Oxidized low density lipoproteins inhibit relaxations of porcine coronary arteries. Role of scavenger receptor and endothelium-derived nitric oxide

TNFα induces endothelial dysfunction in rheumatoid arthritis via LOX-1 and arginase 2: reversal by monoclonal TNFα antibodies

AIMS

Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting joints and blood vessels. Despite low levels of low-density lipoprotein cholesterol (LDL-C), RA patients exhibit endothelial dysfunction and are at increased risk of death from cardiovascular complications, but the molecular mechanism of action is unknown. We aimed in the present study to identify the molecular mechanism of endothelial dysfunction in a mouse model of RA and in patients with RA.

METHODS AND RESULTS

Endothelium-dependent relaxations to acetylcholine were reduced in aortae of two tumour necrosis factor alpha (TNFα) transgenic mouse lines with either mild (Tg3647) or severe (Tg197) forms of RA in a time- and severity-dependent fashion as assessed by organ chamber myograph. In Tg197, TNFα plasma levels were associated with severe endothelial dysfunction. LOX-1 receptor was markedly up-regulated leading to increased vascular oxLDL uptake and NFκB-mediated enhanced Arg2 expression via direct binding to its promoter resulting in reduced NO bioavailability and vascular cGMP levels as shown by ELISA and chromatin immunoprecipitation. Anti-TNFα treatment with infliximab normalized endothelial function together with LOX-1 and Arg2 serum levels in mice. In RA patients, soluble LOX-1 serum levels were also markedly increased and closely related to serum levels of C-reactive protein. Similarly, ARG2 serum levels were increased. Similarly, anti-TNFα treatment restored LOX-1 and ARG2 serum levels in RA patients.

CONCLUSIONS

Increased TNFα levels not only contribute to RA, but also to endothelial dysfunction by increasing vascular oxLDL content and activation of the LOX-1/NFκB/Arg2 pathway leading to reduced NO bioavailability and decreased cGMP levels. Anti-TNFα treatment improved both articular symptoms and endothelial function by reducing LOX-1, vascular oxLDL, and Arg2 levels.

Characteristics of Blood Metabolic Profile in Coronary Heart Disease, Dilated Cardiomyopathy and Valvular Heart Disease Induced Heart Failure

Purpose: Metabolic impairment is one key contributor to heart failure (HF) pathogenesis and progression. The major causes of HF, coronary heart disease (CHD), dilated cardiomyopathy (DCM), and valvular heart disease (VHD) remains poorly characterized in patients with HF from the view of metabolic profile. We sought to determine metabolic differences in CHD-, VHD-, and DCM-induced HF patients and identify significantly altered metabolites and their correlations.

Procedure: In this study, a total of 96 HF cases and 97 controls were enrolled. The contents of 23 amino acids and 26 carnitines in fasting plasma were measured by a targeted liquid chromatography and mass spectrometry (LC-MS) approach.

Results: Nine metabolites (Histidine, Arginine, Citrulline, Glutamine, Valine, hydroxyhexadecenyl-carnitine, acylcarnitine C22, hydroxytetradecanoyl-carnitine, and carnitine) were found to be related with the occurrence of HF. Arginine, Glutamine and hydroxytetradecanoyl-carnitine could effectively distinguish CHD and DCM patients, and hydroxytetradecanoyl-carnitine and aspartic acid were able to classify CHD and VHD cohorts.

Conclusion: This study indicated that circulating amino acids and long-chain acylcarnitine levels were closely associated with progression of heart failure. Monitoring these metabolic alterations by LC-MS may help the differentiation of CHD, VHD, and DCM in the early stage, and provide new diagnostics targets or therapeutic interventions.

Pulmonary vascular dysfunction in metabolic syndrome

Metabolic syndrome is a critically important precursor to the onset of many diseases, such as cardiovascular disease, and cardiovascular disease is the leading cause of death worldwide. The primary risk factors of metabolic syndrome include hyperglycaemia, abdominal obesity, dyslipidaemia, and high blood pressure. It has been well documented that metabolic syndrome alters vascular endothelial and smooth muscle cell functions in the heart, brain, kidney and peripheral vessels. However, there is less information available regarding how metabolic syndrome can affect pulmonary vascular function and ultimately increase an individual's risk of developing various pulmonary vascular diseases, such as pulmonary hypertension. Here, we review in detail how metabolic syndrome affects pulmonary vascular function.

Phospholipase D2 loss results in increased blood pressure via inhibition of the endothelial nitric oxide synthase pathway

The Phospholipase D (PLD) superfamily is linked to neurological disease, cancer, and fertility, and a recent report correlated a potential loss-of-function PLD2 polymorphism with hypotension. Surprisingly, PLD2 -/- mice exhibit elevated blood pressure accompanied by associated changes in cardiac performance and molecular markers, but do not have findings consistent with the metabolic syndrome. Instead, expression of endothelial nitric oxide synthase (eNOS), which generates the potent vasodilator nitric oxide (NO), is decreased. An eNOS inhibitor phenocopied PLD2 loss and had no further effect on PLD2 -/- mice, confirming the functional relationship. Using a human endothelial cell line, PLD2 loss of function was shown to lower intracellular free cholesterol, causing upregulation of HMG Co-A reductase, the rate-limiting enzyme in cholesterol synthesis. HMG Co-A reductase negatively regulates eNOS, and the PLD2-deficiency phenotype of decreased eNOS expression and activity could be rescued by cholesterol supplementation and HMG Co-A reductase inhibition. Together, these findings identify a novel pathway through which the lipid signaling enzyme PLD2 regulates blood pressure, creating implications for on-going therapeutic development of PLD small molecule inhibitors. Finally, we show that the human PLD2 polymorphism does not trigger eNOS loss, but rather creates another effect, suggesting altered functioning for the allele.

Endothelium, lipoproteins and atherosclerotic vascular disease

The endothelium modulates vascular tone by releasing nitric oxide, which is a potent vasodilator and inhibitor of platelet aggregation. Together with prostacyclin, the endogenous nitrate nitric oxide has an important protective role in preventing vasospasm and thrombus formation. In addition, the endothelium is a source of contracting factors such as endothelin-1, thromboxane A2 and endoperoxides. Due to its strategic anatomical position, the endothelium is a primary target for injurious stimuli and cardiovascular risk factors. Low density lipoproteins reduce endothelium-dependent relaxation and enhance endothelium- dependent contraction. The same pattern of endothelial dysfunction occurs in hypercholesterolaemia and atherosclerosis. These alterations of endothelial function may contribute to vasospasm, ischaemia and thrombus formation, which are common events in patients with atherosclerotic vascular disease.

An Observational Study to Evaluate the Prevalence of Erectile Dysfunction (ED) and Prescribing Pattern of Drugs in Patients with ED Visiting an Andrology Specialty Clinic, Mumbai: 2012-14

INTRODUCTION

Erectile dysfunction (ED) is a common occurrence and its incidence is expected to increase significantly along with the increase in various lifestyle diseases. The drug utilization for ED is very low. Also, studies describing the prescription pattern in ED are lacking.

MATERIALS AND METHODS

We conducted a retrospective cross-sectional observational study, including a drug utilization analysis, of 606 prescriptions as per the standard guidelines (WHO and STROBE).

RESULTS

Out of 606, 249 (41%) were from the age group of 30-39 years. Addictions were present in 388 (64%). Out of 606, 186 had urological, 154 had cardiovascular and 102 had psychological co-morbid disorders. Out of 348, 201 were prescribed Tadalafil (low dose) on a once daily basis. Out of 172, 121 were prescribed Sildenafil (high dose) on an 'as and when required' basis. Nutritional/ herbal supplements were prescribed in 126/606. The ratio of 'Prescribed Daily Dose' to 'Defined Daily Dose' of Tadalafil, Sildenafil, and Dapoxetine were 1.1, 1.3 and 1.5 respectively.

