RyR2-targeting therapy prevents left ventricular remodeling and ventricular tachycardia in post-infarction heart failure

BACKGROUND

Dantrolene binds to the Leu⁶⁰¹-Cys⁶²⁰ region of the N-terminal domain of cardiac ryanodine receptor (RyR2), which corresponds to the Leu⁵⁹⁰-Cys⁶⁰⁹ region of the skeletal ryanodine receptor, and suppresses diastolic Ca²⁺ leakage through RyR2.

OBJECTIVE

We investigated whether the chronic administration of dantrolene prevented left ventricular (LV) remodeling and ventricular tachycardia (VT) after myocardial infarction (MI) by the same mechanism with the mutation V3599K of RyR2, which indicated that the inhibition of diastolic Ca²⁺ leakage occurred by enhancing the binding affinity of calmodulin (CaM) to RyR2.

METHODS AND RESULTS

A left anterior descending coronary artery ligation MI model was developed in mice. Wild-type (WT) were divided into four groups: sham-operated mice (WT-Sham), sham-operated mice treated with dantrolene (WT-Sham-DAN), MI mice (WT-MI), and MI mice treated with dantrolene (WT-MI-DAN). Homozygous V3599K RyR2 knock-in (KI) mice were divided into two groups: sham-operated mice (KI-Sham) and MI mice (KI-MI). The mice were followed for 12 weeks. Survival was significantly higher in the WT-MI-DAN (73%) and KI-MI groups (70%) than the WT-MI group (40%). Echocardiography, pathological tissue, and epinephrine-induced VT studies showed that LV remodeling and VT were prevented in the WT-MI-DAN and KI-MI groups compared to the WT-MI group. An increase in diastolic Ca²⁺ spark frequency and a decrease in the binding affinity of CaM to the RyR2 were observed at 12 weeks after MI in the WT-MI group, although significant improvements in these values were observed in the WT-MI-DAN and KI-MI groups.

CONCLUSIONS

Pharmacological or genetic stabilization of RyR2 tetrameric structure improves survival after MI by suppressing LV remodeling and proarrhythmia.

TFEB-mediated lysosomal exocytosis alleviates high-fat diet-induced lipotoxicity in the kidney

Obesity is a major risk factor for end-stage kidney disease. We previously found that lysosomal dysfunction and impaired autophagic flux contribute to lipotoxicity in obesity-related kidney disease, in both humans and experimental animal models. However, the regulatory factors involved in countering renal lipotoxicity are largely unknown. Here, we found that palmitic acid strongly promoted dephosphorylation and nuclear translocation of transcription factor EB (TFEB) by inhibiting the mechanistic target of rapamycin kinase complex 1 pathway in a Rag GTPase-dependent manner, though these effects gradually diminished after extended treatment. We then investigated the role of TFEB in the pathogenesis of obesity-related kidney disease. Proximal tubular epithelial cell-specific (PTEC-specific) Tfeb-deficient mice fed a high-fat diet (HFD) exhibited greater phospholipid accumulation in enlarged lysosomes, which manifested as multilamellar bodies (MLBs). Activated TFEB mediated lysosomal exocytosis of phospholipids, which helped reduce MLB accumulation in PTECs. Furthermore, HFD-fed, PTEC-specific Tfeb-deficient mice showed autophagic stagnation and exacerbated injury upon renal ischemia/reperfusion. Finally, higher body mass index was associated with increased vacuolation and decreased nuclear TFEB in the proximal tubules of patients with chronic kidney disease. These results indicate a critical role of TFEB-mediated lysosomal exocytosis in counteracting renal lipotoxicity.

A rare mechanism of embolic stroke complicating coronary thrombus aspiration

Aspiration thrombectomy is often performed in patients with acute myocardial infarction with high thrombus burden. Current guidelines, however, recommend against it because of stroke risk. We report a case of embolic stroke complicating coronary thrombus aspiration in a 62-year-old man. Aspiration thrombectomy during percutaneous coronary intervention migrated thrombus to the proximal right coronary artery (RCA), and the thrombus was subsequently released into the aorta by backflow of the contrast injection causing aspiration thrombectomy-associated stroke. This is an extremely rare mechanism by which complications arise from failed aspiration thrombectomy.

