Vance Fredrickson

Neuronal damage and functional deficits are ameliorated by inhibition of aquaporin and HIF1α after traumatic brain injury (TBI)

The present study, using a rodent model of closed-head diffuse traumatic brain injury (TBI), investigated the role of dysregulated aquaporins (AQP) 4 and 9, as well as hypoxia inducible factor -1α(HIF-1α) on brain edema formation, neuronal injury, and functional deficits. TBI was induced in adult (400-425 g), male Sprague-Dawley rats using a modified Marmarous head impact-acceleration device (450 g weight dropped from 2m height). Animals in each treatment group were administered intravenous anti-AQP4 or -AQP9 antibodies or 2-Methoxyestradiol (2ME2, an inhibitor of HIF-1α) 30 min after injury. At 24h post-TBI, animals (n=6 each group) were sacrificed to examine the extent of brain edema by water content, as well as protein expression of AQP and HIF-1α by Western immune-blotting. At 48-hours post-TBI, neuronal injury (n=8 each group) was assessed by FluoroJade (FJ) histochemistry. Spatial learning and memory deficits were evaluated by radial arm maze (n=8 each group) up to 21 days post-TBI. Compared to non-injured controls, significant (p<0.05) increases in the expression of AQP4 and -9 were detected in the brains of injured animals. In addition, significant (p<0.05) brain edema after TBI was associated with increases (p <0.05) both in neuronal injury (FJ labeling) and neurobehavioral deficits. Selective inhibition of either AQP4 or -9, or HIF-1α significantly (p<0.05) decreased the expression of the proteins. In addition, inhibition of the AQPs and HIF-1α significantly (p<0.05) ameliorated brain edema, as well as the number of injured neurons in cortical layers II/III and V/VI, striatum and hippocampal regions CA1/CA3. Finally, compared to the non-treated TBI animals, AQP or HIF-1α inhibition significantly (p<0.01) improved neurobehavioral outcomes after TBI. Taken together, the present data supports a causal relation between HIF-AQP mediated cerebral edema, secondary neuronal injury, and tertiary behavioral deficits post-TBI. The data further suggests that upstream modulation of the molecular patho-trajectory effectively ameliorates both neuronal injury and behavioral deficits post-TBI.

Synergetic Neuroprotection of Normobaric Oxygenation and Ethanol in Ischemic Stroke Through Improved Oxidative Mechanism

Background and Purpose— Normobaric oxygenation (NBO) and ethanol both provide neuroprotection in stroke. We evaluated the enhanced neuroprotective effect of combining these 2 treatments in a rat stroke model. Methods— Sprague-Dawley rats were subjected to middle cerebral artery occlusion for 2 hours. Reperfusion was then established and followed by treatment with either (1) an intraperitoneal injection of ethanol (1.0 g/kg), (2) NBO treatment (2-hour duration), or (3) NBO plus ethanol. The extent of brain injury was determined by infarct volume and motor performance. Oxidative metabolism was determined by ADP/ATP ratios, reactive oxygen species levels, nicotinamide adenine dinucleotide phosphate oxidase activity, and pyruvate dehydrogenase activity. Protein expression of major nicotinamide adenine dinucleotide phosphate oxidase subunits (p47phox, gp91phox, and p67phox) and the enzyme pyruvate dehydrogenase was evaluated through Western immunoblotting. Results— NBO and ethanol monotherapies each demonstrated reductions as compared to stroke without treatment in infarct volume (36.7% and 37.9% vs 48.4%) and neurological deficits (score of 6.4 and 6.5 vs 8.4); however, the greatest neuroprotection (18.8% of infarct volume and 4.4 neurological deficit) was found in animals treated with combination therapy. This neuroprotection was associated with the largest reductions in ADP/ATP ratios, reactive oxygen species levels, and nicotinamide adenine dinucleotide phosphate oxidase activity, and the largest increase in pyruvate dehydrogenase activity. Conclusions— Combination therapy with NBO and ethanol enhances the neuroprotective effect produced by each therapy alone. The mechanism behind this synergistic action is related to changes in cellular metabolism after ischemia reperfusion. NBO plus ethanol is attractive for clinical study because of its ease of use, tolerability, and tremendous neuroprotective potential in stroke.

