生体分子の簡易検出を目指した凝集誘起発光色素ラベル化プローブの開発と検出メカニズムの解明

バイオイメージングやバイオマーカーの検出による診断には蛍光色素が汎用されるが、そうした手法にはいくつかの問題点がある。その中でも、濃度消光の問題は一般の蛍光色素においては本質的なデメリットであり、このことが検出感度の壁となっている場合が多い。そこで、本研究では、濃度消光とは逆に凝集によって蛍光強度が劇的に増大する凝集誘起発光（AIE）色素を用いて疾患の診断を行う手法の開発を行い、その検出メカニズムを明らかにすることを目的とした。ターゲットとする疾患として、罹患者数が多く社会的影響が大きいガンとアルツハイマー病（AD）を選び、それぞれのバイオマーカーと考えられるテロメア鎖およびアミロイドβ（A）の検出を行った。テロメア鎖に対するプローブとして、AIE色素で修飾した相補鎖DNAまたはPNAを用いたところ、どちらのプローブでも高い感度でテロメア鎖の定量が可能であることが示された。しかし、プローブがDNA の場合にはテロメア量に比例して蛍光強度が増加するのに対しPNAをプローブとした場合には、逆に濃度依存的に蛍光強度が弱くなった。これは、PNAの疎水性によりプローブ自身が凝集することで生じた強い蛍光が、二重鎖形成とともに分散して消光されたためであることを明らかにした。また、DNAプローブを用いた結果の考察から、AIE色素の周辺に分子運動を阻害するダングリングエンドまたは二重鎖が存在することが、蛍光増大の要件であることが示唆された。次に、ADのマーカーであるAの検出を行った。プローブとして、アミロイド繊維化促進ペプチド（AFPP）にAIE色素を結合させた化合物（AIE-AFPP）を用いた。AIE-AFPPはAFPP自身と同様にAの繊維化を促進するとともに、Aと共凝集することで濃度依存的にAIEの蛍光増大が観測され、短時間で容易にAの定量が可能であることが示された。この手法によるAの検出限界は4.2 nMであり、この値はELISAには及ばないが、プローブ合成およびassayの簡便性や、測定者に高いスキルを要求しない点において優れた手法である。本研究の結果は、AIE色素をシグナル発信部位としてもつプローブを用いることで、生体分子を高感度かつ簡便に定量可能であることを示している。また、本研究で明らかにされた蛍光増大のメカニズムは、ターゲットにあわせたプローブの分子設計と、安価・簡便・高感度・ハイスループットな検出システムの構築のための指針を与えると考えられる。甲南大学平成27年(2015年度

Oxygen uptake, heart rate, perceived exertion, and integrated electromyogram of the lower and upper extremities during level and Nordic walking on a treadmill

The purpose of this study was to characterize responses in oxygen uptake ( [Formula: see text]), heart rate (HR), perceived exertion (OMNI scale) and integrated electromyogram (iEMG) readings during incremental Nordic walking (NW) and level walking (LW) on a treadmill. Ten healthy adults (four men, six women), who regularly engaged in physical activity in their daily lives, were enrolled in the study. All subjects were familiar with NW. Each subject began walking at 60 m/min for 3 minutes, with incremental increases of 10 m/min every 2 minutes up to 120 m/min [Formula: see text] , [Formula: see text] and HR were measured every 30 seconds, and the OMNI scale was used during the final 15 seconds of each exercise. EMG readings were recorded from the triceps brachii, vastus lateralis, biceps femoris, gastrocnemius, and tibialis anterior muscles. [Formula: see text] was significantly higher during NW than during LW, with the exception of the speed of 70 m/min (P < 0.01). [Formula: see text] and HR were higher during NW than LW at all walking speeds (P < 0.05 to 0.001). OMNI scale of the upper extremities was significantly higher during NW than during LW at all speeds (P < 0.05). Furthermore, the iEMG reading for the VL was lower during NW than during LW at all walking speeds, while the iEMG reading for the BF and GA muscles were significantly lower during NW than LW at some speeds. These data suggest that the use of poles in NW attenuates muscle activity in the lower extremities during the stance and push-off phases, and decreases that of the lower extremities and increase energy expenditure of the upper body and respiratory system at certain walking speeds

Strengthening of Mg-based long-period stacking ordered (LPSO) phase with deformation kink bands

The mechanical properties of the Mg-based LPSO-phase are expected to be strongly affected by the microstructure due to its anisotropic crystal structure. However, the fine details have not been sufficiently understood yet. This study first clarified the detailed microstructural factors that govern the strength of the LPSO-phase by examining alloys with microstructures that were significantly varied via directional solidification and extrusion processes. Refining the microstructure is significantly effective for strengthening LPSO-phase alloys. The yield stress of LPSO-phase alloys with random texture was previously reported to be increased by reducing the “length” of plate-like LPSO-phase grains. In addition, it was found in this study that the formation stress in the deformation kink band, which is a unique deformation mode in an LPSO-phase alloy, can be increased by decreasing the “thickness” of the grains. Furthermore, the study used directionally solidified crystals provided direct evidence that the introduction of the deformation kink band effectively increases the yield stress and work-hardening rate of alloys by hindering the motion of basal dislocations. This “kink-band strengthening” was found to have considerable temperature dependence. The strengthening is significant at or below 200 °C, but the effect gradually decreases above 300 °C and is accompanied by the operation of non-basal slip. The results quantitatively clarified that kink-band strengthening is one predominant reason why the LPSO-phase extruded alloy exhibits an unusually high yield stress at any loading orientation.Hagihara K., Yamasaki M., Kawamura Y., et al. Strengthening of Mg-based long-period stacking ordered (LPSO) phase with deformation kink bands. Materials Science and Engineering A, 763, 138163. https://doi.org/10.1016/j.msea.2019.138163

