bluuebunny/crossref_metadata_2025 huggingface dataset:
Esterified Cholesterol Accumulation Induced by Aggregated LDL Uptake in Human Vascular Smooth Muscle Cells Is Reduced by HMG-CoA Reductase Inhibitors
Authors: Llorente-Cortés Vicenta , Martínez-González José , Badimon Lina
Published: June 2011

Abstract
—Vascular smooth muscle cell (VSMC) proliferation is a key event in the development of atherosclerotic lesions. VSMCs synthesize extracellular matrix, where low density lipoproteins (LDLs) are trapped and become aggregated (agLDL). The objective of this study was to investigate the cholesterol uptake and accumulation triggered by agLDL in comparison with native LDL (nLDL) on unstimulated and platelet-derived growth factor–stimulated human aortic VSMCs and the role of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors on these processes. Esterified cholesterol (EC) accumulation induced by agLDL in VSMCs was correlated with the degree of aggregation and concentration. The EC content of VSMCs treated with 100 μg/mL of agLDL (80% aggregated) increased ≈70-fold over that in VSMCs incubated with the same concentration of nLDL. Whereas nLDL-derived EC was increased approximately twofold in platelet-derived growth factor–stimulated VSMCs, there was no effect of platelet-derived growth factor (10
−9
mol/L) on the uptake of agLDL. The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor simvastatin (5 μmol/L) reduced EC accumulation derived from agLDL uptake by 58% and 35% in platelet-derived growth factor—stimulated and unstimulated VSMCs, respectively. This inhibition was overcome by geranylgeraniol (10 μmol/L) and partially by farnesol (10 μmol/L). Fluorescence microscopy of the cellular internalization of agLDL labeled with the fluorochrome 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine demonstrated that simvastatin reduces EC accumulation derived from agLDL by inhibiting its endocytosis and that the effect is completely reversed by geranygeraniol. These results indicate that agLDLs are rapidly internalized by human VSMCs and that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors modulate EC accumulation. These data suggest a possible mechanism by which statins could contribute to the passivation and stabilization of actively growing atherosclerotic lesions.
Relationship Between Insulin Resistance and Partially Oxidized LDL Particles in Healthy, Nondiabetic Volunteers
Authors: Carantoni Marcello , Abbasi Fahim , Warmerdam Fabienne , Klebanov Mark , Wang Pei-Wen , Chen Yii-Der I. , Azhar Salman , Reaven Gerald M.
Published: June 2011

Abstract
—This study was performed in 36 healthy volunteers to define the relationship between plasma concentrations of partially oxidized low density lipoprotein (poxLDL), plasma glucose and insulin responses to oral glucose, and steady-state plasma glucose (SSPG) concentrations after a 180-minute infusion of somatostatin, insulin, and glucose. The concentration of poxLDL was estimated by determining the amount of conjugated dienes formed during in vitro LDL oxidation in the presence or absence of alanine. Under these conditions, the greater the in vitro antioxidant effect of alanine, the lower the amount of poxLDL that was present in plasma. The results demonstrated that plasma poxLDL concentration was significantly correlated with plasma glucose (
r
=.53,
P
<.001) and insulin (
r
=.43,
P
<.01) responses, SSPG concentrations (
r
=.53,
P
<.001), and plasma triglyceride (
r
=.42,
P
<.01) and HDL cholesterol (
r
=−.50,
P
<.002) concentrations. Furthermore, these relationships persisted when the data were corrected for differences in age, sex, body mass index, and the ratio of waist to hip girth. Of note, there was no correlation between poxLDL and LDL cholesterol concentration. When SSPG was entered along with age, sex, body mass index, and waist-to-hip ratio in a multiple regression model, SSPG alone was a significant prediction of poxLDL (
r
2
=.37,
P
<.02). The addition of plasma glucose and insulin responses and triglyceride and HDL cholesterol concentrations increased the
r
2
to only .47. These results show that the amount of poxLDL in plasma is significantly correlated with insulin resistance (ie, SSPG) and its metabolic consequences.
Plasma Viscosity and the Risk of Coronary Heart Disease
Authors: Koenig Wolfgang , Sund Malte , Filipiak Birgit , Döring Angela , Löwel Hannelore , Ernst Edzard
Published: June 2011

Abstract
—Plasma viscosity is determined by various macromolecules, eg, fibrinogen, immunoglobulins, and lipoproteins. It may therefore reflect several aspects involved in cardiovascular diseases, including the effects of classic risk factors, hemostatic disturbances, and inflammation. We examined the association of plasma viscosity with the incidence of a first major coronary heart disease event (CHD; fatal and nonfatal myocardial infarction and cardiac death; n=50) in 933 men aged 45 to 64 years of the MONICA project of Augsburg, Germany. The incidence rate was 7.23 per 1000 person-years (95% confidence interval [CI], 5.37 to 9.53), and the subjects were followed up for 8 years. All suspected cases of an incident CHD event were classified according to the MONICA protocol. There was a positive and statistically significant unadjusted relationship between plasma viscosity and the incidence of CHD. The relative risk of CHD events associated with a 1-SD increase in plasma viscosity (0.070 mPa · s) was 1.60 (95% CI, 1.25 to 2.03). After adjustment for age, total cholesterol, high density lipoprotein cholesterol, smoking, blood pressure, and body mass index, the relative risk was reduced only moderately (1.42; 95% CI, 1.09 to 1.86). The relative risk of CHD events for men in the highest quintile of the plasma viscosity distribution in comparison with the lowest quintile was 3.31 (95% CI, 1.19 to 9.25) after adjustment for the aforementioned variables. A large proportion of events (40%) occurred among men in the highest quintile. These findings suggest that plasma viscosity may have considerable potential to identify subjects at risk for CHD events.
Differences in the Metabolism of Postprandial Lipoproteins After a High-Monounsaturated-Fat Versus a High-Carbohydrate Diet in Patients With Type 1 Diabetes Mellitus
Authors: Georgopoulos Angeliki , Bantle John P. , Noutsou Marina , Swaim William R. , Parker Shirley J.
Published: June 2011

