bluuebunny/crossref_metadata_2025 huggingface dataset:
Lysophosphatidylcholine increases vascular superoxide anion production via protein kinase C activation.
Authors: Ohara Y , Peterson T E , Zheng B , Kuo J F , Harrison D G
Published: June 2011

We tested the hypothesis that lysophosphatidylcholine (lyso-PC) could activate protein kinase C in intact vascular segments and sought to examine some of the physiological consequences of this activation. In segments of rabbit aorta, the patterns of protein phosphorylation determined by two-dimensional electrophoresis stimulated by lyso-PC and 12-O-tetradecanoylphorbol 13-acetate (TPA) were similar. Activation of protein kinase C can stimulate superoxide anion (O2-) production in other tissues, and we found that lyso-PC-treated rabbit aortas produced twofold more O2- than control vessels. Calphostin C, a potent and specific inhibitor of protein kinase C, attenuated O2- production in lyso-PC-treated vessels but had no effect in control vessels. The effect of lyso-PC on O2- production was mimicked by TPA. In separate bioassay studies, release of the endothelium-derived vascular relaxing factor (EDRF) quantified by the response of detector vessels was markedly impaired after exposure of donor rabbit aortic segments to lyso-PC. After incubation with calphostin C, EDRF release in response to acetylcholine from lyso-PC-treated donor vessels was restored significantly. Thus, lyso-PC can activate protein kinase C in intact vessels, leading to an increase in O2- production. Activation of protein kinase C by lyso-PC may also play a role in altering the release of EDRF in response to acetylcholine. Increased O2- production in response to lyso-PC may have important consequences in the atherogenic process.
ApoA-IV phenotype affects diet-induced plasma LDL cholesterol lowering.
Authors: Mata P , Ordovas J M , Lopez-Miranda J , Lichtenstein A H , Clevidence B , Judd J T , Schaefer E J
Published: June 2011

The National Cholesterol Education Program (NCEP) recommends that dietary total fat, saturated fat, and cholesterol intake be reduced to < or = 30% of calories, < 10% of calories, and < 300 mg/d, respectively (step 1 diet), in the general population to reduce plasma low-density lipoprotein cholesterol (LDL-C) levels and heart disease risk. We examined the LDL-C-lowering response to such a diet (26% fat, 8% saturated fat, and 201 mg/d cholesterol) compared with an average American diet (39% fat, 15% saturated fat, and 435 mg cholesterol/d) in 153 subjects using diet periods of 4 through 24 weeks for each diet phase. The mean LDL-C reduction was 13% in men (n = 93) and 7% in postmenopausal women (n = 60). The effect of apolipoprotein (apo) A-IV phenotype on responsiveness was examined. LDL-C lowering in men was significantly (P < .005) less (7%) for 17 apoA-IV (1/2) subjects than for 76 apoA-IV (1/1) subjects (16%). In women, 7% lowering was observed in both 12 apoA-IV (1/2) subjects and 48 apoA-IV (1/1) subjects. ApoA-IV phenotype had a significant effect on plasma high-density lipoprotein cholesterol levels during both dietary periods; women carrying the apoA-IV-2 allele had higher levels than those homozygous for the apoA-IV-1 allele. The opposite was true for triglyceride levels, but only during the period when the subjects consumed the high-fat, high-cholesterol diet.(ABSTRACT TRUNCATED AT 250 WORDS)
Resistance to insulin-stimulated glucose uptake and dyslipidemia in Asian Indians.
Authors: Laws A , Jeppesen J L , Maheux P C , Schaaf P , Chen Y D , Reaven G M
Published: June 2011

Persons from the Indian subcontinent have elevated coronary heart disease risk. We measured insulin resistance with the insulin suppression test in 22 Asian Indian men and women and an equal number of control subjects of European ancestry matched for age and body mass index. Asian men and women had increased glucose and insulin responses to oral glucose tolerance tests (P < .05 by ANOVA) and had approximately 60% higher steady-state plasma glucose levels during the insulin suppression test (P < .001 by ANOVA), consistent with insulin resistance. In response to mixed meals, Asian women had higher plasma free fatty acids and glycerol concentrations than women of European ancestry (P < .02 by ANOVA), whereas Asian Indian men had similar free fatty acid and glycerol levels compared with men of European ancestry despite higher plasma insulin levels. Thus, results in both sexes were consistent with resistance to insulin suppression of free fatty acid levels in Asian Indians. Asian Indians of both sexes had higher fasting plasma triglyceride (P < .01) and lower high-density lipoprotein cholesterol (P < .01) concentrations than men and women of European ancestry. Resistance to insulin-stimulated glucose uptake and to insulin suppression of free fatty acid levels in Asian Indians is associated with a number of metabolic abnormalities that are demonstrated risk factors for coronary heart disease, including increased glucose, insulin, and triglyceride concentrations and decreased high-density lipoprotein cholesterol concentrations.
Cyclosporin suppresses transplant arteriosclerosis in the aorta-allografted, cholesterol-clamped rabbit. Suppression preceded by decrease in arterial lipoprotein permeability.
Authors: Andersen H O , Madsen G , Nordestgaard B G , Hansen B F , Kjeldsen K , Stender S
Published: June 2011

