bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of the aorta of the obese Zucker rat to injury.
Authors: Haudenschild C C , Van Sickle W , Chobanian A V
Published: June 2011

The response of the thoracic aorta to balloon-catheter-induced endothelial denudation was studied in two animal models of diabetes: the obese Zucker rat and the streptozotocin-treated Wistar rat. The obese Zucker rat, an animal with a metabolic profile similar to that of noninsulin-dependent human diabetics, was characterized by excessive body weight, hyperinsulinemia, hyperlipidemia, and a mild increase in plasma glucose levels. In Zucker rats sacrificed 3 weeks after endothelial denudation, the cross-sectional areas of the fibrocellular intimal lesions were found to be approximately twice as large as those of the lean control. In all other respects, the morphology of the lesions in the obese rats, as assessed by both light and transmission electron microscopy, was similar to that of the lean control rats. In streptozotocin-treated Wistar rats, neither the cross-sectional areas nor the morphology of the intimal lesions differed from those in control rats. These results indicate that, in the obese Zucker rat, the response to aortic intimal injury is altered.
Effects of insulin exposure upon the metabolism of rat aortic media: influence of hydrostatic forces.
Authors: Capron L , Philippe M , Guilmot J L , Flessinger J N , Housset E
Published: June 2011

When added in vitro, insulin exerts little or no effect on the metabolism of arterial media. However, indirect evidence suggests that an in vivo exposure of arterial tissue to insulin stimulates its metabolism. To evaluate the possibility that hemodynamic forces existing only in vivo may account for this difference, we studied the effect of brief (9-minute) exposures to insulin of isolated rat thoracic aorta perfused in situ at low (34 mm Hg = 4.6 kPa) and high (70 mm Hg = 9.4 kPa) static pressures. After perfusion, incorporation of glucose-derived 14C into CO2 and lipids, and production of lactate by incubated aortic tissue, were measured. At low perfusion pressure, insulin did not affect the metabolism of the media but strongly stimulated all aspects of the glucose metabolism of the adventitia. At high pressure, insulin again stimulated the adventitia but now also significantly stimulated (+66%) the synthesis of glucose-derived lipids by the media; production of CO2 and lactate by the media did not increase significantly. These results indicate that insulin directly stimulates at least one pathway of glucose metabolism by the media; and that hemodynamic forces are an important factor in determining the response of aortic media to insulin.
Normalization of lipid metabolism after withdrawal from antihypertensive long-term therapy with beta blockers and diuretics.
Authors: Middeke M , Richter W O , Schwandt P , Beck B , Holzgreve H
Published: June 2011

Blood pressure and serum lipoprotein concentrations were assessed in 40 men with essential hypertension at the end of a long-term, controlled intervention study (HAPPHY) after 5.2 +/- 1.4 years of treatment with hydrochlorothiazide (n = 23) or atenolol (n = 17) and after a wash-out period. After withdrawal from antihypertensive medication, the blood pressures of patients treated with diuretics or beta blockers rose from 142/93 and 145/91 to 159/106 and 165/104 mm Hg, respectively. At the same time, low density lipoprotein cholesterol decreased by 17 and 12 mg/dl, respectively, in the diuretic and beta blocker groups (p less than 0.05). In addition, total cholesterol decreased by 16 mg/dl (p less than 0.05) in the diuretic group, whereas high density lipoprotein cholesterol increased by 8 mg/dl (p less than 0.01) and triglycerides decreased by 27 mg/dl (p less than 0.05) in the beta blocker group at the end of the wash-out period as compared to the final phase of the HAPPHY study. The data indicate the persistence of lipid changes during long-term treatment with hydrochlorothiazide and atenolol. For the first time, it was clearly demonstrated that the well-known unfavorable effects of diuretics and beta blockers on lipid metabolism are reversible after cessation of long-term therapy of several years' duration.
Association of DNA polymorphism at the apolipoprotein B gene locus with coronary heart disease and serum very low density lipoprotein levels.
Authors: Paulweber B , Friedl W , Krempler F , Humphries S E , Sandhofer F
Published: June 2011

The role of genetic variation at the 3' end of the apolipoprotein B gene locus in the development of coronary heart disease and the regulation of the serum levels of various lipoproteins was studied by using two common restriction fragment length polymorphisms detected with the enzymes Xba I and EcoR I. A group of 106 male patients with coronary heart disease and 118 matched controls of Austrian origin were investigated. The frequency of the R2 allele of the EcoR I polymorphism at cDNA position 12,669 defined by the absence of the polymorphic EcoR I cutting site was significantly higher among patients than among controls. The controls with the R2 allele had significantly higher levels of total triglycerides, very low density lipoprotein (VLDL) triglycerides, and VLDL cholesterol than did the controls without this allele. Among the patients, the R2 allele was associated with higher serum VLDL apolipoprotein B levels. The chemical composition of VLDL in individuals with different genotypes for the EcoR I polymorphism did not differ significantly. For the Xba I polymorphism at cDNA position 7673, no correlation with coronary risk could be demonstrated. Patients and controls homozygous for the X2 allele characterized by the presence of the polymorphic Xba I cutting site showed a higher total and low density lipoprotein cholesterol level than did subjects with the genotype X1X1 or X1X2. This difference, however, was not statistically significant. These findings indicate that the R2 allele of the EcoR I polymorphism is associated with the occurrence of coronary heart disease and that variation at the 3' end of the apo B gene is involved in the regulation of VLDL metabolism.
Effect of fish oil on lipoproteins, lecithin:cholesterol acyltransferase, and lipid transfer protein activity in humans.
Authors: Abbey M , Clifton P , Kestin M , Belling B , Nestel P
Published: June 2011

