Garcinol Attenuates Lipoprotein(a)-Induced Oxidative Stress and Inflammatory Cytokine Production in Ventricular Cardiomyocyte through α7-Nicotinic Acetylcholine Receptor-Mediated Inhibition of the p38 MAPK and NF-κB Signaling Pathways

Garcinol, a nicotinic acetylcholine receptor (nAChR) antagonist, has recently been established as an anti-inflammation agent. However, the molecular mechanism by which garcinol suppresses inflammation in the context of acute myocardial infarction (AMI) remains unclear. Hypothesis: We hypothesized that the administration of physiological doses of garcinol in mice with isoproterenol-induced AMI decreased the effect of lipoprotein(a) (Lp(a))-induced inflammation both in vivo and in vitro via the α7-nAChRs mediated p38 mitogen-activated protein kinase (MAPK)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) signaling pathway. We analyzed altered reactive oxygen species (ROS) generation, the production of superoxide by mitochondria, cytokine expression patterns, and the role of the p38 MAPK/NF-κB signaling pathway after Lp(a)-stimulated human ventricular cardiomyocyte AC16 cells were treated with increasing doses of garcinol. C-reactive protein (CRP), interleukin (IL)-1β, IL-6, or tumor necrosis factor (TNF)-α production were detected by enzyme-linked immunosorbent assay. The Cell Counting Kit-8 assay was used to evaluate drug cytotoxicity. Western blots and confocal fluorescence microscopy were used to determine altered expression patterns of inflammatory biomarkers. We also examined whether the therapeutic effect of garcinol in AMI was mediated in part by α7-nAChR. Lp(a)-induced inflammatory cardiomyocytes had increased expression of membrane-bound α7-nAChRs in vitro and in vivo. Low-dose garcinol did not affect cardiomyocyte viability but significantly reduced mitochondrial ROS, CRP, IL-1β, IL-6, and TNF-α production in Lp(a)-stimulated cardiomyocytes (p < 0.05). The Lp(a)-induced phosphorylation of p38 MAPKs, CamKII, and NFκB, as well as NFκB-p65 nuclear translocation, was also suppressed (p < 0.05) by garcinol, while the inhibition of p38 MAPK by the inhibitor SB203580 decreased the phosphorylation of extracellular signal-regulated kinase (ERK) and p38 MAPK. Garcinol protected cardiomyocytes by inhibiting apoptosis and inflammation in mice with AMI. Furthermore, garcinol also enhanced the expression of microRNA-205 that suppressed the α7-nAChR-induced p38 MAPK/NF-κB signaling pathway. Garcinol suppresses Lp(a)-induced oxidative stress and inflammatory cytokines by α7-nAChR-mediated inhibition of p38 MAPK/NF-κB signaling in cardiomyocyte AC16 cells and isoproterenol-induced AMI mice.

Association between Coronary Artery Spasm and the risk of incident Diabetes: A Nationwide population-based Cohort Study

Background: Non-diabetic coronary artery spasm (CAS) without obstructive coronary artery disease increases insulin resistance. We investigated the risk of incident type 2 diabetes (diabetes) associated with CAS. Methods: Patient records were retrospectively collected from the Taiwan National Health Insurance Research Database during the period 2000-2012. The matched cohorts consisted of 12,413 patients with CAS and 94,721 patients in the control group. Results: During the entire follow-up, the incidence of newly-diagnosed diabetes was 22.2 events per 1000 person-years in the CAS group and 13.9 events per 1000 person-years in the control group. The increased risk of CAS-related incident diabetes was observed regardless of sex and length of follow-up. The median time to incident diabetes was 2.9 and 3.5 years in the CAS and the control group (P <0.001), respectively, regardless of sex. Although age did not affect the risk of CAS-related incident diabetes, the risk was less apparent in the subgroups of male, dyslipidemia, chronic obstructive pulmonary disease, stroke, gout and medicated hypertension. However, CAS patients aged <50 years compared with patients ≥50 years had a greater risk of incident diabetes in females but not in males. Older CAS patients developed diabetes in a shorter length of time than younger patients. Conclusion: CAS is a risk factor for incident diabetes regardless of sex. However, females aged <50 years have a more apparent risk for CAS-related diabetes than old females, which is not observed in males. The median time of 2.9 years to incident diabetes warrants close follow-up.

Effect of proton pump inhibitors on sympathetic hyperinnervation in infarcted rats: Role of magnesium

The long-term use of proton pump inhibitors (PPIs) has been shown to increase the risk of cardiovascular mortality, however the molecular mechanisms are unknown. Superoxide has been implicated in the regulation of nerve growth factor (NGF), a mediator of sympathetic innervation. The purpose of this study was to determine whether PPIs increase ventricular arrhythmias through magnesium-mediated superoxide production in infarcted rats. Male Wistar rats were randomly assigned to receive vehicle, omeprazole, omeprazole + magnesium sulfate, or famotidine treatment for 4 weeks starting 24 hours after the induction of myocardial infarction by ligating the coronary artery. Increased myocardial superoxide and nitrotyrosine levels were noted post-infarction, in addition to a significant upregulation of NGF expression on mRNA and protein levels. Sympathetic hyperinnervation after infarction was confirmed by measuring myocardial norepinephrine and immunofluorescent analysis. Compared with the vehicle, omeprazole-treated infarcted rats had significantly reduced myocardial magnesium content, increased oxidant production, and increased sympathetic innervation, which in turn increased ventricular arrhythmias. These effects were prevented by the coadministration of magnesium sulfate. In an in vivo study, an omeprazole-induced increase in NGF was associated with a superoxide pathway, which was further confirmed by an ex vivo study showing the attenuation of NGF levels after coadministration of the superoxide scavenger Tiron. Magnesium sulfate did not further attenuate NGF levels compared with omeprazole + Tiron. Our results indicate that the long-term administration of PPIs was associated with reduced tissue magnesium content and increased myocardial superoxide production, which exacerbated ventricular arrhythmias after infarction. Magnesium may be a potential target for PPI-related arrhythmias after infarction.

Activation of the monocytic α7 nicotinic acetylcholine receptor modulates oxidative stress and inflammation-associated development of coronary artery spasm via a p38 MAP-kinase signaling-dependent pathway

OBJECTIVE

Smoking and high-sensitivity C-reactive protein (hs-CRP) are risk factors for coronary artery spasm (CAS), which is characterized by the increased interleukin-6 (IL-6) level and monocyte counts; however, limited data are available regarding the role of cigarette-embedded nicotine in the modulation of monocytic inflammatory activity in CAS.

APPROACH

We investigated and elucidated the putative roles and associations of nicotine, monocytic IL-6, α7 nicotinic acetylcholine receptor (α7-nAChR), and CRP in CAS development.

RESULTS

We demonstrated that a significantly increased α7-nAChR (p = 0.001) and IL-6 (p = 0.0036) messenger RNA (mRNA) expression in the serum of patients with CAS. Serum hs-CRP levels exhibited a strong positive correlation with the monocytic mRNA expression of α7-nAChR (r = 0.71, p < 0.001) and IL-6 (r = 0.49, p = 0.006). The α7-nAChR and IL-6 expression levels of the CAS group were also positively correlated (r = 0.63, p < 0.001). Compared with the untreated controls, THP-1 cells and patient-derived monocytes treated with different concentrations of CRP displayed significantly increased expression levels of α7-nAChR mRNA and protein (p = 0.0054), in a dose-dependent manner. We also demonstrated that compared with the IL-6 expression elicited by CRP alone (p = 0.0489), the CRP-induced rise in monocytic IL-6 mRNA and protein expression in the presence of nicotine (p = 0.0002), is mediated by α7-nAChR activation and the deregulation of the human p38 mitogen-activated protein kinases (MAPK) signaling pathway.

CONCLUSIONS

Our data demonstrate that the elevated monocytic IL-6 and α7-nAChR mRNA and protein expression levels are associated with the interaction between nicotine and CRP positively modulates CAS development. Our study suggests the potential role of α7-nAChR mRNA and/or protein expression as a diagnostic biomarker for CAS.

Inhibitory effect of PDGF-BB and serum-stimulated responses in vascular smooth muscle cell proliferation by hinokitiol via up-regulation of p21 and p53

INTRODUCTION

Vascular smooth muscle cell (VSMC) proliferation plays a major role in the progression of vascular diseases. In the present study, we established the efficacy and the mechanisms of action of hinokitiol, a tropolone derivative found in Chamaecyparis taiwanensis, Cupressaceae, in relation to platelet-derived growth factor-BB (PDGF-BB) and serum-dependent VSMC proliferation.

MATERIAL AND METHODS

Primary cultured rat VSMCs were pre-treated with hinokitiol and then stimulated by PDGF-BB (10 ng/ml) or serum (10% fetal bovine serum). Cell proliferation and cytotoxicity were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and lactose dehydrogenase assay, respectively. The degree of DNA synthesis was evaluated by BrdU-incorporation measurements and observed using confocal microscopy. Immunoblotting was utilized to determine the protein level of p-extracellular signal-regulated kinase (ERK) 1/2, p-Akt, p-phosphoinositide 3-kinase (PI3K), p-Janus kinase 2 (JAK2), p-p53, and p21^Cip1. The promoter activity of p21 and p53 activity were measured by dual luciferase reporter assay.

