alkaline phosphatase ( ap ) activity was assayed by a sensitive fluorometric method , using 4-methylumbelliferyl phosphate as substrate , in homogenates of confluent skin fibroblasts from 17 patients with the infantile , childhood , or adult form of hypophosphatasia and compared to the ap activity in 22 sex- and age-matched control cell lines .
C0231330
infantile
C0231335
childhood