bluuebunny/crossref_metadata_2025 huggingface dataset:
ApoB-100 Secretion by HepG2 Cells Is Regulated by the Rate of Triglyceride Biosynthesis but Not by Intracellular Lipid Pools
Authors: Benoist Fabienne , Grand-Perret Thierry
Published: June 2011

Triglycerides (TGs), cholesteryl esters (CEs), cholesterol, and phosphatidylcholine have been independently proposed as playing regulatory roles in apoB-100 secretion; the results depended on the cellular model used. In this study, we reinvestigate the role of lipids in apoB-100 production in HepG2 cells and in particular, we clarify the respective roles of intracellular mass and the biosynthesis of lipids in the regulation of apoB-100 production. In a first set of experiments, the pool size of cholesterol, CEs, and TGs was modulated by a 3-day treatment with either lipid precursors or inhibitors of enzymes involved in lipid synthesis. We used simvastatin (a hydroxymethylglutaryl coenzyme A reductase inhibitor), 58-035 (an acyl coenzyme A cholesterol acyltransferase inhibitor), 5-tetradecyloxy-2-furancarboxylic acid (TOFA, an inhibitor of fatty acid synthesis), and oleic acid. The secretion rate of apoB-100 was not affected by the large modulation of lipid mass induced by these various pretreatments. In a second set of experiments, the same lipid modulators were added during a 4-hour labeling period. Simvastatin and 58-035 inhibited cholesterol and CE synthesis without affecting apoB-100 secretion. By contrast, treatment of HepG2 cells with TOFA resulted in the inhibition of TG synthesis and apoB-100 secretion. This effect was highly specific for apoB-100 and was reversed by adding oleic acid, which stimulated both TG synthesis and apoB-100 secretion. Moreover, a combination of oleic acid and 58-035 inhibited CE biosynthesis and increased both TG synthesis and apoB-100 secretion. These results show that in HepG2 cells TG biosynthesis regulates apoB-100 secretion, whereas the rate of cholesterol or CE biosynthesis has no effect.
Apolipoprotein E Alleles and Risk of Coronary Disease
Authors: Wilson Peter W.F. , Schaefer Ernst J. , Larson Martin G. , Ordovas Jose M.
Published: June 2011

A meta-analysis was undertaken to assess the impact of apolipoprotein E (apo E) alleles (ε2, ε3, and ε4) on coronary disease in 14 published observational studies (9 clinical coronary disease and 5 coronary angiography). In comparison with ε3, the ε4 allele was associated with greater odds for coronary heart disease, and summary estimates of the odds ratios (ORs) and (95% confidence intervals) for both sexes combined were OR=0.98 (0.85-1.14) for ε2 and OR=1.26 (1.13-1.41) for ε4. Separate analyses for men and women showed similar associations. In angiographic studies the relative odds for significant coronary artery disease among both sexes combined was OR=0.76 (0.55-1.05) for ε2 and OR=1.11 (0.88-1.40) for ε4. The overall impression is that ε4 is associated with clinical and coronary disease and that results are similar in men and women.
The Role of Plasminogen, Plasminogen Activators, and Matrix Metalloproteinases in Primate Arterial Smooth Muscle Cell Migration
Authors: Kenagy R.D. , Vergel S. , Mattsson E. , Bendeck M. , Reidy M.A. , Clowes A.W.
Published: June 2011

The migration of arterial smooth muscle cells (SMCs) plays an important role in normal vessel development as well as the pathobiology of blood vessels. Because it is difficult to study cell migration in primates, we used ex vivo explants. The response of baboon aortic medial explants incubated in vitro in a serum-free medium with insulin and transferrin was compared with the response of whole artery injured in vivo by a balloon catheter to establish the validity of the explant model. Both the time course of entry of SMCs into the S phase and the changes in matrix metalloproteinase 9 were similar in the artery and the explants. SMCs began migrating from explants after a lag of 3 days. By day 11, >90% of the explants exhibited SMC migration from the tissue (percent of explants with ≥1 migrating cell). Basal migration was inhibited by antibodies to urokinase and tissue-type plasminogen activator, whereas addition of plasminogen to the explants increased migration. An inhibitor of matrix metalloproteinases, BB-94 (Batimistat), decreased migration, as did α2-macroglobulin. These data demonstrate that proteinases of the matrix metalloproteinase and plasminogen/plasminogen activator families play an important role in the migration of primate arterial SMCs through the extracellular matrix.
The Association of Hyperestrogenemia With Coronary Thrombosis in Men
Authors: Phillips Gerald B. , Pinkernell Bruce H. , Jing Tian-Yi
Published: June 2011

Both hyperestrogenemia and hypotestosteronemia have been reported in association with myocardial infarction (MI) in men. It was previously observed that the serum testosterone concentration correlated negatively with the degree of coronary artery disease (CAD) in men who had never had a known MI. The present study investigated the relationship of sex hormone levels to the thrombotic component of MI by comparing these levels in 18 men who had had an MI (ie, thrombosis) and 50 men with no history of MI (ie, no thrombosis) whose degree of CAD was in the same range. The mean degree of CAD, age, and body mass index in these two groups was not significantly different. The mean serum estradiol level in the men who had had an MI (38.5±8.8 pg/mL) was higher (
P
=.002) than the level in the men who had not had an MI (31.9±7.1 pg/mL). The mean levels of testosterone, free testosterone, sex hormone–binding globulin, insulin, dehydroepiandrosterone sulfate, cholesterol, HDL cholesterol, and systolic and diastolic blood pressure did not differ significantly. Estradiol was the only variable measured that showed a significant relationship to MI (
P
<.003 by multivariate logistic regression). These findings suggest that hyperestrogenemia may be related to the thrombosis of MI.
Ultrasonographically Assessed Maximum Carotid Artery Wall Thickness in Mexico City Residents and Mexican Americans Living in San Antonio, Texas
Authors: Wei Ming , Gonzalez Clicerio , Haffner Steven M. , O'Leary Daniel H. , Stern Michael P.
Published: June 2011

