20 results on '"Yasuhiko, Hayashi"'
Search Results
2. Thyrotropin-secreting pituitary adenomas induce left atrial enlargement with subclinical atrial fibrillation: an echocardiographic study
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Kenji Yoshiki, Masaya Shimojima, Mitsutoshi Nakada, Sho Takata, Yasuhiko Hayashi, Osamu Tachibana, Yumie Takeshita, Yasuo Sasagawa, and Toshinari Takamura
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Cardiac function curve ,medicine.medical_specialty ,Endocrinology, Diabetes and Metabolism ,Thyrotropin ,030209 endocrinology & metabolism ,Ventricular Function, Left ,03 medical and health sciences ,0302 clinical medicine ,Endocrinology ,Pituitary adenoma ,Diabetes mellitus ,Internal medicine ,Atrial Fibrillation ,Left atrial enlargement ,Humans ,Medicine ,Pituitary Neoplasms ,Subclinical infection ,Ejection fraction ,business.industry ,Thyroid ,Stroke Volume ,Atrial fibrillation ,medicine.disease ,medicine.anatomical_structure ,Echocardiography ,cardiovascular system ,Cardiology ,business ,030217 neurology & neurosurgery - Abstract
Thyrotropin-secreting pituitary adenoma (TSHoma) is rare but occasionally causes cardiovascular complications such as atrial fibrillation (AF) due to hyperthyroidism. Graves' disease (GD) is a common hyperthyroid condition often associated with subclinical AF. Some reports have shown echocardiographic changes in patients with GD. We aimed to evaluate the preoperative cardiac function in patients with TSHomas and compared the results among patients with TSHomas and GD and control subjects. Patients with TSHomas (n = 6) and GD (n = 20) were compared with control subjects with normal cardiac function (n = 20) based on echocardiographic findings. The average age, sex, and proportions of patients with a history of diabetes mellitus and hypertension were equal in each group, and the AF prevalence was matched in patients with TSHomas and GD. The values of left ventricular end-diastolic diameter (LVEDd), left ventricular end-systolic diameter (LVEDs), left ventricular ejection fraction (LVEF), and left atrial diameter (LAD) were used to assess cardiac function. In echocardiography, LAD showed a significant difference between patients with TSHomas and control subjects (p = 0.026). The mean LAD values were 36.9 ± 7.1, 38.2 ± 8.9, and 28.7 ± 3.9 mm for patients with TSHomas and GD and control subjects, respectively. There were no significant differences in other echocardiographic parameters among the groups. Before treatment, serum thyroid hormone levels (free triiodothyronine and thyroxin) were not significantly different among patients with TSHomas and GD. We found that patients with TSHomas or GD had enlarged LADs. This finding suggests that AF may be more hidden in patients with TSHomas than previously reported.
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- 2021
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3. Controlling Electronic States of Few-walled Carbon Nanotube Yarn via Joule-annealing and p-type Doping Towards Large Thermoelectric Power Factor
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Hirotaka Inoue, May Thu Zar Myint, Takeshi Nishikawa, Kazuki Omoto, Aung Ko Ko Kyaw, Yasuhiko Hayashi, and Yoshifumi Yamashita
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Materials science ,Annealing (metallurgy) ,lcsh:Medicine ,02 engineering and technology ,Carbon nanotube ,010402 general chemistry ,01 natural sciences ,Article ,law.invention ,Nanoscience and technology ,law ,Seebeck coefficient ,Thermoelectric effect ,lcsh:Science ,Multidisciplinary ,Dopant ,business.industry ,lcsh:R ,Doping ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Semiconductor ,Amorphous carbon ,Optoelectronics ,lcsh:Q ,0210 nano-technology ,business - Abstract
Flexible, light-weight and robust thermoelectric (TE) materials have attracted much attention to convert waste heat from low-grade heat sources, such as human body, to electricity. Carbon nanotube (CNT) yarn is one of the potential TE materials owing to its narrow band-gap energy, high charge carrier mobility, and excellent mechanical property, which is conducive for flexible and wearable devices. Herein, we propose a way to improve the power factor of CNT yarns fabricated from few-walled carbon nanotubes (FWCNTs) by two-step method; Joule-annealing in the vacuum followed by doping with p-type dopants, 2,3,5,6-tetrafluo-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Numerical calculations and experimental results explain that Joule-annealing and doping modulate the electronic states (Fermi energy level) of FWCNTs, resulting in extremely large thermoelectric power factor of 2250 µW m−1 K−2 at a measurement temperature of 423 K. Joule-annealing removes amorphous carbon on the surface of the CNT yarn, which facilitates doping in the subsequent step, and leads to higher Seebeck coefficient due to the transformation from (semi) metallic to semiconductor behavior. Doping also significantly increases the electrical conductivity due to the effective charge transfers between CNT yarn and F4TCNQ upon the removal of amorphous carbon after Joule-annealing.
