Publications by authors named "Ryuta Arai"

In shallow subduction zones, fluid behavior impacts various geodynamic processes capable of regulating slip behaviors and forming mud volcanoes. However, evidence of structures that control the fluid transfer within an overriding plate is limited and the physical properties at the source faults of slow earthquakes are poorly understood. Here we present high-resolution seismic velocity models and reflection images of the Hyuga-nada area, Japan, where the Kyushu-Palau ridge subducts.

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Article Synopsis
  • Recurring slow slip events occur at subduction zones due to fluid overpressures but are not universally observed; the relationship between slow slip and hydrogeology remains unclear.
  • Recent studies at the Hikurangi margin have identified a substantial fluid reservoir within the hydrated volcanic upper crust of the subducting Hikurangi Plateau.
  • The volcaniclastic-rich upper crust retains significant fluid content during subduction, suggesting it plays a crucial role in supplying water that may lead to overpressures along megathrust faults, potentially leading to increased occurrences of shallow slow slip.
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Background/aim: Although smoking history is predictive of poor pulmonary metastasis-free survival (PMFS) in patients with epithelial tumors, the impact of smoking history on PMFS in those with soft-tissue sarcoma (STS) is not known.

Patients And Methods: Patients undergoing treatment for STS at our institutes between 2008 and 2017 were enrolled. Patients were excluded if they had metastatic lesion, or had a histopathological classification demonstrating small round-cell sarcoma.

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A ship-based seismic survey was conducted close to a fiber-optic submarine cable, and 50 km-long distributed acoustic sensing (DAS) recordings with air-gun shots were obtained for the first time. We examine the acquired DAS dataset together with the co-located hydrophones to investigate the detection capability of underwater acoustic (hydroacoustic) signals. Here, we show the hydroacoustic signals identified by the DAS measurement characterizing in frequency-time space.

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Background: Hepatic metastasis of soft tissue sarcoma is rare compared to lung metastasis, and the literature is scarce. We examined the risk of hepatic metastasis according to the site of occurrence and histological type.

Methods: From a Hospital-based Cancer Registry, 658 patients registered between 2007 and 2017 with soft tissue sarcomas were evaluated.

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Breast cancer is one of the most prevalent malignancies in women, and approximately 75-80% of patients with advanced breast cancer develop bone metastasis. Expression of the cancer-associated carbohydrate antigen sialyl-Tn (STn) in breast cancer is associated with a poor prognosis; however, involvement of STn in the development of metastatic bone lesions remains unclear. We investigated whether STn expression on breast cancer cells influences intraosseous tumor growth and bone response in mice models of skeletal colonization.

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Background: Good outcomes have been reported in revision total hip replacement with massive segmental defects using impaction bone grafting with circumferential metal meshes. However, the morphology of defects that require a mesh is poorly defined. The purpose of this study was to evaluate the effects of a variety of segmental defects on load transmission to the proximal femur under both axial and rotational loads.

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Background: The incidence of bilateral corticosteroid-induced osteonecrosis of the femoral head (ONFH) is high. Although the precise mechanism of corticosteroid-induced ONFH development is unclear, hepatic enzyme abnormalities such as low activity of hepatic cytochrome P450 3A could be one cause. Herein, we report the case of a patient who developed ONFH in the contralateral hip after the dose of corticosteroids for idiopathic thrombocytopenic purpura was increased.

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Despite good clinical outcomes associated with curved intertrochanteric varus osteotomy for the treatment of osteonecrosis of the femoral head, post-operative leg-length discrepancy is frequently reported and might reduce patient satisfaction. Although previous report showed that varus angulation affected post-operative leg-length discrepancy, sufficient varus angulation is the most important factor for obtaining a lateral intact portion. Therefore, to ensure better postoperative outcomes, detection of other parameters associated with leg shortening may prove useful.

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Background: The definitive treatment of borderline-to-mild dysplasia remains controversial. A more comprehensive understanding of the etiology of osteoarthritis (OA) and clarification of any possible association between borderline-to-mild dysplasia and the pathogenesis of OA are essential.

Questions/purposes: (1) Does the distribution of acetabular subchondral bone density increase according to dysplasia severity? (2) Is there an association between borderline-to-mild dysplasia and OA pathogenesis?

Methods: We evaluated bilateral hips of patients with developmental dysplasia of the hip who underwent eccentric rotational acetabular osteotomy (ERAO) for inclusion in the dysplasia group and contralateral hips of patients with unilateral idiopathic osteonecrosis of the femoral head (ONFH) who underwent curved intertrochanteric varus osteotomy (CVO) for the control group.

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The interactions of the lithospheric plates that form the Earth's outer shell provide much of the evidentiary basis for modern plate tectonic theory. Seismic discontinuities in the lithosphere arising from mantle convection and plate motion provide constraints on the physical and chemical properties of the mantle that contribute to the processes of formation and evolution of tectonic plates. Seismological studies during the past two decades have detected seismic discontinuities within the oceanic lithosphere in addition to that at the lithosphere-asthenosphere boundary (LAB).

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Unlabelled: Osteolysis is a serious postoperative complication of total joint arthroplasty that leads to aseptic loosening and surgical revision. Osteolysis is a chronic destructive process that occurs when host macrophages recognize implant particles and release inflammatory mediators that increase bone-resorbing osteoclastic activity and attenuate bone-formation osteoblastic activity. Although much progress has been made in understanding the molecular responses of macrophages to implant particles, the pathways/signals that initiate osteolysis remain poorly characterized.

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Background: Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by renal phosphate wasting, hypophosphatemia, reduction of 1,25-dihydroxyl vitamin D, and bone calcification disorders. Tumors associated with TIO are typically phosphaturic mesenchymal tumors that are bone and soft tissue origin and often present as a solitary tumor. The high production of fibroblast growth factor 23 (FGF23) by the tumor is believed to be the causative factor responsible for the impaired renal tubular phosphate reabsorption, hypophosphatemia and osteomalacia.

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Background: Collapse of the femoral head associated with nontraumatic osteonecrosis (NOFH) is one of the most common causes of disability in young adult patients. Excessive bone resorption by osteoclast coincident with the suppression of osteogenesis are believed to be responsible for collapse progression. Alendronate that inhibits bone resorption by inducing osteoclast apoptosis has been traditionally used for treating NOFH; however, several reports documented serious complications by the use of this drug.

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Purpose: Eccentric rotational acetabular osteotomy (ERAO) is a modification of rotational acetabular osteotomy (RAO); it has been reported that ERAO allows the femoral head to translate medially and distally. However, no study has compared femoral head translation following RAO or ERAO. The purpose of this study was to compare immediate postoperative translation of the femoral head after RAO and ERAO in comparison with the preoperative position by radiological methods.

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It has been recognized that even weakly coupled subduction zones may cause large interplate earthquakes leading to destructive tsunamis. The Ryukyu Trench is one of the best fields to study this phenomenon, since various slow earthquakes and tsunamis have occurred; yet the fault structure and seismic activity there are poorly constrained. Here we present seismological evidence from marine observation for megathrust faults and low-frequency earthquakes (LFEs).

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Synovial sarcoma is an obstinate, high-grade malignancy because of its modest responses to radiotherapy and chemotherapy; the identification of effective therapeutics for this sarcoma is therefore necessary. Inhibition of Src family kinases (SFKs) suppresses the proliferation of synovial sarcoma cells in vitro, as we have previously reported. In this study, to validate the efficacy of Src inhibition in vivo, we employed SU6656, which was originally identified as a specific SFK inhibitor.

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