Extracellular glutamate and other amino acids in experimental intracerebral hemorrhage: an in vivo microdialysis study

Ischemic Stroke: Pathophysiology and Evolving Treatment Approaches

Stroke remains a leading cause of mortality and disability, with ischemic stroke being the most common type. It occurs due to reduced cerebral blood flow, leading to a cascade of events initiated by oxygen and nutrient deprivation, triggering excitotoxicity, oxidative stress, and inflammation and finally culminating in neuronal injury and death. Key molecular players in ischemic stroke include glutamate receptors, acid-sensing ion channels, and purinergic receptors, exacerbating cellular damage through calcium influx, oxidative stress, and mitochondrial dysfunction. Understanding these mechanisms has shaped therapeutic strategies, such as neuroprotective agents and stem cell therapies. Current treatments such as tissue plasminogen activator (tPA) emphasize timely intervention, yet challenges persist in patient-specific variability and accessibility. This review provides an overview of ischemic stroke pathophysiology, emphasizing cellular responses to ischemia and current and future therapeutic approaches including stem cell therapies aimed at mitigating stroke-induced disabilities and improving long-term outcomes.

Exploring Metabolic Aberrations after Intracerebral Hemorrhage In Vivo with Deuterium Metabolic Spectroscopy Imaging

Aberrations in metabolism after intracerebral hemorrhage (ICH), particularly lactate metabolism, play a crucial role in the pathophysiology and patient outcome. To date, the evaluation of metabolism relies heavily on invasive methods such as microdialysis, restricting a comprehensive understanding of the metabolic mechanisms associated with ICH. This study proposes a noninvasive metabolic imaging method based on 2H magnetic resonance spectroscopy and imaging (2H-MRS/MRSI) to detect metabolic changes after ICH in vivo. To overcome the low-sensitivity limitation of 2H, we designed a new 1H-2H double-resonance coil with 2H-channel active detuning and proposed chemical shift imaging based on the balanced steady-state free precession method (CSI-bSSFP). Compared with the volume coil, the signal-to-noise ratio (SNR) of the new coil was increased by 4.5 times. In addition, the SNR of CSI-bSSFP was 1.5 times higher than that of conventional CSI. These two technologies were applied to measure lactate metabolic flux at different phases of ICH. The results show a higher lactate concentration in ICH rats than in control rats, which is in line with the increased expression of lactate dehydrogenase measured via immunohistochemistry staining (AUCLac_area/Glc_area: control, 0.08 ± 0.02 vs ICH-3d, 0.39 ± 0.05 vs ICH-7d, 0.18 ± 0.02, P < 0.01; H-score: control, 126.4 ± 5.03 vs ICH-3d, 168.4 ± 5.71 vs ICH-7d,133.6 ± 7.70, P < 0.05). A higher lactate signal also appeared near the ICH region than in normal brain tissue. In conclusion, 2H-MRS/MRSI shows potential as a useful method for in vivo metabolic imaging and noninvasive assessment of ICH.

Beyond boundaries: The therapeutic potential of exosomes in neural microenvironments in neurological disorders

Neurological disorders are a diverse group of conditions that can significantly impact individuals' quality of life. The maintenance of neural microenvironment homeostasis is essential for optimal physiological cellular processes. Perturbations in this delicate balance underlie various pathological manifestations observed across various neurological disorders. Current treatments for neurological disorders face substantial challenges, primarily due to the formidable blood-brain barrier and the intricate nature of neural tissue structures. These obstacles have resulted in a paucity of effective therapies and inefficiencies in patient care. Exosomes, nanoscale vesicles that contain a complex repertoire of biomolecules, are identifiable in various bodily fluids. They hold substantial promise in numerous therapeutic interventions due to their unique attributes, including targeted drug delivery mechanisms and the ability to cross the BBB, thereby enhancing their therapeutic potential. In this review, we investigate the therapeutic potential of exosomes across a range of neurological disorders, including neurodegenerative disorders, traumatic brain injury, peripheral nerve injury, brain tumors, and stroke. Through both in vitro and in vivo studies, our findings underscore the beneficial influence of exosomes in enhancing the neural microenvironment following neurological diseases, offering promise for improved neural recovery and management in these conditions.

miRNAs as modulators of neuroinflammation and excitotoxicity: Implications for stroke therapeutics

Stroke is a widespread neurological disorder associated with physical disabilities, mortality, and economic burden. In recent decades, substantial progress has been achieved in reducing the impact of this public health problem. However, further understanding of the pathophysiology of stroke and the underlying genetic pathways is required. The pathological mechanisms of stroke comprise multifaceted molecular cascades regulated by various microRNAs (miRNAs). An increasing number of studies have highlighted the role of miRNAs, which have received much attention during the last decades as an important class of post-transcriptional regulators. It was shown that miRNAs exert their role in the etiology of stroke via mediating excitotoxicity and neuroinflammation. Additionally, miRNAs could be helpful as non-invasive or minimally invasive biomarkers and therapeutic agents. Thus, the current review focused on the interplay of these miRNAs in stroke pathology to upgrade the existing therapeutic strategies.

Docosahexaenoic acid inhibits ischemic stroke to reduce vascular dementia and Alzheimer’s disease

Stroke and dementia are global leading causes of neurological disability and death. The pathology of these diseases is interrelated and they share common, modifiable risk factors. It is suggested that docosahexaenoic acid (DHA) prevents neurological and vascular disorders induced by ischemic stroke and also prevent dementia. The purpose of this study was to review the potential preventative role of DHA against ischemic stroke-induced vascular dementia and Alzheimer's disease. In this review, I analyzed studies on stroke-induced dementia from the PubMed, ScienceDirect, and Web of Science databases as well as studies on the effects of DHA on stroke-induced dementia. As per the results of interventional studies, DHA intake can potentially ameliorate dementia and cognitive function. In particular, DHA derived from foods such as fish oil enters the blood and then migrates to the brain by binding to fatty acid binding protein 5 that is present in cerebral vascular endothelial cells. At this point, the esterified form of DHA produced by lysophosphatidylcholine is preferentially absorbed into the brain instead of free DHA. DHA accumulates in nerve cell membrane and is involved in the prevention of dementia. The antioxidative and anti-inflammatory properties of DHA and DHA metabolites as well as their ability to decrease amyloid beta (Aβ) 42 production were implicated in the improvement of cognitive function. The antioxidant effect of DHA, the inhibition of neuronal cell death by Aβ peptide, improvement in learning ability, and enhancement of synaptic plasticity may contribute to the prevention of dementia induced by ischemic stroke.

Progress on siRNA-based gene therapy targeting secondary injury after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a life-threatening condition with a high mortality rate. For survivors, quality of life is determined by primary and secondary phases of injury. The prospects for injury repair and recovery after ICH are highly dependent on the extent of secondary injury. Currently, no effective treatments are available to prevent secondary injury or its long-term effects. One promising strategy that has recently garnered attention is gene therapy, in particular, small interfering RNAs (siRNA), which silence specific genes responsible for destructive effects after hemorrhage. Gene therapy as a potential treatment for ICH is being actively researched in animal studies. However, there are many barriers to the systemic delivery of siRNA-based therapy, as the use of naked siRNA has limitations. Recently, the Food and Drug Administration approved two siRNA-based therapies, and several are undergoing Phase 3 clinical trials. In this review, we describe the advancements in siRNA-based gene therapy for ICH and also summarize its advantages and disadvantages.

