bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxidation-Related Analytes and Lipid and Lipoprotein Concentrations in Healthy Subjects
Authors: Craig Wendy Y. , Poulin Sue E. , Palomaki Glenn E. , Neveux Louis M. , Ritchie Robert F. , Ledue Thomas B.
Published: June 2011

Abstract
The relations between oxidation-related analytes and lipoprotein risk factors for coronary heart disease are poorly understood. To address this issue, ceruloplasmin, copper, iron, ferritin, cotinine, lipid peroxides, cholesterol, triglyceride, apoB, apoA-I, and lipoprotein(a) levels were measured in sera from apparently healthy subjects (51 men and 115 women). Pairwise comparisons revealed strong positive associations (
P
<.001) of copper and ceruloplasmin with lipid peroxides, total cholesterol, triglycerides and apoB, of transferrin with apoA-I and cholesterol, and of ferritin with triglycerides. Serum levels of oxidation-related analytes did not differ between smokers and nonsmokers. In multivariate analysis, serum copper was the major independent determinant of serum lipid peroxide level, accounting for 15% of the variability in concentration (ferritin accounted for 1.6%). Copper and ceruloplasmin accounted for 20.5% of the variation in triglyceride levels; triglycerides and apoB accounted for 12% of the variability in ferritin levels; apoB and apoA-I accounted for 9% of the variability in transferrin levels. The data suggest that serum copper contributes to lipid peroxidation in vivo. There are significant associations between lipoprotein and transition metal-related analytes, and further work is needed to elucidate the physiological basis for these relations.
Inhibition of the Oxidative Modification of LDL by Nitecapone
Authors: Pentikäinen Markku O. , Lindstedt Ken A. , Kovanen Petri T.
Published: June 2011

AbstractWe studied in vitro the ability of nitecapone, 3-[(3,4-dihydroxy-5-nitrophenyl)methylene]-2,4-pentanedione, a novel water-soluble compound with antioxidative properties, to inhibit the LDL oxidation promoted by copper ions, the aqueous free radical generator 2,2′-azobis(2-amidinopropane) hydrochloride (AAPH), and mouse peritoneal macrophages. In these three oxidation systems, the extent of LDL oxidation was determined by measuring the formation of conjugated dienes, the formation of thiobarbituric acid–reactive substances, the change in the electrophoretic mobility of LDL, and the uptake of LDL by macrophages. When LDL oxidation was promoted by copper ions, the reaction was found to be inhibited by nitecapone added in a three- to five-molar excess of the concentration of copper ions. The mechanism by which nitecapone exerted its antioxidative effect in copper-mediated LDL oxidation depended on binding and redox inactivation of the copper ions. Moreover, nitecapone released LDL-bound copper ions and so rendered the LDL particles more resistant to oxidation. In contrast to a water-soluble α-tocopherol analogue that was rapidly consumed during the oxidative process, nitecapone retained its inhibitory effect for at least 2 days. Using immobilized metal ion affinity chromatography, we showed that nitecapone binds both copper and iron ions, whereas its affinity for zinc ions is low. Nitecapone also inhibited LDL oxidation in the free radical–mediated oxidation system (AAPH). In this system, nitecapone showed synergistic antioxidative action with ascorbic acid. Finally, nitecapone inhibited macrophage-mediated LDL oxidation. Accordingly, nitecapone appears to have a unique antioxidative profile in that it both selectively chelates pro-oxidative transition metals and scavenges free radicals. Moreover, nitecapone has the potential of protecting LDL from oxidation in more complex biological in vitro systems in which multiple modes of oxidative stress act simultaneously, suggesting that this new compound, already tested in humans for its ability to inhibit catechol-O-methyltransferase activity, could potentially be used as an antioxidant drug.
Platelet Cytosolic Ca
2+
and Membrane Dynamics in Patients With Primary Hypercholesterolemia
Authors: Sang Kim-Hanh Le Quan , Levenson Jaime , Megnien Jean-Louis , Simon Alain , Devynck Marie-Aude
Published: June 2011

Abstract
This study was designed to evaluate the relationships between platelet cytosolic Ca
2+
concentration ([Ca
2+
]
i
) and plasma lipids in patients with primary hypercholesterolemia. In a double-blind, placebo-controlled trial, we determined platelet [Ca
2+
]
i
in the presence and virtual absence of extracellular Ca
2+
and the effects of prolonged treatment with pravastatin, a selective inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase. Platelet [Ca
2+
]
i
and membrane microviscosity were determined in 22 normotensive hypercholesterolemic men. Platelet [Ca
2+
]
i
was observed to vary with in vivo plasma lipid characteristics: in untreated patients, [Ca
2+
]
i
determined at low extracellular Ca
2+
concentration was significantly associated with plasma triacylglycerols (
P
=.008) and with the total cholesterol to HDL cholesterol ratio (
P
=.044). Triacylglycerol levels also correlated inversely with the external Ca
2+
-dependent [Ca
2+
]
i
rise. Pravastatin treatment reduced plasma total cholesterol (−20±3%), LDL cholesterol (−30±3%), triacylglycerols (−17±6%), and apoB levels (−25±4%) and simultaneously decreased platelet [Ca
2+
]
i
measured in a low-Ca
2+
medium by 14±6% (
P
=.03). However, [Ca
2+
]
i
values remained positively correlated with the total cholesterol to HDL cholesterol ratio (
P
=.04). Pravastatin treatment did not induce marked changes in membrane microviscosity, although the changes in trimethylaminodiphenylhexatriene anisotropy were inversely correlated with those of HDL cholesterol. These results indicate that plasma lipids can modulate cytosolic Ca
2+
in platelets by affecting Ca
2+
transport pathways that are dependent and independent of Ca
2+
influx.
Relations Between Deletion Polymorphism of the Angiotensin-Converting Enzyme Gene and Insulin Resistance, Glucose Intolerance, Hyperinsulinemia, and Dyslipidemia
Authors: Katsuya Tomohiro , Horiuchi Masatsugu , Chen Y.-D. I. , Koike George , Pratt Richard E. , Dzau Victor J. , Reaven Gerald M.
Published: June 2011

