Carcinogenesis of the upper gastrointestinal tract induced by N-methyl-N '-nitro-nitrosoguanidine and reflux of duodenal contents in the rat

Purpose: To investigate the combined effects of reflux of duodenal contents through the pylorus and treatment with N-methyl-N'-nitro-nitrosoguanidine ( MNNG) on the development of lesions in the glandular stomach, at the gastrojejunal anastomosis and in the forestomach of rats. Methods: Eighty Male Wistar rats were divided into 4 groups: G1: MNNG + Reflux, G2: Reflux, G3: MNNG and G4: Gastrostomy. MNNG was given in the drinking water ( 100 mg/ml) for 12 weeks and then two groups ( G1 and G2) were submitted to a gastrojejunal anastomosis followed by section of the afferent loop and suture of both stumps to allow reflux of duodenal contents through the pylorus. The animals were sacrificed 18 and 36 weeks after surgery. The lesions obtained in the antral mucosa, at the gastrojejunal anastomosis and in the forestomach were analysed histologically. Results: Duodenal reflux induced proliferative lesions at both glandular and squamous mucosa of the stomach. In the antrum, adenomatous hyperplasia (AH) was observed in 20% and 50% of the animals at the 18(th) and 36(th) weeks respectively. Aditionally 85% of the animals presented AH at the gastrojejunal anastomosis and 60% developed squamous hyperplasia at the squamous portion of the stomach. MNNG treatment plus duodenal reflux enhanced the development of malignant tumors at both glandular and squamous mucosa, since there were 30% of antral adenocarcinomas and 45% of squamous carcinomas at the 18th week and the frequency of these malignant tumors rose to 50% in the antrum and 65% in the squamous mucosa at the 36th week. Conclusion: The reflux of duodenal contents through the pylorus enhanced the development of proliferative lesions, benign and malignant, in the glandular stomach and in the forestomach of rats.

Enteric coated magnetic HPMC capsules evaluated in human gastrointestinal tract by AC biosusceptometry

Purpose. To employ the AC Biosusceptometry (ACB) technique to evaluate in vitro and in vivo characteristics of enteric coated magnetic hydroxypropyl methylcellulose (HPMC) capsules and to image the disintegration process.Materials and Methods. HPMC capsules filled with ferrite (MnFe2O4) and coated with Eudragit (R) were evaluated using USP XXII method and administered to fasted volunteers. Single and multisensor ACB systems were used to characterize the gastrointestinal (GI) motility and to determine gastric residence time (GRT), small intestinal transit time (SITT) and orocaecal transit time (OCTT). Mean disintegration time (t (50)) was quantified from 50% increase of pixels in the imaging area.Results. In vitro and in vivo performance of the magnetic HPMC capsules as well as the disintegration process were monitored using ACB systems. The mean disintegration time (t (50)) calculated for in vitro was 25 +/- 5 min and for in vivo was 13 +/- 5 min. In vivo also were determined mean values for GRT (55 +/- 19 min), SITT (185 +/- 82 min) and OCTT (240 +/- 88 min).Conclusions. AC Biosusceptometry is a non-invasive technique originally proposed to monitoring pharmaceutical dosage forms orally administered and to image the disintegration process.

The impact of physical exercise on the gastrointestinal tract

Purpose of reviewPhysical exercise can be both beneficial and harmful for the gastrointestinal tract in a dose-effect relationship between its intensity and health. Mild-to-moderate intensity exercises play a protective role against colon cancer, diverticular disease, cholelithiasis and constipation, whereas acute strenuous exercise may provoke heartburn, nausea, vomiting, abdominal pain, diarrhea and even gastrointestinal bleeding. This review focuses on mechanisms involved in those symptoms and their associations with type of exercises in humans.Recent findingsOne quarter to one half of elite athletes are hampered by the gastrointestinal symptoms that may deter them from participation in training and competitive events. Vigorous exercise-induced gastrointestinal symptoms are often attributed to altered motility, mechanical factor or altered neuroimmunoendocrine secretions. Training, lifestyle modifications, meal composition, adequate hydration and avoidance of excessive use of some medications are the recommendations.SummaryStrenuous exercise and dehydrated states would be the causes of gastrointestinal symptoms referred by 70% of the athletes. Gut ischemia would be the main cause of nausea, vomiting, abdominal pain and (bloody) diarrhea. The frequency is almost twice as high during running than during other endurance sports as cycling or swimming and 1.5-3.0 times higher in the elite athletes than the recreational exercisers.

