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:

Free fatty acid binding protein-4 and retinol binding protein-4 in polycystic ovary syndrome: response to simvastatin and metformin therapies. Abstract Free fatty acid binding protein-4 (FABP4) and retinol binding protein-4 (RBP4) contribute to metabolic syndrome. We investigated serum FABP4 and RBP4 responses to insulin sensitizing and lipid lowering therapies in polycystic ovary syndrome (PCOS). Sixty-two healthy, untreated women with PCOS (age 25.1 ± 3.6 years, BMI: 24.0 ± 4.7 kg/m(2)) were randomized to metformin (n = 24), simvastatin (n = 20) or metformin plus simvastatin (n = 18) for 3 months. Anthropometric measures, fasting blood tests and oral glucose tolerance tests (OGTT) were obtained at the baseline and the end. At the baseline serum FABP4 correlated with obesity (BMI: r = 0.63, p < 0.001), insulin resistance (fasting insulin: r = 0.44, p = 0.0002; QUICKI: r = -0.30, p = 0.02; OGTT-insulin sensitivity index: r = -0.27, p = 0.04), dyslipidemia (HDL: r = -0.26, p = 0.03) and hyperandrogenemia (free-testosterone: r = 0.23, p = 0.03; SHBG: r = -0.28, p = 0.03); while RBP4 correlated with total-cholesterol (r = 0.33, p = 0.009). Multiple regression analysis indicated that t best predictors of serum FABP4 and RBP4 were BMI (β = 1.02, p = 0.0003) and total cholesterol (β = 2326, p = 0.01), respectively. Simvastatin, alone or with metformin did not affect serum FABP4 or RBP4. Serum FABP4 related to the obesity, insulin resistance and inflammation while RBP4 related to lipids. Insulin sensitizing and lipid lowering therapies did not affect FABP4 or RBP4 levels in PCOS.
{"Chemical": ["metformin", "glucose", "retinol", "cholesterol", "simvastatin", "fatty acid", "Simvastatin"]}