bluuebunny/crossref_metadata_2025 huggingface dataset:
Arterial Elastase Activity After Balloon Angioplasty and Effects of Elafin, an Elastase Inhibitor
Authors: Barolet Alan W. , Nili Nafiseh , Cheema Asim , Robinson Ranga , Natarajan Madhu K. , O’Blenes Stacy , Li Jing , Eskandarian Mohammad R. , Sparkes John , Rabinovitch Marlene , Strauss Bradley H.
Published: September 2007

Increased proteolytic activity may be a factor in intimal hyperplasia after balloon angioplasty (BA). The objectives of this study were to assess elastase activity after BA in a rabbit arterial double-injury model and the effects of elastase inhibition. Elastase activity increased immediately after BA, reached an 8-fold peak at 1 week, and declined to baseline levels by 4 weeks. Elastin zymography showed that the elastase activity was associated predominantly with a molecular mass of 25 kDa. Elastase activity was significantly inhibited in vitro by elafin and phenylmethylsulfonyl fluoride, selective inhibitors of serine elastases. A second group of animals was transfected after BA with a plasmid containing the cDNA for either elafin or a control (chloramphenicol acetyltransferase, CAT) construct by using a hemagglutinating virus of Japan–liposome transfection technique. Arterial segments were obtained at 48 hours, 1 week, and 4 weeks to assess transgene expression, arterial wall elastase activity, and intimal cross-sectional area, respectively. Elafin transgene expression was evident at 48 hours and resulted in a significant (80%) inhibition of elastase activity compared with chloramphenicol acetyltransferase–transfected arteries. There was a 43% reduction in intimal cross-sectional area in elafin-transfected arteries (0.28±0.22 versus 0.16±0.07 mm
2
for CAT-transfected versus elafin-transfected arteries, respectively;
P
<0.05). These data suggest that an early increase in serine elastase activity after BA contributes to intimal hyperplasia. Serine elastase inhibition may be a potential therapeutic approach to inhibit intimal hyperplasia.
Molecular Analysis of Apo(a) Fragmentation in Polygenic Hypercholesterolemia
Authors: Gonbert Sophie , Saint-Jore Bruno , Giral Philippe , Doucet Chantal , Chapman John , Thillet Joëlle
Published: September 2007

Hypercholesterolemia is frequently associated with elevated Lp(a) levels, an independent risk factor for coronary, cerebrovascular, and peripheral vascular disease. A portion of apolipoprotein(a) [apo(a)] circulates as a series of fragments derived from the N-terminal region of apo(a). The relationship of elevated lipoprotein(a) [Lp(a)] levels to those of circulating apo(a) fragments in polygenic hypercholesterolemia is indeterminate. Therefore, plasma Lp(a) and plasma and urinary apo(a) fragment levels were measured by ELISA in 82 patients with polygenic type IIa hypercholesterolemia (low density lipoprotein cholesterol ≥4.13 mmol/L and triglycerides <2.24 mmol/L) and in 90 normolipidemic subjects. Lp(a) levels were significantly elevated in patients compared with control subjects (0.35±0.4 and 0.24±0.31 mg/mL, respectively; median 0.13 and 0.11 mg/mL, respectively;
P
=0.039), although apo(a) isoform distribution did not differ. Patients displayed significantly higher plasma and urinary apo(a) fragment levels than did control subjects (respective values were as follows: 4.97±5.51 and 2.15±2.57 [median 2.85 and 1.17] μg/mL in plasma,
P
<0.0001; 75±86 and 40±57 [median 38 and 17] ng/mg urinary creatinine in urine,
P
<0.0001). The ratio of plasma apo(a) fragments to Lp(a) levels was also significantly higher in patients than in control subjects (1.93±1.5% and 1.75±2.36%, respectively;
P
<0.0001). We conclude that increased plasma Lp(a) levels in polygenic hypercholesterolemia are associated with elevated circulating levels of apo(a) fragments but that this increase is not due to decreased renal clearance of apo(a) fragments. Furthermore, we identified a new pattern of apo(a) fragmentation characterized by the predominance of a fragment band whose size was related to that of the parent apo(a) isoform and that was superimposed on the series of fragments described previously by Mooser et al (
J Clin Invest
. 1996; 98:2414–2424). This new pattern was associated with small apo(a) isoforms and did not discriminate between hypercholesterolemic and normal subjects. However, this new apo(a) fragment pattern may constitute a novel marker for cardiovascular risk.
Plasminogen Activator Inhibitor Type 1 Is Increased in the Arterial Wall of Type II Diabetic Subjects
Authors: Pandolfi A. , Cetrullo D. , Polishuck R. , Alberta M.M. , Calafiore A. , Pellegrini G. , Vitacolonna E. , Capani F. , Consoli A.
Published: September 2007

Plasma plasminogen activator inhibitor type 1 (PAI-1) increases in diabetes, and this might contribute to decreased fibrinolysis and accelerated atherosclerosis. Increased PAI-1 levels in the vessel wall could decrease local fibrinolysis and elevate thrombus formation and the unfavorable evolution of atherosclerotic plaques. High glucose increases PAI-1 synthesis in arterial wall cells in culture, and aortic wall PAI-1 levels have been found to be elevated in diabetic animals. However, arterial wall PAI-1 levels have not been investigated in diabetic subjects. Therefore, the aim of this study was to determine the effect of diabetes on PAI-1 levels in the arterial wall. Blood samples and small tissue specimens from the mammary artery were obtained from 11 diabetic and 10 nondiabetic subjects who underwent coronary artery bypass graft surgery. PAI-1 antigen localization in the arterial wall was obtained by immunohistochemistry and was read by laser scanning confocal microscopy; plasma fibrinolytic activity was measured by lysis of fibrin plates; and PAI-1 activity was assessed by a chromogenic method. PAI-1–related immunofluorescence was increased in the arterial wall of diabetic patients, whereas plasma fibrinolysis was reduced. These data provide evidence that diabetes is associated with increased PAI-1 in the arterial wall. This might be an important factor for increased cardiovascular risk and unfavorable plaque evolution in diabetes.
Raloxifene-Mediated Increase in Matrix Metalloproteinase-1 Production by Activated Monocytes
Authors: Ardans Jeanette A. , Blum Arnon , Mangan Paul R. , Wientroub Shlomo , Cannon Richard O. , Wahl Larry M.
Published: September 2007

