Ocean warming and acidification modulate energy budget and gill ion regulatory mechanisms in Atlantic cod (Gadus morhua).

Ocean warming and acidification are threatening marine ecosystems. In marine animals, acidification is thought to enhance ion regulatory costs and thereby baseline energy demand, while elevated temperature also increases baseline metabolic rate. Here we investigated standard metabolic rates (SMR) and plasma parameters of Atlantic cod (Gadus morhua) after 3-4 weeks of exposure to ambient and future PCO2 levels (550, 1200 and 2200 µatm) and at two temperatures (10, 18 °C). In vivo branchial ion regulatory costs were studied in isolated, perfused gill preparations. Animals reared at 18 °C responded to increasing CO2 by elevating SMR, in contrast to specimens at 10 °C. Isolated gills at 10 °C and elevated PCO2 (≥1200 µatm) displayed increased soft tissue mass, in parallel to increased gill oxygen demand, indicating an increased fraction of gill in whole animal energy budget. Altered gill size was not found at 18 °C, where a shift in the use of ion regulation mechanisms occurred towards enhanced Na(+)/H(+)-exchange and HCO3 (-) transport at high PCO2 (2200 µatm), paralleled by higher Na(+)/K(+)-ATPase activities. This shift did not affect total gill energy consumption leaving whole animal energy budget unaffected. Higher Na(+)/K(+)-ATPase activities in the warmth might have compensated for enhanced branchial permeability and led to reduced plasma Na(+) and/or Cl(-) concentrations and slightly lowered osmolalities seen at 18 °C and 550 or 2200 µatm PCO2 in vivo. Overall, the gill as a key ion regulation organ seems to be highly effective in supporting the resilience of cod to effects of ocean warming and acidification.

Differential impacts of elevated CO2 and acidosis on the energy budget of gill and liver cells from Atlantic cod, Gadus morhua.

Ocean acidification impacts fish and other marine species through increased seawater PCO2 levels (hypercapnia). Knowledge of the physiological mechanisms mediating effects in various tissues of fish is incomplete. Here we tested the effects of extracellular hypercapnia and acidosis on energy metabolism of gill and liver cells of Atlantic cod. Exposure media mimicked blood conditions in vivo, either during normo- or hypercapnia and at control or acidic extracellular pH (pHe). We determined metabolic rate and energy expenditure for protein biosynthesis, Na(+)/K(+)-ATPase and H(+)-ATPase and considered nutrition status by measurements of metabolic rate and protein biosynthesis in media with and without free amino acids (FAA). Addition of FAA stimulated hepatic but not branchial oxygen consumption. Normo- and hypercapnic acidosis as well as hypercapnia at control pHe depressed metabolic stimulation of hepatocytes. In gill cells, acidosis depressed respiration independent of PCO2 and FAA levels. For both cell types, depressed respiration was not correlated with the same reduction in energy allocated to protein biosynthesis or Na(+)/K(+)-ATPase. Hepatic energy expenditure for protein synthesis and Na(+)/K(+)-ATPase was even elevated at acidic compared to control pHe suggesting increased costs for ion regulation and cellular reorganization. Hypercapnia at control pHe strongly reduced oxygen demand of branchial Na(+)/K(+)-ATPase with a similar trend for H(+)-ATPase. We conclude that extracellular acidosis triggers metabolic depression in gill and metabolically stimulated liver cells. Additionally, hypercapnia itself seems to limit capacities for metabolic usage of amino acids in liver cells while it decreases the use and costs of ion regulatory ATPases in gill cells.

COX-2 dependent inflammation increases spinal Fos expression during rodent postoperative ileus.

