bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro endothelial wound repair. Interaction of cell migration and proliferation.
Authors: Coomber B L , Gotlieb A I
Published: June 2011

Most re-endothelialization requires both cell migration and cell proliferation. To study the association between cell migration and the initiation of DNA synthesis in an in vitro wound model, confluent cultures of porcine aortic endothelial cells grown on glass coverslips were scraped to remove half of the monolayer. Treatment with 1 ng/ml of taxol, a microtubule stabilizing drug, for 24 hours resulted in no visible change in F-actin or microtubule organization as assessed by fluorescence and immunofluorescence microscopy. There was, however, a reduction of wound re-endothelialization and an associated reduction in the proportion of cells with centrosomes redistributed toward the wound edge. No significant differences, however, were seen in the labeling indices for the first two rows of cells at the wound edge as revealed by 3H-thymidine autoradiography. Labeling of nuclei in Rows 3 to 8 and in a zone deeper within the monolayer was reduced in treated cultures. The data suggest that endothelial proliferation in cells within an area bordering a wound is dependent on both denudation, which is sufficient to promote maximal proliferation in the two rows adjacent to the wound, and cell migration, which is required for the propagation of proliferation in cells further away from the wound edge.
Insulin resistance is associated with lipid and lipoprotein abnormalities in subjects with varying degrees of glucose tolerance.
Authors: Laakso M , Sarlund H , Mykkänen L
Published: June 2011

We tested the hypothesis that insulin resistance, rather than high insulin level, is associated with lipid and lipoprotein changes favoring atherosclerosis independently of the glucose tolerance status. To this aim, 50 subjects with normal glucose tolerance, 28 subjects with impaired glucose tolerance, and 54 subjects with noninsulin-dependent diabetes (NIDDM) were studied. Subjects with low glucose disposal rate (GDR) or a high degree of insulin resistance as measured by the euglycemic hyperinsulinemic clamp technique had lower high density lipoprotein (HDL) cholesterol and higher total and very low density lipoprotein (VLDL) triglycerides than did subjects with high GDR (highest GDR tertile). These associations were independent of fasting insulin level and other confounding factors. In stepwise multiple linear regression analysis, GDR was the most important single variable associated with HDL cholesterol and VLDL triglyceride level independently of age, obesity, distribution of obesity (waist/hip ratio), 2-hour glucose level, and free fatty acid concentration. We conclude: 1) insulin resistance measured by the euglycemic clamp technique is associated with adverse lipid and lipoprotein changes favoring atherosclerosis not only in nondiabetic subjects (as shown in previous studies) but also in impaired glucose tolerance and NIDDM subjects; 2) the association of high insulin level with adverse lipid and lipoprotein changes indirectly reflects the association of insulin resistance with lipid and lipoprotein levels; and 3) HDL cholesterol and VLDL triglycerides are independently associated with insulin-mediated glucose uptake, which may indicate that these lipoproteins have separate sites of interaction with insulin action.
Lipoprotein(a), fibrin binding, and plasminogen activation.
Authors: Loscalzo J , Weinfeld M , Fless G M , Scanu A M
Published: June 2011

Lipoprotein(a) (Lp[a]) is a complex plasma lipoprotein in which apolipoprotein (apo) B-100 is covalently linked by a disulfide bridge to a unique apolipoprotein, apo(a). The cDNA of apo(a) has recently been isolated and sequenced, and a remarkable homology to human plasminogen has been noted. In this report, we demonstrate that, like plasminogen, Lp(a) binds to fibrin. In addition, Lp(a) competes with plasminogen and tissue-type plasminogen activator for fibrin binding. As a functional consequence of these binding properties, we show that Lp(a) attenuates the fibrin-dependent enhancement of tissue-type plasminogen activator activity against the native substrate, and does so as an uncompetitive inhibitor (Ki = 15 nM). Finally, we show that in a plasma milieu, Lp(a) attenuates clot lysis induced by tissue-type plasminogen activator. None of these effects was noted with low density lipoprotein free of apo(a). These data suggest that Lp(a) influences the fibrinolytic system and probably does so by virtue of the fibrin binding properties conferred by the kringle repeats of apo(a).
Collagen type III induced ex vivo thrombogenesis in humans. Role of platelets and leukocytes in deposition of fibrin.
Authors: Sakariassen K S , Joss R , Muggli R , Kuhn H , Tschopp T B , Sage H , Baumgartner H R
Published: June 2011

Exposure of type III collagen coats on plastic cover slips in parallel-plate perfusion chambers to flowing nonanticoagulated human blood resulted in deposition of platelets and fibrin. Blood was drawn directly from an antecubital vein by an occlusive roller pump over the collagen coats in chambers having flow slits of different dimensions, so that wall shear rates of 100, 650, and 2600 s-1 were obtained at 10 ml/min. Coagulation was minimally activated during the passage of blood from the vein to the chamber as shown by fibrinopeptide A levels of 3.7 ng/ml after 5-minute perfusions. The surface coverage with platelets increased from 18% at 100 s-1 to 59% at 2600 s-1, and the corresponding thrombus volumes increased from 2 to 22 microns 3/microns 2, respectively. This contrasted with the coverage with fibrin on collagen, which decreased from 28% at 100 s-1 to 9% at 2600 s-1. Fibrin deposits on the thrombi covered 6% of the surface irrespective of the shear rate, indicating that some of the deposited platelets accelerated the deposition of fibrin. The type III collagen preparation did not activate factor XII and did not possess tissue factor activity, indicating that the surface itself was not procoagulant. However, a correlation between deposited leukocytes and surface coverage with fibrin was observed (r = 0.78, p less than 0.01), suggesting a role for these cells in the deposition of fibrin. The data demonstrate that thrombogenesis is triggered by pure type III collagen, although the deposition of fibrin is not initiated by the collagen itself but presumably by deposited leukocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
Proliferation of smooth muscle cells at sites distant from vascular injury.
Authors: Reidy M A
Published: June 2011

