Mid Colon Research Articles

Microstructure-based constitutive modeling for the large intestine validated by histological observations

Other than its transport role, the large bowel performs numerous sophisticated functions, e.g. water, electrolyte, and vitamin absorption, optimized by its contractile properties and passive recoil capacity, but these properties have attracted limited attention than has been the case for other parts of the gastrointestinal tract. Accordingly, we investigated in vitro the pseudo-elastic properties of tubular specimens from the ascending, mid, and descending colon, and the rectum of healthy Wistar rats under passive quasi-static conditions and a physiologic range of pressures/axial stretches. A neo-Hookean and five-fiber family model was chosen as a microstructure-based material model for its efficiency in producing accurate representations of the three-dimensional inflation/extension data in relation to the underlying microstructure. Guided by our optical microscopy observations, this model took account of isotropic elastin properties and multi-directional collagen organization, but suffered from parameter covariance. Moreover, the contributions to the total model of the neo-Hookean and circumferential-fiber family were negligible, given the tiny amounts of elastin and circumferentially-arranged collagen fibers that were disclosed histologically, and the contributions of the diagonal and radial-fiber families to data representation were similar. The multiaxial response of the intestinal wall was fit equally accurately but without over-parameterization problems by the neo-Hookean and three-fiber (diagonal and axial) family model. The preferred alignment of collagen fibers towards the axial direction bestowed increased axial stiffness to the tissue. The mid colon was the stiffest region by virtue of its greatest material parameters, as validated by its higher collagen content than that of the distal regions. The present findings generate a more cohesive understanding of the large bowel in histomechanical terms, with potential for clinical and biomedical applications.

Stool substitute transplant therapy for the eradication of Clostridium difficile infection: ‘RePOOPulating’ the gut

BackgroundFecal bacteriotherapy (‘stool transplant’) can be effective in treating recurrent Clostridium difficile infection, but concerns of donor infection transmission and patient acceptance limit its use. Here we describe the use of a stool substitute preparation, made from purified intestinal bacterial cultures derived from a single healthy donor, to treat recurrent C. difficile infection that had failed repeated standard antibiotics. Thirty-three isolates were recovered from a healthy donor stool sample. Two patients who had failed at least three courses of metronidazole or vancomycin underwent colonoscopy and the mixture was infused throughout the right and mid colon. Pre-treatment and post-treatment stool samples were analyzed by 16 S rRNA gene sequencing using the Ion Torrent platform.ResultsBoth patients were infected with the hyper virulent C. difficile strain, ribotype 078. Following stool substitute treatment, each patient reverted to their normal bowel pattern within 2 to 3 days and remained symptom-free at 6 months. The analysis demonstrated that rRNA sequences found in the stool substitute were rare in the pre-treatment stool samples but constituted over 25% of the sequences up to 6 months after treatment.ConclusionThis proof-of-principle study demonstrates that a stool substitute mixture comprising a multi-species community of bacteria is capable of curing antibiotic-resistant C. difficile colitis. This benefit correlates with major changes in stool microbial profile and these changes reflect isolates from the synthetic mixture.Trial registrationClinical trial registration number: CinicalTrials.gov NCT01372943

Improving Quality of Colonoscopy Bowel Preparation with an Educational Video: Presidential Poster

