[Successful completion of left total hip arthroplasty by inhibitor neutralization therapy in a hemophilia B patient with high responding inhibitor].

Major surgery in hemophilia patients has been facilitated by the development of coagulation concentrates. However, it is still difficult to manage bleeding during major surgery in patients with inhibitors to FVIII/IX. In addition, there have been few reports of major surgery in hemophilia B with high responding inhibitors. We report a 26-year-old hemophilia B patient with high responding factor IX inhibitor who demonstrated severe hemophiliac arthropathy in his left hip joint. Total hip arthroplasty was performed with a high dose of FIX followed by recombinant FVIIa. His inhibitor titer was decreased from 111 BU/ml to 1.0 BU/ml at surgery by avoiding the use of FIX concentrates. Thus, we could use high dose FIX for the management of surgical bleeding. Anamnestic response occurred on the 7th day after surgery and FIX concentrates were switched to recombinant FVIIa. The whole process was safely managed without any excess bleeding or adverse effects. The successful use of high dose FIX followed by recombinant FVIIa suggests that even major surgery could be safely performed in hemophilia B patients with a low titer of high responding inhibitors.

Analysis of organ selectivity in the metastatic behavior of Dunn osteosarcoma.

In the current study, the authors established a novel metastatic model to analyze organ selective metastasis by osteosarcoma, using a murine cell line, Dunn osteosarcoma. The lung, liver, kidney, and spleen were resected from syngeneic donor mice, and a tissue fragment of the respective organs was transplanted subcutaneously into a recipient mouse. Two weeks later, tumor cells were injected intravenously and the formation of metastatic deposits in the ectopic transplants was examined. Ectopic lung transplants had a significantly higher incidence of metastasis than either liver or kidney transplants. When enzymatically dispersed organ cells that were embedded in agar gel were transplanted, intravenous injection of tumor cells also resulted in a higher metastatic rate in lung transplants than in either liver or kidney transplants. Photomicrographs and microangiographs of the transplants showed equivalent revascularization of the different organs. Radiolabeled tumor cells were deposited in equivalent amounts in the ectopic transplants of the different organs after intravenous injection. In addition, in vitro growth of tumor cells was stimulated by medium conditioned with lung tissue in a dose-dependent manner. These results suggest that organ selective metastasis by osteosarcoma is not defined anatomically or hemodynamically, but may be caused by tumor cells responding to possible paracrine factors emanating from the lung.