsorbs lipoproteins directly from whole blood. We investigated the efficacy and safety of a new whole-blood LDL apheresis system (Liposorber D) in 10 patients with severe hypercholesterolemia in a multicenter trial. In 93 LDL aphereses, the mean reduction in LDL cholesterol and lipoprotein(a) was 62.2 +/- 11.5% and 55.6 +/- 16.9%, respectively (P < 0.01). If hemodilution during apheresis was considered, the reductions were 58.0 +/- 10.9 and 55.3 +/- 10.9%, respectively (P < 0.01), while high-density lipoprotein (HDL) cholesterol did not change significantly. Three mild episodes of hypocalcemia and two mild episodes of arterial hypotension were observed; however, LDL apheresis could be continued in each case. In conclusion, the new whole-blood LDL apheresis with Liposorber D is a safe, simple, and useful modality to reduce LDL cholesterol and lipoprotein(a) in cardiovascular high-risk patients. PMID:14678426

Otto, Carsten; Kern, Peter; Bambauer, Rolf; Kallert, Stefan; Schwandt, Peter; Parhofer, Klaus G



High-density Lipoprotein Increases the Uptake of Oxidized Low Density Lipoprotein via PPAR?/CD36 Pathway in Inflammatory Adipocytes  

PubMed Central

Aim: Previous studies have demonstrated that the dysregulated-secretion of adipokines by adipocytes may contribute to obesity-associated atherosclerosis (As) and high density lipoprotein (HDL) may protect against atherogenesis through multiple pathways. This study was to explore the effect of HDL on the oxLDL uptake in inflammatory adipocytes stimulated by endotoxin lipopolysaccharide (LPS) and the possible mechanism. Methods and Results: 3T3-L1 adipocytes were cultured and induced to differentiation and maturation. Acute inflammation in adipocytes was induced by LPS (100 ng/ml) for 6 hours. The adipocytes were pretreated with HDL in various concentrations (10, 50, 100 ?g/ml) for 16 hours or with specific PPAR? antagonist (GW9662, 10 ?M) or agonist (Rosiglitazone, 10 ?M) for 30 min before administration of LPS. The results showed that LPS significantly increased the release of inflammation-related adipokines, such as monocyte chemoattractant protein-1 (MCP-1), plasminogen activator inhibitor 1 (PAI-1), tumor necrosis factor-alpha (TNF-?), interleukin (IL)-8 and IL-6, while decreasing the release of leptin and adiponectin. Meanwhile, LPS reduced the uptake and degradation of 125I-oxLDL, and down-regulated the expression of PPAR? and CD36. Pretreatment with HDL dose-dependently affected the release of IL-8 and IL-6 and the reduced uptake and degradation of oxLDL of adipocytes stimulated by LPS, accompanied with marked upregulation of PPAR? and CD36 expression. Pretreatment with GW9662 markedly inhibited the upregulation of CD36 expression mediated by HDL (100 ?g/ml), while the effects of Rosiglitazone were opposite to GW9662. Conclusions: HDL may increase oxLDL uptake of inflammatory adipocytes stimulated by LPS via upregulation of PPAR?/CD36 pathway, which may be a new mechanism of anti-atherosclerosis mediated by HDL.

Zhong, Qiaoqing; Zhao, Shuiping; Yu, Bilian; Wang, Xing; Matyal, Robina; Li, Yunping; Jiang, Zhisheng



ABCG2 polymorphism is associated with the low-density lipoprotein cholesterol response to rosuvastatin.  


The ATP-binding cassette G2 (ABCG2) c.421C>A (rs2231142) polymorphism influences the pharmacokinetics of rosuvastatin. We examined whether this polymorphism influences the low-density lipoprotein cholesterol (LDL-C)-lowering efficacy of the drug. In 305 Chinese patients with hypercholesterolemia who were treated with rosuvastatin at a dosage of 10 mg daily, the c.421A variant was found to be significantly associated with greater reduction in LDL-C level, in a gene-dose-dependent manner. As compared with subjects with the c.421CC genotype, those with the c.421AA genotype showed a 6.9% greater reduction in LDL-C level, which would be equivalent to the effect obtained by doubling the dose of rosuvastatin. PMID:20130569

Tomlinson, B; Hu, M; Lee, V W Y; Lui, S S H; Chu, T T W; Poon, E W M; Ko, G T C; Baum, L; Tam, L S; Li, E K



Clinical experience and future directions for low-density lipoprotein apheresis in the United States.  


The United States Liposorber Study was a 22 week randomized controlled study of low-density lipoprotein (LDL) apheresis with an optional follow-up phase. The procedure was found to acutely lower LDL cholesterol by up to 81%, have good tolerability, and produce a reduction in the frequency of cardiovascular events. Studies outside the United States have found therapy with LDL apheresis to be associated with a favorable clinical outcome including improved myocardial perfusion, but variable regression of coronary artery disease (CAD). Improvement in blood viscosity and endothelial function may help explain the symptomatic benefits observed with relatively small changes in angiography. Based upon favorable clinical experience, LDL apheresis using dextran sulfate cellulose columns has recently received approval for commercialization in the United States in patients with inadequate responses to diet and drug therapy and LDL levels > or = 200 mg with CAD present or LDL levels > or = 300 mg/dl without CAD. PMID:10225747

Gordon, B R; Saal, S D



Statin-mediated low-density lipoprotein lowering in chronic congestive heart failure.  


Many theories and clinical trials have attempted to address the effect of low-density lipoprotein (LDL) lowering in chronic congestive heart failure (CHF). The current evidence suggests that there is no convincing reason for administering statins to patients with nonischemic heart failure. Although they do not reduce the mortality rate, statins reduce LDL cholesterol and may provide some benefit to patients with ischemic heart failure. In contrast, some authors believe that statin therapy may actually worsen outcomes in patients with CHF, especially if there is excessive reduction in LDL cholesterol. This review discusses the theories attempting to link the adverse effects of statin-mediated LDL lowering in CHF to increased levels of endotoxin or reduced levels of coenzyme Q10. In addition, the 2 largest randomized, double-blind, placebo-controlled clinical trials (CORONA and GISSI-HF) were discussed. It is clear that more trials are needed to definitely ascertain the effect of statins on CHF. PMID:23154655

Kosmas, Constantine E; Alkhawam, Hassan; El-Hunjul, Mohammed; Wagman, Gabriel; Kahn, Mark R; Grady, Kathleen M; Vittorio, Timothy J



High density lipoprotein cholesterol: an evolving target of therapy in the management of cardiovascular disease  

PubMed Central

Since the pioneering work of John Gofman in the 1950s, our understanding of high density lipoprotein cholesterol (HDL-C) and its relationship to coronary heart disease (CHD) has grown substantially. Numerous clinical trials since the Framingham Study in 1977 have demonstrated an inverse relationship between HDL-C and one’s risk of developing CHD. Over the past two decades, preclinical research has gained further insight into the nature of HDL-C metabolism, specifically regarding the ability of HDL-C to promote reverse cholesterol transport (RCT). Recent attempts to harness HDL’s ability to enhance RCT have revealed the complexity of HDL-C metabolism. This review provides a detailed update on HDL-C as an evolving therapeutic target in the management of cardiovascular disease. PMID:18629371

Kapur, Navin K; Ashen, Dominique; Blumenthal, Roger S



Evaluation of various electrode materials for detection of oxidized low-density lipoproteins.  


Measurement of oxidized low-density lipoprotein (LDL) generated by oxidative stress of various kinds might be useful for evaluating the risk of cardiovascular disease. We evaluated some electrode materials to detect oxidized LDL electrochemically. Some carbon nanotube dispersions were studied as electrode materials. Native LDL was isolated from normal human serum using ultracentrifugation. Oxidized LDL was prepared by treating the native LDL with CuSO4. Electrodes were fabricated by depositing the nanotube dispersion on a gold electrode, with subsequent drying. The potential change of the electrode against a reference electrode was monitored before and after adding native LDL or oxidized LDL. Only acid-treated carbon nanotubes were able to discriminate both LDL preparations, perhaps because of the carboxylic acid groups introduced on the nanotube by acid treatment. PMID:23627060

Takeda, Seiji; Hui, Shu-Ping; Fuda, Hirotoshi; Jin, Shigeki; Sakurai, Toshihiro; Ishii, Atsushi; Mukasa, Koichi; Sueoka, Kazuhisa; Chiba, Hitoshi



Interrelatedness between C-reactive protein and oxidized low-density lipoprotein.  


Abstract C-reactive protein (CRP) is a marker of inflammation. Atherosclerosis is now recognized as inflammatory disease, and it seems that CRP directly contributes to atherogenesis. Oxidation of low-density lipoprotein (LDL) molecule increases the uptake of lipid products by macrophages leading to cholesterol accumulation and subsequent foam cell formation. The elevated levels of high sensitivity CRP (hsCRP) and oxidized LDL (OxLDL) in the blood were found to be associated with cardiovascular diseases (CVD). In this review, we highlighted the evidence that CRP and OxLDL are involved in interrelated (patho) physiological pathways. The findings on association between hsCRP and OxLDL in the clinical setting will be also summarized. PMID:25010779

Obradovic, Milan M; Trpkovic, Andreja; Bajic, Vladan; Soskic, Sanja; Jovanovic, Aleksandra; Stanimirovic, Julijana; Panic, Milos; Isenovic, Esma R



Anticipatory Role of High Density Lipoprotein and Endothelial Dysfunction: An Overview  

PubMed Central

High Density Lipoprotein (HDL) has been witnessed to possess a range of different functions that contribute to its atheroprotective effects. These functions are: the promotion of macrophage cholesterol efflux, reverse cholesterol transport, anti-inflammatory, anti-thrombotic, anti-apoptotic, pro-fibrinolytic and anti-oxidative functions. Paraoxonase 1 (PON1) is an HDL associated enzyme esterase/homocysteinethiolactonase that contributes to the anti-oxidant and anti-atherosclerotic capabilities of HDL. PON1 is directly involved in the etiopathogenesis of atherosclerosis through the modulation of nitric oxide (NO) bioavailability. The aim of this review is to summarize the role of HDL on endothelial homeostasis, and also to describe the recently characterized molecular pathways involved. PMID:25598849

Eren, Esin; Y?lmaz, Necat; Aydin, Ozgur; Ellida?, Hamit Y



Inhibition of human low density lipoprotein oxidation by flavonols and their glycosides.  


Antioxidative effects of the flavonols and their glycosides, i.e., quercetin (Q), quercetin galactopyranoside (QG), quercetin rhamnolpyranoside (QR), rutin (R), morin (MO), myrecetin (MY), kaempferol (K) and kaempferol glucoside (KG), against free radical initiated peroxidation of human low density lipoprotein (LDL) were studied. The peroxidation was initiated either by a water-soluble initiator 2,2'-azobis(2-amidino propane hydrochloride) (AAPH), or by cupric ion (Cu2+). The reaction kinetics were monitored either by the uptake of oxygen and the depletion of alpha-tocopherol (TOH) presented in the native LDL, or by the formation of thiobarbituric acid reactive substances (TBARS). Kinetic analysis of the antioxidation process demonstrates that these flavonols and their glycosides are effective antioxidants against AAPH- and Cu(2+)-initiated LDL peroxidation, the flavonols bearing ortho-dihydroxyl groups possess significantly higher antioxidant activity than those bearing no such functionalities, and the glycosides are less active than their parent aglycones. PMID:15081861

Hou, Lifen; Zhou, Bo; Yang, Li; Liu, Zhong-Li



Low density lipoprotein bionanoparticles: From cholesterol transport to delivery of anti-cancer drugs  

PubMed Central

In this review article, we highlight the importance of low-density lipoprotein (LDL) and its implications in the field of drug delivery to cancer cells. LDL is naturally occurring bionanoparticles (BNP) with a size of 18–25 nm. These BNPs specifically transport cholesterol to cells expressing the LDL receptors (LDLRs). Several tumors overexpress LDLRs, presumably to provide cholesterol for sustaining a high rate of membrane synthesis. LDL BNPs are biocompatible and biodegradable, favorably bind hydrophobic and amphiphilic drugs, are taken up by a receptor-mediated mechanism, have a half-life of 2–4 days, and can be rerouted. Drugs can be loaded onto LDL BNPs by surface loading, core loading, and apoprotein interaction. LDL may be used as a drug carrier for treatment of atherosclerosis, cancer, and in photodynamic therapies.

Harisa, Gamaleldin I.; Alanazi, Fars K.



Flavonoids from Lindera glauca Blume as low-density lipoprotein oxidation inhibitors.  


In order to identify antioxidant flavonoids from Lindera glauca Blume, we performed phytochemical analysis of L. glauca Blume heartwood and isolated eight flavonoids - lindeglaucol (1), lindeglaucone (2), cilicicone B (3), tamarixetin 3-O-?-L-rhamnoside (4), procyanidin A2 (5), cinnamtannin B1 (6), cinnamtannin D1 (7), and procyanidin A1 (8) - through repeated column chromatography over silica gel (SiO?), octadecyl silica gel (ODS) and Sephadex LH-20. The chemical structures of compounds 1-8 were elucidated from spectroscopic data (NMR, IR and MS). The low-density lipoprotein oxidation inhibitory activities of the isolated compounds were evaluated in vitro by using the thiobarbituric acid reactive substances assay. Compounds 5-8 exhibited high inhibition activity, comparable to the positive control butyl hydroxyl toluene. Compounds 2 and 3 were slightly less active, while 1 and 4 expressed low activity. PMID:24499267

Huh, Gyu-Won; Park, Ji-Hae; Kang, Ji-Hyun; Jeong, Tae-Sook; Kang, Hee Cheol; Baek, Nam-In



Pharmacogenetics of paraoxonase activity: elucidating the role of high-density lipoprotein in disease  

PubMed Central

PON1 is a key component of high-density lipoproteins (HDLs) and is at least partially responsible for HDL's antioxidant/atheroprotective properties. PON1 is also associated with numerous human diseases, including cardiovascular disease, Parkinson's disease and cancer. In addition, PON1 metabolizes a broad variety of substrates, including toxic organophosphorous compounds, statin adducts, glucocorticoids, the likely atherogenic l-homocysteine thiolactone and the quorum-sensing factor of Pseudomonas aeruginosa. Numerous cardiovascular and antidiabetic pharmacologic agents, dietary macronutrients, lifestyle factors and antioxidant supplements affect PON1 expression and enzyme activity levels. Owing to the importance of PON1 to HDL function and its individual association with diverse human diseases, pharmacogenomic interactions between PON1 and the various factors that alter its expression and activity may represent an important therapeutic target for future investigation. PMID:24024900

Kim, Daniel Seung; Marsillach, Judit; Furlong, Clement E; Jarvik, Gail P



In vivo tumor imaging in mice with near-infrared: low density lipoprotein conjugates  

NASA Astrophysics Data System (ADS)

Near-infrared (NIR) fluorescence imaging possesses many advantages as an in vivo non-invasive optical imaging modality for studying diseases in preclinical models. In this study, low density lipoprotein(LDL) fraction was quickly isolated from human plasma by modified heparin-citrate precipitation method and then conjugated to near infrared fluorescence dye ICG-Der-02 with excitation and emission wavelengths at 760nm and 830nm, respectively. The conjugates LDL-ICG-Der-02 were intravenously injected into the mice bearing different tumor models. And real time series fluorescence tumor images at different intervals of post-injection were in vivo acquired by a self-built NIR reflectance fluorescence imaging system. Results demonstrated that LDL-ICG-Der-02 conjugates could efficiently target to the tumor sites that over-expressed LDL receptors and could be completely eliminated at last.

Chen, Xinyang; Deng, Dawei; Liu, Fei; Li, Hui; Qian, Zhiyu; Gu, Yueqing



A mathematical model for the blood plasma flow around two aggregated low-density lipoproteins.  


The rheological behaviour of low-density lipoprotein (LDL) particles within the blood plasma and their role in atherogenesis, as well as their ability to aggregate under certain circumstances, is the subject of many clinical tests and theoretical studies aiming at the prevention of atherosclerosis. In the present study we develop a mathematical model that describes the flow of the blood plasma around two aggregated LDLs. We consider the flow as a creeping steady incompressible axisymmetric one, while the two aggregated LDLs are described by an inverted oblate spheroid. The mathematical methods of Kelvin inversion and the semi-separation of variables are employed and analytical expressions for the stream function are derived. These expressions are expected to be useful for further model developing and screening as well as the theoretical justification and validation of laboratory results. PMID:25417023

Hadjinicolaou, Maria



Apolipoprotein B100 quality control and the regulation of hepatic very low density lipoprotein secretion  

PubMed Central

Abstract Apolipoprotein B (apoB) is the main protein component of very low density lipoprotein (VLDL) and is necessary for the assembly and secretion of these triglyceride (TG)-rich particles. Following release from the liver, VLDL is converted to low density lipoprotein (LDL) in the plasma and increased production of VLDL can therefore play a detrimental role in cardiovascular disease. Increasing evidence has helped to establish VLDL assembly as a target for the treatment of dyslipidemias. Multiple factors are involved in the folding of the apoB protein and the formation of a secretion-competent VLDL particle. Failed VLDL assembly can initiate quality control mechanisms in the hepatocyte that target apoB for degradation. ApoB is a substrate for endoplasmic reticulum associated degradation (ERAD) by the ubiquitin proteasome system and for autophagy. Efficient targeting and disposal of apoB is a regulated process that modulates VLDL secretion and partitioning of TG. Emerging evidence suggests that significant overlap exists between these degradative pathways. For example, the insulin-mediated targeting of apoB to autophagy and postprandial activation of the unfolded protein response (UPR) may employ the same cellular machinery and regulatory cues. Changes in the quality control mechanisms for apoB impact hepatic physiology and pathology states, including insulin resistance and fatty liver. Insulin signaling, lipid metabolism and the hepatic UPR may impact VLDL production, particularly during the postprandial state. In this review we summarize our current understanding of VLDL assembly, apoB degradation, quality control mechanisms and the role of these processes in liver physiology and in pathologic states. PMID:25013401

Fisher, Eric; Lake, Elizabeth; McLeod, Roger S



Effect of bicarbonate on iron-mediated oxidation of low-density lipoprotein  

NASA Astrophysics Data System (ADS)

Oxidation of low-density lipoprotein (LDL) may play an important role in atherosclerosis. We studied the effects of bicarbonate/CO2 and phosphate buffer systems on metal ion-catalyzed oxidation of LDL to malondialdehyde (MDA) and to protein carbonyl and MetO derivatives. Our results revealed that LDL oxidation in mixtures containing free iron or heme derivatives was much greater in bicarbonate/CO2 compared with phosphate buffer. However, when copper was substituted for iron in these mixtures, the rate of LDL oxidation in both buffers was similar. Iron-catalyzed oxidation of LDL was highly sensitive to inhibition by phosphate. Presence of 0.3-0.5 mM phosphate, characteristic of human serum, led to 30-40% inhibition of LDL oxidation in bicarbonate/CO2 buffer. Iron-catalyzed oxidation of LDL to MDA in phosphate buffer was inhibited by increasing concentrations of albumin (10-200 ?M), whereas MDA formation in bicarbonate/CO2 buffer was stimulated by 10-50 ?M albumin but inhibited by higher concentrations. However, albumin stimulated the oxidation of LDL proteins to carbonyl derivatives at all concentrations examined in both buffers. Conversion of LDL to MDA in bicarbonate/CO2 buffer was greatly stimulated by ADP, ATP, and EDTA but only when EDTA was added at a concentration equal to that of iron. At higher than stoichiometric concentrations, EDTA prevented oxidation of LDL. Results of these studies suggest that interactions between bicarbonate and iron or heme derivatives leads to complexes with redox potentials that favor the generation of reactive oxygen species and/or to the generation of highly reactive CO2 anion or bicarbonate radical that facilitates LDL oxidation. Freely available online through the PNAS open access option.Abbreviations: LDL, low-density lipoprotein; MDA, malondialdehyde; MetO, methionine sulfoxide.

Arai, Hirofumi; Berlett, Barbara S.; Chock, P. Boon; Stadtman, Earl R.



Studies on epitopes on low-density lipoprotein modified by 4-hydroxynonenal. Biochemical characterization and determination.  


Oxidation of human low-density lipoprotein (LDL) was found to be accompanied by the generation of various reactive aldehydes. One of them, 4-hydroxynonenal (HNE), was shown to modify LDL to a form which represents a good model of oxidized LDL (ox-LDL). In order to investigate the epitopes newly formed on HNE-modified LDL, a polyvalent antiserum to HNE-LDL [anti-(HNE-LDL)] was raised in rabbits and the non-specific components were removed with native LDL coupled to CNBr-Sepharose 4B. Competitive fluorescence immunoassay analysis showed that anti-(HNE-LDL) recognized HNE-LDL, copper-oxidized LDL, HNE-albumin and to a lower extent HNE-modified high-density lipoprotein 3 (HNE-HDL3) and ox-HDL3 but not native LDL. A certain degree of cross-reactivity of the antibody with LDLs modified by either hexanal or 2,4-heptadienal was found. No reaction was obtained with LDL labelled with malondialdehyde. From the abilities of HNE-modified poly(L-amino acids) to compete with HNE-LDL for binding to anti-(HNE-LDL), it is postulated that lysine, tyrosine, arginine and histidine are involved in the formation of HNE-derived epitopes on apolipoprotein B (apo B). Using a double-sandwich fluorescence immunoassay [capture antibody: anti-(apo B); detection antibody: anti-(HNE-LDL)] we found that the HNE-derived epitopes were expressed at a far higher degree in ox-LDL and HNE-LDL than in native LDL. PMID:1280111

Chen, Q; Esterbauer, H; Jürgens, G



Flow-cytometric determination of high-density-lipoprotein binding sites on human leukocytes  

SciTech Connect

In this method, leukocytes were isolated from 6 mL of EDTA-blood by density-gradient centrifugation and subsequently incubated with rhodamine isothiocyanate (RITC)-conjugated high-density lipoproteins (HDL). The receptor-bound conjugate particles were determined by fluorescent flow cytometry and compared with /sup 125/I-labeled HDL binding data for the same cells. Human granulocytes express the highest number of HDL binding sites (9.4 x 10(4)/cell), followed by monocytes (7.3 x 10(4)/cell) and lymphocytes (4.0 x 10(4)/cell). Compared with conventional analysis of binding of /sup 125/I-labeled HDL in tissue-culture dishes, the present determination revealed significantly lower values for nonspecific binding. In competition studies, the conjugate competes for the same binding sites as /sup 125/I-labeled HDL. With the use of tetranitromethane-treated HDL3, which fails to compete for the HDL receptor sites while nonspecific binding is not affected, we could clearly distinguish between 37 degrees C surface binding and specific 37 degrees C uptake of RITC-HDL3, confirming that the HDL receptor leads bound HDL particles into an intracellular pathway rather than acting as a docking type of receptor. Patients with familial dysbetalipoproteinemia showed a significantly higher number of HDL binding sites in the granulocyte population but normal in lymphocytes and monocytes, indicating increased uptake of cholesterol-containing lipoproteins. In patients with familial hypercholesterolemia, HDL binding was increased in all three cell types, indicating increased cholesterol uptake and increased cholesterol synthesis. The present method allows rapid determination of HDL binding sites in leukocytes from patients with various forms of hyper- and dyslipoproteinemias.

Schmitz, G.; Wulf, G.; Bruening, T.A.; Assmann, G.



Low-Density Lipoprotein Electronegativity Is a Novel Cardiometabolic Risk Factor  

PubMed Central

Background Low-density lipoprotein (LDL) plays a central role in cardiovascular disease (CVD) development. In LDL chromatographically resolved according to charge, the most electronegative subfraction–L5–is the only subfraction that induces atherogenic responses in cultured vascular cells. Furthermore, increasing evidence has shown that plasma L5 levels are elevated in individuals with high cardiovascular risk. We hypothesized that LDL electronegativity is a novel index for predicting CVD. Methods In 30 asymptomatic individuals with metabolic syndrome (MetS) and 27 healthy control subjects, we examined correlations between plasma L5 levels and the number of MetS criteria fulfilled, CVD risk factors, and CVD risk according to the Framingham risk score. Results L5 levels were significantly higher in MetS subjects than in control subjects (21.9±18.7 mg/dL vs. 11.2±10.7 mg/dL, P:0.01). The Jonckheere trend test revealed that the percent L5 of total LDL (L5%) and L5 concentration increased with the number of MetS criteria (P<0.001). L5% correlated with classic CVD risk factors, including waist circumference, body mass index, waist-to-height ratio, smoking status, blood pressure, and levels of fasting plasma glucose, triglyceride, and high-density lipoprotein. Stepwise regression analysis revealed that fasting plasma glucose level and body mass index contributed to 28% of L5% variance. The L5 concentration was associated with CVD risk and contributed to 11% of 30-year general CVD risk variance when controlling the variance of waist circumference. Conclusion Our findings show that LDL electronegativity was associated with multiple CVD risk factors and CVD risk, suggesting that the LDL electronegativity index may have the potential to be a novel index for predicting CVD. Large-scale clinical trials are warranted to test the reliability of this hypothesis and the clinical importance of the LDL electronegativity index. PMID:25203525

Lu, Jonathan; Chen, Shu-Hua; Chen, Fang-Yu; Chen, Ching-Chu; Chen, Jeffrey L.; Elayda, MacArthur; Ballantyne, Christie M.; Shayani, Steven; Chen, Chu-Huang



Theoretical Prediction of Low-Density Lipoproteins Concentration at the Luminal Surface of an Artery with a Multiple Bend  

Microsoft Academic Search

To elucidate the mechanisms of localization of atherosclerotic lesions in man, the effects of various physical and hemodynamic factors on transport of atherogenic low-density lipoproteins (LDL) from flowing blood to the wall of an artery with a multiple bend were studied theoretically by means of a computer simulation under the conditions of a steady flow. It was found that due

Shigeo Wada; Takeshi Karino



Intracellular transport of low density lipoprotein-derived cholesterol is defective in Niemann-Pick type C fibroblasts  

Microsoft Academic Search

Niemann-Pick disease type C (NPC) is characterized by substantial intracellular accumulation of unesterified cholesterol. The accumulation of unesterified cholesterol in NPC fibroblasts cultured with low density lipoprotein (LDL) appears to result from the inability of LDL to stimulate cholesterol esterification in addition to impaired LDL-mediated downregulation of LDL receptor activity and cellular cholesterol synthesis. Although a defect in cholesterol transport

Laura Liscum; Regina M. Ruggiero; Jerry R. Faust



Efficacy of Low-Density Lipoprotein Apheresis in Patients with Peripheral Arterial Occlusive Disease Undergoing Hemodialysis Treatment  

Microsoft Academic Search

Background: Low-density lipoprotein (LDL) apheresis is effective in the treatment of peripheral arterial occlusive disease (PAOD). In the present study, we attempted to determine whether LDL apheresis is effective even for PAOD patients undergoing hemodialysis, who tend to be refractory to any treatment, and if so, to determine the mechanism of its efficacy. Methods: Serum levels of lipids and vascular

Satoshi Morimoto; Yutaka Yano; Kei Maki; Katsunori Sawada; Toshiji Iwasaka



Genetic variation at the PCSK9 locus, low density lipoproteins, response to pravastatin and coronary heart disease: results from PROSPER  

Technology Transfer Automated Retrieval System (TEKTRAN)

Caucasian carriers of the T allele at R46L in the proprotein convertase subtilisin/kexin type 9 (PCSK9) locus have been reported to have 15% lower low-density lipoprotein (LDL) cholesterol (C) levels and 47% lower coronary heart disease (CHD) risk. Our objective was to examine two PCSK9 single nucle...


Effects of Vitamin E and Volatile Oils on the Susceptibility of Low-Density Lipoprotein to Oxidative Modification  

Microsoft Academic Search

Antioxidant consumption has been reported to be inversely associated with the incidence of coronary artery disease. To clarify the possible role of vitamin E and volatile oils in the prevention of atherosclerosis, the effects of these compounds on the susceptibility of low-density lipoprotein (LDL) to oxidative modification were investigated. In this study, vitamin E and seven volatile oils \\

Mohammad Reza Safari



Expression of human apolipoprotein A-I epitopes in high density lipoproteins and in serum  

SciTech Connect

The expression and immunoreactivity of apolipoprotein (apo) A-I epitopes in high density lipoproteins (HDL) and serum has been investigated using two series of monoclonal antibodies (Mabs) which have been described elsewhere. Series 1 Mabs, identified as 3D4, 6B8, and 5G6, were obtained by immunization and screening with apoA-I, and series 2 Mabs, identified as 2F1, 4H1, 3G10, 4F7, and 5F6, were obtained by immunization and screening with HDL. These Mabs were characterized with respect to their binding to HDL particles in solution. In series 2 Mabs, 2F1, 3G10, and 4F7, which react with apoA-I CNBr-fragments 1 and 2, could precipitate 100% of /sup 125/I-labeled HDL, while 4H1 and 5F6, which react with CNBr fragments 1 and 3, precipitated 90 and 60% of /sup 125/I-labeled HDL, respectively. Therefore, three distinct epitopes mapped to CNBr fragments 1 and 2 have been identified which are expressed on all HDL particles, indicating that several antigenic do mains exist on apoA-I which have the same conformation on all apoA-I-containing lipoproteins. The Mabs reacting at these sites have significantly higher affinity constants for /sup 125/I-labeled HDL than those that failed to precipitate 100% of HDL. This suggests that the high affinity Mabs react with apoA-I epitopes that are both expressed on all lipoproteins and located in thermo-dynamically stable regions of the molecules. All Mabs from series 1 precipitated 35% or less of /sup 125/I-labeled HDL prepared from freshly collected serum, but the proportion of HDL particles expressing the epitopes for these Mabs doubled or more upon serum storage at 4 degrees C. The time course of the alteration of apoA-I antigen in vitro was measured in three normolipemic donors.

Marcel, Y.L.; Jewer, D.; Vezina, C.; Milthorp, P.; Weech, P.K.



PFOS induced lipid metabolism disturbances in BALB/c mice through inhibition of low density lipoproteins excretion  

NASA Astrophysics Data System (ADS)

Male BALB/c mice fed with either a regular or high fat diet were exposed to 0, 5 or 20 mg/kg perfluorooctane sulfonate (PFOS) for 14 days. Increased body weight, serum glucose, cholesterol and lipoprotein levels were observed in mice given a high fat diet. However, all PFOS-treated mice got reduced levels of serum lipid and lipoprotein. Decreasing liver glycogen content was also observed, accompanied by reduced serum glucose levels. Histological and ultrastructural examination detected more lipid droplets accumulated in hepatocytes after PFOS exposure. Moreover, transcripitonal activity of lipid metabolism related genes suggests that PFOS toxicity is probably unrelevant to PPAR?'s transcription. The present study demonstrates a lipid disturbance caused by PFOS and thus point to its role in inhibiting the secretion and normal function of low density lipoproteins.

Wang, Ling; Wang, Yu; Liang, Yong; Li, Jia; Liu, Yuchen; Zhang, Jie; Zhang, Aiqian; Fu, Jianjie; Jiang, Guibin



PFOS induced lipid metabolism disturbances in BALB/c mice through inhibition of low density lipoproteins excretion.  


Male BALB/c mice fed with either a regular or high fat diet were exposed to 0, 5 or 20 mg/kg perfluorooctane sulfonate (PFOS) for 14 days. Increased body weight, serum glucose, cholesterol and lipoprotein levels were observed in mice given a high fat diet. However, all PFOS-treated mice got reduced levels of serum lipid and lipoprotein. Decreasing liver glycogen content was also observed, accompanied by reduced serum glucose levels. Histological and ultrastructural examination detected more lipid droplets accumulated in hepatocytes after PFOS exposure. Moreover, transcripitonal activity of lipid metabolism related genes suggests that PFOS toxicity is probably unrelevant to PPAR?'s transcription. The present study demonstrates a lipid disturbance caused by PFOS and thus point to its role in inhibiting the secretion and normal function of low density lipoproteins. PMID:24694979

Wang, Ling; Wang, Yu; Liang, Yong; Li, Jia; Liu, Yuchen; Zhang, Jie; Zhang, Aiqian; Fu, Jianjie; Jiang, Guibin



Collagenase-3 binds to a specific receptor and requires the low density lipoprotein receptor-related protein for internalization  

NASA Technical Reports Server (NTRS)

We have previously identified a specific receptor for collagenase-3 that mediates the binding, internalization, and degradation of this ligand in UMR 106-01 rat osteoblastic osteosarcoma cells. In the present study, we show that collagenase-3 binding is calcium-dependent and occurs in a variety of cell types, including osteoblastic and fibroblastic cells. We also present evidence supporting a two-step mechanism of collagenase-3 binding and internalization involving both a specific collagenase-3 receptor and the low density lipoprotein receptor-related protein. Ligand blot analysis shows that (125)I-collagenase-3 binds specifically to two proteins ( approximately 170 kDa and approximately 600 kDa) present in UMR 106-01 cells. Western blotting identified the 600-kDa protein as the low density lipoprotein receptor-related protein. Our data suggest that the 170-kDa protein is a specific collagenase-3 receptor. Low density lipoprotein receptor-related protein-null mouse embryo fibroblasts bind but fail to internalize collagenase-3, whereas UMR 106-01 and wild-type mouse embryo fibroblasts bind and internalize collagenase-3. Internalization, but not binding, is inhibited by the 39-kDa receptor-associated protein. We conclude that the internalization of collagenase-3 requires the participation of the low density lipoprotein receptor-related protein and propose a model in which the cell surface interaction of this ligand requires a sequential contribution from two receptors, with the collagenase-3 receptor acting as a high affinity primary binding site and the low density lipoprotein receptor-related protein mediating internalization.

Barmina, O. Y.; Walling, H. W.; Fiacco, G. J.; Freije, J. M.; Lopez-Otin, C.; Jeffrey, J. J.; Partridge, N. C.



[A history and review of cholesterol ester transfer protein inhibitors and their contribution to the understanding of the physiology and pathophysiology of high density lipoprotein].  


There is irrefutable evidence that statins reduce the risk of cardiovascular events in a magnitude proportional to the intensity of the decrease in cholesterol transport by the low density lipoproteins. Despite this great advance there is still a residual risk of cardiovascular events. For this reason, an increase in the levels of high density lipoprotein is considered in order to boost the main action of this lipoprotein, which is reverse cholesterol transport. Distinct classes of evidence (epidemiological, genetic, and pathophysiological) show that the inhibition and/or modulation of cholesterol ester transfer protein increases plasma high density lipoprotein-cholesterol levels. The main reason for presenting this review is to look at the physiology of cholesterol ester transfer protein, its interrelationship with high density lipoproteins, and to give an update on the development of different cholesterol ester transfer protein inhibitor/modulator molecules. PMID:24094503

Corral, Pablo; Schreier, Laura



The binding of animal low-density lipoproteins to human apolipoprotein(a).  

PubMed Central

Lipoprotein(a) [Lp(a)] is a risk factor for coronary artery disease. It is composed of lipids and apolipoprotein(a) [apo(a)] linked to apolipoprotein B (apoB) by a disulphide bond between Cys-4057 of apo(a)'s kringle 36 and possibly Cys-3734 of apoB. We call this the covalent apo(a): apoB-Lp interaction, to distinguish it from the non-covalent apo(a)/Lp(a): apoB-Lp interaction, which is probably mediated by apo(a)'s kringle 33 and residues 3304-3317 of apoB. The non-covalent interaction could be the initial interaction which brings apo(a) and apoB together prior to covalent linkage and Lp(a) formation. The non-covalent apo(a)/Lp(a)-binding site on apoB is evolutionarily more ancient than the covalent apo(a)-binding site on apoB. Both human and non-human low-density lipoproteins (LDLs) bind non-covalently to human apo(a)/Lp(a); however, only rabbit and human LDLs bind covalently to human apo(a). The non-covalent interaction between mouse LDL and human apo(a)/Lp(a) has a Kd of (1.7 +/- 1.33) x 10(-7) M (n = 3). This explains the co-localization of human apo(a) and mouse apoB in the atherosclerotic lesions of human apo(a) transgenic mice and supports our hypothesis that the non-covalent interaction is a contributing factor to apo(a) atherogenicity. Images Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:7639708

Trieu, V N; McConathy, W J



The interaction between human low density lipoproteins and bovine aortic endothelial cells. Measurements of membrane fluidity.  


Bovine aortic endothelial cells in culture have been incubated with human low density lipoproteins (LDL) characterized in their cholesterol content. The incubation was done at different time intervals up to 72 h and various LDL concentrations. It began after endothelial cells had been starved for 24 h in lipoprotein deficient serum. The transfer of some LDL-components to endothelial cells plasmalemma was monitored by measurements of membrane fluidity. Namely, the fluorescent probe trimethylamonio-diphenyl hexatriene was inserted in the cell membrane and fluorescence anisotropy was determined; a higher fluorescence anisotropy means a higher rigidity of the plasmalemma. The results show that the rigidity of the endothelial cell plasmalemma increased progressively with the time of incubation (+11% to +19.5% after 24 h and 72 h, respectively for the concentration of 200 micrograms. LDL-cholesterol/dish) and with the greater amount of cholesterol in LDL (+10.9%) for 200 micrograms LDL-cholesterol/dish to +15% for 800 micrograms LDL-cholesterol/dish after 24 h incubation). In order to see if the LDL material transfer proceeded by receptor-mediated endocytosis of LDL and/or directly through aqueous solution a lysosomal inhibitor, chloroquine, was used at the concentration of 20 microM for preventing the lysosomal hydrolase activity. In the presence of this inhibitor the fluorescence anisotropy in treated endothelial cells increased by a lesser amount, suggesting an approx. 30% participation of intracellular route. Therefore, the transfer of material (probably cholesterol) from LDL to endothelial plasmalemma could take place both by receptor-mediated endocytosis and directly through the aqueous solution. PMID:2510195

Badea, M G; Sima, A; Jinga, V V; Hörer, O



Oxidized Low Density Lipoprotein (LDL) Affects Hyaluronan Synthesis in Human Aortic Smooth Muscle Cells*  

PubMed Central

Thickening of the vessel in response to high low density lipoprotein(s) (LDL) levels is a hallmark of atherosclerosis, characterized by increased hyaluronan (HA) deposition in the neointima. Human native LDL trapped within the arterial wall undergoes modifications such as oxidation (oxLDL). The aim of our study is to elucidate the link between internalization of oxLDL and HA production in vitro, using human aortic smooth muscle cells. LDL were used at an effective protein concentration of 20–50 ?g/ml, which allowed 80% cell viability. HA content in the medium of untreated cells was 28.9 ± 3.7 nmol HA-disaccharide/cell and increased after oxLDL treatment to 53.9 ± 5.6. OxLDL treatments doubled the transcripts of HA synthase HAS2 and HAS3. Accumulated HA stimulated migration of aortic smooth muscle cells and monocyte adhesiveness to extracellular matrix. The effects induced by oxLDL were inhibited by blocking LOX-1 scavenger receptor with a specific antibody (10 ?g/ml). The cholesterol moiety of LDL has an important role in HA accumulation because cholesterol-free oxLDL failed to induce HA synthesis. Nevertheless, cholesterol-free oxLDL and unmodified cholesterol (20 ?g/ml) induce only HAS3 transcription, whereas 22,oxysterol affects both HAS2 and HAS3. Moreover, HA deposition was associated with higher expression of endoplasmic reticulum stress markers (CHOP and GRP78). Our data suggest that HA synthesis can be induced in response to specific oxidized sterol-related species delivered through oxLDL. PMID:23979132

Viola, Manuela; Bartolini, Barbara; Vigetti, Davide; Karousou, Evgenia; Moretto, Paola; Deleonibus, Sara; Sawamura, Tatsuya; Wight, Thomas N.; Hascall, Vincent C.; De Luca, Giancarlo; Passi, Alberto



Pharmacogenetic Predictors of Statin-Mediated Low-Density Lipoprotein Cholesterol Reduction and Dose Response  

PubMed Central

Background There is interindividual variation in low-density lipoprotein cholesterol (LDLc) lowering by statins and limited study into the genetic associations of the dose dependant LDLc lowering by statins. Methods and Results Five hundred nine patients with hyperlipidemia were randomly assigned atorvastatin 10 mg, simvastatin 20 mg, or pravastatin 10 mg (low-dose phase) followed by 80 mg, 80 mg, and 40 mg (high-dose phase), respectively. Thirty-one genes in statin, cholesterol, and lipoprotein metabolism were sequenced and 489 single nucleotide polymorphisms with minor allele frequencies >2% were tested for associations with percentage LDLc lowering at low doses using multivariable adjusted general linear regression. Significant associations from the analysis at low dose were then repeated at high-dose statins. At low doses, only 1 single nucleotide polymorphism met our experiment-wide significance level, ABCA1 rs12003906. Twenty-six subjects carried the minor allele of rs12003906, which was associated with an attenuated LDLc reduction (LDLc reduction in carriers versus noncarriers ?24.1±2.6% versus ?32.2±1.5%; P=0.0001). In addition, we replicated the association with the APOE ?3 allele and a reduced LDLc reduction. At high doses, carriers of the minor allele of ABCA1 rs12003906 and the APOE ?3 allele improved their LDLc reduction but continued to have a diminished LDLc reduction compared with noncarriers (?30.5±4.0% versus ?42.0±2.4%; P=0.005) and (?38.5±1.9% versus ?45.3±2.8%; P=0.009), respectively. Conclusions An intronic single nucleotide polymorphism in ABCA1 and the APOE ?3 allele are associated with reduced LDLc lowering by statins and identify individuals who may be resistant to maximal LDLc lowering by statins. PMID:20031551

Voora, Deepak; Shah, Svati H.; Reed, Carol R.; Zhai, Jun; Crosslin, David R.; Messer, Chad; Salisbury, Benjamin A.; Ginsburg, Geoffrey S.



