Biomedical subjects

A Slomiany

Publications and source records attributed to A Slomiany.

At least 55 records · Page 3Linked to original sources

PubMed1999

Role of caspase-3 and nitric oxide synthase-2 in gastric mucosal injury induced by indomethacin: effect of sucralfate.

BACKGROUND: Apoptosis is the process of programmed cell death characterized by a series of distinct biochemical and morphological changes which involve activation of caspase proteases cascade that remains under the regulatory control of nitric oxide. Here, we investigated the activity of a key apoptotic protease, caspase-3, and the expression of inducible nitric oxide synthase (NOS-2) and tumor necrosis factor-alpha (TNF-alpha) associated with gastric epithelial cells apoptosis during indomethacin-induced gastric mucosal injury, and evaluated the effect of antiulcer agent sucralfate on this process. METHODS: The experiments were conducted with groups of rats pretreated intragastrically with 200 mg/kg sucralfate or the vehicle, followed 30 min later by an intragastric dose of indomethacin at 60 mg/kg. The animals were killed 2 h later and their gastric mucosal tissue used for macroscopic assessment, assays of epithelial cells apoptosis and TNF-alpha, and the measurements of caspase-3 and NOS-2 activities. RESULTS: In the absence of sucralfate, indomethacin caused multiple hemorrhagic lesions occupying 29.3 mm2 of the corpus area, and accompanied by a 20-fold enhancement in gastric epithelial cells apoptosis and a 47% increase in mucosal expression of TNF-alpha, while NOS-2 showed an 11.9-fold induction and the activity of caspase-3 increased 3.9-fold. Pretreatment with sucralfate produced a 59.7% reduction in the extent of mucosal damage caused by indomethacin, a 41.2% decrease in the epithelial cells apoptosis and a 33.4% reduction in TNF-alpha, while the activity of caspase-3 decreased by 45% and that of NOS-2 showed a 44.7% decline. CONCLUSIONS: The results implicate caspase-3 in the process of indomethacin-induced gastric epithelial cells apoptosis, and point towards participation of NOS-2 in the amplification of the cell death signaling cascade. Our findings also show that sucralfate protection against gastric mucosal injury caused by indomethacin involves the suppression of NOS-2 and the apoptotic events propagated by caspase-3.

Animals↗

PubMed1999

Endothelin-1, interleukin-4 and nitric oxide synthase modulators of gastric mucosal injury by indomethacin: effect of antiulcer agents.

Endothelin-1 (ET-1), nitric oxide, and cytokines are recognized mediators of the inflammatory processes associated with gastric mucosal injury. In this study, we investigated mucosal expression of ET-1, interleukin-4 (IL-4), and the activity of constitutive nitric oxide synthase (cNOS) during indomethacin-induced gastric mucosal injury, and evaluated the effect of antiulcer agents on this process. The experiments were conducted with groups of rats pretreated intragastrically with ranitidine (100 mg/kg), ebrotidine (100 mg/kg), sulglycotide (200 mg/kg) or vehicle, followed 30 min later by an intragastric dose of indomethacin (60 mg/kg). The animals were killed 2 h later and their mucosal tissue subjected to macroscopic damage assessment and the measurements of epithelial cell apoptosis, ET-1, IL-4, and cNOS. In the absence of antiulcer agents, indomethacin caused multiple hemorrhagic lesions and extensive epithelial cell apoptosis, accompanied by a 20.7% reduction in IL-4, a 3.1-fold increase in mucosal expression of ET-1 and a 4.2-fold decline in cNOS. Pretreatment with H2-receptor antagonist, ranitidine produced a 15.7% reduction in the mucosal damage caused by indomethacin, 29.5% decrease in epithelial cell apoptosis and a 19.6% reduction in ET-1, while the expression of IL-4 increased by 10.8% and that of cNOS showed a 2-fold increase. The H2-blocker, ebrotidine, also known for its gastroprotective effects, reduced the indomethacin-induced lesions by 90.2%, epithelial cell apoptosis decreased by 61% and ET-1 showed a 58.2% decline, while IL-4 increased by 30.6% and that of cNOS showed a 3.1-fold increase. Pretreatment with gastroprotective agent, sulglycotide, led to a 51.2% reduction in the extent of mucosal damage caused by indomethacin, a 43.9% decrease in apoptosis, and a 63.5% decrease in ET-1, while the expression of cNOS increased by 3.4-fold and the level of IL-4 showed a 32.2% increase. The results suggest that an increase in vasoconstrictive ET-1 level combined with a decrease in regulatory cytokine, IL-4, and a loss of compensatory action by cNOS may be responsible for gastric mucosal injury caused by indomethacin. Our findings also point to a value of ebrotidine and sulglycotide in countering the untoward gastrointestinal side effects of NSAID therapy.

