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Biomedical subjects

E Satoh

Publications and source records attributed to E Satoh.

At least 91 records · Page 5Linked to original sources
PubMed1992

On the mechanism of ouabain-induced release of acetylcholine from synaptosomes.

Ouabain (5 x 10(-8)-5 x 10(-4) M) was confirmed to cause a dose-dependent increase in [3H]acetylcholine ([3H]ACh) release, cytosolic free Ca2+ concentration ([Ca2+]i), and 22Na+ uptake in cerebrocortical synaptosomes of rats in the presence of extracellular Ca2+. Ouabain also caused a dose-dependent decrease in membrane potential. In a low-Na+ (10 mM) medium, ouabain failed to increase [3H]ACh release and [Ca2+]i. Tetrodotoxin (10(-6) M) had no effect on the ouabain-induced increase in both [3H]ACh release and [Ca2+]i but abolished the increase in 22Na+ uptake and partially inhibited the depolarizing effect. Verapamil (10(-6)-5 x 10(-4) M) inhibited the ouabain-induced increase in both [3H]ACh release and [Ca2+]i in a dose-dependent manner. Removal of extracellular Ca2+ abolished the effect of ouabain on [Ca2+]i but not on [3H]ACh release and 22Na+ uptake, regardless of the presence or absence of EGTA. In the absence of extracellular Ca2+, 10 mM Mg2+ blocked ouabain-induced [3H]ACh release, which was resistant to verapamil. These results suggest that ouabain can increase ACh release from synaptosomes without the preceding increases in intracellular Ca2+ and/or Na+ content. It seems likely that the removal of extracellular Ca2+ unmasks mechanisms of ouabain action different from those operating in the presence of Ca2+.

Acetylcholine↗
PubMed1992

The effectiveness of the air-powder abrasive device for root planing during periodontal surgery.

The efficacy of the air-powder abrasive device (APAD) in root planing during flap surgery was assessed in vitro and in vivo. Two teeth on which full-thickness flaps were raised underwent root planing by hand-scaling alone and hand-scaling combined with APAD. One tooth extracted prior to surgery underwent unrestricted hand-scaling under a binocular microscope (control). The two teeth root planed in situ and the tooth root planed in vitro were observed by scanning electron microscopy (SEM). Then, 10 patients with periodontitis requiring flap surgery were selected for a clinical study. After raising full-thickness flaps, 29 sites from five patients underwent root planing using hand-scaling combined with APAD, whereas 22 sites from six patients underwent root planing by hand scalers only. SEM revealed that root surfaces planed in situ by hand-scaling combined with APAD were smoother than those root-planed using hand scalers alone. The control tooth surface was as smooth as those submitted to combined root planing. The clinical study showed that sites submitted to combined root planing displayed enhanced attachment level gain and pocket reduction. These results, associated with the shortened instrumentation time, suggest APAD as a useful instrument for root planing during flap surgery.

Air↗
PubMed1992

[Methicillin-resistant Staphylococcus aureus infection in the orthopaedic field].

A retrospective report regarding MRSA infections, related to wards and physicians in the hospital, was carried out. The number of the patients infected by MRSA in every wards was compared. Less patients with MRSA infection ware observed in the orthopaedic ward. An epidemiologic study using culture sampling of MRSA was performed at the isolated room for the patient with MRSA infection. Positive cultures were also detected in several areas in the ward, in addition to that room. Then the infection risk of every places in the hospital was suspected. Four cases of orthopaedic patients with MRSA were described.

Adult↗
PubMed1991

Sexing of rat embryos with antisera specific for male rats.

Male-specific antigenicity (H-Y antigen) of rat embryos has been examined, and the feasibility of sexing rat embryos by use of H-Y antibodies has been studied. Rat H-Y antisera were produced by immunization of female Wistar rats with a homogenate of testes from male Wistar neonates. Male specificity of the antiserum (H-Y antibody) was determined by retention of cytotoxicity to male epidermal cells after absorption with female cells. After cultivation of rat embryos for 5 to 6 hr in the presence of antibody, half of the embryos were arrested at the morula stage. However, these embryos developed into blastocysts after removal of the antiserum, and then they grew into male young in recipient foster mothers. Eighty percent of the embryos that developed to blastocysts in the presence of the antiserum grew into female young.

Animals↗
PubMed1991

Histological changes of the gallbladder and liver after extracorporeal shock wave lithotripsy for gallbladder.

