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Dive into the research topics where Atsushi Imamura is active.

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Featured researches published by Atsushi Imamura.


Thrombosis Research | 2000

Platelet-Derived Microparticles in Patients with Arteriosclerosis Obliterans: Enhancement of High Shear-Induced Microparticle Generation by Cytokines

Shosaku Nomura; Atsushi Imamura; Masashi Okuno; Yasuo Kamiyama; Yoshihiro Fujimura; Yasuo Ikeda; Shirou Fukuhara

We evaluated the plasma concentrations of cytokines and platelet-derived microparticles in patients with arteriosclerosis obliterans and studied the effect of cytokines on platelet-derived microparticle generation under high shear stress. Interleukin-6 levels peaked at 48 hours after vascular surgery, while thrombopoietin started to increase at 24 to 48 hours postoperatively and peaked on the seventh day. Platelet activation markers were increased in the arteriosclerosis obliterans patients preoperatively. Levels of P-selectin and CD63 both increased further, peaking at 6 to 24 hours postoperatively. Platelet-derived microparticle levels were also increased preoperatively. At 6 hours postoperatively, the plasma level of platelet-derived microparticles was significantly increased. Plasma platelet-derived microparticle level was lower at 12 hours but only returned to the preoperative value at 7 days after grafting. There was a difference in the platelet-derived microparticle level at 7 days between patients with or without antiplatelet therapy (cilostazol). The effect of cytokines on platelet activation under high shear stress was also studied. Interleukin-6 and thrombopoietin enhanced both P-selectin expression and platelet-derived microparticle generation under high shear stress. These results suggest that platelet-derived microparticles are released by platelet activation after vascular grafting when certain cytokines increase under high shear stress and that antiplatelet therapy may reduce platelet-derived microparticle levels postoperatively.


Annals of Surgery | 1998

Preoperative assessment for laparoscopic cholecystectomy: feasibility of using spiral computed tomography.

A-Hon Kwon; Hiroyuki Inui; Atsushi Imamura; Shoji Uetsuji; Yasuo Kamiyama

OBJECTIVE The authors investigated the preoperative feasibility of using spiral computed tomography (SCT) after intravenous infusion cholangiography (IVC-SCT) for laparoscopic cholecystectomy. SUMMARY BACKGROUND DATA In laparoscopic cholecystectomy, the aberrant or unusual anatomy of the bile duct and severe inflammation or adhesions around the gallbladder sometimes require a conversion to open surgery. METHODS Laparoscopic cholecystectomies (LCs) were attempted on 440 patients, and preoperative IVC-SCT also was attempted in all of these patients. Using this spiral scanning technique, the bile ducts, cystic duct, and gallbladder were assessed for contour abnormalities, relative position, and filling defects. Forty-seven patients were diagnosed with having stones in their common bile duct or common hepatic duct. RESULTS Three-hundred eighty-seven patients out of the 440 patients (88.0%) who were subjected to IVC-SCT had the length and course of their cystic duct successfully determined. Anomalous unions of the cystic duct were seen in 59 (15.2%) of 387 patients with respect to the operative findings, and 48 of 440 patients (10.9%) had severe adhesions to Calots triangle and the surrounding tissues. In these 48 patients, 45 patients (94%) had a nonvisualized cystic duct on IVC-SCT. The preoperative assessment of the feasibility (dense adhesions obscuring Calots triangle) of using IVC-SCT demonstrated that the sensitivity, specificity, and accuracy were 93%, 98%, and 94%, respectively. Five patients had to be converted to open surgery, and the overall morbidity rates for patients undergoing laparoscopic cholecystectomy was 0.9% (4 of 440). CONCLUSIONS The most important factor in assessing the feasibility of using laparoscopic cholecystectomy is not the nonvisualized gallbladder, but the nonvisualized cystic duct on IVC-SCT. IVC-SCT may be of benefit to those patients scheduled to undergo laparoscopic cholecystectomy.


Journal of The American College of Surgeons | 2001

Laparoscopic cholecystectomy and choledocholithotomy in patients with a previous gastrectomy

