Normal Gastrointestinal Tract Research Articles

Immunohistochemical Localization of CCK1Cholecystokinin Receptors in Normal and Neoplastic Human Tissues

The biological effects of cholecystokinin (CCK) are mediated by two distinct G protein-coupled receptors, CCK1 and CCK2. Although it is well established that CCK receptors are widely distributed throughout the normal gastrointestinal tract, little is known about their cellular and subcellular localization in human normal and neoplastic tissues. We developed and characterized a novel antipeptide antibody to the carboxyl-terminal region of the human CCK1 receptor. Specificity of the antiserum was demonstrated by 1) detection of a broad band migrating at a relative molecular mass of 85,000-95,000 in Western blots of membranes from CCK1-expressing tumors and CCK1-transfected cells, 2) cell surface staining of CCK1-transfected cells, 3) translocation of CCK1 receptor immunostaining after agonist exposure, and 4) abolition of tissue immunostaining by preadsorption of the antibody with its immunizing peptide. The distribution of CCK1 receptors was investigated in 74 human tumors and their tissues of origin. The presence of CCK1 receptors was rarely detected in human tumors except for carcinoids, insulinomas, pituitary adenomas, and meningiomas. CCK1 receptors were clearly located at the plasma membrane and uniformly present on nearly all tumor cells. In the gastrointestinal tract, CCK1 receptor immunoreactivity was highly abundant in chief cells of the gastric mucosa, in myenteric ganglion cells, and in myenteric nerve fibers. This is the first localization of CCK1 receptors in human formalin-fixed, paraffin-embedded tissues at the cellular level. The overexpression of CCK1 receptors in a subset of human neuroendocrine tumors may provide a molecular basis for efficient targeting of these tumors with radiolabeled CCK analogs.

Characterization of metaplastic and heterotopic epithelia in the human gastrointestinal tract by the expression pattern of acyl-CoA synthetase 5.

Metaplastic and heterotopic epithelia are frequently found in the human intestine. The recently cloned human acyl-CoA synthetase 5 (ACS5) is a key enzyme in providing cytosolic acyl-CoA thioesters. The aim of the study was to identify and to locate the expression of ACS5 in the gastric body and the small intestine with metaplasia or heterotopia by different methods. In the normal gastrointestinal tract, ACS5 was predominantly found in the villus epithelium of the small intestine, but not in the gastric mucosa. Of note, strong expression of ACS5 was also detectable in intestinal metaplasia of the stomach. Inversely, ACS5 expression could neither be detected in heterotopic gastric mucosa of the corpus type nor in gastric, pseudopyloric, or antral metaplasia of the small intestine. In conclusion, our data implicate that ACS5 is a suitable differentiating marker molecule in the gastrointestinal tract.

Differential Expression of COX-1 and COX-2 in the Gastrointestinal Tract of the Rat

The aim of this study was to use immunohistochemistry with morphometry to investigate COX-1 and COX-2 expression in the normal rat gastrointestinal (GI) tract and examine if sites of ulceration previously observed with long-term COX-2 inhibitor administration in mice correlate with differential COX-1/COX-2 expression. COX-2 positive cells were observed predominantly in the apical lamina propria of intestinal villi with fewer cells in the mucosal epithelium. The highest level of COX-2 expression was observed at the ileocaecal junction (ICJ). COX-2 expression was also present in parasympathetic ganglia of the submucosa and muscularis. In the stomach, the highest grade of COX-2 expression was observed in the apical lamina propria of the fundus adjacent to the junctional ridge. In contrast, COX-1 positive cells within the lamina propria were evenly distributed along the GI tract but were present in higher numbers than COX-2 positive cells. The mean level of COX-1 expression at the ICJ was not significantly different from the ileum and caecum. Evidence that the highest level of COX-2 expression in normal rats is located on the ileal side of the ICJ provides the first mechanism to explain spontaneous ulceration and perforation of the distal ileum in COX-2 -/- animals.

