Sacubitril/valsartan attenuates atrial conduction disturbance and electrophysiological heterogeneity with ameliorating fibrosis in mice

Background

Sacubitril/valsartan (SacVal) has been shown to improve the prognosis of heart failure; however, whether SacVal reduces the occurrence of atrial fibrillation (AF) in heart failure has not yet been elucidated. In this study, we aimed to determine whether SacVal is effective in reducing the occurrence of AF in heart failure and identify the underlying mechanism of its electrophysiological effect in mice.

Methods

Adult male mice underwent transverse aortic constriction, followed by SacVal, valsartan, or vehicle treatment for two weeks. Electrophysiological study (EPS) and optical mapping were performed to assess the susceptibility to AF and the atrial conduction properties, and fibrosis was investigated using heart tissue and isolated cardiac fibroblasts (CFs).

Results

EPS analysis revealed that AF was significantly less inducible in SacVal-treated mice than in vehicle-treated mice. Optical mapping of the atrium showed that SacVal-treated and valsartan-treated mice restored the prolonged action potential duration (APD); however, only SacVal-treated mice showed the restoration of decreased conduction velocity (CV) compared to vehicle-treated mice. In addition, the electrophysiological distribution analysis demonstrated that heterogeneous electrophysiological properties were rate-dependent and increased heterogeneity was closely related to the susceptibility to AF. SacVal attenuated the increased heterogeneity of CV at short pacing cycle length in atria, whereas Val could not. Histological and molecular evaluation showed that SacVal exerted the anti-fibrotic effect on the atria. An in vitro study of CFs treated with natriuretic peptides and LBQ657, the metabolite and active form of sacubitril, revealed that C-type natriuretic peptide (CNP) combined with LBQ657 had an additional anti-fibrotic effect on CFs.

Conclusions

Our results demonstrated that SacVal can improve the conduction disturbance and heterogeneity through the attenuation of fibrosis in murine atria and reduce the susceptibility of AF in heart failure with pressure overload, which might be attributed to the enhanced function of CNP.

Genetic risk score of cerebral infarction in atrial fibrillation genome-wide association study

INTRODUCTION

Stroke is a leading cause of death and the primary cause of adult-acquired disability. Patients with cardiogenic embolic stroke also have higher mortality and recurrence rates than patients with other stroke subtypes. Atrial fibrillation (AF) is a major risk factor for cerebral infarction (CI). The large-scale study identified 32 loci in the MEGASTROKE study. However, few studies have attempted to identify novel stroke risk variants in patients with a history of AF. Our overall aim was to identify novel CI risk variants in AF cases and explore whether their associations with the CI risk were affected by the CHADS2 and CHA2DS2-VASc scores.

METHODS

We performed association study with CI using 8181 AF cases in previous genome-wide association study (GWAS) and imputation data without controls. We classified AF cases into those with or without past history of CI, and the genetic associations with the CI risk were examined.

RESULTS

GWAS identified eight associated loci. The generated genetic risk score (GRS) for the eight loci was significantly associated with CI in patients with AF (1.46 × 10-8 ). We estimated bivariate logistic regression model which contained GRS and CHADS2 score (GRS: p-Value = 7.41 × 10-9 , CHADS2 score: p-Value <2.0 × 10-16 ) or CHA2DS2-VASc scores (GRS: p-Value = 2.52 × 10-10 , CHA2DS2-VASc score: p-Value <2.0 × 10-16 ).

CONCLUSION

We identified eight genetic variants that were potentially associated with the risk of CI of AF cases and the significant GRS, whose associations were independent of the CHADS2 or CHA2DS2-VASc score.

Risk stratification of atrial fibrillation and stroke using single nucleotide polymorphism and circulating biomarkers

BACKGROUND

Atrial fibrillation (AF) is the most common sustained arrhythmia, and it causes a high rate of complications such as stroke. It is known that AF begins as paroxysmal form and gradually progresses to persistent form, and sometimes it is difficult to identify paroxysmal AF (PAF) before having stroke. The aim of this study is to evaluate the risk of PAF and stroke using genetic analysis and circulating biomarkers.

MATERIALS AND METHODS

A total of 600 adult subjects were enrolled (300 from PAF and control groups). Peripheral blood was drawn to identify the genetic variation and biomarkers. Ten single nucleotide polymorphisms (SNPs) were analyzed, and circulating cell-free DNA (cfDNA) was measured from plasma. Four microRNAs (miR-99a-5p, miR-192-5p, miR-214-3p, and miR-342-5p) were quantified in serum using quantitative RT-PCR.

RESULTS

Genotyping identified 4 single nucleotide polymorphisms (SNPs) that were significantly associated with AF (rs6817105, rs3807989, rs10824026, and rs2106261), and the genetic risk score using 4 SNPs showed the area under the curve (AUC) of 0.631. Circulating miRNAs and cfDNA did not show significant differences between PAF and control groups. The concentration of cfDNA was significantly higher in patients with a history of stroke, and the AUC was 0.950 to estimate the association with stroke.

CONCLUSION

The risk of AF could be assessed by genetic risk score. Furthermore, the risk of stroke might be evaluated by plasma cfDNA level.

Prediction of the Presence of Ventricular Fibrillation From a Brugada Electrocardiogram Using Artificial Intelligence

BACKGROUND

Brugada syndrome is a potential cause of sudden cardiac death (SCD) and is characterized by a distinct ECG, but not all patients with A Brugada ECG develop SCD. In this study we sought to examine if an artificial intelligence (AI) model can predict a previous or future ventricular fibrillation (VF) episode from a Brugada ECG.Methods and Results: We developed an AI-enabled algorithm using a convolutional neural network. From 157 patients with suspected Brugada syndrome, 2,053 ECGs were obtained, and the dataset was divided into 5 datasets for cross-validation. In the ECG-based evaluation, the precision, recall, and F1score were 0.79±0.09, 0.73±0.09, and 0.75±0.09, respectively. The average area under the receiver-operating characteristic curve (AUROC) was 0.81±0.09. On per-patient evaluation, the AUROC was 0.80±0.07. This model predicted the presence of VF with a precision of 0.93±0.02, recall of 0.77±0.14, and F1score of 0.81±0.11. The negative predictive value was 0.94±0.11 while its positive predictive value was 0.44±0.29.

CONCLUSIONS

This proof-of-concept study showed that an AI-enabled algorithm can predict the presence of VF with a substantial performance. It implies that the AI model may detect a subtle ECG change that is undetectable by humans.

