The relationships among the pulse rate, use of beta-blockers, and prognosis in patients with ischemic heart disease in a real-world database using a storage system

Background

The use of β-blockers has the effect of improving the prognosis of patients with ischemic heart disease (IHD). One of the underlying mechanisms is a decrease in the cardiac load due to a reduction in the heart rate.

Purpose

To clarify the relationships among the pulse rate, the use of β-blockers, and the prognosis in patients with IHD in a multicenter study using a storage system.

Methods

The Clinical Deep Data Accumulation System (CLIDAS) collects (1) basic patient information, prescriptions, and laboratory data from electronic medical records from the Standardized Structured Medical Information eXchange (SS-MIX2) standard storage, and (2) the results of physiological tests, cardiac catheterization, and cardiac catheter intervention reports from the SS-MIX2 extended storage. 8540 cases who underwent cardiac catheterization from 6 university hospitals and the national cardiovascular center in Japan were registered (male: 77%, average age: 70.2 years). We evaluated these patients' pulse rate at admission and at the discharge of cardiac catheterization in 6,598 patients. We divided the pulse rates at discharge into quartiles (Q1: <60, Q2: 60–66, Q3: 67–75, Q4: ≥76 bpm), and we analyzed the relationship between the pulse rate and the prognosis by dividing the patients into the stable angina group (n=2,631) and the acute coronary syndrome (ACS) group (n=2,394). Regarding the use of β-blockers, we compared the pulse rates of the patients taking carvedilol (n=1,728) and those taking bisoprolol (n=2,761) at admission and discharge. Major adverse cardiovascular events (MACE) were defined as cardiovascular death, non-fatal myocardial infarction, unstable angina, heart failure, stroke, and other hospitalized cardiovascular events.

Results

A total of 600 MACEs occurred during an average observation period of 890 days. The incidence of cardiovascular events was significantly higher in the Q4 patients in the stable angina group (hazard ratio 1.79, 95% confidence interval 1.32–2.41, but there was no significant difference among the four pulse rate subgroups in the ACS group. The bisoprolol-treated patients had lower pulse rates at discharge (67.4±12.2 vs. 68.8±11.8 bpm, p<0.001) and a lower percentage of patients in the Q4 group (21.2 vs. 24.9%, p=0.005) compared to the carvedilol-treated patients. The pulse rate at admission was similar in the bisoprolol- and carvedilol-treated patients (74.3±19.3 vs. 73.2±29.5 bpm, p=0.328).

Conclusion

In a real-world database using a storage system, a pulse rate of ≤75 bpm was associated with a good prognosis in patients with ACS. Compared to carvedilol, bisoprolol was associated with a decreased pulse rate at discharge.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Kowa Company, Ltd.

Clinical Deep Data Accumulation System (CLIDAS) reveals lipid paradox in guideline-defined high risk Japanese patients after PCI

Background

Japanese clinical guidelines recommend a stratification of the risks and LDL-cholesterol (LDL-C) treatment goals for patients with coronary artery disease after percutaneous coronary intervention (PCI), i.e. <100 mg/dL for normal risk patients and <70 mg/dL for high risk patients; however, less is known about the association between baseline LDL-C values and long-term prognosis.

Purpose

To investigate the association between LDL-C goals and baseline LDL-C levels in relation to major adverse cardiovascular events (MACE) among high-risk patients after PCI, using a real-world database.

Methods

We developed the Clinical Deep Data Accumulation System (CLIDAS) that acquires clinical data directly from hospital information system, and implemented the system in 6 university hospitals and the national cardiovascular center in Japan. The CLIDAS database accumulates data regarding patient background, laboratory data, prescriptions, electrocardiogram, echocardiogram, PCI report, and long-term prognosis. We retrospectively analyzed 8540 consecutive patients who underwent PCI during April 2014 and March 2020 in participating hospitals, and classified them into the normal risk group (n=3712, 43%) and the high risk group [n=4828, 57%, with any of acute coronary syndrome (ACS), familial hypercholesterolemia (FH), or diabetes with additional risk factor(s)], for which LDL-C goals are <100 mg/dL and <70 mg/dL, respectively, according to the Japanese Atherosclerosis Society guidelines or the diagnosis and prevention of atherosclerotic cardiovascular diseases. The primary outcome was the time to first occurrence of MACE, a composite of cardiovascular death, stroke, myocardial infarction, and coronary revascularization in associations with baseline LDL-C levels and patient background.

