bluuebunny/crossref_metadata_2025 huggingface dataset:
Predominance of Large LDL and Reduced HDL
2
Cholesterol in Normolipidemic Men With Coronary Artery Disease
Authors: Campos Hannia , Roederer Ghislaine O. , Lussier-Cacan Suzanne , Davignon Jean , Krauss Ronald M.
Published: June 2011

Abstract
Previous studies have indicated that a predominance of small, dense LDL particles is associated with coronary artery disease (CAD) risk. In the present study we examined the LDL peak particle diameter (determined by lipid-stained 2% to 16% gradient gel electrophoresis) in 92 normolipidemic men with CAD (total cholesterol <200 mg/dL and triglyceride <250 mg/dL) and 92 matched healthy controls. Plasma triglyceride, LDL cholesterol, and apo B levels were similar in subjects with CAD and in control subjects, whereas subjects with CAD had decreased HDL
2
cholesterol levels (mean±SEM, 10±0.7 compared with 15±0.7 mg/dL in control subjects;
P
<.0002). Mean LDL particle diameter (±SEM) was increased in the subjects with CAD compared with control subjects (26.8±0.08 and 26.4±0.08 nm, respectively;
P
<.001). The association between large LDL size and CAD was significant (
P
<.0001) after adjustments were made for age, body mass index, HDL cholesterol levels, and VLDL cholesterol levels. An LDL particle size distribution characterized by a predominance of the largest of three classes of LDL particles (>26.8 nm) was more prevalent among subjects with CAD (43%) than among control subjects (25%) (
P
<.002). Among subjects with this LDL size profile, subjects with CAD had significantly higher (
P
<.05) VLDL triglyceride, VLDL cholesterol, and VLDL apo B levels and significantly lower (
P
<.0001) HDL
2
cholesterol levels than controls. Thus, in this normolipidemic population with CAD, a predominance of very large rather than small LDL particles was associated with increased VLDL and reduced HDL
2
cholesterol levels and with increased CAD risk, independent of other plasma lipid and lipoprotein levels.
Effects of Different Phenotypes of Hyperlipoproteinemia and of Treatment With Fibric Acid Derivatives on the Rates of Cholesterol 7α-Hydroxylation in Humans
Authors: Bertolotti Marco , Concari Mauro , Loria Paola , Abate Nicola , Pinetti Adriano , Guicciardi M. Eugenia , Carulli Nicola
Published: June 2011

Abstract
Little is known about the relationships between hyperlipidemia and bile acid metabolism. However, hypolipidemic treatment with fibric acid derivatives has been shown to increase biliary cholesterol secretion, presumably by reducing bile acid synthesis. To clarify such relationships, we investigated the effects of different hyperlipoproteinemic conditions and of treatment with fibric acid derivatives on the rates of cholesterol 7α-hydroxylation (the limiting step of bile acid synthesis) in humans. We studied 10 patients (aged 36 to 68 years) with lipoprotein phenotype IIa and with a clinical diagnosis of heterozygous familial hypercholesterolemia, a condition of reduced activity of LDL receptors, and 11 patients (aged 48 to 70 years) with lipoprotein phenotype IIb or IV and clinical diagnosis of familial combined hyperlipidemia, a condition probably related to increased hepatic lipoprotein synthesis. Cholesterol 7α-hydroxylation rates were assayed in vivo by tritium release assay after an intravenous injection of [7α-
3
H]cholesterol. The results were compared by ANOVA to the values obtained in a group of 28 normolipidemic patients (aged 34 to 83 years), with age as the covariate. Six patients were also studied after treatment with gemfibrozil (900 to 1200 mg/d for 6 to 8 weeks) and 5 patients were studied after treatment with bezafibrate (400 mg/d for 6 to 8 weeks). Hydroxylation rates were 0.82±0.22 mmol/d in the familial hypercholesterolemia group and 1.30±0.47 mmol/d in the familial combined hyperlipidemia group (
P
<.05 between the two groups and between patients with familial combined hyperlipidemia and control subjects;
P
=NS between patients with familial hypercholesterolemia and control subjects, as determined by ANOVA). Treatment with both gemfibrozil and bezafibrate reduced serum cholesterol, slightly increased HDL cholesterol, and significantly reduced serum triglyceride and apo B concentrations. Cholesterol 7α-hydroxylation rates were significantly reduced by nearly 55% both after gemfibrozil and after bezafibrate. Our findings indirectly suggest that cholesterol degradation to bile acid is independent of receptor-mediated uptake of LDL by the liver. Hydroxylation rates seem to parallel serum levels of triglyceride and apo B (particularly after fibrate treatment), possibly suggesting a coordinate regulation of bile acid and lipoprotein synthesis.
Low Atherosclerotic Response of a Strain of Rabbits to Diet-Induced Hypercholesterolemia
Authors: Thiery Joachim , Nebendahl Klaus , Rapp Karl , Kluge Reinhart , Teupser Daniel , Seidel Dietrich
Published: June 2011

