Epileptic encephalopathies, including Dravet syndrome, are severe treatment-resistant epilepsies with developmental regression. We examined a mouse model based on a human β1 sodium channel subunit (Scn1b) mutation. Homozygous mutant mice shared phenotypic features and pharmaco-sensitivity with Dravet syndrome. Patch-clamp analysis showed that mutant subicular and layer 2/3 pyramidal neurons had increased action potential firing rates, presumably as a consequence of their increased input resistance. These changes were not seen in L5 or CA1 pyramidal neurons. This raised the concept of a regional seizure mechanism that was supported by data showing increased spontaneous synaptic activity in the subiculum but not CA1. Importantly, no changes in firing or synaptic properties of gamma-aminobutyric acidergic interneurons from mutant mice were observed, which is in contrast with Scn1a-based models of Dravet syndrome. Morphological analysis of subicular pyramidal neurons revealed reduced dendritic arborization. The antiepileptic drug retigabine, a K+ channel opener that reduces input resistance, dampened action potential firing and protected mutant mice from thermal seizures. These results suggest a novel mechanism of disease genesis in genetic epilepsy and demonstrate an effective mechanism-based treatment of the disease.

Highlights Angiotensin converting enzyme (ACE) genotypes may influence COVID-19 mortality. II genotype frequency was significantly associated with decreased mortality. Association between increased mortality and DD genotype frequency was not detected.

Relapsing polychondritis is a rare autoimmune condition characterized by episodic and progressive cartilaginous inflammation. Its clinical presentation is vastly divergent and can affect various organs. We report the uncommon case of large airway involvement in a patient presenting with shortness of breath on the background of diagnosed relapsing polychondritis. Computed tomography (CT) chest demonstrated thickening of the cartilaginous portions of the trachea and bronchi with sparing of the posterior membranes, consistent with tracheobronchomalacia and repeated cartilaginous destruction. High doses of systemic glucocorticoids, accompanied by continuous positive airway pressure, were required for treatment. We highlight the importance of identifying the extent of airways affected and definitive positive airway pressure support for relapsing polychondritis affecting major airways in addition to conventional therapy of immunosuppression.

No abstract