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Kommireddy RS, Mehra S, Pompilus M, Arja RD, Zhu T, Yang Z, Fu Y, Zhu J, Kobeissy F, Wang KKW, Febo M. Functional connectivity, tissue microstructure and T2 at 11.1 Tesla distinguishes neuroadaptive differences in two traumatic brain injury models in rats: A Translational Outcomes Project in NeuroTrauma (TOP-NT) UG3 phase study. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.10.570975. [PMID: 38168381 PMCID: PMC10760004 DOI: 10.1101/2023.12.10.570975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
The damage caused by contusive traumatic brain injuries (TBIs) is thought to involve breakdown in neuronal communication through focal and diffuse axonal injury along with alterations to the neuronal chemical environment, which adversely affects neuronal networks beyond the injury epicenter(s). In the present study, functional connectivity along with brain tissue microstructure coupled with T2 relaxometry were assessed in two experimental TBI models in rat, controlled cortical impact (CCI) and lateral fluid percussive injury (LFPI). Rats were scanned on an 11.1 Tesla scanner on days 2 and 30 following either CCI or LFPI. Naive controls were scanned once and used as a baseline comparison for both TBI groups. Scanning included functional magnetic resonance imaging (fMRI), diffusion weighted images (DWI), and multi-echo T2 images. fMRI scans were analyzed for functional connectivity across laterally and medially located region of interests (ROIs) across the cortical mantle, hippocampus, and dorsal striatum. DWI scans were processed to generate maps of fractional anisotropy, mean, axial, and radial diffusivities (FA, MD, AD, RD). The analyses focused on cortical and white matter (WM) regions at or near the TBI epicenter. Our results indicate that rats exposed to CCI and LFPI had significantly increased contralateral intra-cortical connectivity at 2 days post-injury. This was observed across similar areas of the cortex in both groups. The increased contralateral connectivity was still observed by day 30 in CCI, but not LFPI rats. Although both CCI and LFPI had changes in WM and cortical FA and diffusivities, WM changes were most predominant in CCI and cortical changes in LFPI. Our results provide support for the use of multimodal MR imaging for different types of contusive and skull-penetrating injury.
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Kalyani P, Lippa SM, Werner JK, Amyot F, Moore CB, Kenney K, Diaz-Arrastia R. Phosphodiesterase-5 (PDE-5) Inhibitors as Therapy for Cerebrovascular Dysfunction in Chronic Traumatic Brain Injury. Neurotherapeutics 2023; 20:1629-1640. [PMID: 37697134 PMCID: PMC10684467 DOI: 10.1007/s13311-023-01430-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2023] [Indexed: 09/13/2023] Open
Abstract
Multiple phase III randomized controlled trials (RCTs) for pharmacologic interventions in traumatic brain injury (TBI) have failed despite promising results in experimental models. The heterogeneity of TBI, in terms of pathomechanisms and impacted brain structures, likely contributes to these failures. Biomarkers have been recommended to identify patients with relevant pathology (predictive biomarkers) and confirm target engagement and monitor therapy response (pharmacodynamic biomarkers). Our group focuses on traumatic cerebrovascular injury as an understudied endophenotype of TBI and is validating a predictive and pharmacodynamic imaging biomarker (cerebrovascular reactivity; CVR) in moderate-severe TBI. We aim to extend these studies to milder forms of TBI to determine the optimal dose of sildenafil for maximal improvement in CVR. We will conduct a phase II dose-finding study involving 160 chronic TBI patients (mostly mild) using three doses of sildenafil, a phosphodiesterase-5 (PDE-5) inhibitor. The study measures baseline CVR and evaluates the effect of escalating sildenafil doses on CVR improvement. A 4-week trial of thrice daily sildenafil will assess safety, tolerability, and clinical efficacy. This dual-site 4-year study, funded by the Department of Defense and registered in ClinicalTrials.gov (NCT05782244), plans to launch in June 2023. Biomarker-informed RCTs are essential for developing effective TBI interventions, relying on an understanding of underlying pathomechanisms. Traumatic microvascular injury (TMVI) is an attractive mechanism which can be targeted by vaso-active drugs such as PDE-5 inhibitors. CVR is a potential predictive and pharmacodynamic biomarker for targeted interventions aimed at TMVI. (Trial registration: NCT05782244, ClinicalTrials.gov ).
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Affiliation(s)
- Priyanka Kalyani
- Department of Neurology, University of Pennsylvania, 3400 Spruce St, Philadelphia, PA, 19104, USA.
| | - Sara M Lippa
- Walter Reed National Military Medical Center, The National Intrepid Center of Excellence, Palmer Rd S, Bethesda, MD, 20814, USA
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - J Kent Werner
- Walter Reed National Military Medical Center, The National Intrepid Center of Excellence, Palmer Rd S, Bethesda, MD, 20814, USA
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - Franck Amyot
- Walter Reed National Military Medical Center, The National Intrepid Center of Excellence, Palmer Rd S, Bethesda, MD, 20814, USA
| | - Carol B Moore
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - Kimbra Kenney
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - Ramon Diaz-Arrastia
- Department of Neurology, University of Pennsylvania, 3400 Spruce St, Philadelphia, PA, 19104, USA
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3
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Wang Y, Bartels HM, Nelson LD. A Systematic Review of ASL Perfusion MRI in Mild TBI. Neuropsychol Rev 2023; 33:160-191. [PMID: 32808244 PMCID: PMC7889778 DOI: 10.1007/s11065-020-09451-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 08/06/2020] [Indexed: 01/06/2023]
Abstract
Mild traumatic brain injury (mTBI) is a major public health concern. Cerebrovascular alterations play a significant role in the evolution of injury sequelae and in the process of post-traumatic brain repair. Arterial spin labeling (ASL) is an advanced perfusion magnetic resonance imaging technique that permits noninvasive quantification of cerebral blood flow (CBF). This is the first systematic review of ASL research findings in patients with mTBI. Our approach followed the American Academy of Neurology (AAN) and PRISMA guidelines. We searched Ovid/MEDLINE, Web of Science, Scopus, and the Cochrane Index for relevant articles published as of February 20, 2020. Full-text results were combined into Rayyan software for further evaluation. Data extraction, including risk of bias ratings, was performed using American Academy of Neurology's four-tiered classification scheme. Twenty-three articles met inclusion criteria comprising data on up to 566 mTBI patients and 654 control subjects. Of the 23 studies, 18 reported some type of regional CBF abnormality in mTBI patients at rest or during a cognitive task, with more findings of decreased than increased CBF. The evidence supports the conclusion that mTBI likely causes ASL-derived CBF anomalies. However, synthesis of findings was challenging due to substantial methodological variations across studies and few studies with low risk of bias. Thus, larger-scale prospective cohort studies are needed to more definitively chart the course of CBF changes in humans after mTBI and to understand how individual difference factors contribute to post-injury CBF changes.
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Affiliation(s)
- Yang Wang
- Department of Radiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA.
| | - Hannah M Bartels
- Department of Neurosurgery, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI, 53226, USA
| | - Lindsay D Nelson
- Department of Neurosurgery, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI, 53226, USA
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4
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Meyer S, Hummel R, Neulen A, Hirnet T, Thal SC. Influence of traumatic brain injury on ipsilateral and contralateral cortical perfusion in mice. Neurosci Lett 2023; 795:137047. [PMID: 36603737 DOI: 10.1016/j.neulet.2023.137047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/28/2022] [Accepted: 01/01/2023] [Indexed: 01/04/2023]
Abstract
Traumatic brain injury (TBI) is one of the most important causes of death in young adults. After brain injury cortical perfusion is impaired by cortical spreading depression, cerebral microvasospasm or microvascular thrombosis and contributes to secondary expansion of lesion into surrounding healthy brain tissue. The present study was designed to determine the regional cortical perfusion pattern after experimental TBI induced by controlled cortical impact (CCI) in male C57/BL6N mice. We performed a longitudinal time series analysis by Laser speckle contrast imaging (LSCI). Measurements were carried out before, immediately and 24 h after trauma. Immediately after CCI cortical perfusion in the lesion core dropped to 10 % of before injury (baseline; %BL) and to 21-24 %BL in the cortical area surrounding the core. Interestingly, cortical perfusion was also significantly reduced in the contralateral non-injured hemisphere (41-58 %BL) matching the corresponding brain region of the injured hemisphere. 24 h after CCI perfusion of the contralateral hemisphere returned to baseline level in the area corresponding to the lesion core, whereas the lateral area of the parietal cortex was hyperperfused (125 %BL). The lesion core region itself remained severely hypoperfused (18 to 26 %BL) during the observation period. TBI causes a maldistribution of both ipsi- and contralateral cerebral perfusion immediately after trauma, which persist for at least 24 h. Higher perfusion levels in the lesion core 24 h after trauma were associated with increased tissue damage, which supports the role of reperfusion injury for secondary brain damage after TBI.
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Affiliation(s)
- Simon Meyer
- Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University, Langenbeckstraße 1, 55131 Mainz, Germany.
| | - Regina Hummel
- Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University, Langenbeckstraße 1, 55131 Mainz, Germany.
| | - Axel Neulen
- Department of Neurosurgery, University Medical Center of the Johannes Gutenberg-University, Langenbeckstraße 1, 55131 Mainz, Germany.
| | - Tobias Hirnet
- Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University, Langenbeckstraße 1, 55131 Mainz, Germany.
| | - Serge C Thal
- Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University, Langenbeckstraße 1, 55131 Mainz, Germany; Department of Anesthesiology, HELIOS University Hospital Wuppertal, University Witten/Herdecke, Heusnerstraße 40, 42283 Wuppertal, Germany.
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5
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Smith DH, Kochanek PM, Rosi S, Meyer R, Ferland-Beckham C, Prager EM, Ahlers ST, Crawford F. Roadmap for Advancing Pre-Clinical Science in Traumatic Brain Injury. J Neurotrauma 2021; 38:3204-3221. [PMID: 34210174 PMCID: PMC8820284 DOI: 10.1089/neu.2021.0094] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Pre-clinical models of disease have long played important roles in the advancement of new treatments. However, in traumatic brain injury (TBI), despite the availability of numerous model systems, translation from bench to bedside remains elusive. Integrating clinical relevance into pre-clinical model development is a critical step toward advancing therapies for TBI patients across the spectrum of injury severity. Pre-clinical models include in vivo and ex vivo animal work-both small and large-and in vitro modeling. The wide range of pre-clinical models reflect substantial attempts to replicate multiple aspects of TBI sequelae in humans. Although these models reveal multiple putative mechanisms underlying TBI pathophysiology, failures to translate these findings into successful clinical trials call into question the clinical relevance and applicability of the models. Here, we address the promises and pitfalls of pre-clinical models with the goal of evolving frameworks that will advance translational TBI research across models, injury types, and the heterogenous etiology of pathology.
