You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

First-time-in-human study with GSK249320, a myelin-associated glycoprotein inhibitor, in healthy volunteers. GSK249320, a monoclonal antibody directed against myelin-associated glycoprotein (MAG), is being developed for the enhancement of recovery of function poststroke. Potential safety concerns of adverse effects on myelin led to the inclusion of pharmacodynamic measures of peripheral and central neuronal function in this first-time-in-human (FTIH) study. The study also evaluated general safety, pharmacokinetics, and immunogenicity of GSK249320. Single intravenous infusions of GSK249320 (0.04, 0.4, 1.2, 3.5, 10, and 25 mg/kg) or placebo were administered to 47 healthy subjects aged 18-60 years. GSK249320 was well tolerated at all doses. No clinically significant abnormalities were observed in neurological examinations, nerve conduction tests (NCTs), quantitative sensory tests (QSTs), clinical laboratory tests, or electrocardiograms. There were no severe or serious adverse events. GSK249320 had a half-life (HL) of 21 days and a volume of distribution at steady state of 45.8 ml/kg, with AUC showing dose linearity. GSK249320 did not induce antidrug antibodies.
{"Chemical": []}