Modification of High Density Lipoprotein by Myeloperoxidase Generates a Pro-inflammatory Particle*  

PubMed Central

High density lipoprotein (HDL) is the major atheroprotective particle in plasma. Recent studies demonstrate that myeloperoxidase (MPO) binds to HDL in vivo, selectively targeting apolipoprotein A1 (apoA1) of HDL for oxidative modification and concurrent loss in cholesterol efflux and lecithin cholesterol acyl transferase activating activities, generating a “dysfunctional HDL” particle. We now show that (patho)physiologically relevant levels of MPO-catalyzed oxidation result in loss of non-cholesterol efflux activities of HDL including anti-apoptotic and anti-inflammatory functions. One mechanism responsible is shown to involve the loss of modified HDL binding to the HDL receptor, scavenger receptor B1, and concurrent acquisition of saturable and specific binding to a novel unknown receptor independent of scavenger receptors CD36 and SR-A1. HDL modification by MPO is further shown to confer pro-inflammatory gain of function activities as monitored by NF-?B activation and surface vascular cell adhesion molecule levels on aortic endothelial cells exposed to MPO-oxidized HDL. The loss of non-cholesterol efflux activities and the gain of pro-inflammatory functions requires modification of the entire particle and can be recapitulated by oxidation of reconstituted HDL particles comprised of apoA1 and nonoxidizable phosphatidylcholine species. Multiple site-directed mutagenesis studies of apoA1 suggest that the pro-inflammatory activity of MPO-modified HDL does not involve methionine, tyrosine, or tryptophan, oxidant-sensitive residues previously mapped as sites of apoA1 oxidation within human atheroma. Thus, MPO-catalyzed oxidation of HDL results not only in the loss of classic atheroprotective reverse cholesterol transport activities of the lipoprotein but also both the loss of non-cholesterol efflux related activities and the gain of pro-inflammatory functions. PMID:19726691

Undurti, Arundhati; Huang, Ying; Lupica, Joseph A.; Smith, Jonathan D.; DiDonato, Joseph A.; Hazen, Stanley L.



Studies on the production of low density lipoproteins by perfused livers from nonhuman primates. Effect of dietary cholesterol.  

PubMed Central

Nonhuman primates consuming diets containing cholesterol develop coronary artery atherosclerosis that we have found to be highly correlated with an increase in the size and cholesteryl ester content of plasma low density lipoproteins (LDL). The present studies were designed to determine whether the enlarged plasma LDL are produced directly by the liver of cholesterol-fed monkeys. African green monkeys were fed a diet containing 40% of calories as butter fat and either 0.16 mg cholesterol/kcal (control diet) or 0.78 mg cholesterol/kcal (test diet). The livers of these monkeys were perfused by recirculation with a lipoprotein-free medium for 4 h. The rate of accumulation of perfusate cholesterol was linear and greater in liver perfusates from test diet-fed vs. control diet-fed monkeys and was positively correlated with both the plasma cholesterol concentration and LDL size in the donor animal. All perfusate d less than 1.063 g/ml lipoprotein subfractions from livers of test diet-fed monkeys were enriched in cholesteryl ester severalfold over the corresponding subfractions from control diet-fed monkeys and contained only the larger form of apolipoprotein B typical of plasma LDL. However, the perfusate lipoproteins in the LDL density range did not have an average size or composition typical of LDL from plasma. Rather, they were relatively enriched in phospholipid and unesterified cholesterol and were deficient in cholesteryl esters. In addition, perfusate high density lipoproteins were discoidal particles. These data show that the enzyme lecithin:cholesterol acyltransferase (LCAT) was essentially inactive in these perfusates and, as a result, the dietary cholesterol-induced enrichment of perfusate d less than 1.063 g/ml lipoproteins with cholesteryl esters probably resulted from increased hepatic secretion of cholesteryl esters and not from modification of lipoproteins by LCAT during recirculating perfusion. In spite of this increase, enlarged cholesteryl ester-rich LDL were not found in the perfusate, suggesting that large molecular weight plasma LDL are not directly secreted by the liver but instead probably result from further intravascular metabolism of cholesteryl ester-enriched hepatic precursor lipoproteins. Images FIGURE 2 FIGURE 6 FIGURE 8 PMID:6874948

Johnson, F L; St Clair, R W; Rudel, L L



Cloning of monoclonal autoantibodies to epitopes of oxidized lipoproteins from apolipoprotein E-deficient mice. Demonstration of epitopes of oxidized low density lipoprotein in human plasma.  

PubMed Central

Many reactive products may be formed when LDL undergoes lipid peroxidation, which in turn can react with lipids, apoproteins, and proteins, generating immunogenic neoepitopes. Autoantibodies recognizing model epitopes of oxidized low density lipoprotein, such as malondialdehydelysine, occur in plasma and in atherosclerotic lesions of humans and animals. Because apo E-deficient mice develop particularly high titers of such autoantibodies, we used their spleens to clone 13 monoclonal antibodies to various epitopes of oxidized LDL ("E0 antibodies"). Binding and competitive RIAs demonstrated significant differences in fine specificity even between E0 antibodies initially selected for binding to the same screening antigen. For example, some E0 antibodies selected for binding to malondialdehyde-LDL also recognized copper oxidized LDL, acrolein-LDL, or LDL modified by arachidonic or linoleic acid oxidation products. Circulating IgG and IgM autoantibodies binding to copper-oxidized LDL, 4-hydroxynonenal-LDL, acrolein-LDL, and LDL modified with arachidonic or linoleic acid oxidation products were found in apo E-deficient mice, suggesting that the respective antigens are formed in vivo. Epitopes recognized by some of the E0 monoclonal antibodies were also found on human circulating LDL. Each of the E0 monoclonal antibodies immunostained rabbit and human atherosclerotic lesions, and some of them yielded distinct staining patterns in advanced lesions. Together, this suggests that the natural monoclonal antibodies recognize different epitopes of complex structures formed during oxidation of lipoproteins, or epitopes formed independently at different lesion sites. Our data demonstrate that a profound immunological response to a large number of different epitopes of oxidized lipoproteins occurs in vivo. The availability of "natural" monoclonal autoantibodies should facilitate the identification of specific epitopes inducing this response. PMID:8698873

Palinski, W; Hörkkö, S; Miller, E; Steinbrecher, U P; Powell, H C; Curtiss, L K; Witztum, J L



Familial defective apolipoprotein B-100: low density lipoproteins with abnormal receptor binding  

SciTech Connect

Previous in vivo turnover studies suggested that retarded clearance of low density lipoproteins (LDL) from the plasma of some hypercholesterolemic patients is due to LDL with defective receptor binding. The present study examined this postulate directly by receptor binding experiments. The LDL from a hypercholesterolemic patient (G.R.) displayed a reduced ability to bind to the LDL receptors on normal human fibroblasts. The G.R. LDL possessed 32% of normal receptor binding activity. Likewise, the G.R. LDL were much less effective than normal LDL in competing with /sup 125/I-labeled normal LDL for cellular uptake and degradation and in stimulating intracellular cholesteryl ester synthesis. The defect in LDL binding appears to be due to a genetic abnormality of apolipoprotein B-100: two brothers of the proband possess LDL defective in receptor binding, whereas a third brother and the proband's son have normally binding LDL. Further, the defect in receptor binding does not appear to be associated wit an abnormal lipid composition or structure of the LDL. Normal and abnormal LDL subpopulations were partially separated from plasma of two subjects by density-gradient ultracentrifugation, a finding consistent with the presence of a normal and a mutant allele. The affected family members appear to be heterozygous for this disorder, which has been designated familial defective apolipoprotein B-100. These studies indicate that the defective receptor binding results in inefficient clearance of LDL and the hypercholesterolemia observed in these patients.

Innerarity, T.L.; Weisgraber, K.H.; Arnold, K.S.; Mahley, R.W.; Krauss, R.M.; Vega, G.L.; Grundy, S.M.



Low-density lipoprotein apheresis for prevention and regression of atherosclerosis: clinical results.  


Hypercholesterolemia can be adequately controlled by appropriate diet and maximum lipid lowering drug therapy in most patients. Nevertheless, there exists a group of patients, including those with familial hypercholesterolemia (FH), who remain at high risk for the development or progression of premature coronary heart disease (CHD). For these patients additional measures such as surgery and low-density lipoprotein (LDL) apheresis have to be considered. The objective of this multicenter trial, which included 30 clinical centers (28 in Germany and one each in Scotland and Luxembourg), was to determine if repeated LDL apheresis using the Liposorber LA-15 system (Kaneka Corporation, Osaka, Japan) could lead to an additional acute and time averaged lowering of total cholesterol (TC) and LDL-cholesterol (LDL-C) in severely hypercholesterolemic patients whose cholesterol levels could not be controlled by appropriate diet and maximum drug therapy. A total of 6,798 treatments were performed on 120 patients, including 8 with homozygous FH, 75 with heterozygous FH, and 37 with unclassified FH or other hyperlipidemias from 1988 through 1994. The mean TC and mean LDL-C levels at baseline were 410.0 mg/dl and 333.9 mg/dl, respectively. LDL apheresis was performed once a week or at least once every 2 weeks in all patients. During treatment with the Liposorber system the mean acute percentage reduction was 52.6% for TC and 63.1% for LDL-C. Very low density lipoprotein cholesterol (VLDL-C) and triglycerides (TG) were also substantially reduced to 60.6% and 47.5%, respectively. Fibrinogen, a potential risk factor for CHD, was reduced by 26.2%. In contrast, the mean acute reduction of high density lipoprotein (HDL) was only 3.4%. During the course of the treatment, the time averaged levels of TC and LDL-C were reduced by approximately 39% and 50%, respectively, compared to baseline levels. The adverse events (AEs) were those generally associated with extracorporeal treatments. The most common AE was hypotension, with 69 episodes corresponding to 1% of all treatments reported in 44 of the 120 patients treated. All other kinds of AEs occurred in less than 0.2% of the treatments. The treatment with the Liposorber LA-15 system was overall well tolerated. It should be noted, however, that a more severe type of hypotensive reaction associated with flush, bradycardia, and dyspnea was reported in patients taking concomitant angiotensin converting enzyme (ACE) inhibitor medication. Except for such anaphylactoid-like reactions associated with the intake of ACE inhibitors, the Liposorber LA-15 system represents a safe and effective therapeutic option for patients suffering from severe hypercholesterolemia that could not be adequately controlled by diet and maximum drug therapy. PMID:10225746

Bambauer, R; Olbricht, C J; Schoeppe, E



Synthesis of very low density lipoproteins in the cockerel. Effects of estrogen.  

PubMed Central

The effect of estrogen on the synthesis of plasma very low density lipoproteins (VLDL) in the cockerel was studied both in vivo and in vitro. Synthesis was studied by immunoprecipitation techniques with antisera prepared against VLDL and a major VLDL protein. VLDL were isolated from the plasma of white Leghorn hens and estrogen-treated white Leghorn cockerels by ultracentrifugal flotation at d 1.006 g/ml. After delipidation, the lipid-free proteins (apoproteins) were fractionated on Sephadex G-150 and DEAE-cellulose. Both the hen and the estrogen-treated cockerel VLDL were shown to contain an identical apoprotein with a mol wt of approximately 12,000; the apoprotein is designated fraction B. Reduction and S-carboxy-methylation of fraction B resulted in a reduction of the molecular weight by approximately one-half, indicating a dimer-monomer relationship. Antiserum prepared to the hen VLDL dimer protein gave precipitin lines of complete identity to both the hen and cockerel dimer, monomer, VLDL, apoVLDL, low density lipoproteins, and plasma; no precipitin line was formed with either hen or cockerel high density lipoproteins. After a single subcutaneous injection of diethylstilbestrol into the cockerel, plasma VLDL protein, cholesterol, and triglyceride increased, reaching a maximum 24--48 h after hormone administration. Liver slices from similarly treated animals were incubated in vitro in culture medium in the presence of [3H]lysine for 2 h. Immunoprecipitable radioactivity in VLDL increased within 2 h of diethylstilbestrol treatment and reached a maximum at 24 h; VLDL radioactivity returned to base-line levels by 72 h. At the peak of induction, newly synthesized VLDL represented 11% of the total soluble protein synthesized. When actinomycin-D (5 mg/kg) was administered simultaneously with estrogen, the induction of VLDL synthesis was totally inhibited. To determine whether the effect of estrogen on VLDL synthesis was mediated at the level of transcription, partially-purified cockerel liver mRNA was prepared from estrogen-treated animals and the mRNA activity for fraction B was quantitated in a wheat germ translation system. Fraction B mRNA was found to increase from a low base-line value to a maximum 16-24 h after estrogen treatment, returning towards baseline values at 30 h. At the peak of induction, fraction B constituted 12% of the total protein synthesized. The kinetics of induction of fraction B mRNA activity in the cell-free translation system is very similar to that observed in liver slice experiments. This finding suggests that estrogen stimulates VLDL synthesis, at least partially, by enhancing the accumulation of the mRNA for one of their major apoproteins. Images PMID:182719

Chan, L; Jackson, R L; O'Malley, B W; Means, A R



Characterization of the structure of polydisperse human low-density lipoprotein by neutron scattering.  

PubMed Central

Low-density lipoproteins (LDL) in plasma are constructed from a single molecule of apolipoprotein B-100 (M(r) 512000) in association with lipid (approximate M(r) 2-3 x 10(6)). The gross structure was studied using an updated pulsed-neutron camera LOQ with an area detector to establish the basis for the interpretation of structural changes seen during dynamic studies of LDL oxidation. Neutron-scattering data for LDL in 100% 2H2O buffers emphasize their external appearance. Guinier analysis on a continuous-flux neutron camera D17 revealed pronounced concentration-dependences in the radius of gyration, RG, and the intensity of forward scattering, I(0) (equivalent to the M(r) of LDL) between 0.5 and 11 mg of LDL protein/ml. LDL preparations from different donors gave different RG values. When extrapolated to zero concentration, RG values ranged between 8.3 and 10.6 nm and were linearly correlated with M(r), which is consistent with a spherical structure. The distance-distribution function P(r) in real space showed a single maximum at 9.1-10.9 nm, which is just under half the observed maximum dimension of 23.1 +/- 1.2 nm expected for a spherical structure. The neutron radial-density function p(r) exhibited a plateau of high and featureless density at the centre of LDL. LDL can be modelled by a polydisperse assembly of spheres with two internal densities and a mean radius close to 10.0 nm in a normal distribution of radii with a standard deviation of 2.0 nm. The data are consistent with recent electron-microscopy and ultracentrifugation data.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7654176

Meyer, D F; Nealis, A S; Bruckdorfer, K R; Perkins, S J



Interaction of high and low density lipoproteins on glycosaminoglycan secretion by human vascular smooth muscle cells and fibroblasts.  


Low density lipoprotein (LDL) increased secretion of glycosaminoglycans (GAG) and the cell cholesterol content of proliferating fibroblasts and smooth muscle cells in culture; with increasing cell density the GAG effect decreased, but the cholesterol effect did not. High density lipoprotein (HDL, d greater than 1.063) decreased GAG secretion by slowly proliferating cells; when cells were actively proliferating, HDL alone did not affect GAG secretion, but it inhibited the increase caused by LDL. Thus HDL appeared to influence GAG secretion by two separate mechanisms, an inhibition which was overcome by rapid proliferation and an anti-LDL effect. HDL2 (d = 1.063-1.100) partially reproduced the latter effect. In addition, HDL, HDL2, and HDL3 increased cell cholesterol; the ability of LDL to increase cholesterol was correspondingly reduced in the presence of HDL and its subfractions, suggesting that they act by common mechanisms. PMID:6509364

Wosu, L; McCormick, S; Kalant, N



The effect of plasma low density lipoprotein apheresis on the hepatic secretion of biliary lipids in humans  

PubMed Central

Background—The liver is a key organ in the metabolism of cholesterol in humans. It is the only organ by which substantial amounts of cholesterol are excreted from the body, either directly as free cholesterol into the bile or after conversion to bile acids. The major part of cholesterol synthesis in the body occurs in the liver. Cholesterol is also taken up by the liver from plasma lipoproteins. The relative contributions of newly synthesised cholesterol and plasma lipoprotein cholesterol to bile acid synthesis and biliary cholesterol secretion, respectively, are not known in detail. ?Aims—To determine how a rapid lowering of plasma low density lipoprotein (LDL) and very low density lipoprotein (VLDL) cholesterol influences the biliary secretion rates of cholesterol and bile acids in patients with cholesterol gallstones and complete biliary drainage. In this model with a completely interrupted enterohepatic circulation, the secretion of bile acids equals the new synthesis of bile acids in the liver. ?Patients—Eight patients with common bile duct stones of cholesterol type undergoing conventional cholecystectomy and choledocholithotomy. ?Methods—At operation a balloon occludable Foley catheter attached to a T tube was inserted into the bile duct with the balloon placed just past the distal limb of the T tube. The T tube was allowed to drain the bile externally. One week after the operation the Foley catheter balloon was inflated, creating complete biliary drainage. Twelve hours following the inflation plasma LDL apheresis was carried out for two hours. Bile was collected for 15 minute periods starting one hour before the apheresis and ending two hours after its termination. During the collection of bile, plasma lipids were analysed on several occasions. ?Results—The plasma level of LDL cholesterol decreased by 26% from (mean (SEM)) 2.19 (0.29) to 1.63 (0.17) mmol/l during the LDL apheresis while high density lipoprotein (HDL) cholesterol in plasma was unaffected. During LDL apheresis apolipoprotein B containing lipoproteins bind to the column, causing a significant decrease of not only plasma LDL but also of VLDL cholesterol. The secretion rate of bile acids decreased significantly by 31% from 131 (38) to 90 (16) µmol/15 minutes (p=0.045). The output of phospholipids also decreased by 19%. The biliary secretion rate of cholesterol was not, however, affected by the plasma LDL apheresis. ?Conclusions—The results suggest that, in patients with cholesterol gallstones and complete biliary drainage, lowering of plasma LDL and VLDL cholesterol reduces the biliary secretion rate—synthesis—of bile acids without affecting the biliary secretion rate of cholesterol. ?? Keywords: bile acids; biliary lipids; cholesterol; lipoproteins; plasma apheresis PMID:9414982

Hillebrant, C; Nyberg, B; Einarsson, K; Eriksson, M



Reduced Serum Levels of Triglyceride, Very Low Density Lipoprotein Cholesterol and Apolipoprotein B in Parkinson’s Disease Patients  

PubMed Central

Background Previous studies have shown a lower incidence of stroke in Parkinson’s disease (PD) patients. The role of the lipids and lipoproteins as risk factors for stroke is uncertain in the lower prevalence of stroke in PD patients. Objectives To explore the lipids and lipoproteins serum levels in PD patients. Methods A retrospective study was performed on 110 PD patients (PD group), 130 controls with non-cerebrovascular neurological diseases (OD group), 140 acute intracerebral hemorrhage patients (ICH group) and 140 acute cerebral infarction patients (CI group). The records about serum levels of lipids and lipoproteins were analyzed. Results There were significant differences for the serum level of triglyceride (F = 5.031, p=0.002), very low density lipoprotein cholesterol (F = 5.313, p=0.001), apolipoprotein B (F = 16.038, p<0.0001) in the four groups. PD group had a significantly lower serum level of triglyceride (TG) than the OD (p=0.032), ICH (p=0.00047) and CI (p=0.001) groups. Very low density lipoprotein cholesterol (VLDL-C) serum level was significantly lower in PD group than in OD (p=0.039), ICH (p=0.00021) and CI (p=0.001) groups. There was a significantly lower serum level of apolipoprotein B (apo B) in PD group than in OD (p=0.002), ICH (p<0.0001) and CI (p<0.0001) groups. Conclusions There are reduced serum levels of TG, VLDL-C and apo B in PD patients, which may be related to the decreased prevalence of stroke in PD patients. PMID:24086623

Tian, Yanghua; Xu, Fangcheng; Chen, Xianwen; Wang, Kai



New insight on the molecular mechanisms of high-density lipoprotein cellular interactions.  


High-density lipoprotein (HDL) cholesterol is an independent negative risk factor for coronary artery disease and thus represents today the only protective factor against atherosclerosis. The protective effect of HDL is mostly attributed to its central function in reverse cholesterol transport (RCT), a process whereby excess cell cholesterol is taken up and processed in HDL particles, and is later delivered to the liver for further metabolism and bile excretion. This process relies on specific interactions between HDL particles and cells, both peripheral (cholesterol efflux) and hepatic (cholesterol disposal) cells, and on the maturation of HDL particles within the vascular compartment. The plasma level of HDL cholesterol will thus result also from the complex interplay with cellular partners. Among them, some contribute to HDL formation - for instance ATP binding cassette AI protein - while others are mostly involved in HDL catabolism, the scavenger receptor-class B type I or the recently described membrane-bound ATP synthase/hydrolase. The last decade has seen major breakthroughs in the identification and elucidation of the role of cellular partners of HDL metabolism, and in their transcriptional regulations, opening up new perspectives in the modulation of HDL cholesterol. PMID:15378205

Martinez, L O; Jacquet, S; Tercé, F; Collet, X; Perret, B; Barbaras, R



Role of leptin on the expression of low density lipoprotein receptor  

PubMed Central

Background & objectives: Leptin resistance oriented hyperleptinaemia is a common problem in obese subjects in association with hypercholesterolaemia. The most common target for hypercholesterolaemia is impaired low density lipoprotein receptor (LDLR). This study was carried out to investigate whether any alteration in LDLR expression could explain the occurrence of hypercholesterolaemia in the event of hyperleptinaemia. Methods: Expression of LDLR and SREBP2 (sterol regulatory element binding protein 2) were examined in HepG2 cells by RT-PCR and Western blotting. JAK2 inhibitor II was used to verify the effect of JAK-STAT (Janus Kinase-Signal Transducer and Activator of Transcription) pathway (common mediator for cytokine signaling). Co-localization of LDLR and insulin receptor (IR) was examined by confocal microscopy. Results: Leptin was found to reduce the expression of LDLR and its transcription factor SREBP2. On the other hand, a weak signal for stimulation of LDLR by leptin was noted to be mediated by JAK2 pathway. But the joint effect of the two signaling pathways kept LDLR only in depressed mode in presence of leptin. Confocal microscopy showed that LDLR made an intensively co-localized complex with insulin receptor in presence of leptin. Interpretation & conclusions: Our results show that though leptin stimulates LDLR expression very weakly through JAK-STAT signaling pathway, it mainly imposes inhibition on LDLR expression by inhibiting transcription factor SREBP2. The inter-association between LDLR and IR may be a reason to render LDLR functionally inactive in presence of leptin. PMID:25488447

Yadav, Naval Kishor; Arjuman, Albina; Chandra, Nimai C.



Low-density lipoprotein-mediated delivery of docosahexaenoic acid selectively kills murine liver cancer cells  

PubMed Central

Aim The natural omega-3 polyunsaturated fatty acid, docosahexaenoic acid (DHA), has recently been credited for possessing anticancer properties. Herein, we investigate the cytotoxic actions of DHA-loaded low-density lipoprotein (LDL) nanoparticles in normal and liver cancer cells. Materials & methods LDL-DHA nanoparticles were prepared and subjected to extensive biophysical characterization. The therapeutic utility of LDL-DHA nanoparticles was evaluated in normal and malignant murine hepatocyte cell lines, TIB-73 and TIB-75, respectively. Results & discussion The engineered LDL-DHA nanoparticles possessed enhanced physical and oxidative stabilities over native LDL and free DHA. Dose–response studies showed that therapeutic doses of LDL-DHA nanoparticles that completely killed TIB-75 were innocuous to TIB-73. The selective induction of lipid peroxidation and reactive oxygen species in the cancer cells was shown to play a central role in LDL-DHA nanoparticle-mediated cytotoxicity. Conclusion In summary, these findings indicate that LDL-DHA nanoparticles show great promise as a selective anticancer agent against hepatocellular carcinoma. PMID:24397600

Reynolds, Lacy; Mulik, Rohit S.; Wen, Xiaodong; Dilip, Archana; Corbin, Ian R.



Ascorbic Acid Prevents Increased Endothelial Permeability Caused by Oxidized Low Density Lipoprotein  

PubMed Central

Mildly oxidized low density lipoprotein (mLDL) acutely increases the permeability of the vascular endothelium to molecules that would not otherwise cross the barrier. We have shown that ascorbic acid tightens the permeability barrier in endothelial barrier in cells, so in this work we tested whether it might prevent the increase in endothelial permeability due to mLDL. Treatment of EA.hy926 endothelial cells with mLDL decreased intracellular GSH and activated the cells to further oxidize the mLDL. mLDL also increased endothelial permeability over 2 h to both inulin and ascorbate in cells cultured on semi-permeable filters. This effect was blocked by microtubule and microfilament inhibitors, but not by chelation of intracellular calcium. Intracellular ascorbate both prevented and reversed the mLDL-induced increase in endothelial permeability, an effect mimicked by other cell-penetrant antioxidants. These results suggest a role for endothelial cell ascorbate in ameliorating an important facet of endothelial dysfunction caused by mLDL. PMID:20815791

May, James M.; Qu, Zhi-chao



Anti-psoriatic therapy recovers high-density lipoprotein composition and function.  


Psoriasis is a chronic inflammatory disorder associated with increased cardiovascular mortality. Psoriasis affects high-density lipoprotein (HDL) composition, generating dysfunctional HDL particles. However, data regarding the impact of anti-psoriatic therapy on HDL composition and function are not available. HDL was isolated from 15 psoriatic patients at baseline and after effective topical and/or systemic anti-psoriatic therapy and from 15 age- and sex-matched healthy controls. HDL from psoriatic patients showed a significantly impaired capability to mobilize cholesterol from macrophages (6.4 vs. 8.0% [(3)H]cholesterol efflux, P<0.001), low paraoxonase (217 vs. 350??M(-1)?minute(-1)?mg(-1) protein, P=0.011) and increased Lp-PLA2 activities (19.9 vs. 12.1?nM(-1)?minute(-1)?mg(-1) protein, P=0.028). Of particular interest, the anti-psoriatic therapy significantly improved serum lecithin-cholesterol acyltransferase activity and decreased total serum lipolytic activity but did not affect serum levels of HDL-cholesterol. Most importantly, these changes were associated with a significantly improved HDL-cholesterol efflux capability. Our results provide evidence that effective anti-psoriatic therapy recovers HDL composition and function, independent of serum HDL-cholesterol levels, and support to the emerging concept that HDL function may be a better marker of cardiovascular risk than HDL-cholesterol levels. PMID:23985995

Holzer, Michael; Wolf, Peter; Inzinger, Martin; Trieb, Markus; Curcic, Sanja; Pasterk, Lisa; Weger, Wolfgang; Heinemann, Akos; Marsche, Gunther



l-Cystathionine Inhibits the Mitochondria-Mediated Macrophage Apoptosis Induced by Oxidized Low Density Lipoprotein  

PubMed Central

This study was designed to investigate the regulatory role of l-cystathionine in human macrophage apoptosis induced by oxidized low density lipoprotein (ox-LDL) and its possible mechanisms. THP-1 cells were induced with phorbol 12-myristate 13-acetate (PMA) and differentiated into macrophages. Macrophages were incubated with ox-LDL after pretreatment with l-cystathionine. Superoxide anion, apoptosis, mitochondrial membrane potential, and mitochondrial permeability transition pore (MPTP) opening were examined. Caspase-9 activities and expression of cleaved caspase-3 were measured. The results showed that compared with control group, ox-LDL treatment significantly promoted superoxide anion generation, release of cytochrome c (cytc) from mitochondrion into cytoplasm, caspase-9 activities, cleavage of caspase-3, and cell apoptosis, in addition to reduced mitochondrial membrane potential as well as increased MPTP opening. However, 0.3 and 1.0 mmol/L l-cystathionine significantly reduced superoxide anion generation, increased mitochondrial membrane potential, and markedly decreased MPTP opening in ox-LDL + l-cystathionine macrophages. Moreover, compared to ox-LDL treated-cells, release of cytc from mitochondrion into cytoplasm, caspase-9 activities, cleavage of caspase-3, and apoptosis levels in l-cystathionine pretreated cells were profoundly attenuated. Taken together, our results suggested that l-cystathionine could antagonize mitochondria-mediated human macrophage apoptosis induced by ox-LDL via inhibition of cytc release and caspase activation. PMID:25514411

Zhu, Mingzhu; Du, Junbao; Chen, Siyao; Liu, Angie Dong; Holmberg, Lukas; Chen, Yonghong; Zhang, Chunyu; Tang, Chaoshu; Jin, Hongfang



Accumulation of 99mTc-low-density lipoprotein in human malignant glioma.  

PubMed Central

Low-density lipoprotein (LDL) uptake in gliomas was studied to find out if LDL has potential as a drug carrier of boron, especially for boron neutron capture therapy. Single photon emission tomography (SPET) was performed 2 h and 20 h after intravenous injection of autologous 99mTc-labelled LDL in four patients with untreated and five patients with recurrent glioma. 99mTc-LDL uptake was compared with the uptake of 99mTc-labelled human serum albumin (HSA), an established blood pool marker. The intra- and peritumoral distributions of radioactivity in the SPET images were not identical for radiolabelled LDL and HSA. The mean LDL tumour to brain ratio, determined from transversal SPET slices at 20 h post injection, was 1.5 in untreated and 2.2 in recurrent gliomas; the corresponding ratios for HSA were 1.6 and 3.4. The brain to blood ratio remained constant at 2 h and 20 h in both types of tumours. These data are not consistent with highly selective, homogeneous uptake of LDL in gliomas. However, the different tumoral distribution and rate of uptake of 99mTc-LDL, as compared with 99mTc-HSA, indicate that the uptake of LDL is different from that of HSA and that further studies on the mechanism of LDL uptake in glioma are warranted. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:7841057

Leppälä, J.; Kallio, M.; Nikula, T.; Nikkinen, P.; Liewendahl, K.; Jääskeläinen, J.; Savolainen, S.; Gylling, H.; Hiltunen, J.; Callaway, J.



Intercorrelations among plasma high density lipoprotein, obesity and triglycerides in a normal population  

SciTech Connect

The interrelationships among fatness measures, plasma triglycerides and high density lipoproteins (HDL) were examined in 131 normal adult subjects: 38 men aged 27 to 46, 50 men aged 47 to 66, 29 women aged 27 to 46 and 24 women aged 47 to 66. None of the women were taking estrogens or oral contraceptive medication. The HDL concentration was subdivided into HDL/sub 2b/, HDL/sub 2a/ and HDL by a computerized fitting of the total schileren pattern to reference schlieren patterns. Anthropometric measures employed included skinfolds at 3 sites, 2 weight/height indices and 2 girth measurements. A high correlation was found among the various fatness measures. These measures were negatively correlated with total HDL, reflecting the negative correlation between fatness measures and HDL/sub 2/ (as the sum of HDL/sub 2a/ and /sub 2b/). Fatness measures showed no relationship to HDL/sub 3/. There was also an inverse correlation between triglyceride concentration and HDL/sub 2/. No particular fatness measure was better than any other for demonstrating the inverse correlation with HDL but multiple correlations using all of the measures of obesity improved the correlations. Partial correlations controlling for fatness did not reduce any of the significnt correlations between triglycerides and HDL/sub 2/ to insignificance. The weak correlation between fatness and triglycerides was reduced to insigifnicance when controlled for HDL/sub 2/.

Albrink, M.J. (West Virgina Unov., Morgantown); Krauss, R.M.; Lindgren, F.T.; von der Groeben, J.; Pan, S.; Wood, P.D.



Revising the high-density lipoprotein targeting strategies - insights from human and preclinical studies.  


In recent years, the high-density lipoprotein (HDL) hypothesis has been challenged. Several completed randomized clinical trials continue to fall short in demonstrating HDL, or at least HDL-cholesterol (HDL-C) levels, as being a consistent target in the prevention of cardiovascular diseases. However, population studies and findings in lipid modifying trials continue to strongly support HDL-C as a superb risk predictor. It is increasingly evident that the complexity of HDL metabolism confounds the use of HDL-C concentration as a unified target. However, important insights continue to emerge from the post hoc analyses of recently completed (i) fibrate-based FIELD and ACCORD trials, including the unexpected beneficial effect of fibrates in microvascular diseases, (ii) the niacin-based AIM-HIGH and HPS2-THRIVE studies, (iii) recombinant HDL-based as well as (iv) the completed CETP inhibitor-based trials. These together with on-going mechanistic studies on novel pathways, which include the unique roles of microRNAs, post-translational remodeling of HDL and novel pathways related to HDL modulators will provide valuable insights to guide how best to refocus and redesign the conceptual framework for selecting HDL-based targets. PMID:25115413

Nesan, Dinushan; Ng, Dominic S



Glucuronic Acid Epimerase Is Associated with Plasma Triglyceride and High Density Lipoprotein Cholesterol Levels in Turks  

PubMed Central

Summary We narrowed chromosome 15q21-23 linkage to plasma high density lipoprotein cholesterol (HDL-C) levels in atherogenic dyslipidemic Turkish families by fine mapping, then focused on glucuronic acid epimerase (GLCE), a heparan sulfate proteoglycan (HSPG) biosynthesis enzyme. HSPGs participate in lipid metabolism along with apolipoprotein (apo) E. Of 31 SNPs in the GLCE locus, nine analyzed by haplotype were associated with plasma HDL-C and triglyceride levels (permuted p = 0.006 and 0.013, respectively) in families. Of five tagging GLCE SNPs in two cohorts of unrelated subjects, three (rs16952868, rs11631403, rs3865014) were associated with triglyceride and HDL-C levels in males (non-permuted p < 0.05). The association was stronger in APOE 2/3 subjects (apoE2 has reduced binding to HSPGs) and reached multiple-testing significance (p < 0.05) in both males and females (n = 2612). Similar results were obtained in the second cohort (n = 1164). Interestingly, at the GLCE locus, bounded by recombination hotspots, Turks had a minor allele frequency of SNPs resembling Chinese more than European ancestry; adjoining regions on chromosome 15 resembled the European pattern. Studies of glce+/–apoe–/– mice fed a chow or high-fat diet supported a role for GLCE in lipid metabolism. Thus, SNPs in GLCE are associated with triglyceride and HDL-C levels in Turks, and mouse studies support a role for glce in lipid metabolism. PMID:21488854

Hodo?lugil, U?ur; Williamson, David W.; Yu, Yi; Farrer, Lindsay A.; Mahley, Robert W.



The role of lectin-like oxidised low-density lipoprotein receptor-1 in vascular pathology.  


The lectin-like oxidised low-density lipoprotein receptor-1 (LOX-1) is a vascular scavenger receptor that plays a central role in the pathogenesis of atherothrombotic disease, which remains the main cause of mortality in the Western population. Recent evidence indicates that targeting LOX-1 represents a credible strategy for the management vascular disease and the current review explores the role of this molecule in the diagnosis and treatment of atherosclerosis. LOX-1-mediated pro-atherogenic effects can be inhibited by anti-LOX-1 monoclonal antibodies and procyanidins, whereas downregulation of LOX-1 expression has been achieved by antisense oligonucleotides and a specific pyrrole-imidazole polyamide. Furthermore, LOX-1 can be utilised for plaque imaging using monoclonal antibodies and even the selective delivery of anti-atherosclerotic agents employing immunoliposome techniques. Also, plasma levels of the circulating soluble form of LOX-1 levels are elevated in atherosclerosis and therefore may constitute an additional diagnostic biomarker of vascular pathology. PMID:25216847

Shaw, Daniel James; Seese, Rachel; Ponnambalam, Sreenivasan; Ajjan, Ramzi



Equilibrium and kinetic studies of the interactions of a porphyrin with low-density lipoproteins.  

PubMed Central

Low-density lipoproteins (LDL) play a key role in the delivery of photosensitizers to tumor cells in photodynamic therapy. The interaction of deuteroporphyrin, an amphiphilic porphyrin, with LDL is examined at equilibrium and the kinetics of association/dissociation are determined by stopped-flow. Changes in apoprotein and porphyrin fluorescence suggest two classes of bound porphyrins. The first class, characterized by tryptophan fluorescence quenching, involves four well-defined sites. The affinity constant per site is 8.75 x 10(7) M(-1) (cumulative affinity 3.5 x 10(8) M(-1)). The second class corresponds to the incorporation of up to 50 molecules into the outer lipidic layer of LDL with an affinity constant of 2 x 10(8) M(-1). Stopped-flow experiments involving direct LDL porphyrin mixing or porphyrin transfer from preloaded LDL to albumin provide kinetic characterization of the two classes. The rate constants for dissociation of the first and second classes are 5.8 and 15 s(-1); the association rate constants are 5 x 10(8) M(-1) s(-1) per site and 3 x 10(9) M(-1) s(-1), respectively. Both fluorescence and kinetic analysis indicate that the first class involves regions at the boundary between lipids and the apoprotein. The kinetics of porphyrin-LDL interactions indicates that changes in the distribution of photosensitizers among various carriers could be very sensitive to the specific tumor microenvironment. PMID:12496113

Bonneau, Stéphanie; Vever-Bizet, Christine; Morlière, Patrice; Mazière, Jean-Claude; Brault, Daniel



Rosiglitazone attenuates atherosclerosis and increases high-density lipoprotein function in atherosclerotic rabbits.  


