Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum

BACKGROUND

Increased numbers of mast cells and mast cell activation in distal gut segments are associated with symptom onset and severity in irritable bowel syndrome (IBS). Although upper gut symptoms are common, mast cells have not been thoroughly evaluated in proximal gut in IBS patients.

METHODS

Jejunal biopsies obtained by Watson's capsule, aspiration of intestinal fluid and one blood sample were obtained in 20 diarrhoea-predominant patients with IBS (D-IBS) and 14 healthy volunteers (H). Psychological stress (Holmes-Rahe Scale) and depression (Beck's Depression Inventory) were evaluated at baseline and food and respiratory allergy excluded. Biopsies were processed for H&E staining and microscopic inflammation assessed by counting intraepithelial lymphocytes. Mast cells in lamina propria were counted by immunohistochemistry with CD117 (c-kit). Tryptase concentration was measured in intestinal fluid and serum.

RESULTS

D-IBS patients showed higher psychological stress than healthy volunteers (D-IBS: 203 (SD 114) v H: 112 (SD 99); p = 0.019). Immunohistochemical staining of jejunal mucosa revealed mild increase in intraepithelial CD3+ cells in D-IBS patients (D-IBS: 15.3 (SD 5.5; 95% CI 12.7 to 17.9) v H: 10.3 (SD 3.9; 95% CI 8.0 to 12.5); p = 0.006). Moreover, D-IBS patients showed marked increase in mast cells numbers (D-IBS: 34 (SD 9.3); H: 15.3 (SD 4.4) mast cells/hpf; p<0.001) and higher tryptase concentration in jejunal fluid (D-IBS: 0.45 (SD 0.38); H: 0.09 (SD 0.10) microg/l; p = 0.005). Upper gut symptoms were not associated with gender, mast cell counts, jejunal tryptase or basal stress.

CONCLUSION

This jejunal mucosal inflammatory profile may help identify diarrhoea-predominant IBS, a stress-related disorder.

Hemodynamic response-guided therapy for prevention of variceal rebleeding: an uncontrolled pilot study

The clinical usefulness of assessing hemodynamic response to drug therapy in the prophylaxis of variceal rebleeding is unknown. An open-labeled, uncontrolled pilot trial was performed to evaluate the feasibility and efficacy of using the hemodynamic response to pharmacological treatment to guide therapy in this setting. Fifty patients with acute variceal bleeding underwent a hepatic venous pressure gradient (HVPG) measurement 5 days after the episode. Nadolol and nitrates were initiated, and a second HVPG was measured 15 days later. Responder patients (> or =20% decrease in HVPG from baseline) were maintained on drugs, partial responders (> or =10% and <20%) had banding ligation added to the drugs, and nonresponders (<10%) received a transjugular intrahepatic portal-systemic shunt (TIPS). Mean follow-up was 22 months. Eight patients (16%) did not receive the second HVPG, 6 of them because of early variceal rebleeding. Of the other 42 patients, 24 were classified as responders (57%); 10 as partial responders (24%), who had banding added; and 8 as nonresponders (19%), who received a TIPS. Patients with cirrhosis of viral etiology compared to alcoholic cirrhosis tended to present more early rebleedings, less response to drugs and needed more TIPS. Variceal rebleeding occurred in 22% of all patients but only in 12% of patients whose hemodynamic response was assessed. The 3 therapeutic groups were not different. In conclusion, using hemodynamic response to pharmacological treatment to guide therapy in secondary prophylaxis to prevent variceal bleeding is feasible and effectively protects patients from rebleeding. In this context, viral cirrhosis seems to present a worse outcome than alcoholic cirrhosis.

A nationwide study of mortality associated with hospital admission due to severe gastrointestinal events and those associated with nonsteroidal antiinflammatory drug use

BACKGROUND

The worst outcome of gastrointestinal complications is death. Data regarding those associated with nonsteroidal antiinflammatory drug (NSAID) or aspirin use are scarce.

AIM

To determine mortality associated with hospital admission due to major gastrointestinal (GI) events and NSAID/aspirin use.

METHODS

The study was based on actual count of deaths from two different data sets from 2001. Study 1 was carried out in 26 general hospitals serving 7,901,198 people. Study 2 used a database from 197 general hospitals, representative of the 269 hospitals in the Spanish National Health System. Information regarding gastrointestinal complications and deaths was obtained throughout the Minimum Basic Data Set (CIE-9-MC) provided by participating hospitals. Deaths attributed to NSAID/aspirin use were estimated on the basis of prospectively collected data from hospitals of study 1.

