SARS-CoV-2 entry sites are present in all structural elements of the human glossopharyngeal and vagal nerves: clinical implications.

Severe acute respiratory syndrome coronavirus (SARS-CoV-2) infections result in the temporary loss of smell and taste (anosmia and dysgeusia) in about one third of confirmed cases. Several investigators have reported that the viral spike protein receptor is present in olfactory neurons. However, no study has been published to date showing the presence of viral entry sites angiotensin-converting enzyme 2 (ACE2), neuropilin1 (NRP1), and TMPRSS2, the serine protease necessary for priming the viral proteins, in human nerves that are responsible for taste sensation (cranial nerves: VII, IX and X). We used immunocytochemistry to examine three postmortem donor samples of the IXth (glossopharyngeal) and Xth (vagal) cranial nerves where they leave/join the medulla from three donors to confirm the presence of ACE2, NRP1 and TMPRSS2. Two samples were paraffin embedded; one was a frozen sample. In addition to staining sections from the latter, we isolated RNA from it, made cDNA, and performed PCR to confirm the presence of the mRNAs that encode the proteins visualized. All three of the proteins required for SARS-CoV-2 infections appear to be present in the human IXth and Xth nerves near the medulla. Direct infection of these nerves by the COVID-19 virus is likely to cause the loss of taste experienced by many patients. In addition, potential viral spread through these nerves into the adjacent brainstem respiratory centers might also aggravate the respiratory problems patients are experiencing.

Laparoscopy--a stressful procedure.

The metabolic and hormonal response to laparoscopy was investigated in 22 patients, in whom nitrous oxide-oxygen anaesthesia was supplemented with either 150 micrograms fentanyl or an Althesin infusion. There were significant increases in plasma cortisol (p less than 0.05) from 303 to 458 mmol/litre and prolactin from 1869 to 3918 mU/litre (p less than 0.01) at the end of laparoscopy in both groups of patients; these were sustained during the first hour of the recovery period. The blood glucose concentration increased significantly (p less than 0.05) from 4.48 to 5.28 mmol/litre at the end of laparoscopy in the Althesin patients and remained increased 1 hour postoperatively at 5.54 mmol/litre (p less than 0.01). The blood glucose concentration increased significantly (p less than 0.05) from 4.43 to 5.36 mmol/litre in the fentanyl patients only during the recovery period. There was no significant difference between the metabolic and hormonal changes observed with the two anaesthetic techniques.