BACKGROUND AND AIMS: Cyclooxygenase 2 (COX-2) and prostaglandins (PGs) participate in the pathogenesis of inflammatory postoperative ileus. We sought to determine whether the emerging neuronal modulator COX-2 plays a significant role in primary afferent activation during postoperative ileus using spinal Fos expression as a marker. METHODS: Rats, and COX-2(+/+) and COX-2(-/-) mice underwent simple intestinal manipulation. The effect of intestinal manipulation on Fos immunoreactivity (IR) in the L(5)-S(1) spinal cord, in situ circumference, and postoperative leucocytic infiltrate of the intestinal muscularis was measured. Postoperative PGE(2) production was measured in peritoneal lavage fluid. The dependence of these parameters on COX-2 was studied in pharmacological (DFU, Merck- Frosst, selective COX-2 inhibitor) and genetic (COX-2(-/-) mice) models. RESULTS: Postoperative Fos IR increased 3.7-fold in rats and 2.2-fold in mice. Both muscularis leucocytic infiltrate and the circumference of the muscularis increased significantly in rats and COX-2(+/+) mice postoperatively, indicating dilating ileus. Surgical manipulation markedly increased PGE(2) levels in the peritoneal cavity. DFU pretreatment and the genetic absence of COX-2(-/-) prevented dilating ileus, and leucocytic infiltrate was diminished by 40% with DFU and by 54% in COX-2(-/-) mice. DFU reversed postsurgical intra- abdominal PGE(2) levels to normal. Fos IR after intestinal manipulation was attenuated by approximately 50% in DFU treated rats and in COX-2(-/-) mice. CONCLUSIONS: Postoperatively, small bowel manipulation causes a significant and prolonged increase in spinal Fos expression, suggesting prolonged primary afferent activation. COX-2 plays a key role in this response. This activation of primary afferents may subsequently initiate inhibitory motor reflexes to the gut, contributing to postoperative ileus.

Area postrema lesion alters the effects of peptide YY on 2-DG-stimulated pancreatic exocrine secretion.

Previously we demonstrated that circulating peptide YY (PYY), which inhibits pancreatic exocrine secretion, binds to specific receptors in the area postrema (AP); therefore we have tested the hypothesis that the removal of the AP (APX) will alter the effects of PYY on pancreatic secretion in awake rats. One-month after AP lesion or sham lesion, rats were implanted with pancreatic, biliary, duodenal, and intravenous catheters. After recovery from the surgery, unanesthetized rats were infused with vehicle or PYY (30 pmol/kg/hr or 100 pmol/kg/hr) under basal or 2-deoxy-D-glucose (2-DG) stimulated (75 mg/kg, intravenous bolus) conditions. PYY at 30 pmol/kg/hr inhibited basal pancreatic fluid secretion in sham-operated rats, but not APX rats. PYY at 100 pmol/kg/hr stimulated basal pancreatic protein secretion in sham-operated rats, and this effect was also lost in APX rats. PYY at 30 and 100 pmol/kg/hr inhibited peak 2-DG stimulated protein secretion to a greater extent in APX rats as compared to sham-operated rats (P < 0.05). Since PYY inhibition of basal pancreatic secretion is AP dependent and inhibition of 2-DG stimulated pancreatic secretion is AP independent, we conclude that the 2-DG pathway of pancreatic secretion differs from the pathway responsible for basal secretion, and that APX potentiates the inhibitory effect of PYY on the 2-DG pathway.

PYY inhibits CCK-stimulated pancreatic secretion through the area postrema in unanesthetized rats.

Peptide YY (PYY) inhibits CCK-8-secretin-stimulated pancreatic secretion in vivo. To investigate whether CCK-8-secretin-stimulated pancreatic secretion is mediated through a vago-vagal pathway and whether PYY inhibits this pathway through the area postrema (AP), chronic pancreatic, biliary, and duodenal catheters were implanted in AP-lesioned (APX) or sham-operated rats. The effects of APX on pancreatic secretion stimulated by bethanechol, pancreatic juice diversion (PJD), or CCK-8-secretin, were tested, with and without background PYY infusion, in unanesthetized rats. APX reduced basal pancreatic secretion by 15-20% (P < 0.01). APX had no effect on bethanechol-stimulated secretion and potentiated protein secretion stimulated by PJD (396 vs. 284%) and exogenous CCK-8-secretin. In sham-operated rats, background PYY potently inhibited CCK-8-secretin-stimulated pancreatic fluid (1.8 vs. 48.2%) and protein secretion (3.7 vs. 45.8%) but potentiated fluid (52.9 vs. 43.1%) and protein (132.9 vs. 68.9%) secretion in APX rats. Our findings demonstrate that PYY inhibits CCK-8-secretin-stimulated pancreatic secretion through an AP-dependent mechanism in sham-operated rats. The AP also contributes to basal pancreatic secretion.

