Severity Of Ischemic Brain Injury Research Articles

A Case of Multidrug-Resistant Lance-Adams Syndrome Successfully Treated With Phenobarbital.

Lance-Adams syndrome is a rare but devastating disorder characterized by rest, action, and stimulus-sensitive myoclonus after cardiorespiratory arrest. We aimed to present a case of multidrug-resistant Lance-Adams syndrome that was successfully treated with oral phenobarbital therapy. We report a previously healthy 11-year, 6-month-old boy was referred to our pediatric intensive care unit because of severe hypoxic ischemic brain injury due to sudden cardiorespiratory arrest. On the 15th day of hospitalization, he developed myoclonic jerks involving his limbs, trunk, and eyes. Despite many antiseizure medications in different combinations, myoclonic jerks persisted. Then, phenobarbital was started, and myoclonic jerks disappeared the next day. At the final evaluation, additional phenobarbital treatment was continued for 6 months and the patient remained myoclonus-free during this time. To the best of our knowledge, this case is the first report describing significant improvement with phenobarbital in a patient with multidrug-resistant Lance-Adams syndrome. We suggest that phenobarbital is an effective option and should be kept in mind in patients with multidrug-resistant Lance-Adams syndrome.

Astaxanthin Confers a Significant Attenuation of Hippocampal Neuronal Loss Induced by Severe Ischemia-Reperfusion Injury in Gerbils by Reducing Oxidative Stress.

Astaxanthin is a powerful biological antioxidant and is naturally generated in a great variety of living organisms. Some studies have demonstrated the neuroprotective effects of ATX against ischemic brain injury in experimental animals. However, it is still unknown whether astaxanthin displays neuroprotective effects against severe ischemic brain injury induced by longer (severe) transient ischemia in the forebrain. The purpose of this study was to evaluate the neuroprotective effects of astaxanthin and its antioxidant activity in the hippocampus of gerbils subjected to 15-min transient forebrain ischemia, which led to the massive loss (death) of pyramidal cells located in hippocampal cornu Ammonis 1-3 (CA1-3) subfields. Astaxanthin (100 mg/kg) was administered once daily for three days before the induction of transient ischemia. Treatment with astaxanthin significantly attenuated the ischemia-induced loss of pyramidal cells in CA1-3. In addition, treatment with astaxanthin significantly reduced ischemia-induced oxidative DNA damage and lipid peroxidation in CA1-3 pyramidal cells. Moreover, the expression of the antioxidant enzymes superoxide dismutase (SOD1 and SOD2) in CA1-3 pyramidal cells were gradually and significantly reduced after ischemia. However, in astaxanthin-treated gerbils, the expression of SOD1 and SOD2 was significantly high compared to in-vehicle-treated gerbils before and after ischemia induction. Collectively, these findings indicate that pretreatment with astaxanthin could attenuate severe ischemic brain injury induced by 15-min transient forebrain ischemia, which may be closely associated with the decrease in oxidative stress due to astaxanthin pretreatment.

Abstract TP242: The Suppression Of Leukocyte Rolling Via Blocking P-selectin After Stroke Is Not Sustained In Mice With Type 2 Diabetes

Introduction: Diabetes is associated with worse stroke outcome, yet the mechanism contributing to a more severe ischemic brain injury is not well understood. Neutrophils invade the cerebral veins as early as 30 minutes after stroke and play a major role in acute ischemic brain injury and thrombosis. Leukocyte rolling on the activated endothelium is an early event of transendothelial migration and parenchymal infiltration of leukocytes including neutrophils, which involves p-selectin. The current study sought to determine the effect of blocking p-selectin in reducing leukocyte rolling in the cerebral vessels of diabetic mice after stroke. Methods: Stroke was induced in 4-month old diabetic db/db and control db/+ mice via middle cerebral artery occlusion (MCAO). P-selectin blocking antibody (P-aby) was administered intravenously 30 min after MCAO at 20 mg/kg. Adherent or rolling leukocytes was quantified at baseline before MCAO and after ischemic reperfusion by repeated 2-photon microscope imaging with fluorescent tracers. Infiltrating neutrophils and plasma soluble p-selectin were determined via FACS and ELISA, respectively. Results: Leukocyte rolling was immediate detected in the veins 1 hr after reperfusion and significantly increased 1d after MCAO in both genotypes of mice. Rolling tended to last days longer in the db/db compared to db/+ mice, and was often seen in the arterioles of the former but not in the latter mice. Increased infiltration of neutrophils was detected in db/db compared to db/+ brain parenchyma 1-3 ds after MCAO by FACS. Three to 5 fold-reduction in rolling by was detected 1 hr after reperfusion in both genotypes following P-aby treatment. However, rolling resumed in db/db mice 1 d after MCAO and antibody treatment, compared to a sustained suppression of rolling seen in the db/+ mice till days later. Elevated soluble p-selectin was also detected in the plasma of db/db compared to db/+ mice. Conclusions: Stroke-induced leukocyte rolling was only temporarily suppressed by P-selectin blocking antibody in db/db mice. Ongoing studies will determine the effect of P-selectin blocking on microthrombi formation, cerebral blood flow, neuroprotection and the role of soluble p-selectin in dampening the treatment effect.