Search for Gamma-Ray Spectral Lines from Dark Matter Annihilation up to 100 TeV toward the Galactic Center with MAGIC

Linelike features in TeV γ rays constitute a "smoking gun" for TeV-scale particle dark matter and new physics. Probing the Galactic Center region with ground-based Cherenkov telescopes enables the search for TeV spectral features in immediate association with a dense dark matter reservoir at a sensitivity out of reach for satellite γ-ray detectors, and direct detection and collider experiments. We report on 223 hours of observations of the Galactic Center region with the MAGIC stereoscopic telescope system reaching γ-ray energies up to 100 TeV. We improved the sensitivity to spectral lines at high energies using large-zenith-angle observations and a novel background modeling method within a maximum-likelihood analysis in the energy domain. No linelike spectral feature is found in our analysis. Therefore, we constrain the cross section for dark matter annihilation into two photons to ⟨σv⟩≲5×10^{-28}  cm^{3} s^{-1} at 1 TeV and ⟨σv⟩≲1×10^{-25}  cm^{3} s^{-1} at 100 TeV, achieving the best limits to date for a dark matter mass above 20 TeV and a cuspy dark matter profile at the Galactic Center. Finally, we use the derived limits for both cuspy and cored dark matter profiles to constrain supersymmetric wino models.

[A Case of Long-Term Survival of Breast Cancer with Extra-Regional Lymph Node Metastases]

We present the case of a 65-year-old woman who presented with nipple retraction of her left breast. The patient has a family history of breast cancer. She was diagnosed with bilateral breast cancer with left axillary, cervical, and mediastinal lymph node metastasis(right breast cancer, cT1cN0M0, cStage Ⅰ, Luminal A-like, left breast cancer, cT2N3bM1[LYM], Stage Ⅳ, triple negative type). She was recommended chemotherapy due to her inoperable advanced-stage breast cancer. After 6 courses of administration of AC chemotherapy(doxorubicin and cyclophosphamide)and 5 courses of tri-weekly docetaxel chemotherapy, shrinkage of the primary lesion and disappearance of each swollen lymph node were observed via computed tomography. Surgery was performed 11 weeks post-chemotherapy. Residual lesions, less than 10 mm in size in both the left and right breast masses, were observed. No lymph node metastasis was observed. Four years later, no signs of recurrence have been noted.

Stabilizing cardiac ryanodine receptor with dantrolene treatment prevents left ventricular remodeling in pressure-overloaded heart failure mice

Dantrolene (DAN) directly binds to cardiac ryanodine receptor 2 (RyR2) through Leu⁶⁰¹-Cys⁶²⁰ in the N-terminal domain and subsequently inhibits diastolic Ca²⁺ leakage through RyR2. We previously reported that therapy using RyR2 V3599K mutation, which inhibits diastolic Ca²⁺ leakage by enhancing calmodulin (CaM) binding ability to RyR2, prevents left ventricular (LV) remodeling in transverse aortic constriction (TAC) heart failure. Here, we examined whether chronic administration of DAN prevents LV remodeling in TAC heart failure via the same mechanism as genetic therapy. A pressure-overloaded hypertrophy mouse model was developed using TAC. Wild-type (WT) mice were divided into three groups: sham-operated mice (Sham group), TAC mice (TAC group), and TAC mice treated with DAN (TAC-DAN group, 20 mg/kg/day, i.p.). They were then followed up for 8 weeks. The survival rate was higher in the TAC-DAN group (83%) than in the TAC group (49%), and serial echocardiography studies and pathological tissue analysis showed that LV remodeling was significantly prevented in the TAC-DAN group compared to the TAC group. An increase in the diastolic Ca²⁺ spark frequency and a decrease in the binding affinity of CaM to RyR2 were observed at 8 weeks in the TAC group but not in the TAC-DAN group. Stabilization of RyR2 with DAN prevented LV remodeling and improved survival after TAC by enhancing CaM binding to RyR2 and inhibiting RyR2-mediated diastolic Ca²⁺ leakage.

Allergic inflammation disrupts epithelial electrogenic electrolyte transport through cholinergic regulation in the mouse colon

Intestinal transport of electrolytes is regulated by the enteric nervous system. Acetylcholine (ACh) is considered the most important neurotransmitter for electrolyte transport in the colon. However, electrolyte transport regulated by ACh is not fully understood in the colon. We investigated the regulation of electrogenic electrolyte transport by cholinergic agonists in the mouse colon by measuring the short-circuit current (Isc) using an Ussing chamber system. Muscarinic stimulation induced transient electrogenic Cl- secretion, and nicotinic stimulation induced electrogenic K+ secretion to the apical side in the normal mouse colon, and these effects were reduced in the colon of mice with food allergy (FA). Administration of prednisolone to mice with FA suppressed mild inflammation in the colon and allergic symptoms and thereby ameliorated the disruption of electrogenic electrolyte transport induced not only by cholinergic pathway activation but also by electrical field stimulation and intracellular cAMP signaling pathway activation in the colon. These results suggest that the electrogenic electrolyte transport function in the colon is impaired by FA-induced colonic inflammation and that the suppression of inflammation ameliorates the dysfunction of electrogenic electrolyte transport in the colon of mice with FA.

