Abstract Condylar resorption occurs in some cases after orthognathic surgery, and the risk factors associated with postoperative condylar head resorption have been extensively described. ...Nevertheless, even in cases with a combination of risk factors, postoperative condylar resorption may not appear. This study analyzed the microstructure and three-dimensional positional change of the condylar bone via imaging in patients who have undergone bimaxillary orthognathic surgery to determine whether the microstructure or condylar position differs between patients with and without postoperative condylar resorption. Among asymptomatic patients who underwent bimaxillary surgery between April 2021 and March 2022 at our department, 17 patients were analyzed, limited to “female,” “skeletal Class II,” and “high-angle cases,” which are known risk factors for mandibular head resorption. Multidetector computed tomography was performed on these patients before and 6 months after surgery, and the bone microstructure of the condylar head and the three-dimensional positional changes of the condylar bone and the proximal bony fragments were compared with the presence of postoperative condyle resorption using the bone morphology software TRI/3D-BON. Patients with condylar bone abnormalities before surgery and those with high trabecular bone density can develop postoperative resorption if the condyle is misaligned by surgery.
Carbon nanotubes (CNTs) have solid lubricity due to their unique structure, and as such, CNT composites are also expected to exhibit superior tribological properties. In this study, Co/CNT composite ...films were fabricated using a composite electrodeposition technique, and their tribological properties were investigated. Three different sizes of multiwalled carbon nanotubes (MWCNTs) were used as the CNTs in this study. The microstructures of the composite films were examined using scanning electron microscopy. Frictional and wear properties were examined using a ball-on-disk method without any lubricants at room temperature and at high temperatures (100–500°C). The Co/MWCNT composite films had lower coefficients of friction than a cobalt film at room temperature. In contrast, the coefficients of friction of the Co/MWCNT composite film at high temperature became higher than that at room temperature and slightly lower than that of a cobalt film. These results are likely related to the formation of cobalt oxides on the surface and the heat dissipation of the MWCNTs.
•The tribological properties of Co/MWCNT composite films were evaluated at various temperatures.•Co/MWCNT composite films exhibited lower coefficients of friction than cobalt film at room temperature.•The coefficients of friction of Co/MWCNT composite films increased with the temperature.
Paget's disease (PD) is characterized by increased numbers of abnormal osteoclasts (OCLs) that drive exuberant bone formation, but the mechanisms responsible for the increased bone formation remain ...unclear. We previously reported that OCLs from 70% of PD patients express measles virus nucleocapsid protein (MVNP), and that transgenic mice with targeted expression of MVNP in OCLs (MVNP mice) develop bone lesions and abnormal OCLs characteristic of PD. In this report, we examined if OCL‐derived sphingosine‐1‐phosphate (S1P) contributed to the abnormal bone formation in PD, since OCL‐derived S1P can act as a coupling factor to increase normal bone formation via binding S1P‐receptor‐3 (S1PR3) on osteoblasts (OBs). We report that OCLs from MVNP mice and PD patients expressed high levels of sphingosine kinase‐1 (SphK‐1) compared with wild‐type (WT) mouse and normal donor OCLs. SphK‐1 production by MVNP‐OCLs was interleukin‐6 (IL‐6)‐dependent since OCLs from MVNP/IL‐6−/− mice expressed lower levels of SphK‐1. Immunohistochemistry of bone biopsies from a normal donor, a PD patient, WT and MVNP mice confirmed increased expression levels of SphK‐1 in OCLs and S1PR3 in OBs of the PD patient and MVNP mice compared with normal donor and WT mice. Further, MVNP‐OCLs cocultured with OBs from MVNP or WT mice increased OB‐S1PR3 expression and enhanced expression of OB differentiation markers in MVNP‐OBs precursors compared with WT‐OBs, which was mediated by IL‐6 and insulin‐like growth factor 1 secreted by MVNP‐OCLs. Finally, the addition of an S1PR3 antagonist (VPC23019) to WT or MVNP‐OBs treated with WT and MVNP‐OCL‐conditioned media (CM) blocked enhanced OB differentiation of MVNP‐OBs treated with MVNP‐OCL‐CM. In contrast, the addition of the SIPR3 agonist, VPC24191, to the cultures enhanced osterix and Col‐1A expression in MVNP‐OBs treated with MVNP‐OCL‐CM compared with WT‐OBs treated with WT‐OCL‐CM. These results suggest that IL‐6 produced by PD‐OCLs increases S1P in OCLs and S1PR3 on OBs, to increase bone formation in PD.
Model for the effects of sphingosine kinase‐1/sphingosine‐1‐phosphate/S1P‐receptor‐3 (SphK‐1/S1P/S1PR3) in abnormal bone remodeling in Paget's disease (PD). Measles virus nucleocapsid protein (MVNP) in PD‐osteoclasts (OCLs) induces interleukin‐6 (IL‐6), which upregulates insulin‐like growth factor 1 (IGF‐1) and Sphk1. SphK‐1 enhances S1P levels in OCLs, and IL‐6 and IGF‐1 increase S1PR3 on osteoblast (OBs). S1P then increases OB differentiation and bone formation via enhanced S1PR3 expression on OBs.
Objectives
This study used cone beam computed tomography (CBCT) images to comparatively evaluate the three-dimensional microstructural features of reconstructed bone bridge based on the bone ...harvesting site and the presence/absence of artificial bone material, as well as the features of regenerated bone tissue after bone harvesting from mandibular symphysis in secondary alveolar bone grafting (SABG) for patients with cleft lip, with or without cleft palate.
Materials and methods
Thirty-one patients were divided into three groups in which SABG was performed by autologous bone harvesting from iliac crest (IC), mandibular symphysis (MS), or MS combined with β-TCP granules (MS+TCP). The microstructural trabecular bone parameters (TBPs) and bone structure indexes (SIs) were analyzed using datasets of CBCT images taken before and after SABG.
