Bone metabolism results from a balance between osteoclast-driven bone resorption and osteoblastmediated bone formation. Diseases such as periodontitis and rheumatoid arthritis are characterized by increased bone destruction due to enhanced osteoclastogenesis 1,2 . Here we report that interferon regulatory factor 8 (IRF8), a transcription factor expressed in immune cells, is a key regulatory molecule for osteoclastogenesis. IRF8 expression in osteoclast precursors was downregulated during the initial phase of osteoclast differentiation induced by receptor activator of nuclear factor κB ligand (RANKL, also called TRANCE, ODF, and OPGL), which is encoded by the Tnfsf11 gene. Mice deficient in IRF8 exhibited severe osteoporosis due to increased numbers of osteoclasts, and enhanced bone destruction following lipopolysaccharide (LPS) administration. Irf8 -/-osteoclast precursors underwent increased osteoclastogenesis in response to RANKL and tumor necrosis factor α (TNFα). IRF8 suppressed osteoclastogenesis by inhibiting the function and expression of nuclear factor of activated T cells c1 (NFATc1). Our results show that IRF8 inhibits osteoclast formation Correspondence should be addressed to M.T. (takami@dent.showa-u.ac.jp). AUTHOR CONTRIBUTIONS B.Z. performed most of the experiments with significant assistance from M.T. X.W. conducted the histological analysis. A.Y., T.K., X.H., and T.T. assisted with the experiments. K.O. provided the Irf8 −/− mice. B.Z. and M.T. designed the project and wrote the manuscript. Y.C. provided recombinant RANKL and contributed to manuscript preparation. L.B.I. oversaw the bone marrow chimera and human cell experiments and contributed to manuscript revision. H.T. oversaw the inflammatory bone destruction experiments and provided critical advice for the experiments. M.T. and R.K. supervised the project. COMPETING INTERESTS STATEMENTThe authors declare that they have no competing financial interests. [3][4][5] . Numerous studies have focused on these upregulated genes and their roles in osteoclastogenesis. On the other hand, the expression levels of various genes are simultaneously downregulated during osteoclastogenesis 6 . The biological significance of the downregulated expression of these genes following RANK activation, however, has not been fully elucidated. NIH Public AccessTo identify genes that show reduced expression levels in response to RANK signaling, we performed a genome-wide screening of mRNAs from osteoclast precursors and osteoclasts using a DNA microarray technique (data not shown). Among the identified genes, expression of the transcription factor Irf8 [also called interferon consensus sequence binding protein (ICSBP)] was found to be downregulated during the initial phase of osteoclastogenesis triggered by RANKL (data not shown). IRF8 is known to be specifically expressed in immune cells, including monocytes/macrophages, B lymphocytes, and activated T lymphocytes 7-9 . It is a member of the IRF family and has been shown to regulate myeloid cell development by...

These results indicate that the diode laser is useful for removing smear layer and debris from root canal walls, and reducing apical leakage after obturation in vitro, and suggest that it would be useful for root canal treatment in clinic.

This study investigates the healing process that takes place in the bone and soft tissue of the maxilla and the mandible after perforation by an Er,Cr:YSGG laser device. The jaws of New Zealand white rabbits were irradiated with an Er,Cr:YSGG laser, forming wounds 0.4 mm in diameter. Irradiation parameters were as follows: repetition rate was 20 pulse/s, pulse duration was 140-200 micros, power was 2 W, exposure time was 10 s, energy density was 80 J/cm(2). After sacrifice at 0-56 days post-surgery, gross observations and histological examinations were performed. Effective hemostasis was achieved after Er,Cr:YSGG laser surgery. There was a minimal delay before the healing began. After 56 days all of the bone defects had been completely replaced by new bone. In conclusion, the Er,Cr:YSGG laser allows precise surgical ablation with minimal thermal damage to adjacent tissues in vivo. The overall subsequent healing was favorable. This laser may potentially be used in minor oral surgery.

