NMOSD: Previously Seropositive Patient Presents with Seronegative Brainstem Attack (P11-14.017).

Objective: Describe a patient with prior AQP4-IgG seropositivity with a new brainstem attack in the absence of detectable AQP4-IgG.

Background: Neuromyelitis optica spectrum disorder (NMOSD) is associated with antibodies directed against aquaporin 4 (AQP4-IgG) resulting in attacks of optic neuritis, longitudinally extensive transverse myelitis (LETM), or area postrema syndrome. Symptoms may present simultaneously or asynchronously.

Role of Heterogeneous Reactions in the Atmospheric Oxidizing Capacity in Island Environments.

The source of nitrous acid (HONO) and its importance in island or marine environments are poorly understood. Herein, based on comprehensive field measurements at a hilltop on Corsica Island, we find an inverse diel variation of HONO with higher concentrations during daytime. Night-time HONO budget analysis indicates significant HONO formation during air mass transport along the hillside.