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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 10 (1968), S. 218-241 
    ISSN: 1432-0533
    Keywords: Myotonic dystrophy ; Sarcoplasmic masses ; Striated annulets (Ringbinden) ; Muscle fiber ; Electron microscopy ; Phase microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das Biopsiematerial von drei Patienten mit unterschiedlichen klinischen und pathologischen Stadien der myotonischen Dystrophie wurde phasenkontrast-und elektronenmikroskopisch untersucht. Beim 1. und 2. Fall waren “sarkoplasmatische Massen” und “Ringbinden” besonders zahlreich, während sie beim 3. Fall mit klinisch erheblich fortgeschrittener Muskelatrophie nur ausnahmsweise vorkamen. Elektronenmikroskopisch erschienen fast alle Elemente der Muskelfasern, zumindest an einigen Stellen, von dem atrophischen oder dystrophischen Prozeß betroffen: Myofilamente, Z-Streifen, Triaden, Kerne, Mitochondrien und Sarkolemm. Außerdem fanden sich cytoplasmatische Cysten, multilamellierte Körperchen, zahlreiche Lipofuscingranula und verschiedene andere abnorme Strukturen. Besonders kennzeichnend für die Erkrankung waren die “sarkoplasmatischen Massen”, die mit variablen Mengen von fehlorientierten Myofilamenten, aber auch von anderen Komponenten der Muskelzelle ausgefüllt waren. Die Ringbinden wurden von fehlorientierten Myofibrillen gebildet, indem sie meist kreisförmig die im Zentrum normal ausgerichteten Myofibrillen umschlossen. Einzelne Veränderungen, die bisher weder bei der myotonischen Dystrophie noch in irgendeiner anderen Muskelkrankheit nachgewiesen worden sind, konnten in leicht dystrophischen wie auch in hochgradig atrophischen Fasern nachgewiesen und identifiziert werden: Große homogene Lacunen, die sich vom sarkoplasmatischen Reticulum herleiten und eigenartige geometrische Anordnungen der terminalen Cisternen. Der Ursprung bestimmter anderer Strukturen blieb unklar. In unserem Material fanden sich keine segmentalen Nekrosen, so daß sich die Relation des dystrophischen Prozesses zur Zenkerschen Degeneration und zur Atrophie, den nach histologischen Untersuchungen wesentlichsten Befunden bei der Steinertschen Erkrankung, nicht eindeutig bestimmen ließ.
    Notes: Summary Biopsies from three patients with different clinical and pathological stages of myotonic dystrophy were studied by phase and electron microscopy. Large sarcoplasmic masses and spiral annulets were prominent in Cases 1 and 2 while in Case 3, featured clinically by atrophic weakness, they were infrequent. In the latter the residual fibers were either large and dystrophic or small and atrophic. Electron microscopically, nearly all components of the muscle cell, in places, were involved in the dystrophic or atrophic process, such as myofilaments, Z discs, triads, nucleic, mitochondria, and the sarcolemma. In addition, cytoplasmic cysts, multilammellated bodies, and lipofuscin granules were observed. The most characteristic feature of the disease were sarcoplasmic masses, filled with varying amounts of disoriented myofilaments and other sarcoplasmic components. Disoriented myofibrils often encircled the remaining core of normal myofibrils, thus forming the striated annulets (Ringbinden). Several other abnormalities, not previously reported in myotonic dystrophy or any other myopathy, were identified in slightly dystrophic as well as in severaly atrophic fibers. These were large, homogenous lacunes derived from the sarcoplasmic reticulum and peculiar geometric arrangements of terminal cisternae. The origin of some other structures remains obscure. The relation of the dystrophic process to segmental degeneration and atrophy, the principal histologic findings in Steinert's disease, is unsettled since segmental necrosis was not observed in our samples for phase and electron microscopy.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Natural hazards 4 (1991), S. 389-419 
    ISSN: 1573-0840
    Keywords: Earthquakes ; historical seismicity ; Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract We have re-examined those earthquakes in Africa south of 20°N, in the period 1900–1930, that appear from instrumental or macroseismic evidence to have a magnitude of 5 3/4 or greater. We identify more than 50 such events, about twice as many as listed by Gutenberg and Richter (1954). We find that the combined use of early instrumental readings and macroseismic information gleaned from previously untapped sources gives the best control of location. Instrumental relocation is difficult because of the lack of stations in Africa and the very uneven global distribution. For the low-gain, medium-period instruments then in use, the best control often comes from using the maximum Airy phase of surface waves. Similarly, there is a lack of sources of macroseismic information, and the simple building practice makes it difficult to assess intensity. We have recalculated magnitude Ms uniformly using the Prague formula. We discuss these problems and show that it is likely that our list is complete only down to magnitude about 6, and that the seismic record for Africa before this century will probably remain incomplete for events of all magnitudes. Of the 54 events in our list 20 are between magnitude 6 and 7, and the largest is the Rukwa earthquake of 1910 in Tanzania (Ms 7.4). The only other African event known to rival it in size is that in southern Sudan on 20 May 1990 (Ms 7.2).
    Type of Medium: Electronic Resource
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