Showing papers by "Tokyo University of Science published in 2021"

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

Abstract: In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

Coronavirus disease 2019 (COVID-19): An overview of the immunopathology, serological diagnosis and management.

Abstract: SARS-CoV-2 is a novel human coronavirus responsible for the Coronavirus disease 2019 (COVID-19) pandemic. Pneumonia and acute respiratory distress syndrome are the major complications of COVID-19. SARS-CoV-2 infection can activate innate and adaptive immune responses and result in massive inflammatory responses later in the disease. These uncontrolled inflammatory responses may lead to local and systemic tissue damage. In patients with severe COVID-19, eosinopenia and lymphopenia with a severe reduction in the frequency of CD4+ and CD8+ T cells, B cells and natural killer (NK) cells are a common feature. COVID-19 severity hinges on the development of cytokine storm characterized by elevated serum levels of pro-inflammatory cytokines. Moreover, IgG-, IgM- and IgA-specific antibodies against SARS-CoV-2 can be detected in most patients, along with the viral RNA, forming the basis for assays that aid in patient diagnosis. Elucidating the immunopathological outcomes due to COVID-19 could provide potential targets for immunotherapy and are important for choosing the best clinical management by consultants. Currently, along with standard supportive care, therapeutic approaches to COVID-19 treatment involve the use of antiviral agents that interfere with the SARS-CoV-2 lifecycle to prevent further viral replication and utilizing immunomodulators to dampen the immune system in order to prevent cytokine storm and tissue damage. While current therapeutic options vary in efficacy, there are several molecules that were either shown to be effective against other viruses such as HIV or show promise in vitro that could be added to the growing arsenal of agents used to control COVID-19 severity and spread.

MgO-Template Synthesis of Extremely High Capacity Hard Carbon for Na-Ion Battery

Abstract: Extremely high capacity hard carbon for Na-ion battery, delivering 478 mAh g-1 , is successfully synthesized by heating a freeze-dried mixture of magnesium gluconate and glucose by a MgO-template technique. Influences of synthetic conditions and nano-structures on electrochemical Na storage properties in the hard carbon are systematically studied to maximize the reversible capacity. Nano-sized MgO particles are formed in a carbon matrix prepared by pre-treatment of the mixture at 600 °C. Through acid leaching of MgO and carbonization at 1500 °C, resultant hard carbon demonstrates an extraordinarily large reversible capacity of 478 mAh g-1 with a high Coulombic efficiency of 88 % at the first cycle.

Universal Relation between Instantaneous Diffusivity and Radius of Gyration of Proteins in Aqueous Solution

Abstract: Protein conformational fluctuations are highly complex and exhibit long-term correlations. Here, molecular dynamics simulations of small proteins demonstrate that these conformational fluctuations directly affect the protein's instantaneous diffusivity D_{I}. We find that the radius of gyration R_{g} of the proteins exhibits 1/f fluctuations that are synchronous with the fluctuations of D_{I}. Our analysis demonstrates the validity of the local Stokes-Einstein-type relation D_{I}∝1/(R_{g}+R_{0}), where R_{0}∼0.3 nm is assumed to be a hydration layer around the protein. From the analysis of different protein types with both strong and weak conformational fluctuations, the validity of the Stokes-Einstein-type relation appears to be a general property.

Cholesterol-functionalized DNA/RNA heteroduplexes cross the blood–brain barrier and knock down genes in the rodent CNS

Abstract: Achieving regulation of endogenous gene expression in the central nervous system (CNS) with antisense oligonucleotides (ASOs) administered systemically would facilitate the development of ASO-based therapies for neurological diseases. We demonstrate that DNA/RNA heteroduplex oligonucleotides (HDOs) conjugated to cholesterol or α-tocopherol at the 5′ end of the RNA strand reach the CNS after subcutaneous or intravenous administration in mice and rats. The HDOs distribute throughout the brain, spinal cord and peripheral tissues and suppress the expression of four target genes by up to 90% in the CNS, whereas single-stranded ASOs conjugated to cholesterol have limited activity. Gene knockdown was observed in major CNS cell types and was greatest in neurons and microglial cells. Side effects, such as thrombocytopenia and focal brain necrosis, were limited by using subcutaneous delivery or by dividing intravenous injections. By crossing the blood–brain barrier more effectively, cholesterol-conjugated HDOs may overcome the limited efficacy of ASOs targeting the CNS without requiring intrathecal administration. Genes in the rodent brain are knocked down by DNA/RNA heteroduplexes injected intravenously.