A group of 33 mildly hypercholesterolemic men were stratified into three groups on diets closely matched except for the polyunsaturated fatty acid supplement. The first group received 14 g/day of linoleic acid (safflower oil); the second group, 9 g of alpha-linolenic acid (linseed oil); and the third group, 3.8 g of n-3 fatty acids (fish oil). Only fish oil lowered plasma triglycerides (by 24% at 6 weeks, p less than 0.05 compared to safflower oil). Very low density lipoprotein (VLDL) apoprotein (apo) B, triglyceride, and cholesterol all fell significantly with the fish-oil diet (p less than 0.01). Low density lipoprotein (LDL) cholesterol fell by 0.18 and 0.10 mmol/l, respectively, with the safflower-oil and linseed-oil diets, but rose by 0.24 mmol/l with the fish-oil diet (p less than 0.05). There was a strong correlation between the changes in VLDL triglyceride and LDL cholesterol with the fish-oil diet (r = -0.84, p less than 0.002). High density lipoprotein (HDL) cholesterol fell slightly in all three groups (p less than 0.02 with the linseed-oil diet only). However, the apo A-I/A-II ratio rose by 5% (p less than 0.05), and the HDL2/HDL3 protein ratio increased by 28% with the fish-oil diet (p less than 0.005). Fish oil reduced the capacity for transfer of cholesteryl ester between LDL and HDL by 23% (p less than 0.02 compared to baseline), reduced plasma lecithin:cholesterol acyltransferase activity by 21% (p less than 0.05), and reduced maximal stimulated thromboxane production by 9% (p less than 0.05). Thus fish oil produced three potentially beneficial changes: significant decreases in VLDL concentration and in thromboxane production and an increase in the HDL2/HDL3 ratio. The increase in the average HDL particle size probably reflected reduced cholesteryl ester acceptor capacity within the smaller pool of VLDL, as well as the decline in lipid transfer activity in plasma involving transfer protein itself, LDL, and HDL.
Atherogenesis during low level hypercholesterolemia in the nonhuman primate. II. Fatty streak conversion to fibrous plaque.
Authors: Masuda J , Ross R
Published: June 2011

This study focuses on the formation of lesions of atherosclerosis in the aortas and iliac arteries of nonhuman primates (Macaca nemestrina) maintained on a low level hypercholesterolemic diet (plasma cholesterol 200 to 400 mg/dl) for 2, 3, or 3.5 years. Advanced lesions, or fibrous plaques, were found in all of the animals. The extent and severity of the lesions were closely related to the level and duration of hypercholesterolemia. The presence of monocyte-macrophages, T-lymphocytes, and smooth muscle cells, and the interactions of those cells that precede fibrous plaque formation in these long-term, relatively low level hypercholesterolemic monkeys were similar to those observed in previously published studies of high level hypercholesterolemia in nonhuman primates, with one principal difference: the fibrous plaques in the longer-term, low level hypercholesterolemic animals contained increased amounts of fibrous connective tissue, more smooth muscle cells, and fewer macrophages. As in the studies with high levels of hypercholesterolemia, fibrous plaques were more frequently observed in the abdominal aorta and iliac arteries than in the thoracic aorta and aortic arch. Fibrous plaques were preferentially located at the branches and bifurcations of the arteries. These anatomic sites were consistent with those that contained fatty streaks and fibrofatty lesions in the animals fed the diet for shorter periods of time. These data are compatible with the proposal that many of the fatty streaks are converted to fibrofatty lesions, some of which ultimately become converted to fibrous plaques.
Uremic levels of oxalic acid suppress replication and migration of human endothelial cells.
Authors: Levin R I , Kantoff P W , Jaffe E A
Published: June 2011

Patients with chronic renal failure who undergo hemodialysis experience accelerated atherosclerosis and premature death. Since the end-metabolite, oxalic acid, accumulates in plasma in proportion to the severity of renal failure, we studied whether sodium oxalate (0 to 300 microM) is an endothelial toxin and, therefore, might enhance atherogenesis. Exposure to uremic levels of oxalate (greater than 30 microM) for 9 to 28 days depressed endothelial cell replication by 33% to 84% (mean +/- SD, 54% +/- 15.7%, n = 17 experiments, p = 0.002). In contrast, replication of fibroblasts exposed to 200 microM oxalate for 45 days was not inhibited. The inhibitory effect of oxalate on endothelial cell replication was both dose- and time-dependent (both p less than 0.0001) and was first detected 3 to 7 days after the initial exposure to oxalate. Further, the inhibitory effect was fully reversible upon removal of oxalate, but only if exposure was limited to 5 days or less. Sodium salts of other carboxylic acids (citric, succinic, glyoxylic, and malonic; 200 microM) as well as HCl (200 microM) did not suppress endothelial cell replication. Oxalate also inhibited endothelial cell migration but had no effect on basal, thrombin-induced, or arachidonate-induced prostacyclin production by endothelial cells. Exposure of endothelial cells to sodium oxalate (200 microM) for as little as 24 hours-a time period sufficient to induce delayed, transient inhibition of replication not detectable until approximately 1 week after exposure-inhibited incorporation of 3H-leucine into protein by 40% (p = 0.009). We conclude that sodium oxalate acts as a uremic toxin, inhibiting endothelial cell replication and migration, functions which may be important for constitutive inhibition of atherosclerosis.
Species, diet, and gender differences in plasma postheparin lipolytic activities in nonhuman primates. Relationships with plasma lipids and high density lipoproteins.
Authors: Rudel L L , Star R J
Published: June 2011

