Whole-genome analysis of human group A rotaviruses in 1980s Japan and evolutionary assessment of global Wa-like strains across half a century.

Historically, the Wa-like strains of human group A rotavirus (RVA) have been major causes of gastroenteritis. However, since the 2010s, the circulation of non-Wa-like strains has been increasingly reported, indicating a shift in the molecular epidemiology of RVA. Although understanding RVA evolution requires the analysis of both current and historical strains, comprehensive pre-1980's sequencing data are scarce globally. We determined the whole-genome sequences of representative strains from six RVA gastroenteritis outbreaks observed at an infant home in Sapporo, Japan, between 1981 and 1989. These outbreaks were mainly caused by G1 or G3 Wa-like strains, resembling strains from the United States in the 1970s-1980s and from Malawi in the 1990s. Phylogenetic analysis of these infant home strains, together with Wa-like strains collected worldwide from the 1970s to 2020, revealed a notable trend: pre-2010 strains diverged into multiple lineages in many genomic segments, whereas post-2010 strains tended to converge into a single lineage. However, Bayesian skyline plot indicated near-constant effective population sizes from the 1970s to 2020, and selection pressure analysis identified positive selection only at amino acid 75 of NSP2. These results suggest that evidence supporting the influence of rotavirus vaccines, introduced globally since 2006, on Wa-like RVA molecular evolution is lacking at present, and phylogenetic analysis may simply reflect natural fluctuations in RVA molecular evolution. Evaluating the long-term impact of RV vaccines on the molecular evolution of RVA requires sustained surveillance.

Effect of extracellular matrix fiber cross-linkage on cancer cell motility and surrounding matrix deformation.

Cancer incidence is increasing annually, and the invasion of cancer into the stroma significantly affects cancer metastasis. The stroma primarily comprises an abundant extracellular matrix (ECM) that interacts closely with cancer cells. Cancer cells use the ECM as a scaffold to migrate from a tumor via mechanical actions such as pushing and pulling the fibers. The purpose of this study is to clarify the effects of elastic modulus differences on cell migration behavior based on the same ECM fiber structure. We observe temporal changes in the morphology of cancer cells and the surrounding ECM to elucidate the relationship between changes in the mechanical properties of the ECM and the invasive behavior of cancer cells. We analyze the shape and migration distance of cancer cells and the displacement field of the ECM by varying the fiber elastic modulus but fixing the ECM density. Increasing the elastic modulus results in a protruding cell shape, which indicates the maximum displacement of the ECM around the cell. Additionally, differences in cell migration speed and dispersion based on the elastic modulus are observed. The behavior of cells with increasing elasticity is classified via cluster analysis. Owing to the chemical cross-linking of the fibers, some cells cannot deform the surrounding tissue. This is attributable to the gel state of the ECM and microscopic fluctuations in the fiber density around the cells. We successfully assessed the effect of changes in the ECM modulus on cell mortality and morphology to reveal the mechanism of cancer invasion.

Fabrication of multiwall carbon nanotube sheet based hydrogen sensor on a stacking multi-layer structure.

In this research, we propose a new simple method to fabricate hydrogen gas sensors by stacking multiwall carbon nanotube (MWCNT) sheets. MWCNT sheets offer a larger surface area and more CNT contact, which are key factors for gas sensing, because of their super-high alignment and end-to-end structure compared to traditional CNT film. Besides, MWCNT sheets can be directly drawn from spinnable CNT arrays on large scales. Therefore, this method is a potential answer for the mass production and commercialization of CNT-based sensors with high responsivity. By stacking layers of sheets in various arrangements, the microstructure and CNT interactions in the layers were changed and their influence on gas sensing investigated. It was observed that the sample with three layers of sheet and functionalized with 3 nm thick Pd showed the best gas sensing performance, with a response of 12.31% at 4% H2 and response time below 200 s.

Nanowire surface fastener fabrication on flexible substrate.

