bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of probucol on plasma clearance and organ uptake of chylomicrons and VLDLs in normal and diabetic rats.
Authors: Mamo J C , Elsegood C L , Umeda Y , Hirano T , Redgrave T G
Published: June 2011

Probucol was given to rats made diabetic by streptozotocin. Compared with diabetic rats not receiving probucol or with nondiabetic rats, probucol lowered the plasma concentrations of triglycerides, phospholipids, cholesterol, and apolipoprotein B. The concentrations of serum chylomicrons and very low density lipoprotein (VLDL) were also reduced. In control and diabetic rats, probucol enhanced the clearance of endogenously radiolabeled VLDL from the plasma. Clearances from the plasma of rat lymph chylomicrons or chylomicron-like lipid emulsions were slow in diabetic rats. Probucol normalized chylomicron clearance in diabetic rats primarily by restoring hepatic uptake of remnants, which was decreased in diabetes. In diabetic rats, uptake of chylomicron remnants was increased in a number of extrahepatic tissues, including the heart and kidney. Probucol significantly decreased uptake in some extrahepatic tissues. Increased plasma clearance of VLDL and chylomicrons was associated with an increase in the apolipoprotein CII/CIII and apolipoprotein E/C ratios. Orally administered probucol was specifically incorporated into lymph chylomicrons, and clearance of probucol from the plasma exactly paralleled the clearance of chylomicron remnants, as traced with radiolabeled cholesteryl esters. Chylomicron-like emulsions incorporating probucol were exclusively cleared from the plasma by the liver in normal rats. We conclude that in streptozotocin diabetic rats, probucol is an effective hypolipidemic agent because it promotes the clearance of the triglyceride-rich lipoproteins.
Plaque changes and arterial enlargement in atherosclerotic monkeys after manipulation of diet and social environment.
Authors: Kaplan J R , Manuck S B , Adams M R , Williams J K , Register T C , Clarkson T B
Published: June 2011

To study the effects of dietary and social manipulations on lesion progression in male monkeys with established atherosclerosis, 83 animals fed a diet containing 1 mg cholesterol per kcal for 14 months were either necropsied (baseline group, n = 21) or assigned to one of three experimental conditions: 1) a diet containing a high amount of fat and cholesterol and a stressful social situation (HiFC-stress, n = 18); 2) a diet lower in fat and cholesterol and a stressful social situation (LoFC-stress, n = 21); or 3) the low-fat, low-cholesterol diet and a nonstressful social situation (LoFC-no stress, n = 23). After 28 months, all animals were necropsied. Coronary atherogenesis was arrested among monkeys in the LoFC-stress and LoFC-no stress conditions compared with that of animals in the baseline condition (plaque areas of 0.35 mm2, 0.30 mm2, and 0.38 mm2, respectively). Lesions in animals fed the LoFC diet (both stress and no-stress groups) were significantly smaller than those in monkeys in the HiFC-stress condition (0.96 mm2). Furthermore, aortic cholesterol content was significantly decreased and luminal areas were relatively larger among monkeys in both LoFC conditions compared with animals in the baseline and HiFC-stress conditions (p < 0.05 for all). The results demonstrate that a low-fat, low-cholesterol diet can halt plaque development, reduce arterial cholesterol content, and permit compensatory arterial enlargement, processes that were unaffected by social stress in this investigation.
Growth hormone treatment of growth hormone-deficient adults results in a marked increase in Lp(a) and HDL cholesterol concentrations.
Authors: Edén S , Wiklund O , Oscarsson J , Rosén T , Bengtsson B A
Published: June 2011

The effects of growth hormone treatment of adults with adult-onset pituitary insufficiency on lipoproteins and apolipoproteins were investigated. Nine patients, one women and eight men (age range, 34-58 years), who had been treated for pituitary tumors were studied. They had complete pituitary insufficiency with a duration of at least 1 year. All patients received replacement therapy with thyroid hormones, glucocorticoids, and gonadal steroids. The study had a double-blind, placebo-controlled, crossover design for active treatment with recombinant human growth hormone (0.25-0.5 units/kg per week s.c. given each evening) for 6 months. Fasting serum levels of cholesterol; triglycerides; high density lipoprotein and low density lipoprotein cholesterol; apolipoproteins A-I, B, and E; and lipoprotein (a) were measured before and after 6 and 26 weeks of treatment. Lipoprotein (a) concentrations increased markedly during treatment and were about twice as high compared with pretreatment levels. Serum cholesterol and low density lipoprotein cholesterol concentrations were decreased after 6 weeks of treatment, but levels had returned to pretreatment levels after 26 weeks. High density lipoprotein cholesterol concentrations increased during treatment and were significantly higher than pretreatment levels after 26 weeks of treatment. Serum triglyceride concentrations did not change significantly, but in two patients with marked hypertriglyceridemia, growth hormone treatment resulted in a marked decrease. Serum concentrations of apolipoproteins A-I, B, and E did not change significantly, but changes in apolipoprotein A-I and B concentrations were in parallel to those observed for high density lipoprotein cholesterol and low density lipoprotein cholesterol, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Lipoprotein profile characterization of the KKA(y) mouse, a rodent model of type II diabetes, before and after treatment with the insulin-sensitizing agent pioglitazone.
Authors: Castle C K , Colca J R , Melchior G W
Published: June 2011

