Evaluation of microtensile bond strength between resin composite and glass ceramic / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the microtensile bond strength of resin composite to glass ceramic, and the effect of surface treatment of resin composite and thermal cycling aging on the microtensile bond strength.@*METHODS@#Rectangular blocks were made with dentin of extracted molars, resin composite or feldspathic glass ceramic respectively. The bonding surfaces of these rectangular blocks were sanded by 600-grit silicon carbide paper before luting. A self-etching resin cement was used as luting agent. The specimens were divided into groups according to the types of substrates of adhesion (dentin/glass ceramic or resin composite/glass ceramic), the way of surface treatments and whether thermal cycling aging ocurred. The dentin blocks were adhered to ceramic blocks as controls (group A1 and A2). The resin composite blocks were adhered to the ceramic blocks as experiment groups. The resin composite surfaces were treated by different ways before luting: no extra surface treatment (group B1 and B2), treated by ethyl methacrylate solution (group C1 and C2) or silane coupling agent (group D1 and D2), coarsened by 360-grit silicon carbide paper (group E1 and E2) or polished by 1 200-grit silicon carbide paper (group F1 and F2). After luting, the microtensile bond strength of the specimens were tested before (group A1-F1) or after (group A2-F2) thermal cycling aging. After microtensile bond strength test, the fracture bonding surfaces of the specimens were observed by a scanning electron microscopy to determine the type of bonding failure. The data were statistically analyzed using one-way analysis of variance.@*RESULTS@#The microtensile bond strength of resin composite to glass ceramic with no extra treatment achieved high bond values before and after thermal cycling [B1 (30.02±3.85) MPa, B2 (26.83±3.14) MPa], which were statistically different from those of the control groups [A1 (20.55±4.51) MPa, A2 (12.94±0.69) MPa, P < 0.05]. The microtensile bond strength between the glass ceramic and resin composite did not increase after different surface treatments of resin composite.@*CONCLUSIONS@#The microtensile bond strength between resin composite and glass ceramic achieved as similar bond strength as that between dentin and glass ceramic and even better. Surface treatment of resin composite via methyl methacrylate solution, silane coupling agent, coarsening, or polishing did not increase the microtensile bond strength effectually.

Research progress of bioactivity of steroidal saponins in recent ten years / 中国中药杂志

Steroidal saponins have a wide range of pharmacological effects and biological activities, such as anti-tumor, antifungal, hypoglycemic, immune regulation, insecticides, etc. In the last ten years, some new structures of steroidal saponins compounds were found from natural plants, they have some new and different activities. In order to accelerate the research on the drug innovation of steroidal saponins, we summarized the new progress of the research on such compounds.

γ-Secretase Inhibitor, DAPT Inhibits Self-renewal and Stemness Maintenance of Ovarian Cancer Stem-like Cells In Vitro.

OBJECTIVE: The Notch signaling pathway plays an important role in the stem cell signaling network and contributes to tumorigenesis. However, the functions of Notch signaling in ovarian cancer stem cells (OCSCs) are not well understood. We aimed to investigate the effects of Notch blockade on self-renewal and stemness maintenance of OCSCs. METHODS: Ovarian cancer stem-like cells were enriched from ovarian cancer cell lines in serum-free medium. A γ-secretase inhibitor, (DAPT), was used to block Notch signaling. MTT assays were performed to assess self-renewal and proliferation inhibition, flow cytometry was performed to analyze cell surface marker and immunofluorescence, Western Blot and Real-time RT-PCR assays were performed to detect Oct4 and Sox2 protein and mRNA expression of the Ovarian cancer stem-like cells treated with DAPT. RESULTS: Notch blockade markedly inhibits self-renewal and proliferation of ovarian cancer stem-like cells, significantly downregulates the expression of OCSCs-specific surface markers, and reduces protein and mRNA expression of Oct4 and Sox2 in OCSC-like cells. CONCLUSION: Our results suggest that Notch signaling is not only critical for the self-renewal and proliferation of OCSCs, but also for the stemness maintenance of OCSCs. The γ-secretase inhibitor is a promising treatment targeting OCSCs.

Paclitaxel-doxorubicin sequence is more effective in breast cancer cells with heat shock protein 27 overexpression.

BACKGROUND: Cancer cells with overexpression of heat shock protein 27 (HSP27) are resistant to chemotherapeutic drug doxorubicin (Dox). Paclitaxel (Pacl) was reported to suppress HSP27 expression in ovarian and uterine cancer cells. The purposes of this study were to investigate whether Pacl inhibits the expression of HSP27 in breast cancer cells, whether Pacl can sensitize breast cancer cells with HSP27 overexpression to Dox, and to define a more effective schedule for the combination of Dox with Pacl. METHODS: The HSP27 high-expressing human breast cancer cell lines, MCF-7 and MDA-MB-435, and the HSP27 low-expressing cell line, MDA-MB-231, were used in this study. The level of HSP27, topoisomerase (Topo) IIalpha and beta expression were assessed by Western blotting. The cytotoxic activities of Dox, Pacl and combination of these two drugs were evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay and flow cytometric assays. RESULTS: Pacl (0.1 micromol/L) inhibited HSP27 expression by approximately 2-fold in MCF-7 and MDA-MB-435 cells, while up-regulating the level of topo IIalpha and beta. In contrast, expression of HSP27 in MDA-MB-231 did not change significantly following Pacl treatment. There were synergistic effects in both treatment sequences (Pacl-Dox and Dox-Pacl) when Pacl was combined with Dox. Compared with those treated with the Dox-Pacl sequence, the Pacl-Dox sequence had a stronger effect in cancer cells with HSP27 overexpression, as MCF-7 and MDA-MB-435 treated with the Pacl-Dox sequence had lower viabilities and a higher apoptotic rate. CONCLUSIONS: Paclitaxel significantly decreases the level of HSP27 in breast cancer cells overexpressing HSP27. In combination therapies, the Pacl-Dox sequence is more effective in clearing breast cancer cells with high HSP27 expression compared with the Dox-Pacl sequence.

Microwave-assisted regeneration of hypercrosslinked polymeric adsorbent saturated with nitrophenols.

Thermal regeneration of hypercrosslinked polymeric adsorbent (HPA) was performed at 67 degrees C. Experiments were carried out using a multimode microwave oven operating at 2450 MHz and a thermostatic water bath so as to compare the effect of the different heating mechanisms on the regeneration efficiency of the HPA saturated with nitrophenols. The temperature rise action of the heterogeneous regeneration system under microwave irradiation was described. Additionally, a complete structure and chemical characterization of the regenerated HPA was also carried out in order to study the influence of the subsequent regeneration cycles on the structure and the adsorption capacities of the adsorbents. Structure characterization of the regenerated HPA was accomplished by means of the analysis of FTIR spectra.