Results

Proportion of male (77% vs. 77%) and age (71±11 vs. 70±11) were similar between 2 groups. The prevalence of ACS at the index PCI (0% vs. 62%), FH (0% vs. 2%), hypertension (61% vs. 86%), diabetes (11% vs. 67%), dyslipidemia (73% vs. 84%), hemodialysis (4% vs. 9%), peripheral artery disease (5% vs. 9%), smoking (16% vs. 30%), and prescription of statins (79% vs. 86%) were significantly higher in the high risk group. Among patients in the high risk group, but not in the normal risk group, baseline LDL-C <70 mg/dL was paradoxically associated with higher risk of MACE (P<0.0001 by Log-rank test) (Figure). The Cox proportional hazard model confirmed that the high risk group (risk ratio 1.54, 95% CI [1.31–1.81]), baseline LDL-C <70mg/dL (risk ratio 1.44, 95% CI [1.18–1.75]), baseline age (risk ratio 1.36, 95% CI [1.28–1.45] per 10 year), and prescription of statins (risk ratio 0.80, 95% CI [0.66–0.96]) were significantly associated with the risk of MACE in this population.

Conclusion

The CLIDAS real-world database revealed that baseline low LDL-C paradoxically associated with an increased risk of MACE among guideline-defined high risk patients after PCI.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Jichi Medical University, Tochigi, Japan, and Kowa

The left ventricular remodeling assessment by cardiac magnetic resonance in chronic aortic regurgitation; implications for outcome

Background

Chronic aortic regurgitation (AR) causes left ventricular (LV) volume overload resulting in progressive LV remodeling, which negatively affect clinical outcome. Clinical Guidelines recommend assessment of LV remodeling by echocardiography, but little is known about comparative remodeling quantification by cardiac magnetic resonance (CMR) and association with outcomes.

Purpose

To assess LV remodeling in AR by CMR, compared with echocardiographic measures and determine its impact on clinical outcome.

Methods

Patients with native, ≥moderate, chronic AR by echocardiography who underwent CMR exam within 90 days of diagnosis from January 2012 to February 2020 were enrolled. The endpoint was a composite of death, heart failure hospitalization, and heart failure symptom exacerbation during follow-up.

Results

The 178 patients included had median age (IQR) of 58 years (44–69), and most (88%, n=158) presented with no or minimal symptoms (NYHA class I/II). At diagnosis symptomatic vs. no/minimal symptoms patients presented with much more advanced LV remodeling by CMR (EDVI 133 [83–151] vs. 96 [80–123] p=0.024, ESVI 66 [46–85] vs. 42 [30–58], P=0.001) while echocardiography showed limited differences (EDVI 76 [57–93] vs. 65 [54–87] p=0.507, ESVI 38 [30–58] vs. 27 [20–42], p=0.072). During follow-up (3.3 years [1.6–5.8]), aortic valve replacement (AVR) was performed in 49 patients. In patients with no/minimal symptoms, the composite endpoint occurred in 54 (34%) patients including eight deaths and 30 heart failure hospitalizations. Patients with LV end-systolic volume index (LVESVi) >45 ml/m2 by CMR had higher likelihood for composite endpoint (Panel A) confirmed in multivariate models, adjusting for age, sex, AVR (time-dependent), EuroSCORE2, and LV End-systolic-dimension-index (LVESDi) >25 mm/2, with adjusted hazard ratio 1.84 [1.02–3.33], p<0.044 (Panel B). LVESVi by CMR was at least as powerful in determining clinical outcomes as guideline-recommended Doppler-Echocardiographic variables.

Conclusion

Assessment of LV remodeling by CMR in patients with clinically significant AR is feasible in routine clinical practice, detects with high sensitivity LV remodeling associated with development of HF symptoms and is independently predictive of clinical outcome. Hence, CMR provides a powerful tool for evaluation and risk stratification of patients with AR.

