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Congenital long- or short-QT syndrome may lead to life-threatening ventricular tachycardia and sudden cardiac death. Apart from the rare disease-causing mutations, common genetic variants in CAPON, a neuronal nitric oxide synthase (NOS1) regulator, have recently been associated with QT interval variations in a human whole-genome association study. CAPON had been unsuspected of playing a role in cardiac repolarization; indeed, its physiological role in the heart (if any) is unknown. To define the biological effects of CAPON in the heart, we investigated endogenous CAPON protein expression and protein-protein interactions in the heart and performed electrophysiological studies in isolated ventricular myocytes with and without CAPON overexpression. We find that CAPON protein is expressed in the heart and interacts with NOS1 to accelerate cardiac repolarization by inhibition of L-type calcium channel. Our findings provide a rationale for the association of CAPON gene variants with extremes of the QT interval in human populations. [ABSTRACT FROM AUTHOR]

Introduction: Cellular mechanisms of adenosine include a direct effect on the activation of the adenosine-sensitive potassium current (I[sub K,Ado] ) and an indirect effect on antagonism of catecholamine-stimulated adenylate cyclase activity. However, previous studies evaluating the influence of catecholamine activity on the electrophysiologic effects of adenosine have yielded conflicting results. We tested the hypotheses that if adenosine exerts its atrioventricular (AV) nodal blocking effects directly by activating the I[sub K,Ado] potassium current, rather than indirectly by reversing the catecholamine effects, then pretreatment with β-adrenergic blockade would not potentiate the effects of adenosine in terminating AV nodal-dependent supraventricular tachycardia (SVT). Methods and Results: During sustained AV nodal reentrant tachycardia (AVNRT) or AV reentrant tachycardia (AVRT) in 28 patients, adenosine was rapidly injected in incremental doses of 1.5, 3, 6, 9, 12 and 18 mg to determine the lowest effective dose required for tachycardia termination before and immediately after the end of esmolol infusion. Esmolol infusion was started with loading doses of 500 μg/kg/min for 1 min and 150 μg/kg/min for 4 min, followed by a maintenance infusion of 50–100 μg/kg/min. Esmolol infusion was continued until the tachycardia was terminated or the maximal dose of 100 mg was reached. Adenosine was effective in terminating SVT in all 28 patients with a mean lowest effective dose of 96 ± 54 μg/kg before esmolol. During esmolol infusion, tachycardia was reproducibly terminated in 8 patients (6 with AVNRT, 2 with AVRT) with a mean dose of 67 ± 23 mg. In the other 20 patients with persistent tachycardia after 100 mg of esmolol infusion, the lowest effective dose of adenosine could be determined in 19 patients. In the remaining patient with AVRT, the maximal dose of adenosine (18 mg) was unable to terminate the tachycardia immediately after the end of esmolol infusion. In these 19 patients, esmolol infusion caused significant lengthening of the tachycardia cycle length from 338 ± 36 to 372 ± 51 ms (p < 0.0001) and reduction of the mean arterial blood pressure from 96 ± 15 to 88 ± 18 mm Hg (p = 0.034). Compared to the dosage that was determined before esmolol infusion, the lowest effective dose of adenosine remained the same in 13 patients after the end of esmolol infusion, whereas the dose increased in 5 and decreased in 1 patient. The mean lowest effective dose of adenosine was not significantly different before (98 ± 54 μg/kg) and immediately after (115 ± 56 μg/kg) the end of esmolol infusion (p = 0.054). Conclusions: Intravenous esmolol infusion (up to 100 mg total dose) usually fails to terminate AV nodal-dependent SVT. In the esmolol-resistant tachycardia, esmolol pretreatment does not produce a positive synergistic effect on the efficacy of adenosine-induced termination of SVT. Therefore, in this tachycardia adenosine may exert its effects on AV nodal conduction directly by activation of the I[sub K,Ado] potassium current, rather than by antagonizing the β-adrenergic system.Copyright © 2002 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Enhanced advanced glycation end products deposition within myocardial tissue may cause diastolic dysfunction. However, whether this is related to left ventricular hypertrophy or inappropriate left ventricular mass remains unclear. Methods: We prospectively enrolled 139 subjects at risk for cardiovascular diseases. We used echocardiography for measurements of left ventricular mass and cardiac systolic and diastolic functional parameters. An advanced glycation end product reader was applied for measurements of skin autofluorescence values. Comparisons of left ventricular mass and echocardiographic parameters between the higher and lower skin autofluorescence groups were analyzed. Results: Compared with the lower skin autofluorescence group, left ventricular mass index and the ratio of observed left ventricular mass/predicted left ventricular mass (oLVM/pLVM) was significantly higher in the higher skin autofluorescence group (61.22 ± 17.76 vs. 47.72 ± 11.62, P < 0.01, 1.62 ± 0.38 vs. 1.21 ± 0.21, P < 0.01). After adjustment for potential confounding factors, skin autofluorescence was an independent factor for left ventricular mass index (β = 0.32, P < 0.01) and the ratio of oLVM/pLVM (β = 0.41, P < 0.01). Skin autofluorescence ≥2.35 arbitrary unit predicted left ventricular hypertrophy at a sensitivity of 58.8%, and a specificity of 73.0% (P < 0.01). Skin autofluorescence ≥2.25 arbitrary unit predicted inappropriate left ventricular mass at a sensitivity of 71.1%, and a specificity of 83.9% (P < 0.01). Skin autofluorescence was positively correlated with E/E', an indicator for diastolic dysfunction (r = 0.21, P = 0.01). Conclusions: Skin autofluorescence is a useful tool for detecting left ventricular hypertrophy, inappropriate left ventricular mass and diastolic dysfunction. [ABSTRACT FROM AUTHOR]

