Wear and Corrosion Properties of Pure Mo Coating Layer Manufactured by Atmospheric Plasma Spray Process

A pure molybdenum (Mo) coating layer was manufactured by using the atmospheric plasma spray (APS) process and its wear and corrosion characteristics were investigated in this study. A Mo coating layer was prepared to a thickness of approximately 480 μm, and it had sound physical properties with a porosity of 2.9% and hardness of 434 Hv. Room temperature dry wear characteristics were measured through a ball-on-disk test under load conditions of 5 N, 10 N and 15 N. Based on the coefficient of friction graph at 5 N and 10 N, the oxides formed during wear functioned as a wear lubricant, thereby confirming an increase in wear resistance. However, at 15 N, wear behavior changed, and wear occurred due to splat pulling out. A potentiodynamic polarization test was conducted under an artificial seawater atmosphere, and Ecorr and Icorr measured 0.717 V and 7.2E-5 A/cm2, respectively. Corrosion mainly occurred at the splat boundary and pores that were present in the initial state. Based on the findings above, the potential application of APS Mo coating material was also discussed

Salinomycin enhances doxorubicin-induced cytotoxicity in multidrug resistant MCF-7/MDR human breast cancer cells via decreased efflux of doxorubicin

Salinomycin is a monocarboxylic polyether antibiotic, which is widely used as an anticoccidial agent. The anticancer property of salinomycin has been recognized and is based on its ability to induce apoptosis in human multidrug resistance (MDR). The present study investigated whether salinomycin reverses MDR towards chemotherapeutic agents in doxorubicin-resistant MCF-7/MDR human breast cancer cells. The results demonstrated that doxorubicin-mediated cytotoxicity was significantly enhanced by salinomycin in the MCF-7/MDR cells, and this occurred in a dose-dependent manner. This finding was consistent with subsequent observations made under a confocal microscope, in which the doxorubicin fluorescence signals of the salinomycin-treated cells were higher compared with the cells treated with doxorubicin alone. In addition, flow cytometric analysis revealed that salinomycin significantly increased the net cellular uptake and decreased the efflux of doxorubicin. The expression levels of MDR-1 and MRP-1 were not altered at either the mRNA or protein levels in the cells treated with salinomycin. These results indicated that salinomycin was mediated by its ability to increase the uptake and decrease the efflux of doxorubicin in MCF-7/MDR cells. Salinomycin reversed the resistance of doxorubicin, suggesting that chemotherapy in combination with salinomycin may benefit MDR cancer therapyopen

Stemness Evaluation of Mesenchymal Stem Cells from Placentas According to Developmental Stage: Comparison to Those from Adult Bone Marrow

This study was done to evaluate the stemness of human mesenchymal stem cells (hMSCs) derived from placenta according to the development stage and to compare the results to those from adult bone marrow (BM). Based on the source of hMSCs, three groups were defined: group I included term placentas, group II included first-trimester placentas, and group III included adult BM samples. The stemness was evaluated by the proliferation capacity, immunophenotypic expression, mesoderm differentiation, expression of pluripotency markers including telomerase activity. The cumulative population doubling, indicating the proliferation capacity, was significantly higher in group II (P<0.001, 31.7±5.8 vs. 15.7±6.2 with group I, 9.2±4.9 with group III). The pattern of immunophenotypic expression and mesoderm differentiation into adipocytes and osteocytes were similar in all three groups. The expression of pluripotency markers including ALP, SSEA-4, TRA-1-60, TRA-1-81, Oct-4, and telomerase were strongly positive in group II, but very faint positive in the other groups. In conclusions, hMSCs from placentas have different characteristics according to their developmental stage and express mesenchymal stemness potentials similar to those from adult human BMs

Inhibition of autophagy promotes salinomycin-induced apoptosis via reactive oxygen species-mediated PI3K/AKT/mTOR and ERK/p38 MAPK-dependent signaling in human prostate cancer cells

