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  • 1
    ISSN: 1573-6822
    Keywords: cell-cell interactions ; normal human and rat colonic mucosa ; primary culture ; survival factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Primary cultures of normal colonic epithelial cells from both humans (HCEC) and rats (RCEC) have been established using coculture with colon fibroblasts isolated from rat term embryos. While no other factors we have analyzed had any effect on the survival of epithelial cells, which is normally 3–4 days, coculture with viable fibroblasts extended this period to at least 2 weeks. The effects depended on early passages and low seeding densities of the fibroblasts and on direct cell–cell contact. We have obtained cultures of epithelial cells expressing keratin, laminin, and uvomorulin, displaying a polygonal, epithelial morphology and forming microvilli. DNA synthesis as measured by BrdU uptake into DNA varied widely between colonies of the same culture depending on cell morphology: flat colonies of RCECs contained 5.7%±0.56% BrdU-positive cells, while the proportion in dense three-dimensional colonies reached 50.3%±2.6%. In HCECs the growth fraction was lower, but showed the same distribution between classes of colonies. In the presence of rat embryonic colon fibroblasts, growth factors exerted survival activity on colonic epithelial cells. Consecutive addition of insulin and epidermal growth factor/fibroblast growth factor (EGF/FGF) increased colony number (15.0±1.0 and 23.0±2.0 colonies/well respectively; p≤0.05 increased above control) and size (1022±155 and 1207±158 cells/colony respectively; p≤0.05 increased above control) compared to serum-free control medium and basic MEM without growth factors. BrdU labeling index was not increased, however: EGF/FGF actually decreased BrdU labeling from 33.2%±3.9% in controls to 21.3%±3.8% in the EGF/FGF group (p≤0.05) owing to the high proportion of flat colonies consisting of resting cells. The newly established culture model can now be used to investigate growth control mechanisms in colonic mucosa and the effects of toxic and/or tumor-promoting substances on these mechanisms.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0021-9304
    Keywords: basophils ; mast cells ; metal ions ; toxic histamine release ; apoptosis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Recent data suggest that distinct metal ions can be released from dental alloys or other biomaterials, and may cause toxic effects on various cells. In this study, the effects of 14 metal ions on histamine release from human blood basophils (n = 4), isolated tissue mast cells (lung n = 8, uterus n = 2, skin n = 1, gingiva n = 1), the basophil cell line KU-812, and the mast cell line HMC-1 were analyzed. Of the 14 metal ions, Ag+ (0.33 mM) and Hg2+ (0.33 mM) were found to induce release of histamine in blood basophils, KU-812, mast cells, and HMC-1. The effects of Ag+ and Hg2+ were dose dependent and were observed within 60 min of incubation. In primary mast cells and basophils, Au3+ (0.33 mM) also induced histamine release, whereas no effects of Au3+ on HMC-1 or KU-812 cells were seen. The other metal ions showed no effects on primary or immortal cells within 60 min. However, Pt4+ (0.33 mM) induced histamine liberation in HMC-1 and lung mast cells after 12 h. The Ag+- and Hg2+-induced rapid release of histamine from HMC-1 was associated with ultrastructural signs of necrosis, but not apoptosis. In contrast, prolonged exposure to Pt4+ (0.33 mM, 14 h) induced apoptotic cell death in HMC-1 cells, as assessed by electron microscopy and DNA analysis. Together, certain metal ions induce distinct cytopathogenic effects in mast cells and basophils. Whereas Ag+, Hg2+, and Au3+ cause direct toxicity, Pt4+ causes cell death through induction of apoptosis. Whether such effects contribute to local adverse reactions to metal-containing biomaterials in vivo remains to be determined. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 560-567, 1998.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0749-503X
    Keywords: Ashbya ; Eremothecium ; Holleya ; Kluyveromyces ; Metschnikowia ; Nematospora ; Saccharomyces ; Crustaceae ; Diplopoda ; Heteroptera ; Saccharomycetaceae ; phylogeny ; taxonomy ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Phylogenetic relationships between species from the genera Kluyveromyces and Saccharomyces and representatives of the Metschnikowiaceae (Holleya, Metschnikowia, Nematospora) including the two filamentous phytopathogenic fungi Ashbya gossypii and Eremothecium ashbyii were studied by comparing the monosaccharide pattern of purified cell walls, the ubiquinone system, the presence of dityrosine in ascospore walls, and nucleotide sequences of ribosomal DNA (complete 18S rDNA, ITS1 and ITS2 region). Based on sequence information from both ITS regions, the genera Ashbya, Eremothecium, Holleya and Nematospora are closely related and may be placed in a single genus as suggested by Kurtzman (1995; J. Industr. Microbiol. 14, 523-530). In a phylogenetic tree derived from the ITS1 and ITS2 region as well as in a tree derived from the complete 18S rDNA gene, the genus Metschnikowia remains distinct. The molecular evidence from ribosomal sequences suggests that morphology and ornamentation of ascospores as well as mycelium formation and fermentation should not be used as differentiating characters in family delimitation. Our data on cell wall sugars, ubiquinone side chains, dityrosine, and ribosomal DNA sequences support the inclusion of plant pathogenic, predominantly filamentous genera like Ashbya and Eremothecium or dimorphic genera like Holleya and Nematospora with needle-shaped ascospores within the family Saccharomycetaceae. After comparison of sequences from the complete genes of the 18S rDNA the genus Kluyveromyces appears heterogeneous. The type species of the genus, K. polysporus is congeneric with the genus Saccharomyces. The data of Cai et al. (1996; Int. J. Syst. Bacteriol. 46, 542-549) and our own data suggest to conserve the genus Kluyveromyces for a clade containing K. marxianus, K. dobzhanskii, K. wickerhamii and K. aestuarii, which again can be included in the family Saccharomycetaceae. The phylogenetic age of the Metschnikowiaceae and Saccharomycetaceae will be discussed in the light of coevolution. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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