Abstract—There is little information comparing the effects of a high-monounsaturated (Mono)-fat versus a high-carbohydrate (CHO) diet in patients with type 1 diabetes mellitus. In the present study, the effects of these diets on a number of metabolic parameters were compared. Seventeen normolipidemic, nonobese patients with type 1 diabetes were provided with the diets for 4 weeks each in a randomized, crossover design. The percentages of Mono fat of the two diets were 25 Mono versus 9 CHO, with a corresponding total fat content of 40% versus 24% and a total CHO content of 45% versus 61%. At the end of each dietary period, parameters of glycemic control, coagulation factors, and fasting and postprandial lipoproteins were assessed. There were no differences in weight, glycemia, insulin dose, fasting lipid profile, or coagulation factors between the two diets. However, the metabolism of postprandial lipoproteins after a fat load differed; viz, after the Mono diet compared with the CHO diet, mean plasma triglyceride levels over 10 hours were higher (P=.0025, by repeated-measures ANOVA). The levels of triglyceride (P=.0045) and retinyl esters (P=.0046) in chylomicrons (Sf>400) and chylomicron remnants (Sf100 to 400) (P=.0047 andP=.043, respectively), and the total particle number (apolipoprotein B levels) in chylomicron remnants (P=.001) and small, very low density lipoprotein (Sf20 to 100,P=.016) were also higher. Our data suggest that in patients with type 1 diabetes, a CHO diet might be preferable to a Mono diet, since adherence to the former results in a lower number of circulating postprandial lipoprotein particles that are potentially atherogenic.
Effects of Atorvastatin on the Intracellular Stability and Secretion of Apolipoprotein B in HepG2 Cells
Authors: Mohammadi Abbas , Macri Joseph , Newton Roger , Romain Tanya , Dulay Daisy , Adeli Khosrow
Published: June 2011

Abstract
—We investigated the effects of atorvastatin, a new 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on the biogenesis of apolipoprotein B (apoB) in intact and permeabilized HepG2 cells. Intact cells were pretreated either with single or multiple doses of atorvastatin (0.1 to 20 μmol/L) for periods of 6 to 20 hours and pulsed with [
35
S]methionine. In some cases the cells were permeabilized with digitonin. Experiments were performed to investigate the effects of atorvastatin on (1) the rates of lipid synthesis and secretion, (2) the synthesis and accumulation of apoB, (3) the intracellular stability of apoB, (4) the amount of apoB-containing lipoprotein particles assembled in HepG2 microsomes, and (5) the secretion and accumulation of apoB into the culture medium. ApoB synthesis, degradation, and secretion were measured by pulse-chase experiments with [
35
S]methionine in both intact and permeabilized HepG2 cells. Lipid synthesis was assessed by pulse-labeling experiments with [
3
H]acetate or [
3
H]oleate bound to bovine serum albumin. Comparisons were made under basal conditions and in the presence of oleate (0.36 μmol/L). Atorvastatin acutely inhibited the synthesis of cholesterol and cholesterol ester but did not have a significant effect on triglyceride or phospholipid synthesis. Atorvastatin did not affect the uptake of [
35
S]methionine by the cells nor did it influence the synthesis of apoB or a control protein, albumin. However, atorvastatin reduced the secretion of apoB into the culture medium, apparently by enhancing the degradation of apoB in the cell under basal and induced conditions with oleate. The stability of apoB associated with the lipoprotein particles was also significantly lowered by atorvastatin. The stimulated degradation of apoB in atorvastatin-treated cells was sensitive to MG132, a proteasome inhibitor. The net effect of atorvastatin was a reduction in the number of apoB-containing lipoprotein particles of different sizes isolated from microsomes and a reduction in apoB secretion into the culture medium. The data suggest that atorvastatin may impair the translocation of apoB into the lumen of the endoplasmic reticulum, thus increasing the amount of apoB degraded intracellularly. It is hypothesized that atorvastatin alters these parameters primarily as a result of inhibiting cholesterol synthesis and limiting the availability of cholesterol and/or cholesterol ester for the normal assembly of apoB-containing lipoprotein particles.
Elevated Expression of Urokinase-like Plasminogen Activator and Plasminogen Activator Inhibitor Type 1 During the Vascular Remodeling Associated With Pulmonary Thromboembolism
Authors: Lang Irene M. , Moser Kenneth M. , Schleef Raymond R.
Published: June 2011

