Intravenous iron infusion ameliorates anaemia and protein-losing enteropathy in patients after Fontan surgery: case series

Protein-losing enteropathy is a severe complication of Fontan surgery and is associated with anaemia. Few studies have reported on the efficacy of an intravenous iron infusion for treating protein-losing enteropathy and low albuminemia after Fontan surgery. Herein, we present two cases of female patients who suffered from protein-losing enteropathy and low albuminemia following Fontan surgery, both of whom improved after an intravenous iron infusion.

Calmodulinopathy in Japanese Children - Their Cardiac Phenotypes Are Severe and Show Early Onset in Fetal Life and Infancy

BACKGROUND

Cardiac calmodulinopathy, characterized by a life-threatening arrhythmia and sudden death in the young, is extremely rare and caused by genes encoding calmodulin, namely calmodulin 1 (CALM1), CALM2, and CALM3.Methods and Results: We screened 195 symptomatic children (age 0-12 years) who were suspected of inherited arrhythmias for 48 candidate genes, using a next-generation sequencer. Ten probands were identified as carrying variants in any of CALM1-3 (5%; median age 5 years), who were initially diagnosed with long QT syndrome (LQTS; n=5), catecholaminergic polymorphic ventricular tachycardia (CPVT; n=3), and overlap syndrome (n=2). Two probands harbored a CALM1 variant and 8 probands harbored 6 CALM2 variants. There were 4 clinical phenotypes: (1) documented lethal arrhythmic events (LAEs): 4 carriers of N98S in CALM1 or CALM2; (2) suspected LAEs: CALM2 p.D96G and D132G carriers experienced syncope and transient cardiopulmonary arrest under emotional stimulation; (3) critical cardiac complication: CALM2 p.D96V and p.E141K carriers showed severe cardiac dysfunction with QTc prolongation; and (4) neurological and developmental disorders: 2 carriers of CALM2 p.E46K showed cardiac phenotypes of CPVT. Beta-blocker therapy was effective in all cases except cardiac dysfunction, especially in combination with flecainide (CPVT-like phenotype) and mexiletine (LQTS-like).

CONCLUSIONS

Calmodulinopathy patients presented severe cardiac features, and their onset of LAEs was earlier in life, requiring diagnosis and treatment at the earliest age possible.

Utility of the Angle between the Right Aortic Arch and First Branch for Detecting Double Aortic Arch via Fetal Echocardiography

INTRODUCTION

The presence of a double aortic arch (DAA) is manifested by compressive symptoms, requiring surgery. DAA cases are classified as either complete or incomplete type. DAA and a right aortic arch with mirror image branching (mRAA) have a similar configuration to the first branch artery. The first branch of the mRAA is the left brachiocephalic artery, which appears to be the same as that of an incomplete DAA due to blood flow interruption. The present retrospective study aimed to evaluate the differences between DAA and mRAA by fetal echocardiography.

METHODS

This single retrospective cohort study included all patients diagnosed with complete DAA, incomplete DAA, or mRAA at our facility between 2010 and 2022. The patients were diagnosed with complete DAA, incomplete DAA, or mRAA after birth and remaining fetal echocardiograms. The patients were divided into the DAA (complete DAA: n = 4, incomplete DAA: n = 3) and mRAA (n = 4) groups. The following three outcomes were compared: (1) angle between the right aortic arch and first branch (RF angle), (2) ratio of height to width of the region bounded by the aortic arch, first branch of the aortic arch, and descending aorta, and (3) maximum tracheal diameter on a three-vessel trachea view.

RESULTS

The incomplete DAA cases were difficult to diagnose via fetal echocardiography. On fetal echocardiography, the RF angle was significantly steeper in the DAA group than in the mRAA group (median 57° [36°-69°] vs. 75° [62°-94°]; p < 0.05). The DAA and RAA groups showed no significant differences in the ratio of height to width of the region bounded by the aortic arch, first branch of the aortic arch, and descending aorta (median 0.57 [0.17-0.68] vs. 0.73 [0.56-1.0]) and maximum tracheal diameter (median 2.5 [1.4-3.3] vs. 3.2 [2.8-3.5] mm). The cut-off value for the presence of DAA was an RF angle <71°.

CONCLUSION

The DAA group (complete and incomplete DAA) had a significantly steeper RF angle than the mRAA group. Therefore, RF angle measurement could improve the fetal diagnosis and postnatal prognosis of DAA.

Successful bailout stenting for critical aortic coarctation in a premature baby weighing 590 g

Severe aortic coarctation (CoA) is a critical congenital heart disease that requires surgery as the first-line treatment in neonates. However, in very small premature infants, aortic arch repair has a relatively high mortality and morbidity rate. Bailout stenting is an alternative method that can be performed safely and effectively with low morbidity.We present a case of severe CoA in a premature baby, a monochorionic twin with selective intrauterine growth restriction. The patient was born at 31 weeks of gestation with a birth weight of 570 g. Seven days following her birth, she experienced anuria due to critical neonatal isthmic CoA. She underwent a stent implantation procedure at term neonatal, weighing 590 g. She had good dilatation of the coarcted segment with no complications. Follow-up at infancy showed no CoA recurrence. This is the world's smallest case of stenting for CoA.

Utility of novel echocardiographic measurements to improve prenatal diagnosis of coarctation of the aorta

Prenatal recognition of coarctation of the aorta (CoA) may improve neonatal survival and reduce morbidity. However, prenatal diagnosis of CoA remains challenging, with relatively high false-positive and false-negative rates. This study aimed to identify a novel formula based on fetal echocardiographic measures to predict prenatal identification of CoA. A retrospective comparison on the echocardiographic evaluation of 30 patients with suspected CoA between May 2016 and April 2021 was performed. The patients were divided into a postnatal surgical intervention group (n = 13) and a non-intervention group (n = 17). The measurements that showed significant differences were aortic isthmus diameter Z-score (p < 0.001), ductus arteriosus diameter/aortic isthmus diameter (p < 0.001), and distal aortic arch (DA) index (p < 0.001). In the receiver operating characteristic curves analysis, the DA index was the largest with an area under the curve of 0.941 and a cutoff value of 1.28, with a sensitivity of 85% and a specificity of 94%. Measurement of the DA index improved the diagnostic rate of fetal CoA and a DA index ≧ 1.28 indicated fetal CoA cases requiring surgical intervention.

Reopening of ductus arteriosus in idiopathic premature constriction or closure of ductus arteriosus: A case series

BACKGROUND

There is no consensus on managing pregnancy when the fetus is diagnosed with idiopathic premature constriction or closure of the ductus arteriosus (PCDA). Knowing whether the ductus reopens is valuable information for managing idiopathic PCDA. We conducted a case-series study to investigate the natural perinatal course of idiopathic PCDA and examined factors associated with ductal reopening.

