The synergistic effects of testosterone and phophodiesterase-5 inhibitor combination on oxidative stress markers, matrix metalloproteinases and oxidative DNA damage: A randomized controlled experimental study Rahmi Aslan; Kerem Taken; Akif Erbin; Hamit Hakan Alp; Recep Eryilmaz; Omer Sarilar; Zubeyir Huyut;