Increases of neuron-specific enolase, S-100 protein, creatine kinase and creatine kinase BB isoenzyme in CSF following intraventricular catheter implantation

Concordance of Alzheimer's Disease-Related Biomarkers Between Intraventricular and Lumbar Cerebrospinal Fluid in Idiopathic Normal Pressure Hydrocephalus

BACKGROUND

Alzheimer's disease cerebrospinal fluid (CSF) biomarkers amyloid-β 1-42 (Aβ42), total tau (T-tau), and phosphorylated tau 181 (P-tau181) are widely used. However, concentration gradient of these biomarkers between intraventricular (V-CSF) and lumbar CSF (L-CSF) has been demonstrated in idiopathic normal pressure hydrocephalus (iNPH), potentially affecting clinical utility.

OBJECTIVE

Here we aim to provide conversion factors for clinical and research use between V-CSF and L-CSF.

METHODS

Altogether 138 iNPH patients participated. L-CSF samples were obtained prior to shunt surgery. Intraoperative V-CSF samples were obtained from 97 patients. Post-operative follow-up L- and V-CSF (shunt reservoir) samples of 41 patients were obtained 1-73 months after surgery and then after 3, 6, and 18 months. CSF concentrations of Aβ42, T-tau, and P-tau181 were analyzed using commercial ELISA assays.

RESULTS

Preoperative L-CSF Aβ42, T-tau, and P-tau181 correlated to intraoperative V-CSF (ρ= 0.34-0.55, p < 0.001). Strong correlations were seen between postoperative L- and V-CSF for all biomarkers in every follow-up sampling point (ρs Aβ42: 0.77-0.88, T-tau: 0.91-0.94, P-tau181: 0.94-0.96, p < 0.0001). Regression equations were determined for intraoperative V- and preoperative L-CSF (Aβ42: V-CSF = 185+0.34*L-CSF, T-tau: Ln(V-CSF) = 3.11+0.49*Ln(L-CSF), P-tau181: V-CSF = 8.2+0.51*L-CSF), and for postoperative V- and L-CSF (Aβ42: V-CSF = 86.7+0.75*L-CSF, T-tau: V-CSF = 86.9+0.62*L-CSF, P-tau181: V-CSF = 2.6+0.74*L-CSF).

CONCLUSION

Aβ42, T-tau, and P-tau181 correlate linearly in-between V- and L-CSF, even stronger after CSF shunt surgery. Equations presented here, provide a novel tool to use V-CSF for diagnostic and prognostic entities relying on the L-CSF concentrations and can be applicable to clinical use when L-CSF samples are not available or less invasively obtained shunt reservoir samples should be interpreted.

Time Trends of Cerebrospinal Fluid Biomarkers of Neurodegeneration in Idiopathic Normal Pressure Hydrocephalus

BACKGROUND

Longitudinal changes in cerebrospinal fluid (CSF) biomarkers are seldom studied. Furthermore, data on biomarker gradient between lumbar (L-) and ventricular (V-) compartments seems to be discordant.

OBJECTIVE

To examine alteration of CSF biomarkers reflecting Alzheimer's disease (AD)-related amyloid-β (Aβ) aggregation, tau pathology, neurodegeneration, and early synaptic degeneration by CSF shunt surgery in idiopathic normal pressure hydrocephalus (iNPH) in relation to AD-related changes in brain biopsy. In addition, biomarker levels in L- and V-CSF were compared.

METHODS

L-CSF was collected prior to shunt placement and, together with V-CSF, 3-73 months after surgery. Thereafter, additional CSF sampling took place at 3, 6, and 18 months after the baseline sample from 26 iNPH patients with confirmed Aβ plaques in frontal cortical brain biopsy and 13 iNPH patients without Aβ pathology. CSF Amyloid-β42 (Aβ42), total tau (T-tau), phosphorylated tau (P-tau181), neurofilament light (NFL), and neurogranin (NRGN) were analyzed with customized ELISAs.

RESULTS

All biomarkers but Aβ42 increased notably by 140-810% in L-CSF after CSF diversion and then stabilized. Aβ42 instead showed divergent longitudinal decrease between Aβ-positive and -negative patients in L-CSF, and thereafter increase in Aβ-negative iNPH patients in both L- and V-CSF. All five biomarkers correlated highly between V-CSF and L-CSF (Aβ42 R = 0.87, T-tau R = 0.83, P-tau R = 0.92, NFL R = 0.94, NRGN R = 0.9; all p < 0.0001) but were systematically lower in V-CSF (Aβ42 14 %, T-tau 22%, P-tau 20%, NFL 32%, NRGN 19%). With APOE genotype-grouping, only Aβ42 showed higher concentration in non-carriers of allele ɛ4.

