bluuebunny/crossref_metadata_2025 huggingface dataset:
Antioxidative and Antiatherosclerotic Effects of Human Apolipoprotein A-IV in Apolipoprotein E–Deficient Mice
Authors: Ostos Maria A. , Conconi Mariangela , Vergnes Laurent , Baroukh Nadine , Ribalta Josep , Girona Josefa , Caillaud Jean-Michel , Ochoa Alberto , Zakin Mario M.
Published: June 2011

Abstract
—Mice expressing human apolipoprotein A-IV (apoA-IV) mainly in the intestine were obtained in an apolipoprotein E–deficient (apoE
0
) background (apoA-IV/E
0
mice). Quantification of aortic lesions and plasma lipid determination showed that compared with their control apoE
0
counterparts, the apoA-IV/E
0
mice are protected against atherosclerosis without an increase in HDL cholesterol. Because oxidized lipoproteins play an important role in atherogenesis, we tested whether the protection observed in these animals is accompanied by an in vivo reduction of the oxidation parameters. The lag time in the formation of conjugated dienes during copper-mediated oxidation, the aggregation state of LDL, and the presence of anti–oxidized LDL antibodies were measured. The presence of oxidized proteins in tissues and the presence of oxidation-specific epitopes in heart sections of atherosclerotic lesions were also analyzed. Except for lag time, the results showed that the oxidation parameters were reduced in the apoA-IV/E
0
mice compared with the apoE
0
mice. This suggests that human apoA-IV acts in vivo as an antioxidant. In addition, human apoA-IV accumulation was detected in the atherosclerotic lesions of apoA-IV/E
0
mice, suggesting that apoA-IV may inhibit oxidative damage to local tissues, thus decreasing the progression of atherosclerosis.
Plasma Acylation Stimulating Protein Concentration and Subcutaneous Adipose Tissue C3 mRNA Expression in Nondiabetic and Type 2 Diabetic Men
Authors: Koistinen Heikki A. , Vidal Hubert , Karonen Sirkka-Liisa , Dusserre Eric , Vallier Paulette , Koivisto Veikko A. , Ebeling Pertti
Published: June 2011

Abstract
—We studied the effect of an oral fat load on plasma acylation stimulating protein (ASP) concentrations in 9 lean healthy (age 59±2 years, body mass index [BMI] 23.2±0.4 kg/m
2
; both mean±SEM), 9 obese nondiabetic (58±2 years, BMI 29.4±0.5 kg/m
2
), and 12 type 2 diabetic (60±2 years, BMI 29.6±1.0 kg/m
2
) men. Because ASP is a cleavage product of complement protein C3 (C3adesArg) and its secretion is regulated by insulin, we also examined the subcutaneous adipose tissue expression of C3 mRNA before and after a 240-minute euglycemic hyperinsulinemic clamp in a subgroup of these men. Plasma ASP concentration and adipose tissue C3 mRNA expression were higher in the obese groups than in the lean men. Plasma ASP concentration did not change significantly after the fat load. Fasting plasma ASP concentration and C3 mRNA expression were correlated negatively with insulin sensitivity and positively with the magnitude of postprandial lipemia in nondiabetic but not in type 2 diabetic men. The expression of C3 mRNA was not regulated by insulin. These data suggest that ASP is associated with whole-body glucose and lipid metabolism in nondiabetic individuals, whereas metabolic disturbances in diabetes may overcome the regulatory role of ASP in lipid and glucose metabolism.
Prorenin Accumulation and Activation in Human Endothelial Cells
Authors: van den Eijnden Mark M. E. D. , Saris Jasper J. , de Bruin René J. A. , de Wit Elly , Sluiter Wim , Reudelhuber Timothy L. , Schalekamp Maarten A. D. H. , Derkx Frans H. M. , Danser A. H. Jan
Published: June 2011

Abstract
—ACE inhibitors improve endothelial dysfunction, possibly by blocking endothelial angiotensin production. Prorenin, through its binding and activation by endothelial mannose 6-phosphate (M6P) receptors, may contribute to this production. Here, we investigated this possibility as well as prorenin activation kinetics, the nature of the prorenin-activating enzyme, and M6P receptor–independent prorenin binding. Human umbilical vein endothelial cells (HUVECs) were incubated with wild-type prorenin, K/A-2 prorenin (in which Lys42 is mutated to Ala, thereby preventing cleavage by known proteases), M6P-free prorenin, and nonglycosylated prorenin, with or without M6P, protease inhibitors, or angiotensinogen. HUVECs bound only M6P-containing prorenin (
K
d
0.9±0.1 nmol/L, maximum number of binding sites [B
max
] 1010±50 receptors/cell). At 37°C, because of M6P receptor recycling, the amount of prorenin internalized via M6P receptors was >25 times B
max
. Inside the cells, wild-type and K/A-2 prorenin were proteolytically activated to renin. Renin was subsequently degraded. Protease inhibitors interfered with the latter but not with prorenin activation, thereby indicating that the activating enzyme is different from any of the known prorenin-activating enzymes. Incubation with angiotensinogen did not lead to endothelial angiotensin generation, inasmuch as HUVECs were unable to internalize angiotensinogen. Most likely, therefore, in the absence of angiotensinogen synthesis or endocytosis, M6P receptor–mediated prorenin internalization by endothelial cells represents prorenin clearance.
Function of GATA Transcription Factors in Induction of Endothelial Vascular Cell Adhesion Molecule-1 by Tumor Necrosis Factor-α
Authors: Umetani Michihisa , Mataki Chikage , Minegishi Naoko , Yamamoto Masayuki , Hamakubo Takao , Kodama Tatsuhiko
Published: June 2011