BDNF-Overexpressing Engineered Mesenchymal Stem Cells Enhances Their Therapeutic Efficacy against Severe Neonatal Hypoxic Ischemic Brain Injury.

We investigated whether irradiated brain-derived neurotropic factor (BDNF)-overexpressing engineered human mesenchymal stem cells (BDNF-eMSCs) improve paracrine efficiency and, thus, the beneficial potency of naïve MSCs against severe hypoxic ischemic (HI) brain injury in newborn rats. Irradiated BDNF-eMSCs hyper-secreted BDNF > 10 fold and were >5 fold more effective than naïve MSCs in attenuating the oxygen-glucose deprivation-induced increase in cytotoxicity, oxidative stress, and cell death in vitro. Only the irradiated BDNF-eMSCs, but not naïve MSCs, showed significant attenuating effects on severe neonatal HI-induced short-term brain injury scores, long-term progress of brain infarct, increased apoptotic cell death, astrogliosis and inflammatory responses, and impaired negative geotaxis and rotarod tests in vivo. Our data, showing better paracrine potency and the resultant better therapeutic efficacy of the irradiated BDNF-eMSCs, compared to naïve MSCs, suggest that MSCs transfected with the BDNF gene might represent a better, new therapeutic strategy against severe neonatal HI brain injury.

Neurological outcome in patients after successful resuscitation in out-of-hospital settings.

Neurological outcome is an important determinant of death in admitted survivors after out-of-hospital cardiac arrest (OHCA). Studies demonstrated several significant pre-hospital predictors of ischemic brain injury (time to resuscitation, time of resuscitation, and cause of OHCA). Our aim was to evaluate the relationship between post-resuscitation clinical parameters and neurological outcome in OHCA patients, when all recommended therapeutic strategies, including hypothermia, were on board. We retrospectively included consecutive 110 patients, admitted to the medical ICU after successful resuscitation due to OHCA. Neurological outcome was defined by cerebral performance category (CPC) scale I-V. CPC categories I-II defined good neurological outcome and CPC categories III-V severe ischemic brain injury. Therapeutic measures were aimed to achieve optimal circulation and oxygenation, early percutaneous coronary interventions (PCI) in acute coronary syndromes (ACS), and therapeutic hypothermia to improve survival and neurological outcome of OHCA patients. We observed good neurological outcome in 37.2% and severe ischemic brain injury in 62.7% of patients. Severe ischemic brain injury was associated significantly with known pre-hospital data (older age, cause of OHCA, and longer resuscitations), but also with increased admission lactate, in-hospital complications (involuntary muscular contractions/seizures, heart failure, cardiogenic shock, acute kidney injury, and mortality), and inotropic and vasopressor support. Good neurological outcome was associated with early PCI, dual antiplatelet therapy, and better survival. We conclude that in OHCA patients, post-resuscitation early PCI and dual antiplatelet therapy in ACS were significantly associated with good neurological outcome, but severe ischemic brain injury was associated with several in-hospital complications and the need for vasopressor and inotropic support.

Poly-Arginine Peptide-18 (R18) Reduces Brain Injury and Improves Functional Outcomes in a Nonhuman Primate Stroke Model.

