Expression of constitutive nitric oxide synthase in rat and human gastrointestinal tract.

The aim of this study was to determine the expression of constitutive NO synthases (ecNOS and bNOS) at the protein level in rat and human gastrointestinal tract. We established a quantitative Western blotting method for detection and quantification of ecNOS and bNOS in both species. Human gastric fundus was further analyzed by immunohistochemistry. EcNOS expression at the protein level could be quantified in different organs of the rat gastrointestinal tract and in human gastric mucosal biopsies. Immunohistochemistry of gastric fundus revealed that immunoreactivity for ecNOS was localized mainly in the endothelium of small vessels. In rats, expression of bNOS at the protein level was highest in esophagus. By means of immunohistochemistry of human gastric fundus, immunoreactivity was detected mainly in the plexus of Auerbach. We conclude that isoforms of constitutive nitric oxide synthase can be identified and quantified at the protein level both in rat and human gastrointestinal tract. The presence of bNOS in nerve tissue supports previous observations that NO serves as a transmitter in non-adrenergic, non-cholinergic nerves in human esophagus and stomach. The observation that ecNOS has been found mainly in endothelial cells suggests the involvement of NO in the regulation of mucosal blood flow.

Gastric electrical stimulation results in improved metabolic control in diabetic patients suffering from gastroparesis.

AIMS/HYPOTHESIS: Symptoms of gastroparesis possess a heavy impact on the quality of life; delayed gastric emptying may result in poor metabolic control in diabetics. Gastric electrical stimulation (GES) has recently been introduced as a treatment option in patients with drug refractory gastroparesis to increase the quality of life by alleviating nausea and vomiting frequencies. However, the effect of GES on metabolic control has not been assessed yet. METHODS: We performed a prospective single center study on the long-term effect (12 months) of continuous high-frequency/low-energy GES on symptoms, gastric emptying (measured scintigraphically), and metabolic control (HbA1c) in insulin-dependent diabetic subjects suffering from drug-refractory gastroparesis for more than one year. RESULTS: Seventeen (12 female, 5 male) patients entered the study; all were available for analysis at all time points. No therapy-associated adverse events occurred. Weekly vomiting and nausea frequencies decreased significantly at 6 and 12 months. Gastric retention rates improved significantly from 83 % (2 h) and 38 % (4 h) to 35 % (2 h)/14 % (4 h) and 25 % (2 h)/17 % (4 h) at 6 and 12 months, respectively. HbA1c values were lowered in all 17 subjects; initially, all HbA1c values were above 7.5 %; at 6 and 12 months, mean values had significantly decreased from 8.6 % to 6.2 % and 6.5 %, respectively. CONCLUSIONS/INTERPRETATION: Gastric electrical stimulation offers symptom control in diabetics with drug-refractory gastroparesis and decreases gastric retention. This study, for the first time, documents a positive effect of this therapy on metabolic control as indicated by HbA1c, a surrogate marker of the risk of diabetic complications.

From nerves and hormones to bacteria in the stomach; Nobel prize for achievements in gastrology during last century.

Rapid progress in gastroenterological research, during past century, was initiated by the discovery by W. Prout in early 18th century of the presence of inorganic, hydrochloric acid in the stomach and by I.P. Pavlov at the end of 19th century of neuro-reflex stimulation of secretion of this acid that was awarded by Nobel prize in 1904. Then, J. W. Black, who followed L. Popielski's concept of histamine involvement in the stimulation of this secretion, was awarded second Nobel prize in gastrology within the same century for the identification of histamine H2-receptor (H2-R) antagonists, potent gastric acid inhibitors, accelerating ulcer healing. The concept of H2-R interaction with other receptors such as muscarinic receptors (M3-R), mediating the action of acetylocholine released from local cholinergic nerves, and those mediating the action of gastrin (CCK2-R) on parietal cells, has been confirmed both in vivo studies and in vitro isolated parietal cells. The discovery of H2-R antagonists by Black and their usefulness in control of gastric secretion and ulcer healing, were considered as real breakthrough both in elucidation of gastric secretory mechanisms and in ulcer therapy. Discovery of even more powerful gastric acid inhibitors, proton pump inhibitors (PPI), also highly effective in acceleration of ulcer healing was, however, not awarded Nobel prize. Unexpectedly, two Australian clinical researchers, R.J. Warren and B.J. Marshall, who discovered in the stomach spiral bacteria, named Helicobacter pylori, received the third in past century Nobel prize in gastrology for the finding that this bacterium, is related to the pathogenesis of gastritis and peptic ulcer. They documented that eradication of H. pylori from the stomach, using antibiotics and potent gastric inhibitors, not only accelerates healing of ulcer but also prevents its recurrence, the finding considered as greatest discovery in practical gastrology during last century. Thus, the outstanding achievements in gastroenterology during last century have been awarded by three Nobel prizes and appreciated by millions of ulcer patients all over the world.

