Colonic gas homeostasis: Mechanisms of adaptation following HOST-G904 galactooligosaccharide use in humans.

BACKGROUND: We have shown that a galactooligosaccharide prebiotic administration (HOST-G904) initially increased intestinal gas production and this increase declined back to baseline after 2 week administration. Our aim was to determine the mechanism of microbiota adaptation; i.e., to determine whether the net reduction is due to decreased overall production or increased gas consumption. METHODS: In 10 healthy subjects, intestinal gas production and intraluminal disposal was measured before, at the beginning and after 2 week of HOST-G904 prebiotic administration. Anal gas was collected for 4 hour after a probe meal. Paired studies were performed without and with high-rate infusion of exogenous gas (24 mL/min) into the jejunum to wash-out the endogenous gas produced by bacterial fermentation. The exogenous gas infused was labeled (5% SF6 ) to calculate the proportion of endogenous gas evacuated. KEY RESULTS: The volume of intestinal gas produced i.e., endogenous gas washed-out, increased by 37% at the beginning of HOST-G904 administration (P=.049 vs preadministration) and decreased down to preadministration level after 2 week administration (P=.030 vs early administration). The proportion of gas eliminated from the lumen before reaching the anus tended to increase after 2-week administration (87±3% vs 78±5% preadministration; P=.098). CONCLUSIONS & INFERENCES: Adaptation to regular consumption of HOST-G904 prebiotic involves a shift in microbiota metabolism toward low-gas producing pathways, with a non-significant increase in gas-consuming activity. Hence, regular consumption of HOST-G904 regulates intestinal gas metabolism: less gas is produced and a somewhat larger proportion of it is consumed.

Effect of inulin and fructo-oligosaccharide on the prevention of acute radiation enteritis in patients with gynecological cancer and impact on quality-of-life: a randomized, double-blind, placebo-controlled trial.

BACKGROUND/OBJECTIVES: The pathogenesis of enteritis after abdominal radiotherapy (RT) is unknown, although changes in fecal microbiota may be involved. Prebiotics stimulate the proliferation of Lactobacillus spp and Bifidobacterium spp, and this may have positive effects on the intestinal mucosa during abdominal RT. SUBJECTS/METHODS: We performed a randomized, double-blind, placebo-controlled trial involving patients with gynecological cancer who received abdominal RT after surgery. Patients were randomized to receive prebiotics or placebo. The prebiotic group received a mixture of fiber (50 inulin and 50% fructo-oligosaccharide), and the placebo group received 6 g of maltodextrin twice daily from 1 week before to 3 weeks after RT. The number of bowel movements and stool consistency was recorded daily. Diarrhea was evaluated according to the Common Toxicity Criteria of the National Cancer Institute. Stool consistency was assessed using the 7-point Bristol scale. Patients' quality-of-life was evaluated at baseline and at completion of RT using the EORTC-QLQ-C30 (European Organization for Research and Treatment of Cancer quality-of-life Questionnaire C30) test. RESULTS: Thirty-eight women with a mean age of 60.3±11.8 years participated in the study. Both groups (prebiotic (n=20) and placebo (n=18)) were comparable in their baseline characteristics. The number of bowel movements per month increased in both groups during RT. The number of bowel movements per day increased in both groups. The number of days with watery stool (Bristol score 7) was lower in the prebiotic group (3.3±4.4 to 2.2±1.6) than in the placebo group (P=0.08). With respect to quality-of-life, the symptoms with the highest score in the placebo group were insomnia at baseline and diarrhea toward the end of the treatment. In the prebiotic group, insomnia was the symptom with the highest score at both assessments, although the differences were not statistically significant. CONCLUSIONS: Prebiotics can improve the consistency of stools in gynecologic cancer patients on RT. This finding could have important implications in the quality-of-life of these patients during treatment.

Accumulative effect of food residues on intestinal gas production.

