bluuebunny/crossref_metadata_2025 huggingface dataset:
Retention of Oxidized LDL by Extracellular Matrix Proteoglycans Leads to Its Uptake by Macrophages
Authors: Kaplan Marielle , Aviram Michael
Published: June 2011

Abstract
—Interaction between arterial macrophages and oxidized LDL (Ox-LDL) leads to foam cell formation, a critical step during early atherogenesis. Until now, cellular uptake of lipoproteins was studied through incubation of the media-soluble lipoprotein with cultured macrophages. However, as lipoproteins in the arterial wall are bound to subendothelial matrix, we questioned whether the retention (binding) of Ox-LDL to a macrophage-derived extracellular matrix (ECM) could lead to enhanced uptake by macrophages. The uptake of ECM-bound Ox-LDL by activated macrophages (by phorbol myristate acetate) was lipoprotein dose dependent, time dependent and higher (by 1.5-fold) than the uptake of ECM-bound native LDL. Preincubation of the ECM with lipoprotein lipase before the addition of Ox-LDL was essential for the uptake of ECM-bound Ox-LDL by the macrophages. After radiolabeling of the ECM glycosaminoglycans (GAGs), we found that ECM-bound Ox-LDL is taken up by the macrophages together with the ECM-GAG. Finally, these results were further confirmed through the use of ECM obtained from mouse peritoneal macrophages (MPMs), derived from atherosclerotic, apoE-deficient mice. In 24-week-old mice with developed atherosclerosis, the GAG content of their MPM-derived ECM increased by 52%, the ability of their MPM-derived ECM to bind Ox-LDL increased by 57%, and macrophage uptake of Ox-LDL that was retained by the MPM-derived ECM increased by 86%. In conclusion, the present study demonstrated that ECM-bound Ox-LDL is taken up by activated macrophages. This may represent a physiopathological phenomenon that leads to cholesterol and oxysterol accumulation in arterial macrophages, the hallmark of early atherosclerosis.
Long-Chain n-3 Fatty Acids Specifically Affect Rat Coagulation Factors Dependent on Vitamin K
Authors: Leray Claude , Wiesel Marie-Louise , Freund Monique , Cazenave Jean-Pierre , Gachet Christian
Published: June 2011

Abstract
—Fatty acids of marine origin have been shown to affect blood coagulation in the rat. In an attempt to gain insight into the mechanisms of this phenomenon, we studied the effects of dietary linseed and fish oils on the liver antioxidant status and plasma coagulation parameters in rats on a time-course basis. Dietary enrichment in eicosapentaenoic and docosahexaenoic acids resulted in strong hypocoagulation after only 1 week and a concomitant increase in liver lipid peroxidation and tocopherolquinone content. Enrichment in linolenic acid induced similar increases in lipid peroxidation and tocopherol catabolism but negligible alteration of coagulation. A significant correlation between plasma factor II coagulant activity and liver tocopherolquinone was found in fish oil– but not in linseed oil–fed rats. Although ingestion of tocopherolquinone led to high levels of this compound in the liver, it had only marginal effects on coagulation factors. Thus, it seems unlikely that this vitamin E metabolite could be involved in the lowering of vitamin K–dependent clotting factors through inhibition of γ-glutamylcarboxylase. Rather, our results indicate that the effects of the n-3 fatty acids of fish oil on vitamin K–dependent coagulation factors are specific and independent of liver tocopherolquinone levels.
Epidermal Growth Factor Receptor Transactivation by Angiotensin II Requires Reactive Oxygen Species in Vascular Smooth Muscle Cells
Authors: Ushio-Fukai Masuko , Griendling Kathy K. , Becker Peter L. , Hilenski Lula , Halleran Sean , Alexander R. Wayne
Published: June 2011

Abstract
—Angiotensin II (Ang II) is a vasoactive hormone with critical roles in vascular smooth muscle cell growth, an important feature of hypertension and atherosclerosis. Many of these effects are dependent on the production of reactive oxygen species (ROS). Ang II induces phosphorylation of the epidermal growth factor (EGF) receptor (EGF-R), which serves as a scaffold for various signaling molecules. Here, we provide novel evidence that ROS are critical mediators of EGF-R transactivation by Ang II. Pretreatment of vascular smooth muscle cells with the antioxidants diphenylene iodonium, Tiron,
N
-acetylcysteine, and ebselen significantly inhibited (≈80% to 90%) tyrosine phosphorylation of the EGF-R by Ang II but not by EGF. Of the 5 autophosphorylation sites on the EGF-R, Ang II mainly phosphorylated Tyr1068 and Tyr1173 in a redox-sensitive manner. The Src family kinase inhibitor PP1, overexpression of kinase-inactive c-Src, or chelation of intracellular Ca
2+
attenuated EGF-R transactivation. Although antioxidants had no effects on the Ca
2+
mobilization or phosphorylation of Ca
2+
-dependent tyrosine kinase Pyk2, they inhibited c-Src activation by Ang II, suggesting that c-Src is 1 signaling molecule that links ROS and EGF-R phosphorylation. Furthermore, Ang II–induced tyrosine phosphorylation of the autophosphorylation site and the SH2 domain of c-Src was redox sensitive. These findings emphasize the importance of ROS in specific Ang II–stimulated growth-related signaling pathways and suggest that redox-sensitive EGF-R transactivation may be a potential target for antioxidant therapy in vascular disease.
C-Reactive Protein, Fibrin D-Dimer, and Incident Ischemic Heart Disease in the Speedwell Study
Authors: Lowe Gordon D. O. , Yarnell John W. G. , Rumley Ann , Bainton David , Sweetnam Peter M.
Published: June 2011