Matrix metalloproteinases (MMPs), proteolytic enzymes produced by monocytes, may contribute to atherosclerotic arterial wall remodeling and to plaque rupture. Because estrogen influences the synthesis of MMPs, we examined the effect of raloxifene, a selective estrogen receptor modulator, on monocyte MMP production. Human primary blood monocytes treated with raloxifene (10 μmol/L) in the presence of lipopolysaccharide (LPS) or tumor necrosis factor-α and granulocyte-macrophage colony–stimulating factor induced a 2- to 3-fold increase in MMP-1 production by monocytes. The enhancement of MMP-1 production by raloxifene in LPS-activated monocytes occurred through a cyclooxygenase-2– and prostaglandin E
2
–independent mechanism. Additionally, compared with monocytes acquired during the placebo phase, peripheral blood monocytes from 5 of 6 healthy postmenopausal women treated with raloxifene (60 mg daily for 1 month) in a clinical trial produced significantly higher levels of MMP-1 when the monocytes were activated with LPS. Furthermore, serum obtained during the raloxifene phase from 4 of these subjects, when added to control monocytes, significantly enhanced LPS-induced MMP-1 production compared with that from serum obtained during the placebo phase. In summary, raloxifene increases the production of MMP-1 in activated monocytes; this effect may be favorable in atherosclerotic arterial wall remodeling but unfavorable for plaque stability.
Is the Emperor Wearing Clothes?
Authors: Heinecke Jay W.
Published: September 2007

A wealth of evidence indicates that oxidized low density lipoprotein (LDL) may be of central importance in animal models of atherogenesis. In recent clinical trials, however, dietary vitamin E supplements have not consistently prevented cardiac events in humans with established coronary artery disease. Such mixed results have led many to question the role of LDL oxidation in human atherosclerosis, although this interpretation assumes that the doses of vitamin E used in the studies inhibited lipid oxidation in vivo. In fact, there is remarkably little evidence indicating that those particular regimens effectively inhibit lipid peroxidation in healthy humans. Moreover, evidence of increased oxidative stress was not a criterion for inclusion in the trials; therefore, vitamin E may have benefited only a subset of the participants. These uncertainties raise doubts about the ability of vitamin E to augment antioxidant defense mechanisms in vivo and leave many questions about LDL oxidation and atherosclerosis unanswered.
CD11b/CD18 Mediates Production of Reactive Oxygen Species by Mouse and Human Macrophages Adherent to Matrixes Containing Oxidized LDL
Authors: Husemann Jens , Obstfeld Amrom , Febbraio Maria , Kodama Tatsuhiko , Silverstein Samuel C.
Published: September 2007

Production of reactive oxygen species (ROS) and other proinflammatory substances by macrophages adherent to matrix proteins that contain or have been modified by oxidized LDL (oxLDL) may play an important role in atherogenesis. In vitro, human macrophages adhere to matrixes containing oxLDL via scavenger receptors and are signaled to produce ROS partly by interactions of the class B scavenger receptor (SR-B) CD36 with ligands on the matrix. In this report, we show that macrophages from mice genetically deficient in SR-A or CD36 adhered equally as well and produced equal amounts of ROS on interaction with matrix-associated oxLDL. In contrast, macrophages from mice genetically deficient in the CD18 chain of β
2
-integrins produced insignificant amounts of ROS on interaction with oxLDL-containing matrixes, even though they adhered to these matrixes as efficiently as did macrophages from wild-type mice. Antibodies against CD18, CD11b, or EDTA, the last of which chelates divalent cations required for integrin function, had no effect on adhesion of normal mouse or human macrophages to matrixes containing oxLDL but almost completely inhibited ROS production by macrophages adherent to this matrix. Thus, CD11b/CD18 plays an important role in regulating production of ROS by mouse and human macrophages adherent to matrixes containing oxLDL. It may play a hitherto-unsuspected role in regulating macrophage signaling pathways involved in inflammation and atherogenesis.
Human Blood-Derived Macrophages Induce Apoptosis in Human Plaque-Derived Vascular Smooth Muscle Cells by Fas-Ligand/Fas Interactions
Authors: Boyle Joseph J. , Bowyer David E. , Weissberg Peter L. , Bennett Martin R.
Published: September 2007

