1
|
Stone JR, Avants BB, Tustison NJ, Gill J, Wilde EA, Neumann KD, Gladney LA, Kilgore MO, Bowling F, Wilson CM, Detro JF, Belanger HG, Deary K, Linsenbardt H, Ahlers ST. Neurological Effects of Repeated Blast Exposure in Special Operations Personnel. J Neurotrauma 2024; 41:942-956. [PMID: 37950709 PMCID: PMC11001960 DOI: 10.1089/neu.2023.0309] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2023] Open
Abstract
Exposure to blast overpressure has been a pervasive feature of combat-related injuries. Studies exploring the neurological correlates of repeated low-level blast exposure in career "breachers" demonstrated higher levels of tumor necrosis factor alpha (TNFα) and interleukin (IL)-6 and decreases in IL-10 within brain-derived extracellular vesicles (BDEVs). The current pilot study was initiated in partnership with the U.S. Special Operations Command (USSOCOM) to explore whether neuroinflammation is seen within special operators with prior blast exposure. Data were analyzed from 18 service members (SMs), inclusive of 9 blast-exposed special operators with an extensive career history of repeated blast exposures and 9 controls matched by age and duration of service. Neuroinflammation was assessed utilizing positron emission tomography (PET) imaging with [18F]DPA-714. Serum was acquired to assess inflammatory biomarkers within whole serum and BDEVs. The Blast Exposure Threshold Survey (BETS) was acquired to determine blast history. Both self-report and neurocognitive measures were acquired to assess cognition. Similarity-driven Multi-view Linear Reconstruction (SiMLR) was used for joint analysis of acquired data. Analysis of BDEVs indicated significant positive associations with a generalized blast exposure value (GBEV) derived from the BETS. SiMLR-based analyses of neuroimaging demonstrated exposure-related relationships between GBEV, PET-neuroinflammation, cortical thickness, and volume loss within special operators. Affected brain networks included regions associated with memory retrieval and executive functioning, as well as visual and heteromodal processing. Post hoc assessments of cognitive measures failed to demonstrate significant associations with GBEV. This emerging evidence suggests neuroinflammation may be a key feature of the brain response to blast exposure over a career in operational personnel. The common thread of neuroinflammation observed in blast-exposed populations requires further study.
Collapse
Affiliation(s)
- James R. Stone
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - Brian B. Avants
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - Nicholas J. Tustison
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - Jessica Gill
- School of Nursing, Johns Hopkins University, Baltimore, Maryland, USA
| | - Elisabeth A. Wilde
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
- George E. Wahlen VA, Salt Lake City Health Healthcare System, Salt Lake City, Utah, USA
| | - Kiel D. Neumann
- Molecular Imaging Research Hub, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Leslie A. Gladney
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - Madison O. Kilgore
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - F. Bowling
- U.S. Special Operations Command, Tampa, Florida, USA
| | | | - John F. Detro
- U.S. Special Operations Command, Tampa, Florida, USA
| | - Heather G. Belanger
- Departments of Psychiatry and Behavioral Neurosciences, and Psychology, University of South Florida, Tampa, Florida, USA
- Cognitive Research Corporation, St. Petersburg, Florida, USA
| | - Katryna Deary
- U.S. Special Operations Command, Tampa, Florida, USA
| | | | - Stephen T. Ahlers
- Operational and Undersea Medicine Directorate, Naval Medical Research Command, Silver Spring, Maryland, USA
| |
Collapse
|
2
|
Sachdeva T, Ganpule SG. Twenty Years of Blast-Induced Neurotrauma: Current State of Knowledge. Neurotrauma Rep 2024; 5:243-253. [PMID: 38515548 PMCID: PMC10956535 DOI: 10.1089/neur.2024.0001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024] Open
Abstract
Blast-induced neurotrauma (BINT) is an important injury paradigm of neurotrauma research. This short communication summarizes the current knowledge of BINT. We divide the BINT research into several broad categories-blast wave generation in laboratory, biomechanics, pathology, behavioral outcomes, repetitive blast in animal models, and clinical and neuroimaging investigations in humans. Publications from 2000 to 2023 in each subdomain were considered. The analysis of the literature has brought out salient aspects. Primary blast waves can be simulated reasonably in a laboratory using carefully designed shock tubes. Various biomechanics-based theories of BINT have been proposed; each of these theories may contribute to BINT by generating a unique biomechanical signature. The injury thresholds for BINT are in the nascent stages. Thresholds for rodents are reasonably established, but such thresholds (guided by primary blast data) are unavailable in humans. Single blast exposure animal studies suggest dose-dependent neuronal pathologies predominantly initiated by blood-brain barrier permeability and oxidative stress. The pathologies were typically reversible, with dose-dependent recovery times. Behavioral changes in animals include anxiety, auditory and recognition memory deficits, and fear conditioning. The repetitive blast exposure manifests similar pathologies in animals, however, at lower blast overpressures. White matter irregularities and cortical volume and thickness alterations have been observed in neuroimaging investigations of military personnel exposed to blast. Behavioral changes in human cohorts include sleep disorders, poor motor skills, cognitive dysfunction, depression, and anxiety. Overall, this article provides a concise synopsis of current understanding, consensus, controversies, and potential future directions.
Collapse
Affiliation(s)
- Tarun Sachdeva
- Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee, India
| | - Shailesh G. Ganpule
- Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee, India
- Department of Design, Indian Institute of Technology Roorkee, Roorkee, India
| |
Collapse
|
3
|
Green TRF, Carey SD, Mannino G, Craig JA, Rowe RK, Zielinski MR. Sleep, inflammation, and hemodynamics in rodent models of traumatic brain injury. Front Neurosci 2024; 18:1361014. [PMID: 38426017 PMCID: PMC10903352 DOI: 10.3389/fnins.2024.1361014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Accepted: 01/29/2024] [Indexed: 03/02/2024] Open
Abstract
Traumatic brain injury (TBI) can induce dysregulation of sleep. Sleep disturbances include hypersomnia and hyposomnia, sleep fragmentation, difficulty falling asleep, and altered electroencephalograms. TBI results in inflammation and altered hemodynamics, such as changes in blood brain barrier permeability and cerebral blood flow. Both inflammation and altered hemodynamics, which are known sleep regulators, contribute to sleep impairments post-TBI. TBIs are heterogenous in cause and biomechanics, which leads to different molecular and symptomatic outcomes. Animal models of TBI have been developed to model the heterogeneity of TBIs observed in the clinic. This review discusses the intricate relationship between sleep, inflammation, and hemodynamics in pre-clinical rodent models of TBI.
Collapse
Affiliation(s)
- Tabitha R. F. Green
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, United States
| | - Sean D. Carey
- Veterans Affairs (VA) Boston Healthcare System, West Roxbury, MA, United States
- Department of Psychiatry, Harvard Medical School, West Roxbury, MA, United States
| | - Grant Mannino
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, United States
| | - John A. Craig
- Veterans Affairs (VA) Boston Healthcare System, West Roxbury, MA, United States
| | - Rachel K. Rowe
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, United States
| | - Mark R. Zielinski
- Veterans Affairs (VA) Boston Healthcare System, West Roxbury, MA, United States
- Department of Psychiatry, Harvard Medical School, West Roxbury, MA, United States
| |
Collapse
|
4
|
Gama Sosa MA, De Gasperi R, Pryor D, Perez Garcia GS, Perez GM, Abutarboush R, Kawoos U, Hogg S, Ache B, Sowa A, Tetreault T, Varghese M, Cook DG, Zhu CW, Tappan SJ, Janssen WGM, Hof PR, Ahlers ST, Elder GA. Late chronic local inflammation, synaptic alterations, vascular remodeling and arteriovenous malformations in the brains of male rats exposed to repetitive low-level blast overpressures. Acta Neuropathol Commun 2023; 11:81. [PMID: 37173747 PMCID: PMC10176873 DOI: 10.1186/s40478-023-01553-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 03/16/2023] [Indexed: 05/15/2023] Open
Abstract
In the course of military operations in modern war theaters, blast exposures are associated with the development of a variety of mental health disorders associated with a post-traumatic stress disorder-related features, including anxiety, impulsivity, insomnia, suicidality, depression, and cognitive decline. Several lines of evidence indicate that acute and chronic cerebral vascular alterations are involved in the development of these blast-induced neuropsychiatric changes. In the present study, we investigated late occurring neuropathological events associated with cerebrovascular alterations in a rat model of repetitive low-level blast-exposures (3 × 74.5 kPa). The observed events included hippocampal hypoperfusion associated with late-onset inflammation, vascular extracellular matrix degeneration, synaptic structural changes and neuronal loss. We also demonstrate that arteriovenous malformations in exposed animals are a direct consequence of blast-induced tissue tears. Overall, our results further identify the cerebral vasculature as a main target for blast-induced damage and support the urgent need to develop early therapeutic approaches for the prevention of blast-induced late-onset neurovascular degenerative processes.
Collapse
Affiliation(s)
- Miguel A Gama Sosa
- General Medical Research Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY, 10468, USA.
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY, 10029, USA.
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
| | - Rita De Gasperi
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY, 10468, USA
| | - Dylan Pryor
- Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY, 10468, USA
| | - Georgina S Perez Garcia
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY, 10468, USA
- Department of Neurology, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY, 10029, USA
| | - Gissel M Perez
- Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY, 10468, USA
| | - Rania Abutarboush
- Department of Neurotrauma, Operational and Undersea Medicine Directorate, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, USA
| | - Usmah Kawoos
- Department of Neurotrauma, Operational and Undersea Medicine Directorate, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, USA
| | - Seth Hogg
- Micro Photonics, Inc, 1550 Pond Road, Suite 110, Allentown, PA, 18104, USA
| | - Benjamin Ache
- Micro Photonics, Inc, 1550 Pond Road, Suite 110, Allentown, PA, 18104, USA
| | - Allison Sowa
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | | | - Merina Varghese
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - David G Cook
- Geriatric Research Education and Clinical Center, VA Puget Sound Health Care System, 1660 S Columbian Way, Seattle, WA, 98108, USA
- Department of Medicine, University of Washington, 1959 NE Pacific St, Seattle, WA, 98195, USA
| | - Carolyn W Zhu
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY, 10029, USA
- Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY, 10468, USA
- Mount Sinai Alzheimer's Disease Research Center and the Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Susan J Tappan
- MBF Bioscience LLC, 185 Allen Brook Lane, Williston, VT, 05495, USA
| | - William G M Janssen
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Patrick R Hof
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Mount Sinai Alzheimer's Disease Research Center and the Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Department of Geriatrics and Palliative Care, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Stephen T Ahlers
- Department of Neurotrauma, Operational and Undersea Medicine Directorate, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Gregory A Elder
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Department of Neurology, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY, 10029, USA
- Mount Sinai Alzheimer's Disease Research Center and the Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Neurology Service, James J. Peters Department of Veterans Affairs Medical Center, 130 West Kingsbridge Road, Bronx, NY, 10468, USA
| |
Collapse
|
5
|
Cralley AL, Moore EE, Fox CJ, Kissau D, DeBot M, Schaid TR, Mitra S, Hom P, Fragoso M, Ghasabyan A, Erickson C, D'Alessandro A, Hansen KC, Cohen MJ, Silliman CC, Sauaia A. Zone 1 REBOA in a combat DCBI swine model does not worsen brain injury. Surgery 2022; 172:751-758. [PMID: 35690490 PMCID: PMC9675949 DOI: 10.1016/j.surg.2022.04.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/01/2022] [Accepted: 04/29/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND Zone 1 resuscitative endovascular balloon occlusion of the aorta has been recommended for refractory shock after a dismounted complex blast injury for the austere combat scenario. While resuscitative endovascular balloon occlusion of the aorta should enhance coronary perfusion, there is a potential risk of secondary brain injury due to loss of cerebral autoregulation. We developed a combat casualty relevant dismounted complex blast injury swine model to evaluate the effects of resuscitative endovascular balloon occlusion of the aorta zone I on intracranial pressure and cerebral edema. We hypothesized that zone 1 aortic occlusion with resuscitative endovascular balloon occlusion of the aorta would increase mean arterial pressure transmitted in excessive intracranial pressure, thereby worsening brain injury. METHODS 50 kg male Yorkshire swine were subjected to a combination dismounted complex blast injury model consisting of blast traumatic brain injury (50 psi, ARA Mobile Shock Laboratory), tissue injury (bilateral femur fractures), and hemorrhagic shock (controlled bleeding to a base deficit goal of 10 mEq/L). During the shock phase, pigs were randomized to no aortic occlusion (n = 8) or to 30 minutes of zone 1 resuscitative endovascular balloon occlusion of the aorta (zone 1 aortic occlusion group, n = 6). After shock, pigs in both groups received a modified Tactical Combat Casualty Care-based resuscitation and were monitored for an additional 240 minutes until euthanasia/death for a total of 6 hours. Intracranial pressure was monitored throughout, and brains were harvested for water content. Linear mixed models for repeated measures were used to compare mean arterial pressure and intracranial pressure between zone 1 aortic occlusion and no aortic occlusion groups. RESULTS After dismounted complex blast injury, the zone 1 group had a significantly higher mean arterial pressure during hemorrhagic shock compared to the control group (41.2 mm Hg vs 16.7 mm Hg, P = .002). During balloon occlusion, intracranial pressure was not significantly elevated in the zone 1 aortic occlusion group vs control, but intracranial pressure was significantly lower in the zone 1 group at the end of the observation period. In addition, the zone 1 aortic occlusion group did not have increased brain water content (zone 1 aortic occlusion: 3.95 ± 0.1g vs no aortic occlusion: 3.95 ± 0.3 g, P = .87). Troponin levels significantly increased in the no aortic occlusion group but did not in the zone 1 aortic occlusion group. CONCLUSION Zone 1 aortic occlusion using resuscitative endovascular balloon occlusion of the aorta in a large animal dismounted complex blast injury model improved proximal mean arterial pressure while not significantly increasing intracranial pressure during balloon inflation. Observation up to 240 minutes postresuscitation did not show clinical signs of worsening brain injury or cardiac injury. These data suggest that in a dismounted complex blast injury swine model, resuscitative endovascular balloon occlusion of the aorta in zone 1 may provide neuro- and cardioprotection in the setting of blast traumatic brain injury. However, longer monitoring periods may be needed to confirm that the neuroprotection is lasting.
