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At least 1,063 records · Page 59Linked to original sources
PubMed1999

Epidermal growth factor receptor (EGF-R) localization in the apical membrane of the enterocytes of rat duodenum.

The maintenance of gastrointestinal epithelium integrity requires a fine balance between proliferation and differentiation as well as protection against gastric acid secretion. Some growth factors, such as epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha), bind to epidermal growth factor receptor (EGF-R) to exert these functions. The exact location of EGF-R within the duodenal area is controversial and still not completely known. Immunohistochemical and Western blot techniques using a monoclonal anti-EGF-R antibody were performed on the adult rat duodenum. The duodenal enterocytes expressed EGF-R in the apical membrane and in the supranuclear area along the length of the villuos. The Lieberkhüm crypts and Brunner's glands also showed a positive immunostaining. By Western blot analysis we identified in the duodenal scrape a band with an apparent molecular weight of 175 kDa. Our results suggest a functional role for the luminal EGF and/or TGF-alpha in the establishment and maintenance of the epithelial renewal, probably by stimulation of cell proliferation, differentiation and migration.

Animals↗
PubMed1993

Reperfusion of duodenum and pancreas following 24 hr of cold storage in Perfadex or UW solution.

We have studied the immediate reperfusion and the graft outcome of the duodenum and pancreas separately in a porcine whole-organ pancreaticoduodenal allograft transplantation model using 24 hr of cold storage. Of 19 transplantations, 12 grafts were perfused and stored in Perfadex and 7 in University of Wisconsin (UW) solution. The organ weights before and after storage were determined in 6 grafts stored in Perfadex and 6 grafts stored in UW solution in order to quantify the degree of dehydration of the graft during storage. In 6 of the grafts perfused with Perfadex, a hyperosmotic salt dextran-containing solution (HSD) was perfused into the graft aorta at reperfusion. Duodenal reperfusion and reperfusion injury were studied by measuring mucosal pH (pHi) and by microscopic examination, respectively. Pancreatic reperfusion was studied by scoring the macroscopic appearance and microscopic examination. Daily blood glucose was used to determine the endocrine function and a secretin-cholecystokinin stimulation test was performed on the second postoperative day to evaluate the exocrine function. All duodenal grafts except 1 in the UW group showed a sufficient reperfusion according to pHi and all had microscopic changes suggesting a moderate reperfusion injury. The macroscopic appearance of pancreas was significantly worse in the UW group than in the two Perfadex groups. Only 1 of 7 grafts in the UW group showed signs of endocrine function on the first postoperative day compared with 11 of 12 in the Perfadex groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1998

Involvement of PACAP in acid-induced HCO3- response in rat duodenums.

Pituitary adenylate cyclase activating polypeptides (PACAP) stimulate duodenal HCO3- secretion in the rat. The present study was performed to determine whether endogenous PACAP is involved in the mechanism of acid-induced HCO3- response in the duodenum, using a PACAP antagonist, PACAP6-27. Under urethane anaesthetised conditions, a duodenal loop that was made between the pylorus and the area just above the outlet of the common bile duct was perfused with saline, and the HCO3- secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Duodenal HCO3- secretion was significantly stimulated by i.v. administration of PACAP-27 (8 nmol kg-1) as well as vasoactive intestinal polypeptide (VIP: 8 nmol kg-1). The effect of PACAP-27 (8 nmol kg-1) was equivalent to that induced by prostaglandin E2 (300 micrograms kg-1, i.v.) and significantly suppressed by either PACAP6-27 (40 nmol kg-1, i.v.) or VIP antagonist (Ac-Tyr1, D-Phe2-VIP: 40 nmol kg-1, i.v.). These peptide antagonists suppressed duodenal HCO3- secretory response to VIP but did not have any effect on either basal or PGE2-stimulated HCO3- secretion. On the other hand, the duodenal mucosa responded to acidification by increasing HCO3- secretion in a indomethacin-sensitive manner, and this process was also significantly suppressed by both PACAP6-27 and VIP-antagonist. Duodenal damage induced by acid perfusion (100 mM HCl for 4 h) was significantly worsened by PACAP6-27, VIP antagonist as well as indomethacin at the doses that suppressed acid-induced HCO3- secretion. These findings suggest that PACAP may play a role in local modulation of the duodenal mucosal integrity, by mediating the HCO3- secretory response induced by mucosal acidification.

Anesthesia↗
PubMed1996

Relationship between nitric oxide and platelet-activating factor in castor-oil induced mucosal injury in the rat duodenum.

