bluuebunny/crossref_metadata_2025 huggingface dataset:
Smooth Muscle Cell Heterogeneity in Pulmonary and Systemic Vessels
Authors: Frid Maria G. , Dempsey Edward C. , Durmowicz Anthony G. , Stenmark Kurt R.
Published: June 2011

AbstractExperimental evidence is rapidly accumulating which demonstrates that the arterial media in both pulmonary and systemic vessels is not composed of a phenotypically homogeneous population of smooth muscle cells (SMCs) but rather of heterogeneous subpopulations of cells with unique developmental lineages. In vivo and in vitro observations strongly suggest that marked differences in the phenotype, growth, and matrix-producing capabilities of phenotypically distinct SMC subpopulations exist and that these differences are intrinsic to the cell type. These data also suggest that differential proliferative and matrix-producing capabilities of distinct SMC subpopulations govern, at least in part, the pattern of abnormal cell proliferation and matrix protein synthesis observed in the pathogenesis of vascular disease. Within the pulmonary circulation, the observation that the isolated medial SMC subpopulations exhibit differential proliferative responses to hypoxic exposure is important, since this in vitro cell-model system can now be used to better understand the mechanisms that regulate increased responsiveness of specific medial cell subpopulations to low oxygen concentrations. Our data also support the idea that protein kinase C is likely to be one important determinant of differential cell growth responses to hypoxia. The data also suggest differential involvement of specific arterial SMC subpopulations in the elastogenic responses of the vessel wall to injury. We believe that a better understanding of the mechanisms contributing to the unique behavior of specific arterial cell subpopulations will provide important future directions for therapies aimed at preventing abnormal cell replication and matrix protein synthesis in vascular disease.
Effect of Serum Lipids, Lipoproteins, and Apolipoproteins on Vascular and Nonvascular Mortality in the Elderly
Authors: Räihä I. , Marniemi J. , Puukka P. , Toikka T. , Ehnholm C. , Sourander L.
Published: June 2011

AbstractThe purpose of this study was to determine the effect of serum lipids, lipoprotein fractions, and apolipoprotein (apo) A-1, B, and E on mortality from vascular and nonvascular causes in an unselected elderly population. The random sample of 347 community-living individuals aged 65 years or older was obtained in 1982. Serum total cholesterol, LDL cholesterol (LDL-C), HDL cholesterol (HDL-C), triglyceride, and apo A-1, B, and E were determined at baseline. After the 11-year follow-up, 199 of the participants had died, and 148 were still alive. Mortality data from vascular and nonvascular causes by the end of 1993 were obtained from official registers. In the univariate analysis, a low total cholesterol level was associated with death due to both vascular and nonvascular causes (Pvalue for trend, .021 and .0027, respectively). After the adjustment for other risk factors, the inverse association between total cholesterol and vascular mortality disappeared, but low total cholesterol was still a significant predictor of death due to nonvascular causes. Adjusted relative risks (RRs) of death due to nonvascular causes for those with elevated total cholesterol (5.1 to 6.5, 6.6 to 8.0, and >8.0 mmol/L) compared with the reference group (≤5.0 mmol/L) were 0.5 (95% confidence interval [CI], 0.2 to 1.2), 0.6 (0.2 to 1.0), and 0.2 (0 to 0.8), respectively. Neither concentrations of HDL-C, LDL-C, triglyceride, nor apo B were associated with vascular or nonvascular mortality. On the other hand, low concentration of apo A-1 predicted vascular death. The RR for the lowest tertile was 1.6 (1.1 to 2.5) compared with the highest tertile. Furthermore, the occurrence of the apo E e4 allele was associated with increased risk of vascular mortality (RR, 1.5; 95% CI, 1.0 to 2.2), but the risk was not related to the levels of lipids, lipoproteins, or other apolipoproteins at baseline. Nonvascular mortality also tended to be predicted by the presence of the e4 allele (RR, 1.5; 95% CI, 0.9 to 2.5). In an unselected elderly population, the allelic variation of apo E, ie, the presence of the e4 allele, and a low concentration of apo A-1 were more accurate indicators of vascular mortality than total cholesterol or lipoprotein fractions. The risk associated with the apo E polymorphism is unrelated to dyslipidemia.
Lysophosphatidylcholine Promotes Cholesterol Efflux From Mouse Macrophage Foam Cells
Authors: Hara Seijiro , Shike Tsutomu , Takasu Nobuo , Mizui Takuji
Published: June 2011

Abstract
We examined the effects of lysophosphatidylcholine (lyso-PC) on promoting cholesterol efflux from macrophage foam cells. Mouse peritoneal macrophages were converted to foam cells by incubation with [
3
H]cholesteryl linoleate–labeled or unlabeled acetyl-LDL. When these cells were incubated with lyso-PC, [
3
H]cholesterol release was promoted in relation to both dose and time, and cellular cholesterol mass was decreased, while medium cholesterol mass was increased. These cholesterol efflux–promotive effects of lyso-PC were confirmed by the fact that the lyso-PC–treated cells showed less oil red O staining than the control cells. ApoE secretion, estimated by Western blotting of the medium, was also augmented by lyso-PC. Both the cholesterol and apoE released by lyso-PC treatment were floated by ultracentrifugation of the medium after its density had been adjusted to 1.210 g/mL. By electron microscopic analysis, vesicular lipoproteins were observed in ultracentrifugally concentrated conditioned medium of lyso-PC. Monensin, a protein secretion inhibitor, effectively inhibited [
3
H]cholesterol release induced by lyso-PC but not by apoA-I. These results suggest that lyso-PC may inhibit the development of atherosclerosis or enhance its regression by stimulating cholesterol efflux from macrophage foam cells.
D-Dimer and Anticoagulation in Patients With Mechanical Prosthetic Heart Valves
Authors: Giansante Carlo , Fiotti Nicola , Calabrese Salvatore , La Verde Rosa , Pandullo Claudio , Scardi Sabino , Guarnieri Gianfranco
Published: June 2011