Abstract
—Endothelial vascular cell adhesion molecule-1 (VCAM-1) is expressed in response to cytokine stimulation and plays a critical role in inflammatory reactions. Previously, we developed a novel VCAM-1 inhibitor that acts through a mechanism independent of nuclear factor-κB activity. It suppresses the binding activity of GATA proteins in cytokine-stimulated endothelial cells, which may be related to the anti–VCAM-1 induction effect of this drug. In this study, we investigated the role of GATA proteins in the induction of VCAM-1 by tumor necrosis factor-α (TNF-α) in human endothelial cells. The mRNA expression of GATA-6 was increased, whereas GATA-3 mRNA was decreased by TNF-α stimulation. Electrophoretic mobility shift assay showed that TNF-α stimulation increased the DNA binding of GATA-6 but decreased that of GATA-3. Experiments using protein overexpression or antisense oligonucleotides revealed that GATA-6 potently acts as a positive regulator of VCAM-1 gene transcription. In contrast, overexpression of GATA-3 was able to suppress TNF-α–induced VCAM-1 expression. Our results provide evidence of the importance of GATA proteins in the induction of VCAM-1 by TNF-α in vascular endothelial cells. The switch from GATA-3 to GATA-6 is taken to be an important transcriptional control event in TNF-α induction of VCAM-1.
Oxidized LDL Modulates Bax/Bcl-2 Through the Lectinlike Ox-LDL Receptor-1 in Vascular Smooth Muscle Cells
Authors: Kataoka Hiroharu , Kume Noriaki , Miyamoto Susumu , Minami Manabu , Morimoto Masafumi , Hayashida Kazutaka , Hashimoto Nobuo , Kita Toru
Published: June 2011

Abstract
—Oxidized low density lipoprotein (Ox-LDL) induces apoptosis in vascular smooth muscle cells (VSMCs), which may increase atherosclerotic plaque instability. In this study, we examined the molecular mechanisms causing the Ox-LDL–induced apoptosis in VSMCs, especially focusing on the involvement of Bax/Bcl-2 and the lectinlike Ox-LDL receptor-1 (LOX-1). In cultured bovine aortic smooth muscle cells (BASMCs), Ox-LDL at high concentrations (>60 μg/mL) induced cell death as demonstrated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. DNA fragmentation was increased in BASMCs treated with high concentrations of Ox-LDL, indicating that the Ox-LDL–induced cell death in VSMCs was apoptosis. Ox-LDL upregulated LOX-1 expression through phosphorylation of extracellular signal–regulated kinase in BASMCs, and a neutralizing anti–LOX-1 monoclonal antibody, which can block LOX-1–mediated cellular uptake of Ox-LDL, prevented the Ox-LDL–induced apoptosis in BASMCs. This antibody also suppressed the increase in the Bax to Bcl-2 ratio induced by Ox-LDL in BASMCs. Furthermore, LOX-1 expression was well colocalized with Bax expression in the rupture-prone shoulder areas of human atherosclerotic plaques in vivo. LOX-1 may play an important role in Ox-LDL–induced apoptosis in VSMCs by modulating the Bax to Bcl-2 ratio. These molecular mechanisms may be involved in destabilization and rupture of atherosclerotic plaques.
Determinants of Lipid Level Variability in French-Canadian Children With Familial Hypercholesterolemia
Authors: Lambert Marie , Assouline Linda , Feoli-Fonseca Juan Carlos , Brun Nathalie , Delvin Edgard E. , Lévy Emile
Published: June 2011

Abstract
—The wide variability in the biochemical expression of familial hypercholesterolemia (FH) is only partly explained by mutational heterogeneity in the low density lipoprotein receptor (LDLR) gene. In the current study, we measured this biochemical variability in a group of children heterozygous for the >15-kb LDLR gene deletion (n=67) and examined the contribution of apolipoprotein (apo) E and B allelic variations to this phenotypic variability. Variances of total cholesterol (TC), LDL-C, and apoB concentrations and of the ratio of TC to high density lipoprotein cholesterol (HDL-C) were increased in FH subjects compared with controls. However, after taking the means into account, the coefficients of variation showed that the variability of LDL-C and apoB concentrations was smaller for FH than for controls and that the variability of TC and of the ratio TC to HDL-C was similar between both groups. The ε2/3 genotype was associated with lower mean TC, LDL-C, and apoB concentrations in FH. The magnitude of this effect was smaller in controls than in FH. Indeed, the percentages of total variance of TC, LDL-C, and apoB attributable to the apoE locus were 19.9%, 18.1%, and 11.8%, respectively, in FH cases and 5.9%, 7.4%, and 6.0%, respectively, in controls. We did not detect any effect of the apoB insertion/deletion polymorphism on lipid traits in FH children. However, in controls, we observed a strong interaction between apoE and apoB genotypes on apoB concentrations and on TC to HDL-C ratios. Our study reemphasizes the important role of apoE in lipid metabolism and illustrates that the effects of allelic variations on lipid traits are context dependent.
High-Fat, High-Cholesterol Diet Increases the Incidence of Gastritis in LDL Receptor–Negative Mice
Authors: Laurila Aino , Cole Sheri P. , Merat Shiva , Obonyo Marygorret , Palinski Wulf , Fierer Joshua , Witztum Joseph L.
Published: June 2011