METHODS

We retrospectively collected information about the perinatal course and echocardiographic findings at our institution, which, on principle, does not determine delivery timing based on fetal echocardiographic results. We also examined perinatal factors related to the reopening of the ductus arteriosus.

RESULTS

Thirteen cases of idiopathic PCDA were included in the analysis. The ductus reopened in 38% of cases. Among cases diagnosed in <  37 weeks of gestation, 71% reopened, which was confirmed seven days after diagnosis (interquartile range 4-7). Diagnosis earlier in gestation was associated with ductal reopening (p = 0.006). Two cases (15%) developed persistent pulmonary hypertension. No fetal hydrops or death occurred.

CONCLUSIONS

The ductus is likely to reopen when prenatally diagnosed before 37 weeks gestation. There were no complications due to our pregnancy management policy. In idiopathic PCDA, especially if the prenatal diagnosis is made before 37 weeks of gestational age, continuing the pregnancy with careful monitoring of the fetus's well-being is recommended.

Novel Calmodulin Variant p.E46K Associated With Severe Catecholaminergic Polymorphic Ventricular Tachycardia Produces Robust Arrhythmogenicity in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

BACKGROUND

CaM (calmodulin) is a ubiquitously expressed, multifunctional Ca²⁺ sensor protein that regulates numerous proteins. Recently, CaM missense variants have been identified in patients with malignant inherited arrhythmias, such as long QT syndrome and catecholaminergic polymorphic ventricular tachycardia (CPVT). However, the exact mechanism of CaM-related CPVT in human cardiomyocytes remains unclear. In this study, we sought to investigate the arrhythmogenic mechanism of CPVT caused by a novel variant using human induced pluripotent stem cell (iPSC) models and biochemical assays.

METHODS

We generated iPSCs from a patient with CPVT bearing CALM2 p.E46K. As comparisons, we used 2 control lines including an isogenic line, and another iPSC line from a patient with long QT syndrome bearing CALM2 p.N98S (also reported in CPVT). Electrophysiological properties were investigated using iPSC-cardiomyocytes. We further examined the RyR2 (ryanodine receptor 2) and Ca²⁺ affinities of CaM using recombinant proteins.

RESULTS

We identified a novel de novo heterozygous variant, CALM2 p.E46K, in 2 unrelated patients with CPVT accompanied by neurodevelopmental disorders. The E46K-cardiomyocytes exhibited more frequent abnormal electrical excitations and Ca²⁺ waves than the other lines in association with increased Ca²⁺ leakage from the sarcoplasmic reticulum via RyR2. Furthermore, the [³H]ryanodine binding assay revealed that E46K-CaM facilitated RyR2 function especially by activating at low [Ca²⁺] levels. The real-time CaM-RyR2 binding analysis demonstrated that E46K-CaM had a 10-fold increased RyR2 binding affinity compared with wild-type CaM which may account for the dominant effect of the mutant CaM. Additionally, the E46K-CaM did not affect CaM-Ca²⁺ binding or L-type calcium channel function. Finally, antiarrhythmic agents, nadolol and flecainide, suppressed abnormal Ca²⁺ waves in E46K-cardiomyocytes.

CONCLUSIONS

We, for the first time, established a CaM-related CPVT iPSC-CM model which recapitulated severe arrhythmogenic features resulting from E46K-CaM dominantly binding and facilitating RyR2. In addition, the findings in iPSC-based drug testing will contribute to precision medicine.

Osteoarthritic changes in the knees of recently retired male professional footballers: a pilot study

Background

Knee osteoarthritis (OA) is common amongst retired male professional footballers. There is limited understanding with respect to the interplay between imaging findings, clinical presentation and patient-reported outcome measures (PROMs) in retired professional footballers with knee OA.

Objectives

This pilot study aimed to evaluate the extent of radiological and clinical knee OA in a cohort of retired male professional footballers, and to explore the relationship between these findings and knee-related PROMs.

Methods

Fifteen retired male professional footballers underwent knee radiographs and were surveyed on their history of clinical OA, severe knee injury and previous knee surgery. The Knee Injury and Osteoarthritis Outcome Score Physical Function Short Form (KOOS-PS) and the Patient-Reported Outcomes Measurement Information System Global Health (PROMIS-GH) were used to assess health outcomes, such as level of function and pain.

Results

Radiological knee OA was diagnosed in six out of 15 participants. Seven of the participants had a clinical diagnosis of knee OA. Evidence of clinical and radiological OA was present amongst four participants. Radiological knee OA and clinical OA was significantly associated with a history of severe knee injury and previous knee surgery. Low correlations (ρ<-0.40) were found between knee OA severity and knee-related PROMs. Moderate correlation (ρ=-0.65) was found between clinical knee OA and KOOS-SP.

Conclusion

Clinical knee OA correlates with PROMs amongst retired professional footballers but radiological OA does not. Further studies are required to understand the relationship between imaging findings, clinical presentation and PROMs amongst retired professional footballers with knee OA.

Control of Heart Rate in Infant and Child Tachyarrhythmia With Reduced Cardiac Function Using Landiolol (HEARTFUL) - Results of a Prospective, Multicenter, Uncontrolled Clinical Study

BACKGROUND

The prospective Control of HEART rate in inFant and child tachyarrhythmia with reduced cardiac function Using Landiolol (HEARTFUL) study investigated the effectiveness and safety of landiolol, a short-acting β₁ selective blocker, in children.Methods and Results: Twenty-five inpatients aged ≥3 months to <15 years who developed supraventricular tachyarrhythmias (atrial fibrillation, atrial flutter, supraventricular tachycardia, and inappropriate sinus tachycardia) were treated with landiolol. The primary endpoint, the percent of patients with a reduction in heart rate ≥20% from the initial rate of tachycardia, or termination of tachycardia at 2 h after starting landiolol, was achieved in 12/25 patients (48.0%; 95% CI 28.4-67.6), which exceeded the predetermined threshold (38.0%). At 2 h after starting landiolol administration, heart rate had decreased by ≥20% in 45.8% (11/24) and recovery to sinus rhythm was achieved in 40.0% (6/15) of the patients. Adverse reactions (ARs) occurred in 24.0% (6/25) of patients, and the study was discontinued in 4.0% (1/25) of the patients; however, none of these ARs were considered serious. The most common AR was hypotension (20.0% [5/25] of patients).

CONCLUSIONS

The HEARTFUL study has demonstrated the efficacy of landiolol, by reducing heart rate or terminating tachycardia, in pediatric patients with supraventricular tachyarrhythmias. Although serious ARs and concerns were not identified in this study, physicians should be always cautious of circulatory collapse due to hypotension.