Purpose: To evaluate the impact of a supplementary bowel preparation instructional video on the quality of colonoscopy preparation and patient satisfaction Methods: 127 patients scheduled for an outpatient colonoscopy were prospectively randomized in a single blinded manner to video or non-video group. In addition to written bowel preparation instructions, patients in the video group viewed a brief instructional video prior to starting their preparation. All patients prepped with SUPREP Bowel Prep Kit and had a morning colonoscopy. Quality of colon preparation was measured by the endoscopist using the Ottawa Bowel Preparation Quality Scale, a validated instrument requiring the endoscopist to rate cleansing in three segments (right colon, mid colon, and recto-sigmoid colon) on a scale of 0 - 4, with 0 indicating perfect cleansing, and overall fluid quantity on a scale of 0 - 2, with 0 indicating no fluid in the colon. The individual scores are summed to create a total score, with lower scores indicating better preparation. Patient satisfaction with preparation was evaluated using a questionnaire. Statistical analysis was employed to evaluate the impact of the colonoscopy video. Results: There were significant differences in the quality of colonoscopy preparation between the video and the non-video group. Participants that watched the video had superior preparation scores in the right colon (0.71 vs 1.47, p<0.001), transverse colon (0.73 vs 1.44, p<0.001), left colon (0.77 vs 1.45, p<0.001), fluid content (0.87 vs 1.22, p=0.004), and aggregate score (3.08 vs 5.58, p<0.001). Video had no impact on patient satisfaction, with about 85% of patients in both groups rating their satisfaction as a 4 or 5 (5 point scale with 5 = satisfied). The higher the patient's level of education, the lower the Ottawa score of the left colon with a correlation of -.20 (p<.05). Age was significantly related to left colon preparation with a correlation of .19 (p<.05) such that older individuals had less effective cleaning in this segment. Although older patients were more likely to find their previous colonoscopy experiences to be more satisfying (significant correlation of .44 (p<.05)), only 21% of all patients who had a prior colonoscopy found the previous experience more satisfying. Socioeconomic status, ethnicity, gender, or family history of colon cancer did not reveal any significant correlation to quality of colonoscopy preparation or patient satisfaction. Conclusion: Adequate bowel cleansing remains an important factor for providing a quality study of the colon. The addition of an instructional bowel preparation video significantly improves the quality of colon preparation. Disclosure: Sateesh R. Prakash, M.D.- research grant from Braintree Laboratories, Inc for the submitted research abstract and study. This research was supported by an industry grant from Braintree Laboratories, Inc.

Neurogenic and myogenic motor patterns of rabbit proximal, mid, and distal colon

The rabbit colon consists of four distinct regions. The motility of each region is controlled by myogenic and neurogenic mechanisms. Associating these mechanisms with specific motor patterns throughout all regions of the colon has not previously been achieved. Three sections of the colon (the proximal, mid, and distal colon) were removed from euthanized rabbits. The proximal colon consists of a triply teniated region and a single tenia region. Spatio-temporal maps were constructed from video recordings of colonic wall diameter, with associated intraluminal pressure recorded from the aboral end. Hexamethonium (100 μM) and tetrodotoxin (TTX; 0.6 μM) were used to inhibit neural activity. Four distinct patterns of motility were detected: 1 myogenic and 3 neurogenic. The myogenic activity consisted of circular muscle (CM) contractions (ripples) that occurred throughout the colon and propagated in both antegrade (anal) and retrograde (oral) directions. The neural activity of the proximal colon consisted of slowly (0.1 mm/s) propagating colonic migrating motor complexes, which were abolished by hexamethonium. These complexes were observed in the region of the proximal colon with a single band of tenia. In the distal colon, tetrodotoxin-sensitive, thus neurally mediated, but hexamethonium-resistant, peristaltic (anal) and antiperistaltic (oral) contractions were identified. The distinct patterns of neurogenic and myogenic motor activity recorded from isolated rabbit colon are specific to each anatomically distinct region. The regional specificity motor pattern is likely to facilitate orderly transit of colonic content from semi-liquid to solid composition of feces.

Up-regulated cystic fibrosis transmembrane conductance regulator after anal stenosis in rats

BackgroundThe pathophysiology of fecal incontinence from fecal impaction and rectal distension is poorly understood. We hypothesize that fecal impaction elicits up-regulation of cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated mucosal chloride channel. MethodsThe anus was ligated to produce 75% stenosis in rats. Controls received ligation without inducing stenosis. 24 to 48 hours after ligation the colon was removed. Mucosal short-circuit current was measured by Ussing chamber. Western blot analysis was used to detect CFTR expression in the colonic mucosa. Ligated rats failed to defecate, whereas control rats stooled normally. ResultsLigated colons were markedly stool filled and dilated. Water content of feces was significantly increased to 66.5% ± 1.1% (P < .01, n = 12) 24 hours after ligation, vs controls (49.5 ± 5.2%, n = 12). Baseline short-circuit current was significantly increased in the distal (78.8 ± 7.4 μA/cm2, n = 8, P < .01) and mid colon (24.5 ± 2.5 μA/cm2, n = 8, P < .05) 24 hours after ligation, compared to control rats (12.5 ± 3.2 μA/cm2, n = 8). CFTR expression was significantly increased 24 hours after ligation in the mid and distal colon. ConclusionWe observe that fecal impaction from anal ligation induces early compensatory up-regulation of CFTR, altering function from net absorption to net secretion in the mid and distal colon.

