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Koichi Suto

Publications and source records attributed to Koichi Suto.

12 recordsLinked to original sources
PubMed2005

Kinetics of trichloroethene dechlorination with iron powder.

The dechlorination of trichloroethene (TCE) with metallic iron is an advantageous method for the remediation of contaminated groundwater and soil. The toxic reaction intermediates such as dichloroethenes (DCEs) and vinyl chloride (VC), however, occasionally accumulate in the pathway of the reaction. We have been trying to suppress these intermediates by using metallic iron powder containing impurities. In order to investigate the reaction pathways, we measured the production rates of the intermediates and the final products of the dechlorination of TCE such as DCEs, VC, ethyne or ethene. Ethyne, ethene, ethane and cis-DCE were observed as the major products, and trans-DCE, 1,1-DCE, VC, C3-hydrocarbons (such as propane, propylene), C4-hydrocarbons (such as n-butane) and methane were observed as the minors. Also the rate constants of TCE to ethyne and ethyne to ethene were larger than any other constants. These fact show the production of ethene/ethane via ethyne is the main pathway of the dechlorination of TCE using the metallic iron powder.

Alkynes↗
PubMed2003

Inhibitory effect of high concentrations of ferric ions on the activity of Acidithiobacillus ferrooxidans.

The influence of high concentrations of ferric ions on the biochemical activity of Acidithiobacillus ferrooxidans was studied using intact cells. The specific oxidation rate of ferrous ions decreased with increasing ferric ion concentration. Lineweaver-Burk plots revealed typical competitive inhibition kinetics, because the slopes varied with the ferric ion concentration. A linear relationship between the slope and the square of the ferric ion concentration revealed that the iron-oxidizing enzyme system of A. ferrooxidans was competitively inhibited by about two molecules of ferric ion. The kinetic equation based on this inhibition model agreed with the experimental observation at a high ferric ion concentration where the bacterium is usually exposed in bioleaching and biooxidation plants.

Journal Article↗
PubMed2003

Evaluation of preoperative portal embolization for safe hepatectomy, with special reference to assessment of nonembolized lobe function with 99mTc-GSA SPECT scintigraphy.

BACKGROUND: Preoperative portal embolization (PE) is used to stimulate liver hypertrophy in the nonembolized lobe. We studied liver volume and function with computed tomography and technetium-99m-galactosyl human serum albumin ((99m)Tc-GSA) scintigraphy before PE and at 1 or 2 weeks after PE. METHODS: Right PE was performed in 30 patients. Morphologic and functional hypertrophy in the left lobe after PE was determined and related to the presence or absence of cholestasis, biliary drainage of the embolized lobe, and postoperative liver failure. RESULTS: The volume of the left lobe and (99m)Tc-GSA uptake increased rapidly for the first week after PE, but no significant increase was seen during the second week. Morphologic hypertrophy was less pronounced in patients with jaundice (P =.03). When PE was performed at a total bilirubin level above 2 mg/dL, the interval between PE and surgery was prolonged because of cholangitis and liver abscess formation. The net morphologic hypertrophy ratio was significantly higher in livers that had undergone left lobe drainage only (9.1% +/- 0.9%) compared with those in which there was drainage of the embolized lobes (5.7% +/- 0.9%; P =.03). The volume and (99m)Tc-GSA uptake of the left lobe in the second week after PE was significantly smaller in patients with postoperative liver failure (33.7% +/- 2.4% and 18.0% +/- 2.1%, respectively) than in patients without liver failure (46.2% +/- 1.4% and 38.4% +/- 2.3%; P =.003 and P =.01, respectively). CONCLUSION: In the nonembolized lobe, the functional increase in (99m)Tc-GSA uptake is more pronounced than suggested by the degree of morphologic hypertrophy. Whenever possible, biliary drainage should not be performed in the lobe undergoing hepatectomy. (99m)Tc-GSA SPECT scintigraphy is useful for the evaluation of postoperative liver failure.

Animals↗
PubMed2002

Significance of altered bilirubin subfractions in bile following hepatectomy.