Collapse
Affiliation(s)
| | - Ernest E Moore
- Department of Surgery, University of Colorado, Aurora, CO; Ernest E. Moore Shock Trauma Center at Denver Health, CO
| | - Charles J Fox
- Department of Vascular Surgery, University of Maryland Vascular Surgery Baltimore, MD
| | - Daniel Kissau
- Department of Surgery, University of Colorado, Aurora, CO
| | - Margot DeBot
- Department of Surgery, University of Colorado, Aurora, CO
| | - Terry R Schaid
- Department of Surgery, University of Colorado, Aurora, CO
| | | | - Patrick Hom
- Department of Surgery, University of Colorado, Aurora, CO
| | - Miguel Fragoso
- Department of Surgery, University of Colorado, Aurora, CO
| | | | - Christopher Erickson
- Department of Vascular Surgery, University of Maryland Vascular Surgery Baltimore, MD
| | - Angelo D'Alessandro
- Department of Proteomics and Metabolomics, University of Colorado, Aurora, CO
| | - Kirk C Hansen
- Department of Vascular Surgery, University of Maryland Vascular Surgery Baltimore, MD; Department of Proteomics and Metabolomics, University of Colorado, Aurora, CO
| | | | - Christopher C Silliman
- Department of Pediatrics, University of Colorado, Aurora, CO; Vitalant Research Institute, Denver, CO
| | - Angela Sauaia
- Department of Health Systems, Management and Policy, School of Public Health, University of Colorado Denver, Aurora, CO
| |
Collapse
|
6
|
Zhang L, Jackson WJ, Bentil SA. Deformation of an airfoil-shaped brain surrogate under shock wave loading. J Mech Behav Biomed Mater 2021; 120:104513. [PMID: 34010798 DOI: 10.1016/j.jmbbm.2021.104513] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 03/30/2021] [Accepted: 04/07/2021] [Indexed: 10/21/2022]
Abstract
Improvised explosive devices (IEDs), during military operations, has increased the incidence of blast-induced traumatic brain injuries (bTBI). The shock wave is created following detonation of the IED. This shock wave propagates through the atmosphere and may cause bTBI. As a result, bTBI research has gained increased attention since this injury's mechanism is not thoroughly understood. To develop better protection and treatment against bTBI, further studies of soft material (e.g. brain and brain surrogate) deformation due to shock wave exposure are essential. However, the dynamic mechanical behavior of soft materials, subjected to high strain rates from shock wave exposure, remains unknown. Thus, an experimental approach was applied to study the interaction between the shock wave and an unconfined brain surrogate fabricated from a biomaterial (i.e. polydimethylsiloxane (PDMS)). The 1:70 ratio of curing agent-to-base determined the stiffness of the PDMS (Sylgard 184, Dow Corning Corporation). A stretched NACA 2414 (upper airfoil surface) geometry was utilized to resemble the shape of a porcine brain. Digital image correlation (DIC) technique was applied to measure the deformation on the brain surrogate's surface following shock wave exposure. A shock tube was utilized to create the shock wave and pressure transducers measured the pressure in the vicinity of the brain surrogate. A transient structural analysis using ANSYS Workbench was performed to predict the elastic modulus of 1:70 airfoil-shaped PDMS, at a strain rate on the order of 6 × 103 s-1. Both compression and protrusion of the PDMS surface were found due to the shock wave exposure. Negative pressure was found in a semi-ring area, which was the cause of protrusion. Oscillation of the brain surrogate, due to the shock wave loading, was found. The frequency of oscillation does not depend on the geometry. This work will add to the limited data describing the dynamic behavior of soft materials due to shock wave loading.
Collapse
Affiliation(s)
- Ling Zhang
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - William J Jackson
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - Sarah A Bentil
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA.
| |
Collapse
|
7
|
Belding JN, Englert RM, Fitzmaurice S, Jackson JR, Koenig HG, Hunter MA, Thomsen CJ, da Silva UO. Potential Health and Performance Effects of High-Level and Low-Level Blast: A Scoping Review of Two Decades of Research. Front Neurol 2021; 12:628782. [PMID: 33776888 PMCID: PMC7987950 DOI: 10.3389/fneur.2021.628782] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 02/10/2021] [Indexed: 01/06/2023] Open
Abstract
Although blast exposure has been recognized as a significant source of morbidity and mortality in military populations, our understanding of the effects of blast exposure, particularly low-level blast (LLB) exposure, on health outcomes remains limited. This scoping review provides a comprehensive, accessible review of the peer-reviewed literature that has been published on blast exposure over the past two decades, with specific emphasis on LLB. We conducted a comprehensive scoping review of the scientific literature published between January 2000 and 2019 pertaining to the effects of blast injury and/or exposure on human and animal health. A three-level review process with specific inclusion and exclusion criteria was used. A full-text review of all articles pertaining to LLB exposure was conducted and relevant study characteristics were extracted. The research team identified 3,215 blast-relevant articles, approximately half of which (55.4%) studied live humans, 16% studied animals, and the remainder were non-subjects research (e.g., literature reviews). Nearly all (99.49%) of the included studies were conducted by experts in medicine or epidemiology; approximately half of these articles were categorized into more than one medical specialty. Among the 51 articles identified as pertaining to LLB specifically, 45.1% were conducted on animals and 39.2% focused on human subjects. Animal studies of LLB predominately used shock tubes to induce various blast exposures in rats, assessed a variety of outcomes, and clearly demonstrated that LLB exposure is associated with brain injury. In contrast, the majority of LLB studies on humans were conducted among military and law enforcement personnel in training environments and had remarkable variability in the exposures and outcomes assessed. While findings suggest that there is the potential for LLB to harm human populations, findings are mixed and more research is needed. Although it is clear that more research is needed on this rapidly growing topic, this review highlights the detrimental effects of LLB on the health of both animals and humans. Future research would benefit from multidisciplinary collaboration, larger sample sizes, and standardization of terminology, exposures, and outcomes.
Collapse
Affiliation(s)
- Jennifer N. Belding
- Defense Health Group, Leidos, San Diego, CA, United States
- Health and Behavioral Sciences Department, Naval Health Research Center, San Diego, CA, United States
| | - Robyn M. Englert
- Defense Health Group, Leidos, San Diego, CA, United States
- Health and Behavioral Sciences Department, Naval Health Research Center, San Diego, CA, United States
| | - Shannon Fitzmaurice
- Defense Health Group, Leidos, San Diego, CA, United States
- Health and Behavioral Sciences Department, Naval Health Research Center, San Diego, CA, United States
| | - Jourdan R. Jackson
- Defense Health Group, Leidos, San Diego, CA, United States
- Health and Behavioral Sciences Department, Naval Health Research Center, San Diego, CA, United States
| | - Hannah G. Koenig
- Defense Health Group, Leidos, San Diego, CA, United States
- Health and Behavioral Sciences Department, Naval Health Research Center, San Diego, CA, United States
| | - Michael A. Hunter
- Defense Health Group, Leidos, San Diego, CA, United States
- Health and Behavioral Sciences Department, Naval Health Research Center, San Diego, CA, United States
| | - Cynthia J. Thomsen
- Health and Behavioral Sciences Department, Naval Health Research Center, San Diego, CA, United States
| | - Uade Olaghere da Silva
- Health and Behavioral Sciences Department, Naval Health Research Center, San Diego, CA, United States
| |
Collapse
|
8
|
Liang KJ, Carlson ES. Resistance, vulnerability and resilience: A review of the cognitive cerebellum in aging and neurodegenerative diseases. Neurobiol Learn Mem 2020; 170:106981. [PMID: 30630042 PMCID: PMC6612482 DOI: 10.1016/j.nlm.2019.01.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 12/14/2018] [Accepted: 01/03/2019] [Indexed: 12/12/2022]
Abstract
In the context of neurodegeneration and aging, the cerebellum is an enigma. Genetic markers of cellular aging in cerebellum accumulate more slowly than in the rest of the brain, and it generates unknown factors that may slow or even reverse neurodegenerative pathology in animal models of Alzheimer's Disease (AD). Cerebellum shows increased activity in early AD and Parkinson's disease (PD), suggesting a compensatory function that may mitigate early symptoms of neurodegenerative pathophysiology. Perhaps most notably, different parts of the brain accumulate neuropathological markers of AD in a recognized progression and generally, cerebellum is the last brain region to do so. Taken together, these data suggest that cerebellum may be resistant to certain neurodegenerative mechanisms. On the other hand, in some contexts of accelerated neurodegeneration, such as that seen in chronic traumatic encephalopathy (CTE) following repeated traumatic brain injury (TBI), the cerebellum appears to be one of the most susceptible brain regions to injury and one of the first to exhibit signs of pathology. Cerebellar pathology in neurodegenerative disorders is strongly associated with cognitive dysfunction. In neurodegenerative or neurological disorders associated with cerebellar pathology, such as spinocerebellar ataxia, cerebellar cortical atrophy, and essential tremor, rates of cognitive dysfunction, dementia and neuropsychiatric symptoms increase. When the cerebellum shows AD pathology, such as in familial AD, it is associated with earlier onset and greater severity of disease. These data suggest that when neurodegenerative processes are active in the cerebellum, it may contribute to pathological behavioral outcomes. The cerebellum is well known for comparing internal representations of information with observed outcomes and providing real-time feedback to cortical regions, a critical function that is disturbed in neuropsychiatric disorders such as intellectual disability, schizophrenia, dementia, and autism, and required for cognitive domains such as working memory. While cerebellum has reciprocal connections with non-motor brain regions and likely plays a role in complex, goal-directed behaviors, it has proven difficult to establish what it does mechanistically to modulate these behaviors. Due to this lack of understanding, it's not surprising to see the cerebellum reflexively dismissed or even ignored in basic and translational neuropsychiatric literature. The overarching goals of this review are to answer the following questions from primary literature: When the cerebellum is affected by pathology, is it associated with decreased cognitive function? When it is intact, does it play a compensatory or protective role in maintaining cognitive function? Are there theoretical frameworks for understanding the role of cerebellum in cognition, and perhaps, illnesses characterized by cognitive dysfunction? Understanding the role of the cognitive cerebellum in neurodegenerative diseases has the potential to offer insight into origins of cognitive deficits in other neuropsychiatric disorders, which are often underappreciated, poorly understood, and not often treated.
