Tony Wang

Activation of Akt/GSK-3beta/beta-catenin signaling pathway is involved in survival of neurons after traumatic brain injury in rats

Abstract Objective: Apoptotic cell death is an important factor influencing the prognosis after traumatic brain injury (TBI). Akt/GSK-3beta/beta-catenin signaling plays a critical role in the apoptosis of neurons in several models of neurodegeneration. The goal of this study was to determine if the mechanism of cell survival mediated by the Akt/GSK-3beta/beta-catenin pathway is involved in a rat model of TBI. Methods: TBI was performed by a controlled cortical impact device. Expression of Akt, phospho-Akt, GSK-3beta, phospho-GSK-3beta, beta-catenin, phospho-beta-catenin were examined by immunohistochemistry and Western blot analysis. Double immunofluorenscent staining was used to observe the neuronal expression of the aforementioned subtrates. Terminal deoxynucleotidyl transferase-mediated uridine 5’-triphosphate-biotin nick end-labeling (TUNEL) staining was performed to identify apoptosis. Results: Western blot analysis showed that phospho-Akt significantly increased at 4 hours post-TBI, but decreased after 72 hours post-TBI. Phospho-GSK-3beta – phosphorylated by phospho-Akt – slightly increased at 4 hours post-TBI and peaked at 72 hours post-TBI. These changes in Phospho-GSK-3beta expression were accompanied by a marked increase in expression of phospho-beta-catenin at 4 hours post-TBI which was sustained until 7 days post-TBI. Double staining of phospho-Akt and NeuN revealed the colocalization of phospho-Akt positive cells and neuronal cells. In addition, double staining of phospho-Akt and TUNEL showed no colocalization of phospho-Akt cells and TUNEL-positive cells. Conclusion: Phosphorylation of Akt (Ser473) and GSK3beta (Ser9) was accelerated in the injured cortex, and involved in the neuronal survival after TBI. Moreover, neuroprotection of beta-catenin against ischemia was partly mediated by enhanced and persistent activation of the Akt/GSK3beta signaling pathway.

Effect of remote ischemic postconditioning on an intracerebral hemorrhage stroke model in rats

Abstract Background and purpose: While recent studies suggest that remote ischemic postconditioning (RIP) therapy may be of benefit to patients with acute ischemic stroke, RIP’s effects on intracerebral hemorrhage (ICH) still remains unclear. In the present study, the use of RIP in a rat model ICH was investigated to elucidate any potential beneficial or detrimental effects as determined by motor testing, blood brain barrier integrity, and brain water content, as well as aquaporin-4 (AQP-4) and matrix metalloproteinase-9 (MMP-9) expression. Methods: ICH was induced in Sprague–Dawley rats and they were randomized into either a control (n = 24) or RIP treatment (n = 24) group. RIP was performed by repetitive, brief occlusion and release of the bilateral femoral arteries. Functional outcome in each group was assessed by neurologic deficits on vibrissae-elicited forelimb placing test and a 12-point outcome scale. At 72 hours, brain blood volume, water content, blood–brain barrier (BBB) permeability, and protein expression of AQP-4 and MMP-9 were determined. Results: This collagenase model yielded well-defined striatal hematomas. Vibrissae-elicited forelimb placement was significantly (P<0·01) affected by ICH. However, there was no significant difference between the RIP and control groups at either 24 or 72 hours. A 12-point neurological deficit score also failed to differentiate between the RIP and control. There were no significant differences between the two groups in cerebral blood volumes, brain water content, Evans blue extravasations, and expressions of AQP-4 and MMP-9. Conclusions: Although RIP did not show a beneficial effect in our ICH model, treatment with RIP did not exacerbate ICH.