BACKGROUND: Hyperbilirubinemia occurs as a sign of hepatic failure after hepatectomy. The pathogenesis of this event has not been elucidated. In cases complicated with postoperative infection, hyperbilirubinemia is prolonged and the composition of bilirubin subfractions in bile changes markedly. A reduction in the proportion of bilirubin diglucuronide (BDG) is especially notable. This study was aimed at clarifying the relationship between infection and biliary bilirubin subfractions, with a view to shedding light on the mechanisms of change. MATERIALS AND METHODS: Rats underwent either laparotomy or partial hepatectomy (Hx). Daily intraperitoneal injections of lipopolysaccharide (LPS) or natural saline were administered for 3 days following surgery. Total serum bilirubin levels and proportions of BDG and bilirubin in bile were measured until Day 5 after the operation. Hepatic levels of UDP-glucuronic acid (UDP-GA), UDP-glucose, NAD(+), and total adenine nucleotides (TAN) and activities of UDP-glucuronyltransferase (UDP-GT) and UDP-glucose dehydrogenase were measured on Day 4. RESULTS: In hepatectomized rats treated with LPS (Hx-LPS), total serum bilirubin levels were elevated, biliary bilirubin levels were decreased, and the proportion of biliary BDG was decreased on Day 4. Hepatic levels of UDP-GA, NAD(+), and TAN and activities of UDP-GT in Hx-LPS were reduced. In all groups tested, a significant linear correlation between BDG and UDP-GA and between UDP-GA and NAD(+) was found. CONCLUSIONS: The reduction of UDP-GA might be effected by reduced hepatic levels of NAD(+) in endotoxemia following hepatectomy. It is therefore suggested that alterations in biliary bilirubin subfractions might accurately reflect the energy state of the remnant liver following hepatectomy.

Adenine Nucleotides↗
PubMed2002

Perineural invasion in pancreatic cancer.

INTRODUCTION: Perineural invasion is regarded as a factor associated with local recurrence of pancreatic cancer. AIM: To examine perineural invasion of pancreatic cancer pathologically and clinically. METHODOLOGY: In 24 cases of surgically resected pancreatic cancer, correlations among the degree of perineural invasion, differentiation, interstitial connective tissue, lymph node metastasis, and survival rate were examined. Consecutive 5-microm serial sections (n = 1072) were made in six cases that showed characteristic mode of perineural invasion. RESULTS: Perineural invasion was observed in 17 cases (70.8%; ne0-7; ne1-6; ne2-9; and ne3-2 cases). Perineural invasion was absent in three of five cases of papillary carcinoma, but was observed in 12 of 14 cases of moderately differentiated carcinoma. The survival rate for ne0 was better than that of the other groups, with the 3-year survival rate being 57.1%. Perineural cancer glands had developed discontinuously in two cases. CONCLUSIONS: Perineural invasion is an important prognostic factor in pancreatic cancer, increasing as the cancer becomes undifferentiated. Even if there are no cancer cells at the margin of the pancreas at the time of surgery, the cancer cells may spread further to the noncancerous pancreas or retroperitoneum. Sufficient dissection of the neural plexus or intraoperative radiation may be required.

Carcinoma, Papillary↗
PubMedDate not supplied

Management of unresectable hilar bile duct cancer--preoperative diagnosis, treatment selection, and clinical outcome.

BACKGROUND/AIMS: Hilar bile duct cancer progresses slowly but easily invades the nearby portal vein or hepatic artery. Thus, in some cases, curative resection is impossible, so we need to determine the best non-surgical treatments for this tumor. METHODOLOGY: We classified 98 patients with hilar bile duct cancer into 3 categories: a non-surgical group (34 cases), an exploratory laparotomy group (9 cases), and a surgical resection group (55 cases). Survival rates were examined in the light of clinical factors. RESULTS: In the non-surgical group, extensive vessel invasion was the most common reason for unresectability (13 cases), with broad biliary extension the second most common (11 cases). In the exploratory laparotomy group the most common reason for unresectability was severe vessel invasion (6 cases). Cumulative 1- and 2-year survival rates for patients with unresectable tumors without distant metastasis were 26.9% and 7.2%, respectively. One- and 2-year survival rates for patients with unresectable tumors and with total bilirubin of less than 2 mg/dL on discharge were 36.8% and 9.8%, respectively. The 1-year survival rate with placement of an expandable metallic stent was as high as 55.6%; without the stent it was 7.1% (P = 0.005). Radiation therapy gave a better prognosis than did no radiation (P = 0.01). CONCLUSIONS: Portal and arterial invasion were the principal reasons for unresectability. Use of an expandable metallic stent or radiation therapy, and a total bilirubin level of less than 2 mg/dL on discharge, were factors that enhanced survival in unresectable cases, but distant metastasis, dissemination, and poor general condition or liver function were negative factors for survival.

Aged↗
PubMedDate not supplied

Surgical management of hilar bile duct cancer. Preoperative diagnosis, selection of treatment options and clinical outcome.

