Electrical Cell-substrate Impedance Sensing (ECIS)法を用いた培養細胞の微細挙動の定量的評価法 - 細胞-細胞間隙と細胞-電極間隙の評価 -

We have proposed a mathematical model for the micro-dynamics for cultured cells measured with ECIS system for the detection of nanometer-order dynamics of cells cultured on a small gold electrode and could separately evaluate cell-to-cell distance (A) and cell-to-substrate distance (h). For wide applications of this method, we constructed mathematical models which express cell-to-electrode impedances for some kinds of confluent conditions. Based on this mathematical model, we defined new parameters S(A) and S(h) in order to evaluate cell-to-cell distance and cell-to-substrate distance. As the application, we investigated the effect of X-irradiation to bovine aortic endothelial cell (BAEC). We analyzed the micro-dynamics of cells from the impedance of BAEC before and after X-irradiation. It was proved that the stimulation of 100 Gy X-irradiation to the BAEC resulted in the large scale of increase in the cell-to-cell distances (A), and the slight increase in the cell-to-substrate distances (h) accompany with continuous fluctuations.[背景] Electrical Cell-substrate Impedance Sensing (ECIS)は培養細胞の電気的計測により,その微細挙動を評価する工学的手法である｡我々はECISを用いてこの微細挙動を細胞-細胞間隙と細胞-電極間隙に分離して推定することが可能な数学的モデルを提案してきた｡本研究ではこの数学的モデルを使用して,Ⅹ線を照射した牛大動脈内皮細胞(bovine aortic endothelial cell : BAEC)の微細挙動の経時変化を評価した｡ [方法と結果] ECISシステム(Model 1600R Applied BioPhysics)を用いてBAECのコンフルエント到達前後で計測を行い,数学的モデルを構築した｡このモデルは細胞の微細挙動を検出するために重要な周波数レンジである1-10kHzにおいて測定結果とよく一致し,Cole-Cole円弧則に従う｡さらに細胞-細胞間距離Aの増減に対応する校正定数S(A)と細胞-電極間距離hの増減に対応する校正定数S(h)を導入し,ベクトルインピーダンスの変化に対応した値を算出することで細胞の微細挙動を評価することとした｡次に本法によりX線(150kV, 100Gy)を照射したBAECの微細挙動を評価した｡Ⅹ線照射細胞では時間経過と共に抵抗成分の変化が支配的なインピーダンスの減少が確認された｡この現象はS(A)の大きな増加とS(h)の微小な減少をもたらした｡このパラメータの変化は細胞間隙が拡大したことを示しており,Ⅹ線照射による細胞内損傷により細胞密度が低下したと考えられた｡ [結論] 本法は培養細胞の微細動態の変化を細胞-細胞間隙と細胞-電極間隙に分けてリアルタイムに定量評価することが可能であり,各臓器の細胞レベルでの薬物の治療効果や Ⅹ線に対する耐性の評価に適応できるものと考える

Shallow and deep trap states of solvated electrons in methanol and their formation, electronic excitation, and relaxation dynamics

We present condensed-phase first-principles molecular dynamics simulations to elucidate the presence of different electron trapping sites in liquid methanol and their roles in the formation, electronic transitions, and relaxation of solvated electrons (emet−) in methanol. Excess electrons injected into liquid methanol are most likely trapped by methyl groups, but rapidly diffuse to more stable trapping sites with dangling OH bonds. After localization at the sites with one free OH bond (1OH trapping sites), reorientation of other methanol molecules increases the OH coordination number and the trap depth, and ultimately four OH bonds become coordinated with the excess electrons under thermal conditions. The simulation identified four distinct trapping states with different OH coordination numbers. The simulation results also revealed that electronic transitions of emet− are primarily due to charge transfer between electron trapping sites (cavities) formed by OH and methyl groups, and that these transitions differ from hydrogenic electronic transitions involving aqueous solvated electrons (eaq−). Such charge transfer also explains the alkyl-chain-length dependence of the photoabsorption peak wavelength and the excited-state lifetime of solvated electrons in primary alcohols

Characterization of the effect of ion irradiation on industrially produced GdBa₂Cu₃O₇−δ superconducting tapes using a slow positron beam

To investigate the effect of irradiation-induced defects on the superconducting characteristics of industrially produced superconductor—GdBa₂Cu₃O₇−δ (GdBCO)—coated conductors (CCs), we irradiated the GdBCO CCs with Au ions at 2 or 10 MeV and probed them using a slow positron beam. Vacancy clusters were detected in both unirradiated and irradiated GdBCO CCs. However, the effect of ion irradiation on the GdBCO CCs was characterized as a slight reduction in the positron annihilation rate with low-momentum electrons. We also found a correlation between the annihilation rate of low-momentum electrons and the superconducting transition temperature

Relationship Between Brain Activity and Real-Road Driving Behavior: A Vector-Based Whole-Brain Functional Near-Infrared Spectroscopy Study