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Affiliation(s)
- Douglas H Smith
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Patrick M Kochanek
- Department of Critical Care Medicine; Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh of UPMC, Rangos Research Center, Pittsburgh, Pennsylvania, USA
| | - Susanna Rosi
- Departments of Physical Therapy Rehabilitation Science, Neurological Surgery, Weill Institute for Neuroscience, University of California San Francisco, Zuckerberg San Francisco General Hospital, San Francisco, California, USA
| | - Retsina Meyer
- Cohen Veterans Bioscience, New York, New York, USA.,Delix Therapeutics, Inc, Boston, Massachusetts, USA
| | | | | | - Stephen T Ahlers
- Department of Neurotrauma, Operational and Undersea Medicine Directorate Naval Medical Research Center, Silver Spring, Maryland, USA
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6
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Iboaya A, Harris JL, Arickx AN, Nudo RJ. Models of Traumatic Brain Injury in Aged Animals: A Clinical Perspective. Neurorehabil Neural Repair 2019; 33:975-988. [PMID: 31722616 PMCID: PMC6920554 DOI: 10.1177/1545968319883879] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Traumatic brain injury (TBI) is a major cause of morbidity and mortality in the United States, with advanced age being one of the major predictors of poor prognosis. To replicate the mechanisms and multifaceted complexities of human TBI and develop prospective therapeutic treatments, various TBI animal models have been developed. These models have been essential in furthering our understanding of the pathophysiology and biochemical effects on brain mechanisms following TBI. Despite these advances, translating preclinical results to clinical application, particularly in elderly individuals, continues to be challenging. This review aims to provide a clinical perspective, identifying relevant variables currently not replicated in TBI animal models, to potentially improve translation to clinical practice, especially as it applies to elderly populations. As background for this clinical perspective, we reviewed articles indexed on PubMed from 1970 to 2019 that used aged animal models for studying TBI. These studies examined end points relevant for clinical translation, such as neurocognitive effects, sensorimotor behavior, physiological mechanisms, and efficacy of neuroprotective therapies. However, compared with the higher incidence of TBI in older individuals, animal studies on the basic science of aging and TBI remain remarkably scarce. Moreover, a fundamental disconnect remains between experiments in animal models of TBI and successful translation of findings for treating the older TBI population. In this article, we aim to provide a clinical perspective on the unique attributes of TBI in older individuals and a critical appraisal of the research to date on TBI in aged animal models as well as recommendations for future studies.
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Affiliation(s)
- Aiwane Iboaya
- University of Kansas Medical Center, Kansas City, KS, USA
| | - Janna L Harris
- University of Kansas Medical Center, Kansas City, KS, USA
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7
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Acute and chronic stage adaptations of vascular architecture and cerebral blood flow in a mouse model of TBI. Neuroimage 2019; 202:116101. [DOI: 10.1016/j.neuroimage.2019.116101] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 08/12/2019] [Accepted: 08/14/2019] [Indexed: 11/18/2022] Open
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8
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Kochanek PM, Dixon CE, Mondello S, Wang KKK, Lafrenaye A, Bramlett HM, Dietrich WD, Hayes RL, Shear DA, Gilsdorf JS, Catania M, Poloyac SM, Empey PE, Jackson TC, Povlishock JT. Multi-Center Pre-clinical Consortia to Enhance Translation of Therapies and Biomarkers for Traumatic Brain Injury: Operation Brain Trauma Therapy and Beyond. Front Neurol 2018; 9:640. [PMID: 30131759 PMCID: PMC6090020 DOI: 10.3389/fneur.2018.00640] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 07/17/2018] [Indexed: 12/15/2022] Open
Abstract
Current approaches have failed to yield success in the translation of neuroprotective therapies from the pre-clinical to the clinical arena for traumatic brain injury (TBI). Numerous explanations have been put forth in both the pre-clinical and clinical arenas. Operation Brain Trauma Therapy (OBTT), a pre-clinical therapy and biomarker screening consortium has, to date, evaluated 10 therapies and assessed three serum biomarkers in nearly 1,500 animals across three rat models and a micro pig model of TBI. OBTT provides a unique platform to exploit heterogeneity of TBI and execute the research needed to identify effective injury specific therapies toward precision medicine. It also represents one of the first multi-center pre-clinical consortia for TBI, and through its work has yielded insight into the challenges and opportunities of this approach. In this review, important concepts related to consortium infrastructure, modeling, therapy selection, dosing and target engagement, outcomes, analytical approaches, reproducibility, and standardization will be discussed, with a focus on strategies to embellish and improve the chances for future success. We also address issues spanning the continuum of care. Linking the findings of optimized pre-clinical consortia to novel clinical trial designs has great potential to help address the barriers in translation and produce successes in both therapy and biomarker development across the field of TBI and beyond.
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Affiliation(s)
- Patrick M. Kochanek
- Safar Center for Resuscitation Research, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - C. Edward Dixon
- Safar Center for Resuscitation Research, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, United States
| | - Stefania Mondello
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
- Oasi Research Institute (IRCCS), Troina, Italy
| | - Kevin K. K. Wang
- Program for Neuroproteomics and Biomarkers Research, Departments of Psychiatry, Neuroscience, and Chemistry, University of Florida, Gainesville, FL, United States
| | - Audrey Lafrenaye
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, United States
| | - Helen M. Bramlett
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, FL, United States
| | - W. Dalton Dietrich
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Ronald L. Hayes
- Center for Innovative Research, Center for Neuroproteomics and Biomarkers Research, Banyan Biomarkers Research, Banyan Biomarkers, Inc., Alachua, FL, United States
| | - Deborah A. Shear
- Brain Trauma Neuroprotection and Neurorestoration Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Janice S. Gilsdorf
- Brain Trauma Neuroprotection and Neurorestoration Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | | | - Samuel M. Poloyac
- Department of Pharmacy and Therapeutics, Center for Clinical Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA, United States
| | - Philip E. Empey
- Department of Pharmacy and Therapeutics, Center for Clinical Pharmaceutical Sciences and the Clinical Translational Science Institute, University of Pittsburgh, Pittsburgh, PA, United States
| | - Travis C. Jackson
- Safar Center for Resuscitation Research, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - John T. Povlishock
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, United States
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9
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Garrett DD, Lindenberger U, Hoge RD, Gauthier CJ. Age differences in brain signal variability are robust to multiple vascular controls. Sci Rep 2017; 7:10149. [PMID: 28860455 PMCID: PMC5579254 DOI: 10.1038/s41598-017-09752-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 07/31/2017] [Indexed: 11/09/2022] Open
Abstract
A host of studies support that younger, better performing adults express greater moment-to-moment blood oxygen level-dependent (BOLD) signal variability (SDBOLD) in various cortical regions, supporting an emerging view that the aging brain may undergo a generalized reduction in dynamic range. However, the exact physiological nature of age differences in SDBOLD remains understudied. In a sample of 29 younger and 45 older adults, we examined the contribution of vascular factors to age group differences in fixation-based SDBOLD using (1) a dual-echo BOLD/pseudo-continuous arterial spin labeling (pCASL) sequence, and (2) hypercapnia via a computer-controlled gas delivery system. We tested the hypothesis that, although SDBOLD may relate to individual differences in absolute cerebral blood flow (CBF), BOLD cerebrovascular reactivity (CVR), or maximum BOLD signal change (M), robust age differences in SDBOLD would remain after multiple statistical controls for these vascular factors. As expected, our results demonstrated that brain regions in which younger adults expressed higher SDBOLD persisted after comprehensive control of vascular effects. Our findings thus further establish BOLD signal variability as an important marker of the aging brain.
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Affiliation(s)
- Douglas D Garrett
- Max Planck UCL Centre for Computational Psychiatry and Ageing Research, Berlin/London, Germany. .,Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany.
| | - Ulman Lindenberger
- Max Planck UCL Centre for Computational Psychiatry and Ageing Research, Berlin/London, Germany.,Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany.,European University Institute, San Domenico di Fiesole (FI), Fiesole, Italy
| | - Richard D Hoge
- Department of Neurology and Neurosurgery, McGill University, Montreal, Canada
| | - Claudine J Gauthier
- Department of Physics, Concordia University, Montreal, Canada.,PERFORM Centre, Concordia University, Montreal, Canada
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10
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Brockman EC, Jackson TC, Dixon CE, Bayɪr H, Clark RSB, Vagni V, Feldman K, Byrd C, Ma L, Hsia C, Kochanek PM. Polynitroxylated Pegylated Hemoglobin-A Novel, Small Volume Therapeutic for Traumatic Brain Injury Resuscitation: Comparison to Whole Blood and Dose Response Evaluation. J Neurotrauma 2017; 34:1337-1350. [PMID: 27869558 PMCID: PMC5385578 DOI: 10.1089/neu.2016.4656] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Resuscitation with polynitroxylated pegylated hemoglobin (PNPH), a pegylated bovine hemoglobin decorated with nitroxides, eliminated the need for fluid administration, reduced intracranial pressure (ICP) and brain edema, and produced neuroprotection in vitro and in vivo versus Lactated Ringer's solution (LR) in experimental traumatic brain injury (TBI) plus hemorrhagic shock (HS). We hypothesized that resuscitation with PNPH would improve acute physiology versus whole blood after TBI+HS and would be safe and effective across a wide dosage range. Anesthetized mice underwent controlled cortical impact and severe HS to mean arterial pressure (MAP) of 25-27 mm Hg for 35 min, then were resuscitated with PNPH, autologous whole blood, or LR. Markers of acute physiology, including mean arterial blood pressure (MAP), heart rate (HR), blood gases/chemistries, and brain oxygenation (PbtO2), were monitored for 90 min on room air followed by 15 min on 100% oxygen. In a second experiment, the protocol was repeated, except mice were resuscitated with PNPH with doses between 2 and 100 mL/kg. ICP and 24 h %-brain water were evaluated. PNPH-resuscitated mice had higher MAP and lower HR post-resuscitation versus blood or LR (p < 0.01). PNPH-resuscitated mice, versus those resuscitated with blood or LR, also had higher pH and lower serum potassium (p < 0.05). Blood-resuscitated mice, however, had higher PbtO2 versus those resuscitated with LR and PNPH, although PNPH had higher PbtO2 versus LR (p < 0.05). PNPH was well tolerated across the dosing range and dramatically reduced fluid requirements in all doses-even 2 or 5 mL/kg (p < 0.001). ICP was significantly lower in PNPH-treated mice for most doses tested versus in LR-treated mice, although %-brain water did not differ between groups. Resuscitation with PNPH, versus resuscitation with LR or blood, improved MAP, HR, and ICP, reduced acidosis and hyperkalemia, and was well tolerated and effective across a wide dosing range, supporting ongoing pre-clinical development of PNPH for TBI resuscitation.