BACKGROUND/AIMS: Although the progression of hilar bile duct cancer is slow, without adequate treatment the prognosis becomes poor. Margin-positive or negative resection has often been reported to correlate with the prognosis. Moreover, the value of combined vessel resection for hilar bile duct cancer is still obscure. METHODOLOGY: Fifty-five out of 98 cases of hilar bile duct cancer were treated with surgery. The patients were classified as a microscopic margin-positive resection group with 12 cases and a microscopic margin-negative resection group with 43 cases. The agreement between preoperative diagnosis and pathological findings of resected specimens was examined, as were cumulative survival rates according to clinical and pathological factors. RESULTS: In diagnosis of portal invasion with computed tomography, the rate of coincidence, overestimate and underestimate were 69.8%, 13.2% and 17.0%, respectively. Corresponding rates in diagnosing arterial invasion were 58.5%, 15.1% and 26.4%, respectively, and for lymph node metastasis 54.7%, 9.4% and 35.8%, respectively. The 5-year survival rates for margin-positive and negative resection groups were 17.9% and 26.5%, respectively (NS). Patients surviving for more than 1 year in the margin-positive resection group tended to exhibit exposed cancer cells only at the bile duct, rarely showing lymph node metastases. Combined arterial resection had a poor prognosis and high, usually lethal, complication rates. CONCLUSIONS: Accurate preoperative diagnosis rates of vessel invasion and lymph node metastasis were 60-70% and 56%, respectively. The long-term survival was expected even in margin-positive resection cases without lymph node metastasis. Combined hepatic arterial resection showed no clinical advantage.

Aged↗
PubMedDate not supplied

Surgical anatomy of the inferior vena cava ligament.

BACKGROUND/AIMS: The inferior vena cava ligament is a fibrous membrane located around the inferior vena cava. Few reports exist on the ligament's location, attachment to the liver, or the inferior vena cava. METHODOLOGY: We obtained 16 specimens of human liver and inferior vena cava from cadavers. The inferior vena cava ligament was photographed and then dissected for histological examination. Relationships among the ligament, inferior vena cava, and liver were examined microscopically. The numbers and diameters of veins, arteries, and lymph vessels at least 1 mm in diameter were recorded. RESULTS: The cranial margin of the inferior vena cava ligament was ended in a blind loop. The cranial portion above the mid-portion of the Spiegel lobe was thicker than the caudal portion. The ligament was attached to the right and left hepatic veins. The mean length of the right side of the inferior vena cava ligament was 37.0 mm and the mean width 15.6 mm. The inferior vena cava ligament had a mean thickness of 0.8 mm (thin end) and 2.5 mm (thick end). Although the inferior vena cava ligament was usually tightly continuous with the liver capsule, microscopically the attachment between the ligament and the inferior vena cava was loose. The mean number and diameter of veins in the inferior vena cava ligament was 1.0 and 1.4 mm, respectively. The mean number and diameter of arteries was 0.2 and 2.4 mm, respectively. The mean number and diameter of lymphatic vessels was 2.8 and 1.7 mm, respectively. CONCLUSIONS: After dissection of the inferior vena cava ligament, major hepatic veins can be dissected extrahepatically. Because the ligament is wider caudally, the forceps should be inserted caudocranially during separation. Since both the number and diameters of lymphatic vessels in the ligament are large, the ligament should be ligated and cut.

Aged↗
PubMedDate not supplied

Spleen-preserving distal pancreatectomy with preservation of the splenic artery and vein for intraductal papillary-mucinous tumor (IPMT): three interesting cases.

Preservation of the spleen at distal pancreatectomy has recently attracted considerable attention. Since our first trial and success with spleen-preserving distal pancreatectomy with conservation of the splenic artery and vein for tumors of the pancreas and chronic pancreatitis, this procedure has been performed more frequently. Three patients with intraductal papillary-mucinous tumor underwent spleen-preserving distal pancreatectomy with conservation of the splenic artery and vein. In this procedure, the splenic vein is identified behind the pancreas and the connective tissue membrane is cut longitudinally above the splenic vein. An important point is to remove the splenic vein from the pancreas from the body of the pancreas toward the spleen. In one patient with intraductal papillary-mucinous tumor in the body of the pancreas who had undergone distal gastrectomy for duodenal ulcer 32 years previously, residual proximal gastrectomy could be avoided with this procedure. In this case, the histological diagnosis was a pseudocyst, and epithelial dysplasia was found in other pancreatic ductuli. In another case, epithelia were borderline between hyperplasia and adenoma. In both of these cases, the histological diagnosis was different from the preoperative diagnosis. Even with advances in imaging techniques, diagnosis of a cystic lesion of the pancreas is still very difficult. Ordinary distal pancreatectomy with splenectomy would have been oversurgery in these two cases, which could be avoided using our procedure. Severe complications were not found in any of the three cases and the postoperative course was uneventful. The patients have been followed as outpatients without any recurrence. Spleen-preserving distal pancreatectomy with conservation of the splenic artery and vein is easy and safe, and should be performed for some patients with intraductal papillary mucinous tumor of the pancreas.