Poly-arginine peptide-18 (R18) is neuroprotective in different rodent middle cerebral artery occlusion (MCAO) stroke models. In this study, we examined whether R18 treatment could reduce ischemic brain injury and improve functional outcome in a nonhuman primate (NHP) stroke model. A stroke was induced in male cynomolgus macaques by MCAO distal to the orbitofrontal branch of the MCA through a right pterional craniotomy, using a 5-mm titanium aneurysm clip for 90min. R18 (1000nmol/kg) or saline vehicle was administered intravenously 60min after the onset of MCAO. Magnetic resonance imaging (MRI; perfusion-weighted imaging, diffusion-weighted imaging, or T2-weighted imaging) of the brain was performed 15min, 24h, and 28days post-MCAO, and neurological outcome was assessed using the NHP stroke scale (NHPSS). Experimental endpoint was 28days post-MCAO, treatments were randomized, and all procedures were performed blinded to treatment status. R18 treatment reduced infarct lesion volume by up to 65.2% and 69.7% at 24h and 28days poststroke, respectively. Based on NHPSS scores, R18-treated animals displayed reduced functional deficits. This study confirms the effectiveness of R18 in reducing the severity of ischemic brain injury and improving functional outcomes after stroke in a NHP model, and provides further support for its clinical development as a stroke neuroprotective therapeutic.

Chronic high-fat diet-induced obesity in gerbils increases pro-inflammatory cytokines and mTOR activation, and elicits neuronal death in the striatum following brief transient ischemia

Recent studies have shown that obesity and its related metabolic dysfunction exacerbate outcomes of ischemic brain injuries in some brain areas, such as the hippocampus and cerebral cortex when they are subjected to transient ischemia. However, the impact of obesity in the striatum after brief transient ischemia has not yet been addressed. The objective of this study was to investigate effects of obesity on neuronal damage and inflammation in the striatum after transient ischemia and to examine the role of mTOR which is involved in the pathogenesis of metabolic and neurological diseases. Gerbils were fed with normal diet (ND) or high-fat diet (HFD) for 12 weeks and subjected to 5 min of transient ischemia. HFD-fed gerbils showed significant increase in body weight, blood glucose level, serum triglycerides, total cholesterol and low-density lipoprotein cholesterol without affecting food intake. Neuronal death/loss in the HFD-fed gerbils occurred in the dorsolateral striatum 2 days after transient ischemia, and neuronal loss was increased 5 days after transient ischemia, although no neuronal loss was observed in ND-fed gerbils at any time after transient ischemia. The HFD-fed gerbils showed hypertrophied microglia and further increased expressions of tumor necrosis factor-alpha, interukin-1beta, mammalian target of rapamycin (mTOR) and phosphorylated-mTOR during pre- and post-ischemic phases compared with the ND-fed gerbils. Additionally, we found that treatment with mTOR inhibitor rapamycin in the HFD-fed gerbils significantly attenuated transient ischemia-induced neuronal death in the dorsolateral striatum. These findings reveal that chronic HFD-induced obesity results in severe neuroinflammation and significant increase of mTOR activation, which could contribute to neuronal death in the stratum following 5 min of transient ischemia. Especially, abnormal mTOR activation would play a key role in mediating obesity-induced severe ischemic brain injury.

Curative effects of GM1 in the treatment of severe ischemic brain injury and its effects on serum TNF-α and NDS.

The curative effects of monosialotetrahexosyl ganglioside (GM1) in the treatment of severe ischemic brain injury and its effects on tumor necrosis factor-α (TNF-α) and neuropathy disability score (NDS). Sixty patients with severe ischemic brain injury admitted to The First People's Hospital of Jining (Jining, China) from June 2014 to March 2016 were selected. They were randomly divided into the control group (n=30) and the experimental group (n=30). The patients in the control group were treated with routine therapy while those in the experimental group were treated with GM1. The level of TNF-α in the serum was measured by the enzyme-linked immunosorbent assay. The NDS was used to grade the two groups; Pearson's correlation coefficient was applied to analyze the correlation between the content of TNF-α and NDS; the content of superoxide dismutase (SOD) was detected using xanthine oxidase assay, and the content of malondialdehyde (MDA) was detected by thiobarbituric acid method. The clinical recovery time of two groups of patients was recorded. At 14 days after GM1 treatment, the serum TNF-α content and the NDS in the experimental group were significantly lower than those in the control group (P<0.05). The content of TNF-α in the patients was positively correlated with the NDS. After treatment, the serum MDA content of patients in the experimental group was lower, while the SOD content was significantly higher than that in the control group (P<0.05). After GM1 treatment, hemodynamic parameters of patients in the experimental group were significantly improved compared with those in the control group. The total effective rate of GM1 treatment in the experimental group was higher than that in the control group (P<0.05). GM1 has a good clinical significance in the treatment of patients with severe ischemic brain injury and is worthy of clinical promotion and application.