The role of cellular senescence in aortic dissection

Background

Aortic dissection (AD) is a catastrophic disease that occurs suddenly. The acute mortality is high and those who survived frequently suffer from serious complications such as aneurysm formation and distal ischemia due to progressive destruction of the aortic walls. Currently, no predictor of AD onset is available nor therapeutic intervention to specifically prevent the progressive destruction in AD, because the molecular pathogenesis is largely unknown. Clinical and experimental studies highlighted the importance of inflammation in AD, although the regulatory mechanism of inflammation remains unclear. Recently, we found that cell proliferation precedes the inflammatory response in AD. Because cell proliferation causes cellular senescence that can induce inflammatory response, we hypothesized that cellular senescence participates in AD pathogenesis.

Objective

We investigated if cellular senescence contributes to AD development and progression in mouse AD model.

Methods and results

A mouse AD model was created by continuous infusion of beta-aminopropionitrile and angiotensin II (BAPN+AngII), where AD starts to develop in 3 days and occurs to most of the mice in 14 days accompanied by frequent AD rupture and death. Infusion of BAPN+AngII resulted in the induction of senescence markers Ink4a from day 3 before AD onset and persisted for the 14 days of the observational period.

Cellular senescence, as demonstrated by the expression of senescence-associated beta-galactosidase, was evident in intimal endothelial cells, medial smooth muscle cells, adventitial macrophages and fibroblasts. We examined the role of cellular senescence in AD pathogenesis by oral administration of ABT263 which is known as “senolytics” that eliminates senescent cells. ABT263 treatment reduced the expression of the senescence marker, prevented the death by AD rupture, and ameliorated the severity of AD lesion compared to the vehicle treatment. Transcriptome analysis revealed that ABT treatment suppressed the immune and inflammatory response in AD. Quantitative RT-PCR confirmed that ABT treatment prevented the induction of p21Cip1, interleukin-6, several chemokines and their receptors by 3-day infusion of BAPN+AngII.

Conclusions

These findings demonstrated that senescence of multiple cell types precedes AD development, which is likely to induce the inflammatory response. Elimination of senescent cells effectively prevented AD progression and death. Therefore, cellular senescence represents a potential predictor and a therapeutic target for AD.

Funding Acknowledgement

Type of funding sources: None.

Association Between Deleterious SCN5A Variants and Ventricular Septal Defect in Young Patients With Brugada Syndrome

OBJECTIVES

This study aimed to investigate the clinical characteristics of young patients with Brugada syndrome (BrS) with ventricular septal defect (VSD) and explore their genetic backgrounds.

BACKGROUND

VSD is the most frequently occurring congenital heart disease among children. In contrast, BrS is a rare hereditary disease that is responsible for ventricular fibrillation and sudden cardiac death. Owing to their low incidence, the genetic background and clinical characteristics of patients with BrS with VSD have not been elucidated yet.

METHODS

This study enrolled 36 individuals who were diagnosed with BrS when they were <20 years of age and performed genetic screening for SCN5A. The functional alteration in mutant Na⁺ channels was confirmed by patch clamp technique.

RESULTS

Among the 36 patients with BrS, 5 had been diagnosed with VSD. This study found 14 heterozygous SCN5A variants in 15 unrelated patients. The 5 patients with VSD carried SCN5A variants, including R367S, R535∗, R893C, W1345C, and G1743R. The 3 missense variants (R893C, W1345C, and G1743R) have been proved to reduce peak Na⁺ current to <10%. A functional analysis of SCN5A R367S was performed and the variant was found to be nonfunctional.

CONCLUSIONS

This study identified 5 loss-of-function SCN5A variants in 5 young patients with BrS with VSD. The study hypothesizes that altered blood flow in the right ventricular outflow tract leads to fibrosis and electrophysiological changes, predisposing the patients to earlier clinical presentation of BrS. In patients with VSD and ST-segment elevation in the right precordial leads, BrS should be considered and appropriate screening should be pursued accordingly.

School-based routine screenings of electrocardiograms for the diagnosis of long QT syndrome

Aims

School-based routine screenings of electrocardiograms (ECGs) have been performed upon admission to primary school (PS), junior high school (JHS), and high school (HS) in Japan. Though ECGs with prolonged QT intervals are occasionally found, the role of regular ECG screening tests in identifying long QT syndrome (LQTS) remains to be determined. We investigated the usefulness of the ECG screenings by comparing the results of genetic tests between students who showed QT-prolongation in the screenings and patients with LQTS.

Methods and results

We genetically screened 341 students (106 PS, 173 JHS, and 62 HS). Of these, 230 subjects showed QT-prolongation during regular screenings (S-S group), and the other 111 patients were clinically consulted with suspected LQTS by paediatricians (C-C group). Genotype–phenotype relationships were compared between the two groups. The positive rates in the genetic tests were comparable among the two groups; however, symptomatic subjects were significantly fewer in the S-S group than the C-C group (3% vs. 70%). Compared to the genotype-negative subjects, the positive subjects showed significantly longer QTc (P &lt; 0.0001) and more frequently presented LQTS risk scores with ≥3.5 points (P &lt; 0.0001). Lethal arrhythmic events (LAE) occurred only in the C-C group; 18 subjects experienced LAE and 83% of them were found to carry variant(s) in the LQTS-related genes.

Conclusion

The school-based ECG screenings are effective in identifying young patients with LQTS who require genetic analysis. If individuals are screened at a younger age, we can identify patients at risk earlier and provide preventative treatments.

Colchicine protects against cartilage degeneration by inhibiting MMP13 expression via PLC-γ1 phosphorylation

OBJECTIVE

Low molecular weight compounds that reduce the expression of MMP13 at the mRNA level might serve as disease-modifying osteoarthritis (OA) drugs (DMOADs). The objective of this study was to identify a candidate DMOAD that targets MMP13 expression.

DESIGN

High-throughput screening was performed to identify compounds that suppress inflammatory cytokine-induced MMP13 expression. Ingenuity pathway analysis (IPA) using isobaric tags for relative and absolute quantification (iTRAQ)-based proteomic analysis was conducted to identify signaling pathways related to cytokines. MMP13 expression in chondrocytes was evaluated through RT-qPCR and western blotting analyses. Additionally, 10-week-old mice were subjected to destabilization of the medial meniscus (DMM) surgery to induce OA and were sacrificed 12 weeks post-surgery for pathological examination. OA was evaluated using the OARSI scoring system.

