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:

NTproBNP: An Important Biomarker in Cardiac Diseases. Natriuretic neuropeptides (ANP, BNP, CNP) are produced primarily in the cardiac atria under normal conditions. The main stimulus for ANP and BNP peptide synthesis and secretion is cardiac wall stress. Cardiac ventricular myocytes constitute the major source of BNP-related peptides. Ventricular NT-proBNP production is upregulated in cardiac failure and locally in the area surrounding a myocardial infarct. NT-proBNP is cleared passively by organs with high rate of blood flow (muscle, liver, kidney). It has a longer half life than BNP and higher plasma concentration. BNP and NTproBNP tend to be higher in women and lower in obese individuals. They are also higher in elderly, in left ventricular tachycardia, right ventricular overload, myocardial ischemia, hypoxaemia, renal dysfunction, liver cirrhosis, sepsis and infection. NT-proBNP is useful both in the diagnosis and prognosis of heart failure and is considered to be a gold standard biomarker in heart failure similar to BNP. A cut-off point 300 pg/ml has 99% sensitivity, 60%specificity and NPV 98%for exclusion of acute heart failure. NT proBNP has also a strong prognostic value of death in acute and chronic heart failure and also predicts short and long term mortality in patient with suspected or confirmed unstable CVD. Natriuretic peptides are also prognostic markers for the RV (Right Ventricular) Dysfunction. Their release is due to myocardial stretch from right ventricular pressure overload.Finally, there are data supporting that NT-proBNP might be useful to put a time frame on atrial fibrillation of unknown onset.
{"Chemical": []}