40 results on '"Shuichi Okubo"'
Search Results
2. A Case of Dural Arteriovenous Fistula Involving the Inferior Petroclival Vein
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Kunihiko Osaka, Naohiro Osaka, Masahiko Kawanishi, Naoki Hayashi, Takashi Tamiya, and Shuichi Okubo
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medicine.medical_specialty ,medicine.anatomical_structure ,business.industry ,Medicine ,Arteriovenous fistula ,Inferior petrosal sinus ,Neurology (clinical) ,Cardiology and Cardiovascular Medicine ,business ,Vein ,medicine.disease ,Surgery - Published
- 2019
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3. A Ruptured Internal Carotid-Posterior Communicating Artery Aneurysm with Pure Acute Subdural Hematoma and Oculomotor Palsy without Subarachnoid Hemorrhage: A Literature Review
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Kunihiko Osaka, Atsushi Shindo, Masahiko Kawanishi, Takashi Tamiya, Shuichi Okubo, Naohiro Osaka, and Naoki Hayashi
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medicine.medical_specialty ,business.industry ,Medicine ,Radiology ,business ,Coil embolization - Published
- 2019
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4. Radiation Response of Negative Gate Biased SiC MOSFETs
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Takeshi Ohshima, Takahiro Makino, Yuki Tanaka, Toru Yoshie, Yasuto Hijikata, Shuichi Okubo, and Akinori Takeyama
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SiC ,Materials science ,radiation response ,01 natural sciences ,lcsh:Technology ,Article ,chemistry.chemical_compound ,MOSFET ,Gate oxide ,0103 physical sciences ,Silicon carbide ,General Materials Science ,Irradiation ,lcsh:Microscopy ,lcsh:QC120-168.85 ,010302 applied physics ,lcsh:QH201-278.5 ,010308 nuclear & particles physics ,business.industry ,lcsh:T ,Gamma ray ,gamma-rays ,gate bias ,chemistry ,lcsh:TA1-2040 ,Optoelectronics ,Field-effect transistor ,lcsh:Descriptive and experimental mechanics ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,business ,lcsh:Engineering (General). Civil engineering (General) ,Current density ,lcsh:TK1-9971 ,Voltage - Abstract
Silicon carbide (SiC) metal-oxide-semiconductor field effect transistors (MOSFETs) are expected as power electronic devices for high radiative conditions, including nuclear plants and space. Radiation response of commercial-grade prototype SiC MOSFETs with applying the gate bias is of interest, in terms of installation of the device in robots or sensors working under such radioactive circumstances. Due to gamma-rays irradiation, the threshold voltages (Vth) of samples with un- and negative-biased up to &minus, 4.5 V slightly shift toward the negative voltage side. In contrast, the positive bias of 2.25 V shifts Vth more negatively. Positive charge densities trapped in the gate oxide of un- and positive-biased samples increased with increasing dose. However, no significant increase was observed for negative-biased samples of &minus, 2.25 and &minus, 4.5 V. We calculated characteristic parameters for the accumulation of holes in the gate oxide, &sigma, pJp which is defined as the product of current density due to holes generated by irradiation and capture cross section for a hole in a trap, and it is lower for these negative biased samples compared with the unbiased case. Application of appropriate negative gate biases to SiC MOSFETs during irradiation suppresses accumulation of positive charges in the gate oxide and negative shift of Vth, due to irradiation.
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- 2019
5. The Importance of Recognizing Diffuse Idiopathic Skeletal Hyperostosis for Neurosurgeons: A Review
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Kenta Suzuki, Kimihiro Yoshino, Masatoshi Yunoki, Atsuhito Uneda, Shuichi Okubo, and Koji Hirashita
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medicine.medical_specialty ,Percutaneous ,Disease ,Review Article ,surgery ,03 medical and health sciences ,0302 clinical medicine ,Spinal fracture ,medicine ,Teriparatide ,Humans ,Diffuse Idiopathic Skeletal Hyperostosis ,030203 arthritis & rheumatology ,Hyperostosis, Diffuse Idiopathic Skeletal ,business.industry ,Ossification ,Soft tissue ,medicine.disease ,Surgery ,trauma ,spinal fracture ,Neurology (clinical) ,medicine.symptom ,business ,diffuse idiopathic skeletal hyperostosis ,030217 neurology & neurosurgery ,Calcification ,medicine.drug - Abstract
Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by calcification and ossification of the soft tissues, mainly ligaments and entheses. The spines of patients with DISH generally become increasingly rigid and osteoporotic, and fractures may occur after even a relatively minor traumatic event such as a ground-level fall. Moreover, the prevalence of DISH may be rapidly increasing in affluent societies. Thus, awareness of this condition is becoming more important for neurosurgeons when assessing trauma patients. For the present article, a literature review was conducted to summarize the current clinical, pathogenetic, and therapeutic knowledge of this disease. Furthermore, current treatment strategies for DISH-related spine injuries are also reviewed. Although the recommended treatment for spinal injuries in DISH patients is surgical, mainly through long-segment posterior fusion, rather than conservative options, stable fractures without any associated neurologic deficits have often been successfully managed with immobilization alone. Percutaneous instrumentation and the use of teriparatide may be useful depending on the surgical risks and patient neurological status.
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- 2016
6. A magnetic resonance imaging grading system for subarachnoid hemorrhage severity in a rat model
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Haining Zhang, Guohua Xi, Richard F. Keep, Shuichi Okubo, Hajime Shishido, Ya Hua, and Yusuke Egashira
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Neurologic Examination ,medicine.medical_specialty ,Subarachnoid hemorrhage ,medicine.diagnostic_test ,business.industry ,General Neuroscience ,Rat model ,Perforation (oil well) ,Magnetic resonance imaging ,Subarachnoid Hemorrhage ,medicine.disease ,Magnetic Resonance Imaging ,Severity of Illness Index ,Article ,Rats sprague dawley ,Rats ,nervous system diseases ,Rats, Sprague-Dawley ,Disease Models, Animal ,Severity of illness ,medicine ,Animals ,cardiovascular diseases ,Radiology ,business - Abstract
The endovascular perforation model of subarachnoid hemorrhage (SAH) has a large variation in outcomes. This may reflect differences in the SAH size.Magnetic resonance imaging (MRI) was performed 24h after endovascular perforation in adult male (n=58) and female (n=58) rats. Rats were divided into five grades according to MRI characteristics: grade 0: no SAH or intraventricular hemorrhage (IVH); grade 1: minimal or thin SAH without IVH; grade 2: minimal or thin SAH with IVH; grade 3: thick SAH without IVH; grade 4: thick SAH with IVH. We investigated whether MRI grading scale reflected severity of SAH (determined post mortem) and neurological score.There was a strong correlation between MRI grading scale and current SAH grading scale (P0.01) and neurological score (P0.01) in male rats. In female rats, there was also a strong correlation between MRI grading scale and SAH grading scale (P0.01) but not with neurological score (P=0.24).The current grading system is based on the amount of SAH and needs animal euthanasia to evaluate SAH severity. There is no useful grading system to classify severity of SAH without decapitating animals.We demonstrated a correlation between the MRI grading scale and the current SAH grading scale in an endovascular perforation rat model. The MRI grading scale allows evaluation of SAH severity without euthanizing animals.
