Advances in development of biomarkers for brain damage and ischemia.

Acquired brain injury is an urgent situation that requires rapid diagnosis and treatment. Magnetic resonance imaging (MRI) and computed tomography (CT) are required for accurate diagnosis. However, these methods are costly and require substantial infrastructure and specialized staff. Circulatory biomarkers of acute brain injury may help in the management of patients with acute cerebrovascular events and prevent poor outcome and mortality. The purpose of this review is to provide an overview of the development of potential biomarkers of brain damage to increase diagnostic possibilities. For this purpose, we searched the PubMed database of studies on the diagnostic potential of brain injury biomarkers. We also accessed information from Clinicaltrials.gov to identify any clinical trials of biomarker measurements for the diagnosis of brain damage. In total, we present 41 proteins, enzymes and hormones that have been considered as biomarkers for brain injury, of which 20 have been studied in clinical trials. Several microRNAs have also emerged as potential clinical biomarkers for early diagnosis. Combining multiple biomarkers in a panel, along with other parameters, is yielding promising outcomes.

Standard versus High Cardiopulmonary Bypass Flow Rate: A Randomized Controlled Subtrial Comparing Brain Injury Biomarker Release.

OBJECTIVES: To compare brain injury biomarker release levels between two different cardiopulmonary bypass (CPB) flow rates in elective cardiac surgery and to explore differences in postoperative delirium between groups and associations between age, sex, CPB time, oxygen levels, and near-infrared spectroscopy, and biomarker levels. DESIGN: A randomized controlled substudy trial SETTING: Sahlgrenska University Hospital, Sweden PARTICIPANTS: Forty patients undergoing elective cardiac surgery with CPB INTERVENTION: Patients were assigned at random to either a standard (2.4 L/min/m2) or a high (2.9 L/min/m2) CPB flow rate. MEASUREMENTS AND MAIN RESULTS: Glial fibrillary acidic protein, neurofilament light chain, total-tau, and phosphorylated-tau217 were sampled in plasma before anesthesia induction, after 60 minutes on CPB, and at 30 minutes, 24 hours, and 72 hours post-CPB. Mixed models for repeated measures were used to analyze differences in biomarker levels between groups and to assess relationships, which showed no differences between the 2 flow rate groups. There also was no difference in the occurrence of delirium between the 2 groups. Associations were found between age and increased neurofilament light chain levels. Female sex, oxygen delivery >330 mL/min/m2, and near-infrared spectroscopy level >60% were associated with lower biomarker levels. CONCLUSIONS: An increased flow rate did not have any significant effects on biomarker levels compared to a standard flow rate. Several associations were identified between treatment characteristics and biomarker levels. No difference in delirium was seen.

Short-term mild hyperventilation on intracranial pressure, cerebral autoregulation, and oxygenation in acute brain injury patients: a prospective observational study.

Current guidelines suggest a target of partial pressure of carbon dioxide (PaCO2) of 32-35 mmHg (mild hypocapnia) as tier 2 for the management of intracranial hypertension. However, the effects of mild hyperventilation on cerebrovascular dynamics are not completely elucidated. The aim of this study is to evaluate the changes of intracranial pressure (ICP), cerebral autoregulation (measured through pressure reactivity index, PRx), and regional cerebral oxygenation (rSO2) parameters before and after induction of mild hyperventilation. Single center, observational study including patients with acute brain injury (ABI) admitted to the intensive care unit undergoing multimodal neuromonitoring and requiring titration of PaCO2 values to mild hypocapnia as tier 2 for the management of intracranial hypertension. Twenty-five patients were included in this study (40% female), median age 64.7 years (Interquartile Range, IQR = 45.9-73.2). Median Glasgow Coma Scale was 6 (IQR = 3-11). After mild hyperventilation, PaCO2 values decreased (from 42 (39-44) to 34 (32-34) mmHg, p < 0.0001), ICP and PRx significantly decreased (from 25.4 (24.1-26.4) to 17.5 (16-21.2) mmHg, p < 0.0001, and from 0.32 (0.1-0.52) to 0.12 (-0.03-0.23), p < 0.0001). rSO2 was statistically but not clinically significantly reduced (from 60% (56-64) to 59% (54-61), p < 0.0001), but the arterial component of rSO2 (ΔO2Hbi, changes in concentration of oxygenated hemoglobin of the total rSO2) decreased from 3.83 (3-6.2) µM.cm to 1.6 (0.5-3.1) µM.cm, p = 0.0001. Mild hyperventilation can reduce ICP and improve cerebral autoregulation, with minimal clinical effects on cerebral oxygenation. However, the arterial component of rSO2 was importantly reduced. Multimodal neuromonitoring is essential when titrating PaCO2 values for ICP management.

