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.

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.

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.

Gastroprotective properties of ebrotidine. A review

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) is a new antiulcer drug which combines the properties of an H2-receptor antagonist with those of a cytoprotective agent. The cytoprotective properties of ebrotidine are not dependent upon endogenous prostaglandin generation, but stem from the ability of the drug to induce mucosal responses manifested in the enhanced physicochemical characteristics of mucus gel. These include the increase in mucus gel dimension, viscosity, hydrophobicity and hydrogen ion retardation capacity. Improvements in mucus gel protective qualities with ebrotidine are directly related to the ability of the drug to enhance the synthesis and secretion of sulfo- and sialomucins and phospholipids of gastric mucus and to promote mucin macromolecular assembly. An equally important property of ebrotidine in promotion of ulcer healing is its capability to enhance the gastric mucosal expression of integrin receptors for the interaction with proteins of the extracellular matrix such as laminin. Furthermore, the accelerated ulcer healing with ebrotidine is reflected in a marked increase in the mucosal expression of EGF and PDGF receptors. The drug has also been shown to modulate the processes associated with cell cycle progression during ulcer healing, and is known to protect the gastric epithelial integrity from calcium imbalance. Thus, ebrotidine, unlike other H2-blockers, has a unique ability to promote the event essential for mucosal repair and the maintenance of mucosal integrity. These features make ebrotidine a drug of great potential in the treatment of ulcer disease.

Induction of acute gastritis and epithelial apoptosis by Helicobacter pylori lipopolysaccharide

BACKGROUND

The preservation of gastric mucosal homeostasis is a complex biologic process, controlled by a dynamic equilibrium of cell loss by apoptosis with that of cellular proliferation, and its abrogation is a prominent feature of Helicobacter pylori-associated gastritis. In this report, we show that H. pylori lipopolysaccharide induces histologic lesions typical of acute gastritis and that these changes are reflected in the increased epithelial cell apoptosis.

METHODS

The experiments were conducted with groups of rats subjected to intragastric surface epithelial application of the lipopolysaccharide at 50 and 200 micrograms per animal. The histologic assessment of the mucosal tissue and quantification of apoptotic epithelial cells was performed 2 and 10 days after the lipopolysaccharide treatment.

RESULTS

Histologic examination showed that H. pylori lipopolysaccharide at both doses within 2 days induced infiltration of lamina propria with lymphocytes and plasma cells, edema, hyperemia, and hemorrhage extending from the lamina propria to the surface of mucosa, and the effect persisted beyond the 10 days. The in situ DNA fragmentation assay showed that lipopolysaccharide caused a marked increase in epithelial cell apoptosis, with the numerous apoptotic cells present not only in the superficial epithelium but also deeper in the glands. The mean apoptotic index in the mucosa was 59% when assessed 2 days after the administration of the 50-microgram lipopolysaccharide dose and 71.9% after the 200-microgram dose, whereas in the sections assessed 10 days after the lipopolysaccharide treatment the apoptotic index averaged 46% for a 50-microgram dose and 76.8% for a 200-microgram dose. Moreover, the apoptotic index showed positive correlation (r = 0.71) with the grade of the induced inflammatory changes.

CONCLUSIONS

Our findings demonstrate that H. pylori lipopolysaccharide can cause gastric mucosal responses typical of acute gastritis and identify the lipopolysaccharide as a virulence factor responsible for the induction of gastric epithelial cell apoptosis by H. pylori.

Impact of particulate contamination in crystalloid cardioplegic solutions: studies by scanning and transmission electron microscopy

The amount of particulate matter present in Bretschneider's cardioplegic solution (HTK) was assessed by laser-mediated particle counting. Permissible levels of contaminant particles with a distribution of diameters between 0.2 and 20 microns were found. A significant further increase in the particle count was observed when the fluid was administered for clinical use, which resulted in the additional release of particles from, for example, the infusion kit, which included an in-line filter with pores of 270 microns. Filtration of the HTK solution by a terminal inline filter (0.2 micron) significantly reduced the number of particles. In order to determine the chemical composition and the potential hazards of the particulate material we used scanning electron microscopy in combination with energy dispersive X-ray analysis and transmission electron microscopy to examine specimens taken from heart tissue obtained from Göttinger minipigs after cardioplegia and from humans undergoing mitral valve replacement after cardioplegia and reperfusion. Particles of various diameters were found either to be plugging coronary capillaries, to be adherent to the endothelial layer, or to be engulfed by polymorphonuclear (PMN) granulocytes, which appeared to be activated. Some of the PMN granulocytes were apparent in the endothelial layer. It is recommended, therefore, that a terminal in-line filter (0.2 micron) should be routinely used.