Abstract
—Information is lacking on the mechanisms involved in the organization, resolution, and repair of the vascular lumen after acute pulmonary thromboembolism. Because recent data suggest that the balance between plasminogen activators (PAs) and type 1 plasminogen activator inhibitor (PAI-1) plays a role in regulating cell migration within the extracellular matrix, we investigated the expression of these molecules by immunohistochemical and in situ hybridization analysis of pulmonary artery specimens from patients suffering fatal pulmonary embolism. The data were compared with the expression of these molecules in both patients’ noninvolved pulmonary arteries and organ donor pulmonary arteries. Regions of initial organization and vascular remodeling were identified by a modified trichrome stain and by the presence of proliferating cell nuclear antigen (PCNA), a cell marker of proliferation. Staining for tissue-type PA antigen was low to undetectable in endothelial cells directly in contact with the fibrin-platelet thromboembolus and in areas in which the endothelial cell lining was replaced by cell growth into the thrombus. Urokinase-like PA (u-PA) expression was detected in mononuclear cells within the thrombus in the initial phase of thromboembolism and within cells migrating into the thrombus during the later stages of organization. PAI-1 expression was elevated in the monolayer of endothelial cells underlying the fresh platelet-fibrin thromboembolus and in a PCNA-positive cell population present between the pulmonary arterial intima and the thromboembolus that represents early organization. Increased expression of PAI-1 may play a role in inhibiting proteolysis and fostering the localization of the acute fibrin-platelet thrombus to the vascular wall, which is followed by the upregulation of u-PA in migrating cells during the reorganization process.
Differential Expression of Functional Protease-Activated Receptor-2 (PAR-2) in Human Vascular Smooth Muscle Cells
Authors: Molino Marina , Raghunath P. N. , Kuo Alice , Ahuja Mena , Hoxie James A. , Brass Lawrence F. , Barnathan Elliot S.
Published: June 2011

Abstract
—The protease-activated family of G protein–coupled receptors includes PAR-1 and PAR-3, which are activated by thrombin, and PAR-2, which is activated by trypsin and tryptase. PAR-2 has recently been shown to be expressed in human endothelial cells. In the present studies, we have examined the expression of PAR-2 in other cells, particularly vascular smooth muscle, and tested whether the receptors are functional. The results show that PAR-2 is present in human aorta and coronary artery smooth muscle cells, as well as in arteries traversing the walls of the small intestine. It was also detected in human keratinocytes, sweat glands, intestinal smooth muscle, and intestinal epithelium, but not at all in myocardial smooth muscle and only inconsistently in intestinal veins and venules. Activation of aortic smooth muscle cells in culture with PAR-2 peptide agonists caused a transient increase in the cytosolic Ca
2+
concentration. In contrast, PAR-2 mRNA could not be detected in saphenous vein smooth muscle cells, and the same cells placed in culture showed little, if any, response to the PAR-2 agonist peptides. These observations show that PAR-2 is widely distributed in human vascular smooth muscle, particularly in arteries. However, this is not a universal finding and at least some venous smooth muscle cells, including those in saphenous veins, apparently do not express the receptor in detectable amounts.
No Effect of Consumption of Green and Black Tea on Plasma Lipid and Antioxidant Levels and on LDL Oxidation in Smokers
Authors: Princen Hans M. G. , van Duyvenvoorde Wim , Buytenhek Rien , Blonk Cor , Tijburg Lilian B. M. , Langius Jacqueline A. E. , Meinders A. Edo , Pijl Hanno
Published: June 2011

Abstract
—Intake of flavonoids is associated with a reduced cardiovascular risk. Oxidation of LDL is a major step in atherogenesis, and antioxidants may protect LDL from oxidation. Because tea is an important source of flavonoids, which are strong antioxidants, we have assessed in a randomized, placebo-controlled study the effect of consumption of black and green tea and of intake of isolated green tea polyphenols on LDL oxidation ex vivo and on plasma levels of antioxidants and lipids. Healthy male and female smokers (aged 34±12 years, 13 to 16 per group) consumed during a 4-week period 6 cups (900 mL) of black or green tea or water per day, or they received as a supplement 3.6 grams of green tea polyphenols per day (equivalent to the consumption of 18 cups of green tea per day). Consumption of black or green tea had no effect on plasma cholesterol and triglycerides, HDL and LDL cholesterol, plasma vitamins C and E, β-carotene, and uric acid. No differences were found in parameters of LDL oxidation. Intake of green tea polyphenols decreased plasma vitamin E significantly in that group compared with the control group (−11%
P
=.016) but had no effect on LDL oxidation ex vivo. We conclude that consumption of black or green tea (6 cups per day) has no effect on plasma lipids and no sparing effect on plasma antioxidant vitamins and that intake of a high dose of isolated green tea polyphenols decreases plasma vitamin E. Although tea polyphenols had a potent antioxidant activity on LDL oxidation in vitro, no effect was found on LDL oxidation ex vivo after consumption of green or black tea or intake of a green tea polyphenol isolate.
HDL3-Mediated Inhibition of Thrombin-Induced Platelet Aggregation and Fibrinogen Binding Occurs via Decreased Production of Phosphoinositide-Derived Second Messengers 1,2-Diacylglycerol and Inositol 1,4,5-tris-Phosphate
Authors: Nofer Jerzy-Roch , Walter Michael , Kehrel Beate , Wierwille Sonja , Tepel Martin , Seedorf Udo , Assmann Gerd
Published: June 2011

Abstract—We demonstrate that physiological concentrations of HDL3inhibit the thrombin-induced platelet fibrinogen binding and aggregation in a time- and concentration-dependent fashion. The underlying mechanism includes HDL3-mediated inhibition of phosphatidylinositol 4,5-bis-phosphate turnover, 1,2-diacylglycerol and inositol 1,4,5-tris-phosphate formation, and intracellular calcium mobilization. The inhibitory effects of HDL3on inositol 1,4,5-tris-phosphate formation and intracellular calcium mobilization were abolished after covalent modification of HDL3with dimethylsuberimidate. Furthermore, they could be blocked by calphostin C and bis-indolylmaleimide, 2 highly selective and structurally unrelated protein kinase C inhibitors. However, the inhibitory effects of HDL3were not blocked by H89, a protein kinase A inhibitor. In addition, HDL3failed to induce cAMP formation but stimulated the phosphorylation of the protein kinase C 40- to 47-kD major protein substrate. We observed a close temporal relationship between the HDL3-mediated inhibition of thrombin-induced inositol 1,4,5-tris-phosphate formation, intracellular calcium mobilization, and fibrinogen binding and the phosphorylation of the protein kinase C 40- to 47-kD major protein substrate. Taken together, these findings indicate that the HDL3-mediated inhibition of thrombin-induced fibrinogen binding and aggregation occurs via inhibition of phosphatidylinositol 4,5-bis-phosphate turnover and formation of 1,2-diacylglycerol and inositol 1,4,5-tris-phosphate. Protein kinase C may be involved in this process.
An Animal Model to Study Local Oxidation of LDL and Its Biological Effects in the Arterial Wall
Authors: Calara Federico , Dimayuga Paul , Niemann Audrey , Thyberg Johan , Diczfalusy Ulf , Witztum Joseph L. , Palinski Wulf , Shah Prediman K. , Cercek Bojan , Nilsson Jan , Regnström Jan
Published: June 2011