CONCLUSION

Measures for de-addiction play an important role in the overall management of ED. The most common co-morbid disorders were urological, like BPH, LUTS, etc, followed by cardiovascular, psychological and diabetes. Overall, rational pharmacotherapy was observed. Tadalafil was the most commonly prescribed drug for ED. The main factor in the selection of a particular PDE5 inhibitor was its pharmacokinetics and cost. Udenafil, being the costliest, was the least prescribed. Dapoxetine was used in a significant number of individuals primarily for PE with ED. The combination of Papaverine, Chlorpromazine ± Alprostadil was used as intracavernosal injection in patients not responding to oral drugs.

Evaluation of the Associations between Vascular Endothelial Function and Coronary Artery Stenosis in Patients with Elevated Blood Pressure during Coronary Angiography

<p><b>Objectives:</b> The aim of the present study is to explore the correlation between vascular endothelial function and coronary artery stenosis in non-hypertensive patients with elevated blood pressure under stress.</p><p><b>Methods:</b> This study included 1141 patients suspected of having coronary artery disease (CAD) without hypertension. Coronary arteriography and ultrasonic detection were used to measure the flow-mediated dilatation (FMD) function in the brachial artery. Patients were divided into 2 groups according to coronary angiography: experiment group, patients with blood pressure ? 140/90 mm Hg; control group, patients with blood pressure <140/90 mm Hg. The correlation between vascular endothelial function and coronary artery stenosis was observed.</p><p><b>Results:</b> The majority of the patients in the control group were found to have either normal coronary arteries or stenosis <50%. Patients in the experiment group (those with invasive blood pressure [IBP] >140/90) were more likely to have some degree of coronary artery stenosis. Specifically, there were significantly more patients with >50% stenosis in the experiment when compared with the control group (<i>P</i> < .05). The FMD in the experiment group was significantly lower than that in the control group (<i>P</i> < .05).</p><p><b>Conclusion:</b> The non-hypertensive patients with elevated blood pressure under stress had coronary artery stenosis, which was associated with vascular endothelial dysfunction.</p>

Carbamylated low-density lipoprotein induces endothelial dysfunction

AIMS

Cardiovascular events remain the leading cause of death in Western world. Atherosclerosis is the most common underlying complication driven by low-density lipoproteins (LDL) disturbing vascular integrity. Carbamylation of lysine residues, occurring primarily in the presence of chronic kidney disease (CKD), may affect functional properties of lipoproteins; however, its effect on endothelial function is unknown.

METHODS AND RESULTS

Low-density lipoprotein from healthy donors was isolated and carbamylated. Vascular reactivity after treatment with native LDL (nLDL) or carbamylated LDL (cLDL) was examined in organ chambers for isometric tension recording using aortic rings of wild-type or lectin-like-oxidized LDL receptor-1 (LOX-1) transgenic mice. Reactive oxygen species (ROS) and nitric oxide (NO) production were determined using electron spin resonance spectroscopy. The effect of LDL-carbamyl-lysine levels on cardiovascular outcomes was determined in patients with CKD during a median follow-up of 4.7 years. Carbamylated LDL impaired endothelium-dependent relaxation to acetylcholine or calcium-ionophore A23187, but not endothelium-independent relaxation to sodium nitroprusside. In contrast, nLDL had no effect. Carbamylated LDL enhanced aortic ROS production by activating NADPH-oxidase. Carbamylated LDL stimulated endothelial NO synthase (eNOS) uncoupling at least partially by promoting S-glutathionylation of eNOS. Carbamylated LDL-induced endothelial dysfunction was enhanced in LOX-1 transgenic mice. In patients with CKD, LDL-carbamyl-lysine levels were significant predictors for cardiovascular events and all-cause mortality.

CONCLUSIONS

Carbamylation of LDL induces endothelial dysfunction via LOX-1 activation and increased ROS production leading to eNOS uncoupling. This indicates a novel mechanism in the pathogenesis of atherosclerotic disease which may be pathogenic and prognostic in patients with CKD and high plasma levels of cLDL.

Redox signaling in cardiovascular health and disease

Spatiotemporal regulation of the activity of a vast array of intracellular proteins and signaling pathways by reactive oxygen species (ROS) governs normal cardiovascular function. However, data from experimental and animal studies strongly support that dysregulated redox signaling, resulting from hyperactivation of various cellular oxidases or mitochondrial dysfunction, is integral to the pathogenesis and progression of cardiovascular disease (CVD). In this review, we address how redox signaling modulates the protein function, the various sources of increased oxidative stress in CVD, and the labyrinth of redox-sensitive molecular mechanisms involved in the development of atherosclerosis, hypertension, cardiac hypertrophy and heart failure, and ischemia-reperfusion injury. Advances in redox biology and pharmacology for inhibiting ROS production in specific cell types and subcellular organelles combined with the development of nanotechnology-based new in vivo imaging systems and targeted drug delivery mechanisms may enable fine-tuning of redox signaling for the treatment and prevention of CVD.

The recognition of biomaterials: pattern recognition of medical polymers and their adsorbed biomolecules

All biomedical materials are recognized as foreign entities by the host immune system despite the substantial range of different materials that have been developed by material scientists and engineers. Hydrophobic biomaterials, hydrogels, biomaterials with low protein binding surfaces, and those that readily adsorb a protein layer all seem to incite similar host responses in vivo that may differ in magnitude, but ultimately result in encapsulation by fibrotic tissue. The recognition of medical materials by the host is explained by the very intricate pattern recognition system made up of integrins, toll-like receptors, scavenger receptors, and other surface proteins that enable leukocytes to perceive almost any foreign body. In this review, we describe the various pattern recognition receptors and processes that occur on biomedical material surfaces that permit detection of a range of materials within the host.

Increased asymmetric dimethylarginine and enhanced inflammation are associated with impaired vascular reactivity in women with endometriosis

OBJECTIVE

Enhanced inflammatory responses which may inhibit vascular reactivity, are associated with endometriosis development. Asymmetric dimethylarginine (ADMA), an inhibitor of endogenous nitric oxide synthase, is also implicated in endothelial dysfunction. We aimed to determine whether plasma ADMA and systemic inflammation are associated with endothelial function in women with endometriosis.

METHODS

We evaluated 41 women with and 28 women without endometriosis. Plasma levels of lipids and inflammatory markers such as high sensitive-C reactive protein (hs-CRP), serum amyloid protein A (SAA), and interleukin-6 (IL-6) were measured in the two groups. We also measured levels of ADMA and symmetric dimethylarginine (SDMA). High-resolution ultrasonography measured flow-mediated vasodilation (FMD) to assess vasodilatory responses.

RESULTS

FMD was significantly lower in women with endometriosis compared to those without endometriosis (8.39 ± 0.43% vs 10.79 ± 0.54%, P = 0.001). While plasma lipid levels did not differ significantly between groups, levels of AMDA, but not SDMA, were significantly higher in women with endometriosis (409.7 ± 10.1 pmol/L vs 383.0 ± 48.3 pmol/L, P = 0.04). Inflammatory markers were also significantly higher in these women (hs-CRP: 1053.3 ± 252.0 ng/mL vs 272.0 ± 83.3 ng/mL, P = 0.02; SAA: 8.00 ± 1.53 μg/mL vs 3.82 ± 0.42 μg/mL, P = 0.04; IL-6: 2.73 ± 0.75 pg/mL vs 1.05 ± 0.60 pg/mL, P = 0.04). FMD was negatively correlated with plasma levels of ADMA (r = -0.37, P=0.01) and log hs-CRP (r = -0.34, P = 0.01).

CONCLUSION

Increased plasma ADMA levels and enhanced inflammation are associated with inhibited endothelial function in women with endometriosis.