RESULTS

The incidence of hospital admission due to major GI events of the entire (upper and lower) gastrointestinal tract was 121.9 events/100,000 persons/year, but those related to the upper GI tract were six times more frequent. Mortality rate was 5.57% (95% CI = 4.9-6.7), and 5.62% (95% CI = 4.8-6.8) in study 1 and study 2, respectively. Death rate attributed to NSAID/aspirin use was between 21.0 and 24.8 cases/million people, respectively, or 15.3 deaths/100,000 NSAID/aspirin users. Up to one-third of all NSAID/aspirin deaths can be attributed to low-dose aspirin use.

CONCLUSION

Mortality rates associated with either major upper or lower GI events are similar but upper GI events were more frequent. Deaths attributed to NSAID/ASA use were high but previous reports may have provided an overestimate and one-third of them can be due to low-dose aspirin use.

Increased plasma fibrinolytic activity in bleeding gastrointestinal angiodysplasia

OBJECTIVE

Gastrointestinal angiodysplasia is a major cause of recurrent bleeding. Haemostatic abnormalities have been implicated in the haemorrhage from these common vascular lesions but their precise contribution remains to be established. Our aim was to investigate whether bleeding angiodysplasia is associated with any specific coagulation disorder.

METHODS

Clinical features and blood samples were prospectively obtained from 21 patients with bleeding gastrointestinal angiodysplasia 3 months after the last episode of haemorrhage. Plasma levels of von Willebrand factor, D-dimer, plasminogen activator inhibitor type 1 (PAI-1), tissue-plasminogen activator activity, tissue factor pathway inhibitor and activated factor VII (FVIIa-rTF) were measured. A group of 14 patients with bleeding duodenal ulcer were similarly studied as controls.

RESULTS

Mean plasma von Willebrand factor levels were higher in angiodysplasia patients (208+/-12%) than in controls (143+/-11%) (P<0.05). D-dimer levels (661+/-80 ng/ml) and tissue-plasminogen activator activity levels (2.04+/-0.14 IU/ml) were also higher than in controls: 395+/-99 ng/ml and 1.6+/-0.1 IU/ml, respectively (P<0.05), whereas levels of PAI-1, FVIIa-rTF and tissue factor pathway inhibitor were similar in both groups. However, PAI-1 levels (31.5+/-11 ng/ml) were lower in high-bleeding-rate angiodysplasia (more than two bleeding episodes/year) than in low-bleeding-rate angiodysplasia (< or = 2 bleeding episodes/year) (PAI-1 47+/-14 ng/ml) (P<0.05). In a multivariate regression analysis, the plasma level of PAI-1 was a predictor of haemorrhage from angiodysplasia (P<0.05).

CONCLUSIONS

Increased plasma fibrinolytic activity may contribute to bleeding from angiodysplasia. Low plasma PAI-1 levels constitute a risk factor for bleeding tendency in patients with angiodysplasia.

[Massive hemorrhage due to nodular hyperplasia of Brunner's glands in antiphospholipid syndrome]

Gastrointestinal hemorrhage is an exceptional complication of antiphospholipid syndrome and most reported cases are secondary to ischemic lesions. Brunner's gland hyperplasia is an infrequent and usually asymptomatic condition that has been associated with chronic renal failure. We report a patient with primary antiphospholipid syndrome who, after mechanic heart valve replacement and while in a state of drug-induced anticoagulation, experienced a life-threatening upper gastrointestinal hemorrhage due to nodular hyperplasia of Brunner's glands. This entity may be considered in the differential diagnosis of upper gastrointestinal bleeding in patients with antiphospholipid syndrome, most of whom are treated with oral anticoagulatory drugs, and particularly in patients with chronic renal failure.

