Thrombolysis with Low-Dose Tissue Plasminogen Activator 3–4.5 h After Acute Ischemic Stroke in Five Hospital Groups in Japan

Direct targeting of DOCK4 by miRNA-181d in oxygen-glucose deprivation/reoxygenation-mediated neuronal injury

The miRNA-181 (miR-181) family regulates neuronal persistence during cerebral ischemia/reperfusion injury (CI/RI). Since the effect of miR-181d on CI/RI has never been studied, the current work sought to determine the involvement of miR-181d in neuronal apoptosis after brain I/R injury. To replicate in vivo and in vitro CI/RI, a transient middle cerebral artery occlusion (tMCAO) model in rats and an oxygen-glucose deficiency/reoxygenation (OGD/R) model in neuro 2A cells were developed. In both in vivo and in vitro stroke models, the expression of miR-181d was considerably higher. miR-181d suppression reduced apoptosis and oxidative stress in OGD/R-treated neuroblastoma cells, but miR-181d overexpression increased both. Furthermore, it was observed that miR-181d has a direct target in dedicator of cytokinesis 4 (DOCK4). The overexpression of DOCK4 partially overcame cell apoptosis and oxidative stress induced by miR-181d upregulation and OGD/R injury. Furthermore, the DOCK4 rs2074130 mutation was related to lower DOCK4 levels in ischemic stroke (IS) peripheral blood and higher susceptibility to IS. These findings suggest that downregulating miR-181d protects neurons from ischemic damage by targeting DOCK4, implying that the miR-181d/DOCK4 axis might be a novel therapeutic target for IS.

Effect of plasma thrombin-antithrombin complex on ischemic stroke: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Thrombin-antithrombin complex (TAT) is a prethrombotic marker, and its application in ischemic stroke is still uncertain. The purpose of this systematic review and meta-analysis is to evaluate the relationship between plasma TAT and ischemic stroke base on the current evidence.

METHODS

A systematic literature search was conducted for searching the relative studies that investigated the association of TAT and ischemic stroke in PubMed, EMBASE, and Cochrane library databases. Mean difference and 95% confidence interval as the effect sizes were synthesized by random effects model in Review Manager (RevMan) Version 5.4. The heterogeneity was investigated using the chi-square test and the possible sources of heterogeneity were explored by sensitivity analysis and meta-regression. The publication bias was estimated by Egger's tests.

RESULTS

A total of 12 eligible studies were included involving 1431 stroke cases and 532 healthy controls, of which six studies were eventually included in the meta-analysis. Plasma TAT in patients with ischemic stroke was significantly higher than that in healthy controls (MD 5.31, 95% CI = 4.12-6.51, P < 0.0001, I² = 97.8%). There is a difference of TAT level in the same period among cardioembolic, lacunar, and atherothrombotic stroke (all P < 0.0001), in which the cardioembolic stroke with the highest level. Meanwhile, it is significant of TAT levels among various phases of cardioembolic stroke and the acute phase are markedly elevated (MD 7.75, 95CI%, 6.07-9.43, P < 0.001). However, no difference was found in the atherothrombotic (P = 0.13) and lacunar stroke (P = 0.34). Besides, the higher TAT level is closely related to the poor prognosis of patients with ischemic stroke, including higher recurrence, mortality, unfavorable recovery (modified Rankin scale > 2), and poor revascularization.

CONCLUSIONS

This study suggested that plasma TAT levels are different in ischemic stroke subtypes, which are closely associated with the progression and might have an effect on the prognosis.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD: 42021248787.

