Zirconates with high melting points were investigated for application as materials for thermal barrier coatings at operating temperatures >1300°C. SrZrO 3 , BaZrO 3 , and La 2 Zr 2 O 7 powders were synthesized and sintered to compacts with various levels of porosity. The sintering results indicated a promising low-sintering activity of the investigated materials. Thermal properties of these dense materials were determined. Thermal expansion coefficients were slightly lower than those of Y 2 O 3 -stabilized ZrO 2 (YSZ); thermal conductivities of SrZrO 3 and BaZrO 3 were comparable or slightly higher than those of YSZ. La 2 Zr 2 O 7 had a lower thermal conductivity. SrZrO 3 was not suitable for application as a thermal barrier coating because of a phase transition at temperatures between 700°and 800°C. Mechanical properties (hardness, fracture toughness, and Young's modulus) of dense BaZrO 3 and La 2 Zr 2 O 7 samples were determined by indentation techniques and showed lower hardness and Young's modulus compared to YSZ. BaZrO 3 and La 2 Zr 2 O 7 powders were optimized for application as powders for plasma spraying. Plasma-sprayed coatings were produced and characterized. Thermal cycling with a gas burner at 1200°C showed a massive attack of the BaZrO 3 coating, with loss of BaO. On the other hand, the La 2 Zr 2 O 7 coating showed excellent thermal stability and thermal shock behavior.

Aim: To investigate the therapeutic effects of resveratrol (RSV) on periodontitis in diabetic mice and to explore the underlying mechanisms in vitro. Methods: Experimental periodontitis was induced in db/db mice by ligature application of porphyromonas gingivalis. The mice were treated with RSV (20 mg/kg, po) daily for 4 weeks. Alveolar bone loss, proinflammatory cytokines and TLR4 expression in the gingival tissue were measured. Cultured gingival epithelial cells (GECs) were used for in vitro studies. The transcriptional activity of TLR4 downstream signaling was analyzed using Western blotting. Results: RSV administration significantly decreased the blood glucose levels, and ameliorated alveolar bone loss in db/db mice with experimental periodontitis. RSV administration also suppressed the high levels of IL-1β, IL-6, IL-8, TNF-α, and TLR4 in gingival tissue of the mice. In the GECs incubated in high glucose medium, TLR4 expression was substantially upregulated, which was partly blocked in the presence of RSV. Lipopolysaccharides markedly increased the expression and secretion of IL-1β, IL-6, IL-8, and TNF-α in the GECs cultured in high glucose medium, which was also partly blocked in the presence of RSV. Furthermore, RSV significantly suppressed the phosphorylation of TLR4 downstream factors NF-κB p65, p38MAPK, and STAT3. Conclusion: RSV exerts protective effects against experimental periodontitis in db/db mice via negative regulation of TLR4 signaling.

Adiponectin (APN) is an adipocyte-secreted adipokine that exerts well-characterized anti-diabetic properties. Patients with type 2 diabetes (T2D) are characterized by reduced APN levels in circulation and impaired stem cell and progenitor cell mobilization from the bone marrow for tissue repair and remodeling. In this study, we found that APN regulates the mobilization and recruitment of bone marrow-derived mesenchymal stem cells (BMSCs) to participate in tissue repair and regeneration. APN facilitated BMSCs migrating from the bone marrow into the circulation to regenerate bone by regulating stromal cell-derived factor (SDF)-1 in a mouse bone defect model. More importantly, we found that systemic APN infusion ameliorated diabetic mobilopathy of BMSCs, lowered glucose concentration and promoted bone regeneration in diet-induced obesity (DIO) mice. In vitro studies allowed us to identify Smad1/5/8 as a novel signaling mediator of APN receptor (AdipoR)-1 in BMSCs and osteoblasts. APN stimulation of MC3T3-E1 osteoblastic cells led to Smad1/5/8 phosphorylation and nuclear localization and increased SDF-1 mRNA expression. Although APN-mediated phosphorylation of Smad1/5/8 occurred independently from adaptor protein, phosphotyrosine interaction, pleckstrin homology domain and leucine zipper containing 1 (APPL1), it correlated with the disassembly of protein kinase casein kinase II (CK2) and AdipoR1 in immunoprecipitation experiments. Taken together, this study identified APN as a regulator of BMSCs migration in response to bone injury. Therefore, our findings suggest APN signaling could be a potential therapeutic target to improve bone regeneration and homeostasis, especially in obese and T2D patients.

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