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PubMedDate not supplied

Molecular insights into congenital disorders of the digestive system.

Recent work is providing new insights into molecular mechanisms of digestive system development and their alteration in clinically significant disorders. An understanding of these mechanisms has largely been gained through the use of animal models, because many of the basic processes required in embryogenesis are functionally conserved among species. Such conserved factors include cell-cell signaling pathways and the regulation of gene expression. Disruption of these pathways have been implicated in several congenital disorders of the digestive system, including Hirschsprung disease, malrotation, altered sphincter development, Meckel diverticulum, biliary atresia, Alagille syndrome, pancreatic heterotopias, and pancreatic agenesis. In this review, we highlight recent studies in digestive system development, which elucidate mechanisms underlying congenital disorders of the human digestive system.

Digestive System↗
PubMed2001

Immunohistochemical detection of fibroblast growth factor receptors in normal endocrine cells and related tumors of the digestive system.

Endocrine tumors (ETs) of the digestive system produce several growth factors including acidic and basic fibroblast growth factors (aFGF and bFGF, respectively), which are thought to be involved in the growth of tumor cells and in the proliferation of tumor stromal cells. Their actions depend on binding to four specific receptors--FGFR1, FGFR2, FGFR3, and FGFR4--whose distribution in normal endocrine cells and related tumors of the gastroenteropancreatic (GEP) system has previously been examined. Formalin-fixed, paraffin-embedded normal tissues and 60 well-characterized GEP endocrine tumors were immunostained using specific antibodies directed against various GEP hormones, aFGF, FGFR1, FGFR2, FGFR3, and FGFR4. Acidic FGF immunoreactivity (IR) was found in gut EC cells; FGFR1 immunoreactivity in rare duodenal endocrine cells and in pancreatic A cells; FGFR2 immunoreactivity in gastric and duodenal G cells, pancreatic B cells, and rectal EC cells; FGFR3 immunoreactivity in duodenal G cells; and FGFR4 immunoreactivity in rectal L cells and in pancreatic B, PP, and A cells. Immunoreactivity for at least one of the four FGFRs was found in all tumors, independently of FGFR expression in the putative cell of origin. EC cell tumors, which were all positive for aFGF, were found to express at least three different FGFRs. FGFRs also were localized in the stromal cells of all the tumors examined. The tumor stroma was more abundant in EC cell tumors than in other types of neoplasms. The results suggest that aFGF-FGFR interaction may be involved in the modulation of normal endocrine cell functions and in the regulation of tumor growth and stromal proliferation of EC cell carcinoids.

Adolescent↗
PubMed1982

[New stage in the study of the central effects on digestive system functions].

The review included author's own studies and emphasizes the problem of peptides participating in transmission of central influences to the intramural nervous system in the digestive tract's organs, to their endocrine cells or directly to the secretory (or smooth muscle) cells. The role of endocrine apparatus of the digestive tract's organs is discussed as well as the role of the so called peptidergic fibers of the vegetative nervous system in regulation of secretory function of the stomach and pancreas.

Animals↗
PubMed1993

Expression of growth factor peptides and their receptors in neuroendocrine tumors of the digestive system.

Neuroendocrine tumors of the digestive system are slow growing neoplasms which often present with pronounced fibrosis around tumor cells and in the peritoneal cavity. In this report 30 midgut carcinoids and endocrine pancreatic tumors were examined for the expression of peptide growth factors and their receptors, both by immunohistochemistry and in situ hybridization. Our data indicate that multiple peptide growth factors, PDGF, TGF-beta, and bFGF are expressed by these tumors. PDGF was expressed on tumor cells and stroma in 70% of tissues examined. PDGF alpha-receptor was seen on clusters of tumor cells and occasionally on adjacent stroma, whereas PDGF beta-receptor was seen only in the stroma. Our data suggest that PDGF may be involved in the autocrine stimulation of tumor cells and stimulation of stromal cell growth through paracrine and possibly autocrine mechanism. In addition, tumor tissues express all three isoforms of TGF-beta in more than half of the tissues examined. Tumor cells produce small latent complexes causing an escape from potent inhibitory effect of TGF-beta and stimulation of stromal cell growth and matrix deposition through paracrine mechanism. bFGF, a potent stimulant of endothelial cell growth, was expressed by all tumor tissues examined. Our data suggest that multiple peptide growth factors may have an important role in tumor progression and desmoplastic reaction accompanying these tumors.

Adenoma, Islet Cell↗
PubMedDate not supplied

Expression of transforming growth factors beta 1, beta 2, beta 3 in neuroendocrine tumors of the digestive system.