Helicobacter pylori lipopolysaccharide induces gastric epithelial cells apoptosis

H. pylori is recognized as a primary etiologic factor in the pathogenesis of gastric disease. Here, we assessed the effect of intragastric administration of H. pylori lipopolysaccharide at 50 and 200 micrograms dose on the epithelial cell apoptosis. Histological examination of the mucosal tissue two days following the treatment revealed that lipopolysaccharide at both doses induced in the rat stomach mucosal inflammatory responses typical of gastritis. The in situ DNA fragmentation assay demonstrated that these changes were associated with a marked increase in gastric epithelial cell apoptosis. The apoptotic index in the controls averaged 0.3%, and increased dramatically to 59% with the lipopolysaccharide at 50 micrograms dose, while at the 200 micrograms dose the apoptotic index of 71.9% was attained. The results point towards cell wall lipopolysaccharide as a virulence factor responsible for the induction of gastric epithelial cell apoptosis by H. pylori.

Synchronized induction in bFGF and Cdk2 during gastric ulcer healing

The processes of gastric mucosal repair are regulated by growth factors triggering the signals for cell cycle progression. We examined the expression of gastric mucosal basic fibroblast factor (bFGF) and cyclin dependent kinase (p34Cdk2) at different stages of chronic ulcer healing. The results of assays revealed that ulcer healing was accompanied by an increase in mucosal expression of bFGF and Cdk2. A significant induction in bFGF and Cdk2 occurred by the 2nd day of ulcer healing, reached the respective maximums of 2.3- and 2.2-fold increase by the 4th day of healing, and remained still elevated (20%) on the 14th day when the ulcer was essentially healed. The results demonstrate a synchronized induction in bFGF and cell cycle regulatory kinase, Cdk2, with ulcer healing.

Susceptibility of growth factors to degradation by Helicobacter pylori protease: effect of ebrotidine and sucralfate

In this study, we investigated the susceptibility of the growth factors (EGF, bFGF, TGF beta and PDGF) to degradation by the protease elaborated by H. pylori and assessed the effect of antiulcer agents, ebrotidine and sucralfate, on this enzymatic action of the bacterium. The colonies of H. pylori were washed with saline, filtered to retain the bacteria, and the filtrate used as an enzyme source. The assays revealed that while EGF and beta FGF showed only marginal (5-7%) susceptibility to H. pylori protease, a 61.7% degradation occurred with PDGF and 62.3% with TGF beta. Introduction of ebrotidine or sucralfate to the assay system led to the reduction in the rate of growth factors degradation, which at 50 micrograms/ml ebrotidine reached the value of 85.1% for PDGF and 88.6% for TGF beta, while with sucralfate the optimal inhibition of PDGF (79.6%) and TGF beta (82.7%) degradation occurred at 200 micrograms/ml. The results demonstrate that PDGF and TGF beta are susceptible to H. pylori degradation and that antiulcer agents, ebrotidine and sucralfate are capable of counteracting this effect.

Salivary mucins in oral mucosal defense

1. Salivary mucins are well recognized as an important factor in the preservation of the health of the oral cavity. These large glycoproteins play a major role in the formation of protective coatings covering tooth enamel and oral mucosa, which act as a dynamic functional barrier capable of modulating the untoward effects of oral environment, and are of significance to the processes occurring within the epithelial perimeter of mucosal defense. 2. Based on macromolecular characteristics, the mucins in saliva fall into high (> 1000 kDa) and low (200-300 kDa) molecular weight forms. The two forms, although differ with respect to bacterial clearance ability, display virtually identical carbohydrate chain make-up, ranging in size from 3 to 16 sugar units. 3. Of the two mucin forms, the low molecular weight form more efficient in bacterial aggregation, predominates in saliva and oral mucosal mucus coat of caries-resistant individuals, while the level of the high molecular weight form is higher in caries-susceptible subjects. The saliva of caries-resistant individuals also exhibits greater activity of protease capable of conversion of the high molecular weight mucin to the low molecular weight form. 4. The bacterial aggregating activity of salivary mucins appears to be associated with sulfomucins rather than sialomucins. While the removal of sialic acid causes only partial loss in mucin aggregating capacity, a complete loss in the bacterial aggregating activity occurs following mucin desulfation. 5. The mucins in oral mucosal mucus coat interact with the epithelial surfaces through specific membrane receptors. This interaction apparently involves the carbohydrate moiety of mucin molecule and may be rendered vulnerable to disruption by opportunistic bacteria colonizing the oral mucosa. 6. Salivary sulfo- and sialomucins actively participate in the modulation of the oral mucosal calcium channel activity through the inhibition of EGF-stimulated channel protein tyrosine phosphorylation. This function of salivary mucins is of paramount importance to mucosal calcium homeostasis.

