Studies on the sialic acid of platelets in adults, newborns, and cases with various kinds of diseases were carried out by the method of Madoff and Warren. Additionaly the sialyltransferase of platelets was asssyed on the platelets of adults and newborns by the Bosman's method which was partially modified by us. The sialic acid of platelets in newborns was markedly low (Fig. 1) and the sialic acid of a case with Bernard-Soulier syndrome was low in the meaning of per protein of platelet, though rather high by the case of single one platelet (Table 1). The changes of sialic acid in the MLNS (acute febrile mucocutaneous lymph node syndrome) during the course of illness were interesting. The sialic acid of platelets decreased at 10 to 20 days from the onset of the illness and then increased slowly up to the normal range in accordance with improvement (Fig. 2). By the administration of flurbiprofen, the sialic acid increased rapidly, being decreased by cessation of the administration.
The sialyltransferase of platelets in newborns and cord blood were seemed to be slightly low in our present results. In order to get final conclusion on the sialyltransferase of platelets in newborns, further studies would be necessary.