Noel Casey

Chronic Traumatic Encephalopathy in Blast-Exposed Military Veterans and a Blast Neurotrauma Mouse Model

Blast exposure is associated with chronic traumatic encephalopathy, impaired neuronal function, and persistent cognitive deficits in blast-exposed military veterans and experimental animals. Blast Brain: An Invisible Injury Revealed Traumatic brain injury (TBI) is the “signature” injury of the conflicts in Afghanistan and Iraq and is associated with psychiatric symptoms and long-term cognitive disability. Recent estimates indicate that TBI may affect 20% of the 2.3 million U.S. servicemen and women deployed since 2001. Chronic traumatic encephalopathy (CTE), a tau protein–linked neurodegenerative disorder reported in athletes with multiple concussions, shares clinical features with TBI in military personnel exposed to explosive blast. However, the connection between TBI and CTE has not been explored in depth. In a new study, Goldstein et al. investigate this connection in the first case series of postmortem brains from U.S. military veterans with blast exposure and/or concussive injury. They report evidence for CTE neuropathology in the military veteran brains that is similar to that observed in the brains of young amateur American football players and a professional wrestler. The investigators developed a mouse model of blast neurotrauma that mimics typical blast conditions associated with military blast injury and discovered that blast-exposed mice also demonstrate CTE neuropathology, including tau protein hyperphosphorylation, myelinated axonopathy, microvascular damage, chronic neuroinflammation, and neurodegeneration. Surprisingly, blast-exposed mice developed CTE neuropathology within 2 weeks after exposure to a single blast. In addition, the neuropathology was accompanied by functional deficits, including slowed axonal conduction, reduced activity-dependent long-term synaptic plasticity, and impaired spatial learning and memory that persisted for 1 month after exposure to a single blast. The investigators then showed that blast winds with velocities of more than 330 miles/hour—greater than the most intense wind gust ever recorded on earth—induced oscillating head acceleration of sufficient intensity to injure the brain. The researchers then demonstrated that blast-induced learning and memory deficits in the mice were reduced by immobilizing the head during blast exposure. These findings provide a direct connection between blast TBI and CTE and indicate a primary role for blast wind–induced head acceleration in blast-related neurotrauma and its aftermath. This study also validates a new blast neurotrauma mouse model that will be useful for developing new diagnostics, therapeutics, and rehabilitative strategies for treating blast-related TBI and CTE. Blast exposure is associated with traumatic brain injury (TBI), neuropsychiatric symptoms, and long-term cognitive disability. We examined a case series of postmortem brains from U.S. military veterans exposed to blast and/or concussive injury. We found evidence of chronic traumatic encephalopathy (CTE), a tau protein–linked neurodegenerative disease, that was similar to the CTE neuropathology observed in young amateur American football players and a professional wrestler with histories of concussive injuries. We developed a blast neurotrauma mouse model that recapitulated CTE-linked neuropathology in wild-type C57BL/6 mice 2 weeks after exposure to a single blast. Blast-exposed mice demonstrated phosphorylated tauopathy, myelinated axonopathy, microvasculopathy, chronic neuroinflammation, and neurodegeneration in the absence of macroscopic tissue damage or hemorrhage. Blast exposure induced persistent hippocampal-dependent learning and memory deficits that persisted for at least 1 month and correlated with impaired axonal conduction and defective activity-dependent long-term potentiation of synaptic transmission. Intracerebral pressure recordings demonstrated that shock waves traversed the mouse brain with minimal change and without thoracic contributions. Kinematic analysis revealed blast-induced head oscillation at accelerations sufficient to cause brain injury. Head immobilization during blast exposure prevented blast-induced learning and memory deficits. The contribution of blast wind to injurious head acceleration may be a primary injury mechanism leading to blast-related TBI and CTE. These results identify common pathogenic determinants leading to CTE in blast-exposed military veterans and head-injured athletes and additionally provide mechanistic evidence linking blast exposure to persistent impairments in neurophysiological function, learning, and memory.