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Affiliation(s)
- Erik C. Brockman
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pennsylvania
- Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania
| | - Travis C. Jackson
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pennsylvania
| | - C. Edward Dixon
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pennsylvania
- Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Hülya Bayɪr
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pennsylvania
- Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania
- Pittsburgh Center for Free Radical and Antioxidant Health, Pittsburgh, Pennsylvania
| | - Robert S. B. Clark
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pennsylvania
- Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania
| | - Vincent Vagni
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pennsylvania
| | - Keri Feldman
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pennsylvania
| | - Catherine Byrd
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pennsylvania
| | - Li Ma
- Department of Physics, Georgia Southern University, Statesboro, Georgia
| | | | - Patrick M. Kochanek
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pennsylvania
- Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania
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11
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Long JA, Watts LT, Li W, Shen Q, Muir ER, Huang S, Boggs RC, Suri A, Duong TQ. The effects of perturbed cerebral blood flow and cerebrovascular reactivity on structural MRI and behavioral readouts in mild traumatic brain injury. J Cereb Blood Flow Metab 2015; 35:1852-61. [PMID: 26104285 PMCID: PMC4635242 DOI: 10.1038/jcbfm.2015.143] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 05/11/2015] [Accepted: 05/22/2015] [Indexed: 12/22/2022]
Abstract
This study investigated the effects of perturbed cerebral blood flow (CBF) and cerebrovascular reactivity (CR) on relaxation time constant (T2), apparent diffusion coefficient (ADC), fractional anisotropy (FA), and behavioral scores at 1 and 3 hours, 2, 7, and 14 days after traumatic brain injury (TBI) in rats. Open-skull TBI was induced over the left primary forelimb somatosensory cortex (N=8 and 3 sham). We found the abnormal areas of CBF and CR on days 0 and 2 were larger than those of the T2, ADC, and FA abnormalities. In the impact core, CBF was reduced on day 0, increased to 2.5 times of normal on day 2, and returned toward normal by day 14, whereas in the tissue surrounding the impact, hypoperfusion was observed on days 0 and 2. CR in the impact core was negative, most severe on day 2 but gradually returned toward normal. T2, ADC, and FA abnormalities in the impact core were detected on day 0, peaked on day 2, and pseudonormalized by day 14. Lesion volumes peaked on day 2 and were temporally correlated with forelimb asymmetry and foot-fault scores. This study quantified the effects of perturbed CBF and CR on structural magnetic resonance imaging and behavioral readouts.
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Affiliation(s)
- Justin A Long
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Lora T Watts
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA.,Departments of Cellular and Structure Biology, University of Texas Health Science Center, San Antonio, Texas, USA.,Department of Neurology, University of Texas Health Science Center, Houston, Texas, USA
| | - Wei Li
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Qiang Shen
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Eric R Muir
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Shiliang Huang
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Robert C Boggs
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Abhinav Suri
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Timothy Q Duong
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA.,Department of Neurology, University of Texas Health Science Center, Houston, Texas, USA.,Department of Opthalmology, University of Texas Health Science Center, San Antonio, Texas, USA.,South Texas Veterans Health Care System, San Antonio, Texas, USA
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12
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Preservation of the blood brain barrier and cortical neuronal tissue by liraglutide, a long acting glucagon-like-1 analogue, after experimental traumatic brain injury. PLoS One 2015; 10:e0120074. [PMID: 25822252 PMCID: PMC4379006 DOI: 10.1371/journal.pone.0120074] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 02/02/2015] [Indexed: 01/04/2023] Open
Abstract
Cerebral edema is a common complication following moderate and severe traumatic brain injury (TBI), and a significant risk factor for development of neuronal death and deterioration of neurological outcome. To this date, medical approaches that effectively alleviate cerebral edema and neuronal death after TBI are not available. Glucagon-like peptide-1 (GLP-1) has anti-inflammatory properties on cerebral endothelium and exerts neuroprotective effects. Here, we investigated the effects of GLP-1 on secondary injury after moderate and severe TBI. Male Sprague Dawley rats were subjected either to TBI by Controlled Cortical Impact (CCI) or sham surgery. After surgery, vehicle or a GLP-1 analogue, Liraglutide, were administered subcutaneously twice daily for two days. Treatment with Liraglutide (200 μg/kg) significantly reduced cerebral edema in pericontusional regions and improved sensorimotor function 48 hours after CCI. The integrity of the blood-brain barrier was markedly preserved in Liraglutide treated animals, as determined by cerebral extravasation of Evans blue conjugated albumin. Furthermore, Liraglutide reduced cortical tissue loss, but did not affect tissue loss and delayed neuronal death in the thalamus on day 7 post injury. Together, our data suggest that the GLP-1 pathway might be a promising target in the therapy of cerebral edema and cortical neuronal injury after moderate and severe TBI.
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13
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Evaluation of cerebrovascular impedance and wave reflection in mouse by ultrasound. J Cereb Blood Flow Metab 2015; 35:521-6. [PMID: 25515209 PMCID: PMC4348395 DOI: 10.1038/jcbfm.2014.229] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 11/14/2014] [Accepted: 11/25/2014] [Indexed: 11/13/2022]
Abstract
Genetic and surgical mouse models are commonly used to study cerebrovascular disease, but their size makes invasive hemodynamic testing technically challenging. The purpose of this study was to demonstrate a noninvasive measurement of cerebrovascular impedance and wave reflection in mice using high-frequency ultrasound in the left common carotid artery (LCCA), and to examine whether microvascular changes associated with hypercapnia could be detected with such an approach. Ten mice (C57BL/6J) were studied using a high-frequency ultrasound system (40 MHz). Lumen area and blood flow waveforms were obtained from the LCCA and used to calculate pulse-wave velocity, input impedance, and reflection amplitude and transit time under both normocapnic and hypercapnic (5% CO2) ventilation. With hypercapnia, vascular resistance was observed to decrease by 87%±12%. Although the modulus of input impedance was unchanged with hypercapnia, a phase decrease indicative of increased total arterial compliance was observed at low harmonics together with an increased reflection coefficient in both the time (0.57±0.08 versus 0.68±0.08, P=0.04) and frequency domains (0.62±0.08 versus 0.73±0.06, P=0.02). Interestingly, the majority of LCCA blood flow was found to pass into the internal carotid artery (range=76% to 90%, N=3), suggesting that hemodynamic measurements in this vessel are a good metric for intracerebral reactivity in mouse.
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Bramlett HM, Dietrich WD. Long-Term Consequences of Traumatic Brain Injury: Current Status of Potential Mechanisms of Injury and Neurological Outcomes. J Neurotrauma 2014; 32:1834-48. [PMID: 25158206 DOI: 10.1089/neu.2014.3352] [Citation(s) in RCA: 296] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Traumatic brain injury (TBI) is a significant clinical problem with few therapeutic interventions successfully translated to the clinic. Increased importance on the progressive, long-term consequences of TBI have been emphasized, both in the experimental and clinical literature. Thus, there is a need for a better understanding of the chronic consequences of TBI, with the ultimate goal of developing novel therapeutic interventions to treat the devastating consequences of brain injury. In models of mild, moderate, and severe TBI, histopathological and behavioral studies have emphasized the progressive nature of the initial traumatic insult and the involvement of multiple pathophysiological mechanisms, including sustained injury cascades leading to prolonged motor and cognitive deficits. Recently, the increased incidence in age-dependent neurodegenerative diseases in this patient population has also been emphasized. Pathomechanisms felt to be active in the acute and long-term consequences of TBI include excitotoxicity, apoptosis, inflammatory events, seizures, demyelination, white matter pathology, as well as decreased neurogenesis. The current article will review many of these pathophysiological mechanisms that may be important targets for limiting the chronic consequences of TBI.
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Affiliation(s)
- Helen M Bramlett
- The Miami Project to Cure Paralysis/Department of Neurological Surgery, University of Miami Miller School of Medicine , Miami, Florida
| | - W Dalton Dietrich
- The Miami Project to Cure Paralysis/Department of Neurological Surgery, University of Miami Miller School of Medicine , Miami, Florida
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15
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Tress EE, Clark RSB, Foley LM, Alexander H, Hickey RW, Drabek T, Kochanek PM, Manole MD. Blood brain barrier is impermeable to solutes and permeable to water after experimental pediatric cardiac arrest. Neurosci Lett 2014; 578:17-21. [PMID: 24937271 DOI: 10.1016/j.neulet.2014.06.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 05/20/2014] [Accepted: 06/07/2014] [Indexed: 01/04/2023]
Abstract
Pediatric asphyxial cardiac arrest (CA) results in unfavorable neurological outcome in most survivors. Development of neuroprotective therapies is contingent upon understanding the permeability of intravenously delivered medications through the blood brain barrier (BBB). In a model of pediatric CA we sought to characterize BBB permeability to small and large molecular weight substances. Additionally, we measured the percent brain water after CA. Asphyxia of 9 min was induced in 16-18 day-old rats. The rats were resuscitated and the BBB permeability to small (sodium fluorescein and gadoteridol) and large (immunoglobulin G, IgG) molecules was assessed at 1, 4, and 24 h after asphyxial CA or sham surgery. Percent brain water was measured post-CA and in shams using wet-to-dry brain weight. Fluorescence, gadoteridol uptake, or IgG staining at 1, 4h and over the entire 24 h post-CA did not differ from shams, suggesting absence of BBB permeability to these solutes. Cerebral water content was increased at 3h post-CA vs. sham. In conclusion, after 9 min of asphyxial CA there is no BBB permeability over 24h to conventional small or large molecule tracers despite the fact that cerebral water content is increased early post-CA indicating the development of brain edema. Evaluation of novel therapies targeting neuronal death after pediatric CA should include their capacity to cross the BBB.
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Affiliation(s)
- Erika E Tress
- University of Pittsburgh, Department of Pediatrics, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
| | - Robert S B Clark
- University of Pittsburgh, Department of Pediatrics, 4401 Penn Avenue, Pittsburgh, PA 15224, USA; University of Pittsburgh, Critical Care Medicine, 3434 Fifth Avenue, Pittsburgh, PA 15260, USA; University of Pittsburgh, Safar Center for Resuscitation Research, 3434 Fifth Avenue, Pittsburgh, PA 15260, USA.
| | - Lesley M Foley
- Carnegie Mellon University, NMR Center for Biomedical Research, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
| | - Henry Alexander
- University of Pittsburgh, Critical Care Medicine, 3434 Fifth Avenue, Pittsburgh, PA 15260, USA; University of Pittsburgh, Safar Center for Resuscitation Research, 3434 Fifth Avenue, Pittsburgh, PA 15260, USA.
| | - Robert W Hickey
- University of Pittsburgh, Department of Pediatrics, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
| | - Tomas Drabek
- University of Pittsburgh, Safar Center for Resuscitation Research, 3434 Fifth Avenue, Pittsburgh, PA 15260, USA; University of Pittsburgh Department of Anesthesiology, 3434 Fifth Avenue, Pittsburgh, PA 15260, USA.
| | - Patrick M Kochanek
- University of Pittsburgh, Department of Pediatrics, 4401 Penn Avenue, Pittsburgh, PA 15224, USA; University of Pittsburgh, Critical Care Medicine, 3434 Fifth Avenue, Pittsburgh, PA 15260, USA; University of Pittsburgh, Safar Center for Resuscitation Research, 3434 Fifth Avenue, Pittsburgh, PA 15260, USA.
| | - Mioara D Manole
- University of Pittsburgh, Department of Pediatrics, 4401 Penn Avenue, Pittsburgh, PA 15224, USA; University of Pittsburgh, Safar Center for Resuscitation Research, 3434 Fifth Avenue, Pittsburgh, PA 15260, USA.