Collapse
Affiliation(s)
- Katharine J Liang
- University of Washington School of Medicine, Department of Psychiatry and Behavioral Sciences, Seattle, WA, United States
| | - Erik S Carlson
- University of Washington School of Medicine, Seattle, WA, United States.
| |
Collapse
|
9
|
Azar A, Bhagavathula KB, Hogan J, Ouellet S, Satapathy S, Dennison CR. Protective Headgear Attenuates Forces on the Inner Table and Pressure in the Brain Parenchyma During Blast and Impact: An Experimental Study Using a Simulant-Based Surrogate Model of the Human Head. J Biomech Eng 2020; 142:041009. [PMID: 31539422 DOI: 10.1115/1.4044926] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Indexed: 07/25/2024]
Abstract
Military personnel sustain head and brain injuries as a result of ballistic, blast, and blunt impact threats. Combat helmets are meant to protect the heads of these personnel during injury events. Studies show peak kinematics and kinetics are attenuated using protective headgear during impacts; however, there is limited experimental biomechanical literature that examines whether or not helmets mitigate peak mechanics delivered to the head and brain during blast. While the mechanical links between blast and brain injury are not universally agreed upon, one hypothesis is that blast energy can be transmitted through the head and into the brain. These transmissions can lead to rapid skull flexure and elevated pressures in the cranial vault, and, therefore, may be relevant in determining injury likelihood. Therefore, it could be argued that assessing a helmet for the ability to mitigate mechanics may be an appropriate paradigm for assessing the potential protective benefits of helmets against blast. In this work, we use a surrogate model of the head and brain to assess whether or not helmets and eye protection can alter mechanical measures during both head-level face-on blast and high forehead blunt impact events. Measurements near the forehead suggest head protection can attenuate brain parenchyma pressures by as much as 49% during blast and 52% during impact, and forces on the inner table of the skull by as much as 80% during blast and 84% during impact, relative to an unprotected head.
Collapse
Affiliation(s)
- Austin Azar
- Biomedical Instrumentation Lab, Department of Mechanical Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | | | - James Hogan
- Department of Mechanical Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Simon Ouellet
- Weapons Effects and Protection Section, Defence R&D Valcartier Research Center, Quebec, QC G3J 1X5, Canada
| | - Sikhanda Satapathy
- Chief(A) with Impact Physics Branch, U.S. Army Research Labs, Aberdeen Proving Ground, Aberdeen, MD 21005-5066
| | - Christopher R Dennison
- Biomedical Instrumentation Lab, Department of Mechanical Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| |
Collapse
|
10
|
Yu Y, Huang J, Tang X, Allison J, Sandlin D, Ding D, Pang Y, Zhang C, Chen T, Yin N, Chen L, Mustain W, Zhou W, Zhu H. Exposure to blast shock waves via the ear canal induces deficits in vestibular afferent function in rats. J Otol 2020; 15:77-85. [PMID: 32884557 PMCID: PMC7451608 DOI: 10.1016/j.joto.2020.01.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 01/09/2020] [Accepted: 01/15/2020] [Indexed: 12/11/2022] Open
Abstract
The ears are air-filled structures that are directly impacted during blast exposure. In addition to hearing loss and tinnitus, blast victims often complain of vertigo, dizziness and unsteady posture, suggesting that blast exposure induces damage to the vestibular end organs in the inner ear. However, the underlying mechanisms remain to be elucidated. In this report, single vestibular afferent activity and the vestibulo-ocular reflex (VOR) were investigated before and after exposure to blast shock waves (∼20 PSI) delivered into the left external ear canals of anesthetized rats. Single vestibular afferent activity was recorded from the superior branch of the left vestibular nerves of the blast-treated and control rats one day after blast exposure. Blast exposure reduced the spontaneous discharge rates of the otolith and canal afferents. Blast exposure also reduced the sensitivity of irregular canal afferents to sinusoidal head rotation at 0.5-2Hz. Blast exposure, however, resulted in few changes in the VOR responses to sinusoidal head rotation and translation. To the best of our knowledge, this is the first study that reports blast exposure-induced damage to vestibular afferents in an animal model. These results provide insights that may be helpful in developing biomarkers for early diagnosis of blast-induced vestibular deficits in military and civilian populations.
Collapse
Affiliation(s)
- Yue Yu
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Jun Huang
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Xuehui Tang
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Jerome Allison
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - David Sandlin
- Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, USA
| | - Dalian Ding
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, USA
| | - Yi Pang
- Department of Pediatric, University of Mississippi Medical Center, Jackson, MS, USA
| | - Chunming Zhang
- Department of Otolaryngology, First Affiliated Hospital, Shanxi Medical University, Taiyuan Shanxi, 030001, China
| | - Tianwen Chen
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Nathan Yin
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Lan Chen
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - William Mustain
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Wu Zhou
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Neurology, University of Mississippi Medical Center, Jackson, MS, USA
| | - Hong Zhu
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| |
Collapse
|
11
|
McCarty AK, Zhang L, Hansen S, Jackson WJ, Bentil SA. Viscoelastic properties of shock wave exposed brain tissue subjected to unconfined compression experiments. J Mech Behav Biomed Mater 2019; 100:103380. [PMID: 31446342 DOI: 10.1016/j.jmbbm.2019.103380] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 07/26/2019] [Accepted: 07/27/2019] [Indexed: 12/15/2022]
Abstract
Traumatic brain injuries (TBI) affect millions of people each year. While research has been dedicated to determining the mechanical properties of the uninjured brain, there has been a lack of investigation on the mechanical properties of the brain after experiencing a primary blast-induced TBI. In this paper, whole porcine brains were exposed to a shock wave to simulate blast-induced TBI. First, ten (10) brains were subjected to unconfined compression experiments immediately following shock wave exposure. In addition, 22 brains exposed to a shock wave were placed in saline solution and refrigerated between 30 minutes and 6.0 hours before undergoing unconfined compression experiments. This study aimed to investigate the effect of a time delay on the viscoelastic properties in the event that an experiment cannot be completed immediately. Samples from both soaked and freshly extracted brains were subjected to compressive rates of 5, 50, and 500 mm/min during the unconfined compression experiments. The fractional Zener (FZ) viscoelastic model was applied to obtain the brain's material properties. The length of time in the solution statistically influenced three of the four FZ coefficients, E0 (instantaneous elastic response), τ0 (relaxation time), and α (fractional order). Further, the compressive rate statistically influenced τ0 and α.
Collapse
Affiliation(s)
- Annastacia K McCarty
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - Ling Zhang
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - Sarah Hansen
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - William J Jackson
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - Sarah A Bentil
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA.
| |
Collapse
|
12
|
Haran FJ, Handy JD, Servatius RJ, Rhea CK, Tsao JW. Acute neurocognitive deficits in active duty service members following subconcussive blast exposure. APPLIED NEUROPSYCHOLOGY-ADULT 2019; 28:297-309. [PMID: 31269805 DOI: 10.1080/23279095.2019.1630627] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Military service members are frequently subjected to subconcussive blast events during training and deployment. Emerging evidence suggests blast exposures of these magnitudes may have long-term consequences for dimensions of cognitive function. Less is known about cognitive sequelae acutely following deployment-related subconcussive blast events. The current study addressed this knowledge gap by assessing the extent to which subconcussive blast exposure affected performance on the Automated Neuropsychological Assessment Metrics 4 TBI-MIL (ANAM). Baseline-referenced and normative comparisons of archival ANAM data were analyzed for a cohort of personnel who were exposed to blast (blast group; n = 27) and personnel who were not exposed to blast (no-blast group; n = 36) that were otherwise asymptomatic for a concussion. The blast group exhibited statistically significant lower scores compared to the no-blast group (between-subjects), baseline assessments (within-subjects), and an age-matched normative population. Normative comparisons revealed that the scores for the reaction time subtests (i.e., procedural and both simple reaction time tasks) were outside the range of normal functioning (1 SD) and reliable change indices revealed clinically meaningful change only for simple reaction time. The results highlight covert effects of subconcussive blast exposure that may warrant further monitoring in the immediate aftermath of a blast event.
Collapse
Affiliation(s)
- F J Haran
- Neurotrauma Department, Naval Medical Research Center, Silver Spring, Maryland, USA.,Department of Psychiatry, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.,Department of Kinesiology, University of North Carolina at Greensboro, Greensboro, North Carolina, USA
| | - Justin D Handy
- Stress and Motivated Behavior Institute, Syracuse, New York, USA
| | - Richard J Servatius
- Stress and Motivated Behavior Institute, Syracuse, New York, USA.,Research & Development, Syracuse VA Medical Center, Syracuse, New York, USA.,Department of Psychiatry, State University of New York Upstate Medical University, Syracuse, New York, USA
| | - Christopher K Rhea
- Department of Kinesiology, University of North Carolina at Greensboro, Greensboro, North Carolina, USA
| | - Jack W Tsao
- Department of Neurology, University of Tennessee Health Science Center, Memphis, Tennessee, USA.,Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, Tennessee, USA.,Department of Neurology, Memphis Veterans Affairs Medical Center, Memphis, Tennessee, USA
| |
Collapse
|
13
|
McCarty AK, Zhang L, Hansen S, Jackson WJ, Bentil SA. Influence of saline solution absorption and compressive rate on the material properties of brain tissue. J Mech Behav Biomed Mater 2019; 97:355-364. [PMID: 31154155 DOI: 10.1016/j.jmbbm.2019.05.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/18/2019] [Accepted: 05/17/2019] [Indexed: 01/22/2023]
Abstract
Traumatic brain injuries (TBI) affect millions of people each year and can result in long-term difficulties in thinking or focusing. Due to the number of people affected by these injuries, significant research has been dedicated to determining the mechanical properties of the brain using postmortem tissue from animals harvested within 24 h. The postmortem brain tissue is often stored in a solution until a rheological experiment is ready to begin. However, the effect of storage duration on the mechanical behavior of brain tissue is not understood. In this paper, postmortem porcine brains were placed in normal saline solution (0.9% NaCl) and refrigerated between 30 min and 6.5 h to allow the brain to absorb the solution. Afterwards, samples from both soaked and freshly extracted brains were subjected to unconfined compression tests at compressive rates of 5, 50, and 500 mm/min. The fractional Zener viscoelastic model was applied to obtain the brain's mechanical properties. While the results did not show a significant relationship between absorption and the long-term stiffness (E∞), both the relaxation time (τ0) and fractional order (α) were statistically influenced by both the length of time in the solution and compressive rate. Further, the instantaneous stiffness (E0) was statistically influenced by the length of time in solution, though not the compressive rate.
Collapse
Affiliation(s)
- Annastacia K McCarty
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - Ling Zhang
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - Sarah Hansen
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - William J Jackson
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - Sarah A Bentil
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA.
| |
Collapse
|
14
|
Zhang L, Jackson WJ, Bentil SA. The mechanical behavior of brain surrogates manufactured from silicone elastomers. J Mech Behav Biomed Mater 2019; 95:180-190. [PMID: 31009902 DOI: 10.1016/j.jmbbm.2019.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/03/2019] [Accepted: 04/05/2019] [Indexed: 01/05/2023]
Abstract
The ongoing conflict against terrorism has resulted in an escalation of blast-induced traumatic brain injuries (bTBI) caused by improvised explosive devices (IEDs). The destructive IEDs create a blast wave that travels through the atmosphere. Blast-induced traumatic brain injuries, attributed to the blast wave, can cause life-threatening injuries and fatalities. This study aims to find a surrogate brain material for assessing the effectiveness of head protection systems designed to mitigate bTBI. Polydimethylsiloxane (PDMS) is considered as the surrogate brain material. The stiffness of PDMS (Sylgard 184, Dow Corning Corp.) can be controlled by varying the ratio of base and curing agent. Cylindrical PDMS specimen with ratios of 1:10, 1:70, and 1:80 were subjected to unconfined compression experiments at linear rates of 5 mm/min, 50 mm/min, and 500 mm/min. A ramp-hold strain profile was used to simulate a stress relaxation experiment. The fractional Zener viscoelastic model was used to describe the stress relaxation response, after optimization of the material constants for the brain surrogate and shock wave exposure brain tissue. The results show that the low cost PDMS can be used as a surrogate brain material to study the dynamic brain response to blast wave exposure.