This study investigated the phenomenon that injury at one specific site in blood vessels induces cell replication at distant vascular sites. A polyethylene tube was inserted via the common carotid into rat aortic arch, which caused focal endothelial cell loss and formation of platelet thrombi. In a similar fashion, a polyethylene tube was placed into the lower abdominal aorta via a femoral artery. All animals received 3H-thymidine continuously for 2 weeks, after which time segments of the aorta distant from the polyethylene tubing were processed for autoradiography. These sites showed no loss of endothelium or adherent platelets, and yet the smooth muscle and endothelial cell replications were significantly elevated as compared to control aortas. There was no significant change in blood pressure during these experiments and no increase in smooth muscle cell ploidy. When the polyethylene tubing was left in situ for 2 months, no increased replication of the smooth muscle cells was observed during the last 2 weeks of the experiment, and at this time the aorta adjacent to the tubing was completely re-endothelialized. Finally, the mitogenic activity of plasma from these animals was tested in vitro. At the time of a significant increase of in vivo cell replication (2 weeks), the mitogenic activity of the plasma from animals with the indwelling tubing was similar to that of the control animals. In summary, these data show that injury at one discrete arterial site leads to general cell proliferation in the same vessel, and the data would support the possibility that cell communication initiates this response.
Antisera and monoclonal antibodies specific for epitopes generated during oxidative modification of low density lipoprotein.
Authors: Palinski W , Ylä-Herttuala S , Rosenfeld M E , Butler S W , Socher S A , Parthasarathy S , Curtiss L K , Witztum J L
Published: June 2011

Increasing evidence indicates that low density lipoprotein (LDL) has to be modified to induce foam cell formation. One such modification, oxidation of LDL, generates a number of highly reactive short chain-length aldehydic fragments of oxidized fatty acids capable of conjugating with lysine residues of apoprotein B. By immunizing animals with homologous malondialdehyde-modified LDL (MDA-LDL), 4-hydroxynonenal-LDL (4-HNE-LDL), and Cu+(+)-oxidized LDL, we developed polyvalent and monoclonal antibodies against three epitopes found in oxidatively modified LDL. The present article characterizes an antiserum and monoclonal antibody (MAL-2 and MDA2, respectively) specific for MDA-lysine, and an antiserum and monoclonal antibody (HNE-6 and NA59, respectively) specific for 4-HNE-lysine. In addition, a monoclonal antibody (OLF4-3C10) was developed against an as yet undefined epitope generated during Cu++ oxidation of LDL. With these antibodies, we demonstrated that MDA-lysine and 4-HNE-lysine adducts develop on apo-lipoprotein B during copper-induced oxidation of LDL in vitro. The application of these antibodies for immunocytochemical demonstration of oxidized lipoproteins in atherosclerotic lesions of progressive severity is described in the companion article. These antibodies should prove useful in studying the role of oxidatively modified lipoproteins as well as other oxidatively modified proteins in atherogenesis.
Distribution of oxidation specific lipid-protein adducts and apolipoprotein B in atherosclerotic lesions of varying severity from WHHL rabbits.
Authors: Rosenfeld M E , Palinski W , Ylä-Herttuala S , Butler S , Witztum J L
Published: June 2011

Antisera and monoclonal antibodies generated against autologous malondialdehyde-conjugated low density lipoprotein (MDA-LDL), 4-hydroxynonenal conjugated LDL (4-HNE-LDL), and the protein fragments of apoprotein B resulting from the copper oxidation of LDL, as well as antibodies against apoprotein B, were used to immunostain atherosclerotic lesions of varying severity from Watanabe heritable hyperlipemic rabbits. In macrophage-rich fatty streaks and transitional lesions, all of the antibodies recognizing oxidation specific epitopes exhibited predominantly cell-associated staining in particulate and annular patterns. This is in contrast to the limited, extracellular, diffuse staining obtained with the antibodies recognizing apoprotein B. In more advanced lesions containing areas with reduced numbers of cells, there was increased extracellular, diffuse staining with the antibodies against oxidation specific epitopes and co-localization with apoprotein B. In addition, there were annular staining patterns associated with the necrotic core and increased staining of intimal and medial smooth muscle cells. We interpret these data as suggesting that in areas of lesions rich in macrophages, LDL is oxidized and taken up by the cells. In more advanced lesions that are relatively devoid of macrophages, both native and oxidized LDL, as well as oxidation products released from dead and decaying cells, are trapped in the matrix, out of reach of those cells capable of accumulating oxidized LDL.
Inhibition of thrombus formation in vivo by novel antiplatelet agent.
Authors: Marzec U M , Kelly A B , Hanson S R , Lasslo A , Harker L A
Published: June 2011