Comparison of sucralfate and ranitidine in gastroprotection against alcohol in humans.

This endoscopic study was designed to assess histologic and functional features of human gastric mucosal injury by 40 percent ethanol, and to compare the gastroprotective effects of sucralfate with those of ranitidine or sucralfate combined with ranitidine against ethanol damage. A group of 16 young subjects with normal gastric mucosa were divided into two groups (A and B). Group A was pretreated for four days with either sucralfate alone (1 g four times per day) or placebo (one tablet four times per day). Group B received sucralfate (1 g four times per day) plus ranitidine (150 mg three times per day) or placebo plus ranitidine in a double-blind, randomized study. On the fifth morning, two hours after the last treatment, 100 ml of 40 percent ethanol spray was applied via an endoscope onto gastric mucosa. In placebo-treated subjects, ethanol caused widespread endoscopic damage (score = 2.43) with histologic disruption of surface epithelium and deep necrotic lesions accompanied by a decrease of mucosal potential difference from -41.3 to -15.8 millivolts. Pretreatment with sucralfate significantly reduced endoscopic damage (score = 0.75). The surface epithelium was disrupted, but necrotic lesions were greatly reduced and potential difference decreased to -27.1 millivolts. Ranitidine alone or combined with sucralfate did not prevent ethanol-induced histologic or functional changes in the mucosa. Ethanol produces pronounced mucosal damage that can be almost completely prevented by sucralfate.

Helicobacter pylori-positive peptic ulcer patients do not adapt to aspirin.

BACKGROUND: Recent studies indicate that eradication of Helicobacter pylori might prevent peptic ulcer formation in patients treated with non-steroidal anti-inflammatory drugs (NSAIDs). On the other hand, gastric adaptation after repeated exposures to aspirin (ASA) is well documented but the influence of H. pylori on this process remains to be elucidated. AIM: To compare gastric damage and adaptation following repeated exposures to ASA in a group of patients with H. pylori infection, before and after eradication of the bacterium, and in H. pylori-negative controls. METHODS: Eight healthy volunteers without H. pylori infection and eight patients with duodenal ulcer (DU) history and H. pylori infection before and after H. pylori eradication were given ASA 2 g/day for a period of 14 days. Mucosal damage was evaluated by endoscopy and histology of biopsy samples. Gastric microbleeding, DNA synthesis in the gastric mucosa and mucosal expression, as well as luminal content of transforming growth factor-alpha (TGFalpha) were determined on days 0, 3, 7 and 14 of the ASA course. RESULTS: In all patients aspirin-induced gastric damage reached a maximum on day 3. In H. pylori-positive patients, this damage was maintained at a similar level up to day 14, whereas in H. pylori-negative controls and H. pylori-eradicated patients this damage significantly lessened on day 14 and was accompanied by elevated DNA synthesis as well as increased mucosal expression and luminal release of TGFalpha.

Effect of basic fibroblast growth factor on gastric ulcer healing and its own mRNA expression.