The market for wearable devices has increased considerably in recent years. In response to this demand, flexible electronic circuit technology has become more important. The conventional bonding technology in electronic assembly depends on high-temperature processes such as reflow soldering, which result in undesired thermal damages and residual stress at a bonding interface. In addition, it exhibits poor compatibility with bendable or stretchable device applications. Therefore, there is an urgent requirement to attach electronic parts on printed circuit boards with good mechanical and electrical properties at room temperature. Nanowire surface fasteners (NSFs) are candidates for resolving these problems. This paper describes the fabrication of an NSF on a flexible substrate, which can be used for room temperature conductive bonding. The template method is used for preparing high-density nanowire arrays. A Cu thin film is layered on the template as the flexible substrate. After etching the template, a Cu NSF is obtained on the Cu film substrate. In addition, the electrical and mechanical properties of the Cu NSF are studied under various fabrication conditions. The Cu NSF exhibits high shear adhesion strength (∼234 N cm-2) and low contact resistivity (2.2 × 10-4 Ω cm2).

Syntheses of prodrug-type 2'-O-methyldithiomethyl oligonucleotides modified at natural four nucleoside residues and their conversions into natural 2'-hydroxy oligonucleotides under reducing condition.

We previously reported that reducing-environment-responsive prodrug-type small interfering RNA (siRNA) bearing 2'-O-methyldithiomethyl (2'-O-MDTM) uridine exhibits efficient knockdown activity and nuclease resistance. In this report, we describe the preparation of 2'-O-MDTM oligonucleotides modified not only at uridine but also at adenosine, guanosine and cytidine residues by post-synthetic modification. Precursor oligonucleotides bearing 2'-O-(2,4,6-trimethoxybenzylthiomethyl) (2'-O-TMBTM) adenosine, guanosine, and cytidine were reacted with dimethyl(methylthio)sulfonium tetrafluoroborate to form 2'-O-MDTM oligonucleotides in the same manner as the oligonucleotide bearing 2'-O-TMBTM uridine. Furthermore, the oligonucleotides bearing 2'-O-MDTM adenosine, guanosine, and cytidine were efficiently converted into corresponding natural 2'-hydroxy oligonucleotides under the cytosol-mimetic reducing condition.

Decreased nuclear stiffness via FAK-ERK1/2 signaling is necessary for osteopontin-promoted migration of bone marrow-derived mesenchymal stem cells.

Migration of bone marrow-derived mesenchymal stem cells (BMSCs) plays an important role in many physiological and pathological settings, including wound healing. During the migration of BMSCs through interstitial tissues, the movement of the nucleus must be coordinated with the cytoskeletal dynamics, which in turn affects the cell migration efficiency. Our previous study indicated that osteopontin (OPN) significantly promotes the migration of rat BMSCs. However, the nuclear behaviors and involved molecular mechanisms in OPN-mediated BMSC migration are largely unclear. In the present study, using an atomic force microscope (AFM), we found that OPN could decrease the nuclear stiffness of BMSCs and reduce the expression of lamin A/C, which is the main determinant of nuclear stiffness. Increased lamin A/C expression attenuates BMSC migration by increasing nuclear stiffness. Decreased lamin A/C expression promotes BMSC migration by decreasing nuclear stiffness. Furthermore, OPN promotes BMSC migration by diminishing lamin A/C expression and decreasing nuclear stiffness via the FAK-ERK1/2 signaling pathway. This study provides strong evidence for the role of nuclear mechanics in BMSC migration as well as new insight into the molecular mechanisms of OPN-promoted BMSC migration.

Tenocyte proliferation and migration promoted by rat bone marrow mesenchymal stem cell-derived conditioned medium.