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16
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Age dependence of hemodynamic response characteristics in human functional magnetic resonance imaging. Neurobiol Aging 2013; 34:1469-85. [DOI: 10.1016/j.neurobiolaging.2012.11.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2012] [Revised: 10/01/2012] [Accepted: 11/02/2012] [Indexed: 01/13/2023]
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Abstract
PURPOSE OF REVIEW Traumatic brain injury (TBI) is a leading cause of death and long-term cognitive and behavioral dysfunction in children and young adults, yet effective treatments are lacking, in part because critical aspects of TBI neurobiology and natural history are not understood. We review recent advances in neuroimaging and discuss how they are helping to address these fundamental gaps. RECENT FINDINGS Novel imaging methods provide detailed information on how TBI affects anatomical integrity (diffusion tensor imaging; voxel-based morphometry; susceptibility-weighted imaging, magnetization transfer imaging), metabolic activity (magnetic resonance spectroscopy), perfusion (positron emission tomography, perfusion computed tomography, perfusion magnetic resonance), and patterns of functional activation (functional magnetic resonance imaging). Individually and collectively, these methods can significantly enhance TBI diagnosis and outcome prediction. SUMMARY Refinements in neuroimaging offer a window into the complex neuroanatomical and neurophysiological disturbances induced by TBI. Research is needed to understand how these alterations evolve with time and in response to therapeutic interventions.
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Mytar J, Kibler KK, Easley RB, Smielewski P, Czosnyka M, Andropoulos DB, Brady KM. Static Autoregulation Is Intact Early After Severe Unilateral Brain Injury in a Neonatal Swine Model. Neurosurgery 2012; 71:138-45. [DOI: 10.1227/neu.0b013e318251795a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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19
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Harris NG, Mironova YA, Chen SF, Richards HK, Pickard JD. Preventing flow-metabolism uncoupling acutely reduces axonal injury after traumatic brain injury. J Neurotrauma 2012; 29:1469-82. [PMID: 22321027 PMCID: PMC3335110 DOI: 10.1089/neu.2011.2161] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have previously presented evidence that the development of secondary traumatic axonal injury is related to the degree of local cerebral blood flow (LCBF) and flow-metabolism uncoupling. We have now tested the hypothesis that augmenting LCBF in the acute stages after brain injury prevents further axonal injury. Data were acquired from rats with or without acetazolamide (ACZ) that was administered immediately following controlled cortical impact injury to increase cortical LCBF. Local cerebral metabolic rate for glucose (LCMRglc) and LCBF measurements were obtained 3 h post-trauma in the same rat via ¹⁸F-fluorodeoxyglucose and ¹⁴C-iodoantipyrine co-registered autoradiographic images, and compared to the density of damaged axonal profiles in adjacent sections, and in additional groups at 24 h used to assess different populations of injured axons stereologically. ACZ treatment significantly and globally elevated LCBF twofold above untreated-injured rats at 3 h (p<0.05), but did not significantly affect LCMRglc. As a result, ipsilateral LCMRglc:LCBF ratios were reduced by twofold to sham-control levels, and the density of β-APP-stained axons at 24 h was significantly reduced in most brain regions compared to the untreated-injured group (p<0.01). Furthermore, early LCBF augmentation prevented the injury-associated increase in the number of stained axons from 3-24 h. Additional robust stereological analysis of impaired axonal transport and neurofilament compaction in the corpus callosum and cingulum underlying the injury core confirmed the amelioration of β-APP axon density, and showed a trend, but no significant effect, on RMO14-positive axons. These data underline the importance of maintaining flow-metabolism coupling immediately after injury in order to prevent further axonal injury, in at least one population of injured axons.
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Affiliation(s)
- Neil G Harris
- Department of Neurosurgery, David Geffen School of Medicine at UCLA, Box 957039, Los Angeles, CA 90095-7039, USA.
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20
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Archer T, Svensson K, Alricsson M. Physical exercise ameliorates deficits induced by traumatic brain injury. Acta Neurol Scand 2012; 125:293-302. [PMID: 22233115 DOI: 10.1111/j.1600-0404.2011.01638.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2011] [Indexed: 12/11/2022]
Abstract
The extent and depth of traumatic brain injury (TBI) remains a major determining factor together with the type of structural insult and its location, whether mild, moderate or severe, as well as the distribution and magnitude of inflammation and loss of cerebrovascular integrity, and the eventual efficacy of intervention. The influence of exercise intervention in TBI is multiple, ranging from anti-apoptotic effects to the augmentation of neuroplasticity. Physical exercise diminishes cerebral inflammation by elevating factors and agents involved in immunomodulatory function, and buttresses glial cell, cerebrovascular, and blood-brain barrier intactness. It provides unique non-pharmacologic intervention that incorporate different physical activity regimes, whether dynamic or static, endurance or resistance. Physical training regimes ought necessarily to be adapted to the specific demands of diagnosis, type and degree of injury and prognosis for individuals who have suffered TBI.
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Affiliation(s)
| | - K. Svensson
- School of Education; Psychology and Sport Science; Linnaeus University; Kalmar; Sweden
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21
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Hunter JV, Wilde EA, Tong KA, Holshouser BA. Emerging imaging tools for use with traumatic brain injury research. J Neurotrauma 2012; 29:654-71. [PMID: 21787167 PMCID: PMC3289847 DOI: 10.1089/neu.2011.1906] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
This article identifies emerging neuroimaging measures considered by the inter-agency Pediatric Traumatic Brain Injury (TBI) Neuroimaging Workgroup. This article attempts to address some of the potential uses of more advanced forms of imaging in TBI as well as highlight some of the current considerations and unresolved challenges of using them. We summarize emerging elements likely to gain more widespread use in the coming years, because of 1) their utility in diagnosis, prognosis, and understanding the natural course of degeneration or recovery following TBI, and potential for evaluating treatment strategies; 2) the ability of many centers to acquire these data with scanners and equipment that are readily available in existing clinical and research settings; and 3) advances in software that provide more automated, readily available, and cost-effective analysis methods for large scale data image analysis. These include multi-slice CT, volumetric MRI analysis, susceptibility-weighted imaging (SWI), diffusion tensor imaging (DTI), magnetization transfer imaging (MTI), arterial spin tag labeling (ASL), functional MRI (fMRI), including resting state and connectivity MRI, MR spectroscopy (MRS), and hyperpolarization scanning. However, we also include brief introductions to other specialized forms of advanced imaging that currently do require specialized equipment, for example, single photon emission computed tomography (SPECT), positron emission tomography (PET), encephalography (EEG), and magnetoencephalography (MEG)/magnetic source imaging (MSI). Finally, we identify some of the challenges that users of the emerging imaging CDEs may wish to consider, including quality control, performing multi-site and longitudinal imaging studies, and MR scanning in infants and children.
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Affiliation(s)
- Jill V Hunter
- Department of Pediatric Radiology, Texas Children's Hospital, Houston, Texas 77030, USA.
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22
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Dijkhuizen RM. Advances in MRI-Based Detection of Cerebrovascular Changes after Experimental Traumatic Brain Injury. Transl Stroke Res 2011; 2:524-32. [PMID: 22207884 PMCID: PMC3236292 DOI: 10.1007/s12975-011-0130-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 10/25/2011] [Accepted: 10/26/2011] [Indexed: 01/04/2023]
Abstract
Traumatic brain injury is a heterogeneous and multifaceted neurological disorder that involves diverse pathophysiological pathways and mechanisms. Thorough characterization and monitoring of the brain’s status after neurotrauma is therefore highly complicated. Magnetic resonance imaging (MRI) provides a versatile tool for in vivo spatiotemporal assessment of various aspects of central nervous system injury, such as edema formation, perfusion disturbances and structural tissue damage. Moreover, recent advances in MRI methods that make use of contrast agents have opened up additional opportunities for measurement of events at the level of the cerebrovasculature, such as blood–brain barrier permeability, leukocyte infiltration, cell adhesion molecule upregulation and vascular remodeling. It is becoming increasingly clear that these cerebrovascular alterations play a significant role in the progression of post-traumatic brain injury as well as in the process of post-traumatic brain repair. Application of advanced multiparametric MRI strategies in experimental, preclinical studies may significantly aid in the elucidation of pathomechanisms, monitoring of treatment effects, and identification of predictive markers after traumatic brain injury.
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Affiliation(s)
- Rick M. Dijkhuizen
- Biomedical MR Imaging and Spectroscopy Group, Image Sciences Institute, University Medical Center Utrecht, Building Nieuw Gildestein, Yalelaan 2, 3584 CM Utrecht, The Netherlands
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Hayward NMEA, Tuunanen PI, Immonen R, Ndode-Ekane XE, Pitkänen A, Gröhn O. Magnetic resonance imaging of regional hemodynamic and cerebrovascular recovery after lateral fluid-percussion brain injury in rats. J Cereb Blood Flow Metab 2011; 31:166-77. [PMID: 20485295 PMCID: PMC3049481 DOI: 10.1038/jcbfm.2010.67] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hemodynamic and cerebrovascular factors are crucially involved in secondary damage after traumatic brain injury (TBI). With magnetic resonance imaging, this study aimed to quantify regional cerebral blood flow (CBF) by arterial spin labeling and cerebral blood volume by using an intravascular contrast agent, during 14 days after lateral fluid-percussion injury (LFPI) in rats. Immunohistochemical analysis of vessel density was used to evaluate the contribution of vascular damage. Results show widespread ipsilateral and contralateral hypoperfusion, including both the cortex and the hippocampus bilaterally, as well as the ipsilateral thalamus. Hemodynamic unrest may partly be explained by an increase in blood vessel density over a period of 2 weeks in the ipsilateral hippocampus and perilesional cortex. Furthermore, three phases of perilesional alterations in CBF, progressing from hypoperfusion to normal and back to hypoperfusion within 2 weeks were shown for the first time in a rat TBI model. These three phases were similar to hemodynamic fluctuations reported in TBI patients. This makes it feasible to use LFPI in rats to study mechanisms behind hemodynamic changes and to explore novel therapeutic approaches for secondary brain damage after TBI.
