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:

A randomized , double-blind , placebo-controlled MRI study of anti-herpes virus therapy in MS . OBJECTIVE To evaluate the effect of treatment with the antiherpes drug valacyclovir on MRI-evident lesions in patients with relapsing-remitting MS in a phase 2 , randomized , double-blind , placebo-controlled study . BACKGROUND It has been postulated from virologic studies that herpesvirus infection could play a role in the progression of MS. METHODS Patients were eligible for the study if they had had two or more MS relapses in the 2-year period before enrollment . Seventy patients with Expanded Disability Status Scale scores of 0 to 5.5 were randomly assigned to receive 1 gram of valacyclovir ( n = 36 ) or placebo ( n = 34 ) three times daily for 24 weeks . Patients underwent MRI every fourth week for 32 weeks : twice during pretreatment , six times during treatment , and once after treatment . Scoring of neurologic disability was performed at the start and end of the treatment period . The primary endpoint was the number of new active MRI-evident lesions over 24 weeks of treatment . Secondary endpoints included other MRI measures and clinical endpoints . RESULTS The mean number of new active lesions +/- SD per patient during 24 weeks of treatment with valacyclovir was 11.9 +/- 17.6 and that during placebo treatment was 14.5 +/- 21.4 . A protocol-planned exploratory analysis stratified patients according to baseline activity ; this analysis showed that patients with high levels of disease activity in the valacyclovir treatment group ( n = 17 ) developed fewer new active lesions per scan than did those in the placebo treatment group ( n = 11 ) . The median number ( Q ( 1 ) , Q ( 3 ) range ) of active lesions was 2.0 ( 1.38 , 3.96 ) in the valacyclovir treatment group and 6.5 ( 2.63 , 9.0 ) in the placebo treatment group . CONCLUSIONS Valacyclovir treatment did not reduce the formation of active lesions in patients with relapsing-remitting MS who had two or more relapses during the previous 2-year period . In a subgroup of patients with high levels of disease activity who had more than one active MRI-evident lesion during 4 weeks , valacyclovir treatment was associated with a reduced number of new active MRI-evident lesions and with an increase in the number of scans free of new active lesions . The results of the exploratory subgroup analysis provide support for further studies of antiherpes therapy for patients with MS and high levels of MRI-evident disease activity .
{"Intervention": ["anti-herpes virus therapy", "Valacyclovir", "placebo", "valacyclovir", "antiherpes therapy", "placebo-controlled", "antiherpes drug valacyclovir"], "Outcome": ["clinical endpoints", "MRI-evident lesions", "Scoring of neurologic disability", "active lesions", "new active lesions", "other MRI measures", "new active MRI-evident lesions", "number of new active MRI-evident lesions"], "Participant": ["MS", "MRI-evident disease activity", "anti-herpes", "Seventy"]}