We aimed to determine the status of iron in mediating oxidant-induced damage to cultured bovine aortic endothelial cells. Chromium-51-labeled cells were exposed to reaction mixtures of xanthine oxidase/hypoxanthine and glucose oxidase/glucose; these produce superoxide and hydrogen peroxide, or hydrogen peroxide, respectively. Xanthine oxidase caused a dose dependent increase of 51Cr release. Damage was prevented by allopurinol, oxypurinol, and extracellular catalase, but not by superoxide dismutase. Prevention of xanthine oxidase-induced damage by catalase was blocked by an inhibitor of catalase, aminotriazole. Glucose oxidase also caused a dose-dependent increase of 51Ci release. Glucose oxidase-induced injury, which was catalase-inhibitable, was not prevented by extracellular superoxide dismutase. Both addition of and pretreatment with deferoxamine (a chelator of Fe3+) prevented glucose oxidase-induced injury. The presence of phenanthroline (a chelator of divalent Fe2+) prevented glucose oxidase-induced 51Cr release, whereas pretreatment with the agent did not. Apotransferrin (a membrane impermeable iron binding protein) failed to influence damage. Neither deferoxamine nor phenanthroline influenced cellular antioxidant defenses, or inhibited lysis by non-oxidant toxic agents. Treatment with allopurinol and oxypurinol, which inhibited cellular xanthine oxidase, failed to prevent glucose oxidase injury. We conclude that (1) among the oxygen species extracellularly generated by xanthine oxidase/hypoxanthine, hydrogen peroxide induces damage via a reaction on cellular iron; (2) deferoxamine and phenanthroline protect cells by chelating Fe3+ and Fe2+, respectively; and (3) reduction of cellular stored iron (Fe3+) to Fe2+ may be prerequisite for mediation of oxidant-induced injury, but this occurs independently of extracellular superoxide or cellular xanthine oxidase-derived superoxide.

Allopurinol↗

PubMed1994

Growth regulation of rabbit gastric epithelial cells and protooncogene expression.

We recently developed a primary culture system for gastric epithelial cells from adult rabbits that allows the investigation of growth regulation at the cellular level. In this study, we demonstrated that epidermal growth factor (EGF), insulin, and dibutyryl adenosine 3',5'-cyclic monophosphate (dBcAMP) all stimulated cell proliferation. Insulin and dBcAMP potentiated the stimulation of cell proliferation by EGF, while transforming growth factor-beta 1 (TGF-beta 1) inhibited it. Expression of c-fos and c-myc was induced in response to the stimulation by these growth regulators, but the degree of expression did not necessarily correlate with the effects of these agents on cell proliferation. In conclusion, EGF, insulin, and dBcAMP were positive growth regulators, while TGF-beta 1 was a negative regulator in gastric epithelial cells. These growth modulators may exert their effects by distinct pathways from a standpoint of the expression of c-fos and c-myc.

Animals↗

PubMed1994

Role of iron and glutathione redox cycle in acetaminophen-induced cytotoxicity to cultured rat hepatocytes.

The aims of this study were to investigate the roles of iron as a catalyst in reactive oxygen metabolite-mediated cellular injury and of the endogenous antioxidant defenses against acetaminophen-induced cytotoxicity in cultured rat hepatocytes. Hepatocytes were isolated and cultured from either 3-methylcholanthrene-treated or untreated rats. Cytotoxicity was evaluated by measuring 51Cr and lactate dehydrogenase release. Acetaminophen caused dose-dependent cytotoxicity in 3-methylcholanthrene-treated, but not untreated, cells. There was a good correlation between 51Cr and lactate dehydrogenase release values. Pretreatment with both diethyl maleate, which covalently binds glutathione as catalyzed by glutathione-S-transferase, and bis(chloroethyl)-nitrosourea, an inhibitor of glutathione reductase, enhanced acetaminophen-induced cytotoxicity. Inhibition of endogenous catalase activity by pretreatment with aminotriazole did not affect acetaminophen-induced cellular damage. Addition of exogenous catalase failed to protect against acetaminophen-induced cytotoxicity. Preincubation with both deferoxamine, a ferric iron chelator, and phenanthroline, a ferrous iron chelator, diminished acetaminophen-induced cytotoxicity. These results indicate that iron is crucial in mediating acetaminophen-induced cytotoxicity and that the glutathione redox cycle, but not catalase, plays a critical role in the endogenous defenses against acetaminophen-induced cellular damage in cultured rat hepatocytes in vitro.

