High-density and low-roughness anodic oxide formed on SiC in highly concentrated LiCl aqueous solution

The wide bandgap and high carrier mobility of silicon carbide (SiC), as well as its physical and chemical stability, make it a promising material for a number of applications. One of the key requirements for these applications involves oxide formation on SiC. The usefulness of the oxide produced by anodizing is, however, limited since the anodic oxide formed on SiC in the usual dilute aqueous solution has a low density and high surface roughness. Here, we consider a new parameter in anodic oxide formation by focusing on the concentration of free water in the electrolyte, using a highly concentrated aqueous solution. In a concentrated solution, oxygen evolution, which results in a reduction in the density of the oxide, is suppressed, and the rate of formation of anodic oxide at defect sites effectively decreases to reduce the surface roughness. Furthermore, an interfacial layer with a higher density than SiO₂ is formed between SiC and SiO₂, buffering the difference in density between them. As a result, we successfully obtained an anodic oxide with a relatively high density and low surface roughness. This study provides a new approach to improving the properties of the anodic oxide formed on SiC

Using Xenopus tissue cultures for the study of myasthenia gravis pathogenesis

© 2015 Elsevier Inc. Myasthenia gravis (MG), the most common autoimmune disease of neuromuscular junction (NMJ), is heterogeneous in terms of pathophysiology, which is determined by the pathogenic antigen of autoantibodies targeting to synaptic proteins at the NMJs. Currently, patients suspected with MG are routinely screened for the presence of autoantibodies against acetylcholine receptor (AChR) or muscle-specific kinase (MuSK) using a cell-based assay (CBA) that involves the expression of target synaptic membrane protein in heterologous cell lines. However, some autoantibodies may only show reactivity for binding to densely clustered AChR in the physiological conformation, while AChR clustering is known to involve signaling events orchestrated by over a dozen of postsynaptic proteins. To improve the existing serological diagnosis of MG, this study explored the possibility of using the well-established Xenopus primary culture system as a novel CBA for MG. Here, by examining the pathogenic effects of four MG human plasma samples, we found that the samples from both seropositive and seronegative MG patients effectively induced the disassembly of aneural AChR clusters in cultured Xenopus muscle cells, as well as the nerve-induced AChR clusters in the nerve-muscle co-cultures. Importantly, the disassembly of AChR clusters was spatio-temporally correlated to the disappearance of actin depolymerizing factor (ADF)/cofilin, an actin regulator involved in AChR trafficking and clustering. Taken together, this study develops a reliable CBA using Xenopus primary cultures for screening the pathogenicity of human MG plasma samples, and providing a platform for investigating the pathogenic mechanisms underlying the endocytic trafficking and degradation of AChRs at NMJs in MG patients.published_or_final_versio

Regulation of Cytochrome b5 Expression by miR-223 in Human Liver: Effects on Cytochrome P450 Activities

Purpose: Cytochrome b 5 (b 5) is a hemoprotein that transfers electrons to several enzymes to fulfill functions in fatty acid desaturation, methemoglobin reduction, steroidogenesis, and drug metabolism. Despite the importance of b 5, the regulation of b 5 expression in human liver remains largely unknown. We investigated whether microRNA (miRNA) might be involved in the regulation of human b 5. Methods: Twenty-four human liver specimens were used for correlation analysis. In silico analysis and luciferase assay were performed to determine whether the predicted miRNAs functionally target to b 5. The miR-223 was overexpressed into HepG2 cells infected with adenovirus expressing human cytochrome P450. Results: In human livers, the b 5 protein levels were not positively correlated with the b 5 mRNA levels, and miR-223 levels were inversely correlated with the b 5 mRNA levels or the translational efficiencies. The luciferase assay showed that miR-223 functionally binds to the element in the 3′-untranslated region of b 5 mRNA. The overexpression of miR-223 significantly reduced the endogenous b 5 protein level and the mRNA stability in HepG2 cells. Moreover, the overexpression of miR-223 significantly reduced CYP3A4-catalyzed testosterone 6β-hydroxylation activity and CYP2E1-catalyzed chlorzoxazone 6-hydroxylase activity but not CYP1A2-catalyzed 7-ethoxyresorufin O-deethylase activity. Conclusions: miR-223 down-regulates b 5 expression in the human liver, modulating P450 activities. © 2013 Springer Science+Business Media New York

Common mechanism for helical nanotube formation by anodic polymerization and by cathodic deposition using helical pores on silicon electrodes

We report that platinum-assisted chemical etching formed self-organized helical pores in silicon substrates can be utilized as platforms for the electrochemical production of nanohelices of conducting polymers (polypyrrole) and metals (gold). Surprisingly, the nanohelices thus created are tubes although the polymerization and deposition were carried out by anodic and cathodic reactions, respectively. Based on our results, we propose a common mechanism for the formation of tubular nanohelices by both anodic polymerization and cathodic deposition through the accumulation of reactants in microporous silicon which covers the wall surface of the helical pores

