Complex sentence: As an adolescent Brenner engaged as a cofounder of the Deutsche Gesellschaft für Kosmologie (DGK), was editor and co-publisher of the "Zeitschrift für Kosmologie" 1990-2007.
Split into simpler sentences: As an adolescent Brenner was engaged as a cofounder of the Deutsche Gesellschaft für Kosmologie (DGK). He was editor and co-publisher of the "Zeitschrift für Kosmologie" 1990-2007.