The mechanism of increased α-fetoprotein (AFP) production following a single injection of ethionine was investigated by using 35 day-old rats at the time of sacrifice. After administration of DL-ethionine or L-ethionine, marked elevations of serum AFP concentrations occurred in 4 days either with male or female rats. D-Ethionine, however, did not cause the increase in serum AFP level. In adult rats, the increase in serum AFP level was less prominent in the male as compared with the female. No apparent necrosis of liver cells was observed in ethionine-treated rats. Frequent administration of ATP after the single dose of ethionine reduced the increases in liver triglyceride and serum AFP levels. The increased concentrations of serum AFP, reaching a maximum level in 4 days, occurred before a slight increase in hepatic DNA synthesis. The serum AFP from ethionine-treated rats was immunologically and electrophoretically indistinguishable from that in fetal, carbon tetrachloride (CCl₄)-injured or hepatoma-bearing rat. These observations suggest that the increased production of AFP in ethionine-treated rats is closely associated with the hepatic injury and is not the consequence of liver cell regeneration.

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By means of affinity chromatography anti-catalase antibody was isolated and purified from sera of rabbits immunized with purified rat liver catalase. The antigen was conjugated with CNBr-activated Sepharose 4B. IgG fraction of the immune sera was subjected to chromatography on a column of this immunoadsorbent. The antibody was released from the antigen at pH 2.8-3.0.
Antibody thus purified, was estimated to have a purity over than 90%. It showed an identical behavior on electrophoresis to the rest of IgG of the immune serum, and its amino acid composition was extremely similar to that of the latter. One μg of the purified antibody was found to be equivalent to 0.4μg of the antigen, suggesting that no inactivation occurred during the course of purification.
Diffusion of rat liver cell fractions in agar against the purified anti-catalase antibody gave a second weaker precipitin line in addition to the predominant one, which was common to purified catalase.
Iodination of the purified antibody yielded a preparation of I¹²⁵-antibody having a specific radioactivity of 400, 000 cpm per mg, with a slight loss in immunological activity.

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In rabbits receiving whole body irradiation with ⁶⁰Co in a single dose of 800R, a dose alleged to represent the LD₅₀ for this animal species, a study was made of the time course of consequent changes in serum proteins and immunoglobulins as estimated by electrophoresis and immunoelectrophoresis respectively.
The results obtained are as follows:
1) Serum albumin decreased in all cases, its response occurring immediately after irradiation.
2) The serum α₁-globulin level showed no definite tendency, whereas there was a rise in serum α₂-globulin level in almost all cases, with a peak attained around the 2nd day after irradiation.
3) Serum β-globulin was the fraction that responded most distinctly, beginning to increase shortly after irradiation and reaching the maximum around the 5th day.
4) The serum γ-globulin level varied in no consistent fashion, although it declined transiently immediately after irradiation in more than half the cases.
5) The present study suggests that lowered albumin and elevated α- and β-globulin levels may be characteristic of the pattern of radiation-induced variations in serum protein fractions.
6) Immunoelectrophoretically, there was noted an increase in transferrin, and no appreciable change was observed in IgG, IgM or IgA.

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