Magnetic vagus nerve stimulation alleviates myocardial ischemia-reperfusion injury by the inhibition of pyroptosis through the M2AChR/OGDHL/ROS axis in rats.

BACKGROUND: Myocardial ischemia-reperfusion (I/R) injury is accompanied by an imbalance in the cardiac autonomic nervous system, characterized by over-activated sympathetic tone and reduced vagal nerve activity. In our preceding study, we pioneered the development of the magnetic vagus nerve stimulation (mVNS) system. This system showcased precise vagus nerve stimulation, demonstrating remarkable effectiveness and safety in treating myocardial infarction. However, it remains uncertain whether mVNS can mitigate myocardial I/R injury and its specific underlying mechanisms. In this study, we utilized a rat model of myocardial I/R injury to delve into the therapeutic potential of mVNS against this type of injury. RESULTS: Our findings revealed that mVNS treatment led to a reduction in myocardial infarct size, a decrease in ventricular fibrillation (VF) incidence and a curbing of inflammatory cytokine release. Mechanistically, mVNS demonstrated beneficial effects on myocardial I/R injury by inhibiting NLRP3-mediated pyroptosis through the M2AChR/OGDHL/ROS axis. CONCLUSIONS: Collectively, these outcomes highlight the promising potential of mVNS as a treatment strategy for myocardial I/R injury.

Rapid improvement of heart repair in rats after myocardial infarction by precise magnetic stimulation on the vagus nerve with an injectable magnetic hydrogel.

The imbalance between the sympathetic and the parasympathetic nervous system is one of the main pathogeneses of myocardial infarction (MI). Vagus nerve stimulation (VNS), which restores autonomic nervous balance by enhancing the parasympathetic drive, is shown to have benefits for patients with MI. As a clinically safe and effective remote neuromodulation method, magnetic stimulation is expected to overcome the problems of infection and nerve injury caused by electrode implantation. However, it is difficult to achieve precise stimulation on a single vagus nerve due to the poor focus of the magnetic field. Here, we described a novel magnetic vagus nerve stimulation (mVNS) system, which consisted of an injectable chitosan/ß-glycerophosphate (CS/GP) hydrogel loaded with superparamagnetic iron oxide (SPIO) nanoparticles and a mild magnetic pulse sequence. The injectable hydrogel prepared from clinically safe materials ensured minimally invasive implantation, and the SPIO nanoparticles in the hydrogel mediated the precise magnetic stimulation of a single vagus nerve. Under a mild magnetic field (∼100 mT), a decrease in heart rate and a change in vagus nerve potential were found in rats under in situ injection of a magnetic CS/GP hydrogel. Magnetic stimulation on the vagus nerve for 4 weeks (20 Hz, three times daily, 5 minutes each time) significantly improved the cardiac function and reduced the infarct size of the rats subjected to myocardial infarction, accompanied by suppression of inflammatory cell infiltration and inflammation factor expression. Taken together, these results demonstrated that the mVNS exhibited promising potential for treating myocardial infarction in the clinic.

Some Preliminary Results to Eradicate Leukemic Cells in Extracorporeal Circulation by Actuating Doxorubicin-Loaded Nanochains of Fe3O4 Nanoparticles.

Leukemia is a non-solid cancer which features the malignant proliferation of leukocytes. Excessive leukocytes of lesions in peripheral blood will infiltrate organs, resulting in intumescence and weakening treatment efficiency. In this study, we proposed a novel approach for targeted clearance of the leukocytes in the peripheral blood ex vivo, which employed magnetic nanochains to selectively destroy the leukocytes of the lesions. The nanochains were doxorubicin-loaded nanochains of Fe3O4 nanoparticles which were fabricated by the solvent exchange method combined with magnetic field-directed self-assembly. Firstly, the nanochains were added into the peripheral blood during extracorporeal circulation and subjected to a rotational magnetic field for actuation. The leukocytes of the lesion were then conjugated by the nanochains via folic acid (FA) targeting. Finally, the rotational magnetic field actuated the nanochains to release the drugs and effectively damage the cytomembrane of the leukocytes. This strategy was conceptually shown in vitro (K562 cell line) and the method's safety was evaluated in a rat model. The preliminary results demonstrate that the nanochains are biocompatible and suitable as drug carriers, showing direct lethal action to the leukemic cells combined with a rotational magnetic field. More importantly to note is that the nanochains can be effectively kept from entry into the body. We believe this extracorporeal circulation-based strategy by activating nanochains magnetically could serve as a potential method for leukemia treatment in the future.

A generalized solution procedure for in-plane free vibration of rectangular plates and annular sectorial plates.

A generalized solution procedure is developed for in-plane free vibration of rectangular and annular sectorial plates with general boundary conditions. For the annular sectorial plate, the introduction of a logarithmic radial variable simplifies the basic theory and the expression of the total energy. The coordinates, geometric parameters and potential energy for the two different shapes are organized in a unified framework such that a generalized solving procedure becomes feasible. By using the improved Fourier-Ritz approach, the admissible functions are formulated in trigonometric form, which allows the explicit assembly of global mass and stiffness matrices for both rectangular and annular sectorial plates, thereby making the method computationally effective, especially when analysing annular sectorial plates. Moreover, the improved Fourier expansion eliminates the potential discontinuity of the original normal and tangential displacement functions and their derivatives in the entire domain, and accelerates the convergence. The generalized Fourier-Ritz approach for both shapes has the characteristics of generality, accuracy and efficiency. These features are demonstrated via a few numerical examples.

Wrinkling of Tympanic Membrane Under Unbalanced Pressure.

Mechanics of tympanic membrane (TM) is crucial for investigating the acoustic transmission through the ear. In this study, we studied the wrinkling behavior of tympanic membrane when it is exposed to mismatched air pressure between the ambient and the middle ear. The Rayleigh-Ritz method is adopted to analyze the critical wrinkling pressure and the fundamental eigenmode. An approximate analytical solution is obtained and validated by finite element analysis (FEA). The model will be useful in future investigations on how the wrinkling deformation of the TM alters the acoustic transmission function of the ear.