RESULTS

Treatment with hinokitiol (1-10 μM) inhibited PDGF-BB and serum-induced VSMC proliferation and DNA synthesis in a concentration-dependent manner. Cytotoxicity was not observed in hinokitiol-treated VSMCs at the studied concentrations. Pre-incubation of VSMCs with hinokitiol did not alter PDGF-BB-induced phosphorylation of ERK1/2, Akt, PI3K or JAK2. Interestingly, hinokitiol induced promoter activity of p21 and p21 protein expression in VSMCs. Furthermore, hinokitiol augmented p53 protein phosphorylation and subsequently led to enhanced p53 activity.

CONCLUSIONS

These data suggest that the anti-proliferative effects of hinokitiol in VSMCs may be mediated by activation of p21 and p53 signaling pathways, and it may contribute to the prevention of vascular diseases associated with VSMC proliferation.

Norcantharidin, a clinical used chemotherapeutic agent, acts as a powerful inhibitor by interfering with fibrinogen-integrin αIIb β3 binding in human platelets

During platelet activation, fibrinogen binds to its specific platelet receptor, integrin α_IIb β₃ , thus completing the final common pathway for platelet aggregation. Norcantharidin (NCTD) is a promising anticancer agent in China from medicinal insect blister beetle. In this study, we provided the evidence to demonstrate NCTD (0.1-1.0 μM) possesses very powerful antiplatelet activity in human platelets; nevertheless, it had no effects on surface P-selectin expression and only slight inhibition on ATP-release reaction in activated platelets. Moreover, NCTD markedly hindered integrin α_IIb β₃ activation by interfering with the binding of FITC-labelled PAC-1. It also markedly reduced the number of adherent platelets and the single platelet spreading area on immobilized fibrinogen as well as clot retraction. Additionally, NCTD attenuated phosphorylation of proteins such as integrin β₃ , Src and FAK in platelets spreading on immobilized fibrinogen. These results indicate that NCTD restricts integrin α_IIb β₃ -mediated outside-in signalling in human platelets. Besides, NCTD substantially prolonged the closure time in human whole blood and increased the occlusion time of thrombotic platelet plug formation and prolonged the bleeding time in mice. In conclusion, NCTD has dual activities, it can be a chemotherapeutic agent for cancer treatment, and the other side it possesses powerful antiplatelet activity for treating thromboembolic disorders.

Nicorandil regulates the macrophage skewing and ameliorates myofibroblasts by inhibition of RhoA/Rho-kinase signalling in infarcted rats

We have demonstrated that ATP-sensitive potassium (K_ATP ) channel agonists attenuated fibrosis; however, the mechanism remained unclear. Since RhoA has been identified as a mediator of cardiac fibrosis, we sought to determine whether the anti-fibrotic effects of K_ATP channel agonists were mediated via regulating macrophage phenotype and fibroblast differentiation by a RhoA/RhoA-kinase-dependent pathway. Wistar male rats after induction of myocardial infarction were randomized to either vehicle, nicorandil, an antagonist of K_ATP channel glibenclamide, an antagonist of ROCK fasudil, or a combination of nicorandil and glibenclamide or fasudil and glibenclamide starting 24 hrs after infarction. There were similar infarct sizes among the infarcted groups. At day 3 after infarction, post-infarction was associated with increased RhoA/ROCK activation, which can be inhibited by administering nicorandil. Nicorandil significantly increased myocardial IL-10 levels and the percentage of regulatory M2 macrophages assessed by immunohistochemical staining, Western blot, and RT-PCR compared with vehicle. An IL-10 receptor antibody increased myofibroblast infiltration compared with nicorandil alone. At day 28 after infarction, nicorandil was associated with attenuated cardiac fibrosis. These effects of nicorandil were functionally translated in improved echocardiographically derived cardiac performance. Fasudil showed similarly increased expression of M2 macrophages as nicorandil. The beneficial effects of nicorandil on fibroblast differentiation were blocked by adding glibenclamide. However, glibenclamide cannot abolish the attenuated fibrosis of fasudil, implying that RhoA/RhoA-kinase is a downstream effector of K_ATP channel activation. Nicorandil polarized macrophages into M2 phenotype by inhibiting RhoA/RhoA-kinase pathway, which leads to attenuated myofibroblast-induced cardiac fibrosis after myocardial infarction.

Anti-embolic effect of Taorenchengqi Tang in rats with embolic stroke induced by occluding middle cerebral artery

OBJECTIVE

To investigate the anti-embolic effect of Taorenchengqi Tang (TRCQT), a formulas from Traditional Chinese Medicine, plus aspirin in rats with embolic stroke induced by selective occlusion of the middle cerebral artery (MCA). Possible side effects of hemorrhagic incident and other bleeding events and anti-platelet effect were also explored.

METHODS

Ninety rats were randomly separated into 9 groups (n = 10): group 1 a sham-operated group (n = 10); groups 2 and 3 orally treated with an isovolumetric solvent (distilled water) for 1 and 3 months, followed by thromboembolic occlusion (n = 10); groups 4 and 5 orally treated with aspirin (5 mg/kg) alone for 1 and 3 months, followed by thromboembolic occlusion (n = 10); groups 6 and 7 orally treated with TRCQT (0.5 g/kg) alone for 1 and 3 months, followed by thromboembolic occlusion (n = 10); groups 8 and 9 orally treated with TRCQT plus aspirin for 1 and 3 months, respectively followed by thromboembolic occlusion (n = 10). The ischemic stroke in rats was induced by selective MCA occlusion. One was orally administered. After the treatments, rats' brains were removed, sectioned and stained with triphenyltetrazolium chloride (TTC) for infarct volume measurement. The incidence of subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH) were observed. A potential gastric bleeding side effect was assessed by measuring hemoglobin (Hb), and prothrombin time (PT). Collagen-induced platelet activation and tail vein bleeding time were measured.

RESULTS

Treatment with TRCQT alone or in combination with aspirin reduced infarct volume for 1 (P < 0.05), and 3 (P < 0.01) months without SAH and ICH incidences, and gastric bleeding. TRCQT treatment for 1 month was also not altered PT. Moreover, a concentration dependent inhibition of collagen-induced platelet activation, followed by increasing of tail vein bleeding time was observed after TRCQT treatment.

CONCLUSION

Either TRCQT alone or TRCQT plus aspirin exhibits potent neuroprotective effect by reducing infarct volume without changing the status of SAH, ICH and gastric bleeding possibly via inhibiting the platelet activation and increasing bleeding time.

Inhibition of infarction-induced sympathetic innervation with endothelin receptor antagonism via a PI3K/GSK-3β-dependent pathway

Although endothelin (ET)-1 has been shown to upregulate nerve growth factor (NGF) expression, the molecular mechanisms are largely unknown. Phosphatidylinositol 3-kinase (PI3K)/Akt/glycogen synthase kinase (GSK)-3β signal has been implicated in the regulation of NGF. We investigated whether selective ET receptor blockers attenuated cardiac sympathetic reinnervation through restoring PI3K/Akt/GSK-3β activity. After ligation of the left anterior descending artery, male Wistar rats were randomized to either vehicle, atrasentan (an ET_A receptor antagonist) or A-192621 (an ET_B receptor antagonist) for 4 weeks. Sympathetic hyperinnervation after infarction was confirmed by myocardial norepinephrine measurement and immunofluorescent analysis. Post infarction was associated with increased reactive oxygen species (ROS), as measured by myocardial superoxide levels and dihydroethidine fluorescence staining. This was paralleled by a significant upregulation of NGF expression on mRNA and protein levels in the vehicle-treated rats, which reduced after administering atrasentan, not A-192621. Arrhythmic scores in the vehicle-treated rats were significantly higher than those treated with atrasentan. In an in vivo study atrasentan-induced decreased NGF was associated with activation of PI3K/Akt signaling pathway, which was further confirmed by the ex vivo study showing the restoration of NGF levels after coadministration of PI3K inhibitors (wortmannin and LY294002). Lithium chloride, an inhibitor of GSK-3β, did not provide additional attenuated NGF levels compared with atrasentan alone. Finally, atrasentan-attenuated NGF levels were reversed in the presence of peroxynitrite generator. ET_A receptor antagonism is a mediator to attenuate sympathetic hyperinnervation probably through restoration of PI3K/Akt/GSK-3β/ROS signaling pathway, a potential pharmacological target for arrhythmias after infarction.

Dapagliflozin, a selective SGLT2 Inhibitor, attenuated cardiac fibrosis by regulating the macrophage polarization via STAT3 signaling in infarcted rat hearts

During myocardial infarction, infiltrated macrophages have pivotal roles in cardiac remodeling and delayed M1 toward M2 macrophage phenotype transition is considered one of the major factors for adverse ventricular remodeling. We investigated whether dapagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, attenuates cardiac fibrosis via regulating macrophage phenotype by a reactive oxygen and nitrogen species (RONS)/STAT3-dependent pathway in postinfarcted rats. Normoglycemic male Wistar rats were subjected to coronary ligation and then randomized to either saline, dapagliflozin (a specific SGLT2 inhibitor), phlorizin (a nonspecific SGLT1/2 inhibitor), dapagliflozin + S3I-201 (a STAT3 inhibitor), or phlorizin + S3I-201 for 4 weeks. There were similar infarct sizes among the infarcted groups at the acute and chronic stages of infarction. At day 3 after infarction, post-infarction was associated with increased levels of superoxide and nitrotyrosine, which can be inhibited by administering either dapagliflozin or phlorizin. SGLT2 inhibitors significantly increased STAT3 activity, STAT3 nuclear translocation, myocardial IL-10 levels and the percentage of M2 macrophage infiltration. At day 28 after infarction, SGLT2 inhibitors were associated with attenuated myofibroblast infiltration and cardiac fibrosis. Although phlorizin decreased myofibroblast infiltration, the effect of dapagliflozin on attenuated myofibroblast infiltration was significantly higher than phlorizin. The effects of SGLT2 inhibitors on cardiac fibrosis were nullified by adding S3I-201. Furthermore, the effects of dapagliflozin on STAT3 activity and myocardial IL-10 levels can be reversed by 3-morpholinosydnonimine, a peroxynitrite generator. Taken together, these observations provide a novel mechanism of SGLT2 inhibitors-mediated M2 polarization through a RONS-dependent STAT3-mediated pathway and selective SGLT2 inhibitors are more effective in attenuating myofibroblast infiltration during postinfarction remodeling.