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- 2020
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4. Mortality impact of post-discharge myocardial infarction size after percutaneous coronary intervention: a patient-level pooled analysis from the 4 large-scale Japanese studies
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Yoshito Yamamoto, Shuichiro Kaji, Takeshi Morimoto, Satoru Suwa, Masaharu Akao, Takao Kato, Koh Ono, Yoshihisa Nakagawa, Hideo Nishikawa, Tetsuya Ishikawa, Kyohei Yamaji, Yutaka Furukawa, Yoshiki Takatsu, Yasuhiko Hayashi, Naritatsu Saito, Kazushige Kadota, Kenji Ando, Yusuke Yoshikawa, Toshiya Muramatsu, Satoshi Shizuta, Shunichi Miyazaki, Hiroki Shiomi, Hirotoshi Watanabe, Takashi Tamura, Yoshikazu Hiasa, and Takeshi Kimura
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Male ,medicine.medical_specialty ,medicine.medical_treatment ,Myocardial Infarction ,030204 cardiovascular system & hematology ,Risk Assessment ,03 medical and health sciences ,Percutaneous Coronary Intervention ,0302 clinical medicine ,Japan ,Risk Factors ,Internal medicine ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Registries ,030212 general & internal medicine ,Myocardial infarction ,Creatine Kinase ,Aged ,biology ,Proportional hazards model ,business.industry ,Incidence ,Incidence (epidemiology) ,Percutaneous coronary intervention ,Stent ,Drug-Eluting Stents ,General Medicine ,Middle Aged ,medicine.disease ,Survival Analysis ,Patient Discharge ,Treatment Outcome ,Conventional PCI ,Cohort ,biology.protein ,Cardiology ,Female ,Creatine kinase ,Cardiology and Cardiovascular Medicine ,business - Abstract
It is unknown whether there is a threshold of creatine kinase (CK) or CK-MB affecting the subsequent mortality for post-discharge myocardial infarction (PDMI) after percutaneous coronary intervention. Current study sought to evaluate the impact of PDMI. The study population included 30,051 patients with successful coronary stenting and discharged alive in the pooled patient-level database of 4 Japanese studies (j-Cypher registry, CREDO-Kyoto PCI/CABG registry cohort-2, RESET, and NEXT). During 4.4 ± 1.4 year follow-up, 915 patients experienced PDMI (cumulative 5-year incidence of 3.6%). Among 466 patients with available peak CK ratio (peak CK/upper limit of normal), peak CK ratio (
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- 2018
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5. Radiation-induced gliomas: a report of four cases and analysis of molecular biomarkers
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Mitsutoshi Nakada, Yasuo Sasagawa, Masashi Kinoshita, Katsuyoshi Miyashita, Sumihito Nobusawa, Tsunehito Nakao, Hemragul Sabit, Hideaki Yokoo, Yasushi Takabatake, and Yasuhiko Hayashi
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Adult ,Male ,Proto-Oncogene Proteins B-raf ,X-linked Nuclear Protein ,Cancer Research ,Pathology ,medicine.medical_specialty ,IDH1 ,Biology ,Gene mutation ,IDH2 ,Histones ,03 medical and health sciences ,0302 clinical medicine ,Glioma ,Biomarkers, Tumor ,medicine ,Humans ,Telomerase reverse transcriptase ,Telomerase ,ATRX ,Neoplasm Staging ,Radiotherapy ,Brain Neoplasms ,Sequence Analysis, DNA ,General Medicine ,Middle Aged ,medicine.disease ,Immunohistochemistry ,Isocitrate Dehydrogenase ,Isocitrate dehydrogenase ,Oncology ,030220 oncology & carcinogenesis ,Mutation ,Cancer research ,Female ,Neurology (clinical) ,Tumor Suppressor Protein p53 ,030217 neurology & neurosurgery - Abstract
Radiation-induced glioma (RIG) is a rare secondary glioma. The tumors morphologically resemble their sporadically arising counterparts. Recently, the WHO classification of tumors of the central nervous system was revised to incorporate molecular biomarkers together with classic histological features. The status of molecular biomarkers in RIG, however, remains unclear. The objective of this study was to investigate if commonly accepted glioma-specific biomarkers are relevant in RIGs. Among 269 gliomas diagnosed as WHO grade 2, 3 and 4 in our institution, four were diagnosed as RIGs. Immunohistochemical (IHC) staining for isocitrate dehydrogenase 1 (IDH1), p53, alpha thalassemia/mental retardation syndrome X-linked (ATRX), and H3K27M, and direct DNA sequencing of IDH1/2, telomerase reverse transcriptase (TERT) promoter, Histone H3.3 (H3F3A) and B-Raf (BRAF) genes was performed. All tumor specimens were IDH1-, p53- and H3K27M-negative. The nuclei of tumor cells in all cases exhibited positive staining for ATRX. In direct DNA sequencing analysis, no IDH1, IDH2, TERT promoter, H3F3A or BRAF mutations were found in any of the cases. Our findings suggest that these characteristic glioma-associated molecular mutations may be rare events in RIGs. More RIGs need to be tested for analysis of molecular biomarkers to clarify the clinical and histopathological spectra of this tumor.