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- 2015
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7. Multi-level isolated spinous process fractures with delayed deterioration observed radiographically: A case report
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Atsuhito Uneda, Shuichi Okubo, Masatoshi Yunoki, Kimihiro Yoshino, Kenta Suzuki, and Koji Hirashita
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medicine.medical_specialty ,Radiography ,Spinous process ,lcsh:Surgery ,Delayed deterioration ,lcsh:RC346-429 ,03 medical and health sciences ,0302 clinical medicine ,Rare case ,medicine ,Back pain ,Rest (music) ,lcsh:Neurology. Diseases of the nervous system ,030222 orthopedics ,integumentary system ,business.industry ,lcsh:RD1-811 ,musculoskeletal system ,Surgery ,medicine.anatomical_structure ,Traumatic injury ,Clay-shoveler's fracture ,Neurology (clinical) ,medicine.symptom ,business ,030217 neurology & neurosurgery - Abstract
We describe a rare case of multi-level isolated spinous process fractures not clearly detected on admission and subsequently diagnosed on radiography 2 months after traumatic injury. Early recognition of a small crack in the spinous process and treatment with rest and immobilization is crucial to prevent chronic back pain or stiffness.
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- 2016
8. A plastic-based bolometer array sensor using carbon nanotubes for low-cost infrared imaging devices
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Kenichiro Tsuda, Keishi Ohashi, Masaharu Imazato, Ersin Altintas, Toru Tabuchi, Shigeyuki Komatsubara, Ryosuke Kuribayashi, Hiroko Someya, Shuichi Okubo, and Kaoru Narita
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Conductive polymer ,Materials science ,business.industry ,Infrared ,Bolometer ,Isolator ,Metals and Alloys ,Substrate (electronics) ,Carbon nanotube ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,chemistry.chemical_compound ,Parylene ,chemistry ,law ,Thermal ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Instrumentation - Abstract
We have developed an infrared image sensor based on bolometers on a plastic substrate that is potentially ultra low-cost due to its simple structure consisting of mainly organic materials. The bolometer includes a thermal isolator made of a very low thermal conductive polymer (parylene) and a newly developed, highly sensitive (TCR
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- 2013
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9. Brain abscess caused by Nocardia asiatica
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Atsuhito Uneda, Shuichi Okubo, Koji Hirashita, Kimihiro Yoshino, Kenta Suzuki, and Masatoshi Yunoki
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Pathology ,medicine.medical_specialty ,Case Report ,Microbiology ,03 medical and health sciences ,0302 clinical medicine ,Nocardia asiatica ,medicine ,030212 general & internal medicine ,16S rRNA ,Brain abscess ,integumentary system ,biology ,business.industry ,Mortality rate ,Nocardia ,bacterial infections and mycoses ,medicine.disease ,biology.organism_classification ,bacteria ,Surgery ,Neurology (clinical) ,business ,030217 neurology & neurosurgery - Abstract
Background: Nocardia infection of the central nervous system leading to brain abscess is a rare condition but has a high mortality rate. Among the species of Nocardia, only three cases of brain abscess due to Nocardia asiatica infection have been reported. Case Description: A 65-year-old man with a history of autoimmune hemolytic anemia treated with prednisolone presented to our hospital because of occipital headache. Brain magnetic resonance imaging showed bilateral occipital lesions. The patient underwent craniotomy and resection of the left occipital lobe lesion. N. asiatica was identified by 16S rRNA sequencing of the resected specimen. Treatment with trimethoprim/sulfamethoxazole led to a complete resolution of the brain lesion. Conclusion: Because of the different antimicrobial sensitivity patterns among Nocardia species, both appropriate subtyping and susceptibility testing of uncommon species such as N. asiatica are required for the successful treatment of nocardial infections.
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- 2016
10. Neurofibromatosis Type 1-Associated Extracranial Vertebral Artery Aneurysm Complicated by Vertebral Arteriovenous Fistula After Rupture: Case Report and Literature Review
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Kenta Suzuki, Kimihiro Yoshino, Masatoshi Yunoki, Koji Hirashita, Atsuhito Uneda, and Shuichi Okubo
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Adult ,congenital, hereditary, and neonatal diseases and abnormalities ,medicine.medical_specialty ,Neurofibromatosis 1 ,Computed Tomography Angiography ,Vertebral artery ,Arteriovenous fistula ,Aneurysm, Ruptured ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,Hematoma ,medicine.artery ,medicine ,Humans ,cardiovascular diseases ,Neurofibromatosis ,Vertebral Artery ,Computed tomography angiography ,medicine.diagnostic_test ,business.industry ,medicine.disease ,Hemothorax ,Embolization, Therapeutic ,Surgery ,Angiography ,Arteriovenous Fistula ,cardiovascular system ,Female ,Neurology (clinical) ,Radiology ,business ,030217 neurology & neurosurgery - Abstract
Background Extracranial vertebral artery aneurysm related to neurofibromatosis type 1 (NF1) is rare. Aneurysmal rupture typically induces such symptoms as cervical hematoma, hemothorax, and hypotension. Here we report a case of ruptured extracranial vertebral artery aneurysm in a patient with NF1 who, rather than cervical hematoma, hemothorax, or hypotension, developed a vertebral arteriovenous fistula (AVF) after aneurysm rupture. Case Description A 35-year-old woman with a family history of NF1 presented with sudden-onset right neck and shoulder pain. Computed tomography angiography showed a right extracranial vertebral artery aneurysm. She had neither a cervical hematoma nor hypotension; however, angiography showed an AVF secondary to aneurysmal rupture. The patient was treated with endovascular coil embolization to prevent re-rupture. Postoperatively, her right neck and shoulder pain improved, and she was discharged without further neurologic deficits. Conclusions This patient's clinical course suggests that if there is minimal bleeding from an NF1-associated ruptured extracranial vertebral artery aneurysm, then typical symptoms, such as cervical hematoma, hemothorax, and hypotension, may be absent. Thus, ruptured extracranial vertebral artery aneurysm should be considered in the differential diagnosis of patients with NF1 with sudden-onset radiculopathy, even in the absence of typical symptoms. The detection of a vertebral AVF provides a useful clue to the diagnosis of aneurysm rupture in such cases.
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- 2016
11. Temperature distributions of electron beam-irradiated samples by scanning electron microscopy
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Takahisa Yamamoto, Katsuhiro Sasaki, T. Sudo, Tomoharu Tokunaga, Shuichi Okubo, S. Komatsubara, Tetsu Yonezawa, and Takashi Narushima
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Electron beam irradiation ,Histology ,Thermal conductivity ,Scanning electron microscope ,Chemistry ,Thermal ,Cathode ray ,Analytical chemistry ,Irradiation ,Temperature measurement ,Pathology and Forensic Medicine - Abstract
Summary An electron beam (EB) generated by a scanning electron microscope (SEM) was used to irradiate two samples having different thermal conductivities, and the resulting temperatures of the EB-irradiated areas as well as the temperature distributions within the samples were then measured using a thermal camera. These measurements showed overall increases in sample temperatures, as well as revealed temperature rises at the EB-irradiated areas that had little difference with one of the theoretical predictions. Differences between the actual and the predicted temperature measurements were analysed in terms of the accuracy with which parameters could be estimated. The temperature distributions of the samples were measured and, On the basis of the results, it was hypothesized that the temperature differential over an irradiated sample will be inversely correlated with its thermal conductivity.
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- 2012
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12. A method for accurate temperature measurement using infrared thermal camera
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Takahisa Yamamoto, Shigeyuki Komatsubara, Tetsu Yonezawa, Tomoharu Tokunaga, Shuichi Okubo, Takayuki Sudo, Takashi Narushima, and Katsuhiro Sasaki
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Materials science ,Infrared ,business.industry ,chemistry.chemical_element ,Edge (geometry) ,Temperature measurement ,Optics ,chemistry ,Molybdenum ,Thermal ,Stage (hydrology) ,business ,Instrumentation ,FOIL method - Abstract
The temperature distribution on a centre-holed thin foil of molybdenum, used as a sample and heated using a sample-heating holder for electron microscopy, was measured using an infrared thermal camera. The temperature on the heated foil area located near the heating stage of the heating holder is almost equal to the temperature on the heating stage. However, during the measurement of the temperature at the edge of the hole of the foil located farthest from the heating stage, a drop in temperature should be taken into consideration; however, so far, no method has been developed to locally measure the temperature distribution on the heated sample. In this study, a method for the accurate measurement of temperature distribution on heated samples for electron microscopy is discussed.