Colitis induces CRF expression in hypothalamic magnocellular neurons and blunts CRF gene response to stress in rats

We investigated hypothalamic neuronal corticotropin-releasing factor (CRF) gene expression changes in response to visceral inflammation induced by 2,4,6-trinitrobenzenesulfonic acid (TNB) and acute stress. Seven days after TNB, rats were subjected to water-avoidance stress (WAS) or restraint for 30 min and euthanized. Hypothalamic CRF primary transcripts (heteronuclear RNA, hnRNA) and CRF and arginine vasopressin (AVP) mRNAs were assessed by in situ hybridization. Antisense (35)S-labeled cRNA probes against CRF mRNA intronic and exonic sequences and an oligonucleotide probe against the AVP mRNA were used. TNB induced macroscopic lesions and a fivefold elevation in myeloperoxidase activity in the colon. Colitis increased CRF hnRNA and mRNA signals in the magnocellular part of the paraventricular nucleus of the hypothalamus (PVN) and supraoptic neurons, whereas AVP mRNA was not altered. Colitis did not modify CRF hnRNA signal in the parvocellular part of the PVN (pPVN), plasma corticosterone, and serum osmolarity levels. However, CRF hnRNA expression in the pPVN and the rise in corticosterone and defecation induced by WAS or restraint were blunted in colitic rats. These data show that colitis upregulates CRF gene synthesis in magnocellular hypothalamic neurons but dampens CRF gene transcription in the pPVN and plasma corticosterone responses to environmental acute stressors.

A multicenter, randomized, clinical trial of hormonal therapy in the prevention of rebleeding from gastrointestinal angiodysplasia

BACKGROUND & AIMS

The efficacy of hormonal therapy for recurrent bleeding from gastrointestinal angiodysplasia remains uncertain. We investigated the efficacy of long-term estrogen-progestagen therapy in the prevention of rebleeding from gastrointestinal angiodysplasia.

METHODS

Seventy-two noncirrhotic patients bleeding from gastrointestinal angiodysplasia confirmed by endoscopy or angiography were randomized to receive in double-blind conditions treatment with ethinylestradiol (0.01 mg) plus norethisterone (2 mg) (1 tablet/d), or placebo (1 tablet/d) for a minimum period of 1 year (range: 1-2 years).

RESULTS

Four patients could not be assessed because they did not attend the first follow-up visit. Failure of treatment occurred in 13 of 33 (39%) patients in the treatment group and in 16 of 35 (46%) patients in the placebo group (P = NS). No significant differences between groups were found according to number of bleeding episodes (0.7 +/- 1.0 vs. 0.9 +/- 1.5) and transfusional requirements (0.9 +/- 1.9 vs. 0.7 +/- 1.5 units). Treatment received was not an independent predictor for rebleeding prevention in the multivariate regression analysis. Severe adverse events (2 vs. 1) and mortality (0 vs. 1 patient, respectively) were similar between the treatment and placebo groups.

CONCLUSIONS

Continuous estrogen-progestagen treatment is not useful in the prevention of rebleeding from gastrointestinal angiodysplasia.

Accuracy of helical computed tomographic angiography for the diagnosis of colonic angiodysplasia

BACKGROUND & AIMS

The diagnosis of colonic angiodysplasia is often challenging and relies on endoscopy or catheter angiography. We investigated whether computed tomographic angiography (CTA) contributes to the diagnosis of colonic angiodysplasia.

METHODS

Twenty-eight patients with suspected bleeding from colonic angiodysplasia were prospectively evaluated. Gastrointestinal bleeding was investigated by colonoscopy plus visceral angiography and by CTA. The level of agreement between CTA and the former procedures was determined.

RESULTS

CTA images of diagnostic quality were obtained in 26 patients. Eighteen patients were diagnosed with colonic angiodysplasia by colonoscopy plus visceral angiography, and 14 by CTA (kappa = 0.68; P < 0.001). Sensitivity, specificity, and positive predictive values of CTA for detection of colonic angiodysplasia were 70%, 100%, and 100%, respectively. CTA signs including accumulation of vessels in the colonic wall, early filling vein, and supplying enlarged artery were present in 55%, 50%, and 22% of cases, respectively. None of these signs were present in the 8 patients with obscure gastrointestinal bleeding and negative diagnostic investigation of the digestive tract.

CONCLUSIONS

CTA is a sensitive, specific, well-tolerated, and minimally invasive tool for the diagnosis of colonic angiodysplasia.