Gut microbes in cerebrovascular diseases: Gut flora imbalance, potential impact mechanisms and promising treatment strategies

The high morbidity, mortality, and disability rates associated with cerebrovascular disease (CeVD) pose a severe danger to human health. Gut bacteria significantly affect the onset, progression, and prognosis of CeVD. Gut microbes play a critical role in gut-brain interactions, and the gut-brain axis is essential for communication in CeVD. The reflection of changes in the gut and brain caused by gut bacteria makes it possible to investigate early warning biomarkers and potential treatment targets. We primarily discussed the following three levels of brain-gut interactions in a systematic review of the connections between gut microbiota and several cerebrovascular conditions, including ischemic stroke, intracerebral hemorrhage, intracranial aneurysm, cerebral small vessel disease, and cerebral cavernous hemangioma. First, we studied the gut microbes in conjunction with CeVD and examined alterations in the core microbiota. This enabled us to identify the focus of gut microbes and determine the focus for CeVD prevention and treatment. Second, we discussed the pathological mechanisms underlying the involvement of gut microbes in CeVD occurrence and development, including immune-mediated inflammatory responses, variations in intestinal barrier function, and reciprocal effects of microbial metabolites. Finally, based on the aforementioned proven mechanisms, we assessed the effectiveness and potential applications of the current therapies, such as dietary intervention, fecal bacterial transplantation, traditional Chinese medicine, and antibiotic therapy.

Optimizing the Time Window of Minimally Invasive Stereotactic Surgery for Intracerebral Hemorrhage Evacuation Combined with Rosiglitazone Infusion Therapy in Rabbits

OBJECTIVE

This study aimed to explore the effects of minimally invasive surgery (MIS) in combination with rosiglitazone (RSG) on intracerebral hemorrhage (ICH) and determine the optimal time window.

METHODS

An ICH rabbit model was constructed using the injection of autologous arterial blood and then treated with RSG, MIS, and MIS combined with RSG at 6, 12, 18, and 24 hours. Thereafter, rabbits that underwent different treatments were used to measure the neurological deficit score, brain water content, and glutamate content. Expression of peroxisome proliferator-activated receptor γ (PPARγ) and CD36 in the different groups was detected using real-time quantitative polymerase chain reaction and Western blotting. In addition, oxidative stress-related and inflammation-related genes were examined.

RESULTS

Brain computed tomography indicated that an ICH rabbit model was successfully established. Compared to those in the control rabbits, the neurological deficit scores, brain water content, and glutamate content in the ICH rabbits were significantly increased at each time window (P < 0.05), while they were decreased at each time window after MIS combined with RSG treatment and declined to the lowest at 6 hours. Additionally, ICH significantly upregulated PPARγ and CD36 expression (P < 0.05). Moreover, superoxide dismutase content decreased after ICH, and nitric oxide synthase 2, tumor necrosis factor-alpha, interleukin-6, and interleukin-1 beta mRNA expression was upregulated, whereas MIS combined with RSG treatment reversed the levels caused by ICH.

CONCLUSIONS

Evacuation of MIS hematoma combined with RSG infusion at an early stage (6 hours) may attenuate secondary brain damage caused by ICH by regulating the PPARγ/CD36 pathway.

Cannabinoids as Glial Cell Modulators in Ischemic Stroke: Implications for Neuroprotection

Stroke is the second leading cause of death worldwide following coronary heart disease. Despite significant efforts to find effective treatments to reduce neurological damage, many patients suffer from sequelae that impair their quality of life. For this reason, the search for new therapeutic options for the treatment of these patients is a priority. Glial cells, including microglia, astrocytes and oligodendrocytes, participate in crucial processes that allow the correct functioning of the neural tissue, being actively involved in the pathophysiological mechanisms of ischemic stroke. Although the exact mechanisms by which glial cells contribute in the pathophysiological context of stroke are not yet completely understood, they have emerged as potentially therapeutic targets to improve brain recovery. The endocannabinoid system has interesting immunomodulatory and protective effects in glial cells, and the pharmacological modulation of this signaling pathway has revealed potential neuroprotective effects in different neurological diseases. Therefore, here we recapitulate current findings on the potential promising contribution of the endocannabinoid system pharmacological manipulation in glial cells for the treatment of ischemic stroke.

Type-I diabetes aggravates post-hemorrhagic stroke cognitive impairment by augmenting oxidative stress and neuroinflammation in mice

Diabetes Mellitus (DM) is a major comorbid condition that increases susceptibility to stroke. Intracerebral hemorrhage (ICH), a devastating type of stroke, accounts for only 13% of the total stroke cases but is associated with higher mortality. Multimorbid models of DM and ischemic stroke have been widely studied; however, fewer pieces of evidence are available on the impact of DM on the outcomes of ICH injury. In this study, we investigated the effect of DM on ICH-induced injury and cognitive impairments. Streptozotocin (STZ) induced type-I DM (T1DM) animal model was used, and experimental ICH was induced by intrastriatal injection of collagenase. Our results demonstrated that DM is associated with a significant increase in hematoma volume and deficits in post-stroke locomotor, sensorimotor, and cognitive behavior in mice. The levels of neuroinflammation, oxidative/nitrosative stress, and glial cell activation were also increased in the diabetic mice following ICH injury. This study provides a better understanding of the influence of DM comorbidity on hemorrhagic stroke outcomes and uncovers the important pathological mechanisms underlying DM-induced exacerbation of ICH injury.

PINK1 antagonize intracerebral hemorrhage by promoting mitochondrial autophagy

BACKGROUND

Intracerebral hemorrhage (ICH) causes neurotransmitter release, oligemia, membrane depolarization, mitochondrial dysfunction, and results in the high rate of mortality and functional disability. Here, we focus on PTEN-induced kinase 1 (PINK1), a mitochondrial-targeted protein kinase, and explore its role in ICH progression.

METHODS

The qPCR and Western blot were performed to examine the expression of PINK1 in ICH patients and mouse model. PINK1 gain- and loss-of-function mice were used to evaluate their protective role on brain injury and behavioral disorders. Flow cytometry was carried out, mitochondrial membrane potential and reactive oxygen species production were detected to explore the distribution and neuroprotective function of PINK1.

RESULTS

PINK1 mRNA was upregulated, however, its protein was downregulated in ICH patients. The reduction of PINK1 was mainly happened in microglial cells in ICH model. Overexpression of PINK1 is able to rescue ICH-induced behavioral disorders. PINK1 protects ICH-induced brain injury by promoting mitochondrial autophagy in microglia.

CONCLUSION

PINK1 possesses a neuroprotective role and antagonizes ICH by promoting mitochondrial autophagy, which may be of value as a therapeutic target for ICH treatment.

