The Hyperplastic Reaction of the Skin to Sulphydryl and Its Significance in Neoplasia

Recognition of the significant role played by the sulphydryl group places a powerful tool in the hands of experimenters in cell proliferation, be they biologists, physiologists, pathologists, or others interested in this field. There are two fundamentals which must be appreciated, viz., first, -SH is the naturally occurring chemical group in cell division, as actually discovered in dividing cells; second, cell proliferation is regulated by an equilibrium between chemical compounds in which -SH is the key group. Chemically speaking, this equilibrium is, in many respects, unique, inasmuch as it depends on changes of valence, oxidation, reduction, and hydrolysis of extremely labile chemical groups revolving around the one element, sulphur. The directions in which this equilibrium may shift in living organisms have been charted in principle by Hammett (1). It is obvious that many circumstances alter the levels of the equilibrium in respect to the different stages of oxidation, etc., of the sulphur, and this must be rigidly controlled in experiment; knowledge of sulphur metabolism in mammals is only in its beginnings (2). Since the -SH group has been demonstrated to occur under natural conditions within the nuclei of dividing cells, it follows that offering -SH-containing compounds to proliferating cells will increase their rate of division unless their nuclei contain as much sulphur as they can use for this purpose. Abundant experimental evidence has been provided (first by Hammett) that cell division rate is increased by appropriate -SH compounds in a number of different organisms, both plant and animal, and in a number of different expressions of cell division. The later work of Voegtlin and Chalkley (3), using the -SH compound, glutathione, shows that even the lowly ameba responds. The effects of sulphydryl