Results
TBPs showed differences between IC and MS groups (
P
< 0.05), resulting in greater values of bone volume density (
P
< 0.05) and inferior value of TBPf (
P
= 0.070) in IC group compared with MS group. Using MS+TCP or filling β-TCP granules into donor site significantly improved reconstructed or regenerated BV/TV and Tb.Th (
P
< 0.05) compared with group without β-TCP.
Conclusions
Microstructural characteristics of reconstructed bone bridge were dependent on the donor site of bone harvesting; using an absorbable bone conductive material improved bone quality and increased bone volume density.
Clinical relevance
Application of β-TCP granules as a partial alternative with autologous bone from mandibular symphysis could obtain comparable outcomes in the microstructure of bone bridge to SABG with autologous iliac crest.
•Cobalt/multiwalled carbon nanotube composite films were formed by electrodeposition.•Microstructures of composite films were analyzed.•Cobalt/multiwalled carbon nanotube composite films exhibit ...field emission.
Carbon nanotubes (CNT) are promising for use as field emitters. CNT field emitters in which CNTs are attached to a cathode by a metal are highly suitable structures for CNT field emitters. In this study, Co/CNT composite films were fabricated by composite plating for use as field emitters. Four types of multiwalled CNTs (MWCNTs) with different sizes were used as CNT field emitters. The microstructures, electrical conductivity, and field emission properties of the composite films were evaluated. Co/MWCNT composite films were fabricated with homogeneous distributions of relatively large MWCNTs, whereas small MWCNTs tended to form aggregates in the films. The Co/MWCNT composite films, which had lower electrical conductivities than pure cobalt film, exhibited clear field emission. The Co/MWCNT composite films had field emission electric fields in the range of 1.6–1.9Vμm−1 at an emission current density of 10nAcm−2.
Osteocytes express multiple genes involved in mineral metabolism including PHEX, FGF23, DMP1 and FAM20C. In Hyp mice, a murine model for X-linked hypophosphatemia (XLH), Phex deficiency results in ...the overproduction of FGF23 in osteocytes, which leads to hypophosphatemia and impaired vitamin D metabolism. In this study, to further clarify the abnormality in osteocytes of Hyp mice, we obtained detailed gene expression profiles in osteoblasts and osteocytes isolated from the long bones of 20-week-old Hyp mice and wild-type (WT) control mice. The expression of Fgf23, Dmp1, and Fam20c was higher in osteocytic cells than in osteoblastic cells in both genotypes, and was up-regulated in Hyp cells. Interestingly, the up-regulation of these genes in Hyp bones began before birth. On the other hand, the expression of Slc20a1 encoding the sodium/phosphate (Na+/Pi) co-transporter Pit1 was increased in osteoblasts and osteocytes from adult Hyp mice, but not in Hyp fetal bones. The direct effects of extracellular Pi and 1,25-dihydroxyvitamin D3 1,25(OH)2D3 on isolated osteoblastic and osteocytic cells were also investigated. Twenty-four-hour treatment with 10-8 M 1,25(OH)2D3 increased the expression of Fgf23 in WT osteoblastic cells but not in osteocytic cells. Dmp1 expression in osteocytic cells was increased due to the 24-hour treatment with 10 mM Pi and was suppressed by 10-8 M 1,25(OH)2D3 in WT osteocytic cells. We also found the up-regulation of the genes for FGF1, FGF2, their receptors, and Egr-1 which is a target of FGF signaling, in Hyp osteocytic cells, suggesting the activation of FGF/FGFR signaling. These results implicate the complex gene dysregulation in osteoblasts and osteocytes of Hyp mice, which might contribute to the pathogenesis.
In this paper, out-of-plane bending stiffness of column-end connection between square hollow section column and thick panel with different width was investigated by loading test and finite element ...analysis. From the results, column-end connection of corner-type under 45-degree directional force has the smallest stiffness, and of which section dose not remain plane, and proportion of bending resistance caused by partial deformation of column in column-end bending resistance is very small. Therefore, method to estimate out-of-plane bending stiffness of column-end was proposed based on deformation of diaphragm of hollow section of panel and directly above panel.
Fibroblast growth factor 23 (FGF23), a central regulator of phosphate and vitamin D metabolism, is mainly produced by osteocytes in bone and exerts its effects on distant organs. Despite its ...endocrine function, the mechanism controlling serum FGF23 levels is not fully understood. Here we tested the hypothesis that osteoclastic bone resorption may play a role in regulating circulating levels of FGF23, using a mouse model where injections of interleukin (IL)-1β into the subcutaneous tissue over the calvaria induced rapid bone resorption. A significant amount of FGF23 was detected in the extracts from mouse bones, which supports the idea that FGF23 stays in bone for a while after its production. IL-1β-induced bone resorption was associated with elevated serum FGF23 levels, an effect abolished by pre-treatment with pamidronate.
Fgf23
expression was not increased in either the calvariae or tibiae of IL-1β-injected mice, which suggests that IL-1β facilitated the entry of FGF23 protein into circulation by accelerating bone resorption rather than increasing its gene expression. The direct effect of IL-1β on bone was confirmed when it increased FGF23 levels in the conditioned media of mouse calvariae in organ culture. Repeated treatment of the cultured calvariae with IL-1β led to a refractory phase, where FGF23 was not mobilized by IL-1β anymore. Consistent with the in vivo results, treatment with IL-1β failed to increase
Fgf23
mRNA in isolated primary osteocytes and osteoblasts. These results suggest that FGF23 produced by osteocytes remains in bone, and that rapid bone resorption facilitates its entry into the bloodstream.
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