Collapse
Affiliation(s)
- Ling Zhang
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - William J Jackson
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - Sarah A Bentil
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA.
| |
Collapse
|
15
|
Gama Sosa MA, De Gasperi R, Perez Garcia GS, Perez GM, Searcy C, Vargas D, Spencer A, Janssen PL, Tschiffely AE, McCarron RM, Ache B, Manoharan R, Janssen WG, Tappan SJ, Hanson RW, Gandy S, Hof PR, Ahlers ST, Elder GA. Low-level blast exposure disrupts gliovascular and neurovascular connections and induces a chronic vascular pathology in rat brain. Acta Neuropathol Commun 2019; 7:6. [PMID: 30626447 PMCID: PMC6327415 DOI: 10.1186/s40478-018-0647-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 12/06/2018] [Indexed: 01/15/2023] Open
Abstract
Much concern exists over the role of blast-induced traumatic brain injury (TBI) in the chronic cognitive and mental health problems that develop in veterans and active duty military personnel. The brain vasculature is particularly sensitive to blast injury. The aim of this study was to characterize the evolving molecular and histologic alterations in the neurovascular unit induced by three repetitive low-energy blast exposures (3 × 74.5 kPa) in a rat model mimicking human mild TBI or subclinical blast exposure. High-resolution two-dimensional differential gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry of purified brain vascular fractions from blast-exposed animals 6 weeks post-exposure showed decreased levels of vascular-associated glial fibrillary acidic protein (GFAP) and several neuronal intermediate filament proteins (α-internexin and the low, middle, and high molecular weight neurofilament subunits). Loss of these proteins suggested that blast exposure disrupts gliovascular and neurovascular interactions. Electron microscopy confirmed blast-induced effects on perivascular astrocytes including swelling and degeneration of astrocytic endfeet in the brain cortical vasculature. Because the astrocyte is a major sensor of neuronal activity and regulator of cerebral blood flow, structural disruption of gliovascular integrity within the neurovascular unit should impair cerebral autoregulation. Disrupted neurovascular connections to pial and parenchymal blood vessels might also affect brain circulation. Blast exposures also induced structural and functional alterations in the arterial smooth muscle layer. Interestingly, by 8 months after blast exposure, GFAP and neuronal intermediate filament expression had recovered to control levels in isolated brain vascular fractions. However, despite this recovery, a widespread vascular pathology was still apparent at 10 months after blast exposure histologically and on micro-computed tomography scanning. Thus, low-level blast exposure disrupts gliovascular and neurovascular connections while inducing a chronic vascular pathology.
Collapse
|
16
|
Dougherty AL, MacGregor AJ, Viirre E, Clouser MC, Han PP, Quinn KH, Galarneau MR. Preliminary study of hearing protection and non-impact, blast-induced concussion in US military personnel. Brain Inj 2018; 32:1423-1428. [DOI: 10.1080/02699052.2018.1496476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Amber L. Dougherty
- Medical Modeling, Simulation, and Mission Support Department, Naval Health Research Center, San Diego, CA, USA
| | - Andrew J. MacGregor
- Medical Modeling, Simulation, and Mission Support Department, Naval Health Research Center, San Diego, CA, USA
| | - Erik Viirre
- Department of Cognitive Science, University of California San Diego, San Diego, CA, USA
| | - Mary C. Clouser
- Medical Modeling, Simulation, and Mission Support Department, Naval Health Research Center, San Diego, CA, USA
| | - Peggy P. Han
- Medical Modeling, Simulation, and Mission Support Department, Naval Health Research Center, San Diego, CA, USA
| | - Kimberly H. Quinn
- Medical Modeling, Simulation, and Mission Support Department, Naval Health Research Center, San Diego, CA, USA
| | - Michael R. Galarneau
- Medical Modeling, Simulation, and Mission Support Department, Naval Health Research Center, San Diego, CA, USA
| |
Collapse
|
17
|
Haider MN, Leddy JJ, Hinds AL, Aronoff N, Rein D, Poulsen D, Willer BS. Intracranial pressure changes after mild traumatic brain injury: a systematic review. Brain Inj 2018; 32:809-815. [PMID: 29701515 PMCID: PMC6192525 DOI: 10.1080/02699052.2018.1469045] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 02/12/2018] [Accepted: 04/21/2018] [Indexed: 10/17/2022]
Abstract
OBJECTIVE Intracranial pressure (ICP) after mild traumatic brain injury (mTBI) is poorly studied due to lack of sensitive non-invasive methods. The purpose of this review was to summarize the existing knowledge of changes in ICP after mTBI. Literature selection: PubMed, Embase, CINAHL, and Scopus were searched by three reviewers independently up to December 2016. INCLUSION CRITERIA animal and human studies measuring ICP and brain oedema after an mTBI. EXCLUSION CRITERIA moderate and severe forms of traumatic brain injury, repeat samples, and studies that measured ICP at the time of impact but not after. Study quality was assessed using Downs and Black criteria. RESULTS Of 1067 papers, 9 studies were included. In human studies, one provided direct evidence on increased, one provided indirect evidence of increased, and two provided indirect evidence of decreased ICP. In animal studies, three studies provided direct evidence of increased, one provided indirect evidence of increased, and one provided indirect evidence of no change in ICP. CONCLUSION The existing research suggests that there may be increased ICP after mTBI and animal studies suggest an elevation for days which returns to baseline, which corresponds with functional and symptomatic recovery. Future human studies using sensitive indirect methods to measure ICP longitudinally after mTBI are needed.
Collapse
Affiliation(s)
- Mohammad N Haider
- Department of Orthopedics and Sports Medicine, State University of New York at Buffalo
- Department of Neuroscience, State University of New York at Buffalo
| | - John J Leddy
- Department of Orthopedics and Sports Medicine, State University of New York at Buffalo
| | - Andrea L Hinds
- Department of Orthopedics and Sports Medicine, State University of New York at Buffalo
| | - Nell Aronoff
- Health Sciences Library, State University of New York at Buffalo
| | - Diane Rein
- Health Sciences Library, State University of New York at Buffalo
| | - David Poulsen
- Department of Neurosurgery, State University of New York at Buffalo
| | - Barry S Willer
- Department of Psychiatry, State University of New York at Buffalo
| |
Collapse
|
18
|
Sorby-Adams AJ, Vink R, Turner RJ. Large animal models of stroke and traumatic brain injury as translational tools. Am J Physiol Regul Integr Comp Physiol 2018. [PMID: 29537289 DOI: 10.1152/ajpregu.00163.2017] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Acute central nervous system injury, encompassing traumatic brain injury (TBI) and stroke, accounts for a significant burden of morbidity and mortality worldwide. Studies in animal models have greatly enhanced our understanding of the complex pathophysiology that underlies TBI and stroke and enabled the preclinical screening of over 1,000 novel therapeutic agents. Despite this, the translation of novel therapeutics from experimental models to clinical therapies has been extremely poor. One potential explanation for this poor clinical translation is the choice of experimental model, given that the majority of preclinical TBI and ischemic stroke studies have been conducted in small animals, such as rodents, which have small lissencephalic brains. However, the use of large animal species such as nonhuman primates, sheep, and pigs, which have large gyrencephalic human-like brains, may provide an avenue to improve clinical translation due to similarities in neuroanatomical structure when compared with widely adopted rodent models. This purpose of this review is to provide an overview of large animal models of TBI and ischemic stroke, including the surgical considerations, key benefits, and limitations of each approach.
Collapse
Affiliation(s)
- Annabel J Sorby-Adams
- Adelaide Medical School and Adelaide Centre for Neuroscience Research, The University of Adelaide , Adelaide, South Australia
| | - Robert Vink
- Sansom Institute for Health Research, University of South Australia , Adelaide, South Australia
| | - Renée J Turner
- Adelaide Medical School and Adelaide Centre for Neuroscience Research, The University of Adelaide , Adelaide, South Australia
| |
Collapse
|
19
|
Song H, Cui J, Simonyi A, Johnson CE, Hubler GK, DePalma RG, Gu Z. Linking blast physics to biological outcomes in mild traumatic brain injury: Narrative review and preliminary report of an open-field blast model. Behav Brain Res 2018; 340:147-158. [DOI: 10.1016/j.bbr.2016.08.037] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 08/13/2016] [Accepted: 08/19/2016] [Indexed: 12/14/2022]
|
20
|
Skotak M, Alay E, Chandra N. On the Accurate Determination of Shock Wave Time-Pressure Profile in the Experimental Models of Blast-Induced Neurotrauma. Front Neurol 2018; 9:52. [PMID: 29467718 PMCID: PMC5808170 DOI: 10.3389/fneur.2018.00052] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 01/19/2018] [Indexed: 01/04/2023] Open
Abstract
Measurement issues leading to the acquisition of artifact-free shock wave pressure-time profiles are discussed. We address the importance of in-house sensor calibration and data acquisition sampling rate. Sensor calibration takes into account possible differences between calibration methodology in a manufacturing facility, and those used in the specific laboratory. We found in-house calibration factors of brand new sensors differ by less than 10% from their manufacturer supplied data. Larger differences were noticeable for sensors that have been used for hundreds of experiments and were as high as 30% for sensors close to the end of their useful lifetime. These observations were despite the fact that typical overpressures in our experiments do not exceed 50 psi for sensors that are rated at 1,000 psi maximum pressure. We demonstrate that sampling rate of 1,000 kHz is necessary to capture the correct rise time values, but there were no statistically significant differences between peak overpressure and impulse values for low-intensity shock waves (Mach number <2) at lower rates. We discuss two sources of experimental errors originating from mechanical vibration and electromagnetic interference on the quality of a waveform recorded using state-of-the-art high-frequency pressure sensors. The implementation of preventive measures, pressure acquisition artifacts, and data interpretation with examples, are provided in this paper that will help the community at large to avoid these mistakes. In order to facilitate inter-laboratory data comparison, common reporting standards should be developed by the blast TBI research community. We noticed the majority of published literature on the subject limits reporting to peak overpressure; with much less attention directed toward other important parameters, i.e., duration, impulse, and dynamic pressure. These parameters should be included as a mandatory requirement in publications so the results can be properly compared with others.
Collapse
Affiliation(s)
- Maciej Skotak
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, United States
| | - Eren Alay
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, United States
| | - Namas Chandra
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, United States
| |
Collapse
|
21
|
Yamamoto S, DeWitt DS, Prough DS. Impact & Blast Traumatic Brain Injury: Implications for Therapy. Molecules 2018; 23:E245. [PMID: 29373501 PMCID: PMC6017013 DOI: 10.3390/molecules23020245] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 01/22/2018] [Accepted: 01/24/2018] [Indexed: 12/23/2022] Open
Abstract
Traumatic brain injury (TBI) is one of the most frequent causes of combat casualties in Operations Iraqi Freedom (OIF), Enduring Freedom (OEF), and New Dawn (OND). Although less common than combat-related blast exposure, there have been significant numbers of blast injuries in civilian populations in the United States. Current United States Department of Defense (DoD) ICD-9 derived diagnoses of TBI in the DoD Health Care System show that, for 2016, severe and moderate TBIs accounted for just 0.7% and 12.9%, respectively, of the total of 13,634 brain injuries, while mild TBIs (mTBIs) accounted for 86% of the total. Although there is a report that there are differences in the frequency of long-term complications in mTBI between blast and non-blast TBIs, clinical presentation is classified by severity score rather than mechanism because severity scoring is associated with prognosis in clinical practice. Blast TBI (bTBI) is unique in its pathology and mechanism, but there is no treatment specific for bTBIs-these patients are treated similarly to TBIs in general and therapy is tailored on an individual basis. Currently there is no neuroprotective drug recommended by the clinical guidelines based on evidence.