Neuroprotective Therapies for Spontaneous Intracerebral Hemorrhage

Patients who survive the initial ictus of spontaneous intracerebral hemorrhage (ICH) remain vulnerable to subsequent injury of the perilesional parenchyma by molecular and cellular responses to the hematoma. Secondary brain injury after ICH, which contributes to long-term functional impairment and mortality, has emerged as an attractive therapeutic target. This review summarizes preclinical and clinical evidence for neuroprotective therapies targeting secondary injury pathways following ICH. A focus on therapies with pleiotropic antiinflammatory effects that target thrombin-mediated chemotaxis and inflammatory cell migration has led to studies investigating statins, anticholinergics, sphingosine-1-phosphate receptor modulators, peroxisome proliferator activated receptor gamma agonists, and magnesium. Attempts to modulate ICH-induced blood-brain barrier breakdown and perihematomal edema formation has prompted studies of nonsteroidal antiinflammatory agents, matrix metalloproteinase inhibitors, and complement inhibitors. Iron chelators, such as deferoxamine and albumin, have been used to reduce the free radical injury that ensues from erythrocyte lysis. Stem cell transplantation has been assessed for its potential to enhance subacute neurogenesis and functional recovery. Despite promising preclinical results of numerous agents, their outcomes have not yet translated into positive clinical trials in patients with ICH. Further studies are necessary to improve our understanding of the molecular events that promote damage and inflammation of the perihematomal parenchyma after ICH. Elucidating the temporal and pathophysiologic features of this secondary brain injury could enhance the clinical efficacy of neuroprotective therapies for ICH.

Tachycardia evoked from insular stroke in rats is dependent on glutamatergic neurotransmission in the dorsomedial hypothalamus

BACKGROUND AND PURPOSE

Damage to the insula results in cardiovascular complications. In rats, activation of N-methyl-d-aspartate receptors (NMDARs) in the intermediate region of the posterior insular cortex (iIC) results in sympathoexcitation, tachycardia and arterial pressure increases. Similarly, focal experimental hemorrhage at the iIC results in a marked sympathetic-mediated increase in baseline heart rate. The dorsomedial hypothalamic region (DMH) is critical for the integration of sympathetic-mediated tachycardic responses. Here, whether responses evoked from the iIC are dependent on a synaptic relay in the DMH was evaluated.

METHODS

Wistar rats were prepared for injections into the iIC and DMH. Anatomical (tracing combined with immunofluorescence) and functional experiments (cardiovascular and sympathetic recordings) were performed.

RESULTS

The iIC sends dense projections to the DMH. Approximately 50% of iIC neurons projecting to the DMH express NMDARs, NR1 subunit. Blockade of glutamatergic receptors in the DMH abolishes the cardiovascular and autonomic responses evoked by the activation of NMDARs in the iIC (change in mean arterial pressure 7 ± 1 vs. 1 ± 1 mmHg after DMH blockade; change in heart rate 28 ± 3 vs. 0 ± 3 bpm after DMH blockade; change in renal sympathetic nerve activity 23% ± 1% vs. -1% ± 4% after DMH blockade). Experimental hemorrhage at the iIC resulted in a marked tachycardia (change 89 ± 14 bpm) that was attenuated by 65% ± 5% (p = 0.0009) after glutamatergic blockade at the DMH.

CONCLUSIONS

The iIC-induced tachycardia is largely dependent upon a glutamatergic relay in the DMH. Our study reveals the presence of an excitatory glutamatergic pathway from the iIC to the DMH that may be involved in the cardiovascular alterations observed after insular stroke.

Neuritin improves the neurological functional recovery after experimental intracerebral hemorrhage in mice

Stroke is one of the leading causes of death worldwide, with intracerebral hemorrhage (ICH) being the most lethal subtype. Neuritin (Nrn) is a neurotropic factor that has been reported to have neuroprotective effects in acute brain and spinal cord injury. However, whether Nrn has a protective role in ICH has not been investigated. In this study, ICH was induced in C57BL/6 J mice by injection of collagenase VII, while the overexpression of Nrn in the striatum was induced by an adeno-associated virus serotype 9 (AAV9) vector. We found that compared with GFP-ICH mice, Nrn-ICH mice showed improved performance in the corner, cylinder and forelimb tests after ICH, and showed less weight loss and more rapid weight recovery. Overexpression of Nrn reduced brain lesions, edema, neuronal death and white matter and synaptic integrity dysfunction caused by ICH. Western blot results showed that phosphorylated PERK and ATF4 were significantly inhibited, while phosphorylation of Akt/mammalian target of rapamycin was increased in the Nrn-ICH group, compared with the GFP-ICH group. Whole cell recording from motor neurons indicated that overexpression of Nrn reversed the decrease of spontaneous excitatory postsynaptic currents (sEPSCs) and action potential frequencies induced by ICH. These data show that Nrn improves neurological deficits in mice with ICH by reducing brain lesions and edema, inhibiting neuronal death, and possibly by increasing neuronal connections.

Metabolic Insight Into the Neuroprotective Effect of Tao-He-Cheng-Qi (THCQ) Decoction on ICH Rats Using Untargeted Metabolomics

Tao-He-Cheng-Qi decoction (THCQ) is an effective traditional Chinese medicine used to treat intracerebral hemorrhage (ICH). This study was performed to investigate the possible neuroprotective effect of THCQ decoction on secondary brain damage in rats with intracerebral hemorrhage and to elucidate the potential mechanism based on a metabolomics approach. Sprague-Dawley (SD) rats were randomly divided into five groups: the sham group, collagenase-induced ICH model group, THCQ low-dose (THCQ-L)-treated group, THCQ moderate-dose (THCQ-M)-treated group and THCQ high-dose (THCQ-H)-treated group. Following 3 days of treatment, behavioral changes and histopathological lesions in the brain were estimated. Untargeted metabolomics analysis with multivariate statistics was performed by using ultrahigh-performance liquid chromatography–mass spectrometry (UPLC-Q-Exactive Orbitrap MS). THCQ treatment at two dosages (5.64 and 11.27 g/kg·d) remarkably improved behavior (p < 0.05), brain water content (BMC) and hemorheology (p < 0.05) and improved brain nerve tissue pathology and inflammatory infiltration in ICH rats. Moreover, a metabolomic analysis demonstrated that the serum metabolic profiles of ICH patients were significantly different between the sham group and the ICH-induced model group. Twenty-seven biomarkers were identified that potentially predict the clinical benefits of THCQ decoction. Of these, 4 biomarkers were found to be THCQ-H group-specific, while others were shared between two clusters. These metabolites are mainly involved in amino acid metabolism and glutamate-mediated cell excitotoxicity, lipid metabolism-mediated oxidative stress, and mitochondrial dysfunction caused by energy metabolism disorders. In addition, a correlation analysis showed that the behavioral scores, brain water content and hemorheology were correlated with levels of serum metabolites derived from amino acid and lipid metabolism. In conclusion, the results indicate that THCQ decoction significantly attenuates ICH-induced secondary brain injury, which could be mediated by improving metabolic disorders in cerebral hemorrhage rats.

