Serum cleaved tau protein levels and clinical outcome in adult patients with closed head injury

Neurosurgical Breakthroughs of the Last 50 Years: A Historical Journey Through the Past and Present

This article presented the author's historical perspective on 25 of the most significant neurosurgical breakthrough events of the last 50 years. These breakthroughs have advanced neurosurgical patient care and management. They have improved the management of aneurysms, arteriovenous malformations, tumors, stroke, traumatic brain injury, movement disorders, epilepsy, hydrocephalus, and spine pathologies. Neurosurgery has evolved through research, innovation, and technology. Several neurosurgical breakthroughs were achieved using neuroendoscopy, neuronavigation, radiosurgery, endovascular techniques, and refinements in computer technology. With these breakthroughs, neurosurgery did not change; it just progressed. Neurosurgery should continue its progress through research to obtain new knowledge for the benefit of our patients.

Assessment of brain injury in cattle with Theileria annulata: Neuron-specific biomarkers, inflammation, oxidative stress and apoptosis

This study aimed to investigate selected brain-specific biomarkers in cattle with tropical theileriosis caused by Theileria annulata (T. annulata) and to evaluate their diagnostic and prognostic significance. The study group consisted of 25 cattle naturally infected with T. annulata, while the control group consisted of 10 healthy cattle. Animals with T. annulata were classified according to hematocrit (HCT) value as severe anemia group 1 (n:12) with HCT ≤12 and moderate anemia group 2 (n:13) with HCT between 13 and 24. Histopathological and immunohistochemical examinations of the brain tissue were performed in 10 nonsurvivor cattle. Serum calcium-binding protein B (S100B), glial fibrillary acidic protein (GFAP), tau protein and ubiquitin C-terminal hydrolase-1 (UCHL-1) concentrations in brain injury were measured using bovine-specific ELISA kits. S100B, GFAP, and Tau concentrations of cattle in the T. annulata group were found to be significantly higher than the control group (P<0.001). Brain specific biomarkers showed significant correlations with erythrocyte count, HCT and bilirubin. The presence of brain damage was confirmed by histopathological and immunohistochemical techniques. The results of ROC analysis showed that S100B with AUC value of 0.88 and GFAP with an AUC value of 0.82 were significant prognostic indicators. Additionally, S100B, GFAP and Tau showed significant diagnostic performance with an AUC value of 0.88, 0.92 and 0.86, respectively. In conclusion, brain-specific biomarkers can be used as diagnostic and prognostic markers in the assessment of brain damage in cattle naturally infected with T. annulata.

Correlation analysis between the amniotic fluid contamination and clinical grading of neonatal hypoxic-ischemic encephalopathy and biomarkers of brain damage

BACKGROUND

Amniotic fluid contamination (AFC) is a risk factor for neonatal hypoxic ischemic encephalopathy (HIE); however, the correlation between AFC level and the incidence and clinical grading of HIE, in addition to relevant biomarkers of brain damage, have not been assessed.

METHODS

This single-center observational study included 75 neonates with moderate-to-severe HIE. The neonates with HIE were divided into four subgroups according to the AFC level: normal amniotic fluid with HIE group (NAF-HIE), I°AFC with HIE group (I°AFC-HIE), II°AFC with HIE group (II°AFC-HIE), and III°AFC with HIE group (III°AFC-HIE). The control groups consisted of 35 healthy neonates. The clinical grading of neonatal HIE was performed according to the criteria of Sarnat and Sarnat. Serum tau protein and S100B were detected by enzyme-linked immunosorbent assay kits. Correlations of serum tau protein and S100B were evaluated using the Pearson correlation analysis.

RESULTS

(1) The incidence of neonatal HIE in the NAF-HIE group was 20 cases (26. 7%), I°AFC-HIE was 13 cases (17.3%), II°AFC-HIE was 10 cases (13.3%), and III°AFC-HIE was 32 cases (42. 7%). The incidence of moderate-to-severe HIE in the I°-III°AFC-HIE groups was 73.3% (55/75). (2) In 44 cases with severe HIE, 26 cases (59.1%) occurred in the III°AFC-HIE group, which had a significantly higher incidence of severe HIE than moderate HIE (p < 0.05). In NAF-HIE and I°AFC-HIE groups, the incidence of moderate HIE was 45.2% and 29.0%, respectively, which was higher than that of severe HIE (X2 = 9.2425, p < 0.05; X2 = 5.0472, p < 0.05, respectively). (3) Serum tau protein and S100B levels in the HIE groups were significantly higher than in the control group (all p < 0.05), and were significantly higher in the III°AFC-HIE group than in the NAF-HIE and I°AFC-HIE groups (all p < 0.05). (4) Serum tau protein and S100B levels in the severe HIE group were significantly higher in the moderate HIE group (all p < 0.05). (5) Serum tau protein and S100B levels were significantly positively correlated (r = 0.7703, p < 0.0001).

CONCLUSION

Among children with severe HIE, the incidence of III°AFC was higher, and the levels of serum tau protein and S100B were increased. AFC level might be associated with HIE grading.

Lack of association between four biomarkers and persistent post-concussion symptoms after a mild traumatic brain injury

Approximately 15 % of individuals who sustained a mild Traumatic Brain Injury (TBI) develop persistent post-concussion symptoms (PPCS). We hypothesized that blood biomarkers drawn in the Emergency Department (ED) could help predict PPCS. The main objective of this project was to measure the association between four biomarkers and PPCS at 90 days post mild TBI. We conducted a prospective cohort study in seven Canadian EDs. Patients aged ≥ 14 years presenting to the ED within 24 h of a mild TBI who were discharged were eligible. Clinical data and blood samples were collected in the ED, and a standardized questionnaire was administered 90 days later to assess the presence of symptoms. The following biomarkers were analyzed: S100B protein, Neuron Specific Enolase (NSE), cleaved-Tau (c-Tau) and Glial Fibrillary Acidic Protein (GFAP). The primary outcome measure was the presence of PPCS at 90 days after trauma. Relative risks and Areas Under the Curve (AUC) were computed. A total of 595 patients were included, and 13.8 % suffered from PPCS at 90 days. The relative risk of PPCS was 0.9 (95 % CI: 0.5-1.8) for S100B ≥ 20 pg/mL, 1.0 (95 % CI: 0.6-1.5) for NSE ≥ 200 pg/mL, 3.4 (95 % CI: 0.5-23.4) for GFAP ≥ 100 pg/mL, and 1.0 (95 % CI: 0.6-1.8) for C-Tau ≥ 1500 pg/mL. AUC were 0.50, 0.50, 0.51 and 0.54, respectively. Among mild TBI patients, S100B protein, NSE, c-Tau or GFAP do not seem to predict PPCS. Future research testing of other biomarkers is needed to determine their usefulness in predicting PPCS.

Prognosis and Diagnostic Biomarkers of Mild Traumatic Brain Injury: Current Status and Future Prospects

Mild traumatic brain injury (mTBI) is the most prevalent type of TBI (80-90%). It is characterized by a loss consciousness for less than 30 minutes, post-traumatic amnesia for less than 24 hours, and Glasgow Coma Score of 13-15. Accurately diagnosing mTBIs can be a challenge because the majority of these injuries do not show noticeable or visible changes on neuroimaging studies. Appropriate determination of mTBI is tremendously important because it might lead in some cases to post-concussion syndrome, cognitive impairments including attention, memory, and speed of information processing problems. The scientists have studied different methods to improve mTBI diagnosis and enhanced approaches that would accurately determine the severity of the trauma. The present review focuses on discussing the role of biomarkers as potential key factors in diagnosing mTBI. The present review focuses on 1) protein based peripheral and CNS markers, 2) genetic biomarkers, 3) imaging biomarkers, 4) neurophysiological biomarkers, and 5) the studies and clinical trials in mTBI. Each section provides information and characteristics on different biomarkers for mTBI.