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Affiliation(s)
- Nick Mark Edward Alexander Hayward
- Biomedical Imaging Unit, Department of Neurobiology, A I Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
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Ge Y, Patel MB, Chen Q, Grossman EJ, Zhang K, Miles L, Babb JS, Reaume J, Grossman RI. Assessment of thalamic perfusion in patients with mild traumatic brain injury by true FISP arterial spin labelling MR imaging at 3T. Brain Inj 2010; 23:666-74. [PMID: 19557570 DOI: 10.1080/02699050903014899] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE To assess cerebral blood flow (CBF) changes in patients with mild traumatic brain injury (MTBI) using an arterial spin labelling (ASL) perfusion MRI and to investigate the severity of neuropsychological functional impairment with respect to haemodynamic changes. MATERIALS AND METHODS Twenty-one patients with MTBI and 20 healthy controls were studied at 3T MR. The median time since the onset of brain injury in patients was 24.6 months. Both patients and controls underwent a traditional consensus battery of neurocognitive tests. ASL was performed using true fast imaging with steady state precession and a flow-sensitive alternating inversion recovery preparation. Regional CBF were measured in both deep and cortical gray matter as well as white matter at the level of basal ganglia. RESULTS The mean regional CBF was significantly lower in patients with MTBI (45.9 +/- 9.8 ml/100 g min(-1)) as compared to normal controls (57.1 +/- 8.1 ml/100 g min(-1); p = 0.002) in both sides of thalamus. The decrease of thalamic CBF was significantly correlated with several neurocognitive measures including processing and response speed, memory/learning, verbal fluency and executive function in patients. CONCLUSIONS Haemodynamic impairment can occur and persist in patients with MTBI, the extent of which is more severe in thalamic regions and correlate with neurocognitive dysfunction during the extended course of disease.
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Affiliation(s)
- Yulin Ge
- Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York 10016, USA.
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25
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Voigt C, Förschler A, Jaeger M, Meixensberger J, Küppers-Tiedt L, Schuhmann MU. Protective effect of hyperbaric oxygen therapy on experimental brain contusions. ACTA NEUROCHIRURGICA. SUPPLEMENT 2009; 102:441-5. [PMID: 19388363 DOI: 10.1007/978-3-211-85578-2_86] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2023]
Abstract
BACKGROUND We evaluated the effect of hyperbaric oxygen therapy (HBO) on experimental brain contusions in rats using magnetic resonance imaging (MRI). MATERIALS AND METHODS Ten Sprague-Dawley rats were investigated at 24 h and 72 h after controlled cortical impact injury. One hour after trauma, 5 rats were treated for 60 min with 100% oxygen at 2.5 absolute atmosphere (ATA), 5 were kept at normobaric room air. MRI was performed longitudinally at 24 h and 72 h after injury. Lesion volume was determined in T2 weighted MRI scans. Relative apparent diffusion coefficient (ADC) changes were calculated in comparison to the contralateral side. RESULTS Following HBO, T2 lesion volume was smaller at 24 h versus controls (63.1 +/- 16.5 mm3 vs. 87.4 +/- 13.8 mm3, p < 0.05), and decreased further at 72 h (46.8 +/- 17.8 mm3 vs. 92.5 +/- 13.1 mm3, p < 0.01). At 24 h, the mean relative ADC change in the lesion area decreased from + 26.8 +/- 2.3% in controls to + 2.3 +/- 12.2% in HBO animals (p < 0.01). At 72 h, the HBO effect on relative ADC values was less when compared to 24 h. DISCUSSION A 60-minute exposure to hyperbaric oxygen starting 1 h after impact injury significantly attenuated lesion growth and relative increase of ADC values within the contused area for up to 72 h. Thus, a "single-shot" HBO treatment seems to have long-lasting neuroprotective effects on the contused brain and its penumbra.
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Affiliation(s)
- Cornelia Voigt
- Department of Neurosurgery, University of Leipzig, 04103 Leipzig, Germany.
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26
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Kiefer C, Schroth G, Gralla J, Diehm N, Baumgartner I, Husmann M. A feasibility study on model-based evaluation of kidney perfusion measured by means of FAIR prepared true-FISP arterial spin labeling (ASL) on a 3-T MR scanner. Acad Radiol 2009; 16:79-87. [PMID: 19064215 DOI: 10.1016/j.acra.2008.04.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 04/14/2008] [Accepted: 04/24/2008] [Indexed: 11/30/2022]
Abstract
RATIONALE AND OBJECTIVES A feasibility study on measuring kidney perfusion by a contrast-free magnetic resonance (MR) imaging technique is presented. MATERIALS AND METHODS A flow-sensitive alternating inversion recovery (FAIR) prepared true fast imaging with steady-state precession (TrueFISP) arterial spin labeling sequence was used on a 3.0-T MR-scanner. The basis for quantification is a two-compartment exchange model proposed by Parkes that corrects for diverse assumptions in single-compartment standard models. RESULTS Eleven healthy volunteers (mean age, 42.3 years; range 24-55) were examined. The calculated mean renal blood flow values for the exchange model (109 +/- 5 [medulla] and 245 +/- 11 [cortex] ml/min - 100 g) are in good agreement with the literature. Most important, the two-compartment exchange model exhibits a stabilizing effect on the evaluation of perfusion values if the finite permeability of the vessel wall and the venous outflow (fast solution) are considered: the values for the one-compartment standard model were 93 +/- 18 (medulla) and 208 +/- 37 (cortex) ml/min - 100 g. CONCLUSION This improvement will increase the accuracy of contrast-free imaging of kidney perfusion in treatment renovascular disease.
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Affiliation(s)
- Claus Kiefer
- Department of Angiology, Institute for Diagnostic and Interventional Neuroradiology, University Hospital Berne and University of Berne, Berne, Switzerland.
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27
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Henninger N, Sicard KM, Li Z, Kulkarni P, Dützmann S, Urbanek C, Schwab S, Fisher M. Differential recovery of behavioral status and brain function assessed with functional magnetic resonance imaging after mild traumatic brain injury in the rat. Crit Care Med 2008; 35:2607-14. [PMID: 17828037 DOI: 10.1097/01.ccm.0000286395.79654.8d] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The relationship between cerebral integrity, recovery of brain function, and neurologic status after mild traumatic brain injury is incompletely characterized. DESIGN Prospective and randomized study in rodents. SETTING University laboratory. SUBJECTS Male Wistar rats (290-310 g). INTERVENTIONS In rats, quantitative diffusion weighted imaging (DWI), perfusion weighted imaging (PWI), T2-weighted imaging (T2WI), and functional magnetic resonance imaging (fMRI) were performed up to 21 days after weight-induced, closed-head, mild traumatic brain injury (MTBI, n = 6) or sham operation (n = 6). Pixel-by-pixel analysis and region of interest analysis were used to evaluate structural (apparent diffusion coefficient [ADC] and basal cerebral blood flow [bCBF]) and functional magnetic resonance signal changes within the brain, respectively. Quantitative fMRI signal changes were correlated with behavioral measures. MEASUREMENTS AND MAIN RESULTS Despite normal appearing DWI and T2WI findings following MTBI, persistent hypoperfusion developed that was not associated with cytotoxic edema. In contrast, the ADC was significantly increased by approximately 5% at 1 and 7 days post-MTBI. Post-MTBI fMRI responses to hypercapnia and forepaw stimulation were significantly impaired and showed a differential recovery rate between and within investigated region of interests. Significant dysfunction in forepaw placement test persisted up to day 1 and correlated significantly with fMRI signal changes in the primary somatosensory and motor cortices. CONCLUSIONS MTBI produced distinct changes on multimodal MRI and behavioral variables acutely and chronically. Following MTBI, fMRI and ADC-bCBF pixel-by-pixel analysis identified subtle structural and functional alterations in the brain that appeared completely normal on conventional DWI and T2WI after concussion injury. The former techniques may therefore provide great potential for understanding mild traumatic brain injury, identifying mechanisms underlying recovery, and investigating specific interventions to enhance functional outcome.
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Affiliation(s)
- Nils Henninger
- Department of Internal Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
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28
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Hillary FG, Biswal B. The influence of neuropathology on the FMRI signal: a measurement of brain or vein? Clin Neuropsychol 2007; 21:58-72. [PMID: 17366278 DOI: 10.1080/13854040601064542] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
There is a rapidly growing literature using fMRI technology to investigate the various forms of behavioral impairment associated with brain injury and disease. Given this, surprisingly little work has been conducted to examine the influence of neuropathophysiological processes on the fMRI signal. This paper reviews the literature examining baseline alteration in cerebrovascular parameters associated with normal aging, brain injury, and brain disease. In addition, findings from three cases of individuals with severe brain trauma will be presented to show the influence of brain trauma on baseline cerebrovascular parameters measured by fMRI. The methods used here can be implemented by other investigators to accurately isolate specific hemodynamic changes that can influence the BOLD fMRI signal.
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Affiliation(s)
- F G Hillary
- Psychology Department, Pennsylvania State University, State College, PA , USA.
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Shen Y, Kou Z, Kreipke CW, Petrov T, Hu J, Haacke EM. In vivo measurement of tissue damage, oxygen saturation changes and blood flow changes after experimental traumatic brain injury in rats using susceptibility weighted imaging. Magn Reson Imaging 2006; 25:219-27. [PMID: 17275617 DOI: 10.1016/j.mri.2006.09.018] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2006] [Accepted: 09/15/2006] [Indexed: 12/31/2022]
Abstract
Traumatic brain injury (TBI) is a prevalent disease, and many TBI patients experience disturbed cerebral blood flow (CBF) after injury. Moreover, TBI is difficult to quantify with conventional imaging modalities. In this paper, we utilized susceptibility weighted imaging (SWI) as a means to monitor functional blood oxygenation changes and to quantify CBF changes in animals after trauma. In this study using six rats, brain trauma was induced by a weight drop model and the brain was scanned over four time points: pre trauma, and 4 h, 24 h and 48 h post trauma. Five rats survived and one died after trauma. A blood phase analysis using filtered SWI phase images suggested that three rats recovered after 48 h and two rats deteriorated. SWI also suggested that CBF decreased by up to 26%. The CBF change is in agreement with the results of arterial spin labeling methods conducted in this study and with previously published results. Furthermore, SWI revealed an enlargement of the major venous vasculature in deep brain structures, in accordance with the location of diffuse axonal injury. Compared with the traditional, invasive, clinical monitoring of cerebral vascular damage and reduction in blood flow, this method offers a novel, safe and noninvasive approach to quantify changes in oxygen saturation and CBF and to visualize structural changes in blood vasculature after TBI.