Animals↗

PubMed1999

Effect of ebrotidine on gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide.

UNLABELLED: Helicobacter pylori lipopolysaccharide is a primary virulence factor responsible for eliciting acute mucosal inflammatory responses associated with H. pylori infection. In this study, we applied the animal model of H. pylori lipopolysaccharide-induced acute gastritis to assess the effect of antiulcer agent, ebrotidine, on the gastric mucosal inflammatory responses by analyzing the interplay between the activity of a key apoptotic caspase, caspase-3, epithelial cell apoptosis, and the expression of inducible nitric oxide synthase (NOS-2). METHODS: Rats, pretreated twice daily with ebrotidine at 100 mg/kg, or the vehicle, were subjected to intragastric application of H. pylori lipopolysaccharide at 50 microg/animal, and after 4 additional days on the antiulcer drug or vehicle regimen their mucosal tissue used for histologic assessment, assays of epithelial cells apoptosis, and the measurements of caspase-3 and NOS-2 activities. RESULTS: In the absence of antiulcer agent, H. pylori lipopolysaccharide induced acute reaction characterized by the inflammatory infiltration of the lamina propria, hyperemia, and epithelial hemorrhage. This was accompanied by an 11.2-fold increase in epithelial cell apoptosis, a 6.5-fold induction in mucosal expression of NOS-2, and a 5.4-fold increase in caspase-3 activity. Treatment with H2-receptor antagonist ebrotidine, also known for its gastroprotective effects, produced a 50.9% reduction in the extent of mucosal inflammatory changes elicited by H. pylori lipopolysaccharide and an 82.5% decrease in the epithelial cells apoptosis, while the activity of caspase-3 decreased by 33.7% and that of NOS-2 showed a 72.8% decline. CONCLUSIONS: The findings implicate caspase-3 involvement in gastric mucosal inflammatory responses to H. pylori lipopolysaccharide, and point towards participation of NOS-2 in the amplification of the cell death-signaling cascade. Our study also demonstrate that ebrotidine exerts modulatory effect on the H. pylori-induced mucosal inflammatory responses by interfering with the events propagated by NOS-2 and caspase-3.

Acute Disease↗

PubMed1998

Enhancement in the protective qualities of gastric mucus with combination therapy of ebrotidine and amoxicillin for H. pylori eradication.

1. Gastric mucus from Helicobacter pylori-positive patients with active chronic gastritis type B, before and after successful combination therapy consisting of the H2 receptor antagonist ebrotidine (400 mg) and amoxicillin (1,000 mg) administered b.i.d., in the morning and at bedtime for a period of 2 weeks followed by administration of ebrotidine alone for the subsequent 4 weeks, was assessed for the changes in physicochemical properties associated with the mucosal protective potential and anti-H. pylori activity. 2. The results of physicochemical measurements revealed that eradication of H. pylori associated with the successful therapy for active chronic gastritis type B with ebrotidine-amoxicillin was accompanied by a 36% increase in gastric mucus hydrogen ion retardation capacity, a 1.5-2.1-fold increase in mucus gel viscosity and a 2.4-fold increase in its hydrophobicity. 3. The beneficial changes brought about by the ebrotidine-amoxicillin therapy in the physical properties of gastric mucus were also manifest in a 2.7-fold enhancement in the proportion of the high-molecular-weight polymeric mucin form responsible for the maintenance of gastric mucus gel integrity. 4. Moreover, assays of H. pylori aggregating titer of gastric mucus revealed that the successful combination therapy with ebrotidine and amoxicillin led to a 3.8-fold increase in mucin anti-H. pylori activity. 5. The results demonstrate that combination therapy with ebrotidine and amoxicillin for H. pylori eradication leads to a marked improvement in the protective qualities of gastric mucus essential for the preservation of mucosal integrity and enhances the inherent mucosal defense against H. pylori infection.