AbstractIn this report we describe the development of two rabbit strains, HAR (high atherosclerotic response) and LAR (low atherosclerotic response), and their propensities to develop atherosclerosis in the aorta despite similar levels of diet-induced hypercholesterolemia. Sixty-two randomly selected male New Zealand White rabbits were fed a cholesterol-enriched diet (0.5%) for 84 days and developed 57±25% sudanophilic lesions of the aortic surface; 12 rabbits showed a low atherosclerotic response (0% to 30% surface involvement), and 22 rabbits showed a high atherosclerotic response (70% to 100% surface involvement). The offspring of rabbits with low atherosclerotic response were used for breeding the strain of rabbits resistant to atherosclerosis (LAR strain), while the offspring of rabbits with high atherosclerotic response were used for breeding the HAR strain. Controlled breeding was started after the 4th generation and performed for the subsequent 6 generations. Thus, in the LAR rabbits the lipid-stainable surface area of aorta amounted to only 27±17% after 112 days of cholesterol feeding. On the other hand, in HAR rabbits, aortic surface involvement reached 85±25% after 112 days on the cholesterol-enriched diet. The measurements of surface area involvement were corroborated also by a significantly lower, chemically determined cholesterol content of the aorta in LAR rabbits. Plasma lipids and lipoproteins were determined at baseline, after 21 and 42 days of cholesterol feeding, and at the time the animals were killed. The plasma cholesterol concentrations of cholesterol-fed HAR and LAR rabbits showed a 13-fold increase after 21 days and a 21-fold increase after 84 days on the cholesterol diet. The development of hypercholesterolemia was similar in both rabbit strains. At the time the animals were killed, the plasma concentrations in the HAR and LAR rabbits were 1241±489 mg/dL and 1370±473 mg/dL, respectively. There was a comparable effect of cholesterol feeding on the plasma VLDL, IDL, and LDL levels, but no significant differences were observed in plasma HDL cholesterol levels. The degree of genetic diversity between the two rabbit strains was studied in inherited protein polymorphism of plasma and erythrocytes. The alleles of six protein markers segregated in both rabbit strains, with significant differences at theEs-1and thePgdloci. The outbred strain of LAR rabbits appears to represent a model of inherited resistance to the development of atherosclerosis.
Presence and Formation of ‘Free Apolipoprotein A-I–Like’ Particles in Human Plasma
Authors: Asztalos Bela F. , Roheim Paul S.
Published: June 2011

Abstract
The influence of dilution on apolipoprotein (apo) A-I–containing subpopulations was studied in human plasma. Agarose electrophoresis and two-dimensional agarose nondenaturing gradient polyacrylamide gel electrophoresis were used. Both in one- and two-dimensional electrophoresis, an increase of charge was observed that resulted in an increase of subpopulations with pre-α mobility. Dilution of plasma also resulted in a decrease in the size of apo A-I–containing pre-β
1
subpopulations. The existence of smaller pre-β
1
particles was confirmed by subjecting undiluted and 8× diluted plasma to 3% to 16% nondenaturing gradient gel electrophoresis for 4 hours. In addition to the generally observed pre-β
1
subpopulations, smaller particles similar in size to the free apo A-I were detected even in the undiluted plasma. During dilution, the proportion of larger pre-β
1
particles decreased while the smaller ones increased, and in 8× diluted plasma, almost all the pre-β
1
was present in smaller sizes. Using 3% to 35% nondenaturing polyacrylamide gels run for 24 hours, no pre-β
1
particles could be detected in 8× diluted plasma because the small pre-β
1
electrophoresed out. These studies show that pre-β
1
particles can be converted to smaller ones during dilution. It also was demonstrated that “free apo A-I–like” pre-β
1
particles are present in undiluted plasma. The presence of these particles may have important physiological and pathophysiological functions.
Plasma Concentration of Apolipoprotein E in Intermediate-Sized Remnant-Like Lipoproteins in Normolipidemic and Hyperlipidemic Subjects
Authors: Cohn Jeffrey S. , Tremblay Michel , Amiot Mireille , Bouthillier Daniel , Roy Madeleine , Genest Jacques , Davignon Jean
Published: June 2011

Abstract
Triglyceride-rich lipoprotein (TRL) remnants have been strongly implicated in the pathogenesis of atherosclerosis. To further investigate plasma remnant lipoprotein metabolism, we have determined the plasma concentration of apolipoprotein (apo) E (by polyclonal enzyme-linked immunoassay) in remnant-like lipoproteins, isolated by automated gel filtration chromatography as a fraction intermediate in size between VLDL and HDL. In normolipidemic subjects (n=12), 1.2±0.1 mg/dL (33±2%, mean±SE) of total plasma apoE was associated with this fraction (termed ISL apoE). In hypercholesterolemic (type IIa, n=12), hypertriglyceridemic (type IV, n=12), and mixed hyperlipidemic (type IIb, n=12) subjects, mean ISL apoE concentrations were 2.1±0.2, 2.5±0.2, and 3.8±0.4 mg/dL, respectively (
P
<.001 versus normal values) (45±2%, 32±2%, and 44±2% of total). ISL apoE was 8.7±1.4 mg/dL (42±3%) in type III dyslipidemic subjects (apoE2/2, n=8). ISL apoE was positively correlated with plasma triglyceride (
r
=.41,
P
<.01), and at any given level of plasma triglyceride, subjects with an apoE2/2 or apoE3/2 phenotype tended to have a higher concentration of ISL apoE (
P
<.01) than apoE3/3 or E4/3 individuals. ISL apoE was also correlated (
P
<.001) with total plasma cholesterol (
r
=.66), TRL cholesterol (
r
=.49), TRL apoE (
r
=.47), LDL apoB (
r
=.42), and LDL+HDL triglyceride (
r
=.74). These results suggest that (1) a significant proportion of plasma apoE resides within an intermediate-sized remnant-like lipoprotein fraction in both normolipidemic and hyperlipidemic subjects; (2) plasma remnant lipoprotein accumulation is associated with an elevation in ISL apoE concentration; and (3) ISL apoE concentration is significantly correlated with various proatherogenic lipid parameters and may itself be a potentially important atherogenic index.
Comparison of the Effects of the Thrombin Inhibitor r-Hirudin in Four Animal Models of Neointima Formation After Arterial Injury
Authors: Gerdes Christoph , Faber-Steinfeld Verona , Yalkinoglu Özkan , Wohlfeil Stefan
Published: June 2011

