Search

Temozolomide (TMZ) is an alkylating agent used for the treatment of aggressive forms of brain tumor based on its antitumor actions. However, the exact effect on cancer and the underlying anticancer molecular mechanism of TMZ remain to be elucidated. In the present study, the effects of TMZ on the growth and motility of glioma C6 cells were investigated. MTT and Transwell assays were used to detect cellular growth and motility. The results showed that TMZ inhibited the proliferation, migration and invasion of the glioma C6 cells in vitro, western blot analysis determined that the phosphorylation of extracellular signal-regulated protein kinase (ERK)1/2 was decreased in the TMZ-treated cells, compared with the untreated control cells. The ERK1/2 specific inhibitor, U0126, augmented the inhibitory effects of TMZ on the proliferation, migration and invasion of the glioma C6 cells, and the mitogen-activated protein kinase kinase/ERK pathway activator, curcumin, attenuated the inhibitory effects of TMZ on the proliferation and motility of the glioma C6 cells. Additionally, the western blotting in the present study demonstrated that TMZ and U0126 decreased the expression of vascular endothelial growth factor-C (VEGF-C), and the expression level was restored by curcumin, suggesting that VEGF-C may be the downstream effector of ERK1/2. Furthermore, the overexpression of VEGF-C enhanced the growth, migration and invasion of the TMZ-treated cells. These results suggested that TMZ suppressed glioma C6 cell development, at least in part, and downregulated the expression of VEGF-C by inhibiting the ERK signaling pathway. The results of the present study provides the foundation for a combinational therapeutic strategy to improve the efficacy of TMZ. [ABSTRACT FROM AUTHOR]

The surface charging behavior as a function of pH and isoelectric points (IEPs) of single-crystal α-Al2O3 (0001) and (1102) and α-Al2O3 (0001) was determined by streaming potential measurements using an electrokinetic analyzer. The IEPs of a-Al2O3 (0001) and (1102) and α-Al2O3 (0001) were found to be 4.5, 5.1, and 6.5, respectively. These IEP values for oriented single crystals of α-Al2O3 are in good agreement with literature values, whereas the new IEP value for α-Al2O3 (0001) is significantly lower than four reported values (IEP = 8-8.5) for single-crystal α-Al2O3 (0001) (Eggleston and Jordan 1998; Zarzycki et al. 2011; Chatman et al. 2013; Lützenkirchen et al. 2013) and significantly higher than one (IEP = 4) recently measured by Lützenkirchen et al. (2015) on a fresh α-Al2O3 (0001) surface. Most of the single-crystal IEP values measured recently are lower than IEP values reported for polycrystalline α-Al2O3 and α-Al2O3, which are generally in the pH range of 8 to 10. Calculations of the IEP values based on estimated Ka values of α-Al2O3 and α-Al2O3surfaces in contact with water as a function of defect type and concentration suggest that highly reactive surface defect sites (primarily singly coordinated aquo groups) on the Fe- and Al-oxide powders are possibly a major source of the surface charge differences between polycrystalline samples and their oriented single-crystal counterparts studied here. The results of this study provide a better understanding of the surface charging behavior of Fe and Al-oxides, which is essential for predicting complex processes such as metal-ion sorption occurring at mineral/water interfaces. [ABSTRACT FROM AUTHOR]