Predictive value of TCCD and regional cerebral oxygen saturation for detecting early postoperative brain injury.

OBJECTIVE: This study aims to analyze the risk factors for early postoperative brain injury in patients undergoing cardiovascular surgery and explore the predictive value of transcranial color Doppler (TCCD) and regional cerebral oxygen saturation (rSO2) for detecting early postoperative brain injury in cardiovascular surgery patients. METHODS: A total of 55 patients undergoing cardiovascular surgery with cardiopulmonary bypass in Changzhou No.2 The People's Hospital of Nanjing Medical University were included in this study. Neuron-specific enolase (NSE) concentration was measured 24 h after operation. Patients were divided into brain injury (NSE ≥ 16.3 ng/mL) and normal (0 < NSE < 16.3 ng/mL) groups according to the measured NSE concentration. The clinical outcomes between the two groups were compared, including decreased rSO2 and cerebral blood flow (as measured by TCCD) levels. The risk factors of early postoperative brain injury were analyzed by multivariate logistic regression analysis, and the significant variables were analyzed by receiver operating characteristic (ROC) analysis. RESULTS: A total of 50 patients were included in this study, with 20 patients in the brain injury group and 30 patients in the normal group. Cardiopulmonary bypass time (min) (107 ± 29 vs. 90 ± 28, P = 0.047) and aortic occlusion time (min) (111 (IQR 81-127) vs. 87 (IQR 72-116), P = 0.010) were significantly longer in the brain injury group than in the normal group. Patients in the brain injury group had greater decreased rSO2 (%) (27.0 ± 7.3 vs. 17.5 ± 6.1, P < 0.001) and cerebral blood flow (%) (44.9 (IQR 37.8-69.2) vs. 29.1 (IQR 12.0-48.2), P = 0.004) levels. Multivariate logistic regression analysis suggested that decreased rSO2 and cerebral blood flow levels, aortic occlusion time, and history of atrial fibrillation were independent risk factors for early postoperative brain injury (P < 0.05). ROC analysis reported that the best cutoff values for predicting early postoperative brain injury were 21.4% and 37.4% for decreased rSO2 and cerebral blood flow levels, respectively (P < 0.05). CONCLUSION: The decreased rSO2 and cerebral blood flow levels, aorta occlusion time, and history of atrial fibrillation were independent risk factors for early postoperative brain injury. TCCD and rSO2 could effectively monitor brain metabolism and cerebral blood flow and predict early postoperative brain injury.

Preserving Brain LPC-DHA by Plasma Supplementation Attenuates Brain Injury after Cardiac Arrest.

OBJECTIVE: Cardiac arrest (CA) is a major health burden with brain damage being a significant contributor to mortality. We found lysophosphatidylcholine (LPC), including a species containing docosahexaenoic acid (LPC-DHA), was significantly decreased in plasma post-CA, supplementation of which significantly improved neurological outcomes. The aim of this study is to understand the protective role of LPC-DHA supplementation on the brain post-CA. METHODS: We first evaluated associations between the plasma level of LPC-DHA and neurological injury and outcomes of human patients with CA. We then utilized a rat CA model and cell cultures to investigate therapeutic and mechanistic aspects of plasma LPC-DHA supplementation. RESULTS: We found that decreased plasma LPC-DHA was strongly associated with neurological outcomes and disappearance of the difference between gray and white matter in the brain after CA in human patients. In rats, the decreased plasma LPC-DHA was associated with decreased levels of brain LPC-DHA after CA, and supplementing plasma LPC-DHA normalized brain levels of LPC-DHA and alleviated neuronal cell death, activation of astrocytes, and expression of various inflammatory and mitochondrial dynamics genes. We also observed deceased severity of metabolic alterations with LPC-DHA supplementation using untargeted metabolomics analysis. Furthermore, LPC treatment showed a similar protective effect for neurons and astrocytes in mixed primary brain cell cultures. INTERPRETATION: The observed neuroprotection accompanied with normalized brain LPC-DHA level by plasma supplementation implicate the importance of preventing the decrease of brain LPC-DHA post-CA for attenuating brain injury. Furthermore, the data supports the causative role of decreased plasma LPC-DHA for brain damage after CA. ANN NEUROL 2022;91:389-403.

