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Biomedical subjects

A Terano

Publications and source records attributed to A Terano.

At least 127 records · Page 7Linked to original sources
PubMed1993

Two different promoters direct expression of two distinct forms of mRNAs of human platelet-activating factor receptor.

The human platelet-activating factor (PAF) receptor gene exists as a single copy on chromosome 1. We identified two 5'-noncoding exons, each of which has distinct transcriptional initiation sites. These exons are alternatively spliced to a common splice acceptor site on a third exon that contains the total open reading frame to yield two different species of functional mRNA (Transcript 1 and 2). Transcript 1 has consensus sequences for transcription factor NF-kappa B and Sp-1, and the Initiator (Inr) sequence homologous to the murine terminal deoxynucleotidyltransferase gene. Transcript 2 also contains consensus sequences for transcription factor AP-1, AP-2, and Sp-1. Transcripts 1 and 2 were both detected in heart, lung, spleen, and kidney, whereas only Transcript 1 was found in peripheral leukocytes, a differentiated human eosinophilic cell line (EoL-1 cells), and brain. Existence of distinct promoters was thus suggested to play a role in the regulatory control of PAF receptor gene expression in different human tissues and cells.

Alternative Splicing↗
PubMed1993

Hepatocyte growth factor induces mitogenic reaction to the rabbit gastric epithelial cells in primary culture.

Hepatocyte Growth Factor (HGF) was originally identified as hepatotrophic factor for liver regeneration. More recently, HGF was revealed to stimulate proliferation of various epithelial cells. At present study, we have investigated the mitogenic effect of HGF on gastric epithelial cells in the primary culture system. HGF remarkably stimulated proliferation of these cells dose dependently and synergistically with EGF and insulin. Mitogenic action of HGF might be mediated not by intracellular Ca2+ but by tyrosine kinase pathway. Conditioned medium of cultured fibroblast-like cells showed proliferative effects on cultured gastric epithelial cells in a similar way as exogenous HGF. These results suggest that HGF might be involved in the repair process of gastric mucosa.

Animals↗
PubMed1993

Roles of Ca2+ and protein kinase C in regulation of prostaglandin E2 release by cultured rabbit gastric epithelial cells.

Prostaglandin (PG) has been reported to be one of the important protective factors in the gastric mucosa. However the mechanism of the regulation of endogenous PG production has not been well studied. We investigated the possible roles of Ca2+, cAMP, and protein kinase C (PKC) in the regulation of PGE2 release from cultured rabbit gastric mucosal cells. PGE2 was measured by radioimmunoassay. A23187 (Ca2+ ionophore) at 2 x 10(-6) M significantly increased PGE2 release. Deprivation of Ca2+ from the medium blocked the A23187-induced increase of PGE2. TMB-8 (a putative inhibitor of Ca2+ release from intracellular stores) did not have any significant effects on the increase of PGE2-induced by A23187. Thus, A23187 increased PGE2 through the influx of extracellular Ca2+. W7 or compound 48/80 (calmodulin inhibitors) did not alter the response of PGE2 caused by A23187. Exogenous administration of cAMP, forskolin (an activator of adenylate cyclase), or 2-chloroadenosine (a possible activator of adenylate cyclase through adenosine A2 receptor) had neither significant effects on PGE2 release nor an effect on A23187-induced increase of PGE2 release. 12-O-tetradecanoylphorbol 13-acetate (TPA, an activator of PKC) significantly stimulated PGE2 release in a dose-dependent fashion, whereas another phorbol ester with no biological activity did not. A23187 at 0.8 x 10(-6) M, but not cAMP, potentiated the TPA-induced increase of PGE2. Mepacrine (a phospholipase A2 inhibitor) reduced the A23187- and TPA-induced increase of PGE2. These results suggest that Ca2+ and protein kinase C may play important roles in the regulation of PGE2 release by cultured rabbit gastric cells.

2-Chloroadenosine↗
PubMed1993

Antioxidant protection against oxidant-induced damage in cultured gastric mucosal cells.

