Peg Forest Rehabilitation - A novel spatial navigation based cognitive rehabilitation paradigm for experimental neurotrauma.

Traumatic brain injury (TBI) results from mechanical forces applied to the head. Ensuing cascades of complex pathophysiology transition the injury event into a disease process. The enduring constellation of emotional, somatic, and cognitive impairments degrade quality of life for the millions of TBI survivors suffering from long-term neurological symptoms. Rehabilitation strategies have reported mixed results, as most have not focused on specific symptomatology or explored cellular processes. The current experiments evaluated a novel cognitive rehabilitation paradigm for brain-injured and uninjured rats. The arena is a plastic floor with a cartesian grid of holes for plastic dowels to create new environments with the rearrangement of threaded pegs. Rats received either two weeks of Peg Forest rehabilitation (PFR) or open field exposure starting at 7 days post-injury; or one week starting at either day 7 or 14 post-injury; or served as caged controls. Cognitive performance was assessed on a battery of novel object tasks at 28 days post-injury. The results revealed that two weeks of PFR was required to prevent the onset of cognitive impairments, while one week of PFR was insufficient regardless of when rehabilitation was initiated after injury. Further assessment of the task showed that novel daily arrangements of the environment were required to impart the cognitive performance benefits, as exposure to a static arrangement of pegs for PFR each day did not improve cognitive performance. The results indicate that PFR prevents the onset of cognitive disorders following acquired a mild to moderate brain injury, and potentially other neurological conditions.

Chronic Cognitive and Cerebrovascular Function after Mild Traumatic Brain Injury in Rats.

Severe traumatic brain injury (TBI) results in cognitive dysfunction in part due to vascular perturbations. In contrast, the long-term vasculo-cognitive pathophysiology of mild TBI (mTBI) remains unknown. We evaluated mTBI effects on chronic cognitive and cerebrovascular function and assessed their interrelationships. Sprague-Dawley rats received midline fluid percussion injury (n = 20) or sham (n = 21). Cognitive function was assessed (3- and 6-month novel object recognition [NOR], novel object location [NOL], and temporal order object recognition [TOR]). Six-month cerebral blood flow (CBF) and cerebral blood volume (CBV) using contrast magnetic resonance imaging (MRI) and ex vivo circle of Willis artery endothelial and smooth muscle-dependent function were measured. mTBI rats showed significantly impaired NOR, with similar trends (non-significant) in NOL/TOR. Regional CBF and CBV were similar in sham and mTBI. NOR correlated with CBF in lateral hippocampus, medial hippocampus, and primary somatosensory barrel cortex, whereas it inversely correlated with arterial smooth muscle-dependent dilation. Six-month baseline endothelial and smooth muscle-dependent arterial function were similar among mTBI and sham, but post-angiotensin 2 stimulation, mTBI showed no change in smooth muscle-dependent dilation from baseline response, unlike the reduction in sham. mTBI led to chronic cognitive dysfunction and altered angiotensin 2-stimulated smooth muscle-dependent vasoreactivity. The findings of persistent pathophysiological consequences of mTBI in this animal model add to the broader understanding of chronic pathophysiological sequelae in human mild TBI.

Nanoliposomes Reduce Stroke Injury Following Middle Cerebral Artery Occlusion in Mice.

BACKGROUND AND PURPOSE: Neuroprotective strategies for stroke remain inadequate. Nanoliposomes comprised of phosphatidylcholine, cholesterol, and monosialogangliosides (nanoliposomes) induced an antioxidant protective response in endothelial cells exposed to amyloid insults. We tested the hypotheses that nanoliposomes will preserve human neuroblastoma (SH-SY5Y) and human brain microvascular endothelial cells viability following oxygen-glucose deprivation (OGD)-reoxygenation and will reduce injury in mice following middle cerebral artery occlusion. METHODS: SH-SY5Y and human brain microvascular endothelial cells were exposed to oxygen-glucose deprivation-reoxygenation (3 hours 0.5%-1% oxygen and glucose-free media followed by 20-hour ambient air/regular media) without or with nanoliposomes (300 µg/mL). Viability was measured (calcein-acetoxymethyl fluorescence) and protein expression of antioxidant proteins HO-1 (heme oxygenase-1), NQO1 (NAD[P]H quinone dehydrogenase 1), and SOD1 (superoxide dismutase 1) were measured by Western blot. C57BL/6J mice were treated with saline (n=8) or nanoliposomes (10 mg/mL lipid, 200 µL, n=7) while undergoing 60-minute middle cerebral artery occlusion followed by reperfusion. Day 2 postinjury neurological impairment score and infarction size were compared. RESULTS: SH-SY5Y and human brain microvascular endothelial cells showed reduced viability post-oxygen-glucose deprivation-reoxygenation that was reversed by nanoliposomes. Nanoliposomes increased protein expressions of HO-1, NQO1 in both cell types and SOD1 in human brain microvascular endothelial cells. Nanoliposomes-treated mice showed reduced neurological impairment and brain infarct size (18.8±2% versus 27.3±2.3%, P=0.017) versus controls. CONCLUSIONS: Nanoliposomes reduced stroke injury in mice subjected to middle cerebral artery occlusion likely through induction of an antioxidant protective response. Nanoliposome is a candidate novel agent for stroke.