The Anti-inflammatory Effects and Clinical Potential of Dexmedetomidine in Pulmonary Arterial Hypertension

A pathogenic aspect of pulmonary arterial hypertension (PAH) is the aberrant pulmonary arterial smooth muscle cells (PASMCs) proliferation. PASMCs proliferation is significantly affected by inflammation. A selective alpha-2 adrenergic receptor agonist called dexmedetomidine (DEX) modulates specific inflammatory reactions. We investigated the hypothesis that anti-inflammatory characteristics of DEX could lessen PAH that monocrotaline (MCT) causes in rats. In vivo, Male Sprague-Dawley rats aged 6 weeks were subcutaneously injected with MCT at a dose of 60 mg/kg. Continuous infusions of DEX (2 µg/kg/h) were started via osmotic pumps in one group (MCT + DEX group) at day 14 following MCT injection, but not in another group (MCT group). Right ventricular systolic pressure (RVSP), right ventricular end-diastolic pressure (RVEDP), and survival rate significantly improved in the MCT + DEX group compared to the MCT group (RVSP, 34 mmHg {plus minus} 4 mmHg vs. 70 mmHg {plus minus} 10 mmHg; RVEDP, 2.6 mmHg {plus minus} 0.1 mmHg vs. 4.3 mmHg {plus minus} 0.6 mmHg; survival rate, 42% vs. 0% at day 29 (P < 0.01)). In the histological study, the MCT + DEX group showed less phosphorylated-p65-positive PASMCs and medial hypertrophy of the pulmonary arterioles. In vitro, DEX dose dependently inhibited human PASMC proliferation. Furthermore, DEX decreased the expression of interleukin-6 mRNA in human PASMCs treated with fibroblast growth factor 2 (FGF2). These consequences suggest that DEX improves PAH by inhibiting PASMC proliferation through its anti-inflammatory properties. Additionally, DEX may exert anti-inflammatory effect via blocking FGF2-induced nuclear factor-kappa B activation. Significance Statement Dexmedetomidine, a selective alpha-2 adrenergic receptor agonist utilized as a sedative in the clinical setting, improves PAH by inhibiting PASMC proliferation through its anti-inflammatory effect. Dexmedetomidine can be a new PAH therapeutic agent with vascular reverse remodeling effect.

AB0401 THE BASELINE SERUM SOLUBLE TNF RECEPTOR LEVELS ARE ASSOCIATED WITH THE RESPONSE OF RHEUMATOID ARTHRITIS PATIENTS TO JAKinibs

Background

Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects the multiple joints.

The elucidation of the pathogenesis of RA has progressed dramatically in recent decades, and among the many cytokines involved in the pathogenesis of RA, interleukin (IL)-6 and TNF-α are known to be the major pro-inflammatory cytokines that are abundant in the bloodstream and synovial tissue. JAK inhibitors (JAKinibs) such as tofacitinib and baricitinib are used in the treatment of RA by inhibiting JAK, which in turn inhibits the signaling of various cytokines including IL-6. However, predictors of the response to JAKinibs are still required.

Objectives

We aimed to combine soluble TNF receptor (sTNFR) I, sTNFR II, IL-6, soluble IL-6R (sIL-6R) and soluble gp130 (sgp130) levels to identify groups of JAKinibs responses in RA patients.

Methods

This research is a retrospective study. We reviewed medical records of RA patients initiating JAKinibs between July 2013 and July 2021 in our hospital. The Simplified Disease Activity Index (SDAI) was evaluated at baseline and 3, 6 months after JAKinibs administration. Clinical remission was defined when SDAI decreased ≤ 3.3. Of the 125 patients treated with JAKinibs, 89 patients with 6 months follow-up, valid SDAI and serum available were enrolled. Serum samples were tested for IL-6 (Human IL-6 Quantikine ELISA Kit, R&D systems), sIL-6R (Human soluble IL-6R alpha Quantikine ELISA Kit, R&D systems) and sgp130 (Human soluble gp130 Quantikine ELISA Kit, R&D systems), sTNFR I (Human TNF RI/TNFRSF1A Quantikine ELISA Kit DRT100) and sTNFR II (Human sTNF RII/TNFRSF1B Quantikine ELISA Kit DRT200) using specific ELISAs according to the manufacturer’s instructions. The statistical analyses were performed with EZR 1.55, and p values less than 0.05 were considered significant.

Results

The median age of patients was 62 (IQR: 51 - 72) years and the median of disease duration was 6.0 (2.0 - 16.0) years. Twenty-seven (30.3%) patients were biologics and Jakinibs naive. The baseline SDAI was median 18.9 (12.7 - 27.9). When comparing SDAI-remission group (clinical remission: CR) and non-remission group, there were no significant differences in any of the baseline clinical parameters. There was no significant difference in the serum levels of IL-6, sIL-6R and sgp130 between the CR and non-CR groups, but the serum levels of sTNFR I and sTNFR II in the CR group were significantly lower than non-CR group. Univariate logistic regression analysis suggested Biologics and JAKinibs naive (odds ratio (OR) 3.58, p = 0.015), baseline Log sTNFR II levels (OR 0.013, P=0.034) as predictors of SDAI remission treated with JAKinibs at 6 months. Although not significant, Stage IV (OR 0.211, P=0.082) and baseline Log sTNFR I serum levels (OR 0.013, P=0.065) were associated with clinical remission.

Conclusion

RA patients could be easily stratified prior to JAKinibs intervention with serum sTNFR II and sTNFR I levels, not but IL-6 axis cytokines (IL-6, sIL-6R and sgp130).

Univariate logistic regression analysis for clinical remission in patients treated with JAKinibs.　Odds Ratio[95% C.I.]P ValueAge, year0.973[0.942 - 1.010]0.104Female (%)0.820[0.231 - 2.910]0.759BMI0.968[0.847 - 1.110]0.627Duration, year0.952[0.897 - 1.010]0.110StageIreferrenceII0.857[0.218 - 3.370]0.825III0.444[0.072 - 2.740]0.382IV0.211[0.036 - 1.220]0.082Biologic/JAKi naïve3.580[1.280 - 9.950]0.015JAKi Drug-Baricitinibreferrence-Tofacitinib1.780[0.659 - 4.800]0.256MTX use1.640[0.532 - 5.30]0.390PSL use0.476[0.176 - 1.290]0.143SASP use0.783[0.268 - 2.290]0.654IGU use0.328[0.039 - 2.750]0.304BUC use0.436[0.051 - 3.760]0.450TAC use0.233[0.029 - 1.910]0.1750W IL-6, pg/mL0.991[0.977 - 1.000]0.1980W sIL-6R, ng/mL0.983[0.947 - 1.02]0.3690W sgp130, ng/mL0.998[0.994 - 1.000]0.4440W sTNFR II/I ratio0.808[0.222 - 2.940]0.7460W Log sTNFR II, pg/mL0.002[0.0000653 - 0.634]0.0340W Log sTNFR I, pg/mL0.013[0.000126 - 1.300]0.065

Disclosure of Interests

None declared

AB0362 NEUTROPHIL COUNT REDUCTION 1 MONTH AFTER INITIATING SARILUMAB AND BASELINE SERUM SOLUBLE gp130 LEVELS CAN INDEPENDENTLY PREDICT CLINICAL REMISSION WITHIN 3 MONTH IN RHEUMATOID ARTHRITIS PATIENTS

Background

IL-6 contributes significantly to the chronic inflammatory process of rheumatoid arthritis (RA) and is elevated in serum and synovial fluid of RA patients.

Sarilumab (SRL), a human anti-human IL-6 receptor alpha monoclonal antibody that blocks the signaling originated by the IL-6/IL-6R complex like tocilizumab (TCZ),is an effective treatment. Recently, an association between the therapeutic effect of TCZ and neutropenia after TCZ initiation was reported[1]. Neutropenia is a common adverse event of SRL in patients with RA, but the relationship between reduced neutrophil count and clinical response to SRL is still inconclusive. In EULAR 2020, we reported the association between serum soluble gp130 levels before SRL treatment and the efficacy of SRL[2]. It is also unclear whether there is a relationship between IL-6 axis cytokines and SRL-induced neutropenia.

