title: A viscoelastic model for axonal microtubule rupture.
abstract: Axon is an important part of the neuronal cells and axonal microtubules are bundles in axons. In axons, microtubules are coated with microtubule-associated protein tau, a natively unfolded filamentous protein in the central nervous system. These proteins are responsible for cross-linking axonal microtubule bundles. Through complimentary dimerization with other tau proteins, bridges are formed between nearby microtubules creating bundles. Formation of bundles of microtubules causes their transverse reinforcement and has been shown to enhance their ability to bear compressive loads. Though microtubules are conventionally regarded as bearing compressive loads, in certain circumstances during traumatic brain injuries, they are placed in tension. In our model, microtubule bundles were formed from a large number of discrete masses. We employed Standard Linear Solid model (SLS), a viscoelastic model, to computationally simulate microtubules. In this study, we investigated the dynamic responses of two dimensional axonal microtubules under suddenly applied end forces by implementing discrete masses connected to their neighboring masses with a Standard Linear Solid unit. We also investigated the effect of the applied force rate and magnitude on the deformation of bundles. Under tension, a microtubule fiber may rupture as a result of a sudden force. Using the developed model, we could predict the critical regions of the axonal microtubule bundles in the presence of varying end forces. We finally analyzed the nature of microtubular failure under varying mechanical stresses.
authors.affiliation: Center of Excellence in Energy Conversion (CEEC), School of Mechanical Engineering, Sharif University of Technology, P.O. Box 11155-9567, Tehran, Iran; Institute for Research in Fundamental Sciences, Tehran, Iran. Electronic address: shamloo@sharif.edu.
authors.forename: Amir
authors.initials: A
authors.lastname: Shamloo
authors.affiliation: Center of Excellence in Energy Conversion (CEEC), School of Mechanical Engineering, Sharif University of Technology, P.O. Box 11155-9567, Tehran, Iran.
authors.forename: Farid
authors.initials: F
authors.lastname: Manuchehrfar
authors.affiliation: Institute for Research in Fundamental Sciences, Tehran, Iran.
authors.forename: Hashem
authors.initials: H
authors.lastname: Rafii-Tabar
mesh_terms: D001369:Axons / Q000378:metabolism*; D019245:Compressive Strength; D003599:Cytoskeleton / Q000378:metabolism; D004548:Elasticity; D006801:Humans; D008870:Microtubules / Q000378:metabolism*; D008962:Models, Theoretical; D055503:Protein Multimerization; D013314:Stress, Mechanical; D014783:Viscosity; D016875:tau Proteins / Q000737:chemistry*
chemical_list: D016875:tau Proteins
keywords: Axon; Microtubule; Rupture; Standard Linear Solid; Viscoelastic