bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of biologically active autacoids is regulated by calcium influx in endothelial cells.
Authors: Kruse H J , Grünberg B , Siess W , Weber P C
Published: June 2011

The blocker of receptor-mediated calcium entry SK&F 96365 was used to evaluate the contribution of calcium influx to the formation of biologically active endothelial prostanoids and endothelium-derived relaxing factor (EDRF). SK&F 96365 inhibited histamine-stimulated calcium entry into human umbilical vein endothelial cells but not its discharge from intracellular stores as determined spectrofluorometrically by changes of intracellular calcium concentration in fura-2-loaded cells. Concordantly, SK&F 96365 inhibited histamine-induced endothelial synthesis of 6-keto-prostaglandin F1 alpha and thromboxane B2 in a dose-dependent manner. To assess the functional significance of endothelial formation of prostacyclin and EDRF to platelets, the cAMP- and cGMP-dependent phosphorylation of two platelet proteins, rap1B and a 50-kD vasodilator-stimulated phosphoprotein (VASP), was analyzed in coincubation experiments of endothelial cells with platelets. Autacoids released by histamine-stimulated endothelial cells caused the phosphorylation of rap1B and VASP in platelets, which was only partly inhibited by either indomethacin or NG-monomethyl-L-arginine but was almost completely suppressed by SK&F 96365. The concomitant endothelial release of thromboxane A2 had no effect on protein kinase C- and calcium-dependent phosphorylation of platelet proteins. The results demonstrate that blockade of receptor-mediated calcium entry by SK&F 96365 markedly reduced the release of biologically active prostacyclin and EDRF from endothelial cells. Thus, calcium influx but not calcium release from intracellular stores plays a critical role in the receptor-stimulated formation and liberation of prostacyclin and EDRF in endothelial cells.
A perfusion chamber developed to investigate thrombus formation and shear profiles in flowing native human blood at the apex of well-defined stenoses.
Authors: Barstad R M , Roald H E , Cui Y , Turitto V T , Sakariassen K S
Published: June 2011

The precipitating event leading to stroke, myocardial infarction, and/or sudden death may be related to the formation of mural thrombus at the site of a ruptured or superficially damaged stenotic plaque. The fluid dynamic properties at atherosclerotic plaques that may be implicated in this thrombus formation have been described in a wide variety of model systems in both the process of plaque rupture and the growth of platelet thrombi. In general, the local fluid dynamic conditions are complex and show major variations from flow in well-defined laminar flow systems. However, no studies have attempted to quantify the effect of stenosis-related disturbances on thrombus formation in native human blood and to compare them with the local fluid dynamics. We developed a parallel-plate perfusion chamber device in which thrombus formation is measured at the "apex" of eccentric stenoses and have correlated such measurements with values of the local fluid dynamics obtained by computer simulation. The extent of stenoses (reduction in the cross-sectional area of the blood flow channel) was 60%, 80%, and 89%, corresponding to "apex" wall shear rates of 2600, 10,500, and 32,000 sec-1, respectively. The wall shear rate in the laminar flow region proximal and distal to the stenoses was 420 sec-1. The surface of the stenosis was purified collagen type III fibrils that were exposed to flowing nonanticoagulated human blood drawn directly from an antecubital vein by a pump placed distally to the perfusion chamber. The resulting blood-collagen interactions were quantified by light microscopy by using a morphometric image analysis technique. Under all conditions studied, platelet thrombus formation at the "apex" was extensive.(ABSTRACT TRUNCATED AT 250 WORDS)
Hyperlipidemia accelerates allograft arteriosclerosis (chronic rejection) in the rat.
Authors: Räisänen-Sokolowski A , Tilly-Kiesi M , Ustinov J , Mennander A , Paavonen T , Tikkanen M J , Häyry P
Published: June 2011

The relevance of hyperlipidemia in allograft arteriosclerosis (chronic rejection) is controversial. Isolated hypercholesterolemia induced with cholesterol-cholic acid-diet (CC-diet) or hypertriglyceridemia induced with glycerol-diet (G-diet) had no or only a protective effect on aortic allograft arteriosclerosis in the rat. Combined hyperlipidemia with both diets (CC+G-diet) enhanced allograft arteriosclerosis by doubling intimal thickness and cellularity (P < .05) but had no effect on host arteries. Compared with normolipidemic controls, the CC+G-diet increased the total serum cholesterol concentration 4.8-fold (P < .05). Levels of VLDL2 and IDL increased 4.8- and 18.1-fold (P < .05), and their composition changed from triglyceride-rich to cholesterol-rich lipoproteins in an atherogenic direction. The CC+G-diet had no effect on the structure of inflammation in the vascular wall. Instead, significant lipid deposits were observed, and the expression of epidermal growth factor and insulin-like growth factor-1 was significantly elevated in the vascular wall. Thus, elevations in VLDL and IDL lipoprotein levels and their cholesterol content associate with the generation of allograft arteriosclerosis in rats. Deposition of lipids in the vascular wall seems to induce local synthesis of certain growth factors, which ultimately leads to the induction of smooth muscle cell replication.
Dietary fat induces changes in factor VII coagulant activity through effects on plasma free stearic acid concentration.
Authors: Mitropoulos K A , Miller G J , Martin J C , Reeves B E , Cooper J
Published: June 2011

