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Dive into the research topics where Masanori Yokoyama is active.

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Featured researches published by Masanori Yokoyama.


Journal of Gastroenterology and Hepatology | 1995

Effects of nifedipine on hepatic venous pressure gradient and portal vein blood flow in patients with cirrhosis

Kazuhiro Ota; Hiroshi Shijo; Hiroshi Kokawa; Katsuhiko Kubara; Tetsuhiro Kim; Nobuo Akiyoshi; Masanori Yokoyama; Makoto Okumura

Abstract We investigated the effects of nifedipine on splanchnic haemodynamics in 13 patients with cirrhosis and portal hypertension, and in 10 control subjects using hepatic venous catheterization and pulsed Doppler ultrasound. There were no significant changes in systemic or splanchnic haemodynamics in control patients. In contrast, systemic vascodilatation, evidenced by significant decreases in mean arterial pressure and systemic vascular resistance, was observed in patients 20 min after sublingual application of 10 mg nifedipine. Moreover, hepatic venous pressure gradient and portal vein blood flow significantly increased after nifedipine administration. There was a significant correlation between the percentage increases in portal vein blood flow and in hepatic venous pressure gradient. However, no correlation was found between the percentage change in cardiac output and that in portal vein blood flow. Thus the increase in portal vein blood flow appears to be related to splanchnic arterial vasodilatation by nifedipine. Consequently, nifedipine has deleterious effects on portal haemodynamics in patients with cirrhosis. As nifedipine may potentially increase the risk of variceal haemorrhage in patients with less advanced varices, this drug should be used with caution in patients with chronic liver disease.


Hepatology Research | 2000

The natural history and prognostic factors in patients with cirrhosis and gastric fundal varices without prior bleeding.

Nobuo Akiyoshi; Hiroshi Shijo; Takeshi Iida; Masanori Yokoyama; Tetsuhiro Kim; Kazuhiro Ota; Kazuo Tamura

Objectives and methods: The prognostic factors have not yet been fully evaluated in patients with cirrhosis and gastric fundal varices (FV). We investigated the natural history of 145 patients with cirrhosis and FV with no history of bleeding. Various possible prognostic factors, which include clinical, biochemical, and endoscopical variables, were analyzed using Coxs proportional hazard model. Results: Among the 145 patients with cirrhosis and FV, there were 76 patients in class A, 45 in class B and 24 class C according to Childs classification. Sixty-five patients had concomitant hepatocellular carcinoma at the time of enrollment. Seventy deaths and 34 episodes of the hemorrhage from FV occurred during the mean follow-up period of 26.4 months. The cumulative survival rates at 1, 3, and 5 years were 75, 53 and 34%, respectively. The cause of death was related to gastrointestinal hemorrhage in 18 patients (15 deaths were related to FV hemorrhage), hepatic failure in 22, hepatocellular carcinoma in 22, and other causes in eight patients. In patients with small-, medium-, and large-sized FV, the deaths related to FV hemorrhage were 4, 21 and 54%, respectively. Overall, the death related to FV hemorrhage was 21%. A multiple regression analysis using Coxs model showed hemorrhage from FV, the presence of hepatocellular carcinoma and poor Childs status were all highly significant prognostic factors. Conclusion: The natural history of the patients with cirrhosis and FV was adversely modified by the hemorrhage from FV, concomitant hepatocellular carcinoma and poor hepatic functional reserve. Since the number of deaths related to FV hemorrhage was great in patients with large-sized FV, it is important to identify high-risk large FV and its prophylactic obliteration. Further studies are needed to elucidate the efficacy of prophylactic obliteration of large-sized FV.


Hepatology International | 2008

Spontaneous rupture of metastatic α-fetoprotein-producing gastric cancer of the liver

Tetsuro Sohda; Takayuki Hanano; Hisanori Miyamoto; Yoko Kitano; Kaoru Iwata; Masanori Yokoyama; Makoto Irie; Yasuaki Takeyama; Satoshi Shakado; Shotaro Sakisaka

An 80-year-old man was admitted to our hospital because of the rupture of the liver. Laboratory data showed iron-deficiency anemia, although there was no liver dysfunction. A computed tomography scan showed large liver tumor with intraperitoneal hemorrhage, and since a serum level of α-fetoprotein (AFP) was extremely high, we initially suspected a rupture of hepatocellular carcinoma (HCC). Transarterial embolization was performed to stop bleeding from the tumor, followed by an endoscopic examination that revealed advanced gastric cancer. Histological analysis revealed that both the gastric and the hepatic tumors were moderately to poorly differentiated adenocarcinoma, as well as that both tumors were immunohistochemically positive for AFP. Finally, we diagnosed AFP-producing gastric cancer associated with liver metastasis. Rupture of metastatic liver cancer is rare, and accordingly, distinction from HCC is important, particularly for the cases of AFP-producing gastric cancer.