RESULTS

Colchicine was identified as a DMOAD candidate as it inhibited inflammatory cytokine-induced MMP13 expression in vitro, and the colchicine-administered mice with DMM presented significantly lower OARSI scores (adjusted P: 0.0242, mean difference: 1.6, 95% confidence interval (CI) of difference: 0.1651-3.035) and significantly lower synovial membrane inflammation scores (adjusted P: 0.0243, mean difference: 0.6, 95% CI of difference: 0.06158-1.138) than mice with DMM. IPA further revealed that components of the Rho signaling pathways are regulated by cytokines and colchicine. IL-1β and TNF-α activate RAC1 and SRC signals, respectively, leading to the phosphorylation of PLC-γ1 and synergistic induction of MMP13 expression. Most notably, colchicine abrogates inflammatory cytokine-induced phosphorylation of PLC-γ1, leading to the induction of MMP13 expression.

CONCLUSIONS

Colchicine is a potential DMOAD candidate that inhibits MMP13 expression and consequent cartilage degradation by disrupting the SRC/RAC1-phospho-PLCγ1-Ca2+ signaling pathway.

Loss-of-function mutations in cardiac ryanodine receptor channel cause various types of arrhythmias including long QT syndrome

AIMS

Gain-of-function mutations in RYR2, encoding the cardiac ryanodine receptor channel (RyR2), cause catecholaminergic polymorphic ventricular tachycardia (CPVT). Whereas, genotype-phenotype correlations of loss-of-function mutations remains unknown, due to a small number of analysed mutations. In this study, we aimed to investigate their genotype-phenotype correlations in patients with loss-of-function RYR2 mutations.

METHODS AND RESULTS

We performed targeted gene sequencing for 710 probands younger than 16-year-old with inherited primary arrhythmia syndromes (IPAS). RYR2 mutations were identified in 63 probands, and 3 probands displayed clinical features different from CPVT. A proband with p.E4146D developed ventricular fibrillation (VF) and QT prolongation whereas that with p.S4168P showed QT prolongation and bradycardia. Another proband with p.S4938F showed short-coupled variant of torsade de pointes (scTdP). To evaluate the functional alterations in these three mutant RyR2s and p.K4594Q previously reported in a long QT syndrome (LQTS), we measured Ca2+ signals in HEK293 cells and HL-1 cardiomyocytes as well as Ca2+-dependent [3H]ryanodine binding. All mutant RyR2s demonstrated a reduced Ca2+ release, an increased endoplasmic reticulum Ca2+, and a reduced [3H]ryanodine binding, indicating loss-of-functions. In HL-1 cells, the exogenous expression of S4168P and K4594Q reduced amplitude of Ca2+ transients without inducing Ca2+ waves, whereas that of E4146D and S4938F evoked frequent localized Ca2+ waves.

CONCLUSION

Loss-of-function RYR2 mutations may be implicated in various types of arrhythmias including LQTS, VF, and scTdP, depending on alteration of the channel activity. Search of RYR2 mutations in IPAS patients clinically different from CPVT will be a useful strategy to effectively discover loss-of-function RYR2 mutations.

The role of cellular senescence in aortic dissection

Background

Aortic dissection (AD) is a catastrophic disease that occurs suddenly. The acute mortality is high and those who survived frequently suffer from serious complications such as aneurysm formation and distal ischemia due to progressive destruction of the aortic walls. Currently, no reliable predictor is available for AD development and surgical intervention is the only therapeutic option to prevent the fatal events after AD development, because the pathogenesis of AD is largely unknown.

Clinical and experimental studies highlighted the importance of inflammation in AD pathogenesis, although the trigger of inflammation remains unclear. Recently, we found that cell proliferation precedes the inflammatory response in AD. Because cell proliferation triggers cellular senescence and senescent cells secrete of proinflammatory cytokines and matrix metalloproteinases, we hypothesized that cellular senescence may participate in AD pathogenesis.

Objective

We investigated if cellular senescence contributes to AD development and progression in a mouse model of AD.

Methods and results

A mouse AD model was created by continuous infusion of beta-aminopropionitrile and angiotensin II (BAPN+AngII), where AD starts to develop in 3 days and occurs to most of the mice in 14 days accompanied by frequent AD rupture and death. Infusion of BAPN+AngII resulted in the appearance of senescent cells that are positive for senescence-associated beta-galactosidase, and expression of senescence markers Arf and Ink4a in the aortic walls. Appearance of cellular senescence occurred in one day of BAPN+AngII infusion and continued throughout the observational period of 14 days. We examined the role of cellular senescence in AD pathogenesis by oral administration of ABT263 which is known as “senolytics” that eliminates senescent cells. ABT263 treatment reduced the expression of the senescence markers. In the vehicle-treated group, the mortality was 66.7% (12/18), whereas that of ABT263-treated group was 35% (14/20, P&lt;0.05 by log-rank test). The severity of AD, as assessed by the lesion length in vehicle group was33.2±3.1 mm, whereas that in ABT263 group was 24.6±1.8 mm (P&lt;0.05).

Conclusions

These findings demonstrated that cellular senescence precedes AD development, and ABT263 effectively prevented AD progression and death, indicating the involvement of cellular senescence in AD pathogenesis. Therefore, cellular senescence represents a potential predictor and a therapeutic target for AD.

Funding Acknowledgement

Type of funding sources: None.

Involvement of FAK in aortic dissection: potential role in aortic interstitial cells

Background

Aortic dissection (AD) is a fatal disease where the intimomedial layer of the aorta suddenly fail. Although it is widely accepted that hemodynamic stress on the aortic wall triggers its destruction that is further promoted by inflammatory response as exemplified by the infiltration of neutrophils and macrophages, molecular mechanism is unknown for the link of aortic wall stress, inflammation and tissue destruction. In general, mechanical stress to the tissue is converted to the cellular response through the cell adhesion molecules and the activation of focal adhesion kinase (Fak). Although it has been reported that Fak is involved in pathogenesis of aortic aneurysm by promoting migration and activation of macrophages, its role in AD is unknown. We hypothesized that Fak may be involved in AD pathogenesis.

Purpose

We investigated the involvement of Fak in AD pathogenesis, focusing on its role in inflammatory cells.

Methods and results

We created a mouse model of AD by continuous infusion of beta-aminopropionitrile, a collagen crosslink inhibitor, and angiotensin II (BAPN + Ang II). Immunostaining for activated Fak revealed that Fak was not activated in normal aorta, but was activated in the infiltrating inflammatory cells and in interstitial cells of the aortic wall after AD development. We examined the role of Fak by oral administration of PND-1186, a specific Fak inhibitor, in mouse AD model. Vehicle-treated group showed 63.6% mortality, whereas PND-1186-treated group showed 20% mortality (P&lt;0.01, n=20 for each group) in 14 days of the observational period. The aortic arch lesion, the most critical part in AD, was improved from 1.96±0.41 mm in vehicle group to 0.66±0.29 mm in PND group (P&lt;0.05). We next examined the cell type-specific role of Fak in AD by creating macrophage and granulocyte-specific deletion of Fak driven by LysM-Cre and floxed Fak system. Unexpectedly, the genetic deletion of Fak in macrophages and granulocytes had no impact on the mortality nor the severity of AD.

