Depression of liver catalase by various agents.

I t is now a well established fact tha t liver catalase activity is diminished in tumor-bearing hosts which carry any one of a variety of types of cancer. Since the tumor may be located at a distance from the liver, the effect is systemic (2, 3, 9, 13, 19, 20, 24). Nakahara and Fukuoka (26, 27) have reported tha t the agent responsible for the depression of liver catalase is found abundantly in cancerous tissues and not in normal tissues in a significant amount. This agent is designated toxohormone, and it contains specific amino acids (17). The injection of tumor fractions into normal mice is followed by a diminution in liver catalase activity (18), and crystalline catalase activity in vitro is depressed when a tumor Koehsafl is incubated with the enzyme (21). In vitro depressions of crystalline catalase activity have been observed following incubation with boiled extracts from normal tissues (14) and ovomucoid (1). That tumor tissues are not the only tissues capable of depressing catalase activity in vivo was reported by Day et al. (12). Homogenates of lyophilized spleen taken from noncancerous mice were shown to cause a lowering of liver catalase activity when injected into normal mice. Also, it has been reported tha t autolyzed liver homogenates contain a factor which depresses liver catalase activity (29). Other investigators have not assigned a significant role to normal tissue factors regarding their capability to alter catalase activity of the liver (2, 18, 24, 27). However, other agents have been found to exert an effect on this liver enzyme. Some of these agents include dietary alterations (6, 9, 11, 28), leprosy bacteria (18), chemical agents (7, 22, 29), and hormonal influences (4, 5, 10, 11).