Abstract
The best anticoagulation level in patients with mechanical heart valve prostheses is still being debated. D-dimer, which detects the presence of cross-linked fibrin degradation products, has been demonstrated to be a useful marker of coagulation activation. This study was designed to verify whether heart valve prostheses in anticoagulated patients are associated with abnormalities in D-dimer plasma levels, and if so, whether such levels are related to the anticoagulation level and/or whether they could be predictive of acute vascular or hemorrhagic events. In 132 patients with single and 10 with double mechanical valve replacement, international normalized ratio (INR) and D-dimer plasma levels were determined. The INR levels of the previous 8 months were reviewed to assess the time that each patient spent in the therapeutic range. The D-dimer plasma levels were compared with those obtained from 102 matched control subjects. The patients were then followed up for 2 years to record acute vascular and hemorrhagic events. For the entire group, D-dimer plasma levels in patients were the same as those in the control group. Patients with double valve replacement had higher D-dimer plasma levels than either monovalvular implant patients or control subjects. Patients who had spent <75% of the time within the assigned anticoagulation range had higher values for D-dimer plasma levels (median, 270 vs 198 ng/mL,
P
=.02). The major determinants of D-dimer plasma levels were age (
R
2
=.07,
P
=.009) and the percentage of time spent below the predetermined INR level (
R
2
=.09,
P
=.001). During follow-up, 19 acute vascular and 16 hemorrhagic events occurred. High D-dimer tertile was the only parameter predicting the occurrence of thromboembolic events. In patients with mechanical heart valve prostheses, the D-dimer plasma level depended on the thoroughness of anticoagulation. Patients in the upper tertile of D-dimer values have an ≈5-fold risk of vascular thromboembolic events. D-dimer determination can therefore be useful in detecting patients who are at a higher risk of severe vascular events.
Persistent Thrombin Generation During Heparin Therapy in Patients With Acute Coronary Syndromes
Authors: Merlini Piera Angelica , Ardissino Diego , Bauer Kenneth A. , Oltrona Luigi , Pezzano Antonio , Bottasso Biancamaria , Rosenberg Robert D. , Mannucci Pier Mannuccio
Published: June 2011

Abstract
Intravenous heparin, a fundamental therapy in the treatment of patients with acute coronary syndromes, acts by inhibiting thrombin and activated factors X, IX, XI, and XII. It has also been demonstrated that heparin reduces plasma fibrinopeptide A, a marker of thrombin activity, but it is unknown whether it decreases prothrombin fragment 1+2, an indirect marker of thrombin generation. We measured the plasma levels of prothrombin fragment 1+2, fibrinopeptide A, and antithrombin III in 64 consecutive patients with unstable angina or myocardial infarction receiving intravenous heparin. Blood samples were obtained at baseline (before any treatment) and then at 90 minutes and 24 and 48 hours after the administration of an intravenous bolus of heparin (5000 IU) followed by a continuous infusion of 1000 IU per hour to maintain activated partial thromboplastin time at more than double its baseline levels. In comparison with baseline, there was a significant decrease in fibrinopeptide A at 90 minutes and at 24 and 48 hours (baseline, 2.3 nmol/L; 90 minutes, 1.15 nmol/L; 24 hours, 1.4 nmol/L; 48 hours, 1.2 nmol/L;
P
<.0001) but no change in prothrombin fragment 1+2 levels (baseline, 1.27 nmol/L; 90 minutes, 1.3 nmol/L; 24 hours, 1.33 nmol/L; 48 hours, 1.29 nmol/L;
P
=NS). Antithrombin III activity decreased at 24 and 48 hours (baseline, 108%; 24 hours, 97%; 48 hours, 95%;
P
<.0001). Hence, in patients with acute coronary syndromes, intravenous heparin at a dose reaching an activated partial thromboplastin time that adequately suppresses thrombin activity does not suppress increased thrombin generation.
Relation of Plaque Lipid Composition and Morphology to the Stability of Human Aortic Plaques
Authors: Felton C. V. , Crook D. , Davies M. J. , Oliver M. F.
Published: June 2011

Abstract
The propensity of atherosclerotic plaques to disrupt may be influenced by their lipid content and the distribution of these lipids within the plaque. To investigate this, we analyzed the morphological and lipid profiles of 668 human aortic plaques from 30 males who had died of ischemic heart disease. Plaques were classified as disrupted or as intact types A or B, the latter distinction being based on the absence or presence, respectively, of disrupted plaques within the same aorta. Disrupted plaques have a greater content of lipid (
P
<.001) and macrophages (
P
<.001) as well as a thinner cap (
P
<.001) than intact plaques. Lipid concentrations are positively associated with macrophage accumulation in all plaque types and are negatively associated with minimum cap thickness at the edge of disrupted plaques (
P
<.05). Free cholesterol concentration is inversely associated with minimum cap thickness at the center of type B plaques only (
P
<.05). At the center of intact type A and B and disrupted plaques, the free-to-esterified cholesterol ratios were 0.9 (range, 0.0 to 2.7), 0.8 (0.0 to 3.9), and 1.6 (0.2 to 4.0), respectively. Esterified cholesterol concentrations were higher at the center of type B plaques, and those of free cholesterol were higher at the center of disrupted plaques. At the edge of disrupted plaques, the free-to-esterified cholesterol ratio was 0.5 (0.0 to 2.7) because of the accumulation of esterified cholesterol. Concentrations of all fatty acids were increased at the edge of disrupted plaques compared with the center, but as a proportion of total fatty acids, omega6-polyunsaturated fatty acids (PUFAs) were lower (44% versus 46%,
P
<.01), possibly reflecting oxidation of PUFAs. These data demonstrate differences in lipid composition and intraplaque lipid distribution between intact and disrupted plaques. At the edge of advanced plaques, increased esterified lipid concentrations, inversely associated with cap thickness, may reflect macrophage activity and a predisposition to rupture.
Skipping of Exon 14 and Possible Instability of Both the mRNA and the Resultant Truncated Protein Underlie a Common Cholesteryl Ester Transfer Protein Deficiency in Japan
Authors: Gotoda Takanari , Kinoshita Makoto , Ishibashi Shun , Inaba Toshimori , Harada Kenji , Shimada Masako , Osuga Jun-ichi , Teramoto Tamio , Yazaki Yoshio , Yamada Nobuhiro
Published: June 2011

