| 61431. |
- Lutz, Barbara S., et al.
(författare)
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Nerve transfer to the median nerve using parts of the ulnar and radial nerves in the rabbit : effects on motor recovery of the median nerve and donor nerve morbidity
- 2000
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Ingår i: Journal of Hand Surgery - British and European Volume. - : SAGE Publications. - 0266-7681 .- 1532-2211. ; 25:4, s. 329-335
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Tidskriftsartikel (refereegranskat)abstract
- In this study, motor re-innervation of the median nerve by transfer of one-third, one-half, and two-thirds of either the agonistic ulnar nerve or the antagonistic radial nerve was investigated in both extremities of 20 rabbits.Recipient median nerve: Muscle contraction force of the flexor digitorum sublimus muscle after a one-third and a one-half of the ulnar nerve transfer achieved an average of 75 and 97% muscle power respectively as compared to conventional end-to-end neurorrhaphy. Muscle contraction force after one-third or one-half of the radial nerve transfer was significantly lower (36%).Donor nerves: Extensor carpi radialis muscle or flexor carpi ulnaris muscle contraction force 6 months postoperatively demonstrated a significant decrease after a one-half ulnar nerve and a two-thirds ulnar or radial nerve transfer, but not after a one-third transfer of either radial or ulnar nerves.Histologically, the number of axons in the re-innervated median nerve and both donor nerves distal to the coaptation site seemed to follow variable patterns.It was concluded that in the rabbit use of one-third of the agonistic ulnar nerve for re-innervation of the median nerve results in useful motor recovery with negligible donor site morbidity. Clinically, this technique may offer an alternative option for proximal nerve injuries or for free functioning muscle transplantations.
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| 61432. |
- Lutz, Barbara S., et al.
(författare)
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Role of the target in end-to-side neurorrhaphy : reinnervation of a single muscle vs. multiple muscles
- 2000
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Ingår i: Journal of reconstructive microsurgery. - : Georg Thieme Verlag KG. - 0743-684X .- 1098-8947. ; 16:6, s. 443-448
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Tidskriftsartikel (refereegranskat)abstract
- The authors examined the effects of end-to-side neurorrhaphy for reinnervation of the musculocutaneous nerve (Group A) which innervates the biceps muscle, compared to reinnervation of the median nerve which innervates multiple muscles in a rat model. Additionally, end-to-end neurorrhaphy to the musculocutaneous nerve using one-third of the median nerve (Group B) was investigated. End-to-end coaptation of the musculocutaneous nerve served as a control (Group C). In a grooming test, the biceps muscle function in Group A animals demonstrated a slower but nearly similar good recovery to Groups B and C. Biceps muscle contraction force investigated after 24 weeks demonstrated no statistically significant differences among all groups. In Groups A and B, no significant impairment of the donor median nerve function was found in a grasping test and the muscle contraction force of the flexor carpi radialis muscle, and histologic evaluation of the musculocutaneous nerve showed multiple regenerated axons distal to the coaptation site. Retrograde double-labeling in Group A animals showed reinnervation of the musculocutaneous nerve by median nerve axons located at the coaptation site. These results validate that end-to-side neurorrhaphy to a nerve innervating a single muscle is more efficient than to a nerve innervating multiple muscles, as demonstrated in an earlier study. The reason for this phenomenon is most likely that all sprouting axons are directed toward one target rather than toward multiple targets, with the latter situation resulting in a smaller number of axons and a variable distribution of axons per target. Since donor nerve sprouting axons were observed at the coaptation site, a relevance of the selected site for end-to-side neurorrhaphy is suggested. Both end-to-side neurorrhaphy and end-to-end neurorrhaphy, using one-third of the median nerve, led to useful functional recovery in this rat model, if an agonistic donor nerve is employed.
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| 61433. |
- Lutz, Barbara S., et al.
