Alizarin

A sensor for the adsorptive stripping voltammetric determination of rare earth elements has been developed. The electrochemical procedure is based on the oxidation of the rare earth elements complexed with alizarin complexone at a glassy carbon electrode that was in situ modified with an antimony film, during an anodic scan from -0.2 V to 1.1 V (vs. Ag/AgCl) and deposition potential of -0.1 V (vs. Ag/AgCl). The factors influencing the adsorptive stripping capability were optimised, including the complexing agent concentration, plating concentration of antimony and deposition time. The detection of rare earth elements (La, Ce and Pr) were realised in 0.08 M sodium acetate (pH = 5.8) solution as supporting electrolyte, with 2 × 10-6 M alizarin complexone and 1.0 mg L-1 antimony solution. Under the optimised conditions, a deposition time of 360 s was obtained and a linear response was observed between 1 and 25 µg L-1. The reproducibility of the voltammetric measurements was found to be within 5.

Calcium hydroxide and mineral trioxide aggregate are widely used for indirect and direct pulp capping and root canal filling. Their dissociation into Ca2+and OH-in dental pulp creates an alkaline environment, which activates reparative/reactionary dentinogenesis. However, the mechanisms by which odontoblasts detect the pH of the extracellular environment remain unclear. We examined the alkali-sensitive intracellular Ca2+signaling pathway in rat odontoblasts. In the presence or absence of extracellular Ca2+, application of alkaline solution increased intracellular Ca2+concentration, or [Ca2+]i Alkaline solution-induced [Ca2+]iincreases depended on extracellular pH (8.5 to 10.5) in both the absence and the presence of extracellular Ca2+ The amplitude was smaller in the absence than in the presence of extracellular Ca2+ Each increase in [Ca2+]i, activated by pH 7.5, 8.5, or 9.5, depended on extracellular Ca2+concentration; the equilibrium binding constant for extracellular Ca2+concentration decreased as extracellular pH increased (1.

Naringin is a major flavonoid found in grapefruit and is an active compound extracted from the Chinese herbal medicine Rhizoma Drynariae. Naringin is a potent stimulator of osteogenic differentiation and has potential application in preventing bone loss. However, the signaling pathway underlying its osteogenic effect remains unclear. We hypothesized that the osteogenic activity of naringin involves the Notch signaling pathway. Rat bone marrow stromal cells (BMSCs) were cultured in osteogenic medium containing-naringin, with or without DAPT (an inhibitor of Notch signaling), the effects on ALP activity, calcium deposits, osteogenic genes (ALP, BSP, and cbfa1), adipogenic maker gene PPARγ2 levels, and Notch expression were examined. We found that naringin dose-dependently increased ALP activity and Alizarin red S staining, and treatment at the optimal concentration (50 μg/mL) increased mRNA levels of osteogenic genes and Notch1 expression, while decreasing PPARγ2 mRNA levels.

OBJECTIVES: Dental mesenchymal stem cells (MSCs) are easily obtained; however, mechanisms underlying directed differentiation of these cells remains unclear. Wnt/β-catenin signalling is essential for mesenchymal cell commitment and differentiation, and Wnt inhibition is linked to stem cell maintenance and function. Secreted frizzled-related protein 2 (SFRP2) competes with the Frizzled receptor for direct binding to Wnt and blocks activation of Wnt signalling. Here, we used stem cells derived from apical papillae (SCAPs) to study the functions of SFRP2.