Antihyperlipidemic and antioxidant effects of the mixture of ginseng radix and crataegi fructus: experimental study and preliminary clinical results

The mixture of Ginseng Radix and Crataegi Fructus (Gen-CF) was developed to increase the pharmacological effect of ginseng in the treatment of hypercholesterolemia and prevention of cardiovascular disease. This study evaluated the effects of Gen-CF on serum lipids of hypercholesterolemic rats in vivo, as well as its antioxidant activities in vitro, and explored its clinical effects on patients with hypercholesterolemia. In vitro, Gen-CF displayed 1,1-diphenyl-2-picrylhydrasyl and superoxide radical scavenging activities, and inhibited hemolysis induced by 2,2'-azobis-2-amidinopropane dihydrochloride in a dose-dependent manner. In vivo, Gen-CF significantly inhibited the increases of total cholesterol, low-density lipoprotein cholesterol and triglyceride in high cholesterol-diet and Triton WR-1339 models. It also significantly inhibited the decrease of high-density lipoprotein cholesterol in these models. In the clinical trial, Gen-CF significantly lowered total cholesterol, low-density lipoprotein cholesterol, triglyceride, total lipid and phospholipid, with no adverse events, including hepatic or renal toxicity. The data suggest that Gen-CF has the potential to treat hypercholesterolemia and prevent cardiovascular disease.

Oxidized low-density lipoprotein inhibits nitric oxide-mediated coronary arteriolar dilation by up-regulating endothelial arginase I

Oxidized low-density lipoprotein (OxLDL) causes impairment of endothelium-dependent, nitric oxide (NO)-mediated vasodilation involving l-arginine deficiency. However, the underlying mechanism remains elusive. Since arginase and endothelial NO synthase (eNOS) share the substrate l-arginine, we hypothesized that OxLDL may reduce l-arginine availability to eNOS for NO production, and thus vasodilation, by up-regulating arginase. To test this hypothesis, porcine subepicardial arterioles (70-130 μm) were isolated for vasomotor study and for immunohistochemical detection of arginase and eNOS expressions. The coronary arterioles dilated dose-dependently to the endothelium-dependent NO-mediated vasodilator serotonin. This vasodilation was inhibited in the same manner by NOS inhibitor N(G)-nitro-l-arginine methyl ester and by lumenal OxLDL (0.5 mg protein/mL). The inhibitory effect of OxLDL was reversed after treating the vessels with either l-arginine (3 mM) or arginase inhibitor difluoromethylornithine (DFMO; 0.4 mM). Consistent with vasomotor alterations, OxLDL inhibited serotonin-induced NO release from coronary arterioles and this inhibition was reversed by DFMO. Vascular arginase activity was significantly elevated by OxLDL. Immunohistochemical analysis indicated that OxLDL increased arginase I expression in the vascular wall without altering eNOS expression. Taken together, these results suggest that OxLDL up-regulates arginase I, which contributes to endothelial dysfunction by reducing l-arginine availability to eNOS for NO production and thus vasodilation.

Pistachio diet improves erectile function parameters and serum lipid profiles in patients with erectile dysfunction

We investigated the effects of Antep pistachio on International Index of Erectile Function (IIEF) scores, penile color Doppler ultrasound (PCDU) parameters and serum lipid levels in patients with ED. A total of 17 married male patients with ED for at least 12 months were included in this prospective study. Patients were put on a 100 g pistachio nuts diet for 3 weeks. IIEF and PCDU were evaluated before and after the pistachio diet. In addition, plasma total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglyceride were measured before and after dietary modifications from all subjects. Mean IIEF-15 score was 36 ± 7.5 before the diet and 54.2 ± 4.9 after the diet (P=0.001). Similarly, an increase in all five domains of IIEF was observed after the diet (P<0.05). Mean peak systolic velocity values before and after the pistachio diet were 35.5 ± 15.2 and 43.3 ± 12.4 cm s(-1), respectively (P=0.018). After the pistachio diet, TC and LDL levels decreased significantly, whereas HDL level increased (P=0.008, 0.007 and 0.001, respectively). We demonstrated that a pistachio diet improved IIEF scores and PCDU parameters without any associated side effects in patients with ED. Furthermore, the lipid parameters showed statistically significant improvements after this diet.

Prediction of diabetic retinopathy: role of oxidative stress and relevance of apoptotic biomarkers

Diabetic retinopathy (DR) is the foremost cause of blindness in working-aged worldwide; it is characterized by vascular and neuronal degeneration. Features of DR include leukocyte adhesion, increased vascular permeability, neovascularization and neuronal cell death. Early diagnosis and intervention are important to prevent or at least ameliorate the development of DR. Recent reports indicate that pathophysiological mechanisms leading to diabetic retinopathy include oxidative stress and retinal cell death cascades. Circulating biomarkers of oxidative stress such as malondialdehyde (MDA), thiobarbituric acid reacting substances (TBARS), conjugated diene (CD), advanced oxidation protein products (AOPP), protein carbonyl, 8-hydroxydeoxyguanosin (8-OHdG), nitrotyrosine, and F(2) isoprostanes and pro-apoptosis molecules (caspase-3, Fas, and Bax) are associated with increased susceptibility to develop DR in diabetic subjects. Thus, identification of oxidative stress and cell death biomarkers in diabetic patients could be in favor of predicting, diagnosis, and prevention of DR, and to target for novel therapeutic interventions.

Oxidative risk for atherothrombotic cardiovascular disease

In the vasculature, reactive oxidant species, including reactive oxygen, nitrogen, or halogenating species, and thiyl, tyrosyl, or protein radicals may oxidatively modify lipids and proteins with deleterious consequences for vascular function. These biologically active free radical and nonradical species may be produced by increased activation of oxidant-generating sources and/or decreased cellular antioxidant capacity. Once formed, these species may engage in reactions to yield more potent oxidants that promote transition of the homeostatic vascular phenotype to a pathobiological state that is permissive for atherothrombogenesis. This dysfunctional vasculature is characterized by lipid peroxidation and aberrant lipid deposition, inflammation, immune cell activation, platelet activation, thrombus formation, and disturbed hemodynamic flow. Each of these pathobiological states is associated with an increase in the vascular burden of free radical species-derived oxidation products and, thereby, implicates increased oxidant stress in the pathogenesis of atherothrombotic vascular disease.

Endothelial Function and Oxidative Stress

Increased oxidative stress impairs endothelial function and is thought to mediate vascular disease. Several pathological conditions increase the production of reactive oxygen species (ROS) in the vascular wall, including hypercholesterolemia, diabetes, and hypertension. These conditions are associated with endothelial dysfunction and cardiovascular disease. Thus, overall vascular function is dependent upon the balance of oxidant and antioxidant mechanisms, which determines endothelial function. Endothelial function is usually defined as nitric oxide (NO) production and/or bioavailability. Because ROS can interact and inactivate NO, vascular oxidative stress can lead to decrease NO bioavailability. This results in endothelial dysfunction and increased risk of cardiovascular diseases. Several pharmacological approaches have been used to improve endothelial function and decrease oxidative stress. These include treatment modalities that augment the antioxidant defense mechanisms, increase NO production, and inhibit ROS-generating enzymes. This review provides an overview of the relationship between endothelial function and oxidative stress.

A randomized placebo-controlled study on the effect of nifedipine on coronary endothelial function and plaque formation in patients with coronary artery disease: the ENCORE II study

AIMS

Endothelial dysfunction and plaque formation are features of atherosclerosis. Inhibition of L-type calcium channels or HMG-CoA pathway improves endothelial function and reduces plaque size. Thus, we investigated in stable coronary artery disease (CAD) the effects of a calcium antagonist on coronary endothelial function and plaque size.

METHODS AND RESULTS

In 454 patients undergoing PCI, acetylcholine (10(-6) to 10(-4) M) was infused in a coronary segment without significant CAD. Changes in coronary diameter were measured and an intravascular ultrasound examination (IVUS) was performed. On top of statin therapy, patients were randomized in a double-blind fashion to placebo or nifedipine GITS 30-60 mg/day and followed for 18-24 months. Blood pressure was lower on nifedipine than on placebo by 5.8/2.1 mmHg (P < 0.001) as was total and LDL cholesterol (4.8 mg/dL; P = 0.495), while HDL was higher (3.6 mg/dL; P = 0.026). In the most constricting segment, nifedipine reduced vasoconstriction to acetylcholine (14.0% vs. placebo 7.7%; P < 0.0088). The percentage change in plaque volume with nifedipine and placebo, respectively, was 1.0 and 1.9%, ns.

