bluuebunny/crossref_metadata_2025 huggingface dataset:
The endothelium during cuff-induced neointima formation in the rabbit carotid artery.
Authors: Kockx M M , De Meyer G R , Andries L J , Bult H , Jacob W A , Herman A G
Published: June 2011

Intimal thickening in human arteries is considered as a site of predilection for atherosclerosis. The placement of a flexible, physically nonconstrictive, silicone cuff around the rabbit carotid artery induced a neointima composed of smooth muscle cells (SMCs) within 14 days. To investigate possible alterations of the endothelial cells (ECs) during neointima formation, their morphology was examined with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal microscopy. In the early postoperative period (6 hours), both cuffed and sham-operated arteries demonstrated small foci (5 to 200 microns) of denudation, presumably as a consequence of the manipulation. Within 24 hours the luminal surface of the cuffed and sham-operated arteries was completely covered with endothelium, which remained continuous throughout the study. However, after 1 week the ECs of the cuffed arteries contained a pronounced rough endoplasmic reticulum. From 6 hours until 3 days, polymorphonuclear leukocytes infiltrated the cuffed but not the sham-operated arteries from the lumen. Subendothelial SMC accumulation in the cuffed arteries began after this time period. At day 14 a full-blown neointima composed of longitudinally oriented SMCs had formed in the cuffed arteries. The sham-operated arteries did not develop a neointima. During neointima formation immunoreactivity for von Willebrand factor (vWf) increased in the ECs, and vWf was deposited in the extracellular spaces of the neointima. At day 14 the area of vWf deposits correlated positively with the area of the neointima (r = .73, P < .001). In subsequent weeks, the intimal area did not increase, and vWf deposits vanished from the neointimal matrix. The endothelium of the sham-operated arteries showed no change in vWf immunoreactivity compared with untreated arteries throughout the study. The altered ultrastructural morphology of the ECs and the concurrent vWf deposition in cuffed but not in sham-operated arteries point to alterations in EC function during the development of the neointima. The vWf secretion could possibly lead to increased adhesiveness of the extracellular matrix for the ECs as well as modulate neointima formation.
Effects of simvastatin on apoB metabolism and LDL subfraction distribution.
Authors: Gaw A , Packard C J , Murray E F , Lindsay G M , Griffin B A , Caslake M J , Vallance B D , Lorimer A R , Shepherd J
Published: June 2011

Seven moderately hypercholesterolemic subjects were studied before and after 10 weeks of simvastatin therapy (20 mg/day). Therapy reduced low density lipoprotein (LDL) cholesterol by 39% (p < 0.001), whereas high density lipoprotein and very low density lipoprotein (VLDL) cholesterol were unchanged. Apolipoprotein (apo) B-containing lipoproteins were divided into VLDL1 (Sf 60-400), VLDL2 (Sf 20-60), intermediate density lipoprotein (IDL) (Sf 12-20), and LDL (Sf 0-12), and metabolic changes were sought in dual-tracer VLDL1 and VLDL2 turnover studies. VLDL1 apoB pool size was unaltered by therapy, as were its rates of synthesis, catabolism, and delipidation to VLDL2. Similarly, the VLDL2 apoB pool size was unchanged, but its metabolic fate was altered. The IDL pool size fell significantly (27%, p < 0.01) due entirely to an increased fractional catabolism of the lipoprotein. In our subjects, the circulating mass of LDL apoB decreased (49%, p < 0.01) primarily due to a reduction in its synthesis. Before therapy, 30% of the apoB entering the delipidation cascade in these hyperlipidemic subjects was converted to LDL. On therapy the input remained the same, but direct catabolism from VLDL2 and IDL was increased (p < 0.05), and as a result only 16% eventually appeared in LDL. These kinetic changes were associated with a fall in particle cholesteryl ester content throughout the delipidation cascade. We also observed a link between LDL kinetics and its subfraction distribution. Simvastatin influences the metabolism of LDL, IDL, and VLDL2 but not VLDL1.
High macrophage lipoprotein lipase expression and secretion are associated in inbred murine strains with susceptibility to atherosclerosis.
Authors: Renier G , Skamene E , DeSanctis J B , Radzioch D
Published: June 2011

To test the possibility that variations in macrophage lipoprotein lipase (LPL) secretion may constitute one of the hereditary components of atherosclerosis, we evaluated LPL gene expression and secretion in macrophages harvested from inbred mouse strains differing in their susceptibility to the diet-induced development of atherosclerosis. Inflammatory peritoneal macrophages harvested from atherosclerosis-susceptible C57BL/6J mice showed twofold to threefold higher basal LPL mass, activity, and mRNA levels than those isolated from atherosclerosis-resistant C3H/HeN mice. We determined LPL secretion and gene expression in the susceptible C57BL/6J (B), resistant A/J (A), and A x B/B x A recombinant inbred strains of mice typed as atherosclerosis resistant (A-like) or atherosclerosis susceptible (B-like). Macrophage LPL secretion and mRNA expression were twofold higher in the susceptible C57BL/6J (B) mice than in the resistant A/J (A) mice. Significantly higher LPL secretion, activity, and gene expression were found in recombinant inbred mouse strains that typed B-like than in those typed A-like. These results indicate that susceptibility to atherosclerosis is associated in inbred mouse strains with high LPL secretion and mRNA levels, whereas lower LPL secretion and mRNA expression are observed in atherosclerosis-resistant mice. These observations suggest a contributive role for LPL in the development of atherosclerosis.
An atherogenic diet rapidly induces VCAM-1, a cytokine-regulatable mononuclear leukocyte adhesion molecule, in rabbit aortic endothelium.
Authors: Li H , Cybulsky M I , Gimbrone M A , Libby P
Published: June 2011

