Biology subjects

Badawe, H.

Publications and source records attributed to Badawe, H..

3 recordsLinked to original sources

bioRxiv2024

Modulating Peripheral Neural Activity: Prolonged Low-Intensity Ultrasound for Controlled Excitation and Suppression in Rat Sciatic Nerve

ObjectiveLow-intensity, low-frequency ultrasound has shown promise for neuromodulation, particularly for influencing peripheral neural activity. However, the precise parameters required to modulate neuronal activity consistently remain poorly understood, limiting its broader application. Here, we investigate the effects of varying sonication duration (SD) and duty cycle (DC) on motor neuronal responses in the rat sciatic nerve, focusing on understanding how cumulative energy exposure influences the activation, enhancement, or suppression of peripheral neural activity during ultrasound neuromodulation. ApproachWe apply low-intensity, low-frequency ultrasound to the rat sciatic nerve in vivo at different sonication durations (30s, 60s, 90s, and 120s) and duty cycles (30%, 50%, and 80%). The cumulative energy exposure is calculated as the product of spatial-peak pulse-average intensity, SD, and DC. Electromyographic (EMG) activity in the gastrocnemius muscle is measured, and the thermal effects are monitored to ensure a non-cavitational, non-thermal application. Main ResultsOur findings demonstrate that higher cumulative energy exposures suppress EMG activity in the gastrocnemius muscle (enervated by the sciatic nerve). However, lower cumulative energy exposures enhance EMG activity and motor stimulation. Notably, the ultrasound-induced EMG changes persisted for 5 minutes post-sonication - three to five times longer than the application duration -- underscoring the therapeutic potential of ultrasound for precise neural control. In vivo evaluations suggest the mechanical nature of the observed effects without any significant temperature increase or induction of cavitation. In vivo evaluations suggest the mechanical nature of the observed effects without any significant temperature increase or induction of cavitation. SignificanceInterestingly, our results show a switch from excitation to suppression of electrically evoked EMG activity following ultrasound sonication depending on the acquired cumulative energy. This study establishes a safe parameter space for prolonged neuromodulation, demonstrating its potential for therapeutic applications that can precisely modulate peripheral nervous system activity. These findings contribute to the development of ultrasound-based treatments for neurological conditions, offering a novel and controllable method for peripheral nerve stimulation.

bioengineering↗

bioRxiv2023

HIFU Thermal Ablation in Breast Cancer Cells: Monolayers vs. Spheroids

ObjectiveThe primary objective of our study was to investigate the efficiency of high intensity focused ultrasound (HIFU) ablation in two distinct cellular configurations, 2D monolayers and 3D spheroids of epithelial breast cancer cell lines. The study also compares empirical findings from experiments with results obtained through numerical simulations using a bioheat computational model. This comparison is intended to provide a comprehensive understanding of the acoustic energy conversion within the biological system during HIFU treatment. MethodsHIFU was applied to 2D and 3D cultured MDA-MB 231 and MCF7 epithelial breast cancer cell lines while systematically varying ultrasound intensity and duty cycle (DC) during sonication sessions of different durations. Temperature elevation was measured and the ablation percentage was calculated based on bright field and fluorescent imaging of the treated regions. Experimental results were validated through simulations of the ablation setup. ResultsUpon HIFU, spheroids exhibited a lower temperature increase (approximately 20 {degrees}C) when subjected to comparable acoustic intensities and duty cycles. The level of tumor ablation was highly influenced by DC, with higher DCs leading to greater ablation percentages. However, sonication duration had a minimal impact on the degree of ablation. Numerical simulations corroborated these observations, demonstrating uniform heat distribution within the cultured cells. At higher DCs and intensities, complete ablation of spheroids was achieved, whereas at lower levels, only the outermost layers exhibited ablation. ConclusionOur study reveals a significant disparity in the response of 2D monolayers and 3D spheroids to HIFU treatment. Specifically, tumor spheroids require lower temperature elevations for effective ablation, and their ablation percentage significantly increases with elevated DC.

bioengineering↗

bioRxiv2023

High Resolution Acoustic Mapping of Gelatin-Based Soft Tissue Phantoms

BackgroundUtilizing spatially and temporally uniform tissue-mimicking phantoms for ultrasonic applications can facilitate the characterization of beam distortion and attenuation. The implementation of acoustic phantoms can enhance the efficacy of ultrasound therapy or imaging by providing guidance on optimal ultrasonic parameters, such as frequency and power. The efficacy of phantoms is heavily dependent on the accuracy and reliability of measurement techniques employed for assessing their acoustic properties. PurposeThe work aims to develop, build, and characterize, via high resolution acoustic mapping, Gelatin-Based ultrasound (US) soft tissue phantoms. To that effect, we built acoustic maps of the intensity distribution of US waves passing through the phantoms and studied the effect of gelatin concentrations and US frequency, duty cycle, and applied voltage on the acoustic intensity and focal region of the US waves. The methodology developed here offers well characterized and reproducible Gelatin-Based US phantoms for soft tissue (both acoustically and mechanically). MethodsWe developed gelatin-based phantoms, with conveniently adjustable parameters and measured, with high resolution, the acoustic attenuation of ultrasound waves when encountering the gelatin phantoms. This was done via a motorized acoustic system built for 3D-acoustic mapping of ultrasound waves. Mechanical assessment of the phantoms elasticity was carried out through unconfined compression tests. We characterized tissue mimicking phantoms with realistic acoustic properties and mechanical elasticity, emphasizing the effect of varying gelatin concentration on the ultrasound maximal intensity, thus causing acoustic attenuation throughout the acoustic profile. For validation, we used computational simulations to compare our data to predicted acoustical outcomes. ResultsOur results show high-resolution mapping of US waves in fluid with and without Gelatin-Based phantoms. We also confirm the impact of recipe and gelatin concentration on mechanical and acoustic characterization of phantoms. The density of the gelatin-based phantoms scales with the Youngs modulus. When characterizing the acoustic profiles of the different ultrasound transducers, the focal areas increased systematically as a function of increasing applied voltage and duty cycle yet decreased as a function of increased ultrasonic frequency. ConclusionsWe developed a Gelatin-Based US phantoms are a reliable and reproduce tool for examining the acoustic attenuations taking place as a function of increased tissue elasticity and stiffness. High resolution acoustic maps of the intensity distribution of US can provide essential information on the spatial changes in US wave intensity and focal point enabling a more in-depth examination of the effect of tissue on US waves.

biophysics↗