- Effects of hypoxia on heme oxygenase expression in human chorionic villi explants and immortalized trophoblast cells. Appleton, S.D., Marks, G.S., Nakatsu, K., Brien, J.F., Smith, G.N., Graham, C.H., Lash, G.E. Am. J. Physiol. Heart Circ. Physiol. (2003)