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- 2012
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13. Use of PET in the diagnosis of primary CNS lymphoma in patients with atypical MR findings
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Yuka Yamamoto, Yoshihiro Nishiyama, Yukito Maeda, Keisuke Miyake, Nobuyuki Kawai, Shuichi Okubo, and Takashi Tamiya
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Adult ,Male ,Pathology ,medicine.medical_specialty ,Lymphoma ,Central Nervous System Neoplasms ,Lesion ,Methionine ,Primary CNS Lymphoma ,Fluorodeoxyglucose F18 ,hemic and lymphatic diseases ,Humans ,Medicine ,Radiology, Nuclear Medicine and imaging ,In patient ,Aged ,Retrospective Studies ,Fluorodeoxyglucose ,medicine.diagnostic_test ,business.industry ,Primary central nervous system lymphoma ,Magnetic resonance imaging ,Retrospective cohort study ,General Medicine ,Middle Aged ,medicine.disease ,Magnetic Resonance Imaging ,Positron emission tomography ,Positron-Emission Tomography ,Female ,Radiology ,medicine.symptom ,business ,medicine.drug - Abstract
The diagnosis of primary central nervous system lymphoma (PCNSL) in immunocompetent patients with atypical magnetic resonance (MR) findings such as disseminated lesions or no (non-enhancing) lesion is sometimes difficult because of mimicking other tumorous and non-tumorous diseases. Positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) and (11)C-methionine (MET) can measure the glucose and amino acid metabolism in the lesions and may provide useful information for diagnosing PCNSL in patients with such subtle MR findings.We performed PET studies with FDG and MET in 17 histologically proven PCNSL and compared the uptake of FDG and MET qualitatively and quantitatively in the tumors between 12 typical and 5 atypical MR findings.All typical PCNSL showed strong uptake of FDG and MET; however, visual analysis of FDG and MET uptake in atypical PCNSL was not very useful for finding lesions in the brain. Semiquantitative FDG and MET uptake values (SUVmax) and quantitative FDG influx rate constant (K ( i )) in the tumors are significantly lower in atypical PCNSL compared with those in typical PCNSL. These values obtained in the lesions with atypical MR findings were also not useful for differentiating PCNSL from other tumorous and non-tumorous diseases. The k (3) values evaluated by FDG kinetic analysis in atypical PCNSL were similar to those obtained in typical PCNSL.Visual analysis of FDG and MET uptake in atypical PCNSL was not useful for finding the lesions in the brain. Semiquantitative and quantitative values obtained in the lesions with atypical MR findings were also not useful for differentiating PCNSL from other tumorous and non-tumorous diseases. The k (3) values evaluated by FDG kinetic analysis in atypical PCNSL may provide valuable information in the diagnosis of PCNSL.
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- 2010
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14. The Effect of Gender on Acute Hydrocephalus after Experimental Subarachnoid Hemorrhage
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Shuichi Okubo, Hajime Shishido, Guohua Xi, Richard F. Keep, Haining Zhang, and Ya Hua
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medicine.medical_specialty ,Subarachnoid hemorrhage ,medicine.diagnostic_test ,business.industry ,Mortality rate ,Perforation (oil well) ,Magnetic resonance imaging ,030204 cardiovascular system & hematology ,medicine.disease ,nervous system diseases ,Hydrocephalus ,03 medical and health sciences ,0302 clinical medicine ,medicine.anatomical_structure ,Ventricle ,Internal medicine ,Cerebral ventricle ,medicine ,Cardiology ,cardiovascular diseases ,Complication ,business ,030217 neurology & neurosurgery - Abstract
Acute hydrocephalus is a common complication of subarachnoid hemorrhage (SAH). We investigated the effect of gender on acute hydrocephalus development in a rat SAH model. SAH was induced in adult male and female Sprague-Dawley rats using endovascular perforation. Sham rats underwent the same procedure without perforation. Magnetic resonance imaging (MRI) was performed 24 h after SAH to determine ventricular volume. Hydrocephalus was defined as a ventricular volume that was more than 3 standard deviations from the mean value in sham-operated animals. After MRI, animals were euthanized and the extent of SAH was assessed using a modified grading system. No sham animals died. Mortality rates after SAH induction in male and female animals were 27 and 22 %, respectively. SAH induced significant ventricular enlargement compared with sham-operated rats (p < 0.01). The T2* hypointensity volume in the ventricle (used to assess intraventricular blood) was correlated with ventricular volume after SAH (r = 0.33, p < 0.05). The incidence of acute hydrocephalus 24 h after SAH was greater in female (75 %) than in male animals (47 %, p < 0.05) and the relative changes in ventricular volume were significantly larger in female than in male rats (292 ± 150 % vs 216 ± 127 % of sham-operated animals, respectively, p < 0.05). The increased hydrocephalus occurred even though SAH severity grade and ventricular T2* hypointensity volumes were not significantly different between male and female animals. Our data demonstrate that gender influences acute hydrocephalus development in a rat SAH model. Future studies should determine the role of estrogen in SAH-induced hydrocephalus.
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- 2016
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15. [A Patient with Advanced Gastric Cancer who Underwent Emergency Stenting for Carotid Artery Stenosis]
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Atsushi, Matsumoto, Ayumi, Nishida, Atsuhito, Uneda, Toshihiko, Shimizu, Shuichi, Okubo, Koji, Hirashita, Masatoshi, Yunoki, and Kimihiro, Yoshino
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Male ,Emergency Medical Services ,Fatal Outcome ,Stomach Neoplasms ,Liver Neoplasms ,Humans ,Carotid Stenosis ,Stents ,Aged - Abstract
We report the case of a patient with advanced gastric cancer who underwent emergency stenting for carotid artery stenosis that was causing fluctuating symptoms of cerebral ischemic stroke. A 66-year-old man presented with transient dysarthria and right hemifacial palsy. Examination revealed left internal carotid artery stenosis, as well as anemia caused by advanced gastric cancer. The man was treated on an outpatient basis using antiplatelet medication and anti-cancer therapy. Two months later, he developed recurrent ischemic stroke;because of this progression, a stent was placed in the carotid artery. After surgery, the cerebral ischemia resolved and did not recur before his death 6 months later. In conclusion, surgical intervention is a viable treatment option for internal carotid artery stenosis in cancer patients whose general health status is good.