Helicobacter pylori eradication prevents recurrence from peptic ulcer haemorrhage

BACKGROUND

Successful eradication of Helicobacter pylori infection clearly modifies the natural history of peptic ulcer disease and prevents further recurrences of duodenal and gastric ulcers. However, there are few prospective studies about actual rates of rebleeding after H. pylori eradication, a highly relevant aspect of management as re-infection, relapse of ulcer disease for other reasons (i.e. anti-inflammatory agents) or idiopathic ulcers unrelated to H. pylori may develop and cause further bleeding episodes.

OBJECTIVE

To determine the incidence of bleeding episodes after eradication of H. pylori infection in patients who had bled from an H. pylori-positive peptic ulcer.

PARTICIPANTS AND INTERVENTIONS

H. pylori-positive patients who bled from a gastric or duodenal ulcer were treated with appropriate triple and/or quadruple therapy. H. pylori eradication was confirmed by urea breath test 4 weeks after treatment. Patients received no further treatment but were followed clinically and additional urea breath tests were performed every 6 months. Endoscopy with antral and corpus biopsies and urea breath test were repeated as soon as patients manifested any dyspeptic symptoms that might signal recurrence.

RESULTS

A total of 103 patients with bleeding duodenal ulcer were included in the study; H. pylori was successfully eradicated in 93 of these patients, who were followed for a median interval of 27 months. The yearly re-infection rate was calculated to be 0.6%. There were no instances of rebleeding in any patients during the follow-up period.

CONCLUSIONS

Even after prolonged follow-up, successful H. pylori eradication prevents rebleeding.

Somatostatin plus isosorbide 5-mononitrate versus somatostatin in the control of acute gastro-oesophageal variceal bleeding: a double blind, randomised, placebo controlled clinical trial

BACKGROUND

Variceal bleeding is a severe complication of portal hypertension. Somatostatin reduces portal pressure by decreasing splanchnic blood flow, and nitrates by diminishing intrahepatic resistance. Experimental studies have shown that the combination of somatostatin and nitrates has an additive effect in decreasing portal pressure.

AIM

To compare the therapeutic efficacy of either intravenous infusion of somatostatin plus oral isosorbide 5-mononitrate or somatostatin alone in gastro-oesophageal variceal bleeding associated with liver cirrhosis.

METHODS

A unicentre, double blind, placebo controlled, clinical trial was conducted. Sixty patients bleeding from oesophageal or gastric varices were randomised to receive intravenous infusion of somatostatin (250 microg/hour) plus oral isosorbide 5-mononitrate (40 mg/12 hours) (group I) or somatostatin infusion plus placebo (group II) for 72 hours.

RESULTS

The two groups of patients had similar clinical, endoscopic, and haematological characteristics. Control of bleeding was achieved in 18 out of 30 patients (60%) in group I and 26 out of 30 patients (87%) in group II (p<0.05). There was no significant difference in mean transfusion requirements between the two groups: 2.6 (2.2) v 1.8 (1.6) respectively; means (SD). Mortality and side effects were similar in the two groups, but development of ascites was higher in group I (30%) than in group II (7%) (p<0.05).

CONCLUSION

In cirrhotic patients with acute gastro-oesophageal variceal bleeding, addition of isosorbide 5-mononitrate to somatostatin does not improve therapeutic efficacy, induces more adverse effects, and should not be used.

Characterisation of immune mediator release during the immediate response to segmental mucosal challenge in the jejunum of patients with food allergy

BACKGROUND

Food allergy is a common complaint among patients with a broad spectrum of abdominal and extra-abdominal symptoms that must be distinguished from other more common non-immunological food intolerances.

AIMS

To investigate whether human intestinal hypersensitivity reactions are associated with detectable release of inflammatory mediators from activated cells, which may serve as a biological marker of true allergic reactions.

PATIENTS/METHODS

In eight patients with food allergy and seven healthy volunteers, a closed-segment perfusion technique was used to investigate the effects of jejunal food challenge on luminal release of tryptase, histamine, prostaglandin D(2), eosinophil cationic protein, peroxidase activity, and water flux.

RESULTS

Intraluminal administration of food antigens induced a rapid increase in intestinal release of tryptase, histamine, prostaglandin D(2), and peroxidase activity (p<0.05 v basal period) but not eosinophil cationic protein. The increased release of these mediators was associated with a notable water secretory response.

CONCLUSIONS

These results suggest that human intestinal hypersensitivity reactions are characterised by prompt activation of mast cells and other immune cells, with notable and immediate secretion of water and inflammatory mediators into the intestinal lumen. Analysis of the profile of markers released into the jejunum after food provocation may be useful for the objective diagnosis of food allergy.