Objectives

The purpose of this study was to determine whether neutropenia at 1 month by SRL predicts clinical remission within 3 months and whether there is an association between IL-6 axis cytokines levels and SRL-induced neutropenia.

Methods

This research is a retrospective study. We reviewed medical records of RA patients initiating SRL between February 2018 and August 2021 in our hospital. The Clinical Disease Activity Index (CDAI) was evaluated at baseline (before initiating SRL) and 3 months after administration. Clinical remission was defined when CDAI decreased ≤ 2.8. Of the 66 patients treated with SRL, 42 patients with 3 months follow-up, valid CDAI and serum available were enrolled. The ratio of neutrophil counts 1 month after initiating SRL to those at baseline (neutrophil ratio) was also calculated. Serum samples were tested for IL-6 (Human IL-6 Quantikine ELISA Kit, R&D systems), sIL-6R (Human soluble IL-6R alpha Quantikine ELISA Kit, R&D systems) and sgp130 (Human soluble gp130 Quantikine ELISA Kit, R&D systems) using specific ELISAs according to the manufacturer’s instructions. The statistical analyses were performed with EZR 1.55, and p values less than 0.05 were considered significant.

Results

The median age of patients was 69.0 (IQR: 59.3 - 73.8) years and the median of disease duration was 9.0 (3.0 - 16.0) years. Eighteen (42.9%) patients were biologics and Jakinibs naive. The baseline CDAI was median 16.7 (11.5 - 25.8). When comparing CDAI-remission group (clinical remission: CR) and non-CR group, Patients in the CR group had significantly shorter disease duration, were more Biologic and JAKinib naive, and had greater neutropenia 1 month after starting SRL (0.71 vs 0.94, P=0.0252). There was no significant difference in the baseline serum levels of IL-6, sIL-6R between the CR and non-CR groups, but baseline serum sgp130 levels in the CR group tended to be higher than in the non-CR group (264.9 vs 234.2 ng/mL, P=0.0592). Univariate logistic regression analysis suggested Biologics and JAKinibs naive (odds ratio (OR) 6.68, p = 0.0317), baseline serum sgp130 levels (OR 8.608, P=0.0312) as predictors of CDAI remission treated with SRL at 3 months. Although not significant, neutrophil ratio ≤ 0.8 was associated with achieving remission (OR 6.67, P=0.0537). Univariate logistic regression for neutrophil ratio ≤ 0.8 did not show any relevant factors, including higher baseline serum sgp130 levels (OR 1.25, P=0.782).

Conclusion

A 20% or greater decrease in neutrophil count after 1 month of SRL treatment and a high baseline serum sgp130 level independently predict clinical remission within 3 months.

References

[1]Nakajima T, Watanabe R, Hashimoto M, Murata K, Murakami K, Tanaka M, et al. Neutrophil count reduction 1 month after initiating tocilizumab can predict clinical remission within 1 year in rheumatoid arthritis patients. Rheumatol Int. 2021;1rin

[2]Yoshikawa T, Furukawa T, Tamura M, Hashimoto T, Morimoto M, Azuma N, et al. FRI0113 THE BASELINE SOLUBLE GP130 IS ASSOCIATED WITH THE RESPONSE OF RHEUMATOID ARTHRITIS PATIENTS TO SARILUMAB. Ann Rheum Dis. 2020;79(Suppl 1):637.1-637.

Disclosure of Interests

None declared

Local Injection of Hydroxyapatite Electret Ameliorated Infarct Size After Myocardial Infarction

Background: Previous studies showed that hydroxyapatite electret (HAE) accelerates the regeneration of vascular endothelial cells and angiogenesis. This study investigated the effects of HAE in myocardial infarction (MI) model mice.

Methods and Results: MI was induced in mice by ligating the left anterior descending artery. Immediately after ligation, HAE, non-polarized hydroxyapatite (HAN), or water (control) was injected into the infarct border myocardium. Functional and histological analyses were performed 2 weeks later. Echocardiography revealed that HAE injection preserved left ventricular systolic function and the wall thickness of the scar, whereas HAN-injected mice had impaired cardiac function and thinning of the wall, similar to control mice. Histological assessment showed that HAE injection significantly attenuated the length of the scar lesion. There was significant accumulation of CD31-positive cells and increased expression of vascular endothelial growth factor (Vegf), intercellular adhesion molecule-1 (Icam1), vascular cell adhesion molecule-1 (Vcam1), hypoxia-inducible factor-1α (Hif1a), and C-X-C motif chemokine ligand 12 (Cxcl12) genes in the infarct border zone of HAE-injected mice. These effects were not induced by HAN injection. Anti-VEGFR2 antibody canceled the beneficial effect of HAE. In vitro experiments in a human cardiovascular endothelial cell line showed that HAE dose-dependently increased VEGFA expression.

Conclusions: Local injection of HAE attenuated infarct size and improved cardiac function after MI, probably due to angiogenesis. The electric charge of HAE may stimulate angiogenesis via HIF1α-CXCL12/VEGF signaling.

AB0311 INCREASED LEVELS OF SERUM WISTERIA FLORIBUNDA AGGLUTININPOSITIVE MAC-2 BINDING PROTEIN IN RHEUMATIC DISEASES INCLUDING SLE

Background:

Mac-2 binding protein is a cell-adhesive glycoprotein of the extracellular matrix secreted as a ligand of galectin-3 (Mac-2). Recently, a Wisteria floribunda agglutinin positive-M2BP (M2BP) assay developed using a lectin-antibody sandwich immunoassay has shown promise as a new fibrotic marker in liver fibrosis and interstitial lung disease (ILD) to detect unique fibrosis-related glycoalteration.

Objectives:

The aim of this study is to evaluate the utility of serum Mac-2 binding protein glycosylation isomer (M2BPGi) levels in patients with rheumatic diseases (RD).

Methods:

We retrospectively measured serum M2BPGi levels in 68 patients with RD and 16 healthy controls (HC). There were no patients of cirrhosis and active hepatitis. Serum levels of M2BPGi were measured using HISCL M2BP glycosylation isomer Assay Kit. We examined the relationship between serum M2BPGi levels and clinical parameters in patients with RD.

Results:

In patients with RD, the median age was 62.0 years and 79.4% of them were female.

Serum M2BPGi levels were significantly higher in patients with RD than in HC (median 0.98 cutoff index [COI], 0.32 COI, respectively; P < 0.00001). Patients with SLE tended to have higher serum M2BPGi levels than other rheumatic diseases.

In patients with RD, a significant correlation was not found between serum M2BP levels and inflammation markers such as CRP or ferritin. However, serum M2BPGi levels were significantly correlated with B cell activation markers such as immunoglobulin free light chain and IgG (r = 0.588, 0.504) and T cell activation marker such as sIL-2R (r = 0.408).

Conclusion:

Most of the rheumatic diseases in this study were considered to be type I interferonopathy diseases such as rheumatoid arthritis, Sjogren’s syndrome, inflammatory myositis, scleroderma and SLE.

