bluuebunny/crossref_metadata_2025 huggingface dataset:
In vivo effect of insulin on the acute proliferative response of the rat aorta to injury.
Authors: Ridray S , Ktorza A , Picon L , Capron L
Published: June 2011

The objective of our study was to investigate the effect of hyperinsulinemia associated with either euglycemia, hypoglycemia, or hyperglycemia on the short-term mitotic activity of arterial smooth muscle cells (SMCs) after aortic injury. The proliferative reaction of arterial SMCs was provoked by the passage of an embolectomy catheter with a tightly inflated balloon. DNA synthesis was measured as DNA specific activity after incubation of the aorta in a medium containing 3[H]thymidine. Unrestrained rats were rendered hyperinsulinemic (4-7 nM versus 0.3 nM in controls) immediately after aortic injury by insulin infusion (10 units/day) and either euglycemic (about 5.6 mM), hyperglycemic (14-17 mM), or hypoglycemic (about 2.8 mM) by adjusting the flow rate of hypertonic glucose (30% wt/vol) that was infused simultaneously. The infusion was performed via a catheter inserted into the jugular vein and lasted 2 or 4 days after the aortic injury. After the injury, SMC mitotic activity was dramatically increased on day 2 in control rats with deendothelialized aortas and declined between days 2 and 4. In euglycemic-hyperinsulinemic and hyperglycemic-hyperinsulinemic rats, SMC proliferation showed the same pattern as in controls. At no time was a significant difference observed among the three groups of rats. In hypoglycemic-hyperinsulinemic rats, SMC mitotic activity increased to a lesser extent than in controls on day 2 after deendothelialization. These data indicate that hyperinsulinemia with or without hyperglycemia does not stimulate the early stages of arterial SMC proliferation in the rat although a long-lasting effect of hyperinsulinemia cannot be excluded.(ABSTRACT TRUNCATED AT 250 WORDS)
Docosahexaenoic and eicosapentaenoic acids in plasma phospholipids are divergently associated with high density lipoprotein in humans.
Authors: Bønaa K H , Bjerve K S , Nordøy A
Published: June 2011

The effect of fish oil rich in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids on serum lipoprotein concentrations is not clear, and it is not known whether EPA and DHA are similarly related to serum lipid or lipoprotein levels. We conducted a randomized, 10-week, dietary supplementation trial in which the effects of 6 g per day of 85% EPA and DHA were compared with 6 g per day of corn oil in 156 men and women. Multivariate analyses were used to assess independent relations between plasma phospholipid EPA and DHA and serum lipoprotein levels. In the fish oil group triglycerides fell 21% (p less than 0.001) and high density lipoprotein cholesterol (HDL-C) rose 3.8% (p less than 0.05). In the corn oil group triglycerides did not change, but HDL-C rose 6.1% (p less than 0.01). Compared with fish oil, apolipoprotein A-I (apo A-I) rose 5.1% after corn oil intake (p less than 0.05). Plasma EPA and DHA levels rose after fish oil intake and fell after corn oil intake (all p less than 0.001). The change (delta) in EPA was inversely correlated with delta triglycerides (p = 0.035) and positively correlated with delta HDL-C and delta apo A-I (both p less than 0.001) in the multivariate analyses. In contrast, delta DHA was not correlated with delta triglycerides but was inversely correlated with delta HDL-C and delta apo A-I (both p less than 0.001). Standardizing for DHA removed the difference in apo A-I levels between groups. This study suggests that EPA and DHA are divergently associated with HDL, possibly through different mechanisms.
Delivery of passivating proteins to sutures during passage through the vessel wall reduces subsequent platelet deposition by blocking fibrinogen adsorption.
Authors: Johnson P C , Garrett K O , Brash J L , Cornelius R M , Kaplan S S , Warty V
Published: June 2011

Intraluminal vascular suture material, which attracts fewer than the expected number of platelets compared with the same biomaterial exposed to blood in vitro, differs from the untreated biomaterial in that it has been passed once through the vessel wall. The mechanism by which this apparently trivial maneuver reduces platelet deposition was investigated. Polypropylene suture (7-0 Prolene) was passed through human arteries (fetal and adult), and platelet deposition to the suture was measured in a standardized perfusion chamber. Single vessel passage of the sutures reduced platelet deposition by 68 +/- 23%, which contrasts sharply with the power of prostaglandin E1 (1 microM PGE1 is sufficient to abolish platelet shape change and aggregation), which inhibited only 11% of platelet deposition to the sutures. Aspirin treatment of the vessel (to prevent PGI2 formation) or endothelial stripping (to remove the ability to produce nitric oxide) had no effect on the degree of inhibition. Passage of the suture through a vessel analogue (expanded polytetrafluoroethylene) did not inhibit platelet deposition. 125I-fibrinogen adsorption to the suture after vessel passage was reduced to a degree similar to that of platelet deposition. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins eluted from vessel-passed sutures revealed bands at 66, 47, and 16 kd. Western blotting indicated the presence of large amounts of albumin and hemoglobin, a moderate amount of haptoglobin, and only trace amounts of fibrinogen. When sutures were exposed to each of these proteins in vitro before perfusion, albumin and hemoglobin were found to reproduce the effect of vessel passage alone on platelet deposition. We conclude that albumin and hemoglobin adsorb to sutures during their passage through the vessel subendothelium.(ABSTRACT TRUNCATED AT 250 WORDS)
Characterization of deletions in the LDL receptor gene in patients with familial hypercholesterolemia in the United Kingdom.
Authors: Sun X M , Webb J C , Gudnason V , Humphries S , Seed M , Thompson G R , Knight B L , Soutar A K
Published: June 2011