Dynamics of Selected Biomarkers in Cerebrospinal Fluid During Complex Endovascular Aortic Repair - A Pilot Study

INTRODUCTION

Ischemic spinal cord injury (SCI) is a serious complication of complex aortic repair. Prophylactic cerebrospinal fluid (CSF) drainage, used to decrease lumbar cerebrospinal fluid (CSF) pressure, enables monitoring of CSF biomarkers that may aid in detecting impending SCI. We hypothesized that biomarkers, previously evaluated in traumatic SCI and brain injury, would be altered in CSF over time following complex endovascular aortic repair (cEVAR).

OBJECTIVES

To examine if a chosen cohort of CSF biomarker correlates to SCI and warrants further research.

METHODS

A prospective observational study on patients undergoing cEVAR with extensive aortic coverage. Vital parameters and CSF samples were collected on ten occasions during 72 hours post-surgery. A panel of ten biomarkers were analyzed (Neurofilament Light Polypeptide (NFL), Tau, Glial Fibrillary Acidic Protein (GFAP), Soluble Amyloid Precursos Protein (APP) α and β, Amyloid β 38, 40 and 42 (Aβ38, 40 and 42), Chitinase-3-like protein 1 (CHI3LI or YKL-40), Heart-type fatty acid binding protein (H-FABP).).

RESULTS

Nine patients (mean age 69, 7 males) were included. Median total aortic coverage was 68% [33, 98]. One patient died during the 30-day post-operative period. After an initial stable phase for the first few postoperative hours, most biomarkers showed an upward trend compared with baseline in all patients with >50% increase in value for NFL in 5/9 patients, in 7/9 patients for Tau and in 5/9 patients for GFAP. One patient developed spinal cord and supratentorial brain ischemia, confirmed with MRI. In this case, NF-L, GFAP and tau were markedly elevated compared with non-SCI patients (maximum increase compared with baseline in the SCI patient versus mean value of the maximal increase for all other patients: NF-L 367% vs 79%%, GFAP 95608% versus 3433%, tau 1020% vs 192%).

CONCLUSION

This study suggests an increase in all ten studied CSF biomarkers after coverage of spinal arteries during endovascular aortic repair. However, the pilot study was not able to establish a specific correlation between spinal fluid biomarker elevation and clinical symptoms of SCI due to small sample size and event rate.

Molecular and Diffusion Tensor Imaging Biomarkers of Traumatic Brain Injury: Principles for Investigation and Integration

The last 20 years have seen the advent of new technologies that enhance the diagnosis and prognosis of traumatic brain injury (TBI). There is recognition that TBI affects the brain beyond initial injury, in some cases inciting a progressive neuropathology that leads to chronic impairments. Medical researchers are now searching for biomarkers to detect and monitor this condition. Perhaps the most promising developments are in the biomolecular and neuroimaging domains. Molecular assays can identify proteins indicative of neuronal injury and/or degeneration. Diffusion imaging now allows sensitive evaluations of the brain's cellular microstructure. As the pace of discovery accelerates, it is important to survey the research landscape and identify promising avenues of investigation. In this review, we discuss the potential of molecular and diffusion tensor imaging (DTI) biomarkers in TBI research. Integration of these technologies could advance models of disease prognosis, ultimately improving care. To date, however, few studies have explored relationships between molecular and DTI variables in patients with TBI. Here, we provide a short primer on each technology, review the latest research, and discuss how these biomarkers may be incorporated in future studies.

Study on serum Tau protein level and neurodevelopmental outcome of placental abruption with neonatal hypoxic-ischemic encephalopathy

Objective: The aim of this study was to explore differences in serum Tau protein levels and neurodevelopmental prognoses of placental abruption or umbilical cord around neck with hypoxic-ischemic encephalopathy (HIE).Methods: Forty neonates with moderate/severe HIE divided into placental abruption with HIE group (placental abruption with hypoxic-ischemic encephalopathy (PA-HIE) group) (n = 18) and umbilical cord around the neck with HIE group (umbilical cord around the neck with hypoxic-ischemic encephalopathy (UCAN-HIE) group) (n = 22). Healthy term newborns comprised the control group (n = 35). Serum Tau protein levels were measured using an enzyme-linked immunosorbent assay 24 hours (3.50 hours [1.00-24.00]) after birth. Neurodevelopment outcomes were assessed based on the Gesell Developmental Scale at 9 months of age.Results: Serum Tau protein levels were significantly higher in 40 cases (1013 pg/ml [538.04-1190.42]) than in the control group (106.41 pg/ml [64.55-154.71], p = .0001). Serum Tau protein levels in the PA-HIE group (1024.46 pg/ml [657.88-1190.42]) were significantly higher than those in the UCAN-HIE group (892.78 pg/ml [538.04-1179.50], p = .0149). The development quotient score in the PA-HIE group (67.0 [47.0-90.0]) was significantly lower than that in the UCAN-HIE group (81.5 [52.6-100.0]) (p = .0028). The component ratio of neurodevelopmental retardation in the PA-HIE group (44.45%) was significantly higher than that in the UCAN-HIE group (22.73%) (X² = 13.3138, p = .0013).Conclusions: Compared with the UCAN-HIE group, the serum Tau protein level and the component ratio of neurodevelopmental retardation were significantly higher in the PA-HIE group.

An update on the association between traumatic brain injury and Alzheimer's disease: Focus on Tau pathology and synaptic dysfunction

L.P. Li, J.W. Liang and H.J. Fu. An update on the association between traumatic brain injury and Alzheimer's disease: Focus on Tau pathology and synaptic dysfunction. NEUROSCI BIOBEHAV REVXXX-XXX,2020.-Traumatic brain injury (TBI) and Alzheimer's disease (AD) are devastating conditions that have long-term consequences on individual's cognitive functions. Although TBI has been considered a risk factor for the development of AD, the link between TBI and AD is still in debate. Aggregation of hyperphosphorylated tau and intercorrelated synaptic dysfunction, two key pathological elements in both TBI and AD, play a pivotal role in mediating neurodegeneration and cognitive deficits, providing a mechanistic link between these two diseases. In the first part of this review, we analyze the experimental literatures on tau pathology in various TBI models and review the distribution, biological features and mechanisms of tau pathology following TBI with implications in AD pathogenesis. In the second part, we review evidences of TBI-mediated structural and functional impairments in synapses, with a focus on the overlapped mechanisms underlying synaptic abnormalities in both TBI and AD. Finally, future perspectives are proposed for uncovering the complex relationship between TBI and neurodegeneration, and developing potential therapeutic avenues for alleviating cognitive deficits after TBI.

High Serum Levels of Serum 100 Beta Protein, Neuron-specific Enolase, Tau, Active Caspase-3, M30 and M65 in Children with Autism Spectrum Disorders

Objective

The purpose of this study was therefore to investigate whether neuronal, axonal, and glial cell markers (Neuron-specific enolase [NSE], tau, serum 100 beta protein [S100B], respectively) and apoptosis markers (active caspase 3, M30, M65) and whether these parameters can be used as diagnostic biomarkers in autism spectrum disorders (ASD).

Methods

This study measured the serum S100B, NSE, tau, active caspase 3, M30, and M65 levels in 43 patients with ASD (aged 3−12 years) and in 41 age- and sex-matched healthy controls. ASD severity was rated using the Childhood Autism Rating Scale. The serum levels were determined in the biochemistry laboratory using the ELISA technique. The receiver operator characteristics curve method was employed to evaluate the accuracy of the parameters in diagnosing ASD.

Results

Serum S100B, tau, NSE, active caspase-3, M30, and M65 levels were significantly higher in the patient group than in the control group (p < 0.001, p = 0.002, p = 0.002, p = 0.005, p < 0.001, and p = 0.004, respectively). The cut-off value of S100B was 48.085 pg/ml (sensitivity: 74.4%, specificity: 80.5%, areas under the curve: 0.879, p < 0.001).