Neuroendocrine tumors of the digestive system are slowly growing neoplasms which often present pronounced fibrosis around tumor cells and in the peritoneal cavity. In this study, 23 midgut carcinoids and 7 endocrine pancreatic tumors were examined for the presence of TGF-beta with affinity-purified polyclonal antibodies raised against synthetic peptides coding for a specific region of latency-associated peptide sequences of TGF-beta 1, -beta 2, -beta 3, a rabbit anti serum against TGF-beta binding protein (LTBP) and a rabbit polyclonal antibody against TGF-beta type II-receptor (TGF-beta RII). Tumor cells from most tissues expressed all three isoforms of TGF-beta but LTBP was only weakly expressed. In stromal cells abundant expression of TGF-beta 2 and LTBP was found, whereas TGF-beta 1 and TGF-beta 3 were expressed only weakly. TGF beta RII immunoreactivity was observed mostly in the stromal cells. Tissue sections from 4 of these neuroendocrine tumors were also investigated by in situ hybridization. Strong signals on tumor cells were detected with TGF-beta 2 and TGF-beta 3 cRNA probes and also weakly with TGF-beta 1 and LTBP cRNA probe. Strong positive signals were observed on stromal cells with TGF-beta 2 and LTBP probe whereas only weak signals were observed on the stromal cells with TGF-beta 3 probe. Strong signals were detected on stromal cells with TGF-beta RII probe whereas no signals were observed on tumor cells. Our data suggest that TGF-beta might play an important role in the interaction of tumor and stromal cells. Thus TGF-beta might stimulate matrix production and angiogenesis of stromal cells, whereas tumor cells themselves are unaffected by the growth inhibitory activity of TGF-beta.

Adenoma, Islet Cell↗
PubMed2004

Analysis of the performance of an anaerobic digestion system at the Regina Wastewater Treatment Plant.

From the performance analysis of the anaerobic digestion system at the Regina Wastewater Treatment Plant, it was found that the anaerobic digestion system at the Regina plant was generally operated in a stable condition as indicated by pH, volatile acids and alkalinity levels. The operation of the anaerobic digestion system was not optimal because of the low volatile solids concentration and low volatile solids loading rate, especially because of high HRT. Two options, thickening the primary sludge and increasing the volatile solids loading rate, were recommended for the optimal operation of the digestion system. After examining a number of kinetic models, it was found that the Chen-Hashimoto model could be used to predict the volumetric methane production rate and the first-order model could be used to predict the efficiency of volatile solids reduction. The study showed that utilization of digester gas for power production was the best alternative for the excess digester gas. 13.3% of the electrical demand and 35.5% of the plant's total energy could be met based on digester gas wasted, assuming 25% as the conversion efficiency.

Bacteria, Anaerobic↗
PubMed2003

Cholesterol crystal embolization to the digestive system: characterization of a common, yet overlooked presentation of atheroembolism.

In the 1359 published patients with multiorgan cholesterol crystal embolism (CCE), the digestive system seems to be the third most frequently affected system. Yet, this system received hitherto only little attention in the medical literature. Therefore, the aim of the present study was to clinically characterize the subset of patients with CCE involving the digestive system, based on our institutional experience and a review of the literature. Cases with CCE in a 7-yr period (1995-2001) were sought in the computerized records of our medical center. Of the CCE patients, those with digestive system involvement that could be related to CCE were included in this study. The clinical features of CCE were determined and compared with those found in published series. Fourteen cases with CCE were identified, giving an annual incidence of 0.8 per 10(5). Digestive system involvement was found in five (36%) of the 14 patients. All five patients had established atherosclerosis. Precipitating factors were vascular manipulations or anticoagulation treatment in four of these five patients. Two patterns of disease appeared: acute catastrophic multiorgan disorder with poor prognosis and chronic and more indolent GI disease. Abdominal pain, GI bleeding, fever, and diarrhea were the most common manifestations, resulting from bowel infarction, mucosal ulcerations, hepatocellular liver disorder, and/or pancreatitis. CCE is a systemic disorder with a frequent involvement of the digestive system and protean clinical manifestations. It should, therefore, be considered in any gastroenterological patient with atherosclerosis and recent vascular manipulations or systemic anticoagulation.

Aged↗
PubMed1990

Environmental diseases of the digestive system.

Environmental factors are important mediators of many diseases of the digestive system, defined as the alimentary tract and the accessory organs of digestion, the liver and pancreas. In this review, we principally focus on the action of chemical agents which are classified as (1) naturally occurring compounds, (2) occupational hazards, (3) therapeutic drugs, and (4) constituents of substances of abuse. In addition, the putative role of dietary habits in the pathogenesis of malignant diseases of the digestive system is discussed.

Alcohol Drinking↗