Posthatching water and feed deprivation affect the gastrointestinal tract and intestinal mucosa development of broiler chicks

We studied the effect of feed and water deprivation on gastrointestinal tract and intestinal mucosa development of chicks at 24, 48, and 72 h posthatching. The treatments were water and feed ad libitum, water ad libitum and no feed, no water but feed ad libitum, and no water and no feed. The relative weight of the yolk sac was not influenced by the treatments. However, at 48 and 72 h posthatching, the relative weight of the liver increased, and the gizzard + proventriculus weight decreased in birds receiving feed ad libitum. An increase in jejunum and ileum relative weights and lengths was observed when the birds were supplied with feed and water. The lack of water produced the same effect as the lack of feed, both causing a higher number of villi per area with reduction in villus size, when compared with feed and water ad libitum treatments. The results of this study revealed that feed and water are able to affect intestinal villus development after hatching, indicating that both feed and water must be supplied to the chicks immediately after hatching.

CD34 EXPRESSION IN STROMAL TUMORS OF THE GASTROINTESTINAL-TRACT

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that may exhibit varied morphologic appearances (spindle, epithelioid) and biologic potentials. Given the continuing controversy regarding the type of cell differentiation present in these tumors (muscle versus nerve sheath versus null), we evaluated a set of GISTs, most of which had been previously examined for the presence of smooth muscle differentiation, for expression of CD34, a 115 kDa cell-surface progenitor cell marker also recently identified in a subset of mesenchymal tumors. Using antibody My 10 in deparaffinized, formalin-fixed tissue after pretreatment with microwave energy, we found that 46 of 57, or 81%, of GISTs were CD34+; this fraction of CD34+ tumors exceeded the fraction of these same GISTs found to show muscle actin (72%) expression. In addition, a consistently higher fraction of the tumor cell population was CD34+ than was muscle actin positive. These findings suggest that CD34 is a very sensitive marker for the identification of GISTs. CD34 is normally expressed by endothelial as well as perivascular cells, perhaps related to, but distinct from, vascular smooth muscle cells. While the nature of these latter cells is uncertain, the expression of CD34 in such a large fraction of GISTs may provide evidence of a unique differentiation pathway in these tumors.

Biological control of sheep parasite nematodes by nematode-trapping fungi: In vitro activity and after passage through the gastrointestinal tract

The main method used for the control of gastrointestinal nematodes in sheep production is the application of chemotherapeutic agents, which often lead to the selection of parasites resistant to given active principles. Biological control can be considered a promising alternative, contributing to an increase in the efficacy of verminous control. We determined the in vitro activity and in situ survival of the predatory fungi Arthrobotrys musiformis and Arthrobotrys conoides during passage through the gastrointestinal tract of sheep after oral administration of conidia in microencapsulated form and as a liquid in natura. Initial in vitro tests showed that both fungi were efficient in the predation of trichostrongylid L3 larvae present in the faeces of sheep naturally infected with gastrointestinal nematodes. The fungi presented high nematophagous activity, which was 99.3% for A. conoides and 73.7% for A. musiformis. A. conoides did not survive passage through the gastrointestinal tract under the conditions of the present experiment. On the other hand, A. musiformis was reisolated after administration in either microencapsulated or liquid form, suggesting that this species is a promising alternative for the control of nematodes in sheep since it survives without any protection (in natura). © Springer 2005.

Magnetic images of pharmaceutical dosage forms in the human gastrointestinal tract

Oral administration with solid dosage forms is a common route in the drug therapy widely used. The drug release by the disintegration process occurs in several gastrointestinal tract (GIT) regions. AC Biosusceptometry (ACB) was originally proposal to characterize the disintegration process of tablets in vitro and in the human stomach, through changes in magnetic signals. The aim of this work was to employ a multisensor ACB system to monitoring magnetic tablets and capsules in the human GIT and to obtain the magnetic images of the disintegration process. The ACB showed accuracy to quantify the gastric residence time, the intestinal transit time and the magnetic images allowed to visualize the disintegration of magnetic formulations in the GIT. The ACB is a non-invasive, radiation free technique, completely safe and harmless to the volunteers and had demonstrated potential to evaluate pharmaceutical dosage forms in the human gastrointestinal tract. © 2005 IEEE.

A novel device with 36 channels for imaging and signal acquisition of the gastrointestinal tract based on AC biosusceptometry

The alternate current biosusceptometry (ACB) is a biomagnetic technique used to study some physiological parameters associated with gastrointestinal (GI) tract. For this purpose it applies an AC magnetic field and measures the response originating from magnetic marks or tracers. This paper presents an equipment based on the ACB which uses anisotropic magnetoresistive (AMR) sensors and an inexpensive electronic support. The ACB-AMR developed consists of a square array of 6x6 sensors arranged in a firstorder gradiometer configuration with one reference sensor. The equipment was applied to capture magnetic images of different phantoms and to acquire gastric contraction activity of healthy rats. The results show a reasonable sensitivity and spatial-temporal resolution, so that it may be applied for imaging of phantoms and signal acquisition of the GI tract of small animals. © 2010 IEEE.