Conclusion

Apoptosis increased in children with ASD, and neuronal, axonal, and glial cell injury was observed. In addition, S100B may be an important diagnostic biomarker in patients with ASD. Apoptosis, and neuronal, axonal and astrocyte pathologies may play a significant role in the pathogenesis of ASD, and further studies are now required to confirm this.

The prognostic value of the Tau protein serum level in metastatic breast cancer patients and its correlation with brain metastases

Background

Metastatic breast cancer (MBC) prognosis is variable, depending on several clinical and biological factors. A better prediction of a patient’s outcome could allow for a more accurate choice of treatments. The role of serum biomarkers in predicting outcome remains unclear in this setting. Tau, a microtubule-associated protein, is a neuronal marker that is also expressed in normal breast epithelial cells and cancer cells. Its tissue expression is associated with prognosis in MBC. However, the prognostic value of Tau serum levels in these patients is unknown. We aimed at evaluating the prognostic value of Tau (and other classical biomarkers) in MBC patients, and to assess its association with the presence of brain metastases (BM).

Methods

244 MBC patients treated at our institution (2007–2015) were retrospectively selected. The usual MBC clinical and pathological variables were collected, altogether with CA15–3, CEA and HER2 extra-cellular domain (ECD) serum levels. Tau serum levels were measured with a novel immunoassay (digital ELISA) using Single Molecule Array (Simoa) technology. Overall survival (OS) was estimated with the Kaplan-Meier method. To investigate prognostic factors, a multivariate analysis was performed. Cut-offs were set using the Youden index method associated with receiver-operating characteristics (ROC) curves to evaluate the accuracy of biomarkers to identify patients with BM.

Results

With a median follow-up of 40.8 months, median OS was 15.5 months (95%CI 12.4–20.2). Elevated serum levels of Tau were independently associated with a poor outcome in the whole population as well as in patients with (n = 86) and without BM (n = 158). Median serum Tau levels tended to be higher in patients with BM (p = 0.23). In univariate analysis, patients with BM had an increased risk of serum Tau > 3.17 pg/mL (OR = 2.2, p = 0.049). In multivariate analysis, high values of Tau (OR = 3.98, p = 0.034) accurately identified patients with BM in our cohort.

Conclusions

Tau is a new biomarker of interest in MBC. Its serum level could represent an independent prognostic factor in these patients (both with and without BM). It also seems to be associated with the presence of BM. A validation of these results in an independent set of MBC patients is necessary to confirm these findings.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5287-z) contains supplementary material, which is available to authorized users.

CNS Injury: Posttranslational Modification of the Tau Protein as a Biomarker

The ideal biomarker for central nervous system (CNS) trauma in patients would be a molecular marker specific for injured nervous tissue that would provide a consistent and reliable assessment of the presence and severity of injury and the prognosis for recovery. One candidate biomarker is the protein tau, a microtubule-associated protein abundant in the axonal compartment of CNS neurons. Following axonal injury, tau becomes modified primarily by hyperphosphorylation of its various amino acid residues and cleavage into smaller fragments. These posttrauma products can leak into the cerebrospinal fluid or bloodstream and become candidate biomarkers of CNS injury. This review examines the primary molecular changes that tau undergoes following traumatic brain injury and spinal cord injury, and reviews the current literature in traumatic CNS biomarker research with a focus on the potential for hyperphosphorylated and cleaved tau as sensitive biomarkers of injury.

Review of the potential use of blood neuro-biomarkers in the diagnosis of mild traumatic brain injury

Head injury is a common presenting complaint amongst emergency department patients. To date, there has been no widespread utilization of neuro-biomarkers to aid the diagnosis of traumatic brain injury. This review article explores which neuro-biomarkers could be used in the emergency department in aiding the clinical diagnosis of mild traumatic brain injury. Based on the available evidence, the most promising neuro-biomarkers appear to be Glial fibrillary acidic protein (GFAP) and Ubiquitin C-Terminal Hydrolase Isozyme L1 (UCH-L1) as these show significant rises in peripheral blood levels shortly after injury and these have been demonstrated to correlate with long-term clinical outcomes. Treatment strategies for minor traumatic brain injury in the emergency department setting are not well developed. The introduction of blood neuro-biomarkers could reduce unnecessary radiation exposure and provide an opportunity to improve the care of this patient group.

Prognostic utility of neuroinjury biomarkers in post out-of-hospital cardiac arrest (OHCA) patient management

Despite aggressive intervention, patients who survive an out-of-hospital cardiac arrest (OHCA) generally have very poor prognoses, with nationwide survival rates of approximately 10-20%. Approximately 90% of survivors will have moderate to severe neurological injury ranging from moderate cognitive impairment to brain death. Currently, few early prognostic indicators are considered reliable enough to support patients' families and clinicians' in their decisions regarding medical futility. Blood biomarkers of neurological injury after OHCA may be of prognostic value in these cases. When most bodily tissues are oxygen-deprived, cellular metabolism switches from aerobic to anaerobic respiration. Neurons are a notable exception, however, being dependent solely upon aerobic respiration. Thus, after several minutes without circulating oxygen, neurons sustain irreversible damage, and certain measurable biomarkers are released into the circulation. Prior studies have demonstrated value in blood biomarkers in prediction of survival and neurologic impairment after OHCA. We hypothesize that understanding peptide biomarker kinetics in the early return of spontaneous circulation (ROSC) period, especially in the setting of refractory cardiac arrest, may assist clinicians in determining prognosis earlier in acute resuscitation. Specifically, during and after immediate resuscitation and return of ROSC, clinicians and families face a series of important questions regarding patient prognosis, futility of care and allocation of scarce resources such as the early initiation of extracorporeal cardiopulmonary resuscitation (ECPR). The ability to provide early prognostic information in this setting is highly valuable. Currently available, as well as potential biomarkers that could be good candidates in prognostication of neurological outcomes after OHCA or in the setting of refractory cardiac arrest will be reviewed and discussed.

Science is 1% inspiration and 99% biomarkers

Neurodegeneration plays a key role in multiple sclerosis (MS) contributing to long-term disability in patients. The prognosis is, however, unpredictable coloured by complex disease mechanisms which can only be clearly appreciated using biomarkers specific to pathobiology of the underlying process. Here, we describe six promising neurodegenerative biomarkers in MS (neurofilament proteins, neurofilament antibodies, tau, N-acetylaspartate, chitinase and chitinase-like proteins and osteopontin), critically evaluating the evidence using a modified Bradford Hill criteria.

Potential Blood-based Biomarkers for Concussion

Mounting research in the field of sports concussion biomarkers has led to a greater understanding of the effects of brain injury from sports. A recent systematic review of clinical studies examining biomarkers of brain injury following sports-related concussion established that almost all studies have been published either in or after the year 2000. In an effort to prevent chronic traumatic encephalopathy and long-term consequences of concussion, early diagnostic and prognostic tools are becoming increasingly important; particularly in sports and in military personnel, where concussions are common occurrences. Early and tailored management of athletes following a concussion with biomarkers could provide them with the best opportunity to avoid further injury. Should blood-based biomarkers for concussion be validated and become widely available, they could have many roles. For instance, a point-of-care test could be used on the field by trained sport medicine professionals to help detect a concussion. In the clinic or hospital setting, it could be used by clinicians to determine the severity of concussion and be used to screen players for neuroimaging (computed tomography and/or magnetic resonance imaging) and further neuropsychological testing. Furthermore, biomarkers could have a role in monitoring progression of injury and recovery and in managing patients at high risk of repeated injury by being incorporated into guidelines for return to duty, work, or sports activities. There may even be a role for biomarkers as surrogate measures of efficacy in the assessment of new treatments and therapies for concussion.