Accumulation of monocyte-derived foam cells in focal areas of the arterial intima is a key step in early atherogenesis. We investigated the expression of vascular cell adhesion molecule-1 (VCAM-1), a mononuclear leukocyte adhesion molecule, in the arterial endothelium during the early phases of diet-induced atherogenesis in rabbits in vivo and the regulation of VCAM-1 expression by cytokines in rabbit aortic organoid cultures in vitro. Rabbits were fed either an atherogenic diet (containing 0.3% cholesterol, 9% coconut oil, and 1% corn oil) or an isocaloric control diet (10% corn oil) for 4 days or 1, 3, 6, or 13 weeks. The endothelium in the ascending aorta focally expressed VCAM-1 after only 1 week on the atherogenic diet but before the first appearance of intimal macrophages, as judged by immunohistochemical staining of serial sections. The rabbits that consumed the atherogenic diet for 3 weeks or longer developed lesions in the intima composed of macrophages bearing class II major histocompatibility antigen (MHC-II). Endothelial cells continued to focally express VCAM-1 at sites of MHC-II-positive intimal macrophages for up to 13 weeks. The ascending aortas of control rabbits lacked VCAM-1 or MHC-II-positive endothelium or macrophages at all times studied. These observations demonstrate the focal activation of arterial endothelium as early as 7 days after initiation of an atherogenic diet (at serum cholesterol levels of 308 +/- 57 mg/dl).(ABSTRACT TRUNCATED AT 250 WORDS)
Glutamine/histidine polymorphism in apo A-IV affects plasma concentrations of lipoprotein(a) and fibrin split products in coronary heart disease patients.
Authors: von Eckardstein A , Heinrich J , Funke H , Schulte H , Schönfeld R , Köhler E , Steinmetz A , Assmann G
Published: June 2011

A glutamine/histidine polymorphism at residue 360 in apolipoprotein (apo) A-IV that generates two electrophoretically detectable isoforms, apo A-IV-1 and apo A-IV-2, affects the plasma concentration of lipoprotein(a) (Lp[a]) in a healthy population. To verify this unexpected association we analyzed the effect of the apo A-IV polymorphism on Lp(a) serum concentrations in 275 male coronary heart disease patients. Allele frequencies of apo A-IV-1 and apo A-IV-2 were 0.917 and 0.083, respectively. In addition, apo A-IV-1/2 heterozygotes showed a 30% lower geometric mean concentration of Lp(a) than apo A-IV-1/1 homozygotes in this study. The relative frequency of Lp(a) concentrations > 20 mg/dl was significantly increased by a factor of 2.25 in apo A-IV-1/1 homozygotes. Other lipid parameters were not significantly affected by this apo A-IV polymorphism. Because of the relations between Lp(a) and the fibrinolytic system, we also analyzed the effect of the apo A-IV polymorphism on hemostatic variables. Apo A-IV-1/2 heterozygosity was associated with a 70% higher geometric mean plasma concentration of D-dimer, i.e., proteolytic fragments of cross-linked fibrin. Plasma concentrations of prothrombin fragments F1 + F2, fibrinogen, plasminogen, and plasminogen activator inhibitor-1 were unaffected. In conclusion, our results indicate a hitherto unappreciated role of the apo A-IV gene or a closely linked locus for the regulation of Lp(a) metabolism and hemostasis and also possibly for atherosclerosis and thrombosis.
Cholesteryl ester loading of mouse peritoneal macrophages is associated with changes in the expression or modification of specific cellular proteins, including increase in an alpha-enolase isoform.
Authors: Bottalico L A , Kendrick N C , Keller A , Li Y , Tabas I
Published: June 2011

This report explores the hypothesis that massive cholesteryl ester (CE) accumulation in macrophages, such as that occurring in atheroma foam cells, results in changes in the expression or modification of specific cellular proteins. Two-dimensional (2-D) gel electrophoretic patterns of metabolically labeled cellular proteins from mouse peritoneal macrophages that were loaded with CE (through incubation with acetylated low density lipoprotein [acetyl-LDL] for 4 days) were compared with those of control macrophages. Densitometric analysis of 2-D gel autoradiograms from the cell lysates revealed statistically significant changes in seven cellular proteins (five decreases and two increases). The changes in protein expression (foam cell versus control) ranged from a 458 +/- 164% (p < 0.001) increase to a 35 +/- 34% (p < 0.001) decrease (n = 11). Incubation of macrophages with beta-very low density lipoprotein, which also increased the CE content of macrophages (albeit to a lesser extent than acetyl-LDL), resulted in changes in five of the seven proteins. In contrast, incubation of cells with LDL, fucoidan, or latex beads, none of which caused CE accumulation, did not lead to significant changes in four of these five proteins. One of these four proteins, which increased fourfold to fivefold in foam cells (M(r) = 49,000; isoelectric point of 6.8), was purified by preparative 2-D gel electrophoresis. Internal amino acid sequence of cyanogen bromide fragments of this protein as well as Western blot analysis identified this protein as an isoform of alpha-enolase. The increased expression of this alpha-enolase isoform, which was seen as early as day 2 of acetyl-LDL incubation of the macrophages, was diminished by including an inhibitor of cholesterol esterification during the acetyl-LDL incubation period. In conclusion, macrophage foam cell formation is associated with distinct changes in protein expression, including a marked increase in an isoform of alpha-enolase, suggesting a specific biological adaptation to CE loading.
Gemfibrozil reduces postprandial lipemia in non-insulin-dependent diabetes mellitus.
Authors: Syvänne M , Vuorinen-Markkola H , Hilden H , Taskinen M R
Published: June 2011