Studies were done in selected groups of nonhuman primates in which the diet (low fat and high fat as either polyunsaturated or saturated fat), gender, and species (African green monkeys and cynomolgus monkeys) were varied. Large differences in plasma lipid and lipoprotein concentrations were found among these groups, providing the opportunity to examine their relationships to postheparin lipolytic activities (PHLA) including lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL). PHLA was measured in plasma drawn 20 minutes after injection of heparin (100 units/kg). The assay was done with a radioactive triglyceride emulsion, and LPL and HTGL activities were estimated after 1 M NaCl inhibition of the former. LPL activity was high in both species of monkeys, and HTGL activity was low; the ratio of HTGL/LPL was consistently less than 0.5. The mean values for LPL activity did not vary significantly among experimental groups, but significant negative correlations between LPL activity and plasma triglyceride concentration were found. Statistically significant diet, species, and gender differences in HTGL activities were found. In high-fat-fed compared to low-fat-fed animals, HTGL activities were higher, and high density lipoprotein (HDL) cholesterol concentrations and the percentages of HDL2b were also higher. African green monkeys had consistently higher HTGL activities than cynomolgus monkeys and had higher concentrations of HDL cholesterol and a greater proportion of HDL as the larger HDL2b subfraction. Significantly lower HTGL activities were found in females compared to males fed the low-fat diets, and females had a significantly greater proportion of total HDL in the HDL2b subfraction.(ABSTRACT TRUNCATED AT 250 WORDS)
Carotid artery atherosclerosis in cholesterol-fed female cynomolgus monkeys. Effects of oral contraceptive treatment, social factors, and regional adiposity.
Authors: Shively C A , Kaplan J R , Clarkson T B
Published: June 2011

Female cynomolgus monkeys, a previously established model of carotid and coronary artery atherosclerosis, were used to study the relationships between potential risk factors and carotid artery atherosclerosis. Over a 24-month treatment period, one-third of the monkeys (n = 25) were given the oral contraceptive Ovral, one-third of the monkeys (n = 26) were given the oral contraceptive Demulen, and the remaining monkeys constituted a control group (n = 26). At necropsy, the atherosclerosis extent was measured in the left and right common carotid arteries and the left and right carotid bifurcations. Plasma lipid concentrations, regional adiposity, and social status were related to carotid artery atherosclerosis extent. The relationships between regional adiposity and social status and carotid artery atherosclerosis were accounted for, at least in part, by plasma lipid concentrations. Oral contraceptives had an adverse effect on plasma cholesterol concentrations and a protective effect against carotid artery atherosclerosis after adjusting for their effect on plasma lipids. The net result of these effects was little or no change in atherosclerosis extent in the carotid arteries due to oral contraceptive treatment.
Polymorphism in 5' flanking region of human insulin gene. Relationships with atherosclerosis, lipid levels, and age in three samples from Denmark.
Authors: Tybjaerg-Hansen A , Gerdes L U , Overgaard K , Ingerslev J , Faergeman O , Nerup J
Published: June 2011

Variations in the DNA sequence flanking the 5' region of the human insulin gene (U- and L-alleles) were studied in relation to atherosclerosis, lipid levels, and age in three groups of atherosclerotic individuals and in nonatherosclerotic controls. The atherosclerotic groups comprised a postmyocardial infarction group with a mean age of 48 years, a group of individuals operated on for carotid stenosis with a mean age of 62 years, and a group of 85-year-olds with clinical coronary disease, peripheral arterial disease, or both. All 331 individuals were unrelated Caucasians of Danish ancestry. There were no significant differences (p greater than 0.05) in genotype distribution or allele frequencies between atherosclerotic and nonatherosclerotic individuals, but in the 85-year-olds, there was evidence (p less than 0.10) for a lower U-allele frequency in nonatherosclerotic women compared to atherosclerotic women. In nonatherosclerotic women, there was a significant decrease in U-allele frequency with age (60 to 85 years). This decrease does not prove conclusively, but is compatible with, the hypothesis that the U-allele predisposes to, or the L-allele protects against, atherosclerosis. The possible effect of the U-allele on the development of atherosclerosis does not seem to be mediated through conventional risk factors.
An alpha 1/beta 1-like integrin receptor on rat aortic smooth muscle cells mediates adhesion to laminin and collagen types I and IV.
Authors: Clyman R I , Turner D C , Kramer R H
Published: June 2011

Extracellular matrix receptors on vascular smooth muscle cells may enable the cells to migrate through both interstitial and basement membrane matrices during vascular remodelling after injury. Rat aortic smooth muscle cells attach to surfaces coated with fibronectin, laminin, and collagen types I and IV. Members of the beta 1 family of integrin receptors appear to mediate attachment to these extracellular matrix components. We used a monoclonal antibody, 3A3, to identify a 185/120 kD, alpha 1/beta 1-like, heterodimeric integrin receptor that mediates rat aortic smooth muscle cell adhesion to collagen types I and IV as well as to laminin. This receptor appears to be the only beta 1 integrin receptor mediating adhesion to type IV collagen. On the other hand, the smooth muscle cells have several other beta 1 integrin receptors in addition to the 185/120 kD receptor that bind to laminin- and to collagen type I-Sepharose affinity columns. By using 3A3 to inhibit only the 185/120 kD receptor, we suggest that these other receptors also can be used by rat aortic smooth muscle cells to attach to laminin and collagen type I.
Tumor necrosis factor induced release of endothelial cell lipoprotein lipase.
Authors: Saxena U , Witte L D , Goldberg I J
Published: June 2011

