title: Higher impact energy in traumatic brain injury interferes with noncovalent and covalent bonds resulting in cytotoxic brain tissue edema as measured with computational simulation.
abstract: BACKGROUND
  Cytotoxic brain tissue edema is a complicated secondary consequence of ischemic injury following cerebral diseases such as traumatic brain injury and stroke. To some extent the pathophysiological mechanisms are known, but far from completely. In this study, a hypothesis is proposed in which protein unfolding and perturbation of nucleotide structures participate in the development of cytotoxic edema following traumatic brain injury (TBI).
  
  
  METHODS
  An advanced computational simulation model of the human head was used to simulate TBI. The consequences of kinetic energy transfer following an external dynamic impact were analyzed including the intracranial pressure (ICP), strain level, and their potential influences on the noncovalent and covalent bonds in folded protein structures.
  
  
  RESULTS
  The result shows that although most of the transferred kinetic energy is absorbed in the skin and three bone layers, there is a substantial amount of energy reaching the gray and white matter. The kinetic energy from an external dynamic impact has the theoretical potential to interfere not only with noncovalent but also covalent bonds when high enough. The induced mechanical strain and pressure may further interfere with the proteins, which accumulate water molecules into the interior of the hydrophobic structures of unfolded proteins. Simultaneously, the noncovalent energy-rich bonds in nucleotide adenosine-triphosphates may be perturbed as well.
  
  
  CONCLUSIONS
  Based on the analysis of the numerical simulation data, the kinetic energy from an external dynamic impact has the theoretical potential to interfere not only with noncovalent, but also with covalent bonds when high enough. The subsequent attraction of increased water molecules into the unfolded protein structures and disruption of adenosine-triphosphate bonds could to some extent explain the etiology to cytotoxic edema.
authors: Section of Neurosurgery, Division of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden, hans.von.holst@ki.se.
authors: Hans
authors: H
authors: von Holst
authors: Xiaogai
authors: X
authors: Li
mesh_terms: D001921:Brain / Q000503:physiopathology*; D001929:Brain Edema / Q000209:etiology* / Q000503:physiopathology; D001930:Brain Injuries / Q000150:complications* / Q000503:physiopathology; D003198:Computer Simulation; D006257:Head; D006801:Humans; D007427:Intracranial Pressure; D008953:Models, Anatomic