Prostaglandin E2 in jejunal fluids and its potential diagnostic value for selecting patients with indomethacin-sensitive diarrhoea

Effects of Seal Oil on Meal-Induced Symptoms and Gastric Accommodation in Patients with Subjective Food Hypersensitivity: A Pilot Study

Background

Food hypersensitivity is a prevalent condition with poorly characterized underlying mechanisms. In the present pilot study we investigated effects of seal oil and soy oil on meal-induced symptoms and gastric accommodation in patients with subjective food hypersensitivity (FH). Single dose experiment: On three consecutive days, 10 mL of seal oil, soy oil, or saline were randomly administered into the duodenum of 10 patients with subjective FH and 10 healthy volunteers through a nasoduodenal feeding tube 10-20 minutes before the ingestion of a test meal. Short-term treatment study: 24 patients with subjective FH were randomly allocated to 10 days’ treatment with either 10 mL of seal or soy oil, self-administrated through an indwelling nasoduodenal feeding tube, 3 times daily. In both experiments meal-induced abdominal symptoms and gastric accommodation were measured by visual analogue scales and external ultrasound respectively.

Results

Symptoms and gastric accommodation were not significantly influenced by single doses of seal or soy oil. When given daily for 10 days, seal oil, but not soy oil, reduced total symptom scores significantly ( P = 0.03). The symptomatic improvement was not associated with improvements in gastric accommodation.

Conclusion

Daily administration of seal oil may benefit patients with subjective FH. The beneficial effect of seal oil in patients with subjective FH can not be ascribed to improved gastric accommodation.

Role of immunologic factors and cyclooxygenase 2 in persistent postinfective enteric muscle dysfunction in mice

BACKGROUND & AIMS

Chronic abdominal symptoms develop in some patients after acute enteric infection. This study examined mechanisms underlying smooth muscle hypercontractility that persists after acute infection in mice.

METHODS

Euthymic and athymic National Institutes of Health (NIH) Swiss mice were infected with Trichinella spiralis and studied 4 weeks postinfection (PI). Isometric tension was assessed in longitudinal muscle. Cytokine and cyclooxygenase (COX)-2 messenger RNA was determined in the muscularis externa by reverse-transcription polymerase chain reaction. COX-2 protein was identified by immunohistochemistry and prostaglandin E(2) was measured by enzymatic immunoassay. Studies were performed in euthymic and athymic NIH Swiss mice 28 days PI and in the presence or absence of treatment with corticosteroid or COX inhibitors.

RESULTS

Muscle hypercontractility was evident in euthymic mice but was attenuated in athymic mice or in steroid-treated euthymic mice 28 days PI. Expression of Th2 cytokines interleukins 4, 5, and 13 was increased during the acute infection but not thereafter. COX-2 was localized to muscle and its enzymatic activity remained significantly increased in the muscle on day 28 PI. Selective COX-2 inhibition in vitro reduced the sustained increase in tension generation.

CONCLUSIONS

These findings show that COX-2 activation in resident cells of the muscularis externa contributes to the muscle hypercontractility that persists after infection.

A new reliable chemiluminescence immunoassay (CLIA) for prostaglandin E2 using enhanced luminol as substrate

A sensitive and reliable chemiluminescence immunoassay suitable for the quantitative determination of prostaglandin E2 (PGE2) has been developed using 96 well microtiter plates (MTP). The assay is based on a competitive reaction between a highly specific monoclonal anti-PGE2 antibody (mouse), free antigen and solid phase bound antigen. The MTP was first coated with a bovine serum albumin (BSA)-PGE2 conjugate. Then, after preincubating, the anti-PGE2 antibody (Ab) and the analyte were added. The remaining amount of free antibody was captured by the solid phase bound BSA-PGE2 conjugate. The monoclonal antibody captured on the MTP was determined using biotinylated anti-mouse-Ab and a complex of avidin and biotin-labelled horseradish peroxidase (HRP). Substrate for HRP was the cyclic diacyl hydrazide compound luminol, enhanced by p-iodophenol. Photons emitted during the reaction were measured using a photomultiplier tube. The assay has been validated with assay buffer and human plasma over a concentration range of 10-50,000 pg/ml. The lower limit of quantification is 100 pg/ml (2 pg/well) and 150 pg/ml (3 pg/well) for buffer and plasma, respectively. The intra-day coefficients of variation (CV) for the range of 100-50,000 pg/ml are 3.2-8.9% (buffer) and 4.2-17.7% (plasma) and inter-day CV are 2.9-19.8% (buffer) and 3.6-21.2% (plasma). The method can be used for quantification of PGE2 in biological fluids like plasma and suction blister fluid.

Mediators of inflammation in chronic inflammatory bowel disease

A distinguishing feature of inflammatory bowel disease (IBD) is its apparently spontaneous, chronic relapsing course. Despite extensive research over several decades the etiology of IBD remains unknown, but evidence has accumulated to suggest that the mucosal inflammatory response may be caused by (i) a defective mucosal barrier function resulting in an abnormally increased exposure to luminal antigens and toxins, (ii) an appropriate immunologic response to an unusual infection, antigen or toxin, or (iii) an inappropriate immunological response to ubiquitous antigens or stimuli. In recent years, the identification of established and potential mediators of inflammation has expanded to include eicosanoids, platelet activating factor, biogenic amines, kinins, complement-derived peptides, chemotactic peptides, cytokines, neuropeptides, and reactive metabolites of oxygen and nitrogen. Thus, the study of the inflammatory process has become ever more complex. Until the predisposing and trigger factors have been identified the achievement of a more rational and effective approach to therapy in IBD relies on interruption of the mechanisms responsible for excess mediator formation. As summarized in this review on the role of soluble mediators of inflammation, several Danish gastroenterologists have been profoundly engaged in basic and clinical research in the past 25 years to place some pieces of the confusing puzzle of IBD.

Selective blockade of leukotriene production by a single dose of the FPL 64170XX 0.5% enema in active ulcerative colitis

5-Lipoxygenase products of arachidonic acid metabolism are thought to play a central role in the secondary amplification of the inflammatory response of several inflammatory diseases, including ulcerative colitis. FPL 64170XX is a selective inhibitor of the enzyme 5-lipoxygenase. Concentrations of leukotriene B4 and prostaglanding E2 in rectal dialysis fluid from 23 males with clinically and sigmoidoscopically active, distally located ulcerative colitis were measured by radioimmunoassays in a double-blind, placebo-controlled, parallel design study before and after rectal administration of an enema containing 0.5% of FPL 64170XX. Repeated measures analysis of leukotriene B4, after adjusting for baseline, showed a significant treatment effect (P = 0.0014). The concentration of leukotriene B4 from rectal dialysates in patients receiving the active drug dropped to 15% (95% confidence interval 5-40%) of the placebo level in the second dialysis following administration of FPL 64170XX 0.5%. By contrast, prostaglanding E2 concentrations doubled (P = 0.0068) in patients receiving FPL 64170XX 0.5% with no change in the placebo group. These findings demonstrate that a single dose of FPL 64170XX 0.5% enema selectively blocks the generation of the 5-lipoxygenase product, leukotriene B4, to a mean of 85% in the target tissue of inflammation. Topical administration of this new leukotriene synthesis inhibitor may prove to be a clinically useful approach to the treatment of active, distally located ulcerative colitis.