A prospective pilot study on serum cleaved tau protein as a neurological marker in severe traumatic brain injury

OBJECTIVE

Neurotrauma has been labelled as a "silent epidemic" affecting both the developed and the developing nations. To date, no single brain-specific biomarker has been unanimously accepted for routine clinical use in TBI. Our study aims to determine the correlation of "cleaved-tau protein" in severe traumatic brain injury (TBI) with Glasgow Coma Scale (GCS) at the time of admission, mode of injury, CT findings and outcome at discharge.

METHODS

The study has been approved by the institutional ethical committee. 40 cases with severe TBI and 40 randomly selected healthy controls were included in this prospective study. Venous blood samples were collected and serum cleaved tau protein levels were measured and correlated with gender, mode of injury, CT findings GCS score and GOS score at discharge.

RESULTS

In the severe TBI group, the mean serum cleaved tau protein levels in males were 91.65 ± 41.34 pg/ml (mean ± S.D.), and females were 104.43 ± 53.08 pg/ml (mean ± S.D.), (p = 0.27). Mean serum C-tau level in study group was 95.48 ± 44.87 pg/ml (range 36.44-192.34), 95% C.I. (81.13-109.83) and in controls was 33.82 ± 13.65 pg/ml (range 2.48-66.54), 95% C.I. (29.46-38.19) (p < 0.001). The distribution of serum C-tau was in severe TBI group varied in all categories of GCS at 0th day (p < 0.001). Serum cleaved tau protein levels in the good outcome group were 74.26 ± 25.43 pg/ml (mean ± S.D.), range 36.44-144.54, 95% C.I. (63.52-85.00) and the poor-outcome group were 127.32 ± 49.40 pg/ml, range 66.65-192.34, 95% C.I. (100.99-153.64) (p = 0.001).

CONCLUSION

In severe TBI, serum cleaved tau protein levels were significantly higher as compared to the controls in this prospective study. However, results of this study are preliminary in nature and there is a need to undertake larger prospective studies to reach a definitive conclusion.

MicroRNAs as diagnostic markers and therapeutic targets for traumatic brain injury

Traumatic brain injury (TBI) is characterized by primary damage to the brain from the external mechanical force and by subsequent secondary injury due to various molecular and pathophysiological responses that eventually lead to neuronal cell death. Secondary brain injury events may occur minutes, hours, or even days after the trauma, and provide valuable therapeutic targets to prevent further neuronal degeneration. At the present time, there is no effective treatment for TBI due, in part, to the widespread impact of numerous complex secondary biochemical and pathophysiological events occurring at different time points following the initial injury. MicroRNAs control a range of physiological and pathological functions such as development, differentiation, apoptosis and metabolism, and may serve as potential targets for progress assessment and intervention against TBI to mitigate secondary damage to the brain. This has implications regarding improving the diagnostic accuracy of brain impairment and long-term outcomes as well as potential novel treatments. Recent human studies have identified specific microRNAs in serum/plasma (miR-425-p, -21, -93, -191 and -499) and cerebro-spinal fluid (CSF) (miR-328, -362-3p, -451, -486a) as possible indicators of the diagnosis, severity, and prognosis of TBI. Experimental animal studies have examined specific microRNAs as biomarkers and therapeutic targets for moderate and mild TBI (e.g., miR-21, miR-23b). MicroRNA profiling was altered by voluntary exercise. Differences in basal microRNA expression in the brain of adult and aged animals and alterations in response to TBI (e.g., miR-21) have also been reported. Further large-scale studies with TBI patients are needed to provide more information on the changes in microRNA profiles in different age groups (children, adults, and elderly).

Autophagy Modulation by Lanthionine Ketimine Ethyl Ester Improves Long-Term Outcome after Central Fluid Percussion Injury in the Mouse

Diffuse axonal injury is recognized as a progressive and long-term consequence of traumatic brain injury. Axonal injury can have sustained negative consequences on neuronal functions such as anterograde and retrograde transport and cellular processes such as autophagy that depend on cytoarchitecture and axon integrity. These changes can lead to somatic atrophy and an inability to repair and promote plasticity. Obstruction of the autophagic process has been noted after brain injury, and rapamycin, a drug used to stimulate autophagy, has demonstrated positive effects in brain injury models. The optimization of drugs to promote beneficial autophagy without negative side effects could be used to attenuate traumatic brain injury and promote improved outcome. Lanthionine ketimine ethyl ester, a bioavailable derivative of a natural sulfur amino acid metabolite, has demonstrated effects on autophagy both in vitro and in vivo. Thirty minutes after a moderate central fluid percussion injury and throughout the survival period, lanthionine ketimine ethyl ester was administered, and mice were subsequently evaluated for learning and memory impairments and biochemical and histological changes over a 5-week period. Lanthionine ketimine ethyl ester, which we have shown previously to modulate autophagy markers and alleviate pathology and slow cognitive decline in the 3 × TgAD mouse model, spared cognition and pathology after central fluid percussion injury through a mechanism involving autophagy modulation.

Increased cerebrospinal fluid cleaved tau protein (C-tau) levels suggest axonal damage in pediatric patients with brain tumors

OBJECTIVE

This study aims to determine if cerebrospinal fluid/serum cleaved tau protein and CSF 9-hydroxyoctadecadienoic acid levels, reflecting potential biomarkers of overall neuronal injury and lipid peroxidation, respectively, are elevated in brain tumor patients compared with controls.

DESIGN

This article is a prospective clinical observational study.

SETTING

This study is conducted at a tertiary-care children's hospital.

PATIENTS

Our participants are children younger than or equal to 18 years of age undergoing brain tumor surgery.

MEASUREMENTS AND MAIN RESULTS

During the study period, 26 consecutive patients newly diagnosed with brain tumors who met the inclusion criteria were prospectively enrolled. Baseline cerebrospinal fluid analysis of cleaved tau and 9-hydroxyoctadecadienoic acid were measured in 15 patients. Cerebrospinal fluid cleaved tau and 9-hydroxyoctadecadienoic acid levels were measured in 22 patients for post-surgery days 1 and 3. Serum cleaved tau levels were measured for 20 and 18 patients for post-surgery days 1 and 3, respectively. The presence of a brain tumor significantly increased the baseline cerebrospinal fluid cleaved tau levels but did not affect cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels. Similarly, there was a significant increase in post-surgery day 1 cerebrospinal fluid cleaved tau levels from baseline (p = 0.01) and a trend toward significant decrease in post-surgery day 3 cerebrospinal fluid cleaved tau from day 1 (p = 0.07). 9-Hydroxyoctadecadienoic acid concentrations remained relatively constant over time with no differences noted between the control and brain tumor patients. There was a trend towards a significant association between cerebrospinal fluid cleaved tau levels and duration of symptoms (p = 0.07).

CONCLUSIONS

Cerebrospinal fluid cleaved tau levels in children with newly diagnosed brain tumors exhibit markedly elevated cerebrospinal fluid cleaved tau levels, suggesting axonal damage. This axonal injury does not seem to correlate with lipid peroxidation at least when as assessed by cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels. There was no association found between the biomarkers and multiple independent variables obtained at pre- and post-tumor resection.

The Glymphatic System: A Beginner's Guide

The glymphatic system is a recently discovered macroscopic waste clearance system that utilizes a unique system of perivascular tunnels, formed by astroglial cells, to promote efficient elimination of soluble proteins and metabolites from the central nervous system. Besides waste elimination, the glymphatic system also facilitates  brain-wide distribution of several compounds, including glucose, lipids, amino acids, growth factors, and neuromodulators. Intriguingly, the glymphatic system function mainly during sleep and is largely disengaged during wakefulness. The biological need for sleep across all species may therefore reflect that the brain must enter a state of activity that enables elimination of potentially neurotoxic waste products, including β-amyloid. Since the concept of the glymphatic system is relatively new, we will here review its basic structural elements, organization, regulation, and functions. We will also discuss recent studies indicating that glymphatic function is suppressed in various diseases and that failure of glymphatic function in turn might contribute to pathology in neurodegenerative disorders, traumatic brain injury and stroke.