Serum M2BPGi was reported to have a significant correlation with SLE disease activity [SS Ahn et al. Lupus. 2018; 27: 771], and also to have a significant correlation with Gakectin-9, a novel biomarker for IFN signiture [Lucas L van den Hoogen et al. Ann Rheum Dis. 2018; 77: 1810].

So, it was suggested that serum M2BPGi may be a novel biomarker that indirectly indicates how much IFN is activated in rheumatic diseases.

Disclosure of Interests:

None declared

Which psychotherapy is effective in panic disorder? Findings and reflections from a systematic network meta-analysis

Introduction

Panic disorder is among the most prevalent anxiety diseases. Although psychotherapy is recommended as first-line treatment for panic disorder, little is known about the relative efficacy of different types of psychotherapies.

Objectives

To evaluate the effectiveness and acceptability of different types of psychotherapies for adults suffering from panic disorder, with or without agoraphobia.

Methods

We are conducting a systematic network meta-analysis of randomized controlled trials examining panic disorder. A comprehensive search was performed to identify relevant studies. The primary efficacy outcome is anxiety symptoms at study endpoint. The primary acceptability outcome is all-cause trial discontinuation at endpoint. Pairwise and network meta-analysis will be conducted. We are considering any kind of psychotherapy delivered by any therapist, as long as they were trained to deliver the therapy, or as self-help.

Results

To date we have identified 126 panic disorder and agoraphobia trials. The publication time span ranges from 1968 to 2020. We are now extracting data to provide an overview of the included study characteristics. The statistical analysis will be conducted between December 2020 and January 2021, and its results presented for the first time at the forthcoming 2021 EPA congress.

Conclusions

126 trials on psychotherapy for panic disorders in adults are available. Because of this huge body of knowledge, it is important that the results of these studies are summarized using network meta-analytic techniques. The findings of this study will guide future research as knowledge gaps will be easily identified. Moreover, policymakers will have the opportunity to use this summarized knowledge to inform evidence-based decision making.

Disclosure

No significant relationships.

Sparsely methylated mitochondrial cell free DNA released from cardiomyocytes contributes to systemic inflammatory response accompanied by atrial fibrillation

Systemic inflammation is assumed to be the consequence and the cause of atrial fibrillation (AF); however, the underlying mechanism remains unclear. We aimed to evaluate the level of cell-free DNA (cfDNA) in patients with AF and AF mimicking models, and to illuminate its impact on inflammation. Peripheral blood was obtained from 54 patients with AF and 104 non-AF controls, and cfDNA was extracted. We extracted total cfDNA from conditioned medium after rapid pacing to HL-1 cells. Nuclear and mitochondrial DNA were separately extracted and fragmented to simulate nuclear-cfDNA (n-cfDNA) and mitochondrial-cfDNA (mt-cfDNA). The AF group showed higher cfDNA concentration than the non-AF group (12.6 [9.0–17.1] vs. 8.1 [5.3–10.8] [ng/mL], p < 0.001). The copy numbers of n-cfDNA and mt-cfDNA were higher in AF groups than in non-AF groups; the difference of mt-cfDNA was particularly apparent (p = 0.011 and p < 0.001, respectively). Administration of total cfDNA and mt-cfDNA to macrophages significantly promoted IL-1β and IL-6 expression through TLR9, whereas n-cfDNA did not. Induction of cytokine expression by methylated mt-cfDNA was lower than that by unmethylated mt-cfDNA. Collectively, AF was associated with an increased cfDNA level, especially mt-cfDNA. Sparsely methylated mt-cfDNA released from cardiomyocytes may be involved in sterile systemic inflammation accompanied by AF.

Subcellular localization of glypican-5 is associated with dynamic motility of the human mesenchymal stem cell line U3DT

Glypican-5 (GPC5) is a heparan sulfate proteoglycan (HSPG) localized to the plasma membrane. We previously reported that in the human mesenchymal stem cell line UE6E7T-3, GPC5 is overexpressed in association with transformation and promotes cell proliferation by acting as a co-receptor for Sonic hedgehog signaling. In this study, we found using immunofluorescence microscopy that in transformed cells (U3DT), GPC5 localized not only at primary cilia on the cell surface, but also at the leading edge of migrating cells, at the intercellular bridge and blebs during cytokinesis, and in extracellular vesicles. In each subcellular region, GPC5 colocalized with fibroblast growth factor receptor (FGFR) and the small GTPases Rab11 and ARF6, indicating that GPC5 is delivered to these regions by Rab11-associated recycling endosomes. These colocalizations suggest that GPC5 plays an important role in FGF2 stimulation of cell migration, which was abrogated by knockdown of GPC5. Our findings indicate that GPC5 plays a role in regulation of U3DT cell migration and provides several insights into the functions of GPC5 that could be elucidated by future studies.

Functional Role of the L396R Mutation of Tks5 Identified by an Exome-Wide Association Study in Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common cardiac arrhythmia; however, the current treatment strategies for AF have limited efficacy. Thus, a better understanding of the mechanisms underlying AF is important for future therapeutic strategy. A previous study (Exome-Wide Association Study (ExWAS)) identified a rare variant, rs202011870 (MAF=0.00036, GenomAD), which is highly associated with AF (OR=3.617, P<0.0001). rs202011870 results in the replacement of Leu at 396 with Arg (L396R) in a molecule, Tks5; however, the mechanism of how rs202011870 links to AF is completely unknown.Methods and Results:The association of rs202011870 with AF was examined in 3,378 participants (641 control and 2,737 AF cases) from 4 independent cohorts by using an Invader assay. Consequences of rs202011870 in migration ability, podosome formation, and expression of inflammation-related molecules in macrophages were examined using RAW264.7 cells with a trans-well assay, immunocytochemistry, and qPCR assay. Validation of the association of rs202011870 with AF was successful. In vitro studies showed that RAW264.7 cells with L396R-Tks5 increased trans-well migration ability, and enhanced podosome formation. RAW264.7 cells with L396R-Tks5 also increased the expression of several inflammatory cytokines and inflammation-related molecules.

CONCLUSIONS

L396R mutation in Tks5 associated with AF enhances migration of macrophages and their inflammatory features, resulting in enhanced susceptibility to AF.

A missense mutation in the RSRSP stretch of Rbm20 causes dilated cardiomyopathy and atrial fibrillation in mice

Dilated cardiomyopathy (DCM) is a fatal heart disease characterized by left ventricular dilatation and cardiac dysfunction. Recent genetic studies on DCM have identified causative mutations in over 60 genes, including RBM20, which encodes a regulator of heart-specific splicing. DCM patients with RBM20 mutations have been reported to present with more severe cardiac phenotypes, including impaired cardiac function, atrial fibrillation (AF), and ventricular arrhythmias leading to sudden cardiac death, compared to those with mutations in the other genes. An RSRSP stretch of RBM20, a hotspot of missense mutations found in patients with idiopathic DCM, functions as a crucial part of its nuclear localization signals. However, the relationship between mutations in the RSRSP stretch and cardiac phenotypes has never been assessed in an animal model. Here, we show that Rbm20 mutant mice harboring a missense mutation S637A in the RSRSP stretch, mimicking that in a DCM patient, demonstrated severe cardiac dysfunction and spontaneous AF and ventricular arrhythmias mimicking the clinical state in patients. In contrast, Rbm20 mutant mice with frame-shifting deletion demonstrated less severe phenotypes, although loss of RBM20-dependent alternative splicing was indistinguishable. RBM20^S637A protein cannot be localized to the nuclear speckles, but accumulated in cytoplasmic, perinuclear granule-like structures in cardiomyocytes, which might contribute to the more severe cardiac phenotypes.

