NEURON-SPECIFIC-ENOLASE IS INCREASED IN PLASMA AFTER HEMORRHAGIC SHOCK AND AFTER BILATERAL FEMUR FRACTURE WITHOUT TRAUMATIC BRAIN INJURY IN THE RAT

Neurofilament Light Chain Protein Is a Predictive Biomarker for Stroke After Surgical Repair for Acute Type A Aortic Dissection

Background: Although great progress has been made in surgery and perioperative care, stroke is still a fatal complication of acute type A aortic dissection (ATAAD). Serum biomarkers may help assess brain damage and predict patient's prognosis. Methods: From March, 2019 to January, 2020, a total of 88 patients underwent surgical treatment at the Department of Cardiovascular Surgery of Beijing Anzhen Hospital, China, and were enrolled in this study. Patients were divided into two groups according to whether they had suffered a stroke after the operation. Blood samples were collected at 8 time points within 3 days after surgery to determine the level of S100β, neuron-specific enolase (NSE) and neurofilament light chain protein (NFL). Receiver operating characteristic curves (ROC) were established to explore the biomarker predictive value in stroke. The area under the curve (AUC) was used to quantify the ROC curve. Results: The patient average age was 48.1 ± 11.0 years old and 70 (79.6%) patients were male. Fifteen (17.0%) patients suffered stroke after surgery. The NFL levels of patients in the stroke group at 12 and 24 h after surgery were significantly higher than those in the non-stroke group (all P < 0.001). However, the NSE and S100β levels did not differ significantly at any time point between the two groups. The predictive value of NFL was the highest at 12 and 24 h after surgery, and the AUC was 0.834 (95% CI, 0.723-0.951, P < 0.001) and 0.748 (95% CI, 0.603-0.894, P = 0.004), respectively. Its sensitivity and specificity at 12 h were 86.7 and 71.6%, respectively. The NFL cutoff value for the diagnosis of stroke at 12 h after surgery was 16.042 ng/ml. Conclusions: This study suggests that NFL is an early and sensitive serum marker for predicting post-operative neurological prognosis of ATAAD patients. Further studies, including large-scale prospective clinical trials, are necessary to test whether the NFL can be used as a biomarker for clinical decision-making.

Serum NSE and S100B protein levels for evaluating the impaired consciousness in patients with acute carbon monoxide poisoning

The aim of this study was to investigate the associations between the levels of neuron-specific enolase (NSE) and S100B protein and coma duration, and evaluate the optimal cut-off values for prediction coma duration ≥ 72 hours in patients with acute carbon monoxide poisoning (ACOP).A total of 60 patients with ACOP were divided into 3 following groups according to their status of consciousness and coma duration at admission: Awake group [Glasgow Coma Scale score (GCS score) ≥ 13 points], Coma < 72 hours group (GCS score < 13 points and coma duration < 72 h), and Coma ≥ 72 hours group (GCS score < 13 points and coma duration ≥ 72 h). The levels of serum NSE and S100B protein were measured after admission.There were significant differences in GCS score, carbon monoxide (CO) exposure time, NSE, and S100B levels between the Coma ≥ 72 h group and the Awake group, and between the Coma < 72 h group and the Awake group. Significant differences in GCS score, NSE, and S100B levels were also found between Coma ≥ 72 h group and Coma < 72 h group. Correlation analysis showed that NSE and S100B were positively correlated (rs = 0.590, P < .01); NSE and S100B were negatively correlated with GCS score (rs = -0.583, rs = -0.590, respectively, both P < .01). The areas under the curve (AUCs) of NSE, S100B, and GCS score to predict the coma duration ≥ 72 hours were 0.754, 0.791, and 0.785, respectively. Pairwise comparisons did not show differences among the 3 groups (all P > .05). The sensitivity and specificity of NSE prediction with a cut-off value of 13 μg/L were 80% and 64%, respectively, and those of S100B prediction with a cut-off value of 0.43 μg/L were 70% and 88%, respectively.The NSE and S100B protein levels were significantly correlated with the degree of impaired consciousness and had the same clinical value in predicting coma duration of ≥ 72 hours in patients with ACOP.