The antithrombotic and antihemostatic effects of the novel antiplatelet compound, alpha, alpha'-bis[3-(N,N-diethylcarbamoyl)piperidino]-p-xylene dihydrobromide (GT-12), were investigated in a baboon model of platelet-dependent thrombosis under high flow conditions. In this model, segments of collagen-coated tubing and Dacron vascular graft were placed as thrombus-inducing extension devices in exteriorized femoral arteriovenous shunts. The deposition of 111In-labeled platelets was measured for each thrombogenic segment throughout 1 hour by using gamma camera imaging. In addition, the 125I-fibrin retained in the forming thrombus was measured. Intravenous infusion of GT-12 (100 mumol/kg, 63.3 mg/kg) over a 15-minute period before the insertion of the test segments prolonged the bleeding time from a baseline value of 4.4 +/- 0.4 min to 7.6 +/- 1.0 min (p = 0.036) and inhibited platelet aggregation ex vivo induced by adenosine diphosphate (ED50 4.7 +/- 0.9 to 10.3 +/- 2.2 microM; p less than 0.02) and collagen (ED50 2.0 +/- 0.4 to 8.0 +/- 2.4 micrograms/ml; p less than 0.05). Deposition of platelets and fibrin was decreased in concert by 30% (p less than 0.05) for vascular grafts and possibly collagen segments at the end of the 60-minute observation period. We conclude that GT-12 is antithrombotic for Dacron graft-induced thrombus formation in vivo.
Thrombogenicity of vascular cells. Comparison between endothelial cells isolated from different sources and smooth muscle cells and fibroblasts.
Authors: Zwaginga J J , de Boer H C , IJsseldijk M J , Kerkhof A , Muller-Berghaus G , Gruhlichhenn J , Sixma J J , de Groot P G
Published: June 2011

When the endothelial cell layer is damaged, a thrombotic reaction starts on the cells' subendothelium and on the connective tissue deposited by smooth muscle cells in the deeper layers. When more severe vascular damage occurs, hemostasis will involve the vessel adventitia in which fibroblasts are found. In this article, the influence of in vitro cultured endothelial cells, smooth muscle cells, and fibroblasts on the hemostatic balance was studied. To do so, perfusions were performed with low molecular weight heparin anticoagulated blood over the extracellular matrix of the cells. This method allowed the study of tissue factor-dependent thrombin generation and its influence on formation of fibrin and platelet aggregates. The experiments described in this article show that endothelial cells isolated from different human organs interfere differently in the hemostatic response. Endothelial cells isolated from umbilical veins are nonthrombogenic; they do not synthesize tissue factor under unstimulated conditions. On their extracellular matrix, only adherent platelets are found, but no aggregates and no fibrin. Endothelial cells isolated from omentum and atrium contain tissue factor activity under unstimulated conditions. As a consequence, thrombin is generated on their surfaces, and platelet aggregates and fibrin deposition are found on the extracellular matrices after perfusions with whole blood. The matrix of smooth muscle cells and fibroblasts behaved similarly. Increase in shear rate and perfusion time resulted in an increase in platelet aggregate formation. Polymerized fibrin deposition decreased when perfusions were performed at higher shear. Both platelet aggregation and fibrin deposition were tissue factor dependent and could be blocked more than 70% by an antibody against tissue factor. Based on these results, we conclude that endothelial cells isolated from umbilical veins form the best nonthrombogenic surface in vitro. Moreover, coagulation-dependent hemostasis should be included when thrombogenicity of subendothelium is discussed, especially when it concerns matrix derived from cells present in the deeper layer of the vessel wall.
von Willebrand factor and occlusive arterial thrombosis. A study in normal and von Willebrand's disease pigs with diet-induced hypercholesterolemia and atherosclerosis.
Authors: Nichols T C , Bellinger D A , Tate D A , Reddick R L , Read M S , Koch G G , Brinkhous K M , Griggs T R
Published: June 2011

The thrombotic response of atherosclerotic arteries to stenosis and injury was studied in 14 pigs, eight normal and six with von Willebrand's disease (vWD). Atherosclerosis was produced by feeding a 1% to 2% cholesterol diet for 24 weeks. Both groups of pigs developed severe hypercholesterolemia, greater than five times baseline values. Coronary atherosclerosis was detected in all vWD pigs and in all but one normal pig and was not significantly different between groups. At sacrifice under general anesthesia, a Goldblatt clamp (GC) was positioned around the left anterior descending coronary (LAD) and carotid arteries to produce a stenotic segment, which was pinch-injured with needle holders. A 20 MHz Doppler velocity crystal was placed distal to the GC to detect cyclic flow reductions or permanent cessation of flow velocity indicative of occlusive thrombosis. In the phenotypically normal pigs with diet-induced atherosclerosis, occlusive thrombosis was detected in seven of seven LAD and seven of seven carotid arteries. In atherosclerotic vWD pigs, occlusive thrombosis failed to form in six LAD and 10 carotid arteries (p less than 0.003, Wilcoxon rank sum test). Scanning electron micrographs demonstrated platelet-fibrin microthrombi in both groups of pigs; only phenotypically normal pigs had occlusive thrombi. Von Willebrand factor is essential for the development of occlusive thrombosis and appears to support the progression of a mixed microthrombus to an occlusive thrombus.
Ischemic heart disease risk in postmenopausal women. Effects of estrogen use on glucose and insulin levels.
Authors: Barrett-Connor E , Laakso M
Published: June 2011