CONCLUSION

Longitudinal follow up shows that after an initial post-surgery increase, T-tau, P-tau, and NRGN are stable in iNPH patients regardless of brain biopsy Aβ pathology, while NFL normalized toward its pre-shunt levels. Aβ42 as biomarker seems to be the least affected by the surgical procedure or shunt and may be the best predictor of AD risk in iNPH patients. All biomarker concentrations were lower in V- than L-CSF yet showing strong correlations.

Time-dependent uptake and trafficking of vesicles capturing extracellular S100B in cultured rat astrocytes

Astrocytes, the most heterogeneous glial cells in the central nervous system, contribute to brain homeostasis, by regulating a myriad of functions, including the clearance of extracellular debris. When cells are damaged, cytoplasmic proteins may exit into the extracellular space. One such protein is S100B, which may exert toxic effects on neighboring cells unless it is removed from the extracellular space, but the mechanisms of this clearance are poorly understood. By using time-lapse confocal microscopy and fluorescently labeled S100B (S100B-Alexa⁴⁸⁸ ) and fluorescent dextran (Dextran⁵⁴⁶ ), a fluid phase uptake marker, we examined the uptake of fluorescently labeled S100B-Alexa⁴⁸⁸ from extracellular space and monitored trafficking of vesicles that internalized S100B-Alexa⁴⁸⁸ . Initially, S100B-Alexa⁴⁸⁸ and Dextran⁵⁴⁶ internalized with distinct rates into different endocytotic vesicles; S100B-Alexa⁴⁸⁸ internalized into smaller vesicles than Dextran⁵⁴⁶ . At a later stage, S100B-Alexa⁴⁸⁸ -positive vesicles substantially co-localized with Dextran⁵⁴⁶ -positive endolysosomes and with acidic LysoTracker-positive vesicles. Cell treatment with anti-receptor for advanced glycation end products (RAGE) antibody, which binds to RAGE, a 'scavenger receptor', partially inhibited uptake of S100B-Alexa⁴⁸⁸ , but not of Dextran⁵⁴⁶ . The dynamin inhibitor dynole 34-2 inhibited internalization of both fluorescent probes. Directional mobility of S100B-Alexa⁴⁸⁸ -positive vesicles increased over time and was inhibited by ATP stimulation, an agent that increases cytosolic free calcium concentration ([Ca²⁺ ]_i ). We conclude that astrocytes exhibit RAGE- and dynamin-dependent vesicular mechanism to efficiently remove S100B from the extracellular space. If a similar process occurs in vivo, astroglia may mitigate the toxic effects of extracellular S100B by this process under pathophysiologic conditions. This study reveals the vesicular clearance mechanism of extracellular S100B in astrocytes. Initially, fluorescent S100B internalizes into smaller endocytotic vesicles than dextran molecules. At a later stage, both probes co-localize within endolysosomes. S100B internalization is both dynamin- and RAGE-dependent, whereas dextran internalization is dependent on dynamin. Vesicle internalization likely mitigates the toxic effects of extracellular S100B and other waste products.

The neonatal levels of TSB, NSE and CK-BB in autism spectrum disorder from Southern China

Background" Autism spectrum disorder (ASD) is a serious neurodevelopmental disorder that impairs a child's ability to communicate with others. It also includes restricted repetitive behaviors, interests and activities. Symptoms manifest before the age of 3. In the previous studies, we found structural abnormalities of the temporal lobe cortex. High spine densities were most commonly found in ASD subjects with lower levels of cognitive functioning. In the present study, we retrospectively analyzed medical records in relation to the neonatal levels of total serum bilirubin (TSB), neuron-specific enolase (NSE), creatine kinase brain band isoenzyme (CK-BB), and neonatal behavior in ASD patients from Southern China.

METHODS

A total of 80 patients with ASD (ASD group) were screened for this retrospective study. Among them, 34 were low-functioning ASD (L-ASD group) and 46 were high-functioning ASD (H-ASD group). Identification of the ASD cases was confirmed with a Revised Autism Diagnostic Inventory. For comparison with ASD cases, 80 normal neonates (control group) were selected from the same period. Biochemical parameters, including TSB, NSE and CK-BB in the neonatal period and medical records on neonatal behavior were collected.

RESULTS

The levels of serum TSB, NSE and CK-BB in the ASD group were significantly higher when compared with those from the control group (P < 0.01, or P < 0.05). The amounts of serum TSB, NSE and CK-BB in the L-ASD group were significantly higher when compared with those in the H-ASD group (P < 0.01, or P < 0.05). The Neonatal Behavioral Assessment Scale (NBAS) scores in the ASD group were significantly lower than that in the control group (P < 0.05). Likewise, the NBAS scores in the L-ASD group were significantly lower than that in the H-ASD group (P < 0.05). There was no association between serum TSB, NSE, CK-BB and NBAS scores (P > 0.05) in the ASD group.

CONCLUSIONS

The neonatal levels of TSB, NSE and CK-BB in ASD from Southern China were significantly higher than those of healthy controls. These findings need to be investigated thoroughly by future studies with large sample.