Acetaminophen↗

PubMed1994

Pseudomyxoma peritonei due to adenocarcinoma of the lung: case report.

A rare case of pseudomyxoma peritonei whose primary site was presumed to be the lung is reported. A 76-year-old woman was admitted to Hospital presenting with progressive abdominal distention. She had been admitted twice, 2 and 1 year previously for the evaluation of high plasma carcinoembryonic antigen (CEA) level, of 11.6 ng/ml. Chest computed tomography (CT) scan and chest X-ray film on the third admission revealed a nodular lesion in the left lower lung field, and transbronchial lung biopsy (TBLB) revealed mucus-producing tall columnar epithelial carcinoma. Paracentesis revealed gelatinous ascitic fluid. At laparotomy, appendix and ovary were normal, and there were many small cystic tumors on the peritoneal surface and omentum. The patient died 2 years later, after repeated episodes of dynamic ileus. The lung and abdominal tumors gradually increased in size during the 2-year period, but she developed no respiratory symptoms. Based on both the clinical and pathophysiological findings, the final diagnosis made was pseudomyxoma peritonei whose origin was a lung adenocarcinoma.

Adenocarcinoma↗

PubMed1994

Churg-Strauss syndrome (allergic granulomatous angiitis) with multiple perforating ulcers of the small intestine, multiple ulcers of the colon, and mononeuritis multiplex.

A case of Churg-Strauss syndrome with multiple perforations of the small intestine is described. A 31-year-old woman was admitted with a complaint of epigastric pain. She had a history of bronchial asthma. One week before admission, white blood cell count was 20,800/mm3 with 59% eosinophils. Neurological examination on admission disclosed mononeuritis multiplex with paresthesia in both the lower and upper extremities. At colonoscopy, there were scattered aphthous ulcers in the colon. Ophthalmological examination revealed allergic conjunctivitis. After admission, hypereosinophilia increased to as high as 36,000/mm3. Oral administration of prednisolone (60 mg/day) was begun. On the 3rd day of the treatment, the eosinophil count decreased dramatically, to 400/mm3, while severe abdominal pain developed. Since abdominal X-ray film revealed free air in the abdominal cavity, emergency laparotomy was performed and multiple intestinal ulcers with perforations were found. Partial ileectomy was performed. Pathological findings of the resected specimen were interpreted as a necrotizing angiitis with extravascular granuloma. Since the operation, the patient has been asymptomatic, except for neurological symptoms. Hypereosinophilia has decreased without treatment to counts averaging 270/mm3, within 3 months. On the basis of the clinical features and histopathological findings, a diagnosis of Churg-Strauss syndrome was established.

Adult↗

PubMed1994

Protection of cultured rat gastric cells against oxidant-induced damage by exogenous glutathione.

BACKGROUND/AIMS: Reduced glutathione (GSH) is an intracellular protectant against oxidants. The present study determined whether extracellular GSH protects against oxidant damage or whether an uptake system of GSH is present in cultured gastric cells. METHODS: Hydrogen peroxide was generated by glucose oxidase and glucose. Cytotoxicity was assessed by 51Cr release. Intracellular GSH was assayed by the method of Tietze. RESULTS: Pretreatment with extracellular GSH decreased H2O2-induced 51Cr release. Treatment with GSH enhanced cellular GSH content. Protection by pretreatment with GSH was prevented by buthionine sulfoximine (an inhibitor of gamma-glutamylcysteine synthetase). Enhancement of intracellular GSH was also prevented by buthionine sulfoximine. Acivicin (an inhibitor of gamma-glutamyl transpeptidase) prevented intracellular accumulation of GSH from extracellular GSH. Cysteine was effective in preventing damage and enhancing intracellular GSH content, whereas both glutamine and glycine were not. CONCLUSIONS: Extracellular GSH protects cultured gastric cells from H2O2 damage by accelerating intracellular GSH synthesis; this is mediated by membrane-bound gamma-glutamyl transpeptidase acting on extracellular GSH (which supplies these cells with cysteine) and then by intracellular gamma-glutamylcysteine synthetase.

