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At least 793 records · Page 44Linked to original sources
PubMed1992

Chemical characterization of vasoactive intestinal polypeptide-like immunoreactivity in ovine hypothalamus and intestine.

Two forms of pituitary adenylate cyclase activating polypeptides with 38 (PACAP38) and 27 residues (PACAP27) respectively were recently isolated from ovine hypothalamic tissues. The N-terminal 28 amino acids sequence of PACAP was found to have 68% homology with porcine vasoactive intestinal peptide (VIP). In order to determine whether the primary structure of VIP of ovine hypothalamus is identical with porcine VIP or similar to PACAP, VIP immunoreactivity as determined by radioimmunoassay for porcine VIP was isolated in a pure form from ovine hypothalamic extracts. VIP was also isolated from ovine intestine. Amino acid analysis as well as amino acid sequence analysis showed that ovine hypothalamic and intestinal VIP were identical to porcine VIP, but different from PACAP.

Adenylyl Cyclases↗
PubMed2004

Italian guidelines for intestinal transplantation: potential candidates among the adult patients managed by a medical referral center for chronic intestinal failure.

In 2002, the Italian guidelines for eligibility of patients for intestinal transplantation (ITx) were defined as: life-threatening complications of home parenteral nutrition (HPN), lack of venous access for HPN, locally invasive tumors of the abdomen, Chronic intestinal failure (CIF) with a high risk of mortality, primary disease-related poor quality of life (QoL) despite optimal HPN. Our aim was to identify potential candidates for ITx according to these national guidelines among patients managed by a medical referral center for CIF. Records of patients who received HPN were reviewed. CIF was considered reversible or irreversible (energy by HPN <50% or >50% basal energy expenditure). Patients with irreversible CIF were considered eligible for ITx in the absence of a contraindication, as are used for solid organs Tx. From 1986 to 2003 among 64 patients who met the entry criteria 23 showed reversible and 41 irreversible, CIF. Twenty-one patients with irreversible CIF had an indication for ITx, but eight had also contraindications; thus 13 were eligible, including intestinal pseudo-obstruction (n = 6), mesenteric ischemia (n = 3), Crohn's (n = 2), radiation enteritis (n = 1), and desmoid (n = 1). Indications for ITx included HPN liver failure (n = 2), lack of venous access (n = 2), CIF with high risk of mortality (n = 3), very poor QoL (n = 6 including 5 with pseudo-obstruction). According to the Italian guidelines for ITx, 31% of patients with irreversible CIF managed by a medical referral center were eligible for ITx. Primary disease-related poor QoL was the indication in half of them. Studies on the QoL after ITx are required to allow patients to make an educated decision.

Adult↗
PubMed1997

A blood test for intestinal permeability and function: a new tool for the diagnosis of chronic intestinal disease in dogs.

We demonstrate that rhamnose, 3-O-methyl-D-glucose, D-xylose and lactulose may be quantified accurately in blood by HPLC and pulsed amperometric detection, thus enabling studies of intestinal permeability and function to be carried out using plasma samples. Prior to HPLC, the endogenous glucose was enzymatically modified to gluconic acid and the protein precipitated. The precision of the quantification of the sugars in plasma (CV: 2.2-5.7%; 8.7-10.6% at very low concentrations) compared well with the quantification in urine. The results for groups of 8 dogs with small intestinal bacterial overgrowth and 12 dogs with inflammatory bowel disease were shown to be significantly different from a group of 20 normal control dogs (P < 0.001), demonstrating the test's value as a diagnostic tool. The normal ranges in blood 2 h post oral administration were determined to be 0.05-0.17 for the lactulose/rhamnose ratio and 0.45-0.65 for the xylose/3-O-methylglucose ratio. This method may be employed advantageously when the collection of urine in intestinal permeability and function tests is difficult.

3-O-Methylglucose↗
PubMed1997

Guanylin-, heat-stable enterotoxin of Escherichia coli- and vasoactive intestinal peptide-induced water and ion secretion in the rat intestine in vivo.

The heat-stable enterotoxin of Escherichia coli binds to an intestinal receptor, guanylyl cyclase-C, and produces cGMP to induce diarrhea. Guanylin is an endogenous ligand of this receptor. In the present in vivo study, the intestinal water and ion secretion induced by mucosal application of 2 nmol/ml guanylin or 5 or 10 units/ml heat-stable enterotoxin into closed loops was compared in the rat. The characteristics of secretion induced by cAMP following intravenous perfusion of 1.2 nmol/100 g per h vasoactive intestinal peptide were compared to those induced by cGMP. Unidirectional Na+ and Cl- fluxes were estimated by addition of 22Na into the loop and i.v. injection of 36Cl. Guanylin induced less water and ion secretion than that produced by heat-stable enterotoxin in the colon, confirming the results of in vitro studies, and also in duodenum and ileum. The cAMP- or cGMP-mediated response had a similar pattern, i.e., an inhibition of Na+ absorption and an increase in anion secretion.