The purpose of this study was to characterize the lipoprotein profile in the KKA(y) mouse, a rodent model of type II diabetes, before and after treatment with the insulin-sensitizing drug pioglitazone. Analysis of the plasma from untreated KKA(y) mice showed that they were severely hyperglycemic, severely hypertriglyceridemic, and moderately hypercholesterolemic. Agarose column chromatographic analysis showed that essentially all of the triglyceride eluted with very low density lipoprotein, and the majority of the cholesterol eluted with high density lipoprotein. Thus, both the very low density lipoprotein and high density lipoprotein levels were markedly elevated in KKA(y) mice. Analysis of the lipoproteins by agarose electrophoresis-immunoblotting showed that apoprotein A-I and apoprotein B had aberrant electrophoretic behavior, typical of apoproteins that have been modified by nonenzymatic glycosylation. Treatment of KKA(y) mice with pioglitazone for 8 days caused a marked reduction in blood glucose and plasma triglyceride concentrations but had no significant effect on plasma cholesterol concentration or distribution. The aberrant electrophoretic behavior of the apoproteins was corrected to normal by drug treatment. These data show that the KKAy mouse has a severe dyslipoproteinemia that is probably secondary to its insulin resistance, but that its lipoprotein profile differs significantly from that of the insulin-resistant human in that the majority of the plasma cholesterol is carried in high density lipoprotein, and those high density lipoprotein levels are very high.
Increased synthesis of plasminogen activator inhibitor-1 by cultured human endothelial cells exposed to native and modified LDLs. An LDL receptor-independent phenomenon.
Authors: Tremoli E , Camera M , Maderna P , Sironi L , Prati L , Colli S , Piovella F , Bernini F , Corsini A , Mussoni L
Published: June 2011

The effects of native and acetylated low density lipoproteins (LDLs and acetyl-LDLs, respectively) on the release of plasminogen activator inhibitor type 1 (PAI-1) by cultured human umbilical vein endothelial cells (ECs) were evaluated. LDL and acetyl-LDL incubated with ECs for 16-18 hours increased the PAI-1 antigen levels in conditioned medium. At a concentration of 100 micrograms/mL, LDL and acetyl-LDL increased PAI-1 by 10.8 and 12.0 ng/mL, respectively (p < 0.05 and p < 0.01 versus control). The increases in PAI-1 antigen levels exerted by the lipoproteins paralleled the changes in PAI-1 activity. The effect of LDL and acetyl-LDL was concentration dependent and specific for PAI-1 because tissue-type plasminogen activator and expression of procoagulant activity were not affected by either lipoprotein. In addition, total protein synthesis evaluated in [35S] methionine-labeled ECs was not affected, and studies with cycloheximide showed that the effect of LDL and acetyl-LDL on PAI-1 release was due to de novo protein synthesis. Experiments using the C7 monoclonal antibody against the LDL receptor and binding-defective LDL indicated that the effect of LDL on the synthesis of PAI-1 was not dependent on the interaction of the LDLs with their specific receptors. Finally, extensive oxidation of LDL prevented and even reversed the effect of LDL on PAI-1 release by ECs. It is concluded that LDL specifically increases the synthesis of PAI-1 by ECs with mechanisms that are not receptor mediated.
Oxidized low density lipoproteins bind to the scavenger receptor expressed by rabbit smooth muscle cells and macrophages.
Authors: Dejager S , Mietus-Synder M , Pitas R E
Published: June 2011

We have previously demonstrated that the acetylated low density lipoprotein (LDL), or scavenger, receptor expressed by rabbit smooth muscle cells (SMCs) is regulated. Phorbol ester treatment of the cells increased the number of scavenger receptors expressed and the metabolism of acetoacetylated (AcAc) LDL. The current studies examined the interaction of oxidized (Ox) LDL with the rabbit scavenger receptor. The internalization and degradation of both Ox-LDL and AcAc-LDL were increased to a similar extent by phorbol ester treatment of the SMCs. In cross-competition experiments, both Ox-LDL and AcAc-LDL competed equally for the degradation of 125I-Ox-LDL, suggesting that there is no independent receptor for Ox-LDL on these cells. In contrast, only AcAc-LDL competed totally for the degradation of 125I-AcAc-LDL. Similar results were obtained in cross-competition experiments with rabbit macrophages. To determine whether these data were consistent with the binding of both ligands to a single receptor, competition studies were conducted in Chinese hamster ovary fibroblasts transfected with the bovine scavenger receptor. After transfection, the metabolism of both AcAc-LDL and Ox-LDL was increased, in agreement with the previous data from other investigators, and cross-competition studies yielded essentially identical results to those obtained in the SMCs and macrophages. Northern blot analysis with an antisense rabbit scavenger receptor probe detected the same mRNA species in total RNA from rabbit macrophages and SMCs and showed that scavenger receptor mRNA increased dramatically after phorbol ester treatment of SMCs. The probe also detected bovine scavenger receptor mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)
Shear-induced platelet aggregation is potentiated by desmopressin and inhibited by ticlopidine.
Authors: Cattaneo M , Lombardi R , Bettega D , Lecchi A , Mannucci P M
Published: June 2011