Emerging themes from the literature on circulating biomarkers of traumatic brain injury

ABSTRACT 

Objective diagnosis of traumatic brain injury (TBI) and early prediction of TBI-associated outcome remains a significant clinical challenge with major public health implications. The use of circulating biomarkers to quantify TBI has promise for real-time clinical decision making and may help clinicians determine the need for advanced imaging, and guide an individualized approach to the management of TBI. In this review of the literature, we provide an overview of candidate TBI biomarkers and discuss several themes emerging from the literature on TBI biomarkers. We suggest that the future utility of TBI biomarkers lies in the creation of composite panels of biomarkers tailored to the pursuit of specific clinic questions.

Serum tau protein as a marker of disease activity in enterohemorrhagic Escherichia coli O111-induced hemolytic uremic syndrome

Tau protein levels in cerebrospinal fluid (CSF) and serum are elevated in patients with various central nervous system diseases. We investigated whether serum tau protein levels are useful for predicting and assessing disease activity of acute encephalopathy (AE) in enterohemorrhagic Escherichia coli (EHEC) O111-induced hemolytic uremic syndrome (HUS; EHEC encephalopathy). Serum samples were obtained from 14 patients with EHEC O111/HUS, 20 patients with non-EHEC-related AE, and 20 age- and sex-matched healthy controls. CSF samples were obtained from 2 patients with EHEC encephalopathy and 20 patients with non-EHEC-related AE. Tau protein levels and levels of several proinflammatory cytokines were quantified by enzyme-linked immunosorbent assays. Results were compared with the clinical features of EHEC encephalopathy, including magnetic resonance image (MRI) findings. Serum tau levels in patients with EHEC encephalopathy were significantly elevated compared with those in patients with EHEC O111/HUS without encephalopathy, patients with non-EHEC-related AE, and healthy controls. The ratio of CSF tau levels to serum tau levels was >1.0 in all patients with non-EHEC-related AE but <1.0 in 2 patients with EHEC encephalopathy. Serum tau protein levels increased rapidly and markedly in patients with severe EHEC 0111/HUS and encephalopathy when HUS occurred, but were not elevated in mild patients, even in the HUS phase. Furthermore, changes in serum tau protein levels in patients with EHEC encephalopathy were consistent with abnormalities on brain MRI and were positively correlated with proinflammatory cytokine levels. Our results indicate that serum tau protein might be useful to predict and assess disease activity of EHEC encephalopathy.

Systematic review of clinical studies examining biomarkers of brain injury in athletes after sports-related concussion

The aim of this study was to systematically review clinical studies examining biofluid biomarkers of brain injury for concussion in athletes. Data sources included PubMed, MEDLINE, and the Cochrane Database from 1966 to October 2013. Studies were included if they recruited athletes participating in organized sports who experienced concussion or head injury during a sports-related activity and had brain injury biomarkers measured. Acceptable research designs included experimental, observational, and case-control studies. Review articles, opinion papers, and editorials were excluded. After title and abstract screening of potential articles, full texts were independently reviewed to identify articles that met inclusion criteria. A composite evidentiary table was then constructed and documented the study title, design, population, methods, sample size, outcome measures, and results. The search identified 52 publications, of which 13 were selected and critically reviewed. All of the included studies were prospective and were published either in or after the year 2000. Sports included boxing (six studies), soccer (five studies), running/jogging (two studies), hockey (one study), basketball (one study), cycling (one study), and swimming (one study). The majority of studies (92%) had fewer than 100 patients. Three studies (23%) evaluated biomarkers in cerebrospinal fluid (CSF), one in both serum and CSF, and 10 (77%) in serum exclusively. There were 11 different biomarkers assessed, including S100β, glial fibrillary acidic protein, neuron-specific enolase, tau, neurofilament light protein, amyloid beta, brain-derived neurotrophic factor, creatine kinase and heart-type fatty acid binding protein, prolactin, cortisol, and albumin. A handful of biomarkers showed a correlation with number of hits to the head (soccer), acceleration/deceleration forces (jumps, collisions, and falls), postconcussive symptoms, trauma to the body versus the head, and dynamics of different sports. Although there are no validated biomarkers for concussion as yet, there is potential for biomarkers to provide diagnostic, prognostic, and monitoring information postinjury. They could also be combined with neuroimaging to assess injury evolution and recovery.

Serum tau protein level serves as a predictive factor for neurological prognosis in neonatal asphyxia

BACKGROUND

Tau protein is a microtubule-associated protein that is present in axons. Elevated tau protein levels in cerebrospinal fluid or serum are associated with several central nervous system diseases and can indicate neuronal injury.

OBJECTIVE

In the present study, we measured and then compared serum tau protein levels between infants with neonatal asphyxia and control subjects. We examined these data to investigate the correlation between serum tau protein levels and neurological outcomes after neonatal asphyxia.

PATIENTS AND METHODS

Serum tau protein levels were determined by an enzyme-linked immunosorbent assay in 19 neonates with neonatal asphyxia. Of these 19 neonates, 3 had severe spastic tetraplegia, and 1 had west syndrome. A group of 19 unaffected neonates was included in the study as a control group.

RESULTS

Serum tau protein levels on postnatal day 3 were significantly higher in the poor outcome group than those in the good outcome (p=0.010) and control groups (p=0.006). On postnatal day 7, serum tau protein levels again were significantly higher in the poor outcome group than those in the good outcome (p=0.007) and control groups (p=0.006).

CONCLUSIONS

The present findings indicate serum tau protein levels measured on postnatal days 3 and 7 can predict neurological prognosis following neonatal asphyxia.

Aortic Stiffness Is Related to the Ischemic Brain Injury Biomarker N-Methyl-D-aspartate Receptor Antibody Levels in Aortic Valve Replacement

Background. Aortic stiffness changes the flow pattern of circulating blood causing microvascular damage to different end-organ tissues, such as brain cells. The relationship between aortic stiffness measured by pulse wave velocity (PWV) and serum ischemic brain injury biomarker N-methyl-D-aspartate receptor antibody (NR2Ab) levels in aortic valve replacement has not been assessed. Methods. Patients undergoing aortic valve replacement (AVR) for aortic stenosis (AS) had their PWV and NR2Ab serum levels measured preoperatively. We analyzed PWV and NR2Ab in two ways: (1) as continuous variables using the actual value and (2) as dichotomous variables (PWV-norm and PWV-high groups) and (NR2Ab-low and NR2Ab-high groups). Results. Fifty-six patients (71 ± 8.4 years) were included in this study. The NR2Ab level (ng/mL) was significantly higher in the PWV-high group (n = 21) than in PWV-norm group (n = 35; median 1.8 ± 1.2 versus 1.2 ± 0.7, resp., P = 0.003). NR2Ab level was positively associated with PWV and negatively associated with male gender. Multiple regression revealed PWV independently related to NR2Ab level, and PWV cut-off was associated with a 7.23 times increase in the likelihood of having high NR2Ab (>1.8 ng/mL). Conclusion. Higher PWV in patients with surgical aortic stenosis is associated with higher levels of the ischemic brain biomarker NR2Ab.

Evaluation of serum phosphorylated neurofilament subunit NF-H as a prognostic biomarker in dogs with thoracolumbar intervertebral disc herniation

OBJECTIVE

To investigate whether pNF-H is a prognostic biomarker of spinal cord injury (SCI) in paraplegic dogs with thoracolumbar intervertebral disc herniation (IVDH).

STUDY DESIGN

Prospective, case-control clinical study

ANIMALS

Dogs (n = 60) with SCI from IVDH and 6 healthy dogs.

METHODS

Serum from 60 thoracolumbar IVDH dogs (Grade 4: 22 dogs; Grade 5: 38 dogs) collected 1-3 days after injury, and 6 control dogs, was analyzed using enzyme-linked immunosorbent assay (ELISA) against a phosphorylated form of the high-molecular-weight neurofilament subunit NF-H (pNF-H). Serum pNF-H levels were compared between different IVDH grades and their prognostic value was investigated.