Human atherosclerotic plaques that rupture are characterized by relatively low vascular smooth muscle cell (VSMC) and high inflammatory cell contents. Ruptured plaques also contain higher numbers of apoptotic VSMCs than do stable lesions, suggesting that VSMC apoptosis may promote plaque rupture. We examined the ability of human monocytes/macrophages to induce apoptosis of VSMCs derived from human carotid plaque, aortic media, and coronary media. Macrophages, but not T lymphocytes, induced a dose-dependent apoptosis of VSMCs, which required monocyte maturation to macrophages and direct cell-cell contact/proximity. VSMC apoptosis was inhibited by neutralizing antibodies to Fas-ligand (Fas-L) or an Fas-Fc fusion protein, indicating the requirement for membrane-bound Fas and Fas-L. Monocyte maturation was associated with increased surface expression of Fas-L, coincident with the onset of cytotoxicity. VSMCs expressed surface Fas, which was increased in plaque VSMCs, and plaque VSMCs also underwent Fas-induced apoptosis. We conclude that human macrophages potently induce human VSMC apoptosis, which requires direct cell-cell interactions and is in part dependent on Fas/Fas-L interactions. Macrophage-induced VSMC apoptosis may therefore directly promote plaque rupture.
Interleukin-6 Gene −174G>C and −572G>C Promoter Polymorphisms Are Strong Predictors of Plasma Interleukin-6 Levels After Coronary Artery Bypass Surgery
Authors: Brull D.J. , Montgomery H.E. , Sanders J. , Dhamrait S. , Luong L. , Rumley A. , Lowe G.D.O. , Humphries S.E.
Published: September 2007

Interleukin-6 (IL-6) synthesized in response to diverse stimuli may play an important role in bridging the inflammatory and atherosclerotic processes. The acute-phase response after coronary artery bypass graft surgery (CABG) is associated with the induction and release of cytokines, such as IL-6. We have examined the effect of common polymorphisms in the IL-6 gene promoter (−174G>C, −572G>C, and −597G>A) on IL-6 levels after elective CABG. DNA extracted from the peripheral blood of 127 patients was amplified by polymerase chain reaction. IL-6 genotypes were resolved by gel electrophoresis after restriction enzyme digestion. Serum IL-6 was measured before surgery and in serial samples at 6, 24, 48, and 72 hours after CABG. Genotype distribution was as expected for a population in Hardy-Weinberg equilibrium for all polymorphisms. Rare allele frequencies (±95% CIs) were similar to those reported previously: −597A 0.36 (0.30 to 0.42), −572C 0.07 (0.04 to 0.10), and −174C 0.37 (0.31 to 0.43). The −174G>C and −597G>A genotypes were in strong allelic association (Δ=0.97,
P
<0.001). Baseline IL-6 levels did not significantly differ between patients with different genotypes for any polymorphism. However, 6 hours after CABG, peak IL-6 levels were significantly higher (
P
=0.03) in carriers of the −572C allele than in those of the −572GG genotype (355±67 versus 216±13 pg/mL, respectively) and in those with genotype −174CC compared with −174G allele carriers (287±31 versus 227±15 pg/mL, respectively;
P
=0.04). These effects remained statistically significant after adjusting for possible confounders, including age, sex, smoking, duration of cardiopulmonary bypass, aortic cross-clamp time, and total duration of surgery. These data demonstrate that IL-6 promoter polymorphisms influence peak IL-6 production after CABG, suggesting that these polymorphisms, which are functional in vitro, are also functional in vivo, suggesting a genetic influence on IL-6 levels after acute severe injury.
Markedly Elevated Lipid Transfer Inhibitor Protein in Hypercholesterolemic Subjects Is Mitigated by Plasma Triglyceride Levels
Authors: Morton Richard E. , Nunes Valéria , Izem Lahoucine , Quintão Eder
Published: September 2007

Lipid transfer inhibitor protein (LTIP, apolipoprotein F) regulates the interaction of cholesteryl ester transfer protein (CETP) with lipoproteins and is postulated to enhance the ability of CETP to stimulate reverse cholesterol transport. The factors that regulate LTIP levels and control its biosynthesis are unknown. Here, we demonstrate that plasma LTIP is dramatically increased (3-fold) in hypercholesterolemic subjects with normal to mildly elevated plasma triglyceride (TG) levels compared with control subjects. LTIP in these subjects is not correlated with the extent of hypercholesterolemia or with low density lipoprotein (LDL), high density lipoprotein, or CETP levels. However, unlike CETP, LTIP levels correlate negatively with plasma TG levels. This association does not appear to reflect decreased LTIP synthesis, inasmuch as conditions that stimulate TG synthesis and secretion (200 μmol/L oleate) do not reduce LTIP secretion by SW872 or Caco-2 cells. In contrast, native or acetyl LDL stimulates LTIP secretion 2-fold. Importantly, although plasma LTIP typically resides on LDL, up to 25% of LTIP is bound to very low density lipoprotein when this lipoprotein is enriched in cholesteryl esters, as occurs in hypercholesterolemia. In summary, LTIP levels are markedly elevated by hypercholesterolemia; however, plasma TG levels attenuate this response. We hypothesize that this arises from an increased association of LTIP with very low density lipoprotein, leading to a more rapid clearance of the inhibitor from circulation.
Allele-Specific Regulation of Matrix Metalloproteinase-7 Promoter Activity Is Associated With Coronary Artery Luminal Dimensions Among Hypercholesterolemic Patients
Authors: Jormsjö Sofia , Whatling Carl , Walter Dirk H. , Zeiher Andreas M. , Hamsten Anders , Eriksson Per
Published: September 2007

