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Dive into the research topics where Shinichi Mezawa is active.

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Featured researches published by Shinichi Mezawa.


The American Journal of Gastroenterology | 2001

Effect of transjugular intrahepatic portosystemic shunt formation on portal hypertensive gastropathy and gastric circulation

Shinichi Mezawa; Hisato Homma; Hidetoshi Ohta; Eiichi Masuko; Tadashi Doi; Koji Miyanishi; Koichi Takada; Takehiro Kukitsu; Tsutomu Sato; Yoshiro Niitsu

OBJECTIVES:The aim of this study was to investigate the effect of a transjugular intrahepatic portosystemic shunt (TIPS) on portal hypertensive gastropathy (PHG) and gastric hemodynamics.METHODS:A total of 16 patients with cirrhosis and portal hypertensive gastropathy were prospectively studied. Of these, 12 patients underwent TIPS for esophageal varices and four for refractory ascites. Gastric mucosal blood flow (GMBF) was assessed by laser Doppler flowmeter, and total blood flow (TBF) in submucosa and mucosa by near-infrared endoscopy. Portal venous pressure was obtained by a transducer during the TIPS procedure. The severity of portal hypertensive gastropathy was classified as none, mild, or severe. The examinations were performed before and 2 wk after the procedure.RESULTS:TIPS significantly reduced portal venous pressure. PHG improved in all four patients with severe PHG and in five of 12 patients with mild PHG after treatment. Gastric mucosal blood flow increased from 49.0 to 55.6 ml/min/100 g after TIPS. In contrast, TBF decreased from 0.35/s to 0.27/s after treatment. Liver function tests showed no significant changes before and after the procedure.CONCLUSIONS:It is considered that TIPS may have a beneficial effect on PHG at least for a short time. The mechanism by which PHG improves may be closely related to the improvement of the injured gastric perfusion in cirrhotic patients with PHG.


Hepatology Research | 2002

Mechanisms for increment of platelet associated IgG and platelet surface IgG and their implications in immune thrombocytopenia associated with chronic viral liver disease

Tadashi Doi; Hisato Homma; Shinichi Mezawa; Junji Kato; Katsuhisa Kogawa; Sumio Sakamaki; Yoshiro Niitsu

In addition to hypersplenism, immunological destruction of platelets by elevated platelet associated IgG (PAIgG) and platelet surface IgG (PSIgG) has been proposed as a causative factor for thrombocytopenia in chronic liver disease (CLD), although the implication of PAIgG may be debatable since recent investigations on idiopathic thrombocytopenic purpura disclosed the fact that PAIgG largely relates to the intra-platelet IgG in alpha-granules and not to PSIgG. Further, with regard to the elevated PSIgG of CLD, characterization as to whether it mainly represents anti-platelet glycoprotein (GP) antibodies or IgG contained in the immune complex has not been elucidated. Thirty-seven patients with chronic viral liver disease (CVLD); 31 hepatitis C and 6 hepatitis B were included in this study. First we monitored the changes in levels of PAIgG, alpha-granule IgG, PSIgG and mean platelet volume (MPV) during the course of partial splenic arterial embolization (PSE). The elevated level of PAIgG decreased after PSE, paralleling that of alpha-granule IgG, while PSIgG showed no change; MPV decreased reciprocally with the increase of platelet count. These results indicate that the increment of PAIgG in CVLD may be caused by accelerated destruction of platelets; this generally evokes hyperproduction of large-sized thrombocytes, which have an increased capability to uptake circulating IgG. To characterize PSIgG, we then tested CVLD patients for antiplatelet GP antibodies and found only a 5.4% positivity. It was also found that circulating immune complex levels in CVLD patients were clearly elevated, correlating with the levels of PSIgG. Thus, it was surmised that immune complexes bound to the platelet surface, and not platelet specific GP antibodies, may be playing a crucial role in platelet destruction of CVLD, possibly through phagocytosis by macrophages.


