bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 18632: Expression and Function of the Ryanodine Receptor Subtype 3 in Cardiac Purkinje Fibers: Potential Target for Selective Treatment of Purkinje Ectopy?
Authors: Daniels Rebecca E , Miller Lawson , Arora Simran , Chia Elizabeth , Miura Masahito , McGuire John , Stuyvers Bruno D
Published: April 2024

BACKGROUND:
Focal “discharges” from the Purkinje network were shown to trigger VTs and VFs in ischemic hearts. In dog model of myocardial infarction, this Purkinje ectopy was attributed to abnormal oscillations of Ca
2+
concentration in Purkinje cells (Pcells). The cause of these oscillations is unknown mostly because important features of Ca
2+
handling of normal Pcells remain obscure. It was proposed that distinct forms of Ca
2+
channels participate to Ca
2+
release from endoplasmic reticulum (ER) in canine Pcells, wherein RyR3 was found to co-exist with IP3R and RyR2. Nevertheless, presence of this system of multiple Ca
2+
channels has not been explored in other species and the function of this system in Pcells remains unclear. Here, we examined the hypothesis that a specific region of RyR3 Ca
2+
release exists in Pcells of large size hearts and forms anatomical and functional coupling between membrane and core ER-Ca
2+
releases.

METHODS:
Purkinje strands were dissected from hearts of 36 Yucatan swine. Enzymatically dispersed Pcells were loaded with Fluo4. Intracellular Ca
2+
dynamics was assessed by 2D confocal imaging (92cells). Function of ER-Ca
2+
channels was investigated through effects of selective inhibitors on intracellular Ca
2+
transients (65cells). mRNA level was measured in Purkinje fibers by RT-PCR for RyR isoforms 1,2,3 and IP3R (11 animals). Protein expression was characterized by immunofluorescence (34 cells).

RESULTS:
Compared to myocardium, 100fold larger RyR3 mRNA level was detected in Purkinje fibers. 3D distribution of RyR3-Ab revealed a concentric RyR3 layer at the cell periphery. Spark rate-pCarelations showed that Ca
2+
sensitivity of ER-Ca
2+
release at the Pcell periphery was 2fold larger than further in the core. 3 distinct velocities were detected in the typical centripetal Ca
2+
propagation of Pcells. RyR3 inhibitor dantrolene (10µM) immediately reduced the Ca
2+
release event rate by 50% in the periphery only.

CONCLUSION:
RyR3 is a major component of the specific Ca
2+
signaling of Pcells of large mammalian heart, suggesting that any RyR3 alteration may cause pro-arrhythmic Ca
2+
abnormalities in ischemic heart. Purkinje-specificity of RyR3 highlights a new target for selective treatment of Purkinje-originated dysrhythmia.
Abstract 18664: Left Ventricular End-Diastolic Pressure is a Predictor of Survival in Patients Undergoing Coronary Artery Bypass Graft Surgery with Left Ventricular Dysfunction
Authors: Nagendran Jeevan , Norris Colleen M , Appoo Jehangir , Ross David B , Nagendran Jayan
Published: April 2024

There is an association between depressed left ventricular ejection fraction (ejection fraction < 35%; LVEF) and increased mortality in patients undergoing coronary artery bypass graft (CABG). There are a few studies suggesting that elevated pre-operative left ventricular end-diastolic pressure (LVEDP) is an independent predictor of operative mortality for patients undergoing CABG, and could be a greater risk than LVEF < 35%. It is unclear if LVEDP is a better predictor of long-term survival than LVEF in patients undergoing CABG. We hypothesized that LVEDP may add further prognostic value than LVEF alone. We studied 6790 consecutive patients from 2004-2011 undergoing isolated CABG at our institution. Patients were divided into four groups based on LVEF and LVEDP: Group 1 (LVEF≥35%, LVEDP<18mmHg), Group 2 (LVEF<35%, LVEDP<18mmHg), Group 3 (LVEF≥35%, LVEDP≥18mmHg), and Group 4 (LVEF<35%, LVEDP≥18mmHg). The 4 groups had similar pre-operative characteristics of age, history of stoke, renal failure, peripheral vascular disease (PVD), hypertension, and hyperlipidemia. Patients with a low LVEF (Groups 2 and 4) had a higher incidence of chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), smoking and history of myocardial infarction (p<0.001). The Kaplan-Meier survival curves identified that the groups with preserved LVEF had improved long-term survival compared to groups with depressed LVEF (p<0.001). As well, there was no significant correlation between elevated LVEDP and decreased survival in patients with a preserved LVEF (Group 1 versus Group 3, p=0.84). However, in patients with depressed LVEF<35%, an elevated LVEDP was associated with worse long-term survival when compared to patients with an LVEDP<18mmHg (Group 2 versus Group 4, p<0.001). The independent predictors of death by Cox proportional hazards modeling were: LVEF<35%, advanced age, COPD, PVD, dialysis dependent renal failure, and CHF (p<0.001); while elevated LVEDP≥18mmHg was not significant. We conclude that elevated LVEDP≥18mmHg is not an independent risk factor for mortality in patients undergoing isolated CABG; however, in patients with depressed LVEF<35%, an elevated LVEDP further prognosticates a significant decrease in long-term survival.
Abstract 18683: Outcomes of Patients Presenting with Acute Type A Aortic Dissection in the Setting of Prior Cardiac Surgery: An Analysis from the International Registry of Acute Aortic Dissection
Authors: Teman Nicholas , Peterson Mark D , Russo Mark J , Ehrlich Marek P , Myrmel Truls , Upchurch Gilbert R , Greason Kevin , Fillinger Mark , Forteza Alberto , Deeb Michael G , Montgomery Daniel G , Eagle Kim A , Isselbacher Eric M , Nienaber Christoph A , Patel Himanshu J
Published: April 2024

Introduction: Prior cardiac surgery can complicate the clinical presentation, diagnosis, and management of patients with type A aortic dissection (TAAAD). This report from the International Registry of Acute Aortic Dissection (IRAD) examines this hypothesis.