Large-scale informatic analysis to algorithmically identify blood biomarkers of neurological damage.

The identification of precision blood biomarkers which can accurately indicate damage to brain tissue could yield molecular diagnostics with the potential to improve how we detect and treat neurological pathologies. However, a majority of candidate blood biomarkers for neurological damage that are studied today are proteins which were arbitrarily proposed several decades before the advent of high-throughput omic techniques, and it is unclear whether they represent the best possible targets relative to the remainder of the human proteome. Here, we leveraged mRNA expression data generated from nearly 12,000 human specimens to algorithmically evaluate over 17,000 protein-coding genes in terms of their potential to produce blood biomarkers for neurological damage based on their expression profiles both across the body and within the brain. The circulating levels of proteins associated with the top-ranked genes were then measured in blood sampled from a diverse cohort of patients diagnosed with a variety of acute and chronic neurological disorders, including ischemic stroke, hemorrhagic stroke, traumatic brain injury, Alzheimer's disease, and multiple sclerosis, and evaluated for their diagnostic performance. Our analysis identifies several previously unexplored candidate blood biomarkers of neurological damage with possible clinical utility, many of which whose presence in blood is likely linked to specific cell-level pathologic processes. Furthermore, our findings also suggest that many frequently cited previously proposed blood biomarkers exhibit expression profiles which could limit their diagnostic efficacy.

Early Brain Injury and Soluble ST2 After Nontraumatic Subarachnoid Hemorrhage.

[Figure: see text].

Brain injury, endothelial injury and inflammatory markers are elevated and express sex-specific alterations after COVID-19.

OBJECTIVE: Although COVID-19 is a respiratory disease, all organs can be affected including the brain. To date, specific investigations of brain injury markers (BIM) and endothelial injury markers (EIM) have been limited. Additionally, a male bias in disease severity and mortality after COVID-19 is evident globally. Sex differences in the immune response to COVID-19 may mediate this disparity. We investigated BIM, EIM and inflammatory cytokine/chemokine (CC) levels after COVID-19 and in across sexes. METHODS: Plasma samples from 57 subjects at < 48 h of COVID-19 hospitalization, and 20 matched controls were interrogated for the levels of six BIMs-including GFAP, S100B, Syndecan-1, UCHLI, MAP2 and NSE, two EIMs-including sICAM1 and sVCAM1. Additionally, several cytokines/chemokines were analyzed by multiplex. Statistical and bioinformatics methods were used to measure differences in the marker profiles across (a) COVID-19 vs. controls and (b) men vs. women. RESULTS: Three BIMs: MAP2, NSE and S100B, two EIMs: sICAM1 and sVCAM1 and seven CCs: GRO IL10, sCD40L, IP10, IL1Ra, MCP1 and TNFα were significantly (p < 0.05) elevated in the COVID-19 cohort compared to controls. Bioinformatics analysis reveal a stronger positive association between BIM/CC/EIMs in the COVID-19 cohort. Analysis across sex revealed that several BIMs and CCs including NSE, IL10, IL15 and IL8 were significantly (p < 0.05) higher in men compared to women. Men also expressed a more robust BIM/ EIM/CC association profile compared to women. CONCLUSION: The acute elevation of BIMs, CCs, and EIMs and the robust associations among them at COVID-19 hospitalization are suggestive of brain and endothelial injury. Higher BIM and inflammatory markers in men additionally suggest that men are more susceptible to the risk compared to women.

Therapeutic Effects of Time-Limited Treatment with Brivaracetam on Posttraumatic Epilepsy after Fluid Percussion Injury in the Rat.