[Does chronic oral treatment with beta-receptor blockers have an effect on positive inotropic therapy of coronary patients with adrenaline after extracorporeal circulation?]

For the prebypass period various authors have shown that patients on oral or intravenous beta blocking therapy respond to catecholamine treatment with marked increase in afterload and no change in cardiac index. Since positive inotropic therapy is usually not necessary until, but after termination of cardiopulmonary bypass, the question arises as to whether beta-blocking agents administered orally on the morning of the operation, can still have negative effects during this phase of the procedure.

PATIENTS AND METHODS

20 patients (NYHA classification II to III) undergoing coronary artery bypass grafting, half of them having been on chronic beta-adrenoceptor blocking therapy, were treated with 0.1 micrograms/kg/min adrenaline as an infusion, when following cardiopulmonary bypass cardiac index was < 2.4 l/min/m2 with left and/or right ventricular filling pressures being normal or raised. Haemodynamic monitoring consisted of ECG, direct arterial pressure, a pulmonary artery catheter and of an additional thermodilution catheter placed directly into the coronary sinus. The parameters looked at were mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), coronary perfusion pressure (CPP), total peripheral resistance (TPR), pulmonary capillary wedge pressure (PCWP), right atrial pressure (RAP), pressure work index (PWI), myocardial blood flow (MBF) and myocardial oxygen consumption (MVO2). Arterial and myocardial lactate levels were measured and from that myocardial lactate extraction and production were calculated. Measurements were made immediately following termination of cardiopulmonary bypass and then after 15, 30, 45 and 60 minutes under continuous infusion of adrenaline. In addition left ventricular pressure was measured via transseptal needle for calculation of myocardial contractility dp/dtmax directly after termination of cardiopulmonary bypass and 15 minutes later with adrenaline therapy. Prior to induction of anaesthesia and following termination of cardiopulmonary bypass blood samples were taken to measure plasma levels of the beta blocking drug.

RESULTS

All 10 patients on oral beta blocking therapy had plasma levels within the therapeutic range prior to induction of anaesthesia. Following cardiopulmonary bypass the plasma levels had fallen by 50% on average, but with 2 exceptions, they were still within the therapeutic range (Table 2). Irrespective of the fact whether preoperatively beta blockers had been taken, adrenaline caused a significant increase in contractility (Table 3), mean arterial pressure (Figure 1), heart rate (Table 3) and cardiac index (Figure 2). There was a comparable increase of pressure work index (Figure 5), myocardial blood flow (Figure 6) and myocardial oxygen consumption (Figure 7) in both groups. Effect on afterload was significantly different. In both groups MAP was increased but that was more marked in the presence of beta blockade (Figure 1). Total peripheral resistance fell in the group without preoperative beta blockade whereas in patients on preoperative beta blockade TPR increased by 100 dyn.s.cm-5 on average (Figure 4). As a consequence adrenaline infusion caused an increase in CPP only in the presence of beta blockade (Figure 3). In both groups adrenaline infusion caused an increase in arterial and myocardial lactate levels (Tables 6 and 7). Some patients without preoperative beta blockade showed myocardial lactate production whereas in the presence of beta blockade myocardial lactate extraction was found at all points of measurement (Figure 8).

CONCLUSION

Our results show, that observations made by various groups in the prebypass period on patients treated with beta blocking agents, which demonstrate dramatic increases in afterload with no improvement in cardiac index following catecholamine administration do not hold true for the post-bypass period. The reason could be a wash out effect of the Bretschneider cardioplegia on cardiac beta receptors.