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- 2017
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6. Contribution of sellar dura integrity to symptom manifestation in pituitary adenomas with intratumoral hemorrhage
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Yasuo Sasagawa, Masahiro Oishi, Issei Fukui, Osamu Tachibana, Mitsutoshi Nakada, Fumiaki Ueda, Yasuhiko Hayashi, and Daisuke Kita
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Adenoma ,Male ,medicine.medical_specialty ,Endocrinology, Diabetes and Metabolism ,Dura mater ,medicine.medical_treatment ,Symptom ,Hemorrhage ,Asymptomatic ,03 medical and health sciences ,Magnetic resonance imaging ,0302 clinical medicine ,Endocrinology ,Hematoma ,Pituitary adenoma ,medicine ,Humans ,Pituitary Neoplasms ,Aged ,Retrospective Studies ,Diplopia ,Transsphenoidal surgery ,business.industry ,Middle Aged ,medicine.disease ,Surgery ,Treatment Outcome ,medicine.anatomical_structure ,Intratumoral hemorrhage ,030220 oncology & carcinogenesis ,Cavernous sinus ,Regression Analysis ,Female ,medicine.symptom ,business ,030217 neurology & neurosurgery - Abstract
Purpose: Although hemorrhage within pituitary adenomas frequently exacerbates the symptoms, there are many grades of severity. Moreover, the contributing factors for symptom severity are still controversial. Methods: This retrospective study included 82 patients who underwent transsphenoidal surgery for pituitary adenomas with intratumoral hemorrhage. The grades of preoperative symptoms were classified into group A, asymptomatic or minor symptoms; group B, moderate symptoms sufficient for complain; and group C, severe symptoms disturbing daily life. Results: The hemorrhage volume within an adenoma was significantly higher in group C (92.6%) than in groups A (48.6%) and B (58.7%). Both headache and diplopia were dominant in group C, occurring in 72.2% and 27.8% of the patients, respectively. In group C, there was no significant difference in frequency between adenoma extensions into the sphenoid sinus (0%) and involvement of the cavernous sinus of Knosp grade 4 (0%), and extensions into the suprasellar region were not common (38.9%). The most distinctive feature was that “no extrasellar extension” was found only in group C (41.2%), and “multidirectional extension” was not detected in this group (0%). Multiple regression analysis revealed that the most powerful determining factors were the high frequencies of intratumoral hemorrhage and lack of extrasellar and multidirectional extensions. Conclusion: Rapid volume expansion of a hematoma and lack of extension or unidirectional extension might lead to significant compression of the sellar and surrounding structures. Of note, the integrity of the sellar dura might contribute to the acute onset of symptom manifestations caused by hemorrhage in pituitary adenomas. © 2017 Springer Science+Business Media, LLC, Embargo Period 12 months
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- 2017
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7. Clinical characteristics of acromegalic patients with empty sella and their outcomes following transsphenoidal surgery
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Issei Fukui, Mitsutoshi Nakada, Hideaki Iizuka, Yasuo Sasagawa, Osamu Tachibana, Masahiro Oishi, and Yasuhiko Hayashi
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Male ,medicine.medical_specialty ,Sphenoid Sinus ,Adenoma ,Empty sella turcica ,Endocrinology, Diabetes and Metabolism ,medicine.medical_treatment ,Neurosurgical Procedures ,03 medical and health sciences ,0302 clinical medicine ,Endocrinology ,Cerebrospinal fluid ,Acromegaly ,medicine ,Humans ,Growth hormone ,Aged ,Retrospective Studies ,Transsphenoidal surgery ,medicine.diagnostic_test ,business.industry ,Empty Sella Syndrome ,Magnetic resonance imaging ,Middle Aged ,medicine.disease ,Magnetic Resonance Imaging ,Occult ,Surgery ,Sella turcica ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,Female ,Subarachnoid space ,business ,030217 neurology & neurosurgery - Abstract
Purpose: To analyze the clinical characteristics of acromegalic patients with empty sella (ES, herniation of the subarachnoid space within the sella turcica) and the impact of ES on transsphenoidal surgery in such patients. Methods: Seventy-eight patients, newly diagnosed with acromegaly who underwent transsphenoidal surgery were included. ES was defined as the pituitary gland and adenoma occupying less than 50% of the sella turcica on midsagittal magnetic resonance (MR) imaging. Results: Twelve patients (15.4%), predominantly female (10 women, p = .047), had ES in preoperative MR imaging. ES patients had smaller mean tumor diameter (6.3 mm) than non-ES patients (11.2 mm, p = .001). In preoperative MR imaging, occult adenoma was found in three (25%) ES and three (4.5%) non-ES patients (p = .044). Intraoperative cerebrospinal fluid (CSF) leakage was more frequent in the ES patients than in the non-ES patients (58.3 vs. 25.8%, p = .024). This led to an increased rate of sellar floor reconstruction using abdominal fat and/or postoperative lumber drainage in the ES patients (ES: 41.7 vs. non-ES: 16.7%, p = .063). Endocrinological remission after surgery was more frequent in the non-ES patients (72.7%) than in the ES patients (58.3%) (p = .248). Conclusions: Co-existence of acromegaly with ES is not rare, and is associated with occult adenoma, intra/postoperative CSF leakage, and a worse endocrinological outcome after transsphenoidal surgery; although, the underlying mechanism remains unclear. © 2017 Springer Science+Business Media New York, Embargo Period 12 months