Gastric epithelium is exposed not only to oxidants generated within the lumen, but also to those produced by ischemia/reperfusion. This study examined the mechanism(s) of oxidant-induced injury to cultured rat gastric mucosal cells, and characterized the antioxidant profile of these cells. Hydrogen peroxide (H2O2), generated by glucose oxidase, damaged cells dose-dependently, as assessed by increased leakage of labeled 51Cr. Glucose oxidase-induced damage was prevented by exogenous catalase (but not by exogenous superoxide dismutase). Chelation of cellular iron with desferrioxamine or phenanthroline specifically protected cells against H2O2, whereas binding of extracellular iron with apotransferrin failed to. Disruption of the glutathione redox cycle at three independent sites rendered cells less resistant to H2O2, whereas inhibition of cellular catalase did not result in sensitization of cells to H2O2. In conclusion, (1) oxidant injury induced by extracellular H2O2 is mediated by intracellular iron; (2) extracellular superoxide is not involved in the damaging process; and (3) the glutathione redox cycle plays a principal role in detoxifying H2O2 as a cellular antioxidant in cultured gastric mucosal cells.

Animals↗
PubMed1993

Role of iron and superoxide in mediating hydrogen peroxide injury to cultured rat gastric cells.

BACKGROUND: Gastric epithelium is exposed to toxic, reactive oxygen species generated within the lumen. The present study examined the role of cellular iron and superoxide (O2-) in mediating hydrogen peroxide (H2O2)-induced damage to cultured gastric mucosal cells. METHODS: H2O2 was generated by glucose oxidase acting on b-D(+)glucose. Cytotoxicity was assessed by 51Cr release from prelabeled cells. RESULTS: Deferoxamine (a chelator of Fe3+) prevented injury induced by H2O2, whether present before or during H2O2 production. In contrast, whereas the presence of phenanthroline (a chelator of Fe2+) during the cytotoxicity assay prevented damage, prior treatment with the agent did not; this suggested that cellular Fe3+ reduced to Fe2+ upon exposure to H2O2 is responsible for damage. Neither extracellular superoxide dismutase nor inhibitors of xanthine oxidase (a possible source of cellular O2- production) protected against H2O2. Further, protection by iron chelators was not associated with modulation of endogenous antioxidants. CONCLUSIONS: Deferoxamine and phenanthroline protect cells from H2O2 by chelating stored iron (Fe3+) or reduced iron (Fe2+), respectively. Reduction of cellular Fe3+ appears to be a prerequisite for mediation of damage, but this reduction is independent of extracellular O2- or cellular xanthine oxidase-derived O2-.

Allopurinol↗
PubMed1993

Primary colonic epithelial cell culture of the rabbit producing prostaglandins.

We have established primary colonic epithelial cell culture from adult rabbits and examined effects of anti-inflammatory drugs on prostaglandin (PG) E2 production. Colonic epithelium of adult rabbits was scraped and minced into small pieces. They were incubated for isolation in Hanks' balanced salt solution with 0.35% collagenase and Earle's solution with 1 mM EDTA. Isolated cells were cultured in Coon's modified Ham's F-12 medium with 10% fetal bovine serum and antibiotics on collagen coated cell wells. The medium was refed twice a week. The production of PGs was assessed by high pressure liquid chromatography (HPLC). PGE2 and PGF2 alpha were measured by radioimmunoassay. Within 24 hours after inoculation, the cell clumps attached to the surface of the wells and cells began to spread out and grow. Monolayer cultures became confluent in 4 days. Phase contrast microscopy showed that these cells consisted of a homogeneous population of epithelial cells with large oval nuclei, polyhedral shape, and organized sheet-like growth pattern. HPLC profile showed synthesis of 6-keto-PGF1 alpha, thromboxane B2, PGF2 alpha, PGE2, and PGD2 by cultured cells. Quantitatively, 117 +/- 7 ng/mg-protein/hour PGE2 and 7.4 +/- 0.7 ng/mg-protein/hour PGF2 alpha were produced. While hydrocortisone (10(-4) - 10(-2) M) did not show a significant effect on PGE2 production, indomethacin (10(-8) - 10(-6) M), and 5-aminosalicylic acid (2X10(-4)-5X10(-3) M) inhibited PGE2 production. We have established relatively convenient procedure for primary culture of colonic epithelial cells from adult rabbits. Different actions of anti-inflammatory drugs on PGE2 synthesis suggest that these cultured cells might be a good tool for the various cellular functional studies of normal colonic epithelial cells.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Activation of Ca(2+)-dependent K+ current by acetylcholine and histamine in a human gastric epithelial cell line.