Abstract
Among the Japanese population, a G-to-A mutation at the beginning of intron 14 of the human cholesteryl ester transfer protein (CETP) gene is a frequent cause of CETP deficiency characterized by markedly increased HDL cholesterol. The resulting abnormalities responsible for null CETP deficiency were studied in detail. The CETP mRNA transcripts amplified by polymerase chain reaction from the monocyte-derived macrophages of two homozygous patients were both found to be normal except for the whole deletion of exon 14. The deletion causes a shift of reading frame and introduces a premature termination codon downstream. Examination of the macrophage RNA from heterozygotes suggested the increased instability of the abnormal mRNA in the cytoplasm, because the amount of the aberrant transcript was nearly one third that of a normal transcript in the cytoplasm, while they were equal in the nucleus. Although this indicated the synthesis of a mutant CETP that lacks about 15% at its carboxy terminus, immunoblot analysis demonstrated that the abnormal CETP was virtually absent in both the media and cell lysates of transfected COS-1 cells, which massively expressed the mutant CETP mRNA. These results elucidate the primary abnormality due to the common CETP splicing mutation to be the exon skipping of mRNA, which decreases the level of mRNA and produces a truncated protein that should be rapidly degraded intracellularly.
Therapeutic Response to Medium-Chain Triglycerides and ω-3 Fatty Acids in a Patient With the Familial Chylomicronemia Syndrome
Authors: Rouis Mustapha , Dugi Klaus A. , Previato Lorenzo , Patterson Amy P. , Brunzell John D. , Brewer H. Bryan , Santamarina-Fojo Silvia
Published: June 2011

Abstract
We have studied the underlying molecular defect in a patient presenting with recurrent pancreatitis, hypertriglyceridemia, and virtually undetectable postheparin plasma lipoprotein lipase (LPL) mass and activity, who normalized her triglycerides 3 to 6 months after initiation of either medium-chain triglyceride (MCT) oil or ω-3 fatty acid (ω-3-FA) therapy. After treatment, postheparin plasma LPL activity and mass ranged from 24% to 39% of normal and LPL specific activity was normal (1.0 nmol·ng
−1
·min
−1
). On discontinuation of MCT oil or ω-3-FA, plasma triglyceride increased to >2000 mg/dL. Northern blotting revealed both normal size and abundance of LPL mRNA isolated from adipocytes as well as macrophages. Sequence analysis of the LPL gene, which included all 10 exons, intron-exon splice junctions, and 1.7 kb of the 5′-flanking region, and of LPL cDNA failed to identify any mutations. ApoC-II activity and mass assays revealed the presence of normal levels of a fully functional cofactor as well as the absence of circulating plasma inhibitors of lipase function. In summary, we describe a unique patient presenting with classical features of the familial chylomicronemia syndrome who manifests an unusually beneficial therapeutic response to MCT oil and ω-3-FA therapy. Unlike that in most patients with LPL deficiency, the chylomicronemia in this patient is not caused by a mutation in the structural LPL gene but possibly by a posttranscriptional defect. Thus, a subset of LPL-deficient patients with unique genetic defects respond to therapy by normalizing fasting plasma triglycerides; a therapeutic trial with MCT oil should be considered in all patients presenting with the familial chylomicronemia syndrome.
Lipoprotein Lipase Can Function as a Monocyte Adhesion Protein
Authors: Obunike Joseph C. , Paka Swarnalatha , Pillarisetti Sivaram , Goldberg Ira J.
Published: June 2011

Abstract
Lipoprotein lipase (LPL) is made by several cell types, including macrophages within the atherosclerotic lesion. LPL, a dimer of identical subunits, has high affinity for heparin and cell surface heparan sulfate proteoglycans (HSPGs). Several studies have shown that cell surface HSPGs can mediate cell binding to adhesion proteins. Here, we tested whether LPL, by virtue of its HSPG binding, could mediate monocyte adhesion to surfaces. Monocyte binding to LPL-coated (1-25 μg/mL) tissue culture plates was 1.4- to 7-fold higher than that of albumin-treated plastic. Up to 3-fold more monocytes bound to the subendothelial matrix that had been pretreated with LPL. LPL also doubled the number of monocytes that bound to endothelial cells (ECs). Heparinase and heparitinase treatment of monocytes or incubation of monocytes with heparin decreased monocyte binding to LPL. Heparinase/heparitinase treatment of the matrix also abolished the LPL-mediated increase in monocyte binding. These results suggest that LPL dimers mediate monocyte binding by forming a “bridge” between matrix and monocyte surface HSPGs. Inhibition of LPL activity with tetrahydrolipstatin, a lipase active-site inhibitor, did not affect the LPL-mediated monocyte binding. To assess whether specific oligosaccharide sequences in HSPGs mediated monocyte binding to LPL, competition experiments were performed by using known HSPG binding proteins. Neither antithrombin nor thrombin inhibited monocyte binding to LPL. Next, we tested whether integrins were involved in monocyte binding to LPL. Surprisingly, monocyte binding to LPL-coated plastic and matrix was inhibited by ≈35% via integrin-binding arginine-glycine–aspartic acid peptides. This result suggests that monocyte binding to LPL was mediated, in part, by monocyte cell surface integrins. In summary, our data show that LPL, which is present on ECs and in the subendothelial matrix, can augment monocyte adherence. This increase in monocyte-matrix interaction could promote macrophage accumulation within arteries.
Evidence for Prolonged Cell-Surface Contact of Acetyl-LDL Before Entry Into Macrophages
Authors: Zha Xiaohui , Tabas Ira , Leopold Philip L. , Jones Nancy L. , Maxfield Frederick R.
Published: June 2011

