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A Stallmach

Publications and source records attributed to A Stallmach.

87 records · Page 5Linked to original sources
PubMed1991

[Cell membrane binding components for constituents of the extracellular matrix: structural mediator of the epithelial matrix interaction in the gastrointestinal tract].

Growth, migration, differentiation and metabolic functions of the epithelium in the gastrointestinal tract are regulated by the extracellular matrix. Different cell membrane binding components including the integrins for constituents of the extracellular matrix are expressed in the epithelial cells. These cell membrane binding components may be structural mediators of cell-matrix interaction in the gastrointestinal tract. A characterization of this interaction is of great importance, not only to understand physiological processes, such as epithelial migration and differentiation, but also for the pathogenesis of healing processes (ulcer healing), immunologically mediated processes (adhesion of immunocompetent cells), and especially for tumor pathology (invasion and metastasis). Gastrointestinal diseases are characterized by alterations in the expression of cell membrane binding components for different constituents of the extracellular matrix. In chronic inflammatory bowel disease, a changed expression can be identified on epithelial cells and, in especially malignant transformation of epithelial cells resulted in a pathologic expression of cell adhesion molecules. Oncogenes may modify the expression and function of these cell membrane binding components in the course of malignant transformation. In animal models, it was possible to reduce the frequency of tumor invasion and metastasis and to achieve longer survival times by blocking the cell membrane binding components on malignant cells. An increasing understanding of the role of cell membrane binding components in the epithelium-matrix interaction will certainly also be translated in the future into new therapeutic concepts.

Cell Adhesion↗
PubMed1990

Basement membrane components are potent promoters of rat intestinal epithelial cell differentiation in vitro.

Basement membranes have been implicated in morphogenesis and cell differentiation. In this study, the effect of basement membrane components on intestinal epithelial cell maturation in a mesenchyme-free environment was investigated. Fetal rat small intestinal epithelial cells (from the 14th-17th day of gestation) were exposed to basement membrane-derived proteins (laminin, collagen type IV, and a complex basement membrane-enriched extract from the Engelbreth-Holm-Swarm sarcoma) and other extracellular matrix proteins (collagen type I and fibronectin) coated onto Petri dishes. The cells attached readily only to fibronectin and basement membrane proteins. For 5 days the developing epithelial colonies were monitored in vitro, assessing morphological and functional parameters of cell maturation. Colonies grown on laminin and the basement membrane extract were larger and of greater cell density. An increase in alkaline phosphatase and lactase activity was observed after 3-4 days in these colonies which could be enhanced to yield 90%-100% positive cells by the addition of dexamethasone to the medium while no sucrase-isomaltase activity was elicited. Electron microscopy confirmed a high degree of cellular polarization illustrated by tight junctions and apical microvilli in epithelial cells grown on a basement membrane-like support. In contrast, none of the other proteins stimulated the cells to mature in vitro. The authors conclude that certain basement membrane components actively promote fetal intestinal epithelial cell differentiation.

Animals↗
PubMed1990

Identification of laminin binding proteins in cell membranes of a human colon adenocarcinoma cell line.

The invasion of malignant cells through the basement membrane is a critical step in local infiltration and metastasis. Adhesion and invasion of malignant cells may be modulated by their receptor mediated binding to the basement membrane glycoprotein laminin. We studied the specific adhesion of human colon adenocarcinoma derived HT 29 cells to laminin and its proteolytic fragments. The major cell adhesion domain of laminin was localised in the central part of the cross shaped molecule. Immunoblotting experiments on separated HT 29 cell membranes using specific antibodies or radiolabelled laminin fragments revealed two major laminin-binding cell surface components with Mr of 67,000 and 69,000 D similar to the putative laminin receptor described for other tissues. Using a nitrocellulose filter disk assay, the specific interaction between cell surface binding proteins and proteolytic fragments originating from the central core of the laminin molecule could be further corroborated. In contrast, interaction of HT 29 cell membranes with the pentapeptide YIGSR (tyr-ile-gly-ser-arg), a sequence domain of the B1-chain of the laminin molecule, thought to be responsible for cell adhesion, was significantly weaker.

Adenocarcinoma↗
PubMed1990

Laminin-cell membrane binding proteins in small intestinal epithelial cells.