Creation of High-Performance Heterogeneous Photocatalysts by Controlling Ligand Desorption and Particle Size of Gold Nanocluster

Abstract: Recently, the creation of new heterogeneous catalysts using the unique electronic/geometric structures of small metal nanoclusters (NCs) has received considerable attention. However, to achieve this, it is extremely important to establish methods to remove the ligands from ligand-protected metal NCs while preventing the aggregation of metal NCs. In this study, the ligand-desorption process during calcination was followed for metal-oxide-supported 2-phenylethanethiolate-protected gold (Au) 25-atom metal NCs using five experimental techniques. The results clearly demonstrate that the ligand-desorption process consists of ligand dissociation on the surface of the metal NCs, adsorption of the generated compounds on the support and desorption of the compounds from the support, and the temperatures at which these processes occurred were elucidated. Based on the obtained knowledge, we established a method to form a metal-oxide layer on the surface of Au NCs while preventing their aggregation, thereby succeeding in creating a water-splitting photocatalyst with high activity and stability.

Hierarchical structures hydrogel evaporator and superhydrophilic water collect device for efficient solar steam evaporation

Abstract: Efficient light absorption and trapping are of vital importance for the solar water evaporation by hydrogel-based photothermal conversion materials. Conventional strategies are focused on the development of the composition and structure of the hydrogel's internal network. In our point of view, the importance of the surface structure of hydrogel has usually been underestimated or ignored. Here inspired by the excellent absorbance and water transportation ability of biological surface structure, the hierarchical structured hydrogel evaporators (HSEs) increased the light absorption, trapping, water transportation and water-air interface, which is the beneficial photothermal conversion and water evaporation. The HSEs showed a rapid evaporation rate of 1.77 kg·m-2·h-1 at about 92% energy efficiency under one sun (1 kW·m-2). Furthermore, the superhydrophilic window device was used in this work to collect the condensed water, which avoids the light-blocking caused by the water mist formed by the small droplets and the problem of the droplets stick on the device dropping back to the bulk water. Integrated with the excellent photothermal conversion hydrogel and superhydrophilic window equipment, this work provides efficient evaporation and desalination of hydrogel-based solar evaporators in practical large-scale applications.

Thiolate-Protected Metal Nanoclusters: Recent Development in Synthesis, Understanding of Reaction, and Application in Energy and Environmental Field.

Abstract: Metal nanoclusters (NCs), which are composed of about 250 or fewer metal atoms, possess great potential as novel functional materials. Fundamental research on metal NCs gradually started in the 1960s, and since 2000, thiolate (SR)-protected metal NCs have been the main metal NCs actively studied. The precise and systematic isolation of SR-protected metal NCs has been achieved in 2005. Since then, research on SR-protected metal NCs for both basic science and practical application has rapidly expanded. This review describes this recent progress in the field of SR-protected metal NCs in three areas: synthesis, understanding, and application. Specifically, the recent study of alloy NCs and connected structures composed of NCs is highlighted in the "synthesis" section, recent knowledge on the reactivity of NCs in solution is highlighted in the "understanding" section, and the applications of NCs in the energy and environmental field are highlighted in the "application" section. This review provides insight on the current state of research on SR-protected metal NCs and discusses the challenges to be overcome for further development in this field as well as the possibilities that these materials can contribute to solving the problems facing modern society.

Visible light-assisted photocatalysis using spherical-shaped bivo4 photocatalyst

Abstract: In this research work, we reported the synthesis of a spherical-shaped bismuth vanadate (BiVO4) photocatalyst using a cost-effective, simple, chemical hydrothermal method and studied the effect of deposition temperatures on the structural, morphological, optical properties, etc The XRD result confirmed the monoclinic scheelite phase of BiVO4 An XPS study confirmed the occurrence of Bi, V, and O elements and also found that Bi and V exist in +3 and +5 oxidation states, respectively SEM micrographs revealed the spherical-shaped morphology of the BiVO4 photocatalyst Optical investigation showed that the bandgap of the BiVO4 photocatalyst varied between 225 and 232 eV The as-synthesized BiVO4 photocatalyst was used to study the photocatalytic degradation of crystal violet (CV) dye under visible light illumination The photocatalytic degradation experiment showed that the degradation percentage of crystal violet dye using BiVO4 reached 9821% after 120 min Mineralization of crystal violet dye was studied using a chemical oxygen demand analysis

