Multiple proliferation signaling pathways are modulated by octacalcium phosphate in osteoblasts.

Octacalcium phosphate (OCP), a type of bioactive ceramics, may be associated with dentine, tooth apatite, and especially bone generation, and promotes wound healing after fracture. Recently, commercial bone grafting products containing a large amount of OCP material have been released because OCP can be synthesized in large quantities. It is reported to increase cell proliferation, but the interaction between OCP and cell signaling pathways is still unclear. In this study, first, we demonstrated OCP mediated cell signaling pathways with only purified OCP materials. OCP regulated P38, JNK (c-Jun N-terminal kinase), Src, and AKT (protein kinase B) signaling pathways. OCP crystals appeared in the characteristic ribbon shape but varied by several tens of micrometers in size. The X-ray diffraction pattern was the same as previously reported. We studied two concentrations of OCP (10 mg/ml and 20 mg/ml) to understand whether the effect of OCP on cell signaling pathways is dose dependent. We confirmed that OCP treatment affected cell proliferation and alkaline phosphatase and disrupted Src phosphorylation but did not change the total protein level. P38 phosphorylation was activated with OCP treatment and inhibited by SB203580, but P38 total protein level did not change. OCP inhibited JNK phosphorylation signaling, whereas PD98509 inhibited JNK phosphorylation with or without OCP. Interestingly, the AKT total level decreased after OCP treatment, but AKT phosphorylation increased considerably. Our results demonstrate that OCP materials modulate cell signaling pathways and increase cell proliferation.

An Electrochemical Cell for Selective Lithium Capture from Seawater.

Lithium (Li) is a core element of Li-ion batteries (LIBs). Recent developments in mobile electronics such as smartphones and tablet PCs as well as advent of large-scale LIB applications including electrical vehicles and grid-level energy storage systems have led to an increase in demand for LIBs, giving rise to a concern on the availability and market price of Li resources. However, the current Lime-Soda process that is responsible for greater than 80% of worldwide Li resource supply is applicable only in certain regions on earth where the Li concentrations are sufficiently high (salt lakes or salt pans). Moreover, not only is the process time-consuming (12-18 months), but post-treatments are also required for the purification of Li. Here, we have devised a location-independent electrochemical system for Li capture, which can operate within a short time period (a few hours to days). By engaging olivine LiFePO4 active electrode that improves interfacial properties via polydopamine coating, the electrochemical cell achieves 4330 times amplification in Li/Na ion selectivity (Li/Na molar ratio of initial solution = 0.01 and Li/Na molar ratio of final electrode = 43.3). In addition, the electrochemical system engages an I(-)/I3(-) redox couple in the other electrode for balancing of the redox states on both electrode sides and sustainable operations of the entire cell. Based on the electrochemical results, key material and interfacial properties that affect the selectivity in Li capture are identified.

Development of Cellular Signaling Pathways by Bioceramic Heat Treatment (Sintering) in Osteoblast Cells.

Bioceramics are calcium-phosphate-based materials used in medical and dental implants for replacing or repairing damaged bone tissues; however, the effect of bioceramic sintering on the intracellular signaling pathways remains unknown. In order to address this, we analyzed the impact of sintering on the cell signaling pathways of osteoblast cells using sintered and non-sintered hydroxyapatite (HA) and beta-tricalcium phosphate (ß-TCP). X-ray diffraction indicated that only the morphology of HA was affected by sintering; however, the sintered bioceramics were found to have elevated the calcium concentrations in relation to the non-sintered variants. Both bioceramics inhibited the JNK signaling pathway; the sintered HA exhibited half the value of the non-sintered variant, while the sintered ß-TCP rarely expressed a p-JNK value. The total Src and Raptor protein concentrations were unaffected by the sintering, while the p-Src concentrations were decreased. The p-EGFR signaling pathway was regulated by the non-sintered bioceramics, while the p-p38 concentrations were reduced by both the sintered ß-TCP and HA. All of the bioceramics attenuated the total AKT concentrations, particularly the non-sintered HA, and the AKT phosphorylation concentration, except for the non-sintered ß-TCP. Thus, the sintering of bioceramics affects several intracellular signaling pathways. These findings may elucidate the bioceramic function and expand their application scope as novel substrates in clinical applications.