A sample of 200 patients with a clinical diagnosis of heterozygous (189) or homozygous (11) familial hypercholesterolemia (FH) attending lipid clinics in the London area have been screened for the presence of major gene defects in the low density lipoprotein (LDL) receptor gene by Southern blotting of genomic DNA with specific probes. This study is part of a project to determine the frequency of known mutations in the LDL receptor gene in this population. A new polymorphism for the enzyme Bgl II was identified by hybridization with a probe specific for the promoter plus exon 1 of the LDL receptor gene. The observed frequency of the rare allele, characterized by a Bgl II fragment of 13 kb compared with 10 kb for the common allele, was 0.08 in this group of FH patients. Several individuals who were heterozygous for the rare allele were also heterozygous for a mutation elsewhere in the LDL receptor gene that is known to cause FH. Eight different mutations, seven deletions and one duplication, were detected in a total of nine patients, accounting for 4.5% of the mutant alleles in this group. Three of the mutations are apparently identical to deletions that have been described previously in FH patients of British or European origin, while the remaining five have not been described. Two of these were in patients of Polish and Asian Indian origin, while the other three were in patients of apparently British ancestry.
Accelerated cholesterol accumulation in homologous arterial transplants in cholesterol-fed rabbits. A surgical model to study transplantation atherosclerosis.
Authors: Hjelms E , Stender S
Published: June 2011

Accelerated coronary artery disease has become a major complication to heart transplantation in humans. Therefore, we have developed a surgical model in the rabbit, with transplantation of the thoracic aorta as a bypass graft onto the abdominal aorta of another rabbit. The model permits the study of cholesterol metabolism in transplanted arteries. The graft did not accumulate cholesterol for as long as 298 days, provided that the rabbits were normocholesterolemic, i.e., with plasma cholesterol levels of 0.3-0.7 mmol/l. However, after a few weeks of cholesterol feeding resulting in plasma cholesterol levels of 2-5 mmol/l, the homologous graft accumulated cholesterol compared with intact aortic tissue in the rabbits and also compared with autologous aortic grafts. The intimal clearance of plasma cholesteryl ester, mainly high density lipoprotein cholesteryl ester, in the luminal layer of the aortic graft was 60-150 nl x cm-2 x hr-1 1-2 hours after transplantation. The intimal clearance in the corresponding intact thoracic aorta of the recipient animal was 5-20 nl x cm-2 x hr-1. The values were 1,500-3,000 nl x cm-2 x hr-1 51-298 days after transplantation, while the intimal clearance of the rabbit's own aorta remained unchanged. A pronounced increase in plasma lipoprotein permeability is thus an early event in transplanted arteries. It results in a higher cholesteryl ester influx that leads to cholesterol accumulation in the artery, but only if the rabbits are fed a cholesterol-enriched diet. This rabbit model may be useful in the search for interventional measures to prevent or diminish the accelerated coronary artery disease in transplanted hearts in humans.
Selective factor Xa inhibition by recombinant antistasin prevents vascular graft thrombosis in baboons.
Authors: Schaffer L W , Davidson J T , Vlasuk G P , Dunwiddie C T , Siegl P K
Published: June 2011

A baboon model of high-shear, platelet-dependent vascular graft thrombosis was used to assess the antithrombotic effect of recombinant antistasin (rATS), a 119-amino acid protein with selective, subnanomolar inhibitory potency against coagulation factor Xa. In this model, a Dacron vascular graft segment of a femoral arteriovenous (AV) shunt provided the thrombogenic stimulus. Antithrombotic efficacy of rATS was assessed by continuous monitoring of 111In-labeled platelet and 125I-labeled fibrin(ogen) deposition onto the graft surface and blood flow through the vascular shunt. Systemic intravenous administration of rATS (2 or 4 micrograms/kg.min-1) dose dependently decreased both platelet and fibrin(ogen) deposition onto the graft. Vascular graft thrombus formation was completely inhibited at a systemic dose of rATS of 4 micrograms/kg.min-1. None of the AV shunts in animals receiving rATS at either dose occluded, and blood flow was maintained at 81 +/- 4% (2 micrograms/kg.min-1 rATS) or 96 +/- 3% (4 micrograms/kg.min-1 rATS) of basal flow. Systemic fibrinopeptide A elevations in response to exposure to the Dacron graft segment were completely suppressed by both doses of rATS. The ex vivo activated partial thromboplastin times were extended to greater than 150 seconds during infusion of both doses of rATS; however, even at fully antithrombotic doses, template bleeding times were not significantly increased. Thus, in this baboon model, rATS is a potent antithrombotic agent that inhibits both platelet and fibrin(ogen) deposition onto a Dacron vascular graft segment. Furthermore, these results demonstrate that selective inhibition of coagulation factor Xa by rATS can completely prevent vascular graft thrombus formation without significantly compromising primary hemostasis as measured by template bleeding time.
Normal postprandial lipemia in men with low plasma HDL concentrations.
Authors: Cohen J C , Grundy S M
Published: June 2011

