Retrospective study of ameloblastoma: the possibility of conservative treatment.

At our institutions, most cases of the solid or multicystic type were treated as conservatively as possible in order to avoid disadvantages of radical treatment. The aim of present study was to retrospectively analyze the ameloblastoma cases diagnosed at our two institutions, to classify them according to the criteria of the 2005 WHO classification, and to evaluate the possibility of using a conservative approach for the surgical treatment of ameloblastoma. Maxillary cases, unicystic cases, peripheral cases and resection-treated cases were excluded from this study. In 23 tumors of mandibular solid or multicystic ameloblastoma, a patient's age, gender, location, clinical signs, duration, radiographic appearance, preoperative diagnosis, ameloblastoma subtypes, treatment, and recurrence were investigated. The recurrence rate (48.7%) in this study was lower than the reported recurrence rate after conservative treatment for solid or multicystic ameloblastoma and was higher than the reported recurrence rate of ameloblastoma, inclusive of other types. However, all patients who were diagnosed with recurrences have maintained their quality of life and were satisfied for at least several years after the conservative treatment. In conclusion, we demonstrated one possibility that a conservative approach might be employed in the surgical treatment of ameloblastoma (even of the solid or multicystic type).

Defect of human immunodeficiency virus type 2 Gag assembly in Saccharomyces cerevisiae.

We have previously shown that the expression of human immunodeficiency virus type 1 (HIV-1) Gag protein in Saccharomyces cerevisiae spheroplasts produces Gag virus-like particles (VLPs) at the plasma membrane, indicating that yeast has all the host factors necessary for HIV-1 Gag assembly. Here we expand the study by using diverse primate lentiviral Gags and show that yeast does not support the production of HIV-2 or simian immunodeficiency virus SIVmac Gag VLPs but allows the production of SIVagm and SIVmnd Gag VLPs. Particle budding was observed at the surfaces of cells expressing SIVagm and SIVmnd Gags, but cells expressing HIV-2 and SIVmac Gags showed only membrane-ruffling structures, although they were accompanied with electron-dense submembrane layers, suggesting arrest at an early stage of particle budding. Comparison of HIV-1 and HIV-2 Gag expression revealed broadly equivalent levels of intracellular Gag expression and Gag N-terminal myristoylation in yeast. Both Gags showed the same membrane-binding ability and were incorporated into lipid raft fractions at a physiological concentration of salt. HIV-2 Gag, however, failed to form a high-order multimer and easily dissociated from the membrane, phenomena which were not observed in higher eukaryotic cells. A series of chimeric Gags between HIV-1 and HIV-2 and Gag mutants with amino acid substitutions revealed that a defined region in helix 2 of HIV-2 MA (located on the membrane-binding surface of MA) affects higher-order Gag assembly and particle production in yeast. Together, these data suggest that yeast may lack a host factor(s) for HIV-2 and SIVmac Gag assembly.