To delineate the normal function of purine nucleoside phosphorylase and to understand the pathogenesis of the immune dysfunction associated with deficiency of this enzyme, we studied purine metabolism in a patient deficient in purine nucleoside phosphorylase, her erythrocytes and cultured fibroblasts. She exhibited severe hypouricemia and hypouricosuria but excreted excessive amounts of purines in her urine, the major components of which were inosine and guanosine. Her urine also contained deoxyinosine, deoxyguanosine and uric acid 9-N riboside. The patient's erythrocytes but not her cultured fibroblasts contained increased concentrations of phosphoribosylpyrophosphate and inosine. The metabolic abnormalities resembled those in the erythrocytes of patients with the Lesch-Nyhan syndrome. Purine nucleoside phosphorylase is a necessary component of the major, if not the sole, pathway for the conversion of purine nucleosides and nucleotides to uric acid. The increased intracellular concentrations of inosine may, by inhibiting adenosine deaminase, be related to the immunologic dysfunction.
SummaryLaboratory and pilot-plant high-speed bead mills of 0.6 and S liter capacity and consisting of four and five impellers in series, respectively, were used to follow the batch and continuous disruption of bakers' yeast (Sac.c.liurom?c.e.t ccwr,i.sicrc~). The mills are not scaled equivalents. Throughputs ranging from I x m3/sec to 12 x mYsec to 100 x 10P m3/sec for the 5 liter mill were used for continuous disruption studies. Variables studied included the effect of impeller tip speed, temperature, and packed yeast concentration (ranging from IS to 7% by weight packed yeast). Disruption kinetics, as measured by the release of soluble protein, followed a first-order rate equation, the rate constant being a function of impeller tip speed and yeast concentration. For continuous disruption studies the bead mills behaved as a series of continuous stirred-tank reactors, each impeller forming a reactor. In the smaller mill a considerable degree of backflow between the reactors was evident. For certain mixing conditions the maximum amount of releasable protein was dependent on the impeller geometry. construction material, and also the concentration of packed yeast. The relative power efficiencies of the two mills are discussed along with possible criteria for scaling of bead mills. m3/sec for the 0.6 liter mill and from 16 x
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.