The effects of acetylcholine (ACh) and histamine (His) on the membrane potential and current were examined in JR-1 cells, a mucin-producing epithelial cell line derived from human gastric signet ring cell carcinoma. The tight-seal, whole cell clamp technique was used. The resting membrane potential, the input resistance, and the capacitance of the cells were approximately -12 mV, 1.4 G ohms, and 50 pF, respectively. Under the voltage-clamp condition, no voltage-dependent currents were evoked. ACh or His added to the bathing solution hyperpolarized the membrane by activating a time- and voltage-independent K+ current. The ACh-induced hyperpolarization and K+ current persisted, while the His response desensitized quickly (< 1 min). These effects of ACh and His were mediated predominantly by m3-muscarinic and H1-His receptors, respectively. The K+ current induced by ACh and His was inhibited by charybdotoxin, suggesting that it is a Ca(2+)-activated K+ channel current (IK.Ca). The measurement of intracellular Ca2+ ([Ca2+]i) using Indo-1 revealed that both agents increased [Ca2+]i with similar time courses as they increased IK.Ca. When EGTA in the pipette solution was increased from 0.15 to 10 mM, the induction of IK.Ca by ACh and His was abolished. Thus, both ACh and His activate IK.Ca by increasing [Ca2+]i in JR-1 cells. In the Ca(2+)-free bathing solution (0.15 mM EGTA in the pipette), ACh evoked IK.Ca transiently. Addition of Ca2+ (1.8 mM) to the bath immediately restored the sustained IK.Ca. These results suggest that the ACh response is due to at least two different mechanisms; i.e., the Ca2+ release-related initial transient activation and the Ca2+ influx-related sustained activation of IK.Ca. Probably because of desensitization, the Ca2+ influx-related component of the His response could not be identified. Intracellularly applied inositol 1,4,5-trisphosphate (IP3), with and without inositol 1,3,4,5-tetrakisphosphate (IP4), mimicked the ACh response. IP4 alone did not affect the membrane current. Under the steady effect of IP3 or IP3 plus IP4, neither ACh nor His further evoked IK.Ca. Intracellular application of heparin or of the monoclonal antibody against the IP3 receptor, mAb18A10, inhibited the ACh and His responses in a concentration-dependent fashion. Neomycin, a phospholipase C (PLC) inhibitor, also inhibited the agonist-induced response in a concentration-dependent fashion. Although neither pertussis toxin (PTX) nor N-ethylmaleimide affected the ACh or His activation of IK,Ca, GDP beta S attenuated and GTP gamma S enhanced the agonist response.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗
PubMed1993

Antiulcer drugs and gastric prostaglandin E2: an in vitro study.

Prostaglandin (PG) has been reported to be an important protective and acid-suppressive factor in the gastric mucosa. Although the mechanisms of some antiulcer drugs are attributed to their stimulatory effects on endogenous prostaglandins, an understanding of these actions has not been established. In the present study we investigated the effects of antiulcer drugs on PGE2 using cultured gastric mucosal cells. Rabbit gastric mucosal cells were cultured after isolation with collagenase and ethylenediaminetetraacetic acid. PGE2 was measured by enzyme-linked immunoassay. Histamine H2-blockers (cimetidine, ranitidine, famotidine), omeprazole, and sucralfate did not modulate the media content of PGE2, whereas sofalcone dose- and time-dependently increased it. Sofalcone-induced increase of PGE2 was dose-dependently prevented by indomethacin. Sofalcone did not affect intracellular Ca2+ as assessed by the calcium-sensitive probe indo-1. Deprivation of Ca2+ in the media did not modulate the action of sofalcone. Sofalcone significantly suppressed 15-OH-PG dehydrogenase. These results suggest that among the various antiulcer drugs only sofalcone increases PGE2, which may be a factor in its therapeutic effect against peptic ulcer diseases.