The Zinc Dyshomeostasis Hypothesis of Alzheimer's Disease

Alzheimers disease (AD) is the most common form of dementia in the elderly. Hallmark AD neuropathology includes extracellular amyloid plaques composed largely of the amyloid-β protein (Aβ), intracellular neurofibrillary tangles (NFTs) composed of hyper-phosphorylated microtubule-associated protein tau (MAP-tau), and microtubule destabilization. Early-onset autosomal dominant AD genes are associated with excessive Aβ accumulation, however cognitive impairment best correlates with NFTs and disrupted microtubules. The mechanisms linking Aβ and NFT pathologies in AD are unknown. Here, we propose that sequestration of zinc by Aβ-amyloid deposits (Aβ oligomers and plaques) not only drives Aβ aggregation, but also disrupts zinc homeostasis in zinc-enriched brain regions important for memory and vulnerable to AD pathology, resulting in intra-neuronal zinc levels, which are either too low, or excessively high. To evaluate this hypothesis, we 1) used molecular modeling of zinc binding to the microtubule component protein tubulin, identifying specific, high-affinity zinc binding sites that influence side-to-side tubulin interaction, the sensitive link in microtubule polymerization and stability. We also 2) performed kinetic modeling showing zinc distribution in extra-neuronal Aβ deposits can reduce intra-neuronal zinc binding to microtubules, destabilizing microtubules. Finally, we 3) used metallomic imaging mass spectrometry (MIMS) to show anatomically-localized and age-dependent zinc dyshomeostasis in specific brain regions of Tg2576 transgenic, mice, a model for AD. We found excess zinc in brain regions associated with memory processing and NFT pathology. Overall, we present a theoretical framework and support for a new theory of AD linking extra-neuronal Aβ amyloid to intra-neuronal NFTs and cognitive dysfunction. The connection, we propose, is based on β-amyloid-induced alterations in zinc ion concentration inside neurons affecting stability of polymerized microtubules, their binding to MAP-tau, and molecular dynamics involved in cognition. Further, our theory supports novel AD therapeutic strategies targeting intra-neuronal zinc homeostasis and microtubule dynamics to prevent neurodegeneration and cognitive decline.

Concussion, microvascular injury, and early tauopathy in young athletes after impact head injury and an impact concussion mouse model

The mechanisms underpinning concussion, traumatic brain injury (TBI) and chronic traumatic encephalopathy (CTE) are poorly understood. Using neuropathological analyses of brains from teenage athletes, a new mouse model of concussive impact injury, and computational simulations, Tagge et al. show that head injuries can induce TBI and early CTE pathologies independent of concussion.

Demand for Zn2+ in Acid-Secreting Gastric Mucosa and Its Requirement for Intracellular Ca2+

Background and Aims Recent work has suggested that Zn2+ plays a critical role in regulating acidity within the secretory compartments of isolated gastric glands. Here, we investigate the content, distribution and demand for Zn2+ in gastric mucosa under baseline conditions and its regulation during secretory stimulation. Methods and Findings Content and distribution of zinc were evaluated in sections of whole gastric mucosa using X-ray fluorescence microscopy. Significant stores of Zn2+ were identified in neural elements of the muscularis, glandular areas enriched in parietal cells, and apical regions of the surface epithelium. In in vivo studies, extraction of the low abundance isotope, 70Zn2+, from the circulation was demonstrated in samples of mucosal tissue 24 hours or 72 hours after infusion (250 µg/kg). In in vitro studies, uptake of 70Zn2+ from media was demonstrated in isolated rabbit gastric glands following exposure to concentrations as low as 10 nM. In additional studies, demand of individual gastric parietal cells for Zn2+ was monitored using the fluorescent zinc reporter, fluozin-3, by measuring increases in free intracellular concentrations of Zn2+ {[Zn2+]i} during exposure to standard extracellular concentrations of Zn2+ (10 µM) for standard intervals of time. Under resting conditions, demand for extracellular Zn2+ increased with exposure to secretagogues (forskolin, carbachol/histamine) and under conditions associated with increased intracellular Ca2+ {[Ca2+]i}. Uptake of Zn2+ was abolished following removal of extracellular Ca2+ or depletion of intracellular Ca2+ stores, suggesting that demand for extracellular Zn2+ increases and depends on influx of extracellular Ca2+. Conclusions This study is the first to characterize the content and distribution of Zn2+ in an organ of the gastrointestinal tract. Our findings offer the novel interpretation, that Ca2+ integrates basolateral demand for Zn2+ with stimulation of secretion of HCl into the lumen of the gastric gland. Similar connections may be detectable in other secretory cells and tissues.