Adult↗

PubMed1998

Effect of sucralfate on gastric mucosal inflammatory responses induced by Helicobacter pylori lipopolysaccharide.

BACKGROUND: Helicobacter pylori lipopolysaccharide is emerging as a primary factor in the bacterium virulence, and its involvement in causing gastric mucosal responses typical of gastritis has recently been shown. In this study we investigated the effect of the antiulcer agent sucralfate on the expression of regulatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-4 (IL-4), and epithelial cell apoptosis during H. pylori lipopolysaccharide-induced acute gastritis. METHODS: The experiments were conducted with rats pretreated intragastrically twice daily for 3 days with sucralfate at 100 mg/kg or the vehicle. The rats were then subjected to intragastric surface epithelial application of H. pylori lipopolysaccharide at 50 microg per animal and maintained on the sucralfate or vehicle regimen for an additional 4 days. The animals were killed 16 h after the last dose, and their gastric mucosal tissue used for histologic assessment, quantitation of TNF-alpha and IL-4 expression, and the assay of epithelial cell apoptosis. RESULTS: In the absence of sucralfate, H. pylori lipopolysaccharide induced acute mucosal responses characterized by the inflammatory infiltration of the lamina propria, hyperemia, and epithelial hemorrhage. This was accompanied by an 11-fold increase in gastric epithelial cell apoptosis and a 9-fold enhancement of the mucosal expression of TNF-alpha, but the level of IL-4 fell by 15%. Intragastric administration of sucralfate produced a 62% reduction in the extent of mucosal damage caused by H. pylori lipopolysaccharide, a 51% decrease in the mucosal expression of TNF-alpha, and a 7-fold reduction in the extent of epithelial cell apoptosis, whereas the expression of IL-4 increased by 52%. CONCLUSIONS: Gastric mucosal inflammatory responses to H. pylori lipopolysaccharide are characterized by a massive enhancement of the proinflammatory cytokine TNF-alpha and epithelial cell apoptosis and repression of IL-4. Our data also show that sucralfate is capable of inducing expression of the regulatory cytokine IL-4 and the suppression of apoptotic events triggered in gastric mucosa by the increase in TNF-alpha that is elicited by H. pylori lipopolysaccharide.

Animals↗

PubMed1998

Induction of buccal mucosal apoptosis with chronic alcohol ingestion.

In this study we investigated buccal mucosal cells apoptosis and the expression of regulatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-4(IL-4) with chronic ethanol ingestion. The buccal mucosa of rats maintained for 23 days on alcohol-containing and control liquid diet was assessed for IL-4 and TNF-alpha content, and the extent of epithelial cells apoptosis. While the expression of TNF-alpha in alcohol diet group showed a significant increase (1.9-fold) over that of the controls, less apparent differences between the two groups were observed in the content of IL-4 (141.8 +/- 28.2 vs. 119.8 +/- 7.3 pg/mg protein). The DNA fragmentation assays revealed that alcohol diet group also exhibited a 3.5-fold enhancement in buccal mucosal cells apoptosis. Moreover, the apoptotic index showed positive correlation (r = 0.53) with the extent of induced changes in TNF-alpha. These results demonstrate that ethanol-induced buccal mucosal cells apoptosis is triggered by the enhancement in TNF-alpha expression.

Alcoholism↗

PubMed1998

Alterations in buccal mucosal endothelin-1 and nitric oxide synthase with chronic alcohol ingestion.

