Novel bioactive adhesive containing dimethylaminohexadecyl methacrylate and calcium phosphate nanoparticles to inhibit metalloproteinases and nanoleakage with three months of aging in artificial saliva.

OBJECTIVES: The objectives of this study were to: (1) develop a multifunctional adhesive via dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP); and (2) investigate its ability to provide metalloproteinases (MMPs) deactivation and remineralization for long-term dentin bonding durability. METHODS: DMAHDM and NACP were incorporated into Adper™ Single Bond 2 Adhesive (SB2) at mass fractions of 5% and 20%, respectively. Degree of conversion and contact angle were measured. Endogenous MMP activity of the demineralized dentin beams, Masson's trichrome staining, nano-indentation, microtensile bond strength and interfacial nanoleakage analyses were investigated after 24 h and 3 months of storage aging in artificial saliva. RESULTS: Adding DMAHDM and NACP did not compromise the degree of conversion and contact angle of SB2 (p > 0.05). DMAHDM and NACP incorporation reduced the endogenous MMP activity by 53 %, facilitated remineralization, and increased the Young's modulus of hybrid layer by 49 % after 3 months of aging in artificial saliva, compared to control. For SB2 Control, the dentin bond strength decreased by 38 %, with greater nanoleakage expression, after 3 months of aging (p < 0.05). However, DMAHDM+NACP group showed no loss in bond strength, with much less nanoleakage, after 3 months of aging (p > 0.05). SIGNIFICANCE: DMAHDM+NACP adhesive greatly reduced MMP-degradation activity in demineralized dentin, induced remineralization at adhesive-dentin interface, and maintained the dentin bond strength after aging, without adversely affecting polymerization and dentin wettability. This new adhesive has great potential to help eliminate secondary caries, prevent hybrid layer degradation, and increase the resin-dentin bond longevity.

The identification of grain size genes by RapMap reveals directional selection during rice domestication.

Cloning quantitative trait locus (QTL) is time consuming and laborious, which hinders the understanding of natural variation and genetic diversity. Here, we introduce RapMap, a method for rapid multi-QTL mapping by employing F2 gradient populations (F2GPs) constructed by minor-phenotypic-difference accessions. The co-segregation standard of the single-locus genetic models ensures simultaneous integration of a three-in-one framework in RapMap i.e. detecting a real QTL, confirming its effect, and obtaining its near-isogenic line-like line (NIL-LL). We demonstrate the feasibility of RapMap by cloning eight rice grain-size genes using 15 F2GPs in three years. These genes explain a total of 75% of grain shape variation. Allele frequency analysis of these genes using a large germplasm collection reveals directional selection of the slender and long grains in indica rice domestication. In addition, major grain-size genes have been strongly selected during rice domestication. We think application of RapMap in crops will accelerate gene discovery and genomic breeding.

Cyclic compression emerged dual effects on the osteogenic and osteoclastic status of LPS-induced inflammatory human periodontal ligament cells according to loading force.

BACKGROUND: Appropriate mechanical stimulation is essential for bone homeostasis in healthy periodontal tissues. While the osteogenesis and osteoclast differentiation of inflammatory periodontal ligament cells under different dynamic loading has not been yet clear. The aim of this study is to clarify the inflammatory, osteogenic and pro-osteoclastic effects of different cyclic stress loading on the inflammatory human periodontal ligament cells (hPDLCs). METHODS: hPDLCs were isolated from healthy premolars and cultured in alpha minimum Eagle's medium (α-MEM). Lipopolysaccharides (LPS) were used to induce the inflammation state of hPDLCs in vitro. Determination of LPS concentration for the model of inflammatory periodontium was based on MTT and genes expression analysis. Then the cyclic stress of 0, 0-50, 0-90 and 0-150 kPa was applied to the inflammatory hPDLCs for 5 days respectively. mRNA and protein levels of osteogenic, osteoclastic and inflammation-related markers were examined after the treatment. RESULTS: MTT and RT-PCR results showed that 10 µg/ml LPS up-regulated TNF-α, IL-1ß, IL-6, IL-8 and MCP-1 mRNA levels (P < 0.05) and did not affect the cell viability (P > 0.05). The excessive loading of stress (150 kPa) with or without LPS strongly increased the expression of inflammatory-related markers TNF-α, IL-1ß, IL-6, IL-8, MCP-1 (P < 0.05) and osteoclastic markers RANKL, M-CSF, PTHLH and CTSK compared with other groups (P < 0.05), but had no significant effect on osteogenic genes. While 0-90 kPa cyclic pressure could up-regulate the expression of osteogenic genes ALP, COL-1, RUNX2, OCN, OPN and OSX in the healthy hPDLSCs. CONCLUSIONS: Collectively, it could be concluded that 0-150 kPa was an excessive stress loading which accelerated both inflammatory and osteoclastic effects, while 0-90 kPa may be a positive factor for the osteogenic differentiation of hPDLCs in vitro.