Background and Purpose: Initial reports suggest a significant risk of thrombotic events, including stroke, in patients hospitalized with coronavirus disease 2019 (COVID-19). However, there is little systematic data on stroke incidence and mechanisms, particularly in racially diverse populations in the United States. Methods: We performed a retrospective, observational study of stroke incidence and mechanisms in all patients with COVID-19 hospitalized from March 15 to May 3, 2020, at 3 Philadelphia hospitals. Results: We identified 844 hospitalized patients with COVID-19 (mean age 59 years, 52% female, 68% Black); 20 (2.4%) had confirmed ischemic stroke; and 8 (0.9%) had intracranial hemorrhage. Of the ischemic stroke patients, mean age was 64 years, with only one patient (5%) under age 50, and 80% were Black. Conventional vascular risk factors were common, with 95% of patients having a history of hypertension and 60% a history of diabetes mellitus. Median time from onset of COVID symptoms to stroke diagnosis was 21 days. Stroke mechanism was cardioembolism in 40%, small vessel disease in 5%, other determined mechanism in 20%, and cryptogenic in 35%. Of the 11 patients with complete vascular imaging, 3 (27%) had large vessel occlusion. Newly positive antiphospholipid antibodies were present in >75% of tested patients. Of the patients with intracranial hemorrhage, 5/8 (63%) were lobar intraparenchymal hemorrhages, and 3/8 (38%) were subarachnoid hemorrhage; 4/8 (50%) were on extracorporeal membrane oxygenation. Conclusions: We found a low risk of acute cerebrovascular events in patients hospitalized with COVID-19. Most patients with ischemic stroke had conventional vascular risk factors, and traditional stroke mechanisms were common.

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The coordination of activity between brain cells is a key determinant of neural circuit function; nevertheless, approaches that selectively regulate communication between two distinct cellular components of a circuit, while leaving the activity of the presynaptic brain cell undisturbed remain sparce. To address this gap, we developed a novel class of electrical synapses by selectively engineering two connexin proteins found in Morone americana (white perch fish): connexin34.7 (Cx34.7) and connexin35 (Cx35). By iteratively exploiting protein mutagenesis, a novel in vitro assay of connexin docking, and computational modeling of connexin hemichannel interactions, we uncovered the pattern of structural motifs that broadly determine connexin hemichannel docking. We then utilized this knowledge to design Cx34.7 and Cx35 hemichannels that dock with each other, but not with themselves nor other major connexins expressed in the human central nervous system. We validated these hemichannels in vivo, demonstrating that they facilitate communication between two neurons in Caenorhabditis elegans and recode a learned behavioral preference. This system can be applied to edit circuits composed by pairs of genetically defined brain cell types across multiple species. Thus, we establish a potentially translational approach, Long-term integration of Circuits using connexins (LinCx), for context-precise circuit-editing with unprecedented spatiotemporal specificity.

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