| 1. |
- Edbladh, Magnus, et al.
(författare)
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Early regeneration in vitro of adult mouse sciatic axons is dependent on local protein synthesis but may not involve neurotrophins
- 1994
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Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940. ; 168:1-2, s. 37-40
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Tidskriftsartikel (refereegranskat)abstract
- The sensory axons of the adult mouse sciatic nerve were shown to regenerate after a local test crush lesion in vitro in a serum-free medium. The average outgrowth distance of the leading axons after culturing for 3 days was 2.8 ± 0.1 mm, which was shorter than in vivo (3.8 ± 0.2 mm). With the use of a compartmentalised culture system we could show that regeneration was partially dependent on local protein synthesis in the injury region. The initial stages of regeneration did not seem to involve neurotrophins since both K252a and K252b, selective and nontoxic inhibitors of the neurotrophin actions, failed to inhibit axonal growth. The present in vitro model system offers favourable conditions to investigate the early events of the regeneration process in an adult mammalian peripheral nerve.
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| 2. |
- Edbladh, M., et al.
(författare)
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Insulin and IGF-II, but not IGF-I, stimulate the in vitro regeneration of adult frog sciatic sensory axons
- 1994
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 641:1, s. 76-82
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Tidskriftsartikel (refereegranskat)abstract
- We used the in vitro regenerating frog sciatic nerve to look for effects of insulin and insulin-like growth factors I and II (IGF-I, IGF-II) on regeneration of sensory axons and on injury induced support cell proliferation in the outgrowth region. In nerves cultured for 11 days, a physiological dose (10 ng/ml, ≈ nM) of insulin or IGF-II increased ganglionic protein synthesis (by 20% and 50%, respectively) as well as the level of newly formed, radiolabelled axonal material distal to a crush injury (both by 80%), compared to untreated, paired controls. In addition, insulin increased the outgrowth distance of the furthest regenerating sensory axons by 10%. The preparation was particularly sensitive to insulin during the first 5 days of culturing. Furthermore, both insulin and IGF-II were found to inhibit proliferation of support cells in the outgrowth region in a manner suggesting effects via their individual receptors. The inhibition, about 30%, was observable after 4 but not 11 days in culture. It is not clear if this reflects a stimulated differentiation of some cells. By contrast, IGF-I lacked effects on both regeneration and proliferation. In conclusion, the results suggest that insulin and IGF-II are involved in the regulation of peripheral nerve regeneration.
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| 3. |
- Edström, Anders, et al.
(författare)
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Adenosine inhibition of the regeneration in vitro of adult frog sciatic sensory axons
- 1992
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Ingår i: Brain Research. - 0006-8993. ; 570:1-2, s. 35-41
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Tidskriftsartikel (refereegranskat)abstract
- The sensory axons of the adult frog sciatic nerve have earlier been shown to regenerate in vitro. If a local test crush is made at the initiation of culturing, regeneration starts after 3.4 days and proceeds at a rate of about 0.8-0.9 mm/day for several days. In the present experiments regeneration was inhibited by adenosine in a reversible and dose-dependent fashion. Similarly, both an adenosine analogue, 2-chloroadenosine (2-CA), and a non-hydrolyzable ATP analogue, AMP-PNP, reduced the outgrowth of sensory axons. The effect of adenosine was partially antagonized by theophylline at a critical concentration. Using a compartmental system, it could clearly be shown that adenosine exerted its effects at the outgrowth region. Adenosine, 2-CA, and AMP-PNP were also found to inhibit the proliferation of Schwann cells in the regenerating nerve. Various experiments showed that the latter can not explain the outgrowth inhibitory effects, which could be mediated by adenosine receptors associated with the elongating axons.
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| 4. |
- 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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| 5. |
- Ekström, Per, et al.
(författare)
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A calmodulin inhibitor with high specificity, compound 48/80, inhibits axonal transport in frog nerves without disruption of axonal microtubules.
- 1991
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Ingår i: Acta physiologica Scandinavica. - 0001-6772. ; 142:2, s. 181-9
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Tidskriftsartikel (refereegranskat)abstract
- The calmodulin inhibitor compound 48/80 has previously been shown to arrest axonal transport in vitro in the regenerating frog sciatic nerve. The inhibition was limited to the outgrowth region of nerves, which had been allowed to regenerate in vivo for 6 days after a crush lesion, before they were incubated with or without drugs in vitro overnight. The effects of compound 48/80 on the regenerating nerve were further investigated. A concentration of compound 48/80 (50 micrograms ml-1), which effectively inhibits axonal transport, did not cause observable changes of the microtubules of regenerating axons in the outgrowth region as judged by electron microscopy. Furthermore, it was shown that also a lower concentration (25 micrograms ml-1) inhibited axonal transport. As a measure of possible metabolic effects, the level of ATP was assessed in the regenerating nerve after exposure to compound 48/80. Compound 48/80 at 25 micrograms ml-1 did not change the level of ATP in the nerve. The assembly of bovine brain microtubule proteins in a cell-free system was unaffected by 25 micrograms ml-1 of compound 48/80 and slightly inhibited by 50 micrograms ml-1. At higher concentrations (greater than 100 micrograms ml-1) assembly of microtubules appeared stimulated, and microtubule spirals as well as closely aligned microtubules could be seen. These effects appeared to be unrelated to the transport effects. The present results indicate that compound 48/80 arrests axonal transport via mechanisms other than destruction of axonal microtubules or interference with the energy metabolism. It is possible that these mechanisms involve inhibition of calmodulin-regulated events essential to the transport.
