Jan W. Konturek

Gastric electrical stimulation for medically refractory gastroparesis

BACKGROUND & AIMS This study investigated the efficacy of gastric electrical stimulation for the treatment of symptomatic gastroparesis unresponsive to standard medical therapy. METHODS Thirty-three patients with chronic gastroparesis (17 diabetic and 16 idiopathic) received continuous high-frequency/low-energy gastric electrical stimulation via electrodes in the muscle wall of the antrum connected to a neurostimulator in an abdominal wall pocket. After implantation, patients were randomized in a double-blind crossover design to stimulation ON or OFF for 1-month periods. The blind was then broken, and all patients were programmed to stimulation ON and evaluated at 6 and 12 months. Outcome measures were vomiting frequency, preference for ON or OFF, upper gastrointestinal tract symptoms, quality of life, gastric emptying, and adverse events. RESULTS In the double-blind portion of the study, self-reported vomiting frequency was significantly reduced in the ON vs. OFF period (P < 0.05) and this symptomatic improvement was consistent with the significant patient preference (P < 0.05) for the ON vs. OFF period determined before breaking the blind. In the unblinded portion of the study, vomiting frequency decreased significantly (P < 0.05) at 6 and 12 months. Scores for symptom severity and quality of life significantly improved (P < 0.05) at 6 and 12 months, whereas gastric emptying was only modestly accelerated. Five patients had their gastric electrical stimulation system explanted or revised because of infection or other complications. CONCLUSIONS High-frequency/low-energy gastric electrical stimulation significantly decreased vomiting frequency and gastrointestinal symptoms and improved quality of life in patients with severe gastroparesis.

Gastric electrical stimulation in intractable symptomatic gastroparesis.

Background: The treatment of gastroparesis remains unsatisfactory despite prokinetic and anti-emetic drugs. Gastric electrical stimulation has been proposed as a therapeutic option. We have assessed the effect of gastric electrical stimulation on symptoms, medical treatment, body weight and gastric emptying in patients with intractable symptomatic gastroparesis in a non-placebo-controlled study. Methods: In this multicenter study, 38 highly symptomatic patients with drug-refractory gastroparesis were enrolled. Patients first received temporary electrical stimulation using percutaneous electrodes. The 33 responders to temporary stimulation then underwent surgical implantation of a permanent stimulator. Severity of vomiting and nausea was assessed before and after stimulation. Patients were reassessed 3, 6, and 12 months after permanent implantation. Results: With stimulation, 35/38 patients (97%) experienced >80% reduction in vomiting and nausea. This effect persisted throughout the observation period (2.9–15.6 months, 341 patient-months). Gastric emptying did not initially change, but improved in most patients at 12 months. At 1 year, the average weight gain was 5.5% and 9/14 patients initially receiving enteral or parenteral nutrition were able to discontinue it. Conclusion: Electrical stimulation of the stomach has an immediate and potent anti-emetic effect. It offers a safe and effective alternative for patients with intractable symptomatic gastroparesis.

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.

Epidermal growth factor in protection, repair, and healing of gastroduodenal mucosa

Gastrointestinal mucosa is one of the most rapidly proliferating tissues in the body and the alteration in the balance between cell regeneration and cell loss may lead to mucosal lesions and ulcerations. Mucosal growth is under the influence of various growth factors, among which epidermal growth factor (EGF) and polyamines seem to play a crucial role. EGF is produced in large quantities in salivary and pancreatic glands and secreted mainly into the gut lumen and partly released into the bloodstream from where it is cleared by the kidneys and excreted into the urine as urogastrone. The physiological role of EGF is still under active investigations but it appears that EGF may be required for the maintenance of mucosal integrity and healing of mucosal defects due to its accumulation in the lesion area and local stimulation of healing processes. The mechanism of protective and ulcer healing effects of EGF involves the activation of ornithine decarboxylase (ODC), the key enzyme in the biosynthesis of polyamines, which play a crucial role in the growth-promoting action of EGF. Substances that affect the generation and/or catabolism of polyamines affect the gastroprotective and ulcer healing effect of EGF but not that of exogenous polyamines. Mucosal generation of protective prostaglandins appears to be essential mainly for the gastroprotective effects of EGF but seem to be of little importance in the healing effects of EGF on acute and chronic gastroduodenal ulcerations.

