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174 result(s) for "Arai, Yosuke"
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Visualization of the strain-induced topological phase transition in a quasi-one-dimensional superconductor TaSe3
Control of the phase transition from topological to normal insulators can allow for an on/off switching of spin current. While topological phase transitions have been realized by elemental substitution in semiconducting alloys, such an approach requires preparation of materials with various compositions. Thus it is quite far from a feasible device application, which demands a reversible operation. Here we use angle-resolved photoemission spectroscopy and spin- and angle-resolved photoemission spectroscopy to visualize the strain-driven band-structure evolution of the quasi-one-dimensional superconductor TaSe 3 . We demonstrate that it undergoes reversible strain-induced topological phase transitions from a strong topological insulator phase with spin-polarized, quasi-one-dimensional topological surface states, to topologically trivial semimetal and band insulating phases. The quasi-one-dimensional superconductor TaSe 3 provides a suitable platform for engineering the topological spintronics, for example as an on/off switch for a spin current that is robust against impurity scattering. Angle-resolved photoemission spectroscopy is used to track the evolution of the electronic band structure of TaSe 3 across a strain-driven topological phase transition.
Testing electron–phonon coupling for the superconductivity in kagome metal CsV3Sb5
In crystalline materials, electron-phonon coupling (EPC) is a ubiquitous many-body interaction that drives conventional Bardeen-Cooper-Schrieffer superconductivity. Recently, in a new kagome metal CsV 3 Sb 5 , superconductivity that possibly intertwines with time-reversal and spatial symmetry-breaking orders is observed. Density functional theory calculations predicted weak EPC strength, λ, supporting an unconventional pairing mechanism in CsV 3 Sb 5 . However, experimental determination of λ is still missing, hindering a microscopic understanding of the intertwined ground state of CsV 3 Sb 5 . Here, using 7-eV laser-based angle-resolved photoemission spectroscopy and Eliashberg function analysis, we determine an intermediate λ=0.45–0.6 at T  = 6 K for both Sb 5 p and V 3 d electronic bands, which can support a conventional superconducting transition temperature on the same magnitude of experimental value in CsV 3 Sb 5 . Remarkably, the EPC on the V 3 d -band enhances to λ~0.75 as the superconducting transition temperature elevated to 4.4 K in Cs(V 0.93 Nb 0.07 ) 3 Sb 5 . Our results provide an important clue to understand the pairing mechanism in the kagome superconductor CsV 3 Sb 5 . Electron-phonon coupling is thought to be too weak to be responsible for the superconducting Cooper pairing of the kagome metals AV 3 Sb 5 , but an experimental measurement is lacking. Here, the authors use ARPES measurements to find that electron-phonon coupling in CsV 3 Sb 5 is strong enough to support the experimental superconducting transition.
Quantitative measures of vortex veins in the posterior pole in eyes with pachychoroid spectrum diseases
Pachychoroid spectrum diseases have attracted increasing attention, though their pathophysiology has yet to be fully elucidated. In this study, we assessed the vascular diameters of vortex veins in pachychoroid spectrum diseases such as central serous chorioretinopathy (CSC), pachychoroid neovasculopathy without polypoidal lesions (PNV), and pachychoroid neovasculopathy with polypoidal lesions (polypoidal choroidal vasculopathy: PCV). In a retrospective case series of 94 eyes with CSC, 60 eyes with PNV and 57 with PCV, we binarized en face optical coherence tomography (OCT) images of choroidal vortex veins and analyzed the mean diameter of vortex veins. The presence of anastomosis between the superior and inferior vortex veins and central choroidal thickness (CCT) were also evaluated using OCT images. CSC showed significantly larger mean diameter of vortex veins than PCV (P < 0.05). Anastomosis between superior and inferior vortex veins was observed in over 90% of eyes with each pachychoroid spectrum disease. The patients with CSC were the youngest, followed by PNV patients, and then patients with PCV. The largest CCT values were observed in CSC eyes, followed by PNV eyes, and then PCV eyes. CCT correlated with the mean diameter of vortex veins (rs = 0.51, P < 0.01). These findings suggest that congestion of vortex veins might show gradual amelioration corresponding to the development of anastomosis between the superior and inferior vortex veins during the course of progression of pachychoroid spectrum diseases. Moreover, the mean diameter of vortex veins can be used as a parameter indicating choroidal congestion.
