tbuckley/cabot-search huggingface dataset:
Abstract 8711: Double Serine Phosphorylation of P47 <sup>Phox</sup> At 303-304 is Critical for Acute Tnfα-Induced Ros Production but Not for Mapk Activation in Endothelial Cells
Authors: Lei Teng, Jian-Mei Li
Journal: Circulation (2011)

p47 phox is a major regulatory subunit of Nox2 enzyme, which by generating superoxide plays important role in TNFα-induced endothelial dysfunction. The p47 phox has several serines clustered within the carboxyl terminus , and their phosphorylation has been reported to be critical in Nox2 activation and endothelial reactive oxygen species (ROS) production in response to stimulation. To understand the mechanisms of p47 phox phosphorylation in mediating acute TNFα redox-signaling, we replaced serines (303-4, 310, 315, 320, 328, 345, 348, 359, 370 and 379) to alanines and transfected mouse microvascular endothelial cells (SVEC4-10) with these constructs. Compared to vector controls, S303-4A (double mutation), S310A, S315A, S328A, S345A, S370A and S379A reduced significantly the TNFα (100 U/mL for 30 min)-induced ROS production (P&lt;0.05), whereas only S328A, S345A, S370A and S379A (but not S303-4A, S310A and S315A) inhibited TNFα-induced ERK1/2 phosphorylation. The different effects of S303-304A on TNFα-induced ROS production and TNFα signaling were further investigated using coronary microvascular endothelial cells isolated from p47 phox knockout mice. Compared to the cells transfected with a wild-type p47 phox cDNA, S303-4A mutation significantly inhibited (~51+2%) TNFα-induced ROS production, but showed no significant effect on TNFα-induced MAPK activation, p47 phox association with TRAF4, p47 phox binding to p22 phox and p47 phox membrane translocation. Knockdown of TRAF4 with siRNA abolished TNFα-induced ERK1/2 phosphorylation in S303-4A transfected p47 phox knockout cells. In conclusion, phosphorylation of p47 phox at different serines plays distinct roles in endothelial cell response to acute TNFα stimulation. Double serine phosphorylation (S303 and S304) of p47 phox is crucial in acute TNFα-induced ROS production, but not involved in TNFα-signaling through TRAF4 and MAPK in endothelial cells.
Abstract 19425: Stress Perfusion Cardiac Magnetic Resonance Predicts Risk of Cardiac Events in Patients with Established Coronary Artery Disease
Authors: Ravi Shah, Bobak Heydari, Otavio Coelho-Filho, Sanjeev Francis, Venkatesh Murthy, Michael Pencina, Siddique Abbasi, Henry Feng, Tomas Neilan, Ron Blankstein, Michael Steigner, Michael Jerosch-Herold, Raymond Kwong
Journal: Circulation (2012)

BACKGROUND: Current prognostic risk assessment has limited sensitivity for identification of patients at high risk for cardiac events with established CAD. We evaluated the prognostic value of stress cardiac magnetic resonance (CMR) imaging to reclassify risk in patients with established CAD. METHODS: We performed clinically indicated stress CMR imaging in 815 patients, with follow-up for cardiac death (CD) or acute myocardial infarction (AMI; primary outcome) over a median 1.9 years. Univariate and multivariate Cox regression models were used to determine clinical and imaging characteristics associated with risk. Annual event rates were calculated and stratified by presence and absence of prior CAD. Net reclassification improvement and ROC analysis were used for the addition of inducible ischemia by CMR beyond a best-overall clinical multivariate model of risk for discrimination and reclassification. RESULTS: Of the 815 patients referred for stress CMR, 13 failed to complete CMR (2%), and 97% had interpretable image quality. Inducible ischemia (ISCH) strongly independently predicted primary outcome in CAD patients (HR = 8.17, 95% CI 2.9-23.1, p = 0.0001). No ISCH was associated significantly improved event-free survival in patients with and without CAD (p&lt;0.001) and a &lt;1% annual rate of CD, with lower annual rates of CD/AMI in patients with and without CAD. ISCH improved risk discrimination over a best-overall clinical risk model (p&lt;0.0001). Addition of ISCH to the best-overall clinical model resulted in a net reclassification improvement of 0.229 (95% 0.063-0.391, p&lt;0.05). CONCLUSIONS: Inducible ischemia by stress CMR is a powerful, independent prognostic marker in patients with symptomatic, established CAD. A negative stress CMR is associated with a &lt;1% rate of CD, and reclassifies risk of future cardiac events in patients otherwise considered at moderate or high risk by clinical assessment.