Journal of Vascular and Interventional Radiology | 2004

Selective Embolization of the Splenic Vein in Patients with Hepatic Encephalopathy and Splenorenal Shunt

Shinichi Mezawa; Hisato Homma; Takehide Akiyama; Shinichi Katsuki; Ken Murakami; Kenichiro Hirata; Katsuhisa Kogawa; Syo Takahashi; Tsutomu Sato; Tadashi Doi; Yoshiro Niitsu

Obliteration of portal-systemic shunts is effective for portosystemic encephalopathy but is often associated with complications such as retention of ascites and worsening of esophageal varices. Selective embolization of the splenic vein was performed on six patients with hepatic encephalopathy and splenorenal shunts. Hepatic encephalopathy was not observed in four patients after the procedure. Neither retention of ascites nor rupture of esophageal varices was observed because postoperative elevation of portal venous pressure was not as great as that seen when shunt obliteration is performed. This procedure can be an effective and safe treatment option for hepatic encephalopathy with a splenorenal shunt.


Journal of Gastroenterology | 1996

Bacterial adhesion on hydrophilic heparinized catheters, with compared with adhesion on silicone catheters, in patients with malignant obstructive jaundice

Hisato Homma; Shoji Nagaoka; Shinichi Mezawa; Tomohiko Matsuyama; Eiichi Masuko; Noriyoshi Ban; Naoki Watanabe; Yoshiro Niitsu

To study the inhibitory effects on bacterial adhesion of a newly devised, hydrophilic heparinized catheter to be used in patients with malignant obstructive jaundice, a randomized controlled study of indwelling endoprostheses was performed, using implantable port-connected heparinized catheters (n=25) and silicone catheters (n=21). Catheters with-drawn from patients were cultured for bacteria and examined by electron microscopy for the presence of adherent organisms. In vitro examination of the two type of catheters exposed to suspensions ofEschericia coli andStaphylococcus aureus was performed using electron microscopy and a luminometer. The formation of a biofilm coated with glycocalyces was found in silicone catheters, but not in the heparinized catheters. In vitro experiments demonstrated little bacterial adhesion to the heparinized surface, but significant formation of biofilm on the silicone surface. Anionically charged heparinized catheters have inhibitory effects on bacterial adhesion, and the surface charge of the catheter may be a factor in inhibiting this adhesion.


International Journal of Clinical Oncology | 2004

Advanced pancreatic carcinoma showing a complete response to arterial infusion chemotherapy

Hisato Homma; Takehide Akiyama; Shinichi Mezawa; Tadashi Doi; Kunihiro Takanashi; Takuro Machida; Ken Murakami; Shinichi Katsuki; Tsutomu Sato; Kenichiro Hirata

We report a patient with advanced carcinoma of the pancreatic body and tail with multiple liver metastases who showed a complete response to hepatic and splenic arterial infusion chemotherapy (HSAIC) with gemcitabine and 5-fluorouracil, following transcatheter peripancreatic arterial embolization (TPPAE) and partial splenic embolization (PSE). Nonresectable advanced pancreatic carcinoma tends to have a low response to medical treatment, with the median survival time being 6 months or less for stage IV cases. We disclose herein that the median survival time of patients receiving HSAIC after TPPAE is more than three times longer than the survival time attained with conventional treatments. However, in patients with advanced carcinoma of the pancreatic tail, for which TTPAE is not applicable, survival times remain low. Thus, in the patient described here, we also performed embolization of the left gastric and short gastric arteries as well as PSE to increase the flow within the great pancreatic and caudal pancreatic arteries via the splenic artery, and gemcitabine and 5-fluorouracil were administered via the splenic artery. As a result of these procedures, marked reduction in the advanced carcinoma of the pancreatic body and tail and of liver metastases was attained.


European Journal of Gastroenterology & Hepatology | 2001

A case of successful management of portosystemic shunt with autosomal dominant polycystic kidney disease by balloon-occluded retrograde transvenous obliteration and partial splenic embolization.

