| 1. |
- Edström, Anders, et al.
(författare)
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Regeneration in vitro of the adult frog sciatic sensory axons
- 1990
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Ingår i: Restorative Neurology and Neuroscience. - 0922-6028. ; 1:3-4, s. 261-266
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Tidskriftsartikel (refereegranskat)abstract
- The adult frog sciatic nerve offers several advantages as an in vitro model to study nerve regeneration. The nerve with the attached dorsal root ganglia can easily be isolated and incubated in a culture medium for several days. If the nerve is subjected to a crush immediately after dissection there is a delay of 3.4 days after which the sensory axons start to regenerate into the distal nerve stump at a constant rate of about 1.1 mm · day−1 in serum-containing and 1.0 mm · day−1 in serum-free medium. Serum-free cultures may be used in future studies to examine the effect of various neurotrophic factors. The existence of an accurate method for examining the outgrowth distance, based on axonal transport of labelled proteins, contributes to the attractiveness of the model. A compartmental culture system permits separate exposure of the ganglia and the nerve to different agents. Taking advantage of this, pharmacological studies suggest that Schwann cells produce signals, dependent on newly transcribed RNA, which transform the preparation into a growth state. The present model system offers favourable conditions to learn more about the early events and also the subsequent steps of the regeneration process.
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| 2. |
- Remgård, Pär, et al.
(författare)
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A Fast Axonally Transported Protein of the Frog Sciatic Sensory Axons Undergoes Similar Qualitative Changes During Regeneration In Vitro and In Vivo
- 1991
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Ingår i: Journal of Neurochemistry. - : Wiley. - 0022-3042 .- 1471-4159. ; 57:6, s. 1907-1912
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Tidskriftsartikel (refereegranskat)abstract
- The adult frog sciatic sensory neurons have been shown to regenerate in vitro. If a crush injury is made at the beginning of culture, regeneration starts after 3.4 days and proceeds at a rate of ∼0.8 mm/day for several days. Two‐dimensional gel electrophoresis was used to study the patterns of radiolabeled, fast axonally transported proteins during the first 7 days of regeneration. Interest was focused on one protein, referred to as rrp31 (regeneration‐related protein 31), which changed in apparent pl from 4.9 to 5.3 when the outgrowth of new fibers started. The change was noticeable 3 days after injury and became prominent during day 5 of culturing. By day 7 the pl changed again, this time toward the original value. The in vitro results were supported by experiments in vivo. In this case the change occurred earlier, with a peak only 3 days after injury, after which the pl decreased. If adenosine at 1 mM was included in the culturing medium, the outgrowth of sensory axons was inhibited in a nontoxic way, and the pl changes of rrp31 were prevented. The temporal nature of the pl changes suggests a role for rrp31 in the initiation of the regeneration process.
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| 3. |
- Remgård, Pär, et al.
(författare)
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Calmodulin and In Vitro Regenerating Frog Sciatic Nerves : Release and Extracellular Effects
- 1995
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Ingår i: European Journal of Neuroscience. - : Wiley. - 0953-816X .- 1460-9568. ; 7:6, s. 1386-1392
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Tidskriftsartikel (refereegranskat)abstract
- Although calmodulin (CaM) is commonly considered to be an intracellular protein, it has been suggested lately that it is released and exerts functions extracellularly. In the present investigation this was studied in in vitro regenerating adult frog (Rana temporaria) sciatic nerves. Using a multi‐compartment incubation chamber, the non‐neuronal cells in the outgrowth region of such nerves were radiolabelled with amino acid precursors. Based on immunological criteria, these cells were shown to release CaM. When the nerves were treated with CaM, both the outgrowth of sensory axons and the injury‐induced proliferation of non‐neuronal cells were partially inhibited. The inhibitory effects occurred even when the incubation medium contained as little as 30 pM CaM. Furthermore, treatment with anti‐CaM antibodies resulted in reduced outgrowth, which suggested that during normal conditions extracellular CaM is kept at an optimal concentration. Finally, conditioned medium was found to contain several CaM‐binding proteins. The present findings may reflect an earlier unknown function of extracellular CaM in controlling various growth mechanisms in integrated tissues.
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| 4. |
- Remgård, Pär, et al.
(författare)
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Growth cones of regenerating adult sciatic sensory axons release axonally transported proteins
- 1992
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Ingår i: Brain Research. - 0006-8993. ; 572:1-2, s. 139-145
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Tidskriftsartikel (refereegranskat)abstract
- Labelled, rapidly transported axonal proteins were shown to be released frog adult frog sciatic sensory neurons, regenerating in vitro after a crush injury. The spatial distribution of the transported, released proteins could accurately be resolved by culturing the nerve on nitrocellulose paper, which trapped the released proteins. The release was located to the crush and to the entire outgrowth region. When regeneration was inhibited by adenosine, the release was limited to the crush site, implying that the release was linked to the growing axons. Other experiments suggested that the release emanated from growth cones. Furthermore, two-dimensional electrophoretical analysis of both fast axonally transported and of released proteins showed that the represented a selection of the transported protein species.
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| 5. |
- Remgård, Pär, et al.
(författare)
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Regenerating Peripheral Axons Transport and Release Low‐Molecular‐Mass Materials In Vitro
- 1994
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Ingår i: Journal of Neurochemistry. - : Wiley. - 0022-3042. ; 62:4, s. 1302-1309
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: The release of radiolabeled material from regenerating frog sciatic nerves was studied using a multicom‐ partment chamber, in which the ganglia and the outgrowth region, respectively, were separated from the rest of the nerve. The nerves were incubated with radioactive amino acids in the ganglionic compartment, and the material transported to and released at the outgrowth region was collected and analyzed. Approximately 10% of the transported radioactivity was released over a 24‐h incubation period. Of the released materials, 84% had a molecular mass of < 1,000 daltons [the low‐molecular‐mass (LM) fraction] as determined by exclusion chromatography. The presence of LM material could not be explained by leakage, nor was it due to intracellular or extracellular degradation of radiolabeled, transported proteins. It was reduced by cold and was shown by the use of vinblastine to be dependent on axonal transport. According to TLC, both the original precursor and metabolites thereof could be detected among the released LM material. The present results demonstrate the existence of a transport system for LM material in peripheral axons. The preferential release of LM over high‐molecular‐mass material at the outgrowth region suggests that it could serve specific functions during regeneration.
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