bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of dietary monounsaturated and polyunsaturated fatty acids on the susceptibility of plasma low density lipoproteins to oxidative modification.
Authors: Bonanome A , Pagnan A , Biffanti S , Opportuno A , Sorgato F , Dorella M , Maiorino M , Ursini F
Published: June 2011

Oxidized low density lipoproteins (LDLs) are thought to play an important role in atherogenesis. Nutritional and biochemical studies suggest that diet can modulate the susceptibility of plasma LDL to undergo oxidative degradation by affecting the concentration of polyunsaturated fatty acids and antioxidants in the lipoprotein particle. In the present study 11 healthy male volunteers underwent two diet phases. In one phase the diet was enriched in oleic acid (mono), while in the other it was high in linoleic acid (poly). Both diets lowered plasma total and LDL cholesterol contents. The sensitivity of plasma LDL to oxidation was estimated by challenging these lipoproteins with 2,2'-azobis(2-amidinopropane)dihydrochloride, a free-radical initiator. Although neither diet affected the antioxidant content of plasma LDL, the resistance to lipid peroxidation, measured after the consumption of antioxidants present in the lipoprotein, was higher during the mono phase. Indeed, the peroxidation rate of plasma LDL was inversely correlated with the oleic acid to linoleic acid ratio in the LDL particle. These results support the thesis that diets rich in monounsaturated fatty acids increase the resistance of plasma LDL to oxidative modification, independent of their content of antioxidants. This effect could lower the atherogenicity of these lipoproteins.
Effect of arterial proteoglycans and glycosaminoglycans on low density lipoprotein oxidation and its uptake by human macrophages and arterial smooth muscle cells.
Authors: Hurt-Camejo E , Camejo G , Rosengren B , López F , Ahlström C , Fager G , Bondjers G
Published: June 2011

The reversible interaction of low density lipoprotein (LDL) with arterial chondroitin sulfate proteoglycans (CSPGs) or glycosaminoglycans (GAGs) selects LDL particles with a high affinity for sulfated GAGs and also induces modifications in apolipoprotein B (apo B) and the lipid organization of the lipoprotein. In the present work we studied the effect that the reversible interaction with sulfated polysaccharides has on the susceptibility of LDL to in vitro oxidation. For this purpose soluble, nonaggregated CSPG- or GAG-treated LDL was subjected to oxidation in the presence of 5 microM CuSO4 for as long as 48 hours. The rate of formation of thiobarbituric acid-reactive substances, the decrease in isoelectric point, the increase in relative electrophoretic mobility of LDL, the higher degradation rate by human macrophages, and the lower degradation rate by human arterial smooth muscle cells showed that LDLs exposed to CSPGs and GAGs were significantly more susceptible to oxidation than native LDL. Results from competition experiments indicate that C6S-treated LDL after 4 hours of oxidation is taken up via the acetylated LDL receptor in human macrophages. Coincubation of lipoproteins with human macrophages or human arterial smooth muscle cells for 24 hours also indicated that C6S-treated LDL was more susceptible to cell-induced modifications than native LDL. The occurrence in vivo of similar processes may contribute to focal retention, increased rate oxidation of LDL in the arterial intima, and foam cell formation during atherogenesis.
High density lipoprotein deficiency syndrome in chickens is not associated with an increased susceptibility to atherosclerosis.
Authors: Poernama F , Subramanian R , Cook M E , Attie A D
Published: June 2011

A spontaneous high density lipoprotein (HDL) deficiency syndrome in chickens associated with a Z-linked (sex-linked) mutation has been reported (F. Poernama et al, J Lipid Res 1990;31:955-963). The mutant, called WHAM (Wisconsin hypo-alpha mutant), has a 70-90% reduction in plasma HDL cholesterol and apolipoprotein A-I (apo A-I) concentrations. In the present study, the effect of the HDL deficiency on diet-induced or spontaneous atherosclerosis was assessed. Control chickens maintained on a high-cholesterol diet for 28 weeks experienced a 2.4-fold rise in the plasma very low density lipoprotein cholesterol concentration, while the same diet induced a 3.7-fold rise in the low density lipoprotein cholesterol concentration in WHAM chickens. The high-cholesterol diet did not elevate the plasma HDL cholesterol or apo A-I concentrations in either group. Both the aortic area of involvement and the width of lesions were quantified by gross and microscopic examination, respectively. Cholesterol feeding produced a significant increase in the area of the aorta with atherosclerotic lesions in both control and mutant chickens. The HDL deficiency in WHAM chickens did not correlate with a higher lesion area or increased lesion thickness. To assess the effect of HDL deficiency on spontaneous atherosclerosis, a separate group of control and WHAM chickens was maintained on a low-fat, cholesterol-free diet for 3 years. At the end of the 3-year period, the area and thickness of the spontaneous aortic lesions in control and WHAM chickens were not significantly different. Spontaneous HDL deficiency in chickens is therefore not associated with increased susceptibility to atherosclerosis.
Comparative copper coil-induced thrombogenicity of the internal mammary, left anterior descending coronary, and popliteal arteries in dogs.
Authors: Rapold H J , Stassen T , Van de Werf F , Collen D
Published: June 2011

