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:

Efficacy of a barrier cream and its vehicle as protective measures against occupational irritant contact dermatitis . The actual advantage of barrier creams over bland emollients for skin protection is still hotly debated . In a randomized , double-blinded study , a newly-introduced barrier cream and its moisturizing vehicle were compared regarding their skin compatibility , efficacy and resulting acceptance . Thus , 2 panels of 25 hospital nurses with mild signs of skin irritation were asked to use 1 of the test products provided ( verum or vehicle ) over a period of 4 weeks . Effects of both types of preparations were studied weekly by clinical examination and the instrumental assessment of bioengineering parameters . Results showed no significant differences between barrier cream and vehicle . In both groups , clinical skin status improved and stratum corneum hydration increased significantly during the study period . Both preparations were tolerated and accepted well , thus showing both skin protection and skin care . These results contribute to the debate as to whether a strict distinction between " skin care " and " skin protection " products is justified . The vehicle alone is capable of positively influencing skin status . Emphasis must be laid on regular , frequent , and correct application of a product for it to be effective .
{"Intervention": ["barrier cream", "verum or vehicle ) over a period of 4 weeks", "vehicle", "barrier creams", "its vehicle"], "Outcome": ["stratum corneum hydration", "occupational irritant contact dermatitis", "tolerated", "skin compatibility , efficacy and resulting acceptance", "Efficacy", "skin protection and skin care .", "clinical skin status", "and accepted well"], "Participant": ["occupational irritant contact dermatitis", "25 hospital", "skin irritation", "2 panels"]}