To examine the relation between postprandial lipemia and high density lipoprotein (HDL) concentrations, we measured the plasma triglyceride and retinyl palmitate responses to 50-g fat meals of 1) 25 men with low HDL cholesterol concentrations (less than 36 mg.dl-1) and normal fasting triglyceride concentrations, 2) 25 men with normal HDL cholesterol (greater than 40 mg.dl-1) and normal fasting triglyceride concentrations, and 3) 20 men with mild to moderate fasting hypertriglyceridemia (250-347 mg.dl-1). The average magnitude of postprandial lipemia induced by the fat meals was markedly higher in the hypertriglyceridemic men (593 +/- 311 mg.dl-1.8 hr) than in either of the normolipidemic groups. In normotriglyceridemic men with low HDL cholesterol, mean postprandial lipemia (303 +/- 158 mg.dl-1.8 hr) was similar to the corresponding value of men with normal HDL (283 +/- 130 mg.dl-1.8 hr). Postprandial plasma retinyl palmitate concentrations, which reflect chylomicron remnant metabolism, also were similar in normal-HDL and low-HDL groups. These data suggest that defects in chylomicron-triglyceride clearance that give rise to excess postprandial lipemia are not a common occurrence in normolipidemic men with low HDL cholesterol concentrations. Accordingly, the low HDL cholesterol concentrations measured in the normotriglyceridemic men in this study must be attributable to factors other than an exaggerated postprandial lipemia.
Autoradiographic analysis of the distribution of 125I-tyramine-cellobiose-LDL in atherosclerotic lesions of the WHHL rabbit.
Authors: Rosenfeld M E , Carew T E , von Hodenberg E , Pittman R C , Ross R , Steinberg D
Published: June 2011

It is well established that plasma lipoproteins enter the artery wall and play a role in the atherogenic process. However, it is still unclear where within developing atherosclerotic lesions lipoproteins accumulate and which arterial cells participate in the metabolism of these lipoproteins. For this reason, light and electron microscopic autoradiograms were prepared from sections of lesioned aortas of Watanabe heritable hyperlipidemic (WHHL) rabbits 44 hours after injection of 125I-tyramine cellobiose-low density lipoprotein (TC-LDL). After uptake of 125I-TC-LDL and intracellular degradation of the LDL protein, the nondegradable TC ligand remains trapped and thus demarcates the cells participating in the degradation of LDL. Results of other studies indicate that 48 hours after injection into WHHL rabbits, about one half of the 125I label present in lesions represents accumulated degradation products while the remaining 125I label is present as intact 125I-TC-LDL. The distribution of autoradiographic silver grains was analyzed at low resolution in fatty streaks, transitional lesions, and advanced atheroma. In all cases, the majority of silver grains were associated with superficially located subendothelial macrophage-derived foam cells. In more advanced lesions, labeling was predominant in foam cells situated within the lateral margins of the lesions. Morphometric quantification of the distribution of silver grains in electron photomicrographs of fatty streaks from two young WHHL rabbits strongly supported the data obtained at the light microscopic level. In early fatty streaks from the aortic arch and the thoracic and abdominal aortas, subendothelial macrophage-derived foam cells contained a high proportion of the silver grains (40-60% of the total) and accounted for between 30% and 40% of the lesion volume. In contrast, smooth muscle cells in the lesions contained only 7-10% of the total silver grains and accounted for approximately 20% of the lesion volume. Endothelial cells contained the most silver grains on a per-unit-volume basis by occupying only 1-2% of the lesion volume. However, the endothelium contained less than 5% of the total grains in lesions. The remaining silver grains (25-45%) were associated with the extracellular matrix, which constituted between 40% and 50% of the lesion volume. These data indicate that in the WHHL rabbit, subendothelial macrophage-derived foam cells avidly accumulate and metabolize LDL despite having few functional LDL receptors.
Inhibition of leukocyte extravasation with a monoclonal antibody to CD18 during formation of experimental intimal thickening in rabbit carotid arteries.
Authors: Kling D , Fingerle J , Harlan J M
Published: June 2011

In the rabbit model of electrically induced intimal thickening, the adherence processes of different leukocyte subsets as well as the functional significance of leukocyte invasion in the initial migration of smooth muscle cells (SMCs) into the intima were studied by using monoclonal antibody (MAb) 60.3 (directed to the leukocyte adherence glycoprotein CD18), a known potent inhibitor of leukocyte adhesive functions. In control carotid arteries exposed to two periods of electrical stimulation within 36 hours, leukocytes, including all granulocyte subsets, monocytes, and lymphocytes, invaded the cell-free subendothelium. Concomitantly, SMCs were observed to migrate from the media into the intima. In the MAb 60.3-treated rabbits, however, neutrophil emigration into the stimulated arteries was abolished, whereas mononuclear leukocyte accumulation in the intima was only partially inhibited, indicating a complete CD18-dependent mechanism for neutrophil extravasation and additional receptor-ligand systems for the emigration of mononuclear leukocytes. SMCs moved into the intima despite complete blockage of neutrophils and the reduced accumulation of mononuclear cells within the subendothelium after MAb administration. These results preclude neutrophils as initiators of SMC migration into the intima. The influence of mononuclear cells on the migratory behavior of SMCs in intimal thickening formation, however, needs further elucidation.
Insulin resistance in familial and nonfamilial hypercholesterolemia.
Authors: Karhapää P , Voutilainen E , Kovanen P T , Laakso M
Published: June 2011

High levels of very low density lipoprotein triglycerides and low levels of high density lipoprotein cholesterol have been found to be associated with insulin resistance measured by the euglycemic clamp technique. In contrast, the association of isolated hypercholesterolemia with insulin resistance has not been systematically studied. Therefore, we performed two separate studies designed to investigate the degree of insulin resistance in familial hypercholesterolemia (FH) (study 1) and nonfamilial hypercholesterolemia (non-FH) (study 2). Study 1 included eight young adults with FH and 13 corresponding control subjects. Fasting blood glucose, insulin, and C-peptide levels were similar in FH patients and control subjects during an oral glucose tolerance test. During the euglycemic hyperinsulinemic (1,200-1,300 pmol/l) clamp studies, FH patients and control subjects had similar rates of whole-body glucose uptake (73 +/- 6 versus 70 +/- 3 mumol/kg per minute, respectively; p = NS). Glucose oxidation, glucose nonoxidation, lipid oxidation, suppression of free fatty acid levels, and potassium disposal were similar in both groups. Study 2 included 25 middle-aged non-FH patients and 18 corresponding control subjects. Glucose, insulin, and C-peptide responses in an oral glucose tolerance test were similar in both groups. During the euglycemic hyperglycemic clamp studies, non-FH patients and control subjects had similar rates of whole-body glucose uptake (61 +/- 3 versus 58 +/- 3 mumol/kg per minute, p = NS). In addition, glucose oxidation, glucose nonoxidation, lipid oxidation, and suppression of free fatty acid levels as well as potassium disposal were similar in non-FH patients and control subjects. We conclude that FH and non-FH are not insulin-resistant states.
Serum lipoproteins and hemostatic function in intermittent claudication.
Authors: Johansson J , Egberg N , Johnsson H , Carlson L A
Published: June 2011