Cerebral Alterations Following Experimental Multiple Trauma and Hemorrhagic Shock

Multiple trauma (MT) associated with hemorrhagic shock (HS) might lead to cerebral hypoperfusion and brain damage. We investigated cerebral alterations using a new porcine MT/HS model without traumatic brain injury (TBI) and assessed the neuroprotective properties of mild therapeutic hypothermia. Male pigs underwent standardized MT with HS (45% or 50% loss of blood volume) and resuscitation after 90/120 min (T90/T120). In additional groups (TH90/TH120) mild hypothermia (33°C) was induced following resuscitation. Normothermic or hypothermic sham animals served as controls. Intracranial pressure, cerebral perfusion pressure (CPP), and cerebral oxygenation (PtiO2) were recorded up to 48.5 h. Serum protein S-100B and neuron-specific enolase (NSE) were measured by ELISA. Cerebral inflammation was quantified on hematoxylin and eosin -stained brain slices; Iba1, S100, and inducible nitric oxide synthase (iNOS) expression was assessed using immunohistochemistry. Directly after MT/HS, CPP and PtiO2 were significantly lower in T90/T120 groups compared with sham. After resuscitation both parameters showed a gradual recovery. Serum protein S-100B and NSE increased temporarily as a result of MT/HS in T90 and T90/T120 groups, respectively. Cerebral inflammation was found in all groups. Iba1-staining showed significant microgliosis in T90 and T120 animals. iNOS-staining indicated a M1 polarization. Mild hypothermia reduced cerebral inflammation in the TH90 group, but resulted in increased iNOS activation. In this porcine long-term model, we did not find evidence of gross cerebral damage when resuscitation was initiated within 120 min after MT/HS without TBI. However, trauma-related microglia activation and M1 microglia polarization might be a consequence of temporary hypoxia/ischemia and further research is warranted to detail underlying mechanisms. Interestingly, mild hypothermia did not exhibit neuroprotective properties when initiated in a delayed fashion.

Non-Coding RNAs to Aid in Neurological Prognosis after Cardiac Arrest

Cardiovascular disease in general, and sudden cardiac death in particular, have an enormous socio-economic burden worldwide. Despite significant efforts to improve cardiopulmonary resuscitation, survival rates remain low. Moreover, patients who survive to hospital discharge have a high risk of developing severe physical or neurological symptoms. Being able to predict outcomes after resuscitation from cardiac arrest would make it possible to tailor healthcare approaches, thereby maximising efforts for those who would mostly benefit from aggressive therapy. However, the identification of patients at risk of poor recovery after cardiac arrest is still a challenging task which could be facilitated by novel biomarkers. Recent investigations have recognised the potential of non-coding RNAs to aid in outcome prediction after cardiac arrest. In this review, we summarize recent discoveries and propose a handful of novel perspectives for the use of non-coding RNAs to predict outcome after cardiac arrest, discussing their use for precision medicine.

Unbiased Proteomic Approach Identifies Unique and Coincidental Plasma Biomarkers in Repetitive mTBI and AD Pathogenesis

The relationship between repetitive mild traumatic brain injury (r-mTBI) and Alzheimer's disease (AD) is well-recognized. However, the precise nature of how r-mTBI leads to or precipitates AD pathogenesis is currently not understood. Plasma biomarkers potentially provide non-invasive tools for detecting neurological changes in the brain, and can reveal overlaps between long-term consequences of r-mTBI and AD. In this study we address this by generating time-dependent molecular profiles of response to r-mTBI and AD pathogenesis in mouse models using unbiased proteomic analyses. To model AD, we used the well-validated hTau and PSAPP(APP/PS1) mouse models that develop age-related tau and amyloid pathological features, respectively, and our well-established model of r-mTBI in C57BL/6 mice. Plasma were collected at different ages (3, 9, and 15 months-old for hTau and PSAPP mice), encompassing pre-, peri- and post-"onset" of the cognitive and neuropathological phenotypes, or at different timepoints after r-mTBI (24 h, 3, 6, 9, and 12 months post-injury). Liquid chromatography/mass spectrometry (LC-MS) approaches coupled with Tandem Mass Tag labeling technology were applied to develop molecular profiles of protein species that were significantly differentially expressed as a consequence of mTBI or AD. Mixed model ANOVA after Benjamini-Hochberg correction, and a stringent cut-off identified 31 proteins significantly changing in r-mTBI groups over time and, when compared with changes over time in sham mice, 13 of these were unique to the injured mice. The canonical pathways predicted to be modulated by these changes were LXR/RXR activation, production of nitric oxide and reactive oxygen species and complement systems. We identified 18 proteins significantly changing in PSAPP mice and 19 proteins in hTau mice compared to their wild-type littermates with aging. Six proteins were found to be significantly regulated in all three models, i.e., r-mTBI, hTau, and PSAPP mice compared to their controls. The top canonical pathways coincidently changing in all three models were LXR/RXR activation, and production of nitric oxide and reactive oxygen species. This work suggests potential biomarkers for TBI and AD pathogenesis and for the overlap between these two, and warrant targeted investigation in human populations. Data are available via ProteomeXchange with identifier PXD010664.