Effects of Cyclic Hexapeptide Analog of Somatostatin on Pancreatic Secretion in Dogs

Abstract The effects of a cyclic hexapeptide analog of somatostatin, [cyclo(Pro-Phe-D-Trp-Lys-Thr-Phe)] (cyclo-SS), administered intravenously (iv) or instilled into the duodenum (id) on the pancreatic response to endogenous (meal and duodenal acidification) and exogenous (secretin, CCK) stimulants were compared in five dogs with esophageal, gastric, and pancreatic fistulae. Cyclo-SS given iv in graded doses against a constant background stimulation with secretin caused a similar and dose-dependent inhibition of pancreatic HCO3 and protein secretion being about twice as potent as somatostatin-14 (SS-14). Cyclo-SS, whether applied topically to the duodenal mucosa in a dose of 1 μg/kg or given iv at a dose of 0.5 μg/kg-hr, resulted in a similar inhibition of pancreatic secretion induced by feeding a meat meal, sham-feeding, duodenal acidification, or infusion of secretin or CCK. The inhibition of pancreatic secretion by cyclo-SS was due in part to direct inhibitory action on the exocrine pancreas as well as to the suppression of the release of secretin, insulin, and pancreatic polypeptide. It is concluded that cyclo-SS is a more potent inhibitor of pancreatic secretion than SS-14 and that it is active when administered both parenterally and intraduodenally.

Growth markers in the human gastric mucosa during adaptation to continued aspirin administration.

The mechanism of gastric mucosal adaptation to continued aspirin (ASA) administration is unknown. We have investigated growth and proliferation markers in healthy subjects under prolonged ASA treatment. In eight healthy volunteers, ASA treatment (2 g/day) was continued for 14 days. Endoscopy was performed before medication; at days 3, 7, and 14 of ASA treatment; and at days 16 and 18 (2 and 4 days, respectively, after medication was ceased). Gastric biopsies from oxyntic and antral mucosa were studied by histology and by histochemistry for proliferating cell nuclear antigen (PCNA), epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and epidermal growth factor receptor (EGFr). ASA treatment did not change the expression of EGF and EGFr significantly. The PCNA index showed local inconsistent variations. However, increased TGF-alpha expression after ASA was noted, particularly in hyperplastic surface epithelium. Edema and teleangiectases were common in gastric mucosa after ASA. An increasing incidence of foveolar hyperplasia was also noted in the antral mucosa. Healthy subjects on prolonged ASA treatment gradually develop parameters of chronic reactive gastritis accompanied by increased TGF-alpha expression in gastric surface epithelial cells, especially in hyperplastic areas.

Effects of Sucralfate on Growth Factor Availability

The maintenance of gastric mucosal integrity under an adverse environment of luminal contents depends on the delicate balance of numerous factors that control the mucosal defense lines such as mucus-alkaline secretion, mucosal hydrophobicity, rich mucosal blood flow, maintenance of mucosal sulfhydryls, rapid restitution of epithelial cells, proliferation of mucosal cells, and tissue repair.

Valosin Stimulates Gastric and Exocrine Pancreatic Secretion and Inhibits Fasting Small Intestinal Myoelectric Activity in the Dog

Valosin, a novel 25-amino acid gastrointestinal peptide with N-terminal valine and C-terminal tyrosine, has recently been isolated from porcine upper gut extracts. Its physiologic role is unknown and it does not belong to one of the structurally related gut peptide families. Assuming that valosin may influence gastrointestinal functions, we investigated the effect of high-performance liquid chromatography-pure valosin on gastric and exocrine pancreatic secretion and on the intestinal myoelectric activity in conscious dogs. Intravenous injection of valosin (0.125-1 microgram/kg) dose-dependently increased gastric acid secretion 80-fold over basal, corresponding to 18% of the maximal pentagastrin-induced effect. Pepsin output increased 10-fold over basal (30% of the pentagastrin-stimulated secretion). Half-maximal stimulation by pentagastrin could be further increased dose-dependently by simultaneous administration of valosin. Pancreatic bicarbonate secretion was stimulated 11-fold over basal at 1.0 microgram/kg, reaching about 6% of the secretin-induced maximal output, whereas protein secretion increased 12-fold over basal, corresponding to about 55% of the cholecystokinin-induced maximal output. In fasted dogs, spontaneously occurring migrating myoelectric complexes were substantially delayed during infusion of valosin at a dose of 0.2 microgram/kg. These experiments indicate that valosin may represent a novel member of the regulatory gastrointestinal peptides.

