Angiotensin II stimulation of NAD(P)H oxidase activity: upstream mediators

Angiotensin II (Ang II)-stimulated hypertrophy of vascular smooth muscle cells is mediated by reactive oxygen species (ROS) derived from NAD(P)H oxidases. The upstream signaling mechanisms by which Ang II activates these oxidases are unclear but may include protein kinase C, tyrosine kinases, phosphatidylinositol-3-kinase, and Rac, a small molecular weight G protein. We found that Ang II-stimulated ROS production is biphasic. The first phase occurs rapidly (peak at 30 seconds) and is dependent on protein kinase C activation. The larger second phase of ROS generation (peak at 30 minutes) requires Rac activation, because inhibition of Rac by either Clostridium difficile toxin A or dominant-negative Rac significantly inhibits Ang II-induced ROS production. Phosphatidylinositol-3-kinase inhibitors (wortmannin or LY294002) and the epidermal growth factor (EGF) receptor kinase blocker AG1478 attenuate both Rac activation and ROS generation. The upstream activator of EGF receptor transactivation, c-Src, is also required for ROS generation, because PP1, an Src kinase inhibitor, abrogates the Ang II stimulation of both responses. These results suggest that c-Src, EGF receptor transactivation, phosphatidylinositol-3-kinase, and Rac play important roles in the sustained Ang II-mediated activation of vascular smooth muscle cell NAD(P)H oxidases and provide insight into the integrated signaling mechanisms whereby Ang II stimulation leads to activation of the growth-related NAD(P)H oxidases.     

Case Reports on Emergency Treatment of Cardiovascular Syndromes Through Heparin‐Mediated Low‐Density Lipoprotein/Fibrinogen Precipitation: A New Approach to Augment Cerebral and Myocardial Salvage

Abstract: We report the first experiences with HELP apheresis as an emergency treatment for acute cardiovascular syndromes; two patients who were not eligible for lysis therapy and catheter intervention were treated with HELP apheresis instead. Both patients had a most severe, generalized atherosclerosis and reached the hospital too late for conventional measures. In both cases, the use of the apheresis dramatically improved the clinical situation to such an extent that the possibilities of this apheresis system urge further investigation.     

Down-regulation of candidate tumor suppressor genes within chromosome band 13q14.3 is independent of the DNA methylation pattern in B-cell chronic lymphocytic leukemia

Loss of genomic material from chromosomal band 13q14.3 is the most common genetic imbalance in B-cell chronic lymphocytic leukemia (B-CLL) and mantle cell lymphoma, pointing to the involvement of this region in a tumor suppressor mechanism. From the minimally deleted region, 3 candidate genes have been isolated, RFP2, BCMS, and BCMSUN. DNA sequence analyses have failed to detect small mutations in any of these genes, suggesting a different pathomechanism, most likely haploinsufficiency. We, therefore, tested B-CLL patients for epigenetic aberrations by measuring expression of genes from 13q14.3 and methylation of their promotor region. RB1, CLLD7, KPNA3, CLLD6, and RFP2 were down-regulated in B-CLL patients as compared with B cells of healthy donors, with RFP2 showing the most pronounced loss of expression. To test whether this loss of gene expression is associated with methylation of CpG islands in the respective promotor regions, we performed methylation-sensitive quantitative polymerase chain reaction analyses and bisulfite sequencing on DNA from B-CLL patients. No difference in the methylation patterns could be detected in any CpG island of the minimally deleted region. Down-regulation of genes within chromosomal band 13q14.3 in B-CLL is in line with the concept of haploinsufficiency, but this tumor-specific phenomenon is not associated with DNA methylation.     

Acute simultaneous proximal occlusion of two major coronary arteries in acute myocardial infarction: successful treatment with percutaneous coronary intervention

Background: Acute myocardial infarction (AMI) due to acute simultaneous proximal occlusion of two major coronary arteries (ASOMC) is a rare but life‐threatening situation. Most patients die suddenly or go into cardiogenic shock (CS). In patients with AMI due to ASOMC identified by coronary angiography (CA), percutaneous coronary intervention (PCI) performed in both infarct‐related arteries (IRAs) at the same time as diagnostic CA is the fastest option to complete revascularization. However, no prospective studies regarding the outcome of such procedures have been published so far. Methods: In this prospective single‐center study, between October 2004 and March 2007, consecutive patients with acute coronary syndrome (ACS) reporting to our university hospital and regional referral center were evaluated for ASOMC by means of emergent CA. When diagnosed with ASOMC, PCI of the IRAs was performed. Clinical data were obtained at baseline, discharge, after 6 months, and after 1 year. Results: Out of 417 patients with ACS, 379 patients (90.9%) suffered an AMI. In 5 patients CA revealed an ASOMC. PCI was performed in 4 patients. One patient with severe triple‐vessel disease was referred for emergent coronary artery bypass graft (CABG) surgery after conventional PCI of one IRA. One patient died in‐hospital due to early in‐stent thrombosis after PCI. At 6‐month follow‐up and at 1‐year follow‐up, 4 patients were alive. Conclusion: In spite of the complex interventions, PCI patients had low in‐hospital mortality and good clinical results at 1‐year follow‐up. Our observations are important in the clinical decision‐making process of AMI due to ASOMC.     