Normoglucemic men with intermittent claudication (n = 41), mean age of 63 years, and sex-, age-, body mass index-, and smoking habit-matched controls (n = 75) were compared for plasma lipoprotein and hemostatic variables. The patients had significantly lower levels of large high-density lipoprotein (HDL) particles (HDL2b, HDL2a, and HDL3a) and elevated lipoprotein(a) [Lp(a)] concentrations than the control subjects. Of the hemostatic variables, plasminogen activator inhibitor-1 (PAI-1), plasma antiplasmin, plasma fibrinogen, and urine beta-thromboglobulin concentrations were significantly elevated in patients. In intermittent claudication patients Lp(a) correlated significantly with activation of the coagulation system, ie, with the levels of plasma fibrinogen and urine fibrinopeptide A. No correlations between the values for Lp(a) and PAI-1 or plasma alpha 2-antiplasmin were seen. The PAI-1 activity showed significant univariate correlations to the levels of HDL3b, HDL2b (inverse), and very-low-density lipoprotein triglycerides, of which the positive correlation to HDL3b persisted in multivariate analysis (r = .48, P < .001). Independent characteristics for intermittent claudication estimated by multiple regression analysis were PAI-1, plasma fibrinogen, and HDL3a, with a combined R2 of .36. The intermittent claudication subgroup that was being treated with beta-blockers/thiazides had a higher frequency of coronary heart disease compared with the other patients. In addition, the patients taking beta-blockers/thiazides had elevated triglyceride concentrations, lower HDL cholesterol with a size shift toward smaller particles, and a tendency toward raised PAI-1 and plasma alpha 2-antiplasmin levels compared with the patient group that did not take these medications.
Retinoids stimulate ApoA-I synthesis by induction of gene transcription in primary hepatocyte cultures from cynomolgus monkey (Macaca fascicularis)
Authors: Kaptein A , de Wit E C , Princen H M
Published: June 2011

The influence of different retinoids on apolipoprotein A-I (apoA-I) synthesis and secretion was investigated in primary monolayer cultures of hepatocytes from cynomolgus monkeys. Addition of retinol (vitamin A) and retinoic acid to the culture medium resulted in a time- and dose-dependent increase in the secretion of apoA-I. No effect was observed during the first 24-hour incubation period; however, apoA-I secretion was enhanced 1.5-fold in the following 24-hour period in the presence of 10 mumol/L retinoic acid. Maximal stimulation (2.7-fold) was obtained at 10 mumol/L retinoic acid during a third 24-hour incubation. In these experiments apoB-100 secretion was unaffected. When [35S]methionine incorporation studies were performed de novo synthesis of apoA-I was increased, whereas total protein synthesis remained constant. These observations indicated that the induction of apoA-I synthesis is not part of a general effect of retinoic acid on hepatic protein synthesis. Among different natural and synthetic retinoids, retinoic acid and its 9-cis and 13-cis isomers were equally active and were the most potent inducers of apoA-I synthesis, whereas the maximal stimulation induced by retinol was lower (1.6-fold). ApoA-I mRNA abundance was increased threefold in hepatocytes exposed for 72 hours to 10 mumol/L retinoic acid, which was associated with a twofold increase in the transcriptional rate of the apoA-I gene. In contrast, no changes were found in the apoB-100 mRNA level and transcriptional activity of the apoB-100 gene. We conclude that retinoids enhance apoA-I synthesis in simian hepatocytes by transcriptional regulation.
A cross-sectional study of endogenous tissue plasminogen activator, total cholesterol, HDL cholesterol, and apolipoproteins A-I, A-II, and B-100.
Authors: Ridker P M , Vaughan D E , Stampfer M J , Sacks F M , Hennekens C H
Published: June 2011

Elevated levels of endogenous tissue-type plasminogen activator (t-PA) appear to be a marker for preclinical atherosclerosis. At present, however, data describing potential relations between plasma t-PA level and established lipid risk factors for coronary atherosclerosis are sparse. To explore these potential relations, we measured plasma levels of t-PA antigen (t-PA:ag) in 633 apparently healthy men in the Physicians' Health Study as well as total cholesterol, high-density lipoprotein (HDL) cholesterol, HDL2 cholesterol, HDL3 cholesterol, and apolipoproteins A-I, A-II, and B-100. Overall, plasma t-PA:ag levels were inversely correlated with HDL cholesterol (r = -.1616, P < .0005), HDL2 cholesterol (r = -.1632, P < .0005), and HDL3 cholesterol (r = -.0927, P = .019). In stratified analyses, the inverse association between t-PA:ag and HDL cholesterol was present among frequent (P trend = .002) and infrequent (P trend = .004) consumers of alcohol as well as among the subgroups of frequent exercisers (P trend < .001), men in the lower half of body mass index (P trend = .001), and nonsmokers (P trend < .001). In contrast, there was no association between t-PA:ag and total cholesterol (r = .0219, P = .58), whereas relations of t-PA:ag with apolipoproteins A-I, A-II, and B-100 were minimal and of borderline significance. These data indicate that plasma levels of endogenous t-PA:ag are inversely related to HDL cholesterol as well as HDL2 and HDL3 cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)
Comparative study of the activity and composition of HDL3 in Russian and American men.
Authors: Shakhov Y A , Oram J F , Perova N V , Alexandri A L , Kolpakova G V , Marcovina S , Oganov R G , Bierman E L
Published: June 2011

