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  • 1
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The Seragen Cell-ect Total Histamine kitTM was used to separate histamine receptor-bearing rat peritoneal mast cells from cells lacking these receptors. It was found that approximately 75% of the peritoneal mast cell population carried cell surface histamine receptors. The results further suggest that the mast cell histamine receptors present are mainly of an H1-type, as judged by the capacity of a specific H1-antagonist to reduce the histamine receptor-dependent cell adhesion. Moreover, an H1-agonist is less efficient in this respect and an H2-antagonist does not affect the cell adhesion at all. A possible functional role for these receptors, however, remains to be clarified.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of muscle research and cell motility 1 (1980), S. 127-146 
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A peripheral weave of microfilaments is visualized in human glia cells. In this weave small numbers of microfilaments converge to structures in the cell edge. Similar assemblies of microfilaments seem to be attached to structures on the surface of microspikes. Together with filaments splaying from the paracrystalline arrangement in microspikes, these units make up the peripheral weave. The filaments of the weave come in close contact with each other and with filaments of internal actin fibres.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 22 (1992), S. 130-150 
    ISSN: 1059-910X
    Keywords: Electron microscopy ; Scanning electron microscopy ; High resolution ; Cytoskeleton ; Biological specimen preparation ; Cultured cells ; Electrophoresis ; Bifunctional crosslinking reagents ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Today's electron microscopes have a resolution sufficient to resolve supramolecular structures. However, the methods used to prepare biological samples for electron microscopy often limit our ability to achieve the resolution that is theoretically possible. We use whole mounts of detergent-extracted cells grown on Formvar-coated gold grids as a model system to evaluate various steps in the preparation of biological samples for high resolution scanning electron microscopy (SEM)Factors that are important in determining the structure and composition of detergent-extracted cells include the nature of the detergent and the composition of the extraction vehicle. Chelation of calcium is extremely important to stabilize and preserve the cytoskeletal filaments. We have also demonstrated both morphologically and by gel electrophoresis that treatment of cells with bifunctional protein crosslinkers before or during extraction with detergent can significantly enhance the preservation of both proteins and supramolecular structures.The methods used to dry samples are a major determinant of the quality of structural preservation. For cytoskeletons freeze-drying (FD) is superior to critical point-drying (CPD), one reason being that CPD samples have to be dehydrated, thereby causing more shrinkage as compared to FD samples. The high pressures to which samples are exposed during CPD may also cause increased shrinkage, and water contamination during CPD causes severe structural damage. We have obtained the best structural preservation of detergent-extracted and fixed cells by manually plunging them into liquid propane and drying over night in a freeze-drayer.The factor that most limits achievement of high resolution in SEM is the metal coat, which has to be very thin, uniform, and free of grain in order not to hide structures or to create artifactual ones. We have found that sputter-coating with 1-3 nm of tungsten (W) or niobium )Nb( gives extremely fine-grained films as well as satisfactory emission of secondary electrons. These samples can also be examined at high resolution by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The best preservation and visualization of supramolecular structures have been obtained using cryosputtering, in which the samples are freeze-dried and then sputter-coated within the freeze-dryer while still frozen. © 1992 Wiley-Liss, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0741-0581
    Keywords: Cytoskeleton ; Scanning and transmission electron microscopy ; Detergent extraction ; Thin metal films ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: This paper describes the use of sputter coating to prepare detergent-extracted cytoskeletons for observation by scanning (SEM), scanning transmission (STEM), inverted contrast STEM, and transmission (TEM) electron microscopy. Sputtered coats of 1-2 nm of platinum or tungsten provide both an adequate secondary electron signal for SEM and good contrast for STEM and TEM. At the same time, the grain size of the coating is sufficiently fine to be just at (platinum) or below (tungsten) the limit of resolution for SEM and STEM. In TEM, the granular structure of platinum coats is resolved, and platinum decoration artifacts are observed on the surface of structures. The platinum is deposited as small islands with a periodic distribution that may reveal information about the underlying molecular structure. This method produces samples that are similar in appearance to replicas prepared by low-angle rotary shadowing with platinum and carbon. However, the sputter-coating method is easier to use; more widely available to investigators; and compatible with SEM, STEM, and TEM. It may also be combined with immunogold and other labeling methods. While TEM provides the highest resolution images of sputter-coated cytoskeletons, it also damages the specimens owing to heating in the beam. In SEM and STEM cytoskeletons are stable and the resolution is adequate to resolve individual microfilaments. The best single method for visualizing cytoskeletons is inverted contrast STEM, which images both the metal-coated cytoskeletal structures and electron-dense material within the nucleus and cytoplasm as white against a dark background. STEM and TEM were both suitable for visualizing colloidal gold particles in immunolabeled samples.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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