Reduction of brain edema and expression of aquaporins with acute ethanol treatment after traumatic brain injury

OBJECT Previous studies have demonstrated that traumatic brain injury (TBI) causes brain edema by allowing excessive water passage through aquaporin (AQP) proteins. To establish the potential neuroprotective properties of ethanol as a post-TBI therapy, in the present study the authors determined the effect of ethanol on brain edema, AQP expression, and functional outcomes in a post-TBI setting. METHODS Adult male Sprague-Dawley rats weighing between 425 and 475 g received a closed head TBI in which Maramarous impact-acceleration method was used. Animals were given a subsequent intraperitoneal injection of 0.5 g/kg or 1.5 g/kg ethanol at 60 minutes post-TBI and were killed 24 hours after TBI. Brains were subsequently examined for edema along with AQP mRNA and protein expression. Additional animals treated with either 0.5 g/kg or 1.5 g/kg ethanol at 60 minutes post-TBI were designated for cognitive and motor testing for 3 weeks. RESULTS Ethanol administration post-TBI led to significantly (p < 0.05) lower levels of brain edema as measured by brain water content. This downregulation in brain edema was associated with significantly (p < 0.05) reduced levels of AQP mRNA and protein expression as compared with TBI without treatment. These findings concur with cognitive studies in which ethanol-treated animals exhibited significantly (p < 0.05) faster radial maze completion times. Motor behavioral testing additionally demonstrated significant (p < 0.05) beneficial effects of ethanol, with treated animals displaying improved motor coordination when compared with untreated animals. CONCLUSIONS The present findings suggest that acute ethanol administration after a TBI decreases AQP expression, which may lead to reduced cerebral edema. Ethanol-treated animals additionally showed improved cognitive and motor outcomes compared with untreated animals.

Diazoxide and cyclosporin A protect primary cholinergic neurons against beta-amyloid (1-42)-induced cytotoxicity

Abstract Objective: Activation of mitochondrial (MitoKATP) channels was found to protect against anoxic and chemical stress in brain. This present study sought to investigate the ability of diazoxide and cyclosporin A to antagonize cytotoxicity induced by beta-amyloid peptide (A-beta1-42) in cultured rat primary basal forebrain cholinergic neurons. Methods: Cytotoxicity was induced by A-beta1-42 (2 μM) in the presence of either diazoxide (500 μM), a selective opener of the mitochondrial ATP-sensitive potassium channel (MitoKATP), or cyclosporin A (20 μM), an inhibitor of the mitochondrial permeability transition pore (MTP), or the combination of both the reagents. We determined cell morphology and cell viability using MTT assay and expression levels of anti-apoptotic protein (Bcl-2), pro-apoptotic proteins (Bax, cytochrome C, caspase-3 and cleaved caspase-3) using Western blotting at 24 hours and 72 hours. Results: Cell viability decreased markedly after exposure to A-beta1-42 for 72 hours with a decrease in the expression of Bcl-2 protein and cytochrome C and an increase in the caspase-3 and cleaved caspase-3 levels. Both diazoxide and cyclosporin A exerted significant protective effects on cell viability by ameliorating the decrease in Bcl-2 and the increase in cytochrome c and caspase-3 activity induced by A-beta1-42. The combination of both the reagents had a greater protective effect than either one alone. Conclusions: The present research demonstrates that activation of MitoKATP channels independently or in combination with inhibitors of the MTP can elicit a protective effect against primary cholinergic neuron cytotoxicity induced by A-beta1-42. These findings suggest new mitochondrial targets for the development of therapeutic agents against A-beta-induced cytotoxicity.

The relationship of asymptomatic intracranial artery stenosis and Framingham stroke risk profile in a Northern Chinese industrial city