Abstract
Recent reports have shown that the frequency of the homozygous deletion genotype (DD) of the angiotensin-converting enzyme (ACE) gene is highly associated with myocardial infarction and cardiomyopathy, particularly in those considered to be at low risk for coronary heart disease (CHD) on the basis of their apoB or LDL cholesterol concentrations. The present study was initiated to extend this inquiry by exploring the possibility that the ACE/DD genotype might be associated with risk factors not evaluated in the initial reports. Consequently, we determined the ACE genotype in 181 subjects, 124 with normal glucose tolerance and 57 with non–insulin-dependent-diabetes mellitus (NIDDM), and compared various aspects of glucose, insulin, and lipoprotein metabolism in the three ACE genotypes. In general, normal subjects with the DD genotype had a lower body mass index, were more insulin sensitive (as assessed by the insulin suppression test), and had lower plasma glucose and insulin responses to oral glucose. In addition, plasma triglyceride and cholesterol concentrations were lowest and HDL cholesterol concentrations highest in the DD group. However, the only statistically significant differences were between the ID and DD groups; the latter had lower values for body mass index, was more insulin sensitive, and had a lower plasma insulin response to oral glucose. Similar but insignificant trends were noted in the patients with NIDDM. The present results show that subjects with the ACE/DD genotype are not at increased risk for CHD because of insulin resistance, relative hyperglycemia and hyperinsulinemia, or a dyslipidemia characterized by a high triglyceride and low HDL cholesterol concentration. Indeed, the risk for CHD from these variables seems to be decreased in subjects with the ACE/DD genotype.
Mast Cell Granule Remnants Carry LDL Into Smooth Muscle Cells of the Synthetic Phenotype and Induce Their Conversion Into Foam Cells
Authors: Wang Yenfeng , Lindstedt Ken A. , Kovanen Petri T.
Published: June 2011

AbstractWe report the effect of mast cells on the uptake of LDL by smooth muscle cells (SMCs) and their conversion into foam cells in vitro. The mast cells were stimulated to exocytose their cytoplasmic secretory granules, and the granule remnants formed were recovered from the extracellular fluid and added to cultures of SMCs of either the synthetic or contractile phenotype in LDL-containing medium. In the presence but not in the absence of granule remnants, SMCs of the synthetic phenotype took up LDL with ensuing stimulation of intracellular cholesteryl ester synthesis and cytoplasmic accumulation of neutral lipid droplets. Using methylated LDL (mLDL), a modified species of LDL that binds to granule remnants but not to LDL receptors, we demonstrated that this uptake (leading to foam cell formation) occurred only when LDL was bound to granule remnants. After the addition of colloidal gold–LDL and granule remnants to the incubation system, electron microscopy revealed that within phagosomes of the SMCs there were granule remnants (diameter, 0.5 to 1 μm) coated with LDL, confirming that LDL had been carried into the cells with the remnants. SMCs of the contractile phenotype were less efficient than their synthetic counterparts at phagocytosing LDL-coated granule remnants and were not converted into foam cells. This difference in the rate of phagocytosis of granule remnants was present even in the absence of LDL, revealing that the more active phagocytosis by SMCs of the synthetic phenotype was not specifically related to uptake of lipids but rather reflected a general phenotype characteristic of these cells. These observations indicate a phagocytic mechanism by which SMCs of the synthetic phenotype are converted into cholesteryl ester–filled foam cells, and they also suggest that degranulation of mast cells plays a role in the development of fatty streak lesions.
Regression of Atherosclerosis in Female Monkeys
Authors: Williams J. Koudy , Anthony Mary S. , Honoré Erika K. , Herrington David M. , Morgan Timothy M. , Register Thomas C. , Clarkson Thomas B.
Published: June 2011

Abstract
The objective of this study was to determine the structural and functional changes that occur in the artery wall in response to plasma lipid lowering and hormone replacement in surgically postmenopausal monkeys with established coronary artery atherosclerosis. Eighty-eight surgically postmenopausal cynomolgus monkeys were fed an atherogenic diet for 24 months and were then allocated into 4 groups: group 1 (n=20), a baseline necropsy group; group 2 (n=25), a lipid-lowering diet only; group 3 (n=22), lipid lowering plus conjugated equine estrogen treatment equivalent to 0.625 mg/d for a woman; and group 4 (n=21), lipid lowering plus conjugated equine estrogen and medroxyprogesterone acetate treatment (equivalent to 2.5 mg/d for a woman). Treatment was for 30 months. Histomorphometric analysis of perfusion-fixed coronary arteries revealed that plaque size did not change significantly in any of the groups compared with group 1 (
P
>.20). Plasma lipid lowering permitted coronary artery remodeling to occur (coronary artery and lumen size doubled compared with group 1) (
P
<.05); however, hormone therapy did not augment remodeling. Quantitative angiographic analysis of coronary artery reactivity revealed that lipid lowering improved dilator responses to acetylcholine by 22±4% (
P
=.01) but not to nitroglycerin (
P
=.23). Hormone replacement did not further affect vascular reactivity to the agonists tested (
P
>.4), but addition of medroxyprogesterone acetate diminished the beneficial effects of conjugated estrogens on coronary flow reserve (
P
=.03). In summary, the major arterial sequelae of lipid lowering in female monkeys were artery and lumen enlargement and improved reactivity of large epicardial coronary arteries. Addition of hormone replacement to the dietary modification did not further augment these improvements, except for the dilator capacity of the coronary microcirculation.
No Association Between Plasma Lipoprotein(a) Concentrations and the Presence or Absence of Coronary Atherosclerosis in African-Americans
Authors: Moliterno David J. , Jokinen Eero V. , Miserez André R. , Lange Richard A. , Willard John E. , Boerwinkle Eric , Hillis L. David , Hobbs Helen H.
Published: June 2011

