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Proteina C, o protează serinică dependentă de vitamina K, sintetizată in hepatocite ca zimogen inactiv, se activează sub acţiunea trombinei în complex cu trombomodulina endotelială. Un receptor endotelial al proteinei C (EPCR) intervine atât în activarea cât şi în optimizarea activităţii proteinei C activate având ca efect degradarea proteolitică a factorilor coagulării Va şi VIIIa şi exercitând astfel un eficient efect anticoagulant. S-a dovedit că citokinele proinflamatorii perturbă activarea la nivel endotelial inducând internalizarea şi degradarea trombomodulinei şi indepărtând EPCR de la suprafaţa celulelor endoteliale. Cercetări clinice şi experimentale au demonstrat că reacţia de fază acută se asociază cu o comutare a sintezei hepatice de proteine ducând la creşterea fibrinogenemiei, a factorului VIII:C şi a nivelului de α1 inhibitor al proteazelor, în timp ce sinteza de zimogen a proteinei C se reduce. Pe de altă parte, infuziile de proteina C activată protejează faţă de şocul toxico-septic exercitând nu doar efecte anticoagulante, dar şi o activitate antiinflamatorie.

Background: Magnetic resonance imaging (MRI) is the gold standard in the etiological assessment of a persistent olfactory dysfunction (OD). While the utility of imaging in COVID‐19‐related OD has yet to be established, MRI is recommended in all patients with persistent OD. The high prevalence of the latter after SARS‐CoV‐2 infection means evaluating this strategy is an important public health matter. Methods: The main objective was to examine the impact of systematic MRI on the management of patients with OD. All adult patients consulting for persistent OD (>2 months) after primary SARS‐COV‐2 infection (PCR) between March 2020 and December 2021 were included (n = 67). The secondary objective was to evaluate the relationship between the severity of the OD as measured by psychophysical testing (ETOC) and the volume of the olfactory bulb (OB) measured by MRI. Results: All patients underwent MRI, and none led to a change in diagnosis or treatment. Among them, 82% (55/67) were considered normal by the radiologist on initial interpretation. There were no significant differences (visual analysis or OB volume) between groups (mild, moderate, and severe hyposmia). Conclusion: Systematic MRI may be unnecessary in patients whose persistent OD began soon (a few days) after confirmed SARS‐CoV‐2 infection. [ABSTRACT FROM AUTHOR]