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- 2017
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8. Ultrasonic-assisted synthesis of ZnO nano particles decked with few layered graphene nanocomposite as photoanode in dye-sensitized solar cell
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Karthik Paneer Selvam, Yasuhiko Hayashi, Satish Bykkam, Bikshalu Kalagadda, and Venkateshwara Rao Kalagadda
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Nanocomposite ,Materials science ,Graphene ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Tin oxide ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,law.invention ,Dye-sensitized solar cell ,Chemical engineering ,law ,Solar cell ,Electrical and Electronic Engineering ,Thin film ,Fourier transform infrared spectroscopy ,0210 nano-technology - Abstract
ZnO decked few layered graphene (FLG; 1.0, 2.0 and 3.0 wt%) nanocomposites were synthesized by simple and cost effective way using ultrasonic-assisted synthesis method. The morphological, optical and structural properties of as-synthesized nanocomposites were analyzed by field emission scanning electron microscopy and high-resolution transmission electron microscopy, UV–Visible spectroscopy with diffuse reflectance, fourier transform infrared spectroscopy, X-ray diffractometry and ramam spectroscopy. The synthesized FLG (1.0, 2.0 and 3.0 wt%)/ZnO nanocomposite were used as photoanode materials and deposited as thin films on fluorine-doped tin oxide substrate by doctor blade method for dye-sensitized solar cell (DSSC) fabrication. By varying the FLG weight percentage (1.0, 2.0 and 3.0 wt%) in ZnO nanocomposites the power conversion efficiency (PCE) in DSSC was optimized. Using N719 dye the current density–voltage (J–V) was measured under AM 1.5G, 100 m W/m2 of the solar simulator. Results obtained after optimization showed PCE of 4.61% at the suitable FLG (1.0 wt%)/ZnO, compared to ZnO and other photoanodes.
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- 2017
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9. Carotid artery protrusion and dehiscence in patients with acromegaly
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Mariko Doai, Yasuo Sasagawa, Mitsutoshi Nakada, Hisao Tonami, Hideaki Iizuka, Osamu Tachibana, and Yasuhiko Hayashi
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Adult ,Male ,medicine.medical_specialty ,Systemic disease ,Sphenoid Sinus ,Endocrinology, Diabetes and Metabolism ,Carotid arteries ,030209 endocrinology & metabolism ,Dehiscence ,03 medical and health sciences ,0302 clinical medicine ,Endocrinology ,Acromegaly ,medicine ,Humans ,In patient ,Sinus (anatomy) ,Aged ,Retrospective Studies ,Tumor size ,business.industry ,Middle Aged ,medicine.disease ,Carotid Arteries ,medicine.anatomical_structure ,Cavernous sinus ,Female ,Radiology ,Tomography, X-Ray Computed ,business ,030217 neurology & neurosurgery - Abstract
Purpose Acromegaly is a systemic disease which causes multiple bony alterations. Some authors reported that acromegalic patients have risk factors for an intraoperative vascular injury due to the specific anatomical features of their sphenoid sinus. The objective of our study was to analyze the anatomic characteristics of sphenoid sinus in acromegalic patients compared with controls, by evaluation of computed tomography (CT) findings. Methods We examined 45 acromegalic (acromegaly group) and 45 non-acromegalic patients (control group) with pituitary adenomas who were matched for sex, age, height, tumor size, and cavernous sinus invasion (Knosp grade). Preoperative CT of the pituitary region including the sphenoid sinus was used to evaluate the following anatomic characteristics: type of sphenoid sinus (sellar or pre-sellar/conchal); intrasphenoid septa (non/single or multiple); carotid artery protrusion; carotid artery dehiscence; intercarotid distance. Results Sixteen acromegalic patients (35.5 %) and 6 controls (13.3 %) had carotid artery protrusion. Additionally, 10 acromegalic patients (22.2 %) and 3 controls (6.6 %) had carotid artery dehiscence. Carotid artery protrusion and dehiscence were more frequent in the acromegaly group than in control group (p = 0.013 and 0.035, respectively). Other anatomic characteristics (type of sphenoid sinus, intrasphenoid septa, and intracarotid distance) showed no significant differences between acromegaly and control groups. Conclusions Our study suggests that carotid artery protrusion and dehiscence occur more frequently among acromegalic patients, compared with non-acromegalic patients. It is important for surgeons to be aware of these anatomic variations to avoid vital complications, such as carotid injuries, during surgery.