Abstract
—Plasma levels of C-reactive protein (CRP, a marker of the reactant plasma protein component of the inflammatory response) and of fibrin D-dimer (a marker of cross-linked fibrin turnover) have each been associated in recent studies with the risk of future ischemic heart disease (IHD). Previous experimental studies have shown that fibrin degradation products, including D-dimer, have effects on inflammatory processes and acute-phase protein responses. In the Speedwell Prospective Study, we therefore measured CRP and D-dimer levels in stored plasma samples from 1690 men aged 49 to 67 years who were followed-up for incident IHD for an average of 75±4 months (mean±SD) and studied their associations with each other, with baseline and incident IHD, and with IHD risk factors. CRP and D-dimer levels were each associated with age, plasma fibrinogen, smoking habit, and baseline evidence of IHD. CRP was associated with D-dimer (
r
=0.21,
P
<0.00001). On univariate analyses, both CRP and D-dimer were associated with incident IHD. The incidence of IHD increased with CRP independently of the level of D-dimer (
P
=0.0002) and also increased with D-dimer independently of the level of CRP (
P
=0.048). In multivariate analyses, inclusion of D-dimer and conventional risk factors reduced the strength of the association between CRP and incident IHD; likewise, inclusion of CRP and conventional risk factors reduced the strength of the association between D-dimer and incident IHD. We conclude that although these respective markers of inflammation and fibrin turnover show modest association with each other in middle-aged men, they may have additive associations with risk of incident IHD. Further larger studies are required to test this hypothesis.
Prospective Study of Fibrinolytic Factors and Incident Coronary Heart Disease
Authors: Folsom Aaron R. , Aleksic Nena , Park Eunsik , Salomaa Veikko , Juneja Harinder , Wu Kenneth K.
Published: June 2011

Abstract
—The fibrinolytic system may play a role in the pathogenesis of coronary heart disease (CHD), but existing prospective studies have not consistently shown an independent association between fibrinolytic factors and CHD. None has reported an association between plasminogen and CHD incidence. In the prospective Atherosclerosis Risk in Communities (ARIC) Study of middle-aged adults, we examined the association of incident CHD with several fibrinolytic factors: tissue plasminogen activator antigen, plasminogen activator inhibitor-1, plasminogen, and fibrin fragment D-dimer as well as a marker of coagulation activation (prothrombin fragment F1.2). We measured these in stored baseline plasma samples of 326 subjects who developed CHD and, for comparison, a stratified random sample of the entire cohort (n=720). Tissue plasminogen activator and plasminogen activator inhibitor-1 antigen levels were associated positively with CHD incidence in analyses adjusted for age, race, and sex but were not associated with CHD after adjustment for other risk factors. Plasminogen and D-dimer levels were associated positively and independently with CHD incidence; the multivariable-adjusted relative risks (95% CIs) for the highest versus lowest quintiles were 2.20 (1.2 to 4.2) for plasminogen and 4.21 (1.9 to 9.6) for D-dimer. F1.2 was not associated with CHD incidence. Our findings lend support for a link between fibrinolytic factors and CHD incidence. A positive association between plasminogen and CHD is seemingly opposite the direction expected but may reflect a compensatory response to impaired plasminogen activation in subjects prone to CHD.
Vascular Injury Induces Posttranscriptional Regulation of the Id3 Gene
Authors: Matsumura Martin E. , Li Feng , Berthoux Lionel , Wei Beiyang , Lobe David R. , Jeon Cathy , McNamara Coleen A.
Published: June 2011

Abstract
—The molecular mechanisms that regulate the proliferation of smooth muscle cells (SMCs) of the vasculature in response to injury are poorly understood. Members of the inhibitor of DNA binding (Id) class of helix-loop-helix transcription factors are known to regulate the growth of a variety of cell types; however, the expression of the various Id genes in SMCs and in vascular lesions has not been examined. In the present study, the yeast 2-hybrid system was used to clone Id genes from a cultured rat aortic SMC library. By use of ubiquitous E proteins as bait, Id3 and a novel isoform of Id3 (Id3a) were cloned. Id3a is the product of alternative splicing of the Id3 gene, resulting in inclusion of a 115-bp “coding intron,” which encodes a unique 29–amino acid carboxyl terminus for the Id3a protein. Unlike Id3, Id3a mRNA was not detected in the normal rat carotid artery. However, after balloon injury, Id3a was abundantly expressed throughout the neointimal layer. In addition, mRNA of the human homologue of Id3a (Id3L) was detected in human carotid atherosclerotic plaques. Adenovirus-mediated overexpression of these Id3 isoforms in cultured rat aortic SMCs revealed that infection of SMCs with an adenovirus overexpressing Id3a (in contrast to Id3) resulted in a significant decrease in cell number versus AdLacZ-infected cells. DNA fragmentation analysis suggested that this decrease in SMC viability was due to increased apoptotic activity in cells infected with adenovirus overexpressing Id3a. These results provide evidence that alternative splicing of the Id3 gene may represent an important mechanism by which neointimal SMC growth is attenuated during vascular lesion formation.
Cross-Linking of Brain Endothelial Intercellular Adhesion Molecule (ICAM)-1 Induces Association of ICAM-1 With Detergent-Insoluble Cytoskeletal Fraction
Authors: Amos Claire , Romero Ignacio A. , Schültze Charlotte , Rousell Jonathan , Pearson Jeremy D. , Greenwood John , Adamson Peter
Published: June 2011