Abstract—Oxidized LDL (oxLDL) is present in atherosclerotic lesions and is believed to play a key role in atherogenesis. Mainly on the basis of cell culture studies, oxLDL has been shown to produce many biological effects that influence the atherosclerotic process. To study LDL oxidation in vivo, we have established a model in which Sprague-Dawley rats are given a single injection of unmodified human LDL (≥4 mg/kg body weight ). Within 6 hours, an accumulation of apolipoprotein B and epitopes present on oxLDL are detected in the arterial endothelium and media. The presence of oxLDL is associated with activation of the transcription factor nuclear factor-κB in the endothelium as well as endothelial expression of intercellular adhesion molecule-1. Injection of LDL enriched with the antioxidant probucol resulted in arterial accumulation of apolipoprotein B, but the expression of oxLDL-specific epitopes was reduced at 24 hours. Thus, this simple model has the potential to analyze the mechanisms behind and biological effects of LDL oxidation in vivo.
Role of Polymorphonuclear Leukocytes in Collar-Induced Intimal Thickening in the Rabbit Carotid Artery
Authors: Van Put Dominica J. M. , Van Osselaer Nancy , De Meyer Guido R. Y. , Andries Luc J. , Kockx Mark M. , De Clerck Luc S. , Bult Hidde
Published: June 2011

Abstract
—In this study, the involvement of polymorphonuclear leukocytes (PMNs) in the development of intimal thickening was investigated. A fibromuscular intima was induced by placing a silicone collar around the rabbit carotid artery for 3 days or 2 weeks; the contralateral artery was sham operated. Rabbits received placebo treatments (groups 1 and 3), granulocyte-colony stimulating factor (group 2; G-CSF, 20 μg · kg
−1
· d
−1
, delivered by subcutaneous osmotic pumps), or an anti-CD18 monoclonal antibody (group 4; 1.5 mg/kg IV). The G-CSF treatment raised the peripheral PMN count 5- to 12-fold but had no effect on intimal thickening on day 3, 12, or 14. A single injection of anti-CD18 prevented PMN extravasation 6 hours after collar implantation without influencing intimal hyperplasia on day 14. Repeated daily administration of anti-CD18 strongly bound to CD18 on peripheral PMNs and inhibited both PMN-dependent plasma extravasation in the skin and accumulation of CD14-immunoreactive leukocytes in the intima and media. However, anti-CD18 did not suppress early intimal thickening or accumulation of α-smooth muscle actin–immunoreactive cells by day 3. It thus appears that the PMN influx in the intima and media evoked by the perivascular collar is of little functional relevance to the subsequent smooth muscle cell migration and intimal thickening in this model.
Clinical Features Associated With the Homozygous Trp
64
Arg Mutation of the β3-Adrenergic Receptor
Authors: Sun Liming , Ishibashi Shun , Osuga Jun-ichi , Harada Kenji , Ohashi Ken , Gotoda Takanari , Fukuo Yoshihiro , Yazaki Yoshio , Yamada Nobuhiro
Published: June 2011

Abstract
—To characterize the clinical features associated with the Trp
64
Arg mutation of the β3-adrenergic receptor (β3-AR), the effects of this mutation, in particular the homozygous state (Arg/Arg), on obesity, blood pressure, and plasma lipoproteins were investigated in 2 populations: subjects residing on a small isolated island (group 1; n=746) and patients residing in Tokyo who attend a clinic for metabolic diseases (group 2; n=371). The allelic frequency of the Trp
64
Arg mutation was 23.4% in group 1 and 18.3% in group 2. No significant difference in the body mass index was observed between subjects with 3 different genotypes in each group. There was a trend that the Arg/Arg had higher systolic blood pressure than the Trp/Trp in both groups, but the differences were not statistically significant. The plasma LDL cholesterol levels were significantly lower in Arg/Arg than in Trp/Trp in men from the group 1 cohort (2.82±0.84 versus 3.19±0.7 mmol/L,
P
<0.05). These results suggest that the homozygous Trp
64
Arg mutation is not a major contributing factor for obesity, but potentially contributed to higher systolic blood pressure and low plasma levels of LDL cholesterol in Japanese men.
Two Major Loci Control Variation in β-Lipoprotein Cholesterol and Response to Dietary Fat and Cholesterol in Baboons
Authors: Rainwater David L. , Kammerer Candace M. , Hixson James E. , Carey K. D. , Rice Karen S. , Dyke Bennett , VandeBerg Jane F. , Slifer Susan H. , Atwood Larry D. , McGill Henry C. , VandeBerg John L.
Published: June 2011