BACKGROUND: The application of an acid-stable mutein of basic fibroblast growth factor (bFGF) called CS23 results in acceleration of ulcer healing. The modes by which this cytokine exerts these effects are not yet completely understood. AIM: To describe the pattern of bFGF-mRNA expression during ulcer healing and to examine the effects of exogenously applied CS23 on gastric ulcer healing in an animal model. METHODS: The speed of healing of gastric ulcers, expression of extracellular matrix gene mRNAs such as pro alpha(I) collagen (by non-radioactive in situ hybridization), cellular proliferation evidenced by the display of PCNA (by immunohistochemistry), angiogenesis, and the feedback of this growth factor on its own mRNA expression pattern were used to evaluate the effects of CS23 on rat gastric ulcer healing in an animal model. RESULTS: CS23 accelerates gastric ulcer healing at 7, 14 and 21 days after ulcer induction. We found an increase in connective tissue beneath the ulcer bed in treated animals in comparison to controls. The expression of PCNA as well as pro alpha(I) collagen mRNA was markedly increased in ulcers, yet there was no distinct difference between treatment arms. In contrast, the density of microvessels was significantly increased in the submucosa of ulcers by CS23 application. bFGF-mRNA expression is up-regulated in the submucosa during early ulcer healing; this increase diminishes within days but can be restituted by the exogenous application of CS23. CONCLUSIONS: CS23 speeds gastric ulcer healing and significantly increases the density of microvessels in the ulcerated tissue without affecting the numbers of proliferating cells or the transcription of collagen mRNA. In addition, it augments the expression of bFGF-mRNA during the later stages of healing, suggesting a positive feedback loop.

Endogenous nitric oxide in the regulation of gastric secretory and motor activity in humans.

BACKGROUND: Studies in animals have shown that nitric oxide (NO) affects gastric secretory and motor functions. However, little information is available about the involvement of this substance in the control of gastric secretory and motor activity in man. METHODS: This study, performed on 18 healthy, Helicobacter pylori-negative volunteers, was designed to evaluate the role of NO in the control of gastric acid secretion and of gastrin and somatostatin release in response to ordinary feeding (group A) and on gastric motor and electrical activity (group B). Gastric acid secretion was determined by means of intragastric pH-metry before and after feeding with a semi-liquid meal. Plasma levels of gastrin and somatostatin were measured using specific radioimmunoassays. Gastric emptying rate was measured using the 13C-acetate breath test, antral motor activity using a manometric catheter and myoelectric activity using cutaneous electrogastrography. Studies were repeated following pre-treatment with NG-monomethyl-L-Arginine (L-NMMA), L-Arginine (L-Arg) or their combination. RESULTS: L-NMMA delayed the recovery of intragastric pH to the pre-meal value, and suppressed postprandial gastrin release while increasing the plasma somatostatin level. L-Arg did not affect postprandial pH and plasma hormones, but reversed L-NMMA-induced alterations in intragastric pH and in plasma gastrin and somatostatin levels. Both postprandial antral motor activity (motility index) and gastric emptying significantly increased in tests with L-NMMA, but this was not observed when L-NMMA was given in combination with L-Arg or when L-Arg alone was used. The gastric electrical pattern, as measured by cutaneous electrogastrography, was not affected by L-NMMA, L-Arg or their combination. CONCLUSIONS: (1) Endogenous NO appears to be involved in the regulation of postprandial gastric acid secretion. This effect may be mediated by the changes in release of gastrin and somatostatin. (2) Endogenous NO delays gastric emptying and antral motor activity without affecting gastric myoelectrical activity.

Role of reactive oxygen metabolites in aspirin-induced gastric damage in humans: gastroprotection by vitamin C.

BACKGROUND: The roles of active oxygen metabolites and anti-oxidative defenses in aspirin (ASA)-induced gastric damage have been little studied. AIM: We determined the effects of aspirin (400 mg b.d.) with or without vitamin C (480 mg b.d.) for 3 days on gastric mucosa in human volunteers. METHODS: Gastric injury was assessed endoscopically; gastric blood flow, reactive oxygen release (quantified by chemiluminescence), lipid peroxidation, myeloperoxidase, superoxide dismutase and glutathione peroxidase activity and intragastric vitamin C content were measured. Expression of superoxide dismutase and glutathione peroxidase mRNAs was assayed semi-quantitatively. RESULTS: ASA produced erosions, a marked increase in chemiluminescence, lipid peroxidation, and myeloperoxidase activity. It also resulted in a suppression of gastric blood flow, intragastric vitamin C levels, superoxide dismutase and glutathione peroxidase activities. The addition of vitamin C significantly attenuated gastric damage and reversed the effects of ASA on these parameters. Superoxide dismutase and glutathione peroxidase mRNAs were decreased in ASA-treated subjects; the addition of vitamin C restored their regular levels. CONCLUSIONS: (i) free radical-induced lipid peroxidation and suppression of antioxidizing enzymes play an important role in gastric damage induced by aspirin; (ii) increased myeloperoxidase activity suggests activated neutrophils to be the major source of these radicals; (iii) vitamin C protects against ASA-induced damage due to its anti-oxidizing activity.