Previous studies conducted within the framework of the Lipid Research Clinics Program showed a strong inverse correlation between high-density lipoprotein cholesterol (HDL-C) level and coronary heart disease (CHD) risk in American male populations, whereas in Russian populations such a correlation was less pronounced. It was assumed that HDL was less protective of CHD in Russian than in American males. This study compared the functional activity and lipid composition of HDL3 isolated from the blood plasma of men with low, normal, and high HDL-C levels from Moscow (Russia) and Seattle (United States) populations. Results obtained showed that American HDL3, irrespective of the plasma HDL-C level, had higher activity in stimulating both [3H]cholesterol and cholesterol mass efflux from cholesterol-loaded fibroblasts and in suppressing cellular cholesterol esterification when compared with Russian HDL3. American HDL3 remained more active than Russian HDL3, even when apolipoprotein E-containing particles were removed from HDL3 by heparin-Sepharose affinity chromatography. Russian and American 125I-HDL3 had similar binding to high-affinity cell-surface sites, but Russian HDL3 had a higher nonspecific binding component compared with American HDL3. This study demonstrates for the first time potential functional differences between HDL particles isolated from Russian and American populations. The lower activity of Russian HDL3 in promoting cellular cholesterol efflux may partly explain the higher CHD risk in the Russian population compared with the American one.
Vitamin E, LDL, and endothelium. Brief oral vitamin supplementation prevents oxidized LDL-mediated vascular injury in vitro.
Authors: Belcher J D , Balla J , Balla G , Jacobs D R , Gross M , Jacob H S , Vercellotti G M
Published: June 2011

In previously reported in vitro studies, we found that heme, a physiologically widespread hydrophobic iron compound, can rapidly generate oxidized low-density lipoprotein (LDL), which then becomes cytotoxic to cultured vascular endothelial cells; both LDL oxidation and endothelial cytotoxicity were inhibited by incubation with exogenous alpha-tocopherol (vitamin E) or ascorbic acid (vitamin C). Seeking relevance to in vivo conditions, we performed a study in which 10 human volunteers were given daily antioxidant supplements of 800 IU of DL-alpha-tocopherol acetate alone or in combination with 1000 mg of ascorbic acid for 2 weeks. LDL resistance to heme oxidation ex vivo, as measured by the lag time for conjugated-diene formation, increased by as much as threefold from a mean +/- SD of 58 +/- 11 to 104 +/- 18 minutes (P < .001); LDL alpha-tocopherol increased from 11 +/- 2 to 26 +/- 6 molecules per LDL particle (P < .001); and most impressively, cytotoxicity to porcine aortic endothelial cells incubated with LDL conditioned with heme plus H2O2 or with copper was completely prevented (cytotoxicity before supplementation was 42 +/- 12%, decreasing after supplementation to 3 +/- 2%, P < .001). These measurements reverted to their presupplement levels within 2 weeks after participants stopped taking antioxidant supplements and were reproduced in 4 subjects taking 800 IU of DL-alpha-tocopherol acetate supplements alone but not in the same subjects taking 1000 mg ascorbic acid supplements alone. In conclusion, oral vitamin E supplementation increases LDL alpha-tocopherol content, increases LDL resistance to oxidation, and decreases the cytotoxicity of oxidized LDL to cultured vascular endothelial cells.
Determination of lipid transfer inhibitor protein activity in human lipoprotein-deficient plasma.
Authors: Morton R E , Steinbrunner J V
Published: June 2011

Lipid transfer protein (LTP) activity is modulated by a distinct plasma protein termed lipid transfer inhibitor protein (LTIP). The objective of this study was to establish an assay for LTIP that could be used to quantify its activity in lipoprotein-deficient plasma. A straightforward heating protocol (56 degrees C for 60 minutes) was found to inactivate more than 90% of LTIP activity. The responses of individual lipoprotein-deficient plasma samples to this heating procedure were unique. Among normolipidemic donors, inactivation of LTIP caused a 230% to 600% increase in LTP activity. Essentially all measurable transfer activity in native and heated samples was inhibited by an antibody to LTP. Whole-plasma samples from these donors were spiked with radiolabeled lipoproteins to measure the rates of lipid transfer among the major lipoprotein classes. In general, plasma lipid transfer rates were negatively correlated with LTIP activity in these samples. However, the decrease in lipid transfers from very-low-density lipoprotein (VLDL) to low-density lipoprotein (LDL) and from LDL to VLDL was from 2.4- to 5.1-fold greater than in the transfers from VLDL to high-density lipoprotein (HDL) or from HDL to VLDL. In these samples, the molecular weight of HDL2 was negatively correlated with LTIP activity. Thus, LTIP activities among normolipidemic individuals were observed to vary severalfold; compared with other lipoprotein transfers, higher LTIP activities were associated with a relative reduction in LDL-VLDL lipid transfer events.
Expression of follistatin, an activin-binding protein, in vascular smooth muscle cells and arteriosclerotic lesions.
Authors: Inoue S , Orimo A , Hosoi T , Matsuse T , Hashimoto M , Yamada R , Ouchi Y , Orimo H , Muramatsu M
Published: June 2011