The histological changes of the gallbladder and liver following extracorporeal shock wave lithotripsy (ESWL) were investigated in a canine model. After performing ESWL on human cholesterol stones placed in the gallbladder of 8 dogs, the gallbladder and livers were removed for pathological study. The mucosa of the gallbladder showed erosion and ulceration in three of the eight dogs. Edema and bleeding were found in the stroma of the gallbladder beds. Hemorrhagic necrosis and vacuolar degeneration occurred in liver parenchyma adjacent to the gallbladder bed, but the portal area was fairly well preserved. It can be said that ESWL caused damage to both the liver and the gallbladder, but its effects on the liver may be only slight because of the preservation of the portal area.

Animals↗
PubMed1991

The bialaphos biosynthetic genes of Streptomyces viridochromogenes: cloning, heterospecific expression, and comparison with the genes of Streptomyces hygroscopicus.

The bialaphos resistance gene, bar, was used as a selectable marker to isolate the bialaphos production genes (bap) from the Streptomyces viridochromogenes genome. The S. viridochromogenes bar gene was cloned on overlapping restriction fragments using pIJ680 and pIJ702 in the bialaphos-sensitive host, S. lividans. Although the restriction endonuclease cleavage map of these fragments was not similar to the bap cluster of S. hygroscopicus, the presence and location of bar and four other bap genes as well as a gene required for the transcriptional activation of the cluster (brpA) was demonstrated by heterologous cloning experiments using a series of previously characterized bialaphos-nonproducing S. hygroscopicus mutants. Since recombination-deficient mutants of streptomycetes have not been isolated, restored function provided by cloned homologous DNA results from both recombination (marker rescue) and complementation in trans. In contrast to our previously reported homologous cloning experiments where we were able to define the position of mutant alleles by recombination, in these heterologous cloning experiments we observed little if any recombination between plasmid-cloned genes and the chromosome. As a result, this approach allowed us to define the location and orientation of functional genes using a genetic complementation test. The organization of the clustered S. viridochromogenes bap genes was indistinguishable from the corresponding S. hygroscopicus mutant alleles. The fact that the S. viridochromogenes transcriptional regulatory gene, brpA, functioned in S. hygroscopicus implied that some transcriptional regulatory signals may also be interchangeable. In these two Streptomyces species, which have considerable nucleotide sequence divergence, the complex biochemical and genetic organization of the bialaphos biosynthetic pathway is conserved.

Anti-Bacterial Agents↗
PubMed1991

Immunoblastic lymphadenopathy (IBL)-like T-cell lymphoma in a child.

We report the case of a 14-year-old Japanese boy with peripheral T-cell malignant lymphoma, showing progression from immunoblastic lymphadenopathy (IBL) to overt malignant lymphoma. He suffered recurrent fever, generalized lymphadenopathy, hepatosplenomegaly and maculopapular exanthema. Leukocytosis with eosinophilia and polyclonal hypergammaglobulinemia were observed during the aggressive course of the disease. In the early phase, human immunoglobulin and steroids improved the symptoms but did not induce complete remission, and the patient died one year after the onset of the illness. Four biopsies of lymph nodes revealed progression from IBL to CD4 positive T-cell lymphoma through IBL-like T-cell lymphoma. Though IBL-like T-cell lymphoma is defined as IBL with neoplastic features and overt T-cell malignant lymphoma progressed from IBL-like T-cell lymphoma is excluded from the definition, it may be preferable that such malignant lymphoma as our case should also be included in IBL-like T-cell lymphoma.

Adolescent↗
PubMed1991

Effects of monensin and veratridine on acetylcholine release and cytosolic free Ca2+ levels in cerebrocortical synaptosomes of rats.