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- 2015
16. The Effect of Gender on Acute Hydrocephalus after Experimental Subarachnoid Hemorrhage
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Hajime, Shishido, Haining, Zhang, Shuichi, Okubo, Ya, Hua, Richard F, Keep, and Guohua, Xi
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Male ,Behavior, Animal ,Endovascular Procedures ,Punctures ,Subarachnoid Hemorrhage ,Magnetic Resonance Imaging ,Cerebral Ventricles ,Rats ,Rats, Sprague-Dawley ,Disease Models, Animal ,Sex Factors ,Animals ,Female ,Hydrocephalus - Abstract
Acute hydrocephalus is a common complication of subarachnoid hemorrhage (SAH). We investigated the effect of gender on acute hydrocephalus development in a rat SAH model. SAH was induced in adult male and female Sprague-Dawley rats using endovascular perforation. Sham rats underwent the same procedure without perforation. Magnetic resonance imaging (MRI) was performed 24 h after SAH to determine ventricular volume. Hydrocephalus was defined as a ventricular volume that was more than 3 standard deviations from the mean value in sham-operated animals. After MRI, animals were euthanized and the extent of SAH was assessed using a modified grading system. No sham animals died. Mortality rates after SAH induction in male and female animals were 27 and 22 %, respectively. SAH induced significant ventricular enlargement compared with sham-operated rats (p 0.01). The T2* hypointensity volume in the ventricle (used to assess intraventricular blood) was correlated with ventricular volume after SAH (r = 0.33, p 0.05). The incidence of acute hydrocephalus 24 h after SAH was greater in female (75 %) than in male animals (47 %, p 0.05) and the relative changes in ventricular volume were significantly larger in female than in male rats (292 ± 150 % vs 216 ± 127 % of sham-operated animals, respectively, p 0.05). The increased hydrocephalus occurred even though SAH severity grade and ventricular T2* hypointensity volumes were not significantly different between male and female animals. Our data demonstrate that gender influences acute hydrocephalus development in a rat SAH model. Future studies should determine the role of estrogen in SAH-induced hydrocephalus.
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- 2015
17. Basal Ganglia Damage in Experimental Subarachnoid Hemorrhage
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Haining, Zhang, Shuichi, Okubo, Ya, Hua, Richard F, Keep, and Guohua, Xi
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Male ,Dopamine and cAMP-Regulated Phosphoprotein 32 ,Behavior, Animal ,Dopamine ,Blotting, Western ,Endovascular Procedures ,Brain ,Organ Size ,Punctures ,Subarachnoid Hemorrhage ,Immunohistochemistry ,Magnetic Resonance Imaging ,Severity of Illness Index ,Basal Ganglia ,Rats ,Rats, Sprague-Dawley ,Disease Models, Animal ,Basal Ganglia Diseases ,Blood-Brain Barrier ,Albumins ,Animals ,Hydrocephalus - Abstract
Research suggests that early brain injury following subarachnoid hemorrhage (SAH) is a primary therapeutic target, and early SAH-induced basal ganglia injury is not well studied. The present study examined basal ganglia injury in a rat model of SAH. Adult male Sprague-Dawley rats (n = 78) weighing 275-300 g underwent endovascular perforation to mimic aneurysmal SAH. Sham rats (n = 12) underwent the same procedure but without perforation. Magnetic resonance imaging (T2 MRI) was performed at 24 h after SAH to measure ventricle volumes and brain T2 lesion. Hydrocephalus in SAH rats was defined as a ventricular volume greater than three standard deviations above that in shams. Western blotting and immunochemistry were utilized to assess basal ganglia damage. Sixty rats survived the SAH and 40 % of those animals had T2 lesions in the basal ganglia. Twenty-six SAH rats had hydrocephalus. Rats with hydrocephalus had higher incidence of basal ganglia lesion (69 vs. 18 % in rats without hydrocephalus; p 0.01). Basal ganglia neuronal injury was also determined by examining the levels of dopamine- and cAMP-regulated phosphoprotein, Mr 32 kDa (DARPP-32). We found that rats with hydrocephalus had more severe basal ganglia injury with greater DARPP-32 depletion (DARPP-32/beta-actin: 0.38 ± 0.32 vs. 0.86 ± 0.45 in rats without hydrocephalus and 1.10 ± 0.28 in sham, p 0.05). In conclusion, SAH resulted in severe basal ganglia damage, which is associated with hydrocephalus development.
- Published
- 2015
18. A Feasibility Study for Characterizing Subsurface Faults and Hydrogeological Information with Marine Electromagnetic Prospecting
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Kimitaka Yoshimura, Kazunobu Yamane, and Shuichi Okubo
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Global and Planetary Change ,Hydrogeology ,Electromagnetics ,Geography, Planning and Development ,Geology ,High-level waste ,Waves and shallow water ,Geophysics ,Mining engineering ,Magnetotellurics ,Prospecting ,Groundwater ,Seabed ,Earth-Surface Processes - Abstract
This paper discusses characterizing and validating potential sites for high level radioactive waste disposal along the coastal areas using newly developed geophysical prospecting tools. The specific objective of this paper is to develop an electromagnetic (EM) technology for investigating the subsurface to the depths of 1, 000 m below the seafloor in the near-shore environment. The depth to the sea floor is up to 200 m. Characterization and validation of a site for high level radioactive waste disposal require a detailed knowledge of both the geological structures and the groundwater characteristics. The commercial as well as research-based marine controlled-source and natural-source EM technologies are available, however, there has been little work done in shallow water depths environment using such technologies. Here, we report the state-of-the-art EM method with applications to coastal areas with shallow water depths environment. Marine EM instrument developed is appropriate for investigating shallow water environment near coastal area. The interpretational technology for EM data is focused on 3-D magnetotelluric (MT) and 2.5-D controlled-source electromagnetics (CSEM). This paper demonstrates the performance of the new type of instrument and software, and the field experiment that was carried out in the Monterey Bay of California, USA, in 2003 and 2004. Additionally, we demonstrate interpretation techniques applied to characterizing groundwater using MT3-D result of Horonobe, Hokkaido.
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- 2006
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19. Spinal Fractures in Ankylosing Spinal Hyperostosis—A Report of Four Cases
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Hisanori Ikuma, Masatoshi Yunoki, Atsushi Matsumoto, Koji Hirashita, Atsuhito Uneda, Shuichi Okubo, and Kimihiro Yoshino
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Hyperostosis ,medicine.medical_specialty ,business.industry ,Medicine ,Radiology ,business ,medicine.disease - Published
- 2014
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20. Analytical expression of leakage current through double quantum dots in Pauli spin blockade
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Mikio Eto, Kosuke Saito, and Shuichi Okubo
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Physics ,Zeeman effect ,Condensed matter physics ,Energy level splitting ,Electron ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,symbols.namesake ,Pauli exclusion principle ,Quantum dot ,symbols ,Spin (physics) ,Hyperfine structure ,Quantum tunnelling - Abstract
We theoretically examine a small current through double quantum dots with Pauli spin blockade, in which electrons cannot be transported without spin–flip or higher-order tunnel processes (cotunneling). Analytical expressions for the current are given in both cases of sequential tunneling and resonant tunneling between the quantum dots and leads. In the former case, the cotunneling weakens the spin blockade and increases a coherent component of the current. When the cotunneling can be disregarded, effective magnetic fields created by nuclear spins (Overhauser fields) can be detected by the observation of the current. In the case of resonant tunneling with Zeeman splitting in an external magnetic field ( ∼ 1 T ) , small Overhauser fields ( ∼ 5 mT ) could be detected by the fine tuning of the resonant condition.
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- 2008
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21. Cerebral hemorrhage, brain edema, and heme oxygenase-1 expression after experimental traumatic brain injury
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Shuichi, Okubo, Guohua, Xi, Richard F, Keep, Karin M, Muraszko, and Ya, Hua
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Male ,Rats, Sprague-Dawley ,Disease Models, Animal ,Brain Injuries ,Animals ,Brain Edema ,Functional Laterality ,Gene Expression Regulation, Enzymologic ,Heme Oxygenase-1 ,Cerebral Hemorrhage ,Rats - Abstract
Intracranial bleeding is a common and serious consequence of traumatic brain injury (TBI). In the present study, we investigated cerebral hematoma occurrence, brain edema formation, blood-brain barrier (BBB) disruption, and heme oxygenase-1 (HO-1) expression after TBI. Moderate severity (1.8-2.2 atmospheres [ATM]) TBI was induced by lateral fluid percussion in male adult Sprague-Dawley rats. Sham rats underwent only a craniotomy. Rats were euthanized 24 h later for brain histology and immunoblotting analysis. We found TBI-induced cerebral hematomas and iron deposition in the ipsilateral hemisphere in all rats. TBI also caused marked BBB disruption (p0.05) and brain swelling (p0.05). HO-1, a key enzyme for heme degradation, was upregulated significantly after TBI (419 ± 89 vs 194 ± 59 pixels in the sham, p0.05). These results suggest that cerebral hematomas might play a role in brain injury after TBI. Future studies should determine the role of iron released from the cerebral hematoma in TBI.
