Clinical significance of serum S100B levels in neurointensive care

Mechanobiological Modulation of In Vitro Astrocyte Reactivity Using Variable Gel Stiffness

After traumatic brain injury, the brain extracellular matrix undergoes structural rearrangement due to changes in matrix composition, activation of proteases, and deposition of chondroitin sulfate proteoglycans by reactive astrocytes to produce the glial scar. These changes lead to a softening of the tissue, where the stiffness of the contusion "core" and peripheral "pericontusional" regions becomes softer than that of healthy tissue. Pioneering mechanotransduction studies have shown that soft substrates upregulate intermediate filament proteins in reactive astrocytes; however, many other aspects of astrocyte biology remain unclear. Here, we developed a platform for the culture of cortical astrocytes using polyacrylamide (PA) gels of varying stiffness (measured in Pascal; Pa) to mimic injury-related regions in order to investigate the effects of tissue stiffness on astrocyte reactivity and morphology. Our results show that substrate stiffness influences astrocyte phenotype; soft 300 Pa substrates led to increased GFAP immunoreactivity, proliferation, and complexity of processes. Intermediate 800 Pa substrates increased Aggrecan+, Brevican+, and Neurocan+ astrocytes. The stiffest 1 kPa substrates led to astrocytes with basal morphologies, similar to a physiological state. These results advance our understanding of astrocyte mechanotransduction processes and provide evidence of how substrates with engineered stiffness can mimic the injury microenvironment.

Time-Dependent Changes in the Biofluid Levels of Neural Injury Markers in Severe Traumatic Brain Injury Patients-Cerebrospinal Fluid and Cerebral Microdialysates: A Longitudinal Prospective Pilot Study

Monitoring protein biomarker levels in the cerebrospinal fluid (CSF) can help assess injury severity and outcome after traumatic brain injury (TBI). Determining injury-induced changes in the proteome of brain extracellular fluid (bECF) can more closely reflect changes in the brain parenchyma, but bECF is not routinely available. The aim of this pilot study was to compare time-dependent changes of S100 calcium-binding protein B (S100B), neuron-specific enolase (NSE), total Tau, and phosphorylated Tau (p-Tau) levels in matching CSF and bECF samples collected at 1, 3, and 5 days post-injury from severe TBI patients (n = 7; GCS 3-8) using microcapillary-based western analysis. We found that time-dependent changes in CSF and bECF levels were most pronounced for S100B and NSE, but there was substantial patient-to-patient variability. Importantly, the temporal pattern of biomarker changes in CSF and bECF samples showed similar trends. We also detected two different immunoreactive forms of S100B in both CSF and bECF samples, but the contribution of the different immunoreactive forms to total immunoreactivity varied from patient to patient and time point to time point. Our study is limited, but it illustrates the value of both quantitative and qualitative analysis of protein biomarkers and the importance of serial sampling for biofluid analysis after severe TBI.