Croceicoccus marinus gen. nov., sp. nov., a yellow-pigmented bacterium from deep-sea sediment, and emended description of the family Erythrobacteraceae A Gram-negative, aerobic, neutrophilic, coccoid bacterium, strain E4A9 T , was isolated from a deep-sea sediment sample collected from the East Pacific polymetallic nodule region. 16S rRNA gene sequence analysis showed that the isolate was related to the type strain of Altererythrobacter epoxidivorans (96.0 % sequence similarity). Lower 16S rRNA gene sequence similarities were observed with other members of the genera Altererythrobacter (94.7 %), Erythrobacter (94.0-95.4 %), Erythromicrobium (94.8 %) and Porphyrobacter (94.6-95.1 %) of the family Erythrobacteraceae. Phylogenetic analysis including all described species of the family Erythrobacteraceae and several members of the family Sphingomonadaceae revealed that the isolate formed a distinct phylogenetic lineage with the family Erythrobacteraceae. Chemotaxonomic analysis revealed ubiquinone-10 as the predominant respiratory quinone, anteiso-C 15 : 0 , iso-C 14 : 0 and iso-C 15 : 0 as major fatty acids, and phosphatidylglycerol as the major polar lipid. The DNA G+C content was 71.5 mol%. The isolate contained carotenoids, but no bacteriochlorophyll a. On the basis of phenotypic and genotypic data presented in this study, strain E4A9 T represents a novel species in a new genus in the family Erythrobacteraceae for which the name Croceicoccus marinus gen. nov., sp. nov. is proposed; the type strain is E4A9 T (5CGMCC 1.6776 T 5JCM 14846 T ).The family Erythrobacteraceae (order Sphingomonadales, class Alphaproteobacteria) was proposed by Lee et al. (2005) based on a comprehensive phylogenetic analysis and, at present, it comprises four recognized genera: Altererythrobacter (Kwon et al., 2007), Erythrobacter (Shiba & Simidu, 1982), Erythromicrobium (Yurkov et al., 1994) and Porphyrobacter (Fuerst et al., 1993).Members of the family Erythrobacteraceae are aerobic and produce pink, orange or yellow pigments. Ubiquinone-10 is the major respiratory quinone. Most species in the family have been isolated from various aquatic environments such as freshwater, seawater, marine mats or sediment, a hot spring, seaweed, a starfish and coral (Shiba & Simidu, 1982; Fuerst et al., 1993;Yurkov et al., 1994; Hanada et al., 1997; Denner et al., 2002; Hiraishi et al., 2002;Rainey et al., 2003;Yoon et al., 2003Yoon et al., , 2004a Yoon et al., , b, 2005a Yoon et al., , b, 2006Ivanova et al., 2005;Kwon et al., 2007). This study focuses on the description of strain E4A9 T , isolated from a deep-sea sediment sample. Based on the taxonomic data, it is proposed that this strain be included in a new genus within the family Erythrobacteraceae.The deep-sea sediment samples were collected by a multicorer from the East Pacific polymetallic nodule region (8 u 229 380 N 145 u 239 560 W) at a depth of Abbreviation: BChl a, bacteriochlorophyll a.The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain E4A9 T is EF62399...

The purpose of this study was to examine the histopathological response of dental pulp tissue to enamel matrix derivative (EMD) used as a pulp capping material. Thirty-two teeth from two mongrel dogs were divided into four equal groups. One group served as controls, and the others were used for deep Class V cavity preparation followed by direct pulp capping with enamel matrix derivative. The treated teeth were extracted after 1, 4, and 8 weeks and prepared for histopathological examination by light microscopy. All teeth prepared after 4 and 8 weeks demonstrated an increase in tertiary dentin, suggesting that enamel matrix derivative exerts a considerable influence on odontoblasts and endothelial cells of capillaries in dental pulp tissue. These results imply that enamel matrix derivative used as a pulp capping material may play a role in the calcification of dental pulp tissue.