The neuroprotective effects of Tao-Ren-Cheng-Qi Tang against embolic stroke in rats

Background

Combinations of the traditional Chinese and Western medicines have been used to treat numerous diseases throughout the world, and there is a growing body of evidence showing that some of the herbs used in traditional Chinese medicine elicit significant pharmacological effects. The aim of this study was to demonstrate the neuroprotective effects of Tao-Ren-Cheng-Qi Tang (TRCQT) in combination with aspirin following middle cerebral artery occlusion (MCAO)—induced embolic stroke in rats.

Methods

A blood clot was embolized into the middle cerebral artery of rats to induce focal ischemic brain injury. After 24 h of MCAO occlusion, the rats were arbitrarily separated into five groups and subjected to different oral treatment processes with TRCQT and aspirin for 30 days before being evaluated in terms of their neurological behavior using a four-point system. The rats were sacrificed at 30 days after drug treatment and the infarct volumes were measured using a 2,3,5-triphenyltetrazolium chloride staining method. Tumor necrosis factor-α (TNF-α), c-Jun N-terminal kinases (JNK), activated caspase-3 and Bax were detected by western blot analysis. The apoptotic cells were identified by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. ROS generation was also measured by electron spin resonance spectrometry.

Results

Rats treated with TRCQT alone or in combination with aspirin showed a significantly reduced infarct volume (P < 0.001) and improved neurological outcome compared with those treated with distilled water. Rats treated with TRCQT alone (P = 0.021) or in combination with aspirin (P = 0.02) also showed significantly reduced MCAO-induced expression levels of TNF-α and pJNK (P < 0.001) in their ischemic regions. Rats treated with TRCQT alone or in combination with aspirin showed decreased apoptosis by a reduction in the number of TUNEL positive cells, which inhibited the expression of activated caspase-3 (P = 0.038) and Bax (P = 0.004; P = 0.003). TRCQT also led to a significant concentration-dependent reduction in the formation of hydroxyl radicals (P < 0.001).

Conclusions

TRCQT reduced brain infarct volume and improved neurological outcomes by reducing apoptosis, attenuating the expression of TNF-α and p-JNK, and reducing the formation of hydroxyl radicals in MCAO-induced embolic stroke of rats.

Electronic supplementary material

The online version of this article (doi:10.1186/s13020-017-0128-y) contains supplementary material, which is available to authorized users.

Arterial Stiffness Index and Coronary Artery Plaques in Patients with Subclinical Coronary Atherosclerosis

BACKGROUND

Arterial stiffness is a physiologic quantitative value used to measure arterial compliance. It is predictive of coronary atherosclerosis in patients with intermediate to high cardiovascular risk. However, a correlation between arterial stiffness and subclinical coronary atherosclerosis has yet to be established. Therefore, the purpose of this study was to evaluate arterial stiffness using an arterial stiffness index (ASI) and investigate its association with coronary artery plaque in patients with subclinical coronary atherosclerosis.

METHODS

Our study enrolled 156 consecutive subjects who underwent health screening using a 64-slice cardiac computed tomography angiography (CCTA). Their arterial stiffness index was assessed noninvasively by CardioVision(®) MS-2000. The atheroma on the coronary vessel walls was analyzed.

RESULTS

Of the 156 patients, 53 displayed at least one > 50% stenotic lesion over the coronary arteries in CCTA images. The patients with at least one > 50% coronary stenotic plaque were older and had higher systolic blood pressure and ASI values than patients without > 50% coronary stenotic plaque. After dividing the study population into 2 groups by those patients over and under 50 years of age, the ASI positively correlated with the presentation of at least one > 50% coronary stenotic plaque in patients aged ≥ 50 years (odds ratio = 1.02, 95% confidence interval: 1.00-1.04, p = 0.03).

CONCLUSIONS

The ASI could play a role in risk stratification systems for coronary artery disease in patients with subclinical coronary atherosclerosis, and is a useful clinical marker for the correlation of early coronary plaque.

KEY WORDS

Arterial stiffness; Arterial stiffness index; Atherosclerosis; Coronary artery plaque.

Dipeptidyl peptidase-4 inhibition attenuates arrhythmias via a protein kinase A-dependent pathway in infarcted hearts

BACKGROUND

The effect of dipeptidyl peptidase-4 (DPP-4) inhibitors on arrhythmias remains unknown. The aim of this study was to investigate whether sitagliptin attenuates arrhythmias through inhibiting nerve growth factor (NGF) expression, focusing on cyclic adenosine monophosphate (cAMP) downstream signaling such as protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac).

METHODS AND RESULTS

Male Wistar rats were randomized to either vehicle or sitagliptin for 4 weeks starting 24 h after ligating the coronary artery. Post-infarction was associated with increased oxidative stress. Measurement of myocardial norepinephrine levels revealed a significant elevation in vehicle-treated rats compared with sham. Compared with the vehicle, infarcted rats treated with sitagliptin had significantly increased cAMP levels, decreased DPP-4 activity, oxidative stress, NGF levels and immunofluorescence-stained sympathetic hyperinnervation. Arrhythmic scores were significantly lower in the sitagliptin-treated infarcted rats than in vehicle. Ex vivo studies showed that sitagliptin increased the phosphorylated cAMP response element-binding protein (CREB), which can be reversed by H-89 (a PKA inhibitor), not brefeldin A (an Epac inhibitor).Heme oxygenase-1(HO-1) expression was increased by a PKA agonist but not by an Epac agonist.HO-1expression was attenuated in KG-501 (a CREB inhibitor)-treated infarcted rats in the presence of a PKA agonist.

CONCLUSIONS

Sitagliptin protects ventricular arrhythmias by attenuating NGF-induced sympathetic innervation via upregulation ofHO-1expression in a cAMP/PKA/CREB-dependent antioxidant pathway in non-diabetic infarcted rats.

Comparative decline of the protein profiles of nebulin in response to denervation in skeletal muscle

The sliding filament model of the sarcomere was developed more than half a century ago. This model, consisting only of thin and thick filaments, has been efficacious in elucidating many, but not all, features of skeletal muscle. Work during the 1980s revealed the existence of two additional filaments: the giant filamentous proteins titin and nebulin. Nebulin, a giant myofibrillar protein, acts as a protein ruler to maintain the lattice arrays of thin filaments and plays a role in signal transduction and contractile regulation. However, the change of nebulin and its effect on thin filaments in denervation-induced atrophic muscle remains unclear. The purpose of this study is to examine the content and pattern of nebulin, myosin heavy chain (MHC), actin, and titin in innervated and denervated tibialis anterior (TA) muscles of rats using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), densitometry and electron microscopic (EM) analyses. The results revealed that denervation induced muscle atrophy is accompanied by decreased nebulin content in a time-dependent manner. For instant, the levels of nebulin in denervated muscles were markedly (P < 0.05) decreased, about 24.6% and 40.2% in comparison with innervated muscle after denervation of 28 and 56 days, respectively. The nebulin/MHC, nebulin/actin, and nebulin/titin ratios were decreased, suggesting a concomitant reduction of nebulin in denervated muscle. Moreover, a western blotting assay proved that nebulin declined faster than titin on 28 and 56 days of denervated muscle. In addition, EM study revealed that the disturbed arrangements of myofilaments and a disorganized contractile apparatus were also observed in denervated muscle. Overall, the present study provides evidence that nebulin is more sensitive to the effect of denervation than MHC, actin, and titin. Nebulin decline indeed resulted in disintegrate of thin filaments and shortening of sarcomeres.

Synergistic Impact of Nicotine and Shear Stress Induces Cytoskeleton Collapse and Apoptosis in Endothelial Cells

Nicotine is the major component in cigarette smoke and has been recognized as a risk factor for various cardiovascular diseases such as atherosclerosis. However, the definite pathogenesis of nicotine-mediated endothelial dysfunction remains unclear because hemodynamic factor in most of prior in vitro studies was excluded. To understand how nicotine affects endothelium in the dynamic environment, human umbilical vein endothelial cells were treated by different laminar shear stresses (LSS; 0, 6, 8, and 12 dynes cm(-2)) with and without 10(-4) M nicotine for 12 h in a parallel plate flow system, following detections of cellular morphology and apoptotic level. Our results showed that cells sheared by 12 dynes cm(-2) LSS with nicotine excessively elongated and aligned with the flow direction, and exhibited significant apoptosis as compared to the groups with nicotine or LSS alone. We reasoned that the irregular morphological rearrangement and elevated apoptosis were resulted from the interruption of mechanostasis due to cytoskeletal collapse. Furthermore, all the impaired responses can be rescued by treatment with free radical scavenger ascorbic acid (10(-4) M), indicating oxidative stress was likely mediated with the impairments. In summary, our findings demonstrated an essential role of LSS in nicotine-mediated endothelial injury occurring in the physiological environment.