Kohichi Takada; Hisato Homma; Minoru Takahashi; Shinichi Mezawa; Koji Miyanishi; Tetsuya Sumiyoshi; Tadashi Doi; Takehiro Kukitsu; Junji Kato; Yoshiro Niitsu

We describe a patient with autosomal dominant polycystic kidney disease who was successfully managed for severe abdominal distension, impaired liver function and a portosystemic shunt by interventional therapies. The patients intra-hepatic portal vein was compressed and narrowed by multiple liver cysts, which resulted in a decrease of the portal blood flow and portal hypertension due to a huge gastro-renal shunt These haemodynamic changes were assumed to contribute to insufficient protein synthesis in the liver. Therefore, we first repeatedly performed minocycline hydrochloride instillations to treat the multiple liver cysts. Then, we conducted a partial splenic embolization to prevent elevation of the portal vein pressure prior to balloon-occluded retrograde transvenous obliteration which was performed to increase the portal blood flow. The portal blood flow markedly increased, and protein synthesis in the liver also recovered and the clinical symptoms improved. The patient has been monitored for more than two years up to the present and her liver function parameters have remained within the normal range. Renal insufficiency is known to be a major prognostic factor in autosomal dominant polycystic kidney disease. In some cases, however, liver involvement with multiple cysts may result in a fatal outcome. In such cases, interventional therapies, as provided to this patient, should be considered.


CardioVascular and Interventional Radiology | 2001

Re: Spontaneous rupture of renal metastasis of hepatocellular carcinoma: management by emergency transcatheter arterial embolization.

Shinichi Mezawa; Hisato Homma; Tadashi Doi; Koichi Takada; Takehiro Kukitsu; Miyuki Kinebuchi; Akihiro Matsuura; Noriyuki Sato; Fumie Mezawa; Koji Miyanishi; Yoshiro Niitsu

Spontaneous rupture of a primary lesion in hepatocellular carcinoma (HCC) is not unusual, and may be one of the defining factors in the prognosis [1]. However, rupture of an HCC metastatic lesion is very rare [2–4]. There are no reports in the literature describing cases with ruptured renal HCC metastasis. We report a case of massive retroperitoneal hemorrhage from the site of a right renal HCC metastasis. The bleeding was successfully controlled by transcatheter arterial embolization (TAE). In August 1997 a 67-year-old man with liver cirrhosis associated with hepatitis C virus had undergone TAE for an HCC in S1 measuring 3.5 3.8 cm. Following the first treatment, repeat TAE therapy was performed three times for recurrent HCC in S1. In December 1998, a chest X-ray showed lung metastasis in the right middle lobe, for which 48 Gy radiotherapy was performed. In January 1999, he was readmitted to our hospital with a chief complaint of severe headache. Brain computed tomography (CT) revealed a tumor in the left occipital lobe, suggesting HCC metastasis. He underwent surgery on the 4th hospital day. Histological examination of the tumor showed poorly differentiated HCC. He had no headache after the operation and was then discharged on the 15th hospital day. In March 1999, CT scan revealed new lesions in the bilateral kidney (Fig. 1A) and the left lung, suggesting HCC metastases. We decided that further treatment would be futile, so we followed him conservatively. On April 16, 1999, he was brought to our hospital by ambulance, presenting with right flank pain and hypovolemic shock. Abdominal CT scan showed a retroperitoneal hematoma in contact with the right kidney which was displaced ventrally (Fig. 1B). Enhancement with contrast material was seen in the hematoma, suggesting persistent bleeding. Three hours after the admission, emergency angiography was performed. A selective right renal arteriogram showed tortuous arteries and a 2-cm tumor at the lower pole of the right kidney (Fig. 2A), where extravasation of contrast material was observed. This suggested a tumor rupture causing continued bleeding. In order to achieve hemostasis, TAE was performed using Gelform and coils. A right renal arteriogram after TAE showed occlusion of the feeding artery to the tumor and preservation of normal renal parenchyma (Fig. 2B). Subsequently, his blood pressure stabilized and his general condition improved. Three months after TAE the patient died from recurrence of brain metastasis. Tumor rupture, however, never recurred. At autopsy we discovered HCC in the liver, bilateral lung, right parietal pleura, brain, spleen, and left kidney. The liver showed macronodular cirrhosis and a 3-cm diameter lesion of poorly differentiated HCC, exposed to the inferior vena cava, in S1 with necrotic tissue due to treatment. The tumor of the right kidney was thoroughly necrotic. All tumor cells found at autopsy had the same histological appearance as the primary tumor. Renal metastasis of HCC is often observed at autopsy, but it is rarely clinically diagnosed. Nakashima et al. [5] reported that extrahepatic metastasis was found in 144 (64%) of 225 autopsies in patients with HCC and renal metastasis in five (2.2%). Systemic metastasis was observed in our patient, probably because the HCC was exposed to the inferior vena cava and consisted of poorly differentiated cells, although primary HCC was localized in S1. Spontaneous rupture of primary HCC into the peritoneal cavity is reported to occur in 10% of cases [1]. In contrast, spontaneous rupture of metastatic lesions is very rare but has been previously reported in the lung, rib, spleen, pleura, and peritoneum [2–4]. All of these reported cases were treated conservatively and the patient died of hemorrhagic shock or hepatic failure. It is thought that massive hemorrhage may become one of the causes of hepatic failure in cirrhotic patients with ruptured HCC, who often have limited hepatic reserve for ischemia. An early diagnosis of the rupture site is required. In our case, dynamic CT scan showed the presence of the hematoma and active bleeding and was useful for an early diagnosis. Control of bleeding from a ruptured HCC is often difficult. Recently, several reports have described the usefulness of TAE, tolerable for patients with severe liver dysfunction in contrast to surgery, for the management of spontaneous rupture of primary HCC [6]. TAE is effective in achieving immediate hemostasis in almost all patients. Its immediate mortality rate is far less than that of surgery. As to the kidney, there have been many reports on the effectiveness of TAE for rupture of renal angiomyolipoma [7]. TAE is a minimally invasive therapy and can preserve the normal renal parenchyma by selective embolization of the feeding artery to the tumor. In conclusion, selective arterial embolization is an effective and safe procedure to manage tumor rupture. It is thought that TAE may be appropriate therapy even for ruptured renal HCC metastasis.