CONCLUSION

The ENCORE II trial demonstrates in a multi-centre setting that calcium channel blockade with nifedipine for up to 2 years improves coronary endothelial function on top of statin treatment, but did not show an effect of nifedipine on plaque volume.

Sexual dysfunction: the 'prima ballerina' of hypertension-related quality-of-life complications

Sexual dysfunction is currently considered a serious quality-of-life-related health problem, exerting a major impact on patients' and their sexual partners' life. Available data indicate that essential hypertension is a risk factor for sexual dysfunction, as male and female sexual dysfunction is more prevalent in hypertensive patients than normotensive individuals. Several mechanisms have been implicated in the pathogenesis of sexual dysfunction in hypertensive patients, and major determinants include severity and duration of hypertension, age, and antihypertensive therapy. Female sexual dysfunction, although more frequent than its male counterpart, remains largely under-recognized. Older antihypertensive drugs (diuretics, beta-blockers, centrally acting) exert negative results, whereas newer drugs have either neutral (calcium antagonists, angiotensin-converting enzyme inhibitors) or beneficial effects (angiotensin receptor blockers). Erectile dysfunction is related to ischemic heart disease and might be an 'early therapeutic window' of asymptomatic coronary artery disease. It seems of utmost importance for every physician treating hypertensive patients to become familiar with sexual dysfunction (through better education and specific seminars) for the proper management of these patients.

Changes in plasma lipids and increased low-density lipoprotein susceptibility to oxidation in pregnancies complicated by gestational diabetes: consequences of obesity

Dyslipidemia is associated with increased low-density lipoprotein (LDL) susceptibility to oxidation, a phenomenon associated with endothelial dysfunction, atherosclerosis, cell toxicity, and intrauterine growth retardation. The present study was designed to determine if women developing gestational diabetes mellitus (GDM) have both increased plasma lipids and LDL susceptibility to oxidation throughout pregnancy. We also wanted to study the effects of obesity upon these parameters. A nested case-control study was carried out in 45 women with uncomplicated pregnancies and 62 women diagnosed with GDM following the criteria of the American Diabetes Association. In all women, blood was drawn at 15, 24, and 32 weeks of gestation. Low-density lipoprotein oxidation was initiated by the addition of CuCl2, and formation of conjugated dienes was monitored. Glucose, cholesterol, triglycerides, vitamin E, estradiol, and progesterone were determined. In GDM, elevated levels of glucose, cholesterol, and triglycerides were observed when compared with the control group even in the first trimester, before the detection of diabetes. In the control group, the lag phase in the LDL oxidation was 85.3, 84.4, and 95.6 minutes at 15, 24, and 32 weeks of pregnancy, compared with 63.3, 63.4, and 74.5 minutes in the GDM group (P < .001 in the 3 periods). These differences remained when adjusted for the body mass index. In a multiple linear regression analysis, a negative correlation was observed between the lag phase and the body mass index (P < .001) and cholesterol (P < .001), whereas a positive one appeared with vitamin E (P < .05) and time of gestation (P < .001). In pregnancy, GDM increases LDL susceptibility to oxidation. Obesity and hypercholesterolemia further exacerbate this effect.

Acute myocardial infarction is associated with increased susceptibility of serum lipids to copper-induced peroxidation in vitro

BACKGROUND

Low-density lipoprotein (LDL) oxidation in the arterial intima plays a pivotal role in atherogenesis. Under physiologic conditions, several mechanisms protect LDL against oxidation, including hydrolysis of oxidation products by high-density lipoprotein (HDL)-associated enzymes. Some of these protective mechanisms are less effective under acute phase conditions.

HYPOTHESIS

Conditions of acute phase response, including acute myocardial infarction (MI), may be expected to result in increased susceptibility of serum lipids to oxidation. The present study was undertaken to test this possibility.

METHODS

Using our previously developed spectroscopic method, we have monitored prospectively the kinetics of copper-induced oxidation of serum lipids obtained from 15 men during and after acute MI. This was tested within 6 h from the onset of chest pain, on Days 1, 3, and 7 of infarction and 1 year after recovery.

RESULTS

The lag phase preceding oxidation of serum lipids was much shorter during the first week after MI when compared with values obtained after recovery (52-59 vs. 107 min, respectively, p <0.001). During the first week after MI, we observed no significant correlations between kinetic parameters and serum lipid composition, in contrast both to the correlations previously reported for hyperlipidemic patients and to the similar correlations observed in the present study after recovery.

CONCLUSIONS

Acute MI is associated with an increased susceptibility of serum lipids to oxidation in vitro. This propensity for oxidation may reflect enhanced in vivo formation of free radicals and/or reduced efficiency of defense mechanisms. Both these possibilities may carry detrimental effects on the course, complications, and prognosis of the patients after acute MI.

Redox-sensitive impairment of porcine coronary artery vasodilation by hypochlorite-modified LDL

Atherosclerotic vascular disease is associated with abnormal vasomotor function and oxidized low density lipoproteins (OxLDL) are believed to play a keyrole therein. Several compounds emerging from LDL lipid peroxidation have been shown to be able to alter vasomotion but the role of oxidized apoB in this process is not fully understood. Myeloperoxidase has been identified in atherosclerotic lesions and hypochlorite produced by this enzyme represents a strong oxidant. LDL oxidation by hypochlorite differs from most other forms of LDL oxidation in that hypochlorite-mediated oxidation shows a predilection for the protein moiety of LDL and does not result in lipid peroxidation. In this work, we use porcine coronary artery segments and show that hypochlorite-oxidized LDL (hyp-OxLDL) are able to impair dilatation induced by substance P in a dose- and modification-dependent way. Treatment of hyp-OxLDL with methionine resulted in quantitative elimination of reactive chloramines in LDL and complete recovery of relaxation. As application of the scavenger receptor antagonist maleylated albumin strongly interferes with the effects of hyp-OxLDL on vasomotion, we conclude that specific binding of hypochlorite-modified apoB is likely to be involved in mediating the observed effects.

Effects of statins beyond lipid lowering: Potential for clinical benefits

BACKGROUND

The role of statin drugs in the reduction of serum lipids has been well documented. More recently, evidence suggesting that statins may positively impact many organ systems and disease states independent of lipid reduction has emerged. The term "pleiotropic effects" has been used to refer to these properties. We reviewed the evidence exploring such potential effects.

METHODS

A search of the MEDLINE database was conducted for articles published between 1985 to 2005 on the pleiotropic and the lipid-lowering independent effects of statin drugs. The search terms "statin", "HMG-CoA reductase inhibitor", "pleiotropic effects", and "inflammation" were used. English language articles were selected for inclusion along with selected cross-references.

RESULTS

Numerous animal and clinical studies support the presence of a spectrum of beneficial effects for statins that are independent of their lipid-lowering properties. These effects are mediated by a variety of mechanisms and they suggest that the therapeutic role of statins may expand.

CONCLUSION

Statins have shown great promise beyond their lipid-lowering effects. Ongoing and future studies will help to further clarify the potential clinical impact of these "pleiotropic effects".