Abstract
—Intercellular adhesion molecule (ICAM)-1 plays a vital role in the process of leukocyte transmigration through endothelial cell (EC) barriers and has been shown to mediate signal transduction events in ECs induced either by its cross-linking or by the binding of T lymphocytes. Immunoblotting of ICAM-1 of Triton X-100 detergent fractions demonstrated that the majority of ICAM-1 was contained within the detergent-soluble fraction (noncytoskeletal associated) under basal conditions. After cross-linking of endothelial ICAM-1 with monoclonal antibody or coculture with T lymphocytes, EC ICAM-1 was observed to partition with a Triton X-100–insoluble (cytoskeletal associated) fraction in a dose- and time-dependent manner. Redistribution of ICAM-1 was specific, inasmuch as no association with the Triton X-100–insoluble fraction was observed after cross-linking of vascular cell adhesion molecule-1, nor did cross-linking of ICAM-1 result in a redistribution of the platelet and EC adhesion molecule. ICAM-1 association with the endothelial cytoskeleton after cross-linking was unaffected after treatment of the cells with cytochalasin D, C3-transferase, removal of extracellular calcium ions, or chelation of intracellular calcium ions. These data show that ICAM-1 colocalizes with the endothelial cytoskeleton and associates with a detergent-insoluble fraction after cross-linking.
Oral Magnesium Supplementation Induces Favorable Antiatherogenic Changes in ApoE-Deficient Mice
Authors: Ravn Hanne B. , Korsholm Trine L. , Falk Erling
Published: June 2011

Abstract
—Epidemiological studies indicate that dietary magnesium influences atherogenesis. Magnesium inhibits plaque formation in animals receiving a high cholesterol diet, whereas the effect of magnesium in animals on low-fat diet has not been explored. Magnesium sulfate was given in the drinking water (50 mg/mL) to 7-week-old apolipoprotein E–deficient (apoE
−
/
−
) mice (n=30). Control animals (n=30) received tap water. At the age of 19 weeks, the extent of atherosclerosis and the density of macrophages were measured in the aortic root, and blood lipids were analyzed. The median plaque area was significantly smaller in magnesium-treated female apoE
−
/
−
mice and reached only 66% of control females (
P
<0.02). Plaque area was also less extensive in magnesium-treated male mice, although not statistically significant. Macrophage density was similar in both groups. Magnesium significantly reduced cholesterol (
P
<0.05) and triglyceride (
P
<0.01) levels, whereas high density lipoprotein cholesterol remained stable. No significant differences in body and heart weight were seen between treatment groups for either sex. In conclusion, in apoE
−
/
−
mice receiving a low-fat diet, magnesium supplementation significantly inhibited atherogenesis in females but not males. Plaque composition remained unchanged in terms of macrophage density. This was obtained in association with significantly reduced levels of cholesterol and triglycerides.
Dietary Plant Stanol Esters Reduce VLDL Cholesterol Secretion and Bile Saturation in Apolipoprotein E*3-Leiden Transgenic Mice
Authors: Volger Oscar L. , van der Boom Hans , de Wit Elly C. M. , van Duyvenvoorde Wim , Hornstra Gerard , Plat Jogchum , Havekes Louis M. , Mensink Ronald P. , Princen Hans M. G.
Published: June 2011

Abstract
—Dietary plant stanols lower serum cholesterol levels in humans and in hyperlipidemic rodents, mainly by inhibition of the intestinal cholesterol absorption. We used female apolipoprotein E*3-Leiden transgenic mice to investigate the consequences of this effect on serum lipid levels and hepatic lipid metabolism. Five groups of 6 or 7 mice received for 9 weeks a diet containing 0.25% cholesterol and 0.0%, 0.25%, 0.5%, 0.75%, or 1.0% (wt/wt) plant stanols (sitostanol 88% [wt/wt], campestanol 10% [wt/wt]) esterified to fatty acids. Compared with the control diet, plant stanol ester treatment dose-dependently reduced serum cholesterol levels by 10% to 33% (
P
<0.05), mainly in very low density lipoproteins (VLDLs), intermediate density lipoproteins, and low density lipoproteins. Furthermore, 1.0% of the dietary plant stanols significantly decreased the liver contents of cholesteryl esters (−62%), free cholesterol (−31%), and triglycerides (−38%) but did not change the hepatic VLDL-triglyceride and VLDL–apolipoprotein B production rates. However, plant stanol ester feeding significantly decreased the amounts of cholesteryl esters and free cholesterol incorporated in nascent VLDLs by 72% and 30%, respectively, resulting in a net 2-fold decreased VLDL cholesterol output. Liver mRNA levels of low density lipoprotein receptors, 3-hydroxy-3-methylglutaryl coenzyme A synthase, cholesterol 7α-hydroxylase, and sterol 27-hydroxylase were not changed by plant stanol ester feeding. Nevertheless, the serum lathosterol-to-cholesterol ratio was significantly increased by 23%, indicating that dietary plant stanol esters increased whole-body cholesterol synthesis. Plant stanol esters also significantly decreased the cholesterol saturation index in bile by 55%. In conclusion, in apolipoprotein E*3-Leiden transgenic mice, plant stanol ester feeding dose-dependently lowered serum cholesterol levels as a result of a reduced secretion of VLDL cholesterol. This was caused by a decreased hepatic cholesterol content that also resulted in a lowered biliary cholesterol output, indicative of a reduced lithogenicity of bile in these mice.
Effect of Acute and Chronic Tea Consumption on Platelet Aggregation in Patients With Coronary Artery Disease
Authors: Duffy Stephen J. , Vita Joseph A. , Holbrook Monika , Swerdloff Peter L. , Keaney John F.
Published: June 2011

