Do horses suffer from irritable bowel syndrome?

Irritable bowel syndrome (IBS) in man is not a single entity but has several causes. One of the most common forms has similarities with colic and laminitis in horses. Undigested food residues may pass from the small intestine into the colon where bacterial fermentation produces chemicals that lead to disease. In horses the consequences may be disastrous, but in healthy humans such malabsorption may not be harmful. After events such as bacterial gastroenteritis or antibiotic treatment, an imbalance of the colonic microflora with overgrowth of facultative anaerobes may arise, leading to malfermentation and IBS. It is not known whether such subtle changes may likewise be present in the microflora of horses who are susceptible to colic and laminitis. Metabolomic studies of urine and faeces may provide a suitable way forward to identify such changes in the horse's gut and thus help to identify more accurately those at risk and to provide opportunities for the development of improved treatment.

Differences in microbial metabolites in urine headspace of subjects with Immune Thrombocytopenia (ITP) detected by volatile organic compound (VOC) analysis and metabolomics.

ITP is an organ-specific autoimmune disorder characterised by a low platelet count whose cause is uncertain. A possible factor is food intolerance, although much of the information linking this with ITP is anecdotal. The role of food intolerance in ITP was studied by replacing a normal diet with an elemental diet (E028), but this did not increase platelet counts. Clear differences, however, were apparent between the volatile organic compounds (VOCs) in the urine headspace of patients with ITP and those present in healthy volunteers, which leads to speculation that abnormal metabolic activity of the intestinal microbiome may be a factor causing ITP. However, further work is needed to confirm this. There were also differences between the VOCs of patients on a normal diet and those on the elemental diet, and in this case, the VOCs involved are very likely to be of bacterial origin, as their production is affected by dietary manipulation. Many of these VOCs are known to be toxic.

Enteral feeding reduces metabolic activity of the intestinal microbiome in Crohn's disease: an observational study.

BACKGROUND/OBJECTIVES: Enteral feeding will induce remission in as many as 80-90% of compliant patients with active Crohn's disease (CD), but its method of action remains uncertain. This study was designed to examine its effects on the colonic microbiome. METHODS/SUBJECTS: Healthy volunteers and patients with CD followed a regimen confined to enteral feeds alone for 1 or 2 weeks, respectively. Chemicals excreted on breath or in faeces were characterised at the start and at the end of the feeding period by gas chromatography/mass spectrometry. RESULTS: One week of feeding in healthy volunteers caused significant changes in stool colour and deterioration in breath odour, together with increased excretion of phenol and indoles on the breath. Feeding for 2 weeks in patients with CD produced significant improvements in symptoms and a decrease in the concentration of C-reactive protein. The faecal concentrations of microbial products, including short-chain fatty acids (SCFAs), and potentially toxic substances, including 1-propanol, 1-butanol and the methyl and ethyl esters of SCFAs, showed significant falls. CONCLUSIONS: A significant change occurs in the production of microbial metabolites after enteral feeding in both healthy volunteers and patients with CD. Many of those detected in CD are toxic and may feasibly lead to the immunological attack on the gut microbiota, which is characteristic of inflammatory bowel disease. The reduction in the production of such metabolites after enteral feeding may be the reason for its effectiveness in CD.

Characterisation of the faecal metabolome and microbiome of Thoroughbred racehorses.