Methods: 352 of 2289 TAAAD patients (15.4%) enrolled in IRAD had cardiac surgery prior to dissection, including coronary artery bypass grafting (CABG, 34.6%), aortic or mitral valve surgery (38.4%), aortic surgery (44.7%), and other cardiac surgery (18.1%).

Results: Comparative differences in baseline demographics, clinical presentation, and management time are shown in Table 1. Patients with prior cardiac surgery were more likely to undergo CABG (p=0.006) or mitral valve replacement (p=0.001) at the time of dissection repair. Total cardiopulmonary bypass time was higher in patients with prior cardiac surgery (p<0.001); no difference was seen in cardiac arrest time (p=0.113) or cerebral ischemia time (p=0.286). In-hospital mortality was significantly higher for patients with prior cardiac surgery (33.5% vs. 24.0%, p70 (RR1.58, 95% CI 1.25-1.99), and medical management of acute dissection (RR 4.79, 95% CI 3.62-6.34). Kaplan-Meier analysis is shown in Figure 1.

Conclusion: Prior cardiac surgery not only delays presentation and diagnosis of acute type A dissections, but is also an important adverse risk factor for early and late mortality.
Abstract 18694: Connexin-43 Gene Variants are Associated with Risk of Ventricular Arrhythmias in Patients with a Depressed Ejection Fraction
Authors: Thakkar Happy , Piccini Jonathan P , Sun Albert Y , Haynes Carol , Grass Elizabeth , Nilsson Kent , Koontz Jason I , Hranitzky Patrick , Shah Svati H
Published: April 2024

Background:
Despite the life-saving benefits of implantable cardioverter defibrillator (ICD) therapy, only a minority of primary prevention patients ultimately receive ICD therapy for ventricular arrhythmias. Genetic risk factors may improve current risk stratification models. Connexin-43 is the predominant component of gap junctions in ventricular myocardium. Accordingly, we hypothesized that common genetic variants in connexin-43 are associated with risk of ventricular arrhythmias in patients with reduced ejection fraction.

Methods:
Caucasian individuals with an impaired ejection fraction (< 35%) who had received a primary prevention ICD were identified from the Duke Electrophysiology Genetic Studies (EPGEN) database (N=252). Six connexin-43 single-nucleotide polymorphisms (SNPs) were genotyped using Taqman. Association with ventricular arrhythmia, defined as an appropriate ICD shock or anti-tachycardia pacing for ventricular tachycardia or fibrillation, was tested using univariate and multivariable logistic regression models adjusted for sex, age, hypertension, hyperlipidemia, smoking, diabetes and coronary artery disease status.

Results:
Over a mean follow-up of 2.3 years, there were 42 cases of ventricular arrhythmia. In univariate analyses, two SNPs in complete linkage disequilibrium, rs11961755 and rs10456940, were associated with risk of ventricular arrhythmia (19% of cases vs. 44% of controls carried at least one copy of the minor allele, p=0.003 in the dominant genetic model). In multivariable models, these SNPs were associated with an odds ratio for ventricular arrhythmia of 0.27 (95% confidence interval 0.11-0.62, p=0.002). These relationships were not observed in African-American subjects (N=124). No other connexin-43 SNPs were associated with events.

Conclusions:
Genetic variants in connexin-43 are independently associated with risk of ventricular arrhythmia in patients referred for primary prevention ICDs. Prospective studies should address whether these novel markers improve risk stratification.
Abstract 18700: Accelerated Endothelial Regeneration and Survival Attenuate Vein Graft Atherosclerosis via Terahydrobiopterin-Dependent eNOS Coupling
Authors: Ali Ziad A , Rinze Ruth , Antoniades Charalambos , Douglas Gillian , Hu Yanhua , Xiao Qingzhong , Greaves David , Alp Nicholas , Xu Qingbo , Channon Keith
Published: April 2024

As a result of surgical trauma, ischemia and exposure to arterial pressure the majority of endothelium in vein grafts (VG) undergo necrosis or apoptosis. We hypothesized that increased eNOS coupling could protect endothelial viability after VG surgery. To investigate this we utilized a transgenic mouse with endothelial-targeted overexpression of the essential eNOS coupling cofactor BH4. We investigated the effect of BH4 on endothelial cell survival and vascular remodeling in vitro and in vivo using ApoE-KO mice with endothelial-targeted overexpression of the rate limiting enzyme of BH4 synthesis GTP cyclohydrolase 1 (GCH) and LacZ reporter gene. BH4 levels were increased 10-fold in primary endothelium and 5-fold in aorta from GCH/ApoE-KO mice compared with ApoE-KO, without concomitant increases in eNOS protein. Despite no differences at baseline, following 4 days of culture, total endothelial cell number, colony size and number from GCH/ApoE-KO mice were increased (5-fold P=0.05; 2-fold P=0.02; 2-fold P=0.06 respectively, n=6) as were putative EPC levels from bone-marrow mononuclear cells determined by culture (15%,P=0.04) and FACS (26%, P=0.03). Vascular injury as a result of VG surgery in ApoE-KO mice led to significant neointima that was augmented by 61% (P=0.002) in GCH/ApoE-KO mice. Furthermore, endothelial repopulation was accelerated by 21% (P=0.01) and endothelial survival 44% (P=0.03) in these animals. O2- production was significantly attenuated in GCH/ApoE-KO mice measured on both aortic sections using oxidative microtopography and whole aorta by lucigenin chemiluminescence. eNOS inhibition by L-NAME reversed these effects indicating that under basal conditions GCH/ApoE-KO mice had preserved eNOS coupling promoting NO synthesis. In keeping with these findings in 219 patients with coronary artery disease, analysis of saphenous vein and internal mammary artery identified that high vascular BH4 levels were associated with greater vasorelaxations to acetylcholine (P<0.05) and reduced total L-NAME inhibitable O2- suggesting improved eNOS coupling. Availability of BH4 within the endothelium critically modulates the response to vascular injury by maintaining eNOS coupling and accelerating endothelial regeneration.
Abstract 18707: Do Patients with Heart Failure and Atrial Fibrillation Adhere to Warfarin After Hospital Discharge? Findings from the Get With The Guidelines-Heart Failure Registry and Medicare Linked Database
Authors: Eapen Zubin , Mi Xiaojuan , Fonarow Gregg C , Heidenreich Paul A , Curtis Lesley H , Hernandez Adrian F , Al-Khatib Sana M
Published: April 2024