We report the fasting and post-challenge plasma insulin and glucose levels in 469 nondiabetic postmenopausal women from the Rancho Bernardo cohort according to the current use of estrogen replacement therapy. In these older women, the use of noncontraceptive estrogen was not associated with impaired glucose tolerance. Estrogen-treated women had lower levels of insulin than women who were not taking estrogen; these differences were not explained by age, obesity, or differential hormone use by women with known glucose intolerance. There were no significant differences in glucose and insulin levels in those taking conjugated equine estrogen (Premarin) alone compared to those taking it with medroxyprogesterone acetate (Provera).
Secular trends in atherosclerosis of coronary arteries and basal cerebral arteries in Japan. The Akita pathology study.
Authors: Konishi M , Komachi Y , Iso H , Iida M , Naito Y , Sato S , Kiyama M , Shimamoto T , Kitamura A , Doi M
Published: June 2011

The atherosclerotic lesions of the coronary arteries and basal cerebral arteries in the circle of Willis were examined in the bodies of decreased men ages 30 and over who had been admitted to a local hospital in northeast Japan during 1966 to 1974 (243 men) and 1975 to 1984 (602 men). The autopsy rates during the two periods were 86% and 89%, respectively. The extent of atherosclerosis was determined blindly by one pathologist using a grading method of cross-sectional stenosis scoring for coronary arteries and Baker's method for basal cerebral arteries. The age-adjusted mean scores for atherosclerosis in the coronary arteries and basal cerebral arteries were 30% and 42% lower, respectively, in the 1975 to 1984 period than in the 1966 to 1974 period (p less than 0.001). There was also a fall in age-adjusted blood pressure levels at admission: 10 mm Hg for systolic and 4 mm Hg for diastolic blood pressure (p less than 0.001). The opposite trend was seen in mean serum cholesterol: a rise from 171 mg/dl to 177 mg/dl (p = 0.018). Linear regression analysis indicated that blood pressure was positively associated with both atherosclerosis scores, controlling for age and serum cholesterol in both time periods (p less than 0.001). The association of serum cholesterol with the atherosclerosis scores was positive in both periods and statistically significant in 1975 to 1984. Similar findings were obtained when the analyses were conducted for cardiovascular disease (myocardial infarction and stroke) and for noncardiovascular disease, separately.(ABSTRACT TRUNCATED AT 250 WORDS)
Retroendocytosis of high density lipoproteins by the human hepatoma cell line, HepG2.
Authors: Kambouris A M , Roach P D , Calvert G D , Nestel P J
Published: June 2011

When human HepG2 hepatoma cells were pulsed with 125I-labeled high density lipoproteins (HDL) and chased in fresh medium, up to 65% of the radioactivity released was precipitable with trichloroacetic acid. Cell-internalized 125I-HDL contributed to the release of acid-precipitable material; when cells were treated with trypsin before the chase to remove 125I-HDL bound to the outer cell membrane, 50% of the released material was still acid-precipitable. Characterization of the radioactive material resecreted by trypsinized cells revealed the presence of particles that were similar in size and density to mature HDL and contained intact apolipoproteins (apo) A-I and A-II. The release of internalized label occurred at 37 degrees C but not at 4 degrees C. Monensin, which inhibits endosomal recycling of receptors, decreased the binding of 125I-HDL to cells by 75%, inhibited the release of internalized radioactivity as acid-precipitable material by 80%, and increased the release of acid-soluble material by 90%. In contrast, the lysosomal inhibitor chloroquine increased the association of 125I-HDL to cells by 25%, inhibited the release of precipitable material by 10%, and inhibited the release of acid-soluble radioactivity by 80%. Pre-incubation with cholesterol caused a 50% increase in the specific binding, internalization, and resecretion of HDL label. Cholesterol affected the release of acid-precipitable label much more (+90%) than that of acid-soluble material (+20%). Taken together, these findings suggest that HepG2 cells can bind, internalize, and resecrete HDL by a retroendocytotic process. Furthermore, the results with cholesterol and monensin indicate that a regulated, recycling, receptor-like molecule is involved in the binding and intracellular routing of HDL.
Effect of fish oil on atherogenesis in Watanabe heritable hyperlipidemic rabbit.
Authors: Lichtenstein A H , Chobanian A V
Published: June 2011

The effect of dietary supplementation with fish oil was investigated in the Watanabe heritable hyperlipidemic (WHHL) rabbit. Rabbits were fed Maxepa (1 g/kg body weight) from weaning for a 6-month period and were compared to controls. Fish oil supplements resulted in significant decreases in plasma triglyceride and cholesterol at 4 weeks after the start of the study, and these differences persisted over the 6-month period. No differences in the distribution of cholesterol or triglyceride among lipoprotein particles were found, nor were there differences in low density lipoprotein particle size. The decreases in plasma cholesterol and triglyceride were accompanied by significant increases in the percent of eicosapentaenoic and docosahexaenoic acids in both plasma and platelets. Fish oil supplementation resulted in a decrease in platelet count and response to the aggregating agents adenosine diphosphate, arachidonic acid, and collagen. Systolic blood pressure was significantly lower in the rabbits fed fish oil. At the end of the study period, aortic free and esterified cholesterol and intimal surface area covered with plaque were determined in the arch and in the descending and abdominal aorta. Significantly less cholesterol was found in the descending and abdominal aorta. These differences were mirrored by decreased activities of acid lipase and N-acetyl-beta-glucosaminidase. In contrast, no differences in the intimal surface area covered with plaque were found. In conclusion, dietary fish oil resulted in a decrease in aortic lipid deposition in the WHHL rabbit, which may have been due to decreases in plasma triglyceride and cholesterol, platelet count and aggregability, and systolic blood pressure.
Dose- and shear rate-dependent effects of heparin on thrombogenesis induced by rabbit aorta subendothelium exposed to flowing human blood.
Authors: Inauen W , Baumgartner H R , Bombeli T , Haeberli A , Straub P W
Published: June 2011