The major functional pool of lipoprotein lipase (LPL) that hydrolyzes triglycerides in circulating lipoproteins is located on the vascular endothelium. The macrophage-secreted cytokine tumor necrosis factor (TNF), a molecule known to affect endothelial cell functions, was used to test the hypothesis that alterations of endothelial cell metabolism regulate the binding of LPL to these cells. TNF addition induced rapid (maximum release at 45 minutes) dissociation of LPL protein and activity from its binding sites on cultured porcine aortic endothelial cells. LPL release by TNF required endothelial cell metabolic event(s) which involved cell secretion. In addition, LPL release was inhibited by pertussis toxin, suggesting the involvement of guanine nucleotide regulatory protein(s). Addition of arachidonic acid, a molecule known to be released by endothelial cells due to phospholipase A2 activation by TNF treatment, released LPL from the cell surface. Furthermore, direct modulation of cellular phospholipase A2 activity also led to changes in the release of LPL. Our studies demonstrate that alterations in the cellular metabolism of endothelial cells, for example, by TNF, may release functional pools of LPL from the vascular endothelium. This decrease in LPL on endothelial cell surfaces might be involved in the development of hypertriglyceridemia and redirection of energy flow during infections and inflammation.
Coronary atherosclerosis in the pig. Induced plaque injury and platelet response.
Authors: Reddick R L , Read M S , Brinkhous K M , Bellinger D , Nichols T , Griggs T R
Published: June 2011

The thrombogenic potential of atherosclerotic diet-induced coronary atherosclerotic plaques was investigated in normal swine and in bleeder swine with homozygous von Willebrand disease. Fourteen paired normal and bleeder swine were placed on a 1% cholesterol diet for 1 to 16 weeks. Serum cholesterol was elevated in all animals at sacrifice. Foam cell deposits developed in all major epicardial coronary arteries, and lesions progressed over time from small subendothelial foam cell deposits to fibrous cap lesions that contained foam cells, elastic fibers, collagen, degenerative material, and smooth muscle cells. Balloon catheter injury resulted in platelet deposition, largely in a monolayer or as small platelet clumps devoid of fibrin. Lipid debris was present in injured areas of the subendothelium but did not induce thrombus formation. When the injury involved the media, platelet-fibrin thrombi were formed. Lipid was not present in these thrombi. Morphometric analysis of platelet deposition on ballooned atherosclerotic vessels showed similar numbers of platelets in both phenotypes. However, the attached platelets in bleeder pigs showed significantly less spreading than did those in the normal animals. The results show that injury to intimal foam cell and mixed cellular lesions in coronary arteries of cholesterol-fed swine does not promote the development of platelet-fibrin thrombus formation. In contrast, when the injury extended to the media, mixed thrombi were formed.
Albumin and Cr-EDTA uptake by systemic arteries, veins, and pulmonary artery of rabbit.
Authors: Lever M J , Jay M T
Published: June 2011

Experiments have been performed both in vivo and in vitro to measure the steady-state uptake of labeled albumin and Cr-ethylenediaminetetraacetate by various blood vessels of the rabbit: the ascending and descending portions of the thoracic aorta, the carotid artery, the pulmonary artery, and the inferior vena cava. The in vitro experiments indicated that the wall tissues of the pulmonary artery and the vena cava have much greater distribution volumes for albumin than do the systemic arteries. This may in part explain the differences in wall tissue concentrations in vivo and, in turn, the differences between vessels in their susceptibility to atherosclerosis.
Testosterone regulates metabolism of plasma chylomicrons in rats.
Authors: Staprans I , Rapp J H , Pan X M , Ong D L , Feingold K R
Published: June 2011

Previously we demonstrated a marked sex difference in the metabolism of chylomicrons in adult rats. In males, radiolabeled chylomicrons displayed a longer dwell time on endothelial surfaces, which resulted in a decreased chylomicron uptake by the liver. The increased rate of chylomicron metabolism in females was associated with increased postheparin lipoprotein lipase activity. In the present study, we have investigated the effects of physiological doses of sex steroid hormones on the metabolism of chylomicrons and postheparin lipoprotein lipase activity. No sex differences were found in prepubertal animals. We also found no difference in chylomicron metabolism in control female, castrated female, estrogen-treated female, castrated male, and estrogen-treated male rats. However, control male, testosterone-treated male, and testosterone-treated female rats showed increased endothelial binding of chylomicrons and decreased chylomicron uptake by the liver. Postheparin lipoprotein lipase activity also was decreased by testosterone administration. In parallel with the alterations in chylomicron metabolism, serum high density lipoprotein levels in male rats decreased with testosterone administration. These results indicate that the differences in chylomicron metabolism, postheparin lipoprotein lipase activities, and serum high density lipoprotein levels observed between male and female rats are due to testosterone.
Isolation and characterization of several plasma apolipoproteins of common marmoset monkey.
Authors: Crook D , Weisgraber K H , Rall S C , Mahley R W
Published: June 2011