An enhanced expression of matrix metalloproteinase (MMP)-7 has previously been demonstrated in atherosclerotic and aneurysmal tissue. Because perturbed regulation of MMP-7 may influence the development of these diseases, we searched the MMP-7 promoter for functional polymorphisms. An A to G substitution at position −181 (−181 A/G) and a C to T substitution at position −153 (−153 C/T) with frequencies of 0.50 and 0.10, respectively, were identified. Allele-specific associations were studied in 350 patients undergoing percutaneous transluminal coronary angioplasty. Hypercholesterolemic patients carrying the −181G allele or the −153T allele had smaller reference luminal diameters before percutaneous transluminal coronary angioplasty. Reverse transcription–polymerase chain reaction demonstrated that expression of MMP-7 was confined to differentiated U937 cells. Northern blot analysis could not detect an effect of native or oxidatively modified low density lipoprotein on MMP-7 expression. Thus, the limitation of allele-specific effects on vessel wall remodeling to hypercholesterolemic patients may be secondary to lipid-mediated accumulation of MMP-7–expressing monocyte-derived macrophages within the vessel wall. Both polymorphisms influenced the binding of nuclear proteins. Furthermore, in transient transfection studies, the combination of the 2 rare alleles conferred an increased promoter activity. In conclusion, the present study identified and characterized 2 common polymorphisms in the promoter region of the MMP-7 gene that are functional in vitro and seem to influence coronary arterial dimensions in hypercholesterolemic patients with manifest coronary artery disease.
Angiogenesis, Vascular Endothelial Growth Factor and Platelet-Derived Growth Factor-BB Expression, Iron Deposition, and Oxidation-Specific Epitopes in Stented Human Coronary Arteries
Authors: Bräsen Jan Hinrich , Kivelä Antti , Röser Kerstin , Rissanen Tuomas T. , Niemi Mari , Luft Friedrich C. , Donath Karl , Ylä-Herttuala Seppo
Published: September 2007

Pathogenesis of in-stent restenosis remains poorly understood because information from human histopathologic studies is scarce. We used an improved saw-grinding and cutting method on methacrylate-embedded samples containing metal stents, which allows in situ hybridization and immunohistochemical analysis of in-stent restenosis. Twenty-one samples were collected 3 hours to 3 years after stenting from 6 patients aged 36 to 81 years. Except in very early samples collected within hours after the stent deployment, neovascularization was present in all segments studied. At advanced stages, extensive neovascularization was located mainly at the luminal side of the stent struts and was only rarely accompanied by inflammatory cells. The neovessels colocalized with vascular endothelial growth factor (VEGF)-A mRNA and protein expression as well as with iron deposits and oxidation-specific epitopes, which imply the presence of chronic oxidative stress. VEGF-A expression was detected in the same areas containing macrophages, endothelial cells, and, to a lesser extent, smooth muscle cells, which also showed platelet-derived growth factor-BB expression. We conclude that in-stent restenosis features neovascularization, VEGF-A and platelet-derived growth factor-BB expression, and iron deposition, which is most probably derived from microhemorrhages. These mechanisms may play an important role in the development of neointimal thickening and could provide useful targets for the prevention and treatment of in-stent restenosis.
Biphasic Effects of 15-Deoxy-Δ
12,14
-Prostaglandin J
2
on Glutathione Induction and Apoptosis in Human Endothelial Cells
Authors: Levonen Anna-Liisa , Dickinson Dale A. , Moellering Douglas R. , Mulcahy R. Timothy , Forman Henry Jay , Darley-Usmar Victor M.
Published: September 2007

The lipid products derived from the cyclooxygenase pathway can have diverse and often contrasting effects on vascular cell function. Cyclopentenone prostaglandins (cyPGs), such as 15-deoxy-Δ
12,14
-prostaglandin-J
2
(15d-PGJ
2
), a peroxisome proliferator–activated receptor-γ (PPARγ) agonist, have been reported to cause endothelial cell apoptosis, yet in other cell types, cyPGs induce cytoprotective mediators, such as heat shock proteins, heme oxygenase-1, and glutathione (GSH). Herein, we show in human endothelial cells that low micromolar concentrations of 15d-PGJ
2
enhance GSH-dependent cytoprotection through the upregulation of glutamate-cysteine ligase, the rate-limiting enzyme of GSH synthesis, as well as GSH reductase. The effect of 15d-PGJ
2
on GSH synthesis is attributable to the cyPG structure but is independent of PPAR, inasmuch as the other cyPGs, but not PPARγ or PPARα agonists, are able to increase GSH. The increase in cellular GSH is accompanied by abrogation of the proapoptotic effects of 4-hydroxynonenal, a product of lipid peroxidation present in atherosclerotic lesions. However, higher concentrations of 15d-PGJ
2
(10 μmol/L) cause endothelial cell apoptosis, which is further enhanced by depletion of cellular GSH by buthionine sulfoximine. We propose that the GSH-dependent cytoprotective pathways induced by 15d-PGJ
2
contribute to its antiatherogenic effects and that these pathways are distinct from those leading to apoptosis.
Thrombin Induces Interleukin-6 Expression Through the cAMP Response Element in Vascular Smooth Muscle Cells
Authors: Tokunou Tomotake , Ichiki Toshihiro , Takeda Kotaro , Funakoshi Yuko , Iino Naoko , Shimokawa Hiroaki , Egashira Kensuke , Takeshita Akira
Published: September 2007

The plasma level of interleukin-6 (IL-6) is elevated in patients with acute coronary syndromes and has prognostic value. Thrombin is a potent mitogen for vascular smooth muscle cells (VSMCs) and plays an important role in the progression of atherosclerosis. We examined the mechanism of thrombin-induced IL-6 expression in VSMCs. Thrombin induced IL-6 mRNA and protein expression in a dose-dependent manner. Pharmacological inhibition of extracellular signal-regulated protein kinase (ERK), p38 mitogen-activated protein kinase (MAPK), or epidermal growth factor receptor (EGF-R) suppressed the thrombin-induced IL-6 expression. Deletion and mutation analysis of the promoter region of the IL-6 gene by using luciferase as a reporter showed that the DNA segment between −228 and −150 bp containing the cAMP response element (CRE) site played a critical role. Thrombin also induced phosphorylation of CRE binding protein (CREB) in an ERK- and a p38 MAPK-dependent manner. Overexpression of the dominant-negative form of CREB inhibited thrombin-induced IL-6 mRNA expression. These results suggest that the CRE site and CREB play an important role in thrombin-induced IL-6 gene expression in VSMCs. Transactivation of EGF-R and activation of ERK and p38 MAPK are involved in this process. CREB may be a novel transcription factor that regulates thrombin-induced gene expression.
Acute and Chronic Smooth Muscle Cell Apoptosis After Mechanical Vascular Injury Can Occur Independently of the Fas-Death Pathway
Authors: Sata Masataka , Sugiura Seiryo , Yoshizumi Masao , Ouchi Yasuyoshi , Hirata Yasunobu , Nagai Ryozo
Published: September 2007