Measurements of carotid artery wall thickness are often used as a surrogate for atherosclerosis. However, few studies have performed these measurements in populations of Mexican origin. Since Mexicans in Mexico City consume high-carbohydrate diets and have carbohydrate-induced dyslipidemia (high triglyceride and low HDL cholesterol levels) compared with Mexican Americans living in San Antonio, Tex, we questioned whether they also had more atherosclerosis than San Antonio Mexican Americans. Mean maximum intimal-medial thickness (IMT) of the common (CCA) and internal (ICA) carotid arteries were measured in 867 subjects aged 35 to 64 years (40% men) in two Mexican-origin populations, one from San Antonio (n=202) and the other from Mexico City (n=665). IMTs in the two cities were compared, and their associations with cardiovascular risk factors were analyzed. Older age, male sex, high levels of total cholesterol, low levels of HDL cholesterol, and high systolic blood pressure were positively associated with both CCA IMT and ICA IMT. Cigarette smoking was significantly associated with ICA IMT. CCA and ICA IMTs in diabetic subjects were thicker than in nondiabetic subjects in both men and women (all
P
<=.05). CCA IMT was thicker in the San Antonio than the Mexico City subjects after adjustment for cardiovascular risk factors (0.81 versus 0.76 mm in men and 0.77 versus 0.71 mm in women;
P
<.001 for city difference). San Antonio men also had thicker ICA IMT than their counterparts in Mexico City (0.88 versus 0.83 mm), but the reverse was true for women (0.73 versus 0.77 mm; interaction between sex and city,
P
<.05). Our results indicate that men had higher carotid IMTs than women. CCA IMT was thicker in San Antonio Mexican Americans than in Mexico City residents. The differences in ICA IMTs between San Antonio and Mexico City were inconsistent. Thus, since Mexico City residents consume high-carbohydrate diets, the data do not support an atherogenic effect of such diets. The interaction between sex and city on ICA IMT deserves further study.
Transgenic Rabbits Expressing Human Apolipoprotein A-I in the Liver
Authors: Duverger Nicolas , Viglietta Céline , Berthou Laurence , Emmanuel Florence , Tailleux Anne , Parmentier-Nihoul Laurence , Laine Bernard , Fievet Catherine , Castro Graciela , Fruchart Jean Charles , Houbebine Louis Marie , Denèfle Patrice
Published: June 2011

Human apolipoprotein A-I (apo A-I) transgenic rabbits were created by use of an 11-kb genomic human apo A-I construct containing a liver-specific promoter. Five independent transgenic lines were obtained in which human apo A-I gene had integrated and was expressed. Plasma levels of human apo A-I ranged from 8 to 100 mg/dL for the founder and up to 175 mg/dL for the progeny. Rabbit apo A-I levels were substantially decreased in the transgenic rabbits. HDL cholesterol (HDL-C) levels were higher in two of the five transgenic rabbit lines than in controls (line 20 versus nontransgenic littermate, HDL-C=80±7 versus 37±6 mg/dL; line 8 versus nontransgenic littermate, HDL-C=54±16 versus 35±6 mg/dL). This resulted in less atherogenic lipoprotein profiles, with very low (VLDL+LDL-C)/HDL-C ratios. HDL size and protein and lipid compositions were similar between transgenic and littermate nontransgenic rabbits. However, a large amount of pre-β apo A-I–containing lipoproteins was observed in the plasma of the highest human apo A-I expressor. Cell cholesterol efflux was evaluated with the incubation of whole serum from transgenic and control rabbits. Cell cholesterol efflux was highly correlated with HDL cholesterol, with apo A-I, and with the presence of pre-β apo A-I–containing lipoproteins. These rabbits will be an extremely useful model for the evaluation of the effect of increased hepatic apo A-I expression on atherosclerosis.
Esterified Estrogens With and Without Methyltestosterone Decrease Arterial LDL Metabolism in Cynomolgus Monkeys
Authors: Wagner Janice D. , Zhang Li , Williams J. Koudy , Register Thomas C. , Ackerman Dennis M. , Wiita Brinda , Clarkson Thomas B. , Adams Michael R.
Published: June 2011

Although both epidemiological and experimental evidence suggests that estrogen replacement therapy reduces the risk of coronary heart disease, the mechanisms for this beneficial effect are largely unknown. Furthermore, the addition of progestins or androgens to estrogen replacement therapy is of concern. The objective of this study was to examine the effects of esterified estrogens alone or in combination with an androgen on arterial LDL metabolism and early atherogenesis in ovariectomized female cynomolgus monkeys. Arterial LDL metabolism was assessed by using dual-labeled LDL that was injected 24 hours before necropsy. Arterial LDL degradation was reduced by 64% to 84% and cholesteryl ester content was decreased by ≈50% in the thoracic aorta in both treatment groups compared with controls. In addition, aortic lipid peroxidation products, as assessed by thiobarbituric acid reaction, were significantly lower in animals treated with esterified estrogens, with a similar trend for combined estrogen-androgen treatment. Both treatments also reduced plasma concentrations of apoB-containing lipoproteins, reduced LDL particle size, and increased total-body LDL catabolism. The combination of decreased arterial LDL metabolism, decreased arterial lipid peroxidation, and improved plasma lipoprotein metabolism may explain some of the protective effects of estrogens on coronary heart disease and indicate that beneficial actions extend to a combination of estrogen and androgen.
LDL Stimulates Chemotaxis of Human Monocytes Through a Cyclooxygenase-Dependent Pathway
Authors: Kreuzer Jörg , Denger Stefanie , Jahn Lothar , Bader Jörg , Ritter Kai , von Hodenberg Eberhard , Kübler Wolfgang
Published: June 2011