BACKGROUND: As mean transit time in the colon is longer than the interval between meals, several consecutive meal loads accumulate, and contribute to colonic biomass. Our aim was to determine the summation effect of fermentable food residues on intestinal gas production. METHODS: In eight healthy subjects, the volume of endogenous intestinal gas produced in the intestine over a 4-h period was measured by means of a wash-out technique, using an exogenous gas infusion into the jejunum (24 mL/min) and collection of the effluent via a rectal Foley catheter. The exogenous gas infused was labeled (5% SF6 ) to calculate the proportion of endogenous intestinal gas evacuated. In each subject, four experiments were performed ≥1 week apart combining a 1-day high- or low-flatulogenic diet with a test meal or fast. KEY RESULTS: Basal conditions: on the low-flatulogenic diet, intestinal gas production during fasting over the 4-h study period was 609 ± 63 mL. Effect of diet: during fasting, intestinal gas production on the high-flatulogenic diet was 370 ± 146 mL greater than on the low-flatulogenic diet (p = 0.040). Effect of test meal: on the low-flatulogenic diet, intestinal gas production after the test meal was 681 ± 114 mL greater than during fasting (p = 0.001); a similar effect was observed on the high-flatulogenic diet (599 ± 174 mL more intestinal gas production after the test meal than during fasting; p = 0.021). CONCLUSIONS & INFERENCES: Our data demonstrate temporal summation effects of food residues on intestinal gas production. Hence, intestinal gas production depends on pre-existing and on recent colonic loads of fermentable foodstuffs.

The administration of probiotics and synbiotics in immune compromised adults: is it safe?

This study aimed to systematically evaluate safety of probiotics and synbiotics in immune compromised adults (≥18 years). Safety was analysed using the Common Terminology Clinical Adverse Events (CTCAE version 4.0) classification, thereby providing an update on previous reports using the most recent available clinical data (2008-2013). Safety aspects are represented and related to number of participants per probiotic strain/culture, study duration, dosage, clinical condition and selected afflictions. Analysis of 57 clinical studies indicates that probiotic and/or synbiotic administration in immune compromised adults is safe with regard to the current evaluated probiotic strains, dosages and duration. Individuals were considered immune compromised if HIV-infected, critically ill, underwent surgery or had an organ- or an autoimmune disease. There were no major safety concerns in the study, as none of the serious adverse events (AE)s were related, or suspected to be related, to the probiotic or synbiotic product and the study products were well tolerated. Overall, AEs occurred less frequent in immune compromised subjects receiving probiotics and/or synbiotics compared to the control group. In addition, the results demonstrated a flaw in precise reporting and classification of AE in most studies. Furthermore, generalisability of conclusions are greatly limited by the inconsistent, imprecise and potentially incomplete reporting as well as the variation in probiotic strains, dosages, administration regimes, study populations and reported outcomes. We argue that standardised reporting on adverse events (CTCAE) in 'food' studies should be obligatory, thereby improving reliability of data and re-enforcing the safety profile of probiotics.

Effect of a mixture of inulin and fructo-oligosaccharide on Lactobacillus and Bifidobacterium intestinal microbiota of patients receiving radiotherapy: a randomised, double-blind, placebo-controlled trial.

BACKGROUND & AIMS: The pathogenesis of enteritis after abdominal radiotherapy is unknown, although changes in faecal microbiota may be involved. In several studies, Lactobacillus and Bifidobacterium have proven beneficial for the host. Prebiotics stimulate the proliferation of Lactobacillus and Bifidobacterium, and this may have positive effects on the intestinal mucosa during abdominal radiotherapy. METHODS: We performed a randomised double-blind, placebo-controlled trial including 31 patients with gynaecological cancer who received radiotherapy (29 sessions, 52.2 Gy) after surgery. Patients were randomised to two groups: prebiotic and placebo. The first group received a mixture of fibre (50% inulin and 50% fructo-oligosaccharide) and the second received 6 g of maltodextrin twice daily from one week before to three weeks after radiotherapy. Lactobacillus and Bifidobacterium counts were determined in faeces samples (day -7 before radiotherapy, day 15 of radiotherapy, at the end of treatment, and three weeks after radiotherapy) by culture in selective media and fluorescent in situ hybridization (FISH) using genus-specific probes. Bacterial counts by FISH were significantly higher than by culture method. RESULTS: There were no differences in baseline microbiota between groups. At the end of radiotherapy, we observed a statistically significant decrease in Lactobacillus and Bifidobacterium counts in both groups. By cultural analysis, we observed higher numbers of Lactobacillus and Bifidobacterium three weeks after radiotherapy in the prebiotic group (5.6 vs. 6.3, p = 0.04 and 5.5 vs. 6 log cfu/g, p = 0.03). CONCLUSIONS: Abdominal radiotherapy negatively affects Lactobacillus and Bifidobacterium counts. The prebiotic mixture of inulin and fructoligosaccharide can improve the recovery of both genera after radiotherapy. Registered under ClinicalTrials.gov Identifier no. NCT01549782.

