Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “GASTROINTESTINAL TRACT”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
PubMed1989

Influence of specific gravity and food on movement of granules in the gastrointestinal tract of rats.

The suitability of rats as an animal model for estimating the bioavailability of controlled-release granules in humans was investigated. Non-disintegrating granules (diameter of 0.8 mm; specific gravity of 0.9-1.85) were used as a model preparation. Twenty granules were administered to fed rats, fasted rats and rats given soft food, and the number of granules remaining in the gastrointestinal tract was counted at suitable intervals. Granules with a specific gravity of 1.25 administered to fasted rats were rapidly emptied from the stomach with a 50% gastric emptying time of 1 h as compared with granules with a specific gravity of less than 1.0 or with a high specific gravity such as 1.85. The presence of food in the stomach reduced the emptying rate of granules. The mean transit time of granules through the small intestinal tract was not influenced by the specific gravity or the presence of food. The mean transit time was about 3 h. It was found that the transit profile of granules through the gastrointestinal tract in rats was similar to that of granules in humans. Accordingly, it is possible to use rats at the preformulation stage for estimating the bioavailability of controlled-release granules in humans.

Animals↗
PubMed2005

Acoustic radiation force impulse (ARFI) imaging of the gastrointestinal tract.

The evaluation of lesions in the gastrointestinal (GI) tract using ultrasound can suffer from poor contrast between healthy and diseased tissue. Acoustic Radiation Force Impulse (ARFI) imaging provides information about the mechanical properties of tissue using brief, high-intensity, focused ultrasound to generate radiation force and ultrasonic correlation-based methods to track the resulting tissue displacement. Using conventional linear arrays, ARFI imaging has shown improved contrast over B-mode images when applied to solid masses in the breast and liver. The purpose of this work is to (1) investigate the potential for ARFI imaging to provide improvements over conventional B-mode imaging of GI lesions and (2) demonstrate that ARFI imaging can be performed with an endocavity probe. ARFI images of an adenocarcinoma of the gastroesophageal (GE) junction, status-post chemotherapy and radiation treatment, demonstrate better contrast between healthy and fibrotic/malignant tissue than standard B-mode images. ARFI images of healthy gastric, esophageal, and colonic tissue specimens differentiate normal anatomic tissue layers (i.e., mucosal, muscularis and adventitial layers), as confirmed by histologic evaluation. ARFI imaging of ex vivo colon and small bowel tumors portray interesting contrast and structure that are not as well defined in B-mode images. An endocavity probe created ARFI images to a depth of over 2 cm in tissue-mimicking phantoms, with maximum displacements of 4 microm. These findings support the clinical feasibility of endocavity ARFI imaging to guide diagnosis and staging of disease processes in the GI tract.

Adenocarcinoma↗
PubMedDate not supplied

Sonography of the normal feline gastrointestinal tract.

The normal sonographic appearance of the stomach in various degrees of distension, the duodenum, the small intestine, and the large intestine was determined in awake and sedated cats. The mean stomach rugal fold thickness was 4.38 mm, and the interrugal thickness was 2.03 mm. No significant difference in stomach wall thickness was seen when the stomach was empty, half full, or full. The duodenal wall thickness was significantly greater than other parts of the small intestine, and this difference was accentuated by sedation (awake mean 2.4 mm; sedated mean 2.71 mm). The mean small intestinal wall thickness was 2.1 mm, and the mean colonic wall thickness was 1.67 mm. The five characteristic sonographic layers similar to that seen in the gastrointestinal tract of other species were routinely identified at all regions of the feline gastrointestinal tract.

Animals↗
PubMed2002

Expression of bitter taste receptors of the T2R family in the gastrointestinal tract and enteroendocrine STC-1 cells.