Funding Acknowledgement

Type of funding sources: None. Panel APanel B

Muscle stretching induces twitch contractions without activation of stretch-activated channels in intact rat trabeculae

Introduction

Mechano-electric coupling (MEC) means that muscle stretching can induce action potentials. Stretch-activated channels (SACs) have been believed to play important roles in their induction.

Purpose

To investigate what degree of muscle stretching can induce MEC-mediated action potentials and what roles SACs play in their induction.

Methods

Trabeculae were obtained from right ventricles of rat hearts. Force was measured with a strain gauge, sarcomere length (SL) with a laser diffraction technique, and [Ca2+]i with fura-2 (24°C). The SL was set at 2.0 μm at the resting condition. Trabeculae were stimulated electrically at 400-ms intervals for 7.5 s. Various degrees of muscle stretching were applied at 500 ms after the last stimulus of the electrical train to determine the minimal SL (SL-AP) at which an action potential or a twitch contraction was induced by the stretching (0.7 mM [Ca2+]o).

Results

The SL-AP was 2.34±0.02 μm (n=8) when trabeculae were stretched rapidly from a SL of 2.0 μm (400-ms stimulation intervals, 0.7 mM [Ca2+]o). The SL-AP was not changed by increasing the stimulation intervals from 400 to 2000 ms (n=7), by increasing [Ca2+]o from 0.7 to 2 mM (n=8), and by adding 1 μM isoproterenol (n=8), suggesting that Ca2+ loading within the myocardium has no effect on the SL-AP. Surprisingly, the SL-AP was not changed by adding 5 μM GsMTx4 (n=8), 10 mM Gd3+ (n=9), 100 μM (n=8) and 200 μM streptomycin (n=11), revealing that SACs play no roles in the determination of SL-AP. The SL-AP was not changed by adding 1 μM ryanodine (n=5) and 30 μM cyclopiazonic acid and was not changed by adding 3 μM diphenyleneiodonium chloride (n=8) and 10 μM colchicine, suggesting that Ca2+ leak from the SR and activation of NADPH oxidase has no effect on the SL-AP. In contrast, elevation of temperature from 23 to 36°C decreased the SL-AP from 2.35±0.01 to 2.34±0.02 μm (p<0.05, n=7). Elevation of extracellular K+ ([K+]o) from 5 to 10 mM increased the SL-AP from 2.35±0.01 to 2.38±0.01 μm (p<0.01, n=7), while reduction of [K+]o to 5 mM decreased it to 2.36±0.01 μm (p<0.05, n=7), suggesting that depolarization of membrane potential suppresses MEC-mediated twitch contractions. The SL-AP was increased from 2.34±0.01 to 2.36±0.01 μm (p<0.01, n=7) when stretching was applied at a shorter interval after the last stimulus, i.e., 200 ms. After electrical stimulation at 300-ms stimulation intervals for 30 s, arrhythmias were induced by a MEC-mediated twitch contraction in 6 out of 9 trabeculae when stretching was applied at 500 ms after the last stimulus, while they were induced only in 2 out of 9 trabeculae without the stretching (4 mM [Ca2+]o, 1 μM isoproterenol).

Conclusions

These results suggest that muscle stretching causes membrane excitation, which potentially induces arrhythmias and that activation of SACs, Ca2+ release from the SR, and activation of NADPH oxidase by muscle stretching are not involved in the excitation.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Scientific Research (C) from Japan Society for the Promotion of Science.

OS05.4.A Do neurocognitive deficits explain the differences between brain tumour patients and their proxies assessing the patient’s I-ADL?

BACKGROUND

Neurocognitive deficits are common among brain tumour patients, and may impact on patient awareness of deficits in instrumental activities in daily life (IADL). This study aimed to examine differences between patient-reported and proxy-reported assessments of the patient’s performance of IADL, and whether the level of (dis)agreement is associated with neurocognitive deficits.