Absence of histamine-induced nitric oxide release in the human radial artery: implications for vasospasm of coronary artery bypass vessels

Radial artery (RA) bypass grafts can develop severe vasospasm. As histamine is known to induce vasospasm, its effect on RA was assessed compared with the classic bypass vessels internal mammary artery (MA) and saphenous vein (SV). The vessels were examined in organ chambers for isometric tension recording. Histamine induced contractions on baseline; the sensitivity was higher in RA and SV than MA. After precontraction with norepinephrine, histamine did not evoke relaxations of RA but induced relaxations of MA and less of SV at lower concentrations; it induced contractions at higher concentrations, reaching similar levels in all three vessels. Indomethacin did not affect the response of MA and RA but potentiated relaxations and reduced contractions of SV. Endothelium removal, Nω-nitro-l-arginine methyl ester (l-NAME), or the H2-receptor blocker cimetidine did not affect the response of RA, but inhibited relaxations and enhanced contractions in MA and inhibited relaxations in SV; in the latter, only l-NAME enhanced contractions. Real-time PCR detected much lower expression of endothelial H2-receptor in RA than MA or SV. Western blots revealed similar endothelial nitric oxide (NO) synthase expression in all three vessels. Relaxations to acetylcholine were identical in RA and MA. Thus histamine releases NO by activating the endothelial H2-receptor, the expression of which is much lower in RA than MA or SV. H2-receptor activation also releases prostaglandins in SV, partially antagonizing NO. The lack of histamine-induced NO production represents a possible mechanism of RA vasospasm.

The relationship between lipid profile and erectile dysfunction

The objective of this study is to investigate the relation between serum lipids (cholesterol, LDL, HDL, triglyceride (TG)) and erectile dysfunction (ED). The experimental methods involved comparison of 100 patients with organic ED (mean age of 43.59+/-10.51 y), with 100 healthy individuals (mean age of 43.72+/-9.76 y) regarding their lipid profile from January 2000 to June 2003 (cholesterol, TG, HDL, LDL). The results showed that there was a significant difference between mean plasma cholesterol and LDL levels in the individuals suffering from ED and the control group (P=0.04 and 0.02, respectively). The TG and HDL mean plasma level differences were not significant (P=0.583 and 0.299, respectively). Odds ratios for high plasma cholesterol level (>240 mg/dl) and high plasma LDL level (>160 mg/dl) were 1.74 and 1.97. The R2 was 0.04 for both cholesterol and LDL. Applying linear regression, the coefficient for cholesterol and LDL reduced the International Index of Erectile Function questionnaire scores by -0.036 and -0.035. In conclusion, this study, the correlation of cholesterol and LDL levels with ED strongly supports the role of hyperlipidemia treatment in both the prevention and management of ED.

Diabetes mellitus-associated atherosclerosis: mechanisms involved and potential for pharmacological invention

While diabetes mellitus is most often associated with hypertension, dyslipidemia, and obesity, these factors do not fully account for the increased burden of cardiovascular disease in patients with the disease. This strengthens the need for comprehensive studies investigating the underlying mechanisms mediating diabetic cardiovascular disease and, more specifically, diabetes-associated atherosclerosis. In addition to the recognized metabolic abnormalities associated with diabetes mellitus, upregulation of putative pathological pathways such as advanced glycation end products, the renin-angiotensin system, oxidative stress, and increased expression of growth factors and cytokines have been shown to play a causal role in atherosclerotic plaque formation and may explain the increased risk of macrovascular complications. This review discusses the methods used to assess the development of atherosclerosis in the clinic as well as addressing novel biomarkers of atherosclerosis, such as low-density lipoprotein receptor-1. Experimental models of diabetes-associated atherosclerosis are discussed, such as the streptozocin-induced diabetic apolipoprotein E knockout mouse. Results of major clinical trials with inhibitors of putative atherosclerotic pathways are presented. Other topics covered include the role of HMG-CoA reductase inhibitors and fibric acid derivatives with respect to their lipid-altering ability, as well as their emerging pleiotropic anti-atherogenic actions; the effect of inhibiting the renin-angiotensin system by either ACE inhibition or angiotensin II receptor antagonism; the effect of glycemic control and, in particular, the promising role of thiazolidinediones with respect to their direct anti-atherogenic actions; and newly emerging mediators of diabetes-associated atherosclerosis, such as advanced glycation end products, vascular endothelial growth factor and platelet-derived growth factor. Overall, this review aims to highlight the observation that various pathways, both independently and in concert, appear to contribute toward the pathology of diabetes-associated atherosclerosis. Furthermore, it reflects the need for combination therapy to combat this disease.

Low-density lipoprotein inhibits receptor-mediated prostaglandin synthesis without affecting calcium and arachidonic acid mobilization in human endothelial cells

Vascular serotonin 5-HT1 receptors have quiescent constrictor activity that is activated by other vasoactive agents such as histamine. Previously, we observed that the 5-HT1-selective agonist 5-carboxamidotryptamine (5-CT) potentiated histamine-stimulated arachidonic acid (AA) mobilization and prostaglandin production in human aortic endothelial cells (HAEC). In the present study, 5-CT was found to potentiate histamine-stimulated calcium mobilization but had no effect on intracellular calcium when added alone. Treatment of HAEC with human low-density lipoprotein (LDL) for 20 hours inhibited the histamine- plus 5-CT-stimulated production of prostaglandin F2alpha (PGF2alpha) and the prostacyclin metabolite 6-keto-PGF1alpha. However, the effects of histamine and histamine potentiation by 5-CT on intracellular Ca mobilization and AA release were resistant to LDL treatment. Conversely, the subsequent receptor-independent conversion of AA to prostaglandins was inhibited by LDL. These results demonstrate that histamine and serotonin receptor activity, measured as the stimulation of Ca and AA mobilization, is resistant to LDL exposure under mild oxidizing conditions, whereas the receptor-independent synthesis of prostaglandins is inhibited by LDL. The results also suggest that the LDL-stimulated mobilization of cellular AA is responsible for the LDL-mediated inhibition of prostaglandin synthesis. These findings suggest a mechanism by which LDL and/or atherosclerosis could promote the vascular liberation of AA that is not converted to endothelium-derived prostaglandins and is therefore available as substrate for the production of other eicosanoids.

Small low-density lipoprotein particles and endothelium-dependent vasodilation in postmenopausal women

Low concentrations of estrogen may decrease endothelial function in postmenopausal women. Elevated plasma triglycerides after menopause are frequently associated with a small, dense low-density lipoprotein (LDL) phenotype. Small LDL particles that are more susceptible to oxidation can also inhibit endothelium-dependent vasodilation. The purpose of the present study was to investigate whether hypertriglyceridemia-induced small LDL particles are associated with endothelial dysfunction in postmenopausal women. We studied 15 premenopausal and 41 postmenopausal women. Postmenopausal subjects were divided into those with LDL subclass pattern A (large particles) and those with pattern B (small particles). Plasma lipids, hormones, and diameter and oxidative susceptibility of LDL were measured. Vasodilatory responses of the brachial artery were evaluated by measuring flow-mediated vasodilation (FMD) and nitroglycerin-induced vasodilation (NID). FMD in both postmenopausal groups was significantly lower than in premenopausal women. FMD in subjects with pattern B was significantly smaller than in those with pattern A (4.9 +/- 1.9% versus 8.8 +/- 3.6%). NID did not differ significantly among the groups. Plasma triglyceride concentrations were higher, lag time for LDL oxidation was shortened, and LDL-derived thiobarbituric acid-reactive substance (TBARS) concentrations were significantly greater in subjects with pattern B than in premenopausal or pattern A subjects. LDL diameter correlated negatively with plasma triglycerides (r = -0.51) or LDL-derived TBARS (r = -0.44) and positively with LDL-lag time (r = 0.66). FMD correlated negatively with LDL-derived TBARS (r = -0.36) and positively with LDL diameter (r = 0.44) or LDL-lag time (r = 0.43). Vascular endothelial dysfunction may be associated with elevated triglyceride-induced small LDL particles that have enhanced oxidative susceptibility in postmenopausal women.