Abstract
Elevated plasma concentrations of lipoprotein(a) [Lp(a)] are associated with coronary atherosclerosis in Caucasians. Although African-Americans have a higher median plasma Lp(a) concentration than Caucasians, they do not have a greater incidence of coronary atherosclerosis. This study was performed to determine whether the plasma concentration of Lp(a) is associated with coronary atherosclerosis in African-Americans. The fasting plasma concentrations of Lp(a) and lipoproteins were measured in 140 African-American subjects (62 men, 78 women, aged 31 to 80 years) 18±16 months (mean±SD) after they underwent coronary angiography: 72 had angiographically normal coronary arteries and 68 had >70% luminal diameter narrowing of one or more major epicardial coronary arteries. The groups were similar in age, sex, and other risk factors for atherosclerosis. The subjects with coronary artery disease had higher plasma concentrations of total cholesterol, triglycerides, and VLDL and LDL cholesterol (
P
=.04) and lower concentrations of HDL cholesterol (
P
=.0001) than subjects without coronary artery disease, but there was no significant difference in the plasma concentration of Lp(a). The distribution of apolipoprotein(a) alleles by size was also not significantly different between the two groups. These results suggest that the plasma concentration of Lp(a) is not an independent risk factor for coronary artery disease in African-Americans.
Effects of Recombinant Hirudin (r-Hirudin, HBW 023) on Coagulation and Platelet Activation In Vivo
Authors: Eichinger Sabine , Wolzt Michael , Schneider Barbara , Nieszpaur-Los Malgorzata , Heinrichs Hubert , Lechner Klaus , Eichler Hans-Georg , Kyrle Paul A.
Published: June 2011

Abstract
In a double-blind, randomized, crossover study, we investigated in 15 healthy male volunteers the effects of recombinant (r-) hirudin (HBW 023, 0.35 mg/kg body wt SC), unfractionated heparin (UFH, HeparinNovo; 150 IU/kg body wt SC), and a low-molecular-weight heparin preparation (LMWH, Fragmin; 75 IU/kg body wt SC) on coagulation and platelet activation in vivo by measuring specific coagulation-activation peptides (prothrombin fragment 1+2 [F1+2], thrombin–antithrombin-III complex [TAT], and β-thromboglobulin [β-TG]) in bleeding-time blood (activated state) and venous blood (basal state). In bleeding-time blood, r-hirudin and the heparin preparations significantly inhibited formation of both TAT and F1+2. However, the inhibitory effect of r-hirudin on F1+2 generation was short-lived and weaker compared with that of UFH and LMWH, and the TAT-to-F1+2 ratio was significantly lower after r-hirudin than after UFH or LMWH. Thus, in vivo, when the coagulation system is in an activated state, r-hirudin exerts its anticoagulant effects predominantly by inhibiting thrombin (factor IIa), whereas UFH and LMWH are directed against both factors Xa and IIa. A different mode of action for UFH and LMWH was not detectable. In venous blood, r-hirudin caused a moderate reduction in TAT formation and an increase (at 1 hour) rather than a decrease in F1+2 generation. Formation of TAT and F1+2 was suppressed at various time points following both UFH and LMWH. There was no difference in the TAT-to-F1+2 ratio after r-hirudin and heparin. Thus, a predominant effect of r-hirudin on factor IIa (as found in bleeding-time blood) was not detectable in venous blood. In bleeding-time blood, r-hirudin (but neither UFH nor LMWH) significantly inhibited β-TG release. In contrast, both UFH and LMWH caused an increase in β-TG 10 hours after heparin administration. Our observation of reduced platelet function after r-hirudin compared with delayed platelet activation following UFH and LMWH suggests an advantage of r-hirudin over heparin, especially in those clinical situations (such as arterial thromboembolism) where enhanced platelet activity has been shown to be of particular importance.
Inhibition of Atherosclerosis and Myocardial Lesions in the JCR:LA-cp Rat by β,β′-Tetramethylhexadecanedioic Acid (MEDICA 16)
Authors: Russell James C. , Amy Roger M. , Graham Sandra E. , Dolphin Peter J. , Wood George O. , Bar-Tana Jacob
Published: June 2011

Abstract
Atherosclerosis-prone, insulin-resistant JCR:LA-cp male rats were treated from 6 weeks to 39 weeks of age with β,β′-tetramethylhexadecanedioic acid (MEDICA 16). Body weights were reduced (13%,
P
<.001) at 36 weeks without any accompanying decrease in food consumption. The treatment did not cause any significant change in plasma glucose or fasting insulin concentrations. There was a significant decrease in the extreme hyperplasia of the islets of Langerhans (38%,
P
<.05). The marked VLDL hypertriglyceridemia was decreased by 70% (
P
<.001), with an accompanying significant reduction in cholesterol concentrations. The severity of raised atherosclerotic lesions on the aortic arch was very markedly reduced (
P
<.01) in treated rats. This was accompanied by a reduction (
P
<.01) in the incidence of ischemic myocardial lesions. We conclude that long-term (33 weeks) MEDICA 16 treatment of an animal model for the obesity/insulin-resistant/hyperlipidemic syndrome not only markedly improved lipid metabolism, but also inhibited the development of advanced cardiovascular disease.
Effects of Injury on ApoB Kinetics and Concentration in Rabbit Aorta
Authors: Olsson Gun , Wiklund Olov , Bondjers Göran
Published: June 2011

