Tryptophan regulates the chorionic vascular tone and chorionic endothelial indoleamine 2, 3-dioxygenase-1 is deficient in intrauterine growth restriction and preeclampsia. (September 2015) - Zardoya Laguardia, P.; Blaschitz, A.; Lang, I.; Gauster, M.; Frank, S.; Wadsack, C.; Haeusler, M.; Cervar-Zivkovic, M.; Sedlmayr, P.