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G Neupert

Publications and source records attributed to G Neupert.

At least 19 recordsLinked to original sources
PubMed2007

[Heterotopic pancreas in the gallbladder. Diagnosis, therapy, and course of a rare developmental anomaly of the pancreas].

Ectopic pancreas is a rare entity but the second most prevalent pancreatic anomaly. Heterotopic pancreas is defined as the presence of pancreatic tissue without any anatomic or vascular continuity with the main body of the pancreas. Its aetiology is not clearly established. In 1916, Poppi published for the first time evidence of heterotopic pancreas in the gallbladder. A review of the literature up to the present showed only 28 more cases worldwide of ectopic pancreas in the gallbladder. Aberrant pancreas is incidentally discovered in 2% of autopsies and has been estimated to occur once in every 500 upper abdominal explorations. Ninety per cent of ectopic pancreas is found in the stomach, duodenum, and jejunum. Mostly it is asymptomatic and benign. For this reason, therapy is indicated only in patients with symptoms such as pyloric obstruction, bleeding, and malignant transformation. Surgical resection or endoscopic mucosal resection as a newer method are recommended.

Cholecystectomy, Laparoscopic↗
PubMed1999

PAR 1-type thrombin receptors are involved in thrombin-induced calcium signaling in human meningioma cells.

Thrombin is known to play a role as regulator in tumor spreading and tumor growth. Proteinase-activated receptor 1 (PAR 1)-type thrombin receptors were identified in different cancer cells including human glioblastoma cells. Thus a function of PAR 1 in brain tumors may be suggested. In this study, the presence of PAR 1-type thrombin receptors was investigated in primary cell cultures established from operated human meningiomas from two 59- and 79-year-old women. Characterization of PAR 1 on binding level was performed using immunofluorescence studies with the monoclonal anti-PAR 1 antibody Mab 61-1 directed against a domain in the NH2-terminus of PAR 1. These binding sites constitute functional thrombin receptors that are involved in thrombin-induced signaling in human meningioma cells as demonstrated by investigation of alpha-thrombin- and PAR 1-activating hexapeptide (TRAP-6)-induced [Ca2+]i mobilization. To our knowledge, this is the first report demonstrating thrombin-induced intracellular signaling in human meningioma cells mediated by the PAR 1-type thrombin receptor.

Aged↗
PubMed1998

Functional thrombin receptor PAR1 in primary cultures of human glioblastoma cells.

In this study we investigated primary cultures obtained from two glioblastomas surgically removed from a 64-year-old man and a 50-year-old woman, respectively. The presence of the tethered ligand thrombin receptor PAR1 (protease-activated receptor 1) in these cells was demonstrated at the level of receptor binding by using immunofluorescence studies with the monoclonal anti-PAR1 antibody Mab 31-2. Stimulation of human glioblastoma cells both with alpha-thrombin and the thrombin receptor activating peptide TRAP-6 resulted in a series of [Ca+]i spikes as shown by confocal laser fluorescence microscopy with fluo-3 as calcium sensitive fluorescence indicator. This effect was completely blocked with the thrombin receptor antagonist peptide T1. Our results demonstrate functional thrombin receptors (PAR1) in primary cultures of human glioblastomas for the first time.

Brain Neoplasms↗
PubMed1998

Immunohistochemical localization of cytochrome P450 1A1 in precision-cut rat liver slices after in vitro exposure to beta-naphthoflavone.

Mono- and polyclonal antibodies have been used to study the localization and distribution of cytochrome P450 1A1 (CYP1A1) in cultured precision-cut liver slices with various immunohistochemical methods. Neither in non-incubated slices nor in slices incubated in the absence of beta-naphthoflavone (BNF) for 24 hrs was CYP1A1 immunohistochemically detectable. After incubation in the presence of BNF (25 microM), however, CYP1A1 was well visible in parenchymal and biliary epithelial cells. CYP1A1 was not evenly distributed, but was localized predominantly in hepatocyte layers near the surfaces of the slices. This distribution could be due to the preferential uptake of BNF by outer cell layers or due to functional changes of inner cells. Together with results obtained with other methods (e.g. RT-PCR) this investigation also demonstrates that precision-cut liver slices are a useful tool for the detection of in vitro induction of CYP1A1.