Background:
Prescribing warfarin at hospital discharge in patients with heart failure (HF) and atrial fibrillation (AF) without contraindications is recommended. Post-discharge adherence and long-term persistence to warfarin therapy among patients with HF and AF has not been fully described.

Methods:
We identified patients with HF and AF who were ≥65 years, without contraindications to warfarin therapy, and discharged home from hospitals in the GWTG-HF Registry from 1/2006-12/2009. We used linked Medicare prescription drug event data to measure adherence. Main outcome measures were prescription at discharge, outpatient prescription claim within 90 days, discontinuation, and adherence measured with the medication possession ratio. We used the cumulative incidence function to estimate rates of initiation and discontinuation.

Results:
Among 2691 eligible patients, 1856 (69.0%) were prescribed warfarin at discharge (Table). Within 90 days, 84.5% of eligible patients who had a discharge prescription filled a prescription for the therapy, compared with 12.3% of eligible patients without a discharge prescription (P<0.001). The median medication possession ratio over 1 year of follow-up was significantly higher among patients who were prescribed warfarin therapy at discharge (0.78 vs. 0.63) than among those not prescribed therapy (P<0.001). Among 1,631 patients who filled a prescription within 90 days of discharge, 7.1% discontinued therapy within 1 year.

Conclusions:
Approximately one-third of eligible patients with HF/AF and no reported contraindication to anticoagulation were not prescribed warfarin therapy at discharge from an HF hospitalization. Eligible patients without a discharge prescription seldom initiated therapy as outpatients. Most patients who were prescribed warfarin at discharge filled the prescription within 90 days and remained on therapy; yet even among these patients, opportunities to improve adherence remain. .
Abstract 18726: Single Cell Expression Profiling Reveals Up-Regulation of Radiation Sensitive Genes After Cardiac Computed Tomographic Angiography
Authors: Nguyen Patricia , Lee Won Hee , Hu Shijun , Sanchez-Freire Veronica , De Almeida Patricia , Narsinh Kazim , Lee Andrew , Fleischmann Dominik , Wu Joseph
Published: April 2024

Introduction:
High dose radiation activates radiation sensitive genes involved in the DNA damage response pathway, which is responsible for tumor suppression. Whether low dose radiation from medical imaging tests, such as cardiac computed tomographic angiography (CTA), changes the expression of these genes is unknown.

Hypothesis:
We hypothesize that low dose radiation alters the gene expression of 3 genes involved in tumor suppression: 1) MDM2 (a negative regulator of p53-induced cell cycle arrest and apoptosis), 2) BAX (a mediator of p53-induced apoptosis), and 3) DDB2 (a mediator of DNA repair).

Methods:
To determine the optimal time point for collection of blood in vivo, we performed an in vitro study. Blood from healthy volunteers (n=4) received either irradiation with a single dose of 25 mGy or 5,000 mGy, or received sham-irradiation. Whole blood was maintained at 37° for 6, 12, 24, and 38 hours following irradiation. Blood was collected from adult patients immediately before and 24 hours after CTA (n=10) or echocardiography (n=5). After separation of lymphocytes, gene expression was analyzed by single cell polymerase chain reaction.

Results:
The in vitro study showed significant up-regulation of MDM2, BAX, and DDB2 after low and high dose irradiation compared with sham-irradiated controls (Figure 1A, B, C). Similarly, up-regulation of these genes was noted in patients undergoing CTA (3-15 mSv) for various indications but not in patients undergoing echocardiography (Figure 1D). Of note, only 50% of patients had changes in gene expression.

Conclusions:
Low dose radiation from CTA alters the expression of genes involved in regulating tumor suppression. These findings, however, are seen in only 50% of patients. Further investigation is needed to determine how to identify these “radiosensitive” patients.
Abstract 18756: Association of Morphologic Variability with 6-Month Mortality in a General Cohort of Intensive Care Unit Patients: Results from the MIMICII Database
Authors: Chia Chih-Chun , Saeed Mohammed , Stultz Collin , Guttag John , Syed Zeeshan
Published: April 2024

Background:
Morphologic variability (MV) has been previously shown to identify patients at increased risk of mortality following acute coronary syndrome in retrospective analyses of randomized controlled clinical trial data. We assessed the relationship of MV and mortality in a general cohort of intensive care unit (ICU) patients.

Methods:
MV was calculated for ICU patients within the MIMICII database. Data from all ICU admissions with at least 10 hours of continuous ECG sampled at 9-bit quantization or greater during the first 24 hours were used (n=359). Patients were dichotomized into risk groups at the highest quartile. The primary endpoint was in-hospital or 6-month post-discharge mortality previously determined in MIMICII from the Social Security Death Index (n=83).

Results:
MV was associated with mortality on univariate analysis and in multivariate models adjusted for the Simplified Acute Physiology Score (SAPS) and the Sequential Organ Failure Assessment (SOFA) Score (Table). These results were consistent when the multivariate models were further adjusted for the Elixhauser comorbidity scores of cardiac arrhythmia and congestive heart failure (adjusted hazard ratio 2.46; 95% CI 1.30 - 4.66; p=0.005). The model constructed for the overall cohort using SAPS and SOFA showed improved discrimination and reclassification when MV was added (IDI 0.022, p=0.027; NRI 0.349, p=0.008).