Inhibition of glycogen synthase kinase-3β prevents sympathetic hyperinnervation in infarcted rats

We have demonstrated that nerve growth factor (NGF) expression in the myocardium is selectively increased during chronic stage of myocardial infarction, resulting in sympathetic hyperinnervation. Glycogen synthase kinase-3 (GSK-3) signal has been shown to play key roles in the regulation of cytoskeletal assembly during axon regeneration. We assessed whether lithium, a GSK-3 inhibitor, attenuates cardiac sympathetic reinnervation after myocardial infarction through attenuated NGF expression and Tau expression. Twenty-four hours after ligation of the anterior descending artery, male Wistar rats were randomized to either LiCl or SB216763, chemically unrelated inhibitors of GSK-3β, a combination of LiCl and SB216763, or vehicle for four weeks. Myocardial norepinephrine levels revealed a significant elevation in vehicle-treated rats compared with sham-operated rats, consistent with excessive sympathetic reinnervation after infarction. Immunohistochemical analysis for sympathetic nerve also confirmed the change of myocardial norepinephrine. This was paralleled by a significant upregulation of NGF protein and mRNA in the vehicle-treated rats, which was reduced after administering either LiCl, SB216763, or combination. Arrhythmic scores during programmed stimulation in the vehicle-treated rats were significantly higher than those treated with GSK-3 inhibitors. Addition of SB216763 did not have additional beneficial effects compared with those seen in rats treated with LiCl alone. Furthermore, lithium treatment increased Tau1 and decreased AT8 and AT180 levels. Chronic use of lithium after infarction, resulting in attenuated sympathetic reinnervation by GSK-3 inhibition, may modify the arrhythmogenic response to programmed electrical stimulation.

MK-0626, a dipeptidyl peptidase-4 inhibitor, improves neovascularization by increasing both the number of circulating endothelial progenitor cells and endothelial nitric oxide synthetase expression

Current treatment modalities for critical limb ischemia (CLI) are of limited benefit; therefore, advances in therapeutic vasculogenesis may open an important new avenue for the treatment of CLI. This study examines the therapeutic potential of the DPP-4 inhibitor MK-0626 as a regulator of vasculogenesis in vivo. MK-0626 was administered daily to C57CL/B6 mice and eGFP-labeled bone marrow-transplanted ICR mice that had undergone hind limb ischemia surgery. Laser Doppler imaging and flow cytometry were used to evaluate the degree of neo-vasculogenesis and the number of circulating endothelial progenitor cells (EPCs), respectively. Cell surface markers of EPCs and the level of endothelial nitric oxide synthase (eNOS) were studied in the vessels. Mice that received MK-0626 had an elevated level of glucagon- like peptide-1 (GLP-1) and a decreased level of dipeptidyl peptidase-4 (DPP-4) in their plasma, in addition to an ischemia-induced increase in the level of stromal cell-derived factor-1 (SDF-1). In C57CL/B6 mice, blood flow in the ischemic limb was significantly improved by treatment with MK-0626. The number of circulating EPCs and both the synthesis and phosphorylation of eNOS were also increased in ischemic thigh muscle after MK-0626 treatment. In contrast, similar effects of MK-0626 were not observed in B6.129P2-Nos3(tm1Unc)/J mice (an eNOS knockout mouse). Additionally, MK-0626 treatment promoted the mobilization and homing of EPCs to ischemic tissue in eGFP transgenic mouse bone marrow-transplanted ICR mice. We conclude that both the number of circulating EPCs and neo-vasculogenesis are increased in response to DPP-4 inhibitor treatment and that this occurs via an eNOS-dependent mechanism. The results highlight the therapeutic vasculogenesis potential of the DPP-4 inhibitor MK-0626 using a hind limb ischemia mouse model.

Antiarrhythmic effect of lithium in rats after myocardial infarction by activation of Nrf2/HO-1 signaling

Glycogen synthase kinase-3 (GSK-3) signaling has been shown to play a role in the regulation of nuclear factor erythroid-2-related factor 2 (Nrf2), a master regulator of antioxidant genes, including heme oxygenase-1 (HO-1). We assessed whether lithium, a GSK-3 inhibitor, attenuates cardiac sympathetic reinnervation after myocardial infarction, a status of high reactive oxygen species (ROS), by attenuating nerve growth factor (NGF) expression and whether Nrf2/HO-1 signaling is involved in the protection. Twenty-four hours after ligation of the left anterior descending artery, male Wistar rats were treated for 4 weeks. The postinfarction period was associated with increased oxidative-nitrosative stress, as measured by myocardial superoxide, nitrotyrosine, and dihydroethidium fluorescent staining. In concert, myocardial norepinephrine levels and immunohistochemical analysis of sympathetic nerve revealed a significant increase in innervation in vehicle-treated rats compared with sham-operated rats. Arrhythmic scores during programmed stimulation in the vehicle-treated rats were significantly higher than those in sham. This was paralleled by a significant upregulation of NGF protein and mRNA in the vehicle-treated rats, which was reduced after administration of LiCl. LiCl stimulated the nuclear translocation of Nrf2 and the transactivation of the Nrf2 target gene HO-1. Inhibition of phosphoinositide 3-kinase by wortmannin reduced the increase in Nrf2 nucleus translocation and HO-1 expression compared with lithium alone. In addition, the lithium-attenuated NGF levels were reversed in the presence of the Nrf2 inhibitor trigonelline, HO-1 inhibitor SnPP, and peroxynitrite generator SIN-1, indicating the role of Nrf2/HO-1/ROS. In conclusion, lithium protects against ventricular arrhythmias by attenuating NGF-induced sympathetic innervation via antioxidant activation of the Nrf2/HO-1 axis.

Sitagliptin attenuates sympathetic innervation via modulating reactive oxygen species and interstitial adenosine in infarcted rat hearts

We investigated whether sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, attenuates arrhythmias through inhibiting nerve growth factor (NGF) expression in post-infarcted normoglycemic rats, focusing on adenosine and reactive oxygen species production. DPP-4 bound adenosine deaminase has been shown to catalyse extracellular adenosine to inosine. DPP-4 inhibitors increased adenosine levels by inhibiting the complex formation. Normoglycemic male Wistar rats were subjected to coronary ligation and then randomized to either saline or sitagliptin in in vivo and ex vivo studies. Post-infarction was associated with increased oxidative stress, as measured by myocardial superoxide, nitrotyrosine and dihydroethidium fluorescent staining. Measurement of myocardial norepinephrine levels revealed a significant elevation in vehicle-treated infarcted rats compared with sham. Compared with vehicle, infarcted rats treated with sitagliptin significantly increased interstitial adenosine levels and attenuated oxidative stress. Sympathetic hyperinnervation was blunted after administering sitagliptin, as assessed by immunofluorescent analysis and western blotting and real-time quantitative RT-PCR of NGF. Arrhythmic scores in the sitagliptin-treated infarcted rats were significantly lower than those in vehicle. Ex vivo studies showed a similar effect of erythro-9-(2-hydroxy-3-nonyl) adenine (an adenosine deaminase inhibitor) to sitagliptin on attenuated levels of superoxide and NGF. Furthermore, the beneficial effects of sitagliptin on superoxide anion production and NGF levels can be reversed by 8-cyclopentyl-1,3-dipropulxanthine (adenosine A₁ receptor antagonist) and exogenous hypoxanthine. Sitagliptin protects ventricular arrhythmias by attenuating sympathetic innervation via adenosine A₁ receptor and xanthine oxidase-dependent pathways, which converge through the attenuated formation of superoxide in the non-diabetic infarcted rats.

Ex vivo and in vivo studies of CME-1, a novel polysaccharide purified from the mycelia of Cordyceps sinensis that inhibits human platelet activation by activating adenylate cyclase/cyclic AMP

INTRODUCTION

CME-1, a novel water-soluble polysaccharide, was purified from the mycelia of Cordyceps sinensis, and its chemical structure was characterized to contain mannose and galactose in a ratio of 4:6 (27.6 kDa). CME-1 was originally observed to exert a potent inhibitory effect on tumor migration and a cytoprotective effect against oxidative stress. Activation of platelets caused by arterial thrombosis is relevant to various cardiovascular diseases (CVDs). However, no data are available concerning the effects of CME-1 on platelet activation. Hence, the purpose of this study was to examine the ex vivo and in vivo antithrombotic effects of CME-1 and its possible mechanisms in platelet activation.

METHODS

The aggregometry, immunoblotting, flow cytometric analysis and platelet functional analysis were used in this study.

RESULTS

CME-1 (2.3-7.6 μM) exhibited highly potent activity in inhibiting human platelet aggregation when stimulated by collagen, thrombin, and arachidonic acid but not by U46619. CME-1 inhibited platelet activation accompanied by inhibiting Akt, mitogen-activated protein kinases (MAPKs), thromboxane B2 (TxB2) and hydroxyl radical (OH(●)) formation. However, CME-1 interrupted neither FITC-triflavin nor FITC-collagen binding to platelets. CME-1 markedly increased cyclic AMP levels, but not cyclic GMP levels, and stimulated vasodilator-stimulated phosphoprotein (VASP) phosphorylation. SQ22536, an inhibitor of adenylate cyclase, but not ODQ, an inhibitor of guanylate cyclase, obviously reversed the CME-1-mediated effects on platelet aggregation and vasodilator-stimulated phosphoprotein (VASP), Akt, p38 MAPK phosphorylation, and TxB2 formation. CME-1 substantially prolonged the closure time of whole blood and the occlusion time of platelet plug formation.

