ACE2 and COVID-19: The highest ACE2 expression level was detected in the brainstem containing the medullary respiratory centers, an observation that could be relevant to the respiratory distress experienced by many COVID-19 patients.160 Upregulation of ACE2 in the brain has been linked to oxidative stress, apoptosis, and neuroinflammation leading to neurodegeneration in several brain disorders.161 Consistent with this possibility, a post-mortem case report detected SARS-CoV-2 viral particles in endothelial cells of the microvasculature of the frontal lobes.162