The immunosuppressant cyclosporin has been suggested to aggravate as well as retard the development of transplant arteriosclerosis, the major long-term problem for patients with heart transplants. We examined the effect of human therapeutic levels of blood cyclosporin on the development of experimental transplant arteriosclerosis. The thoracic aorta from one rabbit was transplanted as an end-to-side bypass on the abdominal aorta of another rabbit, and plasma cholesterol was clamped at 5 to 7 mmol/L. Cyclosporin markedly suppressed the severity of transplant arteriosclerosis, judged both biochemically and histologically: cholesterol content in aortic transplants was reduced by 70% and 80% after 10 days and 20 days of cholesterol feeding, respectively (both comparisons, P < .01), and after 20 days of cholesterol feeding myointimal proliferation was totally inhibited in grafts from cyclosporin-treated animals, judged from maximal intimal thickness and intimal area on cross sections of grafts (both comparisons, P < .05). In another group of non-cholesterol-fed, aorta-transplanted rabbits, cyclosporin reduced by 90% (P < .01) an otherwise markedly increased permeability to low-density lipoprotein in transplanted aortas. These results suggest that cyclosporin causes a substantial decrease in the severity of transplant arteriosclerosis and that this effect is mediated at least partly via a large decrease in aortic lipoprotein permeability.
Relations of plasma TG and HDL-C concentrations to body composition and plasma insulin levels are altered in men with small LDL particles.
Authors: Katzel L I , Krauss R M , Goldberg A P
Published: June 2011

Low-density lipoprotein (LDL) subclass pattern B is characterized by a predominance of small, dense LDL particles (LDL peak particle size < or = 255 A), increased plasma triglyceride (TG) levels, reduced high-density lipoprotein (HDL) cholesterol levels, and glucose intolerance. This study tested the hypothesis that there are differences in the regulation of TG and HDL metabolism by insulin in patients with LDL pattern B. The study group comprised 160 healthy older (60 +/- 8 years, mean +/- SD) men. Forty-nine of the men (31%) had LDL pattern B. These men had a higher waist-to-hip ratio (WHR) (0.98 +/- 0.06 versus 0.95 +/- 0.06, P < .005) and lower maximal aerobic capacity (VO2max) (P < .005) than the 111 men of comparable age with a predominance of larger LDL particles (LDL peak particle size > 255 A, LDL pattern A). Men with LDL pattern B also had higher TG (1.76 +/- 0.60 versus 1.03 +/- 0.41 mmol/L, P < .0001) and lower HDL cholesterol (0.83 +/- 0.13 versus 1.06 +/- 0.29 mmol/L, P < .0001) and percent HDL2 subspecies (by gradient gel electrophoresis) (31 +/- 4 versus 43 +/- 6, P < .0001) levels than men with LDL pattern A, but the total cholesterol and LDL cholesterol levels did not differ between groups. Fasting glucose and insulin levels also did not differ between groups, but plasma glucose and insulin levels measured at 90 and 120 minutes during an oral glucose tolerance test were significantly higher in men with LDL pattern B.(ABSTRACT TRUNCATED AT 250 WORDS)
HDL and plasma phospholipids in coronary artery disease.
Authors: Kunz F , Pechlaner C , Erhart R , Fend F , Mühlberger V
Published: June 2011

Lipid fractions of native plasma and of high-density lipoprotein (HDL) were analyzed, and the clotting times of native platelet-rich and -poor plasma were recorded in patients with coronary artery disease and age-matched control subjects not taking any medication known to alter plasma lipid levels, coagulation, or platelet aggregation. Patients with coronary artery disease had lower HDL cholesterol and particularly HDL phospholipids but elevated HDL triglycerides, plasma triglycerides and diglycerides, and fibrinogen. Plasma lysolecithin was diminished. Accelerated coagulation was observed in native plasma and may be related to these changes in plasma lipids. The HDL content in cholesterol may be less relevant than that in phospholipids, which, because of their amphiphilic properties, may be essential for the removal and transport of hydrophobic cholesterol. The lower lysolecithin levels also suggest diminished esterification of cholesterol and reduced degradation of phospholipids, which may add to the poor lysability of platelet-rich and thus phospholipid-rich thrombi. Coagulation inhibition may be related to HDL phospholipids: in control subjects they correlated directly with clotting times of platelet-rich and -poor plasma and inversely with fibrinogen. In contrast, the enhanced thrombus formation in coronary artery disease may be related to altered HDL and plasma phospholipids, in particular to increased phosphatidylethanolamine. These adverse changes, particularly diminished HDL phospholipids, may result in increased deposition and reduced degradation and transport of lipids from arteriosclerotic lesions and thrombi and may therefore be significant in the development of coronary artery disease.
Radical-mediated oxidation of isolated human very-low-density lipoprotein.
Authors: Mohr D , Stocker R
Published: June 2011

Oxidative modification of human low-density lipoprotein (LDL) has received much attention because of its suggested involvement in the early events of atherogenesis. In contrast, little data exist concerning the oxidation of human very-low-density lipoprotein (VLDL), although such modification promotes foam cell formation by these lipoproteins. We therefore investigated the radical-mediated oxidation of VLDL by using controlled oxidizing conditions and sensitive and specific methods to assess lipoprotein lipid oxidation and antioxidation. We observed that the ratio of alpha-tocopherol to coenzyme Q10 in VLDL was close to that of LDL, suggesting that these lipoproteins may transport some coenzyme Q10 to extrahepatic tissues, as they do tocopherol. Most of the coenzyme Q10 associated with VLDL was present in its reduced, antioxidant active form, ubiquinol-10. The small amounts of ubiquinol-10 in VLDL provided the lipoprotein lipids with a highly efficient antioxidant protection. Also, the kinetics of radical-mediated lipid peroxidation in VLDL resembled that in LDL and therefore also probably proceeded via the recently described tocopherol-mediated peroxidation mechanism. Oxidation competition experiments using aqueous radicals and physiological concentrations and molar ratios of LDL and VLDL indicated that in contrast to the situation with high-density lipoproteins, lipid peroxidation was initiated and detected simultaneously in the former two lipoprotein particles. However, once initiated, peroxidation propagated at an approximately twofold higher rate in VLDL than LDL. Our studies suggest that radical-mediated lipid (per)oxidation proceeds via similar mechanisms in isolated LDL and VLDL. We conclude that efficient LDL antioxidants are also likely to be effective protective agents for VLDL.
Suitability of low-molecular-weight heparin(oid)s and a pentasaccharide for an in vitro human thrombosis model.
Authors: Lozano M , Bos A , de Groot P G , van Willigen G , Meuleman D G , Ordinas A , Sixma J J
Published: June 2011