The modulation of platelet activating factor (PAF) formation in duodenal tissue by nitric oxide (NO) released in response to castor oil was studied in rats pretreated with NG-nitro-L-arginine methyl ester (L-NAME, 6.25-25 mg/kg, i.p.), an inhibitor of NO synthase, NG-nitro-D-arginine methyl ester (D-NAME, 25 mg/kg, i.p.), the inactive enantiomer of L-NAME or isosorbide-5-mononitrate (IMN, 30-90 mg/kg, p.o.), a NO donating compound. Castor oil (2 ml/rat orally) increased PAF production in the rat duodenum 3 h after challenge. L-NAME, but not D-NAME, enhanced the amount of PAF formed by duodenal tissue, while IMN (30-90 mg/kg) counteracted the effects of L-NAME (12.5 mg/kg) and also reduced PAF release in the tissue of rats treated with castor oil. L-NAME 12.5 mg/kg, but not D-NAME, enhanced both macroscopic damage and acid phosphatase release induced by castor oil. These effects were reduced by a PAF antagonist BN 52021 (3-t-Butyl-hexahydro-4, 7b, 11-trihydroxy-8-methyl-9H-1, 7a-epoxymethano-1H, 6aH-cyclopenta [c] furo [2, 3b] furo [3'2':3,4] cyclopenta [1.2-d]furan-5,9,12(4H)trione) 10 and 20 mg/kg i.p. Such findings suggest that endogenous nitric oxide could reduce PAF biosynthesis in castor oil-treated rats.

Acid Phosphatase↗
PubMed1989

The role of intracellular calcium stores in motilin induced contractions of the longitudinal muscle of the rabbit duodenum.

The contraction of longitudinal muscle strips of the rabbit duodenum in response to motilin and acetylcholine was investigated in normal and high K+-solutions in the presence and absence of external calcium, in order to demonstrate the existence of pharmaco-mechanical coupling for motilin and to examine whether the peptide mobilizes calcium from an intracellular store. In depolarized smooth muscle (140 mM K+), motilin (3.2 x 10(-9)-1 x 10(-7) M) and acetylcholine (1 x 10(-5) M) were still capable of causing a considerable, transient, concentration-dependent contraction in the presence of Ca2+. The 'extra'-contraction to motilin was not blocked by tetrodotoxin (1 microgram/ml) nor by atropine (10(-7) M), but acetylcholine (10(-5) M) was blocked by atropine. Verapamil (10(-7) M) could selectively block the K+ contraction without affecting the extra agonist contraction. Nitroprusside was ineffective up to 10(-4) M in high K+-solutions, but in normal Hepes-buffer it caused a concentration-dependent rightward shift of the concentration-response curve of motilin and acetylcholine contractions. In a calcium-depleted medium, high K+-depolarized muscle strips were still responsive to motilin and acetylcholine, but higher concentrations (10(-6) M) were needed than in the presence of calcium and the contractions reached only 57 +/- 11% and 74 +/- 9% respectively of the maximal contraction in 1.2 mM Ca2+ containing solutions. The response to motilin (10(-6) M) was not only smaller than that to acetylcholine (10(-5) M), it also faded more rapidly with time.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMedDate not supplied

Periduodenal panniculitis due to spontaneous rupture of a pancreatic pseudocyst into the duodenum.

We report a patient with transient periduodenal panniculitis due to spontaneous rupture of a pancreatic pseudocyst into the duodenum. He developed sudden onset of severe epigastric and back pain with jaundice, mimicking the symptoms of acute pancreatitis. However, the serum and urinary amylase levels did not increase. CT scans showed disappearance of his pseudocyst and periduodenal panniculitis without any evidence of acute pancreatitis. The CT findings of periduodenal panniculitis and his symptoms both improved within 3 weeks. A duodenal fistula leading to the remnant pseudocyst and narrowing of the periduodenal portion of the common bile duct were demonstrated by endoscopic retrograde cholangiopancreatography.

Aged↗
PubMed1985

Ultrastructure of enterochromaffin cells and associated neural and vascular elements in the mouse duodenum.