Optimal preparation-to-colonoscopy interval in split-dose PEG bowel preparation determines satisfactory bowel preparation quality: an observational prospective study

Several factors influence bowel preparation quality. Recent studies have indicated that the time interval between bowel preparation and the start of colonoscopy is also important in determining bowel preparation quality. To evaluate the influence of the preparation-to-colonoscopy (PC) interval (the interval of time between the last polyethylene glycol dose ingestion and the start of the colonoscopy) on bowel preparation quality in the split-dose method for colonoscopy. Prospective observational study. University medical center. A total of 366 consecutive outpatients undergoing colonoscopy. Split-dose bowel preparation and colonoscopy. The quality of bowel preparation was assessed by using the Ottawa Bowel Preparation Scale according to the PC interval, and other factors that might influence bowel preparation quality were analyzed. Colonoscopies with a PC interval of 3 to 5 hours had the best bowel preparation quality score in the whole, right, mid, and rectosigmoid colon according to the Ottawa Bowel Preparation Scale. In multivariate analysis, the PC interval (odds ratio [OR] 1.85; 95% CI, 1.18-2.86), the amount of PEG ingested (OR 4.34; 95% CI, 1.08-16.66), and compliance with diet instructions (OR 2.22l 95% CI, 1.33-3.70) were significant contributors to satisfactory bowel preparation. Nonrandomized controlled, single-center trial. The optimal time interval between the last dose of the agent and the start of colonoscopy is one of the important factors to determine satisfactory bowel preparation quality in split-dose polyethylene glycol bowel preparation.

Phentermine Induced Ischemic Colitis

Purpose: Introduction: Weight loss medications have historically been cautiously supported due to adverse side effects such as pulmonary hypertension and valvular heart disease. In 1997 the FDA withdrew the combination of fenfluramine and dexfenfluramine from the market due to these adverse events. Phentermine, a commonly prescribed medication for short-term weight loss, works as a sympathomimetic and is an amphetamine derivative that remains available for prescription. We report a unique case of severe ischemic colitis following the use of phentermine in a patient with no other risk factors for ischemia. Case Presentation: A 57 year old female GI nurse presented to the emergency room complaining of bilateral lower quadrant abdominal pain followed by hematochezia two hours later. Digital rectal exam in the ER revealed bright red blood. Past medical history was unremarkable for any risk factors for gastrointestinal ischemia aside from well-controlled hypertension on a single antihypertensive. Phentermine had been prescribed five months prior at a dose of 30mg daily for weight loss. A colonoscopy was performed and showed diffuse contiguous erythema, superficial ulceration, and edema from the mid sigmoid colon to the mid transverse colon. A strictured area was also appreciated in the descending colon. The rectal and proximal colonic mucosa were normal. Biopsies obtained showed patchy mucosal hemorrhage and necrosis and confirmed the diagnosis of ischemic colitis. Phentermine had been held on admission and all symptoms resolved within 48 hours with supportive care. Two months later the patient remains asymptomatic and has not resumed her weight loss supplement. Discussion: There is one case report of ischemic colitis following fenfluramine in combination with dexfenfluramine. There is, however, only one published case report of phentermine in association with ischemic colitis that only involved a small segment at the splenic flexure. Gastrointestinal bleeding is not listed as a possible side effect of this commonly prescribed medication. Phentermine has been associated with ischemic neurologic events such as transient ischemic attacks and cerebral infarcts and could, through similar physiology, cause gastrointestinal ischemia. This unique case describes an instance of severe ischemic colitis following the use of phentermine involving almost the entire left colon and highlights the need for heightened awareness to identify patients and inform providers of the risk of gastrointestinal ischemia from this medication.