Shear-induced platelet aggregation is important in physiological hemostasis and in the pathogenesis of arterial thrombosis. It requires extracellular Ca2+, platelet membrane glycoproteins Ib/IX and IIb/IIIa, von Willebrand factor (vWF), and ADP. We studied the effects of desmopressin (DDAVP), which increases plasma vWF levels and shortens the bleeding time, and of ticlopidine, which inhibits platelet responses to ADP, on shear-induced platelet aggregation. Eleven healthy volunteers were given oral ticlopidine (250 mg b.i.d.) for 7 days. The same subjects were infused intravenously with DDAVP (0.3 micrograms/kg body wt) before the first and after the last doses of ticlopidine. The degree of platelet aggregation induced by shear stress at 25, 50, 75, and 100 dyne/cm2 in a cone-and-plate viscometer, plasma vWF levels, and the bleeding time were measured before and after each DDAVP infusion. Plasma vWF levels and the extent of shear-induced platelet aggregation increased after DDAVP and were correlated. Ticlopidine partially inhibited shear-induced platelet aggregation both before and after DDAVP infusion. The bleeding time, prolonged by ticlopidine, was shortened by DDAVP. Potentiation by DDAVP of shear-induced platelet aggregation may be one mechanism by which the drug shortens the prolonged bleeding time. Since shear-induced platelet aggregation can cause thrombotic occlusions in stenotic arterial vessels, our findings may explain the therapeutic efficacy of ticlopidine in arterial thrombosis.
Favorable long-term effect of a low-fat/high-fiber diet on human blood coagulation and fibrinolysis.
Authors: Marckmann P , Sandström B , Jespersen J
Published: June 2011

In an 8-month strictly controlled dietary study of 16 healthy young men, the long-term effect of a low-fat (26% of energy) high-fiber (4.5 g/MJ) diet on cardiovascular risk markers of the hemostatic system was assessed. Fasting blood sampling was performed during a 4-week baseline period and then monthly during the intervention. A matched control group of 16 men on habitual diets was also monitored. Median fibrinolytic activity of tissue-type plasminogen activator (t-PA) in plasma was significantly elevated (twofold to fourfold) by the experimental diet. A significant increase in the systemic fibrinolytic activity of the euglobulin fraction of plasma was also observed. Median plasma factor VII coagulant activity (F VIIc) was depressed by 5-10% during the first 2 months and the last month of the study period. The dietary change did not significantly affect plasma levels of fibrinogen, t-PA antigen, or plasminogen activator inhibitor type I antigen. In conclusion, young men who were switched from a typical Danish diet high in saturated fat to a low-fat/high-fiber diet showed a permanent increase in plasma fibrinolytic activity and a biphasic decrease in F VIIc. The dietary change thus had a favorable effect on cardiovascular risk markers of the hemostatic system.
Binding of 111In-labeled LDL to platelets of normolipemic volunteers and patients with heterozygous familial hypercholesterolemia.
Authors: Virgolini I , Li S , Qiong Y , Koller E , Banyai M , Angelberger P , Sinzinger H
Published: June 2011

Low density lipoproteins (LDLs) were isolated by ultracentrifugation and radiolabeled with 111In. The in vitro binding of these radiolabels onto platelets of normolipemic volunteers (n = 15) and patients (n = 36) with heterozygous familial hypercholesterolemia (FH) was investigated. Binding was saturable and indicated high-affinity binding sites capable of binding 1,757 +/- 289 ng protein of 111In-LDL per 10(9) platelets (dissociation constant [Kd], 6 +/- 3 micrograms protein/mL) in healthy volunteers and significantly (p < 0.001) lower amounts in the FH patients (mean, 633 +/- 341 ng protein/10(9) platelets; Kd, 10 +/- 5 micrograms protein/mL). The capacity of native LDL to displace bound 111In-LDL by half amounted to 10 +/- 4 micrograms protein/mL in volunteers and 22 +/- 8 micrograms protein/mL in FH patients (p < 0.001). Treatment with gemfibrozil alone or in combination with cholestyramine in 10 patients resulted in increased 111In-LDL binding by platelets (470 +/- 307 [mean +/- SD] ng protein/10(9) platelets before therapy, 948 +/- 650 ng protein/10(9) platelets after 2 months of therapy [p < 0.01], and 1,272 +/- 701 ng protein/10(9) platelets after 6 months of therapy [p < 0.01]). Significant correlations between 111In-LDL binding capacity and apolipoprotein B (r = -0.83, p < 0.001) and LDL cholesterol (r = -0.80, p < 0.000) concentrations were found. Patients with clinically manifested atherosclerosis (p < 0.01) and those with diabetes mellitus (p < 0.05) had significantly lower platelet LDL binding sites. The findings demonstrate 111In-lipoprotein-specific binding sites on human platelets.(ABSTRACT TRUNCATED AT 250 WORDS)
Cilostazol, a novel cyclic AMP phosphodiesterase inhibitor, prevents reocclusion after coronary arterial thrombolysis with recombinant tissue-type plasminogen activator.
Authors: Saitoh S , Saito T , Otake A , Owada T , Mitsugi M , Hashimoto H , Maruyama Y
Published: June 2011

Inhibitors of cyclic nucleotide phosphodiesterase hydrolysis of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate are known to inhibit platelet aggregation, which plays an important role in acute reocclusion after thrombolysis in acute myocardial infarction. In the present study of a canine preparation of coronary artery thrombosis superimposed on high-grade stenosis, we tested whether the antithrombotic agent cilostazol, an inhibitor of cAMP phosphodiesterase, could prevent acute reocclusion or sustain coronary blood flow after thrombolysis when used with recombinant tissue-type plasminogen activator (rt-PA) and heparin. Intravenous infusion of rt-PA (0.5 mg/kg body wt for 30 minutes) and heparin (a 150 IU/kg body wt i.v. bolus and then 25 IU/kg body wt per hour i.v.) was combined with cilostazol (0.6 or 1.8 mg/kg body wt for 60 minutes). Without cilostazol, reperfusion was observed in seven of eight dogs, but reocclusion occurred in six of these seven dogs after 9 +/- 2 minutes. After administration of 1.8 mg/kg body wt cilostazol (group B-2; a 120-minute observation after the start of rt-PA infusion), reperfusion occurred in all seven dogs (p < 0.05 versus control group), and brief cyclic reocclusion was observed in only one dog 63 minutes after reperfusion. At the same dose of cilostazol (group B-2L; a 240-minute observation after the start of rt-PA infusion), reperfusion occurred in all five dogs (p < 0.05 versus control group), and coronary blood flow was well maintained except for one short reocclusion in one dog. Cilostazol inhibited cyclic flow reduction in a dose-dependent fashion.(ABSTRACT TRUNCATED AT 250 WORDS)
Antiplatelet properties of protein S-nitrosothiols derived from nitric oxide and endothelium-derived relaxing factor.
Authors: Simon D I , Stamler J S , Jaraki O , Keaney J F , Osborne J A , Francis S A , Singel D J , Loscalzo J
Published: June 2011