Umbilical cord-derived MSC and hyperbaric oxygen therapy effectively protected the brain in rat after acute intracerebral haemorrhage

This study tested the hypothesis that combined therapy with human umbilical cord‐derived mesenchymal stem cells (HUCDMSCs) and hyperbaric oxygen (HBO) was superior to either one on preserving neurological function and reducing brain haemorrhagic volume (BHV) in rat after acute intracerebral haemorrhage (ICH) induced by intracranial injection of collagenase. Adult male SD rats (n = 30) were equally divided into group 1 (sham‐operated control), group 2 (ICH), group 3 (ICH +HUCDMSCs/1.2 × 10⁶ cells/intravenous injection at 3h and days 1 and 2 after ICH), group 4 (ICH +HBO/at 3 hours and days 1 and 2 after ICH) and group 5 (ICH +HUCDMSCs‐HBO), and killed by day 28 after ICH. By day 1, the neurological function was significantly impaired in groups 2‐5 than in group 1 (P < .001), but it did not differ among groups 2 to 5. By days 7, 14 and 28, the integrity of neurological function was highest in group 1, lowest in group 2 and significantly progressively improved from groups 3 to 5 (all P < .001). By day 28, the BHV was lowest in group 1, highest in group 2 and significantly lower in group 5 than in groups 3/4 (all P < .0001). The protein expressions of inflammation (HMGB1/TLR‐2/TLR‐4/MyD88/TRAF6/p‐NF‐κB/IFN‐γ/IL‐1ß/TNF‐α), oxidative stress/autophagy (NOX‐1/NOX‐2/oxidized protein/ratio of LC3B‐II/LC3B‐I) and apoptosis (cleaved‐capspase3/PARP), and cellular expressions of inflammation (CD14+, F4/80+) in brain tissues exhibited an identical pattern, whereas cellular levels of angiogenesis (CD31+/vWF+/small‐vessel number) and number of neurons (NeuN+) exhibited an opposite pattern of BHV among the groups (all P < .0001). These results indicate that combined HUCDMSC‐HBO therapy offered better outcomes after rat ICH.

The Negative Allosteric Modulator EU1794-4 Reduces Single-Channel Conductance and Ca2+ Permeability of GluN1/GluN2A N-Methyl-d-Aspartate Receptors

NMDA receptors are ligand-gated ion channels that mediate a slow, Ca2+-permeable component of excitatory synaptic currents. These receptors are involved in several important brain functions, including learning and memory, and have also been implicated in neuropathological conditions and acute central nervous system injury, which has driven therapeutic interest in their modulation. The EU1794 series of positive and negative allosteric modulators of NMDA receptors has structural determinants of action near the preM1 helix that is involved in channel gating. Here, we describe the effects of the negative allosteric modulator EU1794-4 on GluN1/GluN2A channels studied in excised outside-out patches. Coapplication of EU1794-4 with a maximally effective concentration of glutamate and glycine increases the fraction of time the channel is open by nearly 1.5-fold, yet reduces single-channel conductance by increasing access of the channel to several subconductance levels, which has the net overall effect of reducing the macroscopic current. The lack of voltage-dependence of negative modulation suggests this is unrelated to a channel block mechanism. As seen with other NMDA receptor modulators that reduce channel conductance, EU1794-4 also reduces the Ca2+ permeability relative to monovalent cations of GluN1/GluN2A receptors. We conclude that EU1794-4 is a prototype for a new class of NMDA receptor negative allosteric modulators that reduce both the overall current that flows after receptor activation and the flux of Ca2+ ion relative to monovalent cations. SIGNIFICANCE STATEMENT: NMDA receptors are implicated in many neurological conditions but are challenging to target given their ubiquitous expression. Several newly identified properties of the negative allosteric modulator EU1794-4, including reducing Ca2+ flux through NMDA receptors and attenuating channel conductance, explain why this modulator reduces but does not eliminate NMDA receptor function. A modulator with these properties could have therapeutic advantages for indications in which attenuation of NMDA receptor function is beneficial, such as neurodegenerative disease and acute injury.

Neuroregeneration and functional recovery after stroke: advancing neural stem cell therapy toward clinical application

Stroke is a main cause of death and disability worldwide. The ability of the brain to self-repair in the acute and chronic phases after stroke is minimal; however, promising stem cell-based interventions are emerging that may give substantial and possibly complete recovery of brain function after stroke. Many animal models and clinical trials have demonstrated that neural stem cells (NSCs) in the central nervous system can orchestrate neurological repair through nerve regeneration, neuron polarization, axon pruning, neurite outgrowth, repair of myelin, and remodeling of the microenvironment and brain networks. Compared with other types of stem cells, NSCs have unique advantages in cell replacement, paracrine action, inflammatory regulation and neuroprotection. Our review summarizes NSC origins, characteristics, therapeutic mechanisms and repair processes, then highlights current research findings and clinical evidence for NSC therapy. These results may be helpful to inform the direction of future stroke research and to guide clinical decision-making.

Surgical Management of Trauma-Related Intracranial Hemorrhage-a Review

PURPOSE OF REVIEW

The surgical management of trauma-related intracranial hemorrhage is characterized by marked heterogeneity. Large prospective randomized trials have generally been prohibited by the ubiquity of concordant pathology, diversity of trauma systems, and paucity of clinical equipoise among providers.

RECENT FINDINGS

To date, the results of retrospective studies and surgeon preference have driven the indications, modality, extent, and timing of surgical intervention in the global neurosurgical community. With advances in our understanding of the pathophysiology of hemorrhagic TBI and the advent of novel surgical techniques, a reevaluation of surgical indication, timing, and approach is warranted. In this way, we can work to optimize surgical outcomes, achieving maximal functional recovery while minimizing surgical morbidity.

Pathophysiology and Treatment of Stroke: Present Status and Future Perspectives

Stroke is the second leading cause of death and a major contributor to disability worldwide. The prevalence of stroke is highest in developing countries, with ischemic stroke being the most common type. Considerable progress has been made in our understanding of the pathophysiology of stroke and the underlying mechanisms leading to ischemic insult. Stroke therapy primarily focuses on restoring blood flow to the brain and treating stroke-induced neurological damage. Lack of success in recent clinical trials has led to significant refinement of animal models, focus-driven study design and use of new technologies in stroke research. Simultaneously, despite progress in stroke management, post-stroke care exerts a substantial impact on families, the healthcare system and the economy. Improvements in pre-clinical and clinical care are likely to underpin successful stroke treatment, recovery, rehabilitation and prevention. In this review, we focus on the pathophysiology of stroke, major advances in the identification of therapeutic targets and recent trends in stroke research.