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.

Biomarkers

Biomarkers are key tools and can provide crucial information on the complex cascade of events and molecular mechanisms underlying traumatic brain injury (TBI) pathophysiology. Obtaining a profile of distinct classes of biomarkers reflecting core pathologic mechanisms could enable us to identify and characterize the initial injury and the secondary pathologic cascades. Thus, they represent a logical adjunct to improve diagnosis, track progression and activity, guide molecularly targeted therapy, and monitor therapeutic response in TBI. Accordingly, great effort has been put into the identification of novel biomarkers in the past 25 years. However, the role of brain injury markers in clinical practice has been long debated, due to inconsistent regulatory standards and lack of reliable evidence of analytical validity and clinical utility. We present a comprehensive overview of the markers currently available while characterizing their potential role and applications in diagnosis, monitoring, drug discovery, and clinical trials in TBI. In reviewing these concepts, we discuss the recent inclusion of brain damage biomarkers in the diagnostic guidelines and provide perspectives on the validation of such markers for their use in the clinic.

Preliminary findings on biomarker levels from extracerebral sources in patients undergoing trauma surgery: Potential implications for TBI outcome studies

BACKGROUND

Despite several experimental studies on the role of S100B and NSE in fractures, no studies on the influence of surgery on the biomarker serum levels have been performed yet.

METHODS

The serum levels of S100B and NSE were analysed in patients with fractures that were located in the spine (group 1, n = 35) or in the lower extremity (group 2, n = 32) pre- and post-operatively.

RESULTS

The mean S100B serum level showed a significant increase (p = 0.04) post-surgery in the patients of group 1. In patients undergoing acute surgery (< 24 hours) the mean S100B serum level was 0.23 ± 0.22 μg L(-1) pre-operatively and 1.24 ± 1.38 μg L(-1) post-operatively. Likewise, the mean S100B serum level significantly increased in group 2 after surgery (p < 0.0001). In this group patients undergoing acute surgery showed a mean S100B serum level of 0.23 ± 0.14 μg L(-1) and 1.11 ± 0.73 μg L(-1) pre- and post-operatively.

CONCLUSION

This study demonstrates significant alterations of the biomarker S100B serum levels in patients undergoing surgery. Higher S100B serum levels were found within 24 hours and might be related to the acute fracture. The NSE serum levels were unchanged and this biomarker may offer the probability to serve as a future outcome predictor in studies with patients with traumatic brain injury and additional extracerebral injuries.

Blood biomarkers for brain injury: What are we measuring?

Accurate diagnosis for mild traumatic brain injury (mTBI) remains challenging, as prognosis and return-to-play/work decisions are based largely on patient reports. Numerous investigations have identified and characterized cellular factors in the blood as potential biomarkers for TBI, in the hope that these factors may be used to gauge the severity of brain injury. None of these potential biomarkers have advanced to use in the clinical setting. Some of the most extensively studied blood biomarkers for TBI include S100β, neuron-specific enolase, glial fibrillary acidic protein, and Tau. Understanding the biological function of each of these factors may be imperative to achieve progress in the field. We address the basic question: what are we measuring? This review will discuss blood biomarkers in terms of cellular origin, normal and pathological function, and possible reasons for increased blood levels. Considerations in the selection, evaluation, and validation of potential biomarkers will also be addressed, along with mechanisms that allow brain-derived proteins to enter the bloodstream after TBI. Lastly, we will highlight perspectives and implications for repetitive neurotrauma in the field of blood biomarkers for brain injury.