S-nitrosothiols may serve as carriers in the mechanism of action of endothelium-derived relaxing factor (EDRF) by stabilizing the labile nitric oxide (NO) radical from inactivation by reactive species in the physiological milieu and by delivering NO to the heme activator site of guanylyl cyclase. Low-molecular-weight thiols, such as cysteine and glutathione, form S-nitrosothiol adducts with vasodilatory and antiplatelet properties, and protein thiols can interact in the presence of NO and/or EDRF to form uniquely stable S-nitroso-proteins. We now show that the S-nitroso-proteins, S-nitroso-albumin, S-nitroso-tissue type plasminogen activator, and S-nitroso-cathepsin B, have potent antiplatelet effects with an IC50 of approximately 1.5 microM. In the dog, S-nitroso-albumin inhibits ex vivo platelet aggregation and significantly prolongs the template bleeding time from 2.15 +/- 0.13 (mean +/- SEM) to 9.70 +/- 1.24 minutes. The antiplatelet action of S-nitroso-proteins is associated with the stimulation of guanylyl cyclase and a significant decrease in fibrinogen binding to platelets. S-Nitroso-proteins undergo thiol-nitrosothiol exchange with low-molecular-weight thiols to form low-molecular-weight S-nitroso-thiols, and they also interact directly with the platelet surface, both of which processes facilitate generation of NO. These data suggest that S-nitroso-proteins are potent antiplatelet agents and may be intermediates in the antiplatelet mechanism of EDRF action.
Influence of plasma cholesteryl ester transfer activity on the LDL and HDL distribution profiles in normolipidemic subjects.
Authors: Lagrost L , Gandjini H , Athias A , Guyard-Dangremont V , Lallemant C , Gambert P
Published: June 2011

The relations of cholesteryl ester transfer protein (CETP) activity to the distribution of low density lipoproteins (LDLs) and high density lipoproteins (HDLs) were investigated in fasting plasma samples from 27 normolipidemic subjects. LDL and HDL subfractions were separated by electrophoresis on 20-160 g/L and 40-300 g/L polyacrylamide gradient gels, respectively. Subjects were subdivided into two groups according to their LDL pattern. Monodisperse patterns were characterized by the presence of a single LDL band, whereas polydisperse patterns were characterized by the presence of several LDL bands of different sizes. To investigate the influence of lipid transfers on LDL patterns, total plasma was incubated at 37 degrees C in the absence of lecithin:cholesterol acyltransferase (LCAT) activity. The incubation induced a progressive transformation of polydisperse patterns into monodisperse patterns. Under the same conditions, initially monodisperse patterns remained unchanged. Measurements of the rate of radiolabeled cholesteryl esters transferred from HDL3s to very low density lipoproteins (VLDLs) and LDLs revealed that subjects with a monodisperse LDL pattern presented a significantly higher plasma CETP activity than subjects with a polydisperse LDL pattern (301 +/- 85%/hr per milliliter versus 216 +/- 47%/hr per milliliter, respectively; p < 0.02). In addition, when total plasma was incubated for 24 hours at 37 degrees C in the absence of LCAT activity, the relative mass of cholesteryl esters transferred from HDLs to apolipoprotein B-containing lipoproteins was greater in plasma with monodisperse LDL than in plasma with polydisperse LDL (0.23 +/- 0.06 versus 0.17 +/- 0.06, respectively; p < 0.02). These results indicated that in normolipidemic plasma, CETP could play an important role in determining the size distribution of LDL particles. The analysis of lipoprotein cholesterol distribution in the two groups of subjects sustained this hypothesis. Indeed, HDL cholesterol levels, the HDL:VLDL+LDL cholesterol ratio, and the esterified cholesterol:triglyceride ratio in HDL were significantly lower in plasma with the monodisperse LDL pattern than in plasma with the polydisperse LDL pattern (p < 0.01, p < 0.01, and p < 0.02, respectively). Plasma LCAT activity did not differ in the two groups. Plasma CETP activity correlated positively with the level of HDL3b (r = 0.542, p < 0.01) in the entire study population. Whereas plasma LCAT activity correlated negatively with the level of HDL2b (r = -0.455, p < 0.05) and positively with the levels of HDL2a (r = 0.475, p < 0.05) and HDL3a (r = 0.485, p < 0.05), no significant relation was observed with the level of HDL3b.(ABSTRACT TRUNCATED AT 400 WORDS)
Lipid transfer protein-mediated distribution of HDL-derived cholesteryl esters among plasma apo B-containing lipoprotein subpopulations.
Authors: Marzetta C A , Meyers T J , Albers J J
Published: June 2011