Evaluation of gastric emptying and motility in diabetic gastroparesis with magnetic resonance imaging: effects of cisapride.

OBJECTIVE: The motor mechanisms that underlie both slow gastric emptying in diabetic gastroparesis and its acceleration by cisapride are poorly understood. We have recently shown that magnetic resonance imaging (MRI) allows concurrent evaluation of both gastric emptying and regional gastric motility. METHODS: Emptying and motility were measured in eight diabetic patients with previously demonstrated delayed gastric emptying using a rapid MRI technique during oral administration of cisapride and placebo. Studies were performed in a double blind fashion and each patient acted as his own control. Subjects were studied supine for 120 min in a 1.5 Tesla MRI scanner after ingestion of 500 ml of 10% Intralipid. Gastric emptying corrected for the volume of secretions was determined every 15 min using transaxial scans. Each transaxial scan was followed by 120 coronal scans at 1 s intervals. Coronal scans were angled to provide simultaneous imaging of the proximal and distal stomach. MRI studies were also performed in seven diabetic patients with normal emptying who served as disease controls. RESULTS: Emptying was slower in the gastroparetic patients (t(1/2): 124 +/- 10 min) compared to patients with normal emptying (81 +/- 9 min, p < 0.05). Cisapride accelerated gastric emptying (74 +/- 5 vs 124 +/- 10 min) in patients with gastroparesis. The contraction amplitudes in the proximal stomach of gastroparetic patients were increased during cisapride treatment (17.2% +/- 1.8% vs 13.2% +/- 0.6%; p < 0.02), whereas antral contraction frequency, amplitude, and velocity were unchanged. CONCLUSIONS: We conclude that cisapride-induced acceleration of liquid gastric emptying in diabetic gastroparesis does not appear to result from changes in antral contractility, but may be related to changes in proximal gastric tone or gastric outlet resistance.

Pneumatosis intestinalis complicating C. difficile pseudomembranous colitis.

Pneumatosis intestinalis (PI) is characterized by multiple gas-filled cysts or linear gas within the bowel wall. PI may be idiopathic (15%) or secondary (85%) to a variety of disorders. We report here the first otherwise healthy adult with C. difficile infection complicated by PI and review the possible mechanisms of this previously unrecognized complication of pseudomembranous colitis. With treatment of the underlying infection, the PI resolved within 6 days of presentation.

Oral immunization with urease and Escherichia coli heat-labile enterotoxin is safe and immunogenic in Helicobacter pylori-infected adults.

BACKGROUND & AIMS: Oral immunization with Helicobacter pylori urease can cure Helicobacter infection in animals. As a step toward therapeutic immunization in humans, the safety and immunogenicity of oral immunization with recombinant H. pylori urease were tested in H. pylori-infected adults. METHODS: Twenty-six H. pylori-infected volunteers were randomized in a double-blind study to four weekly oral doses of 180, 60, or 20 mg of urease with 5 microg heat-labile enterotoxin of Escherichia coli (LT), LT alone, or placebo. Side effects and immune responses were evaluated weekly after immunization, and gastric biopsy specimens were obtained after 1 month and 6 months for histology and quantitative cultures. RESULTS: Diarrhea was noted in 16 of 24 (66%) of the volunteers who completed the study. Antiurease serum immunoglobulin A titers increased 1. 58-fold +/- 0.37-fold and 3.66-fold +/- 1.5-fold (mean +/- SEM) after immunization with 60 and 180 mg urease, respectively, whereas no change occurred in the placebo +/- LT groups (P = 0.005). Circulating antiurease immunoglobulin A-producing cells increased in volunteers exposed to urease compared with placebo (38.9 +/- 13. 6/10(6) vs. 5.4 +/- 3.1; P = 0.018). Eradication of H. pylori infection was not observed, but urease immunization induced a significant decrease in gastric H. pylori density. CONCLUSIONS: H. pylori urease with LT is well tolerated and immunogenic in H. pylori-infected individuals. An improved vaccine formulation may induce curative immunity.

