Background Endothelial function is impaired in coronary artery disease and may contribute to its clinical manifestations. Increased oxidative stress has been linked to impaired endothelial function in atherosclerosis and may play a role in the pathogenesis of cardiovascular events. This study was designed to determine whether endothelial dysfunction and vascular oxidative stress have prognostic impact on cardiovascular event rates in patients with coronary artery disease. Methods and Results Endothelium-dependent and -independent vasodilation was determined in 281 patients with documented coronary artery disease by measuring forearm blood flow responses to acetylcholine and sodium nitroprusside using venous occlusion plethysmography. The effect of the coadministration of vitamin C (24 mg/min) was assessed in a subgroup of 179 patients. Cardiovascular events, including death from cardiovascular causes, myocardial infarction, ischemic stroke, coronary angioplasty, and coronary or peripheral bypass operation, were studied during a mean follow-up period of 4.5 years. Patients experiencing cardiovascular events (n=91) had lower vasodilator responses to acetylcholine ( P <0.001) and sodium nitroprusside ( P <0.05), but greater benefit from vitamin C ( P <0.01). The Cox proportional regression analysis for conventional risk factors demonstrated that blunted acetylcholine-induced vasodilation ( P =0.001), the effect of vitamin C ( P =0.001), and age ( P =0.016) remained independent predictors of cardiovascular events. Conclusions Endothelial dysfunction and increased vascular oxidative stress predict the risk of cardiovascular events in patients with coronary artery disease. These data support the concept that oxidative stress may contribute not only to endothelial dysfunction but also to coronary artery disease activity.

Incubation of endothelial cells in vitro with high concentrations of glucose activates protein kinase C (PKC) and increases nitric oxide synthase (NOS III) gene expression as well as superoxide production. The underlying mechanisms remain unknown. To address this issue in an in vivo model, diabetes was induced with streptozotocin in rats. Streptozotocin treatment led to endothelial dysfunction and increased vascular superoxide production, as assessed by lucigenin-and coelenterazine-derived chemiluminescence. The bioavailability of vascular nitric oxide (as measured by electron spin resonance) was reduced in diabetic aortas, although expression of endothelial NOS III (mRNA and protein) was markedly increased. NOS inhibition with N G-nitro-L-arginine increased superoxide levels in control vessels but reduced them in diabetic vessels, identifying NOS as a superoxide source. Similarly, we found an activation of the NADPH oxidase and a 7-fold increase in gp91 phox mRNA in diabetic vessels. In vitro PKC inhibition with chelerythrine reduced vascular superoxide in diabetic vessels, whereas it had no effect on superoxide levels in normal vessels. In vivo PKC inhibition with N-benzoyl-staurosporine did not affect glucose levels in diabetic rats but prevented NOS III gene upregulation and NOS-mediated superoxide production, thereby restoring vascular nitric oxide bioavailability and endothelial function. The reduction of superoxide in vitro by chelerythrine and the normalization of NOS III gene expression and reduction of superoxide in vivo by N-benzoyl-staurosporine point to a decisive role of PKC in mediating these phenomena and suggest a therapeutic potential of PKC inhibitors in the prevention or treatment of vascular complications of diabetes mellitus. The full text of this article is available at http://www.circresaha.org. (Circ Res. 2001; 88:e14-e22.) Key Words: diabetes nitric oxide synthase protein kinase C uncoupling NADPH oxidase M yocardial infarction and stroke constitute major causes of death in patients with diabetes mellitus. Long-term diabetes is associated with macroangiopathy and microangi-opathy. Several hypotheses have been put forth to explain the adverse effects of hyperglycemia on the vasculature. These include the activation of the polyol pathway, nonenzymatic glycation, redox potential alterations, and stimulation of the diacylglycerol (DAG)-protein kinase C (PKC) pathway (for review, see Ishii et al 1). Although studies on the polyol pathway and nonenzymatic glycation remain inconclusive so far, more recent studies strongly point to a decisive role of the DAG-PKC pathway for the vascular complications associated with diabetes.

Pϭ0.008) were all independent predictors of the patient's 6-month outcome. Conclusions-In patients with ACS, MPO serum levels powerfully predict an increased risk for subsequent cardiovascular events and extend the prognostic information gained from traditional biochemical markers. Given its proinflammatory properties, MPO may serve as both a marker and mediator of vascular inflammation and further points toward the significance of PMN activation in the pathophysiology

