(S (S (PP (IN Since) (NP (BASENP (NN completion)) (PP (IN of) (BASENP (DT the) (NN surgery))))) (COMMA ,) (S (BASENP (DT the) (NN patient)) (VP (VBZ has) (VP (VP (VBN been) (PP (IN on) (BASENP (JJ immuno-suppressant) (NNS drugs)))) (S (VP (TO to) (VP (VB prevent) (NP (BASENP (NN rejection)) (PP (IN of) (BASENP (DT the) (JJ new) (NNS limbs))))))))))) (PERIOD .))