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: ["Protein", "Chemical"].

Please return the output as a JSON object of the format: {"Chemical" : ["Dexamethasone", ...], "Protein" : ["BRCA-1", ...]}. 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:

Toxicity of beta-amyloid in HEK293 cells expressing NR1/NR2A or NR1/NR2B N-methyl-D-aspartate receptor subunits.
Neurotoxicity induced by beta-amyloid peptide (Abeta) involves glutamate toxicity, resulting from overactivation of N-methyl-D-aspartate (NMDA) receptors and elevation of intracellular calcium. However, the heterogeneity of the NMDA receptors, frequently composed of NR1 and NR2A-D subunits, has been less studied. Thus, we determined the contribution of NMDA receptor subtypes on Abeta(1-40) toxicity in HEK293 cells transiently expressing NR1/NR2A or NR1/NR2B subunits. Analysis of lactate dehydrogenase (LDH) release and trypan blue exclusion revealed an increase in Abeta(1-40) toxicity upon NR1/NR2A expression, compared to NR1/NR2B, indicating loss of plasma membrane integrity. Furthermore, Abeta(1-40) decreased intracellular ATP in cells expressing NR1/NR2A. MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate), a noncompetitive NMDA receptor antagonist, partially prevented the decrease in cell viability and the energy impairment. These differences were not accounted for by the activation of caspases 2, 3, 8 and 9 or calpains or by DNA fragmentation, excluding the hypothesis of apoptosis. Functional NR1/NR2A and NR1/NR2B receptor subtypes were further evidenced by single-cell calcium imaging. Stimulation of NR1/NR2A receptors with NMDA/glycine revealed an increase in intracellular calcium in cells pre-exposed to Abeta(1-40). Opposite effects were observed upon activation of NR1/NR2B receptors. These results suggest that NR1/NR2A-composed NMDA receptors mediate necrotic cell death in HEK293 cells exposed to Abeta(1-40) through changes in calcium homeostasis.
{"Chemical": ["(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate", "N-methyl-D-aspartate", "glycine", "MK-801", "lactate", "NMDA", "calcium", "ATP", "glutamate", "trypan blue"], "Protein": ["NR2B", "caspases 2, 3, 8 and 9", "lactate dehydrogenase", "N-methyl-D-aspartate receptor", "LDH", "NR2A-D", "NMDA receptor", "beta-amyloid", "N-methyl-D-aspartate (NMDA) receptors", "NR1", "NMDA receptors", "beta-amyloid peptide", "NR2A", "Abeta(1-40)", "Abeta"]}