Animals↗
PubMed1992

Metastasis induction by incomplete tumor resection. A new metastasis model using inoculation sarcomas in adult nude mice after long-term cultivation of sarcoma cells.

In searching an animal model to study metastasis formation we used cultured cells of experimental rhabdomyosarcomas and their inoculation tumors in adult nude mice. Supplementing earlier observations (Katenkamp et al. 1987) we found that long-term cultured sarcoma cells induce tumors in adult nude mice which do not metastasize spontaneously but produce lung metastases after repeated incomplete tumor removal. Possible factors and mechanisms responsible for metastasis emergence are discussed. The metastasis model introduced may be apt to study cellular changes at cytogenetic and molecular biological level that occur during tumor progression and metastatic dissemination.

Animals↗
PubMed1991

The glycosaminoglycan metabolism of chondrocyte monolayer cultures under normal and pathological conditions. A methodic study.

Chondrocyte cultures may serve as a model in investigating changes of the cartilage metabolism. Adherent chondrocytes in vitro maintain polygonal morphology at high cell density in the primary and secondary culture. Collagen type II is only clearly detected in multilayered or nodular areas. The differentiation of the chondrocytes is also indicated by a low HA concentration of the cultural medium. It depends on high cell density, a low number of subcultures and their duration. However, the medium GAG of chondrocyte cultures does not exactly mirror the state of cell differentiation but can partly be used to check it. Subcultures of chondrocytes on small cover slides (minicultures) are used to determine proteoglycan synthesis and degradation for 48 h each. Both synthesis and degradation of cell-associated GAG or proteoglycans, resp., follow similar complex kinetics. The half lives of sulfated GAG or proteoglycans are initially 10 h (T-1 for O-6 h of chase), later 39 h or 95 h (T-2 for 6-48 h of chase). Conditioned medium of casein-elicited rat peritoneal macrophages reduce the sulfate incorporation into chondrocyte proteoglycans and their degradation rates increase. In the additional presence of E. coli endotoxin (0.5 microgram/ml) the synthesis of proteoglycans is only little affected; the degradation rate is stronger increased. To peritoneal macrophages of rats manifold pretreated with BCG and perhaps desensitized, LPS is added in vitro. Conditioned medium of these MP does not affect the chondrocyte proteoglycan synthesis but enhances the degradation rates in a concentration-dependent manner. Thus it can be demonstrated that chondrocyte monolayer miniscale cultures may serve to elucidate changes in the proteoglycan synthesis and different degradative steps.

Animals↗
PubMed1991

Bacillus Calmette-Guérin (BCG) influences cell proliferation and glycosaminoglycans of chondrocyte cultures.

There are only few reports on the correlation between bacterial products and the GAG pattern of cartilage. Mycobacteria bovis (BCG) were applied to chondrocyte monolayer cultures for one week. The following parameters did change: cell proliferation increased, glycosaminoglycan synthesis and secretion decreased, hyaluronic acid in secreted and cell-associated glycosaminoglycans increased, a correlation between the degree of these changes and the degree of cell differentiation seems to exist. The contact of bacteria like BCG to chondrocytes may change the cellular metabolism. On the tissue level this may injure articular cartilage and thus support the concept of predamaged cartilage that is readily susceptible to further degradation.

Animals↗
PubMed1991

Isoenzymes of pyruvate kinase, lactate dehydrogenase and alkaline phosphatase in epithelial cell lines of rat liver.

In cultured epithelial cells of rat liver the isoenzyme patterns of pyruvate kinase, lactate dehydrogenase and alkaline phosphatase were studied and compared with those of freshly isolated parenchymal and non-parenchymal liver cells. In all epithelial cell lines pyruvate kinase was not activated by fructose 1,6-bisphosphate, suggesting the absence of the L-isoenzyme. Cell lines derived from livers of newborn rats expressed LDH-4 and -5, whereas cell lines developed from fetal rat livers contained all 5 lactate dehydrogenase isoenzymes. In the latter case the pattern was found to depend on the state of confluence. All cell lines exhibited only a single alkaline phosphatase form, however, differences were found with respect to electrophoretic mobility.

Alkaline Phosphatase↗
PubMed1991

Patterns of cytokeratins and lamins in rat liver and in rat liver cell lines as shown by immunoblotting using the monoclonal antibodies A 45-B/B3 and A 51-B/H4.