The effect of heparin on thrombogenesis induced by the subendothelium of rabbit aorta was investigated in 24 healthy volunteers after intravenous injection of different doses (0, 1000, 2500, and 5000 IU). By using an ex vivo perfusion chamber system, the interaction between flowing blood and exposed subendothelium was measured at low (50 s-1), intermediate (650 s-1), and high (2600 s-1) wall shear rates. The low shear rate simulated blood flow in venous, the intermediate shear rate in arterial, and the high shear rate in small or stenosed arterial vessels. Deposition of fibrin, platelets, and platelet thrombi on vascular subendothelium (SE) was quantified by morphometrical and immunological techniques. Fibrin deposition prevailed at low shear rates and was only minimal at high shear rates (30 +/- 1% vs. 1 +/- 0.4% coverage of SE with fibrin, means +/- SEM, p less than 0.001). In contrast, the interaction of platelets with SE was more intense at high compared to low shear rates, as indicated by higher platelet adhesion (54 +/- 5% vs. 4 +/- 1% coverage of SE with platelets, p less than 0.001) and platelet thrombus volumes (4.8 +/- 1.3 vs. 0.5 +/- 0.1 microns 3/microns 2, p less than 0.001). Fibrin deposition on SE was inhibited by heparin in a dose-dependent manner and was abolished after high doses. In addition, high doses of heparin reduced the height and volume of platelet thrombi at low and intermediate wall shear rates, but no effect was found at the high shear rate. Our data show that heparin inhibits the formation of both fibrin and platelet thrombi on vascular subendothelium. The lack of effect of heparin on platelet thrombus formation at high shear rates indicates that thrombin modulates the growth rate and/or stability of platelet thrombi at low and intermediate shear rates, whereas additional factors may control platelet thrombus growth and stability at high shear conditions.
Differential effect of Photofrin II on growth of human smooth muscle cells from nonatherosclerotic arteries and atheromatous plaques in vitro.
Authors: Dartsch P C , Ischinger T , Betz E
Published: June 2011

The effect of dihematoporphyrin-ester or -ether (DHE), a photosensitizing porphyrin with different amounts of aggregates, on the growth of cultured smooth muscle cells obtained from nonatherosclerotic arteries and from atheromatous plaques (primary stenosing and restenosing lesions) was examined without photoactivation of the drug. Clinically relevant DHE concentrations ranging from 0.1 to 25 micrograms/ml were used. In all proliferation studies with cells of second and third passage (approximately 10 cumulative population doublings in vitro), the growth rates decreased in a dose-dependent manner. Smooth muscle cells from atherosclerotic lesions were significantly more sensitive than smooth muscle cells from normal arteries. Cells derived from restenosing lesions retained their increased sensitivity even after eight passages in culture (approximately 20 cumulative population doublings). Cell size measurements showed that the decreased proliferative activity mainly occurred in smooth muscle cell subpopulations consisting of small cells. A cytotoxic effect of DHE was observed at concentrations above 5 micrograms/ml, causing cytoplasmic protrusions, vacuoles, and even complete cell lysis. At a DHE concentration of 5 micrograms/ml, the number of viable cells was 73% +/- 14% (means +/- SD) for smooth muscle cells from nonatherosclerotic arterial media and only 38% +/- 11% (means +/- SD) for smooth muscle cells from atherosclerotic plaques. In all experiments, no significant difference in response to DHE treatment was observed between cells from primary stenosing and restenosing lesions, suggesting a specific mechanism for plaque-derived cells causing an increased sensitivity in comparison to smooth muscle cells from nonatherosclerotic arteries. The pronounced sensitivity of plaque cells against DHE treatment suggests that this drug--even without photoactivation--is potentially valuable in vivo as a therapeutic approach to vascular stenoses.
Role of dying endothelial cells in transendothelial macromolecular transport.
Authors: Lin S J , Jan K M , Chien S
Published: June 2011

There are focal areas in the aorta with an enhanced endothelial permeability to macromolecules, as indicated by the focal uptake of the protein-binding azo dye Evans blue in vivo. These areas exhibit high rates of endothelial cell turnover and a number of structural characteristics in en face endothelial morphology. To determine the relationship of endothelial cell death to macromolecular leakage at the level of individual endothelial cells, thoracic aortas of 12 adult male Sprague-Dawley rats were studied at 3 to 5 minutes after intravenous administration of Evans blue-albumin (EBA). Leakage of EBA around individual endothelial cells in en face preparations of the aorta was visualized by fluorescence microscopy. Dying or dead endothelial cells were identified by indirect immunoglobulin G (IgG) immunocytochemistry. Although endothelial cell death is uncommon in normal aortic endothedium (i.e., an average frequency of 0.48%), a high percentage (63%) of IgG-containing dying or dead endothelial cells was found to be associated with EBA leakage. These dying or dead endothelial cells were responsible for 37% of total EBA leaky foci. The results suggest that, in addition to mitotic endothelial cells, the dying or dead endothelial cells also make significant contributions to the local enhancement in aortic endothelial permeability. The present findings lend further support to the "cell turnover-leaky junction" hypothesis for the localization of atherosclerosis.
Noninvasive ultrasound evaluation of pressure gradients in aortic root of homozygotes for familial hypercholesterolemia.
Authors: Faccenda F , Rubba P , Gnasso A , Pauciullo P , Postiglione A , Cortese C , Mancini M
Published: June 2011