Neuroprotective Methodologies of Co-Enzyme Q10 Mediated Brain Hemorrhagic Treatment: Clinical and Pre-Clinical Findings

Cerebral brain hemorrhage is associated with the highest mortality and morbidity despite only constituting approximately 10-15% of all strokes classified into intracerebral and intraventricular hemorrhage where most of the patients suffer from impairment in memory, weakness or paralysis in arms or legs, headache, fatigue, gait abnormality and cognitive dysfunctions. Understanding molecular pathology and finding the worsening cause of hemorrhage will lead to explore the therapeutic interventions that could prevent and cure the disease. Mitochondrial ETC-complexes dysfunction has been found to increase neuroinflammatory cytokines, oxidative free radicals, excitotoxicity, neurotransmitter and energy imbalance that are the key neuropathological hallmarks of cerebral hemorrhage. Coenzyme Q10 (CoQ10), as a part of the mitochondrial respiratory chain can effectively restore these neuronal dysfunctions by preventing the opening of mitochondrial membrane transition pore, thereby counteracting cell death events as well as exerts an anti-inflammatory effect by influencing the expression of NF-kB1 dependent genes thus preventing the neuroinflammation and energy restoration. Due to behavior and biochemical heterogeneity in post cerebral brain hemorrhagic pattern different preclinical autologous blood injection models are required to precisely investigate the forthcoming therapeutic strategies. Despite emerging pre-clinical research and resultant large clinical trials for promising symptomatic treatments, there are very less pharmacological interventions demonstrated to improve post operative condition of patients where intensive care is required. Therefore, in current review, we explore the disease pattern, clinical and pre-clinical interventions under investigation and neuroprotective methodologies of CoQ10 precursors to ameliorate post brain hemorrhagic conditions.

Autonomic and cardiovascular consequences resulting from experimental hemorrhagic stroke in the left or right intermediate insular cortex in rats

Damage to the insular cortex (IC) results in serious cardiovascular consequences and evidence indicates that the characteristics are lateralized. However, a study comparing the effects of focal experimental hemorrhage between IC sides was never performed. We compared the cardiovascular, autonomic and cardiac changes produced by focal experimental hemorrhage (ICH) into the left (L) or right (R) IC. Wistar rats were submitted to microinjection of autologous blood (ICH) or saline (n = 6 each side/group) into the R or L IC. Blood pressure (BP), heart rate (HR) and renal sympathetic activity (RSNA) were recorded. Measurements of calcium transient and sarcoplasmic Ca²⁺ ATPase expression in cardiomyocytes were performed. ICH increased baseline HR (Δ:L-ICH 452 ± 13 vs saline 407 ± 11 bpm; R-ICH 450 ± 7 vs saline 406 ± 8 bpm, P < 0.05) without changing BP. HR was restored to baseline levels after i.v. atenolol. Strikingly, ICH rats presented a reduced baseline RSNA (Δ:L-ICH 122 ± 4 vs saline 148 ± 11 spikes/s; R-ICH 112 ± 5 vs saline 148 ± 7 spikes/s, P < 0.05). After 24 h of ICH we observed a marked increase in cardiac ectopies and this number was greater after ICH R-IC. Heart weight, calcium amplitude and SERCA expression were reduced only in ICH R-IC. Focal stroke into IC can alter the cardiac and renal autonomic control. Damage to the R-IC produces a greater number of arrhythmias and changes in calcium dynamics in cardiac cells indicating that the cardiovascular consequences are hemisphere-dependent. These findings confirm asymmetry for cardiac autonomic control at the IC and help to understand the cardiac and renal implications observed after specific side cortical damage.

Neuroprotective potential of solanesol in a combined model of intracerebral and intraventricular hemorrhage in rats

Intracerebral hemorrhage (ICH) may be caused by trauma, aneurysm and arteriovenous malformation, as can any bleeding within the intracranial vault, including brain parenchyma and adjacent meningeal spaces (aneurism and atreovenous malformation). ICH is the cerebral stroke with the least treatable form. Over time, intraventricular hemorrhage (IVH) is associated with ICH, which contributes to hydrocephalus, and the major cause of most hemorrhagic death (Due to the cerebral hemorrhage and post hemorrhagic surgeries). Most patients suffer from memory impairment, grip strength, posture, and cognitive dysfunctions attributable to cerebral hemorrhage or post-brain hemorrhagic surgery. Nevertheless, a combined model of ICH based IVH is not present pre-clinically. Autologous blood (ALB) injection (20 μl/5 min) in the rat brain triggers hemorrhage, such as factors that further interfere with the normal functioning of neuroinflammatory cytokines, oxidative stress, and neurotransmitter dysfunction, such as CoQ10 insufficiency and dysregulation of mitochondrial ETC-complexes. For the prevention of post-brain hemorrhagic behavioral and neurochemical dysfunctions, there is no specific drug treatment available, only available therapy used to provide symptomatic relief. The current study reveals that long-term administration of Solanesol (SNL) 40 and 60 mg/kg alone and in combination with available drug therapy Donepezil (DNP) 3 mg/kg, Memantine (MEM) 20 mg/kg, Celecoxib (CLB) 20 mg/kg, Pregabalin (PGB) 30 mg/kg, may provide the neuroprotective effect by improving behavioral and neurochemical deficits, and gross pathological changes in ALB induced combined experimental model of ICH-IVH in post brain hemorrhagic conditions in rats. Thus, SNL can be a potential therapeutic approach to improve neuronal mitochondrial dysfunction associated with post brain hemorrhagic behavioral and neurochemical alterations.

BM-MSC Transplantation Alleviates Intracerebral Hemorrhage-Induced Brain Injury, Promotes Astrocytes Vimentin Expression, and Enhances Astrocytes Antioxidation via the Cx43/Nrf2/HO-1 Axis

Intracerebral hemorrhage (ICH) is a particularly severe form of stroke, and reactive astrogliosis is a common response following injury to the central nervous system (CNS). Mesenchymal stem cells (MSCs) are reported to promote neurogenesis and alleviate the late side effects in injured brain regions. Gap junctions (Gjs) are abundant in the brain, where the richest connexin (Cx) is Cx43, most prominently expressed in astrocytes. Nuclear factor erythroid 2-related factor 2 (Nrf2) is an essential transcription factor regulating antioxidant reactions. Here, we aimed to explore whether bone marrow MSCs (BM-MSCs) could alleviate brain injury and protect astrocytes from apoptosis, by regulating Cx43 and Nrf2. We validated the effect of BM-MSC transplantation in an ICH model in vivo and in vitro and detected changes using immunofluorescence, as well as protein and mRNA expression of glial fibrillary acidic protein (GFAP), vimentin (VIM), Cx43, Nrf2, and heme oxygenase-1 (HO-1). Our results showed that BM-MSC transplantation attenuated brain injury after ICH and upregulated VIM expression in vivo and in vitro. Additionally, Cx43 upregulation and Nrf2 nuclear translocation were observed in astrocytes cocultured with BM-MSC. Knockdown of Cx43 by siRNA restrained Nrf2 nuclear translocation. Cx43 and Nrf2 had a connection as determined by immunofluorescence and coimmunoprecipitation. We demonstrated that astrocytes undergo astroglial-mesenchymal phenotype switching and have anti-apoptotic abilities after BM-MSC transplantation, where Cx43 upregulation triggers Nrf2 nuclear translocation and promotes its phase II enzyme expression. The Cx43/Nrf2 interaction of astrocytes after BM-MSC transplantation may provide an important therapeutic target in the management of ICH.