Thrombin has been implicated as a contributing factor to restenosis after vessel reopening procedures. We compared the ability of the direct thrombin inhibitor recombinant (r-) hirudin to reduce neointimal growth in different animal models of arterial injury. Carotid arteries of rats, rabbits, and hypercholesterolemic minipigs were injured by withdrawal of an inflated balloon catheter. In addition, we used a double-lesion model in rabbits, which involved balloon angioplasty of a preexisting lesion induced by carotid denudation 4 weeks earlier. r-Hirudin was given in all four animal models as a short-term application (bolus of 1 mg/kg IV immediately before injury, followed by infusion of 1 mg · kg
−1
 · h
−1
for 2 hours, and an injection of 6 mg/kg SC). Additionally, we investigated the effects of prolonged treatment (intravenous infusion for 3 and 14 days) in rats. Inhibition of thrombin was monitored by determination of activated partial thromboplastin time, and histomorphometric analysis of the arteries was performed after 2 (rats) or 4 (rabbits and minipigs) weeks. In rabbits, short-term r-hirudin treatment reduced neointimal area by 59% (single-injury model,
P
=.05) and 44% (double-injury model,
P
=.02). In rats and minipigs no inhibition of neointimal growth was observed after short-term r-hirudin application. A 3- or 14-day infusion of r-hirudin in rats, however, resulted in 25% (
P
=.007) and 27% (
P
=.003) reductions in neointimal area, respectively. In conclusion, there is considerable interspecies variation in the time frame of susceptibility for reduction of neointimal growth by inhibition of thrombin after arterial injury. These results demonstrate the importance of testing potential antirestenotic treatments in an array of different animal models.
Osteopontin Expression in Platelet-Derived Growth Factor–Stimulated Vascular Smooth Muscle Cells and Carotid Artery After Balloon Angioplasty
Authors: Wang Xinkang , Louden Calvert , Ohlstein Eliot H. , Stadel Jeffrey M. , Gu Juan-Li , Yue Tian-Li
Published: June 2011

Osteopontin (OPN), an arginine-glycine-aspartate (RGD)–containing adhesive glycoprotein, is constitutively expressed in rat aorta and carotid arteries and is markedly elevated in response to vascular injury. OPN is chemotactic for vascular smooth muscle cells (SMCs), suggesting a role in vascular remodeling. However, the mechanism for the regulation of OPN expression is poorly understood. In the present study, the effect of platelet-derived growth factor (PDGF) on OPN mRNA expression was investigated in cultured rat aortic SMCs (RASMCs). When RASMCs were stimulated with 1 nmol/L PDGF, a 2.4-fold increase in OPN mRNA expression was observed at 3 hours (
P
<.05) that peaked at 14 hours with a 6.7-fold increase (
P
<.001). This induction was blocked by a monoclonal anti-PDGF antibody. Further studies revealed that OPN mRNA expression was induced by PDGF-AB or PDGF-BB but not by PDGF-AA, indicating that only the β-type PDGF receptor mediates this response. Compared with basic fibroblast growth factor, epidermal growth factor, transforming growth factor-β, and interleukin-1β, PDGF was the most potent factor studied to induce OPN mRNA expression in RASMCs. Immunohistochemical studies demonstrated the elevation of OPN protein in PDGF-stimulated RASMCs. The temporal expression of OPN mRNA after rat carotid artery balloon angioplasty as assessed by both reverse transcription–polymerase chain reaction and Northern blot analysis revealed a 1.5-fold increase at 6 hours (
P
<.01) that peaked at 1 and 3 days with a 3.1-fold increase (
P
<.001). Immunohistochemical studies of carotid artery after angioplasty localized OPN expression in the medial SMCs at 1 day, ie, at a time of significant platelet adherence to the injured vessel, and thereafter to the intimal lesion during neointimal formation. These data suggest that OPN expression in vascular SMCs is regulated by PDGF through the β-type PDGF receptor in vitro, and possibly in vivo, in situations that involve PDGF released from platelets or other cellular sources, such as blood vessels after angioplasty injury.
Ischemia-Induced Transplant Arteriosclerosis in the Rat
Authors: Waltenberger Johannes , Akyürek M. Levent , Aurivillius Magnus , Wanders Alkwin , Larsson Erik , Fellström Bengt , Funa Keiko
Published: June 2011

Peptide growth factors have been reported to contribute to the atherogenic process, and they are known to mediate signals for vascular remodeling. Using syngeneic and allogeneic rat aorta transplant models, we analyzed the impact of cold ischemia time up to 24 hours and reperfusion injury on development of transplant arteriosclerosis during the first 2 months after transplantation. The expression of the transforming growth factor-β (TGF-β) family as well as the platelet-derived growth factor (PDGF) and its receptors was studied by use of immunohistochemistry, followed by semiquantitative evaluation and multivariate analysis. In the syngeneically transplanted aortas, the expression of TGF-β1, PDGF, and the two PDGF receptors in the neointima increased significantly with the extent of cold ischemia time. Furthermore, there was a significant induction of the latent TGF-β binding protein in the neointima as well as TGF-β2 in the media, both correlating with the observation time after transplantation. In the allogeneic grafts, all examined proteins were already induced strongly 2 weeks after transplantation, even at the shortest ischemic period studied (1 hour). However, no positive correlation between growth factor expression and cold ischemia or observation time could be found. Double immunohistochemistry revealed that macrophages express PDGF and its receptors as well as TGF-β1. Smooth muscle cells express both types of PDGF receptors, and a few T cells express TGF-β1 as well as PDGF receptors. In summary, TGF-β and PDGF are induced by allogeneic as well as ischemic stimuli in transplanted aortas, suggesting a role in the pathogenesis of transplant arteriosclerosis and representing a potential target for therapeutic intervention.
Expression of Heparin-Binding Epidermal Growth Factor–Like Growth Factor in Neointimal Cells Induced by Balloon Injury in Rat Carotid Arteries
Authors: Igura Takumi , Kawata Sumio , Miyagawa Jun-ichiro , Inui Yoshiaki , Tamura Shinji , Fukuda Kazuto , Isozaki Koji , Yamamori Katsumi , Taniguchi Naoyuki , Higashiyama Shigeki , Matsuzawa Yuji
Published: June 2011