Abstract
—We explored the genetic control of cholesterolemic responses to dietary cholesterol and fat in 575 pedigreed baboons. We measured cholesterol in β-lipoproteins (low density lipoprotein cholesterol [LDLC]) in blood drawn from baboons while they were consuming a baseline (low in cholesterol and fat) diet, a high–saturated fat (lard) diet, and a high-cholesterol, high–saturated fat diet. In addition to baseline levels (LDLC
Base
), we analyzed two variables for diet response: LDLC
RF
, which represents the LDLC response to increasing dietary fat (ie, high-fat diet minus baseline), and LDLC
RC
, which represents the LDLC response to increasing dietary cholesterol level (ie, high-cholesterol, high-fat diet minus high-fat diet). Heritabilities (
h
2
) of the 3 traits were 0.59 for LDLC
Base
, 0.14 for LDLC
RF
, and 0.59 for LDLC
RC
. In addition, LDLC
Base
and LDLC
RC
had a significant genetic correlation (ie, ρ
G
=0.54), suggesting that 1 or more genes exert pleiotropic effects on the 2 traits. Segregation analyses detected a single major locus that accounted for nearly all genetic variation in LDLC
RC
and some genetic variation in LDLC
Base
and LDLC
RF
and confirmed the presence of a different major locus that influences LDLC
Base
alone. Preliminary linkage analyses indicated that neither locus was linked to the LDL receptor gene, a likely candidate locus for LDLC. Detection of these major loci with large effects on the LDLC response to dietary cholesterol in a nonhuman primate offers hope of detecting and ultimately identifying similar loci that determine LDLC variation in human populations.
Potencies of Lipoproteins in Fasting and Postprandial Plasma to Accept Additional Cholesterol Molecules Released From Cell Membranes
Authors: Chung Byung Hong , Franklin Frank , Cho B. H. Simon , Segrest J. P. , Hart Karen , Darnell Betty E.
Published: June 2011

Abstract
—To investigate the role of various lipoproteins in plasma to promote cholesterol efflux from cell membranes, potencies of lipoproteins in normolipidemic fasting and postprandial (PP) plasmas to accept additional cholesterol molecules from cell membranes were determined. We used red blood cells (RBCs) and lipoproteins in fresh blood as donors and acceptors of cell membrane cholesterol, respectively. When fresh fasting plasma (n=24) containing active lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer proteins (CETP) was incubated with a 3-fold excess of autologous RBCs at 37°C for 18 hours, plasma cholesterol levels increased by 19.6% (38.5±14.2 mg/dL) owing to an exclusive increase in the CE level. Very low density lipoprotein (VLDL), low density lipoprotein (LDL), and high density lipoprotein (HDL) fractions retained 48.1%, 26.3%, and 25.6% of the net cholesterol mass increase in fasting plasma, resulting in 91%, 8%, and 21% increases in their cholesterol contents, respectively. The PP plasma was 1.3-fold more potent than fasting plasma in promoting cholesterol efflux from RBCs by associating excess cholesterol with chylomicrons, resulting in a 356% increase in the cholesterol content of chylomicrons. These increases in lipoprotein cholesterol content indicate that chylomicrons were about 3.9×, 44×, and 17× more potent than fasting VLDL, LDL, and HDL, respectively, in accepting additional cholesterol molecules released from RBCs. The capacity of PP plasma to promote cholesterol efflux from RBCs was significantly correlated with plasma cholesterol levels (
r
=0.60,
P
<0.005), triglycerides (
r
=0.68,
P
<0.001), chylomicrons (
r
=0.90,
P
<0.001), VLDL (
r
=0.65,
P
<0.001), and LDL (
r
=0.47,
P
<0.025) but not with the levels of HDL (
r
=−0.34,
P
<0.20). In fasting plasma containing a low level of VLDL and HDL, isolated chylomicrons supplemented to the plasma were ≈9× more potent than HDL in boosting the capacity of plasma to promote cholesterol efflux from RBCs. This study indicates that chylomicrons in PP plasma are the most potent ultimate acceptors of cholesterol released from cell membranes and that a low HDL level is not a factor that limits the ability of PP plasma to promote cholesterol efflux from cell membranes. Our data obtained from an in vitro system suggest that PP chylomicrons may play a major role in promoting reverse cholesterol transport in vivo, since the transfer of cholesterol from cell membranes to chylomicrons will lead to the rapid removal of this cholesterol by the liver. HDL in vivo may promote reverse cholesterol transport by enhancing the rapid removal of chylomicrons from the circulation, since the rate of clearance of chylomicrons is positively correlated with the HDL level in plasma.
Genetic Variation at the ApoA-IV Gene Locus and Response to Diet in Familial Hypercholesterolemia
Authors: Carmena-Ramon Rafael , Ascaso Juan F. , Real Jose T. , Ordovas Jose M. , Carmena Rafael
Published: June 2011