Expression of endothelial cell-derived nitric oxide synthase (eNOS) is increased during gastric adaptation to chronic aspirin intake in humans.

BACKGROUND: Gastric adaptation to aspirin is well-documented. However, the mechanisms underlying the reduction of aspirin-induced mucosal damage despite continued ingestion of the drug remain poorly understood. METHODS: Eight healthy volunteers who received aspirin 1 g b.d. for 14 days were compared with eight placebo-dosed controls. Gastroscopy with mucosal biopsy was performed, and gastric mucosal blood flow was measured before and following 3, 7 and 14 days of aspirin treatment. At the same time points, tissue concentration and the content of prostaglandin E2 in the gastric juice were determined and expression of endothelial cell-derived nitric oxide synthase (eNOS) in mucosal biopsies was measured using Western blot analysis. RESULTS: Aspirin-induced mucosal damage that reached a maximum on day 3, declining significantly by day 14. Concomitantly, mucosal blood flow significantly increased on day 3 and returned to initial values on day 14. Aspirin intake led to a significant decrease in prostaglandin E2 concentration in the gastric mucosa and in gastric juice during the whole period of aspirin consumption. eNOS expression started to increase on day 7 in oxyntic mucosa and on day 3 in antral mucosa, reaching its highest values at the end of the consumption of aspirin. CONCLUSIONS: The human gastric mucosa adapts to prolonged aspirin intake, and this is accompanied by an increase in mucosal blood flow and reduced prostaglandin synthesis. Increase of mucosal eNOS expression might compensate for reduced prostaglandin synthesis and be responsible for gastric adaptation to chronic aspirin intake in humans.

Remodeling of extracellular matrix in gastric ulceration.

The quality of ulcer repair remains crucial for the stability of the injured tissue and for preventing recurrence. Therefore, we studied the temporo-spatial expression of the fibrillar and basement membrane collagens (types I, III, and IV), the collagenase MMP-2 as well as its inhibitor TIMP-1 before and after oral administration of basic fibroblast growth factor (b-FGF) over 30 days in acetic acid-induced rat gastric ulcers. The alterations and the exact location of the mRNA transcripts and their precipitated proteins were visualized by means of radioactive in situ hybridization and immunohistochemistry. Our data show that hybridization signals of procollagen I could first be identified 2 hours after ulcer induction. After 12 hours the ulcer was established and the mRNA was enhanced at the ulcer margin. After 24-48 hours the other procollagen transcripts were detected and all were further upregulated over the mesenchymal cells of all gastric layers up to 21 days, then declined at 30 days. In contrast, MMP-2 became prominent after 48 hours and up to 21 days. TIMP-1 was enhanced at 72 hours. After oral administration of b-FGF the transcriptional activity of the procollagens and MMP-2 was not significantly altered, while ulcer diameter was significantly reduced. We conclude that the early onset and long duration of collagens' expression points to their central structural and functional role in gastric ulcer healing. MMP-2 seems to be involved in both active ulceration and ECM remodeling. The timing of TIMP/MMP expression may be critical for proper restoration of gastric wall integrity.

Effect of Helicobacter pylori eradication on cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) expression during gastric adaptation to aspirin (ASA) in humans.

Gastric adaptation to aspirin is impaired in Helicobacter pylori infection, but the mechanisms underlying this phenomenon are unclear. In this study, we compared gastric mucosal expression of iNOS and COX-2 during 14 days of aspirin ingestion in the same subjects before and 3 months after eradication of H. pylori. Compared to non-infected controls, mucosal expression of COX-2 and iNOS was enhanced before and 3 months after eradication of H. pylori. During aspirin ingestion, mucosal expression of COX-2 remained unchanged before eradication of H. pylori, but increased gradually after successful antimicrobial treatment. Independent of H. pylori status, expression of iNOS increased at the beginning of aspirin intake, but then returned to initial values. We conclude that COX-2 but not iNOS might be involved in gastric adaptation to aspirin in humans and that this mechanism appears to be impaired in H. pylori infection.

