| 11. |
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| 12. |
- Patton, D. A., et al.
(författare)
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The biomechanical determinants of concussion : Finite element simulations to investigate brain tissue deformations during sporting impacts to the unprotected head
- 2013
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Ingår i: Journal of Applied Biomechanics. - : Human Kinetics. - 1065-8483 .- 1543-2688. ; 29:6, s. 721-730
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Tidskriftsartikel (refereegranskat)abstract
- Concussion is an injury of specific interest in collision and contact sports, resulting in a need to develop effective preventive strategies. A detailed finite element model of the human head was used to approximate the regional distribution of tissue deformations in the brain by simulating reconstructions of unhelmeted concussion and no-injury head impacts. The results were evaluated using logistic regression analysis and it was found that angular kinematics, in the coronal plane, and maximum principal strains, in all regions of the brain, were significantly associated with concussion. The results suggested that impacts to the temporal region of the head cause coronal rotations, which render injurious strain levels in the brain. Tentative strain tolerance levels of 0.13, 0.15, and 0.26 in the thalamus, corpus callosum, and white matter, respectively, for a 50% likelihood of concussion were determined by logistic regression. The tentative strain tolerance levels compared well with previously reported results from reconstruction studies of American football and single axon, optic nerve, and brain slice culture model studies. The methods used in the current study provide an opportunity to collect unique kinematic data of sporting impacts to the unprotected head, which can be employed in various ways to broaden the understanding of concussion.
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| 13. |
- Hånell, Anders, et al.
(författare)
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Genetic Deletion and Pharmacological Inhibition of Nogo-66 Receptor Impairs Cognitive Outcome after Traumatic Brain Injury in Mice
- 2010
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Ingår i: Journal of Neurotrauma. - : Mary Ann Liebert Inc. - 0897-7151 .- 1557-9042. ; 27:7, s. 1297-1309
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Tidskriftsartikel (refereegranskat)abstract
- Functional recovery is markedly restricted following traumatic brain injury (TBI), partly due to myelin-associated inhibitors including Nogo-A, myelin-associated glycoprotein (MAG) and oligodendrocyte myelin glycoprotein (OMgp), that all bind to the Nogo-66 receptor-1 (NgR1). In previous studies, pharmacological neutralization of both Nogo-A and MAG improved outcome following TBI in the rat, and neutralization of NgR1 improved outcome following spinal cord injury and stroke in rodent models. However, the behavioral and histological effects of NgR1 inhibition have not previously been evaluated in TBI. We hypothesized that NgR1 negatively influences behavioral recovery following TBI, and evaluated NgR1(-/-) mice (NgR1(-/-) study) and, in a separate study, soluble NgR1 infused intracerebroventricularly immediately post-injury to neutralize NgR1 (sNgR1 study) following TBI in mice using a controlled cortical impact (CCI) injury model. In both studies, motor function, TBI-induced loss of tissue, and hippocampal beta-amyloid immunohistochemistry were not altered up to 5 weeks post-injury. Surprisingly, cognitive function (as evaluated with the Morris water maze at 4 weeks post-injury) was significantly impaired both in NgR1(-/-) mice and in mice treated with soluble NgR1. In the sNgR1 study, we evaluated hippocampal mossy fiber sprouting using the Timm stain and found it to be increased at 5 weeks following TBI. Neutralization of NgR1 significantly increased mossy fiber sprouting in sham-injured animals, but not in brain-injured animals. Our data suggest a complex role for myelin-associated inhibitors in the behavioral recovery process following TBI, and urge caution when inhibiting NgR1 in the early post-injury period.
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| 14. |
- McIntosh, Angus R., et al.
(författare)
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The impact of trout on galaxiid fishes in New Zealand
- 2010
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Ingår i: New Zealand Journal of Ecology. - 0110-6465. ; 34:1, s. 195-206
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Tidskriftsartikel (refereegranskat)abstract
- Compared with the effect of invaders on the native terrestrial fauna of New Zealand, interactions between native fishes and introduced trout (sports fish in the genera Salmo, Oncorhynchus and Salvelinus) are less well known and there have been fewer efforts to remedy their effects. Trout have caused widespread reductions in the distribution and abundance of native galaxiid fishes, a family dominated by threatened species. The effects have been most severe on non-diadromous species (those lacking a marine migratory stage), which are commonly eliminated from streams by trout. Galaxiid populations in lakes, and those with migratory 'whitebait' stages, have also been affected, but the extent of the impacts are less understood. The mechanisms controlling negative interactions between trout and native fish, and how the environment modifies those interactions, will be important for future management. Experiments and field comparisons indicate size-specific predation by trout is the main driver of negative interactions. Large trout (> 150 mm long) do the greatest damage and small galaxiids (those with adult sizes < 150 mm long) are the most at risk. The fry stage of non-diadromous galaxiids is particularly vulnerable. Despite galaxiid fry production in some trout-invaded reaches, often no fry survive making them population 'sinks' that must be sustained by adult dispersal. Trout are also associated with changes in galaxiid behaviour and alterations to stream benthic communities. However, effects on galaxiid growth and fecundity have been little studied. Recent work also indicates that habitat conditions, especially floods, low flows and natural acidity, can mediate trout-galaxiid interactions. We argue that managers should be more proactive in their response to the plight of galaxiids, and we identify avenues of research that will benefit native fish conservation activities in the future.
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