Gene expression in midgut carcinoid tumors: Potential targets for immunotherapy

Classical midgut carcinoids are serotonin-secreting tumors derived from enterochromaffin cells in the gut. Metastatic disease represents a therapeutic challenge and immunotherapy implies a novel approach for treatment. In order to define antigens suitable for T-cell therapy with a preferential expression in midgut carcinoid tissue a broad screening of genes with preferential neuroendocrine restriction, genes described as over-expressed in various malignancies, and genes encoding cancer-testis associated antigens was performed. The expression of 32 genes was analyzed by reverse transcription polymerase chain reaction (RT-PCR) in 28 midgut carcinoid specimens, in the cell line BON and in normal tissues. Immunohistochemistry (IHC) was used to evaluate protein expression. Expression is shown of genes that have previously not been observed in midgut carcinoid tumors, such as Survivin and GAGEs. Also the expression is confirmed of genes that encode pivotal proteins in enterochromaffin cells, such as TPH1 and VMAT1, and their tissue-restricted expression is indicated. In addition, gene expression of IA-2 and CDX-2 in normal gastrointestinal (GI) tract and in tumor is shown. Protein expression of TPH, VMAT1, and Survivin was detected in tumor tissue. This study elucidates that TPH1, VMAT1, and Survivin should be further investigated as potential target antigens for T cell-mediated immunotherapy of midgut carcinoids.

Surgical complications of cocaine body-packing: a survey of Jamaican hospitals

Body-packing is a common method of smuggling cocaine. Complications requiring surgery do not occur with sufficient frequency to allow any individual surgeon to determine patterns of presentation and the best approach to the conduct of surgery. A survey of all surgical units in Jamaica was conducted. A case was any patient requiring surgery for cocaine body-packing since and including the first reported case in 1987. Seventeen cases were identified. There were 11 cases of bowel obstruction, two of delayed passage of pellets, three of ruptured pellets with cocaine toxicity and one patient panicked and requested surgery. The distal ileum was the commonest site of obstruction in the normal gastrointestinal tract. In all three cases with cocaine poisoning, the ruptured packets were encountered in the upper gastrointestinal tract and several other partially ruptured packets were also found, implying that poor packaging was the cause of rupture. Obstructing packets should be removed but non-obstructing, unruptured packets encountered in the colon may safely be allowed to pass spontaneously. All cases of packet rupture with cocaine toxicity should have immediate surgery.

Carbonic anhydrases in normal gastrointestinal tract and gastrointestinal tumours

Carbonic anhydrases (CAs) catalyse the hydration of CO2 to bicarbonate at physiological pH. This chemical interconversion is crucial since HCO3- is the substrate for several biosynthetic reactions. This review is focused on the distribution and role of CA isoenzymes in both normal and pathological gastrointestinal (GI) tract tissues. It has been known for many years that CAs are widely present in the GI tract and play important roles in several physiological functions such as production of saliva, gastric acid, bile, and pancreatic juice as well as in absorption of salt and water in intestine. New information suggests that these enzymes participate in several processes that were not envisioned earlier. Especially, the recent reports on plasma membrane-bound isoenzymes IX and XII have raised considerable interest since they were reported to participate in cancer invasion and spread. They are induced by tumour hypoxia and may also play a role in von Hippel-Lindau (VHL)-mediated carcinogenesis.

Histiocytic Subpopulations in the Gastrointestinal Tract

The distribution of specific histiocyte subsets within the human gastrointestinal tract has not been extensively characterized. Our goal was to immunohistochemically evaluate the distribution and location of CD1a-positive, CD68-positive, and Factor XIIIa (FXIIIa)-positive histiocyte subsets within the normal gastrointestinal tract and attempt to relate distribution to possible function. Twenty-nine samples of normal esophagus, stomach, small bowel, large bowel, and anus were routinely processed and immunohistochemically stained with antibodies to CD68, CD1a, and FXIIIa. The distribution and histologic location of histiocyte subsets were qualitatively analyzed. CD1a-positive cells were seen exclusively within anal and esophageal squamous mucosa. CD68 positive histiocytes were present in lamina propria and submucosa throughout the gastrointestinal tract and in Peyer patches. FXIIIa-positive histiocytes were also abundant in lamina propria and submucosa throughout the gastrointestinal tract, particularly around pericryptal sheaths and in parafollicular regions surrounding Peyer patches. Our results showed that there are distinct subpopulations of gastrointestinal histiocytes, and that distribution varies according to both cell type and site. Because Langerhans cells are epidermal antigen processing/presentation cells, their exclusive presence in squamous mucosa suggests an analogous function there. The prominence of both CD68 and FXIIIa-positive cells surrounding glandular pericryptal sheaths suggests that they are important to immune function at this mucosal interface and may play a role in communication between glands and lamina propria. In addition, the presence of specific histiocyte subsets within Peyer patches and para-follicular regions suggests that they are involved in different aspects of antigen processing associated with gut lymphoid tissue. Further studies are needed to explore the relation between specific histiocyte subsets and gastrointestinal disease processes.