Activin-A has a mitogenic effect on vascular smooth muscle cells (SMCs) and is produced by monocyte/macrophage lineage cells. Here, we studied the expression of follistatin, an activin-binding protein, in both A10 cells, a rat aortic SMC line, and vascular SMCs derived from adult rat aorta. Follistatin mRNA was detected in these cells by Northern blot analysis. Ligand blot and immunoblot analyses demonstrated that follistatin was produced in the conditioned medium at a higher level by A10 cells than by SMCs. Furthermore, immunostaining and in situ hybridization of the arteriosclerotic lesions showed that follistatin was highly expressed in the diseased artery, where abnormal proliferation of SMCs occurred. We suggest that follistatin is produced by vascular SMCs and is involved in the course of atherogenesis.
Hydrogenation impairs the hypolipidemic effect of corn oil in humans. Hydrogenation, trans fatty acids, and plasma lipids.
Authors: Lichtenstein A H , Ausman L M , Carrasco W , Jenner J L , Ordovas J M , Schaefer E J
Published: June 2011

The effects of plasma lipoproteins and apolipoproteins of replacing corn oil with corn-oil margarine in stick form as two thirds of the fat in the National Cholesterol Education Program (NCEP) Step 2 diet were assessed in 14 middle-aged and elderly women and men (age range, 44-78 years) with moderate hypercholesterolemia (low density lipoprotein cholesterol [LDL-C] range, 133-219 mg/dl [3.45-5.67 mmol/l] at screening). During each 32-day study phase, subjects received all their food and drink from a metabolic kitchen. Subjects were first studied while being fed a diet approximating the composition of the current US diet (baseline), which contained 35% of calories as fat (13% saturated fatty acids [SFAs], 12% monounsaturated fatty acids [MUFAs; 0.8% 18:1n-9 trans], and 8% polyunsaturated fatty acids [PUFAs]) and 128 mg cholesterol/1,000 kcal. This baseline phase was followed by a corn oil-enriched diet containing 30% fat (6% SFA, 11% MUFA [0.4% 18:1n-9 trans], and 10% PUFA) and 83 mg cholesterol/1,000 kcal, and then a corn-oil margarine-enriched diet containing 30% fat (8% SFA, 12% MUFA [4.2% 18:1n-9 trans], and 8% PUFA) and 77 mg cholesterol/1,000 kcal. All diets were isocaloric. Mean fasting LDL-C and apolipoprotein (apo) B levels were 153 mg/dl (3.96 mmol/l) and 101 mg/dl on the baseline diet, 17% and 20% lower (both p < 0.001) on the corn oil-enriched diet, and 10% and 10% lower (both p < 0.01) on the margarine-enriched diet.(ABSTRACT TRUNCATED AT 250 WORDS)
Induction of murine macrophage growth by modified LDLs.
Authors: Yui S , Sasaki T , Miyazaki A , Horiuchi S , Yamazaki M
Published: June 2011

We previously reported that cell membrane components and lipoproteins were able to induce the growth of murine peritoneal macrophages. The aim of the present study was to examine whether macrophage growth could also be induced by chemically modified lipoproteins, such as acetylated low density lipoprotein (acetyl-LDL) or oxidized LDL, ligands known to be endocytosed by the macrophage scavenger receptors. When murine peritoneal exudate macrophages were cultured in vitro with 25-100 micrograms/mL acetyl-LDL or oxidized LDL, significant growth was induced. On comparing the dose-response curves of these LDLs, a more potent effect was seen with oxidized LDL than acetyl-LDL, especially on resident macrophages. On the other hand, growth of these cells was not stimulated by native (unmodified) LDL or high density lipoprotein. These in vitro data revealed a new function of chemically modified LDLs as effective inducers of macrophage cell growth. This aspect may be physiologically relevant to the growth of macrophage foam cells in situ in the development of atherosclerosis.
Insulin resistance, glucose intolerance, and hyperinsulinemia. Hypertriglyceridemia versus hypercholesterolemia.
Authors: Sheu W H , Shieh S M , Fuh M M , Shen D D , Jeng C Y , Chen Y D , Reaven G M
Published: June 2011

Plasma glucose and insulin responses to oral glucose and mixed meals and the ability of insulin to stimulate glucose disposal were quantified in normal volunteer subjects and patients with types IIA, IIB, and IV hyperlipoproteinemia (HLP). The results indicated that patients with either type IIB or IV HLP had higher plasma glucose (p < 0.05-< 0.001) and insulin (p < 0.001) responses to both oral glucose and mixed meals compared with the normal subjects and patients with type IIA HLP. Steady-state plasma glucose concentrations (mmol/L) were also higher (p < 0.001) in patients with types IIB (13.3 +/- 0.6) and IV (12.8 +/- 1.2) HLP during a continuous infusion of somatostatin, glucose, and insulin than either the control group (volunteer subjects) (6.2 +/- 0.9) or patients with type IIA HLP (5.6 +/- 1.0). Because the steady-state plasma insulin concentrations were similar in all four groups, patients with either type IIB or IV HLP were resistant to insulin-mediated glucose uptake. These data indicate that patients with hypertriglyceridemia are insulin resistant, glucose intolerant, and hyperinsulinemic, irrespective of the plasma cholesterol concentration. The results further demonstrate that hypercholesterolemic patients with normal triglyceride concentrations do not have any abnormalities of glucose and insulin metabolism.
Cell-derived unesterified cholesterol cycles between different HDLs and LDL for its effective esterification in plasma.
Authors: Huang Y , von Eckardstein A , Assmann G
Published: June 2011

