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  • Isoniazid  (3)
  • Reinnervation  (3)
  • 1
    ISSN: 1432-2307
    Keywords: Muscle spindle ; Elastic fibres ; Elaunin fibres ; Oxytalan fibres ; Denervation ; Reinnervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Muscle spindles in the lower lumbrical muscles of rats were studied by transmission electron microscopy following denervation with or without reinnervation. The number and total area of elastic fibres per muscle spindle increased at 3–12 months following various experimental procedures: (1) denervation and reinnervation after a single crush lesion to the sciatic nerve; (2) reinnervation after four-fold repeated crush injuries; and (3) transection and suture of the nerve. The increased number of oxytalan and elaunin fibres, the precursors of mature elastic fibres, within these muscle spindles provided further evidence for their numerical and dimensional increase. An attachment site of elastic fibres at the spindle pole was identified at the inner cells of the outer spindle capsule. The processes of these cells embraced terminating elastic fibres tightly. Attachment of elastic fibres to intrafusal muscle fibres was less conspicuous since they were not similarly embraced but were rather indistinctly, though closely, associated with the basal lamina along longitudinal surface indentations of intrafusal muscle fibres. It is concluded from this series of experiments that muscle spindles, as dynamic mechanoreceptors, maintain their elastic properties even under pathological conditions. The increase of elastic fibres following denervation and reinnervation represents an obviously meaningful reaction that may compensate for loss of tonic properties of muscle spindles without causing stiffness.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 80 (1990), S. 163-171 
    ISSN: 1432-0533
    Keywords: Neuromuscular spindle ; Reinnervation ; Nerve endings ; Autonomic innervation ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Muscle spindles from the lower lumbrical muscles of rats were studied by transmission and scanning electron microscopy following reinnervation (i) after a single sciatic nerve crush lesion and (ii) after transection and immediate epineurial suture of the sciatic nerve. In all muscle spindles, regenerated sensory or motor nerve endings were encountered 3 months after making the lesions although in the nerve-transection group, regenerated nerve endings were seen less frequently before 6 months of recovery. Abnormalities in reinnervated spindles following neurotomy comprised: (1) multiplicity of axonal sprouts (hyperinnervation), sometimes irregularly related to, although never in direct contact with, regenerated sensory nerve endings; (2) altered contact relationships between sensory nerve endings and intrafusal muscle fibers; (3) abnormal structure of nerve endings; and (4) irregular association of Schwann cell processes to regenerated sensory nerve endings. These findings indicate that reinnervation of muscle spindles following transection and suture of a peripheral nerve, i.e., after complete interruption of its continuity, in fact, occurs although the fine structural abnormalities observed are supposed to interfere with adequate functional restoration.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 16 (1970), S. 301-323 
    ISSN: 1432-0533
    Keywords: Peripheral Nerves ; Nerve Degeneration ; Endoplasmic Reticulum ; Edema ; Isoniazid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Außer den bekannten Veränderungen bei der Isoniazid (INH)-Neuropathie ließen sich bestimmte Veränderungen im peripheren Nerven nachweisen, die bisher nicht beschrieben worden sind. Dazu gehören enorme Proliferationen eines glatten endoplasmatischen Reticulums in manchen Schwannzellen und extracellulär in den Büngnerschen Bändern gelegene “Nadeln”, π- and μ-Granula. Darüber hinaus ist bei der INH-Neuropathie gelegentlich eine schwere Störung der Blutnervenschranke mit Erythrodiapedesen feststellbar, die nicht zu dem Bild der einfachen Wallerschen Degeneration gehört. Das gleiche gilt für das frühzeitige Auftreten von umfangreichen elektronendichten Strukturen in histiocytären Zellelementen des Endoneuriums. Die Unterschiede der INH-Neuropathie gegenüber anderen Formen distal akzentuierter Neuropathien vom “neuronalen” oder “dying back”-Typ und gegenüber der Wallerschen Degeneration nach Durchschneidung des Nerven werden diskutiert.
    Notes: Summary Several distinctive alterations were observed in INH-neuropathy which have not been noted so far. These were striking proliferations of an agranular endoplasmic reticulum in some Schwann cells, needle-like structures situated intra- and extracellularly within reinnervated bands of Büngner, π- and μ-granules. Furthermore, a severance of the blood nerve barrier was observed leading to erythrodiapedesis which was not seen in Wallerian degeneration. This holds true also for the very early appearance of large electrondense organelles within histiocytic cells of the endoneurium. The distinguishing features of INH-neuropathy and other distally accentuated neuropathies of the “neuronal” or “dying back” type, and of Wallerian degeneration after nerve section are discussed.
