1. Fatty acid synthesis de novo was measured in the perfused liver of fed mice. 2. The total rate, measured by the incorporation into fatty acid of (3)H from (3)H(2)O (1-7mumol of fatty acid/h per g of fresh liver), resembled the rate found in the liver of intact mice. 3. Perfusions with l-[U-(14)C]lactic acid and [U-(14)C]glucose showed that circulating glucose at concentrations less than about 17mm was not a major carbon source for newly synthesized fatty acid, whereas lactate (10mm) markedly stimulated fatty acid synthesis, and contributed extensive carbon to lipogenesis. 4. The identification of 50% of the carbon converted into newly synthesized fatty acid lends further credibility to the use of (3)H(2)O to measure hepatic fatty acid synthesis. 5. The total rate of fatty acid synthesis, and the contribution of glucose carbon to lipogenesis, were directly proportional to the initial hepatic glycogen concentration. 6. The proportion of total newly synthesized lipid that was released into the perfusion medium was 12-16%. 7. The major products of lipogenesis were saturated fatty acids in triglyceride and phospholipid. 8. The rate of cholesterol synthesis, also measured with (3)H(2)O, expressed as acetyl residues consumed, was about one-fourth of the basal rate of fatty acid synthesis. 9. These results are discussed in terms of the carbon sources of hepatic newly synthesized fatty acids, and the effect of glucose, glycogen and lactate in stimulating lipogenesis, independently of their role as precursors.

Aminooxyacetate is a potent inhibitor of glutamate: oxaloacetate transaminases from both rat and guinea pig kidney cortex. In guinea pig kidney cortex, phosphoenolpyruvate carboxykinase activity was found to be 59% cytoplasmic, 41% mitochondrial. Mitochondrial phosphoenolpyruvate carboxykinase activity is expressed only after sonication indicating that the enzyme is located within the inner mitochondrial membrane. Aminooxyacetate inhibits gluconeogenesis from lactate, but not from pyruvate, in both rat and guinea‐pig kidney cortex. It is concluded that gluconeogenesis in guinea‐pig kidney cortex proceeds by a pathway involving cytoplasmic, rather than mitochondrial phosphoenolpyruvate carboxykinase.

Prostatic acid phosphatase was purified from human semen and its purity established by biochemical and immunological criteria. Rabbits were injected with the purified isoenzyme to raise specific antisera. The prostatic acid phosphatase was radiolabeled with 125I by the Chloramine T method. We developed a fully automated double-antibody radiommunosassay for measuring prostatic acid phosphatase in serum from patients with carcinoma of the prostate and from several control groups. The lower detection limit of the radioimmunoassay was 2.0 microgram of prostatic acid phosphatase per litre of serum. Values for most members of the control group was <2.0 microgram/L; patients with metastatic carcinoma of the prostate had values ranging from <2.0 to 300 microgram/L of serum.