The neurotoxicity of LA on neuro a comparative lidocaine, bupivacaine, mepivacaine, and ropivacaine

合集下载

脑梗死神经元特异性烯醇化酶的变化及其临床意义

脑梗死神经元特异性烯醇化酶的变化及其临床意义唐江伟【摘要】神经元特异性烯醇化酶(NSE)大量存在于脑组织神经元细胞和神经内分泌细胞中,脑梗死时脑组织受损,NSE由神经元细胞中漏出进入脑脊液和血液,由于其在正常情况下外周血中仅有微量,因此脑脊液和血液中NSE水平可作为脑组织中神经元坏死的客观指标,判断脑梗死面积大小、评价治疗效果和估测预后的手段.现就国内外相关研究加以综述.【期刊名称】《中国现代药物应用》【年(卷),期】2012(006)013【总页数】2页(P22-23)【关键词】神经元特异性烯醇化酶;脑梗死【作者】唐江伟【作者单位】300240,天津市第四中心医院神经内科【正文语种】中文脑梗死具有高发病率、高致残率、高死亡率的特点，不仅威胁到个人的生活质量，同时给社会和家庭也带来巨大的负担，因此目前对脑梗死的早期诊断、早期治疗成为神经科研究的热点。

急性脑梗死的主要病理变化是神经元坏死及神经髓鞘崩解，为缺血缺氧性脑损伤所导致。

近年来多项研究表明脑脊液和血液中神经元特异性烯醇化酶浓度变化与脑组织中损伤明显相关，因此研究NSE在外周血中含量变化有着重要的临床意义。

现就脑梗死后NSE的变化规律及其临床意义加以总结。

烯醇化酶广泛分布于人体各种组织细胞中，是在细胞能量代谢过程中参与糖酵解途径的关键酶。

其主要作用是催化糖代谢过程中的2-磷酸甘油酸转变成2-磷酸烯醇式丙酮酸，而2-磷酸烯醇式丙酮酸可在丙酮酸激酶的作用下生成丙酮酸，与还原型辅酶、乳酸脱氢酶作用生成乳酸。

现在可以知道烯醇化酶有5种形式组成，分别为αα，ββ，γγ，αβ，αγ 五种同功酶［1］，这其中的γγ型烯醇化酶特异地存在神经元细胞或神经内分泌细胞，被称为神经元特异性烯醇化酶(neuron-specific enolase，NSE)。

NSE在脑组织神经元细胞中含量较高，大概占脑皮层烯醇化酶的40% ～65%［2］。

目前神经元特异性烯醇化酶的基因序列及氨基酸序列已被明确。

关于阿尔兹海默症研究方向被误导的英语作文

关于阿尔兹海默症研究方向被误导的英语作文全文共3篇示例，供读者参考篇1Over the past few decades, research on Alzheimer's disease has made significant progress in understanding the underlying mechanisms and potential treatments. However, in recent years, there has been growing concern that the focus of research may have been misguided, leading to limited advancements in the field. In this essay, we will discuss the possible reasons for this misdirection and propose alternative research directions that may hold promise for future breakthroughs in the treatment of Alzheimer's disease.One of the primary reasons for the misdirection of Alzheimer's disease research is the predominant focus on amyloid plaques as the primary cause of the disease. For many years, researchers have targeted these plaques in hopes of finding a cure for Alzheimer's disease. However, clinical trials targeting amyloid have largely been unsuccessful, raising questions about the validity of this approach. While amyloid plaques may play a role in the pathology of Alzheimer's disease,they may not be the sole cause of the cognitive decline seen in patients.Another reason for the misdirection of research is the lack of emphasis on other potential factors that may contribute to the development of Alzheimer's disease. For example, there is emerging evidence suggesting that neuroinflammation, mitochondrial dysfunction, and epigenetic changes may also play a role in the disease process. However, these factors have received limited attention in comparison to amyloid plaques, leading to a narrow focus in research efforts.In light of these limitations, it is crucial for researchers to explore alternative avenues of research that may shed light on the complex mechanisms underlying Alzheimer's disease. One promising research direction is the study of the gut-brain axis and its impact on neurodegenerative diseases. The gut microbiome has been shown to play a crucial role in brain health and cognitive function, and dysregulation of the gut-brain axis has been implicated in the pathogenesis of Alzheimer's disease. By investigating the interactions between the gut microbiome, inflammation, and neurodegeneration, researchers may uncover novel therapeutic targets for the treatment of Alzheimer's disease.In addition, research on the role of neuroinflammation in Alzheimer's disease holds promise for identifying new treatment strategies. Chronic inflammation in the brain has been linked to the progression of neurodegenerative diseases, including Alzheimer's disease. By targeting the inflammatory response in the brain, researchers may be able to slow or halt the cognitive decline associated with the disease. Furthermore, exploring the role of mitochondrial dysfunction and oxidative stress in Alzheimer's disease may provide insights into potential treatment options that target these pathways.Overall, it is essential for researchers to reconsider the current research direction in Alzheimer's disease and explore alternative avenues that may lead to new insights and breakthroughs in the field. By broadening the scope of research to include factors beyond amyloid plaques, such as the gut-brain axis, neuroinflammation, and mitochondrial dysfunction, researchers may uncover novel therapeutic targets for the treatment of Alzheimer's disease. Through collaborative efforts and innovative approaches, we can advance our understanding of this devastating disease and work towards finding effective treatments for individuals living with Alzheimer's disease.篇2Title: Misdirection in Alzheimer's Disease ResearchIntroduction:Alzheimer's disease is a progressive neurodegenerative disorder that primarily affects older individuals, causing memory loss, cognitive decline, and eventually leading to death. With no known cure, researchers around the world have been working tirelessly to unravel the mysteries of this devastating disease in hopes of finding a treatment or preventative measure. However, recent concerns have been raised about the direction of Alzheimer's disease research, with critics arguing that the focus has been misguided and potentially leading to dead-end research avenues.Misdirection in Alzheimer's Disease Research:One of the primary areas of concern in Alzheimer's disease research is the overemphasis on amyloid plaques as the primary cause of the disease. Amyloid plaques are abnormal clumps of protein fragments that accumulate between nerve cells in the brains of Alzheimer's patients. For decades, researchers have focused on developing drugs to target and eliminate amyloid plaques in the hopes of slowing or stopping the progression of the disease. However, despite numerous clinical trials and billions of dollars invested in anti-amyloid therapies, the resultshave been disappointing, with many drugs failing to show any significant benefit in patients.Critics argue that the focus on amyloid plaques has led to a neglect of other potential contributing factors to Alzheimer's disease, such as tau tangles, neuroinflammation, mitochondrial dysfunction, and vascular abnormalities. These factors may interact in complex ways to contribute to the development and progression of the disease, yet they have been largely overlooked in favor of the amyloid hypothesis. This narrow focus on amyloid plaques has not only resulted in failed drug trials but has also hindered progress in understanding the underlying mechanisms of the disease.Furthermore, the emphasis on amyloid plaques has overshadowed research into potential preventative measures, such as lifestyle interventions and environmental factors that may influence the risk of developing Alzheimer's disease. Studies have shown that modifiable lifestyle factors, such as diet, exercise, sleep, and social engagement, may play a significant role in maintaining brain health and reducing the risk of cognitive decline. Yet, these areas of research have received far less attention and funding compared to drug development targeting amyloid plaques.Moving Forward:In order to advance Alzheimer's disease research and make meaningful progress towards finding a cure or effective treatments, it is essential to broaden the focus beyond amyloid plaques and explore other potential mechanisms of the disease. Researchers should consider a more holistic approach that takes into account the complexity of Alzheimer's disease and the interactions between various biological, genetic, and environmental factors.Moreover, greater collaboration and data sharing among researchers is needed to accelerate progress and avoid duplication of efforts. By pooling resources and sharing information, researchers can effectively leverage the collective knowledge and expertise of the scientific community to address the multifaceted challenges of Alzheimer's disease.Conclusion:Alzheimer's disease is a complex and devastating condition that continues to elude effective treatment. The misdirection in research towards amyloid plaques has hindered progress and led to numerous failed drug trials. By broadening the focus and exploring alternative hypotheses, researchers can potentially uncover new insights into the disease and pave the way forinnovative treatments and preventative measures. It is imperative that the scientific community reevaluate its approach to Alzheimer's disease research and adopt a more comprehensive and collaborative strategy to accelerate progress in understanding and combating this debilitating condition. Only through a concerted effort and a reexamination of research priorities can we hope to make meaningful advancements in the fight against Alzheimer's disease.篇3Title: Misdirection in Alzheimer's Disease ResearchAlzheimer's disease is a devastating neurodegenerative disorder that affects millions of people worldwide. Despite decades of research and billions of dollars invested, a cure for Alzheimer's remains elusive. One of the reasons for this lack of progress may be that current research efforts are being misdirected, focusing on ineffective or inadequate strategies instead of exploring alternative avenues of investigation.One common approach in Alzheimer's research is to target the accumulation of amyloid-beta plaques in the brain, which is believed to be a hallmark of the disease. However, numerous clinical trials aimed at clearing these plaques have failed to showsignificant benefits in terms of cognitive function or disease progression. This has led some researchers to question whether amyloid-beta is truly the cause of Alzheimer's, or merely a byproduct of the disease process.Another area of research that has garnered significant attention is the role of tau protein in Alzheimer's. Abnormal accumulation of tau in the brain is associated with neuronal damage and cognitive decline, but efforts to develop treatments that target tau pathology have also met with limited success. It is possible that targeting tau may be more promising than targeting amyloid-beta, but more research is needed to fully understand its role in Alzheimer's.In addition to these mainstream research directions, there are other aspects of Alzheimer's disease that have received less attention but may hold the key to better treatments. For example, emerging evidence suggests that inflammation, vascular factors, and mitochondrial dysfunction may all contribute to the development and progression of Alzheimer's. By exploring these alternative mechanisms, researchers may uncover new therapeutic targets and strategies that could lead to more effective treatments for Alzheimer's.Furthermore, recent advances in genetics have revealed a complex interplay of genetic and environmental factors that contribute to the risk of developing Alzheimer's. By studying these factors in more detail, researchers may be able to identify novel pathways for intervention and personalized treatment approaches that take into account individual differences in disease progression.Overall, it is clear that the current research landscape in Alzheimer's disease is in need of a shift towards more innovative and diverse approaches. By exploring alternative mechanisms, thinking outside the box, and collaborating across disciplines, researchers may be able to make greater strides towards understanding the underlying causes of Alzheimer's and developing effective treatments. Only by challenging traditional assumptions and exploring new ideas can we hope to finally conquer this devastating disease.。

慢性应激中糖皮质激素及其受体在阿尔茨海默病中的作用

·综述·慢性应激中糖皮质激素及其受体在阿尔茨海默病中的作用刘欢1，李墅明1，顾小萍1,2作者单位1.南京医科大学鼓楼临床医学院南京2100082.南京大学医学院附属鼓楼医院麻醉科南京210008收稿日期2021-09-27通讯作者顾小萍xiaopinggu@nju. 摘要阿尔茨海默病（Alzheimer's disease，AD）的高患病率给家庭和社会带来沉重的负担。

最近很多动物研究表明慢性应激导致的糖皮质激素（glucocorticoid，GC）水平增加及其受体功能异常参与AD的病理进程，其涉及的机制包括增加Aβ沉积与tau蛋白过度磷酸化、损害突触可塑性、与小胶质细胞共同介导慢性炎症等。