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  • 4
    ISSN: 1432-0533
    Keywords: Muscle spindle ; Denervation ; Reinnervation ; Muscle fiber atrophy ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine structure of normal, denervated, and reinnervated muscle spindles in lower lumbrical muscles of rats was studied morphometrically at time intervals ranging from 3–14 months. In control spindles, the mean transverse area of mitochondria was estimated to be more than twice as large in nuclear chain than in typical nuclear bag fibers. Following denervation, there was a severe decrease of the mean number and transverse area of mitochondria, and a moderate, but statistically significant decrease of the mean transverse area of intrafusal muscle fibers (IMFs) despite an increase of the number of IMFs. At 12–14 months of reinnervation, changes of the transverse areas of IMFs were statistically insignificant, but the mean values for the mitochondria were incompletely restored. At 4×3 months, after fourfold repeated crush injuries to the nerve, most of the values estimated (transverse area of mitochondria; number, shape, and transverse area of IMFs and nuclei) tended to approach those in denervated rather than in reinnervated IMFs. The differences of the reactions of intra- and extrafusal muscle fibers following complete motor and sensory denervation appeared to be in accordance with their normal dimensional dissimilarities.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 16 (1970), S. 324-341 
    ISSN: 1432-0533
    Keywords: Spinal Cord ; Spinal Ganglia ; Neuromuscular Spindles ; Mitochondria ; Isoniazid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Entgegen anderslautender Angaben in der Literatur werden bei der INH-Neuropathie auch die sensorischen Nervenendigungen in den Muskelspindeln betroffen. Die Veränderungen bestehen in einem Verlust der synaptischen Vesikel, in Mitochondrienschwellungen und-Verdichtungserscheinungen, in terminalen Axonfragmentationen und Reaktionen der zugehörigen intrafusalen Muskelfasern. Außerdem lassen sich schon in frühesten Stadium der INH-Neuropathie, am 4. Tag nach Beginn der INH-Applikation, Veränderungen in den lumbosacralen Spinalganglien und im Rückenmark nachweisen. Die Veränderungen in den Perikaryen gleichen denen bei der retrograden Zellveränderung weitgehend. Über die Spezifität der Alterationen an den sensorischen Nervenendigungen ist vorest keine sichere Aussage möglich, da vergleichbare Untersuchungen über pathologisch veränderte Muskelspindeln, insbesondere nach der einfachen Durchschneidung des Nerven, bisher fehlen.
    Notes: Summary In INH-neuropathy sensory nerve endings of distal muscle spindles may be severely altered. The changes are characterized by a disappearance of synaptic vesicles, mitochondrial swelling or condensation, fragmentation of axon terminals and reactions of the corresponding intrafusal muscle fibers. Also, occasional alterations in lumbosacral spinal ganglia and spinal cord were seen occurring already in the initial stage of INH-neuropathy at the 4th day after the beginning of INH application. The perikaryal changes resemble those of the retrograde cell reaction. Any specificness of the alterations seen in the sensory endings of muscle spindles cannot be ruled out at the present time since there are no comparable fine structural studies of pathological alterations in muscle spindles after simple nerve section or other nerve lesions.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 15 (1970), S. 156-175 
    ISSN: 1432-0533
    Keywords: Peripheral Nerve ; Nerve Degeneration ; Axon ; Mitochondria ; Isoniazid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Im N. ischiadicus der Ratte kommen etwa doppelt so viele marklose als markhaltige Nervenfasern vor. Das normale zahlenmäßige Verhältnis dieser beiden Fasertypen schwankt in weiten Grenzen. Schon im ungeschädigten Nerven lassen sich bereits an einzelnen marklosen Nervenfasern verschiedenartige regressive Veränderungen wie Strukturverlust und perlschnurförmige Auftreibungen nachweisen; sie sind in der Regel von akuten, toxisch bedingten Veränderungen durch das Fehlen charakteristischer Schwann-Zellreaktionen zu differenzieren. Bei der INH-Neuropathie degenerieren anfangs im Verhältnis zu den markhaltigen nur wenige marklose Nervenfasern. Einige marklose Axone können unregelmäßig konturiert, geschwollen oder geschrumpft erscheinen; dabei lösen sich die Tubuli und Filamente auf; in manchen Fällen verdichtet sich ausch das Axolemm. Die Axonveränderungen werden von Störungen der normalen Axon-Schwann-Zellrelation begleitet. In den Anfangsstadien können manche Schwann-Zellen hochgradig deformiert sein; später verlieren sie ihre Oberflächendifferenzierung und runden sich (auf dem Querschnitt) ab. In der Regel zeigen die marklosen Nervenfasern bei der INH-Neuropathie die gleichen Veränderungen und Störungen der Axon-Schwann-Zellrelation wie bei der Wallerschen Degeneration. Extreme prolapsartige Verformungen von Axonen und Schwann-Zellen sowie mitochondriale Granula haben wir jedoch nur bei der INH-Neuropathie, nicht aber bei der Wallerschen Degeneration beobachtet.
    Notes: Summary In sciatic nerves of rats, there are more than twice as much unmyelinated than myelinated axons. Their ratio varies in a wide range from one area to the other. Some regressive changes are seen already in unmyelinated axons of normal controls (loss of structural components, axonal beading). Usually, these alterations can be distinguished from early experimental lesions by the lack of characteristic Schwann cell reactions. In the beginning of INH-neuropathy, fewer unmyelinated than myelinated nerve fibers are degenerating. Some of the unmyelinated axons may become irregularily folded, swollen, or shrunken while there is a progressive loss of tubules, filaments, normal mitochondria, and sometimes an increase in the thickness of the axolemma. The axonal changes are accompanied by a disturbance of the normal axon-Schwann cell relation. Initially, some Schwann cells may become extremely irregular; later they lose their surface differentiation while their cross sectional contour becomes rather rounded. In general, unmyelinated axons in INH-neuropathy show similar alterations and disturbances of the axon-Schwann cell relation as seen in Wallerian degeneration. Yet extremely deformed unmyelinated nerve fibers, axons as well as Schwann cells, and mitochondrial granules were only observed in INH-neuropathy.
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