Conclusions

These findings proved that Fak plays a critical role in AD progression and death. Because Fak is dispensable for macrophages and granulocytes, other cell types, possibly aortic wall interstitial cells, may be regulated by Fak in AD pathogenesis. Deciphering the role of Fak would provide the fundamental understanding of AD pathogenesis.

Funding Acknowledgement

Type of funding sources: None.

The role of B cells and IgG in aortic dissection

Background

Aortic dissection (AD) is one of the destructive and fatal aortic diseases, for which molecular pathogenesis is largely unknown. Recent studies have highlighted the importance of inflammatory response in AD. We and others reported that B cells and immunoglobulins participate in pathogenesis of abdominal aortic aneurysm, another form of aortic destructive disease, by promoting inflammatory response. It is not known whether and how B cells participate in AD pathogenesis.

Methods and results

Immunohistochemical staining of human AD tissue revealed that B cells were clustered together with T cells, macrophages and neutrophils at the entry site of AD with medial disruption. B cell cluster was also observed at the site of medial disruption in mouse model of AD that was induced by continuous infusion of beta-aminopropionitrile and angiotensin II (BAPN+AngII). In muMT mouse, which is deficient for B cells and immunoglobulins due to genetic deletion of immunoglobulin heavy chain, BAPN+AngII induced significantly less severe AD compared to that in wild type. Depositions of IgG and fibrinogen, one of the endogenous antigen for natural IgG, were observed after BAPN+AngII infusion before and after AD development in wild type mice. Deposition of fibrinogen was also observed in mMT mice after BAPN+AngII infusion. The rate of aortic rupture and sudden death was approximately 42% in wild type mice, while that in muMT mouse was 12% (P&lt;0.05). Administration of mouse normal polyclonal IgG to muMT mice resulted in dramatic increase in aortic rupture and sudden death, starting at day 7 of BAPN+AngII infusion, and reaching 69% of rupture rate, indicating the critical role of IgG in AD.

Conclusion

These findings demonstrated B cells and IgG are critically involved in the destructive inflammation of AD pathogenesis. Further, the deposition of fibrinogen, one of the targets of natural IgG, precedes the development of AD. Our findings may provide the conceptual foundation of the diagnostic strategy for on-going tissue destruction and for the therapeutic opportunities to intervene the progressive tissue destruction in AD.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): The Japan Society for the Promotion of Science

Eriodictyon angustifolium extract, but not Eriodictyon californicum extract, reduces human hair greying

OBJECTIVE

Yerba Santa (Eriodictyon angustifolium and Eriodictyon californicum) has been used for many years in traditional medicine. However, the effect of Yerba Santa on melanogenesis has not yet been investigated. We aimed to assess the biological effects of Yerba Santa on hair pigmentation.

METHODS

Yerba Santa extracts were assessed for their cytological effects following X-ray irradiation treatment and then tested directly for the prevention of human hair greying. Ultra-performance liquid chromatography (UPLC) was utilized to identify the individual extract components.

RESULTS

Eriodictyon angustifolium extract significantly increased melanin synthesis in the melanoma cell line through activation of the WNT/MITF/tyrosinase-signalling pathway. In contrast, E. californicum had no effect on melanin synthesis. E. angustifolium extract also demonstrated a protective effect against the damage induced by X-ray irradiation in human keratinocytes. Application of the extracts to subjects who had grey beards demonstrated a reduced number of grey beard hair per year specifically with the E. angustifolium extract. A significant decrease in grey head hair was also observed after application of E. angustifolium extract. Upregulation of gene expression related to melanin production and WNT signalling was observed after the application of E. angustifolium extract. Sterubin was the most abundant flavonoid detected by UPLC in E. angustifolium extract. In addition, sterubin showed the highest difference in terms of quantity, between E. angustifolium and E. californicum extract.

CONCLUSION

Eriodictyon angustifolium extract, which is abundant in sterubin, may be suitable as a potential cosmetic and medical agent for the prevention and improvement of hair greying.

Effective countermeasures for Salmonella contamination in actual oilmeal-manufacturing plant in India

AIMS

Salmonella contamination in the manufacturing process of an overseas oilmeal plant was investigated and countermeasures for Salmonella contamination were evaluated.

METHODS AND RESULTS

Salmonella was detected from deposits and adhered materials inside the main processing equipment. Specifically high contamination was observed in the equipment associated with the meal cooler, with several Salmonella serovars being detected. A number of Salmonella serovars were also detected in the equipment of the fine powder recovery process. To prevent Salmonella contamination of oilmeal products, effective countermeasures that have been employed in Japan were implemented. By removing residues from the equipment and disinfecting the interior of the equipment, a significant decrease in the contamination rate of oilmeal products was achieved compared to before sanitation (P < 0·05).

CONCLUSIONS

Effective countermeasures to control Salmonella contamination in the overseas manufacturing process of oilmeal were established.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report focusing on Salmonella countermeasures in an actual oilmeal-manufacturing plant overseas.

P6494Activation of focal adhesion kinase is involved in pathogenesis of aortic dissection in mice

Background

Aortic dissection (AD) is a fatal disease where the media of the aorta suddenly fail. Currently, Molecular pathogenesis of AD is unknown. Recently, we discovered that the activity of MRTF-A, a mechanosensitive transcriptional regulator, promotes AD development. The activity of MRTF-A is regulated by mechanical stress to cells, which is transduced through focal adhesion and actin dynamics. However, it is currently unknown whether the mechanotransduction mechanism is involved in AD pathogenesis.

Purpose

We investigated the role of focal adhesion kinase (FAK), a signaling molecule that transduces mechanostress from focal adhesion to actin dynamics, in AD pathogenesis.

Methods

We created a mouse model of AD with a continuous infusion of beta-aminopropionitrile (150 mg/kg/day), a collagen crosslink inhibitor, and angiotensin II (1,000 ng/kg/min) (BAPN + AngII) by an osmotic pump. This model caused about 60% death in all mice due to AD rupture within 2 weeks. In this model, we examined the severity and mortality rate of aortic dissection after 2 weeks in mice administered with PND-1186, an orally available FAK inhibitor, and in those treated with vehicle (n=20 for each group). We performed immunochemical staining, immunofluorescence staining and Western blot for activated (phosphorylated) FAK (pFAK) to evaluate the activation status of FAK in the aortic tissue. We also performed transcriptome analysis of the aortic tissue in with and without PND-1186 with BAPN + AngII stimulation before AD development.