Conclusions:
MV has value in risk stratification of the general cohort of ICU patients and provides complementary information to existing ICU scoring systems.
Abstract 18786: A Combined Risk Score for Predicting Incident Heart Failure
Authors: Sydow Karsten , Havulinna Aki S , Ojeda Francisco , Schnabel Renate B , Neumann Johannes T , Zeller Tanja , Jagodzinski Annika , Blankenberg Stefan , Salomaa Veikko
Published: April 2024

Introduction:
Identifying individuals at risk for incident heart failure may open the avenue for early preventive treatment. The aim of the study was to develop a straight-forward and clinically relevant risk score for predicting incident heart failure based on major clinical variables and biomarkers.

Methods:
Analyses were performed in 8,239 individuals of the population-based prospective FINRISK 1997 study, recruiting men and women aged 25-74 years. During the follow-up of 12 years, we identified 497 cases of incident heart failure. We considered major cardiovascular risk factors as clinical risk factor variables. We performed multivariate model selection via LASSO penalized Cox regression to obtain models predicting 6 and 12 years absolute risk of heart failure. The added value of the biomarkers NTproBNP, BNP, MR-proANP, MR-proADM, Cystatin C, hs Troponin I, MPO and CRP to the model was assessed by C-index and continuous net reclassification index (NRI).

Results:
Besides age, sex and study region (forced into the model), BMI and pulse pressure were selected for the 6 years heart failure risk model revealing an area under the curve of 0.82. Of all biomarkers tested, NTproBNP, MR-proANP, and BNP provided the strongest significant increase in C-index (0.87, 0.86, 0.85, respectively; p<0.001), followed by MR-proADM and Cystatin C (CI=0.84, p<0.001, p=0.004). Continuous NRIs for natriuretic peptides and MR-proADM were 30% - 35% (p<0.001), whereas Cystatin C showed a NRI of 10.1% (p=0.2). Inclusion of either hs Troponin I or CRP only slightly increased the predictive power of the model. Results for the 12 year model were similar, however, with attenuated NRIs, presumably due to the increased impact of age. MR-proADM was the only biomarker adding predictive information in models already including a natriuretic peptide.

Conclusions:
In a population based setting, age, sex, study region, BMI, and pulse pressure were the most powerful clinical variables for predicting incident heart failure. Biomarkers, i.e. natriuretic peptides and MR-proADM, significantly increased the predictive value of the basic model. These results will be validated within the European BiomarCaRE consortium to establish a biomarker supplemented European heart failure risk score.
Abstract 18796: Evaluation of Vasomera™, A Novel VPAC2-selective Vasoactive Intestinal Peptide Agonist, in Rats with Doxorubicin-Induced Cardiomyopathy: Evidence for Chronic Cardio-Protection
Authors: del Rio Carlos L , Youngblood Bradley , Yeh Steve T , Georgopoulos Lynne , Arnold Sue , Wallery Jeff , Hamlin Robert L
Published: April 2024

The natural vasoactive intestinal peptide (VIP) has been proposed as a therapeutic agent for heart failure via the activation of the G-protein-coupled VPAC1 and VPAC2 receptors; however, VIP's clinical utility is limited due to its short half-life and VPAC1-mediated side-effects. Vasomera™ is a novel long-acting biopolymer-based selective VPAC2-receptor agonist. Here, the chronic functional/geometrical effects of Vasomera when given daily to rats with doxorubicin-induced cardiomyopathy were evaluated. Sprague-Dawley rats were assigned to receive daily therapy with either Vasomera (9 mg/kg/day SQ; n = 15) or placebo (n = 10), and had heart failure induced via doxorubicin (DOXO, 3 mg/kg IP on M-W-F for 2 weeks; 18 mg/kg total); treatments started prior to HF induction (5 days) and continued until the end of the study. LV function/geometry were evaluated (via echo) prior to the start of dosing, as well as weekly during/after (for up to 3 weeks) HF induction. Animals were terminally studied to evaluate LV mechano-energetics. DOXO lead to marked LV dysfunction/remodeling, characterized by depressed systolic function (e.g., FS: -18 ± 4 %, P < 0.05), myocardial dilatation (e.g., LVIDd: +12 ± 2, P < 0.05), and wall-thinning (WT: -15 ± 5 %, P < 0.05). Vasomera therapy prevented DOXO-induced myocardial wasting/wall-thinning (WTs: +1 ± 4%, N.S.), ameliorating ventricular dysfunction (e.g., FS, -8 ± 2%, P < 0.05) and dilatation (LVIDd: +3 ± 3, N.S.). Vasomera treatment also tended to preserve the LV to body-weight ratio (-2.4 ± 2.0% vs. CTRL, N.S.), when compared to un-treated animals (-7.5 ± 3.0% vs. CTRL, P < 0.1). Terminally, Vasometra-treated animals tended (P < 0.1) to have lower LV filling pressures (EDP: 13 ± 1 vs. 9 ± 2 mmHg) and more-compliant ventricles (EDPVR: 2.9 ± 0.4 vs. 2.0 ± 0.3 mmHg/RVU). Daily treatment with Vasomera, a novel VPAC2 agonist, attenuated doxorubicin-induced myocardial remodeling/dysfunction in rats. In particular, Vasomera treatment prevented myocardial wall-thinning/muscular wasting. Moreover, acute Vasomera administration (IV) to rats with doxorubicin-induced cardiomyopathy, dose-dependently decreased myocardial loading and energetic demand, while improving LV systolic/diastolic function in a load-independent manner.
Abstract 18814: Autologous CD133+ Immunoselected Cells for the Treatment of "no-option" Critical Limb Ischemia: A Pilot Monocentric Study
Authors: Gnecchi Massimiliano , Arici Vittorio , Bozzani Antonio , Calliada Fabrizio , Cervio Elisabetta , Cervio Marila , Malpasso Giuseppe , Alessandrino Francesco , Del Fante Claudia , Viarengo Gianluca , Perotti Cesare
Published: April 2024

Background:
critical limb ischemia (CLI) is characterized by chronic ischemic rest pain, ulcers or gangren. CLI results in major amputation in about 50% of patients. Recently, it has been shown that bone marrow-derived (BM) CD34+/CD133+ circulating cells promote new vessel growth in experimental models of CLI. Accordingly, we investigated the feasibility and safety of local intramuscular administration of autologous immunoselected CD133+ (AI-CD133+) cells in “no-option” patients.

