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MURATA YASUHIRO The Korean Astronomical Society 2005 Journal of The Korean Astronomical Society Vol.38 No.2
The first Space-VLBI project, VSOP, started successfully with the launch of the dedicated space-VLBI satellite HALCA in 1997. The project has been in scientific operation in the 1.6 GHz and 5 GHz bands, and studies have been done mainly of the jet phenomena related to active galactic nuclei. A second generation space- VLBI project, VSOP-2, has been planned by the working group formed at ISAS/JAXA with many collaborators. The spacecraft is planned to observe in the 8, 22 and 43 GHz bands with cooled receivers for the two higher bands, and with a maximum angular resolution at 43 GHz (7 mm) of about 40 micro-arcseconds. The VSOP-2 satellite will also have the capability of the phase-reference and full polarization observations, which will produce more powerful results than those of the VSOP project. Far-future space-VLBI projects following VSOP and VSOP-2, have a large potential to achieve enough resolution and sensitivity to satisfy astronomers in future.
( Yasuhiro Morita ),( Shigeki Bamba ),( Osamu Inatomi ),( Kenichiro Takahashi ),( Takayuki Imai ),( Masaki Murata ),( Masashi Ohno ),( Masaya Sasaki ),( Tomoyuki Tsujikawa ),( Akira Andoh ) 대한장연구학회 2020 Intestinal Research Vol.18 No.2
Background/Aims: We retrospectively analyzed Crohn’s disease (CD) patients with small intestinal strictures who underwent single-balloon enteroscopy (SBE) to ascertain whether prototype SBEs with a passive bending mechanism and high force transmission insertion tube had better insertability in the small intestine than a conventional SBE. Methods: Among 253 CD patients who underwent SBE, we identified 94 CD patients who had undergone attempted endoscopic balloon dilatation (EBD) for small intestinal stenosis for inclusion in this study. We analyzed whether the type of scope used for their initial procedure affected the cumulative surgery-free rate. For the insertability analysis, patients who underwent SBE at least twice were divided into 3 groups according to the type of scope used: conventional SBE only, prototype SBE only, and both conventional and prototype SBEs. For each group, depth of insertion, procedure time, and number of EBDs were compared in the same patient at different time points. Results: The success rate of EBD was 88.3%. The 5- and 10-year cumulative surgery-free rate was 75.7% and 72.8%, respectively. Cox regression analysis indicated that the factors contributing to surgery were long stricture (≥2 cm), EBD failure, and elevated Crohn’s Disease Activity Index, but not the type of scope used for EBD. The prototype SBEs significantly improved the depth of insertion (P=0.03, Wilcoxon’s signed-rank test). Conclusions: In CD patients with small intestinal stenosis, the prototype SBEs with a passive bending mechanism and high force transmission insertion tube did not improve long-term EBD outcome but did improve deep insertability. (Clinical Trial Registration No. UMIN000037102) (Intest Res 2020;18:229-237)
Yozo Sato,Shohei Chatani,Takaaki Hasegawa,Shinichi Murata,Takamichi Kuwahara,Kazuo Hara,Yasuhiro Shimizu,Yoshitaka Inaba 소화기인터벤션의학회 2021 Gastrointestinal Intervention Vol.10 No.1
Background: Malignant afferent loop syndrome occurs after biliary reconstruction and is difficult to treat because of the complicated anatomical changes. The aim of this study was to investigate the safety and efficacy of percutaneous metallic stent placement for malignant afferent loop syndrome via the blind end of the jejunal limb after biliary reconstruction. Methods: Percutaneous metallic stent placement via the jejunal limb was performed in five male patients (median age, 68 years; range, 51–88 years) with malignant afferent loop syndrome following pancreatoduodenectomy or bile duct resection with reconstruction at our institute from June 2009 to April 2019. Reconstruction was performed using a modified Child’s method or the Roux-en-Y method, and blind end of the jejunal limb was surgically fixed to the abdominal wall. Percutaneous drainage of the afferent loop was performed via the blind end of the jejunal limb. Subsequently, percutaneous metallic stent placement was performed via the same route. Technical success, clinical success, and complications were retrospectively evaluated. Results: Percutaneous metallic stent placement via the blind end of the jejunal limb was successfully achieved in all six procedures. Additional metallic stent placement was performed due to tumor ingrowth in a patient. Drainage catheters were removed from three patients, clamped in one, and could not be removed in one. Clinical success was achieved in four patients (80%) without major complications. Conclusion: Percutaneous metallic stent placement for malignant afferent loop syndrome via the blind end of the jejunal limb after biliary reconstruction could be a safe and effective procedure.