Acceleration of bone formation by octacalcium phosphate composite in a rat tibia critical-sized defect.

Background: The osteogenic capabilities and biodegradability of octacalcium phosphate (OCP) composites make them unique. Despite the excellent characteristics of OCP, their use is limited due to handling difficulties. In this study, we aimed to evaluate and compare three types of OCPs (cemented OCP (C-OCP), C-OCP with collagen (OCP/Col), and synthetic OCP (S-OCP) with alginate (OCP/Alg)) versus commercially available ß-tricalcium phosphate (ß-TCP) regarding their potential to accelerate bone formation in defective rat tibias. Methods: The specimens with OCP composite were manufactured into 5 â€‹mm cubes and inserted into the segmental defects of rat tibias fixed with an external fixator. In addition, 3 â€‹mm-hole defects in rat tibias were evaluated to compare the graft material properties in different clinical situations. Serial X-ray studies were evaluated weekly and the tibias were harvested at postoperative 6 weeks or 8 weeks for radiologic evaluation. Histological and histomorphometric analyses were performed to evaluate the acceleration of bone formation. Results: In the critical-defect model, OCP/Alg showed bone bridges between segmentally resected bone ends that were comparable to those of ß-TCP. However, differences were observed in the residual graft materials. Most ß-TCP was maintained until 8 weeks postoperatively; however, OCP/Alg was more biodegradable. In addition calcification in the ß-TCP occurred at the directly contacted area between graft particles and bony ingrowth was observed in the region adjacent resected surface of tibia. In contrast, no direct bony ingrowth was observed in OCP-based materials, but osteogenesis induced from resected surface of tibia was more active. In the hole-defect model, OCP/Col accelerated bone formation. ß-TCP and OCP/Alg showed similar patterns with relatively higher biodegradability. In histology, among the OCP-based materials, directly contacted new bone was formed only in OCP/Alg group. The new bone formation in the periphery area of graft materials was much more active in the OCP-based materials, and the newly formed bone showed a thicker trabecular and more mature appearance than the ß-TCP group. Conclusions: In this study, OCP/Alg was equivalent to ß-TCP in the acceleration of bone formation with better biodegradability appropriate for clinical situations in different circumstances. Our OCP/Col composite showed fast degradation, which makes it unsuitable for use in mechanical stress conditions in clinical orthopedic settings. The Translational Potential of this Article: In our research, we compared our various manufactured OCP composites to commercially available ß-TCP in critical-defect rat tibia model. OCP/Col showed acceleration in hole-defect model as previous studies in dental field but in our critical-sized defect model it resorbed fast without acceleration of bony union. OCP/Alg showed matched results compared to ß-TCP and relatively fast resorption so we showed market value in special clinical indication depending on treatment strategy. This is the first OCP composite study in orthopaedics with animal critical-sized tibia bone study and further study should be considered for clinical application based on this study.

Effect of water glass coating of tricalcium phosphate granules on in vivo bone formation.

