Serum glial fibrillary acidic protein as a biomarker for intracerebral haemorrhage in patients with acute stroke

Translating basic science research to clinical application: models and strategies for intracerebral hemorrhage

Preclinical stroke models provide insights into mechanisms of cellular injury and potential therapeutic targets. Renewed efforts to standardize preclinical practices and adopt more rigorous approaches reflect the assumption that a better class of compounds will translate into clinical efficacy. While the need for novel therapeutics is clear, it is also critical that diagnostics be improved to allow for more rapid treatment upon hospital admission. Advances in imaging techniques have aided in the diagnosis of stroke, yet current limitations and expenses demonstrate the need for new and complementary approaches. Intracerebral hemorrhage (ICH) exhibits the highest mortality rate, displays unique pathology and requires specialized treatment strategies relative to other forms of stroke. The aggressive nature and severe consequences of ICH underscore the need for novel therapeutic approaches as well as accurate and expeditious diagnostic tools. The use of experimental models will continue to aid in addressing these important issues as the field attempts to translate basic science findings into the clinical setting. Several preclinical models of ICH have been developed and are widely used to recapitulate human pathology. Because each model has limitations, the burden lies with the investigator to clearly define the question being asked and select the model system that is most relevant to that question. It may also be necessary to optimize and refine pre-existing paradigms, or generate new paradigms, as the future success of translational research is dependent upon the ability to mimic human sequelae and assess clinically relevant outcome measures as means to evaluate therapeutic efficacy.

Evolving role of biomarkers in acute cerebrovascular disease

The development of a clinically validated biomarker of acute cerebral ischemia would have the potential to facilitate the use of time-sensitive reperfusion strategies, allow for individualization of patient care by predicting relative risk of hemorrhage and volume of penumbral tissue, and add valuable prognostic information for patients presenting with acute stroke. Additionally, a stroke biomarker might benefit early stage clinical research by serving as a surrogate measure of ischemic injury. Although at present there are no clinically validated biomarkers of acute stroke, previous studies have focused on markers associated with different components of the ischemic cascade, including microglial activation, inflammation, oxidative stress, neuronal injury, hemostasis, and endothelial dysfunction. Evolving technologies have provided high throughput approaches to investigate potential gene and protein signatures, and methods to measure newly discovered markers of cell death and immune responses. Prior to defining the clinical utility of stroke biomarkers, it is critical to understand the inherent limitations of a biomarker-based approach and define its potential value for providing adjunctive diagnostic and prognostic information. The identification and validation of a clinically relevant biomarker, or panel of markers, of stroke will ultimately require incorporation of both stringent research design and assessment in the clinical context in which the marker will be used.

Future Trends in Biomarker Immunoassay Development

The evaluation of specific biomarkers for assessment of TBI and other neurological conditions, development of an immunoassay, and its translation to clinical laboratories are discussed. This chapter provides brief information concerning interrelations between assay development, clinical indications, regulatory restrictions, and future trends in drug/test co-development for TBI biomarkers. The strategy of biomarker assay adaptation to personalized medicine is outlined.

Astrogliosis: a target for intervention in intracerebral hemorrhage?

Intracerebral hemorrhage (ICH) is a debilitating neurological injury, accounting for 10-15 % of all strokes. Despite neurosurgical intervention and supportive care, the 30-day mortality rate remains ~50 %, with ICH survivors frequently displaying neurological impairments and requiring long-term assisted care. Unfortunately, the lack of medical interventions to improve clinical outcomes has led to the notion that ICH is the least treatable form of stroke. Hence, additional studies are warranted to better understand the pathophysiology of ICH. Astrogliosis is an underlying astrocytic response to a wide range of brain injuries and postulated to have both beneficial and detrimental effects. However, the molecular mechanisms and functional roles of astrogliosis remain least characterized following ICH. Herein, we review the functional roles of astrogliosis in brain injuries and raise the prospects of therapeutically targeting astrogliosis after ICH.