给予糖皮质激素受体（glucocorticoid receptor，GR）拮抗剂能够改善AD动物模型的认知表现。

本文综述了GC及GR在AD病理中的可能作用机制，并为AD的研究和治疗提供新的思路与方法。

关键词慢性应激；糖皮质激素；糖皮质激素受体；阿尔茨海默病中图分类号R741；R741.02文献标识码A DOI10.16780/ki.sjssgncj.20210887本文引用格式：刘欢,李墅明,顾小萍.慢性应激中糖皮质激素及其受体在阿尔茨海默病中的作用[J].神经损伤与功能重建,2023,18(9):530-533.The Role of Glucocorticoid and Its Receptor in Alzheimer's Disease during Chronic Stress LIU Huan1,LI Shuming1,GU Xiaoping1,2.1.Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University,Nanjing210008,China;2.Department of Anesthesiology,Affiliated Drum Tower Hospital,Medical School of Nanjing University,Nanjing210008,ChinaAbstract Alzheimer's disease(AD)is characterized by a high prevalence,which imposes a heavy burden on families and society.Recently,many studies in animals have shown that chronic stress-induced elevation of glucocorticoid(GC)level and dysfunction of GC receptor(GR)are involved in the pathological process of AD. The involved mechanisms include increased deposition ofβ-amyloid(Aβ),hyperphosphorylation of tau protein, damaged synaptic plasticity,and co-mediation of chronic inflammation with microglia.Treatment with GR antagonists can improve the cognitive performance of animal models of AD.This article reviews the possible mechanisms of GC and GR in AD pathology,providing new insights and approaches for the research and treatment of AD.Keywords chronic stress;glucocorticoid;glucocorticoid receptor;Alzheimer's disease人口老龄化促使神经退行性疾病患病率大幅提升，其中较为常见的一类是阿尔茨海默病（Alzheimer'sdisease，AD）。