MATERIAL AND METHODS

A phase III EORTC questionnaire measuring IADL in brain tumour patients (EORTC IADL-BN32) and six neurocognitive test measures were administered as part of a larger multicentre international study designed to develop a brain tumour specific IADL questionnaire. Bland-Altman plots and Mann-Whitney U tests were used to evaluated patient- and proxy-reported IADL on a group level. Subsequently, Mann-Whitney U tests were performed to compare patient-proxy difference scores (patient IADL score - their proxy IADL score) between patients who were considered clearly neurocognitively impaired (≥2 neurocognitive test measures; ≤2.0 SD below healthy controls) and patients who were not. Furthermore, multinomial logistic regression analyses were performed to examined which sociodemgraphic, clinical, and particularly neurocognitive variables were independently associated with patients and proxies differing in their evaluation of patient’s IADL.

RESULTS

Patients (N=81) and proxies (N=81), on group level, did not significantly differ on either the IADL individual item or scale scores. However, significant differences were found on patient-proxy difference scores between patients who were (N=37) and were not (N=44) considered clearly neurocognitively impaired for 10/32 individual items and one of the scales (i.e. Scale 4: Administrative tasks), all showing that the proxies of clearly neurocognitively impaired patients reported more problems relative to the patients themselves, compared to proxies of patients not clearly neurocognitively impaired. Furthermore, for each scale, a neurocognitive variable, either impaired information processing speed, cognitive flexibility, verbal fluency or the number of neurocognitive test measures impaired, was found to be independently associated with proxies reporting more problems. For 4/5 scales, a clinical variable was additionally independently associated with proxies reporting more problems. Only one variable was independently associated with patient reporting more problems, namely being in active treatment was found to be associated with patients reporting more problems on Scale 4: Administrative tasks.

CONCLUSION

Results imply a consistent trend of clearly neurocognitively impaired patients underreporting problems with IADL compared to their proxies. It would therefore be advised to administer both the patient- and proxy-version of the EORTC IADL-BN32, particularly if neurocognitive deficits are presumed.

CMR feature tracking cloud assess right ventricular functional reserve with pulmonary arterial hypertension

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): JSPS KAKENHI, Grant-in-Aid for Early-Career Scientists.

Background

  Pulmonary arterial hypertension (PAH) remains a fatal disorder characterized by elevated pulmonary arterial pressure. Survival of the patients with PAH is determined from right ventricular (RV) function. CMR has become an attractive modality for following up and providing prognosis in such patients, and CMR feature tracking has been used as a newer useful parameter to assess RV function. However, it has not yet been determined whether CMR feature tracking can assess RV functional reserve in patients with PAH.

Purpose

We investigated whether CMR feature tracking can estimate RV functional reserve using a rat model with PAH.

Methods

 Rats were received injections with monocrotaline (MCT-rats, n = 19) or solvent (Ctr-rats, n = 5). Four weeks after the injections, we performed CMR on 7-T MRI scanner and imaged retrospective ECG-gated cine MR (16 phases/beat). RV ejection fraction (RVEF) and RV strain were analyzed before and after addition of 0.5∼3 nmol endothelin-1 (ET-1). After the measurements, we dissected trabeculae (length = 1.45 ± 0.07 mm, width = 334 ± 27 µm, thickness = 114 ± 6 µm) from the RVs of rat hearts. Trabeculae were electrically stimulated with 2-s intervals at extracellular Ca2+ of 0.7 and 2.0 mmol/L (24°C). Force and maximum dF/dt (dF/dtmax) were then measured using a silicon strain gauge in the absence and presence of 0.1 µM ET-1.

Results

 MCT-rats showed higher systolic RV pressure (RVP), lower RVEF, and lower RV global longitudinal strain (RVGLS) in CMR imaging and showed lower developed force and lower dF/dtmax in their trabeculae. Correlation between RVGLS and dF/dtmax was higher (r = 0.53, p < 0.05) than that between RVEF and dF/dtmax (r = 0.24). In 5 MCT-rats with preserved RVEF (>50%), RVGLS had already been reduced, suggesting that RVGLS is reduced earlier than RVEF. ET-1 increased developed force and dF/dtmax in trabeculae from MCT-rats (12.2 ± 5.7 to 17.4 ± 3.1 mN/mm2 and 0.08 ± 0.03 to 0.14 ± 0.06 mN/mm2/sec, respectively, n = 6), and ET-1 also increased RVP in MCT-rats and Ctr-rats (49.0 ± 19.3 to 59.7 ± 16.8 mmHg in MCT-rats, n = 6, 17.3 ± 7.5 to 20.4 ± 7.8 mmHg in Ctr-rats, n = 2). According to RV global circumferential strain (RVGCS) and RVEF, we could divide MCT-rats into three groups as follows: MCT-rats with reduced-RVGCS (> -20%)/preserved-RVEF (> 50%), MCT-rats with increased-RVGCS (< -30%)/preserved-RVEF and MCT-rats with reduced-RVGCS/reduced-RVEF. ET-1 reduced RVGCS in MCT-rats with reduced-RVGCS/preserved-RVEF, while ET-1 did not change RVGCS in MCT-rats with increased-RVGCS/preserved-RVEF. MCT-rats with reduced-RVGCS/reduced-RVEF died after injection of ET-1.  In Ctr-rats, ET-1 did not change RVGCS and RVEF.  These results suggest that RVGCS can be useful to assess RV functional reserve.

