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H Mutoh

Publications and source records attributed to H Mutoh.

At least 73 records · Page 4Linked to original sources
PubMed1991

Oxygen metabolites stimulate mucous glycoprotein secretion from cultured rat gastric mucous cells.

The aims of this study were to investigate the interaction between oxygen radicals and mucus secretion from cultured rat gastric mucous cells, and to assess the role of prostaglandin production in the modulation of mucus secretion in vitro. Xanthine oxidase in the presence of hypoxanthine caused a dose-dependent increase in the presence of hypoxanthine caused a dose-dependent increase of mucus secretion, as assessed by release of [3H]glucosamine from prelabeled cells, whereas xanthine oxidase or hypoxanthine alone did not. Xanthine oxidase (10 mU/ml) increased release of [3H]glucosamine by 57 +/- 6% compared with control values (P less than 0.001). Catalase (3,000 U/ml) inhibited xanthine oxidase-induced mucus secretion by 69 +/- 9% (P less than 0.01), whereas superoxide dismutase did not. Pretreatment with deferoxamine, an inhibitor of hydroxyl radical generation through chelating ferric ion, diminished oxygen radical-induced mucus release to control values. Xanthine oxidase dose dependently stimulated prostaglandin E2 (PGE2) production, which was blocked by catalase but not by superoxide dismutase. However, oxygen radical stimulation of mucus secretion was not inhibited by the addition of indomethacin. Moreover, PGE2, exogenously administered, did not significantly accelerate mucus secretion. Stimulation of mucus secretion by oxygen radicals was not accompanied by increased 51Cr release or by leakage of intracellular lactate dehydrogenase. These results suggest that oxygen species, particularly hydroxyl radical, stimulate mucous glycoprotein secretion from cultured rat gastric mucous cells. However, it seems unlikely that prostaglandin production mediates the oxygen species-induced stimulation of mucus secretion.

Animals↗
PubMed1991

Antioxidant defenses of cultured gastric cells against oxygen metabolites: role of GSH redox cycle and endogenous catalase.

Gastric mucous epithelial cells may represent a first line of defense against reactive oxygen species that are generated within the gastric lumen. However, little is known about their defenses against oxidant species. This study examined the importance of the glutathione (GSH) redox cycle and of endogenous catalase as antioxidant defenses in cultured gastric mucous cells. Cultured rat gastric mucous cells were exposed to H2O2 generated by glucose oxidase acting on glucose or to nascent H2O2 for 5 h. Cytotoxicity was quantified by measuring 51Cr release from prelabeled cells. The effects of inhibition of the GSH redox cycle and of endogenous catalase were examined. Glucose oxidase caused a dose-dependent increase of 51Cr release. Similarly, nascent H2O2 damaged the cells dose dependently. Pretreatment with 1,3-bis(chloroethyl)-1-nitrourea (inhibitor of GSH reductase) dose dependently increased glucose oxidase-induced 51Cr release. Preincubation with buthionine sulfoximine (inhibitor of gamma-glutamyl-cysteine synthetase), which lowered intracellular GSH content, enhanced glucose oxidase-induced damage in a dose-dependent manner. Pretreatment with diethyl maleate, which covalently binds GSH as catalyzed by GSH transferase, also enhanced the sensitivity to lysis by glucose oxidase. However, inhibition of endogenous catalase activity by 3-amino-1,2,4-triazole did not significantly alter glucose oxidase- or nascent H2O2-induced 51Cr release. These results suggest that the GSH redox cycle rather than endogenous catalase plays a critical role in intracellular antioxidant defense in cultured gastric mucous cells.

Animals↗
PubMed1991

Tetraprenylacetone promotes healing process of ethanol-induced gastric damage in the rat.