Electroacupuncture attenuates ischemic injury after stroke and promotes angiogenesis via activation of EPO mediated Src and VEGF signaling pathways

Although electroacupuncture (EA) has been shown to be effective in the treatment of stroke, its mechanisms of action remain undefined. This study explored the therapeutic effects of EA in rats with cerebral ischemia-reperfusion injury (CIRI) and evaluated its possible mechanisms in promoting angiogenesis. To evaluate the effect of EA, we used 2, 3, 5-Triphenyl-2H-Tetrazolium Chloride (TTC) staining and behavior score to calculate the cerebral infarct volume and neurological deficit score after CIRI. Western blot (WB) analysis was employed to evaluate the expression of cluster of differentiation 34 (CD34), erythropoietin (EPO), vascular endothelial growth factor (VEGF) and phospho-Src (p-Src) in the brain of the rats with CIRI. On the other hand, we established an oxygen-glucose deprivation/reoxygenation (OGD/R) injury model using brain microvascular endothelial cells (BMECs), and analyzed cell viability and expression of VEGF or p-Src using cell counting kit-8 (CCK-8) and WB, respectively. Our data showed that EA at the GV26 acupoint could significantly promote the expression of CD34, EPO, VEGF and p-Src in CIRI rats. Our CCK-8 results demonstrated that intervention with recombinant EPO and VEGF proteins remarkably improved the viability of BMECs after OGD/R, while a Src inhibitor, PP1, reversed this phenotype. The WB results showed that the recombinant EPO protein increased the expression of VEGF and p-Src, which was significantly inhibited by PP1. Taken together, our findings showed that EA at the GV26 acupoint can significantly attenuate ischemic injury after stroke and promote angiogenesis via activation of EPO-mediated Src and VEGF signaling pathways. Besides, the upregulation of VEGF may also be associated with the activation of Src by EPO.

Efficacy and safety of spot heating and ultrasound irradiation on in vitro and in vivo thrombolysis models

The feasibility of transcranial sonothrombolysis has been demonstrated, although little is known about the relationships between thermal or mechanical mechanisms and thrombolytic outcomes. Therefore, the present study aims to reveal the effect and safety of temperature and ultrasound through in vitro and in vivo thrombolysis models. Artificial clots in microtubes were heated in a water bath or sonicated by ultrasound irradiation, and then clots weight decrease with rising temperature and sonication time was confirmed. In the in vitro thrombotic occlusion model, based on spot heating, clot volume was reduced and clots moved to the distal side, followed by recanalization of the occlusion. In the in vivo study, the common carotid artery of rats was exposed to a spot heater or to sonication. No brain infarct or brain blood barrier disruption was shown, but endothelial junctional dysintegrity and an inflammatory response in the carotid artery were detected. The present spot heating and ultrasound irradiation models seem to be effective for disintegrating clots in vitro, but the safety of the in vivo model was not fully supported by the data. However, the data indicates that a shorter time exposure could be less invasive than a longer exposure.

Effectiveness of Standard-Dose vs. Low-Dose Alteplase for Acute Ischemic Stroke Within 3-4.5 h

Background

The efficacy and safety of intravenous alteplase administered 3–4.5 h after acute ischemic stroke have been demonstrated. However, whether responses differ between low-dose and standard-dose alteplase during this time window and whether certain subgroups benefit more remain unknown.

Patients and Methods

The current analysis was based on a multicenter matched-cohort study conducted in Taiwan. The treatment group comprised 378 patients receiving intravenous alteplase 3–4.5 h after stroke onset, and the control group comprised 378 age- and sex-matched patients who did not receive alteplase treatment during the same period. Standard- and low-dose alteplase was administered to patients at the physician's discretion.

Results

Overall, patients receiving alteplase exhibited more favorable outcomes than did controls [34.0 vs. 22.7%; odds ratio (OR): 1.75, 95% confidence interval (CI): 1.27–1.42], and the effectiveness was consistent in all subgroups. Although patients in the standard-dose group (n = 182) were younger than those in the low-dose (n = 192) group, the proportions of patients with favorable outcomes (36.3 vs. 31.8%; OR: 1.22, 95% CI: 0.80–1.88) and symptomatic hemorrhage (2.8 vs 4.2%; OR: 0.65, 95% CI: 0.21–2.02) were consistently comparable in a covariate-adjusted model and an age-matched cohort. In the subgroup analysis, patients with cardioembolism, atrial fibrillation, and hypercholesterolemia were more likely to achieve favorable outcomes after receiving standard-dose than low-dose alteplase.