Animals↗
PubMed1993

Percutaneous ethanol injection therapy for hepatocellular carcinoma: results in 146 patients.

OBJECTIVE: Sonographically guided percutaneous ethanol injection therapy has been used widely in the treatment of hepatocellular carcinoma. However, few reports have been published on the results of this treatment in large numbers of patients. Accordingly, we describe our experience with 146 patients who had this treatment. The study is an update of our previous reports on this subject. SUBJECTS AND METHODS: We used ethanol injection, with or without transcatheter arterial embolization, 1048 times in 146 patients who had 242 lesions of hepatocellular carcinoma. In 98 patients, ethanol injection was used to attempt a cure of the disease. In the remaining 48 patients, ethanol injection was used palliatively only to reduce the tumor burden. In most cases, 2-8 ml of absolute ethanol was injected in one treatment session. Patients were given the injections two or three times each week until ethanol was injected throughout the lesion. When tumors were greater than 2 cm in diameter, ethanol was injected into the edges of the lesion. RESULTS: Histopathologic examination after treatment in 21 cases showed that the lesion was completely necrotic in 15 cases, 90% necrotic in five cases, and 70% necrotic in the remaining case. Follow-up angiography performed in 69 cases showed no contrast stains in the treated tumors in 60 cases. Elevated serum levels of alpha-fetoprotein decreased in 39 of 43 cases. The 1-, 2-, 3-, 4-, and 5-year survival rates of all 146 patients were 79%, 64%, 46%, 38%, and 38%, respectively. Among 98 patients in whom ethanol injection was used as a potentially curative therapy, these rates were 85%, 70%, 62%, 52%, and 52%, respectively. After ethanol injection, the cancer recurred frequently; the 1-, 2-, 3-, 4-, and 5-year recurrence rates in the potentially curative group were 26%, 38%, 51%, 60%, and 60%, respectively. However, 84% of recurrences were new lesions in different portions of the liver; recurrence of lesions treated by ethanol injection was rare. Major complications of the treatment were peritoneal bleeding in two cases and pleural effusion in one case. CONCLUSION: Histopathologic examination, angiography, and serum levels of alpha-fetoprotein showed that percutaneous ethanol injection is a valuable treatment of hepatocellular carcinoma. The therapy increased the long-term survival of patients who have this disease.

Carcinoma, Hepatocellular↗
PubMed1993

Role for mucous glycoprotein in protecting cultured rat gastric mucosal cells against toxic oxygen metabolites.

The gastric epithelium is exposed to oxygen radicals that are generated within the lumen. Much interest has been focused on the role of mucus in maintaining integrity of the gastric mucosa against oxidants, because gastric mucus may act as a scavenger of oxygen radicals. The aim of this study was to assess the role of mucous glycoprotein in protecting cultured gastric epithelial cells against oxygen radicals. Monolayer cultures of rat gastric mucus-producing cells were studied. Oxygen radicals were generated by hypoxanthine and xanthine oxidase. Cytotoxicity was quantified by measuring chromium 51 release form prelabeled cells. Rate of mucous synthesis was estimated by incorporation of tritiated glucosamine into the cells. The effects of tetraprenyl acetone (a stimulant of mucus production) and N-acetyl-L-cysteine (a mucolytic agent) on oxygen radical-induced damage were determined. Preincubation with tetrapenyl acetone, while stimulating mucous glycoprotein by the cultured cells, caused a dose-dependent reduction of hypoxanthine-xanthine oxidase-induced 51Cr release, reaching maximum protection of the damage by 31% to 50%. In contrast, pretreatment with N-acetyl-L-cysteine potentiated oxygen radical-induced 51Cr release dose dependently. The protective effect of tetraprenyl acetone was significantly abolished by N-acetyl-L-cysteine. Neither tetraprenyl acetone nor N-acetyl-L-cysteine alone under the conditions of this study affected the cellular content of glutathione, which modulates oxygen radical injury to these cells. These results suggest that mucous glycoprotein partially but significantly protects cultured gastric epithelial cells against extracellularly generated oxygen radicals. It seems likely, therefore, that gastric mucus is involved in antioxidant defenses in these cells.