RESULTS

pNF-H levels were significantly greater in Grade 5 than Grade 4 dogs. There were significant differences in pNF-H levels between dogs that regained voluntarily ambulation and those that did not. All 8 dogs that had high pNF-H levels 1-3 days after injury did not regain the ability to walk after surgery.

CONCLUSIONS

Serum pNF-H levels might be a biomarker for predicting prognosis of canine SCI.

Amyloid-β Peptides and Tau Protein as Biomarkers in Cerebrospinal and Interstitial Fluid Following Traumatic Brain Injury: A Review of Experimental and Clinical Studies

Traumatic brain injury (TBI) survivors frequently suffer from life-long deficits in cognitive functions and a reduced quality of life. Axonal injury, observed in many severe TBI patients, results in accumulation of amyloid precursor protein (APP). Post-injury enzymatic cleavage of APP can generate amyloid-β (Aβ) peptides, a hallmark finding in Alzheimer’s disease (AD). At autopsy, brains of AD and a subset of TBI victims display some similarities including accumulation of Aβ peptides and neurofibrillary tangles of hyperphosphorylated tau proteins. Most epidemiological evidence suggests a link between TBI and AD, implying that TBI has neurodegenerative sequelae. Aβ peptides and tau may be used as biomarkers in interstitial fluid (ISF) using cerebral microdialysis and/or cerebrospinal fluid (CSF) following clinical TBI. In the present review, the available clinical and experimental literature on Aβ peptides and tau as potential biomarkers following TBI is comprehensively analyzed. Elevated CSF and ISF tau protein levels have been observed following severe TBI and suggested to correlate with clinical outcome. Although Aβ peptides are produced by normal neuronal metabolism, high levels of long and/or fibrillary Aβ peptides may be neurotoxic. Increased CSF and/or ISF Aβ levels post-injury may be related to neuronal activity and/or the presence of axonal injury. The heterogeneity of animal models, clinical cohorts, analytical techniques, and the complexity of TBI in the available studies make the clinical value of tau and Aβ as biomarkers uncertain at present. Additionally, the link between early post-injury changes in tau and Aβ peptides and the future risk of developing AD remains unclear. Future studies using methods such as rapid biomarker sampling combined with enhanced analytical techniques and/or novel pharmacological tools could provide additional information on the importance of Aβ peptides and tau protein in both the acute pathophysiology and long-term consequences of TBI.

Serum cleaved tau protein and traumatic mild head injury: a preliminary study in the Thai population

PURPOSE

To determine the correlation between serum cleaved tau protein and traumatic mild head injury (MHI) (GCS 13-15).

METHODS

A prospective observational study was conducted. Blood specimens from 12 healthy persons and 44 adult patients with traumatic MHI were collected in the emergency department to measure the cleaved tau protein level using a Human Tau phosphoSerine 396 ELISA kit. A brain computed tomography (CT) scan was done in all patients. The serum cleaved tau protein level was considered positive at a cut-off point of 0.1 pg/ml. An intracranial lesion was defined as any abnormality detected by brain CT scan.

RESULTS

The mean age of the traumatic MHI patients was 34.9 ± 15.6 years (range 15-74). The median GCS was 15. The median time from injury to arrival at the emergency department was 30 min. There were 11 intracranial lesions detected by brain CT scan (25.0 %). Serum cleaved tau protein was not detected in either healthy or traumatic MHI patients.

CONCLUSION

As it was uncorrelated with traumatic MHI, serum cleaved tau protein proved to be an unreliable biomarker to use in the early detection of and decision-making for traumatic MHI patients at the emergency department.

Biomarkers for the clinical differential diagnosis in traumatic brain injury--a systematic review

Rapid triage and decision-making in the treatment of traumatic brain injury (TBI) present challenging dilemma in "resource poor" environments such as the battlefield and developing areas of the world. There is an urgent need for additional tools to guide treatment of TBI. The aim of this review is to establish the possible use of diagnostic TBI biomarkers in (1) identifying diffuse and focal brain injury and (2) assess their potential for determining outcome, intracranial pressure (ICP), and responses to therapy. At present, there is insufficient literature to support a role for diagnostic biomarkers in distinguishing focal and diffuse injury or for accurate determination of raised ICP. Presently, neurofilament (NF), S100β, glial fibrillary acidic protein (GFAP), and ubiquitin carboxyl terminal hydrolase-L1 (UCH-L1) seemed to have the best potential as diagnostic biomarkers for distinguishing focal and diffuse injury, whereas C-tau, neuron-specific enolase (NSE), S100β, GFAP, and spectrin breakdown products (SBDPs) appear to be candidates for ICP reflective biomarkers. With the combinations of different pathophysiology related to each biomarker, a multibiomarker analysis seems to be effective and would likely increase diagnostic accuracy. There is limited research focusing on the differential diagnostic properties of biomarkers in TBI. This fact warrants the need for greater efforts to innovate sensitive and reliable biomarkers. We advocate awareness and inclusion of the differentiation of injury type and ICP elevation in further studies with brain injury biomarkers.

Acute diagnostic biomarkers for spinal cord injury: review of the literature and preliminary research report

OBJECTIVE

Many efforts have been made to create new diagnostic technologies for use in the diagnosis of central nervous system injury. However, there is still no consensus for the use of biomarkers in clinical acute spinal cord injury (SCI). The aims of this review are (1) to evaluate the current status of neurochemical biomarkers and (2) to discuss their potential acute diagnostic role in SCI by reviewing the literature.

METHODS

PubMed (http://www.ncbi.nlm.nih.gov/pubmed) was searched up to 2012 to identify publications concerning diagnostic biomarkers in SCI. To support more knowledge, we also checked secondary references in the primarily retrieved literature.

RESULTS

Neurofilaments, cleaved-Tau, microtubule-associated protein 2, myelin basic protein, neuron-specific enolase, S100β, and glial fibrillary acidic protein were identified as structural protein biomarkers in SCI by this review process. We could not find reports relating ubiquitin C-terminal hydrolase-L1 and α-II spectrin breakdown products, which are widely researched in other central nervous system injuries. Therefore, we present our preliminary data relating to these two biomarkers. Some of biomarkers showed promising results for SCI diagnosis and outcome prediction; however, there were unresolved issues relating to accuracy and their accessibility.

CONCLUSION

Currently, there still are not many reports focused on diagnostic biomarkers in SCI. This fact warranted the need for greater efforts to innovate sensitive and reliable biomarkers for SCI.

Use of biomarkers for diagnosis and management of traumatic brain injury patients

BACKGROUND

Advances in the understanding of human biochemistry and physiology have provided insight into new pathways by which we can understand traumatic brain injury (TBI). Increased sophistication of laboratory techniques and developments in the field of proteomics has led to the discovery and rapid detection of new biomarkers not previously available.

OBJECTIVE

To review recent advances in biomarker research for traumatic brain injury, describe the features of the ideal biomarker and to explore the potential role of these biomarkers in improving clinical management of brain injured patients.

METHODS

Through a literature review of recent research on TBI biomarkers and through experience with TBI research, important elements of biomarker development are described together with potential applications to patient care.

CONCLUSIONS

TBI biomarkers could have a significant impact on patient care by assisting in the diagnosis, risk stratification and management of TBI. Biomarkers could provide major opportunities for the conduct of clinical research, including confirmation of injury mechanism(s) and drug target identification. Continuing studies by the authors' group are now being conducted to elucidate more fully the relationships between new biomarkers and severity of injury and clinical outcomes in all severities of TBI patients.

Tau proteins in serum predict neurological outcome after hypoxic brain injury from cardiac arrest: results of a pilot study

OBJECTIVE

To conduct a pilot study to evaluate the prognostic potential of serum tau protein measurements to predict neurological outcome 6 months following resuscitation from cardiac arrest.