Rosiglitazone has been found to have anti-atherogenic effects and to increase serum high-density lipoprotein (HDL) cholesterol (HDL-C) levels. However, in vivo studies investigating the regulation of adenosine triphosphate-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI) by rosiglitazone are limited. Moreover, the effects of rosiglitazone on the function and levels of HDL are unclear. In the present study, we investigated the effects of rosiglitazone on HDL function and its mechanisms of action in atherosclerotic rabbits. Our results revealed that rosiglitazone induced a significant increase in serum HDL-C levels, paraoxonase 1 (PON1) activity, [3H]cholesterol efflux rates, and the expression of ABCA1 and SR-BI in hepatocytes and peritoneal macrophages. The expression of ABCA1 was also increased in aortic lesions. Rosiglitazone markedly reduced serum myeloperoxidase (MPO) activity, aortic intima-media thickness (IMT) and the percentage of plaque area in the aorta. It can thus be concluded that in atherosclerotic rabbits, rosigitazone increases the levels of HDL-C and hinders atherosclerosis. Thus, it improves HDL quality and function, as well as the HDL-induced cholesterol efflux, exerting anti-inflammatory and antioxidant effects. PMID:25604880

Li, Chen; Tu, Yan; Liu, Ting-Rong; Guo, Zhi-Gang; Xie, Di; Zhong, Jian-Kai; Fan, Yong-Zhen; Lai, Wen-Yan



Purification and Characterization of a Bovine Acetyl Low Density Lipoprotein Receptor  

NASA Astrophysics Data System (ADS)

The acetyl low density lipoprotein (LDL) receptor is expressed on macrophages and some endothelial cells and mediates macrophage--foam cell formation in culture. A 220-kDa acetyl LDL binding protein was partially purified from bovine liver membranes and was used to make a specific monoclonal antibody. The 220-kDa protein immunoprecipitated by this antibody retained binding activity, and the antibody was used to detect this protein in cells lining bovine liver sinusoids and on the surface of cultured bovine alveolar macrophages. In the human monocytic cell line THP-1, the expression of both acetyl LDL receptor activity and a 220-kDa acetyl LDL binding protein were dramatically induced in parallel after differentiation to a macrophage-like state induced by phorbol ester. The ligand specificity, tissue and cell-type specificity, and coinduction data indicated that this 220-kDa cell-surface binding protein is probably a receptor that mediates acetyl LDL endocytosis. The 220-kDa protein, which was purified 238,000-fold from bovine lung membranes to near homogeneity using monoclonal antibody affinity chromatography, is a trimer of 77-kDa subunits that contain asparagine-linked carbohydrate chains.

Kodama, Tatsuhiko; Reddy, Pranhitha; Kishimoto, Chiharu; Krieger, Monty



Rosiglitazone attenuates atherosclerosis and increases high-density lipoprotein function in atherosclerotic rabbits  

PubMed Central

Rosiglitazone has been found to have anti-atherogenic effects and to increase serum high-density lipoprotein (HDL) cholesterol (HDL-C) levels. However, in vivo studies investigating the regulation of adenosine triphosphate-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI) by rosiglitazone are limited. Moreover, the effects of rosiglitazone on the function and levels of HDL are unclear. In the present study, we investigated the effects of rosiglitazone on HDL function and its mechanisms of action in atherosclerotic rabbits. Our results revealed that rosiglitazone induced a significant increase in serum HDL-C levels, paraoxonase 1 (PON1) activity, [3H]cholesterol efflux rates, and the expression of ABCA1 and SR-BI in hepatocytes and peritoneal macrophages. The expression of ABCA1 was also increased in aortic lesions. Rosiglitazone markedly reduced serum myeloperoxidase (MPO) activity, aortic intima-media thickness (IMT) and the percentage of plaque area in the aorta. It can thus be concluded that in atherosclerotic rabbits, rosigitazone increases the levels of HDL-C and hinders atherosclerosis. Thus, it improves HDL quality and function, as well as the HDL-induced cholesterol efflux, exerting anti-inflammatory and antioxidant effects. PMID:25604880




Evalution of In Vitro Effect of Flavonoids on Human Low-Density Lipoprotein Carbamylation  

PubMed Central

The non-enzymatic carbamylation of low density lipoprotein (LDL) is a naturally occurring chemical modification of apolipoprotein B as a result of condensation between lysine residues and cyanate derived from urea. Carbamylated LDL is poorly recognized by LDL receptors and initiates different processes that can be considered proatherogenic. Thus, LDL carbamylation may contribute to the increased risk of atherosclerosis in patients with kidney failure. The objective of this study was to investigate in vitro effects of flavonoids on LDL carbamylation. LDL was isolated from plasma using ultracentrifuge technique with a single step discontinuous gradient. Then, cyanate was added to LDL and LDL carbamylation level was estimated in absence and presence of flavonoids by a colorimetric method at 530 nm. The results of this study showed that a number of flavonoids including rutin, catechin, morin, myricetin, kaempferol, taxifolin, luteolin, naringin and quercetin decreased LDL carbamylation in a dose dependent manner. Also, it was demonstrated that these nutrients decreased electrophoretic mobility of carbamylated LDL. Based on the results obtained in this study, it is suggested that flavonoids are able to inhibit LDL carbamylation (probably by scavenging cyanate ions) and thus, may have a role in ameliorating atherosclerotic risk of patients with kidney failure. PMID:24363709

Ghaffari, Mohammad Ali; Shanaki, Mehrnoosh



Uptake and Accumulation of Oxidized Low-Density Lipoprotein during Mycobacterium tuberculosis Infection in Guinea Pigs  

PubMed Central

The typical host response to infection of humans and some animals by M. tuberculosis is the accumulation of reactive oxygen species generating inflammatory cells into discrete granulomas, which frequently develop central caseous necrosis. In previous studies we showed that infection of immunologically naïve guinea pigs with M. tuberculosis leads to localized and systemic oxidative stress that results in a significant depletion of serum total antioxidant capacity and the accumulation of malondialdehyde, a bi-product of lipid peroxidation. Here we show that in addition, the generation of excessive reactive oxygen species in vivo resulted in the accumulation of oxidized low density lipoproteins (OxLDL) in pulmonary and extrapulmonary granulomas, serum and lung macrophages collected by bronchoalveolar lavage. Macrophages from immunologically naïve guinea pigs infected with M. tuberculosis also had increased surface expression of the type 1 scavenger receptors CD36 and LOX1, which facilitate the uptake of oxidized host macromolecules including OxLDL. Vaccination of guinea pigs with Bacillus Calmette Guerin (BCG) prior to aerosol challenge reduced the bacterial burden as well as the intracellular accumulation of OxLDL and the expression of macrophage CD36 and LOX1. In vitro loading of guinea pig lung macrophages with OxLDL resulted in enhanced replication of bacilli compared to macrophages loaded with non-oxidized LDL. Overall, this study provides additional evidence of oxidative stress in M. tuberculosis infected guinea pigs and the potential role OxLDL laden macrophages have in supporting intracellular bacilli survival and persistence. PMID:22493658

Palanisamy, Gopinath S.; Kirk, Natalie M.; Ackart, David F.; Obregón-Henao, Andrés; Shanley, Crystal A.; Orme, Ian M.; Basaraba, Randall J.



Sphingomyelin in High-Density Lipoproteins: Structural Role and Biological Function  

PubMed Central

High-density lipoprotein (HDL) levels are an inverse risk factor for cardiovascular diseases, and sphingomyelin (SM) is the second most abundant phospholipid component and the major sphingolipid in HDL. Considering the marked presence of SM, the present review has focused on the current knowledge about this phospholipid by addressing its variable distribution among HDL lipoparticles, how they acquire this phospholipid, and the important role that SM plays in regulating their fluidity and cholesterol efflux from different cells. In addition, plasma enzymes involved in HDL metabolism such as lecithin–cholesterol acyltransferase or phospholipid transfer protein are inhibited by HDL SM content. Likewise, HDL SM levels are influenced by dietary maneuvers (source of protein or fat), drugs (statins or diuretics) and modified in diseases such as diabetes, renal failure or Niemann–Pick disease. Furthermore, increased levels of HDL SM have been shown to be an inverse risk factor for coronary heart disease. The complexity of SM species, described using new lipidomic methodologies, and their distribution in different HDL particles under many experimental conditions are promising avenues for further research in the future. PMID:23571495

Martínez-Beamonte, Roberto; Lou-Bonafonte, Jose M.; Martínez-Gracia, María V.; Osada, Jesús



Low-density lipoprotein activates the small GTPases Rap1 and Ral in human platelets.  

PubMed Central

Physiological concentrations of low-density lipoprotein (LDL) sensitize blood platelets to alpha-thrombin- and collagen-induced secretion, and after prolonged contact trigger secretion independent of other agonists. Here we report that LDL activates the small GTPases Rap1 and Ral but not Ras, as assessed by specific precipitation of the GTP-bound enzymes. In unstirred suspensions, the inhibitor SB203580 blocks Rap1 activation by 60-70%, suggesting activation via p38 mitogen-activated protein kinase and a second, unidentified route. Inhibitors of cyclooxygenase (indomethacin) and the thromboxane A(2) (TxA(2)) receptor (SQ30741) induce complete inhibition, indicating that Rap1 activation is the result of TxA(2) formation. Stirring reveals a second, TxA(2)-independent Rap1 activation, which correlates quantitatively with a slow induction of dense granule secretion. Both pathways are unaffected by inhibitors of ligand binding to integrin alpha(IIb)beta(3). The results suggest that Rap1 and Ral, but not Ras, may take part in signalling routes initiated by LDL that initially enhance the sensitivity of platelets to other agonists and later trigger LDL-dependent secretion. PMID:10861233

Hackeng, C M; Franke, B; Relou, I A; Gorter, G; Bos, J L; van Rijn , H J; Akkerman, J W



High Density Lipoprotein Nanoparticles Deliver RNAi to Endothelial Cells to Inhibit Angiogenesis.  


Systemic delivery of therapeutic nucleic acids to target cells and tissues outside of the liver remains a major challenge. We synthesized a biomimetic high density lipoprotein nanoparticle (HDL NP) for delivery of a cholesteryl modified therapeutic nucleic acid (RNAi) to vascular endothelial cells, a cell type naturally targeted by HDL. HDL NPs adsorb cholesteryl modified oligonucleotides and protect them from nuclease degradation. As proof of principle, we delivered RNAi targeting vascular endothelial growth factor receptor 2 (VEGFR2) to endothelial cells to effectively silence target mRNA and protein expression in vitro. In addition, data show that treatment strongly attenuated in vivo neovascularization measured using a standard angiogenesis assay and in hypervascular tumor allografts where a striking reduction in tumor growth was observed. For effective delivery, HDL NPs required the expression of the cell surface protein scavenger receptor type-B1 (SR-B1). No toxicity of HDL NPs was measured in vitro or after in vivo administration. Thus, by using a biomimetic approach to nucleic acid delivery, data demonstrate that systemically administered RNAi-HDL NPs target SR-B1 expressing endothelial cells to deliver functional anti-angiogenic RNAi as a potential treatment of cancer and other neo-vascular diseases. PMID:25400330

Tripathy, Sushant; Vinokour, Elena; McMahon, Kaylin M; Volpert, Olga V; Thaxton, C Shad



Dimeric nature of apo-low density lipoprotein extracted with Triton X-100.  


Human low density lipoprotein (LDL) was dissolved in 0.3 to 2.0% Triton X-100 at pH 7.5 and apo-LDL (B protein) was extracted from LDL to form B protein-Triton complex. Sedimentation equilibrium study of this complex in a solvent nearly isopycnic to Triton X-100 showed that the molecular weight of the protein in the complex was 570,000. The complex eluted almost at the void volume of a Sepharose 6B column, as would be expected for a complex with a total molecular weight of roughly 900,000, on the assumption that 0.52 g of Triton was bound to 1 g of protein (Helenius, A. and Simons, K. (1972) J. Biol. Chem. 247, 3656-3661). The sedimentation coefficient of the complex gave f/fmin = 2.2, indicating that the complex was either as asymmetric as a fibrinogen molecule or not compact. These results show that B protein exists in its complex with Triton X-100 as an elongated or a loosely expanded dimer based on the molecular weight of monomeric B protein of 270,000. B protein may also exist in LDL as a dimer. PMID:205534

Ikai, A; Hasegawa, M



Antioxidant vitamin levels in plasma and low density lipoprotein of obese girls.  


To investigate the antioxidant status of obese children, we analyzed beta-carotene and alpha-tocopherol levels in plasma and low density lipoprotein (LDL). We also analyzed the fatty acid composition of LDL as a substrate for oxidative stress. The plasma beta-carotene and alpha-tocopherol levels were relatively lower in obese girls than in normal controls. However, the plasma alpha-tocopherol/lipids ratio was significantly lower in obese girls than in normal controls. Both LDL beta-carotene and LDL alpha-tocopherol levels were significantly lower in obese girls than in normal controls, although no obvious differences were observed in plasma levels. In obese girls LDL contained more polyunsaturated fatty acid (PUFA) compared with normal controls. When the peroxidizability index (PI) was calculated to estimate the susceptibility of lipids to oxidative stress, obese girls had significantly higher PI values than normal controls. Both the LDL beta-carotene/PI ratio and the LDL alpha-tocopherol/PI ratio were significantly lower in obese girls than in normal controls. These results indicate the increased susceptibility of LDL to oxidative stress in obese girls which may promote atherosclerosis later in life. PMID:9554835

Kuno, T; Hozumi, M; Morinobu, T; Murata, T; Mingci, Z; Tamai, H



Thermal Stability of Apolipoprotein A-I in High-Density Lipoproteins by Molecular Dynamics  

PubMed Central

Abstract Apolipoprotein (apo) A-I is an unusually flexible protein whose lipid-associated structure is poorly understood. Thermal denaturation, which is used to measure the global helix stability of high-density lipoprotein (HDL)-associated apoA-I, provides no information about local helix stability. Here we report the use of temperature jump molecular dynamics (MD) simulations to scan the per-residue helix stability of apoA-I in phospholipid-rich HDL. When three 20 ns MD simulations were performed at 500 K on each of two particles created by MD simulations at 310 K, bilayers remained intact but expanded by 40%, and total apoA-I helicity decreased from 95% to 72%. Of significance, the conformations of the overlapping N- and C-terminal domains of apoA-I in the particles were unusually mobile, exposing hydrocarbon regions of the phospholipid to solvent; a lack of buried interhelical salt bridges in the terminal domains correlated with increased mobility. Nondenaturing gradient gels show that 40% expansion of the phospholipid surface of 100:2 particles by addition of palmitoyloleoylphosphatidylcholine exceeds the threshold of particle stability. As a unifying hypothesis, we propose that the terminal domains of apoA-I are phospholipid concentration-sensitive molecular triggers for fusion/remodeling of HDL particles. Since HDL remodeling is necessary for cholesterol transport, our model for remodeling has substantial biomedical implications. PMID:19167289

Jones, Martin K.; Catte, Andrea; Patterson, James C.; Gu, Feifei; Chen, Jianguo; Li, Ling; Segrest, Jere P.



Aggregation and fusion of low-density lipoproteins in vivo and in vitro  

PubMed Central

Low-density lipoproteins (LDLs, also known as ‘bad cholesterol’) are the major carriers of circulating cholesterol and the main causative risk factor of atherosclerosis. Plasma LDLs are 20- to 25-nm nanoparticles containing a core of cholesterol esters surrounded by a phospholipid monolayer and a single copy of apolipoprotein B (550 kDa). An early sign of atherosclerosis is the accumulation of LDL-derived lipid droplets in the arterial wall. According to the widely accepted ‘response-to-retention hypothesis’, LDL binding to the extracellular matrix proteoglycans in the arterial intima induces hydrolytic and oxidative modifications that promote LDL aggregation and fusion. This enhances LDL uptake by the arterial macrophages and triggers a cascade of pathogenic responses that culminate in the development of atherosclerotic lesions. Hence, LDL aggregation, fusion, and lipid droplet formation are important early steps in atherogenesis. In vitro, a variety of enzymatic and nonenzymatic modifications of LDL can induce these reactions and thereby provide useful models for their detailed analysis. Here, we summarize current knowledge of the in vivo and in vitro modifications of LDLs leading to their aggregation, fusion, and lipid droplet formation; outline the techniques used to study these reactions; and propose a molecular mechanism that underlies these pro-atherogenic processes. Such knowledge is essential in identifying endogenous and exogenous factors that can promote or prevent LDL aggregation and fusion in vivo and to help establish new potential therapeutic targets to decelerate or even block these pathogenic reactions. PMID:25197325

Gursky, Olga



Modified Low Density Lipoprotein and Lipoprotein-Containing Circulating Immune Complexes as Diagnostic and Prognostic Biomarkers of Atherosclerosis and Type 1 Diabetes Macrovascular Disease  

PubMed Central

In atherosclerosis; blood low-density lipoproteins (LDL) are subjected to multiple enzymatic and non-enzymatic modifications that increase their atherogenicity and induce immunogenicity. Modified LDL are capable of inducing vascular inflammation through activation of innate immunity; thus, contributing to the progression of atherogenesis. The immunogenicity of modified LDL results in induction of self-antibodies specific to a certain type of modified LDL. The antibodies react with modified LDL forming circulating immune complexes. Circulating immune complexes exhibit prominent immunomodulatory properties that influence atherosclerotic inflammation. Compared to freely circulating modified LDL; modified LDL associated with the immune complexes have a more robust atherogenic and proinflammatory potential. Various lipid components of the immune complexes may serve not only as diagnostic but also as essential predictive markers of cardiovascular events in atherosclerosis. Accumulating evidence indicates that LDL-containing immune complexes can also serve as biomarker for macrovascular disease in type 1 diabetes. PMID:25050779

Orekhov, Alexander N.; Bobryshev, Yuri V.; Sobenin, Igor A.; Melnichenko, Alexandra A.; Chistiakov, Dimitry A.



Molecular determinants of plasma cholesteryl ester transfer protein binding to high density lipoproteins.  


The plasma cholesteryl ester transfer protein (CETP) mediates the transfer of neutral lipids between lipoproteins and is associated with high density lipoproteins (HDL). To understand the mechanism of interaction of CETP with HDL, we studied the binding of pure recombinant CETP to 1-palmitoyl-2-oleoylphosphatidylcholine (POPC)/apoA-I discoidal particles. Separating bound from free CETP using native gradient gel electrophoresis, complexes of CETP with 10-nm hydrodynamic diameter discoidal particles migrated with a diameter of 12-16 nm, compared with approximately 7.5 nm for CETP. At lower ratios of CETP to discs, CETP bound to discs without displacement of apoA-I. CETP alone was unable to generate discoidal complexes. Cross-linking and fluorescence resonance energy transfer experiments indicated that CETP bound to discs as monomers. Cross-linking of CETP to apoA-I in discs suggested proximity of apoA-I and CETP. By negative-stain electron microscopy, discoidal complexes containing CETP and CETP monoclonal antibody showed localization of antibody molecules to the disc edge, suggesting that CETP was bound to the disc edge. The binding of CETP to discs of different composition or size was studied. Discs (10-nm Stokes diameter) prepared with either apoA-I or apoA-II had a similar Kd (120 nM). Inclusion of 1 mol % cholesteryl oleate, 5 mol % cholesterol, or 6 mol % phosphatidylinositol increased the binding affinity of CETP 3-10 times (20-30 nM). In comparison, plasma HDL3 had a Kd of approximately 450 nM. For POPC/apoA-I discs, 10-nm discs bound CETP with much higher affinity than smaller 7.8-nm discs (Kd = 1-2 microM). 7.7-nm hydrodynamic diameter POPC/apoA-I spherical particles containing either triolein or cholesteryl oleate in their core bound CETP with higher affinity (Kd = 50-100 nM) than 7.8-nm POPC/apoA-I discs. Thus, CETP appears to bind to the perimeter of discoidal particles, possibly in a process in which flexible segments in apoA-I or apoA-II accommodate CETP at the disc edge. The binding of CETP to HDL is markedly influenced by overall particle size and shape and by lipid composition, and the increased binding affinity for cholesterol- and cholesteryl ester-containing discs suggests a higher affinity of CETP for nascent than mature HDL. PMID:7744792

Bruce, C; Davidson, W S; Kussie, P; Lund-Katz, S; Phillips, M C; Ghosh, R; Tall, A R



In vitro evaluation of dextran sulfate cellulose beads for whole blood infusion low-density lipoprotein-hemoperfusion.  


We describe results from a feasibility study of a newly developed low-density lipoprotein (LDL) adsorbent designed for use in whole-blood infusion LDL-hemoperfusion. The adsorbent has almost the same chemical structure as the Liposorber adsorbent (dextran sulfate cellulose beads) but has a larger particle size. In whole-blood perfusion tests, the adsorbent adsorbed atherogenic LDL cholesterol directly from whole blood but left concentrations of high-density lipoprotein cholesterol largely unchanged. In whole-blood perfusion tests using fresh human donor blood or bovine blood anticoagulated with acid citrate dextrose solution or sodium citrate, the adsorbent showed minimal side effects in terms of blood cell activation, complement activation, and blood cell loss, suggesting that it has excellent blood compatibility. In addition, the adsorbent showed mechanical stability and absence of hemolysis. In conclusion, the new adsorbent showed the appropriate characteristics for an LDL adsorbent column for use in whole-blood infusion LDL-hemoperfusion. PMID:12423531

Kobayashi, Akira; Nakatani, Masaru; Furuyoshi, Shigeo; Tani, Nobutaka



In vitro studies of PBT Nonwoven Fabrics adsorbent for the removal of low density lipoprotein from hyperlipemia plasma  

NASA Astrophysics Data System (ADS)

Polyanion ligands such as acrylic acid (AA) and heparin were grafted on PBT Nonwoven Fabrics (PBTNF) to study their effect on the adsorption of low density lipoprotein (LDL). These modified PBTNFs were characterized by Horizontal Attenuated Total Reflectance Fourier Transform Infrared spectroscopy and X-ray Photoelectron spectroscopy. The blood compatibilities of the modified PBTNFs were examined using in vitro hemolysis rate (HR), platelet adhesion, total protein (TP) and activated partial thromboplastin time. The results showed that direct immobilized heparin could improve PBTNF-PAA's blood compatibility and decrease the adsorption capability of useful high density lipoprotein, but would possess so low bioactivity that could not further improve the absorption of LDL and TC. Since the PBTNF-PAA55-Heparin adsorbent had quite good adsorption selectivity for these proteins, it can be an excellent candidate for depletion of LDL with good blood compatibility.

Cao, Ye; Wang, Hong; Yang, Chao; Zhong, Rui; Lei, Yu; Sun, Kang; Liu, Jiaxin



Association of a single-nucleotide polymorphism in low-density lipoprotein receptor-related protein 5 gene with bone mineral density  

Microsoft Academic Search

Low-density lipoprotein receptor-related protein 5 (LRP5) is an important regulator of osteoblast growth and differentiation, affecting peak bone mass in vertebrates. Here, we analyzed whether the LRP5 gene was involved in the etiology of postmenopausal osteoporosis, using association analysis between bone mineral density (BMD) and an LRP5 gene single-nucleotide polymorphism (SNP). Association of an SNP in the LRP5 gene at

Tomohiko Urano; Masataka Shiraki; Yoichi Ezura; Masayo Fujita; Emiko Sekine; Shinjiro Hoshino; Takayuki Hosoi; Hajime Orimo; Mitsuru Emi; Yasuyoshi Ouchi; Satoshi Inoue



A step towards quantitative lipoprotein density profiling analysis: applied Rayleigh scattering  

E-print Network

this innovative imaging technique of Rayleigh scattering to ultracentrifuge tubes containing separated lipoproteins, particle concentrations at differing diameters can be calculated. This thesis primarily goes through the time consuming task of optimizing...

Nowlin, Michael



Clinical Significance of Serum Oxidized Low-Density Lipoprotein\\/?2Glycoprotein I Complexes in Patients with Chronic Renal Diseases  

Microsoft Academic Search

Background: Peroxidation of low-density lipoprotein (LDL) plays an important role in the development of dyslipidemias associated with the progression of chronic renal disorders. We recently reported [J Lipid Res 2001;42:697, 2002;43:1486, 2003;44:716] that oxidized LDL (oxLDL) interacts with an endogenous plasma protein, ?2-glycoprotein I (?2GPI), via specific ligands. In the present study, the prevalence and clinical significance of oxLDL\\/?2GPI complexes

Junko Kasahara; Kazuko Kobayashi; Yohei Maeshima; Yasushi Yamasaki; Tatsuji Yasuda; Eiji Matsuura; Hirofumi Makino



Autoxidation of human low density lipoprotein: loss of polyunsaturated fatty acids and vitamin E and generation of aldehydes  

Microsoft Academic Search

The alteration of structural and biological properties of human plasma low density lipoprotein (LDL) exposed to ox- idative conditions is in part ascribed to lipid peroxidation. The objective of this investigation was to measure quantitatively several parameters in oxidizing LDL indicative for lipid perox- idation. Exposure of freshly prepared ElYLA-free LDL to an oxygen-saturated buffer led to a complete depletion

Hermann Esterbauer; Gunther Jurgens; Oswald Quehenberger; Ernst Koller


Long-term experience with extracorporeal low-density lipoprotein cholesterol removal by dextran sulfate cellulose adsorption  

Microsoft Academic Search

Patients with familial hypercholesterolemia have a high incidence of coronary heart disease due to diet- and drug-resistant, elevated low-density lipoprotein cholesterol (LDL-C). Five patients with familial hypercholesterolemia and diet- and drug-resistant LDL-C > 230 mg\\/dl were treated by LDL apheresis using dextran sulfate cellulose adsorption (Liposorber System LA-15, Kaneka). Plasma separation was by 0.5-m2 polysulfone hollow fiber filter. Two columns

P. Schulzeck; C. J. Olbricht; K. M. Koch



Regulation of low-density lipoprotein particle size distribution in NIDDM and coronary disease: importance of serum triglycerides  

Microsoft Academic Search

Summary  An increase of low-density lipoprotein triglycerides (LDL-Tg) was found to be an independent coronary artery disease (CAD) risk factor for non-insulin-dependent diabetic (NIDDM) patients in a recent prospective study. We examined the composition and size of LDL particles in 50 NIDDM men with angiographically verified CAD (NIDDM+ CAD+) and in 50 NIDDM men without CAD (NIDDM+ CAD–) as compared to

S. LahdenperÄ; M. SyvÄnne; J. Kahri; M.-R. Taskinen



Daily supplementation with aged garlic extract, but not raw garlic, protects low density lipoprotein against in vitro oxidation  

Microsoft Academic Search

The oxidation of low density lipoprotein (LDL) is believed to be an important process in the development and progression of atherosclerosis. In this study, human subjects were supplemented daily with one of: 6 g raw garlic; 2.4 g aged garlic extract (AGE); or 0.8 g dl-?-tocopherol acetate for 7 days to determine the effect on the susceptibility of LDL particles

John S. Munday; Kerry A. James; Linley M. Fray; Stephen W. Kirkwood; Keith G. Thompson



Pectin Isolated From Prickly Pear (Opuntia sp.) Modifies Low Density Lipoprotein Metabolism in Cholesterol-Fed Guinea Pigs12  

Microsoft Academic Search

The effect of prickly pear soluble fiber on low density lipoprotein (LDL)metabolism was investi gated by feeding male guinea pigs either a nonpurified diet containing 0.25% cholesterol (HC diet) or the HC diet + 1% prickly pear pectin (HC-P diet). Plasma cholesterol levels were significantly decreased by the HC-P diet, with a 33% decrease in LDLlevels (p < 0.02) and



Lipid Accumulation and Foam Cell Formation in Chinese Hamster Ovary Cells Overexpressing Very Low Density Lipoprotein Receptor  

Microsoft Academic Search

The rabbit very low density lipoprotein receptor gene was introduced into LDL receptor-negative Chinese hamster ovary cells (ldl-A7). Incubation of the transfected cells with rabbit ?-VLDL (5 to 8 ?g protein\\/ml), for 6 days, induced foam cell formation. The cells accumulated lipid droplets visualized by oil red-O staining; the cellular cholesteryl ester and triglyceride content increased two- to threefold. [3H]Oleate

J. Suzuki; S. Takahashi; K. Oida; A. Shimada; M. Kohno; T. Tamai; S. Miyabo; T. Yamamoto; T. Nakai



Long-term efficacy of low-density lipoprotein apheresis on coronary heart disease in familial hypercholesterolemia  

Microsoft Academic Search

Familial hypercholesterolemia (FH) is characterized by severe hypercholesterolemia and premature coronary heart disease (CHD). The lower the plasma cholesterol level, the more likely it is that CHD can be prevented or retarded; aggressive cholesterol-lowering therapies may be indicated for FH patients with CHD. This study describes the long-term (6 years) safety and efficacy of intensive cholesterol-lowering therapies with low-density lipoprotein

Hiroshi Mabuchi; Junji Koizumi; Masami Shimizu; Kouji Kajinami; Susumu Miyamoto; Kousei Ueda; Tadayoshi Takegoshi



Members of the Low Density Lipoprotein Receptor Family Mediate Cell Entry of a Minor-Group Common Cold Virus  

Microsoft Academic Search

A protein binding to a minor-group human rhinovirus (HRV2) was purified from HeLa cell culture supernatant. The amino acid sequences of tryptic peptides showed identity with the human low density lipoprotein (LDL) receptor (LDLR). LDL and HRV2 mutually competed for binding sites on human fibroblasts. Cells down-regulated for LDLR expression yielded much less HRV2 upon infection than cells with up-regulated

Franz Hofer; Martin Gruenberger; Heinrich Kowalski; Herwig Machat; Manfred Huettinger; Ernst Kuechler; Dieter Blaas



Ginkgo Biloba Extract (EGb 761) Protects Human Low-Density Lipoproteins against Oxidative Modification Mediated by Copper  

Microsoft Academic Search

The antioxidant effects of Ginkgo biloba extract (EGb 761) on copper-mediated human low density lipoprotein (LDL) oxidative modification were evaluated by several techniques. Human LDL (0.5 mg\\/ml) in phosphate buffered saline, pH 7.4, was incubated with 10 ?M cupric sulfate at 37°C under air for 8 hours and 24 hours in the presence of varying concentrations of EGb 761. Increases

L. J. Yan; M. T. Droylefaix; L. Packer



The Contribution of Intraabdominal Fat to Gender Differences in Hepatic Lipase Activity and Low\\/High Density Lipoprotein Heterogeneity  

Microsoft Academic Search

Hepatic lipase (HL) hydrolyzes triglyceride and phospholipid in low and high density lipoprotein cholesterol (LDL-C and HDL-C, respectively), and elevated HL activity is associated with small, dense atherogenic LDL particles and reduced HDL2-C. Elevated HL activity is associated with increasing age, male gender, high amounts of in- traabdominal fat (IAF), and the HL gene (LIPC) promoter polymor- phism (C nucleotide




[Localization of a 1-anilinonaphthalen-8-sulfonate fluorescent probe on the surface monolayer of low density lipoproteins].  


A decay of fluorescence probe 1-anilino-8-naphtalene sulfonate (ANS) sorbed on low density lipoproteins (LDL) surface obtained from human plasma was described. It was demonstrated that on the LDL surface the ANS probe is allocated among two pools of molecules with the time of fluorescence decay 4-7 ns and 12-16 ns. One may conclude that 75-90% of the probe is connected with lipid LDL matrix. PMID:2765570

Omel'ianenko, V G; Churakov, A K; Martseniuk, O V; Ruuge, E K



Adenovirus-Mediated Transfer of Low Density Lipoprotein Receptor Gene Acutely Accelerates Cholesterol Clearance in Normal Mice  

Microsoft Academic Search

We have explored the use of adenovirus-mediated gene transfer to transiently elicit production of low density lipoprotein (LDL) receptors in mice. A recombinant adenovirus carrying the human LDL receptor cDNA restored LDL receptor function in receptor-deficient cultured cells. Intravenous injection of recombinant virus acutely lowered plasma cholesterol levels and increased the rate of 125I-labeled LDL clearance from the circulation in

Joachim Herz; Robert D. Gerard



Retroendocytosis of high density lipoproteins by the human hepatoma cell line, HepG2  

SciTech Connect

When human HepG2 hepatoma cells were pulsed with 125I-labeled high density lipoproteins (HDL) and chased in fresh medium, up to 65% of the radioactivity released was precipitable with trichloroacetic acid. Cell-internalized 125I-HDL contributed to the release of acid-precipitable material; when cells were treated with trypsin before the chase to remove 125I-HDL bound to the outer cell membrane, 50% of the released material was still acid-precipitable. Characterization of the radioactive material resecreted by trypsinized cells revealed the presence of particles that were similar in size and density to mature HDL and contained intact apolipoproteins (apo) A-I and A-II. The release of internalized label occurred at 37 degrees C but not at 4 degrees C. Monensin, which inhibits endosomal recycling of receptors, decreased the binding of 125I-HDL to cells by 75%, inhibited the release of internalized radioactivity as acid-precipitable material by 80%, and increased the release of acid-soluble material by 90%. In contrast, the lysosomal inhibitor chloroquine increased the association of 125I-HDL to cells by 25%, inhibited the release of precipitable material by 10%, and inhibited the release of acid-soluble radioactivity by 80%. Pre-incubation with cholesterol caused a 50% increase in the specific binding, internalization, and resecretion of HDL label. Cholesterol affected the release of acid-precipitable label much more (+90%) than that of acid-soluble material (+20%). Taken together, these findings suggest that HepG2 cells can bind, internalize, and resecrete HDL by a retroendocytotic process. Furthermore, the results with cholesterol and monensin indicate that a regulated, recycling, receptor-like molecule is involved in the binding and intracellular routing of HDL.

Kambouris, A.M.; Roach, P.D.; Calvert, G.D.; Nestel, P.J. (CSIRO, Division of Human Nutrition, Adelaide (Australia))



Tissue specific regulation of the high density lipoprotein (HDL) receptor, scavenger receptor Class B, Type I (SR-BI) by the scaffold protein PDZK1  

E-print Network

PDZK1 is a four PDZ-domain containing cytoplasmic adaptor protein that binds the Cterminus of the high-density lipoprotein (HDL) receptor SR-BI. Abolishing PDZK1 expression in PDZK1 knockout (KO) mice leads to a ...

Fenske, Sara Anne



Association between change in high density lipoprotein cholesterol and cardiovascular disease morbidity and mortality: systematic review and meta-regression analysis  

Microsoft Academic Search

Objective To investigate the association between treatment induced change in high density lipoprotein cholesterol and total death, coronary heart disease death, and coronary heart disease events (coronary heart disease death and non-fatal myocardial infarction) adjusted for changes in low density lipoprotein cholesterol and drug class in randomised trials of lipid modifying interventions.Design Systematic review and meta-regression analysis of randomised controlled

Matthias Briel; Ignacio Ferreira-Gonzalez; John J You; Paul J Karanicolas; Elie A Akl; Ping Wu; Boris Blechacz; Dirk Bassler; Xinge Wei; Asheer Sharman; Irene Whitt; Suzana Alves da Silva; Zahira Khalid; Alain J Nordmann; Qi Zhou; Stephen D Walter; Noah Vale; Neera Bhatnagar; Christopher O’Regan; Edward J Mills; Heiner C Bucher; Victor M Montori; Gordon H Guyatt



Mapping the Binding Region on the Low Density Lipoprotein Receptor for Blood Coagulation Factor VIII*  

PubMed Central

Low density lipoprotein receptor (LDLR) was shown to mediate clearance of blood coagulation factor VIII (FVIII) from the circulation. To elucidate the mechanism of interaction of LDLR and FVIII, our objective was to identify the region of the receptor necessary for binding FVIII. Using surface plasmon resonance, we found that LDLR exodomain and its cluster of complement-type repeats (CRs) bind FVIII in the same mode. This indicated that the LDLR site for FVIII is located within the LDLR cluster. Similar results were obtained for another ligand of LDLR, ?-2-macroglobulin receptor-associated protein (RAP), a common ligand of receptors from the LDLR family. We further generated a set of recombinant fragments of the LDLR cluster and assessed their structural integrity by binding to RAP and by circular dichroism. A number of fragments overlapping CR.2-5 of the cluster were positive for binding RAP and FVIII. The specificity of these interactions was tested by site-directed mutagenesis of conserved tryptophans within the LDLR fragments. For FVIII, the specificity was also tested using a single-chain variable antibody fragment directed against the FVIII light chain as a competitor. Both cases resulted in decreased binding, thus confirming its specificity. The mutagenic study also showed an importance of the conserved tryptophans in LDLR for both ligands, and the competitive binding results showed an involvement of the light chain of FVIII in its interaction with LDLR. In conclusion, the region of CR.2-5 of LDLR was defined as the binding site for FVIII and RAP. PMID:23754288

Kurasawa, James H.; Shestopal, Svetlana A.; Karnaukhova, Elena; Struble, Evi B.; Lee, Timothy K.; Sarafanov, Andrey G.



Low-density lipoprotein receptor–related protein 5 governs Wnt-mediated osteoarthritic cartilage destruction  

PubMed Central

Introduction Wnt ligands bind to low-density lipoprotein receptor–related protein (LRP) 5 or 6, triggering a cascade of downstream events that include ?-catenin signaling. Here we explored the roles of LRP5 in interleukin 1? (IL-1?)- or Wnt-mediated osteoarthritic (OA) cartilage destruction in mice. Methods The expression levels of LRP5, type II collagen, and catabolic factors were determined in mouse articular chondrocytes, human OA cartilage, and mouse experimental OA cartilage. Experimental OA in wild-type, Lrp5 total knockout (Lrp5-/-) and chondrocyte-specific knockout (Lrp5fl/fl;Col2a1-cre) mice was caused by aging, destabilization of the medial meniscus (DMM), or intra-articular injection of collagenase. The role of LRP5 was confirmed in vitro by small interfering RNA–mediated knockdown of Lrp5 or in Lrp5-/- cells treated with IL-1? or Wnt proteins. Results IL-1? treatment increased the expression of LRP5 (but not LRP6) via JNK and NF-?B signaling. LRP5 was upregulated in human and mouse OA cartilage, and Lrp5 deficiency in mice inhibited cartilage destruction. Treatment with IL-1? or Wnt decreased the level of Col2a1 and increased those of Mmp3 or Mmp13, whereas Lrp5 knockdown ameliorated these effects. In addition, we found that the functions of LRP5 in arthritic cartilage were subject to transcriptional activation by ?-catenin. Moreover, Lrp5-/- and Lrp5fl/fl;Col2a1-cre mice exhibited decreased cartilage destruction (and related changes in gene expression) in response to experimental OA. Conclusions Our findings indicate that LRP5 (but not LRP6) plays an essential role in Wnt/?-catenin-signaling-mediated OA cartilage destruction in part by regulating the expression levels of type II collagen, MMP3, and MMP13. PMID:24479426



Time course-changes in phosphatidylcholine profile during oxidative modification of low-density lipoprotein  

PubMed Central

Background Oxidized phosphatidylcholines (oxPC) and lysophosphatidylcholine (lysoPC) generated during the formation of oxidized low-density lipoprotein (oxLDL) are involved in atherosclerotic lesion development. We investigated the time course-changes in phosphatidylcholine (PC) molecular species during oxidation of LDL to determine how those atherogenic PCs are produced. Methods Human and rabbit LDLs were pretreated with or without a selective platelet-activating factor acetylhydrolase (PAF-AH) inhibitor. LDL was oxidized by incubation with copper sulfate, and PC profiles were analyzed by liquid chromatography-tandem mass spectrometry. Results When human LDL was oxidized, the peak areas for polyunsaturated fatty acid (PUFA)-containing PC species dramatically decreased after a short lag period, concomitantly lysoPC species increased sharply. Although a variety of oxPC species containing oxidized fatty acyl groups or cleaved acyl chains are formed during LDL oxidation, only a few oxPC products accumulated in oxLDL: 1-palmitoyl-2-(9-oxo-nonanoyl) PC and long-chain oxPC with two double bonds. Pretreatment of LDL with the PAF-AH inhibitor greatly reduced lysoPC production while it had no effect on lipid peroxidation reactions and oxPC profiles. Rabbit LDL, which has a different composition of PC molecular species and needs a longer time to reach achieve full oxidation than human LDL, also accumulated lysoPC during oxidation. The increase in lysoPC in rabbit oxLDL was suppressed by pretreatment with the PAF-AH inhibitor. The major oxPC species formed in rabbit oxLDL were almost the same as human oxLDL. Conclusions These results suggest that lysoPC species are the major products and PAF-AH activity is crucial for lysoPC generation during oxidation of LDL. The oxPC species accumulated are limited when LDL is oxidized with copper ion in vitro. PMID:24625108



Apolipoprotein A1 genotype affects the change in high density lipoprotein cholesterol subfractions with exercise training.  