Journal of Gastroenterology and Hepatology | 1996

Effects of endoscopic variceal sclerotherapy on azygos vein blood flow and systemic haemodynamics

Masanori Yokoyama; Hiroshi Shijo; Kazuhiro Ota; Katsuhiko Kubara; Hiroshi Kokawa; Tetsuhiro Kim; Nobuo Akiyoshi; Hideo Tokumitsu; Makoto Okumura

The present study was designed to determine the systemic haemodynamic effects of obliterating oesophageal varices by endoscopic sclerotherapy. We evaluated systemic and splanchnic haemodynamics before and after the first course of sclerotherapy in cirrhotic patients. The baseline cardiac index was significantly correlated with baseline azygos vein blood flow (r = 0.64; P< 0.01) and the azygos vein blood flow and cardiac index significantly decreased (‐33% and ‐16%, respectively; P< 0.01) following sclerotherapy. The systemic vascular resistance index was also increased significantly (+20%; P<0.01) in these patients. Moreover, the per cent change in azygos vein blood flow was directly correlated with that of the cardiac index (r=0.51; P< 0.03). We conclude from these findings that the obliteration of portosystemic collaterals by sclerotherapy significantly reverses hyperdynamic circulation in such patients via a decrease in cardiac preload. The blood flow of the portosystemic shunt per se is a leading contributor to the hyperdynamic circulation observed in patients with well‐developed portal systemic collateral vessels.


The American Journal of Gastroenterology | 1998

Effects of endoscopic variceal ligation on oxygen transport and the arterial lactate levels in patients with cirrhosis

Takeshi Iida; Hiroshi Shijo; Masanori Yokoyama; Kazuhiro Ota; Shigeru Kakumitsu; Tetsuhiro Kim; Nobuo Akiyoshi; Makoto Okumura

Abstract Objective: Despite the increased cardiac output and oxygen delivery, an impaired oxygen uptake has been noted in patients with cirrhosis. We recently observed that endoscopic variceal ligation decreased the cardiac output due to a reduction in the cardiac preload. It is thus possible that a variceal ligation decreases the oxygen delivery and thereby negatively influences tissue oxygenation in patients receiving such treatment. We thus investigated the effects of variceal ligation on oxygen delivery, oxygen uptake, and the arterial lactate levels. Methods: There were 22 patients with compensated cirrhosis and risky esophageal varices (Child’s class A:B = 13:9). Twelve patients underwent an endoscopic variceal ligation and 10 patients received gastroscopy as a control. The cardiac function, blood gas status, oxygen delivery, and arterial lactate concentration were also assessed before and after variceal ligation. The oxygen uptake was calculated by the Fick equation. Results: Following variceal ligation, there was an immediate decrease in the cardiac output and oxygen delivery. The reduction in oxygen delivery was associated with a slight but significant increase in the arterial lactate concentration. The decreased oxygen delivery was also associated with a concomitant decrease in the oxygen uptake. In the control subjects, gastroscopy did not alter the systemic hemodynamics, arterial oxygen status, or arterial lactate levels. Conclusion: We found a significant decrease in the oxygen delivery in patients undergoing an endoscopic variceal ligation. Such deteriorated tissue oxygenation may be serious especially in patients with a low oxygen transport ability such as in patients with variceal hemorrhage with anemia. However, the clinical significance of these changes remains unclear and further studies are therefore warranted.


Gastroenterology | 1995

Systemic hemodynamics and serum nitrate levels in patients undergoing endoscopic variceal ligation

Masanori Yokoyama; Hiroshi Shijo; K. Ota; K Kubara; H Kokawa; Makoto Okumura

The effects of endoscopic variceal ligation (EVL) on systemic hemodynamics are unknown. This study was conducted to determine whether the obliteration of portal-systemic collaterals by EVL affects systemic hemodynamics and serum nitrate concentrations in patients with compensated cirrhosis. We measured systemic and hepatic hemodynamics, azygos vein blood flow (AzBF), and serum nitrate concentrations before and immediately following EVL. A prompt decrease in left ventricular end-diastolic volume (LVEDV), stroke volume, cardiac index (CI), and an increase in systemic vascular resistance index (SVRI) were observed following variceal ligation. The reduction in LVEDV was associated with a decline in CI with a rise in SVRI. There was also a prompt reduction in serum nitrate concentration following variceal ligation. AzBF also significantly decreased following variceal ligation. These findings indicate that EVL decreased cardiac output via a reduction in cardiac preload (central venous return). Blood flow through portal-systemic collaterals has an important role in the enhanced cardiac preload of cirrhotic patients. The sudden decrease in serum nitrate concentrations suggests that endogenous nitric oxide may be involved in the regulation of systemic hemodynamics in patients with compensated cirrhosis.


