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J Sakamoto

Publications and source records attributed to J Sakamoto.

At least 19 recordsLinked to original sources
PubMed1996

Cytochrome bd-type quinol oxidase in a mutant of Bacillus stearothermophilus deficient in caa3-type cytochrome c oxidase.

Gram-positive thermophilic Bacillus species contain cytochrome caa3-type cytochrome c oxidase as a terminal oxidase in the respiratory chain. To identify alternative oxidases, we isolated B. stearothermophilus mutants defective in the caa3-type oxidase activity. One mutant contained little cytochrome a and had low cytochrome c oxidase activity. However, growth and the respiratory activity of membranes in the presence of NADH were close to normal, suggesting that the mutant contains an alternative electron transfer pathway. A novel oxidase was isolated from the membrane fraction of the mutant. The enzyme is a cytochrome bd-type quinol oxidase composed of two subunits of 52 and 40 kDa, whose N-terminal regions show sequence similarity to polypeptides of the bd-type oxidase from Escherichia coli and Azotobacter vinelandii. This is the first report of a bd-type terminal oxidase purified from a Gram-positive bacterium.

Amino Acid Sequence↗
PubMed1996

Prognostic value of preoperative immunosuppressive acidic protein in patients with gastric carcinoma. Findings from three independent clinical trials. Tumor Marker Committee for the Study Group of Immunochemotherapy with PSK for Gastric Cancer.

BACKGROUND: Immunosuppressive acidic protein (IAP) has been reported to have close correlation with the impairment of host immune response. To evaluate the significance of IAP in clinical studies, the prognostic value of preoperative IAP was investigated in clinical trials of patients with gastric carcinoma after curative resection. METHODS: An appropriate IAP threshold value of 580 micrograms/mL was determined using Cox's proportional hazards model. Five-year survival rates were estimated for high and low IAP groups in three different clinical studies. Meta-analysis was performed based on individual patient data, and summarized hazard ratios were estimated using a stratified proportional hazards model. RESULTS: Meta-analysis of the three clinical trials demonstrated that patients with preoperative IAP levels above the threshold had significantly poorer cancer related survival (P = 0.0039) and absolute survival (P = 0.0023), even after adjustment for the major prognostic factors. CONCLUSIONS: Gastric carcinoma patients with an IAP value above the threshold level of 580 micrograms/mL have a higher risk of cancer death and absolute death than patients with an IAP value below the threshold value.

Adult↗
PubMed1996

Nucleotide and amino acid sequences for cytochrome caa3-type oxidase of Bacillus stearothermophilus K1041 and non-Michaelis-type kinetics with cytochrome c.

A pseudo-sigmoidal cytochrome c-dependence curve of oxidase activity was observed with cytochrome oxidase from the Bacillus stearothermophilus strain K1041, while the other thermophilic Bacillus PS3 which has been extensively studied possessed normal Michaelis-Menten type kinetics. The genes coding for four subunits of cytochrome caa3-type oxidase and for heme O synthase were isolated from a genomic DNA library of K1041 by using a PS3 DNA fragment containing the highly-conserved region of the largest subunit as a probe, and sequenced. Most residues in subunits I (COI/caaB product), III (COIII/caaC product), and IV (COIV/caaD product) of K1041 were highly conserved when compared with those of PS3. However, the sequence of K1041 subunit II (COII/caaA product) was distinctly different from that of the PS3 subunit II. These Bacillus COIIs have an additional sequence for cytochrome c after the CuA binding protein portion with two transmembrane segments which is homologous to the mitochondrial counterpart, and represents the site of electron ingress. Several charged residues in the vicinity of cytochrome c moiety are replaced by oppositely charged residues. It is likely that these amino acid replacements in subunit II are the cause of the abnormal sigmoidal saturation curve for extrinsic cytochromes c of the K1041 enzyme.

Amino Acid Sequence↗
PubMed1996

Immunohistochemical analysis of the poorly differentiated stomach adenocarcinoma with medullary growth pattern.