In vitro generation of functional murine heart organoids via FGF4 and extracellular matrix

Our understanding of the spatiotemporal regulation of cardiogenesis is hindered by the difficulties in modeling this complex organ currently by in vitro models. Here we develop a method to generate heart organoids from mouse embryonic stem cell-derived embryoid bodies. Consecutive morphological changes proceed in a self-organizing manner in the presence of the laminin-entactin (LN/ET) complex and fibroblast growth factor 4 (FGF4), and the resulting in vitro heart organoid possesses atrium- and ventricle-like parts containing cardiac muscle, conducting tissues, smooth muscle and endothelial cells that exhibited myocardial contraction and action potentials. The heart organoids exhibit ultrastructural, histochemical and gene expression characteristics of considerable similarity to those of developmental hearts in vivo. Our results demonstrate that this method not only provides a biomimetic model of the developing heart-like structure with simplified differentiation protocol, but also represents a promising research tool with a broad range of applications, including drug testing.

Our understanding of the development of the heart has been limited by a lack of in vitro cellular models. Here, the authors treat mouse embryonic stem cell-derived embryoid bodies with laminin-entactin (to mimic the developing microenvironment) and FGF4 to form heart organoids, with atrial and ventricular-like parts.

FRI0227 A USABILITY SURVEY OF WRIST MOUNTED DISPOSABLE HEAT PAD ON RAYNAUD’S PHENOMENON IN PATIENTS WITH CONNECTIVE TISSUE DISEASES

Background:

For patients with connective tissue diseases (CTD), vasodilators are used to treat Raynaud’s phenomenon (RP), they are difficult to control only by medication. Although physicians recommend the use of a portable handwarmer or gloves to patients with CTD presenting with RP, sustained heat-retention effects cannot be obtained from them because the patients’ daily life-related activities prevent their continued use. Since the wrist mounted disposable heat pad maintains the degrees of freedom of the hands and fingers and can remain usable during the daily activities, we considered this heat pad as a useful and highly practical heating method for CTD patients presenting with RP.

Objectives:

To investigate the usability and changes in symptoms resulting from the use of the wrist mounted disposable heat pad in CTD patients presenting with RP.

Methods:

Subjects were 23 outpatients with CTD presenting with RP (23 females; mean age 62.6 years; mean duration following the onset of RP 10.3 years; 12 systemic sclerosis, 5 mixed connective tissue disease, 5 Sjögren’s syndrome, and 1 systemic lupus erythematosus) who had used the wrist mounted disposable heat pad (put the pad in a specifically designed holder and wrap it around wrist joint (max. temperature 42 degrees Celsius, heat-retention time 6 hours)). We investigated through interviews with them the use situations, usability, and changes in RP. During their using the heat pad, medication and daily life-related precautions against RP continued to be implemented as before.

Results:

Many patients had no knowledge of the heat pad (n=17, 73.9%). The most common wearing time of the heat pad was 5–6 hours (n=8, 34.8%). As for scenes of wearing the heat pad, patients who wore the pad when being out of the home accounted for the highest proportion (n=16, 69.6%), and as follows: at home (n=6, 26.1%), during kitchen work (n=3, 13.0%), and during housework (n=2, 8.7%). 17 patients (73.9%) replied that usability was “good”, and 18 (78.3%) replied that usability was “better” compared with conventional measures. Moreover, many patients (n=16, 69.6%) replied that RP and associated symptoms had become reduced or alleviated. No patients replied that RP and associated symptoms had become exacerbated or severer. In terms of advantages of using the heat pad, patients who replied that the site on which the pad was mounted was felt to be warm accounted for the highest proportion (n=8, 34.8%), and those who replied that sites other than where the pad was mounted (such as fingertips, hands, and arms) were also warmed accounted for virtually the same proportion (n=7, 30.4%). Over 60% of the patients (n=14, 60.9%) replied that symptoms associated with RP (skin color, cold sensation, and pain) had become reduced or disappeared. In terms of disadvantages of using the heat pad, patients who replied that it was bothersome to use the pad accounted for the highest proportion while other patients made replies referring to cost and bad appearance. No significant accident occurred and as many as 17 patients (73.9%) replied that they would like to continue to use the heat pad in the future.

Conclusion:

There have been few reports evaluating the usefulness of a heat pad for RP. The wrist mounted disposable heat pad was thought to be a heating method having the potential to achieve high levels of usability and practicality on CTD patients presenting with RP. Given that the heat pad alleviated RP or caused sites other than where the pad was mounted to be felt warm even though it did not directly heat the hands and fingers, the pad seemed to have usefulness attributed to the heating of the wrist. Although the heat pad seems to be an excellent method for addressing RP in patients’ daily lives, we hope that this heat pad will be evaluated on a larger number of patients with the addition of objective indices.

References:

[1]Koscheyev VS, et al. Aviat Space Environ Med. 72: 713-719, 2001.

Disclosure of Interests:

Naoto Azuma: None declared, Tetsuya Furukawa: None declared, Yoshihito Shima Grant/research support from: Endowed chair funded by/accepted a researcher from Kirikai Chemical and Kobayashi Pharmaceutical., Kiyoshi Matsui Grant/research support from: Asahi Kasei Pharma, Astellas Pharma (research grants), Speakers bureau: Bristol-Myers Squibb (lecture fees)

FRI0113 THE BASELINE SOLUBLE GP130 IS ASSOCIATED WITH THE RESPONSE OF RHEUMATOID ARTHRITIS PATIENTS TO SARILUMAB

Background:

IL-6 contributes significantly to the chronic inflammatory process of rheumatoid arthritis (RA). Sarilumab (SRL), a human anti-human IL-6 receptor alpha monoclonal antibody that blocks the signaling originated by the IL-6/IL-6R complex like tocilizumab,is an effective treatment. However, predictors of the response to sarilumab are still required.

Objectives:

We aimed to combine IL-6, soluble IL-6R (sIL-6R) and gp130 (sgp130) levels to identify groups of sarilumab responses.

Methods:

This research is a retrospective study. a total of 32 RA patients with SRL therapy in our department from February 1 in 2018 to December 31 in 2019 were included. Serum and clinical data from 32 RA patients were collected before treatment and until the last visit. Follow-up period was up to one year after starting SRL treatment. Serum were tested for IL-6 (Human IL-6 Quantikine ELISA Kit, R&D systems), sIL-6R (Human soluble IL-6R alpha Quantikine ELISA Kit, R&D systems) and sgp130 (Human soluble gp130 Quantikine ELISA Kit, R&D systems), using specific ELISAs according to the manufacturer’s instructions. Hierarchical cluster analysis (JMP14.3.0) was used to establish the relationship between IL-6, sIL-6R and sgp130. We evaluated the efficacy of SRL treatment on the last visit using European League Against Rheumatism (EULAR) response criteria in the groups of patients. The other statistical analyses were performed with EZR 1.41, and p Values less than 0.05 were considered significant.