Abstract
Acetyl-LDL stimulates acyl-CoA:cholesterol acyltransferase (ACAT) much more effectively than LDL in mouse peritoneal macrophages. Previous work with another potent ACAT stimulator, β-VLDL, suggested that atherogenic lipoproteins may use internalization pathways distinct from that of LDL. Brief incubation of fluorescently labeled acetyl-LDL and LDL followed by a short chase period without lipoproteins was used to compare endocytic pathways. LDL was delivered rapidly to perinuclear vesicles, corresponding to late endosomes and lysosomes. A substantial fraction (>40%) of acetyl-LDL was initially retained in the cell periphery, while the rest was rapidly delivered to late endosomes that also contained LDL. Fluorescence of peripheral 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI)–acetyl-LDL could be quenched by TNBS, indicating accessibility of the peripheral acetyl-LDL to the extracellular space. Quantification of fluorescence intensities demonstrated that >40% of the cell-associated DiI–acetyl-LDL but only about 10% of DiI-LDL fluorescence was quenchable by TNBS after a 3-minute chase. Fucoidin can efficiently displace DiI–acetyl-LDL bound to cells at 0°C. DiI–acetyl-LDL in the TNBS-quenchable peripheral compartments, however, was resistant to fucoidin. Electron microscopy of colloidal gold–acetyl-LDL showed that acetyl-LDL on the cell surface was often associated with microvilli or ruffles. After clearance from the surface, the peripheral acetyl-LDL was also delivered to the late endosomes and lysosomes. These results indicate that a substantial portion of acetyl-LDL enters macrophages through a pathway that initially differs from that of LDL. This pathway involves a prolonged retention of acetyl-LDL on the plasma membrane. This surface retention may affect ACAT activation in macrophages.
Increased Oxidation of LDL in Patients With Coronary Artery Disease Is Independent From Dietary Vitamins E and C
Authors: Halevy Daniel , Thiery Joachim , Nagel Dorothea , Arnold Sebastian , Erdmann Erland , Höfling Berthold , Cremer Peter , Seidel Dietrich
Published: June 2011

Abstract
There is increasing experimental evidence that oxidation of LDL plays a major role in the pathogenesis of coronary artery disease (CAD). However, results from clinical studies on LDL oxidation and CAD are not consistent. In most studies only single plasma factors of LDL oxidation have been determined. We studied 207 patients who underwent coronary angiography. They were divided into subjects with CAD (n=137) and those without CAD (n=70). We determined the susceptibility of LDL to in vitro oxidation (lag phase), potential prooxidative and antioxidative plasma factors (plasma vitamin E, LDL vitamin E, ascorbate, iron, copper, ferritin, and ceruloplasmin), and markers of in vivo LDL oxidation (autoantibodies to malondialdehyde-modified LDL, oxidized LDL, and thiobarbituric acid–reactive substances), plasma lipids and lipoproteins, smoking habits, and other coronary risk factors in both groups. The lag phase was significantly shorter in patients with CAD than in patients without CAD (101± 38.6 versus 119± 40.6 minutes,
P
<.01). There was no correlation between the lag phase and the other oxidation parameters or the coronary risk factors. In multivariate regression analyses the lag phase remained significant in all tested models. Our data suggest that a short lag phase of LDL oxidation might be an independent risk factor of CAD.
Vitamin E/Lipid Peroxide Ratio and Susceptibility of LDL to Oxidative Modification in Non–Insulin-Dependent Diabetes Mellitus
Authors: Yoshida Hiroshi , Ishikawa Toshitsugu , Nakamura Haruo
Published: June 2011

Abstract
The presence of conventional risk factors cannot sufficiently account for the excess risk of atherosclerosis in patients with non–insulin-dependent diabetes mellitus (NIDDM). Oxidative modification of LDL has been implicated in the pathogenesis of coronary atherosclerosis. Thirty-five patients with NIDDM, 20 nondiabetic, hypertriglyceridemic subjects (HTG-control), and 21 diabetic, normotriglyceridemic subjects (NTG-control) were enrolled in this study. Oxidative susceptibility of LDL was determined by monitoring formation of conjugated dienes. Mean lag time of LDL oxidation and vitamin E/lipid peroxide of LDL was lower in patients with NIDDM (43.2±3.9 minutes and 1.6±1.3) than in HTG-control (48.8±3.2 minutes and 2.3±1.2, respectively) and NTG-control subjects (54.2±6.1 minutes and 3.0±1.8, respectively). Mean LDL particle size in patients with NIDDM and HTG-control subjects (24.4±0.9 and 24.7±0.7 nm, respectively) was smaller than in NTG-control subjects (25.9±1.0 nm). Multiple stepwise regression analyses ascertained that the vitamin E/lipid peroxide of LDL is a major determinant of LDL oxidation lag time. These results suggest that LDL in patients with NIDDM is more susceptible to oxidative modification primarily because of a reduced level of vitamin E/lipid peroxide of LDL. The enhanced susceptibility of LDL to oxidation may be a pivotal factor underlying the increased incidence of vascular disease in patients with NIDDM.
Relationship of LDL Size to Insulin Sensitivity in Normoglycemic Men
Authors: Mykkänen Leena , Haffner Steven M. , Rainwater David L. , Karhapää Pauli , Miettinen Heikki , Laakso Markku
Published: June 2011