Hepatology | 2000

A Study of Carboplatin-Coated Tube for the Unresectable Cholangiocarcinoma

Shinichi Mezawa; Hisato Homma; Tsutomu Sato; Tadashi Doi; Koji Miyanishi; Koichi Takada; Takehiro Kukitsu; Kazuyuki Murase; Naoto Yoshizaki; Minoru Takahashi; Sumio Sakamaki; Yoshiro Niitsu


Hepato-gastroenterology | 2003

Superselective transcatheter embolization for acute lower gastrointestinal hemorrhage after endoscopic mucosal resection: a report of 3 cases.

Shinichi Mezawa; Hisato Homma; Kazuyuki Murase; Tadashi Doi; Satoshi Iyama; Kohichi Takada; Kenichiro Hirata; Fumie Mezawa; Yoshiro Niitsu


Hepato-gastroenterology | 2004

A comparative randomized trial of intermittent intrahepatic arterial carboplatin- versus doxorubicin-lipiodol emulsion in advanced hepatocellular carcinoma (stage IV).

Hisato Homma; Shinichi Mezawa; Tadashi Doi; Koji Miyanishi; Kohichi Takada; Takehiro Kukitsu; Takaomi Oku; Eiichi Masuko; Shuuichi Nojiri; Yoshiro Niitsu

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Yoshiro Niitsu

Sapporo Medical University

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Hisato Homma

Albert Einstein College of Medicine

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Tadashi Doi

Memorial Hospital of South Bend

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Koji Miyanishi

Sapporo Medical University

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Takehiro Kukitsu

Sapporo Medical University

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Tsutomu Sato

Sapporo Medical University

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Eiichi Masuko

Sapporo Medical University

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Kenichiro Hirata

Sapporo Medical University

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Kohichi Takada

Sapporo Medical University

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Koichi Takada

Sapporo Medical University

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