Monocyte migration into the vessel wall is an early step in atherogenesis. Even though a number of chemotactic factors have been identified, the regulation of the chemotactic response is not clearly understood. As the release of arachidonic acid has been implicated in monocyte chemotaxis, we studied the influence of LDL, which can supply this fatty acid to cells, on the chemotactic mobility of monocytes. Migration of human monocytic U937 cells was abolished by a 30-hour incubation in medium containing lipoprotein-depleted 10% fetal calf serum. Thereafter, human VLDL, LDL, acetyl LDL, methyl LDL, HDL, free cholesterol, linoleic acid, oleic acid, or arachidonic acid was added. At the end of varying incubation periods (0.5 to 8 hours), chemotaxis, viability, and cellular cholesterol content were measured. In the same experimental setting we also studied the effects of the pharmacological agents chloroquine, indomethacin, and acetylsalicylic acid on LDL-mediated chemotaxis. Chemotaxis was restored by LDL in a dose- and time-dependent manner starting at concentrations as low as 5 μg/mL and at incubations as brief as 30 minutes. The other lipoproteins tested (VLDL, HDL, acetyl LDL, and methyl LDL) as well as free cholesterol had no comparable effect on chemotaxis. Viability and total cholesterol content did not differ among the groups. Simultaneous incubation of cells with chloroquine, indomethacin, and acetylsalicylic acid reduced restitution of chemotaxis by LDL by 71%, 82%, and 68%, respectively. In contrast, the agents had only slight inhibitory effects on the chemotactic mobility of serum-fed control cells. Incubation with linoleic acid showed a 60% restoration of chemotaxis, whereas arachidonic acid stimulated chemotaxis by 140% compared with the positive control. Preincubation of LDL with the monoclonal antibody MB47 directed against LDL resulted in a significantly reduced migratory response. The data suggest a novel cyclooxygenase-dependent regulatory mechanism of chemotaxis by LDL.
Effects of Diet and Exercise on Qualitative and Quantitative Measures of LDL and Its Susceptibility to Oxidation
Authors: Beard Christopher M. , Barnard R. James , Robbins David C. , Ordovas Jose M. , Schaefer Ernst J.
Published: June 2011

Abstract
The purpose of this study was to investigate the effects of an intensive diet and exercise program on the quantity and quality of LDL as well as its susceptibility to in vitro oxidation. The diet was low in fat (<10% kcal) and cholesterol (<100 mg/d), while high in complex, unrefined carbohydrates (>70% kcal) and fiber (35 g/1000 kcal). The study was composed of 80 participants in a 3-week residential program where food was provided ad libitum and there was daily aerobic exercise, primarily walking. In each subject, preparticipation and postparticipation fasting blood samples were drawn and LDL was isolated via density gradient ultracentrifugation. LDL particle diameter was determined by gradient gel electrophoresis of serum (n=23). Isolated LDL was either separated into 6 subfractions by saline gradient equilibrium ultracentrifugation (n=26) or subjected to in vitro copper oxidation (n=32). Significant reductions (
P
<.01) in serum levels of cholesterol (20%), LDL-cholesterol (20%), HDL-cholesterol (17%), triglycerides (26%), and glucose (16%) as well as in body weight (4%) were noted for the total population. The mean particle diameter of the LDL increased (24.2±0.2 to 25.1±0.14 nm,
P
<.01) and was correlated with the reduction in serum triglycerides (
r
=.58,
P
<.01). Six of 22 subjects changed in LDL phenotype from B (≤25.5 nm) to A (>25.5 nm). The percentage of LDL-cholesterol carried in the more dense subfractions fell significantly, while that carried by the less dense fractions increased. Initial oxidation levels fell (21%), while the lag time before copper-induced oxidation increased (13%). Reductions were observed in both the rate of oxidation (16%) and peak oxidation (20%). All of these changes should result in a dramatic reduction in the risk for atherosclerosis and its clinical sequelae.
Higher Serum Bilirubin Is Associated With Decreased Risk for Early Familial Coronary Artery Disease
Authors: Hopkins Paul N. , Wu Lily L. , Hunt Steven C. , James Brent C. , Vincent G. Michael , Williams Roger R.
Published: June 2011

AbstractMildly increased serum bilirubin has recently been suggested as a protective factor, possibly reducing the risk of coronary artery disease (CAD) by acting as an antioxidant. We tested this hypothesis by examining serum bilirubin concentrations and other coronary risk factors in 120 men and 41 women with early familial CAD and 155 control subjects. At screening, both cases and control subjects were 38 to 68 years old. Early familial CAD patients had experienced myocardial infarction, coronary artery bypass grafting, or coronary angioplasty by age 55 years for men and 65 for women and had another sibling similarly affected. The average total serum bilirubin concentration was 8.9±6.1 μmol/L in cases and 12.4±8.1 μmol/L in control subjects (P=.0001 for difference). In univariate analysis stratified by sex, serum bilirubin was strongly and inversely related to CAD risk, with relative odds of 0.4 to 0.1 (relative to the lowest quintile,P=.04 to .00001) in both men and women as bilirubin increased into the upper two quintiles. Multiple logistic regression analysis was performed including age, sex, smoking, body mass index, diabetes, hypertension, plasma measured LDL cholesterol, HDL cholesterol, triglycerides, and serum bilirubin as potential risk factors. Bilirubin entered as an independent protective factor with an odds ratio of 0.25 (P=.0015) for an increase of 17 μmol/L (1 mg/dL). The standardized logistic regression coefficient for bilirubin was −.33 compared with −.34 for HDL, suggesting that the protective effect of bilirubin on CAD risk in the population is comparable to that of HDL cholesterol. A history of cigarette smoking was associated with significantly lower serum bilirubin concentration and appeared to attenuate the protective effect of bilirubin.
Characteristics of the Insulin Resistance Syndrome in a Japanese Population
Authors: Kario Kazuomi , Nago Naoki , Kayaba Kazunori , Saegusa Tomohiro , Matsuo Hitoshi , Goto Tadao , Tsutsumi Akizumi , Ishikawa Shizukiyo , Kuroda Toshio , Miyamoto Takeshi , Matsuo Takefumi , Shimada Kazuyuki
Published: June 2011