Abstract Background: Intracranial artery stenosis may be the most frequent cause of ischemic stroke in the world. Early detection of asymptomatic intracranial artery stenosis may allow for therapeutic intervention. Most elements of the Framingham stroke risk profile (FSRP) are also risk factors for intracranial artery stenosis. Thus, the FSRP might play a role in detecting asymptomatic intracranial artery stenosis. Objective: To investigate the relationship between the FSRP and asymptomatic intracranial artery stenosis. Methods: A sample of 5852 subjects (age >40 years) was selected from the KaiLuan study. All participants received transcranial Doppler ultrasound examinations to detect the presence and quantify the severity of intracranial arterial stenosis. Demographic and clinical variables were investigated at the time of examination. Binary logistic regression analyses was performed to determine the odds ratio of FSRP components to asymptomatic intracranial stenosis before and after adjusted for gender, body mass index (BMI), and total cholesterol (TC). Results: The subjects with intracranial artery stenosis were older than those without (68·2 versus 64·9), and the systolic blood pressure was higher in those with intracranial artery stenosis (146·86 versus 136·39). Among intracranial artery stenosis subjects, 77·5% had hypertension, 26·1% had diabetes, 8·9% had left ventricular hypertrophy, and 4·8% had atrial fibrillation. Logistic regression analyses revealed that age, systolic blood pressure, diabetes, atrial fibrillation, and left ventricular hypertrophy were risk factors for intracranial artery stenosis. The incidence of asymptomatic intracranial artery stenosis correlated with increasing FSRP scores. The odds ratios of intracranial artery stenosis from the lowest to the highest FSRP quartiles were as follows: 1 (reference group), 1·77 (95% CI: 1·23–2·56), 2·84 (95% CI: 2·02–3·98), 5·65 (95% CI: 4·03–7·93). Conclusion: FSRP plays an important role in detecting asymptomatic intracranial artery stenosis.

A New Thrombosis Model of the Superior Sagittal Sinus Involving Cortical Veins

OBJECTIVE Patients with cerebral sinus and cortical venous thrombosis develop venous infarcts in approximately 50% of cases, resulting in serious clinical symptoms. An animal model is needed to further clarify the underlying mechanisms and consequences surrounding cerebral venous sinus thrombosis, particularly for severe ones. METHODS Adult male Sprague-Dawley rats were used to develop a new superior sagittal sinus thrombosis model involving cortical veins. The superior sagittal sinus was exposed and ligated. A microcatheter was inserted into the sinus, then both common carotid arteries were temporary occluded to reduce cerebral blood flow, and thrombin was injected into the sinus. Twenty-four hours later, after evaluating neurological function and obtaining a magnetic resonance imaging, animals were sacrificed and data pertaining to brain water content, infarct volume, and tissue histology was collected. RESULTS Superior sagittal sinus thrombosis and brain infarction were detected in all rats (100%). Hemorrhagic infarction, when present, and brain edema were observed in the brain parenchyma of the parietal lobe. The rate of hemorrhage was 59%, which is similar to that seen clinically in patients with superior sagittal sinus thrombosis. Brain edema, as measured by brain water content percentage, was significantly increased in thrombosed animals compared with sham-operated animals (80.8% ± 0.55% vs. 78.8% ± 0.14%, P < 0.05). Infarct volumes were 53.02 ± 7.91 mm(3). CONCLUSIONS We suggest that our modified model of superior sagittal sinus thrombosis, involving cortical veins, is suitable for the study of its underlying mechanisms, as well as therapeutic approaches directed at the disease.

Frequency and etiological diagnosis of ischemic stroke in Chinese young adults.

Abstract Cerebrovascular disease is the second commonest cause of death, and over a third of stroke deaths occur in developing countries. To fulfil the current gap on data, this systematic review is focused on the epidemiology of stroke, stroke subtypes, risk factors, etiological diagnosis, the status of treatment and mortality of young adults’ ischemic stroke in China.

Association of plaque compositions and stenosis patterns in carotid bifurcation using MR imaging

Abstract Objectives: To investigate the relationship between plaque compositions and stenosis patterns in patients with atherosclerotic plaques at the carotid bifurcation using magnetic resonance (MR) imaging. Methods: One hundred and four carotid arteries with stenosis over 50% from 75 symptomatic stroke patients (64 male and 11 female; mean age 58·2±13·3 years) were studied. Plaque compositions were analyzed by high-resolution MR imaging using a 3·0T MR with a surface coil. Stenosis patterns were classified into three types according to contrast-enhanced MR angiography images. Correlations of different components of plaques and stenosis patterns were analyzed. Results: One hundred and four carotid arteries were analyzed. Three stenosis patterns were identified. The prevalences of the three patterns are as follows: type I (total occlusion) at 27·9% (29/104), type II (local plaque with normal distant flow) at 56·7% (59/104), and type III (local plaque with impaired distant flow) at 15·4% (16/104). The contingency coefficients between stenosis pattern and stability, intraplaque hemorrhage (IPH), lipid necrotic core (LNC), and ulcer were 0·383 (P = 0·000), 0·290 (P = 0·008), 0·439 (P = 0·000), and 0·388 (P = 0·000), respectively. Multinomial analysis showed that compared with type III vessels, type I vessels were more likely to contain IPH (P = 0·019) and less likely to contain large LNC (P = 0·001); type II vessels had a greater possibility for containing IPH than type III vessels (P = 0·009); LNC was more likely to be found in type II than in type I vessels (P = 0·000). No significant difference was found in ulceration prevalence between type II and type III vessels (P = 0·058). Conclusions: The current study demonstrated positive associations between stenosis patterns and plaque compositions.

