The influence exerted by bivalent sulfur upon oxidation processes in which fatty acids participate, served as a guide for further research. Seeking agents that would act at a still lower level of the organization, even below the cells, we considered other substances which also affect oxidation processes. Theoretically, at least, it appeared possible to induce changes at a compartment below the metazoic, at which sulfhydryl containing compounds act.

We have discussed previously the systematization of the biological activity of elements, their fundamental anti A and anti D influence, their distribution among the various levels of the organism, all related to their atomic structure and their place in the periodic chart.

All of this led us to investigate selenium which is the nonmetal element next to sulfur in the sixth series of Mendeleeff's periodic table—the series with an anti A character in which oxygen is the first member. According to its period, selenium belongs to the cellular compartment.

The first problem was the nature of the compound in which it would be active. We were particularly interested in using bivalent negative selenium because of the activity of bivalent negative sulfur. However, we did investigate the selenic and selenious acids. These acids or their sodium salts have limited effect upon viruses and microbes. An interesting effect is seen in Tetrahymena pyriformis, where a manifest cellular vacuolization is induced. The influence upon tumors, pain, organic and systemic levels is less manifest and toxic effects are great. Therefore, we prepared lipoid compounds with a predominant nonpolar group and with a negative bivalent selenium. We utilized, on a larger scale, hexyl and heptyl diselenides synthesized in our laboratories by M. Bier.

Hexyl And Heptyl Diselenides

Studies have shown that hexyl and heptyl diselenides are lower in acute and chronic toxicity than selenic and selenious acids and their sodium salts. In wounds and tumors, these selenium preparations induce a relatively limited fixation of chlorides, the increase above controls being only about 16%. In only a very few cases could any direct effect upon pain be observed within a few hours. However, the long range effects after several days of administration, seemed to be superior to those of various fatty acid preparations. This was true both for the decrease in intensity of pain with an acid pattern and the increase of pain with an alkaline pattern. The effects persisted for many days. In animal tumor experiments, there were relatively slight changes in growth or survival time.

No manifest influence was seen at the organic level. With relatively large amounts of these agents, an involution of the lymphatic system was obtained. Thymus, lymph glands and spleen were markedly reduced in size in animals dying after acute toxicity tests, and adrenals were small and appeared to be depleted of their sudanophilic content. In rats, a frank lymphopenia followed administration of larges doses of these preparations, and eosinophilopenia also was uniformly seen. Changes in urine analyses also were obtained with high doses.

It is noteworthy that administration of diselenide to a subject with a type A pattern induces the appearance of oxidizing substances in the urine, as one of the first changes.

Effects at the cellular level are seen even with microgram dosages. Vacuolization occurs in the cellular cytoplasm. It is interesting to note that, despite the cellular vacuolization, pericellular edema occurs. The fact that these selenium compounds are active in small doses may be an indication that they act entirely at the cellular and not the metazoic level. This effect at the cellular level is confirmed by the fact that almost constantly the ad ministration of selenium if in sufficient amount is followed by a manifest increase in serum potassium values, and a decrease in the amount in red cells. This change in serum potassium is apparent before any other change, and is generally obtained with relatively very low doses of selenium.

The effects upon cells of another lipoidic selenium preparation, with selenium this time as the polar group, warrant mention. The preparation, synthesized in our laboratory, is hexylselenoic acid in which the hydroxyl of the carboxyl group has been replaced by a SeH radical. A manifest effect is produced by this agent in animals with ascites tumors. Intraperitoneal injection leads almost constantly to the disappearance of such tumors, even if the compound is used after ascites is already present. We used this product to bind selenium in vitro to cancerous cells as will be seen below.