Animals↗

PubMed1994

P2 purinergic receptor regulation of mucus glycoprotein secretion by rabbit gastric mucous cells in a primary culture.

BACKGROUND/AIMS: Physiological regulation of gastric mucus secretion has not been well studied. The present study investigated the effects of adenosine 5'-triphosphate (ATP), a P2 purinergic receptor agonist, and its analogues on gastric mucus secretion using gastric mucous cells in a primary culture. METHODS: A monolayer culture of gastric mucous cells from adult rabbits were prepared after enzyme digestion. Mucus secretion was estimated from the release of [3H]glucosamine from prelabeled cells. Intracellular calcium concentration ([Ca2+]i) was monitored by a Ca(2+)-sensitive probe, indo-1. Prostaglandin E2 (PGE2) in the media was measured by an enzyme-linked immunoassay. RESULTS: ATP significantly stimulated mucus secretion by these cells at nontoxic doses in a dose-dependent fashion. The order of potency of ATP analogues stimulating mucus secretion was alpha beta-methylene ATP > ATP > 2-methylthio ATP, whereas adenosine, a P1 purinergic receptor agonist, had no effect. ATP also induced an elevation of [Ca2+]i in a dose-dependent fashion. The efficacy of ATP analogues to increase [Ca2+]i showed a similar potency to their actions on mucus secretion. ATP increased PGE2 at relatively higher concentrations, whereas indomethacin did not block ATP-induced increase of mucus secretion. CONCLUSIONS: These results suggest that ATP stimulates mucus secretion by gastric mucous cells through P2 purinergic receptors; this appears to be mediated by intracellular calcium not by endogenous PGE2.

Adenosine↗

PubMed1994

Stimulation of prostaglandin E2 release from cultured rabbit gastric cells by sodium deoxycholate.

Although bile salts are irritants in the gastric mucosa, their effects on prostaglandin (PG) release have not been well studied. We investigated the effects of bile salts on PGE2 release and the possible mechanisms involved. Cultured rabbit gastric mucous epithelial cells were studied. PGE2 was measured by radioimmunoassay. Intracellular free Ca2+ concentration was measured with Ca2+ fluorescent dye indo-1 AM. Dihydroxy bile salts, such as chenodeoxycholate and deoxycholate (DC), dose-dependently increased PGE2 release, while non-dihydroxy bile salts did not. Since agents involved in the cellular signal transduction system have been reported to play important roles in PG release, the possible involvement of Ca2+, calmodulin, and protein kinase C (PKC) in DC-induced PGE2 release was studied. Deprivation of Ca2+ from the medium blocked DC-induced PGE2 release. Lanthanum (La3+), which displaced surface-bound Ca2+, suppressed DC-induced PGE2. However, BAPTA (a chelator of intracellular Ca2+) did not decrease it. Neither calmodulin inhibitors nor PKC inhibitors altered DC-induced PGE2 release. DC increased intracellular free Ca2+ concentrations. This effect was blocked by deprivation of Ca2+ from the medium. Quinacrine (a phospholipase A2 inhibitor) blocked DC-induced PGE2 release. These results suggest that in cultured rabbit gastric cells, deoxycholate stimulates PGE2 release mainly through the influx of extracellular Ca2+.

Animals↗

PubMed1994

Protective role of intracellular superoxide dismutase against extracellular oxidants in cultured rat gastric cells.

We examined the role of intracellular superoxide dismutase (SOD) as an antioxidant by studying the effect of diethyldithiocarbamate (DDC) on extracellular H2O2-induced damage in cultured rat gastric mucosal cells. 51Cr-labeled monolayers from rat stomachs were exposed to glucose oxidase-generated H2O2 or reagent H2O2, which both caused a dose-dependent increase in 51Cr release. DDC dose-dependently enhanced 51Cr release by hydrogen peroxide, corresponding with inhibition of endogenous SOD activity. This inhibition was not associated either with modulation of other antioxidant defenses, or with potentiation of injury by nonoxidant toxic agents. Enhanced hydrogen peroxide damage by DDC was significantly prevented by chelating cellular iron with deferoxamine or phenanthroline. Inhibition of cellular xanthine oxidase (possible source of superoxide production) by oxypurinol neither prevented lysis by hydrogen peroxide nor diminished DDC-induced sensitization to H2O2. We conclude that (a) extracellular H2O2 induces dose dependent damage to cultured gastric mucosal cells; (b) intracellular SOD plays an important role in preventing H2O2 damage; (c) generation of superoxide seems to occur intracellularly after exposure to H2O2, but independent of cellular xanthine oxidase; and (d) cellular iron mediates the damage by catalyzing the production of more reactive species from superoxide and H2O2, the process which causes ultimate cell injury.