CONCLUSION

This study demonstrates for the first time that CME-1 exhibits highly potent antiplatelet activity that may initially activate adenylate cyclase/cyclic AMP and, subsequently, inhibit intracellular signals (such as Akt and MAPKs), ultimately inhibiting platelet activation. This novel role of CME-1 indicates that CME-1 exhibits high potential for application in treating and preventing CVDs.

Both GPER and membrane oestrogen receptor-α activation protect ventricular remodelling in 17β oestradiol-treated ovariectomized infarcted rats

Clinical and experimental studies have established that gender is a factor in the development of ventricular hypertrophy. We investigated whether the attenuated hypertrophic effect of oestradiol was via activation of phosphatidylinositol 3-kinase (PI3K)/Akt/endothelial nitric oxide synthase (eNOS) through non-genomic action. Twenty-four hours after coronary ligation, female Wistar rats were randomized into control, subcutaneous oestradiol treatment or a G-protein coupled oestrogen receptor (GPER) agonist, G-1 and treated for 4 weeks starting from 2 weeks after bilateral ovariectomy. Ventricular hypertrophy assessed by cardiomyocyte size after infarction was similarly attenuated by oestradiol or G-1 in infarcted rats. The phosphorylation of Akt and eNOS was significantly decreased in infarcted rats and restored by oestradiol and G-1, implying the GPER pathway in this process. Oestradiol-induced Akt phosphorylation was not abrogated by G-15 (a GPER blocker). Akt activation was not inhibited by actinomycin D. When a membrane-impermeable oestrogen-albumin construct was applied, similar responses in terms of eNOS activation to those of oestradiol were achieved. Furthermore, PPT, an ERα receptor agonist, activated the phosphorylation of Akt and eNOS. Thus, membrane ERα receptor played a role in mediating the phosphorylation of Akt and eNOS. The specific PI3K inhibitor, LY290042, completely abolished Akt activation and eNOS phosphorylation in infarcted hearts treated with either oestradiol or oestradiol + G-15. These data support the conclusions that oestradiol improves ventricular remodelling by both GPER- and membrane-bound ERα-dependent mechanisms that converge into the PI3K/Akt/eNOS pathway, unveiling a novel mechanism by which oestradiol regulates pathological cardiomyocyte growth after infarction.

Porphyromonas gingivalis GroEL induces osteoclastogenesis of periodontal ligament cells and enhances alveolar bone resorption in rats

Porphyromonas gingivalis is a major periodontal pathogen that contains a variety of virulence factors. The antibody titer to P. gingivalis GroEL, a homologue of HSP60, is significantly higher in periodontitis patients than in healthy control subjects, suggesting that P. gingivalis GroEL is a potential stimulator of periodontal disease. However, the specific role of GroEL in periodontal disease remains unclear. Here, we investigated the effect of P. gingivalis GroEL on human periodontal ligament (PDL) cells in vitro, as well as its effect on alveolar bone resorption in rats in vivo. First, we found that stimulation of PDL cells with recombinant GroEL increased the secretion of the bone resorption-associated cytokines interleukin (IL)-6 and IL-8, potentially via NF-κB activation. Furthermore, GroEL could effectively stimulate PDL cell migration, possibly through activation of integrin α1 and α2 mRNA expression as well as cytoskeletal reorganization. Additionally, GroEL may be involved in osteoclastogenesis via receptor activator of nuclear factor κ-B ligand (RANKL) activation and alkaline phosphatase (ALP) mRNA inhibition in PDL cells. Finally, we inoculated GroEL into rat gingiva, and the results of microcomputed tomography (micro-CT) and histomorphometric assays indicated that the administration of GroEL significantly increased inflammation and bone loss. In conclusion, P. gingivalis GroEL may act as a potent virulence factor, contributing to osteoclastogenesis of PDL cells and resulting in periodontal disease with alveolar bone resorption.

The role of calpain-myosin 9-Rab7b pathway in mediating the expression of Toll-like receptor 4 in platelets: a novel mechanism involved in α-granules trafficking

Toll-like receptors (TLRs) plays a critical role in innate immunity. In 2004, Aslam R. and Shiraki R. first determined that murine and human platelets express functional TLRs. Additionally, Andonegui G. demonstrated that platelets express TLR4, which contributes to thrombocytopenia. However, the underlying mechanisms of TLR4 expression by platelets have been rarely explored until now. The aim of this study was to identify the mechanism of TLR4 expression underlying thrombin treatment. The human washed platelets were used in this study. According to flowcytometry and western blot analysis, the surface levels of TLR4 were significantly enhanced in thrombin-activated human platelets and decreased by TMB-8, calpeptin, and U73122, but not Y27632 (a Rho-associated protein kinase ROCK inhibitor) indicating that thrombin-mediated TLR4 expression was modulated by PAR/PLC pathway, calcium and calpain. Co-immunoprecipitation (co-IP) assay demonstrated that the interaction between TLR4 and myosin-9 (a substrate of calpain) was regulated by calpain; cleavage of myosin-9 enhanced TLR4 expression in thrombin treated platelets. Transmission electron microscope data indicated that human platelets used α-granules to control TLR4 expression; the co-IP experiment suggested that myosin-9 did not coordinate with Rab7b to negatively regulate TLR4 trafficking in thrombin treated platelets. In summary, phospholipase Cγ-calpain-myosin 9-Rab7b axis was responsible for the mechanism underlying the regulation of TLR4 containing α-granules trafficking in thrombin-stimulated platelets, which was involved in coagulation.

GroEL1, a heat shock protein 60 of Chlamydia pneumoniae, impairs neovascularization by decreasing endothelial progenitor cell function

The number and function of endothelial progenitor cells (EPCs) are sensitive to hyperglycemia, hypertension, and smoking in humans, which are also associated with the development of atherosclerosis. GroEL1 from Chlamydia pneumoniae has been found in atherosclerotic lesions and is related to atherosclerotic pathogenesis. However, the actual effects of GroEL1 on EPC function are unclear. In this study, we investigate the EPC function in GroEL1-administered hind limb-ischemic C57BL/B6 and C57BL/10ScNJ (a toll-like receptor 4 (TLR4) mutation) mice and human EPCs. In mice, laser Doppler imaging, flow cytometry, and immunohistochemistry were used to evaluate the degree of neo-vasculogenesis, circulating level of EPCs, and expression of CD34, vWF, and endothelial nitric oxide synthase (eNOS) in vessels. Blood flow in the ischemic limb was significantly impaired in C57BL/B6 but not C57BL/10ScNJ mice treated with GroEL1. Circulating EPCs were also decreased after GroEL1 administration in C57BL/B6 mice. Additionally, GroEL1 inhibited the expression of CD34 and eNOS in C57BL/B6 ischemic muscle. In vitro, GroEL1 impaired the capacity of differentiation, mobilization, tube formation, and migration of EPCs. GroEL1 increased senescence, which was mediated by caspases, p38 MAPK, and ERK1/2 signaling in EPCs. Furthermore, GroEL1 decreased integrin and E-selectin expression and induced inflammatory responses in EPCs. In conclusion, these findings suggest that TLR4 and impaired NO-related mechanisms could contribute to the reduced number and functional activity of EPCs in the presence of GroEL1 from C. pneumoniae.

Differential effect of phosphodiesterase-3 inhibitors on sympathetic hyperinnervation in healed rat infarcts

BACKGROUND

The effect of phosphodiesterase-3 (PDE-3) inhibitors on arrhythmia remains controversial, so the purpose of this study was to determine their differential effects on sympathetic hyperinnervation and the involved mechanisms in a rat model of myocardial infarction.

METHODS AND RESULTS

After ligating the coronary artery, male Wistar rats were randomized to cilostazol or milrinone, chemically unrelated inhibitors of PDE-3, or vehicle for 4 weeks. The postinfarction period was associated with increased myocardial norepinephrine levels and oxidant release, as measured by myocardial superoxide level and dihydroethidine fluorescence staining. Infarcted rats in the milrinone- and cilostazol-treated groups had favorable ventricular remodeling with similar potency. Compared with milrinone, cilostazol significantly increased interstitial adenosine levels and reduced the production of myocardial cAMP and superoxide. Cilostazol significantly blunted sympathetic hyperinnervation, as assessed by immunofluorescent analysis of sympathetic innervation, and western blotting and real-time quantitative RT-PCR of nerve growth factor. Furthermore, the inhibitory effect of cilostazol on nerve growth factor was reversed by 8-cyclopentyl-1,3-dipropylxanthine, a selective A1 receptor antagonist, and enhanced by tempol administration. In spite of similar arrhythmic vulnerability during programmed stimulation in both the vehicle-and cilostazol-treated groups, cilostazol did not have proarrhythmic effects compared with milrinone.

CONCLUSIONS

Unlike milrinone, cilostazol has therapeutic neutrality in arrhythmias because of adenosine uptake inhibition, which antagonizes the PDE-3-induced increase of sympathetic reinnervation via mediation of an adenosine A1 receptor-mediated antioxidation. 