Previous studies have demonstrated activation of the contact system of coagulation and an increase in factor VII coagulant activity (VIIc) when citrated plasma is incubated in the presence of micellar stearate. The products of contact activation, factors XIIa and IXa, were responsible in this system for the activation of factor VII, thereby increasing factor VIIc. To obtain evidence that these in vitro interactions also operate in vivo, factor VIIc was examined in relation to plasma free fatty acid concentrations in five healthy individuals during the consumption of isocaloric high-saturated fat, high-unsaturated fat, and low-fat diets, each taken for 4 weeks in random order and separated by intervals of 12 weeks. For all but the final 3 days of each phase, subjects selected appropriate foods from prepared lists to meet the dietary requirements. Experimental diets of predetermined fat content and composition were fed on days 26 through 28 in each phase. Fat supplied on average 62% of energy in two of the experimental diets and less than 20% of energy in the third. On the final day of each dietary phase, the concentrations of the various free fatty acids and factor VIIc were measured before breakfast and at three 150-minute intervals thereafter. Plasma factor VIIc was, respectively, 6.5% and 13.1% of standard higher on the unsaturated and saturated fat diets than on the low-fat diet. Furthermore, the plasma concentration of stearic acid was strongly associated with factor VIIc (r = .58; P < .0001), and this relation remained significant (P = .003) after allowance for the plasma concentrations of palmitic, oleic, and linoleic acids.(ABSTRACT TRUNCATED AT 250 WORDS)
Tissue-factor pathway inhibitor and lipoproteins. Evidence for association with and regulation by LDL in human plasma.
Authors: Hansen J B , Huseby N E , Sandset P M , Svensson B , Lyngmo V , Nordøy A
Published: June 2011

Tissue-factor pathway inhibitor (TFPI) is a potent inhibitor of extrinsic coagulation, which is mainly associated with lipoproteins in circulating blood. Gel filtration of human plasma confirmed the presence of three peaks in which approximately 10%, 70%, and 20% of total TFPI activity was retained. Precipitation of very-low-density lipoproteins and low-density lipoproteins (LDLs) in plasma by polyethylene glycol almost completely abolished peaks and I and II. LDL isolated by ultracentrifugation revealed two peaks of TFPI after gel filtration that coeluted with peaks I and II, respectively, from gel filtration of total plasma. TFPI activity in peaks I and II was also precipitated by anti-apolipoprotein B antibodies. Fourteen patients with familial hypercholesterolemia had higher plasma TFPI activity than did age- and sex-matched normolipemic control subjects (1.45 +/- 0.27 U/mL versus 0.80 +/- 0.09 U/mL, P < .001). Plasma TFPI was correlated with LDL cholesterol (r = .73, P < .001) and apolipoprotein B (r = .69, P < .001). No association was found with high-density lipoprotein cholesterol or apolipoprotein A-I. In a double-blind, placebo-controlled trial among the familial hypercholesterolemia patients, lovastatin alone or in combination with fish oil concentrate lowered plasma TFPI in parallel with LDL cholesterol. Gel filtration of plasma from these patients demonstrated a specific drop in apolipoprotein B-TFPI complexes, whereas TFPI not associated with lipoproteins was unchanged. This study demonstrated that plasma TFPI was associated with and regulated by LDL in plasma from healthy subjects and patients with familial hypercholesterolemia.
Modification of LCAT activity and HDL structure. New links between cigarette smoke and coronary heart disease risk.
Authors: McCall M R , van den Berg J J , Kuypers F A , Tribble D L , Krauss R M , Knoff L J , Forte T M
Published: June 2011

The mechanism(s) through which smoking influences the progression of atherosclerosis is poorly understood. Recent evidence suggests that oxidants present in the gas phase of cigarette smoke are involved. We exposed human plasma to the filtered gas phase of cigarette smoke to assess its effects on plasma components involved in the antiatherogenic reverse cholesterol transport pathway. In our model, freshly isolated plasma (24 mL) was exposed to filtered air or gas-phase cigarette smoke for up to 6 hours at 37 degrees C. Lecithin-cholesterol acyltransferase (LCAT) activity was dramatically inhibited by cigarette smoke. A single 15-minute exposure to the smoke from an eighth of a cigarette was sufficient to reduce LCAT activity by 7%; additional exposures resulted in further decreases in activity. At 6 hours, only 22% of control LCAT activity remained in plasma exposed to smoke. Compared with control, gas-phase cigarette smoke-exposed plasma possessed high-density lipoprotein (HDL) with increased (16%) negative charge and with cross-linked apolipoproteins AI and AII. These data demonstrate that gas-phase cigarette smoke can inhibit a key enzyme (LCAT) and modify an integral lipid transport particle (HDL) that are essential components for the normal function of the reverse cholesterol transport pathway. Gas-phase cigarette smoke-induced modification of the reverse cholesterol transport pathway may provide a new mechanistic link between cigarette smoke and coronary heart disease risk.
Lipoproteins are major and primary mitogens and growth promoters for human arterial smooth muscle cells and lung fibroblasts in vitro.
Authors: Björkerud S , Björkerud B
Published: June 2011