Photocatalytic degradation of Rhodamine B using graphitic carbon nitride photocatalyst

Abstract: In this work, a graphitic carbon nitride (g-C3N4) photocatalyst was synthesized by pyrolysis of melamine. The effect of different synthesis temperatures on the structural, morphological, and optical properties of the g-C3N4 photocatalyst was investigated. X-ray diffraction and Raman spectroscopic analyses confirmed the formation of the g-C3N4 photocatalyst. The elemental composition and valence states of the g-C3N4 photocatalyst were studied using X-ray photoelectron spectroscopy. A specific surface area of 25.45 m2/g was measured using the BET technique. UV–Vis spectroscopy showed that the g-C3N4 photocatalyst exhibited good absorbance in the ultraviolet and visible regions. The photocatalytic performance of the g-C3N4 photocatalyst was tested for the degradation of Rhodamine B under sunlight illumination.

Advanced two-dimensional heterojunction photocatalysts of stoichiometric and non-stoichiometric bismuth oxyhalides with graphitic carbon nitride for sustainable energy and environmental applications

Abstract: Semiconductor-based photocatalysis has been identified as an encouraging approach for solving the two main challenging problems, viz., remedying our polluted environment and the generation of sustainable chemical energy. Stoichiometric and non-stoichiometric bismuth oxyhalides (BiOX and BixOyXz where X = Cl, Br, and I) are a relatively new class of semiconductors that have attracted considerable interest for photocatalysis applications due to attributes, viz., high stability, suitable band structure, modifiable energy bandgap and two-dimensional layered structure capable of generating an internal electric field. Recently, the construction of heterojunction photocatalysts, especially 2D/2D systems, has convincingly drawn momentous attention practicably owing to the productive influence of having two dissimilar layered semiconductors in face-to-face contact with each other. This review has systematically summarized the recent progress on the 2D/2D heterojunction constructed between BiOX/BixOyXz with graphitic carbon nitride (g-C3N4). The band structure of individual components, various fabrication methods, different strategies developed for improving the photocatalytic performance and their applications in the degradation of various organic contaminants, hydrogen (H2) evolution, carbon dioxide (CO2) reduction, nitrogen (N2) fixation and the organic synthesis of clean chemicals are summarized. The perspectives and plausible opportunities for developing high performance BiOX/BixOyXz-g-C3N4 heterojunction photocatalysts are also discussed.

Interleukin-11-expressing fibroblasts have a unique gene signature correlated with poor prognosis of colorectal cancer.

Abstract: Interleukin (IL)-11 is a member of the IL-6 family of cytokines and is involved in multiple cellular responses, including tumor development. However, the origin and functions of IL-11-producing (IL-11+) cells are not fully understood. To characterize IL-11+ cells in vivo, we generate Il11 reporter mice. IL-11+ cells appear in the colon in murine tumor and acute colitis models. Il11ra1 or Il11 deletion attenuates the development of colitis-associated colorectal cancer. IL-11+ cells express fibroblast markers and genes associated with cell proliferation and tissue repair. IL-11 induces the activation of colonic fibroblasts and epithelial cells through phosphorylation of STAT3. Human cancer database analysis reveals that the expression of genes enriched in IL-11+ fibroblasts is elevated in human colorectal cancer and correlated with reduced recurrence-free survival. IL-11+ fibroblasts activate both tumor cells and fibroblasts via secretion of IL-11, thereby constituting a feed-forward loop between tumor cells and fibroblasts in the tumor microenvironment.

ADAR1 RNA editing enzyme regulates R-loop formation and genome stability at telomeres in cancer cells

Abstract: ADAR1 is involved in adenosine-to-inosine RNA editing. The cytoplasmic ADAR1p150 edits 3’UTR double-stranded RNAs and thereby suppresses induction of interferons. Loss of this ADAR1p150 function underlies the embryonic lethality of Adar1 null mice, pathogenesis of the severe autoimmune disease Aicardi-Goutieres syndrome, and the resistance developed in cancers to immune checkpoint blockade. In contrast, the biological functions of the nuclear-localized ADAR1p110 remain largely unknown. Here, we report that ADAR1p110 regulates R-loop formation and genome stability at telomeres in cancer cells carrying non-canonical variants of telomeric repeats. ADAR1p110 edits the A-C mismatches within RNA:DNA hybrids formed between canonical and non-canonical variant repeats. Editing of A-C mismatches to I:C matched pairs facilitates resolution of telomeric R-loops by RNase H2. This ADAR1p110-dependent control of telomeric R-loops is required for continued proliferation of telomerase-reactivated cancer cells, revealing the pro-oncogenic nature of ADAR1p110 and identifying ADAR1 as a promising therapeutic target of telomerase positive cancers. One type of RNA editing involves ADAR-mediated conversion of adenosine to inosine. Here the authors show that ADAR1 nuclear isoform p110 regulates R loop formation and genome stability at telomeres in cancer cells.