Animals↗
PubMed1980

Study of kinetics of epithelial cell populations in normal tissues of the rat's intestines and in carcinogenesis. I. A comparison of enterocyte population kinetics in different segments of the small intestine and colon.

The peculiarities of enterocyte proliferation in the duodenum, jejunum, ileum, caecum, ascending, transverse and descending colon in the rat were studied by different methods of analysis of cell population kinetics (percentage-labelled mitosis curves, cumulative labelling curves, distribution of labelling index curves, etc.). The majority of proliferating cells in the small intestine are homogenous, as far as mitotic cycle mean duration (11-12 hrs) is concerned. All proliferating cells in all the zones of the colonic crypts and the bottom of the small intestine crypts are divided into subpopulations, having different mean durations of the mitotic cycle. It is suggested that, in the crypt bottom in all intestines as well as the crypt's maximum proliferation zones in most of the colonic segments, a considerable fraction of cells has a very long mitotic cycle or enters resting phase R1. The average value of the mean durations of the mitotic cycle of all colonic enterocyte subpopulations is 18-22 hours. On the basis of the authors' findings and literature data, a model for the enterocyte life cycle is proposed, according to which the cell flux is branched during the mitotic cycle and the crypt develops from a stem enterocyte population located at its bottom.

Animals↗
PubMed1989

Autonomic innervation of the intestine from a baby with megacystis microcolon intestinal hypoperistalsis syndrome: II. Electrophysiological study.

The pattern of spontaneous activity and innervation of the stomach, small intestine, and bladder obtained from a patient with megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) was studied in vitro, using tension recording and microelectrode techniques. We found that, compared with findings in the controls, autonomic inhibitory input to the smooth muscle cells of the small intestine was significantly decreased.

Autonomic Nervous System↗
PubMed1986

Treatment of distal intestinal obstruction syndrome in cystic fibrosis with a balanced intestinal lavage solution.

Conventional treatment of distal intestinal obstruction syndrome (DIOS) with high doses of pancreatic enzymes, mucolytic agents, and enemas is neither predictably effective nor rapid in action. In 6 cystic fibrosis patients with DIOS a balanced, non-absorbable intestinal lavage solution produced clinical and radiological improvement and striking improvement in DIOS scores. It is suggested that a balanced intestinal lavage solution should be considered as an alternative treatment for DIOS in patients with cystic fibrosis.

Adolescent↗
PubMed1987

The effects of different MNNG (N-methyl-N'-nitro-N-nitrosoguanidine)-doses on the stomach and the upper small intestine of the rat. II. The frequency of intestinal metaplasia.

N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was given to 3 groups of male Wistar rats in different doses of 25 micrograms/ml, 50 micrograms/ml and 100 micrograms/ml with their drinking water for 32 weeks. After 50 weeks the antrum region of the stomach was investigated by serial sections. All animals showed tubules with metaplastic intestinal epithelium. The different values of metaplastic glands in the antrum region of the stomach were 187 (25 micrograms MNNG), 76 (50 micrograms MNNG) and 51 (100 micrograms MNNG). They indicate an inverse relationship of the frequency of intestinal metaplasia and the MNNG dose. As opposed to this dose-response pattern, cytotoxic alterations, regenerative hyperplastic lesions and tumours of the stomach are more frequent after medium of high MNNG doses. It is therefore suggested that the induction of intestinal metaplasia is a specific effect of the carcinogen mainly in the low dose range.

Animals↗
PubMed1997

Restricted intestinal absorption of some beta-lactam antibiotics by an energy-dependent efflux system in rat intestine.

