Hematologic malignancy has rarely been reported in adults with sickle cell disease. We describe four sickle cell patients (two with hemoglobin SC, two with hemoglobin SS) who developed hematologic malignancy (acute myeloblastic leukemia, multiple myeloma, malignant histiocytosis, and Hodgkin's disease). Three of the cases represent the first adult association between SC or SS hemoglobinopathy and the particular malignancy involved. Sickle hemoglobin does not appear to exert a protective effect against childhood hematologic malignancies, suggesting that better survival in sickle cell disease may be accompanied by an increased incidence of hematologic neoplasms in adulthood. Karyotypic analysis revealed alterations of chromosome 5 in two sickle cell patients with leukemia, raising the possibility of a chromosomal link between the two diseases. Further epidemiologic and cytogenetic studies are needed to define the relationship between hematologic malignancy and sickle cell disease.

A B S T R A C TrThe effects of thyroid hormn-one on guinea pig imiyocardial NaK-ATPase activity, transmemnbranie imion-ovalenit cationi active transport, and cardliae glycosi(le binlding were examined. NaKATPase activities of left atrial anid left ventricular homiogeniates of control and triiodothyronine (T3)-treated animiials were determinecl, and compared to activities of skeletal mluisele and( liver. T3 administrationi was associated withl a significanit increase of 18% in left atrial and left ventricular NaK-ATPase specific activities. This increment was less than that notedI in skeletal mltusele (+42%) and liver (+30%). To (letermiinle if enhanicedl NaK-ATPase activity was accomiipanied by increased monovalent cation active tranisport, in vitro 86Rb+ uptake by left atrial strips and hemiidliaplhragmiis was measured. Transition from the euthyroid to the hyperthyroid state resulted in a 68% increase in active 86Rb+tuptake by left atrium, and a 62% increase in active uiptake by (liaphragm. Passive 86Rb+ uiptake was nlot affected in either tissue.Ouabain binding by atrial and ventricular homogeniates of T3-treated animials was increased by 19 and 17%, respectively, comppared to controls, in close agreemiient with thyroid-induced increments in NaKATPase activity. Taken together, these results are consistenit with enhanced myocardial NaK-ATPase activity and imonovalent cation active transport due to an increase in the number of finctional enzyme complexes.

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