Smooth muscle proliferation leading to excessive intimal thickening is of prime importance in atherosclerosis. Human arterial smooth muscle cells (SMCs) and human lung fibroblasts are rather insensitive to mitogens under plasma-free conditions in vitro. This prompted us to study the distribution and nature of the growth-promoting material in human plasma. SMCs were obtained from explants of human aortic media. More than 80% of the growth-promoting activity of plasma was present in the lipoprotein (LP) fraction. The growth-promoting capacity of the different LPs was determined on fractions isolated with density gradient ultracentrifugation. Cytotoxic effects appeared if low-density lipoprotein (LDL) was not protected from oxidation and were aggravated with platelet-derived growth factor (PDGF)-BB. Very-low-density lipoprotein, LDL, and high-density lipoprotein (HDL) stimulated DNA replication and cell growth by themselves. The stimulation was considerable and equaled that obtained with PDGF-BB only. It was strongly increased in the presence of PDGF-BB. The effect on SMCs was not uniform for subfractions of HDL. A light portion inhibited growth in the absence but strongly stimulated it in the presence of PDGF-BB. For fibroblasts, HDL subfractions had a uniform effect, suggesting a cell type-dependent difference. Addition of cholesterol or essential fatty acids did not induce a growth response similar to that of LPs. This speaks strongly against mere nutritional supplementation as responsible for the mitogenic and growth-promoting effect of LPs and suggests that the effect may be more specific. Disordered LP metabolism is strongly related to atherosclerosis, and certain LPs have a potential role for the deposition of lipids. In addition to this, the distinct mitogenic and growth-stimulating effect of LPs by themselves, as demonstrated in the present report, suggests a mechanism by which intimal thickening, which is a prerequisite for atherosclerosis, may be induced. The pronounced amplification of this effect with PDGF-BB, a substance that also has been implicated in atherogenesis, might promote growth leading to the excessive intimal thickening in the atherosclerotic plaque.
Influence of HDL subfractions on erythrocyte aggregation in hypercholesterolemic men. PCVMETRA Group.
Authors: Razavian S M , Atger V , Giral P , Cambillau M , Del-Pino M , Simon A C , Moatti N , Levenson J
Published: June 2011

Recent studies have suggested that rheological mechanisms may be involved in the pathogenesis of ischemic syndromes in hyperlipidemias. We investigated the association between erythrocyte aggregation and components of lipoproteins in the blood of 60 normotensive, hypercholesterolemic men aged 45 +/- 8 years. The rheological parameters assessed were aggregation index (AI) and disaggregation shear rate threshold (gamma t) as determined by laser reflectometry, plasma fibrinogen, total serum protein, and hematocrit. The lipoprotein variables included total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol and its subfractions HDL2 cholesterol and HDL3 cholesterol, apolipoprotein (apo) B, apoA-I, HDL particles containing apoA-I without apoA-II (LpA-I), and HDL particles containing both apoA-I and apoA-II (LpA-I/A-II). Covariables considered for possible confounding effects were age, body mass index, and smoking behavior. Fibrinogen, total serum protein, and both aggregation parameters (AI and gamma t) were elevated in this hypercholesterolemic population. Univariate analysis showed that both AI and gamma t correlated positively with fibrinogen (P < .001) and total serum protein (P < .01) and negatively with HDL2 cholesterol (P < .01) and LpA-I (P < .01); gamma t also provided a positive correlation with LpA-I/A-II (P < .05). A multivariate model analysis demonstrated that HDL2 cholesterol, LpA-I, and LpA-I/A-II also emerged as significant factors influencing erythrocyte aggregation; 60% to 68% of the variance of AI and 47% to 64% of the variance of gamma t could be explained by these factors.(ABSTRACT TRUNCATED AT 250 WORDS)
Time course of the effects of a single bolus injection of F(ab')2 fragments of the antiplatelet GPIIb/IIIa antibody 7E3 on arterial eversion graft occlusion, platelet aggregation, and bleeding time in dogs.
Authors: Kiss R G , Lu H R , Roskams T , Jang I K , Plow E F , Gold H K , Collen D
Published: June 2011

The time course of the effects of a single intravenous bolus injection of 10 mg/kg aspirin or 0.8 mg/kg F(ab')2 fragments of the monoclonal antiplatelet glycoprotein IIb/IIIa receptor antibody 7E3 [7E3-F(ab')2] on arterial occlusion, platelet aggregation, and bleeding time was studied in 30 dogs with an everted (inside out) carotid arterial segment inserted into the femoral artery. In the absence of an antiplatelet agent, the eversion grafts occluded spontaneously with platelet-rich thrombus within 30 minutes. With aspirin, arterial occlusion persisting for 2 hours occurred in 5 of 10 dogs and cyclic occlusion and reflow in 4 animals; arterial occlusion was observed in all dogs at 24 hours. With 7E3-F(ab')2, arterial patency persisted throughout a 2-hour observation period in all of 10 dogs and for 24 hours in 4 of the 10 dogs. Contralateral eversion grafting 24 hours after aspirin or 7E3-F(ab')2 injection was associated with graft patency for 2 hours in 1 of 5 aspirin dogs and in 3 of 5 7E3-F(ab')2 dogs; patency persisted for 24 hours. In dogs grafted 48 hours after aspirin or 7E3-F(ab')2 injection, patency at 24 hours was seen in 0 of 5 dogs given aspirin and 3 of 5 dogs given 7E3-F(ab')2. The overall frequencies of arterial graft patency at 2, 24, 48, and 72 hours after study drug injection were significantly higher in the 7E3-F(ab')2 groups than in the aspirin groups (P < .0005, n = 10 in each group; P < .05, n = 15; P < .005, n = 15; and P = .05, n = 5, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
Platelet LDL receptor recognizes with the same apparent affinity both oxidized and native LDL. Evidence that the receptor-ligand complexes are not internalized.
Authors: Pedreño J , de Castellarnau C , Cullaré C , Ortín R , Sánchez J L , Llopart R , González-Sastre F
Published: June 2011