METHODS

In this retrospective observational study, we employed a new ultra sensitive digital immunoassay technology to examine serial serum samples from 25 cardiac arrest patients to examine tau release into serum as a result of brain hypoxia, and probe for its significance predicting six-month neurological outcome. Serial blood samples were obtained from resuscitated cardiac arrest survivors during their first five days in an intensive care unit, and serum total tau was measured. Cerebral function assessments were made using Cerebral Performance Categorization (CPC) at discharge from the ICU and six months later. Tau data were analyzed in the context of 6-month CPC scores.

RESULTS

Tau elevations ranged from modest (<10 pg/mL) to very high (hundreds of pg/mL), and exhibited unexpected bi-modal kinetics in some patients. Early tau elevations appeared within 24h of cardiac arrest, and delayed elevations appeared after 24-48 h. In patients with delayed elevations, areas under the curves of tau concentration vs. hours since cardiac arrest were highly predictive of 6-month outcome (P<0.0005).

CONCLUSION

High-sensitivity serum tau measurements combined with an understanding of tau release kinetics could have utility for hypoxic brain injury assessment and prediction of cerebral function outcome.

Biomarkers, genetics, and risk factors for concussion

It is estimated that between 1.6 and 3.8 million concussions occur annually in the United States. Although frequently regarded as benign, concussions can lead to multiple different adverse outcomes, including prolonged postconcussive symptoms, chronic traumatic encephalopathy, cognitive impairment, early onset dementia, movement disorders, psychiatric disorders, motor neuron disease, and even death. Therefore it is important to identify individuals with concussion to provide appropriate medical care and minimize adverse outcomes. Furthermore, it is important to identify individuals who are predisposed to sustaining a concussion or to having an adverse outcome after concussion. This article will discuss the current research on serum biomarkers for concussion, genetic influence on concussion, risk factors associated with concussion predisposition and poor outcome, and practical suggestions for the application of this information in clinical practice.

Plasma tau protein in comatose patients after cardiac arrest treated with therapeutic hypothermia

BACKGROUND

Neurological outcome after cardiac arrest (CA) is difficult to predict in the acute phase. In this pilot study, we assessed blood levels of tau protein as a prognostic marker for the neurological outcome after 6 months in patients treated with hypothermia after resuscitation from CA.

METHODS

22 unconscious patients resuscitated after CA were treated with mild hypothermia (32-34°C) for 26 h. Blood samples were collected at 2, 6, 12, 24, 48, and 96 h after CA, and the concentration of tau protein was analyzed. Neurological outcome was assessed with the Glasgow-Pittsburgh cerebral performance category (CPC) scale at intensive care unit (ICU) discharge and after 6 months. The higher of the two CPC scores was used.

RESULTS

At ICU discharge, 21/22 patients were alive, of whom 10 had a good (CPC 1-2) outcome. After 6 months, 15/22 patients were alive, of whom 14 had a good outcome. Tau protein levels were higher among those with a poor outcome at 48 h and 96 h. At 96 h sampling, tau concentration predicted a poor outcome (CPC 3-5) with a sensitivity of 71% and a specificity of 93%.

CONCLUSIONS

Although in a pilot study, a late increase in plasma tau protein seems to be associated with a worse outcome after hypothermia treatment after CA, although more studies are needed.

Biomarkers associated with diffuse traumatic axonal injury: exploring pathogenesis, early diagnosis, and prognosis

BACKGROUND

Diffuse traumatic axonal injury (dTAI) is a significant pathologic feature of traumatic brain injury and is associated with substantial mortality and morbidity. It is still a challenge for clinicians to make an early diagnosis of dTAI and generate accurate prognosis and direct therapeutic decisions because most patients rapidly progress to coma after trauma and because specific neurologic symptoms and focal lesions detectable with current routine imaging techniques are absent. To address these issues, many investigations have sought to identify biomarkers of dTAI.

METHODS

This article is a review of the pertinent medical literature.

RESULTS

From the perspective of the pathophysiology of dTAI, we reviewed several biomarkers that are associated with structural damage and biochemical cascades in the secondary injury or repair response to traumatic brain injury. Although some biomarkers are not specific to dTAI, they are nevertheless useful in elucidating its pathogenesis, making early diagnosis possible, predicting outcomes, and providing candidate targets for novel therapeutic strategies.

CONCLUSIONS

The availability of biomarker data, clinical case histories, and radiologic information can improve our current ability to diagnose and monitor pathogenic conditions and predict outcomes in patients with dTAI.

The relation between delivery type and tau protein levels in cord blood

BACKGROUND

The perinatal morbidity risk is higher in operative deliveries than normal vaginal deliveries. 'Tau protein' is a cytoskeletal component that is predominantly expressed in axons of neurons. The aim of this study was to investigate whether delivery type, particularly the forceps application, had any effect on cord blood tau levels.

METHODS

Ninety babies born in the Division of Maternal-Fetal Medicine of Ankara Etlik Maternity and Women's Health Teaching Hospital, Ankara, Turkey were involved in the study. The babies were divided into three groups according to delivery type: Group 1: normal vaginal delivery (NVD); Group 2: caesarean section; Group 3: forceps application. Cord blood samples were drawn from umbilical veins of the babies soon after the birth.

RESULTS

The cord blood tau protein levels in the caesarean section group (79 pg/mL [45-223]) were found to be significantly lower than those of NVD (135 pg/mL [44-627]) and forceps (175 pg/mL [17-418]) groups (P = 0.001 and P < 0.001, respectively).

CONCLUSION

We have shown that forceps applications uncomplicated with perinatal asphyxia did not affect the cord blood tau protein level significantly. Tau levels in caesarean section group were significantly lower than the other two groups. Caesarean section in this manner might be considered especially in conditions of risk of perinatal asphyxia to avoid hypoxia.

Ubiquitin C-terminal hydrolase-L1 as a biomarker for ischemic and traumatic brain injury in rats

Ubiquitin C-terminal hydrolase-L1 (UCH-L1), also called neuronal-specific protein gene product 9.5, is a highly abundant protein in the neuronal cell body and has been identified as a possible biomarker on the basis of a recent proteomic study. In this study, we examined whether UCH-L1 was significantly elevated in cerebrospinal fluid (CSF) following controlled cortical impact (CCI) and middle cerebral artery occlusion (MCAO; model of ischemic stroke) in rats. Quantitative immunoblots of rat CSF revealed a dramatic elevation of UCH-L1 protein 48 h after severe CCI and as early as 6 h after mild (30 min) and severe (2 h) MCAO. A sandwich enzyme-linked immunosorbent assay constructed to measure UCH-L1 sensitively and quantitatively showed that CSF UCH-L1 levels were significantly elevated as early as 2 h and up to 48 h after CCI. Similarly, UCH-L1 levels were also significantly elevated in CSF from 6 to 72 h after 30 min of MCAO and from 6 to 120 h after 2 h of MCAO. These data are comparable to the profile of the calpain-produced alphaII-spectrin breakdown product of 145 kDa biomarker. Importantly, serum UCH-L1 biomarker levels were also significantly elevated after CCI. Similarly, serum UCH-L1 levels in the 2-h MCAO group were significantly higher than those in the 30-min group. Taken together, these data from two rat models of acute brain injury strongly suggest that UCH-L1 is a candidate brain injury biomarker detectable in biofluid compartments (CSF and serum).

Relationship between injury severity and serum tau protein levels in traumatic brain injured rats

BACKGROUND

Although serum tau protein levels increase following TBI, the time course is unknown. The aim of the present study was to determine whether serum tau protein levels increased in both a severity-dependent and time-dependent manner in an experimental model of rat traumatic brain injury (TBI).

METHODS

A total of 24 Sprague-Dawley rats were subjected to varying grades of TBI using a contusion injury model on the right parietal cortex. Enzyme-linked Immunoabsorbent Assay (ELISA) analysis for serum was performed at 15 min pre-injury, 1, 6, 24, 48, and 168 h post-injury. Immunoblotting for serum tau protein, neurological evaluation and histological observation were also performed.

