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On the basis of a study of the action of phosphoribosylpyrophosphate (PRPP) synthetase (EC 2.7.6.1.) in 22 hyperuricemic and 9 normal subjects, the authors report two cases of gout with anomalies of the kinetics of this enzyme. The anomaly consists of an increase in affinity for inorganic phosphate (iP) in the absence of inhibitors, and a decrease in inhibition by low concentrations of ADP in the presence of iP. These patients show no other anomaly of intraerythrocyte PRPP (dosage and production "in vitro"), hypoxanthine-guanine-phosphoribosyl-transferase and APRTase (overall activity and apparent Km). These two cases of gout are characterized clinically by their early occurrence, appearing in one case in a pre-menopausal woman, their family character and their normal sensitivity to allopurinol.

This paper describes a morphologic, quantitative, cytochemical study of mononuclear non lymphoid cells in knee synovial fluid in osteoarthritis and various arthritides. Morphologic criteria allow to identify among these cells various synoviocytic and monocytic subtypes with in both types, phagocytic subtypes. Quantitative study shows in arthritides an important afflux of monocytes and a hyperexfoliation of synoviocytes. In fluids with intermediate cellularity, Monocytes/Synoviocytes ratio allows the differential cytodiagnosis between osteoarthrosis and arthritis. All monocytic subtypes and especially the phagocytic one are highly significantly increased in arthritides. Synoviocytic subtypes show a lower increase, except the phagocytic one, which is not changed. Giant multinuclear synoviocytes are found in every type of disease and cannot constitute a cytodiagnosis marker. Alcian Blue and hyaluronidase treatment show hyaluronate in a few percentage of Synoviocytes. Cytoenzymologic study shows that synoviocytes and monocytes are positive in all tested hydrolases: beta Glucuronidase, Acid Phosphatase, alpha Naphthyl Acetate Esterase, these activities being always higher in synoviocytes. With peroxidase, synoviocytes are always negative, so this reaction although it marks only a minority of monocytic population can be used as an extra cytologic criterion for discrimination of mononuclear cells in synovial fluid. In these four enzymes there is no significant quantitative difference at cellular level between osteoarthrosis and arthritides. Lysosomal enzymatic activity in both monocytic and synoviocytic cells confirms their heterophagic properties. However synoviocytic heterophagy seems to be a physiological process not or few affected by inflammatory events. On the opposite, monocytic heterophagy and then macrophagic transformation of monocytes appears as a major aspect of intrasynovial inflammatory reaction. If a large majority of exfoliated synoviocytes comes from A type synovial lining cells and if they belong to Mononuclear Phagocyte System, why do they so weakly, or not, participate as phagocytes to inflammatory reaction.