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:

Plasma S/R ratio of warfarin co-varies with VKORC1 haplotype.
We recently reported that the low-dose VKORC1*2 haplotype is an important genetic determinant for warfarin dose requirement and is associated with difficulties to attain stable therapeutic prothrombin time--International Normalized Ratio in patients undergoing anticoagulation therapy. The aim of this study was to investigate whether patients with VKORC1*2 compared with patients carrying high-dose haplotypes VKORC1*3 or VKORC1*4 had different warfarin S/R ratios in their plasma, and whether that was related to CYP2C9 variants CYP2C9*2 and CYP2C9*3 or other factors. Samples from patients previously haplotyped for VKORC1 and measured for plasma warfarin concentration were genotyped for the CYP2C9 variants CYP2C9*2 and CYP2C9*3. Nonparametric statistical analysis was performed to elucidate whether there was any significant difference in the warfarin S/R ratio between the two patient groups. Our result shows that there is a significant difference (P<0.01) in warfarin S/R ratios between VKORC1*2 and VKORC1*3 or VKORC1*4 patients. This difference did not originate from CYP2C9 variants CYP2C9*2 and CYP2C9*3. We speculate that VKORC1 haplotypes possibly are linked to some unidentified factors involved in the metabolic clearance of warfarin enantiomers. Dose-dependent variations in (S)-warfarin and (R)-warfarin clearance in these patients can also be a probable explanation for the difference in warfarin S/R ratios.
{"Chemical": ["warfarin S/R", "(R)-warfarin", "(S)-warfarin", "warfarin"], "Protein": ["prothrombin", "CYP2C9", "VKORC1"]}