Lovastatin reversed the enhanced sphingomyelin caused by 27-hydroxycholesterol in cultured vascular endothelial cells.

Statins have pleiotropic properties which are involved in inhibiting the thrombogenic response. In this study, the effects of lovastatin on two phospholipids, phosphatidylcholine and sphingomyelin, were studied in cultured endothelial cells in the presence of an oxysterol, 27-hydroxycholesterol. After the cells were cultured with 50 nM of lovastatin for 60 h, lovastatin was found to decrease the incorporation of [H]choline into phosphatidylcholine and sphingomyelin, inhibited CTP: phosphocholine cytidylyltransferase (CT) activity without altering the activity of sphingomyelin synthase and neutral sphingomyelinase.

Effects of trans fats on prostacyclin production.

Objectives: Prostacyclin is a prostanoid derived from arachidonic acid that prevents thrombosis and is thereby expected to protect against heart disease, while trans fats present in partially hydrogenated oils interfere with arachidonic acid metabolism. Therefore, the objective of the present study was to investigate how fats with different proportions of linoleic acid and trans-18:1 affect prostacyclin released by cultured endothelial cells, and to compare these proportions with those found in commercially available foods.

Design: Soybean oil and hydrogenated soybean oil (coating fat) were mixed in different proportions to yield seven fat mixtures with proportions of linoleic acid ranging from 54.

Interaction between sphingomyelin and oxysterols contributes to atherosclerosis and sudden death.

Despite major public health efforts, coronary heart disease continues to be the leading cause of death in the United States. Oxidized lipids contribute to heart disease both by increasing deposition of calcium on the arterial wall, a major hallmark of atherosclerosis, and by interrupting blood flow, a major contributor to heart attack and sudden death. Oxidized cholesterol (oxysterols) enhances the production of sphingomyelin, a phospholipid found in the cellular membranes of the coronary artery.

Effect of curcumin on LDL oxidation in vitro, and lipid peroxidation and antioxidant enzymes in cholesterol fed rabbits.

In this study we examined the antioxidant effect of curcumin on lipid oxidation in vitro and in vivo. In vitro, curcumin at 5 microgM concentration completely prevented low-density lipoprotein (LDL) oxidation by CuS0(4), indicating that curcumin is an effective antioxidant in vitro. In vivo, feeding a pure cholesterol (PC)-rich diet to rabbits significantly increased the plasma and liver lipids as well as thiobarbituric acid reactive substances (TBARS) levels.

Intracellular free calcium content plays a role in low magnesium-induced increases in prostacyclin production.

In a previous study, we found that magnesium deficiency stimulated prostacyclin production and suggested that this stimulation resulted from an enhanced Ca2+ influx induced by magnesium deficiency. In this study, we further examined prostacyclin generation in cultured human umbilical vein endothelial cells after intracellular free calcium content ([Ca2+]i) was altered by addition of diltiazem, nifedipine, verapamil, sodium cyanide (NaCN), ruthenium red or quinidine to a low magnesium medium. The results showed that diltiazem, nifedipine, verapamil and ruthenium red inhibited 45Ca2+ influx, and NaCN and quinidine had no effect on 45Ca2+ influx.

Vitamin B6 compounds are capable of reducing the superoxide radical and lipid peroxide levels induced by H2O2 in vascular endothelial cells in culture.

Pyridoxamine, pyridoxine, and pyridoxal phosphate were tested to examine if they have antioxidant properties. Endothelial cells exposed to 0.5 mM H(2)O(2) for 2 hours increased the superoxide anion and lipid peroxide levels as biomarkers of oxidative stress.

Curcumin prevents the oxidation and lipid modification of LDL and its inhibition of prostacyclin generation by endothelial cells in culture.

Low-density lipoprotein (LDL) was isolated from human plasma and oxidized by 5microM copper sulfate for 4h at 37 degrees C in the absence and presence of 1, 3, 5, 10, or 20microM of curcumin. LDL oxidized in the absence of curcumin (oxLDL) showed an increased levels of conjugated dienes, lipid peroxides (TBARS) and lysolecithin (lysoPC) and a significant loss of polyunsaturated fatty acids (PUFA). LDL oxidized with 5microM copper sulfate in the presence of curcumin caused a significant decrease of conjugated diene, lipid peroxides, lysoPC and significant increase of PUFA compared to oxLDL.

The negative effects of hydrogenated trans fats and what to do about them.

Partially hydrogenated vegetable oils have been in the American diet since 1900. More than 50 years ago they were found to contain trans fatty acids that were different from natural fatty acids in plant oils and in animal fat. There was growing evidence that the consumption of trans fats have negative health effects, including increasing plasma lipid levels.

High-dose lovastatin decreased basal prostacyclin production in cultured endothelial cells.

