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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 8 (1996), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 13 (2001), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 195 (1962), S. 509-509 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We have now carried out experiments to determine some of the structural changes accompanying these functional alterations. After cutting all the tendons around the ankle joint, the animals were killed at varying intervals after the operation, and cross-sections of the soleus and peroneus longus ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 360 (1992), S. 216-216 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [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 ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 419 (1991), S. 319-326 
    ISSN: 1432-2013
    Keywords: Muscle ; Overload ; Activity ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rat extensor digitorum longus (EDL) muscles were overloaded by removal of the synergist tibialis anterior (TA). The weight of the overloaded muscle was increased 15 days after the initial operation and remained higher throughout the period studied (153 days). The times to peak twitch tension and half relaxation remained unaltered, but the twitch and tetanic tensions developed by the overloaded EDL muscles increased. The overloaded EDL muscles became significantly more fatigue resistant. In a separate group of animals the overloaded EDL muscle was also chronically stimulated at 10 Hz. The additional stimulation altered the response of the EDL to overload in that the time to peak twitch tension of the muscle was slightly prolonged. There was no increase in twitch or tetanic tension in spite of the increase in muscle weight, but the electrical stimulation led to a further increase in fatigue resistance above that seen in overloaded muscles. The histochemical and immunocytochemical examination of the muscle revealed that there was a moderate increase in succinate dehydrogenase activity in the muscles overloaded only, but a considerable increase in those overloaded muscles that were also stimulated. There was no obvious change in the number of muscle fibres that reacted with an antibody to slow myosin in either overloaded only or overloaded and stimulated EDL muscles. Thus the addition of continuous activity to overload induced a slowing of contraction and prevented the increase of force usually induced by overload.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2013
    Keywords: Rat ; Skeletal muscle ; Development ; Ionic conductances ; Denervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 59 (1972), S. 469-470 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2013
    Keywords: Capillary density ; Slow and fast muscles ; Chronic stimulation ; Fibre diameters ; Succinic dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary When rabbit fast muscles were chronically stimulated at a frequency naturally occurring in nerves to slow muscles (10 Hz), there was a transformation towards a slow muscle type such as an increase of capillary density, increased activity of the oxidative enzyme, succinic dehydrogenase, and a decrease of muscle fibre diameters. After 28 days the intensity and distribution of SDH and the capillary density were similar to those of soleus. The increases in capillary density preceded the changes in activity of SDH; there was a significantly greater capillary/muscle fibre ratio and number of capillaries/mm2 in muscles stimulated for only 4 days at which time no change could be detected in SDH. These changes were induced by slow frequency stimulation only, and not by an overall increase of activity. Stimulation of fast muscles for 4 days at a higher frequency naturally occurring in the nerves to fast muscles (short bursts of tetani), with the same total number of stimuli as that used in slow frequency stimulation did not produce any changes in capillary density, activity of SDH or contraction times. No changes were observed in either fast or slow muscles stimulated with short bursts of tetani (and lower total number of impulses) up to 28 days. Activation of fast muscles at 5 Hz continuously or 10 Hz intermittently also caused an increase in capillary density. It is therefore concluded that only low frequency activation of fast muscles brings about a transformation of the muscle fibres towards a slow type and that the first noticeable change is an increase in the capillary density.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 355 (1975), S. 189-204 
    ISSN: 1432-2013
    Keywords: Cell Division ; Denervated Muscle ; Hypersensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-2013
    Keywords: Nerve-muscle interaction ; Contractile speed ; Transformation of fibre types ; Myosin light chains ; Enzyme activity pattern of energy metabolism ; Mitochondrial differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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