There is much interest in in vitro thrombosis systems using exclusively human materials for evaluating new drugs. We have previously developed such a model using a perfusion chamber in which whole blood anticoagulated with low-molecular-weight heparin (LMWH) was circulated over the extracellular matrix of endothelial cells that had been stimulated with phorbol myristate acetate to cause tissue factor formation. Here we studied various LMWHs and a pentasaccharide to find out which was most useful in an in vitro thrombosis model. We compared unfractionated heparin, two commercial LMWHs (Fragmin and Fraxiparine), one commercial heparinoid (Orgaran), and a chemically synthesized derivative of the natural pentasaccharide (Org 31550). Blood was anticoagulated with the concentration of each glycosaminoglycan that prevented thrombin formation for at least 3 hours in the test tube (Fragmin, 20 anti-Xa U/mL; Fraxiparine, 40 anti-Xa Institute Choay U/mL; Orgaran, 15 anti-Xa U/mL; Org 31550, 200 anti-Xa U/mL; unfractionated heparin, 5 IU/mL) and recirculated over the matrix of unstimulated cells (no tissue factor in the matrix) and phorbol-stimulated endothelial cells (tissue factor in the matrix). Platelet adhesion, aggregate formation, and fibrin deposition were evaluated. In perfusions over the extracellular matrix of unstimulated cells, the highest platelet adhesion rates were observed with Orgaran. Fibrin deposition was absent with unfractionated heparin in phorbol-stimulated matrix. Increasing amounts of fibrin were observed with Orgaran, Fragmin, and Fraxiparine. Most fibrin was found with the pentasaccharide Org 31550.(ABSTRACT TRUNCATED AT 250 WORDS)
Elastic modulus of the radial artery wall material is not increased in patients with essential hypertension.
Authors: Laurent S , Girerd X , Mourad J J , Lacolley P , Beck L , Boutouyrie P , Mignot J P , Safar M
Published: June 2011

Hypertension is known to decrease arterial distensibility and systemic compliance. However, the arterial tree is not homogeneous, and it has been shown that the medium-size radial artery does not behave like the proximal, elastic, large, common carotid artery. Indeed, radial artery compliance in hypertensive patients (HTs) has been shown to be paradoxically increased when compared with that in normotensive control subjects (NTs) at the same blood pressure level. To determine whether this increase was due to hypertension-related hypertrophy of the arterial wall, radial artery functional and geometric parameters from 22 NTs (mean +/- SD, 44 +/- 11 years) were compared with those from 25 age- and sex-matched never-treated essential HTs (48 +/- 12 years) by using a high-precision ultrasonic, echo-tracking system coupled to a photoplethysmograph (Finapres system), which allows simultaneous arterial internal diameter, intima-media thickness, and finger blood pressure measurements. When the values for HTs were compared with those of NTs at their respective mean arterial pressures, HTs had similar internal diameter (2.50 +/- 0.56 versus 2.53 +/- 0.32 mm, mean +/- SD) and greater intima-media thickness (0.40 +/- 0.06 versus 0.28 +/- 0.05 mm, P < .001) measurements and increased arterial wall cross-sectional areas (3.79 +/- 1.14 versus 2.45 +/- 0.57 mm2, P < .001). Circumferential wall stress was not significantly different between the two groups. Compliance calculated for a given blood pressure, ie, 100 mm Hg (C100), was greater in HTs than NTs (3.46 +/- 2.41 versus 2.10 +/- 1.55 m2.kPa-1 x 10(-8), P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)
Complex segregation analysis provides evidence for a major gene acting on serum triglyceride levels in 55 British families with familial combined hyperlipidemia.
Authors: Cullen P , Farren B , Scott J , Farrall M
Published: June 2011

Familial combined hyperlipidemia (FCHL) was first described as an autosomal dominant inherited trait with primary action on triglyceride levels and secondary effects on cholesterol metabolism. This conclusion has since been questioned by several groups despite subsequent supportive biochemical and metabolic studies. To reexplore the genetics of FCHL, we assembled 55 families from the United Kingdom comprising 559 persons ascertained through probands with both hypercholesterolemia and hypertriglyceridemia. The results of univariate complex segregation analysis were consistent with a major gene acting on triglyceride and explaining two thirds of the genetic variability and 20% of the phenotypic variance in triglyceride levels. Univariate analysis did not identify a major genetic component acting on cholesterol levels. Bivariate segregation analysis rejected a major gene model. We also reexamined the original FCHL pedigrees collected by Goldstein et al and obtained results similar to those in the UK families. The prospects for mapping putative major genes determining triglyceride levels in FCHL patients by linkage analysis are discussed.
Factor VII coagulant activity and cholesterol changes in premenopausal women consuming a long-term cholesterol-lowering diet.
Authors: Brace L D , Gittler-Buffa C , Miller G J , Cole T G , Schmeisser D , Prewitt T E , Bowen P E
Published: June 2011