REASONS FOR PERFORMING STUDY: The intestinal bacterial community of the horse is a key determinant of intestinal and whole body health. Understanding the bacterial community structure and function is an important foundation for studies of intestinal health and disease. OBJECTIVES: To describe the faecal bacterial community and volatile organic compounds (VOCs) of the faecal metabolome of healthy Thoroughbred racehorses and to characterise responses to dietary supplementation with amylase-rich malt extract. STUDY DESIGN: Intervention study. METHODS: Faecal samples were collected noninvasively before and 6 weeks after supplementation in 8 privately owned Thoroughbred racehorses in active race training. Faecal metabolome was characterised using thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS), with spectral analysis performed using AMDIS and compared against the NIST database. Taxonomic description of the faecal microbiota was achieved using error-corrected 454 pyrosequencing data from 16S rRNA gene amplicons. RESULTS: The faecal metabolome of our study population was dominated by organic acids, alcohols and ketones. We identified 81 different VOCs only 28 of which were present in >50% of samples indicating functional diversity. Faecal VOC profiles differed between first and second sampling point, some VOCs being significantly reduced post supplementation, consistent with a marked response to dietary amylase-rich malt extract. Faecal microbiota was characterised as highly diverse; samples demonstrated verifiable diversity in the range 1200-3000 operational taxonomic units (OTUs) per individual. The methods used also describe high levels of infrequent, low abundance OTUs. Faecal microbial community structure was found to be different following dietary supplementation. Differences in several low abundance bacterial taxa were detected and also some evidence of interhorse variation in response. CONCLUSIONS: The volatile faecal metabolome of Thoroughbred racehorses is dominated by organic acids, alcohols and ketones; this study demonstrates that dietary supplementation with amylase-rich malt extract may significantly alter the profile of VOCs. The faecal microbiome is highly diverse, dominated by Firmicutes and Bacteroidetes. Small but significant changes in microbial community structure were detected following dietary supplementation. This study describes the faecal metabolome and microbiome of healthy Thoroughbred racehorses against which future studies of disease and dietary intervention can be benchmarked.

Nitric oxide affects mammalian distal colonic smooth muscle by tonic neural inhibition.

1 The role of the L-arginine-nitric oxide (NO) pathway in tonic neural inhibition of spontaneous mechanical activity of distal colonic circular smooth muscle (DCCSM) was investigated in male Wistar rats. 2 Muscle strips were mounted in organ baths and spontaneous contractions recorded with isometric force transducers. They were characterized as low frequency (LFCs) 0.41 +/- 0.03 N cm-2 or high frequency contractions (HFCs) 0.22 +/- 0.04 N cm-2. The latter occurred intermittently to produce summation contractions (SCs) range 0.5-12 N cm-2. 3 Tetrodotoxin (100 nM) increased the forces of LFCs and SCs. Increase in force to tetrodotoxin did not occur after incubation of the muscle with NG-monomethyl-L-arginine (L-NMMA) 500 microM, an inhibitor of NO biosynthesis. 4 L-NMMA but not its enantiomer D-NMMA increased the force of LFCs (EC50: 200 microM) and SCS (EC50:175 microM) in a concentration-dependent manner which was reversed by L-arginine but not by D-arginine. 5 Muscle, precontracted by acetylcholine, relaxed to sodium nitroprusside (EC50:1.8 microM) NO gas (EV50:70 microliters) and NO solutions (EC50:4 microM) in a concentration-dependent manner. Guanosine 3':5'-cyclic monophosphate tissue concentrations (pmol mg-1 protein) were elevated in muscle after relaxation by sodium nitroprusside (500 microM) from 0.32 +/- 0.06 to 1.2 +/- 0.37 and by 1 ml of NO gas from 0.49 +/- 0.05 to 1.54 +/- 0.14. 6 These data suggest that DCCSM is under tonic neural inhibition mediated by NO biosynthesis.

The effect of a non-absorbable fat substitute, sucrose polyester, on gastrointestinal function.