L5, the most electronegative and atherogenic subfraction of low-density lipoprotein (LDL), induces platelet activation. We hypothesized that plasma L5 levels are increased in acute ischemic stroke patients and examined whether lectin-like oxidized LDL receptor-1 (LOX-1), the receptor for L5 on endothelial cells and platelets, plays a critical role in stroke. Because amyloid β (Aβ) stimulates platelet aggregation, we studied whether L5 and Aβ function synergistically to induce prothrombotic pathways leading to stroke. Levels of plasma L5, serum Aβ, and platelet LOX-1 expression were significantly higher in acute ischemic stroke patients than in controls without metabolic syndrome (P < .01). In mice subjected to focal cerebral ischemia, L5 treatment resulted in larger infarction volumes than did phosphate-buffered saline treatment. Deficiency or neutralizing of LOX-1 reduced infarct volume up to threefold after focal cerebral ischemia in mice, illustrating the importance of LOX-1 in stroke injury. In human platelets, L5 but not L1 (the least electronegative LDL subfraction) induced Aβ release via IκB kinase 2 (IKK2). Furthermore, L5+Aβ synergistically induced glycoprotein IIb/IIIa receptor activation; phosphorylation of IKK2, IκBa, p65, and c-Jun N-terminal kinase 1; and platelet aggregation. These effects were blocked by inhibiting IKK2, LOX-1, or nuclear factor-κB (NF-κB). Injecting L5+Aβ shortened tail-bleeding time by 50% (n = 12; P < .05 vs L1-injected mice), which was prevented by the IKK2 inhibitor. Our findings suggest that, through LOX-1, atherogenic L5 potentiates Aβ-mediated platelet activation, platelet aggregation, and hemostasis via IKK2/NF-κB signaling. L5 elevation may be a risk factor for cerebral atherothrombosis, and downregulating LOX-1 and inhibiting IKK2 may be novel antithrombotic strategies. [ABSTRACT FROM AUTHOR]