GW28-e0087 Astrocytic Endothelin-1 Overexpression Regulates Neurogenesis after Stroke in Mice

Endothelin-1 (ET-1) is up-regulated in astrocytes under ischemia. Our previous studies suggest that astrocytic ET-1 has deleterious effects on water homeostasis, cerebral edema and BBB integrity, which contribute to more severe ischemic brain injury. We also found that astrocytic ET-1 plays a

Microdialysis combined with UPLC–MS/MS method for determination of tetramethylpyrazine and ferulic acid in striatum of awake and anesthetic rats subjected to cerebral ischemia

A rapid, sensitive and selective ultra-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) method has been developed for the simultaneous determination and pharmacokinetic investigation of Tetramethylpyrazine (TMP) and Ferulic acid (FA) in rat striatum. The method was validated over the concentration range of 1.15–505ng/mL for TMP and 3.23–101ng/mL for FA, with a lower limit of quantitation (LLOQ) of 1.15ng/mL and 3.23ng/mL, respectively. This method can be successfully applied in pharmacokinetic studies of TMP and FA in striatum of awake and anesthetic rats. The cerebral blood flow velocity (CBF) during middle cerebral artery occlusion (MCAO) was monitored by Laser speckle contrast imaging, to observe whether the compatibility of TMP and FA could improve CBF against cerebral ischemia/reperfusion (I/R) injury. Infarct volume was examined to evaluate severity of ischemic brain injury. The pharmacokinetic study indicated that T1/2, Cmax, MRT and AUC0-inf were changed after combined administration of TMP and FA, when compared with either drug alone both in awake and anesthetic groups. The pharmacodynamics results showed that co-administration of drugs could enhance the CBF during middle cerebral artery occlusion and reduced the infarct volume. Taken together, the compatibility treatment of TMP and FA might be a promising therapeutic strategy for ischemic stroke. Further study is required to optimize the compatibility proportion.

Results of Extracorporeal Cardiopulmonary Resuscitation in Children.

BackgroundSurvival of children experiencing cardiac arrest refractory to conventional cardiopulmonary resuscitation (CPR) is very poor. We sought to examine current era outcomes of extracorporeal CPR (ECPR) support for refractory arrest.MethodsPatients who were <18 years and underwent ECPR between November 2013 and January 2016 were including in this study. We retrospectively investigated patient medical records.ResultsTwelve children, median age 6.6 months (range, 1 day to 11.7 years), required ECPR. patients’ diseases spanned several categories: congenital heart disease (n=5), myocarditis (n=2), respiratory failure (n=2), septic shock (n=1), trauma (n=1), and post-cardiotomy arrest (n=1). Cannulation sites included the neck (n=8), chest (n=3), and neck to chest conversion (n=1). Median duration of extracorporeal membrane oxygenation was five days (range, 0 to 14 days). Extracorporeal membrane oxygenation was successfully discontinued in 10 (83.3%) patients. Nine patients (75%) survived more than seven days after support discontinuation and four patients (33.3%) survived and were discharged. Causes of death included ischemic brain injury (n=4), sepsis (n=3), and gastrointestinal bleeding (n=1).ConclusionECPR plays a valuable role in children experiencing refractory cardiac arrest. The weaning rate is acceptable; however, survival is related to other organ dysfunction and the severity of ischemic brain injury. ECPR prior to the emergence of end-organ injury and prevention of neurologic injury might enhance survival.

Hypoxic–Ischemic brain injury in an adult: Magnetic Resonance Imaging findings

Hypoxic–ischemic brain injury (HIBI) is not uncommon in day to day clinical practice. It occurs in cases of cardiac arrest that are revived by cardiac resuscitation. Though the diagnosis of HIBI in these patients is never in doubt due to the sequence of events, however imaging is done to assess the amount of damage and to prognosticate the outcome. We present here magnetic resonance imaging (MRI) findings in a case of severe hypoxic ischemic brain injury.

