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Biomedical subjects

T Satoh

Publications and source records attributed to T Satoh.

At least 505 records · Page 28Linked to original sources
PubMed1996

Autotrophic carbon dioxide fixation in Acidianus brierleyi.

The autotrophic CO2 fixation pathway in Acidianus brierleyi, a facultatively anaerobic thermoacidophilic archaebacterium, was investigated by measuring enzymatic activities from autotrophic, mixotrophic, and heterotrophic cultures. Contrary to the published report that the reductive tricarboxylic acid cycle operates in A. brierleyi, the enzymatic activity of ATP:citrate lyase, the key enzyme of the cycle, was not detected. Instead, activities of acetyl-CoA carboxylase and propionyl-CoA carboxylase, key enzymes of the 3-hydroxypropionate cycle, were detected only when A. brierleyi was growing autotrophically. We conclude that a modified 3-hydroxypropionate pathway operates in A. brierleyi.

Acetyl-CoA Carboxylase↗
PubMed1996

Effects of beta-lactam antibiotics on intestinal microflora and bile acid metabolism in rats.

Wistar male rats were treated for six days with broad spectrum beta-lactam antibiotics, latamoxef, and cefotaxime. On the seventh day, the number of fecal anaerobic microbes decreased, total fecal bile acids decreased, and bile acid pools increased. Secondary bile acids such as beta-hyocholic, hyodeoxycholic, lithocholic, and deoxycholic acids decreased in the feces while the primary bile acids, cholic, beta-muricholic, and chenodeoxycholic acids, became predominant. Coprostanol, a microbial metabolite of cholesterol, also disappeared from the feces during the treatment. The cecum enlarged to almost twice the size of that in control rats, whereas the liver weight was not significantly changed. After treatment was stopped, the number of fecal microbes returned to the initial counts within a week, but restoration of bile acid and cholesterol metabolism required at least three weeks.

Animals↗
PubMed1996

Regulation of Na-K-ATPase activity in the proximal tubule: role of the protein kinase C pathway and of eicosanoids.

To evaluate further the signal transduction mechanisms involved in the short-term modulation of Na-K-ATPase activity in the mammalian kidney, we examined the role of phospholipase C-protein kinase C (PLC-PKC) pathway and of various eicosanoids in this process, using microdissected rat proximal convoluted tubules. Dopamine (DA) and parathyroid hormone (either synthetic PTH1-34 or PTH3-34) inhibited Na-K-ATPase activity in dose-dependent manner; this effect was reproduced by PKC530-558 fragment and blocked by the specific PKC inhibitor calphostin C, as well as by the PLC inhibitors neomycin and U-73122. Pump inhibition by DA, PTH, or arachidonic acid, and by PKC activators phorbol dibutyrate (PDBu) or dioctanoyl glycerol (DiC8) was abolished by ethoxyresorufin, an inhibitor of the cytochrome P450-dependent monooxygenase pathway, but was unaffected by indomethacin or nordihydroguaiaretic acid, inhibitors of the cyclooxygenase and lipoxygenase pathways of the arachidonic acid cascade, respectively. Furthermore, each of the three monooxygenase products tested (20-HETE, 12(R)-HETE, or 11,12-DHT) caused a dose-dependent inhibition of the pump. The effect of DA, PTH, PDBu or DiC8, as well as that of 20-HETE was not altered when sodium entry was blocked with the amiloride analog ethylisopropyl amiloride or increased with nystatin. We conclude that short-term regulation of proximal tubule Na-K-ATPase activity by dopamine and parathyroid hormone occurs via the PLC-PKC signal transduction pathway and is mediated by cytochrome P450-dependent monooxygenase products of arachidonic acid metabolism, which may interact with the pump rather than alter sodium access to it.

Amiloride↗
PubMed1996

The effects of pravastatin, an HMG-CoA reductase inhibitor, on cell viability and DNA production of rat hepatocytes.

Some metabolites and products of mevalonic acid are involved in various cellular functions, particularly cell growth. In this study, we assessed the effects of pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on cell viability and DNA production of rat hepatocytes stimulated with epidermal growth factor. Pravastatin (0.1 to 10 microM) induced a dose-dependent reduction of DNA synthesis, assessed by 3H-thymidine incorporation in rat hepatocytes, which dropped by approximately 60% at a drug concentration of 10 microM. This suppression of DNA synthesis was nearly reversed by exogenous mevalonic acid, but was not prevented by purified low-density lipoprotein cholesterol. Pravastatin did not affect the mitochondrial reduction of Dimethylthiazolyl-diphenyl-tetrazolium bromide (MTT), but induced apoptotic change as assessed by nuclear chromatin staining. This apoptotic change was also reversed by exogenous mevalonic acid. These results indicate that mevalonic acid metabolites are necessary for DNA synthesis by rat hepatocytes stimulated by epidermal growth factor and for suppressing cell death.