Mounting evidence suggests the synaptic vesicle glycoprotein 2A (SV2A) targeted by levetiracetam may contribute to epileptogenesis. Levetiracetam has shown anti-inflammatory, antioxidant, neuroprotective, and possible antiepileptogenic effects in brain injury and seizure/epilepsy models, and a phase 2 study has signaled a possible clinical antiepileptogenic effect. Brivaracetam shows greater affinity and specificity for SV2A than levetiracetam and broader preclinical antiseizure effects. Thus, we assessed the antiepileptogenic/disease-modifying potential of brivaracetam in an etiologically realistic rat posttraumatic epilepsy model optimized for efficient drug testing. Brivaracetam delivery protocols were designed to maintain clinical moderate-to-high plasma levels in young (5-week-old) male Sprague-Dawley rats for 4 weeks. Treatment protocols were rapidly screened in 4-week experiments using small groups of animals to ensure against rigorous testing of futile treatment protocols. The antiepileptogenic effects of brivaracetam treatment initiated 30 minutes, 4 hours, and 8 hours after rostral parasagittal fluid percussion injury (rpFPI) were then compared with vehicle-treated controls in a fully powered blind and randomized 16-week validation. Seizures were evaluated by video-electrocorticography using a 5-electrode epidural montage. Endpoint measures included incidence, frequency, duration, and spread of seizures. Group sizes and recording durations were supported by published power analyses. Three months after treatment ended, rats treated with brivaracetam starting at 4 hours post-FPI (the best-performing protocol) experienced a 38% decrease in overall incidence of seizures, 59% decrease in seizure frequency, 67% decrease in time spent seizing, and a 45% decrease in the proportion of spreading seizures that was independent of duration-based seizure definition. Thus, brivaracetam shows both antiepileptogenic and disease-modifying properties after rpFPI. SIGNIFICANCE STATEMENT: The rpFPI model, which likely incorporates epileptogenic mechanisms operating after human head injury, can be used to efficiently screen investigational treatment protocols and assess antiepileptogenic/disease-modifying effects. Our studies 1) support a role for SV2A in epileptogenesis, 2) suggest that brivaracetam and other drugs targeting SV2A should be considered for human clinical trials of prevention of post-traumatic epilepsy after head injury, and 3) provide data to inform the design of treatment protocols for clinical trials.

Cytokine-Laden Extracellular Vesicles Predict Patient Prognosis after Cerebrovascular Accident.

BACKGROUND: A major contributor to disability after hemorrhagic stroke is secondary brain damage induced by the inflammatory response. Following stroke, global increases in numerous cytokines-many associated with worse outcomes-occur within the brain, cerebrospinal fluid, and peripheral blood. Extracellular vesicles (EVs) may traffic inflammatory cytokines from damaged tissue within the brain, as well as peripheral sources, across the blood-brain barrier, and they may be a critical component of post-stroke neuroinflammatory signaling. METHODS: We performed a comprehensive analysis of cytokine concentrations bound to plasma EV surfaces and/or sequestered within the vesicles themselves. These concentrations were correlated to patient acute neurological condition by the Glasgow Coma Scale (GCS) and to chronic, long-term outcome via the Glasgow Outcome Scale-Extended (GOS-E). RESULTS: Pro-inflammatory cytokines detected from plasma EVs were correlated to worse outcomes in hemorrhagic stroke patients. Anti-inflammatory cytokines detected within EVs were still correlated to poor outcomes despite their putative neuroprotective properties. Inflammatory cytokines macrophage-derived chemokine (MDC/CCL2), colony stimulating factor 1 (CSF1), interleukin 7 (IL7), and monokine induced by gamma interferon (MIG/CXCL9) were significantly correlated to both negative GCS and GOS-E when bound to plasma EV membranes. CONCLUSIONS: These findings correlate plasma-derived EV cytokine content with detrimental outcomes after stroke, highlighting the potential for EVs to provide cytokines with a means of long-range delivery of inflammatory signals that perpetuate neuroinflammation after stroke, thus hindering recovery.

