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  • 1
    Publication Date: 2008-12-05
    Description: Haematopoietic stem cell (HSC) niches, although proposed decades ago, have only recently been identified as separate osteoblastic and vascular microenvironments. Their interrelationships and interactions with HSCs in vivo remain largely unknown. Here we report the use of a newly developed ex vivo real-time imaging technology and immunoassaying to trace the homing of purified green-fluorescent-protein-expressing (GFP(+)) HSCs. We found that transplanted HSCs tended to home to the endosteum (an inner bone surface) in irradiated mice, but were randomly distributed and unstable in non-irradiated mice. Moreover, GFP(+) HSCs were more frequently detected in the trabecular bone area compared with compact bone area, and this was validated by live imaging bioluminescence driven by the stem-cell-leukaemia (Scl) promoter-enhancer. HSCs home to bone marrow through the vascular system. We found that the endosteum is well vascularized and that vasculature is frequently localized near N-cadherin(+) pre-osteoblastic cells, a known niche component. By monitoring individual HSC behaviour using real-time imaging, we found that a portion of the homed HSCs underwent active division in the irradiated mice, coinciding with their expansion as measured by flow assay. Thus, in contrast to central marrow, the endosteum formed a special zone, which normally maintains HSCs but promotes their expansion in response to bone marrow damage.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Xie, Yucai -- Yin, Tong -- Wiegraebe, Winfried -- He, Xi C -- Miller, Diana -- Stark, Danny -- Perko, Katherine -- Alexander, Richard -- Schwartz, Joel -- Grindley, Justin C -- Park, Jungeun -- Haug, Jeff S -- Wunderlich, Joshua P -- Li, Hua -- Zhang, Simon -- Johnson, Teri -- Feldman, Ricardo A -- Li, Linheng -- England -- Nature. 2009 Jan 1;457(7225):97-101. doi: 10.1038/nature07639. Epub 2008 Dec 3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, Missouri 64110, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19052548" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, CD31/analysis ; Blood Vessels/cytology ; Bone Marrow/pathology ; Cadherins/analysis ; Cell Division ; *Cell Movement ; Cell Separation ; Femur/cytology ; Hematopoietic Stem Cells/*cytology ; Immunoassay/*methods ; Immunohistochemistry ; Mice ; Models, Animal ; Osteoblasts/cytology ; Stem Cell Niche/*cytology ; Tibia/cytology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 21 (1980), S. 397-406 
    ISSN: 1432-0630
    Keywords: 73 ; 79.40
    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 influence of the quantum size effect (QSE) in very thin Pd and Au films (0.5〈d〈10 [nm]) deposited on glass tips is studied by means of field emission at various anode potentials. The thickness-dependent field emission current characteristics show short periodic variations with a period of about 0.3 nm for both Pd and Au. The measured QSE oscillations and their amplitudes differ strongly from those expected qualitatively from model calculations for the smallest thicknesses. A model for the metal film based on a modification of the uniform background model is presented, and the thickness dependence of the conductance and the field emission current density are qualitatively discussed. Possible explanations of some discrepancies between calculations and the measured field emission current characteristics are proposed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 10 (1976), S. 265-268 
    ISSN: 1432-0630
    Keywords: 79.40 ; 73
    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 field emission current from thin palladium films deposited on insulating tips in UHV was measured as a function of film thickness at relatively low field strengths. The observed periodic oscillations of the field emission current can be interpreted as the quantum size effect.
    Type of Medium: Electronic Resource
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