Conclusion

In the 3–4.5 h time window, the effectiveness and safety of standard-dose and low-dose alteplase may be comparable. A standard dose may be selected for patients with cardioembolism, atrial fibrillation, or hypercholesterolemia.

Association Between Oral Anticoagulants and Stroke Severity at Onset in Elderly Patients with Cardioembolic Stroke Due to Non-Valvular Atrial Fibrillation

OBJECTIVES

This study aimed to determine whether oral anticoagulant therapy affects the severity of cerebral infarction at onset in elderly patients with non-valvular atrial fibrillation.

MATERIALS AND METHODS

This retrospective study included 330 elderly patients (aged ≥75 years) who were hospitalized for cardioembolic stroke due to non-valvular atrial fibrillation. Patients' medical history, stroke severity at onset (National Institutes of Health Stroke Scale score), and the prevalence of large vessel occlusion were compared between patients who received oral anticoagulant therapy (n = 109) and those who did not receive oral anticoagulant therapy (n = 221).

RESULTS

Stroke severity was significantly lower in patients who received anticoagulants than in those who did not receive anticoagulants (6 versus 12; P = 0.021). Patients who did not receive anticoagulants had a significantly higher prevalence of large vessel occlusion (52% versus 37%; P = 0.010). After resampling based on propensity score matching, both median stroke severity (7 versus 12; P = 0.046) and large vessel occlusion prevalence (36% versus 57%; P = 0.019) were significantly lower in patients who received anticoagulant therapy.

CONCLUSIONS

The results of this study suggest that elderly patients with non-valvular atrial fibrillation who are administered oral anticoagulant therapy before the onset of cerebral infarction develop less severe stroke than those who are not receiving oral anticoagulant therapy. Thus, oral anticoagulant therapy should be actively considered in patients with non-valvular atrial fibrillation as it does not only prevents cerebral embolism, but also reduces the risk of severe sequelae.

microRNA-186 alleviates oxygen-glucose deprivation/reoxygenation-induced injury by directly targeting hypoxia-inducible factor-1α

Previous studies have suggested that microRNA-186 (miR-186) can be induced under hypoxic conditions, and is associated with apoptosis. This study was undertaken to explore the exact role of this microRNA (miRNA) in the apoptotic death of neurons during cerebral ischemic/reperfusion (I/R) injury. To model cerebral ischemia/reperfusion (I/R) injuries, we utilized a transient middle cerebral artery occlusion approach in rats, as well as a model of oxygen-glucose deprivation/reoxygenation (OGD/R) in Neuro2a cells. We found that in both in vitro and in vivo models of cerebral I/R injuries, levels of miR-186 were markedly decreased. When we overexpressed miR-186, this was associated with a reduction in the apoptotic death of neuroblastoma cells in the OGD/R model system, whereas the opposite was true when this miRNA was instead inhibited. We further found miR-186 to directly target hypoxia-inducible factor 1α (HIF-1α) by interacting with the 3'-untranslated region of this mRNA. When we knocked down HIF-1α, this partially overcame the apoptotic death of cells in response to OGD/R injury and associated miR-186 downregulation. Our findings indicate that miR-186 is able to reduce ischemic injury to neurons at least in part through downregulating HIF-1α, suggesting that the miR-186/HIF-1α axis is a potential therapeutic target for the treatment of ischemic stroke.

Mechanisms and repair strategies for white matter degeneration in CNS injury and diseases

White matter degeneration is an important pathophysiological event of the central nervous system that is collectively characterized by demyelination, oligodendrocyte loss, axonal degeneration and parenchymal changes that can result in sensory, motor, autonomic and cognitive impairments. White matter degeneration can occur due to a variety of causes including trauma, neurotoxic exposure, insufficient blood flow, neuroinflammation, and developmental and inherited neuropathies. Regardless of the etiology, the degeneration processes share similar pathologic features. In recent years, a plethora of cellular and molecular mechanisms have been identified for axon and oligodendrocyte degeneration including oxidative damage, calcium overload, neuroinflammatory events, activation of proteases, depletion of adenosine triphosphate and energy supply. Extensive efforts have been also made to develop neuroprotective and neuroregenerative approaches for white matter repair. However, less progress has been achieved in this area mainly due to the complexity and multifactorial nature of the degeneration processes. Here, we will provide a timely review on the current understanding of the cellular and molecular mechanisms of white matter degeneration and will also discuss recent pharmacological and cellular therapeutic approaches for white matter protection as well as axonal regeneration, oligodendrogenesis and remyelination.