Abstract 19466: Metabolomic and Gene Expression Changes in End-Stage Heart Failure are Reversed by Left Ventricular Assist Device
Authors: Anisha Gupte, Dale J Hamilton, Andrea M Cordero-Reyes, Keith A Youker, Matthias Loebe, Robert D Stevens, Brett Wenner, Olga Ilkayeva, Heinrich Taegtmeyer, Christopher B Newgard, Guillermo Torre-Amione, Willa A Hsueh
Journal: Circulation (2012)

Introduction: Heart muscle tissue in advanced heart failure (HF) is reported to be ‘energy-depleted’ and inflexible to metabolic changes. Left ventricular assist devices (LVAD) and ventricular unloading with LVAD is known to regress cardiac hypertrophy, reduce fibrosis and partially improve function. The metabolic alterations with HF and LVAD support are not fully understood. We hypothesize that HF is associated with metabolic changes that are reversible with LVAD placement. Methods: We analyzed gene and protein expression and performed metabolomics analyses in failing left ventricular (LV) tissue obtained at the time of heart explant or LVAD placement (HF, n = 13) and removal (post-LVAD, n = 7). Control LV tissue was procured from patients undergoing heart-lung transplantation for severe right HF (control, n = 4). P&lt;0.05 was considered significant. Results: In HF samples, expression levels of mitochondrial transcription factors and coactivators were decreased, while LVAD increased expression of PGC1α, PGC1β, ERRγ and TFAM to levels of control samples. Gene and protein expression of mitochondrial complex subunits NDUFS6, SDHA, UQCRC1, Cox5a, ATP5a1 were reduced in HF, but increased after LVAD. LVAD rescued reduced expression of fatty acid oxidation genes CPT2, ACADvl, ACADm, HADHA and PPARα, as well as pyruvate and glucose metabolism genes ME3, MCT1, PDHB, GPT and PFK. Targeted metabolomics analysis showed a reduction in short- and medium-chain acylcarnitines (C2-C10) in failing LV indicating decreased substrate catabolism, with these analytes universally restored to normal post-LVAD. Pyruvate levels tended to increase (P=0.07), whereas all measured Krebs cycle intermediates including citrate, α-ketoglutarate, succinate, fumarate and malate were reduced in the HF samples compared to normal controls. LVAD normalized pyruvate levels, and normalized the levels of all Krebs cycle intermediates. Conclusion: Both the gene expression and metabolomics profiles for mitochondrial, fatty acid, pyruvate and glucose metabolism pathways indicate that HF is associated with a global defect in substrate utilization. Complete reversal by ventricular unloading demonstrates the reversibility of metabolic defects.