The contribution of postnatal steroid administration to early brain damage in preterm babies with bronchopulmonary dysplasia

Background/aim: Postnatal corticosteroids are commonly used to treat bronchopulmonary dysplasia (BPD). We aimed to show whether S100 calcium-binding B (S100B), neuron-specific enolase (NSE), Tau protein or microtubule-associated protein tau (MAPT), and glial fibrillary acid protein (GFAP) levels would provide any evidence of early neurological damage in premature infants receiving postnatal low dose dexamethasone therapy for BPD treatment. Materials and methods: In this cohort study, 136 preterm infants diagnosed with BPD at ≤32 weeks of gestation formed the study group, and 64 preterm infants formed the control group. NSE, S100B, GFAP, and MAPT levels were first measured before the postnatal corticosteroid treatment in both the patient and the control group on the 28th day and, for a second time, after treatment termination in the patient group. Results: There were significant differences between the measured GFAP, MAPT, and NSE values of the BPD and control groups on the 28th day, whereas there was no significant difference between the measured S100B values of the two groups. There were a statistically significant difference between the NSE values measured on the 28th day and after the treatment within the BPD group, whereas no significant difference existed between the GFAP, MAPT, and S100B values. Conclusion: NSE levels, which indicate brain damage in the early period, increased in preterm babies with BPD who had been administered postnatal dexamethasone.

Evaluation of neurofilament light chain in the cerebrospinal fluid and blood as a biomarker for neuronal damage in experimental pneumococcal meningitis.

BACKGROUND: Pneumococcal meningitis (PM) remains a global public health concern and affects all age groups. If acquired during infancy or childhood, permanent neurofunctional deficits including cognitive impairment, cerebral palsy, and secondary epilepsy are typical sequelae of neuronal injury. Determination of patients at risk for the development of brain injury and subsequent neurofunctional sequelae could help to identify patients for focused management. Neurofilament light chain (NfL) is an axonal cytoskeletal protein released upon neuronal injury into the cerebrospinal fluid (CSF) and blood. As little is known about the course of neurofilament release in the course of PM, we measured CSF and serum NfL levels longitudinally in experimental PM (ePM). METHODS: Eleven-day-old infant Wistar rats were infected intracisternally with Streptococcus pneumoniae and treated with ceftriaxone. At 18 and 42 h post-infection (hpi), the blood and CSF were sampled for NfL measurements by a single molecule array technology. Inflammatory cytokines and MMP-9 in CSF were quantified by magnetic bead multiplex assay (Luminex®) and by gel zymography, respectively. RESULTS: In ePM, CSF and serum NfL levels started to increase at 18 hpi and were 26- and 3.5-fold increased, respectively, compared to mock-infected animals at 42 hpi (p < 0.0001). CSF and serum NfL correlated at 18 hpi (p < 0.05, r = 0.4716) and 42 hpi (p < 0.0001, r = 0.8179). Both CSF and serum NfL at 42 hpi strongly correlated with CSF levels of IL-1ß, TNF-α, and IL-6 and of MMP-9 depending on their individual kinetics. CONCLUSION: Current results demonstrate that during the peak inflammatory phase of ePM, NfL levels in CSF and serum are the highest among CNS disease models studied so far. Given the strong correlation of CSF versus serum NfL, and its CNS-specific signal character, longitudinal measurements to monitor the course of PM could be performed based on blood sample tests, i.e., without the need of repetitive spinal taps. We conclude that NfL in the serum should be evaluated as a biomarker in PM.

Changes in Coagulation following Brain Injury.

Traumatic brain injury (TBI) is a worldwide public health concern due to increasing mortality, affecting around 10 million patients per year. A wide variety of clinical presentations are a function of the magnitude of injury and the anatomical perturbation of the brain parenchyma, supporting structures, and cerebral vasculature, with subsequent alteration of the blood-brain barrier. These disturbances correspond with the evolution of intracerebral hemorrhage and clinical outcomes. The associated hemostatic alterations associated with TBI are caused by the disruption of the delicate balance between bleeding and thrombosis formation, which can exacerbate initial injury. TBI-associated coagulopathy is a function of a cross-talk between coagulation and inflammation, with varying influences on the immunomodulation and regulation of coagulation that occur on platelets and the endothelium of injured TBI patients. In addition to the severity of initial injury, the following factors modulate the hemocoagulative response to TBI: time from the onset of injury to treatment, age, gender, catecholamine secretion, platelet dysfunction, endotheliopathy, premorbid anticoagulation, fibrinolysis, tissue factor, and activated protein C contribution. All these entities are intertwined and influence the pathologic evolution of TBI. These factors have implications for therapeutic options such as the choice of blood components for transfusion and hemostatic agents such as tranexamic acid. Monitoring hemostatic changes of TBI patients requires an understanding of these interactions between immunology and coagulation, which can be discerned by point-of-care viscoelastic testing with specific limitations. This review considers the implications of these interrelated influences on the evaluation of coagulopathy in TBI.

