SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The effect of intraarterial glucagon injection on the glycogen content of the intestinal mucosa of the dog and the rat has been investigated. In both species significant glucagon-induced reduction of mucosal glycogen contents was revealed.
BACKGROUND/AIMS: Vascular endothelial growth factor (VEGF) is a heparin-binding glycoprotein with potent angiogenic, mitogenic and vascular permeability-enhancing activities specific for endothelial cells. Recent studies have shown significantly increased VEGF serum levels in patients with active Crohn's disease and ulcerative colitis. The origin of the circulating VEGF is not yet completely described. The present investigation examines the VEGF production of colonic mucosa in consideration of mucosal disease activity in patients with inflammatory bowel disease. METHODOLOGY: Fifteen patients with inflammatory bowel disease were studied, 9 patients with Crohn's disease and 6 patients with ulcerative colitis. Biopsies were taken from endoscopically inflamed and non-inflamed colonic mucosa. Therefore, an analysis of the spontaneous VEGF production of cultured biopsies without stimulus and of the histological grade of inflammation scored on a scale of 0-3 (normal mucosa--severe chronic colitis) were performed. Eight patients with irritable bowel syndrome served as controls. VEGF levels in the supernatant of cultured mucosal biopsies were measured using an enzyme linked immunosorbent assay. RESULTS: VEGF production is expressed as pg/mg wet weight of the biopsies. Inflamed mucosa of patients with active ulcerative colitis (16.27 +/- 10.39, p = 0.003, n = 6) and active Crohn's disease (9.88 +/- 5.98, p < 0.012, n = 9) showed a significantly higher spontaneous production of VEGF by colonic mucosa than normal mucosa of controls (3.16 +/- 1.63, n = 8). In addition, there was an increased unstimulated VEGF production by cultured inflamed mucosa of patients with Crohn's disease compared with non-inflamed mucosa (3.88 +/- 3.66, p < 0.015, n = 9). In both Crohn's disease and ulcerative colitis, there was no significant difference between VEGF production by non-inflamed mucosa and normal mucosa of controls. CONCLUSIONS: The present study identifies the intestinal mucosa as one of the origins of the elevated VEGF serum levels in patients with active inflammatory bowel disease and verifies the findings of recent studies about the importance of VEGF in Crohn's disease and ulcerative colitis.
The numbers and proportions of immunocytes producing IgA, IgM, or IgG were found to be normal in the proximal small intestinal mucosa of patients with IgA nephropathy. There was no indication of any quantitative aberration in the mucosal humoral immune system at this secretory tissue site.
To obtain macrophage-rich cell suspensions from human intestinal mucosa, lamina propria specimens were dissociated by incubating in EDTA-collagenase-DNAase solutions and further purified by counter-current centrifugation. During enzymatic incubation macrophage dissociation was linear over the first 8-10 h, reaching a maximum concentration of 10% of total cells and then it plateaued. Counter-current centrifugation resulted in a 5-fold enrichment of macrophages to a mean of 50% with an average recovery rate of 84%. Yields exceeded 0.69 X 10(5) macrophages/g mucosa. Greater than 90% of these cells phagocytosed Staphylococcus aureus, and could be maintained in culture for up to 8 days. Electron microscopy showed satisfactory preservation of the ultrastructure of the macrophages, which also seemed functionally intact.
Fructooligosaccharides (FOS) reach the large intestine and are fermented into short-chain fatty acids (SCFA), lactate, and carbon dioxide. As the major energy source for the epithelial cells of the large intestine, n-butyrate stimulates the proliferation of cells as well as mineral and water absorption from the lumen. We examined the effect of dietary FOS supplementation on luminal SCFA production and its influence on the morphometrical variables of mucosa of the large intestine in commercially available pigs. Six weaning piglets were used. After 7 d of adaptation, three pigs were given a test diet containing FOS (10%) ad libitum for 10 d. The other three remained on the basal diet and were used as controls. At the end of the experiment, their large intestines were removed, and the cecum, gyri centripetales, gyri centrifugales, and rectum were separated. The contents of each portion were collected and measured for SCFA concentration, pH, and moisture. A micrometer was used to measure the crypt depth. The numbers of epithelial and mitotic cells in the crypt columns were also counted. The concentration of SCFA was significantly higher in piglets fed FOS than in the controls. The concentration of n-butyrate was markedly stimulated by FOS. The number of epithelial. mitotic, and mucin-containing cells was higher in piglets fed FOS than in the controls. Accordingly, the crypt depth was larger in the FOS-fed piglets. The luminal n-butyrate concentration showed a significantly positive correlation with the crypt depth and the number of epithelial, mitotic, and mucin-containing cells.