The substrate specificity of lipid transfer protein has been examined in whole plasma in vitro by following the redistribution of high density lipoprotein (HDL)-derived [3H]cholesteryl ester (CE) into apolipoprotein (apo) B-containing lipoproteins using density gradient ultracentrifugation. HDL-derived [3H]CEs were incubated with plasma or isolated lipoprotein classes (very low density lipoprotein, intermediate density lipoprotein, and low density lipoprotein [LDL] subpopulations from the HDL donor) with and without lipoprotein lipase for 0.5-6 hours at 37 degrees C. After incubation, lipoproteins were separated into 38 fractions after density gradient ultracentrifugation, and radioactivity, protein, and cholesterol were monitored across the profiles. These studies indicate that 1) lipid transfer protein activity varied among the individuals as well as within an individual; 2) the majority of the [3H]CE was associated with LDL; 3) in most individuals (71%), more HDL-derived [3H]CE distributed within the buoyant LDL density region; and 4) the distribution of HDL-derived [3H]CE was similar to the distribution of lipoprotein lipase-derived "remnant" particles within buoyant LDL. These in vitro studies support the hypothesis that HDL-derived [3H]CEs vary in their distribution among apo B-containing particles and that more HDL-derived [3H]CEs are transferred to lipoproteins within the buoyant LDL density range. Additional studies suggest that lipoprotein heterogeneity within this density range, such as the presence of remnant-like lipoproteins, may contribute to the selective distribution of HDL-derived [3H]CE into buoyant LDL.
Childhood consumption of dietary polyunsaturated fat lowers risk for coronary artery atherosclerosis in African green monkeys.
Authors: Wolfe M S , Parks J S , Morgan T M , Rudel L L
Published: June 2011

This study was designed to test the hypothesis that consumption of diets enriched in polyunsaturated fatty acids beginning at birth and continuing into young adulthood would lower the risk for atherosclerotic coronary heart disease early in life through their effects on plasma lipid and apolipoprotein concentrations while supporting good health and normal development. Accordingly, African green monkeys (n = 140) were raised on atherogenic diets (0.8 mg cholesterol per kcal) enriched with either saturated or n-6 polyunsaturated fatty acids. Breast milk from mothers fed the polyunsaturated fat diet became enriched in polyunsaturated fatty acids relative to the saturated group; thus, the period of nursing also reflected the dietary fatty acid shift. Age, gender, and dietary fat type independently affected plasma lipid and apolipoprotein concentrations. Age effects were similar for all lipid and lipoprotein variables; the concentrations were low immediately after birth, increased dramatically during the first 4-6 months of life, and then attained levels similar to those of adult animals by 2 years of age. Significant differences by gender were found such that females maintained lower total plasma cholesterol concentrations and higher high density lipoprotein (HDL) cholesterol and apolipoprotein (apo) A-I concentrations. Dietary fat effects were age dependent. Before weaning at 5 months of age, total plasma cholesterol and apoB concentrations were lower in animals consuming polyunsaturated fat, and this pattern was maintained into young adulthood. Lower concentrations of plasma triglycerides, HDL cholesterol, and apoA-I for polyunsaturated fat-fed animals were found only in the postweaning period (6-60 months of age). Since this pattern of response to dietary polyunsaturated fat in the juvenile animals was similar to that for adult animals fed these same diets in which there was less atherosclerosis and because subsequent studies have documented less coronary artery atherosclerosis in the polyunsaturated fat-fed juveniles, we conclude that early dietary intervention was beneficial in this group for lowering the risk of coronary artery atherosclerosis. The results in this primate model support the concept that intervention to modify coronary heart disease risk that is initiated early in childhood will have beneficial effects.
Localization and production of plasminogen activator inhibitor-1 in human healthy and atherosclerotic arteries.
Authors: Lupu F , Bergonzelli G E , Heim D A , Cousin E , Genton C Y , Bachmann F , Kruithof E K
Published: June 2011

High plasma levels of plasminogen activator inhibitor type-1 (PAI-1), the principal inhibitor of the fibrinolytic system, have been associated with thrombotic and arterial disease. To study PAI-1 expression in healthy and atherosclerotic human arteries, a detailed analysis was made by light and electron microscopy immunocytochemistry and by in situ hybridization. In healthy arteries PAI-1 was found both at the level of endothelial cells and of smooth muscle cells (SMCs) of the arterial media. In early atherosclerotic lesions PAI-1 was also detected in intimal SMCs and in extracellular areas in association with vitronectin. Immunogold analysis by electron microscopy revealed PAI-1 in vesicular structures in endothelial cells and in SMCs with normal or foam cell characteristics. In advanced atheromatous plaques, PAI-1 mRNA expression in SMCs within the fibrous cap was increased compared with SMCs located in the adjacent media or in normal arterial tissue. PAI-1 mRNA was also detected in macrophages located at the periphery of the necrotic core. The increased synthesis of PAI-1 by cellular components of the atherosclerotic plaque and the extracellular accumulation of PAI-1 may contribute to the thrombotic complications associated with plaque rupture and possibly play a role in the accumulation of extracellular matrix deposits.
Variable expression of the mutation in familial defective apolipoprotein B-100.
Authors: Gallagher J J , Myant N B
Published: June 2011

Although most subjects with familial defective apolipoprotein B-100 (FDB) have raised plasma low-density lipoprotein (LDL) levels, a few have LDL levels within the normal range. We have previously identified two normocholesterolemic FDB heterozygotes in an affected family. Results obtained from a study of this family are compatible with a major genetic contribution to the normocholesterolemia in the two heterozygotes. However, our findings are not compatible with inheritance of a variant normal allele at the apolipoprotein B locus in this family that neutralizes the effect of an FDB allele on the plasma LDL level. Polymorphic variations at the apolipoprotein E and LDL receptor loci did not explain the presence of normal LDL levels in the two heterozygous FDB subjects.
Evidence that turbulence is not the cause of poststenotic dilatation in rabbit carotid arteries.
Authors: Ojha M , Langille B L
Published: June 2011