Objectives Chronic inflammatory disease may trigger vascular atherosclerosis. This study aimed to determine whether chronic osteomyelitis (COM) is linked to an increased risk of coronary heart disease (CHD). Methods A national insurance claim dataset of more than 23 million enrolees was used to identify 15 054 patients with newly diagnosed COM and 60 216 randomly selected age-matched and gender-matched controls between 2001 and 2009 for comparing the risk and incidence of CHD. The study period was from the entry date to the first date of the following events: the diagnosis of CHD, death, withdrawal from the Taiwan National Health Insurance programme or the end of 2010. The analysis of the CHD risk was performed using Cox proportional hazards regression model. Results During a follow-up period of 67 927 personyears, the overall incidence rate of CHD in COM cohort was 1.95 times higher than non-COM cohort (16.66 vs 8.52 per 1000 person-years). After controlling age, gender and four comorbidities (hypertension, diabetes, hyperlipidaemia and stroke), the risk remained significantly higher in the COM cohort than the control group (adjusted HR=1.65, 95% CI 1.54 to 1.78, p<0.001). In age-stratified analysis, the younger population had a stronger association between COM and CHD risk than the elderly (from HR=3.42, 95% CI 1.60 to 7.32 in age <35 to HR 1.39, 95% CI 1.15 to 1.68 in age ≥ 80). Conclusions This study demonstrates that COM is an independent risk factor for CHD, particularly in the younger population. Further studies are necessary to explore the underlying mechanisms linking COM and CHD. [ABSTRACT FROM AUTHOR]

Background: Increased levels of the most electronegative type of LDL, L5, have been observed in the plasma of patients with metabolic syndrome (MetS) and ST-segment elevation myocardial infarction and can induce endothelial dysfunction. Because men have a higher predisposition to developing coronary artery disease than do premenopausal women, we hypothesized that LDL electronegativity is increased in men and promotes endothelial damage. Methods: L5 levels were compared between middle-aged men and age-matched, premenopausal women with or without MetS. We further studied the effects of gender-influenced LDL electronegativity on aortic cellular senescence and DNA damage in leptin receptor–deficient (db/db) mice by using senescence-associated–β-galactosidase and γH2AX staining, respectively. We also studied the protective effects of 17β-estradiol and genistein against electronegative LDL–induced senescence in cultured bovine aortic endothelial cells (BAECs). Results: L5 levels were higher in MetS patients than in healthy subjects (P < 0.001), particularly in men (P = 0.001). LDL isolated from male db/db mice was more electronegative than that from male or female wild-type mice. In addition, LDL from male db/db mice contained abundantly more apolipoprotein CIII and induced more BAEC senescence than did female db/db or wild-type LDL. In the aortas of db/db mice but not wild-type mice, we observed cellular senescence and DNA damage, and the effect was more significant in male than in female db/db mice. Pretreatment with 17β-estradiol or genistein inhibited BAEC senescence induced by male or female db/db LDL and downregulated the expression of lectin-like oxidized LDL receptor-1 and tumor necrosis factor-alpha protein. Conclusion: The gender dichotomy of LDL-induced cardiovascular damage may underlie the increased propensity to coronary artery disease in men. [ABSTRACT FROM AUTHOR]

Platelet activation and its interaction with leukocytes play an important role in atherothrombosis. Cardiovascular diseases resulted from atherothrombosis remain the major causes of death worldwide. Gallic acid, a major constituent of red wine and tea, has been believed to have properties of cardiovascular protection, which is likely to be related to its antioxidant effects. Nonetheless, there were few and inconsistent data regarding the effects of gallic acid on platelet function. Therefore, we designed this in vitro study to determine whether gallic acid could inhibit platelet activation and the possible mechanisms. From our results, gallic acid could concentration-dependently inhibit platelet aggregation, P-selectin expression, and platelet-leukocyte aggregation. Gallic acid prevented the elevation of intracellular calcium and attenuated phosphorylation of PKCα/p38 MAPK and Akt/GSK3β on platelets stimulated by the stimulants ADP or U46619. This is the first mechanistic explanation for the inhibitory effects on platelets from gallic acid. [ABSTRACT FROM AUTHOR]