COMPARATIVE EVALUATION AND PROGNOSTIC UTILITY OF NEURONAL INJURY BIOMARKERS IN COVID-19 PATIENTS: A PROSPECTIVE STUDY

ABSTRACT

Background : COVID-19 disease severity markers include mostly molecules related to not only tissue perfusion, inflammation, and thrombosis, but also biomarkers of neural injury. Clinical and basic research has demonstrated that SARS-COV-2 affects the central nervous system. The aims of the present study were to investigate the role of neural injury biomarkers and to compare them with inflammatory markers in their predictive ability of mortality. Methods : We conducted a prospective observational study in critically ill patients with COVID-19 and in a cohort of patients with moderate/severe disease. S100b, neuron-specific enolase (NSE), and inflammatory markers, including soluble urokinase plasminogen activator receptor (suPAR), were measured on intensive care unit or ward admission, respectively. Statistical comparisons between patient groups were performed for all biomarkers under investigation. Correlations between different biomarkers were tested with Spearman correlation coefficient. Receiver operating characteristic curves were plotted using mortality as the classification variable and the biomarker levels on admission as the prognostic variables. Results : A total of 70 patients with COVID-19 were included in the final analysis. Of all studied biomarkers, s100b had the best predictive ability for death in the intensive care unit, with an area under the curve of 0.73 (0.61-0.83), P = 0.0003. S100b levels correlated with NSE, interleukin (IL)-8, and IL-10 (0.27 < rs < 0.37, P < 0.05), and tended to correlate with suPAR ( rs = 0.26, P = 0.05), but not with the vasopressor dose ( P = 0.62). Conclusion : Among the investigated biomarkers, s100b demonstrated the best predictive ability for death in COVID-19 patients. The overall biomarker profile of the patients implies direct involvement of the nervous system by the novel coronavirus.

GFAP and S100B: What You Always Wanted to Know and Never Dared to Ask

Traumatic brain injury (TBI) is a major global health issue, with outcomes spanning from intracranial bleeding, debilitating sequelae, and invalidity with consequences for individuals, families, and healthcare systems. Early diagnosis of TBI by testing peripheral fluids such as blood or saliva has been the focus of many research efforts, leading to FDA approval for a bench-top assay for blood GFAP and UCH-L1 and a plasma point-of-care test for GFAP. The biomarker S100B has been included in clinical guidelines for mTBI (mTBI) in Europe. Despite these successes, several unresolved issues have been recognized, including the robustness of prior data, the presence of biomarkers in tissues beyond the central nervous system, and the time course of biomarkers in peripheral body fluids. In this review article, we present some of these issues and provide a viewpoint derived from an analysis of existing literature. We focus on two astrocytic proteins, S100B and GFAP, the most commonly employed biomarkers used in mTBI. We also offer recommendations that may translate into a broader acceptance of these clinical tools.

Evidence of Brain Alterations in Noncerebral Falciparum Malaria

BACKGROUND

Cerebral malaria in adults is associated with brain hypoxic changes on magnetic resonance (MR) images and has a high fatality rate. Findings of neuroimaging studies suggest that brain involvement also occurs in patients with uncomplicated malaria (UM) or severe noncerebral malaria (SNCM) without coma, but such features were never rigorously characterized.

METHODS

Twenty patients with UM and 21 with SNCM underwent MR imaging on admission and 44-72 hours later, as well as plasma analysis. Apparent diffusion coefficient (ADC) maps were generated, with values from 5 healthy individuals serving as controls.

RESULTS

Patients with SNCM had a wide spectrum of cerebral ADC values, including both decreased and increased values compared with controls. Patients with low ADC values, indicating cytotoxic edema, showed hypoxic patterns similar to cerebral malaria despite the absence of deep coma. Conversely, high ADC values, indicative of mild vasogenic edema, were observed in both patients with SNCM and patients with UM. Brain involvement was confirmed by elevated circulating levels of S100B. Creatinine was negatively correlated with ADC in SNCM, suggesting an association between acute kidney injury and cytotoxic brain changes.

CONCLUSIONS

Brain involvement is common in adults with SNCM and a subgroup of hospitalized patients with UM, which warrants closer neurological follow-up. Increased creatinine in SNCM may render the brain more susceptible to cytotoxic edema.

Features of urine S100B and its ability to rule out intracranial hemorrhage in patients with head trauma: a prospective trial

Purpose

Traumatic brain injury causes morbidity and mortality worldwide. S100B is the most documented emergency brain biomarker and its urine-assay might be advantageous because of easier sampling. The primary aim was to evaluate urine S100B’s ability to rule out intracranial hemorrhage. Secondary aims included S100B temporal pattern for 48 h post-trauma and chemical properties of urine that affect urine S100B.

Methods

Patients with head trauma were sampled for serum and urine S100B. Patients who were admitted for intracranial hemorrhage were sampled for 48 h to assess S100B-level, renal function, urine-pH, etc.

