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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 13 (2001), S. 0 
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The effect of riluzole on the survival of injured motoneurons was studied. The L4 ventral root was avulsed and reimplanted into the spinal cord. Immediately after the operation, 4 animals were treated with riluzole for 3 weeks while another 4 animals received no treatment after the operation. Three months later the fluorescent dyes, Fast Blue and Diamidino Yellow, were applied to the cut ventral ramus of the L4 spinal nerve, for retrograde labelling of neurons. Three days later, the spinal cords were processed to reveal the retrograde-labelled cells. In untreated animals, there were 20 ± 2.1 labelled neurons (± SEM), while in animals treated with riluzole there were 723 ± 26. Thus, treatment with riluzole dramatically enhanced the survival of injured motoneurons. In another series of experiments, after avulsion of the L4 ventral root and its reinsertion, embryonic spinal cord pieces were grafted into the host cord. Five animals received riluzole treatment and 4 were left untreated. In the untreated animals, 125 ± 5.1 retrograde-labelled cells of both graft and host origin were detected. In rats treated with riluzole, 645 ± 35.7 retrograde-labelled cells were seen and almost all of these were of host origin. Thus, treatment with riluzole enhanced the survival of injured host motoneurons, and by doing so, (i) reduced the ability of grafted neurons to extend their axons into the reimplanted L4 ventral root, and (ii) reduced the survival of the grafted cells.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 8 (1996), S. 0 
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Loss of motoneurons results in a decrease in force production by skeletal muscles and paralysis. Although it has been shown that missing motoneurons of rats can be replaced by embryonic homotopic neurons, attempts to guide their axons to their target muscles that have lost their innervation have been unsuccessful. In this study attempts were made to guide axons from grafted embryonic motoneurons to their target via a reimplanted ventral root. Adult hosts that received an embryonic graft prelabelled with 5-bromo-2′-deoxyuridine had their L4 ventral root avulsed and reimplanted into the spinal cord. Three to six months later, neurons that had their axons in the L4 ventral ramus were retrogradely labelled with fast blue and diamidino yellow. In five animals that had received an embryonic graft 116 ± 16 cells were retrogradely labelled, and of these at least 15% were of graft origin, since they were positive for 5-bromo-2′-deoxyuridine. In five animals that had their L4 ventral root reimplanted but did not receive a graft, only 12 ± 1.3 cells were retrogradely labelled. However, meaningful functional recovery could be achieved only if the regenerating axons of embryonic motoneurons found in the L4 ventral ramus were able to reverse the loss of force of muscles that had lost their innervation. This study shows that axons of embryonic motoneurons grafted into an adult rat spinal cord, as well as some axons of host origin, can be guided to denervated hindlimb muscles via reimplanted lumbar ventral roots. In normal rats ∼30 motor axons innervated the extensor digitorurn longus and 60 innervated the tibialis anterior via the L4 ventral root. In rats that did not receive a graft only 3.7 ± 1.2 axons reached the extensor digitorum longus and 3.5 ± 0.4 reached the tibialis anterior muscle via the implanted L4 ventral root. In animals that had an embryonic graft, 7.6 ± 0.5 axons innervated the extensor digitorum longus and 8.5 ± 0.5 reached the tibialis anterior muscle via the implanted root. In rats without a transplant the maximum tetanic tension elicited by stimulating the implanted L4 root was 16 ± 7 g for the extensor digitorum longus and 53 ± 36 g for the tibialis anterior muscle, whereas the corresponding muscles in animals that had an embryonic graft developed 82 ± 16 and 281 ± 95 g respectively. Thus it appears that the grafted motoneurons contributed to the innervation and functional recovery of the denervated muscles.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-2013
    Schlagwort(e): Nerve-muscle interaction ; Contractile speed ; Transformation of fibre types ; Myosin light chains ; Enzyme activity pattern of energy metabolism ; Mitochondrial differentiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Fast-twitch tibialis anterior and extensor digitorum longus rabbit muscles were subjected to long-term intermittent (8 h daily) or continuous (24 h daily) indirect stimulation with a frequency pattern resembling that of a slow motoneuron. Increases in time to peak of isometric twitch contraction were observed without parallel changes in the pattern of myosin light chains or alterations in the distribution of slow and fast fibres as discernible by the histochemical ATPase reaction. However, changes in the fibre population and in the myosin light chain pattern were observed after intermittent stimulation periods exceeding 40 days or continuous stimulation periods longer than 20 days. Under these conditions even higher increases were found in contraction time. In one animal a complete change in fibre population was observed. In this case myosin light chains of the slow (LCS1, LCS2) and of the fast type (LCf1) were obviously synthetized simultaneously within the same fibre. Early changes in the enzyme activity pattern of energy metabolism indicated a conversion of the fibres including their mitochondrial population. These changes and the earlier reported changes in the sarcoplasmic reticulum are probably responsible for the early changes in contractile properties which occur before the transformation of the myosin.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 360 (1975), S. 349-364 
    ISSN: 1432-2013