The purpose of this study was to relate local blood flow conditions to the development of poststenotic dilatation (PSD) in the common carotid arteries of rabbits. We investigated the effects of the geometry of the stenoses on PSD formation to gain insight into the mechanisms of this phenomenon. With short stenoses, the maximum diameter of the PSD after 3 weeks increased from about 25% to 50% above the proximal diameter by increasing the severity of the stenoses from 50% to 60% diameter reduction. By contrast, increasing the length of the constricted region of 60% stenoses did not affect the PSD, and in all cases, the site of maximum dilatation occurred within 3 tube diameters from the stenoses. In vitro studies were conducted with the photochromic tracer technique. The most striking observation was that the transition to turbulence did not occur with a 55% short stenosis. By increasing the severity of this short stenosis to 70%, the transition to very localized turbulence was triggered approximately 6 to 8 tube diameters from the stenosis during the early deceleration phase of the flow cycle. The transition point moved farther downstream by increasing the length of this moderate stenosis. This study demonstrated that PSD can occur under turbulence-free conditions, and even when turbulence was generated, the site of the PSD was remote from that of the localized turbulence zone. The wall shear stress pattern was determined for the long 60% stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)
Dermatan sulfate inhibition of fibrin-rich thrombus formation in nonhuman primates.
Authors: Cadroy Y , Hanson S R , Harker L A
Published: June 2011

Dermatan sulfate (DS), a factor that amplifies plasma heparin cofactor II antithrombin (HCII) activity, has been evaluated in baboons for its relative antithrombotic and antihemostatic effects by use of a model that combines both platelet-rich and fibrin-rich thrombus formation. Thrombus was generated in a two-component thrombogenic device incorporated into exteriorized femoral arteriovenous shunts, in which a proximal segment of collagen-coated tubing induces platelet-rich arterial-type thrombus and distal expanded chambers with disturbed and static flow produce fibrin-rich venous-type thrombus. Thrombus formation was measured as the deposition of autologous 111In-platelets by imaging analysis and by the accumulation of 125I-fibrin. Intravenous infusion of DS at 0.83, 8.3, and 42 mg/kg maintained plasma levels at approximately 7, 70, and 400 micrograms/mL, respectively, throughout the period of study. By enhancing HCII-dependent inactivation of soluble thrombin, DS prolonged the coagulation times, reduced plasma fibrinopeptide A levels, and decreased fibrin-rich thrombus formation in the chamber portion of the device in a dose-dependent manner, ie, the intermediate dose reduced fibrin accumulation by approximately 70% (P < .05). By contrast, neither platelet deposition on collagen nor platelet hemostatic function, assessed with bleeding time determinations, was significantly affected by DS at any dose studied (P > .2 and P > .1, respectively, for the high dose), a finding presumably explained by the resistance of immobilized thrombin to inactivation by DS.
In vitro large-wound re-endothelialization. Inhibition of centrosome redistribution by transient inhibition of transcription after wounding prevents rapid repair.
Authors: Ettenson D S , Gotlieb A I
Published: June 2011

Rapid, efficient re-endothelialization of large wounds is characterized by a specific sequence of cytoskeletal events that occur after wounding. Wounds 1.5 mm wide were created down the middle of confluent porcine aortic endothelial monolayers to study regulation of repair. The wounded cultures were incubated for short periods with cycloheximide or actinomycin D to test the hypothesis that transient inhibition of translation and transcription at the time of wounding disrupts rapid repair by interfering with centrosome redistribution to the front of the cell, an early event associated with cell migration. Although centrosome reorientation did not occur when protein synthesis was inhibited with 20 micrograms/mL cycloheximide for 1 hour before and for up to 4 hours after wounding, reorientation did occur by 2 hours after cycloheximide was washed out. The times taken for the wound to close for cycloheximide-treated and control cells did not differ (60 +/- 1.1 vs 60 +/- 0.8 hours). When transcription was inhibited with 0.25 micrograms/mL actinomycin D for 1 hour before and for 1 hour after wounding, re-endothelialization was dramatically reduced. The time taken for the wound to close was almost five times longer (288 +/- 5.3 hours) than for control cells. The cells moved very slowly, maintaining a flattened, spread-out shape, as opposed to being elongated. The centrosomes did not reorient to the front of the cell throughout the entire period. However, addition of actinomycin D for 2 hours when centrosomes had already moved to the front of the cells (4 hours after wounding) did not reduce subsequent wound repair (60 +/- 1.3 hours). This study supports our hypothesis that centrosome redistribution is essential for efficient wound repair and suggests that redistribution is regulated by transcription of essential gene(s) that is induced immediately after wounding by an unknown short-lived signal. Two possible signals are the loss of cell contact and/or a soluble substance released from the cells at the time of wounding. When the signal is unable to induce transcription, dysfunctional repair occurs by a very slow centrosome-independent process.
Inhibition of thromboxane biosynthesis and platelet function by indobufen in type II diabetes mellitus.
Authors: Davì G , Patrono C , Catalano I , Custro N , Giammarresi C , Ganci A , Cosentino F , Notarbartolo A
Published: June 2011