The internal mammary artery (IMA) is the graft of choice for coronary artery bypass surgery because of its resistance to atherosclerosis. Studies to elucidate the mechanism of this phenomenon have focused on vasoactive properties of the vessel wall; however, low thrombogenicity might also contribute to the protection of the IMA against atherosclerosis. To test this hypothesis, copper coils 3 mm long were introduced in 14 heparinized dogs into both the IMA and the left anterior descending coronary artery (LAD) (n = 7) or into both the IMA and the popliteal artery (POP) (n = 7). Arterial patency was monitored angiographically at 15-minute intervals for 4 hours. Occlusion occurred in all LADs and POPs and in 10 of the 14 IMAs. Spontaneous reflow after occlusion occurred in all IMAs and was followed by cyclic reocclusion and reflow in two animals. Short periods of reflow followed by reocclusion occurred in two of the seven LADs and three of the seven POPs. The patency status, categorized as persistent occlusion, reflow followed by reocclusion, reflow without reocclusion, or persistent patency, was significantly different between IMA and LAD (p less than 0.02) and between IMA and POP (p less than 0.04) but not between LAD and POP. Patent arteries at the end of the 4-hour period were observed in all of the 14 IMAs versus none of the seven LADs and two of the seven POPs (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Relation between 25-hydroxyvitamin D3, apolipoprotein A-I, and high density lipoprotein cholesterol.
Authors: Auwerx J , Bouillon R , Kesteloot H
Published: June 2011

In a survey of cardiovascular risk factors in 185 men and 173 women of a Belgian population group, an independent and highly significant positive correlation was found between the serum concentrations of 25-hydroxyvitamin D3 and apolipoprotein A-I (p less than 0.001 in both sexes). 25-Hydroxyvitamin D3 also showed a positive correlation with high density lipoprotein cholesterol levels (p less than 0.05 in men and p less than 0.005 in women). This relation was independent of a possible effect of 25-hydroxyvitamin D3 on serum calcium. Taking the biological variation of 25-hydroxyvitamin D3 levels (+/- 2 SD = 25 ng/ml) into account, these findings could explain variations in the levels of apolipoprotein A-I of 15 mg/100 ml and of high density lipoprotein cholesterol of 4 mg/100 ml.
Apolipoprotein B mRNA abundance is decreased by eicosapentaenoic acid in CaCo-2 cells. Effect on the synthesis and secretion of apolipoprotein B.
Authors: Murthy S , Albright E , Mathur S N , Davidson N O , Field F J
Published: June 2011

The regulation of apolipoprotein B (apo B) metabolism by eicosapentaenoic acid was investigated in CaCo-2 cells. Cells cultured on semipermeable membranes that separated an upper from a lower well were incubated for 48 hours with albumin alone or 1 mM eicosapentaenoic acid or oleic acid attached to albumin (4:1, mol/mol). Compared with cells incubated with oleic acid, cells incubated with eicosapentaenoic acid synthesized and secreted less [3H]glycerol-labeled triglycerides. Although both fatty acids increased cellular triglyceride mass compared with control cells, less triglycerides accumulated in cells incubated with the n-3 fatty acid. The secretion of triglyceride and apo B mass by cells incubated with eicosapentaenoic acid was less than that observed by cells incubated with oleate. The amount of apo B mass within cells, however, was not altered by either of the fatty acids and was similar to amounts found in control cells. Apo B mRNA abundance was decreased fourfold in cells exposed for 48 hours to eicosapentaenoic acid. In contrast, in cells incubated with oleic acid, apo B mRNA levels were not significantly altered. Pulse-chase experiments were performed to investigate the regulation of apo B synthesis and degradation by the fatty acids. In cells incubated with eicosapentaenoic acid, the synthesis and basolateral secretion of newly synthesized apo B-100 and apo B-48 were significantly less compared with control cells or cells incubated with oleic acid. In contrast, the synthesis and secretion of newly synthesized apo B in cells exposed to oleic acid were similar to control cells. Rates of apo A-I synthesis were similar in cells incubated with either of the fatty acids. Compared with control cells and cells incubated with eicosapentaenoic acid, the residence time of labeled apo B in cells incubated with oleic acid was prolonged. The percentage of newly synthesized apo B that was degraded was less in cells incubated with oleic acid. In contrast, residence times and the percentages of apo A-I and apo B-48 degraded were similar in control cells and cells incubated with the fatty acids. Thus, in CaCo-2 cells, compared with the effects of oleic acid, eicosapentaenoic acid impairs triglyceride transport in part by inhibiting apo B synthesis and secretion. The inhibition of apo B synthesis by eicosapentaenoic acid may be related to a decrease in gene transcription or a decrease in mRNA stability, as apo B mRNA levels were significantly decreased in cells incubated with this fatty acid.(ABSTRACT TRUNCATED AT 400 WORDS)
Antifibrinolytic activities of alpha-N-acetyl-L-lysine methyl ester, epsilon-aminocaproic acid, and tranexamic acid. Importance of kringle interactions and active site inhibition.
Authors: Anonick P K , Vasudevan J , Gonias S L
Published: June 2011

alpha-N-acetyl-L-lysine methyl ester (NALME) is a lysine analogue that reportedly binds to low-affinity lysine binding sites in plasmin(ogen) and miniplasmin(ogen). In the studies presented here, we show that NALME has antifibrinolytic activity; however, unlike the therapeutic agents epsilon-amino-n-caproic acid (epsilon ACA) and tranexamic acid (TEA), the activity of NALME is based on inhibition of the plasmin active site. NALME (0.1-10 mM) significantly inhibited the amidase activity of plasmin, miniplasmin, and streptokinase-plasmin complex without affecting alpha-thrombin or tissue plasminogen activator. epsilon ACA and TEA (0.1-10 mM) did not affect the amidase activity of plasmin or miniplasmin. A kinetic analysis showed that NALME is a competitive inhibitor of D-Val-L-Lys-p-nitroanilide HCl (S-2251) hydrolysis by plasmin; NALME binding to plasmin completely prevented S-2251 binding. The Kl for the plasmin-NALME interaction was 0.4 mM. epsilon ACA and TEA inhibited fibrin monomer digestion by plasmin and miniplasmin without binding to the active site of either enzyme. This result suggests that epsilon ACA and TEA function as antifibrinolytics by disrupting the noncovalent association of fibrin monomer with a domain common to both plasmin and miniplasmin (probably kringle 5). NALME inhibited fibrin monomer digestion principally by decreasing amidase activity. NALME was the only lysine analogue that prevented fragment X formation; TEA and epsilon ACA primarily inhibited the formation of fragments Y and D. When plasmin was incubated simultaneously with alpha 2-antiplasmin and alpha 2-macroglobulin, epsilon ACA increased the fraction of plasmin reacting with alpha 2-macroglobulin; NALME had no effect on the plasmin distribution.(ABSTRACT TRUNCATED AT 250 WORDS)
In vivo metabolism of apolipoprotein A-I in a patient with homozygous familial hypercholesterolemia.
Authors: Schaefer J R , Rader D J , Ikewaki K , Fairwell T , Zech L A , Kindt M R , Davignon J , Gregg R E , Brewer H B
Published: June 2011

