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- Aare, Magnus, et al.
(författare)
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Injury tolerances for oblique impact helmet testing
- 2004
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Ingår i: International Journal of Crashworthiness. - : Informa UK Limited. - 1358-8265 .- 1754-2111. ; 9:1, s. 15-23
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Tidskriftsartikel (refereegranskat)abstract
- The most frequently sustained severe injuries in motorcycle crashes are injuries to the head, and many of these are caused by rotational force. Rotational force is most commonly the result of oblique impacts to the head. Good testing methods for evaluating the effects of such impacts are currently lacking. There is also a need for improving our understanding of the effects of oblique impacts on the human head. Helmet standards currently in use today do not measure rotational effects in test dummy heads. However rotational force to the head results in large shear strains arising in the brain, which has been proposed as a cause of traumatic brain injuries like diffuse axonal injuries (DAI). This paper investigates a number of well-defined impacts, simulated using a detailed finite element (FE) model of the human head, an FE model of the Hybrid III dummy head and an FE model of a helmet. The same simulations were performed on both the FE human head model and the FE Hybrid III head model, both fitted with helmets. Simulations on both these heads were performed to describe the relationship between load levels in the FE Hybrid III head model and strains in the brain tissue in the FE human head model. In this study, the change in rotational velocity and the head injury criterion (HIC) value were chosen as appropriate measurements. It was concluded that both rotational and translational effects are important when predicting the strain levels in the human brain.
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- Aarsland, D, et al.
(författare)
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Are Parkinson's disease with dementia and dementia with Lewy bodies the same entity?
- 2004
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Ingår i: Journal of geriatric psychiatry and neurology. - : SAGE Publications. - 0891-9887 .- 1552-5708. ; 17:3, s. 137-145
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Tidskriftsartikel (refereegranskat)abstract
- The diagnosis of Parkinson’s disease with dementia (PDD) or dementia with Lewy bodies (DLB) is based on an arbitary distinction between the time of onset of motor and cognitive symptoms. These syndromes share many neurobiological similarities, but there are also differences. Deposition of beta-amyloid protein is more marked and more closely related to cognitive impairment in DLB than PDD, possibly contributing to dementia at onset. The relatively more severe executive impairment in DLB than PDD may relate to the loss of frontohippocampal projections in DLB. Visual hallucinations and delusions associate with more abundant Lewy body pathology in temporal cortex in DLB. The differential involvement of pathology in the striatum may account for the differences in parkinsonism. Longitudinal studies with neuropathological and neurochemical evaluations will be essential to enable more robust comparisons and determine pathological substrates contributing to the differences in cognitive, motor, and psychiatric symptoms. ( J Geriatr Psychiatry Neurol 2004; 17:137-145)
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| 6. |
- Aarsland, D, et al.
(författare)
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Psychiatric issues in non-Alzheimer dementias
- 2004
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Ingår i: CLINICAL NEUROSCIENCE RESEARCH. - : Elsevier BV. - 1566-2772. ; 3:6, s. 397-412
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Forskningsöversikt (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Aarsland, D, et al.