Neurology-2012-Anesthesia for endovascular treatment of acute ischemic stroke

Anesthesia for endovascular treatment of acute ischemic strokeMichael T.Froehler, MD,PhD Johanna T.Fifi,MD Arshad Majid,MD Archit Bhatt,MD Mingwen Ouyang,MD David L.McDonagh, MD ABSTRACTThe initial treatment of patients with acute ischemic stroke(AIS)focuses on rapid recanalization, which often includes the use of endovascular therapies.Endovascular treatment depends upon micronavigation of catheters and devices into the cerebral vasculature,which is easier and safer with a motionless patient.Unfortunately,many stroke patients are unable to communicate and sufficiently cooperate with the procedure.Thus,general anesthesia(GA)with endotracheal intu-bation provides an attractive means of keeping the patient comfortable and motionless during a procedure that could otherwise be lengthy and uncomfortable.However,several recent retro-spective studies have shown an association between GA and poorer outcomes in comparison with conscious sedation for endovascular treatment of AIS,though prospective studies are lacking.The underlying reasons why GA might produce a worse outcome are unknown but may include hemody-namic instability and hypotension,delays in treatment,prolonged intubation with or without neuro-muscular blockade,or even neurotoxicity of the anesthetic agent itself.Currently,the choice between GA and conscious sedation should be tailored to the individual patient,on the basis of neurologic deficits,airway and hemodynamic status,and treatment plan.The use of institutional treatment pro-tocols may best support efficient and effective care for AIS patients undergoing endovascular ther-apy.Important components of such protocols would include parameters to choose anesthetic modality,timeliness of induction,blood pressure goals,minimization of neuromuscular blockade,and planned extubation at the end of the procedure.Neurology®2012;79(Suppl1):S167–S173GLOSSARYAISϭacute ischemic stroke;CIϭconfidence interval;CSϭconscious sedation;GAϭgeneral anesthesia;ORϭodds ratio; tPAϭtissue plasminogen activator.The goal of early therapy for acute ischemic stroke(AIS)is to restore perfusion to ischemic areas of the brain.The introduction of IV fibrinolysis was a tremendous step forward in emergency patient care.1However,despite current professional education programs,enhanced public awareness,and integrated stroke care,only3%to8.5%of stroke patients are treated with IV tissue plasminogen activator(tPA).2Furthermore,fewer than half of patients with large-artery occlusions who are treated with tPA experience recanalization from thrombolysis.3 Thus,there is a need for additional reperfusion strategies.Endovascular therapy offers a more direct approach to the occlusive lesion.Furlan et al.4 initially showed that the intra-arterial administration of thrombolytics led to improved out-comes in patients with large-artery ter,mechanical thrombectomy was shown to be more effective in terms of recanalization,5,6with more recent success rates of81%to84%.7 Currently,there are an array of endovascular treatment options,including intra-arterial phar-macologic fibrinolysis,guidewire maceration,clot retrieval,thrombus aspiration,angioplasty, and stenting.Choosing from the available options for endovascular stroke treatment is difficult and is usually made on a case-by-case basis,as there are often important technical differences From the Neuro Interventional Service(M.T.F.),Department of Neurology,University of Iowa Hospitals and Clinics,Iowa City;Departments of Neurology and Radiology(J.T.F.),St.Luke’s–Roosevelt Hospital,New York,NY;Hyper Acute Stroke Research Centre(A.M.),Department of Neurology,Salford Royal NHS Foundation Trust,Salford,UK;Department of Neurosciences(A.B.),Spectrum Health Medical Group,Grand Rapids,MI;Department of Anesthesiology(M.O.),Nanfang Hospital,Southern Medical University,Guangzhou,China;and Division of Neuroanesthesiology(D.L.M.),Duke University Medical Center,Durham,NC.Go to for full disclosures.Disclosures deemed relevant by the authors,if any,are provided at the end of this article.Correspondence&reprint requests to Dr.McDonagh: david.mcdonagh@between devices and their use.For example, some devices may require more precision in their deployment,others may cause more pa-tient discomfort,and some may require lon-ger procedure times.Patients with stroke often have significant neurologic impairment;they may be aphasic and unable to communicate,may be paretic, or may experience vertigo—any of which may cause significant distress.This can make it dif-ficult for the patient to tolerate a procedure that requires lying still for a prolonged period of time.And if the patient is unable to remain motionless,it can cause significant degradation in image quality,inability to utilize roadmap functions,and even trauma and vessel damage related to movement of the catheter.To address these considerations,anesthesia is often utilized in neurointervention.Anesthesia may come in the form of conscious sedation(CS),with ad-ministration of low-dose analgesics and hypnot-ics that may improve the comfort of the patient but may not be adequate to fully immobilize the patient.General anesthesia(GA)with endotra-cheal intubation allows for a completely mo-tionless patient but may be associated with significant disadvantages.In particular,several recent studies have demonstrated worse outcomes after endovas-cular treatment in AIS patients with GA,in comparison with CS.8–10If this finding is true, then the choice of anesthesia during acute stroke treatment may have important ramifications. Thus,we shall first review the recent clinical data,before speculating on the potential mecha-nisms underlying worse outcomes with GA, which might include hemodynamic changes, neurotoxicity,delays in treatment,or prolonged intubation.A better understanding of these and other considerations should allow the develop-ment of rational protocols for the use of anesthe-sia in patients with AIS.Clinical studies.There have been no prospective, randomized studies comparing GA with CS in en-dovascular treatment of AIS or of any other cere-brovascular disease.However,several recently published retrospective studies have provided some compelling data and ignited considerable de-bate on this issue.11,12Currently,it appears that endovascular neurolo-gists are mixed in their use of GA vs CS for patients undergoing interventional therapy for AIS.In a re-cent survey of the members of the Society of Vascular and Interventional Neurologists,McDonagh et al.13 found that only6%of the respondents used GA ex-clusively.However,55%of respondents believed that GA is mandatory when using mechanical thrombec-tomy.This preference for GA was based on the assump-tion that limiting movement makes the interventional procedure safer and more efficacious.Although GA and immobility allow greater image quality and decrease procedural time,the greatest perceived limitation was a delay in starting the procedure.The relationship between periprocedural sedation and outcome has been assessed by3recent studies. Nichols et al.8studied the sedation practices in the Interventional Management of Stroke II Trial.Of81 patients,sedation data were available for75.A seda-tion classification scale was used to classify the extent of sedation used:1ϭno sedation,2ϭmild seda-tion,3ϭheavy sedation,and4ϭpharmacologic paralysis.Fifty-three percent(nϭ40)were given no sedation(grade1)and23%(nϭ17)were intubated/ paralyzed(grade4).Patients in the higher sedation categories had higher baseline NIH Stroke Scale scores,suggesting more severe baseline stroke sever-ity.Patients in lower sedation categories had better outcomes,more frequent reperfusion rates,and lower mortality.When accounting for baseline neu-rologic status with use of multivariate analysis,mild or no sedation(grade1or2)was associated with a good clinical outcome(odds ratio[OR]5.7;95% confidence interval[CI]1.5–12.3),and heavy seda-tion or paralysis(grade3or4)was an independent predictor of death(OR5.0;95%CI1.3–18.7).Jumaa et al.9retrospectively reviewed126patients who had received endovascular therapy for AIS due to middle cerebral artery occlusion.Level of sedation was classified as intubated(42%)vs nonintubated (58%).Nonintubation was associated with shorter ICU stays(3.2vs6.5days;pϭ0.0008),lower in-farct volume(OR0.25;pϭ0.004),good clinical outcome(OR3.06;pϭ0.042),and lower in-hospital mortality(OR0.32;pϭ0.011).A nonsig-nificant difference in complications was observed, with6%in the intubated group and15%in the non-intubated group(pϭ0.13).The largest study was performed by Abou-Chebl et al.,10who recently reported the results of a multi-center,retrospective review of980endovascular acute stroke cases.GA was used in44%of all pa-tients,and these patients were more likely to have ca-rotid terminus occlusions and higher NIH Stroke Scale scores.The intracranial hemorrhage rate was no differ-ent between GA and CS.However,GA was an inde-pendent predictor of poor neurologic outcome(OR 2.33;95%CI1.63–3.44)and higher mortality(OR 1.68;95%CI1.23–2.30)in multivariate analyses.Limited published data suggest that CS may be adequate and safe in patients undergoing neurointer-ventional procedures for diseases other than AIS. Ogilvy et al.14reported using CS in92.2%of elective aneurysm embolizations in340patients,with low morbidity and mortality rates and short hospital stays.Additionally,complications and effectiveness were similar between GA and CS among patients un-dergoing angioplasty and stenting for intracranial stenosis.15Of course,patients undergoing these elec-tive treatments are typically much more comfortable and cooperative than patients with AIS,and these procedures are not performed in the emergent set-ting.Nonetheless,these reports highlight the feasibil-ity of performing neurointerventional procedures in the nonanesthetized patient.These retrospective data provide some evidence that outcomes in endovascular treatment of AIS may be worse with the use of GA.Of course,prospective data will be needed to definitively address this issue, although recruitment in a randomized trial may be difficult.But if the current data from these3trials are accurate,what might be the reason for the differ-ence in outcomes between GA and CS?Some possi-bilities might include hemodynamic changes,delays in treatment,prolonged intubation,neuromuscular blockade,and neurotoxicity of the anesthetic agents themselves.Hemodynamic effects of GA.GA has a range of sys-temic and cerebral effects,but probably the most un-welcome effect in acute stroke is hypotension.In the setting of AIS,an occluded artery causes focal cere-bral ischemia,and a reduction in systemic blood pressure(cerebral perfusion pressure)may lead to re-duction in collateral perfusion,16which could hasten the progression to complete infarction.17Typically, the most pronounced drop in blood pressure occurs immediately after induction.This decline in blood pressure is associated with lower baseline blood pres-sure,the use of certain anesthetic agents,and general health status.18Postinduction hypotension,even in elective surgery,has been associated with prolonged hospital stays and increased mortality.18Thus,when GA is used in acute stroke patients,blood pressure should be strictly controlled,particularly at the time of induction,with use of predefined parameters but accounting for the baseline blood pressure,stroke syndrome,and the patient’s general health status.In particular,the patient’s baseline blood pressure is of critical importance,as cerebral blood flow is autoregulated only within a limited range,and hypo-tension beyond this range can lead to cerebral isch-emia,especially in the setting of stroke and decreased collateral availability.Therefore,any blood pressure reduction at the time of anesthesia induction could impair potentially important collateral perfusion. The safest approach given the unknown level of risk with blood pressure reduction is to assume that the patient has tenuous collateral perfusion and to keep the blood pressure at the preinduction baseline.In practical terms,this translates into maintaining hy-pertension during the AIS intervention.Although all anesthetic agents cause some hypo-tension,they vary in their effects on the cerebral vas-culature and intracranial pressure.Specifically,the halogenated inhalational anesthetic agents(isoflu-rane,sevoflurane,and desflurane)are cerebral vasodi-lators and do not maintain the normal coupling of cerebral blood flow with cerebral metabolic rate.19–21 Thus,although they suppress the cerebral metabolic rate,they cause a relative cerebral hyperemia.This can be a significant concern in patients with elevated intracranial pressure,although not in the majority of AIS patients who have normal intracranial pressure. It should be noted that controlled ventilation with hypocapnia can offset this vasodilatory effect of the halogenated inhaled anesthetics.22In contrast to the halogenated agents,propofol better preserves cerebral autoregulation.19,23There-fore,as the cerebral metabolic rate is reduced with propofol,the cerebral blood volume is reduced pro-portionately.Nitrous oxide should be avoided in acute stroke interventions because of concerns for ex-acerbating any cerebrovascular air emboli entrained during the procedure.24,25Both the halogenated anesthetic agents and propofol cause dose-dependent systemic hypotension due to vasodilatation,21,24which is particularly pro-nounced at the time of induction.Propofol causes more hypotension postinduction than other induc-tion agents such as etomidate,18whose use may be preferred in the setting of AIS.This drop in cerebral perfusion pressure often necessitates the concomitant use of vasopressor agents.Unfortunately,we have no adequate point-of-care cerebral perfusion monitors to guide hemodynamic therapies intraoperatively during AIS interventions.Therefore,it is critical to determine blood pressure parameters before induc-tion and to rapidly correct hypotension with pres-sors,on the basis of predefined blood pressure goals. Finally,other factors that could further contribute to excessive vasoconstriction or vasodilation,such as hy-pocapnia or hypercapnia,should be avoided.Analgesia is an important component of GA and of CS.An opioid is typically employed for this pur-pose,and short-acting opioids such as remifentanil,because of its lack of accumulation(i.e.,lack of con-text sensitivity),are well suited to acute stroke inter-ventions.Hypotension is again a side effect that must be monitored closely and counteracted with pressor agents such as phenylephrine,norepinephrine,or ephedrine.Logistical considerations.The emergent delivery of endovascular therapy to an occluded intracranial ves-sel requires an efficient health care delivery system involving multiple clinical services within the hospi-tal working together.Orchestrating care among the emergency department,imaging,stroke team,and interventional service can be challenging and time-consuming.The immediate availability of an experi-enced anesthesia team to provide care for patients as a Level1emergency is important.Unfortunately, this is not always the case in many centers.The endo-vascular suite is commonly located apart from main operating rooms,stretching the capability of the an-esthesia team to rapidly respond,particularly at times when staffing levels are limited.The equipment and medications required for delivery of anesthetic care should be readily accessible within the neurointer-ventional area.Any factor that leads to a delay in the initiation of the procedure is detrimental.The famil-iarity of the anesthesia team with acute stroke inter-vention and