Differentiating ischemic from hemorrhagic stroke using plasma biomarkers: the S100B/RAGE pathway

Although neuroimaging is useful in differentiating ischemic (IS) from hemorrhagic (ICH) stroke in the Emergency Department, a wide-available rapid biochemical test would add advantages in the pre-hospital triage and management of stroke patients. Our aim was to examine the predictive value of a panel of blood-borne biomarkers to differentiate IS from ICH. Admission blood samples obtained within 24h from stroke symptoms onset were tested by ELISA for CRP, D-dimer, sRAGE, MMP9, S100B, BNP, NT-3, caspase-3, chimerin-II, secretagogin, cerebellin and NPY. The complete protocol was achieved in 915 patients (776 IS, 139 ICH). Among blood samples obtained <6 h from symptoms onset (n=337), S100B levels were increased in ICH (107.58 vs 58.70 pg/mL; p<0.001) whereas sRAGE levels were decreased (0.77 vs 1.02 ng/mL; p=0.009) as compared to IS. In this subset of patients S100B (OR 3.97 95% CI 1.82-8.68; p=0.001) and sRAGE (OR 0.22 95% CI 0.10-0.52; p<0.001) were independently associated with ICH. A regression tree was created by CART method showing good classification ability (AUC=0.762). Similar results were found for samples obtained within 3 h. In conclusion, a combination of biomarkers including those of the S100B/RAGE pathway seems promising to achieve a rapid biochemical diagnosis of IS versus ICH in the first hours from symptoms onset. This article is part of a Special Issue entitled: Translational Proteomics.

Correlational study of the serum levels of the glial fibrillary acidic protein and neurofilament proteins in Parkinson's disease patients

OBJECTIVE

To investigate changes in the serum levels of the glial fibrillary acidic protein (GFAP) and neurofilament proteins (NFs) in patients with Parkinson's disease (PD) and to determine their clinical significance.

METHODS

In this study, 82 subjects were divided into 3 groups: the PD group, the acute cerebral infarction (ACI) group, and a normal control group. The serum levels of GFAP and NFs were measured using a sandwich ELISA assay.

RESULTS

The serum levels of GFAP and NFs were significantly higher in the PD and the ACI groups than in the normal control group (P<0.05). There was no significant difference between the PD group and the ACI group (P>0.05). The serum level of GFAP in the PD group had no significant correlation with duration of the disease or age (P>0.05). The serum level of NFs in the PD group was significantly correlated with duration of the disease and age (P<0.05).

CONCLUSIONS

The serum levels of GFAP and NFs were significantly higher in the PD group than in the normal group, indicating that astrocytic activity may remain elevated during the axonal degeneration that occurs over duration of the disease, although this activity is not specific to the disease.

Diagnostic accuracy of plasma glial fibrillary acidic protein for differentiating intracerebral hemorrhage and cerebral ischemia in patients with symptoms of acute stroke

BACKGROUND

Glial fibrillary acidic protein (GFAP) is a biomarker candidate indicative of intracerebral hemorrhage (ICH) in patients with symptoms of acute stroke. GFAP is released rapidly in the presence of expanding intracerebral bleeding, whereas a more gradual release occurs in ischemic stroke. In this study the diagnostic accuracy of plasma GFAP was determined in a prospective multicenter approach.

METHODS

Within a 1-year recruitment period, patients suspected of having acute (symptom onset<4.5 h before admission) hemispheric stroke were prospectively included into the study in 14 stroke centers in Germany and Switzerland. A blood sample was collected at admission, and plasma GFAP was measured by use of an electrochemiluminometric immunoassay. The final diagnosis, established at hospital discharge, was classified as ICH, ischemic stroke, or stroke mimic.

RESULTS

The study included 205 patients (39 ICH, 163 ischemic stroke, 3 stroke mimic). GFAP concentrations were increased in patients with ICH compared with patients with ischemic stroke [median (interquartile range) 1.91 μg/L (0.41-17.66) vs 0.08 μg/L (0.02-0.14), P<0.001]. Diagnostic accuracy of GFAP for differentiating ICH from ischemic stroke and stroke mimic was high [area under the curve 0.915 (95% CI 0.847-0.982), P<0.001]. A GFAP cutoff of 0.29 μg/L provided diagnostic sensitivity of 84.2% and diagnostic specificity of 96.3% for differentiating ICH from ischemic stroke and stroke mimic.

CONCLUSIONS

Plasma GFAP analysis performed within 4.5 h of symptom onset can differentiate ICH and ischemic stroke. Studies are needed to evaluate a GFAP point-of-care system that may help optimize the prehospital triage and management of patients with symptoms of acute stroke.