Cutoff values of the Inflammatory Bowel Disease Questionnaire to predict a normal health related quality of life.

UNLABELLED: One of the objectives in the treatment of the inflammatory bowel disease (IBD) is improving the patient's quality of life. However, we do not dispose of validated criteria to determine the questionnaire's scoring threshold that has to be reached in order to be able to assert that the patients' quality of life has normalized. OBJECTIVE: To determine the normality punctuation cutoff in the IBD specific quality of life questionnaire IBDQ-36. METHOD: Cross-sectional study in a random sample of IBD patients, who have completed the questionnaires IBDQ-36 and EuroQol-5D. The IBDQ-36 normality was calculated according to its equivalence with the EuroQol-5D tariff ≥ 0.90, which corresponds to the 95% CI of the average obtained in a Spanish general population. RESULTS: 218 patients were included. According to the EuroQol-5D tariff, 70 patients were considered to have a normal quality of life and 148 a quality of life poorer than the general population. The IBDQ-36 scoring was significantly higher in the normal quality of life group (222.9 ± 22.8 vs. 171.4 ± 44.8 in the bad quality of life group, p<0.001). According to the linear regression between IBDQ-36 and EuroQol-5D, the cutoff point is 209, with a sensitivity and specificity to predict normality of 0.74 and 0.71 respectively. CONCLUSIONS: Scores of the IBDQ-36 equal or superior to 209 suggest quality of life comparable to that perceived by the general population. This study allowed to set a threshold of normality in the management of the inflammatory bowel diseases.

Faecal DNA and calprotectin as biomarkers of acute intestinal toxicity in patients undergoing pelvic radiotherapy.

BACKGROUND: Acute intestinal toxicity is a frequent complication that may lead to interruption of treatment in patients undergoing pelvic radiotherapy. Reliable, non-invasive biological markers to evidence their severity are not yet available. AIM: To test faecal DNA and calprotectin as potential biomarkers of intestinal toxicity caused by pelvic radiotherapy. METHODS: Patients were categorized according to the location of the cancer as nonrectal (n = 25) and rectal (n = 27). Four stool samples were collected at weeks w0, w3, w5 (end of radiotherapy) and w7. Faecal DNA was determined by quantitative PCR and calprotectin by ELISA. Intestinal toxicity was scored according to the Common Toxicity Criteria. RESULTS: In the nonrectal group, acute diarrhoea toxicity was present in 80% of patients, faecal DNA increased 10-fold during radiotherapy (1.5 x 10(3) copies/mg dry weight, 9.5 x 10(2)-8.8 x 10(3) at w0, median and interquartile range vs. 1.3 x 10(4), 1.9 x 10(3)-3.9 x 10(4) at w5, P < 0.01), but was not recovered at w7 (3.4 x 10(3), 1.5 x 10(3)-4.1 x 10(4)) and calprotectin doubled during treatment at w3 and w5. No significant changes in faecal markers were found in the rectal group. CONCLUSION: Faecal excretion of human DNA and calprotectin increased during pelvic radiotherapy treatment, and may be a good objective biomarker of intestinal damage in nonrectal cancer patients.

Selective inhibition of phosphodiesterase-4 ameliorates chronic colitis and prevents intestinal fibrosis.