Acute ethanol treatment reduces blood–brain barrier dysfunction following ischemia/reperfusion injury

BACKGROUND AND PURPOSE Ethanol has been shown to provide neuroprotective effects, but the precise mechanisms by which these effects occur have yet to be investigated. In this study, we investigate blood-brain barrier (BBB) and edema level changes in association with expression of matrix metalloproteinases (MMP-2 and MMP-9) and aquaporins (AQP-4 and AQP-9) in ethanol treated rats following middle cerebral artery (MCA) occlusion. METHODS An ischemic stroke model was generated by occlusion of the right MCA for 2h in male Sprague-Dawley rats (n=72). Edema levels and BBB integrity following the ischemic event were studied by quantification of brain water content and extravasation of Evans blue following 24 and 48h of reperfusion, respectively. Expression of the proteins MMP-2 and MMP-9, as well as AQP-4 and AQP-9, were determined by Western blot analysis 3 and 24h after reperfusion. RESULTS Treatment with ethanol significantly reduced brain edema (P<0.01) and BBB dysfunction (P<0.05) when compared to the saline-treated control groups. The upregulation of MMP-2 and MMP-9, as well as AQP-4 and AQP-9, following ischemia/reperfusion, was significantly reduced in ethanol-treated groups (P<0.05). CONCLUSIONS Ethanol ameliorates brain edema and BBB disruption after stroke, in association with a reduction in the expression of MMPs and AQPs. These results provide clues to ethanols neuroprotective properties.

Enhanced Neuroprotection by Local Intra-Arterial Infusion of Human Albumin Solution and Local Hypothermia

Background and Purpose— We investigated the potential benefit of using a local infusion of low-dose and cold human albumin in ischemic rats as compared with systemic delivery. Methods— Stroke was induced in rats, and at 2 hours treatment groups received 0°C saline or low-dose albumin at 0°C or 37°C infused into the ischemic area. Results— The local low-dose cold albumin infusion, which achieved the hypothermic temperature (P<0.001), produced the greatest reduction in infarct volume and the best recovery of neurological function. Conclusions— The local low-dose cold albumin infusion into the ischemic area offered a combination of regional brain hypothermia and albumin administration, which enhanced neuroprotection and would be beneficial in the clinical setting.

Reduction of brain edema and expression of aquaporins with acute ethanol treatment after traumatic brain injury

OBJECT Previous studies have demonstrated that traumatic brain injury (TBI) causes brain edema by allowing excessive water passage through aquaporin (AQP) proteins. To establish the potential neuroprotective properties of ethanol as a post-TBI therapy, in the present study the authors determined the effect of ethanol on brain edema, AQP expression, and functional outcomes in a post-TBI setting. METHODS Adult male Sprague-Dawley rats weighing between 425 and 475 g received a closed head TBI in which Maramarous impact-acceleration method was used. Animals were given a subsequent intraperitoneal injection of 0.5 g/kg or 1.5 g/kg ethanol at 60 minutes post-TBI and were killed 24 hours after TBI. Brains were subsequently examined for edema along with AQP mRNA and protein expression. Additional animals treated with either 0.5 g/kg or 1.5 g/kg ethanol at 60 minutes post-TBI were designated for cognitive and motor testing for 3 weeks. RESULTS Ethanol administration post-TBI led to significantly (p < 0.05) lower levels of brain edema as measured by brain water content. This downregulation in brain edema was associated with significantly (p < 0.05) reduced levels of AQP mRNA and protein expression as compared with TBI without treatment. These findings concur with cognitive studies in which ethanol-treated animals exhibited significantly (p < 0.05) faster radial maze completion times. Motor behavioral testing additionally demonstrated significant (p < 0.05) beneficial effects of ethanol, with treated animals displaying improved motor coordination when compared with untreated animals. CONCLUSIONS The present findings suggest that acute ethanol administration after a TBI decreases AQP expression, which may lead to reduced cerebral edema. Ethanol-treated animals additionally showed improved cognitive and motor outcomes compared with untreated animals.

