Highlights d ASM activity is upregulated in brain and/or plasma of aged humans and mice d Brain endothelial cell is a main contributor of increased ASM in aging d Increased ASM in aging causes BBB impairment and neuronal dysfunction d It is regulated by caveolae-mediated transcytosis and ERM dephosphorylation

Mitogen-activated protein kinases (MAPKs) cascades play important roles in cell proliferation, death, and differentiation in response to external stimuli. However, the precise role of MAPKs in platycodin D (PD)-induced cytotoxicity remains unclear. In this study, we investigated the anticancer effect of PD and its underlying mechanism on AGS human gastric cancer cells. PD significantly inhibited cell proliferation and induced anoikis, which is a form of apoptosis in which cells detach from the substrate. It showed phosphatidylserine externalization, DNA fragmentation, increase of sub-G1 phase, and activation of caspases in a dose- and time-dependent manner. This apoptosis has been associated with the extrinsic pathway via Fas-L and the intrinsic pathway via mitochondrial Bcl-2 family members. Moreover, PD led to the phosphorylation of stresses-activated protein kinases such as JNK and p38, followed by the activation of AP-1. However, pretreatment with SB203580 (a p38 specific inhibitor) suppressed PD-induced p38 and AP-1 activation, and subsequently attenuated the PD-induced apoptosis in AGS cells. These results suggest that p38 activation is responsible for PD-induced apoptosis in AGS cells and PD might be useful for the development as the anticancer agent of gastric cancer.

This Letter reports a fully packaged microelectromechanical system (MEMS) endoscopic catheter for forward imaging optical coherence tomography (OCT). Two-dimensional optical scanning of Lissajous patterns was realized by the orthogonal movement of two commercial aspherical glass lenses laterally mounted on two resonating electrostatic MEMS microstages at low operating voltages. The MEMS lens scanner was integrated on a printed circuit board and packaged with an aluminum housing, a gradient index fiber collimator, and an objective lens. A home-built spectral-domain OCT system with 60 kHz A-line acquisition rate was combined with the endoscopic MEMS catheter. Three-dimensional images of 256×256×995 voxels were directly reconstructed by mapping the A-line datasets along the Lissajous patterns. The endoscopic catheter can provide a new direction for forward endoscopic OCT imaging.

The purpose of this study is to identify relationships of learners’ achievement goal orientation, self-regulation, test-anxiety, self-efficacy, participation, satisfaction, and achievement in online learning environments in Korea. A total of 1,832 student responses from a Korean cyber university were used to find structural relationships of factors. Causal relationships among various variables are provided as results of this study. Achievement goal orientation –approach, self-regulated learning, test-anxiety, and self-efficacy, were positively related to participation; however, achievement goal orientation-avoidance was negatively related to participation. Test-anxiety was directly related to learning achievement and it was found that participation affected learning satisfaction and learning achievement. It was also revealed that learning satisfaction was related to learning achievement. Results of this study suggest that a comprehensive management of learners’ psychological variables, such as achievement goal orientation, self-regulation, test-anxiety, self-efficacy for designing, and managing online learning environments is important to online learning organizations, instructors, and administrators for better learner support.

Platycosides, the saponins found in the roots of Platycodon grandiflorum (Platycodi Radix), are typically composed of oleanane triterpenes with two side chains. In platycosides, platycodin D, a glucose unit at C-3, is a major component, which has several pharmacological activities. Because of the high demand for this compound, we attempted to enzymatically convert platycodin D(3) and platycoside E, having two and three glucose units at C-3, respectively, into platycodin D. In this study, we tested the ability of several glycosidases to transform platycosides, or more specifically, the ability to transform platycoside E and platycodin D(3) into platycodin D. To obtain pure platycodin D on a preparative scale, high-speed countercurrent chromatography with a solvent system of ethyl acetate/n-butanol/water (1.2:1:2, v/v/v) was used for the separation of the enzymatically transformed product. Approximately 39.4 mg of platycodin D (99.8% purity) was obtained from 200 mg of the product in a one-step separation. The results strongly support the advantage of enzymatic transformation of the platycosides for the efficient enrichment of platycodin D in the complicated extract of the medicinal plant.