Collapse
Affiliation(s)
- Satoshi Yamamoto
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Douglas S DeWitt
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Donald S Prough
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX 77555, USA.
| |
Collapse
|
22
|
Fievisohn E, Bailey Z, Guettler A, VandeVord P. Primary Blast Brain Injury Mechanisms: Current Knowledge, Limitations, and Future Directions. J Biomech Eng 2018; 140:2666247. [DOI: 10.1115/1.4038710] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Indexed: 12/18/2022]
Abstract
Mild blast traumatic brain injury (bTBI) accounts for the majority of brain injury in United States service members and other military personnel worldwide. The mechanisms of primary blast brain injury continue to be disputed with little evidence to support one or a combination of theories. The main hypotheses addressed in this review are blast wave transmission through the skull orifices, direct cranial transmission, skull flexure dynamics, thoracic surge, acceleration, and cavitation. Each possible mechanism is discussed using available literature with the goal of focusing research efforts to address the limitations and challenges that exist in blast injury research. Multiple mechanisms may contribute to the pathology of bTBI and could be dependent on magnitudes and orientation to blast exposure. Further focused biomechanical investigation with cadaver, in vivo, and finite element models would advance our knowledge of bTBI mechanisms. In addition, this understanding could guide future research and contribute to the greater goal of developing relevant injury criteria and mandates to protect our soldiers on the battlefield.
Collapse
Affiliation(s)
- Elizabeth Fievisohn
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 440 Kelly Hall, 325 Stanger Street, Blacksburg, VA 24061 e-mail:
| | - Zachary Bailey
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 440 Kelly Hall, 325 Stanger Street, Blacksburg, VA 24061 e-mail:
| | - Allison Guettler
- Department of Mechanical Engineering, Virginia Tech, 440 Kelly Hall, 325 Stanger Street, Blacksburg, VA 24061 e-mail:
| | - Pamela VandeVord
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 317 Kelly Hall, 325 Stanger Street, Blacksburg, VA 24061; Salem Veterans Affairs Medical Center, Salam, VA 24153 e-mail:
| |
Collapse
|
23
|
Cernak I. Understanding blast-induced neurotrauma: how far have we come? Concussion 2017; 2:CNC42. [PMID: 30202583 PMCID: PMC6093818 DOI: 10.2217/cnc-2017-0006] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 05/08/2017] [Indexed: 12/14/2022] Open
Abstract
Blast injuries, including blast-induced neurotrauma (BINT), are caused by blast waves generated during an explosion. Accordingly, their history coincides with that of explosives. Hence, it is intriguing that, after more than 1000 years of using explosives, our understanding of the pathological consequences of blast and body/brain interactions is extremely limited. Postconflict recovery mechanisms seemingly include the suppression of painful experiences, such as explosive injuries. Unfortunately, ignoring the knowledge generated by previous generations of scientists retards research progress, leading to superfluous and repetitive studies. This article summarizes clinical and experimental findings published about blast injuries and BINT following the wars of the 20th and 21th centuries. Moreover, it offers a personal view on potential factors interfering with the progress of BINT research working toward providing better diagnosis, treatment and rehabilitation for military personnel affected by blast exposure.
Collapse
Affiliation(s)
- Ibolja Cernak
- Faculty of Rehabilitation Medicine, University of Alberta, Corbett Hall 3–48, Edmonton Alberta, T6G 2G4, Canada
| |
Collapse
|
24
|
Vink R. Large animal models of traumatic brain injury. J Neurosci Res 2017; 96:527-535. [PMID: 28500771 DOI: 10.1002/jnr.24079] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 03/14/2017] [Accepted: 04/12/2017] [Indexed: 12/11/2022]
Abstract
Animal models are essential to gain a deeper understanding of the pathophysiology associated with traumatic brain injury (TBI). Rodent models of TBI have proven highly valuable with respect to the information they have provided over the years, particularly when it comes to the molecular understanding of injury mechanisms. However, there has been a failure to translate the successes in therapeutic treatment of TBI in rodents, which many believe may be related to their different brain anatomy compared with humans. Specifically, the rodent lissencephalic brain within its bony skull responds differently to injury than a human gyrencephalic brain, particularly from a biomechanical and physiological perspective. There is now far greater interest in developing more clinically relevant, large animal models of TBI so as to enhance the possibility of successful clinical translation. The current mini-review highlights the differences between lissencephalic and gyrencephalic brains, emphasizing how these differences might impact studies of TBI. Thereafter follows a summary of the different large animal models, with a critical analysis of their strengths and weaknesses.
Collapse
Affiliation(s)
- Robert Vink
- Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| |
Collapse
|
25
|
Kallakuri S, Desai A, Feng K, Tummala S, Saif T, Chen C, Zhang L, Cavanaugh JM, King AI. Neuronal Injury and Glial Changes Are Hallmarks of Open Field Blast Exposure in Swine Frontal Lobe. PLoS One 2017; 12:e0169239. [PMID: 28107370 PMCID: PMC5249202 DOI: 10.1371/journal.pone.0169239] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 12/13/2016] [Indexed: 02/03/2023] Open
Abstract
With the rapid increase in the number of blast induced traumatic brain injuries and associated neuropsychological consequences in veterans returning from the operations in Iraq and Afghanistan, the need to better understand the neuropathological sequelae following exposure to an open field blast exposure is still critical. Although a large body of experimental studies have attempted to address these pathological changes using shock tube models of blast injury, studies directed at understanding changes in a gyrencephalic brain exposed to a true open field blast are limited and thus forms the focus of this study. Anesthetized, male Yucatan swine were subjected to forward facing medium blast overpressure (peak side on overpressure 224-332 kPa; n = 7) or high blast overpressure (peak side on overpressure 350-403 kPa; n = 5) by detonating 3.6 kg of composition-4 charge. Sham animals (n = 5) were subjected to all the conditions without blast exposure. After a 3-day survival period, the brain was harvested and sections from the frontal lobes were processed for histological assessment of neuronal injury and glial reactivity changes. Significant neuronal injury in the form of beta amyloid precursor protein immunoreactive zones in the gray and white matter was observed in the frontal lobe sections from both the blast exposure groups. A significant increase in the number of astrocytes and microglia was also observed in the blast exposed sections compared to sham sections. We postulate that the observed acute injury changes may progress to chronic periods after blast and may contribute to short and long-term neuronal degeneration and glial mediated inflammation.
Collapse
Affiliation(s)
- Srinivasu Kallakuri
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, United States of America
| | - Alok Desai
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, United States of America
| | - Ke Feng
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, United States of America
| | - Sharvani Tummala
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, United States of America
| | - Tal Saif
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, United States of America
| | - Chaoyang Chen
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, United States of America
| | - Liying Zhang
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, United States of America
| | - John M. Cavanaugh
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, United States of America
| | - Albert I. King
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, United States of America
| |
Collapse
|
26
|
Feng K, Zhang L, Jin X, Chen C, Kallakuri S, Saif T, Cavanaugh J, King A. Biomechanical Responses of the Brain in Swine Subject to Free-Field Blasts. Front Neurol 2016; 7:179. [PMID: 27822197 PMCID: PMC5075707 DOI: 10.3389/fneur.2016.00179] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 10/04/2016] [Indexed: 01/05/2023] Open
Abstract
Blast-induced traumatic brain injury (bTBI) is a signature wound of modern warfare. The current incomplete understanding of its injury mechanism impedes the development of strategies for effective protection of bTBI. Despite a considerable amount of experimental animal studies focused on the evaluation of brain neurotrauma caused by blast exposure, there is very limited knowledge on the biomechanical responses of the gyrenecephalic brain subjected to primary free-field blast waves imposed in vivo. This study aims to evaluate the external and internal mechanical responses of the brain against different levels of blast loading with Yucatan swine in free field. The incident overpressure (IOP) was generated using 3.6 kg of C4 charge placed at three standoff distances from the swine. Five swine were exposed to a total of 19 blasts. The three average peak IOP pressure levels in this study were 148.8, 278.9, and 409.2 kPa as measured by a pencil probe. The duration of the first positive wave was in the range of 2.1–3 ms. Pressure changes in the brain and head kinematics were recorded with intracranial pressure (ICP) sensors, linear accelerometers, and angular rate sensors. The corresponding average peak ICPs were in the range of 79–143, 210–281, and 311–414 kPa designated as low, medium, and high blast level, respectively. Peak head linear accelerations were in the range of 120–412 g. A positive correlation between IOP and its corresponding biomechanical responses of the brain was also observed. These experimental data can be used to validate computer models of bTBI.
Collapse
Affiliation(s)
- Ke Feng
- Department of Biomedical Engineering, Wayne State University , Detroit, MI , USA
| | - Liying Zhang
- Department of Biomedical Engineering, Wayne State University , Detroit, MI , USA
| | - Xin Jin
- Department of Biomedical Engineering, Wayne State University , Detroit, MI , USA
| | - Chaoyang Chen
- Department of Biomedical Engineering, Wayne State University , Detroit, MI , USA
| | - Srinivasu Kallakuri
- Department of Biomedical Engineering, Wayne State University , Detroit, MI , USA
| | - Tal Saif
- Department of Biomedical Engineering, Wayne State University , Detroit, MI , USA
| | - John Cavanaugh
- Department of Biomedical Engineering, Wayne State University , Detroit, MI , USA
| | - Albert King
- Department of Biomedical Engineering, Wayne State University , Detroit, MI , USA
| |
Collapse
|
27
|
Intracranial venous injury, thrombosis and repair as hallmarks of mild blast traumatic brain injury in rats: Lessons from histological and immunohistochemical studies of decalcified sectioned heads and correlative microarray analysis. J Neurosci Methods 2016; 272:56-68. [DOI: 10.1016/j.jneumeth.2016.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 02/01/2016] [Accepted: 02/01/2016] [Indexed: 11/18/2022]
|
28
|
Kuriakose M, Skotak M, Misistia A, Kahali S, Sundaramurthy A, Chandra N. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen. PLoS One 2016; 11:e0161597. [PMID: 27603017 PMCID: PMC5014318 DOI: 10.1371/journal.pone.0161597] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 08/08/2016] [Indexed: 11/19/2022] Open
Abstract
The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent.
Collapse
Affiliation(s)
- Matthew Kuriakose
- Center for Injury Biomechanics, Materials and Medicine (CIBM), Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, 07102–1982, United States of America
| | - Maciej Skotak
- Center for Injury Biomechanics, Materials and Medicine (CIBM), Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, 07102–1982, United States of America
| | - Anthony Misistia
- Center for Injury Biomechanics, Materials and Medicine (CIBM), Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, 07102–1982, United States of America
| | - Sudeepto Kahali
- Center for Injury Biomechanics, Materials and Medicine (CIBM), Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, 07102–1982, United States of America
| | - Aravind Sundaramurthy
- Center for Injury Biomechanics, Materials and Medicine (CIBM), Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, 07102–1982, United States of America
| | - Namas Chandra
- Center for Injury Biomechanics, Materials and Medicine (CIBM), Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, 07102–1982, United States of America
- * E-mail:
| |
Collapse
|
29
|
Sawyer TW, Wang Y, Ritzel DV, Josey T, Villanueva M, Shei Y, Nelson P, Hennes G, Weiss T, Vair C, Fan C, Barnes J. High-Fidelity Simulation of Primary Blast: Direct Effects on the Head. J Neurotrauma 2016; 33:1181-93. [PMID: 26582146 DOI: 10.1089/neu.2015.3914] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The role of primary blast in blast-induced traumatic brain injury (bTBI) is controversial in part due to the technical difficulties of generating free-field blast conditions in the laboratory. The use of traditional shock tubes often results in artifacts, particularly of dynamic pressure, whereas the forces affecting the head are dependent on where the animal is placed relative to the tube, whether the exposure is whole-body or head-only, and on how the head is actually exposed to the insult (restrained or not). An advanced blast simulator (ABS) has been developed that enables high-fidelity simulation of free-field blastwaves, including sharply defined static and dynamic overpressure rise times, underpressures, and secondary shockwaves. Rats were exposed in head-only fashion to single-pulse blastwaves of 15 to 30 psi static overpressure. Head restraints were configured so as to eliminate concussive and minimize whiplash forces exerted on the head, as shown by kinematic analysis. No overt signs of trauma were present in the animals post-exposure. However, significant changes in brain 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) and neurofilament heavy chain levels were evident by 7 days. In contrast to most studies of primary blast-induced TBI (PbTBI), no elevation of glial fibrillary acidic protein (GFAP) levels was noted when head movement was minimized. The ABS described in this article enables the generation of shockwaves highly representative of free-field blast. The use of this technology, in concert with head-only exposure, minimized head movement, and the kinematic analysis of the forces exerted on the head provide convincing evidence that primary blast directly causes changes in brain function and that GFAP may not be an appropriate biomarker of PbTBI.