The cytokeratins and lamins of rat liver nuclei, nuclear lamina, and cytoskeleton preparations as well as of rat liver cell lines were studied by immunoblotting using the monoclonal broad-range cytokeratin antibodies A 45-B/B3 and A 51-B/H4. A 45-B/B3 is bound to 64-, 58-, 55-, 52.5-, 49-, 45-, 43-, 39-, and 35-kDa proteins, which are already known as rat liver cytokeratins, excepted the 64- and 35-kDa bands. This antibody can therefore be considered to be a pan-cytokeratin marker for the rat. A 51-B/H4 detected an epitope occurring in both lamins (70, 67, and 60-63 kDa) and cytokeratins (49, 45, 43, and 39 kDa). In a few experiments, this monoclonal antibody also indicated a 55-kDa protein. Furthermore, in some cell lines a 80-kDa protein was detected which possibly may correspond to a higher molecular member of the lamin family. In subcellular preparations, the full set of cytokeratins was found to be associated with the nuclei and the nuclear lamina fraction, suggesting a tight connection of the intermediate filaments with the nuclear lamina. Cell lines derived from fetal or neonatal rat liver exhibited cytokeratin patterns which resembled the phenotype of immature or atypically differentiated parenchymal liver cells.

Animals↗
PubMed1990

Experimentally induced murine rhabdomyosarcomas--correlation between cellular contacts, matrix formation and cellular differentiation.

Rhabdomyosarcomas (RMSs) consist of a mixture of primitive mesenchymal cells as well as cells showing various stages of rhabdomyomatous differentiation. The qualitative and quantitative degree of the rhabdomyomatous differentiation of the cells, evaluated by their morphology and expression of defined structural and functional proteins, is accepted as the basis of diagnosis and is considered to be related to the biological behaviour of RMSs. Therefore we investigated solid experimentally induced murine RMSs, adherent (subconfluent, confluent) cell cultures obtained therefrom, and also suspension cultures and studied the expression of muscular differentiation markers (vimentin, desmin, myoglobin) and the formation of extracellular matrix components (fibronectin, laminin). When we compared solid tumours with adherent cell cultures of decreasing cell densities (confluent up to single cells) and with cells grown in suspension, we found a gradual decline of differentiation ("dedifferentiation"). This decline paralleled the decrease of cell-cell and cell-substrate contacts. In suspension cultures, cells were prevented from interacting with each other and the substratum, no rhabdomyomatous differentiation of the cells took place. If restoration of cellular contacts was allowed, either by adherent growth or by reinoculation into nude mice, the process of dedifferentiation was completely reversible. Consequently, it was demonstrated that the increase of cell-cell and cell-substrate contacts was strongly associated with the appearance or increasing expression of the desmin intermediate filament cytoskeleton and with formation of the extracellular matrix components fibronectin and laminin. The microfilament (F-actin) system was modulated from an impressive stress-fiber system in subconfluent to a dense network in confluent monolayers. The extent of cell-substrate contacts, mediated by extracellular matrix components, and the number of cell-cell interactions are responsible for the capability of a malignant mesenchymal cell, which is able to undergo rhabdomyomatous differentiation, to achieve the various stages of maturation.

Animals↗
PubMed1989

Cytokeratin expression in experimental murine rhabdomyosarcomas. Intermediate filament pattern in original tumors, allotransplants, cell culture and re-established tumors from cell culture.

Soft tissue sarcomas were induced by 20-methylcholanthrene in NMRI-mice. The tumors were characterized as rhabdomyosarcomas by light and electron microscopy as well as immunohistochemistry (vimentin, desmin and myoglobin expression). Cytokeratins could be demonstrated by a panel of different poly- and monoclonal antibodies in original rhabdomyosarcomas, their allotransplants and the re-established tumors from cell culture in nude mice. The cytokeratin positive tumor cells were arranged in small clusters and/or haphazardly single dispersed in the rhabdomyosarcomas. By means of monoclonal antibodies cytokeratins No. 8 and No. 19 could be evidenced and cytokeratin No. 18 could be made probably. Behind the background of cytokeratin expression in developing fetal cross striated muscle cells our findings are discussed as a reminiscence of embryonal muscle development in these tumors. The significance of cytokeratin expression in rhabdomyosarcomas for diagnostic histopathology is emphasized.