A Role of Serum-Based Neuronal and Glial Markers as Potential Predictors for Distinguishing Severity and Related Outcomes in Traumatic Brain Injury

Objective

Optimal treatment decision and estimation of the prognosis in traumatic brain injury (TBI) is currently based on demographic and clinical predictors. But sometimes, there are limitations in these factors. In this study, we analyzed three central nervous system biomarkers in TBI patients, will discuss the roles and clinical applications of biomarkers in TBI.

Methods

From July on 2013 to August on 2014, a total of 45 patients were included. The serum was obtained at the time of hospital admission, and biomarkers were extracted with centrifugal process. It was analyzed for the level of S-100 beta (S100B), glial fibrillary acidic protein (GFAP), and ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1).

Results

This study included 33 males and 12 females with a mean age of 58.5 (19-84) years. TBI patients were classified into two groups. Group A was severe TBI with Glasgow Coma Scale (GCS) score 3-5 and Group B was mild TBI with GCS score 13-15. The median serum concentration of S100B, GFAP, and UCH-L1 in severe TBI were raised 5.1 fold, 5.5 fold, and 439.1 fold compared to mild injury, respectively. The serum levels of these markers correlated significantly with the injury severity and clinical outcome (p<0.001). Increased level of markers was strongly predicted poor outcomes.

Conclusion

S100B, GFAP, and UCH-L1 serum level of were significantly increased in TBI according to severity and associated clinical outcomes. Biomarkers have potential utility as diagnostic, prognostic, and therapeutic adjuncts in the setting of TBI.

Biokinetic analysis of ubiquitin C-terminal hydrolase-L1 (UCH-L1) in severe traumatic brain injury patient biofluids

Ubiquitin C-terminal hydrolase-L1 (UCH-L1) is a neuron-specific enzyme that has been identified as a potential biomarker of traumatic brain injury (TBI). The study objectives were to determine UCH-L1 exposure and kinetic metrics, determine correlations between biofluids, and assess outcome correlations in severe TBI patients. Data were analyzed from a prospective, multicenter study of severe TBI (Glasgow Coma Scale [GCS] score ≤ 8). Cerebrospinal fluid (CSF) and serum data from samples taken every 6 h after injury were analyzed by enzyme-linked immunosorbent assay (ELISA). UCH-L1 CSF and serum data from 59 patients were used to determine biofluid correlations. Serum samples from 86 patients and CSF from 59 patients were used to determine outcome correlations. Exposure and kinetic metrics were evaluated acutely and up to 7 days post-injury and compared to mortality at 3 months. There were significant correlations between UCH-L1 CSF and serum median concentrations (r(s)=0.59, p<0.001), AUC (r(s)=0.3, p=0.027), Tmax (r(s)=0.68, p<0.001), and MRT (r(s)=0.65, p<0.001). Outcome analysis showed significant increases in median serum AUC (2016 versus 265 ng/mL*min, p=0.006), and Cmax (2 versus 0.4 ng/mL, p=0.003), and a shorter Tmax (8 versus 19 h, p=0.04) in those who died versus those who survived, respectively. In the first 24 h after injury, there was a statistically significant acute increase in CSF and serum median Cmax((0-24h)) in those who died. This study shows a significant correlation between UCH-L1 CSF and serum median concentrations and biokinetics in severe TBI patients, and relationships with clinical outcome were detected.

Serum markers of cerebral ischemia

Rapid diagnosis and management of stroke patients is becoming increasingly important with the emergence of new interventional strategies for acute cerebral ischemia. A biochemical surrogate of cerebral ischemia, rapidly detectable in the serum before radiological diagnosis, might have clinical utility in the setting of acute stroke, high-risk cardiovascular procedures, and subarachnoid hemorrhage. Such a marker might also aid in the neurological prognosis of anoxic brain injury. Several serum markers have been evaluated in acute cerebral ischemia. These include neuronal enzymes such as neuron-specific enolase; markers of glial injury and activation, such as protein S100beta; and mediators of inflammation, such as interleukin-6. The clinical and preclinical data supporting the use of these biochemical surrogates of cerebral ischemia are reviewed.

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.

Reliability of S100B in predicting severity of central nervous system injury

S100B is a protein biomarker that reflects CNS injury. It can be measured in the CSF or serum with readily available immunoassay kits. The excellent sensitivity of S100B has enabled it to confirm the existence of subtle brain injury in patients with mild head trauma, strokes, and after successful resuscitation from cardiopulmonary arrest. The extent of S100B elevation has been found to be useful in predicting clinical outcome after brain injury. Elevations of S100B above certain threshold levels might be able to reliably predict brain death or mortality. A normal S100B level reliably predicts the absence of significant CNS injury. The specificity of S100B levels as a reflection of CNS injury is compromised by the findings that extra-cranial injuries can lead to elevations in the absence of brain injury. This potential problem can most likely be avoided by measuring serial S100B levels along with other biomarkers and carefully noting peripheral injuries. Serum markers GFAP and NSE are both more specific for CNS injury and have little to no extra-cranial sources. Sustained elevations of S100B over 24 h along with elevations of GFAP and NSE can more reliably predict the extent of brain injury and clinical outcomes. In the future, S100B measurements might reliably predict secondary brain injury and enable physicians to initiate therapeutic interventions in a timelier manner. S100B levels have been shown to rise hours to days before changes in ICP, neurological examinations, and neuroimaging tests. S100B levels may also be used to monitor the efficacy of treatments.