Animals↗

PubMed1994

Role of protective drugs in the prevention of ulcer relapse.

The efficacy of gastric acid suppressive drugs, such as histamine H2-receptor antagonists and H+K+ ATPase inhibitors, in the management of peptic ulcer diseases has been well established. They accelerate the healing of peptic ulcers, and maintenance therapy with these drugs prevents ulcer relapse. However, they do not modulate the natural course of peptic ulcer. Sucralfate, a protective drug, has been shown to be equally effective in ulcer healing and the prevention of ulcer relapse. Some reports suggest that the relapse rate of ulcers treated successfully with sucralfate is less than that seen with histamine H2-receptor antagonists. Sucralfate has a true cytoprotective effect against agents noxious to gastric epithelial cells in monolayer culture. This action might be associated with its therapeutic efficacy in the treatment and prevention of ulcer diseases. The role played by other protective drugs in the management of ulcer diseases is less clear and requires further studies.

Anti-Ulcer Agents↗

PubMed1994

Bile salts stimulate mucous glycoprotein secretion from cultured rabbit gastric mucosal cells.

Resistance of gastric mucosa to damage is increased after exposure to mild irritants such as bile salts (adaptive cytoprotection). Mucus secretion also contributes to gastric cytoprotection. We investigated whether bile salts stimulate mucous glycoprotein secretion from cultured rabbit gastric mucosal cells. Because prostaglandins (PGs) stimulate mucus secretion, we assessed the role of endogenous PG release in bile salt-stimulated mucus secretion. Because Ca2+ plays a role in PGE2 release, the role of extracellular Ca2+ on PGE2 release and mucus secretion by bile salts was also studied. Rabbit gastric mucosal cells were prepared with collagenase and ethyl-enediaminetetraacetic acid. These cells were cultured as described previously. Cytotoxicity of bile salts was quantified by measuring chromium 51 release from prelabeled cells. PGE2 was measured by radioimmunoassay. Mucous glycoprotein secretion was assessed by tritiated glucosamine release assay. Deoxycholate (DC) and glycodeoxycholate (GDC) stimulated tritiated glucosamine release in doses that were not cytotoxic to the cultured cells. DC stimulated PGE2 release that was blocked by deprivation of extracellular Ca2+. GDC did not stimulate PGE2 release. Neither DC-stimulated nor GDC-stimulated mucus secretion was affected by indomethacin. Deprivation of extracellular Ca2+ did not affect DC-stimulated or GDC-stimulated mucus secretion. Bile salts stimulated mucous glycoprotein secretion from cultured rabbit gastric mucosal cells. This effect occurred independently of changes in endogenous PGE2 or extracellular Ca2+ concentrations.

Animals↗

PubMed1994

[A case of biliary cystadenocarcinoma communicating with the bile ducts].

Explore the source record for details and available documents.

Bile Ducts↗

PubMed1993

Quantitation of HTLV-I provirus among seropositive blood donors: relation with antibody profile using synthetic peptides.

To study the pathophysiological state of HTLV-I carriers and the quantitative aspect of the risk of HTLV-I infection, we measured the absolute amounts of HTLV-I provirus in 39 seropositive blood donors. The amount of provirus varied from less than one to more than 10(4) molecules per 10(5) peripheral-blood mononuclear cells (PBMC). The average amount of HTLV-I provirus among seropositive blood donors was estimated as 3.7 x 10(3) molecules per 10(5) PBMC. The titer of the antibody against only the synthetic peptide (aa 100 to 130) of the gag p19 region of the HTLV-I provirus showed a weak but significant correlation with the amount of the provirus.

Adult↗