Current status of fluid biomarkers in mild traumatic brain injury

Mild traumatic brain injury (mTBI) affects millions of people annually and is difficult to diagnose. Mild injury is insensitive to conventional imaging techniques and diagnoses are often made using subjective criteria such as self-reported symptoms. Many people who sustain a mTBI develop persistent post-concussive symptoms. Athletes and military personnel are at great risk for repeat injury which can result in second impact syndrome or chronic traumatic encephalopathy. An objective and quantifiable measure, such as a serum biomarker, is needed to aid in mTBI diagnosis, prognosis, return to play/duty assessments, and would further elucidate mTBI pathophysiology. The majority of TBI biomarker research focuses on severe TBI with few studies specific to mild injury. Most studies use a hypothesis-driven approach, screening biofluids for markers known to be associated with TBI pathophysiology. This approach has yielded limited success in identifying markers that can be used clinically, additional candidate biomarkers are needed. Innovative and unbiased methods such as proteomics, microRNA arrays, urinary screens, autoantibody identification and phage display would complement more traditional approaches to aid in the discovery of novel mTBI biomarkers.

Shoulder surgery in the beach chair position is associated with diminished cerebral autoregulation but no differences in postoperative cognition or brain injury biomarker levels compared with supine positioning: the anesthesia patient safety foundation beach chair study

BACKGROUND

Although controversial, failing to consider the gravitational effects of head elevation on cerebral perfusion is speculated to increase susceptibility to rare, but devastating, neurologic complications after shoulder surgery in the beach chair position (BCP). We hypothesized that patients in the BCP have diminished cerebral blood flow autoregulation than those who undergo surgery in the lateral decubitus position (LDP). A secondary aim was to examine whether there is a relationship between patient positioning during surgery and postoperative cognition or serum brain injury biomarker levels.

METHODS

Patients undergoing shoulder surgery in the BCP (n = 109) or LDP (n = 109) had mean arterial blood pressure (MAP) and regional cerebral oxygen saturation (rScO2) monitored with near-infrared spectroscopy. A continuous, moving Pearson correlation coefficient was calculated between MAP and rScO2, generating the variable cerebral oximetry index (COx). When MAP is in the autoregulated range, COx approaches zero because there is no correlation between cerebral blood flow and arterial blood pressure. In contrast, when MAP is below the limit of autoregulation, COx is higher because there is a direct relationship between lower arterial blood pressure and lower cerebral blood flow. Thus, diminished autoregulation would be manifest as higher COx. Psychometric testing was performed before surgery and then 7 to 10 days and 4 to 6 weeks after surgery. A composite cognitive outcome was determined as the Z-score. Serum S100β, neuron-specific enolase, and glial fibrillary acidic protein were measured at baseline, after surgery, and on postoperative day 1.

RESULTS

After adjusting for age and history of hypertension, COx (P = 0.035) was higher and rScO2 lower (P < 0.0001) in the BCP group than in the LDP group. After adjusting for baseline composite cognitive outcome, there was no difference in Z-score 7 to 10 days (P = 0.530) or 4 to 6 weeks (P = 0.202) after surgery between the BCP and the LDP groups. There was no difference in serum biomarker levels between the 2 position groups

CONCLUSIONS

: Compared with patients in the LDP, patients undergoing shoulder surgery in the BCP are more likely to have higher COx indicating diminished cerebral autoregulation and lower rScO2. There were no differences in the composite cognitive outcome between the BCP and the LDP groups after surgery after accounting for baseline Z-score.

Neuroantibody biomarkers: links and challenges in environmental neurodegeneration and autoimmunity

The majority of neurodegenerative (ND) and autoimmune diseases (AID) remain idiopathic. The contribution of environmental chemicals to the development of these disorders has become of great interest in recent years. A convergence of mechanism between of ND and AID development has also emerged. In the case of ND, including neurotoxicity, the focus of this review, work over the last two decade in the realm of biomarker development, indicates that the immune response provides a venue whereby humoral immunity, in the form of autoantibodies to nervous system specific proteins, or neuroantibodies (NAb), may provide, once validated, a sensitive high throughput surrogate biomarker of effect with the potential of predicting outcome in absence of overt neurotoxicity/neurodegeneration. In addition, NAb may prove to be a contributor to the progression of the nervous system pathology, as well as biomarker of stage and therapeutic efficacy. There is a compelling need for biomarkers of effect in light of the introduction of new chemicals, such as nanoengineered material, where potential neurotoxicity remains to be defined. Furthermore, the convergence of mechanisms associated with ND and AID draws attention to the neglected arena of angiogenesis in defining the link between environment, ND, and AID.