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- 2016
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10. Simultaneous ventriculoperitoneal shunt removal and endoscopic third ventriculostomy for three patients previously treated for intracranial germ cell tumors more than 20 years ago
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Yasuhiko Hayashi, Masahiro Oishi, Daisuke Kita, Mitsutoshi Nakada, and Issei Fukui
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Adult ,Male ,medicine.medical_specialty ,Ventricular system ,Ventriculoperitoneal Shunt ,03 medical and health sciences ,Postoperative Complications ,0302 clinical medicine ,Cerebrospinal fluid ,medicine ,Humans ,Longitudinal Studies ,Third Ventricle ,Endoscopes ,Third ventricle ,business.industry ,Endoscopic third ventriculostomy ,General Medicine ,Middle Aged ,Neoplasms, Germ Cell and Embryonal ,medicine.disease ,Magnetic Resonance Imaging ,Shunt (medical) ,Hydrocephalus ,Surgery ,Treatment Outcome ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,Pediatrics, Perinatology and Child Health ,Neurology (clinical) ,Germ cell tumors ,Neurosurgery ,business ,030217 neurology & neurosurgery - Abstract
Obstructive hydrocephalus is the most common complication of intracranial germ cell tumors (IGCTs). Although ventriculoperitoneal shunts (VPSs) were previously used for treating this condition, they have recently been replaced by endoscopic third ventriculostomy (ETV), as the latter can avoid various complications caused by a VPS and can preserve physiological cerebrospinal fluid (CSF) dynamics. Therefore, if a VPS malfunctioned in patients who had previously been treated for IGCTs, it seems reasonable to consider removing the problematic VPS, followed by ETV, as long as magnetic resonance imaging reveals third ventricle floor ballooning and the cause of obstruction in the ventricular system, which are indicators for ETV. Here, we present the cases of three patients who underwent simultaneous removal of malfunctioning VPSs and ETV, more than 20 years (range 20–27 years) after initial treatment for IGCT and relevant obstructive hydrocephalus. Despite a relatively long shunt dependency, their obstructive hydrocephalus was well-managed by ETV, probably because CSF absorptive capacity remained intact after IGCT ablation by radio-chemotherapy. Patients with previously treated IGCTs can thus be released from the need for a VPS, regardless of long-term shunt dependency.
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- 2016
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11. Hydrothermal approached 1-D molybdenum oxide nanostructures for high-performance supercapacitor application
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Reddy, R. Kiran Kumar, primary, Kailasa, Saraswathi, additional, Rani, B. Geetha, additional, Jayarambabu, N., additional, Yasuhiko, Hayashi, additional, Ramana, G. Venkata, additional, and Rao, K. Venkateswara, additional
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- 2019
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12. Cross-Polarized Surface-Enhanced Infrared Spectroscopy by Fano-Resonant Asymmetric Metamaterials
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Shuhei Hara, Kenji Tsuruta, Takuo Tanaka, Atsushi Ishikawa, and Yasuhiko Hayashi
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Multidisciplinary ,Materials science ,Field (physics) ,business.industry ,Science ,Physics::Optics ,Metamaterial ,Fano resonance ,Infrared spectroscopy ,02 engineering and technology ,Fano plane ,021001 nanoscience & nanotechnology ,01 natural sciences ,Signal ,Article ,Transmission (telecommunications) ,0103 physical sciences ,Metamaterial absorber ,Medicine ,Optoelectronics ,010306 general physics ,0210 nano-technology ,business - Abstract
Plasmonic metamaterials have overcome fundamental limitations in conventional optics by their capability to engineer material resonances and dispersions at will, holding great promise for sensing applications. Recent demonstrations of metamaterial sensors, however, have mainly relied on their resonant nature for strong optical interactions with molecules, but few examples fully exploit their functionality to manipulate the polarization of light. Here, we present cross-polarized surface-enhanced infrared absorption (SEIRA) by the Fano-resonant asymmetric metamaterial allowing for strong background suppression as well as significant field enhancement. The metamaterial is designed to exhibit the controlled Fano resonance with the cross-polarization conversion property at 1730 cm−1, which spectrally overlaps with the C=O vibrational mode. In the cross-polarized SEIRA measurement, the C=O mode of poly(methyl methacrylate) molecules is clearly observed as a distinct dip within a Fano-resonant transmission peak of the metamaterial. The vibrational signal contrast is then improved based on the cross-polarized detection scheme where only the light interacting with the metamaterial-molecular coupled system is detected by totally eliminating the unwanted background light. Our metamaterial approach achieves the zeptomole sensitivity with a large signal-to-noise ratio in the far-field measurement, paving the way toward the realization of ultrasensitive IR inspection technologies.