Poorly differentiated gastric adenocarcinoma with medullary features (poor medullary) is distinguished by a propensity for hepatic metastasis. To classify it antigenically, we compared it to poorly differentiated adenocarcinoma with scirrhous growth pattern (poor scirrhous), well and moderately differentiated adenocarcinoma (differentiated adenocarcinoma), and normal gastric mucosa (foveolar and deep epithelium) using immunohistochemistry with antibodies against CEA, AFP, NSE, and Lewis-type antigens. Lewis(a) antigen was significantly associated with differentiated adenocarcinoma and foveolar epithelium, although Lewis(x) antigen was significantly expressed in poor medullary, poor scirrhous, and deep gland epithelium. From the viewpoint of expression of Lewis(a), there was no significant differentiation between poor medullary and differentiated adenocarcinoma, but it was definite between poor scirrhous and differentiated adenocarcinoma. Therefore, we conclude that in antigenic expression, poor medullary carcinoma is allied with differentiated adenocarcinoma rather than poorly differentiated scirrhous carcinoma.

Adenocarcinoma↗
PubMed1996

Preoperative embolization of gastric arteries for esophageal cancer.

BACKGROUND: We developed a novel treatment of preoperative embolization therapy in an attempt to prevent anastomotic leakage after esophageal resection. We report the results of this new treatment. METHODS: Preoperative embolization therapy (PET) was performed in 24 cases of esophageal carcinoma. The femoral artery was punctured, and celiac angiography was performed. The left gastric artery and splenic artery underwent embolization. The right gastric artery then underwent embolization at a site beyond the second or third branch to the gastric wall. With a laser flow meter the stomach tissue blood flow was measured before and after construction of the gastric tube, and the change in blood flow was compared. RESULTS: The average decrease in gastric blood flow was 23% in patients with PET and 65% in patients without PET. Twenty-one (88%) of 24 cases maintained more than 50% tissue blood flow in patients with PET and in 1 (8%) of 12 in patients without PET (p < 0.001 by t test). No serious complications occurred. CONCLUSIONS: Preoperative embolization therapy is a safe and uncomplicated technique, and tissue blood flow in the stomach was better preserved. This new technique is expected to reduce the frequency of anastomotic leakage after esophageal operation.

Adult↗
PubMed1996

Comparison of resistant starch with cellulose diet on 1,2-dimethylhydrazine-induced colonic carcinogenesis in rats.

BACKGROUND & AIMS: Epidemiological and experimental studies have shown that dietary fiber may prevent colon cancer. Resistant starch, like dietary fiber, is not subject to digestion in the small intestine. However, it is unknown whether resistant starch inhibits colonic carcinogenesis. In vitro studies have shown that butyrate slows the growth of cultured colon cancer cells. The effect of resistant starch diet on 1,2-dimethylhydrazine-induced colonic carcinogenesis in rats was evaluated, and the colonic butyrate concentration was measured. METHODS: Sprague-Dawley rats were randomly divided into five groups that were fed diets containing no fiber, 3% cellulose, 10% cellulose, 3% resistant starch, or 10% resistant starch. Colonic carcinogenesis and butyrate concentration of colonic contents and feces in each diet group were compared. RESULTS: Total cancer volume per rat in the 10% cellulose group was significantly lower than that in the basal group (109 +/- 54 mm3 and 247 +/- 83 mm3; P < 0.05), but the other groups showed no significant differences. The butyrate concentration in colonic content and in feces were higher in the resistant starch groups than in the cellulose groups. CONCLUSIONS: The resistant starch diet increased butyrate concentration but did not inhibit colonic carcinogenesis. It remains doubtful whether butyrate inhibits the proliferation of colon cancer cells.

1,2-Dimethylhydrazine↗
PubMed1996

Intra- and inter-complex cross-linking of subunits in the quinol oxidase super-complex from thermophilic Bacillus PS3.

