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PURPOSE: This in-vitro study aimed to evaluate the fracture resistances and failure modes of endodontically treated mandibular premolars restored with endocrowns and conventional post-core retained crowns. MATERIALS AND METHODS: Thirty mandibular premolars were assigned into three groups (n=10): GI, intact teeth; GE, teeth with endocrowns; GC, teeth with conventional post-core supported crowns. Except for the teeth in group GI, all specimens were cut to 1.5 mm above the cementoenamel junction and endodontically treated. Both endocrowns and conventional crowns were fabricated from lithium-disilicate blocks using a CEREC 3D CAD/CAM unit. All specimens were subjected to thermocycling and then to 45° oblique compressive load until fracture occurred. The fracture resistance and failure mode of each specimen were recorded. Data were analyzed with one-way ANOVA and LSD Post Hoc Test (α=.05). RESULTS: The fracture resistances of GE and GC were significantly lower than that of GI (P<.01), while no significant difference was found between GE and GC (P=.702). As of the failure mode, most of the specimens in GE and GC were unfavorable while a higher occurrence of favorable failure mode was presented in GI. CONCLUSION: For the restoration of mandibular premolar, endocrown shows no advantage in fracture resistance when compared with the conventional method. Both of the two methods cannot rehabilitate endodontically treated teeth with the same fracture resistances that intact mandibular premolars have.
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Bicuspid , Crowns , Glass , Lysergic Acid Diethylamide , Methods , Tooth , Tooth CervixABSTRACT
<p><b>OBJECTIVE</b>To explore the effect of ataxia telangiectasia mutated and RAD3 related protein (ATR) expression and ATR kinase activity on the sensitivity to cisplatin in ovarian cancer SKOV3 cells.</p><p><b>METHODS</b>SiRNA targeting ATR was transfected into SKOV3 cells for 48 h to reduce the ATR protein level, and ATR kinase inhibitor VE-821 was used for 12 h to inhibit the ATR pathway activity. The alteration of cell viability was examined by CCk-8 assay. Expression levels of ATR, p-ATR and γ-H2AX proteins were detected by Western blot. The DNA double strand breaks (DSB) marker γ-H2AX and homologous recombination repair key protein RAD51 and their co-localization in the cells were examined under the confocal microscope. The status of DNA double strand breaks (DSB) in single cells was visualized by alkaline comet assay. Finally, the cell cycle distribution was assessed using flow cytometry.</p><p><b>RESULTS</b>DDP caused evident DNA double strands breaks and activated ATR kinase pathway. ATR-siRNA notably reduced ATR protein level, the 48 h IC(50) value of DDP was 72.12 µmol/L and 41.25 µmol/L, respectively, in the NC-siRNA and ATR-siRNA groups (P < 0.05). Confocal microscopic assay presented decreased recruitment of RAD51 at the DSB loci and comet assay showed enhanced DSB in the cells after ATR knocking down. After the inhibition of ATR kinase by VE-821, the 48 h IC(50) value of DDP was 75.32 µmol/L and 45.64 µmol/L, respectively, in the DMSO and VE-821 groups (P < 0.05 for both), confocal microscopic assay demonstrated reduced RAD51 recruitment, and comet assay showed increased DSB in cells after ATR kinase inhibition. Flow cytometry showed that percentage of cells distributed in G(0)/G(1), S and G(2)/M phases was 71.2%, 13.4% and 15.4%, repectively, after 40 µmol/L DDP treatment for 24 h. Compared with that of control group (G(0)/G(1): 54.2%, S: 21.3% and G(2)/M: 24.4%), DDP induced G(0)/G(1) phase arrest. DDP intervention resulted in the cell cycle status (G(0)/G(1): 43.2%, S: 20.4%, G(2)/M: 36.4%) in the ATR-siRNA group and (G(0)/G(1): 40.2%, S: 22.5%, G(2)/M: 37.3%) in the VE-821 group, indicating that the inhibition of ATR or ATR kinase could abrogate the effect of G(0)/G(1) phase arrest induced by DDP.</p><p><b>CONCLUSIONS</b>Suppression of ATR can affect the homologous recombination repair in ovarian cancer cells, leading to accumulation of DNA double strand breaks in the cell nuclei as well as reduction of DDP-caused G(0)/G(1) phase arrest, finally enhances the sensitivity to cisplatin in the ovarian cancer SKOV3 cells.</p>
Subject(s)