A-Hon Kwon; Hiroyuki Inui; Atsushi Imamura; Masaki Kaibori; Yasuo Kamiyama

BACKGROUND An increased incidence of cholelithiasis has been widely reported after truncal vagotomy and after gastric resection. In the early phase of patient selection, previous gastrectomy has been considered a relative contraindication to laparoscopic cholecystectomy (LC). In this study, we examined the management of LC in patients with previous gastrectomy. STUDY DESIGN LC was attempted on 1,260 consecutive patients. Of these patients, 29 had a previous gastrectomy. Surgical procedures that had been performed included Billroth I gastrectomies (15), Billroth II gastrectomies (10), and total gastrectomies (4). There were 23 cases of cholelithiasis, 4 chronic cholecystitis, 2 gallbladder polyps, I porcelain gallbladder, and I gallbladder cancer. Nine patients were diagnosed with stones in their common bile duct or common hepatic duct. RESULTS Preoperatively, seven of nine patients with common bile duct stones were subjected to endoscopic sphincterotomy, and the stones were removed successfully from five of these patients. In the remaining two patients, common bile duct stones were removed by laparoscopic choledocholithotomy by choledochotomy. The LC was completed in 26 patients (90%) who had undergone previous gastrectomy. In 449 patients who had previous abdominal surgery without a gastrectomy, only 4 patients (0.9%) required open surgery. In contrast, three patients (10%) with previous gastrectomy required open surgery. No major complications were recorded in this study series, and no residual or retained stones were seen during a followup period of 3 months. CONCLUSIONS Clear visualization of anatomic structures and landmarks, and scrupulous hemostasis are needed to perform a safe LC in these patients. We conclude that in our study patients, a previous gastrectomy is considered an indication for LC and laparoscopic choledochotomy.


Surgery Today | 2001

Laparoscopic Splenectomy for a Lymphangioma of the Spleen: Report of a Case

A-Hon Kwon; Hiroyuki Inui; Katsushige Tsuji; Soichiro Takai; Atsushi Imamura; Yasuo Kamiyama

Abstract We present the first case report of a suc-cessful laparoscopic complete excision of a splenic lymphangioma. The splenic tumor was preoperatively diagnosed to be a lymphangioma by the combined modalities of ultrasonography, computed tomography, magnetic resonance imaging, and angiography. A laparoscopic splenectomy was subsequently performed and the pathological examination of the mass confirmed the diagnosis of a lymphangioma. Based on the above findings, a laparoscopic splenectomy is recommended when a splenic tumor is suspected to be either benign or borderline.


Surgery Today | 1996

Inflammatory pseudotumor of the liver: Report of a case and review of the literature

Shoji Uetsuji; Akihiko Nakagawa; A-Hon Kwon; Hisanao Komada; Atsushi Imamura; Yasuo Kamiyama

Only 56 cases of inflammatory pseudotumor of the liver have been reported in the world literature since its first documentation in 1953. We report herein the case of a 68-year-old man incidentally found to have a lesion in the right lobe of the liver which closely resembled a neoplasm on imaging studies. Thus, partial hepatic resection was performed and histological examination of the resected specimen revealed a diagnosis of inflammatory pseudotumor. Surgical resection is the preferred treatment for inflammatory pseudotumor of the liver, especially in patients for whom a definite histologic diagnosis cannot be made preoperatively or by intraoperative frozen sections. In fact, most of the patients reported in the literature recovered uneventfully after local resection without any postoperative complications, as did our patient.


American Journal of Surgery | 2003

Laparoscopic treatment using an argon beam coagulator for nonparasitic liver cysts

A.-Hon Kwon; Yoichi Matsui; Hiroyuki Inui; Atsushi Imamura; Yasuo Kamiyama

BACKGROUND Laparoscopic deroofing has been shown to produce good patient satisfaction and to have results similar to those of open surgical techniques. We evaluated the feasibility and efficacy of laparoscopic deroofing using an argon beam coagulator (ABC) in the patients with nonparasitic liver cysts. METHODS Laparoscopic deroofing for the treatment of liver cysts was attempted on 14 patients. After the deroofing, the secreting epithelium within the residual cystic cavity wall was destroyed using the ABC. RESULTS Laparoscopic deroofing was successful in all patients. No deaths or surgical morbidity occurred, and no postoperative complications were recorded. The median postoperative hospital stay was 7 days. The median follow-up was 56 months for all patients, and all patients have remained completely asymptomatic for 6 months after the surgery, with no recurrence of the cysts. CONCLUSIONS Our results indicate that laparoscopic deroofing using the ABC method in patients with nonparasitic liver cysts was effective in preventing cyst recurrence.


Surgery Today | 2001

Ruptured Dissecting Aneurysm in Bilateral Iliac Arteries Caused by Ehlers-Danlos Syndrome Type IV: Report of a Case

Atsushi Imamura; Hiroyuki Nakamoto; Tomohisa Inoue; Hitoshi Yamada; Masashi Okuno; Soichiro Takai; Hisanao Komada; A-Hon Kwon; Yasuo Kamiyama