Abstract
Endothelial injury or dysfunction and deposition of lipoproteins and cholesterol are key events during the development of atherosclerosis. We have studied the lipoprotein kinetics in arterial tissue in relation to endothelial injury and re-endothelialization. Endothelial injury was induced in rabbits by use of a balloon catheter. With a specific immunoradiometric assay, apoB levels in arterial tissue were measured at different time points for up to 10 weeks after injury. Forty-five minutes before being killed, the rabbits were injected with
125
I-LDL, and influx of LDL was calculated from the accumulation of radioactivity in the arterial tissue. The concentration of apoB in the injured arterial tissue was four times higher than that in control arterial tissue (
P
<.0001). Within the lesion the concentration was as high in nonendothelialized as in re-endothelialized regions. The tissue pool of apoB was divided into a loosely bound fraction and a tightly bound fraction. The increase of apoB in the injured areas was primarily due to an increase in the tightly bound fraction. The influx of apoB was severalfold higher in nonendothelialized tissue than in re-endothelialized tissue or control areas (
P
<.005). When retention time was calculated, this was found to dramatically increase (by seven times) the tightly bound pool of apoB in the re-endothelialized areas. In addition to the large increase of a tightly bound apoB pool in injured areas, we found a prolonged retention time of apoB in the lesions, but only in the re-endothelialized areas. This might be due to different composition of the interstitial matrix as well as different diffusion characteristics in the re-endothelialized areas. A prolonged retention time may be important for the local modification of LDL and for the generation of a more atherogenic lipoprotein.
Uptake of Radiolabeled and Colloidal Gold–Labeled Chyle Chylomicrons and Chylomicron Remnants by Rat Platelets In Vitro
Authors: Xu Ning , Zhou Li , Odselius Rolf , Nilsson Åke
Published: June 2011

Abstract
This study examined the uptake of chyle chylomicrons (CMs) and chylomicron remnants (CMRs) by rat platelets in vitro. CMs and CMRs were doubly labeled with [
3
H]arachidonate ([
3
H]-20:4) and [
14
C]cholesterol and were incubated with platelets for up to 4 hours. A significant uptake (binding and/or internalization) of CMs by the platelets occurred, as indicated by the parallel increase of [
3
H]20:4 and [
14
C]cholesterol in platelets with incubation time. Addition of unlabeled CMs, VLDLs, LDLs, and HDLs decreased the uptake of labeled CMs. The competition experiments suggested that there is both a saturable binding and a nonspecific uptake of CMs. During incubation with CMs, the proportion of [
3
H]20:4 in phospholipids decreased and that in 1,2-x-diacylglycerol increased. The data indicated that a phospholipase C–mediated degradation of phosphatidylcholine and phosphatidylethanolamine occurred, whereas [
3
H]20:4 in triglyceride and
14
C in cholesteryl ester did not change. Electron microscopic studies after incubation with colloidal gold–labeled CMs (CM-Au’s) demonstrated an accumulation of CM-Au particles in the open canalicular system of the platelets. Some CM-Au particles were localized in cytoplasmic vacuoles that were not stained by ruthenium red. Some CM-Au’s or free gold particles were in vacuoles that showed acid phosphatase activity, indicating that some true endocytosis of CM occurred. The uptake of [
3
H]-20:4– and [
14
C]cholesterol-labeled CMRs was low compared with the uptake of CMs. After incubation with colloidal gold–labeled CMRs (CMR-Au’s), only a few platelets contained CMR-Au in their open canalicular systems, and no CMR-Au particles were seen in the cytoplasm or in acid phosphatase–positive vacuoles. Rat platelets can thus interact with CMs by a process that leads to a sequestration in the open canalicular system and endocytosis and a net degradation of CM phospholipids. The conversion of CMs to CMRs counteracts this interaction.
Polymorphisms of the Apolipoprotein E Gene and Severity of Coronary Artery Disease Defined by Angiography
Authors: Wang X. L. , McCredie R. M. , Wilcken D. E. L.
Published: June 2011