The effect of gemfibrozil on postprandial lipoprotein metabolism was investigated in a 12-week, randomized, double-blind, placebo-controlled trial in 20 non-insulin-dependent diabetic patients with moderate hypertriglyceridemia. The patients were given a meal containing 78 g of fat and 345,000 units of vitamin A to label chylomicrons and their remnants. Plasma obtained at various times during the fat-load test was separated into six fractions by gradient-density ultracentrifugation. Gemfibrozil reduced the postprandial triglyceride response, measured as the area under the time-dependent concentration curve, on average by 32% in whole plasma, by 38% in the Svedberg flotation unit (Sf) 1,100-3,200 chylomicron fraction, by 36% in Sf 400-1,100 chylomicrons, and by 38% in the Sf 60-400 lipoproteins. Retinyl palmitate, a measure of intestinally derived particles, was reduced in plasma by 34%, in Sf 1,100-3,200 by 46%, in Sf 400-1,100 by 44%, and in Sf 60-400 by 37%. All these reductions were significant in comparison with the placebo group. Particles with Sf < 60 were not significantly affected. In contrast to earlier observations in healthy subjects, no significant negative correlations existed between postprandial lipemia and high density lipoprotein cholesterol or the postheparin lipoprotein lipase activity. The reduction of the potentially atherogenic chylomicron remnants may decrease the risk of atherosclerosis in non-insulin-dependent diabetes mellitus, a hypothesis that awaits testing in prospective studies.
Relation of vessel wall shear stress to atherosclerosis progression in human coronary arteries.
Authors: Gibson C M , Diaz L , Kandarpa K , Sacks F M , Pasternak R C , Sandor T , Feldman C , Stone P H
Published: June 2011

The purpose of this study was to determine the relation between vessel wall shear stress and the rate of atherosclerosis progression. Quantitative angiography was used to calculate the change in coronary arterial diameter over 3.0 years in patients enrolled in the Harvard Atherosclerosis Reversibility Project pilot study (n = 20 arterial segments). Vessel wall shear stress was calculated by means of a validated finite-difference model of the Navier-Stokes' equation that assumes a coronary flow rate of 8 ml/sec. The correlation between vessel wall shear stress and the change in arterial diameter at multiple points (mean, 70) along the length of the artery was then calculated for each of the 20 segments with a focal stenosis. In 15 of the 20 arterial segments there was a significant correlation (p < 0.05) between low shear stress and an increased rate of atherosclerosis progression. A Fisher's z transformation was then used to combine the correlation coefficients from all 20 segments. Low shear stress was significantly correlated (z = 0.37 +/- 0.00074, p < 0.0001) with an increased rate of atherosclerosis progression. This serial quantitative evaluation of human coronary arteries is consistent with previous data that have suggested that low shear stress promotes atherosclerosis progression. Variations in local vessel wall shear stress may explain the previously reported near-independent rate of atherosclerosis progression in multiple lesions within the same patient despite exposure to the same circulating lipoprotein values and systemic hemodynamics.
Lipoproteins in familial dysbetalipoproteinemia. Variation of serum cholesterol level associated with VLDL concentration.
Authors: Zhao S P , Smelt A H , Leuven J A , van den Maagdenberg A M , van der Laarse A , van 't Hooft F M
Published: June 2011

Patients with familial dysbetalipoproteinemia (FD) associated with the apo E2/2 phenotype exhibit a marked interindividual variability in serum cholesterol and triglyceride concentrations. It has been proposed that this variability is due to a combination of the apo E2/2 phenotype and additional genetic factors implicated in diseases like familial hypercholesterolemia, familial combined hyperlipoproteinemia, and familial hypertriglyceridemia. To further explore the nature of this variability, the lipoprotein profiles of 17 patients with FD associated with the apo E2/2 phenotype were analyzed by a density-gradient ultracentrifugation technique and by 2-16% polyacrylamide gel electrophoresis. It was found that all patients with FD were characterized by 1) markedly increased cholesterol concentrations of large very low density lipoprotein (VLDL) (VLDL1) (2.98 +/- 3.08 versus 0.08 +/- 0.03 mmol/L), small VLDL (VLDL2) (4.68 +/- 1.93 versus 0.27 +/- 0.13 mmol/L), and intermediate density lipoprotein (IDL) (2.25 +/- 0.72 versus 0.39 +/- 0.16 mmol/L); 2) decreased low density lipoprotein (LDL) cholesterol level (1.84 +/- 0.54 versus 3.36 +/- 0.53 mmol/L); and 3) altered composition (enrichment by cholesteryl ester) of VLDL1 and VLDL2 compared with normolipidemic control subjects. The cholesterol levels of IDL and LDL showed minor interindividual variabilities and were not correlated with serum cholesterol and triglyceride levels. The compositions of VLDL1 and VLDL2 were independent of the concentrations of lipids in serum. However, the cholesterol concentrations of VLDL1 and VLDL2 showed considerable interindividual variabilities and were positively correlated with the serum cholesterol concentration (r = 0.84 and r = 0.95, respectively, both p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Tumor necrosis factor-alpha stimulates ICAM-1 expression in human vascular smooth muscle cells.
Authors: Couffinhal T , Duplàa C , Labat L , Lamaziere J M , Moreau C , Printseva O , Bonnet J
Published: June 2011