Animals↗
PubMed1987

Experimentally induced metastases of malignant fibrous histiocytomas xenotransplanted into nude mice from an established sarcoma cell line (RFS).

An experimental approach for inducing metastases from xenotransplanted malignant fibrous histiocytomas in nude mice is presented. Malignant fibrous histiocytomas were generated by inoculation of an established cell line (RFS) in the back of 16 nude mice. 7 nude mice were subjected to diminution operations carried out twice and three times, respectively, 6 out of these animals developed metastases, whereas no metastases were found in the inoperated control group (9 mice). The metastasis formation is explained by sarcoma heterogeneity, some factors which might contribute to the phenomenon of tumor dissemination are discussed.

Animals↗
PubMed1987

Characterization of established epithelioid cell lines derived from rat liver: expression of cytokeratin filaments.

A number of epithelioid cell lines were established from livers of fetal and neonatal rats. The clear-epithelial cells of these lines are non-neoplastically altered, clonogenic, nearly-diploid and showed no hepatocyte-like properties. The distribution and organization of intermediate filaments were analysed by indirect immunofluorescence and immunoperoxidase techniques using polyclonal and monoclonal antibodies against cytokeratins and vimentin. The different keratin antibodies also react strongly with intermediate filaments of bile duct cells on frozen sections of fetal and neonatal liver. Several subcultures of all established cell lines contained cell populations which reacted positively with antibodies against prekeratin and broad-range cytokeratins in a different manner, but not with antibodies against cytokeratin No. 19 of the catalogue of MOLL. The intermediate filaments are arranged in predominantly stained pericellular rings as well as in fine filamentous networks more evenly distributed throughout the cytoplasm. In early passages almost all cells were found positive for pre- and cytokeratins whereas in later subcultures the number of positive cells decreases and the expression of cytokeratin polypeptides varies considerably as seen with the different antibodies. All cells of the different cell lines show a well developed fine filamentous vimentin network extending throughout the whole cell up to the outer cell margin. Our findings support the concept that the clear epithelioid cells in established cell lines are of epithelial nature but they are not derived from biliary epithelium, and therefore probably immature parenchymal liver cells.

Animals↗
PubMed1987

[Significance of scanning electron microscopy observations on cellular reactions in the biological evaluation of endoprosthetic materials].

In a scanning electron microscopic study there are described the adhesion, spreading and formation of confluent monolayers from fibroblasts and epithelioid cells on Al2O3-ceramics and cobalt-basis-alloys in relation to vitreous carbon and glass. The morphogenetic reactions of cultured cells were not significantly different in pattern, behaviour and kinetics on various biomaterials. The cells adhered, spread, migrated and proliferated on the surface of biomaterials to be tested. This allows the conclusion that this implant material is compatible with cells. The variability of properties and susceptibility of cultured cells were discussed as a criterion for biocompatibility of implant materials in preclinical test.

Animals↗
PubMed1986

Modulation of expression of intermediate filaments during the development of established rat liver cell lines.

A number of clear epithelial-like cell lines were established from the liver of fetal and neonatal rats. The intermediate filaments of these cells were investigated using polyclonal prekeratin antisera, monoclonal antibodies against a cytokeratin subfamily and vimentin by means of the indirect immunofluorescence technique and SDS-PAGE analysis. Changes in the expression of cytokeratin filaments were found during the evolution of permanent cell lines. Cells positively stained for cytokeratins could be seen near to other cells which were negative. In early passages (up to the 40th) nearly all cells were strongly stained by the different keratin antibodies. During the following subcultivation the pattern of staining considerably changed. In FRL and NP-RL cell lines keratin-negative cells could already be observed in the early passages, rapidly increasing in the later passages. Compared to this, vimentin-staining of all cells remained constant in its morphological expression. The keratin filaments were seen in thick fiber bundles arranged particularly in the perinuclear ring as well as in finer networks throughout the cytoplasm. Every cell in the established lines showed their very individual staining pattern. The vimentin filaments extended to the whole cytoplasm up to the cell margin. Our observations demonstrate the variability of the system of keratin filaments in established epithelial-like liver cells under cultural conditions.

Animals↗