Katsumi Nishijima

Functional modes of retinoic acid in mouse osteoblastic clone MC3T3-E1, proved as a target cell for retinoic acid

Mouse osteoblastic clone MC3T3‐E1 was proved as a target cell for retinoic acid (RA) in bone tissues through the demonstration of RA‐receptor gene expression by the northern blot analysis. The effect of RA on the cell growth of MC3T3‐E1 was repressive for both subconfluent and confluent growth, whereas RA enhancement of alkaline phosphatase expression was observed at the confluent stage. This implies that RA is a regulatory factor leading osteogenesis of the cells after the confluent stage. RA exhibited simultaneously the stage‐dependent effects on EGF‐dependent mitogenesis: promotive at the subconfluent, but repressive at the confluent stage.

Involvement of retinoic acid and its receptor β in differentiation of motoneurons in chick spinal cord

Retinoic acid is known to play an important role during development of central nervous system. In order to clarify function of retinoic acid during the development, we investigated expression pattern of the chick retinoic acid receptor subtype beta gene by an in situ hybridization method. We found that expression of the beta gene is localized in neural tube at stages 16-20, then is turned to be restricted to developing motoneurons at stages 23-29. These results suggested that retinoic acid and its receptor beta are involved in differentiation of the motoneurons in spinal cord.

Metaphyseal fibrous defect (nonossifying fibroma) in the mandible: A case report

A 7-year-old boy presented in whom a metaphyseal fibrous defect was diagnosed. The lesion was enucleated under local anesthesia. The postoperative course was uneventful and there have been no signs of recurrence as of 14 months after operation. Although rare, metaphyseal fibrous defect should be included in the differential diagnosis of tumors arising in the jaws.

Immunohistochemical demonstration of tenascin and fibronectin in odontogenic tumours and human fetal tooth germs

The distribution of tenascin and fibronectin (plasma fibronectin) was studied immunohistochemically in ameloblastomas, ameloblastic fibromas and ameloblastic carcinomas, as well as in tooth germs using monoclonal antibodies. Tenascin is an extracellular matrix molecule that was shown to be enriched in the embryonic mesenchyme surrounding the budding epithelium in various organs, including the tooth. Tenascin was strongly expressed in the basement membrane zone of the ameloblastomas and in the early tooth germ and the dental lamina, but not in the dental follicle. The expression of tenascin in the ameloblastic fibroma was seen in the basement membrane of the epithelial islands throughout the stromal tissues. There were clear differences in fibronectin expression in the follicular ameloblastoma and ameloblastic carcinoma. The results suggest that tenascin and fibronectin are involved in epithelial mesenchymal interactions of the tooth germ and in odontogenic tumours.

c-Fos induction in the rat spinal dorsal horn partially deafferented by dorsal rhizotomy

The 4th and 5th segments of the lumbar (the L4 and L5) dorsal horn receive primary input from the sciatic receptive fields through the L4 and L5 dorsal roots. Noxious stimulation of the hindpaw with formalin induces c-Fos in neurons in superficial laminae (I and II) of these dorsal horn segments. Rhizotomy of the L5 dorsal root 2 days before stimulation resulted in a marked reduction in the number of neurons with c-Fos protein-like immunoreactivity (fos-neurons). At 3 weeks after the L5 rhizotomy, the number of fos-neurons in laminae I and II significantly increased compared to that at 2 days post-rhizotomy. This result indicates that chronic partial deafferentation by dorsal rhizotomy increases responsiveness of superficial dorsal horn neurons to spared primary input.

Cooperative Activation of HoxD Homeobox Genes by Factors from the Polarizing Region and the Apical Ridge in Chick Limb Morphogenesis

When a mouse zone of polarizing activity (ZPA) at the posterior margin of the limb bud was grafted into the anterior margin of the chick limb bud, the expressions of the chick homeobox genes HoxD12 and D13 were induced prior to the formation of chick extra digits. This induction was observed in a restricted domain close to both the grafted mouse ZPA and the chick apical ectodermal ridge (AER). When the posterior half of the AER was removed, the normal expression was diminished in the distaloposterior region. Thus, it is likely that at least two distinct factors, one from the ZPA and the other from the AER, act cooperatively to provide positional information to induce the sequential expression of the HoxD genes.