Matrix Metalloproteinases in Acute Intracerebral Hemorrhage

Spontaneous intracerebral hemorrhage (ICH) accounts for 10-30% of all strokes and affects more than one million people every year worldwide, and it is the stroke subtype associated with the highest rates of mortality and residual disability. So far, clinical trials have mainly targeted primary cerebral injury and have substantially failed to improve clinical outcomes. The understanding of the pathophysiology of early and delayed injury after ICH is, hence, of paramount importance to identify potential targets of intervention and develop effective therapeutic strategies. Matrix metalloproteinases (MMPs) represent a ubiquitous superfamily of structurally related zinc-dependent endopeptidases able to degrade any component of the extracellular matrix. They are upregulated after ICH, in which different cell types, including leukocytes, activated microglia, neurons, and endothelial cells, are involved in their synthesis and secretion. The aim of this review is to summarize the available experimental and clinical evidence about the role of MMPs in brain injury following spontaneous ICH and provide critical insights into the underlying mechanisms.

Using Serum Amino Acids to Predict Traumatic Brain Injury: A Systematic Approach to Utilize Multiple Biomarkers

Traumatic brain injury (TBI) can cause biochemical and metabolomic alterations in the brain tissue and serum. These alterations can be used for diagnosis and prognosis of TBI. Here, the serum concentrations of seventeen amino acids (AA) were studied for their potential utility as biomarkers of TBI. Twenty-five female, 4-week-old piglets received diffuse (n = 13) or focal (n = 12) TBI. Blood samples were obtained both pre-injury and at either 24-h or 4-days post-TBI. To find a robust panel of biomarkers, the results of focal and diffuse TBIs were combined and multivariate logistic regression analysis, coupled with the best subset selection technique and repeated k-fold cross-validation method, was used to perform a thorough search of all possible subsets of AAs. The combination of serum glycine, taurine, and ornithine was optimal for TBI diagnosis, with 80% sensitivity and 86% overall prediction rate, and showed excellent TBI diagnostic performance, with 100% sensitivity and 78% overall prediction rate, on a separate validation dataset including four uninjured and five injured animals. We found that combinations of biomarkers outperformed any single biomarker. We propose this 3-AA serum biomarker panel to diagnose mild-to-moderate focal/diffuse TBI. The systematic approaches implemented herein can be used for combining parameters from various TBI assessments to develop/evaluate optimal multi-factorial diagnostic/prognostic TBI metrics.

Poly-arginine-18 peptides do not exacerbate bleeding, or improve functional outcomes following collagenase-induced intracerebral hemorrhage in the rat

Background

Cationic arginine-rich peptides (CARPs) have demonstrated neuroprotective and/or behavioural efficacy in ischemic and hemorrhagic stroke and traumatic brain injury models. Therefore, in this study we investigated the safety and neuroprotective efficacy of the CARPs poly-arginine-18 (R18; 18-mer of arginine) and its D-enantiomer R18D given in the acute bleeding phase in an intracerebral hemorrhage (ICH) model.

Methods

One hundred and fifty-eight male Sprague-Dawley rats received collagenase-induced ICH. Study 1 examined various doses of R18D (30, 100, 300, or 1000 nmol/kg) or R18 (100, 300, 1000 nmol/kg) administered intravenously 30 minutes post-collagenase injection on hemorrhage volume 24 hours after ICH. Study 2 examined R18D (single intravenous dose) or R18 (single intravenous dose, plus 6 daily intraperitoneal doses) at 300 or 1000 nmol/kg commencing 30 minutes post-collagenase injection on behavioural outcomes (Montoya staircase test, and horizontal ladder test) in the chronic post-ICH period. A histological assessment of tissue loss was assessed using a Nissl stain at 28 days after ICH.

Results

When administered during ongoing bleeding, neither R18 or R18D exacerbated hematoma volume or worsened functional deficits. Lesion volume assessment at 28 days post-ICH was not reduced by the peptides; however, animals treated with the lower R18D 300 nmol/kg dose, but not with the higher 1000 nmol/kg dose, demonstrated a statistically increased lesion size compared to saline treated animals.

Conclusion

Overall, both R18 and R18D appeared to be safe when administered during a period of ongoing bleeding following ICH. Neither peptide appears to have any statistically significant effect in reducing lesion volume or improving functional recovery after ICH. Additional studies are required to further assess dose efficacy and safety in pre-clinical ICH studies.

Role and mechanisms of cytokines in the secondary brain injury after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a common and severe cerebrovascular disease that has high mortality. Few survivors achieve self-care. Currently, patients receive only symptomatic treatment for ICH and benefit poorly from this regimen. Inflammatory cytokines are important participants in secondary injury after ICH. Increases in proinflammatory cytokines may aggravate the tissue injury, whereas increases in anti-inflammatory cytokines might be protective in the ICH brain. Inflammatory cytokines have been studied as therapeutic targets in a variety of acute and chronic brain diseases; however, studies on ICH are limited. This review summarizes the roles and functions of various pro- and anti-inflammatory cytokines in secondary brain injury after ICH and discusses pathogenic mechanisms and emerging therapeutic strategies and directions for treatment of ICH.

Evolutionary concept of inflammatory response and stroke

The immune system plays an important role under both physiological and pathological conditions. Immune surveillance as well as defense and healing processes are crucial for the organism, but the immune system has a natural tendency to act aggressively when excessively stimulated. We may assume that the immune system is not designed to deal with severe conditions, such as polytrauma or severe stroke, because these are not compatible with life in the wilderness and evolution has no chance to act in such cases. These conditions are associated with exaggerated/deregulated inflammatory response, which may cause more damage than initial pathology. In this article, we would like to sketch a basic concept of the immune system-brain interactions from the evolutionary point of view and to discuss some implications related to stroke.

Acute hypertensive response in patients with intracerebral hemorrhage pathophysiology and treatment

Acute hypertensive response is a common systemic response to occurrence of intracerebral hemorrhage which has gained unique prominence due to high prevalence and association with hematoma expansion and increased mortality. Presumably, the higher systemic blood pressure predisposes to continued intraparenchymal hemorrhage by transmission of higher pressure to the damaged small arteries and may interact with hemostatic and inflammatory pathways. Therefore, intensive reduction of systolic blood pressure has been evaluated in several clinical trials as a strategy to reduce hematoma expansion and subsequent death and disability. These trials have demonstrated either a small magnitude benefit (second intensive blood pressure reduction in acute cerebral hemorrhage trial and efficacy of nitric oxide in stroke trial) or no benefit (antihypertensive treatment of acute cerebral hemorrhage 2 trial) with intensive systolic blood pressure reduction compared with modest or standard blood pressure reduction. The differences may be explained by the variation in intensity of systolic blood pressure reduction between trials. A treatment threshold of systolic blood pressure of ≥180 mm with the target goal of systolic blood pressure reduction to values between 130 and 150 mm Hg within 6 h of symptom onset may be best supported by current evidence.

Increased Expression of Apo-J and Omi/HtrA2 After Intracerebral Hemorrhage in Rats

OBJECTIVE

To investigate the changes of Apo-J and Omi/HtrA2 protein expression in rats with intracerebral hemorrhage.

