High levels of asymmetric dimethylarginine are strongly associated with low HDL in patients with acute myocardial infarction.

OBJECTIVES: Low levels of high-density lipoprotein (HDL) cholesterol are associated with an increased risk of acute myocardial infarction possibly through impaired endothelial atheroprotection and decreased nitric oxide (NO) bioavailability. Asymmetric dimethylarginine (ADMA) mediates endothelial function by inhibiting nitric oxide synthase activity. In patients with acute myocardial infarction, we investigated the relationship between serum levels of HDL and ADMA. APPROACH AND RESULTS: Blood samples from 612 consecutive patients hospitalized for acute MI <24 hours after symptom onset were taken on admission. Serum levels of ADMA, its stereoisomer, symmetric dimethylarginine (SDMA) and L-arginine were determined using high-performance liquid chromatography. Patients with low HDL (<40 mg/dL for men and <50 mg/dL for women) were compared with patients with higher HDL. Most patients (59%) had low HDL levels. Median ADMA levels were markedly higher in the low HDL group (0.69 vs. 0.50 µmole/L, p<0.001). In contrast, SDMA and L-arginine levels were similar for the two groups (p = 0.120 and p = 0.064). Notably, ADMA, but not SDMA or L-arginine, was inversely correlated with HDL (r = -0.311, p<0.001). In stratified analysis, this relationship was only found for low HDL levels (r = -0.265, p<0.001), but not when HDL levels were higher (r = -0.077, p = 0.225). By multivariate logistic regression analysis, ADMA level was strongly associated with low HDL levels (OR(95%CI):6.06(3.48-10.53), p<0.001), beyond traditional confounding factors. CONCLUSIONS: Our large population-based study showed for the first time a strong inverse relationship between HDL and ADMA in myocardial infarction patients, suggesting a functional interaction between HDL and endothelium, beyond metabolic conditions associated with low HDL levels.

Combining sirolimus-eluting stents and external irradiation in cholesterol-fed rabbits increased incomplete stent apposition and decreased re-endothelialization.

Restenosis after the implantation of a drug-eluting stent or after vascular irradiation therapy shares similar physiopathological mechanisms. No experimental data are currently available on vascular wall behavior after external irradiation on arteries stented with sirolimus-eluting stents (SES). Ten New Zealand white rabbits received a 0.5% cholesterol-enriched chow for 1 month. Bilateral iliac artery stent implantation was then performed with an SES (Cypher; Cordis Corp). The animals were randomized into either an irradiated group (I, 2 Gy external x-ray irradiation, n = 5) or a control group (C, n = 5). The cholesterol-enriched chow was continued for 1 additional month after stent implantation. The stented arteries were harvested for histological analyses. The number and the percentage of incompletely apposed stents struts (IASS) were significantly higher in irradiated versus control group (3.05 +/- 0.46 vs. 1.57 +/- 0.27 IASS, P < 0.01, and 28.44% +/- 3.97% vs. 15.2% +/- 2.46% of IASS, P < 0.01, respectively). The mean neointimal thickness behind the IASS was also higher in the irradiated group (I: 28.3 +/- 2.5 microm vs. C: 18.2 +/- 2.3 microm, P < 0.01). Re-endothelialization was lower in irradiated group (I: 44.6% +/- 17.5% vs. C: 75.2% +/- 5.7%, P < 0.01). The present study revealed that low-dose external irradiation increased incomplete stent apposition and reduced re-endothelialization of SES. These results underscore the potential deleterious cumulative side effects of these 2 procedures to prevent restenosis.

Anti-hypertensive effects of Rosuvastatin are associated with decreased inflammation and oxidative stress markers in hypertensive rats.

Among their pleiotropic effects, statins exert antioxidant and anti-inflammatory properties. The aim of this study was to evaluate in normotensive (WKY) and in spontaneously hypertensive rats (SHR) the effect of rosuvastatin (ROSU) treatment on (1) plasma inflammation markers and endogenous NO synthase inhibitor (ADMA) levels, (2) reactive oxygen species (ROS) generated by circulating leukocytes and (3) vascular oxidative stress and tissue inflammation markers. Plasma cytokines were higher in SHR than in WKY, except for IL-4, which was lower in SHR than in WKY. SHR monocytes exhibited higher production of ROS than did WKY monocytes. In the experimental conditions, ROSU did not modify plasma cholesterol levels in SHR but attenuated the increase in systolic blood pressure. In SHR only, ROSU lessened pro-inflammatory cytokines and ADMA levels, increased IL-4 and reduced ROS production in circulating monocytes. These results demonstrate the beneficial effects of ROSU in SHR, independently of any lowering of cholesterol levels.

Impact of asymmetric dimethylarginine on mortality after acute myocardial infarction.