High density lipoprotein cholesterol (HDL-C) is a primary risk factor for cardiovascular disease. Apolipoprotein A-1 (apoA1) is the major HDL-associated apolipoprotein. The -75G/A single nucleotide polymorphism (SNP) in the apolipoprotein A1 gene (APOA1) promoter has been reported to be associated with HDL-C concentrations as well as HDL-C response to dietary changes in polyunsaturated fat intake. We examined the effect of this APOA1 SNP on exercise-induced changes in HDL subfraction distribution. From a cohort of healthy normolipidemic adults who volunteered for 6 months of supervised aerobic exercise, 75 subjects were genotyped for the -75G/A SNP. Of these, 53 subjects were G homozygotes (G/G) and 22 were A carriers (A/G and A/A). HDL subfractions were measured by nuclear magnetic resonance (NMR) spectroscopy by adding categories HDL-C 1+2 for the small subfraction, and HDL-C 3+4+5 for the large. The change in total HDL-C after exercise was 0.8+/-7.2 mg/dL (+1.7%), and was not statistically significant. HDL subfraction amounts also did not significantly change with exercise training in the total cohort or in G homozygotes or A carriers. The amount of the large HDL subfraction increased in the G homozygotes and decreased in the A carriers (mean+/-S.E.M., 1.8+/-6.6 mg/dL versus -6.1+/-2.3 mg/dL, p<0.0005). In contrast, the amount of the small HDL subfraction decreased in G homozygotes and increased in A carriers (-1.3+/-6.6 mg/dL versus 4.7+/-1.2 mg/dL, p<0.005). These results show that genetic variation at the APOA1 gene promoter is associated with HDL subfraction redistribution resulting from exercise training. PMID:16005460

Ruaño, Gualberto; Seip, Richard L; Windemuth, Andreas; Zöllner, Stefan; Tsongalis, Gregory J; Ordovas, Jose; Otvos, James; Bilbie, Cherie; Miles, Mary; Zoeller, Robert; Visich, Paul; Gordon, Paul; Angelopoulos, Theodore J; Pescatello, Linda; Moyna, Niall; Thompson, Paul D



Pine bark extract prevents low-density lipoprotein oxidation and regulates monocytic expression of antioxidant enzymes.  


Polyphenols are widely distributed in leaves, seeds, bark, and flowers and considered to have beneficial effects on cardiovascular health. We hypothesized that the potent antioxidant properties of pine bark extract (PBE) are exerted by its ability to scavenge free radicals and induce antioxidant enzymes. Therefore, we investigated the effects of PBE on low-density lipoprotein (LDL) oxidation and the antioxidant defense system in monocytes. Oxidative susceptibility of LDL was determined by lag time assay in vitro and by using a human umbilical vein endothelial cell-mediated oxidation model. THP-1 monocytic cells were treated with PBE, and the expression of antioxidant enzymes was measured by real-time polymerase chain reaction and Western blot. Pine bark extract showed radical scavenging ability and significantly inhibited free radical-induced and endothelial cell-mediated LDL oxidation in vitro. Pine bark extract treatment resulted in increases in the expressions of antioxidant enzymes, glutathione peroxidase-1, catalase, and heme oxygenase-1 in THP-1 cells. In addition, PBE induced nuclear factor-erythroid-2-related factor 2 activation, which was accompanied by the activation of extracellular signal-regulated kinase and Akt despite a down-regulation of reactive oxygen species. After the monocyte investigations, we further examined the antioxidant effect after the intake of PBE by 10 healthy male volunteers. Pine bark extract significantly prolonged the lag time of LDL oxidation. Based on our findings, it appears that PBE enhances the antioxidant defense capacity of LDL and monocytes and may play a preventive role in atherosclerosis progression. PMID:25458248

Nakayama, Shiori; Kishimoto, Yoshimi; Saita, Emi; Sugihara, Norie; Toyozaki, Miku; Taguchi, Chie; Tani, Mariko; Kamiya, Tomoyasu; Kondo, Kazuo



Low-density lipoprotein receptor-related protein-1: role in the regulation of vascular integrity.  


Low-density lipoprotein receptor-related protein-1 (LRP1) is a large endocytic and signaling receptor that is widely expressed. In the liver, LRP1 plays an important role in regulating the plasma levels of blood coagulation factor VIII (fVIII) by mediating its uptake and subsequent degradation. fVIII is a key plasma protein that is deficient in hemophilia A and circulates in complex with von Willebrand factor. Because von Willebrand factor blocks binding of fVIII to LRP1, questions remain on the molecular mechanisms by which LRP1 removes fVIII from the circulation. LRP1 also regulates cell surface levels of tissue factor, a component of the extrinsic blood coagulation pathway. This occurs when tissue factor pathway inhibitor bridges the fVII/tissue factor complex to LRP1, resulting in rapid LRP1-mediated internalization and downregulation of coagulant activity. In the vasculature LRP1 also plays protective role from the development of aneurysms. Mice in which the lrp1 gene is selectively deleted in vascular smooth muscle cells develop a phenotype similar to the progression of aneurysm formation in human patient, revealing that these mice are ideal for investigating molecular mechanisms associated with aneurysm formation. Studies suggest that LRP1 protects against elastin fiber fragmentation by reducing excess protease activity in the vessel wall. These proteases include high-temperature requirement factor A1, matrix metalloproteinase 2, matrix metalloproteinase-9, and membrane associated type 1-matrix metalloproteinase. In addition, LRP1 regulates matrix deposition, in part, by modulating levels of connective tissue growth factor. Defining pathways modulated by LRP1 that lead to aneurysm formation and defining its role in thrombosis may allow for more effective intervention in patients. PMID:24504736

Strickland, Dudley K; Au, Dianaly T; Cunfer, Patricia; Muratoglu, Selen C



Conversion of low density lipoprotein-associated phosphatidylcholine to triacylglycerol by primary hepatocytes.  


We have studied the uptake and metabolism of phosphatidylcholine (PC), the major phospholipid of low density lipoproteins (LDL), by cultures of primary hepatocytes. Strikingly, in the absence of the LDL receptor, PC incorporation into hepatocytes was inhibited by only 30%, whereas cholesteryl ether uptake was inhibited by 60-70%. On the other hand, scavenger receptor class B, type I, the other important receptor for LDL in the liver, was found to be responsible for the uptake of the remaining 30-40% of LDL-cholesteryl ether. PC uptake was, however, only partially inhibited (30%) in scavenger receptor class B, type I, knock-out hepatocytes. Once LDL-PC was taken up by hepatocytes, approximately 50% of LDL-[(3)H]oleate-PC was converted to triacylglycerol rather than degraded in lysosomes as occurs for LDL-derived cholesteryl esters. The remainder of the LDL-derived PC was not significantly metabolized to other products. Triacylglycerol synthesis from LDL-PC requires a PC-phospholipase C activity as demonstrated by inhibition with the phospholipase C inhibitor D609 or activation with rattlesnake venom. Small interfering RNA-mediated suppression of acyl-CoA:diacylglycerol acyltransferase 2 (DGAT2), but not DGAT1, decreased the acylation of the LDL-derived diacylglycerol. These findings show that PC in LDL particles is taken up not only by the classical receptors but also by additional mechanism(s) followed by metabolism that is completely different from the cholesteryl esters or apoB100, the other main components of LDL. PMID:18175806

Minahk, Carlos; Kim, Kyung-Wook; Nelson, Randy; Trigatti, Bernardo; Lehner, Richard; Vance, Dennis E



Low-Density-Lipoprotein Particle Size Predicts a Poor Outcome in Patients with Atherothrombotic Stroke  

PubMed Central

Background and Purpose Low-density lipoprotein (LDL) particle size is considered to be one of the more important cardiovascular risk factors, and small LDL particles are known to have atherogenic potential. The aim of this study was to determine whether LDL particle size is associated with stroke severity and functional outcome in patients with atherothrombotic stroke. Methods Between January 2009 and May 2011, 248 patients with first-episode cerebral infarction who were admitted to our hospital within 7 days after symptom onset were prospectively enrolled. LDL particle size was measured using the nondenaturing polyacrylamide gradient gel electrophoresis assay. Stroke severity was assessed by applying the National Institutes of Health Stroke Scale (NIHSS) at admission. Functional outcome was investigated at 3 months after the index stroke using the modified Rankin Scale (mRS), and poor functional outcome was defined as an mRS score of ?3. Results The LDL particle size in the 248 patients was 25.9±0.9 nm (mean±SD). LDL particle size was inversely correlated with the degree of cerebral artery stenosis (p=0.010). Multinomial multivariate logistic analysis revealed that after adjustment for age, sex, and variables with p<0.1 in univariate analysis, LDL particle size was independently and inversely associated with stroke severity (NIHSS score ?5; reference, NIHSS score 0-2; odds ratio=0.38, p=0.028) and poor functional outcome (odds ratio=0.44, p=0.038). Conclusions The results of this study demonstrate that small LDL particles are independently correlated with stroke outcomes. LDL particle size is thus a potential biomarker for the prognosis of atherothrombotic stroke.

Song, Tae-Jin; Cho, Hyun-Ji; Chang, Yoonkyung; Youn, Minjung; Shin, Min-Jeong; Jo, Inho; Heo, Ji Hoe



High density lipoprotein from patients with valvular heart disease uncouples endothelial nitric oxide synthase.  


Normal high density lipoprotein (HDL) protects vascular function; however these protective effects of HDL may absent in valvular heart disease (VHD). Because vascular function plays an important role in maintaining the circulation post-cardiac surgery and some patients are difficult to stabilize, we hypothesized that a deleterious vascular effect of HDL may contribute to vascular dysfunction in VHD patients following surgery. HDL was isolated from age-match 28 healthy subjects and 84 patients with VHD and during cardiac surgery. HDL pro-inflammation index was measured and the effects of HDL on vasodilation, protein interaction, generation of nitric oxide (NO) and superoxide were determined. Patients with VHD received either simvastatin (20mg/d) or routine medications, and endothelial effects of HDL were characterized. HDL inflammation index significantly increased in VHD patients and post-cardiac surgery. HDL from VHD patients and post-cardiac surgery significantly impaired endothelium-dependent vasodilation, inhibited both Akt and endothelial nitric oxide synthase (eNOS) phosphorylation at S1177, eNOS associated with heat shock protein 90 (HSP90), NO production and increased eNOS phosphorylation at T495 and superoxide generation. Simvastatin therapy partially reduced HDL inflammation index, improved the capacity of HDL to stimulate eNOS and Akt phosphorylation at S1177, eNOS associated with HSP90, NO production, reduced eNOS phosphorylation at T495 and superoxide generation, and improved endothelium-dependent vasodilation. Our data demonstrated that HDL from VHD patients and cardiac surgery contributed to endothelial dysfunction through uncoupling of eNOS. This deleterious effect can be reversed by simvastatin, which improves the vasoprotective effects of HDL. Targeting HDL may be a therapeutic strategy for maintaining vascular function and improving the outcomes post-cardiac surgery. PMID:24887036

Chang, Feng-Jun; Yuan, Hai-Yun; Hu, Xiao-Xia; Ou, Zhi-Jun; Fu, Li; Lin, Ze-Bang; Wang, Zhi-Ping; Wang, Shen-Ming; Zhou, Li; Xu, Ying-Qi; Wang, Cui-Ping; Xu, Zhe; Zhang, Xi; Zhang, Chun-Xiang; Ou, Jing-Song



Accurate Quantification of High Density Lipoprotein Particle Concentration by Calibrated Ion Mobility Analysis  

PubMed Central

Background It is critical to develop new metrics to determine whether high density lipoprotein (HDL) is cardioprotective in humans. One promising approach is HDL particle concentration (HDL-P) – the size and concentration of HDL in plasma or serum. However, the two methods currently used to determine HDL-P yield concentrations that differ more than 5-fold. We therefore developed and validated an improved approach to quantify HDL-P, termed calibrated ion mobility analysis (calibrated IMA). Methods HDL was isolated from plasma by ultracentrifugation, introduced into the gas phase with electrospray ionization, separated by size, and quantified by particle counting. A calibration curve constructed with purified proteins was used to correct for the ionization efficiency of HDL particles. Results The concentrations of gold nanoparticles and reconstituted HDLs measured by calibrated IMA were indistinguishable from concentrations determined by orthogonal methods. In plasma of control (n=40) and cerebrovascular disease (n=40) subjects, three subspecies of HDL were reproducibility measured, with an estimated total HDL-P of 13.4±2.4 µM (mean±SD). HDL-C accounted for 48% of the variance in HDL-P. HDL-P was significantly lower in subjects with cerebrovascular disease, and this difference remained significant after adjustment for HDL cholesterol levels. Conclusions Calibrated IMA accurately and reproducibly determined the concentration of gold nanoparticles and synthetic HDL, strongly suggesting the method could accurately quantify HDL particle concentration. Importantly, the estimated stoichiometry of apoA-I determined by calibrated IMA was 3–4 per HDL particle, in excellent agreement with current structural models. Furthermore, HDL-P associated with cardiovascular disease status in a clinical population independently of HDL cholesterol. PMID:25225166

Hutchins, Patrick M.; Ronsein, Graziella E.; Monette, Jeffrey S.; Pamir, Nathalie; Wimberger, Jake; He, Yi; Anantharamaiah, G.M.; Kim, Daniel Seung; Ranchalis, Jane E.; Jarvik, Gail P.; Vaisar, Tomas; Heinecke, Jay W.



High Density Lipoprotein Structure–Function and Role in Reverse Cholesterol Transport  

PubMed Central

High density lipoprotein (HDL) possesses important anti-atherogenic properties and this review addresses the molecular mechanisms underlying these functions. The structures and cholesterol transport abilities of HDL particles are determined by the properties of their exchangeable apolipoprotein (apo) components. ApoA-I and apoE, which are the best characterized in structural terms, contain a series of amphipathic ?-helical repeats. The helices located in the amino-terminal two-thirds of the molecule adopt a helix bundle structure while the carboxy-terminal segment forms a separately folded, relatively disorganized, domain. The latter domain initiates lipid binding and this interaction induces changes in conformation; the ?-helix content increases and the amino-terminal helix bundle can open subsequently. These conformational changes alter the abilities of apoA-I and apoE to function as ligands for their receptors. The apoA-I and apoE molecules possess detergent-like properties and they can solubilize vesicular phospholipid to create discoidal HDL particles with hydrodynamic diameters of ~10 nm. In the case of apoA-I, such a particle is stabilized by two protein molecules arranged in an anti-parallel, double-belt, conformation around the edge of the disc. The abilities of apoA-I and apoE to solubilize phospholipid and stabilize HDL particles enable these proteins to be partners with ABCA1 in mediating efflux of cellular phospholipid and cholesterol, and the biogenesis of HDL particles. ApoA-I-containing nascent HDL particles play a critical role in cholesterol transport in the circulation whereas apoE-containing HDL particles mediate cholesterol transport in the brain. The mechanisms by which HDL particles are remodeled by lipases and lipid transfer proteins, and interact with SR-BI to deliver cholesterol to cells, are reviewed. PMID:20213545

Lund-Katz, Sissel



Association of lipoarabinomannan with high density lipoprotein in blood: implications for diagnostics.  


Understanding the pathophysiology of tuberculosis, and the bio-distribution of pathogen-associated molecules in the host is essential for the development of efficient methods of intervention. One of the key virulence factors in the pathology of tuberculosis infection is Lipoarabinomannan (LAM). Previously, we have demonstrated the reliable detection of LAM in urine from tuberculosis patients in a sandwich immunoassay format. We have also applied an ultra-sensitive detection strategy developed for amphiphilic biomarkers, membrane insertion, to the detection of LAM with a limit of detection of 10 fM. Herein, we evaluate the application of membrane insertion to the detection of LAM in patient serum, and demonstrate that the circulating concentrations of 'monomeric' LAM in serum are very low, despite significantly higher concentrations in the urine. Using spiked samples, we demonstrate that this discrepancy is due to the association of LAM with high-density lipoprotein (HDL) nanodiscs in human serum. Indeed, pull-down of HDL nanodiscs from human serum allows for the recovery of HDL-associated LAM. These studies suggest that LAM is likely associated with carrier molecules such as HDL in the blood of patients infected with tuberculosis. This phenomenon may not be limited to LAM in that many pathogen-associated molecular patterns like LAM are amphiphilic in nature and may also be associated with host lipid carriers. Such interactions are likely to affect host-pathogen interactions, pathogen bio-distribution and clearance in the host, and must be thoroughly understood for the effective design of vaccines and diagnostics. PMID:23507184

Sakamuri, Rama Murthy; Price, Dominique N; Lee, Myungsun; Cho, Sang Nae; Barry, Clifton E; Via, Laura E; Swanson, Basil I; Mukundan, Harshini



Dissection of the Endogenous Cellular Pathways of PCSK9-induced Low Density Lipoprotein Receptor Degradation  

PubMed Central

Elevated levels of plasma low density lipoprotein (LDL)-cholesterol, leading to familial hypercholesterolemia, are enhanced by mutations in at least three major genes, the LDL receptor (LDLR), its ligand apolipoprotein B, and the proprotein convertase PCSK9. Single point mutations in PCSK9 are associated with either hyper- or hypocholesterolemia. Accordingly, PCSK9 is an attractive target for treatment of dyslipidemia. PCSK9 binds the epidermal growth factor domain A (EGF-A) of the LDLR and directs it to endosomes/lysosomes for destruction. Although the mechanism by which PCSK9 regulates LDLR degradation is not fully resolved, it seems to involve both intracellular and extracellular pathways. Here, we show that clathrin light chain small interfering RNAs that block intracellular trafficking from the trans-Golgi network to lysosomes rapidly increased LDLR levels within HepG2 cells in a PCSK9-dependent fashion without affecting the ability of exogenous PCSK9 to enhance LDLR degradation. In contrast, blocking the extracellular LDLR endocytosis/degradation pathway by a 4-, 6-, or 24-h incubation of cells with Dynasore or an EGF-AB peptide or by knockdown of endogenous autosomal recessive hypercholesterolemia did not significantly affect LDLR levels. The present data from HepG2 cells and mouse primary hepatocytes favor a model whereby depending on the dose and/or incubation period, endogenous PCSK9 enhances the degradation of the LDLR both extra- and intracellularly. Therefore, targeting either pathway, or both, would be an effective method to reduce PCSK9 activity in the treatment of hypercholesterolemia and coronary heart disease. PMID:19635789

Poirier, Steve; Mayer, Gaetan; Poupon, Viviane; McPherson, Peter S.; Desjardins, Roxane; Ly, Kevin; Asselin, Marie-Claude; Day, Robert; Duclos, Franck J.; Witmer, Mark; Parker, Rex; Prat, Annik; Seidah, Nabil G.



Simvastatin enhances oxidized?low density lipoprotein?induced macrophage autophagy and attenuates lipid aggregation.  


Macrophage autophagy exerts a protective effect in advanced atherosclerosis. It has previously been reported that oxidized low?density lipoprotein (ox?LDL) induces autophagy in endothelial cells, and simvastatin enhances autophagy in coronary arterial myocytes. However, it is currently unknown whether ox?LDL induces autophagy in macrophages, or whether simvastatin affects macrophage autophagy in atherosclerosis. The present study demonstrated that ox?LDL induced lipid accumulation in the J774A.1 macrophage cell line, in a dose?dependent manner, as determined by oil red O staining. Ox?LDL also induced autophagy in the J774A.1 cells, by converting microtubule?associated protein 1 light chain 3 (LC3) I to LC3 II, which is a well?known autophagy marker. Notably, treatment of the cells with simvastatin elevated ox?LDL?induced macrophage autophagy, this was detected through the conversion of LC3 I to LC3 II and the increased expression of Beclin1, another autophagy marker. Furthermore, it was shown that stimulation with ox?LDL led to the redistribution of green fluorescent protein (GFP)?LC3 from diffusion distribution, to the formation of puncta in the J774A.1 cells. Simvastatin promoted the ox?LDL?induced formation of GFP?LC3 puncta, as detected by confocal laser scanning microscopy. Simvastatin was also shown to inhibit ox?LDL?induced cholesterol accumulation in the J774A.1 cells, as observed by oil red O staining and CHOD?PAP assay. These results suggest that simvastatin may enhance ox?LDL?induced macrophage autophagy and attenuate lipid aggregation. PMID:25351979

Huang, Baojun; Jin, Mengxing; Yan, Hai; Cheng, Yanwei; Huang, Dake; Ying, Songcheng; Zhang, Linjie



Small high-density lipoprotein is associated with monocyte subsets in stable coronary artery disease  

PubMed Central

Objective: High-density lipoprotein (HDL) particles are heterogeneous in structure and function and the role of HDL subfractions in atherogenesis is not well understood. It has been suggested that small HDL may be dysfunctional in patients with coronary artery disease (CAD). Monocytes are considered to play a key role in atherosclerotic diseases. Circulating monocytes can be divided into three subtypes according to their surface expression of CD14 and CD16. Our aim was to examine whether monocyte subsets are associated with HDL subfractions in patients with atherosclerosis. Methods: We included 90 patients with angiographically stable CAD. Monocyte subsets were defined as classical monocytes (CD14++CD16-; CM), intermediate monocytes (CD14++CD16+; IM) and non-classical monocytes (CD14+CD16++; NCM). HDL subfractions were measured by electrophoresis on polyacrylamide gel. Results: Serum levels of small HDL correlated with circulating pro-inflammatory NCM and showed an inverse relationship to circulating CM independently from other lipid parameters, risk factors, inflammatory parameters or statin treatment regime, respectively. IM were not associated with small HDL. In particular, patients with small HDL levels in the highest tertile showed dramatically increased levels of NCM (14.7 ± 7% vs. 10.7 ± 5% and 10.8 ± 5%; p = 0.006) and a decreased proportion of CM (79.3 ± 7% vs. 83.7 ± 6% and 83.9 ± 6%; p = 0.004) compared to patients in the two lower tertiles. In contrast, intermediate HDL, large HDL and total HDL were not associated with monocyte subset distribution. Conclusion: Small HDL levels are associated with pro-inflammatory NCM and inversely correlated with CM. This may suggest that small HDL could have dysfunctional anti-inflammatory properties in patients with established CAD. PMID:25463093

Krychtiuk, Konstantin A.; Kastl, Stefan P.; Pfaffenberger, Stefan; Pongratz, Thomas; Hofbauer, Sebastian L.; Wonnerth, Anna; Katsaros, Katharina M.; Goliasch, Georg; Gaspar, Ludovit; Huber, Kurt; Maurer, Gerald; Dostal, Elisabeth; Oravec, Stanislav; Wojta, Johann; Speidl, Walter S.



Glycomic Analysis of High Density Lipoprotein Shows a Highly Sialylated Particle  

PubMed Central

Many of the functional proteins and lipids in high density lipoprotein (HDL) particles are potentially glycosylated, yet very little is known about the glycoconjugates of HDL. In this study, HDL was isolated from plasma by sequential micro-ultracentrifugation, followed by glycoprotein and glycolipid analysis. N-Glycans, glycopeptides, and gangliosides were extracted and purified followed by analysis with nano-HPLC Chip quadrupole time of flight mass spectrometry and MS/MS. HDL particles were found to be highly sialylated. Most of the N-glycans (?90%) from HDL glycoproteins were sialylated with one or two neuraminic acids (Neu5Ac). The most abundant N-glycan was a biantennary complex type glycan with two sialic acids (Hexose5HexNAc4Neu5Ac2) and was found in multiple glycoproteins using site-specific glycosylation analysis. The observed O-glycans were all sialylated, and most contained a core 1 structure with two Neu5Acs, including those that were associated with apolipoprotein CIII (ApoC-III) and fetuin A. GM3 (monosialoganglioside, NeuAc2–3Gal1–4Glc–Cer) and GD3 (disialoganglioside, NeuAc2–8NeuAc2–3Gal1–4Glc–Cer) were the major gangliosides in HDL. A 60% GM3 and 40% GD3 distribution was observed. Both GM3 and GD3 were composed of heterogeneous ceramide lipid tails, including d18:1/16:0 and d18:1/23:0. This report describes for the first time a glycomic approach for analyzing HDL, highlighting that HDL are highly sialylated particles. PMID:24417605



Automated detection and tracking of individual and clustered cell surface low density lipoprotein receptor molecules.  

PubMed Central

We have developed a technique to detect, recognize, and track each individual low density lipoprotein receptor (LDL-R) molecule and small receptor clusters on the surface of human skin fibroblasts. Molecular recognition and high precision (30 nm) simultaneous automatic tracking of all of the individual receptors in the cell surface population utilize quantitative time-lapse low light level digital video fluorescence microscopy analyzed by purpose-designed algorithms executed on an image processing work station. The LDL-Rs are labeled with the biologically active, fluorescent LDL derivative dil-LDL. Individual LDL-Rs and unresolved small clusters are identified by measuring the fluorescence power radiated by the sub-resolution fluorescent spots in the image; identification of single particles is ascertained by four independent techniques. An automated tracking routine was developed to track simultaneously, and without user intervention, a multitude of fluorescent particles through a sequence of hundreds of time-lapse image frames. The limitations on tracking precision were found to depend on the signal-to-noise ratio of the tracked particle image and mechanical drift of the microscope system. We describe the methods involved in (i) time-lapse acquisition of the low-light level images, (ii) simultaneous automated tracking of the fluorescent diffraction limited punctate images, (iii) localizing particles with high precision and limitations, and (iv) detecting and identifying single and clustered LDL-Rs. These methods are generally applicable and provide a powerful tool to visualize and measure dynamics and interactions of individual integral membrane proteins on living cell surfaces. Images FIGURE 1 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 FIGURE 10 PMID:8061186

Ghosh, R N; Webb, W W



Antioxidant activities of black and yellow soybeans against low density lipoprotein oxidation.  


Several studies have demonstrated that the daily intakes of soy foods were associated with a reduced cardiovascular risk. The aim of our study was to investigate the inhibitory effect of black soybeans on low density lipoprotein (LDL) oxidation in comparison to yellow soybeans. The extract from black soybean had a longer LDL oxidation lag time than that from yellow soybean (205 +/- 16 and 65 +/- 3 min, respectively). When both soybeans were divided into the seed coat and the mixture of the germ and cotyledon, the diluted extract solution from the black soybean seed coat prolonged the lag time significantly more than the original extract of the yellow soybean seed coat. On the other hand, antioxidant effects of the extract from the mixture of germs and cotyledons were similar in both soybeans. Regarding total polyphenol contents, the seed coat of black soybean had a higher polyphenol content than that of yellow soybean (29.0 +/- 0.56 and 0.45 +/- 0.02 mg/g, respectively). Interestingly, the mixture of the germ and cotyledon hydrolyzed by beta-glucosidase in both soybeans showed a stronger inhibitory effect on LDL oxidation than that before being hydrolyzed by beta-glucosidase. These results suggest that black soybeans may be more effective in inhibiting LDL oxidation than yellow soybeans because of total polyphenols contents in its seed coat. In addition, aglycones, which are rich in soybeans fermented or hydrolyzed by beta-glucosidase, may play a crucial role in the prevention of oxidation-related diseases. PMID:15913328

Takahashi, Rie; Ohmori, Reiko; Kiyose, Chikako; Momiyama, Yukihiko; Ohsuzu, Fumitaka; Kondo, Kazuo



Increased susceptibility to amyloid-?-induced neurotoxicity in mice lacking the low-density lipoprotein receptor.  


Familial hypercholesterolemia is caused by inherited genetic abnormalities that directly or indirectly affect the function of the low-density lipoprotein (LDL) receptor. This condition is characterized by defective catabolism of LDL which results in increased plasma cholesterol concentrations and premature coronary artery disease. Nevertheless, there is increasing preclinical and clinical evidence indicating that familial hypercholesterolemia subjects show a particularly high incidence of mild cognitive impairment. Moreover, the LDL receptor (LDLr) has been implicated as the main central nervous system apolipoprotein E receptor that regulates amyloid deposition in distinct mouse models of ?-amyloidosis. In this regard, herein we hypothesized that the lack of LDLr would enhance the susceptibility to amyloid-?-(A?)-induced neurotoxicity in mice. Using the acute intracerebroventricular injection of aggregated A?(1-40) peptide (400 pmol/mouse), a useful approach for the investigation of molecular mechanisms involved in A? toxicity, we observed oxidative stress, neuroinflammation, and neuronal membrane damage within the hippocampus of C57BL/6 wild-type mice, which were associated with spatial reference memory and working memory impairments. In addition, our data show that LDLr knockout (LDLr(-/-)) mice, regardless of A? treatment, displayed memory deficits and increased blood-brain barrier permeability. Nonetheless, LDLr(-/-) mice treated with A?(1-40) peptide presented increased acetylcholinesterase activity, astrogliosis, oxidative imbalance, and cell permeability within the hippocampus in comparison with A?(1-40)-treated C57BL/6 wild-type mice. Overall, the present study shows that the lack of LDLr increases the susceptibility to A?-induced neurotoxicity in mice providing new evidence about the crosslink between familial hypercholesterolemia and cognitive impairment. PMID:24577472

de Oliveira, Jade; Moreira, Eduardo Luiz Gasnhar; dos Santos, Danúbia Bonfanti; Piermartiri, Tetsadê Camboim; Dutra, Rafael Cypriano; Pinton, Simone; Tasca, Carla Inês; Farina, Marcelo; Prediger, Rui Daniel Schröder; de Bem, Andreza Fabro



Significance of low density lipoprotein production in the regulations of plasma cholesterol level in man.  

PubMed Central

To determine whether production or catabolism of low density lipoprotein (LDL) is the major factor controlling LDL concentrations in subjects with plasma cholesterol levels from low-normal to mildly elevated, measurements of apoprotein of LDL (apoLDL) turnover were performed in 16 patients with various plasma cholesterol concentrations. Cholesterol balance studies were done simultaneously in 13 of these patients. Plasma concentrations of apoLDL and LDL-cholesterol were positively correlated with synthetic rates of apoLDL (r = 0.74, P less than 0.001; r = 0.50, P less than 0.05, respectively). No correlation was noted between the fractional catabolic rate for apoLDL and apoLDL levels (or LDL-cholesterol). For further analysis, the patients were divided into three groups with stepwise increases in apoLDL concentrations. When apoLDL levels rose significantly, from 83 +/- 5 SEM to 122 +/- 2 to 149 +/- 5 mg/dl, synthetic rates for apoLDL also increased significantly from 11.6 +/- 12. to 17.0 +/- 0.9 to 23.8 +/- 1.8 mg/d/kg ideal weight. In contrast, the fractional catabolic rate of apoLDL was not different among the three groups (0.32 +/- 0.03 vs. 0.29 +/- 0.02 vs. 0.33 +/- 0.03/d). No relation was noted between synthesis of total body cholesterol (or bile acids) and concentrations, production rates, or removal of apoLDL. Thus, concentrations of apoLDL and LDL-cholesterol in these subjects with plasma cholesterol levels from low-normal to mildly elevated were regulated mainly by synthetic rates of apoLDL and not by LDL catabolism. PMID:7085881

Kesaniemi, Y A; Grundy, S M



[In vitro oxidation of low density lipoproteins in patients after ischemic stroke].  


The aim of this work was the evaluation of low density lipoprotein (LDL) susceptibility to oxidation in the survivors of ischaemic stroke. The investigations were performed in 65 individuals at least three months after the onset of acute symptoms. In 24 patients stroke was caused by alterations in main cerebral arteries, in 19 by considerable narrowing of carotid artery, in 15 by alterations in small cerebral arteries with often accompanying hypertension and/or diabetes (lacunar stroke) and in 7 by embolism of cardiac origin in individuals with cardiac arrhythmia and coronary artery disease. The control group comprised 25 age matched persons without pathological symptoms. Plasma lipids and apolipoprotein B levels were determined as well as two antioxidants: alpha-tocopherol level and superoxide dismutase activity. The evaluation of lipid peroxidation was performed by determining thiobarbituric acid reacting substances (TBARS) and lipid peroxides (LPO) increase after 5 hours oxidation of isolated LDL in vitro in the presence of copper ions. The level of IgG directed against modified LDL was also evaluated. In the patients decreased HDL cholesterol level was observed as well as increased apolipoprotein B. In the group of thrombotic strokes high triglycerides were observed. alpha-tocopherol level was decreased in the group of cerebral strokes. The amounts of oxidation products did not differ between the whole group of patients after stroke and the controls. A significant increase concerned only the group of lacunar strokes. The evaluation of LDL susceptibility to oxidation in patients after stroke by measuring absorption at 234 nm and determining the time period necessary to the onset of intensive LDL oxidation will be the subject of a separate publication. PMID:10979539

Wehr, H; Ryglewicz, D; Rodo, M; Po?niak, M; Swiderska, M; Panczenko, B; Stajniak, A



High-density lipoprotein remains elevated despite reductions in total cholesterol in fasting adult male elephant seals (Mirounga angustirostris).  


We examined changes in lipid profiles of 40 adult northern elephant seal bulls over the 3-month breeding fast and the 1-month molting fast to investigate impacts of fasting on serum total cholesterol (TC), triglycerides (TG) and lipoproteins. Total cholesterol and low-density lipoprotein (LDL) levels were initially high (3930 ± 190mgL(-1)and 1610 ± 170mgL(-1), respectively) and decreased significantly over the breeding season. Total cholesterol and LDL declined significantly with adipose tissue reserves (p<0.001), and LDL levels as low as 43 mgL(-1) were measured in seals late in the breeding fast. Less dramatic but similar changes in lipid metabolism were observed across the molting fast. High-density lipoproteins (HDL) remained consistently elevated (>1750 mgL(-1)) suggesting that elephant seals defend HDL concentrations, despite significant depletion of TC and LDL across the breeding fast. Triglyceride levels were significantly higher during the molt, consistent with lower rates of lipid oxidation needed to meet metabolic energy demands during this period. The maintenance of HDL during breeding is consistent with its role in delivering cholesterol from adipose tissue for steroidogenesis and spermatogenesis and potentially mitigates oxidative stress associated with fasting. PMID:21596155

Tift, Michael S; Houser, Dorian S; Crocker, Daniel E



Low-density lipoprotein apheresis using the Liposorber dextran sulfate cellulose system for patients with hypercholesterolemia refractory to medical therapy.  


A subset of patients with familial hypercholesterolemia (FH) have an inadequate lipid-lowering response to diet and drug treatment and should be considered for low-density lipoprotein (LDL)-apheresis therapy. This procedure selectively removes apolipoprotein B-containing particles [LDL, very-low-density lipoprotein, lipoprotein(a)] from plasma independent of diet and drug therapy. Methods for performing LDL-apheresis include dextran sulfate cellulose adsorption, immunoadsorption, and heparin-induced extracorporeal precipitation. The Liposorber Study Group evaluated LDL removal using the Liposorber LA-15 LDL-apheresis System in 64 patients with FH who had not responded adequately to diet and maximal drug therapy. Mean acute reductions in LDL cholesterol (LDL-C) were 76% in heterozygous FH (HtFH) patients and 81% in homozygous FH (HoFH) patients. Time-averaged levels of LDL-C were lowered 41% in HtFH and 53% in HoFH patients. Hypotension was the most frequent side effect, occurring in 3% of procedures. The Liposorber LA-15 System has been approved by the Food and Drug Administration and is recommended for 1) patients with functional homozygous FH (LDL-C level > 500 mg/dL; 2) patients with coronary artery disease (CAD) and LDL-C levels > or = 200 mg/dL; 3) patients without CAD, but an LDL-C level > or = 300 mg/dL. PMID:8915816

Gordon, B R; Saal, S D



Treatment of homozygous familial hypercholesterolemia with low density lipoprotein apheresis: a 4 year follow-up study.  


Hypercholesterolemia and elevated lipoprotein (a) (Lp[a]) levels are considered to be risk factors for the development and progression of premature atherosclerosis. The purpose of our report is to describe the effects of low density lipoprotein (LDL) apheresis (Liposorber system, Kanegafuchi Chemical Industrial Company LTD, Osaka, Japan) on serum lipoprotein concentrations and the clinical status in 2 male patients with homozygous familial hypercholesterolemia. Compared with pretreatment values, the posttreatment concentrations of total cholesterol, LDL cholesterol, and Lp(a) were significantly reduced by 50-60% (p < 0.0001). The concentration of high density lipoprotein (HDL) cholesterol was slightly affected. After one treatment session, LDL cholesterol and Lp(a) were decreased on average by 65% and then increased to reach about 70-75% of the pretreatment values before the next session. Prior to the treatment with LDL apheresis, each patient had suffered one myocardial infarction and had had 2 coronary angiographies. After treatment with LDL apheresis, neither cardiac complaints nor myocardial infarction were observed. The xanthomas were much decreased during the treatment or disappeared. We conclude that LDL apheresis can be continued safely and without major technical problems for several years. Apheresis effectively lowers the serum levels of total and LDL cholesterol. Furthermore, it reduces Lp(a), which is not influenced by lipid-lowering drugs. The reduction of LDL cholesterol and Lp(a) may delay the progression of the atherosclerotic process, thereby helping to reduce the risk of new episodes of coronary heart disease and thus extending the life expectancy in these patients. PMID:9129767

Fadul, J E; Vessby, B; Wikström, B; Danielson, B G



Inhibition of the macrophage-induced oxidation of low density lipoprotein by interferon-gamma.  


The regulation of the macrophage-induced oxidation of low density lipoprotein (LDL) by cytokines was investigated. As an initial source of cytokines, medium from an activated type 2 helper T-cell clone was tested. This cell-free supernatant inhibited the subsequent oxidation of LDL by mouse peritoneal macrophages. The inhibition was concentration- and time-dependent as measured by changes in thiobarbituric acid (TBA) reactive substances. In addition, there were decreases in conjugated diene formation as well as the generation of LDL particles with an increased net negative charge that were recognized by the scavenger receptor. The inhibition was not due to a decrease in cell viability or to nonspecific antioxidant activity, as assessed by measuring phagocytic activity and metal ion-induced oxidation of LDL, respectively. Using antibodies that inactivate specific cytokines, the role of select individual cytokines in this inhibition was investigated. Addition of antibodies against interleukin-3 (IL-3), granulocyte/macrophage-colony stimulating factor (GM-CSF), or tumor necrosis factor alpha (TNF alpha) to the media had little or no effect on the ability of the cytokines to affect oxidation by macrophages, whereas anti-interferon-gamma (IFN-gamma) antibodies completely reversed the inhibition induced by the T-cell supernatant. A role for this cytokine was confirmed using recombinant IFN-gamma. A concentration-dependent inhibition was produced with a maximum inhibition to 24% of control cells, whereas smooth muscle cell-dependent LDL oxidation was not affected. To examine the cellular basis for the inhibition, the effect of IFN-gamma on oxidant activities (O2- production, lipoxygenase activity, and thiol production) were measured. IFN-gamma at concentrations that maximally inhibit LDL oxidation stimulated the phorbol myristate acetate (PMA)-induced production of O2- 1.4-times greater than control cells after one hour. Similarly, thiol production was increased 29% by IFN-gamma pretreatment. In contrast, macrophage lipoxygenase was inhibited approximately 21%. Based on these in vitro findings, the potential regulation of macrophage LDL oxidation by IFN-gamma in vivo was also investigated. Macrophages from Toxoplasma gondii-infected mice have been shown previously to be activated in situ by an IFN-gamma-dependent mechanism. These were tested for their ability to oxidize LDL. Macrophages from these mice oxidized LDL to a much lesser extent than cells from age-matched control mice, demonstrating that the ability of macrophages to oxidize lipoprotein may also be susceptible to regulation possibly also by IFN-gamma in vivo. Together these studies demonstrate that the cell-mediated oxidation of LDL can be regulated by cytokines, specifically IFN-gamma. This mode of regulation may play a role in regulating this process in the developing atherosclerotic lesion. PMID:8071611

Fong, L G; Albert, T S; Hom, S E



Analysis by enzyme-linked immunosorbent assay and 2-dimensional electrophoresis of haptoglobin in the high-density lipoprotein fraction in cows.  