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- 2013
22. Optimum structures for gamma-ray radiation resistant SiC-MOSFETs
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Yasuto Hijikata, Takeshi Ohshima, Toru Yoshie, Shinobu Onoda, Mikio Kandori, Takahiro Makino, Satoshi Mitomo, Yuki Tanaka, Takashi Yokoseki, Akinori Takeyama, Takuma Matsuda, Shuichi Okubo, and Koichi Murata
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010302 applied physics ,Materials science ,Radiation resistant ,business.industry ,020502 materials ,Gamma ray ,02 engineering and technology ,Surfaces and Interfaces ,Condensed Matter Physics ,01 natural sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,0205 materials engineering ,0103 physical sciences ,MOSFET ,Materials Chemistry ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Radiation resistance - Published
- 2017
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23. Cerebral Hemorrhage, Brain Edema, and Heme Oxygenase-1 Expression After Experimental Traumatic Brain Injury
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Ya Hua, Shuichi Okubo, Richard F. Keep, Karin M. Muraszko, and Guohua Xi
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Pathology ,medicine.medical_specialty ,Future studies ,Traumatic brain injury ,Brain edema ,business.industry ,medicine.medical_treatment ,Histology ,medicine.disease ,nervous system diseases ,Heme oxygenase ,Heme degradation ,chemistry.chemical_compound ,nervous system ,chemistry ,medicine ,business ,Heme ,Craniotomy - Abstract
Intracranial bleeding is a common and serious consequence of traumatic brain injury (TBI). In the present study, we investigated cerebral hematoma occurrence, brain edema formation, blood–brain barrier (BBB) disruption, and heme oxygenase-1 (HO-1) expression after TBI. Moderate severity (1.8–2.2 atmospheres [ATM]) TBI was induced by lateral fluid percussion in male adult Sprague–Dawley rats. Sham rats underwent only a craniotomy. Rats were euthanized 24 h later for brain histology and immunoblotting analysis. We found TBI-induced cerebral hematomas and iron deposition in the ipsilateral hemisphere in all rats. TBI also caused marked BBB disruption (p < 0.05) and brain swelling (p < 0.05). HO-1, a key enzyme for heme degradation, was upregulated significantly after TBI (419 ± 89 vs 194 ± 59 pixels in the sham, p < 0.05). These results suggest that cerebral hematomas might play a role in brain injury after TBI. Future studies should determine the role of iron released from the cerebral hematoma in TBI.
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- 2013
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24. Impacts of gate bias and its variation on gamma-ray irradiation resistance of SiC MOSFETs
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Mikio Kandori, Yuki Tanaka, Takeshi Ohshima, Shinobu Onoda, Takahiro Makino, Takuma Matsuda, Takashi Yokoseki, Koichi Murata, Akinori Takeyama, Toru Yoshie, Shuichi Okubo, Satoshi Mitomo, and Yasuto Hijikata
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010302 applied physics ,Materials science ,Negative-bias temperature instability ,010308 nuclear & particles physics ,Reverse short-channel effect ,business.industry ,Time-dependent gate oxide breakdown ,Surfaces and Interfaces ,Condensed Matter Physics ,01 natural sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Threshold voltage ,Carbide ,Gate oxide ,0103 physical sciences ,Materials Chemistry ,Optoelectronics ,Field-effect transistor ,Irradiation ,Electrical and Electronic Engineering ,business - Abstract
Gamma-ray irradiation into vertical type n-channel hexagonal (4H)-silicon carbide (SiC) metal-oxide-semiconductor field effect transistors (MOSFETs) was performed under various gate biases. The threshold voltage for the MOSFETs irradiated with a constant positive gate bias showed a large negative shift, and the shift slightly recovered above 100 kGy. For MOSFETs with non- and a negative constant biases, no significant change in threshold voltage, Vth, was observed up to 400 kGy. By changing the gate bias from positive bias to either negative or non-bias, the Vth significantly recovered from the large negative voltage shift induced by 50 kGy irradiation with positive gate bias after only 10 kGy irradiation with either negative or zero bias. It indicates that the positive charges generated in the gate oxide near the oxide–SiC interface due to irradiation were removed or recombined instantly by the irradiation under zero or negative biases.
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- 2016
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25. Improvement of radiation response of SiC MOSFETs under high temperature and humidity conditions
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Akinori Takeyama, Takashi Yokoseki, Shuichi Okubo, Shinobu Onoda, Yasuto Hijikata, Koichi Murata, Takuma Matsuda, Takeshi Ohshima, Mikio Kandori, Satoshi Mitomo, Takahiro Makino, Toru Yoshie, and Yuki Tanaka
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010302 applied physics ,Materials science ,General Engineering ,Oxide ,food and beverages ,General Physics and Astronomy ,Humidity ,02 engineering and technology ,Electron ,021001 nanoscience & nanotechnology ,01 natural sciences ,humanities ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,Silicon carbide ,Field-effect transistor ,Irradiation ,Composite material ,0210 nano-technology ,Voltage ,Leakage (electronics) - Abstract
The response of hexagonal (4H) silicon carbide (SiC) power metal–oxide–semiconductor field effect transistors (MOSFETs) to gamma-ray irradiation was investigated under elevated temperature and humid conditions. The shift in drain current–gate voltage (I D–V G) curves towards negative voltages and the leakage of I D with a current hump due to elevated temperature irradiation were suppressed under high humidity conditions relative to dry conditions. This result can be explained in terms of the reduction in trapped oxide charge and oxide–SiC interface traps generated by irradiation due to the humid conditions. In addition, during irradiation at elevated temperature in humid conditions, electron traps at the oxide–SiC interface obviously decrease at doses above 100 kGy.