Effect of lintitript, a new CCK-A receptor antagonist, on gastric emptying of a solid-liquid meal in humans.

The role of cholecystokinin (CCK) in the regulation of gastric emptying of physiological meals containing solids and liquids in humans remains controversial. We studied the role of endogenous CCK in the emptying of a solid/liquid meal administering the new, highly specific and potent CCK-A receptor antagonist lintitript. Gastric emptying was assessed in nine healthy male volunteers using a randomized, double blind, two-period crossover design with oral lintitript (15 mg 1 h prior to meal intake) or placebo on two different days. After ingestion of a pancake (570 kcal) labelled with 500 microCi of 99mTc-sulfur colloid and 500 ml 10% dextrose containing 80 microCi. 111In-DTPA, subjects were studied in a sitting position, using a dual-headed gamma camera. Plasma CCK and pancreatic polypeptide (PP) were measured by a specific RIA. Lintitript distinctly accelerated gastric emptying of solids, while gastric emptying of liquids was not significantly altered. The lag period was shortened by 20% (P<0.05), AUC and half emptying time of solid emptying were lowered by 12% and 13%, respectively (P<0.03). Lintitript markedly increased postprandial plasma CCK release (P<0.001) while distinctly reducing postprandial PP levels (P<0.01) as compared to placebo. These data provide further evidence for a significant role of CCK in the regulation of gastric emptying of solids. The study demonstrates for the first time the marked gastrokinetic properties of the new CCK-A receptor antagonist lintitript in humans.

Gastric emptying and motility: assessment with MR imaging--preliminary observations.

PURPOSE: To evaluate a magnetic resonance (MR) imaging method for simultaneous assessment of gastric emptying and motility. MATERIALS AND METHODS: Gastric emptying and motility were measured in nine volunteers after ingestion of a liquid meal. A specially designed MR imaging protocol was used that allowed simultaneous assessment of gastric emptying (spatial resolution, 1.5 mm; corrected for gastric secretion volume) and gastric motility (temporal resolution, 1.2 seconds; spatial resolution, 3.1 mm). To evaluate the ability to detect small changes in gastric motor activity with findings from this method, the influence of a prokinetic agent (loxiglumide) on gastric emptying and motility was tested in five volunteers. RESULTS: Each contraction could be individually visualized at MR imaging. Administration of loxiglumide resulted in decreased gastric half-emptying time (mean +/- 1 standard error of the mean, 88.1 minutes +/- 6.3 for the placebo and 39.1 minutes +/- 6.7 for loxiglumide) and increased gastric motility (contraction frequency, 2.26 contractions per minute +/- 0.15 for the placebo and 3.04 per minute +/- 0.04 for loxiglumide). CONCLUSION: MR imaging makes it feasible to study gastric emptying and gastric motility and to determine the influence of drugs on gastric motor activity.

Role of cholecystokinin in the regulation of liquid gastric emptying and gastric motility in humans: studies with the CCK antagonist loxiglumide.

BACKGROUND: Exogenous cholecystokinin (CCK) inhibits antral motility and slows gastric emptying (GE) but the effect of endogenous CCK on the gastric motor mechanisms responsible for GE remains unclear. METHODS: The effect of the CCK-A antagonist loxiglumide (LOX) on GE and motility was studied using magnetic resonance imaging in six healthy volunteers after ingestion of 500 ml Intralipid 10% (550 kcal). Subjects were studied in the supine position on two occasions during intravenous infusion of LOX (66 mumol/kg/h for 10 min followed by 22 mumol/kg/h) or placebo. GE was determined every 15 minutes using transaxial abdominal scans and motility was studied by means of 120 coronal scans, 1.2 seconds apart. For each coronal image the proximal and distal (antral) diameters were measured at a fixed point in the stomach to determine contraction frequency (ACF) and amplitude (AMP). RESULTS: GE was faster during LOX infusion than placebo (t1/2 31 (22) versus 115 (67) minutes, p < 0.03). There was little variation in the diameter of the proximal stomach with either LOX or placebo. In the distal stomach marked contractile activity was observed during LOX (ACF 2.9 (0.2) versus 1.5 (2.9) during placebo, p < 0.01). AMP also increased during LOX compared with placebo (56 (22)% versus 27 (16)%, p < 0.001). CONCLUSION: The increases in antral motility are likely to contribute to the acceleration of GE and suggest that CCK may regulate GE by acting on the distal stomach although an effect on the proximal stomach cannot be excluded.

