Wearable multi-channel microelectrode membranes for elucidating electrophysiological phenotypes of injured myocardium

Understanding the regenerative capacity of small vertebrate models has provided new insights into the plasticity of injured myocardium. Here, we demonstrate the application of flexible microelectrode arrays (MEAs) in elucidating electrophysiological phenotypes of zebrafish and neonatal mouse models of heart regeneration. The 4-electrode MEA membranes were designed to detect electrical signals in the aquatic environment. They were micro-fabricated to adhere to the non-planar body surface of zebrafish and neonatal mice. The acquired signals were processed to display an electrocardiogram (ECG) with high signal-to-noise-ratios, and were validated via the use of conventional micro-needle electrodes. The 4-channel MEA provided signal stability and spatial resolution, revealing the site-specific electrical injury currents such as ST-depression in response to ventricular cryo-injury. Thus, our polymer-based and wearable MEA membranes provided electrophysiological insights into long-term conduction phenotypes for small vertebral models of heart injury and regeneration with a translational implication for monitoring cardiac patients

Two-Point Stretchable Electrode Array for Endoluminal Electrochemical Impedance Spectroscopy Measurements of Lipid-Laden Atherosclerotic Plaques

Four-point electrode systems are commonly used for electric impedance measurements of biomaterials and tissues. We introduce a 2-point system to reduce electrode polarization for heterogeneous measurements of vascular wall. Presence of endoluminal oxidized low density lipoprotein (oxLDL) and lipids alters the electrochemical impedance that can be measured by electrochemical impedance spectroscopy (EIS). We developed a catheter-based 2-point micro-electrode configuration for intravascular deployment in New Zealand White rabbits. An array of 2 flexible round electrodes, 240 µm in diameter and separated by 400 µm was microfabricated and mounted on an inflatable balloon catheter for EIS measurement of the oxLDL-rich lesions developed as a result of high-fat diet-induced hyperlipidemia. Upon balloon inflation, the 2-point electrode array conformed to the arterial wall to allow deep intraplaque penetration via alternating current (AC). The frequency sweep from 10 to 300 kHz generated an increase in capacitance, providing distinct changes in both impedance (Ω) and phase (ϕ) in relation to varying degrees of intraplaque lipid burden in the aorta. Aortic endoluminal EIS measurements were compared with epicardial fat tissue and validated by intravascular ultrasound and immunohistochemistry for plaque lipids and foam cells. Thus, we demonstrate a new approach to quantify endoluminal EIS via a 2-point stretchable electrode strategy

Flexible MEA for adult zebrafish ECG recording covering both ventricle and atrium

This paper presents a flexible parylene micro-electrodearray (MEA) that records Electrocardiograms (ECG) from the Zebrafish heart in-vivo, covering both the ventricle and atrium area. ECG is a powerful tool for monitoring the heart activity. While ECG technology for human has been well established, this is not true for zebrafish. Our previous work demonstrated baseline ECG recording from zebrafish using MEMS MEAs [1, 2]. However, due to the body structure and small size of the zebrafish (e.g., the heart is roughly 1mm in size and its atrium is buried deep in the thoracic cavity, Fig.1b.), all zebrafish ECGs to date were only recorded from the ventricular side, making it easy to miss important electrophysiological signals from the atrium. To our knowledge, ECG from the atrial angles in Zebrafish has not yet been demonstrated. This work describes a flexible MEA implant (i.e., specially designed according to zebrafish heart anatomy) that records from both the ventricular and the atrial angles. Furthermore, to demonstrate that this device is useful for heart regeneration monitoring, our work also includes ECG recording before and after laser damage on the ventricle (532nm green light, 32mJ/mm^2, 20mJ total). This chosen energy level of laser pulse is first calibrated using ablated heart histology by EthD-1 florescence staining. The post injury ECG data clearly show ST-wave depression, an indication of ventricular abnormal repolarization state. In addition, repeated missing T-wave is observed from the channels recorded from the atrial angles, which indicate abnormalities in atrial physiology. A hypothesis is that since absorption coefficient of 532nm light in body tissue is rather low, the laser beam penetrated deeply in the heart and created damage deep in the atrium as well as the ventricle. The MEA presented here shows potential for an effective tool to study long-term adult zebrafish heart development and regeneration

Research on dynamic response characteristics of normal fault footwall working face and rock burst prevention technology under the influence of the gob area

Abstract To study the effect of mining dynamic response characteristics on the footwall working face of the normal fault under the influence of the gob area, theoretical research, indoor experiment, and numerical simulation are adopted to analyze the stress manifestation characteristics, overburden movement, and energy evolution characteristics during the process of mining. The results show that: (1) In the process of mining toward the fault, the working face shows the change characteristics of “stable-activation mutation-final stability”. At 20 m from the fault, the arch structure of the working face was damaged, fissures appeared near the high fault fracture zone, and the displacement of the overburden rock increased significantly; (2) the maximum value was reached at 4–8 m from the coal wall, and the superposition of tectonic stress and mining stress led to the concentration of the stress and energy accumulating on the top plate near the fault, and the data close to the gob area were even larger; (3) If the plastic damage zone of the high-level rock layer on the hanging wall and footwall of the fault appears to have a wide range of penetration, and the area formed between the shear displacement curve of the fault plane and the X-axis appears to have a significant enhancement, it is considered that the fault has been activated; (4) The size of the coal pillar of the fault is determined to be 40 m, and combined with the pressure unloading technique of the variable-diameter drilling hole, the validation is carried out through the micro-vibration monitoring, and the results of which can be used as a reference for the safety of the working face under similar conditions