Human atherosclerotic plaques contain numerous smooth muscle cells (SMCs) that express intercellular adhesion molecule-1 (ICAM-1). Expression of ICAM-1 in different cells is known to be regulated by tumor necrosis factor-alpha (TNF-alpha), which has recently been found to be present in the intimal thickening of human arteries. Therefore, we studied the effect of TNF-alpha on ICAM-1 mRNA content and surface expression in cultured human aortic SMCs by using the methods of Northern blotting and immunofluorescence flow cytometry. Under basal conditions of cultivation, ICAM-1 mRNA was not revealed in SMCs. However, treatment of the cells with recombinant human TNF-alpha induced substantial levels of ICAM-1 mRNA. The content of ICAM-1 on the surface of SMCs also increased in a dose- and time-dependent manner after incubation with TNF-alpha. Twenty-four hours of treatment with 10 ng/mL TNF-alpha led to an approximately 10-fold increase in ICAM-1 surface expression in the SMCs. Under the same conditions, pretreatment of SMCs with TNF-alpha resulted in a twofold increase of their adhesiveness for monocytes. In the presence of anti-ICAM-1 monoclonal antibody 10F3, monocyte adhesion to TNF-alpha-pretreated SMCs was significantly inhibited, suggesting that the observed monocyte-SMC interaction involved the ICAM-1 expressed on SMC surfaces as a result of TNF-alpha stimulation. These results led us to propose that TNF-alpha may act a regulator of functional ICAM-1 expression on the SMC surface and thus can increase the possibility of interactions between mononuclear cells and SMCs in atherosclerotic plaques.
Prostacyclin agonists reduce early atherosclerosis in hyperlipidemic hamsters. Octimibate and BMY 42393 suppress monocyte chemotaxis, macrophage cholesteryl ester accumulation, scavenger receptor activity, and tumor necrosis factor production.
Authors: Kowala M C , Mazzucco C E , Hartl K S , Seiler S M , Warr G A , Abid S , Grove R I
Published: June 2011

We determined the effects of two prostacyclin agonists (octimibate and BMY 42393) on the progression of the fatty streak in vivo and on macrophage function in vitro. Hamsters were fed chow plus 0.05% cholesterol and 10% coconut oil. Control hamsters were compared with animals receiving either octimibate (10 or 30 mg/kg per day) or BMY 42393 (30 mg/kg per day). After 10 weeks of treatment, octimibate decreased plasma total cholesterol and triglycerides by 43% and 32%, respectively. Neither agonist affected blood pressure or heart rate. Lesion-prone aortic arches were stained with hematoxylin and oil red O and examined en face. Compared with controls, octimibate and BMY 42393 on average decreased mononuclear cells attached to the luminal surface by 44% and reduced subendothelial macrophage-foam cell number by 56%, foam cell size by 38%, and fatty streak area by 63%. Since octimibate is a putative inhibitor of acyl coenzyme A cholesterol acyltransferase, we studied the effect of both agents on cholesteryl ester metabolism in murine macrophages. At 10 microM, octimibate and BMY 42393 decreased cholesteryl ester accumulation in macrophages by 90% and 41%, respectively. Octimibate inhibited cholesteryl ester synthesis by 96% and increased the rate of cholesteryl ester degradation by 52%. Both prostacyclin agonists reduced macrophage scavenger receptor-mediated uptake of acetylated low density lipoprotein by 24-66% and increased cyclic adenosine monophosphate levels. Octimibate and BMY 42393 inhibited the secretion of tumor necrosis factor by 80-88% when macrophages were activated with lipopolysaccharide. At 10 microM, both agents decreased human monocyte chemotaxis to N-formyl-methionyl-leucyl-phenylalanine by 64-79%. The in vitro results with octimibate and BMY 42393 are consistent with the low number of small foam cells quantified in vivo. We suggest that octimibate and BMY 42393 suppress monocyte-macrophage atherogenic activity and cytokine production and thus inhibit the development of early atherosclerosis.
Plasminogen activator inhibitor-1 mRNA is expressed in platelets and megakaryocytes and the megakaryoblastic cell line CHRF-288.
Authors: Konkle B A , Schick P K , He X , Liu R J , Mazur E M
Published: June 2011

Plasminogen activator inhibitor-1 (PAI-1) is present in the platelet alpha-granule and is released on platelet activation. Platelet PAI-1 could either be synthesized by the megakaryocyte or taken up from the plasma. In this report we confirm the presence of PAI-1 protein in human megakaryocytes by Western blot analysis and show its synthesis in guinea pig megakaryocytes by metabolic labeling. We document the presence of PAI-1 mRNA in human platelets and show a 3-kb mRNA species on Northern blot analysis of guinea pig megakaryocytes. Neither untreated CHRF-288 cells, a megakaryoblastic cell line, nor human erythroleukemia (HEL) cells expressed PAI-1 mRNA. Phorbol ester (phorbol 12-myristate 13-acetate, 160 nM) treatment of CHRF-288 and HEL cells for 4 days induced PAI-1 mRNA expression in CHRF-288 cells but not in HEL cells. These studies show that PAI-1 is synthesized by megakaryocytes. Megakaryocytes most likely determine the PAI-1 content of platelets and thereby establish the antifibrinolytic potential of the platelet.
Platelet aggregation induced by the endoperoxide analogue U46619 is inhibited by polymorphonuclear leukocyte ADPase activity.
Authors: Zatta A , Pandolfo L , Caparrotta L , Prosdocimi M , Dejana E , Del Maschio A
Published: June 2011

