Spectrin breakdown products in the cerebrospinal fluid in severe head injury--preliminary observations.
ABSTRACT Calcium-induced proteolytic processes are considered key players in the progressive pathobiology of traumatic brain injury (TBI). Activation of calpain and caspases after TBI leads to the cleavage of cytoskeletal proteins such as non-erythroid alpha II-spectrin. Recent reports demonstrate that the levels of spectrin and spectrin breakdown products (SBDPs) are elevated in vitro after mechanical injury, in the cerebrospinal fluid (CSF) and brain tissue following experimental TBI, and in human brain tissue after TBI.
This study was initiated to detect spectrin and SBDP accumulation in the ventricular CSF of 12 severe TBI-patients with raised intracranial pressure (ICP). Nine patients with non-traumatically elevated ICP and 5 undergoing diagnostic lumbar puncture (LP) served as controls. Intact spectrin and calpain and caspase specific SBDPs in CSF collected once a day over a several day period were assessed via Western blot analysis. Parameters of severity and outcome such as ICP, Glasgow Coma Scale and Glasgow Outcome Scale were also monitored in order to reveal a potential correlation between these CSF markers and clinical parameters.
In control patients undergone LP no immunoreactivity was detected. Non-erythroid alpha-II-spectrin and SBDP occurred more frequently and their level was significantly higher in the CSF of TBI patients than in other pathological conditions associated with raised ICP. Those TBI patients followed for several days post-injury revealed a consistent temporal pattern for protein accumulation with the highest level achieved on the 2(nd) -3(rd) days after TBI.
Elevation of calpain and caspase specific SBDPs is a significant finding in TBI patients indicating that intact brain spectrin- and SBDP-levels are closely associated with the specific neurochemical processes evoked by TBI. The results strongly support the potential utility of these surrogate markers in the clinical monitoring of patients with severe TBI and provide further evidence of the role of calcium-induced, calpain- and caspase-mediated structural proteolysis in TBI.
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ABSTRACT: The efficacy of the amphipathic ketoamide calpain inhibitor SNJ-1945 in attenuating calpain-mediated degradation of the neuronal cytoskeletal protein α-spectrin was examined in the controlled cortical impact (CCI) traumatic brain injury (TBI) model in male CF-1 mice. Using a single early (15 min after CCI-TBI) i.p. bolus administration of SNJ-1945 (6.25, 12.5, 25 or 50-mg/kg), we identified the most effective dose on α-spectrin degradation in the cortical tissue of mice at its 24 hr peak after severe CCI-TBI. We then investigated the effects of a pharmacokinetically-optimized regimen by examining multiple treatment paradigms that varied in dose and duration of treatment. Finally, using the most effective treatment regimen, the therapeutic window of α-spectrin degradation attenuation was assessed by delaying treatment from 15 min to 1 or 3 hr post-injury. The effect of SNJ-1945 on α-spectrin degradation exhibited a U-shaped dose-response curve when treatment was initiated 15 min post-TBI. The most effective 12.5 mg/kg dose of SNJ-1945 significantly reduced α-spectrin degradation by ~60% in cortical tissue. Repeated dosing of SNJ-1945 beginning with a 12.5 mg/kg dose did not achieve a more robust effect compared to a single bolus treatment, and the required treatment initiation was less than 1 hr. Although calpain has been firmly established to play a major role in posttraumatic secondary neurodegeneration, these data suggest that even brain and cell-permeable calpain inhibitors, when administered alone, do not possess sufficient cytoskeletal protective efficacy or a clinically practical therapeutic window after severe TBI. © 2012 The Authors Journal of Neurochemistry © 2012 International Society for Neurochemistry, J. Neurochem. (2012) 10.1111/jnc.12118.Journal of Neurochemistry 12/2012; · 3.97 Impact Factor
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ABSTRACT: Traumatic brain injury (TBI) is a major medical crisis without any FDA-approved pharmacological therapies that have been demonstrated to improve functional outcomes. It has been argued that discovery of disease-relevant biomarkers might help to guide successful clinical trials for TBI. Major advances in mass spectrometry (MS) have revolutionized the field of proteomic biomarker discovery and facilitated the identification of several candidate markers that are being further evaluated for their efficacy as TBI biomarkers. However, several hurdles have to be overcome even during the discovery phase which is only the first step in the long process of biomarker development. The high-throughput nature of MS-based proteomic experiments generates a massive amount of mass spectral data presenting great challenges in downstream interpretation. Currently, different bioinformatics platforms are available for functional analysis and data mining of MS-generated proteomic data. These tools provide a way to convert data sets to biologically interpretable results and functional outcomes. A strategy that has promise in advancing biomarker development involves the triad of proteomics, bioinformatics, and systems biology. In this review, a brief overview of how bioinformatics and systems biology tools analyze, transform, and interpret complex MS datasets into biologically relevant results is discussed. In addition, challenges and limitations of proteomics, bioinformatics, and systems biology in TBI biomarker discovery are presented. A brief survey of researches that utilized these three overlapping disciplines in TBI biomarker discovery is also presented. Finally, examples of TBI biomarkers and their applications are discussed.Frontiers in Neurology 01/2013; 4:61.
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ABSTRACT: Diffuse axonal injury (DAI) remains a prominent feature of human traumatic brain injury (TBI) and a major player in its subsequent morbidity. The importance of this widespread axonal damage has been confirmed by multiple approaches including postmortem neuropathology and advanced imaging capable of detecting the signatures of DAI across a spectrum of TBI in humans. Despite the increased interest in DAI and its implications for TBI patients, many questions remain about its pathogenesis and its therapeutic targeting. To address these deficiencies and to identify future directions needed to fill critical gaps in our understanding of DAI, the NINDS hosted a workshop in May 2011. This workshop sought to determine what is known regarding the pathogenesis of DAI in animal models of injury as well as in humnas. The workshop also addressed new tools to aid in the identification of DAI while also identifying therapeutic targets linked to DAI for continued preclinical investigation and ultimately, clinical translation. This report encapsulates the oral and written components of this workshop, addressing the key features regarding DAI, the biomechanics implicated in its initiating pathology, and those experimental animal modeling considerations that bear relevance to the biomechanical features of human TBI. Parallel considerations of alternate forms of DAI detection including advanced neuroimaging, electrophysiological, biomarker, and neurobehavioral evaluations are included, together with recommendations for how these technologies can be better integrated for a more comprehensive appreciation of the pathobiology of DAI and its overall structural and functional implications. Lastly, the document closes with a thorough review of the targets linked to the pathogenesis of DAI, while also presenting a detailed report of those target based therapies that have been utilized to date, with a consideration of their overall implications for future preclinical discovery and subsequent translation to the clinic.Journal of neurotrauma 12/2012; · 4.25 Impact Factor