Individualized intravenous thrombolytic strategy for acute ischemic stroke with large vessel occlusion on the era of mechanical thrombectomy: cases report

Intravenous thrombolysis for acute ischemic stroke within 4.5 h after the onset of symptoms has become a standard therapy that is recommended by many trials and clinical guidelines. As on the era of mechanical thrombectomy for acute ischemic stroke with large vessel occlusions, whether intravenous thrombolysis (IVT) is still necessary, and how to choose the optimal dose are still controversy. Here, we reported two cases of acute ischemic stroke with large vessel occlusions that both achieved complete recanalization after IVT. Then, IVT was terminated in advance, and dynamic surveillance by DSA was performed to achieve individual treatment. However, both of the cases presented with hemorrhagic transformation. We analyzed the probable reasons and put forward thoughts from ourselves.

Intravenous Thrombolysis Administration 3-4.5 h After Acute Ischemic Stroke: A Retrospective, Multicenter Study

Background and Objectives: Intravenous recombinant tissue plasminogen activator (rt-PA) has been approved for acute ischemic stroke (AIS) within 3 h after onset and the treatment was then extended to 4.5 h. However, the Food and Drug Administration did not approve the indication in the expanded time window. This retrospective, matched cohort study aims to investigate the effectiveness and safety of rt-PA in AIS at 3-4.5 h after onset. Materials and Methods: The treatment group included AIS patients receiving rt-PA at 3-4.5 h after onset, otherwise complying with the regulation, in the stroke registries in 16 hospitals between 2008 and 2017. The control group included age- and sex-matched patients not receiving intravenous thrombolysis from the same registries, excluding those with contraindications. The primary outcome was modified Rankin Scale (mRS) 0-1 at day 90. The safety outcomes were any intracerebral hemorrhage (ICH), early neurological deterioration and 3-month mortality. Results: Each group had 374 patients. There were 34.0% of patients with 3-month mRS 0-1 in the treatment group vs. 22.7% in the control group with an odds ratio of 1.75 (95% confidence intervals, 1.27 to 2.42, P = 0.001). There was no difference in symptomatic ICH, early neurological deterioration and 3-month mortality rates between two groups. The 3-month mRS and symptomatic ICH did not differ significantly in patients receiving standard dose or low dose of rt-PA. Conclusions: Our results support the prescription of rt-PA in AIS patients 3-4.5 h after onset as an effective and tolerable treatment in their functional recovery.

[Recombinant tissue plasminogen activator therapy for acute ischemic stroke in older patients]

AIM

As the number of aged stroke patients increases in Japan, the proportion of older patients who receive recombinant tissue plasminogen activator (rt-PA, 0.6 mg/kg) is also rising. However, the Japanese stroke guideline indicates that rt-PA therapy must be administered very carefully in older patients (i.e. ≥81 years of age) because of serious complications after the therapy. We retrospectively assessed the clinical outcomes of rt-PA therapy in older patients.

METHODS

This study included 321 patients who received rt-PA therapy for acute cerebral infarction at our hospital between April 2007 and April 2017. The outcomes (modified Rankin Scale [mRS] score at 3 months after treatment) and symptomatic intracerebral hemorrhaging (sICH) were compared and analyzed between patients ≥81 years of age (group A) and those <81 years of age (group B). In addition, propensity score matching was performed for the factors shown to have significant differences by a univariate analysis in order to adjust for confounding factors, and the outcomes were compared.