We periodically obtained blood samples from mildly hypercholesterolemic, but otherwise healthy, premenopausal women who were recruited to participate in a study of a long-term, cholesterol-lowering diet. All meals were prepared and most meals were consumed in the study center dining facility. Tests performed on blood samples included fibrinogen, cholesterol, factor VII coagulant activity (VIIc), and other measures of factor VII. We found that when women switched from a typical American diet (37% fat, polyunsaturated fatty acid to saturated fatty acid [P/S] ratio 0.5, 300 mg cholesterol/d) to a diet lower in fat and cholesterol (American Heart Association phase 2 diet: 30% fat, P/S ratio of 1, 150 to 200 mg cholesterol/d) and maintained that diet for 20 weeks, their plasma cholesterol levels decreased by approximately 6% after 4 weeks and remained at that level until study termination. Likewise, VIIc decreased by approximately 11% while factor VII antigen, total factor VII activity, and fibrinogen concentration did not change appreciably from baseline values. Our results show that premenopausal women benefit from a diet lower in total and saturated fat by a reduction in blood cholesterol and VIIc. Extrapolation from data on men in the Northwick Park Heart Study indicates that the 11% decrease in VIIc activity would correspond to an approximately 30% decrease in risk of mortality from coronary heart disease.
Development of the atherosclerotic core region. Chemical and ultrastructural analysis of microdissected atherosclerotic lesions from human aorta.
Authors: Guyton J R , Klemp K F
Published: June 2011

Lipid deposits in human atherosclerotic fibrous plaques exhibit marked differences in chemistry and ultrastructure from lipid deposits in fatty streaks, leading some investigators to question whether fibrous plaques originate from fatty streaks. To examine lesion transition, we employed lipid microanalysis, electron microscopy, and immunohistochemistry on fatty streaks, fibrolipid lesions (small raised lesions), and fibrous plaques from human aorta. Both fatty streaks and caps of fibrolipid lesions were high in esterified cholesterol content (mean, 62% of total cholesterol) and high in cholesteryl oleate content compared with cholesteryl linoleate content. Fatty streaks and fibrolipid lesion caps also showed similar morphology, characterized mostly by macrophage-derived foam cells in the superficial intima. Core lipids in both small and large raised lesions differed markedly from this pattern. Fibrolipid lesion cores showed mostly vesicular extracellular deposits, sometimes accompanied by cholesterol clefts, while fibrous plaque core deposits were also extracellular but had a variable appearance. Compared with fatty streaks, fibrolipid lesion cores showed significantly increased free/total cholesterol fractions (63%) and decreased fractional contents of cholesteryl oleate. Fibrous plaque cores had variable distributions of free and esterified cholesterol but significantly decreased cholesteryl oleate fractions compared with fatty streaks. The results support the concept of lesion transition, which is marked by deep intimal, extracellular deposition of cholesterol-rich, vesicular lipid deposits in small raised lesions. In the core region of larger raised lesions, both cholesterol-rich and cholesteryl ester-rich lipid deposits appear to form in the extracellular space.
Combined effects of lipid transfers and lipolysis on gradient gel patterns of human plasma LDL.
Authors: Lagrost L , Gambert P , Lallemant C
Published: June 2011

The triglyceride content of the plasma very-low-density lipoprotein (VLDL) fraction is the most important factor affecting the size of low-density lipoprotein (LDL) in humans. Because cholesteryl ester transfer protein (CETP) can influence the size distribution of LDL particles in human plasma, the implication of lipid transfers in the formation of small-sized LDL patterns, which have been associated with elevated plasma triglyceride levels, was investigated. The size distribution of LDL particles in 15 plasma samples was determined by electrophoresis of the plasma LDL fraction on 20 to 160 g/L polyacrylamide gradient gels. The apparent diameter of the major LDL subfraction was shown to correlate negatively with triglyceride concentrations (r = -.706, P < .005) and positively with both high-density lipoprotein cholesterol levels (r = .637, P < .02) and the high-density lipoprotein/VLDL + LDL cholesterol ratio (r = .768, P < .001). In addition, LDL size correlated negatively with both the ability of plasma LDL to donate cholesteryl esters (r = -.79, P < .001) and its ability to acquire triglycerides (r = -.72, P < .005). Whereas these observations indicated that CETP-mediated alterations of the triglyceride/cholesteryl ester ratio of the LDL core would contribute to changes in LDL diameter, they suggested that the formation of small-sized gradient gel LDL patterns would require another biochemical event, such as lipolysis, in addition to neutral lipid transfers. To test this hypothesis, total plasma samples with or without added VLDL (added triglyceride concentration, 2.0 g/L) were preincubated for 24 hours at 37 degrees C. Preincubation mainly induced the replacement of cholesteryl esters by triglycerides in the LDL core, and changes in LDL composition were greater when total plasma was supplemented with VLDL. Subsequently, isolated LDL was incubated in the presence of bovine milk lipoprotein lipase as a source of triglyceride hydrolysis activity. Lipolysis tended to reduce the size of the major LDL subpopulation, and the mean change in LDL diameter was significantly greater when plasma was preincubated with VLDL supplementation than when it was not (-0.6 +/- 0.3 versus -0.2 +/- 0.2 nm, respectively; (P < .01). Moreover, sequential effects of lipid transfer and lipolysis activities induced dramatic changes in the general shape of gradient gel LDL patterns. The largest plasma LDL subpopulations tended to disappear, and the formation of new, small LDL particles could be observed. The combined effects of neutral lipid transfers and triglyceride hydrolysis could account for variations of gradient gel LDL profiles in human plasma.(ABSTRACT TRUNCATED AT 400 WORDS)
Purification, cloning, and expression of a human enzyme with acyl coenzyme A: cholesterol acyltransferase activity, which is identical to liver carboxylesterase.
Authors: Becker A , Böttcher A , Lackner K J , Fehringer P , Notka F , Aslanidis C , Schmitz G
Published: June 2011