Familial hypercholesterolemia (FH), caused by a defect in the low density lipoprotein (LDL) receptor, results in high plasma concentrations of LDL cholesterol due to both overproduction and delayed catabolism of LDL. FH is also associated with significantly lower levels of plasma high density lipoprotein cholesterol and apolipoprotein (apo) A-I in both heterozygous and homozygous patients. However, the metabolic basis of the hypoalphalipoproteinemia in FH has not been elucidated. We investigated the kinetics of apo A-I in a homozygous FH patient and two normal control subjects by using endogenous labeling with a stable isotopically labeled amino acid. Study subjects were administered a primed constant infusion of 13C6-phenylalanine for 12 hours. Apolipoproteins were isolated from plasma drawn at selected time points and analyzed for their isotopic enrichment by gas chromatography-mass spectrometry. The fractional catabolic rate of apo A-I in the FH subject was found to be substantially increased (0.38 day-1) compared with that of the normal subjects (mean, 0.26 day-1). In addition, the apo A-I production rate was decreased in the FH subject (6.5 mg/kg.day-1) compared with the normal subjects (mean, 11.1 mg/kg.day-1). In conclusion, the low levels of high density lipoprotein cholesterol and apo A-I in this homozygous FH patient are due to the combined metabolic defects of increased apo A-I catabolism and decreased apo A-I production.
Binding of 111In-labeled HDL to platelets from normolipemic volunteers and patients with heterozygous familial hypercholesterolemia.
Authors: Virgolini I , Li S , Yang Q , Banyai M , Koller E , Angelberger P , Sinzinger H
Published: June 2011

High density lipoproteins (HDLs; d = 1.063 - 1.21 g/ml) were isolated by ultracentrifugation and radiolabeled with 111In. The in vitro binding onto platelets from healthy volunteers (n = 15) and patients (n = 36) with heterozygous familial hypercholesterolemia (FH) was investigated. Binding was saturable and indicated high-affinity binding sites, which bound 1,882 +/- 361 ng protein of 111In-HDL/10(9) platelets (dissociation constant [Kd] = 7 +/- 3 micrograms protein/ml) in healthy volunteers and significantly (p less than 0.01) lower amounts in the FH patients (1,012 +/- 439 ng protein of 111In-HDL/10(9) platelets [Kd = 12 +/- 4 micrograms protein/ml]; p less than 0.01). The capacity to displace one half of the bound ligand (IC50) amounted to 14 +/- 3 micrograms protein/ml in healthy volunteers and 22 +/- 9 micrograms protein/ml in FH patients (p less than 0.001). Treatment with lipid-lowering drugs (gemfibrozil, alone or in combination with cholestyramine) in 10 patients resulted in an increased HDL binding capacity: before treatment, 1,280 +/- 883; after 2 months of treatment, 2,052 +/- 873 (p less than 0.05); and after 6 months of treatment, 2,127 +/- 812 ng protein/10(9) platelets (p less than 0.01). There was a significant (p less than 0.001) correlation between 111In-HDL binding data and plasmatic lipid and lipoprotein values. Furthermore, those FH patients with the additional risk factors of smoking (p less than 0.05) and hypertension (p less than 0.01) showed significantly lower 111In-HDL binding onto platelets. The findings indicate specific 111In-HDL binding sites for human platelets, which may be decreased in patients with heterozygous FH. Upregulation of HDL binding sites during lipid-lowering medication therapy supports the hypothesis that high-affinity HDL binding is involved in hyperlipemic disorders and is possibly related to the reactivity of platelets.
Endocytosis of oxidized LDL and reversibility of migration inhibition in macrophage-derived foam cells in vitro. A mechanism for atherosclerosis regression?
Authors: Pataki M , Lusztig G , Robenek H
Published: June 2011

The ability of macrophage-derived foam cells to migrate from atherosclerotic lesions represents one potential mechanism for the regression of atherosclerosis. It is, however, generally recognized that the transformation of macrophages into foam cells results in greatly reduced migrational ability. In the present study, we set out to investigate the factors affecting migratory capability in foam cell-like cells with the use of an in vitro assay. Foam cell-like cells were prepared by incubating macrophages in the presence of oxidized low density lipoprotein (LDL). The transformation to a typical foam cell morphology was demonstrated by Nile red staining (light microscopy), and the mechanisms of binding, uptake, and intracellular processing of oxidized LDL were established by colloidal gold labeling on the ultrastructural level. With the in vitro assay, the migration of these foam cell-like cells was found to be markedly inhibited compared with untreated, control macrophages. However, zymosan-activated mouse serum restored migration in oxidized LDL-treated cells to levels similar to those of control cells. Restoration of migratory capacity was accompanied by alterations in the cytoskeleton system, especially in actin arrangement.
Cholesterol absorption, elimination, and synthesis related to LDL kinetics during varying fat intake in men with different apoprotein E phenotypes.
Authors: Miettinen T A , Gylling H , Vanhanen H , Ollus A
Published: June 2011

