Shoji Enomoto

Negative feedback regulation of ASK1 by protein phosphatase 5 (PP5) in response to oxidative stress

Apoptosis signal‐regulating kinase 1 (ASK1) is a MAP kinase kinase kinase (MAPKKK) that activates the JNK and p38 MAP kinase cascades and is activated in response to oxidative stress such as hydrogen peroxide (H2O2). A yeast two‐hybrid screening identified a serine/threonine protein phosphatase 5 (PP5) as a binding partner of ASK1. PP5 directly dephosphorylated an essential phospho‐threonine residue within the kinase domain of ASK1 and thereby inactivated ASK1 activity in vitro and in vivo. The interaction between PP5 and ASK1 was induced by H2O2 treatment and was followed by the decrease in ASK1 activity. PP5 inhibited not only H2O2‐induced sustained activation of ASK1 but also ASK1‐dependent apoptosis. Thus, PP5 appears to act as a physiological inhibitor of ASK1–JNK/p38 pathways by negative feedback.

Evaluation of ceramics composed of different hydroxyapatite to tricalcium phosphate ratios as carriers for rhBMP-2

We have investigated pellet-shaped implants prepared from biphasic calcium phosphate (BCP) ceramics with five different ratios of hydroxyapatite (HAP) to beta tricalcium phosphate (beta-TCP). The purpose of this study was to evaluate these BCP ceramics as carriers for rhBMP-2. BCP ceramics impregnated with the different doses of recombinant human bone morphogenetic protein 2 (rhBMP-2) (1, 5 and 10g) were used for the experimental purpose and the ceramics without rhBMP-2 were used as control. The pellets were placed into subcutaneous pockets on the dorsum of 4-week-old male Wistar rats. The animals were sacrificed 2 and 4 weeks after implantation. Bone induction was estimated by alkaline phosphatase (ALP) activity measured at 2 weeks after implantation. Pellets were also examined radiologically, histologically and histomorphometrically. The results showed that all experimental pellets exhibited new bone formation whereas the control pellets produced only fibrous connective tissue. Here, 100% HAP ceramic showed most amount of bone formation, whereas 25% HAP to 75% TCP ceramic produced the bone least in amount among different BCP ceramics at the end of 4 weeks. This study indicates that formation of new bone depends on the ceramic content with high HAP-TCP ratio and high dose of rhBMP-2.

The Novel Gene Encoding a Putative Transmembrane Protein Is Mutated in Gnathodiaphyseal Dysplasia (GDD)

Gnathodiaphyseal dysplasia (GDD) is a rare skeletal syndrome characterized by bone fragility, sclerosis of tubular bones, and cemento-osseous lesions of the jawbone. By linkage analysis of a large Japanese family with GDD, we previously mapped the GDD locus to chromosome 11p14.3-15.1. In the critical region determined by recombination mapping, we identified a novel gene (GDD1) that encodes a 913-amino-acid protein containing eight putative transmembrane-spanning domains. Two missense mutations (C356R and C356G) of GDD1 were identified in the two families with GDD (the original Japanese family and a new African American family), and both missense mutations occur at the cysteine residue at amino acid 356, which is evolutionarily conserved among human, mouse, zebrafish, fruit fly, and mosquito. Cellular localization to the endoplasmic reticulum suggests a role for GDD1 in the regulation of intracellular calcium homeostasis.

Measure of bite force and occlusal contact area before and after bilateral sagittal split ramus osteotomy of the mandible using a new pressure-sensitive device: A preliminary report

PURPOSE This study examined bite force and occlusal contact area in prognathic patients before and after bilateral sagittal split ramus osteotomy of the mandible using a newly developed pressure-sensitive sheet (Dental-Prescale, Fuji Photo Film Co, Tokyo, Japan). PATIENTS AND METHODS Twenty-five prognathic patients were examined. Bite force and occlusal contact area were measured preoperatively, at 2, 4, and 8 weeks, and at 3 and 6 months after surgery. The bite force and occlusal contact area of 20 healthy subjects were also measured. RESULTS Both bite force and occlusal contact area of the patients were the lowest 2 weeks after surgery and recovered to the preoperative level between 8 weeks and 3 months. Subsequently, they increased slowly and exceeded the preoperative level at 6 months after surgery. However, even at 6 months, both the bite force and the occlusal contact area of the patients were still only about half or less than that of healthy subjects. CONCLUSION This pressure-sensitive device can be used as a simple indicator of postoperative recovery and occlusal improvement in patients following orthognathic surgery.

Comparative study of biphasic calcium phosphate ceramics impregnated with rhBMP-2 as bone substitutes

We investigated pellet-shaped implants prepared from biphasic calcium phosphate (BCP) ceramics with five different ratios of hydroxyapatite (HAP) to beta-tricalcium phosphate (beta-TCP) to evaluate these ceramics as bone substitutes. BCP ceramics impregnated with different doses of recombinant human bone morphogenetic protein 2 (rhBMP-2) (1, 5, and 10 microg) were used for experimental purposes and ceramics without rhBMP-2 were used for control. The pellets were implanted under the pericranium in adult Wistar male rats and were harvested 8 weeks after implantation. The retrieved pellets were then examined radiologically, histologically, and histomorphometrically. The results revealed that the pellets treated with rhBMP-2 exhibited new bone and bone marrow, whereas control pellets produced fibrous connective tissues. The formation of new bone induced by rhBMP-2 was dose dependent. The extent of bone and bone marrow formation and the degree of resorption of the ceramic particles were significantly higher in the pellets composed of 25% HAP-75% TCP. In this study, bioresorption of the ceramic produced favorable conditions for rhBMP-2-induced bone formation.

