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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

Directed Differentiation and Paracrine Mechanisms of Mesenchymal Stem Cells: Potential Implications for Tendon Repair and Regeneration.

BACKGROUND: Tendon is composed of connective tissue, is able to retract with high tensile force, and plays a significant role in musculoskeletal motion. However, inappropriate physical training or accidents often result in tendon injuries. So far, the functional healing of injured tendon is still a great challenge in orthopedics. Mesenchymal stem cells (MSCs) are multilineage cells with the ability to self-renew and differentiate into a variety of cell types, including tenocytes. The plasticity of MSCs gives rise to the chance of improved healing of injured tendons and even tissue-engineered tendons. Recently, more and more works have shown that the paracrine mechanisms of MSCs also play a critical role in driving the tendon repair process. OBJECTIVE: The purpose of this review is to summarize the current knowledge of the induction of tenogenic differentiation of MSCs by mechanical, chemical and mechanochemical stimulations. The role of paracrine mechanisms of MSCs during the repair of injured tendons is also discussed. CONCLUSION: The multilineage potential and the paracrine effects of MSCs create the chance for improved healing of injured tendons and even tissue-engineered tendons. The understanding of the regulation of the two different repair mechanisms (directed differentiation and paracrine) of MSCs has important implications for tendon repair and regeneration.

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.

Usefulness of measuring acetabular anterior coverage using a tomosynthesis imaging system.

PURPOSE: The purpose of this study was to compare the usefulness of measuring acetabular anterior coverage by tomosynthesis and false profile (FP) radiography. METHODS: 70 hips in 35 patients who were diagnosed with early stage osteoarthritis of the hip, and 60 hips from 30 healthy volunteers were analysed. Plain FP radiographs were taken, and vertical-centre-anterior margin (FP-VCA) angles were measured. Acetabular anterior coverage was measured in the natural standing position using a tomosynthesis imaging system in the sagittal plane. As with FP radiography, we measured vertical-centre-anterior margin (TS-VCA) angles. RESULTS: The median values of the FP-VCA angle, and TS-VCA angle were 43.8°, 54.4°, respectively. The TS-VCA angle was significantly larger than the FP-VCA angle. For FP radiographs, the intraobserver intraclass correlation coefficient (ICC) was 0.68, and the interobserver ICC was 0.79. For tomosynthesis sagittal images, the intraobserver ICC was 0.85, and the interobserver ICC was 0.92. There was a strong positive correlation between the TS-VCA angle and the FP-VCA angle. When the FP-VCA angle was 25°, the TS-VCA angle was 35° in regression analysis. CONCLUSIONS: Measuring acetabular anterior coverage using sagittal plane tomosynthesis correlates well with FP radiography. Regardless of the presence of acetabular deformities, tomosynthesis demonstrated high reproducibility, simple posture setting, low effective doses, and high versatility. A cut-off value of 35° was useful for the detection of developmental dysplasia of the hip joint using the TS-VCA angle.

Mesenchymal stem cell-induced 3D displacement field of cell-adhesion matrices with differing elasticities.

Cells maintain homeostasis and perform various functions by interacting mechanically with a cell-adhesive matrix. Regarding cellular differentiation, it has been found that matrix elasticity can determine the differentiation lineage of mesenchymal stem cells (MSCs). Direct quantitative measurements of the mechanical interaction between MSCs and matrix for differentiation, however, have yet to be reported. Herein, the displacement field of the cell-adhesive matrix was observed quantitatively using a digital volume correlation (DVC) method. Maximum displacement and cellular traction stress were analyzed when the MSC differentiated into a neuron-like cell or an osteoblast-like cell on a soft or hard elastic matrix, respectively. The function of non-muscle myosin II (NMM II), which plays an important role in intracellular cytoskeletal dynamics, was investigated during cellular differentiation. The mechanical interaction (maximum displacement and subjected area of the matrix) between the cell and matrix was dependent on matrix elasticity. It has also been shown that the mechanical interaction between the intracellular cytoskeleton and cell-adhesion matrix is indispensable for cellular differentiation. This work provides the first quantitative visualization of the mechanical interaction between MSCs and the cell-adhesion matrix for differentiation.