Automobile driving requires multiple brain functions. However, the brain regions related to driving behavior are unknown. Therefore, we measured activity of the frontal, parietal and occipital lobes during driving using functional near-infrared spectroscopy (fNIRS). Cortical activation patterns were examined in relation to driving behaviors, such as steering motion, accelerator pedal motion, and speed control. Six healthy adults participated in the experiment. Cerebral oxygen exchange (COE) was calculated based on the oxyhemoglobin and deoxyhemoglobin concentrations measured by fNIRS. The COE and driving behavior data were collected every 1 m and averaged for all subjects. Functional NIRS data for all 98 channels were extracted using principal component analysis. Similarity between extracted components and driving behaviors were confirmed by |cosine similarity|\u3e0.3. Among the factors with confirmed similarity, we identified brain regions with high principal component loading (|PCL|\u3e0.4). Among the 16 COE factors extracted, COE factor 1 and factor 5 exhibited similarity with steering motion (cosine similarity: factor 1, -0.538; factor 5, 0.551). The PCLs of COE factor 1 and factor 5 were high in the frontal lobe (Brodmann areas [BAs] 9, 8, and 4/3) (PCL\u3e0.8). COE factor 6 exhibited a similarity with accelerator pedal motion (cosine similarity: 0.369), and the PCL of COE factor 6 was highest in the parietal lobe (BA7) (PCL= -0.62). Speed control did not exhibit similarity with any COE factor. These findings will contribute to the selection of brain measurement areas when fNIRS is used for vehicle driving assessment

Strain-induced microstructural rearrangement in ultra-high molecular weight polyethylene for hip joints: A comparison between conventional and vitamin E-infused highly-crosslinked liners

Infusion of vitamin E. (alpha-tocopherol) in highly crosslinked ultra-high molecular weight polyethylene (UHMWPE) liners has been conceived to achieve superior oxidation stability while preserving enhanced mechanical properties as compared to post-irradiation remelted liners. However, the presence of an antioxidant in the material microstructure brings an issue of concern in whether a "foreign substance" might reduce radiation crosslinking efficiency and/or change microstructural characteristics by diffusing into UHMWPE. The key to clarify this fundamental issue resides in performing a quantitative evaluation of the obtained material structure and its polymeric chain mobility on the molecular scale. In this paper, a Raman spectroscopic examination is presented of molecular orientation and phase fractions in as-processed vitamin E-infused UHMWPE acetabular liners in comparison with a model (undoped and unirradiated/uncrosslinked) and a conventional (undoped and 33 kGy-sterilized by gamma-irradiation) UHMWPE liners. The microstructural responses of structurally different liners to externally applied compressive strain were also monitored. The main results of the spectroscopic analyses can be summarized as follows: (i) preliminary gamma irradiation reduced the fraction of amorphous phase and increased the degree of molecular alignment, the vitamin E-infused liner preserving the crystallinity level achieved by the 100-kGy irradiation injected before infusion; (ii) the presence of vitamin E significantly promoted orientational randomness, which increased with increasing compressive strain magnitude, a phenomenon beneficial to minimize strain-softening-assisted wear phenomena. (C) 2012 Elsevier Ltd. All rights reserved

Time- and Angle-Resolved Photoemission Spectroscopy of Hydrated Electrons Near a Liquid Water Surface

世界で初めて、溶液反応の超高速時間・角度分解光電子分光に成功 --溶液化学反応の機構解明に前進--. 京都大学プレスリリース. 2014-04-22.We present time- and angle-resolved photoemission spectroscopy of trapped electrons near liquid surfaces. Photoemission from the ground state of a hydrated electron at 260 nm is found to be isotropic, while anisotropic photoemission is observed for the excited states of 1, 4-diazabicyclo[2, 2, 2]octane and I− in aqueous solutions. Our results indicate that surface and subsurface species create hydrated electrons in the bulk side. No signature of a surface-bound electron has been observed

An approach for elucidating dermal fibroblast dedifferentiation in amphibian limb regeneration

Urodele amphibians, Pleurodeles waltl and Ambystoma mexicanum, have organ-level regeneration capability, such as limb regeneration. Multipotent cells are induced by an endogenous mechanism in amphibian limb regeneration. It is well known that dermal fibroblasts receive regenerative signals and turn into multipotent cells, called blastema cells. However, the induction mechanism of the blastema cells from matured dermal cells was unknown. We previously found that BMP2, FGF2, and FGF8 (B2FF) could play sufficient roles in blastema induction in urodele amphibians. Here, we show that B2FF treatment can induce dermis-derived cells that can participate in multiple cell lineage in limb regeneration. We first established a newt dermis-derived cell line and confirmed that B2FF treatment on the newt cells provided plasticity in cellular differentiation in limb regeneration. To clarify the factors that can provide the plasticity in differentiation, we performed the interspecies comparative analysis between newt cells and mouse cells and found the Pde4b gene was upregulated by B2FF treatment only in the newt cells. Blocking PDE4B signaling by a chemical PDE4 inhibitor suppressed dermis-to-cartilage transformation and the mosaic knockout animals showed consistent results. Our results are a valuable insight into how dermal fibroblasts acquire multipotency during the early phase of limb regeneration via an endogenous program in amphibian limb regeneration

Influence of Nearby Plants and Artificial Structures on the Surface Air Temperature Statistics : An in-situ Measurement at Central Tokyo (Otemachi) throughout Years

In order to clarify the influence of obstacles on temperature measurement, two years\u27 continuous observation was made in the meteorological enclosure of the Japan Meteorological Agency in central Tokyo (Otemachi), by installing an extra thermometer at a spot that was surrounded by trees and was 20 m distant from the thermometer for operational observation. In the early afternoon of the warm season, the temperature at the spot surrounded by trees was found to be higher than the operational temperature. The temperature difference at 15JST was about 0.5 degrees Celsius on theaverage, and was correlated with daily solar radiation with a correlation coefficient of over 0.7 from March to September. On the other hand, difference of nighttime temperature was generally small, so that the monthly mean difference of daily mean temperatures was less than 0.1 degree Celsius for all the months of the year