Artichoke juice improves endothelial function in hyperlipemia

Artichoke extracts have been shown to produce various pharmacological effects, such as the inhibition of cholesterol biosynthesis and of LDL oxidation. Endothelial dysfunction represents the first stage of atherosclerotic disease; it is usually evaluated in humans by a noninvasive ultrasound method as brachial flow-mediated vasodilation (FMV) and by the determination of several humoral markers such as vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin. Aim of the study was to investigate the effects of dietary supplementation with artichoke juice on brachial FMV of hyperlipemics. We studied 18 moderately hyperlipemic patients (LDL cholesterol > 130 <200 mg/dl and/or triglycerides >150 <250 mg/dl) of both genders and 10 hyperlipemic patients, matched for age, sex and lipid parameters. All subjects were under isocaloric hypolipidic diet. A basal determination of serum lipids, soluble VCAM-1, ICAM-1, E-selectin and brachial FMV was performed. Thereafter patients were given 20 ml/die of frozen artichoke juice. The same parameters were repeated after 6 weeks. After artichoke treatment there was an increase of triglycerides (156 +/- 54 vs 165 +/- 76 mg/dL, p <0.05) and a reduction of total cholesterol (261 +/- 37 vs 244 +/- 38 mg/dL, p <0.05) and LDL cholesterol (174 +/- 31 vs 160 +/- 34 mg/dL, p <0.05). Controls showed a significant decrease in total and LDL cholesterol (respectively: 267 +/- 22 vs 249 +/- 20 mg/dL and 180 +/- 24 vs 164 +/- 23 mg/dL, both p <0.001). After artichoke there was a decrease in VCAM-1(1633 +/- 1293 vs 1139 +/- 883 ng/mL, p <0.05) and ICAM-1(477 +/- 123 vs 397 +/- 102 ng/mL, p <0.05), brachial FMV increased (3.3 +/- 2.7 vs 4.5 +/- 2.4%, p <0.01), while controls did not exhibit significant changes in VCAM-1, ICAM-1, E-selectin and brachial FMV. Univariate analysis showed that, in artichoke patients, changes of VCAM-1 and ICAM-1 were significantly related to changes in brachial FMV (respectively: r=-0.66 and r=-0.62; both p <0.05). In conclusion, artichoke dietary supplementation seems to positively modulate endothelial function in hypercholesterolemia.

Plasma level of oxidized low-density lipoprotein is an independent determinant of coronary macrovasomotor and microvasomotor responses induced by bradykinin

OBJECTIVES

We examined the relationship between coronary endothelium-dependent vasodilation in response to bradykinin (BK) and plasma levels of oxidized low-density lipoprotein (oxLDL) in subjects with normal coronary arteries.

BACKGROUND

It is unclear whether the plasma oxLDL level is a determinant of coronary endothelial function. Bradykinin plays an important role in regulating resting coronary tone and flow-mediated coronary vasomotion.

METHODS

Coronary blood flow (CBF) in the left anterior descending (LAD) coronary artery was assessed by quantitative angiography and a Doppler flow wire in 94 consecutive subjects with normal coronary arteries. The plasma oxLDL level was measured by enzyme-linked immunosorbent assay using DLH3R, a specific antibody against oxLDL.

RESULTS

Plasma levels of oxLDL in diabetic subjects (n = 13) were higher than those in non-diabetic subjects (n = 81). Plasma levels of oxLDL correlated with body mass index (BMI). Bradykinin at doses of 0.2, 0.6, and 2.0 microg/min caused dose-dependent increases in diameter and CBF in the LAD coronary artery. By a univariate analysis, oxLDL levels significantly correlated with epicardial (r = -0.30, p < 0.0001) and resistant (r = -0.36, p = 0.003) coronary vasodilator responses to BK at 2.0 microg/min, whereas total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides were not associated with these coronary responses. In a stepwise multivariate analysis, oxLDL levels were significantly correlated with epicardial and resistant coronary vasomotor responses to BK, independent of age, gender, smoking status, other lipid levels, BMI, hypertension, and diabetes.

CONCLUSIONS

The plasma level of oxLDL is an appropriate surrogate for assessing coronary endothelial-dependent vasomotor function as estimated by responses to BK compared with conventional risk factors for atherosclerosis.

Endothelial and Smooth Muscle Cell Dysfunction in Human Atherosclerotic Radial Artery

The radial artery (RA) is increasingly used as coronary artery bypass graft. In rare cases, however, it is macroscopically atherosclerotic at time of harvest. We examined how the regulation of vascular tone is altered under such circumstances. Macroscopically evident atherosclerotic lesions were observed in 3 of 429 RA (0.7%) isolated within 2 years. Histology revealed severe plaque formation; however, von Willebrand Factor staining showed a morphologically intact endothelium (n = 3). Endothelium-dependent relaxations to acetylcholine (10(-5) M) were reduced in atherosclerotic RA (32 +/- 6%; n = 3) as compared with control (78 +/- 4%; n = 10; P = 0.0001). Receptor-independent contractions to KCl (100 mM) were reduced in atherosclerotic RA (33.19 +/- 5.06 mN; n = 3) as compared with control (108.02 +/- 15.76 mN; n = 9; P < 0.05). Similarly, contractions to thrombin (1 U/ml) were reduced in atherosclerotic RA (3.02 +/- 1.58 mN; n = 3) as compared with control (10.97 +/- 5.12 mN; n = 8). Likewise, receptor-mediated contractions to norepinephrine were reduced in atherosclerotic RA (27.64 +/- 12.48 mN; n = 3) as compared with control (82.74 +/- 11.36 mN; n = 9; P < 0.05). Atherosclerosis is rare in RA of patients with coronary artery disease, but it does occur. Atherosclerotic RA exhibits a dysfunction of both endothelium and vascular smooth muscle. This dysfunction may favor thrombus formation and accelerated atherogenesis. Therefore, atherosclerotic RA should not be used for coronary artery bypass grafting.

The role of statins in vascular disease

BACKGROUND

Recent publications have highlighted the benefits of statins in non-cardiac occlusive disease but also the failure of vascular surgeons to recognise and treat the risk factors for atherosclerosis, in particular hypercholesterolaemia. The aim of this review is to clarify the current experimental and clinical evidence for the use of statins in vascular disease.

METHODS

Literature compiled from an extensive search of Medline and the Cochrane database has been used for the basis of this review.

RESULTS

Experimental and clinical evidence consistently reports that statins improve endothelial dysfunction, are anti-inflammatory, anti-proliferative, anti-thrombogenic and anti-proteolytic. These effects are known to inhibit atherogenesis and improve plaque stability. Independent groups support the use of statins in the prevention of both primary and secondary cardiac events. The National Stroke association recommends their use to reduce strokes following myocardial infarction and the Heart Protection Study reports benefits in patients with non-cardiac occlusive disease.

CONCLUSIONS

There is substantial evidence advocating the use of statins in patients with clinically significant vascular disease. In the future this may evolve to include those patients at risk from neointimal hyperplasia, aneurysmal disease and ischaemia reperfusion injury.

Rabbit aortic endothelial dysfunction by low-density lipoprotein is attenuated by L-arginine, L-ascorbate and pyridoxine

1. We investigated the relative effectiveness of L-arginine, L-ascorbate and pyridoxine in preventing the impairment of endothelium-mediated vasorelaxation induced by native low-density lipoprotein (nLDL) from healthy subjects, oxidised LDL (oxLDL, formed by oxidation of nLDL) or nLDL from type II diabetic patients (dLDL). 2. Rabbit aortic rings were exposed to nLDL, dLDL or oxLDL (50-200 mg protein l-1), or corresponding vehicle, following which they were constricted with noradrenaline 10(-6) M; concentration-relaxation curves were determined to acetylcholine (ACh), A23187, or sodium nitroprusside (NP), in the absence or presence of L-arginine (10(-5)-10(-3) M), L-ascorbate (10(-5)-10(-3) M) and pyridoxine (0.5-2.0 mM). 3. nLDL, dLDL and oxLDL all inhibited relaxant responses to ACh and A23187, but not to NP, in a concentration-dependent manner (oxLDL>dLDL>nLDL). 4. In the presence of all LDL preparations, L-arginine, L-ascorbate or pyridoxine each improved ACh and A23187 responses, although none completely normalised endothelium-dependent relaxations. The maximal effect of L-arginine occurred at 10(-4) M. The combination of L-arginine 10(-4) M, L-ascorbate 10(-5) M and pyridoxine 2.0 mM was equally effective as L-arginine 10(-4) M alone. 5. Our results confirm that nLDL, dLDL and oxLDL exert inhibitory effects on endothelium dependent, but not endothelium independent, relaxation of rabbit aorta. ACh and A23187 responses in the presence of any LDL species can be ameliorated by supplementation with L-arginine, L-ascorbate or pyridoxine, either singly or in combination, with no agent or combination proving superior to L-arginine alone. Nevertheless, ACh and A23187 responses are not completely normalised with such supplements, suggesting that there also exists a component of LDL-induced inhibition of endothelium-mediated vasorelaxation that is independent of the nitric oxide system.