BACKGROUND: Recently, some authors introduced a water glass (WG, sodium-silicate glass; Na2O·SiO2·nH2O) coating over tricalcium phosphate (TCP) bioceramic to modulate its resorption rate and enhance the bone cell behaviors. In this study, four different types of granular samples were prepared to evaluate the ability of new bone formation in vivo using micro-computed tomography and histology. METHODS: Four types sample groups: group A (pure HA as a negative resorption control); group B (pure TCP as a positive resorption control); group C (WG-coated TCP as an early resorption model); and group D (same as group C but heat-treated at 500°C as a delayed resorption model). Cylindrical tube-type carriers with holes were fabricated with HA by extrusion and sintering. Each carrier was filled densely with each granular sample. Four types of tubes were implanted into the medial femoral condyle and medial tibial condyle of New Zealand White rabbits. RESULTS: The HA group (A) showed the lowest amount of new bone formation. All the TCP sample groups (B, C, and D) showed more new bone formation. On the other hand, among the TCP groups, group C (early resorption model) showed slightly more bone formation. The amount of residual bioceramics was most abundant in the HA group (A). All the TCP sample groups showed less residual bioceramics than group A. Among the TCP groups, group C showed slightly more residual bioceramics. Group B showed the lowest amount of residual bioceramics. CONCLUSIONS: The WG-coated TCP sample (group C) is the best bone substitute candidate because of its proper biodegradation rate and the Si ions release because the WG-coated layer reduces the material resorption and enhances the new bone formation. That is, the WG-coated TCP is believed to be the best material for the application of an artificial bone substitute material.

Accuracy of Bolton analysis measured in laser scanned digital models compared with plaster models (gold standard) and cone-beam computer tomography images.

OBJECTIVE: The aim of this study was to compare the accuracy of Bolton analysis obtained from digital models scanned with the Ortho Insight three-dimensional (3D) laser scanner system to those obtained from cone-beam computed tomography (CBCT) images and traditional plaster models. METHODS: CBCT scans and plaster models were obtained from 50 patients. Plaster models were scanned using the Ortho Insight 3D laser scanner; Bolton ratios were calculated with its software. CBCT scans were imported and analyzed using AVIZO software. Plaster models were measured with a digital caliper. Data were analyzed with descriptive statistics and the intraclass correlation coefficient (ICC). RESULTS: Anterior and overall Bolton ratios obtained by the three different modalities exhibited excellent agreement (> 0.970). The mean differences between the scanned digital models and physical models and between the CBCT images and scanned digital models for overall Bolton ratios were 0.41 ± 0.305% and 0.45 ± 0.456%, respectively; for anterior Bolton ratios, 0.59 ± 0.520% and 1.01 ± 0.780%, respectively. ICC results showed that intraexaminer error reliability was generally excellent (> 0.858 for all three diagnostic modalities), with < 1.45% discrepancy in the Bolton analysis. CONCLUSIONS: Laser scanned digital models are highly accurate compared to physical models and CBCT scans for assessing the spatial relationships of dental arches for orthodontic diagnosis.

Accuracy of laser-scanned models compared to plaster models and cone-beam computed tomography.

OBJECTIVE: To compare the accuracy of measurements obtained from the three-dimensional (3D) laser scans to those taken from the cone-beam computed tomography (CBCT) scans and those obtained from plaster models. MATERIALS AND METHODS: Eighteen different measurements, encompassing mesiodistal width of teeth and both maxillary and mandibular arch length and width, were selected using various landmarks. CBCT scans and plaster models were prepared from 60 patients. Plaster models were scanned using the Ortho Insight 3D laser scanner, and the selected landmarks were measured using its software. CBCT scans were imported and analyzed using the Avizo software, and the 26 landmarks corresponding to the selected measurements were located and recorded. The plaster models were also measured using a digital caliper. Descriptive statistics and intraclass correlation coefficient (ICC) were used to analyze the data. RESULTS: The ICC result showed that the values obtained by the three different methods were highly correlated in all measurements, all having correlations>0.808. When checking the differences between values and methods, the largest mean difference found was 0.59 mm±0.38 mm. CONCLUSIONS: In conclusion, plaster models, CBCT models, and laser-scanned models are three different diagnostic records, each with its own advantages and disadvantages. The present results showed that the laser-scanned models are highly accurate to plaster models and CBCT scans. This gives general clinicians an alternative to take into consideration the advantages of laser-scanned models over plaster models and CBCT reconstructions.