Biomarkers in chronic adult hydrocephalus

Awareness of the importance of chronic adult hydrocephalus has been raised again with the recent emergence of epidemiological studies. It is estimated that between 5 and 10% of patients suffering from dementia might, in fact, have chronic hydrocephalus. Although, surgical diversion of the cerebrospinal fluid (CSF) represents the only known procedure able to treat the symptoms of this condition, the selection of surgical patients has always been problematic. In the last 40 years, we have become wiser in using appropriate diagnostic tests for the selection of these patients; however, the area of biological markers has so far been overlooked in this condition, in contrast to that for other neurodegenerative disorders and dementias. Biomarkers are biological substances that may be used to indicate either the onset or the presence, and the progression of a clinical condition, being closely linked to its pathophysiology. In such a setting they might assist in the more appropriate selection of patients for shunt surgery. In this article, we have reviewed research carried out in the last 25 years regarding the identification of serum and CSF biomarkers for chronic hydrocephalus, discussed the potential for each one, and finally discussed the limitations for use, as well as future directions and possibilities in this field. It is concluded that tumour-necrosis factor, tau protein, lactate, sulfatide and neurofilament triple protein are the most promising CSF markers for chronic hydrocephalus. At present however, none of these meet the criteria required to justify a change clinical practice. In the future, collaborative multi-centre projects will be needed to obtain more substantial data that overcome the problems that arise from small individual and uncoordinated studies.

S-100B and NSE: markers of initial impact of subarachnoid haemorrhage and their relation to vasospasm and outcome

S100-B and neuron specific enolase (NSE) are known predictors of outcome in head injured and stroke patients. This study was conducted to test the hypothesis that S-100B and NSE can predict the development of vasospasm and outcome within the first 3 days after subarachnoid haemorrhage (SAH). Fifty-one SAH patients (mean age 51+/-11 years, male : female ratio 1.0 : 1.6, mean World Federation of Neurological Surgeons [WFNS] Grade 3+/-1.5) were included in the study. S100-B and NSE were recorded in venous blood across the first 3 days post-SAH. Vasospasm was diagnosed if mean blood flow velocity of the middle cerebral artery was greater than 120 cm/s and Lindegaard ratio >3. Glasgow Outcome Score (GOS) and cranial CT scans were recorded at 6 months. Normal, intermediate and high S-100B values were seen in 24%, 51% and 25% of patients, respectively. In patients with S-100B>1 microg/L, Fisher Grade 4 and WFNS 4-5 were both seen in 77% of cases. S-100B was significantly higher in those patients who did not develop vasospasm. In addition, S-100B values were significantly higher in those patients who died than in those with unfavourable or favourable outcome. NSE was normal, intermediate and high in 82%, 8% and 10% of patients, respectively. Patients with WFNS 4-5 and/or Fisher Grade 4 had significantly higher NSE values than all others. Across the first 3 days after SAH, measuring S-100B is useful to predict outcome and vasospasm.

Increased GFAP and S100beta but not NSE serum levels after subarachnoid haemorrhage are associated with clinical severity

Assessment of initial disease severity after subarachnoid haemorrhage (SAH) remains difficult. The objective of the study is to identify biochemical markers of brain damage in peripheral blood after SAH. Hospital admission S100beta, glial fibrillary acidic protein (GFAP) and neuron-specific enolase (NSE) serum levels were analysed in 67 patients with SAH. Disease severity was determined by using the World Federation of Neurological Surgeons (WFNS) scale and the Fisher CT (computerized tomography) grading scale. Mean astroglial serum concentrations taken at hospital admission were increased (S100beta 2.8-fold and GFAP 1.8-fold) compared with the upper limit of normal laboratory reference values (P95). The mean NSE concentration was within normal limits. S100beta (P < 0.001) and GFAP (P =0.011) but not NSE levels were higher in patients who were in coma at the time of hospital admission compared with patients who were not. Similarly S100beta and GFAP but not NSE serum levels increased with higher WFNS scores, raised intracranial pressure and higher CT Fisher grade scores. Concerning the location of the aneurysm, S100beta and GFAP serum levels were within normal limits after a perimesencephalic type of haemorrhage and significantly increased after aneurysmal type SAH. Increased glial (S100beta and GFAP) but not neuronal (NSE) protein serum concentrations are found after SAH, associated to the clinical severity of the initial injury.