Mice with nucleus tractus solitarius injury induced by chronic restraint stress present impaired ability to raise blood glucose and glucagon levels when blood glucose levels plummet.

Chronic restraint stress (CRS) induces insulin-resistant hyperglycemia by inducing injury to the brain neurons in the nucleus tractus solitarius (NTS). However, the CRS mice did not suffer from hypoglycemia. In this study, mice of both CRS and NTS mechanical injury models were induced to investigate whether impaired glucose metabolism has changed upon the extension of the survival time after modeling. Body weight, food and water intake, fasting blood glucose, glucose tolerance, and glucose metabolism related to blood hormone levels were monitored for 12 weeks following the induction of injury. The mice were also administered with insulin intraperitoneally, and the blood glucose and glucagon levels were measured and compared to those in the control mice administered with saline. The results showed that the body weights of CRS-hyperglycemic mice were significantly higher than those in the control group, while the body weights of NTS mechanically injured mice were significantly lower than those in the control group. The food and water intake of both CRS-hyperglycemic and NTS mechanically injured mice were significantly more than those in the control groups. Although the levels of fasting blood glucose and resting serum hormone in the injured mice have returned to normal levels, the utilization of glucose and hypoglycemic counterregulation (the response that raises the blood glucose levels) was impaired in either CRS-hyperglycemic or NTS mechanically injured mice. The blood glucagon levels following insulin administration showed abnormal increase. These findings suggest that the CRS-induced NTS injury resulted not only in early insulin-resistant hyperglycemia but also impaired the ability to raise blood glucose and glucagon levels when blood glucose levels plummet in the later stage.

Post-operative acute kidney injury is associated with a biomarker of acute brain injury after paediatric cardiac surgery.

INTRODUCTION: Children with CHD who undergo cardiopulmonary bypass are at an increased risk of acute kidney injury. This study evaluated the association of end-organ specific injury plasma biomarkers for brain: glial fibrillary acidic protein and heart: Galectin 3, soluble suppression of tumorgenicity 2, and N-terminal pro b-type natriuretic peptide with acute kidney injury in children undergoing cardiopulmonary bypass. MATERIALS AND METHODS: We enrolled consecutive children undergoing cardiac surgery with cardiopulmonary bypass. Blood samples were collected pre-bypass in the operating room and in the immediate post-operative period. Acute kidney injury was defined as a rise of serum creatinine ≥50% from pre-operative baseline within 7 days after surgery. RESULTS: Overall, 162 children (mean age 4.05 years, sd 5.28 years) were enrolled. Post-operative acute kidney injury developed in 55 (34%) children. Post-operative plasma glial fibrillary acidic protein levels were significantly higher in patients with acute kidney injury (median 0.154 (inter-quartile range 0.059-0.31) ng/ml) compared to those without acute kidney injury (median 0.056 (inter-quartile range 0.001-0.125) ng/ml) (p = 0.043). After adjustment for age, weight, and The Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery category, each natural log increase in post-operative glial fibrillary acidic protein was significantly associated with a higher risk for subsequent acute kidney injury (adjusted odds ratio glial fibrillary acidic protein 1.25; 95% confidence interval 1.01-1.59). Pre/post-operative levels of galectin 3, soluble suppression of tumorgenicity 2, and N-terminal pro b-type natriuretic peptide did not significantly differ between patients with and without acute kidney injury. CONCLUSIONS: Higher plasma glial fibrillary acidic protein levels measured in the immediate post-operative period were independently associated with subsequent acute kidney injury in children after cardiopulmonary bypass. Elevated glial fibrillary acidic protein likely reflects intraoperative brain injury which may occur in the context of acute kidney injury-associated end-organ dysfunction.

Complement Inhibition Attenuates Early Erythrolysis in the Hematoma and Brain Injury in Aged Rats.