Haptoglobin (Hp) is a hemoglobin (Hb)-binding acute-phase protein. Besides its relevance in inflammation, Hp is involved in the regulation of lipid metabolism. In cattle, in addition to the lipoprotein-deficient fraction, Hp is distributed in high-density lipoprotein (HDL) and very high-density lipoprotein (VHDL) fractions. The purpose of this study was to determine Hp concentrations in the lipoprotein fractions using an enzyme-linked immunosorbent assay (ELISA) based on the affinity with Hb, and also to detect structural differences of HDL Hp from that in the lipoprotein-deficient fraction using 2-dimensional electrophoresis. When purified Hp was used as the antigen for the ELISA, the detection limit was 7.4 ng/ml and linearity was obtained from 14.8 to 475 ng/ml. The correlation coefficient between the ELISA and single radial immunodiffusion was 0.884. The ELISA was shown to be applicable to evaluate Hp concentrations in the lipoprotein fractions. Hp concentrations in the lipoprotein fractions were in the range of 0.94 to 8.77 microg of Hp/ml (n = 4), and concentration ratios were 0.2 to 0.3% of whole serum Hp. Of the lipoprotein fractions, Hp was most abundant in HDL, moderate in VHDL and faint in chylomicrons, the very low-density lipoprotein fraction and low-density lipoprotein fraction. By 2-dimensional electrophoresis, alpha- and beta-chains of serum Hp were each separated into 5 spots, and their isoelectric point (pI) values were from 5.05 to 6.28 in the alpha-chain and from 5.92 to 6.95 in the beta-chain. The pI values of HDL Hp were indistinguishable from those of serum Hp. These results indicate that the ELISA based on the affinity with Hb is useful for evaluating Hp concentrations in lipoprotein fractions, and also suggest that HDL Hp is structurally similar to that in the lipoprotein-deficient fraction. PMID:11217066

Kanno, H; Katoh, N



Dietary Squalene Increases High Density Lipoprotein-Cholesterol and Paraoxonase 1 and Decreases Oxidative Stress in Mice  

PubMed Central

Background and Purpose Squalene, the main hydrocarbon in the unsaponifiable fraction of virgin olive oil, is involved in cholesterol synthesis and it has been reported to own antiatherosclerotic and antiesteatosic effects. However, the squalene's role on lipid plasma parameters and the influence of genotype on this effect need to be addressed. Experimental Approaches Three male mouse models (wild-type, Apoa1- and Apoe- deficient) were fed chow semisynthetic diets enriched in squalene to provide a dose of 1 g/kg during 11 weeks. After this period, their plasma parameters and lipoprotein profiles were analyzed. Key Results Squalene administration at a dose of 1 g/kg showed decreased reactive oxygen species in lipoprotein fractions independently of the animal background and caused an specific increase in high density lipoprotein (HDL)-cholesterol levels, accompanied by an increase in phosphatidylcholine and paraoxonase 1 and no changes in apolipoproteins A1 and A4 in wild-type mice. In these mice, the cholesterol increase was due to its esterified form and associated with an increased hepatic expression of Lcat. These effects were not observed in absence of apolipoprotein A1. The increases in HDL- paraoxonase 1 were translated into decreased plasma malondialdehyde levels depending on the presence of Apolipoprotein A1. Conclusions and Implications Dietary squalene promotes changes in HDL- cholesterol and paraoxonase 1 and decreases reactive oxygen species in lipoproteins and plasma malondialdehyde levels, providing new benefits of its intake that might contribute to explain the properties of virgin olive oil, although the phenotype related to apolipoproteins A1 and E may be particularly relevant. PMID:25117703

Gabás-Rivera, Clara; Barranquero, Cristina; Martínez-Beamonte, Roberto; Navarro, María A.; Surra, Joaquín C.; Osada, Jesús



Low-Density Lipoprotein and Intracerebral Hematoma Expansion in Daily Alcohol Users  

PubMed Central

Background Epidemiological studies suggest that the intracerebral hemorrhage (ICH) rate correlates with alcohol consumption. Alcohol leads to elevated blood pressure (BP) and inhibition of platelet aggregation. These factors could promote excessive bleeding. To our knowledge, in the setting of normal liver function tests, there are no studies that have systematically evaluated the relationship between daily alcohol use and hematoma expansion. The aim of this study is to compare the baseline ICH characteristics, frequency of hematoma expansion, and outcomes in patients with ICH who are daily alcohol users with those who are not daily alcohol users. Methods A retrospective chart review was performed on consecutive patients who presented from July 2008 to July 2013 to the Tulane University Hospital in New Orleans, La., USA, with a spontaneous ICH. Ninety-nine patients who met these criteria were admitted. Patients who underwent hematoma evacuation were excluded. Hemorrhage volumes were calculated based on the ABC/2 method. Low-density lipoprotein (LDL) was dichotomized into low (<100 mg/dl) and high (?100 mg/dl) values. Comparisons were made using t tests, ?2 and nonparametric equivalents where appropriate. ICH growth in 24 h and LDL were evaluated using linear regression. Results Of the 226 patients who met inclusion criteria, 20.4% had a history of daily alcohol use. The average age was 61 years (range 19-94), 55.6% of the patients were males, and 67.1% were of African American origin. Daily alcohol use was associated with male gender, lower rate of home antihypertensive, higher presenting BP, and lower platelet counts, but there was no difference in ICH characteristics, ICH growth, or clinical outcome. Daily alcohol use in patients with a low LDL level was associated with supratentorial location and trends for lower baseline Glasgow Coma Scale score, higher ICH score, and follow-up ICH volume, but no significant difference in significant hematoma expansion or clinical outcome except for a trend for higher mortality was found (25 vs. 9.5%, p = 0.1311) compared to patients with high LDL values. Conclusions Our data suggest that neither chronic daily alcohol use nor a low LDL level in combination with daily alcohol use can be used to predict ICH growth. Daily alcohol use was associated with untreated hypertension and higher BP on presentation. A low LDL level in combination with daily alcohol use may be linked with larger and more severe ICH, but we were unable to demonstrate a relationship with hematoma expansion or poor clinical outcome. The role of LDL in vessel fragility and clot stabilization needs to be further explored before concluding that a low LDL level confers risk of bleeding. PMID:24575109

Pletsch, Gayle R.; Boehme, Amelia K.; Albright, Karen C.; Burns, Christopher; Beasley, T. Mark; Martin-Schild, Sheryl



Relationship between oxidized low-density lipoprotein antibodies and obesity in different glycemic situations  

PubMed Central

Background Autoantibodies to oxidized low-density lipoprotein (oxLDL) are a heterogeneous group of antibodies that are controversially discussed to be either pathogenic or protective. Biochemical and anthropometric measurements correlated with increased levels of these antibodies are also controversial, especially in conditions of impaired glucose tolerance and type 2 diabetes mellitus. The present study was conducted to evaluate levels of oxLDL antibodies and their correlation with obesity in different glycemic situations. Methods Two hundred and seventy-four adult males were classified into three subgroups: group 1 (n=125), comprising a control group of nondiabetic subjects; group 2 (n=77), comprising subjects with impaired glucose tolerance; and group 3 (n=72), comprising patients with type 2 diabetes mellitus. Body mass index was calculated, and measurement of oxLDL and oxLDL antibodies was performed. Results Higher mean concentrations of oxLDL were found in the type 2 diabetes mellitus and impaired glucose tolerance groups (143.5±21.9 U/L and 108.7±23.7 U/L, respectively). The mean value for the control group was 73.5±27.5 U/L (P<0.001). Higher mean concentrations of anti-oxLDL antibodies were observed in the type 2 diabetes mellitus and impaired glucose tolerance groups (55.7±17.8 U/L and 40.4±17.6 U/L, respectively). The mean value for the control group was 20.4±10 U/L (P<0.001). Levels of anti-oxLDL antibodies were found to be positively and significantly correlated with body mass index in the control group (r=0.46), impaired glucose tolerance (r=0.51), type 2 diabetes mellitus group (r=0.46), and in the whole study population (r=0.44; P<0.001). Conclusion Anti-oxLDL antibody levels were increased in subjects with type 2 diabetes mellitus and impaired glucose tolerance and were positively correlated with obesity and body mass index. PMID:25368528

Babakr, Abdullatif Taha; Elsheikh, Osman Mohamed; Almarzouki, Abdullah A; Assiri, Adel Mohamed; Abdalla, Badr Eldin Elsonni; Zaki, Hani Yousif; Fatani, Samir H; NourEldin, EssamEldin Mohamed



Mass spectral analyses of the two major apolipoproteins of great ape high density lipoproteins.  


The two major apolipoproteins associated with human and chimpanzee (Pan troglodytes) high density lipoproteins (HDL) are apoA-I and dimeric apoA-II. Although humans are closely related to great apes, apolipoprotein data do not exist for bonobos (Pan paniscus), western lowland gorillas (Gorilla gorilla gorilla) and the Sumatran orangutans (Pongo abelii). In the absence of any data, other great apes simply have been assumed to have dimeric apoA-II while other primates and most other mammals have been shown to have monomeric apoA-II. Using mass spectrometry, we have measured the molecular masses of apoA-I and apoA-II associated with the HDL of these great apes. Each was observed to have dimeric apoA-II. Being phylogenetically related, one would anticipate these apolipoproteins having a high percentage of invariant sequences when compared with human apolipoproteins. However, the orangutan, which diverged from the human lineage between 16 and 21 million years ago, had an apoA-II with the lowest monomeric mass, 8031.3 Da and the highest apoA-I value, 28,311.7 Da, currently reported for various mammals. Interestingly, the gorilla that diverged from the lineage leading to the human–chimpanzee branch after the orangutan had almost identical mass values to those reported for human apoA-I and apoA-II. But chimpanzee and the bonobo that diverged more recently had identical apoA-II mass values that were slightly larger than reported for the human apolipoprotein. The chimpanzee A-I mass values were very close to those of humans; however, the bonobo had values intermediate to the molecular masses of orangutan and the other great apes. With the already existing genomic data for chimpanzee and the recent entries for the orangutan and gorilla, we were able to demonstrate a close agreement between our mass spectral data and the calculated molecular weights determined from the predicted primary sequences of the respective apolipoproteins. Post-translational modification of these apolipoproteins, involving truncation and oxidation of methionine, are also reported. PMID:21298813

Puppione, Donald L; Donna, Lorenza Della; Laganowsky, Arthur D; Bassilian, Sara; Souda, Puneet; Ryder, Oliver A; Whitelegge, Julian P



Oxidation of Low-Density Lipoprotein by Iron at Lysosomal pH: Implications for Atherosclerosis  

PubMed Central

Low-density lipoprotein (LDL) has recently been shown to be oxidized by iron within the lysosomes of macrophages, and this is a novel potential mechanism for LDL oxidation in atherosclerosis. Our aim was to characterize the chemical and physical changes induced in LDL by iron at lysosomal pH and to investigate the effects of iron chelators and ?-tocopherol on this process. LDL was oxidized by iron at pH 4.5 and 37 °C and its oxidation monitored by spectrophotometry and high-performance liquid chromatography. LDL was oxidized effectively by FeSO4 (5–50 ?M) and became highly aggregated at pH 4.5, but not at pH 7.4. The level of cholesteryl esters decreased, and after a pronounced lag, the level of 7-ketocholesterol increased greatly. The total level of hydroperoxides (measured by the triiodide assay) increased up to 24 h and then decreased only slowly. The lipid composition after 12 h at pH 4.5 and 37 °C was similar to that of LDL oxidized by copper at pH 7.4 and 4 °C, i.e., rich in hydroperoxides but low in oxysterols. Previously oxidized LDL aggregated rapidly and spontaneously at pH 4.5, but not at pH 7.4. Ferrous iron was much more effective than ferric iron at oxidizing LDL when added after the oxidation was already underway. The iron chelators diethylenetriaminepentaacetic acid and, to a lesser extent, desferrioxamine inhibited LDL oxidation when added during its initial stages but were unable to prevent aggregation of LDL after it had been partially oxidized. Surprisingly, desferrioxamine increased the rate of LDL modification when added late in the oxidation process. ?-Tocopherol enrichment of LDL initially increased the rate of oxidation of LDL but decreased it later. The presence of oxidized and highly aggregated lipid within lysosomes has the potential to perturb the function of these organelles and to promote atherosclerosis. PMID:22493939



Double belt structure of discoidal high density lipoproteins: molecular basis for size heterogeneity.  


We recently proposed an all-atom model for apolipoprotein (apo) A-I in discoidal high-density lipoprotein in which two monomers form stacked antiparallel helical rings rotationally aligned by interhelical salt-bridges. The model can be derived a priori from the geometry of a planar bilayer disc that constrains the hydrophobic face of a continuous amphipathic alpha helix in lipid-associated apoA-I to a plane inside of an alpha-helical torus. This constrains each apoA-I monomer to a novel conformation, that of a slightly unwound, curved, planar amphipathic alpha 11/3 helix (three turns per 11 residues). Using non-denaturing gradient gel electrophoresis, we show that dimyristoylphosphocholine discs containing two apoA-I form five distinct particles with maximal Stokes diameters of 98 A (R2-1), 106 A (R2-2), 110 A (R2-3), 114 A (R2-4) and 120 A (R2-5). Further, we show that the Stokes diameters of R2-1 and R2-2 are independent of the N-terminal 43 residues (the flexible domain) of apoA-I, while the flexible domain is necessary and sufficient for the formation of the three larger complexes. On the basis of these results, the conformation of apoA-I on the R2-2 disc can be modeled accurately as an amphipathic helical double belt extending the full length of the lipid-associating domain with N and C-terminal ends in direct contact. The smallest of the discs, R2-1, models as the R2-2 conformation with an antiparallel 15-18 residue pairwise segment of helixes hinged off the disc edge. The conformations of full-length apoA-I on the flexible domain-dependent discs (R2-3, R2-4 and R2-5) model as the R2-2 conformation extended on the disc edge by one, two or three of the 11-residue tandem amphipathic helical repeats (termed G1, G2 and G3), respectively, contained within the flexible domain. Although we consider these results to favor the double belt model, the topographically very similar hairpin-belt model cannot be ruled out entirely. PMID:15491614

Li, Ling; Chen, Jianguo; Mishra, Vinod K; Kurtz, Jennifer A; Cao, Dongfeng; Klon, Anthony E; Harvey, Stephen C; Anantharamaiah, G M; Segrest, Jere P



Allele-specific expression of the low density lipoprotein receptor gene  

SciTech Connect

Approximately 60% of familial hypercholesterolemia (FH) in French Canadians is due to a > 10 kb deletion of the promoter region of the gene encoding the low density lipoprotein (LDL) receptor (LDL-R), allowing determination of the influence of a single LDL-R allele on phenotypic expression of FH. Normal allele haplotypes of approximately 250 heterozygotes were determined with 7 RFLPs. In vitro maximal LDL-R activity of blood lymphocytes from a subset of approximately 150 heterozygotes, measured by immunocytofluorometry, was significantly higher (20 to 30%) in subjects with LDL-R normal allele haplotype G (n=11), and O (n=7) compared to the most frequent haplotype F (n=43), while no differences were observed among F, E (n=11), and the 2 other most prevalent haplotypes (n=43). LDL-R mRNA in these lymphocytes was significantly elevated 2.3-, 1.7-, and 1.8- fold, in G, O, and E, respectively, compared to F, while no significant differences were apparent between F and the other two most frequent haplotyes. Large interindividual variability in lymphocyte LDL-R mRNA levels and activity was observed even among subjects with the same LDL-R normal allele haplotype. However, maximally induced lymphocyte LDL-R mRNA levels correlated poorly with levels measured in freshly isolated cells (n=14). Relative to haplotype F (n=47 women (W), 39 men (M)), mean plasma LDL cholesterol levels adjusted for age and apolipoprotein E genotype were 5-10% lower in men and women with haplotypes G (n=16 W, 12 M) and O (n=8 W, 6 M), and 20% lower in 7 W with haplotype E. These results suggest that (1) normal LDL-R allele haplotype G and O may contain sequence variations which confer relatively high gene expression and (2) environmental and genetic influences other than the LDL-R gene contribute substantially to variability in LDL-R expression and plasma LDL cholesterol levels in French Canadian FH heterozygotes.

Minnich, A.; Lussier-Cacan, S.; Roy, M. [Clincial Research Institute of Montreal, Quebec (Canada)



Synthesis and Characterization of Biomimetic High Density Lipoprotein Nanoparticles To Treat Lymphoma  

NASA Astrophysics Data System (ADS)

High density lipoproteins (HDLs), natural nanoparticles that function as vehicles for cholesterol transport, have enhanced uptake by several human cancers. This uptake is mediated, in part, by the high affinity HDL receptor, scavenger receptor B-1 (SR-B1). More specifically, studies show that the rate of cellular proliferation of lymphoma, a cancer of the lymphocytes, is directly proportional to the amount of HDL-cholesterol available. Thus, targeting of HDL-cholesterol uptake by these cells could be an effective therapeutic approach that may have lower toxicity to healthy cells compared to conventional therapies. Biomimetic HDL can be synthesized using a gold nanoparticle template (HDL-AuNPs), which provides control over size, shape, and surface chemistry. Like their natural counterparts, HDL-AuNPs sequester cholesterol. However, since the gold nanoparticle replaces the cholesterol core of natural HDL, HDL-AuNPs inherently deliver less cholesterol. We show that HDL-AuNPs are able to induce dose dependent apoptosis in B cell lymphoma cell lines and reduce tumor volume following systemic administration to mice bearing B cell lymphoma tumors. Furthermore, HDL-AuNPs are neither toxic to healthy human lymphocytes (SR-B1-), nor to hepatocytes and macrophages (SR-B1+), which are cells naturally encountered by HDLs. Manipulation of cholesterol flux and targeting of SR-B1 are responsible for the efficacy of HDL-AuNPs against B cell lymphoma. HDL-AuNPs could be used to treat B cell lymphomas and other diseases that involve pathologic accumulation of cholesterol. Titanium dioxide nanoparticle (TiO2 NP) core HDLs (HDL-TiO 2 NPs) have been synthesized for high resolution cellular localization studies and for future use as a therapeutic and imaging agent. In initial studies, HDL-TiO(2 NPs display maximum uptake in B cell lymphoma cell lines. X-ray fluorescence microscopy studies show interaction between HDL-TiO2 NPs and cells 10 minutes after treatment and internalization after 1 hour. HDL-TiO2 NPs induce apoptosis in B cell lymphoma cell lines. These results suggest that HDL-TiO2 NPs may be used as therapeutics for lymphoma and other cancers by inducing apoptosis through manipulation of cellular cholesterol flux.

Damiano, Marina Giacoma


High-density lipoproteins induce a rapid and transient release of Ca2+ in cultured fibroblasts.  

PubMed Central

Several different cell types showed increased rates of proliferation and cholesterol mobilization in response to treatment with high-density lipoprotein (HDL). This would suggest that one main function of HDL is the activation of signal pathways in cells. In the current study we have used the fluorescent indicator fura-2 to monitor the level of cytosolic Ca2+ ([Ca2+]i) in human skin fibroblasts. Exposure of subconfluent as well as confluent fibroblasts to HDL3 (20-60 micrograms/ml) resulted in a rapid and transient increase in [Ca2+]i. Sequential additions of HDL3 resulted in diminished rises in [Ca2+]i. The transient rise in [Ca2+]i was observed with HDL prepared from plasma either by conventional ultracentrifugation or by precipitation with dextran sulphate. Chelation of the extracellular Ca2+ with EGTA prior to the addition of HDL3 did not prevent the HDL3-induced rise in [Ca2+]i, suggesting that the mobilized Ca2+ was derived mainly from intracellular stores. Covalent modification of the apoproteins of HDL3 with dimethyl suberimidate or tetranitromethane did not inhibit the HDL3-induced rise in [Ca2+]i. This indicates that the binding of HDL3 to cell surface receptors may not be necessary for the mobilization of intracellular Ca2+. Moreover, the Ca(2+)-releasing effect of HDL3 was not inhibited by the presence of albumin (1%, w/v) in the extracellular medium, suggesting that non-esterified fatty acids were not the cause of the increased [Ca2+]i. The exposure of fibroblasts to lysophosphatidic acid, a potent mitogen and Ca(2+)-releasing agent, before addition of HDL3 completely inhibited the HDL3-induced rise in [Ca2+]i. Furthermore, phorbol 12-myristate 13-acetate blocked the HDL3-induced rise in [Ca2+]i. The results of this study imply that exposure of cells to HDL generates an intracellular signal which is induced by a component of the lipid fraction. PMID:1930148

Pörn, M I; Akerman, K E; Slotte, J P



Different responses to oxidized low-density lipoproteins in human polarized macrophages  

PubMed Central

Background Oxidized low-density lipoprotein (oxLDL) uptake by macrophages plays an important role in foam cell formation. It has been suggested the presence of heterogeneous subsets of macrophage, such as M1 and M2, in human atherosclerotic lesions. To evaluate which types of macrophages contribute to atherogenesis, we performed cDNA microarray analysis to determine oxLDL-induced transcriptional alterations of each subset of macrophages. Results Human monocyte-derived macrophages were polarized toward the M1 or M2 subset, followed by treatment with oxLDL. Then gene expression levels during oxLDL treatment in each subset of macrophages were evaluated by cDNA microarray analysis and quantitative real-time RT-PCR. In terms of high-ranking upregulated genes and functional ontologies, the alterations during oxLDL treatment in M2 macrophages were similar to those in nonpolarized macrophages (M0). Molecular network analysis showed that most of the molecules in the oxLDL-induced highest scoring molecular network of M1 macrophages were directly or indirectly related to transforming growth factor (TGF)-?1. Hierarchical cluster analysis revealed commonly upregulated genes in all subset of macrophages, some of which contained antioxidant response elements (ARE) in their promoter regions. A cluster of genes that were specifically upregulated in M1 macrophages included those encoding molecules related to nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-?B) signaling pathway. Quantitative real-time RT-PCR showed that the gene expression of interleukin (IL)-8 after oxLDL treatment in M2 macrophages was markedly lower than those in M0 and M1 cells. HMOX1 gene expression levels were almost the same in all 3 subsets of macrophages even after oxLDL treatment. Conclusions The present study demonstrated transcriptional alterations in polarized macrophages during oxLDL treatment. The data suggested that oxLDL uptake may affect TGF-?1- and NF-?B-mediated functions of M1 macrophages, but not those of M0 or M2 macrophages. It is likely that M1 macrophages characteristically respond to oxLDL. PMID:21199582



Oxidation of low-density lipoprotein by iron at lysosomal pH: implications for atherosclerosis.  


Low-density lipoprotein (LDL) has recently been shown to be oxidized by iron within the lysosomes of macrophages, and this is a novel potential mechanism for LDL oxidation in atherosclerosis. Our aim was to characterize the chemical and physical changes induced in LDL by iron at lysosomal pH and to investigate the effects of iron chelators and ?-tocopherol on this process. LDL was oxidized by iron at pH 4.5 and 37 °C and its oxidation monitored by spectrophotometry and high-performance liquid chromatography. LDL was oxidized effectively by FeSO(4) (5-50 ?M) and became highly aggregated at pH 4.5, but not at pH 7.4. The level of cholesteryl esters decreased, and after a pronounced lag, the level of 7-ketocholesterol increased greatly. The total level of hydroperoxides (measured by the triiodide assay) increased up to 24 h and then decreased only slowly. The lipid composition after 12 h at pH 4.5 and 37 °C was similar to that of LDL oxidized by copper at pH 7.4 and 4 °C, i.e., rich in hydroperoxides but low in oxysterols. Previously oxidized LDL aggregated rapidly and spontaneously at pH 4.5, but not at pH 7.4. Ferrous iron was much more effective than ferric iron at oxidizing LDL when added after the oxidation was already underway. The iron chelators diethylenetriaminepentaacetic acid and, to a lesser extent, desferrioxamine inhibited LDL oxidation when added during its initial stages but were unable to prevent aggregation of LDL after it had been partially oxidized. Surprisingly, desferrioxamine increased the rate of LDL modification when added late in the oxidation process. ?-Tocopherol enrichment of LDL initially increased the rate of oxidation of LDL but decreased it later. The presence of oxidized and highly aggregated lipid within lysosomes has the potential to perturb the function of these organelles and to promote atherosclerosis. PMID:22493939

Satchell, Leanne; Leake, David S



The relationship of apolipoprotein B and very low density lipoprotein triglyceride with hyperuricemia and gout.  


IntroductionGout results from an innate immune response to monosodium urate (MSU) crystals deposited in joints. Increased very low-density lipoprotein (VLDL) has been associated with gout. The apolipoprotein B (apo B), which is present on VLDL, regulates neutrophil response to MSU crystals and has been positively associated with gout. Furthermore, the gene (A1CF) encoding the complementation factor for the APOB mRNA-editing enzyme is associated with urate levels. However, the relationship of apo B and VLDL with gout and hyperuricemia (HU) is still unclear. Therefore, we tested the association of VLDL and apo B with HU and with gout compared to HU.MethodsNew Zealand European (n =90) and M¿ori and Pacific Island (Polynesian) (n =90) male gout case and control sample sets were divided into normouricemia (NU), asymptomatic HU and gout groups. Size exclusion chromatography and enzyme-linked immunosorbant assay was used to measure VLDL and apo B. Multivariate logistic regression was used to assess the risk of gout and HU per unit change in VLDL and apo B.ResultsIncreased levels of VLDL triglycerides (Tg) were observed in the gout sample set compared to NU and HU in European (P =1.8¿×¿10¿6 and 1¿×¿10¿3, respectively), but only compared to NU in Polynesian (P =0.023). This increase was driven by increased number of VLDL particles in the European participants and by the Tg-enrichment of existing VLDL particles in the Polynesian participants. Each mmol/L increase in VLDL Tg was significantly associated with gout in the presence of HU in Europeans, with a similar trend in Polynesians (OR =7.61, P =0.011 and 2.84, P =0.069, respectively). Each ¿mol/L increase in total apo B trended towards decreased risk of HU (OR =0.47; P =0.062) and, conversely, with increased risk of gout compared to HU (OR =5.60; P =0.004).ConclusionsIncreased VLDL Tg is associated with the risk of gout compared to HU. A genetic approach should be taken to investigate the possibility for causality of VLDL in gout. Apolipoprotein B may have pleiotropic effects in determining HU and gout. PMID:25432151

Rasheed, Humaira; Hsu, Angela; Dalbeth, Nicola; Stamp, Lisa K; McCormick, Sally; Merriman, Tony R



Low density lipoprotein receptor-independent hepatic uptake of a synthetic, cholesterol-scavenging lipoprotein: implications for the treatment of receptor-deficient atherosclerosis  

SciTech Connect

The metabolism of infused /sup 111/In-labeled phospholipid liposomes was examined in Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack low density lipoprotein (LDL) receptors, and in normal control rabbits. The half-times (t/sub 1/2/) for clearance of /sup 111/In and excess phospholipid from plasma were 20.8 +/- 0.9 hr and 20.3 +/- 4.6 hr in WHHL and 20.0 +/- 0.8 hr and 19.6 +/- 2.2 hr in the normal rabbits. By 6 hr postinfusion, the plasma concentration of unesterified cholesterol increased by 2.2 +/- 0.23 mmol/liter in WHHL and 2.1 +/- 0.04 mmol/liter in normal rabbits, presumably reflecting mobilization of tissue sores. Disappearance of excess plasma cholesterol was > 90% complete in both groups of rabbits by 70 hr postinfusion. By quantitative ..gamma.. camera imaging, hepatic trapping of /sup 111/In-labeled liposomes over time was indistinguishable between the two groups. At autopsy, the liver was the major organ of clearance. Aortic uptake of /sup 111/In was < 0.02%. Thus, mobilization of cholesterol and hepatic uptake of phospholipid liposomes do not require LDL receptors. Because phospholipid infusions produce rapid substantial regression of atherosclerosis in genetically normal animals, the results suggest that phospholipid liposomes or triglyceride phospholipid emulsions (e.g., Intralipid) might reduce atherosclerosis in WHHL rabbits and in humans with familial hypercholesterolemia.

Williams, K.J.; Vallabhajosula, S.; Rahman, I.U.; Donnelly, T.M.; Parker, T.S.; Weinrauch, M.; Goldsmith, S.J.



New insights into the role of the adenosine triphosphate–binding cassette transporters in high-density lipoprotein metabolism and reverse cholesterol transport  

Microsoft Academic Search

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

H. Bryan Brewer; Silvia Santamarina-Fojo



Lipoprotein Subfractions in Metabolic Syndrome and Obesity: Clinical Significance and Therapeutic Approaches  

PubMed Central

Small, dense low density lipoprotein (sdLDL) represents an emerging cardiovascular risk factor, since these particles can be associated with cardiovascular disease (CVD) independently of established risk factors, including plasma lipids. Obese subjects frequently have atherogenic dyslipidaemia, including elevated sdLDL levels, in addition to elevated triglycerides (TG), very low density lipoprotein (VLDL) and apolipoprotein-B, as well as decreased high density lipoprotein cholesterol (HDL-C) levels. Obesity-related co-morbidities, such as metabolic syndrome (MetS) are also characterized by dyslipidaemia. Therefore, agents that favourably modulate LDL subclasses may be of clinical value in these subjects. Statins are the lipid-lowering drug of choice. Also, anti-obesity and lipid lowering drugs other than statins could be useful in these patients. However, the effects of anti-obesity drugs on CVD risk factors remain unclear. We review the clinical significance of sdLDL in being overweight and obesity, as well as the efficacy of anti-obesity drugs on LDL subfractions in these individuals; a short comment on HDL subclasses is also included. Our literature search was based on PubMed and Scopus listings. Further research is required to fully explore both the significance of sdLDL and the efficacy of anti-obesity drugs on LDL subfractions in being overweight, obesity and MetS. Improving the lipoprotein profile in these patients may represent an efficient approach for reducing cardiovascular risk. PMID:23507795

Nikolic, Dragana; Katsiki, Niki; Montalto, Giuseppe; Isenovic, Esma R.; Mikhailidis, Dimitri P.; Rizzo, Manfredi



Current status of low density lipoprotein-apheresis for the therapy of severe hyperlipidemia.  


The use of LDL-apheresis to treat patients with severe hypercholesterolemia has gained wider clinical acceptance during the past 2-3 years, particularly in patients with coronary artery disease. Systems utilizing immunoadsorption columns, dextran sulfate cellulose columns and heparin precipitation have been most commonly employed. New or improved technologies include whole-blood compatible columns, double-filtration plasmapheresis and lipoprotein (a)-apheresis. The mechanisms for clinical improvement extend beyond simple regression of atherosclerotic plaque. PMID:9117142

Gordon, B R; Saal, S D



Fenofibrate increases high-density lipoprotein and sphingosine 1 phosphate concentrations limiting abdominal aortic aneurysm progression in a mouse model.  


There are currently no acceptable treatments to limit progression of abdominal aortic aneurysm (AAA). Increased serum concentrations of high-density lipoprotein (HDL) are associated with reduced risk of developing an AAA. The present study aimed to assess the effects of fenofibrate on aortic dilatation in a mouse model of AAA. Male low-density lipoprotein receptor-deficient (Ldlr(-/-)) mice were maintained on a high-fat diet for 3 weeks followed by 6 weeks of oral administration of vehicle or fenofibrate. From 14 to 18 weeks of age, all mice were infused with angiotensin II (AngII). At 18 weeks of age, blood and aortas were collected for assessment of serum lipoproteins, aortic pathology, aortic Akt1 and endothelial nitric oxide synthase (eNOS) activities, immune cell infiltration, eNOS and inducible NOS (iNOS) expression, sphingosine 1 phosphate (S1P) receptor status, and apoptosis. Mice receiving fenofibrate had reduced suprarenal aortic diameter, reduced aortic arch Sudan IV staining, higher serum HDL levels, increased serum S1P concentrations, and increased aortic Akt1 and eNOS activities compared with control mice. Macrophages, T lymphocytes, and apoptotic cells were less evident and eNOS, iNOS, and S1P receptors 1 and 3 were up-regulated in aortas from mice receiving fenofibrate. The present findings suggest that fenofibrate antagonizes AngII-induced AAA and atherosclerosis by up-regulating serum HDL and S1P levels, with associated activation of NO-producing enzymes and reduction of aortic inflammation. PMID:22698985

Krishna, Smriti M; Seto, Sai Wang; Moxon, Joseph V; Rush, Catherine; Walker, Philip J; Norman, Paul E; Golledge, Jonathan



Peroxisome proliferator-activated receptor-? regulates the expression and function of very-low-density lipoprotein receptor  

PubMed Central

Very-low-density lipoprotein receptor (VLDLR) is a member of the low-density receptor family, highly expressed in adipose tissue, heart, and skeletal muscle. It binds apolipoprotein E-triglyceride-rich lipoproteins and plays a significant role in triglyceride metabolism. PPAR? is a primary regulator of lipid metabolism in adipocytes and controls the expression of an array of genes involved in lipid trafficking in adipocytes. However, it is not known whether VLDLR is also under the control of PPAR?. In this study, we investigated the role of PPAR? in the regulation of VLDLR expression and function in vivo and in vitro. During the differentiation of 3T3-L1 preadipocytes, the levels of VLDLR protein and mRNA increased in parallel with the induction of PPAR? expression and reached maximum in mature adipocytes. Treatment of differentiated adipocytes with PPAR? agonist pioglitazone upregulated VLDLR expression in dose- and time-dependent manners. In contrast, specific inhibition of PPAR? significantly downregulated the protein level of VLDLR. Induction of VLDLR is also demonstrated in vivo in adipose tissue of wild-type (WT) mice treated with pioglitazone. In addition, pioglitazone increased plasma triglyceride-rich lipoprotein clearance and increased epididymal fat mass in WT mice but failed to induce similar effects in vldlr?/? mice. These results were further corroborated by the finding that pioglitazone treatment enhanced adipogenesis and lipid deposition in preadipocytes of WT mice, while its effect in VLDLR-null preadipocytes was significantly blunted. These findings provide direct evidence that VLDLR expression is regulated by PPAR? and contributes in lipid uptake and adipogenesis. PMID:19861583

Tao, Huan; Aakula, Srikanth; Abumrad, Naji N.



Endothelial NOS-dependent activation of c-Jun NH(2)- terminal kinase by oxidized low-density lipoprotein  

NASA Technical Reports Server (NTRS)

Oxidized low-density lipoprotein (oxLDL) is known to activate a number of signal transduction pathways in endothelial cells. Among these are the c-Jun NH(2)-terminal kinase (JNK), also known as stress-activated protein kinase, and extracellular signal-regulated kinase (ERK). These mitogen-activated protein kinases (MAP kinase) determine cell survival in response to environmental stress. Interestingly, JNK signaling involves redox-sensitive mechanisms and is activated by reactive oxygen and nitrogen species derived from both NADPH oxidases, nitric oxide synthases (NOS), peroxides, and oxidized low-density lipoprotein (oxLDL). The role of endothelial NOS (eNOS) in the activation of JNK in response to oxLDL has not been examined. Herein, we show that on exposure of endothelial cells to oxLDL, both ERK and JNK are activated through independent signal transduction pathways. A key role of eNOS activation through a phosphatidylinositol-3-kinase-dependent mechanism leading to phosphorylation of eNOS is demonstrated for oxLDL-dependent activation of JNK. Moreover, we show that activation of ERK by oxLDL is critical in protection against the cytotoxicity of oxLDL.

Go, Y. M.; Levonen, A. L.; Moellering, D.; Ramachandran, A.; Patel, R. P.; Jo, H.; Darley-Usmar, V. M.



Myeloid-Specific I?B Kinase ? Deficiency Decreases Atherosclerosis in Low-Density Lipoprotein Receptor–Deficient Mice  

PubMed Central

Objective Inflammatory responses are the driving force of atherosclerosis development. I?B kinase ? (IKK?), a central coordinator in inflammation through regulation of nuclear factor-?B, has been implicated in the pathogenesis of atherosclerosis. Macrophages play an essential role in the initiation and progression of atherosclerosis, yet the role of macrophage IKK? in atherosclerosis remains elusive and controversial. This study aims to investigate the impact of IKK? expression on macrophage functions and to assess the effect of myeloid-specific IKK? deletion on atherosclerosis development. Methods and Results To explore the issue of macrophage IKK? involvement of atherogenesis, we generated myeloid-specific IKK?-deficient low-density lipoprotein receptor–deficient mice (IKK??MyeLDLR?/?). Deficiency of IKK? in myeloid cells did not affect plasma lipid levels but significantly decreased diet-induced atherosclerotic lesion areas in the aortic root, brachiocephalic artery, and aortic arch of low-density lipoprotein receptor–deficient mice. Ablation of myeloid IKK? attenuated macrophage inflammatory responses and decreased atherosclerotic lesional inflammation. Furthermore, deficiency of IKK? decreased adhesion, migration, and lipid uptake in macrophages. Conclusion The present study demonstrates a pivotal role for myeloid IKK? expression in atherosclerosis by modulating macrophage functions involved in atherogenesis. These results suggest that inhibiting nuclear factor-?B activation in macrophages may represent a feasible approach to combat atherosclerosis. PMID:23023371

Park, Se-Hyung; Sui, Yipeng; Gizard, Florence; Xu, Jinxian; Rios-Pilier, Jennifer; Helsley, Robert N.; Han, Seong-Su; Zhou, Changcheng



Antagonism of Secreted PCSK9 Increases Low Density Lipoprotein Receptor Expression in HepG2 Cells  

SciTech Connect

PCSK9 is a secreted protein that degrades low density lipoprotein receptors (LDLRs) in liver by binding to the epidermal growth factor-like repeat A (EGF-A) domain of the LDLR. It is not known whether PCSK9 causes degradation of LDLRs within the secretory pathway or following secretion and reuptake via endocytosis. Here we show that a mutation in the LDLR EGF-A domain associated with familial hypercholesterolemia, H306Y, results in increased sensitivity to exogenous PCSK9-mediated cellular degradation because of enhanced PCSK9 binding affinity. The crystal structure of the PCSK9-EGF-A(H306Y) complex shows that Tyr-306 forms a hydrogen bond with Asp-374 in PCSK9 at neutral pH, which strengthens the interaction with PCSK9. To block secreted PCSK9 activity, LDLR (H306Y) subfragments were added to the medium of HepG2 cells stably overexpressing wild-type PCSK9 or gain-of-function PCSK9 mutants associated with hypercholesterolemia (D374Y or S127R). These subfragments blocked secreted PCSK9 binding to cell surface LDLRs and resulted in the recovery of LDLR levels to those of control cells. We conclude that PCSK9 acts primarily as a secreted factor to cause LDLR degradation. These studies support the concept that pharmacological inhibition of the PCSK9-LDLR interaction extracellularly will increase hepatic LDLR expression and lower plasma low density lipoprotein levels.