PURPOSE: The purpose of this study was to examine factors limiting the intestinal absorption of orally inactive beta-lactam antibiotics. METHODS: Permeation behaviors of various beta-lactam antibiotics across rat intestinal segments were evaluated in vitro using diffusion cells. RESULTS: Poorly absorbed beta-lactam antibiotics, like cephaloridine and cefoperazone, commonly exhibit greater serosal-to-mucosal permeation than mucosal-to-serosal permeation, while cephalexin permeation was greater in the mucosal-to-serosal direction. In the absence of D-glucose, secretory-oriented permeation of cephaloridine and cefoperazone disappeared. Addition of sodium azide into an experimental buffer including D-glucose significantly and selectively enhanced mucosal-to-serosal permeation of cephaloridine and cefoperazone. Although benzylpenicillin, ampicillin, and amoxicillin all showed secretory-oriented permeation, the tendency to permeation was greatest with benzylpenicillin and least with amoxicillin. Probenecid stimulated mucosal-to-serosal permeation of cephaloridine, but verapamil and p-aminohippuric acid had no significant effect on it. CONCLUSIONS: It has been suggested that mechanisms which induce secretory-oriented permeation of orally inactive beta-lactam antibiotics are factors limiting intestinal absorption of such antibiotics. This energy-demanding efflux system was distinct from P-glycoprotein-mediated transport. A free alpha-amino group in the molecule is an important factor for reducing an affinity with the efflux system.

Animals↗
PubMed1970

Glucose metabolism in the mucosa of the small intestine. Changes of hexokinase activity during perfusion of the proximal half of rat small intestine.

1. The effect of perfusion on the activities of hexokinase and lactate dehydrogenase was studied in the proximal half of the small intestine of fed and starved rats. 2. Perfusion of preparations from starved rats with a medium containing glucose caused a significant increase in hexokinase activity of the particle-free supernatant. The increase in activity was observed as early as 5min after the start of perfusion and persisted for up to 66min of perfusion. No increase in hexokinase activity of the particle-free supernatant was observed when a medium containing mannitol was used. As a further control, preparations from fed rats were perfused under the same conditions. With the medium containing glucose, the hexokinase activity of the particle-free supernatant remained unchanged during the first 15min of perfusion and thereafter fell gradually until, after 66min of perfusion, 73% of the original activity was retained. 3. The activity of lactate dehydrogenase in the particle-free supernatant prepared from the proximal half of the untreated small intestine of starved rats was significantly lower than in corresponding preparations from fed animals. However, it did not change significantly on perfusion with media containing either mannitol or glucose. 4. The distribution of hexokinase activity between total particulate fraction and particle-free supernatant was measured in preparations from starved rats after perfusion for 5-10min. In preparations that had not been perfused the ratio of hexokinase activity in total particulate fraction/particle-free supernatant was significantly higher in starved than in fed animals. After perfusion with a medium containing glucose, the total homogenate activity had not changed significantly, whereas the ratio of hexokinase activity in total particulate fraction/particle-free supernatant decreased significantly and approached the value obtained with fed animals. 5. The results agree with the view that the glucose-dependent increase of hexokinase activity in the soluble cell compartment as observed in vivo and in vitro in the intestinal mucosa of starved rats is brought about by a release of hexokinase activity from a particulate subcellular structure(s).

Animals↗
PubMed1985

The rat liver vasoactive intestinal peptide binding site. Molecular characterization by covalent cross-linking and evidence for differences from the intestinal receptor.

To identify the molecular components of the vasoactive intestinal peptide (VIP) binding sites in the liver, 125I-labelled VIP was covalently linked to liver membranes by using the cleavable cross-linker dithiobis(succinimidylpropionate). Purified rat liver plasma membranes were incubated with 125I-VIP, washed and treated with 1 mM-cross-linker. Polyacrylamide-gel electrophoresis of membrane proteins followed by autoradiography revealed a major 125I-VIP-protein complex of Mr 51 000. A minor Mr 89 000 complex was also observed. An identical pattern of protein labelling was obtained using crude membranes from rat liver. Labelling of the Mr 51 000 and 89 000 species was specific in that it could be abolished by native VIP, but was unaffected by 1 microM-glucagon and cholecystokinin octapeptide. Densitometric scanning of autoradiographs indicated that the labelling of the two species was abolished by similar low VIP concentrations (0.1-100 nM). It was also reduced by two VIP agonists, peptide histidine isoleucine amide and secretin, with a potency that is 1/7 and 1/200 that of native VIP, respectively. The guanine nucleotide GTP in the concentration range between 10(-7) and 10(-3) M reduces the labelling of the major Mr 51 000 protein and that of the minor Mr 89 000 protein, but with a slightly higher potency. Assuming one molecule of 125I-VIP was bound per molecule of protein, a major Mr 48 000 protein and a minor Mr 86 000 protein were identified as components of the high-affinity VIP binding sites in liver. This contrasts markedly with the pattern of labelling of rat intestinal epithelial membranes, where a Mr 73 000 protein was identified as a high-affinity VIP receptor and a Mr 33 000 protein as a low-affinity VIP binding site [Laburthe, Bréant & Rouyer-Fessard (1984) Eur. J. Biochem. 139, 181-187], suggesting structural differences between VIP binding sites in rat liver and intestinal epithelium.