Extracellular matrix proteins are time-dependent and regional-specific markers in experimental diffuse brain injury.

INTRODUCTION: The extracellular matrix (ECM) provides structural support for neuronal, glial, and vascular components of the brain, and regulates intercellular signaling required for cellular morphogenesis, differentiation and homeostasis. We hypothesize that the pathophysiology of diffuse brain injury impacts the ECM in a multi-dimensional way across brain regions and over time, which could facilitate damage and repair processes. METHODS: Experimental diffuse TBI was induced in male Sprague-Dawley rats (325-375 g) by midline fluid percussion injury (FPI); uninjured sham rats serve as controls. Tissue from the cortex, thalamus, and hippocampus was collected at 15 min, 1, 2, 6, and 18 hr postinjury as well as 1, 3, 7, and 14 days postinjury. All samples were quantified by Western blot for glycoproteins: fibronectin, laminin, reelin, and tenascin-C. Band intensities were normalized to sham and relative to ß-actin. RESULTS: In the cortex, fibronectin decreased significantly at 15 min, 1 hr, and 2 hr postinjury, while tenascin-C decreased significantly at 7 and 14 days postinjury. In the thalamus, reelin decreased significantly at 2 hr, 3 and 14 days postinjury. In the hippocampus, tenascin-C increased significantly at 15 min and 7 days postinjury. CONCLUSION: Acute changes in the levels of these glycoproteins suggest involvement in circuit dismantling, whereas postacute levels may indicate a restorative or regenerative response associated with recovery from TBI.

Corrigendum: Experimental Traumatic Brain Injury Induces Chronic Glutamatergic Dysfunction in Amygdala Circuitry Known to Regulate Anxiety-Like Behavior.

[This corrects the article DOI: 10.3389/fnins.2019.01434.].

Experimental Traumatic Brain Injury Induces Chronic Glutamatergic Dysfunction in Amygdala Circuitry Known to Regulate Anxiety-Like Behavior.

Up to 50% of traumatic brain injury (TBI) survivors demonstrate persisting and late-onset anxiety disorders indicative of limbic system dysregulation, yet the pathophysiology underlying the symptoms is unclear. We hypothesize that the development of TBI-induced anxiety-like behavior in an experimental model of TBI is mediated by changes in glutamate neurotransmission within the amygdala. Adult, male Sprague-Dawley rats underwent midline fluid percussion injury or sham surgery. Anxiety-like behavior was assessed at 7 and 28 days post-injury (DPI) followed by assessment of real-time glutamate neurotransmission in the basolateral amygdala (BLA) and central nucleus of the amygdala (CeA) using glutamate-selective microelectrode arrays. The expression of anxiety-like behavior at 28 DPI coincided with decreased evoked glutamate release and slower glutamate clearance in the CeA, not BLA. Numerous factors contribute to the changes in glutamate neurotransmission over time. In two additional animal cohorts, protein levels of glutamatergic transporters (Glt-1 and GLAST) and presynaptic modulators of glutamate release (mGluR2, TrkB, BDNF, and glucocorticoid receptors) were quantified using automated capillary western techniques at 28 DPI. Astrocytosis and microglial activation have been shown to drive maladaptive glutamate signaling and were histologically assessed over 28 DPI. Alterations in glutamate neurotransmission could not be explained by changes in protein levels for glutamate transporters, mGluR2 receptors, astrocytosis, and microglial activation. Presynaptic modulators, BDNF and TrkB, were significantly decreased at 28 DPI in the amygdala. Dysfunction in presynaptic regulation of glutamate neurotransmission may contribute to anxiety-related behavior and serve as a therapeutic target to improve circuit function.

Mutualistic interaction between dichloromethane- and chloromethane-degrading bacteria in an anaerobic mixed culture.