Enterochromaffin cells of adult mouse duodenum were studied with light- and electron-microscopical techniques. They were distinguished from other enteroendocrine cells by their pleomorphic, electron-dense secretory granules in the basal cytoplasm. At the apices of enterochromaffin cells, tufts of short microvilli bordered the gut lumen. At their bases, irregular cytoplasmic extensions were either in contact with or passed through the basal lamina. The presence of cytoplasmic extensions in close proximity to fenestrated capillaries and subepithelial nerves suggested an endocrine or paracrine function. Electron micrographs of serial thin sections were used to reconstruct an enterochromaffin cell from the crypt epithelium in three dimensions and to determine its relationship with the underlying neural plexus. Although extensions from the serially sectioned and reconstructed cell and other enterochromaffin cells studied in crypt epithelia protruded through the basal lamina, no synaptic contacts were seen. Evidence of a synaptic contact between a neurite and another type of enteroendocrine cell (possibly an intestinal A cell), suggested a neurocrine role for some of the basally-granulated cells. Possible functions of enterochromaffin cells are discussed in the light of recent literature on the system of enteroendocrine cells, also known as APUD (amine precursor uptake and decarboxylation) cells and/or paraneurons.

Animals↗
PubMed1984

Cellular and subcellular distribution of iron in the lamina propria of rat duodenum.

Cellular and subcellular distribution of iron in the lamina propria of rat duodenum was studied after a single i.p. injection of iron dextran, using electron microscopy and peroxidase cytochemistry. X-ray spectrum microanalysis was used for positive identification of iron. Iron-containing particles (IP) were found in the cytoplasm of three cell types, viz. macrophages, pericytic reticular cells and sheathing fibrocytes. IP-containing organelles in lamina propria cells were more heterogeneous compared to absorptive cells and, in addition, some differences were noted in the subcellular distribution of IP in the 3 cell types. A common denominator in these 3 cell types was the presence of endogenous peroxidase, also shared by Kupffer cells which are known to be involved in iron storage. Peroxidase activity was absent in absorptive epithelial cells. It is hypothesized that the cells of the lamina propria, like Kupffer cells, may be the site of storage of excess iron absorbed, releasing iron upon demand and migrating into the lumen to prevent iron overload. In this fashion they may regulate the exchange of iron with the environment. The presence of peroxidase in these as well as Kupffer cells, and its absence in absorptive cells also raises the possibility that this enzyme may be related to certain aspects of iron storing process.

Animals↗
PubMed1979

Immunocytochemical localization of a calcium-binding protein in the rat duodenum.

The cellular localization of the vitamin D-dependent calcium-binding protein (CaBP) in the duodenum of rat was studied using indirect immunofluorescence and immunoperoxidase-staining methods. Specific positive reaction product, indicative of the presence of CaBP, was exclusively located within the villous part of the duodenal mucosa. Moreover, CaBP was detected mainly within the supranuclear region of the cytoplasm of absorptive cells and also at the level of their basal laminae. CaBP was not demonstrable either in the nuclei or associated with the brush border membrane of absorptive cells. Also, CaBP was neither detectable in goblet cells nor in sub-epithelial layers. When the specific anti-CaBP antiserum was replaced by nonimmune rabbit serum or when it was preabsorbed on a CaBP-Sepharose conjugate, no positive immunostaining was seen. Together with recent biochemical data our observations agree well with the view that CaBP may act as an intracellular "buffer" by protecting the cell against too high Ca2+ concentrations.

Animals↗
PubMed1981

The effect of polymyxin B and some mast-cell constituents on mucosal mast cells in the duodenum of the rat.

Mucosal mast cells in the rat duodenum show no morphological signs of exocytosis of granules and do not release histamine after treatment with polymyxin B in doses large enough to cause almost complete degranulation of connective-tissue mast cells of tongue, skin, and mesentery with concomitant release of approximately 60% of the tissue histamine. Administration of polymyxin B in gradually increasing doses over a period of 5 ds resulted in a statistically significant increase in mucosal mast cells and a comparable increase in duodenal histamine content, whereas the connective-tissue mast cells in the other tissues examined became fewer in number, the remaining cells showing profound morphological changes, and tissue histamine levels, were reduced to approximately 40% of the controls. A similar increase in mucosal mast cells has been observed after treatment with another mast-cell secretagogue, compound 48/80. This suggests that the increase in mucosal mast cells may be an indirect effect of these compounds, related to their activation of other mast cells and mediated by material(s) secreted by the connective-tissue mast cells. Possible mediators such as heparin, histamine, and 5-hydroxytryptamine injected for 5 ds in doses large enough to account for the amount released from the degranulated mast cells had no effect on the morphology or numbers of mast cells in any of the tissues examined.

Animals↗
PubMed1991

Serotonin-containing epithelial cells in rat duodenum. II. Quantitative study of the effect of 5HTP administration.