Muscarinic M1 receptor inhibition reduces gastroduodenal bicarbonate secretion and promotes gastric prostaglandin E2 synthesis in healthy volunteers

The selective muscarinic M1 receptor antagonist, pirenzepine, considerably stimulates duodenal mucosal bicarbonate secretion in the rat and increases gastric luminal release of prostaglandin E2 (PGE2) in humans. This study, therefore, looked at the effect of pirenzepine on bicarbonate secretion and luminal output of PGE2 into the stomach and the duodenum of nine healthy volunteers using a new technique permitting simultaneous measurements. In the stomach modified sham feeding increased bicarbonate secretion from 382 (62) mumol/h (mean (SEM)) to 959 (224) mumol/h (p < 0.02). In the duodenum modified sham feeding and acid exposure (HCl 0.1 M; 20 ml; 5 min) of the duodenal bulb increased mucosal bicarbonate secretion from 191 (14) mumol/cm x h to 266 (27) mumol/cm x h (p < 0.02) and 634 (157) mumol/cm x h (p < 0.01), respectively. Pirenzepine (10 mg/h intravenously) reduced basal and vagally stimulated gastric and basal duodenal bicarbonate secretion by about 50% (p < 0.03). In the stomach, but not the duodenum, basal and vagally stimulated PGE2 output increased significantly (p < 0.05) in response to pirenzepine. In conclusion, human gastroduodenal mucosal bicarbonate secretion is regulated by a pirenzepine sensitive mechanism, which is probably cholinergic. The rise in gastric PGE2 output seen in response to M1 receptor inhibition by pirenzepine suggests the existence of a feed back loop secondary to the decrease seen in bicarbonate secretion.

Blockade of leukotriene production by a single oral dose of MK-0591 in active ulcerative colitis

BACKGROUND

5-Lipoxygenase products of arachidonic acid metabolism are thought to play a central role in the secondary amplification of the inflammatory response in a number of human inflammatory diseases, such as ulcerative colitis. MK-0591 (3-(1((4-chlorophenyl)methyl)-3((1,1-dimethyl-ethyl)thio)-5(quinolin+ ++-2ylmethyl-oxy)-1H-indol-2yl)-2,2-dimethyl-propanoate) exerts its effect by binding to the 5-lipoxygenase activating protein, thereby inhibiting the translocation and activation of 5-lipoxygenase.

METHODS

Concentrations of leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) in rectal dialysis fluid, ex vivo biosynthesis of LTB4 in whole blood, and urinary excretion of leukotriene E4 (LTE4) from 16 patients with mild to moderately active distally located ulcerative colitis were measured by use of radioimmunoassays in a double-blind, placebo-controlled parallel-design study before and after oral administration of a 250 mg dose of MK-0591 or placebo.

RESULTS

The mean LTB4 concentration in rectal dialysis fluid was lowered after MK-0591 by > 90% (p < 0.05) from 4 to 8 hours, with a maximum inhibition of 97.5% +/- 3.4% (mean +/- SD) at 20 to 24 hours after dosing, whereas PGE2 was unchanged. In whole blood, MK-0591 decreased ex vivo biosynthesis of LTB4 (p < 0.01), with a maximum inhibition of 96.4% +/- 2.1% at 4 hours after dosing. Urinary excretion of LTE4 was reduced by more than 85% (p < 0.001) from 4 to 48 hours. No adverse events were observed.

CONCLUSION

These findings show that a single oral 250 mg dose of MK-0591 results in nearly complete blockade of systemic leukotriene production and LTB4 formation in the target tissue of inflammation (the rectum). Controlled multiple-dose trials to assess the clinical efficacy of this novel 5-lipoxygenase-activating protein inhibitor seem to be worthwhile.

Significance of nitric oxide in the stimulation of intestinal fluid absorption in the rat jejunum in vivo

1. The effects of inhibiting nitric oxide (NO)-synthase on fluid transport, mucosal cyclic GMP and cyclic AMP levels and intraluminal prostaglandin E2 (PGE2)-release were studied in a model of ligated jejunal loops of anaesthetized rats in vivo. Experiments were performed under basal conditions as well as under conditions, when net fluid secretion was induced by Escherichia coli heat stable enterotoxin a (E. coli STa) or PGE2. 2. Intravenous infusion of the NO-synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 0.25-50 mg kg-1, 45 min) dose-dependently reversed net fluid absorption to net secretion, whereas infusion of D-NAME, the inactive enantiomer of L-NAME, in corresponding doses did not influence net fluid transport. N omega-nitro-L-arginine (L-NOARG, 25 mg kg-1), another NO-synthase inhibitor, also elicited net secretion of fluid. 3. L-NAME (25 mg kg-1)-induced net fluid secretion was reversed to net absorption by infusion of L-arginine (400 mg kg-1) or sodium nitroprusside (1 mg kg-1) and s.c. administration of indomethacin (10 mg kg-1). Hexamethonium (1 mg kg-1, s.c.), a ganglionic blocker and granisetron (100 micrograms kg-1, s.c.), a 5-HT3-receptor antagonist, did not influence L-NAME-induced net secretion. 4. Net fluid secretion induced by intraluminal instillation of E. coli STa (10 units ml-1) was enhanced by infusion of L-NAME (25 mg kg-1) and was inhibited by infusion of L-arginine (400 mg kg-1) and sodium nitroprusside (1 mg kg-1). D-Arginine (400 mg kg-1) did not influence E. coli STa-induced fluid secretion. Likewise, net fluid secretion induced by i.a. infusion of PGE2 (79 ng ml-1, 30 min) was enhanced by infusion of L-NAME and was inhibited by L-arginine and sodium nitroprusside. D-Arginine(400 mg kg-1) did not influence PGE2-induced fluid secretion.5. PGE2 levels in intraluminal fluid were not elevated after infusion of L-NAME (25mgkg-1) compared to controls.6. Mucosal cyclic GMP and cyclic AMP levels after L-NAME-treatment were not different from control values.7. These results indicate that nitric oxide plays an important role in the regulation of intestinal fluid transport. The data suggest a nitric oxide-dependent proabsorptive tone in the intestine, which possibly involves the enteric nervous system and suppression of prostaglandin formation. This proabsorptive tone also may downregulate fluid secretion induced by E. coli STa or PGE2.

Jejunal release of prostaglandin E2 in Crohn's disease: relation to disease activity and first-degree relatives

Patients with Crohn's disease of the distal ileum show increased permeability to hyaluronan and increased release of histamine and complement components in uninvolved parts of the proximal jejunum. These abnormalities are related to disease activity, and are not found in first-degree relatives. Increased synthesis of prostaglandins has been observed in inflamed areas of the intestine in active Crohn's disease. Our purpose was to measure luminal prostaglandin release in patients with active and inactive Crohn's disease and their first-degree relatives. Twenty-four patients with Crohn's disease of the distal ileum (10 in remission and 12 with inflammatory activity) and 17 of their first-degree relatives were included and compared with healthy control subjects (n = 39). Ten centimetres of the proximal jejunum was isolated between balloons as described previously and perfused with a balanced electrolyte glucose-containing solution. Luminal concentrations of PGE2 and albumin were measured and their luminal release was calculated. Luminal release of PGE2 was significantly higher in patients with Crohn's disease than in control subjects [69.7 +/- 11.5 and 34.0 +/- 4.7 pg/cm per h (3.7 +/- 0.6 and 1.8 +/- 0.3 ng/L), respectively, P < 0.01]. The PGE2 levels, however, were not positively correlated to disease activity. Furthermore, there was a modest, but significant increase in luminal PGE2 in first-degree relatives [53.6 +/- 7.0 pg/cm per h (2.9 +/- 0.4 ng/L), P < 0.05]. These changes were not accompanied by significant changes in luminal permeation of albumin.(ABSTRACT TRUNCATED AT 250 WORDS)