(författare)
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Role of cholinesterase inhibitors in Parkinson's disease and dementia with Lewy bodies
- 2004
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Ingår i: Journal of geriatric psychiatry and neurology. - : SAGE Publications. - 0891-9887 .- 1552-5708. ; 17:3, s. 164-171
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Tidskriftsartikel (refereegranskat)abstract
- This article reviews the cholinergic changes in Parkinson’s disease and dementia (PDD) and dementia with Lewy bodies (DLB), their potential clinical implications, and the available evidence for cholinesterase inhibitors in the treatment of PDD and DLB. Marked neuronal loss of cholinergic nuclei, reduced cholinergic markers in the neocortex, hippocampus, and selected thalamic nuclei, and receptor changes have been reported. One large and 2 small placebo-controlled trials and nearly 20 open-label studies suggest that cholinesterase inhibitors have a positive effect on cognition, psychiatric symptoms, and global function in patients with DLB and PDD. The treatment is well tolerated in most patients without any apparent worsening of extrapyramidal motor features. Given the high risk of severe sensitivity reactions and increased risk of cerebrovascular incidents during treatment with neuroleptics, more clinical trials of cholinesterase inhibitors are encouraged to establish their precise role in DLB and PDD. ( J Geriatr Psychiatry Neurol 2004; 17:164-171)
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| 9. |
- Aarum, Johan
(författare)
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Interactions between mouse CNS cells : microglia and neural precursor cells
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The mammalian central nervous system (CNS) contains a variety of cells, all specialized to perform different functions. Most numerous are the three types of glia cells, whose basic role is to support the signaling units of the CNS, the neurons. The perspective of this thesis is from the glia cells; particularly the microglia cells, a non-neural population of cells that are spread throughout the CNS. In the healthy CNS these cells are resting, but as a consequence of various CNS disturbances they rapidly become activated, frequently together with astrocytes, the second type of glia cells (oligodendrocytes being the third). This can happen slowly, as in neurodegenerative diseases, or quickly as in acute CNS lesions such as stroke. Both processes involve microglia cells, and sometimes macrophages from the circulation. These latter cells are difficult to distinguish from the microglia cells. In an effort to generate microglia specific markers we used phage display technology to select microglia specific peptides from a random peptide library displayed on the phage surface. Two sets of selection strategies were compared with regard to phage-clone enrichment. The first strategy was based on phage binding to monolayers of primary microglia fixed to a solid surface, while the second strategy was based on fluorescence activated cell sorting (FACS) of microglia cells with bound phages. The latter protocol was found to be superior. Five phage-clones that preferentially bound to microglia cells were isolated. One of the selected clones was shown to be microglia specific by free peptide inhibition and selective in binding to microglia cells, as compared to blood-derived monocytes. Much of our current knowledge in neurobiology derives from studies of cells in culture, a less complex substitute for in vivo studies. As a bridge between monolayer CNS cell cultures and in vivo animal models we set up a three-dimensional culture system, so called aggregate cultures from mouse CNS cells. These aggregates were characterized in detail regarding cellular composition and dynamics, as well as the expression of several neuropeptides and neurotransmitters. All the principle brain cells were present in the aggregates and their numbers changed over time, neurons being the most numerous. The cells appeared to mature as judged by their morphology and, in the case of neurons, the increased expression of synapse specific proteins. Among the investigated neuropeptides, enkephalin and dynorphin were the most abundant followed by galanin, approximating their expression in CNS development. We also found that neural precursor cells, capable of self-renewal and differentiation into neurons, astrocytes and oligodendrocytes, were maintained in the aggregates, even after more than two months of culturing. Treating the aggregates with EGF led to the formation of an outer layer of nestin-positive precursor cells. Using the aggregate culture in part, we found that factor(s) secreted from microglia cells attracts neural precursor cells in a chemotactic manner. This finding may explain the preferred migration of precursor cells to sites of CNS injury. Furthermore, microglia derived factors could affect the differentiation of neural precursor cells, such that more neurons were formed. Together these results suggest important functions of microglia cells in CNS development and pathology. It is reasonable to believe that the migration of neural precursor cells is directed both by attractant and repellant cues. Reactive astrocytes are well known to inhibit growing axons and recently also suggested to inhibit the migration of neural precursor cells. We show that astrocytes in culture repel neural precursor cells and that this effect is mediated by secreted Slit proteins. This conclusion is based on several observations; astrocytes produce Slit and the astrocyte-repellant effect was blocked by the ectodomain of the Slit receptor, and finally, recombinant Slit could substitute for astrocyte derived Slit. Knowledge about the interplay between attractive and repulsive cues may be important for the manipulation of neural precursor cells for medical purposes.
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