We have recently demonstrated that the platelet low-density lipoprotein (LDL) receptor is immunologically different from the "classic" receptor of nucleated cells. We undertook the current studies to investigate the interaction of this receptor with oxidized LDL and to determine whether an endocytosis-mediated response is involved in the binding of LDL to platelets. The platelet LDL receptor recognized with the same affinity both native and oxidized LDL particles (IC50, 0.045 and 0.054 g/L; Kd, 45.8 and 65.9 nmol/L, respectively). The Hill coefficients of the displacement of 125I-LDL binding were -1.10 and -1.05 for unlabeled native and oxidized LDL, respectively, thereby suggesting a single set of binding sites. To ascertain whether human platelets bind oxidized LDL, we performed ligand binding assays with 125I-oxidized LDL. Saturation curves of 125I-oxidized LDL binding at 22 degrees C showed that human platelets bound these modified particles to a class of saturable binding sites, numbering approximately 3895 +/- 241 per platelet with a dissociation constant (Kd) of 96.2 +/- 10.3 nmol/L. Displacement experiments showed that 125I-oxidized LDL binding was inhibited with the same affinity by both oxidized and native LDL (IC50, 0.055 and 0.065 g/L; Kd, 88 and 64 nmol/L, respectively). The Hill coefficients of the displacement of the 125I-oxidized LDL binding were -1.02 and -1.07 for unlabeled oxidized and native LDL, respectively, suggesting that a single set of binding sites is implicated. Moreover, oxidized LDL- at a protein concentration of 0.5 g/L enhanced ADP- and collagen-induced platelet aggregation in a manner similar to native LDL.(ABSTRACT TRUNCATED AT 250 WORDS)
Chronic exposure of cultured bovine endothelial cells to oxidized LDL abolishes prostacyclin release.
Authors: Thorin E , Hamilton C A , Dominiczak M H , Reid J L
Published: June 2011

We investigated the effect of chronic exposure (3 days) with low-density lipoprotein (LDL) and oxidized (Ox)-LDL on the unstimulated and stimulated formation of prostacyclin (6-keto-prostaglandin [PG]F1 alpha) and total inositol phosphates (IPs) by cultured bovine aortic endothelial cells. Neither basal nor bradykinin-stimulated (1 to 10 nmol/L) formation of 6-keto-PGF1 alpha was affected by LDL, except at the highest concentration of bradykinin tested (100 nmol/L). In the presence of the antioxidants N-acetyl-L-cysteine (NAC, 10 mumol/L) or vitamin E (100 mumol/L), basal and bradykinin-stimulated formation of 6-keto-PGF1 alpha was potentiated by 20 micrograms protein/mL of LDL. Ox-LDL decreased unstimulated formation of the eicosanoid from 3.1 +/- 0.2 pg/micrograms protein in control cells to 1.6 +/- 0.1 and 0.5 +/- 0.1 pg/microgram protein after 3-day incubation with 5 and 20 micrograms protein/mL of Ox-LDL, respectively (P < .05). As in the basal state, Ox-LDL decreased bradykinin-induced 6-keto-PGF1 alpha formation. NAC or vitamin E did not influence Ox-LDL-induced endothelial cell changes in eicosanoid production. IPs formation by endothelial cells increased to a similar extent in the presence of 20 micrograms protein/mL of either LDL or Ox-LDL. However, no change was apparent in the bradykinin (10 mumol/L)-induced increase in total IPs formation after incubation with the lipoproteins. The data indicate that chronic exposure to Ox-LDL abolishes the production of prostacyclin by cultured endothelial cells. The oxidatively modified lipoprotein seems to more specifically affect the prostacyclin pathway.(ABSTRACT TRUNCATED AT 250 WORDS)
Vitamin E protects against impairment of endothelium-mediated relaxations in cholesterol-fed rabbits.
Authors: Stewart-Lee A L , Forster L A , Nourooz-Zadeh J , Ferns G A , Anggård E E
Published: June 2011

The vascular effects of dietary vitamin E were investigated in isolated carotid artery preparations from cholesterol-fed New Zealand White rabbits. Rabbits were fed either a control, 1% cholesterol, or 1% cholesterol plus 0.2% vitamin E diet for 4 weeks. In raised-tone preparations, relaxant responses to acetylcholine were enhanced in rabbits fed cholesterol plus vitamin E, reversing the reduction in responses measured in preparations from cholesterol-fed rabbits. Relaxant responses to the calcium ionophore A23187 were significantly enhanced in cholesterol plus vitamin E-fed rabbits compared with those fed cholesterol alone, with no difference between control and cholesterol-fed rabbits. Relaxant responses to sodium nitroprusside were not different between the three dietary groups. Constrictor responses to noradrenaline and serotonin in isolated carotid artery preparations at basal tone were unaltered after cholesterol and cholesterol plus vitamin E diets. The copper-induced oxidation of beta-very-low-density lipoproteins (beta VLDL) isolated from plasma of rabbits fed a cholesterol plus vitamin E diet was almost completely inhibited compared with the oxidation of beta VLDL from rabbits fed cholesterol alone. These results show that vitamin E prevents endothelial dysfunction associated with cholesterol feeding and suggests that vitamin E may be beneficial in preventing functional impairment associated with atherosclerosis.
ApoB metabolism in familial hypercholesterolemia. Inconsistencies with the LDL receptor paradigm.
Authors: Fisher W R , Zech L A , Stacpoole P W
Published: June 2011