Expression of a colorectal antigen defined by a new monoclonal antibody, CO-TL1

A murine monoclonal antibody (MoAb CO-TL1, IgG1) has been raised by differential screening of hybridoma supernatants on sections of human large and small intestines, followed by screening on colon adenomas as well as on colorectal carcinomas. In both paraffin sections and cryostat sections, the antibody stained strongly all cell types in adult, neonatal and fetal human colorectal epithelium, that is, the goblet cells, the columnar cells and the endocrine cells. No staining was observed in the remaining parts of the normal gastrointestinal tract and other tissues. As revealed by immuno electron microscopy the epitope was present in the apical and basolateral cell membranes, the Golgi complex, secretory vesicles of goblet and columnar cells, and also in granules of the endocrine cells. The epitope in colorectal tissue sections was resistant to the deglycosylation enzymes neuramidase, diastase and hyaluronidase indicating its proteinaceous nature. This colorectal antigen remained expressed in 100% of colorectal adenomas (n=39) and 86% (n=29) of colorectal carcinomas. The expression was reduced in undifferentiated carcinomas. The CO-TL1 antibody detected also most other gastrointestinal adenocarcinomas and a few carcinomas of the ovary, uterus, breast, gallbladder and pancreas. However, it never detected carcinomas derived from the thyroid, lung, liver, bladder, kidney, prostate, testis, serous membranes of body cavities and skin. A wild-type variant protein of >300 kDa of the colorectal antigen was identified in normal colorectal epithelium. In colorectal tumours, however, two tumour variant forms were found of 160–200 and 115–140 kDa, respectively. Our data indicate that this new MoAb CO-TL1 can be considered as a useful marker, which identifies normal colorectal epithelium and gastrointestinal tumours and especially colorectal tumours with high accuracy and excludes tumours originated from thyroid, lung, liver, bladder, kidney, prostate, testis, mesothelium and skin.

Interactions between lipopolysaccharide and the intestinal epithelium.

I ischemia often results in endotoxemia, and endotoxemia significantly increases postoperative morbidity and mortality rates in patients with ischemic intestinal disease. Even if all grossly ischemic intestine is resected, remaining intestine may be injured as a result of distention. In addition, intestine at the margins of the resection may have evidence of serosal injury and neutrophil infiltration. Endotoxemia is a result of absorption of lipopolysaccharide (LPS) from intestinal gram-negative bacteria. Gram-negative bacteria release LPS during periods of rapid proliferation and cell death. Once absorbed, LPS stimulates host cells, principally monocytes and macrophages, to produce and release endogenous mediators of inflammation, triggering pathophysiologic effects that range from mild fever to fatal septic shock. Although intestinal epithelial cells were once regarded as merely a barrier to LPS, it has recently been determined that these cells interact specifically with LPS molecules. Intestinal epithelial cells are normally exposed to high numbers of intact bacteria and high concentrations of bacterial products and form a barrier to LPS absorption and intestinal microbial invasion. As a result, intestinal epithelial cells must recognize and react to pathologic bacteria but avoid responding to the normal gastrointestinal tract flora. Inappropriate responses to normal gastrointestinal tract flora likely play a role in the development of inflammatory bowel disease. Intestinal epithelial cells are regularly exposed to LPS, and small amounts of LPS may be found in the portal blood of healthy individuals. Kupffer cells in the liver typically remove this LPS before it can reach the systemic circulation. However, if the amount of LPS in the portal blood overwhelms the liver’s mechanisms for LPS removal, then LPS will enter the systemic circulation. Circulating LPS interacts with host cells via specific cell surface receptors, and the intercalation of these molecules is considered to be an important step in the activation cascade.

The gastrointestinal stem cell.