Pretreatment with the probiotic VSL#3 delays transition from inflammation to dysplasia in a rat model of colitis-associated cancer

Evidence supports involvement of microflora in the transition of chronic inflammation to neoplasia. We investigated the protective efficacy of the probiotic VSL#3 in a model of colitis-associated colorectal cancer. Chronic colitis was induced in Sprague-Dawley rats by administration of trinitrobenzene sulfonic acid (TNBS), followed 6 wk later by systemic reactivation. To induce colitis-associated dysplasia and cancer, the animals received TNBS (intravenously) twice a week for 10 wk. One group received VSL#3 in drinking water from 1 wk before colitis induction until death. The colons were examined for damage and presence of dysplasia or cancer. Samples were analyzed for cell proliferation and apoptosis, vitamin D receptor (VDR) expression, angiogenic factors, and presence of alkaline sphingomyelinase or phosphatase. Microbial community composition was evaluated by terminal restriction fragment-length polymorphism analysis of the bacterial 16S rRNA gene. None of the probiotic-treated animals developed carcinoma, and no high-grade dysplasia was found in either the proximal or mid colon. In contrast, 29% of the animals in the control group developed carcinoma in one or more regions of the colon. VSL#3-treated animals had significantly less damage than the vehicle treated-controls in all areas of the colon, and this correlated with decreased richness and diversity of the mucosally adherent microbiota. Treatment with the probiotic increased the antiangiogenic factor angiostatin, VDR expression, and alkaline sphingomyelinase. We concluded that pretreatment with the probiotic VSL#3 can attenuate various inflammatory-associated parameters, delaying transition to dysplasia and cancer, thus offering its potential therapeutic use in patients with long-standing colitis.

Diversity of the Formyltetrahydrofolate Synthetase (FTHFS) Gene in the Proximal and Mid Ostrich Colon

We analysed fragments of the formyltetrahydrofolate synthetase (FTHFS) gene, which encodes a key enzyme in reductive acetogenesis, from the bacterial flora in the proximal (PC) and mid (MC) colon of three ostriches to assess and compare bacterial diversity in this organ. Two clone libraries of FTHFS fragments were constructed from DNA extracted from digesta of the PC and MC, and a total of 46 cloned sequences were analysed from each library. A wide variety of FTHFS sequences were recovered. The coverage of the PC and MC libraries was 90.0% and 83.3%, respectively. Shannon-Wiener index (H') and Chao1 of the MC library were higher than those of PC library. The sequences from each library were classified into 15 operational taxonomic units (OTUs) and clusters. Only four OTUs in cluster I were distantly related to known acetogens from human feces and rumen, suggesting the presence of the novel acetogens. Phylogenetic analysis suggests that composition of FTHFS sequences differs for the PC and MC.

Effects of autonomic nerve stimulation on colorectal motility in rats

Several disease processes of the colon and rectum, including constipation and incontinence, have been associated with abnormalities of the autonomic nervous system. However, the autonomic innervation to the colon and rectum are not fully understood. The aims of this study were to investigate the effect of stimulation of vagus nerves, pelvic nerves (PN) and hypogastric nerves (HGN) on colorectal motility in rats. Four strain gauge transducers were implanted on the proximal colon, mid colon, distal colon and rectum to record circular muscle contractions in rats. Electrical stimulation was administered to the efferent distal ends of the cervical vagus nerve, PN and HGN. Motility index (MI) was evaluated before and during stimulation. Electrical stimulation (5-20 Hz) of the cervical vagus elicited significant contractions in the mid colon and distal colon, whereas less pronounced contractions were observed in the proximal colon. Pelvic nerves stimulation elicited significant contractions in the rectum as well as the mid colon and distal colon. Atropine treatment almost completely abolished the contractions induced by vagus nerve and PN stimulation. Hypogastric nerves stimulation caused relaxations in the rectum, mid colon and distal colon. The relaxations in response to HGN stimulation were abolished by propranolol. Vagal innervation extends to the distal colon, while the PN has projections in the distribution of the rectum through the mid colon. This suggests a pattern of dual parasympathetic innervation in the left colon. Parasympathetic fibers regulate colorectal contractions via muscarinic receptors. The HGN mainly regulates colorectal relaxations via beta-adrenoceptors.