The biology of the low-density lipoprotein (LDL) receptor has been examined in detail, and a paradigm for LDL metabolism has evolved from comparative studies of cholesterol metabolism in a variety of cells cultured from normal individuals and subjects with familial hypercholesterolemia (FH). Cultured cells from patients with homozygous FH lack a functional LDL receptor and show diminished LDL clearance, induction of the enzyme hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase, increased cholesterol synthesis, decreased cholesterol ester production, and depleted cholesterol ester stores. The observed decrease in the fractional catabolic rate (FCR) of LDL is attributed to the mutated LDL receptor gene. However, in the experimental animal model of this disease, the Watanabe heritable hyperlipidemic (WHHL) rabbit, cholesterol ester stores are increased, while hepatic cholesterol synthesis is decreased. Furthermore, in humans HMG-CoA reductase is suppressed, and the LDL apolipoprotein (apo) B production rate is increased in patients with FH. These findings raise questions about the adequacy of the paradigm in understanding hepatic cholesterol metabolism in vivo. In humans, apoB metabolism is believed to be principally determined by the liver, where apoB is both synthesized and catabolized. Assuming the neutral lipid content of the liver is the major determinant of apoB metabolism, we postulated that the changes in apoB metabolism in FH are predictable when based on the assumption of an increase in hepatic cholesterol and cholesterol ester content, as observed both in the WHHL rabbit and in humans. We examined this hypothesis in vivo in patients with heterozygous FH by using tracer kinetic methodology and have used similar data from normal and hypertriglyceridemic (HTG) subjects as controls. Whereas normal and HTG subjects secrete apoB primarily as large, triglyceride-enriched very-low-density lipoprotein (VLDL), heterozygous FH patients have an absolute decrease in apoB production and secrete almost 40% of apoB as smaller intermediate-density lipoprotein (IDL)/LDL. In normal humans, about half of secreted apoB is catabolized rather than being converted to LDL. In HTG subjects two thirds of apoB follows this same route, by which VLDL remnants remaining after triglyceride hydrolysis are largely returned to the liver. In contrast, in FH subjects secreted apoB is fully converted to LDL. Thus, although total apoB secretion is reduced in FH subjects, total LDL production is greater than in either normal or HTG subjects. Under basal conditions the elevated LDL in heterozygous FH is due to both decreased LDL receptor-mediated catabolism and increased LDL production. However, the number of LDL receptors actually expressed is suppressed below the number of potentially functional receptors.(ABSTRACT TRUNCATED AT 400 WORDS)
The human apolipoprotein(a)/plasminogen gene cluster contains a novel homologue transcribed in liver.
Authors: Byrne C D , Schwartz K , Meer K , Cheng J F , Lawn R M
Published: June 2011

Lipoprotein(a) is an atherogenic lipoprotein whose function and plasma concentration reflect the structure and regulation of the apolipoprotein(a) gene. Apolipoprotein(a) is a close homologue of plasminogen, and their genes are tightly linked on chromosome 6. To further characterize these genes, we analyzed overlapping human genomic yeast artificial chromosome clones, which revealed a cluster of four highly homologous genes encoding apolipoprotein(a), plasminogen, and two apolipoprotein(a)-related genes (rg) or pseudogenes. Hybridization analysis and reverse transcriptase polymerase chain reaction showed that one of these novel genes, designated apolipoprotein(a)rg-C, has a domain structure similar to apolipoprotein(a) and is transcribed in human liver. Three additional homologues designated as plasminogen-related genes are shown to be unlinked to this gene cluster and reside on chromosomes 2 and 4.
Regulation of serum cholesterol level in middle-aged and elderly men. Relation of cholesterol absorption and synthesis to lipoprotein metabolism.
Authors: Gylling H , Strandberg T , Tilvis R , Miettinen T A
Published: June 2011

The aim of the present study was to investigate cholesterol absorption and cholesterol and bile acid synthesis and relate these values of kinetics of low-density lipoprotein (LDL) apoprotein (apo) B in 50- and 75-year-old men to find out why and by which mechanism serum cholesterol level decreases with advancing age under normal home-living conditions. The daily calorie, fat, and cholesterol intakes were lower in the 75-year-old men because the physiological requirements of daily energy are reduced in old age. However, absolute body weight was identical in the two groups, indicating isocaloric energy intake. Serum levels of total and LDL cholesterol were insignificant lower but those of LDL apo B significantly lower, so that the LDL cholesterol/apo B ratio was higher in the elderly men. The mean reduction of LDL apo B by 26% (P < .05) in the old men was associated with a 30% (P < .05) decrease in transport rate (TR) and a 3% (P = NS) decrease in removal (FCR) for LDL apo B. However, at the comparable apo B levels, both TR and FCR for apo B were significantly lower in the old than in the younger men. Cholesterol absorption efficiency, bile acid synthesis, fecal neutral and total sterol excretion, and cholesterol turnover but not synthesis were reduced in the elderly men.(ABSTRACT TRUNCATED AT 250 WORDS)
Annexin V inhibits the procoagulant activity of matrices of TNF-stimulated endothelium under blood flow conditions.
Authors: van Heerde W L , Sakariassen K S , Hemker H C , Sixma J J , Reutelingsperger C P , de Groot P G
Published: June 2011

A human ex vivo thrombosis model was used to investigate whether recombinant annexin V (rANV) can prevent thrombus formation under venous and arterial blood flow conditions. In this model, blood from an antecubital vein of healthy donors was allowed to flow directly over the extracellular matrix of tumor necrosis factor-stimulated endothelial cells (TNF-ECMs). TNF-ECMs were preincubated with rANV (2.9 mumol/L) for 30 minutes. With this rANV concentration all binding sites present on TNF-ECMs (1.6 +/- 0.5 x 10(12)/cm2) are occupied, and a maximal inhibition was observed in a tissue factor-dependent clotting assay. Fibrin deposition and platelet and leukocyte adhesion were measured on the rANV-treated and nontreated TNF-ECMs. Nontreated TNF-ECMs were used as controls. rANV inhibited fibrin deposition by 81% at a wall shear rate of 100 s-1. A nonsignificant inhibition was also observed at 650 s-1. Platelet-matrix adhesion, which is more prominent at higher shear rates, was significantly decreased by 60% at 100 s-1 but not at 650 s-1. The average leukocyte adherence was nonsignificantly lowered at 100 s-1. Virtually no leukocytes adhered at 650 s-1. The results demonstrated that rANV can inhibit blood coagulation under venous blood flow conditions and may serve as an antithrombotic drug.
Induction of LDL receptor-related protein during the differentiation of monocyte-macrophages. Possible involvement in the atherosclerotic process.
Authors: Watanabe Y , Inaba T , Shimano H , Gotoda T , Yamamoto K , Mokuno H , Sato H , Yazaki Y , Yamada N
Published: June 2011

