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: ["Outcome", "Participant", "Intervention"].

Please return the output as a JSON object of the format: {"Participant" : ["patients with COPD", ...], "Intervention" : ["Atenolol", ...], "Outcome" : ["blood pressure", ...]}. 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:

The UKEP study : multicentre clinical trial on two local regimens of urokinase in massive pulmonary embolism . The UKEP Study Research Group . A multicentre trial ( 10 centres ) of urokinase ( UK ) was performed in patients with acute severe pulmonary embolism ( PE ) . The aim of this trial was , to compare the efficacy of two doses of UK administered via a catheter in the pulmonary artery : 2000 IU kg-1 h-1 for 24 hours ( UK 2000 ) in conjunction with heparin versus 4400 IU kg-1 h-1 UK alone for 12 hours ( UK 4400 ) followed by heparin . PE was less than 5 days old and the clinical diagnosis was confirmed by pulmonary angiograms demonstrating a vascular obstruction of more than 30 % ( Miller 's index greater than 11 ) . The efficacy of treatment was evaluated by the degree of early revascularization ( pulmonary angiograms were performed 30 to 48 hours after initiation of thrombolytic treatment and analysed blindly by four independent vascular radiologists ) . 133 patients were included in this trial : two patients died before treatment and two were excluded retrospectively , leaving 129 patients for final analysis ( 67 : UK 2000 + heparin ; 62 : UK 4400 ) . The two groups had similar pretreatment clinical , haemodynamic and angiographic characteristics : the Miller angiographic index of severity averaged 22.6 +/- 3.7 for patients in the UK 2000 group , and 22.6 +/- 3.4 for patients in the UK 4400 group ( average filling defect of 66 % on pulmonary angiograms ) . There was a similar and significant degree of resolution in the two groups : 26 % and 20 % , respectively . Minor and major bleeding problems were observed with equal frequency in the two groups ( 24 % and 29 % , respectively ) . These bleeding complications were severe in only 4.5 % and 3 % , respectively . ( ABSTRACT TRUNCATED AT 250 WORDS )
{"Intervention": ["two doses of UK", "thrombolytic treatment", "a catheter in the pulmonary artery : 2000 IU kg-1 h-1 for 24 hours ( UK 2000 ) in conjunction with heparin versus 4400 IU kg-1 h-1 UK alone for 12 hours ( UK 4400 ) followed by heparin", "A multicentre trial ( 10 centres ) of urokinase ( UK )", "urokinase"], "Outcome": ["significant degree of resolution", "died", "Miller angiographic index", "Minor and major bleeding problems", "degree of early revascularization"], "Participant": ["patients with acute severe pulmonary embolism ( PE ) ."]}