Pulse-chase incubations of human plasma with [3H]cholesterol-laden skin fibroblasts or low density lipoproteins (LDL) and nondenaturing two-dimensional electrophoresis were used to study the transfer and esterification of cell-derived unesterified cholesterol (UC) in human plasma lipoproteins. Specific radioactivities ([3H]UC per microgram of UC) were calculated, and net cholesterol mass transfer was quantified using a fluoro-enzymatic assay to validate productive transfers of UC between high density lipoprotein (HDL) and LDL. Cellular UC was initially taken up by pre-beta 1-HDL and subsequently transferred in the sequence pre-beta 2-HDL-->pre-beta 3-HDL-->alpha-HDL-->LDL. During the first 5 minutes of this process, only 5% of cellular cholesterol was esterified in pre-beta 3-HDL and alpha-HDL; the remainder reached LDL as UC. Cellular UC accumulating in LDL was then redistributed to various HDL particles via two pathways: 1) the partially LDL receptor-mediated uptake and re-secretion of UC by cells and 2) the direct transfer of UC to HDL, mostly to alpha-HDL and a small amount to pre-beta-HDL. UC was not transferred from LDL to HDL after inhibition of lecithin:cholesterol acyltransferase (LCAT). The esterification of cellular [3H]cholesterol in plasma was competitively inhibited by the addition of excess unlabeled LDL but not of excess HDL. However, both excess LDL and excess HDL prevented the esterification of cell-derived cholesterol in apolipoprotein B-free plasma. This demonstrated that LDL is the major source of UC to the LCAT reaction and that the transfer of UC from LDL to HDL is LCAT dependent. In conclusion, the effective esterification of cell-derived cholesterol in plasma involves a rapid transfer of UC via HDL particles to LDL, from which it is distributed to pre-beta-HDL and alpha-HDL. Furthermore, we hypothesize that the transfer per se of cellular UC to LDL forms a cholesterol concentration gradient between cell membranes and HDL and thus a second, reverse cholesterol transport mechanism in addition to the esterification of cholesterol by LCAT.
Comparison of supplementation of RRR-alpha-tocopherol and racemic alpha-tocopherol in humans. Effects on lipid levels and lipoprotein susceptibility to oxidation.
Authors: Reaven P D , Witztum J L
Published: June 2011

It has been suggested that alpha-tocopherol, a safe and effective antioxidant, be used in clinical trials to evaluate the ability of antioxidant therapy to inhibit atherosclerosis. Recent reports, however, have raised the possibility that there may be greater enrichment of plasma low density lipoprotein (LDL) in alpha-tocopherol resulting from the use of the naturally occurring RRR-alpha-tocopherol isomer compared with the other isomers present in the synthetic racemic form of alpha-tocopherol. Therefore, we fed equal dosages (1,600 mg/day) of the two forms of vitamin E to 16 men and women for 8 weeks and compared the effects of this supplementation on the susceptibility of isolated lipoproteins to oxidation. Neither form of vitamin E had appreciable effects on lipid or lipoprotein levels. alpha-Tocopherol levels in LDL increased at a similar rate in both groups and were nearly twofold higher than baseline levels by the end of the study. The susceptibility of LDL to oxidation was measured by formation of conjugated dienes, lipid peroxides, and thiobarbituric acid-reactive substances, as well as by macrophage degradation of LDL exposed to oxidizing conditions in vitro. The susceptibility of LDL to oxidation was decreased in both vitamin E groups compared with the baseline value, and this reduction occurred to a similar extent in both vitamin E-supplemented groups. alpha-Tocopherol levels in LDL also strongly correlated with all measures of LDL oxidation. This study demonstrates that, at this dosage, supplementation with either the natural or synthetic form of alpha-tocopherol provided equal antioxidant protection to LDL.
Substrate delivery as a determinant of hepatic apoB secretion.
Authors: Sniderman A D , Cianflone K
Published: June 2011

The evidence that apoB particles secreted by the liver can differ in number and composition has been reviewed. No evidence has yet emerged that changes in apoB100 itself affect the rate of its secretion from the liver. The metabolic role of apoB appears to be the prevention of lipid accumulation within the liver cell: when delivery of lipid to the liver increases, apoB secretion will increase pari passu. This reality in no way detracts from the critical role played by the LDL receptor in determining the number of LDL particles in plasma, nor does it diminish the potential importance of intracellular processes such as 7 alpha-hydroxylase activity to also mediate LDL receptor activity. However, it should be obvious that variation in catabolism by itself cannot explain all that has been observed in physiological and pathological studies. On the contrary, the whole process must be taken into account--the rate at which apoB particles are added to the circulation, the rate at which they are converted to LDL, and the rate at which they are irreversibly removed from plasma--if we are to understand and appreciate this most peculiar and most important of transport systems.
Development and regression of atherosclerosis in pigs. Effects of n-3 fatty acids, their incorporation into plasma and aortic plaque lipids, and granulocyte function.
Authors: Sassen L M , Lamers J M , Sluiter W , Hartog J M , Dekkers D H , Hogendoorn A , Verdouw P D
Published: June 2011