Axonal pathology in subarachnoid and intracerebral hemorrhage

Electrically active axons degenerate in the presence of nitric oxide (NO) in vitro. High CSF NO concentrations have been observed in patients with hemorrhagic brain injury such as subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH). This study investigated the evidence for axonal injury in SAH and ICH and related this to CSF NO levels. In this study, neurofilament phosphoforms (NfH(SMI34), NfH(SMI35), NfH(SMI38), NfH(SMI310)), surrogate markers for axonal injury, and NO metabolites (nitrate, nitrite = NOx) were measured by ELISA in cerebrospinal fluid (CSF) from patients with SAH and ICH and from a group of controls. Injury severity was classified using the Glasgow Coma Scale, and survival was used as the outcome measure. Compared to the control group, a higher proportion of patients with SAH and ICH had elevated NfH(SMI34) levels from day 0 to day 6 (p < 0.001), elevated NfH(SMI35) levels from day 1 to 6 (p < 0.001), and elevated NfH(SMI310) levels at day 0, 1, 4, and 6 (p < 0.001). The NOx levels were higher in the SAH and ICH patients than in the controls (p < 0.05) and distinguished the non-survivors from the survivors (p < 0.05). No direct correlation was found for NOx with any of the NfH phosphoforms. This study provides evidence for primary and secondary axonal injury in patients with SAH and ICH, with non-survivors also having higher NOx levels. CSF NfH phosphoforms might emerge as a putative surrogate marker for monitoring the development for secondary axonal degeneration in neurocritical care and guiding targeted neuroprotective strategies.

Glial and neuronal proteins in serum predict outcome after severe traumatic brain injury

OBJECTIVE

To study the ability of glial (glial fibrillary acidic protein [GFAP] and S100b) and neuronal (neuron specific enolase [NSE]) protein levels in peripheral blood to predict outcome after severe traumatic brain injury.

METHODS

Eighty-five patients with severe traumatic brain injury (admission Glasgow Coma Score [GCS] < or = 8) were included. Blood samples taken at the time of hospital admission were analyzed for S100b, GFAP, and NSE. Data collected included demographic and clinical variables. Outcome was assessed using the Glasgow Outcome Scale (GOS) at 6 months post injury.

RESULTS

The median serum levels of S100b, GFAP, and NSE were raised 18.3 fold (S100b), 4.6 fold (GFAP), and twofold (NSE) compared to normal reference values. S100b, GFAP, and NSE serum levels correlated significantly with the injury severity score and CT findings but not with age, sex, or GCS. S100b, GFAP, and NSE levels were significantly higher in patients who died or had a poor outcome 6 months post injury than in those who were alive or had good outcome. S100b level >1.13 microg/L was the strongest predictor of death with 100% discrimination, but GFAP (>1.5 microg/L) and NSE (>21.7 microg/L) levels also strongly predicted death (adjusted odds ratios 5.82 [for GFAP] and 3.91 [for NSE]). S100b, GFAP, and NSE all strongly predicted poor outcome (adjusted odds ratios 5.12 [S100b], 8.82 [GFAP], and 3.95 [NSE]).

CONCLUSIONS

These results suggest that determination of serum levels of glial and neuronal proteins may add to the clinical assessment of the primary damage and prediction of outcome after severe traumatic brain injury.

Biochemical markers of brain injury: could they be used as diagnostic adjuncts in cases of inflicted traumatic brain injury?

Child abuse is the leading cause of serious traumatic brain injury (TBI) in infants and young children (Billmire & Myers, 1985; Bruce & Zimmerman, 1989). The incidence of serious or fatal inflicted traumatic brain injury (iTBI) in children < 1 year of age is approximately 1 in 3,300 ( Keenan et al., 2003); since many cases of iTBI are of mild or moderate severity, the incidence is probably significantly higher. Even at an incidence of 1 in 3,300, iTBI is as common as the incidence of cystic fibrosis (CF), the most common genetic recessive disease in the Caucasian population. Proper diagnosis of iTBI is difficult even for experienced and astute physicians because its presentation can be subtle and important historical data are often lacking. As a result, misdiagnosis is common and can have catastrophic medical consequences for patients and significant financial consequences for society ( Ewing-Cobbs et al., 1998; Jenny, Hymel, Pitzen, Reinert, & Hay, 1999). Unlike CF for which there are several well established screening tests, there are currently no diagnostic adjuncts to help physicians screen for possible iTBI.

Ventricular tapping seems to have no influence on S-100B and NSE serum concentrations

Serum markers, e.show $132#g., the protein S-100B and neuron-specific enolase (NSE), are recognized to give additional information about the extension and prognosis of brain damage. In some of these patients it is necessary to insert a ventricular drain. Whether the cannulation of the ventricle falsifies the serum concentrations of these markers is unknown. The aim of this study was to get further information in this field. In this prospective study we included 19 patients. All patients underwent ventricular tapping and insertion of a ventricular drain. Serum samples for estimation of S-100B and NSE were collected before, directly after and 6 h after insertion. In addition we investigated the cerebrospinal fluid (CSF) directly after and 6 h after insertion. All patients but one showed no significantly increased S-100B or NSE serum concentration after insertion of the drainage. The concentrations in the CSF were significantly higher. One patient showed increasing concentrations of the markers in all samples reflecting ongoing brain damage. The serum values of S-100B and NSE seem not to be falsified by insertion of a ventricular drain. Therefore the prognostic value of these serum markers seems to be preserved despite the surgical manipulation.