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- 2017
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13. Azidation of polyesters having pendent functionalities by using NaN3 or DPPA–DBU and photo-crosslinking of the azidopolyesters
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Hiroki Tanaka, Yasuhiko Hayashi, Yosuke Shibata, and Akinori Takasu
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Polyester ,Reaction mechanism ,Condensation polymer ,Polymers and Plastics ,Chemistry ,Polymer chemistry ,Materials Chemistry ,Side reaction ,Nucleophilic substitution ,Chemical modification ,Organic chemistry ,Trifluoromethanesulfonate ,Catalysis - Abstract
Dehydration polycondensation of bromoadipic acid and methylsuccinic acid with 1,4-butanediol was performed at 80 °C to synthesize aliphatic polyesters containing pendent bromo groups without dehydrobromination using scandium trifluoromethanesulfonate as the catalyst. Azidation of poly(butylene bromoadipate-co-butylene methylsuccinate) also proceeded to generate poly(butylene azidoadipate-co-butylene methylsuccinate) (Mn=10.4 × 103). We successively photo-crosslinked the resultant azidopolyesters by UV irradiation. We also described azidation of polyesters having pendent hydroxyl groups by using the ‘diphenylphosphoryl azide-1,8-diazabicyclo[5.4.0]undec-7-ene substitution strategy’ to produce water-soluble polyesters containing pendent azido groups (Mn=7.5 × 103).
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- 2011
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14. Detection of the development of late-onset idiopathic aqueductal stenosis (LIAS) by chronological magnetic resonance imaging: a case report
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Masashi Kinoshita, Jun-ichiro Hamada, Takumi Taniguchi, Tomohiro Kitabayashi, Michiko Okajima, Yasuhiko Hayashi, and Daisuke Kita
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Male ,Ventriculostomy ,medicine.medical_specialty ,Adolescent ,medicine.medical_treatment ,Late onset ,Ventricular system ,medicine ,Humans ,Third Ventricle ,medicine.diagnostic_test ,business.industry ,Endoscopic third ventriculostomy ,Magnetic resonance imaging ,General Medicine ,medicine.disease ,Magnetic Resonance Imaging ,Hydrocephalus ,Surgery ,Aqueductal stenosis ,Pituitary Gland ,Pediatrics, Perinatology and Child Health ,Neurology (clinical) ,Neurosurgery ,Radiology ,business ,Diabetes Insipidus - Abstract
Late-onset idiopathic aqueductal stenosis (LIAS) has been recognized as one of the clinical entities of adulthood hydrocephalus for decades, although there have been no radiological reports that show normal ventricular systems before the development of LIAS. We present here an adolescent case of LIAS with a previously normal ventricular system on magnetic resonance imaging (MRI). A 17-year-old boy had been suffering from chronic headaches and mild intellectual disability (MID) since he became a teenager, and this had prevented him from leading an ordinary school life. MRIs on admission showed triventriculomegaly from the aqueductal stenosis that had not been detected on previous MRIs, at least until the age of 6. An endoscopic third ventriculostomy was successfully performed, which improved both the headache and the MID. The developmental mechanism of LIAS remains unclear, although the membranous ependymal-like tissue observed in the aqueduct suggested the preceding existence of an inflammatory process around this region. To the best of our knowledge, this case was noteworthy because the development of LIAS was clearly demonstrated on MRI for the first time.
