A method of continuous recording of the disappearance of radioactive materials from the circulating blood is described. By cannulation of the right femoral artery of dogs and leading the tubing past a scintillation counter into the right femoral vein a complete circuit is established in which the concentration of radioactivity may be continuously monitored. Curves showing concentration of the r...

We describe an assay for 5-aminolevulinic acid dehydratase (EC4.2.1.24) activity. Radioactive [14Cjporphobilinogen, formed by action of this enzyme on [14CJo-aminolevulinic acid, is purified by passage through an ion-exchange chromatographic column before measurement with a liquid scintillation counter. The radioactive substance in the final solution was identified as solely [14C]porphobilinoge...

Significant differences in the uptake of thymidine-(3)H, percentage of labeled cells, numbers of grains per labeled nucleus, and mitotic rate were noted in rat corneal epithelium along a 24-hr time scale. These were demonstrated by injecting subgroups of five animals every hour during a 24-hr period with thymidine-(3)H, sacrificing them 2 hr later, and analyzing the corneal epithelium by scinti...

We describe an enzymic quantification of phosphatidylglycerol in amniotic fluid. Phosphatidylglycerol is hydrolyzed in alkali and the resulting glycerol is then enzymatically phosphorylated with adenosine 5'-[gamma-32P]triphosphate to yield glycero[32P]phosphate. After removal of excess [gamma-32P]ATP by charcoal, the radioactivity of the glycerophosphate is measured in a liquid scintillation c...