Bickerstaff’s brainstem encephalitis, Miller Fisher syndrome and Guillain-Barré syndrome overlap in an asthma patient with negative anti-ganglioside antibodies

BackgroundBickerstaff’s brainstem encephalitis (BBE), together with Miller Fisher syndrome (MFS) and Guillain-Barré syndrome (GBS) were considered to form a continuous clinical spectrum. An anti-GQ1b antibody syndrome has been proposed to underlie the common pathophysiology for the three disorders; however, other studies have found a positive anti-GM1 instead of anti-GQ1b antibody.Case presentationHere we report a 20-year-old male patient with overlapping BBE, MFS and GBS. The patient had a positive family history of bronchial asthma and had suffered from the condition for over 15 years. He developed BBE symptoms nine days after an asthma exacerbation. During the course of illness, he had significantly elevated IgE levels in both serum and cerebrospinal fluid. Serologic analysis of antibodies against ganglioside complexes (anti-GDIa, anti-GDIb, anti-GM1, anti-GM2, anti-GM3, anti-GQIb and anti-GTIb antibodies) showed negative results.ConclusionsSince asthma has recently been related to autoimmune disease, our case supports an autoimmune mechanism underlying the clinical spectrum composed of BBE, MFS and GBS. However, contrary to a proposed anti-GQ1b antibody syndrome, we would suggest that pathogenesis of this clinical spectrum is not limited to anti-ganglioside antibodies.

The effect of a microcatheter-based selective intra-arterial hypothermia on hemodynamic changes following transient cerebral ischemia

Abstract Objectives: We investigated the effect of a microcatheter-based selectively induced intra-arterial hypothermia on hemodynamic changes following transient cerebral ischemia in rats. Methods: Stroke was induced in male Sprague-Dawley rats by a two-hour middle cerebral artery occlusion (MCAO) using a microcatheter. After the two-hour MCAO, 0·9% cold saline (0°C) was selectively infused through a microcatheter. Cerebral blood flow (CBF) in the ischemic brain region was continuously monitored by Laser-Doppler flowmetry (LDF) during the procedure. Following ischemia/reperfusion, serial functional neurologic testing was performed, and cerebral infarct volume was evaluated after 48 hours. Results: The local cold saline infusion, via a microcatheter, achieved a rapid induction of brain hypothermia (cerebral cortex from 37·1 ± 0·3 to 30·7 ± 0·4°C; striatum from 37·5 ± 0·3 to 30·9 ± 0·5°C). When compared to the non-treatment group, the local cold saline infusion treatment reduced both post-ischemic hyperperfusion (about 40%, P < 0·01) and delayed post-ischemic hypoperfusion (P < 0·01), improved functional neurological testing (P < 0·01), and reduced both cerebral infarction volume (40·6 ± 5·3 vs. 61·7 ± 8·6%, P < 0·01) and cerebral edema (7·8 ± 2·6 vs.15·4 ± 3·2%, P < 0·01). Conclusion: Cold saline, when infused directly into the ischemic brain region, can confer robust neuroprotection by reducing immediate post-ischemic hyperperfusion and delayed post-ischemic hypoperfusion.