the endovascular suite environment can vary significantly,especially during off hours.There-fore,discussion of parameters such as blood pressure goals and foreseeable time course for anesthetic in-duction and endotracheal intubation should take place in advance.CS is commonly used in many centers worldwide for AIS interventions.12,13,26However,various concerns arise with the use of CS.The optimal management of sedation to produce a cooperative,nonmoving patient varies in difficulty from patient to patient.In addition, patients have typically not fasted as they would for an elective cerebral endovascular procedure.This raises concerns for pulmonary aspiration of gastric contents in the setting of sedation and supine positioning.27 The need for emergent endotracheal intubation may result from any combination of oversedation,neuro-logic decline,airway compromise,or agitation. Emergent conversion to GA during the endovascular procedure may result in hypoxia or aspiration and necessitates the presence of a practitioner skilled in endotracheal intubation.General anesthesia is a logical and seemingly at-tractive solution to many of these issues,since the patient will be deeply sedated with a protected airway (endotracheal intubation).However,there are poten-tially significant downsides.As discussed,the use of GA must not delay the delivery of reperfusion ther-apy.In addition,there is a loss of the neurologic ex-amination and the procedure must proceed to a radiographic endpoint rather than a clinical end-point.As discussed above,the requirement for endo-tracheal intubation during GA has been associated with longer intensive care unit stays,pneumonia,and increased mortality in retrospective studies.8,9This may be due in part to the transport of patients to the intensive care unit while intubated after the proce-dure,leaving the weaning to occur at a later time. Development of ventilator-associated pneumonia is known to increase with longer duration of intubation.28 Extubation immediately after the procedure to allow for neurologic examination and avoid potential complica-tions should be the goal when possible. Procedural paralysis.The endovascular procedure re-quires minimal patient movement for safe,efficient delivery of catheters and devices for thrombolysis and thrombectomy,for2major reasons.First,patient motion creates imaging artifact,resulting in angio-graphic images that are difficult to interpret.Time lost repeating imaging to obtain a clear picture of the anatomy and occlusion site can add up to significant delays.Second,patient motion during critical parts of the procedure while mechanical instrumentation is in the cerebral vasculature can lead to devastating complications.For the purposes of minimizing pa-tient motion,GA is superior to CS or monitored anesthesia care.Anesthesiologists utilize neuromuscular blocking agents to facilitate endotracheal intubation and pro-vide a margin of safety during these procedures,al-lowing optimal visualization of the cervical and intracranial vasculature.For the acute stroke patient in whom a neurologic examination is often desired immediately after the procedure,the neuromuscular blocking agent used should be readily reversible. Intermediate-acting agents such as cisatracurium,ve-curonium,and rocuronium are preferred.21,24Depth of neuromuscular blockade should be monitored during the procedure so that reversal of the blockade can be performed at the end of the procedure and ongoing endotracheal intubation can be avoided.In addition,older agents such as atracurium,which is associated with histamine release(causing hypoten-sion and decreased cerebral perfusion pressure), should be avoided.29Anesthetic neuroprotection or neurotoxicity?To add further complexity to the question of GA in AIS inter-ventions,we must consider longer-term effects of the anesthetic agents themselves.There is a large literature on the neuroprotective effects of anesthetic agents, spanning3decades,mostly relating to the barbiturates and isoflurane.30In fact,there is strong evidence for the neuroprotective effect of isoflurane in rodent models offocal ischemia(i.e.,acute stroke).31Human trials of bar-biturate neuroprotection after cardiac arrest32were negative,but no human evidence exists for the neuro-protective or neurotoxic effects of general anesthetics in acute ischemic stroke.More recently,concern has grown regarding the potential neurotoxic effects of anesthetics,particu-larly isoflurane.33–36There is evidence from cell cul-ture and rodent models that isoflurane promotes oligomerization of␤-amyloid,one of the pathophys-iologic processes in Alzheimer disease,and causes neurotoxicity in both neonatal and elderly ani-mals.33,34Nitrous oxide and ketamine have also been implicated,and data from animal studies indicate that toxicity may be mediated by NMDA receptor antagonist(e.g.,ketamine)–induced vacuolization of neurons of adult and aged rodents.35,36Human stud-ies are under way in at-risk populations.To our knowledge,there are no data to date re-garding anesthetic neurotoxicity in acute ischemic stroke.Whether common perioperative neurologic complications such as delirium and postoperative cognitive dysfunction are related to anesthetic neuro-toxicity or other factors is similarly unknown.37 It will be difficult to directly study the neuropro-tective or neurotoxic effects of general anesthetics in patients with AIS.However,outcome studies in isch-emic stroke populations are needed to define the short-term and long-term impact of general anesthetics on the nervous system.In addition,animal stroke models should also be utilized to explore the potential mecha-nisms of neurotoxicity of anesthetic agents.As an aside,the discussion of neuroprotection would be incomplete without considering therapeutic hypothermia.The use of GA for AIS interventions would facilitate the rapid induction of therapeutic hypothermia.However,to date,only early stage fea-sibility trials have been conducted,38and there is cur-rently no convincing human evidence to suggest that AIS patients benefit from cooling.Current goals are to maintain normothermia,while avoiding hyper-thermia,in AIS interventions.DISCUSSION Acute stroke therapy has evolved sig-nificantly.Entire systems of care have developed to support the delivery of recanalization therapies, which have included physician,hospital,corporate, and legislative efforts.39,40Although these systems have certainly improved the structure of care and re-sources available to those of us who treat ischemic stroke,the treatment of each individual patient still brings new challenges to the rapid delivery of appro-priate therapy.One such challenge is the decision regarding anesthesia for AIS patients undergoing en-dovascular treatment.Making this decision involves an assessment of neurologic status,airway,ability to cooperate with the procedure,anticipated technique and procedure time,planned postprocedure care, and other factors.And beyond these individual pa-tient factors,we must consider the general risks of GA,including delay to treatment,hemodynamic in-stability,and the loss of the neurologic examination during the procedure.In light of recent data,we must also consider the possibility that the use of GA may be associated with poorer outcomes.Random-ized controlled trials of the use of GA in AIS inter-ventions would provide the highest level of evidence to guide therapy.However,in the interim,the inclu-sion of sedation type,factors influencing choice of sedation,and complications related to sedative mo-dality should be prospectively gathered in any AIS intervention trials.This will provide intermediate-level evidence that is superior to what is currently available in regard to the impact of GA on outcome after AIS interventions.Until we have better evidence to guide us,we must individualize choice of anesthesia to each pa-tient.GA may be more appropriate for patients with severe deficits,airway compromise,or bulbar dys-function.CS may be more appropriate for patients with milder deficits or those with tenuous hemody-namic status.To minimize the potentially negative effects of GA with endotracheal intubation,the neu-rointerventionalist and anesthesiologist should plan to extubate at the end of the case unless there is a contraindication,and agree upon hemodynamic pa-rameters before the start of the case.Ideally,these goals would be supported by institutional treatment protocols that would avoid the need for lengthy plan-ning and discussion prior to the start of each case. Indeed,the use of GA vs CS can be based on a proto-col that incorporates clinical status,anticipated pro-cedural technique,and planned postprocedure care. The use of standardized protocols in treating for ischemic stroke patients does improve their care,39 and we would advocate the use of an anesthesia pro-tocol to further support safe and efficient endovascu-lar treatment for patients with AIS.AUTHOR CONTRIBUTIONSDr.Froehler and Dr.Fifi:drafting/revising the manuscript,study concept or design,analysis or interpretation of data.Dr.Majid:drafting/revising the manuscript.Dr.Bhatt and Dr.Ouyang:drafting/revising the manu-script,study supervision.Dr.McDonagh:drafting/revising the manu-script,study concept or design,analysis or interpretation of data, acquisition of data.ACKNOWLEDGMENTThe authors thank Dr.Harold P.Adams for comments on the manuscript.DISCLOSUREDr.Froehler has received funding from the A.P.Giannini Foundation and from the US Food and Drug Administration as a medical officer.Dr.Fifi received a speaker’s honorarium and travel expenses from Penumbra, Inc.Dr.Majid has served as an Associate Editor for Neurohospitalist and served on the speakers bureau for Boehringer Ingelheim.Dr.Bhatt and Dr.Ouyang report no disclosures.Dr.McDonagh has served on the Edi-torial Board of Journal of Neurosurgical Anesthesiology;received consulting fees from Cephalogics Corporation,LLC;and received research support from the Alzheimer’s Disease Research Foundation.Go to Neurology. org for full disclosures.Received September21,2011.Accepted in final form December1,2011.REFERENCES1.The National Institute of Neurological Disorders andStroke rt-PA Stroke Study Group.Tissue plasminogen ac-tivator for acute ischemic stroke.N Engl J Med1995;333: 1581–1587.2.Reeves MJ,Arora S,Broderick JP,et al.Acute stroke carein the US:results from4pilot prototypes of the Paul Cov-erdell National Acute Stroke Registry.Stroke2005;36: 1232–1240.3.Rha JH,Saver JL.The impact of recanalization on isch-emic stroke outcome:a meta-analysis.Stroke2007;38: 967–973.4.Furlan A,Higashida R,Wechsler L,et al.Intra-arterialprourokinase for acute ischemic stroke:the PROACT II study:a randomized controlled trial:Prolyse in Acute Ce-rebral Thromboembolism.JAMA1999;282:2003–2011.5.Smith WS,Sung G,Starkman S,et al.Safety and efficacyof mechanical embolectomy in acute ischemic stroke:re-sults of the MERCI trial.Stroke2005;36:1432–1438. 6.The penumbra pivotal stroke trial:safety and effectivenessof a new generation of mechanical devices for clot removal in intracranial large vessel occlusive disease.Stroke2009;40:2761–2768.7.Costalat V,Machi P,Lobotesis K,et al.Rescue,combined,and stand-alone thrombectomy in the management of large vessel occlusion stroke using the solitaire device:a prospective50-patient single-center study:timing,safety, and efficacy.Stroke2011;42:1929–1935.8.Nichols C,Carrozzella J,Yeatts S,Tomsick T,Broderick J,Khatri P.Is peri-procedural sedation during acute stroke therapy associated with poorer functional outcomes?J Neurointerv Surg2010;2:67–70.9.Jumaa MA,Zhang F,Ruiz-Ares G,et parison ofsafety and clinical and radiographic outcomes in endovas-cular acute stroke therapy for proximal middle cerebral ar-tery occlusion with intubation and general anesthesia versus the nonintubated state.Stroke2010;41:1180–1184.10.Abou-Chebl A,Lin R,Hussain MS,et al.Conscious seda-tion versus general anesthesia during endovascular therapy for acute anterior circulation stroke:preliminary results from a retrospective,multicenter study.Stroke2010;41: 1175–1179.11.Molina CA,Selim MH.General or local anesthesia duringendovascular procedures:sailing quiet in the darkness or fast under a daylight storm.Stroke2010;41:2720–2721.12.Gupta R.Local is better than general anesthesia duringendovascular acute stroke interventions.Stroke2010;41: 2718–2719.13.McDonagh DL,Olson DM,Kalia JS,Gupta R,Abou-Chebl A,Zaidat OO.Anesthesia and sedation practices among neurointerventionalists during acute ischemic stroke endovascular therapy.Front Neurol2010;1:118.14.Ogilvy CS,Yang X,Jamil OA,et al.Neurointerventionalprocedures for unruptured intracranial aneurysms underprocedural sedation and local anesthesia:a large-volume, single-center experience.J Neurosurg2011;114:120–128.15.Chamczuk AJ,Ogilvy CS,Snyder KV,et al.Elective stent-ing for intracranial stenosis under conscious sedation.Neurosurgery2010;67:1189–1193.16.Bang OY,Saver JL,Alger JR,Starkman S,Ovbiagele B,Liebeskind DS.Determinants of the distribution and se-verity of hypoperfusion in patients with ischemic stroke.Neurology2008;71:1804–1811.17.Ginsberg MD,Pulsinelli WA.The ischemic penumbra,injury thresholds,and the therapeutic window for acute stroke.Ann Neurol1994;36:553–554.18.Reich DL,Hossain S,Krol M,et al.Predictors of hypoten-sion after induction of general anesthesia.Anesth Analg 2005;101:622–628.19.Kaisti KK,Långsjo¨JW,Aalto S,et al.Effects of sevoflu-rane,propofol,and adjunct nitrous oxide on regional cere-bral blood flow,oxygen consumption,and blood volume in humans.Anesthesiology2003;99:603–613.20.Dinsmore J.Anaesthesia for elective neurosurgery.Br JAnaesth2007;99:68–74.21.Lee CZ,Litt L,Hashimoto T,Young WL.Physiologicmonitoring and anesthesia considerations in acute isch-emic stroke.J Vasc Interv Radiol2004;15:S13–S19. 22.McCulloch TJ,Boesel TW,Lam AM.The effect of hypo-capnia on the autoregulation of cerebral blood flow during administration of isoflurane.Anesth Analg2005;100: 1463–1467.23.Adembri C,Venturi L,Pellegrini-Giampietro DE.Neuro-protective effects of propofol in acute cerebral S Drug Rev2007;13:333–351.24.Young WL.Anesthesia for endovascular neurosurgery andinterventional neuroradiology.Anesthesiol Clin2007;25: 391–412.25.Varma MK,Price K,Jayakrishnan V,Manickam B,KessellG.Anaesthetic considerations for interventional neurora-diology.Br J Anaesth2007;99:75–85.26.Brekenfeld C,Mattle HP,Schroth G.General is betterthan local anesthesia during endovascular procedures.Stroke2010;41:2716–2717.27.Practice guidelines for preoperative fasting and the use ofpharmacologic agents to reduce the risk of pulmonary aspi-ration:application to healthy patients undergoing elective procedures:a report by the American Society of Anesthesi-ologist Task Force on Preoperative Fasting.Anesthesiology 1999;90:896–905.28.Byers JF,Sole ML.Analysis of factors related to the devel-opment of ventilator-associated pneumonia:use of existing databases.Am J Crit Care2000;9:344–349.29.Schramm WM,Papousek A,Michalek-Sauberer A,CzechT,Illievich U.The cerebral and cardiovascular effects of cisatracurium and atracurium in neurosurgical patients.Anesth Analg1998;86:123–127.30.Bickler PE,Patel PM.Anesthetic neuroprotection:somethings do last.Anesthesiology2007;106:8–10.31.Sakai H,Sheng H,Yates RB,Ishida K,Pearlstein RD,Warner DS.Isoflurane provides long-term protection against focal cerebral ischemia in the rat.Anesthesiology 2007;106:92–99.32.Brain Resuscitation Clinical Trial I Study Group.Random-ized clinical study of thiopental loading in comatose survivors of cardiac arrest.N Engl J Med1986;314:397–403.33.Xie Z,Culley DJ,Dong Y,et al.The common inhalationanesthetic isoflurane induces caspase activation and in-。