Methods:
the protocol was approved by the ethical committee of our hospital and 10 “no-option” patients suffering CLI were enrolled. BM-derived mononuclear cells were mobilized by G-CSF administration and collected by leukapheresis. CD133+ cells were selected with Clini-MACS (Miltenyi Biotec). AI-CD133+ cells were administered intramuscularly by direct injection. FACS analysis and Hill assay (CFU-Hill colonies) were performed both before and after G-CSF administration. Clinical examination, pain assessment, Ankle Brachial Index (ABI) and transcutaneous oxygen tension (TcPO2) measurements were performed before the treatment and 3, 6 and 12 months thereafter. At the same time points, patients underwent Contrast Enhanced UltraSound (CEUS) to assess muscle perfusion.

Results:
mobilization of CD34+/CD133+ cells was successful in 8 out of 10 patients. Of relevance, 6 out of 8 treated patients showed relevant clinical improvements. In particular, the treatment drastically ameliorated local pain and favored the healing of the ulcers (figure). The 2 non-responders, both diabetics, underwent major amputation. An overall increase in ABI rate was documented by CEUS (ABI at 12 months increased from 91,45 to 136,82; p<0.05). TcPO2 increased by 45.5±34.1% after 1 year (p<0.05). The number of CFU-Hill colonies was significantly lower (p<0.05) in CLI patients compared with healthy donors; after G-CSF stimulation, the number of CFU colonies significantly increased, except in those patients who did not respond to the treatment.

Conclusions:
our results demonstrate the feasibility and safety of G-CSF mobilized AI-CD133+ cell injection in end stage CLI patients. Clinical and instrumental data suggest a dramatic effect of CD133+ treatment, except in diabetic patients.
Abstract 18829: Inhibiting Bone Morphogenetic Protein Signaling Reduces Diabetes-Associated Non-Alcoholic Fatty Liver Disease Independent of Plasma Lipid Levels
Authors: Martyn Trejeeve , Shakartzi Hannah R , Mayeur Claire , Bloch Kenneth D , Malhotra Rajeev
Published: April 2024

Background:
Non-alcoholic fatty liver disease (NAFLD) is associated with diabetes and atherosclerotic heart disease and its presence predicts worse cardiovascular outcomes. However, the mechanisms responsible for NAFLD remain unclear and no targeted medical therapy exists. Given the essential role for bone morphogenetic protein (BMP) signaling in the development of atherosclerosis and related inflammation, we hypothesized that BMP signaling is upregulated in livers of diabetic mice (db/db) known to develop NAFLD and that pharmacologic inhibition of BMP signaling may reduce fatty liver disease.

Methods:
Livers from adult male wild-type (WT) and db/db mice were harvested to quantify Smad 1/5 phosphorylation and Id1 gene expression (markers of BMP signaling). Diabetic mice were treated with either vehicle or the small molecule BMP type I receptor inhibitor, LDN-193189 (LDN, 3 mg/kg twice daily IP), for 28 days. Plasma samples were collected, and livers were harvested for biochemical and histological examination. Hepatic fat content was estimated using colorimetric intensity quantification of hematoxylin & eosin stains.

Results:
Smad 1/5 phosphorylation and Id1 mRNA levels were 2.5- and 3.0-fold greater in livers of db/db mice than in WT mice (P=0.003 and 0.006, respectively; n=8 per group). Treatment of db/db mice with LDN decreased liver Smad 1/5 phosphorylation and Id1 mRNA levels associated with a 49% reduction in hepatic fat accumulation (P=0.017; see Figure). Furthermore, plasma alanine aminotransferase levels were less in LDN-treated mice than in vehicle-treated mice (mean ± SEM 194 ± 68 vs. 583 ± 153 U/L, n=7 per group, P=0.048); however, there was no difference in plasma cholesterol or triglyceride levels.

Conclusions:
Increased BMP signaling contributes to the development of NAFLD in a diabetic mouse model, independent of plasma lipid levels. Pharmacologic BMP inhibition may represent a novel therapy for NAFLD.
Abstract 18872: Krúppel-like Factor 6 Promotes Obesity and Glucose Intolerance Through Adipocyte Differentiation
Authors: Ishida Junichi , Suzuki Toru , Aizawa Kenichi , Sawaki Daigo , Matsumura Takayoshi , Friedman Scott L , Nagai Ryozo
Published: April 2024

Introduction:
Obesity and diabetes mellitus are regarded as major risk factors for cardiovascular disease. Recent studies suggest a potential role for some Krüppel-like zinc-finger transcription factors (KLFs) in adipogenesis. KLF6 is ubiquitously expressed and is also suggested to promote adipocyte differentiation
in vitro
. However, the metabolic roles of KLF6
in vivo
have yet to be addressed.

Hypothesis:
We assessed the hypothesis that KLF6 promotes obesity and pathogenesis of glucose intolerance through adipocyte differentiation.

Methods:
In the present study, we used heterozygote KLF6 knockout (KLF6
+/-
) mice and investigated whether KLF6 is involved in obesity
in vivo
.