Abstract
—Epidemiological studies suggest that tea consumption is associated with a decreased risk of cardiovascular events, but the mechanisms of benefit remain undefined. Platelet aggregation is a precipitating event in cardiovascular disease, and tea contains antioxidant flavonoids that are known to decrease platelet aggregation in vitro. To test the effect of tea consumption on platelet aggregation, we randomized 49 patients with coronary artery disease to either 450 mL of black tea or water consumed initially, followed by 900 mL of tea or water daily for 4 weeks in a crossover design. Ex vivo platelet aggregation in platelet-rich plasma was assessed in response to ADP and thrombin receptor–activating peptide at baseline and 2 hours and 4 weeks after beverage consumption. We observed dose-dependent platelet aggregation in response to each agonist, and neither relation was altered by acute or chronic tea consumption. Plasma flavonoids increased with acute and chronic tea consumption, indicating adequate absorption of tea flavonoids. In conclusion, these results demonstrate that acute and chronic black tea consumption does not affect ex vivo platelet aggregation in patients with coronary artery disease. These findings suggest that an effect of tea flavonoids on platelet aggregation is unlikely to be the explanation for the reduction in risk of cardiovascular events noted in epidemiological studies.
Receptor for Advanced Glycation End Products Mediates Inflammation and Enhanced Expression of Tissue Factor in Vasculature of Diabetic Apolipoprotein E–Null Mice
Authors: Kislinger Thomas , Tanji Nozomu , Wendt Thoralf , Qu Wu , Lu Yan , Ferran Luis J. , Taguchi Akihiko , Olson Kim , Bucciarelli Loredana , Goova Mouza , Hofmann Marion A. , Cataldegirmen Guellue , D’Agati Vivette , Pischetsrieder Monika , Stern David M. , Schmidt Ann Marie
Published: June 2011

Abstract
—Advanced glycation end products (AGEs) and their cell surface receptor, RAGE, have been implicated in the pathogenesis of diabetic complications. Here, we studied the role of RAGE and expression of its proinflammatory ligands, EN-RAGEs (S100/calgranulins), in inflammatory events mediating cellular activation in diabetic tissue. Apolipoprotein E–null mice were rendered diabetic with streptozotocin at 6 weeks of age. Compared with nondiabetic aortas and kidneys, diabetic aortas and kidneys displayed increased expression of RAGE, EN-RAGEs, and 2 key markers of vascular inflammation, vascular cell adhesion molecule (VCAM)-1 and tissue factor. Administration of soluble RAGE, the extracellular domain of the receptor, or vehicle to diabetic mice for 6 weeks suppressed levels of VCAM-1 and tissue factor in the aorta, in parallel with decreased expression of RAGE and EN-RAGEs. Diabetic kidney demonstrated increased numbers of EN-RAGE–expressing inflammatory cells infiltrating the glomerulus and enhanced mRNA for transforming growth factor-β, fibronectin, and α
1
(IV) collagen. In mice treated with soluble RAGE, the numbers of infiltrating inflammatory cells and mRNA levels for these glomerular cytokines and components of extracellular matrix were decreased. These data suggest that activation of RAGE primes cells targeted for perturbation in diabetic tissues by the induction of proinflammatory mediators.
C-Type Natriuretic Peptide Induces Redifferentiation of Vascular Smooth Muscle Cells With Accelerated Reendothelialization
Authors: Doi Kentaro , Ikeda Tadashi , Itoh Hiroshi , Ueyama Koji , Hosoda Kiminori , Ogawa Yoshihiro , Yamashita Jun , Chun Tae-Hwa , Inoue Mayumi , Masatsugu Ken , Sawada Naoki , Fukunaga Yasutomo , Saito Takatoshi , Sone Masakatsu , Yamahara Kenichi , Kook Hyun , Komeda Masashi , Ueda Makiko , Nakao Kazuwa
Published: June 2011

Abstract
—We recently reported that C-type natriuretic peptide (CNP) occurs in vascular endothelial cells and acts as a vascular-type natriuretic peptide. In the present study, we stimulated the cGMP cascade in proliferating smooth muscle cells (SMCs), in which particulate guanylate cyclase-B, the specific receptor for CNP, is predominantly expressed, by use of an adenovirus encoding rat CNP cDNA (Ad.CNP). In the Ad.CNP-treated cultured SMCs, CNP caused the growth inhibition of SMCs at G
1
phase with an early increase of p21
CIP1/WAF1
expression and subsequent upregulation of p16
INK4a
. The expression of smooth muscle myosin heavy chain-2, which is the molecular marker of highly differentiated SMCs, was reinduced in the Ad.CNP-treated SMCs. The Ad.CNP-treated SMCs also reexpressed particulate guanylate cyclase-A, which shows high affinity to atrial and brain natriuretic peptide and is exclusively expressed in well-differentiated SMCs. CNP, which was overexpressed in rabbit femoral arteries in vivo at the time of balloon injury, significantly suppressed neointimal formation. Furthermore, an enhancement of the expression of smooth muscle myosin heavy chain-2 occurred in the residual neointima. In addition, early regeneration of endothelial cells was observed in the Ad.CNP-infected group. Thus, stimulation of cGMP cascade in proliferating dedifferentiated SMCs can induce growth inhibition and redifferentiation of SMCs with accelerated reendothelialization.
Polylysine as a Vehicle for Extracellular Matrix–Targeted Local Drug Delivery, Providing High Accumulation and Long-Term Retention Within the Vascular Wall
Authors: Sakharov D. V. , Jie A. F. H. , Bekkers M. E. A. , Emeis J. J. , Rijken D. C.
Published: June 2011

