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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Ultrasructure Research 85 (1983), S. 249-259 
    ISSN: 0022-5320
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0022-5320
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Ultrasructure Research 77 (1981), S. 210-222 
    ISSN: 0022-5320
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Cell Biology International Reports 14 (1990), S. 44 
    ISSN: 0309-1651
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Heat and mass transfer 36 (2000), S. 557-565 
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The natural circulation loop DANTON at the Dresden University of Technology was designed to investigate the thermohydraulic properties of integrated reactor concepts with a natural circulation driven primary loop. It is not possible to reach a stable two-phase flow in the loop without passing flow instabilities. At an equilibrium of heating and cooling power the flow oscillations can exist at nearly constant frequencies and amplitudes. The oscillating mass flow signal had been investigated by various methods: (a) autocorrelation function, (b) Fast Fourier transformation, (c) estimation of a temporal Liapunov-exponent and (d) reconstruction of the system attractor in a three-dimensional phase space. The selected time-series express a non-linear behaviour, however, they are not chaotic. In comparison to the usual methods the applied analysing methods yield additional information about system frequencies, sensitiveness to disturbances and properties due to non-linear and chaotic behaviour in a natural circulation loop.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 213 (1980), S. 351-360 
    ISSN: 1432-0878
    Keywords: Nucleolus ; Nulceolar organizer ; Lymphocytes ; Phytohaemagglutinin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The nucleoli of lymphocytes from circulating peripheral blood and from phytohaemagglutinin (PHA)-stimulated cultures (from 2 h–96 h) were studied using a silver method, RNA-specific fluorescent staining, and electron microscopy of ultrathin sections. In peripheral blood about 75% of the lymphocytes have one “ring-shaped” nucleolus composed of a distinct fibrillar centre surrounded by a dense pars fibrillaris and little granular material; the remaining lymphocytes showing two or more small “ring-shaped” nucleoli. With PHA stimulation, the number of cells with several nucleoli increases first (from 2 h–12 h). Next, cells containing one or, at most, two large nucleoli with nucleolonema devoid of fibrillar centers are seen (from 4 h on). 34 h after PHA, nucleoli of the “compact” type containing one or more fibrillar centres appear and comprise about 60% of the cells after 72 h. The appearance of more than one nucleolus per cell shortly after PHA administration suggests an activation of additional nucleolar organizer regions (NOR), which fuse to form one or two large nucleoli with nucleolonema. These are then transformed into “compact” nucleoli. The fibrillar centers stain preferentially with silver. They contain nonchromosomal proteins and may serve as stores for nucleolar proteins. The fusion of activated NORs during the first cell cycle explains the relatively high frequency of satellite associations in first mitoses compared to later mitoses after stimulation.
    Type of Medium: Electronic Resource
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 225 (1982), S. 155-163 
    ISSN: 1432-0878
    Keywords: Nucleolus ; Cell cycle ; Lymphocyte ; Phytohaemagglutinin ; Nucleolus-organizer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The nucleoli of lymphocytes undergo a typical sequence of structural changes after stimulation by phytohaemagglutinin. These changes are independent of the cell cycle. Neither the inhibition of DNA-synthesis (by adenosine and methotrexate), nor the elimination of postmitotic interphase nuclei (by a colchicine block of mitoses), nor the release from such blocks has a noticeable effect on nucleolar structure or on the sequence of nucleolar changes. The number of nucleoli per cell is clearly influenced by the cell cycle. Mitosis leads to a marked increase in the number of nucleoli, whereas in all stages of interphase a decrease occurs.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 50 (1911), S. 322-322 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    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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