Substantial Reduction of Acute Ischemic Mitral Regurgitation Using Impella in AMI Complicated with Cardiogenic Shock

A 77-year-old female presented with loss of consciousness, blood pressure of 90/60 mmHg, and heart rate of 47 bpm. At admission, highly sensitive Trop-T and lactate were elevated, and an electrocardiogram revealed an infero-posterior ST elevation myocardial infarction. Echocardiography revealed a depressed left ventricular ejection fraction with abnormal wall motion in the infero-posterior region and hyperkinetic apical movement along with severe mitral regurgitation (MR). Coronary angiography showed a hypoplastic right coronary artery, 100% thrombotic occlusion of the dominant left circumflex (LCx) artery, and 75% stenosis in the left anterior descending (LAD) artery. Substantial hemodynamic improvement with the reduction of acute ischemic MR was achieved by the initiation of an Impella 2.5, which is a transvalvular axial flow pump, and successful percutaneous coronary intervention (PCI) was conducted with stents to the LCx. The patient was weaned off the Impella 2.5 in 5 days, received staged PCI to LAD, and was later discharged after completion of the staged PCI to LAD.

Comparison of Percutaneous Coronary Intervention Procedures and Outcomes for Recent and Acute ST-Elevation Myocardial Infarction

Although the primary percutaneous coronary intervention (PCI) is an established treatment for acute ST-elevation myocardial infarction (STEMI), relevant guidelines do not recommend it for recent-STEMI cases with a totally occluded infarcted related artery (IRA). However, PCI is allowed in Japan for recent-STEMI cases, but little is known regarding its outcomes. We aimed to examine the details and outcomes of PCI procedures in recent-STEMI cases with a totally occluded IRA and compared the findings with those in acute-STEMI cases.Among the 903 consecutive patients admitted with acute coronary syndrome, 250 were treated with PCI for type I STEMI with a totally occluded IRA. According to the time between symptom onset and diagnosis, patients were divided into the recent-STEMI (n = 32) and acute-STEMI (n = 218) groups. The background, procedure details, and short-term outcomes were analyzed. No significant differences between the groups were noted regarding patient demographics, acute myocardial infarction severity, or IRA distribution. Although the stent number and type were similar, significant differences were observed among PCI procedures, including the number of guidewires used, rate of microcatheter or double-lumen catheter use, and application rate of thrombus aspiration. The thrombolysis rate in the myocardial infarction flow 3-grade post-PCI did not differ significantly between the groups. Both groups had a low frequency of procedure-related complications. The in-hospital mortality rates were 0% and 4.6% in the recent-STEMI and acute-STEMI groups, respectively (P > 0.05).Although recent-STEMI cases required complicated PCI techniques, their safety, success rate, and in-hospital mortality were comparable to those of acute-STEMI cases.

Angioscopic findings 1 year after percutaneous coronary intervention for chronic total occlusion

BACKGROUND

Chronic total occlusion (CTO) is a high-risk factor for stent thrombosis, but little is known about the difference in neointimal healing between CTO and non-CTO lesions regarding implanted stents. We investigated factors affecting neointimal healing after stent implantation for CTO and non-CTO lesions using angioscopy.

METHODS

We retrospectively evaluated 106 stents in 85 consecutive patients between March 2016 and July 2020. Their average age was 68 ± 11 years, and participants (73 male and 12 female) underwent follow-up angiography and angioscopy 1 year after percutaneous coronary intervention (PCI). The stents (n = 106) were divided into three groups according to the lesion status at the previous PCI: CTO (n = 17), acute coronary syndrome (ACS) (n = 35), and stable coronary artery disease without CTO or non-CTO (n = 54).

RESULTS

The neointimal stent coverage grade was significantly lower in the CTO and ACS groups than in the non-CTO group (0.4 ± 0.5, 0.9 ± 0.8, and 1.4 ± 0.8, respectively, p < 0.001). Thrombi were significantly more frequent in CTO and ACS than in non-CTO (71 %, 51 %, and 15 %, respectively, p < 0.001). The yellow grade in CTO was comparable to that in ACS but significantly higher in CTO than in non-CTO (CTO vs. ACS vs. non-CTO 1.5 ± 0.7, 1.4 ± 0.6, and 0.9 ± 0.7, respectively, p = 0.007).