Abstract
—We present the first steps in the elaboration of an approach of extracellular matrix–targeted local drug delivery (ECM-LDD), designed to provide a high concentration, ubiquitous distribution, and long-term retention of a drug within the vessel wall after local intravascular delivery. The approach is based on the concept of a bifunctional drug comprising a “therapeutic effector” and an “affinity vehicle,” which should bind to an abundant component of the vessel wall. The aim of the present study was to select molecules suitable for the role of affinity vehicles for ECM-LDD and to study their intravascular delivery and retention ex vivo and in an animal model. By use of fluorescence microscopy, the following molecules were selected on the basis of strong binding to cross sections of human vessels: protamine, polylysine, polyarginine, a glycosaminoglycan-binding peptide from vitronectin, and a synthetic dendrimer. With polylysine as a prototypic affinity vehicle, we showed that after intravascular delivery, polylysine was concentrated throughout a luminal layer of the vascular wall to an extremely high concentration of 20 g/L and was retained therein for at least 72 hours of perfusion without noticeable losses. Low molecular weight (fluorescein) and high molecular weight (hirudin) compounds could be chemically conjugated to polylysine and were retained in the vessel wall after intravascular delivery of the conjugates. In conclusion, by use of the ECM-LDD method, an extremely high concentration and long-term retention of locally delivered drug can be reached. Polycationic molecules can be considered as potential affinity vehicles for ECM-LDD.
Cultured Arterial Smooth Muscle Cells Maintain Distinct Phenotypes When Implanted Into Carotid Artery
Authors: Bochaton-Piallat Marie-Luce , Clowes Alexander W. , Clowes Monika M. , Fischer Jens W. , Redard Mireille , Gabbiani Françoise , Gabbiani Giulio
Published: June 2011

Abstract
—Cultured arterial smooth muscle cells (SMCs) with distinct phenotypic features have been described by several laboratories; however, it is not presently known whether this phenotypic heterogeneity can be maintained within an in vivo environment. To answer this question, we have seeded into the intima of denuded rat carotid artery 2 SMC populations with well-established distinct biological features, ie, spindle-shaped, not growing in the absence of serum, and well differentiated versus epithelioid, growing in the absence of serum, and relatively undifferentiated, derived from the aortic media of newborn rats (aged 4 days) and old rats (aged >18 months), respectively. We show that these 2 populations maintain their distinct biochemical features (ie, expression of α-smooth muscle actin, smooth muscle myosin heavy chains, and cellular retinol binding protein-1) in the in vivo environment. The old rat media–derived SMCs continue to produce cellular retinol binding protein-1 but little α-smooth muscle actin and smooth muscle myosin heavy chains, whereas the newborn rat media–derived SMCs continue to express α-smooth muscle actin and smooth muscle myosin heavy chains but no cellular retinol binding protein-1. Our results reinforce the notion of arterial SMC phenotypic heterogeneity and suggest that in our model, heterogeneity is controlled genetically and not by the local environment.
Endogenous Neutralizing Antibodies Against Platelet-Derived Growth Factor-AA Inhibit Atherogenesis in the Cholesterol-Fed Rabbit
Authors: Lamb David J. , Avades Tony Y. , Ferns Gordon A. A.
Published: June 2011

Abstract
—Previous studies have shown that the B chain of platelet-derived growth factor (PDGF) has an important role in atherogenesis. In this study we have investigated the contribution of PDGF-A chain in cholesterol-induced atherogenesis in the New Zealand White rabbit. High titers of antibodies to PDGF-AA or to platelet cytosolic protein (PCP) were induced in these animals by immunization against recombinant human PDGF-AA or human PCP. Rabbits were then fed a 0.25% to 1% cholesterol–containing diet for 10 weeks to induce atherosclerotic lesions; the rabbits were then humanely killed and perfusion-fixed and their aortas were removed. The extent of atherosclerosis in the thoracic aortas was determined by quantitative morphometry after staining with oil red O. The intimal and medial areas in histological sections taken at the level of the first intercostal branch were quantified by image analysis. Immunization against PDGF-AA and PCP, but not against adjuvant alone, resulted in rising titers of antibodies within 2 weeks, the levels of which reached a plateau by 8 weeks. The antibodies to PDGF-AA were isoform-specific, recognized both human and rabbit PDGF-AA, and neutralized the biological activity of PDGF-AA in vitro. Integrated plasma cholesterol levels were similar in both groups. Compared with nonimmune rabbits (n=10), animals immunized against PDGF-AA (n=10) or PCP (n=10) had significantly smaller areas of the aorta covered by atherosclerotic lesions (24.6±5.1% and 18.7±4.2%, respectively, vs 34.4±4.3%;
P
<0.05). This was associated with a reduced aortic intimal-medial area ratio in PDGF-AA–immunized (0.009±0.006) and PCP-immunized (0.025±0.017) rabbits than in nonimmune animals (0.159±0.066;
P
<0.05). These data suggest that PDGF-AA is actively involved in cholesterol-induced atherosclerosis in the rabbit.
Interaction of two lipid disorders in a large French-Canadian kindred.
Authors: Davignon J , Lussier-Cacan S , Gattereau A , Moll P P , Sing C F
Published: June 2011

This study investigates the pedigree of 508 individuals over five generations identified by an individual with hypertriglyceridemia, familial hypercholesterolemia, and a IIb lipoprotein electrophoretic phenotype. The sample of 378 living individuals studied extensively for risk factors and disease status was distributed among maternal (170) and paternal (176) relatives and the codescendants (32) of the index case. It was found that the distributions of the plasma lipid and lipoprotein abnormalities in the different subsets of the kindred were consistent with the presence of two separate hereditary lipid disorders: familial hypercholesterolemia on the paternal side and familial hyperprebetalipoproteinemia on the maternal side. This combination of disorders with a possible contribution from factors influencing glucose metabolism was associated with high frequency of hypercholesterolemia and its clinical manifestations and of cardiovascular morbidity among the codescendants. An interaction effect is suggested as an explanation for the unusually high prevalence of hyperlipidemia among the codescendants and for the presence of a IIb phenotype in the index case.
Overproduction of low density lipoproteins associated with coronary heart disease.
Authors: Kesaniemi Y A , Grundy S M
Published: June 2011