Collapse
Affiliation(s)
- Thomas W Sawyer
- 1 Defence Research & Development Canada , Medicine Hat, Alberta, Canada
| | - Yushan Wang
- 1 Defence Research & Development Canada , Medicine Hat, Alberta, Canada
| | | | - Tyson Josey
- 1 Defence Research & Development Canada , Medicine Hat, Alberta, Canada
| | - Mercy Villanueva
- 1 Defence Research & Development Canada , Medicine Hat, Alberta, Canada
| | - Yimin Shei
- 1 Defence Research & Development Canada , Medicine Hat, Alberta, Canada
| | - Peggy Nelson
- 1 Defence Research & Development Canada , Medicine Hat, Alberta, Canada
| | - Grant Hennes
- 1 Defence Research & Development Canada , Medicine Hat, Alberta, Canada
| | - Tracy Weiss
- 1 Defence Research & Development Canada , Medicine Hat, Alberta, Canada
| | - Cory Vair
- 1 Defence Research & Development Canada , Medicine Hat, Alberta, Canada
| | - Changyang Fan
- 3 Canada West Biosciences , Calgary, Alberta, Canada
| | - Julia Barnes
- 3 Canada West Biosciences , Calgary, Alberta, Canada
| |
Collapse
|
30
|
Adhikari U, Goliaei A, Berkowitz ML. Nanobubbles, cavitation, shock waves and traumatic brain injury. Phys Chem Chem Phys 2016; 18:32638-32652. [DOI: 10.1039/c6cp06704b] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Shock wave induced cavitation denaturates blood–brain barrier tight junction proteins; this may result in various neurological complications.
Collapse
Affiliation(s)
- Upendra Adhikari
- Department of Chemistry
- University of North Carolina at Chapel Hill
- Chapel Hill
- USA
| | - Ardeshir Goliaei
- Department of Biochemistry and Biophysics and Program in Molecular and Cellular Biophysics
- University of North Carolina at Chapel Hill
- Chapel Hill
- USA
| | - Max L. Berkowitz
- Department of Chemistry
- University of North Carolina at Chapel Hill
- Chapel Hill
- USA
| |
Collapse
|
31
|
Sliozberg Y, Chantawansri T. Damage in spherical cellular membrane generated by the shock waves: coarse-grained molecular dynamics simulation of lipid vesicle. J Chem Phys 2015; 141:184904. [PMID: 25399159 DOI: 10.1063/1.4901130] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Traumatic Brain Injury is a major health issue that is hard to diagnose since it often occurs without signs of external injuries. While it is well known that exposure of biological cells to shock waves causes damage to the cell membrane, it is currently unknown by which mechanisms damage is caused, and how it depends on physical parameters such as shock wave velocity, shock pulse duration, or shock pulse shape. In this computational study, we use a coarse-grained model of the lipid vesicle as a generic model of a cell membrane to elucidate the general principles of the cellular damage induced by the shock wave direct passage through the cranium. Results indicate that the extent of the liposome compression does not strongly depend on the pressure pulse and that liposome extension is very sensitive to the change in the negative pressure phase. The structural integrity of the vesicle is altered as pores form in the lipid membrane at overall pressure impulses generated by supersonic shock waves, which are greater than 5 Pa·s at single or repetitive exposure. Consequently, these permeability changes may lead to changes in the influx of sodium, potassium, and calcium ions.
Collapse
Affiliation(s)
- Yelena Sliozberg
- TKC Global at U.S. Army Research Laboratory, 4600 Deer Creek Loop, Aberdeen Proving Ground, Maryland 21005-5069, USA
| | - Tanya Chantawansri
- U.S. Army Research Laboratory, 4600 Deer Creek Loop, Aberdeen Proving Ground, Maryland 21005-5069, USA
| |
Collapse
|
32
|
Zhu F, Kalra A, Saif T, Yang Z, Yang KH, King AI. Parametric analysis of the biomechanical response of head subjected to the primary blast loading – a data mining approach. Comput Methods Biomech Biomed Engin 2015; 19:1053-9. [DOI: 10.1080/10255842.2015.1091887] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
33
|
Divani AA, Murphy AJ, Meints J, Sadeghi-Bazargani H, Nordberg J, Monga M, Low WC, Bhatia PM, Beilman GJ, SantaCruz KS. A Novel Preclinical Model of Moderate Primary Blast-Induced Traumatic Brain Injury. J Neurotrauma 2015; 32:1109-16. [DOI: 10.1089/neu.2014.3686] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Afshin A. Divani
- Department of Neurology, University of Minnesota, Minneapolis, Minnesota
- Department of Neurosurgery, University of Minnesota, Minneapolis, Minnesota
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota
| | - Amanda J. Murphy
- Department of Neurology, University of Minnesota, Minneapolis, Minnesota
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota
| | - Joyce Meints
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota
| | - Homayoun Sadeghi-Bazargani
- Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Public Health Sciences, Karolinska Institute, Stockholm, Sweden
| | - Jessica Nordberg
- Department of Neurology, University of Minnesota, Minneapolis, Minnesota
| | - Manoj Monga
- Department of Urology, Cleveland Clinic, Cleveland, Ohio
| | - Walter C. Low
- Department of Neurosurgery, University of Minnesota, Minneapolis, Minnesota
| | - Prerana M. Bhatia
- Department of Neurology, University of Minnesota, Minneapolis, Minnesota
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota
| | - Greg J. Beilman
- Department of Surgery, University of Minnesota, Minneapolis, Minnesota
| | - Karen S. SantaCruz
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico
| |
Collapse
|
34
|
Young L, Rule GT, Bocchieri RT, Walilko TJ, Burns JM, Ling G. When physics meets biology: low and high-velocity penetration, blunt impact, and blast injuries to the brain. Front Neurol 2015; 6:89. [PMID: 25999910 PMCID: PMC4423508 DOI: 10.3389/fneur.2015.00089] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 04/09/2015] [Indexed: 12/22/2022] Open
Abstract
The incidence of traumatic brain injuries (TBI) in the US has reached epidemic proportions with well over 2 million new cases reported each year. TBI can occur in both civilians and warfighters, with head injuries occurring in both combat and non-combat situations from a variety of threats, including ballistic penetration, acceleration, blunt impact, and blast. Most generally, TBI is a condition in which physical loads exceed the capacity of brain tissues to absorb without injury. More specifically, TBI results when sufficient external force is applied to the head and is subsequently converted into stresses that must be absorbed or redirected by protective equipment. If the stresses are not sufficiently absorbed or redirected, they will lead to damage of extracranial soft tissue and the skull. Complex interactions and kinematics of the head, neck and jaw cause strains within the brain tissue, resulting in structural, anatomical damage that is characteristic of the inciting insult. This mechanical trauma then initiates a neuro-chemical cascade that leads to the functional consequences of TBI, such as cognitive impairment. To fully understand the mechanisms by which TBI occurs, it is critically important to understand the effects of the loading environments created by these threats. In the following, a review is made of the pertinent complex loading conditions and how these loads cause injury. Also discussed are injury thresholds and gaps in knowledge, both of which are needed to design improved protective systems.
Collapse
Affiliation(s)
- Leanne Young
- Security Engineering and Applied Sciences Sector, Applied Research Associates, Inc., Dallas, TX, USA
- Center for Brain Health, University of Texas at Dallas, Dallas, TX, USA
| | - Gregory T. Rule
- Security Engineering and Applied Sciences Sector, Applied Research Associates, Inc., San Antonio, TX, USA
| | - Robert T. Bocchieri
- Silicon Valley Office, Applied Research Associates, Inc., Los Altos, CA, USA
| | - Timothy J. Walilko
- Rocky Mountain Division, Applied Research Associates, Inc., Littleton, CO, USA
| | - Jennie M. Burns
- Security Engineering and Applied Sciences Sector, Applied Research Associates, Inc., San Antonio, TX, USA
| | - Geoffrey Ling
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| |
Collapse
|
35
|
Abstract
Mild traumatic brain injury (mTBI) includes concussion, subconcussion, and most exposures to explosive blast from improvised explosive devices. mTBI is the most common traumatic brain injury affecting military personnel; however, it is the most difficult to diagnose and the least well understood. It is also recognized that some mTBIs have persistent, and sometimes progressive, long-term debilitating effects. Increasing evidence suggests that a single traumatic brain injury can produce long-term gray and white matter atrophy, precipitate or accelerate age-related neurodegeneration, and increase the risk of developing Alzheimer's disease, Parkinson's disease, and motor neuron disease. In addition, repetitive mTBIs can provoke the development of a tauopathy, chronic traumatic encephalopathy. We found early changes of chronic traumatic encephalopathy in four young veterans of the Iraq and Afghanistan conflict who were exposed to explosive blast and in another young veteran who was repetitively concussed. Four of the five veterans with early-stage chronic traumatic encephalopathy were also diagnosed with posttraumatic stress disorder. Advanced chronic traumatic encephalopathy has been found in veterans who experienced repetitive neurotrauma while in service and in others who were accomplished athletes. Clinically, chronic traumatic encephalopathy is associated with behavioral changes, executive dysfunction, memory loss, and cognitive impairments that begin insidiously and progress slowly over decades. Pathologically, chronic traumatic encephalopathy produces atrophy of the frontal and temporal lobes, thalamus, and hypothalamus; septal abnormalities; and abnormal deposits of hyperphosphorylated tau as neurofibrillary tangles and disordered neurites throughout the brain. The incidence and prevalence of chronic traumatic encephalopathy and the genetic risk factors critical to its development are currently unknown. Chronic traumatic encephalopathy has clinical and pathological features that overlap with postconcussion syndrome and posttraumatic stress disorder, suggesting that the three disorders might share some biological underpinnings.
Collapse
|
36
|
Elder GA, Gama Sosa MA, De Gasperi R, Stone JR, Dickstein DL, Haghighi F, Hof PR, Ahlers ST. Vascular and inflammatory factors in the pathophysiology of blast-induced brain injury. Front Neurol 2015; 6:48. [PMID: 25852632 PMCID: PMC4360816 DOI: 10.3389/fneur.2015.00048] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 02/23/2015] [Indexed: 11/13/2022] Open
Abstract
Blast-related traumatic brain injury (TBI) has received much recent attention because of its frequency in the conflicts in Iraq and Afghanistan. This renewed interest has led to a rapid expansion of clinical and animal studies related to blast. In humans, high-level blast exposure is associated with a prominent hemorrhagic component. In animal models, blast exerts a variety of effects on the nervous system including vascular and inflammatory effects that can be seen with even low-level blast exposures which produce minimal or no neuronal pathology. Acutely, blast exposure in animals causes prominent vasospasm and decreased cerebral blood flow along with blood-brain barrier breakdown and increased vascular permeability. Besides direct effects on the central nervous system, evidence supports a role for a thoracically mediated effect of blast; whereby, pressure waves transmitted through the systemic circulation damage the brain. Chronically, a vascular pathology has been observed that is associated with alterations of the vascular extracellular matrix. Sustained microglial and astroglial reactions occur after blast exposure. Markers of a central and peripheral inflammatory response are found for sustained periods after blast injury and include elevation of inflammatory cytokines and other inflammatory mediators. At low levels of blast exposure, a microvascular pathology has been observed in the presence of an otherwise normal brain parenchyma, suggesting that the vasculature may be selectively vulnerable to blast injury. Chronic immune activation in brain following vascular injury may lead to neurobehavioral changes in the absence of direct neuronal pathology. Strategies aimed at preventing or reversing vascular damage or modulating the immune response may improve the chronic neuropsychiatric symptoms associated with blast-related TBI.