Impulse noise transiently increased the permeability of nerve and glial cell membranes, an effect accentuated by a recent brain injury

A single exposure to intense impulse noise may cause diffuse brain injury, revealed by increased expression of immediate early gene products, transiently altered distribution of neurofilaments, accumulation of beta-amyloid precursor protein, apoptosis, and gliosis. Neither hemorrage nor any gross structural damage are seen. The present study focused on whether impulse noise exposure increased the permeability of nerve and glial cell membranes to proteins. Also, we investigated whether a preceding, minor focal surgical brain lesion accentuated the leakage of cytosolic proteins. Anaesthetized rats were exposed to a single impulse noise at either 199 or 202 dB for 2 milliseconds. Transiently elevated levels of the cellular protein neuron specific enolase (NSE) and the glial cytoplasmic protein S-100 were recorded in the cerebrospinal fluid (CSF) during the first hours after the exposure to 202 dB. A surgical brain injury, induced the day before the exposure to the impulse noise, was associated with significantly increased concentrations of both markers in the CSF. It is concluded that intense impulse noise damages both nerve and glial cells, an effect aggravated by a preexisting surgical lesion. The impulse of the shock wave, i.e. the pressure integrated over time, is likely to be the injurious mechanism. The abnormal membrane permeability and the associated cytoskeletal changes may initiate events, which eventually result in a progressive diffuse brain injury.

Detection of traumatic brain injury with magnetic resonance imaging and S-100B protein in children, despite normal computed tomography of the brain

OBJECTIVE

The objective of this study was to obtain data to further define the extent of traumatic brain injury by using S-100B protein and standard noncontrast magnetic resonance imaging with added fluid-attenuated inversion recovery (FLAIR) and gradient echo sequence in children with normal head computed tomography.

DESIGN

Pilot, single cohort, prospective, clinical diagnostic study.

SETTING

Pediatric intensive care and intermediate care unit in a tertiary care children's hospital.

PATIENTS

Children ages 5-18 yrs who sustained traumatic brain injury, had a negative computed tomography of the brain, and were admitted to hospital were eligible for enrollment.

INTERVENTIONS

Two blood samples were drawn for S-100B protein analysis: the first (t-1) as soon as possible or close to 6 hrs of injury and the second (t-2) close to 12 hrs from the time of injury. A magnetic resonance image of the brain was obtained within 96 hrs of injury.

MEASUREMENTS AND MAIN RESULTS

Seven of 17 patients (41%) had positive magnetic resonance image. Of the seven patients with positive magnetic resonance image, 100% (seven of seven) had a positive magnetic resonance image with FLAIR sequence, 85% (six of seven) with axial T2 sequence and 50% (three of six) with gradient echo sequence. There was no statistically significant difference in S-100B protein concentrations in patients with a positive magnetic resonance image (n = 7) and those with a negative magnetic resonance image (n = 10; p =.40 at t-1 and p =.13 at t-2). The concentration of S-100B protein was statistically significantly higher in patients with head and other bodily injury (n = 9) compared with isolated head injury (n = 6; p =.018 at t-1 and p =.025 at t-2). Patients with a positive magnetic resonance image had a lower Glasgow Coma Scale score and longer duration of hospital stay.

CONCLUSIONS

Magnetic resonance imaging seems to be a useful modality to better define the spectrum of brain injury in children with mild head trauma. The addition of S-100B protein measurement does not seem to be useful in this setting.

S100B in brain damage and neurodegeneration

S100B is a calcium-binding peptide produced mainly by astrocytes that exert paracrine and autocrine effects on neurons and glia. Some knowledge has been acquired from in vitro and in vivo animal experiments to understand S100B's roles in cellular energy metabolism, cytoskeleton modification, cell proliferation, and differentiation. Also, insights have been gained regarding the interaction between S100B and the cerebral immune system, and the regulation of S100B activity through serotonergic transmission. Secreted glial S100B exerts trophic or toxic effects depending on its concentration. At nanomolar concentrations, S100B stimulates neurite outgrowth and enhances survival of neurons during development. In contrast, micromolar levels of extracellular S100B in vitro stimulate the expression of proinflammatory cytokines and induce apoptosis. In animal studies, changes in the cerebral concentration of S100B cause behavioral disturbances and cognitive deficits. In humans, increased S100B has been detected with various clinical conditions. Brain trauma and ischemia is associated with increased S100B concentrations, probably due to the destruction of astrocytes. In neurodegenerative, inflammatory and psychiatric diseases, increased S100B levels may be caused by secreted S100B or release from damaged astrocytes. This review summarizes published findings on S100B regarding human brain damage and neurodegeneration. Findings from in vitro and in vivo animal experiments relevant for human neurodegenerative diseases and brain damage are reviewed together with the results of studies on traumatic, ischemic, and inflammatory brain damage as well as neurodegenerative and psychiatric disorders. Methodological problems are discussed and perspectives for future research are outlined.

