| 1. |
- Lundborg, G, et al.
(författare)
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Can sensory and motor collateral sprouting be induced from intact peripheral nerve by end-to-side anastomosis?
- 1994
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Ingår i: Journal of Hand Surgery: European Volume. - : SAGE Publications. - 0266-7681. ; 19:3, s. 82-277
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Tidskriftsartikel (refereegranskat)abstract
- The possibility that collateral sprouting could occur from intact axons in an undamaged sciatic nerve was studied in the rat by suturing either a 7-day predegenerated or a fresh nerve segment in an end-to-side fashion to the sciatic nerve proper. Following a 14- or 35-day recovery period, the pinch reflex test was performed on the transplanted segment to demonstrate the presence of sensory axons. The majority of cases, using a predegenerated nerve segment but not a fresh segment, responded positively. Neurofilament staining and histological examination confirmed the presence of axons in the attached nerve segment. In another series of experiments, the proximal peroneal fascicle was ligated and cut. Following a 7-day predegeneration period the distal stump was sutured end-to-side to the ipsilateral tibial fascicle. After 90 days, stimulation of the tibial nerve proximal to the attached site induced substantial contraction in both the native gastrocnemius muscle and the foreign tibialis anterior muscle. These findings suggest that collateral sprouting may occur from intact axons, perhaps induced by factors emanating from the attached nerve segment, and subsequently make functional peripheral connections.
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| 2. |
- Lundborg, G, et al.
(författare)
-
Trophism, tropism, and specificity in nerve regeneration
- 1994
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Ingår i: Journal of Reconstructive Microsurgery. - : Georg Thieme Verlag KG. - 0743-684X .- 1098-8947. ; 10:5, s. 54-345
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Tidskriftsartikel (refereegranskat)abstract
- Target-derived neurotrophic factors are of basic importance for survival of neurons. In the normal state, such neurotrophic factors, synthesized by the target tissues, are taken up by nerve terminals and transported by retrograde axonal transport in axons to the nerve-cell bodies to maintain their viability. After nerve injury, neurotrophic factors are synthesized by non-neuronal cells (Schwann cells and fibroblasts) in the nerve trunk, thereby supporting the outgrowth of axons. Neurite-outgrowth-promoting factors on cell surfaces (cell adhesion molecules, "recognition molecules") or in the extracellular matrix promote extension of the axons by providing an appropriate "adhesiveness" in the substrate. Both neurotrophic and neurite-outgrowth-promoting factors are essential for axonal growth after injury. Specificity in end-organ reinnervation is a complex phenomenon which may be based on physical factors at the zone of injury, as well as on molecular interaction between axons and substrate cells along the pathways and at the target level. Such processes may include molecular recognition of appropriate axons and maintenance of such axons by trophic mechanisms, as well as the pruning of inappropriate axons. The ultimate errors in target reinnervation are reflected in a cortical re-organization in the somatosensory cortex. The capacity of the brain to "reprogram" itself and adapt to this functional re-organization is critical for the ultimate recovery of functional sensory/motor function after nerve injuries.
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