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Both had impaired lung function and abnormal computed tomographic scans, and their condition improved when nitrofurantoin was withdrawn and corticosteroid treatment commenced.
 ( potential therapeutic event: improved ,  Both had impaired lung function and abnormal computed tomographic scans: Subject, Both: Subject.Population, abnormal computed tomographic scans: Subject.Disorder, nitrofurantoin was withdrawn and corticosteroid treatment commenced: Treatment, corticosteroid: Treatment.Drug, nitrofurantoin: Treatment.Drug, impaired lung function: Treatment.Disorder) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: adverse event,potential therapeutic event, Arguments type: Treatment.Disorder,Treatment.Time_elapsed,Treatment.Dosage,Subject.Race,Treatment.Drug,Treatment.Route,Subject.Disorder,Treatment.Freq,Treatment,Effect,Subject.Population,Treatment.Duration,Combination.Drug,Subject,Subject.Age,Subject.Gender. 
Text: {0} 
Answer:
 ( potential therapeutic event: improved ,  Both had impaired lung function and abnormal computed tomographic scans: Subject, Both: Subject.Population, abnormal computed tomographic scans: Subject.Disorder, nitrofurantoin was withdrawn and corticosteroid treatment commenced: Treatment, corticosteroid: Treatment.Drug, nitrofurantoin: Treatment.Drug, impaired lung function: Treatment.Disorder) 