CONCLUSIONS

Delayed healing occurs in stents implanted for CTO lesions. Longer dual-antithrombotic therapy may be beneficial.

Clinical Characteristics and Prognosis of Life-Threatening Acute Myocardial Infarction in Patients Transferred to an Emergency Medical Care Center

Patients with acute myocardial infarction (AMI) triaged as life-threatening are transferred to our emergency medical care center (EMCC). However, data on these patients remain limited. We aimed to compare the characteristics and AMI prognosis of patients transferred to our EMCC with those transferred to our cardiovascular intensive care unit (CICU) using whole and propensity-matched cohorts.We analyzed the data of 256 consecutive AMI patients transferred from the scene to our hospital by ambulance between 2014 and 2017. The EMCC and CICU groups comprised 77 and 179 patients, respectively. There were no significant between-group age or sex differences. Patients in the EMCC group had more disease severity score and had the left main trunk identified as the culprit more frequently (12% versus 0.6%, P < 0.001) than those in the CICU group; however, the number of patients with multiple culprit vessels did not differ. The EMCC group had a longer door-to-reperfusion time (75 [60, 109] minutes versus 60 [40, 86] minutes, P< 0.001) and a higher in-hospital mortality (19% versus 4.5%, P < 0.001), especially from non-cardiac causes (10% versus 0.6%, P < 0.001), than the CICU group. However, peak myocardial creatine phosphokinase did not significantly differ between the groups. The EMCC group had a significantly higher 1-year post-discharge mortality than the CICU group (log-rank, P = 0.032); this trend was maintained after propensity score matching, although the difference was not statistically significant (log-rank, P = 0.094).AMI patients transferred to the EMCC exhibited more severe disease and worse overall in-hospital and non-cardiac mortality than those transferred to the CICU.

A Longitudinal Study of the Impact of Personal and Professional Resources on Nurses' Work Engagement: A Comparison of Early-Career and Mid-Later-Career Nurses

To predict and ensure a healthy and high-performing nursing workforce, it is necessary to identify the antecedents that promote work engagement, especially among early-career nurses. To date no study has focused on this. This longitudinal survey, administered to 1204 nurses working in seven general hospitals with 200 or more beds in four prefectures in Japan at two different times in 2019, aims to examine the causal relationship between the personal and professional resources for nurses to work vigorously (PPR-N) and work engagement among nurses in the early stages of their careers, considering time as a key mediating factor. The analysis of structural equation modeling using the cross-lagged effect model supported that PPR-N had significant and positive effects on work engagement after 3 months among early-career nurses with less than 10 years of nursing experience. The PPR-N is a reliable antecedent of work engagement, which is typical of early-career nurses. These results may be provided guidance for managers in overseeing the work environment to ensure a thriving sustainable nursing workforce.

Self-assessment scale for the community-based and emergency practice

BACKGROUND

For current medical education, community-based primary care for the elderly is an essential topic. This study aimed to establish a scale of community-based assessment for clinical and emergency practice (C-CEP).

METHODS

A self-assessment scale for C-CEP was developed according to four steps. Initially, we reviewed publications from the societies of the United States, British, and Japan regarding educational goals. In addition, we searched MEDLINE for educational goals regarding attitude, skills, and knowledge. Getting together, we established 23 items as the educational goals of the C-CEP. Second, we collected responses for these 23 items from 5th-grade medical students (n = 195). Third, we conducted an exploratory factor analysis (EFA) using their responses to determine the fundamental structure of the self-assessment scale. Finally, a confirmatory factor analysis (CFA) was performed to assess the fitness of the self-assessment scale developing the EFA, resulting in modification of the items.

RESULTS

In EFA and CFA results, C-CEP Scale consisted of four factors with 15 items: "Attitude and communication in emergency care," Basic clinical skills," "Knowledge of community healthcare," and "Knowledge of evidence-based medicine perseverance." The model fit indices were acceptable (Goodness of Fix Index = 0.928, Adjusted Goodness of Fit Index = 0.900, Comparative Fit Index = 0.979, and Root Mean Square Error of Approximation = 0.045). The values of McDonald's omega as an estimate of scale reliability were more than 0.7 in all four factors. As for test-retest reliability, the intraclass correlation coefficients were ≥ 0.58 for all factors. All four factors of the C-CEP Scale correlated positively with the Medical Professionalism Evaluation Scale subscales.

CONCLUSIONS

We developed a valid and reliable self-assessment scale to assess student competence.