Abstract
A preponderance of small, dense LDL has been suggested to be more atherogenic than larger, more buoyant LDL. Although several studies have suggested associations of small, dense LDL with hyperinsulinemia, few data are available on the relation of small, dense LDL to insulin resistance. We examined the association of LDL particle size determined by gradient gel electrophoresis with the rates of whole-body glu-cose uptake (WBGU) as determined by the hyperinsulinemic euglycemic clamp with indirect calorimetry in 87 Finnish normoglycemic men. LDL size was significantly positively correlated with the rates of WBGU (overall,
r
=.31,
P
<.01; oxidative,
r
=.23,
P
<.05; and nonoxidative,
r
=.31,
P
<.01). Rates of WBGU were also significantly lower in subjects with small LDL particles (≤26.0 nm) compared with those in sub-jects with larger LDL particles (>26.0 nm). This relation was not explained by obesity. Serum triglyceride concentrations were found to significantly affect the relationship of LDL particle size to WBGU. Specifically, LDL size was correlated with the rates of WBGU in men with mildly elevated triglyceride levels but not in men with low triglyceride levels. Serum VLDL triglyceride concentration was a substantially stronger determinant of LDL size than were the rates of WBGU. WBGU was not significantly related to LDL size when adjusted for triglycerides. We conclude that a preponderance of small, dense LDL particles is associated with insulin resistance and that serum triglyceride concentration modifies this relationship.
In Vitro and In Situ Magnetic Resonance Imaging Signal Features of Atherosclerotic Plaque-Associated Lipids
Authors: Yuan Chun , Petty Christopher , O’Brien Kevin D. , Hatsukami Thomas S. , Eary Janet F. , Brown B. Greg
Published: June 2011

Abstract
The goal of this study was to evaluate magnetic resonance imaging (MRI) signal features of the different types of lipids found in human atherosclerotic plaques. A 1.5-T SIGNA scanner was used to acquire T1-, T2-, and proton density– weighted data at four different temperatures for individual lipids and lipid mixtures designed to replicate the proportions of lipids found in plaques. Individual lipids and lipid mixtures were scanned both in a test tube and after implantation in the media of normal porcine aortas. Each of the three broad classes of lipids (triglycerides, unesterified and esterified cholesterol, and phospholipids) had different and distinct MR signal patterns, which allowed discrimination of these classes of lipids in vitro. Further, lipid implantation studies demonstrated that these distinct MR signal patterns could be used to readily distinguish each lipid type from surrounding porcine aortic media. MR signals from lipid mixtures demonstrated marked regional heterogeneity, similar to the heterogeneous lipid distribution characteristic of human atherosclerotic plaques. In summary, MR signals from lipid mixtures that mimic plaque lipid proportions can be detected at body temperature, especially in those mixtures with an increased percentage of cholesteryl esters. These studies raise the possibility that with further advances in technology, MRI may become a useful tool for determining the lipid content and composition of human atherosclerotic plaques in vivo.
Antiatherogenic Effect of Estrogen Abolished by Balloon Catheter Injury in Cholesterol-Clamped Rabbits
Authors: Holm Pernille , Stender Steen , Andersen Henrik õ. , Hansen Birgit F. , Nordestgaard Børge G.
Published: June 2011

Abstract
The purpose of this study was to investigate the importance of an intact endothelial cell layer on the direct antiatherogenic effect of estrogen on the arterial wall. Thirty rabbits were bilaterally ovariectomized and subjected to mechanical injury of the endothelium by balloon catheterization of the upper thoracic aorta. Immediately after the operation, treatment was initiated with either 17β-estradiol or placebo given intramuscularly. All rabbits were clamped at a similar plasma cholesterol level from 1 week before the operation until the experiment was terminated 13 weeks later. In the undamaged aorta, ie, the aortic arch, the lower thoracic aorta, and the upper abdominal aorta, the estrogen-treated rabbits had one third (
P
=.06), one sixth (
P
=.002), and one seventh (
P
=.001), respectively, the accumulation of cholesterol of the placebo-treated rabbits. In the upper thoracic aorta that had been subjected to mechanical injury of the endothelium, however, aortic cholesterol accumulation was not significantly different between the two groups. Similar results were obtained by histological evaluation of the aortic tissues. Immunohistochemical staining with antibodies against macrophages, smooth muscle cells, and T lymphocytes revealed no significant differences in the intimal distribution of cells between estrogen- and placebo-treated rabbits, except for a higher number of T lymphocytes per unit intimal area of the undamaged aortic arch (
P
<.0005) in the estrogen-treated-rabbits than the placebo-treated rabbits. This is the first study to demonstrate that the antiatherogenic effect of estrogen is abolished by balloon catheter injury in cholesterol-clamped rabbits. These results may indicate that an intact endothelial cell layer is crucial for the direct antiatherogenic effect of estrogen on the arterial wall.
Atorvastatin: An Effective Lipid-Modifying Agent in Familial Hypercholesterolemia
Authors: Marais A. David , Firth Jean C. , Bateman Mary E. , Byrnes Pam , Martens Candice , Mountney Jean
Published: June 2011