Inducible nitric oxide synthase expression and cardiomyocyte dysfunction during sustained moderate ischemia in pigs

In acute myocardial ischemia, regional blood flow and function are proportionally reduced. With prolongation of ischemia, function further declines at unchanged blood flow. We studied the involvement of an inflammatory signal cascade in such progressive dysfunction and whether dysfunction is intrinsic to cardiomyocytes. In 10 pigs, ischemia was induced by adjusting inflow into the cannulated left anterior coronary artery to reduce coronary arterial pressure to 45 mm Hg (ISCH); 4 pigs received the inducible nitric oxide synthase (iNOS) inhibitors aminoguanidine or L-N(6)-(1-iminoethyl)-lysine during ISCH (ISCH+iNOS-Inhib); 6 pigs served as controls (SHAM). Anterior (AW) and posterior (PW) systolic wall thickening (sonomicrometry) were measured. After 6 hours, nitric oxide (NO) synthase (NOS) protein expression, NOS activity, and NO metabolites (nitrite/nitrate/nitroso species) were quantified in biopsies isolated from AW and PW. Cardiomyocyte shortening and intracellular calcium (Indo-1 acetoxymethyl ester) were measured without and with the NOS substrate L-arginine (100 micromol/L). In ISCH, AW wall thickening decreased from 42+/-4% (baseline) to 16+/-3% (6 hours). Wall thickening remained unchanged in ISCH-PW and SHAM-AW/PW. NOS2 (iNOS) protein expression and activity, but not NOS3 (endothelial NO synthase), were increased in ISCH-AW and ISCH-PW. iNOS expression correlated with increased nitrite contents. Cardiomyocyte shortening was reduced in ISCH-AW versus SHAM-AW (4.4+/-0.3% versus 5.6+/-0.3%). L-Arginine reduced cardiomyocyte shortening further in ISCH-AW (to 2.8+/-0.2%) and ISCH-PW (3.4+/-0.4% versus 5.4+/-0.4%) but not in SHAM or in ISCH+iNOS-Inhib; intracellular [Ca(2+)] remained unchanged. With L-arginine, in vitro AW cardiomyocyte shortening correlated with in vivo AW wall thickening (r=0.72). In conclusion, sustained regional ischemia induces myocardial iNOS expression in pigs, which contributes to contractile dysfunction at the cardiomyocyte level.     

Blood donation, body iron status and carotid intima-media thickness

Iron could promote free radical formation, which may lead to injury of the arterial wall and atherosclerosis. Blood donation may reduce cardiovascular risk by lowering body iron status. We collected data on blood donation history and intima-media thickness of the common carotid artery (CIMT) in 819 subjects (50-70 years), who were recruited from municipal and blood bank registries in The Netherlands. Serum iron parameters were assessed, including non-transferrin bound iron (NTBI) that has recently been found in conditions of iron overload. Serum ferritin was lower in current donors (n=443; 44 microg/L) than in ex-donors (n=120; 114 microg/L) and never-donors (n=256; 124 microg/L, P for trend <0.001). For NTBI, values were 2.33, 2.54, and 2.51 micromol/L, respectively (P<0.05). CIMT was slightly reduced in frequent donors (i.e., > or =49 times during life or > or =2 times per year), although not statistically significant. CIMT was not significantly related to NTBI. Frequent blood donation, resulting in lowered body iron, might give some protection against accelerated atherosclerosis.     

Risk prediction of coronary heart disease based on retinal vascular caliber (from the Atherosclerosis Risk In Communities [ARIC] Study)

Recent studies showed that such retinal vascular signs as quantitative retinal vascular caliber were associated with increased risk of incident coronary heart disease (CHD), but whether these retinal vascular signs add to the prediction of CHD over and above traditional CHD risk factors was not addressed. Whether these signs add to the prediction of CHD over and above the Framingham risk score in people (n = 9,155) without diabetes selected from the ARIC Study was investigated. Incident CHD was ascertained using standardized methods, and retinal vascular caliber and other retinal signs were measured from retinal photographs. After a mean of 8.8 years of follow-up, there were 700 incident CHD events. Women with wider retinal venular caliber (hazard ratio 1.27/1-SD increase, 95% confidence interval 1.08 to 1.50) and narrower retinal arteriolar caliber (hazard ratio 1.31/1-SD decrease, 95% confidence interval 1.10 to 1.56) had a higher risk of incident CHD after adjusting for Framingham risk score variables. Area under the receiver operator characteristic curve increased from 0.695 to 0.706 (1.7% increase) with the addition of retinal vascular caliber to the Framingham risk model. Risk prediction models with and without retinal vascular caliber both fitted the data and were well calibrated for women. In men, retinal vascular caliber was not associated with CHD risk after adjustment. Other retinal vascular signs were not associated with 10-year incident CHD in men or women. In conclusion, although retinal vascular caliber independently predicted CHD risk in women, the incremental predictive ability over that of the Framingham model was modest and unlikely to translate meaningfully into clinical practice.