CONCUSSION, MICROVASCULAR INJURY, AND EARLY TAUOPATHY IN YOUNG ATHLETES AFTER IMPACT HEAD INJURY AND AN IMPACT CONCUSSION MOUSE MODEL

tauopathy in young athletes after impact head injury and an impact concussion mouse model 5 Chad A. Tagge,* Andrew M. Fisher,* Olga V. Minaeva,* Amanda GaudreauBalderrama, Juliet A. Moncaster, Xiao-Lei Zhang, Mark W. Wojnarowicz, Noel Casey, Haiyan Lu, Olga N. Kokiko-Cochran, Sudad Saman, Maria Ericsson, Kristen D. Onos, Ronel Veksler, Vladimir V. Senatorov, Jr, Asami Kondo, Xiao Z. Zhou, Omid Miry, Linnea R. Vose, Katisha R. Gopaul, Chirag Upreti, 10 Christopher J. Nowinski, Robert C. Cantu, Victor E. Alvarez, Audrey M. Hildebrandt, Erich S. Franz, Janusz Konrad, James A. Hamilton, Ning Hua, Yorghos Tripodis, Andrew T. Anderson, Gareth R. Howell, Daniela Kaufer, Garth F. Hall, Kun P. Lu, Richard M. Ransohoff,7,z Robin O. Cleveland, Neil W. Kowall, Thor D. Stein, Bruce T. Lamb, Bertrand R. Huber, 15 William C. Moss, Alon Friedman, Patric K. Stanton, Ann C. McKee, Lee E. Goldstein

Mechanistic pathobiology of acute concussion, traumatic brain injury, and chronic traumatic encephalopathy in mouse models of blast neurotrauma and impact concussion

(active form), while had no effect on the level of Tyrosine-307phosphorylated PP-2A. Unexpectedly, 5-HT1A agonist 8-OHDPAT did not decrease forskolin-induced tau hyperphophorylation. Conclusions:Escitalopram could protect forskolin-induced tau hyperphosphorylation at multiple AD-related sites, and the mechanism involves inactivation of GSK-3b. Our findings suggest that escitalopram could be a promising therapeutic target for AD-like tau hyperphosphorylation, this may support a potential effective role of antidepressants, at least of the SSRI class, in the prevention of dementia associated with depression in patients.

Noninvasive detection of Alzheimer's disease Aβ pathology in the lenses of human subjects with Down syndrome

we have been manually counting diffuse Aß plaques (DPs), neuritic Aß plaques (NPs), and neurofibrillary tangles (NFTs) in multiple brain sections for every patient in our neuropathologic database for over 20 years. Such counting, however, is time consuming and involves technical challenges. To minimize these sources of experimental bias and to standardize our database, we wanted to develop computer based algorithms that exploit the advantages of digital pathology and advanced image analysis software. Methods: We examined cases from the UK-ADC database including brains with AD pathological severity ranging from normal controls to end-stage AD. In our initial sample we analyzed a total of 54 cases, from which portions of superior and middle temporal gyri (SMTG) were selected and stained with both Aß and PHF-1 antibodies. The slides were then scanned using the Aperio ScanScope XT at a 40x magnification. For amyloid quantitation, two parameters were calculated: a DP density and an overall amyloid burden, using modified algorithms from the Aperio Image Analysis Toolbox , respectively. To quantitate NPs and NFTs, we first utilized the Genie Histology Pattern Recognition software to ‘teach’ the computer to identify these structures.We then used a modified positive pixel count to calculate NP burden and a modified nuclear algorithm to calculate NFT density. Results: We found good correlation between our recorded manual counts and the amyloid burden, DP density, and NFT density. We also found good correlation between NP burden and our manual counts, however such studies were somewhat confounded by the differences between the modified Bielschowsky silver stain and the PHF-1 immunohistochemical stain. Conclusions: Image analysis, using our modified algorithms, offers a more efficient and replicable, and less-biased method, relative to manual counting.

