CREB-binding protein and HIF-1α/ß-catenin to upregulate miR-322 and alleviate myocardial ischemia-reperfusion injury.

Myocardial ischemia/reperfusion injury (MIRI) is a prevalent condition associated with numerous critical clinical conditions. miR-322 has been implicated in MIRI through poorly understood mechanisms. Our preliminary analysis indicated potential interaction of CREB-binding protein (CBP), a transcriptional coactivator and acetyltransferase, with HIF-1α/ß-catenin, which might regulate miR-322 expression. We, therefore, hypothesized that CBP/HIF-1α/ß-catenin/miR-322 axis might play a role in MIRI. Rat cardiomyocytes subjected to oxygen-glucose deprivation /reperfusion (OGD/R) and Langendorff perfused heart model were used to model MIRI in vitro and in vivo, respectively. We used various techniques such as CCK-8 assay, transferase dUTP nick end labeling staining, western blotting, RT-qPCR, chromatin immunoprecipitation (ChIP), dual-luciferase assay, co-immunoprecipitation (Co-IP), hematoxylin and eosin staining, and TTC staining to assess cell viability, apoptosis, and the levels of CBP, HIF-1α, ß-catenin, miR-322, and acetylation. Our results indicate that OGD/R in cardiomyocytes decreased CBP/HIF-1α/ß-catenin/miR-322 expression, increased cell apoptosis and cytokines, and reduced cell viability. However, overexpression of CBP or miR-322 suppressed OGD/R-induced cell injury, while knockdown of HIF-1α/ß-catenin further exacerbated the damage. HIF-1α/ß-catenin bound to miR-322 promoter to promote its expression, while CBP acetylated HIF-1α/ß-catenin for stabilization. Overexpression of CBP attenuated MIRI in rats by acetylating HIF-1α/ß-catenin to stabilize their expression, resulting in stronger binding of HIF-1α/ß-catenin with the miR-322 promoter and subsequent increased miR-322 levels. Therefore, activating CBP/HIF-1α/ß-catenin/miR-322 signaling may be a potential approach to treat MIRI.

Mammalian target of rapamycin inhibition attenuates myocardial ischaemia-reperfusion injury in hypertrophic heart.

Pathological cardiac hypertrophy aggravated myocardial infarction and is causally related to autophagy dysfunction and increased oxidative stress. Rapamycin is an inhibitor of serine/threonine kinase mammalian target of rapamycin (mTOR) involved in the regulation of autophagy as well as oxidative/nitrative stress. Here, we demonstrated that rapamycin ameliorates myocardial ischaemia reperfusion injury by rescuing the defective cytoprotective mechanisms in hypertrophic heart. Our results showed that chronic rapamycin treatment markedly reduced the phosphorylated mTOR and ribosomal protein S6 expression, but not Akt in both normal and aortic-banded mice. Moreover, chronic rapamycin treatment significantly mitigated TAC-induced autophagy dysfunction demonstrated by prompted Beclin-1 activation, elevated LC3-II/LC3-I ratio and increased autophagosome abundance. Most importantly, we found that MI/R-induced myocardial injury was markedly reduced by rapamycin treatment manifested by the inhibition of myocardial apoptosis, the reduction of myocardial infarct size and the improvement of cardiac function in hypertrophic heart. Mechanically, rapamycin reduced the MI/R-induced iNOS/gp91phox protein expression and decreased the generation of NO and superoxide, as well as the cytotoxic peroxynitrite. Moreover, rapamycin significantly mitigated MI/R-induced endoplasmic reticulum stress and mitochondrial impairment demonstrated by reduced Caspase-12 activity, inhibited CHOP activation, decreased cytoplasmic Cyto-C release and preserved intact mitochondria. In addition, inhibition of mTOR also enhanced the phosphorylated ERK and eNOS, and inactivated GSK3ß, a pivotal downstream target of Akt and ERK signallings. Taken together, these results suggest that mTOR signalling protects against MI/R injury through autophagy induction and ERK-mediated antioxidative and anti-nitrative stress in mice with hypertrophic myocardium.

Hypertrophied myocardium is vulnerable to ischemia/reperfusion injury and refractory to rapamycin-induced protection due to increased oxidative/nitrative stress.