Adenine↗
PubMed1996

Molecular cloning and characterization of the putative ultraviolet-sensitive visual pigment of goldfish.

A cDNA full length encoding a putative ultraviolet (UV)-sensitive visual pigment of goldfish was isolated. The deduced amino acid sequence shows 64% identity to those of human blue and chicken violet, and less identity (40-49%) to those of other vertebrate visual pigment. The mRNA is localized in the miniature short single cone cells, which are known to have a sensitivity maximum in the near UV-region.

Amino Acid Sequence↗
PubMed1996

Large diffuse arteriovenous malformation affecting the right cerebral and cerebellar hemispheres: case report.

A cerebral vascular malformation was triggered in a 24-year-old man by left hemiparesis resembling transient ischemic attack. Cerebral angiography revealed slight dilation of the right anterior cerebral artery, middle cerebral artery, superior cerebellar artery, and posterior inferior cerebellar artery, as well as marked capillary blush and dilation of medullary veins involving the right cerebral hemisphere, especially the frontal lobe and cerebellar hemispheres. This vascular malformation, a clinical rarity, seemed to be in the same family as diffuse arteriovenous malformation or "medullary venous malformation." Single photon emission computed tomography showed a decline in cerebral blood flow in the right cerebral hemisphere, which was the probable cause of the left hemiparesis.

Adult↗
PubMed1996

Lymphocyte activation effect of (1-->6)-2,5-anhydro-D-glucitol and it derivatives with 3,4-di-O-methyl and sulfate groups.

(1-->6)-2,5-Anhydro-3,4-di-O-methyl-D-glucitol (2a) and (1-->6)-2,5-anhydro-D-glucitol (2c) and its sulfated derivative (2d) were synthesized and their biological activities were evaluated in regards to the effects on murine lymphocytes. The polymers showed different effects on the lymphocytes depending on the substituent groups. The sulfated polymer (2d) induced mitogenic activities, and specifically activated the CD4(-)CD8(-) subset of lymphocytes.

Animals↗
PubMed1996

Electrophysiologic effects of ischemic preconditioning on QT dispersion during coronary angioplasty.

OBJECTIVES: The aim of this study was to examine the effect of ischemic preconditioning on the manner of ventricular repolarization by assessing the change in QT dispersion during coronary angioplasty. BACKGROUND: QT interval dispersion reflects regional variations in ventricular repolarization and cardiac electrical instability. Previous studies have suggested that increased QT dispersion is associated with an increased incidence of malignant ventricular arrhythmias, whereas brief episodes of myocardial ischemia can render the heart more resistant to subsequent ischemic episodes, a phenomenon called ischemic preconditioning. METHODS: To assess the effects of ischemic preconditioning on myocardial repolarization by examining the change in QT dispersion during coronary angioplasty, we studied 47 consecutive patients (39 men and 8 women; mean age 57 +/- 16 years). QT dispersion was measured after each balloon inflation during coronary angioplasty. Statistical analysis was performed by using repeated measurement of analysis of variance. RESULTS: There were significant differences in QT dispersion as the number of balloon inflations increased (mean +/- SD 52 +/- 14, 42 +/- 11, 36 +/- 9, 31 +/- 10 and 29 +/- 11 ms, respectively [p < 0.01], for the first, second, third, fourth and fifth balloon inflations). The magnitude of decrease in QT dispersion was significant in the first and second balloon inflations, then became insignificant with later inflations. CONCLUSIONS: These data indicate that the gradual decrease in QT dispersion provoked by coronary artery occlusion and reperfusion during coronary angioplasty may be associated with electrophysiologic effects of ischemic preconditioning on myocardium in the human heart.

Angioplasty, Balloon, Coronary↗
PubMed1996

Production of chemotactic factor(s) of Langerhans cells by lymph node cells in contact sensitivity.