Gram-positive thermophilic Bacilli contain quinol-cytochrome c reductase and cytochrome c oxidase as two major respiratory complexes of the electron transfer chain, and these enzymes can be extracted with mild detergents as an associated quinol oxidase super-complex. The reductase is composed of three subunits; cytochrome b6, cytochrome c1, and FeS protein, whereas cytochrome c oxidase consists of four subunits numbered 1 through 4. In order to clarify the interactions between the subunits, the super-complex isolated from Bacillus PS3 was cross-linked with three bifunctional cross-linkers; disuccinimidyl tartrate, 3,3'-dithiobis(succinimidylpropionate), and ethylene glycolbis(sulfosuccinimidylsuccinate). The most prominent cross-linking was observed for the combination of subunit 1 plus 2 in cytochrome c oxidase, and for that of cytochrome b6 plus cytochrome c1 in the reductase. In addition to these intra-complex cross-linkings, inter-complex linking was observed for the combination of cytochrome b6 plus subunit 1 with ethylene glycolbis(sulfosuccinimidylsuccinate), and for the combinations of cytochrome b6 plus subunit 1 and cytochrome b6 plus subunit 2 with 3,3'-dithiobis(succinimidylpropionate). Incubation in the presence of Triton X-100, which was confirmed to cleave the two enzyme complexes, selectively reduced the inter-complex cross-linking, suggesting that the chemical cross-linking reflect the spatial arrangement of subunits in the super-complex.

Bacillus↗
PubMed1995

Glibenclamide, a blocker of ATP-sensitive potassium channels, abolishes infarct size limitation by preconditioning in rabbits anesthetized with xylazine/pentobarbital but not with pentobarbital alone.

The role of ATP-sensitive potassium channels (KATP) in the mechanism of ischemic preconditioning (PC) is controversial, partly because descriptions of inhibition of PC by KATP blockers in the literature are inconsistent. We sought a reason for the discrepant findings regarding the effects of glibenclamide (Glib), a specific blocker of KATP, in preventing the reduction of infarct size (IS) induced by PC. The effect of Glib pretreatment (0.3 mg/kg i.v.) on PC was examined in three conditions: (a) when PC was performed with 3- and 5-min ischemia (i.e., potency of PC differs), (b) when rabbits were pretreated with prazosin and metoprolol (0.15 mg/kg i.v. each) to reduce myocardial O2 consumption, and (c) when xylazine was added to pentobarbital anesthesia. In rabbits under pentobarbital anesthesia, the left coronary artery was occluded for 30 min and then reperfused. The area at risk (AAR) and IS were determined 72 h after reperfusion in the first series of experiments and 3 h after reperfusion in the second and third series. IS as a percentage of AAR (%IS/AR) were 31.7 +/- 2.8 and 19.6 +/- 2.5% (SEM) after PC with 3- and 5-min ischemia, respectively, values significantly smaller than %IS/AR in the untreated control group (49.2 +/- 3.3%). The limitation of IS observed with 3- or 5-min PC was not prevented by Glib. Glib also failed to block %IS/AR reduction by PC, even when rate-pressure product (RPP) was reduced to approximately 65% by prazosin/metoprolol (Praz/Met) pretreatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1995

Limitation of myocardial infarct size by adenosine A1 receptor activation is abolished by protein kinase C inhibitors in the rabbit.

