Insights from an electro-mechanical heart failure cell model: Role of SERCA enhancement on arrhythmogenesis and myocyte contraction

Targeting MAPK-ERK/JNK pathway: A potential intervention mechanism of myocardial fibrosis in heart failure

Myocardial fibrosis is a significant pathological basis of heart failure. Overactivation of the ERK1/2 and JNK1/2 signaling pathways of MAPK family members synergistically promotes the proliferation of myocardial fibroblasts and accelerates the development of myocardial fibrosis. In addition to some small molecule inhibitors and Western drugs, many Chinese medicines can also inhibit the activity of ERK1/2 and JNK1/2, thus slowing down the development of myocardial fibrosis, and are generally safe and effective. However, the specific biological mechanisms of ERK1/2 and JNK1/2 signaling pathways in myocardial fibrosis still need to be fully understood, and there is no systematic review of existing drugs and methods to inhibit them from improving myocardial fibrosis. This study aims to summarize the roles and cross-linking mechanisms of ERK1/2 and JNK1/2 signaling pathways in myocardial fibrosis and to systematically sort out the small-molecule inhibitors, Western drugs, traditional Chinese medicines, and non-pharmacological therapies that inhibit ERK1/2 and JNK1/2 to alleviate myocardial fibrosis. In the future, we hope to conduct more in-depth research from the perspective of precision-targeted therapy, using this as a basis for developing new drugs that provide new perspectives on the prevention and treatment of heart failure.

Cell nucleus elastography with the adjoint-based inverse solver

BACKGROUND AND OBJECTIVES

The mechanics of the nucleus depends on cellular structures and architecture, and impact a number of diseases. Nuclear mechanics is yet rather complex due to heterogeneous distribution of dense heterochromatin and loose euchromatin domains, giving rise to spatially variable stiffness properties.

METHODS

In this study, we propose to use the adjoint-based inverse solver to identify for the first time the nonhomogeneous elastic property distribution of the nucleus. Inputs of the inverse solver are deformation fields measured with microscopic imaging in contracting cardiomyocytes.

RESULTS

The feasibility of the proposed method is first demonstrated using simulated data. Results indicate accurate identification of the assumed heterochromatin region, with a maximum relative error of less than 5%. We also investigate the influence of unknown Poisson's ratio on the reconstruction and find that variations of the Poisson's ratio in the range [0.3-0.5] result in uncertainties of less than 15% in the identified stiffness. Finally, we apply the inverse solver on actual deformation fields acquired within the nuclei of two cardiomyocytes. The obtained results are in good agreement with the density maps obtained from microscopy images.

CONCLUSIONS

Overall, the proposed approach shows great potential for nuclear elastography, with promising value for emerging fields of mechanobiology and mechanogenetics.

Associations of ApoE Polymorphisms with Postoperative Atrial Fibrillation and Cardiac Injury in Patients with Coronary Artery Bypass Graft Surgery

Genetic factors may be involved in postoperative atrial fibrillation (PoAF) development and cardiac injury. However, the associations of the apolipoprotein E (ApoE) gene polymorphisms with PoAF and cardiac injury after coronary artery bypass graft surgery (CABG) remain unclear.We recruited 150 patients with CABG, comprising 92 and 58 cases for the ApoE4 and ApoE3 groups, respectively, and analyzed PoAF incidence and the levels of cardiac biomarkers, including N-terminal prohormone of brain natriuretic peptide, cardiac troponin T (cTnT), and cardiac troponin I (cTnI). The linear regression model or logistic regression analysis was applied to investigate the associations of ApoE gene polymorphisms with PoAF and biomarkers for cardiac injury.A total of 58 (38.7%) patients with CABG developed PoAF, with 40 and 18 cases in the ApoE4 and ApoE3 groups (43.5% versus 31.0%, P < 0.05), respectively. Logistic regression analysis revealed that the ApoE4 allele was an independent risk factor for PoAF (OR = 3.340, P = 0.001), while the ApoE3 allele was a protective factor for the PoAF (OR = 0.841, P = 0.043). Patients carrying the ApoE4 allele had higher levels of cTnT and cTnI than those carrying the ApoE3 allele. ApoE3 was a protective factor for cardiac injury (β = -0.220, P = 0.001), whereas ApoE4 was a risk factor for cTnI (β = 0.335, P = 0.015).Our study reveals that the ApoE allele contributes to the occurrence of PoAF and severity of cardiac injury in an allele-dependent manner, with the ApoE4 allele increasing the risk and the ApoE3 allele reducing the risk.