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.

Glial fibrillary acidic protein as a brain injury biomarker in children undergoing extracorporeal membrane oxygenation

OBJECTIVE

To determine whether, in children, plasma glial fibrillary acidic protein is associated with brain injury during extracorporeal membrane oxygenation and with mortality.

DESIGN

Prospective, observational study.

SETTING

Pediatric intensive care unit in an urban tertiary care academic center.

PATIENTS

Neonatal and pediatric patients on extracorporeal membrane oxygenation (n = 22).

INTERVENTIONS

Serial blood sampling for glial fibrillary acidic protein measurements.

MEASUREMENTS AND MAIN RESULTS

Prospective patients age 1 day to 18 yrs who required extracorporeal membrane oxygenation from April 2008 to August 2009 were studied. Glial fibrillary acidic protein was measured using an electrochemiluminescent immunoassay developed at Johns Hopkins. Control samples were collected from 99 healthy children (0.5-16 yrs) and 59 neonatal intensive care unit infants without neurologic injury. In controls, the median glial fibrillary acidic protein concentration was 0.055 ng/mL (interquartile range, 0-0.092 ng/mL) and the 95th percentile of glial fibrillary acidic protein was 0.436 ng/mL. In patients on extracorporeal membrane oxygenation, plasma glial fibrillary acidic protein was measured at 6, 12, and every 24 hrs after cannulation. We enrolled 22 children who underwent extracorporeal membrane oxygenation. Median age was 7 days (interquartile range, 2 days to 9 yrs), and primary extracorporeal membrane oxygenation indication was: cardiac failure, six of 22 (27.3%); respiratory failure, 12 of 22 (54.5%); extracorporeal cardiopulmonary resuscitation, three of 22 (13.6%); and sepsis, one of 22 (4.6%). Seven of 22 (32%) patients developed acute neurologic injury (intracranial hemorrhage, brain death, or cerebral edema diagnosed by imaging). Fifteen of 22 (68%) survived to hospital discharge. In the extracorporeal membrane oxygenation group, peak glial fibrillary acidic protein levels were higher in children with brain injury than those without (median, 5.9 vs. 0.09 ng/mL, p = .04) and in nonsurvivors compared with survivors to discharge (median, 5.9 vs. 0.09 ng/mL, p = .04). The odds ratio for brain injury for glial fibrillary acidic protein >0.436 ng/mL vs. normal was 11.5 (95% confidence interval, 1.3-98.3) and the odds ratio for mortality was 13.6 (95% confidence interval, 1.7-108.5).

CONCLUSIONS

High glial fibrillary acidic protein during extracorporeal membrane oxygenation is significantly associated with acute brain injury and death. Brain injury biomarkers may aid in outcome prediction and neurologic monitoring of patients on extracorporeal membrane oxygenation to improve outcomes and benchmark new therapies.

Blood biomarkers of ischemic stroke

This review provides a summary of the protein and RNA biomarkers that have been studied for the diagnosis and assessment of ischemic stroke. Many of the biomarkers identified relate to the pathophysiology of ischemic stroke, including ischemia of CNS tissue, acute thrombosis and inflammatory response. These biomarkers are summarized by their intended clinical application in ischemic stroke including diagnosis, prediction of stroke severity and outcome, and stratification of patients for stroke therapy. Among the biomarkers discussed are recent whole genome studies using RNA expression profiles to diagnose ischemic stroke and stroke etiology. Though many candidate blood based biomarkers for ischemic stroke have been identified, none are currently used in clinical practice. With further well designed study and careful validation, the development of blood biomarkers to improve the care of patients with ischemic stroke may be achieved.