Collapse
Affiliation(s)
- Gregory A Elder
- Neurology Service, James J. Peters Department of Veterans Affairs Medical Center , Bronx, NY , USA ; Department of Psychiatry, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Department of Neurology, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai , New York, NY , USA
| | - Miguel A Gama Sosa
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center , Bronx, NY , USA
| | - Rita De Gasperi
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center , Bronx, NY , USA
| | - James Radford Stone
- Department of Radiology and Medical Imaging, University of Virginia , Charlottesville, VA , USA ; Department of Neurosurgery, University of Virginia , Charlottesville, VA , USA
| | - Dara L Dickstein
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Department of Geriatrics and Palliative Care, Icahn School of Medicine at Mount Sinai , New York, NY , USA
| | - Fatemeh Haghighi
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Research and Development Service, James J. Peters Department of Veterans Affairs Medical Center , Bronx, NY , USA ; Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai , New York, NY , USA
| | - Patrick R Hof
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai , New York, NY , USA ; Department of Geriatrics and Palliative Care, Icahn School of Medicine at Mount Sinai , New York, NY , USA
| | - Stephen T Ahlers
- Department of Neurotrauma, Operational and Undersea Medicine Directorate, Naval Medical Research Center , Silver Spring, MD , USA
| |
Collapse
|
37
|
A Physical Head and Neck Surrogate Model to Investigate Blast-Induced Mild Traumatic Brain Injury. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2015. [DOI: 10.1007/s13369-015-1583-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
38
|
Relation of Repeated Low-Level Blast Exposure With Symptomology Similar to Concussion. J Head Trauma Rehabil 2015; 30:47-55. [DOI: 10.1097/htr.0000000000000064] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
39
|
Elder GA, Stone JR, Ahlers ST. Effects of low-level blast exposure on the nervous system: is there really a controversy? Front Neurol 2014; 5:269. [PMID: 25566175 PMCID: PMC4271615 DOI: 10.3389/fneur.2014.00269] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 11/29/2014] [Indexed: 12/20/2022] Open
Abstract
High-pressure blast waves can cause extensive CNS injury in human beings. However, in combat settings, such as Iraq and Afghanistan, lower level exposures associated with mild traumatic brain injury (mTBI) or subclinical exposure have been much more common. Yet controversy exists concerning what traits can be attributed to low-level blast, in large part due to the difficulty of distinguishing blast-related mTBI from post-traumatic stress disorder (PTSD). We describe how TBI is defined in human beings and the problems posed in using current definitions to recognize blast-related mTBI. We next consider the problem of applying definitions of human mTBI to animal models, in particular that TBI severity in human beings is defined in relation to alteration of consciousness at the time of injury, which typically cannot be assessed in animals. However, based on outcome assessments, a condition of "low-level" blast exposure can be defined in animals that likely approximates human mTBI or subclinical exposure. We review blast injury modeling in animals noting that inconsistencies in experimental approach have contributed to uncertainty over the effects of low-level blast. Yet, animal studies show that low-level blast pressure waves are transmitted to the brain. In brain, low-level blast exposures cause behavioral, biochemical, pathological, and physiological effects on the nervous system including the induction of PTSD-related behavioral traits in the absence of a psychological stressor. We review the relationship of blast exposure to chronic neurodegenerative diseases noting the paradoxical lowering of Abeta by blast, which along with other observations suggest that blast-related TBI is pathophysiologically distinct from non-blast TBI. Human neuroimaging studies show that blast-related mTBI is associated with a variety of chronic effects that are unlikely to be explained by co-morbid PTSD. We conclude that abundant evidence supports low-level blast as having long-term effects on the nervous system.
Collapse
Affiliation(s)
- Gregory A. Elder
- Neurology Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - James R. Stone
- Department of Radiology, University of Virginia, Charlottesville, VA, USA
- Department of Neurosurgery, University of Virginia, Charlottesville, VA, USA
| | - Stephen T. Ahlers
- Department of Neurotrauma, Operational and Undersea Medicine Directorate, Naval Medical Research Center, Silver Spring, MD, USA
| |
Collapse
|
40
|
Wang C, Pahk JB, Balaban CD, Miller MC, Wood AR, Vipperman JS. Computational study of human head response to primary blast waves of five levels from three directions. PLoS One 2014; 9:e113264. [PMID: 25409326 PMCID: PMC4237386 DOI: 10.1371/journal.pone.0113264] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 10/02/2014] [Indexed: 11/17/2022] Open
Abstract
Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI). To investigate the mechanical response of human brain to primary blast waves and to identify the injury mechanisms of bTBI, a three-dimensional finite element head model consisting of the scalp, skull, cerebrospinal fluid, nasal cavity, and brain was developed from the imaging data set of a human female. The finite element head model was partially validated and was subjected to the blast waves of five blast intensities from the anterior, right lateral, and posterior directions at a stand-off distance of one meter from the detonation center. Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue. Intracranial pressure (ICP) is predicted to have the highest magnitude from a posterior blast wave in comparison with a blast wave from any of the other two directions with same blast intensity. The brain model predicts higher positive pressure at the site proximal to blast wave than that at the distal site. The intracranial pressure wave invariably travels into the posterior fossa and vertebral column, causing high pressures in these regions. The severities of cerebral contusions at different cerebral locations are estimated using an ICP based injury criterion. Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma. According to an axonal injury criterion based on von Mises stress, axonal injury is not predicted to be a cause of primary brain injury from blasts.
Collapse
Affiliation(s)
- Chenzhi Wang
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jae Bum Pahk
- Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Carey D. Balaban
- University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Mark C. Miller
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Adam R. Wood
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jeffrey S. Vipperman
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| |
Collapse
|
41
|
Scaling in neurotrauma: How do we apply animal experiments to people? Exp Neurol 2014; 261:120-6. [DOI: 10.1016/j.expneurol.2014.07.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 06/26/2014] [Accepted: 07/02/2014] [Indexed: 12/19/2022]
|
42
|
Goldstein LE, McKee AC, Stanton PK. Considerations for animal models of blast-related traumatic brain injury and chronic traumatic encephalopathy. Alzheimers Res Ther 2014; 6:64. [PMID: 25478023 PMCID: PMC4255537 DOI: 10.1186/s13195-014-0064-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The association of military blast exposure and brain injury was first appreciated in World War I as commotio cerebri, and later as shell shock. Similar injuries sustained in modern military conflicts are now classified as mild traumatic brain injury (TBI). Recent research has yielded new insights into the mechanisms by which blast exposure leads to acute brain injury and chronic sequelae, including postconcussive syndrome, post-traumatic stress disorder, post-traumatic headache, and chronic traumatic encephalopathy, a tau protein neurodegenerative disease. Impediments to delivery of effective medical care for individuals affected by blast-related TBI include: poor insight into the heterogeneity of neurological insults induced by blast exposure; limited understanding of the mechanisms by which blast exposure injures the brain and triggers sequelae; failure to appreciate interactive injuries that affect frontal lobe function, pituitary regulation, and neurovegetative homeostasis; unknown influence of genetic risk factors, prior trauma, and comorbidities; absence of validated diagnostic criteria and clinical nosology that differentiate clinical endophenotypes; and lack of empirical evidence to guide medical management and therapeutic intervention. While clinicopathological analysis can provide evidence of correlative association, experimental use of animal models remains the primary tool for establishing causal mechanisms of disease. However, the TBI field is confronted by a welter of animal models with varying clinical relevance, thereby impeding scientific coherence and hindering translational progress. Animal models of blast TBI will be far more translationally useful if experimental emphasis focuses on accurate reproduction of clinically relevant endpoints (output) rather than scaled replication of idealized blast shockwaves (input). The utility of an animal model is dependent on the degree to which the model recapitulates pathophysiological mechanisms, neuropathological features, and neurological sequelae observed in the corresponding human disorder. Understanding the purpose of an animal model and the criteria by which experimental results derived from the model are validated are critical components for useful animal modeling. Animal models that reliably demonstrate clinically relevant endpoints will expedite development of new treatments, diagnostics, preventive measures, and rehabilitative strategies for individuals affected by blast TBI and its aftermath.
Collapse
Affiliation(s)
- Lee E Goldstein
- Boston University School of Medicine and College of Engineering, 670 Albany Street, 4th Floor, Boston 02118, MA, USA
- Boston University Alzheimer’s Disease Center, Boston University School of Medicine, Robinson Hall, 7th Floor, Boston 02118, MA, USA
| | - Ann C McKee
- Boston University Alzheimer’s Disease Center, Boston University School of Medicine, Robinson Hall, 7th Floor, Boston 02118, MA, USA
- US Department of Veterans Affairs, VA Boston Healthcare System, 150 South Huntington Avenue, Boston 02130, MA, USA
| | - Patric K Stanton
- Departments of Neurology, Cell Biology & Anatomy, New York Medical College, Basic Science Building, Rm 217, Valhalla 10595, NY, USA
| |
Collapse
|
43
|
Shetty AK, Mishra V, Kodali M, Hattiangady B. Blood brain barrier dysfunction and delayed neurological deficits in mild traumatic brain injury induced by blast shock waves. Front Cell Neurosci 2014; 8:232. [PMID: 25165433 PMCID: PMC4131244 DOI: 10.3389/fncel.2014.00232] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 07/24/2014] [Indexed: 11/13/2022] Open
Abstract
Mild traumatic brain injury (mTBI) resulting from exposure to blast shock waves (BSWs) is one of the most predominant causes of illnesses among veterans who served in the recent Iraq and Afghanistan wars. Such mTBI can also happen to civilians if exposed to shock waves of bomb attacks by terrorists. While cognitive problems, memory dysfunction, depression, anxiety and diffuse white matter injury have been observed at both early and/or delayed time-points, an initial brain pathology resulting from exposure to BSWs appears to be the dysfunction or disruption of the blood-brain barrier (BBB). Studies in animal models suggest that exposure to relatively milder BSWs (123 kPa) initially induces free radical generating enzymes in and around brain capillaries, which enhances oxidative stress resulting in loss of tight junction (TJ) proteins, edema formation, and leakiness of BBB with disruption or loss of its components pericytes and astrocyte end-feet. On the other hand, exposure to more intense BSWs (145-323 kPa) causes acute disruption of the BBB with vascular lesions in the brain. Both of these scenarios lead to apoptosis of endothelial and neural cells and neuroinflammation in and around capillaries, which may progress into chronic traumatic encephalopathy (CTE) and/or a variety of neurological impairments, depending on brain regions that are afflicted with such lesions. This review discusses studies that examined alterations in the brain milieu causing dysfunction or disruption of the BBB and neuroinflammation following exposure to different intensities of BSWs. Furthermore, potential of early intervention strategies capable of easing oxidative stress, repairing the BBB or blocking inflammation for minimizing delayed neurological deficits resulting from exposure to BSWs is conferred.
Collapse
Affiliation(s)
- Ashok K Shetty
- Texas A&M Health Science Center College of Medicine at Scott & White, Institute for Regenerative Medicine Temple, TX, USA ; Department of Molecular and Cellular Medicine, Texas A&M Health Science Center College of Medicine College Station, TX, USA ; Research Service, Olin E. Teague Veterans Affairs Medical Center, Central Texas Veterans Health Care System Temple, TX, USA
| | - Vikas Mishra
- Texas A&M Health Science Center College of Medicine at Scott & White, Institute for Regenerative Medicine Temple, TX, USA ; Department of Molecular and Cellular Medicine, Texas A&M Health Science Center College of Medicine College Station, TX, USA ; Research Service, Olin E. Teague Veterans Affairs Medical Center, Central Texas Veterans Health Care System Temple, TX, USA
| | - Maheedhar Kodali
- Texas A&M Health Science Center College of Medicine at Scott & White, Institute for Regenerative Medicine Temple, TX, USA ; Department of Molecular and Cellular Medicine, Texas A&M Health Science Center College of Medicine College Station, TX, USA ; Research Service, Olin E. Teague Veterans Affairs Medical Center, Central Texas Veterans Health Care System Temple, TX, USA
| | - Bharathi Hattiangady
- Texas A&M Health Science Center College of Medicine at Scott & White, Institute for Regenerative Medicine Temple, TX, USA ; Department of Molecular and Cellular Medicine, Texas A&M Health Science Center College of Medicine College Station, TX, USA ; Research Service, Olin E. Teague Veterans Affairs Medical Center, Central Texas Veterans Health Care System Temple, TX, USA
| |
Collapse
|
44
|
Gama Sosa MA, De Gasperi R, Janssen PL, Yuk FJ, Anazodo PC, Pricop PE, Paulino AJ, Wicinski B, Shaughness MC, Maudlin-Jeronimo E, Hall AA, Dickstein DL, McCarron RM, Chavko M, Hof PR, Ahlers ST, Elder GA. Selective vulnerability of the cerebral vasculature to blast injury in a rat model of mild traumatic brain injury. Acta Neuropathol Commun 2014; 2:67. [PMID: 24938728 PMCID: PMC4229875 DOI: 10.1186/2051-5960-2-67] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 06/03/2014] [Indexed: 12/23/2022] Open
Abstract
Background Blast-related traumatic brain injury (TBI) is a common cause of injury in the military operations in Iraq and Afghanistan. How the primary blast wave affects the brain is not well understood. The aim of the present study was to examine whether blast exposure affects the cerebral vasculature in a rodent model. We analyzed the brains of rats exposed to single or multiple (three) 74.5 kPa blast exposures, conditions that mimic a mild TBI. Rats were sacrificed 24 hours or between 6 and 10 months after exposure. Blast-induced cerebral vascular pathology was examined by a combination of light microscopy, immunohistochemistry, and electron microscopy. Results We describe a selective vascular pathology that is present acutely at 24 hours after injury. The vascular pathology is found at the margins of focal shear-related injuries that, as we previously showed, typically follow the patterns of penetrating cortical vessels. However, changes in the microvasculature extend beyond the margins of such lesions. Electron microscopy revealed that microvascular pathology is found in regions of the brain with an otherwise normal neuropil. This initial injury leads to chronic changes in the microvasculature that are still evident many months after the initial blast exposure. Conclusions These studies suggest that vascular pathology may be a central mechanism in the induction of chronic blast-related injury.