An enzyme with acyl coenzyme A:cholesterol acyltransferase (ACAT) activity was isolated from porcine liver, and sequences derived from trypsinized peptides indicated homology to liver carboxylesterase. By use of degenerate primers, human cDNA clones were identified, which were identical to human liver carboxylesterase. Expression of the full-length cDNA in Chinese hamster ovary (CHO) cells led to an approximately threefold increase in cellular ACAT activity. This was accompanied by an approximately 20-fold increase of cellular cholesteryl ester content. By light and electron microscopy, recombinant CHO cells contained numerous lipid droplets that were not present in control CHO cells. Expression of an antisense cDNA in HepG2 cells reduced cellular ACAT activity by 35% compared with control. To further investigate the role of the enzyme in cellular cholesterol homeostasis, regulation of the mRNA was investigated in 7-day cultured human mononuclear phagocytes (MNPs). When these cells were incubated in lipoprotein-deficient serum for 18 hours, the mRNA for ACAT/carboxylesterase was almost not detectable on Northern blots, whereas after incubation with acetylated low-density lipoproteins, a strong hybridization signal was obtained. This is evidence that the mRNA of ACAT/carboxylesterase is induced by cholesterol loading. It is concluded from the data presented that ACAT/carboxylesterase is relevant for cellular cholesterol esterification in vivo. The regulation in MNPs indicates that the enzyme is also involved in foam cell formation during early atherogenesis.
Effects of chronic administration of ethanol on platelets from rabbits with diet-induced hypercholesterolemia. Unchanged characteristics and responses to ADP but reduction of enhanced thrombin-induced, TxA2-independent platelet responses.
Authors: Latta E K , Packham M A , DaCosta S M , Rand M L
Published: June 2011

To investigate the effect on platelet function of the interaction between dietary cholesterol and moderate, chronic doses of ethanol, hypercholesterolemia was induced in rabbits by 8 weeks of administration of a chow diet with added (0.25% wt/wt) cholesterol; during the eighth week, a moderate amount of ethanol (6% in drinking water) was given. Blood alcohol levels were not detectable in ethanol-treated rabbits at the time of exsanguination. Ethanol did not affect plasma cholesterol levels or the cholesterol to phospholipid molar ratio in platelets. Platelet membrane fluidity, which decreased with cholesterol feeding, was not altered further by administration of ethanol. The overall fatty acid composition of platelet phospholipids was not affected by either cholesterol feeding or chronic ethanol intake. Responses of washed platelets stimulated with either ADP or thrombin were studied to determine whether ethanol administration modified platelet functions in hypercholesterolemia. Primary ADP-induced aggregation was not affected by cholesterol feeding or chronic ethanol intake, but thrombin-induced aggregation and secretion of [14C]serotonin from prelabeled platelets, which were enhanced by cholesterol feeding, were diminished by administration of ethanol to hypercholesterolemic rabbits. This reduction in thrombin-induced responses was also observed with aspirin-treated platelets, which cannot form thromboxane A2. Thus, chronic short-term administration of a moderate amount of ethanol inhibited the enhanced responses of platelets from rabbits with diet-induced hypercholesterolemia, via a thrombin-induced, thromboxane A2-independent pathway.
Comparative study on the effect of low-dose vitamin E and probucol on the susceptibility of LDL to oxidation and the progression of atherosclerosis in Watanabe heritable hyperlipidemic rabbits.
Authors: Kleinveld H A , Demacker P N , Stalenhoef A F
Published: June 2011

The diet of Watanabe heritable hyperlipidemic (WHHL) rabbits was supplemented with a low dose (0.025% [wt/wt]) of the antioxidant vitamin E or probucol. The effect of 6 months of treatment on the susceptibility of low-density lipoproteins (LDLs) to oxidative modification and on established atherosclerotic lesions was studied. Vitamin E administration had no effect on plasma lipid levels; probucol supplementation decreased plasma total cholesterol. Vitamin E levels in plasma and LDL increased threefold in the course of treatment with this antioxidant. Six months of treatment with vitamin E and probucol increased the lag time of conjugated-diene formation of LDL subjected to in vitro oxidation by 54% (P < .001) and 51% (P = .019), respectively. In this LDL-oxidizability assay, only vitamin E reduced the maximal rate of conjugated-diene production (-24%, P < .001). Neither vitamin E treatment nor probucol therapy reduced the amount of thiobarbituric acid-reactive substances in plasma. Vitamin E treatment reduced the specific LDL apolipoprotein B-100 fluorescence (-10%, P = .035) compared with controls. Probucol was without effect on this index of in vivo LDL oxidation. At the end of the 6-month study, the mean +/- SD percentage area of aorta covered with plaques was 58.7 +/- 10.1% in control animals, 62.7 +/- 12.0% in the probucol-treated animals, and 48.9 +/- 13.8% in the animals treated with vitamin E; these differences were not significant. This study demonstrates that at this low dosage, vitamin E is a more effective antioxidant than probucol.
Serum amyloid A protein family. Differential induction by oxidized lipids in mouse strains.
Authors: Liao F , Lusis A J , Berliner J A , Fogelman A M , Kindy M , de Beer M C , de Beer F C
Published: June 2011