Inflammation as a major cause of fluid losses in small-bowel obstruction

The importance of inflammation for fluid losses in obstructive ileus was investigated in vivo in the rat. Inflammation was quantified by spectrophotometry of extravasated Evans blue (Eb)-albumin. Net fluid secretion in the obstructed jejunum was measured by a continuous gravimetric technique. The inflammation in the obstructed gut wall was significantly more pronounced than that in the gut distal to the obstruction and the sham-obstructed gut. The inflammation was significantly more pronounced in the serosa and external muscle layer than in the mucosa-submucosa. Acid-base balance in obstructed animals showed a significant metabolic alkalosis, whereas serum albumin and electrolytes were normal. Lumen fluid in obstructed animals showed low levels of albumin and total calcium as compared with serum, whereas fluid from the peritoneal cavity of obstructed rats showed high contents of albumin. Indomethacin and hydrocortisone given intravenously to obstructed animals significantly reduced the degree of extravasated Eb-albumin in the obstructed gut wall. Sham-operated animals showed net fluid absorption, whereas obstructed rats showed net fluid secretion. Secretion in obstructed animals was in all cases reversed into net fluid absorption after intravenous administration of indomethacin and hydrocortisone. These findings suggest that a pronounced inflammation occurs in the wall of the obstructed small intestine and that this inflammation plays an important role in the pathogenesis of the profuse fluid losses of obstructive ileus.

Acute effects of smoking during modified sham feeding in duodenal ulcer patients. An analysis of nicotine, acid secretion, gastrin, catecholamines, epidermal growth factor, prostaglandin E2, and bile acids

Smoking is associated with an increased incidence of duodenal ulcer with a high relapse rate, and smokers tend to be slow healers. The etiology responsible for this remains unknown, and there is general disagreement as to whether smoking affects gastric secretion. The aim of the present study was to investigate both aggressive and protective factors in response to vagal stimulation induced by modified sham feeding (MSF) in duodenal ulcer patients when smoking versus not smoking. On smoking days, nicotine concentrations in plasma averaged about 15 ng/ml and were extremely high in saliva and gastric juice (> 1300 and > 800 ng/ml, respectively). MSF induced a significant decrease in intragastric pH during non-smoking (p = 0.01) but not during smoking. Acid output 1 h after MSF was lower on smoking than on non-smoking days (p = 0.02), as was volume secretion (p = 0.02). Plasma gastrin concentrations were significantly increased during MSF on non-smoking days (p = 0.04) but not on smoking days, the concentrations during the whole day being lower on smoking days (p = 0.002). Plasma catecholamine levels were unaffected by MSF, whether smoking or not. However, plasma concentrations of noradrenaline decreased during the smoking of a single cigarette (p = 0.03), whereas those of adrenaline were increased on smoking days (p = 0.02). Epidermal growth factor concentrations were decreased in gastric juice after MSF during non-smoking (p = 0.01) but not during smoking. Although prostaglandin E2 (PGE2) concentrations in gastric juice were unaffected by MSF, PGE2 output increased after MSF whether smoking or not, the increment being non-significantly less during smoking (p = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibitor of interleukin-1 alpha and interleukin-1 beta-induced T-cell activation in serum of patients with active Crohn's disease

Interleukin-1 is a family of polypeptides with a wide spectrum of immunoinflammatory activities pertinent to Crohn's disease, including T-cell activation. Using specific enzyme-linked immunosorbent assays, only sera from two of 19 patients (11%) with active Crohn's disease contained interleukin-1 alpha and interleukin-1 beta activity. Using the thymocyte proliferation assay, sera from the same patients contained significantly increased inhibitory activity against interleukin-1 alpha (P = 0.025) and interleukin-1 beta-induced cell activation (P = 0.00005) as compared with controls. Changes in both interleukin-1 alpha (P = 0.020) and interleukin-1 beta (P = 0.012) inhibitor concentrations correlated significantly with changes in clinical disease activity. None of the patient sera contained IgG or IgM autoantibodies to IL-1 alpha, nor did they exert significant inhibitory activity against interleukin 1 beta in the fibroblast prostaglandin E2-induction assay. Taken together, these data provide evidence for the presence of one or several regulators of interleukin-1-induced T-cell activation in sera from patients with active Crohn's disease.

Colloidal bismuth subcitrate causes sustained release of gastric mucosal prostaglandin E2

Gastric application of high doses of colloidal bismuth subcitrate (CBS) stimulates mucosal prostaglandin E2 (PGE2) production, which is considered part of the mechanism by which the drug accelerates peptic ulcer healing. Whether therapeutic, orally administered, doses of CBS cause a sustained stimulation of prostaglandin production is not known. We have, therefore, determined gastric luminal release of PGE2 during 'steady-state' perfusion of the stomach with CBS (10 mg/ml; isotonic mannitol 5 ml/min) and 4 h after the last oral dose of the drug (240 mg b.d.) for 2 weeks (isotonic mannitol 5 ml/min) in 8 healthy volunteers. A significant increase in PGE2 concentrations (712 (409-1076) vs. control 334 (252-655) pg/ml; medians with Q50 ranges; P less than 0.02) and PGE2 output (12.5 (7.3-14.3) vs. control 4.8 (4.1-7.3) ng/15 min; P less than 0.02) occurred during gastric perfusion with CBS. A similar increase in PGE2 concentrations (630 (297-1429) pg/ml; P less than 0.02) and PGE2 output (12.6 (6.4-22.2) ng/15 min; P less than 0.02) was observed following treatment with CBS for 2 weeks. These results suggest that therapeutic doses of CBS cause a sustained stimulation of gastric mucosal PGE2 formation.

Modulation of fluid absorption and the secretory response of rat jejunum to cholera toxin by dietary fat

To study the effects of dietary fat on jejunal water and ion absorption and on cholera toxin-induced secretion, 3 week old Sprague Dawley rats were fed isocaloric diets. Forty per cent of the total calories were given as fat, as butter (high saturated fat), olive oil (high monounsaturated fat), or corn oil (high polyunsaturated fat), with one group on low fat (10% of calories) standard laboratory diet as controls. During in vivo jejunal perfusion studies we found that (i) a polyunsaturated fat (corn oil) supplemented diet improves jejunal absorption of water and electrolytes and these changes are independent of the observed concentrations of luminal prostaglandins; (ii) high dietary fat appreciably reduced the secretory response to cholera toxin, probably without fundamentally changing the mechanism by which cholera toxin induces secretion. We conclude that dietary fat composition altered the permeability and transport characteristics of the small intestine. This observation might have relevance to some human diarrhoeal disorders.

Proximal duodenal prostaglandin E2 release and mucosal bicarbonate secretion are altered in patients with duodenal ulcer

Proximal duodenal mucosal bicarbonate production is impaired in patients with duodenal ulcer disease. Because prostaglandins of the E class increase human proximal duodenal bicarbonate secretion, this study tested the hypothesis that endogenous prostaglandin E2 production is defective in patients with duodenal ulcer. Ten patients, five with active and five with inactive duodenal ulcer disease, were studied along with 10 normal volunteers. The proximal 4 cm of duodenum, the bulb, was isolated and continuously perfused with 154 mmol/L NaCl. Basal bicarbonate secretion was measured for 30 minutes. The test segment was then acidified with a physiological amount of HCl (2 mmol over 5 minutes), and acid-stimulated bicarbonate secretion was measured by pH/PCO2 and back-titration for 55 more minutes. Prostaglandin E2 was measured in the effluents by a radioimmunologic assay validated by gas chromatography-mass spectrometry. Compared with the normal subjects after luminal acidification, the duodenal ulcer patients had significantly greater PGE2 release and decreased total 1-hour bicarbonate output. The peak 5-minute acid-stimulated bicarbonate responses were not significantly different between the duodenal ulcer patients and normal subjects. After luminal acidification, PGE2 output remained elevated in the duodenal ulcer patients but returned promptly to basal in the normal subjects. Furthermore, the ratio of bicarbonate secreted to the amount of PGE2 released was significantly less in the ulcer patients. These findings suggest that patients with duodenal ulcer disease have an impaired mucosal bicarbonate response to endogenous PGE2. The increased acid-stimulated PGE2 response in duodenal ulcer patients suggests a compensatory phenomenon in response to the diminished mucosal bicarbonate production.