AbstractIn a recent study, we could account for only about 50% of the variance in angiographically determined severity of coronary artery disease (CAD) with use of lipid and clinical variables as predictors. To explore the possible contribution of the apolipoprotein (apo) E polymorphisms to the severity of CAD (rather than to its occurrence), we studied 424 white patients aged 65 years or less consecutively referred for coronary angiography. Among the 304 male and 120 female patients, there were 110 with no significant CAD and 118 with one, 96 with two, and 100 with three significantly diseased major coronary arteries (>50% luminal obstruction). The allele frequencies were 0.068 for E2, 0.759 for E3, and 0.172 for E4. The E2 frequency was slightly lower and E4 higher than the frequencies reported for healthy white populations (E2: 0.072 to 0.130; E4: 0.136 to 0.160). There was a clear association between the apo E genotype and the number of significantly diseased vessels (regression coefficient=.12,P=.008). The frequency of the E4 allele increased linearly with the increase in CAD severity in both sexes (for none, one, two, and three significantly diseased vessels; female patients: 0.136, 0.161, 0.200, and 0.324; male patients: 0.136, 0.167, 0.132, and 0.229, respectively,P<.01). The frequencies of the E2 allele, on the other hand, decreased with increasing severity (for none, one, two, and three significantly diseased vessels; female patients: 0.091, 0.018, 0.050, and 0.029; male patients: 0.073, 0.089, 0.072, and 0.054, respectively,P<.05). While much of the correlation was mediated through apo E–related changes in circulating levels of apo B and apo B–containing lipoproteins, after controlling for these lipid variables, there was an independent association between apo E genotype and CAD severity (P<.05). Among the 311 CAD patients who were not receiving lipid-lowering drugs at the time of testing, the E2 allele was significantly associated with low apo B levels (−21% for male patients,P<.01, and −9% for female patients,P<.05) compared with E3E3 genotypes, whereas the E4 allele was associated with high apo B levels (+12.4% for male patients,P<.05, and +19.8% for female patients,P<.01). We conclude that among patients with coronary disease, the apo E4 allele is associated with more severe and the E2 allele with less severe disease. While the apo E genotype had an important effect on the level of circulating apo B–containing lipoprotein levels, these associations with severity were mediated not only by changes in circulating apo B but also by mechanisms unrelated to circulating lipids in this population of CAD patients.
Dose-Response Relationships of Serum Lipid Measurements With the Extent of Coronary Stenosis
Authors: Bolibar Ignasi , Thompson Simon G. , von Eckardstein Arnold , Sandkamp Martin , Assmann Gerd
Published: June 2011

Abstract
Serum lipids, lipoproteins, and more recently apolipoproteins and lipoprotein(a) [Lp(a)] have been shown to be independent risk factors for coronary vessel disease and its prognosis. However, the relationships between serum lipid levels and the extent of coronary artery disease (CAD) have not been consistently shown. Twenty-five hundred male and female patients with suspected angina pectoris were recruited from 18 European medical centers. The independent relations of total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, apo A-I and B, and Lp(a) with the presence and extent of CAD, as assessed by coronary angiography, were investigated. All of the lipid measures showed strong relations (
P
<.0001) with the presence of CAD, defined by the existence of at least one ≥50% coronary vessel stenosis. Total cholesterol, LDL cholesterol, apo B, triglycerides, and Lp(a) were substantially higher and HDL cholesterol and apo A-I lower in patients with CAD. The odds ratio of CAD, in the high-risk tertile of each lipid’s distribution compared with the low-risk tertile, was in the range 1.5 to 2.3. Each of total cholesterol (or LDL cholesterol or apo B), HDL cholesterol (or apo A), and Lp(a) had an independent effect in predicting the presence of CAD. In addition, all lipids showed a strong association (
P
=.0006 for triglycerides,
P
<.0001 otherwise) with the extent of CAD as defined by the number of stenosed coronary vessels. These relations, which conform to a “dose-response” effect, remained after adjusting for other coronary risk factors. This study provides direct evidence of the role of serum lipid levels in determining not only the presence but also the extent of atherosclerotic disease in coronary arteries.
Lowering of HDL
2b
by Probucol Partly Explains the Failure of the Drug to Affect Femoral Atherosclerosis in Subjects With Hypercholesterolemia
Authors: Johansson Jan , Olsson Anders G. , Bergstrand Lott , Elinder Liselotte Schäfer , Nilsson Sven , Erikson Uno , Mölgaard Jörgen , Holme Ingar , Walldius Göran
Published: June 2011

Abstract
The aim of the Probucol Quantitative Regression Swedish Trial (PQRST) (n=303) was to investigate whether probucol (0.5 g BID) added to diet and cholestyramine (8 g BID) could retard progression or induce regression of femoral atherosclerosis in hypercholesterolemic (>6.86 mmol/L) subjects. Probucol did not induce regression over the 3-year trial period as estimated by change in lumen volume on quantitative arteriography of a 20-cm segment of the femoral artery. In this report we studied in a representative subgroup (n=72) whether the reduction in HDL concentrations induced by probucol could explain the failure of the drug to be effective. We analyzed the effects of treatment on HDL particle size subclasses. Probucol lowered the relative level of HDL
2b
, comprising the largest HDL particles, by 53% and the protein concentration of HDL
2b
by 67%. The protein reduction in HDL was mainly confined to the apolipoprotein A-I moiety. The change in lumen volume correlated significantly with change in HDL, ie, HDL cholesterol (
r
=.34,
P
<.01), HDL
2
cholesterol (
r
=.37,
P
<.01), HDL
2b
protein (
r
=.44,
P
<.001), and the relative HDL
2b
value (
r
=.51,
P
<.001). The corresponding values for relative HDL
2b
distribution calculated on the active (n=35) and placebo (n=37) groups separately were also significant (
r
=.39 and .32, respectively; both
P
<.05). The correlation between drug-induced change in the relative HDL
2b
concentration and change in atherosclerosis was independent of the alteration in triglyceride concentration and could not be explained by treatment interaction. HDL
2b
lowering was highly significantly correlated to probucol concentration. We suggest that the lowering effects of probucol on HDL and particularly on the HDL
2b
fraction at least in part explain why regression of femoral atherosclerosis was not obtained by the drug.
Body Fat Distribution Is a Determinant of the High-Density Lipoprotein Response to Dietary Fat and Cholesterol in Women
Authors: Clifton Peter M. , Abbey Mavis , Noakes Mannie , Beltrame Sandra , Rumbelow Nicole , Nestel Paul J.
Published: June 2011