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Affiliation(s)
- Yimin Shen
- Department of Radiology, Wayne State University, Detroit, MI 48201, USA
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Kochanek PM, Hendrich KS, Jackson EK, Wisniewski SR, Melick JA, Shore PM, Janesko KL, Zacharia L, Ho C. Characterization of the effects of adenosine receptor agonists on cerebral blood flow in uninjured and traumatically injured rat brain using continuous arterial spin-labeled magnetic resonance imaging. J Cereb Blood Flow Metab 2005; 25:1596-612. [PMID: 15931163 DOI: 10.1038/sj.jcbfm.9600154] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Hypoperfusion after traumatic brain injury may exacerbate damage. Adenosine, a vasodilator, regulates cerebral blood flow (CBF). Treatment with adenosine receptor agonists has shown benefit in experimental CNS trauma; however, their effects on CBF after injury remain undefined. We used magnetic resonance imaging to assess CBF in uninjured rats both early and at 24 h after intrahippocampal administration of either the nonselective adenosine receptor agonist 2-chloroadenosine (2-CA, 12 nmol) or the A(2A)-receptor agonist 2-p-(2-carboxyethyl)-phenethylamino-5'-N-ethylcarbox-amidoadenosine (CGS 21680, 6 nmol). We also assessed the effects of these agents on cerebral metabolic rate for glucose (CMRglu). We then assessed the effect of 2-CA on CBF at 3.5 to 5 h after controlled cortical impact (CCI). Injection of 2-CA into uninjured rat brain produced marked increases in CBF in ipsilateral hippocampus and cortex versus vehicle (P<0.05); CBF increases persisted even at 24 h. Measurement of hippocampal levels of 2-CA showed persistent increases to 24 h. CGS 21680 produced even more marked global increases in CBF than seen with 2-CA (2-6-fold versus vehicle, P<0.05 in 10/12 regions of interest (ROIs)). Neither agonist altered CMRglu versus vehicle. After CCI, 2-CA increased CBF in ipsilateral hippocampal and hemispheric ROIs (P<0.05 versus vehicle), but the response was attenuated at severe injury levels. We report marked increases in CBF after injection of adenosine receptor agonists into uninjured rat brain despite unaltered CMRglu. 2-Chloroadenosine produced enduring increases in CBF in uninjured brain and attenuated posttraumatic hypoperfusion. Future studies of adenosine-related therapies in CNS injury should address the role of CBF.
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Affiliation(s)
- Patrick M Kochanek
- Safar Center for Resuscitation Research, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
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Moffat BA, Chenevert TL, Hall DE, Rehemtulla A, Ross BD. Continuous arterial spin labeling using a train of adiabatic inversion pulses. J Magn Reson Imaging 2005; 21:290-6. [PMID: 15723380 DOI: 10.1002/jmri.20268] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To develop a simple and robust magnetic resonance imaging (MRI) pulse sequence for the quantitative measurement of blood flow in the brain and cerebral tumors that has practical implementation advantages over currently used continuous arterial spin labeling (CASL) schemes. MATERIALS AND METHODS Presented here is a single-coil protocol that uses a train of hyperbolic secant inversion pulses to produce continuous arterial spin inversion for perfusion weighting of fast spin echo images. Flow maps of normal rat brains and those containing a 9L gliosarcoma orthotopic tumor model conditions were acquired with and without carbogen. RESULTS The perfusion-weighted images have reduced magnetization transfer signal degradation as compared to the traditional single-coil CASL while avoiding the use of a more complex two-coil CASL technique. Blood flow measurements in tumor and normal brain tissue were consistent with those previously reported by other CASL techniques. Contralateral and normal brain showed increased blood flow with carbogen breathing, while tumor tissue lacked the same CO(2) reactivity. CONCLUSION This variation of the CASL technique is a quantitative, robust, and practical single-coil method for measuring blood flow. This CASL method does not require specialized radiofrequency coils or amplifiers that are not routinely used for anatomic imaging of the brain, therefore allowing these flow measurements to be easily incorporated into traditional rodent neuroimaging protocols.
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Affiliation(s)
- Bradford A Moffat
- Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA
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Chen SF, Richards HK, Smielewski P, Johnström P, Salvador R, Pickard JD, Harris NG. Relationship between flow-metabolism uncoupling and evolving axonal injury after experimental traumatic brain injury. J Cereb Blood Flow Metab 2004; 24:1025-36. [PMID: 15356423 DOI: 10.1097/01.wcb.0000129415.34520.47] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Blood flow-metabolism uncoupling is a well-documented phenomenon after traumatic brain injury, but little is known about the direct consequences for white matter. The aim of this study was to quantitatively assess the topographic interrelationship between local cerebral blood flow (LCBF) and glucose metabolism (LCMRglc) after controlled cortical impact injury and to determine the degree of correspondence with the evolving axonal injury. LCMRglc and LCBF measurements were obtained at 3 hours in the same rat from 18F-fluorodeoxyglucose and 14C-iodoantipyrine coregistered autoradiographic images, and compared to the density of damaged axonal profiles in adjacent sections and in an additional group at 24 hours using beta-amyloid precursor protein (beta-APP) immunohistochemistry. LCBF was significantly reduced over the ipsilateral hemisphere by 48 +/- 15% compared with sham-controls, whereas LCMRglc was unaffected, apart from foci of elevated LCMRglc in the contusion margin. Flow-metabolism was uncoupled, indicated by a significant 2-fold elevation in the LCMRglc/LCBF ratio within most ipsilateral structures. There was a significant increase in beta-APP-stained axons from 3 to 24 hours, which was negatively correlated with LCBF and positively correlated with the LCMRglc/LCBF ratio at 3 hours in the cingulum and corpus callosum. Our study indicates a possible dependence of axonal outcome on flow-metabolism in the acute injury stage.
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Affiliation(s)
- Szu-Fu Chen
- Academic Neurosurgery, Center for Brain Repair, University of Cambridge, Robinson Way, UK
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Abstract
Arterial spin labeling is a magnetic resonance method for the measurement of cerebral blood flow. In its simplest form, the perfusion contrast in the images gathered by this technique comes from the subtraction of two successively acquired images: one with, and one without, proximal labeling of arterial water spins after a small delay time. Over the last decade, the method has moved from the experimental laboratory to the clinical environment. Furthermore, numerous improvements, ranging from new pulse sequence implementations to extensive theoretical studies, have broadened its reach and extended its potential applications. In this review, the multiple facets of this powerful yet difficult technique are discussed. Different implementations are compared, the theoretical background is summarized, and potential applications of various implementations in research as well as in the daily clinical routine are proposed. Finally, a summary of the new developments and emerging techniques in this field is provided.
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Affiliation(s)
- Xavier Golay
- Department of Neuroradiology, National Neuroscience Institute, Singapore.
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Abstract
This review gives an overview of the application of magnetic resonance imaging (MRI) in experimental models of brain disorders. MRI is a noninvasive and versatile imaging modality that allows longitudinal and three-dimensional assessment of tissue morphology, metabolism, physiology, and function. MRI can be sensitized to proton density, T1, T2, susceptibility contrast, magnetization transfer, diffusion, perfusion, and flow. The combination of different MRI approaches (e.g., diffusion-weighted MRI, perfusion MRI, functional MRI, cell-specific MRI, and molecular MRI) allows in vivo multiparametric assessment of the pathophysiology, recovery mechanisms, and treatment strategies in experimental models of stroke, brain tumors, multiple sclerosis, neurodegenerative diseases, traumatic brain injury, epilepsy, and other brain disorders. This report reviews established MRI methods as well as promising developments in MRI research that have advanced and continue to improve our understanding of neurologic diseases and that are believed to contribute to the development of recovery improving strategies.
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Affiliation(s)
- Rick M Dijkhuizen
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands.
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Ueda Y, Wei EP, Kontos HA, Suehiro E, Povlishock JT. Effects of delayed, prolonged hypothermia on the pial vascular response after traumatic brain injury in rats. J Neurosurg 2003; 99:899-906. [PMID: 14609171 DOI: 10.3171/jns.2003.99.5.0899] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object. In the experimental setting, hypothermia has been demonstrated to attenuate the damaging consequences of stroke and traumatic brain injury (TBI). Laboratory studies of TBI have focused primarily on the use of early hypothermic intervention, with little consideration of the potential efficacy of more delayed but prolonged hypothermia, which would constitute a more clinically relevant approach. In this investigation, the authors evaluated whether delayed, prolonged hypothermia after TBI protected the cerebral microcirculation.
Methods. Male Sprague—Dawley rats were equipped with cranial windows for direct visualization of the pial arterial circulation and then subjected to impact-acceleration brain injury. The rats were randomly divided into four experimental groups: Group 1 consisted of normothermic animals; in Group 2 the rats received a 1-hour period of hypothermia (32°C) 30 minutes posttrauma, followed by slow rewarming (32–37°C/90 minutes); and in Groups 3 and 4 the rats received a more delayed induction (at 1 hour postinjury) of either 1 hour (Group 3) or 2 hours (Group 4) of hypothermia, followed by the slow rewarming. The pial arteriolar responses to acetylcholine (ACh) or hypercapnia were measured until up to 6 hours postinjury. With this approach the authors found that the normothermic group demonstrated severely impaired vasoreactivity in terms of ACh-dependent dilation and CO2 reactivity in comparison to baseline values (p < 0.001). In contrast, hypothermia of short duration that was initiated early (30 minutes postinjury) conferred significant cerebrovascular protection (p < 0.001), yet this protection was reduced when the onset of this 1-hour hypothermic period was postponed to 1 hour postinjury. Nevertheless, reduced protection could be significantly improved (p < 0.001) with prolongation of the hypothermic period to 2 hours.
Conclusions. The results of this study show that early as well as delayed but prolonged hypothermia attenuate the impaired vascular responsiveness seen after TBI, indicating the potential clinical usefulness of this treatment.
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Affiliation(s)
- Yuji Ueda
- Department of Anatomy, Medical College of Virginia, Campus of Virginia Commonwealth University, Richmond, Virginia 23298-0709, USA
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36
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Krep H, Böttiger BW, Bock C, Kerskens CM, Radermacher B, Fischer M, Hoehn M, Hossmann KA. Time course of circulatory and metabolic recovery of cat brain after cardiac arrest assessed by perfusion- and diffusion-weighted imaging and MR-spectroscopy. Resuscitation 2003; 58:337-48. [PMID: 12969612 DOI: 10.1016/s0300-9572(03)00151-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Brain recovery after cardiac arrest (CA) was assessed in cats using arterial spin tagging perfusion-weighted imaging (PWI), diffusion-weighted imaging (DWI), and 1H-spectroscopy (1H-MRS). Cerebral reperfusion and metabolic recovery was monitored in the cortex and in basal ganglia for 6 h after cardiopulmonary resuscitation (CPR). Furthermore, the effects of an hypertonic/hyperoncotic solution (7.5% NaCl/6% hydroxyl ethyl starch, HES) and a tissue-type plasminogen activator (TPA), applied during CPR, were assessed on brain recovery. CA and CPR were carried out in the MR scanner by remote control. CA for 15-20 min was induced by electrical fibrillation of the heart, followed by CPR using a pneumatic vest. PWI after successful CPR revealed initial cerebral hyperperfusion followed by delayed hypoperfusion. Initial cerebral recirculation was improved after osmotic treatment. Osmotic and thrombolytic therapy were ineffective in ameliorating delayed hypoperfusion. Calculation of the apparent diffusion coefficient (ADC) from DWI demonstrated complete recovery of ion and water homeostasis in all animals. 1H-MRS measurements of lactate suggested an extended preservation of post-ischaemic anaerobic metabolism after TPA treatment. The combination of noninvasive MR techniques is a powerful tool for the evaluation of therapeutical strategies on circulatory and metabolic cerebral recovery after experimental cerebral ischaemia.