White cerebellum sign: red flag in the emergency department

A 3-year-old boy presented to the emergency department with fever, generalized tonic-clonic seizures, and altered sensorium within 6 hours of administration of the diphtheria, pertussis, and tetanus (DPT) vaccine. The child had features suggestive of raised intracranial pressure with papilledema on fundoscopic examination. Contrast-enhanced computed tomography (CT) of the head (Figure 1) revealed diffuse hypodense attenuation of bilateral cerebral hemispheres with effacement of the basal cisterns and sulcal spaces. The cerebellum showed normal attenuation, thus appearing hyperdense relative to the cerebral parenchyma. This is known as the white cerebellum sign. Despite the best possible efforts, the patient passed away. The white cerebellum sign is a pointer toward severe hypoxic ischemic brain injury. It has been described in conditions such as birth asphyxia, head injury, drowning, status epilepticus, hypothermia, meningoencephalitis, and other causes of global hypoperfusion. The white cerebellum sign results from diffuse cerebral edema leading to loss of normal grey-white matter differentiation of the cerebral parenchyma. It is postulated that there is preferential blood flow to the posterior fossa structures in severe anoxia, thereby preserving the normal appearance of the cerebellum, making it look brighter on CT evaluation. The white cerebellum sign suggests a poor prognosis indicative of irreversible brain damage. Knowledge of this sign is important from a diagnostic, therapeutic, and prognostic standpoint.

Surgery-Related Thrombosis Critically Affects the Brain Infarct Volume in Mice Following Transient Middle Cerebral Artery Occlusion

Transient middle cerebral artery occlusion (tMCAO) model is widely used to mimic human focal ischemic stroke in order to study ischemia/reperfusion brain injury in rodents. In tMCAO model, intraluminal suture technique is widely used to achieve ischemia and reperfusion. However, variation of infarct volume in this model often requires large sample size, which hinders the progress of preclinical research. Our previous study demonstrated that infarct volume was related to the success of reperfusion although the reason remained unclear. The aim of present study is to explore the relationship between focal thrombus formation and model reproducibility with respect to infarct volume. We hypothesize that suture-induced thrombosis causes infarct volume variability due to insufficient reperfusion after suture withdrawal. Seventy-two adult male CD-1 mice underwent 90 minutes of tMCAO with or without intraperitoneal administration of heparin. Dynamic synchrotron radiation microangiography (SRA) and laser speckle contrast imaging (LSCI) were performed before and after tMCAO to observe the cerebral vascular morphology and to measure the cerebral blood flow in vivo. Infarct volume and neurological score were examined to evaluate severity of ischemic brain injury. We found that the rate of successful reperfusion was much higher in heparin-treated mice compared to that in heparin-free mice according to the result of SRA and LSCI at 1 and 3 hours after suture withdrawal (p<0.05). Pathological features and SRA revealed that thrombus formed in the internal carotid artery, middle cerebral artery or anterior cerebral artery, which blocked reperfusion following tMCAO. LSCI showed that cortical collateral circulation could be disturbed by thrombi. Our results demonstrated that suture-induced thrombosis was a critical element, which affects the success of reperfusion. Appropriate heparin management provides a useful approach for improving reproducibility of reperfusion model in mice.

Polymorphisms in migraine-associated gene, atp1a2, and ischemic stroke risk in a biracial population: the genetics of early onset stroke study

