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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 31 (1995), S. 267-274 
    ISSN: 1059-910X
    Keywords: Preparation technique ; Artefacts ; Sectioning-induced texture ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The methodology and one of the first attempts to produce transmission electron microscopic (TEM) specimens of nanocrystalline metals, alloys and ceramics by ultramicrotomy are presented. Samples of the pure elements Co, Pd; alloys of Y-12 at.% Fe, Al-7 at.% Ag and W-30 at.% Ga; and ZnO ceramic, were found to section successfully to varying degrees. Advantages of sections prepared through ultramicrotomy over ion beam methods include extensive electron-transparent regions of uniform thickness and absence of ion beam damage. Typical artefacts were observed (knife marks, tearing, pull-out, shear lamellae, section curling, and anodic dissolution) but did not impede TEM analysis significantly. A potentially important effect observed was that of a texture development upon sectioning of the Co and Pd samples. It is thought that this unusual phenomenon results from the extremely fine scale of the microstructure and the purity of the Co and Pd samples, and may be enhanced by frictional heating effects and the state of the knife edge. © 1995 Government of Canada.Exclusive worldwide publication rights in the article have been transferred to Wiley-Liss, Inc., in perpetuity.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0003-276X
    Keywords: Collagen fiber alignment ; Bone strain ; Biomechanics ; Calcaneum ; Talocrural joint ; Ovis aries ; Circularly polarized light microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: Gebhardt (1905. Arch. Entwickl. Org., 20:187-322) originated the hypothesis that the direction of collagen fibers in bone is a structural response to the type of mechanical load to which the bone is subjected. He proposed that collagen fibers aligned parallel to the loading axis are best suited to withstand tensile strain, whereas fibers oriented perpendicular to the loading axis are best able to resist compressive strain. Research comparing load patterns with fiber alignment in bone have tended to support Gebhardt's hypothesis. The aim of the present study is to further test this hypothesis by assessing the correspondence between the distribution of strain and the distribution of collagen fiber orientation in a bone that is subjected to compound loading (i.e., both tension and compression at different phases during the loading cycle). The ovine calcaneum was selected to meet this criterion.Methods: Calcaneum surface strain distributions were obtained from experimental results reported by Lanyon (1973. J. Biomech. 6:41-49). Histological sections of the calcaneal shaft were prepared and observed using circularly polorized light (CPL) microscopy to determine the distribution of collagen fiber alignment. The observed alignment pattern was then compared with the predicted pattern based on Gebhardt's hypothesis.Results: Contrary to previous studies, our findings show no clear correspondence between the strain type of greatest magnitude and the direction of collagen fibers. Areas of bone characterized by high compression and low tension showed predominantly longitudinal collagen alignment (contra to Gebhardt).Conclusions: It is argued that even small magnitudes of tension operating on local areas of bone may be sufficient to induced collagen alignment favorable to this type of strain, even when greater magnitudes of compressive strain are acting on the same bone volume. © 1995 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    BioEssays 7 (1987), S. 159-164 
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cellular differentiation is often accompanied by the expression of specialized plasma membrane proteins which accumulate in discrete regions. The biogenesis of these specialized membrane domains involves the assembly and co-localisation of a spectrin-based membrane skeleton. While the constituents of the membrane skeleton in non-erythroid cells are often immunologically related to erythroid spectrin, ankyrin, and protein 4.1, there are structural and functional differences between the isoforms of these membrane skeleton polypeptides, as well as highly variable patterns of expression during cellular differentiation. We consider this heterogeneity of structure and expression during development in the context of the hypothesis that non-erythroid spectrin, ankyrin, and protein 4.1 are involved in the formation of specialized membrane domains.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A separation procedure has been developed for mouse splenic T and B lymphocytes which is based on their differential agglutination by wheat germ agglutinin (WGA). In the presence of 50-100 μg/ml of WGA, multicellular aggregates are formed which are enriched in B cells. These aggregates can be separated from monodisperse T cells by gravity sedimentation and subsequently dissociated into single cells by treatment with N-acetylglucosamine (NAG). Immunocytochemical analyses and mitogenic assays indicate approximately 10-15% cross contamination of the resultant B and T cell fractions. The separation procedure is not only convenient and rapid but also allows the simultaneous recovery of viable T and B cells from the same spleen preparation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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