Antiplatelet activity of semotiadil fumarate

Calcium antagonists are known to exert antiplatelet activity. Semotiadil fumarate (SD-3211), a new benzothiazine, was therefore examined for its antiplatelet activity. The inhibitory activity on adenosine diphosphate (ADP)-, collagen-, arachidonic acid (AA)-, and platelet activating factor (PAF)-induced platelet aggregation after the 1-, 30-, 60- and 120-min incubation at concentrations ranging from 1 x 10(-3), 1 x 10(-4), 1 x 10(-5), 1 x 10(-6) and 1 x 10(-7) was examined. The data were compared with those using diltiazem, nifedipine and amlodipine under identical conditions in blood from eight healthy volunteers (four males, four females; aged 23-36 years) and eight hypertensive patients (four males, four females; aged 31-46 years). Semotiadil showed a dose-dependent inhibition of platelet aggregation in vitro with all the agents examined. Using the various aggregation-inducing agents, the dose-dependent inhibitory action was comparable for all the compounds tested. The antiaggregatory potency was in the order diltiazem, semotiadil, amlodipine and nifedipine. The incubation period did not significantly affect the antiaggregatory effect. No difference between platelets derived from healthy volunteers and hypertensive patients was noted. These findings indicate potent antiplatelet activity of the new calcium antagonist semotiadil.

Detrimental vascular effects of lysophosphatidylcholine is limited by other phospholipid components of low-density lipoprotein

Current consensus suggests that lysophosphatidylcholine is the major detrimental factor in oxidized low-density lipoprotein that may contribute to the alterations of vasomotor responses associated with atherosclerosis. This study investigated the influences of lysophosphatidylcholine and major lipid components in oxidized low-density lipoprotein on vascular relaxation. We also determine if there was any interaction between these phospholipid components on relaxation. Porcine coronary artery rings were incubated with lysophosphatidylcholine, phosphatidylcholine or sphingomyelin. After contraction by the thromboxane A2 mimetic U46619, rings were relaxed with bradykinin and calcium ionophore A23187. Lysophosphatidylcholine with a higher proportion of stearoyl-lysophosphatidylcholine to palmitoyl-lysophosphatidylcholine ratio caused greater reduction of relaxational responses. While phosphatidylcholine and sphingomyelin had no effect on vascular relaxation, they reduced the ability of lysophosphatidylcholine to impair vascular relaxation. Our results thus suggested that the effectiveness of oxidized low-density lipoprotein at inhibiting vasodilatory responses may be determined by the relative proportion of different types of lysophosphatidylcholine as well as the amount of other phospholipid components: phosphatidylcholine and sphingomyelin.

The expanding scope of the metabolic syndrome and implications for the management of cardiovascular risk in type 2 diabetes with particular focus on the emerging role of the thiazolidinediones

Over the last decade, new factors including endothelial dysfunction, vascular inflammation, and abnormalities of blood coagulation have joined more established components of the metabolic syndrome, such as hyperglycemia, hypertension, dyslipidemia, and visceral obesity. Many of these factors are known to promote atherosclerosis and the clustering of metabolic abnormalities within the syndrome makes a major contribution to the increased risk of cardiovascular disease and death associated with type 2 diabetes. Given that most patients have multiple cardiovascular risk factors, good glycemic control does not, by itself, adequately reduce the burden of cardiovascular disease associated with diabetes and clinical management needs to address the full profile of cardiovascular risk. The thiazolidinediones have potentially beneficial effects on many components of the metabolic syndrome and so may help to improve cardiovascular outcomes in type 2 diabetes.

Oxidized low-density lipoprotein inhibits endothelium-dependent vasodilation by an antioxidant-sensitive, lysophosphatidylcholine-independent mechanism

Previous studies have shown that oxidized low-density lipoprotein (LDL) can impair endothelial function and that this can be overcome in vivo by administration of vitamin E. However, it is unclear whether this effect of oxidized LDL is due to lysophosphatidylcholine or other components of oxidized LDL, and it is also uncertain if the protective effect of vitamin E is related to its antioxidant action. The objectives of the current study were to define how much of the effect of extensively oxidized LDL on endothelium-dependent relaxation (EDR) was in fact due to lysophosphatidylcholine, to determine if the effect of oxidized LDL involved oxidant stress to the endothelium, and, if so, to ascertain if this could be blocked by oxyradical scavengers or antioxidants. Endothelial function was assessed by measuring vasodilation in preconstricted rat mesenteric artery rings in response to acetylcholine. In the presence of 100 microg/mL oxidized LDL, 25-fold higher concentrations of acetylcholine were required for the same degree of vasorelaxation. Similar concentrations of native LDL or acetyl LDL had no effect, but 100 microg/mL phospholipase A(2)-treated LDL or 20 microM lysophosphatidylcholine produced a similar inhibition of EDR. Removal of more than 90% of lysophosphatidylcholine from oxidized LDL did not affect its ability to inhibit EDR, nor did treatment of oxidized LDL with borohydride. This effect of oxidized LDL was blocked by preincubation of arterial rings with vitamin E, probucol, or BO-653 (a potent lipophilic antioxidant), but not by superoxide dismutase. In contrast, the inhibition of EDR by lysophosphatidylcholine was unaffected by antioxidants. Calphostin C prevented the inhibition of EDR by oxidized LDL and lysophosphatidylcholine. These studies demonstrate that at least part of the effect of oxidized LDL on EDR is independent of lysophosphatidylcholine, lipid peroxides, and superoxide release but appears to involve intracellular oxidative stress and protein kinase C activation.

Interactions of angiotensin II with NAD(P)H oxidase, oxidant stress and cardiovascular disease

An elevation in angiotensin II (Ang II) levels is a common occurrence in a diverse number of cardiovascular diseases including hypertension, hypercholesterolaemia, atherosclerotic coronary artery disease, left ventricular hypertrophy (LVH), heart failure and diabetes. An important effect of Ang II is activation of the NAD(P)H oxidase, a major source of reactive oxygen species (ROS) production by vascular cells. This increase in cellular ROS contributes to the pathogenesis of vascular disease by altering endothelial cell function, enhancing smooth muscle cell growth and proliferation, stimulating inflammatory proteins, including macrophage chemoattractant agents, growth factors and cytokines, and modulating matrix remodelling. Studies of genetically-altered mice have unequivocally shown that activation of the NAD(P)H oxidase by Ang II contributes to hypertension, LVH and atherosclerosis. Furthermore, increasing evidence suggest that the NAD(P)H oxidase contributes to human disease, suggesting that it is a potential target for future therapeutic intervention.

Vitamin C, diclophenac, and L-arginine protect endothelium-dependent vasodilation against elevated circulating fatty acid levels in humans

An acute elevation of circulating non-esterified fatty acids (NEFAs) has previously been shown to impair endothelium-dependent vasodilation (EDV). In this study, we investigated if local administration of vitamin C (n=8, 18 mg/min), L-arginine (n=8, 12.5 mg/min), or the cyclooxygenase (COX) inhibitor diclophenac (n=8, 0.5 mg/min) can counteract the endothelial dysfunction seen during infusion of Intralipid plus heparin (n=10). EDV and endothelium-independent vasodilation (EIDV) were studied in the forearm after local administration of methacholine chloride (Mch; 2 and 4 microg/min) and sodium nitroprusside (SNP; 5 and 10 microg/min). Forearm blood flow (FBF) was determined with venous occlusion plethysmography. Intralipid and heparin increased circulating NEFA levels sevenfold and impaired EDV (P<0.001 vs baseline). Concomitant administration of L-arginine or diclophenac abolished the NEFA-induced impairment in EDV. Concomitant vitamin C administration actually improved EDV (P<0.05 vs baseline). NEFA elevation increased EIDV (P<0.01), but this effect was not significant after L-arginine or diclophenac infusions. In conclusion, an acute elevation of circulating NEFAs led to impaired EDV. Administration of L-arginine, vitamin C or COX inhibition abolished this effect, suggesting that NEFAs might interact with endothelial vasodilatory function through multiple mechanisms.