Animals↗
PubMed1999

Vasoactive intestinal peptide suppresses migrating myoelectric complex of rat small intestine independent of nitric oxide.

The involvement of nitric oxide (NO) in the biological response to vasoactive intestinal peptide (VIP) on the migrating myoelectric complex (MMC) of small bowel and systemic arterial blood pressure was investigated in the rat. Animals were supplied with bipolar electrodes for electromyography of the small intestine and blood pressure was assessed by a pressure transducer connected to a carotid artery. In the first session, Nomega-nitro-L-arginine (L-NNA) was administered intravenously at 1, 2, 4 and 20 mg kg(-1). Effects of L-NNA at 1 and 20 mg kg(-1) were also studied after L-arginine 300 mg kg(-1). In the second session, intravenous infusion of VIP 500 pmol kg(-1) min(-1) was administered before and after L-NNA at 1 and 20 mg kg(-1). L-NNA at increasing doses stimulated myoelectric spiking of the small bowel until at 4 mg kg(-1) the MMC was disrupted and irregular spiking induced. Neither at 1 nor 20 mg kg(-1) did L-NNA affect the inhibitory motility response or decrease of blood pressure induced by VIP at a dose of 500 pmol kg(-1) min(-1). Our results show that effects of VIP on motility of the small intestine and systemic arterial blood pressure are direct and not dependent on NO as a common final link.

Animals↗
PubMed2000

Vasoactive intestinal polypeptide appears to be one of the mediators in misoprostol-enhanced small intestinal transit in rats.

BACKGROUND AND AIMS: Prostaglandin analogs have the pharmacologic effect of speeding up small intestinal transit (SIT). It remains unknown whether some gut peptides also mediate this enhancement. We studied the effect of misoprostol on rat SIT and looked at the role of vasoactive intestinal polypeptide (VIP) release during its action. METHODS: A group of rats initially received oral misoprostol treatment of 1, 10, 50 and 100 microg/kg, respectively. By using orally fed charcoal as a motility marker, the SIT was assessed at 30 min following oral misoprostol treatment. Another group of rats received misoprostol as an intraperitoneal injection in similar doses to the group above. The small intestinal transit was computed for this group at 30 min following misoprostol injection via an instilled radiochromium motility marker that went through a previously placed intraduodenal catheter. The plasma VIP level was measured by using a radioimmunoassay kit. RESULTS: Neither charcoal evaluated transit nor the plasma VIP level was influenced by the lower doses of oral misoprostol treatment (1 and 10 microg/kg), whereas other doses enhanced SIT and diminished the plasma VIP level (P< 0.01).The similar effects on radiochromium computed SIT (P< 0.01) and plasma VIP levels were obtained in tubed rats following misoprostol intraperitoneal treatment. The SIT results correlated negatively with plasma VIP levels. CONCLUSIONS: Enhanced SIT and diminished VIP levels are found in rats following misoprostol treatment. It appears that inhibited VIP release is one of the mechanisms in misoprostol-enhanced SIT.

Administration, Oral↗
PubMed2000

Unique epithelial cell production of hepatocyte growth factor/scatter factor by putative precancerous intestinal metaplasias and associated "intestinal-type" biliary cancer chemically induced in rat liver.

Recently, we observed that Met, the receptor for hepatocyte growth factor/scatter factor (HGF/SF), is overexpressed in epithelial cells of both early-appearing intestinal metaplastic glands in precancerous hepatic cholangiofibrotic tissue and neoplastic glands in later developed intestinal-type of cholangiocarcinoma originated from the furan rat model of cholangiocarcinogenesis when compared with normal and hyperplastic intrahepatic biliary epithelia. We now show that HGF/SF is also aberrantly expressed in a manner closely paralleling that of its receptor in the neoplastic epithelial cells of furan-induced rat cholangiocarcinomas and in a majority of metaplastic epithelial cells within earlier formed precancerous hepatic cholangiofibrotic tissue. Using in situ hybridization and reverse transcription-polymerase chain reaction (RT-PCR), we further showed specific expression of HGF/SF messenger RNA (mRNA) in a novel rat cholangiocarcinoma epithelial cell line overexpressing Met. This cholangiocarcinoma cell line, termed C611B, was established from tumorigenic cells isolated from a furan-induced transplantable tumor. Moreover, we detected by in situ hybridization strong expression of HGF/SF mRNA transcripts in the cancerous epithelial glands of cholangiocarcinoma developed in recipient rats after in vivo cell transplantation of C611B cells. In contrast, mRNA transcripts and protein immunoreactivity for this cytokine were not detected in hepatocytes and biliary epithelial cells in adult normal rat liver nor in rat hyperplastic intrahepatic biliary epithelium. Our results clearly show that HGF/SF becomes aberrantly expressed in cholangiocarcinoma epithelium and in putative precancerous intestinal metaplastic epithelium induced in the liver of furan-treated rats.