OBJECTIVES: To investigate the impact of secreted factors of rat bone marrow mesenchymal stem cells (MSCs) on the proliferation and migration of tenocytes and provide evidence for the development of MSC-based therapeutic methods of tendon injury. RESULTS: Rat bone marrow mesenchymal stem cell-derived conditioned medium (MSC-CM) promoted the proliferation of tenocytes within 24 h and decreased the percentage of tenocytes in G1 phase. MSC-CM activated the extracellular signal-regulated kinase1/2 (ERK1/2) signal molecules, while the ERK1/2 inhibitor PD98059 abrogated the MSC-CM-induced proliferation of tenocytes, decreased the fraction of tenocytes in the G1 phase and elevated p-ERK1/2 expression. Furthermore, MSC-CM promoted the migration of tenocytes within 6 h, enhanced the formation of filamentous actin (F-actin) and increased the cellular and nuclear stiffness of tenocytes. CONCLUSIONS: MSC-CM promotes tenocyte proliferation by changing cell cycle distribution via the ERK1/2 signaling pathway. MSC-CM-induced tenocyte migration was accompanied by cytoskeletal polymerization and increases in cellular and nuclear stiffness.

Development of a new co-culture system, the "separable-close co-culture system," to enhance stem-cell-to-chondrocyte differentiation.

OBJECTIVE: To develop a new co-culture system, the separable-close co-culture system, to replace the indirect co-culture system which analyzes cellular interactions between two groups of cells with each type being cultured separately and also the direct co-culture system where the two cell types are cultured together. RESULTS: The new system not only achieved effective cellular interactions but also allowed the effect that one group of cells has on another group of cells to be evaluated. We performed co-culturing of human bone marrow mesenchymal stem cells and human articular chondrocytes using the new system. The new system made it possible to assess separately the effects of one group of cells on the other cell type, as in the indirect co-culture system. Furthermore, the new system rivaled or surpassed other co-culture systems in terms of the chondrogenic gene expression. CONCLUSION: The new co-culture system is effective in terms of assessing gene expression in two cell types.

tLyP-1-conjugated Au-nanorod@SiO(2) core-shell nanoparticles for tumor-targeted drug delivery and photothermal therapy.

Mesoporous silica-coated Au nanorod (AuNR@SiO2) is one of the most important appealing nanomaterials for cancer therapy. The multifunctions of chemotherapy, photothermal therapy, and imaging of AuNR@SiO2 make it very useful for cancer therapy. In this study, AuNR@SiO2 was functionalized to deliver hydrophobic antitumor drug and to heat the targeted tumor with the energy of near-infrared (NIR). To carry out the function of targeting the tumor, tLyP-1, a kind of tumor homing and penetrating peptide, was engrafted to AuNR@SiO2. The fabricated AuNR@SiO2-tLyP-1 which was loaded with camptothecin (CPT) showed a robust, selective targeting and penetrating efficiency to Hela and MCF-7 cells and induced the death of these cells. When the micromasses of these AuNR@SiO2-tLyP-1 internalized cells were irradiated by NIR illumination, all the cells were killed instantaneously owing to the increased temperature caused by the surface plasma resonance (SPR) of the internalized AuNR@SiO2-tLyP-1. Moreover, the systematic toxicity of CPT-loaded AuNR@SiO2-tLyP-1 on human mesenchymal stem cells (hMSCs) was minimized, because the AuNR@SiO2-tLyP-1 selectively targeted and penetrated into the tumor cells, and little hydrophobic CPT was released into the culture medium or blood. This study indicates that the AuNR@SiO2-tLyP-1 drug delivery system (DDS) has great potential application for the chemo-photothermal cancer therapy.

Nanocarriers for drug-delivery systems using a ureido-derivatized polymer gatekeeper for temperature-controlled spatiotemporal on-off drug release.