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- 2016
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26. Abstract 3777: TAS4464, a novel and highly potent NEDD8 activating enzyme (NAE) inhibitor, causes apoptosis of sarcomas via cell cycle dysregulation
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Yoshikazu Iwasawa, Yayoi Fujioka, Takashi Mizutani, Hidenori Fujita, Teruhiro Utsugi, Shuichi Okubo, Kenichi Matsuo, Chihoko Yoshimura, Keiji Ishida, Shingo Tsuji, and Akihiro Hashimoto
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Cancer Research ,Programmed cell death ,Cell growth ,Cell cycle ,Biology ,NEDD8 ,Oncology ,Biochemistry ,Apoptosis ,Cancer cell ,medicine ,Cancer research ,Doxorubicin ,Neddylation ,medicine.drug - Abstract
Background Soft-tissue sarcomas (STSs) are heterogeneous tumors that comprise approximately 1% of adult cancers. Patients with advanced STS have a poor prognosis because few chemotherapy options are available. NAE catalyzes the first step in the NEDD8 conjugation (neddylation) pathway. Because it activates cullin-RING ligase complexes (CRLs) and thus is essential in cancer cell homeostasis, NAE is a promising target for cancer therapy. Here, we investigated the potency of the NAE inhibitor TAS4464 for various STS cell lines. Material and methods Cytotoxicity was evaluated through ATP-Based assay. The effects of TAS4464 on NEDD8 conjugation and CRL substrates were evaluated by Western analysis. Cell cycle progression was analyzed by using flow cytometry. Small interfering RNAs (siRNAs) were lipofected into a clear cell sarcoma (CCS) line (SU-CCS-1). The antitumor activity of intravenous TAS4464 was evaluated in xenograft models of the aforementioned CCS and 2 rhadomyosarcoma (RMS) lines (SJCRH30 and RD). Results TAS4464 suppressed cell growth and induced cell death in various STS cell lines at lower concentrations than did an investigational NAE inhibitor, MLN4924, and a conventional STS treatment agent, doxorubicin (DXR). Notably, the GI50 values of TAS4464 were less than 10 nM in the tested RMS and CCS cell lines. TAS4464 treatment led to the elimination of cullin neddylation, accumulation of CRL substrate proteins (CDT1, p27, and p21), S phase arrest, and ultimately apoptosis in these STS cell lines. Furthermore, knockdown of CRL substrate proteins by siRNAs markedly attenuated TAS4464-induced cytotoxicity in STS cells. These results suggest that TAS4464-induced cell death was triggered by cell cycle dysregulation based on accumulation of CRL substrate proteins following NAE inhibition. TAS4464 also led to a decrease in cullin neddylation and accumulation of CRL substrate proteins in RMS and CCS lines subcutaneous xenografts. Weekly administration of TAS4464 (100 mg/kg, IV) completely suppressed tumor growth in mice bearing subcutaneous RD and SJCRH30 xenografts. The effects of TAS4464 significantly exceeded that of DXR and MLN4924. Furthermore, TAS4464 induced tumor regression of ∼50% in the pazopanib, a drug approved for STS, insensitive SU-CCS-1 xenograft model. Conclusion TAS4464 prominently inhibited cell growth and induced apoptosis in RMS and CSC cells through cell cycle dysregulation and demonstrated impressive antitumor activities in STS xenograft models that respond poorly to DXR and pazopanib. Therefore, TAS4464 may become a valuable therapeutic option for patients with advanced STS. Citation Format: Hidenori Fujita, Yayoi Fujioka, Keiji Ishida, Chihoko Yoshimura, Akihiro Hashimoto, Shingo Tsuji, Takashi Mizutani, Shuichi Okubo, Kenichi Matsuo, Teruhiro Utsugi, Yoshikazu Iwasawa. TAS4464, a novel and highly potent NEDD8 activating enzyme (NAE) inhibitor, causes apoptosis of sarcomas via cell cycle dysregulation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3777.
- Published
- 2016
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27. Subarachnoid Hemorrhage-Induced Hydrocephalus in Rats
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Jennifer Strahle, Guohua Xi, Ya Hua, Richard F. Keep, and Shuichi Okubo
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Male ,Pathology ,medicine.medical_specialty ,Subarachnoid hemorrhage ,Perforation (oil well) ,Ventricular system ,Article ,Rats, Sprague-Dawley ,medicine ,Animals ,cardiovascular diseases ,Advanced and Specialized Nursing ,business.industry ,Histology ,Subarachnoid Hemorrhage ,medicine.disease ,nervous system diseases ,Hydrocephalus ,Rats ,Disease Models, Animal ,Acute hydrocephalus ,Immunohistochemistry ,Neurology (clinical) ,Cardiology and Cardiovascular Medicine ,Complication ,business - Abstract
Background and Purpose— Hydrocephalus is an important complication of subarachnoid hemorrhage (SAH). We investigated the occurrence of acute hydrocephalus in a rat SAH model. Methods— SAH was induced by endovascular perforation in adult male Sprague-Dawley rats (n=36). Sham rats (n=8) underwent the same procedure without perforation. MRI was performed 24 hours after SAH and the volume of the ventricular system and extent of T2* hypointensity lesions were measured. We defined hydrocephalus as ventricular volume > +3 SDs above the mean in sham animals. SAH grade was determined and brains were used for histology, immunohistochemistry, Perls staining, and Western blot analysis. Ventricular wall damage was defined as percentage of ependymal surface disruption. Results— All surviving rats (n=27) after SAH had ventricular enlargement (33.6±4.7 versus 13.5±1.4 mm 3 in sham animals, P r =0.48; P P P Conclusions— SAH causes ventricular enlargement in a rat endovascular perforation model, with hydrocephalus occurring in 44% of animals at 24 hours. Rats with hydrocephalus had more severe SAH, intraventricular hemorrhage, and greater ventricular wall damage.
- Published
- 2012
28. Natural products reveal cancer cell dependence on oxysterol-binding proteins
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Matthew D. Shair, D. Ryan Anderson, Shuichi Okubo, Minpei Kuroda, Kousei Shimada, Kevin C. Fortner, John A. Tallarico, David Schwalb, Jason Murphy, Yoshihiro Mimaki, Eugene C. Petrella, Markus Schirle, Kittikhun Wangkanont, Chikako Kikuchi, Ivan Cornella-Taracido, Anthony W. G. Burgett, and Thomas B. Poulsen
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Receptors, Steroid ,Biology ,Article ,Cell Line, Tumor ,Neoplasms ,Stilbenes ,Humans ,Spiro Compounds ,Molecular Biology ,OSBP ,Lipid Transport ,Cholestenones ,Cell Proliferation ,Biological Products ,Cell Biology ,Protein superfamily ,Saponins ,Lipid Metabolism ,Hydroxycholesterols ,Cell biology ,Sphingomyelins ,Oxysterol binding ,Biochemistry ,Cancer cell ,Phenazines ,Steroids ,Signal transduction ,Cephalostatin ,Oxysterol-binding protein ,Carrier Proteins ,Signal Transduction - Abstract
Cephalostatin 1, OSW-1, ritterazine B and schweinfurthin A are natural products that potently, and in some cases selectively, inhibit the growth of cultured human cancer cell lines. The cellular targets of these small molecules have yet to be identified. We have discovered that these molecules target oxysterol binding protein (OSBP) and its closest paralog, OSBP-related protein 4L (ORP4L)--proteins not known to be involved in cancer cell survival. OSBP and the ORPs constitute an evolutionarily conserved protein superfamily, members of which have been implicated in signal transduction, lipid transport and lipid metabolism. The functions of OSBP and the ORPs, however, remain largely enigmatic. Based on our findings, we have named the aforementioned natural products ORPphilins. Here we used ORPphilins to reveal new cellular activities of OSBP. The ORPphilins are powerful probes of OSBP and ORP4L that will be useful in uncovering their cellular functions and their roles in human diseases.