AbstractWe have conducted a dietary trial that addressed the factors influencing the variability in plasma lipids in response to dietary fat and cholesterol with a focus on the effects of gender and body fat distribution. Sixty-seven women and 53 men were selected so that overall men and women had a similar mean age, LDL cholesterol, and body mass index. After a 2-week low-fat period subjects were given two liquid supplements for 3 weeks each, one that contained 31 to 40 g fat and 650 to 845 mg cholesterol, and one that was fat free. Measurements included plasma lipids and lipoproteins, glucose, insulin, hepatic triglyceride lipase activity, apolipoprotein E polymorphism, and three indexes of body fat (body mass index, waist girth, and waist-hip ratio). In response to dietary fat and cholesterol supplementation only the changes in HDL cholesterol, especially in HDL2, differed between the sexes. Although on univariate analysis lipoprotein changes were predicted by baseline lipoprotein levels, body mass index, waist girth, waist-hip ratio, hepatic triglyceride lipase activity, and insulin, multiple regression showed only waist-hip ratio to predict changes in HDL2cholesterol in women and body mass index and baseline HDL2cholesterol in men. Changes in LDL were predicted by baseline LDL cholesterol in women and apolipoprotein E phenotype and age in men. These studies explain much of the variability that individuals show in lipoprotein changes, especially in the more desirable changes in cholesterol transport in HDL2, in response to eating saturated fat and cholesterol.
Mildly Oxidized LDL Induces Platelet Aggregation Through Activation of Phospholipase A
2
Authors: Weidtmann A. , Scheithe R. , Hrboticky N. , Pietsch A. , Lorenz R. , Siess W.
Published: June 2011

Abstract
Native LDL and LDL oxidized under various conditions were compared in terms of their ability to activate platelets. Native LDL did not induce platelet shape change or aggregation, even at high concentrations (2 mg protein/mL). LDL was mildly oxidized with either CuSO
4
(mox-LDL) or 3-(
N
-morpholino)sydnonimine (SIN-1–LDL). Analysis of mox-LDL and SIN-1–LDL showed a small increase of dienes (E
234nm
from 0.28±0.04 to 0.55±0.09, mean±SD) and thiobarbituric acid–reactive substance (from 0 to 10.6±1.5 nmol/mg, mean±SEM), no change in apo B electrophoretic mobility, and a minor (12% to 30%) decrease in polyunsaturated fatty acid content. Interestingly, this small oxidative modification of LDL dramatically changed its effect on platelets. Irreversible aggregation and secretion were induced by a threshold concentration of 0.4 mg protein/mL. In contrast, LDL thoroughly oxidized with CuSO
4
(ox-LDL) did not aggregate platelets. Although mox-LDL was depleted in antioxidants (α- and γ-tocopherol, α- and β-carotene, and other carotenoids), incubation of mox-LDL with exogenous α-tocopherol did not reverse its ability to induce platelet aggregation and secretion. Preincubation of platelets with the cyclooxygenase inhibitor aspirin or the phospholipase A
2
inhibitors trifluoperazine, quinacrine, 4-bromophenacyl bromide, and propranolol completely prevented platelet aggregation and secretion caused by mox-LDL or SIN-1–LDL. These results indicate that mildly oxidized LDL activates platelets through a phospholipase A
2
/cyclooxygenase–dependent pathway. The complete inhibition of mox-LDL–induced platelet aggregation by aspirin could contribute to its beneficial effect in cardiovascular disease.
In Situ Localization and Quantification of mRNA for 92-kD Type IV Collagenase and Its Inhibitor in Aneurysmal, Occlusive, and Normal Aorta
Authors: McMillan William D. , Patterson Bruce K. , Keen Richard R. , Shively Vera P. , Cipollone Maria , Pearce William H.
Published: June 2011

Abstract
Ninety-two-kilodalton type IV collagenase (MMP-9) is present in aortic aneurysms and may be important to the pathogenesis of this disease. Alteration in expression of MMP-9 or its inhibitor, the tissue inhibitor of metalloproteinase type 1 (TIMP-1), could increase degradation of extracellular matrix and lead to aneurysm formation. The purpose of this study was (1) to measure tissue levels of MMP-9 and TIMP-1 mRNA in aneurysmal (AAA), atherosclerotic occlusive (AOD), and normal (NL) human infrarenal aorta; (2) to test for their expression by cultured AAA and NL vascular smooth muscle cells (VSMCs); and (3) to locate in situ the cells responsible for mRNA production within AAA, AOD, and NL aortic wall. Total RNA extracted from AAA (n=8), AOD (n=8), and NL (n=7) tissue was subjected to Northern analysis. Signals for MMP-9 and TIMP-1 were normalized to α-tubulin. Mean values±SEM were compared by ANOVA. NL and AAA VSMCs were cultured, passaged, and grown to confluence before RNA extraction and Northern analysis. In situ hybridization with digoxigenin-labeled RNA probes localized cells responsible for MMP-9 and TIMP-1 mRNA expression within sections of AAA (n=5), AOD (n=2), and NL (n=2) aorta. MMP-9 mRNA levels were significantly greater in AAA (0.855±0.180) than NL (0.046±0.23) (
P
<.02), but differences between AOD (0.406±0.196) and AAA or AOD and NL were not significant. Differences in TIMP-1 mRNA levels between tissue types were not significant (AAA, 1.17±0.123; AOD, 1.79±0.351; NL, 0.652±0.378). Cultured AAA and NL aortic VSMCs constitutively expressed mRNA for TIMP-1 but not MMP-9. In situ hybridization of AAA and AOD tissue localized MMP-9 mRNA to adventitial macrophages in areas of neovascularization and TIMP-1 mRNA to adventitial VSMCs. MMP-9 mRNA levels are significantly greater in aneurysmal than normal aorta. Cultured VSMCs constitutively express TIMP-1 but not MMP-9. In the diseased aortic wall, MMP-9 mRNA is found in adventitial macrophages and TIMP-1 mRNA in adventitial VSMCs. Localization of MMP-9 mRNA expression to discrete areas surrounding vasa vasorum suggests that the enzyme is responsible for localized matrix alterations associated with neovascularization.
Development and Progression of Atherosclerosis in Aorta From Heterozygous and Homozygous WHHL Rabbits
Authors: Dowell F. J. , Hamilton C. A. , Lindop G. B. M. , Reid J. L.
Published: June 2011