To explore the potential of the common marmoset monkey (Callithrix jacchus) as a model for human plasma lipoprotein metabolism, several marmoset apolipoproteins were isolated and characterized in this study. Based on several properties, including molecular weight, amino acid composition, and sequence, the marmoset apolipoproteins are strikingly similar to human apolipoprotein (apo) A-I, A-II, C-III, and A-IV. The first 54 residues of marmoset apo A-I showed 87% sequence identity with the corresponding region of human apo A-I. Amino-terminal sequence analysis of a minor basic apo A-I isoform revealed that it contained an amino-terminal hexapeptide extension (Arg-His-Phe-Gln-Gln-) identical to that found in human proapo A-I. Like apo A-II in most nonhuman primates, marmoset apo-A-II differed from human apo A-II in that it did not contain cysteine and therefore existed as a monomer. The complete amino acid sequence of marmoset apo A-II was deduced. The protein contains 77 amino acids, as does human apo A-II, and showed an 82% identity with its human equivalent. In both species, apo C-III and E had similar amino-terminal sequences and amino acid compositions. Like human apo E, marmoset apo E contained minor sialylated isoforms. However, unlike human apo C-III, no sialyated isoforms of marmoset apo C-III were observed. In addition, the marmoset possessed an apolipoprotein whose molecular weight and amino acid composition were similar to those of human apo A-IV. The close structural similarities between corresponding marmoset and human apolipoproteins indicate that the marmoset monkey will be useful as a model for human lipoprotein metabolism.
Hemodynamics and low density lipoprotein metabolism. Rates of low density lipoprotein incorporation and degradation along medial and lateral walls of the rabbit aorto-iliac bifurcation.
Authors: Berceli S A , Warty V S , Sheppeck R A , Mandarino W A , Tanksale S K , Borovetz H S
Published: June 2011

We have investigated whether arterial wall low density lipoprotein (LDL) metabolism in areas of disturbed flow differs from the metabolism in adjacent regions of undisturbed flow. Using the rabbit aorto-iliac bifurcation as a model, we examined the rates of LDL incorporation and catabolism in vivo and correlated them to the arterial flow patterns in these regions. The trapped ligand method was used to quantitate the rates of LDL incorporation and degradation over a 20-hour period in three hemodynamic zones of the daughter iliac branch: 1) a region of flow separation where the shearing forces are elevated along the medial wall and reduced along the lateral wall, 2) a transition region where the flow patterns begin to approach the fully established situation, and 3) a unidirectional flow region with symmetric fluid shearing forces along the medial and lateral walls. Our results indicate an elevated rate of LDL incorporation into the lateral versus the medial wall in the proximal zone of flow separation (5.2 +/- 0.8 nl/mg/hr vs. 3.7 +/- 0.5 nl/mg/hr, p less than 0.01). A similar elevation in the degradation rate of the lateral over the medial wall of this most proximal zone was also observed (2.1 +/- 0.4 vs. 1.4 +/- 0.2, p less than 0.05). No such differences were observed regarding LDL incorporation and degradation in the transitional or unidirectional hemodynamic zones. These results suggest that modifications in arterial wall LDL incorporation and catabolism are induced by hemodynamic forces. The implications of these findings for the formation of the atherosclerotic lesion are discussed.
Inhibition of coronary artery atherosclerosis by 17-beta estradiol in ovariectomized monkeys. Lack of an effect of added progesterone.
Authors: Adams M R , Kaplan J R , Manuck S B , Koritnik D R , Parks J S , Wolfe M S , Clarkson T B
Published: June 2011

Although controversy continues, the preponderance of evidence indicates that estrogen replacement therapy favorably influences the risk of coronary heart disease in postmenopausal women. It remains uncertain how this effect is mediated and whether the cyclic addition of a progestin may influence adversely an estrogen-related cardioprotective effect. We investigated the influence of sex hormone replacement therapy on diet-induced coronary artery atherosclerosis in estrogen-deficient (ovariectomized) adult female cynomolgus monkeys. Monkeys were assigned randomly to one of three treatment groups: 1) no hormone replacement (n = 17), 2) continuously administered 17-beta estradiol plus cyclically administered progesterone (n = 20), and 3) continuously administered 17-beta estradiol (n = 18). The physiologic patterns of plasma estradiol and progesterone concentrations were maintained by administering the hormones in sustained-release subcutaneous Silastic implants. The experiment lasted 30 months. At necropsy, coronary artery atherosclerosis was inhibited similarly (reduced by approximately one-half) in animals in both hormone replacement groups (p less than or equal to 0.05). Antiatherogenic effects of hormone replacement were independent of variation in total plasma cholesterol, lipoprotein cholesterol, apoprotein A-1 and B concentrations, high density lipoprotein subfraction heterogeneity, and low density lipoprotein molecular weight. We conclude that physiologic estrogen replacement therapy with or without added progesterone inhibits atherosclerosis progression in ovariectomized monkeys. This may explain why estrogen replacement therapy results in reduced risk of coronary heart disease in postmenopausal women.
Vascular responses to endothelin-1 in atherosclerotic primates.
Authors: Lopez J A , Armstrong M L , Piegors D J , Heistad D D
Published: June 2011