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- 2014
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15. Primary cardiac lymphoma diagnosed by endomyocardial biopsy using transthoracic echocardiography in the substernal window
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Yasuhiko Hayashi, Yoshiko Masaoka, Nobuo Shiode, Toshiharu Oka, Yasuki Kihara, and Hironori Ueda
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medicine.medical_specialty ,Chemotherapy ,medicine.diagnostic_test ,business.industry ,medicine.medical_treatment ,Ultrasound ,Primary Cardiac Lymphoma ,General Medicine ,medicine.disease ,Endomyocardial biopsy ,Biopsy ,Medicine ,Tissue diagnosis ,Radiology, Nuclear Medicine and imaging ,Radiology ,business ,Diffuse large B-cell lymphoma ,Cardiac Tumors - Abstract
We report a case of a 56-year-old man with a cardiac tumor, which grew and spread rapidly in the right heart. Using transthoracic echocardiography (TTE) in the substernal window, a transvenous biopsy of the tumor was performed safely. The tissue diagnosis revealed a diffuse large B cell lymphoma. After undergoing chemotherapy, the tumor was completely cured and the patient continues to be in good health. A biopsy using TTE in the substernal window may be a useful method to diagnose right-sided extensive tumors.
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- 2013
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16. [Untitled]
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Yukihiko Gomyo, Yasuhiko Hayashi, Yasuaki Shimohara, Tomokazu Okimoto, Kaoru Yanagihara, Futoshi Tadehara, Hideya Yamamoto, Mamoru Toyofuku, Kotaro Sumii, Michinori Imazu, Nobuoki Kohno, and Yoshitaka Sekiguchi
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Pharmacology ,medicine.medical_specialty ,Percutaneous ,biology ,business.industry ,Vascular disease ,medicine.medical_treatment ,Angiotensin-converting enzyme ,General Medicine ,medicine.disease ,law.invention ,Restenosis ,Randomized controlled trial ,Quinapril ,law ,Angioplasty ,Internal medicine ,ACE inhibitor ,Cardiology ,biology.protein ,Medicine ,Pharmacology (medical) ,Cardiology and Cardiovascular Medicine ,business ,medicine.drug - Abstract
Experimental studies have demonstrated that vascular injury resulted in an induction of vascular angiotensin-converting enzyme (ACE), and have suggested that inhibition of vascular ACE might be important in the prevention of restenosis. The present study aimed to determine the effect of quinapril, an ACE inhibitor with high affinity to tissue ACE, on restenosis following coronary intervention. The design of this study was a prospective, randomized, open, and non-placebo controlled trial. Patients with ischemic heart disease were enrolled after successful percutaneous transluminal coronary angioplasty or stent implantation at 7 participating institutions. Two hundred and fifty-three patients with 294 lesions were randomly assigned to the quinapril (10-20 mg per day) group or control group. Administration of quinapril was continued for 3-6 months of the follow-up. Quantitative coronary angiography was performed before and after angioplasty and at follow-up. Core laboratory measurements were performed independently and blinded. Follow-up angiography was performed in 108 patients with 124 lesions in the quinapril group and in 107 patients with 130 lesions in the control group. The baseline characteristics and findings of angioplasty showed no significant differences between the two groups. However, in the quinapril group, restenosis per patient and per lesion was significantly lower (34.3% vs. 47.7%, p < 0.05 and 30.6% vs. 43.8%, p < 0.05). Multivariable analysis revealed that administration of quinapril independently contributed to reducing the restenosis per patient and per lesion (odds ratio, 0.73; 95% confidence interval, 0.54-0.99 and odds ratio, 0.75; 95% confidence interval, 0.57-0.99). In conclusion, quinapril significantly reduces restenosis following coronary intervention.
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- 2001
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17. Fabrication of tin-filled carbon nanofibres by microwave plasma vapour deposition and their in situ heating observation by environmental transmission electron microscopy
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Takumi Kanematsu, Takahisa Ota, Takahisa Yamamoto, Takahumi Ito, Yasuhiko Hayashi, Tomoharu Tokunaga, and Katsuhiro Sasaki
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Fabrication ,Materials science ,Nano Express ,Metal-filled CNF ,Scanning electron microscope ,Nanochemistry ,chemistry.chemical_element ,Nanotechnology ,In situ ETEM ,Condensed Matter Physics ,Nanofibre ,Heating ,Materials Science(all) ,chemistry ,Chemical engineering ,Transmission electron microscopy ,General Materials Science ,Graphite ,Tin ,Carbon ,Layer (electronics) - Abstract
Sn-filled carbon nanofibres (CNFs) are fabricated by microwave plasma chemical deposition. Scanning electron microscopy observations revealed the existence of a Sn island under the CNFs. The structure of the CNFs is investigated, and the behaviour of Sn in the internal space of CNFs is revealed by performing in situ heating observations by environmental transmission electron microscopy (ETEM). ETEM observations reveal that they have low-crystallized carbon wall and Sn occupies not only the CNF's internal space but also its carbon wall. The Sn inside the CNF is completely covered by the carbon wall. Further, the in situ heating observations reveal that Sn within the internal space and the carbon wall of the CNFs diffused to the outside during heating. Moreover, it is found that higher membered carbon rings and defects in the graphite layer act as diffusion routes between disordered carbon layers.