Natural organic matter (NOM) often forms coatings on minerals. Such coatings are expected to affect metal–ion sorption due to abundant sorption sites in NOM and potential modifications to mineral surfaces, but such effects are poorly understood in complex multicomponent systems. Using poly(acrylic acid) (PAA), a simplified analog of NOM containing only carboxylic groups, Pb(II) and Zn(II) partitioning between PAA coatings and α-Al2O3 (1–102) and (0001) surfaces was investigated using long-period X-ray standing wave-florescence yield spectroscopy. In the single-metal–ion systems, PAA was the dominant sink for Pb(II) and Zn(II) for α-Al2O3(1–102) (63% and 69%, respectively, at 0.5 μM metal ions and pH 6.0). In equi-molar mixed-Pb(II)–Zn(II) systems, partitioning of both ions onto α-Al2O3(1–102) decreased compared with the single-metal–ion systems; however, Zn(II) decreased Pb(II) sorption to a greater extent than vice versa, suggesting that Zn(II) outcompeted Pb(II) for α-Al2O3(1–102) sorption sites. In contrast, >99% of both metal ions sorbed to PAA when equi-molar Pb(II) and Zn(II) were added simultaneously to PAA/α-Al2O3(0001). PAA outcompeted both α-Al2O3 surfaces for metal sorption but did not alter their intrinsic order of reactivity. This study suggests that single-metal–ion sorption results cannot be used to predict multimetal–ion sorption at NOM/metal–oxide interfaces when NOM is dominated by carboxylic groups. [ABSTRACT FROM AUTHOR]

The interaction of the l-lactate ion ( l-CH 3CH(OH)COO −, lact −1) with hematite (α-Fe 2O 3) nanoparticles (average diameter 11 nm) in the presence of bulk water at pH 5 and 25 °C was examined using a combination of (1) macroscopic uptake measurements, (2) in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and (3) density functional theory modeling at the B3LYP/6-31+G* level. Uptake measurements indicate that increasing [ lact −1] (aq)results in an increase in lact −1uptake and a concomitant increase in Fe(III) release as a result of the dissolution of the hematite nanoparticles. The ATR-FTIR spectra of aqueous lact −1and lact −1adsorbed onto hematite nanoparticles at coverages ranging from 0.52 to 5.21 µmol/m 2showed significant differences in peak positions and shapes of carboxyl group stretches. On the basis of Gaussian fits of the spectra, we conclude that lact −1is present as both outer-sphere and inner-sphere complexes on the hematite nanoparticles. No significant dependence of the extent of lact −1adsorption on background electrolyte concentration was found, suggesting that the dominant adsorption mode for lact −1is inner sphere under these conditions. On the basis of quantum chemical modeling, we suggest that inner-sphere complexes of lact −1adsorbed on hematite nanoparticles occur dominantly as monodentate, mononuclear complexes with the hydroxyl functional group pointing away from the Fe(III) center. [ABSTRACT FROM AUTHOR]

As one of the fundamental issues in wireless sensor networks (WSNs), the sensor localization problem has recently received extensive attention. In this work, we investigate this problem from a novel perspective by treating it as a functional dual of target tracking. In traditional tracking problems, static location-aware sensors track and predict the position and/or velocity of a moving target. As a dual, we utilize a moving location assistant (LA) (with a global positioning system (GPS) or a predefined moving path) to help location-unaware sensors to accurately discover their positions. We call our proposed system Landscape. In Landscape, an LA (an aircraft, for example) periodically broadcasts its current location (we call it a beacon) while it moves around or through a sensor field. Each sensor collects the location beacons, measures the distance between itself and the LA based on the received signal strength (RSS), and individually calculates their locations via an Unscented Kalman Filter (UKF)-based algorithm. Landscape has several features that are favorable to WSNs, such as high scalability, no intersensor communication overhead, moderate computation cost, robustness to range errors and network connectivity, etc. Extensive simulations demonstrate that Landscape is an efficient sensor positioning scheme for outdoor sensor networks. [ABSTRACT FROM AUTHOR]

Membranes have the potential to substantially reduce energy consumption of industrial chemical separations, but their implementation has been limited owing to a performance upper boundÑthe tradeoff between permeability and selectivity. Although recent developments of highly permeable polymer membranes have advanced the upper bounds for various gas pairs, these polymers typically exhibit limited selectivity. We report a class of hydrocarbon ladder polymers that can achieve both high selectivity and high permeability in membrane separations for many industrially relevant gas mixtures. Additionally, their corresponding films exhibit desirable mechanical and thermal properties. Tuning of the ladder polymer backbone configuration was found to have a profound effect on separation performance and aging behavior. [ABSTRACT FROM AUTHOR]