Acetylcysteine↗
PubMed1992

Role of cellular superoxide dismutase against reactive oxygen metabolite injury in cultured bovine aortic endothelial cells.

We examined the protective effect of cellular superoxide dismutase against extracellular hydrogen peroxide in cultured bovine aortic endothelial cells. 51Cr-labeled cells were exposed to hydrogen peroxide generated by glucose oxidase/glucose. Glucose oxidase caused a dose-dependent increase of 51Cr release. Pretreatment with diethyldithiocarbamate enhanced injury induced by glucose oxidase, corresponding with the degree of inhibition of endogenous superoxide dismutase activity. Inhibition of cellular superoxide dismutase by diethyldithiocarbamate was not associated either with alteration of other antioxidant defenses or with potentiation of nonoxidant injury. Enhanced glucose oxidase damage by diethyldithiocarbamate was prevented by chelating cellular iron. Inhibition of cellular xanthine oxidase neither prevented lysis by hydrogen peroxide nor diminished enhanced susceptibility by diethyldithiocarbamate. These results suggest that, in cultured endothelial cells: 1) cellular superoxide is involved in mediating hydrogen peroxide-induced damage; 2) superoxide, which would be generated upon exposure to excess hydrogen peroxide independently of cellular xanthine oxidase, promotes the Haber-Weiss reaction by initiating reduction of stored iron (Fe3+) to Fe2+; 3) cellular iron catalyzes the production of a more toxic species from these two oxygen metabolites; 4) cellular superoxide dismutase plays a critical role in preventing hydrogen peroxide damage by scavenging superoxide and consequently by inhibiting the generation of the toxic species.

Allopurinol↗
PubMed1992

Role of cellular superoxide dismutase against reactive oxygen metabolite-induced cell damage in cultured rat hepatocytes.

Reactive oxygen metabolites have been reported to be important in the pathogenesis of ischemia/reperfusion-induced and alcohol- and drug-induced liver injuries. We investigated the role of superoxide dismutase, cellular and extracellular, in preventing reactive oxygen metabolite-induced cytotoxicity in cultured rate hepatocytes. Cells were exposed to reactive oxygen metabolites enzymatically generated by hypoxanthine-xanthine oxidase. Cytotoxicity was quantified by measuring 51Cr release from prelabeled cells and lactate dehydrogenase release. Reactive oxygen metabolites caused dose-dependent cytotoxicity. Good correlation was found between the values for 51Cr and lactate dehydrogenase release. Reactive oxygen metabolite-induced cell damage was reduced by catalase but not by superoxide dismutase. Cellular superoxide dismutase and catalase activities were not increased after incubation with exogenous superoxide dismutase and catalase for up to 5 hr. Pretreatment with diethyldithiocarbamate inhibited cellular superoxide dismutase activity without inhibiting other antioxidants such as catalase, glutathione, glutathione reductase and glutathione peroxidase and sensitized cells to reactive oxygen metabolite-induced cytotoxicity. We conclude that hydrogen peroxide is an important mediator in hypoxanthine-xanthine oxidase-induced cell damage and that superoxide dismutase plays a critical role in cellular antioxidant defenses against hypoxanthine-xanthine oxidase-induced cytotoxicity in cultured rat hepatocytes in vitro.

Analysis of Variance↗
PubMed1992

The effects of acid secretagogues on protective agents of gastric cells from adult rabbits in vitro.

