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  • 1
    ISSN: 1432-069X
    Keywords: Key words Kaposi’s sarcoma-derived cells ; Alfa ; interferon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We established long-term cultures from skin tumors of nine patients suffering from classical Kaposi’s sarcoma (KS). Spindle cells obtained after enzymatic digestion were cultured on gelatin- or fibronectin-coated flasks in DMEM with 15% fetal calf serum, aFGF and heparin. Immunohistochemical staining was positive for MHC class I, laminin, type IV collagen, vimentin, α smooth muscle actin (20–40% of cells), caldesmon (20%), calponin (20–40%) and smooth muscle myosin (20–40%), and was negative for common leukocyte antigen, CD4, LFA1, CD34 and cytokeratin. Around 20% of cells up to the third passage in culture expressed the endothelial markers CD36, BMA 120 but were negative for UEA and Fc von Willebrand. Smooth muscle proteins were detected with immunoblotting. Using the polymerase chain reaction, human herpes virus 8 (HHV8) sequences were detected in primary cultures of three out of seven cell lines but were rapidly lost during in vitro passaging. KS-derived cells did not proliferate in serum-free medium, had a normal karyotype and did not grow in soft agar medium. Tumors formed in nude mice injected with KS-derived cells. The tumors were composed of mouse cells and were highly vascularized. Our results suggest that KS-derived cells are heterogeneous: the majority of cells have either a smooth muscle cell or a fibroblastic phenotype. Another minor cell compartment was composed of endothelium-derived cells. KS cells do not possess the characteristics of transformed cells in vitro and may be composed of polyclonal activated cells. Recombinant α interferon (rIFN) slightly inhibited the growth of KS-derived cells and increased the expression of MHC class I antigens. While cells were resistant to natural killer (NK) cell-mediated cytotoxicity, they became sensitive to rIFN-primed NK cells. Thus, the antitumor potential of rIFN against KS in vivo could result from immunomodulatory rather than from direct antiproliferative effects.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-6079
    Keywords: PACS. 36.40.-c Atomic and molecular clusters – 82.33.Hk Reactions on clusters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Spectroscopic experiments have been performed, providing emission and excitation spectra of calcium atoms trapped on argon clusters of average size 2 000. The two experimental spectra fall in the vicinity of the calcium resonance line 1P 1 → 1S0 at 422.9 nm. The excitation spectrum consists in two bands located on each side of the resonance line of the free calcium. In addition, Monte Carlo calculations, coupled to Diatomics-In-Molecule potentials are employed to simulate the absorption spectrum of a single calcium atom in the environment of a large argon cluster of average size 300. The theoretical absorption spectrum confirms the existence of two bands, and shows that these bands are characteristic of a calcium atom located at the surface of the argon cluster and correspond to the excited 4p orbital of calcium either perpendicular or parallel to the cluster surface. The precise comparison between the shape of the absorption spectrum and that of the fluorescence excitation spectrum shows different intensity ratios. This could suggest the existence of a non adiabatic energy transfer that quenches partly the fluorescence of trapped calcium. Another explanation, although less likely, could be a substantial dependence of the calcium oscillator strength according to the alignment of the calcium excited orbital with respect to the cluster surface. The emission spectrum always shows a band in the red of the resonance line which is assigned to the emission of calcium remaining trapped on the cluster. When exciting the blue band of the excitation spectrum, the emission spectrum shows a second, weak, component that is assigned to calcium atoms ejected from the argon clusters, indicating a competition between ejection and solvation.
    Type of Medium: Electronic Resource
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