麻醉药物的神经保护作用与神经毒性研究进展

麻醉是使用药物或其他方法使患者整体或局部暂时失去感觉，以达到无痛目的，为手术和其他治疗创造条件的一种方法。

麻醉药物对于中枢神经系统具有一定的保护作用，如对缺血再灌注（isch⁃emia-reperfusion，IR）损伤、创伤性脑损伤、脑卒中、蛛网膜下腔出血、神经外科手术期间脑的保护[1-2]。

但也具有一定的大脑毒性和损伤作用，包括抑制和破坏婴幼儿、小儿神经系统发育，导致记忆、学习功能障碍，致使老年患者发生术后谵妄乃至长期的认知功能障碍等[3-4]。

因此，确切阐明麻醉药物对中枢神经系统的保护作用和毒性，将为临床麻醉药物的选择提供参考，本文就此综述如下。

1麻醉药物的分子靶点1.1化学门控离子通道化学门控离子通道可分为胆碱类、胺类、氨基酸类等。

麻醉药物主要作用于氨基酸类受体发挥作用。

大多数的麻醉药物都可抑制N-甲基-D-天冬氨酸（N-methyl-D-aspartic acid，NMDA）受体，和兴奋γ-氨基丁酸A型（gamma absorptiometry aminobutyricacid，GABAA）受体。

1.1.1NMDA受体NMDA受体是离子型谷氨酸受体的一个亚型，它由NR1和NR2（2A、2B、2C和2D）亚基组成[5]。

氯胺麻醉药物的神经保护作用与神经毒性研究进展胡雨蛟1，吴安国2，欧册华3（西南医科大学：1麻醉系；2中药活性筛选及成药性评价泸州市重点实验室；3附属医院疼痛科，四川泸州646000)摘要麻醉药物具有神经保护作用，同时也有一定的神经毒性，如何实现其神经保护作用，减少神经毒性，成为临床麻醉医生面临的重要难题。

本文从麻醉药物的作用分子靶点、神经保护作用、神经毒性以及如何减轻神经毒性等方面进行了综述，以期为临床麻醉用药选择提供参考。

关键词麻醉药物；神经保护；神经毒性；中枢神经系统中图分类号R971.2；R614.1文献标志码A doi：10.3969/j.issn.2096-3351.2021.02.018Research progress in neuroprotection and neurotoxicity of anestheticsHU Yujiao1，WU Anguo2，OU Cehua31.Department of Anesthesia；2Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chi⁃nese Materia Medica，School of Pharmacy；3Department of Pain of Affiliated Hospital of Southwest Medical University，Luzhou646000，Sichuan Province，ChinaAbstract Anesthetics possess neuroprotective effects but also certain neurotoxicity.How to achieve neuropro⁃tection and reduce neurotoxicity concurrently has become an important problem for anesthesiologists.This article re⁃views the molecular targets，neuroprotective effects，and neurotoxicity of anesthetics，as well as how to reduce the neurotoxicity of anesthetics，in order to provide a reference for the selection of anesthetics in clinical practice.Keywords Anesthetics；Neuroprotection；Neurotoxicity；Central nervous system基金项目：国家自然科学基金青年基金项目（81903829）；国家级大学生创新创业训练计划项目（202010632047）；泸州市人民政府-西南医科大学联合项目（2018LZXNYD-ZK42）第一作者简介：胡雨蛟，本科生。