Results

The negative predictive value of serum S100B was 97.0% [95% confidence interval (CI) 89.5–99.2%] and that of urine S100B was 89.1% (95% CI 85.5–91.9%). The specificity of serum S100B was 34.4% (95% CI 27.7–41.6%) and that of urine was 67.1% (95% CI 59.4–74.1%). Urine-pH correlated strongly with urine S100B during the first 6-h post-trauma. Trend-analysis of receiver operator characteristics of S100B in serum, urine the arithmetic difference between serum and urine S100B showed the largest area under the curve for arithmetic difference, which had a negative predictive value of 93.1% (95% CI 89.1–95.8%) and a specificity of 71.8% (95% CI 64.4–78.4%).

Conclusion

This study cannot support ruling out intracranial hemorrhage with urine S100B. Urine-pH might affect urine S100B and merits further studies. Serum and urine S100B have poor concordance and interchangeability. The arithmetic difference had a slightly better area under the curve and can be worth exploring in certain subgroups.

Clinical Use of the Calcium-Binding S100B Protein, a Biomarker for Head Injury

S100B is a calcium-binding protein most abundant in neuronal tissue. It is expressed in glial cells and Schwann cells and exerts both intra- and extracellular effects. Depending on the concentration, secreted S100B exerts either trophic or toxic effects. Its functions have been extensively studied but are still not fully understood. It can be measured in cerebrospinal fluid and in blood, and increased S100B level in blood can be seen after, e.g., traumatic brain injury, certain neurodegenerative disorders, and malignant melanoma. This chapter provides a short background of protein S100B, commercially available methods of analysis, and its clinical use, especially as a biomarker in minor head injury.

Serum levels of S100B from jugular bulb as a biomarker of poor prognosis in patients with severe acute brain injury

AIMS/BACKGROUND

To evaluate the correlation between protein S100B concentrations measured in the jugular bulb as well as at peripheral level and the prognostic usefulness of this marker.

METHODS

A prospective study of all patients admitted to the intensive care unit with acute brain damage was carried out. Peripheral and jugular bulb blood samples were collected upon admission and every 24h for three days. The endpoints were brain death diagnosis and the Glasgow Outcome Scale score after 6months.

RESULTS

A total of 83 patients were included. Jugular protein S100B levels were greater than systemic levels upon admission and also after 24 and 72h (mean difference>0). Jugular protein S100B levels showed acceptable precision in predicting brain death both upon admission [AUC 0.67 (95% CI 0.53-0.80)] and after 48h [AUC 0.73 (95% CI 0.57-0.89)]. Similar results were obtained regarding the capacity of jugular protein S100B levels upon admission to predict an unfavourable outcome (AUC 0.69 (95% CI 0.56-0.79)). The gradient upon admission (jugular-peripheral levels) showed its capacity to predict the development of brain death [AUC 0.74 (95% CI 0.62-0.86)] and together with the Glasgow Coma Scale constituted the independent factors associated with the development of brain death.

CONCLUSION

Regional protein S100B determinations are higher than systemic determinations, thus confirming the cerebral origin of protein S100B. The transcranial protein S100B gradient is correlated to the development of brain death.

Serial Sampling of Serum Protein Biomarkers for Monitoring Human Traumatic Brain Injury Dynamics: A Systematic Review

BACKGROUND

The proteins S100B, neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), and neurofilament light (NF-L) have been serially sampled in serum of patients suffering from traumatic brain injury (TBI) in order to assess injury severity and tissue fate. We review the current literature of serum level dynamics of these proteins following TBI and used the term "effective half-life" (t1/2) in order to describe the "fall" rate in serum.

MATERIALS AND METHODS

Through searches on EMBASE, Medline, and Scopus, we looked for articles where these proteins had been serially sampled in serum in human TBI. We excluded animal studies, studies with only one presented sample and studies without neuroradiological examinations.