Mucin Dynamics in Intestinal Bacterial Infection

BackgroundBacterial gastroenteritis causes morbidity and mortality in humans worldwide. Murine Citrobacter rodentium infection is a model for gastroenteritis caused by the human pathogens enteropathogenic Escherichia coli and enterohaemorrhagic E. coli. Mucin glycoproteins are the main component of the first barrier that bacteria encounter in the intestinal tract.Methodology/Principal FindingsUsing Immunohistochemistry, we investigated intestinal expression of mucins (Alcian blue/PAS, Muc1, Muc2, Muc4, Muc5AC, Muc13 and Muc3/17) in healthy and C. rodentium infected mice. The majority of the C. rodentium infected mice developed systemic infection and colitis in the mid and distal colon by day 12. C. rodentium bound to the major secreted mucin, Muc2, in vitro, and high numbers of bacteria were found in secreted MUC2 in infected animals in vivo, indicating that mucins may limit bacterial access to the epithelial surface. In the small intestine, caecum and proximal colon, the mucin expression was similar in infected and non-infected animals. In the distal colonic epithelium, all secreted and cell surface mucins decreased with the exception of the Muc1 cell surface mucin which increased after infection (p<0.05). Similarly, during human infection Salmonella St Paul, Campylobacter jejuni and Clostridium difficile induced MUC1 in the colon.ConclusionMajor changes in both the cell-surface and secreted mucins occur in response to intestinal infection.

Increased induction of apoptosis by Propionibacterium freudenreichii TL133 in colonic mucosal crypts of human microbiota-associated rats treated with 1,2-dimethylhydrazine

Propionibacterium freudenreichii, a food-grade bacterium able to kill colon cancer cell lines in vitro by apoptosis, may exert an anticarcinogenic effect in vivo. To assess this hypothesis, we administered daily 2 x 10(10) colony-forming units (CFU) of P. freudenreichii TL133 to human microbiota-associated (HMA) rats for 18 d. Either saline or 1,2-dimethylhydrazine (DMH) was also administered on days 13 and 17 and rats were killed on day 19. The levels of apoptosis and proliferation in the mid and distal colon were assessed by terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) and proliferating cell nuclear antigen (PCNA) immunolabelling, respectively. The administration of P. freudenreichii TL133 significantly increased the number of apoptotic cells in DMH-treated rats compared to those given DMH only (P < 0.01). Furthermore, propionibacteria were able to decrease the proliferation index in the distal colon after treatment with DMH (P < 0.01). Conversely, propionibacteria alone did not exert such an effect on healthy colonic mucosa. P. freudenreichii TL133 thus facilitated the elimination of damaged cells by apoptosis in the rat colon after genotoxic insult and may play a protective role against colon cancer.

PERIPHERAL PLASMA CORTICOTROPIN‐RELEASING FACTOR CONCENTRATION DOES NOT CORRELATE WITH AUGMENTED COLONIC MOTILITY IN RESPONSE TO RESTRAINT STRESS IN RATS

1. Corticotropin-releasing factor (CRF) alters colonic motor function in response to restraint stress. It remains unclear whether peripheral CRF released by restraint stress correlates with stress-mediated colonic motility. 2. One strain gauge transducer was sutured on the serosal surface of the mid colon and a silastic cannula was inserted into the jugular vein. Seven days after surgery, the wires from the transducers were connected to the recording system and colonic motility was recorded. Rats were subjected to restraint stress for 90 min and blood samples were obtained every 30 min. 3. Immediately after the start of stress loading, phasic contractions were observed that lasted during restraint stress loading. Intracisternal injection of CRF elicited rapid augmentation of colonic motility, similar to that of restraint stress. 4. The plasma CRF concentration (4 pg/mL) remained unaltered within the first 30 min after stress loading, but increased gradually to 23 pg/mL at 90 min after the beginning of restraint stress. There was no positive correlation observed between plasma CRF concentrations and restraint stress-stimulated colonic motility. 5. These findings indicate that central CRF has a predominant role in stress-induced augmentation of colonic motility. It remains unclear whether a delayed response of plasma CRF concentrations in response to restraint stress is involved in mediating colonic motility.