The regulatory properties of adenylate cyclase in small intestinal mucosa were investigated. Glucagon, epinephrine and isoproterenol failed to activate the cAMP synthesis; prostaglandin E1 caused a 2.8-fold, while cholera toxin-a 4.5-fold stimulation. The latter was not able to increase the rate of glucose synthesis from alanine in vitro, but increased markedly the in vivo incorporation of 14C-labeled alanine into the mucus glucosamine. Unlabeled glucosamine excretion was also enhanced 3-fold. This provides evidence for the involvement of glycolysis and gluconeogenesis enzyme systems in the mucosal glycoprotein synthesis. It was assumed that both metabolic pathways may play a common physiological role, namely, to convert carbohydrates and gluconeogenic precursors into the substrate for glucosamine synthesis which is thought to be a rate-limiting step in small intestinal mucus secretion.
The possibility that the autonomic nervous system may influence the function of intestinal mucosa was investigated by assessing the effect of acetyl choline on ion transport in human intestine. Isolated pieces of stripped ileal mucosa were mounted in Perspex flux-chambers and bathed in isotonic glucose Ringer's solution. Acetyl choline caused a rise in mean potential difference (8.8-12.3 mV, P less than 0.002) and short circuit current (287.7-417.2 muA-cm-2, P less than 0.01) (n = 12), observable at a concentration of 0.01 mM and maximal at 0.1 mM. This effect was enhanced by neostigmine and blocked by atropine. Isotopic flux determinations revealed a change from a small mean net Cl absorption (58) to a net Cl secretion (-4.3mueq-cm-2-h-1P less than 0.001) due predominantly to an increase in the serosal to mucosal unidirectional flux of Cl (10.63-14.35 mueq-cm-2-h-1P less than 0.05) and a smaller reduction in the mucosal to serosal flux (11.22 to 10.02 mueq-cm-2-h-1P less than 0.05). Unidirectional and net Na transport was unaffected. A similar electrical and ion transport response was observed in a single study of two pieces of jejunal mucosa. In the absence of glucose net chloride secretion was produced and again an insignificant effect on net sodium transport was noted. Acetyl choline did not provoke a sustained effect on mucosal cyclic adenine nucleotide levels although a short-lived cyclic adenine nucleotide response was seen in some tissues 20-30 s after drug addition. These studies demonstrate that acetyl choline does influence human intestinal ion transport by stimulating chloride secretion and suggest a possible mechanism by which the parasympathetic nervous system could be concerned in the control of ion transport.
