Ejection of close-in super-Earths around low-mass stars in the giant impact stage

Earth-sized planets were observed in close-in orbits around M dwarfs. While more and more planets are expected to be uncovered around M dwarfs, theories of their formation and dynamical evolution are still in their infancy. We investigate the giant impact growth of protoplanets, which includes strong scattering around low-mass stars. The aim is to clarify whether strong scattering around low-mass stars affects the orbital and mass distributions of the planets. We perform $N$-body simulation of protoplanets by systematically surveying the parameter space of the stellar mass and surface density of protoplanets. We find that protoplanets are often ejected after twice or three times close-scattering around late M dwarfs. The ejection sets the upper limit of the largest planet mass. Adopting the surface density scaling linearly with the stellar mass, we find that as the stellar mass decreases less massive planets are formed in orbits with higher eccentricities and inclinations. Under this scaling, we also find that a few close-in protoplanets are generally ejected. The ejection of protoplanets plays an important role in the mass distribution of super-Earths around late M dwarfs. The mass relation of observed close-in super-Earths and their central star mass is well reproduced by ejection.Comment: accepted for publication in A&

Keishibukuryogan, a Traditional Japanese Medicine, Inhibits Platelet Aggregation in Guinea Pig Whole Blood

Effects of keishibukuryogan (KBG) on platelet aggregation were investigated. To ensure the specificity of KBG, tokishakuyakusan (TSS) and kamisyoyosan (KSS), which are known to have platelet aggregation-inhibiting effects, and rikkunshito (RKT) and shakuyakukanzoto (SKT), which are considered to be devoid of such effects, were used for comparison. The platelet aggregation of each test drug was measured by the screen filtration pressure method using whole blood of guinea pigs and expressed as a collagen-induced pressure rate (%) or a collagen concentration required for 50% increase in the pressure rate (PATI value). KBG suppressed the collagen-induced whole blood pressure rate increase and increased the PATI value, like TSS and KSS. Neither RKT nor SKT showed these effects. The Moutan cortex and Cinnamomi cortex, the constituent crude drugs of KBG, showed KBG-like pressure rate suppression and PATI-increasing effects. Furthermore, paeonol, a representative component of Moutan cortex, and aspirin which is known to have platelet aggregation-inhibiting activity (COX-1 inhibitor) also showed similar effects. These results suggest that the platelet aggregation-inhibiting activity of the constituent crude drugs Moutan cortex and Cinnamomi cortex is involved in the improving effects of KBG on impaired microcirculation and that paeonol plays a role in these effects

Analysis of the Antioxidative Function of the Radioprotective Japanese Traditional (Kampo) Medicine, Hangeshashinto, in an Aqueous Phase

Oral mucositis (OM) is a common and painful complication of radiotherapy for head and neck cancer. Hangeshashinto (HST), a Japanese traditional medicine, is known to alleviate radiotherapy and/or chemotherapy-induced OM; however, the detailed mechanism has not yet been clarified. The aim of the present study is to clarify the details of the antioxidative functions of HST against reactive oxygen species (ROS) produced by radiation. The hydroxyl radical (•OH) scavenging ability and reduction ability was simultaneously measured using a modified electron paramagnetic resonance (EPR) spin trapping method. The superoxide (O2•−) scavenging ability was estimated by an EPR redox probing method. Water suspension of powdered HST and its seven constitutive crude drugs were tested. In addition, some of the main water soluble ingredients of the crude drugs were also tested. HST was found to scavenge both •OH and O2•−. Furthermore, HST was observed to reduce relatively stable nitroxyl radicals. Glycyrrhizae Radix (kanzo), Ginseng Radix (ninjin), Zizyphi Fructus (taiso), and glycyrrhizin (an ingredient of kanzo) were all found to be relatively good •OH scavengers. Scutellariae Radix (ogon) and Coptidis Rhizoma (oren) demonstrated reducing ability. In addition, acteoside and berberine chloride, which are water soluble ingredients of ogon and oren, respectively, also demonstrated reducing ability. Oren exhibited oxidative ability at higher concentrations, which may have a function to maintain catalytic redox action. The antioxidative function of HST probably worked in a balance of scavenging ROS, reducing stable free radicals and some minor oxidative effects

Antinociceptive effect of shakuyakukanzoto, a Kampo medicine, in diabetic mice

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Valproate recovers the inhibitory effect of dexamethasone on the proliferation of the adult dentate gyrus-derived neural precursor cells via GSK-3 beta and beta-catenin pathway

Neurogenesis in the adult dentate gyrus (DC) is decreased in rodent models for mood disorders. Mood stabilizers including lithium (Li) and valproate (VPA) increase it. These increasing effects of Li and VPA on neurogenesis in adult DG are considered to be one of the therapeutic actions of Li and VPA, but their molecular mechanism remains unclear. We have already reported that Li recovers the inhibitory effects of dexamethasone (DEX), an agonist of glucocorticoid receptor, on the proliferation of adult rat DG-derived neural precursor cells (ADP) via GSK-3 beta and beta-catenin pathway. Following it, here we investigated the mechanism underlying the recovery effects of VPA on DEX-induced decrease of ADP proliferation. VPA is an inhibitor of histone deacetylase (HDAC). However, Trichostatin A, a HDAC inhibitor, had no effect on ADP proliferation. In contrast, SB415286, a specific GSK-3 beta inhibitor, recovered DEX-induced decrease of ADP proliferation. In addition, quercetin (Que), a beta-catenin pathway inhibitor, abolished such a recovery effect of VPA. Moreover, nuclear p-catenin and the expression of cyclin D1 were altered by DEX. VPA and Que like the proliferation. Moreover, VPA increased the phosphorylation of Ser(9), which is known as the inhibitory phosphorylation site of GSK-3 beta. These suggest that HDAC is not involved in the recovery effect of VPA on ADP proliferation and that VPA recovers the inhibitory effects of DEX via increasing the phosphorylation of Ser9 on GsK-3 beta and following up-regulation of beta-catenin pathway. Therefore, GSK-3 beta and beta-catenin pathway might play a role in the increasing effects of VPA on neurogenesis on adult DC. (C) 2013 Elsevier B.V. All rights reserved

Yokukansan, a Traditional Japanese Medicine, Enhances the Glutamate Transporter GLT-1 Function in Cultured Rat Cortical Astrocytes

Astrocytes carry two glutamate transporters—GLAST and GLT-1—the latter of which is responsible for >90% of glutamate uptake activity in the brain; however, under culture conditions, the GLT-1 expression in astrocytes is exceedingly low, as is the glutamate uptake activity mediated by GLT-1. This study aimed to elucidate the effects of yokukansan (YKS) in relation to the GLT-1-mediated regulation of extracellular glutamate concentrations. Thus, we treated cultured astrocytes with tumor necrosis factor-α (TNF-α) and dibutyryl-cAMP (dBcAMP) (hereinafter, referred to as “TA”) to increase GLT-1 expression and then functionally examined how YKS would affect glutamate uptake ability derived from GLT-1. Contrary to expectations, although the TA treatments did not affect the uptake activity, YKS significantly augmented it. Conversely, GLAST-derived glutamate uptake was significantly reduced by TA treatments but was unaffected by YKS. Subsequently, we analyzed the GLT-1 protein and mRNA levels and found that TA treatments had significantly increased them, which were then further augmented by YKS. These findings suggest that YKS enhances GLT-1-derived glutamate transport functions in TA-treated cultured astrocytes and that this process entails increased GLT-1 protein and mRNA levels. This type of mechanism may contribute to the YKS-mediated regulation of extracellular glutamate concentrations