Platelet activation by the stable endoperoxide analogue U46619 is mediated largely by ADP released from platelet-dense granules. Polymorphonuclear leukocytes (PMNs) endowed with ecto-ADPase activity may operate as antiaggregatory cells in platelet aggregation induced by U46619. Unstimulated PMNs were effective in reducing aggregation when platelets were stimulated by threshold concentrations of U46619, whereas at higher concentrations of the stimulus, PMN activation is required. Evidence that the inhibition was mediated by PMN ecto-ADPase activity was obtained by high-performance liquid chromatography analysis, indicating that PMNs were able to efficiently metabolize platelet-active ADP into AMP. Moreover, PMN-derived supernatants were able to inhibit platelet aggregation, suggesting that under this circumstance the inhibition was exerted by an uncharacterized, releasable ADPase activity. This study supports the hypothesis that, besides nitric oxide and hydrogen peroxide, ADPase activity may represent another PMN-mediated pathway capable of regulating platelet activity in areas of reduced blood flow, such as those found in conditions of myocardial ischemia.
Comparison of ligand-binding sites of modeled apo[a] kringle-like sequences in human lipoprotein[a].
Authors: Guevara J , Jan A Y , Knapp R , Tulinsky A , Morrisett J D
Published: June 2011

Human lipoprotein[a] contains at least two high-molecular-weight, disulfide-linked apolipoproteins, apo[a] and apo B-100. Apo[a] is a highly glycosylated, hydrophilic apoprotein that somewhat resembles plasminogen by containing an extended kringle domain and a carboxyl-terminal serine protease domain. The apo[a] kringle domain is composed of 11 distinct kringle types. Ten of these display high sequence homology to plasminogen kringle 4 (PGK4). The crystallographic coordinates for PGK4 were used to generate three-dimensional molecular models of the apo[a] kringle types, and the lysine-binding region of PGK4 was used to compare the different potential receptor-ligand and ligand-binding sites contained in each different PGK4-like kringle of apo[a]. A receptor-ligand site can be proposed for each kringle type. Potential serine protease cleavage sites, containing arginine-threonine and threonine-arginine, are located on the surface of the kringles. The ligand-binding site of one apo[a] kringle model is almost identical to that of PGK4 and may be a lysine-binding site of apo[a]. Four other apo[a] kringle models appear to have structurally similar lysine-binding sites, but with differences that may influence ligand-polypeptide specificity. Five apo[a] kringle models have ligand-binding sites that probably do not bind lysine; one of these is the highly repeated kringle in the known apo[a] polymorph.
Plasma fibrinogen level is not elevated in young adults from families with premature ischemic heart disease.
Authors: Hoffman C J , Burns P , Lawson W E , Katz J P , Miller R H , Hultin M B
Published: June 2011

Several epidemiological studies have found that the plasma fibrinogen level is a risk factor for ischemic heart disease (IHD), similar in importance to the serum cholesterol level. A family history of IHD is also a significant risk factor for IHD, statistically independent of the serum cholesterol level. Whether the familial risk for IHD is related to genetic control of the fibrinogen level is unknown. Estimates of the genetic contribution to the variance in plasma fibrinogen levels vary markedly. We previously found elevated levels of cholesterol and factor VII in young subjects with a familial history of premature IHD. In the present study we chose to measure fibrinogen, factor VII antigen, and total cholesterol levels in 43 asymptomatic first-degree relatives (< 50 years old) of patients with premature IHD and in 43 age- and sex-matched asymptomatic young adults at low risk of IHD. No subjects in either group were smokers. The mean plasma fibrinogen level of the high-risk group (259 mg/dL) did not differ significantly from that of the low-risk group (250 mg/dL; p > 0.4). In contrast, the high-risk group had significantly higher mean factor VII antigen (p < 0.001) and mean serum cholesterol (p < 0.0001) than the low-risk group. These data argue against the hypothesis that genetic determination of the plasma fibrinogen level is a common pathophysiological mechanism responsible for familial risk of IHD.
Genetic variation at the beta-fibrinogen locus in relation to plasma fibrinogen concentrations and risk of myocardial infarction. The ECTIM Study.
Authors: Scarabin P Y , Bara L , Ricard S , Poirier O , Cambou J P , Arveiler D , Luc G , Evans A E , Samama M M , Cambien F
Published: June 2011

Increased plasma fibrinogen concentration is a major cardiovascular risk factor. Conflicting results on genetic variations in plasma fibrinogen levels have been reported. Furthermore, whether fibrinogen genotype is associated with the risk of ischemic heart disease has not been studied so far. An HaeIII restriction fragment length polymorphism of the beta-fibrinogen gene was used in a case-control study to investigate the genetic variation at this locus in relation to plasma fibrinogen concentrations and the risk of myocardial infarction (MI). Five hundred thirty-three male patients aged 27-66 years and 648 control subjects were recruited from four World Health Organization MONICA centers in Northern Ireland and in France. The absence of the HaeIII cutting site (H2 allele) was associated with a significant rise in fibrinogen concentrations in both patients and control subjects. The effect of the HaeIII polymorphism on plasma fibrinogen levels did not significantly differ between centers. Fibrinogen levels were higher in smokers than in nonsmokers. The difference between the two groups was larger in subjects with the genotype H2H2 than in those with either genotype H1H1 or H1H2, regardless of the case-control status. However, there was no significant interaction between smoking status and genotype in their effects on variance in fibrinogen levels, whereas fibrinogen levels. HaeIII genotype accounted for approximately 1% of the total variance in fibrinogen levels, whereas smoking and age together explained 7% and 5% in control subjects and patients, respectively. The frequency of the H2 allele was 0.21 in control subjects and 0.19 in patients.(ABSTRACT TRUNCATED AT 250 WORDS)
Dexamethasone-induced suppression of aortic atherosclerosis in cholesterol-fed rabbits. Possible mechanisms.
Authors: Asai K , Funaki C , Hayashi T , Yamada K , Naito M , Kuzuya M , Yoshida F , Yoshimine N , Kuzuya F
Published: June 2011

