Bone tracer uptake in a ureteric calculus.

Technetium-99m methylene diphosphonate was observed to concentrate in a mildly obstructive left ureteric calculus. The bone scan findings alerted the clinicians to this possibility, which was subsequently confirmed and the patient successfully treated. The stone was heterogeneous in texture and predominantly formed from magnesium ammonium phosphate. At extraction the major fragment contained 0.4% of the injected bone tracer dose and autoradiography demonstrated peripheral tracer distribution within the calculus.

On the possible significance of the transamidination reaction in evolution.

The origin of the various muscle phosphagens during evolution is considered in the context of the need to conserve ornithine for the synthesis of proline for connective tissue necessary for structural strength and flexibility and/or a complicated musculature. In each phosphagen, arginine is known to have contributed its amidine moiety thus maintaining the function of the phosphagen and setting free the proline precursor ornithine. Tissues from an earthworm, a starfish and a sea-squirt have been found to contain the enzymes arginase, ornithine aminotransferase and pyrroline-5-carboxylate reductase which are necessary to convert arginine to proline. For each of the animals studied analysis for the relevant free amino acids and for the characteristic amino acids (Pro, Oh-Pro, Oh-Lys, Gly) of collagen are presented. The amino acid composition of the diet of the sea-squirt Pyura stolonifera and of the starfish Coscinasterias calamaria is presented along with the level of the phosphagen kinases of the animals studied. The significance of the experimental results is discussed in connection with the importance of the transamidination reaction.