Balloon catheter injury of rat carotid arteries induces migration and proliferation of smooth muscle cells (SMCs), with subsequent neointimal formation. Several growth factors, such as platelet-derived growth factor and basic fibroblast growth factor, have been shown to be involved in this process, but the mechanisms that modulate the growth and/or migratory properties of SMCs remain unclear. In this study, we investigated whether heparin-binding epidermal growth factor–like growth factor (HB-EGF), which is known to be a potent SMC stimulator from in vitro study, is associated with the proliferative response of SMCs to arterial injury. Northern blot analysis showed that the transcript levels of HB-EGF increased rapidly approximately 12-fold within 2 hours after injury and declined by 2 days but remained 3-fold at 14 days. In situ hybridization analysis demonstrated that the transcript of HB-EGF remained strongly expressed in the neointima, especially near the luminal surface, at 14 days after injury. Immunohistochemical staining showed that HB-EGF protein was positive in the endothelium and only faintly visible in medial SMCs in uninjured vessels. In contrast, 2 days after injury, positive HB-EGF immunostaining was detected in the medial SMCs along the luminal surface. At 7 days, the neointimal SMCs exhibited strong immunostaining for HB-EGF, and at 14 days, they exhibited a gradient of HB-EGF expression with strong immunoreactivity in the most luminal cells. SMCs labeled with 5-bromo-2′-deoxyuridine in their nuclei showed strong immunostaining for HB-EGF protein. Furthermore, the epidermal growth factor receptor to which HB-EGF can bind was also immunostained positively in neointimal SMCs. These data suggest that HB-EGF may play an important role of the proliferation and migration of SMCs in the process of neointimal accumulation induced by arterial injury, probably in an autocrine, paracrine, and/or juxtacrine manner.
Ultrastructural Studies of Platelet Aggregates From Human Subjects Receiving Clopidogrel and From a Patient With an Inherited Defect of an ADP-Dependent Pathway of Platelet Activation
Authors: Humbert Michel , Nurden Paquita , Bihour Claude , Pasquet Jean-Max , Winckler Joëlle , Heilmann Eric , Savi Pierre , Herbert Jean-Marc , Kunicki Thomas J. , Nurden Alan T.
Published: June 2011

Our study investigated the effect of the antithrombotic drug clopidogrel (75 mg/d for 7 days) on the ultrastructure of platelet aggregates induced by ADP or 2-methylthio-ADP (2-MeS-ADP) in citrated platelet-rich plasma and examined the activation state of the GP IIb/IIIa complexes. Results were compared with those obtained for patient M.L., who has a congenital disorder characterized by a reduced and reversible platelet response to ADP. When untreated normal platelets were stimulated with high-dose ADP, electron microscopy revealed large and stable aggregates often surrounded by a layer of what appeared to be degranulated platelets. The reversible aggregates of platelets from subjects receiving clopidogrel or from patient M.L. did not show this layer. Electron microscopy showed that in both situations, the aggregates were composed of loosely bound platelets with few contact points. Immunogold labeling of ultrathin sections of Lowicryl-embedded aggregates formed by ADP or 2-MeS-ADP showed a much decreased platelet surface staining by (1) a polyclonal anti-fibrinogen antibody and (2) AP-6, a murine anti–ligand-induced binding site monoclonal antibody specific for GP IIb/IIIa complexes occupied with fibrinogen. Similar findings were seen after disaggregation, when many single platelets were present that showed no signs of secretion. Flow cytometry confirmed that the number of ligand-occupied GP IIb/IIIa complexes was much lower on platelets stimulated with ADP or 2-MeS-ADP after clopidogrel treatment. As expected from previous studies, ADP-induced platelet shape change and Ca
2+
influx were unaffected by clopidogrel. These results agree with the hypothesis that platelet activation by ADP is biphasic and highlight a receptor-induced activation pathway affected by clopidogrel (or congenitally impaired in patient M.L.) that is necessary for the full activation of GP IIb/IIIa and the formation of stable macroaggregates.
Importance of a Novel Oxidative Mechanism for Elimination of Intracellular Cholesterol in Humans
Authors: Lund Erik , Andersson Olof , Zhang Jie , Babiker Amir , Ahlborg Gunvor , Diczfalusy Ulf , Einarsson Kurt , Sjövall Jan , Björkhem Ingemar
Published: June 2011

Abstract
We have recently demonstrated that cultured human alveolar macrophages efficiently convert cholesterol into excretable 27-oxygenated products. We show here that increasing the intracellular concentration of cholesterol by a factor of 10 leads to about a twofold increase in the excretion of 27-oxygenated products from cultured macrophages. Inhibition of the sterol 27-hydroxylase caused a significant intracellular accumulation of cholesterol. A direct comparison was made between flux of cholesterol and 27-oxygenated products from macrophages preloaded with [4-
14
C]cholesterol. Under the specific conditions employed with fetal calf serum in the culture medium, the flux of 27-oxygenated products was about 10% of that of cholesterol. Since the sterol 27-hydroxylase, which converts cholesterol to 27-oxygenated products, is present in many cell types, we suggest that 27-oxygenation is a general mechanism for removal of intracellular cholesterol. To evaluate this hypothesis, we measured the net uptake by the human liver of circulating 27-oxygenated products, which was found to be about 20 mg/24 h. This uptake corresponds to ≈4% of the bile acid production, assuming quantitative conversion into bile acids. It is concluded that the 27-hydroxylase pathway is of significance for elimination of extrahepatic cholesterol.
Poland and United States Collaborative Study on Cardiovascular Epidemiology
Authors: Broda Grażyna , Davis Clarence E. , Pajak Andrzej , Williams O. Dale , Rywik Stefan L. , Baczyńska Ewa , Folsom Aaron R. , Szklo Moyses
Published: June 2011