Acute Chlamydia pneumoniae infection causes coronary endothelial dysfunction in pigs

BACKGROUND

Coronary endothelial dysfunction contributes to the pathogenesis of acute coronary syndromes (ACSs). Acute Chlamydia pneumoniae infection has been epidemiologically associated with ACS. In this study, we investigated whether acute C. pneumoniae infection could alter the endothelial vasomotor function of porcine coronary vessels.

METHODS AND RESULTS

Twenty pigs, 7-9 kg in weight, were inoculated intratracheally with C. pneumoniae (n=12) or saline (n=8), and investigated at 3 days (five infected/four non-infected) and 2 weeks (5+2 infected/four non-infected) after inoculation. The endothelium-dependent reactivity of coronary microcirculation was assessed at both time points by measuring peak coronary flow velocity (CFV) in response to bradykinin, before and after infusions with glutathione, an antioxidant, and L-arginine, a substrate for nitric oxide synthase (NOS). CFV after bradykinin was significantly decreased in infected animals at both time points. At 2 weeks, both glutathione and L-arginine significantly improved CFV after bradykinin. CFV after sodium nitroprusside (SNP) was similar in both groups. At 3 days, the relaxation responses of bradykinin-induced pre-contracted left anterior descending (LAD) coronary rings to bradykinin were significantly less in infected animals. N(G)-nitro-L-arginine-methyl-ester, an NOS inhibitor, had significantly greater inhibitory effect on bradykinin-induced relaxation in infected animals. Plasma nitrate-nitrite and fibrinogen, and NOS activity from LAD coronary samples were significantly increased in infected animals.

CONCLUSION

Acute C. pneumoniae infection causes endothelial dysfunction of both resistance and epicardial coronary vessels, and favours a pro-coagulant status. These effects could in part account for the epidemiologically suggested association between acute infection and ACS.

Effects of tadalafil on erectile dysfunction in men with diabetes

OBJECTIVE

To evaluate the efficacy and safety of tadalafil taken as needed before sexual activity by men with diabetes and erectile dysfunction (ED).

RESEARCH DESIGN AND METHODS

Men with type 1 or type 2 diabetes and a minimum 3-month history of ED were randomly allocated to one of three groups: placebo (n = 71), tadalafil 10 mg (n = 73), or tadalafil 20 mg (n = 72) taken up to once daily for 12 weeks. Changes from baseline in mean scores on the erectile function domain of the International Index of Erectile Function (IIEF) and changes from baseline in the proportion of "yes" responses to question 2, "Were you able to penetrate?," and 3, "Were you able to complete intercourse?," of the Sexual Encounter Profile were coprimary outcome measures.

RESULTS

A total of 191 (88%) of 216 patients completed the study. Treatment with tadalafil significantly improved all primary efficacy variables, regardless of baseline HbA(1c) level. Therapy with tadalafil also significantly improved a number of secondary outcome measures, including changes in other IIEF domains, individual IIEF questions, and percentage of positive responses to a global assessment question measuring erection improvement. Treatment with tadalafil did not alter mean HbA(1c) levels. Tadalafil was well tolerated, with headache and dyspepsia being the most frequent adverse events with active treatment.

CONCLUSIONS

Tadalafil therapy significantly enhanced erectile function and was well tolerated by men with diabetes and ED.

Chronic hydroxymethylglutaryl coenzyme a reductase inhibition and endothelial function of the normocholesterolemic rat: comparison with angiotensin-converting enzyme inhibition

Hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors seem to have clinical benefits beyond those predicted by their lipid-lowering action. The objective was to evaluate the vascular effect of long-term treatment with statins on isolated rat aorta and their ability to prevent the acute toxicity of oxidized low-density lipoproteins (oxLDLs) compared with angiotensin-converting enzyme (ACE) inhibitors. Four groups of Wistar rats were treated for 5 weeks. Group 1 received pravastatin 20 mg/kg/d orally; group 2 received atorvastatin 10 mg/kg/d; group 3 received ciprofibrate 25 mg/kg/d; and group 4 served as control. Total cholesterol and triglyceride plasma levels were not altered, except in group 3, in which both parameters were decreased. The inhibitory effect of the endothelium on serotonin-induced contractions was significantly increased in group 1. A significant leftward shift of the concentration-response curves to acetylcholine (1 nM-0.1 mM) was observed in group 1 but the maximal relaxation to acetylcholine was similar in the four groups. In contrast, in the presence of human Cu2+-oxLDL (300 microg/ml, 30 min of preincubation), the maximal relaxation to acetylcholine was markedly decreased (p < 0.02) in groups 3 and 4 versus that of groups 1 and 2. No difference in superoxide accumulation was observed by the chemiluminescence technique. Cyclic guanosine monophosphate (cGMP), measured by enzyme immunoassay in aortic tissues, was increased in group 1 in the presence of superoxide dismutase. Endothelial nitric oxide synthase (eNOS) expression was not altered (Western blot and enzyme-linked immunosorbent assay). In aortas isolated from a fifth group of rats treated with an ACE inhibitor (ramipril 10 mg/kg/d for 6 weeks), similar results to those of group 1 were observed except that the eNOS abundance was significantly enhanced. Thus, long-term statin treatment upregulates the eNOS pathway and attenuates the acute toxicity of human oxLDL. In contrast to chronic ACE inhibition, the eNOS abundance is not increased.

Effect of prolonged incubation with copper on endothelium-dependent relaxation in rat isolated aorta

1 We investigated the effects of prolonged exposure to copper (Cu(2+)) on vascular functioning of isolated rat aorta. 2 Aortic rings were exposed to CuSO(4) (3-24 h) in Dulbecco's modified Eagle medium with or without 10% foetal bovine serum (FBS) and then challenged with vasoconstrictors or vasodilators in the absence of Cu(2+). 3 Exposure to 2 micro M Cu(2+) in the absence of FBS did not modify the response to phenylephrine (PE) or acetylcholine (ACh) in aortic rings incubated for 24 h. Identical exposure in the presence of FBS increased the contractile response to 1 micro M PE by 30% (P<0.05) and impaired the relaxant response to 3 micro M ACh or 1 micro M A23187 (ACh, from 65.7+/-7.1 to 6.2+/-1.1%, n=8; A23187, from 74.6+/-8.2 to 12.0+/-0.8%, n=6; P<0.01 for both). Cu(2+) exposure did not affect the relaxant response to NO-donors. 4 Impairment of vasorelaxation appeared 3 h after incubation with 2 micro M Cu(2+) and required 12 h to attain a steady state. Vasorelaxation to ACh was partially restored by 1 mM tiron (intracellular scavenger of superoxide ions; maximum relaxation 34.2+/-6.4%, n=10, P<0.01 vs Cu(2+) alone), whereas catalase, superoxide dismutase or cycloheximide were ineffective. 5 Twenty-four hour-exposure to 2 micro M Cu(2+) did not affect endothelium integrity or eNOS expression, and increased the Cu content in arterial rings from 6.8+/-1.1 to 18.9+/-2.9 ng mg(-1) wet weight, n=8; P<0.01. 6 Our results show that, in the presence of FBS, prolonged exposure to submicromolar concentrations of Cu(2+) impaired endothelium-dependent vasorelaxation in aortic rings, probably through an intracellular generation of superoxide ions. British Journal of Pharmacology (2002) 136, 1185-1193