Langerhans cells (LCs) have to leave the epidermis to migrate into the regional lymph node (LN) after receiving immunogenic signals in contact sensitivity. There should be some molecules responsible for migration of LC in this process. In order to determine whether LN cells can generate such regulatory molecules, we made a search of such molecules in the culture supernatant of LN cells obtained from hapten-painted mice by using a modified Boyden chamber method. The molecule of LC chemotaxis appeared in the culture supernatant at 24 h after hapten painting and its production declined with time thereafter. Antibodies against both ICAM-1 and LFA-1 partially inhibited the chemotactic activity, but this was not the case with anti-TNF-alpha antibody, anti-GM-CSF antibody, fibronectin RGDS. RGES peptide or laminin. The molecule was heat labile and appeared as a molecule of 45-68 kDa on high performance liquid chromatography. Our results suggest that LN cells generate one of the chemotactic molecules of LCs, by which LC can migrate to the regional LN in contact sensitivity.

Animals↗
PubMed1996

Mechanism of tachycardia-dependent appearance of ventricular extrasystoles in concealed bigeminy.

A case of concealed ventricular bigeminy is reported in which the number of sinus QRS complexes intervening between two successive noninterpolated extrasystoles was always uneven. Coupling intervals of manifest extrasystoles to the preceding sinus QRS complexes were almost fixed and much longer than sinus QT intervals. Bradycardia-dependent disappearance of manifest bigeminy and tachycardia-dependent appearance of extrasystoles occurred in this case. Apparently, 2:1 block of sinus impulses occurred in the reentrant pathway, with markedly depressed conductivity. Concealed electrotonic conduction of blocked sinus impulses in the pathway of extrasystoles may have favored the appearance of the subsequent manifest extrasystoles without concealed conduction owing to two-level block. A possible explanation for the mechanism of such concealed bigeminy is presented, which uses the concepts of longitudinal dissociation and electrotonic inhibition in the reentrant pathway with markedly depressed conductivity.

Adult↗
PubMed1996

Ventricular tachycardia with narrow QRS duration, a right bundle branch block pattern, and right axis deviation abolished by catheter manipulation.

A 25-year-old women underwent electrophysiologic evaluation for sustained normal QRS complex tachycardia with a pattern of right bundle branch block and right axis deviation. Ventricular tachycardia was diagnosed by demonstrating fusion beats, atrioventricular dissociation, and bundle of His potential activation, which began before the onset of each QRS complex. A single ventricular extrastimulus was capable of easily provoking the tachycardia. There was an inverse relationship between the coupling interval of the first extrastimulus and the interval of the first tachycardia beat, suggesting reentry as the mechanism. The tachycardia was unexpectedly abolished during catheter manipulation in the left ventricle and has never recurred during 1 year of follow-up evaluation. The tachycardia was thought to be an unusual form of interfascicular tachycardia or microreentrant fascicular tachycardia.

Adult↗
PubMed1996

Deoxyribonucleic acid ploidy status as no basis for pathologic stage prediction in clinically resectable prostate cancer.

OBJECTIVES: Assessment of deoxyribonucleic acid (DNA) ploidy status of a tumor as a means for predicting pathologic stages in prostate cancer. METHODS: DNA ploidy of each focus of a cancer in 70 radical prostatectomy specimens was determined by nuclear image analysis. DNA ploidy was compared with the pathologic features of tumors. RESULTS: One hundred three individual cancers in 70 patients were used for DNA ploidy analysis. Of these, 39 (38%) were diploid and 64 (62%), nondiploid. DNA ploidy was weakly correlated with increase in tumor volume (P = 0.049) but not tumor grade. The relationship between DNA content and extraprostatic spread was not statistically significant. Increase in tumor volume and grade promoted extraprostatic spread more than nondiploidy, as shown by multivariate analysis. CONCLUSIONS: The incidence of a nondiploid cell population in a tumor focus in prostate cancer is essentially the same, at least for Americans and Japanese. DNA ploidy of a tumor cannot serve as a means of pathologic stage prediction in clinically resectable prostate cancers, contrary to many previous studies. Thus, DNA content analysis would be of no use for deciding on the treatment strategy of prostate cancer.

DNA, Neoplasm↗
PubMed1996

Free radical-independent protection by nerve growth factor and Bcl-2 of PC12 cells from hydrogen peroxide-triggered apoptosis.