The Neutrality, Impartiality and Independence of Arbitrators 仲裁员的中立性、公正性和独立性

International Commercial Dispute ResolutionSummative EssayESSAY TITLE:“In common parlance, neutrality is often equated with impartiality. Any such assimilation, however, would be incorrect, since neutrality and impartiality are intrinsically different. At the risk of oversimplification, neutrality may be defined as an objective status, i.e.the likelihood that the arbitrator is, and will remain, wholly equidistant in thought and action throughout the arbitral proceedings.Impartially, on the contrary partakes more of subjective status, to be tested in the context of the concrete relations existing between the arbitrator(s) and each individually party. It follows from that that one can be impartial without being neutral; and conversely, that no arbitrator may be deemed neutral if he/she is behaving partially.’*A.J. Van Den Berg, ‘International Dispute Resolution: Towards an International Arbitration Culture’ (Kluwer, 1998), p. 42.Critically discuss the above statement.1.0 IntroductionArbitration, as defined by Professor Vries, is “a mode of resolving disputes by one or more persons who derive their power from the agreement of the parties”1, and the history of it can be traced back to ancient Greece.2Over the past two decades, an increasing number of parties are submitting disputes arising from international contracts to arbitration.3This tendency is confirmed by e mpirical surveys4, which shows that arbitration has gradually superseded litigation as the favorable dispute resolution mechanism in cross-border 1Henry P. de Vries, ‘International Commercial Arbitration: A Contractual Substitute for National Courts’ (1982) 57 Tulane Law Review, 432Gary B. Born, International Commercial Arbitration (3rd edn, Alphen aan den Rijn: Kluwer Law International, 2008) 83The International Chamber of Commerce’s International Court of Arbitration received requests for 32 now arbitrations in 1956, 210 arbitrations in 1976,529 arbitrations in 1999 and 599 arbitrations in 2007-a roughly 20-fold increase over the past 50 years. Similarly, in 1980, the American Arbitration Association administered approximately 100 international arbitrations; in 1993, 207 such arbitrations; in 2000, 510 international arbitrations; and in 2007, 621 international arbitrations. Other institutions show similar growth in case loads.4C. Drahozal & R. Naimark, Towards A Science of International Arbitration: Collected Empirical Research Appendix 1, 341 (2005)commercial transactions.5The popularity of international arbitration can be attributed to several outstanding advantages it offers in comparison with litigation. The most valued features of international arbitration are the parties’ autonomy in the selection of the “private judges”, the maximum degree of procedural flexibility and the more reliable enforceability of arbitral awards. However, some of these merits could become disadvantages as well, when viewed from a different perspective. For example, unlike court judgments which can be retried or reconsidered, the decision of arbitration is final and binding, and the grounds for challenging a valid award are narrowly confined to issues of procedural fairness, jurisdiction and public policy.6Dispensing with judicial review significantly reduces both litigation costs and delays. On the other hand, the finality of arbitration also means that a wildly eccentric or an apparent unjust arbitral decision cannot readily (if ever) be rectified.7Basically, the parties exchange the opportunity of appellate review for the benefits of speed, economy and finality.8Moreover, compared to their judicial counterparts, arbitrators are granted with more discretion. According to UNCITRAL Model Law9, the arbitral tribunal can not only rule on its own jurisdiction, but also can determine the applicable law and the arbitral proceedings in the absence of parties’ consensual agreement. As Pierre Lalive said, “Arbitration is only as good as the arbitrators.”10The reputation and acceptability of international arbitration largely depends upon the quality and skill of the chosen arbitrators.11Hence, choice of persons who compose the arbitral tribunal is vital, and is often the most decisive step in arbitration.12In the theory of arbitration, neutrality, independence and impartiality have always been deemed as the underlying principles in the code of arbitrators’ conduct. Anecdotal evidence indicates that business users generally prefer the equitable procedure and fair5Adrian Winstanley, ‘Why arbitration institutions matter’ in Law in transition: Focus on contract enforcement (2011) 33 </downloads/research/law/lit012.pdf> accessed 17 March 20136Gary B. Born, supra note 2, at 827ibid8ibid p. 17439UNCITRAL Model Law on International Commercial Arbitration Art.16,2010Pierre Lalive, ‘On the Neutrality of the Arbitrator and of the Place of Arbitration’, in Swiss Essays on International Arbitration (1984) 2311J.D.M. Lew, L.A. Mistelis and S.M. Kroll, Comparative International Commercial Arbitration (Kluwer, 2003), 232 12Alan Redfern & Martin Hunter, Law and Practice of International Commercial Arbitration (4th edn, London : Sweet & Maxwell, 2004), 10result of arbitration, even at the expense of speed, cost and the expertise of arbitrators.13 Unfortunately, although major institutional arbitration rules and national arbitration law explicitly set up mandatory requirements that the arbitrator should act neutrally, impartially and independently, none of them further elaborate on what neutrality or impartiality entails, triggering intense academic debates of the interpretation of these three notions.14 Besides, while it is true that arbitrator bias constitutes what may well be a central basis for overturning an arbitrator's award, the absence of definite and uniform standards for evaluating the arbitrator’s performance leads to the consequence that some arbitrators were not disciplined for their misconduct.15It has been sarcastically suggested that "barbers and taxidermists are subject to far greater regulation than [arbitrators]."16The institutional deficiencies vastly tarnish the overall profile of arbitrator group and reduce peoples’ confidence in the impartiality of arbitral award, which further hinder the positive role of arbitrators in the development of international commercial dispute resolution. Thus, the main purpose of this essay is to research on the neutrality, impartiality and independence of arbitrators. In order to accomplish this, the essay will be divided into three parts. The first part will address the definition of the three terms as well as the distinction and connection between them. The current legislation of the above three key elements will also be numerated in this section. The second part will examine the different test applied by national courts and leading arbitration institutions to assess the arbitrator’s impartiality and independence. Finally, the essay intends to discuss the safeguard system against bias of arbitrators.2.0 The Concept and Legislation of Independence, Impartiality and Neutrality13Bühring-Uhle, A Survey on Arbitration and Settlement in International Business Disputes, in C.Drahozal &R.Naimark, Towards A Science of International Arbitration: Collected Empirical Research (2005) 2514Amina Rustamova, ‘Neutrality of Arbitrators’ (Central European University, 10 April 2009)http://www.etd.ceu.hu/2009/rustamova_amina.pdf accessed 7 April 201315AT&T Corp v Saudi Cable Co. [2000] 1 Lloyd's Rep. 22 In this case, the English court characterized as simply a "most unfortunate secretarial error" the failure by a Canadian arbitrator to disclose his directorship in a company that bid on the very contract in dispute.16Reuben, Richard C, Constitutional Gravity: A Unitary Theory of Alternative Dispute Resolution and Public Civil Justice (2000) 47 UCLA Law Review, 10132.1 The Definition and Relation of Independence, Impartiality and Neutrality As mentioned earlier, the uncertainty in the terminology of these three notions has generated extensive academic discussion, accompanied by different voices. The following paragraph covers the common perception of scholars towards the explanation of these terms.2.1.1 IndependenceThe concept of ‘dependence’ is concerned exclusively with the question arising out of the relationship.17“Independence” requires an arbitrator to be free of any involvement or relationship with any of the parties, whether personal, social or financial.18This approach is in line with the IBA Rules of Ethics19. In addition, the rules also extend the independence requirement of arbitrators to relationships with someone closely connected with one of the parties.20The best known description of independence was given by Professor Pierre Lalive, who conceives that “Independence implies the courage to displease, the absence of any desire, especially for the arbitrator appointed by a party, to be appointed once as an arbitrator.”212.1.2 ImpartialityUnlike the concept of “independence”, “impartiality” is a much more abstract concept as it involves primarily an interior state of mind which presents special difficulties of measurement.22Impartiality prohibits an arbitrator from any preference or preconceived notions about the issue.23The IBA Rules negatively define the term, stating that:17Alan Redfern & Martin Hunter, supra note 12, 20118Christopher Koch, ‘Standards and Procedures for Disqualifying Arbitrators’, Journal of International Arbitration, (2003) 20, 32619International Bar Association Rules of Ethics for International Arbitrators, Art 3.1:”Dependence arises from relationships between an arbitrator and one of the parties.”20ibid21P. Lalive, Conclusions in The Arbitral Process and the Independence of Arbitrators, ICC Publishing, S,A., Paris, June 199122Alan Redfern & Martin Hunter, supra note 12, 20123Margaret L. Moses, The Principles and Practice of International Commercial Arbitration (Cambridge University Press, 2008) 130“Partiality arises when an arbitrator favours one of the parties, or where he is prejudiced in relation to the subject-matter of the dispute”.24Independence and impartiality are two concepts overlapping each other. They are rarely used individually, but are "usually joined together as a term of art."25In Alan Redfern and Martin Hunter’s opinion, the two elements should be viewed as “the opposite side[s] of the same coin”.26The relationship between them reflects in as Bishop and Reed’s comment: ““An arbitrator who is impartial but not wholly independent may be qualified, while and independent arbitrator who is not impartial must be disqualified. In selecting party-appointed arbitrators in international arbitration, the absolutely inalienable and predominant standard should be impartiality”.27In this sense, independence and impartiality are actually two ways of looking at the same thing.282.1.3 NeutralityIn arbitration, neutrality is often equated with impartiality. It seems difficult to distinguish them at first sight.29But Professor Giorgio Bernini insists that neutrality and impartiality are “intrinsically different”30. In his viewpoint, the neutrality implies “the likelihood that the arbitrator is, and will remain, wholly equidistant in thought and action throughout the arbitral proceedings”.31As the word suggests, "equidistance" emphasizes that the arbitrator is literally equally distant from the parties, and not closer (more partial or biased) to one party than the other.32There is a popular belief that the neutrality of the arbitrator24IBA Rules of Ethics, supra note 19, Article 3.125Alan Redfern & Martin Hunter, supra note 12, 20126ibid27Doak Bishop & Lucy Reed , ‘Practical Guidelines for Interviewing, Selecting and Challenging Party Appointed Arbitrators in International Commercial Arbitration’ Arbitration International (1998)14, 40028Christopher Koch, supra note 18, 32929Jarvin, Sigvard, ‘Appointment of Arbitrators, Arbitration Institute of the Stockholm Chamber of Commerce’, Stockholm Arbitration Report 25, June 2002.30Giorgio Bernini, ‘Cultural Neutrality: A Prerequisite to Arbitral Justice’, Michigan Journal of International Law, (1989) 10, 3931ibid32Rosabel E. Goodman-Everard, ‘Cultural Diversity in International Arbitration-A Challenge for Decision-makers and Decision-Making’, Arbitration International (1990) 7, 156in international arbitration is largely synonymous with nationality.33The requirement for being neutral is particularly essential to party-appointed arbitrators since they are more likely to be empathetic for the party who nominated them due to the common background and cultural identity.34While a neutral arbitrator would not “allow this shared outlook to override his conscience and professional judgement if he believe that the other party has made the better case.”352.2 The Current Regulation of Impartiality, Independence and Neutrality The different comprehensions towards the principle of impartiality, independence and neutrality directly gave birth to the diversity in legislation. Therefore, it is sensible to probe into the details of these statutory requirements and institutional rules.2.2.1 The Requirements for Both Impartiality and IndependenceIt is the mainstream view that the impartiality and independence of arbitrators are equally important since each of them plays an indispensable role in ensuring a fair arbitral proceeding and a just award. This approach is adopted by majority of countries and arbitration institutions, and the most influential one goes to UNITRAL Model Law. Article 12 stipulates that either impartiality or independence could be regarded as an actionable factor to challenge the arbitrator and Article 18 requires equal treatment should be given to the parties.36Seven jurisdictions by reference of UNITRAL Model Law,namely Australia, Canada, Germany, Mexico, the Netherlands, New Zealand and Singapore, have adopted this language in full.37Similar provisions could also be found in other leading international arbitration institutions, such as LCIA38, AAA39, WIPO40, and SCC41. 