(författare)
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Selection of donor nerves : an important factor in end-to-side neurorrhaphy
- 2000
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Ingår i: British Journal of Plastic Surgery. - : Elsevier BV. - 0007-1226 .- 1465-3087. ; 53:2, s. 149-154
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Tidskriftsartikel (refereegranskat)abstract
- We have examined the effects of end-to-side neurorrhaphy on peripheral nerve regeneration usingthe median nerve as recipient nerve and either the antagonistic radial nerve or the agonistic ulnar nerve as donor nerves in rat upper limbs. A perineural window was created in all cases. Motor recovery up to 16 weeks postoperation was tested with the grasping test. No recovery of motor function was evident after end-to-side neurorrhaphy of the median nerve to the antagonistic radial nerve, whereas six of eight rats with end-to-side neurorrhaphy to the agonistic ulnar nerve achieved 367 g±47 g grasping power as compared to 526 g±6 g in end-to-end coapted control animals. No significant difference in flexor digitorum sublimus-motor nerve conduction velocity was found among all three groups. Radial nerve stimulation produced simultaneous contraction of both extensor and flexor muscles of the lower arm that disabled any coordinated movement of the paw. Histology (toluidine blue, acetylcholinesterase-stain) showed multiple regenerated (motor)-axons distal to the coaptation site in the median nerve. Reinnervation of the median nerve solely by the respective donor nerve was demonstrated by a retrograde double labelling technique. These results show that averaged 70% muscle power as compared to end-to-end neurorrhaphy with well coordinated muscle function can be achieved by axonal sprouting through end-to-side neurorrhaphy if an agonistic nerve is used as donor nerve. However, satisfying results are unpredictable. Antagonistic nerves show the ability to induce axonal regeneration, but no useful function can be expected.
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| 61434. |
- Lutz, Barbara S., et al.
(författare)
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Specificity of reinnervation and motor recovery after interposition of an artificial barrier between transected and repaired nerves in adjacency : an experimental study in the rat
- 2001
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Ingår i: Acta Neurochirurgica. - : Springer Science and Business Media LLC. - 0001-6268 .- 0942-0940. ; 143:4, s. 393-399
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Tidskriftsartikel (refereegranskat)abstract
- Non-specific re-innervation of target organs caused by misdirected axonal growth at the repair site is regarded as one reason for a poor functional outcome after peripheral nerve transsection and repair. This study investigates the rate of aberrant re-innervation and its influence on motor recovery in the rat sciatic nerve using artificial sheets as barrier between tibial and peroneal nerves.The sciatic nerve was transsected and repaired as follows: epineural sutures (A × 6), fascicular repair of tibial and peroneal nerves respectively (B × 8), and the same as in group B, but separating both nerves using an Integra®-sheet with silicone (C × 8), or Integra® without silicone (D × 8). As control, solely the tibial nerve was transsected and repaired (E × 5).Final investigations after 4 months revealed that in group C, 50% of the Integra®-silicone sheets were dislocated. No dislocation was found in group D. Muscle contraction force of the gastrocnemius muscle was significantly higher in group E as compared to all other groups. However although not significant, group D showed a consistently higher muscle contraction force than groups A, B, and C. Histology in groups A, B, and C with dislocated sheets demonstrated multiple axons growing from the tibial to the peroneal nerve and vice versa. In groups D and E, no such axonal growth was visible. These findings were confirmed by a significantly higher rate of specific re-innervation of the soleus muscle using sequential retrograde double labelling technique.Results of this study suggest that an artificial sheet such as Integra® bears the potential of preventing aberrant re-innervation between repaired adjacent nerves resulting in improved motor recovery. Clinically, this technique may be of importance for brachial plexus, sciatic nerve, and facial nerve repair.
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| 61435. |
- Lutz, Barbara, 1960-
(författare)
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Structural and functional regeneration of muscle-related axons after transection and repair of the rat sciatic nerve using nonvascularized autologous fascia as a barrier between tibial and peroneal nerve fascicles
- 2004
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Ingår i: Journal of reconstructive microsurgery. - : Georg Thieme Verlag KG. - 0743-684X .- 1098-8947. ; 20:8, s. 637-644
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Tidskriftsartikel (refereegranskat)abstract
- Aberrant reinnervation of target organs caused by misdirected axonal growth at the repair site is a major reason for the poor functional outcome usually seen after peripheral nerve transection and repair. This study investigates whether the criss-crossing of regenerating rat sciatic nerve axons between tibial and peroneal nerve fascicles can be reduced by using non-vascularized autologous fascia as a barrier.The left sciatic nerve was transected and repaired at midthigh as follows: epineurialy sutures (Group A); fascicular repair of tibial and peroneal nerve fascicles (Group B); fascicular repair of tibial and peroneal nerve fascicles separating the two fascicles by non-vascularized autologous fascia (Group C). In the control Group D, only the left tibial fascicle was transected and repaired. Five months postoperatively, the outcome of regeneration was evaluated by histology, by retrograde tracing, and by assessment of the contraction force of the gastrocnemius and tibial anterior muscles. The tracing experiments showed that muscle reinnervation was less abnormal in Group C than in Groups A and B. However, muscle contraction force was not better in Group C than in Groups A and B. With respect to the peroneal nerve innervated muscle, the contraction force in Group C was significantly lower than in Group B. The histologic picture indicated that this inferior result in Group C was due to nerve compression caused by fibrotic scar tissue at the site of the fascia graft.Results of this study show that a non-vascularized autologous fascial graft used as a barrier between two sutured nerve fascicles in adjacency reduces criss-crossing of regenerating axons between the fascicles, but causes significant nerve compression.