During inflammation, serum amyloid A (SAA) protein increases up to 1000-fold and can become a major component of high-density lipoprotein (HDL). We have identified a new apolipoprotein molecule (SAA5) as a distinct member of the SAA family. It differs from the inflammatory isotypes (SAA1, SAA2, and SAA3) not only in structure but in the fact that it is constitutive on normal HDL where it accounts for more than 90% of total SAA. Whereas all members of the SAA family, including SAA5, responded to endotoxin administration, SAA5 contrasted with other SAAs in its resistance to induction either by a high-fat, high-cholesterol atherogenic diet or the injection of mildly oxidized LDL (MM-LDL). These data provide further evidence that the induction of inflammatory molecules by oxidized lipids is selective. In atherosclerosis-susceptible C57BL/6 mice and atherosclerosis-resistant C3H/HeJ mice, the inflammatory SAA isotypes (SAA1, SAA2, and SAA3) responded in a strain-specific manner to oxidized lipids either generated with feeding of the atherogenic diet or introduced by MM-LDL injection. We hypothesize that the constitutive SAA5 molecules on normal HDL may contribute to its normal physiological role and that the dramatic induction of the inflammatory SAA subfamily equips the particle for an altered yet related functional role appropriate to the inflammatory state.
Relation Between Cholesterol Ester Transfer Protein Activities and Lipoprotein Cholesterol in Patients With Hypercholesterolemia and Combined Hyperlipidemia
Authors: Tatò Federico , Vega Gloria Lena , Tall Alan R. , Grundy Scott M.
Published: June 2011

Abstract
Cholesterol ester transfer protein (CETP) promotes the transfer of cholesterol esters among different lipoprotein classes–high-density lipoproteins (HDL), very-low-density lipoproteins, intermediate-density lipoproteins, and low-density lipoproteins (LDL). The current study was carried out to determine whether CETP activities are correlated with lipoprotein cholesterol levels in a large number of patients having elevated LDL cholesterol and normal triglycerides (hypercholesterolemia) and elevated LDL cholesterol and high triglycerides (combined hyperlipidemia). Compared with 50 normolipidemic male patients, 113 hypercholesterolemic patients had a 42% higher mean activity of CETP, and approximately 60% of these patients had CETP activities outside the normal range. A similar elevation of CETP was observed in 47 patients with combined hyperlipidemia. Furthermore, in those with combined hyperlipidemia, CETP activities were highly correlated with LDL cholesterol, non-HDL cholesterol, and non-HDL/HDL ratios. Similar high correlations were obtained by combining normotriglyceridemic patients with and without elevated LDL cholesterol. Since patients with elevated LDL cholesterol had a significantly lower mean level of HDL cholesterol, a high CETP activity also was related to a reduced HDL cholesterol level. Our results are consistent with this concept, although they do not constitute final proof that high CETP activities contribute to elevated cholesterol concentrations and reduced HDL cholesterol levels in patients with hypercholesterolemia and in those with combined hyperlipidemia.
Gemfibrozil Enhances Platelet Activity in Patients With Combined Hyperlipoproteinemia
Authors: Bröijersén Anders , Eriksson Mats , Angelin Bo , Hjemdahl Paul
Published: June 2011

Abstract
A placebo-controlled crossover study was conducted to evaluate whether lipid-lowering with gemfibrozil (10 to 12 weeks) affects platelet function in vivo at rest and during mental stress in 21 men with combined hyperlipoproteinemia. Gemfibrozil lowered plasma triglycerides and total and VLDL cholesterol (
P
<.001 for all), whereas HDL cholesterol increased (
P
<.001). Gemfibrozil increased platelet counts by 18% (
P
<.001) and, according to filtragometry measurements, enhanced overall (means of rest and stress values) platelet aggregability in vivo (
P
=.014); this effect was more evident during mental stress (
P
=.027) than at rest (
P
=.18). Moreover, the urinary excretion of 11-dehydro-thromboxane-B
2
was 54% higher during treatment with gemfibrozil (
P
<.001), whereas the excretion of β-thromboglobulin in urine was unaltered. Plasma β-thromboglobulin tended to be slightly elevated during active treatment (
P
=.15). Mental stress increased heart rate and catecholamine levels and elevated all cholesterol fractions (
P
<.01) and plasma β-thromboglobulin (during placebo,
P
=.02), but platelet aggregability did not increase significantly. A positive correlation was found between 11-dehydro-thromboxane-B
2
excretion and LDL cholesterol levels during placebo (
r
=.62,
P
=.0057). In conclusion, gemfibrozil has beneficial effects on plasma lipoprotein levels but enhances several aspects of platelet activity in vivo and increases platelet counts. These changes might be prothrombotic and thus adverse for the hyperlipidemic patient. Primary preventive effects of gemfibrozil might be enhanced if a platelet inhibitor such as aspirin is administered with gemfibrozil.
Platelet-Derived Growth Factor Causes Sustained Depletion of Both Inositol Trisphosphate-Sensitive and Caffeine-Sensitive Intracellular Calcium Stores in Vascular Smooth Muscle Cells
Authors: Lapidot Smadar A. , Phair Robert D.
Published: June 2011

Abstract
Since the platelet-derived growth factor (PDGF)–induced increase in cellular inositol 1,4,5-trisphosphate (InsP
3
) has been found to decay to basal levels soon after the onset of PDGF exposure, it has been argued that activation of Ca
2+
release from intracellular stores must be similarly transient. The possibility remains, however, that PDGF-induced release of stored Ca
2+
is initiated and sustained by other second-messenger systems. To test the hypothesis that PDGF-BB initiates sustained Ca
2+
release from cellular stores, we performed 4-hour
45
Ca effluxes on monolayers of A7r5 vascular smooth muscle cells in small, continuously perfused chambers. Isoform PDGF-BB (5 ng/mL for 30 minutes or 30 ng/mL for 15 minutes) was added to the perfusate beginning at 30 minutes of efflux. A dose-related increase in
45
Ca release was sustained as long as PDGF-BB was present. Detailed kinetic analysis and nonlinear least-squares fitting of the experimental data revealed that (1) PDGF-BB induced sustained increases of 2.86-fold (5 ng/mL) and 6.50-fold (30 ng/mL) in the rate constant governing Ca
2+
release from intracellular stores, (2) the apparent
K
m
for this effect was 13.4±1.31 ng PDGF-BB/mL, and (3) the entire agonist-releasable Ca
2+
store (presumably sarcoplasmic reticulum) is sensitive to PDGF-BB. These data indicate that PDGF-BB causes a sustained depletion of intracellular Ca
2+
stores by means of sustained activation of Ca
2+
release and suggest that intraorganellar Ca
2+
may be one of the signals that mediates long-term smooth muscle responses to PDGF.
Oxidized LDL Induces Transcription Factor Activator Protein–1 but Inhibits Activation of Nuclear Factor–κB in Human Vascular Smooth Muscle Cells
Authors: Ares Mikko P.S. , Kallin Bengt , Eriksson Per , Nilsson Jan
Published: June 2011