RESULTS

Following screening (10,389 papers), n = 122 papers were included. The proteins S100B (n = 66) and NSE (n = 27) were the two most frequent biomarkers that were serially sampled. For S100B in severe TBI, a majority of studies indicate a t1/2 of about 24 h, even if very early sampling in these patients reveals rapid decreases (1-2 h) though possibly of non-cerebral origin. In contrast, the t1/2 for NSE is comparably longer, ranging from 48 to 72 h in severe TBI cases. The protein GFAP (n = 18) appears to have t1/2 of about 24-48 h in severe TBI. The protein UCH-L1 (n = 9) presents a t1/2 around 7 h in mild TBI and about 10 h in severe. Frequent sampling of these proteins revealed different trajectories with persisting high serum levels, or secondary peaks, in patients with unfavorable outcome or in patients developing secondary detrimental events. Finally, NF-L (n = 2) only increased in the few studies available, suggesting a serum availability of >10 days. To date, automated assays are available for S100B and NSE making them faster and more practical to use.

CONCLUSION

Serial sampling of brain-specific proteins in serum reveals different temporal trajectories that should be acknowledged. Proteins with shorter serum availability, like S100B, may be superior to proteins such as NF-L in detection of secondary harmful events when monitoring patients with TBI.

A review of the clinical utility of serum S100B protein levels in the assessment of traumatic brain injury

Background

In order to improve injury assessment of brain injuries, protein markers of pathophysiological processes and tissue fate have been introduced in the clinic. The most studied protein “biomarker” of cerebral damage in traumatic brain injury (TBI) is the protein S100B. The aim of this narrative review is to thoroughly analyze the properties and capabilities of this biomarker with focus on clinical utility in the assessment of patients suffering from TBI.

Results

S100B has successfully been implemented in the clinic regionally (1) to screen mild TBI patients evaluating the need to perform a head computerized tomography, (2) to predict outcome in moderate-to-severe TBI patients, (3) to detect secondary injury development in brain-injured patients and (4) to evaluate treatment efficacy. The potential opportunities and pitfalls of S100B in the different areas usually refer to its specificity and sensitivity to detect and assess intracranial injury.

Conclusion

Given some shortcomings that should be realized, S100B can be used as a versatile screening, monitoring and prediction tool in the management of TBI patients.

A review of the clinical utility of serum S100B protein levels in the assessment of traumatic brain injury

BACKGROUND

In order to improve injury assessment of brain injuries, protein markers of pathophysiological processes and tissue fate have been introduced in the clinic. The most studied protein "biomarker" of cerebral damage in traumatic brain injury (TBI) is the protein S100B. The aim of this narrative review is to thoroughly analyze the properties and capabilities of this biomarker with focus on clinical utility in the assessment of patients suffering from TBI.

RESULTS

S100B has successfully been implemented in the clinic regionally (1) to screen mild TBI patients evaluating the need to perform a head computerized tomography, (2) to predict outcome in moderate-to-severe TBI patients, (3) to detect secondary injury development in brain-injured patients and (4) to evaluate treatment efficacy. The potential opportunities and pitfalls of S100B in the different areas usually refer to its specificity and sensitivity to detect and assess intracranial injury.

CONCLUSION

Given some shortcomings that should be realized, S100B can be used as a versatile screening, monitoring and prediction tool in the management of TBI patients.