    Schlagwort(e): Chemosensitivity ; Developing muscle ; Endplate formation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. The sensitivity to acetylcholine (ACh) of the fast posterior latissimus dorsi (PLD) and slow anterior latissimus dorsi (ALD) during embryonic development was studied and compared. The sensitivities were expressed as a ratio of the maximal tetanic tension and tension developed in response to ACh. 2. Up to the 17th day of incubation both muscles are sensitive to ACh to a similar extent; at the 18th day the sensitivity of the PLD muscle decreases and continues to do so until hatching and thereafter. 3. Since the decrease in sensitivity of PLD muscles takes place a few days after innervation, it is suggested that this is caused by activity of the motor nerve. To test this curare (dTc) and hemicholinium (HC-3), drugs that interfere with neuromuscular transmission, were injected into the yolk sac of the embryos when nervemuscle connections are usually established. In the curare and HC-3 treated embryos the desensitization of the PLD muscles did not take place. 4. The distribution of endplates on PLD muscles from drug treated 20–21 day old embryos was compared to that of untreated controls. Whereas control PLD muscles have only one band of endplates, muscles from curarized embryos and HC-3 treated embryos have several bands of endplates, and many muscle fibres with multiple innervation were found. 5. It is suggested that nerve fibres which make connections with PLD muscle fibres bring about a decline in chemosensitivity by releasing more transmitter, and thereby prevent further nerve muscle connections from being made along the same muscle fibre.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 355 (1975), S. 189-204 
    ISSN: 1432-2013
    Schlagwort(e): Cell Division ; Denervated Muscle ; Hypersensitivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. It was found that in 3 day denervated soleus and EDL muscles nuclear division takes place. This can be stopped by administration of either 5-fluoro-uracil or vincristine. 2. The increased sensitivity to acetylcholine following denervation developed at a time when rapid cell division takes place. Both 5-fluoro-uracil and vincristine prevent the development of denervation hypersensitivity both in soleus and EDL muscles. 3. Muscle injury causes some cell division locally, but some phagocytic cells that infiltrate the damaged muscle appear to be blood-borne as their appearance within the muscle is not entirely prevented by either 5-fluoro-uracil or vincristine. Correspondingly the development of increased sensitivity that follows muscle injury is only partly prevented by administration of cytotoxic drugs. 4. It is suggested that the presence of dividing cells is causally related to the development of denervation hypersensitivity.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-2013
    Schlagwort(e): Muscle differentiation ; Contractile properties ; Myosin light chains ; Two dimensional gel electrophoresis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract 1. The contractile speeds and tetanus/twitch ratios of the slow anterior latissiumus dorsi (ALD) and fast posterior, latissimus dorsi (PLD) muscles were studied during embryonic development and correlated with the type of myosin light chains present in these muscles as studied by one and two dimensional polyacrylamide gel electrophoresis. 2. At a time when the contractions of PLD were slow, i.e. in 15 day old embryos, the myosin light chains in this muscle were of the fast type. The slow contraction of this muscle may be due to incomplete and slow activation of the contractile elements. The tetanus/twich ratio of muscles from 15 day old embryos is low and increases sharply with age. This increase could be due to the maturation of the internal membrane system, and occurs at about the same time as the increase in the speed of contraction. 3. ALD muscles contract slowly during all stages of development, although their tetanus/twitch ratio also increases with age. At 13 days they contain a mixture of fast and slow type myosin light chains and with increasing age the proportion of the slow type myosin light chains increases at the expense of the fast type. The slow time course of contraction of ALD is consistent with the presence of slow type myosin light chains. 4. The possibility that the synthesis of the slow type myosin light chains in ALD is induced by early motor activity in chick embryos is discussed.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1432-2013
    Schlagwort(e): Rat ; Skeletal muscle ; Development ; Ionic conductances ; Denervation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The development of membrane ionic conductances of rat extensor digitorum longus (EDL) muscle fibers was studiedin vitro using intracellular recordings. At 7–8 days after birth, the potassium conductance (GK) dominated the total membrane conductance while the chloride conductance (GC1) was very low. A rapid increased of GC1 towards adult values was observed after few days (12–14 day old rats), whereas GK did not decrease up to day 23. Denervation at 7–8 days after birth suppressed the maturation of the electrical parameters measured, and 15 days after the nerve crush, GC1 was just detectable. These results suggest that the maturation of the electrical properties, and in particular that of the resting chloride conductance in mammalian striated muscle fibers, occurs during the first weeks of postnatal life and is dependent on innervation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Naturwissenschaften 59 (1972), S. 469-470 
    ISSN: 1432-1904
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Inflammation research 1 (1970), S. 240-248 
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Experiments were performed on kittens to study the role of innervation on the development of the pharmacological responses of the neuromuscular junction. The importance of the nerve for the development of the differing properties of fast and slow muscles was also studied. It was confirmed that the different responses to depolarising drugs of the slow soleus and fast flexor hallucis longus muscles are not apparent during the first week of the animal's life. Even when the motor nerves to these muscles were crossed at this time the alien innervation did not affect the subsequent development of the different responses of fast and slow muscles to suxa- and decamethonium. This suggests that the different properties of the postsynaptic membrane are established very early in the animal's life and that they cannot be changed by altering the innervation. The neuromuscular junctions of these young animals are very insensitive to suxa- and decamethonium. When innervation is delayed, during the early postnatal period, the development of the high sensitivity of the neuromuscular junctions to the blocking and depolarising actions of these drugs was retarded. It is therefore concluded that the motor nerve induces the high chemosensitivity of the adult endplate region.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 360 (1992), S. 216-216 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] SIR - M. Sendtner et al. (Nature 358, 502-504; 1992) report that in a mouse mutant with progressive motor neur-onopathy, ciliary neurotrophic factor (CNTF) released by implants of genetically modified fibroblasts increases the survival of facial motor neurons and prolongs the lifespan of the ...
    Materialart: Digitale Medien
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