- Plasma pituitary hormone responses to the synthetic enkephalin analog (FK 33-824) in normal subjects and patients with pituitary diseases. Demura, R., Suda, T., Wakabayashi, I., Yoshimura, M., Jibiki, K., Odagiri, E., Demura, H., Shizume, K. J. Clin. Endocrinol. Metab. (1981)