Abstract
This study was conducted to define progression of atherosclerosis in both homozygous and heterozygous Watanabe heritable hyperlipidemic (WHHL) rabbits and to investigate the ability of the HMG CoA reductase inhibitor simvastatin to attenuate progression of the disease. We examined contractile responses to phenylephrine and endothelium-dependent relaxation in response to carbachol in thoracic aorta at 3, 6, 9, and 12 months in control New Zealand White (NZW) rabbits, homozygous WHHL rabbits, and heterozygous WHHL rabbits. Homozygous and heterozygous rabbits were treated with simvastatin (10 mg/kg per day) from 3 to 6 months and from 9 to 12 months of age. Simvastatin significantly reduced serum cholesterol levels in young heterozygotes, with a nonsignificant trend toward a reduction in older heterozygotes. In homozygotes, no significant fall was observed. Contractile function declined progressively with age in all groups−most in homozygotes and least in NZW rabbits. Relaxation was unaffected by age in NZW rabbits; relaxation declined in the heterozygotes and declined to a greater extent in homozygotes. Simvastatin retarded the loss of function in the young heterozygotes. Similar trends were observed in young homozygotes and older heterozygotes, with no effect in older homozygotes. Histological studies revealed the progressive development of early atherosclerosis in heterozygotes, and more advanced atherosclerosis was observed in homozygotes. Simvastatin did not inhibit development of atheroma. A correlation was observed between vascular function and structure. However, functional changes preceded the development of atheroma. In addition, we have demonstrated that simvastatin can help to reduce the loss of vascular function associated with the progression of atherosclerosis in the heterozygous WHHL rabbit.
Mibefradil Prevents Neointima Formation After Vascular Injury in Rats
Authors: Schmitt R. , Clozel J.-P. , Iberg N. , Bühler F. R.
Published: June 2011

Abstract
Mibefradil is a novel calcium antagonist that is selective for the T-type voltage-operated calcium channel rather than the L type. Because T-type calcium channels are present on rapidly proliferating cells and mediate the increase of intracellular calcium induced by some growth factors, such as platelet-derived growth factor, we hypothesized that the blockade of T channels could prevent the excessive smooth muscle cell proliferation that occurs in conditions such as vascular injury. To test this hypothesis, we evaluated in rats the effects of mibefradil (which blocks both L- and T-type channels) on neointima formation after vascular injury, and we compared them with those of equihypotensive doses of amlodipine and verapamil (which block only L-type channels). Mibefradil (30 mg/kg) decreased the area of neointima formed 14 days after balloon injury by 54% (
P
<.001). In contrast, neither verapamil nor amlodipine had an effect despite a blood pressure reduction at least equal to that of mibefradil. The in vivo effect of mibefradil was indeed an inhibition of smooth muscle cell proliferation, as shown by thymidine incorporation experiments. This antiproliferative effect of mibefradil was also observed in vitro in smooth muscle cells stimulated by fetal calf serum. In this condition also, verapamil was ineffective. We conclude that in rats mibefradil has a potent antiproliferative effect on smooth muscle cells after vascular injury. This effect might be due to blockade of voltage-operated T channels.
Iron Overload Augments the Development of Atherosclerotic Lesions in Rabbits
Authors: Araujo Jesús A. , Romano Egidio L. , Brito Beatriz E. , Parthé Valentín , Romano Mirtha , Bracho María , Montaño Ramón F. , Cardier José
Published: June 2011

AbstractIron, a major oxidant in vivo, could be involved in atherosclerosis through the induction of the formation of oxidized LDL, a major atherogenic factor. This study was designed to test this hypothesis experimentally. Four groups of New Zealand White rabbits were included: iron-overloaded/hypercholesterolemic (group A, n=8), iron-overloaded (group B, n=6), hypercholesterolemic (group C, n=6), and untreated (group D, n=6). Iron overload was achieved by the intramuscular administration of 1.5 g of iron dextran divided in 30 doses. Hypercholesterolemia was produced by feeding rabbit chow enriched with 0.5% (wt/wt) cholesterol. Serum iron, ferritin, cholesterol, triglycerides, and lipoperoxides in serum were measured throughout the study. Lipoperoxides were measured at the end of the study in liver, aorta, and spleen homogenates. Aortas of groups A and C had multiple lesions; however, group A had greater lesional involvement than group C (P<.05). Lesions were not observed in rabbits fed normal chow (group D). As expected, serum iron and ferritin were above normal levels in groups A and B. Serum cholesterol increased in groups A and C. Lipoperoxides in liver and spleen homogenates of iron-overloaded rabbits were increased. Interestingly, iron deposits were seen by ultrastructural studies in the arterial walls of rabbits in groups A and B. Our study suggests that iron overload augments the formation of atherosclerotic lesions in hypercholesterolemic rabbits.
Genetic Differences of Lipid Metabolism in Macrophages From C57BL/6J and C3H/HeN Mice
Authors: Ishii Itsuko , Ito Yasuhiko , Morisaki Nobuhiro , Saito Yasushi , Hirose Seiyu
Published: June 2011

