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Plasma Neurofilament Light Chain and Phosphorylated Tau Are Elevated in Myotonic Dystrophy Type 1
No full textBackground/Objectives: Myotonic dystrophy type 1 (DM1) is a multisystem disorder that affects the central nervous system. Despite previous studies, blood-based biomarkers have not been sufficiently characterized. This study investigated plasma neurofilament light chain (NfL), phosphorylated tau (p-tau181), amyloid-β (Aβ42/40), and glial fibrillary acidic protein (GFAP) in a Japanese cohort with DM1 to assess their potential as biomarkers. Methods: Forty patients with genetically confirmed DM1 were enrolled in this study. Plasma NfL, p-tau181, Aβ42/40, and GFAP were quantified using single-molecule array technology. Clinical and genetic variables, including age, CTG repeat size, Mini-Mental State Examination (MMSE) score, modified Rankin Scale (mRS) score, and creatine kinase levels, were analyzed for correlations. Results: NfL and p-tau181 were significantly elevated in patients with DM1 compared with controls, with 95% exceeding the p-tau181 cut-off. NfL was moderately correlated with age, age at onset, and mRS, and no significant associations were observed between p-tau181 and other biomarkers, although a correlation was noted with serum creatine kinase. Conclusions: These findings support that NfL is a marker of disease severity in DM1 and identified plasma p-tau181 as a potential novel biomarker. While the mechanisms underlying the increased p-tau181 levels remain unclear, they may reflect DM1-related pathologies in the brain and possibly in skeletal muscle. Study limitations include a small sample size and lack of age-matched controls, highlighting the need for longitudinal validation. This study demonstrates the utility of NfL and suggests that p-tau181 is an emerging biomarker for DM1, supporting future work toward biomarker-guided monitoring and therapeutic evaluation.journal articl
励起状態ポジトロニウムのシリカナノ空孔中における単寿命崩壊現象の研究
No full textポジトロニウム(Ps)にはたらく重力の精密測定やPs-BECを光源としたガンマ線レーザーの実現などを目指し、反物質系で初となるPsのボース・アインシュタイン凝縮をに向けた研究を行っている。これにはPsの寿命142nsの間に10 K以下に高速冷却する技術が必要である。これまで原理実証として真空中でのPs一次元レーザー冷却に成功している。これを発展させ、ナノ空孔中に生成したPsを閉じ込めたままレーザー冷却する技術の開発を行っている。Psレーザー冷却では1S⇔2P間の励起・脱励起サイクルを50 回程度繰り返す必要があるが、現状では2P励起状態でガンマ線に崩壊する現象が生じ、励起・脱励起サイクルを回せない。このメカニズム解明を現在進めている。KEK低速陽電子実験施設においてシリカエアロゲル中に生成したPsに1S→2P励起用243 nm紫外パルスレーザーを照射し、ガンマ線検出器信号の変化を測定した。また、Ps生成からレーザー照射までの遅延時間を変化させることで、熱化冷却により励起前のPs温度を変化させ、Ps温度依存性を調べた。励起状態PsとPs温度に強い相関が見られ、励起状態Psがナノ空孔壁と衝突することにより崩壊するというモデルを支持する結果となった。今後は、Ps温度（運動エネルギー）やPs生成材の空孔構造（空孔径）および化学組成を系統的に変化させて測定行う。京都大学複合原子力科学研究所専門研究会conference presentatio
Ultrafast observation of shock wave formation in aluminum under direct femtosecond laser irradiation
No full textShock wave formation in aluminum after the direct irradiation of a femtosecond laser pulse with an intensity of 1014 W/cm2 onto the metal surface in air was observed using frequency-domain interferometry with picosecond temporal resolution. This high resolution allows us to accurately evaluate arrival time and rise time of the wave before and after shock wave formation. The temporal evolution of the rear surface velocity of the metal film had an ultrafast rise at the wavefront of less than 5 ps and a two-wave structure. As the incident pump laser energy decreased or the metal film thickness increased, the amplitude of the first wave decayed and the time separation between the two waves increased. The relationship between the particle velocity and shock velocity indicated that aluminum was elastically compressed in a longitudinal stress of 185 GPa, reaching a strain of approximately 30%. The estimated elastic strain rate was 6 × 1010 s−1 at 500 nm in depth. Through a thermal nonequilibrium state in the early stage, aluminum becomes a metastable elastic Hugoniot state under such high longitudinal stress in a region deeper than the diffusion length of laser-heated electrons.journal articl