OBJECTIVES: To assess the effects of a single dose of a non-absorbable fat substitute, sucrose polyester, on gastrointestinal function. METHODS: The effects of 50 g of sucrose polyester taken as a single drink on gastric emptying, small bowel transit time (SBTT), whole gut transit time (WGTT) and faecal weight compared with a control fat were examined in double-blind studies. The effect of sucrose polyester on gallbladder ejection fraction and gastrointestinal hormones was also assessed. RESULTS: Sucrose polyester was found to accelerate gastric emptying significantly (98.33 +/- 71.0 vs. 112.92 +/- 82.0 min, P = 0.042) but to slow SBTT (153.75 +/- 36.25 vs. 128.75 +/- 47.39 min. P = 0.006). A trend to faster WGTT (37.47 +/- 15.61 vs. 46.63 +/- 20.65 h) and increased faecal weight was observed (453.33 +/- 122.05 vs. 395.0 +/- 107.85 g/48 h), but this did not reach statistical significance. There was a striking reduction in gallbladder ejection fraction with sucrose polyester (21.69 +/- 25.32 vs. 45.27 +/- 27.67%), P = 0.039) and a corresponding significant decrease in the release of cholecystokinin. Lower levels of motilin and enteroglucagon were also observed. CONCLUSIONS: Sucrose polyester has significant effects on gastrointestinal transit, gallbladder contraction and gastrointestinal hormones. These effects can be explained on the basis of decreased luminal products of digestion and may have implications for the widespread use of sucrose polyester as a fat substitute.

Idiopathic slow-transit constipation: whole gut transit times, measured by a new simplified method, are not shortened by opioid antagonists.

A simplified method for measuring mean whole gut transit time has been validated which avoids stool collection and is suitable for out-patients. Radio-opaque markers are swallowed daily for 14 days and the mean whole gut transit time is derived directly from an abdominal X-ray. Using this new technique, neither nalmefene (in a double-blind study of six patients) nor naloxone (in an open study of four patients) shortened mean whole gut transit time in idiopathic slow-transit constipation.

A double-blind, randomized, placebo-controlled trial of essential fatty acid supplementation in the maintenance of remission of ulcerative colitis.

BACKGROUND: Essential fatty acid supplementation has been found to ameliorate certain chronic inflammatory diseases. This effect is thought to be mediated through the modulation of eicosanoid synthesis. Pro-inflammatory eicosanoids have been implicated in ulcerative colitis. AIM: To investigate the possible therapeutic benefit of essential fatty acids in quiescent ulcerative colitis to reduce the frequency of disease relapse. METHODS: A randomized, double-blind, placebo-controlled study was performed with a treatment duration of 12 months. Patients with quiescent disease received either trial medication (gamma-linolenic acid, 1.6 g, eicosapentaenoic acid, 270 mg, and docosahexaenoic acid, 45 mg, per day) or placebo (sunflower oil, 500 mg/day). The primary end-point was disease activity, assessed by a previously validated clinical index, sigmoidoscopic appearance and histology. RESULTS: Sixty-three patients were randomized, 31 to receive essential fatty acid treatment and 32 to receive placebo. Disease relapse rates were similar at 12 months (placebo, 38%; essential fatty acids, 55%), as were changes in sigmoidoscopic grade from baseline. CONCLUSIONS: The supplementation of the diet with this combination of essential fatty acids does not prolong the period of disease remission of ulcerative colitis.

Review article: the dietary management of Crohn's disease.

Enteral feeding has been shown to be as effective as primary therapy for Crohn's disease, but it requires high patient motivation, may be unpalatable and is expensive. However, in adolescents with growth failure and when corticosteroid therapy is contra-indicated or has failed, it may become the treatment of choice. Furthermore, dietary therapy allows circumvention of the adverse side-effects of repeated courses of steroids. A number of different hypotheses have been proposed to explain the effect of enteral feeds but none has reached universal acceptance. Prospective trials suggest that the exclusion of whole protein is not necessary. Comparison of feeds with differing composition suggests that a low fat content increases efficacy and various explanations have been offered. The reduction of colonic bacterial load may also be important. Because symptoms of Crohn's disease may be provoked by eating, there is a risk of falsely attributing symptoms to specific foodstuffs. However, in many individuals foods can be identified which affect disease activity, and their exclusion leads to prolongation of disease remission. Dietetic supervision during food testing is important to avoid detrimental effects on nutrient and micronutrient intake.

Xanthine oxidase activity is not increased in the colonic mucosa of ulcerative colitis.