Aspirin effects on gastric epithelial cell proliferation and cytokine expression.

Aspirin is known to cause gastric injury and to delay ulcer healing. The effects of aspirin on gastric epithelial cell function are heterogeneous; in contrast to injuring the mucosa, aspirin may also act beneficially by inducing adaptation; a mechanism that is poorly understood. We aimed to document the effects of different doses of aspirin on gastric epithelial cell function defined as proliferation, and secretion as well as mRNA expression of cytokines. Furthermore, we studied the effects of aspirin pretreatment on cytokine secretion as a potential element of gastric adaptation. The proliferative activity of three different gastric epithelial cell lines (AGS, KATO III, RGM-1) was assessed by (3)H-thymidine incorporation; secretion of growth factors PDGF-AB and VEGF into culture supernatant was documented by ELISA. mRNA transcripts of both cytokines were quantified by real time RT-PCR. Low doses of aspirin did not alter the proliferative dynamics in two of the three studied cell lines; high doses abolished proliferation. Secretion of PDGF-AB and VEGF increased during the first days of low dose aspirin exposition; higher concentrations led to a depletion of cytokines after an initial liberation in the case of VEGF, mRNA of which was also dose-dependently increased by aspirin. Seven-day pretreatment with low amounts of aspirin did not alter the secretory response of the epithelia caused by higher doses of this drug. The secretion of cytokines and proliferation of gastric epithelial cells are adversely effected by aspirin in a similarly dose-dependent fashion as the intended effects of this drug on platelet function and pain relief.

Role of oxidative stress in the pathogenesis of caerulein-induced acute pancreatitis.

In the last decade, the role of oxidative stress has been extensively evaluated in different experimental models of acute pancreatitis. This review shows that there is strong evidence that this stress occurs as an early phenomenon in pancreatic tissue in the course of caerulein-induced acute pancreatitis. Oxidative stress was documented in pancreatic tissue by means of methods showing generation of reactive oxygen species (e.g., chemiluminescence) and accumulation of products of reactive oxygen species-mediated lipid peroxidation. with concomitant depletion of enzymatic and low molecular weight antioxidants. Features of acinar cell injury and inflammation, especially pancreatic edema, show a marked improvement following treatment with a broad spectrum of antioxidants, platelet activating factor antagonists, or donors of nitric oxide (NO). Unfortunately, in most cases these beneficial effects are temporary and generally restricted to an early phase of the disease. However, results of well-designed clinical trials should finally evaluate the importance of oxidative stress-oriented treatment in acute pancreatitis in humans.

Effects of nitric oxide on antral motility and gastric emptying in humans.

OBJECTIVE: It has been suggested that nitric oxide is a nonadrenergic-noncholinergic (NANC) inhibitory neurotransmitter released by the nerves in the gastrointestinal tract. We studied the influence of nitric oxide on gastric emptying and antral motility using glyceryl trinitrate (GTN), a donor of nitric oxide and L-arginine as the substrate of nitric oxide synthase. DESIGN: Six male volunteers (aged 21-24 years) participated in this placebo-controlled, double-blind study. METHODS: We investigated the effects of 0.8 mg sublingual GTN, 300 mg/kg/h intravenous L-arginine or placebo on meal-stimulated antral motility and gastric emptying on four separate occasions. After an overnight fast, a 500 ml standard liquid meal was ingested and the gastric emptying rate assessed by ultrasound. The changes in antral cross-sectional areas were measured by ultrasonography and the antral motor activity was determined simultaneously using a multilumen perfused catheter. Blood samples were taken from fasted and fed patients before and after the administration of GTN, L-arginine or placebo to determine plasma glucagon and somatostatin levels. RESULTS: GTN at a sublingual dose of 0.8 mg and 300 mg/kg/h intravenous L-arginine significantly (P < 0.01) prolonged gastric emptying half-time, averaging 56 +/- 12 and 38 +/- 8 min, respectively, compared with the placebo control value (28 +/- 7 min). The antral motor activity, calculated as the motility index (number of contractions x mmHg/min) significantly decreased in both test series, i.e., after GTN from 375.5 +/- 185.1 (control) to 104.4 +/- 55.7 (P < 0.01) and after L-arginine from 401 +/- 76 (control) to 285 +/- 57 (P < 0.05). L-arginine given intravenously at a dose of 300 mg/kg/h significantly increased plasma glucagon and somatostatin in fasted patients and increased postprandially released glucagon without affecting postprandial plasma somatostatin levels. GTN did not affect plasma hormone levels. CONCLUSIONS: Our results indicate that (1) exogenous nitric oxide inhibits gastric emptying and antral motor activity, which could be useful in the treatment of patients with functional disturbances of gastric motility and emptying; and (2) the reduction in gastric emptying and antral motility observed after the administration of L-arginine results from changes in plasma enterohormone release rather than from the enhanced formation of endogenous nitric oxide.