METHODS

150 Sprague-Dawley adult rats were randomly divided into 3 groups: (1) normal control (NC) group, (2) sham group, and (3) intracerebral hemorrhage (ICH) group. The data were collected at 6 hours, 12 hours, 1 day, 2 days, 3 days, 5 days, and 7 days. Apoptosis was measured by terminal deoxynucleotidyl transferase-mediated biotinylated-dUTP nick-end labeling staining. The distributions of the Apo-J and Omi/HtrA2 proteins were determined by immunohistochemical staining. The levels of Apo-J mRNA and Omi/HtrA2 mRNA expressions were examined by real-time polymerase chain reaction.

RESULTS

Apoptosis in the ICH group was higher than in the sham and NC groups (P < 0.05). Both the Apo-J and Omi/HtrA2 expression levels were increased in the peripheral region of hemorrhage, with a peak at 3 days. The Apo-J mRNA level positively correlated with the HtrA2 mRNA level in the ICH group (r = 0.883, P < 0.001).

CONCLUSION

The expressions of Apo-J and Omi/HtrA2 increased in parallel in the peripheral region of rat cerebral hemorrhage. Local high expression of Apo-J in the peripheral regions may play a neuroprotective role by inhibiting apoptosis via the Omi/HtrA2 pathway after hemorrhage.

Optimized tPA: A non-neurotoxic fibrinolytic agent for the drainage of intracerebral hemorrhages

Intracerebral hemorrhage (ICH) is the most severe form of stroke. Catheter-delivered thrombolysis with recombinant tissue-type plasminogen activator (rtPA) for the drainage of ICH is currently under evaluation in a phase III clinical trial (MISTIE III). However, in a pig model of ICH, in situ fibrinolysis with rtPA was reported to increase peri-lesional edema by promoting N-methyl-D-aspartate (NMDA)-dependent excitotoxicity. In the present study, we engineered a non-neurotoxic tPA variant, OptPA, and investigated its safety and efficacy for in situ fibrinolysis in a rat model of ICH. Magnetic resonance imaging analyses of hematoma and edema volumes, behavioral tasks and histological analyses were performed to measure the effects of treatments. In vitro, OptPA was equally fibrinolytic as rtPA without promoting NMDA-dependent neurotoxicity. In vivo, in situ fibrinolysis using OptPA reduced hematoma volume, like rtPA, but it also reduced the evolution of peri-hematomal neuronal death and subsequent edema progression. Overall, this preclinical study demonstrates beneficial effects of OptPA compared to rtPA for the drainage of ICH.

Targeting the Nrf2-Heme Oxygenase-1 Axis after Intracerebral Hemorrhage

BACKGROUND

Injury to cells adjacent to an intracerebral hemorrhage (ICH) is likely mediated at least in part by toxins released from the hematoma that initiate complex and interacting injury cascades. Pharmacotherapies targeting a single toxin or pathway, even if consistently effective in controlled experimental models, have a high likelihood of failure in a variable clinical setting. Nuclear factor erythroid-2 related factor 2 (Nrf2) regulates the expression of heme oxygenase-1 (HO-1) and multiple other proteins with antioxidant and antiinflammatory effects, and may be a target of interest after ICH.

METHODS

Studies that tested the effect of HO and Nrf2 in models relevant to ICH are summarized, with an effort to reconcile conflicting data by consideration of methodological limitations.

RESULTS

In vitro studies demonstrated that Nrf2 activators rapidly increased HO-1 expression in astrocytes, and reduced their vulnerability to hemoglobin or hemin. Modulating HO-1 expression via genetic approaches yielded similar results. Systemic treatment with small molecule Nrf2 activators increased HO-1 expression in perivascular cells, particularly astrocytes. When tested in mouse or rat ICH models, Nrf2 activators were consistently protective, improving barrier function and attenuating edema, inflammation, neuronal loss and neurological deficits. These effects were mimicked by selective astrocyte HO-1 overexpression in transgenic mice.

CONCLUSION

Systemic treatment with Nrf2 activators after ICH is protective in rodents. Two compounds, dimethyl fumarate and hemin, are currently approved for treatment of multiple sclerosis and acute porphyria, respectively, and have acceptable safety profiles over years of clinical use. Further development of these drugs as ICH therapeutics seems warranted.

Pannexin-1 is involved in neuronal apoptosis and degeneration in experimental intracerebral hemorrhage in rats

Pannexins serve an important role in the regulation of extracellular neuronal regenerative currents and cellular signal transduction of glial cells; however, the effects of pannexins in various cerebrovascular diseases have not been reported. The present study focused on the expression and influence of pannexins in a rat model of intracerebral hemorrhage (ICH), and confirmed that pannexins (including Pannexin‑1, Pannexin‑2 and Pannexin‑3) are expressed in rat brain tissues. However, only the expression of Pannexin‑1 was significantly increased and peaked 48 h post‑ICH. Following treatment with carbenoxolone (CBX), which is an inhibitor of Pannexin‑1, apoptosis and neuronal degeneration in the brain tissues around the ICH hematoma decreased. The extent of secondary brain injury due to ICH was also alleviated. Compared with rats in the ICH‑only group, recovery of neurocognitive functions improved significantly in the CBX‑treated groups. Results from the present study suggested that the upregulation of Pannexin‑1 expression may be involved in apoptosis and degeneration of neurons in the rat brain following ICH, and may contribute to subsequent cognitive dysfunction.

The Role of Inflammatory Response in Stroke Associated Programmed Cell Death

Stroke represents devastating pathology which is associated with a high morbidity and mortality. Initial damage caused directly by the onset of stroke, primary injury, may be eclipsed by secondary injury which may have a much more devastating effect on the brain. Primary injury is predominantly associated with necrotic cell death due to fatal insufficiency of oxygen and glucose. Secondary injury may on the contrary, lead apoptotic cell death due to structural damage which is not compatible with cellular functions or which may even represent the danger of malign transformation. The immune system is responsible for surveillance, defense and healing processes and the immune system plays a major role in triggering programmed cell death. Severe pathologies, such as stroke, are often associated with deregulation of the immune system, resulting in aggravation of secondary brain injury. The goal of this article is to overview the current knowledge about the role of immune system in the pathophysiology of stroke with respect to programmed neuronal cell death as well as to discuss current therapeutic strategies targeting inflammation after stroke.

Homeostasis of the Intraparenchymal-Blood Glutamate Concentration Gradient: Maintenance, Imbalance, and Regulation

It is widely accepted that glutamate is the most important excitatory neurotransmitter in the central nervous system (CNS). However, there is also a large amount of glutamate in the blood. Generally, the concentration gradient of glutamate between intraparenchymal and blood environments is stable. However, this gradient is dramatically disrupted under a variety of pathological conditions, resulting in an amplifying cascade that causes a series of pathological reactions in the CNS and peripheral organs. This eventually seriously worsens a patient’s prognosis. These two “isolated” systems are rarely considered as a whole even though they mutually influence each other. In this review, we summarize what is currently known regarding the maintenance, imbalance and regulatory mechanisms that control the intraparenchymal-blood glutamate concentration gradient, discuss the interrelationships between these systems and further explore their significance in clinical practice.