A New Thrombosis Model of the Superior Sagittal Sinus Involving Cortical Veins

OBJECTIVE Patients with cerebral sinus and cortical venous thrombosis develop venous infarcts in approximately 50% of cases, resulting in serious clinical symptoms. An animal model is needed to further clarify the underlying mechanisms and consequences surrounding cerebral venous sinus thrombosis, particularly for severe ones. METHODS Adult male Sprague-Dawley rats were used to develop a new superior sagittal sinus thrombosis model involving cortical veins. The superior sagittal sinus was exposed and ligated. A microcatheter was inserted into the sinus, then both common carotid arteries were temporary occluded to reduce cerebral blood flow, and thrombin was injected into the sinus. Twenty-four hours later, after evaluating neurological function and obtaining a magnetic resonance imaging, animals were sacrificed and data pertaining to brain water content, infarct volume, and tissue histology was collected. RESULTS Superior sagittal sinus thrombosis and brain infarction were detected in all rats (100%). Hemorrhagic infarction, when present, and brain edema were observed in the brain parenchyma of the parietal lobe. The rate of hemorrhage was 59%, which is similar to that seen clinically in patients with superior sagittal sinus thrombosis. Brain edema, as measured by brain water content percentage, was significantly increased in thrombosed animals compared with sham-operated animals (80.8% ± 0.55% vs. 78.8% ± 0.14%, P < 0.05). Infarct volumes were 53.02 ± 7.91 mm(3). CONCLUSIONS We suggest that our modified model of superior sagittal sinus thrombosis, involving cortical veins, is suitable for the study of its underlying mechanisms, as well as therapeutic approaches directed at the disease.

Neuroprotective Mechanisms of Oxygen and Ethanol: A Potential Combination Therapy in Stroke

Currently, stroke researchers are racing to develop neuroprotective strategies that shield the brain from ischemia-induced injury. To date, neuroprotective agents that have shown promise in animal studies have failed in clinical trials. Since the pathophysiology of ischemic stroke exploits numerous pathways leading to cellular injury, a combination of neuroprotective agents may offer substantially better results than a single agent alone - by intervening in multiple mechanisms. In this paper, we consider an approach using combination therapy with normobaric oxygen (NBO) and ethanol. Studies indicate that NBO therapy improves tissue oxygenation, thereby reducing the extent of hypoxic injury and decelerating the development of tissue necrosis when administered early after stroke onset. Studies have also demonstrated that low to moderate levels of ethanol not only decrease the risk of stroke, but also reduce post-ischemic sequelae. This article reviews the history of NBO and ethanol therapies, their mechanisms of action, the results of key clinical trials, and the rationale for their use as a combination therapy in the context of stroke treatment.

Perfusion-based human cadaveric specimen as a simulation training model in repairing cerebrospinal fluid leaks during endoscopic endonasal skull base surgery

OBJECTIVE Competency in endoscopic endonasal approaches (EEAs) to repair high-flow cerebrospinal fluid (CSF) leaks is an essential component of the neurosurgical training process. The objective of this study was to demonstrate the feasibility of a simulation model for EEA repair of anterior skull base CSF leaks. METHODS Human cadaveric specimens were utilized with a perfusion system to simulate a high-flow CSF leak. Neurological surgery residents (postgraduate year 3 or greater) performed a standard EEA to repair a CSF leak using a combination of fat, fascia lata, and pedicled nasoseptal flaps. A standardized 5-point Likert questionnaire was used to assess the knowledge gained, techniques learned, degree of safety, benefit of CSF perfusion during repair, and pre- and posttraining confidence scores. RESULTS Intrathecal perfusion of fluorescein-infused saline into the ventricular/subarachnoid space was successful in 9 of 9 cases. The addition of CSF reconstitution offered the residents visual feedback for confirmation of intraoperative CSF leak repair. Residents gained new knowledge and a realistic simulation experience by rehearsing the psychomotor skills and techniques required to repair a CSF leak with fat and fascial grafts, as well as to prepare and rotate vascularized nasoseptal flaps. All trainees reported feeling safer with the procedure in a clinical setting and higher average posttraining confidence scores (pretraining 2.22 ± 0.83, posttraining 4.22 ± 0.44, p < 0.001). CONCLUSIONS Perfusion-based human cadaveric models can be utilized as a simulation training model for repairing CSF leaks during EEA.