The challenge of mild traumatic brain injury: role of biochemical markers in diagnosis of brain damage

During the past decade there has been an increasing recognition of the incidence of mild traumatic brain injury (mTBI) and a better understanding of the subtle neurological and cognitive deficits that may result from it. A substantial, albeit suboptimal, effort has been made to define diagnostic criteria for mTBI and improve diagnostic accuracy. Thus, biomarkers that can accurately and objectively detect brain injury after mTBI and, ideally, aid in clinical management are needed. In this review, we discuss the current research on serum biomarkers for mTBI including their rationale and diagnostic performances. Sensitive and specific biomarkers reflecting brain injury can provide important information regarding TBI pathophysiology and serve as candidate markers for predicting abnormal computed tomography findings and/or the development of residual deficits in patients who sustain an mTBI. We also outline the roles of biomarkers in settings of specific interest including pediatric TBI, sports concussions and military injuries, and provide perspectives on the validation of such markers for use in the clinic. Finally, emerging proteomics-based strategies for identifying novel markers will be discussed.

Biomarkers as predictors of outcome after cardiac arrest

Cardiac arrest (CA) is a major health and economic problem. Management of patients resuscitated from CA is challenging for clinicians, and the mortality rate of those who achieve return of spontaneous circulation remains high. Hypoxic brain injury, cardiovascular abnormalities and systemic ischemia/reperfusion response characterize the so-called 'postcardiac arrest syndrome', which could lead to multiple organ failure and poor outcome after CA. The magnitude of these disorders differs in individual patients, mainly based on the cause and duration of CA and on the severity of the ischemic episode. Prognostication of outcome after CA is of importance because it could help physicians on triage decisions and readdress the overall management. A number of factors are thought to influence the prognosis of patients after CA, but due to the heterogeneity of CA population and scenarios no single factor has been identified as a reliable predictor of outcome and the timing and optimal approach to prognostication is still controversial. Biomarkers represent a growing area of interest in this field, as they may provide clinicians with early information on the severity of organ dysfunction to make a decision on clinical strategies and prognosticate outcome. In this article, the authors will focus on cardiac, neurological and inflammatory biomarkers as potential predictors of outcome after CA.

Serum biomarkers of neurologic injury in cardiac operations

Assessment of subtle neurocognitive decline after surgical procedures has been hampered by heterogeneous testing techniques and a lack of reproducibility. This review summarizes the sensitivity and specificity of biomarkers of neurologic injury to determine whether they can be applied in the postoperative period to accurately predict neurocognitive decline. Creatine kinase-brain type, neuron-specific enolase, and S100B can be released into serum during operations by extracranial sources. Glial fibrillary acidic protein is a sensitive marker, and there are extracranial sources that are antigenically different from the brain-derived form. Serum levels of tau protein after acute neurologic injury do not reliability correlate with incidence.

The usefulness of S100B, NSE, GFAP, NF-H, secretagogin and Hsp70 as a predictive biomarker of outcome in children with traumatic brain injury

BACKGROUND

Predicting the long-term outcome after traumatic brain injury (TBI) is an important component of treatment strategy. Despite dramatically improved emergency management of TBI and apparent clinical recovery, most patients with TBI still may have long-term central nervous system (CNS) impairment.

METHODS

Sixty-three patients with TBI were enrolled into the prospective study. Venous blood samples were taken at admission and every 24 h for a maximum of 6 consecutive days. Serum concentrations of the biomarkers S100B, neuron-specific enolase (NSE), GFAP, NF-H, secretagogin and Hsp70 were quantified immuno-luminometrically or by enzyme-linked immunosorbent assay. The outcome was evaluated 6 months after TBI using the Glasgow Outcome Scale (GOS) in all patients.

RESULTS

The S100B levels in patients with worse outcome (GOS 4 or death) were already significantly higher at D0 (p < 0.001; p = 0.002). NSE levels were significantly higher in patients who died or had worse outcomes (p < 0.001; p = 0.003). Patients who had worse outcomes (GOS) or died had higher GFAP values (p < 0.001; p < 0.001), but their dynamics were similar over the same period. NF-H grew significantly faster in patients who had a worse GOS or died (p < 0.001; p = 0.001).

CONCLUSIONS

Although further prospective study is warranted, these findings suggest that levels of biomarkers correlate with mortality and may be useful as predictors of outcome in children with TBI.