Biofluid Proteomics and Biomarkers in Traumatic Brain Injury

Traumatic brain injury (TBI) is an injury to the brain caused by an external mechanical force, affecting millions of people worldwide. The disease course and prognosis are often unpredictable, and it can be challenging to determine an early diagnosis in case of mild injury as well as to accurately phenotype the injury. There is currently no cure for TBI-drugs having failed repeatedly in clinical trials-but an intense effort has been put to identify effective neuroprotective treatment. The detection of novel biomarkers, to understand more of the disease mechanism, facilitates early diagnosis, predicts disease progression, and develops molecularly targeted therapies that would be of high clinical interest. Over the last decade, there has been an increasing effort and initiative toward finding TBI-specific biomarker candidates. One promising strategy has been to use state-of-the-art neuroproteomics approaches to assess clinical biofluids and compare the cerebrospinal fluid (CSF) and blood proteome between TBI and control patients or between different subgroups of TBI. In this chapter, we summarize and discuss the status of biofluid proteomics in TBI, with a particular focus on the latest findings.

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.

Role of Systems Biology in Brain Injury Biomarker Discovery: Neuroproteomics Application

Years of research in the field of neurotrauma have led to the concept of applying systems biology as a tool for biomarker discovery in traumatic brain injury (TBI). Biomarkers may lead to understanding mechanisms of injury and recovery in TBI and can be potential targets for wound healing, recovery, and increased survival with enhanced quality of life. The literature available on neurotrauma studies from both animal and clinical studies has provided rich insight on the molecular pathways and complex networks of TBI, elucidating the proteomics of this disease for the discovery of biomarkers. With such a plethora of information available, the data from the studies require databases with tools to analyze and infer new patterns and associations. The role of different systems biology tools and their use in biomarker discovery in TBI are discussed in this chapter.

Secondary peaks of S100B in serum relate to subsequent radiological pathology in traumatic brain injury

INTRODUCTION

Patients suffering from severe traumatic brain injury (TBI) often develop secondary brain lesions that may worsen outcome. S100B, a biomarker of brain damage, has been shown to increase in response to secondary cerebral deterioration. The aim of this study was to analyze the occurrence of secondary increases in serum levels of S100B and their relation to potential subsequent radiological pathology present on CT/MRI-scans.

METHODS

Retrospective study from a trauma level 1 hospital, neuro-intensive care unit. 250 patients suffering from TBI were included. Inclusion required a minimum of two radiological examinations and at least three serum samples of S100B, with at least one >48 h after trauma.

RESULTS

Secondary pathological findings on CT/MRI, present in 39 % (n = 98) of the patients, were highly correlated to secondary increases of ≥0.05 μg/L S100B (P < 0.0001, pseudo-R (2) 0.532). Significance remained also after adjusting for known important TBI predictors. In addition, secondary radiological findings were significantly correlated to outcome (Glasgow Outcome Score, GOS) in uni-(P < 0.0001, pseudo-R (2) 0.111) and multivariate analysis. The sensitivity and specificity of detecting later secondary radiological findings was investigated at three S100B cut-off levels: 0.05, 0.1, and 0.5 μg/L. A secondary increase of ≥0.05 μg/L had higher sensitivity (80 %) but lower specificity (89 %), compared with a secondary increase of ≥0.5 μg/L (16 % sensitivity, 98 % specificity), to detect secondary radiological findings.

CONCLUSIONS

Secondary increases in serum levels of S100B, even as low as ≥0.05 μg/L, beyond 48 h after TBI are strongly correlated to the development of clinically significant secondary radiological findings.

Association of ICP, CPP, CT findings and S-100B and NSE in severe traumatic head injury. Prognostic value of the biomarkers

OBJECTIVE

The association was studied of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) on S-100B and neuron-specific enolase (NSE) in severe traumatic brain injury (sTBI). The relationship was explored between biomarkers, ICP, CPP, CT-scan classifications and the clinical outcome.

MATERIALS AND METHODS

Data were collected prospectively and consecutively in 48 patients with Glasgow Coma Scale score ≤ 8, age 15-70 years. NSE and S-100B were analysed during 5 consecutive days. The initial and follow-up CT-scans were classified according to the Marshall, Rotterdam and Morris-Marshall classifications. Outcome was evaluated with extended Glasgow outcome scale at 3 months.