Abstract
HDL cholesterol (HDL-C) levels are inversely related to coronary heart disease (CHD) risk, and HDL-C distributions vary among countries. Poland is one of the few developed countries in which CHD rates are increasing at the same time that US rates have been falling, but whether these differences are explained by differences in risk factors such as HDL-C has not been determined. To examine this possibility, levels of HDL-C and its subfractions were compared in US and Polish urban and rural men and women aged 45 to 64 years. Age-adjusted HDL-C means were 0.20 mmol/L higher in urban Polish men and 0.37 mmol/L higher in rural Polish men than in their US counterparts (
P
<.0001); means in urban Polish women were 0.06 mmol/L higher (
P
<.05) and in rural Polish women 0.09 mmol/L higher (
P
<.001) than in their US counterparts. Adjustment for age, education, alcohol intake, smoking, BMI, heart rate, and menopause status (in women) had little effect on differences. Means of HDL
2
and HDL
3
levels showed similar between-country differences, although differences were minimal for HDL
2
in urban men and women, and HDL
3
means did not differ between rural women. BMI was inversely related to HDL-C and both subfractions in all gender-country-site strata (
P
<.001), and alcohol was directly related to HDL-C (
P
<.001) in all strata except Polish women. Cigarette smoking was negatively related to HDL-C and both subfractions in all US samples except HDL
2
in urban men, whereas in Polish samples, significant associations were found only in urban women for HDL-C and in rural and urban women for HDL
3
. Age, heart rate, and education showed inconsistent or no association with HDL-C and its subfractions in either country. This profile of HDL-C and its subfractions in Polish samples contrasts sharply with the opposite trend in CHD mortality rates, which suggests either that other risk factors may account for the trends or that the relationship between HDL-C and CHD may differ between the two countries.
Evidence for a Synergistic Effect of Calcium Channel Blockers With Lipid-Lowering Therapy in Retarding Progression of Coronary Atherosclerosis in Symptomatic Patients With Normal to Moderately Raised Cholesterol Levels
Authors: Jukema J. Wouter , Zwinderman Aeilko H. , van Boven Ad J. , Reiber Johan H.C. , Van der Laarse Arnoud , Lie Kong I. , Bruschke Albert V.G.
Published: June 2011

Abstract
To date, lipid-lowering therapy appears to be the most effective medical intervention to retard progression of coronary atherosclerosis. In spite of promising experimental results, clinical trials completed so far have failed to demonstrate that calcium channel blockers (CCBs) alone influence the evolution of established coronary atherosclerosis. To assess whether the two therapies may have an additive or synergistic beneficial effect on human atherosclerosis, we reviewed in this regard the data of the angiographic Regression Growth Evaluation Statin Study (REGRESS) trial. REGRESS was designed to determine the effect of lipid-lowering therapy with pravastatin in symptomatic patients with normal to moderately raised cholesterol levels. Angiographically, with respect to the minimum obstruction diameter, in the pravastatin group, patients had on average 0.05 mm (95% confidence interval [CI]: 0.01-0.09) less progression if cotreated with CCBs compared with no CCB cotreatment, whereas in the placebo (no pravastatin) group, no effect of CCB treatment was observed (interaction test for differential effect of CCB treatment in patients with pravastatin compared with patients receiving placebo:
P
=.0016). With respect to the mean segment diameter, similar although not significant (
P
=.33) results were found. With respect to new lesion formation, in the pravastatin group, there were 50% (CI: 25-83) fewer patients with new angiographic lesions if cotreated with CCBs compared with no CCB cotreatment, whereas in the placebo (no pravastatin) group, no significant effect of CCB treatment was observed (interaction test:
P
=.0026). No beneficial effects of CCB treatment on clinical events were observed. Although the REGRESS trial was not designed to evaluate combination therapy, the results suggest strongly that addition of CCBs to 3-hydroxy-3-methylglutaryl–coenzyme reductase inhibitor therapy (pravastatin) acts synergistically in retarding the progression of established coronary atherosclerosis.
Increased Cholesteryl Ester Transfer Activity in Plasma From Analbuminemic Patients
Authors: Braschi Sylvie , Lagrost Laurent , Florentin Emmanuel , Martin Claude , Athias Anne , Gambert Philippe , Krempf Michel , Lallemant Christian , Jacotot Bernard
Published: June 2011