The phosphodiesterase-4 (PDE4) inhibitors may be an important target in the treatment of several inflammatory conditions. The anti-inflammatory effect of PDE4 inhibitors bears similarities with that of steroids, without interfering with the hypophysary-adrenal-axis. We compared the effect of rolipram, a selective PDE4 inhibitor, with steroids on the clinical course of experimental colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS). Three groups of rats (n = 20) received TNBS. One group received methylprednisolone from day 7, another group received rolipram from the same day, and control group received no further treatment. On days 14 and 21 after TNBS instillation, sets of 10 rats underwent colonic dialysis to measure eicosanoid release. Colonic lesions were blindly scored, and colons were homogenized for quantification of myeloperoxidase (MPO) activity and collagen content. Concentration of tumor necrosis factor alpha (TNF-alpha) and transforming growth factor beta1 (TGF-beta1) in colonic tissue was also measured. Both treatments reduced significantly the eicosanoid release and MPO activity. On day 14, both rolipram and methylprednisolone significantly reduced TNF-alpha content, but TGF-beta1 was only inhibited by rolipram. On day 21, lesion scores and collagen content were significantly reduced only in rolipram-treated group. In conclusion, PDE4 inhibition by rolipram markedly ameliorates the course of chronic colitis and it is superior to methylprednisolone in preventing late collagen deposition.

Probiotics and human health: a clinical perspective.

There is unequivocal evidence that administration of probiotics could be effective in the treatment of acute infectious diarrhoea in children and the prevention of antibiotic associated diarrhoea and nosocomial/community acquired diarrhoea. Encouraging evidence is also emerging for the effectiveness of probiotics in the prevention and management of pouchitis and paediatric atopic diseases, and the prevention of postoperative infections. There is also strong evidence that certain probiotic strains are able to enhance immune function, especially in subjects with less than adequate immune function such as the elderly. Efficacy of probiotics in the prevention of traveller's diarrhoea, sepsis associated with severe acute pancreatitis, and cancers, the management of ulcerative colitis, and lowering of blood cholesterol remains unproven. In addition to firm evidence of efficacy (for a range of conditions), major gaps exist in our knowledge regarding the mechanisms by which probiotics modulate various physiological functions and the optimum dose, frequency, and duration of treatment for different probiotic strains.

Increased mucosal tumour necrosis factor alpha production in Crohn's disease can be downregulated ex vivo by probiotic bacteria.

BACKGROUND AND AIMS: Tumour necrosis factor alpha (TNF-alpha) plays a key role in the pathogenesis of intestinal inflammation in Crohn's disease. The effect of bacteria on TNF-alpha release by intestinal mucosa was investigated. METHODS: Ileal specimens were obtained at surgery from 10 patients with Crohn's disease (ileal stricture) and five disease controls undergoing right hemicolectomy (caecal cancer). Mucosal explants from each specimen were cultured for 24 hours with either non-pathogenic Escherichia coli, Lactobacillus casei DN-114001, L bulgaricus LB10, or L crispatus (each study contained blank wells with no bacteria). Tissue and bacterial viability was confirmed by lactate dehydrogenase (LDH) release and culture. Concentrations of TNF-alpha were measured in supernatants and the phenotype of the intestinal lymphocytes was analysed by flow cytometry. RESULTS: Coculture of mucosa with bacteria did not modify LDH release. Release of TNF-alpha by inflamed Crohn's disease mucosa was significantly reduced by coculture with L casei or L bulgaricus; changes induced by L crispatus or E coli were not significant. The effect of L casei and L bulgaricus was not prevented by protease inhibitors. Coculture with L casei and L bulgaricus reduced the number of CD4 cells as well as TNF-alpha expression among intraepithelial lymphocytes from Crohn's disease mucosa. None of the bacteria induced changes in non-inflamed mucosa. CONCLUSIONS: Probiotics interact with immunocompetent cells using the mucosal interface and modulate locally the production of proinflammatory cytokines.

Antitumor necrosis factor therapy in rat chronic granulomatous colitis: critical dose-timing effects on outcome.

