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  • 1
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary On solid substrates MDCK, a cell line derived from normal dog kidney, forms a confluent monolayer that is studded with “blisters”. Previous studies with this cell line suggest that these hemicysts develop as a result of active fluid accumulation between cell sheet and substratum. One factor that may determine when and how hemicysts appear only in localized sites is the interruption of occluding junctions in nonhemicyst areas. To study this possibility, we compared the permeability characteristics of the occluding junctions in hemicysts and in an uninterrupted monolayer of MDCK grown on a permeable support of collagen-coated nucleopore filter. The spontaneous electrical potential differences were small, without statistical differences between them. Relative ionic permeability coefficients were evaluated from the voltage deflections to imposed salt gradients or to a single ion substitution across both structures. The results showed that the relative permeability ratios for Na+, K+, choline+, and Cl− were the same in hemicysts and the uninterrupted monolayer. These and other results indicate that the junctional complex encircling the apical surface of a sheet of MDCK cells can provide an effective permeability barrier constituting a true occluding junction with the same properties in hemicyst and nonhemicyst areas.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 75 (1968), S. 0 
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Clinical & experimental metastasis 4 (1986), S. 91-104 
    ISSN: 1573-7276
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Bovine capillary endothelial cells (BCEC), cultured in suspension on a rotary shaker, formed aggregates ranging from 50 to 300 µm in diameter. In plasma clot these aggregates sprouted in multiple directions and gave rise to vascular channels. Aggregates of the squamous cell carcinoma line of rat bladder NBT-II-81, cultured in plasma clot, formed solid spheroids that grew slowly by expansion. When cultured together with BCEC, however, NBT-I I-81 infiltrated the plasma clot extensively. The tumor cells, after establishing contacts with the vascular channels, spread into the fibrin meshwork using the subendothelial space as their path of propagation. Endothelial cells that were separated from the surrounding matrix by invading tumor cells degenerated, leaving behind channels lined only by neoplastic epithelium. The adhesive properties of the subendothelial matrix were studied by seeding NBT-I I-81 cells on dishes coated with the extracellular matrix produced by BCEC. Tumor cells attached readily and in large numbers to dishes coated with the subendothelial matrix. In contrast they attached poorly to dishes coated with fibrin. We conclude that the spread of carcinoma cells into plasma clot is markedly enhanced by endothelial channels, developed in the absence of blood flow. The production of a highly adhesive extracellular matrix by the capillary endothelium during angiogenesis may represent an important element in the preferential growth of the tumor along the vascular route.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 259 (1976), S. 220-222 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It has been shown that cyclic AMP may influence factors of the cellular membrane such as concanavalin A (con A) agglutination12, surface antigens on cells13, morphology of cells14, contact inhibition of growth15, and adhesion of cells to glass16'17. We report here that dibutyryl (db) cyclic AMP and ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cancer and metastasis reviews 3 (1984), S. 81-97 
    ISSN: 1573-7233
    Keywords: histophysiologic gradient ; aggregate replication ; neoplastic blockade
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effective study of the malignant phenotype at the tissue level requires model systems that are intelligible both to cell biologists and to pathologists, and that also observe the spatial imperatives intrinsic to tissues in nature. Malignant cells commonly appear in multicellular units, and growth of tumor tissue is seen as an increase in the number of cells and multicellular units. The supporting stroma frequently has an abnormal appearance, and this component of the tissue also increases in mass as the tumor enlarges and spreads. The direction of invasion is influenced by the direction of available metabolites. Histophysiologic gradient culture complies with nature's spatial rationale, since at the substrate-parenchymal interface three functions coincide. These are anchorage, initiation of epithelial renewal, and complete exchange of metabolites. Our model system provides a setting for reconstructing and manipulating many features of the malignant phenotype seen in cancer tissues in nature, such as abnormalities in the sequence of maturation of stratified epithelium, hyperplasias, dysplasias, interaction between different types of epithelium, aggregate formation, tumor angiogenesis, and neoplastic blockade.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 29 (1994), S. 375-382 
    ISSN: 0886-1544
    Keywords: collagen ; actin ; α-actinin ; cAMP-dependent protein kinase ; NBT-II cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cyclic AMP (cAMP) has been implicated in the regulation of movement of certain cultured cell types. We have studied the effects of cAMP on epithelial cell motility using serum-free NBT-II cells, derived from a rat bladder carcinoma. The random movement of these cells on type I collagen was reduced upon elevation of intracellular cAMP by several means and this effect was reversible. Alterations in the organization of the cytoskeletal proteins F-actin and α-actinin occurred concurrently with the reduction in motility, and the arrangement of these proteins resembled that seen in non-motile cells on glass. In addition, pretreatment of cells with KT5720, a cAMP-dependent protein kinase (PKA)-specific inhibitor, prevented the dibutyryl cAMP-induced reduction in cell movement as well as the associated cytoskeletal changes. These results suggest that elevation of PKA is responsible for the observed effects on cell motility and cytoskeletal reorganization and demonstrate a role for PKA in the regulation of cell motility in this system. © 1994 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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