Synthesis of N-doped TiO2 for efficient photocatalytic degradation of atmospheric NOx

Abstract: Titanium oxide (TiO2) is a potential photocatalyst for removing toxic NOx from the atmosphere. Its practical application is, however, significantly limited by its low absorption into visible light and a high degree of charge recombination. The overall photocatalytic activity of TiO2 remains too low since it can utilize only about 4–5% of solar energy. Nitrogen doping into the TiO2 lattice takes advantage of utilizing a wide range of solar radiation by increasing the absorption capability towards the visible light region. In this work, N-doped TiO2, referred to as TC, was synthesized by a simple co-precipitation of tri-thiocyanuric acid (TCA) with P25 followed by heat treatment at 550 degrees C. The resulting nitrogen doping increased the visible-light absorption and enhanced the separation/transfer of photo-excited charge carriers by capturing holes by reduced titanium ions. As a result, TC samples exhibited excellent photocatalytic activities of 59% and 51% in NO oxidation under UV and visible light irradiation, in which the optimum mass ratio of TCA to P25 was found to be 10.

Visualization of the strain-induced topological phase transition in a quasi-one-dimensional superconductor TaSe3

Abstract: Control of the phase transition from topological to normal insulators can allow for an on/off switching of spin current. While topological phase transitions have been realized by elemental substitution in semiconducting alloys, such an approach requires preparation of materials with various compositions. Thus it is quite far from a feasible device application, which demands a reversible operation. Here we use angle-resolved photoemission spectroscopy and spin- and angle-resolved photoemission spectroscopy to visualize the strain-driven band-structure evolution of the quasi-one-dimensional superconductor TaSe3. We demonstrate that it undergoes reversible strain-induced topological phase transitions from a strong topological insulator phase with spin-polarized, quasi-one-dimensional topological surface states, to topologically trivial semimetal and band insulating phases. The quasi-one-dimensional superconductor TaSe3 provides a suitable platform for engineering the topological spintronics, for example as an on/off switch for a spin current that is robust against impurity scattering.

IL-10 in Mast Cell-Mediated Immune Responses: Anti-Inflammatory and Proinflammatory Roles.

Abstract: Mast cells (MCs) play critical roles in Th2 immune responses, including the defense against parasitic infections and the initiation of type I allergic reactions. In addition, MCs are involved in several immune-related responses, including those in bacterial infections, autoimmune diseases, inflammatory bowel diseases, cancers, allograft rejections, and lifestyle diseases. Whereas antigen-specific IgE is a well-known activator of MCs, which express FceRI on the cell surface, other receptors for cytokines, growth factors, pathogen-associated molecular patterns, and damage-associated molecular patterns also function as triggers of MC stimulation, resulting in the release of chemical mediators, eicosanoids, and various cytokines. In this review, we focus on the role of interleukin (IL)-10, an anti-inflammatory cytokine, in MC-mediated immune responses, in which MCs play roles not only as initiators of the immune response but also as suppressors of excessive inflammation. IL-10 exhibits diverse effects on the proliferation, differentiation, survival, and activation of MCs in vivo and in vitro. Furthermore, IL-10 derived from MCs exerts beneficial and detrimental effects on the maintenance of tissue homeostasis and in several immune-related diseases including contact hypersensitivity, auto-immune diseases, and infections. This review introduces the effects of IL-10 on various events in MCs, and the roles of MCs in IL-10-related immune responses and as a source of IL-10.

Radical-Based Coordination Polymers as a Platform for Magnetoluminescence

Abstract: Spin-correlated electronic and magnetic properties of organic radicals have been developed, but luminescence properties, based on interplay with spins, have rarely been reported. The effect of magn...

Gate-based superconducting quantum computing

Abstract: In this Tutorial, we introduce basic conceptual elements to understand and build a gate-based superconducting quantum computing system.