Endoscopic and histological appearance of pancreatic metaplasia in the human gastric mucosa: a preliminary report on a recently recognized new type of gastric mucosal metaplasia.

Recently a new type of gastric mucosal metaplasia referred to as pancreatic metaplasia (pancreatic acinar metaplasia) has been recognized. The difference is characterized by the presence of epithelial cells with the cytoplasm strongly basophilic in the basal compartment, whereas in the middle and apical portions it is acidophilic and finely granular. In contrast to intramuscular heterotopic pancreas, foci of pancreatic metaplasia are located in the lamina propria of the gastric mucosa. They form lobules, small clusters, or may be single. The present series included 13 cases of pancreatic metaplasia found in gastroscopic specimens obtained from seven women and six men. We investigated the histological pattern and endoscopic changes. Based upon clinical data it was found that in five patients the gastric mucosa was defined as 'dichromatic'. It is possible that studies involving greater numbers of patients will permit closer correlation between the histological pattern of pancreatic metaplasia and the corresponding endoscopic changes.

Detection of Helicobacter pylori specific DNA in human atheromatous coronary arteries and its association to prior myocardial infarction and unstable angina.

BACKGROUND: Chronic infections have been proposed to play a role in the aetiology or progression of atherosclerotic plaques. Increased risk of coronary artery disease has been suggested in patients seropositive for Helicobacter pylori. AIM: To analyse coronary specimens in patients with severe (coronary artery disease) for Helicobacter pylori specific DNA. PATIENTS AND METHODS: Atherosclerotic plaques were obtained in 46 consecutive patients (9 female, 37 male, mean age 62.7+/-9.17 years) during coronary bypass procedures. Serum was analysed for IgG -/cagA-antibodies specific for Helicobacter pylori. Polymerase chain reaction and sequence analysis were used to identify bacterial DNA. Coronary artery biopsies from 19 autopsies without coronary artery disease were examined as a control group. RESULTS: Of the 46 coronary artery disease patients, 32 (69.6%) were Helicobacter pylori seropositive. Positive results for Helicobacter pylori DNA showed 18 seropositive and 4 seronegative (with anamnesis of eradication therapy). A total of 22 patients (47.8%) of the coronary artery disease group but none of controls revealed positive DNA. In the coronary artery disease group, a correlation between DNA presence and prior myocardial infarction (p=0.008) and unstable angina (p<0.001) was found. CONCLUSION: Identification of DNA in atherosclerotic plaques of patients with severe coronary artery disease supports the hypothesis that Helicobacter pylori infection may influence the development of atherosclerosis. Our results may indicate an direct involvement of Helicobacter pylori in the progression and instability of plaques in these patients.

Cholecystokinin in the control of gastric acid and plasma gastrin and somatostatin secretion in healthy subjects and duodenal ulcer patients before and after eradication of Helicobacter pylori.