McNutt, Markey C.; Kwon, Hyock Joo; Chen, Chiyuan; Chen, Justin R.; Horton, Jay D.; Lagace, Thomas A.; (USMC); (UTSMC)



Deletion in the first cysteine-rich repeat of low density lipoprotein receptor impairs its transport but not lipoprotein binding in fibroblasts from a subject with familial hypercholesterolemia  

SciTech Connect

The ligand-binding domain of the low density lipoprotein (LDL) receptor is composed of seven cysteine-rich repeats, each {approx} 40 amino acids long. Previous studies showed that if the first repeat of the ligand-binding domain (encoded by exon 2) is deleted, the receptor fails to bind an anti-LDL receptor monoclonal antibody (IgG-C7) but continues to bind LDL with high affinity. Cultured fibroblasts from a Black South African Xhosa patient (TT) with the clinical syndrome of homozygous familial hypercholesterolemia demonstrated high-affinity cell-surface binding of {sup 125}I-labeled LDL but not {sup 125}I-labeled IgG-C7. previous haplotype analysis, using 10 restriction fragment length polymorphic sites, suggested that the patient inherited two identical LDL receptor alleles. The polymerase chain reaction technique was used to selectively amplify exon 2 of the LDL receptor gene from this patient. Sequence analysis of the amplified fragment disclosed a deletion of six base pairs that removes two amino acids, aspartic acid and glycine, from the first cysteine-rich ligand binding repeat. The mutation creates a new Pst I restriction site that can be used to detect the deletion. The existence of this mutant allele confirms that the epitope of IgG-C7 is located in the first cysteine-rich repeat and that this repeat is not necessary for LDL binding. The mutant gene produced a normally sized 120-kilodalton LDL receptor precursor protein that matured to the 160-kilodalton form at less than one-fourth the normal rate.

Leitersdorf, E.; Hobbs, H.H.; Fourie, A.M.; Jacobs, M.; Van Der Westhuyzen, D.R.; Coetzee, G.A. (Univ. of Texas Southwestern Medical Center, Dallas (USA))



Association of Lipoprotein Subfractions and Coronary Artery Calcium In Patient at Intermediate Cardiovascular Risk  

PubMed Central

More precise estimation of the atherogenic lipid parameters could improve identification of residual risk beyond what is possible using traditional lipid risk factors. The aim of the present study was to explore the association between advanced analysis of lipoprotein subfractions and the prevalence of coronary artery calcium. Consecutive participants at intermediate cardiovascular risk who were undergoing computed tomographic assessment of coronary calcium (calcium score) were included. Using a validated ultracentrifugation method (the vertical autoprofile II test), cholesterol in eluting lipoprotein subfractions [i.e., low- (LDL), very-low-, intermediate-, and high-density lipoprotein subclasses, lipoprotein (a), and predominant LDL distribution] was directly quantified. A total of 410 patients were included (29% women, mean age 57 years), of whom 297 (72.4%) had coronary artery calcium. LDL pattern B (predominance of small dense particles) emerged as an independent predictor of coronary calcium after adjustment for traditional risk factors (odds ratio 4.46, 95% confidence interval 1.19 to 16.7). However, after additional stratification for dyslipidemia, as defined by conventional lipid profiling, a statistically significant prediction was only retained for high-density lipoprotein subfraction 2 (odds ratio 3.45, 95% confidence interval 2.03 to 50.1) and “real” LDL (odds ratio 6.10, 95% confidence interval 1.26 to 23.41) in the normolipidemia group and for lipoprotein (a) (odds ratio 7.81, 95% confidence interval 1.41 to 43.5) in the dyslipidemic group. In conclusion, advanced assessment of the lipoprotein subfractions [i.e., LDL pattern B, high-density lipoprotein subfraction 2, “real” LDL, and lipoprotein (a)] using the vertical autoprofile II test provided additional information to that of conventional risk factors on the prevalence of coronary artery calcium in patients at intermediate cardiovascular risk. PMID:23141758

Jug, Borut; Papazian, Jenny; Lee, Robert; Budoff, Matthew J.



Lipolytic surface remnants of triglyceride-rich lipoproteins are cytotoxic to macrophages but not in the presence of high density lipoprotein. A possible mechanism of atherogenesis?  

PubMed Central

Hypertriglyceridemic (HTG) serum, lipolyzed in vitro by purified bovine milk lipoprotein lipase, was found to be cytotoxic to cultured macrophages. Surviving macrophages contained numerous lipid inclusions similar to those found in foam cells. Individual lipoprotein fractions isolated from the lipolyzed HTG serum, including HDL, were also cytotoxic. Lipolysis of isolated lipoprotein fractions (either HTG or normal) allowed localization of cytotoxicity to postlipolysis remnant VLDL and chylomicron particles. The presence of a critical concentration of HDL in either the lipolysis mixture or the culture dishes inhibited the cytotoxicity. Below this critical concentration HDL itself became cytotoxic, producing lipid inclusions in surviving macrophages. The lipid fraction of the cytotoxic remnants contained the cytotoxic factor(s); neither FFA nor lysolecithin alone could account for this cytotoxicity. Postprandial lipemic sera from subjects with a brisk chylomicron response, when lipolyzed in vitro, were cytotoxic to cultured macrophages; neither fasted sera from these subjects, nor postprandial sera from normolipidemic subjects with a normal chylomicron response, were cytotoxic. Postheparin (in vivo lipolyzed) serum and its isolated lipoprotein fractions obtained 30 min after heparin injection in subjects with HTG were shown to be cytotoxic to macrophages; by 60 min most of the cytotoxicity had disappeared. The postprandial and postheparin observations support an in vivo significance for remnant-associated cytotoxicity. We hypothesize that cytotoxic remnants of lipolyzed VLDL and chylomicrons may be one of the major atherogenic lipoproteins. Further, we suggest that inhibition of the cytotoxicity of these remnants may be one important way that HDL prevents atherosclerosis. Images PMID:2703536

Chung, B H; Segrest, J P; Smith, K; Griffin, F M; Brouillette, C G



Supernova Classes and Subclasses  

E-print Network

The discovery of many objects with unprecedented, amazing observational characteristics caused the last decade to be the most prolific period for the supernova research. Many of these new supernovae are transitional objects between existing classes, others well enter within the defined classes, but still show unique properties. This makes the traditional classification scheme inadequate to take into account the overall SN variety and, consequently, requires the introduction of new subclasses.

M. Turatto; S. Benetti; A. Pastorello



Fenofibrate Increases Very Low Density Lipoprotein Triglyceride Production Despite Reducing Plasma Triglyceride Levels in APOE*3-Leiden.CETP Mice*  

PubMed Central

The peroxisome proliferator-activated receptor alpha (PPAR?) activator fenofibrate efficiently decreases plasma triglycerides (TG), which is generally attributed to enhanced very low density lipoprotein (VLDL)-TG clearance and decreased VLDL-TG production. However, because data on the effect of fenofibrate on VLDL production are controversial, we aimed to investigate in (more) detail the mechanism underlying the TG-lowering effect by studying VLDL-TG production and clearance using APOE*3-Leiden.CETP mice, a unique mouse model for human-like lipoprotein metabolism. Male mice were fed a Western-type diet for 4 weeks, followed by the same diet without or with fenofibrate (30 mg/kg bodyweight/day) for 4 weeks. Fenofibrate strongly lowered plasma cholesterol (?38%) and TG (?60%) caused by reduction of VLDL. Fenofibrate markedly accelerated VLDL-TG clearance, as judged from a reduced plasma half-life of glycerol tri[3H]oleate-labeled VLDL-like emulsion particles (?68%). This was associated with an increased post-heparin lipoprotein lipase (LPL) activity (+110%) and an increased uptake of VLDL-derived fatty acids by skeletal muscle, white adipose tissue, and liver. Concomitantly, fenofibrate markedly increased the VLDL-TG production rate (+73%) but not the VLDL-apolipoprotein B (apoB) production rate. Kinetic studies using [3H]palmitic acid showed that fenofibrate increased VLDL-TG production by equally increasing incorporation of re-esterified plasma fatty acids and liver TG into VLDL, which was supported by hepatic gene expression profiling data. We conclude that fenofibrate decreases plasma TG by enhancing LPL-mediated VLDL-TG clearance, which results in a compensatory increase in VLDL-TG production by the liver. PMID:20501652

Bijland, Silvia; Pieterman, Elsbet J.; Maas, Annemarie C. E.; van der Hoorn, José W. A.; van Erk, Marjan J.; van Klinken, Jan B.; Havekes, Louis M.; van Dijk, Ko Willems; Princen, Hans M. G.; Rensen, Patrick C. N.



Clinical expression in heterozygotes of two frequent low density lipoprotein receptor gene mutations in the French Canadian population  

SciTech Connect

Five mutations in the low density lipoprotein (LDL) receptor (R) gene account for approximately 83% of cases of heterozygous familial hypercholesterolemia (hFH) in French Canadians in Quebec. The two most prevalent mutations are a >10kb deletion (10kb) of the promoter region resulting in a null allele (60.5% of cases) and a trp{sub 66}{r_arrow}gly missense mutation in exon 3 (ex3) resulting in a binding-defective R (11.7%). We have compared the phenotypic expression of these two mutations in 427 10kb hFH patients, 239 women (age 37.5 {plus_minus} 14.2 years) and 188 men (33.7 {plus_minus} 11.7) and 69 ex3 hFH patients, 42 women (40.6 {plus_minus} 14.3) and 27 men (36.8 {plus_minus}13.2). All data were analyzed separately for women and men. Tendon xanthomas were more prevalent in the 10kb (women 63%, men 68%) than in the ex3 patients (48%,48%). Total and LDL cholesterol were significantly higher in the 10kb patients with than without xanthomas but similar in ex3 patients. There were no significant differences in plasma lipoprotein concentrations between 10kb and ex3 patients with coronary artery disease (CAD) or between 10kb and ex3 patients without CAD. Among men with CAD, those with 10kb were significantly younger than those with ex3 (39.6 {plus_minus} 9.8, n=93 and 46.4 {plus_minus} 7.0, n=9, respectively). In both sexes, high plasma lipoprotein concentrations conferred an increased risk of CAD in 10kb but not in ex3 patients. Thus, as in homozygotes (previous study), the >10kb deletion is associated with more severe expression of FH than is the exon 3 mutation, although the plasma lipoprotein concentrations are not significantly different between the 10kb and ex3 heterozygotes. Since in homozygotes plasma cholesterol levels in 10kb are 60% higher than in ex3 patients, these observations suggest that the expression of the normal LDL-R allele compensates for the lack of a second allele in 10kb heterozygotes.

Roy, M.; Minnich, A.; Davignon, J. [Clinical Research Institute of Montreal, Quebec (Canada)



Understanding high-density lipoprotein function in disease: Recent advances in proteomics unravel the complexity of its composition and biology.  


Although the epidemiology of high-density lipoprotein (HDL) cholesterol and cardiovascular risk has been consistent, pharmacologic interventions to increase HDL-cholesterol by delaying HDL catabolism did not translate into reduction in cardiovascular risk. HDL particles are small, protein-rich when compared to other plasma lipoprotein classes. Latest progresses in proteomics technology have dramatically increased our understanding of proteins carried by HDL. In addition to proteins with well-established functions in lipid transport, iron transport proteins, members of the complement pathway, and proteins involved in immune function and acute phase response were repeatedly identified on HDL particles. With the unraveling of the complexity of the HDL proteome, different laboratories have started to monitor its changes in various disease states. In addition, dynamic aspects of HDL subgroups are being discovered. These recent studies clearly illustrate the promise of HDL proteomics for deriving new biomarkers for disease diagnosis and to measure the effectiveness of current and future treatment regimens. This review summarizes recent advances in proteomics and lipidomics helping to understand HDL function in health and disease. PMID:25107698

Birner-Gruenberger, Ruth; Schittmayer, Matthias; Holzer, Michael; Marsche, Gunther



The role of selenium in the secretion of very-low-density lipoprotein in the isolated perfused rat liver.  

PubMed Central

A recirculating liver perfusion system was used to study the effects of dietary selenium (Se) on the hepatic secretion of very-low-density lipoprotein (VLDL). The perfusate from livers of rats fed on a Se-deficient diet incorporated about 50% more [1-14C]oleic acid into triacylglycerol (TG) and cholesteryl esters (ChoEs) than did the perfusate from livers of rats fed on a Se-supplemented diet. Similarly, livers from rats fed the Se-deficient diet secreted more VLDL and incorporated about 60% more [1-14C]oleic acid into VLDL TG and ChoEs than did livers from rats fed the Se-supplemented diet. The liver perfusate from rats in the Se-deficient group also showed significantly decreased fatty acid oxidation. We conclude that Se is a potent modulator of lipoprotein metabolism. A primary action of Se deficiency appears to be a decrease in fatty acid oxidation and a stimulation of fatty acid esterification, leading to increased VLDL TG and ChoEs formation and secretion. PMID:1953666

Scott, R L; Kheshti, A; Heimberg, M; Wilcox, H G; Stone, W L



Phospholipase D activity underlies very-low-density lipoprotein (VLDL)-induced aldosterone production in adrenal glomerulosa cells.  


Aldosterone is the mineralocorticoid responsible for sodium retention, thus increased blood volume and pressure. Excessive production of aldosterone results in high blood pressure as well as renal disease, stroke, and visual loss via both direct effects and effects on blood pressure. Weight gain is often associated with increased blood pressure, but it remains unclear how obesity increases blood pressure. Obese patients typically have higher lipoprotein levels; moreover, some studies have suggested that aldosterone levels are also elevated and represent a link between obesity and hypertension. Very-low-density lipoprotein (VLDL) functions to transport triglycerides from the liver to peripheral tissues. Although previous studies have demonstrated that VLDL can stimulate aldosterone production, the mechanisms underlying this effect are largely unclear. Here we show for the first time that phospholipase D (PLD) is involved in VLDL-induced aldosterone production in both a human adrenocortical cell line (HAC15) and primary cultures of bovine zona glomerulosa cells. Our data also reveal that PLD mediates steroidogenic acute regulatory (StAR) protein and aldosterone synthase (CYP11B2) expression via increasing the phosphorylation (activation) of their regulatory transcription factors. Finally, by using selective PLD inhibitors, our studies suggest that both PLD1 and PLD2 isoforms play an important role in VLDL-induced aldosterone production. PMID:24956203

Tsai, Ying-Ying; Rainey, William E; Pan, Zhi-qiang; Frohman, Michael A; Choudhary, Vivek; Bollag, Wendy B



Hyperlipoproteinemia enhances susceptibility to acute disseminated Candida albicans infection in low-density-lipoprotein-receptor-deficient mice.  

PubMed Central

Recent studies have suggested the use of lipoproteins as an adjuvant treatment of lethal gram-negative infections. However, other important microorganisms for the etiology of sepsis, such as Candida species, grow better in lipid-rich environments. We investigated the effect of hyperlipoproteinemia on systemic candidiasis in low-density-lipoprotein-receptor-deficient (LDLR-/-) mice, in which the loss of the receptor results in a seven- to ninefold-higher plasma LDL level than that in their wild-type littermates (C57BL/6J). LDLR-/- mice died earlier, and the outgrowth of Candida albicans in the kidneys and livers of LDLR-/- mice was significantly higher compared with that of controls. After infection, circulating cytokine concentrations were significantly higher in LDLR-/- mice. In vitro, C. albicans grew better in plasma samples of LDLR-/- mice than in control plasma samples and peritoneal macrophages of LDLR-/- mice challenged with heat-killed C. albicans produced more cytokines than did those of controls. This latter phenomenon was probably due to increased binding of yeast cells to macrophages of LDLR-/- mice. These data suggest that hyperlipoproteinemia is deleterious in systemic candidiasis. PMID:9199434

Netea, M G; Demacker, P N; de Bont, N; Boerman, O C; Stalenhoef, A F; van der Meer, J W; Kullberg, B J



Induction of high-density-lipoprotein receptors in rat corpus luteum by human choriogonadotropin. Evidence of protein synthesis de novo.  

PubMed Central

The present studies investigated the specific binding of 125I-labelled high-density lipoprotein (125I-HDL) to plasma membranes. Golgi, rough endoplasmic reticulum and mitochondria/lysosomes, prepared from ovaries of rats injected with human choriogonadotropin (hCG) or 0.9% NaCl. Treatment in vivo with hCG resulted in 2-3-fold induction of 125I-HDL binding activity in all the subcellular organelles. The specific binding of HDL to various subcellular organelles was dependent on the amount of protein, lipoprotein concentration and incubation time. Equilibrium-binding studies revealed comparable Kd values (13-22 micrograms of HDL protein/ml) for HDL binding in all the subcellular organelles tested. Treatment with cycloheximide (2.0 mg/kg body wt.) before hCG administration abolished the induction of HDL receptors, suggesting the involvement of a protein-synthesis-dependent process in receptor induction. Analysis of equilibrium dissociation constants (Kd) for 125I-HDL binding in membranes from hCG-, cycloheximide-and saline-treated animals suggests that the increase in binding was due to an increase in the number of binding sites rather than a change in the affinity. Additionally, pretreatment with tunicamycin, an inhibitor of N-linked glycosylation, had no effect on hCG-mediated receptor induction, suggesting that glycosylation of the receptor may not be necessary for the interaction of HDL with its receptors. PMID:2822008

Ghosh, D K; Menon, K M



Increasing high-density lipoprotein cholesterol, inhibition of cholesteryl ester transfer protein, and heart disease risk reduction.  


Our purpose is to review recent research in the area of high-density lipoprotein (HDL) cholesterol raising and coronary artery disease (CAD) risk reduction. It is known that a decreased HDL cholesterol level is an important CAD risk factor and that raising HDL cholesterol has been associated with CAD risk reduction. A relative new strategy for raising HDL cholesterol, inhibition of cholesteryl ester transfer protein (CETP), is markedly effective. CETP inhibitors prevent the transfer of cholesteryl ester from HDL to triglyceride-rich lipoproteins in exchange for triglyceride. One inhibitor, torcetrapib, binds to CETP on HDL, markedly increases HDL cholesteryl ester, has no effect on fecal cholesterol excretion, but can raise blood pressure. A large clinical trial in patients with CAD who were taking atorvastatin was recently stopped prematurely because of excess mortality in those receiving torcetrapib versus placebo, and 2 other trials reported no benefit of torcetrapib on coronary atherosclerosis or carotid intima-media thickness as compared with subjects on atorvastatin alone. The adverse effects of torcetrapib may be compound specific, and because the crystal structure of CETP is now known, it should be possible to develop more optimal CETP inhibitors that do not form a nonproductive complex with CETP on the HDL particle, as has been reported for torcetrapib. Another alternative for increasing HDL levels is to develop more effective and better tolerated niacin preparations. PMID:18047849

Schaefer, Ernst J; Asztalos, Bela F



Different methods for particle diameter determination of low density and high density lipoproteins-Comparison and evaluation  

E-print Network

C-I inhibits lipoprotein lipase (LPL) mediated TAG- lipolysis (32). Thus reduced binding of VLDL1 to its receptor along with decreased lipolysis of VLDL1 creates an environment ideal for the formation of small dense LDL (Figure 1) (27). Triacylglycerol rich... Lipase (HL). In case of increased hepatic lipase function, rapid removal of TAG from LDL leads to the formation of small dense LDL particles. Thus the key players in this model for generating small dense LDL are HTAG, CETP and HL (27) (Figure 1...

Vaidyanathan, Vidya



Ethanol extract of propolis protects endothelial cells from oxidized low density lipoprotein-induced injury by inhibiting lectin-like oxidized low density lipoprotein receptor-1-mediated oxidative stress.  


Lectin-like oxidized low density lipoprotein receptor-1 (LOX-1), as the primary oxidized low-density lipoprotein (ox-LDL) receptor on endothelial cells, plays a crucial role in endothelial injury, which is a driving force in the initiation and development of atherosclerosis. Our previous studies have shown that ethanol extract of propolis (EEP) promotes reverse cholesterol transport and inhibits atherosclerotic lesion development. However, the protective effects of EEP against ox-LDL-induced injury in endothelial cells and the underlying mechanisms are still unknown. This study was designed to test the hypothesis that EEP attenuates ox-LDL-induced endothelial oxidative injury via modulation of LOX-1-mediated oxidative stress. Our results showed that exposure of human umbilical vein endothelial cells (HUVECs) to ox-LDL (100?mg/L) led to the decrease in cell viability and increase in lactate dehydrogenase (LDH) release, caspase-3 activation, and apoptosis, whereas pretreatment with EEP (7.5, 15 and 30?mg/L) protected against such damages in a dose-dependent manner. In addition, EEP mitigated ox-LDL uptake by HUVECs and attenuated ox-LDL-upregulated LOX-1 expression both at the mRNA and protein levels. Moreover, EEP suppressed the ox-LDL-induced oxidative stress as assessed by decreased nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation, reactive oxygen species (ROS), and malondialdehyde (MDA) generation as well as increased antioxidant enzyme activities. Similar results were observed in the anti-LOX-1 antibody or diphenyleneiodonium (DPI)-pretreated HUVECs. These data indicate that EEP may protect HUVECs from ox-LDL-induced injury and that the mechanism at least partially involves its ability to inhibit endothelial LOX-1 upregulation and subsequent oxidative stress. PMID:24962173

Fang, Yongqi; Li, Jinguo; Ding, Mingde; Xu, Xiaoyan; Zhang, Jiajun; Jiao, Peng; Han, Ping; Wang, Jiafu; Yao, Shutong



Low high-density lipoprotein cholesterol is a residual risk factor associated with long-term clinical outcomes in diabetic patients with stable coronary artery disease who achieve optimal control of low-density lipoprotein cholesterol.  


Diabetes mellitus is recognized an independent risk factor for coronary artery disease (CAD) and mortality. Clinical trials have shown that statins significantly reduce cardiovascular events in diabetic patients. However, residual cardiovascular risk persists despite the achievement of target low-density lipoprotein cholesterol (LDL-C) levels with statin. High-density lipoprotein cholesterol (HDL-C) is an established coronary risk factor that is independent of LDL-C levels. We evaluated the impact of HDL-C on long-term mortality in diabetic patients with stable CAD who achieved optimal LDL-C. We enrolled 438 consecutive diabetic patients who were scheduled for percutaneous coronary intervention between 2004 and 2007 at our institution. We identified 165 patients who achieved target LDL-C <100 mg/dl. Patients were stratified into two groups according to HDL-C levels (low HDL-C group, baseline HDL-C <40 mg/dl; high HDL-C group, ?40 mg/dl). Major adverse cardiac events (MACE) that included all-cause death, acute coronary syndrome, and target lesion revascularization were evaluated between the two groups. The median follow-up period was 946 days. The rate of MACE was significantly higher in diabetic patients with low-HDL-C who achieved optimal LDL-C (6.9 vs 17.9 %, log-rank P = 0.030). Multivariate Cox regression analysis showed that HDL-C is significantly associated with clinical outcomes (adjusted hazard ratio for MACE 1.33, 95 % confidence interval 1.01-1.75, P = 0.042). Low HDL-C is a residual risk factor that is significantly associated with long-term clinical outcomes among diabetic patients with stable CAD who achieve optimal LDL-C levels. PMID:23516028

Ogita, Manabu; Miyauchi, Katsumi; Miyazaki, Tadashi; Naito, Ryo; Konishi, Hirokazu; Tsuboi, Shuta; Dohi, Tomotaka; Kasai, Takatoshi; Yokoyama, Takayuki; Okazaki, Shinya; Kurata, Takeshi; Daida, Hiroyuki



Scavenger receptor BI facilitates hepatic very low density lipoprotein production in mice.  


Scavenger receptor BI (SR-BI) is a selective uptake receptor for HDL cholesterol but is also involved in the catabolism of apolipoprotein (apo)B-containing lipoproteins. However, plasma levels of apoB-containing lipoproteins increase following hepatic SR-BI overexpression, suggesting that SR-BI not solely mediates their catabolism. We therefore tested the hypothesis that hepatic SR-BI impacts on VLDL production. On day 7 following adenovirus (Ad)-mediated overexpression of SR-BI, VLDL-triglyceride and VLDL-apoB production rates were significantly increased (P < 0.001), whereas VLDL production was significantly lower in SR-BI knockout mice compared with controls (P < 0.05). In mice injected with AdSR-BI, hepatic cholesterol content increased (P < 0.001), microsomal triglyceride transfer protein activity was higher (P < 0.01) and expression of sterol-regulatory element binding protein (SREBP)2 and its target genes was decreased (P < 0.01). Conversely, in SR-BI knockout mice, microsomal triglyceride transfer protein activity was lower and expression of SREBP2 target genes was increased (P < 0.01). Finally, we demonstrate in vitro in isolated primary hepatocytes as well as in vivo that cholesterol derived from HDL and taken up via SR-BI into the liver can be resecreted within VLDL. These data indicate that hepatic SR-BI expression is linked to VLDL production, and within liver, a metabolic shunt might exist that delivers HDL cholesterol, at least in part, to a pool from which cholesterol is mobilized for VLDL production. These results might have implications for HDL-based therapies against atherosclerotic cardiovascular disease, especially with SR-BI as target. PMID:19723664

Wiersma, Harmen; Nijstad, Niels; Gautier, Thomas; Iqbal, Jahangir; Kuipers, Folkert; Hussain, M Mahmood; Tietge, Uwe J F



Scavenger receptor BI facilitates hepatic very low density lipoprotein production in mice  

PubMed Central

Scavenger receptor BI (SR-BI) is a selective uptake receptor for HDL cholesterol but is also involved in the catabolism of apolipoprotein (apo)B-containing lipoproteins. However, plasma levels of apoB-containing lipoproteins increase following hepatic SR-BI overexpression, suggesting that SR-BI not solely mediates their catabolism. We therefore tested the hypothesis that hepatic SR-BI impacts on VLDL production. On day 7 following adenovirus (Ad)-mediated overexpression of SR-BI, VLDL-triglyceride and VLDL-apoB production rates were significantly increased (P < 0.001), whereas VLDL production was significantly lower in SR-BI knockout mice compared with controls (P < 0.05). In mice injected with AdSR-BI, hepatic cholesterol content increased (P < 0.001), microsomal triglyceride transfer protein activity was higher (P < 0.01) and expression of sterol-regulatory element binding protein (SREBP)2 and its target genes was decreased (P < 0.01). Conversely, in SR-BI knockout mice, microsomal triglyceride transfer protein activity was lower and expression of SREBP2 target genes was increased (P < 0.01). Finally, we demonstrate in vitro in isolated primary hepatocytes as well as in vivo that cholesterol derived from HDL and taken up via SR-BI into the liver can be resecreted within VLDL. These data indicate that hepatic SR-BI expression is linked to VLDL production, and within liver, a metabolic shunt might exist that delivers HDL cholesterol, at least in part, to a pool from which cholesterol is mobilized for VLDL production. These results might have implications for HDL-based therapies against atherosclerotic cardiovascular disease, especially with SR-BI as target. PMID:19723664

Wiersma, Harmen; Nijstad, Niels; Gautier, Thomas; Iqbal, Jahangir; Kuipers, Folkert; Hussain, M. Mahmood; Tietge, Uwe J. F.



High density lipoproteins and prevention of experimental atherosclerosis with special reference to tree shrews.  


According to data obtained from epidemiological and experimental survey, serum HDL level is known to be correlated conversely with the incidence of atherosclerosis. Experimental data collected in this article explained part of its mechanism, which is described in four parts as follows: 1. The result of 3 successive experiments on experimental atherosclerosis in tree shrews (total of 96 animals available including 40 as the controls) showed that the serum HDL level had been kept persistantly to 69-88% of the total serum lipoproteins even after a high cholesterol intake for 32 weeks. The incidence of atheromatous lesions developed was only 0-9%, but the incidence of gall stone was very high, 48-84% by gross examination by the end of these experiments. 2. HDL are also capable of (1) promotion of monocyte migration activity; (2) enhancement of cholesterol clearance rate of aortic smooth muscle cells originally isolated from either rabbits or tree shrews; (3) inhibition of 20% of LDL degradation but with no inhibitory effect obtained on Ac-LDL degradation in the endothelial cells; (4) presence of specific binding sites for apo E free HDL on the surface of aortic smooth muscle cells from either rabbits or tree shrews which recognizes apo A1 as a ligand. 3. Data from 2 successive experiments in rabbits showed that HDL lipoproteins (mainly apo A1) possess an inhibitory effect on the development of atheromatous plaques, but not a very strong one. 4. The colesterol clearance effect of smooth muscle cells was markedly enhanced by apo A1/phospholipid liposomes (the apo A1 used was isolated from either rabbit's or tree shrew's serum) in vitro. PMID:2123379

She, M P; Xia, R Y; Ran, B F; Wong, Z L



High-density lipoprotein cholesterol function improves after successful treatment of psoriasis: a step forward in the right direction.  


There is epidemiological evidence that high-density lipoprotein (HDL) concentrations, or HDL "levels," exert protection from atherosclerosis, suggesting that HDL plays a role in vascular diseases. More accurate measures of HDL "function" are emerging, such as HDL efflux assays, which measure removal of cholesterol from peripheral tissues. Using this assay, we have demonstrated that psoriasis is associated with decreased HDL "levels" and HDL "function." The study by Holzer et al. in this issue demonstrates in an open-label, uncontrolled study that HDL function is impaired in psoriasis and improves after successful treatment of psoriasis. These findings underscore the notion that treatment of psoriasis likely extends beyond the skin and that a randomized controlled clinical trial is needed to confirm these findings. PMID:24518110

Mehta, Nehal N; Gelfand, Joel M



Mechanobiology of low-density lipoprotein transport within an arterial wall--impact of hyperthermia and coupling effects.  


The effects of hyperthermia, coupling attributes and property variations on Low-density lipoprotein (LDL) transport within a multi-layered wall while accounting for the fluid structure interaction (FSI) is analyzed in this work. To understand the potential impact of the hyperthermia process, thermo-induced attributes are incorporated, accounting for the plasma flow, mass transfer, as well as the elastic wall structure. The coupling effect of osmotic pressure, Soret and Dufour diffusion is discussed and their influence on LDL transport is examined, demonstrating that only the Soret effect needs to be accounted for. The effect of thermal expansion on changing the behavior of flow, mass transport, and elastic structure is illustrated and analyzed while incorporating the variations in the effective LDL diffusivity and consumption rate, as well as other dominating parameters. It is shown that hyperthermia results in an enhancement in LDL transport by increasing the concentration levels within the arterial wall. PMID:24183548

Chung, Stephen; Vafai, Kambiz



High density lipoprotein mediates anti-inflammatory transcriptional reprogramming of macrophages via the transcriptional repressor ATF3  

PubMed Central

High Density Lipoprotein (HDL) mediates reverse cholesterol transport and it is known to be protective against atherosclerosis. In addition, HDL has potent anti-inflammatory properties that may be critical for protection against other inflammatory diseases. The molecular mechanisms of how HDL can modulate inflammation, particularly in immune cells such as macrophages, remain poorly understood. Here we identify the transcriptional repressor ATF3, as an HDL-inducible target gene in macrophages that down-regulates the expression of Toll-like receptor (TLR)-induced pro-inflammatory cytokines. The protective effects of HDL against TLR-induced inflammation were fully dependent on ATF3 in vitro and in vivo. Our findings may explain the broad anti-inflammatory and metabolic actions of HDL and provide the basis for predicting the success of novel HDL-based therapies. PMID:24317040

De Nardo, Dominic; Labzin, Larisa I.; Kono, Hajime; Seki, Reiko; Schmidt, Susanne V.; Beyer, Marc; Xu, Dakang; Zimmer, Sebastian; Lahrmann, Catharina; Schildberg, Frank A.; Vogelhuber, Johanna; Kraut, Michael; Ulas, Thomas; Kerksiek, Anja; Krebs, Wolfgang; Bode, Niklas; Grebe, Alena; Fitzgerald, Michael L.; Hernandez, Nicholas J.; Williams, Bryan; Knolle, Percy; Kneilling, Manfred; Röcken, Martin; Lütjohann, Dieter; Wright, Samuel D.; Schultze, Joachim L.; Latz, Eicke



Pharmaceutical stabilization of mast cells attenuates experimental atherogenesis in low-density lipoprotein receptor-deficient mice  

PubMed Central

Mast cells (MCs) contribute to atherogenesis by releasing pro-inflammatory mediators to activate vascular cells and other inflammatory cells. This study examined whether MC activation or stabilization affects diet-induced atherosclerosis in low-density lipoprotein receptor-deficient (Ldlr?/?) mice. When Ldlr?/? mice consumed an atherogenic diet for 3 or 6 months, MC activation with compound 48/80 (C48/80) increased aortic arch intima and total lesion areas, and plasma total cholesterol, LDL, and triglyceride levels, whereas MC stabilization with cromolyn reduced these parameters. There were significant differences in arch intima and total lesion areas, and plasma total cholesterol, LDL, and triglyceride levels between C48/80-treated and cromolyn-treated mice. To examine a therapeutic application of cromolyn in atherosclerosis, we fed Ldlr?/? mice an atherogenic diet for 3 months followed by giving mice cromolyn for additional 3 months. Cromolyn did not affect aortic arch intima area, but significantly reduced lipid deposition in the thoracic-abdominal aortas. In aortic arches, however, cromolyn treatment significantly reduced lesion contents of Mac-3+ macrophages, CD4+ T cells, activated MCs, and lesion cell proliferation. While plasma total cholesterol and LDL levels increased and high-density lipoprotein (HDL) levels decreased from 3 months to 6 months of an atherogenic diet, cromolyn treatment decreased significantly plasma total cholesterol, LDL, and triglyceride levels and increased HDL levels above those of 3-month time point. These observations demonstrate that MC stabilization reduces lesion inflammation, ameliorates plasma lipid profiles, and may serve as a potential therapy for this cardiovascular disease. PMID:23880180

Wang, Jing; Sjöberg, Sara; Tia, Viviane; Secco, Blandine; Chen, Han; Yang, Min; Sukhova, Galina K.; Shi, Guo-Ping



Skeletal Muscle Insulin Resistance Associated with Cholesterol-Induced Activation of Macrophages Is Prevented by High Density Lipoprotein  

PubMed Central

Background Emerging evidence suggests that high density lipoprotein (HDL) may modulate glucose metabolism through multiple mechanisms including pancreatic insulin secretion as well as insulin-independent glucose uptake into muscle. We hypothesized that HDL may also increase skeletal muscle insulin sensitivity via cholesterol removal and anti-inflammatory actions in macrophages associated with excess adiposity and ectopic lipid deposition. Methods Human primary and THP-1 macrophages were treated with vehicle (PBS) or acetylated low density lipoprotein (acLDL) with or without HDL for 18 hours. Treatments were then removed, and macrophages were incubated with fresh media for 4 hours. This conditioned media was then applied to primary human skeletal myotubes derived from vastus lateralis biopsies taken from patients with type 2 diabetes to examine insulin-stimulated glucose uptake. Results Conditioned media from acLDL-treated primary and THP-1 macrophages reduced insulin-stimulated glucose uptake in primary human skeletal myotubes compared with vehicle (primary macrophages, 168±21% of basal uptake to 104±19%; THP-1 macrophages, 142±8% of basal uptake to 108±6%; P<0.05). This was restored by co-treatment of macrophages with HDL. While acLDL increased total intracellular cholesterol content, phosphorylation of c-jun N-terminal kinase and secretion of pro- and anti-inflammatory cytokines from macrophages, none were altered by co-incubation with HDL. Insulin-stimulated Akt phosphorylation in human skeletal myotubes exposed to conditioned media was unaltered by either treatment condition. Conclusion Inhibition of insulin-stimulated glucose uptake in primary human skeletal myotubes by conditioned media from macrophages pre-incubated with acLDL was restored by co-treatment with HDL. However, these actions were not linked to modulation of common pro- or anti-inflammatory mediators or insulin signaling via Akt. PMID:23437184

Reddy-Luthmoodoo, Medini; Natoli, Alaina K.; D’Souza, Wilissa; Meikle, Peter J.; Sviridov, Dmitri; Drew, Brian G.; Kingwell, Bronwyn A.



Protective Effects of Let-7a and Let-7b on Oxidized Low-Density Lipoprotein Induced Endothelial Cell Injuries  

PubMed Central

Lectin-like low-density lipoprotein receptor 1 (LOX-1) is a receptor for oxidized low density lipoprotein (oxLDL) in endothelial cells. The activation of LOX-1 by oxLDL stimulates the apoptosis and dysfunction of endothelial cells, and contributes to atherogenesis. However, the regulatory factors for LOX-1 are still unclear. MicroRNAs are small, endogenous, non-coding RNAs that regulate gene expressions at a post-transcriptional level. The let-7 family is the second microRNA been discovered, which plays important roles in cardiovascular diseases. Let-7a and let-7b were predicted to target LOX-1 3?-UTR and be highly expressed in endothelial cells. The present study demonstrated that LOX-1 was a target of let-7a and let-7b. They inhibited the expression of LOX-1 by targeting the positions of 310-316 in LOX-1 3?-UTR. Over-expression of let-7a and let-7b inhibited the oxLDL-induced endothelial cell apoptosis, NO deficiency, ROS over-production, LOX-1 upregulation and endothelial nitric oxide synthase (eNOS) downregulation. Moreover, we found that oxLDL treatment induced p38MAPK phosphorylation, NF-?B nuclear translocation, I?B degradation and PKB dephosphorylation. Let-7a or let-7b over-expression attenuated these alterations significantly. The present study may provide a new insight into the protective properties of let-7a and let-7b in preventing the endothelial dysfunction associated with cardiovascular disease, such as atherosclerosis. PMID:25247304

Bao, Mei-hua; Zhang, Yi-wen; Lou, Xiao-ya; Cheng, Yu; Zhou, Hong-hao



A predictor of atheroma progression in patients achieving very low levels of low-density lipoprotein cholesterol  

PubMed Central

An aggressive reduction in low-density lipoprotein cholesterol (LDL-C) with statins produces regression or stabilization of coronary artery plaques. However, after achieving very low levels of LDL-C, atheroma regression is not observed in all patients. The purpose of the present study was to evaluate the determinants of atheroma progression despite achieving very low levels of LDL-C. The effects of 8-month statin therapy on coronary atherosclerosis were evaluated using virtual histology intravascular ultrasound in the TRUTH study. Of these, 33 patients who achieved an on-treatment LDL-C level of <70 mg/dl were divided into 2 groups according to increase in plaque volume (progressors, n= 16) or decrease in plaque volume (regressors, n= 17) during an 8-month follow-up period. At the 8-month follow-up, serum LDL-C and apolipoprotein B levels were significantly lower in progressors than in regressors; however, significant increases in high-density lipoprotein cholesterol and apolipoprotein AI and decreases in high-sensitivity C-reactive protein and oxidized LDL were observed only in regressors. The changes in the n-3 to n-6 polyunsaturated fatty acid ratios significantly differed between the 2 groups. Multivariate regression analysis showed that a decrease in the eicosapentaenoic acid + docosahexaenoic acid/arachidonic acid ratio was a significant predictor associated with atheroma progression (?= -0.512, p= 0.004). In conclusions, n-3 to n-6 polyunsaturated fatty acid ratios affected coronary artery plaque progression and regression in patients who achieved very low levels of LDL-C during statin therapy. PMID:24224137

Nozue, Tsuyoshi; Yamamoto, Shingo; Tohyama, Shinichi; Fukui, Kazuki; Umezawa, Shigeo; Onishi, Yuko; Kunishima, Tomoyuki; Hibi, Kiyoshi; Terashima, Mitsuyasu; Michishita, Ichiro



Absence of clinical relationship between oxidized low density lipoproteins and diabetic peripheral neuropathy: a case control study  

PubMed Central

Background The pathophysiology of diabetic peripheral neuropathy (DPN) is complex and uncertain. A potential comorbidity in diabetes mellitus (DM) that may contribute to greater severity of DPN is a lipid disorder, such as with elevated cholesterol, low density lipoproteins or triglycerides. Oxidized low density lipoprotein (oxLDL) is a form of cholesterol that exerts direct toxic effects and contributes to pathogenicity through ligating a receptor called lectin-like receptor (LOX-1). Methods We examined plasma oxLDL levels in cohorts of patients with DPN with neuropathic pain (NeP), DPN patients without NeP, DM patients without DPN, patients with idiopathic peripheral neuropathy, and control subjects without DM or neuropathy. Our outcome measure was extent of oxLDL elevation, measured as fasting with Enzyme-Linked ImmunoSorbant Assay (ELISA) studies. Severity of diabetes was assessed using hemoglobin A1C measurements. Neuropathic severity was measured with the Utah Early Neuropathy Score (UENS). We hypothesized that DPN presence would be associated with oxLDL elevations. Results A total of 115 subjects (47 with DPN and NeP, 23 with DPN without NeP, 12 with diabetes only, 13 with idiopathic peripheral neuropathy, and 20 control subjects without diabetes or neuropathy) were studied. Duration of diabetes and diabetic glycemic measures were similar between populations with DM. Severity of DPN was similar between cohorts with DPN and NeP and DPN without NeP. Plasma oxLDL levels were similar between all cohorts, without any elevation in the presence of DM noted in any cohort with DM. Conclusions oxLDL levels are not different in patients with DPN, and their lack of greater presence suggests that any pathogenic role in human DPN is likely limited. PMID:24520839



Assembly and secretion of very low density lipoproteins containing apolipoprotein B48 in transfected McA-RH7777 cells. Lack of evidence that palmitoylation of apolipoprotein B48 is required for lipoprotein secretion.  