The HP1 box of KAP1 organizes HP1α for silencing of endogenous retroviral elements in embryonic stem cells
No full textRepression of endogenous retroviral elements (ERVs) is facilitated by KAP1 (KRAB-associated protein 1)-containing complexes, however the underlying mechanism remains unclear. Here, we show that binding of KAP1 to the major component of the heterochromatin spreading and maintenance network, HP1α, plays a critical role in silencing of repetitive elements. Structural, biochemical and mutagenesis studies demonstrate that the association of the HP1 box of KAP1 (KAP1Hbox) with the chromoshadow domain of HP1α (HP1αCSD) leads to a symmetrical arrangement of HP1αCSD and multimerization that may promote the closed state of chromatin. The formation of the KAP1Hbox-HP1αCSD complex enhances charge driven DNA binding and phase separation activities of HP1α. ChIP-seq and ATAC-seq analyses using KAP1 knock out mouse embryonic stem cells expressing wild type KAP1 or HP1-deficient KAP1 mutant show that in vivo, KAP1 engagement with HP1 is required for maintaining inaccessible chromatin at ERVs. Our findings provide mechanistic and functional insights that further our understanding of how ERVs are silenced.journal articl
放射線腸管障害の治療にMuse細胞が有望であることを発見
No full text放射線療法に伴う腸管をはじめとした消化管の副作用に対する有効な治療法はまだない。我々は、放射線腸管障害モデルマウスにヒト骨髄由来Muse細胞（hBM-Muse細胞）を静脈投与した結果、投与したhBM-Muse細胞が障害を受けた腸管に集積（ホーミング）すること、およびhBM-Muse細胞の投与により腸管障害が軽減されることを明らかにした。本稿では、これらの結果を示す実験データを中心に紹介する。加えて、「なぜMuse細胞が障害部位に集まるのか」「なぜMuse細胞には高い治療効果があるのか」についても、最近の実験データから考察する。journal articl
Ar-irradiation effects on graphite thin film revealed from first-principles based simulations
No full textThe Ar-irradiation effects on graphite thin film have been investigated using first-principles MD simulations. We introduced a novel damping medium to avoid artifacts due to periodic boundary conditions. This methodology allows to elucidate the detailed processes of the defect formation. We find that the irradiation of our graphite sample with 380 keV Ar tends to create di-vacancies in graphene sheets. This process is due to intralayer displacements of the C atom targeted by the incoming Ar. The inclusion of di-vacancies in the irradiated samples is proved by comparing our simulated Raman spectra with the experimental ones.journal articl
Ultrafast Optical Control of Multi-Valley States in 2D SnS
No full textWe theoretically study the ultrafast optical control of multiple valley states in two‐dimensional (2D) tin sulfide (SnS) monolayers, a member of the layered group-IV monochalcogenides, which is a promising class of materials for overcoming current challenges in valleytronics. By combining time‐dependent density functional theory with Maxwell’s equations, we simulate how both linearly and circularly polarized ultrashort laser pulses affect the electronic excitation dynamics and valley polarization in SnS. Our results reveal that the corrugated phosphorene like crystal structure of SnS monolayers leads to the emergence of both linear and circular dichroism, allowing flexible manipulation of multi-valley excitation by simply adjusting the light polarization. Moreover, the interplay between broken inversion symmetry and spin-orbit coupling gives rise to distinct Berry curvature effects and spin valley coupling, thereby enabling circular dichroism. Furthermore, we propose that tuning the carrier‐envelope phase of few-cycle femtosecond laser pulses can achieve sub‐cycle, ultrafast switching among multiple valley states. These findings not only deepen our understanding of valley dynamics in 2D materials but may also open new avenues for the development of valleytronic devices.journal articl
Radon-thoron exhalation and emanation determinations from mylonitic rock samples collected in north Abu Rusheid, Egypt