Contribution of different segments of the gastrointestinal tract to digestion in growing Saanen goats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Organ-specific eosinophilic disorders of the skin, lung, and gastrointestinal tract

Eosinophils are multifunctional leukocytes that increase in various tissues in patients with a variety of disorders. Locally, they can be involved in the initiation and propagation of diverse inflammatory responses. In this review the clinical association of eosinophils with diseases of the skin, lung, and gastrointestinal tract is summarized. An approach to determining the causal role of eosinophils in these diseases is presented. Recent findings concerning molecular diagnosis, cause, and treatment are discussed.

Smoothelin is a specific and robust marker for distinction of muscularis propria and muscularis mucosae in the gastrointestinal tract

As tumour specimens and biopsy specimens become smaller, recognition of anatomical structures relevant for staging is increasingly challenging. So far no marker is known that reliably discriminates between muscularis propria (MP) and muscularis mucosae (MM) of the gastrointestinal tract. Recently, smoothelin expression has been shown to differ in MP and MM of the urinary bladder. We aimed to analyse the expression of smoothelin in the gastrointestinal tract in MP and MM in order to define a novel diagnostic tool to identify MM bundles.

Expression and function of 5-hydroxytryptamine 4 receptors in smooth muscle preparations from the duodenum, ileum, and pelvic flexure of horses without gastrointestinal tract disease

OBJECTIVE: To evaluate the expression of the 5-hydroxytryptamine 4 (5-HT4) receptor subtype and investigate the modulating function of those receptors on contractility in intestinal tissues obtained from horses without gastrointestinal tract disease. SAMPLE POPULATION: Smooth muscle preparations from the duodenum, ileum, and pelvic flexure collected immediately after slaughter of 24 horses with no history or signs of gastrointestinal tract disease. PROCEDURES: In isometric organ baths, the contractile activities of smooth muscle preparations in response to 5-hydroxytryptamine and electric field stimulation were assessed; the effect of tegaserod alone or in combination with 5-hydroxytryptamine on contractility of intestinal specimens was also investigated. Presence and distribution of 5-HT4 receptors in intestinal tissues and localization on interstitial cells of Cajal were examined by use of an immunofluorescence technique. RESULTS: Widespread 5-HT4 receptor immunoreactivity was observed in all intestinal smooth muscle layers; 5-HT4 receptors were absent from the myenteric plexus and interstitial cells of Cajal. In electrical field-stimulated tissue preparations of duodenum and pelvic flexure, tegaserod increased the amplitude of smooth muscle contractions in a concentration-dependent manner. Preincubation with tegaserod significantly decreased the basal tone of the 5-HT-evoked contractility in small intestine specimens, compared with the effect of 5-HT alone, thereby confirming that tegaserod was acting as a partial agonist. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, 5-HT4 receptors on smooth muscle cells appear to be involved in the contractile response of the intestinal tract to 5-hydroxytryptamine. Results suggest that tegaserod may be useful for treatment of reduced gastrointestinal tract motility in horses.

Gastrointestinal tract mucosal histomorphometry and epithelial cell proliferation and apoptosis in neonatal and adult dogs

In this study, the hypothesis was tested that the size of gastrointestinal tract (GIT) mucosal components and rates of epithelial cell proliferation and apoptosis change with increasing age. The aims were to quantitatively examine GIT histomorphology and to determine mucosal epithelial cell proliferation and apoptosis rates in neonatal (<48 h old) and adult (8 to 11.5 yr old) dogs. Morphometrical analyses were performed by light microscopy with a video-based, computer-linked system. Cell proliferation and apoptosis of the GIT epithelium were evaluated by counting the number of Ki-67 and caspase-3-positive cells, respectively, using immunohistochemical methods. Thickness of mucosal, glandular, subglandular, submucosal and muscular layers, crypt depths, villus heights, and villus widths were consistently greater (P < 0.05 to P < 0.001), whereas villus height/crypt depth ratios were smaller (P < 0.001) in adult than in neonatal dogs. The number of Ki-67-positive cells in stomach, small intestine, and colon crypts, but not in villi, was consistently greater (P < 0.01) in neonatal than in adult dogs. In contrast, the number of caspase-3-positive cells in crypts of the stomach, small intestine, and colon and in villi was not significantly influenced by age. In conclusion, canine GIT mucosal morphology and epithelial cell proliferation rates, but not apoptosis rates, change markedly from birth until adulthood is reached.