Tetraprenylacetone (TPA: teprenon, geranylgeranylacetone) is a novel anti-ulcer agent developed in Japan. The aim of this study was to test whether TPA has the ability to promote the healing process of rat gastric mucosal injury induced by absolute ethanol (ET). Fasted rats received orally 5 ml/kg of absolute ET. Sixty minutes later, TPA (200 mg/kg) or saline (control) was administered intragastrically. Thereafter, the same dose of TPA or saline was given orally every 8 hours. To investigate the role of endogenous prostaglandins, indomethacin was given intraperitoneally every 8 hours. Twenty four or 48 hours after the first administration of TPA or saline, rats were sacrificed and the stomachs were removed. Administration of TPA significantly reduced lesion indices from 100 +/- 12.9% (control) to 57.0 +/- 12.8% (24 hours, P less than 0.05) and from 100 +/- 15.3% (control) to 17.6 +/- 3.4% (48 hours, P less than 0.01). Addition of indomethacin did not significantly affect this effect of TPA. Ultrastructural studies revealed that TPA stimulated regeneration of gastric mucosa damaged by ET after 24 and 48 hours. These results indicate that TPA has the ability to promote the healing process of gastric mucosal damage induced by absolute ET. It is, however, unlikely that endogenous prostaglandins are involved in this promotive effect of TPA on the healing process of gastric injury.

Animals↗
PubMed1991

The effect of cimetidine on adaptive cytoprotection by mild irritant dose of HCl in the rat gastric mucosa.

While cimetidine (CIM) is strikingly effective in inhibiting gastric acid secretion, its effect on the defensive mechanisms of the gastric mucosa has been controversial. The aims of the present study were to test if administration of CIM at an antisecretory dose is protective against acid-induced injury and to assess its effect on adaptive cytoprotection induced by non-necrotizing concentrations of HCl in rats. A dose of 100 mg/kg of CIM was administered once, or twice a day for 5 days intraperitoneally. To study the effect of CIM on HCl-induced damage, 0.6 N HCl was given orally one hour after the last administration of CIM. To study the effect of CIM on adaptive cytoprotection, 0.35 N HCl was given orally one hour after the last administration of CIM. Fifteen minutes later, 0.6 N HCl was given orally. Thirty minutes after the administration of 0.6 N HCl, the stomach was removed and ulcer indices were calculated. Pretreatment with CIM did not prevent 0.6 N HCl induced gastric damage. Prior administration of 0.35 N HCl significantly reduced ulcer indices caused by 0.6 N HCl. Short or long term treatment with CIM did not have significant effects on the reduction of ulcer indices. These results suggest that CIM at an antisecretory dose neither acts as a protective agent nor modulates the protective process of the gastric mucosa.

Adaptation, Physiological↗
PubMed1990

Leukotriene A4 hydrolase is a zinc-containing aminopeptidase.

A comparison of amino acid sequences revealed that leukotriene A4 (LTA4) hydrolase is homologous to various types of aminopeptidases. Consistently with the finding, the purified LTA4 hydrolases from both human and guinea pig sources contained equimolar zinc ion, as determined by atomic absorption spectrometry. The enzyme had a significant amount of aminopeptidase activity toward synthetic peptide substrates. Both LTA4 hydrolase and aminopeptidase activities were inhibited by o-phenanthroline, p-chloromercuribenzoic acid, and Leu-thiol with similar IC50 values. Co-purification as well as co-immunoprecipitation of both enzyme activities with an affinity-purified antibody against LTA4 hydrolase strongly suggest that the two enzyme activities reside in a single protein.

Aminopeptidases↗
PubMed1990

A monolayer culture of gastric mucous cells from adult rabbits.