Nerve tissue protein S-100 and neurone-specific enolase concentrations in cerebrospinal fluid and blood during carotid endarterectomy

Nerve tissue protein S-100 and neurone-specific enolase levels in serum were studied in 10 patients before, during and for 2 days after elective carotid endarterectomy performed under general anaesthesia and using a Javid Shunt. In six patients, simultaneous cerebrospinal fluid samples were also obtained. Serum nerve tissue protein S-100 was normal throughout the operation, but in one patient with severe hypertension, levels increased to 1.38 microg. l-1 at 1 h postoperatively. Two patients showed an increase in cerebrospinal fluid nerve tissue protein S-100 during clamping: these patients also had neurological deficits at 6 months. Serum neurone-specific enolase increased from 5.8 to 9.3 microg.l-1 during shunting while cerebrospinal fluid neurone-specific enolase did not change. Uncomplicated carotid endarterectomy does not produce cerebral damage as measured by serum nerve tissue protein S-100; cerebrospinal fluid nerve tissue protein S-100 may be more sensitive for minor cerebral damage. Neurone-specific enolase appeared to be nonspecific. The lack of correlation between the neuroproteins may need to be explained before relying on these simple assays as diagnostic indicators of cerebral ischaemia.

Cisternal S100 protein and neuron-specific enolase are elevated and site-specific markers in intractable temporal lobe epilepsy

In the brain, S100 protein and neuron-specific enolase (NSE) are mainly found in glial cells and neurons, respectively. We investigated concentrations of S100 protein and NSE in cisternal cerebrospinal fluid obtained during implantation of foramen ovale electrodes in eight patients with temporal lobe epilepsy (TLE). In addition, the meningeal markers cystatin-C and beta-trace as well as total protein were measured. Patients with trigeminal neuralgia (TN) undergoing glycerol rhizotomy served as controls. S100 protein and NSE levels ipsilateral to the site of seizure onset were significantly higher than in TN. Contralateral TLE values were also markedly but not significantly elevated. The meningeal markers cystatin-C and beta-trace protein as well as total protein did not differ in TLE and TN. We conclude that interictal temporal lobe dysfunction corresponds with neuronal and glial marker elevations in the extracellular space and that site-specific elevations may predict the site of seizure origin biochemically.

Neuron-specific enolase levels in the cerebrospinal fluid of neurologically healthy children

Levels of neuron-specific enolase (NSE) levels in the cerebrospinal fluid (CSF) of children without neurological disease were assessed. CSF samples were obtained from 37 subjects aged between 1 month and 13 years. All subjects had undergone lumbar puncture for diagnostic purposes, and were subsequently shown not to be suffering any form of neurological disease. NSE levels in CSF were determined by an enzyme immunoassay method. NSE level ranged from below the detection limit to 4.8 ng/ml (1.52+/-1.01 ng/ml). The present results may be useful as a basis for defining reference levels of NSE in CSF in post-neonatal children.

S-100 serum levels after minor and major head injury

BACKGROUND

S-100, a protein of astroglial cells, is described as a marker for central nervous system damage. The aim of this study was to evaluate whether the marker could give information about the severity and possibility of functional recovery after minor and severe head injury.

METHODS

Thirty patients after severe head injury (Glasgow Coma Scale score < 9) and 11 patients after minor head injury (Glasgow Coma Scale score > 12) were included. In each case, blood samples were drawn within 6 hours after injury. Outcome was estimated at hospital discharge using the Glasgow Outcome Scale.

RESULTS

All patients who sustained minor head injury had reached a favorable outcome by the time they were discharged from the hospital. Their mean S-100 serum level was 0.35 microg/L. Patients who sustained severe head injury and were classified as having an unfavorable outcome (31%) showed a mean serum concentration of 4.9 microg/L, whereas patients classified as having a favorable outcome (69%) had a mean S-100 level of 1.2 microg/L. All groups differed significantly (p < 0.05).

CONCLUSION

S-100 appears to be a promising marker for the severity of head injury and neuronal damage.