The low-density lipoprotein receptor-related protein (LRP) is a multifunctional receptor that binds to apolipoprotein E-rich lipoproteins, lipoprotein lipase, alpha 2-macroglobulin, lactoferrin, and tissue plasminogen activator. We studied the mRNA expression of LRP in human monocyte-derived macrophages and THP-1 cells. mRNA expression of LRP was induced during cell differentiation from human monocytes to macrophages or after incubation with phorbol ester (tetradecanoylphorbol acetate 100 ng/mL) in THP-1 cells, and the addition of 30 ng/mL macrophage colony-stimulating factor further enhanced LRP expression. These results indicated that the expression of LRP depended on the stage of differentiation and maturation of monocytic cells. mRNA expression of LRP was also enhanced in human monocyte-derived macrophages in the presence of acetylated low-density lipoprotein and in aorta of rabbits fed a high-cholesterol diet. We hypothesize that the LRP induced in monocyte-derived macrophages is involved in the initial process of atherosclerosis by interacting with its multiple ligands.
Lipoprotein abnormalities in non-insulin-dependent diabetic patients with impaired extrahepatic insulin sensitivity, hypertension, and microalbuminuria.
Authors: Zambon S , Manzato E , Solini A , Sambataro M , Brocco E , Sartore G , Crepaldi G , Nosadini R
Published: June 2011

We investigated whether specific lipoprotein abnormalities are present in non-insulin-dependent diabetes mellitus (NIDDM) patients with hypertension and/or microalbuminuria. Fifteen normotensive normoalbuminuric (H-M-), 32 hypertensive normoalbuminuric (H+M-), and 22 hypertensive microalbuminuric (H+M+) NIDDM patients and 20 sex-, age-, and weight-matched nondiabetic control subjects were studied. Lipoprotein size was measured by nondenaturing polyacrylamide gradient gel electrophoresis; insulin sensitivity was assessed by using a euglycemic hyperinsulinemic clamp and [6,6(2)H]glucose tracer infusion for simultaneous measurement of hepatic glucose output and whole-body glucose utilization. Total plasma and very-low-density lipoprotein cholesterol were higher in H+M+ than in control subjects (5.84 +/- 0.98 versus 4.97 +/- 0.98 and 0.57 +/- 0.54 versus 0.26 +/- 0.21 mmol/L, mean +/- SD, P < .05). Plasma triglycerides were higher in H+M+ than in either control or H-M- subjects (2.17 +/- 1.32 versus 1.18 +/- 0.67 and 1.30 +/- 0.59 mmol/L, respectively; P < .05). The mean low-density lipoprotein diameter was 27.2 +/- 0.8 in control, 26.7 +/- 0.8 in H-M-, 26.5 +/- 0.8 nm in H+M- (P < .05 versus control subjects), and 26.0 +/- 0.8 nm in H+M+ subjects (P < .05 versus control subjects). The mean cholesterol level of the large high-density lipoprotein particles was lower in H+M- and H+M+ (0.37 +/- 0.14 and 0.36 +/- 0.16 mmol/L) than in control and H-M- (0.54 +/- 0.41 and 0.54 +/- 0.27 mmol/L, P < .05) subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
Cell compositions of coronary and aortic atherosclerotic lesions in WHHL rabbits differ. An immunohistochemical study.
Authors: Shiomi M , Ito T , Tsukada T , Yata T , Ueda M
Published: June 2011

This study investigated whether coronary atherosclerosis was different from aortic atherosclerosis in Watanabe heritable hyperlipidemic rabbits. Atherosclerotic lesions were immunohistochemically stained by using a monoclonal antibody for rabbit macrophages (RAM-11) and a monoclonal antibody for muscle actin (HHF35) and were also subjected to conventional staining. The areas of the major lesional components, ie, macrophages, smooth muscle cells, collagen fibers, and extracellular lipid deposits, were measured with a color image analyzer. The percent macrophage area in coronary lesions was significantly lower compared with aortic lesions at all stages (early fatty streak, transitional, and advanced), while the percent smooth muscle cell area and collagen area were significantly higher in early fatty streak lesions of the coronary arteries. In addition, the macrophage area/smooth muscle cell area ratio was significantly lower in coronary lesions compared with aortic lesions at all stages. In conclusion, coronary atherosclerosis had a small number of macrophages and was rich in smooth muscle cells, whereas aortic atherosclerosis showed the opposite features. These results suggested that the role of macrophages and smooth muscle cells in the initiation and/or progression of coronary atherosclerosis differs from the role of these cells in aortic atherosclerosis.
Aging and genetic variation of plasma apolipoproteins. Relative loss of the apolipoprotein E4 phenotype in centenarians.
Authors: Louhija J , Miettinen H E , Kontula K , Tikkanen M J , Miettinen T A , Tilvis R S
Published: June 2011