Abstract
—Transgenic and knockout mice are widely used as models for atherogenesis studies. While developing a
Helicobacter
infection model in LDL receptor–negative (LDLR
−/−
) mice, we noticed that mice fed a high-fat, high-cholesterol diet often contracted gastritis independent of infection. To further investigate this finding, we studied 27 male and 18 female LDLR
−/−
mice fed high-fat, 1% or 1.25% cholesterol diets for 3 to 4 months. The extent of atherosclerosis was morphometrically analyzed in the whole aorta, and the degree of gastric inflammation was scored histologically in hematoxylin-eosin–stained stomach sections. The autoantibody titers to epitopes of oxidized LDL were also measured. Mice fed high-fat, high-cholesterol diets had a significantly higher incidence of gastritis than mice fed normal chow, 62% versus 5%, respectively (
P
<0.0001). This effect was specific for LDLR
−/−
mice, because no difference in gastritis was found in wild-type mice fed either diet. Animals with gastritis showed slightly more atherosclerosis than animals without gastritis: 16.3±6.4% versus 12.8±3.4% in males and 9.4±3.5% versus 6.5±3.3% in females. Cholesterol-fed mice also had significantly higher IgG autoantibody titers against modified LDL than normal chow–fed animals, but no difference was seen between the gastritis and nongastritis groups. We conclude that the standard high-fat, high-cholesterol diet commonly used in many murine models to induce atherosclerosis increased the incidence of gastritis significantly in LDLR
−/−
mice.
Characterization of monoclonal antibodies against human low density lipoprotein.
Authors: Milne R W , Theolis R , Verdery R B , Marcel Y L
Published: June 2011

Seven monoclonal antibodies against human low density lipoprotein (LDL) have been characterized as to their specificity and ability to interfere with the LDL pathway in cultured human fibroblasts. The immunoreactivity with LDL of two of the antibodies (2D8 and 4G3) was particularly sensitive to modification of lysine and arginine residues in LDL. Cotitration experiments indicated that the antibodies 3A8 and 3A10 may react with the same determinant and that five antibodies (5E11, 3A8, 3A10, 4G3 and 3F5) recognized determinants that were grouped in the same region of the molecule. The two other antibodies (1D1 and 2D8) reacted with determinants distant from this region. When tested in molar excess relative to LDL, Fab fragments of 5E11, 3A8, 3A10, 4G3 and 3F5 (but not 1D1 or 2D8) were capable of blocking the binding of 125I-LDL to the LDL receptor and interfering with LDL suppression of cholesterol synthesis in cultured fibroblasts. Increasing the concentration 10-fold did not change the results significantly. Based on these results we have proposed a map of the determinants as they would appear in LDL.
Pulsatile flow in a model carotid bifurcation.
Authors: Ku D N , Giddens D P
Published: June 2011

Pulsatile flow in an in vitro model of the human carotid bifurcation was studied by flow visualization using hydrogen bubble techniques. A glass model was constructed after determining an average geometry from 57 biplanar angiograms of 22 subjects ranging from 34 to 77 years of age. The flow pulse used was a half-sine wave superimposed upon a mean flow. Maximum and minimum values of the instantaneous Reynolds number were 1200 and 400, respectively, based upon conditions in the common carotid model artery; the frequency parameter was 6.0. The division of flow into the internal external branches was 70:30. Visualization by hydrogen bubbles demonstrated significant deviations from steady flow behavior. Flow separated in the carotid sinus over the entire cycle, but the location and extent of separation varied strongly. The direction of flow near the walls of the model changed sharply during the cycle except for the region near the apex of the bifurcation where the orientation of streaklines was more nearly unidirectional at all times. Bubbles entering the separated flow region tended to remain entrapped there for several cycles. Rapid dispersion of bubbles occurred in the internal branch near the end of systole, suggesting the presence of flow disorder. The location of low wall shear stresses, directionally varying stresses, and longer residence times for fluid elements appears to coincide with the localization of early atheromatous plaques in human carotid specimens.
High density lipoprotein apoprotein variability in a biracial population.
Authors: Nestel P , Ringrose H , Taylor R , Zimmet P , Sloman G
Published: June 2011

High density lipoprotein (HDL) cholesterol is a sensitive index for coronary disease in affluent societies. We have measured plasma apoprotein A-I levels (the major HDL protein) in randomly selected groups of urban and rural Fijian Melanesians and Indians. Despite higher prevalence rates of coronary disease and diabetes mellitus in Indians, Indian men and women had significantly higher A-I levels than Melanesian men and women. Multivariate analysis was carried out separately in all men and women of both races and also in younger men and women (less than 45 years old) to determine the predictive values of seven variables that might influence A-I levels. These variables accounted for about 16% of the A-I variation and of this more than one-half was due to ethnic origin. The remainder was largely due to three environmental factors: urbanization, alcohol consumption, and physical activity. Men and women aged 20 to 44 years had significantly higher A-I levels in the town than in villages; alcohol drinkers had significantly higher A-I levels than nondrinkers, and in women physical inactivity resulted in significantly lower A-I levels. Age, smoking cigarettes, and body mass index did not contribute to the differences in A-I levels between the two races, despite less smoking and overweight among Indians. This study of a biracial population, that shares a similar environment but differs in cultural habits, has demonstrated the operation of genetic and environmental factors that explain a minor proportion of apoprotein A-I variability.
Influence of weight reduction on plasma lipoproteins in obese patients.
Authors: Wolf R N , Grundy S M
Published: June 2011