Abstract
We investigated the relationships between hyperinsulinemia (a major indicator of the insulin resistance syndrome), blood pressure, dyslipidemia, and coagulation factors in 2606 community-dwelling Japanese individuals as part of the Jichi Medical School Cohort Study. An age-related decrease of the fasting insulin level was found in men but not in women. Body mass index, systolic and diastolic blood pressure, triglyceride and fasting glucose levels, and factor VII activity all increased in both sexes as the insulin level became higher, while the HDL cholesterol level decreased. In addition, total cholesterol and LDL cholesterol levels increased as the insulin level became higher and lipoprotein(a) levels decreased in the men. Fibrinogen levels were not related to the insulin level in either sex. Multiple logistic regression analysis revealed that fasting insulin levels were positively correlated with body mass index and fasting glucose and factor VII activity levels, whereas they were negatively correlated with HDL cholesterol in both sexes. In addition, fasting insulin levels were positively correlated with LDL cholesterol levels in men and with triglyceride levels in women. Our results indicate that hyperinsulinemia is associated with high factor VII activity in a general Japanese population as well as with high blood pressure and dyslipidemia. The accumulation of these cardiovascular risk factors in hyperinsulinemic subjects appears to contribute to cardiovascular events in the Japanese as well as in westerners.
Relation of Intima-Media Thickness to Atherosclerotic Plaques in Carotid Arteries
Authors: Bonithon-Kopp Claire , Touboul Pierre-Jean , Berr Claudine , Leroux Chantal , Mainard Francine , Courbon Dominique , Ducimetière Pierre
Published: June 2011

Abstract
This study examined the relation between arterial wall thickness and local atherosclerosis in the carotid arteries (CAs) and their specific risk factors. B-mode ultrasonography of the CAs was performed in a cohort of 516 men and 756 women aged 59 to 71 years who had been recruited for the European Vascular Aging Study. Ultrasound examination included measurement of intima-media thickness of the common CA (CCA) and the sites of plaque in the internal CA and bifurcations. Significant associations between increases in CCA intima-media thickness and both the presence and severity of atherosclerotic plaque were found in men and women. Examination of specific risk factors for increases in CCA intima-media thickness in the presence of plaque showed that, after adjustment for sex, both ultrasound measurements were independently related to age, body mass index, hypertension, and ever smoking (versus never smoking). Diabetes and current smoking were associated with intima-media thickness only, whereas hypercholesterolemia was related to plaque only. However, when subjects who were taking lipid-lowering drugs were excluded, lipoproteins and apolipoproteins were more consistently related to intima-media thickness than to plaque. In subjects free from any antihypertensive treatment, both intima-media thickness and plaques were independently associated with systolic blood pressure. After adjustment for sex and other risk factors, the odds ratio for having at least one plaque associated with a 0.10-mm increase in CCA intima-media thickness was 1.18 (95% confidence interval, 1.05 to 1.32). In this relatively aged population, increases in intima-media thickness as measured in the CCAs were clearly related to locally detected atherosclerosis and known risk factors for atherosclerosis. Longitudinal studies are needed to clarify the role of arterial wall thickening in the atherosclerotic process.
Fibrinogen Is a Predictor of Mortality in Coronary Heart Disease Patients
Authors: Benderly Michal , Graff Eran , Reicher-Reiss Henrietta , Behar Solomon , Brunner Daniel , Goldbourt Uri
Published: June 2011

Abstract
Results of epidemiological studies have indicated that fibrinogen is an important primary cardiovascular risk factor. The role of fibrinogen as a predictor of mortality in coronary heart disease (CHD) patients is unclear. We investigated the association between fibrinogen and mortality in a large cohort of CHD patients screened for participation in a secondary prevention clinical trial. Of the total investigated, 3092 men who were not included in the trial and for whom vital status was known were followed up for a mean period of 3.2 years. In 54.4% of the 111 men who died, mortality was attributed to CHD. Mean baseline plasma fibrinogen levels were 29.4 mg/dL higher in patients who died than in the survivors. All-cause and CHD mortality rates increased with increasing fibrinogen levels. This relationship was also demonstrated within categories of the primary variables predicting mortality in these patients. The contribution of fibrinogen to CHD and all-cause mortality was assessed by multivariate analysis adjusting for age, CHD severity, and comorbidity. Risks of CHD and all-cause mortality for patients in the highest fibrinogen tertile were 1.67 and 1.75, respectively, relative to patients in the lowest tertile, and an increase of about 1 SD of plasma fibrinogen level (75 mg/dL) was found to increase risk of CHD and all-cause mortality by 29% and 31%, respectively. These results indicate clearly that fibrinogen level is associated with significantly increased mortality in CHD patients. Implementation of a standardized measuring method is required to allow assessment of risk in CHD patients on the basis of fibrinogen levels.
Plasminogen Activator Inhibitor–1, Tissue-Type Plasminogen Activator, and Fibrinogen
Authors: Svendsen Ole Lander , Hassager Christian , Christiansen Claus , Nielsen Jørn Dalsgaard , Winther Kaj
Published: June 2011