Yozo Sato,Shohei Chatani,Takaaki Hasegawa,Shinichi Murata,Takamichi Kuwahara,Kazuo Hara,Yasuhiro Shimizu,Yoshitaka Inaba 소화기인터벤션의학회 2021 International journal of gastrointestinal interven Vol.10 No.1
Background: Malignant afferent loop syndrome occurs after biliary reconstruction and is difficult to treat because of the complicated anatomical changes. The aim of this study was to investigate the safety and efficacy of percutaneous metallic stent placement for malignant afferent loop syndrome via the blind end of the jejunal limb after biliary reconstruction. Methods: Percutaneous metallic stent placement via the jejunal limb was performed in five male patients (median age, 68 years; range, 51–88 years) with malignant afferent loop syndrome following pancreatoduodenectomy or bile duct resection with reconstruction at our institute from June 2009 to April 2019. Reconstruction was performed using a modified Child’s method or the Roux-en-Y method, and blind end of the jejunal limb was surgically fixed to the abdominal wall. Percutaneous drainage of the afferent loop was performed via the blind end of the jejunal limb. Subsequently, percutaneous metallic stent placement was performed via the same route. Technical success, clinical success, and complications were retrospectively evaluated. Results: Percutaneous metallic stent placement via the blind end of the jejunal limb was successfully achieved in all six procedures. Additional metallic stent placement was performed due to tumor ingrowth in a patient. Drainage catheters were removed from three patients, clamped in one, and could not be removed in one. Clinical success was achieved in four patients (80%) without major complications. Conclusion: Percutaneous metallic stent placement for malignant afferent loop syndrome via the blind end of the jejunal limb after biliary reconstruction could be a safe and effective procedure.
Shohei Chatani,Yozo Sato,Nozomi Okuno,Takaaki Hasegawa,Shinichi Murata,Hidekazu Yamaura,Kazuo Hara,Yasuhiro Shimizu,Yoshitaka Inaba 소화기인터벤션의학회 2021 International journal of gastrointestinal interven Vol.10 No.2
Left-sided portal hypertension following pancreaticoduodenectomy (PD) with portal vein resection and splenic vein ligation may cause ectopic variceal formation, potentially resulting in life-threatening bleeding. We report of a 79-year-old male suffering from severe anemia and melena after PD. Emergency endoscopy and contrast-enhanced computed tomography (CECT) revealed ectopic varices at the anastomosis site of pancreaticojejunostomy. An interventional radiology approach was preferred over surgical and endoscopic treatment because of the poor general condition and altered anatomy. In the first procedure, percutaneous transhepatic retrograde obliteration was performed using the coaxial double balloon-occlusion technique. Although hemostasis was obtained, re-bleeding occurred two months later. CECT revealed the development of another collateral pathway and the recurrence of varices. Insufficient embolization of the afferent vein was considered the cause of recurrence. Therefore, a percutaneous transsplenic approach was used, and complete embolization of varices was achieved. When transhepatic retrograde obliteration is not effective, transsplenic antegrade obliteration can be a useful therapeutic option.
Shohei Chatani,Yozo Sato,Nozomi Okuno,Takaaki Hasegawa,Shinichi Murata,Hidekazu Yamaura,Kazuo Hara,Yasuhiro Shimizu,Yoshitaka Inaba 소화기인터벤션의학회 2021 Gastrointestinal Intervention Vol.10 No.2
Left-sided portal hypertension following pancreaticoduodenectomy (PD) with portal vein resection and splenic vein ligation may cause ectopic variceal formation, potentially resulting in life-threatening bleeding. We report of a 79-year-old male suffering from severe anemia and melena after PD. Emergency endoscopy and contrast-enhanced computed tomography (CECT) revealed ectopic varices at the anastomosis site of pancreaticojejunostomy. An interventional radiology approach was preferred over surgical and endoscopic treatment because of the poor general condition and altered anatomy. In the first procedure, percutaneous transhepatic retrograde obliteration was performed using the coaxial double balloon-occlusion technique. Although hemostasis was obtained, re-bleeding occurred two months later. CECT revealed the development of another collateral pathway and the recurrence of varices. Insufficient embolization of the afferent vein was considered the cause of recurrence. Therefore, a percutaneous transsplenic approach was used, and complete embolization of varices was achieved. When transhepatic retrograde obliteration is not effective, transsplenic antegrade obliteration can be a useful therapeutic option.
Intraday Variability Feature and Milliarcsecond-Scale Structure in PKS 1622-297
Kiyoaki Wajima,Hayley E. Bignall,Hideyuki Kobayashi,Hisashi Hirabayashi,Kenta Fujisawa,Masato Tsuboi,Philip G. Edwards,Yasuhiro Murata 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4
PKS 1622.297 is the most luminous gamma-ray emitting active galactic nucleus (AGN) ever detected and shows a gamma-ray intraday variability (IDV). We made a high-resolution space very long baseline interferometry (VLBI) observation of the source almost three years after the gammaray IDV. The source shows a compact core-jet structure, and all jet components have an apparent superluminal motion up to 12 h.1c. As an alternative probe of the sub-parsec scale structure, we also present the results from multi-epoch Australia Telescope Compact Array (ATCA) total flux monitoring, which indicate the presence of IDV. We examine the inner structure of the gamma-ray emitting AGN in light of these observations.