Blueberry consumption inhibits gastrointestinal tumorigenesis in AOM‐treated rats

Epidemiological studies show inverse or no association of fruit consumption with relative risk for colorectal cancers. Such studies did not examine specific fruits and in particular, those enriched in polyphenols with high antioxidant capacities. We examined blueberry (BB), a fruit rich in anthocyanins and proanthocyanidins, for effects on gastrointestinal cancers in AOM‐treated Sprague‐Dawley rats. AIN93G diets containing no or 10% freeze‐dried BB were fed to rats over their lifetime. Rats received AOM at days 53 and 60 of age, with colon aberrant crypt foci (ACF) and gastrointestinal tumors quantified 6 and 17 weeks later, respectively. BB decreased ACF (by 24%, P=0.093) in males and increased ACF (31%, P=0.064) in females. Tumor incidence was reduced by BB in mid colon and proximal small intestine of male rats, resulting in a lower (26%, P=0.081) overall intestinal tumor incidence. In all intestine regions, female rats had reduced tumor incidence (∼70%, P&lt;0.001) relative to control males, with no effects of BB manifested. Females had more adenomas (as a proportion of total tumor number) than did males. BB favored (P&lt;0.05) greater adenoma/total tumor ratio in females. Results indicate inhibitory effects of BB on tumor initiation in AOM‐treated male rats and adenoma to adenocarcinoma transition in female rats, thus warranting further studies of BB on colorectal cancer. Supported by CRIS 6251‐51000‐005‐03S

Dietary inulin supplementation does not promote colonic iron absorption in a porcine model of anemia

Anemic weaner pigs surgically fitted with cecal cannulas were fed a low iron corn-soy ration supplemented with or without 4% inulin (Raftilose Synergy, Orafti) for 5 weeks. On 7 consecutive days in week 4, pigs were administered 1mg 54Fe in the morning feed followed 6 hours later by a 0.5mg 58Fe cannula infusion to measure total and colonic iron absorption, respectively. Whole blood was drawn prior to the initial dosing and 14 days thereafter for hemoglobin measurement and stable isotope detection using mass spectrometry. After 5 weeks, pigs were euthanased to isolate lumen content from the jejunum, ileum, cecum, and proximal, mid and distal colon for microbial profiling using terminal restriction fragment length polymorphism (TRFLP). The prebiotic role of inulin was confirmed by increases in lactobacilli and bifidobacteria with concomitant reductions in clostridia and enterobacteria in all 4 large intestinal compartments of inulin-fed pigs compared to controls. Surprisingly, a similar prebiotic effect also occurred in the jejunum. Hemoglobin levels were similar between both diet groups. Total iron absorption was 25.8 ± 3.4 and 16.0 ± 2.4% in inulin supplemented and control pigs, respectively (P > 0.05), while colonic iron absorption was 0.4 ± 0.1 and 0.2 ± 0.1%, respectively (P > 0.05). These results suggest that the colon does not make a significant contribution to total iron absorption in anemic individuals.

Hydrolysis site and action mode of supplemental dietary inulin in gastrointestinal tract of weanling pigs