Background and Purpose- Early erythrolysis in the hematoma contributes to brain injury after intracerebral hemorrhage (ICH). This study investigated the effects of N-acetylheparin, a complement inhibitor, and aurin tricarboxylic acid, a membrane attack complex inhibitor, on early erythrolysis, brain iron deposition, and brain injury in aged rats. Methods- There were 3 parts in the study. First, aged (18 months old) male Fischer 344 rats had an ICH. The time course of erythrolysis in the hematoma was determined by T2* weighted magnetic resonance imaging, and the expression of CD163 was examined. Second, aged rats had an ICH with N-acetylheparin or vehicle. Rats were euthanized at days 1, 3, and 28 after magnetic resonance imaging (T2-, T2*-weighted, and T2* array) and behavioral tests. Brains were used for immunohistochemistry. Third, aged rats had an ICH with avaurin tricarboxylic acid or vehicle. The rats had magnetic resonance imaging and behavioral tests and were euthanized at day 3. Brains were used for immunohistochemistry. Results- Early erythrolysis occurred within the clot in aged F344 rats. There were increased numbers of CD163-positive cells after ICH. Almost all perihematomal CD163-positive cells were microglia/macrophages, while positive neurons were found more distant from the hematoma. Coinjection of N-acetylheparin attenuated erythrolysis, iron accumulation, CD163 expression, microglia activation, brain swelling, and neuronal death in the acute phase, as well as reducing brain atrophy and neurological deficits in the chronic phase. Coinjection of aurin tricarboxylic acid also reduced erythrolysis and ICH-induced brain injury. Conclusions- Inhibiting complement activation resulted in less erythrolysis and brain injury after ICH.

Plasma Levels, Temporal Trends and Clinical Associations between Biomarkers of Inflammation and Vascular Homeostasis after Pediatric Traumatic Brain Injury.

Expression of inflammatory (interleukin-6 [IL-6]) and vascular homeostatic (angiopoietin-2 [AP-2], endothelin-1 [ET-1], endocan-2 [EC-2]) biomarkers in pediatric traumatic brain injury (TBI) was examined in this prospective, observational cohort study of 28 children hospitalized with mild, moderate, and severe TBI by clinical measures (age, sex, Glasgow Coma Scale score [GCS], Injury Severity Score [ISS], and cerebral autoregulation status). Biomarker patterns suggest an inverse relationship between GCS and AP-2, GCS and IL-6, ISS and ET-1, but a direct relationship between GCS and ET-1 and ISS and AP-2. Biomarker patterns suggest an inverse relationship between AP-2 and ET-1, AP-2 and EC-2, but a direct relationship between AP-2 and IL-6, IL-6 and EC-2, and IL-6 and ET-1. Plasma concentrations of inflammatory and vascular homeostatic biomarkers suggest a role for inflammation and disruption of vascular homeostasis during the first 10 days across the severity spectrum of pediatric TBI. Although not statistically significant, without impact on cerebral autoregulation, biomarker patterns suggest a relationship between inflammation and alterations in vascular homeostasis. The large variation in biomarker levels within TBI severity and age groups, and by sex suggests other contributory factors to biomarker expression.

Compartmentalisation of the inflammatory response following aneurysmal subarachnoid haemorrhage.

INTRODUCTION: There is some evidence to suggest that a systemic and central nervous system (CNS) inflammatory response occurs following aneurysmal subarachnoid haemorrhage (aSAH) which may be related to the pathophysiology of early brain injury and delayed ischaemic neurological deficit (DIND). The aim of this study was to measure inflammatory mediator levels in plasma and cerebrospinal fluid (CSF) in the days following aSAH and to determine their association with aSAH, DIND and clinical outcome. MATERIAL AND METHODS: Plasma and CSF samples were obtained prospectively from patients with aSAH on days 1-3, 5, 7 and 9 and profiled for interleukin (IL)-1α, IL-1ß, IL-4, IL-6, IL-8, IL-10, IL-15, IL-17, IL-18, macrophage chemotactic protein (MCP)-1, vascular endothelial growth factor (VEGF) and tumour necrosis factor (TNF)-α. Plasma and CSF samples from non-aSAH patients undergoing spinal anaesthesia were used as controls. RESULTS: The CSF levels of all cytokines investigated except for IL-1α were significantly higher in aSAH compared to controls in the first seven days of ictus. CSF levels of IL-1α (p = 0.014), IL-18 (p = 0.016), IL-6 (p = 0.0006) and IL-8 (p = 0.006) showed significant increases in the days following aSAH. Conversely IL-17 demonstrated a decrease. In particular, IL-4 was higher in the CSF of patients who had DIND at all time-points (p = 0.032). Plasma IL-6 and IL-8 levels were higher, and IL-1α levels lower, than controls at most time-points. All mediators demonstrated persistent elevation in the CSF compared to plasma apart from IL-1α and IL-18 which followed the opposite trend. Day 3 plasma IL-6 levels predicted poor outcome at six months (Exp(B) 1.12 1.03-1.22, P = 0.012), although this association was lost in the second analysis incorporating Fisher grade, WFNS grade and age. CONCLUSION: The post aSAH inflammatory response peaks on days 5-7 post ictus and remains largely compartmentalised within the CNS. IL-4 may have a particular association with DIND although its precise role in the pathophysiology of the disorder remains unclear. IL-6 predicted poor outcome but not independently of clinical grade, suggesting that it may be a surrogate marker of early brain injury.