The effect of lovastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on prostacyclin production was studied in cultured human umbilical vein endothelial cells. The results indicated that lovastatin induced a significant dose- and time-dependent decrease of arachidonic acid release from the cells, an inhibition of phospholipase A(2) (PLA(2)) activity, a reduction of [(3)H]choline in lysophosphatidylcholine (lysoPC), and a diminishment of (45)Ca(2+) influx into the cells. The decreased arachidonic acid release was not reversed by addition of either intermediate products during cholesterol synthesis, such as mevalonate, geranylgeraniol, farnesol, or cholesterol and lipoprotein although a reduced concentration of cholesterol in the cells, caused by lovastatin, was reversed by added cholesterol.

Low magnesium stimulated prostacyclin generation in cultured human endothelial cells.

Prostacyclin, synthesized from arachidonic acid, is a strong vasodilator and the most powerful inhibitor known for platelet aggregation. Magnesium deficiency as a risk factor for cardiovascular diseases was related to imbalance of thromboxane and prostacyclin in the vasculature. In this study, we examined the effect of a low level of magnesium on prostacyclin generation in cultured human umbilical vein endothelial cells by measuring arachidonic acid release, 6-ketoprostaglandin F1alpha (6-keto-PGF1alpha) production, calcium ((45)Ca2+) influx, and activity of phospholipase A2 (PLA2) and cyclooxygenases (COX), which are the two main enzymes that control the synthesis of prostacyclin.

Trans fatty acids in partially hydrogenated soybean oil inhibit prostacyclin release by endothelial cells in presence of high level of linoleic acid.

Partially hydrogenated soybean oil (PHSBO) and natural soybean oil (SBO) were obtained from a commercial source and their fatty acids were fractionated into saturates, monoenes and diene fractions. The present study compared the effect of the total, monoene and diene fatty acid fractions of PHSBO with those of the SBO on the fatty acid composition of the cell phospholipids (PL) and the prostacyclin (PGI(2)) release by endothelial cells (EC) in culture. Results showed that arachidonic acid (AA) level decreased significantly and linoleic acid (LA) significantly increased in the cells incubated with the diene fraction or the monoene fraction of PHSBO plus 18:2 at 3:1 ratio compared to the cell incubated with those fractions of SBO.

Inhibition of prostacyclin release by cigarette smoke extract in endothelial cells is not related to enhanced superoxide generation and NADPH-oxidase activation.

Exposure of human umbilical endothelial cells (ECs) to cigarette smoke extract (CSE) activated the NADPH-oxidase enzyme and increased the production of superoxide (O-2) as well as reactive oxygen species (ROS). CSE also inhibited the prostacyclin (PGI2) formation by ECs. Preincubation of ECs with diphenylene iodonium (DPI), the inhibitor of NADPH oxidase, blocked the increase of O-2 production, but neither lowered the ROS level nor prevented the inhibition of PGI2 formation in CSE-treated cells.

27-Hydroxycholesterol causes remodeling in endothelial cell membrane lipid composition comparable to remodeling in the failed vein grafts of CABG patients.

Our objective is to determine if vascular remodeling in CABG patients is related to oxysterols, therefore, we compared failed vein grafts from 18 patients, available after a second coronary artery bypass grafting (CABG), with human endothelial cells (ECs). The ECs were cultured in minimum essential medium (MEM) with or without 27-hydroxycholesterol (27OHC), one of the oxysterol products of oxidatively modified low density lipoproteins (ox-LDL), as an agent to alter molecular mechanisms in vascular cells. Significant changes in phospholipid composition, in fatty acid profile and in calcium concentration were found in the failed vein compared to the native saphenous vein from the same (CABG) patient.

Atorvastatin reduces the plasma lipids and oxidative stress but did not reverse the inhibition of prostacyclin generation by aortas in streptozotocin diabetic rats.

The effect of atorvastatin (Lipitor) on diabetes-induced changes in plasma lipids, oxidative stress and the ability of aortic tissues to generate prostacyclin was studied in streptozotocin diabetic rats. In diabetic rats, plasma total cholesterol, triglycerides and serum glucose significantly increased compared to nondiabetic rats. Atorvastatin administration to diabetic rats did not affect hyperglycemia but significantly reduced plasma total cholesterol and triglycerides compared to diabetic rats.

The levels of bilirubin may be related to an inflammatory condition in patients with coronary heart disease.

In agreement with previous reports, we found that the bilirubin level is significantly lower in the blood of patients with coronary heart disease (CHD) than in age and sex matched controls. However, we found that the level of bilirubin in the blood seemed to be an age-dependent phenomenon and closely related to the activation of leukocytes. In 1,000 cardiac catheterized patients from Urbana.

27-Hydroxycholesterol inhibits neutral sphingomyelinase in cultured human endothelial cells.