Dantrolene, a stabilizer of the ryanodine receptor, prevents collagen-induced arthritis

Dantrolene inhibits Ca²⁺ leakage from destabilized ryanodine receptors and therefore may serve as a therapeutic agent against endoplasmic reticulum stress-associated diseases. However, its effectiveness in treating autoimmune diseases remains unclear. Here, we investigated the effect of dantrolene on collagen-induced arthritis (CIA) in mice. Oral administration of dantrolene resulted in significantly lower arthritic scores in both male and female CIA mice than in the control mice. Micro-computed tomographic and histological analyses showed that dantrolene suppressed bone and chondral destruction. The serum levels of anti-type II collagen (CII) IgG were positively correlated with the arthritic scores (r = 0.704, p < 0.01). In addition, the serum levels of anti-CII IgG were significantly lower in the dantrolene group than in the control group (p < 0.05). These results demonstrate that oral administration of dantrolene to CIA mice inhibits the production of serum anti-CII IgG and consequently prevents arthritis. Therefore, dantrolene may be a potential anti-rheumatic drug.

Albuminuria predicts worsening renal function at 1 month after transcatheter aortic valve implantation

Background

Worsening renal function (WRF) at short term after transcatheter aortic valve replacement (TAVR) is reportedly associated with subsequent poor clinical outcomes. We previously reported preoperative albuminuria predicted mid-term WRF after TAVR. However, the impact of albuminuria on short-term WRF after TAVR is unknown.

Methods

Overall, 206 patients who underwent TAVR for severe aortic stenosis were investigated retrospectively. Patients were divided into two groups according to the preoperative urinary albumin-to-creatinine ratio (ACR): high (ACR ≥30 mg/g) and low (ACR &lt;30 mg/g). The incidence of 1-month WRF, defined as a decrease in estimated glomerular filtration rate (eGFR) ≥10% from baseline after TAVR, was investigated.

Results

More than half of the examined patients (n=106/206 [51.5%]) had a high ACR. Patients with a high ACR had significantly lower eGFR at baseline than those with a low ACR (49.3 [32.5–57.8] vs. 51.4 [37.7–65.8] mL/min/1.73 m2, p=0.03). Patients with a high ACR more frequently had acute kidney injury (8.5% vs. 1.0%, p=0.01) and 1-month WRF than those with a low ACR (29.2% vs. 12.0%, p=0.002). Multivariate analysis showed a high ACR was independently associated with 1-month WRF (odds ratio, 3.72; 95% confidence interval, 1.72–8.08; p&lt;0.001). Meanwhile, eGFR &lt;60 mL/min/1.73 m2 was not an independent predictor of 1-month WRF (odds ratio, 0.48; 95% confidence interval, 0.22–1.04, p=0.06).

Conclusions

Patients with preoperative albuminuria (ACR ≥30 mg/g) more frequently developed AKI and 1-month WRF after TAVR. Albuminuria was independently associated with 1-month WRF, suggesting albuminuria to be a universal predictor of deterioration of renal function at various time points.

Funding Acknowledgement

Type of funding sources: None.

10-Year Temporal Trends of In-Hospital Mortality and Emergency Percutaneous Coronary Intervention for Acute Myocardial Infarction

Background

The mortality rate of acute myocardial infarction (AMI) has improved dramatically because of reperfusion therapy during the last 40 years; however, recent temporal trends for AMI have not been fully clarified in Japan.

Objectives

The purpose of this study was to elucidate the temporary trend in in-hospital mortality and treatment of AMI for the last decade in the Tokyo Metropolitan area.

Methods

We enrolled 30,553 patients from the Tokyo Cardiovascular Care Unit Network Registry, diagnosed with AMI from 2007 to 2016, as part of an ongoing, multicenter, cohort study. We analyzed the temporal trends in basic characteristics, treatment, and in-hospital mortality of AMI.

Results

The overall emergency percutaneous coronary intervention (PCI) rate significantly increased (P < 0.001). In particular, it remarkably increased in patients older than 80 years of age (58.3% to 70.3%, P < 0.001) and patients with Killip III or IV (Killip III, 46.9% to 65.7%; Killip IV, 65.2% to 76.6%, P < 0.001 for both). The crude and age-adjusted in-hospital mortality remained low (5.2% to 8.2% and 3.4% to 5.5%, respectively) and significantly decreased during the decade (P < 0.001). The in-hospital mortality remarkably decreased in patients older than 80 years of age (17.3% to 12.7%, P < 0.001) and in those with cardiogenic shock (38.5% to 27.3%, P < 0.001).

Conclusions

This large cohort study from Tokyo revealed that in-hospital mortality of AMI significantly decreased with the increase in emergency percutaneous coronary intervention rate over the decade, particularly for high-risk patients such as older patients and those with cardiogenic shock.