Results:
On a normal diet, the body weight of KLF6
+/-
mice was similar to that of wild-type mice (28.5 ± 2.8 g versus 30.9 ± 2.9 g, n=5 in each group. p=ns), however KLF6
+/-
mice were resistant to high fat-induced obesity (39.8 ± 4.0 g versus 50.1 ± 3.7 g, n=7 in each group. p<0.0002). As for food intake, there was no significant difference between two genotypes (2.9 ± 0.3 versus 3.2 ± 0.3 g/day, n=5 in each group. p=ns). Adipocytes from KLF6
+/-
mice were smaller and showed a reduced hypertrophic response to this dietary manipulation, and adipocyte markers were less expressed in white adipose tissue of KLF6
+/-
mice. Brown adipose tissue of KLF6
+/-
mice also showed less steatotic change, which indicated enhanced heat production. On a high fat diet, KLF6
+/-
mice and wild-type littermates were similar in fasting blood glucose levels, however KLF6
+/-
mice showed significantly lower glucose concentrations after glucose challenge (27.5 ± 4.0 versus 13.1 ± 1.9 mmol / L, n=5 in each group . p=0.006). Serum adiponectin levels were markedly higher in KLF6
+/-
mice (3.4 ± 0.7 versus 2.4 ± 0.3, n=8 in each group. p=0.03). Embryonic fibroblasts from KLF6
+/-
mice were significantly impaired in adipogenic differentiation.

Conclusions:
KLF6
+/-
mice showed no metabolic phenotype under a normal intake, whereas they were resistant to excessive nutrition, compared with wild-type littermate. KLF6 promotes adipocyte hypertrophy, which leads to the pathogenesis of obesity, glucose intolerance and diabetes mellitus.
Abstract 18877: Novel Mouse Model for Testing NADPH Oxidase (Nox2) Role in Insulin Resistance Mediated Endothelial Dysfunction
Authors: Sukumar Piruthivi , Viswambharan Hema , Imrie Helen , Cubbon Richard M , Yuldasheva Nadira , Gage Matthew , Galloway Stacey , Skromna Anna , Kandavelu Parkavi , Smith Jessica , Gatenby Victoria K , Beech David J , Wheatcroft Stephen B , Channon Keith M , Shah Ajay M , Kearney Mark T
Published: April 2024

Introduction:
Insulin resistance (IR) plays a pivotal role in type 2 diabetes, obesity and hypercholesterolemia. Reactive oxygen species (ROS) play a key role in IR related endothelial dysfunction. We have reported that, superoxide (SO), an important ROS is produced at higher levels in IR and established that NADPH oxidase (Nox) is the primary source of SO in IR endothelium. Here we report our study to ascertain the role of Nox2 in IR.

Methods:
A unique murine model of endothelium specific IR, Endothelial Specific Mutated Insulin Receptor Over-expression (ESMIRO) and mice with universal deletion of Nox2 gene (Nox2
y/-
) were used here. Nox2
y/-
mice was crossed with ESMIRO to generate double transgenics (ESMIRO/Nox2
y/-
). Endothelial function was analysed by measuring 1. aortic ring relaxation. 2. superoxide production. Expression of Nox and ROS related genes were examined by PCR and Western blotting.

Results:
Realtime PCR and Western blot of organs and pulmonary endothelial cells (PEC) confirmed the total loss of Nox2 in ESMIRO/Nox2
y/-
. Growth rate and organ weights were unaltered in ESMIRO/Nox2
y/-
. However, there was a trend towards reduced BP in double transgenics (119±1 mmHg in ESMIRO Vs 114±2 mmHg in ESMIRO/Nox2
y/-
; p=0.06). Metabolic characteristics including ITT and GTT showed no difference between two lines. Blood insulin levels before and after glucose injection were similar. Basal superoxide in PEC of ESMIRO/Nox2
y/-
were 240±11% (p=0.02) reduced when compared to ESMIRO. Nitric oxide (NO) mediated vascular relaxation was improved in double transgenic animals (100±4% in response to 1000 nM Ach in ESMIRO/Nox2
y/-
Vs 77±6% in ESMIRO). There was no change in endothelial independent relaxation (109±5% in response to 1000 nM SNP in ESMIRO/Nox2
y/-
Vs 104±6% in ESMIRO). Realtime PCR showed that the important ROS scavenger superoxide dismutase 1 (SOD1) expression was increased above 300% in ESMIRO lungs compared to ESMIRO/Nox2
y/-
. Other Nox and ROS related genes (Nox4, p22, p47, p67, SOD2, SOD3, eNOS & catalase) expression were unchanged.

Conclusions:
These results show that Nox2

NADPH oxidase is a key source of the excess superoxide seen in a model of endothelium specific insulin resistance. Targeting Nox2 may be a useful therapeutic strategy in IR conditions.
Abstract 18897: Genetically Purified Induced Pluripotent Stem Cell (IPSC)-derived Cardiomyocytes Engraft and Improve Remodeling and Ventricular Function After Myocardial Infarction in Mice
Authors: Martens Andreas , Rojas Sebastian V , Kensah George , Rotaermel Alexander , Baraki Hassina , Haverich Axel , Martin Ulrich , Gruh Ina , Kutschka Ingo
Published: April 2024

Induced pluripotent stem cells (iPSC) can be differentiated into cardiomyocytes in vitro and represent a possible autologous cell source for myocardial repair. The aim of this study was to determine the engraftment and functional effects of murine iPSC-derived cardiomyocytes (iPSC-CMs) in a mouse model of myocardial infarction. A genetic purification protocol was used to maximize CM yield and purity.

Methods:
Murine iPSCs were genetically modified to express a Zeocin resistance gene under control of the cardiac-specific α-myosin heavy chain (α-MHC) promoter. Differentiation was initiated by hanging drop technique. Embryoid bodies were brought into suspension culture. CM selection was started on d7 (400 µg/ml Zeocin). 1x10^6 cell tracer (CFDA-SE) marked iPSC-CMs were transplanted into the hearts of LAD-ligated mice. Animals were treated with placebo (PBS, n = 14) or iPSC-CMs (n = 35). Heart function was evaluated by magnetic resonance imaging (MRI) and conductance catheter (CC) analysis. In vitro and in vivo differentiation was investigated. Follow up after iPSC-CM transplantation was 1 and 2.5 weeks (histological assessment only) or 4 weeks (including functional analysis).