AIM: To measure urate and xanthine by high-performance liquid chromatography in mucosal biopsies from patients with ulcerative colitis and controls. RESULTS: Reactive oxygen metabolite activity was demonstrated by a cystine to cysteine ratio of 0.24 +/- 0.08 in the control biopsies compared with 1.79 +/- 0.25 in ulcerative colitis. The product to substrate ratio (urate to xanthine) for xanthine oxidase and mucosal urate concentrations were not different between ulcerative colitis patients and controls. Xanthine oxidase activity after incubation of homogenized biopsies was 0.451 (+/- 0.175) nmol.min/mg protein in ulcerative colitis patients compared with 2.585 (+/- 0.823) nmol.min/mg protein in controls (P < 0.01). CONCLUSION: These results suggest that xanthine oxidase may not be the major source of superoxide formation in ulcerative colitis.

The effects of aminosalicylic acid derivatives on nitric oxide in a cell-free system.

AIMS AND METHODS: To determine the effect of aminosalicylic acid derivatives on the concentration of nitric oxide produced in a cell-free system, by the use of a sensitive and specific polarographic meter. RESULTS: The aminosalicylic acid derivatives 3-ASA (IC50 100 microM), 4-ASA (IC50 350 microM) and 5-ASA (IC50 5 microM) all decreased the nitric oxide signal. These drugs had a similar inhibitory effect on the formation in vitro of nitrite from sodium nitroprusside (IC50: 200 microM, 500 microM and 100 microM, respectively). Sulphasalazine (31.1 +/- 5% decrease in signal at 1 mM) was less effective than 5-ASA, but sulphapyridine, N-acetyl 5-ASA, indomethacin and hydrocortisone produced no decrease in nitric oxide signal at all. CONCLUSIONS: Nitric oxide binding may be part of the mechanism by which ASA derivatives exert their therapeutic effect, and this work suggests that it may be an important factor in the pathogenesis of ulcerative colitis.

The physiological expression of inducible nitric oxide synthase (iNOS) in the human colon.

BACKGROUND: Inducible nitric oxide synthase (iNOS) is expressed in the colonic epithelium in both inflammatory bowel disease and colorectal cancer. Nitric oxide (NO), the product of this enzyme, has been implicated in the pathogenesis of both conditions. However, there are conflicting data on whether iNOS is expressed in the normal, uninflamed human colon. AIMS: To evaluate the expression of iNOS in histologically normal, non-inflamed human colonic mucosa. PATIENTS/METHODS: Reverse transcription polymerase chain reaction (RT-PCR), immunoblotting, and immunohistochemistry were used to investigate the expression of iNOS in 17 histologically normal specimens obtained at colectomy performed for colorectal neoplasia. In addition, 16 endoscopic mucosal biopsies, taken from normal individuals, were also evaluated. Eleven surgical specimens and 16 endoscopic biopsies from patients with refractory ulcerative colitis were used as inflammatory controls. RESULTS: All types of specimens expressed iNOS mRNA. Immunoblotting revealed a protein of approximately 130 kDa consistent with iNOS in mucosal extracts of 77% of normal individuals, and 85% of diseased controls. Immunolabelling localised this protein to the surface epithelium in most of the normal specimens and also to the crypt epithelium and inflammatory cells in the diseased controls. CONCLUSIONS: These findings provide evidence that iNOS is often expressed in the surface epithelium of non-inflamed human colon, suggesting that it is induced by local luminal factors, such as bacterial lipopolysaccharide (endotoxin). The resultant NO produced at this site might act as an oxidative barrier, reducing bacterial translocation and providing a means of defence against pathogenic microorganisms.

Accuracy of serology for the diagnosis of Helicobacter pylori infection--a comparison of eight kits.