To determine the influence of weight reduction on plasma lipoproteins, studies were carried out in 15 nondiabetic patients of varying degrees of obesity and four obese insulin-dependent diabetics. All studies were carried out on a metabolic ward and patients underwent three dietary periods: Period I, 4 to 5 weeks of weight maintenance in the obese state; Period II, caloric restriction to 1000 kcal/day to a weight loss of within 10% of ideal body weight; and Period III, again weight maintenance for 4 to 5 weeks near ideal body weight. Similar results were obtained for both nondiabetics and diabetics. Many patients had mildly elevated plasma triglycerides in Period I; they fell to the normal range in Period II and remained low in Period III. Total cholesterol levels decreased early in Period II, but levels began to rise near the end of caloric restriction, and in Period III, they were similar to Period I. Low density lipoprotein cholesterol levels followed a pattern similar to that of total cholesterol. High density lipoprotein cholesterol was relatively low in Period I (38 +/- 2 mg/dl +/- SEM); throughout weight loss, levels tended to rise, and in Period III, the average high density lipoprotein cholesterol was significantly higher (46 +/- 2 mg/dl).
Neutral triglyceride lipase in macrophages.
Authors: Khoo J C , Vance J E , Mahoney E M , Jensen D , Wancewicz E , Steinberg D
Published: June 2011

High levels of neutral triglyceride lipase activity have been demonstrated in several types of macrophages (J774 cells, human monocyte/macrophages, rabbit alveolar macrophages, and resident mouse peritoneal macrophages). The pH optima ranged from 6.5 to 7.4 depending upon the buffer and the conditions of incubation. The addition of bovine serum albumin stimulated activity at low concentrations, as expected for a fatty acid-releasing reaction, but strongly inhibited at higher concentrations; maximal activity was observed in the presence of 0.625 mg/ml of bovine serum albumin. The enzyme was remarkably thermostable, showing no apparent loss of activity at 50 degrees C for as long as 6 hours. The lipase was inhibited 80% by 0.1 M NaCl. Assayed under optimal conditions, the specific activity of the neutral triglyceride lipase from J774 cells was more than 100-fold greater than the activity of lipoprotein lipase or neutral cholesterol esterase from those cells; this activity was 10-fold greater than the levels of hormone-sensitive lipase from 3T3-L1 adipocytes. This neutral triglyceride lipase may play an important role in the degradation and mobilization of cytosolic triglyceride in macrophage-derived foam cells.
Homozygous familial hypercholesterolemia occurring with apoprotein E3 deficiency. Report of two cases.
Authors: Nestel P J , Reardon M F , Fidge N H
Published: June 2011

This is the first report of homozygous familial hypercholesterolemia (FH) occurring together with dysbetalipoproteinemia. The former was demonstrated by deficiency of specific receptors for apoprotein B of low density lipoproteins and the latter by isoelectric focusing of the E isoapoproteins and the presence of a broad-beta band on electrophoresis. Two young boys of Lebanese extraction had extensive tuberous and tendinous xanthomata, serum cholesterol concentrations of 29.9 and 28.4 mmol/liter, respectively, and mildly raised serum triglycerides due to an accumulation of lipoprotein remnant particles. Homozygosity for FH was demonstrated in both boys by the deficiency of specific binding of low density lipoprotein to cultured skin fibroblasts (less than 15% and less than 10% of normal, respectively). The E apoprotein phenotypes showed E3/E2 in one boy and E2/E2 in the other. The treatment of both boys with cholestyramine and probucol reduced the serum cholesterol concentration to between 15 and 18 mmol/liter and dramatically lessened the severity of xanthomatosis.
Cholesterol esterification in macrophages. Stimulation by lipoproteins containing apo B isolated from human aortas.
Authors: Clevidence B A , Morton R E , West G , Dusek D M , Hoff H F
Published: June 2011

A lipoprotein fraction possessing many of the characteristics of plasma low density lipoproteins (P-LDL) was isolated from homogenates of lesioned human aortas by affinity chromatography. In contrast to P-LDL, this fraction, termed A-LP, was found to be more electronegative than P-LDL and to stimulate cholesterol esterification in mouse peritoneal macrophages (MPM). This stimulation tended toward saturation at approximately 100 micrograms/ml lipoprotein cholesterol. Cholesterol esterification was partially inhibited by fucoidin, a competitive inhibitor of the scavenger receptor on MPM. These results suggest that A-LP is recognized by a high affinity binding site on MPM. Stimulation of cholesterol esterification in MPM by A-lP was inhibited by the lysosomotropic agent, chloroquine, indicating that degradation in lysosomes was a prerequisite for cholesterol esterification. Substantial degradation of apo B within the intact A-LP was demonstrated by SDS-PAGE and immunoblotting. This degradation could be responsible for the increased negative charge on A-LP, and the enhanced recognition of A-LP by a receptor on MPM. Stimulation of cholesterol esterification increased linearly over a 48-hour time period, suggesting that the receptor on MPM recognizing A-LP was not down-regulated. This unabated increase in cholesterol esterification resulted in massive accumulation of intracellular cholesteryl esters and a gradual increase in oil red O-positive droplets, giving the MPM the characteristic morphology of foam cells. If these mechanisms demonstrated in vitro also occur in the intact artery, they could explain how foam cells are formed within the fatty streak lesion.
Uptake of apolipoprotein E-containing high density lipoproteins by hepatic parenchymal cells.
Authors: Funke H , Boyles J , Weisgraber K H , Ludwig E H , Hui D Y , Mahley R W
Published: June 2011