Animals↗
PubMed1994

Vasoactive intestinal peptide-receptor imaging for the localization of intestinal adenocarcinomas and endocrine tumors.

BACKGROUND: Intestinal adenocarcinomas and various endocrine tumors express large numbers of high-affinity receptors for vasoactive intestinal peptide (VIP). We have evaluated the usefulness of scanning with VIP labeled with iodine-123 for tumor localization in patients with gastrointestinal tumors. METHODS: Radioiodinated VIP was purified by high-pressure liquid chromatography and administered as a single intravenous bolus injection (300 pmol [1 microgram]). Scanning with radiolabeled VIP was compared with computed tomography and scanning with somatostatin analogues in 79 patients with colorectal cancer, pancreatic carcinoma, gastric cancer, carcinoid tumor, or insulinoma. RESULTS: Visualization of gastrointestinal tumors and metastases was obtained with radiolabeled VIP. Binding of the labeled peptide by primary tumors and metastases was visible shortly after the injection and was still demonstrable at 24 hours. In patients with colorectal adenocarcinomas, primary or recurrent tumors were visualized in 10 of 10, liver metastases in 15 of 18, lung metastases in 2 of 3, and lymph-node metastases in 4 of 4. Primary pancreatic adenocarcinomas were visualized by imaging in 10 of 12 patients, and liver metastases were seen in 7 of 7. Primary or recurrent gastric adenocarcinomas were visualized in 5 of 5 patients, and liver metastases were seen in 2 of 2 patients. VIP scans were positive in 9 of 10 patients with carcinoid tumors and in 4 of 4 patients with insulinomas. Some tumors with positive VIP scans were also visualized with somatostatin analogues (4 of 17 colorectal adenocarcinomas, 8 of 9 carcinoids, and 2 of 2 insulinomas). In vitro binding studies confirmed the presence of VIP receptors on gastrointestinal tumors. CONCLUSIONS: Scanning with radiolabeled VIP can visualize intestinal tumors and metastases that express receptors for VIP.

Adenocarcinoma↗
PubMed2005

Thiazide-sensitive NaCl-cotransporter in the intestine: possible role of hydrochlorothiazide in the intestinal Ca2+ uptake.

Thiazides, such as hydrochlorothiazide (HCTZ), are used to control blood pressure and to reduce renal calcium excretion. These effects are a result of interactions with the NaCl-cotransporter (NCC). This is demonstrated by the fact that mutations within the NCC protein lead to salt-resistant hypotension and hypocalciuria, paralleled by an increase in bone mineral density. These symptoms are also known as Gitelman syndrome. It has become increasingly evident that the effect of HCTZ on blood pressure and calcium homeostasis cannot be attributed exclusively to kidney functions, where the primary action of HCTZ on NCC is postulated to occur. We demonstrated the presence of the NCC transporter in the rat small intestine (ileum and jejunum) and human HT-29 cells, by using reverse transcription-PCR, Northern blot, Western blot, and immunofluorescence. Furthermore, we show that HCTZ modulates Ca(2+) uptake by intestinal cells, while affecting the electrical parameters of the cellular membrane, thus suggesting a functional interaction between NCC and the epithelial voltage-dependent calcium channel. The experiments presented here support the hypothesis of a direct involvement of the intestinal cells in the interaction between HCTZ and NaCl, as well as calcium homeostasis.

Animals↗
PubMed1989

The interaction between plant lectins and the small intestinal epithelium: a primary cause of intestinal disturbance.

The literature concerning the effects of plant lectins on the small intestinal epithelium is reviewed. It appears that after oral intake, intact plant lectins can reach the small intestinal lumen. Their binding to the mucosal surface evokes an increased synthesis of glycoproteins and a degeneration of the intestinal epithelium. The epithelial alterations may result in hyperregenerative villus atrophy and endogenous nitrogen loss. These changes ultimately can lead to less efficient feed conversion, diminished growth, scouring, wasting and death. The possible significance of plant lectins in digestive disturbances in farm animals is suggested.

Animals↗