We describe a simple, efficient, procedure for labeling oligonucleotides to high specific activity (< 1 x 10(8) cpm/mumol) by hydrogen exchange with tritiated water at the C8 positions of purines in the presence of beta-mercaptoethanol, an effective radical scavenger. Approximately 90% of the starting material is recovered as intact, labeled oligonucleotide. The radiolabeled compounds are stabl...

Water space, tritiated water flux, drinking and urine flow rates of the brown trout were decreased by increasing the environmental calcium concentration. Diffusional and osmotic permeabilities were identical in fresh water. This suggests that water flow across the gill occurs entirely by diffusion. Previous suggestions of a discrepancy between the two permeabilities in freshwater teleosts could...

The determination of the rate of cholesterogenesis has usually involved either the measurement of the incorporation of a radiolabelled substrate, such as acetate, or the assay of the enzyme /I-hydroxy-p-methylglutaryl-CoA reductase (EC 1.1.1.34), commonly believed to be rate-limiting. However, the use of acetate is of doubtful physiological relevance, and the size and rate of turnover of the fr...

Total body water and total body potassium were studied in 14 patients submitted to proctocolectomy six to 10 years after they had been provided with a continent ileostomy. Total body water was determined with an isotope dilution technique using tritiated water as a tracer. Total body potassium was determined by counting the gamma radiation from the naturally present nuclid 40K in a total body c...