Inflammation as a diagnostic keystone and its clinical implications, exemplified by the inflammatory bowel diseases

Inflammation is a complex process following sublethal injury to tissue and ends with permanent destruction of tissue or with healing. Inflammation has long, long roots in the evolutionary process and as a concept reaches far back in the history of medicine. Inflammation can not be viewed solely in a teleological perspective. Refined by phylogenesis it serves the integrity and survival of groups (species etc.) and not primarily individuals. Inflammation has, in the history of science, been studied on the macroscopic, the microscopic, the dynamic cellular, the immunological, the biochemical/physiological, and the molecular level. Clinicians have for centuries relied on inflammatory signs and symptoms in their diagnostics, even to the extent of being seriously confused, when a subject's inflammatory preparedness is disturbed, as in agranulocytosis, alcoholism, HIV-infection etc. Chronic inflammatory bowel diseases (ulcerative colitis and Crohn's disease) have been studied intensively by inflammologists. The results are partly exchangeable with studies in, for instance, chronic rheumatoid arthritis. They try to answer the over-all question in these diseases: Are we dealing with a normal inflammatory preparedness confronted with a special (unknown) agent, or an abnormal inflammatory preparedness confronted with an ubiquitous agent? The answer will form the basis for the future treatment of these patients, whose diseases remind us of inflammation as man's fellow traveller on "the long phylogenetic march".

Involvement of 5-hydroxytryptamine, prostaglandin E2, and cyclic adenosine monophosphate in cholera toxin-induced fluid secretion in the small intestine of the rat in vivo

The diarrhea of cholera is considered to rely solely on a cyclic adenosine monophosphate-mediated secretory mechanism. However, both 5-hydroxytryptamine and prostaglandin E2 have been proposed to be involved in the pathogenesis of cholera. In vivo experiments were performed, therefore, in the rat jejunum to investigate the influence of purified cholera toxin on fluid secretion, luminal release of 5-hydroxytryptamine and prostaglandin E2, and formation of mucosal cyclic adenosine monophosphate. Also the effects of ketanserin, indomethacin, verapamil, and nifedipine on the named parameters were studied. Cholera toxin dose-dependently (0.1-0.5 microgram/ml) and time-dependently (1-5 h) increased mean net fluid secretion with a maximum response at 4 h. It also caused a significant (p less than 0.01) rise in release of 5-hydroxytryptamine and prostaglandin E2, in addition to formation of cyclic adenosine monophosphate. The dose-response curve for cholera toxin-induced fluid secretion was shifted to the right by indomethacin (10 mg/kg s.c.) and ketanserin (200 micrograms/kg s.c.), none of which caused a change in cholera toxin-induced release of 5-hydroxytryptamine. However, both agents significantly decreased the release of prostaglandin E2. Verapamil (0.2-9.5 micrograms/min i.a.) and nifedipine (0.05-0.5 microgram/min i.a.) dose-dependently reduced cholera toxin-induced fluid secretion. The estimated local concentrations at half-maximal inhibition were 5 x 10(-7) M verapamil and 5 x 10(-8) M nifedipine, respectively. The cholera toxin-induced increase in release of 5-hydroxytryptamine and prostaglandin E2 and formation of cyclic adenosine monophosphate was unaffected by verapamil. These results support the concept that cholera toxin-induced fluid secretion in vivo is caused, in part, by release of 5-hydroxytryptamine, which in turn stimulates formation of prostaglandin E2.

Prostaglandin E2 is a mediator of 5-hydroxytryptamine induced water and electrolyte secretion in the human jejunum

Studies in the rat jejunum in vivo have shown that 5-hydroxytryptamine (5-HT) causes secretion of fluid and luminal release of prostaglandin (PG) E2. These effects can be blocked by indomethacin and ketanserin, which suggests that PGE2 may be an important intermediate in the transduction mechanism leading to 5-HT induced fluid secretion. To test this hypothesis in man 'steady state' perfusions (9 ml/min) were done in eight healthy volunteers using the triple lumen technique. The proximal jejunum was perfused with Ringer's solution which contained 51Cr-EDTA as a non-absorbable marker. Before and after the administration of indomethacin (1.0 mg/kg iv) the effects of exogenous 5-HT (10 micrograms/kg/min iv) on jejunal net transport of fluid and electrolytes and jejunal flow rate (JFR) of PGE2 were measured in 15-min periods for 2 x 60 minutes after a 60 minute control period. 5-HT reversed fluid and electrolyte absorption into profuse secretion (p less than 0.01, Duncan's multiple range test) and significantly increased JFR of PGE2 (p less than 0.01). Indomethacin partly restored fluid and electrolyte absorption (p less than 0.01) and inhibited JFR of PGE2 (p less than 0.05). These results provide further evidence in favour of the theory that PGs are involved in 5-HT induced intestinal fluid secretion.

Use of colonic eicosanoid concentrations as predictors of relapse in ulcerative colitis: double blind placebo controlled study on sulphasalazine maintenance treatment

To establish whether concentrations of eicosanoids determined by equilibrium in vivo dialysis of faeces and equilibrium in vivo dialysis of rectum might predict a relapse in ulcerative colitis, 23 patients with completely inactive disease, maintained on sulphasalazine, stopped treatment and entered a prospective study. Concentrations of prostaglandin E2 were determined by radioimmunoassay on purified faecal and rectal dialysates at entry, at two weeks, and at two, six, and 12 months. If the above concentrations exceeded control concentrations (0.5 ng/ml and 1.0 ng/ml in faecal and rectal fluid, respectively) at any study day, the patient was allocated at random to double blind treatment with sulphasalazine 2 g/day, or placebo for six months. A relapse, defined as recurrence of symptoms accompanied by endoscopic inflammation occurred in none of six and in four of five patients allocated to sulphasalazine and placebo, respectively (p less than 0.05). In no case a normal rectal prostaglandin E2 concentration was associated with a relapse in the short term, but only two of 12 patients observed passively remained in remission. In retrospect, leukotriene B4 was a less sensitive predictor of relapse than prostaglandin E2. We conclude that raised concentrations of prostaglandin E2 in rectal dialysis fluid identify patients with a substantial risk of relapse.