The aim of this study was to measure noninvasively by Doppler ultrasound the blood flow velocity at the level of the aortic root in patients with homozygous familial hypercholesterolemia (FH) to detect abnormal pressure gradients. Seven patients with homozygous FH and seven healthy controls matched for age and sex were included in the study. Continuous-wave Doppler (2 MHz) was used to measure the highest detectable velocity from the aortic root; the probe was positioned in the suprasternal notch. When an abnormal velocity was detected, the corresponding pressure drop was calculated from the formula: Delta P = 4Vmax2. Each FH patient had an abnormal aortic velocity consistent with a pressure gradient across the valvular area. All the controls had normal aortic velocities (p less than 0.01). The measurement of the pressure drop across the aortic valvular area in FH patients gives an estimate of the lesions produced by cholesterol deposition in a crucial area of the cardiovascular system near the origin of coronary arteries. The noninvasivity of this method makes it an excellent method for obtaining parameters for follow-up and clinical trials.
Microalbuminuria. Potential marker for increased cardiovascular risk factors in nondiabetic subjects?
Authors: Haffner S M , Stern M P , Gruber M K , Hazuda H P , Mitchell B D , Patterson J K
Published: June 2011

Microalbuminuria is associated with progression to renal disease in insulin-dependent diabetes and with increased mortality in noninsulin-dependent diabetes. In contrast, few studies have addressed the effect of microalbuminuria on cardiovascular risk in nondiabetics. We, therefore, determined the level of microalbuminuria in 316 nondiabetic subjects from the San Antonio Heart Study, a population-based study of diabetes and cardiovascular risk factors. Microalbuminuria (greater than or equal to 30 mg/l) was found in 42 of these 316 subjects (13%). Subjects with microalbuminuria had significantly higher blood pressure, triglyceride concentration, sum of insulin concentrations during a glucose tolerance test, and prevalence of hypertension and of self-reported myocardial infarction than subjects without microalbuminuria. When subjects with hypertension were excluded (n = 27), normotensive subjects with microalbuminuria (n = 31) still had significantly higher triglyceride concentrations and insulin sum than normotensive subjects without microalbuminuria (n = 258), suggesting that an increased atherogenic risk factor pattern exists even in normotensive subjects with microalbuminuria. Microalbuminuria may be a marker for cardiovascular risk, although it is not certain whether microalbuminuria causes these metabolic changes or results from some metabolic disturbance such as insulin resistance.
Secretion of plasminogen activator inhibitor-1 from cultured human umbilical vein endothelial cells is induced by very low density lipoprotein.
Authors: Stiko-Rahm A , Wiman B , Hamsten A , Nilsson J
Published: June 2011

Clinical studies have demonstrated an impaired fibrinolytic function in patients with angiographically ascertained coronary artery disease or previous myocardial infarction. This decreased fibrinolytic function is to a major extent explained by the presence of high plasma levels of plasminogen activator inhibitor-1 (PAI-1) and is most common in patients with hyperlipoproteinemias type IIB and IV. To further investigate the association between hypertriglyceridemia and elevated plasma levels of PAI-1, cultured human umbilical vein endothelial cells were exposed to purified lipoproteins isolated from normo- and hypertriglyceridemic (NTG and HTG) individuals. We found that very low density lipoprotein (VLDL) from both NTG and HTG subjects stimulated the secretion of PAI-1 from endothelial cells in a dose-dependent manner. HTG-VLDL at a concentration of 100 micrograms/ml gave rise to a 73% increase in PAI-1 secretion as compared to control cultures, whereas NTG-VLDL only gave rise to a 30% increase (p less than 0.05), indicating that HTG-VLDL is a more potent stimulus to PAI-1 secretion than is NTG-VLDL. Experiments in which endothelial cells were exposed to VLDL subfractions indicated that large VLDL particles, in particular, induce PAI-1 release. Binding experiments demonstrated a specific cellular binding of both NTG- and HTG-VLDL to the cells, but HTG-VLDL bound about four times more effectively than NTG-VLDL. Exposure of the endothelial cells to an LDL receptor antibody was found to block 75% (p less than 0.005) of the VLDL-induced secretion of PAI-1 from the cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Intimal lesion formation in rat carotid arteries after endothelial denudation in absence of medial injury.
Authors: Fingerle J , Au Y P , Clowes A W , Reidy M A
Published: June 2011

Injury of an artery by passage of a balloon catheter causes both endothelial denudation and medial damage and produces a marked smooth muscle cell (SMC) proliferative response. In this study, the endothelium from rat carotid arteries was removed by use of a rotating loop of 5/0 monofilament suture (gentle denudation technique), which did not cause any detectable damage to the underlying medial cells but did cause platelet adherence. Expression of platelet-derived growth factor (PDGF) A-chain and PDGF receptor mRNA was comparable to that seen in ballooned carotids, but the medial SMC proliferative response to gentle denudation was markedly reduced when compared to that observed after balloon denudation (1.4% vs. 13.6%). Intimal lesions were only observed in those zones that remained denuded for more than 7 days. These results demonstrate that a denuding injury with no medial trauma is sufficient to induce intimal lesions and that the significantly higher proliferation seen in ballooned vessels might reflect a response of the medial cells to trauma that occurred during denudation.
Relation of family history and reversible risk factors to coronary heart disease prevalence in an Afrikaner community.
Authors: Rossouw J E , Thompson M L , Jooste P L , Swanepoel A S , Jordaan P C
Published: June 2011