A specific miRNA signature in the peripheral blood of glioblastoma patients

The prognosis of patients afflicted by glioblastoma remains poor. Biomarkers for the disease would be desirable in order to allow for an early detection of tumor progression or to indicate rapidly growing tumor subtypes requiring more intensive therapy. In this study, we investigated whether a blood-derived specific miRNA fingerprint can be defined in patients with glioblastoma. To this end, miRNA profiles from the blood of 20 patients with glioblastoma and 20 age- and sex-matched healthy controls were compared. Of 1158 tested miRNAs, 52 were significantly deregulated, as assessed by unadjusted Student's t-test at an alpha level of 0.05. Of these, two candidates, miR-128 (up-regulated) and miR-342-3p (down-regulated), remained significant after correcting for multiple testing by Benjamini-Hochberg adjustment with a p-value of 0.025. The altered expression of these two biomarkers was confirmed in a second cohort of glioblastoma patients and healthy controls by real-time PCR and validated for patients who had received neither radio- nor chemotherapy and for patients who had their glioblastomas resected more than 6 months ago. Moreover, using machine learning, a comprehensive miRNA signature was obtained that allowed for the discrimination between blood samples of glioblastoma patients and healthy controls with an accuracy of 81% [95% confidence interval (CI) 78-84%], specificity of 79% (95% CI 75-83%) and sensitivity of 83% (95% CI 71-85%). In summary, our proof-of-concept study demonstrates that blood-derived glioblastoma-associated characteristic miRNA fingerprints may be suitable biomarkers and warrant further exploration.

Perihematomal pathological changes in neurons and astrocytes following acute cerebral hemorrhage

We aim to investigate the pathological temporospatial characteristics of brain cell injury in the perihematomal areas. Brain autopsy samples from 44 consecutive cases of intracerebral hemorrhage were processed and analyzed following immunohistochemical staining for neurofilament (NF) and glial fibrillary acidic protein (GFAP). NF and GFAP positive cells were scored and graded according to the distance from the hematoma and the time from the onset of hematoma formation. The tissues from the same region on the contralateral side of the brain were used as controls. Neurons in the perihematomal areas exhibited pyknosis or swollen necrosis, while astrocytes were swollen. Morphological abnormalities pertaining to NF appearance were attenuated with increasing distance from the hematoma wall, but were exacerbated with prolonged bleeding time. The level of NF staining abnormality was positively correlated with time from the onset of hematoma within 7 days of intracerebral hemorrhage. In contrast, the intensity of GFAP staining was negatively correlated with time from the onset of hematoma formation. This immunoreactivity was significantly higher closer to hematoma. Taken together, these data indicate that pathological alterations in neurons and astrocytes in the perihematomal area change with time from the onset of hematoma formation.

Plasmatic markers in hemorrhagic stroke

Stroke is the third most common cause of death in the United States and it is the leading cause of disability. Early diagnosis and immediate therapeutic interventions are important factors to reduce the extent of brain tissue damage and the risk of stroke-related death. A rapid blood test that can confirm the clinical or imaging diagnosis or that can add to the stratification of the risk would be very useful. Such a test has to be validated in large studies and has to be based on a simple and low-cost technology. Many biological markers were tested for their ability to serve as 'would-be' stroke biological markers; some of them appear to have a place in the diagnostic work-up of stroke patients. These molecules include Glial Fibrillary Acidic Protein (GFAP), the N-methyl-D-aspartate receptor (NMDA), APO C-III, APO C-I, PARK7, nucleoside diphosphate kinase A (NDKA), S100B, B-type neurotrophic growth factor, von Willebrand factor, matrix metalloproteinase-9, and monocyte chemotactic protein-1. There are obvious limitations to this study, among them the fact that disability does not necessarily correlate with the amount of cerebral tissue lost (the site of stroke may be more important) and the role of the blood-brain barrier in delaying the release of the neuronal proteins in the blood stream. Further studies are awaited to confirm the role of these molecules in the management of acute stroke patients.

Levels of phosphorylated axonal neurofilament subunit H (pNfH) are increased in acute ischemic stroke

For the study of stroke outcomes, there is the need for measurements of severity of stroke damage. Phosphorylated neurofilament heavy protein (pNfH) levels are elevated in axonal injury. We have measured levels of pNfH in stroke and correlated these levels with measures of stroke severity. Blood samples were collected from 54 ischaemic stroke patients at day 1, week 1 (days 7-10) and weeks 3-6, and an ELISA was used to measure pNfH levels in each patient at each time-point. Serum pNfH levels were significantly elevated in stroke patients compared to healthy controls. The levels were low at day 1, higher at day 7 and reached a peak at week 3, the latest day that we assessed. Significant associations were found between the pNfH levels at week 3 and early and stroke severity, size and outcome. Blood pNfH levels that reflect the severity of ischaemic stroke, are correlated with outcome and rise during the weeks after stroke. This may be a useful measure of tissue damage in stroke.

