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  • 1990-1994  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Rumpshaker mouse: A new X-linked mutation affecting myelination: Evidence for a defect in PLP expression (1990)
    Springer
    Journal of neurocytology 19 (1990), S. 273-283 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This report describes a new X-linked mutation in mice, named rumpshaker (rsh) which is associated with hypomyelination of the central nervous system. Myelination commences appropriately but the majority of sheaths fail to develop normally. Oligodendrocytes are increased in number and have prominent Golgi apparatus, rough endoplasmic reticulum and free ribosomes. Occasional cisternae of rough endoplasmic reticulum are distended. Some dense lamellar inclusions occur in Oligodendrocytes but overall, degenerative changes and cell death are uncommon. Immunostaining demonstrates a major defect in expression of PLP/DM-20. Using site-specific antisera directed at different portions of the PLP/DM-20 molecule, the major defect appears to be with PLP where virtually no myelin sheaths are positive. Antiserum against the C-terminal common to PLP and DM-20 shows reduced but definite myelin staining. Genetic analysis indicates a locus at or close to the PLP/jimpy (jp) locus. The rsh mutation, however, differs fromjp in that affected mice have normal longevity, can breed, produce substantially more myelin and have increased numbers of Oligodendrocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01217305
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Po gene expression in cultured Schwann cells (1991)
    Springer
    Journal of neurocytology 20 (1991), S. 769-780 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study examines the expression of the major myelin protein gene Po in cultured Schwann cells, grown on their own or in association with neurons. Many freshly dissociated Scwhann cells from actively myelinating nerves express Po mRNA in high abundance. If neurons are not present, signal intensity falls markedly with time so that by 7 days in culture only a basal expression is evident which is negligible compared to the levelin vivo. Dorsal root ganglia from embryo day 16 (E16) rats contain no significant levels of Po mRNA but when grown in full myelinating medium (containing serum and embryo extract) increasing expression is seen from 4 to 5 days onward even though myelination does not occur until after the second week. In this intervening period the intensity of Po mRNA expression is lower than that found in the actively myelinating cell. Neurons from sympathetic ganglia are also capable of inducing Po mRNA expression. Schwann cells in dorsal root ganglia explants grown in serum-free defined medium do not assemble a basal lamina and will not wrap or myelinate axons. Nevertheless Po mRNA, but not protein, is expressed in levels similar to those found in full myelinating medium prior to myelination. Such Schwann cells also exhibit galactocerebroside and the sulphatide recognised by the 04 antibody. It appears that in defined medium or in myelinating medium prior to myelination axonal signals can induce Po mRNA expression to a certain degree. However, full up-regulation is usually associated with the rapid membrane expansion accompanying myelination. Whether this augmented up-regulation is due to further axonal signalling or events in the Schwann cell is unknown, but the results suggest that Po expression can be regulated at several stages of synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01187850
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    In vitro studies of axonally-regulated Schwann cell genes during Wallerian degeneration (1993)
    Springer
    Journal of neurocytology 22 (1993), S. 590-602 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Wallerian degenerationin vivo is associated with marked downregulation of myelin protein genes such as Po and upregulation of other genes such as nerve growth factor receptor (NGF-R), glial fibrillary acidic protein (GFAP) and neural cell adhesion molecule (N-CAM). This study examines the expression of these genes during Wallerian degenerationin vitro and how manipulating Ca2+ affects this response. Small explants of sciatic nerve from normal young adult rats cultured for five days show similar reversal of the myelinating phenotype as foundin vivo. If Ca++ is removed from the culture medium through the addition of EGTA, expression of the nerve growth factor receptor and glial fibrillary acidic protein genes is inhibited but downregulation of the Po gene still occurs. Explants cultured in medium containing EGTA are still capable of expressing nerve growth factor receptor if the medium is replaced by one containing Ca2+. Supplementation of normal medium with drugs modulating Ca2+, such as Bepridil which blocks the Na ± Ca2+ exchanger or compound 48/80 which inhibits calmodulin, also prevent the expression of the nerve growth factor receptor gene during Wallerian degenerationin vitro. Treatment of the cervical sympathetic trunk with Bepridil leads to loss of the nerve growth factor receptor immunoreactivity which is normally present. The results indicate that Ca2+ may play a role in the expression of the nerve growth factor receptor gene during Wallerian degeneration and provide some indication that this effect may be directly on the Schwann cell rather than operating indirectly via the axon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01181486
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Expression of Po mRNA in myelinating Schwann cells is related to fibre size (1991)
    Springer
    Journal of neurocytology 20 (1991), S. 396-403 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study examines whether there is a relationship between the abundance of expression for Po mRNA in myelinated Schwann cells and fibre diameter. Individual teased sciatic nerve fibres from young adult rats were hybridized with radiolabelled probe for Po mRNA which is expressed in the perinuclear cytoplasm of the mid-internode. Signal intensity was measured as optical density of the developed autoradiograms. A highly significant positive linear correlation was present between signal intensity and fibre diameter. In a companion study, individual fibres were mounted in Araldite resin and transversely serially sectioned at 4 μm for autoradiography. Grain densities were determined for fibres of different diameters. Again, larger diameter fibres were associated with higher grain densities. The results indicate that the abundance of Po mRNA expressed by a myelin-producing Schwann cell is related to fibre diameter with axonal size probably being the critical determinant. Axons may regulate Po expression through the number of signalling molecules exposed on or released from the axolemma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01355536
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The transport and sorption of water in polyethersulphone, polysulphone, and polyethersulphone/phenoxy blends (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 2479-2485 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Sorption isotherms and steady state permeabilities for water have been measured at 40°C for polyethersulphone, polysulphone, phenoxy polymer, and polyethersulphone-phenoxy blends. The pressure dependence of the permeability in all cases was weak and the permeability of phenoxy polymer is an order of magnitude smaller than that of polyethersulphone and polysulphone. The dependence of the permeability on blend composition is compared with an empirical expression often used to describe transport in miscible blends. The effect of phase separation on the permeability is studied briefly.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410946
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    Paper (German National Licenses)
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