Cholesterol-enriched, apolipoprotein E-containing high density lipoproteins (apo E HDLc), which were isolated from the plasma of cholesterol-fed dogs by using agarose column chromatography or ultracentrifugation, possessed essentially identical biochemical and metabolic characteristics. Radioiodinated (125I) apo E HDLc isolated by either method gave identical rates of clearance from the plasma, i.e., greater than 50% of the injected dose was cleared from the plasma within 5 to 10 minutes, principally by the liver. Detailed studies localizing apo E HDLc uptake to specific cell types within the liver were performed in both normal and cholesterol-fed rats. The validity of using the canine apo E HDLc in the rat was supported by observations of marked similarities in plasma clearance, i.e., a rapid acute phase of disappearance, and a near-quantitative hepatic uptake of lipoproteins in both species. Canine apo E HDLc (fluorescently labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine), which were injected into normal rats, appeared to be taken up primarily by parenchymal cells, as determined by fluorescence microscopy. Light microscopic autoradiography also revealed that the uptake of 125I apo E HDLc was principally carried out by parenchymal cells in rat liver. Likewise, the uptake of apo E HDLc by the liver of cholesterol-fed rats was extensively localized to parenchymal cells. An in situ, single-pass perfusion of a lobule of the liver of a normal dog with iodinated and fluorescently labeled apo E HDLc confirmed that the uptake of the lipoproteins was principally carried out by parenchymal cells. The plasma clearance of apo E HDLc by hepatic parenchymal cells, even in cholesterol-fed animals in which the apo B,E (LDL) receptors were markedly down-regulated (undetectable), suggests that the apo E receptor, presumably the remnant receptor, is localized in the parenchymal cells.
Abnormalities of high density lipoproteins in homozygous familial hypercholesterolemia.
Authors: Goldberg R B , Fless G M , Baker S G , Joffe B I , Getz G S , Scanu A M , Seftel H C
Published: June 2011

The possibility that low high density lipoprotein (HDL) levels may add to the risk of occlusive atherosclerosis in familial hypercholesterolemia (FH) is supported by the frequency and severity of this finding in these patients, particularly homozygotes. To investigate this abnormality in greater detail, we measured HDL lipid and apoprotein values in nine homozygotes with FH. Compared to their unaffected relatives, they had markedly reduced HDL cholesterol and apo A-I and A-II levels. The values found in heterozygote relatives were between those of homozygotes and those of controls. Density gradient ultracentrifugation of serum or isolated HDL from homozygotes demonstrated little or no HDL2; there was also a shift of homozygotes' HDL to an above normal peak density (d = 1.15 g/ml). Heterozygotes had milder abnormalities. The reduced HDL in FH seems to be related to elevated low density lipoprotein levels although the pathophysiology is unknown. These findings add weight to the concept that HDL abnormalities contribute to the relentless course of atherosclerosis in familial hypercholesterolemia.
Spontaneous and diet-induced coronary atherosclerosis in normal swine and swine with von Willebrand disease.
Authors: Fuster V , Lie J T , Badimon L , Rosemark J A , Badimon J J , Bowie E J
Published: June 2011

We have observed that pigs with impaired platelet function in the form of severe von Willebrand's disease (vWd) are resistant to spontaneous and to diet-induced aortic atherosclerosis. However, it has been reported that vWd pigs are susceptible to coronary atherosclerosis produced by balloon-induced injury of coronary arteries combined with an atherogenic diet. We have evaluated the development of coronary atherosclerosis in normal control (NC) and homozygous vWd pigs in two prospective studies: 1) as a spontaneous process in five NC and vWd pigs receiving a regular diet from the age of 3 months to 4 years; and 2) in nine NC and five vWd receiving a high-fat and high-cholesterol (2%) diet from the age of 3 to 9 months. All of the coronary arteries were analyzed postmortem in 5-mm sections. None of the NC nor the vWd pigs in the spontaneous study showed coronary atherosclerosis or myocardial lesions. In the study of diet-induced atherosclerosis, only one NC and one vWd pig had discrete stenoses; the stenoses affected the three coronary arteries and were significant (50% to 80%) in the NC and mild (greater than 25%) in the vWd pigs; no pigs showed myocardial lesions. Pigs with vWd are resistant to atherosclerosis of the aorta. To assess the resistance or susceptibility to coronary disease in these pigs, a longer follow-up study would be necessary.
Apoprotein B-48 is a constant finding in very low density lipoproteins of humans.
Authors: Cazzolato G , Bittolo Bon G , Avogaro P
Published: June 2011

The results of this study indicate that very low density lipoprotein (VLDL) from the plasma of fasting normolipidemic or slightly hypertriglyceridemic subjects contains two apo B species. In SDS gel electrophoresis, the VLDL shows the presence of a major band corresponding to low density lipoprotein (LDL) apo B (apo B-100) and a minor band with the appropriate mobility of the lymph chylomicron apo B (apo B-48). The reactivity of monoclonal antibodies directed against opportunely selected human apo B suggests that the protein with the lower molecular weight corresponds to apo B-48. This finding was confirmed by using immunoadsorbants and affinity chromatography with monoclonal antibodies that react only with apo B-100. Through this method, VLDL were separated into two fractions: one that had only apo B-100 and one with both apo B-100 and apo B-48. Hepatic and intestinal VLDL may constitute different particles. The ratio of apo B-100 to apo B-48 in VLDL decreased as the mass of fasting plasma VLDL increased. This may improve our understanding of the metabolism of triglyceride-rich lipoproteins. The investigation of the new subspecies of apo B may be relevant in understanding the atherogenetic process and better defining the hyperlipidemic states.
Metabolism of atherogenic lipoproteins by smooth muscle cells of different phenotype in culture.
Authors: Campbell J H , Reardon M F , Campbell G R , Nestel P J
Published: June 2011