Inhibition of tumor necrosis fact (TNFalpha) is of potential benefit in the treatment of chronic inflammatory conditions. However, TNFalpha plays an important role in host defenses against infection, and blocking TNFalpha production may also have adverse effects. We tested the efficacy and safety of anti-TNFalpha therapy in experimental colitis induced by trinitrobenzenesulfonic acid. We cultured colonic wall specimens for bacterial growth and measured native TNFalpha protein synthesis in colonic tissue at days 0, 1, 4, 10 and 18 after induction of colitis. Anti-TNFalpha therapy (monoclonal g1 immunoglobulin, 15 mg/kg i.p., every third day) was started on either day 4 or day 10 after induction of colitis. On day 18, we measured the release of inflammatory mediators and scored colonic lesions. In acute lesions, several species of the common flora were grown, including Streptococcus, Staphylococcus, Bacteroides, clostridia and enterobacteria. In chronic lesions, only enterobacteria, clostridia and lactobacilli were isolated. TNFalpha production by inflamed colonic tissue was increased in both acute and chronic lesions. Anti-TNFalpha therapy induced a significant decrease in the release of inflammatory mediators and histopathological remission when treatment started on day 10. However, anti-TNFalpha therapy increased eicosanoid release and lesion scores when treatment started on day 4. In conclusion, acute colonic lesions showed polymicrobial infection. Anti-TNFalpha therapy induced remission of chronic intestinal inflammation, but early treatment did not prove effective.

Stimulation of transforming growth factor beta1 by enteric bacteria in the pathogenesis of rat intestinal fibrosis.

BACKGROUND & AIMS: Bacteria and their products stimulate inflammatory responses. Certain mediators, such as transforming growth factor beta1 (TGF-beta1), induce collagen synthesis. Excess collagen deposition results in bowel strictures. The aim of this study was to investigate the role of bacteria and TGF-beta1 in the pathogenesis of intestinal fibrosis. METHODS: In rats with colitis, the effects of bowel decontamination with antibiotics on TGF-beta1, tumor necrosis factor alpha (TNF-alpha), and collagen content in colonic tissue were studied. In normal rats, bacteria of the predominant flora were inoculated into the colonic wall. The effect of neutralizing antibody to TGF-beta1 on tissue collagen deposition was studied. RESULTS: Rats with chronic colitis showed increased levels of TGF-beta1, TNF-alpha, and collagen in the tissue and a high rate of bowel strictures. Antibiotic treatment significantly prevented the increase in TGF-beta1 and collagen and the formation of strictures. Inoculation of bacterial suspensions into the colonic wall increased tissue TGF-beta1 and collagen content. Neutralizing antibody to TGF-beta1 prevented collagen deposition. Colonic wall inoculations with single anaerobic strains (Clostridium ramosum, Bacteroides fragilis, and Bacteroides uniformis), but not with aerobes, induced collagen deposition. CONCLUSIONS: Certain strains of the common flora stimulate TGF-beta1 and induce deposition of collagen in the colonic wall.

Induction of nitric oxide synthase in colonic smooth muscle from patients with toxic megacolon.

BACKGROUND & AIMS: Colonic inflammation may lead to motility disturbances, including severe atony. Nitric oxide is released by inflamed tissue and induces smooth muscle relaxation. The aim of this study was to analyze NO generation pathways in colonic tissue from patients who had ulcerative colitis with or without toxic megacolon and in tumor-free samples from patients with colonic neoplasm. METHODS: Enzymatic activity was determined by transformation of [14C]arginine to [14C]citrulline in mucosa and muscular layer samples. Immunostaining of tissue sections with antibody against inducible NO synthase was investigated. The effects of endotoxin on NO synthase activity was tested in muscle strips from human colon. RESULTS: Ca(2+)-independent NO synthase was undetectable or very low in muscularis propria from tumor and colitis controls. In contrast, specimens from patients with toxic megacolon had high activity (P < 0.05). Positive immunostaining for inducible NO synthase was found in muscular layers from patients with megacolon but not in tumor and colitis controls. Finally, endotoxin induced Ca(2+)-independent NO synthase activity in colonic muscle. CONCLUSIONS: Toxic megacolon is associated with the appearance of inducible NO synthase in the colonic muscularis propria. Local generation of excessive amounts of NO may be responsible for the colonic dilatation that is the hallmark of this syndrome.