Results:

The median age of patients was 70.5 (IQR: 66.5-74.3) years and the median of disease duration was 7.3 (1.7-15.3) years. Nine (28.1%) patients were biologics and Jakinibs naive. the median follow-up periods were 24 (12-26) weeks. The baseline DAS28 was median 4.39 (3.77 - 5.43), and CDAI was 21.1 (11.7-29.5). When comparing responders and non-responders, there were no significant differences in any of the baseline parameters and cytokines. Four statistical significant clusters of RA patients (i.e., Group1, Group2, Group3 and tocilizumab use group before SRL) were defined by serum concentrations of IL-6, sIL-6R and spg130 at baseline. The levels of IL-6 expressed as median in Group1 patients were 25.6 (14.4–72.2) pg/ml, in Group2 5.9 (3.3–11.3) pg/ml, and in Group3 70.2 (45.4–86.1) pg/ml (p < 0.002, significant difference only between Group2 and Group3). The levels of sIL-6R expressed as median in Group1 patients were 38.7 (34.7-45.1) ng/ml, in Group2 35.1 (24.8-41.9) ng/ml, and in Group3 35.7 (34.2-39.8) ng/ml (p = 0.5477). The levels of sgp130 expressed as median in Group1 patients were 272.6 (263.0-277.2) ng/ml, in Group2 223.1 (221.0-228.0) ng/ml, and in Group3 204.6 (192.0-207.6) ng/ml (p < 0.00003, significant difference between the three groups respectively). There were no significant differences in any of the baseline clinical features and laboratory findings between the three groups. Out of the 8 patients in Group1 had a good or moderate response to SRL. Conversely, the percentage of patients with no response to SRL was higher in Group3 than in Group1 and Group2.

Conclusion:

RA patients could be easily stratified prior to the rapeutic intervention with sgp130 related to the IL-6 signal reguration. Group1 patients, who had the best response to SRL, had the highest level of sgp130.

Table 1.

Comparison of baseline serum IL-6, sIL-6R and sgp130 of each groups of patients

TCZ use before SRLGroup 1Group 2Group 3P valuen=3N=9N=8N=9IL-6,pg/mL69.8,77.6,592.6Median[IQR]25.6[14.4-72.2]5.9[3.3-11.3]70.2[45.4-86.1]<0.002csIL-6R,ng/mL390.5,413.2,481.7Median[IQR]38.7[34.7-45.1]35.1[24.8-41.9]35.7[34.2-39.8]0.547sgp130,ng/mL205.6,219.2,239.8Median[IQR]273[263-277]223[221-228]205[192-208]<0.001abc

*a, b and c mean that statically significant difference between subgroups as a: group1 vs. 2, b: group 1 vs. 3, c: group 2 vs. 3.

Disclosure of Interests:

Takahiro Yoshikawa: None declared, Tetsuya Furukawa: None declared, Masao Tamura: None declared, Teppei Hashimoto: None declared, Mai Morimoto: None declared, Naoto Azuma: None declared, Kiyoshi Matsui Grant/research support from: Asahi Kasei Pharma, Astellas Pharma (research grants), Speakers bureau: Bristol-Myers Squibb (lecture fees)

g Factor of the ^{99}Zr (7/2^{+}) Isomer: Monopole Evolution in the Shape-Coexisting Region

The gyromagnetic factor of the low-lying E=251.96(9)  keV isomeric state of the nucleus ^{99}Zr was measured using the time-dependent perturbed angular distribution technique. This level is assigned a spin and parity of J^{π}=7/2^{+}, with a half-life of T_{1/2}=336(5)  ns. The isomer was produced and spin aligned via the abrasion-fission of a ^{238}U primary beam at RIKEN RIBF. A magnetic moment |μ|=2.31(14)μ_{N} was deduced showing that this isomer is not single particle in nature. A comparison of the experimental values with interacting boson-fermion model IBFM-1 results shows that this state is strongly mixed with a main νd_{5/2} composition. Furthermore, it was found that monopole single-particle evolution changes significantly with the appearance of collective modes, likely due to type-II shell evolution.

Coordinated demethylation of H3K9 and H3K27 is required for rapid inflammatory responses of endothelial cells

Histone H3 lysine-9 di-methylation (H3K9me2) and lysine-27 tri-methylation (H3K27me3) are linked to repression of gene expression, but the functions of repressive histone methylation dynamics during inflammatory responses remain enigmatic. Here, we report that lysine demethylases 7A (KDM7A) and 6A (UTX) play crucial roles in tumor necrosis factor (TNF)-α signaling in endothelial cells (ECs), where they are regulated by a novel TNF-α-responsive microRNA, miR-3679-5p. TNF-α rapidly induces co-occupancy of KDM7A and UTX at nuclear factor kappa-B (NF-κB)-associated elements in human ECs. KDM7A and UTX demethylate H3K9me2 and H3K27me3, respectively, and are both required for activation of NF-κB-dependent inflammatory genes. Chromosome conformation capture-based methods furthermore uncover increased interactions between TNF-α-induced super enhancers at NF-κB-relevant loci, coinciding with KDM7A and UTX recruitments. Simultaneous pharmacological inhibition of KDM7A and UTX significantly reduces leukocyte adhesion in mice, establishing the biological and potential translational relevance of this mechanism. Collectively, these findings suggest that rapid erasure of repressive histone marks by KDM7A and UTX is essential for NF-κB-dependent regulation of genes that control inflammatory responses of ECs.

Mutant KCNJ3 and KCNJ5 Potassium Channels as Novel Molecular Targets in Bradyarrhythmias and Atrial Fibrillation

BACKGROUND

Bradyarrhythmia is a common clinical manifestation. Although the majority of cases are acquired, genetic analysis of families with bradyarrhythmia has identified a growing number of causative gene mutations. Because the only ultimate treatment for symptomatic bradyarrhythmia has been invasive surgical implantation of a pacemaker, the discovery of novel therapeutic molecular targets is necessary to improve prognosis and quality of life.

METHODS

We investigated a family containing 7 individuals with autosomal dominant bradyarrhythmias of sinus node dysfunction, atrial fibrillation with slow ventricular response, and atrioventricular block. To identify the causative mutation, we conducted the family-based whole exome sequencing and genome-wide linkage analysis. We characterized the mutation-related mechanisms based on the pathophysiology in vitro. After generating a transgenic animal model to confirm the human phenotypes of bradyarrhythmia, we also evaluated the efficacy of a newly identified molecular-targeted compound to upregulate heart rate in bradyarrhythmias by using the animal model.

RESULTS

We identified one heterozygous mutation, KCNJ3 c.247A>C, p.N83H, as a novel cause of hereditary bradyarrhythmias in this family. KCNJ3 encodes the inwardly rectifying potassium channel Kir3.1, which combines with Kir3.4 (encoded by KCNJ5) to form the acetylcholine-activated potassium channel ( I_KACh channel) with specific expression in the atrium. An additional study using a genome cohort of 2185 patients with sporadic atrial fibrillation revealed another 5 rare mutations in KCNJ3 and KCNJ5, suggesting the relevance of both genes to these arrhythmias. Cellular electrophysiological studies revealed that the KCNJ3 p.N83H mutation caused a gain of I_KACh channel function by increasing the basal current, even in the absence of m₂ muscarinic receptor stimulation. We generated transgenic zebrafish expressing mutant human KCNJ3 in the atrium specifically. It is interesting to note that the selective I_KACh channel blocker NIP-151 repressed the increased current and improved bradyarrhythmia phenotypes in the mutant zebrafish.