No full textMylonitic rocks in north Abu Rusheid, Egypt, contain naturally occurring radioactive materials (NORMs), making them potential sources of indoor radon (Rn) and thoron (Tn) exposure when used as building materials. Furthermore, they pose occupational exposure risks for miners. Rn mass exhalation rate (RnEX), Tn mass exhalation rate (TnEX), Rn emanation fraction (RnEM), and Tn emanation fraction (TnEM) were evaluated simultaneously in 27 mylonitic rock samples collected from three trenches (TCHA, TCHB, and TCHC) in the area. The powder sandwich technique has been carried out using a RAD7 detector to assess RnEX and TnEX. Additionally, gamma spectroscopy was used to evaluate RnEM and TnEM parameters. The RnEX and TnEX values varied from 0.10 to 1.13 and 83 to 5757 Bq kg−1 h−1, respectively, while the RnEM and TnEM values ranged from 0.055 to 0.182 and 0.017 to 0.078, respectively. The activity concentrations of 226Ra and 232Th varied from 127 to 1524 and 96 to 2420 Bq kg−1, respectively, and the mean values exceeded the worldwide average values of 33 and 45 Bq kg−1, respectively. Positive correlations between 226Ra and RnEX, and 232Th and TnEX were observed among the trenches. However, no systematic relations were identified between 226Ra and RnEM, 232Th and TnEM, or 226Ra and 232Th, which could be attributed to geological factors. The findings of this study highlighted the potential radiation hazards associated with mylonitic rock use in construction and mining, emphasizing the need for radioprotection measures.journal articl
Real-time XRD analysis of GaN remote epitaxy on sapphire substrates covered with directly grown graphene
No full textRemote epitaxy is a thin-film growth technique in which a material is epitaxially grown on a substrate through a two-dimensional (2D) interlayer. The weak van der Waals (vdW) interaction enables easy exfoliation of the grown film, facilitating flexible and transferable devices. Moreover, remote epitaxy allows strain in the grown material to relax spontaneously, even in lattice-mismatched systems, enabling the growth of high-quality heteroepitaxial thin films. In this study, we investigate the role of 2D materials in strain relaxation by examining the lattice deformation of GaN crystals during remote epitaxy on c-plane sapphire, with and without 2D interlayers, using real-time X-ray diffraction. Significant differences are observed in the initial strain magnitude: the highest on bare sapphire, the lowest on graphene/sapphire, and an intermediate level on hexagonal boron nitride (h-BN)/sapphire. These results confirm that weak vdW interactions promote early-stage lattice relaxation. Additionally, non-polar graphene is found to be more effective for strain relaxation than polar h-BN. The insights gained from this study on the initial growth process of GaN are expected to contribute to the advancement of ultra-thin, highly flexible GaN film production techniques.journal articl
シンチレータの進歩がもたらす核医学の発展
No full textScintillators are essential components of gamma cameras and PET scanners, both key imaging systems in nuclear medicine. Following radiopharmaceutical administration, gamma rays emitted from the body first interact with the scintillator, generating photoelectrons that are subsequently processed to produce clinical images. Enhancing scintillator performance can drive advancements in nuclear medicine. While gamma camera imaging, including SPECT, utilizes various radiopharmaceuticals labeled with isotopes such as 123I and 99mTc, its performance remains insufficient for clinical applications among recent medical advances. In this regard, PET imaging surpasses gamma cameras in resolution and sensitivity, expected to be utilized more extensively. Furthermore, fast-decay scintillators enable time-of-flight gamma-ray measurement, significantly improving spatial resolution and reducing noise. PET holds the greatest promise particularly in neuroscience, given the brain’s complexity and limitations in invasive measurement. Notably, PET remains the only modality capable of quantitative imaging of deep brain regions.journal articl