Abstract 8958: The Role of Right Ventricular Dysfunction/Venous Congestion in Cardiac-Renal Interactions
Authors: Jeffrey M Testani, Melissa Chen, Brian McCauley, Richard Shannon, You-Tang Shen
Journal: Circulation (2011)

Introduction: It has been thought that the primary driver of renal dysfunction (RD) in heart failure (HF) is diminished renal perfusion secondary to reduced cardiac output. However, this relationship has not been confirmed in recent clinical studies. Rather, strong associations between RD and right ventricular (RV) dysfunction/venous congestion have been identified. Hypothesis: If RV dysfunction/venous congestion are causative of HF induced RD, the addition of RV dysfunction to a standard left ventricular (LV) HF model should produce incremental RD, independent of changes in cardiac output. Methods: Eleven swine were chronically instrumented with intravascular catheters, intra-cardiac pressure transducers, and vascular flow probes on the ascending aorta and renal artery. After 2 weeks of recovery, biventricular failure was induced by serial microembolization of the pulmonary vascular bed (2-3 mg/kg of 65 micron glass spheres, times 6 infusions) followed by ventricular pacing at 170 BPM (RV+LV group, n=7). The remaining 4 pigs served as a pacing only control (LV group). Measurements of cardiac and renal parameters were made in the conscious state at baseline and after 2 weeks of pacing. Results: Baseline renal and cardiac parameters were similar between groups. After 2 weeks of pacing, LV end diastolic pressure was increased and LV dP/dT and cardiac output were decreased (p&lt;0.05), however these parameters did not differ between groups (p≥ 0.19 for all). Notably, right atrial pressure was significantly higher (LV group=4.7 ± 1.3 vs. RV+LV group= 12.1 ± 1.1 mmHg, p=0.02) and renal blood flow was significantly lower in the RV+LV group (LV=144.0 ± 3.2 vs. RV+LV= 94.4 ± 16.0 ml/min, p=0.03) despite a similar mean cardiac output between groups (LV group=3.8 ± 0.3 vs. RV+LV group=4.0 ± 0.4 l/min, p=0.76). Conclusion: Despite a comparable degree of LV dysfunction and similar reductions in cardiac output, conscious swine with biventricular dysfunction had a disproportionate impairment in renal perfusion. These results provide mechanistic support for human observational studies linking RV dysfunction/venous congestion with RD.
Abstract 19432: Exit Site of Ischemic Ventricular Tachycardia: Lessons from Simultaneous Multi-Electrode Mapping Era Applied to Sequential Mapping Era
Authors: Stephane Masse, Eugene Downar, Elias Sevaptsidis, John Asta, Louise Harris, Douglas Cameron, Krishnakumar Nair, Vijay Chauhan, Dana Spears, Andrew Ha, Kumar Nanthakumar
Journal: Circulation (2012)

Background: Ventricular tachycardia mapping in the sequential era is dependent on determining the exit site using entrainment mapping and or activation mapping. During entrainment mapping, VT has the potential of degenerating into ventricular fibrillation, requiring cardioversion that may distort the electroanatomic map. In addition entrainment may change the activation sequences and initiate another VT. Thus it is of importance to identify the exit site based on temporal characteristics of the activation map and characterize the exit site. In the era of point by point sequential mapping it is unclear how much time ahead of surface activation is the activation at the exit site. We sought to determine the temporal characteristics of the exit site where successful ablation was performed in relation to the surface activation. Methods and Results: Twelve patients with ischemic VT who had multi-electrode simultaneous endocardial mapping during ventricular tachycardia were retrospectively reviewed. 16 VTs induced in these twelve patients were analyzed and the activation sequence in systole, diastole, and the presystolic period was annotated. Activation time in relation to surface activation was characterized at the exit site where ablation was performed. Mapping was performed with a custom-made system consisting of a 112 electrode endocardial array with simultaneous uni and bipolar recording. Filter settings for uni was 0.1 - 200 Hz, bipolar 28 - 700Hz, sampling rate was 1 kHz for uni and 2 kHz for bipolar electrograms.The mean activation time at the exit site was 60 +/- 24 msec ahead of surface VT activation. The range of the timing of the activation at the exit site preceding surface activation was was 18 - 114 ms. The unipolar characteristic at the site was not useful in identifying timing on a consistent basis. Conclusion: The exit site of an ischemic ventricular tachycardia is on average 60 ms ahead of surface activation. This presytolic timing is earlier than what is generally believed in the current sequential mapping era of VT ablation. Our analysis suggests that catheter position at shorter activation times would indicate a location in the post exit site and unlikely to produce a useful outcome.
