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Biomedical subjects

Shohei Yamaguchi

Publications and source records attributed to Shohei Yamaguchi.

7 recordsLinked to original sources
PubMed2003

A robotic surgery system (da Vinci) with image guided function--system architecture and cholecystectomy application.

We have developed a data fusion system for the robotics surgery system "da Vinci". The data fusion system is composed of an optical 3D location sensor and a digital video processing system. The 3D location sensor is attached to the da Vinci's laparoscope and measures its location and direction. The digital video processing system captures the laparoscope's view and superimposes 3D patient's organ models onto the captured view in real-time. We applied the system to "da Vinci" and examined this system during a cholecystectomy. In this experiment, the surgeon was able to observe the inner conditions of the organs with a stereo view.

Cholecystectomy↗
PubMed2002

Pathogenesis of portal hypertensive gastropathy: a clinical and experimental review.

Portal hypertensive gastropathy (PHG) is recognized as a clinical entity in portal hypertension, but the pathogenesis of PHG is still unclear. Therefore, we reviewed the current state of knowledge concerning the portal hypertensive gastric mucosa and hypothesized the pathogenesis of PHG. Elevated portal pressure can induce changes of local hemodynamics, thus causing congestion in the upper stomach and gastric tissue damage. These changes may then activate cytokines and growth factors, such as tumor necrosis factor alpha, which are substances that activate endothelial constitutive nitric oxide synthase and endothelin 1 in the portal hypertensive gastric mucosa. Overexpressed nitric oxide synthase produces an excess of nitric oxide, which induces hyperdynamic circulation and peroxynitrite overproduction. The overproduction of peroxynitrite, together with endothelin overproduction may cause an increased susceptibility of gastric mucosa to damage. When combined with the characteristics of impaired mucosal defense and healing, these factors may together produce PHG in patients with portal hypertension.

Animals↗
PubMed2002

A new era of robotic surgery assisted by a computer-enhanced surgical system.

Computer-enhanced robotic surgery has now been introduced into general surgical practice. The robotic system enables us to manipulate endoscopic instruments, as well as instruments during open surgical intervention, regarding both the operative field and operation techniques. This technologic innovation should therefore help surgeons overcome various difficulties and allow them to perform more precise, safer, and more minimally invasive surgery in the coming era.

General Surgery↗
PubMedDate not supplied

Laparoscopic splenectomy for portal hypertension.

BACKGROUND/AIMS: Laparoscopic splenectomy is now increasingly being performed. However, controversy remains regarding the effectiveness of a laparoscopic splenectomy for patients with portal hypertension. METHODOLOGY: Seventy-three patients with portal hypertension who underwent a laparoscopic splenectomy from February 1992 until October 2000 were reviewed and the effectiveness of the procedures for portal hypertension was evaluated. Forty-two patients had esophagogastric varices and twenty had a concomitant hepatocellular carcinoma. The indications for surgery were bleeding tendency due to thrombocytopenia (n = 40), difficulty in receiving treatment for hepatocellular carcinoma due to thrombocytopenia (n = 18), and sclerotherapy-resistant esophagogastric varices (n = 15). RESULTS: A laparoscopic splenectomy was successfully performed in all the patients. The rate of conversion to conventional open surgery was 9.6% (7/73). The mean operative time was 210.1 +/- 101.9 minutes, and the estimated blood loss was 374.7 +/- 352.4 mL. There were no cases of mortality, and morbidity was encountered in 11.0% of patients. The increase in the platelet count correlated significantly to the spleen weight (P < 0.001). The platelet count had been maintained at over 10 x 10(4)/mm3 for over three years. Eighteen patients with hepatocellular carcinoma successfully underwent treatment for hepatocellular carcinoma after surgery and no recurrence of esophagogastric varices was encountered. CONCLUSIONS: A laparoscopic splenectomy resulted in the successful secondary treatment of hepatocellular carcinoma and esophagogastric varices. Portal hypertension was not a contraindication. A laparoscopic approach is therefore the procedure of choice for a splenectomy in portal hypertension.

Aged↗