In vivo profiles of eicosanoids in ulcerative colitis, Crohn's colitis, and Clostridium difficile colitis

To compare the local release of arachidonic acid metabolites in inflammatory diarrheal disease, in vivo equilibrium dialysis of the rectum was done in consecutive untreated patients with ulcerative colitis (n = 20), Crohn's colitis (n = 10), and Clostridium difficile colitis (n = 7). All patients had endoscopically proven rectal inflammation. Eicosanoid profiles were determined in rectal dialysates by radioimmunoassay after preliminary purification. Concentrations of prostaglandin E2, prostaglandin F2 alpha, and thromboxane B2, but not 6-keto-prostaglandin F1 alpha, were raised in all groups and compared with healthy controls. The highest levels within each group were obtained in patients with widespread epithelial damage, as judged by endoscopy. In patients with ulcerative colitis, an extreme rise in prostaglandin E2 and thromboxane B2 were observed. Similarly, concentrations of leukotriene B4 were substantially increased in ulcerative colitis, but in Crohn's colitis and Clostridium difficile colitis only those patients with rectal ulcerations showed elevations. These findings probably reflect more severe tissue damages in ulcerative colitis, but differences between disease groups in cell-to-cell interaction may also contribute. The data suggest, therefore, that therapeutic inhibition of lipoxygenase pathways may prove more effective in ulcerative colitis than in Crohn's disease.

Longterm olsalazine treatment: pharmacokinetics, tolerance and effects on local eicosanoid formation in ulcerative colitis and Crohn's colitis

To examine pharmacokinetics and tolerance of long term administration of olsalazine (azodisalicylate), increasing doses of the drug were given for one year to 31 patients with ulcerative colitis (UC) and nine patients with Crohn's colitis (CC), refractory to, or intolerant of sulphasalazine, until sustained remission was obtained or a maximum of 4 g/day was reached. Colonic drug metabolism was studied by equilibrium in vivo dialysis of faeces. Complete azoreduction occurred in most cases. Concentrations of 5-aminosalicylic acid, but not N-acetyl-5-aminosalicylic acid, in faecal dialysates increased dose dependently. Serum concentrations disclosed no cumulation in the long term and olsalazine was well tolerated, although loose stools occurred transiently in some patients with extensive disease: this was associated with a larger proportion of unsplit olsalazine in the faecal dialysates. Patients with ulcerative colitis having a high prostaglandin E2 concentration (greater than ng/ml) determined by equilibrium dialysis of rectum, were less likely to benefit from treatment. Olsalazine is a very effective means of delivery of 5-aminosalicylic acid to the colonic mucosa in active disease. Use of the drug in controlled trials may be considered safe even in prolonged high dosage.

Colonic prostaglandin E2 levels and olsalazine metabolism in relapsing ulcerative colitis: implications for controlled trials in the long term

To examine the tolerance and pharmacokinetics of long-term olsalazine administration, increasing doses of the drug were given to 31 patients with ulcerative colitis. All patients were refractory to or intolerant of sulphasalazine. Complete azo-reduction occurred in most cases. Concentrations of 5-ASA, but not acetyl-5-ASA, in faecal dialysates increased dose-dependently. Estimates of efficacy were more favourable among those intolerant of sulphasalazine. Patients with high prostaglandin E2 levels determined by equilibrium in vivo dialysis of rectum were less likely to benefit from treatment. In conclusion, olsalazine is a highly effective means of delivering 5-ASA to the colonic mucosa. Long-term use of olsalazine in controlled trials may be considered safe, even in high doses.

Does vitamin E supplementation modulate in vivo arachidonate metabolism in human inflammation?

To determine whether supplementation with the physiological radical scavenger, vitamin E, would modulate arachidonate metabolism in human inflammation, we performed equilibrium dialysis of rectum in eight patients with active ulcerative colitis confined to the rectum. The patients, all off drug treatment, were supplemented with 1920 IU/day of alpha-tocopherol and had rectal dialysis done at entry and after three and 14 days. Luminal concentrations of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4), determined by radioimmunoassay in purified dialysates, were significantly raised compared to healthy controls. Supplements caused no change in these levels either at day 4 or 15, although serum-tocopherol showed a 3-fold increase. Also disease activity was unaffected. This failure of vitamin E supplementation to suppress the mucosal release of PGE2 and LTB4 in active inflammation does not encourage controlled trials on the effect of oral vitamin E in ulcerative colitis.

In vivo effects of orally administered prednisolone on prostaglandin and leucotriene production in ulcerative colitis

It has been proposed that anti-inflammatory actions of corticosteroids rely on promotion of a natural peptide phospholipase A2 inhibitor, lipocortin, but in vivo effects on arachidonic acid metabolism have not been shown. Equilibrium dialysis of the rectum in patients with ulcerative colitis was used to determine whether cyclooxygenase and lipoxygenase products released from the inflamed rectal mucosa could be differentially inhibited by systemic treatment with prednisolone and indomethacin, respectively. In 10 patients with severe disease luminal concentrations of prostaglandin E2, prostaglandin F2 alpha, and leucotriene B4 were markedly raised (p less than 0.05) on comparison with 10 healthy controls, and they decreased significantly (p less than 0.05) within 72 hours after administration of prednisolone 1.5 mg/kg/day orally. In contrast prostaglandin, but not leucotriene B4 concentrations decreased (p less than 0.05) within 72 hours after administration of indomethacin 150 mg/day in another 10 patients with distal disease. These prompt reductions in concentrations of arachidonic acid metabolites more likely are caused by direct drug actions, rather than being secondary to decreased tissue damage. The data accord with the theory explaining anti-inflammatory effects of corticosteroids through lipocortin activity and support the belief that leucotrienes are more important than prostaglandins as mediators of inflammation in ulcerative colitis.

The role of eicosanoids in the gastrointestinal tract

Exploring the role of eicosanoids in the gastrointestinal tract entails fundamental problems of methodology and interpretation. Most important are the difficulties inherent in the choice of an experimental design which prevents non-specific stimulation of eicosanoid formation, because any perturbation of cell membranes will initiate eicosanoid synthesis. In addition to cyclic nucleotides, prostaglandins may serve as intracellular mediators for the stimulus of secretion coupling via intracellular free calcium in the gastrointestinal epithelial cells. By contrast, the effects of supraphysiological doses of prostaglandins parallel those of cyclic AMP-dependent secretagogues such as VIP, which increases calcium through activation of the mucosal adenylatecyclase. The question of whether patients develop gastric or duodenal ulcers as a result of a prostaglandin deficiency remains open. The synthetic prostaglandin analogues available commercially for anti-ulcer therapy appear to be unable to accelerate the healing of peptic ulcers unless they are administered in anti-secretory doses, and are unlikely to have a substantial effect on patients with bleeding from ulcerative lesions in the gastro-duodenal mucosa. Prostaglandins of the E type mediate, at least partly, the diarrhoea associated with a large number of clinical conditions and various pharmacological agents. Several types of secretory diarrhoea respond to drugs that inhibit prostaglandin biosynthesis. Whether eicosanoids are mediators, or merely epiphenomena, of inflammation in ulcerative colitis and Crohn's disease remains unclear. Improved knowledge of their functional role of eicosanoids has nevertheless allowed a reinterpretation of the rationale behind current therapy. Uncontrolled formation of eicosanoids may not only be the source of diarrhoea in colonic inflammation, but may also be critical for cell proliferation and the development of dysplasia in long-standing disease.

Effect of azodisal sodium and sulphasalazine on ileostomy output of fluid and PGE2 and PGF2 alpha in subjects with a permanent ileostomy

Azodisal sodium is a highly effective means of oral delivery of 5-amino-salicylic acid to the colonic mucosa. Administration of this drug to patients intolerant of sulphasalazine, however, occasionally results in liquid stools. In preliminary experiments, which comprised 10 healthy volunteers treated with colectomy for ulcerative colitis, ileostomy fluid output increased (p less than 0.001) during oral intake of azodisal sodium (1 g/day). In a double blind, placebo controlled crossover study, comprising eight similar volunteers, ileostomy fluid output increased (p less than 0.05) in a dose related manner during intake of azodisal sodium (1 g/day vs 2 g/day) compared with placebo or sulphasalazine (2 g/day). Concentrations of prostaglandin (PG)F2 alpha in free ileal water determined by equilibrium in vivo dialysis of ileostomy contents decreased (p less than 0.05) during intake of azodisal sodium (2 g/day), whereas concentrations of PGE2 and the output of PGE2, PGF2 alpha, and 'PGE2 + PGF2 alpha' remained unchanged. Thus increased formation of PGs is apparently not the cause of increased ileostomy fluid output associated with azodisalicylate intake.