Left ventricular hypertrophy (LVH) is causally related to increased morbidity and mortality following acute myocardial infarction (AMI) via still unknown mechanisms. Although rapamycin exerts cardioprotective effects against myocardial ischemia/reperfusion (MI/R) injury in normal animals, whether rapamycin-elicited cardioprotection is altered in the presence of LVH has yet to be determined. Pressure overload induced cardiac hypertrophied mice and sham-operated controls were exposed to AMI by coronary artery ligation, and treated with vehicle or rapamycin 10 min before reperfusion. Rapamycin produced marked cardioprotection in normal control mice, whereas pressure overload induced cardiac hypertrophied mice manifested enhanced myocardial injury, and was refractory to rapamycin-elicited cardioprotection evidenced by augmented infarct size, aggravated cardiomyocyte apoptosis, and worsening cardiac function. Rapamycin alleviated MI/R injury via ERK-dependent antioxidative pathways in normal mice, whereas cardiac hypertrophied mice manifested markedly exacerbated oxidative/nitrative stress after MI/R evidenced by the increased iNOS/gp91phox expression, superoxide production, total NO metabolites, and nitrotyrosine content. Moreover, scavenging superoxide or peroxynitrite by selective gp91phox assembly inhibitor gp91ds-tat or ONOO- scavenger EUK134 markedly ameliorated MI/R injury, as shown by reduced myocardial oxidative/nitrative stress, alleviated myocardial infarction, hindered cardiomyocyte apoptosis, and improved cardiac function in aortic-banded mice. However, no additional cardioprotective effects were achieved when we combined rapamycin and gp91ds-tat or EUK134 in ischemic/reperfused hearts with or without LVH. These results suggest that cardiac hypertrophy attenuated rapamycin-induced cardioprotection by increasing oxidative/nitrative stress and scavenging superoxide/peroxynitrite protects the hypertrophied heart from MI/R.

Hypercholesterolemia Abrogates Remote Ischemic Preconditioning-Induced Cardioprotection: Role of Reperfusion Injury Salvage Kinase Signals.

Remote ischemic preconditioning (RIPC) is one of the most powerful intrinsic cardioprotective strategies discovered so far and experimental data indicate that comorbidity may interfere with the protection by RIPC. Therefore, we investigate whether RIPC-induced cardioprotection was intact in hypercholesterolemic rat hearts exposed to ischemia reperfusion in vivo. Normal or hypercholesterolemic rat hearts were exposed to 30 min of ischemia and 2 h of reperfusion, with or without RIPC, PI3K inhibitor wortmannin, MEK-ERK1/2 inhibitor PD98059, GSK3ß inhibitor SB216763. Infarct size, apoptosis, MG53, PI3K-p85, p-Akt, p-ERK1/2, p-GSK3ß, and cleaved Caspase-3 were determined. RIPC reduced infarct size, limited cardiomyocyte apoptosis following IR that was blocked by wortmannin but not PD98059. RIPC triggered unique cardioprotective signaling including MG53, phosphorylation of Akt, and glycogen synthase kinase-3ß (GSK3ß) in concert with reduced proapoptotic active caspase-3. In contrast, RIPC failed to reduce myocardial necrosis and apoptosis as well as to increase the phosphorylated Akt and GSK3ß in hypercholestorolemic myocardium. Importantly, we found that inhibition of GSK with SB216763 reduced myocardial infarct size in healthy and hypercholesterolemic hearts, but no additional cardioprotective effect was achieved when combined with RIPC. Our results suggest that acute GSK3ß inhibition may provide a novel therapeutic strategy for hypercholesterolemic patients during acute myocardial infarction, whereas RIPC is less effective due to signaling events that adversely affect GSK3ß.

Alginate Oligosaccharide Prevents Acute Doxorubicin Cardiotoxicity by Suppressing Oxidative Stress and Endoplasmic Reticulum-Mediated Apoptosis.

Doxorubicin (DOX) is a highly potent chemotherapeutic agent, but its usage is limited by dose-dependent cardiotoxicity. DOX-induced cardiotoxicity involves increased oxidative stress and activated endoplasmic reticulum-mediated apoptosis. Alginate oligosaccharide (AOS) is a non-immunogenic, non-toxic and biodegradable polymer, with anti-oxidative, anti-inflammatory and anti-endoplasmic reticulum stress properties. The present study examined whether AOS pretreatment could protect against acute DOX cardiotoxicity, and the underlying mechanisms focused on oxidative stress and endoplasmic reticulum-mediated apoptosis. We found that AOS pretreatment markedly increased the survival rate of mice insulted with DOX, improved DOX-induced cardiac dysfunction and attenuated DOX-induced myocardial apoptosis. AOS pretreatment mitigated DOX-induced cardiac oxidative stress, as shown by the decreased expressions of gp91 (phox) and 4-hydroxynonenal (4-HNE). Moreover, AOS pretreatment significantly decreased the expression of Caspase-12, C/EBP homologous protein (CHOP) (markers for endoplasmic reticulum-mediated apoptosis) and Bax (a downstream molecule of CHOP), while up-regulating the expression of anti-apoptotic protein Bcl-2. Taken together, these findings identify AOS as a potent compound that prevents acute DOX cardiotoxicity, at least in part, by suppression of oxidative stress and endoplasmic reticulum-mediated apoptosis.