Although a role for the gastric and intestinal mucosa in molecular sensing has been known for decades, the initial molecular recognition events that sense the chemical composition of the luminal contents has remained elusive. Here we identified putative taste receptor gene transcripts in the gastrointestinal tract. Our results, using reverse transcriptase-PCR, demonstrate the presence of transcripts corresponding to multiple members of the T2R family of bitter taste receptors in the antral and fundic gastric mucosa as well as in the lining of the duodenum. In addition, cDNA clones of T2R receptors were detected in a rat gastric endocrine cell cDNA library, suggesting that these receptors are expressed, at least partly, in enteroendocrine cells. Accordingly, expression of multiple T2R receptors also was found in STC-1 cells, an enteroendocrine cell line. The expression of alpha subunits of G proteins implicated in intracellular taste signal transduction, namely Galpha(gust), and Galpha(t)-(2), also was demonstrated in the gastrointestinal mucosa as well as in STC-1 cells, as revealed by reverse transcriptase-PCR and DNA sequencing, immunohistochemistry, and Western blotting. Furthermore, addition of compounds widely used in bitter taste signaling (e.g., denatonium, phenylthiocarbamide, 6-n-propil-2-thiouracil, and cycloheximide) to STC-1 cells promoted a rapid increase in intracellular Ca(2+) concentration. These results demonstrate the expression of bitter taste receptors of the T2R family in the mouse and rat gastrointestinal tract.

Animals↗
PubMed1998

The expression of multidrug resistance protein in human gastrointestinal tract carcinomas.

BACKGROUND: Multidrug resistance protein (MRP) is a membrane phosphoglycoprotein with an Mr of 190,000 that is involved in the non-P-glycoprotein mediated multidrug resistance of human tumor cells. The aim of this study was to determine the clinicopathologic relevance of MRP expression in human gastrointestinal tract carcinomas. METHODS: The authors prepared a rabbit antiserum against MRP that does not cross-react with P-glycoprotein and retrospectively examined the expression of MRP in 86 squamous cell carcinomas of the esophagus, 103 adenocarcinomas of the stomach, and 139 colorectal adenocarcinomas by immunohistochemistry. None of the patients in this study had received prior chemotherapy. RESULTS: The proportion of MRP positive samples in the squamous cell carcinomas of the esophagus (62.8%, 54 of 86) was significantly higher than that in the adenocarcinomas of the stomach (34.1%, 35 of 103) and the colorectal adenocarcinomas (40.3%, 56 of 139) (P <0.01). The proportion of MRP positivity in the well-differentiated carcinomas was significantly higher than that in moderately or poorly differentiated carcinomas. MRP expression was independent of gender, lymph node metastasis, and tumor progression. CONCLUSIONS: These data indicate that the expression of MRP is correlated with the differentiation of carcinoma cells in the gastrointestinal tract and may be involved in the intrinsic drug resistance of well-differentiated squamous cell carcinoma of the esophagus.

ATP-Binding Cassette Transporters↗
PubMed1993

Antigenotoxic properties of lactic acid bacteria in vivo in the gastrointestinal tract of rats.

In view of the high incidence of dietary-related tumors, one important research goal is to identify the participating genotoxic carcinogens and the nutritional factors that may counteract their activities. We therefore have further developed a method to assess DNA damage in tumor target tissues of the gastrointestinal tract. Subsequently the prevention of this inducible DNA damage by lactic acid bacteria and by milk products fermented with probiotics was studied as well. The microgel electrophoresis technique was applied to cells of the esophageal, gastric, duodenal, and colonic mucosa. Cells were grouped according to their degree of DNA damage, the simplest measure of which is to discriminate between those with damage (comets) and those without damage. When these cells were isolated from animals treated with a genotoxic carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and exposed to MNNG for 1-24 hours, it was possible to follow the course of genotoxicity throughout the gastrointestinal tract. After the animals were treated with the lactic acid bacteria under study, it was possible to detect antigenotoxic properties as well. The gavage of 10(10) viable Lactobacillus casei cells in 10 ml of 0.9% NaCl per kilogram body weight immediately before the oral administration of MNNG (5 mg/kg body wt) resulted in a reduction of induced DNA damage in gastric and colonic mucosa cells. A sequential treatment schedule was even more effective: when the animals were treated orally with lactic acid bacteria or yogurt (10 ml/kg body wt) in the morning followed by MNNG (7.5 mg/kg body wt) eight hours later and the colon cells were isolated 16 hours later, the percentages of cells remaining intact were distinctly higher in the combination groups (68 +/- 10 and 68 +/- 19 for L. casei and a "Bio" yogurt, respectively) than in the group receiving only MNNG (45 +/- 17). The effect of heating L. casei was studied and was found to yield less clear-cut effects in preventing genotoxicity. The method is an efficient tool to elucidate antigenotoxic properties of food components in vivo in those target tissues actually afflicted by dietary-related tumors.