Vascular smooth muscle cell (VSMC) apoptosis has been demonstrated in vascular lesions, such as atherosclerotic and postangioplasty restenotic lesions. Balloon injury also induces VSMC apoptosis. Fas is a death factor that mediates apoptosis when it is activated by its ligand, FasL. Fas-mediated apoptosis was found to be implicated in the pathogenesis of vascular diseases in which Fas/FasL expression was detected. We investigated whether the Fas/FasL interaction mediated acute and chronic VSMC apoptosis and lesion formation in a vascular injury model that may resemble balloon angioplasty. A large spring wire was inserted into the femoral artery of C3H/HeJ (wild-type), C3H-
gld
(Fas ligand−/−), and C3H-
lpr
(Fas−/−) mice. The wire was left in place for 1 minute to denude and expand the artery. Massive apoptosis was observed in medial VSMCs from 1 to 7 hours later. There was no difference in the number of apoptotic cells among the 3 groups of mice 4 hours after injury. At 4 weeks, the injured arteries presented signs of concentric neointimal hyperplasia composed exclusively of VSMCs. There was no difference in the degree of neointima hyperplasia (intima/media ratios were as follows: wild type 1.4±0.3,
gld
1.0±0.2, and
lpr
1.3±0.2) or in the number of apoptotic nuclei among the 3 groups. These findings suggest the existence of other signaling pathways for acute and chronic VSMC apoptosis, at least that induced by mechanical vascular injury.
Myeloperoxidase and Hypochlorite, but Not Copper Ions, Oxidize Heparin-Bound LDL Particles and Release Them From Heparin
Authors: Pentikäinen Markku O. , Öörni Katariina , Kovanen Petri T.
Published: September 2007

Abstract
—

A key factor in atherosclerosis is the retention of low density lipoprotein (LDL) in the extracellular matrix of the arterial intima, where it binds to the negatively charged glycosaminoglycan chains of proteoglycans. Oxidation may lead to modification of the lysine residues of apolipoprotein B-100 of LDL, which normally mediate the binding of LDL to glycosaminoglycans. Here, we studied whether various modes of oxidation can release LDL from heparin, a glycosaminoglycan with a strong negative charge, in vitro. We found that copper ions were unable to oxidize heparin-bound LDL particles because of their redox inactivation by the glycosaminoglycans. In contrast, myeloperoxidase and hypochlorite, a product of myeloperoxidase, were able to oxidize heparin-bound LDL, and this oxidation led to the release of the oxidized particles from heparin. When the released LDL particles were compared with the residual heparin-bound LDL particles, the released particles were more electronegative and contained more modified lysine residues than did the particles that remained bound. Because human atherosclerotic lesions contain catalytically active myeloperoxidase and (lipo)proteins modified by hypochlorite, the results suggest that myeloperoxidase-secreting monocytes/macrophages in the arterial intima can oxidize and extract LDL from the extracellular matrix with ensuing uptake by the macrophages of the oxidized and released LDL, with eventual formation of foam cells.
Pretreatment With Simvastatin Attenuates Myocardial Dysfunction After Ischemia and Chronic Reperfusion
Authors: Jones Steven P. , Trocha Steven D. , Lefer David J.
Published: September 2007

We have previously demonstrated that simvastatin attenuates myocardial cell necrosis after acute myocardial ischemia and reperfusion via induction of endothelial cell NO synthase. However, it remains unknown whether the cardioprotective effects of statins can persist after extended periods of reperfusion. Furthermore, it is unknown whether simvastatin therapy can attenuate postischemic cardiac dysfunction. Pretreatment with simvastatin attenuated myocardial injury after 30 minutes of myocardial ischemia and 24 hours of reperfusion. However, the protective effects are not recognized unless simvastatin is given at least 3 hours before myocardial ischemia. Subsequently, we pretreated mice with vehicle or simvastatin and subjected the mice to 30 minutes of myocardial ischemia and 6 months of reperfusion. Myocardial infarct size (percentage of left ventricle) was significantly reduced by 51% in the simvastatin-treated group compared with the vehicle-treated group. Left ventricular diastolic and systolic dilatation was significantly (
P
<0.05) reduced in simvastatin-treated mice compared with vehicle-treated mice. Additionally, the decrement in fractional shortening after 6 months of reperfusion was minimized in simvastatin-treated mice (
P
=NS versus baseline) compared with vehicle-treated mice (
P
<0.05 versus baseline). Left ventricular end-diastolic pressure was significantly (
P
<0.01) elevated in vehicle-treated mice (21±4 mm Hg) but not simvastatin-treated mice (5±2 mm Hg) compared with baseline values. These data demonstrate that simvastatin treatment before myocardial ischemia attenuates infarct size and preserves myocardial function after chronic reperfusion in mice.
Plasminogen Activator Inhibitor-1 and Relations to Fatty Acid Composition in the Diet and in Serum Cholesterol Esters
Authors: Byberg Liisa , Smedman Annika , Vessby Bengt , Lithell Hans
Published: September 2007