The regulation of cell proliferation, migration and differentiation under physiological conditions and in adaptational patterns is still not well understood. The interaction of intestinal epithelial cells with the basement membrane may influence cell adhesion and migration. One potential mechanism involves cell surface binding proteins, which induce the biological response when occupied by the basement membrane component. Immunoblotting experiments on isolated epithelial cell membranes from the normal duodenum of adult rats using specific antibodies revealed major laminin-binding cell membrane components with an Mr of 66-69 kD, similar to the putative laminin receptor described for other tissues. The specific interaction between these cell membrane binding proteins and the proteolytic fragment laminin P1 originating from the central core of the laminin molecule could be further demonstrated by slot blot assays. Immunohistological examinations of normal small intestinal mucosa revealed that the 67-kD laminin-binding proteins were present on the basolateral cell surfaces of epithelial cells lining the base of the crypt of Lieberkühn, but were absent from cells lining the mouth of the crypts or the villi.

Animals↗
PubMed1990

The role of gut-glucagon-like immunoreactants in the control of gastrointestinal epithelial cell renewal.

In vitro and in vivo studies have provided considerable information on the possible physiologic function of circulating gastrointestinal hormones as well as locally acting regulatory peptides in the multifactorial control of adaptive gastrointestinal epithelial cell proliferation and cell renewal. It has been suggested by circumstantial evidences that enteroglucagon (EG; G-GLI I) may act as a trophic factor on the intestinal mucosa which may account for adaptive changes of the small intestine following various stimuli. However, we have shown that there are experimental conditions (germ-free rats after conventionalisation; jejunal self-filling blind loops) in which intestinal hyperplasia does not correspond to an increase in the concentrations of enteroglucagon in plasma or intestinal mucosa. Furthermore, despite a continuous immunoneutralisation of circulating endogenous enteroglucagon by monoclonal antibodies there was an adaptive, hyperplastic response of the ileal remnants after a 70% proximal small bowel resection which was of the same magnitude as in the control group but was even greater considering the increased number of mitoses per crypt. In order to gain additional insight into the putative role of enteroglucagon as an enterotrophic regulatory peptide, an in vitro model was used to investigate the effect of highly purified rat G-GLI I on the proliferative response of primary small intestinal epithelial cells of fetal rats. Whereas there was a well known growth-promoting action of EGF, the proliferation of rat fetal intestinal epithelial cells was inhibited by the addition of purified G-GLI I. These results indicate that enteroglucagon does not act as an enterotrophic factor but provide the first direct evidence consistent with an antitrophic role of enteroglucagon in the small intestine.

Adaptation, Physiological↗
PubMed1989

Immunohistochemical and electron microscopic study of interaction of Yersinia enterocolitica serotype O8 with intestinal mucosa during experimental enteritis.

The experimental infection of mice with Yersinia enterocolitica serotype O8 was investigated in a quantitative and histological study. The course of bacterial penetration and spreading was precisely determined by immunohistochemical staining. After oral administration, the bacteria passed the epithelial barrier of the ileum and spread into the lamina propria. By preference they entered Peyer's patches, which were about 1,000 times more heavily colonized than the surrounding epithelium of a comparable surface area. The bacteria proliferated in the follicles, from which they spread into the lamina propria of the villi. At either site most of the bacteria multiplied extracellularly, with only a small percentage observed to be present within the phagocytes. The bacteria did not appear to be able to pass the intact basement membrane; hence, the integrity of the basement membrane is likely to play a role in determining the route of entry and limit of spread of Y. enterocolitica infection.

Animals↗
PubMed1989

Differentiation of rat intestinal epithelial cells is induced by organotypic mesenchymal cells in vitro.