Role of lipase in the regulation of upper gastrointestinal function in humans.

The role of lipase in the regulation of upper gastrointestinal function is poorly understood. We studied the effect of orlistat, a new, potent, and highly specific lipase inhibitor, on gastric emptying, cholecystokinin (CCK) release, and pancreaticobiliary secretion. Three groups of studies were performed in nine healthy volunteers, using the double-indicator technique with a triple-lumen duodenal tube, polyethylene glycol 4000 as a duodenal perfusion marker, and 99mTc-diethylenetriamine pentaacetic acid as a meal marker. Gastric emptying, pancreaticobiliary output, and postprandial plasma CCK levels were measured after ingestion of the following isocaloric 500-ml liquid meals with or without 200 mg orlistat: 1) a pure fat meal (10% Intralipid), 2) a meal containing free fatty acids, or 3) an albumin-glucose meal. All experiments were performed in a randomized, placebo-controlled, crossover design. Orlistat markedly inhibited lipase activity in all three experiments. Orlistat given with the fat meal reduced CCK release and output of lipase, trypsin, and bilirubin and accelerated the rate of gastric emptying (P < 0.05). After ingestion of the free fatty acid or albumin-glucose meal, orlistat had no significant effect on any of these parameters. We conclude that lipase plays an important, nutrient-specific role in the regulation of gastric emptying and pancreaticobiliary secretion after ingestion of fatty meals in humans.

Regulation of gastric and pancreatic lipase secretion by CCK and cholinergic mechanisms in humans.

Gastric lipase (HGL) contributes significantly to fat digestion. However, little is known about its neurohormonal regulation in humans. We studied the role of CCK and cholinergic mechanisms in the postprandial regulation of HGL and pancreatic lipase (HPL) secretion in six healthy subjects. Gastric emptying of a mixed meal and outputs of HGL, pepsin, acid, and HPL were determined with a double-indicator technique. Three experiments were performed in random order: intravenous infusion of 1) placebo, 2) low-dose atropine (5 micrograms.kg-.h-1), and 3) the CCK-A receptor antagonist loxiglumide (22 mumol.kg-.h-1). Atropine decreased postprandial outputs of HGL, pepsin, gastric acid, and HPL (P < 0.03) while slowing gastric emptying (P < 0.05). Loxiglumide markedly increased the secretion of HGL, pepsin, and acid while distinctly reducing HPL outputs and accelerating gastric emptying (P < 0.03). Plasma CCK and gastrin levels increased during loxiglumide infusion (P < 0.03). Atropine enhanced gastrin but not CCK release. Postprandial HGL, pepsin, and acid secretion are under positive cholinergic but negative CCK control, whereas HPL is stimulated by cholinergic and CCK mechanisms. We conclude that CCK and cholinergic mechanisms have an important role in the coordination of HGL and HPL secretion to optimize digestion of dietary lipids in humans.

Role of cholecystokinin as a regulator of solid and liquid gastric emptying in humans.

The role of endogenous cholecystokinin (CCK) in the regulation of gastric emptying remains controversial. We therefore studied the effect of the CCK-A receptor antagonist loxiglumide on gastric emptying of a high-caloric solid-liquid meal in humans. Gastric emptying was assessed in eight volunteers using intravenous loxiglumide or placebo in a randomized double-blind order. Subjects were studied by a dual-headed gamma camera after ingestion of a pancake (570 kcal) labeled with 99mTc-sulfur colloid and 500 ml 10% glucose containing 111In-diethylenetriamine pentaacetic acid. Plasma CCK was measured by a specific radioimmunoassay. Loxiglumide markedly accelerated gastric emptying of both phases of the meal. The lag period was shortened by 26% (P < 0.03); the area under the emptying curve and half-emptying time of solid emptying were lowered by 19 and 24% (P < 0.02) and of liquid emptying by 18 and 24% (P < 0.04), respectively. Plasma CCK levels were higher during infusion of loxiglumide compared with placebo (P < 0.02). These data demonstrate that post-prandially released CCK is a major regulator of gastric emptying of physiological meals containing both solid and liquid components.