Endothelin-1 (ET-1) is a vasoactive peptide that is released by endothelial cells. This study was performed to determine whether vascular responses to ET-1 are altered by atherosclerosis. ET-1 (1 or 10 nmol) was injected intra-arterially into the perfused hind limb of normal cynomolgus monkeys and monkeys fed an atherogenic diet for 19 months. We calculated the resistance of the total limb and large arteries and estimated the resistance of the small vessels. The major finding was that ET-1 had minimal effects on large arteries in normal monkeys but produced pronounced constriction of large arteries in atherosclerotic monkeys. In both groups, ET-1 produced dilatation of small vessels at 1 nmol and constriction at 10 nmol. Indomethacin (6 mg/kg intravenously) did not affect the responses to ET-1 in normal or atherosclerotic monkeys. In summary, the major finding is that the constrictor responses of large arteries to ET-1 are potentiated by atherosclerosis.
Myosin isoform expression and smooth muscle cell heterogeneity in normal and atherosclerotic rabbit aorta.
Authors: Zanellato A M , Borrione A C , Tonello M , Scannapieco G , Pauletto P , Sartore S
Published: June 2011

Two monoclonal antimyosin antibodies, Western blotting experiments, and immunofluorescence procedures were used to investigate myosin isoform expression in normal and atherosclerotic aortas of adult rabbits. The SM-E7 antibody reacted with the two myosin heavy chain (MHC) isoforms of smooth muscle (SM) type (SM-MHC-1 and SM-MHC-2) expressed in the adult rabbit aorta. The NM-G2 antibody recognized an epitope shared by the nonmuscle (NM) myosin heavy chains (NM-MHC) present in fibroblasts, macrophages, lymphocytes, and platelets. Two smooth muscle cell (SMC) populations were identified in the medial layer of normal adult aorta, namely cells that contained SM myosin exclusively and cells that showed the coexistence of SM and NM myosin isoforms. The size of the cell population with double myosin isoform content increased markedly during experimental atherogenesis and represented by far the predominant SMC phenotype in the atherosclerotic plaque. Western blotting analysis performed on crude extracts from the atherosclerotic plaque showed the presence of SM-MHC-1 and NM-MHC isoforms in this tissue. Co-expression of SM and NM myosin at the molecular and the cellular level were found in aortic tissue during the early stages of development. These results indicate that in experimental atherosclerosis, the accumulation in the plaque of SMC with an "immature" pattern of myosin isoform expression is accompanied by similar modifications in the differentiation pattern of SMC of the underlying media.
Reduction of endothelial microfilament bundles in the low-shear region of the canine aorta. Association with intimal plaque formation in hypercholesterolemia.
Authors: Uematsu M , Kitabatake A , Tanouchi J , Doi Y , Masuyama T , Fujii K , Yoshida Y , Ito H , Ishihara K , Hori M
Published: June 2011

To interrelate in vivo wall shear stress, endothelial microfilament bundle formation, and atherosclerosis localization, we used a mild abdominal aortic stenosis in 11 beagles to produce a range of wall shear stresses above and below the constriction. Six of the beagles were fed standard animal chow supplemented with 5% cholesterol and 10% coconut oil. Wall shear stresses, endothelial microfilament bundles, and intimal plaque localization were assessed along the stenosed aorta. Shear stress was determined in vivo from the near-wall velocity profiles with a 20-MHz, 80-channel, multigate Doppler velocimeter. Content of the microfilament bundles was quantified by planimetry of transmission electron photomicrographs. After 6 weeks, mean shear stress was higher immediately upstream from the throat of the stenosis than at the proximal site (46.1 +/- 7.3 dynes/cm2 versus 24.0 +/- 6.2 dynes/mc2, p less than 0.001) and was significantly lower immediately distal to the stenosis than at the proximal site (9.4 +/- 0.3 dynes/cm2, p less than 0.01). The microfilament bundle content increased immediately upstream from the throat of the stenosis and decreased immediately distal to the stenosis compared with the proximal site in both normocholesterolemic and hypercholesterolemic fat-fed beagles. Intimal plaques formed exclusively immediately distal to the stenosis in the hypercholesterolemic beagles. These findings suggest that a low shear-stress environment attenuates endothelial microfilament bundle formation, thus leading to a predilection for the initiation of atherosclerosis in atherogenic conditions such as hypercholesterolemia.
The antioxidant butylated hydroxytoluene protects against atherosclerosis.
Authors: Björkhem I , Henriksson-Freyschuss A , Breuer O , Diczfalusy U , Berglund L , Henriksson P
Published: June 2011

Rabbits fed a 1% cholesterol diet with or without the antioxidant butylated hydroxytoluene (BHT) developed typical atherosclerotic lesions. The addition of BHT gave higher levels of total cholesterol (+40%), triglycerides (+250%), low density lipoprotein (LDL), and very low density lipoprotein (VLDL) in plasma. Despite the lower plasma lipid levels, the degree of atherosclerosis of the aortic surface was considerably higher in rabbits fed cholesterol than in the group treated with cholesterol and BHT. The mean atherosclerotic involvement was 18.6 +/- 4.4% in the former group and 5.9 +/- 1.7% in the latter group (p = 0.02). In all animals, there was a high correlation between the area of the arterial lesion and cholesterol content (r = 0.96). Serum levels of cholesterol autooxidation products (7-ketocholesterol and cholesterol 5 alpha,6 alpha-epoxide) were lower in the group of rabbits treated with BHT (p less than 0.005). Serum levels of vitamin E were slightly higher in the BHT group. There was no significant difference in the clearance of beta-VLDL between the two treatment groups after using either beta-VLDL from cholesterol-fed animals or beta-VLDL from BHT-fed animals. The results are in accord with the contention that oxidative modification of lipoproteins is important for the development of atherosclerosis and that antioxidants may have a protective effect. At present, however, other explanations cannot be completely excluded, for example, effects of antioxidants on immunologic factors or monocyte adhesion.
Genetic variation at the plasminogen activator inhibitor-1 locus is associated with altered levels of plasma plasminogen activator inhibitor-1 activity.
Authors: Dawson S , Hamsten A , Wiman B , Henney A , Humphries S
Published: June 2011