Wearable flexible micro electrode for adult zebrafish long term ecgmonitoring

During the last decade, close resemblance between the zebrafish heart and human heart physiology has been discovered [1] andzebrafish (Danio rerio) has become an emerging animal model for studying side effects developmental drugs may impose on the heart [2][3]. More interestingly, contrary to human heart the zebrafish heart has a remarkable ability to “regenerate” after severe injury [4], making it also a popular model for studies of regenerative medicine. On the other hand, Electrocardiogram (ECG) is a widely used tool to monitor the physiological changes of the zebrafish heart. However, due to its in-water habitat, a long term ECG monitoring solution, although very much needed, was not present. All published adult zebrafish ECG recorded to this date have been done acutely with anesthetized fish. This work presents, for the first time a wearable flexible parylene (PA) micro-electrode that monitors the Adult Zebrafish ECG long term. We show here the design, fabrication and testing of the flexible electrode along with a micro-molded ultra-soft, density adjusted silicone jacket, allowing ECG recording to be carried under water, in the fish's natural habitat with no need for anesthesia

Spinal subdural hematoma in a patient with immune thrombocytopenic purpura following microvascular decompression: a rare case report

This article reports a case of spontaneous spinal subdural hematoma (SSDH) after brain surgery in a patient with immune thrombocytopenic purpura (ITP), reviews the relevant literature, and discusses the etiology, pathogenesis, and clinical features of SSDH in patients with ITP. A male patient in his early 50 s with an 8-year history of ITP and suffering from coexistent hemifacial spasm and trigeminal neuralgia underwent microvascular decompression in our department. His preoperative corrected platelet count was within the normal range. On postoperative day 2, the patient complained of acute low back pain and sciatica. Lumbar magnetic resonance imaging demonstrated an SSDH extending from L3 to L4 with a significantly decreased platelet count (30.0 × 10 9 /L). The pain was gradually relieved after 2 weeks of conservative treatment, and no neurological deficit occurred during the 1-year follow-up. Brain surgery may increase the risk of postoperative SSDH in patients with ITP. Clinicians planning brain surgery must conduct a rigorous assessment through detailed physical examination, laboratory tests, and medical history records and maintain perioperative platelet counts within the normal range to prevent various risks associated with spinal cord compression

Immunomodulation and signaling mechanism of Lactobacillus rhamnosus GG and its components on porcine intestinal epithelial cells stimulated by lipopolysaccharide

Background/purpose: This study aimed to evaluate the immunomodulatory effects and signaling mechanisms of Lactobacillus rhamnosus GG (LGG) and its components [surface-layer protein (SLP), DNA, exopolysaccharides, and CpG oligodeoxynucleotides] on lipopolysaccharide (LPS)-stimulated porcine intestinal epithelial cell (IEC) IPEC-J2. Methods: The mRNA expressions of inflammatory cytokines and Toll-like receptors (TLRs) were measured by quantitative real-time polymerase chain reaction. Activation of mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling was detected by western blot and immunofluorescence. Results: Pretreatment of IPEC-J2 cells with LGG, SLP, or exopolysaccharides significantly alleviated LPS-induced inflammatory cytokines and TLR activation at mRNA level. LGG, SLP, and exopolysaccharides also attenuated LPS-induced MAPK and NF-κB signaling activations. CpG oligodeoxynucleotides significantly increased the interleukin 12, tumor necrosis factor α, and TLR9 mRNA levels and enhanced NF-κB signaling activation in LPS-stimulated cells. Conclusion: LGG had immunomodulatory effects on LPS-induced porcine IECs by modulating TLR expressions and inhibiting MAPK and NF-κB signaling to decrease inflammatory cytokine expressions. Components of LGG exerted immunomodulatory effects on porcine IECs, especially immunostimulatory CpG oligodeoxynucleotides

In-vivo intravascular intervention with parylene micro-electrode to diagnose rupture-prone atherosclerotic plaque using electrical impedance spectroscopy

It is of great clinical interest to have easy and reliable diagnostic techniques to localize and identify vulnerable plaques. Here, an in-vivo, catheter-integrated and balloon-mounted Parylene-C micro electrode impedance sensor was developed for intra-vascular interrogation of atherosclerotic vulnerable plaques using Electrical Impedance spectroscopy (EIS). Successful in vivo experiments of the EIS device were demonstrated using high-fat-dieted New Zealand rabbits. The results showed that electrical impedance spectroscopy (EIS) with micro parylene electrodes is promising to distinguish unstable plaques