OBJECTIVE: The aim was to test whether infarct size limitation by adenosine A1 receptor activation is mediated by protein kinase C. METHOD: In the first series of experiments, myocardial infarction was induced in rabbits under pentobarbitone anaesthesia by 30 min coronary artery occlusion and 3 h reperfusion. Rabbits were pretreated with no drugs (control). 1 mg.kg-1 of R(-)N6-2-phenylisopropyl adenosine (PIA), 50 micrograms.kg-1 of staurosporine (Stauro), 2.5 mg.kg-1 of polymyxin B (PolyB), and a combination of PIA and either Stauro or PolyB. Infarct size and the area at risk were determined by tetrazolium staining and fluorescent particles, respectively. In the second series of experiments, the inotropic response to 4 beta-phorbol 12-myristate 13-acetate (PMA) was assessed in rabbits with and without pretreatment using the same doses of Stauro and PolyB as those in the first series of experiments. RESULTS: Infarct size expressed as percent of area at risk (%IS/AR) was significantly smaller in the PIA treated group than in the control: %IS/AR = 19.0(SEM 2.4)% v 37.7(4.0)%, P < 0.05. However, %IS/AR in the groups given Stauro [35.0(4.2)%], PolyB [37.9(3.2)%], PIA plus Stauro [34.9(3.9)%], and PIA plus PolyB [36.3(3.3)%] did not differ from the control value. PMA at the dose of 0.02 and 0.05 micrograms.kg-1 caused a dose dependent increase of the left ventricular dP/dtmax in the untreated rabbits. Such a positive inotropic response to PMA was not detected in rabbits pretreated with Stauro or PolyB, suggesting that the doses of the protein kinase C inhibitors were appropriate to block protein kinase C in the heart. CONCLUSIONS: Infarct size limitation by A1 receptor stimulation is mediated by activation of protein kinase C in pentobarbitone anaesthetised rabbits.

Alkaloids↗
PubMed1995

Evaluation of the effect of pancreatic resection in advanced pancreatic cancer with special reference using hospital-free survival as a measure of quality of life.

Comparisons of surgical procedures and the identification of prognostic factors in pancreatic cancer were carried out on 158 patients who underwent surgery in Aichi Cancer Center from 1975 to 1991 for advanced pancreatic ductal adenocarcinoma. Survival and 'hospital-free survival (HFS), which we consider the best general means of measuring quality of life (QOL) in such severe and often fatal disease, were identified as primary end points, and the effect of pancreatectomy, compared with palliative surgery (by-pass operation, etc.) for TNM Stages III and IV pancreatic cancer was evaluated. Both survival and HFS were significantly longer in the group of patients who underwent pancreatectomies (R group, n 25) compared to the group without pancreatic resection (NR group, n 35) in Stage III cases. In Stage IV cases, however, no significant difference was observed between the R (n 12) and NR (n 86) groups. From these results, we conclude that an extensive pancreatic resection against Stage III pancreatic cancer may improve prognosis. For Stage IV pancreatic cancers, however, aggressive surgery might not always be beneficial either for survival or for QOL.

Carcinoma, Ductal, Breast↗
PubMed1994

Over-expression of membrane-bound cytochrome c-551 from thermophilic Bacillus PS3 in Bacillus stearothermophilus K1041.

Cytochrome c-551 is a lipoprotein of about 10500 Da, found in thermophilic Bacillus PS3 grown under air-limited conditions. An expression vector was constructed from a structural gene of PS3 cytochrome c-551, synthetic oligonucleotide as a promoter for Bacillus stearothermophilus and a shuttle vector for Escherichia coli and B. stearothermophilus. The transformed cells of B. stearothermophilus K1041 expressed cytochrome c-551 as much as 5 nmol/mg membrane protein. The effects of over-expression on the host cells are analyzed; a slightly slower growth rate and an increased synthesis of cytochrome oxidase (about twofold) occurred. Over-expressed (4-10-fold) cytochrome c-551 were purified and its properties were examined to know whether the protein is processed as in PS3 cells grown under air-limited conditions. The molecular mass determination and treatment with Rhizopus lipase suggested that the same processes, cleavage of signal peptidase, blocking of the N-terminal group and acylation of glycerol residue by two fatty acids, took place in the over-expression system. Fatty acylation seems useful for the cytochrome c to be effectively oxidized.