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Affiliation(s)
- Henning Krep
- Department of Anesthesia and Intensive Care Medicine, University Hospital Bonn, Bonn, Germany.
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37
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DeWitt DS, Prough DS. Traumatic Cerebral Vascular Injury: The Effects of Concussive Brain Injury on the Cerebral Vasculature. J Neurotrauma 2003; 20:795-825. [PMID: 14577860 DOI: 10.1089/089771503322385755] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In terms of human suffering, medical expenses, and lost productivity, head injury is one of the major health care problems in the United States, and inadequate cerebral blood flow is an important contributor to mortality and morbidity after traumatic brain injury. Despite the importance of cerebral vascular dysfunction in the pathophysiology of traumatic brain injury, the effects of trauma on the cerebral circulation have been less well studied than the effects of trauma on the brain. Recent research has led to a better understanding of the physiologic, cellular, and molecular components and causes of traumatic cerebral vascular injury. A more thorough understanding of the direct and indirect effects of trauma on the cerebral vasculature will lead to improvements in current treatments of brain trauma as well as to the development of novel and, hopefully, more effective therapeutic strategies.
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Affiliation(s)
- Douglas S DeWitt
- Charles R. Allen Research Laboratories, Department of Anesthesiology, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0830, USA.
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Thomale UW, Schaser K, Kroppenstedt SN, Unterberg AW, Stover JF. Cortical hypoperfusion precedes hyperperfusion following controlled cortical impact injury. ACTA NEUROCHIRURGICA. SUPPLEMENT 2003; 81:229-31. [PMID: 12168311 DOI: 10.1007/978-3-7091-6738-0_59] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
Impaired cerebral perfusion contributes to tissue damage following traumatic brain injury. In this longitudinal study persistence of reduced cortical perfusion employing laser doppler flowmetry was investigated following controlled cortical impact injury (CCII). Before, 30 minutes, 6, 24, and 48 hours after CCII, perfusion in pericontusional cortex was determined by moving a laser doppler probe in 50 x 0.2 mm steps over the traumatized hemisphere in 5 rats. Arterial blood gases and mean arterial blood pressure were monitored. Mean arterial blood pressure and arterial blood gases remained stable during the entire experiments. At 30 minutes and 6 hours following CCII, cortical perfusion was significantly diminished by 24% and 43% (p < 0.05), respectively compared to pre-trauma levels. At 24 and 48 hours after CCII, pericontusional blood flow was significantly increased by 64% and 123%. Cortical hypoperfusion found within the early phase following trauma is reversible and precedes a long lasting phase of hyperperfusion. Changes in tissue mediators (endothelin, acidosis, NO) could account for these findings.
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Affiliation(s)
- U W Thomale
- Department of Neurosurgery, Charité, Virchow Medical Center, Humboldt-University of Berlin, Germany
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39
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Abstract
The main aim of this review is to describe some of the many animal models that have proved to be valuable from a neuroimaging perspective. This paper complements other articles in this volume, with a focus on animal models of the pathology of human brain disorders for investigations with modern non-invasive neuroimaging techniques. The use of animal model systems forms a fundamental part of neuroscience research efforts to improve the prevention, diagnosis, understanding and treatment of neurological conditions. Without such models it would be impossible to investigate such topics as the underlying mechanisms of neuronal cell damage and death, or to screen compounds for possible anticonvulsant properties. The adequacy of any one particular model depends on the suitability of information gained during experimental conditions. It is important, therefore, to understand the various types of animal model available and choose an appropriate model for the research question.
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Affiliation(s)
- Mark F Lythgoe
- RCS Unit of Biophysics, Institute of Child Health, University College London, UK
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40
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Zhang F, Sprague SM, Farrokhi F, Henry MN, Son MG, Vollmer DG. Reversal of attenuation of cerebrovascular reactivity to hypercapnia by a nitric oxide donor after controlled cortical impact in a rat model of traumatic brain injury. J Neurosurg 2002; 97:963-9. [PMID: 12405388 DOI: 10.3171/jns.2002.97.4.0963] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Traumatic brain injury (TBI) attenuates the cerebral vasodilation to hypercapnia. Cortical spreading depression (CSD) also transiently reduces hypercapnic vasodilation. The authors sought to determine whether the CSD elicited by a controlled cortical impact (CCI) injury masks the true effect of TBI on hypercapnic vasodilation, and whether a nitric oxide (NO) donor can reverse the attenuation of hypercapnic vasodilation following CCI. METHODS Anesthetized rats underwent moderate CCI. Cerebral blood flow was monitored with laser Doppler flowmetry and the response to hypercapnia was determined for injured and sham-injured animals. The effect of the NO donor, S-nitroso-N-acetylpenicillamine (SNAP), on this response was also assessed. At an uninjured cortical site ipsilateral to the CCI, a single wave of CSD was recorded and the CO2 response at this location was significantly attenuated for up to 30 minutes (seven rats, p < 0.05). At the injured cortex, hypercapnic vasodilation continued to be attenuated for 7 hours. The cerebral vasodilation to CO2 was 37 +/- 5% in injured rats (six) compared with 84 +/- 10% in the sham-injured group (five rats, p < 0.05). After 30 minutes of topical superfusion with SNAP, hypercapnic vasodilation was restored to 74 +/- 7% (nine rats, p > 0.1 compared with that in the sham-injured group). In contrast, papaverine, an NO-independent vasodilator, failed to reverse the attenuation of the CO2 response to CCI. CONCLUSIONS The authors conclude that CSD elicited by CCI can mask the true effect of TBI on hypercapnic vasodilation for at least 30 minutes. Exogenous NO, but not papaverine, can reverse the attenuation of cerebrovascular reactivity to CO2 caused by TBI. This result supports the hypothesis that NO production is reduced after TBI and that the NO donor has a potential beneficial role in the clinical management of head injury.
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Affiliation(s)
- Fangyi Zhang
- Department of Surgery, University of Texas Health Science Center, San Antonio 78229-3900, USA.
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41
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Kochanek PM, Hendrich KS, Dixon CE, Schiding JK, Williams DS, Ho C. Cerebral blood flow at one year after controlled cortical impact in rats: assessment by magnetic resonance imaging. J Neurotrauma 2002; 19:1029-37. [PMID: 12482116 DOI: 10.1089/089771502760341947] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Progressive tissue loss and delayed cognitive deficits are seen in rats during the initial year after experimental traumatic brain injury (TBI). As much as 10% of parenchymal volume is lost even in the contralateral hemisphere by 1 year after controlled cortical impact (CCI) in rats. Progressive declines in cerebral blood flow (CBF) are also associated with advanced age and neurodegenerative diseases. Surprisingly, the long-term effects of TBI on CBF remain undefined. CBF was quantified by continuous arterial spin-labeled magnetic resonance imaging (MRI) and measurements of spin-lattice relaxation time in a slice through the plane of injury at 1 year after experimental TBI produced by CCI (n = 4) or sham surgery (n = 4) in rats. CBF was quantified in six regions of interest (ROIs) that were anatomically identified on the control images in each hemisphere and included a medial cortical segment (contusion-enriched, beneath the impact site, on the ipsilateral side) cortex, hippocampus, thalamus, amygdala/pyriform cortex, and hemisphere. At 1 year after injury, CBF was dramatically (96%) reduced in structures within the large cystic lesion that was seen in three of four rats and variably included cortex and hippocampus. Overall, there was an 80% reduction in CBF in the ipsilateral medial cortical segment comparing CCI and sham groups. Similarly, 52% and 67% reductions were seen in CBF in the cortical and hippocampal ROIs ipsilateral to impact (CCI vs. sham), respectively. These are regions both with marked CBF disturbances early after injury and that ultimately suffer considerable tissue loss over the 1-year interval. However, at 1 year after CCI, CBF was not different from sham in other ROIs, including ipsilateral thalamus, or either contralateral hippocampus or hemisphere. We conclude that, at 1 year after CCI, CBF is reduced in anatomic structures at or near the impact site, including injured cortex and hippocampus, and this translates into a reduction in hemispheric CBF. However, despite both significant occult tissue loss ipsilateral and contralateral to the injury and delayed cognitive deficits, widespread reductions in CBF are not observed. This suggests the possibility of remodeling or repackaging of the brain that preserves CBF outside of the cystic lesion.
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Affiliation(s)
- Patrick M Kochanek
- Department of Critical Care Medicine and Anesthesiology, Center for Resuscitation Research, Pittsburgh, Pennsylvania 15260, USA.
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42
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Thomale UW, Kroppenstedt SN, Beyer TF, Schaser KD, Unterberg AW, Stover JF. Temporal profile of cortical perfusion and microcirculation after controlled cortical impact injury in rats. J Neurotrauma 2002; 19:403-13. [PMID: 11990347 DOI: 10.1089/08977150252932361] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Impaired cerebral perfusion contributes to evolving posttraumatic tissue damage. Spontaneous reversibility of reduced perfusion within the first days after injury could make a persisting impact on secondary tissue damage less likely and needs to be considered for possible therapeutic approaches. The present study was designed to characterize the temporal profile and impact of trauma severity on cortical perfusion and microcirculation during the first 48 h after controlled cortical impact injury (CCI). In 10 rats, pericontusional cortical perfusion and microcirculation using laser Doppler flowmetry (LDF) and orthogonal polarization spectral (OPS) imaging were assessed before, and at 4, 24, and 48 h after CCI. Influence of trauma severity was studied by varying the penetration depth of the impactor rod (0.5 vs. 1 mm), thereby inducing a less and a more severe contusion. Mean arterial blood pressure (MABP), arterial blood gases, and blood glucose were monitored. With unchanged MABP and paCO2, cortical perfusion and microcirculation were significantly impaired during the first 48 h following CCI. Hypoperfusion observed at 4 h related to vasoconstriction and microcirculatory stasis preceded a long-lasting phase of hyperperfusion at 24 and 48 h reflected by vasodilation and increased flow velocity in arterioles and venules. Hyperperfusion was mostly pronounced in rats with a less severe contusion. Following CCI, trauma severity markedly influences changes in pericontusional cortical perfusion and microcirculation. Overall, pericontusional cortical hypoperfusion observed within the early phase preceded a long lasting phase of hyperperfusion up to 48 h after CCI.
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Affiliation(s)
- Ulrich-Wilhelm Thomale
- Department of Neurosurgery, Charité, Virchow Medical Center, Humboldt-University of Berlin, Germany.