We have previously shown a positive effect of supplemental inulin on bioavailability of intrinsic Fe in a corn-soybean meal basal diet (BD) for weanling pigs. Two experiments were conducted to determine mechanisms for that benefit of inulin. In Exp. 1, 12 pigs (7.7 ± 0.2 kg BW) were fed the low-iron (54 mg/kg) BD or BD + 4% inulin (Synergy 1, Orafti, Tienen, Belgium) for 6 wk. All pigs were killed at the end of the trial to collect digesta samples from stomach, upper and lower jejunum, cecum, and proximal, mid, and distal colon. Strikingly, inulin was detected only in digesta from the first three segments (0.4 to 5.5%, dry basis), but not from the large intestine of pigs fed inulin. Fructose concentrations in digesta from stomach and both parts of jejunum were greater (P < 0.05) in pigs fed inulin than those fed BD. To further determine if and how inulin was degraded mainly in ileum or cecum, we conducted Exp. 2 with 12 pigs (11.2 ± 1.1 kg BW) for 8 wk as did in Exp.1. except for that ileum instead of upper jejunum digesta samples were collected. Likewise, inulin was detected only in digesta from stomach, jejunum, and ileum of pigs fed inulin. Although inulianse activity was detectable in digesta from ileum, cecum, and proximal colon of both groups, the highest activity (P < 0.05) was found in the cecum digesta of pigs fed inulin. In conclusion, supplemental dietary inulin was degraded mainly in cecum where inulinase activity was induced by the supplementation. The elevated fructose concentration in the upper gut of pigs fed inulin might be beneficial for iron absorption.

Restraint stress stimulates colonic motility via central corticotropin-releasing factor and peripheral 5-HT3 receptors in conscious rats

Although restraint stress accelerates colonic transit via a central corticotropin-releasing factor (CRF), the precise mechanism still remains unclear. We tested the hypothesis that restraint stress and central CRF stimulate colonic motility and transit via a vagal pathway and 5-HT(3) receptors of the proximal colon in rats. (51)Cr was injected via the catheter positioned in the proximal colon to measure colonic transit. The rats were subjected to a restraint stress for 90 min or received intracisternal injection of CRF. Ninety minutes after the administration of (51)Cr, the entire colon was removed, and the geometric center (GC) was calculated. Four force transducers were sutured on the proximal, mid, and distal colon to record colonic motility. Restraint stress accelerated colonic transit (GC of 6.7 +/- 0.4, n=6) compared with nonrestraint controls (GC of 5.1 +/- 0.2, n=6). Intracisternal injection of CRF (1.0 microg) also accelerated colonic transit (GC of 7.0 +/- 0.2, n=6) compared with saline-injected group (GC of 4.6 +/- 0.5, n=6). Restraint stress-induced acceleration of colonic transit was reduced by perivagal capsaicin treatment. Intracisternal injection of CRF antagonists (10 microg astressin) abolished restraint stress-induced acceleration of colonic transit. Stimulated colonic transit and motility induced by restraint stress and CRF were significantly reduced by the intraluminal administration of 5-HT(3) antagonist ondansetron (5 x 10(-6) M; 1 ml) into the proximal colon. Restraint stress and intracisternal injection of CRF significantly increased the luminal content of 5-HT of the proximal colon. It is suggested that restraint stress stimulates colonic motility via central CRF and peripheral 5-HT(3) receptors in conscious rats.

Supplemental dietary inulin affects the bioavailability of iron in corn and soybean meal to young pigs.

Iron deficiency represents one of the most common global nutritional disorders in humans. Our objective was to determine whether and how supplemental inulin improved utilization of iron intrinsically present in a corn and soybean meal diet by young pigs for hemoglobin repletion. In Expt. 1, 3 groups (n = 8/group) of pigs were fed a corn and soybean meal-based diet (BD, without inorganic iron addition) or BD + 2 or 4% inulin (Synergy 1: a mixture of oligofructose and long-chain inulin HP, Orafti) for 5 wk. Final blood hemoglobin concentrations and the overall hemoglobin repletion efficiency of pigs were positively (r = 0.55 and 0.69, P < 0.01) correlated with dietary inulin concentrations. Compared with pigs fed the BD, those fed 4% inulin demonstrated a 28% improvement (P < 0.01) in hemoglobin repletion efficiency and 15% (P < 0.01) improvement in the final blood hemoglobin concentration. In Expt. 2, 12 weanling pigs (n = 6/group) were fed the BD or the BD + 4% inulin for 6 wk. Pigs fed 4% inulin had higher (P < 0.05) soluble Fe concentrations in the digesta of the proximal, mid, and distal colon, and lower (P < 0.05) sulfide concentrations in the digesta of the distal colon. Supplemental inulin had virtually no effect on pH or phytase activity of digesta from any of the tested segments. In conclusion, supplementing 4% inulin improved utilization of intrinsic iron in the corn and soybean meal diet by young pigs, and this benefit was associated with soluble Fe and sulfide concentrations but not pH or phytase activity in the digesta.