Plasminogen activator inhibitor-1 (PAI-1), a rapid inhibitor of tissue-type plasminogen activator, has been shown to be an independent risk factor for recurrent myocardial infarction (MI) at a young age. To investigate whether genetic variation in the PAI-1 gene is affecting plasma PAI-1 levels, a sample of 145 patients with an MI before the age of 45 years was genotyped for two polymorphisms at the PAI-1 locus, together with a sample of 95 healthy individuals of a similar age. All individuals were measured for plasma PAI-1 levels as well as for other fibrinolytic and metabolic risk indicators. A HindIII restriction fragment length polymorphism (RFLP) was used in this study in conjunction with a previously unreported eight-allele dinucleotide repeat polymorphism at the PAI-1 locus. The dinucleotide repeat polymorphism and HindIII RFLP were in strong linkage disequilibrium. There was no difference in the frequency of alleles of either polymorphism between patient and control groups. However, the smaller dinucleotide repeat alleles were significantly associated (p = 0.03) with higher plasma PAI-1 levels in the patient sample. This association was also apparent in the control sample but not at significant levels. Differences in regression coefficients for the effect of triglycerides on plasma PAI-1 levels suggest that triglyceride regulation of PAI-1 is genotype specific. Our data suggest that genetic variation at this locus contributes to between-individual differences in the level of plasma PAI-1, which is important in fibrinolysis and the pathogenesis of MI.
Autoantibodies against modified low density lipoprotein. Nonlipid factor of blood plasma that stimulates foam cell formation.
Authors: Orekhov A N , Tertov V V , Kabakov A E , Adamova IYu  , Pokrovsky S N , Smirnov V N
Published: June 2011

The blood serum of patients with coronary atherosclerosis possesses an ability to induce the accumulation of cellular lipids in primary cultures of human aortic intimal cells. Factors responsible for this property of the atherosclerotic patients' sera are represented by modified (desialylated) low density lipoprotein (LDL) and a nonlipid factor interacting with LDL. It was assumed that the nonlipid factor was antibodies against LDL. Total immunoglobulin G (IgG) fraction was isolated from the sera of atherosclerotic patients, and IgGs interacting with LDL (anti-LDL) were then purified by affinity chromatography on a sorbent with immobilized LDL. From the sera of patients, a 30-fold greater amount of anti-LDL has been isolated than from the sera of healthy donors. The affinity constant of anti-LDL to the lipoprotein obtained from the blood of healthy donors was 2 x 10(7) M-1. The affinity of anti-LDL to the lipoprotein from the blood of atherosclerotic patients, as well as to LDL desialylated in vitro with neuraminidase, was much higher. Anti-LDL increased the uptake of LDL by cultured aortic cells by approximately 2.5-fold and substantially increased intracellular lipid accumulation. The obtained data suggest that autoantibodies against LDL are an essential factor of blood plasma responsible for its atherogenic potential.
Reduction of transmural 125I-albumin concentration in rat aortic media by chronic hypertension.
Authors: Belmin J , Michel J B , Curmi P A , Salzmann J L , Juan L , Tedgui A
Published: June 2011

Relative 125I-albumin concentration was measured in vivo in the aortic media of sham-operated (n = 10) and hypertensive (two-kidney, one clip) rats, untreated (n = 8) or treated (n = 10) by an angiotensin converting enzyme inhibitor (CEI, Trandolapril). Blood pressure was acutely lowered to a normal level at the time of the experiment in hypertensive rats (n = 7) to separate the direct effect of increased pressure from the effect of pressure-induced structural changes. Relative tissue concentration profiles of labeled albumin across the media were obtained using a serial frozen-sectioning technique. In hypertensive rats, the mean medial albumin concentration decreased by 35% in the ascending arch and 32% in the descending arch (p less than 0.01). When blood pressure was acutely lowered in hypertensive animals, this value decreased further by 56% in the ascending arch, 48% in the descending arch (p less than 0.01), and 22% in the thoracic aorta (p less than 0.05) as compared with controls. The medial thickness in hypertensive rats was significantly increased (more in the ascending arch than in the rest of the aorta). Four-week CEI treatment reversed hypertension and medial thickening, but the mean medial albumin concentration remained significantly lower in the arch (by 36% in the ascending part and 40% in the descending part, p less than 0.01). The collagen content in the thoracic aorta was significantly increased in hypertensive rats (by 40%, p less than 0.01) and remained increased (by 29%, p less than 0.01) after CEI treatment. These results suggested that the hypertension-induced structural changes might reduce the medial distribution volume for albumin, whereas elevated blood pressure per se tended to enhance albumin concentration within the media. However, the net result of chronic hypertension was a reduction of the mean medial albumin concentration. The aortic arch appeared to be more affected than the rest of the aorta. Fiber content, more than medial thickness, might be responsible for the observed differences in albumin concentration. Lowering of blood pressure seemed to be insufficient to restore normal albumin concentration profiles and perhaps those of other macromolecules. This finding may be relevant in evaluating some of the complications associated with hypertension.
Identification of the base substitution responsible for the Ag(x/y) polymorphism of apolipoprotein B-100.
Authors: Wu M J , Bütler E , Bütler R , Schumaker V N
Published: June 2011