We determined the common polymorphism of apolipoprotein E (E2, E3, and E4), apolipoprotein B Xba I polymorphism, and apolipoprotein C-III Sst I polymorphism in almost all Finnish centenarians alive in 1991 (n = 179/185). Plasma lipid and lipoprotein levels in different apolipoprotein genotypes were also measured. In comparison with younger Finnish populations studied previously, the frequency of the apolipoprotein E epsilon 2 allele was almost twice as high (7.0% versus 4.1%; P < .05) and that of the epsilon 4 allele only approximately one third as high (8.4% versus 22.7%; P < .001) in the centenarians. Plasma cholesterol and high-density lipoprotein cholesterol levels tended to be lowest in the group with the epsilon 2 allele (4.33 mmol/L and 1.41 mmol/L, respectively), intermediate in those with the epsilon 3 allele (4.57 mmol/L and 1.48 mmol/L, respectively), and highest in those with the epsilon 4 allele (4.82 mmol/L and 1.60 mmol/L, respectively). The frequencies of the apolipoprotein B X1 and X2 alleles (Xba I restriction site absent or present, respectively) among the centenarians and among the young Finns were not significantly different, whereas the apolipoprotein C-III S2 allele (Sst I restriction site present) occurred more often in the centenarians (frequency, 12.9%) than in the youngest reference population (frequency, 8.8%; P < .05). Centenarians with the apolipoprotein B X2X2 genotype and apolipoprotein E4 phenotype had a higher mean plasma cholesterol level than those with the X1X1 genotype and E2 phenotype (5.24 versus 3.43 mmol/L; P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)
DNA variants at the LPL gene locus associate with angiographically defined severity of atherosclerosis and serum lipoprotein levels in a Welsh population.
Authors: Mattu R K , Needham E W , Morgan R , Rees A , Hackshaw A K , Stocks J , Elwood P C , Galton D J
Published: June 2011

Coronary artery disease (CAD) patients (n = 235), comprising minimal (CAD-, n = 124) and severe (CAD+, n = 111) CAD, were recruited on the basis of their angiographic scores. Male control subjects (n = 123) were selected randomly from the Caerphilly Heart Study cohort. Subjects were genotyped for the Ser447-Ter mutation and HindIII/Pvu II restriction fragment length polymorphisms of the lipoprotein lipase gene and investigated for associations with severity and development of CAD and lipid and lipoprotein levels. The Ser447-Ter mutation showed no significant associations with CAD or dyslipidemia but was related to favorable lipid and lipoprotein profiles. The H2H2 genotype (P < .05) and H2 allele (P = .05) were significantly more frequent in CAD+ versus CAD- and control subjects versus CAD-. H2H2 subjects, among the entire male cohort, had significantly higher levels of apolipoprotein B (P = .0002), total cholesterol (P < .004), and triglycerides (P < .04) than alternative genotypes. P2P2 associated with significantly lower high-density lipoprotein cholesterol levels (P < .01). The H2 allele had most significant associations with raised apolipoprotein B levels compared with other biochemical parameters. Our data suggest that the H2 allele may be a linkage marker for an etiologic mutation for dyslipidemia and the severity and development of atherosclerosis; this is not the Ser447-Ter mutation.
Platelet activation results in a redistribution of glycoprotein IV (CD36).
Authors: Michelson A D , Wencel-Drake J D , Kestin A S , Barnard M R
Published: June 2011

To investigate the possibility that thrombin and/or other platelet activators change the platelet surface expression of glycoprotein IV (GPIV, CD36), we used a panel of five GPIV-specific monoclonal antibodies (OKM5, 5F1, FA6-152, 8A6, and F13) directed against different epitopes. All these antibodies bound to resting platelets in a concentration-dependent and saturable manner, as determined by flow cytometry of washed platelets. Thrombin (1 U/mL) induced an approximately twofold increase in the platelet surface binding of each of these monoclonal antibodies. Immunofluorescence microscopy demonstrated an internal pool of GPIV that, after thrombin stimulation, redistributed to the platelet surface. In a whole-blood flow-cytometric assay, alpha-thrombin and the thromboxane A2 analogue U46619 each resulted in an approximately twofold increase in the platelet surface binding of OKM5, whereas ADP had a more modest effect, and collagen and epinephrine had little effect. The activation-induced up-regulation of the platelet OKM5 epitope occurred in vivo as demonstrated by flow cytometric analysis of whole blood emerging from a standardized skin puncture site. In summary, both in vitro and in vivo platelet activation results in increased platelet surface expression of GPIV, as a result of a redistribution of GPIV from an internal pool.
Human leukemia inhibitory factor inhibits development of experimental atherosclerosis.
Authors: Moran C S , Campbell J H , Simmons D L , Campbell G R
Published: June 2011

The effect of human leukemia inhibitory factor (hLIF) on the development of atherosclerosis was investigated in an experimental animal model. Two conditions were examined: one in which lesions could arise because of the influence of both "injury" (cuffed vessel) and diet and one in which only the effect of diet could be significant in other areas of the vasculature (aorta). At time zero, the right carotid artery of rabbits (n = 32) was ensheathed in a soft Silastic cuff, and an osmotic minipump (2-mL capacity; 2.5 microL/h; 28 days) containing either hLIF or saline was inserted into the peritoneal cavity. Rabbits were divided into four groups (n = 8): group 1 received normal diet/saline; group 2, normal diet/LIF (30 micrograms.kg-1.d-1); group 3, 1% cholesterol diet/saline; and group 4, 1% cholesterol diet/LIF (30 micrograms.kg-1.d-1). After 28 days, the cholesterol diet (group 3) resulted in a sixfold increase in plasma cholesterol level compared with group 1 rabbits on a normal diet (3.80 +/- 0.50 versus 0.55 +/- 0.01 mmol/L). This was significantly lower (P = .01) with hLIF treatment in group 4 rabbits (2.80 +/- 0.44 mmol/L). Group 2 rabbits had higher aortic tissue cholesterol levels (1.40 +/- 0.35 mg/g) compared with group 1 rabbits on a normal diet (0.10 +/- 0.06 mg/g) (P = .01), whereas hLIF treatment decreased tissue cholesterol levels by 60% in group 4 rabbits (0.60 +/- 0.05 mg/g) (P = .01). Group 3 rabbits developed lipid-filled lesions covering 63.25 +/- 17.66% of the thoracic aorta surface, whereas lesions were significantly reduced (9.88 +/- 8.79%) (P = .01) with LIF treatment (group 4).(ABSTRACT TRUNCATED AT 250 WORDS)
Polymorphonuclear leukocyte-induced vasocontraction and endothelial dysfunction. Role of selectins.
Authors: Murohara T , Buerke M , Lefer A M
Published: June 2011