AIMS: To determine the accuracy of eight commercially available kits for the serological diagnosis of Helicobacter pylori infection, and hence whether a serology service could be introduced to reduce endoscopy workload. METHODS: Eighty four patients newly presenting to their general practitioners with dyspepsia were recruited. Gold standard diagnosis of H pylori infection was obtained both by a histological examination of gastroduodenal biopsy specimens and by the 14C-urea breath test (UBT). The performance of six quantitative and two qualitative enzyme linked immunosorbent assays for H pylori IgG, used according to the manufacturers' instructions, with serum samples obtained during the endoscopy visit, were compared. RESULTS: The study population had a median age of 45 years, and the prevalence of H pylori infection was 35%. With one exception, where the patient had received a course of anti-H pylori treatment between endoscopy and UBT, there was 100% concordance in the results of the two gold standard techniques. Discordant serology results were more common in patients aged > 50 years (42% of the total) than in younger patients (21%), and this was most noticeable in uninfected patients. The sensitivity of the kits was good (90-100%), but specificity was more variable (76-96%), and the rate of equivocal results was unacceptably high in some cases (0-12%). The overall accuracy of the kits ranged from 83 to 98%. Two kits in particular performed well (Pylori-Elisa II, Bio-Whitaker and Premier, Launch; qualitative) with 98% and 100% accuracy, respectively. CONCLUSIONS: In a symptomatic population with a prevalence of H pylori infection of 35%, particularly in patients aged < 50 years, some but not all serology kits may be used as a highly accurate and inexpensive alternative to the gold standard techniques.

Instability in the faecal flora of a patient suffering from food-related irritable bowel syndrome.

The faecal microbial flora of a patient with severe irritable bowel syndrome related to multiple food intolerances was very variable and contained a high proportion of facultative bacteria and an unusual incidence of Clostridium species.

The faecal flora of two patients with food-related irritable bowel syndrome during challenge with symptom-provoking foods.

The faecal microbial flora of two patients with food-related irritable bowel syndrome was examined while they were on a diet excluding symptom-provoking foods, and then on a diet including such a food. The patients reacted differently to the challenge diet but some changes in faecal output, flora and short chain fatty acid content were seen.

Treatments for Crohn's disease that minimise steroid doses are associated with a reduced risk of osteoporosis.

Crohn's disease is associated with an increased prevalence of osteoporosis. Corticosteroids, commonly used to control exacerbations, appear to be a major risk factor for subsequent development of osteoporosis. Exclusion diets, avoiding foods that precipitate symptoms, frequently allow control of the disease avoiding the use of corticosteroids and may thereby reduce the risk of osteoporosis. To investigate this we performed bone mineral density measurements of the proximal femur and spine in 95 patients, 31 treated predominately by corticosteroids, 33 by dietary manipulation with a low life-time corticosteroid dose and 31 by treatments other than diets but also with a low life-time corticosteroid dose. In both groups with a low life-time corticosteroid dose bone mineral density was comparable to that of age-matched normal controls, whereas bone mineral density was significantly reduced in those treated predominately by corticosteroids. We conclude that corticosteroid therapy is an independent risk factor for osteoporosis in patients with Crohn's disease and should be used as little as possible.

Long-chain triglycerides reduce the efficacy of enteral feeds in patients with active Crohn's disease.

Elemental diets are effective treatments for active Crohn's disease. To determine which dietary constituents are of therapeutic importance, the effectiveness of four separate feeds was related to their compositions, and the findings substantiated by meta-analysis of previous dietary studies. 76 patients with active Crohn's disease were recruited. 17 were randomised to an amino acid-based elemental diet (E028), 22 to E028 with added long-chain triglyceride (E028 LCT), 18 to a semi-elemental, peptide based diet (Pepdite 2+) and 19 received E028 with added medium-chain triglyceride (E028 MCT). Disease activity fell in all groups and remission rate was negatively correlated with the amount of energy derived from LCT (r = -0.97, p = 0.016). Inflammatory indices fell in the groups (E028 + E028 MCT) containing least LCT. No other dietary constituents correlated with remission rate. A meta-analysis of published studies confirmed a negative correlation between remission rate and LCT (r = -0.63, p = 0.006) but not other constituents. The association between dietary LCT and remission rate may have pathogenic significance and allow the development of more effective enteral feeds.

An open-label phase I/II dose escalation study of the treatment of pancreatic cancer using lithium gammalinolenate.