The effect of 5-hydroxytryptophan (5HTP) administration on serotonin (5HT)-containing epithelial cells in rat duodenum was investigated quantitatively using three-dimensional morphometry to determine cell density and HPLC to measure 5HT and 5HTP concentrations. The results are interpreted in terms of the amine precursor uptake and decarboxylation (APUD) capacity of the cells. After administration of 5HTP, no significant change was observed in the density of 5HT-fluorescent epithelial cells in the duodenal region examined. Moreover, no evidence could be obtained that the concentration of 5HT in duodenal villi was increased after 5HTP administration, despite a highly significant increase in serum 5HTP and 5HT levels. These results indicate that no cells in the duodenal epithelium have the ability to decarboxylate exogenously administered 5HTP and convert it to 5HT under physiological conditions.

5-Hydroxytryptophan↗
PubMed1981

Determination of transferrin-like immunoreactivity in the mucosal homogenate of the duodenum, jejunum, and ileum of normal and iron deficient rats.

1. In intestinal mucosal tissue a transferrin-like immunoreactivity (TLIR) was determined after loading with 59Fe-(FeCl3) in vivo. The scraped-off mucosal tissue was homogenized and centrifuged at 100 000 X g. The supernatant was fractionated chromatographically. The TLIR was determined by the Mancini-test. 2. Extrapolated to infinite dilutions of the homogenate the following contents of the TLIR were calculated per cm of the intestinal segment: 28, 20, and 13, microgram/cm in the duodenum, jejunum, and ileum of iron-deficient animals and 15, 14, and 12 microgram/cm in the corresponding intestinal segments of normal rats, respectively. 3. The content of TLIR was compared with the iron uptake of the mucosal tissue from the intestinal lumen during absorption. An "iron turnover number" of 1.6 +/- 0.2 iron atoms per min during the absorption in duodenal and jejunal segments and of 0.5 +/- 0.1 in ileal segments of either iron-deficient and normal animals was calculated for the mucosal transferrin represented by the TLIR.

Anemia, Hypochromic↗
PubMed1993

Effects of cyclosporin A on the blood flow of the native and transplanted rat pancreas and duodenum.

The aim of the present study was to evaluate the effects of cyclosporin A (CyA) on the blood perfusion of the transplanted pancreas. For this purpose syngeneic pancreaticoduodenal transplantations were performed in Wistar-Furth rats. After nephrectomy the graft was anastomosed using a nonsuturing cuff technique to the left renal vessels. Beginning 7 days after transplantation and then continuing for 2 weeks, CyA (15 mg/kg body weight) or vehicle was given p.o. once daily, 6 days a week. The serum CyA concentrations were greater than 600 ng/ml at all points in time tested. Intraperitoneal glucose tolerance tests were normal in CyA-treated animals after 12 days, but the pancreatic insulin concentration was decreased to the same extent in the native and transplanted pancreas. A microsphere technique was used to measure the blood perfusion of the pancreaticoduodenal graft, the native pancreas and duodenum, and remaining kidney 14 days after starting the CyA treatment. The renal blood flow was markedly decreased by CyA when compared with the control animals. In rats given vehicle alone, pancreatic, islet, and duodenal blood flows were higher in the graft than in the corresponding native organs. However, in rats given CyA, hyperperfusion of the graft was not observed. We conclude that the administration of CyA prevents the transplantation-induced blood flow increase seen in pancreaticoduodenal grafts of vehicle-treated rats. These observations may reflect graft denervation.

Animals↗
PubMed1981

Immunohistochemical localization of vitamin D-dependent calcium-binding protein in duodenum, kidney, uterus and cerebellum of chickens.

Calcium-binding protein (CaBP) has been localized with the immunoperoxidase method using antiserum against purified chick duodenal CaBP. Different preparative procedures were employed to investigate the experimental conditions possibly responsible for the contradictory reports in the literature of the precise cellular localization of CaBP. Freeze substitution, frozen sections followed by fixation and coagulant and non-coagulant fixatives were used with appropriate control sections to demonstrate that the true localization of CaBP in the chick duodenum is in the absorptive cell cytoplasm. The goblet cell localization reported in the literature seems to be a diffusion artifact due to inadequate fixation. CaBP was also localized in several other tissues. In the hen uterus, the tubular glands beneath the surface epithelium showed intense reaction. In the kidney, CaBP was present in the cells of the straight and convoluted segments of distal tubules. The cortex of the chick cerebellum showed the CaBP in Purkinje cells. The entire dendritic trees contained the reaction product. No other neurons in the molecular or the granular layer were stained. In the deep cerebellar nuclei, all neurons were negative and these were outlined by deeply staining axons of the Purkinje cells and their synaptic endings.