Susceptibility of Helicobacter pylori to antimicrobial agents: effect of ebrotidine and ranitidine

Convincing evidence now exists that infection with H. pylori is a primary factor in the pathogenesis of gastric disease, and new therapy regimens include a combination of H2 blockers with antimicrobial agents. In this study, was assessed the effect of ebrotidine and ranitidine on the in vitro anti-H. pylori activity of amoxicillin, erythromycin, tetracycline, and metronidazole. The assays of the antiulcer drugs alone gave MIC value of 150 mg/L for ebrotidine and 1600 mg/L for ranitidine. Inclusion of ebrotidine in the antimicrobial agent assays evoked at its optimal concentration of 75 mg/L a 28% enhancement in the MIC of metronidazole, 2.5-fold enhancement in the MIC of erythromycin, 2-fold in amoxicillin and 1.7-fold in tetracycline, while ranitidine caused noticeable changes in the MIC values of the tested antimicrobial agents only a the dose of 1600 mg/L. The results demonstrate that ebrotidine enhances anti-H. pylori activity of antimicrobial agents at doses well below that of ranitidine.

Inhibition of gastric mucosal mucin receptor by H. pylori lipopolysaccharide: effect of ebrotidine

1. H. pylori infection causes the loss of mucus coat continuity and its patchy appearance. Here, we present evidence that the bacterium, through its cell wall lipopolysaccharide, disrupts the interaction between mucin and its mucosal receptor, and that ebrotidine is capable of counteracting this process. 2. The receptor for mucin, isolated from the solubilized gastric epithelial cell membrane by affinity chromatography on Sepharose-bound wheat germ agglutinin, displayed a molecular weight of 97 kDa and exhibited specific affinity towards mucin-coated surface. 3. The mucin binding to the receptor was susceptible to the inhibitin by H. pylori lipopolysaccharide and reached a maximum of 91%. This effect of the lipopolysaccharide was counteracted by ebrotidine, which caused a dose-dependent relief of the lipopolysaccharide inhibitory effect with maximum restoration in mucin-receptor binding of 51% at 60 microliters/ml ebrotidine. 4. The results show that H. pylori, through its lipopolysaccharide, is capable of disrupting the integrity of mucus perimeter of gastric mucosal defense and that antiulcer agent, ebrotidine, counteracts this untoward effect.

Calculated measures of performance in electrical impedance tomography using a finite-element model

A two-dimensional finite-element model of an electrical impedance tomographic phantom has been investigated. It is perceived that an understanding of the basic measurement system will enable the design of improved data collection hardware, e.g. the number and size of the electrodes. The presented model has sixteen electrodes spaced equidistantly on the perimeter and a centrally placed anomaly. The system is excited using the adjacent-electrode constant-current drive scheme. The size and conductivity of the anomaly are varied in order to investigate how the measurement system will behave to changes in input. Measures of the system's sensitivities to these variations in the anomaly are defined. The four measures derived from the calculated boundary voltages are contrast sensitivity, spatial or radial sensitivity, visibility and rms voltage difference. Results are presented for the four measures, showing how they vary with the parameters of the anomaly. In particular, these results show that there is a clear and distinct difference between spatial and contrast sensitivity. The relationship between the calculated visibility values and the conductivity contrast of the anomaly differs from that predicted theoretically, but is in agreement with the measured relationship. It can also be seen that the presented model is more than twice as sensitive to changes in an anomaly that is more resistive as compared to one that is more conductive than the background or surrounding material.

Inhibition of Helicobacter pylori urease activity by ebrotidine

Helicobacter pylori is considered a primary factor in the pathogenesis of gastric disease, and the successful mucosal colonization is linked to its urease activity. In this study, we assessed the effect of antiulcer agent, ebrotidine, on the in vitro activity of H. pylori urease. The results of assays showed a dose-dependent inhibition of the urease activity. A maximum inhibition (77%) in H. pylori urease activity occurred at 2.1 microM ebrotidine. A known H2-blocker, ranitidine, in a parallel experiment gave a maximal inhibition of 73% at a considerably higher concentration (6.4 microM). The results demonstrate that ebrotidine with its combined acid suppressant and anti-H. pylori activities offers an excellent choice in the treatment of H. pylori associated gastric disease.