Endothelin-1 (ET-1) and nitric oxide are emerging key mediators in the maintenance of mucosal homeostasis, but little is known about these substances in soft oral tissue with alcohol abuse. Hence, we examined the expression of ET-1 and activity of the constitutive nitric oxide synthase (NOS) in buccal mucosa of rats subjected to chronic ethanol diet. The immunometric assays revealed the buccal mucosal level of ET-1 in the controls at 40.2 pg/mg protein and showed a 4.1-fold increase with alcohol diet to 166.2 pg/mg protein. The NOS assays established that comparing to the controls, the alcohol diet group exhibited a 57% decrease in buccal mucosal NOS activity. Moreover, the expression of ET-1 showed an inverse correlation (r = -0.75) with the extent of the induced changes in NOS. The results suggest that an increase in vasoconstrictive ET-1 levels combined with a loss of compensatory action by the constitutive NOS may be responsible for the weakening of oral mucosal defenses in alcoholics.

Alcoholism↗

PubMed1998

Activation of apoptotic caspase-3 and nitric oxide synthase-2 in buccal mucosa with chronic alcohol ingestion.

Apoptosis, the process of programmed cell death, involves activation of caspase proteases cascade that remains under the regulatory control of nitric oxide. In this study, we investigated the activity of a key apoptotic protease, caspase-3, and the expression of nitric oxide synthase-2 (NOS-2) associated with buccal epithelial cells apoptosis induced by chronic ethanol diet. The assays revealed that a 7.9-fold enhancement in buccal epithelial cells apoptosis, observed in the alcohol diet group, was accompanied by a 37.6-fold increase in caspase-3 activity and a 10.1-fold increase in NOS-2. Furthermore, the expression of NOS-2 showed a positive correlation (r = 0.92) with the extent of changes induced in caspase-3 activity. These results implicate caspase-3 in the process of alcohol-induced epithelial cells apoptosis, and point towards participation of NOS-2 in the amplification of the cell death signaling cascade.

Alcoholism↗

PubMed1998

Effect of chronic alcohol ingestion on buccal mucosal expression of bFGF and Cdk2 during ulcer healing.

In this study, we investigated the effect of chronic alcohol ingestion on the interplay between the receptor-bound basic fibroblast growth factor (bFGF-R) and the expression of cyclin-dependent kinase (Cdk2) in buccal mucosa during ulcer healing. Chronic ulceration was induced by a topical application of acetic acid to the buccal mucosa of rats maintained for 5 weeks on alcohol-containing or control liquid diet. In both groups, the ulcer healing was accompanied by an increase in buccal mucosal expression of bFGF and Cdk2. In the control group, the ulcer healed within 10 days and maximum induction in bFGF (2.6-fold) and Cdk2 (2.4-fold) occurred by the 2nd day of healing. In contrast, the alcohol diet group showed a marked delay in ulcer healing (14 days), associated with the shift in maximum of bFGF and Cdk2 expression to the 4-6th day, and the values were reduced by 35 to 38%. The findings show that chronic alcohol ingestion exerts detrimental effect on the signaling events initiated by bFGF-receptor activation and propagated by Cdk2 that propels the cell cycle progression essential for rapid mucosal repair.

Acetic Acid↗

PubMed1998

Induction of caspase-3 and nitric oxide synthase-2 during gastric mucosal inflammatory reaction to Helicobacter pylori lipopolysaccharide.

Helicobacter pylori lipopolysaccharide is recognized as a primary virulence factor evoking acute mucosal inflammatory reaction associated with H. pylori infection. We investigated the activity of a key apoptotic protease, caspase-3, and the expression of inducible nitric oxide synthase (NOS-2) during H. pylori lipopolysaccharide-induced acute gastritis. The assays conducted 4 days following intragastric dose of the lipopolysaccharide revealed a pattern of acute mucosal responses characterized by an 11.2-fold increase in epithelial cells apoptosis, inflammatory infiltration of the lamina propria, hyperemia, and epithelial hemorrhage. This was accompanied by a 5.4-fold increase in caspase-3 activity, while the mucosal expression of NOS-2 showed a 6.5-fold induction. The results implicate H. pylori lipopolysaccharide in the induction of NOS-2 expression, and point to its effect on activation of the signaling cascade involving caspase-3 in the process gastric epithelial cells apoptosis.