Results

Immunochemical staining revealed that FAK was inactive in normal mouse aorta, but was strongly activated in the aortic walls after AD development. Immunofluorescence staining showed that FAK was activated mainly in smooth muscle cells after AD development. Western blot analysis also revealed that FAK was activated in 3 days after BAPN + AngII infusion before AD development, followed by transient reduction at day 7, and re-activation after AD at day 14. Significantly, administration of PND-1186 resulted in a significant reduction in the severity of AD in the aortic arch (1.96±0.41 mm in vehicle group, 0.66±0.29 mm in PND group, P<0.05). In addition, survival rate improved from 36.4% to 80.0% by administration of PND-1186 (P<0.01). In immunofluorescence staining, the PND-1186 treated group showed weaker staining of pFAK. Transcriptome analysis showed that genes for hematopoiesis and immune system were suppressed in PND-1186 treated group.

Conclusions

These findings proved that FAK plays a central role in the pathogenesis of AD probably by transmitting pathological stress to the aortic wall to cause tissue destruction. We propose that FAK is a potential therapeutic target for limiting the fatal destruction of the aortic wall of AD.

P6493Syk activation is a defense mechanism in murine model of aortic dissection

Background

Aortic dissection (AD) is a serious clinical condition with unknown etiology that frequently results in fatal outcome. Recent studies showed essential role of inflammatory response both in promoting AD and aortic aneurysm (AA). However, the difference of the molecular pathogenesis between AD and AA is unclear. Previously, we reported that Syk, a tyrosine kinase that regulates differentiation and activation of inflammatory cells, promotes AA formation in a mouse model.

Objective

In the current study, we investigated the role of Syk in AD.

Methods and results

A mouse AD model was created by continuous infusion of beta-aminopropionitrile (125 mg/kg/day) and angiotensin II (1,000 ng/min/kg) (BAPN+AngII), which caused AD in approximately 80% of mice within 14 days. Immunohistochemical staining for activated (phosphorylated) Syk (pSyk) revealed that Syk was inactive in normal mouse aorta, but was activated in the aortic walls after AD development. Double immunofluorescence staining for pSyk and smooth muscle alpha actin showed that Syk was active not only in the infiltrating inflammatory cells, but also in smooth muscle cells in AD tissue. Western blot analysis revealed that BAPN+AngII treatment caused Syk activation at 3 days before AD development, followed by transient suppression, and reactivation at 14 days after AD development. We examined the significance of Syk activation in AD by treating mice with fostamatinib, a specific Syk inhibitor, before and during BAPN+AngII infusion. Notably, fostamatinib-treated group developed more severe AD compared to the vehicle-treated group. The AD lesion length was 3.80±0.86 mm for vehicle group and 8.87±1.69 mm for fostamatinib group (P<0.05, n=12 for each group). In addition, fostamatinib significantly worsened the mortality of mice due to the rupture of the aorta from 0% to 42% (P<0.05, n=12 for each group). Transcriptome analysis revealed that fostamatinib suppressed both positive and negative regulators of immune response, defense response and inflammatory response.

Conclusions

These findings uncovered the previously unrecognized role of Syk for protecting the aortic tissue in AD pathogenesis, and suggested fundamentally different disease mechanisms of AD and AA.

Post-Extubation Inhaled Nitric Oxide Therapy via High-Flow Nasal Cannula After Fontan Procedure

In 2014, our hospital introduced inhaled nitric oxide (iNO) therapy combined with high-flow nasal cannula (HFNC) oxygen therapy after extubation following the Fontan procedure in patients with unstable hemodynamics. We report the benefits of HFNC-iNO therapy in these patients. This was a single-center, retrospective review of 38 patients who underwent the Fontan procedure between January 2010 and June 2016, and required iNO therapy before extubation. The patients were divided into two groups: patients in Epoch 1 (n = 24) were treated between January 2010 and December 2013, receiving only iNO therapy; patients in Epoch 2 (n = 14) were treated between January 2014 and June 2016, receiving iNO therapy and additional HFNC-iNO therapy after extubation. There were no significant differences between Epoch 1 and 2 regarding preoperative cardiac function, age at surgery, body weight, initial diagnosis (hypoplastic left heart syndrome, 4 vs. 2; total anomalous pulmonary venous return, 5 vs. 4; heterotaxy, 7 vs. 8), intraoperative fluid balance, or central venous pressure upon admission to the intensive care unit. Epoch 2 had a significantly shorter duration of postoperative intubation [7.2 (3.7-49) vs. 3.5 (3.0-4.6) hours, p = 0.033], pleural drainage [23 (13-34) vs. 9.5 (8.3-18) days, p = 0.007], and postoperative hospitalization [36 (29-49) vs. 27 (22-36) days, p = 0.017]. Two patients in Epoch 1 (8.3%), but none in Epoch 2, required re-intubation. Our results suggest that HFNC-iNO therapy reduces the duration of postoperative intubation, pleural drainage, and hospitalization.

Successful catheter ablation of premature ventricular contractions triggering torsade de pointes in a small infant with histiocytoid cardiomyopathy: a case report

Background

A short-coupled variant of torsade de pointes (ScTdP) is rare and resistant to medical treatment. There has not been a reported catheter ablation (CA) of a short-coupled premature ventricular contraction (PVC) triggering ScTdP in an infant.

Case summary

A neonate was referred to our hospital on the day of birth for Wolff–Parkinson–White syndrome, repeated episodes of supraventricular tachycardia, and a left ventricular non-compaction. She underwent CA of an accessory pathway at 72 days of age. On the 5th day after ablation, she had recurrent TdP episodes resistant to various antiarrhythmic drugs and received extracorporeal membrane oxygenation at 86 days of age. She underwent CA of PVCs triggering TdP at 122 days of age and a weight of 3.4 kg. Two types of PVCs triggering TdP were successfully ablated, which originated from the right ventricle (RV). Pre-potentials were recorded at the earliest ventricular activation sites of the targeted PVCs. After the ablation, she had no TdP episodes and the cardiac assist device was removed. However, she died of uncontrolled heart failure at 6 months of age. The histological findings were compatible with histiocytoid cardiomyopathy and abnormal cells were distributed throughout both ventricles. At the ablation site, fibrotic transmural lesions were noted in the RV wall.

Discussion

The PVCs triggering TdP were successfully ablated in a 4-month-old girl with histiocytoid cardiomyopathy. The PVCs were likely caused by triggered activity and associated with abnormal Purkinje cells.