Smooth muscle cells of the rabbit aorta, when grown in vitro, express three distinguishable forms of phenotype (contractile, reversible synthetic, and irreversible synthetic). We compared the interactions of these three smooth muscle phenotypes with rabbit very low density lipoprotein (VLDL), low density lipoprotein (LDL), and very low density lipoprotein from cholesterol-fed rabbits (beta-VLDL). beta-VLDL showed saturable. high-affinity binding characteristics with each phenotype predominantly through the B/E receptor. The irreversible synthetic cells displayed the greatest binding capacity and the contractile cells, the least. Binding and degradation of normal VLDL was less than that of beta-VLDL and higher than that of LDL. Only the irreversible synthetic cells showed substantial (about threefold) cholesteryl ester formation and cholesterol accumulation, and then only when incubated with beta-VLDL. Substantial stainable lipid, shown chemically to include triglyceride, cholesterol and cholesteryl ester, was also observed only when irreversible synthetic cells were exposed to beta-VLDL. The high capacity of irreversible synthetic-state, smooth muscle cells to bind and accumulate beta-VLDL in contrast to the relative immunity of contractile cells may be relevant to the genesis of atherosclerosis in the rabbit and possibly also in humans.
Triglyceride-lowering effect of marine polyunsaturates in patients with hypertriglyceridemia.
Authors: Sanders T A , Sullivan D R , Reeve J , Thompson G R
Published: June 2011

Twenty male patients with primary hypertriglyceridemia were treated for 4 weeks with daily supplements (15 g) of oil, which provided approximately 6 g of polyunsaturated fatty acid (PUFA) either of fish or of vegetable origin. Total plasma cholesterol concentrations were unaffected, but both types of supplement increased high density lipoprotein-3 (HDL3) cholesterol concentrations. The fish, but not the vegetable, oil supplement led to a decrease in plasma triglyceride concentrations. Very low density lipoprotein (VLDL), fatty acid composition, and VLDL triglyceride kinetics were subsequently studied in five patients (four male, one female) before and after 4 weeks of therapy with 15 g of the same fish oil. The fish oil led to increases in the proportion of eicosapentaenoic acid in both the VLDL triglyceride and phospholipid fractions, but the increase was greater in the latter. In contrast, the proportion of docosahexanoic acid was increased only in the VLDL triglycerides. The decrease in plasma triglyceride concentrations that occurred with fish-oil therapy was accompanied by a reduction in the absolute catabolic rate of VLDL triglyceride, implying a concomitant change in synthetic rate; the fractional catabolic rate of VLDL triglyceride was unaltered. It is suggested that polyunsaturated fatty acids of marine origin may be therapeutically useful for hypertriglyceridemia.
Demographic, behavioral, biochemical, and dietary correlates of plasma triglycerides. Lipid Research Clinics Program Prevalence Study.
Authors: Cowan L D , Wilcosky T , Criqui M H , Barrett-Connor E , Suchindran C M , Wallace R , Laskarzewski P , Walden C
Published: June 2011

Few studies have simultaneously examined the relationship of triglyceride levels with a wide variety of potential covariates. Thus, the present study was designed to assess in a large, free-living population the association of fasting plasma triglyceride values with selected demographic, behavioral, biochemical, and dietary measures. These analyses were done using data obtained from 5189 white men and women aged 20 to 69 years who participated in the Lipid Research Clinics Program Prevalence Study. Of the eight nondietary factors examined, age, Quetelet Index, fasting plasma glucose, and cigarette smoking were strongly, positively associated (p less than 0.0001) with triglycerides in men and in women not using gonadal hormones. Among women using oral contraceptives or estrogens, only Quetelet Index (p less than 0.01) and cigarette smoking (p = 0.01) were significantly related to triglyceride values. Physical activity was inversely associated (p less than 0.0001) and use of diuretic medications was positively related (p less than 0.01) to triglycerides only in men. Results of analyses of triglycerides and six selected dietary measures varied by age, sex, and hormone-use subgroups. Although none of the dietary variables showed consistent associations with triglycerides across all of the subgroups, triglycerides tended to be inversely associated with total calories per kilogram of body weight and the percentage of calories as dietary fat.
Effects of two forms of hypertension on atherosclerosis in the hyperlipidemic baboon.
Authors: McGill H C , Carey K D , McMahan C A , Marinez Y N , Cooper T E , Mott G E , Schwartz C J
Published: June 2011

We examined the relationship of hypertension and plasma renin activity to atherogenesis in 48 moderately hyperlipidemic (total serum cholesterol was about 200 mg/dl) baboons (Papio sp.). We used renal artery stenosis (two-kidney, one clip model) to produce hypertension associated with elevated plasma renin activity, and used cellophane wrapping of both kidneys (bilateral perinephritis model) to produce hypertension with normal renin activity. Renal artery stenosis and bilateral perinephritis increased both systolic and diastolic blood pressure by about 30 mm Hg. Renal artery stenosis approximately doubled, but bilateral perinephritis did not change plasma renin activity. Both hypertensive groups, to about the same degree, had significantly more extensive atherosclerosis than the control group in the abdominal aorta and brachial, iliac-femoral, and carotid arteries. The effect of hypertension was greatest in the carotid arteries where the extent of atherosclerosis was nearly tripled. Hypertension did not influence lesions in the thoracic aorta. By multiple regression analysis, very low plus low density lipoprotein cholesterol, high density lipoprotein cholesterol, and systolic blood pressure were consistently strong predictive variables for the extent of atherosclerotic lesions. Most of the effects of renal hypertension on atherosclerotic lesions appeared to be accounted for by the increase in blood pressure. In the carotid arteries, however, there was a suggestion of an effect above that due to increased blood pressure. Additional analyses indicated that these treatment effects were associated with serum potassium concentration, plasma renin activity, or other closely related variables.
Regional accumulations of T cells, macrophages, and smooth muscle cells in the human atherosclerotic plaque.
Authors: Jonasson L , Holm J , Skalli O , Bondjers G , Hansson G K
Published: June 2011