The roles of selectin adhesion molecules (P- and L-selectin) and their counterreceptor sialyl Lewisx were investigated in polymorphonuclear leukocyte (PMN)-induced cat coronary vasocontraction and endothelial dysfunction. Unstimulated autologous PMNs (10(6) cells/mL) were added to organ chambers containing cat coronary artery rings stimulated with either thrombin (2 U/mL) or hydrogen peroxide (100 mumol/L). PMNs elicited a significant vasocontraction in thrombin- (119 +/- 14 mg) and hydrogen peroxide- (132 +/- 15 mg) stimulated coronary rings. This PMN-induced vasocontraction was significantly attenuated by pretreatment with either an anti-P-selectin, an anti-L-selectin monoclonal antibody (ie, MAb PB 1.3 and MAb DREG-200), or a sialyl Lewis(x)-containing oligosaccharide (SLe(x)-OS). Endothelial function as assessed by endothelium-dependent vasorelaxation to acetylcholine was also significantly attenuated after PMN-induced vasocontraction in stimulated coronary rings. This endothelial dysfunction was significantly prevented by either PB 1.3, DREG-200, or SLe(x)-OS. In contrast, endothelium-independent relaxation to acidified sodium nitrite was not altered by PMN incubation, indicating that vascular smooth muscle function was unaffected. Adherence of PMNs to coronary endothelium also significantly increased following stimulation of endothelium with either thrombin or hydrogen peroxide, but this was significantly attenuated by PB 1.3, DREG-200, or SLe(x)-OS. Thus, PMN-endothelial interaction mediated by either selectin adhesion molecules (ie, P-selectin and L-selectin) or sialyl Lewis(x) may play an important role in PMN-induced vasocontraction and endothelial dysfunction. This mechanism may be important in the early endothelial dysfunction observed following reperfusion of an ischemic coronary vasculature.
Procoagulant Human Monocytes Mediate Tissue Factor/Factor VIIa–Dependent Platelet-Thrombus Formation When Exposed to Flowing Nonanticoagulated Human Blood
Authors: Barstad R. Marius , Hamers Maria J. A. G. , Kierulf Peter , Westvik Åse-Britt , Sakariassen Kjell S.
Published: June 2011

Abstract
Tissue factor (TF) on monocyte and macrophage surfaces is a nonproteolytic cofactor for factor VIIa (FVIIa)–induced coagulation. Monocyte-derived macrophages in atherosclerotic plaques express TF, which, after plaque disruption or rupture, may complex with FVII/VIIa from the bloodstream, resulting in activation of extrinsic coagulation. We studied the effect of TF expression on human monocytes on arterial thrombus formation in a model system of thrombogenesis. Thawed, cryopreserved human monocytes adherent to plastic coverslips were stimulated with lipopolysaccharide (0.5 μg/mL) to express TF and subsequently exposed to flowing nonanticoagulated human blood in a parallel-plate perfusion chamber. The wall shear rate at the cell surface was 650 seconds
−1
, corresponding to that of average-sized coronary arteries. The stimulated monocytes elicited pronounced fibrin deposition and platelet-thrombus formation. The platelet-thrombus volume was as large as that triggered by human type III collagen fibrils under similar experimental conditions. In contrast, the monocytes elicited much more fibrin deposition than the collagen surface. However, inclusion of an anti-TF monoclonal antibody that blocks the complexation of FVII/FVIIa with TF virtually abolished the fibrin deposition (
P
<.03) and reduced platelet-thrombus formation by more than 70% (
P
<.04). Thus, arterial thrombus formation induced by stimulated monocytes was almost completely blocked by the anti-TF antibody, suggesting that inhibition of TF/FVIIa complex formation on monocytes and macrophages at sites of plaque rupture or after percutaneous transluminal coronary angioplasty procedures may reduce intravascular thrombotic complications.
C/T Polymorphism in the 5′ Untranslated Region of the Apolipoprotein(a) Gene Introduces an Upstream ATG and Reduces In Vitro Translation
Authors: Zysow Bernice R. , Lindahl Gisela E. , Wade David P. , Knight Brian L. , Lawn Richard M.
Published: June 2011

Abstract
Elevated plasma levels of lipoproteinz(a) [Lp(a)] are a significant independent risk factor for arteriosclerosis. Interindividual levels of Lp(a) vary nearly 1000-fold and are mainly due to inheritance that is linked to the locus of the apolipoprotein(a) [apo(a)] gene. A search was made for sequence variants in the 5′ flanking region of the apo(a) gene that affect its expression. A C to T transition at position +93 from the transcription start site was found with a frequency of 14% in the study population. In transient transfection assays in HepG2 cells, luciferase reporter gene constructs with a T at this position were associated with a 58% reduction in luciferase activity compared with the more common allele. This single base variant had no significant effect on the binding of nuclear regulatory proteins; however, it introduced an additional upstream ATG initiation codon with its own in-frame stop codon. Furthermore, equivalent levels of mRNA were produced in HepG2 cells transfected with reporter gene constructs containing either a T or a C at position +93. In vitro translation experiments using transcripts derived from either variant apo(a) promoter revealed a 60% reduction in translation associated with the T allele. Hence, the additional ATG created by the T at position +93 in the 5′ flanking region of the apo(a) gene impairs the efficiency of translation from the bona fide ATG initiation codon.