Results:
iPSC-CM purity was >90% after antibiotic resistance selection. Intramyocardial transplantation of iPSC-CMs significantly improved myocardial remodeling (e.g. infarct size and ventricular wall thickness, P<0.01) and left ventricular function 4 weeks after LAD-ligation (e.g. LV-EF, P<0.01). iPSC-CMs engrafted within ischemic myocardium, expressed cardiac markers and exhibited sarcomeric structures up to 2.5 weeks after transplantation. Connexin staining did not show functional coupling with host myocardium.

Conclusions:
iPSCs can effectively be differentiated into cardiomyocytes with high purity by genetic engineering techniques. iPSC derived cardiomyocytes engraft within the myocardium of LAD-ligated mice and improve left ventricular function. Future research has to focus on long term survival and functional coupling to host myocardium.
Abstract 18901: Direct Evidence that a KCNQ1 Mutation is Linked to Familial Early-onset Atrial Fibrillation
Authors: Bartos Daniel C , Anderson Jeffrey B , Bastiaenen Rachel , Johnson Jonathan N , Gollob Michael H , Tester David J , Burgess Don E , Homfray Tessa , Behr Elijah R , Ackerman Michael J , Guicheney Pascale , Delisle Brian P
Published: April 2024

KCNQ1
encodes the voltage-gated α-subunit of the I
Ks
channel complex (Kv7.1), and
KCNQ1
mutations are associated with multiple arrhythmia syndromes. Over the past 12 years, hundreds of different
KCNQ1
mutations have been linked to congenital long QT syndrome but only three
KCNQ1
variants, each identified in only one family, are linked to familial early-onset AF (<50 years of age). The scant genetic linkage between
KCNQ1
and early-onset AF raises the question as to whether these
KCNQ1
variants actually cause familial early-onset AF or simply unmask a latent genetic predisposition. We now report that a single
KCNQ1
variant, pArg231His or R231H, is identified in five unrelated families with a high penetrance of familial early-onset AF. Whole-cell patch clamp of cells heterologously expressing the obligatory I
Ks
β-subunit KCNE1 with wild-type KCNQ1 (WT) or WT and R231H (to mimic the patients’ genotypes) showed that cells co-expressing R231H increased current at negative and resting membrane potentials. Additionally, currents recorded from cells using a human atrial action potential (AP) waveform at physiological temperature showed that WT is minimally activated during the atrial AP and co-expression of R231H increases current measured during the atrial AP waveform by greater than 20-fold (WT, n = 10; WT & R231H, n = 12, p<0.0001). Simulations using a computational model of a human atrial AP also predicted that I
Ks
is normally minimally activated in the atria and R231H would dramatically increase I
Ks
and shorten the atrial AP. We conclude that
KCNQ1
mutations are capable of causing familial early-onset AF by increasing I
Ks
during the atrial AP and shortening atrial refractoriness.
Abstract 18903: Stimulation of Angiotensin Type 2 Receptor as a Potential Therapy for Pulmonary Hypertension
Authors: Bruce Erin , Shenoy Vinayak , Francis Joseph , Steckelings U. Muscha , Unger Thomas , Sumners Colin , Raizada Mohan K , Katovich Michael J
Published: April 2024

Pulmonary hypertension (PH) is characterized by an increased pressure in the lung vasculature, often leading to right heart failure, and for which current therapies are lacking. Activation of the ACE2/Ang-(1-7)/Mas axis of the renin angiotensin system attenuates much of the associated pathophysiology related to PH. Along with the ACE2/Ang-(1-7)/Mas axis, the AT2 receptor (AT2R) is considered vasoprotective, and activation of these components often mimic each other. In fact, both ACE2 and AT2R have a protective role in acute lung injury; however, the role of AT2R has yet to be investigated in PH. We hypothesize that activation of the AT2R, via selective agonist Compound 21 (C21), could be an effective treatment against PH. Sprague Dawely rats were injected sc with 50mg/kg of monocrotaline (MCT) at 8 weeks of age to induce PH. Control (Con) animals were given saline. After 2 weeks, when right ventricular systolic pressures (RVSP) were significantly elevated (PH 48.33±8.8; Con 32.0 ±2.4 mmHg), treatment began with animals receiving either 0.03mg/kg/day C21 ip (MCT+C21), 0.3mg/kg/day PD-123,319 (MCT+PD), C21 and PD (MCT+C21+PD), or vehicle (MCT, Con) for an additional 2 weeks, after which RV hemodynamic parameters were measured and tissues collected. Treatment with C21 significantly attenuated PH and associated cardiac pathophysiologies. The increase in RVSP and RV hypertrophy induced by MCT was significantly blunted by C21 treatment, and PD prevented this reduction. Furthermore, right heart dysfunction as measured by dP/dtmax, was significantly attenuated by C21 treatment, but was exacerbated in rats treated with PD. PD treatment also worsened the lung weight to tibia length ratio in comparison to MCT. To our knowledge these are the first results to indicate that activation of the AT2R halts the progression of PH and C21 should be considered for an additional drug arsenal in PH therapy.
Abstract 18904: High-denisty Lipoprotein Distribution in Obesity Favors Apolipoprotein E and C-III-containing Subfractions Associated with Risk for Future Coronary Heart Disease
Authors: Talayero Beatriz , Furtado Jeremy , Sacks Frank
Published: April 2024