Role of antrum in regulation of pancreaticobiliary secretion in humans.

Little is known about the role of the gastric phase in the postprandial pancreaticobiliary response. We evaluated the effect of antral distension on pancreatic, biliary, and gastric secretions and on the release of cholecystokinin (CCK), gastrin, and pancreatic polypeptide in five healthy volunteers. Studies were performed using a duodenal tube with an inflatable balloon in the antrum and a separate gastric tube. Outputs were compared with responses to a maximal CCK stimulus (caerulein), and the role of cholinergic mechanisms was investigated using atropine. Graded antral distension by 50-, 200-, and 350-ml balloon volumes and constant antral distension by 350 ml elicited a marked stimulation of pancreaticobiliary secretions. Mean lipase outputs amounted to 52-60%, and mean bilirubin outputs reached 14-22% of maximal. Atropine completely abolished pancreaticobiliary responses to antral distension. Antral distension did not affect bicarbonate and gastric secretions. Plasma pancreatic polypeptide levels increased markedly during antral distension, and this effect was completely suppressed by atropine. There were no changes in circulating gastrin and CCK. These data demonstrate that antral distension with already small volumes of 50 ml elicits a hitherto unknown potent stimulatory effect, indicating a major role of the antrum in the postprandial pancreaticobiliary response in humans, which is mediated by cholinergic mechanisms.

[Epidemiology and risk factors of gastroduodenal ulcer]. / Epidemiologie und Risikofaktoren der gastroduodenalen Ulcuskrankheit.

Today, the lifetime prevalence of peptic ulcer disease is in industrialized countries approximately 5 to 10%. There has been a substantial decline in peptic ulcer incidence and mortality over the last forty years. The two principal, independent risk factors of gastric and duodenal ulcer disease are a preexisting Helicobacter pylori infection and the regular intake of nonsteroidal anti-inflammatory drugs (NSAID). Several characteristics of H. pylori infection which contribute to the final event of ulceration have been identified. Bacterial virulence factors and the severity of gastritis seem to play an important role. It remains unclear, whether the degree of gastritis is due to host factors or to the pathogen. NSAID-induced peptic ulcers are often asymptomatic and therefore diagnosis is not being made until complications arise. NSAID-ulcers often bleed. NSAID ulceration can induced develop already after a short course of treatment. The combination of NSAIDs with anticoagulants or corticosteroids potentiates the ulcer risk. Age, diet, smoking and psychological factors have a rather permissive and optional influence on peptic ulcer pathogenesis.

[Functional dyspepsia: approaches to Helicobacter pylori eradication therapy]. / Funktionelle Dyspepsie: Ansätze für eine Helicobacter pylori-Eradikationstherapie.

At the present, Helicobacter-associated gastritis is not considered to be an important cause of dyspeptic symptoms. Therefore, patients with dyspeptic symptoms and proven Helicobacter-gastritis are diagnosed as having functional dyspepsia, provided that Helicobacter-associated lesions like ulcers or malignancies are absent. It is controversial whether or not to treat a patient with functional dyspepsia with Helicobacter gastritis. Conclusive controlled clinical trials are lacking. If it is assumed in a given patient, that Helicobacter could be responsible for the complaints (an assumption which can never be proven and only suspected when the patient remains asymptomatic during longterm follow-up after cure of the infection) and if the patient has not responded to a standard treatment (antisecretory or prokinetic agents), we recommend Helicobacter therapy. Presently, in spring 1995, the following treatment is, in our view, the best choice during seven (to ten) days: The patient takes 20 mg omeprazol in the morning, 250 mg clarithromycin in the morning and in the evening and 500 mg metronidazole in the morning and in the evening.