Abstract
Oxidized LDL (Ox-LDL) has been implicated in the development of atherosclerotic lesions, mainly due to its enhanced uptake by macrophages and its ability to alter gene expression in arterial cells. In the present study we demonstrated that Ox-LDL activates activator protein–1 (AP-1), a transcription factor generally induced by mitogenic substances. Lysophosphatidylcholine, which is generated during oxidation of LDL, stimulated AP-1 in a dose-dependent manner. In contrast, the radical-dependent transcription factor nuclear factor–κB (NF-κB) was not activated by Ox-LDL, and at a concentration of 50 μg/mL, Ox-LDL inhibited lipopolysaccharide-induced activation of NF-κB. Oxysterols but not lysophosphatidylcholine inhibited lipopolysaccharide-induced NF-κB activation, suggesting that they may be responsible for the inhibitory effect of Ox-LDL. In conclusion, Ox-LDL has opposing effects on the activities of NF-κB and AP-1, suggesting involvement of mechanisms for transcriptional regulation that are strongly affected by lipid oxidation products.
Common Mutations in the Low-Density-Lipoprotein–Receptor Gene Causing Familial Hypercholesterolemia in the Japanese Population
Authors: Maruyama Takao , Miyake Yasuko , Tajima Shoji , Harada-Shiba Mariko , Yamamura Taku , Tsushima Motoo , Kishino Bun-ichiro , Horiguchi Yasunori , Funahashi Tohru , Matsuzawa Yuji , Yamamoto Akira
Published: June 2011

AbstractFamilial hypercholesterolemia (FH) is a common genetic disorder caused by mutations of the LDL-receptor gene. In the present study, we investigated four Japanese FH homozygotes and identified five point mutations: a splice site mutation in intron 12 (the 1845+2 T→C mutation), a missense mutation in exon 7 (the C317S mutation), a nonsense mutation in exon 17 (the K790X mutation), a missense mutation in exon 14 (the P664L mutation), and a missense mutation in exon 4 (the E119K mutation). We developed simple methods for detecting these mutations. When we examined the presence of these mutations in 24 unrelated FH homozygotes, the 1845+2 T→C mutation was found in 7 of them, and the other four mutations were unique for each proband. We also screened 120 unrelated FH heterozygotes for these mutations and found that the frequencies of the 1845+2 T→C, C317S, K790X, P664L, and E119K mutations were 13.3% (16/120), 6.7% (8/120), 6.7% (8/120), 3.3% (4/120), and 1.7% (2/120), respectively. These mutations were found in more than 30% of unrelated Japanese FH patients. By using the detection methods developed in this study, the diagnosis of more than 30% of the genetic bases of Japanese FH heterozygotes is expected.
G→A Substitution at Position −75 of the Apolipoprotein A-I Gene Promoter
Authors: Minnich Anne , DeLangavant Ghislaine , Lavigne Jacques , Roederer Ghislaine , Lussier-Cacan Suzanne , Davignon Jean
Published: June 2011

Abstract
The present study sought to resolve the contradictory evidence as to whether the G→A substitution at position −75 of the apoA-I gene promoter raises HDL cholesterol (HDL-C) levels by examining the effect of this polymorphism in French Canadians, a relatively genetically homogeneous population. Among 308 women, carriers of the A allele displayed 12% and 10% higher mean plasma HDL-C and apoA-I concentrations, respectively, than did noncarriers. Among 345 men, no effect of the A allele was noted. The frequency distribution of HDL-C levels in women carrying the A but not the G allele appeared bimodal, with one peak corresponding to the mean of the noncarriers and a second to higher HDL-C. Thus it appears that only a subset of A alleles confers high HDL-C levels. This hypothesis was supported by data from four kindreds within which some but not all A alleles segregated with hyperalphalipoproteinemia. The data suggest that the A substitution in the apoA-I gene promoter does not directly confer high HDL-C levels but may be in linkage disequilibrium with other sequence polymorphism(s) at this locus in a subset of alleles that raise HDL-C levels.
Generation of Pre-β
1
-HDL and Conversion Into α-HDL
Authors: Huang Yadong , von Eckardstein Arnold , Wu Shili , Langer Claus , Assmann Gerd
Published: June 2011