Intraluminal colonic release of immunoreactive tumour necrosis factor in chronic ulcerative colitis.

1. Tumour necrosis factor is a proinflammatory macrophage-derived polypeptide cytokine. Its participation in disease processes has been usually inferred from data obtained from experiments in vitro or from measurements of its plasma circulating levels. To investigate its role in chronic ulcerative colitis, we have quantified in vivo the steady-state release of tumour necrosis factor into the colonic lumen. 2. We studied 19 patients with untreated active ulcerative colitis and seven patients with irritable bowel syndrome as controls. A group of seven patients with active ulcerative colitis were studied before and after 4 weeks on treatment with oral 5-aminosalicylic acid. By means of an intracolonic double-lumen perfusion tube, an isotonic solution was continuously infused 50 cm from the anal verge at a rate of 5 ml/min, and was recovered 30 cm distally by siphonage. Effluents were assayed for tumour necrosis factor by a specific e.l.i.s.a. and for prostaglandin E2 and leukotriene B4 by specific r.i.a.s. 3. The intracolonic release of tumour necrosis factor was undetectable in patients with irritable bowel syndrome, whereas measurable release occurred in 15 out of 19 patients with active ulcerative colitis (P < 0.01). Prostaglandin E2 and leukotriene B4 release were also increased in active ulcerative colitis by comparison with irritable bowel syndrome (P < 0.01). Five out of seven patients with colitis improved with 5-aminosalicylic acid treatment, and tumour necrosis factor release became undetectable or decreased markedly (P < 0.05 compared with before treatment). However, tumour necrosis factor release remained high in the non-responder patients. 4. These findings indicate that intracolonic immunoreactive tumour necrosis factor release is enhanced in active chronic ulcerative colitis, becoming undetectable when mucosal lesions are healed. These results suggest that the luminal release of tumour necrosis factor may serve as an objective index of inflammatory activity in patients with chronic ulcerative colitis.

Role of intestinal microflora in chronic inflammation and ulceration of the rat colon.

Bacteria and their products stimulate inflammatory responses. The effects of different antimicrobial regimens (amoxicillin/clavulanic acid, tobramycin, imipenem, vancomycin, metronidazole) were investigated on the course of experimental colitis induced by trinitrobenzenesulphonic acid (TNB) in the rat. On day 7 and 21 after the induction of colitis, matched groups of control and antibiotic treated rats were subjected to colonic dialysis to measure eicosanoid release, and killed for morphological assessment of the colonic lesions (macro and microscopic scores). Stool samples were cultured. Selective antibiotic treatment against Gram positive, Gram negative or anaerobic bacteria had no effect on colonic lesion scores. By contrast, certain broad spectrum antibiotics (amoxicillin/clavulanic acid or the association of imipenem plus vancomycin) significantly reduced macro and microscopic scores. Rats receiving these antibiotics did not develop chronic colitis as shown by the virtual absence of colonic strictures, adhesions, fibrosis, and granulomas. On day 21 after TNB, the intracolonic release of prostaglandin E2, thromboxane B2, and leukotriene B4 was significantly higher in control than in antibiotic treated rats. Control stool cultures showed abundant colony forming units of both aerobic and anaerobic bacteria. Amoxicillin/clavulanic acid and imipenem plus vancomycin induced appreciable reductions in luminal bacteria. In conclusion, certain broad spectrum antibiotics prevent chronic colitis. The normal colonic flora seems to play an important pathogenetic part in the progression of inflammatory colonic lesions to chronicity.

[Nitric oxide and Hirschsprung's disease: a causal relation biochemically, immunohistochemically and functionally demonstrated]. / Oxido nítrico y enfermedad de Hirschsprung: relación causal demostrada bioquímica, inmunohistoquímica y funcionalmente.