Astroglial proteins as diagnostic markers of acute intracerebral hemorrhage-pathophysiological background and clinical findings

The time span from symptom onset to treatment initiation remains a critical variable determining the efficacy of thrombolysis in acute ischemic stroke. To date, performing a brain scan is indispensable prior to therapy in order to differentiate between patients with ischemic stroke and those with intracerebral hemorrhage (ICH). This causes substantial treatment delay, as thrombolysis cannot be applied prior to hospital admission at much earlier time points. Recently, brain-specific astroglial proteins (i.e., glial fibrillary acidic protein (GFAP), S100B) were identified to be released rapidly from the cytoplasm of destroyed cells in case of acute ICH. Elevated serum concentrations were found within the first 6 h after ICH onset. In contrast, in ischemic stroke, these proteins are released with delay, mirroring the more gradual occurrence of necrotic cell death and blood brain barrier disruption. S100B and GFAP may qualify as candidate serum biomarkers which are able to differentiate between ischemic stroke and ICH in the emergency phase of stroke. This minireview enlightens the pathophysiological background of this finding and provides an overview on currently available clinical data.

Clinical application of blood biomarkers in cerebrovascular disease

Identifying a biomarker or panel of biomarkers of cerebral ischemia would have a major impact on the care of stroke patients by facilitating early management decisions and individualization of care. Biochemical surrogates of cerebral ischemia might also play an important role by identifying relevant pathways for novel therapeutic strategies and by facilitating early clinical trials in cerebrovascular disease. Serum biomarkers related to pathways of hemostasis, oxidation and inflammation, or alterations in glial and neuronal proteins, have been identified but none have been recommended for routine clinical use. This review describes the most promising biomarkers of cerebrovascular disease and the context and limitations in which they have been studied.

S100B and brain natriuretic peptide predict functional neurological outcome after intracerebral haemorrhage

OBJECTIVE

To determine the predictive value of S100b and brain natriuretic peptide (BNP) in order to determine accurately and quickly a discharge prognosis after primary supratentorial intracerebral haemorrhage (ICH).

METHODS

After IRB approval and informed consent, blood samples were obtained and analysed from 28 adult patients consecutively admitted to the neuroscience intensive care unit with computed tomography-proven supratentorial ICH from June 2003 and December 2004 within the first 24 h after symptom onset for S100b and BNP. Functional outcomes on discharge were dichotomized to favourable (mRS < 3) or unfavourable.

RESULTS

BNP (a neurohormone) and S100b (a marker of glial activation) were found to be independently highly predictive of functional neurological outcome at the time of discharge as measured by the modified Rankin Score (BNP: p < 0.01, r = 0.46; S100b: p < 0.01, r = 0.42) and the Barthel Index (BNP: p < 0.01, r = 0.54; s100b: p < 0.01, r = 0.50). Although inclusion of either biomarker produced additive value when included with traditional clinical prognostic variables, such as the ICH score (Barthel index: p < 0.01, r = 0.66; mRS: p < 0.01, r = 0.96), little predictive power is added with inclusion of both biomarkers in a regression model for neurological outcome.

CONCLUSIONS

Serum S100b and BNP levels in the first 24 h after injury accurately predict neurological function at discharge after supratentorial ICH.

Stroke biomarkers: progress and challenges for diagnosis, prognosis, differentiation, and treatment

BACKGROUND

Stroke is a devastating condition encompassing a wide range of pathophysiological entities that include thrombosis, hemorrhage, and embolism. Current diagnosis of stroke relies on physician clinical examination and is further supplemented with various neuroimaging techniques. A single set or multiple sets of blood biomarkers that could be used in an acute setting to diagnosis stroke, differentiate between stroke types, or even predict an initial/reoccurring stroke would be extremely valuable.

CONTENT

We discuss the current classification, diagnosis, and treatment of stroke, focusing on use of novel biomarkers (either solitary markers or multiple markers within a panel) that have been studied in a variety of clinical settings.