Monensin (10(-8)-10(-4) M) caused a dose-dependent increase in the release of [3H]acetylcholine ([3H]ACh) from purified rat cerebrocortical synaptosomes, with an EC50 of approximately 1.6 x 10(-6) M. Extracellular Na+, but not Ca2+, was required for a monensin-induced increase in the release of [3H]ACh. Monensin also increased the cytosolic free Ca2+ concentration ([Ca2+]i) and uptake of 22Na+ in a dose-dependent manner. Monensin continued to cause a dose-dependent increase in [Ca2+]i in the absence of extracellular Ca2+, although an approximately 50% reduction was noted at concentrations of greater than 10(-5) M. The EC50 for the monensin-induced increase in [Ca2+]i was similar to that noted in the release of [3H]ACh. Veratridine exhibited effects similar to those of monensin, but a large portion of the increase in [Ca2+]i and [3H]ACh release was dependent on extracellular Ca2+. Measurements of rhodamine 6G fluorescence indicated that monensin and veratridine caused synaptosomal hyperpolarization and depolarization, respectively. Tetrodotoxin (10(-6) M) completely blocked all the effects of veratridine but had no effect on the activity of monensin. These results suggest that monensin increases the release of ACh at least in part by increasing [Ca2+]i, resulting from the increase in the Na+ influx through tetrodotoxin-insensitive mechanisms in rat cerebrocortical synaptosomes.

Acetylcholine↗
PubMed1991

Mode of action of palytoxin on the release of acetylcholine from rat cerebrocortical synaptosomes.

Palytoxin (PTX; 10(-14)-10(-6) M) caused a dose-dependent increase in the release of [3H]acetylcholine ([3H]ACh), cytosolic free Ca2+ concentration ([Ca2+]i), and uptake of 22Na+ and decrease in membrane potential in rat cerebrocortical synaptosomes. The dose-response curves for the PTX-induced increases in [3H]ACh release and in [Ca2+]i were depressed by removing extracellular Ca2+ or by decreasing extracellular Na+ concentrations. The release of [3H]ACh induced by concentrations of PTX less than 10(-10) M was more dependent on the simultaneous presence of both Ca2+ and Na+ than the release induced by higher concentrations of PTX. The PTX-induced increase both in [3H]ACh release and in [Ca2+]i was almost completely abolished by the combination of Ca2+ deprivation and Na+ concentration reduction. All responses to PTX were highly resistant to 10(-6) M tetrodotoxin. These results suggest that low concentrations of PTX cause depolarization as a result of an increase in Na+ permeability through tetrodotoxin-insensitive channels. This, in turn, increases Ca2+ influx and leads to an increase in the release of ACh. It appears that at high concentrations PTX increases the release of [3H]ACh by directly increasing the influx of Ca2+ into synaptosomes and by releasing Ca2+ from intracellular storage sites via an Na(+)-Ca2+ exchange mechanism.

Acetylcholine↗
PubMed1990

Selective beta 1-receptor full agonists, T-0509 and T-1583, increase the force monophasically and cyclic AMP biphasically in canine ventricular muscle.

In canine right ventricular muscle, we investigated the mechanism of action of the positive inotropic effects of T-0509 and T-1583, derivatives of denopamine, a new selective beta 1-partial agonist. T-1583 has already been characterized as a selective beta 1 full agonist (pD2 = 7.39). T-0509 also behaved as a full agonist (pD2 = 8.27) and its positive inotropic effect was antagonized competitively by atenolol (pA2 = 7.53) and noncompetitively by carbachol, and potentiated by 3-isobutyl-1-methylxanthine. With increasing concentrations of T-0509 (10(-9) to 10(-7) M) and T-1583 (10(-8) to 10(-6) M), cyclic AMP increased and increases reached plateaus approximately 40% above the baseline levels with approximately 10(-7) M T-0509 and approximately 10(-6) M T-1583, at which their positive inotropic effects reached maxima. However, with further increasing concentrations, cyclic AMP again started to increase and increases amounted to approximately 120% above the baseline levels with 10(-5) M T-0509 and with 10(-4) M T-1583. These results suggest the following: Like denopamine, the selective beta 1 full agonists, T-0509 and T-1583, at lower concentrations produce positive inotropic effects accompanied by only a small increase in cyclic AMP via stimulation of high-affinity beta 1-receptors. In higher concentrations, unlike denopamine, the two full agonists produce large increases in cyclic AMP loosely coupled to positive inotropy via stimulation of low-affinity beta 1-receptors.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Myocardial infarction induced by coronary venous thrombosis--an experimental study.