OBJECTIVE: Asymmetrical dimethylarginine (ADMA) is an endogenous competitive inhibitor of nitric oxide (NO) synthases. From a prospective cohort of patients with acute myocardial infarction (MI), we aimed to analyze the predictive value of circulating ADMA concentrations on prognosis. METHODS AND RESULTS: Blood samples from 249 consecutive patients hospitalized for acute MI <24 hours were taken on admission. Serum levels of ADMA and its stereoisomer, symmetrical dimethylarginine (SDMA), were determined using high-performance liquid chromatography. The independent predictors of ADMA were glomerular filtration rate, female sex, and SDMA (R(2)=0. 25). Baseline ADMA levels were higher in patients who had died than in patients who were alive at 1 year follow-up (1.23 [0.98 to 1.56] versus 0.95 [0.77 to 1.20] micromol/L, P<0.001). By Cox multivariate analysis, the higher tertile of ADMA (median [interquartile range]: 1.45 [1.24 to 1.70] micromol/L) was a predictor for mortality (Hazard Ratio [95% CI], 4.83 [1.59 to 14.71]), when compared to lower tertiles, even when adjusted for potential confounders, such as acute therapy, biological, and clinical factors. CONCLUSIONS: Our study suggests that the baseline ADMA level has a strong prognostic value for mortality after MI, beyond traditional risk factors and biomarkers.

Increase in Levels of BDNF is Associated with Inflammation and Oxidative Stress during Cardiopulmonary Bypass.

Cardiopulmonary Bypass (CPB) is thought to generate reactive oxygen species associated with a systemic inflammation and neurotrophins seem to be involved in cardiovascular inflammatory reactions. The aim of this study was to determine the impact of CPB on plasma neurotrophins levels and to appreciate the links existing between inflammation, oxidative stress and neurotrophins. Blood samples were taken from 27 patients undergoing cardiac surgery: before CPB, during ischemia and at reperfusion under CPB. Oxidative stress was evaluated using an Electron Spin Resonance technique by superoxide detection, and antioxidant defences by measurement of Endogenous Peroxidase Activity (EPA). The evolution of two neurotrophins: Brain Derived Neurotrophic Factor (BDNF) and Nerve Growth Factor (NGF) was assessed with an ELISA method. An inflammatory index was determined by a multiplex flow cytometry method. The inflammatory index showed that MCP-1, P-selectin, t-PA and interleukins 6, 8 and 10 levels increased during CPB (p<0.05). Superoxide production and EPA were higher during ischemia and reperfusion than before CPB (p<0.05). BDNF plasma levels were higher at reperfusion (p<0.05). NGF levels did not change. Our study shows an increase of BDNF levels, associated with an inflammatory phenomenon and a redox modification, in the plasma of patients undergoing cardiac surgery under CPB. The role played by this neurotrophin in this complex situation still needs to be elucidated, in particular its cellular origin. It is also necessary to understand whether BDNF has a beneficial or deleterious effect during CPB.

Asymmetric dimethylarginine (ADMA) and hyperhomocysteinemia in patients with acute myocardial infarction.

OBJECTIVES: We sought to investigate the association between increased levels of asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, and total plasma homocysteinemia (tHcy) in patients with acute myocardial infarction (AMI). DESIGN AND METHODS: In 138 patients hospitalized for AMI <24 h on admission, serum levels of ADMA, its symmetric stereoisomer (SDMA) and tHcy were measured. RESULTS: ADMA was positively associated with SDMA (p<0.001) and tHcy (p=0.03) but not with estimated glomerular filtration rates (eGFR, p=0.96), while tHcy strongly correlated with eGFR (p=0.002) and SDMA (p<0.001). By multiple linear regression, SDMA but not ADMA was independently associated with tHcy (p=0.005). CONCLUSION: Our findings suggest that, in AMI patients, hyperhomocysteinemia is indirectly related to ADMA levels via renal function. Moreover, ADMA level was independent of traditional cardiovascular risk factors in AMI patients. Interestingly, our findings suggest that SDMA could be a good risk indicator for cardiovascular disease in AMI patients.

Short-term atorvastatin treatment does not modify neointimal morphology but reduces MMP-2 expression in normocholesterolemic rabbit stented arteries.

The aim of our study was to explore some potential pleïotropic effects of atorvastatin, after stenting in the iliac arteries of normocholesterolemic rabbits. On day 0, 27 rabbits underwent stent implantation and were randomized into either the control group (standard chow, CTRL, n = 15) or the atorvastatin group (10 mg/kg/d per os, Ator, n = 12). On day 30, the stented arteries were harvested for histomorphometry and neointimal analysis [macrophages, matrix metalloproteinases (MMP-2), tissue inhibitor of metalloproteinase-2, vascular smooth muscle cells, and collagen]. Atorvastatin did not induce significant histomorphometric and inflammatory modifications but reduced neointimal expression of MMP-2 with no modification of tissue inhibitor of metalloproteinase-2, and also induced higher neointimal collagen content (Ator vs. CTRL: MMP-2: 0.05 +/- 0.03 vs. 0.70 +/- 0.20, P < 0.01; collagen: 17.0+/-0.7%/mm vs. 12.0 +/- 1.2%/mm(2) P < 0.01). Atorvastatin treatment also induced a significant decrease in neointimal vascular smooth muscle cells and cellular density (respectively: 2.0 +/- 0.2 vs. 1.4 +/- 0.2, P < 0.05; 5406 +/- 241 nuclei/mm(2) vs. 4402 +/- 163 nuclei/mm(2), P < 0.001). Our study provides new insights into the field of MMP response to stenting and the effects of statin therapy, which could have important implications in the field of in-stent restenosis.