[Uric acid clearance in normal and gouty subjects].

substrates and products have no effect. Fractionation of normal erythrocytes by hypotonic lysis reveals a decline in the specific activity of A-PRT as the red cells age. In patients with the Lesch-Nyhan syndrome, the decline in A-PRT activity with ageing of cells is much less marked. Furthermore, the concentrations of free PRPP are as much as 10-fold elevated in the erythrocytes of these children and of patients with partial H-PRT deficiency. A good correlation exists between intracellular PRPP levels and A-PRT activity. We therefore propose that the absence or deficiency of H-PRT from the erythrocyte produces an accumulation of substrate PRPP which stabilizes the A-PRT enzyme against the loss of activity which occurs during ageing of normal erythrocytes. Discussion DR. M. K. JASANI (Horsham) Is the role of PRPP in the heat-stabilization of H-PRT or A-PRT that of a substrate as you have surmised, or is it that of a co-factor ? The data presented today could well support its role as a co-factor, adenine and hypoxanthine being the respective substrates. DR. BOYLE We know that PRPP is a substrate, as it is consumed during the reaction. We have gone into the kinetics at some length and all the kinetic data that we, and others have, support the concept that PRPP is a substrate. PROF. C. A. KEELE (London) Is there any evidence that these enzymes that are found in the lymph cells are also found in other types of body cells? DR. BOYLE Yes, there is. We studied a foetus diagnosed in utero as having the Lesch-Nyhan syndrome, the mother having elected to have a termination of pregnancy. We found that the enzyme was not detectable in the twenty different tissues that we assayed, whereas in foetuses aborted for other reasons activity could be easily detected. Moreover, the elevation of adenine phosphoribosyl-transferase enzyme was noted in all the tissues of the Lesch-Nyhan foetus. PRPP levels are known to be increased in fibroblasts of children with the syndrome. Thus we have evidence that both enzymes exhibit the reciprocal relationship in many body tissues and that PRPP levels are elevated in the two tissues (blood and fibroblasts) in which they have been measured. of Birmingham). In a group of twenty patients with ulcerative colitis, it was observed that synovial effusions occurred 2 to 5 days after starting injections of ACTH in doses of 30 to 60 i.u. daily. The first abnormal …