Clinical applications of biomarkers in pediatric traumatic brain injury

INTRODUCTION

The diagnosis, treatment, and prediction of outcome in pediatric traumatic brain injury (TBI) present significant challenges to the treating clinician. Clinical and radiological tools for assessing injury severity and predicting outcome, in particular, lack sensitivity and specificity. In patients with mild TBI, often there is uncertainty about which patients should undergo radiological imaging and who is at risk for long term neurological sequelae. In severe TBI, often there is uncertainty about which patients will experience secondary insults and what the outcome for individual patients will be. In several other clinical specialties, biomarkers are used to diagnose disease, direct treatment, and prognosticate. However, an ideal biomarker for brain injury has not been found.

METHODS

In this review, we examine the various factors that must be taken into account in the search for a reliable biomarker in brain injury. We review the important studies that have investigated common biomarkers of structural brain injury, in particular S100B, neuron-specific enolase, myelin basic protein, and glial fibrillary acid protein.

DISCUSSION

The potential uses and limitations of these biomarkers in the context of TBI are discussed.

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.

Animal models for trauma research: what are the options?

Even if trauma patients initially avoid death after trauma (due to massive blood volume loss, primary severe brain injury), they are still at risk for multiple organ failure. Thus, it is crucial to elucidate the underlying pathophysiological mechanisms of trauma/hemorrhagic shock and the immune response involved. As of now, many hemorrhagic shock/trauma studies have used various types of animal models. Despite a large number of results from these efforts, some authors have argued that animal model results are difficult to translate directly into the clinical scenario. This review summarizes the advantages and the disadvantages of using animal models in trauma/hemorrhagic shock studies and discusses the relevance of various animal studies to the clinical scenario.

Glial fibrillary acidic protein is highly correlated with brain injury

BACKGROUND

Glial fibrillary acidic protein (GFAP) is an intermediate filament protein found in the cytoskeleton of astroglia. Recent work has indicated that GFAP may serve as a serum marker of traumatic brain injury (TBI) that is released after central nervous system cell damage.

METHODS

Serum from 51 critically injured trauma patients was prospectively collected on admission and on hospital day 2. All patients underwent an admission head computed tomography (CT) scan as a part of their clinical evaluation. Patients with facial fractures in the absence of documented TBI and patients with spinal cord injury were excluded. Demographic and outcome data were collected prospectively. Serum GFAP was measured in duplicate using enzyme-linked immunosorbent assay techniques.

RESULTS

Thirty-nine (76%) of the 51 patients had CT-documented TBI. The study cohort was 72.5% men with a mean age of 43 years and mean Injury Severity Score (ISS) of 30.2. There were no statistically significant demographic differences between the two groups. At admission day, the mean GFAP level in non-TBI patients was 0.07 pg/mL compared with 6.77 pg/mL in TBI patients (p = 0.002). On day 2 the mean GFAP level was 0.02 in non-TBI patients compared with 2.17 in TBI patients (p = 0.003). Using regression analysis to control for age, sex, and ISS, the Head Abbreviated Injury Scale was predictive of the level of GFAP on both days 1 and 2 (p values 0.006 and 0.026, respectively). Although GFAP levels were not predictive of increased hospital length of stay, intensive care unit length of stay, or ventilator days, high GFAP levels on hospital day 2 were predictive of mortality when controlling for age, sex, and ISS (odds ratio 1.45, p value 0.028). The area under the receiver operating characteristic curve for GFAP was 0.90 for day 1 and 0.88 for day 2. A GFAP cutoff point of 1 pg/mL yielded 100% specificity and 50% to 60% sensitivity for TBI.

CONCLUSIONS

GFAP is a serum marker of TBI, and persistent elevation on day 2 is predictive of increased mortality. Excellent specificity for CT-documented brain injury was found using a cutoff point of 1 pg/mL.

Biomarkers of primary and evolving damage in traumatic and ischemic brain injury: diagnosis, prognosis, probing mechanisms, and therapeutic decision making

PURPOSE OF REVIEW

Emerging data suggest that biomarkers of brain injury have potential utility as diagnostic, prognostic, and therapeutic adjuncts in the setting of traumatic and ischemic brain injury. Two approaches are being used, namely, assessing markers of structural damage and quantifying mediators of the cellular, biochemical, or molecular cascades in secondary injury or repair. Novel proteomic, multiplex, and lipidomic methods are also being applied.