We investigated the mechanisms by which corticosteroids affect atherosclerosis. Male New Zealand White rabbits were injected with 0.125 mg dexamethasone (n = 10) or vehicle (control group, n = 10). Both groups were fed a 1% cholesterol diet for 8 weeks. Although the dexamethasone-treated animals exhibited a greater degree of hyperlipidemia, they exhibited significantly less atherosclerotic plaque of the aortic surface than control animals (7.8% versus 47.2%). Immunofluorescence study of the aortic plaque specimens showed that dexamethasone administration reduced both macrophages and T lymphocytes. In vitro, dexamethasone suppressed the proliferation and differentiation of U937 cells and inhibited uptake and degradation of beta-very low density lipoproteins by mouse peritoneal macrophages. These findings suggest that dexamethasone suppresses the development of atherosclerosis in the aorta of rabbits by inhibiting recruitment and proliferation of macrophages and the formation of foam cells in plaques.
Recombinant human thrombomodulin attenuates human endothelial cell activation by human thrombin.
Authors: Parkinson J F , Bang N U , Garcia J G
Published: June 2011

Two glycoforms of recombinant human thrombomodulin (TM; TMD1-105 and TMD1-75), an endothelial cell membrane protein, were tested for their ability to alter thrombin-induced activation of cultured human umbilical vein endothelial cells (HUVECs). After stimulation with 10 nmol/L thrombin, HUVEC generation of inositol-1,4,5-trisphosphate (IP3), a potent Ca(2+)-mobilizing second messenger, was dose-dependently blocked by TMD1-105. Both TMD1-105 (IC50 = 10 nmol/L) and TMD1-75 (IC50 = 100 nmol/L) blocked the enhanced prostacyclin synthesis by HUVEC monolayers treated with 10 nmol/L thrombin. HUVEC monolayer permeability to Evans blue dye-labeled albumin increased from 0.125 +/- 0.06 microL/min in control experiments to 0.380 +/- 0.09 microL/min after treatment with 100 nmol/L thrombin (P < .05). Incubation of HUVECs with TMD1-105 alone (600 nmol/L) had no effect (0.114 +/- 0.04 microL/min) on basal permeability. In contrast, incubation of 100 nmol/L thrombin with 600 nmol/L TMD1-105 reduced this increase in HUVEC permeability to almost control levels (0.142 +/- 0.06 microL/min). These results demonstrate that recombinant human TM, a potent in vitro anticoagulant, also functions as an antagonist of thrombin receptor-mediated HUVEC activation. In addition to its anticoagulant functions, the high-affinity endothelial cell receptor TM may play a role in modulating endothelial cell activation by thrombin.
Dietary monounsaturated fatty acids enhance cholesterol efflux from human fibroblasts. Relation to fluidity, phospholipid fatty acid composition, overall composition, and size of HDL3.
Authors: Sola R , Motta C , Maille M , Bargallo M T , Boisnier C , Richard J L , Jacotot B
Published: June 2011

This study was designed to determine whether modifications induced by dietary fats on the high-density lipoprotein3 (HDL3) physicochemical characteristics could affect cholesterol efflux and intracellular cholesterol content, leading to upregulation of low-density lipoprotein (LDL) receptor activity from cultured fibroblasts. Serum HDL3S were obtained from 12 healthy women aged 26 to 49 years who adhered to four 7-week isocaloric diets containing 30% of the caloric intake as fat. Of the total calories, 15.6% of each diet was provided by (1) milk fats, rich in saturated fatty acids; (2) sunflower oil, rich in n-6 polyunsaturated fatty acids; (3) olive oil, rich in monounsaturated fatty acids; and (4) rapeseed oil, rich in n-3 polyunsaturated fatty acids. HDL3 isolated after the monounsaturated fatty acid diet induced the greatest cellular [3H]free cholesterol efflux, reduced the content of intracellular cholesterol, and enhanced 125I-LDL degradation. Univariate regression analyses suggested that the increased capacity of HDL3 to promote cellular [3H]free cholesterol efflux was in part due to its greater fluidity, higher cholesteryl ester content, elevated linoleic to linolenic acid ratio in phospholipids, and its smaller size. In conclusion dietary fats induced physicochemical changes in HDL3, which strongly modulated cellular cholesterol homeostasis in vitro. These data also suggest a novel mechanism by which dietary fats exert their effect on atherosclerosis.
Inhibitory effect of clopidogrel on platelet adhesion and intimal proliferation after arterial injury in rabbits.
Authors: Herbert J M , Tissinier A , Defreyn G , Maffrand J P
Published: June 2011

The possible activity of ticlopidine and its analogue clopidogrel in early atherogenesis was investigated. Incubation of rabbit platelets with the extracellular matrix produced by endothelial cells in culture induced massive platelet adherence in vitro. This phenomenon was strongly reduced when platelets were isolated from rabbits that had been treated with a single dose of clopidogrel (10 mg/kg PO) or three doses of ticlopidine (each 200 mg/kg PO) (94% and 56% inhibition of platelet adhesion, respectively). Three doses of aspirin (each 200 mg/kg PO) were ineffective. Air-drying injury of the rabbit carotid artery resulted in platelet adherence to the underlying subendothelium. This platelet accumulation on the damaged vessel wall was greatly reduced by clopidogrel: 95% (P < .001) inhibition of platelet adhesion after a single oral dose of 25 mg/kg. Ticlopidine (200 mg/kg) was also effective (71% inhibition; P < .001), whereas aspirin (100 mg/kg PO) failed to reduce platelet adhesion to the subendothelium. The effect of clopidogrel on intimal smooth muscle hyperplasia in rabbit carotid arteries subjected to air-drying endothelial injury was then investigated. After a 16-day treatment, clopidogrel (25 mg/kg per day PO) inhibited the development of intimal thickening (48% inhibition; P < .01). This effect was dose dependent and increased with the duration of the treatment. Under the same experimental conditions, ticlopidine (200 mg/kg per day PO) inhibited myointimal thickening (57%; P < .001), whereas aspirin was ineffective. These results show that clopidogrel and ticlopidine, two ADP-selective antiplatelet agents, can reduce myointimal thickening after endothelial injury. This effect can be due to the inhibition of platelet adhesion and aggregation to the exposed subendothelium.
Noninvasive quantitative evaluation of atherosclerosis using MRI and image analysis.
Authors: Merickel M B , Berr S , Spetz K , Jackson T R , Snell J , Gillies P , Shimshick E , Hainer J , Brookeman J R , Ayers C R
Published: June 2011