Gastric mucus viscosity and Helicobacter pylori

Images

[Perforation of the heart wall--a rare complication after thoracic drainage treatment]

Complications after chest-tube treatment are rare if the correct technique is used. We describe a case of an iatrogenic perforation of the heart after bringing in a chest tube to treat a ventral pneumothorax during the postoperative intensive care treatment.

Enhancement in the protective qualities of gastric mucus by ebrotidine during duodenal ulcer healing

1. Gastric mucus from duodenal ulcer patients before and following therapy with a new antiulcer agent, ebrotidine, at 400, 600 and 800 mg dose was examined for changes in the physicochemical qualities and anti-H. pylori activity. 2. The results of physical measurements revealed that successful therapy with ebrotidine was accompanied by a 25% increase in gastric mucus viscosity, and a 20% increase in H+ retardation capacity, while its hydrophobicity increased by 11%. 3. The enhancement in the physical properties of mucus with ebrotidine therapy were also reflected in a marked (2.6-2.9-fold) increase in the proportion of the high molecular weight form of mucin. Furthermore, following therapy with ebrotidine, the gastric mucins showed a 36% higher content of sulfate as compared to that before the therapy. 4. Assays on the H. pylori aggregating titer of gastric mucin revealed that ebrotidine therapy at all three doses evoked a 4-fold increase in mucin anti-H. pylori activity. 5. The data demonstrate that duodenal ulcer therapy with ebrotidine leads to a marked improvement in the protective qualities of gastric mucus essential for the maintenance of mucosal integrity and enhances the inherent mucosal defense against H. pylori infection.

The protein kinase C-activated MAP kinase pathway of Saccharomyces cerevisiae mediates a novel aspect of the heat shock response

The PKC1 gene of budding yeast encodes a homolog of the alpha, beta, and gamma isoforms of mammalian PKC that is proposed to regulate a MAPK-activation pathway. Mutants in this pathway undergo cell lysis resulting from a deficiency in cell wall construction when they attempt to grow at elevated temperatures. We show that the PKC1-regulated pathway is important for induced thermotolerance and that the MPK1 protein kinase (the MAPK of this pathway) is strongly activated by mild heat shock. This activation is sustained during growth at high temperature and is dependent on the function of pathway components proposed to function upstream of MPK1, including PKC1. Expression of genes under the control of known heat shock-inducible promoter elements (HSEs and STREs) was not compromised in PKC1 pathway mutants, indicating that this pathway mediates a novel aspect of the yeast heat shock response. We propose that the heat-induced signal for pathway activation is generated in response to weakness in the cell wall created during growth under thermal stress, perhaps as a result of increased membrane fluidity. Evidence is presented that the mechanism by which the cell detects this weakness is by measuring stretch of the plasma membrane.

Enhancement in gastric mucosal EGF and PDGF receptor expression with ulcer healing by sulglycotide

1. The effect of an antiulcer agent, sulglycotide, on mucosal expression of EGF and PDGF receptors with chronic ulcer healing was investigated. 2. Rats with experimentally-induced gastric ulcers were treated twice daily for 14 consecutive days, either with sulglycotide at 200 mg/kg or vehicle, and at different stages of treatment used for quantitation of gastric mucosal EGF and PDGF receptors. 3. The ulcer healing was accompanied by an increase in mucosal expression of both types of receptors. A 1.8-fold increase in EGF and 3.1-fold increase in PDGF receptors occurred by the 4th day following the development of ulcer and reached a maximum of 2.4-3.9-fold increase by the 10-14th day. 4. Treatment with sulglycotide caused accelerated ulcer healing accompanied by a significant enhancement in the receptors expression. A 2.3- and 3.6-fold increase in EGF and PDGF receptor expression occurred by the 4th day of sulglycotide treatment, reaching a 5.5- and 5.6-fold respective increase by the 10th day when the ulcer essentially healed. 5. The results attest to the ability of sulglycotide to stimulate the gastric mucosal proliferative activities associated with ulcer healing.