Effect of emergency medical service use on time interval from symptom onset to hospital admission for definitive care among patients with intracerebral hemorrhage: a multicenter observational study

Objective

This study evaluated whether emergency medical service (EMS) use was associated with early arrival and admission for definitive care among intracerebral hemorrhage (ICH) patients.

Methods

Patients with ICH were enrolled from 29 hospitals between November 2007 and December 2012, excluding those patients with subarachnoid hemorrhage, traumatic ICH, and missing information. The patients were divided into four groups based on visit type to the definitive hospital emergency department (ED): direct visit by EMS (EMS-direct), direct visit without EMS (non-EMS-direct), transferred from a primary hospital by EMS (EMS-transfer), and transferred from a primary hospital without EMS (non-EMS-transfer). The outcomes were the proportions of participants within early (<1 hr) definitive hospital ED arrival from symptom onset (pS2ED) and those within early (<4 hr) admission from symptom onset (pS2AD). Adjusted odds ratios were calculated to determine the association between EMS use and outcomes with and without inter-hospital transfer.

Results

A total of 6,564 patients were enrolled. The adjusted odds ratios (95% confidence intervals) for pS2ED were 22.95 (17.73–29.72), 1.11 (0.67–1.84), and 7.95 (6.04–10.46) and those for pS2AD were 5.56 (4.70–6.56), 0.96 (0.71–1.30), and 2.35 (1.94–2.84) for the EMS-direct, EMS-transfer, and non-EMS-direct groups compared with the non-EMS-transfer group, respectively. Through the interaction model, EMS use was significantly associated with early arrival and admission among direct visiting patients but not with transferred patients.

Conclusion

EMS use was significantly associated with shorter time intervals from symptom onset to arrival and admission at a definitive care hospital. However, the effect disappeared when patients were transferred from a primary hospital.

White Matter Injury after Intracerebral Hemorrhage: Pathophysiology and Therapeutic Strategies

Intracerebral hemorrhage (ICH) accounts for 10%–30% of all types of stroke. Bleeding within the brain parenchyma causes gray matter (GM) destruction as well as proximal or distal white matter (WM) injury (WMI) due to complex pathophysiological mechanisms. Because WM has a distinct cellular architecture, blood supply pattern and corresponding function, and its response to stroke may vary from that of GM, a better understanding of the characteristics of WMI following ICH is essential and may shed new light on treatment options. Current evidence using histological, radiological and chemical biomarkers clearly confirms the spatio-temporal distribution of WMI post- ICH. Although certain types of pathological damage such as inflammatory, oxidative and neuro-excitotoxic injury to WM have been identified, the exact molecular mechanisms remain unclear. In this review article, we briefly describe the constitution and physiological function of brain WM, summarize evidence regarding WMI, and focus on the underlying pathophysiological mechanisms and therapeutic strategies.

Secondary Hematoma Expansion and Perihemorrhagic Edema after Intracerebral Hemorrhage: From Bench Work to Practical Aspects

Intracerebral hemorrhages (ICH) represent about 10-15% of all strokes per year in the United States alone. Key variables influencing the long-term outcome after ICH are hematoma size and growth. Although death may occur at the time of the hemorrhage, delayed neurologic deterioration frequently occurs with hematoma growth and neuronal injury of the surrounding tissue. Perihematoma edema has also been implicated as a contributing factor for delayed neurologic deterioration after ICH. Cerebral edema results from both blood-brain barrier disruption and local generation of osmotically active substances. Inflammatory cellular mediators, activation of the complement, by-products of coagulation and hemolysis such as thrombin and fibrin, and hemoglobin enter the brain and induce a local and systemic inflammatory reaction. These complex cascades lead to apoptosis or neuronal injury. By identifying the major modulators of cerebral edema after ICH, a therapeutic target to counter degenerative events may be forthcoming.

Biochemical changes in the injured brain

Brain metabolism is an energy intensive phenomenon involving a wide spectrum of chemical intermediaries. Various injury states have a detrimental effect on the biochemical processes involved in the homeostatic and electrophysiological properties of the brain. The biochemical markers of brain injury are a recent addition in the armamentarium of neuro-clinicians and are being increasingly used in the routine management of neuro-pathological entities such as traumatic brain injury, stroke, subarachnoid haemorrhage and intracranial space occupying lesions. These markers are increasingly being used in assessing severity as well as in predicting the prognostic course of neuro-pathological lesions. S-100 protein, neuron specific enolase, creatinine phosphokinase isoenzyme BB and myelin basic protein are some of the biochemical markers which have been proven to have prognostic and clinical value in the brain injury. While S-100, glial fibrillary acidic protein and ubiquitin C terminal hydrolase are early biomarkers of neuronal injury and have the potential to aid in clinical decision-making in the initial management of patients presenting with an acute neuronal crisis, the other biomarkers are of value in predicting long-term complications and prognosis in such patients. In recent times cerebral microdialysis has established itself as a novel way of monitoring brain tissue biochemical metabolites such as glucose, lactate, pyruvate, glutamate and glycerol while small non-coding RNAs have presented themselves as potential markers of brain injury for future.

Epidemiology, Risk Factors, and Clinical Features of Intracerebral Hemorrhage: An Update

Intracerebral hemorrhage (ICH) is the second most common subtype of stroke and a critical disease usually leading to severe disability or death. ICH is more common in Asians, advanced age, male sex, and low- and middle-income countries. The case fatality rate of ICH is high (40% at 1 month and 54% at 1 year), and only 12% to 39% of survivors can achieve long-term functional independence. Risk factors of ICH are hypertension, current smoking, excessive alcohol consumption, hypocholesterolemia, and drugs. Old age, male sex, Asian ethnicity, chronic kidney disease, cerebral amyloid angiopathy (CAA), and cerebral microbleeds (CMBs) increase the risk of ICH. Clinical presentation varies according to the size and location of hematoma, and intraventricular extension of hemorrhage. Patients with CAA-related ICH frequently have concomitant cognitive impairment. Anticoagulation related ICH is increasing recently as the elderly population who have atrial fibrillation is increasing. As non-vitamin K antagonist oral anticoagulants (NOACs) are currently replacing warfarin, management of NOAC-associated ICH has become an emerging issue.

Critical Role of the Sphingolipid Pathway in Stroke: a Review of Current Utility and Potential Therapeutic Targets

Sphingolipids are a series of cell membrane-derived lipids which act as signaling molecules and play a critical role in cell death and survival, proliferation, recognition, and migration. Sphingosine-1-phosphate acts as a key signaling molecule and regulates lymphocyte trafficking, glial cell activation, vasoconstriction, endothelial barrier function, and neuronal death pathways which plays a critical role in numerous neurological conditions. Stroke is a second leading cause of death all over the world and effective therapies are still in great demand, including ischemic stroke and hemorrhagic stroke as well as poststroke repair. Significantly, sphingolipid activities change after stroke and correlate with stroke outcome, which has promoted efforts to testify whether the sphingolipid pathway could be a novel therapeutic target in stroke. The sphingolipid metabolic pathway, the connection between the pathway and stroke, as well as therapeutic interventions to manipulate the pathway to reduce stroke-induced brain injury are discussed in this review.