C-reactive protein for predicting prognosis and its gender-specific associations with diabetes mellitus and hypertension in the development of coronary artery spasm

Background

While hypertension is negatively associated with coronary artery spasm (CAS), scarce data are available on diabetes mellitus in relation to CAS. In addition, outcome prediction in patients with CAS is challenging due to the lack of appropriate biomarkers. Therefore, we sought to identify the roles that gender, high-sensitivity C-reactive protein (hs-CRP), diabetes mellitus and hypertension play in CAS development and prognosis.

Methodology/Prinicpal Findings

Patients (350 women and 547 men) undergoing diagnostic coronary angiography with or without proven CAS but without obstructive stenosis were evaluated at long-term follow-up (median 102 months). Diabetic women and diabetic men with low hs-CRP levels had a low and high risk of CAS (odds ratio [OR]: 0.16, 95% confidence interval [CI]: 0.01–1.88 and OR: 5.02, 95% CI: 1.03–24.54, respectively). The ORs of CAS in both women and men with the highest hs-CRP tertile (>3 mg/L) reduced from 4.41 to 1.45 and 2.98 to 1.52, respectively, if they had diabetes mellitus, and from 9.68 to 2.43 and 2.60 to 1.75, respectively, if they had hypertension. Hypertension had a more negative effect on CAS development in diabetic than non-diabetic women, which was not observed in men. The highest hs-CRP tertile was an independent predictor of adverse outcomes. Patients with the highest hs-CRP tertile had more coronary events than patients with the lowest hs-CRP tertitle (p = 0.021, log-rank test).

Conclusions

Diabetes mellitus contributes to CAS development in men with low hs-CRP levels, but not in women. There are negative effects of diabetes mellitus and hypertension on CAS development in patients with high hs-CRP levels and especially in women. Elevated hs-CRP level independently predicts adverse outcomes.

Subacute bacterial endocarditis presenting as left upper quadrant abdominal pain

Infective endocarditis is a microbial infection of the endocardial surface of the heart. Its symptoms and signs are varied, and include fever, heart murmur, peripheral embolism, and heart failure. The diagnosis of subacute bacterial endocarditis (SBE) is suggested by a history of an indolent process characterized by fever, fatigue, anorexia, and unexplained weight loss. These patients may have had an invasive procedure, such as dental work, or abused intravenous drugs prior to the diagnosis of SBE. Although uncommon, the patients may present with nonspecific symptoms caused by peripheral embolic events. Herein, we report a 25-year-old male diagnosed with SBE, who presented with the unusual symptom of sudden onset of left upper quadrant abdominal pain for 2 days. His clinical history is also discussed.

Combined Framingham Risk Score and Coronary Artery Calcium Score Predict Subclinical Coronary Plaque Assessed by Coronary Computed Tomography Angiogram in Asymptomatic Taiwanese Population

BACKGROUND

We sought to determine the predictive value of the combined traditional Framingham risk score (FRS) and coronary artery calcium score (CACS) for subclinical coronary plaque detected by computed tomography coronary angiogram (CTCA) in asymptomatic subjects.

METHOD

We evaluated 167 asymptomatic Taiwanese subjects (mean age, 57 ± 11.2 years), who underwent CTCA as part of a health evaluation. We examined the associations between FRS, CACS, serum biomarkers, and coronary plaque assessed by CTCA.

RESULTS

Out of 167 subjects in the study, 95 had coronary artery atheroma. Of those possible predictors for coronary atherosclerosis, both FRS and CACS were independent predictors for the presence of coronary plaque [relative risk (RR): 1.29, 95% confidence interval (CI): 1.07-1.54, p = 0.006 and RR: 1.42, 95% CI: 1.16-1.75, p = 0.001, respectively]. Receiver operating characteristics curve analysis revealed that CACS and FRS were indicators of the presence of coronary plaque. The area under the curve for FRS and CACS was 0.729 and 0.889, respectively (p < 0.001). Furthermore, the area under the curve for combination of FRS and CACS was 0.936 (95% CI: 0.887-0.969, p < 0.001), and this combination provided a better diagnostic advantage than either FRS or CACS alone (p < 0.001 and p = 0.012 by C-statistic, respectively).

CONCLUSIONS

In asymptomatic Taiwanese subjects with low to intermediate cardiovascular risk, both FRS and CACS were independently related to subclinical atherosclerosis. A combined FRS and CACS evaluation improved the efficacy of prediction for atherosclerotic plaque burden.

KEY WORDS

Atherosclerosis; Computed coronary tomography angiogram; Coronary artery calcium score; Framingham risk score; Subclinical coronary plaque.

Both PKA and Epac pathways mediate N-acetylcysteine-induced Connexin43 preservation in rats with myocardial infarction

Cardiac remodeling was shown to be associated with reduced gap junction expression after myocardial infarction. A reduction in gap junctional proteins between myocytes may trigger ventricular arrhythmia. Therefore, we investigated whether N-acetylcysteine exerted antiarrhythmic effect by preserving connexin43 expression in postinfarcted rats, focusing on cAMP downstream molecules such as protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac). Male Wistar rats after ligating coronary artery were randomized to either vehicle, or N-acetylcysteine for 4 weeks starting 24 hours after operation. Infarct size was similar between two groups. Compared with vehicle, cAMP levels were increased by N-acetylcysteine treatment after infarction. Myocardial connexin43 expression was significantly decreased in vehicle-treated infarcted rats compared with sham operated rats. Attenuated connexin43 expression and function were blunted after administering N-acetylcysteine, assessed by immunofluorescent analysis, dye coupling, Western blotting, and real-time quantitative RT-PCR of connexin43. Arrhythmic scores during programmed stimulation in the N-acetylcysteine-treated rats were significantly lower than those treated with vehicle. In an ex vivo study, enhanced connexin43 levels afforded by N-acetylcysteine were partially blocked by either H-89 (a PKA inhibitor) or brefeldin A (an Epac-signaling inhibitor) and completely blocked when H-89 and brefeldin A were given in combination. Addition of either the PKA specific activator N6Bz or Epac specific activator 8-CPT did not have additional increased connexin43 levels compared with rats treated with lithium chloride alone. These findings suggest that N-acetylcysteine protects ventricular arrhythmias by attenuating reduced connexin43 expression and function via both PKA- and Epac-dependent pathways, which converge through the inactivation of glycogen synthase kinase-3β.

Dipeptidyl peptidase-4 inhibitor improves neovascularization by increasing circulating endothelial progenitor cells

BACKGROUND AND PURPOSE

Current methods used to treat critical limb ischaemia (CLI) are hampered by a lack of effective strategies, therefore, therapeutic vasculogenesis may open up a new field for the treatment of CLI. In this study we investigated the ability of the DPP-4 inhibitor, sitagliptin, originally used as a hypoglycaemic agent, to induce vasculogenesis in vivo.

EXPERIMENTAL APPROACH

Sitagliptin were administered daily to C57CL/B6 mice and eGFP transgenic mouse bone marrow-transplanted ICR mice that had undergone hindlimb ischaemic surgery. Laser Doppler imaging and flow cytometry were used to evaluate the degree of neovasculogenesis and circulating levels of endothelial progenitor cells (EPCs) respectively. Cell surface markers of EPCs and endothelial NOS (eNOS) in vessels were studied.

KEY RESULTS

Sitagliptin elevated plasma glucagon-like peptide-1 (GLP-1) levels in mice subjected to ischaemia, decreased plasma dipeptidyl peptidase-4 (DPP-4) concentration, and augmented ischaemia-induced increases in stromal cell-derived factor-1 (SDF-1) in a dose-dependent manner. Blood flow in the ischaemic limb was significantly improved in mice treated with sitagliptin. Circulating levels of EPCs were also increased after sitagliptin treatment. Sitagliptin also enhanced the expression of CD 34 and eNOS in ischaemic muscle. In addition, sitagliptin promoted EPC mobilization and homing to ischaemic tissue in eGFP transgenic mouse bone marrow-transplanted ICR mice.

CONCLUSION AND IMPLICATIONS

Circulating EPC levels and neovasculogenesis were augmented by the DPP-4 inhibitor, sitagliptin and this effect was dependent on an eNOS-related pathway in a mouse model of hindlimb ischaemia. The results indicate that oral administration of sitagliptin has therapeutic potential as an inducer of vasculogenesis.

Gender-specific prognosis and risk impact of C-reactive protein, hemoglobin and platelet in the development of coronary spasm

BACKGROUND

Scarce data are available on hemoglobin and platelet in relation to coronary artery spasm (CAS) development. We sought to determine the roles that high-sensitivity C-reactive protein (hs-CRP), hemoglobin and platelet play in CAS patients.

METHODS

Patients (337 women and 532 men) undergoing coronary angiography with or without CAS but without obstructive coronary artery disease were evaluated during a 12-year period.

RESULTS

Among women with high hemoglobin levels, the odds ratios (OR) from the lowest (<1 mg/l) to the highest tertiles (>3 mg/l) of hs-CRP were 1.21, 2.15, and 5.93 (p=0.009). In women with low hemoglobin levels, an elevated risk was found from the middle to the highest tertiles of hs-CRP (OR 0.59 to 3.85) (p=0.004). This relationship was not observed in men. In men, platelet count was the most significant risk factor for CAS (p=0.004). The highest likelihood of developing CAS was found among women with the highest hs-CRP tertile and low platelet counts (OR 8.77; 95% confidence interval [CI] 2.20-35.01) and among men with the highest hs-CRP tertile and high platelet counts (OR 4.58; 95% CI 0.48-43.97). Neither hemoglobin level nor platelet count was associated with frequent recurrent angina in both genders with CAS whereas death and myocardial infarction were rare.