Abstract
This study assessed the short- and long-term effects of an energy-restrictive diet with or without exercise on plasminogen activator inhibitor–1 antigen (PAI-1 Ag) and PAI-1 activity, tissue-type plasminogen activator antigen (TPA Ag), and fibrinogen serum levels. Healthy, overweight postmenopausal women (age, 53.8±2.5 years; body mass index, 25 to 42 kg/m
2
; n=121) were randomly assigned to one of three groups: control, 4200-kJ/d diet, or 4200-kJ/d diet with combined aerobic and anaerobic exercise. PAI-1 activity and PAI-1 Ag, TPA Ag, and fibrinogen levels were measured at baseline, after a 12-week intervention, and after a further 6-month follow-up. PAI-1 Ag and activity and TPA Ag were positively correlated with serum triglyceride levels, the abdominal-to–total-body fat ratio (as assessed by total-body dual-energy x-ray absorptiometry), fasting blood glucose, and systolic BP and negatively with HDL cholesterol and sex hormone–binding globulin. The diet led to profound decreases and normalization of PAI-1 activity (≈50%), PAI-1 Ag (≈30%), and TPA Ag (≈29%), but exercise conferred no additional effect. Fibrinogen did not change. At follow-up there were no longer any significant changes (
P
>.05). In conclusion, PAI-1 Ag and activity as well as TPA Ag seem to be part of the metabolic syndrome X. The diet made the blood less thrombogenic in the short term with no effect of the added exercise.
Contrary Effects of Lightly and Strongly Oxidized LDL With Potent Promotion of Growth Versus Apoptosis on Arterial Smooth Muscle Cells, Macrophages, and Fibroblasts
Authors: Björkerud Barbro , Björkerud Sören
Published: June 2011

AbstractThe inhibition of experimental atherosclerosis by antioxidants and the presence of oxidized LDL (oxLDL) in atherosclerotic lesions indicate that oxLDL may play what is perhaps a primary role in atherogenesis. LDL promotes the growth of arterial smooth muscle cells (SMCs), and oxLDL has cytotoxic effects. Since excessive intimal growth alternating with necrosis is typical of atherosclerotic lesions, we wondered whether these extreme changes in the lesions could be related to the extreme effects of LDL and oxLDL on cells. We therefore examined the effects of increasing LDL oxidation on its capacity to induce cell growth or cell death and whether the latter could be due to apoptosis. Cells of the types present in the atherosclerotic artery were used, ie, SMCs (human arterial), macrophages (human macrophage-like cell line THP-1), and human fibroblasts. Growth was evaluated by measuring the synthesis of DNA and culture size (MTT method) and apoptosis by using the in situ labeling of internucleosomally degraded DNA and, in the case of SMCs, the appearance of chromatin condensation. The oxidation of LDL was mediated by UV or Fe ions. Shortly oxidized LDL had a markedly increased growth-promoting effect on all cell types. With prolonged exposure to UV, but not to Fe, LDL became increasingly cytotoxic, and this toxicity was paralleled by the appearance of apoptosis in all cell types. After prolonged UV treatment, low-molecular-weight material from the partially degraded LDL was responsible for the induction of apoptosis. The dual effect of oxLDL, ie, its strong growth-promoting effect or the induction of cell death by apoptosis, depending on the degree of change by oxidation, is compatible with the notion that oxLDL plays a role not only in atherogenesis but also more extensively in the development of the structure typical of the atherosclerotic lesion, with focal excessive growth alternating with necrosis.
Cosupplementation With Coenzyme Q Prevents the Prooxidant Effect of α-Tocopherol and Increases the Resistance of LDL to Transition Metal–Dependent Oxidation Initiation
Authors: Thomas Shane R. , Neužil Jiří , Stocker Roland
Published: June 2011

Abstract
There is considerable interest in the ability of antioxidant supplementation, in particular with vitamin E, to attenuate LDL oxidation, a process implicated in atherogenesis. Since vitamin E can also promote LDL lipid peroxidation, we investigated the effects of supplementation with vitamin E alone or in combination with coenzyme Q on the early stages of the oxidation of isolated LDL. Isolated LDL was obtained from healthy subjects before and after in vitro enrichment with vitamin E (
d
-α-tocopherol, α-TOH) or dietary supplementation with
d
-α-TOH (1 g/d) and/or coenzyme Q (100 mg/d). LDL oxidation initiation was assessed by measurement of the consumption of α-TOH and cholesteryl esters containing polyunsaturated fatty acids and the accumulation of cholesteryl ester hydroperoxides during incubation of LDL in the transition metal–containing Ham’s F-10 medium in the absence and presence of human monocyte-derived macrophages (MDMs). Native LDL contained 8.5±2 molecules of α-TOH and 0.5 to 0.8 molecules of ubiquinol-10 (CoQ
10
H
2
, the reduced form of coenzyme Q) per lipoprotein particle. Incubation of this LDL in Ham’s F-10 medium resulted in a time-dependent loss of α-TOH with concomitant stoichiometric conversion of the major cholesteryl esters to their respective hydroperoxides. MDMs enhanced this process. LDL lipid peroxidation occurred via a radical chain reaction in the presence of α-TOH, and the rate of this oxidation decreased on α-TOH depletion. In vitro enrichment of LDL with α-TOH resulted in an LDL particle containing sixfold to sevenfold more α-TOH, and such enriched LDL was more readily oxidized in the absence and presence of MDMs compared with native LDL. In vivo α-TOH–deficient LDL, isolated from a patient with familial isolated vitamin E deficiency, was highly resistant to Ham’s F-10–initiated oxidation, whereas dietary supplementation with vitamin E restored the oxidizability of the patient’s LDL. Oral supplementation of healthy individuals for 5 days with either α-TOH or coenzyme Q increased the LDL levels of α-TOH and CoQ
10
H
2
by two to three or three to four times, respectively. α-TOH–supplemented LDL was significantly more prone to oxidation, whereas CoQ
10
H
2
-enriched LDL was more resistant to oxidation initiation by Ham’s F-10 medium than native LDL. Cosupplementation with both α-TOH and coenzyme Q resulted in LDL with increased levels of α-TOH and CoQ
10
H
2
, and such LDL was markedly more resistant to initiation of oxidation than native or α-TOH–enriched LDL. These results demonstrate that oral supplementation with α-TOH alone results in LDL that is more prone to oxidation initiation, whereas cosupplementation with coenzyme Q not only prevents this prooxidant activity of vitamin E but also provides the lipoprotein with increased resistance to oxidation.
‘Silent’ Cerebral Infarction Is Associated With Hypercoagulability, Endothelial Cell Damage, and High Lp(a) Levels in Elderly Japanese
Authors: Kario Kazuomi , Matsuo Takefumi , Kobayashi Hiroko , Asada Reiko , Matsuo Miyako
Published: June 2011

