The aim of this study was to investigate the causation of an insufficient clinical response to acute external stimulation after implantation of brain stimulating electrodes in patients with idiopathic Parkinson's disease (IPD). This study represents to our knowledge the first consecutive postoperative monitoring of the electrical properties of electrodes and tissue in this patient cohort. We hypothesized that changes in brain tissue resistance would be etiologic for this clinically observed phenomenon. Eight patients with IPD were monitored over a fixed time course (day 1-7). The voltage drop on the electrodes and in the tissue was measured. Our measurements indicate a significant inhomogeneity of the surrounding tissue and a marked interpatient difference of the electrode voltage drop. The changes of the voltage drop on the electrodes and the tissue were insignificant over the time course. We conclude that the decline of the clinical benefit is not due to an alteration of tissue resistivity. As an explanation, we postulate that the reactive formation/resolution of edema around the electrode has the same resistivity as the target and is therefore not detectable by our measurements or modulated by a still unknown mechanism.
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http://dx.doi.org/10.1046/j.1525-1403.2003.03032.x | DOI Listing |
Sensors (Basel)
January 2025
Department of Mechanical Engineering, Politecnico di Milano, Via Giuseppe La Masa 1, 20156 Milan, Italy.
Radiofrequency ablation (RFA) is a minimally invasive procedure that utilizes localized heat to treat tumors by inducing localized tissue thermal damage. The present study aimed to evaluate the temperature evolution and spatial distribution, ablation size, and reproducibility of ablation zones in ex vivo liver, kidney, and lung using a commercial device, i.e.
View Article and Find Full Text PDFEpithelial tissues in vitro undergo dynamic changes while differentiating heterogeneously on the culture substrate. This gives rise to diverse cellular arrangements which are undistinguished by conventional analysis approaches, such as transepithelial electrical resistance measurement or permeability assays. In this context, solid substrate-based systems with integrated electrodes and electrochemical impedance monitoring capability can address the limited spatiotemporal resolution of traditional porous membrane-based methods.
View Article and Find Full Text PDFChaos
January 2025
School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China.
Arrhythmia of the heart is a dangerous and potentially fatal condition. The current widely used treatment is the implantable cardioverter defibrillator (ICD), but it is invasive and affects the patient's quality of life. The sonogenetic mechanism proposed here focuses ultrasound on a cardiac tissue, controls endogenous stretch-activated Piezo1 ion channels on the focal region's cardiomyocyte sarcolemma, and restores normal heart rhythm.
View Article and Find Full Text PDFBiosens Bioelectron
January 2025
Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, 213164, Changzhou, China. Electronic address:
Wearable sensors can easily enable real-time and noninvasive glucose (Glu) monitoring, providing vital information for effectively preventing various complications caused by high glucose level. Here, a wearable sensor based on nanozyme-catalyzed cascade reactions is designed for Glu monitoring in sweat. Au nanoparticles (AuNPs) are anchored to the carbonated zeolitic imidazolate framework-8 (ZIF-8-C), endowing the sensor with Glu oxidase (GOx)-like and peroxidase (POD)-like activity.
View Article and Find Full Text PDFJ Neural Eng
January 2025
Department of Physiology and Department of Electrical and Computer System Engineering, Monash University - Clayton Campus, Wellington Rd, Melbourne, Victoria, 3800, AUSTRALIA.
Development of cortical visual prostheses requires optimization of evoked responses to electrical stimulation to reduce charge requirements and improve safety, efficiency, and efficacy. One promising approach is timing stimulation to the local field potential (LFP), where action potentials have been found to occur preferentially at specific phases. To assess the relationship between electrical stimulation and the phase of the LFP, we recorded action potentials from primary (V1) and secondary (V2) visual cortex in marmosets while delivering single-pulse electrical microstimulation at different phases of the local field potential.
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