Variation of vortex veins at the horizontal watershed in normal eyes
PurposeTo assess the vascular pattern of choroidal vortex veins at the horizontal watershed zone in normal eyes using optical coherence tomography (OCT).MethodsWe retrospectively studied 207 normal eyes of 207 patients whose fellow eyes were diagnosed with unilateral retinal diseases without choroidal involvement. Venous anastomosis between the superior and inferior vortex veins and deviation of the horizontal watershed zone were evaluated using 12 × 12-mm en face OCT images. Central choroidal thickness (CCT) was measured on B-mode OCT images.ResultsVortex vein anastomosis was observed in 92 eyes (44.4%) at the horizontal watershed zone. Superior or inferior deviation of the horizontal watershed was ascertained in 69 eyes (33.3%). The frequency of the anastomosis and deviation did not differ significantly between age groups (P = 0.56 and 0.96, respectively). Mean CCT of all eyes was 221 ± 80 μm. CCT was significantly greater in eyes with anastomosis than in those without (233 ± 73 μm vs 210 ± 83 μm, P < 0.05). However, CCT did not differ significantly between eyes with and without deviation of the horizontal watershed zone (223 ± 74 μm vs 219 ± 82 μm).ConclusionsVenous anastomosis at the horizontal watershed zone as well as superior or inferior deviation of the zone were frequently observed in normal eyes. CCT was greater in eyes with than in those without anastomosis, suggesting subclinical vortex vein congestion.
Prognostic indicators based on inflammatory and nutritional factors after pancreaticoduodenectomy for pancreatic cancer
PurposeWe evaluated prognostic indicators based on inflammatory and nutritional factors, namely, the modified Glasgow Prognostic Score (mGPS), the Prognostic Nutritional Index (PNI), the neutrophil/lymphocyte ratio (NLR), and the platelet/lymphocyte ratio (PLR), to determine their efficiency and significance after pancreaticoduodenectomy for pancreatic cancer.MethodsThe subjects of this study were 46 patients who underwent pancreaticoduodenectomy for pancreatic cancer between October 2007 and December 2014. Patients were divided into preoperative mGPS (0/1 and 2), PNI (<40 and ≥40), NLR (<2.5 and ≥2.5), and PLR (<200 and ≥200) groups, to evaluate various perioperative outcomes.ResultsHemoglobin concentrations were significantly lower (P = 0.019), whereas intra-abdominal bleeding was significantly higher (P = 0.040) in the PNI (<40) group than in the PNI (≥40) group. The incidence of postoperative pneumonia was significantly higher in the mGPS (2) group (P = 0.009), and surgical complications greater than grade 3 (Clavien–Dindo classification) were significantly increased in the NLR (≥2.5) group (P = 0.041). Overall survival rates in the PNI (<40) (P = 0.019), NLR (≥2.5) (P = 0.001), and PLR (≥200) (P < 0.001) groups were significantly lower than those in the other groups. The PLR was the only independent prognostic indicator (P = 0.002) according to multivariate analysis.ConclusionsThe mGPS, PNI, and NLR were effective predictive indicators of postoperative complications. The PLR was the most useful prognostic indicator for pancreatic cancer patients after pancreaticoduodenectomy.
The attenuation value of preoperative computed tomography as a novel predictor for pancreatic fistula after pancreaticoduodenectomy
PurposePancreatic fistula (PF) is the most serious complication following pancreaticoduodenectomy (PD). This study was performed to identify new clinical factors that may predict the development of PF after PD to improve perioperative management.MethodsSeventy-five consecutive patients who underwent PD from 2012 to 2015 were evaluated. The patients’ perioperative data including the computed tomography (CT) parameters were collected. The minimum, maximum, and mean CT attenuation values (HUmin, HUmax, and HUmean, respectively) were extracted from the pancreatic parenchyma (≥ 100 pixels), and the standard deviation of these values (HUSD) was determined from the slice in which the superior mesenteric and splenic veins were merged. PF was defined as grade B or C according to the International Study Group for Pancreatic Fistula criteria.ResultsThe PF occurrence rate (grade B or C) was 25.3% in 75 patients. A multivariate analysis identified a larger HUSD (odds ratio 3.092; 95% CI 1.018–9.394) and higher amylase concentration in drainage fluid on postoperative day 1 (odds ratio 1.0001; 95% CI 1.00001–1.00022) as significant risk factors for PF.ConclusionsThe HUSD of preoperative CT attenuation values in the pancreatic parenchyma was found to be an independent predictor for PF after PD and it might therefore positively contribute to the perioperative management of PD.