SUMMARY

The current diagnosis of stroke remains hampered and delayed due to lack of a suitable mechanism for rapid (ideally point-of-care), accurate, and analytically sensitive biomarker-based testing. There is a clear need for further development and translational research in this area. Potential biomarkers identified need to be transitioned quickly into clinical validation testing for further evaluation in an acute stroke setting; to do so would impact and improve patient outcomes and quality of life.

Invited article: searching for oracles? Blood biomarkers in acute stroke

Emerging data suggest that a wide array of measurable biomarkers in blood may provide a novel window into the pathophysiology of stroke. In this review, we survey the state of progress in the field. Three specific questions are assessed. Can biomarkers augment the clinical examination and powerful brain imaging tools to enhance the accuracy of the diagnostic process? Can biomarkers be used to help triage patients for thrombolytic therapy? Can biomarkers help predict patients who are most susceptible to malignant infarction? Many encouraging molecular candidates have been found that appear to match the known cascades of neurovascular injury after stroke. However, whether these putative biomarkers may indeed have direct clinical utility remains to be quantitatively validated. Larger clinical trials are warranted to establish the sensitivity and specificity of biomarkers for routine use in clinical stroke.

Molecular biomarkers in stroke diagnosis and prognosis

Serum biomarkers related to the cascade of inflammatory, hemostatic, glial and neuronal perturbations have been identifed to diagnose and characterize intracerebral hemorrhage and cerebral ischemia. Interpretation of most markers is confounded by their latent rise, blood-brain barrier effects, the heterogeneity of etiologies and the wide range of normal values, limiting their application for early diagnosis, lesion size estimation and long-term outcome prediction. Certain hemostatic and inflammatory constituents have been found to predict response to thrombolysis and worsening due to infarct progression and secondary hemorrhage, offering a potential role for improved treatment selection and individualization of therapy. Biomarkers will become increasingly relevant for developing targets for neuroprotective therapies, monitoring response to treatment and as surrogate end points for treatment trials.

Dysfunctions of neuronal and glial intermediate filaments in disease

Intermediate filaments (IFs) are abundant structures found in most eukaryotic cells, including those in the nervous system. In the CNS, the primary components of neuronal IFs are alpha-internexin and the neurofilament triplet proteins. In the peripheral nervous system, a fifth neuronal IF protein known as peripherin is also present. IFs in astrocytes are primarily composed of glial fibrillary acidic protein (GFAP), although vimentin is also expressed in immature astrocytes and some mature astrocytes. In this Review, we focus on the IFs of glial cells (primarily GFAP) and neurons as well as their relationship to different neurodegenerative diseases.

Mechanisms and markers for hemorrhagic transformation after stroke

Intracerebral hemorrhagic transformation is a multifactorial phenomenon in which ischemic brain tissue converts into a hemorrhagic lesion with blood vessel leakage. Hemorrhagic transformation can significantly contribute to additional brain injury after stroke. Especially threatening are the thrombolytic-induced hemorrhages after reperfusion therapy with tissue plasminogen activator (tPA), the only treatment available for ischemic stroke. In this context, it is important to understand its underlying mechanisms and identify early markers of hemorrhagic transformation, so that we can both search for new treatments as well as predict clinical outcomes in patients. In this review, we discuss the emerging mechanisms for hemorrhagic transformation after stroke, and briefly survey potential molecular, genetic, and neuroimaging markers that might be used for early detection of this challenging clinical problem.

Blood biomarkers in the diagnosis of ischemic stroke: a systematic review

BACKGROUND AND PURPOSE

The diagnosis of ischemic stroke can be difficult. CT may be normal in the early stages of ischemic stroke or in patients with minor symptoms and MR is not always possible. Many blood markers have been proposed for the diagnosis of stroke in the acute setting.

METHODS

We have systematically reviewed the diagnostic literature and found 21 studies testing 58 single biomarkers and 7 panels of several biomarkers. Although all show either a high sensitivity or specificity, there are limitations in the design and reporting of all the studies that mean no biomarker can be recommended for use in clinical practice.

CONCLUSIONS

We make recommendations for the design and reporting of studies of diagnostic blood biomarkers in stroke.

Serum levels of glial fibrillary acidic protein correlate to tumour volume of high-grade gliomas

OBJECTIVES

To investigate serum levels of glial fibrillary acidic protein (GFAP) and S-100B in patients with newly diagnosed high-grade gliomas.