The longevity of adult stem cells, and their potential for vast tissue regeneration, makes them a focal point of current research and debate, with future aspirations for the use of stem cells in the treatment of a number of human pathological conditions. Due to the rapid rate of cell turnover in the gastrointestinal tract, the stem cells of this tissue are amongst the most assiduous in the body, although they remain unidentified to this day due to their immature, undifferentiated phenotype. However, our knowledge of the mechanisms regulating gastrointestinal stem cell function is evolving, with the identification of putative cellular markers and the elucidation of signalling pathways which regulate cell behaviour in the normal and neoplastic gastrointestinal tract. This review describes the fundamental properties of the gastrointestinal stem cell including: (i) their number, location and origins, (ii) their primary function of deriving gastrointestinal cell lineages and maintaining tissue homeostasis, (iii) the acquisition of gastrointestinal cell lineages from adult stem cells of extraneous tissues and the consequences of this in a therapeutic context, and (iv) the genetic and morphological phenomena surrounding neoplastic transformation in the gastrointestinal tract.

WNT2 and human gastrointestinal cancer (Review)

WNT2 gene on human chromosome 7q31 is a paralog of the WNT2B gene on human chromosome 1p13. Rat Wnt2 gene was identified within rat genome draft sequence AC095247.4. Human WNT2 showed 96.4% total-amino-acid identity with rat Wnt2, 96.1% with mouse Wnt2, 68.6% with zebrafish wnt2, and 67.8% with fugu wnt2. WNT2 is an evolutionarily conserved secreted-type glycoprotein belonging to the WNT family. WNT2 mRNA is expressed in human fetal lung and placenta, but almost undetectable in normal gastrointestinal tract. WNT2 mRNA is frequently up-regulated in human gastric cancer due to tumor-stromal interaction, and WNT2 gene is rarely amplified in human gastric cancer. WNT2 mRNA is also frequently up-regulated in colorectal polyps, primary colorectal cancer of stage A-C, and also in liver metastasis from colorectal cancer. Putative biding sites for estrogen receptor, GATA-1, AP-2, TCF-1, BHLH, MBF-I, p53, and HNF-5 are located within the 5'-flanking region of human WNT2 gene. WNT2 is up-regulated by beta-estradiol in human MCF-7 cells; however, the mechanism of WNT2 up-regulation in most cases of gastrointestinal cancer remains to be elucidated. WNT2 is a tumor marker of gastric and colorectal cancer. Detection of theWNT2 protein in feces by immunohistochemistry or ELISA and WNT2 mRNA in feces by cDNA-PCR or custom-made microarray could be applied for screening of colorectal cancer. Because WNT2 up-regulation leads to carcinogenesis through activation of the WNT-beta-catenin pathway, WNT2 specific antagonist might be applied for chemoprevention or treatment of gastrointestinal cancer. WNT2 gene is one of the targets for pharmacogenomics in the field of oncology.

Radiographic gastrointestinal contrast study in the ostrich (Struthio camelus).

Ten gastrointestinal contrast studies were performed with barium on seven clinically healthy ostriches. Concentrations of 25-100% w/vol liquid barium sulfate at 7 and 10 ml/kg were administered by stomach tube after withholding food for 16 h. A 6-frame technique for left-to-right lateral views in standing and a 3-frame technique for the dorsoventral views in sternally recumbent adult ostriches were used for survey and contrast radiographs. Objectives were to describe the appearance of the normal gastrointestinal tract with contrast radiography and to provide a guideline for optimal dosage and concentration of barium sulfate as well as a reliable protocol for frequency of radiographs. Structures that were consistently identified included the esophagus, proventriculus, ventriculus, duodenum, jejunum, proximal, and distal rectum. Due to the superimposition of the remainder of the small intestine, individual components were difficult to differentiate. The caeca were inconsistently highlighted and only for a short time. The ventral pouch of the coprodeum never filled with contrast medium.

EPR spectroscopy and imaging of oxygen: applications to the gastrointestinal tract.