We examined the role of S-linked palmitoylation of human apolipoprotein (apo) B in the assembly and secretion of very low density lipoproteins using recombinant human apoB48. There are four free cysteine residues (Cys(1085), Cys(1396), Cys(1478), and Cys(1635)) within apoB48 that potentially can be palmitoylated. All four cysteine residues were substituted with serine by site-specific mutagenesis. The mutant protein was expressed in transfected rat hepatoma McA-RH7777 cells. Metabolic labeling of the stably transfected cells with iodopalmitic acid analog showed that the mutant apoB48 lacked palmitoylation. The lack of palmitoylation had little impact on the ability of apoB48 to assemble and secrete very low density lipoproteins or high density lipoproteins. Immunocytochemistry experiments using confocal microscopy failed to reveal any major alterations in the intracellular distribution of the mutant apoB48 at steady state. Pulse-chase analysis combined with subcellular fractionation showed no apparent deficiency in the movement of the mutant apoB48 protein from the endoplasmic reticulum to cis/medial Golgi. However, the mutant apoB48 lacking palmitoylation showed retarded movement toward the distal Golgi and increased association (>2-fold) with the membranes of the secretory compartments. A marginal decrease (by 15-20%) in secretion efficiency as compared with that of wild type apoB48 was also observed. These results suggest that lack of palmitoylation may influence the partitioning of apoB48 between microsomal membranes and microsomal lumen, but it does not compromise the ability of apoB48 to assemble lipoproteins. PMID:12582154

Vukmirica, Jelena; Tran, Khai; Liang, Xiquan; Shan, Jing; Yuan, Jane; Miskie, Brooke A; Hegele, Robert A; Resh, Marilyn D; Yao, Zemin



Low density lipoprotein receptor-related protein 1 expression correlates with cholesteryl ester accumulation in the myocardium of ischemic cardiomyopathy patients  

PubMed Central

Our hypothesis was that overexpression of certain lipoprotein receptors might be related to lipid accumulation in the human ischemic myocardium. Intramyocardial lipid overload contributes to contractile dysfunction and arrhythmias in cardiomyopathy. Thus, the purpose of this study was to assess the effect of hypercholesterolemic LDL and hypertrigliceridemic VLDL dose on LRP1 expression in cardiomyocytes, as well as the potential correlation between LRP1 expression and neutral lipid accumulation in the left ventricle tissue from ischemic cardiomyopathy patients. Cell culture experiments include control and LRP1-deficient cardiomyocytes exposed to lipoproteins under normoxic and hypoxic conditions. Explanted hearts from 18 ICM patients and eight non-diseased hearts (CNT) were included. Low density lipoprotein receptor-related protein 1 (LRP1), very low density lipoprotein receptor (VLDLR) and low density lipoprotein receptor (LDLR) expression was analyzed by real time PCR and Western blotting. Cholesteryl ester (CE), triglyceride (TG) and free cholesterol (FC) content was assess by thin layer chromatography following lipid extraction. Western blotting experiments showed that protein levels of LRP1, VLDLR and HIF-1? were significantly upregulated in ischemic hearts. Immunohistochemistry and confocal microscopy analysis showed that LRP1 and HIF-1? were upregulated in cardiomyocytes of ICM patients. In vitro studies showed that VLDL, LDL and hypoxia exerted an upregulatory effect on LRP1 expression and that LRP1 played a major role in cholesteryl ester accumulation from lipoproteins in cardiomyocytes. Myocardial CE accumulation strongly correlated with LRP1 levels in ischemic hearts. Taken together, our results suggest that LRP1 upregulation is key for myocardial cholesterol ester accumulation in ischemic human hearts and that LRP1 may be a target to prevent the deleterious effects of myocardial cholesterol accumulation in ischemic cardiomyopathy. PMID:22873206



Low density lipoprotein receptor-related protein 1 expression correlates with cholesteryl ester accumulation in the myocardium of ischemic cardiomyopathy patients.  


Our hypothesis was that overexpression of certain lipoprotein receptors might be related to lipid accumulation in the human ischemic myocardium. Intramyocardial lipid overload contributes to contractile dysfunction and arrhythmias in cardiomyopathy. Thus, the purpose of this study was to assess the effect of hypercholesterolemic LDL and hypertrigliceridemic VLDL dose on LRP1 expression in cardiomyocytes, as well as the potential correlation between LRP1 expression and neutral lipid accumulation in the left ventricle tissue from ischemic cardiomyopathy patients. Cell culture experiments include control and LRP1-deficient cardiomyocytes exposed to lipoproteins under normoxic and hypoxic conditions. Explanted hearts from 18 ICM patients and eight non-diseased hearts (CNT) were included. Low density lipoprotein receptor-related protein 1 (LRP1), very low density lipoprotein receptor (VLDLR) and low density lipoprotein receptor (LDLR) expression was analyzed by real time PCR and Western blotting. Cholesteryl ester (CE), triglyceride (TG) and free cholesterol (FC) content was assess by thin layer chromatography following lipid extraction. Western blotting experiments showed that protein levels of LRP1, VLDLR and HIF-1? were significantly upregulated in ischemic hearts. Immunohistochemistry and confocal microscopy analysis showed that LRP1 and HIF-1? were upregulated in cardiomyocytes of ICM patients. In vitro studies showed that VLDL, LDL and hypoxia exerted an upregulatory effect on LRP1 expression and that LRP1 played a major role in cholesteryl ester accumulation from lipoproteins in cardiomyocytes. Myocardial CE accumulation strongly correlated with LRP1 levels in ischemic hearts. Taken together, our results suggest that LRP1 upregulation is key for myocardial cholesterol ester accumulation in ischemic human hearts and that LRP1 may be a target to prevent the deleterious effects of myocardial cholesterol accumulation in ischemic cardiomyopathy. PMID:22873206

Cal, Roi; Juan-Babot, Oriol; Brossa, Vicenç; Roura, Santiago; Gálvez-Montón, Carolina; Portoles, Manolo; Rivera, Miguel; Cinca, Juan; Badimon, Lina; Llorente-Cortés, Vicenta



Hepatic metabolism of colloidal gold-low-density lipoprotein complexes in the rat: evidence for bulk excretion of lysosomal contents into bile  

SciTech Connect

Rats were treated with 17 alpha-ethinyl estradiol to induce high levels of low-density lipoprotein receptors in hepatocytes. When these rats were given intravenous injections of low-density lipoprotein-colloidal gold complexes, most of the gold (labeled with /sup 195/Au) appeared to be taken up by Kupffer cells, as were complexes of colloidal gold with albumin or polyvinylpyrrolidone. However, when these rats were also administered gadolinium chloride, which blocks Kupffer cell activity, most of the low-density lipoprotein-gold (but not gold complexed with albumin or polyvinylpyrrolidone) was taken up into hepatocytes by receptor-mediated endocytosis and concentrated in peribiliary lysosomes, as determined by electron microscopy. Colloidal gold taken up as a complex with low-density lipoprotein was excreted into the feces via the common bile duct at a maximal rate of about 5% daily, 4 to 12 days after injection. Thereafter, the rate of gold excretion fell off until reaching a plateau after 3 weeks. At this late time, most of the colloidal gold was shown by electron microscopy to be in Kupffer cells, whereas earlier (6 days after injection) it was contained mainly in older hepatocytic lysosomes, identified by lipofuscin granules. It is concluded that, in rats, hepatocytic lysosomes empty most of their contents into bile every week or two, apparently by exocytosis.

Renaud, G.; Hamilton, R.L.; Havel, R.J.



Correction of Apolipoprotein A-I-mediated Lipid Efflux and High Density Lipoprotein Particle Formation in Human Niemann-Pick Type C Disease Fibroblasts  

Technology Transfer Automated Retrieval System (TEKTRAN)

Impaired cell cholesterol trafficking in Niemann-Pick type C (NPC) disease results in the first known instance of impaired regulation of the ATP-binding cassette transporter A1 (ABCA1), a lipid transporter mediating the rate-limiting step in high density lipoprotein (HDL) formation, as a cause of lo...


Characterization of High Density Lipoprotein Particles in Familial Apolipoprotein A-I Deficiency With Premature Coronary Atherosclerosis, Corneal Arcus and Opacification, and Tubo-Eruptive and Planar Xanthomas  

Technology Transfer Automated Retrieval System (TEKTRAN)

We describe two male siblings with homozygous familial apolipoprotein (apo) A-I deficiency, markedly decreased high density lipoprotein (HDL) cholesterol levels, undetectable plasma apoA-1, tubo-eruptive and planar xanthomas, and mild corneal arcus and opacification. Sequencing of the apoA-I gene re...


A Targeted Mutation in the Murine Gene Encoding the High Density Lipoprotein (HDL) Receptor Scavenger Receptor Class B Type I Reveals Its Key Role in HDL Metabolism  

Microsoft Academic Search

Plasma high density lipoprotein (HDL), which protects against atherosclerosis, is thought to remove cholesterol from peripheral tissues and to deliver cholesteryl esters via a selective uptake pathway to the liver (reverse cholesterol transport) and steroidogenic tissues (e.g., adrenal gland for storage and hormone synthesis). Despite its physiologic and pathophysiologic importance, the cellular metabolism of HDL has not been well defined.

Attilio Rigotti; Bernardo L. Trigatti; Marsha Penman; Helen Rayburn; Joachim Herz; Monty Krieger



Changes in plasma antioxidant capacity and oxidized low-density lipoprotein levels in men after short-term cranberry juice consumption  

Microsoft Academic Search

Low-density lipoprotein (LDL) oxidation is closely implicated in the development of atherosclerotic cardiovascular disease (CVD), and thus, reducing LDL susceptibility to oxidation with antoxidants could be of importance in CVD prevention. Flavonoids, polyphenolic compounds found in a large selection of fruits and vegetables, have been characterized as having a strong antioxidant potential, and intake of flavonoid-rich foods has been related

Guillaume Ruel; Sonia Pomerleau; Patrick Couture; Benoît Lamarche; Charles Couillard



Colocalization of 15Lipoxygenase mRNA and Protein with Epitopes of Oxidized Low Density Lipoprotein in Macrophage-Rich Areas of Atherosclerotic Lesions  

Microsoft Academic Search

Oxidation of low density lipoprotein (LDL) enhances its atherogenicity, and inhibition of such oxidation decreases the rate of progression of atherosclerotic lesions. The mechanism of LDL oxidation in vivo remains uncertain, but in vitro studies have suggested that cellular lipoxygenases may play a role by initiating lipid peroxidation in LDL. In situ hybridization studies using a 15-lipoxygenase riboprobe and immunostaining

Seppo Yla-Herttuala; Michael E. Rosenfeld; Sampath Parthasarathy; Christopher K. Glass; Elliott Sigal; Joseph L. Witztum; Daniel Steinberg



The Effect of Aerobic Exercise on Total Cholesterol, High-Density Lipoprotein, Apolipoprotein B, Apolipoprotein A-I, and Percent Body Fat in Adolescent Females.  

ERIC Educational Resources Information Center

The effect of aerobic exercise on total cholesterol (TC), high-density lipoprotein (HDL), apolipoprotein B (Apo B), apolioprotein A-I (Apo A-I), and percent body fat in adolescent females was studied. The control subjects (n=86) were volunteers who had completed a physical education class at least six months prior to the commencement of the study,…

Lungo, Diane; And Others


Reduced susceptibility of low density lipoprotein (LDL) to lipid peroxidation after fluvastatin therapy is associated with the hypocholesterolemic effect of the drug and its binding to the LDL  

Microsoft Academic Search

Increased plasma cholesterol concentration in hypercholesterolemic patients is a major risk factor for atherosclerosis. The impaired removal of plasma low density lipoprotein (LDL) in these patients results in the presence of their LDL in the plasma for a long period of time and thus can contribute to its enhanced oxidative modification. In the present study we analyzed the effect of

Osamah Hussein; Sorina Schlezinger; Mira Rosenblat; Shlomo Keidar; Michael Aviram



A Single-Base Substitution in the Proximal Sp1 Site of the Human Low Density Lipoprotein Receptor Promoter as a Cause of Heterozygous Familial Hypercholesterolemia  

Microsoft Academic Search

We have identified a Finnish family with a typical phenotype of heterozygous familial hypercholesterolemia (FH) due to a single-base substitution in the proximal Sp1 binding site of the low density lipoprotein (LDL) receptor gene promoter. The mutation, a C --> T substitution at nucleotide -43, cosegregated with the FH phenotype in six available family members and abolished binding of Sp1

Ulla-Maija Koivisto; Jorma J. Palvimo; Olli A. Janne; Kimmo Kontula



Binding, Internalization, and Degradation of Low Density Lipoprotein by Normal Human Fibroblasts and by Fibroblasts from a Case of Homozygous Familial Hypercholesterolemia  

Microsoft Academic Search

Skin fibroblasts from a patient with homozygous familial hypercholesterolemia (HFH) were compared with normal skin fibroblasts with regard to binding, internalization, and degradation of iodinated human low density lipoprotein (LDL). Like other cell lines from HFH patients, the mutant cells showed no suppression of sterol synthesis by LDL. Surface binding, measured at 0 degrees to eliminate the appreciable internalization that

Olga Stein; David B. Weinstein; Yechezkiel Stein; Daniel Steinberg



Deficiency of Low Density Lipoprotein Receptors in Liver and Adrenal Gland of the WHHL Rabbit, an Animal Model of Familial Hypercholesterolemia  

Microsoft Academic Search

The WHHL (Watanabe heritable hyperlipidemic) rabbit has been proposed as an animal model for human familial hypercholesterolemia. Homozygous WHHL rabbits have marked increases in the plasma level of low density lipoprotein (LDL), removal of LDL from their plasma is delayed, and LDL receptors are absent from their cultured fibroblasts [Tanzawa, K., Shimada, Y., Kuroda, M., Tsujita, Y., Arai, M. &

Toru Kita; Michael S. Brown; Yoshio Watanabe; Joseph L. Goldstein



Hepatitis C virus core protein inhibits microsomal triglyceride transfer protein activity and very low density lipoprotein secretion: a model of viral-related steatosis  

Microsoft Academic Search

Liver steatosis, which involves accumula- tion of intracytoplasmic lipid droplets, is characteristic of hepatitis C virus (HCV) infection. By use of an in vivo transgenic murine model, we demonstrate that hepatic overexpression of HCV core protein interferes with the hepatic assembly and secretion of triglyceride- rich very low density lipoproteins (VLDL). Core expres- sion led to reduction in microsomal triglyceride




Genetic variation at the SLCO1B1 gene locus and low density lipoprotein cholesterol lowering response to pravastatin in the elderly  

Technology Transfer Automated Retrieval System (TEKTRAN)

Our goal was to determine whether genetic variation at genes affecting statin metabolism or targets of statin therapy would influence low density lipoprotein (LDL) cholesterol lowering with pravastatin, baseline heart disease, or cardiac endpoints on trial. We examined associations of single nucleot...


KIF6, LPA, TAS2R50, and VAMP8 genetic variation, low density lipoprotein cholesterol lowering response to pravastatin, and heart disease risk reduction in the elderly  

Technology Transfer Automated Retrieval System (TEKTRAN)

Single nucleotide polymorphisms (SNPs) at the KIF6 (kinesin like protein 6, rs20455 or 719Arg), LPA (lipoprotein(a), rs3798220), TAS2R50 (taste receptor type 2, member 50, rs1376251) and VAMP8 (vesicle-associated membrane protein 8, rs1010) have previously been associated with low density lipoprotei...


Up-regulated expression of type II very low density lipoprotein receptor correlates with cancer metastasis and has a potential link to ?-catenin in different cancers  

Microsoft Academic Search

BACKGROUND: Very low density lipoprotein receptor (VLDLR) has been considered as a multiple function receptor due to binding numerous ligands, causing endocytosis and regulating cellular signaling. Our group previously reported that enhanced activity of type II VLDLR (VLDLR II), one subtype of VLDLR, promotes adenocarcinoma SGC7901 cells proliferation and migration. The aim of this study is to explore the expression

Lei He; Yanjun Lu; Peng Wang; Jun Zhang; Chuanchang Yin; Shen Qu



Structure of HDL: Particle Subclasses and Molecular Components.  


A molecular understanding of high-density lipoprotein (HDL) will allow a more complete grasp of its interactions with key plasma remodelling factors and with cell-surface proteins that mediate HDL assembly and clearance. However, these particles are notoriously heterogeneous in terms of almost every physical, chemical and biological property. Furthermore, HDL particles have not lent themselves to high-resolution structural study through mainstream techniques like nuclear magnetic resonance and X-ray crystallography; investigators have therefore had to use a series of lower resolution methods to derive a general structural understanding of these enigmatic particles. This chapter reviews current knowledge of the composition, structure and heterogeneity of human plasma HDL. The multifaceted composition of the HDL proteome, the multiple major protein isoforms involving translational and posttranslational modifications, the rapidly expanding knowledge of the HDL lipidome, the highly complex world of HDL subclasses and putative models of HDL particle structure are extensively discussed. A brief history of structural studies of both plasma-derived and recombinant forms of HDL is presented with a focus on detailed structural models that have been derived from a range of techniques spanning mass spectrometry to molecular dynamics. PMID:25522985

Kontush, Anatol; Lindahl, Mats; Lhomme, Marie; Calabresi, Laura; Chapman, M John; Davidson, W Sean



The Effects of Apolipoprotein F Deficiency on High Density Lipoprotein Cholesterol Metabolism in Mice  

PubMed Central

Apolipoprotein F (apoF) is 29 kilodalton secreted sialoglycoprotein that resides on the HDL and LDL fractions of human plasma. Human ApoF is also known as Lipid Transfer Inhibitor protein (LTIP) based on its ability to inhibit cholesteryl ester transfer protein (CETP)-mediated transfer events between lipoproteins. In contrast to other apolipoproteins, ApoF is predicted to lack strong amphipathic alpha helices and its true physiological function remains unknown. We previously showed that overexpression of Apolipoprotein F in mice reduced HDL cholesterol levels by 20–25% by accelerating clearance from the circulation. In order to investigate the effect of physiological levels of ApoF expression on HDL cholesterol metabolism, we generated ApoF deficient mice. Unexpectedly, deletion of ApoF had no substantial impact on plasma lipid concentrations, HDL size, lipid or protein composition. Sex-specific differences were observed in hepatic cholesterol content as well as serum cholesterol efflux capacity. Female ApoF KO mice had increased liver cholesteryl ester content relative to wild type controls on a chow diet (KO: 3.4+/?0.9 mg/dl vs. WT: 1.2+/?0.3 mg/dl, p<0.05). No differences were observed in ABCG1-mediated cholesterol efflux capacity in either sex. Interestingly, ApoB-depleted serum from male KO mice was less effective at promoting ABCA1-mediated cholesterol efflux from J774 macrophages relative to WT controls. PMID:22363685

Lagor, William R.; Fields, David W.; Khetarpal, Sumeet A.; Kumaravel, Arthi; Lin, Wen; Weintraub, Nathaniel; Wu, Kaijin; Hamm-Alvarez, Sarah F.; Drazul-Schrader, Denise; de la Llera-Moya, Margarita; Rothblat, George H.; Rader, Daniel J.



Functionally Defective High-Density Lipoprotein and Paraoxonase: A Couple for Endothelial Dysfunction in Atherosclerosis  

PubMed Central

The endothelium is the primary target for biochemical or mechanical injuries caused by the putative risk factors of atherosclerosis. Endothelial dysfunction represents the ultimate link between atherosclerotic risk factors that promote atherosclerosis. HDL-C is thought to exert at least some parts of its antiatherogenic facilities via stimulating endothelial NO production, nearby inhibiting oxidative stress and inflammation. HDL-C is capable of opposing LDL's inductive effects and avoiding the ox-LDL's inhibition of eNOS. Paraoxonase 1 (PON1) is an HDL-associated enzyme esterase which appears to contribute to the antioxidant and antiatherosclerotic capabilities of HDL-C. “Healthy HDL,” namely the particle that contains the active Paraoxonase 1, has the power to suppress the formation of oxidized lipids. “Dysfunctional HDL,” on the contrary, has reduced Paraoxonase 1 enzyme activity and not only fails in its mission but also potentially leads to greater formation of oxidized lipids/lipoproteins to cause endothelial dysfunction. The association of HDL-C PON1 and endothelial dysfunction depends largely on the molecules with exact damaging effect on NO synthase coupling. Loss of nitric oxide bioavailability has a pivotal role in endothelial dysfunction preceding the appearance of atherosclerosis. Analyses of HDL-C and Paraoxonase1 would be more important in the diagnosis and treatment of atherosclerosis in the very near future. PMID:24222847

Eren, Esin; Yilmaz, Necat; Aydin, Ozgur



Emerging low-density lipoprotein (LDL) therapies: Management of severely elevated LDL cholesterol--the role of LDL-apheresis.  


Low-density lipoprotein (LDL)-apheresis is a Food and Drug Administration-approved treatment for patients with homozygous familial hypercholesterolemia (FH) or severe heterozygous FH. Based on electrochemical principles, it selectively removes apolipoprotein B-containing lipoproteins through extracorporeal precipitation with either heparin (Heparin-induced Extracorporeal LDL Precipitation, ie, HELP) or dextran sulfate (Liposorber). LDL-apheresis can lead to an acute decrease in LDL cholesterol (LDL-C) of 70%-80%, but there is a rapid rebound to baseline levels within approximately 2 weeks. LDL-apheresis is typically performed once-a-week in patients with homozygous FH and every other week in those with heterozygous FH to produce time-average LDL-C reductions of ? 40%. Side effects associated with LDL-apheresis include hypotension (later found to be due to concomitant use of angiotensin-converting enzyme inhibitors), nausea/vomiting, flushing, angina, and fainting. Posttreatment bleeding can occur secondary to heparin used during the procedure. Challenges associated with LDL-apheresis include vascular access often requiring an arteriovenous fistula (fistulas may clot and require revision over time), the time associated with each treatment session (2-4 hours), the frequency of treatment, and the scarcity of medical centers which perform LDL-apheresis. Given the nature of LDL-apheresis, randomized placebo controlled trials are nearly impossible, and virtually all studies of clinical benefit have been non-randomized investigations of small numbers of subjects. Nonetheless, results from those studies support the benefits of LDL-C reduction for reducing coronary atherosclerosis and cardiovascular events. PMID:23642325

McGowan, Mary P



Triglycerides and triglycerides to high-density lipoprotein cholesterol ratio are strong predictors of incident hypertension in Middle Eastern women.  


Dyslipidemia has been reported as a risk factor for incident hypertension in a few prospective studies, however, no study has specifically assessed different lipid measures including the lipid ratios, that is, total cholesterol (TC)/high-density lipoprotein cholesterol (HDL-C) and triglycerides (TGs)/HDL-C as predictors of hypertension among Middle Eastern women with high prevalences of dyslipidemia and hypertension. The study population consisted of 2831 non-hypertensive women, aged ? 20 years. We measured lipoproteins, and calculated non-HDL-C and the lipid ratios. The risk-factor-adjusted odds ratios for incident hypertension were calculated for every 1 standard deviation (s.d.) change in TC, log-transformed TG, HDL-C, non-HDL-C, TC/HDL-C and log-transformed TG/HDL-C using multivariate logistic regression analysis. Over a mean follow-up of 6.4 years, 397 women developed hypertension. An increase of 1 s.d. in TG, TC/HDL-C and TG/HDL-C increased the risk of incident hypertension by 16, 19 and 18%, respectively, and 1 s.d. increase in HDL-C decreased the risk of hypertension by 14% in the multivariable model (all P ? 0.05). In models excluding women with diabetes and central or general obesity, TG, TG/HDL-C and TC/HDL-C remained as independent predictors of incident hypertension. In conclusion, dyslipidemia, using serum TG and TG/HDL-C, in particular, may be useful in identification of women at risk of hypertension, even in those without diabetes and central or general obesity. PMID:21776016

Tohidi, M; Hatami, M; Hadaegh, F; Azizi, F



Interfacial Properties of High-Density Lipoprotein-like Lipid Droplets with Different Lipid and Apolipoprotein A-I Compositions  

PubMed Central

The surface properties of high-density lipoproteins (HDLs) are important because different enzymes bind and carry out their functions at the surface of HDL particles during metabolic processes. However, the surface properties of HDL and other lipoproteins are poorly known because they cannot be directly measured for nanoscale particles with contemporary experimental methods. In this work, we carried out coarse-grained molecular dynamics simulations to study the concentration of core lipids in the surface monolayer and the interfacial tension of droplets resembling HDL particles. We simulated lipid droplets composed of different amounts of phospholipids, cholesterol esters (CEs), triglycerides (TGs), and apolipoprotein A-Is. Our results reveal that the amount of TGs in the vicinity of water molecules in the phospholipid monolayer is 25–50% higher compared to the amount of CEs in a lipid droplet with a mixed core of an equal amount of TG and CE. In addition, the correlation time for the exchange of molecules between the core and the monolayer is significantly longer for TGs compared to CEs. This suggests that the chemical potential of TG is lower in the vicinity of aqueous phase but the free-energy barrier for the translocation between the monolayer and the core is higher compared to CEs. From the point of view of enzymatic modification, this indicates that TG molecules are more accessible from the aqueous phase. Further, our results point out that CE molecules decrease the interfacial tension of HDL-like lipid droplets whereas TG keeps it constant while the amount of phospholipids varies. PMID:23708359

Koivuniemi, Artturi; Sysi-Aho, Marko; Oreši?, Matej; Ollila, Samuli



Uptake of (/sup 3/H)vitamin D/sub 3/ from low and high density lipoproteins by cultured human fibroblasts  

SciTech Connect

The plasma distribution and cellular uptake of (/sup 3/H)vitamin D/sub 3/ was studied in vitro using cultured human fibroblasts. Incubation of (/sup 3/H)vitamin D/sub 3/ (cholecalciferol) with plasma followed by sequential ultracentrifugal fractionation of the lipoproteins indicated that 2-4% of the radioactivity associated with the very low density lipoprotein (VLDL), 12% with low density lipoprotein (LDL), and approximately 60% with the high density lipoprotein (HDL). The remaining radioactivity, 25%, was associated with the sedimented plasma fractions. By comparison, an average of 86% of the radioactivity from (/sup 3/H) 1,25-dihydroxycholecalciferol associated with the sedimented plasma fractions. The uptake of (/sup 3/H)vitamin D/sub 3/ from plasma, LDL, or HDL was studied in cultured human cells; uptake by normal fibroblasts was greatest from LDL and least from plasma. The cellular association of vitamin D/sub 3/ was time, concentration, and temperature dependent. At a concentration of 50 LDL/ml of medium, the uptake of (/sup 3/H)vitamin D/sub 3/ from LDL at 37/sup 0/C was rapid and reached a maximum at approximately 4 hr; it was slower from HDL but continued to increase slowly up to 24 hr. The significance of these in vitro findings is uncertain since much of the vitamin D/sub 3/ absorbed from the intestine reportedly associates with chylomicrons and is rapidly taken up by the liver.

Shireman, R.B.; Williams, D.; Remsen, J.F.



Activation of intestinal peroxisome proliferator-activated receptor-α increases high-density lipoprotein production  

PubMed Central

Aims Peroxisome Proliferator-Activated Receptor (PPAR) ? is a transcription factor controlling lipid metabolism in liver, heart, muscle and macrophages. PPAR?-activation increases plasma HDL-cholesterol and exerts hypotriglyceridemic actions via the liver. However, the intestine expresses PPAR?, produces HDL and chylomicrons and is exposed to diet-derived PPAR? ligands. Therefore, we examined the effects of PPAR?-activation on intestinal lipid and lipoprotein metabolism. Methods and Results The impact of PPAR?-activation was evaluated in term of HDL-related gene expression in mice, ex-vivo in human jejunal biopsies and in Caco-2/TC7 cells. ApoAI/HDL secretion, cholesterol esterification and trafficking were also studied in-vitro. In parallel to improving plasma lipid profiles and increasing liver and intestinal expression of fatty-acid-oxidation genes, treatment with the dual PPAR?/?-ligand GFT505 resulted in a more pronounced increase of plasma HDL compared to fenofibrate in mice. GFT505, but not fenofibrate, increased the expression of HDL-production genes such as apolipoprotein-AI and ATP-Binding-Cassette-A1 transporter in murine intestines. A similar increase was observed upon PPAR?-activation of human biopsies and Caco-2/TC7 cells. Additionally, HDL secretion by Caco-2/TC7 cells increased. Moreover, PPAR?-activation decreased the cholesterol-esterification capacity of Caco-2/TC7 cells, modified cholesterol trafficking and reduced apolipoprotein-B secretion. Conclusions PPAR?-activation reduces cholesterol esterification, suppresses chylomicron- and increases HDL-secretion by enterocytes. These results identify the intestine as a target organ of PPAR?-ligands with entero-hepatic tropism to reduce atherogenic dyslipidemia. PMID:22843443

Colin, Sophie; Briand, Olivier; Touche, Véronique; Wouters, Kristiaan; Baron, Morgane; Pattou, François; Hanf, Rémy; Tailleux, Anne; Chinetti, Giulia; Staels, Bart; Lestavel, Sophie



Testosterone increases the muscle protein synthesis rate but does not affect very-low-density lipoprotein metabolism in obese premenopausal women  

PubMed Central

Men and women with hyperandrogenemia have a more proatherogenic plasma lipid profile [e.g., greater triglyceride (TG) and total and low-density lipoprotein-cholesterol and lower high-density lipoprotein-cholesterol concentrations] than healthy premenopausal women. Furthermore, castration of male rats markedly reduces testosterone availability below normal and decreases plasma TG concentration, and testosterone replacement reverses this effect. Testosterone is, therefore, thought to be an important regulator of plasma lipid homeostasis. However, little is known about the effect of testosterone on plasma TG concentration and kinetics. Furthermore, testosterone is a potent skeletal muscle protein anabolic agent in men, but its effect on muscle protein turnover in women is unknown. We measured plasma lipid concentrations, hepatic very low density lipoprotein (VLDL)-TG and VLDL-apolipoprotein B-100 secretion rates, and the muscle protein fractional synthesis rate in 10 obese women before and after trandermal testosterone (1.25 g of 1% AndroGel daily) treatment for 3 wk. Serum total and free testosterone concentrations increased (P < 0.05) by approximately sevenfold in response to testosterone treatment, reaching concentrations that are comparable to those in women with hyperandrogenemia, but lower than the normal range for eugonadal men. Except for a small (?10%) decrease in plasma high-density lipoprotein particle and cholesterol concentrations (P < 0.04), testosterone therapy had no effect on plasma lipid concentrations, lipoprotein particle sizes, and hepatic VLDL-TG and VLDL-apolipoprotein B-100 secretion rates (all P > 0.05); the muscle protein fractional synthesis rate, however, increased by ?45% (P < 0.001). We conclude that testosterone is a potent skeletal muscle protein anabolic agent, but not an important regulator of plasma lipid homeostasis in obese women. PMID:22252942

Wang, Xuewen; Smith, Gordon I.; Patterson, Bruce W.; Reeds, Dominic N.; Kampelman, Janine; Magkos, Faidon



Impaired secretion of very low density lipoprotein-triglycerides by apolipoprotein E- deficient mouse hepatocytes.  

PubMed Central

To explore mechanisms underlying triglyceride (TG) accumulation in livers of chow-fed apo E-deficient mice (Kuipers, F., J.M. van Ree, M.H. Hofker, H. Wolters, G. In't Veld, R.J. Vonk, H.M.G. Princen, and L.M. Havekes. 1996. Hepatology. 24:241-247), we investigated the effects of apo E deficiency on secretion of VLDL-associated TG (a) in vivo in mice, (b) in isolated perfused mouse livers, and (c) in cultured mouse hepatocytes. (a) Hepatic VLDL-TG production rate in vivo, determined after Triton WR1339 injection, was reduced by 46% in apo E-deficient mice compared with controls. To eliminate the possibility that impaired VLDL secretion is caused by aspecific changes in hepatic function due to hypercholesterolemia, VLDL-TG production rates were also measured in apo E-deficient mice after transplantation of wild-type mouse bone marrow. Bone marrow- transplanted apo E-deficient mice, which do not express apo E in hepatocytes, showed normalized plasma cholesterol levels, but VLDL-TG production was reduced by 59%. (b) VLDL-TG production by isolated perfused livers from apo E-deficient mice was 50% lower than production by livers from control mice. Lipid composition of nascent VLDL particles isolated from the perfusate was similar for both groups. (c) Mass VLDL-TG secretion by cultured apo E-deficient hepatocytes was reduced by 23% compared with control values in serum-free medium, and by 61% in the presence of oleate in medium (0. 75 mM) to stimulate lipogenesis. Electron microscopic evaluation revealed a smaller average size for VLDL particles produced by apo E-deficient cells compared with control cells in the presence of oleate (38 and 49 nm, respectively). In short-term labeling studies, apo E-deficient and control cells showed a similar time-dependent accumulation of [3H]TG formed from [3H]glycerol, yet secretion of newly synthesized VLDL-associated [3H]TG by apo E-deficient cells was reduced by 60 and 73% in the absence and presence of oleate, respectively. We conclude that apo E, in addition to its role in lipoprotein clearance, has a physiological function in the VLDL assembly-secretion cascade. PMID:9389759

Kuipers, F; Jong, M C; Lin, Y; Eck, M; Havinga, R; Bloks, V; Verkade, H J; Hofker, M H; Moshage, H; Berkel, T J; Vonk, R J; Havekes, L M



Assessment of the role of sphingosine 1-phosphate and its receptors in high-density lipoprotein-induced stimulation of astroglial cell function.  

PubMed Central

It has been suggested that lipoproteins in the central nervous system are involved in the regulation of several neural functions independent of cholesterol metabolism as well as those related to lipid metabolism. We recently demonstrated that lipoproteins are carriers for sphingosine 1-phosphate (S1P). This raised the possibility that S1P mediates the neural cell functions induced by lipoproteins. In the current study, we examined the effects of plasma high-density lipoprotein (HDL) on astroglial cell functions, focusing especially on the role of the lipoprotein-associated S1P. In rat type I astrocytes or C6 glioma cells, similar to S1P, HDL stimulated DNA synthesis and mRNA expression of fibroblast growth factor-2, a potent neurotrophic factor, which was associated with the activation of extracellular signal-regulated kinase (ERK) in a pertussis toxin-sensitive manner. The data from fractionation studies of HDL indicated that S1P may be a major component for the activation of ERK. In C6 glioma cells, HDL also induced phospholipase C-dependent intracellular Ca(2+) mobilization. Desensitization of the C6 glioma cells with S1P abolished these HDL-induced actions. Furthermore, overexpression of S1P receptors in C6 glioma cells led to a significant enhancement of HDL-induced ERK activation and Ca(2+) mobilization. Thus, at least some HDL-induced actions may be mediated by cell-surface S1P receptors in astroglial cells. These results imply that S1P might partially mediate lipoprotein-induced cholesterol metabolism-independent neural cell functions in the central nervous system. PMID:12470300

Malchinkhuu, Enkhzol; Sato, Koichi; Muraki, Takeshi; Ishikawa, Koichi; Kuwabara, Atsushi; Okajima, Fumikazu



Low Serum High Density Lipoprotein Cholesterol Concentration is an Independent Predictor for Enhanced Inflammation and Endothelial Activation  

PubMed Central

Background Inflammation, endothelial activation and oxidative stress have been established as key events in the initiation and progression of atherosclerosis. High-density lipoprotein cholesterol (HDL-c) is protective against atherosclerosis and coronary heart disease, but its association with inflammation, endothelial activation and oxidative stress is not well established. Objectives (1) To compare the concentrations of biomarkers of inflammation, endothelial activation and oxidative stress in subjects with low HDL-c compared to normal HDL-c; (2) To examine the association and correlation between HDL-c and these biomarkers and (3) To determine whether HDL-c is an independent predictor of these biomarkers. Methods 422 subjects (mean age±SD = 43.2±11.9years) of whom 207 had low HDL-c concentrations (HDL-c <1.0mmol/L and <1.3mmol/L for males and females respectively) and 215 normal controls (HDL-c ?1.0 and ?1.3mmol/L for males and females respectively) were recruited in this study. The groups were matched for age, gender, ethnicity, smoking status, diabetes mellitus and hypertension. Fasting blood samples were collected for analysis of biomarkers of inflammation [high-sensitivity C-reactive protein (hsCRP) and Interleukin-6 (IL-6)], endothelial activation [soluble Vascular Cell Adhesion Molecule-1 (sVCAM-1), soluble Intercellular Adhesion Molecule-1 (sICAM-1) and E-selectin)] and oxidative stress [F2-Isoprostanes, oxidized Low Density Lipoprotein (ox-LDL) and Malondialdehyde (MDA)]. Results Subjects with low HDL-c had greater concentrations of inflammation, endothelial activation and oxidative stress biomarkers compared to controls. There were negative correlations between HDL-c concentration and biomarkers of inflammation (IL-6, p = 0.02), endothelial activation (sVCAM-1 and E-selectin, p = 0.029 and 0.002, respectively), and oxidative stress (MDA and F2-isoprostane, p = 0.036 and <0.0001, respectively). Multiple linear regression analysis showed HDL-c as an independent predictor of IL-6 (p = 0.02) and sVCAM-1 (p<0.03) after correcting for various confounding factors. Conclusion Low serum HDL-c concentration is strongly correlated with enhanced status of inflammation, endothelial activation and oxidative stress. It is also an independent predictor for enhanced inflammation and endothelial activation, which are pivotal in the pathogenesis of atherosclerosis and atherosclerosis-related complications. PMID:25614985

Wan Ahmad, Wan Nor Hanis; Sakri, Farah; Mokhsin, Atiqah; Rahman, Thuhairah; Mohd Nasir, Nadzimah; Abdul-Razak, Suraya; Md Yasin, Mazapuspavina; Mohd Ismail, Aletza; Ismail, Zaliha; Nawawi, Hapizah



Detection of a 58-kilodalton high density lipoprotein-binding protein in the membrane fraction of luteinized rat ovaries.  