MATERIALS AND METHODS

GFAP and S-100B were measured by enzyme-linked immunosorbent assay techniques in preoperative serum from 31 patients with high-grade gliomas. A database with clinical, radiological and histological variables was created for statistical analyses.

RESULTS

Mean serum levels of 239 ng/l (range 30-1210 ng/l) for GFAP and 58.3 ng/l (range 22-128 ng/l) for S-100B were found. Of the 31 patients, 16 had elevated levels of GFAP while only two showed increased S-100B concentrations. Tumour size was the only variable significantly associated with serum levels of GFAP (P < 0.0001) with a linear correlation coefficient of 0.67.

CONCLUSIONS

Serum levels of GFAP demonstrated a linear correlation to tumour volume in patients with high-grade gliomas. GFAP seems to be a more reliable biomarker in patients with high-grade gliomas than the commercially available S-100B.

Protection against human immunodeficiency virus type 1 Tat neurotoxicity by Ginkgo biloba extract EGb 761 involving glial fibrillary acidic protein

Human immunodeficiency virus (HIV)-1 Tat protein is an important pathogenic factor in HIV-associated neuropathogenesis. Despite recent progress, the molecular mechanisms underlying Tat neurotoxicity are still not completely understood. However, few therapeutics have been developed to specifically target HIV infection in the brain. Recent development of an inducible brain-specific Tat transgenic mouse model has made it possible to define the mechanisms of Tat neurotoxicity and evaluate anti-neuroAIDS therapeutic candidates in the context of a whole organism. Herein, we demonstrate that administration of EGb 761, a standardized formulation of Ginkgo biloba extract, markedly protected Tat transgenic mice from Tat-induced developmental retardation, inflammation, death, astrocytosis, and neuron loss. EGb 761 directly down-regulated glial fibrillary acidic protein (GFAP) expression at both protein and mRNA levels. This down-regulation was, at least in part, attributable to direct effects of EGb 761 on the interactions of the AP1 and NF-kappaB transcription factors with the GFAP promoter. Most strikingly, Tat-induced neuropathological phenotypes including macrophage/microglia activation, central nervous system infiltration of T lymphocytes, and oxidative stress were significantly alleviated in GFAP-null/Tat transgenic mice. Taken together, these results provide the first evidence to support the potential for clinical use of EGb 761 to treat HIV-associated neurological diseases. Moreover, these findings suggest for the first time that GFAP activation is directly involved in Tat neurotoxicity, supporting the notion that astrocyte activation or astrocytosis may directly contribute to HIV-associated neurological disorders.

Serum Glial Fibrillary Acidic Protein Is Related to Focal Brain Injury and Outcome After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Aneurysmal subarachnoid hemorrhage (aSAH) stands out from other subtypes of stroke because of the high early mortality and the risk of complications. Serum glial fibrillary acidic protein (s-GFAP) concentrations are increased after stroke. The aim of this study was to investigate whether s-GFAP could be used as a marker of brain damage and outcome after aSAH.

METHODS

Serum samples were obtained on a regular basis from 116 adults during a 2-week period after aSAH and analyzed using an enzyme-linked immunosorbent assay. The World Federation of Neurological Surgeons scale was used for neurological evaluation. Outcome was assessed after 1 year and categorized according to the Extended Glasgow Outcome Scale.

RESULTS

Increased s-GFAP levels were seen in 81 of the 116 patients. Maximum s-GFAP correlated with World Federation of Neurological Surgeons scale on arrival and on days 10 to 15 (r=0.37, P<0.001 and r=0.47, P<0.001, respectively). Furthermore, maximum s-GFAP levels were increased in the patient group with radiological signs of focal lesions acute or at 1 year, compared with the group without focal lesions (P<0.001 in both comparisons). Patients with secondary events (re-bleeding or ischemia) reached maximum levels later in the series and both maximum and final s-GFAP levels increased compared with the levels in patients without secondary events (P<0.001 in all 3 comparisons). Finally, maximum s-GFAP correlated with outcome (r=-0.48, P<0.001) and s-GFAP was an independent predictor of dichotomized outcome.

CONCLUSIONS

s-GFAP provides information about brain injury severity and outcome after aSAH, which can be useful as a complement to clinical data.