Abstract
“Silent” lacunar stroke, often found in the elderly, has been proposed as a predisposing condition for clinically overt stroke. However, the risk factors related to this condition have not been studied thoroughly. We conducted brain magnetic resonance imaging and measured the levels of fibrinogen, molecular markers of coagulation activation [prothrombin fragment 1+2 (F1+2)] and endothelial cell damage [von Willebrand factor (vWF) and thrombomodulin], and lipid profiles including lipoprotein (a) [Lp(a)] in 178 asymptomatic, high-risk, Japanese subjects aged 44 to 93 years. We also studied 32 symptomatic patients with lacunar stroke (symptomatic lacunar group). The prevalence of silent lacunar stroke increased with age up to 85 years but decreased with age in those 85 years old and older. Of the 160 elderly subjects (≥60 years) 84 (53%) had ≥1 lacunar infarcts (silent lacunar group) and the remaining 76 were considered as the nonlacunar group. Fibrinogen and F1+2 levels in the silent lacunar group were significantly higher than those in the nonlacunar group (
P
<.01). Mean Lp(a) levels and the prevalence of subjects with an Lp(a) level >30 mg/dL were significantly higher in the symptomatic lacunar group than the nonlacunar group (
P
<.05), whereas these levels in the silent lacunar group were intermediate to those of the other two groups. When we further classified the silent lacunar group into three subgroups based on the number of lacunes (few lacunes, 1 or 2; moderate number of lacunes, 3 or 4; and numerous lacunes, ≥5), levels of Lp(a), F1+2, vWF, and thrombomodulin were significantly higher and Lp(a) levels >30 mg/dL more common in the numerous-lacune than in the few-lacune subgroup. We conclude that silent lacunar stroke is often found in asymptomatic, high-risk, elderly Japanese patients and that silent multiple lacunar stroke is associated with hypercoagulability, endothelial cell damage, and high Lp(a) levels.
Fenofibrate Reduces Plasma Cholesteryl Ester Transfer From HDL to VLDL and Normalizes the Atherogenic, Dense LDL Profile in Combined Hyperlipidemia
Authors: Guérin Maryse , Bruckert Éric , Dolphin Peter J. , Turpin Gérard , Chapman M. John
Published: June 2011

Abstract
The effect of fenofibrate on plasma cholesteryl ester transfer protein (CETP) activity in relation to the quantitative and qualitative features of apoB- and apoA-I–containing lipoprotein subspecies was investigated in nine patients presenting with combined hyperlipidemia. Fenofibrate (200 mg/d for 8 weeks) induced significant reductions in plasma cholesterol (−16%;
P
<.01), triglyceride (−44%;
P
<.007), VLDL cholesterol (−52%;
P
=.01), LDL cholesterol (−14%;
P
<.001), and apoB (−15%;
P
<.009) levels and increased HDL cholesterol (19%;
P
=.0001) and apoA-I (12%;
P
=.003) levels. An exogenous cholesteryl ester transfer (CET) assay revealed a marked decrease (−26%;
P
<.002) in total plasma CETP-dependent CET activity after fenofibrate treatment. Concomitant with the pronounced reduction in VLDL levels (37%;
P
<.005), the rate of CET from HDL to VLDL was significantly reduced by 38% (
P
=.0001), whereas no modification in the rate of cholesteryl ester exchange between HDL and LDL occurred after fenofibrate therapy. Combined hyperlipidemia is characterized by an asymmetrical LDL profile in which small, dense LDL subspecies (LDL-4 and LDL-5,
d
=1.039 to 1.063 g/mL) predominate. Fenofibrate quantitatively normalized the atherogenic LDL profile by reducing levels of dense LDL subspecies (−21%) and by inducing an elevation (26%;
P
<.05) in LDL subspecies of intermediate density (LDL-3,
d
=1.029 to 1.039 g/mL), which possess optimal binding affinity for the cellular LDL receptor. However, no marked qualitative modifications in the chemical composition or size of LDL particles were observed after drug treatment. Interestingly, the HDL cholesterol concentration was increased by fenofibrate therapy, whereas no significant change was detected in total plasma HDL mass. In contrast, the HDL subspecies pattern was modified as the result of an increase in the total mass (11.7%) of HDL
2a
, HDL
3a
, and HDL
3b
(
d
=1.091 to 1.156 g/mL) at the expense of reductions in the total mass (−23%) of HDL
2b
(
d
=1.063 to 1.091 g/mL) and HDL
3c
(
d
=1.156 to 1.179 g/mL). Such changes are consistent with a drug-induced reduction in CETP activity. In conclusion, the overall mechanism involved in the fenofibrate-induced modulation of the atherogenic dense LDL profile in combined hyperlipidemia primarily involves reduction in CET from HDL to VLDL together with normalization of the intravascular transformation of VLDL precursors to receptor-active LDLs of intermediate density.
A Cytotoxic Electronegative LDL Subfraction Is Present in Human Plasma
Authors: Demuth Karine , Myara Isaac , Chappey Béatrice , Vedie Benoit , Pech-Amsellem Marie Agnès , Haberland Margaret E. , Moatti Nicole
Published: June 2011

