Biomedical subjects

Takeshi Mitsuyasu

Publications and source records attributed to Takeshi Mitsuyasu.

3 recordsLinked to original sources

PubMed2002

Epithelial stem cells in teeth.

Many tissues and organs maintain a process known as homeostasis, in which cells are replenished as they die as a result of apoptosis or injury. The continuously growing mouse incisors are an excellent model for studying the molecular mechanisms of cell homeostasis, renewal, and repair. We elucidated these mechanisms in mouse incisors by detecting adult stem cells and analyzing the stem cell lineage by bromodeoxyuridine (BrdU) labeling analysis. The stem cells divide slowly, giving rise to a daughter cell that remains in the cervical loop and a second daughter cell that enters the zone of rapidly dividing inner enamel epithelial cells (transit-amplifying cell population). During subsequent rounds of cell division, the latter cells move toward the incisal end and differentiate into ameloblasts that form the enamel matrix. Recent evidence from gene knockout mice suggests that fibroblast growth factor (Fgf10) plays an important role in the formation and maintenance of stem cells in the development of mouse incisors. The role of dental stem cells in odontogenic tumors is discussed.

Journal Article↗

PubMed2002

Comparison of long-term results between different approaches to ameloblastoma.

OBJECTIVE: The long-term results of different surgical approaches to ameloblastoma were compared to develop a more rational surgical approach to this tumor. STUDY DESIGN: Seventy-eight primary ameloblastomas, including 27 unicystic, 21 multicystic, and 30 solid-type tumors, were examined in this study. The methods of treatment consisted of radical surgery (ie, resection-both segmental and marginal) and conservative treatments (ie, marsupialization alone, marsupialization followed by enucleation with sufficient bone curettage if necessary, and enucleation with bone curettage). The effect of marsupialization on recurrence data after a follow-up period of at least 5 years was evaluated with respect to clinical type and histologic pattern. RESULTS: Marsupialization was performed in 31 cystic ameloblastomas before surgery, and the effective rate of marsupialization was 74.2%. Recurrence was observed in 7.1% (3/42) after radical surgery and in 33.3% (12/36) in conservative treatments. Relatively higher tendencies of recurrence were observed in the multicystic type and follicular and/or plexiform pattern tumors. CONCLUSIONS: Conservative treatments including marsupialization and enucleation followed by sufficient bone curettage were thought to be useful, reducing the need for jaw resection. This result extends the indications for conservative treatment of ameloblastoma.

Adolescent↗

PubMed2002

Marsupialization for odontogenic keratocysts: long-term follow-up analysis of the effects and changes in growth characteristics.

OBJECTIVE: This study evaluated the effects of marsupialization on odontogenic keratocysts (OKCs) and its role in conjunction with enucleation and curettage. STUDY DESIGN: Twenty-eight primary OKCs, treated by marsupialization before enucleation and curettage, were examined in this study. The effect of marsupialization and recurrence data after a follow-up period of at least 3 years were evaluated. The changes of growth characteristics during marsupialization were analyzed by means of histopathologic and immunohistochemical studies with monoclonal anti-Ki-67 antibody. RESULTS: The effect of marsupialization was evaluated as extremely effective (64.3%), moderately effective (32.1%), and poorly effective (3.6%). In 5 lesions, the cysts disappeared macroscopically and further surgery was not done. Recurrence was observed in 6 lesions (21.4%), and there was no significant difference in recurrence rates between the lesions treated with or without marsupialization. There appeared to be a predilection for recurrence in the lesions in the mandibular ramus region and also for radiographically multilocular lesions. Microscopic examination showed substantial changes from a parakeratinized or orthokeratinized epithelium into a hyperplastic, stratified, nonkeratinizing squamous epithelium after marsupialization in many cases. There was no significant difference in labeling index between premarsupialization (20.2% +/- 12.0%) and postmarsupialization (15.3% +/- 10.3%). CONCLUSION: Marsupialization was found to be effective as a preliminary treatment for large OKCs. This procedure does not appear to affect the recurrence tendency of OKCs, and the probable changes in growth characteristics become rather less aggressive.

Adolescent↗