Animals↗
PubMed1993

Localization of drug release sites from an oral sustained-release formulation of 5-ASA (Pentasa) in the gastrointestinal tract using gamma scintigraphy.

Release of 5-ASA from a sustained release formulation (Pentasa, Ferring A/S, Copenhagen, Denmark) was monitored with plasma sampling for up to 24 hours in nine volunteers under both fasted and fed conditions. Drug absorption was correlated with location of the sustained-release microgranules in the gastrointestinal tract by gamma scintigraphy. Disintegration of the labeled tablet preparation occurred in the stomach within 20 minutes and acetylated 5-ASA was detectable in the plasma less than 60 minutes after ingestion. No significant differences were detected in either transit times through the small intestine, peak plasma acetylated 5-ASA concentration or lag time to absorption between fasted and fed individuals. Peak plasma concentration of acetylated 5-ASA usually occurred when the microgranules were present in the small intestine or ascending colon. The pharmacoscintigraphic study confirmed that 5-ASA release from the formulation occurred throughout the gastrointestinal tract, and that food effects on the in vivo behavior of the preparation were minimal.

Administration, Oral↗
PubMed1998

Ultrastructure of Helicobacter trogontum in culture and in the gastrointestinal tract of gnotobiotic mice.

Helicobacter trogontum is a micro-aerophilic urease-positive bacterium that has recently been isolated from the intestinal mucosa of rats. The purpose of this investigation was to study the ultrastructural details of this micro-organism in both pure culture and in the gastrointestinal tract of germ-free mice infected with H. trogontum. The micro-organism was a fusiform to slightly spiral gram-negative cell, 4-6 microm long and 0.6-0.7 microm wide, with four to seven bipolar sheathed flagella. The cytoplasm presented several irregular and also globular granules. On each side of the polar regions of the cells, there was a highly electron-dense band, the 'polar membrane'. Coccoidal forms were seen in old cultures. H. trogontum showed several ultrastructural characteristics of the Helicobacter genus and much resemblance to H. rappini and H. bilis. H. trogontum mainly colonised the large bowel of the gnotobiotic mice where it could be seen in the lumen and also inside the enterocytes. Vacuolation of the ileal epithelial cells, loss of microvilli and pronounced desquamation of the enterocytes of the caecum were observed in the bowel colonised by the bacterium. These observations raise the possibility that H. trogontum could cause some harm to the host at least in particular circumstances such as when it colonises the gastrointestinal tract of a germ-free host.

Animals↗
PubMed2006

Conjugative transfer facilitates stable maintenance of IncP-1 plasmid pKJK5 in Escherichia coli cells colonizing the gastrointestinal tract of the germfree rat.

Quantitative determination of IncP-1 plasmid loss from Escherichia coli cells colonizing the gastrointestinal tracts of germfree rats was achieved by flow cytometry. Results show that the plasmid's ability to conjugate counteracts plasmid loss and is thus an important mechanism for the stable maintenance of IncP-1 plasmids within the gastrointestinal environment.

Animals↗
PubMed1987

Smooth muscle tumours of the upper gastrointestinal tract.

Forty-six patients with smooth muscle tumours of the stomach and small intestine were treated surgically at the Princess Alexandra Hospital between 1970 and 1986. Leiomyomas were three times more common than leiomyosarcomas, but malignant tumours occurred more frequently in the small intestine than in the stomach. Gastric tumours tended to present with gastrointestinal bleeding, in contrast to intestinal lesions which presented predominantly with abdominal pain. Although leiomyomas tend to be smaller at operation than leiomyosarcomas, the size of a smooth muscle tumour is not reliable in discriminating between benign and malignant lesions. Therefore all smooth muscle tumours of the upper gastrointestinal tract should be excised as widely as possible, including local lymphatics in the dissection where practicable, so as to maximize the likelihood of radical extirpation of malignant lesions. Approximately one-third of patients with leiomyosarcomas have metastases at the time of surgery; the 5 year survival rate after surgical treatment of leiomyosarcomas of the upper gastrointestinal tract is less than 50%.