Dried blood spot compared to plasma measurements of blood-based biomarkers of brain injury in neonatal encephalopathy.

BACKGROUND: Data correlating dried blood spots (DBS) and plasma concentrations for neonatal biomarkers of brain injury are lacking. We hypothesized that candidate biomarker levels determined from DBS can serve as a reliable surrogate for plasma levels. METHODS: In the context of a phase II multi-center trial evaluating erythropoietin for neuroprotection in neonatal encephalopathy (NE), DBS were collected at enrollment ( < 24 h), day 2, 4, and 5. Plasma was collected with the first and last DBS. The relationship between paired DBS-plasma determinations of brain-specific proteins and cytokines was assessed by correlation and Bland-Altman analyses. For analytes with consistent DBS-plasma associations, DBS-derived biomarker levels were related to brain injury by MRI and 1-year outcomes. RESULTS: We enrolled 50 newborns with NE. While S100B protein, tumor necrosis factor α, interleukin (IL)1 ß, IL-6, IL-8 demonstrated significant DBS-plasma correlations, Bland-Altman plots demonstrated that the methods are not interchangeable, with a 2 to 4-fold error between measurements. No significant relationships were found between DBS levels of TNFα, IL-6, and IL-8 and outcomes. CONCLUSION: Further work is needed to optimize elution and assay methods before using DBS specimens as a reliable surrogate for plasma levels of candidate brain injury biomarkers in NE.

Post-mortem in situ stability of serum markers of cerebral damage and acute phase response.

The aim of the given study was to test the in situ stability of biochemical markers of cerebral damage and acute phase response in the early post-mortem interval to assess their usability for forensic pathology. A monocentric, prospective study investigated post-mortem femoral venous blood samples at four time points obtained within 48 h post-mortem starting at the death of 20 deceased, using commercial immunoassays for the ten parameters: S100 calcium-binding protein B (S100B), glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), brain-derived neurotrophic factor (BDNF), interleukin-6 (IL-6), C-reactive protein (CRP), procalcitonin (PCT), ferritin, soluble tumor necrosis factor receptor type 1 (sTNFR1), and lactate dehydrogenase (LDH). Significant changes in serum levels were observed only later than 2 h after death for all markers. Inter-laboratory comparability was high, and intra-assay precision was sufficient for most markers. Most of the biomarker levels depended on the severity of hemolysis and lipemia but were robust against freeze-thaw cycles. Serum levels increased with longer post-mortem intervals for S100B, NSE, ferritin, sTNFR1, and LDH (for all p < 0.001) but decreased over this period for CRP (p = 0.089) and PCT (p < 0.001). Largely unchanged median values were found for GFAP (p = 0.139), BDNF (p = 0.106), and IL-6 (p = 0.094). Serum levels of CRP (p = 0.059) and LDH (p = 0.109) did not differ significantly between the final ante-mortem (resuscitation) and the first post-mortem sample (moment of death). Collecting the post-mortem blood sample as soon as possible will reduce the influence of post-mortem blood changes. Serum GFAP for detection of cerebral damage as well as serum IL-6 and CRP as proof of acute phase response seemed to be preferable due to their in situ stability in the first 2 days after death.