Collapse
|
45
|
Simard JM, Pampori A, Keledjian K, Tosun C, Schwartzbauer G, Ivanova S, Gerzanich V. Exposure of the thorax to a sublethal blast wave causes a hydrodynamic pulse that leads to perivenular inflammation in the brain. J Neurotrauma 2014; 31:1292-304. [PMID: 24673157 DOI: 10.1089/neu.2013.3016] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traumatic brain injury (TBI) caused by an explosive blast (blast-TBI) is postulated to result, in part, from transvascular transmission to the brain of a hydrodynamic pulse (a.k.a., volumetric blood surge, ballistic pressure wave, hydrostatic shock, or hydraulic shock) induced in major intrathoracic blood vessels. This mechanism of blast-TBI has not been demonstrated directly. We tested the hypothesis that a blast wave impacting the thorax would induce a hydrodynamic pulse that would cause pathological changes in the brain. We constructed a Thorax-Only Blast Injury Apparatus (TOBIA) and a Jugular-Only Blast Injury Apparatus (JOBIA). TOBIA delivered a collimated blast wave to the right lateral thorax of a rat, precluding direct impact on the cranium. JOBIA delivered a blast wave to the fluid-filled port of an extracorporeal intravenous infusion device whose catheter was inserted retrograde into the jugular vein, precluding lung injury. Long Evans rats were subjected to sublethal injury by TOBIA or JOBIA. Blast injury induced by TOBIA was characterized by apnea and diffuse bilateral hemorrhagic injury to the lungs associated with a transient reduction in pulse oximetry signals. Immunolabeling 24 h after injury by TOBIA showed up-regulation of tumor necrosis factor alpha, ED-1, sulfonylurea receptor 1 (Sur1), and glial fibrillary acidic protein in veins or perivenular tissues and microvessels throughout the brain. The perivenular inflammatory effects induced by TOBIA were prevented by ligating the jugular vein and were reproduced using JOBIA. We conclude that blast injury to the thorax leads to perivenular inflammation, Sur1 up-regulation, and reactive astrocytosis resulting from the induction of a hydrodynamic pulse in the vasculature.
Collapse
Affiliation(s)
- J Marc Simard
- 1 Department of Neurosurgery, University of Maryland School of Medicine , Baltimore, Maryland
| | | | | | | | | | | | | |
Collapse
|
46
|
Combes RD. A critical review of anaesthetised animal models and alternatives for military research, testing and training, with a focus on blast damage, haemorrhage and resuscitation. Altern Lab Anim 2014; 41:385-415. [PMID: 24329746 DOI: 10.1177/026119291304100508] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Military research, testing, and surgical and resuscitation training, are aimed at mitigating the consequences of warfare and terrorism to armed forces and civilians. Traumatisation and tissue damage due to explosions, and acute loss of blood due to haemorrhage, remain crucial, potentially preventable, causes of battlefield casualties and mortalities. There is also the additional threat from inhalation of chemical and aerosolised biological weapons. The use of anaesthetised animal models, and their respective replacement alternatives, for military purposes -- particularly for blast injury, haemorrhaging and resuscitation training -- is critically reviewed. Scientific problems with the animal models include the use of crude, uncontrolled and non-standardised methods for traumatisation, an inability to model all key trauma mechanisms, and complex modulating effects of general anaesthesia on target organ physiology. Such effects depend on the anaesthetic and influence the cardiovascular system, respiration, breathing, cerebral haemodynamics, neuroprotection, and the integrity of the blood-brain barrier. Some anaesthetics also bind to the NMDA brain receptor with possible differential consequences in control and anaesthetised animals. There is also some evidence for gender-specific effects. Despite the fact that these issues are widely known, there is little published information on their potential, at best, to complicate data interpretation and, at worst, to invalidate animal models. There is also a paucity of detail on the anaesthesiology used in studies, and this can hinder correct data evaluation. Welfare issues relate mainly to the possibility of acute pain as a side-effect of traumatisation in recovered animals. Moreover, there is the increased potential for animals to suffer when anaesthesia is temporary, and the procedures invasive. These dilemmas can be addressed, however, as a diverse range of replacement approaches exist, including computer and mathematical dynamic modelling of the human body, cadavers, interactive human patient simulators for training, in vitro techniques involving organotypic cultures of target organs, and epidemiological and clinical studies. While the first four of these have long proven useful for developing protective measures and predicting the consequences of trauma, and although many phenomena and their sequelae arising from different forms of trauma in vivo can be induced and reproduced in vitro, non-animal approaches require further development, and their validation and use need to be coordinated and harmonised. Recommendations to these ends are proposed, and the scientific and welfare problems associated with animal models are addressed, with the future focus being on the use of batteries of complementary replacement methods deployed in integrated strategies, and on greater transparency and scientific cooperation.
Collapse
|
47
|
Zhu F, Chou CC, Yang KH, King AI. A theoretical analysis of stress wave propagation in the head under primary blast loading. Proc Inst Mech Eng H 2014; 228:439-445. [PMID: 24718865 DOI: 10.1177/0954411914530882] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Traumatic brain injury due to primary blast loading has become a signature injury in recent military conflicts. Efforts have been made to study the stress wave propagation in the head. However, the relationship of incident pressure, reflected pressure and intracranial pressure is still not clear, and the experimental findings reported in the literature are contradictory. In this article, an analytical model is developed to calculate the stress wave transfer through a multiple-layered structure which is used to mimic the head. The model predicts stress at the scalp-skull and skull-brain interfaces as the functions of reflected pressure, which is further dependent on incident pressure. A numerical model is used to corroborate the theoretical predictions. It is concluded that scalp has an amplification effect on intracranial pressure. If scalp is absent, there exists a critical incident pressure, defined as P cr at approximately 16 kPa. When peak incident pressure σ in is higher than 16 kPa, the pressure at the skull-brain interface is greater than σ in; otherwise, it is lower than σ in.
Collapse
Affiliation(s)
- Feng Zhu
- Bioengineering Center, Wayne State University, Detroit, MI, USA
| | - Clifford C Chou
- Bioengineering Center, Wayne State University, Detroit, MI, USA
| | - King H Yang
- Bioengineering Center, Wayne State University, Detroit, MI, USA
| | - Albert I King
- Bioengineering Center, Wayne State University, Detroit, MI, USA
| |
Collapse
|
48
|
Kovacs SK, Leonessa F, Ling GSF. Blast TBI Models, Neuropathology, and Implications for Seizure Risk. Front Neurol 2014; 5:47. [PMID: 24782820 PMCID: PMC3988378 DOI: 10.3389/fneur.2014.00047] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 03/26/2014] [Indexed: 12/31/2022] Open
Abstract
Traumatic brain injury (TBI) due to explosive blast exposure is a leading combat casualty. It is also implicated as a key contributor to war related mental health diseases. A clinically important consequence of all types of TBI is a high risk for development of seizures and epilepsy. Seizures have been reported in patients who have suffered blast injuries in the Global War on Terror but the exact prevalence is unknown. The occurrence of seizures supports the contention that explosive blast leads to both cellular and structural brain pathology. Unfortunately, the exact mechanism by which explosions cause brain injury is unclear, which complicates development of meaningful therapies and mitigation strategies. To help improve understanding, detailed neuropathological analysis is needed. For this, histopathological techniques are extremely valuable and indispensable. In the following we will review the pathological results, including those from immunohistochemical and special staining approaches, from recent preclinical explosive blast studies.
Collapse
Affiliation(s)
- S Krisztian Kovacs
- Laboratory of Neurotrauma, Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, MD , USA
| | - Fabio Leonessa
- Laboratory of Neurotrauma, Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, MD , USA
| | - Geoffrey S F Ling
- Laboratory of Neurotrauma, Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, MD , USA
| |
Collapse
|
49
|
Singh D, Cronin DS, Haladuick TN. Head and brain response to blast using sagittal and transverse finite element models. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2014; 30:470-489. [PMID: 24293124 DOI: 10.1002/cnm.2612] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 10/08/2013] [Accepted: 10/12/2013] [Indexed: 06/02/2023]
Abstract
Mild traumatic brain injury caused by blast exposure from Improvised Explosive Devices has become increasingly prevalent in modern conflicts. To investigate head kinematics and brain tissue response in blast scenarios, two solid hexahedral blast-head models were developed in the sagittal and transverse planes. The models were coupled to an Arbitrary Lagrangian-Eulerian model of the surrounding air to model blast-head interaction, for three blast load cases (5 kg C4 at 3, 3.5 and 4 m). The models were validated using experimental kinematic data, where predicted accelerations were in good agreement with experimental tests, and intracranial pressure traces at four locations in the brain, where the models provided good predictions for frontal, temporal and parietal, but underpredicted pressures at the occipital location. Brain tissue response was investigated for the wide range of constitutive properties available. The models predicted relatively low peak principal brain tissue strains from 0.035 to 0.087; however, strain rates ranged from 225 to 571 s-1. Importantly, these models have allowed us to quantify expected strains and strain rates experienced in brain tissue, which can be used to guide future material characterization. These computationally efficient and predictive models can be used to evaluate protection and mitigation strategies in future analysis.
Collapse
|
50
|
Hue CD, Cao S, Dale Bass CR, Meaney DF, Morrison B. Repeated primary blast injury causes delayed recovery, but not additive disruption, in an in vitro blood-brain barrier model. J Neurotrauma 2014; 31:951-60. [PMID: 24372353 DOI: 10.1089/neu.2013.3149] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recent studies have demonstrated increased susceptibility to breakdown of the cerebral vasculature associated with repetitive traumatic brain injury. We hypothesized that exposure to two consecutive blast injuries would result in exacerbated damage to an in vitro model of the blood-brain barrier (BBB) compared with exposure to a single blast of the same severity. Contrary to our hypothesis, however, repeated mild or moderate primary blast delivered with a 24 or 72 h interval between injuries did not significantly exacerbate reductions in transendothelial electrical resistance (TEER) across a brain endothelial monolayer compared with sister cultures receiving a single exposure of the same intensity. Permeability of the barrier to a range of different-sized solutes remained unaltered after single and repeated blast, supporting that the effects of repeated blast on BBB integrity were not additive. Single blast exposure significantly reduced immunostaining of ZO-1 and claudin-5 tight junction proteins, but subsequent exposure did not cause additional damage to tight junctions. Although repeated blast did not further reduce TEER, the second exposure delayed TEER recovery in BBB cultures. Similarly, recovery of hydraulic conductivity through the BBB was delayed by a second exposure. Extending the interinjury interval to 72 h, the effects of multiple injuries on the BBB were found to be independent given sufficient recovery time between consecutive exposures. Careful investigation of the effects of repeated blast on the BBB will help identify injury levels and a temporal window of vulnerability associated with BBB dysfunction, ultimately leading to improved strategies for protecting warfighters against repeated blast-induced disruption of the cerebral vasculature.
Collapse
Affiliation(s)
- Christopher D Hue
- 1 Department of Biomedical Engineering, Columbia University , New York, New York
| | | | | | | | | |
Collapse
|