Left ventricular function after a Fontan operation in patients with pulmonary atresia with an intact ventricular septum

OBJECTIVES

In patients with pulmonary atresia with an intact ventricular septum (PA/IVS), there are no reports about the impact of sinusoidal communication (SC) on left ventricular (LV) performance after a Fontan operation; therefore, the purpose of this study was to fill this gap in the literature.

METHODS

We performed a single-centre, retrospective study of 46 patients with PA/IVS. Nineteen patients who underwent the Fontan procedure were enrolled and divided into 2 groups: those with SC (SC group) and those without SC (N group). The 2 groups were compared in terms of postoperative cardiac function.

RESULTS

Thirteen patients were in the SC group (4 patients with right ventricle-dependent coronary circulation) and 6, in the N group. Although 2 of the patients with right ventricular (RV)-dependent coronary circulation showed focal asynergy of the LV wall, others showed no findings of myocardial infarction. The patients' preoperative age and age during the observation period after the Fontan operation did not differ. There was no difference in LV ejection fraction, cardiac index and RV and pulmonary artery pressure before and after the Fontan operation. Preoperative RV volume in the N group was greater than that in the SC group. Brain natriuretic peptide levels were higher in the SC group after the Fontan operation. On ventricular efficacy analysis, contractility was lower (1.8 ± 0.32 vs 2.5 ± 0.40 mmHg/ml/m2, P = 0.001) and ventricular efficacy was worse (1.0 ± 0.15 vs 0.86 ± 0.11, P = 0.046) in the SC group during the postoperative period.

CONCLUSIONS

Compared to patients with PA/IVS without SC, patients with PA/IVS with SC had a low cardiac contractility and decreased cardiac output efficiency after the Fontan procedure.

Electrical disorders in atrial septal defect: genetics and heritability

Atrial septal defect (ASD) is one of the most common types of congenital heart diseases (CHDs). Most ASDs occur sporadically, but some are inherited and associated with cardiac conduction defects such as atrioventricular block (AVB) or bundle branch block. Mutations in genes encoding transcription factor gene TBX5 and NKX2-5, were found in Holt-Oram syndrome (HOS) and ASD with atrioventricular (AV) conduction defects, respectively. HOS is characterized by upper limb anomaly in addition to ASD and AVB (heart-hand syndrome). ASD associated with NKX2-5 is rare but is reported to cause sudden cardiac death (SCD) or cardiomyopathy. We provide a review of these two diseases.

Factors associated with a positive willingness to practise oral health care in the future amongst oral healthcare and nursing students

OBJECTIVES

The purpose of this study was to identify the weak points in the knowledge and attitudes of first-year oral health care and nursing students towards oral health care and to identify the factors associated with their positive willingness to practise oral health care after becoming a health professional in order to develop oral healthcare curricula.

MATERIALS AND METHODS

The subjects were 88 first-year dental students (DSs), 64 dental hygiene students (DHSs) and 119 nursing students (NSs) enrolled in schools in Japan, as of April 2017. A questionnaire was distributed to subjects in each school to assess their knowledge and attitudes towards oral health care.

RESULTS

Less than half knew that oral health care was also provided in cancer hospitals, hospices, acute care hospitals, maternity wards and psychiatric wards. Only 46.2% knew that oral health care was effective in the prevention of aspiration pneumonia. The level of knowledge and attitudes in NSs regarding oral health care were likely to be lowest amongst the student groups. Only NSs' high interest towards oral health care was associated with their positive willingness to practise oral health care in the future although oral health students' high perceptions and interest regarding oral health care were associated with the willingness.

CONCLUSION

This study showed oral healthcare and nursing students' weak points regarding their attitudes and knowledge of oral health care at early stages. Oral health academic staff and professionals should develop effective oral healthcare curricula for oral healthcare students and help nursing staff develop a collaborative nursing oral healthcare curriculum to motivate nursing students.

Evaluation of Factors Associated With Achievement of Biventricular Repair After Bilateral Pulmonary Artery Banding in Patients With Interrupted Aortic Arch

BACKGROUND

At our institution, we perform bilateral pulmonary artery banding (BPAB) as the first-stage palliation for interrupted aortic arch (IAA) with low birth weight or severe subaortic stenosis (SAS). The present study aimed to identify factors that may influence the decision regarding the type of second-stage operation, that is, univentricular palliation or biventricular repair, in these patients.

METHODS

Cardiac catheterization and angiographic data of nine patients with IAA who underwent initial BPAB and subsequent univentricular or biventricular repair were retrospectively analyzed.

RESULTS

Between 2004 and 2014, of nine patients with IAA who underwent initial BPAB, biventricular repair was subsequently performed in six patients (group B) and univentricular repair in three patients (group U). All patients survived. There was no significant intergroup difference in IAA classification, location of ventricular septal defect, presence of 22q11.2 deletion, presence of aberrant right subclavian artery, band diameter, or post-BPAB pulmonary artery pressure and index. Timing of BPAB and the body weight at the time of BPAB, however, differed significantly between the groups ( P = .02). Catheter data before BPAB were not significantly different between the groups, with the exception of the degree of subaortic stenosis (or hypoplasia of the left ventricular outflow tract) expressed as percentage of the normal end-systolic aortic valve annular diameter for patient body surface area. This metric (%SAS before BPAB) was significantly higher in group B (60%-68%) than in group U (47%-60%; P = .04). Among patients for whom baseline %SAS was < 60%, the %SAS did not increase after BPAB.

CONCLUSION

The most important factor that allowed biventricular repair was not the pulmonary artery pressure or diameter but the degree of SAS. Patients who initially had more severe SAS ultimately underwent univentricular repair due to lack of substantial improvement in dimensions of the left ventricular outflow tract after BPAB.

Cardiac resynchronization therapy via transvenous approach in a 2-year-old boy with a complete atrioventricular block after a tetralogy of Fallot repair

Cardiac resychronization therapy (CRT) was performed via transvenous approach in a 2-year-old boy with a tetralogy of Fallot and postoperative severe heart failure, and complete atrioventricular block treated with a dual-chamber pacemaker. Epicardial leads were unavailable because of mediastinitis and the presence of severe bilateral pleural effusions requiring continuous drainage. There were no procedural complications. Biventricular pacing was significantly effective and both mediastinitis and pleural effusions recurred. The transvenous CRT was exchanged for an epicardial CRT after 4 months because of the possibility of a venous obstruction.

Effect of the combined use of enamel matrix derivative and atelocollagen sponge scaffold on osteoblastic differentiation of mouse induced pluripotent stem cells in vitro

BACKGROUND AND OBJECTIVE

Induced pluripotent stem cells (iPSCs) are a candidate cell source in periodontal regenerative therapy. Enamel matrix derivative (EMD) has been shown to regenerate periodontal tissues, and atelocollagen sponge (ACS) is considered a suitable scaffold or carrier for growth factors. This study aimed to investigate the effect of combined use of EMD and an ACS scaffold on cell behaviors and differentiation of mouse iPSCs (miPSCs) in vitro.