High plasminogen activator inhibitor (PAI)-1 levels and poor dietary fat quality are potential risk factors for cardiovascular disease. The aim was to investigate the cross-sectional associations between PAI-1 activity and dietary nutrient intake, focusing on fat quality, in a population-based study of 871 men aged 70 years. The relationship between PAI-1 and the fatty acid composition in serum cholesterol esters (n=381 men) was also studied. The estimated total fat intake was positively associated with PAI-1 activity. The intake of both monounsaturated and polyunsaturated fatty acids was positively associated with PAI-1 activity, whereas the intake of saturated fatty acids was not. In serum cholesterol esters, higher proportions of palmitoleic and dihomo-γ-linolenic acid, a lower proportion of linoleic acid, and reduced estimated Δ5-desaturase activity were associated with higher PAI-1 levels. These associations were confounded by factors representing the insulin resistance syndrome. PAI-1 activity was positively associated with γ-linolenic and arachidonic acid, independent of potential confounders. In conclusion, this study demonstrates that dietary intake of unsaturated fatty acids is positively associated with PAI-1 activity, whereas intake of saturated fatty acids is not. The associations present between PAI-1 activity and the fatty acid proportions in serum cholesterol esters are partly influenced by metabolic syndrome-related factors.
Differential Expression of Bone Matrix Regulatory Proteins in Human Atherosclerotic Plaques
Authors: Dhore Cherida R. , Cleutjens Jack P.M. , Lutgens Esther , Cleutjens Kitty B.J.M. , Geusens Piet P.M. , Kitslaar Peter J.E.H.M. , Tordoir Jan H.M. , Spronk Henri M.H. , Vermeer Cees , Daemen Mat J.A.P.
Published: September 2007

In the present study, we examined the expression of regulators of bone formation and osteoclastogenesis in human atherosclerosis because accumulating evidence suggests that atherosclerotic calcification shares features with bone calcification. The most striking finding of this study was the constitutive immunoreactivity of matrix Gla protein, osteocalcin, and bone sialoprotein in nondiseased aortas and the absence of bone morphogenetic protein (BMP)-2, BMP-4, osteopontin, and osteonectin in nondiseased aortas and early atherosclerotic lesions. When atherosclerotic plaques demonstrated calcification or bone formation, BMP-2, BMP-4, osteopontin, and osteonectin were upregulated. Interestingly, this upregulation was associated with a sustained immunoreactivity of matrix Gla protein, osteocalcin, and bone sialoprotein. The 2 modulators of osteoclastogenesis (osteoprotegerin [OPG] and its ligand, OPGL) were present in the nondiseased vessel wall and in early atherosclerotic lesions. In advanced calcified lesions, OPG was present in bone structures, whereas OPGL was only present in the extracellular matrix surrounding calcium deposits. The observed expression patterns suggest a tight regulation of the expression of bone matrix regulatory proteins during human atherogenesis. The expression pattern of both OPG and OPGL during atherogenesis might suggest a regulatory role of these proteins not only in osteoclastogenesis but also in atherosclerotic calcification.
Sterol Efflux Mediated by Endogenous Macrophage ApoE Expression Is Independent of ABCA1
Authors: Huang Zhi Hua , Lin Chen-Yi , Oram John F. , Mazzone Theodore
Published: September 2007

Sterol efflux importantly contributes to preservation of cellular cholesterol homeostasis, and multiple pathways may be involved for mediating such efflux. Recently, an important role has been ascribed to ABCA1 in facilitating lipid efflux from cells, including macrophages, to extracellular lipid-free apolipoproteins. Macrophages are relatively unique among cells because they express apoprotein E (apoE) as a major protein product, and this endogenous expression of apoE increases sterol and phospholipid efflux from macrophages. The studies in this article were designed to test whether the sterol efflux mediated by the endogenous expression of apoE in macrophages was dependent on ABCA1 expression. These studies were facilitated by comparing apoE-expressing J774 cells (J774E
+
) with nonexpressing parental cells (J774E
−
). Sterol efflux was higher from J774E
+
cells compared with J774E
−
cells, but the increment in efflux between these cell types was not increased by induction of ABCA1 expression with cAMP. Induction of ABCA1 with cAMP, however, did increase sterol efflux to exogenously added apoA1 from both cell types. Inhibitors of ABCA1 activity significantly reduced (by 40% to 50%) sterol efflux from both J774E
+
and J774E
−
cells treated with cAMP and apoA1. This inhibitor did not, however, reduce the increment in sterol efflux due to the expression of endogenous apoE. The results of these studies indicate that the increment in sterol efflux mediated by the endogenous expression of apoE in macrophages does not depend on ABCA1 expression or activity.
Neutrophil Enhancement of Fibrin Deposition Under Flow Through Platelet-Dependent and -Independent Mechanisms
Authors: Goel Mukul S. , Diamond Scott L.
Published: September 2007