Cholesterol absorption, fecal elimination, and synthesis and low density lipoprotein (LDL) metabolism were measured in 29 middle-aged men while on their normal diet and a diet low in fat and cholesterol, and the obtained values were related to apoprotein (apo) E phenotypes. Basal cholesterol absorption efficiency was positively related to production rate (PR) for LDL apo B and negatively to cholesterol synthesis (measured by fecal steroids and dietary cholesterol), which in turn was negatively associated with the LDL level and positively with the fractional removal (FCR) of LDL apo B. The apo E subscript (e.g., E2/2 = 1, E2/3 = 2, etc.) was positively associated with cholesterol absorption and the LDL apo B and cholesterol levels and negatively with cholesterol synthesis and FCR for LDL apo B. Effective bile acid and cholesterol synthesis, fecal elimination of cholesterol, removal of LDL apo B, and low cholesterol absorption characterized men with the epsilon 2 allele. Reduction of dietary fat and cholesterol intakes lowered LDL cholesterol levels and cholesterol absorption but increased cholesterol synthesis proportionally to the apo E subscript; the FCR and PR for LDL apo B were significantly increased and decreased, respectively. The decrease in absorption was related to enhanced removal of LDL apo B and synthesis of cholesterol. During the modified diet, cholesterol metabolism was poorly related to LDL, apo E phenotypes, and LDL apo B kinetics. A positive correlation of cholesterol absorption with dietary fat intake in combined studies suggests that a dietary fat reduction-associated decrease in LDL cholesterol is at least partly caused by reduced cholesterol absorption.(ABSTRACT TRUNCATED AT 250 WORDS)
Fibrinogenolytic and fibrinolytic activity of cell-associated plasmin.
Authors: Humphries J E , Vasudevan J , Gonias S L
Published: June 2011

Binding of plasmin(ogen) to rat C6 glioma cells is saturable and kringle-domain dependent. This interaction was studied as a model of plasmin(ogen) receptor interactions in nucleated mammalian cells. Apparent 125I-plasmin dissociation from C6 cell binding sites was slow; however, the dissociation rate was increased when the solution contained diisopropyl phosphoryl-plasmin (0.3 microM), fibrinogen (0.16 or 0.8 mg/ml), 1.08 mM D-Val-L-Leu-L-Lys-p-nitroanilide-HCl (S-2251), or epsilon-amino-n-caproic acid (EACA, 5.0 mM). EACA promoted the most rapid dissociation of plasmin. C6 cell-associated plasmin and plasmin in solution demonstrated similar amidase activity. Only specifically bound plasmin (75% of total binding) was active against S-2251. Plasmin that was initially bound to C6 cells digested fibrinogen in a time- and plasmin concentration-dependent manner. alpha 2-Antiplasmin (alpha 2AP, 0.1 microM) completely inhibited fibrinogenolysis by plasmin that was initially C6- or human umbilical vein endothelial-cell associated. Since alpha 2AP reacts selectively with plasmin in solution (minimally with plasmin bound to cells), fibrinogen digestion by cell-associated plasmin probably occurred only after the plasmin dissociated into solution. Crosslinked fibrin clots were formed in uniform layers over C6 cells. If the cells were incubated with plasmin before addition of fibrinogen and thrombin, the clots were rapidly lysed. alpha 2AP incompletely inhibited fibrinolysis when added after fibrin polymerization (44% inhibition with 0.1 microM alpha 2AP). Fibrinolysis was completely inhibited when alpha 2AP was added before fibrin polymerization. These studies suggest that plasmin must first dissociate from cellular binding sites to mediate fibrinogenolysis or fibrinolysis.(ABSTRACT TRUNCATED AT 250 WORDS)
Potential of 99mTc-LDLs labeled by two different methods for scintigraphic detection of experimental atherosclerosis in rabbits.
Authors: Atsma D E , Feitsma R I , Camps J , van't Hooft F M , van der Wall E E , Nieuwenhuizen W , Pauwels E K
Published: June 2011

In this study we evaluated two different 99mTc-labeling techniques to produce 99mTc-low density lipoprotein (99mTc-LDL) suitable for the scintigraphic delineation of experimental atherosclerotic lesions. The two methods are 1) a procedure that uses stannous chloride and sodium borohydride (borohydride method) and 2) a procedure that uses sodium dithionite as a reducing agent and that has been successfully applied in previous scintigraphic atherosclerosis detection (dithionite method). 99mTc-LDL produced by either method was injected into New Zealand White rabbits with diet-induced atherosclerotic plaques and in control rabbits. Scintigraphic images were taken 10 minutes (t = 0) and 1, 4, 8, 16, and 24 hours after injection. Clearance of plasma radioactivity was also studied. Stability of the 99mTc-LDL complex in the circulation was examined by size exclusion chromatography of plasma samples. After scintigraphy, the animals were killed, and the biodistribution of radioactivity was determined. The thoracic and abdominal aortas appeared in scintigraphic images to accumulate 99mTc over their entire length with either 99mTc-LDL preparation. The sparse imaging of focal atherosclerosis was found to be due to the fact that the aortas were covered with confluent atherosclerotic lesions. Scintigraphic image analysis showed that 24 hours after injection, the accumulated radioactivity in the abdominal aorta of the atherosclerotic rabbits was 57% and 54%, respectively, of the accumulated radioactivity in the abdominal aorta at t = 0 when the borohydride versus the dithionite method was used. In the control animals this value was 25% for the dithionite method, whereas in the borohydride method the aortas could not be detected in the images at t = 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)
Arterial alterations with aging and high blood pressure. A noninvasive study of carotid and femoral arteries.
Authors: Benetos A , Laurent S , Hoeks A P , Boutouyrie P H , Safar M E
Published: June 2011