Development of a frequency-detuned interferometer as a prototype experiment for next-generation gravitational-wave detectors

We report on our prototype experiment that uses a 4-m detuned resonant sideband extraction interferometer with suspended mirrors, which has almost the same configuration as the next-generation, gravitational-wave detectors. We have developed a new control scheme and have succeeded in the operation of such an interferometer with suspended mirrors for the first time ever as far as we know. We believe that this is the first such instrument that can see the radiation pressure signal enhancement, which can improve the sensitivity of next-generation gravitational-wave detectors

Surprising increase in yield stress of Mg single crystal using long-period stacking ordered nanoplates

Mg–Zn–Y ternary alloys containing the long-period stacking ordered (LPSO) phase exhibit superior mechanical properties. This is believed to be originating from the LPSO phase acting as the strengthening phase. However, we first clarify that the mechanical properties of the matrix Mg solid solution in the Mg/LPSO two-phase alloy are significantly different from those of pure Mg. The yield stress of a Mg99.2Zn0.2Y0.6 single crystal (matrix Mg solid solution) is almost the same as that of an LPSO single-phase alloy. This is ascribed to the formation of thin stacking-fault-like defects, named “LPSO nanoplate”. In Mg99.2Zn0.2Y0.6, kink-band formation is induced in the same manner as that in the LPSO phase in deformation, resulting in high strength accompanied with increased ductility. Our results suggest that the strengthening mechanism of the Mg/LPSO two-phase alloy must be reconsidered depending on the microstructure. Furthermore, the results suggest that new ultrahigh-strength Mg alloys, which have much lower Zn and Y contents but the mechanical properties are comparable or superior than the present Mg/LPSO two-phase alloys, are expected to be developed via the appropriate control of LPSO nanoplate microstructures.Hagihara K., Ueyama R., Yamasaki M., et al. Surprising increase in yield stress of Mg single crystal using long-period stacking ordered nanoplates. Acta Materialia, 209, 116797. https://doi.org/10.1016/j.actamat.2021.116797

Strengthening mechanisms acting in extruded Mg-based long-period stacking ordered (LPSO)-phase alloys

The unusual increase in the strength by extrusion is a unique feature of recently developed Mg alloys containing the LPSO phase. In this study, we first elucidated the detailed mechanisms that induce this drastic strengthening. The dependencies of the deformation behavior of a Mg88Zn4Y7 extruded alloy, which contains ∼86-vol% LPSO phase, on the temperature, loading orientation, and extrusion ratio were examined. It was found that the yield stress of the alloy is drastically increased by extrusion, but the magnitude of the increase in the yield stress is significantly different depending on the loading orientation. That is, the strengthening of the LPSO phase by extrusion shows a strong anisotropy. By the detailed analyses, this was clarified to be derived from the variation in the deformation mechanisms depending on the loading orientation and extrusion ratio. Basal slip was found to govern the deformation behavior when the loading axis was inclined at a 45° to the extrusion direction, while the predominant deformation mechanism varies from basal slip to the formation of deformation kink bands as the extrusion ratio increased when the loading axis was parallel to the extrusion direction. Moreover, it was clarified in this study that the introduction of a deformation-kink-band boundary during extrusion effectively acts as a strong obstacle to basal slip. That is, “the kink band strengthening” was first quantitatively elucidated, which contributes to the drastic increase in the yield stress of the extruded LPSO-phase alloys in the wide temperature range below 400 °C.Hagihara K., Li Z., Yamasaki M., et al. Strengthening mechanisms acting in extruded Mg-based long-period stacking ordered (LPSO)-phase alloys. Acta Materialia, 163, 226. https://doi.org/10.1016/j.actamat.2018.10.016

Oberlin partial ulnar nerve transfer for restoration in obstetric brachial plexus palsy of a newborn: case report

An 8 month old male infant with Erb's birth palsy was treated with two peripheral nerve transfers. Except for rapid motor reinnervations, elbow flexion was obtained by an Oberlin's partial ulnar nerve transfer, while shoulder abduction was restored by an accessory-to-suprascapular nerve transfer. The initial contraction of the biceps muscle occurred two months after surgery. Forty months after surgery, elbow flexion reached M5 without functional loss of the ulnar nerve. This case demonstrates an excellent result of an Oberlin's nerve transfer for restoration of flexion of the elbow joint in Erb's birth palsy. However, at this time partial ulnar nerve transfer for Erb's birth palsy is an optional procedure; a larger number of cases will need to be studied for it to be widely accepted as a standard procedure for Erb's palsy at birth

Strain-rate dependence of deformation behavior of LPSO-phases

This is the first report clarifying the influence of the strain rate on the deformation behavior of Mg-based long-period stacking ordered (LPSO) phases with 14H, 18R, and 10H structures. The flow stress by basal slip showed a weakly positive or negligible strain-rate dependence, while the flow stress accompanied by the formation of deformation kink bands showed a unique negative strain-rate dependence. These results give the first experimental evidence on the recent proposal that Zn and Y atoms segregate at the kink band boundaries and hinder their migration, from the viewpoint of the mechanical properties.Hagihara K., Li Z., Yamasaki M., et al. Strain-rate dependence of deformation behavior of LPSO-phases. Materials Letters 214, 119 (2018); https://doi.org/https://doi.org/10.1016/j.matlet.2017.11.117