The turnover rates of low density lipoprotein-apolipoprotein (apoLDL) were determined in eight men with coronary heart disease (CHD) and seven men matched for age, weight, and plasma lipid levels who were used for controls. The CHD patients were normocholesterolemic (plasma cholesterol = 204 +/- 8 mg/dl sem) as were the control subjects (227 +/- 15 mg/dl). The concentrations of plasma LDL cholesterol and apoLDL were similar for the two groups. In contrast, the synthetic rates of apoLDL were higher in the CHD patients (20.0 +/- 1.8 mg/kg/day) than in the controls (12.9 +/- 1.1 mg/kg/day) (p less than 0.01). The ratios of protein-to-cholesterol in LDL averaged 19% higher in the CHD patients. These patients with CHD maintained normal LDL levels despite an over-production of apoLDL because of an increased capacity for LDL removal; their fractional catabolic rates of apoLDL averaged 43% higher than those of the controls. These findings indicate that some patients with CHD have abnormalities in the turnover of apoLDL, even with normal concentrations of LDL; these abnormalities may contribute to accelerated atherosclerosis.
Remnants of lipoproteins of intestinal and hepatic origin in familial dysbetalipoproteinemia.
Authors: Kane J P , Chen G C , Hamilton R L , Hardman D A , Malloy M J , Havel R J
Published: June 2011

We used the low molecular weight form of apolipoprotein B (B-48) as a marker for the identification of remnant particles formed from chylomicrons in the plasma of patients with familial dysbetalipoproteinemia. In the serum of patients fasted 14 hours, the d less than 1.006 g/cm3 lipoproteins of prebeta mobility, separated by starch block electrophoresis, contained only the primary hepatogenous species of apolipoprotein B (B-100), and their lipid composition resembled that of normal prebeta very low density lipoproteins. In contrast, the fraction with beta mobility contained both the B-48 and B-100 proteins; the B-48 protein was found primarily among the largest particles. All fractions of beta mobility were greatly enriched with cholesteryl esters. The beta fraction thus contains remnant particles which appear to originate both from chylomicrons and hepatogenous very low density lipoproteins. It appears that these remnant particles share a common removal mechanism which is impaired in familial dysbetalipoproteinemia.
Age-related changes in composition and mechanical properties of the tunica media of the upper thoracic human aorta.
Authors: Spina M , Garbisa S , Hinnie J , Hunter J C , Serafini-Fracassini A
Published: June 2011

A cylindrical segment, free of complex atherosclerotic lesions, was resected at autopsy from each of 59 descending human thoracic aortas by cutting just below the level of the first pair of intercostal arteries and 35 mm distal to this incision. Each isolated tunica media was defatted and subjected to successive treatment with EDTA-Tris, 5 M guanidine hydrochloride-Tris, 5 M guanidine hydrochloride-Tris-DTE, collagenase and either trypsin or hot alkali. After each extraction or digestion, the dimensions and weight of the segments were measured and the extracted materials were analyzed and quantitated. This allowed the total content of the various components of the tunica media to be assessed by both gravimetric and analytical means. An age-related rise was observed in the total content of the following components: proteins and glycoproteins soluble in chaotropic solvents (ranging from 24 mg/cm in the youngest samples to 46 mg/cm in the oldest) and collagen (38 mg/cm to 69 mg/cm). In contrast, the total content of elastin remained constant at 70 mg/cm at all ages, but its concentration decreased due to the rise in the concentration of the other tissue components as the tunica media thickened with age. It was also noted that with increasing age there was an accumulation of protein(s) which could not be solubilized by extraction with chaotropic agents or with collagenase, but which could be removed by treatment with either trypsin or hot alkali. Mechanical measurements conducted before and after trypsin digestion on samples previously subjected to purification with the first four agents used suggest that this accumulated protein(s) influenced the elastic response of the tissue to the applied stress by increasing the incremental modulus, the breaking stress, and the hysteresis. After the removal of this additional protein(s), the mechanical behavior of the elastin component was found to be identical in all samples, irrespective of age. It is therefore proposed that the morphological changes and the stiffening observed in the aging aortic wall are not due to degradation of its elastin network but to variations in the supramolecular organization of connective tissue components.
Hyperlipidemia in the Pacific Northwest Bell Telephone Company Health Survey. Part 1. Lipoprotein cholesterol and triglyceride concentrations.
Authors: Walden C E , Wahl P W , Knopp R H , Warnick G R , Ogilvie J T , Hazzard W R , Hoover J J , Albers J J
Published: June 2011

Lipoprotein triglyceride and cholesterol concentrations and characteristics are described in normolipidemic and in three categories of hyperlipidemic subjects participating in the Pacific Northwest Bell Telephone Company Health Survey. For this study, 350 white participants 20 to 59 years of age with cholesterol or triglyceride values exceeding the age, sex, and hormone-use specific, population-based 90th percentile values were defined as having hypercholesterolemia, hypertriglyceridemia, or combined hyperlipidemia; 722 participants were classified as normolipidemic. In hypercholesterolemia, very low density lipoprotein cholesterol and triglyceride and high density lipoprotein cholesterol concentrations were higher than in normolipidemia. In hypertriglyceridemia, high density lipoprotein cholesterol was significantly lower in men and women not using sex hormones and low density lipoprotein triglyceride was significantly higher in men and women using hormones compared to normolipidemia. In combined hyperlipidemia, high density lipoprotein cholesterol concentrations were lower than in normolipidemia, but higher than in pure hypertriglyceridemia. The presence of beta migrating very low density lipoprotein and chylomicrons was seen primarily in hypertriglyceridemic or combined hyperlipidemic men. Sinking prebeta lipoprotein was equally common (20%) among all normolipidemic and hypercholesterolemic subjects, but was less common (5% to 10%) in hypertriglyceridemic and combined hyperlipidemic men and female hormone users. Quantitative and qualitative lipoprotein abnormalities associated with hyperlipidemia were found to vary by gender and by sex hormone use in women and were often, but not always, more marked in men.
Racial differences in platelet survival time in patients with symptomatic coronary atherosclerosis.
Authors: Thomas L C , Giles T D , Stuckey W J , Mautner R K , Iteld B J
Published: June 2011