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| 61436. |
- Lutz, Barbara, 1960-
(författare)
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The role of a barrier between two nerve fascicles in adjacency after transection and repair of a peripheral nerve trunk
- 2004
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Ingår i: Neurological Research. - : Informa UK Limited. - 0161-6412 .- 1743-1328. ; 26:4, s. 363-370
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Tidskriftsartikel (refereegranskat)abstract
- Aberrant reinnervation of target organs caused by misdirected axonal growth at the repair site is a major reason for the poor functional outcome usually seen after peripheral nerve transection and repair. The following two studies investigate whether criss-crossing of regenerating rat sciatic nerve axons between tibial and peroneal nerve fascicles can be reduced by using a barrier at the coaption site. The left sciatic nerve was transected and repaired at mid-thigh as follows: epineural sutures (group A, A-II), fascicular repair of tibial and peroneal nerve fascicles (group B, B-II), fascicular repair of tibial and peroneal nerve fascicles separating the two fascicles with a pedicled fat flap (group C), Integra® (group D) or non-vascularized autologous fascia (group C-II). In the control groups E and D-II, only the left tibial fascicle was transected and repaired. Four and 5 months postoperatively, the outcome of regeneration was evaluated by histology, by retrograde tracing, and by assessment of the muscle force of the gastrocnemius and tibial anterior muscles. The tracing experiments showed that specificity of muscle reinnervation significantly improved when a barrier was employed, which significantly or clearly improved muscle twitch tension in groups C and D. However, muscle contraction force was not better when fascia was used as barrier. The histological picture indicated that this inferior result in group C-II was due to nerve compression caused by fibrotic scar tissue at the site of the fascia graft. Results of this study show that a pedicle fat flap and Integra® used as barrier significantly prevent aberrant reinnervation between two sutured nerve fascicles in adjacency resulting in improved motor recovery in rats. Non-vascularized autologous fascia however, reduces also criss-crossing of regenerating axons between the fascicles, but causes significant nerve compression.
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| 61437. |
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| 61438. |
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| 61439. |
- Lützhöft, Margareta H., et al.
(författare)
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On Your Watch : Automation on the Bridge
- 2002
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Ingår i: Journal of navigation (Print). - : Cambridge University Press. - 0373-4633 .- 1469-7785. ; 55:1, s. 83-96
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we discuss the grounding of the Royal Majesty, reconstructed from the perspective of the crew. The aim is particularly to understand the role of automation in shaping crew assessments and actions. Automation is often introduced because of quantitative promises that: it will reduce human error; reduce workload; and increase efficiency. But as demonstrated by the Royal Majesty, as well as by numerous research results, automation has qualitative consequences for human work and safety, and does not simply replace human work with machine work. Automation changes the task it was meant to support; it creates new error pathways, shifts consequences of error further into the future and delays opportunities for error detection and recovery. By going through the sequence of events that preceded the grounding of the Royal Majesty, we highlight the role that automation plays in the success and failure of navigation today. We then point to future directions on how to make automated systems into better team players.
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| 61440. |
- Lützhöft, Margareta, et al.
(författare)
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Piloting by heart and by chart
- 2006
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Ingår i: Journal of navigation (Print). - 0373-4633 .- 1469-7785. ; 59:2, s. 221-237
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the complexity of the Baltic archipelago, and the navigational and operational processes involved in piloting these waters. This four year ethnographic study shows how piloting is learned, performed, and passed on to the next generation of pilots. The blend of new technology and old methods is discussed, the indivisibility of working and learning, and the individuality of the mental constructs of the mariners/pilots.
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