RESULTS

Tau protein levels rapidly increased after 1 h in both mild and severe TBI groups (p<0.001), and declined after 6 h. In the sham-operated group, tau protein levels did not change significantly after TBI. Tau protein levels were severity-dependent at 1 and 6 h after TBI. The levels were higher in the severe TBI group than in the mild TBI group at 1 h (p<0.001) and 6 h (p<0.001).

CONCLUSIONS

Serum tau protein levels were severity-dependent and time-dependent at 1 and 6 h after TBI. However, the serum tau protein may not be a useful marker 24 h after TBI.

Tau as a biomarker of neurodegenerative diseases

The microtubule-associated protein Tau is mainly expressed in neurons of the CNS and is crucial in axonal maintenance and axonal transport. The rationale for Tau as a biomarker of neurodegenerative diseases is that it is a major component of abnormal intraneuronal aggregates observed in numerous tauopathies, including Alzheimer's disease. The molecular diversity of Tau is very useful when analyzing it in the brain or in the peripheral fluids. Immunohistochemical and biochemical characterization of Tau aggregates in the brain allows the postmortem classification and differential diagnosis of tauopathies. As peripheral biomarkers of Alzheimer's disease in the cerebrospinal fluid, Tau proteins are now validated for diagnosis and predictive purposes. For the future, the detailed characterization of Tau in the brain and in peripheral fluids will lead to novel promising biomarkers for differential diagnosis of dementia and monitoring of therapeutics.

Update on protein biomarkers in traumatic brain injury with emphasis on clinical use in adults and pediatrics

PURPOSE

This review summarizes protein biomarkers in mild and severe traumatic brain injury in adults and children and presents a strategy for conducting rationally designed clinical studies on biomarkers in head trauma.

METHODS

We performed an electronic search of the National Library of Medicine's MEDLINE and Biomedical Library of University of Pennsylvania database in March 2008 using a search heading of traumatic head injury and protein biomarkers. The search was focused especially on protein degradation products (spectrin breakdown product, c-tau, amyloid-beta(1-42)) in the last 10 years, but recent data on "classical" markers (S-100B, neuron-specific enolase, etc.) were also examined.

RESULTS

We identified 85 articles focusing on clinical use of biomarkers; 58 articles were prospective cohort studies with injury and/or outcome assessment.

CONCLUSIONS

We conclude that only S-100B in severe traumatic brain injury has consistently demonstrated the ability to predict injury and outcome in adults. The number of studies with protein degradation products is insufficient especially in the pediatric care. Cohort studies with well-defined end points and further neuroproteomic search for biomarkers in mild injury should be triggered. After critically reviewing the study designs, we found that large homogenous patient populations, consistent injury, and outcome measures prospectively determined cutoff values, and a combined use of different predictors should be considered in future studies.

Biomarkers in the clinical diagnosis and management of traumatic brain injury

Traumatic brain injury (TBI) is the leading cause of death and disability among young adults. Numerous safety improvements in the workplace, the addition of airbags to vehicles, and the enforcement of speed limits have all helped to reduce the incidence and severity of head trauma. While improvements in emergency response times and acute care have increased TBI survivability, this has heightened the necessity for developing reliable methods to identify patients at risk of developing secondary pathologies. At present, the primary clinical indicators for the presence of brain injury are the Glasgow Coma Scale (GCS), pupil reactivity, and head computed tomography (CT). While these indices have proven useful for stratifying the magnitude and extent of brain damage, they have limited utility for predicting adverse secondary events or detecting subtle damage. Biomarkers, reflecting a biological response to injury or disease, have proven useful for the diagnosis of many pathological conditions including cancer, heart failure, infection, and genetic disorders. For TBI, several proteins synthesized in astroglial cells or neurons have been proposed as potential biomarkers. These proteins include the BB isozyme of creatine kinase (CK-BB, predominant in brain), glial fibrilary acidic protein (GFAP), myelin basic protein (MBP), neuron-specific enolase (NSE), and S100B.The presence of these biomarkers in the cerebrospinal fluid and serum of patients with moderate-to-severe TBI, and their correlation with outcome, suggest that they may have utility as surrogate markers in clinical trials. In addition, many of these markers have been found to be sensitive indicators of injury, and therefore may have the potential to diagnose persons with mild TBI. In addition to biomarkers that correlate with long-term outcome, a few studies have identified prognostic biomarkers for secondary injury that may be useful in individualizing patient management.

Tau proteins in serum predict outcome after severe traumatic brain injury

BACKGROUND

The identification of reliable outcome predictors after traumatic brain injury (TBI) is crucial. The objective of our study was to investigate the role of tau protein as a serum marker of TBI.

METHODS

Thirty-four patients with severe TBI (Glasgow Coma Scale [GCS] score at admission <or= 8) were considered. The tau protein level in the blood samples obtained at the time of admission was measured. The outcome was assessed by using the Glasgow Outcome Scale (GOS) at 6 mo post-injury. Demographic, clinical, and laboratory variables were analyzed to study their effect on the outcome.

RESULTS

tau Protein levels were higher in the poor outcome group (436.2 +/- 473.6 pg/mL) than in the good outcome group (51.6 +/- 81.5 pg/mL) (P < 0.0001). Univariate analyses demonstrated that poor outcome was significantly associated with a poor GCS score (P = 0.001), higher serum tau protein levels (P < 0.001), abnormal pupil light reflex (P = 0.013), and basal cistern compression on computed tomogram (CT) (P = 0.026). Multivariate analyses revealed that a poor GCS score (P = 0.049) and higher serum tau protein levels (P = 0.043) were independent prognostic factors for poor outcome. The receiver-operating characteristic (ROC) curve demonstrated that a tau protein level >or= 114.5 pg/mL yielded 88% sensitivity and 94% specificity for predicting a poor outcome.

CONCLUSIONS

These results suggest that in addition to GCS; serum tau protein levels may serve as indicators for the prediction of outcome following severe TBI. However; it should be viewed with caution because of the small sample size and wide standard deviations.

The phosphorylated axonal form of the neurofilament subunit NF-H (pNF-H) as a blood biomarker of traumatic brain injury

The detection of neuron-specific proteins in blood might allow quantification of the degree of neuropathology in experimental and clinical contexts. We have been studying a novel blood biomarker of axonal injury, the heavily phosphorylated axonal form of the high molecular weight neurofilament subunit NF-H (pNF-H). We hypothesized that this protein would be released from damaged and degenerating neurons following experimental traumatic brain injury (TBI) in amounts large enough to allow its detection in blood and that the levels detected would reflect the degree of injury severity. An enzyme-linked immunosorbent assay (ELISA) capture assay capable of detecting nanogram amounts of pNF-H was used to test blood of rats subjected to experimental TBI using a controlled cortical impact (CCI) device. Animals were subjected to a mild (1.0 mm), moderate (1.5 mm), or severe (2.0 mm) cortical contusion, and blood samples were taken at defined times post-injury. The assay detected the presence of pNF-H as early as 6 h post-injury; levels peaked at 24-48 h, and then slowly decreased to baseline over several days post-injury. No signal above baseline was detectable in control animals. Analysis of variance (ANOVA) showed a significant effect of lesion severity, and post hoc analysis revealed that animals given a moderate and severe contusion showed higher levels of blood pNF-H than controls. In addition, the peak levels of pNF-H detected at both 24 and 48 h post-injury correlated with the degree of injury as determined by volumetric analysis of spared cortical tissue. Relative amounts of pNF-H were also determined in different areas of the central nervous system (CNS) and were found to be highest in regions containing large-diameter axons, including spinal cord and brainstem, and lowest in the cerebral cortex and hippocampus. These findings suggest that the measurement of blood levels of pNF-H is a convenient method for assessing neuropathology following TBI.