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- 2011
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29. Correlation of L-methyl-11C-methionine (MET) uptake with L-type amino acid transporter 1 in human gliomas
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Yoshihiro Nishiyama, Nobuyuki Kawai, Takashi Tamiya, Shuichi Okubo, Hai-Ning Zhen, and Reiji Haba
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Adult ,Male ,Cancer Research ,Pathology ,medicine.medical_specialty ,Adolescent ,Fusion Regulatory Protein 1, Heavy Chain ,Cell ,Standardized uptake value ,Antigens, CD34 ,Biology ,Astrocytoma ,Large Neutral Amino Acid-Transporter 1 ,Immunoenzyme Techniques ,chemistry.chemical_compound ,Young Adult ,Methionine ,Glioma ,Neutral amino acid transport ,medicine ,Humans ,Tissue Distribution ,Child ,Microvessel ,Aged ,Neoplasm Staging ,Aged, 80 and over ,Brain Neoplasms ,Brain ,Middle Aged ,medicine.disease ,Prognosis ,medicine.anatomical_structure ,Neurology ,Oncology ,chemistry ,Child, Preschool ,Microvessels ,Cancer research ,Immunohistochemistry ,Female ,Neurology (clinical) ,Endothelium, Vascular ,Immunostaining - Abstract
L-type amino acid transporter 1 (LAT1) is a neutral amino acid transport system and is a major route for the transport of large neutral amino acids, including methionine, through the plasma membrane. LAT1 requires the heavy chain of 4F2 cell surface antigen (4F2hc) for its functional expression. Positron emission tomography (PET) with L-[methyl-(11)C] methionine (MET) provides information about amino acid metabolism in brain tumors. We conducted a clinicopathologic study to elucidate the correlation of LAT1 and 4F2hc expression with MET uptake in patients with newly diagnosed human gliomas. Thirty-three newly diagnosed glioma patients were enrolled in this study. Uptake of MET in the tumor was evaluated with the maximum standardized uptake value (SUVmax). Expression of the LAT1, 4F2hc, and CD34, and Ki-67 labeling index of the tumor were analyzed by immunohistochemical staining, and the correlation with the SUVmax in the tumors was examined. Expression of LAT1 and 4F2hc was higher in high-grade gliomas than in low-grade gliomas. The grade of LAT1 immunostaining increased with glioma grade. LAT1 was mainly expressed in the tumor cytoplasm and vascular endothelium and 4F2hc was mainly expressed in the tumor cytoplasm and plasma membrane. Expression of LAT1 but not 4F2hc was significantly correlated with MET SUVmax. Expression of LAT1 in the tumor vascular endothelium is significantly correlated with CD34 positive microvessel density. In conclusion, MET SUVmax correlates with LAT1 expression in the tumor in newly diagnosed gliomas. MET transport may be increased by an increased number of microvessels combined with a higher density or activity of LAT1 in the tumor endothelial cells in high-grade gliomas. Use of MET-PET as a molecular target combined with anti-angiogenesis in glioma therapy should be addressed in future studies.
- Published
- 2009
30. Effect of high thoracic epidural anesthesia on ventilatory response to hypercapnea in normal volunteers
- Author
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Tadanobu Mizoguti, Masato Hagiya, Tetsuo Kochi, Hajime Morinari, and Shuichi Okubo
- Subjects
medicine.medical_specialty ,Normal volunteers ,Thoracic epidural ,business.industry ,Anesthesia ,medicine ,business ,Surgery - Published
- 1991
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31. Birth of a Submarine Volcano 'Teisi Knoll'
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Joyo Osaka, Shigeru Kato, Shuichi Okubo, Kazuki Watanabe, Kazuyoshi Kudo, Shoichi Oshima, and Masakazu Tsuchide
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geography ,Submarine eruption ,geography.geographical_feature_category ,Volcano ,Magma ,Phreatomagmatic eruption ,General Earth and Planetary Sciences ,Bathymetry ,Earthquake swarm ,Submarine volcano ,Geology ,Seafloor spreading ,Seismology - Abstract
Frequent sea bottom surveying in an area of earthquake swarms in Sagami Bay about 2 to 3km from the east coast of Izu Peninsula clearly disclosed the birth of a new submarine volcano and processes of its formation. Bathymetric soundings, taken on July 9, 1989, showed that the seafloor, where the new volcano was to be born, was characterized by undeformed sedimented bottom in depths of about 100m. Large-amplitude tremors, beginning on the evening of July 11, were associated with the formation of a new volcanic knoll (cryptodome). This was confirmed by the survey vessel "Takuyo" on July 13 at 18 h 28m when it was found that the knoll had risen 25m above the surrounding seafloor. Five minutes later, after the existence of this newly formed bulge was established, a submarine eruption from the knoll began. While escaping from the hazardous area, Takuyo took photographs and made video tape recordings of the effects of the eruption on the sea surface and in the atmosphere. In addition, audio records of a series of frightening acoustic shocks of the volcanic activity were made. These shocks suggest frequent discharges from the seafloor of high pressure gasses associated with sub-bottom phreatomagmatic eruptions. On July 15, an unmanned automated survey craft, the Manbou, recorded a column of gas bubbles rising from the 200m diameter crater in the center of the knoll. The eruption of July 13 had lowered the height of the dome from 25 to 10m. Three months later a detailed bathymetric survey, using a highly accurate multibeam sounding system, Hydrochart, confirmed the maar-like topography of the volcano and also recorded the weakened emission of gasses.
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- 1991
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32. Growth pattern of the early Pleistocene Higashihigasa submarine channel, Boso Peninsula, central Japan
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Takashi Mitsunashi, Shuichi Okubo, and Seiki Yamauchi
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geography ,Paleontology ,geography.geographical_feature_category ,Early Pleistocene ,Peninsula ,General Engineering ,General Earth and Planetary Sciences ,Submarine channel ,Geology ,Seismology ,General Environmental Science - Published
- 1990
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33. Radiation response of silicon carbide metal–oxide–semiconductor transistors in high dose region
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Shuichi Okubo, Takahiro Makino, Hiroshi Abe, Takeshi Ohshima, Mikio Kandori, Takuma Matsuda, Takashi Yokoseki, Toru Yoshie, Yuki Tanaka, Satoshi Mitomo, Yasuto Hijikata, Shinobu Onoda, and Koichi Murata
- Subjects
010302 applied physics ,Materials science ,010308 nuclear & particles physics ,Subthreshold conduction ,business.industry ,Transistor ,General Engineering ,General Physics and Astronomy ,01 natural sciences ,Threshold voltage ,law.invention ,Metal ,chemistry.chemical_compound ,chemistry ,law ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Silicon carbide ,Optoelectronics ,Field-effect transistor ,Irradiation ,business ,Voltage - Abstract
Radiation response of vertical structure hexagonal (4H) silicon carbide (SiC) power metal–oxide–semiconductor field effect transistors (MOSFETs) was investigated up to 5.8 MGy. The drain current–gate voltage curves for the MOSFETs shifted from positive to negative voltages due to irradiation. However, the drain current–gate voltage curve shifts for the MOSFETs irradiated at 150 °C was smaller than those irradiated at room temperature. Thus, the shift of threshold voltage due to irradiation was suppressed by irradiation at 150 °C. No significant change or slight decrease in subthreshold voltage swing for the MOSFETs irradiated at 150 °C was observed. The value of channel mobility increased due to irradiation, and the increase was enhanced by irradiation at 150 °C comparing to irradiation at RT.