Accidental chemotherapy extravasation exacerbates the side effects of anticancer drugs. Therefore, drug-delivery nanocarriers should be designed to avoid persistent drug release at off-target sites and promote burst drug release at on-target. Considering these requirements, poly(allylamine)-co-poly(allylurea) (PAU), a ureido-derivatized temperature responsive polymer with upper critical solution temperature (UCSTs), is an ideal material. This report describes the fabrication, characterization, and in vitro cellular toxicity of PAU polymer-grafted magnetic mesoporous silica nanoparticles as drug-delivery nanocarriers. A UCST of 43 °C and an ultranarrow transition temperature range of 39-43 °C was realized, ensuring that the nanocarriers suppressed undesirable leakage to below 10 % of the drug loading for 8 h in the absence of a thermal stimulus. A drug release burst of up to 75 % of the drug loading was achieved within 30 min after the stimulus, reducing the viability of the in vitro cancer cells to 12 %. Therefore, the ureido-derivatized polymer is one of the most suitable gatekeepers for drug-delivery nanocarriers.

Developments of real-time emittance monitors.

Under the upgrade program of an azimuthally varying field (AVF) cyclotron in progress at the Research Center for Nuclear Physics (RCNP), an emittance monitor is being developed to improve the beam injection efficiency from ion sources to the AVF cyclotron. In order to evaluate the quality of the beams extracted from ion sources quickly, we developed the Pepper-Pot type Emittance Monitor at the RCNP. After improving an analysis method for emittance estimation using LabVIEW, we achieved a measurement frequency of 4 Hz.

Functional characterization of the trigger factor protein PceT of tetrachloroethene-dechlorinating Desulfitobacterium hafniense Y51.

Desulfitobacterium hafniense strain Y51 dechlorinates tetrachloroethene to cis-1,2-dichloroethene (cis-DCE) via trichloroethene by the action of the PceA reductive dehalogenase encoded by pceA. The pceA gene constitutes a gene cluster with pceB, pceC, and pceT. However, the gene components, except for pceA, still remained to be characterized. In the present study, we characterized the function of PceT. PceT of strain Y51 showed a sequence homology with trigger factor proteins, although it is evolutionally distant from the well-characterized trigger factor protein of Escherichia coli. The PceT protein tagged with 6x histidine was expressed as a soluble form in E. coli. The recombinant PceT fusion protein exhibited peptidyl-proryl cis-trans isomerase activity toward the chromogenic peptide N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide. The PceT fusion protein also exhibited chaperon activity towards the chemically denatured citrate synthase. Immunoprecipitation analysis using antibodies raised against PceA and PceT demonstrated that PceT specifically binds to the precursor form of PceA with an N-terminal twin-arginine translocation (TAT) signal sequence. On the other hand, PceT failed to bind the mature form of PceA that lost the TAT signal sequence. This is the first report in dehalorespiring bacteria, indicating that PceT is responsible for the correct folding of the precursor PceA.

Local permittivity measurement of dielectric materials based on the non-contact force curve of microwave atomic force microscopy.

We report a non-contact and quantitative method to measure the local permittivity of dielectric materials with a nanometer-scale spatial resolution. A theoretical model based on near-field approximation was developed to describe the effect of a microwave on the interaction between a probe and a sample. Under the non-contact mode, we successfully measured the force curves of Si, Al2O3, Ge, and ZrO2 using microwave atomic force microscopy and observed the variation in the force caused by the microwave. According to the established theoretical model, a quantitative non-contact evaluation of the local permittivity of dielectric materials was performed.

A 64-pin Nanowire Surface Fastener Like a Ball Grid Array Applied for Room-temperature Electrical Bonding.

Surface-mount techniques primarily depend on soldering. However, soldering techniques have encountered some challenges in recent years. These challenges include rare metal recycling, thermal problems, and Pb toxicity. We recently developed a metallic nanowire surface fastener (NSF) to resolve the abovementioned problems. This fastener can be used to connect electronic components on a substrate at room temperature using the van der Waals force between each nanowire. This study demonstrates a 64-pin NSF that behaves like a ball grid array (BGA) for application to actual electronic devices. The adhesion strength and electrical properties of the NSF were investigated by adjusting the nanowire parameters, such as diameter, length, density (number per area), preload, and shape. The shape control of the nanowires greatly contributed to the improvement of the properties. A maximum adhesion strength of 16.4 N/cm2 was achieved using a bent, hook-like NSF. This strength was 4-5 times the value of the straight NSF. The contact resistivity was 2.98 × 10-2 Ω∙cm2. The NSF fabricated through the simple template method showed the room temperature bonding ability and adaptability to a highly ordered electrode like the BGA.

