Articles: traumatic-brain-injuries.
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Journal of neurotrauma · Jan 2017
TREM2 deficiency alters acute macrophage distribution and improves recovery after TBI.
Traumatic brain injury (TBI) affects 1.7 million persons annually in the United States (Centers for Disease Control and Prevention). There is increasing evidence that persons exposed to TBI have increased risk of the development of multiple neurodegenerative conditions, including Alzheimer disease (AD). TBI triggers a strong neuroinflammatory response characterized by astrogliosis, activation of microglia, and infiltration of peripheral monocytes. ⋯ Further, Trem2-/- mice exposed to TBI exhibited enhanced macrophage activation near the lesion, but significantly less macrophage activation away from the lesion when compared with B6 mice exposed to TBI. In addition, at 120 DPI, Trem2-/- mice exposed to TBI demonstrated reduced hippocampal atrophy and rescue of TBI-induced behavioral changes when compared with B6 mice exposed to TBI. Taken together, this study suggests that TREM2 deficiency influences both acute and chronic responses to TBI, leading to an altered macrophage response at early time points, and improved pathological and functional outcomes at later time points.
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Journal of neurotrauma · Jan 2017
Hemolysed blood elicits - calcium antagonist and high CO2 reversible - constrictions via elevation of Ca2+ in isolated cerebral arteries.
During acute subarachnoid hemorrhage, blood is hemolyzed, which is followed by a significant cerebrovascular spasm resulting in a serious clinical condition. Interestingly, however, the direct vasomotor effect of perivascular hemolyzed blood (HB) has not yet been characterized, preventing the assessment of contribution of vasoconstrictor mechanisms deriving from brain tissue and/or blood and development of possible treatments. We hypothesized that perivascular HB reduces the diameter of the cerebral arteries (i.e., basilar artery [BA]; middle cerebral artery [MCA]) by elevating vascular tissue [Ca2+]i level. ⋯ After washout of HB, nitric oxide-mediated dilations remained significantly reduced compared to control. HB significantly increased the ratiometric Ca signal, which returned to control level after washout. In conclusion, perivascular hemolyzed blood elicits significant-nifedipine and high CO2 reversible-constrictions of isolated BAs and MCAs, primarily by increasing intracellular Ca2+, findings that can contribute to the refinement of local treatment of subarachnoid hemorrhage.
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Journal of neurotrauma · Jan 2017
Comprehensive Profiling of Modulation of Nitric Oxide levels and Mitochondrial Activity in Injured Brain: An Experimental Study based on the Fluid Percussion Injury Model in Rats.
Nitric oxide (NO) has frequently been associated with secondary damage after brain injury. However, average NO levels in different brain regions before and after traumatic brain injury (TBI) and its role in post-TBI mitochondrial dysfunction remain unclear. In this comprehensive profiling study, we demonstrate for the first time that basal NO levels vary significantly in the healthy cortex (0.44 ± 0.04 μM), hippocampus (0.26 ± 0.03 μM), and cerebellum (1.24 ± 0.08 μM). ⋯ NO-mediated impairment of mitochondrial state 3 respiration dependent on complex I substrates was transient and confined to the ipsilateral cortex. Our results demonstrate that NO dynamics and associated effects differ in various regions of the injured brain. A potential association between the observed mitochondrial electron flow through complex I, but not complex II, and the modulation of TBI induced NO levels in different brain regions has to be prospectively analyzed in more detail.
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Epilepsy is a common and debilitating consequence of traumatic brain injury (TBI). Seizures contribute to progressive neurodegeneration and poor functional and psychosocial outcomes for TBI survivors, and epilepsy after TBI is often resistant to existing anti-epileptic drugs. The development of post-traumatic epilepsy (PTE) occurs in a complex neurobiological environment characterized by ongoing TBI-induced secondary injury processes. Neuroinflammation is an important secondary injury process, though how it contributes to epileptogenesis, and the development of chronic, spontaneous seizure activity, remains poorly understood. A mechanistic understanding of how inflammation contributes to the development of epilepsy (epileptogenesis) after TBI is important to facilitate the identification of novel therapeutic strategies to reduce or prevent seizures. BODY: We reviewed previous clinical and pre-clinical data to evaluate the hypothesis that inflammation contributes to seizures and epilepsy after TBI. Increasing evidence indicates that neuroinflammation is a common consequence of epileptic seizure activity, and also contributes to epileptogenesis as well as seizure initiation (ictogenesis) and perpetuation. Three key signaling factors implicated in both seizure activity and TBI-induced secondary pathogenesis are highlighted in this review: high-mobility group box protein-1 interacting with toll-like receptors, interleukin-1β interacting with its receptors, and transforming growth factor-β signaling from extravascular albumin. Lastly, we consider age-dependent differences in seizure susceptibility and neuroinflammation as mechanisms which may contribute to a heightened vulnerability to epileptogenesis in young brain-injured patients. ⋯ Several inflammatory mediators exhibit epileptogenic and ictogenic properties, acting on glia and neurons both directly and indirectly influence neuronal excitability. Further research is required to establish causality between inflammatory signaling cascades and the development of epilepsy post-TBI, and to evaluate the therapeutic potential of pharmaceuticals targeting inflammatory pathways to prevent or mitigate the development of PTE.
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Randomized Controlled Trial
The efficacy of prospective memory rehabilitation plus metacognitive skills training for adults with traumatic brain injury: study protocol for a randomized controlled trial.
Impairment of prospective memory (PM) is common following traumatic brain injury (TBI) and negatively impacts on independent living. Compensatory approaches to PM rehabilitation have been found to minimize the impact of PM impairment in adults with TBI; however, poor self-awareness after TBI poses a major barrier to the generalization of compensatory strategies in daily life. Metacognitive skills training (MST) is a cognitive rehabilitation approach that aims to facilitate the development of self-awareness in adults with TBI. This paper describes the protocol of a study that aims to evaluate the efficacy of a MST approach to compensatory PM rehabilitation for improving everyday PM performance and psychosocial outcomes after TBI. ⋯ This study seeks to determine the efficacy of COMP-MST for improving and maintaining everyday PM performance and level of psychosocial integration in adults with moderate to severe TBI. The findings will advance theoretical understanding of the role of self-awareness in compensatory PM rehabilitation and skills generalization. COMP-MST has the potential to reduce the cost of rehabilitation and lifestyle support following TBI because the intervention could enhance generalization success and lifelong application of PM compensatory strategies.