There are currently no satisfactory treatments for inoperable pancreatic cancer. Median survivals for untreated patients are of the order of 100 days and, with one exception, no chemotherapy or radiotherapy regime has been found to produce a worthwhile extension of life with reasonably tolerable side effects. Gamma-linolenic acid (GLA) has been found to kill about 40 different human cancer cell lines in vitro without harming normal cells. The lithium salt of GLA (LiGLA) can be administered intravenously and a dose escalation study of a 10 day infusion followed by oral therapy in patients with inoperable pancreatic cancer was carried out in 48 patients in two centres. Peripheral venous infusion caused thrombophlebitis but this could be avoided by infusing via a central vein with appropriate heparinisation. Too rapid infusion caused haemolysis which could be avoided by slow dose escalation in the first few days and maintenance of plasma lithium below 0.8 mmol/l. Doses ranged from 7 to 77g/patient cumulatively delivered over 2-12 days. Other than the above described events there were no important side effects and patients felt well during the infusions. A Kaplan-Meier analysis showed that survival was not significantly influenced by which centre the patients were treated in, the sex of the patients or the presence or absence of histological confirmation. The presence or absence of liver metastases, the patients' Karnofsky scores and the-dose of LiGLA had significant effects on survival from treatment. A Cox proportional hazards model revealed similar results: in both centres, in both sexes, and in patients with and without liver metastases according to the model the highest doses of LiGLA were associated with longer survival times as compared with the lowest doses. LiGLA deserves investigation in a randomised prospective study.

Nutritional factors in inflammatory bowel disease.

During the past 20 years there has been growing interest in the importance of nutritional factors in the pathogenesis of inflammatory bowel disease. There are so far no definite links between ulcerative colitis and diet, but links with Crohn's disease have been studied by both epidemiologists and clinicians. Epidemiological studies, although retrospective, have suggested that patients with Crohn's disease eat more sugar and sweets that control individuals; however, when dietary sugar is restricted, there is little clinical benefit. The clinical approach to nutrition in Crohn's disease has been by the use of elemental diets, which will produce symptomatic and objective remission in up to 90% of compliant patients. Those who return to normal eating soon relapse but, in some studies, have enjoyed prolonged remission on exclusion diets. The foods excluded have been not sugar, but predominantly cereals, dairy products and yeast. Attention has now switched to the possible harmful role of fat in Crohn's disease. The efficacy of elemental feeds appears to depend not on the presentation of nitrogen but on the amount of long chain triglyceride present. Increases in recent years in the frequency of Crohn's disease in Japan have been correlated with increased dietary fat intake, and a recent study suggested that W-3 fatty acids, which are metabolized by immunomodulatory leukotrienes and prostaglandins, may have a beneficial role to play. The links between nutrition and Crohn's disease have now become strong and the role of fat may be the most exciting of all.

Evaluation of the effectiveness of a specialist nurse in the management of inflammatory bowel disease (IBD).

OBJECTIVE: To determine the effect of a specialist nurse on the management outcome of patients with inflammatory bowel disease (IBD). DESIGN: Audit of the management of a cohort of patients in the year prior to the employment of the specialist nurse and the year immediately after. SUBJECTS: 339 patients, both male and female, with either Crohn's disease or ulcerative colitis, resident in the Cambridge health district. SETTING: Addenbrooke's Hospital NHS Trust Outpatient Centre. MAIN OUTCOME MEASURE: Health status was measured by blood tests (C-reactive protein, albumin and haemoglobin) throughout the year, symptom indices, number of clinic attendances, admissions to hospital and length of stay. Quality of life was measured via a postal questionnaire. RESULTS: Hospital visits were reduced from 1377 to 853 (38% reduction) and in-patient length of stay measured in bed-days from 516 to 417 (19% reduction). The number of patients in remission increased from 63 to 69%. Patient satisfaction improved in key areas, in particular, access to information on IBD and advice on avoidance of illness and maintaining health. Of a total of 251 calls to the telephone helpline, only 19 patients were referred for a medical opinion and five patients required hospital admission. CONCLUSION: The IBD nurse specialist is a valuable and cost-effective member of the gastroenterology team.