Human high-density lipoprotein (HDL) particles are highly heterogeneous in composition. Both the plasma concentration of HDL with apoC-III and the concentration of apoE in HDL predict higher incidence of coronary heart disease (CHD). Little is known about the concentration of HDL apoA-I associated with apoE or apoC-III, whether apoE and apoC-III are present in smaller or larger cholesterol ester-rich HDL, and whether the distribution is affected in obesity. We studied 20 normal weight subjects (BMI 23-25) and 20 obese subjects (BMI 30-35) matched by age (mean age, 51 years). Sixteen distinct HDL subpopulations were separated from plasma samples by first using anti-apoAI, anti-apoE and anti-apoC-III immunoaffinity chromatography in sequence followed by size separation using nondenaturing electrophoresis. The mean HDL-cholesterol and plasma apoA-I concentrations in the normal weight group were 65 and 179mg/dL respectively, compared to 50 and 170mg/dL in the obese group. Mean apoA-I concentrations of HDL fractions without apoE or apoC-III was 160mg/dL in the normal weight group, compared to 136mg/dL in the obese; with apoE only 9 and 12mg/dL respectively; with apoC-III only 7.4 and 14.7 mg/dL; and with both apoE and apoC-III 2.6 and 7.5mg/dL (p<0.01 for a difference in apoA-I concentration and distribution across HDL types). All told, about 10% of HDL apoA-I in normal weight subjects contained apoE, apoC-III or both, compared to 20% in obese subjects. The concentrations of apoE and apoC-III in HDL in the obese were about double that of the normal weight group (p<0.01). In the obese group, the high concentration of HDL with apoE was distributed to small HDL. More so, obese had a higher percent of large HDL containing apoC-III and no apoE. In conclusion, despite similar plasma total apoA-I levels in obese and normal weight groups, the obese had higher concentrations of HDL containing apoE or apoC-III, subfractions which are associated with CHD, whereas the normal weight group had higher concentration of HDL without apoE or apoC-III, a subtraction with protective association against CHD. Mechanistically, the increased presence of apoC-III in large size HDL and apoE in small size HDL in obese may indicate a reduced capacity of HDL for RCT.
Abstract 18908: Incremental Value of Inefficient Deformation Indices for Predicting Response to Cardiac Resynchronization Therapy
Authors: Chan Yi-Hsin , Wang Chun-Li , Kuo Chi-Tai
Published: April 2024

Background:
Previous studies have identified 4 clinical characteristics associated with a favorable response to cardiac resynchronization therapy (CRT): female, left bundle-branch block (LBBB), QRS duration ≥ 150 ms and non-ischemic etiology. This study evaluated the incremental value of baseline inefficient-deformation and time-delay indices over clinical characteristics for predicting CRT response.

Methods:
Speckle-tracking longitudinal strain was analyzed in 119 CRT candidates. Patients were divided into subgroups according to sex (male vs female), QRS morphology (LBBB vs non-LBBB), QRS duration (≥ 150 ms vs <150 ms) and heart failure etiology (ischemic vs nonischemic). Inefficient deformation was indexed by the septal systolic stretching that occurred after shortening (SRSsept) and the absolute differences between peak strain and end-systolic strain across 16 segments (SDI). Time to peak strain was measured to derive the septal to lateral delay and the 12-segment standard deviation of time to peak strain. CRT response was defined as a 6-month end-systolic volume reduction ≥ 15%.

Results:
Patients with 1 of the 4 favorable characteristics were more likely to exhibit other favorable characteristics and had greater amounts of inefficient deformation than those without. In contrast, time-delay indices were not significantly different in any pairwise comparison except for that between LBBB and non-LBBB patients. Of the 38 patients for whom 6-month follow-up data was available, CRT response was found in 22 (58%). SRSsept and SDI rather than time-delay indices provided significant incremental value over clinical characteristics when predicting CRT response.

Conclusions:
Combined SRSsept (or SDI) and favorable characteristics may help identify CRT responders.
Abstract 18921: Utility of a TTC Score to facilitate differentiation of Tako-Tsubo Cardiomyopathy from Ischemic ACS
Authors: Neil Christopher J , Nguyen Thanh H , Stansborough Jeanette , Rong Cher-Rin , Singh Kuljit , Kucia Angela , Horowitz John D
Published: April 2024

Introduction:
The diagnosis of tako-tsubo cardiomyopathy (TTC) is often made by default after emergent cardiac catheterization and potentially the inappropriate administration of thrombolytics or catecholamines. In view of the distinct pathogenesis of TTC, it is important that TTC be distinguished from ischemic ACS, clinically, if possible. We now report the utility of an arbitrarily derived “TTC score” based on clinical features of TTC versus ACS.

Methods:
Consecutive TTC (n=99) and female ACS (N=56) patients of similar ages were compared. The TTC score allocated 1 point for troponin T elevation, 1 or 2 points for NT-proBNP to ≥3000 or ≥6000pg/ml respectively, and 1 or 2 points for regional and multiregional ECG changes respectively, with analyses based on data at 24 hours post presentation. Additional analyses were performed to evaluate the potential additional impact of histories of antecedent severe stress, and that of the presence/absence of hemodynamic compromise (Killip Class ≥2).

Results:
Scores were substantially different (see Figure; TTC group median 4, vs. 2 in the ACS group; p<0.0001). Receiver operator curve analysis demonstrated an area under the curve (AUC) of 0.74 (P<0.0001), with 62% sensitivity and 75% specificity for a score ≥4. This differentiation was based primarily on NT-proBNP levels (median 5990 vs 1600 pg/ml). The rate of antecedent stressor exposure for TTC patients was 82%: modeling of imputed stressor exposure rates of 25 and 50% for ACS patients improved specificity to 79 and 75% respectively. The TTC score separated diagnostic groups in Killip 1 (AUC 0.80, P<0.0001), but not in Killip ≥2 (AUC 0.66, P=NS).

Conclusion:
This TTC score facilitates differentiation of TTC from ischemic ACS, in the absence of pulmonary congestion/shock. Early diagnosis of TTC is an essential precursor to the development of disease-specific therapeutic regimens.