A new method for the primary monolayer cultures of adult rabbit gastric mucous cells has been developed. Rabbit gastric mucosal cells were isolated with etylenediaminetetraacetic acid and collagenase. Cells were cultured in Coon's modified Ham's F-12 medium supplemented with 10% fetal bovine serum, 15mM HEPES buffer, antibiotics, and antimycotic. The cells reached confluency on days 3-4. Histochemically 92% of the cells contained PAS positive gramules (mucous cells), 3% of cells showed a strong reaction for succinic dehydrogenase activity (parietal cells), 2% of the cells showed positive granules by Bowie staining (chief cells), and G6PDH staining was positive in 5% of the cells (surface mucous cells). Fibroblasts were rarely seen until day 7 (less than 1%). Thus rabbit cultured gastric cells were considered to be mainly comosed of mucous neck cells. These cells produced prostaglandin (PG) E2 and PGI2. Quantitatively cultured cells synthesized 1.475 +/- 0.039 ng/mg protein/hour of PGE2 and 0.244 +/- 0.042 pg/mg protein/hour of PGI2. This relatively simple and convenient technique provides a useful model for the study of cellular functions of gastric mucosa.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

Protective role of intracellular glutathione against ethanol-induced damage in cultured rat gastric mucosal cells.

This study investigated whether intracellular glutathione is cytoprotective against ethanol-induced injury to cultured rat gastric mucosal cells in vitro. Secondly, it investigated whether reduced glutathione or oxidized glutathione is responsible for this cytoprotection. Cytolysis was quantified by measuring 51Cr release from prelabeled cells. Concentrations of ethanol greater than 12% caused cell damage and increased 51Cr release in a dose-dependent and time-related fashion. When a substrate for glutathione synthesis, N-acetyl-L-cysteine, was provided to cultured cells for 4 h before challenge with ethanol, cytolysis was significantly decreased corresponding with an increase in cellular glutathione content. Pretreatment with diethyl maleate, which depletes reduced glutathione without forming oxidized glutathione, potentiated ethanol-induced cell damage in a dose-dependent manner with the decrease of cellular glutathione content. The administration of tert-butyl hydroperoxide (which is specifically reduced by glutathione peroxidase to generate oxidized glutathione from reduced glutathione) or diamide (which nonenzymatically oxidizes reduced glutathione to oxidized glutathione) enhanced ethanol injury. We conclude that in cultured gastric mucosal cells, (a) intracellular glutathione maintains integrity of gastric mucosal cells against ethanol in vitro; and (b) reduced glutathione rather than oxidized glutathione is responsible for this cytoprotection. We postulate that the presence of reduced glutathione is essential to allow glutathione peroxidase to catalyze the ethanol-generated toxic oxygen radical, hydrogen peroxide.

Acetylcysteine↗
PubMed1990

Role of oxygen radicals in ethanol-induced damage to cultured gastric mucosal cells.

We have examined the role of oxygen radicals in ethanol-induced damage to cultured rat gastric mucosal cells. Cultured cells exposed to ethanol produced superoxide anion, as assessed by the reduction of cytochrome c, in a time-related fashion. The production of superoxide anion increased dose dependently as the concentration of ethanol increased. Cellular damage increased in a similar fashion to the production of superoxide anion. Both superoxide dismutase (SOD) and catalase diminished ethanol-induced injury dose dependently. SOD and catalase were able to maintain their enzymatic activities in the presence of 15% ethanol, respectively. Pretreatment with deferoxamine, an iron-chelating agent, decreased ethanol-induced injury dose dependently. Furthermore, dimethyl sulfoxide decreased ethanol-induced damage dose dependently. We conclude that cultured gastric mucosal cells exposed to ethanol generate oxygen radicals and that the production of oxygen radicals is closely linked with ethanol-induced damage to the cells. Hydroxyl radical, produced by the iron-catalyzed Haber-Weiss reaction, seems to be the main mediator of ethanol-induced damage to gastric mucosal cells in vitro.

Animals↗
PubMed1990

Ultrasound-guided percutaneous injection of ethanolamine oleate for hypersplenism. An experimental study in dogs.