Adolescent↗
PubMed2006

The effect of haem in red and processed meat on the endogenous formation of N-nitroso compounds in the upper gastrointestinal tract.

Red and processed meat (PM) consumption increases the risk of large bowel cancer and it has been demonstrated that haem in red meat (RM) stimulates the endogenous production of N-nitroso compounds (NOCs) within the human intestine. To investigate whether N-nitrosation occurs in the upper gastrointestinal tract, 27 ileostomists were fed diets containing no meat, or 240 g RM or 240 g PM in a randomly assigned crossover intervention design carried out in a volunteer suite. Endogenous NOC were assessed as apparent total N-nitroso compounds (ATNC) in the ileostomy output. ATNC concentration in the diets was 22 microg ATNC/kg (RM) and 37 microg ATNC/kg (PM), and 9 microg ATNC/kg in the no meat diet. Levels significantly increased to 1175 microg ATNC/kg SEM = 226 microg ATNC/kg) following the RM (P=0.001) and 1832 microg ATNC/kg (SEM=294 microg ATNC/kg) following PM (P<0.001) compared to the no meat diet (283 microg ATNC/kg, SEM=74 microg ATNC/kg). ATNC concentrations in the ileal output were equivalent to those measured in faeces in similarly designed feeding studies. Supplementation with either 1 g ascorbic acid or 400 IU alpha-tocopherol had no effect on the concentration of ATNC detected in the ileal output. In in vitro experiments, N-nitrosomorpholine (NMor) was formed in the presence of nitrosated haemoglobin, at pH 6.8 but not in the absence of nitrosated haemoglobin. These findings demonstrate that haem may facilitate the formation of NOC in the absence of colonic flora in the upper human gastrointestinal tract.

Animals↗
PubMedDate not supplied

The effects of alpha-lactalbumin and whey protein concentrate on alpha-amino acids, calcium and phosphorus levels in blood and gastrointestinal tract of rats.

The effects of two dietary proteins on alpha-amino acids, calcium and phosphorus concentrations in plasma, stomach and intestine were investigated in rats trained to consume, in a single two-hour daily meal, diets containing a-lactalbumin (alpha-la) or whey protein concentrate (WPC) for two weeks. The results indicated that the concentrations of calcium and phosphorus in the gastrointestinal tract and that of a-amino acids in portal vein were not significantly influenced by the nature of diets. The amount of alpha-amino acids in the gastrointestinal tract of rats fed on WPC diet was significantly (p < 0.001) higher than that of alpha-la group. The levels of insoluble calcium and insoluble phosphorus in the small intestine were significantly (p < 0.001) higher in alpha-la group than in WPC group. These results indicated that the kinetics of alpha-amino acids, calcium and phosphorus were differently influenced by the nature of diet ingested, the sampling time and the sites of sample collections.

Amino Acids↗
PubMed1975

A histochemical method of differentiating lower gastrointestinal tract mucin from other mucins in primary or metastatic tumours.

Epithelial mucins of the normal terminal ileum, caecum, colon, and rectum of man are unique in that they alone exhibit staining following the periodate-borohydride/KOH/PAS technique. Application of this technique enables one to differentiate those mucin-producting metastases arising from adenocarcinoma of the lower gastrointestinal tract from those arising elsewhere, and may occasionally be useful in determining the site of the primary tumour when it is in doubt. Furthermore, it was found to be especially useful in distinguishing between primary adenocarcinoma of the lung and metastases in the lung from adenocarcinoma of the lower gastrointestinal tract.

Adenocarcinoma↗
PubMed1997

Enteropathogenic Escherichia coli protein secretion is induced in response to conditions similar to those in the gastrointestinal tract.