BACKGROUND: Exogenous cholecystokinin (CCK) is known to effect gastric secretory and motor functions but its physiological role in the control of these functions in healthy subjects and duodenal ulcer (DU) patients is unknown. METHODS AND SUBJECTS: In this study involving four series of young healthy normal and DU subjects, the gastric secretory tests were performed under basal conditions and following stimulation by modified sham-feeding (MSF), i.v. infusion of caerulein, gastrin releasing peptide (GRP) or pentagastrin (p-gastrin) (series A), after 500 ml of standard meal without or with addition of 15% soybean oil (series B) or acidification of meal to pH 2.5 (series C), and finally after eradication of Helicobacter pylori (HP) (series D). Studies were carried out without or with the pretreatment with placebo or loxiglumide, a specific antagonist of type A CCK receptors. In series A, the gastric secretion obtained by aspiration technique was measured after secretagogues (MSF, caerulein, GRP or p-gastrin), whereas in series B, C, and D intragastric pH was measured before and after test meal and plasma gastrin, CCK and somatostatin were assayed by specific radioimmunoassays. RESULTS: In healthy subjects, MSF increased gastric acid outputs to about 36% of p-gastrin maximum and treatment with loxiglumide failed to affect this secretion. Standard meal enhanced acid output to about 50% of p-gastrin maximum and raised plasma levels of gastrin, CCK but not somatostatin. The pretreatment with loxiglumide resulted in further increase both in gastric acid secretion and plasma gastrin and CCK, while somatostatin level was significantly reduced. Infusion of graded doses of caerulein or GRP resulted in dose-dependent stimulation of gastric acid secretion reaching, respectively, 35% and 25% of p-gastrin maximum. When loxiglumide was added, the acid responses to caerulein and GRP were further increased by 2-3 folds, attaining a peak similar to the p-gastrin maximum. Administration of loxiglumide resulted in a significant increase in plasma gastrin and CCK responses to GRP, whereas plasma somatostatin was not significantly altered. Addition of fat to standard meal prolonged gastric emptying of this meal by about 50% both in healthy subjects and DU patients (series B). Fat in healthy subjects significantly increased and prolonged intragastric pH after the meal while reducing the increments in plasma gastrin and enhancing plasma CCK without alteration of plasma somatostatin. Pretreatment with loxiglumide significantly reduced postprandial pH from control 4.8 to 2.5 and reversed the changes in pH caused by addition of fat. The increments in plasma gastrin and CCK were markedly augmented, whereas those of somatostatin were attenuated. DU patients showed lower postprandial pH (3.0) in tests with or without fat and higher increments in plasma gastrin. CCK antagonism failed to affect significantly the pH profile or the increments in plasma gastrin or CCK. CCK antagonism failed to affect significantly the pH profile or the increments in plasma gastrin. Intragastric application of standard meal of pH 3.0 in healthy subjects and DU patients (series C) resulted in significantly lower median 3 h intragastric pH as compared to that after meal of pH 6.5. After pretreatment with loxiglumide, the median pH after meals of both pHs was significantly lower in healthy subjects but not in DU patients. This reduction in pH was accompanied by more pronounced increase in plasma gastrin response to a meal of pH 6.5 only in healthy controls but not in DU subjects and by a significant increase in plasma CCK and decrease in plasma somatostatin.

Electrical activity of canine gallbladder.

Our aims were to describe the myoelectrical activity in the single very thin layer of muscle of the canine gallbladder. The study was performed on 22 freshly removed canine gallbladders. Electrical activity was studied by the single sucrose-gap method and contractility of the tissue was measured simultaneously using a force transducer. The strips (15 x 1 mm) from different regions of gallbladder (fundus, corpus, neck) were cut in longitudinal, circular and oblique axes. The sucrose-gap apparatus together with connecting tubes, solutions and electrodes were kept at 37 degrees C and the initial tension applied to the tissue was set to 1 g. In 82.7% of recordings, spontaneous myoelectrical activity consisted of regular rhythmic changes in membrane potential similar to slow waves recorded in intestinal tissue. The overall mean frequency was 11.4 +/- 5.2 (mean +/- SD) cycles per min: 11.1 +/- 4.4 cycles per min in fundus, 11.9 +/- 6.2 cycles per min in corpus and 10.8 +/- 3.8 cycles per min in the neck of the gallbladder. In 84.2% of cases electrical activity correlated with mechanical activity and preceded it. No significant differences were seen between the electrical patterns in strips with different orientations or from the different regions of the gallbladder.

Brain-gut axis and its role in the control of food intake.