Noninvasive in situ evaluations of pulsatile changes of blood pressure and arterial diameter were performed at the sites of the common carotid and femoral arteries in a population of 78 untreated normotensive and hypertensive subjects. Arterial segments were studied by using an original echo-tracking technique for internal diameter and validated applanation tonometry for local pulse pressure measurements. Whereas mean arterial pressure is known to be identical in all parts of the arterial tree, pulse pressure was significantly lower in the carotid (52.7 +/- 2.2 mm Hg) than in the brachial (62.0 +/- 2.0 mm Hg) or femoral (62.5 +/- 2.5 mm Hg) arteries. Despite a higher pulse pressure and diastolic diameter, the femoral artery had a lower pulsatile change in diameter (3.47 +/- 0.18% versus 6.07 +/- 0.28%; p < 0.0001) and distensibility coefficient (9.36 +/- 0.58 versus 21.60 +/- 1.75 x 10(-3) kPa-1) than the carotid artery. Local cross-sectional compliance of the carotid artery was higher than that of the femoral artery (7.42 +/- 0.46 versus 6.20 +/- 0.28 m2.kPa-1.10(-7); p < 0.05). Whereas age was strongly correlated with arterial parameters at the site of the carotid artery (pulse pressure: r = 0.54, p < 0.0001; pulsatile change in arterial diameter: r = -0.62, p < 0.0001; distensibility coefficient: r = -0.70, p < 0.0001), no significant correlation was observed at the femoral artery. Mean blood pressure was the second factor of carotid artery alterations: the higher the mean blood pressure, the lower the distensibility of this artery (r = -0.36, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Biphasic effects of low-molecular-weight and conventional heparins on chylomicron clearance in rats.
Authors: Chevreuil O , Hultin M , Ostergaard P , Olivecrona T
Published: June 2011

Chylomicrons labeled in vivo with [14C]triglycerides and [3H]retinyl esters were injected in rats at a series of times after administration of conventional unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), or saline. In saline controls the clearance of both chylomicron triglycerides and retinyl esters seemed to follow exponential courses, with half-lives of about 5 and 10 minutes, respectively. Five minutes after administration of LMWH or UFH, the triglyceride clearance rates were dramatically increased and were associated with an increased appearance of the radiolabel in circulating free fatty acids (FFAs). The clearance of [3H]retinol radioactivity, ie, chylomicron particles, was also enhanced 5 minutes after heparin injection. From 75% to 90% disappeared from the circulation within the first 5 minutes. Their continued disappearance was much slower, with a slope similar to that of the saline-treated rats. Hence, it was as if a new, rapid exponent had been added to the disappearance curve that accounted for most of the particle clearance. Injection of chylomicrons 1 hour after the heparins resulted in substantially slower clearance compared with saline-treated controls of both triglyceride and retinol radioactivity in rats given a high dose of LMWH or a low dose of either heparin. Appearance of label in plasma FFAs was also decreased, suggesting that impeded lipolysis was responsible, at least in part, for the impeded chylomicron clearance. Four and 24 hours after heparin injection all studied parameters of chylomicron clearance had returned to normal.(ABSTRACT TRUNCATED AT 250 WORDS)
Obese men with type IIB hyperlipidemia are insulin resistant.
Authors: Karhapää P , Voutilainen E , Malkki M , Laakso M
Published: June 2011

By using the euglycemic clamp technique and indirect calorimetry, we determined the degree of insulin resistance in 12 obese (body mass index > 27.0 kg/m2), normotensive patients with type IIB hyperlipidemia (HLIIB) (total cholesterol > or = 6.5 mmol/L and total triglycerides > or = 2.0 mmol/L) and 17 control subjects (total cholesterol < or = 6.1 mmol/L and total triglycerides < 1.8 mmol/L) who were carefully matched for sex, age, and obesity. Fasting plasma insulin was higher in HLIIB patients than in control subjects (18.4 +/- 4.6 versus 8.9 +/- 1.2 mU/L, respectively; P = .010). The rates of whole-body glucose uptake were significantly lower in HLIIB patients than in control subjects during the last hour of the clamp (42.2 +/- 3.9 versus 54.6 +/- 2.8 mumol/kg per minute, respectively; P = .013). Glucose oxidation during the last 30 minutes of the euglycemic clamp was lower in HLIIB patients than in control subjects (14.6 +/- 0.9 versus 19.0 +/- 1.3 mumol/kg per minute, respectively; P = .017). Nonoxidative glucose disposal during the last 30 minutes of the euglycemic clamp was also lower in HLIIB patients than in control subjects, but the difference was not statistically significant (27.6 +/- 3.3 versus 35.8 +/- 2.8 mumol/kg per minute, respectively; P = .069). Lipid oxidation during the clamp was completely suppressed in control subjects (-0.24 +/- 0.44 mumol/kg per minute) but was significantly less suppressed in the HLIIB patients (0.94 +/- 0.29 mumol/kg per minute, P = .024).(ABSTRACT TRUNCATED AT 250 WORDS)
ApoA-IV is secreted on discrete HDL particles by the rat hepatoma cell line McA-RH7777 transfected with ApoA-IV cDNA.
Authors: Yao Z , Lauer S J , Sanan D A , Fazio S
Published: June 2011