We examined the effect of adherent neutrophils on fibrin deposition under laminar flow conditions. Perfusion of recalcified citrated platelet-free plasma (PFP) over neutrophils adherent to fibrinogen-coated glass at a venous wall shear rate of 62.5 s
−1
for 15 minutes resulted in dense deposition of fibrin around each neutrophil, whereas fibrin deposition on glass alone was sparse. Fibrin deposition on neutrophils was markedly reduced by anti-CD18 or anti-CD11b or a higher shear rate (250 s
−1
). Significantly less fibrin was deposited around adherent fibrinogen-coated beads, indicating that nonspecific “cross-sectional capture” effects were not responsible for the massive fibrin deposition on neutrophils. Direct visualization of fibrin capture by neutrophils and elimination of fibrin deposition at 15 minutes by a factor XIIa inhibitor (50 μg/mL corn trypsin inhibitor [CTI]) or elastase/cathepsin G inhibitors (Methoxysuccinyl-Ala-Ala-Pro-Ala-Chloromethyl-Ketone/Z-Gly-Leu-Phe-CMK, 100 μmol/L) indicated that neutrophils can capture short fibrin strands flowing in recalcified PFP lacking CTI and can also promote thrombin generation through pathways attenuated by inhibitors of factor XIIa, elastase, and cathepsin G. When neutrophils were allowed to interact with platelets on a fibrinogen surface before perfusion of recalcified CTI-treated PFP, the fibrin deposition was observed to be dramatic compared with that over surfaces coated with platelets alone or neutrophils alone and compared with that formed on platelets adherent to collagen. This neutrophil promotion of platelet-mediated fibrin formation was attenuated by inhibitors of elastase or cathepsin G but not anti-tissue factor antibody. Neutrophils can interact with platelets via released proteases to increase platelet procoagulant activity and fibrin formation in CTI-treated plasma under the low-flow conditions expected in venous thrombosis or inflammation.
Ezetimibe, a Potent Cholesterol Absorption Inhibitor, Inhibits the Development of Atherosclerosis in ApoE Knockout Mice
Authors: Davis Harry R. , Compton Douglas S. , Hoos Lizbeth , Tetzloff Glen
Published: September 2007

Ezetimibe (SCH58235) is a potent, selective, cholesterol absorption inhibitor. The objective of this study was to determine whether ezetimibe reduces plasma cholesterol and inhibits atherogenesis in apolipoprotein E knockout (apoE−/−) mice. Cholesterol absorption was inhibited by >90% at doses of ezetimibe >3 mg/kg in apoE−/− mice. Atherosclerosis and lipoprotein changes were determined in apoE−/− mice fed a high-fat (0.15% cholesterol) “western” diet, a low-fat (0.15% cholesterol) diet, or a semisynthetic cholesterol-free diet with or without ezetimibe (5 mg/kg per day) for 6 months. Ezetimibe reduced plasma cholesterol levels from 964 to 374 mg/dL, from 726 to 231 mg/dL, and from 516 to 178 mg/dL in the western, low-fat, and cholesterol-free diet groups, respectively. The reductions occurred in the very low density and low density lipoprotein fractions, whereas high density lipoprotein cholesterol levels were increased by ezetimibe treatment. Ezetimibe reduced aortic atherosclerotic lesion surface area from 20.2% to 4.1% in the western diet group and from 24.1% to 7.0% in the low-fat cholesterol diet group. Ezetimibe reduced carotid artery atherosclerotic lesion cross-sectional area by 97% in the western and low-fat cholesterol groups and by 91% in the cholesterol-free group. Ezetimibe inhibits cholesterol absorption, reduces plasma cholesterol, increases high density lipoprotein levels, and inhibits the progression of atherosclerosis under western, low-fat, and cholesterol-free dietary conditions in apoE−/− mice. Although apoE−/− mice are more hypercholesterolemic than are humans and low density lipoprotein reductions with ezetimibe are not as pronounced clinically, ezetimibe may inhibit atherogenesis in individuals consuming restricted-fat or western diets.
Analysis of the Ileal Bile Acid Transporter Gene,
SLC10A2
, in Subjects With Familial Hypertriglyceridemia
Authors: Love Martha W. , Craddock Ann L. , Angelin Bo , Brunzell John D. , Duane William C. , Dawson Paul A.
Published: September 2007

Familial hypertriglyceridemia (FHTG), a disease characterized by elevated plasma very low density lipoprotein triglyceride levels, has been associated with impaired intestinal absorption of bile acids. The aim of this study was to test the hypothesis that defects in the active ileal absorption of bile acids are a primary cause of FHTG. Single-stranded conformation polymorphism analysis was used to screen the ileal Na
+
/bile acid cotransporter gene (
SLC10A2
) for FHTG-associated mutations. Analysis of 20 hypertriglyceridemic patients with abnormal bile acid metabolism revealed 3 missense mutations (V98I, V159I, and A171S), a frame-shift mutation (646insG) at codon 216, and 4 polymorphisms in the 5′ flanking sequence of
SLC10A2
. The
SLC10A2
missense mutations and 5′ flanking sequence polymorphisms were not correlated with bile acid production or turnover in the hypertriglyceridemic patients and were equally prevalent in the unaffected control subjects. In transfected COS cells, the V98I, V159I, and A171S isoforms all transported bile acids similar to the wild-type
SLC10A2
. The 646insG frame-shift mutation abolished bile acid transport activity in transfected COS cells but was found in only a single FHTG patient. These findings indicate that the decreased intestinal bile acid absorption in FHTG patients is not commonly associated with inherited defects in
SLC10A2
.
Gene Therapy for Hypertension
Authors: Phillips M. Ian
Published: September 2007

Abstract
—

— Despite several drugs for the treatment of hypertension, there are many patients with poorly controlled high blood pressure. This is partly because all of the available drugs are short-lasting (≤24 hours), have side effects, and are not highly specific. Gene therapy offers a possibility of producing longer-lasting effects with precise specificity based on the genetic design. Preclinical studies on gene therapy for hypertension have taken 2 approaches. Chao et al have performed extensive studies on gene transfer to increase vasodilator proteins. They have transferred kallikrein, atrial natriuretic peptide, adrenomedullin, and endothelin NO synthase into different rat models. Their results show that blood pressure can be lowered for 3 to 12 weeks with the expression of these genes. The antisense approach, which we began by targeting angiotensinogen and the angiotensin type 1 (AT
1
) receptor, has now been tested independently by several different groups in multiple models of hypertension. Other genes targeted include the β
1
-adrenoceptor, thyrotropin-releasing hormone, angiotensin gene-activating elements, carboxypeptidase Y, c-
fos
, and CYP4A1. There have been 2 methods of delivering antisense: one is by oligodeoxynucleotides, and the other is with full-length DNA in viral vectors. All the studies show a decrease in blood pressure lasting several days to weeks or months. Oligos are safe and nontoxic and could be delivered orally or eventually by skin patches. Systemic delivery of recombinant adeno-associated virus with DNA antisense to AT
1
receptors in adult rodents decreases hypertension for up to 6 months. We conclude that there is sufficient preclinical data to give serious consideration to phase I trials for testing some of the antisense oligodeoxynucleotides, although testing the viral vectors needs much more work.
Angiotensin II and Renal Fibrosis
Authors: Mezzano Sergio A. , Ruiz-Ortega Marta , Egido Jesús
Published: September 2007