UNLABELLED: Hirschsprung's disease may be due to impaired nonadrenergic-noncholinergic inhibitory input in the aganglionic segment of the colon. It has been suggested that nitric oxide (NO) might be the lacking neurotransmitter. Thus, our specific aims were to determine in ganglionic and aganglionic segments: 1. The activity of the NO synthetase (NO-S); 2. The location of this enzyme; and 3. The "in vitro" basal motor activity of the muscle strips and their responses to an NO donor and to an NO antagonist. METHODS: NO synthetase activity was quantified in samples of tissue from both aganglionic and ganglionic segments obtained during surgery in 6 patients with Hirschsprung's disease by the transformation of 14C-L-arginine into 14C-L-citrulline in tissue homogenates. Immunohistochemical staining of the tissues was performed using a polyclonal antibody raised against a peptide sequence of rat brain NO synthetase. Furthermore, in 2 patients we measured "in vitro" the tonic response of muscle strips to an exogenous NO donor (sodium nitroprusside) and to an NO antagonist (L-NAME). RESULTS: NOS activity was undetectable in every aganglionic segment whereas it was present in all ganglionic segments (0.49 +/- 0.09 pmol citrulina/mg.min; mean +/- SE). Immunohistochemically, NO-S was absent in the myenteric plexus of aganglionic segments and it was present in ganglionic segments. "In vitro" basal motor activity of ganglionic segments was normal, with presence of low-frequency contractions (LFC) and summation contraction (SC); in aganglionic segments SC were absent. Sodium nitroprusside induced a marked relaxation (90% from basal) in muscle strips, both aganglionic and ganglionic, precontracted with bethanocol.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormal leukotriene C4 released by unaffected jejunal mucosa in patients with inactive Crohn's disease.

The mucosal release of inflammatory mediators is enhanced in active inflammatory bowel disease. This study examines whether leukotriene C4 production occurs in apparently unaffected segments of the gut. The intraluminal release of leukotriene C4 was determined by jejunal perfusion in seven healthy controls, in nine patients with chronic ulcerative colitis, and in 13 patients with Crohn's disease (six with ileal disease, and seven with only colonic). All patients were in clinical remission and none of them had evidence of jejunal involvement. Mild intraluminal irritation with a 2.5 mmol/l deoxycholic acid solution was induced to stimulate local inflammatory mechanisms. The release of DNA (a marker of mucosal desquamation) and prostaglandin E2 (PGE2) was simultaneously measured. Jejunal release of DNA was higher in Crohn's disease patients than in ulcerative colitis or healthy controls. Basal release of PGE2 was similar in the three groups of patients. Basal release of leukotriene C4 was considerably enhanced, however, in Crohn's disease patients compared with healthy controls. In ulcerative colitis patients, basal leukotriene C4 release was non-significantly different from controls. Bile acid perfusion stimulated PGE2, leukotriene C4, and DNA release in all groups studied, but leukotriene C4 release was significantly higher in Crohn's disease patients. It is concluded that in inactive Crohn's disease there is an enhanced intraluminal release of leukotriene C4 in apparently unaffected segments of proximal small bowel, which may reflect fundamental changes in the function of the gut mucosal barrier.

Patients with achalasia lack nitric oxide synthase in the gastro-oesophageal junction.

The abnormal function of the lower oesophageal sphincter in achalasia is likely to be due to impaired nonadrenergic, noncholinergic (NANC) inhibitory input. Since recent studies in animals suggest that nitric oxide (NO) is implicated physiologically in the inhibitory responses of the lower oesophageal sphincter, we have investigated whether the synthesis of NO is altered in the gastro-oesophageal junction of patients with achalasia. NO synthase activity was investigated in samples of tissue from the gastro-oesophageal junction obtained during surgery in eight patients with typical achalasia and six non-achalasic controls who underwent oesophagectomy for reasons other than sphincter dysfunction. The NO synthase activity was determined by the transformation of 14C-L-arginine into 14C-L-citrulline in tissue homogenates. In addition, immunohistochemical staining of the tissues was performed using a polyclonal antibody raised against a peptide sequence of rat brain NO synthase. Furthermore, the relaxant response to an exogenous NO donor (sodium nitroprusside, SNP) was measured in vitro in muscle strips obtained from two patients with achalasia and in two non-achalasic controls. NO synthase activity was detected in each of the samples obtained from six control patients (0.59 +/- 0.21 pmol mg-1 min-1; mean +/- SE). By contrast, none of the samples obtained from the eight patients with achalasia had any detectable NO synthase activity. Immunohistochemical studies confirmed the presence of NO synthase in the myenteric plexus of the gastro-oesophageal junction of control patients and its absence in achalasia. SNP relaxed muscle strips precontracted with bethanechol in both control samples and those from patients with achalasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary manipulation in experimental inflammatory bowel disease.