Advances in Hepatology | 2015

The Incidence of Hepatocellular Carcinoma after Balloon-Occluded Retrograde Transvenous Obliteration

Keiji Yokoyama; Makoto Irie; Akira Anan; Masanori Yokoyama; Naoaki Tsuchiya; Atsushi Fukunaga; Kazuhide Takata; Takashi Tanaka; Genryu Hirano; Daisuke Morihara; Yasuaki Takeyama; Satoshi Shakado; Tetsuro Sohda; Shotaro Sakisaka

Balloon-occluded retrograde transvenous obliteration (BRTO) is a highly effective therapy for gastric varices with liver cirrhosis. We have investigated the incidence of hepatocellular carcinoma (HCC) after BRTO. We enrolled 71 patients with viral hepatitis in which HCC had not appeared with liver imaging findings at the time of BRTO. The overall survival rate after BRTO was 86.8%, 76.1%, and 50.5% at 1, 3, and 5 years. The occurrence rate of HCC after BRTO was 20.9%, 41.1%, and 60.7% at 1, 3, and 5 years, especially showing a higher occurrence of HCC at one year. Meanwhile, the occurrence rate of HCC after treatment which excluded BRTO for esophagogastric varices in patients was 6.3%, 19.2%, and 42.5% at 1, 3, and 5 years. The log-rank test revealed that the occurrence rate of HCC after treatment was significantly higher in the BRTO group compared with that in the non-BRTO group (). The recurrence rate of HCC after BRTO was 35.8% and 80.0% at 1 and 3 years. The present study demonstrated a high incidence of HCC after BRTO in liver cirrhosis patients with viral hepatitis infection. We have suggested the potential for BRTO to accelerate hepatocarcinogenesis.


Journal of International Medical Research | 2009

Characteristic Genotypes of Vascular Endothelial Growth Factor are Susceptible to Ascites in Patients with Cirrhosis

Tetsuro Sohda; Kaoru Iwata; Makoto Irie; Yasuaki Takeyama; Hidetoshi Nakane; Daisuke Morihara; Yuji Kitamura; Masanori Yokoyama; Satoshi Shakado; Hiroshi Watanabe; Shotaro Sakisaka

This study was designed to investigate whether different vascular endothelial growth factor (VEGF) genotypes are associated with ascites formation in cirrhotic patients. Seventy cirrhotic patients were included in the study: 25 cirrhotic patients with ascites and 45 cirrhotic patients without ascites. Patient characteristics were investigated and compared between the two groups. With regard to VEGF genotype, 42 patients were C/C and 28 patients were T/T or C/T. The genotypes T/T or C/T were observed in 23 cases (51%) among the non-ascites group, but in only five cases (20%) among the ascites group. Serum levels of albumin and creatinine, and the VEGF genotypes were significantly different between the two groups. Multiple regression analysis showed that serum levels of creatinine and the VEGF genotypes were significantly correlated with ascites formation. Thus, it can be concluded that VEGF genotyping might be a valuable susceptibility marker for ascites formation in cirrhotic patients.


Hepatology | 1998

Effects of l‐arginine on the systemic, mesenteric, and Hepatic circulation in patients with cirrhosis

Shigeru Kakumitsu; Hiroshi Shijo; Masanori Yokoyama; Tetsuhiro Kim; Nobuo Akiyoshi; Kazuhiro Ota; Katsuhiko Kubara; Makoto Okumura; Kazuhide Inoue


Gastrointestinal Endoscopy | 2006

Colonic varices treated by balloon-occluded retrograde transvenous obliteration in a cirrhotic patient with encephalopathy: a case report

Akira Anan; Makoto Irie; Hiroshi Watanabe; Tetsuro Sohda; Kaoru Iwata; Norihisa Suzuki; Makoto Yoshikane; Hidetoshi Nakane; Tomoko Hashiba; Masanori Yokoyama; Hideyuki Higashihara; Masatoshi Okazaki; Shotaro Sakisaka

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