Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
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J. Cereb. Blood Flow Metab. · Apr 2014
Repeated mild traumatic brain injury results in long-term white-matter disruption.
Mild traumatic brain injury (mTBI) is an increasing public health concern as repetitive injuries can exacerbate existing neuropathology and result in increased neurologic deficits. In contrast to other models of repeated mTBI (rmTBI), our study focused on long-term white-matter abnormalities after bilateral mTBIs induced 7 days apart. A controlled cortical impact (CCI) was used to induce an initial mTBI to the right cortex of Single and rmTBI Sprague Dawley rats, followed by a second injury to the left cortex of rmTBI animals. ⋯ Further, the rmTBI group showed an increased g-ratio and axon caliber in addition to myelin sheath abnormalities using TEM. Our DTI results indicate ongoing myelin changes, while the TEM data show continuing axonal changes at 60 days after rmTBI. These data suggest that bilateral rmTBI induced 7 days apart leads to progressive alterations in white matter that are not observed after a single mTBI.
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J. Cereb. Blood Flow Metab. · Mar 2014
CR8, a novel inhibitor of CDK, limits microglial activation, astrocytosis, neuronal loss, and neurologic dysfunction after experimental traumatic brain injury.
Central nervous system injury causes a marked increase in the expression of cell cycle-related proteins. In this study, we show that cell cycle activation (CCA) is detected in mature neurons at 24 hours after rat lateral fluid percussion (LFP)-induced traumatic brain injury (TBI), as reflected by increased expression of cyclin G1, phosphorylated retinoblastoma (phospho-Rb), E2F1 and proliferating cell nuclear antigen (PCNA). These changes were associated with progressive cortical, hippocampal, and thalamic neuronal loss and microglial and astrocyte activation. ⋯ A delayed systemic post-LFP administration at 3 hours of CR8--a potent second-generation cyclin-dependent kinase (CDK) inhibitor--reduced CCA; cortical, hippocampal, and thalamic neuronal loss; and cortical microglial and astrocyte activation. Furthermore, CR8 treatment attenuated sensorimotor and cognitive deficits, alleviated depressive-like symptoms, and decreased lesion volume. These findings underscore the contribution of CCA to progressive neurodegeneration and chronic neuroinflammation following TBI, and demonstrate the neuroprotective potential of cell cycle inhibition in a clinically relevant experimental TBI model.
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J. Cereb. Blood Flow Metab. · Mar 2014
Rivaroxaban does not increase hemorrhage after thrombolysis in experimental ischemic stroke.
The management of acute ischemic stroke during anticoagulation with a novel oral anticoagulant (NOAC) is challenging because intravenous thrombolysis is contraindicated because of a putative increased risk of intracerebral hemorrhagic complications. We examined the risk of secondary postischemic hemorrhage after thrombolysis in rodents pretreated with rivaroxaban or warfarin. Mice were pretreated with either rivaroxaban (30 mg/kg), warfarin (target international normalized ratio 2 to 3) or vehicle. ⋯ Blood-brain barrier permeability was significantly higher in the warfarin group compared with rivaroxaban and control. Thus, rivaroxaban in contrast to warfarin does not increase secondary hemorrhage after thrombolysis in experimental cerebral ischemia. Less effects of rivaroxaban on postischemic BBB permeability may account for this difference.
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J. Cereb. Blood Flow Metab. · Feb 2014
Review Meta AnalysisCT perfusion and delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis.
Delayed cerebral ischemia (DCI) is at presentation a diagnosis per exclusionem, and can only be confirmed with follow-up imaging. For treatment of DCI a diagnostic tool is needed. We performed a systematic review to evaluate the value of CT perfusion (CTP) in the prediction and diagnosis of DCI. ⋯ Perfusion thresholds reported in studies were comparable, although the corresponding test characteristics were moderate and differed between studies. We conclude that CTP can be used in the diagnosis but not in the prediction of DCI. A need exists to standardize the method for measuring perfusion with CTP after SAH, and optimize and validate perfusion thresholds.
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J. Cereb. Blood Flow Metab. · Feb 2014
Hypothalamic astroglial connexins are required for brain glucose sensing-induced insulin secretion.
Hypothalamic glucose detection participates in maintaining glycemic balance, food intake, and thermogenesis. Although hypothalamic neurons are the executive cells involved in these responses, there is increasing evidence that astrocytes participate in glucose sensing (GS); however, it is unknown whether astroglial networking is required for glucose sensitivity. Astroglial connexins 30 and 43 (Cx30 and Cx43) form hexameric channels, which are apposed in gap junctions, allowing for the intercellular transfer of small molecules such as glucose throughout the astroglial networks. ⋯ Both fasting and high glycemic levels rapidly altered the protein levels of MBH astroglial connexins, suggesting cross talk within the MBH between glycemic status and the connexins' ability to dispatch glucose. Finally, the inhibition of MBH Cx43 (by transient RNA interference) attenuated hypothalamic glucose sensitivity in rats, which was demonstrated by a pronounced decreased insulin secretion in response to a brain glucose challenge. These results illustrate that astroglial connexins contribute to hypothalamic GS.