Background: A novel coronavirus disease in Wuhan has caused an outbreak and become a major public health issue in China and great concern from international community. Myocarditis and myocardial injury were suspected and may even be considered as one of the leading causes for death of COVID-19 patients. Therefore, we focused on the condition of the heart, and sought to provide firsthand evidence for whether myocarditis and myocardial injury were caused by COVID-19. Methods: We enrolled patients with confirmed diagnosis of COVID-19 retrospectively and collected heart-related clinical data, mainly including cardiac imaging findings, laboratory results and clinical outcomes. Serial tests of cardiac markers were traced for the analysis of potential myocardial injury/myocarditis. Results: 112 COVID-19 patients were enrolled in our study. There was evidence of myocardial injury in COVID-19 patients and 14 (12.5%) patients had presented abnormalities similar to myocarditis. Most of patients had normal levels of troponin at admission, that in 42 (37.5%) patients increased during hospitalization, especially in those that died. Troponin levels were significantly increased in the week preceding the death. 15 (13.4%) patients have presented signs of pulmonary hypertension. Typical signs of myocarditis were absent on echocardiography and electrocardiogram. Conclusions: The clinical evidence in our study suggested that myocardial injury is more likely related to systemic consequences rather than direct damage by the 2019 novel coronavirus. The elevation in cardiac markers was probably due to secondary and systemic consequences and can be considered as the warning sign for recent adverse clinical outcomes of the patients.

Axon-derived molecules are temporally and spatially required as positive or negative signals to coordinate oligodendrocyte differentiation. Increasing evidence suggests that, in addition to the inhibitory Jagged1/Notch1 signaling cascade, other pathways act via Notch to mediate oligodendrocyte differentiation. The GPI-linked neural cell recognition molecule F3/contactin is clustered during development at the paranodal region, a vital site for axoglial interaction. Here, we show that F3/contactin acts as a functional ligand of Notch. This trans-extracellular interaction triggers gamma-secretase-dependent nuclear translocation of the Notch intracellular domain. F3/Notch signaling promotes oligodendrocyte precursor cell differentiation and upregulates the myelin-related protein MAG in OLN-93 cells. This can be blocked by dominant negative Notch1, Notch2, and two Deltex1 mutants lacking the RING-H2 finger motif, but not by dominant-negative RBP-J or Hes1 antisense oligonucleotides. Expression of constitutively active Notch1 or Notch2 does not upregulate MAG. Thus, F3/contactin specifically initiates a Notch/Deltex1 signaling pathway that promotes oligodendrocyte maturation and myelination.

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Deletion of phenylalanine at position 508 (⌬F508) is the most common cystic fibrosis (CF)-associated mutation in the CF transmembrane conductance regulator (CFTR), a cAMP-regulated chloride channel. The consensus notion is that ⌬F508 imposes a temperature-sensitive folding defect and targets newly synthesized CFTR for degradation at endoplasmic reticulum (ER). A limited amount of CFTR activity, however, appears at the cell surface in the epithelia of homozygous ⌬F508 CFTR mice and patients, suggesting that the ER retention is not absolute in native tissues. To further elucidate the reasons behind the inability of ⌬F508 CFTR to accumulate at the plasma membrane, its stability was determined subsequent to escape from the ER, induced by reduced temperature and glycerol. Biochemical and functional measurements show that rescued ⌬F508 CFTR has a temperature-sensitive stability defect in post-ER compartments, including the cell surface. The more than 4 -20-fold accelerated degradation rate between 37 and 40°C is, most likely, due to decreased conformational stability of the rescued ⌬F508 CFTR, demonstrated by in situ protease susceptibility and SDS-resistant thermoaggregation assays. We propose that the decreased stability of the spontaneously or pharmacologically rescued mutant may contribute to its inability to accumulate at the cell surface. Thus, therapeutic efforts to correct the folding defect should be combined with stabilization of the native ⌬F508 CFTR.