Comparison of serial S-100 and NSE serum measurements after severe head injury

We investigated the time course of neuron specific enolase (NSE) and S-100 protein after severe head injury in correlation to outcome. We included 30 patients (GCS < 9), who had been admitted within 5 hours after injury, in a prospective study. Blood samples were taken on admission, 6, 12, and 24 hours and every 24 hours up to the fifth day after injury. The outcome was estimated on discharge using the Glasgow Outcome Scale. 70% reached a good outcome. All concentrations of NSE and 83% of the S-100 samples were elevated concerning the first probe (30.2 micrograms/l NSE mean and 2.6 micrograms/l S-100 mean). Patients with bad outcome had an NSE concentration of 38 micrograms/l (mean) compared with 26.9 micrograms/l (mean) in patients with good outcome. Patients with bad outcome had an S-100 concentration of 4.9 micrograms/l (mean) compared with 1.7 micrograms/l (mean) in patients with good outcome (p < 0.05). The mean values of NSE and S-100 decreased during the first 5 days. Four patients with increasing intracranial pressure showed a quick increasing concentration of NSE, in two patients the S-100 level showed a slower rise. The NSE serum levels did not correlate with intracranial pressure values. Our results show that the first serum concentration of S-100 seems to be predictive for outcome after severe head injury.

A sandwich enzyme immunoassay for brain S-100 protein and its forensic application

A sensitive sandwich enzyme immunoassay for identification of brain S-100 protein in blood or bloodstains containing brain tissue is described. A polystyrene ball coated with rabbit anti-S-100 protein IgG was incubated with human S-100 protein, and then with anti-S-100 Fab'-peroxidase conjugate. Peroxidase activity bound to the polystyrene ball was assayed by fluorometry using 3-(4-hydroxyphenyl)propionic acid as the hydrogen donor. The detection limit of human S-100 protein was 0.6 pg (30 amol) per assay tube. The cross-reaction of this sandwich enzyme immunoassay to other organs was approximately 1/100 or less. Antigenic activity of S-100 protein in bloodstains containing brain extracts was detectable after storage for 36 days at room temperature. The ratio of S-100 protein to total protein (ng/mg) in bloodstains when brain tissue was mixed with normal human blood at concentrations of 5-500 mg/ml was approximately 100-fold those of other samples (liver, heart, intestine, and skeletal muscle). These results indicated that bloodstains mixed with brain tissue were clearly distinguishable from others. Thus, in forensic practice, measurement of S-100 protein or the ratio of S-100 protein to total protein is useful to identify blood and bloodstains containing brain tissue.

beta-Amyloid regulates gene expression of glial trophic substance S100 beta in C6 glioma and primary astrocyte cultures

S100 beta, a calcium-binding protein synthesized by CNS astrocytes, has trophic effects in vitro (neurite extension and glial proliferation). In Alzheimer's disease and Down's syndrome, severely afflicted brain regions exhibit up to 20-fold higher levels of S100 beta protein, and astrocytes surrounding neuritic plaques exhibit highly elevated levels of S100 beta immunostaining. A major constituent of plaques, beta-amyloid, has been reported to have neurotoxic and neurotrophic effects in vitro. In our study we examined the responses of CNS glia to beta-amyloid. C6 glioma cells and primary rat astrocyte cultures were treated with beta A(1-40) peptide at doses up to 1 microM. Weak mitogenic activity, measured by [3H]thymidine incorporation, was observed. Northern blot analysis revealed increases of S100 beta mRNA within 24 h in a dose-dependent manner. Nuclear run-off transcription assays showed that beta A(1-40) specifically induced new synthesis of S100 beta mRNA in cells maintained in serum, but under serum-free conditions, there was a general elevation of several mRNA species. Corresponding increases of S100 beta protein synthesis were observed by immunoprecipitation of 35S-labeled cellular proteins. To evaluate whether this effect of beta-amyloid was mediated via neurokinin receptors or by calcium fluxes, various agonists and antagonists were tested and found to be ineffective at stimulating S100 beta synthesis. In sum, these in vitro data suggest that in neuropathological conditions, beta-amyloid itself is an agent which may provoke chronic gliosis and the production of trophic substances by astrocytes.

Measurement of S-100 protein in human blood and cerebrospinal fluid: analytical method and preliminary clinical results

An immunofluorometric sandwich assay for determination of S-100 protein in cerebrospinal fluid (CSF) and blood is described. The lower detection limit was 0.015 micrograms/l of S-100 protein. Intra-assay and inter-assay imprecision (coefficients of variation, CVs) were 2.1 to 3.2% and 7.8 to 11.6%, respectively. S-100 protein recovery in cerebrospinal fluid was 94 to 103%. In blood the recovery varied from 67 to 96%, depending on blood samples used and the concentration of S-100 protein. The best recovery in blood was found using heparinized plasma. In healthy subjects 0.098 +/- 0.11 micrograms/l (mean +/- SD) of S-100 protein was detected (n = 30). In the CSF of otherwise healthy patients undergoing a myelography for lumbar pain 1.43 +/- 0.49 micrograms/l (mean +/- SD) of S-100 protein was found. Preliminary results from longitudinal studies on S-100 protein in neurosurgical patients indicate a positive correlation between S-100 protein blood levels and clinical course. Thus, the determination of S-100 protein in blood appears to be helpful in the monitoring of patients with neuronal damage.