Acute Disease↗

PubMed1998

Role of basic fibroblast growth factor in the suppression of apoptotic caspase-3 during chronic gastric ulcer healing.

BACKGROUND: In the course of ulcer healing an array of factors compel mucosal cells to proliferate, differentiate, and migrate to the site of injury. The recognition of triggering cues requires close interaction between the regulatory proteins integrating the growth factor and cytokine- mediated signals that propel cells through the cycle events, or to signal apoptosis. In this study, we analyzed the interplay between mucosal expression of the receptor-bound basic fibroblast growth factor (bFGF-R) and cyclin-dependent kinase (Cdk2), and the activity of apoptotic protease, caspase-3, and constitutive nitric oxide synthase (cNOS) during chronic gastric ulcer healing. METHODS: The experiments were conducted with gastric mucosa of rats at different stages of acetic acid-induced chronic gastric ulcer healing. RESULTS: The ulcer onset (2 days following injury) was characterized by a massive epithelial apoptosis associated with a 33-fold increase in caspase-3 activity and a 7.6-fold drop in cNOS, while the mucosal expression of Cdk2 fell by an 18% and that of bFGF-R by 12%. The ulcer healing was accompanied by a rapid elevation in bFGF-R and Cdk2, and a slow recovery in cNOS activity, while the caspase-3 activity and epithelial apoptosis showed a marked decline. The bFGF-R and Cdk2 reached their maximums of 2.2-2.3-fold at 4-6 day of healing, while the caspase-3 activity and the apoptotic DNA fragmentation showed a 3-fold decline by the 7th day of healing. However, the activity of cNOS remained about 50% lower than that of the controls. CONCLUSIONS: Taken together, these results provide strong indications that the initial phase of ulcer healing involves the inhibition of apoptotic caspase activities by a signaling events initiated by bFGF-receptor activation and propagated by the regulatory kinases that propel the cell cycle progression. Our findings also point towards participation of cNOS in the suppression of proapoptotic activities in gastric mucosa.

Animals↗

PubMed1998

Effect of ethanol on intracellular vesicular transport from Golgi to the apical cell membrane: role of phosphatidylinositol 3-kinase and phospholipase A2 in Golgi transport vesicles association and fusion with the apical membrane.

The study of ethanol effects on intracellular transport and membrane biogenesis in rat hepatocytes revealed that, during synthesis of transport vesicles, the cytosolic phosphatidylinositol 3-kinase incorporated into the membrane of Golgi transport vesicles and a portion of the vesicular phosphatidylinositol was phosphorylated to phosphatidylinositol 3-phosphate. Association of the enzyme with Golgi transport vesicles and the transport to the apical portion of the cell membrane was not affected by 0 to 120 mM ethanol, but was dependent on the presence of the p85 subunit of the phosphatidylinositol 3-kinase. In the presence of ATP-enriched cytosol and calcium ions, association of Golgi transport vesicles with the apical membrane was followed by phospholipase A2-specific hydrolysis of phosphatidylinositol 3-phosphate and incorporation of the transport vesicle membrane into the apical membrane. Association of Golgi transport vesicles with apical membranes was not affected by preincubation of the cell membrane or Golgi transport vesicles with 0 to 120 mM ethanol, but was inhibited when the p85 phosphatidylinositol 3-kinase was incorporated into the membrane before incubation with Golgi transport vesicles. The fusion of Golgi transport vesicles with the apical membrane and generation of lysophosphatidylinositol 3-phosphate and arachidonate was inhibited with EGTA or after depletion of ATP from cytosol. Results of these studies provide evidence that phosphatidylinositol 3-kinase and phospholipase A2 activities are crucial for the final step of exocytotic transport. The process consists of two stages. First, the p85 subunit of phosphatidylinositol 3-kinase is involved in the specific association of the vesicle with membrane receptor, and that is followed by phospholipase A2-specific lysophospholipid generation, perturbation of the membranes, and fusion of the transport vesicle membrane with the apical membrane. Addition of ethanol to the in vitro transport system decreased production of Golgi transport vesicles, but had no effect on their association with apical membrane or fusion with the membrane.