MATERIAL AND METHODS

Following embryonic body formation from miPSCs, dissociated cells (miPS-EB-derived cells) were seeded onto ACS with or without EMD, and cultured in osteoblast differentiation medium. Scanning electron microscopy and histological analyses were used to assess cell morphology and infiltration within the ACS. Cell viability (metabolism) was determined using an MTS assay, and expression of mRNA of osteoblastic differentiation markers was assessed by quantitative RT -PCR. Alkaline phosphatase (ALP) staining intensity and activity were evaluated. Mineralization was assessed by von Kossa staining, and calcium content was quantitated using the methylxylenol blue method.

RESULTS

By 24 hours after seeding, miPS-EB-derived cells in both the EMD and control groups had attached to and infiltrated the ACS scaffold. Scanning electron microscopy images revealed that by day 14, many cytoplasmic protrusions and extracellular deposits, suggestive of calcified matrix, were present in the EMD group. There was a time-dependent increase in cell viability up to day 3, but no difference between groups was observed at any time point. The levels expressed of ALP and osterix genes were significantly higher in the EMD group than in the control group. Expression of runt-related transcription factor 2 was increased in the EMD group compared with the control group on day 7. EMD upregulated the expression of bone sialoprotein and osteopontin on day 14, whereas expression of osteocalcin was lower at all time points. The staining intensity and activity of ALP were higher in the EMD group than in the control group. Mineralization levels and calcium contents were significantly higher in the EMD group throughout the observation period.

CONCLUSION

These data suggest that combining ACS with EMD increases levels of osteoblastic differentiation and mineralization in miPS-EB-derived cells, compared with ACS used alone.

Evaluation of the adsorptive behavior of cesium and strontium on hydroxyapatite and zeolite for decontamination of radioactive substances

Removal of radioactive substances, such as cesium (Cs) and strontium (Sr), has become an emerging issue after the Fukushima Daiichi Nuclear Power Plant Disaster. To assess the possibility that hydroxyapatite (HA) and zeolites can be used for removal of radioactive substances, the adsorption capacities of Cs and Sr on the HA and a zeolite were investigated. The influence of Fe ions on Cs and Sr adsorption on the HA and the zeolite was also evaluated, because Fe ions are the most effective inhibitor of Cs adsorption on the zeolite.In the Cs adsorption process on the HA and the zeolite, the zeolite showed a higher adsorption ratio than the HA, and the maximum sorption capacity of the zeolite was calculated as 196 mg/g, whereas the HA showed a higher Sr adsorption ratio than the zeolite. The maximum sorption capacity of Sr on the HA was 123 mg/g. Under coexistence with Fe, Cs adsorption on the zeolite decreased with increasing Fe concentration, reaching 2.0 ± 0.8% at 0.1 M Fe concentration. In contrast, Cs adsorption on the zeolite was improved by adding the HA. In the case of coexistence of the HA, the Cs adsorption on the mixture of the HA and the zeolite was 52.4% ± 3.6 % at 0.1 M Fe concentration, although Cs adsorption on the HA alone was quite low. In the Fe adsorption processes of the HA and the zeolite, the HA exhibited a maximum sorption capacity of 256 mg/g, which was much higher than that of the zeolite (111 mg/g). The high affinity of Fe on the HA contributes to the improvement of the deteriorated Cs adsorption on the zeolite due to Fe ions.

Fabrication of hydroxyapatite thin films on polyetheretherketone substrates using a sputtering technique

Hydroxyapatite (HA) thin films were coated on a polyetheretherketone (PEEK) substrate using a sputtering technique. A thin titanium (Ti) intermediate layer was formed between the HA and the PEEK surface to improve adhesion of the HA film to the PEEK substrate. The coated films were recrystallized using a hydrothermal treatment to reduce the dissolution of the HA film. The films were then characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and a UV-Vis spectrophotometer. A pull-out test was performed to measure the film-to-substrate adhesion strength, and an immersion test was performed in ultra-pure water. In the XRD patterns of the sputtered film with the Ti intermediate layer on the PEEK substrate, small HA peaks and large Ti peaks were observed. After the hydrothermal treatment, the intensity of the HA peaks increased. The transmittance of the HA films with 5 and 10nm Ti intermediate layers was >79% and 68%, respectively, in the visible light wavelength region (400-700nm) after the hydrothermal treatment. The adhesion strength of the hydrothermally treated HA films increased with decreasing thickness of the Ti intermediate layer, and the strength reached 2.7MPa with the 5-nm-thick Ti intermediate layer. In the immersion test, the HA film with a 5-nm-thick Ti intermediate layer without hydrothermal treatment exhibited a released Ti concentration of 42.0±2.4ppb. After hydrothermal treatment, the released Ti concentration decreased to 17.3±1.1ppb.

A type 2 ryanodine receptor variant associated with reduced Ca2+ release and short-coupled torsades de pointes ventricular arrhythmia

BACKGROUND

Ventricular fibrillation may be caused by premature ventricular contractions (PVCs) whose coupling intervals are <300 ms, a characteristic of the short-coupled variant of torsades de pointes (scTdP).

OBJECTIVE

The purpose of this study was to analyze the underlying cardiac ryanodine receptor (RyR2) variants in patients with scTdP.

METHODS

Seven patients with scTdP (mean age 34 ± 12 years; 4 men and 3 women) were enrolled in this study. The RyR2 gene was screened by targeted gene sequencing methods; variant minor allele frequency was confirmed in 3 databases; and the pathogenicity was investigated in silico analysis using multiple tools. The activity of wild-type and mutant RyR2 channels was evaluated by monitoring Ca²⁺ signals of HEK293 cells with a [³H]ryanodine binding assay.

RESULTS

The mean coupling interval of PVCs was 282 ± 13 ms. The 12-lead electrocardiogram had no specific findings except PVCs with an extremely short-coupling interval. Genetic analysis revealed 3 novel RyR2 variants and 1 polymorphism, all located in the cytoplasmic region. p.Ser4938Phe was not detected in 3 databases, and in silico analysis indicated its pathogenicity. In functional analysis, p.Ser4938Phe demonstrated loss of function and impaired RyR2 channel Ca²⁺ release, while 2 other variants, p.Val1024Ile and p.Ala2673Val, had mild gain-of-function effects but were similar to the polymorphism p.Asn1551Ser.

CONCLUSION

We identified an RyR2 variant associated with reduced Ca²⁺ release and short-coupled torsades de pointes ventricular arrhythmia. The mechanisms of arrhythmogenesis remain unclear.