Acylation↗
PubMed1994

Efficacy of immunochemotherapy as adjuvant treatment after curative resection of gastric cancer. Study Group of Immunochemotherapy with PSK for Gastric Cancer.

In Japan the standard adjuvant treatment after resection of gastric cancer is intravenous mitomycin plus oral fluorouracil. We have assessed the efficacy of protein-bound polysaccharide (PSK) in addition to standard chemotherapy in patients who had undergone curative gastrectomy at 46 institutions in central Japan. 262 patients were randomly assigned standard treatment alone or with PSK. The minimum follow-up time was 5 years (range 5-7 years). PSK improved both the 5-year disease-free rate (70.7 vs 59.4% in standard treatment group, p = 0.047) and 5-year survival (73.0 vs 60.0%, p = 0.044). The two regimens had only slight toxic effects, consisting of nausea, leucopenia, and liver function impairment, and there were no significant differences between the groups. The treatments were clinically well tolerated and compliance was good. Addition of PSK to adjuvant chemotherapy with mitomycin and fluorouracil is beneficial as treatment after curative gastrectomy.

Adjuvants, Immunologic↗
PubMed1994

Nucleoside transport inhibitors enhance the infarct size-limiting effect of ischemic preconditioning.

We recently observed that dipyridamole pretreatment significantly enhanced the infarct size (IS)-limiting effect of preconditioning (PC), which was attenuated by adenosine receptor antagonist. This potentiation of PC was interpreted to result from inhibition of nucleoside transport by dipyridamole, but contribution of other pharmacologic actions of dipyridamole could not be excluded. To confirm that inhibition of nucleoside transport leads to PC enhancement, we assessed alteration of mild PC by two different nucleoside transport inhibitors, dilazep and R75231, which, unlike dipyridamole, lack action on phosphodiesterase (PDE) and prostacyclin. Myocardial infarction was induced in rabbits by 30-min coronary occlusion and 72-h reperfusion. IS and area at risk (AAR) were determined by histology and fluorescent particles, respectively. Rabbits either were untreated or received dilazep (0.34 mg/kg intravenously, i.v.) or R75231 (0.05 mg/kg i.v.) before coronary occlusion. In other groups of rabbits, PC was conducted with 2-min ischemia and 5-min reperfusion with or without injection of the nucleoside transport inhibitor (0.34 or 0.10 mg/kg dilazep or 0.05 mg/kg of R75231) before PC. IS expressed as percentage of AAR (%IS/AAR) was 43.9 +/- 2.3% (SE) in untreated controls; dilazep (0.34 mg/kg) and R75231 alone did not modify IS (%IS/AAR = 50.6 +/- 4.7 and 42.7 +/- 11.9%, respectively). PC tended to reduce IS (%IS/AAR = 33.3 +/- 3.5%), but the combination of dilazep or R75231 with PC significantly limited %IS/AAR (%IS/AAR = 22.5 +/- 5.0% after low-dose dilazep plus PC, 27.6 +/- 4.9% after high-dose dilazep plus PC, and 19.9 +/- 3.6%, after R75231 plus PC).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Prognostic values of preoperative and postoperative CEA and CA19.9 levels in pancreatic cancer.

Preoperative serum levels of carcinoembryonic antigen (CEA) and/or carbohydrate antigen 19.9 (CA19.9) were measured in 90 patients with advanced pancreatic cancer. CEA antigen was above the cutoff levels of 5.0 ng/ml in 51% of patients and CA19.9 was above the cutoff limit of 37 U/ml in 87% of patients. High preoperative CEA and CA19.9 levels were related to a poor prognosis of the patients. In multivariate analysis, the hazard rate was significantly higher in the high-CEA group (> 2.5 ng/ml) compared to the low-CEA group (< 2.4 ng/ml). An increase in CEA and/or CA19.9 within 1 month after the operation was also significantly related to the hazard rate. This study reconfirms the prognostic importance of preoperative and postoperative CEA and CA19.9.

CA-19-9 Antigen↗