Aryl hydrocarbon receptor nuclear translocator in human liver is regulated by miR-24

Aryl hydrocarbon receptor nuclear translocator (ARNT) forms a heterodimer with aryl hydrocarbon receptor or hypoxia inducible factor 1α to mediate biological responses to xenobiotic exposure and hypoxia. Although the regulation mechanism of the ARNT expression is largely unknown, earlier studies reported that the human ARNT protein level was decreased by hydrogen peroxide or reactive oxygen species. These stimuli increase the miR-24 level in various human cell lines. In silico analysis predicts that some microRNAs including miR-16 and miR-23b may bind to ARNT mRNA. This background prompted us to investigate whether human ARNT is regulated by microRNAs. Overexpression of miR-24 into HuH-7 and HepG2 cells significantly decreased the ARNT protein level, but not the ARNT mRNA level, indicating translational repression. However, overexpression of miR-16 or miR-23b caused no change in the ARNT expression. The miR-24-dependent down-regulation of ARNT decreased the expression of its downstream genes such as CYP1A1 and carbonic anhydrase IX. Luciferase assay was performed to determine the element on the ARNT mRNA to which miR-24 binds. Finally, it was demonstrated that the miR-24 levels in a panel of 26 human livers were inversely correlated with the protein levels or the translational efficiency of ARNT. Taken together, we found that miR-24 negatively regulates ARNT expression in human liver, affecting the expression of its downstream genes. miR-24 would be one of the factors underlying the mechanisms by which ARNT protein is decreased by reactive oxygen species. © 2012 Elsevier Inc

Retinoid X receptor α in human liver is regulated by miR-34a

Retinoid X receptor α (RXRα) forms a heterodimer with numerous nuclear receptors to regulate drug- or lipid-metabolizing enzymes. In this study, we investigated whether human RXRα is regulated by microRNAs. Two potential recognition elements of miR-34a were identified in the RXRα mRNA: one in the coding region and the other in the 3′-untranslated region (3′-UTR). Luciferase assays revealed that miR-34a recognizes the element in the coding region. The overexpression of miR-34a in HepG2 cells significantly decreased the endogenous RXRα protein and mRNA levels. The stability of RXRα mRNA was decreased by the overexpression of miR-34a, indicating that miR-34a negatively regulates RXRα expression by facilitating mRNA degradation. We found that the miR-34a-dependent down-regulation of RXRα decreases the induction of CYP26 and the transactivity of CYP3A4. miR-34a has been reported to be up-regulated by p53, which has an ability to promote liver fibrosis. The p53 activation resulted in an increase of the miR-34a level and a decrease of the RXRα protein level. In addition, the miR-34a levels in eight fibrotic livers were higher than those in six normal livers, and the reverse trend was found for the RXRα protein levels. An inverse correlation was observed between the miR-34a and the RXRα protein levels in the 14 samples. Taken together, the data show that miR-34a negatively regulates RXRα expression in human liver, and affects the expression of its downstream genes. This miR-34a-dependent regulation might be the underlying mechanism responsible for the decreased expression of the RXRα protein in fibrotic livers. © 2014 Elsevier Inc

Emergencies after endoscopic procedures

Endoscopy adverse events (AEs), or complications, are a rising concern on the quality of endoscopic care, given the technical advances and the crescent complexity of therapeutic procedures, over the entire gastrointestinal and bilio-prancreatic tract. In a small percentage, not established, there can be real emergency conditions, as perforation, severe bleeding, embolization or infection. Distinct variables interfere in its occurrence, although, the awareness of the operator for their potential, early recognition, and local organized facilities for immediate handling, makes all the difference in the subsequent outcome. This review outlines general AEs’ frequencies, important predisposing factors and putative prophylactic measures for specific procedures (from conventional endoscopy to endoscopic cholangio-pancreatography and ultrasonography), with comprehensive approaches to the management of emergent bleeding and perforation

宅地化が進んだ地区のコミュニティセンターにおける乳幼児期の子育て支援と環境の現状

宅地化が進んだ地区のコミュティセンターを中心とした子育て支援と環境の現状を明らかにすることを目的として、小学校1年生の保護者を対象に、無記名のアンケート調査を行った。55名から回答を得（回答率71.4％）、回答者は全て母親であった。対象がストレスを感じた時期は、出生から1歳までが最も多くその原因は様々であったが、就業者より未就業者に多い傾向にあった。環境として「託児施設」は必要性が高いが満足度は低く、「医療機関」は必要性・満足度ともに高かった。また、コミュニティセンターの子育て支援22事業のうち、継続してほしい上位3つは就学後を対象にしたものであった

MAGIC and H.E.S.S. detect VHE gamma rays from the blazar OT081 for the first time: a deep multiwavelength study

https://pos.sissa.it/395/815/pdfPublished versio