Stability after surgical correction of mandibular prognathism using the sagittal split ramus osteotomy and fixation with poly-L-lactic acid (PLLA) screws☆

PURPOSE This study was designed to examine skeletal stability after surgical correction of mandibular prognathism using a sagittal split ramus osteotomy (SSRO) and fixation with poly-L-lactic acid (PLLA) screws. PATIENTS AND METHODS Twenty patients with Class III malocclusion were treated with bilateral SSRO and mandibular setback. Ten underwent fixation with titanium screws (group I) and the other 10 with PLLA screws (group II). Cephalograms were obtained 2 or 3 days postoperatively, and at 3, 6, and 12 months after the operation. Changes in the position of upper incisors (U-1), lower incisors (L-1), B-point, and pogonion were examined on lateral cephalograms. RESULTS Certain tendencies for overjet and overbite were noted to have decreased more markedly, and changes in the position of the skeletal points were greater in group II than in group I. However, statistical analysis showed no significant differences between the two groups. CONCLUSION Our results suggest that fixation of the bony segments with PLLA screws after SSRO may be used effectively in properly selected cases.

1α,25-Dihydroxyvitamin D3 receptors and their action in embryonic chick chondrocytes

SummaryThe role of vitamin D in the maturation of epiphyseal chondrocytes was investigated in the developing chick embryo. Cartilage tissues were divided into two parts: resting cartilage and growth cartilage. A cytosol component to which 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) is specifically bound first appeared in the growth cartilage on day 15, rapidly increased, and attained a maximum on day 19. The calcium content of the growth cartilage also began to increase on day 15 and continued to increase in parallel with the 1α,25(OH)2D3 receptor levels. Glycosaminoglycan (GAG) synthesis by the growth cartilage cells increased from day 11–17 and rapidly declined thereafter reciprocally with the increase in calcium and receptor levels. In the resting cartilage, no cytosol receptor for 1α,25(OH)2D3 was detected up to hatching time. The calcium content and GAG synthesis in the resting cartilage were very low and did not change appreciably throughout development. No receptor-like macromolecule for 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) was recognized in either the resting or growth cartilage. 1α,25(OH)2D3 added to the culture of chondrocytes from the epiphyseal growth cartilage inhibited GAG synthesis and stimulated its release from the cell layer into the medium in a dose-dependent manner. Thesein vitro effects of 1α,25(OH)2D3 were not observed in chondrocytes obtained from 13-day-old growth cartilage and 19-day-old resting cartilage. 25-Hydroxyvitamin D3 and 24R,25(OH)2D3 had no effect on chondrocytes in any of the preparations. These results suggest that 1α,25(OH)2D3 is directly involved in the maturation of chondrocytes and possibly in the calcification of growth cartilage.

Heterogeneity in the gingival fibromatoses.

Forty‐nine cases of isolated familial and idiopathic gingival fibromatoses, consisting of 12 cases from six families and 37 cases of idiopathic gingival fibromatosis, were reviewed. Pedigrees of five families revealed various penetrances and genetic heterogeneity as suggested by the presence of both autosomal dominant and autosomal recessive inheritances. Ultrastructurally, the lesions were composed of fibroblast‐like cells and myofibroblast‐like cells, with the former being the predominant cell type. The 267 cases of familial and idiopathic gingival fibromatoses were analyzed, and they with or without hypertrichosis, mental retardation, and/or epilepsy. These included 49 cases seen by the authors, 50 cases from the Japanese literature, and 168 cases from non‐Japanese literature. Isolated gingival fibromatosis occurred more frequently after age of 12 years (P < 0.007). There was no significant difference in age of onset between generalized and localized forms of the idiopathic gingival fibromatosis. Gingival fibromatosis with hypertrichosis and mental retardation and/or epilepsy occurred frequently before 12 years (P < 0.069). It has been shown that heterogeneity of the gingival fibromatosis is a result of either histologic heterogeneity, genetic heterogeneity, or a combination with other systemic disorders. Cancer 68:2202–2212, 1991.

Blockade of CTLA-4 Signals Inhibits Th2-Mediated Murine Chronic Graft-Versus-Host Disease by an Enhanced Expansion of Regulatory CD8+ T Cells

CTLA-4 (CD152) is thought to be a negative regulator of T cell activation. Little is known about the function of CTLA-4 in Th2-type immune responses. We have investigated the effect of initial treatment with anti-CTLA-4 mAb on murine chronic graft-vs-host disease. Transfer of parental BALB/c splenocytes into C57BL/6 × BALB/c F1 mice induced serum IgE production, IL-4 expression by donor CD4+ T cells, and host allo-Ag-specific IgG1 production at 6–9 wk after transfer. Treatment with anti-CTLA-4 mAb for the initial 2 wk significantly reduced IgE and IgG1 production and IL-4 expression. Analysis of the splenic phenotype revealed the enhancement of donor T cell expansion, especially within the CD8 subset, and the elimination of host cells early after anti-CTLA-4 mAb treatment. This treatment did not affect early IFN-γ expression by CD4+ and CD8+ T cells and anti-host cytolytic activity. Thus, blockade of CTLA-4 greatly enhanced CD8+ T cell expansion, and this may result in the regulation of consequent Th2-mediated humoral immune responses. These findings suggest a new approach for regulating IgE-mediated allergic immune responses by blockade of CTLA-4 during a critical period of Ag sensitization.

Grafting of the buccal fat pad into palatal defects.

Grafting of the buccal fat pad was performed in combination with lyophilized porcine dermis in six cases of palatal defects. The use of lyophilized porcine dermis not only simplified the surgical procedure but also permitted a proper prosthetic rehabilitation. This technique proved to have more advantages for palatal defects.