In a previous study, we proved experimentally that transmural infarction was produced in the area of the left anterior descending artery (LAD) by coronary sinus occlusion attributable to thrombus formation. In an attempt to produce infarction due to thrombus formation and to investigate the influence of thrombosis, the anterior interventricular vein (AIV) was occluded in this study. In each of 6 adult mongrel dogs, a balloon-tipped catheter was wedged in the AIV via the jugular vein. After the occlusion of blood flow by inflation of the balloon, thrombin (30-50 IU) was injected into the AIV to produce thrombi and the balloon was removed 60 min later. As a result, ischemic changes of ST and T in an ECG were clearly observed in all 6 dogs, and serum levels of myocardial enzymes supported the development of myocardial necrosis. Coronary arteriography performed 48 hours after the occlusion of the AIV showed normal findings in all 6 dogs, and residual thrombi in the AIV were observed in 5 dogs by coronary venography. In these 5 dogs, very local contraction band necrosis (CBN) was noted in the epicardium surrounding the AIV. These experimental findings indicate the following: 1) CBN can also be induced by coronary venous occlusion, 2) once the occlusive mechanism acts on the coronary venous system, the changes which are clinically similar to myocardial infarction can be induced regardless of its causes, 3) ischemic changes in myocardium can be localized in the epicardium irrespective of its causes. Therefore, these findings are considered to be important in the investigation of the clinical onset mechanism of myocardial infarction.

Animals↗
PubMed1990

Specific antagonism by glibenclamide of negative inotropic effects of potassium channel openers in canine atrial muscle.

The mode of antagonism by glibenclamide, a potassium channel blocker, of the negative inotropic effects of potassium channel openers, cromakalim, pinacidil and nicorandil, was investigated in canine atrial muscle. Glibenclamide shifted the concentration-negative inotropic effect curves for cromakalim, pinacidil and nicorandil to the right without affecting the basal force of contraction. Schild analysis yielded uniform pA2 values of 6.06-6.35 for glibenclamide against the three potassium channel openers. The force of contraction of atrial muscles previously reduced by cromakalim was also antagonized by increasing concentrations of glibenclamide. Glibenclamide affected neither the concentration-negative inotropic effect curves for carbachol, an opener of the muscarinic receptor-coupled potassium channel, nor those for nifedipine, a calcium channel blocker. From these results, it became evident that glibenclamide behaved as a pharmacological antagonist of cromakalim, pinacidil and nicorandil in cardiac inotropy. The antagonism seems to involve competition of glibenclamide and these potassium channel openers, presumably at the ATP-sensitive channel in canine right atrial muscles.

Animals↗
PubMed1990

[A rapid diagnosis for periodontitis based on enzymatic activity of periodontopathic bacteria. Correlation between enzymatic activity, clinical periodontal parameters, and subgingival level of microorganisms].

There have been various laboratory methods for the microbiological diagnosis of periodontal disease. However, there have been some disadvantages in these methods. In this study of the application of a chair-side test for microbiological diagnosis, the activity of peptidases in periodontal pockets of patients was examined by using the assay system SK-013. SK-013 consists of synthetic substrates and is capable of rapidly (in 15 min) evaluating the activity of specific peptidase from Treponema denticola and Bacteroides species. Using SK-013, we evaluate the correlation between the enzymatic activity, clinical periodontal parameters and subgingival level of microorganisms, including phase contrast microscopy. We calculated the sensitivity and efficacy of SK-013 as a diagnostic indicator in the presence of Spirochetes and in periodontitis. A positive correlation were demonstrated between enzymatic activity, clinical periodontal parameters, the numbers of total cell count, Spirochetes, and M & S ratio. SK-013 was highly sensitive and efficacious (sensitivity: 92%, efficacy: 96%). We concluded that the assay system SK-013 is a useful chair-side method for diagnosing periodontal disease.

Bacteroides↗
PubMed1990

[A rapid diagnosis for periodontitis based on the enzymatic activity of periodontopathic bacteria. The application of the SK-013 to the judgement on the effect of initial preparation].

The purpose of the present study was to examine the diagnostic value of the SK-013 (Sunstar, Osaka) in evaluating the effect of initial preparation. The SK-013 is a highly sensitive reagent to measure peptidase activity specifically produced by Bacteroides gingivalis. Bacteroides forsythus, and Treponema denticola. Thirty-six sites in 16 periodontitis patients were monitored in this study. The clinical status of each site was assessed using the clinical indices such as gingival index (GI), plaque index (PII), probing depth (PD), and bleeding on probing (BOP). The composition of subgingival microflora in samples was determined using phase contrast microscopy. Clinical, microbiological, and enzymatic examinations were made at five separate appointments, as follows: (1) at baseline prior to plaque control instruction; (2) 4 weeks following plaque control instruction; and (3) 2, 4, 8 weeks following scaling and root planing of periodontal sites. The results of these examinations were compared statistically. The correlation was positive between the total counts of bacteria including spirochetes and motile rods and the enzymatic activity identified using the SK-013. Also the enzymatic profile was highly correlated with microbiological findings other than clinical indices. These results show that the SK-013 is a clinically useful diagnostic method for assessing the effect of initial periodontal therapy.