A new medical image analysis system to quantify atherosclerosis in the lower abdominal aorta using magnetic resonance imaging is described. This medical image analysis and display system permits the quantification of the three-dimensional (3D) properties of the vessel wall and lumen cross-sectional area and volumes. Preliminary results of employing this medical image analysis capability on magnetic resonance images demonstrated a twofold increase in wall volume per unit vessel length, corresponding to intimal thickening, before luminal narrowing was detected. This work demonstrated the feasibility and usefulness of quantitatively evaluating the 3D properties of the vessel lumen and wall by using a combination of magnetic resonance imaging and image analysis. The demonstration that intimal wall thickening is observed in images before observable occlusion of the lumen can be expected to provide an important early indicator of the future development of atherosclerosis. Such capability will permit detailed and quantitative studies to assess the effectiveness of therapies, such as drug, exercise, and dietary regimens.
Functional significance of mobile receptors on human platelets.
Authors: White J G
Published: June 2011

Mobile receptors on surface- and suspension-activated platelets bind a variety of specific and nonspecific antigens and particulates and clear them from the plasma membrane to channels of the open canalicular system (OCS). The present study examined the interaction of platelets with latex spherules of increasing size to identify the role of mobile receptors and binding sites in hemostatic physiology. Small latex spherules 0.09 to 3.13 microns in average diameter were cleared from peripheral margins to central zones and the OCS on surface-activated platelets and from the surface membrane to the OCS of platelets in suspension. Larger spheres, 6.4 microns in diameter, could not be moved across the membranes of solid phase- and fluid phase-activated platelets. Instead, platelets moved their surface membranes through the contact sites fixed on the surface of immobile spheres, bringing interior membranes of the OCS channels to the latex. This change, in which mobile membranes move through fixed contact sites rather than mobile receptor complexes moving across plasma membranes, results in evagination of almost all OCS channels on large latex spherules. A similar mechanism may be involved in the interaction of platelets with relatively flat surfaces, such as denuded subendothelium.
Polymorphonuclear leukocytes enhance release of growth factors by cultured endothelial cells.
Authors: Totani L , Piccoli A , Pellegrini G , Di Santo A , Lorenzet R
Published: June 2011

Porcine aortic endothelial cells (PAECs) in culture constitutively secrete polypeptide (endothelium-derived) growth factors (EDGFs) into the surrounding medium. Incubation of PAECs with human peripheral blood polymorphonuclear leukocytes (PMNs) caused a significant increase in EDGF release as assessed by [3H]thymidine incorporation into BALB/c 3T3 mouse fibroblasts and cell proliferation assay. The effect was time dependent and correlated with the number of PMNs, reaching a maximum with a 1:1 PAEC to PMN ratio. Generation of mitogenic activity was prevented by cycloheximide, indicating a requirement for de novo protein synthesis. Antibody-mediated inhibition assays suggested that mitogenic activity was due to platelet-derived growth factor and basic fibroblast growth factor. When supernatant from N-formyl-methionyl-leucyl-phenylalanine-stimulated PMNs was substituted for PMNs during incubation with PAECs, powerful mitogenic activity was generated, indicating the involvement of soluble mediators. A role for free oxygen radicals was ruled out by experiments in which superoxide dismutase and catalase did not prevent the increase in mitogenic activity. By contrast, serine protease inhibitors such as soybean trypsin inhibitor, alpha 1-antitrypsin, and eglin C reduced the PMN-stimulating activity by 70%, 80%, and 100%, respectively. The possible involvement of cathepsin G and elastase was investigated. Cathepsin G and elastase, when substituted for PMNs, increased the release of EDGFs in a dose-dependent fashion, mimicking the effect of PMNs. These findings suggest a new role for leukocyte-vessel wall interactions in the proliferative feature of atherosclerosis.
Serum estrone concentrations and coronary artery disease in postmenopausal women.
Authors: Cauley J A , Gutai J P , Glynn N W , Paternostro-Bayles M , Cottington E , Kuller L H
Published: June 2011