- Published
- 2013
- Full Text
- View/download PDF
18. High temperature in-situ observations of multi-segmented metal nanowires encapsulated within carbon nanotubes by in-situ filling technique
- Author
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Golap Kalita, T. Iijima, Masaki Tanemura, Tomoharu Tokunaga, Katsuhiro Sasaki, Yasuhiko Hayashi, Kotaro Kuroda, and Takuya Iwata
- Subjects
Materials science ,Chemical substance ,Nano Express ,Carbon nanotubes ,Nanowire ,Internal pressure ,Nanochemistry ,Nanotechnology ,Carbon nanotube ,Chemical vapor deposition ,Condensed Matter Physics ,in-situ filling method ,Metal nanowires ,law.invention ,Materials Science(all) ,Environmental TEM ,Transmission electron microscopy ,law ,Encapsulation ,General Materials Science ,Graphite ,Transmission electron microscopy (TEM) ,Composite material ,Melting temperature - Abstract
Multi-segmented one-dimensional metal nanowires were encapsulated within carbon nanotubes (CNTs) through in-situ filling technique during plasma-enhanced chemical vapor deposition process. Transmission electron microscopy (TEM) and environmental TEM were employed to characterize the as-prepared sample at room temperature and high temperature. The selected area electron diffractions revealed that the Pd4Si nanowire and face-centered-cubic Co nanowire on top of the Pd nanowire were encapsulated within the bottom and tip parts of the multiwall CNT, respectively. Although the strain-induced deformation of graphite walls was observed, the solid-state phases of Pd4Si and Co-Pd remain even at above their expected melting temperatures and up to 1,550 ± 50°C. Finally, the encapsulated metals were melted and flowed out from the tip of the CNT after 2 h at the same temperature due to the increase of internal pressure of the CNT.
- Published
- 2012
- Full Text
- View/download PDF
19. Growth and structure analysis of tungsten oxide nanorods using environmental TEM
- Author
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Naohiro Nakamura, Tomoharu Tokunaga, Takahisa Yamamoto, Kenta Tanaka, Yasuhiko Hayashi, Katsuhiro Sasaki, Tadashi Kawamoto, and Kotaro Kuroda
- Subjects
Materials science ,Nano Express ,tungsten ,Oxide ,Tungsten oxide ,chemistry.chemical_element ,Nanochemistry ,Nanotechnology ,Tungsten ,Condensed Matter Physics ,nanorod ,environmental TEM ,Crystal ,chemistry.chemical_compound ,Materials Science(all) ,chemistry ,Chemical engineering ,Environmental Transmission Electron Microscope ,General Materials Science ,Nanorod ,oxide ,Layer (electronics) - Abstract
WO3 nanorods targeted for applications in electric devices were grown from a tungsten wire heated in an oxygen atmosphere inside an environmental transmission electron microscope, which allowed the growth process to be observed to reveal the growth mechanism of the WO3 nanorods. The initial growth of the nanorods did not consist of tungsten oxide but rather crystal tungsten. The formed crystal tungsten nanorods were then oxidized, resulting in the formation of the tungsten oxide nanorods. Furthermore, it is expected that the nanorods grew through cracks in the natural surface oxide layer on the tungsten wire.
- Published
- 2012
- Full Text
- View/download PDF
20. Room-Temperature CW Operation of SQW Lasers on Si Grown with AiGaAs/AlGaP Intermediate Layers by MoCVD
- Author
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M. Umeno, Tetsuo Soga, Takashi Jimbo, T. Egawa, T. George, and Yasuhiko Hayashi
- Subjects
Threshold current ,Materials science ,Si substrate ,business.industry ,law ,Optoelectronics ,Metalorganic vapour phase epitaxy ,business ,Laser ,Differential quantum efficiency ,Lasing threshold ,Quantum well ,law.invention - Abstract
The heterointerfaces of single quantum wells (SQWs) and the characteristics of SQW lasers on Si substrates grown with Al0.5 Ga0 5As/Al0.55Ga0.45P intermediate layers (AlGaAs/AlGaP ILs) entirely by MOCVD are reported. The surface morphology and the heterointerfaces of SQWs grown on Si substrates with the AlGaAs/AlGaP ILs are smoother than those of the two-step-grown sample. The two-dimensional growth of the AlGaAs/AlGaP ILs on a Si substrate contributes to obtain the smooth heterointerface. The excellent lasing characteristics are obtained by the AlGaAs/AlGaP ILs, which are caused by the smooth heterointerfaces. The lasers grown with the AlGaAs/AlGaP ILs show the averaged threshold current density of 1.83 kA/cm2 and the averaged differential quantum efficiency of 51.9 % under cw condition at room temperature.
- Published
- 1991
- Full Text
- View/download PDF
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