Indobufen is a reversible inhibitor of platelet prostaglandin G/H-synthase. To verify the dose dependence of the antiplatelet effect of indobufen on ex vivo and in vivo indexes of thromboxane (TX) biosynthesis and TXA2-dependent platelet function, we studied nine patients with non-insulin-dependent diabetes mellitus (NIDDM). This was a randomized, double-blind, crossover study in which each patient was treated with three different daily regimens (50 mg BID, 100 mg BID, and 200 mg BID) of indobufen for 1 week, with a 7-day washout period between treatments. Urinary 11-dehydro-TXB2 excretion averaged 58.2 +/- 21.8 ng/h at baseline. TX metabolite excretion was reduced dose dependently by indobufen: by 67% at 50 mg BID, 72% at 100 mg BID, and 81% at 200 mg BID. Platelet cyclooxygenase activity, ATP release, collagen-induced platelet aggregation, and bleeding time also were modified dose dependently by indobufen. Biochemical demonstration of suppressed platelet TXA2 in vivo was accompanied by evidence of inhibited platelet function as assessed ex vivo. Under pathophysiological conditions, such as NIDDM, which are associated with enhanced TXA2 synthesis, more than 95% suppression of platelet cyclooxygenase activity may be necessary to produce virtually maximal inhibition of platelet TXA2 biosynthesis in vivo.
Fibrinogen and factor VII in the prediction of coronary risk. Results from the PROCAM study in healthy men.
Authors: Heinrich J , Balleisen L , Schulte H , Assmann G , van de Loo J
Published: June 2011

Coronary thrombosis is regarded as the final occlusive event in the progress of coronary heart disease (CHD). Disturbances of the hemostatic system may favor this process and thus may indicate increased risk of myocardial infarction. Coagulation and lipid factors were measured in 2116 healthy male participants of the Prospective Cardiovascular Münster (PROCAM) study. After 6 years of follow-up, 82 coronary events (9 sudden cardiac deaths and 14 fatal and 59 nonfatal myocardial infarctions) were observed. The mean plasma fibrinogen levels of the event and nonevent groups differed by 0.25 g/L (2.88 [SD, 0.68] versus 2.63 [SD, 0.63] g/L, respectively; P = .001). The incidence of coronary events in the upper tertile of the plasma fibrinogen distribution was 2.4-fold higher than in the lower tertile. By multiple logistic function analysis, plasma fibrinogen was found to be an independent risk indicator for CHD (P < .05). Individuals in the high serum low-density lipoprotein (LDL) cholesterol tertile who also showed high plasma fibrinogen concentrations had a 6.1-fold increase in coronary risk. Unexpectedly, individuals with low plasma fibrinogen had a low incidence of coronary events even when serum LDL cholesterol was high. The mean factor VIIc activities in the event and nonevent groups did not differ significantly (112.3% [SD, 19.9] versus 108.4% [SD, 21.6]; P = .09). There was, however, a trend toward higher factor VIIc values when only fatal events were taken into account. Thus, higher levels of plasma fibrinogen markedly increased the predictive power of high serum LDL cholesterol. Low plasma fibrinogen is associated with low coronary risk even when LDL is raised.
Tamoxifen and estrogen lower circulating lipoprotein(a) concentrations in healthy postmenopausal women.
Authors: Shewmon D A , Stock J L , Rosen C J , Heiniluoma K M , Hogue M M , Morrison A , Doyle E M , Ukena T , Weale V , Baker S
Published: June 2011

Data in the literature suggest that circulating levels of lipoprotein(a) [Lp(a)] and insulinlike growth factor I (IGF-I) respond similarly to therapy with growth hormone, estrogen, or tamoxifen. To more clearly document these relations, we designed a randomized, double-blind, placebo-controlled study of the effects of tamoxifen and continuous estrogen on circulating levels of Lp(a), IGF-I, and IGF binding protein 3 (IGFBP-3) in healthy postmenopausal women. Both estrogen and tamoxifen decreased serum levels of IGF-I to 30% below baseline during the 3 months of treatment, while IGFBP-3 levels were unchanged. Plasma Lp(a) levels decreased to 24% below baseline after 1 month of treatment with either estrogen or tamoxifen (P < .05 for estrogen only); after 3 months Lp(a) decreased to 34% below baseline with tamoxifen therapy (P < .05) but returned to only 16% below baseline with estrogen. The correlation between Lp(a) and IGF-I was highly significant (P < .0001). We conclude that (1) tamoxifen lowers plasma Lp(a) levels in healthy postmenopausal women, (2) the suppressive effects of tamoxifen and estrogen on circulating Lp(a) concentration diverge after the first month of therapy, and (3) circulating levels of Lp(a) and IGF-I are strongly correlated with each other, an indication that they may share regulatory influences.
Opposite in vitro and in vivo regulation of hepatic apolipoprotein A-I gene expression by retinoic acid. Absence of effects on apolipoprotein A-II gene expression.
Authors: Berthou L , Staels B , Saldicco I , Berthelot K , Casey J , Fruchart J C , Denèfle P , Branellec D
Published: June 2011

We studied the pharmacological potential of retinoids to modulate apolipoprotein (apo) A-I and apoA-II gene expression and production in vitro in the human cell line HepG2 as well as in primary cultures of adult rat hepatocytes and in vivo in the rat. In HepG2 cells, addition of all-trans retinoic acid (RA) doubled apoA-I mRNA within 24 hours and protein secreted in the culture medium after 48 hours. The induction of apoA-I mRNA by RA was completely blocked by actinomycin D, suggesting that RA acts at the transcriptional level in HepG2 cells. In primary cultures of rat hepatocytes, addition of RA increased apoA-I mRNA in a dose- and time-dependent manner as well as the secretion of apoA-I protein. Similar changes in apoA-I mRNA were observed with 9-cis RA. However, in vivo, hepatic apoA-I mRNA levels decreased after a single administration of RA at 10 mg/kg and remained low after prolonged treatment or at a higher dose, and serum apoA-I concentrations did not change. Furthermore, RA treatment did not substantially affect apoA-II mRNA levels or protein secretion either in vitro or in vivo. As a control, RA receptor-beta mRNA levels increased after RA both in vitro and in vivo. In conclusion, RA treatment selectively induces apoA-I and not apoA-II expression in vitro but not in vivo. These results therefore show additional regulatory effects of RA on apoA-I gene expression in vivo and raise questions about the usefulness of RA in the treatment of atherosclerosis.
Dysbetalipoproteinemia in a kindred with hypobetalipoproteinemia due to mutations in the genes for ApoB (ApoB-70.5) and ApoE (ApoE2).
Authors: Groenewegen W A , Krul E S , Averna M R , Pulai J , Schonfeld G
Published: June 2011