Animals↗

PubMed1997

Reversal of gastric somatostatin receptor inhibition by Helicobacter pylori lipopolysaccharide with ebrotidine and sulglycotide.

1. Among the consequences of H. pylori infection is an increase in gastric acid secretion due to the impairement in feedback inhibition by somatostatin. Here, we show that lipopolysaccharide from H. pylori inhibits the binding of somatostatin to gastric mucosal receptor, and that antiulcer agents, ebrotidine and sulglycotide, are capable of countering this effect. 2. The somatostatin receptor was prepared from the solubilized gastric mucosal epithelial cell membranes by affinity chromatography on Affi-Gel-bound [D-Tryp8] SRIF-14 and used in the binding assays for 125I-labeled somatostatin in the presence of H. pylori lipopolysaccharide and antiulcer agents. 3. The assays revealed a dose-dependent inhibition in the receptor-somatostatin binding by the lipopolysaccharide which reached a maximum of 94.1%. The effect of H. pylori lipopolysaccharide was countered by ebrotidine and sulglycotide, which at their optimal doses produced 94.9% and 84% restoration in somatostatin-receptor binding, respectively. 4. The results demonstrate that the antiulcer agents, ebrotidine and sulglycotide, possess the ability to counteract the H. pylori interference with somatostatin regulatory effect on gastric acid secretion.

Animals↗

PubMed1997

Cell cycle progression during gastric ulcer healing by ebrotidine and sucralfate.

1. The effect of antiulcer agents, ebrotidine and sucralfate, on the expression of gastric mucosal proliferating cell nuclear antigen (PCNA) and cyclin-dependent kinase (p34Cdk2) during chronic ulcer healing was examined. 2. Rats with experimentally induced gastric ulcers were treated twice daily for 14 days with either ebrotidine at 100 mg/kg, sucralfate at 100 mg/kg or vehicle, and at different stages of treatment their stomachs were used for quantitization of gastric mucosal PCNA and Cdk2 expression. 3. The assays revealed that the ulcer healing was accompanied by a marked elevation in mucosal expression of PCNA and Cdk2. The maximum increase in PCNA (4.7-fold) occurred by the second day of healing, and the expression of Cdk2 reached a maximum increase (2.3-fold) by the fourth day. 4. Accelerated ulcer healing with ebrotidine (7 days) and sucralfate (8 days) treatments was reflected in a significant enhancement of PCNA and Cdk2 expression. By the second day of treatment, ebrotidine evoked a 15-fold increase in PCNA expression, and sucralfate produced an 11.8-fold enhancement. The mucosal expression of Cdk2 attained a maximum of 4.3-fold increase over that of the controls by the sixth day of healing with ebrotidine, and a fivefold increase in Cdk2 expression occurred by the fourth day of ulcer treatment with sucralfate. 5. The findings implicate cell cycle regulatory proteins in the processes to leading to mucosal repair and suggest that the two drugs exert a similar effect on the expression of proteins that control cell cycle progression.

Animals↗

PubMed1997

Suppression of Helicobacter pylori urease activity by sucralfate and sulglycotide.

The effect of gastroprotective agents, sucralfate and sulglycotide, on the in vitro activity of H. pylori urease was investigated. The bacterium was subjected to sonication, centrifuged, and the supernatant used as an enzyme source. The assays revealed that the rate of urea degradation was proportional to enzyme protein up to 100 micrograms and remained constant with time for 10 min. Introduction of sucralfate or sulglycotide to the assay system led to the reduction in the rate of ammonia production. With both drugs the optimal inhibition was attained at 10 micrograms/ml, at which dose a 63.1% decrease in urease activity occurred with sucralfate and a 70.2% inhibition was obtained with sulglycotide. The findings demonstrate that the inhibitory action of sucralfate and sulglycotide on H. pylori urease activity may be of value in the treatment of gastric disease associated with H. pylori infection.

Ammonia↗

PubMed1997

Gastric mucosal apoptosis induced by ethanol: effect of antiulcer agents.