RESULTS

Maximal ICP and minimal CPP correlated with S-100B and NSE levels. Complex relations between biomarkers and CT classifications were observed. S-100B bulk release (AUC = 0.8333, p = 0.0009), and NSE at 72 hours (AUC = 0.8476, p = 0.0045) had the highest prediction power of mortality. Combining Morris-Marshall score and S-100B bulk release improved the prediction of clinical outcome (AUC = 0.8929, p = 0.0008).

CONCLUSION

Biomarker levels are associated with ICP and CPP and reflect different aspects of brain injury as evaluated by CT-scan. The biomarkers might predict mortality. There are several pitfalls influencing the interpretation of biomarker data in respect to ICP, CPP, CT-findings and clinical outcome.

Serum biomarkers of brain injury to classify outcome after pediatric cardiac arrest*

OBJECTIVES

Morbidity and mortality in children with cardiac arrest largely result from neurologic injury. Serum biomarkers of brain injury can potentially measure injury to neurons (neuron-specific enolase), astrocytes (S100b), and axons (myelin basic protein). We hypothesized that serum biomarkers can be used to classify outcome from pediatric cardiac arrest.

DESIGN

Prospective observational study.

SETTING

Single tertiary pediatric hospital.

PATIENTS

Forty-three children with cardiac arrest.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured serum neuron-specific enolase, S100b, and myelin basic protein on days 1-4 and 7 after cardiac arrest. We recorded demographics, details of the cardiac arrest and resuscitation, and Pediatric Cerebral Performance Category at hospital discharge and 6 months. We analyzed the association of biomarker levels at 24, 48, and 72 hours with favorable (Pediatric Cerebral Performance Category 1-3) or unfavorable (Pediatric Cerebral Performance Category 4-6) outcome and mortality. Forty-three children (49% female; mean age of 5.9 ± 6.3) were enrolled and 17 (40%) died. Serum S100b concentrations peaked earliest, followed by neuron-specific enolase and finally myelin basic protein. Serum neuron-specific enolase and S100b concentrations were increased in the unfavorable versus favorable outcome group and in subjects who died at all time points (all p < 0.05). Serum myelin basic protein at 24 and 72 hours correctly classified survival but not good versus poor outcome. Using best specificity, serum S100b and neuron-specific enolase had optimal positive and negative predictive values at 24 hours to classify both favorable versus unfavorable outcome and survival, whereas serum myelin basic protein's best accuracy occurred at 48 hours. Receiver operator curves for serum S100b and neuron-specific enolase to classify favorable versus unfavorable outcome at 6 months were superior to clinical variables.

CONCLUSIONS

Preliminary data show that serum S100b, neuron-specific enolase, and myelin basic protein may aid in outcome classification of children surviving cardiac arrest.

S100B Protein as a Post-traumatic Biomarker for Prediction of Brain Death in Association With Patient Outcomes

BACKGROUND

S100B is a calcium-binding protein, belonging to the S100 family proteins which are characterized by their high solubility and, currently, comprises 21 members which are expressed in a cell-specific manner. If we can predict the possibility of definite brain death after brain injury, we will rescue some organs of body to transplant proposes.

OBJECTIVES

In this regard our study focused on the S100B protein value in predicting brain death after head trauma. In this study, the use of serum level of protein S100, 24 hours after trauma has been considered as a reliable index for predicting brain death.

PATIENTS AND METHODS

72 patients (50 male and 22 female) aged 5 - 80 years old (median 40 ± 17.72 years) with severe head traumas (GCS≤8) were recruited in this cross-sectional study. Glasgow Coma Scale (GCS) and computed tomography (CT) scan findings were recorded for all patients, and then a single 5mL blood sample was obtained from each patient on admission, after 48 hours and a week later or after brain death to determine the level of S100B protein.

RESULTS

Primary and the last GCS of patients had a predictive value in determining brain death (P < 0.0005), also there was a significant correlation between GCS and level of S100B protein. There was a significant correlation between CT scan findings and S100B protein only after 48 hours of trauma.