RECENT FINDINGS

Biochemical markers of neuronal, glial, and axonal damage such as neuron-specific enolase, S100B, and myelin basic protein, respectively, are readily detectable in biological samples such as serum or cerebrospinal fluid and are being studied in patients with ischemic and traumatic brain injury. In addition, a number of studies have demonstrated that novel tools to assess simultaneously multiple biomarkers can provide unique insight such as details on specific molecular participants in cell death cascades, inflammation, or oxidative stress.

SUMMARY

Multifaceted cellular, biochemical, and molecular monitoring of proteins and lipids is logical as an adjunct to guiding therapies and improving outcomes in traumatic and ischemic brain injury and we appear to be on the verge of a breakthrough with the use of these markers as diagnostic, prognostic, and monitoring adjuncts, in neurointensive care.

S100B is not a reliable prognostic index in paediatric TBI

BACKGROUND

As far as paediatric traumatic brain injury is concerned, it is difficult to quantify the extent of the primary insult, to monitor secondary changes and to predict neurological outcomes by means of the currently used diagnostic tools: physical examination, Glasgow Coma Scale (GCS) score and computed tomography. For this reason, several papers focused on the use of biochemical markers (S100B, neuron-specific enolase) to detect and define the severity of brain damage and predict outcome after traumatic head injury or cardiac arrest.

OBJECTIVE

The aim of this paper is measuring the range of S100B serum concentrations in children affected by traumatic brain injury and describing the possible roles of this protein in the reaction to trauma.

METHODS

Fifteen children aged 1-15 years were included in the study. Traumatic brain injury severity was defined by paediatric GCS score as mild (9 patients), moderate (2 patients) or severe (4 patients). Blood samples for S100B serum measurement were taken at emergency department admission and after 48 h.

RESULTS

The serum S100B concentration was higher in the group of severe trauma patients, who scored the lowest on the GCS at admission, and among them, the highest values were reported by the children with concomitant peripheral lesions.

CONCLUSIONS

The role of S100B in paediatric traumatic brain injury has not been clarified yet, and the interpretation of its increase when the head trauma is associated with other injuries needs the understanding of the physiopathological mechanisms that rule its release in the systemic circulation. The levels of S100B in serum after a brain injury could be related to the mechanical discharge from a destroyed blood-brain barrier, or they could be due to the active expression by the brain, as a part of its involvement in the systemic inflammatory reaction. Early increase of this protein is not a reliable prognostic index of neurological outcome after pediatric traumatic brain injury, since even very elevated values are compatible with a complete neurological recovery.

SMALL-VOLUME FLUID RESUSCITATION WITH HYPERTONIC SALINE PREVENTS INFLAMMATION BUT NOT MORTALITY IN A RAT MODEL OF HEMORRHAGIC SHOCK

Hemorrhage remains a primary cause of death in civilian and military trauma. Permissive hypotensive resuscitation is a possible approach to reduce bleeding in patients until they can be stabilized in an appropriate hospital setting. Small-volume resuscitation with hypertonic saline (HS) is of particular interest because it allows one to modulate the inflammatory response to hemorrhage and trauma. Here, we tested the utility of permissive hypotensive resuscitation with hypertonic fluids in a rat model of hemorrhagic shock. Animals were subjected to massive hemorrhage [mean arterial pressure (MAP) = 30 - 35 mmHg for 2 h until decompensation] and partially resuscitated with a bolus dose of 4 mL/kg of 7.5% NaCl (HS), hypertonic hydroxyl ethyl starch (HHES; hydroxyl ethyl starch + 7.5% NaCl), or normal saline (NS) followed by additional infusion of Ringer solution to maintain MAP at 40 to 45 mmHg for 40 min (hypotensive state). Finally, animals were fully resuscitated with Ringer solution and the heparinized shed blood. Hypotensive resuscitation with NS caused a significant increase in plasma interleukin (IL)-1beta, IL-6, IL-2, interferon gamma (IFNgamma), IL-10, and granulocyte-macrophage colony stimulating factor (GM-CSF). This increase was blocked by treatment with HS. HHES treatment significantly reduced the increase of IL-1beta and IL-2 but not that of the other cytokines studied. Despite the strong effects of HS and HHES on cytokine production, both treatments had little effect on plasma lactate, base excess (BE), white blood cell (WBC) count, myeloperoxidase (MPO) content, and the wet/dry weight ratio of the lungs. Moreover, on day 7 after shock, the survival rate in rats treated with HS was markedly, but not significantly, lower than that of NS-treated animals (47% vs. 63%, respectively). In summary, hypotensive resuscitation with hypertonic fluids reduces the inflammatory response but not lung tissue damage or mortality after severe hemorrhagic shock.