In the present study, the synthesis and secretion of transfected apolipoprotein (apo) A-IV was investigated in rat hepatoma McA-RH7777, a cell line that does not express apoA-IV mRNA or protein. An expression plasmid that contained the rat apoA-IV cDNA was transfected into the cells; five stable transformants were selected that harbor different copy numbers of the apoA-IV construct and secrete different amounts of apoA-IV. Gel filtration column chromatography and density gradient ultracentrifugation, combined with gel electrophoresis and electron microscopy techniques, demonstrated that (1) the secreted apoA-IV associated mainly with high-density lipoproteins (HDLs) and only a trace amount of apoA-IV was associated with very-low-density lipoproteins; (2) overexpression of apoA-IV resulted in an increased number of disk-shaped structures (thickness, approximately 8.0 nm and diameter, approximately 22 nm); and (3) the electrophoretic mobilities of the apoA-IV-containing particles differed from those of apoA-I-containing HDL. Expression of apoA-IV exerted no discernible effect on the density distribution or the secretion efficiency of apoB-100. Additionally, secretion of apoB-100 and apoA-IV exhibited opposite responses to serum: apoB-100 secretion was stimulated eightfold after addition of serum, whereas apoA-IV secretion was inhibited by 40%. These results suggest that synthesis of apoA-IV may lead to the formation of a subclass of HDL with a different metabolic fate than that of lipoproteins containing either apoA-I or apoB.
ApoE4 polymorphism increases the risk for exercise-induced silent myocardial ischemia in older men.
Authors: Katzel L I , Fleg J L , Paidi M , Ragoobarsingh N , Goldberg A P
Published: June 2011

The apolipoprotein (apo) E4 polymorphism is associated with increased risk for symptomatic coronary artery disease (CAD). This study examines whether the apo epsilon allele is associated with an increased risk for exercise-induced silent myocardial ischemia (SI) in healthy, older (62 +/- 7 years; mean +/- SD), normocholesterolemic, nonsmoking male volunteers. The apo epsilon 4 allele was present in 20 of 45 (44%) men with SI on graded exercise treadmill testing compared with 22 of 127 (17%) men of comparable age with normal exercise tests (P < .001), resulting in a crude relative risk of 2.57 (95% confidence limits, 1.57 to 4.23) for SI in men with the apo epsilon 4 allele compared with those without the epsilon 4 allele. Although the lipoprotein lipid levels did not differ between men with normal exercise tests and those with SI, the men with the apoE 4/3 phenotype had higher total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels than those with the apoE 2/3 and 3/3 phenotypes (P < .05). Men with SI and the apoE 4/3 phenotype were older (64 +/- 5 versus 57 +/- 8 years, P < .01) and leaner (P < .01) than the normal non-SI men with the apoE 4/3 phenotype. The older age of the men with SI and the apoE 4/3 phenotype is consistent with a progression of atherosclerosis over time. Men with SI and the apoE 3/3 phenotype were of comparable age and body composition to apoE 3/3 phenotype men with normal exercise tests. Thus, even in the presence of normal LDL-C levels, the apo epsilon 4 allele may predispose older men to SI.
Effects of canola, corn, and olive oils on fasting and postprandial plasma lipoproteins in humans as part of a National Cholesterol Education Program Step 2 diet.
Authors: Lichtenstein A H , Ausman L M , Carrasco W , Jenner J L , Gualtieri L J , Goldin B R , Ordovas J M , Schaefer E J
Published: June 2011

The most stringent dietary recommendations of the National Cholesterol Education Program (NCEP) are to limit fat intake to < 30% of calories, saturated fat intake to < 7% of calories, and cholesterol intake to < 200 mg/d (Step 2 diet). There is debate as to whether the remaining fat in the diet should be relatively high in monounsaturated or polyunsaturated fatty acids. We examined this issue by testing the effects of diets meeting the aforementioned guidelines that were enriched in three different vegetable oils on plasma lipids in the fasting and postprandial states in a clinically relevant population. Female and male subjects (n = 15, mean age, 61 years) with low-density lipoprotein cholesterol (LDL-C) concentrations > 130 mg/dL were studied under strictly controlled conditions. Subjects were first placed on a diet similar to that currently consumed in the United States to stabilize plasma lipids with respect to identical fat and cholesterol intakes. The subjects then received diets meeting NCEP Step 2 criteria in which two thirds of the fat calories were given either as canola, corn, or olive oil in a randomized, double-blinded fashion for 32 days each. Plasma cholesterol concentrations declined after consumption of diets enriched in all the test oils; however, the declines were significantly greater for the canola (12%) and corn (13%) than for the olive (7%) oil-enriched diet. Mean plasma LDL-C concentrations declined after consumption of diets enriched in all the test oils (16%, 17%, and 13% for canola, corn, and olive oil, respectively), and the magnitude of the declines was statistically indistinguishable among the test oils. Mean plasma high-density lipoprotein cholesterol (HDL-C) concentrations declined after consumption of the baseline diet, and these declines were significant for the canola (7%) and corn (9%) oil-enriched diets. Changes in LDL apolipoprotein (apo)B concentrations paralleled those of LDL-C. Switching from the baseline to the vegetable oil--enriched diets had no significant effect on plasma triglyceride, apoA-I, and lipoprotein(a) concentrations or the total cholesterol to HDL-C ratio. LDL apoB to apoA-I ratios were significantly reduced when the subjects consumed the vegetable oil--enriched diets. Differences similar to those observed in the fasting state were observed in the postprandial state.(ABSTRACT TRUNCATED AT 400 WORDS)
The relation of lipoprotein[a] concentrations and apolipoprotein[a] phenotypes with asymptomatic atherosclerosis in subjects of the Atherosclerosis Risk in Communities (ARIC) Study.
Authors: Brown S A , Morrisett J D , Boerwinkle E , Hutchinson R , Patsch W
Published: June 2011

