TASK DEFINITION: In medical studies, treatments are tested within a group of study participants. You will be given a sentence of a study report in which your task is to list the phrases that give information about the participants of the study. You should list the phrases in the same order that they appear in the text, separated by commas. If no information about the participants is mentioned, just output "not found". Relevant information about participants include: gender, medical conditions, location, number of people participating. Do not contain participant mentions without relevant information.
PROBLEM: No clinically serious adverse events were observed in any of the groups .

SOLUTION: not found

PROBLEM: [ The effect of ionic and nonionic x-ray contrast media on myocardial perfusion and myocardial function ] .

SOLUTION: not found

PROBLEM: A comparison of different antipyretics in children with malaria showed a small effect of naproxen , but not of metamizol , on the reduction of fever peaks .

SOLUTION:
children with malaria