The cellular composition of human atherosclerotic plaques was analyzed by immunologic techniques. Plaques were removed from the internal carotid artery during surgery, and a panel of monoclonal antibodies was used to identify cell types. Macrophages stained by Anti-Leu-M3 were found throughout the plaque, particularly in the lipid core region, where 60% of the cells reacted with this antibody. T cells expressing the T3 antigen were most abundant in the fibrous cap, where they constituted 20% of the cell population. T cells were also isolated from the plaque and detected by a rosetting test; many of these T cells were activated, as indicated by the expression of HLA-DR. Other types of leukocytes were uncommon in the plaque. An antibody to the intermediate filament protein, desmin, was used as a marker for smooth muscle cells since some, but not all, vascular smooth muscle cells contain this protein. The desmin-positive cells were uncommon in the nonatherosclerotic intima but were more numerous in the plaque. In conclusion, atherosclerotic plaques are heterogeneous with respect to cellular composition. The smooth muscle cell dominates in the fibrous cap, which also contains many T cells; the lipid core is dominated by macrophages. We suggest that interactions between smooth muscle cells and blood-borne cells are important in the pathogenesis of atherosclerosis.
Development of nonthrombogenicity of injured rabbit aortas despite inhibition of platelet adherence.
Authors: Groves H M , Kinlough-Rathbone R L , Mustard J F
Published: June 2011

After removal of the endothelium from normal rabbit aortas or after injury to the neointima, the injured surfaces rapidly become nonreactive to circulating platelets. Experiments were done to determine whether prevention of the initial interaction of platelets with the surfaces would influence the loss of vessel wall reactivity. Inhibition of platelet accumulation on the subendothelium by the infusion of PGI2 (850 ng/kg/min) or the administration of dipyridamole (12.5 mg/kg initially followed by 5 mg/kg/hr) for periods of less than 8 hours inhibited platelet accumulation of platelets on the surfaces when the infusions were stopped. If the animals were treated for 8 hours, platelets did not accumulate on the surface when the drugs were discontinued. Thus, an injured vessel wall can develop a nonthrombogenic surface even when platelet adherence is prevented, although approximately 8 hours are required before the surface loses its ability to interact with platelets.
Increased fibrinogen binding to platelets from patients with familial hypercholesterolemia.
Authors: DiMinno G , Silver M J , Cerbone A M , Rainone A , Postiglione A , Mancini M
Published: June 2011

Familial hypercholesterolemia (FH) is a disease marked by a high incidence of thrombotic episodes and hypersensitivity of the patients' platelets to naturally occurring aggregating agents. Prostaglandin/thromboxane (PG/Tx) formation, adenosine 5'-diphosphate (ADP) secretion, and fibrinogen binding to platelets are all believed to be involved in the mechanisms of platelet aggregation. Therefore, we studied the interrelated roles of these processes in the platelets of nine FH patients and 10 controls. In response to ADP, collagen, or thrombin, FH platelets bound about twice as much 125I-fibrinogen as controls. This ratio did not change after suppression of PG/Tx formation by aspirin. With or without aspirin, FH platelets always aggregated in response to significantly lower concentrations of these agents than did platelets from normal controls. After stimulation with thrombin or collagen, the hyperaggregable platelets from FH patients were shown to bind significantly more fibrinogen than control platelets even when PG/Tx formation was suppressed (aspirin) and secreted ADP was scavenged (apyrase). To determine whether the increased fibrinogen binding observed in FH platelets is due to a qualitative or quantitative abnormality of the platelet receptor, we used a monoclonal antibody (B79.7) that is specific for the receptor. The amount of B79.7 that bound to platelets from control and FH subjects was similar. In addition (as in normal individuals), the antibody inhibited aggregation and fibrinogen binding of FH platelets.
Suppression of atherosclerosis in cholesterol-fed rabbits by diltiazem injection.
Authors: Sugano M , Nakashima Y , Matsushima T , Takahara K , Takasugi M , Kuroiwa A , Koide O
Published: June 2011

The effects of diltiazem, a calcium antagonist, on the development of atherosclerosis were studied in Japanese white rabbits. The rabbits were examined at the end of 10 weeks on the following regimens; a diet of standard pellets and daily intraperitoneal (ip) injections of saline; a diet of pellets containing 1% cholesterol and daily ip injections of saline; or a diet of pellets containing 1% cholesterol and daily ip injections of diltiazem (50 mg). The plasma total and LDL cholesterol levels for the third group were significantly lower than those of the cholesterol diet group. Macroscopically, atheromatous lesions covered 26.7% +/- 6.7% (mean +/- SE) of the intimal surface of the aorta in the second group, and 0.7% +/- 0.3% in the third group (p less than 0.005). The levels of cholesterol, calcium, and uronic acid in the aortic tissue of the second group were significantly higher than those in the third. We concluded that diltiazem administered intraperitoneally suppresses the plasma total and LDL cholesterol elevation induced by the cholesterol diet and inhibits experimentally-induced atherosclerosis.
In vivo flux of plasma cholesterol into human abdominal aorta with advanced atherosclerosis.
Authors: Bremmelgaard A , Stender S , Lorentzen J , Kjeldsen K
Published: June 2011