Abstract-Angiotensin II infusion causes endothelial dysfunction by increasing NAD(P)H oxidase-mediated vascular superoxide production. However, it remains to be elucidated how in vivo angiotensin II treatment may alter the expression of the gp91 phox isoforms and the endothelial nitric oxide synthase (NOS III) and subsequent signaling events and whether, in addition to the NAD(P)H oxidase, NOS III contributes to vascular superoxide formation. We therefore studied the influence of in vivo angiotensin II treatment (7 days) in rats on endothelial function and on the expression of the NAD(P)H oxidase subunits p22 phox , nox1, nox4, and gp91 phox and NOS III. Further analysis included the expression of NO-downstream targets, the soluble guanylyl cyclase (sGC), the cGMP-dependent protein kinase I (cGK-I), and the expression and phosphorylation of the vasodilator-stimulated phosphoprotein (VASP) at Ser239 (P-VASP). Angiotensin II caused endothelial dysfunction and increased vascular superoxide. Likewise, we found an increase in vascular protein kinase C (PKC) activity, in the expression of nox1 (6-to 7-fold), gp91 phox (3-fold), p22 phox (3-fold), NOS III mRNA, and protein. NOS-inhibition with N G -nitro-L-arginine decreased superoxide in vessels from angiotensin II-treated animals, compatible with NOS-uncoupling. Vascular NO assessed with electron paramagnetic resonance was markedly reduced. Likewise, a decrease in sGC-expression and P-VASP levels was found. In vivo PKC-inhibition with chelerythrine reduced angiotensin II-induced superoxide production and markedly inhibited upregulation of NAD(P)H oxidase subunits. We therefore conclude that angiotensin II-induced increases in the activity and the expression of NAD(P)H oxidase are at least in part PKC-dependent. NADPH oxidase-induced superoxide production may trigger NOS III uncoupling, leading to impaired NO/cGMP signaling and to endothelial dysfunction in this animal model. The full text of this article is available at http://www.circresaha.org. (Circ Res. 2002;90:e58-e65.) Key Words: angiotensin II Ⅲ nitric oxide synthase uncoupling Ⅲ nox expression Ⅲ cGMP-dependent protein kinase Ⅲ vasodilator-stimulated phosphoprotein

Bedside tests for cardiac-specific troponins are highly sensitive for the early detection of myocardial-cell injury in acute coronary syndromes. Negative test results are associated with low risk and allow rapid and safe discharge of patients with an episode of acute chest pain from the emergency room.

Background-Angiotensin II activates NAD(P)H-dependent oxidases via AT 1 -receptor stimulation, the most important vascular source of superoxide (O 2 ⅐ Ϫ ). The AT 1 receptor is upregulated in vitro by low-density lipoprotein. The present study was designed to test whether hypercholesterolemia is associated with increased NAD(P)H-dependent vascular O 2 ⅐ Ϫ production and whether AT 1 -receptor blockade may inhibit this oxidase and in parallel improve endothelial dysfunction. Methods and Results-Vascular responses were determined by isometric tension studies, and relative rates of vascular O 2 ⅐

AimsThe aim of this study was to describe the characteristics of patients with atrial fibrillation (AF) enrolled in the Central Registry of the German Competence NETwork on Atrial Fibrillation (AFNET) and to assess current medical practice in patients treated at various levels of medical care in Germany.Methods and resultsFrom February 2004 to March 2006, 9582 ambulatory and hospitalized patients with ECG-documented AF were enrolled by 194 participating study centres from all levels of medical care in Germany. Clinical type of AF was reported as paroxysmal in 2893, persistent in 1873, and permanent in 3134 patients or classified as a first episode in 1035 patients. Predisposing conditions were common and present in 87.6% of the patients. Most patients were symptomatic with AF (75.1%). Rhythm control in persistent AF was provided to 53.4% of the symptomatic patients and to 47.8% of the patients without symptoms. Anticoagulation for stroke prevention was given to 71.4% of the patients considered eligible by applicable guidelines and to 48.4% of patients with low risk where guidelines do not recommend anticoagulation.ConclusionThis registry provides insight into current medical care of patients with AF in Germany. The use of oral anticoagulation in eligible patients was among the highest reported, whereas decisions on rate and rhythm control often do not follow current recommendations.

Recruitment and activation of polymorphonuclear neutrophils (PMNs) reflects a primary immunological response to invading pathogens and has also emerged as a hallmark of vascular inflammation. One of the principal enzymes released upon PMN activation is myeloperoxidase (MPO), a heme protein that not only generates cytotoxic oxidants but also impacts deleteriously on nitric oxide-dependent signaling cascades within the vasculature. Because MPO also associates with the membrane of PMN, we evaluated whether MPO could also function as an autocrine modulator of PMN activation. The extent of PMN membrane-associated MPO was elevated in patients with acute inflammatory vascular disease compared with healthy individuals. Isolated PMNs bound free MPO by a CD11b͞CD18 integrin-dependent mechanism. PMNs exposed to MPO were characterized by increased tyrosine phosphorylation and p38 mitogen-activated protein kinase activation. Also, nuclear translocation of NF B in PMN was enhanced after incubation with MPO, as was surface expression of CD11b. Binding of PMN to MPO-coated fibronectin surfaces amplified PMN degranulation, as evidenced by increased release of MPO and elastase. MPO also augmented PMN-dependent superoxide (O 2 •؊ ) production, which was prevented by anti-CD11b antibodies, but not MPO inhibitors. Collectively, these results reveal that binding of MPO to CD11b͞CD18 integrins stimulates PMN signaling pathways to induce PMN activation in a mechanism independent of MPO catalytic activity. These cytokine-like properties of MPO thus represent an additional dimension of the proinflammatory actions of MPO in vascular disease.atherosclerosis ͉ cytokine ͉ endothelium ͉ leukocyte ͉ nitric oxide