We identified the first insertion mutation that specifies an apolipoprotein (apo)B truncation, apoB-70.5, in a father and son with hypobetalipoproteinemia (total and low-density lipoprotein [LDL] cholesterol < 5th percentile, plasma apoB levels approximately one third of normal). The mutation is due to insertion of an adenine (A) into a 7-A repeat between cDNA position 9754 and 9760 of the apoB gene, resulting in a frame shift of 13 new amino acids and a termination codon at amino acid residue 3197. The DNA mutation cosegregated with the apoB truncation and hypobetalipoproteinemia in the kindred. The two apoB-70.5/apoB-100 heterozygotes also are apoE2 homozygotes by genotyping; beta-very-low-density lipoprotein (VLDL) was present, and VLDL cholesterol/triglyceride ratios were increased (0.29) in the plasmas of both. Density gradient ultracentrifugation and gel filtration chromatography profiles showed increased amounts of particles in the VLDL and intermediate-density lipoprotein density and size ranges and relatively smaller peaks of LDL than in controls. Two populations of LDL were present, ApoB-70.5 was primarily associated with LDL particles of higher density and of smaller size than the LDL particles containing apoB-100. ApoB-48-containing particles were present in the VLDL of fasting plasmas of both subjects, and the postprandial levels of chylomicrons and remnants as measured by the vitamin A fat tolerance test were increased. In conclusion, both subjects heterozygous for apoB-70.5 and homozygous for apoE2 showed the classic characteristics of dysbetalipoproteinemia superimposed onto the hypolipoproteinemia state.
Effect on plasma lipid levels of different classes of mutations in the low-density lipoprotein receptor gene in patients with familial hypercholesterolemia.
Authors: Gudnason V , Day I N , Humphries S E
Published: June 2011

We used the single-strand conformational polymorphism method to screen 311 patients with familial hypercholesterolemia from London lipid clinics and Southampton and South West Hampshire health district for mutations in the 3' part of exon 4 of the low-density lipoprotein (LDL) receptor gene. This part of the gene codes for repeat 5 of the binding domain of the LDL receptor, which is known to be critical for the receptor-mediated removal of both triglyceride-rich lipoprotein remnants and LDL. Six previously described mutations were identified in 29 apparently unrelated individuals (9.3%), with the mutations all lying within a 50-bp fragment of the gene. Three of the mutations are null alleles producing no protein, and the other three lead to production of a defective protein. The effect of the different gene mutations on lipid levels was examined, after the data were combined with information on previously reported mutations in this patient group. Mean LDL cholesterol levels were highest in those individuals with a mutation creating a null allele (9.54 mmol/L) and were similar to levels in those individuals with a mutation affecting repeat 5 that resulted in the production of a defective protein (9.37 mmol/L). In this sample, previously identified patients with a defective protein mutation outside repeat 5 had lower mean levels of LDL cholesterol (7.78 mmol/L), which were similar to levels seen in patients in whom the specific mutation had not been identified (7.31 mmol/L). Overall, these differences were highly statistically significant (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)
Selective inhibition of platelet macroaggregate formation by a recombinant heparin-binding domain of human thrombospondin.
Authors: Legrand C , Morandi V , Mendelovitz S , Shaked H , Hartman J R , Panet A
Published: June 2011

Thrombospondin (TSP) is a platelet alpha-granule adhesive protein that plays a critical role in the stabilization of thrombus by promoting the formation of platelet macroaggregates. We have recently shown that a monoclonal antibody (mAb) to the NH2-terminal heparin-binding domain of TSP, MAII, inhibits platelet aggregation induced by thrombin in a dose-dependent manner. In this study, we have expressed in Escherichia coli two recombinant proteins comprising residues 1 to 174 (TSP18) and 1 to 242 (TSP28) of TSP. After purification, both proteins reacted equally well with mAb MAII, whereas the reactivity of TSP18 for heparin was lower than that of TSP28 or native TSP. At micromolar concentrations, TSP18 and TSP28 inhibited the second wave of platelet aggregation and the concomitant release of [14C]5-hydroxytryptamine induced by ADP in citrated platelet-rich plasma as well as aggregation and secretion induced by a low concentration of thrombin in washed platelet suspensions. The proteins did not inhibit surface expression of endogenous TSP on activated platelets, as measured by the binding of radiolabeled mAb 5G11, indicating that they did not interfere with the primary binding of TSP to the plasma membrane. In contrast, in a solid-phase binding assay, the proteins inhibited in a dose-dependent manner (IC50, 0.1 and 0.06 mumol/L for TSP18 and TSP28, respectively) the binding of radiolabeled TSP to surface-adsorbed fibrinogen. Furthermore, specific and saturable binding of the proteins to immobilized fibrinogen was demonstrated by enzyme-linked immunosorbent assay. The results suggest that interaction between the heparin-binding domain of TSP and membrane-bound fibrinogen may be critical in the platelet aggregation/secretion process.