Abstract
Cholesterol metabolism in macrophages from atherosclerosis-prone C57BL/6J mice was compared with that in macrophages from atherosclerosis-resistant C3H/HeN mice. Plasma total cholesterol levels of both types of mice were significantly increased, but HDL cholesterol level was increased only in C3H/HeN mice when a high-cholesterol diet (1% cholesterol) was fed for 5 weeks. After incubation of macrophages from male and female mice on the high-cholesterol diet with β-VLDL for 24 hours, cholesterol content in macrophages from C57BL/6J was approximately 1.5- to 2.0-fold higher than in those from C3H/HeN mice. [
3
H]Cholesterol oleate–β-VLDL incorporation into macrophages from C57BL/6J mice on the high-cholesterol diet was greater than incorporation into those from C3H/HeN mice. The release of [
3
H]cholesterol from macrophages from C57BL/6J mice on the high-cholesterol diet was one seventh that from macrophages from C57BL/6J mice on the basal diet or that from macrophages from C3H/HeN mice on the basal or high-cholesterol diet. Acid cholesterol esterase activity was almost the same in macrophages from any group. Acyl CoA:cholesterol acyltransferase activity in macrophages from C57BL/6J mice on the high-cholesterol diet increased compared with that from macrophages from C57BL/6J mice on the normal diet. Neutral cholesterol esterase activity in macrophages from C57BL/6J mice was about half of that in macrophages from C3H/HeN mice independent of the type of diet. There were no sex differences in these metabolisms. Considered with our previous data, these results suggested that a high-cholesterol diet may cause metabolic changes to accumulate cholesterol ester in macrophages from C57BL/6J mice in accordance with genetic abnormalities.
Inhibition of Protein Tyrosine Kinase Alters the Effect of Serum Basic Protein I on Triacylglycerols and Cholesterol Differently in Normal and HyperapoB Fibroblasts
Authors: Kwiterovich Peter O. , Motevalli Mahnaz
Published: June 2011

Abstract
We studied whether the stimulatory effect of human serum basic protein I (BP I) on the formation of cell triacylglycerols and cholesterol may be mediated through protein tyrosine kinase in normal fibroblasts, and whether there was a deficiency in such a process in cells from subjects with hyperapobetalipoproteinemia (hyperapoB). Genistein, a highly specific inhibitor of tyrosine kinase phosphorylation, was used as a probe. When BP I (428.0 nmol/L) alone was added to F-12 medium without genistein, the mean mass of cell triacylglycerols doubled in six normal cell lines from healthy subjects, an effect that was decreased by 50% in six cell lines from subjects with hyperapoB (
P
=.007). The addition of genistein with BP I to normal cells decreased the stimulation of triacylglycerol formation by BP I by about 50% (
P
=.008), whereas genistein had little effect in the BP I–treated hyperapoB cells. The effect of genistein on the stimulation of triglyceride and cholesterol production by BP I was shown to be both time and concentration (92.5 nmol/mL medium nadir) dependent. In normal fibroblasts, BP I stimulated the rate of incorporation of both [
14
C]acetate (
P
=.0001) and [
3
H]mevalonolactone (
P
=.002) into unesterified cholesterol, an effect that was markedly deficient in the hyperapoB cells (
P
=.0001 for [
14
C]acetate and
P
=.0002 for [
3
H]mevalonolactone). In normal but not hyperapoB cells, genistein inhibited the significant stimulation by BP I of the rates of both [
14
C]acetate (
P
=.0001) and [
3
H]mevalonolactone (
P
=.04) incorporation into unesterified cholesterol. There was also a significantly greater stimulation by BP I of the rate of [
14
C]acetate incorporation into cell esterified cholesterol in normal cells than in hyperapoB cells (
P
=.003), an effect that was inhibited by genistein in both normal (
P
=.0009) and hyperapoB (
P
=.01) cells. BP I also stimulated to a greater extent the mass of total cholesterol (
P
=.0009) and unesterified cholesterol (
P
=.015), but to a lesser degree that of esterified cholesterol (
P
=.44), in normal cells than in hyperapoB cells. Herbimycin A and tyrphostin A47, two other inhibitors of protein tyrosine kinase, also significantly inhibited the effects of BP I on triacylglycerol and cholesterol mass in normal cells but not in hyperapoB cells. The effect of BP I on triacylglycerols and cholesterol formation in normal cells appeared to be mediated through a tyrosine kinase–dependent process that was deficient in hyperapoB cells.
Functional Properties of Human Vascular Endothelial Cadherin (7B4/Cadherin-5), an Endothelium-Specific Cadherin
Authors: Breviario F. , Caveda L. , Corada M. , Martin-Padura I. , Navarro P. , Golay J. , Introna M. , Gulino D. , Lampugnani M. G. , Dejana E.
Published: June 2011

Abstract
Human vascular endothelial cadherin (VE-cadherin, 7B4/cadherin-5) is an endothelial-specific cadherin localized at the intercellular junctions. To directly investigate the functional role of this molecule we cloned the full-length cDNA from human endothelial cells and transfected its coding region into Chinese hamster ovary cells. The product of the transfected cDNA had the same molecular weight as the natural VE-cadherin in human endothelial cells, and reacted with several VE-cadherin mouse monoclonal antibodies. Furthermore, it selectively concentrated at intercellular junctions, where it codistributed with α-catenin. VE-cadherin conferred adhesive properties to transfected cells. It mediated homophilic, calcium-dependent aggregation and cell-to-cell adhesion. In addition, it decreased intercellular permeability to high–molecular weight molecules and reduced cell migration rate across a wounded area. Thus, VE-cadherin may exert a relevant role in endothelial cell biology through control of the cohesion and organization of the intercellular junctions.