Abstract
By using fast protein liquid chromatography, we isolated from human plasma a minor electronegative LDL subfraction designated LDL(−). After immunoaffinity chromatography against apolipoprotein (apo)(a) and apo A-I, LDL(−) represented 6.7±0.9% (mean±SD; n=18) of total LDL. Compared with the major LDL subfraction, designated LDL(+), LDL(−) contained similar amounts of thiobarbituric acid–reactive substances, conjugated dienes, and vitamin E and had a similar lipid/protein ratio and mean density. Moreover, the apo B of LDL(−) was not aggregated and its LDL receptor–binding activity was slightly increased. These results were consistent with the nonoxidized nature of LDL(−). LDL(−) showed increased contents of sialic acid (38.1±5.2 versus 28.9±3.3 nmol/mg protein; n=7;
P
<.01), apo C-III (1.43±0.21% versus 0.14±0.04%; n=7;
P
<.01), and apo E (1.64±0.26% versus 0.10±0.05%; n=7;
P
<.0005). Compared with LDL(+), LDL(−) displayed enhanced cytotoxic effects on cultured human umbilical vein endothelial cells, as shown by lactate dehydrogenase assay (
P
<.003; n=6), neutral red uptake (
P
<.02; n=6), and morphological studies. We also studied the relationship of LDL(−) to age and plasma lipid levels in 133 subjects. The percentage of contribution of LDL(−) to total plasma LDL correlated with age (
P
<.05), total cholesterol (
P
<.05), and LDL cholesterol (
P
<.003). In conclusion, this study shows that LDL(−), a circulating human plasma LDL, is an electronegative native LDL subfraction with cytotoxic effects on endothelial cells. This subfraction, which correlates positively with common atherosclerotic risk factors, might induce atherogenesis by actively contributing to alteration of the vascular endothelium.
Differences in Receptor Binding of LDL Subfractions
Authors: Campos Hannia , Arnold Kay S. , Balestra Maureen E. , Innerarity Thomas L. , Krauss Ronald M.
Published: June 2011

AbstractDifferences in low density lipoprotein (LDL) receptor-binding affinity among LDL particles of different size were examined in competitive binding assays in human skin fibroblasts and LDL (d=1.020 to 1.050 g/mL) from subjects with a predominance of large (≥272 Å), medium (259 to 271 Å), and small (≤257 Å) LDL. Among 57 normolipidemic subjects with LDL cholesterol (-C) levels <160 mg/dL, binding affinity was reduced by 16% in those with predominantly large LDL and by 14% in those with small LDL compared with most subjects who had a predominance of medium-size LDL and in all LDL size subgroups in 66 subjects with LDL-C ≥160 mg/dL. Differences in LDL receptor-binding affinity were further investigated by using LDL density subfractions (I,d=1.026 to 1.032 g/mL; II,d=1.032 to 1.038 g/mL; and III,d=1.038 to 1.050 g/mL) from three subjects with predominantly large (pattern A) and small (pattern B) LDL particles. The binding affinity (Kd) of LDL-II was similar for patterns A and B (9.2±1.4 and 9.4±0.7, respectively) and 30% lower in LDL-III from both groups (P<.05). The binding affinity of LDL-I in pattern A (12.6±1.5 μg/mg) was lower (P<.05) than that in LDL-II and LDL-I from pattern B (8.0±2.4 μg/mg). After incubation with a monoclonal antibody that specifically blocked the LDL receptor-binding domain of apoE, LDL-I from two pattern B subjects showed substantially lower binding affinity (Kd=20.0 and 19.2 μg/mg) than in pattern A (Kd=13.2 and 14.2 μg/mg), a result consistent with our finding of a higher apoE content in pattern B LDL-I (P<.001). Thus, factors associated with variations in particle size and apoE content in LDL subclasses in normolipidemic subjects contribute to the differences in LDL receptor binding that may result in differing metabolic behavior in vivo.
Distinct Rat Aortic Smooth Muscle Cells Differ in Versican/PG-M Expression
Authors: Lemire Joan M. , Potter-Perigo Susan , Hall Keith L. , Wight Thomas N. , Schwartz Stephen M.
Published: June 2011

Abstract
Smooth muscle cells (SMCs) with distinct phenotypes are present in blood vessels, and distinct culture types appear when SMCs are maintained in vitro. For example, cultured SMCs from rat adult media grow as bipolar cells, which differ in gene expression from the predominantly cobblestone-shaped SMCs from rat pup aortas and rat neointimas that we call π SMCs. Since proteoglycans are present at different concentrations in the normal intima and media and are elevated in atherosclerotic plaque, we sought to determine whether π and adult medial SMC types synthesize different or unique proteoglycans that are characteristic of each phenotype. [
35
S]sulfate-labeled proteoglycans were purified by ion-exchange chromatography. An adult medial SMC line synthesized a large proteoglycan (0.2 K
av
on Sepharose CL-2B) that was not detectable in a π SMC line. Digestion of this proteoglycan with chondroitin ABC lyase revealed three core glycoproteins of 330, 370, and 450 kD. By Western blot analysis, the two smallest of these reacted with two antibodies to the human fibroblast proteoglycan versican. RNAs hybridizing to versican probes were found only in adult medial–type SMCs, including an adult medial type clone from pup aorta, by Northern blot analysis. Both SMC types synthesize RNAs that hybridize to probes for other proteoglycans, such as perlecan, biglycan, and decorin. We conclude that rat π SMC cultures, unlike monkey, human, and rat adult medial SMC cultures, express little or no versican. This difference in expression may be responsible for the different morphologies and growth properties of the two cell types.
Antibodies to CD36 (GPIV) Inhibit Platelet Adhesion to Subendothelial Surfaces Under Flow Conditions
Authors: Diaz-Ricart Maribel , Tandon Narendra N. , Gómez-Ortiz Goretti , Carretero Marta , Escolar Ginés , Ordinas Antonio , Jamieson G.A.
Published: June 2011