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- 2015
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34. Structure-function analysis of NADE: identification of regions that mediate nerve growth factor-induced apoptosis
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Jun, Mukai, Shisako, Shoji, Makoto T, Kimura, Shuichi, Okubo, Hajime, Sano, Petro, Suvanto, Yin, Li, Shinji, Irie, and Taka-Aki, Sato
- Subjects
Protein Conformation ,Recombinant Fusion Proteins ,Amino Acid Motifs ,DNA Mutational Analysis ,Green Fluorescent Proteins ,Molecular Sequence Data ,Apoptosis ,Receptors, Nerve Growth Factor ,Transfection ,PC12 Cells ,Receptor, Nerve Growth Factor ,Adenoviridae ,Cell Line ,Mice ,Structure-Activity Relationship ,Leucine ,Two-Hybrid System Techniques ,In Situ Nick-End Labeling ,Animals ,Humans ,Point Mutation ,Amino Acid Sequence ,Genes, Dominant ,Models, Genetic ,Gene Transfer Techniques ,Proteins ,Immunohistochemistry ,Protein Structure, Tertiary ,Rats ,Luminescent Proteins ,Microscopy, Fluorescence ,Mutation ,Apoptosis Regulatory Proteins ,Signal Transduction ,Subcellular Fractions - Abstract
Nerve growth factor (NGF) can induce apoptosis in neural cells via activation of the low affinity neurotrophin receptor p75NTR. NADE (p75NTR-associated cell death executor) is a p75NTR-associated protein that mediates apoptosis in response to NGF by interacting with the death domain of p75NTR in 293T, PC12, and nnr5 cells (Mukai, J., Hachiya, T., Shoji-Hoshino, S., Kimura, M. T., Nadano, D., Suvanto, P., Hanaoka, T., Li, Y., Irie, S., Greene, L. A., and Sato, T. A. (2000) J. Biol. Chem. 275, 17566-17570). We performed extensive mutational analysis on NADE, to better characterize its structural and functional features. Truncation of a minimal region, including amino acid residues 41-71 of NADE, was found to be sufficient to induce apoptosis. The designated regulatory region includes the C-terminal amino acid residues (72-112) and is essential for NGF-dependent regulation of NADE-induced apoptosis. Furthermore, the mutants with amino acid substitutions in the leucine-rich nuclear export signal (NES) sequence (residues 90-100) abolished the export of NADE from the nucleus to the cytoplasm. Mutation of the NES also abolished self-association of NADE, its interaction with p75NTR, and NGF-dependent apoptosis. Expression of a fragment of NADE (amino acid residues 81-124) blocked NGF-induced apoptosis in oligodendrocytes, suggesting that this region has a dominant negative effect on NGF/p75NTR-induced apoptosis. These studies identify distinct regions of NADE that are involved in regulating specific functions involved in p75NTR signal transduction.
- Published
- 2002
35. Reduction of cross-erase in phase-change media
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Masayuki Kubogata, Mitsuya Okada, and Shuichi Okubo
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Micrometre ,Reduction (complexity) ,Phase change ,Materials science ,Optics ,business.industry ,Optical engineering ,Molar absorptivity ,business ,Pitch tracking ,Amorphous solid - Abstract
We developed a phase change media that has less cross-erase at a track pitch of less than 0.6 micrometer. The phase change media has an absorptivity ratio Ac/Aa of 1.5 (Ac:absorptivity in a crystalline state, Aa:absorptivity in an amorphous state), while maintaining the rapid cooling structure. There was no significant cross-erase even at a track pitch of 0.52 micrometer. Feasibility of recording capacity of about 5 GB on a 120 mm disk has been confirmed.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
- Published
- 1998
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36. Reduction of cross erase in phase change media
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Shuichi Okubo, Masayuki Kubogata, and Mitsuya Okada
- Abstract
The reduction of cross erase in phase change media is crucial to the achievement of land/groove recording with a track pitch of less than 0.6 μm. The method of cross erase reduction that we report here have succeeded without the use of deep groove substrates [1].
- Published
- 1998
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37. Control of ventilation in adult rats hypoxic in the neonatal period
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Jacopo P. Mortola and Shuichi Okubo
- Subjects
Aging ,Physiology ,Peripheral chemoreceptors ,Blood Pressure ,Biology ,Physiology (medical) ,Hyperventilation ,Heart rate ,Reflex ,medicine ,Animals ,Hypoxia ,Hyperoxia ,Myocardium ,Respiration ,Rats, Inbred Strains ,Organ Size ,Hypoxia (medical) ,Stimulation, Chemical ,Rats ,Blood pressure ,Animals, Newborn ,Control of respiration ,Anesthesia ,medicine.symptom ,Hypercapnia - Abstract
Three groups of 50-day-old (i.e., postpuberty) rats have been studied: controls, rats exposed to 6 days of hypoxia [inspired fraction of O2 (FIo2) = 10% O2] when newborn (Nb-Hypox), and rats exposed to the same level and duration of hypoxia after weaning (Ad-Hypox). Ventilation during normoxic breathing was higher in Nb-Hypox than in controls or Ad-Hypox. The ventilatory response to acute hypoxia (10 min of 10% O2) was about one-half in Nb-Hypox than in the other two groups. Additional measurements performed on Nb-Hypox and controls showed minimal or no differences between the two groups in the ventilatory responses to hyperoxia and hypercapnia, heart rate and blood pressure at various FIO2, and blood biochemistry. Analysis of the Hering-Breuer reflexes, during barbiturate anesthesia, suggested a decreased central inhibition on inspiratory activity in Nb-Hypox, which with a lower sensitivity to inputs from the peripheral chemoreceptors may contribute to the normoxic hyperventilation and the blunted response to acute hypoxia. The ventilatory patterns of Nb-Hypox rats bear numerous similarities with those of high-altitude natives and could suggest that the highlander's ventilatory responses are not genetic characteristics but relate to chronic hypoxia early in life.
- Published
- 1990
38. Multiple cerebral infarctions in a patient with idiopathic thrombocytopenic purpura.
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Masatoshi Yunoki, Kenta Suzuki, Atsuhito Uneda, Shuichi Okubo, Koji Hirashita, and Kimihiro Yoshino
- Subjects
IDIOPATHIC thrombocytopenic purpura - Abstract
The article presents a case study of 31-year-old woman who was diagnosed with multiple cerebral infarctions with idiopathic thrombocytopenic purpura.
- Published
- 2016
39. Control of ventilation in adult rats hypoxic in the neonatal period.
- Author
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SHUICHI OKUBO and MORTOLA, JACOPO P.
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- 1990
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40. Clinical spectrum and endomyocardial biopsy findings in eosinophilic heart disease
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Machiko Take, Koshichiro Hirosawa, Morie Sekiguchi, Shuichi Okubo, Michiaki Hiroe, Takanori Shirai, Hideaki Mizoguchi, Mikihiko Kijima, and Takeshi Ishide
- Subjects
Adult ,Male ,medicine.medical_specialty ,Myocarditis ,Adolescent ,Heart disease ,Biopsy ,Endomyocardial fibrosis ,Electrocardiography ,Pericarditis ,Internal medicine ,Eosinophilia ,Eosinophilic ,medicine ,Humans ,Endocarditis ,Aged ,Aged, 80 and over ,medicine.diagnostic_test ,business.industry ,Myocardium ,Middle Aged ,Endomyocardial Fibrosis ,medicine.disease ,Cardiac surgery ,Echocardiography ,Cardiology ,Female ,Cardiomyopathies ,Cardiology and Cardiovascular Medicine ,business ,Endocardium - Abstract
Fourteen cases of heart disease with hypereosinophilia were analyzed employing conventional cardiologic methods, including echocardiography, cardiac catheterization, and endomycoardial biopsy. The cases were divided into four types: (1) Acute carditic (endocarditis, myocarditis, pericarditis; five cases); (2) ventricular dilation (three cases); (3) restrictive (three cases); (4) electric disturbance (three cases). Biopsy revealed significant changes in all cases. In one case of the ventricular dilation type, endomyocardial fibrosis with myocardial degeneration was seen, and in another case mural thrombus formation was shown to be present. In three cases of the restrictive type, endomyocardial fibrosis (EMF) was observed. In two cases of the electric disturbance type, minor right ventricular myocardial degeneration was observed. In two of the three cases of the carditic type and in three of eight cases in other categories, postmyocarditic changes were observed. The course of the disease compared with the type of disorder revealed a short course in the carditic type and a longer course, ranging from 2 to 24 years, with one exception, in the other types. It is also confirmed that the various histopathologic changes can be related to particular clinical presentations. We have shown that the basic changes in eosinophilic heart disease are not restricted to the endomyocardium and that they occur in various parts of the heart causing more widespread manifestations. The more comprehensive term “eosinophilic heart diease” is a preferable description.
- Published
- 1985
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- View/download PDF
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