Mechanisms underlying the anti-inflammatory actions of central corticotropin-releasing factor

Immune activation of hypothalamic corticotropin-releasing factor (CRF) provides a negative feedback mechanism to modulate peripheral inflammatory responses. We investigated whether central CRF attenuates endothelial expression of intercellular adhesion molecule 1 (ICAM-1) and leukocyte recruitment during endotoxemia in rats and determined its mechanisms of action. As measured by intravital microscopy, lipopolysaccharide (LPS) induced a dose-dependent increase in leukocyte rolling, adhesion, and emigration in mesenteric venules, which was associated with upregulation of endothelial ICAM-1 expression. Intracisternal injection of CRF abrogated both the increased expression of ICAM-1 and leukocyte recruitment. Intravenous injection of the specific CRF receptor antagonist astressin did not modify leukocyte-endothelial cell interactions induced by a high dose of LPS but enhanced leukocyte adhesion induced by a low dose. Blockade of endogenous glucocorticoids but not alpha-melanocyte-stimulating hormone (alpha-MSH) receptors reversed the inhibitory action of CRF on leukocyte-endothelial cell interactions during endotoxemia. In conclusion, cerebral CRF blunts endothelial upregulation of ICAM-1 and attenuates the recruitment of leukocytes during endotoxemia. The anti-inflammatory effects of CRF are mediated by adrenocortical activation and additional mechanisms independent of alpha-MSH.

Increased expression of angiogenic factors in human colonic angiodysplasia

OBJECTIVE

Angiodysplasia of the colon is a distinct vascular abnormality characterized by focal accumulation of ectatic vessels in the mucosa and submucosa. To investigate whether angiogenesis contributes to the pathogenesis of human colonic angiodysplasia, we examined the expression of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), and its endothelial cell receptors flt-1 and KDR.

METHODS

Immunohistochemistry was performed in sections of specimens obtained from 18 patients with colonic angiodysplasia and from eight patients with colon cancer and its adjacent, histologically normal margins of resection. We used affinity-purified rabbit polyclonal antibodies and a streptoavidin-biotin peroxidase method.

RESULTS

We detected strong immunoreactivity for vascular endothelial growth factor, homogeneously distributed in the endothelial lining of blood vessels of all sizes in 16 (89%) specimens of colonic angiodysplasia and in seven (88%) patients with colon cancer. In contrast, very limited immunoreactivity was found in normal colon. Vascular staining for flt-1 was observed in eight (44%) and one (12.5%) of the colonic angiodysplasia or colon cancer specimens, respectively, but not in normal colon. Vascular immunoreactivity for basic fibroblast growth factor was observed in seven (39%) specimens from patients with colonic angiodysplasia, whereas either very limited or no immunostaining was found in sections from specimens of patients with colon cancer and its normal margins.

CONCLUSIONS

In human colonic angiodysplasia, increased expression of angiogenic factors is likely to play a pathogenic role.

The impact of delaying gastric emptying by either meal substrate or drug on the [13C]-urea breath test

OBJECTIVE

Optimal [13C]-urea breath test (UBT) conditions for diagnosis of Helicobacter pylori infection are still being fine-tuned. In the present study we investigated the impact of delaying gastric emptying by different meal substrates or L-DOPA, a drug known to induce gastric stasis, on the performance of the [13C]-UBT.

METHODS

A total of 115 patients participated in the study. On two consecutive days, participants ingested [13C]-urea (100 mg) 10 min after either 270 ml of a mixed formula meal (1 Kcal/ml) or an equivalent amount of tap water. In 11 participants two additional tests were performed with or without oral 500 mg L-DOPA given 30 min before [13C]-urea load. The 13C/12C ratio in a basal breath sample was compared with ratios in samples collected 30 and 60 min after [13C]-urea. Histological assessment of H. pylori presence in antral biopsy served as reference standard.

RESULTS

Formula UBT showed excellent specificity (100% at 30 and 60 min) and good sensitivity (97% at both time intervals), whereas water UBT had the same specificity but slightly lower sensitivity (94% at 30 min and 73% at 60 min). In formula UBT, 13C/12C ratios were higher at 60 min than at 30 min (21.7+/-2 vs 17.7+/-1.8 per thousand respectively, p < 0.01, whereas in water UBT 13C/12C ratios were higher at 30 min than at 60 min (13.9+/-1.5 vs 8.4+/-0.09 per thousand respectively, p < 0.01). Pretreatment with L-DOPA did not modify either the sensitivity or the specificity of the UBT.