Conclusion

 CMR feature tracking can estimate RV functional reserve earlier and more accurately than RVEF in rats with PAH.  RV strain may become an important parameter to assess RV functional reserve in patients with PAH.

Probing the Symmetry Energy with the Spectral Pion Ratio

Many neutron star properties, such as the proton fraction, reflect the symmetry energy contributions to the equation of state that dominate when neutron and proton densities differ strongly. To constrain these contributions at suprasaturation densities, we measure the spectra of charged pions produced by colliding rare isotope tin (Sn) beams with isotopically enriched Sn targets. Using ratios of the charged pion spectra measured at high transverse momenta, we deduce the slope of the symmetry energy to be 42<L<117  MeV. This value is slightly lower but consistent with the L values deduced from a recent measurement of the neutron skin thickness of ^{208}Pb.

Evaluation of redox potentials of cathode materials of alkali-ion batteries using extended DFT+U+U↑↓ method: The role of interactions between the electrons with opposite spins

Limitations of the DFT+U approach (e.g., in Dudarev's formulation) applied for accurate evaluation of redox potentials of cathode materials of alkali-ion batteries with U parameters calculated via the linear response (LR) method are discussed. In contrast to our previous studies, where redox potentials of several cathode materials have been calculated in a good agreement with experiment (e.g., NaMnO₂, LiFePO₄, and LiTiS₂), herein, we analyze other cathode materials, such as LiNiO₂ and Ni- and V-containing phosphates for which this method provides much underestimated redox voltages. We ascribe this limited predictive power of the DFT+U method, parameterized via LR, to the absence of corrections of Coulomb interactions between the electrons with opposite spins. Using the recently proposed extended DFT+U+U_↑↓ functional, which includes the aforementioned corrections, we show how redox potentials of Ni- and V-based compounds could be calculated in a much better agreement with experiment, also proposing a procedure of parameterization of such calculations. Thus, our extended method allows us to calculate redox potentials of several important materials more accurately while retaining good agreement with experiment for structures where the standard DFT+U method also accurately predicts electrochemical properties.

The feasible maintenance dose of corticosteroid in Takayasu arteritis in the era of biologic therapy

Objective: Although biologic agents are used in Takayasu arteritis (TAK), corticosteroids are still the mainstay of treatment. This study aimed to investigate the feasible maintenance dose of prednisolone (PSL) in the biologic therapy era.Method: We enrolled 93 patients with TAK who satisfied the criteria of the American College of Rheumatology and visited our department from 2008 to 2018. The clinical characteristics and PSL dose of the patients were retrospectively evaluated.Results: The mean ± sd maintenance dose of PSL was 5.0 ± 3.0 mg/day. In patients having TAK for > 20 years, PSL discontinuation and drug-free status were achieved in 27.2% and 18%, respectively. Although tapering the PSL dose to 10 mg/day was achieved within 12 months, tapering to 5 mg/day required 10 years. Relapse significantly interfered with the PSL dose reduction. The clinical characteristics of patients with relapse included a lower rate of combination therapy using immunosuppressants. Moreover, biologics were used in > 60% of patients with relapse. Tapering of PSL was significantly possible in patients receiving biologics and additional relapse was observed in 6.3% and 50% of patients with and without biologics, respectively. Such PSL-sparing effect enabled the reduction of the median PSL dose from 10 to 5 mg/day. Steroid discontinuation was achieved in some patients.Conclusions: The use of biologics significantly reduced the PSL dose in relapsed patients. A PSL dose of ≤ 5 mg/day is a feasible target for TAK, especially when biologic agents are used. Nevertheless, corticosteroid discontinuation may also be the target in some patients.