Abstract
Hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are the drugs of choice in heterozygous familial hypercholesterolemia (FH), which has a high risk of ischemic heart disease. An open-label study was conducted to test the efficacy and safety of atorvastatin, a new synthetic HMG-CoA reductase inhibitor in proven FH. After a 4-week placebo phase, 22 subjects were randomized to either 80 mg atorvastatin at night (n=11) or 40 mg twice a day for 6 weeks. The two dosage groups were well matched and had no difference in lipoprotein responses. After 6 weeks, the LDL cholesterol concentration was reduced by 57%, from 8.16±1.15 to 3.53±0.99 mmol/L (
P
<.001). The total cholesterol concentration decreased from 9.90±1.32 to 5.43 mmol/L (
P
<.001). HDL cholesterol concentration increased from 1.19±0.31 to 1.49±0.43 mmol/L (
P
<.001). Triglyceride concentrations decreased from 1.34±0.66 to 0.88±0.36 mmol/L (
P
<.01). Three subjects had single, transient increases of serum transaminase of up to twice the upper limit of normal. Apolipoprotein B concentration decreased significantly by 42%. Changes in apolipoproteins AI and (a) were not statistically significant. Nondenaturing gradient gel electrophoresis revealed increases in the size of smaller LDL particles in four subjects. Plasma fibrinogen concentration increased by 44%. The drug was well tolerated. One subject withdrew for personal reasons. Ator- vastatin is a powerful and safe lipid-modifying agent for LDL cholesterol; it also modifies HDL cholesterol and triglyceride concentrations, and may suffice as a single agent for many subjects with heterozygous FH.
Intracellular Calcium Mobilization Suppresses the TNF-α–Stimulated Synthesis of PAI-1 in Human Endothelial Cells
Authors: Peiretti Franck , Alessi Marie-Christine , Henry Mireille , Anfosso Francine , Juhan-Vague Irène , Nalbone Gilles
Published: June 2011

AbstractWe investigated in human umbilical vein endothelial cells (HUVECs) the interaction between the signaling pathways triggered by calcium mobilization and those affected by human recombinant tumor necrosis factor-α (TNF) on the expression of type-1 plasminogen activator inhibitor (PAI-1). Calcium ionophore A23187 alone exerted a modest increase (50%) on PAI-1 synthesis. TNF alone increased PAI-1 accumulation in the culture medium in a time- and dose-dependent fashion, but this increase was abolished when A23187 was added simultaneously with TNF. The downregulating effect of A23187 was not the result of impaired protein secretion, proteolysis, cytotoxicity, or an apoptotic process. A23187 did not decrease the TNF-enhanced PAI-1 mRNA level but did provoke a significant shift in the distribution pattern of PAI-1 transcripts by increasing the 2.3-kb relative to the 3.2-kb form. Comparable inhibitory effects on PAI-1 protein synthesis were observed when A23187 was added 7 hours after the onset of TNF stimulation, strongly suggesting a posttranscriptional inhibitory action of calcium signaling on TNF-stimulated PAI-1 synthesis. However, treatment with actinomycin D showed that PAI-1 mRNA stability was not altered by the various treatments. Chelation of extracellular calcium by EGTA did not prevent the A23187-induced inhibition of TNF-stimulated PAI-1 protein synthesis, emphasizing the role of internal calcium stores in the inhibition of PAI-1 synthesis. Sucrose gradient fractionation of cell lysates revealed that regardless of which treatment was used, both PAI-1 mRNA transcripts exhibited similar sedimentation profiles in the actively translating polysomal pool, suggesting that the A23187-induced shift had no functional consequence on translation. However, in TNF-stimulated cells, A23187 induced a higher proportion of PAI-1 mRNAs that sedimented in fractions corresponding to less dense polysomes, a phenomenon that usually reflects a slower initiation rate during mRNA translation. A23187 also abolished the increase in PAI-1 synthesis induced by recombinant human interleukin 1β, and thapsigargin exerted effects comparable to those of A23187 on PAI-1 synthesis in TNF-stimulated cells. It is proposed that in HUVECs, the A23187-induced release of calcium from endoplasmic stores suppresses at the translational level the increase in PAI-1 synthesis triggered by proinflammatory cytokines.
Induction of Cyclooxygenase-2 in Human Saphenous Vein and Internal Mammary Artery
Authors: Bishop-Bailey David , Pepper John R. , Haddad E.-B. , Newton Robert , Larkin Simon W. , Mitchell Jane A.
Published: June 2011

AbstractWithin vessels, cyclooxygenase (COX) is expressed constitutively (COX-1) in endothelial cells where its production of prostacyclin is thought to contribute to the maintenance of vascular integrity. Recently, a novel isoform of COX, COX-2, has been described that is induced in animal arterial vessels after physical damage or exposure to proinflammatory cytokines. However, induction of COX-2 in human vessels has not been characterized. Moreover, the relative ability of arteries and veins to express COX-2 has not been addressed. Thus, we have compared the ability of segments of human saphenous vein and internal mammary artery, obtained from the same patient, to express COX-2 activity and mRNA after organ culture in the presence and absence of interleukin-1β. COX-2 metabolites, measured by radioimmunoassay, were released by both the internal mammary artery and saphenous vein in the following rank order: prostaglandin E2≥prostacyclin thromboxane A2. Inclusion of interleukin-1β in the culture medium increased the release of prostanoids by the saphenous vein but not by the internal mammary artery. However, the selective COX-2 inhibitor NS-398 significantly attenuated prostacyclin release from both tissues. Northern blot analysis showed no detectable COX-2 mRNA in freshly prepared saphenous vein or internal mammary artery. In contrast, after 48 hours in organ culture, low levels of COX-2 mRNA were detected in both internal mammary artery and saphenous vein, an effect that was greatly increased by interleukin-1β. These observations show that COX-2 is induced in human saphenous vein and internal mammary artery and suggest that this may occur in humans after coronary artery bypass graft surgery. The induction of COX-2 and subsequent release of prostacyclin may represent an endogenous defense mechanism against endothelial damage incurred during surgical preparation of these vessels for bypass.
Repeated Balloon Injury of Rat Aorta
Authors: Capron Loïc , Jarnet Jacqueline , Heudes Didier , Joseph-Monrose Daniel , Bruneval Patrick
Published: June 2011