Abstract Ehlers-Danlos syndrome (EDS) is an inherited disorder of connective tissue characterized by hyperextensible skin, hypermobile joints, and ab-normalities of the cardiovascular system. Ten types and several subtypes of EDS have so far been recognized based on genetic, clinical, and biochemical characteristics. The spectrum of the disorder varies from mild to life-threatening vascular complications. EDS type IV is a particularly dangerous form with a lethal spontaneous rupture of the major arteries and aneurysmal formation. We present herein a case of a ruptured dissecting aneurysm in the bilateral iliac arteries caused by EDS type IV. A previously healthy 33-year-old man without any physical features of this connective tissue disorder experienced a metachronous vascular rupture two times. Successful synthetic bypass grafting was performed with great difficulty. The diagnosis of EDS type IV was made afterwards based on an electrophoresis analysis of a skin biopsy specimen which revealed a lack of type III collagen. Surgical intervention in cases of arterial complications in EDS type IV patients have been reported to be both difficult and frequently unsuccessful. The early clinical recognition of this syndrome is therefore of great importance due to the hazards of such surgical therapies.


Surgery Today | 1997

Clinical evaluation of closed suction drainage following hepatectomy

Shoji Uetsuji; A-Hon Kwon; Hisanao Komada; Yoshinori Okuda; Atsushi Imamura; Yasuo Kamiyama

A prospective randomized study on 186 patients was conducted to determine the influence of closed suction drainage (n = 102) versus open drainage (n = 84) on the incidence of postoperative complications after elective hepatic resection. The patients were randomly allocated between the two groups. A total of 60 complications occurred in 31 of the 84 patients (36.9%) given open drainage, while 24 complications occurred in 15 of the 102 patients (14.7%) given closed suction drainage. The incidence of pleural effusion, postoperative ascites, and infected subphrenic collections was significantly lower in the closed suction drainage group than in the open drainage group, at 31%vs 16% (P < 0.05), 19%vs 3% (P < 0.01), and 17%vs 5% (P < 0.05) respectively. However, both groups showed similar rates of subphrenic hematoma and bile collection. These findings indicate that closed suction drainage significantly reduces the incidence of postoperative complications after elective hepatic resection.


Surgery Today | 1998

Seroma with fibrous capsule formation requiring a surgical resection after a modified radical mastectomy: report of a case.

Yoichi Matsui; Hidesuke Yanagida; Hideyuki Yoshida; Atsushi Imamura; Yasuo Kamiyama; Hiroshi Kodama

Seroma formation is the most common complication of a modified radical mastectomy for breast cancer. Although various management or risk factors for seroma formation have been previously reported, little has been published concerning seromas with fibrous capsule formation which ultimately require a surgical resection. We herein present a case who developed a seroma with a fibrous capsule after a modified radical mastectomy for breast cancer, in spite of an uneventful intraoperative and postoperative course. The seroma was refractory to all conventional treatments, and thus finally required a surgical resection.


Case reports in nephrology | 2014

Postoperative Atypical Hemolytic Uremic Syndrome Associated with Complement C3 Mutation

Eiji Matsukuma; Atsushi Imamura; Yusuke Iwata; Takamasa Takeuchi; Yoko Yoshida; Yoshihiro Fujimura; Xinping Fan; Toshiyuki Miyata; Takashi Kuwahara

Atypical hemolytic uremic syndrome (aHUS) can be distinguished from typical or Shiga-like toxin-induced HUS. The clinical outcome is unfavorable; up to 50% of affected patients progress to end-stage renal failure and 25% die during the acute phase. Multiple conditions have been associated with aHUS, including infections, drugs, autoimmune conditions, transplantation, pregnancy, and metabolic conditions. aHUS in the nontransplant postsurgical period, however, is rare. An 8-month-old boy underwent surgical repair of tetralogy of Fallot. Neurological disturbances, acute renal failure, thrombocytopenia, and microangiopathic hemolytic anemia developed 25 days later, and aHUS was diagnosed. Further evaluation revealed that his complement factor H (CFH) level was normal and that anti-FH antibodies were not detected in his plasma. Sequencing of his CFH, complement factor I, membrane cofactor protein, complement factor B, and thrombomodulin genes was normal. His ADAMTS-13 (a disintegrin-like and metalloprotease with thrombospondin-1 repeats 13) activity was also normal. However, he had a potentially causative mutation (R425C) in complement component C3. Restriction fragment length polymorphism analysis revealed that his father and aunt also had this mutation; however, they had no symptoms of aHUS. We herein report a case of aHUS that developed after cardiovascular surgery and was caused by a complement C3 mutation.

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Yasuo Kamiyama

Kansai Medical University

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A-Hon Kwon

Kansai Medical University

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Hisanao Komada

Kansai Medical University

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Masanori Kwon

Kansai Medical University

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Shoji Uetsuji

Kansai Medical University

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Soichiro Takai

Kansai Medical University

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Hiroyuki Inui

Kansai Medical University

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Masashi Okuno

Kansai Medical University

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Shouji Uetsuji

Kansai Medical University

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