AbstractHypercholesterolemia associated with analbuminemia, an inherited disease manifesting low plasma albumin concentration, is characterized by enhanced LDL cholesterol levels and reduced HDL cholesterol levels. In addition, compared with normal counterparts, the esterified cholesterol:triglyceride ratio tends to be higher in analbuminemic apoB-containing lipoproteins and lower in analbuminemic HDL. The aim of the present study was to investigate the mechanism that may account for the association of a hypoalbuminemic state with alterations in the concentration and composition of plasma lipoprotein fractions. To this end, endogenous cholesterol esterification activity, phospholipid transfer activity, and cholesteryl ester transfer activity were measured in total plasma from three analbuminemic patients and five control subjects. Whereas endogenous cholesterol esterification and phospholipid transfer rates were not significantly affected in analbuminemia, the transfer of radiolabeled cholesteryl esters from HDL toward apoB-containing lipoproteins was constantly higher in analbuminemic plasmas than in normal control plasma (473.6±107.3%·h−1·mL−1versus 227.5±84.0%·h−1·mL−1, respectively;P=.036). The rise in cholesteryl ester transfer protein (CETP) activity in analbuminemic plasma was due to a significant increase in the transfer of radiolabeled cholesteryl esters toward LDL but not toward the triglyceride-rich lipoproteins. The CETP mass was higher in analbuminemic patients than in control subjects, but the difference did not reach the significance level (5.18±0.82 mg/L versus 3.13±1.19 mg/L, respectively;P=.07). Since abnormally elevated nonesterified fatty acid (NEFA) levels were shown to be associated with analbuminemic lipoproteins, mostly LDL, the direct role of lipoprotein-bound NEFA in enhancing CETP activity was suspected. In support of this view, supplementation of total plasmas with fatty acid–poor albumin was shown to reduce CETP activity to a significantly greater extent in analbuminemic plasmas than in normal control plasma. It is concluded that hyperlipidemia associated with the hypoalbuminemic state can relate, at least in part, to the combined effect of CETP and NEFA in promoting the transfer of cholesteryl esters from the antiatherogenic HDL toward the proatherogenic apoB-containing lipoproteins.
Thrombin-Induced Increase in Endothelial Permeability Is Associated With Changes in Cell-to-Cell Junction Organization
Authors: Rabiet Marie-Josèphe , Plantier Jean-Luc , Rival Yves , Genoux Yolande , Lampugnani Maria-Grazia , Dejana Elisabetta
Published: June 2011

Abstract
Thrombin increases endothelial permeability in a rapid and reversible way. This effect requires the catalytic activity of the enzyme and thrombin receptor engagement. Endothelial cell permeability is mostly regulated by intercellular junction organization. In the present study, we investigated whether opening of intercellular gaps after thrombin treatment could be related to changes in adherence-junction molecular organization. By immunofluorescence analysis, we found that thrombin stimulation of endothelial cells caused a marked alteration of the distribution of vascular endothelial (VE)-cadherin and of the associated catenins. These molecules, which are strictly localized at intercellular boundaries in confluent resting cells, were absent in the areas of intercellular retraction. Immunoprecipitation analysis indicated that thrombin disrupted the VE-cadherin/catenin complex. This effect was reversible and correlated with the increase in endothelial permeability. The use of a protein kinase C inhibitor (calphostin C) blocked both thrombin-induced permeability and disassembly of adherence-junction components. We propose that thrombin’s effect on endothelial cell junction organization is an important determinant in the increase in endothelial permeability induced by this agent.
Oxidized Lipids in the Diet Accelerate the Development of Fatty Streaks in Cholesterol-Fed Rabbits
Authors: Staprãns Ilona , Rapp Joseph H. , Pan Xian-Mang , Hardman David A. , Feingold Kenneth R.
Published: June 2011

Abstract
Studies have indicated that oxidized lipoproteins may play a role in atherosclerosis. We have recently demonstrated that the levels of oxidized lipoproteins in the circulation can be directly correlated to the quantity of oxidized lipids in the diet. The present study tested the hypothesis that dietary oxidized lipids accelerate the development of atherosclerosis. For 12 to 14 weeks, 36 male New Zealand White rabbits were fed a low-cholesterol (0.25%) diet containing either 5% unoxidized corn oil (control diet) or 5% oxidized corn oil (oxidized-lipid diet). Serum cholesterol levels increased to a similar extent in both groups, with the majority of the cholesterol in the β-migrating very low density lipoprotein (β-VLDL) fraction. β-VLDL from control animals contained 3.86±0.57 versus 9.07±2.14 nmol conjugated dienes per μmol cholesterol (
P
<.05) in rabbits fed the oxidized-lipid diet. No difference in oxidized lipid levels was detected in LDL. Most important, feeding a diet rich in oxidized lipid resulted in a 100% increase in fatty streak lesions in the aorta. Additionally, rabbits that were fed the oxidized-lipid diet had a >100% increase in total cholesterol in the pulmonary artery that was primarily due to an increase in cholesteryl ester. Oxidized lipids are frequently present in the typical US diet, and our results suggest that consumption of these foods may be an important risk factor for atherosclerosis.
βig-h3, a Transforming Growth Factor–β–Inducible Gene, Is Overexpressed in Atherosclerotic and Restenotic Human Vascular Lesions
Authors: O’Brien Edward R. , Bennett Kelly L. , Garvin Michael R. , Zderic Ted W. , Hinohara Tomoaki , Simpson John B. , Kimura Takeshi , Nobuyoshi Masakiyo , Mizgala Henry , Purchio Anthony , Schwartz Stephen M.
Published: June 2011

Abstract
Transforming growth factor–β (TGF-β) plays an important role in vascular lesion formation and possibly the renarrowing process (“restenosis”) that occurs after balloon angioplasty. Secreted in a latent form by most cells, TGF-β requires enzymatic conversion before it is biologically active. TGF-β–inducible gene h3 (βig-h3) is a novel molecule that is induced when cells are treated with TGF-β1. This study examined the expression of βig-h3 in normal and diseased human vascular tissue. To determine the expression pattern of βig-h3 in human arteries, immunocytochemistry was performed on tissue sections from (1) normal internal mammary arteries, (2) the proximal left anterior descending coronary artery (with minimal intimal thickening) of 15 patients aged 18 to 40 years, (3) primary and restenotic coronary lesions from 7 patients, and (4) fresh directional atherectomy tissue from 11 patients. A polyclonal antibody consistently immunodetected βig-h3 protein in endothelial cells of all vascular tissue. In normal coronary arteries of young individuals, βig-h3 protein was absent from the intima and media but was found in the subendothelial smooth muscle cells of some arteries with modest intimal thickening. In diseased arteries βig-h3 protein was more abundant in the intima than the media. Restenotic coronary lesions tended to show higher levels of immunodetectable βig-h3 protein, especially in areas of dense fibrous connective tissue. βig-h3 protein was immunodetected in the cytoplasm of plaque macrophages as well as smooth muscle and endothelial cells. By using in situ hybridization on fresh directional atherectomy specimens, we found βig-h3 mRNA to be overexpressed by plaque macrophages and smooth muscle cells. Nondiseased human internal mammary arteries also expressed βig-h3 mRNA in endothelial cells but not in the smooth muscle cells of the normal intima and media. These results document the expression of βig-h3 in diseased human arterial tissue and support the hypothesis that active TGF-β plays a role in atherogenesis and restenosis.
Agglutination of Isolated Platelet Membranes
Authors: Gawaz Meinrad , Ott Ilka , Reininger Armin J. , Heinzmann Ulrich , Neumann Franz-Josef
Published: June 2011