To measure the flux of free and esterified cholesterol from plasma into abdominal aortic tissue that had severe atherosclerotic lesions, we intravenously injected two autologous plasma samples containing radioactive cholesterol into patients scheduled for reconstructive arterial surgery. After the injections, blood samples were collected for calculation of the exposure of arterial tissue to labeled free and esterified plasma cholesterol. When tissue specimens were removed a few days after the injection, the aortic influx was determined by the simultaneous use of two differently labeled species of cholesterol. The flux of free and esterified cholesterol into 51 tissue specimens from the abdominal aorta of 12 normocholesterolemic patients was 41 +/- 3 and 45 +/- 3 nmol X cm-2 X day-1 (mean +/- SE), respectively, with 7% to 30% hydrolysis and 8% to 24% esterification of the labeled sterols in the atherosclerotic tissue. The influx was up to 100 times greater than the influx into nonatherosclerotic ascending aorta previously measured in other patients. The cholesterol content of the atherosclerotic tissue corresponded to 16 +/- 3 months (mean +/- SE) of continuous cholesteryl ester influx. Unless counteracted by cholesteryl ester efflux from the plaque, this influx provides enough cholesteryl ester from plasma to cause rapid lesion progression.
Immunocytochemical analysis of cellular components in atherosclerotic lesions. Use of monoclonal antibodies with the Watanabe and fat-fed rabbit.
Authors: Tsukada T , Rosenfeld M , Ross R , Gown A M
Published: June 2011

We have performed immunocytochemical investigations into the distribution of smooth muscle cells and macrophages in the atherosclerotic lesions of the Watanabe heritable hyperlipidemic (WHHL) and fat-fed rabbits. We used monoclonal antibodies specific for muscle cells and macrophages, the latter with a new macrophage-specific monoclonal antibody designated RAM11. Scattered macrophages were observed in the subendothelium in areas of grossly normal aorta. Raised lesions were divided into four major groups, based on qualitative aspects of cell localization: fatty streak, composed predominantly of macrophages; intimal thickening, composed predominantly of smooth muscle cells that displayed considerable morphological heterogeneity with an admixture of macrophages; early fibrous plaques, characterized by approximately equal numbers of smooth muscle cells and macrophages; advanced fibrous plaques, composed of a fibrous cap containing flat smooth muscle cells overlying a macrophage-rich zone of atheromatous debris. These studies demonstrate the nature of the lesions in the two rabbit models and the usefulness of monoclonal antibodies in analyzing the cellular composition of atherosclerotic lesions.
Smooth muscle phenotypic expression in human carotid arteries. II. Atherosclerosis-free diffuse intimal thickenings compared with the media.
Authors: Mosse P R , Campbell G R , Campbell J H
Published: June 2011

The volume fraction of synthetic organelles in smooth muscle cells from areas of atherosclerosis-free, diffuse intimal thickenings (DIT) and media of human carotid artery has been determined morphometrically. Tissue was obtained at autopsy from men and women aged 35 to 80 years, at 6 to 12 hours after death. With both sexes, the volume fraction of synthetic organelles in smooth muscle cells from the DIT was not significantly different from the volume fraction of synthetic organelles in cells of the subjacent media (0.25 and 0.21, respectively). This is in marked contrast to our earlier study in which the volume fraction of synthetic organelles in smooth muscle cells of DIT from a similar region of artery, but adjacent to atheromatous plaques, was highly significantly different from cells of the subjacent media (0.48 and 0.23, respectively). Only in regions near atherosclerotic plaques do the majority of smooth muscle cells of DIT express a different phenotype from cells of the media.
Fatty streak expansion and maturation in Watanabe Heritable Hyperlipemic and comparably hypercholesterolemic fat-fed rabbits.
Authors: Rosenfeld M E , Tsukada T , Chait A , Bierman E L , Gown A M , Ross R
Published: June 2011

This study focuses on the expansion and maturation of the fatty streak in the aorta of Watanabe Heritable Hyperlipemic rabbits and comparably hypercholesterolemic fat-fed rabbits between 2 and 6 months duration of hypercholesterolemia. In both groups of animals, the fatty streaks expanded due to: 1) the formation of multiple layers of a mixed population of macrophage-derived foam cells and lipid-containing smooth muscle cells, 2) the hypertrophy of the macrophage-derived foam cells, 3) the continued accumulation of extracellular matrix, 4) the insudation of plasma components. Immunocytochemical studies utilizing macrophage-specific and muscle-actin-specific monoclonal antibodies indicated that the expanding and mature fatty streaks in both the Watanabe and fat-fed rabbits were primarily composed of macrophage-derived foam cells. Hypertrophy of those foam cells situated immediately beneath the endothelium was associated with retraction of the endothelium and exposure of the intimal foam cells to the circulation. Endothelial retraction with exposure of intimal foam cells may facilitate entry of blood cells and lipoproteins into the lesions and formation of mural thrombi on the surfaces of the exposed cells. Biochemical analyses of the cholesterol content of the arteries indicated that both unesterified cholesterol and cholesteryl esters were deposited to a comparable degree in both the Watanabe and fat-fed rabbits. Thus, the absence of the low density lipoprotein receptor in Watanabe rabbits does not appear to directly influence the accumulation of cholesterol in the artery wall.