CONCLUSIONS

The I_KACh channel is associated with the pathophysiology of bradyarrhythmia and atrial fibrillation, and the mutant I_KACh channel ( KCNJ3 p.N83H) can be effectively inhibited by NIP-151, a selective I_KACh channel blocker. Thus, the I_KACh channel might be considered to be a suitable pharmacological target for patients who have bradyarrhythmia with a gain-of-function mutation in the I_KACh channel.

Perturbation of the titin/MURF1 signaling complex is associated with hypertrophic cardiomyopathy in a fish model and in human patients

Hypertrophic cardiomyopathy (HCM) is a hereditary disease characterized by cardiac hypertrophy with diastolic dysfunction. Gene mutations causing HCM have been found in about half of HCM patients, while the genetic etiology and pathogenesis remain unknown for many cases of HCM. To identify novel mechanisms underlying HCM pathogenesis, we generated a cardiovascular-mutant medaka fish, non-spring heart (nsh), which showed diastolic dysfunction and hypertrophic myocardium. The nsh homozygotes had fewer myofibrils, disrupted sarcomeres and expressed pathologically stiffer titin isoforms. In addition, the nsh heterozygotes showed M-line disassembly that is similar to the pathological changes found in HCM. Positional cloning revealed a missense mutation in an immunoglobulin (Ig) domain located in the M-line–A-band transition zone of titin. Screening of mutations in 96 unrelated patients with familial HCM, who had no previously implicated mutations in known sarcomeric gene candidates, identified two mutations in Ig domains close to the M-line region of titin. In vitro studies revealed that the mutations found both in medaka fish and in familial HCM increased binding of titin to muscle-specific ring finger protein 1 (MURF1) and enhanced titin degradation by ubiquitination. These findings implicate an impaired interaction between titin and MURF1 as a novel mechanism underlying the pathogenesis of HCM.

Summary: The authors identified and characterized a medaka mutation in titin that leads to a phenotype similar to hypertrophic cardiomyopathy. Similar mutations were also observed in human patients.

Pathway analysis with genome-wide association study (GWAS) data detected the association of atrial fibrillation with the mTOR signaling pathway

Background

Genome-wide association studies (GWAS) have identified numerous loci associated with diseases and traits. However, the elucidation of disease mechanisms followed by drug development has remained a challenge owing to complex gene interactions. We performed pathway analysis with MAGENTA (Meta-Analysis Geneset Enrichment of variaNT Associations) to clarify the pathways in genetic background of AF.

Methods

The existing GWAS data were analyzed using MAGENTA. A microarray analysis was then performed for the identified pathways with human atrial tissues, followed by Gene-Set Enrichment Analysis (GSEA).

Results

MAGENTA identified two novel candidate pathways for AF pathogenesis, the CTCF (CCCTC-binding factor, p = 1.00 × 10⁻⁴, FDR q = 1.64 × 10⁻²) and mTOR pathways (mammalian target of rapamycin, p = 3.00 × 10⁻⁴, FDR q = 3.13 × 10⁻²). The microarray analysis with human atrial tissue using the GSEA indicated that the mTOR pathway was suppressed in AF cases compared with non-AF cases, validating the MAGENTA results, but not CTCF pathway.

Conclusions

MAGENTA identified a novel pathway, mTOR, followed by GSEA with human atrial tissue samples. mTOR pathway is a key interface that adapts the change of environments by pressure overload and metabolic perturbation. Our results indicate that the MTOR pathway is involved in the pathogenesis of AF, although the details of the basic mechanism remain unknown and further analysis for causal-relationship of mTOR pathway to AF is required. CTCF pathway is essential for construction of chromatin structure and transcriptional process. The gene-set components of CTCF overlap with those of mTOR in Biocarta.

Networking analysis on superior vena cava arrhythmogenicity in atrial fibrillation

Atrial fibrillation (AF) can be initiated from arrhythmogenic foci within the muscular sleeves that extend not only into the pulmonary veins but also into both vena cavae. Patients with SVC-derived AF have the common clinical and genetic risk factors. Bayesian network analysis is a probabilistic model in which a qualitative dependency relationship among random variables is represented by a graph structure and a quantitative relationship between individual variables is expressed by a conditional probability.

We used data of meta-analysis of 2170 AF patients with and without SVC arrhythmogenicity in the previous article. Bayesian Networking analysis was performed using the software “bnlearn”. Using the clinical and genetic factors associated with SVC arrhythmogenicity in the previous article, we investigated a Bayesian networking structure to determine the probabilitic causation of variants to clinical parameters and found that the rate of recurrence depended on SVC arrhythmogenicity and LA diameter, and that SVC arrhythmogenicity was conditionally dependent on gender, body mass index, and genetic risk score. We found the possibility of prediction model generated from three factors. Receiver-operation characteristic analysis showed the area under the curve was 0.84.

Using the clinical/genetic factors associated with SVC arrhythmogenicity through the previous meta-analysis of over 2000 patients, Bayesian networking analysis indicated the probabilistic causation of SVC arrhythmogenicity and associated clinical/genetic factors.

Radiative cooling of cationic carbon clusters, CN+, N = 8, 10, 13-16

The radiative cooling of highly excited carbon cluster cations of sizes N = 8, 10, 13-16 has been studied in an electrostatic storage ring. The cooling rate constants vary with cluster size from a maximum at N = 8 of 2.6 × 10⁴ s^-1 and a minimum at N = 13 of 4.4 × 10³ s^-1. The high rates indicate that photon emission takes place from electronically excited ions, providing a strong stabilizing cooling of the molecules.

Important cardiac transcription factor genes are accompanied by bidirectional long non-coding RNAs

Background

Heart development is a relatively fragile process in which many transcription factor genes show dose-sensitive characteristics such as haploinsufficiency and lower penetrance. Despite efforts to unravel the genetic mechanism for overcoming the fragility under normal conditions, our understanding still remains in its infancy. Recent studies on the regulatory mechanisms governing gene expression in mammals have revealed that long non-coding RNAs (lncRNAs) are important modulators at the transcriptional and translational levels. Based on the hypothesis that lncRNAs also play important roles in mouse heart development, we attempted to comprehensively identify lncRNAs by comparing the embryonic and adult mouse heart and brain.

Results

We have identified spliced lncRNAs that are expressed during development and found that lncRNAs that are expressed in the heart but not in the brain are located close to genes that are important for heart development. Furthermore, we found that many important cardiac transcription factor genes are located in close proximity to lncRNAs. Importantly, many of the lncRNAs are divergently transcribed from the promoter of these genes. Since the lncRNA divergently transcribed from Tbx5 is highly evolutionarily conserved, we focused on and analyzed the transcript. We found that this lncRNA exhibits a different expression pattern than that of Tbx5, and knockdown of this lncRNA leads to embryonic lethality.