In this study, we investigated gastric epithelial cells' apoptosis and tumor necrosis factor-alpha (TNF-alpha) expression with ethanol-induced mucosal injury, and the effect of antiulcer agents on this process. Rats received intragastric pretreatment with the agent or vehicle followed 1h later by ethanol, and after 30 min the gastric mucosa was assessed for TNF-alpha and apoptosis. In the absence of antiulcer agents, ethanol caused extensive mucosal lesions accompanied by a 9.5-fold enhancement in apoptosis and a 2.5-fold increase in TNF-alpha. Pretreatment with omeprazole evoked a 54% reduction in TNF-alpha, but had no effect on ethanol-induced mucosal damage or apoptosis, the sucralfate reduced the extent of mucosal damage by 95%, apoptosis by 39% and TNF-alpha by 52%, while ebrotidine not only prevented mucosal injury and rise in TNF-alpha, but also caused a 70% reduction in epithelial cells' apoptosis. The results demonstrate that ethanol-induced gastric epithelial cells apoptosis triggered by the enhancement in mucosal TNF-alpha is efficiently counteracted by ebrotidine.

Animals↗

PubMed1997

Helicobacter pylori lipopolysaccharide inhibition of gastric somatostatin receptor: effect of sucralfate.

In this study, we investigated the inhibitory effect of Helicobacter pylori lipopolysaccharide on the binding of somatostatin to gastric epithelial cell membrane receptor, and assessed the effect of antiulcer agent, sucralfate, on this process. The assays conducted with the somatostatin receptor, purified from the solubilized epithelial cell membranes by affinity chromatography on Affi-Gel-[D-Tryp8]SRIF-14, revealed a dose-dependent inhibition in receptor-somatostatin binding by the lipopolysaccharide which reached a maximum of 94.1%. This effect of H. pylori lipopolysaccharide was countered by sucralfate that produced a 92.5% restoration in receptor-somatostatin binding at 70 micrograms/ml of the drug. The findings demonstrate that sucralfate is capable of reversing the interference by H. pylori lipopolysaccharide with somatostatin-receptor binding on gastric mucosal G-cells.

Animals↗

PubMed1997

Effect of ethanol on gastric mucus glycoprotein synthesis, translocation, transport, glycosylation, and secretion.

The effect of ethanol on mucus glycoprotein synthesis, intracellular modification, transport, glycosylation, and secretion was studied in rat gastric mucous cells. Preincubation of the in vitro translation mixture containing gastric mucous cells mRNA for 60 min with 0 to 120 mM ethanol caused a decrease in the synthesis of mucus glycoprotein apopeptide by up to 40%. The reduction in translation was time- and ethanol concentration-dependent. After 60 min, translation in the presence of 30, 60, and 120 mM ethanol decreased to 83.3 +/- 2.3%, 75.5 +/- 0.4%, and 63.6 +/- 2.6%, respectively. The experiments conducted with endoplasmic reticulum microsomes, preincubated with ethanol, and used in the studies of cotranslational translocation of the apomucin showed a 20% decrease in the transfer of mucus glycoprotein apopeptide to the lumen of endoplasmic reticulum microsomes. In the presence of ethanol, processing of mucus glycoprotein apopeptide in Golgi was also inhibited. During the initial 30 min of incubation with 0 to 120 mM ethanol, glycosylation seemed to proceed at the same rate in the samples with and without ethanol. However, during consecutive 30 min of incubation, glycosylation in the presence of 60 mM ethanol decreased by 30 to 35%, and with 120 mM ethanol was completely inhibited. Measurements of the effect of ethanol on the discharge of mucus glycoprotein from the intracellular stores revealed that, on average, the secretory output of the rat gastric mucosa exposed to ethanol liquid diet for 8 weeks decreased by 77% or more, and adherence of the glycoprotein to the gastric epithelium was weakened. Results indicate that ethanol inhibits synthesis, transport, and processing of gastric mucus glycoprotein, and that the processes taking place in different intracellular compartments contribute in the additive fashion and, are reflected in a dramatic decrease in the delivery of mucus glycoprotein to the gastric epithelial surfaces.

Animals↗