33Doak Bishop & Lucy Reed, supra note 26, 39534M. Scott Donahey, The Independence and Neutrality of Arbitrators, Journal of International Arbitration (1992) 9, 31735Alan Redfern & Martin Hunter, supra note 12, 20236UNITRAL Model Law. art. 1237Working Group, ‘Background Information on the IBA Guidelines on Conflicts of Interest in International Arbitration’, Business Law International (2004) 5, 44138London Court of International Arbitration Rules art.5.339American Arbitration Association International Arbitration Rules art.7.40World Intellectual Property Organization Arbitration Rules art.22.As for IBA Guideline, the general principle 1 clearly demands that:“Every arbitrator shall be impartial and independent of the parties at the time of accepting an appointment to serve and shall remain so during the entire arbitration proceeding until the final award has been rendered or the proceeding has otherwise finally terminated.”42 Besides the special legislation in arbitration field, the impartiality and independence of arbitrators are also regulated by other statutes. For instance, the article 6 of the European Convention on Human Rights provides that: “Everyone is entitled to a fair and public hearing within a reasonable time by an independent and impartial tribunal.”43 Notwithstanding that the stipulation is not directly applicable to arbitrator, the cardinal principle shrined in it is universally applied, and the court bound by the Convention is subject to the principle in the review of the arbitral award.442.2.2 The Requirements for Mere ImpartialityThis type of approach is well represented in Britain and US. Under the article 24 of English Arbitration Act 1996, the court is empowered to remove an arbitrator when “circumstances exist that give rise to justifiable doubts as to his impartiality.”45The Act drafter excluded the “independence standard” because they worried that the overly strict requirement for arbitrators will result in “endless arguments”. Additionally, the arbitration is consensual and “there may well be situations in which the parties desire their arbitrators to have familiarity with a specific field, rather than being entirely independent.”46For this reason, “lack of independence, unless it gives rise to justifiable doubts about the impartiality of the arbitrator [,] is of no significance”.47This view is supported by the Court of Appeal in Stratford v Football Association Ltd.48Similarly, American Federal Arbitration Act 41Arbitration Rules of the Arbitration Institute of the Stockholm Chamber of Commerce art.1442Council of the International Bar Association, IBA Guidelines on Conflicts of Interest in International Arbitration General Principle 143European Convention on Human Rights and Fundamental Freedoms (“ECHR”) art.6(1)44Emmanual Gaillard and John Savage, Fouchard, Gaillard, Goldman on International Commercial Arbitration (The Hague : Kluwer Law International,2004) 56445Arbitration Act 1996, art.2446Departmental Advisory Committee (‘DAC’) Report on the Arbitration Bill, 1996 para.101-10347ibid48Stretford v Football Association Ltd, [2007] EWCA Civ 238, para 39. In this case, The Court opined that lack of independence is only relevant if it gives rise to such doubts, in which case the arbitrator can be removed for lackcontains “evident partiality” as one of the grounds to vacate an award.49The reason why England and United States endorse the unilateral criterion lies in that, in Anglo-American legal system, there is a major distinction between the rules governing the party-appointed arbitrator and the rules governing the neutral arbitrator. The inclination of former to parties is permitted while the one of latter is strictly prohibited50, which inevitably implies that sometimes the arbitrator is not completely independent.2.2.3 The Requirements for Mere IndependenceIn contrast with UK who relies on the impartiality of the arbitrator only, the ICC Rules made a notable exception by taking only independence as a criterion for absence of bias.51ICC arbitration committee opined that it is hard to offer a satisfactory definition of “impartiality”on account of its subjective nature as compared to the concept of “independence” which could be measured by objective facts with more ease.52However, as Stephen R. Bond pointed out, the exclusion of “impartiality” in the ICC rules “must not be mistakenly understood as an endorsement of the idea that an arbitrator has the right to be biased so long as he or she is independent. Nor must the absence be misperceived as implying that the ICC considers that arbitrators nominated by a party are inherently incapable of being impartial.”53Meanwhile, the Rules also indicates that challenge can be made for “an alleged lack of independence or otherwise.” Here, “impartiality” should be included in this miscellaneous provision.54On the international level, a rticle 14 of Washington Convention 1965 specified arbitrators shall be those “who may be relied upon to exercise independent judgement”.55of impartiality.49Federal Arbitration Act Section 10. § (a) (2)50New York Civil Practice Law & Rules g 7.51 l(b)(1)51International Chamber of Commerce (ICC) Rules of Arbitration Art.7(1) reads as follows: “every arbitrator must be and remain independent of the parties involved in the arbitration”.52Stephen R. Bond, ‘The Selection of ICC Arbitrators and the Requirement of Independence’, Arbitration International 1988(4),30453Stephen R. Bond,‘The International Arbitrator: From the Perspective of the ICC International Court of Arbitration’Northwestern Journal of International Law & Business 1991(12), 1254Michel A. Calvo, ‘The Challenge of the ICC Arbitrators: Theory and Practice’ Journal of International Arbitration 1998(15) 64-6555Convention on the Settlement of Investment Disputes Between States and Nationals of OtherStates(Washington Convention 1965) Art.142.2.4 The Requirements for NeutralityAs mentioned earlier, the assimilation of neutrality and nationality appears to be confirmed in the text of the major arbitral rules.56None of these rules explicitly refer to or require "neutral" tribunals, but most call for some consideration of nationality.57Theoretically, the qualification, experience and integrity of the arbitrator are crucial factors which should count, rather than one’s citizenship. This idea is evidenced in the Model Law, which affirms that:No person shall be precluded by reason of his nationality from acting as an arbitrator, unless agreed by the parties.”58Nevertheless, given the reality of national identification as well as wide suspicion of national favoritism59, additional conditions of nomination are set forth in various international arbitral rules. The UNCITRAL Rules, for example, state that：In making the appointment, the appointing authority shall ……take into account as well the advisability of appointing an arbitrator of a nationality other than the nationalities of the parties.60It is the prevailing practice in today’s international commercial arbitration that the nationality of the arbitrator must differ from those of the parties. This prevalence is advocated by Professor Lalive, who noted that neutral nationality of the arbitrator is necessary, for without it, "an unhealthy atmosphere of doubt and fear is likely to appear."61 B ut some organizational rules raise significant exceptions, e.g.,in "suitable circumstances" (“ICC”)62or "special circumstances such as the need to appoint a person having particular qualifications" ("WIPO")63or “unless the parties who are not of the same56llhyung Lee, ‘Practice and Predicament: The Nationality of The International Arbitrator(With Survey Results)’ Fordham International Law Journal 2008(31),60957ibid58UNCITRAL Model Law supra note 9, Art 11(1)59Ilhyung Lee, supra note 56, 61360UNITRAL Arbitration Rules, Art. 9.161Pierre Lalive, supra note 10, 2662ICC Rules, supra note 51, arts. 9(1), 9(5).63WIPO Arbitration Rules, supra note 40 art. 20(b),nationality as the proposed appointee all agree in writing otherwise." ("LCIA")64These exceptions remind us that party autonomy is the starting point of the arbitration process. Party agreements concerning the national neutrality of the arbitrators must be adhered to, since failure to do so may cause the subsequent award being set aside, or be refused from recognition and enforcement by national courts.65It is also noteworthy that an arbitrator from a neutral country does not guarantee the certainty of his independence or impartiality. Indeed, the appearance is much more convincing and the concrete criteria to assess it will be illuminated below.3.0 Test of Impartiality and Independence of ArbitratorsDespite the global uniformity in terms of the requirements of impartiality and independence for arbitrators, no consensus has been reached with respect to the standards assessing the bias and prejudiced attitude of arbitrator. Meanwhile, however, the lack of a unified criterion contributes to a variety of interpretation. The following section is aimed at investigating and comparing the variation of some fundamental standards among organisations and nations.3.1 The Standard of Arbitrators and the Standard of JudgesThere has been considerable debate over whether it is appropriate to apply the same standard of conduct to arbitrators acting in private arbitrations and to judges acting in their public function. One point holds that an arbitrator should be constrained by more rigorous standards on the question of impartiality than the judiciary, on the basis that ‘his position is even more delicate’ because ‘what he does cannot be corrected’66. In the landmark case Commonwealth Coatings Corp. v. Continental Casualty Co, Justice Black of the Supreme Court of the United States held that if an arbitrator fails to disclose dealings with one of the parties "that might create an impression of possible bias", it might be a ground for vacating64LCIA Rules, supra note 38, art 6.165Ilhyung Lee, supra note 54, 61166Fleming's Trustees v. Henderson and others 1962 SLT 401the award under the "evident partiality" language of the Arbitration Act.67He further explained that the reason for application of a more stringent standard of “appearance of bias” to arbitrators is mainly owing to the varied social pos ition between arbitrators and judges. For judges, they are offered high salaries and supervised by an integral legal system to keep their impartial status. Whereas it is an undisputed fact that arbitrators are more vulnerable to external pressures from the business industry to which they belong since they do not derive all their income from deciding cases.68Suffice to say, the contractual nature of the arbitration process gives parties more bargaining chip. Moreover, arbitrators’ power is often more extensive than those of the judiciary and they have “completely free rein to decide the law as well as the facts and are not subject to appellate review”69. In some circumstances, an arbitrator may even find himself exercising jurisdiction over sovereign states - a situation unlikely to be met by a domestic judge.70It is thus imperative that an arbitrator with such potentially wide powers to be restricted more scrupulously than that of judges.71Similar point was reflected in the English case AT&T v. SCC, in which Lord Woolf held that if there were two standards, he would expect “a lower threshold applied to courts of law” who are “responsible for the provision of public justice” than applies to a private tribunal whose judges “are selected by the parties”.72The opposite view is that the standard of impartiality for arbitrators should be less harsh than the one governing judges. In the case Merit Ins. Co v. Leatherby Ins. Co, Justice Posner proposed that an arbitrator can be challenged only when there is enough evidence to cast “serious doubts” about his impartiality.73His observation was made in the American context where judicial impartiality is prized above expertise. While in arbitration, “No one is forced to arbitrate a commercial dispute unless he has consented by contract to arbitrate.”74Hence, parties choose arbitration means they have voluntarily traded off 67Steven J. Goering, ‘Standard of Impartiality as Applied to Arbitrators by the Federal Courts and Codes of Ethics’, Georgetown Journal of Legal Ethics, 1990 (3), pp. 82468Shivani Singhal, ‘Independence and Impartiality of Arbitrators’ International Arbitration Law Review 2008(11) 126 69Commonwealth Coatings Corp. v. Continental Casualty Co, 393 U.S. 149 (1968)70Gillian Eastwood, ‘A Real Danger of Confusion? The English Law Relating to Bias in Arbitrators’Arbitration International 2001(17) 29071Cook Industries, Inc. v. C. Itoh & Co., 449 F.2d 106 (2d Cir.1971)72AT&T Corp v Saudi Cable Co. [2000] C.L.C. 130973Merit Insurance Company v. Leatherby Insurance Company 714 F 2d 673. (7th Cir. 1983)74ibidimpartiality for expertise. Likewise, this standard is commonly used in German judicial practices, o n the grounds that parties choose their arbitrators, but not their judge.75Party autonomy should be respected by the national jurisdictions.However, both of the two extremes expressed above have been severely criticized. First, the fact that arbitration is a consensual process and that the parties choose their arbitrators in a way that they cannot choose their judges does not logically lead to the conclusion that the tests for bias should be any different.76It would be assertive to generalize a more stringent standard for disqualifying arbitrators on the assumption that parties to an arbitration always prize expertise above other factors. The decision as to whether this tradeoff is required should be left to the parties.77On the other hand, lacking the right to appeal cannot justify a lower threshold because if the arbitral award is wrong on account of bias on the part of the arbitrator, it may be set aside.78Justice Kaufman believed that the standard of "appearance of bias" is too low for the invalidation of an arbitral award, while "actual bias" is rarely possible to provide direct proof. So instead of taking these two unrealistic standards, he critically put forward that "evident partiality" within the meaning of U.S.C. Sec. 1079will be found where a reasonable person would be convinced that an arbitrator was partial to one party of the arbitration.80It can be seen that the middle level threshold of “reasonable suspicion” is effectively the same as that for judges.81This standard was reaffirmed by subsequent cases in United States.82The75Working Group, supra note 37, 44376Gillian Eastwood, supra note 69, 29077Stephanie Smith, ‘Establishing Neutrality in Arbitrations Involving Closely Knit Industries’ World Arbitration and Mediation Report 2001 (12) 23778Shivani Singhal, supra note 67, 12679United States Code Title 9 Section 10 (a) (2): In any of the following cases the United States court in and for the district wherein the award was made may make an order vacating the award upon the application of any party to the arbitration—where there was evident partiality or corruption in the arbitrators, or either of them;80Morelite Orelite Construction Corp. v. New York City District Council Carpenters Benefit Funds 748 F.2d 79 (2d Cir. 1984)81The essential identity of the standards is apparent from the 1974 addition to 28 USC s 455. Subsection (a) provides that ‘any justice, judge, or magistrate of the United States shall disqualify himself in any proceeding in which his impartiality might reasonably be questioned ’.82See also Liteky v United States,510 US 540, 553 (1994) (‘subsection (a) deals with the objective appearance of partiality) (emphasis in the original). Justice Kennedy's concurring opinion in Liteky explained that, ‘for present purposes, it should suffice to say that s 455(a) is triggered by an attitude or state of mind so resistant to fair and dispassionate inquiry as to cause a party, the public, or a reviewing court to have reasonable grounds to question the neutral and objective character of a judge's rulings or findings. I think all would agree that a high threshold is required to satisfy this standard’(at 557). The US judicial standard, then, is ‘reasonable suspicion’; as this is clearly something higher than mere appearance and lower than actual bias, it is also similar to ‘real danger’--as Lord Woolf observed in AT&T , above.。