CONCLUSIONS

There are positive interactions among hs-CRP, hemoglobin and platelet in women with this disease, but not in men. While hemoglobin is a modifier in CAS development in women, platelet count is an independent risk factor for men. Both women and men have good prognosis of CAS.

Students' view upon graduation: a survey of medical education in Taiwan

BACKGROUND

Improving the quality of medical education is a key goal of government policy in Taiwan. The aim of this study was to reflect the responses of medical education from the perspective of graduating medical students in Taiwan. This is the first survey study of medical education in Taiwan.

METHODS

Using the Medical School Graduation Questionnaire from the Association of American Medical Colleges (AAMC), we distributed 406 questionnaires to medical students of four medical schools in their last semester, and received 270 back (response rate, 66.5%). There were 11 medical schools in Taiwan. Most questions were assessed on a 5-point Likert scale.

RESULTS

Students identified genetics, biochemistry, and ethics as the three most important premedical subjects preparing them for medical education and gross anatomy, physiology, and pharmacology as the three most helpful basic science subjects preparing them for clinical clerkships and electives. Most Taiwanese students were satisfied with their learning experience in internal medicine. Only 55.9% of students were confident that they had acquired the clinical skills required to become a resident, and 70.7% were satisfied with the quality of their medical education.

CONCLUSION

The study offers preliminary results on the views of graduating students on the medical education system in Taiwan. In particular, our government and medical educators need to continuously put more effort into building students' confidence in their clinical skills.

An endoluminal aortic prosthesis infection presenting as pneumoaorta and aortoduodenal fistula

Herein, we present a case of pneumoaorta and aortoduodenal fistula (ADF) caused by an endoluminal aortic prosthesis infection. An 82-year-old man underwent endovascular aneurysm repair with a stent graft to exclude a 5.1-cm abdominal aortic aneurysm. Three months after the index procedure, the patient was taken to the emergency department at a medical university hospital. He presented with a 2-d history of bloody diarrhea. An endoluminal aortic stent graft infection was diagnosed, and an ADF was identified. The patient died of septic shock despite emergency surgery and intensive care. When encountered, stent graft infections require appropriate antibiotics and graft explantation. The diagnosis of an ADF is important, and surgery remains the most effective management if septic shock presents despite conservative treatment.

Moderate to High Concentrations of High-Density Lipoprotein From Healthy Subjects Paradoxically Impair Human Endothelial Progenitor Cells and Related Angiogenesis by Activating Rho-Associated Kinase Pathways

Objective—

Recent clinical evidence has failed to demonstrate the benefits of elevation of serum high-density lipoprotein (HDL), suggesting potential loss of protective effects of HDL at high concentrations. This study aimed to investigate the concentration-related effects of HDL on in vitro and in vivo functions of human endothelial progenitor cells (EPCs) and related angiogenesis.

Methods and Results—

Early and late outgrowth EPCs were generated from human circulating mononuclear cells. Oxidized low-density lipoprotein reduced viability of late outgrowth EPCs, which was reversed dose dependently by HDL. In the absence of oxidized low-density lipoprotein, HDL at low concentrations (5–50 μg/mL, equal to 0.5–5 mg/dL in human) enhanced EPC tube formation by activating phosphatidylinositol-3 kinase/Akt/endothelial NO synthase pathways. Moderate to high concentrations (400–800 μg/mL) of HDL paradoxically enhanced EPC senescence and impaired tube formation by activating Rho-associated kinase (ROCK) and inhibiting phosphatidylinositol-3 kinase/Akt and p38 mitogen-activated protein kinase pathways. Rho-associated kinase inhibitors, either Y27632 or statins, prevented high HDL–induced EPC senescence and improved in vitro tube formation, as well as in vivo capacity of angiogenesis of EPCs.

Conclusion—

While protecting EPCs from the injury of oxidized low-density lipoprotein, moderate to high concentrations of HDL paradoxically impaired EPCs and related angiogenesis in the absence of oxidized low-density lipoprotein by activating Rho-associated kinase pathways, providing mechanistic evidence of potential hazard effects of HDL.

Reversible left ventricular apical ballooning associated with jet lag in a Taiwanese woman: A case report

Reversible left ventricular apical ballooning, without coronary artery stenosis, is a novel heart syndrome mimicking acute myocardial infarction, and is very rare in Taiwan. A 74-year-old Taiwanese woman returned from travelling abroad for one week and suffered from persistent, severe jet lag with sleep disturbance. She had a cold exacerbated by bronchial asthma for three days. She presented with sudden onset of chest pain after drinking three cups of coffee and taking a sauna for more than 1 h. On admission, an electrocardiogram showed ST segment elevation in leads II, III, aVF and V(3-6), and cardiac enzyme tests revealed minimal elevation. An echocardiogram showed apical ballooning and basal hyperkinesias of the left ventricle (LV) in systole. A coronary angiogram on the second day was normal, while the ST segment was still elevated, and the patient continued to experience chest pain. A negative T wave developed three days later. The electrocardiogram abnormality and LV dysfunction resolved completely six months later. A takotsubo (ampulla) cardiomyopathy was diagnosed. The activated myocardial adrenergic nervous system, stimulated by acute and marked stress in this patient, with more adrenergic innervations distributed in the apex of the LV, may be the trigger for this novel cardiac syndrome.

GroEL1, from Chlamydia pneumoniae, induces vascular adhesion molecule 1 expression by p37(AUF1) in endothelial cells and hypercholesterolemic rabbit

The expression of vascular adhesion molecule-1 (VCAM-1) by endothelial cells may play a major role in atherogenesis. The actual mechanisms of chlamydia pneumoniae (C. pneumoniae) relate to atherogenesis are unclear. We investigate the influence of VCAM-1 expression in the GroEL1 from C. pneumoniae-administered human coronary artery endothelial cells (HCAECs) and hypercholesterolemic rabbits. In this study, we constructed the recombinant GroEL1 from C. pneumoniae. The HCAECs/THP-1 adhesion assay, tube formation assay, western blotting, enzyme-linked immunosorbent assay, actinomycin D chase experiment, luciferase reporter assay, and immunohistochemical stainings were performed. The results show that GroEL1 increased both VCAM-1expression and THP-1 cell adhesives, and impaired tube-formation capacity in the HCAECs. GroEL1 significantly increased the VCAM-1 mRNA stability and cytosolic AU-binding factor 1 (AUF1) level. Overexpression of the p37^AUF1 significantly increased VCAM-1 gene expression in GroEL1-induced bovine aortic endothelial cells (BAECs). GroEL1 prolonged the stability of VCAM-1 mRNA by increasing both p37^AUF1 and the regulation of the 5′ untranslated region (UTR) of the VCAM-1 mRNA in BAECs. In hypercholesterolemic rabbits, GroEL1 administration enhanced fatty-streak and macrophage infiltration in atherosclerotic lesions, which may be mediated by elevated VCAM-1 expression. In conclusion, GroEL1 induces VCAM-1 expression by p37^AUF1 in endothelial cells and enhances atherogenesis in hypercholesterolemic rabbits.

Effect of sildenafil on ventricular arrhythmias in post-infarcted rat hearts

We have demonstrated that activation of ATP-sensitive potassium (K(ATP)) channels can attenuate sympathetic hyperinnervation. Sildenafil, a phosphodiesterase-5 inhibitor, has been shown to provide a preconditioning-like cardioprotective effect via opening of K(ATP) channels. The aim of this study was to investigate whether chronic administration of sildenafil attenuates cardiac sympathetic hyperinnervation after myocardial infarction through activation of K(ATP) channels and to compare it with the nitric oxide donor isosorbide dinitrate. Male Wistar infarcted rats induced by ligation of the anterior descending artery were randomized to either vehicle, nicorandil, sildenafil, isosorbide dinitrate, glibenclamide, or a combination of nicorandil and glibenclamide, or sildenafil and glibenclamide. Myocardial norepinephrine levels revealed a significant elevation in vehicle-treated rats compared with sham-operated rats, consistent with sympathetic hyperinnervation after infarction assessed by immunohistochemical analysis for tyrosine hydroxylase, growth associated factor 43 and neurofilament and by protein expression and mRNA of nerve growth factor. Sympathetic hyperinnervation was reduced after administering either nicorandil or sildenafil. Arrhythmic scores during programmed stimulation in the sildenafil-treated rats were significantly lower than those treated with the vehicle. Furthermore, the beneficial effects of sildenafil-induced were reversed by the addition of either glibenclamide or 5-hydroxydecanoate, implicating mitochondrial K(ATP) channels as the relevant target. Isosorbide dinitrate failed to confer similar antiarrhythmia. 1H-[1,2,4]oxadiazolo[4,3-α]quinoxalin-1-one, a soluble guanylyl cyclase inhibitor, did not influence the effect of sildenafil on the nerve growth factor. These data indicate that sildenafil after infarction attenuated sympathetic hyperinnervation and arrhythmias by activation of mitochondrial K(ATP) channels through a guanylyl cyclase-cGMP-independent pathway.