Abstract 19436: cAMP Regulation of Vascular Endothelial Ectoenzyme ENTPD1
Authors: Amy E Baek, Hui Liao, Scott H Visovatti
Journal: Circulation (2012)

Ectonucleoside triphosphate diphosphohydrolase 1 (or CD39), an enzyme expressed on the plasmalemma of leukocytes and endothelial cells, serves as a potent antithrombotic agent by sequentially phosphohydrolyzing ATP and ADP, to generate AMP. CD39 is thus able to locally deplete levels of extracellular ATP and ADP, which would otherwise promote inflammation and platelet aggregation by binding P2X and P2Y classes of purinergic receptors found on leukocytes and platelets. The only known pathway for the transcriptional regulation of CD39 was described in recent work by this lab, which demonstrated that increased cAMP levels led to CD39 upregulation in murine macrophages through binding to the cAMP response elements (CRE) in the CD39 promoter with a consequent increase in CD39 transcription. Here, in contrast, we show that human endothelial cells (from umbilical vein; HUVEC) express less CD39 in response to elevated cAMP levels. Furthermore, we demonstrate that blockade of a major cAMP effector protein, protein kinase A (PKA), restores CD39 expression. Treatment of HUVEC cells with 250 μM 8-Br-cAMP, a cell permeable analogue of cAMP, led to a 2-fold decrease in CD39 protein from whole cell lysates in Western blots (18 hrs, p&lt;0.001, n=5), and this pattern persisted in time course assays from 8 hours to 24 hours. This result was confirmed with immunoprecipitation for CD39 in HUVEC supernatants, where 8 hours of 8-Br-cAMP treatment at 250 μM led to a 2.2-fold decrease in CD39 protein. ELISA measurements of HUVEC treated with 20 μM of the PKA inhibitor H89 led to a 2.8-fold increase compared to control of CD39 protein from HUVEC supernatants (p=0.0021, n=6). This was confirmed by Western blot, where co-treatment with 250 μM 8-Br-cAMP and 20 μM H89 for 8 hours led to a 50% increase measured by Western blot in CD39 protein compared to control in whole cell lysates (p&lt;0.05, n=3). Together, these data demonstrate that endothelial expression of CD39, a potent antithrombotic and anti-inflammatory enzyme, is modulated by the cAMP/PKA pathway, and contributes to basic understanding of the regulatory pathways governing CD39.
Abstract 19599: Loss of Alpha-Catenins Increases Nuclear Yap and Cardiomyocyte Proliferation and Improves Cardiac Function Following Myocardial Infarction
Authors: Jifen Li, Erhe Gao, Steven Goossens, Frans van Roy, Glenn Radice
Journal: Circulation (2012)

Background: Shortly after birth, muscle cells of the mammalian heart lose their ability to divide. Thus, they are unable to effectively replace dying cells in the injured heart. The recent discovery that the transcriptional co-activator Yap is necessary and sufficient for cardiomyocyte proliferation has gained considerable attention. However, the upstream regulators that control Yap activity in the heart remain largely unknown. Objective: To investigate the role of α-catenins in the heart using cardiac-specific αE- and αT-catenin double knockout (α-cat DKO) mice. Methods: We used two cardiac-specific Cre transgenes to delete both αE-catenin (Ctnna1) and αT-catenin (Ctnna3) genes either in the perinatal or in the adult heart, and performed a series of experiments to examine the role of α-catenins under normal and pathological conditions. Results: Postnatal depletion of α-catenins caused a decrease in cardiomyocyte size and an increase in cardiomyocyte number in the α-cat DKO mice. Increased nuclear Yap and the cell cycle regulator cyclin D1 accompanied cardiomyocyte proliferation in the α-cat DKO hearts. In comparison, ablation of α-catenins in the adult heart did not result in a proliferative phenotype. However, inactivation of α-catenins improved cardiac function following myocardial infarction. Increased nuclear Yap along with increased number of cells in cytokinesis indicated that cardiomyocyte proliferation contributed, at least in part, to the improved contractile function in the α-cat DKO heart following injury. Conclusions: These studies demonstrate that α-catenins are critical regulators of Yap, a transcriptional co-activator essential for cardiomyocyte proliferation. Furthermore, we provide proof-of-concept that inhibiting α-catenins might be a useful strategy to promote myocardial regeneration following injury.