Platelet survival times were studied in 40 patients (21 white and 19 black) with coronary artery disease and stable effort induced angina pectoris. The platelet survival times of 19 white controls (9.27 +/- 0.49 days; mean +/- SD) were not significantly different from those of 12 black controls (8.88 +/- 0.81 days), and the platelet survival times for 21 white patients with coronary artery disease (8.46 +/- 0.65 days) were lower than the times for both the white controls (p less than 0.01) and the combined control group (p less than 0.01). However, the difference between the mean platelet survival times of 19 black patients (9.22 +/- 0.68) and the control groups was not significant, and the difference between the mean platelet survival times of the 21 white patients and the 19 black patients was significant (p less than 0.01). Stepwise multiple linear regression analysis indicated that race was the most significant factor in predicting shortened platelet survival (r = 0.4783; p less than 0.01). It is concluded that racial background should be considered in the interpretation of platelet studies and that reported racial differences in the rate and extent of atherosclerotic lesions may be related to racial differences in platelet consumption.
Interaction of platelets and fibrin with injured rabbit aortic neointima. Effect of prostaglandin I2 and heparin.
Authors: Adelman B , Stemerman M B , Handin R I
Published: June 2011

Following aortic balloon deendothelialization, rabbits develop a neointima composed of smooth muscle cells and extracellular connective tissue. Injury of this neointima with a balloon catheter results in the accumulation of platelet aggregates and fibrin on the vessel surface. We studied platelet attachment and secretion following injury of the neointima and also the effect of prostaglandin I2 (PGI2) and heparin on these events. Platelet factor 4 was detected within the neointima by indirect immunofluorescence 30 minutes after neointimal injury. By using 51Cr-labeled platelets, it was possible to quantitate total platelet attachment following neointimal injury. When animals were sacrificed 30 minutes after reinjury, there were 4.46 X 10(6) platelets/cm2 of aortic surface in animals injured 10 days after initial balloon deendothelialization, and 3.75 X 10(6) platelets/cm2 of aortic surface in animals injured 29 days after initial injury. In these two groups, infusion of 850 ng/kg/min PGI2, along with a single infusion of 2500 units of heparin, inhibited fibrin deposition and reduced platelet attachment by 71% and 76%, respectively. Although infusion of heparin alone prevented fibrin deposition, neither heparin nor PGI2 individually reduced platelet attachment as profoundly as did their combined use.
Increased low density lipoprotein production associated with obesity.
Authors: Kesaniemi Y A , Grundy S M
Published: June 2011

Turnover rates of the apolipoprotein of low density lipoproteins (apoLDL) and cholesterol balance were determined in six obese men and six control men. The two groups were of similar age and matched for apoLDL concentrations. Levels of plasma total cholesterol in obese patients (209 +/- 14 SEM mg/dl) were similar to controls (225 +/- 17 mg/dl). LDL-cholesterol was numerically but not statistically lower in obese subjects (111 +/- 18 mg/dl) compared to controls (145 +/- 13 mg/dl). Synthetic rates of apoLDL in contrast were higher in obese patients (1450 mg/day) than in controls (934 mg/day) (p less than 0.002). Three factors could explain the similar concentrations of LDL-cholesterol in obese and control subjects, despite overproduction of apoLDL in the obese. First, LDL was diluted into a larger plasma pool in obese patients; second, fractional catabolic rates of apoLDL were somewhat greater in obese men than in controls; and third, obese patients had higher ratios of protein-to-cholesterol in LDL. The production of apoLDL for all patients was not correlated with total body synthesis of cholesterol. The major finding of this study was that obese patients have increased turnover of apoLDL, not necessarily reflected by high concentrations of LDL-cholesterol. This high turnover rate itself may raise the risk for coronary heart disease in obese patients.
Dietary fat saturation and hepatic acylcoenzyme A:cholesterol acyltransferase activity. Effect of n-3 polyunsaturated and long-chain saturated fat.
Authors: Johnson M R , Mathur S N , Coffman C , Spector A A
Published: June 2011

The acylcoenzyme A:cholesterol acyltransferase (ACAT) activity in liver microsomes from rats fed a diet containing 14% menhaden oil (Mp) for 11 days was 117% higher than that in microsomes from rats fed a corresponding diet containing 14% cocoa butter (Ms). There were no differences in the cholesterol and phospholipid contents of Mp and Ms or in the activities of palmitoyl coenzyme A hydrolase and NADPH cytochrome c reductase. NADPH-dependent lipid peroxidation was higher in Mp, whereas glucose 6-phosphatase activity was higher in Ms. These findings indicate that the ACAT response to differences in dietary fat saturation is not due to a nonspecific effect of these diets on microsomal enzymes. When 1% cholesterol was added to the diets, the cholesterol content and ACAT activity of both microsomal preparations increased, but the ACAT activity of Mp remained 60% higher than that of Ms. Addition of cholesterol by incubation of the microsomes with liposomes also increased ACAT activity. At corresponding cholesterol contents, however, the ACAT activity of Mp remained 50% to 70% above that of Ms. There was no difference in the plasma cholesterol concentration in the two groups of rats, indicating that the ACAT effect probably is not due to a difference in the amount of circulating cholesterol available to the liver. Mp contained 40% more polyunsaturated fatty acids and five times more n-3 polyunsaturates than Ms. These findings suggest that the increase in ACAT activity in Mp is due, at least in part, to the difference in the fatty acid composition of the microsomes.
Joint distribution of lipoprotein cholesterol classes. The Framingham study.
Authors: Abbott R D , Garrison R J , Wilson P W , Epstein F H , Castelli W P , Feinleib M , LaRue C
Published: June 2011