Gastrointestinal tract (GIT) and nervous system, both central (CNS) and enteric (ENS), are involved in two-way extrinsic communication by parasympathetic and sympathetic nerves, each comprising efferents fibers such as cholinergic and noradrenergic, respectively, and afferent sensory fibers required for gut-brain signaling. Afferent nerves are equipped with numerous sensors at their terminals in the gut related to visceral mechano- chemo- and noci-receptors, whose excitations may trigger a variety of visceral reflexes regulating GIT functions, including the appetitive behaviour. Food intake depends upon various influences from the CNS as well as from the body energy stores (adipocytes) that express and release the product of Ob gene, leptin, in proportion to fat stored and acting in long-term regulation of food intake. Leptin acts through receptors (Ob-R) present in afferent visceral nerves and hypothalamic arcuate nucleus (ARC), whose neurons are capable of expressing and releasing neuropeptide Y (NPY) and agouti related protein (AgRP) that activate the ingestive behaviour through paraventricular nucleus (PVN) (iVfeeding centerli). In addition, to this long-term regulation, a short-term regulation, on meal-to-meal basis, is secured by several gut hormones, such as cholecystokinin (CCK), peptides YY (PYY) and oxyntomodulin (OXM), released from the endocrine intestinal cells and acting via G-protein coupled receptors (GPCR) either on afferent nerves or directly on ARC neurons, which in turn inhibit expression and release of food-intake stimulating NPY and AgRP, thereby inducing satiety through inhibition of PVN. In contrast, during fasting, the GIT, especially oxyntic mucosa, expresses and releases appetite stimulating (orexigenic) factors such as ghrelin and orexins (OX) -A and OX-B, and cannabinoid CB1 agonist. Ghrelin activates growth-hormone secretagogue receptor (GHS-R) in hypothalamic ARC and stimulates growth hormone (GH) release and in vagal afferents to promote the expression and release of hypothalamic NPY and AgRP stimulating PVN and driving ingestive behaviour. The balance and interaction between anorexigenic (CCK, PYY, OXM) and orexigenic (ghrelin and OX) factors originating from GIT appears to play an important role in short-term regulation of food intake and growth hormone (GH) release. An impairment of this balance may result in disorders of feeding behaviour and weight gain (obesity) or weight loss (cachexia).

Eradication of Helicobacter pylori and gastrin-somatostatin link in duodenal ulcer patients.

Helicobacter pylori (Hp) infection may be associated with duodenal ulcer (DU) and accompanied by increased release of gastrin and deficiency of somatostatin (S-S) but the mechanisms of these changes in DU patients after eradication of Hp have been little studied. Cholecystokinin (CCK) has been implicated in the feedback control of gastric acid secretion in healthy subjects but its contribution to secretory disorders in DU patients has been little examined. This study, therefore, investigated whether CCK participates in the impairment of postprandial gastrin release and gastric acid secretion in active DU patients. Tests were undertaken in 10 DU patients without or with elimination of the action of endogenous CCK using loxiglumide (LOX), a selective CCK-A receptor antagonist, before and 4 wk. after eradication of Hp with triple therapy (omeprazole, amoxycillin and bismuth). In Hp positive DU patients, the postprandial acid secretion (measured by continuous intragastric pH monitoring) was accompanied by a pronounced increment in plasma gastrin with negligible increase of intraluminal release of S-S. The administration of LOX in these patients did not affect significantly the postprandial pH profile and the rise in plasma gastrin. After eradication of Hp the median postprandial intragastric pH increased to about 4.3 (compared to 3.5 before the Hp eradication); the postprandial gastrin concentration was reduced by about 40%, while luminal release of S-S was increased 2 folds. The administration of LOX resulted in significantly greater decrease in median pH (3.1) and higher rise in postprandial plasma gastrin in these patients. Also the postprandial plasma S-S showed a small, but significant decline (by about 25%) as compared to that in placebo treated patients. This study provides evidence that: (1) Hp infection in DU patients is accompanied by enhanced gastrin release and the reduction in luminal release of S-S; (2) The failure of LOX to affect gastric secretion and plasma gastrin DU Hp infected patients could be attributed, at least in part, to the failure of endogenous CCK to control gastric acid secretion via release of S-S; (3) Hp infected patients appear to exhibit a deficiency of S-S release that can be reversed by the eradication of Hp indicating that both peptides may contribute to the acceleration of the ulcer healing following Hp eradication in DU patients; (4) The test with LOX and gastric luminal S-S assay may be useful in identification of Hp positive DU patients with CCK-mediated impaired feedback control of gastric secretion and deficiency of S-S caused by Hp infection.