Nonspecific increase of systemic neuron-specific enolase after trauma: clinical and experimental findings

The aim of this clinical and experimental study was to determine whether systemic neuron-specific enolase (NSE) is a useful early marker of traumatic brain injury (TBI) and whether NSE is affected by ischemia/reperfusion damage of abdominal organs. Our study included patients with and without TBI (verified by computerized tomography) admitted within 6 h after trauma and male Sprague-Dawley rats with ischemia and reperfusion of the abdominal organs liver, gut, or kidney. Thirty-eight study patients included 13 with isolated TBI and 18 patients with multiple trauma and TBI. Seven patients had multiple trauma but no TBI. Fifteen rats were anaesthetized and subjected to isolated ischemia of the liver, gut, or kidney (n = 5 each) for 1 h, followed by reperfusion for 3 h. In patients, NSE increased over 2-fold versus the upper normal limit (10 microg/L) within 6 h after trauma, regardless of whether TBI had occurred or not. In rats, NSE increased over 3-fold versus laboratory controls during ischemia of the liver and kidney (both P < 0.0005), but not of the gut. NSE increased over 2-fold after onset of reperfusion of the liver and kidney (both P < 0.05), but not of the gut and increased over 3-fold after 3 h of reperfusion of the liver, gut (both P < 0.005), and kidney (P < 0.0005). Our data show that systemic NSE increases to similar degrees with and without TBI. Therefore, NSE is not a useful early marker of TBI in multiple trauma.

Profound Hypothermia Protects Neurons and Astrocytes, and Preserves Cognitive Functions in a Swine Model of Lethal Hemorrhage1

BACKGROUND

Lethal injuries can be repaired under asanguineous hypothermic arrest (suspended animation) with excellent survival. This experiment was designed to test the impact of this strategy on neuronal and astroglial damage in a swine model of lethal hemorrhage. Furthermore, our goal was to correlate the histological changes in the brain with neurological outcome, and the levels of circulating brain specific markers.

MATERIALS AND METHODS

Uncontrolled hemorrhage was induced in 32 female swine (80-120 lbs) by creating an iliac artery and vein injury, followed 30 min later by laceration of the thoracic aorta. Through a thoracotomy approach, organ preservation fluid was infused into the aorta using a roller pump. Experimental groups included normothermic controls (no cooling, NC), and groups where hypothermia was induced at three different rates: 0.5 degrees C/min (slow, SC), 1 degrees C/min (medium, MC), or 2 degrees C/min (fast, FC). Profound hypothermia (core temperature of 10 degrees C) was maintained for 60 min for repair of vascular injuries, after which the animals were re-warmed (0.5 degrees C/min) and resuscitated on cardiopulmonary bypass (CPB). Circulating levels of neuron specific enolase (NSE) and S-100beta were serially measured as markers of damage to neurons and astrocytes, respectively. Light microscopy and quantitative immunohistochemical techniques were used to evaluate hippocampal CA1 area and caudate putamen for neuronal injury and astrogliosis (astrocyte hyperplasia/hypertrophy). Surviving animals were observed for 6 weeks and neurological status was documented on an objective scale, and cognitive functions were evaluated using a technique based upon the concept of operant conditioning.

RESULTS

Normothermic arrest resulted in clinical brain death in all of the animals. None of the surviving hypothermic animals displayed any neurological deficits or cognitive impairment. On histological examination, normothermic animals were found to have ischemic changes in the neurons and astrocytes (hypertrophy). In contrast, all of the hypothermic animals had histologically normal brains. The circulating levels of brain specific proteins did not correlate with the degree of brain damage. The changes in NSE levels were not statistically significant, whereas S-100beta increased in the circulation after CPB, largely independent of the temperature modulation.

CONCLUSIONS

Profound hypothermia can preserve viability of neurons and astrocytes during prolonged periods of cerebral hypoxia. This approach is associated with excellent cognitive and neurological outcome following severe shock. Circulating markers of central nervous system injury did not correlate with the actual degree of brain damage in this model.