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| 6. |
- Ekström, Per A R
(författare)
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Insulin stimulates ganglionic protein synthesis and reduces thymidine incorporation in support cells of the in vitro regenerating adult frog sciatic sensory neurons
- 1991
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Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940. ; 132:2, s. 183-186
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Tidskriftsartikel (refereegranskat)abstract
- Insulin was tested for effects on crush injured, in vitro regenerating, adult frog sciatic sensory axons. A wide range of insulin concentrations (0.01-10 μg × ml-1) was found to stimulate incorporation of radioactive leucine into ganglionic protein by 50-80%. without affecting the regeneration distance. Simultaneously insulin inhibited the proliferation of the support cells at the crush region by 30%, as measured by thymidine incorporation. Experiments using compartmentalized culture dishes indicated that the proliferation inhibitory effect could be indirect and mediated by the neuronal cells. The results suggest that insulin influences the metabolism of adult peripheral neuronal cell bodies. The stimulated nerve cells could in turn affect the proliferation of support cells in the nerve trunk.
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| 7. |
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| 8. |
- Ekström, Per, et al.
(författare)
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Effects of protein kinase inhibitors on regeneration in vitro of adult frog sciatic sensory axons
- 1992
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Ingår i: Journal of Neuroscience Research. - : Wiley. - 0360-4012 .- 1097-4547. ; 31:3, s. 462-469
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Tidskriftsartikel (refereegranskat)abstract
- The effects of protein kinase inhibitors on regeneration in vitro of adult frog sciatic sensory axons were tested. Regeneration of crush‐injured nerves for 8 days in serum‐free medium was inhibited by staurosporine (100 nM) and H‐7 (100 μM), which are both known to inhibit protein kinase C. With the use of a compartmented culture system it could be shown that H‐7 exerted both local (outgrowth region) and central (ganglia) effects, the latter being more pronounced. The local effects could be due to reduction of Schwann cell proliferation by H‐7. Immunohisto‐chemistry demonstrated the presence of protein kinase C in neuronal cell bodies but not in axonal processes. Proliferation of Schwann cells was accompanied by increased protein kinase C immunoreactivity at the site of injury. H‐7 caused a selective inhibition in the incorporation of radioactive phosphate into one 74 kDa protein of both ganglia and nerve but also a more general decrease in protein labelling. The results show that protein phosphorylations, possibly mediated by protein kinase C, are involved in regeneration‐related mechanisms operating at both local and central levels in the adult frog sciatic sensory axons.
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| 9. |
- Holmqvist, Bo I., et al.
(författare)
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Nitric oxide synthase in the brain of a teleost
- 1994
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Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940. ; 171:1-2, s. 205-208
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Tidskriftsartikel (refereegranskat)abstract
- The presence and distribution of the nitric oxide (NO) converting enzyme, NO synthase (NOS), was investigated in the brain of a teleost, the Atlantic salmon. Both NOS immunoreactive and NADPH diaphorase positive, non-neuronal and neuronal cell bodies, fibers and putative nerve terminals were identified throughout the brain. Even so, the staining was not identical in all regions. NO, synthesized by NOS-like enzymes, may play an important role in a diversity of cellular mechanisms in the brain of the salmon, including in neural systems related to olfactory, visual, hypophysiotrophic, viscero-sensoric and motor functions.
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| 10. |
- Käll, Per-Olov, et al.
(författare)
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Phase Composition and Mechanical Properties of HIP-Sintered Y/Nd-Sialon Ceramics
- 1990
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Ingår i: Proc. 11th Risö Internat. Symp. on Metallurgy and Materials Science. ; , s. 383-388
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Konferensbidrag (refereegranskat)abstract
- Sialon ceramics were hot isostatic pressed (HIP) at 1820 K, 2050 K and 2100 K using mixtures of Y2O3/Nd2O3 as sintering aids. The overall sialon compositions were selected to obtain either pure beta sialons or mixed alpha-beta sialons with different alpha/beta ratios. The ratio of the Y2O3/Nd2O3 additions was varied from pure yttria to pure neodymia, and the materials have been characterised with respect to phase content, microstructure, chemical composition, Vickers hardness and fracture toughness. The results are compared with those for the same compositions pressureless sintered.
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