Stromal-epithelial interaction is a potent driving force in the developing intestinal mucosa which ensures tissue specific cellular differentiation. The mechanisms involved are relevant to tissue renewal in adult organs yet they have not been elucidated because of the lack of appropriate in vitro models. In this study, we have investigated the interaction between intestinal mesenchymal and epithelial cells at the cellular level in vitro. Fetal rat intestinal epithelial cell colonies explanted in vitro on the 15th day of gestation, which failed to mature in plain monocultures, were reassociated in coculture with three different types of mesenchyme:fetal skin, gastric and intestinal mesenchyme. Only fetal epithelial cells cocultured with intestinal (homologous) mesenchyme acquired definite signs of differentiation within three to six days. These primitive epithelial cells were shown by electronmicroscopy to become highly polarized, connected by tight junctions and covered with a regular brush border. Three brush border enzymes were strongly expressed in homologous cocultures and their activity was sensitive to dexamethasone. In contrast, fetal epithelial cells cocultured with skin or stomach derived mesenchyme under identical conditions failed to differentiate in vitro: they remained flat, unpolarised and expressed only low enzyme activity. The unique potential of the small intestinal mesenchyme to promote intestinal epithelial differentiation is discussed.

Animals↗
PubMedDate not supplied

Whipple's disease with aortic regurgitation requiring aortic valve replacement.

Cardiac involvement in Whipple's disease is well established. However, clinical consequences beside antibiotic therapy have rarely been reported. Our observation of a middle-aged man with increasing dyspnea, fatigue, chest pain, and dizziness leading to admission to a cardiology department demonstrates that cardiac symptoms may represent the main symptoms in patients with Whipple's disease. The diagnosis was not made prior to upper endoscopy, performed because of diarrhea, and revealed Whipple's agent now classified as Tropheryma whippelii, which is a PAS-positive rod-shaped bacterium in the macrophages of the intestinal lamina propria. The aortic valve was replaced after the intestinal symptoms were resolved by antibiotic treatment reducing the number of infectious agents in the duodenal mucosa. Histological analysis of the aortic valve demonstrated the presence of PAS-positive rod shaped material as the most likely cause of aortic insufficiency. Five months after valve replacement, the patient had completely recovered from intestinal and cardiac symptoms. Still under antibiotic treatment 16 months later, no more PAS-positive macrophages were detectable in the intestinal mucosa.

Aortic Valve↗
PubMedDate not supplied

Effects of gliadin peptides B1-B4 in celiac disease. I. Organ culture studies.

Small intestinal organ culture was used as an in vitro system to study the enterotoxic effects of gliadin peptides. Measurement of enterocyte height proved to be a reliable and reproducible way of assessing mucosal change during organ culture. Enterocyte height decreases nonspecifically in normal cultured mucosa, whereas the height of enterocytes of celiac mucosa increases in vitro in controls. All the gliadin peptide fractions (B1, B2, B3, B4) that had been prepared by peptic-tryptic hydrolysis, ultrafiltration, and gel chromatography, equally inhibited the morphological increase of enterocyte height normally observed without gliadin in untreated celiac mucosa. Electrophoretic studies and amino acid analysis of B1-B4 revealed similarity between gliadin fractions with quantitative differences in molecular weight distribution of the peptide components. Our studies suggest that organ culture assessed by morphometry is a suitable model for the investigation of toxic peptides of gliadin in celiac disease. In the future, pure gliadin peptides will have to be examined.

Atrophy↗
PubMedDate not supplied

Decreased Helicobacter pylori-specific gastric secretory IgA antibodies in infected patients.

Despite an increase in local Helicobacter pylori-specific IgA production in H. pylori infection, the bacterium is able to persist over decades. We focused on IgA and secretory IgA (sIgA) in gastric juice because sIgA is more relevant in local protection and more resistant to degradation than nonsecretory IgA. H. pylori-specific IgA and sIgA in gastric juice, saliva, and serum of H. pylori-infected patients were compared. Samples from 28 H. pylori-positive and 16 negative patients were tested by means of immunoblotting for the presence of H. pylori-specific IgA and sIgA. In gastric juice the majority of H. pylori-specific IgA was not of the secretory type, whereas total IgA was bound mainly to the secretory component as shown by immunoblot and slot blot. In contrast H. pylori-specific IgA antibodies in saliva of infected patients were of the secretory type as shown by immunoblot. The presence of specific, nonsecretory IgA may be a consequence of the damaged mucosal epithelium at the site of H. pylori infection allowing IgA to bypass the secretory transport system. Considering the resistance of secretory IgA against hydrolysis and proteolysis, these data suggest that the predominantly nonsecretory IgA specific for H. pylori may lead to a decreased protection against H. pylori.

Adult↗