RESULTS

There were 58 patients in group A (18.1%) and 263 patients in group B (81.9%). The rate of favorable outcomes (mRS 0-1) was lower in group A (12.1%) than in group B (44.1%) (P<0.01). The mortality rate was higher in group A (17.2%) than in group B (4.6%) (P=0.002). No marked differences were observed between the 2 groups regarding the rate of sICH (group A, 3.4%; group B, 3.0%; P=1.00). After propensity score matching, the proportion of patients with favorable outcomes was significantly lower in group A (13.2%) than in group B (36.8%) (P=0.032). There were no marked differences in the mortality rates between the groups (group A, 17.2%; group B, 4.6%) (P=0.200), and no patients in either group had sICH.

CONCLUSION

No marked differences in the incidence of ICH were observed between the older and younger groups receiving intravenous rt-PA therapy. However, in terms of efficacy, the proportion of patients with favorable outcomes was significantly lower in the older group than in the younger group.

Safety and Efficacy of Intravenous Low-Dose Alteplase in Relative Contraindication Patients with Acute Ischemic Stroke

OBJECT

The purpose of this study was to investigate the safety and efficacy of intravenous low-dose alteplase for acute ischemic stroke patients with relative contraindications.

METHODS

The consecutive series of patients admitted within 4.5 hours of ischemic stroke onset between September 2012 and April 2017 were retrospectively evaluated. A good outcome at 90 days and symptomatic intracerebral hemorrhage were evaluated to determine the association with intravenous low-dose alteplase, especially in the presence of relative contraindications.

RESULTS

Intravenous low-dose alteplase was administered to 219 of 315 patients (70%). A significantly higher number of patients treated with intravenous low-dose alteplase achieved a good outcome compared with those treated without alteplase (60% versus 44%; P = .014). The incidence of symptomatic intracerebral hemorrhage was not significantly different between the treatment groups. Multivariable logistic regression analysis of good outcome revealed that the significant independent factors were age of 81 years or older (odds ratio, .33; 95% confidence interval, .18-.60), National Institutes of Health Stroke Scale (NIHSS) of 4 or less (compared with NIHSS, 5-25; odds ratio, 3.3; 95% confidence interval, 1.8-6.4), modified Rankin scale score of 1 before stroke (odds ratio, .32; 95% confidence interval, .14-.73), and large changes on first brain imaging (odds ratio, .16; 95% confidence interval, .058-.44). Even with these relative contraindications, intravenous low-dose alteplase was still associated with good outcome (odds ratio, 3.1; 95% confidence interval, 1.6-5.8).

CONCLUSIONS

Intravenous low-dose alteplase treatment can be safe and effective in relative contraindication patients with acute ischemic stroke.

Molecular Mechanisms of Oligodendrocyte Regeneration in White Matter-Related Diseases

Even in adult brains, restorative mechanisms are still retained to maintain the microenvironment. Under the pathological conditions of central nervous system (CNS) diseases, several immature cells in the brain would be activated as a compensative response. As the concept of the neurovascular unit emphasizes, cell-cell interactions play important roles in this restorative process. White matter damage and oligodendrocyte loss are representative characteristics for many neurodegenerative diseases. In response to oligodendrocyte damage, residual oligodendrocyte precursor cells (OPCs) initiate their proliferation and differentiation for the purpose of remyelination. Although mechanisms of oligodendrogenesis and remyelination in CNS diseases are still mostly unknown and understudied, accumulated evidence now suggests that support from neighboring cells is necessary for OPC proliferation and differentiation. In this review, we first overview basic mechanisms of interaction between oligodendrocyte lineage cells and neighboring cells, and then introduce how oligodendrogenesis occurs under the conditions of neurodegenerative diseases, focusing on vascular cognitive impairment syndrome, Alzheimer’s disease, and multiple sclerosis.

Protective effects of a radical scavenger edaravone on oligodendrocyte precursor cells against oxidative stress

Oligodendrocyte precursor cells (OPCs) play critical roles in maintaining the number of oligodendrocytes in white matter. Previously, we have shown that oxidative stress dampens oligodendrocyte regeneration after white matter damage, while a clinically proven radical scavenger, edaravone, supports oligodendrocyte repopulation. However, it is not known how edaravone exerts this beneficial effect against oxidative stress. Using in vivo and in vitro experiments, we have examined whether edaravone exhibits direct OPC-protective effects. For in vivo experiments, prolonged cerebral hypoperfusion was induced by bilateral common carotid artery stenosis in mice. OPC damage was observed on day 14 after the onset of cerebral hypoperfusion, and edaravone was demonstrated to decrease OPC death in cerebral white matter. In vitro experiments also confirmed that edaravone reduced oxidative-stress-induced OPC death. Because white matter damage is a major hallmark of many neurological diseases, and OPCs are instrumental in white matter repair after injury, our current study supports the idea that radical scavengers may provide a potential therapeutic approach for white matter related diseases.