Abstract
Platelet membrane glycoproteins play a central role in platelet aggregation and thus in primary hemostasis. To investigate mechanisms of platelet-platelet interaction in the absence of cellular activation events, we studied immunological and functional aspects of isolated platelet membranes. Platelet membranes contained significant amounts of the inducible fibrinogen receptor, glycoprotein (GP) IIb-IIIa, which exposes conformation-dependent LIBS1 and PMI-1 epitopes in response to fibrinogen-mimetic peptides GRGDSP and HHLGGAKQAGDV. In the presence of soluble fibrinogen, membrane-coated latex beads showed Ca
2+
-dependent agglutination that could be partially inhibited by GRGDSP but not by the biologically inactive peptide GRGESP. Thrombospondin enhanced agglutination of membrane-coated beads, which could be inhibited by polyvalent anti-thrombospondin Fab fragments and anti-thrombospondin monoclonal antibody MA-II. Mg
2+
inhibited both GPIIb-IIIa– and thrombospondin-mediated agglutination of membranes in a dose-dependent manner. The results of the present study indicate that isolated platelet membranes are a useful tool to study regulation of GPIIb-IIIa– and thrombospondin-mediated platelet-platelet interaction.
A Quantitative Immunoassay for the Lysine-Binding Function of Lipoprotein(a)
Authors: Hoover-Plow Jane L. , Boonmark Nataya , Skocir Pamela , Lawn Richard , Plow Edward F.
Published: June 2011

Abstract
Apo(a), the unique apoprotein of lipoprotein(a) (Lp[a]), can express lysine-binding site(s) (LBS). However, the LBS activity of Lp(a) is variable, and this heterogeneity may influence its pathogenetic properties. An LBS-Lp(a) immunoassay has been developed to quantitatively assess the LBS function of Lp(a). Lp(a) within a sample is captured with an immobilized monoclonal antibody specific for apo(a), and the captured Lp(a) is reacted with an antibody specific for functional LBS. The binding of this LBS-specific antibody is then quantified by using an alkaline phosphatase–conjugated disclosing antibody. The critical LBS-specific antibody was raised to kringle 4 of plasminogen. When applied to plasma samples, the LBS activity of Lp(a) ranged from 0% to 100% of an isolated reference Lp(a); the signal corresponded to the percent retention of Lp(a) on a lysine-Sepharose column but did not correlate well with total Lp(a) levels in plasma. Mutation of residues in the putative LBS in the carboxy-terminal kringle 4 repeat (K4-37) in an eight-kringle apo(a) construct resulted in marked but not complete loss of activity in the LBS-Lp(a) immunoassay. These data suggest that this kringle is the major but not the sole source of LBS activity in apo(a). The LBS-Lp(a) immunoassay should prove to be a useful tool in establishing the role of the LBS in the pathogenicity of Lp(a).
Isolation and Characterization of Tissue-Type Plasminogen Activator–Binding Proteoglycans From Human Umbilical Vein Endothelial Cells
Authors: Böhm Thomas , Geiger Margarethe , Binder Bernd R.
Published: June 2011

Abstract
We analyzed the tissue-type plasminogen activator (TPA)–binding proteoglycans (PGs) on human umbilical vein endothelial cells (HUVECs), which were metabolically labeled with [
35
S]Na
2
SO
4
. Cell extracts were then prepared and subjected to affinity chromatography on diisopropyl fluorophosphate (DFP)–inactivated TPA–Sepharose 4B. Approximately 6% of the incorporated
35
S radioactivity bound to DFP-treated TPA–Sepharose 4B and was eluted with 2 mol/L NaCl. In addition to NaCl, heparin, arginine, and lysine but not glycine, ε-amino-
n
-caproic acid, or aspartic acid inhibited this binding and eluted the bound
35
S radioactivity. Urea-containing polyacrylamide gel electrophoresis of the eluted material consistently revealed two main signals of
35
S radioactivity (one with an
M
r
between 600 000 and 750 000 [PGA] and the other with an
M
r
between 120 000 and 180 000 [PGC]). Occasionally a less intense signal with an
M
r
between 340 000 and 440 000 (PGB) was seen. Heparitinase treatment markedly decreased the intensities of both
35
S signals (PGA and PGB), and chondroitinases AC and ABC abolished the
35
S signal of PGC, indicating that most of the HUVEC-incorporated radioactivity with an affinity for TPA could be attributed to heparan sulfate– and chondroitin sulfate–like structures. Reductive elimination, which was performed to separate the possible glycosaminoglycan moieties from the core proteins, confirmed the PG-like nature of this material and again revealed heparan sulfate and chondroitin sulfate as the major glycosaminoglycan components. We therefore conclude that HUVECs synthesize TPA-binding, heparan sulfate– and chondroitin sulfate–containing PGs. In vivo, similar PGs may play a role in TPA binding to endothelial cells and thereby possibly influence TPA activity and/or provide an intravascular storage pool of TPA.
Endothelium-Dependent and -Independent Vasodilation of Large Arteries in Normoalbuminuric Insulin-Dependent Diabetes Mellitus
Authors: Lambert Jan , Aarsen Mieke , Donker Ab J.M. , Stehouwer Coen D.A.
Published: June 2011

