Douglas, Vanja C.

The Neurohospitalist Core Competencies comprise a set of competency-based learning objectives that encapsulate the knowledge, skills, and attitudes of neurohospitalitists who specialize in the care of hospitalized patients with neurologic conditions. These competencies serve to characterize the rapidly expanding field of neurohospitalist medicine. The 27 chapters are divided into 3 sections entitled: neurological conditions, clinical interventions and interpretation of ancillary studies, and neurohospitalist role in the healthcare system. Each individual learning objective in the chapters describes a specific concept with an action verb to illustrate the behavior that the neurohospitalist exhibits. The individual neurohospitalist may not exhibit mastery in each of the topics included as individual practices vary in scope and practice pattern. A few examples of how the complete set of competencies may be used include in the creation of curricula for neurohospitalist fellowships, to assist in defining the scope of practice of neurohospitalists for administrative leaders of hospitals and departments, and in influencing the direction of further research and quality improvement in the field.

Vitamin B12 is critical for hematopoiesis and myelination. Deficiency can cause neurologic deficits including loss of coordination and cognitive decline. However, diagnosis relies on measurement of vitamin B12 in the blood, which may not accurately reflect the concentration in the brain. Using programmable phage display, we identified an autoantibody targeting the transcobalamin receptor (CD320) in a patient with progressive tremor, ataxia, and scanning speech. Anti-CD320 impaired cellular uptake of cobalamin (B12) in vitro by depleting its target from the cell surface. Despite a normal serum concentration, B12 was nearly undetectable in her cerebrospinal fluid (CSF). Immunosuppressive treatment and high-dose systemic B12 supplementation were associated with increased B12 in the CSF and clinical improvement. Optofluidic screening enabled isolation of a patient-derived monoclonal antibody that impaired B12 transport across an in vitro model of the blood-brain barrier (BBB). Autoantibodies targeting the same epitope of CD320 were identified in seven other patients with neurologic deficits of unknown etiology, 6% of healthy controls, and 21.4% of a cohort of patients with neuropsychiatric lupus. In 132 paired serum and CSF samples, detection of anti-CD320 in the blood predicted B12 deficiency in the brain. However, these individuals did not display any hematologic signs of B12 deficiency despite systemic CD320 impairment. Using a genome-wide CRISPR screen, we found that the low-density lipoprotein receptor serves as an alternative B12 uptake pathway in hematopoietic cells. These findings dissect the tissue specificity of B12 transport and elucidate an autoimmune neurologic condition that may be amenable to immunomodulatory treatment and nutritional supplementation.