Disruption and restoration of dorsal horn sensory map after peripheral nerve crush and regeneration

&NA; Formalin injection into the hindpaw of rats produces many neurons with c‐fos protein‐like immunoreactivity (fos‐neurons) in the medial Symbol of the ipsilateral dorsal horn laminae I and II at the junction of 4th and 5th lumbar segments (the sciatic territory). The tibial nerve transection 2 or 3 days earlier resulted in almost complete elimination of stimulation‐induced fos‐neurons in the tibial territory (medial Symbol of the sciatic territory). When the animals had been conditioned by crushing the tibial nerve 2 weeks before stimulation (11 or 12 days before transection), the number of fos‐neurons significantly increased compared to simple transection alone. The increase (2.5‐fold) was greatest in the tibial territory. Therefore, the dorsal horn neurons in the deafferented tibial territory exhibited hypersensitivity to intact peroneal primary input, and the somatotopy map was disrupted. When the nerve had been crushed 3 weeks (18 or 19 days earlier than transection) rather than 2 weeks before stimulation, however, the number and distribution of fos‐neurons were not different from those without conditioning (transection alone). Regenerated tibial nerve fibers were capable of transganglionic transport of WGA‐HRP from the hindpaw receptive field to the tibial territory of the dorsal horn by 3 weeks but not by 2 weeks following the nerve crush. When transection was omitted, noxious signal transmitted through the tibial nerve fibers regenerated by 3 weeks after crush was capable of inducing c‐fos in the tibial territory. The injury‐induced hypersensitivity of dorsal horn neurons and resulting disruption of somatotopy map were reversed by re‐establishment of peripheral tissue‐nerve interaction. Symbol. No caption available Symbol. No caption available

An experimental study of the osteogenicity of free periosteal allografts with cyclosporine A administration

Free tibial periosteum was grafted onto the dorsum (m. cutaneous trunci) of Sprague-Dawley rats to examine its osteogenic potential. The animals were divided into 3 groups based on type of: A. autogenous periosteum, B. allogeneic periosteum and C. allogeneic periosteum, and treated with cyclosporine A immunosuppression. The osteogenic response was evaluated radiologically and histologically. This study indicates that in this model periosteal allografts with immunosuppression of the recipient result in osteogenesis. Clinical application of the technique will only be possible if immunosuppressive methods with minimal morbidity are developed so that they can be used for prolonged periods.

A case of a relatively large neurilemmoma found in the left cheek.

神経鞘腫は神経原性の良性腫瘍で顎口腔領域に好発すると言われている。われわれは比較的まれな左側頬部に発生した80×50×30mmの大きさの本腫瘍を経験した。本症例は顔貌の非対称, X線写真上で上顎の吸収が見られ, 病理学的にAntoni分類の混在型であった。過去30年間に本邦で報告された頬部から翼口蓋窩, 側頭下窩にかけて発生した神経鞘腫は女性に多く, 平均年齢は37.7歳で, 病理学的には混在型が多かった。

Pediatric acute lymphocytic leukemia with osseous changes in jaws: Literature review and report of a case

A case of acute lymphocytic leukemia (ALL) in a child is presented. We also reviewed the recent literature of similar cases describing leukemic jaw bones involvement in Japan. Radiographic examinations of the patient disclosed diffuse osteolytic changes of the entire jaws, the corticated border of the crypts of developing teeth, loss of lamina dura, a thickened periodontal space and disappearance of the radiopaque lines that delineate the borders of the mandibular canal. Pronounced regression and restoration of the alveolar bone and the crypts were detectable on the radiographs taken after a course of the treatment for ALL.An apparent radiographic change of jaw bone after the treatment indicates that the radiographic examinations of children with leukemia in the leukemic process are of quite diagnostic value.