Plasma levels of lipoprotein[a] (Lp[a]) are associated with increased risk of coronary artery disease and show an inverse correlation with apolipoprotein[a] (apo[a]) molecular weight. We determined Lp[a] levels and apo[a] phenotypes in 171 cases with preclinical extracranial carotid atherosclerosis as ascertained by B-mode ultrasound and in 274 control subjects free of carotid atherosclerosis. Lp[a] protein levels measured by enzyme-linked immunosorbent assay ranged from 4 to 361 micrograms/mL in cases and from 2 to 392 micrograms/mL in controls, but median levels of Lp[a] were higher in cases than in controls (51 micrograms/mL versus 33 micrograms/mL, P < .003). In both groups, all 11 apo[a] polymorphs that are resolved by the procedure used were present, resulting in 43 and 39 different apo[a] phenotypes in cases and controls, respectively. An inverse relation between apo[a] polymorph size and Lp[a] level was observed in both cases (r = -0.49, P < .001) and controls (r = -0.34, P < .001). Apo[a] phenotype distributions were similar in cases and controls. However, in 17 phenotypes with three or more subjects per group, the difference of mean Lp[a] concentrations between cases and controls was 32 +/- 36 micrograms/mL (mean +/- SD). Thus, the higher Lp[a] levels in cases were not associated with a greater prevalence of small apo[a] polymorphs. Stepwise logistic regression analyses of known risk factors for coronary heart disease showed that plasma Lp[a] concentration was an independent predictor of case-control status, while Lp[a] phenotype was not, irrespective of the presence or absence of Lp[a] concentration in the model.(ABSTRACT TRUNCATED AT 250 WORDS)
Associations of age, adiposity, alcohol intake, menstrual status, and estrogen therapy with high-density lipoprotein subclasses.
Authors: Williams P T , Vranizan K M , Austin M A , Krauss R M
Published: June 2011

We used nondenaturing polyacrylamide gradient gel electrophoresis to examine the associations of age, adiposity, alcohol intake, and exogenous estrogen with high-density lipoprotein (HDL) subclasses in 427 members of 51 principally Mormon kindreds. The absorbency of protein stain was used as an index of mass concentrations at intervals of 0.01 nm within five HDL subclasses: HDL3c (7.2 to 7.8 nm), HDL3b (7.8 to 8.2 nm), HDL3a (8.2 to 8.8 nm), HDL2a (8.8 to 9.7 nm), and HDL2b (9.7 to 12 mm). Age and alcohol intake were obtained from questionnaires, and body mass index was computed from clinic measurements as weight (kg)/height (m)2. The results suggest that HDL3b concentrations were higher after menopause than before. Adult men (> or = 18 years old) had significantly higher HDL3c and HDL3b and significantly lower HDL2b and HDL2a levels than younger boys. Compared with the women, adult men had higher levels of HDL3c and HDL3b and lower levels of HDL2b, HDL2a, and larger-diameter HDL3a particles. There were no significant differences between the HDL profiles of women and younger boys, suggesting that divergence in HDL occurs during puberty. Eighty-eight percent of the increase in HDL associated with estrogen replacement in postmenopausal women occurred within HDL3a and HDL2a. Reported alcohol intake in adult men correlated with two HDL regions: one within the HDL2b region and a second within the HDL3a/2a region, whereas in women the positive correlation between alcohol and HDL levels was within the HDL2b region only. In both men and premenopausal adult women, increasing levels of body mass index were associated with higher levels of HDL3b and lower levels of HDL2b.(ABSTRACT TRUNCATED AT 250 WORDS)
Cyclic AMP suppresses fibronectin expression in the rabbit aorta in vitro.
Authors: Coats W D , Brecher P
Published: June 2011

The effect of cAMP on the in vitro expression of rabbit aortic fibronectin was examined using a previously characterized organ culture system. Elevation of intracellular cAMP in incubated aortic rings by use of forskolin or dibutyryl cAMP (dbcAMP) inhibited the normally observed increase in fibronectin mRNA to levels below that found in unincubated tissue. The effect of dbcAMP on fibronectin mRNA was dose dependent and reversible. dbcAMP did not affect overall protein biosynthesis or the changes in collagen or elastin mRNAs that normally occurred during in vitro incubation, suggesting a selective regulatory effect on fibronectin. The inhibitory effect of dbcAMP on steady-state fibronectin mRNA levels was independent of the dibutyrate moiety, was not a result of cytotoxicity, did not require de novo protein synthesis, and did not appear to occur through a protein kinase A pathway. The data suggested that suppression of fibronectin mRNA levels potentially occurred via an indirect mechanism that may have involved a dbcAMP-induced reduction in intracellular calcium ([Ca2+]i) levels. The resultant decrease in [Ca2+]i may have affected fibronectin expression via a reduction in protein kinase C activity but did not depend on a calmodulin or calmodulin kinase I or II mechanism.
Severity of peripheral atherosclerosis is associated with fibrinogen and degradation of cross-linked fibrin.
Authors: Lassila R , Peltonen S , Lepäntalo M , Saarinen O , Kauhanen P , Manninen V
Published: June 2011

Immunohistochemical studies of human atherosclerotic lesions have demonstrated the occurrence of fibrin deposition and its degradation in the arterial wall. We studied fibrinogen, the generation of thrombin, and the degradation of fibrin in 40 patients with stable peripheral arterial occlusive disease of varying severity, as assessed by the ankle/brachial pressure index and duplex ultrasonography and/or angiography. Circulating fibrinogen (functional and immunological), fibrinopeptide A, thrombin-antithrombin III complex, and D-dimer were measured. The severity of atherosclerosis was associated with both fibrinogen (both functional and immunological) and D-dimer (r = .57, P < .0002, and r = .57, P < .0001, respectively). Fibrinogen and D-dimer showed a significant positive correlation (r = .50, P < .001). Generation of thrombin was detected in 24 patients (60%) by fibrinopeptide A and levels of thrombin-antithrombin III complex. As a sign of coagulation activation and fibrinolysis, we found that thrombin-antithrombin III complex and the degradation of cross-linked fibrin were progressively associated with the extent of vascular disease. The plasmin-mediated fibrin breakdown contributed to increased levels of circulating fibrinogen, an established risk factor for thrombotic complications. The significant correlations between fibrinogen/D-dimer and the severity of atherosclerosis support previous pathological studies and imply that local degradation of cross-linked fibrin is involved in the progression of atherosclerosis.
Influence of triacylglycerol biosynthesis rate on the assembly of apoB-100-containing lipoproteins in Hep G2 cells.
Authors: Borén J , Rustaeus S , Wettesten M , Andersson M , Wiklund A , Olofsson S O
Published: June 2011

