MPO and periodontitis: The treatment with WY14643 attenuates: (1) Myeloperoxidase activity, (2) cytokines and adhesion molecules expression, (3) NF-κB expression, (4) iNOS expression, (5) the nitration of tyrosine residues (6) activation of the nuclear enzyme poly (ADP-ribose) polymerase, (7) apoptosis (8) the degree of gingivomucosal tissues in rats subjected to ligature-induced periodontitis.