CONCLUSIONS

Changes in S100B protein, especially the levels of this dimer 48 hours after trauma can be used as marker to predict brain death. Alongside other known prognostic factors such as age, GCS and diameters of the pupils, however, this factor individually can not conclusive predict the patient's clinical course and incidence of brain death. However, it is suitable to use GCS, CT scan, clinical symptoms and biomarkers together for a perfect prediction of brain death.

Clinical use of the calcium-binding S100B protein

S100B is a calcium-binding protein most abundant in neuronal tissue. It is expressed in glia cells and Schwann cells and exerts both intra- and extracellular effects. Depending on the concentration, secreted S100B exerts either trophic or toxic effects. Its functions have been extensively studied but are still not fully understood. It can be measured in cerebrospinal fluid and blood, and increased S100B level in blood can be seen after, e.g., traumatic brain injury, certain neurodegenerative disorders and malignant melanoma. This chapter provides a short background of protein S100B, commercially available methods of analysis, and its clinical use.

Protein S100B in Traumatic Brain Injury

Protein S100B is a small calcium-binding protein expressed in astroglial cells in the central nervous system. Its concentration increases in cerebrospinal fluid and blood after traumatic brain injury. There are several commercially available methods for analyzing serum S100B. The clinical use of serum S100B is mainly in minor head injury, as a complement to existing guidelines in order to help clinicians to determine who could safely be discharged without a previous CT scan. S100B in severe TBI is still being studied as a marker for secondary neurological complications, but has not yet had an impact in this specific area. Recent research on the clinical use of S100B in pediatric TBI has shown promising results, and the introduction of S100B in minor head injuries could have even greater impact than for adults. However, more research needs to be done before a biomarker can be clinically used in pediatric TBI.

Role of the S100B serum biomarker in the treatment of children suffering from mild traumatic brain injury

OBJECT

The aim of this study was to provide a systematic update of the current literature regarding the clinical role of the S100B serum biomarker in the initial evaluation of children who have sustained a mild traumatic brain injury (TBI).

METHODS

Searches in MEDLINE were defined with the keywords "mild TBI children S100," "mild TBI pediatric S100," and "children S100 brain injury." From the pool of obtained studies, those that had the inclusion criteria of mild TBI only or mixed types of TBI but including detailed information about groups of children with mild TBI were used.

RESULTS

Few studies were identified and fewer included more than 100 cases. The prospective studies showed that the S100B biomarker levels could be influenced by patient age and the time frame between head injury and blood sampling. Moreover, extracranial sources of S100B or additional injuries could influence the measured levels of this biomarker. A normal value of S100B in children with mild TBI could rule out injury-associated abnormalities on CT scans in the majority of reported cases.

CONCLUSIONS

The vulnerability of S100B serum levels to the influences of patient age, blood sampling time, and extracranial S100B release limits the biomarker's role in the initial evaluation of children with mild TBI. The application of S100B in pediatric mild TBI cases has an elusive role, although it could help in selected cases to avoid unnecessary head CT scans.

Biomarkers for the diagnosis, prognosis, and evaluation of treatment efficacy for traumatic brain injury

Traumatic brain injury (TBI) remains a serious health concern, and TBI is one of the leading causes of death and disability, especially among young adults. Although preventive education, increased usage of safety devices, and TBI management have dramatically increased the potential for surviving a brain injury, there is still a need to develop reliable methods to diagnose TBI, the secondary pathologies associated with TBI, and predicting the outcomes of TBI. Biomarkers (changes of amount or activity in a biomolecule that reflect injury or disease) have shown promise in the diagnosis of several conditions, including cancer, heart failure, infection, and genetic disorders. A variety of proteins, small molecules, and lipid products have been proposed as potential biomarkers of brain damage from TBI. Although some of these changes have been reported to correlate with mortality and outcome, further research is required to identify prognostic biomarkers. This need is punctuated in mild injuries that cannot be readily detected using current techniques, as well as in defining patient risk for developing TBI-associated secondary injuries.