To investigate the mechanism of oxidative stress induced death of PC12 cells, we performed confocal and flow cytometric analysis with a reactive oxygen species (ROS)-specific fluorogen, 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate, di(acetoxymethyl ester) (C-DCDHF-DA). Hydrogen peroxide significantly decreased the number of viable PC12 cells after 24 h. Hydrogen peroxide caused membrane blebbing, nuclear condensation and DNA fragmentation, indicating that the PC12 cells died due to apoptosis. The hydrogen peroxide-triggered apoptosis of PC12 cells was associated with enhanced ROS production in a dose-dependent manner by measuring with C-DCDHF-DA. Nerve growth factor (NGF) and Bcl-2 inhibited the hydrogen peroxide-induced apoptosis of PC12 cells. Neither of them, however, reduced the ROS production in PC12 cells. These data suggest that NGF or Bcl-2 protects PC12 cells from hydrogen peroxide-triggered apoptosis independently from ROS production.

Animals↗
PubMed1996

Significance of preoperative parameters for predicting tumor volume in nonpalpable prostate cancer.

Preoperative parameters were assessed for their usefulness in predicting tumor volume in 26 cases of nonpalpable prostate cancer. The number of positive biopsy cores was found to be the parameter which predicted most accurately tumor volume in surgical specimens. All 14 patients with multiple positive cores had an index tumor of 0.5 cm3 or more in radical prostatectomy specimens. Only six tumors with a single positive core were substantial. Three of the patients showed a serum level of prostate specific antigen (PSA) of 4.0 ng/ml or more. The pathological stage and prostatectomy Gleason sum could not be predicted accurately by this variable (P>0.05). To predict index tumor volumes of 1.0 cm3 or greater, stepwise logistic regression analysis was conducted, and on the basis of the results it was possible to single out multiple positive biopsies as the only significant variable. The number of positive biopsies appeared reliable for predicting tumor volume of surgical specimens in cases of nonpalpable disease. The presence of significant tumors despite "normal" levels of PSA warrants further investigation of variables that can predict such prostate cancers. An adequate model for predicting significant tumors in oriental male populations should be established using samples of larger size.

Biopsy, Needle↗
PubMed1996

Preoperative serum prostate-specific antigen, clinical stage and Gleason sum as basis for predicting final pathological stage in Japanese patients with prostate cancer.

By logistic regression analysis and log-likelihood ratio chi-square test, the usefulness of preoperative variables (prostate specific antigen [PSA], clinical stage and biopsy Gleason sum) for predicting the final pathological stage was assessed in 77 patients with clinically resectable prostate cancers. Pathologically, 32 (41.6%) had organ-confined disease. Extracapsular extension was found in 41 (53.2%), seminal vesicle involvement in 30 (39.0%), positive pelvic lymph nodes in 10 (13.0%) and a positive surgical margin in 27 (35.1%). Each preoperative variable was found to be significantly associated with the final pathological stage. Any combination of these variables was more predictive for extraprostatic disease, compared with each individual variable. Extraprostatic spread was found more frequently in patients with lower serum PSA in this Japanese elderly male population compared with North American males. These preoperative variables considered in combination may provide valuable information for management decisions related to prostate cancer. Serum PSA alone cannot reliably predict pathological stage on an individual basis except in patients with a PSA level of 20 ng/ml or greater. The high incidence of extraprostatic spread at intermediate PSA underscores the importance of selecting an ideal cutoff value for PSA-based screening in a Japanese male population.

Aged↗
PubMed1996

Purification of the cytosolic CuZn-superoxide dismutase (CuZn-SOD) of Marchantia paleacea var. diptera and its resemblance to CuZn-SOD from chloroplasts.

Suspension-cultured cells of Marchantia paleacea var. diptera contain a single form of CuZn-superoxide dismutase (SOD; EC 1.15.1.1) which is localized in the cytosol. SOD activity was found in cells cultured under heterotrophic, photoheterotrophic and photoautotrophic conditions. The CuZn-SOD was purified to homogeneity from liverwort cells that had been cultured heterotrophically. Its molecular mass was 32.6 kDa, and it contained 17.5 dDa subunits, an indication that the enzyme is a homodimer. The enzyme had peaks of absorption at 252, 258 and 264 nm in the ultraviolet region, due to the presence of phenylalanine, and a peak at 680 nm in the visible region, which is characteristic of CuZn-SODs from chloroplasts. The amino acid sequence of the amino-terminal region of the enzyme exhibited a very high degree of homology to those of chloroplast CuZn-SODs. An antiserum raised against the CuZn-SOD from liverwort cross-reacted more strongly with the enzyme from spinach chloroplasts, than with the enzyme from spinach cytosol. These results indicate that the CuZn-SOD of liverwort resembles CuZn-SOD in chloroplasts even though the former is located in the cytosol.

Amino Acid Sequence↗