Extraskeletal osteosarcoma with pulmonary metastasis in a female f344 rat.

A subcutaneous mass in the right femoral region of a female F344 Slc/N rat was examined histopathologically. At 83 weeks of age, the animal showed symptoms of severe anemia and nasal bleeding. Necropsy revealed that the mass had invaded the skeletal muscles but did not affect the bones. Multicentric nodules were also observed in the lung. Histopathology revealed a sheet-like growth pattern of polygonal tumor cells with round or comma-shaped nuclei and pale eosinophilic cytoplasm. Osteoid tissue was observed in not only the original lesion but also the metastatic foci in the lung. Each tumor cell was surrounded by argentophil fibers and few collagen fibers. Immunohistochemically, the tumor cells were positive for proliferating cell nuclear antigen (PCNA), vimentin, osterix and osteocalcin, but negative for keratin, S-100, von Willebrand factor, CD-31, CD-34, desmin, α-smooth muscle actin, lysozyme, α1-antitrypsin and rat malignant fibrous histiocytoma (MFH) antigen. CD-68-positive cells were considered to be infiltrated macrophages because they were negative for PCNA. On the basis of these findings, we diagnosed the present case as extraskeletal osteosarcoma.

Efficient delivery of antibody into living cells using a novel HVJ envelope vector system.

Introduction of antibodies which retain their function into cells using a simple and easy method would be very useful for study of the intracellular events in living cells. In this study, we developed a new method for intracellular delivery of antibody. It includes a combination of a novel IgG-capturing protein and hemagglutinating virus of Japan envelope (HVJ-E), an inactivated Sendai virus particle which can deliver a variety of molecules into mammalian cells via membrane-fusing activity. The IgG-capturing protein, which was molecularly designed to have two functions, was prepared as a fusion protein (ZZ-NP) of ZZ-dimer derived from an immunoglobulin-binding domain of protein A and nucleocapsid protein (NP), a part of the structural protein of HVJ. ZZ-NP was efficiently incorporated into the HVJ-E particle by treatment with detergent, and enhanced the incorporation of IgG. Moreover, fluorescence immunostaining revealed that the incorporated antibody was very efficiently introduced into living cells while retaining its function, i.e. anti-NPC (nuclear pore complex) monoclonal antibody was selectively located around cell nuclei. These findings suggest that this method is useful for intracellular delivery of antibody and for analysis of biological function of sub-cellular molecules in living cells.