Intestinal morphology and enzymatic activity in newly weaned pigs fed contrasting fiber concentrations and fiber properties1

The main objective of this study was to determine the effect of fiber source and concentration on morphological characteristics, mucin staining pattern, and mucosal enzyme activities in the gastrointestinal tract of pigs. The experiment included 50 pigs from 10 litters weaned at 4 wk of age (BW 8.6 +/- 1.4 kg) and divided into 5 treatment groups. Diets containing fiber of various physico-chemical properties and concentrations were formulated to contain 73, 104, or 145 g of dietary fiber/kg of DM. The diets were based on raw wheat and barley flours. Pectin and barley hulls, representing soluble and insoluble fiber sources, respectively, were used to increase the fiber concentration. The pigs were fed the experimental diets for 9 d, and then the pigs were euthanized and the entire gastrointestinal tract was removed. Tissue samples were taken from the mid and distal small intestine and from the mid colon. Inclusion of pectin in the diets significantly decreased (P < 0.001) ADFI and ADG compared with pigs fed no pectin. The villi and the crypts were shorter in pigs fed pectin-containing diets, but the villous height/crypt depth ratio was unaltered. Pectin significantly decreased the area of mucins in the crypts of the small intestine, indicating that the pigs fed the pectin-containing diet would probably be more susceptible to pathogenic bacteria, although this cannot be separated from the impact on ADFI. The lectin-binding pattern of the intestinal mucosa was unaffected by diet. The activity of lactase and maltase was increased in pigs fed diets with high fiber content, whereas sucrase activity was increased in pigs fed the pectin-containing diets. The activity of the peptidases, aminopeptidase N and dipeptidylpeptidase IV, was increased when feeding high fiber diets, whereas the activity of gamma-glutamyl transpeptidase remained unaffected by the experimental diets. In conclusion, the reduced feed intake observed with the pectin-containing diets could explain the lower villous height and crypt depth observed in this study. However, direct effects of pectin also are possible, and thus further study is warranted. Feeding pigs high insoluble fiber diets improved gut morphology by increasing villi length and increased mucosal enzyme activity when compared with pigs fed pectin-containing diets. The mucin content as determined by staining characteristics suggests that pigs fed high insoluble fiber diets might be better protected against pathogenic bacteria than pigs fed diets high in soluble fiber.

Effect of Shiitake mushroom dose on colon tumorigenesis in azoxymethane-treated male Sprague-Dawley rats

We determined the effects of diets containing dry powdered Shiitake mushroom on frequency of azoxymethane-induced colon aberrant crypt foci (ACF) and intestinal tumors in male Sprague-Dawley rats. Pregnant rat dams and their progeny were fed AIN-93G diets containing casein (20%; control diet) or casein supplemented with Shiitake (1% or 4% wt/wt). Casein- and 1% Shiitake–fed rats exhibited identical growth curves, whereas those fed the 4% Shiitake diet were of slightly reduced body weight. The 4% Shiitake diet elicited increased active energy expenditure and reduced adiposity of rats. Small bowel and colon tumors and colon ACF were evaluated in the male progeny at 18 weeks after azoxymethane treatment. Aberrant crypt foci and tumors were most prevalent in the mid and distal regions of the colon. Shiitake intake had no effect on the relative incidence of tumors in the colon or small intestine (duodenum). Consumption of 1% Shiitake stimulated growth of invasive adenocarcinomas in the mid colon ( P < .005) and favored a nonsignificant increase in median frequency of ACF in this same region. In contrast, Shiitake at 4% intake elicited a reduction in colon tumor multiplicity. Results demonstrate stimulatory actions of 1% and inhibitory actions of 4% Shiitake mushroom on indices of rat colon tumorigenesis, which may be associated with altered metabolism.