Recently, the interplay between autophagy and apoptosis has become an important factor in chemotherapy for cancer treatment. Inhibition of autophagy may be an effective strategy to improve the treatment of chemo-resistant cancer by consistent exposure to chemotherapeutic drugs. However, no reports have clearly elucidated the underlying mechanisms. Therefore, in this study, we assessed whether salinomycin, a promising anticancer drug, induces apoptosis and elucidated potential antitumor mechanisms in chemo-resistant prostate cancer cells. Cell viability assay, Western blot, annexin V/propidium iodide assay, acridine orange (AO) staining, caspase-3 activity assay, reactive oxygen species (ROS) production, and mitochondrial membrane potential were assayed. Our data showed that salinomycin alters the sensitivity of prostate cancer cells to autophagy. Pretreatment with 3-methyladenine (3-MA), an autophagy inhibitor, enhanced the salinomycin-induced apoptosis. Notably, salinomycin decreased phosphorylated of AKT and phosphorylated mammalian target of rapamycin (mTOR) in prostate cancer cells. Pretreatment with LY294002, an autophagy and PI3K inhibitor, enhanced the salinomycin-induced apoptosis by decreasing the AKT and mTOR activities and suppressing autophagy. However, pretreatment with PD98059 and SB203580, an extracellular signal-regulated kinases (ERK), and p38 inhibitors, suppressed the salinomycin-induced autophagy by reversing the upregulation of ERK and p38. In addition, pretreatment with N-acetyl-L-cysteine (NAC), an antioxidant, inhibited salinomycin-induced autophagy by suppressing ROS production. Our results suggested that salinomycin induces apoptosis, which was related to ROS-mediated autophagy through regulation of the PI3K/AKT/mTOR and ERK/p38 MAPK signaling pathways

Pregnancy outcomes in twin pregnancies over 10 years

Objective The aim of this study was to evaluate the changes in twin pregnancy outcomes between 2007 and 2016 in a Korean population. Methods The data for this nationwide population-based study was obtained from the national birth registry of the Korean National Statistical Office and the Health Insurance Review & Assessment Service of Korea. Women with twin pregnancies who gave birth between 2007 and 2016 were included. Results From 2007 to 2016, the rate of twin pregnancies increased (1.37% vs. 1.91%, respectively, P<0.0001). The risk of preterm birth (adjusted odds ratio [aOR], 1.77; 95% confidence interval [CI], 1.66–1.89) also increased; however, the risk of twin growth discordance (aOR, 0.90; 95% CI, 0.82–0.99) decreased. The risks of cesarean section (aOR, 1.16; 95% CI, 1.03–1.29), gestational diabetes mellitus (aOR, 2.10; 95% CI, 1.83–2.39), and postpartum hemorrhage (aOR, 1.27; 95% CI, 1.14–1.41) all increased from 2007 to 2016. Conclusion Twin pregnancy outcomes have changed significantly in Korea over a recent 10-year period

Enhancement of paclitaxel-induced breast cancer cell death via the glycogen synthase kinase-3 beta-mediated B-cell lymphoma 2 regulation

Glycogen synthase kinase-3 beta (GSK-3 beta) is a serine/threonine protein kinase that is known to mediate cancer cell death. Here, we show that B-cell lymphoma 2 (Bcl-2), an anti-apoptotic protein, is regulated by GSK-3 beta and that GSK-3 beta-mediated regulation of Bcl-2 is crucial for mitochondrial-dependent cell death in paclitaxel-stimulated cells. We demonstrate that MCF7 GSK3 beta siRNA cells are more sensitive to cell death than MCF7 GFP control cells and that in the absence of GSK-3 beta, Bcl-2 levels are reduced, a result enhanced by paclitaxel. Paclitaxel-induced JNK (c-Jun N-terminal kinase) activation is critical for Bcl-2 modulation. In the absence of GSK-3 beta, Bcl-2 was unstable in an ubiquitination-dependent manner in both basal-and paclitaxel-treated cells. Furthermore, we demonstrate that GSK-3 beta-mediated regulation of Bcl-2 influences cytochrome C release and mitochondrial membrane potential. Taken together, our data suggest that GSK-3 beta-dependent regulation of Bcl-2 is crucial for mitochondria-dependent cell death in paclitaxel-mediated breast cancer therapy.clos