In a recent meta-analysis migraine was associated with a two-fold increase in stroke risk. While the mechanism driving this association is unknown, one intriguing hypothesis is that migraineurs are genetically predisposed to developing ischemic stroke. Mutations in the ATP1A2 gene are implicated in familial hemiplegic migraine type II and increase the severity of ischemic brain injury in animal models. To further explore these observations, we assessed the association between ATP1A2 polymorphisms, migraine, and the risk of ischemic stroke in participants of the Genetics of Early-Onset Stroke Study, a population-based case–control study of ischemic stroke among men and women aged 15–49. Using responses to a headache symptoms questionnaire, subjects were classified as having no migraine, or migraine with or without visual aura. Evaluating a total of 134 ATP1A2 polymorphisms genotyped using a combination of Illumina platforms (Cardiovascular Gene-centric 50 K SNP Array and HumanOmni1-Quad_v1-0_B Bead Chip), only one polymorphism (rs2070704) demonstrated a nominally significant association with stroke in an age-, gender-, ethnicity-adjusted model (OR = 0.83, 95% CI = 0.71-0.98, p = 0.025) and in a vascular risk factor model adjusting for age, gender, ethnicity, hypertension, diabetes, smoking, and myocardial infarction (OR = 0.74, 95% CI = 0.63-0.89, p = 0.001). Ethnicity-stratified analyses demonstrated a significant association for rs2070704 among African-Americans (OR = 0.68, 95% CI = 0.53-0.90, p = 0.005) but not Caucasians (OR = 0.82, 95% CI = 0.64-1.04, p = 0.107). These associations were unchanged when migraine subtypes were included as co-variates. We did not observe an association between ATP1A2 polymorphisms and migraine. While our results do not demonstrate a strong relationship between ATP1A2 polymorphisms and migraine associated stroke risk, the results are hypothesis generating and indicate that an association between ATP1A2 polymorphisms and stroke risk may exist. Additional studies are required.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-2-46) contains supplementary material, which is available to authorized users.

Application of Electrophysiologic Techniques in Poor Outcome Prediction Among Patients With Severe Focal and Diffuse Ischemic Brain Injury

To explore various electrophysiologic examinations as predictors for poor outcome in patients with severe ischemic brain injury, by comparing the prognostic ability of EEG, short-latency somatosensory evoked potentials (SLSEP), and brain stem auditory evoked potentials (BAEP). EEG, SLSEP, and BAEP were recorded in 161 patients with severe ischemic brain injuries (Glasgow Coma Scale ≤ 8), 77 with anoxic-ischemic encephalopathy after cardiopulmonary resuscitation, while 84 experienced massive hemispheric infarction at between 1 and 7 days after the onset. Outcomes were reviewed after 6 months using the Glasgow Outcome Scale. Six months after the onset, poor outcomes (Glasgow Outcome Scale, 1-2) were identified in 66 and 54 patients among the anoxic-ischemic encephalopathy and the massive hemispheric infarction group, respectively. By using the prognostic authenticity analysis of predictors, unfavorable EEG patterns, lack of EEG reactivity, pathologic N20 of SLSEP, and pathologic wave V of BAEP showed the high sensitivity (92.4%-97.0%, 95% confidence interval [CI]: 82.5%-99.5%), while bilateral absence of SLSEP N20 showed the highest specificity (100%, 95% CI: 67.9%-100%) and positive predictive value (100%, 95% CI: 90.4%-100%) in the anoxic-ischemic encephalopathy group. In the massive hemispheric infarction group, unfavorable EEG patterns showed the highest sensitivity (96.3%, 95% CI: 86.2%-99.4%) while bilateral absence of SLSEP N20 and BAEP wave V showed the highest specificity (100%, 95% CI: 85.9%-100%) and positive predictive value (100%, 95% CI: 80.8%-100%). The predictive power of electrophysiologic examinations is different according to the etiology of ischemic brain injury. Short-latency somatosensory evoked potentials (N20) can be considered the most powerful method to predict poor outcome in anoxic-ischemic encephalopathy. Combination of EEG (unfavorable EEG patterns) and SLSEP (N20)/BAEP (wave V) is best suited in massive hemispheric infarction to predict poor outcome.

Cutting-edge Discussions of Management, Policy, and Program Issues in Emergency Care

Cutting-edge Discussions of Management, Policy, and Program Issues in Emergency Care

High Serum Levels of Endothelin-1 Predict Severe Cerebral Edema in Patients With Acute Ischemic Stroke Treated With t-PA