Effects of topical 5-aminosalicylic acid and prednisolone on prostaglandin E2 and leukotriene B4 levels determined by equilibrium in vivo dialysis of rectum in relapsing ulcerative colitis

To determine the influence of inflammation and topical treatment with 5-aminosalicylic acid or prednisolone on arachidonic acid metabolism in vivo, we carried out a double-blind controlled study on the release of prostaglandin E2 and leukotriene B4 to the rectal lumen in 24 consecutive patients with proven distally located ulcerative colitis. Before and at days 15 and 29 a dialysis bag was placed in the emptied rectum for 4 h prior to assessing clinical, endoscopic, and histologic disease activity. A single enema was given daily at bedtime (1 g 5-aminosalicylic acid or 25 mg prednisolone) until complete remission or for a maximum of 4 wk. Clinical and endoscopic remission was obtained in 16 (7 on 5-aminosalicylic acid) and 11 (3 on 5-aminosalicylic acid) patients, respectively. Luminal concentrations of prostaglandin E2 and leukotriene B4 were positively correlated to disease activity and significantly decreased among the prednisolone-treated patients. In both treatment groups a decrease toward normal levels occurred in patients responding to therapy. In retrospect, the pretreatment prostaglandin E2 and leukotriene B4 levels were significantly higher in patients not responding to therapy than in those improving during treatment. In conclusion, luminal prostaglandin E2 and leukotriene B4 levels may prove more useful predictors of the outcome of treatment in relapsing ulcerative colitis than clinical indices of disease activity.

Significance of calcium for the prostaglandin E2-mediated secretory response to 5-hydroxytryptamine in the small intestine of the rat in vivo

5-Hydroxytryptamine (5-HT) has been claimed to mediate intestinal secretion in morphine withdrawal diarrhea through stimulation of local prostaglandin formation without involving cyclic adenosine monophosphate. Therefore, experiments were performed to study (a) the effects of exogenous 5-HT and the cyclic adenosine monophosphate-dependent secretagogue, vasoactive intestinal polypeptide, on intestinal prostaglandin E2 (PGE2) formation and (b) the involvement of calcium in the secretory response to close intraarterial infusion of 5-HT, PGE2, or vasoactive intestinal polypeptide in tied-off loops of rat jejunum in vivo. 5-Hydroxytryptamine and vasoactive intestinal polypeptide reversed fluid absorption to net secretion (p less than 0.01), but only 5-HT caused an increase in luminal PGE2 output (p less than 0.01). Indomethacin and d,l-verapamil prevented only the secretory effect of 5-HT. Exogenous PGE2 (1.6-160 ng/min) reversed absorption to secretion (p less than 0.01) in a dose-dependent manner, irrespective of whether the rats were pretreated with indomethacin or not. Racemic and l-verapamil, but not d-verapamil, markedly reduced (p less than 0.01) the secretory effect of physiologically low doses of PGE2 (1.6 and 16 ng/min), whereas high doses of PGE2 (160 ng/min), which caused a significant increase in mucosal cyclic adenosine monophosphate (p less than 0.005), were not inhibited by verapamil. These data suggest that PGE2 may be an important intermediate in the transduction mechanism leading to 5-HT-induced intestinal secretion, and that physiologic doses of PGE2 may act by facilitating calcium entry, rather than by increasing intracellular calcium through activation of the adenylate cyclase.

Prostaglandin E2 formation by the gall bladder in experimental cholecystitis

Both experimental cholecystitis and luminal distension inhibit fluid absorption and stimulate motor activity in the gall bladder. These functional alterations are mimicked by exogenous prostaglandins (PGs) and inhibited by potent cyclooxygenase inhibitors, but direct evidence of a primary role of endogenous PGs is not available. Therefore, experiments in the cat were carried out in which the effects of lyso-phosphatidylcholine (lysoPC; 0.5-2.0 mmol/l), implantation of cholesterol stones, and raised intraluminal pressure in the gall bladder lumen were assessed. The gall bladder was perfused in vivo at a constant rate by a buffer solution. PGE2 was determined in the effluent by a radioimmunological method validated by gas chromatography-mass spectrometry. PGE2 output was markedly (p less than 0.01) raised (13.9 +/- 2.6 vs 1.1 +/- 0.5 ng/h; n = 10) during lysoPC perfusions and this response was inhibited by 66% (p less than 0.02) after indomethacin administration (2 mg/kg iv). A significant (p less than 0.05) increase in PGE2 output occurred six weeks after implantation of gall stones (3.7 +/- 1.5 ng/h; n = 6) and in response to distension of the normal gall bladder wall (3.6 +/- 1.2 ng/h; n = 6). These findings support the theory that PGs play an important pathophysiologic role in biliary tract disease.

Prostaglandins and the gastrointestinal mucosa: are they important in its function, disease, or treatment?

In 1971 interest in the role of prostaglandins in the gastrointestinal tract was stimulated by the publication of two hypotheses--that aspirin damaged the gastric mucosa by inhibiting prostaglandin synthesis (1) and that cholera toxin caused diarrhea by stimulating it (2). Subsequent research into the gastrointestinal actions of prostaglandins has been considerable and now impinges on clinical practice. This paper reviews the involvement of prostaglandins and related compounds in mucosal protection, in ulcer healing, in diarrhea, and in gastrointestinal inflammation, with particular reference to the growing body of human data.

Stimulation of PGE2 synthesis and water and electrolyte secretion by senna anthraquinones is inhibited by indomethacin

The effect of dried senna pod extract, containing 10% sennoside B, on colonic electrolyte and fluid transport was examined in the anaesthetized rat in-situ. Oral administration of senna pod extract dose-dependently (17.5-30 mg kg-1, calculated as sennoside B) reversed net absorption of water, sodium and chloride to net secretion and increased potassium secretion. Senna pod extract stimulated the output of prostaglandin E2 into the colonic lumen. Inhibition of prostaglandin biosynthesis by pretreatment of the rats with indomethacin (10 mg kg-1) significantly inhibited the effects of senna pod extract (17.5-30 mg kg-1) both on net fluid transport and on prostaglandin E2 synthesis. The inhibitory effect of indomethacin on net fluid transport induced by senna pod extract (30 mg kg-1) was dose-dependent. It is concluded that anthraquinones exert their laxative action at least partially via stimulation of colonic fluid and electrolyte secretion, and that this secretion is mediated by stimulation of endogenous prostaglandin E2 formation.