Abstract—Plasma lipid response to dietary fat and cholesterol is, in part, genetically controlled. The apolipoprotein A-IV (apoA-IV protein; APOA4, gene) has been shown to influence the response to dietary changes in normolipidemic individuals. The response to diet in subjects with familial hypercholesterolemia (FH) is also variable, and no studies are available on the influence of APOA4 mutations on dietary response in these subjects. We studied the effect of 2 common apoA-IV genetic variants (Gln360→His and Thr347→Ser) on the lipid response to the National Cholesterol Education Program type I (NCEP-I) diet in 67 FH heterozygotes (43 women and 24 men). Subjects were studied at baseline (after consuming for 1 month a diet with 35% fat [10% saturated] and 300 mg/d cholesterol) and after 3 months of consuming a low-fat diet. No sex-related differences were found, and results were combined for men and women. The APOA4-360 mutation was assessed in 67 subjects, 51 with genotype 1/1 and 16 with genotype 1/2. The APOA4-2 allele was associated with marginally significantly lower (P=0.049) low density lipoprotein (LDL) cholesterol levels and significantly lower (P=0.027) apoB levels independent of diet effects. After consuming an NCEP-I diet, carriers of the APOA4-2 allele showed a significantly lower reduction in apoB concentration (6.2%) than 1/1 subjects (14.1%;P=0.036); however, no significant differences in response were noted for LDL cholesterol. The APOA4-347 mutation was assessed in 63 individuals, 44 with the A/A allele and 19 with the A/T and T/T alleles. No significant differences were observed in baseline or post–NCEP-I diet values for these 2 groups in total, LDL, and high density lipoprotein cholesterol and plasma apoB levels. After dietary intervention, A/A individuals showed significant reductions in plasma triglyceride and very low density lipoprotein cholesterol levels; no changes were found in carriers of the T allele. Haplotype analysis suggested that in these FH subjects, the APOA4-360-2 allele was associated with lower plasma lipid levels during the NCEP-I diet period, whereas no significant effects were observed for the APOA4-347-T allele.
Differential Effects of Lovastatin on the Trafficking of Endogenous and Lipoprotein-Derived Cholesterol in Human Monocyte–Derived Macrophages
Authors: Cignarella Andrea , Brennhausen Beate , von Eckardstein Arnold , Assmann Gerd , Cullen Paul
Published: June 2011

Abstract
—Lovastatin has been shown to reduce cholesterol esterification in cholesterol-loaded human macrophages. Surprisingly, in nonloaded macrophages, lovastatin produces the opposite effect, lowering free cholesterol and increasing cholesteryl ester levels, as measured by high-performance liquid chromatography. In cholesterol-loaded cells, lovastatin reduced the cholesteryl esters of unsaturated but not those of saturated fatty acids. In nonloaded cells, by contrast, the cholesteryl esters of unsaturated fatty acids tended to increase after lovastatin treatment. Total (free plus esterified) cellular cholesterol content in nonloaded cells fell by 18% with 12-μmol/L lovastatin treatment but did not change in cholesterol-loaded cells. Lovastatin had no effect on the binding or uptake of acetylated low density lipoprotein, acyl coenzyme A:cholesterol acyltransferase (ACAT) activity, the secretion of [
3
H]cholesterol into the medium, or lysosomal hydrolysis of cholesteryl esters. Apolipoprotein (apo) E mRNA levels increased but apoE secretion into the medium decreased with lovastatin treatment in both cholesterol-loaded and nonloaded cells. Cholesterol of exogenous origin has been shown to pass via the cell membrane before its esterification by ACAT. We postulate that this is not the case for endogenous cholesterol, which may have direct access to ACAT. Our findings therefore suggest that lovastatin hinders the delivery of intracellular cholesterol to the plasma membrane, resulting in increased free cholesterol and lower levels of cholesteryl ester in cholesterol-loaded cells. In nonloaded cells, virtually all cholesterol is of endogenous origin and is normally translocated to the cell membrane. Lovastatin prevents this process, thus shunting newly synthesized cholesterol toward esterification and leading to an increase in the concentration of cholesteryl esters, even in the face of a drop in total and free cholesterol levels. Intracellular apoE may play a role in this process.
A Truncated Species of Apolipoprotein B (B-38.7) in a Patient With Homozygous Hypobetalipoproteinemia Associated With Diabetes Mellitus
Authors: Ohashi Ken , Ishibashi Shun , Yamamoto Michiyo , Osuga Jun-ichi , Yazaki Yoshio , Yukawa Susumu , Yamada Nobuhiro
Published: June 2011

Abstract
—Familial hypobetalipoproteinemia is caused by mutations in the apolipoprotein (apo) B gene. We identified a 57-year-old woman whose plasma total cholesterol and apoB levels were 2.17 mmol/L and 0.03 g/L, respectively. Separation of plasma lipoproteins by sodium dodecyl sulfate–polyacrylamide gel electrophoresis revealed the absence of apoB-100 and the presence of a faster-migrating form of apoB with an apparent
M
r
of 195 kDa. Direct sequencing of a polymerase chain reaction–amplified fragment of the patient’s apoB gene DNA revealed a single C→T transition at nucleotide 5472 that converts glutamine 1755 (CAA) to a stop codon (TAA). We predict this novel nonsense mutation of the apoB gene to produce a truncated protein that contains 1754 amino-terminal amino acid residues of apoB-100. We designated this mutant form of apoB apoB-38.7 by following the centile nomenclature of the apoB species. The same mutation was found in both of her children. The proband revealed clinical findings of retinitis pigmentosa, acanthocytosis, and loss of deep tendon reflexes that are characteristic of severe hypobetalipoproteinemia. In addition, the proband had type II diabetes mellitus with nephropathy, anemia, cholelithiasis, hepatic hemangioma, bronchiectasis, and extensive calcification of major arteries including, the celiac, splenic, and renal. In summary, we have found a novel truncated apoB, apoB-38.7, in a patient with an unusual presentation of hypobetalipoproteinemia that includes diabetes mellitus and extensive arterial calcification.
Insulin and 2-Hour Glucose Levels Are Inversely Related to Lp(a) Concentrations Controlled for
LPA
Genotype
Authors: Rainwater David L. , Haffner Steven M.
Published: June 2011