The pathogenicity of enteropathogenic Escherichia coli (EPEC) is associated with the expression and secretion of specific bacterial factors. EspB is one such secreted protein which is required to trigger host signaling pathways resulting in effacement of microvilli and cytoskeletal rearrangements. These events presumably contribute to the ensuing diarrhea associated with EPEC infections. EPEC encounters several environmental changes and stimuli during its passage from the external environment into the host gastrointestinal tract. In this paper we show that the secretion of EspB is subject to environmental regulation, and maximal secretion occurs under conditions reminiscent of those in the gastrointestinal tract. Thus, secretion is maximal at 37 degrees C, pH 7, and physiological osmolarity. In addition, maximal secretion requires the presence of sodium bicarbonate and calcium and is stimulated by millimolar concentrations of Fe(NO3)3. The secretion of the four other EPEC-secreted proteins appears to be modulated in a manner similar to that of EspB. Our results also show that secretion is not dependent on CO2, as originally reported by Haigh et al. (FEMS Microbiol. Lett. 129: 63-67, 1995), but that CO2 more likely acts as a component of the medium buffering system, since CO2 dependence was abolished by the use of alternative buffers.

Ammonium Chloride↗
PubMed2002

Serotonergic modulation of visceral sensation: upper gastrointestinal tract.

Agents that modify serotonergic function have therapeutic potential for the treatment of visceral hypersensitivity, either through a direct effect on perception or through modulation of visceral tone or motility. Administration of selective serotonin reuptake inhibitors reduces oesophageal sensitivity to distension but not gastric sensitivity to distension. 5-HT ligands may also influence gastric mechanosensitivity by altering tone. Although the exact role of 5-HT receptors in the control of gastrointestinal functions remains unknown, 5-HT is generally considered to be the main candidate involved in the modulation of motor and sensory function from the gastrointestinal tract. Hence serotonergic modulation of upper gut sensitivity appears to be promising for the development of novel approaches to the treatment of functional disorders of the upper gastrointestinal tract.

Animals↗
PubMed1979

Phenothiazine effect on gastrointestinal tract function.

Clinical evidence indicates that phenothiazines, specifically chlorpromazine (CPZ), used extensively in the treatment of patients with mental and/or neurologic disorders produce an ileus characterized by pseudoobstruction with an extended barium transit time of eight to ten days. Postoperatively, these patients have a protracted ileus, lasting from ten to fourteen days. In our present study we investigated the mechanism of action by which phenothiazines block gastrointestinal tract function as well as the possible reversal of this effect by pharmacologic agents. Guinea pigs were injected intraperitoneally with CPZ at a dose of 30 mg/kg/day for five to seventeen days. This caused deleterious effects in the gastrointestinal tract, such as cessation of peristalsis of small intestine and colon, and marked distension of the cecum. In vitro pharmacologic studies were performed on the electrically stimulated longitudinal muscle-myenteric plexus of the guinea pigs. We found that phenothiazines interfered with the neuromuscular mechanism of the intestine, as exemplified by a lack of response to electrical current stimulation. The effect was protracted, lasting at least 24 hours. These effects were reversed by the administration of the anticholinesterase, physostigmine (PGM), provided the block was less than 80 per cent. The paralytic ileus produced was similar to that found in man.

Animals↗
PubMed1991

The effect of site of administration in the gastrointestinal tract on the absorption of insulin from nanocapsules in diabetic rats.

Isobutylcyanoacrylate nanocapsules have been used as drug carriers for the enteral absorption of insulin. Their absorption has been studied by measuring fasted glycaemia in streptozotocin-induced diabetic rats after a single administration of encapsulated insulin (100 units kg-1) at various sites along the gastrointestinal tract. Glycaemia decreased from the second day, the intensity and duration depending on the site of administration (65% ileum, 59% stomach, 52% duodenum and jejunum, 34% colon). This hypoglycaemic effect lasted up to the 18th day after administration for ileum and jejunum, the 15th day for stomach and duodenum, and the 13th day for colon. In-vitro, nanocapsules protect insulin against proteolysis from pepsin, chymotrypsin and trypsin. These results suggest (i) that insulin is protected by nanocapsules in the gastrointestinal tract, (ii) that it is absorbed in an active form, and (iii) that ileum is the most potent site of absorption.

Animals↗