The identification of the base substitution responsible for Ag(x/y) completes the description of the antigen group polymorphisms associated with the apolipoprotein B polypeptide. Surprisingly, all five antigen group polymorphisms alter restriction endonuclease cleavage sites and have associated restriction fragment length polymorphisms, thereby providing a convenient alternative for antigen group phenotyping.
n-3 fatty acids and leukocyte chemotaxis. Effects in hyperlipidemia and dose-response studies in healthy men.
Authors: Schmidt E B , Pedersen J O , Varming K , Ernst E , Jersild C , Grunnet N , Dyerberg J
Published: June 2011

Dietary supplementation with n-3 polyunsaturated fatty acids (n-3 PUFAs) has been shown to inhibit neutrophil and monocyte chemotaxis in healthy subjects and, with respect to neutrophils, also in various patient groups. We studied the effect of dietary supplementation with n-3 PUFAs on monocyte and neutrophil chemotaxis in patients with hyperlipidemia. Chemotaxis was investigated with the under-agarose assay, using autologous serum and N-formyl-methionyl-leucyl-phenylalanine as chemoattractants. The patients were examined before and after 6 weeks of supplementation with 6 g n-3 PUFAs daily. Monocyte chemotaxis was reduced after n-3 PUFA supplementation in type IIa patients but was unaffected in patients with type IV hyperlipidemia. Furthermore, monocyte chemotaxis was increased in untreated type IIa patients compared with normocholesterolemic controls. We also studied the dose-response effects of n-3 PUFAs on monocyte and neutrophil chemotaxis in healthy men given 1.3, 4, and 9 g n-3 PUFAs daily for 6-week periods. Monocyte and neutrophil chemotaxis was reduced after n-3 PUFA supplements in a dose-dependent fashion, with the majority of the effect observed after the low dose. These results lend support to the notion of an antiatherosclerotic effect of n-3 PUFAs and may provide an explanation for the hitherto-unexplained effect of low doses of n-3 PUFAs in coronary heart disease.
Varying susceptibility of different low density lipoproteins to oxidative modification.
Authors: Jialal I , Freeman D A , Grundy S M
Published: June 2011

The oxidative modification of low density lipoprotein (LDL) may provide a crucial link between plasma LDL and the atherosclerotic lesion. The studies presented herein define time-dependent modifications of LDL constituents caused by CuSO4-catalyzed oxidation. Measurement of the cholesterol content of oxidized LDL by the cholesterol esterase-oxidase assay was found to be inaccurate. The enzymatic assay detected oxysterols as well as cholesterol and thus substantially overestimated the actual cholesterol content. Alteration of electrophoretic mobility and conversion of sterols into oxysterols increased in a parallel, time-dependent manner. Lipid peroxidation, judged by the thiobarbituric acid-reacting substances assay, increased early to maximal values but was not linearly related to either electrophoretic mobility or to oxysterol formation. Neither electrophoretic mobility nor oxysterol formation varied much between repeated oxidative modifications of any given LDL preparation but varied markedly among LDLs from different normolipidemic individuals, suggesting that LDL particles contain some factor conferring susceptibility or resistance to oxidation. Indeed, LDL preparations from different individuals have varying susceptibilities to oxidative modification as evidenced by the three indexes used. The major oxysterol generated was 7-ketocholesterol. Macrophage modification of LDL also resulted in the generation of oxysterols. Thus, measurement of oxysterols may afford an additional index of the oxidative modification of LDL. Since incubation of macrophages with oxidized LDL but not native LDL resulted in the accumulation of oxysterols, this could account for some of the toxic and metabolic effects of oxidized LDL on cells.
Chlamydia pneumoniae strain TWAR antibody and angiographically demonstrated coronary artery disease.
Authors: Thom D H , Wang S P , Grayston J T , Siscovick D S , Stewart D K , Kronmal R A , Weiss N S
Published: June 2011

A recent case-control study from Finland reported a strong association between high antibody titers to Chlamydia pneumoniae, strain TWAR, and both chronic coronary heart disease and acute myocardial infarction. The current case-control study investigated the relation between C. pneumoniae immunoglobulin G antibody titers and angiographically diagnosed coronary artery disease. Cases (n = 461) were angiography patients with at least one coronary artery lesion occupying at least 50% of the luminal diameter. Controls (n = 95) were angiography patients with no demonstrable coronary artery disease. After standardization for age and gender, the geometric mean antibody titer was higher for cases than for controls (30.0 versus 24.0, p = 0.04). The estimated risk of coronary artery disease, adjusted for age and gender, was greater among subjects with high (greater than or equal to 1:64) antibody titers than among subjects with low (less than or equal to 1:8) antibody titers (relative risk, 2.0; 95% confidence interval, 1.0-4.0). The risk associated with a high antibody titer was particularly great for coronary artery disease with five or more lesions (relative risk, 2.8; 95% confidence interval, 1.2-7.0). The results of this cross-sectional study support an association between infection with C. pneumoniae and coronary artery disease.