Clinical Study of Intravenous, Low-Dose Recombinant Tissue Plasminogen Activator for Acute Cerebral Infarction: Comparison of Treatment within 3 Hours versus 3-4.5 Hours

BACKGROUND

An intravenous recombinant tissue plasminogen activator (rt-PA, alteplase .6 mg/kg) for acute cerebral infarction within 3 hours of onset was approved in Japan in 2005. The treatment window was subsequently extended to within 4.5 hours of onset. However, few Japanese studies have compared the efficacy and safety of rt-PA therapy between patients treated within 3 hours and patients treated within 3-4.5 hours.

METHODS

This study included 323 patients who received rt-PA for acute cerebral infarction within 3 hours or 3-4.5 hours between April 2007 and March 2017. Patients' characteristics, outcomes (modified Rankin Scale [mRS] score at 3 months), and symptomatic intracranial hemorrhage (sICH) were retrospectively investigated.

RESULTS

Of the 323 patients, 219 were treated within 3 hours and 104 were treated at 3-4.5 hours. Among patients receiving rt-PA alone, 154 were treated within 3 hours (3-hour group), and 69 were treated at 3-4.5 hours (3-4.5-hour group). There was no difference in the sICH rate (3.9% versus 4.3%, respectively; P = 1.00) or mRS score of 0-1 (38.3% versus 40.6%, respectively; P = .76) between these groups. In patients receiving additional neuroendovascular therapy, 65 were in the 3-hour group and 35 were in the 3-4.5-hour group. There was no significant difference in the sICH rate (1.5% versus 0%, respectively; P = 1.00) or mRS score of 0-1 (30.8% versus 31.4%, respectively; P = 1.00) between these groups.

CONCLUSIONS

Low-dose rt-PA treatment from either 3 or 3-4.5 hours after acute cerebral infarction has the same efficacy and safety.

Potential Therapeutic Mechanisms and Tracking of Transplanted Stem Cells: Implications for Stroke Treatment

Stem cell therapy is a promising potential therapeutic strategy to treat cerebral ischemia in preclinical and clinical trials. Currently proposed treatments for stroke employing stem cells include the replacement of lost neurons and integration into the existing host circuitry, the release of growth factors to support and promote endogenous repair processes, and the secretion of extracellular vesicles containing proteins, noncoding RNA, or DNA to regulate gene expression in recipient cells and achieve immunomodulation. Progress has been made to elucidate the precise mechanisms underlying stem cell therapy and the homing, migration, distribution, and differentiation of transplanted stem cells in vivo using various imaging modalities. Noninvasive and safe tracer agents with high sensitivity and image resolution must be combined with long-term monitoring using imaging technology to determine the optimal therapy for stroke in terms of administration route, dosage, and timing. This review discusses potential therapeutic mechanisms of stem cell transplantation for the treatment of stroke and the limitations of current therapies. Methods to label transplanted cells and existing imaging systems for stem cell labeling and in vivo tracking will also be discussed.

The Chinese Stroke Association scientific statement: intravenous thrombolysis in acute ischaemic stroke

The most effective medical treatment for acute ischaemic stroke (AIS) is to offer intravenous thrombolysis during the ultra-early period of time after the onset. Even based on the Consensus of Chinese Experts on Intravenous Thrombolysis for AIS in 2012 and 2014 Chinese Guidelines on the Diagnosis and Treatment of AIS, the rate of thrombolysis for AIS in China remained around 2.4%, and the rate of intravenous tissue plasminogen activator usage was only about 1.6% in real world. The indication of thrombolysis for AIS has been expanded, and contraindications have been reduced with recently published studies. In order to facilitate the standardisation of treating AIS, improve the rate of thrombolysis and benefit patients who had a stroke, Chinese Stroke Association has organised and developed this scientific statement.

