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Coronavirus disease 2019 (COVID-19) is an emerging infectious disease caused by a newly discovered coronavirus that has reached pandemic proportions impacting millions globally. Authors feature an atypical case of COVID-19 presenting with a rare cause of abdominal pain and severe hyperglycemia. A 22-year-old male presented to the hospital with a 1-day history of severe abdominal pain. An abdominal computed tomography (CT) scan revealed findings of epiploic appendagitis (EA) and incidentally noted suspicious pulmonary lesions suggestive of COVID-19. Radiographic findings and distinctive laboratory results led to prompt testing by nasopharyngeal polymerase chain reaction (PCR), which ultimately confirmed the proposed diagnosis. Additionally, a significantly elevated hemoglobin A1c (HbA1c) signified undiagnosed diabetes mellitus. The patient was treated conservatively with supportive measures and made a full recovery. To our knowledge, this is the first case to describe how EA, a rare cause of abdominal pain, indirectly led to the diagnosis of COVID-19.

Development of peptidomimetic helical foldamers with a wide repertoire of functions is of significant interest. Herein, for the first time, we report the X-ray crystal structures of a series of homogeneous L-sulfono-γ-AA foldamers, and elucidate their folding conformation at the atomic level. Single crystal X-ray crystallography reveals that this class of oligomers fold into unprecedented dragon-boat-shaped and surprisingly unexpected left-handed helices, which are stabilized by the 14-hydrogen bonding pattern unanimously present in the sequences. With a helical pitch of 5.1 Å and exactly four side chains per turn, these L-sulfono-γ-AApeptides bear side chains which lie perfectly on top of each other along the helical axis. The 2D-NMR, computational simulation and CD studies consistently support the folding conformation in solution. Our results provide a structural basis at the atomic level for the design of novel biomimetics with precise arrangement of functional groups in three dimensions, which is envisaged to lead to the development of foldamers with unique biomimetic scaffold and new functions.

The confinement method is a robust and conceptually simple free energy simulation method that allows the calculation of conformational free energy differences between highly dissimilar states. Appl...