Diffuse esophageal spasm: a malfunction that involves nitric oxide?

OBJECTIVE As recently suggested, nitric oxide (NO) may play an important role in the regulation of esophageal motility, being partly responsible for the latency period and latency gradient between the onset of a swallow and contractions of esophageal circular smooth muscles. Diffuse esophageal spasm appears to be a classical example in which the mechanisms normally responsible for the physiologic timing of the contractions occurring in the esophageal body after swallowing are disturbed. METHODS Five patients (one male and four female; age, 18-48 years) with symptomatic esophageal spasm were give glyceryl trinitrate (GTN) intravenously in gradually increasing doses or L-arginine on two separate occasions and underwent manometric measurements of esophageal motility after wet swallows, using a multilumen perfused catheter system (Synetics Medical, Stockholm, Sweden). The amplitude, duration, and propagation of the contractions and the latency period were analyzed, using specially designed software. Additionally, during the GTN infusion period arterial blood pressure was measured every 5 min, RESULTS GTN infusion given at a dose of 100 to 200 micrograms/kg-h intravenously caused the occurrence of and a dose-dependent elongation of the latency period after swallowing. The mean amplitude of the contractions did not show any significant alterations, whereas the mean duration of the contractions decreased significantly, from 11.2 +/- 4.8 sec to 5.4 +/- 0.8 sec. These effects were accompanied by significant alleviation of symptoms during swallowing. Interestingly, no adverse side effects such as headache or flush were observed at any dose of GTN. The blood pressure did not show any changes during the studies in any of the five patients. Administration of L-arginine (300 mg/kg-h intravenously) did not cause any significant alterations of motility pattern or alleviation of dysphagia. CONCLUSIONS 1) NO may play an important role in the control of human esophageal motility, being involved in the mechanisms responsible for the timing of propulsive contractions in the body after swallowing; 2) GTN may to be of benefit in the treatment of diffuse esophageal spasm in symptomatic patients; and 3) patients with diffuse esophageal spasm may have a malfunction in endogenous NO synthesis and/or degradation.

Cholecystokinin in the control of gastric acid secretion in humans.

This study was designed to determine the role of cholecystokinin in the control gastric acid secretion in men using loxiglumide, a specific cholecystokinin receptor blocker. Three groups of healthy subjects (A, B, and C) were used; group A--for studies with postprandial gastric secretion, group B--for studies with exogenous gastric secretagogues and group C--for 12 hour intragastric pH-metry. Cephalic phase stimulated by modified sham feeding in group A subjects increased gastric acid secretion to about 50% of pentagastrin maximum and the treatment with loxiglumide in a standard dose (20 mumol/kg iv loading dose plus infusion of 20 mumol/kg/h afterwards) failed to affect this secretion. Gastric acid response to a 5% peptone meal instilled intragastrically greatly enhanced gastric acid secretion and plasma gastrin concentration but the addition of loxiglumide in the standard dose resulted in further increase in both gastric acid and plasma gastrin responses to peptone meal. Infusion of caerulein in gradually increasing doses (15-120 pmol/kg/h) and gastrin releasing peptide (25-200 pmol/kg/h) resulted in a dose dependent stimulation of gastric acid secretion reaching about 35% and 25% of maximum attained with pentagastrin. When loxiglumide was added in a standard dose, the acid responses to caerulein and gastrin releasing peptide were further increased two to three fold attaining the peak reaching, respectively, about 100% and 50% of pentagastrin maximum. In group C subjects, 12 hour pH-metry revealed the usual increase in gastric pH after each meal in tests with placebo. Loxiglumide (1200 mg tablets tid, po) resulted in significantly lower pH after each meal and this was accompanied by significantly higher gastrin responses than in placebo tests. We conclude that cholecystokinin released by peptone meal, ordinary meals or gastrin releasing peptide exerts a potent inhibitory influence on gastric acid secretion and gastrin release in men and this inhibition involves subtype A cholecystokinin receptors.