To study the effect of 27-hydroxycholesterol (27OHC) on the catabolism of sphingomyelin, we cultured endothelial cells (ECs) from human umbilical veins with 27OHC, then measured activities of acid sphingomyelinase (ASMase) and neutral sphingomyelinase (NSMase) and sphingomyelin consumption by using [14C]sphingomyelin, and determined NSMase mRNA expressions by RT-PCR method. The results indicated that [14C]sphingomyelin accumulated in cells treated with 27OHC, and that the activities of both NSMase and ASMase were inhibited in ECs cultured with 27OHC. To further study the effect of 27OHC on NSMase, we used desipramine, an inhibitor of ASMase, to exclude the possible interference of ASMase's residual activity at neutral condition.

Vitamin C or Vitamin B6 supplementation prevent the oxidative stress and decrease of prostacyclin generation in homocysteinemic rats.

We hypothesize that homocysteinemia causes oxidative stress, decreases the aortic ability to generate prostacyclin and that antioxidants have a protective role. Four groups of eight rats each were fed for 8 weeks the control diet (group A), control diet with folic acid omitted and excess methionine (Me) added to drinking water (group B), diet B + 500 mg/kg of Vitamin C (group C) or diet B + 60 mg/kg Vitamin B6 (group D). The three groups of rats fed folic acid deficient (FD) diets (groups B, C and D) were homocysteinemic as indicated by the significant increase in their serum homocysteine (HC) concentration.

Trans fatty acids in hydrogenated fat inhibited the synthesis of the polyunsaturated fatty acids in the phospholipid of arterial cells.

Our hypothesis that the trans fatty acids in hydrogenated fat inhibited the synthesis of polyunsaturated fatty acids in the phospholipid of arterial cells was tested with five groups each with six pregnant porcine fed from d 35 of gestation and during lactation. The basal diet contained 2% corn oil (control). The other four diets included the control + 10% butter or 10% hydrogenated fat plus two levels of Mg.

High density lipoprotein can modulate the inhibitory effect of oxLDL on prostacyclin generation by rat aorta in vitro.

To examine the effect of oxidized low density lipoprotein (oxLDL) on prostacyclin (PGI2) generation by rat aorta in vitro and whether high density lipoprotein (HDL) has any protective effect against the inhibition of PGI2 generation induced by oxLDL is the objective of this study. Preincubation of aortas with oxLDL resulted in significant inhibition of PGI2 generation compared to preincubation with normal low density lipoprotein (nLDL) or buffer only. The inhibitory effect of oxLDL resided in its lipid moiety while the lipid fraction of nLDL showed no effect.

Changes in the phospholipid composition of the arterial cell can result in severe atherosclerotic lesions.

The oxysterol concentration in the plasma and the phospholipid composition of vascular tissue obtained by coronary artery bypass grafting (CABG) were compared with plasma and vascular tissue from age and sex matched controls. The plasma from CABG patients had a higher concentration of oxysterols than was present in the controls. Human endothelial cells were cultured for 72 hours in a medium containing plasma obtained from CABG patients, from controls or from the same controls to which 5 oxysterols were added to make the total oxysterol level equivalent to that in the CABG plasma and then pulsed with calcium (45Ca(2+)) for one hr.

Effect of low magnesium concentration and cholestane-3beta, 5alpha, 6beta-triol on levels of LDL receptor in cultured fibroblasts.

We investigated the level of low density lipoprotein receptors (LDLR) in fibroblasts upon treatment with low magnesium and/or cholestane-3beta, 5alpha, 6beta-triol (TriolC). After 72 h of incubation with low magnesium at a level of 188 micromol or lower, the LDLR levels, determined with immunoblotting analysis, were significantly reduced in the cultured cells. TriolC at a level of 1 microg/ml or higher also decreased LDLR level.

Antioxidative effects of lovastatin in cultured human endothelial cells.

The effects of lovastatin on glutathione peroxidase activity, hydrogen peroxide consumption, [3H]cholesterol uptake and [14C]acetate incorporation were investigated in cultured human endothelial cells. Treatment of endothelial cells with lovastatin in a medium without serum for 4 hr significantly increased both glutathione peroxidase activity and hydrogen peroxide consumption. This treatment also significantly inhibited cholesterol synthesis and cholesterol esterification.

Oxidized low density lipoprotein inhibits prostacyclin generation by rat aorta in vitro: a key role of lysolecithin.

The objective of this study was to examine the effect of oxLDL on prostacyclin (PGI2) generation by rat aortic segments and to see whether the lipid fraction of oxLDL or its components are responsible for that effect. We also tested if antioxidants have any protective role. LDL oxidized by copper was characterized by higher TBARS, conjugated diene, lysophosphatidylcholine (lyso PC), oxysterols and less polyunsaturated fatty acids (PUFA) than nLDL.

The levels of bilirubin may be related to an inflammatory condition in patients with coronary heart disease.

In agreement with previous reports, we found that the bilirubin level is significantly lower in the blood of patients with coronary heart disease (CHD) than in age and sex matched controls. However, we found that the level of bilirubin in the blood seemed to be an age-dependent phenomenon and closely related to the activation of leukocytes. In 1,000 cardiac catheterised patients from Urbana, USA suffering from CHD, the level of blood bilirubin was found to be lower than in age and sex-matched controls.