The membrane fraction from the ovaries of pseudopregnant rats exhibits specific, high affinity binding of high density lipoproteins (HDL). Previous studies have indicated that HDL binding in this tissue is up-regulated by hCG and may be involved in supplying cholesterol as substrate for steroid hormone production. To characterize the HDL-binding activity, we solubilized the membrane proteins using 40 mM beta-octylglucoside and then separated them by electrophoresis on a 7% sodium dodecyl sulfate-polyacrylamide gel. The separated proteins were transferred to nitrocellulose sheets and subsequently incubated in the presence of [125I]apolipoprotein-E-free HDL. Autoradiography of the nitrocellulose revealed that the labeled HDL was bound to a single major band, with an apparent mol wt of 58,000 daltons. Neither reduction with beta-mercaptoethanol nor heat denaturation before separation on the gel affected the molecular size of the band, which indicates that it is probably a single polypeptide chain. The band was up-regulated in this tissue by in vivo treatment with 25 IU hCG in a time-dependent manner similar to the up-regulation of [125I]HDL-binding activity. In contrast to the binding of low density lipoprotein (LDL) to its receptor, the binding of HDL is independent of Ca+2. Incubation of the transferred proteins in the presence of [125I] Incubation of the transferred proteins in the presence of [125I]apolipoprotein-E-free HDL and either 5 mM CaCl2 or 15 mM EDTA had no effect on the appearance of the 58-kDa band. Furthermore, ligand blotting in the presence of a 100-fold excess of LDL did not affect the appearance of the band, whereas a 100-fold excess of apoliprotein-E-free HDL caused the disappearance of the band, indicating specificity for binding of HDL. Treatment of the sample with trypsin before electrophoresis also caused the band to disappear, revealing the protein nature of the band. These experiments indicate that the HDL receptor in luteinized rat ovaries is a 58,000-dalton protein. PMID:2108010

Ferreri, K; Menon, K M



Identification of the Best Anthropometric Predictors of Serum High- and Low-Density Lipoproteins using Machine Learning.  


Serum high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol levels are associated with risk factors for various diseases and are related to anthropometric measures. However, controversy remains regarding the best anthropometric indicators of the HDL and LDL cholesterol levels. The objectives of the present study were to identify the best predictors of HDL and LDL cholesterol using statistical analyses and two machine learning algorithms and to compare the predictive power of combined anthropometric measures in Korean adults. A total of 13014 subjects participated in the present study. The anthropometric measures were assessed with binary logistic regression to evaluate statistically significant differences between the subjects with normal and high LDL cholesterol levels and between the subjects with normal and low HDL cholesterol levels. Logistic regression (LR) and the naive Bayes algorithm (NB), which provides more reasonable and reliable results, were used in the analyses of the predictive power of individual and combined measures. The best predictor of HDL was the rib to hip ratio (p = <0.0001; odds ratio (OR) = 1.895; area under curve (AUC) = 0.681) in women and the waist to hip ratio (WHR) (p = <0.0001; OR = 1.624; AUC = 0.633) in men. In women, the strongest indicator of LDL was age (p = <0.0001; OR = 1.662; AUC by NB = 0.653; AUC by LR = 0.636). Among the anthropometric measures, the body mass index (BMI), WHR, forehead to waist ratio, forehead to rib ratio, and forehead to chest ratio were the strongest predictors of LDL; these measures had similar predictive powers. The strongest predictor in men was BMI (p = <0.0001; OR = 1.369; AUC by NB = 0.594; AUC by LR = 0.595). The predictive power of almost all individual anthropometric measures was higher for HDL than for LDL, and the predictive power for both HDL and LDL in women was higher than for men. A combination of anthropometric measures slightly improved the predictive power for both HDL and LDL cholesterol. The best indicator for HDL and LDL might differ according to the type of cholesterol and the gender. In women, but not men, age was the variable that strongly predicted HDL and LDL cholesterol levels. Our findings provide new information for the development of better initial screening tools for HDL and LDL cholesterol. PMID:25148675

Lee, Bum Ju; Kim, Jong Yeol



Imatinib mesylate stimulates low-density lipoprotein receptor-related protein 1-mediated ERK phosphorylation in insulin-producing cells.  


Low-density lipoprotein receptor-related protein 1 (LRP1) is an endocytic and multi-functional type I cell surface membrane protein, which is known to be phosphorylated by the activated platelet-derived growth factor receptor (PDGFR). The tyrosine kinase inhibitor imatinib, which inhibits PDGFR and c-Abl, and which has previously been reported to counteract ?-cell death and diabetes, has been suggested to reduce atherosclerosis by inhibiting PDGFR-induced LRP1 phosphorylation. The aim of the present study was to study LRP1 function in ?-cells and to what extent imatinib modulates LRP1 activity. LRP1 and c-Abl gene knockdown was performed by RNAi using rat INS-1 832/13 and human EndoC1-?H1 cells. LRP1 was also antagonized by treatment with the antagonist low-density lipoprotein receptor-related protein associated protein 1 (LRPAP1). We have used PDGF-BB, a PDGFR agonist, and apolipoprotein E (ApoE), an LRP1 agonist, to stimulate the activities of PDGFR and LRP1 respectively. Knockdown or inhibition of LRP1 resulted in increased hydrogen peroxide (H2O2)- or cytokine-induced cell death, and glucose-induced insulin release was lowered in LRP1-silenced cells. These results indicate that LRP1 function is necessary for ?-cell function and that LRP1 is adversely affected by challenges to ?-cell health. PDGF-BB, or the combination of PDGF-BB+ApoE, induced phosphorylation of extracellular-signal-regulated kinase (ERK), Akt and LRP1. LRP1 silencing blocked this event. Imatinib blocked phosphorylation of LRP1 by PDGFR activation but induced phosphorylation of ERK. LRP1 silencing blocked imatinib-induced phosphorylation of ERK. Sunitinib also blocked LRP1 phosphorylation in response to PDGF-BB and induced phosphorylation of ERK, but this latter event was not affected by LRP1 knockdown. siRNA-mediated knockdown of the imatinib target c-Abl resulted in an increased ERK phosphorylation at basal conditions, with no further increase in response to imatinib. Imatinib-induced cell survival of tunicamycin-treated cells was partially mediated by ERK activation. We have concluded that imatinib promotes LRP1-dependent ERK activation, possibly via inhibition of c-Abl, and that this could contribute to the pro-survival effects of imatinib on ?-cells. PMID:24865476

Fred, Rikard G; Boddeti, Santosh Kumar; Lundberg, Marcus; Welsh, Nils



Inhibition of the microsomal triglyceride transfer protein blocks the first step of apolipoprotein B lipoprotein assembly but not the addition of bulk core lipids in the second step.  


The microsomal triglyceride transfer protein (MTP) is required for assembly and secretion of the lipoproteins containing apolipoprotein B (apoB): very low density lipoproteins and chylomicrons. Evidence indicates that the subclasses of these lipoproteins that contain apoB-48 are assembled in a distinct two-step process; first a relatively lipid-poor primordial lipoprotein precursor is produced, and then bulk neutral lipids are added to form the core of these spherical particles. To determine if either step is mediated by MTP, a series of clonal cell lines stably expressing apoB-53 and MTP was established in non-lipoprotein-producing HeLa cells. MTP activity in these cells was approximately 30%, and apoB secretion was 7-33% of that in HepG2 cells on a molar basis. Despite having robust levels of triglyceride and phospholipid synthesis, these cell lines, as exemplified by HLMB53-59, secreted >90% of the apoB-53 on relatively lipid-poor particles in the density range of 1.063-1.21 g/ml. These results suggested that coexpression of MTP and apoB only reconstituted the first but not the second step in lipoprotein assembly. To extend this observation, additional studies were carried out in McArdle RH-7777 rat hepatoma cells, in which the second step of apoB-48 lipoprotein assembly is well defined. Treatment of these cells with the MTP photoaffinity inhibitor BMS-192951 before pulse labeling with [35S]methionine/cysteine led to an 85% block of both apoB-48 and apoB-100 but not apoAI secretion, demonstrating inhibition of the first step of lipoprotein assembly. After a 30-min [35S]methioneine/cysteine pulse labeling and 120 min of chase, all of the nascent apoB-48 was observed to have a density of high density lipoproteins (1.063-1.21 g/ml), indicating that only the first step of lipoprotein assembly had occurred. The addition of oleic acid to the cell culture media activated the second step as evidenced by the conversion of the apoB-48 high density lipoproteins to very low density lipoproteins (d < 1.006 g/ml) during an extended chase period. Inactivation of MTP after completion of the first step, but before stimulation of the second step by the addition of oleic acid, did not block this conversion. Thus, inhibition of MTP did not hinder the addition of bulk core lipid to the primordial lipoprotein precursor particles, indicating that MTP is not required for the second step of apoB-48 lipoprotein assembly. PMID:8955151

Gordon, D A; Jamil, H; Gregg, R E; Olofsson, S O; Borén, J



Peroxisome Proliferator-activated Receptor / Regulates Very Low Density Lipoprotein Production and Catabolism in  

E-print Network

and obesity in mice, have ele- vated levels of serum triglycerides primarily associated with very low density levels of serum triglycerides in mice on a high fat Western diet by modulating both VLDL production and LPL-mediated catabolism of VLDL-triglycerides and also suggest a potential thera- peutic role for PPAR

Omiecinski, Curtis


Caenorhabditis elegans reveals a FxNPxY-independent low-density lipoprotein receptor internalization mechanism mediated by epsin1  

PubMed Central

Low-density lipoprotein receptor (LDLR) internalization clears cholesterol-laden LDL particles from circulation in humans. Defects in clathrin-dependent LDLR endocytosis promote elevated serum cholesterol levels and can lead to atherosclerosis. However, our understanding of the mechanisms that control LDLR uptake remains incomplete. To identify factors critical to LDLR uptake, we pursued a genome-wide RNA interference screen using Caenorhabditis elegans LRP-1/megalin as a model for LDLR transport. In doing so, we discovered an unanticipated requirement for the clathrin-binding endocytic adaptor epsin1 in LDLR endocytosis. Epsin1 depletion reduced LDLR internalization rates in mammalian cells, similar to the reduction observed following clathrin depletion. Genetic and biochemical analyses of epsin in C. elegans and mammalian cells uncovered a requirement for the ubiquitin-interaction motif (UIM) as critical for receptor transport. As the epsin UIM promotes the internalization of some ubiquitinated receptors, we predicted LDLR ubiquitination as necessary for endocytosis. However, engineered ubiquitination-impaired LDLR mutants showed modest internalization defects that were further enhanced with epsin1 depletion, demonstrating epsin1-mediated LDLR endocytosis is independent of receptor ubiquitination. Finally, we provide evidence that epsin1-mediated LDLR uptake occurs independently of either of the two documented internalization motifs (FxNPxY or HIC) encoded within the LDLR cytoplasmic tail, indicating an additional internalization mechanism for LDLR. PMID:23242996

Kang, Yuan-Lin; Yochem, John; Bell, Leslie; Sorensen, Erika B.; Chen, Lihsia; Conner, Sean D.



The Structure and Function of Serum Opacity Factor: A Unique Streptococcal Virulence Determinant That Targets High-Density Lipoproteins  

PubMed Central

Serum opacity factor (SOF) is a virulence determinant expressed by a variety of streptococcal and staphylococcal species including both human and animal pathogens. SOF derives its name from its ability to opacify serum where it targets and disrupts the structure of high-density lipoproteins resulting in formation of large lipid vesicles that cause the serum to become cloudy. SOF is a multifunctional protein and in addition to its opacification activity, it binds to a number of host proteins that mediate adhesion of streptococci to host cells, and it plays a role in resistance to phagocytosis in human blood. This article will provide an overview of the structure and function of SOF, its role in the pathogenesis of streptococcal infections, its vaccine potential, its prevalence and distribution in bacteria, and the molecular mechanism whereby SOF opacifies serum and how an understanding of this mechanism may lead to therapies for reducing high-cholesterol concentrations in blood, a major risk factor for cardiovascular disease. PMID:20671930

Courtney, Harry S.; Pownall, Henry J.



Detection of the low density lipoprotein (LDL) receptor on nitrocellulose paper with colloidal gold-LDL conjugates  

SciTech Connect

Gold-low density lipoprotein (LDL) conjugates were used to detect the LDL receptor on nitrocellulose paper. Solubilized rat liver membrane proteins were subjected to electrophoresis and electroblotted onto nitrocellulose paper. The receptor was then detected as a red band (within 10 min) by overlaying with the LDL conjugates. The coloration was prevented by unlabeled LDL, EDTA, and suramin but not by unlabeled HDL3. In the dot blot assay, detection with the colloidal gold-LDL conjugates was as sensitive as both the autoradiographic method with /sup 125/I-labeled LDL and the biotinylated LDL method; the estimated limit of detection by scanning densitometry was 1.6 femtomoles of receptor protein. When the coloration obtained with the colloidal gold-LDL conjugates was intensified by photochemical silver staining, down to 200 attomoles of the LDL receptor could be detected. In this assay, the EDTA-sensitive binding of colloidal gold-LDL to solubilized hepatic membrane proteins was 12 times higher for rats treated with 17 alpha-EE than for normal rats. The use of colloidal gold-LDL conjugates is therefore a very easy, safe, inexpensive, fast and sensitive method for the detection of the LDL receptor on nitrocellulose paper. Furthermore, with silver staining and scanning densitometry, the colloidal gold-LDL conjugates could be used in a dot blot assay to quantify tissue and cell LDL receptors down to attomolar levels.

Roach, P.D.; Zollinger, M.; Nol, S.P.



The low-density lipoprotein receptor-related protein 1 and amyloid-? clearance in Alzheimer’s disease  

PubMed Central

Accumulation and aggregation of amyloid-? (A?) peptides in the brain trigger the development of progressive neurodegeneration and dementia associated with Alzheimer’s disease (AD). Perturbation in A? clearance, rather than A? production, is likely the cause of sporadic, late-onset AD, which accounts for the majority of AD cases. Since cellular uptake and subsequent degradation constitute a major A? clearance pathway, the receptor-mediated endocytosis of A? has been intensely investigated. Among A? receptors, the low-density lipoprotein receptor-related protein 1 (LRP1) is one of the most studied receptors. LRP1 is a large endocytic receptor for more than 40 ligands, including apolipoprotein E, ?2-macroglobulin and A?. Emerging in vitro and in vivo evidence demonstrates that LRP1 is critically involved in brain A? clearance. LRP1 is highly expressed in a variety of cell types in the brain including neurons, vascular cells and glial cells, where LRP1 functions to maintain brain homeostasis and control A? metabolism. LRP1-mediated endocytosis regulates cellular A? uptake by binding to A? either directly or indirectly through its co-receptors or ligands. Furthermore, LRP1 regulates several signaling pathways, which also likely influences A? endocytic pathways. In this review, we discuss how LRP1 regulates the brain A? clearance and how this unique endocytic receptor participates in AD pathogenesis. Understanding of the mechanisms underlying LRP1-mediated A? clearance should enable the rational design of novel diagnostic and therapeutic strategies for AD. PMID:24904407

Kanekiyo, Takahisa; Bu, Guojun



Association of High Density Lipoprotein with Platelet to Lymphocyte and Neutrophil to Lymphocyte Ratios in Coronary Artery Disease Patients  

PubMed Central

Background. We aimed to evaluate a relationship between platelet-lymphocyte ratio (PLR) and neutrophil-lymphocyte ratio (NLR) with high density lipoprotein (HDL) cholesterol levels in coronary artery disease (CAD) patients. Methods. A total of 354 patients with angiographically confirmed coronary blockages were enrolled in the study. Hematological indices and lipid profiling data of all the patients were collected. Results. We have observed significant association between HDL and PLR (P = 0.008) and NLR (P = 0.009); however no significant relationship was obtained with HDL and isolated platelet (P = 0.488), neutrophil (P = 0.407), and lymphocyte (P = 0.952) counts in CAD patients. The association was subjected to gender specific variation as in males PLR (P = 0.024) and NLR (P = 0.03) were highly elevated in low HDL patients, whereas in females the elevation could not reach the statistically significant level. The PLR (217.47 versus 190.3; P = 0.01) and NLR (6.33 versus 5.10; P = 0.01) were significantly higher among the patients with acute coronary syndrome. In young patients the PLR (P = 0.007) and NLR (P = 0.001) were inversely associated with HDL, whereas in older population only NLR (P = 0.05) had showed a significant association. Conclusion. We conclude that PLR and NLR are significantly elevated in CAD patients having low HDL levels. PMID:25478231

Prajapati, Jayesh H.; Sahoo, Sibasis; Nikam, Tushar; Shah, Komal H.; Maheriya, Bhumika; Parmar, Meena



Low-density lipoprotein receptor-related protein 1: a physiological A? homeostatic mechanism with multiple therapeutic opportunities  

PubMed Central

Low-density lipoprotein receptor-related protein-1 (LRP1) is the main cell surface receptor involved in brain and systemic clearance of the Alzheimer's disease (AD) toxin amyloid-beta (A?). In plasma, a soluble form of LRP1 (sLRP1) is the major transport protein for peripheral A?. LRP1 in brain endothelium and mural cells mediates A? efflux from brain by providing a transport mechanism for A across the blood-brain barrier (BBB). sLRP1 maintains a plasma ‘sink’ activity for A? through binding of peripheral A? which in turn inhibits re-entry of free plasma A? into the brain. LRP1 in the liver mediates systemic clearance of A?. In AD, LRP1 expression at the BBB is reduced and A? binding to circulating sLRP1 is compromised by oxidation. Cell surface LRP1 and circulating sLRP1 represent druggable targets which can be therapeutically modified to restore the physiological mechanisms of brain A? homeostasis. In this review, we discuss how increasing LRP1 expression at the BBB and liver with lifestyle changes, statins, plant-based active principles and/or gene therapy on one hand, and how replacing dysfunctional plasma sLRP1 on the other regulate A? clearance from brain ultimately controlling the onset and/or progression of AD. PMID:22820095

Sagare, Abhay P.; Deane, Rashid; Zlokovic, Berislav V.



Characterization of a receptor for oxidized low-density lipoproteins on rat Kupffer cells: similarity to macrosialin.  

PubMed Central

Rat liver Kupffer cell membranes contain a protein that recognizes specifically oxidized low-density lipoproteins (oxLDL). Visualization after blotting under reducing conditions indicates that the receptor is a monomeric protein, with an estimated molecular mass of 115-120 kDa. N-Glycosidase F and endoglycosidase F treatment resulted in a fall in estimated molecular mass of 24 and 11 kDa respectively, whereas O-glycosidase was ineffective. No effect on the extent of interaction with oxLDL was noticed, suggesting that glycans are not essential for ligand recognition. Using a polyclonal antibody to mouse macrosialin, we visualized macrosialin on blot, and compared this glycoprotein with the oxLDL-binding protein. It appears that the two glycoproteins have a similar molecular mass and are comparably affected by treatment with the different glycosidases. Incubation with trypsin resulted in a reduction in the estimated molecular mass of about 25 kDa for both the oxLDL-binding protein and macrosialin. These results indicate that the oxLDL-binding protein and macrosialin are identical, suggesting a role for macrosialin in modified LDL catabolism. PMID:9065757

Van Velzen, A G; Da Silva, R P; Gordon, S; Van Berkel, T J



Unsaturated fatty alcohol derivatives of olive oil phenolic compounds with potential low-density lipoprotein (LDL) antioxidant and antiobesity properties.  


A new route for the synthesis of fatty alcohol derivatives of hydroxytyrosol and other olive oil phenolic compounds was developed to allow the preparation of unsaturated derivatives. The biological activity of synthesized compounds was evaluated. Most of the compounds presented a significant antioxidant activity on low-density lipoprotein (LDL) particles. The activity of the tested products was significantly influenced by the number and position of unsaturations as well as modifications on the polar head of the synthesized compounds. Some of them presented modulation of food intake in rats and, due to their molecular similarity with CB(1) endogenous ligands, the endocannabinoid system and PPAR-? were also evaluated as potential targets. The pharmacodynamics could not be totally explained by CB(1) and PPAR-? receptor interactions because only two of the four compounds with biological activity showed a CB(1) activity and all of them presented low PPAR-? affinity, not justifying its whole in vivo activity. The hydroxytyrosol linoleylether (7) increased LDL resistance to oxidation with a capacity similar to that of hydroxytyrosol and was the most active in vivo compound with a hypophagic effect comparable to that of oleoylethanolamine. We consider that this compound could be a good lead compound for future drug development in obesity treatments. PMID:22220510

Cotrim, Bruno Almeida; Joglar, Jesús; Rojas, M Jesús L; del Olmo, Juan Manuel Decara; Macias-González, Manuel; Cuevas, Miguel Romero; Fitó, Montserrat; Muñoz-Aguayo, Daniel; Planells, María Isabel Covas; Farré, Magí; de Fonseca, Fernando Rodríguez; de la Torre, Rafael



The effect of nutritional supplements on serum high-density lipoprotein cholesterol and apolipoprotein A-I.  


One of the factors contributing to the increased risk of developing premature atherosclerosis is low plasma concentrations of high-density lipoprotein (HDL) cholesterol. Multiple potential mechanisms account for the cardioprotective effects of HDL and its main protein apolipoprotein A-I (apo A-I). Diet has an important role in modulating HDL cholesterol level. The widespread use of nutritional supplements may also alter the biology of HDL. In this review, we discuss the effect of select nutritional supplements on serum HDL cholesterol and apo A-I levels. Some nutritional supplements, such as phytosterols, soy proteins, and black seed extracts, may increase HDL cholesterol levels, while others such as cholic acid and high doses of commonly used antioxidant vitamins may downregulate HDL cholesterol levels and reduce its cardioprotection. Multiple mechanisms are involved in the regulation of HDL levels, so changes in production and clearance of HDL may have different clinical implications. The clinical relevance of the changes in HDL and apo A-I caused by nutrient supplementation needs to be tested in controlled clinical trials. PMID:24604774

Mooradian, Arshag D; Haas, Michael J



Inhibition of oxidation of human low-density lipoproteins by phenolic substances in different essential oils varieties.  


Phenolics antioxidant phytochemicals have been recently implicated for the lower rates of cardiac disease mortality among people consuming a Mediterranean diet. Essential oils are natural products extracted from vegetable materials, which can be used as antibacterial, antifungal, antioxidants, and anti-carcinogenic agents or to preserve and give specific flavors to foods. The activities of 23 selected essential oils in inhibiting the copper-catalyzed oxidation of human-low-density lipoproteins (LDL) were determined in vitro. LDL oxidation was inhibited between 6, 2, and 83% by 2 microM (GAE) total phenolics. The relative inhibition of LDL oxidation was used to categorize the essential oils into four groups below 2% when they contained methylchavicol, anethol, p-cymen, apiole, cinnamic ether; 6-10% if they possessed a majority of carvacrol, thymol, p-cymene, or vanillin; 10-50% for moderate amounts of thymol, carvacrol, cuminol, or eugenol; and 50-100% when eugenol is the major component. Total phenol content of essential oils gave a correlation with LDL antioxidant activity of r = 0.75. The Activity of each phenolics compound could play a role in protecting LDL against oxidation if the substance is absorbed by the body. PMID:10995274

Teissedre, P L; Waterhouse, A L



Double seronegative myasthenia gravis with low density lipoprotein-4 (LRP4) antibodies presenting with isolated ocular symptoms.  


The detection of low density lipoprotein-4 (LRP4) antibodies in double seronegative (dSN) myasthenia gravis (MG) patients has provided new insights in the diagnosis and treatment of MG. However, there are limited data regarding the clinical presentation and treatment response in dSN MG patients with LRP4-antibodies. We present a case series of three Caucasian dSN MG patients with positive LRP4-antibodies sharing a common ethnic background that presented with isolated ocular symptoms (MGFA I). The demographic and clinical characteristics, the diagnostic work-up as well as the treatment response during a follow-up period of 12-24 months are described in detail. All patients were treated successfully with acetylcholinesterase inhibitors (AcheI) and prednisone with two exhibiting full remission of their symptoms, while the remaining exhibited mild residual diplopia. Notably, we documented no signs of generalized disease progression, while no patient required immunosuppressive treatment. In conclusion, the distinct clinical phenotype of our patients highlights the clinical relevance of screening for LRP4-antibodies in patients presenting with isolated ocular MG independent of age and gender, since it may lead to the timely diagnosis of MG and prompt initiation of effective therapy with ACheI and corticosteroids. PMID:25248951

Tsivgoulis, Georgios; Dervenoulas, Georgios; Kokotis, Panagiotis; Zompola, Christina; Tzartos, John S; Tzartos, Socrates J; Voumvourakis, Konstantinos I



Secondary structure and thermal behavior of trypsin-treated low-density lipoproteins from human serum, studied by circular dichroism.  


Low-density lipoproteins (LDL) were prepared from the serum of normolipidemic men on normal diets with or without supplemental beta-carotene. LDL were subjected to limited hydrolysis (5 h at 37 degrees C) with trypsin (enzyme:protein, 1:40 w/w), and their digested products separated by gel filtration. The trypsin-treated LDL contained about 80% of the original protein and essentially all of the original lipids of native LDL. The circular dichroic spectrum of trypsin-treated LDL below 240 nm resembled that of native LDL, except that the magnitudes of the ellipticity were smaller, corresponding to 25 and 33% helical content, respectively. The lower content of helix in trypsin-treated LDL suggests that certain helical regions in apolipoprotein B are sensitive to tryptic attack; however, a major portion of the helical structure of the apolipoprotein is resistant. The thermal stability of helix in trypsin-treated LDL resembled that of native LDL, suggesting that removal of the trypsin-accessible regions of the apolipoprotein has little or no effect on the forces stabilizing the remaining helices. Data on the induced circular dichroism of beta-carotene, an intrinsic probe of the neutral lipid core, showed a reduced transition temperature for cholesteryl esters after trypsin treatment. This finding suggests that the trypsin-accessible regions of apolipoprotein B may influence the fluidity of the core. PMID:6626567

Chen, G C; Chapman, M J; Kane, J P



A Numerical Computation Model for Low-Density Lipoprotein (LDL) Aggregation and Deposition in the Human Artery  

NASA Astrophysics Data System (ADS)

Cholesterol caused cardiovascular events are commonly seen in human lives. These events are primarily believed to be caused by the built up of particles like low-density lipoprotein (LDL). When a large number of LDL circulates in the blood, it can gradually build up in the inner walls of the arteries. A thick, hard deposit plaque can be formed together with other substances. This type of plaque may clog those arteries and cause vascular problems. Clinical evidences suggest that LDL is related to cardiovascular events and the progression of coronary heart disease is due to its aggregation and deposition. This study presents an investigation of LDL aggregation and deposition based on particulate flow. A soft-sphere based particulate computational flow model is developed to represent LDL suspending in plasma. The transport, collision and adhesion phenomena of LDL particles are simulated to examine the physics involved in aggregation and deposition. A multiple-time step discrete-element approach is presented for efficiently simulating large number of LDL particles and their interactions. The roles the quality and quantity the LDL playing in the process of aggregation and deposition are determined. The study provides a new perspective for improving the understanding of the fundamentals as related to these particle-caused cardiovascular events.

Zhao, Yongli; Cai, Shaobiao; Ratner, Albert



Capsaicin protects endothelial cells and macrophage against oxidized low-density lipoprotein-induced injury by direct antioxidant action.  


Atherosclerosis is a chronic inflammatory vascular disease. It is characterized by endothelial dysfunction, lipid accumulation, leukocyte activation, and the production of inflammatory mediators and reactive oxygen species (ROS). Capsaicin, a biologically active compound of the red pepper and chili pepper, has several anti-oxidant, anti-inflammatory, anti-cancer, and hypolipidemic biological effects. However, its protective effects on foam cell formation and endothelial injury induced by oxidized low-density lipoprotein (oxLDL) remain unclear. In this study, we evaluated the anti-oxidative activity of capsaicin, and determined the mechanism by which capsaicin rescues human umbilical vein endothelial cells (HUVECs) from oxLDL-mediated dysfunction. The anti-oxidative activity of capsaicin was defined by Apo B fragmentation and conjugated diene production of the copper-mediated oxidation of LDL. Capsaicin repressed ROS generation, as well as subsequent mitochondrial membrane potential collapse, cytochrome c expression, chromosome condensation, and caspase-3 activation induced by oxLDL in HUVECs. Capsaicin also protected foam cell formation in macrophage RAW 264.7 cells. Our results suggest that capsaicin may prevent oxLDL-induced cellular dysfunction and protect RAW 264.7 cells from LDL oxidation. PMID:25603234

Chen, Kuo-Shuen; Chen, Pei-Ni; Hsieh, Yih-Shou; Lin, Chin-Yin; Lee, Yi-Hsun; Chu, Shu-Chen



Selective uptake of a toxic lipophilic anthracycline derivative by the low-density lipoprotein receptor pathway in cultured fibroblasts  

SciTech Connect

N-(N-Retinoyl)-L-leucyldoxorubicin 14-linoleate (r11-DOX), a new lipophilic derivative of doxorubicin, was synthesized and incorporated into low-density lipoprotein (LDL). The drug-LDL complex contained 100- 200 drug molecules/LDL particle. When cultured normal human fibroblasts were incubated with /sup 125/I-LDL-incorporated drug, there was a perfect correlation between the cellular uptake plus degradation of /sup 125/I-LDL and the cellular drug accumulation. The presence of excess native LDL inhibited the cellular uptake and degradation of /sup 125/I-LDL and the drug accumulation to the same extent. In contrast, methylated LDL, which does not bind to the LDL receptor, did not alter the cellular uptake and degradation of /sup 125/I-LDL nor did it alter the drug accumulation. When LDL receptor negative fibroblasts from a patient with the homozygous form of familial hypercholesterolemia were incubated with the drug-/sup 125/I-LDL complex, cellular drug accumulation was very low. The drug-LDL complex inhibited the growth of cultured normal human fibroblasts. The drug incorporated into methylated LDL was much less toxic. These findings suggest that r11-DOX incorporated into LDL is delivered to cells selectively by the LDL receptor pathway. This might be of value in the treatment of leukemia, since it has been previously found that leukemic cells exhibit higher LDL receptor activity than white blood cells and bone marrow cells from healthy subjects.

Vitols, S.G.; Masquelier, M.; Peterson, C.O.



Evidence that the lipid moiety of oxidized low density lipoprotein plays a role in its interaction with?macrophage?receptors  

PubMed Central

The binding of oxidatively damaged red blood cells (OxRBCs) to resident mouse peritoneal macrophages correlates with an increase in phosphatidylserine on the external leaflet of the plasma membrane. Liposomes rich in phosphatidylserine can inhibit this binding and also the binding of certain apoptotic cells. We have shown previously that oxidized low density lipoproteins (OxLDL) also can inhibit the binding of OxRBCs to resident mouse peritoneal macrophages. The present studies show that microemulsions prepared from the lipids extracted from OxLDL are very effective in inhibiting the binding of OxRBCs and also, to a lesser extent, of apoptotic thymocytes to macrophages. OxRBC binding was also inhibited by cholesterol phospholipid liposomes containing oxidized 1-stearoyl-2-linoleoyl-phosphatidylcholine. The binding and uptake of 125I-labeled OxLDL were also strongly inhibited by microemulsions of the lipids extracted from OxLDL and by cholesterol phospholipid liposomes containing oxidized 1-palmitoyl-2-arachidonoyl-phosphatidylcholine. Earlier studies have shown that the delipidated protein moiety of OxLDL can competitively inhibit macrophage binding of intact OxLDL, implicating the protein moiety as an effective receptor-binding domain of OxLDL with respect to some macrophage scavenger receptors. The present studies suggest that the lipid moiety of OxLDL may also play a role. PMID:9465098

Terpstra, Valeska; Bird, David A.; Steinberg, Daniel



Minimally modified low-density lipoprotein induces monocyte adhesion to endothelial connecting segment-1 by activating ?1 integrin  

PubMed Central

We have shown previously that treatment of human aortic endothelial cells (HAECs) with minimally modified low-density lipoprotein (MM-LDL) induces monocyte but not neutrophil binding. This monocyte binding was not mediated by endothelial E-selectin, P-selectin, vascular cell adhesion molecule-I, or intercellular adhesion molecule-I, suggesting an alternative monocyte-specific adhesion molecule. We now show that moncytic ?4?1 integrins mediate binding to MM-LDL-treated endothelial cells. We present data suggesting that the expression of the connecting segment-1 (CS-1) domain of fibronectin (FN) is induced on the apical surface of HAEC by MM-LDL and is the endothelial ?4?1 ligand in MM-LDL-treated cells. Although the levels of CS-1 mRNA and protein were not increased, we show that MM-LDL treatment causes deposition of FN on the apical surface by activation of ?1integrins, particularly those associated with ?5 integrins.Activation of ?1 by antibody 8A2 also induced CS-1-mediated monocyte binding. Confocal microscopy demonstrated the activated ?1 and CS-1colocalize in concentrated filamentous patches on the apical surface of HAEC. Both anti-CS-1 and an antibody to activated ?1 showed increased staining on the luminal endothelium of human coronary lesions with active monocyte entry. These results suggest the importance of these integrin ligand interactions in human atherosclerosis. J. Clin. Invest. 103:613–625 (1999) PMID:10074478

Shih, Peggy T.; Elices, Mariano J.; Fang, Zhuang T.; Ugarova, Tatiana P.; Strahl, Dana; Territo, Mary C.; Frank, Joy S.; Kovach, Nicholas L.; Cabanas, Carlos; Berliner, Judith A.; Vora, Devendra K.



LXR-SREBP-1c-Phospholipid Transfer Protein Axis Controls Very Low Density Lipoprotein (VLDL) Particle Size*  

PubMed Central

Liver X receptors (LXRs) activate triglyceride synthesis in liver directly and indirectly by inducing sterol regulatory element-binding protein-1c (SREBP-1c). When administered to wild-type mice, the LXR activator T0901317 produces a mild and transient hypertriglyceridemia. Here, we show that T0901317 produces massive hypertriglyceridemia when given to mice lacking low density lipoprotein (LDL) receptors (Ldlr?/? mice). Triglycerides ranged from 4000 to 6000 mg/dl, and the plasma turned milky. The median diameter of VLDL particles, measured by electron microscopy, increased from 43 to 112 nm, 87% exceeding 80 nm, the size of chylomicrons. Hypertriglyceridemia was prevented in Ldlr?/? recipient mice that lacked SREBP-1c (Ldlr?/?;Srebp-1c?/? double knock-out mice). In Ldlr?/? mice, T0901317 increased mRNAs not only for enzymes of fatty acid and triglyceride synthesis, but also for phospholipid transfer protein (PLTP), which transfers phospholipids into nascent VLDL, allowing particle expansion. The PLTP increase was blunted in Ldlr?/?;Srebp-1c?/? animals. When Ldlr?/?;Srebp-1c?/? mice received an adenovirus encoding Pltp, the hypertriglyceridemic response to T0901317 was partially restored and the VLDL size increased. We conclude that LXR agonists activate triglyceride synthesis and Pltp transcription by activating Srebp-1c. In concert with the increase in TG synthesis, the increased PLTP permits triglyceride incorporation into abnormally large VLDL, which are removed from plasma by LDL receptors. In the absence of LDL receptors, the large VLDLs accumulate and produce massive hypertriglyceridemia. PMID:20037162

Okazaki, Hiroaki; Goldstein, Joseph L.; Brown, Michael S.; Liang, Guosheng



Extracts of Ginkgo biloba L. leaves and Vaccinium myrtillus L. fruits prevent photo induced oxidation of low density lipoprotein cholesterol.  


Oxidation of low density lipoproteins (LDL) favours cholesterol loading in macrophages and formation of "foam cells", typical of the early atheroma lesions. LDL cholesterol oxidation generates oxysterols, extremely cytotoxic molecular species with diverse biological activities. Vegetable polyphenols are dietary components of pharmacological interest for their anti-oxidant properties. Ginkgo biloba L. (Gingkoaceae) leaves and Vaccinium myrtillus L. (Ericaceae) fruits are known for their beneficial effects in the treatment of various diseases involving free radicals and oxidative damage to biological lipids. In this study we investigated the effect of Ginkgo biloba L. and Vaccinium myrtillus L. extracts on the formation of cholesterol oxides during the photo induced oxidation of human LDL. The results demonstrate a concentration dependent inhibition of oxysterol formation in the presence of both extracts. Protection against oxidation was confirmed by the partial restoration of the normal electrophoretic mobility of LDL, which has been influenced by the UV irradiation. These effects extend knowledge of the therapeutic action of Ginkgo biloba L. and Vaccinium myrtillus L. as agents in anti-atherosclerotic regimens. PMID:23195191

Rasetti, M F; Caruso, D; Galli, G; Bosisio, E



Recognition of Porphyromonas gingivalis Gingipain Epitopes by Natural IgM Binding to Malondialdehyde Modified Low-Density Lipoprotein  

PubMed Central

Objective Increased risk for atherosclerosis is associated with infectious diseases including periodontitis. Natural IgM antibodies recognize pathogen-associated molecular patterns on bacteria, and oxidized lipid and protein epitopes on low-density lipoprotein (LDL) and apoptotic cells. We aimed to identify epitopes on periodontal pathogen Porphyromonas gingivalis recognized by natural IgM binding to malondialdehyde (MDA) modified LDL. Methods and Results Mouse monoclonal IgM (MDmAb) specific for MDA-LDL recognized epitopes on P. gingivalis on flow cytometry and chemiluminescence immunoassays. Immunization of C57BL/6 mice with P. gingivalis induced IgM, but not IgG, immune response to MDA-LDL and apoptotic cells. Immunization of LDLR?/? mice with P. gingivalis induced IgM, but not IgG, immune response to MDA-LDL and diminished aortic lipid deposition. On Western blot MDmAb bound to P. gingivalis fragments identified as arginine-specific gingipain (Rgp) by mass spectrometry. Recombinant domains of Rgp produced in E. coli were devoid of phosphocholine epitopes but contained epitopes recognized by MDmAb and human serum IgM. Serum IgM levels to P. gingivalis were associated with anti-MDA-LDL levels in humans. Conclusion Gingipain of P. gingivalis is recognized by natural IgM and shares molecular identity with epitopes on MDA-LDL. These findings suggest a role for natural antibodies in the pathogenesis of two related inflammatory diseases, atherosclerosis and periodontitis. PMID:22496875

Turunen, S. Pauliina; Kummu, Outi; Harila, Kirsi; Veneskoski, Marja; Soliymani, Rabah; Baumann, Marc; Pussinen, Pirkko J.; Hörkkö, Sohvi



Nanoscale Amphiphilic Macromolecules with Variable Lipophilicity and Stereochemistry Modulate Inhibition of Oxidized Low-Density Lipoprotein Uptake  

PubMed Central

Amphiphilic macromolecules (AMs) based on carbohydrate domains functionalized with poly(ethylene glycol) can inhibit the uptake of oxidized low density lipoprotein (oxLDL) and counteract foam cell formation, a key characteristic of early atherogenesis. To investigate the influence of lipophilicity and stereochemistry on the AMs' physicochemical and biological properties, mucic acid-based AMs bearing four aliphatic chains (2a) and tartaric acid-based AMs bearing two (2b and 2l) and four aliphatic chains (2g and 2k) were synthesized and evaluated. Solution aggregation studies suggested that both the number of hydrophobic arms and the length of the hydrophobic domain impact AM micelle sizes, whereas stereochemistry impacts micelle stability. 2l, the meso analogue of 2b, elicited the highest reported oxLDL uptake inhibition values (89%), highlighting the crucial effect of stereochemistry on biological properties. This study suggests that stereochemistry plays a critical role in modulating oxLDL uptake and must be considered when designing biomaterials for potential cardiovascular therapies. PMID:23795777

Poree, Dawanne E.; Zablocki, Kyle; Faig, Allison; Moghe, Prabhas V.; Uhrich, Kathryn E.



The Low Resolution Structure of ApoA1 in Spherical High Density Lipoprotein Revealed by Small Angle Neutron Scattering*  

PubMed Central

Spherical high density lipoprotein (sHDL), a key player in reverse cholesterol transport and the most abundant fo