Severe cerebral edema is associated with poor outcome in patients with acute stroke. Experimental studies suggest that astrocytic endothelin-1 (ET-1) has deleterious effects on water homeostasis, cerebral edema, and blood brain barrier (BBB) integrity, which contribute to more severe ischemic brain injury. In this study we analyze the association between high serum levels of ET-1 and the development of severe cerebral edema in patients treated with t-PA. One hundred thirty-four patients treated with t-PA according SITS-MOST (Safe Implementation of Thrombolysis in Stroke Monitoring Study) criteria were prospectively studied. Serum levels of ET-1, matrix metalloproteinase-9 (MMP-9), and cellular fibronectin (c-Fn) were determined by ELISA in serum samples obtained on admission, before t-PA bolus. Severe brain edema was diagnosed if extensive swelling caused any shifting of the structures of the midline was detected on the cranial CT performed at 24 to 36 hours. Stroke severity was evaluated before t-PA administration and at 24 hours by NIHSS. Functional outcome at 3 months was evaluated by the modified Rankin Scale (mRS). Nineteen patients (14.2%) developed severe brain edema. Median ET-1 (8.4 [6.7, 9.6] versus 1.9 [1.6, 3.2] fmol/mL, P<0.0001) and c-Fn (6.0 [4.1, 6.7] versus 3.2 [2.1, 4.6] mg/L, P<0.0001) serum levels were significantly higher in patients with severe cerebral edema. The best cut-off values for ET-1 and c-Fn serum levels for the prediction of severe brain edema were 5.5 fmol/mL (sensitivity 95% and specificity 94%) and 4.5 mg/L (sensitivity 73% and specificity 77%) respectively. ET-1 serum levels >5.5 fmol/mL before t-PA treatment were independently associated with development of severe brain edema (OR, 139.7; CI95%, 19.3 to 1012.2; P<0.0001), after adjustment for baseline stroke severity, early CT signs of infarction, serum levels of cFn >4.5 mg/L, and cardioembolic stroke subtype. ET-1 serum levels >5.5 fmol/mL are associated with severe brain edema in acute stroke patients treated with t-PA. These results suggest that ET-1 may be a new diagnostic marker for development of severe brain edema in patients with acute ischemic stroke treated with t-PA.

Serum insulin-like growth factor I and ischemic brain injury

Serum insulin-like growth factor I (IGF-I), which is mostly produced by the liver, has recently been shown to have the unexpected ability to modulate normal brain function as well as brain response to injury. Moreover, serum IGF-I levels are modified in many brain diseases, including stroke. However, whether these modifications are related to the disease process remains uncertain. We now examined a potential relationship between serum IGF-I and ischemic brain injury after middle cerebral artery occlusion (MCAo) and reperfusion in mice with either high or low serum IGF-I levels prior to insult. Surprisingly, we found that chronic high serum IGF-I correlates with increased brain infarct size following MCAo, while low levels correlate with reduced lesion size. Immunocytochemistry and immunoblot analyses revealed that levels of phosphorylated (i.e., activated) MAPK, known to be associated with the severity of ischemic brain injury, were increased in IGF-I treated mice. No overall effect of IGF-I treatment on IGF family mRNA expression in the brain was observed. Altogether, these results indicate that serum IGF-I levels negatively correlate with stroke outcome. Therefore, lowering serum IGF-I levels in aging mammals, including humans, may be beneficial against the increased risk of stroke associated to old age.

Endothelin-1 Overexpression Leads to Further Water Accumulation and Brain Edema after Middle Cerebral Artery Occlusion via Aquaporin 4 Expression in Astrocytic End-Feet

Stroke patients have increased levels of endothelin-1 (ET-1), a strong vasoconstrictor, in their plasma or cerebrospinal fluid. Previously, we showed high level of ET-1 mRNA expression in astrocytes after hypoxia/ischemia. It is unclear whether the contribution of ET-1 induction in astrocytes is protective or destructive in cerebral ischemia. Here, we generated a transgenic mouse model that overexpress ET-1 in astrocytes (GET-1) using the glial fibrillary acidic protein promoter to examine the role of astrocytic ET-1 in ischemic stroke by challenging these mice with transient middle cerebral artery occlusion (MCAO). Under normal condition, GET-1 mice showed no abnormality in brain morphology, cerebrovasculature, absolute cerebral blood flow, blood-brain barrier (BBB) integrity, and mean arterial blood pressure. Yet, GET-1 mice subjected to transient MCAO showed more severe neurologic deficits and increased infarct, which were partially normalized by administration of ABT-627 (ET(A) antagonist) 5 mins after MCAO. In addition, GET-1 brains exhibited more Evans blue extravasation and showed decreased endothelial occludin expression after MCAO, correlating with higher brain water content and increased cerebral edema. Aquaporin 4 expression was also more pronounced in astrocytic end-feet on blood vessels in GET-1 ipsilateral brains. Our current data suggest that astrocytic ET-1 has deleterious effects on water homeostasis, cerebral edema and BBB integrity, which contribute to more severe ischemic brain injury.