Abstract
Repeated arterial injury, because it challenges already activated cells, may elicit a reaction that differs from that provoked by a single injury. We compared the response of rat aorta to single and double balloon injury and tested the inhibitory effect of heparin in both situations. For repeated injury, the first and second lesions were induced 3 weeks apart. Two weeks after repeated injury, the neointima that existed from the first lesion had expanded, with significant increases in intima-media wet weight and its DNA and elastin content and in the intima-to-media (I/M) thickness ratio. Two days after repeated injury, the expression of proliferating cell nuclear antigen (PCNA) was enhanced in both the media and the intima, indicating that cells from both layers are involved in the aortic response to a second lesion. As established previously, treatment with heparin (continuous intravenous administration, 50 IU/kg · h
−1
) almost totally suppressed the response to single injury. However, heparin only attenuated the response to repeated injury, with a partial decrease in intima-media wet weight and its DNA and elastin content and in I/M thickness ratio. PCNA labeling showed that heparin inhibited the proliferative activity in medial cells much more strongly than in intimal cells. In conclusion, repeated aortic injury elicits a reaction of both the media and preexisting neointima. In this mixed response, neointimal smooth muscle cells are less sensitive than medial cells to inhibition by heparin, which results in a weakened effect of the drug on the fibromuscular reaction.
Effects of Short-term Exercise on Female Platelet Function During Different Phases of the Menstrual Cycle
Authors: Wang Jong-Shyan , Jen Chauying J. , Lee Hwei-Ling , Chen Hsiun-ing
Published: June 2011

AbstractPrevious studies have shown that premenopausal women have a low incidence of cardiovascular diseases, and that acute exercise affects male platelet function in an intensity-dependent manner. To investigate whether acute exercise affects female platelet function differently from males, sixteen sedentary women in the midfollicular phase or midluteal phase received strenuous or moderate exercise on a bicycle ergometer. Before and immediately after exercise, platelet adhesiveness, adenosine diphosphate-induced platelet aggregation and intracellular calcium concentration elevation, platelet cAMP and cGMP contents, urinary 11-dehydro-TXB2and 6-keto-prostaglandin F1α levels, and plasma nitric oxide metabolite level were determined. Our results showed no differences in exercise performance and in resting platelet function between two menstrual phases, with little change in urinary eicosanoid metabolites and platelet cAMP levels under all experimental conditions. In addition, for women in the midfollicular phase, (1) strenuous exercise increased platelet adhesiveness, adenosine-diphosphate-induced platelet aggregation, and intracellular calcium concentration elevation, whereas moderate exercise suppressed them; (2) moderate exercise enhanced plasma nitric oxide metabolite and platelet cGMP levels. In contrast, none of these platelet functions was affected by acute exercise in the midluteal phase. Therefore, we conclude that acute exercise affects female platelet function in an intensity-dependent manner in the midfollicular phase but not in the midluteal phase. The irresponsiveness of platelets to acute exercise in the luteal phase may partially explain why premenopausal women have a lower incidence of cardiovascular diseases than men.
Fatty Streak Formation in Fat-Fed Mice Expressing Human Copper-Zinc Superoxide Dismutase
Authors: Tribble Diane L. , Gong Elaine L. , Leeuwenburgh Christiaan , Heinecke Jay W. , Carlson Elaine L. , Verstuyft Judy G. , Epstein Charles J.
Published: June 2011

AbstractStudies in vitro have shown that copper-zinc superoxide dismutase (CuZn-SOD) inhibits a number of events putatively involved in atherogenesis, including cell-mediated oxidation of LDL. To investigate whether increased activity of CuZn-SOD reduces atherogenesis in vivo, we examined diet-induced fatty streak formation in CuZn-SOD transgenic mice (n=24) as compared with their nontransgenic littermates (n=28). Transgenic animals were originally created by introduction of anEcoRI-BamHI human genomic DNA fragment containing the CuZn-SOD gene and its regulatory elements into B6SJL zygotes. For the current studies, the transgene was bred for 12 generations into the atherosclerosis-susceptible C57BL/6 background. Animals were fed atherogenic diets (15% fat, 1.25% cholesterol, 0.5% Na cholate) starting at 10 weeks of age and extending for 18 weeks. At the end of the diet period, aortic SOD activity was two-fold higher in transgenics than nontransgenics (mean±SE: 46.7±5.8 versus 20.1±2.4 units/mg of protein,P<.001). Levels of protein-bound amino acid oxidation products (meta-,ortho-, and dityrosine) were either similar or lower in aorta and heart from transgenics as compared with nontransgenics, suggesting that amplification of CuZn-SOD activity above the normal complement had modest inhibitory effects on basal oxidative stress in these tissues. CuZn-SOD overexpression did not reduce the extent of lesion development as analyzed by quantitative lipid staining of serial sections of the proximal aorta; mean lesion areas (±SE) were 997±478 and 943±221 μ2in transgenics and nontransgenics, respectively. Notably, the range of values for lesion area was 2.2-fold greater in transgenics (0-8403 versus 0-3868 μ2in nontransgenics). Moreover, within this group, lesion area showed a significant positive correlation with SOD activity (r=.611,P<.03). These results do not support an antiatherogenic effect of CuZn-SOD over expression, and the possibility that high tissue SOD activity may potentiate atherogenesis in fat-fed atherosclerosis-susceptible mice.
Effects of Estrus Cycle, Ovariectomy, and Treatment with Estrogen, Tamoxifen, and Progesterone on Apolipoprotein(a) Gene Expression in Transgenic Mice
Authors: Zysow Bernice R. , Kauser Katalin , Lawn Richard M. , Rubanyi Gabor M.
Published: June 2011