In a cross-sectional study of an Afrikaner community (n = 2,722 men and n = 3,173 women aged 25-64 years), family history of coronary heart disease (CHD) was associated with an adverse risk factor profile and with prevalent CHD. Men with myocardial infarction (MI) and a family history of CHD had higher total minus high density lipoprotein cholesterol (TC-HDLC) levels than men with MI but no CHD family history. In preliminary multiple regression analyses, family history of CHD appeared to exert its effect partly independently of known risk factors and partly dependently through age, TC minus HDLC, and HDLC. Even though their association with MI was weakened after entering family history into the models, the reversible risk factors (particularly TC minus HDLC, HDLC, and uric acid levels) continued to contribute to CHD. For MI in men, there was an interaction between family history of CHD and TC minus HDLC, to the extent that raised TC minus HDLC levels were adverse only in the presence of a positive CHD family history. The findings suggest coinheritance of high blood cholesterol and increased susceptibility to CHD. If confirmed in prospective studies, the interaction between family history and TC minus HDLC will have implications for cholesterol screening and management.
Treatment with hydroxymethylglutaryl-coenzyme A reductase inhibitors in hypercholesterolemia induces changes in the components of the extrinsic coagulation system.
Authors: Sandset P M , Lund H , Norseth J , Abildgaard U , Ose L
Published: June 2011

The present study was performed to determine the influence of pharmaceutical intervention on parameters of blood coagulation and fibrinolysis in hypercholesterolemic patients. Eighteen otherwise-healthy individuals with heterozygous familial hypercholesterolemia were treated with a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (simvastatin, 40 mg daily) for 12-14 weeks followed by additional treatment with omega-3 fatty acids (equivalent to 4 g eicosapentaenoic acid/docosahexaenoic acid daily) for 6 more weeks. With simvastatin treatment, the mean decreases in total cholesterol, low density lipoprotein (LDL) cholesterol, and apolipoprotein B (apo B) were 39%, 46%, and 36%, respectively. Only minor changes in high density lipoprotein (HDL) cholesterol and apo A-1 were recorded. omega-3 fatty acids had minor additional effects. The most prominent effects on the blood coagulation system were the changes in extrinsic pathway inhibitor (EPI), which is the inhibitor of the factor VIIa-tissue thromboplastin complex. EPI activity decreased from a median of 153% to 111% (p less than 0.001) with simvastatin treatment and to 112% (p less than 0.001) on the combined regimen. EPI activity was significantly correlated with LDL cholesterol (r = 0.78), total cholesterol (r = 0.77), apo B (r = 0.65), and apo A-1 (r = 0.45). Multiple stepwise regression analysis showed that LDL cholesterol was the most important predictor of EPI activity, which suggests that a majority of EPI activity in plasma is associated with LDL. Moreover, the alteration in EPI activity was correlated closely with the corresponding alteration in LDL, which suggests a direct relation between a coagulation-inhibitor activity and a pharmaceutical lipid-related response.(ABSTRACT TRUNCATED AT 250 WORDS)
Comparison of early microcirculatory and aortic changes in hypercholesterolemic rats.
Authors: Schuschke D A , Joshua I G , Miller F N
Published: June 2011

The microcirculatory changes caused by hypercholesterolemia were studied in the rat cremaster muscle model by intravital microscopy and were compared with aortic ring segments from the same animals. Male Sprague-Dawley rats were fed either a normal chow diet or a chow diet supplemented with 1% cholesterol and 0.5% cholic acid for 3 or 5 weeks before experimentation. Three weeks of hypercholesterolemia produced a significantly decreased vasodilator response to serotonin in the arterioles. This response was also seen after 5 weeks on the hypercholesterolemia diet. Three weeks of hypercholesterolemia produced a significantly increased macromolecular leakage from postcapillary venules in response to serotonin. However, after 5 weeks of hypercholesterolemia, the serotonin-induced leakage was less than in control animals. Hypercholesterolemia for 3 weeks decreased the arteriolar dilation evoked by acetylcholine but did not change the arteriolar response to sodium nitroprusside. Contraction of the aortic rings induced by serotonin and aortic ring relaxation induced by sodium nitroprusside were not different between 3-week-control and 3-week-hypercholesterolemic animals. However, 3 weeks of hypercholesterolemia attenuated the aortic ring relaxation evoked by acetylcholine. These results suggest that hypercholesterolemia causes an early depression of endothelium-derived relaxing factor (EDRF)-mediated receptor responses in both microvessels and the aorta, whereas non-EDRF-mediated receptor responses are altered in the microcirculation but not in the aorta.
Effects of native and oxidized low density lipoproteins on formation and inactivation of endothelium-derived relaxing factor.
Authors: Galle J , Mülsch A , Busse R , Bassenge E
Published: June 2011