The optimal mechanical condition in stem cell-to-tenocyte differentiation determined with the homogeneous strain distributions and the cellular orientation control.

In tendon tissue engineering, mechanical stimulus-induced differentiation is one of the most attractive techniques for stem cell-to-tenocyte differentiation in terms of cost, safety and simplicity. However, the most effective strain amplitude for differentiation using cyclic stretching remains unknown. Existing studies have not constrained cell reorientation behavior during cyclic stretching, resulting in uncertainty regarding the loads experienced by cells. In addition, strain distribution homogeneity of the culture membrane is important. Here, we improved the strain distribution uniformity of the membrane and employed a microgrooved membrane to suppress cell reorientation. Then we evaluated the most effective strain amplitude (0, 2, 4, 5, 6, or 8%) for the differentiation of mesenchymal stem cells into tenocytes by measuring mRNA expression levels. The maximum expression of all tenogenic markers was observed at a 5% strain. These results contribute to tendon tissue engineering by clarifying the most effective strain amplitude during tenogenic differentiation induction using cyclic stretching.

Synthesis of a single-crystal Fe2O3 nanowire array based on stress-induced atomic diffusion used for solar water splitting.

In this study, we successfully fabricated a single-crystal Fe2O3 nanowire array based on stress-induced atomic diffusion and used this array as the photoelectrode for solar water splitting. With the surface polishing treatment on the sample surface, the density of the Fe2O3 nanowire array reached up to 28.75 wire µm-2 when heated for 90 min at 600°C. The photocurrent density of the optimized sample was 0.9 mA cm-2 at 1.23 V versus a reversible hydrogen electrode in a three-electrode system under AM 1.5 G illumination. The incident photon-to-electron conversion efficiency was 6.8% at 400 nm.

Optimization of differentiation time of mesenchymal-stem-cell to tenocyte under a cyclic stretching with a microgrooved culture membrane and selected measurement cells.

PURPOSE: There is a need for efficient stem cell-to-tenocyte differentiation techniques for tendon tissue engineering. More than 1 week is required for tenogenic differentiation with chemical stimuli, including co-culturing. Research has begun to examine the utility of mechanical stimuli, which reduces the differentiation time to several days. However, the precise length of time required to differentiate human bone marrow-derived mesenchymal stem cells (hBMSCs) into tenocytes has not been clarified. Understanding the precise time required is important for future tissue engineering projects. Therefore, in this study, a method was developed to more precisely determine the length of time required to differentiate hBMSCs into tenocytes with cyclic stretching stimulus. METHODS: First, it had to be determined how stretching stimulation affected the cells. Microgrooved culture membranes were used to suppress cell orientation behavior. Then, only cells oriented parallel to the microgrooves were selected and evaluated for protein synthesis levels for differentiation. RESULTS: The results revealed that growing cells on the microgrooved membrane and selecting optimally-oriented cells for measurement improved the accuracy of the differentiation evaluation, and that hBMSCs differentiated into tenocytes in approximately 10 h. CONCLUSIONS: The differentiation time corresponded to the time required for cellular cytoskeleton reorganization and cellular morphology alterations. This suggests that cells, when subjected to mechanical stimulus, secrete mRNAs and proteins for both cytoskeleton reorganization and differentiation.

Effect of Electropulsing Treatment on the Fatigue Crack Growth Behavior of Copper.