Fifty-one pigs were fed a low-cholesterol basal diet, to which either 10% (by weight) of lard fat (group INORM, n = 7), 2% cholesterol plus 8% lard fat (group II, n = 33), or 2% cholesterol plus 4% lard fat plus 4% fish oil (group IIIPREV, n = 11) was added. In all pigs, the left anterior descending coronary artery and the abdominal aorta were denuded at 1 month. In the first 24 hours thereafter, three animals in group II and two in group IIIPREV died suddenly. After 3 months, 0.5% bile acids was added to the diet in groups II and IIIPREV. After 8 months the degree of atherosclerosis was evaluated in groups INORM and IIIPREV and in 14 animals from group II (IIIND). At 4 months, one animal from Group II died of pneumonia. For the next 4 months (postinduction period), the remaining 15 animals from group II received the basal diet, to which either 10% lard fat (group IILF, n = 6) or 5% lard fat plus 5% fish oil (group IIFO, n = 9) was added. The hypercholesterolemic diet increased plasma cholesterol from 2 to 9-12 mM after 8 months. Fish oil had no major effects on plasma lipids during both induction and postinduction. Superoxide production by granulocytes in response to the membrane receptor-dependent N-formyl-methionyl-leucyl-phenylalanine (fMLP) gave a higher response in group IIIND than in group INORM. In group IIIPREV, the response to phorbol myristate acetate (PMA) and fMLP was lowered, while in groups IIFO and IILF the responses to PMA and fMLP were not affected. The response to serum-treated zymosan was similar in all groups. Abrasion caused increases in free cholesterol (40%) and phospholipids (46%) in the abdominal aortas of group INORM animals. Hypercholesterolemia increased both free and esterified cholesterol in the entire aorta. Fish oil prevented accumulation of free cholesterol in the nonabraded ascending aorta during induction and further accumulation of free cholesterol and phospholipids in the abdominal aorta during postinduction. In the nonabraded ascending aorta, triglycerides were significantly (almost five times) lower in group IIFO than in group IILF. During both induction and postinduction, a large incorporation of n-3 polyunsaturated fatty acids (up to 20%) occurred in plasma and aortic cholesterol esters and phospholipids of groups IIFO and IIIPREV.(ABSTRACT TRUNCATED AT 400 WORDS)
Relation between sex hormones and serum lipoprotein and lipoprotein(a) concentrations in premenopausal obese women.
Authors: De Pergola G , Giorgino F , Cospite M R , Giagulli V A , Cignarelli M , Ferri G , Giorgino R
Published: June 2011

Lipoprotein(a) (Lp[a]) is generally considered to be a risk factor for the development of cardiovascular disease, but little is known about the possible influence of obesity on the circulating levels of this lipoprotein. The present study was undertaken to examine this aspect in 136 menstrually active women by comparing the serum concentrations of Lp(a) between 72 obese and 64 age-matched nonobese women. Since an adverse effect of androgens and a protective effect of estrogens have been described for plasma lipoprotein profiles in obese women, the relation between the circulating levels of Lp(a) and those of these other hormones was also investigated in obese patients. In addition, other lipoproteins, anthropometric parameters (body mass index and waist-to-hip ratio), and insulin were evaluated. The levels of Lp(a) were not significantly different (Mann-Whitney U test chi 2, 3.59; p = 0.0582 [NS]) between obese (rank sum, 5,367) and control (rank sum, 3,949) women; in addition, the percentage of patients with high Lp(a) levels (cutoff defined at 30 mg/dL) did not differ between the two groups (obese women, 30%; control, 21.8%; chi 2, 0.90; two-sided p = 0.341 [NS]). Moreover, no correlation was found between Lp(a) and body mass index. Lastly, when the Lp(a) prevalence odds ratio for obesity was examined by adjusting the levels of this lipoprotein for age, triglycerides, total cholesterol, and high density lipoprotein cholesterol, the probability value (0.88) was far from significant. In obese women, no correlation was found between the logarithmically transformed Lp(a) concentrations and all the other variables evaluated in the study. In conclusion, the present study shows that the circulating levels of Lp(a) are not influenced by body weight and cardiovascular risk factors commonly associated with obesity, such as enhanced androgenic activity, hyperinsulinemia, adverse lipoprotein profile, and abdominal fat accumulation.
Identification of multiple dense LDL subfractions with enhanced susceptibility to in vitro oxidation among hypertriglyceridemic subjects. Normalization after clofibrate treatment.
Authors: de Graaf J , Hendriks J C , Demacker P N , Stalenhoef A F
Published: June 2011

The influence of different plasma triglyceride concentrations on the heterogeneity of low density lipoprotein (LDL) and on the susceptibility of LDL to copper oxidation was investigated. By density gradient ultracentrifugation, LDL subfractions were isolated from the plasma of 10 normolipidemic control subjects and 12 hypertriglyceridemic patients both before and after clofibrate treatment. In the plasma of control subjects three LDL subfractions were present: LDL1 (d = 1.030-1.033 g/mL), LDL2 (d = 1.033-1.040 g/mL), and LDL3 (d = 1.040-1.045 g/mL). In the plasma of nine moderately hypertriglyceridemic subjects up to five LDL subfractions could be detected: LDL1-LDL3, LDL4 (d = 1.045-1.049 g/mL), and LDL5 (d = 1.049-1.054 g/mL). This polydispersity of LDL was replaced by monodispersity with increasing plasma triglyceride concentrations in three subjects with chylomicronemia, in whom LDL was concentrated in the narrow LDL5 density range. Clofibrate treatment resulted in a lighter LDL subfraction pattern (LDL1-LDL4). In both the control and the moderately hypertriglyceridemic subjects, the small dense LDL subfractions appeared more prone to oxidative modification in vitro than the light LDL subfractions, as measured by the decreased lag time preceding the onset of lipid peroxidation. Furthermore, the dense LDL subfractions were more extensively modified over time, as shown by an increased oxidation rate and a greater number of dienes formed after 6 hours of oxidation. These results suggest an enhanced atherogenic potential of the small, dense LDL subfractions within each LDL subfraction profile. The hypertriglyceridemic LDL subfractions before therapy (LDL3-LDL5) were less resistant to in vitro oxidation than the light, control LDL subfractions (LDL1-LDL3).(ABSTRACT TRUNCATED AT 250 WORDS)