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.

Alpha II-spectrin breakdown products serve as novel markers of brain injury severity in a canine model of hypothermic circulatory arrest

BACKGROUND

The development of specific biomarkers to aid in the diagnosis and prognosis of neuronal injury is of paramount importance in cardiac surgery. Alpha II-spectrin is a structural protein abundant in neurons of the central nervous system and cleaved into signature fragments by proteases involved in necrotic and apoptotic cell death. We measured cerebrospinal fluid alpha II-spectrin breakdown products (alphaII-SBDPs) in a canine model of hypothermic circulatory arrest (HCA) and cardiopulmonary bypass.

METHODS

Canine subjects were exposed to either 1 hour of HCA (n = 8; mean lowest tympanic temperature 18.0 +/- 1.2 degrees C) or standard cardiopulmonary bypass (n = 7). Cerebrospinal fluid samples were collected before treatment and 8 and 24 hours after treatment. Using polyacrylamide gel electrophoresis and immunoblotting, SBDPs were isolated and compared between groups using computer-assisted densitometric scanning. Necrotic versus apoptotic cell death was indexed by measuring calpain and caspase-3 cleaved alphaII-SBDPs (SBDP 145+150 and SBDP 120, respectively).

RESULTS

Animals undergoing HCA demonstrated mild patterns of histologic cellular injury and clinically detectable neurologic dysfunction. Calpain-produced alphaII-SBDPs (150 kDa+145 kDa bands-necrosis) 8 hours after HCA were significantly increased (p = 0.02) as compared with levels before HCA, and remained elevated at 24 hours after HCA. In contrast, caspase-3 alphaII-SBDP (120 kDa band-apoptosis) was not significantly increased. Animals receiving cardiopulmonary bypass did not demonstrate clinical or histologic evidence of injury, with no increases in necrotic or apoptotic cellular markers.

CONCLUSIONS

We report the use of alphaII-SBDPs as markers of neurologic injury after cardiac surgery. Our analysis demonstrates that calpain- and caspase-produced alphaII-SBDPs may be an important and novel marker of neurologic injury after HCA.

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.

A survey of static and dynamic work postures of operating room staff

Purpose

To determine reciprocal and synergistic effects of acute intracranial hypertension and ARDS on neuronal and pulmonary damage and to define possible mechanisms.

Methods

Twenty-eight mechanically ventilated pigs were randomized to four groups of seven each: control; acute intracranial hypertension (AICH); acute respiratory distress syndrome (ARDS); acute respiratory distress syndrome in combination with acute intracranial hypertension (ARDS + AICH). AICH was induced with an intracranial balloon catheter and the inflation volume was adjusted to keep intracranial pressure (ICP) at 30–40 cmH₂O. ARDS was induced by oleic acid infusion. Respiratory function, hemodynamics, extravascular lung water index (ELWI), lung and brain computed tomography (CT) scans, as well as inflammatory mediators, S100B, and neuronal serum enolase (NSE) were measured over a 4-h period. Lung and brain tissue were collected and examined at the end of the experiment.

Results

In both healthy and injured lungs, AICH caused increases in NSE and TNF-alpha plasma concentrations, extravascular lung water, and lung density in CT, the extent of poorly aerated (dystelectatic) and atelectatic lung regions, and an increase in the brain tissue water content. ARDS and AICH in combination induced damage in the hippocampus and decreased density in brain CT.

Conclusions

AICH induces lung injury and also exacerbates pre-existing damage. Increased extravascular lung water is an early marker. ARDS has a detrimental effect on the brain and acts synergistically with intracranial hypertension to cause histological hippocampal damage.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-011-2232-2) contains supplementary material, which is available to authorized users.