Metallomic imaging mass and optical spectrometry (MIMOS) of the murine and human eye and brain in Alzheimer's disease and normal aging

correlation using conventional and advanced mri imaging techniques in differentiating the subtypes of progressive supranuclear palsy (PSP) i.e psp-p and psp richardson subtypes. Methods: This was a prospective study comprising of 24 patients of PSP (psp P 1⁄4 11 and psp-rs1⁄4 13) and 26 matched healthy controls. routine mri imaging and planimetry were used to diffrentiate.VBM analysis for both gray matter with t1 weighted image and white matter using DTI was performed.advanced TBSS analysis was also perfrmed and Fractionalanisotropy, mean diffusivity (MD), axial diffusivity, andradial diffusivity (RD) changes were studied in theWM of these PSP patients to identify relative severity of WM changes as well as identify spatial distribution of the differences. Clinicoradiological correlation was done to determine the strength of correlation between WM abnormalities.minerlarisation was also evaluated used r2 relaxometry. Results: The frontoparietal cerebral WM, thalamus, midbrain tectum,superior cerebellar peduncle, and cerebellar WM showed significant abnomality. Compared to PSP-P, the patients of PSP-RS had more spatial abnormalities localized to the frontal WM. Conclusions: PSP-RS showed more severe white matter abnormality compared to the PSP-P subtype.

High-resolution multi-elemental metallomic mapping of the human eye in Alzheimer's disease and normal aging

Background:We previously identified amyloid-b (Ab) deposition, amyloid pathology, and co-localizing supranuclear cataracts in the lens of the eye in Alzheimer’s disease (AD) and Down Syndrome (DS) [Goldstein, 2003; Moncaster, 2010]. Interaction of Ab and biometals represents a major pathogenic pathway in AD and provides the basis for clinical effective disease-modifying therapy (Duce and Bush, 2010; Lannfelt, 2008). To date, mapping the ocular metallome has been limited by technical barriers. Here we developed a new technique, High-Resolution Metallomic Imaging Mass Spectrometry (HR-MIMS), to perform the first high-resolution multielemental and isotopic distribution maps of the metallome of the adult human eye in AD and age-matched controls. Methods: Human eyes were obtained through the Boston University Alzheimer’s Disease Center and NDRI (Philadelphia, PA). Eyes were flash frozen and analyzed by metallomic imagingmass spectrometry (MIMSmapping) using a custom cryogenic cell coupled to nanosecond ultraviolet laser ablation (NULA) and hyphenated high-resolution magnetic sector field ICP-MS at the Boston University Center for Biometals & Metallomics, Boston, MA. Laser wavelength, 213 nm; rate, 5-50 mms-1; spot size: 10 micron (high resolution) to 100 micron (scanning resolution). MIMS analysis was conducted on surround to establish elemental background and calibrated with NIST standards. Results: High resolutionmetallomic maps generated fromAD and age-matched control eyes demonstrated unique elemental and isotopic distribution patterns. Zinc was confirmed in the subequatorial supranucleus of the lens, the same region implicated in AD-linked Ab accumulation and cataractogenesis. Retinal zinc demonstrated a laminar distribution corresponding to cytoarchitectonic organization. Retinal iron revealed a vascular distribution pattern. Simultaneous metallomic maps of the same lenses revealed distinctive elemental and isotopic distribution patterns for other important biometals, including copper (Cu), iron (Fe), selenium (Se), molybdenum (Mo), manganese (Mn), and other elements. Conclusions: We deployed HR-MIMS analysis to generate detailed quantitative high-resolution spatial distribution maps of essential and trace elements and isotopes in adult human eyes in AD and age-matched controls at 10-100 micron spatial resolution. This study strongly supports a role for zinc in AD-linked lens pathology.

Involvement of metals in Aβ aggregation in Alzheimer's disease brain and lens using X-ray Fluorescent Microscopy (XRFM) and Quasi-Elastic Light Scattering (QLS)

enriched tau proteins from the control and transgenic mice were immunoprecipitated with a monoclonal antibody against tau. The immuno-precipitants were then digested with trypsin. The phosphorylated peptides in the control and transgenic mouse samples were enriched once again by the CHT-based method. The phosphopeptides were then analyzed by MALDI-TOF mass spectrometry and the peptide mass profiles of tau protein were compared between the age-matched wild type and transgenic animals to examine the changes in tau protein phosphorylation. Conclusions: Our study demonstrated that CHT-based fractionation is an easy-to-use, fast and convenient method for phosphoprotein/peptide enrichment with high binding capacity. It could potentially be used to enrich highly-phophorylated proteins and facilitate the biochemical study of hyperphosphorylated tau in Alzheimer’s disease.