In order to evaluate a possible therapy for hypersplenism, an experiment with animals was done. In nine dogs, 0.6 ml/kg body weight of 5% ethanolamine oleate was injected percutaneously into the spleen under ultrasound guidance. The injection was repeated three times at intervals of 1 week. Three dogs each were killed at 1, 4, and 8 weeks after the final injection. All dogs tolerated the procedure well and lived until they were killed. The platelet count and leukocyte count increased after the injections, and remained higher than the pretreatment level until death. This effect probably is due to depressed splenic function. The autopsy showed 40% of the spleen to be infarcted with complete destruction of the normal structure. No serious complications occurred. In addition, injection of ethanolamine oleate in six fully heparinized dogs showed that there was little risk of hemorrhage. Ultrasound-guided percutaneous injection of ethanolamine oleate might be a simple and effective therapy for hypersplenism.

Administration, Cutaneous↗
PubMed1989

Effect of adenosine and adenosine analogs on [14C]aminopyrine accumulation by rabbit parietal cells.

Adenosine receptors that modulate adenylate cyclase activity have been identified recently in a number of tissues. Adenosine A2 receptor is stimulatory to adenylate cyclase, whereas adenosine A1 receptor is inhibitory to adenylate cyclase. We investigated the effect of adenosine and its analogs on [14C]aminopyrine accumulation by rabbit parietal cells. Rabbit gastric mucosal cells were isolated by enzyme digestion. Parietal cells were enriched by nonlinear percoll gradients. [14C]Aminopyrine accumulation was used as an indicator of acid secretion. The effect of 2-chloroadenosine on histamine-stimulated [14C]aminopyrine accumulation was studied. The effects of N-ethylcarboxamideadenosine, 2-chloroadenosine, stable analogs of adenosine, and adenosine on [14C]aminopyrine accumulation were assessed. Cyclic AMP content of parietal cells was determined by radioimmunoassay. Histamine and carbachol, known secretagogues, stimulated [14C]aminopyrine accumulation. 2-Chloroadenosine did not suppress histamine-stimulated [14C]aminopyrine accumulation. 2-Chloroadenosine, N-ethylcarboxamideadenosine, and adenosine dose dependently increased [14C]aminopyrine accumulation. The order of potency was N-ethylcarboxamideadenosine greater than 2-chloroadenosine greater than adenosine. 8-Phenyltheophylline and theophylline, adenosine-receptor antagonists, or cimetidine did not have significant effects on the increase of AP uptake induced by 2-chloroadenosine. Coadministration of dipyridamole, and adenosine uptake inhibitor, augmented the effect of adenosine on [14C]aminopyrine accumulation. 2-Chloroadenosine, N-ethylcarboxamideadenosine, and adenosine each induced a significant increase in cellular cyclic AMP. We conclude that there may be adenosine A2 receptors on rabbit parietal cells which modulate gastric acid secretion.

2-Chloroadenosine↗
PubMed1989

[Establishment and characterization of a tumor marker producing cell line (JR-1) derived from a gastric scirrhous cancer].

Despite the importance of in vitro study of gastric cancer, the established cell lines derived from human gastric carcinoma are very few. We have recently established a new cell line derived from human gastric cancer which has the ability to produce several tumor markers. This cell line has been designated JR-1. The cancer cells were obtained from the cerebrospinal fluid of a 37 year-old female patient who had metastatic brain tumor of the poorly differentiated gastric adenocarcinoma. The cells were inoculated into the tissue culture flask containing Ham's F-12 medium supplemented with 10% fetal bovine serum, antibiotics. Within 24 hours, the cells attached to the surface of the flask and started to grow. The first subcultures were performed at 1 week, and subsequent subcultures have been done once a week. This cell line has been maintained for more than 15 months through 60 passages with a stable growth. Chromosome analysis of the cells was performed. The doubling time of the 20th passage was 72 hours. Under phase contrast microscopy, monolayered pavement-like cell arrangement was observed. PAS staining showed intracellular mucin granules. Transmission and scanning electron microscopy revealed spindle-shaped cells with numerous microvilli and fine projections as well as intracellular granules, indicating mucin. Tumor markers produced by this cell line were CEA, CA19-9, TPA and Procollagen III.

Adenocarcinoma, Scirrhous↗