The microbial mixed culture RM grows with dichloromethane (DCM) as the sole energy source generating acetate, methane, chloride and biomass as products. Chloromethane (CM) was not an intermediate during DCM utilization consistent with the observation that CM could not replace DCM as a growth substrate. Interestingly, cultures that received DCM and CM together degraded both compounds concomitantly. Transient hydrogen (H2 ) formation reaching a maximum concentration of 205 ± 13 ppmv was observed in cultures growing with DCM, and the addition of exogenous H2 at concentrations exceeding 3000 ppmv impeded DCM degradation. In contrast, CM degradation in culture RM had a strict requirement for H2 . Following five consecutive transfers on CM and H2 , Acetobacterium 16S rRNA gene sequences dominated the culture and the DCM-degrader Candidatus Dichloromethanomonas elyunquensis was eliminated, consistent with the observation that the culture lost the ability to degrade DCM. These findings demonstrate that culture RM harbours different populations responsible for anaerobic DCM and CM metabolism, and further imply that the DCM and CM degradation pathways are mechanistically distinct. H2 generated during DCM degradation is consumed by the hydrogenotrophic CM degrader, or may fuel other hydrogenotrophic processes, including organohalide respiration, methanogenesis and H2 /CO2 reductive acetogenesis.

Clinical relevance of midline fluid percussion brain injury: Acute deficits, chronic morbidities and the utility of biomarkers.

BACKGROUND: After 30 years of characterisation and implementation, fluid percussion injury (FPI) is firmly recognised as one of the best-characterised reproducible and clinically relevant models of TBI, encompassing concussion through diffuse axonal injury (DAI). Depending on the specific injury parameters (e.g. injury site, mechanical force), FPI can model diffuse TBI with or without a focal component and may be designated as mild-to-severe according to the chosen mechanical forces and resulting acute neurological responses. Among FPI models, midline FPI may best represent clinical diffuse TBI, because of the acute behavioural deficits, the transition to late-onset behavioural morbidities and the absence of gross histopathology. REVIEW: The goal here was to review acute and chronic physiological and behavioural deficits and morbidities associated with diffuse TBI induced by midline FPI. In the absence of neurodegenerative sequelae associated with focal injury, there is a need for biomarkers in the diagnostic, prognostic, predictive and therapeutic approaches to evaluate outcomes from TBI. CONCLUSIONS: The current literature suggests that midline FPI offers a clinically-relevant, validated model of diffuse TBI to investigators wishing to evaluate novel therapeutic strategies in the treatment of TBI and the utility of biomarkers in the delivery of healthcare to patients with brain injury.

Midline (Central) Fluid Percussion Model of Traumatic Brain Injury.

Research models of traumatic brain injury (TBI) hold significant validity towards the human condition, with each model replicating a subset of clinical features and symptoms. After 30 years of characterization and implementation, fluid percussion injury (FPI) is firmly recognized as a clinically relevant model of TBI, encompassing concussion through severe injury. The midline variation of FPI may best represent mild and diffuse clinical brain injury, because of the acute behavioral deficits, the late onset of subtle behavioral morbidities, and the absence of gross histopathology. This chapter outlines the procedures for midline (diffuse) FPI in adult male rats and mice. With these procedures, it becomes possible to generate brain-injured laboratory animals for studies of injury-induced pathophysiology and behavioral deficits, for which rational therapeutic interventions can be implemented.

Bioaugmentation with distinct Dehalobacter strains achieves chloroform detoxification in microcosms.

Chloroform (CF) is a widespread groundwater contaminant not susceptible to aerobic degradation. Under anoxic conditions, CF can undergo abiotic and cometabolic transformation but detoxification is generally not achieved. The recent discovery of distinct Dehalobacter strains that respire CF to dichloromethane (DCM) and ferment DCM to nonchlorinated products promises that bioremediation of CF plumes is feasible. To track both strains, 16S rRNA gene-based qPCR assays specific for either Dehalobacter strain were designed and validated. A laboratory treatability study explored the value of bioaugmentation and biostimulation to achieve CF detoxification using anoxic microcosms established with aquifer material from a CF-contaminated site. Microcosms that received 6% (v/v) of the CF-to-DCM-dechlorinating culture Dhb-CF to achieve an initial Dehalobacter cell titer of 1.6 ± 0.9 × 10(4) mL(-1) dechlorinated CF to stoichiometric amounts of DCM. Subsequent augmentation with 3% (v/v) of the DCM-degrading consortium RM to an initial Dehalobacter cell abundance of 1.2 ± 0.2 × 10(2) mL(-1) achieved complete DCM degradation in microcosms amended with 10 mM bicarbonate. Growth of the CF-respiring and the DCM-degrading Dehalobacter populations and detoxification were also observed in microcosms that received both inocula simultaneously. These findings suggest that anaerobic bioremediation (e.g., bioaugmentation) is a possible remedy at CF- and DCM-contaminated sites without CT, which strongly inhibited CF organohalide respiration and DCM organohalide fermentation.