Abstract
Plasma levels of lipoprotein(a) (Lp(a)), are regulated by the synthetic rate of apolipoprotein(a) (apo(a)), a major protein component of this atherogenic lipoprotein. Exogenously administered sex steroid hormones are potent regulators of plasma Lp(a) concentrations. We utilized a recently developed apo(a) yeast artificial chromosome (YAC) transgenic mouse model to study the effects of ovariectomy, estrus cycle, and exogenous administration of ethinyl-estradiol, the partial estrogen receptor agonist, tamoxifen, and progesterone on circulating apo(a) plasma levels. Analysis of liver RNA revealed that estrogen and tamoxifen exerts their plasma apo(a) lowering effect at the level of apo(a) mRNA. This action of estrogen and tamoxifen may contribute to their antiatherosclerotic and cardiovascular protective effect.
Regulation of Lipoprotein Metabolism by Thiazolidinediones Occurs through a Distinct but Complementary Mechanism Relative to Fibrates
Authors: Lefebvre Anne-Marie , Peinado-Onsurbe Julia , Leitersdorf Iris , Briggs Michael R. , Paterniti James R. , Fruchart Jean-Charles , Fievet Catherine , Auwerx Johan , Staels Bart
Published: June 2011

Abstract
Thiazolidinediones are antidiabetic agents, which not only improve glucose metabolism but also reduce blood triglyceride concentrations. These compounds are synthetic ligands for PPARγ, a transcription factor belonging to the nuclear receptor subfamily of PPARs, which are important transcriptional regulators of lipid and lipoprotein metabolism. The goal of this study was to evaluate the influence of a potent thiazolidinedione,
BRL49653
, on serum lipoproteins and to determine whether its lipid-lowering effects are mediated by changes in the expression of key genes implicated in lipoprotein metabolism. Treatment of normal rats for 7 days with
BRL49653
decreased serum triglycerides in a dose-dependent fashion without affecting serum total and HDL cholesterol and apolipoprotein (apo) A-I and apo A-II concentrations. The decrease in triglyceride concentrations after
BRL49653
was mainly due to a reduction of the amount of VLDL particles of unchanged lipid and apo composition.
BRL49653
treatment did not change triglyceride production in vivo as analyzed by injection of Triton WR-1339, indicating a primary action on triglyceride catabolism. Analysis of the influence of
BRL49653
on the expression of LPL and apo C-III, two key players in triglyceride catabolism, showed a dose-dependent increase in mRNA levels and activity of LPL in epididymal adipose tissue, whereas liver apo C-III mRNA levels remained constant. Furthermore, addition of
BRL49653
to primary cultures of differentiated adipocytes increased LPL mRNA levels, indicating a direct action of the drug on the adipocyte. Simultaneous administration of
BRL49653
and fenofibrate, a hypolipidemic drug that acts primarily on liver through activation of PPARα both decreased liver apo C-III and increased adipose tissue LPL mRNA levels, resulting in a more pronounced lowering of serum triglycerides than each drug alone. In conclusion, both fibrates and thiazolidinediones exert a hypotriglyceridemic effect. While fibrates act primarily on the liver by decreasing apo C-III production,
BRL49653
acts primarily on adipose tissue by increasing lipolysis through the induction of LPL expression. Drugs combining both PPARα and γ activation potential should therefore display a more efficient hypotriglyceridemic activity than either compound alone and may provide a rationale for improved therapy for elevated triglycerides.
Dietary Fat Clearance in Normal Subjects Is Modulated by Genetic Variation at the Apolipoprotein B Gene Locus
Authors: Lopez-Miranda J. , Ordovas J.M. , Ostos M.A. , Marin C. , Jansen S. , Salas J. , Blanco-Molina A. , Jimenez-Pereperez J.A. , Lopez-Segura F. , Perez-Jimenez F.
Published: June 2011

AbstractApolipoprotein B (apo B) plays a dominant role in cholesterol homeostasis. Several polymorphic sites within or adjacent to the gene locus for apo B have been detected. The X+ allele (XbaI restriction site present) of the XbaI restriction fragment polymorphism on the apo B gene has been found in some studies to be associated with higher serum cholesterol and/or triglyceride levels and with greater dietary response. The present study was designed to evaluate whether the apo B XbaI polymorphism was associated with the interindividual variability observed during postprandial lipemia. Fifty-one healthy young male volunteers [20 X−/X− (X−), and 31 X+/X− or X+/X+ (X+)], homozygotes for the apo E3 allele, were subjected to a vitamin A-fat load test. Subjects with the X− genotype had significantly greater retinyl palmitate (RP) and apo B-48 postprandial responses on both the large and the small TRL lipoprotein fractions compared with X+ subjects. In summary, subjects with the X−/X− genotype at the apo B locus have a greater postprandial response than X+ subjects. These differences observed in postprandial lipoprotein metabolism could explain some of the reported associations of this polymorphism to coronary heart disease risk.