Extracorporeal membrane oxygenation-assisted primary percutaneous coronary intervention may improve survival of patients with acute myocardial infarction complicated by profound cardiogenic shock

PURPOSE

The aim of this study was to evaluate the impact of extracorporeal membrane oxygenation (ECMO) assistance on the clinical outcome of patients with acute myocardial infarction (AMI) that is complicated by profound cardiogenic shock (CS) who received primary percutaneous coronary intervention (PCI).

MATERIALS AND METHODS

We collected patients from January 2004 through December 2006 (stage 1); 25 patients who presented with AMI and received primary PCI and had profound CS were enrolled in the study. Intraaortic balloon counterpulsation (IABP) was the only modality for extracorporeal support in our hospital. From January 2007 through December 2009 (stage 2), 33 patients who presented with AMI and received primary PCI and had profound CS were enrolled; for this stage; both intra-aortic balloon counter-pulsation and ECMO support were available in our facility.

RESULTS

A Kaplan-Meier survival analysis displayed significantly improved survival for patients in stage 2 (P = .001; 1-year survival in stage 1 vs 2; 24% vs 63.64%). Patients presenting with either STEMI (ST segment elevation myocardial infarction) or NSTEMI (Non-ST segment elevation myocardial infarction) benefited from ECMO-assisted PCI (P < .05). In stage 1, patients with refractory ventricular tachycardia/ventricular fibrillation had a very low survival rate; however, in stage 2, the survival rate of patients with and without refractory ventricular tachycardia/ventricular fibrillation was similar (P = .316).

CONCLUSION

Extracorporeal membrane oxygenation-assisted PCI for patients with AMI that is complicated by profound CS may improve the 30-day and 1-year survival rates.

Reversible ischemia on treadmill exercise in left main coronary artery vasospasm

Coronary vasospasm of the left main coronary artery (LMCA) is a rare condition with potentially devastating consequences. We present 2 patients with LMCA vasospasm-related angina, the first being a 46-year-old woman and the second a 51-year-old woman. Both of them developed ST-segment ischemic changes on treadmill exercise tests. Coronary angiography showed spontaneous LMCA vasospasm in one patient and methylergonovine-induced LMCA vasospasm in the other patient. Follow-up treadmill exercise tests revealed no exercise-induced ischemia after calcium antagonist monotherapy. These cases demonstrate the importance of identifying LMCA vasospasm, as the treatment of choice varies in patients with angina pectoris. Reversible myocardial ischemia caused by LMCA vasospastic angina can be controlled by calcium antagonist monotherapy and detected by repeat non-invasive stress testing.

Magnetic resonance venography evaluating veins flow for legs by application of long stretch elastic bandage

AIM

Varicose veins are a common feature of chronic venous disease that causes pain and swelling of legs. Long stretch elastic bandages are one of the methods used to prevent and treat venous disease, but diagnostic benefit by magnetic resonance imaging (MRI) is not widely promoted. This study aims to evaluate the effects of long stretch elastic bandages using a non-contrast magnetic resonance venographic (MRV) technique by detecting influence on circumferences and flow velocities of varicose and deep veins, before and immediately after application of long stretch elastic bandages.

METHODS

Twelve patients presenting with visible varicose veins underwent MRV. The level of the superficial varicose and deep veins before and after wearing long stretch elastic bandages was recorded.

RESULTS

By comparing before and after long stretch elastic bandages, all 12 cases showed statistical significant decrease of the superficial venous flow areas; 9 out of 12 cases showed statistical significant change of the superficial (decreased) and deep (increased) venous flow rates. However, due to technical limitation, over half of the cases could not record the change of the deep venous flow areas.

CONCLUSION

The non-contrast MRV technique with Cine phase contrast, is capable to detect the short term beneficial effects of long stretch elastic bandages by measuring change of the superficial venous flow areas and superficial and deep venous flow rates.

Traditional Chinese medicine, Xue-Fu-Zhu-Yu decoction, potentiates tissue plasminogen activator against thromboembolic stroke in rats

AIM OF THIS STUDY

The Xue-Fu-Zhu-Yu decoction (XFZYD) is a well-known traditional Chinese medicine for treating cardiovascular diseases. The therapeutic effects of this XFZYD have been well documented especially in treating of atherosclerosis and hyperlipidemia. Since this decoction can induce endothelial progenitor cell angiogenesis, it can provide experimental evidence for the treatment of ischemic diseases. Patients who are admitted to the hospital with acute ischemic stroke are initially considered candidates for the recombinant tissue plasminogen activator (rt-PA). However, rt-PA therapy is still lesser than ideal due to its major side effect of hemorrhaging. Therefore, medical research has been devoted to finding an alternative and/or complementary therapy for ischemic stroke. In the present study, we evaluated the protective effect of the combination of XFZYD with or without rt-PA in a rat model of thromboembolic stroke.

MATERIALS AND METHODS

A cerebral thromboembolic stroke animal model and immunoblotting analysis were used to assess the effects of XFZYD and rt-PA.

RESULTS

Treatment with rt-PA (8 mg/kg) or XFZYD (1.5 and 3.0 g/kg/day) alone showed slight reductions in the infarct volume compared to solvent-treated rats. However, XFZYD (1.5 and 3.0 g/kg/day) obviously potentiated rt-PA-mediated reduction in the infarct volume in cerebral ischemic regions. In addition, treatment with rt-PA significantly reduced both tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS) but not hypoxia-inducible factor (HIF)-1 α or active caspase-3 expressions in ischemic regions, whereas treatment with XFZYD (3.0 g/kg/day) significantly reduced all of these protein expressions in ischemic regions. Moreover, treatment with XFZYD (1.5 and 3.0 g/kg/day) obviously potentiated rt-PA-mediated reductions in TNF-α, iNOS, HIF-1 α, and active caspase-3 expressions.

CONCLUSIONS

Results of this study suggest that XFZYD potentiated rt-PA-mediated neuroprotection against thromboembolic stroke in rats. This neuroprotection is probably mediated by the inhibition of HIF-1 α and TNF-α, followed by the inhibition of inflammatory responses (i.e., iNOS) and apoptosis (active caspase-3). These results provide a better understanding of the scientific validation of the therapeutic value of the combination of XFZYD with rt-PA in ischemic stroke.

Ursolic acid induces allograft inflammatory factor-1 expression via a nitric oxide-related mechanism and increases neovascularization

Ursolic acid (UA), a triterpenoid compound found in plants, is used in the human diet and in medicinal herbs and possesses a wide range of biological benefits including antioxidative, anti-inflammatory, and anticarcinogenic effects. Endothelial expression of allograft inflammatory factor-1 (AIF-1) mediates vasculogenesis, and nitric oxide (NO) produced by endothelial NO (eNOS) represents a mechanism of vascular protection. It is unclear whether UA affects the neovascularization mediated by AIF-1 and eNOS expression. This study investigated the effects and mechanisms of UA on angiogenesis in vivo in hind limb ischemic animal models and in vitro in human coronary artery endothelial cells (HCECs). This study explored the impact of UA on endothelial cell (EC) activities in vitro in HCECs, vascular neovasculogenesis in vivo in a mouse hind limb ischemia model, and the possible role of AIF-1 in vasculogenesis. The results demonstrate that UA enhances collateral blood flow recovery through induction of neovascularization in a hind limb ischemia mouse model. In vitro data showed that UA increases tube formation and migration capacities in human endothelial cells, and exposing HCECs to UA increased AIF-1 expression through a NO-related mechanism. Moreover, UA administration increased capillary density and eNOS and AIF-1 expression in ischemic muscle. These findings suggest that UA may be a potential therapeutic agent in the induction of neovascularization and provide a novel mechanistic insight into the potential effects of UA on ischemic vascular diseases.

Granulocyte colony-stimulating factor increases sympathetic reinnervation and the arrhythmogenic response to programmed electrical stimulation after myocardial infarction in rats

Granulocyte colony-stimulating factor (G-CSF) has been used for the repair of infarcted myocardium, but concerns have been raised regarding its proarrhythmic potential. We analyzed the influence of G-CSF treatment on sympathetic nerve remodeling and the expression of nestin in a rat model of experimental myocardial infarction (MI). Twenty-four hours after ligation of the anterior descending artery, male Wistar rats were randomized to receive either saline (MI/C) or G-CSF (MI/G) for 5 days. At 56 days after infarction, MI/G rats had a significantly higher left ventricular ejection fraction accompanied by a significant decrease in the left ventricular end-diastolic dimension than the MI/C group. Myocardial norepinephrine levels revealed a significant elevation in MI/G rats in the border zone compared with MI/C rats. Immunohistochemical analysis for tyrosine hydroxylase, growth-associated protein 43, and neurofilament also confirmed the changes of myocardial norepinephrine. At 5 days after infarction, MI/G rats had increased numbers of tissue-infiltrated CD34(+) cells, although a similar increase in circulating neutrophil counts between sham-operated rats treated with G-CSF and MI/G rats was observed. Compared with MI/C rats, MI/G rats showed an increase of nestin and nerve growth factor expression, as assessed by protein expression and mRNA levels. The arrhythmia scores during programmed stimulation were significantly higher in MI/G rats than in MI/C rats, suggesting proarrhythmic potential. These findings suggest that, although G-CSF administration after infarction improved myocardial function, it resulted in the activation of nestin and nerve growth factor expression and increased sympathetic reinnervation, which may increase the arrhythmogenic response to programmed electrical stimulation.