Furthering our understanding of stroke and other neurological pathologies

Recently published data from the Centers for Disease Control (CDC) indicated that cerebrovascular disease was the fourth leading cause of death. This fact reminds us that diseases of the nervous system continue to pose both a diagnostic as well as treatment challenge. As such, further research is warranted in order to shed light on the latest understanding in the diagnosis and pathophysiology of neurological disease. In an attempt to increase our focus on the research, we have selected 12 representative articles among numerous submissions for discussion at the Tiantan International Stroke Conference in 2012, one of the largest stroke conferences in the world. This current special issue of Neurological Research will primarily deal with cerebrovascular disease, especially stroke. Another prominent neurologic disease, amytrophic lateral sclerosis (ALS) will be featured along with additional articles concerning traumatic brain injury (TBI) and neuropathic pain. As more and more research is conducted in cerebrovascular disease, more attention is being directed to systems seemingly outside of the realm of the nervous system. This notion is echoed by a featured article in which the authors advocate a more comprehensive approach. Research should no longer primarily focus on the neuron, but be directed towards the neurovascular unit, which also encompasses glial and vascular elements. Understanding the complex interplay between the three will be critical in identifying potential therapeutic avenues for cerebrovascular disease. Although looking ‘outside’ the nervous system is an important step in better understanding the mechanisms behind neuroprotection, other authors are advocating looking outside the ischemic penumbra for clues towards neuroprotection in a post-stroke setting. Past research in stroke has primarily focused on possible therapies within the ischemic penumbra. This issue of Neurological Research features an article in which the authors assert that attention should be shifted to possible remedies directed beyond the ischemic penumbra. Reasons for this are twofold. First, damage within the ischemic penumbra often occurs so rapidly that any attempts for treatment often prove futile. Second, there is increasing evidence that stroke induces numerous cellular and hemodynamic changes outside the region of ischemia. As such, the pathophysiological cascades that occur in nonischemic brain tissue warrant further investigation as it could hold the key to post-stroke neuroprotection. The current issue highlights many novel notions of stroke pathophysiology, knowledge of which could spur future treatment. NADPH oxidase (NOX) was originally identified in neutrophils as serving a critical role in the immune system as an antibacterial. Recent research has elucidated that while NOX may play a beneficial role in the immune system that it may be deleterious in stroke. In fact, the same properties — the ability to generate free radicals — that make NOX such an effective antimicrobial, appear also to cause damage in a stroke setting. The superoxide generated by NOX is thought to contribute to blood– brain barrier disruption, edema formation along with secondary hemorrhage. NOX is thought to mediate most of its damage in the post-stroke period in which blood flow, and thus, oxygenation is re-established. The reintroduced oxygen thus serves as a substrate for NOX, which leads to superoxide production and the aforementioned sequelae. Subsequently, blocking NOX, especially in the re-oxygenation phase, could attenuate many of the negative outcomes seen in stroke. While carotid artery atherosclerosis remains a major causative agent in stroke, such a condition typically affects an older population. Little in the existing literature addresses risk factors in younger stroke victims. Although most do not view stroke in the young as a pressing issue, this is not the case in China. An estimated 10% of stroke cases in China are in those aged 18–45 years and with some epidemiological studies indicating stroke as the leading cause of death in China, stroke in the young thus represents a significant if not overlooked issue. This current issue reveals several potential risk factors for stroke unique to a younger population such as pregnancy as well as oral contraceptive use. The authors also identified patent foramen ovale and hereditary