CONCLUSIONS

The performance of the [13C]-urea with a formula meal may not be improved by pharmacologically delaying gastric emptying. A short, water-based test may be a sensible approach to worldwide standardization of the [13C]-UBT for H. pylori infection.

[The attitude of primary health care physicians in the metropolitan area of Barcelona about the diagnosis and treatment of Helicobacter pylori infection in gastroduodenal diseases]

AIM

To evaluate the attitude of primary health care physicians versus the diagnosis and treatment of infection by Helicobacter pylori in patients with dyspepsia and gastroduodenal ulcer.

DESIGN

An observational, transversal study was performed by a self administered questionnaire from June to October, 1997.

PARTICIPANTS

Primary health care physicians from 38 reformed Medical Centers in the metropolitan area of Barcelona were included in the study.

RESULTS

Of the 359 doctors to whom the questionnaire was sent, 283 responded (78.8%). In a patient with dyspepsia 95.4% would first request endoscopy. If they knew of the presence of infection by Helicobacter pylori 96.1% would administer eradication treatment in patients with gastric and duodenal ulcer and 15% would also do so if the endoscopy were normal. If the presence of infection by Helicobacter pylori were unknown in a patient with gastroduodenal ulcer, 65.3% would treat with anti-H2 or proton pump inhibitors associated with a diagnostic test of infection by Helicobacter pylori. If the physician decided to carry out eradication treatment of Helicobacter pylori infection, 98.6% would use one of the regimes recommended by different scientific societies. If confirmation of eradication of Helicobacter pylori infection were requested, 89% would do so one and three months after completion of treatment. In patients with gastric ulcer, 69.3% would request endoscopy on completion of treatment. The percentage of physicians specialized in Family and Community Medicine who would carry out eradication treatment in patients with duodenal ulcer and Helicobacter pylori infection and who would request endoscopies in patients with dyspepsia was found to be statistically significant in comparison with physicians without this specialty.

CONCLUSIONS

The attitude of primary care physicians in the metropolitan area of Barcelona with regard to the diagnosis and treatment of infection by Helicobacter pylori in gastroduodenal diseases largely reflects the recommendations recently made by several scientific societies. In general there are no significant differences with respect to this attitude in regard to the age and sex of the physician, although their training was found to influence in some of the responses analyzed.

[Gastric ulcers as the only manifestation of infection by cytomegalovirus in immunocompetent patients]

Gastritis is an infrequent manifestation of infection by cytomegalovirus (CMV) in a healthy host. This complication is usually associated to a mononucleosic syndrome during the course of a disseminated infection. Macroscopically, it presents with edema and mucosal congestion, multiple erosions or ulcers. Histologic examination of the endoscopic biopsies allows the etiologic diagnosis to be established in most cases. In immunocompetent patients the clinical course of gastritis by CMV is usually self-limited. We herein present two immunocompetent patients with gastric ulcerous disease as the only manifestation of CMV infection. Both patients required antiviral treatment due to refractoryness to the antisecretor treatment and one case evolved to pyloric stenosis requiring surgery.

Release of mast cell mediators into the jejunum by cold pain stress in humans

BACKGROUND & AIMS

The central nervous system regulates gut functions via complex interactions between the enteric nervous and immune systems. The aim of this study was to investigate whether mast cell mediators are released into the human jejunal lumen during stress.

METHODS

A closed-segment perfusion technique was used to investigate jejunal release of tryptase, histamine, prostaglandin D2, and water flux in response to the cold pressor test in 8 healthy subjects and 9 patients with food allergy. In 6 food-allergic patients, jejunal biochemical responses to cold pain stress were compared with those induced by food intraluminal challenge.

RESULTS

Cold pain stress elevated heart rate and blood pressure and increased luminal release of mast cell mediators and jejunal water secretion in both groups. Stress-induced release of tryptase and histamine, but not of prostaglandin D2 and water flux, was greater in food-allergic patients than in healthy volunteers. In food-allergic patients, jejunal biochemical responses induced by cold pain stress were similar to those induced by antigen challenge.