Background: It is well known that familial sick sinus syndrome (SSS) is caused by functional alterations of ion channels and gap junction. Limited information is available on the mechanism of age-related non-familial SSS. Although evidence shows a close link between arrhythmia and the renin-angiotensin system (RAS), it remains to be determined whether the RAS is involved in the pathogenesis of non-familial SSS. Methods: In this study, 113 patients with documented non-familial SSS and 125 controls were screened for angiotensinogen (AGT) and gap junction protein-connexin 40 (Cx40) promoter polymorphisms by gene sequencing, followed by an association study. A luciferase assay was used to determine the transcriptional activity of the promoter polymorphism. The interaction between nuclear factors and the promoter polymorphism was characterized by an electrophoretic mobility shift assay (EMSA). Results: Association study showed the Cx40 -44/+71 polymorphisms are not associated with non-familial SSS; however, it indicated that four polymorphic sites at positions -6, -20, -152, and -217 in the AGT promoter are linked to non-familial SSS. Compared to controls, SSS patients had a lower frequency of the G-6A AA genotype (OR 2.88, 95% CI 1.58-5.22, P = 0.001) and a higher frequency of the G allele at -6 position (OR 2.65, 95% CI 1.54-4.57, P = 0.0003). EMSA and luciferase assays confirmed that nucleotide G at position -6 modulates the binding affinity with nuclear factors and yields a lower transcriptional activity than nucleotide A (P<0.01). Conclusion: G-6A polymorphism, which modulates the transcriptional activity of the AGT promoter, may contribute to nonfamilial SSS susceptibility. [ABSTRACT FROM AUTHOR]

Background: Reactive oxygen species are important mediators exerting toxic effects on various organs during ischemia-reperfusion (IR) injury. We hypothesized that adipose-derived mesenchymal stem cells (ADMSCs) protect the kidney against oxidative stress and inflammatory stimuli in rat during renal IR injury.Methods: Adult male Sprague-Dawley (SD) rats (n = 24) were equally randomized into group 1 (sham control), group 2 (IR plus culture medium only), and group 3 (IR plus immediate intra-renal administration of 1.0 × 106 autologous ADMSCs, followed by intravenous ADMSCs at 6 h and 24 h after IR). The duration of ischemia was 1 h, followed by 72 hours of reperfusion before the animals were sacrificed.Results: Serum creatinine and blood urea nitrogen levels and the degree of histological abnormalities were markedly lower in group 3 than in group 2 (all p < 0.03). The mRNA expressions of inflammatory, oxidative stress, and apoptotic biomarkers were lower, whereas the anti-inflammatory, anti-oxidative, and anti-apoptotic biomarkers were higher in group 3 than in group 2 (all p < 0.03). Immunofluorescent staining showed a higher number of CD31+, von Willebrand Factor+, and heme oxygenase (HO)-1+ cells in group 3 than in group 2 (all p < 0.05). Western blot showed notably higher NAD(P)H quinone oxidoreductase 1 and HO-1 activities, two indicators of anti-oxidative capacity, in group 3 than those in group 2 (all p < 0.04). Immunohistochemical staining showed higher glutathione peroxidase and glutathione reductase activities in group 3 than in group 2 (all p < 0.02)Conclusion: ADMSC therapy minimized kidney damage after IR injury through suppressing oxidative stress and inflammatory response. [ABSTRACT FROM AUTHOR]

The article discusses the case of acute massive pulmonary embolism due to radiofrequency catheter ablation. Death, stroke, complete atrioventricular block, cardiac tamponade, acute myocardial infarction and thromboembolism are the most severe complications associated with radiofrequency catheter ablation. Heparin should reportedly be given to the patient to attain an activated clotting time of 250 to 300 seconds to prevent thromboembolism.