Female , Humans , Antineoplastic Agents , Pharmacology , Cell Cycle , Cell Line, Tumor , Cisplatin , Pharmacology , DNA Repair , Ovarian Neoplasms , Pyrazines , RNA, Small Interfering , Sulfones , TransfectionABSTRACT
Chemotherapy is the preferred therapeutic approach for advanced ovarian cancer, but a successful long-term treatment is prevented by the development of drug resistance. Recent works have underlined the involvement of non-coding RNAs, microRNAs (miRNAs) in cancer development, with several conjectures regarding their possible involvement in the evolution of drug resistance. This study is to investigate the promoting effects and mechanism of miR-125b involved in the development of chemoresistance in ovarian cancer. The different expression of miR-125b in cisplatin-sensitive ovarian cancer cell line (OV2008) and its resistant variant (C13*) was identified by real-time PCR. An in vitro cytotoxicity assay and apoptosis assay using CCK-8 assay and flow cytometry, were carried out to detect the effect of miR-125b and Bak1 on cisplatin resistance of cells. Real-time PCR, Western blotting and luciferase reporter assay were used to detect whether Bak1 is a target of miR-125b. As compared with OV2008 cells, the expression levels of miR-125b in C13* cells were increased. It was found that the up-regulation of microRNA-125b caused a marked inhibition of cisplatin-induced cytotoxicity and apoptosis and a subsequent increase in the resistance to cisplatin in OV2008 and C13* cells. Moreover, Bak1 was a direct target of miR-125b, and down-regulation of Bak1 suppressed cisplatin-induced apoptosis and led to an increased resistance to cisplatin. Our study indicates that miR-125b has a significantly promoting effect on chemoresistance of C13* cells and up-regulation of miR-125b expression contributes to cisplatin resistance through suppression of Bak1 expression. This finding has important implications in the development of targeted therapeutics for overcoming cisplatin resistance in ovarian cancer.
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The current mental health of college students can not be optimistic.This paper summarized college students' psychological crisis from the perspectives of psychological crisis and crisis intervention,came up with updated research outcomes and deficiencies,and pointed out the direction of its future research and development.
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OBJECTIVE:To explore the effect of dimethylsulfoxid(DMSO)on the activity and function of platelet in vit?ro.METHODS:Fresh random-donor platelet unit(n=60)were divided into3equal groups.A DMSO-free group was chosen as a control group.The other two groups included a washed platelet group and a DMSO group to which DMSO was added with a final concentration of3%.All the groups were stored on a horizontal shaker at room temperature.Changes of adherence rate,aggregating function and recovery rate from hypotonic shack of platelet were observed.RESULTS:In the DMSO group,platelet adherence rate,aggregating function,and recovery rate from hypotonic shack decreased during storage comparing with control and washed platelet groups.CONCLUSION:DMSO has a protective effect on platelet and its action is reversible.
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Objective To investigate the early effect of medium-dose ionic irradiation on the expression of Fos protein in the rat brain. Methods Fos protein was observed in rat brains at times ranging from 24 hours to 4 weeks after hemispheric irradiation (single-fraction maximal dose of 20Gy) with the immunohistochemical technique. Results Compared with that of the un-radiated rats,the expression of Fos protein in the irradiated brain decreased distinctly 24 hours and 1 week after irradiation.However,the quantity of Fos immunopositive cells increased gradually afterwards.At four weeks after radiation,expression of Fos protein recovered progressively in medulla oblongata and pons,in which Fos immunopositive cells were more than those in control group.In contrast,expression level of Fos protein in mesencephalon,diencephalons or telencephalon was still less compared with that of the un-irradiated rats.Conclusion The result suggested that the neuronal activity might be inhibited in certain nuclei of the rat brain in early stages after hemisphere irradiation,and this inhibitory phenomenon was more obviously in higher neural centers.