Conclusion

These results suggest that spliced lncRNAs, particularly bidirectional lncRNAs, are essential regulators of mouse heart development, potentially through the regulation of neighboring transcription factor genes.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5233-5) contains supplementary material, which is available to authorized users.

Arrhythmic hazard map for a 3D whole-ventricle model under multiple ion channel block

Background and Purpose

To date, proposed in silico models for preclinical cardiac safety testing are limited in their predictability and usability. We previously reported a multi‐scale heart simulation that accurately predicts arrhythmogenic risk for benchmark drugs.

Experimental Approach

We created a comprehensive hazard map of drug‐induced arrhythmia based on the electrocardiogram (ECG) waveforms simulated under wide range of drug effects using the multi‐scale heart simulator described here, implemented with cell models of human cardiac electrophysiology.

Key Results

A total of 9075 electrocardiograms constitute the five‐dimensional hazard map, with coordinates representing the extent of the block of each of the five ionic currents (rapid delayed rectifier potassium current (I_Kr), fast (I_Na) and late (I_Na,L) components of the sodium current, L‐type calcium current (I_Ca,L) and slow delayed rectifier current (I_Ks)), involved in arrhythmogenesis. Results of the evaluation of arrhythmogenic risk based on this hazard map agreed well with the risk assessments reported in the literature. ECG databases also suggested that the interval between the J‐point and the T‐wave peak is a superior index of arrhythmogenicity when compared to the QT interval due to its ability to characterize the multi‐channel effects compared with QT interval.

Conclusion and Implications

Because concentration‐dependent effects on electrocardiograms of any drug can be traced on this map based on in vitro current assay data, its arrhythmogenic risk can be evaluated without performing costly and potentially risky human electrophysiological assays. Hence, the map serves as a novel tool for use in pharmaceutical research and development.

Spatial measurement in rotating magnetic field plasma acceleration method by using two-dimensional scanning instrument and thrust stand

A two-dimensional scanning probe instrument has been developed to survey spatial plasma characteristics in our electrodeless plasma acceleration schemes. In particular, diagnostics of plasma parameters, e.g., plasma density, temperature, velocity, and excited magnetic field, are essential for elucidating physical phenomena since we have been concentrating on next generation plasma propulsion methods, e.g., Rotating Magnetic Field plasma acceleration method, by characterizing the plasma performance. Moreover, in order to estimate the thrust performance in our experimental scheme, we have also mounted a thrust stand, which has a target type, on this movable instrument, and scanned the axial profile of the thrust performance in the presence of the external magnetic field generated by using permanent magnets, so as to investigate the plasma captured in a stand area, considering the divergent field lines in the downstream region of a generation antenna. In this paper, we will introduce the novel measurement instrument and describe how to measure these parameters.

Electrophysiological Assessment of Murine Atria with High-Resolution Optical Mapping

Recent genome-wide association studies targeting atrial fibrillation (AF) have indicated a strong association between the genotype and electrophysiological phenotype in the atria. That encourages us to utilize a genetically-engineered mouse model to elucidate the mechanism of AF. However, it is difficult to evaluate the electrophysiological properties in murine atria due to their small size. This protocol describes the electrophysiological evaluation of atria using an optical mapping system with a high temporal and spatial resolution in Langendorff perfused murine hearts. The optical mapping system is assembled with dual high-speed complementary metal oxide semiconductor cameras and high magnification objective lenses, to detect the fluorescence of a voltage-sensitive dye and Ca²⁺ indicator. To focus on the assessment of murine atria, optical mapping is performed with an area of 2 mm × 2 mm or 10 mm x 10 mm, with a 100 × 100 resolution (20 µm/pixel or 100 µm/pixel) and sampling rate of up to 10 kHz (0.1 ms) at maximum. A 1-French size quadripolar electrode pacing catheter is placed into the right atrium through the superior vena cava avoiding any mechanical damage to the atrium, and pacing stimulation is delivered through the catheter. An electrophysiological study is performed with programmed stimulation including constant pacing, burst pacing, and up to triple extrastimuli pacing. Under a spontaneous or pacing rhythm, the optical mapping recorded the action potential duration, activation map, conduction velocity, and Ca²⁺ transient individually in the right and left atria. In addition, the programmed stimulation also determines the inducibility of atrial tachyarrhythmias. Precise activation mapping is performed to identify the propagation of the excitation in the atrium during an induced atrial tachyarrhythmia. Optical mapping with a specialized setting enables a thorough electrophysiological evaluation of the atrium in murine pathological models.

Coherent anti-Stokes Raman scattering rigid endoscope toward robot-assisted surgery

Label-free visualization of nerves and nervous plexuses will improve the preservation of neurological functions in nerve-sparing robot-assisted surgery. We have developed a coherent anti-Stokes Raman scattering (CARS) rigid endoscope to distinguish nerves from other tissues during surgery. The developed endoscope, which has a tube with a diameter of 12 mm and a length of 270 mm, achieved 0.91% image distortion and 8.6% non-uniformity of CARS intensity in the whole field of view (650 μm diameter). We demonstrated CARS imaging of a rat sciatic nerve and visualization of the fine structure of nerve fibers.

Chromosome 4q25 variants and recurrence after second-generation cryoballoon ablation in patients with paroxysmal atrial fibrillation

BACKGROUND

Chromosome 4q25 single-nucleotide polymorphisms (SNPs) are associated with atrial fibrillation (AF) recurrence after radiofrequency catheter ablation, however the underlying mechanism is unknown. Pulmonary vein (PV) reconnections are common post-radiofrequency ablation. We explored the pre-procedural parameters, including AF susceptibility SNPs, predicting the response to PV isolation (PVI) using second-generation cryoballoons.

METHODS

One hundred fifty-seven paroxysmal AF patients undergoing PVI using second-generation cryoballoons and genetic testing were enrolled. The top 6 AF-associated Japanese ancestry SNPs were evaluated. Fourteen-day consecutive monitoring was performed to detect AF recurrences.

RESULTS

Early recurrence of AF (ERAF) was detected in 74(47.1%) patients, and the AF-free survival at 12-months after single procedures was 72.1%. Cox's proportional models determined that higher pro-BNP values (hazard ratio [HR]=1.001; 95% confidence interval [CI]=1.000-1.001; p=0.003) and the rs1906617 risk allele (HR=2.440; 95% CI=1.062-5.605; p=0.035) were independently associated with ERAFs, and the rs1906617 risk allele (HR=4.339; 95% CI=1.044-18.028; p=0.043) was the sole factor significantly associated with AF recurrence. Second procedures were performed in 41 patients a median of 6.0[5.0-9.5] months later, and 42/162(25.9%) PVs were reconnected. Reconnections were similarly observed in rs1906617 risk allele carriers and wild-type patients. Risk allele carriers at rs1906617 were more likely to have non-PV foci, but did not reach statistical significance (10/35 vs. 0/6, p=0.132).

CONCLUSIONS

AF risk alleles on chromosome 4q25 modulated the risk of AF recurrence after PVI using second-generation cryoballoons in patients with paroxysmal AF. Our study results suggested that non-PV foci might be the more likely mechanism of a high AF recurrence in chromosome 4q25 variant carriers.