Abstract
Vascular complications in diabetes mellitus are associated with endothelial dysfunction. Whether endothelium-dependent vasodilation is impaired in normoalbuminuric patients with insulin-dependent diabetes mellitus (IDDM) is controversial. Using a noninvasive echo-Doppler method, we investigated endothelium-dependent and endothelium-independent vasodilation in the brachial artery of IDDM patients. There were 52 normoalbuminuric and normotensive patients with IDDM (aged 31.9±9.8 years; diabetes duration, 14.9±7.9 years; glycated hemoglobin, 7.9±1.2%) and 52 healthy control group (C) subjects comparable for age and sex studied. Brachial artery diameter was measured at baseline, during postocclusion reactive hyperemia (flow-mediated, endothelium-dependent dilation [FMD]), and after 400 μg glyceryl trinitrate (GTN) sublingually (endothelium-independent vasodilation). Vasodilation was expressed as the percentage change relative to the baseline diameter. Baseline flow and blood pressure were similar for IDDM patients and C. Baseline vessel diameter was slightly larger in IDDM patients (3.10±0.52 mm) compared with C (2.89±0.55 mm,
P
=.05). FMD in IDDM patients was decreased (12.0±9.1% versus 15.7±9.5% in C,
P
=.046), as was GTN-induced vasodilation (14.9±8.2% versus 18.3±8.5% in C,
P
=.045). After correction for the difference in baseline diameter, FMD and GTN-induced dilation were not different between the groups. GTN-induced vasodilation decreased slightly with increasing diabetes duration. There was no relation between the vasodilatory responses and HbA1c. In normoalbuminuric IDDM patients, endothelium-dependent as well as endothelium-independent vasodilation are normal when the difference in baseline diameter is taken into account.
Contribution of an In Vivo Oxidized LDL to LDL Oxidation and Its Association With Dense LDL Subpopulations
Authors: Sevanian Alex , Hwang Juliana , Hodis Howard , Cazzolato Giuseppe , Avogaro Pietro , Bittolo-Bon Gabriele
Published: June 2011

Abstract
Oxidative modification of LDL is thought to be a radical-mediated process involving lipid peroxides. The small dense LDL subpopulations are particularly susceptible to oxidation, and individuals with high proportions of dense LDL are at a greater risk for atherosclerosis. An oxidatively modified plasma LDL, referred to as LDL
−
, is found largely among the dense LDL fractions. LDL
−
and dense LDL particles also contain much greater amounts of lipid peroxides compared with total LDL or the more buoyant LDL fractions. The content of LDL
−
in dense LDL particles appears to be related to copper- or heme-induced oxidative susceptibility, which may be attributable to peroxide levels. The rate of lipid peroxidation during the antioxidant-protected phase (lag period) and the length of the antioxidant-protected phase (lag time) are correlated with the LDL
−
content of total LDL. Once LDL oxidation enters the propagation phase, there is no relationship to the initial LDL
−
content or total LDL lipid peroxide or vitamin E levels. Beyond a threshold LDL
−
content of ≈2%, there is a significant increase in the oxidative susceptibility of nLDL particles (ie, purified LDL that is free of LDL
−
), and this susceptibility becomes more pronounced as the LDL
−
content increases. nLDL is resistant to copper- or heme-induced oxidation. The oxidative susceptibility is not influenced by vitamin E content in LDL but is strongly inhibited by ascorbic acid in the medium. Involvement of LDL
−
-associated peroxides during the stimulated oxidation of LDL is suggested by the inhibition of nLDL oxidation when LDL
−
is treated with ebselen prior to its addition to nLDL. Populations of LDL enriched with LDL
−
appear to contain peroxides at levels approaching the threshold required for progressive radical propagation reactions. We postulate that elevated LDL
−
may constitute a pro-oxidant state that facilitates oxidative reactions in vascular components.
Antithrombin and Atherosclerosis in the Rotterdam Study
Authors: van der Bom J.G. , Bots M.L. , van Vliet H.H.D.M. , Pols H.A.P. , Hofman A. , Grobbee D.E.
Published: June 2011

Antithrombin is a potent inhibitor of thrombotic tendency. Whether atherosclerotic disease is associated with high or low antithrombin is unclear. Studies of the relation between antithrombin and presence of arterial disease have shown contrasting results. In the Rotterdam Study, a single-center, population-based cohort study of 7983 subjects aged 55 years and older, the association between atherosclerosis and antithrombin was evaluated. The ratio of ankle to arm blood pressure is a graded marker for atherosclerosis and provides the opportunity to investigate nonlinear associations. In the first 1427 participants of the Rotterdam Study who did not use anticoagulants, both antithrombin and the ratio of ankle to arm blood pressure were measured. In men the association between the two was quadratic: antithrombin activity was increased in men with moderate peripheral arterial atherosclerosis compared with those without, and in men with more severe atherosclerosis it was decreased. In women the association was linear: a decreased ratio of ankle to arm pressure was associated with increased antithrombin activity. These associations were independent of smoking, body mass index, serum lipids, fibrinogen, and factor VIIc. We propose that antithrombin activity rises in response to increased risk of cardiovascular disease and also in response to the presence of atherosclerosis, whereas antithrombin may decrease with increasing severity of the atherosclerotic process in men. This may explain the contrasting results found in previous studies. Changes in antithrombin over time might be useful in predicting the risk of cardiovascular disease and progression.