Increased jejunal prostaglandin E2 concentrations in patients with acute cholera

Supraphysiologic doses of prostaglandins (PGs) mimic the effect of cholera toxin and cAMP in the small intestine, but not all observations are explicable in terms of the theory that links PGs to cAMP. Because no data exist on endogenous PGs in human cholera we measured PGE2 concentrations in jejunal fluids and fasting intestinal flow rates of PGE2 during slow marker perfusion of proximal jejunum in nine patients with high purging cholera. Nine patients in the recovery phase of cholera or other watery diarrhoeas served as controls. In acute cholera PGE2 concentrations were significantly (p less than 0.001) raised (172-1435 (n = 9) vs 60-270 (n = 9) pg/ml) and negatively correlated (r = 0.71; p less than 0.05) to the time following onset of diarrhoea. Also fasting jejunal flow rates of PGE2 were significantly (p less than 0.005) increased (0.77-8.22 (n = 7) vs 0.21-0.92 (n = 6) ng/min), and positively correlated (r = 0.84; p less than 0.01) to stool output (2.9-9.5 ml/min). By extrapolation, at normal stool output fasting jejunal flow rates of PGE2 equalled those measured during convalescence. The results support the notion that PGs, in addition to cAMP, may play a pathophysiologic role in human cholera. As the ratio between the medians of the highest values measured during the acute phase of cholera and in late convalescence was at least 15, local intestinal PGE2 formation in full blown cholera should result in mucosal PGE2 concentrations above those required for a maximal secretory response. This observation might explain why conventional doses of aspirin and indomethacin had no significant antidiarrhoeal effect in clinical trials.

Irritable bowel syndrome: current concepts and future trends

About five per cent of the adult population each year will see their doctor with complaints that are finally characterised as irritable bowel syndrome (IBS). The complaints are constipation (perhaps alternating with diarrhoea), abdominal pain (dull or colicky), abdominal distension, abdominal rumbling and flatulence. The diagnosis of IBS implies that a relevant examination has precluded any organic disease. The etiology is unknown and the syndrome probably does not represent a disease entity. It is therefore difficult, if not impossible, to produce a definite rationale of treatment. However, several aspects of the pathogenesis of the individual symptoms of IBS are well known: 1) chronic constipation is most likely due to fibre-depleted diet, psychological factors, local organic disorders (e.g., anal fissures, hemorrhoids, diverticulosis) and disturbance of the body fluid balance (e.g., high consumption of diuretic compounds such as coffee and tea); 2) pain is related to spasms and motility disturbances causing increased intraluminal pressure; 3) meteorism is not due to an increased amount of intestinal gas, but "air traps" and segmental accumulation of gas seem to occur. Furthermore, psychopathological factors and perhaps also food intolerance may play an etiological role. At present the rationale of treatment in IBS is: 1) management of constipation, 2) ease of spasms, 3) reduction of surface tension of intestinal contents, 4) ease of mental stress.

Effects of sulphasalazine and disodium azodisalicylate on colonic PGE2 concentrations determined by equilibrium in vivo dialysis of faeces in patients with ulcerative colitis and healthy controls

The role of arachidonic acid metabolites and the mode of action of 5-aminosalicylic acid, the active moiety of sulphasalazine and disodium azodisalicylate, in ulcerative colitis remain obscure. Therefore, experiments were performed in which the effects of medication on immunoreactive prostaglandin (PG) E2 concentrations in free faecal water were assessed using the equilibrium in vivo dialysis of faeces. Colonic PGE2 concentrations in patients with active ulcerative colitis (n = 11) ranged from 2035-18,000 pg/ml to be compared with a range of 103-188 pg/ml in healthy volunteers (n = 10; p less than 0.001). In all healthy volunteers PGE2 concentrations decreased slightly (p less than 0.05) after disodium azodisalicylate intake 2 g/day, whereas low dose disodium azodisalicylate (0.25 g/day) caused no change. In patients with ulcerative colitis in complete clinical, sigmoidoscopic, and histologic remission withdrawal of sulphasalazine (2 g/day; n = 6) increased PGE2 concentrations to values above normal levels (p less than 0.05) which returned to pretrial values (p less than 0.05) on disodium azodisalicylate (2 g/day; n = 7). In conclusion, increased PGE2 in free faecal water indicates an abnormality in the colonic mucosa, even in the absence of conventional signs of inflammation. We could not confirm the hypothesis that sulphasalazine and 5-aminosalicylic acid exert their therapeutic effect through promotion of endogenous cytoprotective prostaglandins. In contrast, the observation that raised PGE2 concentrations were normalised by disodium azodisalicylate in patients with inactive ulcerative colitis suggests that subclinical disease activity was decreased by 5-aminosalicylic acid.

Evaluation of the role of prostaglandins E and F in human cholecystitis

The role of chemical mediation by arachidonic acid metabolites of inflammation in human cholecystitis was evaluated by comparing gallbladder PGE and PGF formation to the degree of inflammation present. Twenty-five human gallbladders containing stones were operatively removed. A strip of fundus was used for histologic evaluation. In a blinded fashion, three pathologists quantitated the amount of inflammation present using a histologic scoring system. Gallbladder mucosal cells were separated from muscle wall by submucosal injection of EDTA and shaking in tissue culture media. Separated mucosal cells and finely minced muscle wall were maintained in tissue culture medium for 3 hours. Hourly PGE and PGF levels in media (extracellular) and mucosal cell and muscle tissue homogenate (intracellular) PGE and PGF concentrations were determined by radioimmunoassay. PGE production increased by both mucosal cell and muscle tissue with increasing inflammation. A significant positive linear correlation existed between the histologic score of inflammation and PGE production by gallbladder mucosal cells and muscle tissue. No correlation existed between the amount of inflammation present and PGF production by mucosal cells or muscle tissue. The results demonstrate an increase in PGE production by human gallbladder tissue with increasing inflammation and suggest that arachidonic acid metabolites may be important mediators of the inflammatory process in human cholecystitis.

Colostomy irrigation with prostaglandin E2 and bisacodyl. A double-blind cross-over study

The emptying of the colon and the side-effects after intraluminal application of prostaglandin E2 and of bisacodyl in 14 patients was studied by employing colostomy irrigation. The design was double-blind with cross-over, the irrigation was one litre of tap water to which was added in randomized sequence placebo, prostaglandin *2 (350, 700 and 1400 micrograms) or bisacodyl (1.25, 2.5 and 5 mg). Neither prostaglandin E2 nor bisacodyl had any significant effect.

Effects of extrinsic denervation on net water transport and motility of the feline gallbladder in vivo

The influence on the concentrating ability of the gallbladder after extrinsic denervation was studied in anesthetized cats, previously subjected to truncal vagotomy, and/or celiacectomy , and compared with sham-operated controls. Net water absorption was studied by perfusion techniques. Acute experiments were performed under basal conditions and alpha-adrenoceptor stimulation (iv infusion of norepinephrine (NE), 1 micrograms/kg X min). Gallbladder biopsies were studied by fluorescence microscopy to visualize and quantitate catecholamines. Three weeks after celiacectomy basal absorption had decreased significantly. In the short-term vagotomy group no changes were demonstrated. However, in the long-term vagotomy group there was a fourfold increase in absorptive capacity, which decreased to control levels after alpha-adrenoceptor blockade (phentolamine 1 mg/kg iv). Long-term vagotomy with subsequent celiacectomy caused no significant changes. Infusion of NE increased net water absorption by 70 +/- 16% in all experimental groups except in long-term vagotomized animals, where the high basal absorption was not further augmented. One hour after NE infusion controls returned to basal absorption rate, while denervated cats remained at stimulated levels. In long-term vagotomized gallbladders there were morphological signs of adrenergic proliferation (increased total number of nerve terminals, sprouting, and elevated levels of intraneuronal NE). In conclusion these results suggest that the adrenergic nervous system is important for full absorptive capacity of the gallbladder. The increased absorption after long-term vagotomy, abolished after alpha-adrenoceptor blockade, might well be explained by the parallel adrenergic proliferation. This hypothesis was further corroborated in animals with long-term vagotomy, where subsequent surgical adrenergic denervation restored basal absorption to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Colonic transport of water and electrolytes in a patient with secretory diarrhea due to collagenous colitis

