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Biomedical subjects

Takayoshi Sakai

Publications and source records attributed to Takayoshi Sakai.

8 recordsLinked to original sources
PubMed2006

A new attachment for proximal segment positioning for bimaxillary dysgnathic surgery--technical note.

BACKGROUND: The frequent insertion of self-tapping screws for securing the proximal positioning plate in bimaxillary osteotomy often cause loosening of screws and plate, which produces incorrect repositioning. In this article, a newly developed base-attachment for a T-shaped proximal positioning plate for bimaxillary osteotomy is presented. MATERIAL: The base-attachment set consists of a titanium base-attachment and two titanium tapped screws. The attachment has a shallow depression having the same shape as the basal part of the positioning plate. METHOD: The base-attachment is secured by self-tapping screws until the end of the procedure, and the T-shaped proximal positioning plate is placed and secured by two titanium-tapped screws. RESULT: By using this base-attachment, the T-shaped plate can be easily placed repeatedly without difficulty. CONCLUSION: This base-attachment set may be useful for the frequently repositioned proximal plate in bimaxillary osteotomy.

Bone Plates↗
PubMed2006

Sialolipoma of the hard palate.

Sialolipoma is a new variant of salivary gland lipoma, which was first proposed by Nagao et al. (Histopathology 2001; 38: 30) in 2001. We report this rare case of sialolipoma in the hard palate. A 60-year-old Japanese woman was referred to our department complaining of a painless swelling on the right side of the hard palate. Intra-oral examination revealed a soft, elastic, dome-shaped mass with 1 cm in diameter located in the posterior part of the hard palate. Magnetic resonance imaging examination revealed high intensity on T(1)-weighted image and isointensity on T(2)-weighted image. Incisional biopsy revealed that the tumor was encapsulated by fibrous tissue, consisted of adipose tissue, and also contained normal salivary gland tissue peripherally. First diagnosed as an ordinary lipoma of the hard palate, the tumor was excised. According to the recent criteria of histologic findings of sialolipoma, we rediagnosed the tumor as sialolipoma of the hard palate.

Diagnosis, Differential↗
PubMed2006

Multiple osseous dysplasia arising from impacted teeth: report of a case associated with odontogenic lesions.

We report a case of osseous dysplasia (OD) showing extremely rare clinical features. A 37-year-old Japanese woman was referred to our clinic complaining of a left alveolar bony swelling at an impacted canine. Radiographic examinations revealed a mixed radiopaque lesion involving the impacted left canine and also revealed an impacted left wisdom tooth with a cystic change and a clear radiopaque lesion suspected to be odontoma. All the extracted upper teeth and odontoma showed hypercementosis and the canine was fully involved in it. Histopathologically, they showed the same features and were diagnosed as OD. The findings of multiple OD from incompletely erupted teeth and odontoma in our case may well show that OD can arise from any tooth with periodontal ligaments and that focal OD can show expansive growth like the ossifying fibroma.

Adult↗
PubMed2003

Fibronectin requirement in branching morphogenesis.

Many organs, including salivary glands, lung and kidney, are formed during embryonic development by epithelial branching. In branching morphogenesis, repetitive epithelial cleft and bud formation create the complex three-dimensional branching structures characteristic of many organs. Although the mechanisms are poorly understood, one might involve the site-specific accumulation of some regulatory protein. Here we show that the extracellular matrix protein fibronectin is essential for cleft formation during the initiation of epithelial branching. Fibronectin messenger RNA and fibrils appeared transiently and focally in forming cleft regions of submandibular salivary-gland epithelia, accompanied by an adjacent loss of cadherin localization. Decreasing the fibronectin concentration by using small interfering RNA and inhibition by anti-fibronectin or anti-integrin antibodies blocked cleft formation and branching. Exogenous fibronectin accelerated cleft formation and branching. Similar effects of fibronectin suppression and augmentation were observed in developing lung and kidney. Mechanistic studies revealed that fibrillar fibronectin can induce cell-matrix adhesions on cultured human salivary epithelial cells with a local loss of cadherins at cell-cell junctions. Thus, fibronectin expression is required for cleft formation in branching morphogenesis associated with the conversion of cell-cell adhesions to cell-matrix adhesions.

Animals↗
PubMed2003

Role of PI 3-kinase and PIP3 in submandibular gland branching morphogenesis.

The mouse submandibular gland (SMG) epithelium undergoes extensive morphogenetic branching during embryonic development as the first step in the establishment of its glandular structure. However, the specific signaling pathways required for SMG branching morphogenesis are not well understood. Using E13 mouse SMG organ cultures, we showed that inhibitors of phosphatidylinositol 3-kinase (PI 3-kinase), wortmannin and LY294002, substantially inhibited branching morphogenesis in SMG. Branching morphogenesis of epithelial rudiments denuded of mesenchyme was inhibited similarly, indicating that PI 3-kinase inhibitors act directly on the epithelium. Immunostaining and Western analysis demonstrated that the p85 isoform of PI 3-kinase is expressed in epithelium at levels higher than in the mesenchyme. A target of PI 3-kinase, Akt/protein kinase B (PKB), showed decreased phosphorylation at Ser(473) by Western analysis in the presence of PI 3-kinase inhibitors. The major lipid product of PI 3-kinase, phosphatidylinositol 3,4,5-trisphosphate (PIP(3)), was added exogenously to SMG via a membrane-transporting carrier in the presence of PI 3-kinase inhibitors and was found to stimulate cleft formation, the first step of branching morphogenesis. Together, these data indicate that PI 3-kinase plays a role in the regulation of epithelial branching morphogenesis in mouse SMG acting through a PIP(3) pathway.

Androstadienes↗
PubMed2003

Neurotrophic effect of Semaphorin 4D in PC12 cells.

Semaphorins provide crucial attractive and repulsive cues involved in axon guidance during neural development. Out of them, Semaphorin 4D (Sema4D) is enriched in the nervous and immune tissues, and acts as proliferative and survival factors of peripheral lymphocytes in the immune system, but is poorly understood in the nervous system. By using PC12 cells which are well known to differentiate into neural cells in response to nerve growth factor (NGF), we found that soluble forms of Sema4D had neurotrophic effects which were inhibited by neutralizing antibodies to Sema4D. Sema4D strikingly potentiated neurite outgrowth in the presence of 50 ng/ml NGF and increased sensitivity to NGF. Cells responded to very low concentrations of NGF in the presence of 1 nM Sema4D. Activation of following signal proteins, protein kinase C (PKC), L-type of voltage-dependent Ca(2+) channel, and phosphatidylinositol (PI) 3-kinase mediated neurotrophic neurite-outgrowth action of Sema4D. These findings suggest a new function of Sema4D as a neurotrophic signal in PC12 cells.

Animals↗