Publications by authors named "Seiji Kojima"

Amber is a fragile (in Angell's classification) natural glass that has performed maturation processes over geological time. The terahertz dynamics of Baltic amber that was about 40 million years old were studied by terahertz time-domain spectroscopy (THz-TDS) in the frequency range of 0.2 and 6.

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On the 28th of June, 2024, we held a session focusing on bacterial motility at the International Union of Pure and Applied Biophysics Congress, held in Kyoto (IUPAB2024). This session was jointly chaired by Professor Seiji Kojima of Nagoya University and Associate Professor Matthew Baker of UNSW Sydney, highlighting significant advancements and discoveries in bacterial cellular mechanisms and motility, with six speakers each from different countries.

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Photosynthetic organisms have developed mechanisms to regulate light reactions in response to varying light conditions. Photosynthetic electron transport leads to the formation of a ΔpH across the thylakoid membrane (TM), which is crucial for regulating electron transport. However, other pH modulators remain to be identified, particularly in cyanobacteria.

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Amber is a unique example of a fragile glass that has been extensively aged below its glass transition temperature, thus reaching a state that is not accessible under normal experimental conditions. We studied the medium-range order of Baltic amber by x-ray diffraction (XRD) at high pressures. The pressure dependences of the low-angle XRD intensity between 0 and 5 Å^{-1} were measured from 0 to 7.

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The marine bacterium possesses a polar flagellum driven by a sodium ion flow. The main components of the flagellar motor are the stator and rotor. The C-ring and MS-ring, which are composed of FliG and FliF, respectively, are parts of the rotor.

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During the COVID-19 pandemic, excess deaths including cancer have become a concern in Japan, which has a rapidly aging population. Thus, this study aimed to evaluate how age-adjusted mortality rates (AMRs) for different types of cancer in Japan changed during the COVID-19 pandemic (2020-2022). Official statistics from Japan were used to compare observed annual and monthly AMRs with predicted rates based on pre-pandemic (2010-2019) figures using logistic regression analysis.

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The motility of species plays a pivotal role in their survival and adaptation to diverse environments and is intricately associated with pathogenicity in both humans and aquatic animals. Numerous mutant strains of have been generated using UV or EMS mutagenesis to probe flagellar motility using molecular genetic approaches. Identifying these mutations promises to yield valuable insights into motility at the protein structural physiology level.

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The marine bacterium has a single flagellum as a locomotory organ at the cell pole, which is rotated by the Na-motive force to swim in a liquid. The base of the flagella has a motor composed of a stator and rotor, which serves as a power engine to generate torque through the rotor-stator interaction coupled to Na influx through the stator channel. The MS-ring, which is embedded in the membrane at the base of the flagella as part of the rotor, is the initial structure required for flagellum assembly.

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The flagellar components of Vibrio spp., PomA and PomB, form a complex that transduces sodium ion and contributes to rotate flagella. The transmembrane protein PomB is attached to the basal body T-ring by its periplasmic region and has a plug segment following the transmembrane helix to prevent ion flux.

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Poisson's ratio is the fundamental metric used to discuss the performance of any material when strained elastically. However, the methods of the determination of Poisson's ratio are not yet discussed well. The first purpose of this paper is to introduce the five kinds of typical experimental methods to measure Poisson's ratio of glasses, ceramics, and crystals.

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Non-tuberculous mycobacterial infection (NTM) is rare in healthy children, with lymphadenitis being the most common presentation. Immunocompromised populations are known to be at high risk, but the clinical picture of NTM infection in pediatric hematology/oncology patients is unclear. In this nationwide retrospective analysis of patients under the age of 40 treated in Japanese pediatric hematology/oncology departments who developed NTM infection between January 2010 and December 2020, 36 patients were identified: 21 patients with hematopoietic stem cell transplantation (HSCT) and 15 non-transplant patients.

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Purpose: The MRE11-RAD50-NBN (MRN) complex plays a key role in recognizing and signaling DNA double-strand breaks. Pathogenic variants in NBN and MRE11 give rise to the autosomal-recessive diseases, Nijmegen breakage syndrome (NBS) and ataxia telangiectasia-like disorder, respectively. The clinical consequences of pathogenic variants in RAD50 are incompletely understood.

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We employed high-pressure Brillouin scattering to study the pressure dependencies of acoustic modes of glycerol up to 14 GPa at 300 K. We observed longitudinal acoustic velocities and transverse acoustic velocities for the first time from 5 to 14 GPa. The results allow the determination of a complete set of elastic properties and an accurate determination of the pressure-volume (P-V) equation of state (EOS).

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The FliG protein plays a pivotal role in switching the rotational direction of the flagellar motor between clockwise and counterclockwise. Although we previously showed that mutations in the Gly-Gly linker of FliG induce a defect in switching rotational direction, the detailed molecular mechanism was not elucidated. Here, we studied the structural changes in the FliG fragment containing the middle and C-terminal regions, named FliG, and the switch-defective FliG-G215A, using nuclear magnetic resonance (NMR) and molecular dynamics simulations.

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Background: Molecular analyses in hematological malignancies provide insights about genetic makeup. Probable etiological factors in leukemogenesis could also be disclosed. Since genetic analyses are still primitive in Iraq, a country of repeated wars, we conceived of performing next-generation sequencing (NGS), to disclose the genomic landscape of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) among a cohort of Iraqi children.

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Vibrio alginolyticus forms a single flagellum at its cell pole. FlhF and FlhG are known to be the main proteins responsible for the polar formation of single flagellum. MS-ring formation in the flagellar basal body appears to be an initiation step for flagellar assembly.

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Uniaxial ferroelectrics with tetragonal tungsten bronze structure are important functional materials with photorefractive, electrooptic, piezoelectric, and pyroelectric properties. SrBaNbO (SBN100) with > 50 is known as a typical uniaxial relaxor ferroelectric, while CaBaNbO (CBN100) undergoes nearly normal ferroelectric phase transitions. Single crystals of CSBN100 = [(CBN28) + (1 - ) (SBN61)] = CaBaNbO + (1 - ) SrBaNbO with nominal = 0.

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Article Synopsis
  • HLA mismatched unrelated donor transplantation poses risks like graft-versus-host disease (GVHD), graft failure, and infections, affecting patient health after the procedure.
  • A study assessed outcomes of 30 children who received bone marrow transplants from HLA 1 allele-mismatched donors using rabbit anti-thymocyte globulin (rATG) for GVHD prevention.
  • The results showed high overall survival (91.7%) and event-free survival (88.3%) rates, with manageable GVHD occurrences and no fatal viral infections, indicating a viable option for patients without a fully matched donor.
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The flagellar motor of marine Vibrio is driven by the sodium-motive force across the inner membrane. The stator complex, consisting of two membrane proteins PomA and PomB, is responsible for energy conversion in the motor. To understand the coupling of the Na flux with torque generation, it is essential to clearly identify the Na-binding sites and the Na flux pathway through the stator channel.

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The bacterial flagellum employs a rotary motor embedded on the cell surface. The motor consists of the stator and rotor elements and is driven by ion influx (typically H or Na) through an ion channel of the stator. Ion influx induces conformational changes in the stator, followed by changes in the interactions between the stator and rotor.

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