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Schuhmann MU, Stiller D, Thomas S, Brinker T, Samii M. 1H-MR spectroscopic monitoring of posttraumatic metabolism following controlled cortical impact injury: pilot study. ACTA NEUROCHIRURGICA. SUPPLEMENT 2001; 76:3-7. [PMID: 11450030 DOI: 10.1007/978-3-7091-6346-7_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Proton magnetic resonance spectroscopy (1H-MRS) has been increasingly utilised in experimental traumatic brain injury for characterisation of posttraumatic metabolic dysfunction. Following human brain injury pathological findings correlated with outcome measures. Combined with conventional T2-weighted MR imaging MRS is a sensitive tool to evaluate metabolic changes in brain tissue following trauma. Studies have been restricted so far to diffuse axonal injury models and fluid percussion injury. Using a high resolution scanner at 4.7 T, MRI combined with 1H-MRS was applied in a pilot study to the controlled cortical impact injury model of experimental brain contusion (CCII). Eight Sprague-Dawley rats were investigated, of which two served as controls. Four animals were injured 24 h after craniotomy, two investigated at 72 h post craniotomy. MRS/MRI indicated a transient brain oedema development and metabolic changes induced by the craniotomy itself. Following CCII MRI demonstrated that the area of contusion as well as the surrounding brain oedema increased twofold in size within 24 h (p < 0.05). MRS showed an immediate increase of N-acetylaspartate (NAA) and glutamate ipsilateral to the contusion and a drop of NAA on the contralateral side. MRS/MRI investigations in the CCII model demonstrated a potential to further elucidate the pathophysiology following traumatic brain contusion.
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Affiliation(s)
- M U Schuhmann
- Department of Neurosurgery, Medical School Hannover, Germany
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Cheung C, Culver JP, Takahashi K, Greenberg JH, Yodh AG. In vivo cerebrovascular measurement combining diffuse near-infrared absorption and correlation spectroscopies. Phys Med Biol 2001; 46:2053-65. [PMID: 11512610 DOI: 10.1088/0031-9155/46/8/302] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We combine two near-infrared diffuse optical techniques to study variations of blood flow, haemoglobin concentration, and blood oxygen saturation in the functioning rat brain. Diffuse correlation spectroscopy (or flowmetry) monitors changes in the cerebral blood flow, without the use of the principles of tracer clearance, by measuring the optical phase-shifts caused by moving blood cells. Near-infrared absorption spectroscopy concurrently measures tissue absorption at two wavelengths to determine haemoglobin concentration and blood oxygen saturation in this same tissue volume. This optical probe is non-invasive and was employed through the intact skull. The utility of the technique is demonstrated in vivo by measuring the temporal changes in the regional vascular dynamics of rat brain during hypercapnia. Temporal and spatial variations of cerebral blood flow, haemoglobin concentration and blood oxygen saturation during hypercapnia are compared with other measurements in the literature, and a quantitative analysis demonstrating the self-consistency of our combined observations of vascular response is presented.
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Affiliation(s)
- C Cheung
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia 19104, USA
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45
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Hauerberg J, Ma X, Bay-Hansen R, Pedersen DB, Rochat P, Juhler M. Effects of alterations in arterial CO2 tension on cerebral blood flow during acute intracranial hypertension in rats. J Neurosurg Anesthesiol 2001; 13:213-21. [PMID: 11426095 DOI: 10.1097/00008506-200107000-00006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cerebrovascular reactivity to CO2 in clinical and experimental studies has been found to be impaired during increased intracranial pressure (ICP). However, from previous study results it has not been possible to estimate whether the impairment was caused by elevated ICP, or caused by decreased cerebral perfusion pressure (CPP). The current study was carried out in a group of unmanipulated control rats and in six investigation groups of six rats each: two groups with elevated ICP (30 and 50 mm Hg) and spontaneous arterial blood pressure (MABP), two groups with spontaneous ICP and arterial hypotension (77 and 64 mm Hg), and two groups with elevated ICP (30 and 50 mm Hg) and arterial hypertension (124 mm Hg). Intracranial hypertension was induced by continuous infusion of lactated Ringer's solution into the cisterna magna, arterial hypotension by controlled bleeding, and arterial hypertension by continuous administration of norepinephrine intravenously. Cerebral blood flow (CBF) was measured repetitively by the intraarterial 133Xe method at different levels of arterial PCO2. In each individual animal, CO2 reactivity was calculated from an exponential regression line obtained from the corresponding CBF/PaCO2 values. By plotting each individual value of CO2 reactivity against the corresponding CPP value from the seven investigation groups, CPP was significantly and directly related to CO2 reactivity of CBF (P < .001). No correlation was found by plotting CO2 reactivity values against the corresponding MABP values or the corresponding ICP values. Thus, the results show that CO2 reactivity is at least partially determined by CPP and that the impaired CO2 reactivity observed at intracranial hypertension and arterial hypotension may be caused by reduced CPP.
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Affiliation(s)
- J Hauerberg
- Department of Neurosurgery and The Neurobiology Research Unit, The Neuroscience Center, Rigshospitalet, Copenhagen, Denmark
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Barbier EL, Silva AC, Kim SG, Koretsky AP. Perfusion imaging using dynamic arterial spin labeling (DASL). Magn Reson Med 2001; 45:1021-9. [PMID: 11378880 DOI: 10.1002/mrm.1136] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Recently, a technique based on arterial spin labeling, called dynamic arterial spin labeling (DASL (Magn Reson Med 1999;41:299-308)), has been introduced to measure simultaneously the transit time of the labeled blood from the labeling plane to the exchange site, the longitudinal relaxation time of the tissue, and the perfusion of the tissue. This technique relies on the measurement of the tissue magnetization response to a time varying labeling function. The analysis of the characteristics of the tissue magnetization response (transit time, filling time constant, and perfusion) allows for quantification of the tissue perfusion and for transit time map computations. In the present work, the DASL scheme is used in conjunction with echo planar imaging at 4.7 T to produce brain maps of perfusion and transit time in the anesthetized rat, under graded hypercapnia. The data obtained show the variation of perfusion and transit time as a function of arterial pCO2. Based on the data, CO2 reactivity maps are computed. Published 2001 Wiley-Liss, Inc.
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Affiliation(s)
- E L Barbier
- Laboratory of Functional and Molecular Imaging and NIH MRI Research Facility, National Institute for Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1065, USA
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Kochanek PM, Hendrich KS, Robertson CL, Williams DS, Melick JA, Ho C, Marion DW, Jackson EK. Assessment of the effect of 2-chloroadenosine in normal rat brain using spin-labeled MRI measurement of perfusion. Magn Reson Med 2001; 45:924-9. [PMID: 11323821 DOI: 10.1002/mrm.1123] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Adenosine analogs such as 2-chloroadenosine are potent cerebrovasodilators. Spin-labeled MRI was used to investigate the spatial distribution, dose-response, and timing of the effect of 2-chloroadenosine on cerebral blood flow (CBF) after intraparenchymal injection into rat brain. Sprague-Dawley rats (N = 10) were injected with 2-chloroadenosine at doses of 0.3, 6.0, or 12 nmoles, or saline vehicle (2-4 microL). CBF was serially quantified in a slice through the injection site in a circular (3.6 mm diameter) region of interest (ROI) around the injection and in ipsilateral hemispheric ROIs at approximately 90 min and approximately 180 min. Marked 3.77- and 3.93-fold increases in CBF (vs. vehicle) were seen in the circular ROI at approximately 90 min and approximately 180 min after 12-nmol injection, respectively. Similarly, 2.92- and 2.78-fold increases in hemispheric CBF were observed at approximately 90 min and approximately 180 min, respectively, after injection of 12 nmoles. Linear dose-response relationships were observed at both times after injection in both ROIs (all P < 0.01). Spin-labeling MRI assessment revealed that parenchymal injection of 2-chloroadenosine produces potent, dose-dependent, and sustained vasodilation over large areas of brain. This treatment and imaging paradigm should facilitate investigation of the effect of CBF promotion in models of traumatic and ischemic brain injury.
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Affiliation(s)
- P M Kochanek
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA
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Abstract
Numerous techniques have been proposed in the last 15 years to measure various perfusion-related parameters in the brain. In particular, two approaches have proven extremely successful: injection of paramagnetic contrast agents for measuring cerebral blood volumes (CBV) and arterial spin labeling (ASL) for measuring cerebral blood flows (CBF). This review presents the methodology of the different magnetic resonance imaging (MRI) techniques in use for CBV and CBF measurements and briefly discusses their limitations and potentials.
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Affiliation(s)
- E L Barbier
- Laboratoire mixte INSERM U438, Université Joseph Fourier: RMN Bioclinique, LRC-CEA, Hôpital Albert Michallon, Grenoble, France
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Kroppenstedt SN, Stover JF, Unterberg AW. Effects of dopamine on posttraumatic cerebral blood flow, brain edema, and cerebrospinal fluid glutamate and hypoxanthine concentrations. Crit Care Med 2000; 28:3792-8. [PMID: 11153616 DOI: 10.1097/00003246-200012000-00004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVES Dopamine is often used in the treatment of traumatic brain injury to maintain cerebral perfusion pressure. However, it remains unclear whether dopamine contributes to secondary brain injury caused by vasoconstriction and resulting diminished cerebral perfusion. The present study investigated the effects of dopamine in different concentrations on posttraumatic cortical cerebral blood flow (CBF), brain edema formation, and cerebrospinal fluid concentrations of glutamate and hypoxanthine. DESIGN Randomized, placebo-controlled trial. SETTING Animal laboratory. SUBJECTS Eighteen male Sprague-Dawley rats subjected to a focal cortical brain injury. INTERVENTIONS Four hours after controlled cortical impact, rats were randomized to receive physiologic saline solution (n = 6), 10-12 tig/kg/min dopamine (n = 6), or 40-50 microg/kg/min dopamine (n = 6), for 3 hrs. Cortical CBF was measured over both hemispheres by using laser-Doppler flowmetry before trauma and before, during, and after the infusion period. At 8 hrs after trauma, brains were removed to determine hemispheric swelling and water content. Cisternal cerebrospinal fluid was sampled to measure glutamate and hypoxanthine. MEASUREMENTS AND MAIN RESULTS After trauma, cortical CBF was significantly decreased by 46% within the vicinity of the cortical contusion in all rats. Infusion of saline and 10-12 ig/kg/min dopamine did not change mean arterial blood pressure (MABP) or cortical CBF. However, infusion of 40-50 microg/kg/min dopamine, which elevated MABP from 89 to 120 mm Hg, significantly increased posttraumatic CBF within and around the contusion by 35%. Over the nontraumatized hemisphere, CBF remained unchanged. Hemispheric swelling, water content, cerebrospinal fluid glutamate, and hypoxanthine levels were not affected by dopamine in the given dosages. CONCLUSIONS Under the present study design, there was no evidence for a dopamine-mediated vasoconstriction, because posttraumatic cortical CBF was increased by dopamine-induced elevation of MABP. However, the increase in CBF did not significantly affect edema formation or cerebrospinal fluid glutamate and hypoxanthine levels.
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Affiliation(s)
- S N Kroppenstedt
- Department of Neurosurgery, Charité, Virchow Medical Center, Humboldt-University Berlin, Germany
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