Eicosanoids are major mediators of defensive and inflammatory processes of the gut mucosa. The activity of the eicosanoid system is modulated by neural and hormonal pathways, but local factors acting within the gastrointestinal lumen may also be involved. We have studied the influence of dietary fatty acids on eicosanoid synthesis by the gastrointestinal mucosa. Since omega-3 fatty acids compete with the omega-6 as precursors of eicosanoid synthesis, we compared the effects of dietary supplementation with either sunflower or cod liver oil as sources of omega-6 or omega-3 fatty acids, respectively. Rats fed with the cod-liver-oil-supplemented diet for four weeks showed high omega-3 and low omega-6 plasma fatty acid levels compared to rats fed with the sunflower oil diet. Synthesis of arachidonic-acid-derived eicosanoids (6-keto-PGF1 alpha, PGE2, TXB2, LTB4, and LTC4) by gastric and intestinal mucosa was found to be lower in the cod liver group as compared to the sunflower group. However, significant generation of eicosapentaenoic-acid-derived eicosanoids (PGE3 and LTC5) was observed only in the cod liver group. We used the (trinitrobenzenesulphonic acid) TNBS model of inflammatory colitis to test the effect of the dietary fat on the development of inflammatory lesions of the bowel. A single intracolonic instillation of the hapten TNBS dissolved in 10% ethanol induces chronic granulomatous lesions of the colonic mucosa that persist for up to 8 weeks. Luminal release of eicosanoid mediators, as measured by intracolonic dialysis, was lower in the cod liver group than in the sunflower group, particularly during the chronic stage of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic prostacyclin in cirrhotic patients. Relationship with portal hypertension and changes after intestinal decontamination.

The total body production of prostacyclin was shown to be increased in cirrhotic patients, suggesting that its synthesis by blood vessels of the systemic circulation is enhanced. However, the mechanism by which the synthesis of systemic prostacyclin is stimulated is not known. The present study investigated the urinary excretion of 2,3-dinor-6-keto-PGF1 alpha, an index of total body prostacyclin synthesis, first, in cirrhotics with portal hypertension (n = 19) as compared with cirrhotics with reduced portal pressure after portacaval shunt surgery (n = 18) and with control noncirrhotic subjects (n = 11), and; second, in cirrhotics before and after intestinal decontamination by oral nonabsorbable antibiotics (n = 9 antibiotic treated patients, n = 10 control nontreated cirrhotics). Control noncirrhotic subjects showed lower urinary excretion of 2,3-dinor-6-keto-PGF1 alpha than both groups of cirrhotics (P less than 0.001). Interestingly, urinary excretion of 2,3-dinor-6-keto-PGF1 alpha was significantly higher in cirrhotics with portacaval shunt than in those with portal hypertension (P less than 0.01). The urinary excretion of 2,3-dinor-6-keto-PGF1 alpha decreased significantly after intestinal decontamination in the antibiotic-treated group (580.1 +/- 232.4 vs. 431.2 +/- 219.2 pg/mg creatinine; P less than 0.05) but not in nontreated patients (543.9 +/- 214.4 vs. 581.2 +/- 281.4 pg/mg creatinine; P = NS). These data suggest that the increased urinary excretion of 2,3-dinor-6-keto-PGF1 alpha observed in cirrhotics is not directly related to portal hypertension itself but to portal blood factors that bypass the liver. Some such factors may be of intestinal bacterial origin.