Adenocarcinoma, Mucinous↗
PubMedDate not supplied

Spleen-preserving distal pancreatectomy for intraductal papillary-mucinous tumor (IPMT).

BACKGROUND/AIMS: Recently, the significance of preserving the spleen has received a lot of attention. Since our first trial and success of spleen-preserving distal pancreatectomy with conservation of the splenic artery and vein for chronic pancreatitis, this procedure has been more frequently performed and reported. In this study, we introduce the technique and indications for the procedure for intraductal papillary mucinous tumor of the pancreas. METHODOLOGY: Nine patients underwent spleen-preserving distal pancreatectomy with conservation of the splenic artery and vein. We performed this procedure in two patients with intraductal papillary mucinous tumor. The splenic vein is identified behind the pancreas and within the thin connective tissue membrane. The connective tissue membrane is cut longitudinally above the splenic vein. An important technique is to remove the splenic vein from the pancreas from the body of the pancreas toward the spleen. There are many branches from the splenic vein on both sides, and these branches should be carefully ligated and cut. The pancreas is removed from the splenic artery from the spleen toward the head of the pancreas. This procedure is much easier than removing the pancreas from the vein. RESULTS: The postoperative course was uneventful in all nine cases, but one, in which pancreatic fistula continued for more than several weeks. The mean and standard deviation of the operative blood loss, the duration of the operation and the postoperative hospital stay in seven cases, excluding two cases, in which either Puestow's procedure or simultaneous subtotal esophagectomy was performed, were 413+/-385 mL, 298+/-55 min, and 39+/-15 days, respectively. Severe complications were not found in any of the nine cases. The two patients with intraductal papillary mucinous tumor have been followed as outpatients without any recurrence. CONCLUSIONS: Spleen-preserving distal pancreatectomy with conservation of the splenic artery and vein is easy and safe, and should be performed for some of the patients with intraductal papillary mucinous tumor of the pancreas.

Adult↗
PubMedDate not supplied

Surgical management for metastatic liver tumors.

BACKGROUND/AIMS: This study investigated the results of hepatectomy for multiple liver metastases and repeated hepatectomy for recurrent hepatic metastases. A proposed treatment strategy for liver metastases is discussed. METHODOLOGY: Fifty-seven consecutive cases of liver metastases were studied. The metastases originated from colon cancer (24 cases), rectal cancer (11 cases), gastric cancer (14 cases), or gastrointestinal stromal tumors (two cases). The other cases included one each of gastric carcinoid, carcinoma of the papilla of Vater, cystic duct cancer, esophageal cancer, choriocarcinoma and breast cancer. RESULTS: The overall 5-year survival rate for the 57 cases was 45.4%; there was no significant difference between patients with colon cancer (56.3%), rectal cancer (45.5%), or gastric cancer (41.6%). The cumulative 5-year survival rates for synchronous and metachronous metastases were 38.3% and 50.8%, respectively (difference not statistically significant; NS). The survival rates for single and multiple metastases were 56.0% and 31.3% (NS), and those for monolobar and bilobar metastases were 48.5% and 40.9% (NS), respectively. Concerning the operative procedure, the survival rates for partial resection and hemi-hepatectomy were 49.5% and 26.9%, respectively (NS). The survival rates for surgical margins <4mm and >5mm were 45.9% and 45.4%, respectively (NS), and those for single and repeat hepatectomy were 40.5% and 58.2% (NS). Preoperative portal embolization was performed in seven cases because of multiple metastases or a tumor located in a deeper site in the liver. There was no hospital death among the 57 cases. CONCLUSIONS: These results show that hepatectomy may offer longer survival, even in patients with multiple or bilobar metastases. Neither the operative procedure nor the size of the surgical margin had any influence on survival after hepatectomy. The prognosis was improved not only for metastases from colorectal cancer, but also for gastric cancer. An increased survival benefit was obtained by repeat hepatectomy for recurrent hepatic metastases. Preoperative portal embolization extended the indication for hepatectomy and provided postoperative safety.

Adult↗