Topoisomerase I expression in tumors as a biological marker for CPT-11 chemosensitivity in patients with colorectal cancer
Irinotecan (CPT-11) is used as a first- and second-line chemotherapy for advanced or recurrent colorectal cancer (CRC). However, only 20%–30% of patients show an objective response to CPT-11 and the drug has severe toxicities, such as delayed-onset diarrhea, neutropenia, nausea, and vomiting. It is important to select patients who will demonstrate sensitivity to CPT-11 treatment to avoid unnecessary drug toxicities and to introduce anticancer treatment benefits to CRC patients. DNA topoisomerase I (Topo I) is essential for vital cellular processes such as DNA replication, transcription, translation, recombination, and repair. This article reviews the possibility of assessing Topo I protein expression in tumors as a biological marker for CPT-11 treatment in CRC.
A Newly Developed Method-Based Xanthine Oxidoreductase Activities in Various Human Liver Diseases
Studies evaluating xanthine oxidoreductase (XOR) activities in comprehensive liver diseases are scarce, and different etiologies have previously been combined in groups for comparison. To accurately evaluate XOR activities in liver diseases, the plasma XOR activities in etiology-based comprehensive liver diseases were measured using a novel, sensitive, and accurate assay that is a combination of liquid chromatography and triple quadrupole mass spectrometry to detect [13C2, 15N2]uric acid using [13C2, 15N2]xanthine as a substrate. We also mainly evaluated the association between the plasma XOR activities and parameters of liver tests, purine metabolism-associated markers, oxidative stress markers, and an inflammation marker. In total, 329 patients and 32 controls were enrolled in our study. Plasma XOR activities were generally increased in liver diseases, especially in the active phase, such as in patients with hepatitis C virus RNA positivity, those with abnormal alanine transaminase (ALT) levels in autoimmune liver diseases, and uncured hepatocellular carcinoma patients. Plasma XOR activities were numerically highest in patients with acute hepatitis B. Plasma XOR activities were closely correlated with parameters of liver tests, especially serum ALT levels, regardless of etiology and plasma xanthine levels. Our results indicated that plasma XOR activity might reflect the active phase in various liver diseases.
Successful resection of a slow-growing synchronous pulmonary metastasis from distal cholangiocarcinoma resected 3.5 years after initial surgery: a case report
Background A few reports have described the effectiveness of resection for recurrent cholangiocarcinoma. However, none have described resection of synchronous pulmonary metastasis from distal cholangiocarcinoma. We report the first case, to the best of our knowledge, of a slow-growing synchronous pulmonary metastasis from distal cholangiocarcinoma resected 3.5 years after the initial surgery. Case presentation A 67-year-old Japanese man with a diagnosis of distal cholangiocarcinoma was referred to our hospital. Thickening of the distal bile duct and an air-space pattern in the upper lobe of the left lung were detected by preoperative computed tomography. He underwent pancreaticoduodenectomy for the distal cholangiocarcinoma. Follow-up chest computed tomography demonstrated that the air-space pattern in the left lung had gradually enlarged. Thoracoscopic left S6 segmentectomy with lymph node dissection was performed 3.5 years after the initial surgery. Histopathology of the resected specimen revealed a solitary metastasis from distal cholangiocarcinoma with lepidic growth. We diagnosed the patient with a solitary synchronous pulmonary metastasis from distal cholangiocarcinoma. Conclusions Surgical resection might offer better long-term survival to patients with synchronous pulmonary metastasis from distant cholangiocarcinoma than nonsurgical treatments. Pulmonary metastasis from distal cholangiocarcinoma may exhibit a lepidic pattern. Therefore, because of the possibility of synchronous pulmonary metastasis, pulmonary resection should be considered for patients with lepidic lesions who have been diagnosed with distal cholangiocarcinoma.