Evaluation of Various Polishing Systems for Lithium Disilicate Glass-Ceramics.

OBJECTIVE: The aim of this study was to investigate the surface roughness of lithium disilicates (LS2s) polished using various polishing systems. MATERIALS AND METHODS: Two types of LS2 (A, Amber Mill and E, IPS e.max CAD) were polished using LS2-specific polishing systems (L-Edenta, L-Jota), a zirconia-specific polishing system (Z-Jota), and a conventional ceramic polishing system (P-Shofu) (n = 8 per group). The compositions of different polishing systems were analyzed using EDS. Surface roughness was measured using confocal laser scanning microscopy and analyzed using EDS and SEM. ANOVA and Tukey's tests were used for the statistical analyses (p = 0.05). RESULTS: The polishing systems were mainly composed of C, O, and Si. The L-Jota group exhibited rougher surfaces than the other groups. Amber Mill exhibited higher surface roughness than IPS e.max CAD (p⟨0.001). Among the polishing systems, the L-Jota group presented the highest roughness value (pp⟨0.001). The surface roughness of the AL-Jota group was higher than that of the other groups. CONCLUSIONS: A sufficiently smooth surface can be achieved without a LS2-specific polishing system. Further, the same polishing system can have different effects depending on the type of LS2.

NAMPT Is an Essential Regulator of RA-Mediated Periodontal Inflammation.

Recent studies have indicated a potential correlation between rheumatoid arthritis (RA) and periodontal inflammation. We undertook this study to verify whether RA mediates periodontitis-like phenotypes in experimental mouse models of RA and to explore the role of nicotinamide phosphoribosyltransferase (NAMPT) in periodontal inflammation during RA pathogenesis. Periodontal inflammation and alveolar bone loss have been reported in mice with collagen-induced arthritis (CIA) and in genetically modified tumor necrosis factor-α (TNF-α) transgenic (TG) mouse models. Among the adipokines examined in our study, NAMPT expression was markedly upregulated in the periodontal ligament (PDL) tissues in RA mouse models and in human PDL cells stimulated by the proinflammatory cytokines, interleukin (IL) 1ß and TNF-α. When NAMPT was overexpressed with the Nampt-synthesizing adenovirus vector (Ad- Nampt), the PDL cells exhibited an increased expression of cytokines (IL6), chemokines (IL8 and chemokine [C-C motif] ligand 5 [CCL5]), inflammatory mediators (cyclooxygenase 2 [COX-2]), and matrix-degrading enzymes (matrix metalloproteinase [MMP] 1 and MMP3). Inhibition of NAMPT by the intracellular NAMPT (iNAMPT) inhibitor, FK866, or by the sirtuin inhibitor, nicotinamide, in PDL cells led to inhibition of the IL1ß or Ad- Nampt-induced upregulation of catabolic factors, whereas treatment with recombinant NAMPT protein or blockade of extracellular NAMPT (eNAMPT) with blocking antibody did not. Moreover, NAMPT inhibition by the intraperitoneal or intragingival injection of FK866 in CIA mice inhibited periodontal tissue damage, under conditions of RA. Thus, our results verified the co-occurrence of RA and periodontal inflammation using experimental mouse models of RA, suggesting that iNAMPT in PDL cells plays a pivotal role in the pathogenesis of RA-mediated periodontal inflammation by regulating the expression levels of catabolic genes, such as IL6, IL8, CCL5, COX-2, MMP1, and MMP3.

Decreased H3K27 and H3K4 trimethylation on mortal chromosomes in distributed stem cells.

The role of immortal DNA strands that co-segregate during mitosis of asymmetrically self-renewing distributed stem cells (DSCs) is unknown. Previously, investigation of immortal DNA strand function and molecular mechanisms responsible for their nonrandom co-segregation was precluded by difficulty in identifying DSCs and immortal DNA strands. Here, we report the use of two technological innovations, selective DSC expansion and establishment of H2A.Z chromosomal asymmetry as a specific marker of 'immortal chromosomes,' to investigate molecular properties of immortal chromosomes and opposing 'mortal chromosomes' in cultured mouse hair follicle DSCs. Although detection of the respective suppressive and activating H3K27me3 and H3K4me3 epigenetic marks on immortal chromosomes was similar to randomly segregated chromosomes, detection of both was lower on mortal chromosomes destined for lineage-committed sister cells. This global epigenomic feature of nonrandom co-segregation may reveal a mechanism that maintains an epigenome-wide 'poised' transcription state, which preserves DSC identity, while simultaneously activating sister chromosomes for differentiation.