Treatment of Cervical Artery Dissection: Antithrombotics, Thrombolysis, and Endovascular Therapy

Cervical artery dissection (CAD) is an important cause of stroke for young patients, accounting for 5–22% of strokes in patients <45 years of age, which presents not only a great burden to the stroke victims but also a financial burden to the family and society. Because CAD can lead to different clinical lesions, including neuropathy, acute ischemic stroke, and subarachnoid hemorrhage, and is an arterial dissection with a self-healing tendency, the treatment options depend on the clinical manifestations. The main purpose of the treatment is to control CAD-induced neuronal damage and to restore blood flow. The treatment programs include drug treatment and endovascular treatment. However, antithrombotic treatment is crucial. Both antiplatelet drugs and anticoagulant drugs are used to reduce the risk of stroke, but whether one treatment strategy is more effective than the other is unknown. The efficacy and timing of the endovascular treatment of CAD remain controversial.

In Vivo Bioimpedance Spectroscopy Characterization of Healthy, Hemorrhagic and Ischemic Rabbit Brain within 10 Hz-1 MHz

Acute stroke is a serious cerebrovascular disease and has been the second leading cause of death worldwide. Conventional diagnostic modalities for stroke, such as CT and MRI, may not be available in emergency settings. Hence, it is imperative to develop a portable tool to diagnose stroke in a timely manner. Since there are differences in impedance spectra between normal, hemorrhagic and ischemic brain tissues, multi-frequency electrical impedance tomography (MFEIT) shows great promise in detecting stroke. Measuring the impedance spectra of healthy, hemorrhagic and ischemic brain in vivo is crucial to the success of MFEIT. To our knowledge, no research has established hemorrhagic and ischemic brain models in the same animal and comprehensively measured the in vivo impedance spectra of healthy, hemorrhagic and ischemic brain within 10 Hz–1 MHz. In this study, the intracerebral hemorrhage and ischemic models were established in rabbits, and then the impedance spectra of healthy, hemorrhagic and ischemic brain were measured in vivo and compared. The results demonstrated that the impedance spectra differed significantly between healthy and stroke-affected brain (i.e., hemorrhagic or ischemic brain). Moreover, the rate of change in brain impedance following hemorrhagic and ischemic stroke with regard to frequency was distinct. These findings further validate the feasibility of using MFEIT to detect stroke and differentiate stroke types, and provide data supporting for future research.

A free radical scavenger edaravone suppresses systemic inflammatory responses in a rat transient focal ischemia model

A free radical scavenger edaravone is clinically used in Japan for acute stroke, and several basic researches have carefully examined the mechanisms of edaravone's protective effects. However, its actions on pro-inflammatory responses under stroke are still understudied. In this study, we subjected adult male Sprague-Dawley rats to 90-min middle cerebral artery (MCA) occlusion followed by reperfusion. Edaravone was treated twice via tail vein; after MCA occlusion and after reperfusion. As expected, edaravone-treated group showed less infarct volume and edema formation compared with control group at 24-h after an ischemic onset. Furthermore, edaravone reduced the levels of plasma interleukin (IL)-1β and matrix metalloproteinase-9 at 3-h after ischemic onset. Several molecules besides IL-1β and MMP-9 are involved in inflammatory responses under stroke conditions. Therefore, we also examined whether edaravone treatment could decrease a wide range of pro-inflammatory cytokines/chemokines by testing rat plasma samples with a rat cytokine array. MCAO rats showed elevations in plasma levels of CINC-1, Fractalkine, IL-1α, IL-1ra, IL-6, IL-10, IP-10, MIG, MIP-1α, and MIP-3α, and all these increases were reduced by edaravone treatment. These data suggest that free radical scavengers may reduce systemic inflammatory responses under acute stroke conditions, and therefore, oxidative stress can be still a viable target for acute stroke therapy.