Abstract
HDL encompasses several apoA-I–containing particles that differ by size and show pre-β- or α-mobility on agarose gel electrophoresis: pre-β
1
-LpA-I, pre-β
2
-LpA-I, pre-β
3
-LpA-I, α-LpA-I
2
, and α-LpA-I
3
. The quantitatively minor subclass pre-β
1
-LpA-I serves as an initial acceptor of cell-derived cholesterol. In this study, we generated a pre-β
1
-LpA-I–like particle in vitro by the incubation of biotinylated apoA-I with cholesterol-loaded macrophages. Both native pre-β
1
-LpA-I and in vitro–generated pre-β
1
-LpA-I were indistinguishable from lipid-free apoA-I by two-dimensional nondenaturing polyacrylamide gradient gel electrophoresis but exhibited a different size upon gel filtration. In vitro–generated biotin–pre-β
1
-LpA-I took up twofold to threefold more [
3
H]cholesterol from labeled fibroblasts during a 1-minute pulse incubation than lipid-free apoA-I. The in vitro conversion of biotin–pre-β
1
-LpA-I was investigated in the presence of plasmas of healthy probands and patients with Tangier disease, with apoA-I deficiency, and with lecithin-cholesterol acyltransferase (LCAT) deficiency. Incubation of biotin–pre-β
1
-LpA-I with plasmas either from normoalphalipoproteinemic probands or from a patient with apoA-I deficiency generated a biotinylated particle with the size and electrophoretic mobility of α-LpA-I
2
. This conversion was sensitive to heating at 56°C but not to the removal of calcium. Inhibition of LCAT by dithiobisnitrobenzoic acid led to the formation of α-LpA-I
3
instead of α-LpA-I
2
. Incubation of biotin–pre-β
1
-LpA-I with the plasma of an LCAT-deficient patient also led to the generation of biotin–α-LpA-I
3
instead of α-LpA-I
2.
By contrast, incubation of biotin–pre-β
1
-LpA-I with plasma of patients with Tangier disease did not cause the disappearance of biotin–pre-β
1
-LpA-I and the formation of biotin–α-LpA-I. However, co-incubation of Tangier disease plasma or of pre-β
1
-LpA-I isolated from Tangier disease plasma with apoA-I–deficient plasma generated α-LpA-I
2
. In conclusion, our data indicate that (1) pre-β
1
-LpA-I can be formed in vitro by the interaction of free apoA-I with cholesterol-loaded macrophages, (2) both normal and apoA-I–deficient plasmas contain a factor that converts pre-β
1
-LpA-I into α-LpA-I, and (3) this factor is absent in the plasma of patients with Tangier disease.
Lipid Composition of HDL Subfractions in Dog Plasma and Lymph
Authors: Wong Laurence , Sivok Bela , Kurucz Eva , Sloop Charles H. , Roheim Paul S. , Asztalos Bela
Published: June 2011

AbstractWe report the lipid composition of dog plasma and peripheral lymph lipoproteins as separated into pre-β, α, and pre-α fractions by agarose gel electrophoresis. Plasma lipoproteins with α mobility have a composition different from that of plasma lipoproteins with pre-α mobility, having 9% versus 11% free cholesterol, 21% versus 17% cholesterol ester, 1% versus 16% triacylglycerol, and 69% versus 56% phospholipid. On the other hand, lymph α and pre-α lipoproteins have compositions that are quite similar (9% versus 7% free cholesterol, 17% versus 17% cholesterol ester, 2% versus 4% triacylglycerol, and 71% versus 71% phospholipid). The lipid compositions of plasma and lymph α lipoproteins are quite similar (9% versus 9% free cholesterol, 21% versus 17% cholesterol ester, 1% versus 2% triacylglycerol, and 70% versus 72% phospholipid). The lipid compositions of plasma and lymph pre-α lipoproteins are different (11% versus 7% free cholesterol, 17% versus 17% cholesterol ester, 16% versus 4% triacylglycerol, and 56% versus 71% phospholipid). Peripheral lymph lipoproteins with pre-β mobility contained 15% cholesterol, 13% cholesterol ester, 10% triacylglycerol, and 61% phospholipid. Compared with plasma, peripheral lymph lipoproteins are free cholesterol–enriched in all fractions. Calculated stoichiometric ratios of lipid to apoA-I indicate that pre-β lipoproteins contain one molecule of apoA-I per particle, α lipoproteins have two molecules of apoA-I per particle, and pre-α lipoproteins have four molecules of apoA-I per particle.
Level of Apolipoprotein B mRNA Has an Important Effect on the Synthesis and Secretion of Apolipoprotein B–Containing Lipoproteins
Authors: Selby Sherri L. , Yao Zemin
Published: June 2011

Abstract
The effect of apoB mRNA level on hepatic apoB production has not been studied extensively, primarily because the steady state level of apoB mRNA cannot be altered on a short-term basis. We studied the effect of vastly different apoB mRNA levels on the synthesis and secretion of apoB-containing lipoproteins using rat hepatoma (McA-RH7777) cell lines transfected with cDNA constructs encoding human apoB53 (the amino-terminal 53% of the protein; hapoB53) or apoB100 (hapoB100). Among the three hapoB53-transfected cell lines, the relative steady state levels of the hapoB53 mRNA were 10:2.5:<0.1. Correspondingly, the relative concentration of the intracellular hapoB53 protein was 8:3:1 and of the medium hapoB53 (accumulated over a period of 18 hours) was 12:4:1, which positively correlates with the hapoB53 mRNA levels. The expression level of hapoB53 did not affect the buoyant density of lipoproteins containing hapoB53 (
d
=1.06 to 1.21 g/mL) or endogenous rat apoB100 (
d
<1.06 g/mL). When cell lines containing high or intermediate hapoB53 mRNA levels were compared, there was an eightfold increase in the synthesis and a twofold increase in the secretion efficiency of hapoB53. Analysis of the synthesis and secretion of lipids revealed that in cells producing high levels of hapoB53, triglyceride synthesis (twofold) and secretion (twofold to threefold) were also increased. Furthermore, with the three hapoB100-transfected cells we also observed an increase in apoB100 synthesis (threefold), apoB100 secretion efficiency (twofold), triglyceride synthesis (fourfold to fivefold), and triglyceride secretion (fourfold to fivefold) in the cells expressing high levels of hapoB100. In all the cell lines examined, secretion efficiency of endogenous rat apoA-I was not affected by transfection. Together these data suggest that secretion of apoB-containing triglyceride-rich lipoproteins can be influenced by the level of apoB mRNA or the rate of apoB translation.