Hypoxia-inducible factor-2α regulates Fas-mediated chondrocyte apoptosis during osteoarthritic cartilage destruction.

Apoptosis of articular chondrocytes is associated with the pathogenesis of osteoarthritis (OA). Recently, we demonstrated that hypoxia-inducible factor (HIF)-2α, encoded by Epas1, causes OA cartilage destruction by regulating the expression of various matrix-degrading enzymes. Here, we investigated the involvement of HIF-2α in chondrocyte apoptosis and OA cartilage destruction. HIF-2α levels in human and mouse OA chondrocytes were markedly elevated in association with increased apoptosis of articular chondrocytes. Overexpression or knockdown of HIF-2α alone did not cause chondrocyte apoptosis. However, HIF-2α expression markedly increased chondrocyte apoptosis in the presence of an agonistic anti-Fas (CD95) antibody. HIF-2α enhanced Fas expression and potentiated downstream signaling pathways, increasing the activity of initiator and executioner caspases. Overexpression of HIF-2α in mouse cartilage tissue, either by intra-articular injection of Epas1 adenovirus (Ad-Epas1) or in the context of chondrocyte-specific Epas1 transgenic mice, increased chondrocyte apoptosis and cartilage destruction. In contrast, chondrocyte-specific knockout of Epas1 in mice suppressed DMM (destabilization of the medial meniscus)-induced chondrocyte apoptosis and inhibited OA cartilage destruction. Moreover, Fas-deficient mice exhibited diminished chondrocyte apoptosis and OA cartilage destruction in response to Ad-Epas1 injection or DMM surgery. Taken together, our results demonstrate that HIF-2α potentiates Fas-mediated chondrocyte apoptosis, which is associated with OA cartilage destruction.

Localization of three types of the inositol 1,4,5-trisphosphate receptor/Ca(2+) channel in the secretory granules and coupling with the Ca(2+) storage proteins chromogranins A and B.

Although the role of secretory granules as the inositol 1,4,5-trisphosphate (IP(3))-sensitive intracellular Ca(2+) store and the presence of the IP(3) receptor (IP(3)R)/Ca(2+) channel on the secretory granule membrane have been established, the identity of the IP(3)R types present in the secretory granules is not known. We have therefore investigated the presence of different types of IP(3)R in the secretory granules of bovine adrenal medullary chromaffin cells using immunogold electron microscopy and found the existence of all three types of IP(3)R in the secretory granules. To determine whether these IP(3)Rs interact with CGA and CGB, each IP(3)R isoform was co-transfected with CGA or CGB into NIH3T3 or COS-7 cells, and the expressed IP(3)R isoform and CGA or CGB were co-immunoprecipitated. From these studies it was shown that all three types of IP(3)R form complexes with CGA and CGB in the cells. To further confirm whether the IP(3)R isoforms and CGA and CGB form a complex in the secretory granules the potential interaction between all three isoforms of IP(3)R and CGA and CGB was tested by co-immunoprecipitation experiments of the mixture of secretory granule lysates and the granule membrane proteins. The three isoforms of IP(3)R were shown to form complexes with CGA and CGB, indicating the complex formation between the three isoforms of IP(3)R and CGA and CGB in the secretory granules. Moreover, the pH-dependent Ca(2+) binding property of CGB was also studied using purified recombinant CGB, and it was shown that CGB bound 93 mol of Ca(2+)/mol with a dissociation constant (K(d)) of 1.5 mm at pH 5.5 but virtually no Ca(2+) at pH 7.5. The high capacity, low affinity Ca(2+)-binding property of CGB at pH 5.5 is comparable with that of CGA and is in line with its role as a Ca(2+) storage protein in the secretory granules.