EPR imaging has emerged as an important tool for noninvasive three-dimensional (3D) spatial mapping of free radicals in biological tissues. Spectral-spatial EPR imaging enables mapping of the spectral information at each spatial position, and, from the observed linewidth, the localized tissue oxygenation can be mapped. We report the application of EPR imaging techniques enabling 3D spatial and spectral-spatial EPR imaging of small animals. This instrumentation, along with the use of a biocompatible charcoal oximetry-probe suspension, enabled 3D spatial imaging of the gastrointestinal (GI) tract, along with mapping of oxygenation in living mice. By using this technique, the oxygen tension was mapped at different levels of the GI tract from the stomach to the rectum. The results clearly show the presence of a marked oxygen gradient from the proximal to the distal GI tract, which decreases after respiratory arrest. This technique for in vivo mapping of oxygenation is a promising method, enabling the noninvasive imaging of oxygen within the normal GI tract. This method should be useful in determining the alterations in oxygenation associated with disease.

Cellular localization of cholecystokinin receptors as the molecular basis of the periperal regulation of acid secretion.

Gastrin stimulates gastric acid secretion through direct activation of CCK-B/gastrin receptors on parietal cells and indirectly through release of histamine from ECL cells. Cholecystokinin (CCK) is structurally closely related to gastrin and shares high affinity for CCK-B/gastrin receptors. In contrast to gastrin, CCK also recognizes CCK-A receptors. While CCK appears to be a negative regulator of gastric acid secretion and postprandial release of gastrin in the normal human gastrointestinal tract, its impact on the pathogenesis of acid hypersecretion in Helicobacter pylori-infected individuals remains uncertain. This article will review the endocrine and paracrine regulatory pathways which are activated by CCK/gastrin peptides and which appear relevant in the pathogenesis of peptic ulcer disease in man.

Abdominal vagal afferent neurones: an important target for the treatment of gastrointestinal dysfunction.

Vagal afferents are extensively distributed in the digestive tract from the oesophagus to the colon. They are involved in the reflex control of normal gastrointestinal (GI) tract function (e.g. secretion and motility) as well as reflexes more characteristic of diseases such as functional dyspepsia and gastroesophageal reflux disease (e.g. vomiting, disordered lower esophageal sphincter relaxation and gastric accommodation). They are also implicated in signalling non-painful sensations (e.g. nausea and early satiety) associated with disease. A variety of receptors has been identified on vagal afferents, which can either enhance (e.g. 5-HT3, CCK1, VR1 and NK1 receptors) or reduce (e.g. ghrelin, leptin, k-opioid and GABAB receptors) activity, offering a range of potential therapeutic targets. Commonly used laboratory species (e.g. rat and mouse) lack an emetic reflex, and the implications of this for models of upper GI disorders have been explored in the light of expanding knowledge of the neuropharmacology of the emetic reflex implicating glutamate, prostanoids, cannabinoids and substance P. Additional pathophysiological roles for vagal afferents (e.g. in thermoregulation, arousal and fatigue) are being investigated, raising the intriguing possibility of the vagus as a target in non-GI disorders.

Sonographic investigations of the gastrointestinal tract of granivorous birds.

This article describes the sonographic examination of the normal gastrointestinal tract of granivorous birds. Preliminary tests with dead birds were performed to get an idea of the sonographic echotexture of the avian gastrointestinal tract. Later, clinically healthy seedeaters of different weights were examined sonographically. As equipment a convex microcurved scanner with a particularly small coupling surface and an adjustable frequency from 5.5-7.5 MHz was used. For the investigation of the gastrointestinal tract, six sonographic approaches are described. After a starving time of 18 hours in the granivorous birds and water input, the best sonographic image quality could be obtained. Using this method, the crop, ventriculus, intestines, and cloaca could be demonstrated sonographically; whereas, it was not possible to visualize the normal proventriculus in granivorous birds. In contrast to mammals, the different layers of the wall of the gastrointestinal tract could not be visualized with the equipment used. Motility of individual parts of the gastrointestinal tract (GI tract), however, could be well demonstrated.

Essentials of nutrition in dogs and cats with gastrointestinal disease

NUTRITION plays a key role in the management of gastrointestinal disease in dogs and cats, and it is possible to manage some cases by dietary therapy alone. Dietary components can...

Estrogen receptor beta is expressed in human stomach adenocarcinoma.