Second-generation versus first-generation drug-eluting stents in saphenous vein graftdisease: A meta-analysis of randomized controlled trials.

BACKGROUND: Second-generation drug-eluting stents (DESs) have become increasingly popular devices for patients with saphenous vein graft (SVG) disease. Second-generation DESs were designed to have more safety and efficacy than first-generation DES, but clinical outcomes in SVG disease remain conflicting. METHODS AND RESULTS: Randomized controlled trials (RCTs) were identified when comparing second- versus first-generation DESs in SVG disease. The main endpoint was all-cause death. The time of follow-up was at least 30days. The secondary endpoints were major adverse cardiovascular events (MACEs), target vessel revascularization (TVR), target lesion revascularization (TLR), myocardial infarction (MI), and stent thrombosis. These endpoints were assessed at 30days, 12months and 24months. Four RCTs with 1077 SVG patients undergoing the implantation of DES were collected in the current meta-analysis. As a result, second-generation DES-treated patients had the significantly lower MACE rates at 12months (P=0.03; OR: 0.69, 95% CI: 0.49,0.97). No differences in two groups were seen in all-cause death, MI, TVR, stent thrombosis and TLR. CONCLUSIONS: Our limited evidence indicated that, second-generation DES in SVG patients, compared with first-generation DES, offered similar levels of safety, but were more effective than the former one.

A three-pool model dissecting readily releasable pool replenishment at the calyx of held.

Although vesicle replenishment is critical in maintaining exo-endocytosis recycling, the underlying mechanisms are not well understood. Previous studies have shown that both rapid and slow endocytosis recycle into a very large recycling pool instead of within the readily releasable pool (RRP), and the time course of RRP replenishment is slowed down by more intense stimulation. This finding contradicts the calcium/calmodulin-dependence of RRP replenishment. Here we address this issue and report a three-pool model for RRP replenishment at a central synapse. Both rapid and slow endocytosis provide vesicles to a large reserve pool (RP) ~42.3 times the RRP size. When moving from the RP to the RRP, vesicles entered an intermediate pool (IP) ~2.7 times the RRP size with slow RP-IP kinetics and fast IP-RRP kinetics, which was responsible for the well-established slow and rapid components of RRP replenishment. Depletion of the IP caused the slower RRP replenishment observed after intense stimulation. These results establish, for the first time, a realistic cycling model with all parameters measured, revealing the contribution of each cycling step in synaptic transmission. The results call for modification of the current view of the vesicle recycling steps and their roles.

Influenza A (H1N1) pneumonia: an analysis of 63 cases by chest CT.

BACKGROUND: In early April 2009, cases of human infection with 2009 pandemic influenza A (H1N1) virus were identified in Mexico. The virus then spread rapidly to other regions of the world. From October 2009, sporadic imported cases of novel influenza A (H1N1) were continuously confirmed in Suzhou. The aim of the study was to review the chest CT findings in 63 patients with laboratory-confirmed novel swine-origin influenza A (H1N1) virus (S-OIV) infection. METHODS: Chest CT examinations were collected from 63 S-OIV infected patients during their hospital stay. Three experienced radiologists inspected images to qualitatively and quantitatively characterize S-OIV induced image changes. CT scores of lesion severity were calculated based on the percentage of affected area to determine severity of infectious lesions. Patients were divided into two groups based on the leukocyte counts. Lesion patterns, local distributions, and quantitative measures were investigated and compared between the two groups. RESULTS: Various degrees of bilateral multifocal lesions of ground-glass opacities were found with or without consolidations on the chest CT images. The lesions were both bronchocentric and centrilobular. Patients with elevated leukocyte counts had more extensive lesions, in terms of severity and affected area, than the patients with normal leukocyte counts. The lesion severity scores of patients in the elevated leukocyte group were significantly higher than those of the normal leukocyte group in terms of the entire lung area (P < 0.01), and upper (P < 0.05) and lower (P < 0.01) lobes as well. There were changes in the CT characteristics seen at follow-up as demonstrated by lesions absorption (P < 0.01), especially in the upper lobe of the lung (P < 0.01), but less so in the middle lobe/lingual and lower lobe of the lung (P > 0.05). CONCLUSIONS: The most common CT findings in S-OIV infection patients were bilateral multifocal distributed ground-glass opacities and consolidations. The lesions were located dominantly at bronchocentric and centrilobular areas. Lung lesions were more obviously absorbed in upper lobes between two examinations. The observations and analysis from this study provide information that may be useful in image understanding and patient management for future pandemic influenza.