Abstract
—

— Angiotensin (Ang) II, the main peptide of the renin angiotensin system (RAS), is a renal growth factor, inducing hyperplasia/hypertrophy depending on the cell type. This vasoactive peptide activates mesangial and tubular cells and interstitial fibroblasts, increasing the expression and synthesis of extracellular matrix proteins. Some of these effects seem to be mediated by the release of other growth factors, such as TGF-β. In experimental models of kidney damage, renal RAS activation, cell proliferation, and upregulation of growth factors and matrix production were described. In some of these models, blockade of Ang II actions by ACE inhibitors and angiotensin type 1 (AT
1
) antagonists prevents proteinuria, gene expression upregulation, and fibrosis, as well as inflammatory cell infiltration. Interestingly, Ang II could also be involved in the fibrotic process because of its behavior as a proinflammatory cytokine, participating in various steps of the inflammatory response: Ang II (1) activates mononuclear cells and (2) increases proinflammatory mediators (cytokines, chemokines, adhesion molecules, nuclear factor κB). Finally, Ang II also regulates matrix degradation. These data show that drugs controlling this complex vasoactive peptide are probably one of the best ways of avoiding fibrosis in progressive renal diseases.
Chronic AT
1
Receptor Blockade Alters Autonomic Balance and Sympathetic Responses in Hypertension
Authors: Bezerra Simone M.M.S. , dos Santos Claudia M. , Moreira Edson D. , Krieger Eduardo M. , Michelini Lisete C.
Published: September 2007

Abstract
—

— In the coarctation hypertension model, we have shown that chronic treatment with losartan causes both normalization of impaired reflex control of heart rate and partial correction of the depressed aortic nerve activity/pressure relationship, even with the persistence of hypertension. In the present study, we analyzed the effects of angiotensin II blockade on the efferent pathways of coarcted and sham-operated groups treated chronically with vehicle or losartan (10 mg/kg per day PO). Hypertension was induced by subdiaphragmatic aortic coarctation, and the treatments lasted 9 days (4 control and 5 experimental days). On day 5, autoregressive power spectral analysis was performed on heart rate recordings made in conscious rats. Other groups were used for sympathetic splanchnic nerve activity recordings made simultaneously with pressure (anesthetized rats) at basal condition and during loading/unloading of baroreceptors. Losartan treatment induced a significant reduction in basal pressure but did not interfere with the development of hypertension (similar pressure increases of 24% and 28% over control values in losartan and vehicle groups, respectively). In vehicle-treated rats, establishment of hypertension was accompanied by a marked change in power spectral density from high- (1.19±0.06 Hz, 33±6%) to low-frequency components (0,42±0.03 Hz, 54±6%), with increased low-frequency–to–high-frequency ratio. When compared with sham-operated vehicle-treated rats, there was also increase in the gain of sympathetic activity/pressure relationship, with displacement of lower plateau toward high levels of sympathetic activity. No changes in the power spectral density and sympathetic activity/pressure relationship were observed when hypertension developed in the presence of chronic angiotensin type 1 (AT
1
) receptor blockade. The data suggest that angiotensin II, activated during the establishment of coarctation hypertension, acts via AT
1
receptors to alter sympathovagal balance, facilitating the sympathetic outflow to heart and peripheral circulation during baroreceptors unloading. Data also indicate that the observed effects are not conditioned by preexisting pressure levels.
ACE Inhibitors and Appearance of Renal Events in Hypertensive Nephrosclerosis
Authors: Segura Julián , Campo Carlos , Rodicio José L. , Ruilope Luis M.
Published: September 2007

Abstract
—

— Nephrosclerosis constitutes a major cause of end-stage renal disease. Independently of blood pressure control, ACE inhibitors (ACEIs) are considered to be more nephroprotective than other antihypertensive agents. We have reviewed the long-term evolution of renal function in our series of essential hypertensive patients diagnosed as having nephrosclerosis when first seen in our unit. The analysis was performed depending on whether or not their antihypertensive therapy contained an ACEI alone or in combination for the whole follow-up. The end point was defined as the confirmation of a 50% reduction in creatinine clearance or entry in a dialysis program. A historical cohort of 295 patients was included in the analysis. Mean follow-up was 7.4±3.9 years. Diabetes prevalence was higher in ACEI-treated patients (25.7% versus 7.1%,
P
=0.000), but the diagnosis of diabetic nephropathy could not be confirmed on clinical grounds, including renal biopsy. Twenty-three out of 183 (12.6%) patients in the ACEI group and 23 out of 112 (20.5%) patients in the non-ACEI group experienced a renal event (
P
=0.0104 by log rank test). Similar results were observed when only nondiabetic patients were considered for the analysis. Cox regression analysis showed that baseline serum creatinine, absence of ACEI administration, mean proteinuria during follow-up, and age were independent predictors for the development of a renal event. In hypertensive nephrosclerosis, therapy containing an ACEI alone or in combination significantly reduces the incidence of renal events. This effect is independent of blood pressure control.