In stomach adenocarcinoma, the role of the hormonal receptor, estrogen receptor (ER), has been controversial. Recently, a new estrogen receptor, called estrogen receptor beta (ER beta), was found to be expressed in various tissues including normal gastrointestinal tract. In this paper, the expression of ER beta in stomach adenocarcinomas has been investigated for the first time, specifically in signet ring cell adenocarcinomas, together with surrounding non-cancerous tissues. By immunohistochemistry the expression of ER alpha and beta was studied in 29 stomach adenocarcinomas, ten signet ring cell adenocarcinomas, and 19 other adenocarcinomas. Western blotting was performed to examine the immunohistochemical result. Statistical studies (Student's t test and chi(2)-test) explored the relation between the immunohistochemical result and clinicopathological characteristics. All 29 adenocarcinomas, including the signet ring cell ones, demonstrated clear ER beta nucleus staining. Lymphocytes, venous endothelial cells, smooth muscle, and non-cancerous stomach glands also showed strong ER beta staining, while no staining was observed in the immunohistochemistry of ER alpha. Western blotting showed equivalent ER beta protein levels in cancerous and non-cancerous tissues, which was consistent with the results of immunohistochemical staining. Among signet ring cell adenocarcinomas of the stomach, cytoplasm were stained in addition to nuclei, specifically in patients under the age of 40 years. Our results imply that the effects of estrogen in stomach cancer, as well as those in normal stomach, may be mediated by ER beta, and that the role of ER beta may differ by the subtype of stomach adenocarcinoma - specifically signet ring cell adenocarcinomas and other ones - although large scale samples are needed to confirm these findings.

Molecular cloning and characterization of human SOX17

SOX proteins are a family of transcription factors with high-mobility-group DNA-binding domain (HMG box) homologous to SRY, which are implicated in embryogenesis. Xenopus Sox17 alpha, Sox17 beta, and Sox3 are reported to negatively modulate the WNT - beta-catenin - TCF signaling pathway. Here, human SOX17 gene fragments were identified in human genome draft sequences by using bioinformatics, and SOX17 cDNAs were isolated by using cDNA-PCR. Human SOX17 was found to encode a 414-amino-acid protein with a HMG box, which was homologous to SOX18 and SOX7. SOX17 gene, consisting of 2 exons, was located in human chromosome 8q12-q13 region. SOX17 mRNAs of 2.5- and 2.2-kb in size were detected in adult heart, lung, spleen, testis, ovary, placenta, fetal lung, and kidney. In normal gastrointestinal tract, SOX17 mRNA was preferentially expressed in esophagus, stomach and small intestine than in colon and rectum. SOX17 mRNA was almost undetectable in human cancer cell lines HL-60, HeLa S3, K-562, MOLT-4, Raji, SW480, A549, G-361, and also in 66 cases of human primary tumors derived from various tissues, except one case of primary cervical cancer. This is the first report on molecular cloning and characterization of human SOX17.

Apolipoprotein E and colon cancer: Expression in normal and malignant human intestine and effect on cultured human colonic adenocarcinoma cells

Background: Apolipoprotein E (apo E) is a key regulatory protein in lipoprotein metabolism and it is also a potent inhibitor of cell proliferation. Although genetic alterations of apo E affect enterohepatic cholesterol transport and, presumably, the risk of colon carcinoma, the expression and potential functions of apo E in the human intestine are poorly known. Methods: The localization of apo E in normal and malignant gastrointestinal tract was studied using immunohistochemistry and in situ hybridization. The effect of apo E3 on cell polarity and the distribution of β-catenin was examined in HT29 human colon adenocarcinoma cell lines. Results: Both apo E protein and mRNA were present throughout human intestine. The macrophages in the superficial lamina propria of normal colon were more strongly positive for apo E than those in the small intestine, where the most positively stained cells were dendritic cells and macrophages in the germinal centers of lymphoid follicles. In carcinomas, intensely positive macrophages surrounded the tumor area. In cultured undifferentiated HT29 cells, treatment with apo E improved cell polarity and translocated β-catenin from the cytoplasm to cell–cell adhesion sites. Conclusions: Mononuclear phagocytes and endocrine cells are the main source of apo E in the gastrointestinal tract. We hypothesize that macrophage-derived apo E may modulate epithelial integrity and thus contribute to cell growth.