Quasifree Neutron Knockout Reaction Reveals a Small s-Orbital Component in the Borromean Nucleus ^{17}B

A kinematically complete quasifree (p,pn) experiment in inverse kinematics was performed to study the structure of the Borromean nucleus ^{17}B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for 1s_{1/2} and 0d_{5/2} orbitals, and a surprisingly small percentage of 9(2)% was determined for 1s_{1/2}. Our finding of such a small 1s_{1/2} component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in ^{17}B. The present work gives the smallest s- or p-orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of s or p orbitals is not a prerequisite for the occurrence of a neutron halo.

The accuracy of fine needle aspiration cytology in the clinical diagnosis of minor salivary gland tumours

The objective of this study was to investigate the accuracy of fine needle aspiration cytology (FNAC) and biopsy for the clinical diagnosis of minor salivary gland tumours (MSGTs). This retrospective study of 32 MSGT cases was conducted over a 5-year period. Clinical features including age, sex, and location of the tumour were obtained from the patient clinical records. All cases were also assessed histologically according to the 2017 World Health Organization Classification of Head and Neck Tumours. The results of FNAC and biopsy were correlated with those of histopathology, and their sensitivity, specificity, and diagnostic efficacy were calculated using histopathology as the gold standard. Eighteen malignant MSGTs (56.3%) and 14 benign MSGTs (43.8%) were diagnosed by pathological diagnosis. The most common malignant tumour was mucoepidermoid carcinoma (seven cases, 38.9%). Most benign cases were pleomorphic adenomas (13 cases, 92.9%). FNAC was performed for 23 cases and biopsy for 13 cases. The sensitivity and specificity of FNAC were 66.7% and 91.0%, respectively, while those of biopsy were 90.0% and 100.0%, respectively. Although FNAC is a minimally invasive and cost-effective procedure, it is less accurate than biopsy in the assessment of MSGTs. Repeated FNAC or biopsy should be considered in negative and unsatisfactory FNAC cases.

Cumulative incidence of femoral localized periosteal thickening (beaking) preceding atypical femoral fractures in patients with rheumatoid arthritis

The incidence of localized periosteal thickening (LPT, also termed beaking) of the lateral cortex that often precedes an atypical femoral fracture (AFF) was not high in patients with rheumatoid arthritis (RA) but incomplete AFFs developed in two patients. Higher-dose prednisolone was a significant risk factor for LPT in patients with RA.

INTRODUCTION

Atypical femoral fractures (AFFs) are stress fractures; bisphosphonate (BP) use is a major risk factor for the development of such fractures. Localized periosteal thickening (LPT, also termed beaking) of the lateral cortex often precedes a complete or incomplete AFF. We evaluated the incidence of latent LPT in patients with rheumatoid arthritis (RA), to evaluate LPT progression, and to define LPT risk factors.

METHODS

A total of 254 patients with RA were included; all underwent annual X-ray evaluation, dual-energy X-ray absorptiometry, and analyses of serum and bone metabolic markers for 2-3 years. LPT of the lateral cortex was sought in femoral X-rays.

RESULTS

The incidence of LPT was 2.4% (6/254). Among patients on both BP and prednisolone (PSL) at enrollment, the incidence was 2.3% (3/131). Two femurs of two patients with LPT developed incomplete AFFs; LPT was extensive and associated with endosteal thickening. One patient had been on BP and PSL and microscopic polyangiitis was comorbidity. The other was on a selective estrogen receptor modulator and PSL. A daily PSL dose >5 mg (OR 11.4; 95%CI 2.15-60.2; p = 0.004) and higher-dose methotrexate (OR 1.22; 95%CI 1.01-1.49; p = 0.043) were significant risk factors for LPT.

CONCLUSIONS

The incidence of latent LPT was not high (2.4%) but incomplete AFFs developed in two RA patients. Higher-dose PSL because of a comorbid disease requiring glucocorticoid treatment other than RA or refractory RA were risk factors for LPT; X-ray screening for latent LPT would usefully prevent complete AFFs.

