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Biomedical subjects

J Sakamoto

Publications and source records attributed to J Sakamoto.

At least 91 records · Page 5Linked to original sources
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

Pigeons' discrimination of paintings by Monet and Picasso.

Pigeons successfully learned to discriminate color slides of paintings by Monet and Picasso. Following this training, they discriminated novel paintings by Monet and Picasso that had never been presented during the discrimination training. Furthermore, they showed generalization from Monet's to Cezanne's and Renoir's paintings or from Picasso's to Braque's and Matisse's paintings. These results suggest that pigeons' behavior can be controlled by complex visual stimuli in ways that suggest categorization. Upside-down images of Monet's paintings disrupted the discrimination, whereas inverted images of Picasso's did not. This result may indicate that the pigeons' behavior was controlled by objects depicted in impressionists' paintings but was not controlled by objects in cubists' paintings.

Journal Article↗
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↗
PubMed1994

Expression of neural cell adhesion molecule in normal gastric mucosa and in gastric carcinoid tumors.

Expression of neural cell adhesion molecule (NCAM) in the digestive system was studied with NE-150 monoclonal antibody, together with those against Lewis blood group antigens. NE-150 did not react with any of 32 cell lines tested derived from digestive tract cancers. In gastric adenocarcinomas NCAM was not expressed regardless of its differentiation status, while in gastric carcinoids and in other carcinoid tumors of different organs, it was present in all the specimens tested. Among normal tissues, it reacted with the deep gastric gland and the islets of Langerhans. These results suggest that NCAM is one of the most specific markers for gastric carcinoid tumors. It was also suggested that the gastric carcinoid tumor might be derived from NCAM-positive cells in the deep gastric gland. These findings should be exploitable in subgrouping gastric tumors in terms of antigen expression.

Adenocarcinoma↗
PubMed1994

Effects of dietary supplementation with lactosucrose (4G-beta-D-galactosylsucrose) on cecal flora, cecal metabolites, and performance in broiler chickens.

The effects of dietary lactosucrose on cecal flora, cecal metabolites, and performance were studied in eight 20-d-old and eight 62-d-old broiler chickens fed a basal diet (control) or a diet with .15% lactosucrose added. On Day 20 of age, the frequency of occurrence of lecithinase-negative clostridia were decreased (P < .05) by lactosucrose consumption. On Day 62 of age, the numbers of bifidobacteria were increased (P < .05) by lactosucrose consumption, but the counts of lecithinase-positive clostridia, including Clostridium perfringens, bacteriodaceae, and staphylococci, total anaerobic bacteria, and the frequency of occurrence of pseudomonads were decreased (P < .05). No detectable change was observed in counts of other organisms throughout the experimental period. Cecal concentration of ammonia (P < .01), phenol (P < .05), and cresol (P < .05) were decreased on Day 62 of lactosucrose consumption. Acetic acid and butyric acid were increased (P < .01 and P < .05, respectively) on Day 62 of lactosucrose consumption. Environmental ammonia and odor of chicken ceca were greatly reduced by lactosucrose consumption.

Ammonia↗
PubMed1994

[Expression and prognostic indicators of type 1 and type 2 Lewis blood group antigens in colorectal cancers].

The immunohistochemical analysis using the monoclonal antibodies to the blood group antigens was performed on the tissues of 387 colorectal cancers and 307 normal colonic tissues, and the relation between expression of these antigens and prognosis of the patients with stage 2 was also investigated. La, Le(b), and CA 19-9 were used for type 1 antigens, and Le(x), Le(y), and Sialyl Le(x) for type 2, respectively. Expression of Ca 19-9 and Silyl Le(x) remarkably increased in cancers throughout the colorectum. Le(b) and Le(y) were expressed in only 0-17% of the normal distal colon, but in almost colonic tumors. Therefore CA 19-9 and Sialyl Le(x) are tumor-associated antigens in the whole colorectum, and Leb and Le(y) in the distal colon. Expression of CA 19-9 in primary tumor provided more prognostic information and risk of liver metastasis than other Lewis blood group antigens.

Adult↗
PubMed1993

Subunit identification and reconstitution of the N-type Ca2+ channel complex purified from brain.

Calcium channels play an important role in regulating various neuronal processes, including synaptic transmission and cellular plasticity. The N-type calcium channels, which are sensitive to omega-conotoxin, are involved in the control of transmitter release from neurons. A functional N-type calcium channel complex was purified from rabbit brain. The channel consists of a 230-kilodalton subunit (alpha 1B) that is tightly associated with a 160-kilodalton subunit (alpha 2 delta), a 57-kilodalton subunit (beta 3), and a 95-kilodalton glycoprotein subunit. The complex formed a functional calcium channel with the same pharmacological properties and conductance as those of the native omega-conotoxin-sensitive calcium channel in neurons.

Animals↗
PubMed1993

Expression of the CD15 antigen in hepatocellular carcinoma.

Expression of the CD15 antigen, which is one of the adhesion molecules, was studied immunohistochemically to investigate the mechanism of intrahepatic metastasis in 56 hepatocellular carcinomas (HCC). Twenty-nine percent (16 of 56) of the HCC expressed CD15. No noncancerous hepatocytes expressed CD15. CD15-positive HCC had histologic intrahepatic metastasis more often than did CD15-negative HCC; the difference was statistically significant (P < 0.02). The survival rate of patients with CD15-negative HCC was better than that of patients with CD15-positive HCC, although the difference was not statistically significant. The authors speculate that there is a relationship between the expression of CD15 and intrahepatic metastasis in HCC.

Antigens, CD↗