Abstract
—In this study we assessed the relationship of lipoprotein(a) [Lp(a)] with diabetes status and with measures of glucose and insulin in a population of Mexican Americans having a high prevalence of non–insulin-dependent diabetes mellitus (NIDDM). Because of enormous allelic diversity at
LPA
[the locus encoding the apo(a) protein] that directly influences Lp(a) concentrations, it was first necessary to adjust for the large effects of variation at
LPA
. We calculated residual Lp(a) concentration as the difference between observed and expected; expected Lp(a) concentration was based on information from all family members sharing each identical-by-descent (IBD) allele. We found significant effects of sex and age on residual Lp(a) concentrations that increased with age (
P
=0.0004) and in females (
P
=0.0034). Although diabetes status per se was not related to residual Lp(a) concentrations (
P
=0.097), we found that residual Lp(a) concentrations were inversely correlated with fasting insulin (
P
=0.0017) and with insulin (
P
=0.0028) and glucose (
P
=0.0429) concentrations measured 2 hours after a glucose challenge. Furthermore, significant inverse correlations with the 2 insulin measures were observed for a subgroup of nondiabetic individuals. Inclusion of 2 lipid measures (plasma concentrations of cholesterol and triglycerides) in the models showed that the correlations with insulin and glucose were independent of the relationship between Lp(a) concentrations and the lipid measures. Also, we determined the residual size for each apo(a) isoform by adjusting for the IBD isoform group average. Although not related to diabetes status, residual apo(a) isoform size was positively correlated with fasting insulin (
P
=0.0013) and with 2-hour glucose (
P
=0.0246) and 2-hour insulin (
P
=0.0182) concentrations. In addition, significant correlations for all 4 measures were found for the subgroup of nondiabetic individuals. Thus, the results demonstrate that glucose-intolerant individuals have significantly lower residual Lp(a) concentrations and a significant increase of residual apo(a) size.
Warfarin Causes Rapid Calcification of the Elastic Lamellae in Rat Arteries and Heart Valves
Authors: Price Paul A. , Faus Samuel A. , Williamson Matthew K.
Published: June 2011

Abstract—High doses of warfarin cause focal calcification of the elastic lamellae in the media of major arteries and in aortic heart valves in the rat. Aortic calcification was first seen after 2 weeks of warfarin treatment and progressively increased in density at 3, 4, and 5 weeks of treatment. By 5 weeks, the highly focal calcification of major arteries could be seen on radiographs and by visual inspection of the artery. The calcification of arteries induced by warfarin is similar to that seen in the matrix Gla protein (MGP)–deficient mouse, which suggests that warfarin induces artery calcification by inhibiting γ-carboxylation of MGP and thereby inactivating the putative calcification-inhibitory activity of the protein. Warfarin treatment markedly increased the levels of MGP mRNA and protein in calcifying arteries and decreased the level of MGP in serum. Warfarin treatment did not affect bone growth, overall weight gain, or serum calcium and phosphorus levels, and, because of the concurrent administration of vitamin K, prothrombin times and hematocrits were normal. The results indicate that the improved warfarin plus vitamin K treatment protocol developed in this study should provide a useful model to investigate the role of MGP in preventing calcification of arteries and heart valves.
Low-Cholesterol and High-Fat Diets Reduce Atherosclerotic Lesion Development in ApoE-Knockout Mice
Authors: Calleja Lucía , París Miguel A. , Paul Antoni , Vilella Elisabet , Joven Jorge , Jiménez Antonio , Beltrán Gabriel , Uceda Marino , Maeda Nobuyo , Osada Jesús
Published: June 2011

Abstract
—We have investigated the effect of most common oils used in human nutrition on the development of atherosclerosis in apoE-knockout mice. Seven groups of animals, separated according to sex, were fed for 10 weeks either chow diet or the chow diet 10% (wt/wt) enriched with different oils (palm, coconut, 2 types of olive oil, and 2 types of sunflower oil) without addition of cholesterol. At the end of this period, plasma lipid parameters were measured and vascular lesions scored. None of the diets induced changes in plasma cholesterol concentrations, whereas plasma triglycerides were uniformly reduced in all diet groups. Some diets caused significant reductions in the size of atherosclerotic lesions in males and others in females; males responded most to sunflower oils and females to palm oil and one olive oil (II). The lesion reduction in males consuming sunflower oils was associated with the decrease of triglycerides in triglyceride-rich lipoproteins, whereas the decrease in females consuming olive oil II or palm oil was accompanied by an increase in plasma apoA-I. The increase in plasma apoA-I in the latter condition, is mainly due to overexpression of hepatic message elicited by a mechanism independent of apoE ligand. The data suggest that the different diets modulate lesion development in a gender specific manner and by different mechanisms and that the development of atherosclerosis, due to genetic deficiencies, may be modulated by nutritional maneuvers that may be implemented in human nutrition.
Evidence That Lipoproteins Are Carriers of Bioactive Factors
Authors: Sachinidis Agapios , Kettenhofen Ralf , Seewald Stefan , Gouni-Berthold Ioanna , Schmitz Udo , Seul Claudia , Ko Yon , Vetter Hans
Published: June 2011