BACKGROUND AND AIMS: Coeliac disease is characterised by atrophy of the villi and hyperplasia of the crypts in the mucosa of the small intestine. It is caused by an environmental trigger, cereal gluten, which induces infiltration of the mucosa by inflammatory cells. We hypothesised that these inflammatory cells express cyclooxygenase 2 (COX-2), an enzyme that contributes to the synthesis of pro and anti-inflammatory prostaglandins and is known to be expressed at sites of inflammation in the stomach and colon. We have investigated expression of COX-2 in the coeliac disease affected small intestinal mucosa where it may be an indicator of either disease induction or mucosal restoration processes. PATIENTS AND METHODS: Small intestinal biopsy samples from 15 coeliac patients and 15 non-coeliac individuals were stained immunohistochemically for COX-2. Samples from 10 of the patients were also stained after these patients had been on a gluten free diet for 6-24 months. Various cell type marker antigens were used for immunohistochemical identification of the type of cell that expressed COX-2. To further verify colocalisation of the cell type marker and COX-2, double immunoperoxidase and immunofluorescence methods were employed. Immunoelectron microscopy was used to investigate the subcellular location of COX-2. RESULTS: In all samples taken from coeliac patients, clusters of cells with strong immunoreactivity for COX-2 were found in those areas of the lamina propria where the epithelium seemed to blister or was totally detached from the basement membrane. These clusters were reduced in number or totally absent in samples taken after a gluten free diet. No such clusters were seen in any control samples. The density of COX-2 positive cells lining the differentiated epithelium decreased significantly from 13.5 (5.1) cells/10(5) microm(2) (mean (SD)) in the untreated patient samples to 6.5 (2.0) cells/10(5) microm(2) after a gluten free diet (p<0.001), and was 3.3 (1.9) cells/10(5) microm(2) in control samples (p<0.001 compared with untreated or diet treated coeliac samples). Staining for COX-2 was localised to CD3+ T cells and CD68+ macrophages in the mucosal lesions but not all of these cells were positive for COX-2. Immunoelectron microscopy revealed that the ultrastructure of the COX-2 positive cells resembled that of lymphocytes, and the immunoreaction was localised to the rough endoplasmic reticulum and the nuclear envelope. CONCLUSIONS: Our results show that in coeliac disease, blistering of small intestinal epithelial cells is associated with accumulation of COX-2 positive T cells, and the number of these cells decreases after a gluten free diet. These observations suggest that COX-2 mediated prostanoid synthesis contributes to healing of the coeliac mucosa and may be involved in maintenance of intestinal integrity.
We reported in the previous paper that rats fed a curdlan diet showed significant increases in the weight of the cecum and its contents, a decrease in fecal wet weight, a retardation in the transit time of the gastrointestinal tract and morphological changes of the ileal and cecal mucosal surface when compared with the rats fed a cellulose diet. In the present study, we intended to learn if the curdlan effects on the morphological structure of intestinal mucosa were reversible. When rats were fed on the curdlan diet for 2 weeks followed by a cellulose diet for another 2 weeks, the cecum and cecal contents were not different from those of the cellulose group. The transit time of the gastrointestinal tract of the curdlan-followed-by-cellulose group was shorter than that of the curdlan group, whereas it was longer than that of the cellulose group. In scanning electron micrographs, the ileal villi of the curdlan-followed-by-cellulose group were normal, as in the cellulose group. However, their ileal and cecal microvilli were similar to those of the curdlan group, that is, the microvilli were crowded and more tightly packed, and some appeared to have been squeezed out. From these results, it was concluded that the effects of the curdlan feeding were only partially reversible, but the effects on the surface structure of intestinal mucosa were still sustained even after curdlan feeding of 2 weeks was discontinued. This might result from response to the high viscosity of the intestinal contents remaining after discontinuation of the curdlan.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
In adult rats topical application of 16,16-dm PGE2 (PGE) every 8 h for three weeks led to a dose-dependent increase of the height of the gastric and duodenal mucosa, especially pronounced in the antrum (+115% with the high dose). In the gastric corpus this resulted from an enlargement of the lamina propria and the epithelial cell mass, the latter mainly from a hyperplasia of the surface and foveolar mucous cells. In contrast, the number of parietal cells was not affected. These findings were corroborated by the observation that an increase of antral mucosal height was also induced by a similar parenteral PGE treatment regimen (dosage 25 micrograms/kg). Both longterm intragastric and intraperitoneal PGE treatment led to an increase in DNA synthesis within the mucosa of the gastric antrum and corpus by 19 to 74%. In a third study 25 or 100 micrograms/kg of PGE applied every 8 h intragastrically to 10 suckling rats from the 7th to 11th postnatal day resulted in a dose-dependent increase in the length of the villi and the disaccharidase activities (30-630%). These studies suggest that 16,16-dm PGE2 exhibits a trophic effect on both the stomach and the small bowel.