During the period 1971 to 1975, the cholesterol content of lipoprotein density classes were measured in 2415 male and female Framingham Heart Study participants and 4342 of their offspring and offspring spouses who were free of coronary heart disease. In this first of three papers, the univariate and bivariate distributions of high density lipoprotein cholesterol, low density lipoprotein cholesterol, and very low density lipoprotein cholesterol are presented. There are differences in the levels of lipoprotein cholesterols by age, gender, and use of hormone preparations. The bivariate cross-tabulations of the three pairs of lipoprotein cholesterol measurements exhibit properties that cannot be appreciated from univariate summary statistics and suggest the importance of joint consideration of different lipoprotein cholesterol patterns for assessing the risk of coronary heart disease.
Ibuprofen protects platelet cyclooxygenase from irreversible inhibition by aspirin.
Authors: Rao G H , Johnson G G , Reddy K R , White J G
Published: June 2011

Previous investigations have shown that ibuprofen inhibits the second wave of platelet aggregation and blocks the conversion of 14C-arachidonic acid to thromboxane. However, the influence of the drug on platelet function and cyclooxygenase is transitory, lasting only 24 hours. The present study has taken advantage of the short-lived influence of ibuprofen to study its interaction with the long-term effects of aspirin. As expected, both aspirin and ibuprofen suppressed platelet cyclooxygenase activity and function, but addition of aspirin to ibuprofen-treated platelets did not increase the degree of inhibition in vitro. Platelet function and prostaglandin synthesis recovered completely 26 hours following ingestion of ibuprofen, but remained compromised 26 hours after taking aspirin. When 650 mg of aspirin was administered after ibuprofen, platelet function and cyclooxygenase activity recovered as completely at 26 hours as did platelets which had been exposed to ibuprofen alone. Thus, prior exposure to ibuprofen in vivo completely protected cyclooxygenase from the irreversible effects of aspirin. Our findings indicate that ibuprofen-like indomethacin and other nonsteroidal antiinflammatory drugs react with the heme group of cyclooxygenase to prevent arachidonic acid conversion. Since ibuprofen completely blocks the effects of aspirin in platelets in vitro and in vivo, aspirin's primary influence on inhibition of cyclooxygenase must also be through action on the heme portion of the enzyme, rather than acetylation of the protein.
Morphometry of air-drying-induced arteriosclerosis in rat carotid artery. Effect of air-flow rate.
Authors: van Pelt-Verkuil E , van Pelt W , Jense D
Published: June 2011

Arteriosclerosis in the Wistar rat carotid artery was induced by air drying of the endothelium, a procedure that caused media necrosis. We describe a number of technical modifications that facilitate the procedure and minimize damage to the vessel wall (i.e., media necrosis). A morphometric study of vessel wall changes induced by endothelial denudation at various air-flow rates showed that necrosis of the inner medial layer and lesion size and position were constant at all flow rates used (greater than or equal to 28 ml/min). The extent of necrosis of the outer medial layers, the endothelial repair, and the shape of the lesions varied with the air-flow rate used. Since at an air-flow rate of 28 ml/min medial necrosis was minimal and myointimal lesion development was as extensive as at higher flow rates, we consider this air-flow rate to be optimal for this model of experimental arteriosclerosis. We hypothesize that the shape of the myointimal lesion is determined by the timespan of endothelial denudation and by the availability of smooth muscle cells in necrotic and normal media. Furthermore, the proliferation of the smooth muscle cells and their migration into the intima is probably dominant over the repopulation of the media by these cells.
Low density lipoprotein metabolism by endothelial cells from human umbilical cord arteries and veins.
Authors: van Hinsbergh V W , Havekes L , Emeis J J , van Corven E , Scheffer M
Published: June 2011

Binding and metabolism of low density lipoprotein (LDL) and acetylated LDL were examined in endothelial cells from human umbilical cord arteries and veins. Both high and low affinity LDL interactions were observed. High affinity LDL binding and catabolism were increased five- to sevenfold after preincubation for 18 hours in LPDS containing medium. Subconfluent cells degraded, endocytosed, and bound 1.5 to 2.7 times more LDL by high affinity interaction than confluent cells, when endothelial cell growth supplement (ECGS) was present in the culture system. In the absence of ECGS, these ratios were somewhat less. Low affinity LDL metabolism was less affected by the state of confluency. Binding of LDL and acetylated LDL by venous endothelial cells was more than two- and threefold, respectively, than that by comparable arterial cells. However, the difference in LDL binding was not reflected in an altered LDL catabolism. There apparently is a population of low affinity binding sites not involved in LDL catabolism. LDL metabolism was identical in cells, which were cultured in medium supplemented with 20% to 100% serum or hirudin- or heparin-treated platelet-poor plasma. Without preincubation in LPDS, high affinity adsorptive endocytosis mediated the main part of LDL uptake only at low LDL concentrations (5 to 20 micrograms protein/ml). However, at physiological LDL concentrations (550 micrograms/ml), we estimated that this process mediated only 17% of the LDL uptake. We calculated that fluid endocytosis and low affinity adsorptive endocytosis of LDL accounted for the remaining 12% and 70%, respectively, of the LDL uptake at physiological LDL concentrations.