Abstract 19756: Association of Increased PTEN-Induced Putative Kinase 1 (PINK1) Expression and Oxidative Damage in Gastrocnemius Myofibers of Patients with Peripheral Arterial Disease
Authors: Panagiotis Koutakis, George P Casale, Dimitrios Miserlis, Jonathan R Thompson, Evlampia Papoutsi, Ha M Duy, Stanley A Swanson, Zhen Zhu, Iraklis I Pipinos
Journal: Circulation (2012)

Introduction: Oxidative damage (OxD) determined as protein adducts of 4-hydroxy-2-nonenal (HNE) is increased in gastrocnemius myofibers of patients with peripheral arterial disease (PAD) and correlates with disease progression. Mitochondria in PAD gastrocnemius exhibit structural damage and respiratory dysfunction; however, the extent of mitochondrial damage and its relationship to OxD have not been determined. PINK1 is a glycoprotein normally expressed in low abundance on the mitochondrial external membrane. Mitochondrial damage signaled as loss of ion potential across the external membrane produces a marked increase in PINK1, which initiates mitophagy. In this study, we tested the hypothesis that mitochondrial damage is 1) prevalent among gastrocnemius myofibers of PAD patients and 2) linked to OxD. Methods: Gastrocnemius biopsies were collected from five PAD patients with claudication and five controls matched on the basis of age, gender, smoking history and type II diabetes. Biopsy specimens were fixed in methacarn, embedded in paraffin, sectioned and mounted to glass slides. Fluorescence labeled PINK1 protein and HNE adducts in individual myofibers, were quantified by quantitative fluorescence microscopy and expressed as mean pixel intensity in gray scale units (gsu) corrected for background. Results: PINK1 protein expression was increased (p=0.008) in PAD (mean ± S.E.M.; 494.78 ± 0.02 gsu) compared to control myofibers (102.45 ± 0.02 gsu) of the gastrocnemius. PINK1 was increased in 93% of the PAD myofibers. The association of increased (greater than two standard deviations above the control means) PINK1 expression and HNE adducts was determined for PAD myofibers. HNE adducts were increased in 67% of a random sample of PAD fibers expressing increased PINK1. Conclusions: Increased expression of PINK1 protein in the gastrocnemius myofibers of PAD patients with claudication, has established the presence of irreversible mitochondrial damage in a large proportion of myofibers. Elevation of OxD in 67% of PAD myofibers expressing increased PINK1 links OxD and mitochondrial damage. The data are consistent with a contribution of OxD to myofibers in PAD gastrocnemius, by damaged mitochondria.
Abstract 8742: Deletion of CIKS (Act1 or traf3ip2) Abrogates Angiotensin-II-induced Cardiac Hypertrophy <i>in vitro</i> and <i>in vivo</i>
Authors: Prakashsrinivas Shanmugam, Anthony J Valente, Laurent Delafontaine, Jason D Gardner, Ulrich Siebenlist, Bysani Chandrasekar
Journal: Circulation (2011)

Chronic elevation of Angiotensin-II (Ang-II) can lead to cardiac hypertrophy and heart failure. Ang-II activates NF-κB and AP-1, and induces pro-inflammatory cytokines and pro-growth factors. The adapter molecule CIKS (connection to IKK and SAPK/JNK; also known as Act1 or traf3ip2) lies upstream of IKK and JNK, and mediates both autoimmune and inflammatory diseases. We hypothesized that CIKS plays a causal role in Ang-II-induced cardiac hypertrophy. The heart and body weights were similar in both wild type (WT; C57Bl/6) and CIKS null mice (C57Bl6 background). However, continuous infusion of Ang-II (1.5 μg/kg/min for 7 days; n=8/group) led to cardiac hypertrophy (heart wt/tibial length, 38% increase vs saline, P &lt;0.01) and upregulation of CIKS mRNA (2-fold, P &lt;0.05) and protein (3.1-fold, P &lt;0.01) in WT, but not CIKS null mice ( P &lt;0.001 vs WT+Ang-II). Ang-II increased heart rate and systolic blood pressure in both, but levels trended higher in the CIKS null (not significant). Ang-II increased NF-κB and AP-1 DNA binding activities, and induced ANP, cytokine (TNF-α, IL-18), growth factor (WISP1), and MMP (MMP-2, -9, and -14) expression/activity in WT, but not CIKS null mice. Ang-II treatment of adult cardiomyocytes from WT resulted in significant hypertrophy (increased cell surface area and protein without DNA synthesis; both at least P &lt;0.01), PI3K, Akt, p70 S6K and ribosomal S6 protein activation, and ANP, TNF-α, IL-18, WISP1, and MMPs expression. Moreover, Ang-II induced CIKS mRNA (at 1 h, 5.1-fold, P &lt;0.001) and protein (at 2 h, 3.78-fold, P &lt;0.01) in a time- and dose-dependent manner. Importantly, CIKS knockdown (lentiviral shRNA) blunted Ang-II induced IKKβ and JNK activities, p65 and c-Jun phosphorylation, and NF-κB and AP-1 DNA binding and reporter gene activities, cytokine, WISP1, and MMPs in WT-cardiomyocytes. These results were recapitulated in CIKS null cardiomyocytes. Our results demonstrate that CIKS plays a critical role in Ang-II-mediated cardiac hypertrophy in vivo and cardiomyocyte hypertrophy in vitro thorough induction of IKK/NF-κB and JNK/AP-1-dependent cytokine, growth factor, and MMP expression. CIKS is a potential therapeutic target in cardiac hypertrophy and congestive heart failure.
Abstract 9171: An Increase in Late Sodium Current Causes Junctional Tachycardia in Mice Expressing an LQT3 SCN5A Mutant Na <sup>+</sup> Channel
Authors: Lin Wu, Gongxin Liu, Bo Yang, Hong Li, Kirsten Hoyer, John C Shryock, Luiz Belardinelli
Journal: Circulation (2011)

Background: Junctional tachycardia (JT) is predominantly seen in young patients, where it is associated with significant morbidity and mortality and poor response to drug therapy. We documented JT in mice with the cardiac gain-of-function SCN5A mutation N1325S and its inhibition by ranolazine, suggesting that enhancement of the late Na + current (late I Na ) is a novel cause of JT. Methods: In N1325S mutant and wild type mice, an eight-channel surface ECG was recorded weekly for 15 weeks. Intracardiac electrograms from catheterization of intact animals and studies of isolated hearts were performed. Results: JT occurred in an age-dependent manner in N1325S mutant but not in wild type mice. The number of N1325S mice with JT increased from 0 % at 3 weeks or less of age to 13.7, 46.6, 79.3, 89.1 and 100 % at 4, 5, 7, 10 and 15 weeks of age, respectively, and heart rate (HR) increased from 520±22 bpm at 5 weeks to 598±14 bpm at 15 weeks (n=58, p&lt;0.01). In contrast, in littermate wild type mice HR was 463±12 bpm and sinus rhythm was maintained. HR was significantly higher at all ages in N1325S mice with JT than in wild type mice (n=45, p&lt;0.01). JT in N1325S mouse isolated hearts and in intact animals could not be terminated by programmed atrial stimulation (n=7), suggesting that reentry is unlikely to be the mechanism underlying the JT. In isolated hearts, the late I Na inhibitors ranolazine (1-30 µM, n=6), TTX (0.1-1 µM, n=8) and flecainide (0.1-1 µM, n=3) slowed the rate of the JT and converted JT to sinus rhythm in a concentration-dependent manner. Results from the intracardiac EP study confirmed the JT in N1325S mice, and the JT was terminated by intraperitoneal administration of ranolazine (15-30 mg/kg). Conclusion: The gain-of-function cardiac SCN5A mutation N1325S is associated with JT in mice. An enhanced late I Na is a novel mechanism for JT. Drugs that inhibit late I Na may be effective in treating JT in patients with enhanced late I Na .