Little is known about the relation between serum sex hormones and either coronary heart disease or the development of atherosclerosis in women. We measured serum estrone concentrations in 87 postmenopausal women (age, 50 to 81 years) who were admitted for diagnostic cardiac catheterization. None of the women were on estrogen replacement therapy. Cases (n = 62) were defined as those women who had > or = 1 coronary artery with > or = 50% occlusion. All control subjects (n = 25) had 0% to 24% occlusion of all coronary arteries. Estrone concentrations, as measured by a combination of extraction, column chromatography, and radioimmunoassay, showed little difference between cases and control subjects. A difference of 6 pg/mL in the estrone level was not associated with a significantly increased risk of coronary artery disease (odds ratio [OR], 1.85; 95% confidence intervals [CI], 0.60, 5.2). Examination of mean estrone levels on the basis of the number of occluded vessels was also not significant. The primary predictors of coronary artery disease in this population were a history of diabetes (OR, 8.8; CI, 1.5, 51.4) and age (5-year increments; OR, 2.1; CI, 1.2, 3.8). There was also some suggestion that women who reported higher lifetime physical activity levels were at a reduced risk for developing coronary artery disease (OR, 0.18; CI, 0.05, 0.65). These preliminary results do not support the hypothesis that serum estrogens are related to coronary artery disease in older women, but these findings need to be replicated in larger populations of older women.
Probucol reduces the cellularity of aortic intimal thickening at anastomotic regions adjacent to prosthetic grafts in cholesterol-fed rabbits.
Authors: Baumann D S , Doblas M , Schonfeld G , Sicard G A , Daugherty A
Published: June 2011

Intimal hyperplasia is a persistent problem after implantation of prosthetic grafts. Although the mechanisms underlying this hyperplastic response are unknown, it has been proposed that such responses may be due to chronic vascular injury similar to that of atherogenesis. Thus, the role of oxidation was explored using the potent antioxidant drug probucol. Adult New Zealand White rabbits fed a modestly (0.25%) cholesterol-enriched diet had a polytetrafluoroethylene prosthetic graft placed into the lower aorta. After the grafting procedure, a group of 11 rabbits was placed on the cholesterol-enriched diet supplemented with 1% wt/wt probucol while a control group of 10 rabbits was placed on the cholesterol-enriched diet alone. The rabbits were maintained for a further 10 weeks before histological examination of the area surrounding the graft. Although administration of probucol did not significantly alter the dimensions of lesions at the anastomotic sites, the drug promoted striking histological changes in the surrounding tissue. Both groups of rabbits had a similar intimal hyperplastic response of the aortic tissue surrounding the graft. The vascular lesions present in the perigraft region of the control group consisted of a normal-appearing media but a thickened intima. The thickened intima contained numerous smooth muscle cells in a network of extracellular matrix. Regions in the neointima that were rich in smooth muscle cells exhibited modest staining for proliferating cell nuclear antigen. A few macrophages were present in the control group as determined by immunostaining with the monoclonal antibody RAM-11. In contrast, administration of probucol led to a marked reduction in the presence of RAM-11-staining macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)
Microvascular endothelial cell sodding of 1-mm expanded polytetrafluoroethylene vascular grafts.
Authors: Ahlswede K M , Williams S K
Published: June 2011

The formation of an endothelial cell lining on the inner surface of polymeric grafts may reduce the inherent thrombogenicity of synthetic implants. Endothelial cell transplantation onto the luminal surface of grafts has been suggested as one method of creating new endothelial cell linings on grafts. The purpose of this study was to morphologically evaluate the very early events of healing (between 4 and 14 days) of 1-mm-internal-diameter expanded polytetrafluoroethylene (ePTFE) grafts that were treated with autologous microvessel endothelial cells at the time of graft implantation. We evaluated the development of new intimal linings in microvascular endothelial cell-sodded 1-mm ePTFE vascular grafts and compared their healing characteristics with non-cell-treated grafts by using a rat aortic graft model. Endothelial cells were isolated from intraperitoneal fat pads of female rats and transplanted onto the grafts by using a pressure sodding method. One-centimeter-long grafts were immediately implanted as interpositional grafts in the aorta. Non-cell-treated grafts were also implanted. Grafts were explanted 4, 7, and 14 days after implantation and were evaluated by light and scanning electron microscopy. Morphometric analysis of the graft surfaces revealed the cellular coverage in sodded grafts to be 93.7 +/- 8.7% and in nonsodded grafts, 1.1 +/- 1.9%. Areas not covered by cells exhibited thrombus and bare graft. The luminal lining of cells exhibited morphological characteristics, indicating they were antithrombogenic, based on morphological criteria, and exhibited characteristics of endothelium.(ABSTRACT TRUNCATED AT 250 WORDS)
LDLs increase the exposure of fibrinogen binding sites on platelets and secretion of dense granules.
Authors: van Willigen G , Gorter G , Akkerman J W
Published: June 2011

Because previous studies show that lipoproteins affect platelet aggregation, we studied the effect of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) on the binding of fibrinogen, which mediates platelet-platelet contact. Neither LDL nor HDL induced 125I-fibrinogen binding at concentrations up to 2 g protein/L. In contrast, platelets stimulated with 10 mumol/L ADP bound 63 734 +/- 2453 molecules of fibrinogen per platelet. A 5-minute preincubation with LDL (0.5 to 2 g/L protein) induced a dose-dependent increase to 91 307 +/- 2164 molecules of fibrinogen per platelet at 1.5 g/L, which is in the range found after optimal stimulation with alpha-thrombin. The increased fibrinogen binding in the presence of LDL resulted in faster aggregation with a 16% increase in single platelet disappearance and a faster optical aggregation at 5 mumol/L ADP and 1.5 g protein/L LDL. Inhibition of prostaglandin G2/H2-thromboxane A2 formation with indomethacin (30 mumol/L) did not change the stimulation by LDL. In contrast, modification of lysine residues of LDL, which is known to prevent specific binding to platelets, completely abolished the effect of LDL. Under the same conditions HDL did not change fibrinogen binding or aggregation. LDL also enhanced alpha-thrombin-induced [14C]serotonin secretion, but this property was not affected by lysine modification of LDL. These data indicate that LDL enhances platelet aggregation by stimulating the mechanisms that control exposure of fibrinogen binding sites on the glycoprotein IIB/IIIA complex via a mechanism that differs from the effect of LDL on secretion.