Surface Localization of the Dineutron in ^{11}Li

The formation of a dineutron in the ^{11}Li nucleus is found to be localized to the surface region. The experiment measured the intrinsic momentum of the struck neutron in ^{11}Li via the (p,pn) knockout reaction at 246  MeV/nucleon. The correlation angle between the two neutrons is, for the first time, measured as a function of the intrinsic neutron momentum. A comparison with reaction calculations reveals the localization of the dineutron at r∼3.6  fm. The results also support the density dependence of dineutron formation as deduced from Hartree-Fock-Bogoliubov calculations for nuclear matter.

Mitochondrial connexin43 affects arrhythmogenesis with modulation of mitochondrial KATP channels

Introduction

Connexin43 (Cx43) forms gap junction channels in ventricular muscle and also exits in the inner mitochondrial membrane (mCx43). We have previously reported that carbenoxolone, a blocker of Cx43, increased the occurrence of arrhythmias with modulation of mitochondrial KATP channels (mKATP).

Purpose

To examine how mCx43 and mKATP affect arrhythmogenesis, using cardiac-specific Cx43-deficient (Cx43−/−) mice.

Methods

To generate cardiac-specific Cx43−/− mice, Cx43flox/flox mice were crossed with α-myosin heavy chain (Myh6)-cre+/− mice. The resulting offspring, Cx43flox/flox/ Myh6-cre+/− mice (Cx43−/− mice) and their littermates (Cx43+/+ mice), were used. Trabeculae were dissected from right ventricles of mouse hearts (length ∼0.9 mm, width ∼200 μm, thickness ∼80 μm). Force was measured with a strain gauge, and intracellular Ca2+ (Cai) with fura-2 and a CCD camera (22°C). To assess arrhythmogenesis, the minimal extracellular Ca2+ concentration (Caomin), at which arrhythmias were induced by electrical stimulation (0.3-s stimulus intervals, 100 nM isoproterenol), was determined in mouse trabeculae. Using isolated single ventricular myocytes, mitochondrial membrane potential (ΔΨm) was estimated with tetramethylrhodamine methylester (TMRM) fluorescence, ROS production was estimated with 2',7'-dichlorofluorescein (DCF) fluorescence, and Ca2+ spark frequency was measured with fluo-4 and confocal microscopy. To investigate the roles of mKATP, 0.1 mM diazoxide, a mKATP channel opener, and 0.2 mM 5-hydroxydecanoic acid (5-HD), a mKATP channel inhibitor, were used.

Results

Most of Cx43−/− mice suddenly died within 8 weeks (p&lt;0.01). Cx43 was present in the inner mitochondrial membrane in Cx43+/+ mice, while it was not present in Cx43−/− mice. The resting and developed force and Cai transients by electrical stimulation (2-s stimulus intervals) showed no difference between Cx43−/− and Cx43+/+ mouse trabeculae (n=7). The Caomin in Cx43−/− mice was lower than that in Cx43+/+ mice (p&lt;0.01), and diazoxide increased the Caomin in Cx43−/− mice (p&lt;0.01), suggesting that arrhythmogenesis is increased in Cx43−/− mice and is decreased by diazoxide. Ca2+ spark frequency and DCF oxidation rate in Cx43−/− mice were higher than those in Cx43+/+ mice (p&lt;0.01). They were decreased by diazoxide and were increased by 5-HD (p&lt;0.01). TMRM fluorescence was decreased after electrical stimulation (1-s stimulus intervals) in Cx43−/− mice and was further decreased by 5-HD (p&lt;0.01), suggesting depolarization of ΔΨm in Cx43−/− mice. Such decrease in TMRM fluorescence in Cx43−/− mice was suppressed by diazoxide and did not occur in Cx43+/+ mice.

Conclusions

These results suggest that with modulation of mKATP, mCx43 plays important roles in ΔΨm determination, ROS production, and Ca2+ leak from the sarcoplasmic reticulum, thereby affecting arrhythmogenesis. Therefore, it is likely that mCx43 and mKATP could become a therapeutic target for controlling arrythmias.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Scientific Research (C) from Japan Society for the Promotion of Science