The aim of lathyrogen therapy is, in short, to bring about the disappearance of the cross linkings of the collagen fibers and elastin in the sc1 erotic foci, thus increasing the amount of the soluble component. In the past three years, the author treated 10 cases of progressive systemic sclerosis (PSS) with N-aminoacetonitrile (PCPG-AAN), a newly developed lathyrogen, and obtained satisfactory therapeutic results in the majority of the cases. It seems that PCPG-AAN produces less side effects compared with the other lathyrogens and is effective against not only sclcroden,1a in PSS, but also against the visceral lesions. In addition, it was confirmed that PCPG-AAN can suppress the proliferation of the chick embryo fibroblasts on culture as well as of the mature collagen fibers