Helicobacter pylori lipopolysaccharide inhibition of gastric mucosal somatostatin receptor

A gastric mucosal somatostatin receptor was isolated from the solubilized epithelial cell membrane by affinity chromatography on a column consisting of covalently coupled [D-Tryp8]SRIF-14 to Affi-Gel 10. The receptor protein displayed a molecular weight of 61kDa and exhibited specific affinity towards 125I-labeled [Tyr11]SRIF-14 with the optimum range of 4-8 micrograms/ml. The binding of somatostatin to its mucosal receptor was inhibited by lipopolysaccharide from H. pylori. The inhibitory effect was proportional to the concentration of lipopolysaccharide up to 50 micrograms/ml and reached a maximum of 94.1% inhibition. The results suggest that H. pylori, through its lipopolysaccharide, is capable of interfering with somatostatin regulatory effect on gastric mucosal G-cell function.

Antagonism of botulinum toxin-induced muscle weakness by 3,4-diaminopyridine in rat phrenic nerve-hemidiaphragm preparations

The effects of the potassium channel inhibitor and putative botulinum toxin antagonist 3,4-diaminopyridine (3,4-DAP) were investigated in vitro on the contractile properties of rat diaphragm muscle. In the presence of 100 pM botulinum neurotoxin A (BoNT/A), twitches elicited by supramaximal nerve stimulation (0.1 Hz) were reduced to approximately 10% of control in 3 hr at 37 degrees C. Addition of 3,4-DAP led to a rapid reversal of the BoNT/A-induced depression of twitch tension. In the presence of 100 microM 3,4-DAP, antagonism of the BoNT/A-induced blockade began within 30-40 sec and reached 82% of control with a half-time of 6.7 min. The beneficial effect of 3,4-DAP was well maintained and underwent little or no decrement relative to control for at least 8 hr after addition. Application of 1 microM neostigmine 1 hr after 3,4-DAP led to a further potentiation of twitch tension, but this action lasted for < 20 min. Moreover, neostigmine caused tetanic fade during repetitive stimulation. In contrast to the efficacy of the parent compound, the quaternary derivative of 3,4-DAP, 3,4-diamino-1-methyl pyridinium produced little or no twitch potentiation up to a concentration of 1 mM. The potassium channel blocker, tetraethylammonium, generated a transient potentiation followed by a sustained depression of twitch tensions. It is concluded that 3,4-DAP is of benefit in antagonizing the muscle paralysis following exposure to BoNT/A. Co-application of neostigmine or tetraethylammonium with 3,4-DAP, however, appears to confer no additional benefit.

Susceptibility of Helicobacter pylori to antimicrobial agents: effect of sulglycotide

H. pylori is regarded as a primary etiologic factor in gastric disease and the therapies now include a combination of antimicrobial agents with antiulcer drugs. Here, the effect of a new gastroprotective agent, sulglycotide, on the in vitro anti-H. pylori activity of metronidazole, erythromycin, tetracycline, and amoxycillin was assessed. The assays in the absence of sulglycotide gave MIC value 0.10mg/L for erythromycin, 0.12mg/L for amoxycillin, 0.15mg/L for tetracycline and 14mg/L for metronidazole, while sulglycotide alone gave MIC value of 20mg/L. The sulglycotide at its optimal dose (5mg/L) evoked a 4-fold enhancement in the MIC of amoxycillin, 5-fold in tetracycline, and 8.3-fold in erythromycin, while the MIC of metronidazole improved 3.5-fold at 10mg/L sulglycotide. The results point towards the advantage of combination therapy of sulglycotide and antibiotics for H. pylori eradication.

Helicobacter pylori aggregating activity of gastric mucin with ulcer healing by ebrotidine

The mucin isolated from gastric secretion of duodenal ulcer patients before and after therapy with a new antiulcer agent, ebrotidine, was assessed for H. pylori aggregating activity and macromolecular organization. Analyses of mucin molecular forms revealed that successful therapy with ebrotidine was accompanied by a 2.6-2.9-fold increase in the high molecular weight mucin form. The H. pylori aggregation inhibition assays showed that therapy with ebrotidine evoked a 4-fold increase in mucin anti-H. pylori titer. The changes in the functional properties of mucin following ebrotidine therapy were also accompanied by a 36% increase in the content of sulfomucin. The results demonstrate that ulcer therapy with ebrotidine lead to a marked enhancement in mucin's qualities associated with maintenance of gastric mucosal integrity and strengthening the indigenous defenses against H. pylori.