His incisive mind, detailed understanding of bile acid biochemistry and cholestasis, coupled with his infectious energy, resulted in these visits producing many fruitful collaborations. In parallel, he led a team of outstanding researchers first at the Karolinska Institute, and later at the Wallenberg Laboratory, Department of Medicine, Sahlgrenska Academy, University of Gothenburg. Hanns-Ulrich was mentor to many clinical and non-clinical scientists, consistently replying to requests for advice and his scientific opinion about research conundrums and complex clinical cases.