CONCLUSIONS

These results show the ability of the central nervous system to modulate intestinal mast cell activity and suggest that mast cells have a role in stress-related gut dysfunction.

Regulation of intestinal mast cells and luminal protein release by cerebral thyrotropin-releasing hormone in rats

BACKGROUND & AIMS

Intestinal mast cell activity is modulated by the central nervous system, but the mechanisms are not well established. The aim of this study was to investigate whether cerebral thyrotropin-releasing hormone (TRH) activates intestinal mast cells and to elucidate the mechanisms involved, specifically, the contribution of mast cells to vagally stimulated luminal protein release.

METHODS

In anesthetized rats, mast cell activation was assessed by measuring the release of the specific mucosal rat mast cell protease II (RMCP II) and prostaglandin (PG) D2 into the intestinal lumen. Luminal protein release was measured as an index of epithelial permeability to macromolecules.

RESULTS

Intracisternal injection of the TRH analogue RX 77368 (30 ng) induced a transient increase in intestinal release of RMCP II and PGD2 that was abolished by dox-antrazole. RX 77368-stimulated RMCP II release was also abolished by vagotomy and reduced by atropine by 65%. However, both systemic capsaicin and indo-methacin enhanced RMCP II release. RX 77368-stimulated luminal protein release was abolished by vagotomy and reduced by doxantrazole.

CONCLUSIONS

Central vagal activation by TRH stimulates intestinal mast cell secretion, in part via peripheral muscarinic receptors, and is modulated by PGs and capsaicin-sensitive afferent innervation. Intestinal mast cell activation contributes to the TRH analogue-stimulated luminal protein release.

Central vagal activation by an analogue of TRH stimulates gastric nitric oxide release in rats

In the stomach nitric oxide (NO) appears to be involved in vagally induced cholinergic vasodilation and nonadrenergic, noncholinergic relaxation of the fundus. We investigated whether central vagal activation by intracisternal injection of a thyrotropin-releasing hormone (TRH) analogue stimulates gastric NO release in anesthetized rats. To quantitate gastric NO production, the luminal release of NO breakdown products, nitrite (NO2-) and nitrate (NO3-), were measured by the Griess method. Intracisternal injection of RX-77368 (30-300 ng) dose dependently stimulated gastric NO2- and NO3- release (P < 0.05) along with a significant acid secretory response (P < 0.05). The specific inhibitor of NO synthesis, NG-nitro-L-arginine methyl ester (10 mg/kg ip), completely blocked gastric luminal NO2- and NO3- release without affecting the acid secretory response to the highest dose of RX-77368. Either bilateral cervical vagotomy, hexamethonium (15 mg/kg ip), or atropine (1 mg/kg ip) abolished both gastric luminal release of NO-derived metabolites and the acid secretory responses to RX-77368. These results indicate that intracisternal injection of RX-77368 stimulates gastric release of NO through vagal nicotinic pathways and peripheral activation of muscarinic receptors. These findings provide evidence for central nervous system regulation of NO-mediated functions in the rat stomach through TRH-sensitive vagal pathways.

[Estrogen and progestagen treatment in digestive hemorrhage caused by vascular malformations]

The efficacy of an association of estrogens and progestagens in the treatment of gastrointestinal bleeding by angiodysplasia was analyzed. Thirty-three patients with gastrointestinal bleeding due to vascular malformations were admitted from January 1986 to December 1993. Fifteen of the 33 patients were submitted to surgical or endoscopic treatment. The remaining 18 patients underwent daily oral treatment with a combination of estrogens-progestagens containing 2.5 mg of lynestrenol and 0.075 mg of mestranol. One patient presented a venous thrombosis leading to suppression of treatment at one month of initiation. The 17 remaining patients were treated for a mean of 22 +/- 4 months (range: 3-60). During treatment 13 of the 17 patients (76%) did not present evidence of hemorrhage. Likewise, the number of hemorrhagic episodes per year decreased from 4.4 +/- 1.2 prior to treatment to 0.7 +/- 0.5 during treatment (p < 0.05) with transfusional requirements decreasing from 7.9 +/- 2.8 erythrocyte concentrates per year prior to treatment to 1.2 +/- 1.0 during treatment (p < 0.05). In conclusion, the combined treatment with estrogens and progestagens prevents recurrence of gastrointestinal bleeding by angiodysplasia.