Crack propagation was quantitatively evaluated to investigate the effect of electropulsing treatment (EPT) on fatigue crack growth of copper specimens. Varying fatigue cycles were obtained under six different load levels. The crack lengths were measured under two load levels to examine the effect of cyclic stress. The microhardness was measured around the vicinity of the crack tip. Furthermore, the fracture surface was observed by scanning electron microscopy. Results show that EPT with electric current density of 150 A/mm² enhances the high-cycle fatigue life, and the effect tends to increase with the decrease in cyclic stress. Vickers microhardness (HV) near the crack tip decreases to normal levels after treatment, and the approaching cracks on two sides can be observed. Local annealing and recrystallization occur around the fatigue crack tip. Accordingly, crack propagation can be delayed, and fatigue life can be prolonged by EPT.

Chromatin organization regulated by EZH2-mediated H3K27me3 is required for OPN-induced migration of bone marrow-derived mesenchymal stem cells.

Osteopontin (OPN) is a chemokine-like extracellular matrix-associated protein involved in the migration of bone marrow-derived mesenchymal stem cells (BMSCs). An increasing number of studies have found that chromatin organization may affect cellular migration. However, whether OPN regulates chromatin organization is not understood, nor are the underlying molecular mechanisms. In this study, we investigated the link between chromatin organization and BMSC migration and demonstrated that OPN-mediated BMSC migration leads to elevated levels of heterochromatin marker histone H3 lysine 27 trimethylation (H3K27me3) through the methyltransferase EZH2. The expression of EZH2 reorganizes the chromatin structure of BMSCs. Pharmacological inhibition or depletion of EZH2 blocks BMSC migration. Moreover, using an atomic force microscope (AFM), we found that chromatin decondensation alters the mechanical properties of the nucleus. In addition, inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) signals represses OPN-promoted chromatin condensation and cell migration. Thus, our results identify a mechanism by which ERK1/2 signalling drives specific chromatin modifications in BMSCs, which alters chromatin organization and thereby enables OPN-mediated BMSC migration.

Construction of tendon replacement tissue based on collagen sponge and mesenchymal stem cells by coupled mechano-chemical induction and evaluation of its tendon repair abilities.

Tissue engineering is an ideal therapeutic strategy for the development of functional tendon replacement tissue for tendon repair in the clinic. Currently, the synergistic roles of mechano-chemical factors and the mechanisms involved in tendon repair and regeneration are not fully understood. In this study, we developed a three-dimensional (3D) culture system based on a silicone chamber and collagen sponge scaffold that can deliver cyclic mechanical stretch and biochemical stimulation to bone marrow-derived mesenchymal stem cells (BMSCs) seeded on the scaffold. We found that the combined stimulation of cyclic stretch and transforming growth factor beta 1 (TGF-ß1) treatment not only increased cell viability but also synergistically promoted the differentiation of BMSCs into tenocytes in a 3D culture environment. Meanwhile, the combined stimulation increased the Young's modulus of the BMSC-collagen sponge constructs by reducing the porosity of the scaffold compared to the non-treated constructs. Furthermore, a rat Achilles tendon in situ repair experiment showed that enhanced tendon regeneration was achieved using the BMSC-collagen sponge construct combined with cyclic stretch and TGF-ß1, as confirmed by Achilles functional index (AFI) measurement, morphological observation, histological analysis, and mechanical testing. These results suggest that this approach could offer a practical benefit in tendon healing and future tendon tissue engineering. STATEMENT OF SIGNIFICANCE: This study aims to disclose the crucial roles of the coupled induction by mechano-chemical stimulation in tendon tissue engineering and clarifies their collaborative control mechanisms. We developed a three-dimensional (3D) culture system based on a silicone chamber and collagen sponge scaffold that could deliver cyclic mechanical stretch and biochemical stimulation to bone marrow-derived mesenchymal stem cells (BMSCs). We found that the combined stimulation of cyclic stretch and transforming growth factor beta 1 (TGF-ß1) could result in an improvement of tissue-engineered construct for enhancing tendon healing. These results suggest that this approach could offer a practical benefit in tendon healing and future tendon tissue engineering.