Apolipoprotein B-100 (apoB-100) appears in three forms in the endoplasmic reticulum of Hep G2 cells: (1) tightly bound to the membrane, ie, not extractable by sodium carbonate. This form is glycosylated but protease sensitive when present in intact microsomes, suggesting that it is only partially translocated to the microsomal lumen; (2) extractable by sodium carbonate and present on low-density lipoprotein-very-low-density lipoprotein (LDL-VLDL)-like particles. This form is glycosylated and secreted into the medium; and (3) extractable by sodium carbonate but having a higher density than the LDL-VLDL-like particles. This form, referred to as Fraction I, is glycosylated and protected against proteases when present in intact microsomal vesicles, indicating that it is completely translocated to the luminal side of the microsomal membrane. Fraction I is not secreted into the medium, but it disappears with time from the cell, suggesting that it is degraded. Oleic acid induced a 2.7-fold increase in the rate of the biosynthesis of triacylglycerol but not of phosphatidylcholine in Hep G2 cells. Incubation of the cells with oleic acid had no significant effect on the rate of initiation of the apoB-100-containing lipoproteins, nor did it influence the amount of apoB-100 that was associated with the membrane or the turnover of apoB-100 in the membrane. Instead, it increased the proportion of the nascent apoB polypeptides on initiated lipoproteins that was converted into full-length apoB-100 on LDL-VLDL-like particles, giving rise to an increased amount of these particles in the lumen of the secretory pathway. Pulse-chase experiments showed that incubation with oleic acid gave rise to an increased formation of LDL-VLDL-like particles on behalf of the formation of Fraction I. This effect of oleic acid could partially explain the protective effect of the fatty acid on apoB-100, preventing it from undergoing posttranslational degradation.
Effect of pravastatin and omega-3 fatty acids on plasma lipids and lipoproteins in patients with combined hyperlipidemia.
Authors: Contacos C , Barter P J , Sullivan D R
Published: June 2011

This study compared the effects of a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, fish oil, and placebo on plasma lipids and lipoproteins in patients with mixed hyperlipidemia. After an initial run-in phase, 32 patients were randomized for 6 weeks to either (1) pravastatin 40 mg/d, n = 10; (2) fish oil (himega 6 g/d, equivalent to 3 g omega-3 fatty acids/d), n = 10; or (3) placebo. After single drug therapy, in the pravastatin group mean total plasma cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and apolipoprotein (apo) B fell significantly by 23% (P < .001), 30% (p < .001), and 26% (P < .01), respectively. LDL Stokes' diameter did not change. In the fish oil group mean plasma triglycerides (TG) fell 30% (P < .05), LDL Stokes' diameter increased from 25.0 to 25.9 nm (P < .05), and there was a nonsignificant increase in LDL-C. There were no changes in the placebo group. To assess the effect of the combination of pravastatin plus fish oil therapy, all patients, except one woman from the placebo group who developed nausea on fish oil, then took combined therapy of pravastatin 40 mg/d plus fish oil 6 g/d for an additional 12 weeks. In each case, there were no clinically significant episodes of muscle tenderness or elevation of creatine phosphokinase or alanine aminotransferase. After 12 weeks of combined therapy of pravastatin plus fish oil, there were significant reductions in the mean TC, TG, LDL-C, and apoB in the three groups compared with baseline levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Influence of probucol on enhanced LDL oxidation after fish oil treatment of hypertriglyceridemic patients.
Authors: Lussier-Cacan S , Dubreuil-Quidoz S , Roederer G , Leboeuf N , Boulet L , de Langavant G C , Davignon J , Naruszewicz M
Published: June 2011

The susceptibility of low-density lipoprotein (LDL) to oxidation was studied in hypertriglyceridemic men (5 with type III and 5 with type IV) at baseline on a low-saturated-fat, low-cholesterol diet, after 6 weeks of dietary supplementation with fish oil (Promega, 12 g/d), and after 6 weeks of fish oil combined with probucol (500 mg BID). The relative content of n-3 polyunsaturated fatty acids in plasma and LDL was increased during the two treatment periods, and a low alpha-tocopherol to n-3 polyunsaturated fatty acids ratio was observed. Plasma thiobarbituric acid-reactive substances (TBARS) levels were unchanged after 6 weeks of fish oil, but the ratio of lipid peroxides to the reduced triglyceride (TG) levels (MDA:TG) was significantly higher (P < .01). Addition of probucol lowered both absolute levels of TBARS (P < .01) and the MDA to TG ratio (P < .001). The susceptibility of LDL to Cu(2+)-catalyzed oxidation was evaluated over a 5-hour time course by determining TBARS formation, free amino group levels, and changes in LDL electrophoretic mobility. TBARS levels that were higher in native LDL (1.019 < d < 1.050 g/mL) after 6 weeks of fish oil than at baseline (P < .01) were reduced 52.3 +/- 11.3% by the addition of probucol (P < .001). With fish oil alone, TBARS production after exposure of LDL to Cu2+ for 5 hours was increased 17.0 +/- 5.8% compared with corresponding baseline values (P < .001), whereas a 64.1 +/- 14.3% reduction from the previous period was observed with fish oil + probucol (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)