Animals↗
PubMed1989

The effect of zinc and magnesium on calcium uptake into the rat duodenum slices.

The experiments were carried out on 80 male Wistar rats, divided into four groups as follows: group 1, treated orally with ZnCl2 at a dose of 10 mg Zn2+/kg for 14 days; group 2, control; group 3, MgCl2-treated at a dose of 5 mg Mg2+/kg; group 4, treated with ZnCl2 plus MgCl2 in the same manner as groups 1 and 3. The influx of calcium into the rat duodenum slices was investigated in vitro by the method of Papworth and Patrick. Over a range of calcium concentrations (0-10 mM) the influx of this element was defined as a sum of a saturable term (active transport) and a linear term dependent on concentration (passive transport). In the zinc-treated rats only the saturable term was affected. The study of this term by Lineweaver-Burk plots showed a decrease of the half-saturation constant, Kt, while the maximal value, Jm, remained unchanged. Moreover, magnesium was shown to interact with zinc at gut level because simultaneous oral administration of Mg2+ and Zn2+ to rats protected them against the inhibition of calcium uptake observed when Zn2+ was given alone.

Analysis of Variance↗
PubMed1991

Relationship between gliadin peptide structure and their effect on the fetal chick duodenum.

The tendency to form a beta-turn in alpha-gliadin was estimated using the B-cell determinant prediction program based on the Chou and Fasman probability of beta-turn formation. Six sequences possessing a high probability of beta-turn formation were found. A statistically high agreement was found between these six sequences and three areas in alpha-gliadin with the occurrence of Pro-Ser-Gln-Gln sequence which has recently been considered responsible for toxicity in coeliac disease. By means of solid-phase synthesis seven peptides were obtained covering the above-mentioned regions. Their toxicity was tested using the fetal chick duodenum. The results support the suggestion that peptides containing the sequences Pro-Ser-Gln-Gln and Gln-Gln-Gln-Pro may be involved in the pathogenesis of coeliac disease.

Amino Acid Sequence↗
PubMed1993

Neuropeptides in pig sphincter of Oddi, bile duct, gallbladder, and duodenum.

To better understand the complex structure and function of the sphincter of Oddi (SO), the occurrence and localization of nine neuropeptides, including vasoactive intestinal polypeptide (VIP), bombesin, neuropeptide Y, peptide histidine-isoleucine (PHI), calcitonin gene-related peptide (CGRP), galanin, substance P, serotonin, and somatostatin, were studied by immunohistochemical methods in the pig SO. The SO innervation was compared to gallbladder, common bile duct, and duodenal innervation. Specimens from the SO, gallbladder, common bile duct, and duodenum demonstrated a rich network of nerves, as suggested by light microscopy and confirmed by a myelin marker S-100. SO demonstrated very strong immunoreactivity for VIP, strong immunoreactivity for neuropeptide Y and galanin, moderate immunoreactivity for PHI and CGRP, and borderline immunoreactivity for bombesin and substance P. Serotonin and somatostatin immunoreactivity was also observed, not in the nerves, but in some of the epithelial cells. The gallbladder innervation was virtually identical to the SO innervation, whereas common bile duct and duodenal innervation were slightly different. To our knowledge this is the first time that galanin- and PHI-like immunoreactivities have been observed in the SO. Our observations suggest that these peptides, along with VIP, neuropeptide Y, and CGRP, might play a role in the neural control of biliary motility.

Animals↗
PubMed1984

A study of incidence and relationship of intestinal metaplasia of gastric antrum and gastric metaplasia of duodenum in patients with nonulcer dyspepsia.

The incidence and relationship of intestinal metaplasia of the gastric antrum and gastric metaplasia of the first part of the duodenum were studied in endoscopic biopsies from 120 patients with nonulcer dyspepsia. Intestinal metaplasia was present in 29% of antral biopsies and gastric metaplasia in 39% of duodenal biopsies, with 9% of patients having both. Intestinal metaplasia was not related to alcohol consumption, but was significantly higher in patients who smoked 10 cigarettes or more daily. (P less than 0.002). Gastric metaplasia was associated with duodenitis. Its incidence was significantly higher in males (P less than 0.001) and in patients with a history of high/moderate alcohol intake (P less than 0.02); these findings are reminiscent of the presence of a similar relationship between these factors and duodenal ulcers and support the suggestion that duodenitis and duodenal ulcers probably represent different parts of a single disease spectrum. The presence of both types of metaplasia in 9% of the patients suggest that factors other than gastric acidity may influence the development of metaplasia.

Alcohol Drinking↗