Bacteroides↗
PubMed1990

Inhibitory effects of diltiazem, verapamil, nifedipine, and nicardipine on sympathetic tachycardia in decentralized hearts of anesthetized dogs.

Intravenous diltiazem (10-300 micrograms/kg), verapamil (10-300 micrograms/kg), nifedipine (1-100 micrograms/kg) and nicardipine (1-100 micrograms/kg) inhibited the tachycardia caused by cardiac sympathetic nerve stimulation (SNS, 0.5-4 Hz) in decentralized hearts of anesthetized dogs. The dose range of each drug required to inhibit the SNS-induced tachycardia was almost equivalent to that required to produce the increase in coronary blood flow and the decrease in blood pressure. Nifedipine and nicardipine were equi-active and about 10 times more potent than diltiazem and verapamil in inhibiting the SNS-induced tachycardia. They produced a slight but dose-dependent slowing of the resting heart rate. The negative chronotropic potency was approximately nicardipine, verapamil greater than nifedipine, diltiazem. Bay K 8644 (30 micrograms/kg) antagonized the inhibitory effects of diltiazem (100 micrograms/kg) and nifedipine (30 micrograms/kg) on the SNS-induced tachycardia. Tachycardia induced by intracoronary norepinephrine (0.03-0.3 micrograms) was suppressed by diltiazem (30-300 micrograms/kg) and nifedipine (10-100 micrograms/kg). The inhibitory effects of calcium entry blocking drugs on the sympathetic tachycardia appear to be explained by the interference of the beta-adrenoceptor-mediated increase in slow inward current in the sinoatrial (SA) node. It is also suggested that other mechanisms different from calcium entry blocking action contribute to the negative chronotropic response to these calcium entry blocking drugs.

Analysis of Variance↗
PubMed1990

[Comparison of effects of intravenous versus intramuscular famotidine on pH and volume of gastric juice].

Famotidine, an H2-antagonist, is frequently used for prevention of acid aspiration in surgical patients. Intravenous as well as intramuscular administration of famotidine has proved effective to reduce gastric acid secretion during anesthesia. However, the onset and duration of action of famotidine following intravenous administration has not been extensively investigated. In the present study on 89 patients undergoing elective surgery, the effects of famotidine 20 mg administered intravenously 5-30 min before endotracheal intubation on pH and volume of gastric contents aspirated 0, 1, 2, and 4 hrs after tracheal intubation and immediately after extubation through nasogastric tube were compared with the effects of the drug administered intramuscularly one hour before endotracheal intubation. Famotidine administered intramuscularly 5-14 min before endotracheal intubation produced inadequate suppression of gastric secretion after tracheal intubation. In contrast, intravenous famotidine given 15-30 min before tracheal intubation, as well as the intramuscular administration of famotidine as premedication, effectively decreased gastric fluid volume and increased gastric pH. Suppression of gastric secretion by intravenous and intramuscular famotidine continued for over 4 hours. Intravenous famotidine has a rapid onset and a long duration of depressant action on gastric secretion, thus reducing the risk of aspiration pneumonitis during and after general anesthesia.

Adult↗
PubMed1989

[3H]acetylcholine release and the change in cytosolic free calcium level induced by high K+ and ouabain in rat brain synaptosomes.

High K+ (50 mM) increased both [3H]acetylcholine ([3H]ACh) release and cytosolic free calcium level ([Ca2+]i) in rat brain synaptosomes in the presence of extracellular Ca2+. Ouabain (5 x 10(-8) to 5 x 10(-4) M) also caused a dose-dependent increase in [3H]ACh release, but not in [Ca2+]i, in the absence of Ca2+. The effects of high K+ and ouabain on [3H]ACh and/or [Ca2+]i, were inhibited by the intracellular Ca2+ antagonist TMB-8 (10(-4) M). These results suggest that unlike high K+, ouabain increases transmitter release from nerve endings through a mechanism which is independent of [Ca2+]i, but sensitive to TMB-8.

Acetylcholine↗