"Effects of Acoustic Waves on Microtubules and Cells" by Jack Tuszynski

Quick Overview

Acoustic waves, specifically ultrasound, interact with the mechanical structures within cells, like microtubules, causing observable effects such as arresting cancer cells in mitosis when applied at resonant or specific frequencies, although high frequencies, up to 500 MHz in theoretical models, are needed for complete microtubule destruction.

Key Points: Ultrasound frequencies used in medical applications typically range from 75 kHz to 3.3 MHz, interacting with cellular mechanics through thermal and non-thermal effects. The speaker noted that early experiments demonstrated ultrasound could arrest cancer cells in mitosis and cited a 2005 paper showing clinical utility in pancreatic cancer patients. Microtubules are the most rigid structures in the cell, acting as compression-resistant components, while actin filaments are tension-resistant, forming a system described by Tensegrity theory. Theoretical modeling showed that for a single microtubule, harmonics N=67 and higher would be underdamped, while lower harmonics would be overdamped, with the first underdamped case estimated at 500 MHz. Experimental exposure of stabilized microtubules (tubulin in buffer) to ultrasound up to 2 MHz for 1-2 hours caused them to break up and disassemble. Later experiments using Fibonacci sequences of pulses on yeast, Ha (algae), and Chlorella (green algae) showed differential cell viability based on frequency, with the lowest viability for Ha occurring at 127 Hz. The speaker emphasized that the mechanical response of cytoskeletal structures is frequency-dependent; rapid stimulation may result in underdamped oscillation before energy dissipates into the viscous solution.

Context: Jack Tuszynski discusses the mechanical aspects of living cells, focusing on how acoustic waves, particularly ultrasound, affect internal structures like microtubules. The presentation begins with basic concepts of mechanical resonance, the structural stability of cells under Tensegrity theory, and delves into specific mechanics of microtubules, illustrated by experiments involving ultrasound exposure on both isolated microtubules and synchronized cancer cells (HeLa and BO cells).