The membrane glycoprotein CD36 (glycoprotein [GP] IV) has previously been shown to accelerate the initial interaction of platelets with purified type I collagen in both static and flow systems. In the present study, the role of CD36 on platelet interaction with physiologically relevant collagenous surfaces was addressed. Using arterial subendothelium (SE) and endothelial cell extracellular matrix (ECM), studies were performed under flow conditions with annular and parallel-plate perfusion chambers, respectively, at a shear rate of 800 s
−1
for 2, 5, and 10 minutes. Perfusates consisted of citrated normal blood samples incubated with Fab fragments of a monospecific polyclonal anti-CD36 antibody or with each of three new anti-CD36 monoclonal antibodies (MoAbs) that inhibit platelet adhesion to purified type I collagen in a static system (131.4, 131.5, and 131.7). Perfusions over SE were also carried out using citrated blood samples from a Nak
a
-negative donor, whose platelets lack CD36. Morphometric evaluation of the perfused samples showed that polyclonal anti-CD36 Fab and the three monoclonal anti-CD36 antibodies inhibited platelet adhesion to the two substrates by 40% after 2 minutes of perfusion and by 30% after 5 minutes (
P
<.005 on SE and
P
<.01 on ECM), but at 10 minutes, significant inhibition was seen only on SE with polyclonal anti-CD36 Fab. Similar inhibitions were seen with Nak
a
-negative platelets on SE. These studies demonstrate that CD36 plays a role in the early stages of platelet adhesion to physiologically relevant subendothelial surfaces.
Interleukin-8 Production by Macrophages From Atheromatous Plaques
Authors: Apostolopoulos Jim , Davenport Piers , Tipping Peter G.
Published: June 2011

Interleukin-8 (IL-8) is a chemotactic peptide produced by macrophages that may be involved in the recruitment of inflammatory cells into atherosclerotic plaques. In vitro, IL-8 production by macrophages isolated from carotid plaques (1240±510 pg·10
5
cells
−1
·24 h
−1
, mean±SEM, n=6) and noncarotid plaques (4312±1588 pg·10
5
cells
−1
·24 h
−1
, n=9) was significantly greater than IL-8 production by blood monocytes isolated from the same patients (526±278 pg·10
5
cells
−1
·24 h
−1
, n=6,
P
<.05 and 726±384 pg·10
5
cells
−1
·24 h
−1
, n=9,
P
<.01, respectively). IL-8 produced by atherosclerotic macrophages was demonstrated to be biologically active in a neutrophil chemotaxis assay. IL-8 mRNA was detectable in plaque macrophages and blood monocytes from these patients, but blood monocytes from normal donors did not exhibit detectable IL-8 mRNA. IL-8 mRNA was localized in macrophage-rich areas of atherosclerotic plaques by in situ hybridization. These studies demonstrate that macrophages from atherosclerotic plaques show an enhanced capacity to produce IL-8 compared with normal and patient blood monocytes and that macrophages are a major site of IL-8 mRNA production in atherosclerotic plaques. These results provide further evidence for a proinflammatory role for macrophages in atherosclerosis.
Regulation of Monocyte CD36 and Thrombospondin-1 Expression by Soluble Mediators
Authors: Yesner Lewis M. , Huh Ho Young , Pearce S. Frieda , Silverstein Roy L.
Published: June 2011

CD36 is an 88-kD integral membrane protein expressed on platelets, monocytes, macrophages, certain microvascular endothelia, and retinal pigment epithelium. It functions as an adhesive receptor for thrombospondin-1 (TSP-1), collagen, and malaria-infected erythrocytes and as a scavenger receptor for oxidized LDL and photoreceptor outer segments. The CD36–TSP-1 interaction plays a role in cell adhesion and the phagocytosis of apoptotic cells by macrophages. Because of the potential importance of the CD36–TSP-1 interaction in mediating atherogenic and inflammatory processes, we studied their expression in human peripheral blood monocytes exposed to soluble mediators known to regulate inflammation and atherogenesis. RNase protection assays showed 6- to 12-fold increases in CD36 mRNA in response to interleukin-4, monocyte colony-stimulating factor, and phorbol myristate acetate, while lipopolysaccharide and dexamethasone strongly downregulated CD36 mRNA. The downregulation of CD36 mRNA was associated with the disappearance of surface expression of CD36 antigen and loss of TSP-1 surface-binding capacity. Upregulation of CD36 mRNA was associated with a modest increase in surface antigen expression and a larger expansion of an intracellular pool of CD36. As with CD36, monocytes treated with monocyte colony-stimulating factor showed a rapid increase in TSP-1 mRNA expression. Moreover, while dexamethasone treatment decreased CD36 expression, it resulted in a rapid increase in TSP-1 mRNA, and while PMA increased CD36 mRNA, it rapidly decreased TSP-1 expression. Interferon gamma, which had no effect on CD36 mRNA, rapidly increased steady-state TSP-1 mRNA. Thus, expression of both CD36 and its ligand TSP-1 is regulated by soluble mediators, although certain mediators induce concordant changes and others discordant changes.
Identification on Human CD36 of a Domain (155-183) Implicated in Binding Oxidized Low-Density Lipoproteins (Ox-LDL)
Authors: Navazo Marta D. Puente , Daviet Laurent , Ninio Ewa , McGregor John L.
Published: June 2011

Uptake of oxidized LDL (oxLDL) by macrophages is one of the key events implicated in the initiation and perpetuation of atherosclerotic lesions. One of the major scavenging receptors, which binds modified LDL, on macrophages is CD36. The domain on CD36 implicated in the binding of oxLDL remains to be elucidated. In this study, COS cells transfected with human CD36 cDNA bound FITC-oxidized human LDL in a dose-dependent, saturable manner. This binding was inhibited by an excess of oxLDL but not by native LDL. Anti-CD36 monoclonal antibodies (mAbs) 10/5, FA6-152, and 8A6 (directed against domain 155-183), but not mAb 13/10 (directed against domain 30-76), completely inhibited oxLDL binding to human CD36-transfected COS cells. Cells transfected with a chimeric human CD36 construct (hmh 155-183), resulting from the swapping of human domain 155-183 with its murine counterpart, resulted in low binding of oxLDL. In contrast, cells transfected with a chimeric murine CD36 construct (mhm 155-183), resulting from the swapping of murine domain 155-183 with its human counterpart, resulted in high binding of oxidized human LDL. Binding of oxLDL to cells transfected by chimeric construct mhm 155-183 were only partially blocked by mAbs 10/5, FA6-152, and 8A6. In the present study we have identified, for the first time, an important functional domain (encompassing amino acids 155-183) on CD36 involved in the binding of oxLDL. In addition, the binding site for oxidized human LDL on murine CD36 seems to differ from its human counterpart.