Abstract
—We recently demonstrated that the mitogenic effect of LDL (100 μg/mL) as well as its early intracellular signaling pathway are mediated by a pertussis-toxin (PTX)-sensitive G
i
protein-coupled receptor that is independent from its classical receptor and involves activation of extracellular response kinases (ERK1/2) (also known as p44
mapk
/p42
mapk
). In the present study we examined whether LDL-adherent factors may be responsible for some of the effects of LDL. The term “signaling activity” is used to characterize fractions that cause an increase in intracellular free Ca
2+
concentration or stimulate ERK1/2 and c-fos mRNA expression. LDL, HDL, and VLDL stimulate ERK1/2 with the following order of potency: LDL>HDL>VLDL. After delipidation of LDL with chloroform/methanol/water mixtures a PTX-sensitive signaling activity was found in one fraction arbitrarily called LDL-F. After further analysis of LDL-F compounds by high pressure liquid chromatography, a PTX-sensitive signaling activity was detected only in the fraction with a retention time of 33 minutes (arbitrarily called LDL-F33). Similarly, after separation of sphingosine-1–phosphate (SPP) and sphingosylphosphorylcholine (SPC) by high pressure liquid chromatography, a PTX-sensitive signaling activity was found in the fractions 33 and 33 to 35, respectively. These findings demonstrate that the effects of LDL-F33 are mimicked by similar fractions collected from SPP/SPC, hence suggesting that these LDL-adherent molecules are possibly closely related to SPP/SPC. A PTX-sensitive signaling activity was also detected in HDL and HDL-F33. Therefore, LDL and other lipoproteins may function as carriers for bioactive phospholipids thereby contributing to the development of coronary artery disease. Our findings support a new research concept that may contribute in elucidating cellular mechanisms promoting coronary artery disease.
Pleiotropic Genetic Effects on LDL Size, Plasma Triglyceride, and HDL Cholesterol in Families
Authors: Edwards Karen L. , Mahaney Michael C. , Motulsky Arno G. , Austin Melissa A.
Published: June 2011

Abstract
—The interrelationships among low density lipoprotein (LDL) particle size, plasma triglyceride (TG), and high density lipoprotein cholesterol (HDL-C) are well established and may involve underlying genetic influences. This study evaluated common genetic effects on LDL size, TG, and HDL-C by using data from 85 kindreds participating in the Genetic Epidemiology of Hypertriglyceridemia (GET) Study. A multivariate, maximum likelihood–based approach to quantitative genetic analysis was used to estimate the additive effects of shared genes and shared, unmeasured nongenetic factors on variation in LDL size and in plasma levels of TG and HDL-C. A significant (
P
<0.001) proportion of the variance in each trait was attributable to the additive effects of genes. Maximum-likelihood estimates of heritability were 0.34 for LDL size, 0.41 for TG, and 0.54 for HDL-C. Significant (
P
<0.001) additive genetic correlations (
ρ
G
), indicative of the shared additive effects of genes on pairs of traits, were estimated between all 3 trait pairs: for LDL size and TG
ρ
G
=−0.87, for LDL size and HDL-C
ρ
G
=0.65, and for HDL-C and TG
ρ
G
=−0.54. A similar pattern of significant environmental correlations between the 3 trait pairs was also observed. These results suggest that a large proportion of the well-documented correlations in LDL size, TG, and HDL-C are likely attributable to the influence of the same gene(s) in these families. That is, the gene(s) that may contribute to decreases in LDL size also contribute significantly to higher plasma levels of TG and lower plasma levels of HDL-C. These relationships may be useful in identifying genes responsible for the associations between these phenotypes and susceptibility to cardiovascular disease in these families.
Intravenous and Oral Antithrombotic Efficacy of the Novel Platelet GPIIb/IIIa Antagonist Roxifiban (DMP754) and Its Free Acid Form, XV459
Authors: Mousa Shaker A. , Kapil Ram , Mu Dun-Xu
Published: June 2011

Abstract
—Currently used antiplatelet drugs, including aspirin, ticlopidine, and others, are effective against certain but not all of the many endogenous platelet activators. Because of their limited efficacy, a significant number of serious thromboembolic complications still occur, highlighting the need for a more effective therapy. DMP754 (roxifiban), a prodrug of XV459, is a recently discovered, potent antiplatelet agent with high affinity and specificity for platelet GPIIb/IIIa receptors that blocks platelet aggregate formation regardless of the agonist (IC
50
=0.030 to 0.05 μmol/L) or anticoagulant used for blood collection. DMP754 rapidly converts to its active free-acid form, XV459, which has a comparable high affinity for both resting and activated platelets (
K
d
=1 to 2 nmol/L) and a relatively slow rate of dissociation from resting platelets. The present study was undertaken to determine intravenous and oral antithrombotic efficacies of DMP754 and XV459 and to compare them with those of other antiplatelet and anticoagulant agents in canine models of arterial thrombosis. In these models, thrombosis was induced either electrolytically (200-μA anodal current) in the carotid artery or mechanically by external clamping of the femoral artery along with stenosis, which resulted in either total occlusive thrombus formation or cyclic flow reduction, respectively. DMP754 and XV459 were given either intravenously (0.1 mg/kg bolus) or orally (0.1 to 0.4 mg/kg). Additionally, the antithrombotic efficacies of DMP754, aspirin, heparin, and ticlopidine in the canine carotid artery electrolytic injury model were compared. DMP754 demonstrated oral bioavailability of 20.8% in dogs after administration at different doses and prevented cyclic flow reduction (ED
90–100
=<0.1 mg/kg IV or PO). Additionally, both DMP754 and XV459 (0.1 mg/kg IV or 0.3 to 0.4 mg/kg PO) demonstrated maximal antithrombotic efficacy in preventing electrically induced carotid and coronary artery thrombosis and significant antithrombotic efficacy (
P
<0.001) at relatively low doses in different settings of arterial thrombosis in the canine model. DMP754 resulted in a significant reduction in thrombus mass and sustained arterial blood flow with 100% prevention of occlusive and nonocclusive thrombosis. In contrast, administration of aspirin (10 mg/kg PO for 2 days), heparin (10 IU/kg IV bolus followed by 90 IU/kg IV infusion over 3 hours), or ticlopidine (300 mg/kg PO for 3 days) before initiation of arterial thrombosis did not reduce the incidence of electrolytic injury–induced occlusive arterial thrombosis. These studies demonstrated a distinct antithrombotic efficacy of DMP754 as compared with existing strategies and suggest potential intravenous and oral antithrombotic uses of DMP754 in the prevention and treatment of thromboembolic disorders.