Whole colon perfusion studies and measurements of luminal prostaglandin E2 were carried out in a 41-year-old female with collagenous colitis to investigate pathophysiological mechanisms for the diarrhea. Biopsies of the colorectal mucosa had revealed a continuous 25- to 60-micron subepithelial collagenous layer, but normal junctional complexes and capillaries. When the patient fasted, the diarrhea persisted and fecal electrolytes, as estimated from the concentration of sodium, potassium, and their anions, accounted for all the osmolality (284 mosm/kg) of stool water, the pH of which was above 8.0. The lumen-negative electrical potential difference in the rectum was -64 mV vs -45 +/- 2 mV (mean +/- SEM) in healthy controls. Profuse secretion of fluid and electrolytes occurred during colonic perfusion with saline. Transport of sodium appeared to be passive with flux ratios equal to those predicted for passive sodium movements, while chloride transport against a steep electrical gradient indicated active secretion. Perfusion with an "ileal output"-like solution decreased fluid and electrolyte secretion, suggesting that bicarbonate, in addition to chloride, may be a major determinant of secretion rates. Since immunoreactive prostaglandin E2 levels following in vivo equilibrium dialysis of feces ranged from 555 to 650 pg/ml vs 55 to 235 pg/ml (99% confidence limits) in healthy controls, it is speculated that prostaglandins synthesized locally in response to mucosal hypoxia might be the mediators of anion secretion.

Management of cardiac arrest in the community: a survey of resuscitation services

A survey of the English health regions identified nine ambulance based resuscitation schemes. Their structure and function are heterogeneous and their impact on patient survival is often speculative. There is considerable medical, paramedical, and lay enthusiasm for resuscitation schemes but this cannot be harnessed until medicolegal uncertainties are removed and guidelines for development are set out. Better documentation of the benefits of existing schemes should be undertaken so that advanced training of ambulance personnel can proceed rationally.

Effect of carbenoxolone on gastric prostaglandin E2 levels in patients with peptic ulcer disease following vagal and pentagastrin stimulation

The influence of oral carbenoxolone sodium (50 mg X 3 daily) on prostaglandin E2 release into gastric juice has been examined in nine peptic ulcer patients (duodenal ulcer, n = 6; prepyloric ulcer, n = 1; gastric ulcer, n = 2) during modified sham feeding and following bolus stimulation of acid secretion by pentagastrin (6 micrograms/kg). Carbenoxolone increased the overall mean of prostaglandin E2 concentrations in gastric juice following modified sham feeding by 32 +/- 9% (mean +/- SEM; P less than 0.02) and decreased the acidity slightly but significantly (P less than 0.05). A marked rise in prostaglandin E2 levels (46 +/- 11%; n = 5; P less than 0.02) was observed in for duodenal ulcer patients and the patient with a prepyloric ulcer responding to therapy (i.e., pain relief and ulcer healing within 4 weeks of treatment). A significant peak (P less than 0.05) related to modified sham feeding was observed only during medication, while a late gradual increase in prostaglandin E2 levels--not associated with vagal stimulation--occurred both in control and carbenoxolone experiments. No significant differences were observed following pentagastrin stimulation. The initial peak in prostaglandin E2 levels observed during medication favours the notion that the mechanism of drug action relies on inhibition of enzymatic degradation while the late increase in prostaglandin E2 levels may be explained by artificial prostaglandin formation during the aspiration procedure.

Comparison of radioimmunological determinations with gas chromatography mass spectrometry dosage. A study of PGE2 and PGF2alpha in gastrointestinal fluids

The reliability of radioimmunoassays for determination of PGE2 and PGF2alpha in gastrointestinal fluids was checked by two gas chromatographic mass spectrometric methods. Analyses were performed on samples of gastric juice from dogs and man (healthy volunteers), jejunal fluids from patients with celiac disease, mucous discharge from a villous adenoma of rectum, and bathing solutions from the Ussing chamber containing human jejunal mucosa. The radioimmunoassays included extraction and Sephadex LH-20 chromatography as a preliminary purification before quantification was carried out. Gas chromatographic mass spectrometric analysis of PGE2 was performed by monitoring the molecular ion of the trimethylsilyl ether of PGB2 methyl ester, m/z 420 and m/z 424 for the protium and the deuterium form, respectively, while PGF2alpha was quantified as the triacetyl derivative of the methyl ester, using the ion pair (M-3x60) i.e. m/z 314 and m/z 318. Recovery of immunoreactive PGE2 relative to gas chromatographic mass spectrometric dosage was 85.5% + / - 6.5 (mean + / - SEM; n=13), while the amount of PGF2alpha in the same sample volume was at the borderline of sensitivity for the gas chromatographic mass spectrometric method used, with a recovery of 114% + / - 19 (mean + / - SEM; n=4).

Colonic cyclic AMP metabolism following chronic ethanol consumption in the rat: effect of hormonal secretagogues

The colonic cyclic AMP system is known to be involved in intestinal secretion and can be stimulated by a variety of gastrointestinal hormones including prostaglandins. We have investigated the effect of chronic ethanol ingestion on the activity of the key enzymes in cyclic AMP metabolism--adenylate cyclase and cyclic AMP phosphodiesterase--in the colonic mucosa of the rat. Chronic ethanol consumption by feeding a nutritionally adequate liquid diet enhanced basal colonic adenylate cyclase activity significantly by 168% (p less than 0.01), but had no effect on colonic low Km cyclic AMP phosphodiesterase activity. In addition, various hormonal secretagogues were used to stimulate colonic adenylate cyclase. Colonic adenylate cyclase exhibited a significantly greater sensitivity and efficacy to prostaglandins and vasoactive intestinal peptide after chronic ethanol ingestion. Since increased intestinal cyclic AMP production due to an increased activity of intestinal adenylate cyclase is known to promote intestinal secretion of water and electrolytes, the frequently observed diarrhea in alcoholics may be explained at least in part by an enhanced production of colonic cyclic AMP.

Release of prostaglandin E2 into gastric juice during stimulation of muscarinic- and gastrin receptors in dogs and in humans

To investigate the causal relationship, if any, between gastric PG formation and gastric acid output, the release of PGE2 into gastric juice has been studied in eight beagle dogs with a gastric fistula, using sustained half-maximal stimulation by bethanechol and pentagastrin, and in eight duodenal ulcer patients, using the combined sham feeding/pentagastrin test. Immunoreactive PGE2 was determined by a method validated by gas chromatography-mass spectrometry and PGE2 values were normalized by expressing them as ng PGE2 released per meq H+ secreted. In the dogs "steady state" PGE2 output (0.4-10 ng/meq H+) was interrupted during continuous i.v. pentagastrin infusion by symmetrical peaks (50-60 minutes of duration) with a maximum of 24 +/- 3.1 ng/meq H+ (mean +/- SEM). During bethanechol stimulation the rhythmic variations were smaller, but the median values for the periods 30 to 180 or 240 minutes significantly (p less than 0.01) higher (3.9-46 ng/meq H+) than in pentagastrin experiments (0.8-20 ng/meq H+). In humans the peak PGE2 output during sham feeding (3.4-41 ng/meq H+) was significantly (p less than 0.02) larger than following bolus stimulation (6/micrograms/kg) by pentagastrin (2.2-18 ng/Meq H+). The findings are consistent with the hypothesis that activation of muscarinic receptors represents the physiologic mechanism by which gastric release of PGs is regulated. Cyclic variations in gastric PG formation appear to occur in response to vagal stimulation since the peaks in PGE2 output were preceded by increased myoelectrical activity (i.e. mean contractile index).