The influence of native (N-) and oxidized (Ox-) low density lipoproteins (LDLs) on endothelium-dependent vasomotion is still controversial. We investigated the short-term effects of N-LDL and Ox-LDL on the formation of endothelium-derived relaxing factor (EDRF) in native and cultured endothelial cells and on its inactivation after release from the cells. N-LDL was isolated from fresh human plasma via sequential ultracentrifugation and oxidized by incubation with Cu2+. EDRF released from cultured endothelial cells was inactivated by both N-LDL and Ox-LDL (1 mg/ml) as detected in a bioassay system. N-LDL reduced the EDRF-mediated vasodilations of the detector segments by 38.5 +/- 5.3%, and Ox-LDL, by 55.5 +/- 4.6%. The effects of lipoproteins on EDRF formation were studied in cultured endothelial cells preincubated with either N-LDL or Ox-LDL (1 mg/ml for 1 hour) and stimulated for EDRF release with bradykinin after washout of the lipoproteins. EDRF was assessed by measuring its stimulatory effect on the activity of a purified, soluble guanylate cyclase. Both N-LDL and Ox-LDL did not reduce the bradykinin-induced EDRF formation. Consistent with this finding, acetylcholine-induced, EDRF-mediated dilations of intact rabbit femoral artery segments were not impaired by luminal exposure to N-LDL or Ox-LDL (1 mg/ml for 1 hour). However, these relaxations were significantly reduced by preincubation of aortic ring preparations with the same concentrations of the same charges of N-LDL and Ox-LDL. In conclusion, neither N-LDL nor Ox-LDL acutely impairs the formation of EDRF but does inactivate EDRF after its release from endothelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Plasma triglyceride and coronary heart disease.
Authors: Austin M A
Published: June 2011

Although the literature on epidemiological associations between plasma triglyceride and CHD is not completely consistent, trends do emerge from the studies described here. First, the majority of observational studies demonstrate a significant univariate relation, although the results of case-control and cross-sectional studies are more uniform than those from prospective study designs. In many but not all studies, triglyceride remains a significant predictor of CHD in multivariate statistical analyses after controlling for TC or LDL-C. Perhaps the least consistent result is that the triglyceride association does not persist in some analyses controlling for HDL-C, while in other studies, the association remains significant. Although most studies have been conducted in men, the studies providing data on women, normocholesterolemic subjects, and diabetic subjects have generally found triglyceride to be, at the very least, a univariate risk factor. The results of intervention trials differ considerably, but no such study to date has been specifically designed to evaluate triglyceride-lowering effects on primary prevention of CHD. Important statistical properties must be taken into consideration in evaluating triglyceride as a risk factor for CHD. The large variability of triglyceride measurements and the correlation of triglyceride values with other lipid measures appears to result in the underestimation of the association between triglyceride and disease in multivariate analyses. Finally, individual genetic susceptibility may play an important role in the relation between plasma triglyceride levels and CHD. For example, risk of CHD clearly varies among the well-established familial forms of hypertriglyceridemia. A predominance of small, dense, LDL particles (LDL subclass pattern B) also appears to be a genetic trait associated with both increased risk of MI and increases in plasma triglyceride levels.
Lipoprotein(a) in diet-induced atherosclerosis in nonhuman primates.
Authors: Nachman R L , Gavish D , Azrolan N , Clarkson T B
Published: June 2011

Lipoprotein(a) (Lp[a]) is a low density lipoprotein particle that contains plasminogen-like apolipoprotein(a). Recent studies suggest an association of Lp(a) with atherosclerotic vascular disease. We have studied the accumulation of Lp(a) in atherosclerotic arteries of monkeys with diet-induced atherosclerosis. Immunohistochemistry with monospecific Lp(a) antisera revealed striking accumulations of Lp(a) in atherosclerotic coronary artery lesions. There was no Lp(a) in the normal, nonatherosclerotic arteries. Analysis of paired tissue and serum samples from 17 male hyperlipoproteinemic monkeys revealed a significant correlation between aortic wall Lp(a) and serum Lp(a) levels. The serum cholesterol level failed to correlate with either aortic Lp(a) or serum Lp(a). These results add further evidence for the potential role of Lp(a) in the pathogenesis of atherosclerosis.
Detection of two species of low density lipoprotein particles in cholesteryl ester transfer protein deficiency.
Authors: Sakai N , Matsuzawa Y , Hirano K , Yamashita S , Nozaki S , Ueyama Y , Kubo M , Tarui S
Published: June 2011

By equilibrium density gradient ultracentrifugation, we analyzed the chemical composition and particle size of low density lipoproteins (LDLs) in 16 subfractions separated from the LDL fractions (1.019 less than d less than 1.063 g/ml) of two hyperalphalipoproteinemic patients who had a deficiency of cholesteryl ester transfer protein (CETP). The LDLs of these patients comprised a group of heterogeneous lipoprotein particles distributed almost equally in a wide density range from d = 1.025 g/ml to d = 1.053 g/ml, whereas LDLs from normal controls were a homogeneous group of lipoprotein particles distributed in a narrow density range from d = 1.030 g/ml to d = 1.046 g/ml. The LDL in each subfraction derived from the patients' plasma samples was poor in cholesteryl ester and rich in triglycerides and apolipoproteins. Each subfraction of normal control LDL contained only one species of homogeneous LDL particles, which progressively decreased in size with an increase in the density of the fraction. In contrast, each subfraction of patient LDL contained two species of LDL particles: smaller LDLs existed, in addition to those that were found to be identical to the normal control LDL particles observed in the corresponding subfractions. The intermediate density lipoproteins of the two patients were also composed of two species of lipoproteins. From these results, we speculate that two metabolic pathways may exist in the LDL formation process. In this process, the transfer of cholesteryl ester from high density lipoproteins by CETP may convert the smaller lipoprotein particles to the larger ones, forming the homogeneous LDL species.