Endogenous prostaglandin and mucus have been recognized as important protective factors in the gastric mucosa. However, the regulatory mechanisms of these agents have not been well studied. The aim of the present study was to investigate the effects of acid secretagogues on cyclic adenosine monophosphate (cAMP) formation, prostaglandin E2 (PGE2) production, and mucus secretion by isolated parietal cells and culture mucous cells from adult rabbits. Rabbit parietal cells were enriched by nonlinear Percoll gradients after the isolation of rabbit gastric mucosal cells with collagenase and ethylenediaminetetraacetic acid (EDTA). Rabbit gastric mucous cells were cultured in 10% fetal bovine serum added to Ham's F12 medium. As gastric acid secretagogues, histamine, carbachol, gastrin, and 2-chloroadenosine were tested. To evaluate the effects of the second messengers of cellular signal transduction on protective agents, A23187, which is a calcium ionophore, and cAMP were used. PGE2 and cAMP were measured by radioimmunoassay. The release of [3H]glucosamine from prelabeled cells was used as an indicator of mucus secretion. Histamine, carbachol, gastrin, and 2-chloroadenosine did not modulate PGE2 production by parietal cells. Exogenously administered cAMP did not affect PGE2 production by parietal cells, whereas it was significantly increased by A23187. 2-Chloroadenosine but not histamine or carbachol significantly increased cAMP formation by mucous cells. Histamine, carbachol, and gastrin did not have significant effects on PGE2 production by mucous cells. 2-Chloroadenosine, which increased cAMP, also did not modulate PGE2 production. A23187 but not cAMP increased PGE2 production by mucous cells. None of the acid secretagogues used in the present study modulated mucus secretion. A23187 but not cAMP significantly increased mucus secretion by cultured mucus cells.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Chloroadenosine↗
PubMed1992

A simple and reliable method for the detection and quantitation of the human T-cell leukemia virus type-I provirus in peripheral blood mononuclear cells of seropositive blood donors.

Human T-cell leukemia virus type I (HTLV-I) antibody detection has been widely used to screen HTLV-I carriers. Sometimes, however, it gives false positive or negative results. A demonstration of the HTLV-I provirus from patients' peripheral blood mononuclear cells (PBMC) should, therefore, give the crucial evidence for them being HTLV-I carriers. We established a simple and reliable method using the polymerase chain reaction (PCR) to detect one molecule of HTLV-I provirus in 100 x 10(3) PBMC, during which internal control primers for the human beta-globin gene were also employed in the same reaction tube to check the success of the amplification reaction. We can thus easily avoid any false negative judgement and quantitate the HTLV-I provirus in PBMC simply by diluting the sample before PCR. One ml blood was enough for ten or more determinations by PCR. Analysis of seropositive blood from donors demonstrated a wide range for the number of HTLV-I provirus in PBMC. The method could conveniently be used for quantitating HTLV-I proviruses and following up HTLV-I carriers to study the pathophysiology and mode of HTLV-I transmission.

Base Sequence↗
PubMed1992

[Acid base balance in the digestive system].

The mechanisms of acid base balance in digestive organs, including stomach, intestine as well as liver, have been described in the present paper. The stomach secrets large amount of acid as well as sodium bicarbonate, so that hydrogen ion would be lost in the severe vomiting state such as pyloric stenosis, resulting in metabolic alkalosis and hypokalemia. In the diarrheal condition, sodium bicarbonate would be lost in large amount, causing metabolic acidosis and hypokalemia. Hepatic failure induces the respiratory alkalosis of which mechanisms have not been clarified yet. In any case, urgent correction of acid base imbalnce would be crucial. It is, however, obscure to date how the systemic acid base imbalnce affects the function of the digestive system. This issue would be promising field in the investigation of digestive diseases.

Acid-Base Imbalance↗
PubMed1991

Percutaneous ethanol injection therapy for hepatocellular carcinoma. A histopathologic study.

Histopathologic examination was done on 18 cases after percutaneous ethanol injection therapy (PEIT) for hepatocellular carcinoma. In eight cases, the lesion was treated by PEIT alone; in the other ten cases, PEIT was combined with transcatheter arterial embolization. The lesion was completely necrotic in 13 cases, 90% necrotic in four cases, and 70% necrotic in the rest. In addition, PEIT seemed to be effective against intercapsular, extracapsular, and vascular invasions. In the four cases of incomplete necrosis, the viable cancer tissue remained in small tumor nodules around the main tumor, in portions isolated by septa, or along the edge of the lesion. Therefore, ethanol should be injected not only into the center of the lesion, but also into sites close to its edge. Ethanol did not damage noncancerous liver parenchyma distant from injected sites. Local dissemination of the cancer cells was not found in any case. Therefore, PEIT seems to be a valuable therapy and may be an alternative to surgery in some cases.

Adult↗