调制线粒体钙作为阿尔茨海默氏症的药物靶老龄化住宅

Ageing Research Reviews 9 (2010) 447–456Contents lists available at ScienceDirectAgeing ResearchReviewsj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /a rrReviewModulation of mitochondrial calcium as a pharmacological target for Alzheimer’s diseaseClara Hiu-Ling Hung a ,Yuen-Shan Ho a ,Raymond Chuen-Chung Chang a ,b ,c ,∗aLaboratory of Neurodegenerative Diseases,Department of Anatomy,LKS Faculty of Medicine,The University of Hong Kong,Pokfulam,Hong Kong,China bResearch Centre of Heart,Brain,Hormone and Healthy Aging,LKS Faculty of Medicine,The University of Hong Kong,Pokfulam,Hong Kong,China cState Key Laboratory of Brain and Cognitive Sciences,The University of Hong Kong,Pokfulam,Hong Kong,Chinaa r t i c l e i n f o Article history:Received 8February 2010Received in revised form 14May 2010Accepted 19May 2010Keywords:Mitochondria CalciumAlzheimer’s diseaseVoltage dependent anion channel Mitochondrial membrane potentiala b s t r a c tPerturbed neuronal calcium homeostasis is a prominent feature in Alzheimer’s disease (AD).Mito-chondria accumulate calcium ions (Ca 2+)for cellular bioenergetic metabolism and suppression of mitochondrial motility within the cell.Excessive Ca 2+uptake into mitochondria often leads to mitochon-drial membrane permeabilization and induction of apoptosis.Ca 2+is an interesting second messenger which can initiate both cellular life and death pathways in mitochondria.This review critically discusses the potential of manipulating mitochondrial Ca 2+concentrations as a novel therapeutic opportunity for treating AD.This review also highlights the neuroprotective role of a number of currently available agents that modulate different mitochondrial Ca 2+transport pathways.It is reasoned that these mitochondrial Ca 2+modulators are most effective in combination with agents that increase the Ca 2+buffering capacity of mitochondria.Modulation of mitochondrial Ca 2+handling is a potential pharmacological target for future development of AD treatments.© 2010 Elsevier B.V. All rights reserved.1.IntroductionAs the average life span of human population gradually increases,the prevalence of age-related diseases has signiﬁcantly increased.Alzheimer’s disease (AD)is a fatal neurodegenerative disorder,affecting approximately 35.6million people worldwide (Prince and Jackson,2009).AD is the most common form of dementia.The disease is characterized by progressive synaptic dys-function and neuronal loss in various brain regions,especially in the cortex and hippocampus.Severe neurodegeneration in these brain regions results in cognitive,emotion,social and motor impair-ments.With more than a 100years of research,the underlying mechanism of this incurable disease still remains elusive.Per-turbed neuronal calcium (Ca 2+)homeostasis is a common feature in many neurodegenerative diseases including AD,amyotrophic lat-eral sclerosis (ALS),ischemic stroke and Parkinson’s disease (PD)(Mattson and Chan,2003).Increasing lines of evidence support the idea that Ca 2+dysregulation plays a key role in AD pathogenesis∗Corresponding author at:Rm.L1-49,Laboratory Block,Faculty of Medicine Building,Department of Anatomy,LKS Faculty of Medicine,21Sassoon Road,Pok-fulam,Hong Kong SAR,China.Tel.:+852********;fax:+852********.E-mail address:rccchang@hku.hk (R.C.-C.Chang).(Bezprozvanny,2009;Bojarski et al.,2008;LaFerla,2002;Mattson and Chan,2003;Yu et al.,2009).2.Neuronal Ca 2+dysregulation and Alzheimer’s disease Ca 2+signaling is essential for life and death processes includ-ing neuronal excitability,synaptic plasticity,gene transcription and apoptosis (Berridge,1998;Berridge et al.,1998).The Ca 2+dysregulation hypothesis postulates that sustained increase in cytosolic Ca 2+concentrations can lead to neurodegeneration in AD (Khachaturian,1994;Toescu and Verkhratsky,2007).Disturbances in Ca 2+signaling have been found in both sporadic and familial cases of AD (LaFerla,2002).Several age-related perturbations in pathways regulating Ca 2+homeostasis have been reported,sug-gesting a possible linkage between aging and the development of sporadic AD (Bezprozvanny,2009).A small proportion of AD patients (∼5%)suffer from an early-onset familial form that occurs under age of 65(Hardy,2006).The genes involved in familial AD include presenilins (presenilin 1and 2)and amyloid precursor pro-tein (APP)(Hardy and Gwinn-Hardy,1998).Both have been shown to play important roles in Ca 2+signaling (LaFerla,2002).The mech-anisms of how Ca 2+homeostasis is disrupted in AD have been extensively reviewed (Bezprozvanny,2009;Bojarski et al.,2008;LaFerla,2002;Mattson and Chan,2003;Yu et al.,2009).In the fol-1568-1637/$–see front matter © 2010 Elsevier B.V. All rights reserved.doi:10.1016/j.arr.2010.05.003448 C.H.-L.Hung et al./Ageing Research Reviews9 (2010) 447–456lowing sections,we will brieﬂy discuss this issue for readers to understand how Ca2+dyshomeostasis is linked with AD.2.1.APP mutation induces Ca2+inﬂux and elevates cytosolic Ca2+ concentrationsAccumulation of senile plaques and neuroﬁbrillary tangles are two important pathological hallmarks in AD brains.Senile plaques are made of beta-amyloid(A␤)peptides which are derived from APP.Mutations associated with familial AD result in increased pro-duction of the amyloidogenic A␤fragments(Mattson,1997).APP derivatives such as secreted forms of APP(sAPP),A␤-containing fragments,and APP intracellular domain(AICD)have been shown to modulate cellular Ca2+signaling(Leissring et al.,2002;Mattson et al.,1993,1992).A␤aggregates have been found to form cation-selective ion channels in the plasma membrane,resulting in increased cytosolic Ca2+concentrations(Arispe et al.,1993a,b; Kagan et al.,2002).Nevertheless,how A␤-induced membrane pores are related to human AD is still unclear.Oxidative dam-age is another mechanism by which A␤causes disruption in Ca2+ homeostasis and neurotoxicity(Hensley et al.,1994;LaFerla,2002). Accumulation of A␤leads to formation of reactive oxygen species (ROS),which promotes DNA damage,lipid peroxidation,protein carbonylation and nitrosylation.Lipid peroxidation modiﬁes func-tions of membrane transporters and ion channels(Mark et al., 1995),which in turn further elevates basal cytosolic Ca2+concen-trations,forming a vicious cycle(LaFerla,2002;Mattson and Chan, 2003).2.2.Presenilins modulate ER Ca2+signaling and enhance ER Ca2+ releasePresenilins(PS1and PS2)are components of the␥-secretase complex which are involved in the proteolytic cleavage of APP.PS1 and PS2are located in various intracellular compartments such as the endoplasmic reticulum(ER)(Annaert et al.,1999),Golgi apparatus(Annaert et al.,1999),and mitochondria(Ankarcrona and Hultenby,2002).Notably,presenilins are highly enriched in a speciﬁc region where the ER membranes are in close contact with mitochondria namely the ER-mitochondrial-associated mem-branes(MAM)(Area-Gomez et al.,2009).FAD-linked presenilin mutations are believed to alter the activ-ity of␥-secretase such that more A␤are produced,especially the ﬁbrillogenic A␤1–42peptides(Xia et al.,1997).FAD-related mutant presenilins can also affect ER Ca2+handling independent of A␤by exaggerating Ca2+release from the ER in response to agonist stim-ulation.FAD mutant PS1and PS2have been shown to interact with the inositol1,4,5-triphosphate receptor(InsP3R)Ca2+-releasing channels and enhance their gating activity by a gain-of-function effect(Cheung et al.,2010,2008).InsP3Rs are more likely to be in a high-probability burst mode,resulting in enhanced ER Ca2+release (Cheung et al.,2010).However the molecular mechanism of this modulation remains elusive.Depletion of ER Ca2+store triggers Ca2+inﬂux from extracellu-lar space via store-operated Ca2+channels(Putney,1986).This is known as capacitive Ca2+entry(CCE or store-operated Ca2+entry). Stromal interacting molecule1(STIM1)protein acts as Ca2+-sensors on the ER which interacts with Orai1/TRPC channels in the plasma membrane and activates store-operated channels for Ca2+entry (Ong et al.,2007;Zhang et al.,2005).CCE has been shown to be attenuated by presenilin mutants,possibly due to increased Ca2+ in the ER store(Herms et al.,2003;Leissring et al.,2000;Yoo et al.,2000).Moreover,increased levels of STIM1have been found in mouse embryonicﬁbroblasts lacking presenilins,implicating that expression of STIM1may be presenilin-dependent(Bojarski et al., 2009).2.3.Ca2+-dependent tau phosphorylation and dephosphorylationNeuroﬁbrillary tangles formed by hyperphosphorylation of the microtubule-associated protein tau are another hallmark in AD.The phosphorylation state of tau is highly Ca2+-dependent. Tau phosphorylation is regulated by Ca2+-dependent calmodulin-dependent protein kinase II(CaMKII)and calpain(Litersky et al., 1996;Maccioni et al.,2001).Activation of cyclin-dependent pro-tein kinase5(Cdk5)by calpain via p25has been suggested to play a role in tau hyperphosphorylation(Maccioni et al.,2001). On the other hand,calcineurin,a Ca2+/calmodulin-dependent pro-tein phosphatase is involved in tau dephosphorylation(Fleming and Johnson,1995).Tau dephosphorylation was completely atten-uated in rat cerebral-cortical slice pre-treated with the calcineurin inhibitor Cyclosporin A(Fleming and Johnson,1995).Injection of FK506(a calcineurin inhibitor)has been reported to enhance tau phosphorylation at various phosphorylation sites in mouse brain (Luo et al.,2008).On the other hand,calcineurin inhibitors have also been shown to increase phosphorylation of glycogen synthase kinase-3beta(GSK-3␤)at serine-9(Kim et al.,2009).Phosphoryla-tion of GSK-3␤at serine-9inhibits tau phosphorylation by GSK-3␤(Hughes et al.,1993).Hence,both increase and decrease cytosolic Ca2+concentrations contribute to tau phosphorylation,therefore perturbed Ca2+homeostasis may associate with the tau pathology in AD.2.4.Sporadic AD:ApoE4and CALHM1Apolipoprotein E is involved in transporting cholesterol from the blood to the cells.Individuals with the allele for the E4isoform of apolipoprotein E(ApoE4)have an increased risk of sporadic AD (Mahley et al.,2006).ApoE4was found to disrupt Ca2+homeosta-sis by triggering extracellular Ca2+inﬂux and amplifying neuronal Ca2+responses(Hartmann et al.,1994;Tolar et al.,1999).Recent research has identiﬁed polymorphism of a gene called calcium homeostasis modulator1(CALHM1)that may link with sporadic AD.CALHM1encodes for a protein which forms a Ca2+channel on the plasma membrane and controls A␤levels(Dreses-Werringloer et al.,2008).Since then several studies have shown that the P86L polymorphism of CALHM1is associated with AD(Boada et al.,2010; Cui et al.,2010),whilst other studies failed toﬁnd a link between CALHM1and risk of AD(Bertram et al.,2008;Minster et al.,2009; Nacmias et al.,2010;Sleegers et al.,2009).The relevance of CALHM1 in AD remains unclear.2.5.Current“Ca2+-targeted”drugsAs illustrated above,it is clear that Ca2+signaling pathways are highly involved in AD pathogenesis.Several FAD-approved drugs and drugs tested in clinical trials therefore aim to tar-get different Ca2+signaling pathways in order to re-establish the cytosolic Ca2+homeostasis.Memantine(Namenda)is the most common drug for moderate to severe AD.Memantine is a non-competitive N-methyl D-aspartate(NMDA)antagonist.It inhibits Ca2+entry into neurons through the NMDA receptors and therefore reduces excitotoxicity(Bezprozvanny,2009).How-ever,currently it only provides limited beneﬁts for AD patients. Hu et al.(2009)found that speciﬁc antagonists targeting at NMDA receptors containing the GluN2B subunit e.g.ifenprodil and Ro25–6981,might be effective in protecting neurons from A␤-induced inhibition of synaptic plasticity in vivo.EVT-101 (Evotec AG,Hamburg,Germany;/)is a newly developed NMDA receptor subunit2B speciﬁc antagonist. Phase I trial of EVT-101is completed and cognitive performance of patients was improved(NCT00526968).This speciﬁc NMDA receptor antagonist is believed to greatly reduce the chance ofC.H.-L.Hung et al./Ageing Research Reviews9 (2010) 447–456449Fig.1.Life and death pathways of mitochondrial Ca2+accumulation.Left:Under normal conditions,Ca2+inﬂux from extracellular matrix or Ca2+release from the ER causes increase in cytosolic Ca2+concentration([Ca2+]i).Mitochondria rapidly take up cytosolic Ca2+,which is crucial for life processes such as mitochondrial movement,Ca2+ homeostasis and bioenergetic metabolism.Right:When mitochondria are overloaded with Ca2+,mitochondrial permeability transition pores will be triggered to open. Several pro-apoptotic factors will be released to the cytosol,thereby inducing apoptosis.side effects caused by the unspeciﬁc NMDAR antagonist meman-tine.Nimodipine is an isopropyl Ca2+channel blocker which has been shown to improve cognitive performance of dementia patients including AD(Lopez-Arrieta and Birks,2002).MEM-1003(Memory Pharmaceuticals,Montvale,New Jersey,USA; /)is a nimodipine-related neu-ronal L-type Ca2+channel antagonist.Phase IIa clinical trial has recently been completed(NCT00257673),but failed to show sig-niﬁcant improvements in patients(Hareyan,2007).Evidence from NMDA receptor antagonists and Ca2+channel blockers indicates that decreased Ca2+ﬂux into neurons may beneﬁt AD patients.Indeed,classic therapies which aim to compensate the level of acetylcholine in AD patients also cause alteration in Ca2+home-ostasis.FAD-approved acetylcholinesterase(AChE)inhibitors e.g. Donepezil,Galatamine,and Rivastigmine inhibit degradation of acetylcholine and therefore increase acetylcholine concentrations in the brain which is believed to associate with improvement in cognitive functions.In fact,the AChE inhibitors will cause an increase opening of acetylcholine receptors,which are receptor-activated Ca2+channels themselves.The two major classes of FAD-approved AD drugs(NMDA receptor antagonists and AChE inhibitors)apparently will have opposite effects on cytosolic Ca2+ concentration,implying that there is evidence for both increased and decreased cytosolic Ca2+in AD.Dimebon(Latrepirdine)(Medivation Inc.,San Francisco,CA)is an antihistamine drug used in Russia(Bachurin et al.,2001).Recent studies have discovered the novel role of Dimebon as a neuropro-tective agent as well as a cognition-enhancing agent(Bachurin et al.,2001).As an antagonist of NMDAR and Ca2+channels,Dimebon protects neurons by preventing NMDA and Ca2+-induced neurotox-icity(Bachurin et al.,2001).On the other hand,it also increases the level of acetylcholine by inhibiting the AChE(Bachurin et al.,2001). Phase II clinical trial reported that Dimebon is well tolerated and exhibit signiﬁcant improvements in patients with mild to moder-ate AD(Doody et al.,2008).However,a recent Phase III clinical trial failed to show the same promising results(Neale,2010).Additional Phase III clinical trials of Dimebon are still on-going at the moment; therefore the effectiveness of Dimebon in AD remains debatable.Most of the current AD treatments such as AChE inhibitors can provide a one-time elevation of cognitive performance.How-ever,the decline of cognitive ability from this elevated level will occur with the same speed as in non-treated patients.This urges researchers to seek for disease-modifying drugs.3.Mitochondrial Ca2+governs neuronal life and death pathwaysMitochondria are important in maintaining neuronal Ca2+ homeostasis.Normal mitochondrial functions are extremely important for neurons,as neuronal activities such as synaptic transmission and axonal transport require high level of energy. In particular,mitochondrial Ca2+levels are crucial for maintaining cellular functions including bioenergetic metabolism.On the other hand,excessive Ca2+uptake into mitochondria results in rupture of the outer mitochondria membrane,which may then lead to ini-tiation of apoptosis.However,this phenomenon is likely to occur only in vitro.The regulatory systems maintaining the mitochondrial Ca2+homeostasis thus provide an attractive therapeutic target in treating AD.In the following sections we will explain how mito-chondrial Ca2+is involved in life and death pathways in the cell (Fig.1),and how mitochondrial Ca2+is linked to AD.3.1.The cell life pathway:physiological roles of mitochondrialCa2+uptakeCa2+uptake into mitochondria plays a key role in cellular ATP production and mitochondrial motility.Bioenergetic metabolism in mitochondria highly relies upon Ca2+.In the mitochondrial matrix,activity of the metabolic enzymes involved in the Krebs450 C.H.-L.Hung et al./Ageing Research Reviews9 (2010) 447–456cycle(pyruvate,␣-ketoglutarate,and isocitrate dehydrogenases) is all Ca2+-dependent(Rizzuto et al.,2000).Ca2+directly regulates ␣-ketoglutarate and isocitrate dehydrogenases,whilst pyruvate dehydrogenases are activated by Ca2+-dependent phosphatases (Rizzuto et al.,2000).Ca2+concentration in mitochondria therefore determines the rate of ATP synthesis for the cell.Mitochondria are mobile organelles which travel along the axons to regions of increased energy need in the cell,such as synapses(Chang et al.,2006;Hollenbeck and Saxton,2005). Microtubules-dependent mitochondrial motility is regulated by the kinesin1/Miro/Milton complex(Glater et al.,2006;Guo et al., 2005;Stowers et al.,2002).Miro(mitochondrial Rho GTPase)is a mitochondrial outer membrane protein.The activity of Miro is Ca2+-dependent due to the presence of a pair of Ca2+-binding EF hand motifs(Frederick et al.,2004).Milton is a cytoplasmic protein which binds with Miro to form a protein complex that links kinesin-1to mitochondria for anterograde transport(Glater et al.,2006;Guo et al.,2005;Stowers et al.,2002).The Ca2+-binding EF-hand domain of Miro is essential for Ca2+-dependent mitochondrial movement. Elevated Ca2+causes kinesin heavy chain to dissociate with micro-tubules,suppressing mitochondrial motility(Wang and Schwarz, 2009).Ca2+-dependent mitochondrial motility is crucial for dis-tribution of mitochondria in neurons.It recruits mitochondria to cellular regions with the need of ATP supply and Ca2+buffering e.g. activated synapses(Macaskill et al.,2009).In addition,Miro is essential for regulation of mitochondrial morphology.At resting low cytosolic Ca2+levels,Miro facil-itates the formation of elongated mitochondria by inhibiting dynamin-related protein1(Drp-1or dynamin-like protein1,DLP-1)-mediatedﬁssion(Saotome et al.,2008).On the other hand, high cytosolic Ca2+triggers fragmentation and shortening of mito-chondria(Saotome et al.,2008).Miro-mediated redistribution of mitochondria has also been shown to increase their ability to accumulate Ca2+(Saotome et al.,2008).Evidence from the above studies demonstrates that Miro acts as a cytosolic Ca2+-dependent regulator of mitochondrial dynamics.Meanwhile,calcineurin,a Ca2+-dependent phosphatases,has been shown to regulate the translocation of cytosolic Drp-1via dephosphorylation duringﬁs-sion(Cereghetti et al.,2008).Clearly,Ca2+regulates motility,distribution,morphology and functions of mitochondria in physiological conditions.It is there-fore crucial to maintain mitochondrial Ca2+homeostasis for normal cellular functioning.If this homeostasis is disrupted,a death signal can be resulted.3.2.The cell death pathway:mitochondrial Ca2+overload triggers intrinsic apoptosisThe physiological Ca2+signal can switch to a death signal when the Ca2+level is beyond the threshold.Hence,excessive Ca2+ uptake into mitochondria can be lethal to neurons.The intrinsic (mitochondrial)pathway of apoptosis is triggered by intracellu-lar stress,such as Ca2+overload and oxidative stress(Galluzzi et al.,2009).Mitochondria integrate pro-and anti-apoptotic signals and determine the fate of the cell.If death signals predomi-nate,mitochondrial-membrane-permeabilization(MMP)occurs, and large conductance permeability-transition-pores(PTP)opens (Galluzzi et al.,2009).PTP opening allows uncontrolled entry of solutes and water into the mitochondrial matrix by osmotic forces (Galluzzi et al.,2009).This causes mitochondria to swell and leads to rupture of the outer mitochondria membrane,releasing proteins from the intramembrane space e.g.cytochrome c into the cytosol (Galluzzi et al.,2009).MMP results in mitochondrial depolariza-tion,uncoupling of oxidative phosphorylation,overproduction of ROS and release of pro-apoptotic proteins to the cytosol,eventually leading to cell death.When MMP is permanent and numerous mito-chondria are continuously affected,neurons can no longer cope with the stress and apoptosis is initiated(Galluzzi et al.,2009). Physiological mitochondrial Ca2+concentrations do not induce PTP opening,but will work in synergy with pro-apoptotic stim-uli(Rizzuto et al.,2009).The“double hit”hypothesis proposes that apoptotic stimuli have dual targets(Pinton et al.,2008).On one hand,it causes Ca2+release from the ER and subsequent Ca2+uptake by mitochondria.On the other hand,it makes mitochondria more sensitive to potential Ca2+damaging effects(Pinton et al.,2008).The above pathways are summarized in Fig.1.Given the dual roles of mitochondria Ca2+in neurons,we will critically discuss the possibility of modulating Ca2+in mitochondria as a potential pharmacological target for AD in this review.4.Mitochondrial Ca2+handling and ADMitochondrial dysfunction is a prominent feature in AD.A␤has been found in mitochondria of AD brain and transgenic mouse model of AD overexpressing A␤.A␤peptides accumulate in mito-chondria and are associated with oxidative stress,disrupted Ca2+ homeostasis,impaired energy metabolism and induction of apop-tosis(Mattson et al.,2008).Mitochondria from aged cerebellar granular neurons are depolarized and less efﬁcient in handling Ca2+ load(Toescu and Verkhratsky,2007).Cortical mitochondria from 12-month-old mice also show a reduced capacity for Ca2+uptake when challenged with CaCl2pulses,compared to that of6-month-old mice(Du et al.,2008).Mitochondria isolated fromﬁbroblasts of AD patients exhibit reduced Ca2+uptake compared to age-matched control,suggesting that Ca2+buffering ability may be impaired in the mitochondria of ADﬁbroblasts(Kumar et al.,1994).Follow-ing oxidative stress,the increase in Ca2+uptake in mitochondria of ADﬁbroblasts is much greater than that in control,implicat-ing that mitochondria from ADﬁbroblasts have a higher sensitivity towards oxidative stress(Kumar et al.,1994).Mitochondria with over-expression of human APP also show a lower Ca2+capacity compared to non-transgenic mitochondria(Du et al.,2008).A␤1–42 oligomer induces Ca2+overload in mitochondria in both cortical and cerebellar granular neurons(Sanz-Blasco et al.,2008).The increase is limited to a pool of mitochondria close to the sites of Ca2+entry and release(Sanz-Blasco et al.,2008).Ca2+overload in mitochondria causes increased ROS production and impairment of bioenergetic metabolism which eventually leads to cell death. Mutations in presenilins may promote mitochondrial dysfunction by perturbing ER Ca2+handling,which promotes synaptic mito-chondrial Ca2+overload and in turn triggers apoptosis.A recent study has also shown that mutated CALHM1may cause slower kinetics of mitochondrial Ca2+uptake and release,increasing the risk of mitochondrial Ca2+overload(Moreno-Ortega et al.,2010).The importance of mitochondrial Ca2+in apoptosis has been emphasized in neuronal death in AD.However,mitochondrial Ca2+ is also important in earlier stages of the disease.The rupture of mitochondrial membrane caused by Ca2+overload reduces the number of“healthy”mitochondria,and this will affect crucial neu-ronal functions including synaptic transmission and axonal trans-port.This could perhaps account for some of the early symptoms of the disease e.g.memory impairment.In this notion,the main-tenance of mitochondrial Ca2+homeostasis is important for both early and later stages of the disease.In the following paragraphs, we will illustrate different inﬂux and efﬂux pathways regulating the mitochondrial Ca2+homeostasis,and how different agents tar-geting these pathways can provide neuroprotection in AD.5.Mitochondria in neuronal Ca2+signalingCa2+signaling causes transient changes in cytosolic Ca2+con-centration.Mitochondria rapidly take up Ca2+when a physiologicalC.H.-L.Hung et al./Ageing Research Reviews 9 (2010) 447–456451Table 1Current agents showing neuroprotective effect via modulation of mitochondrial Ca 2+concentrations. «(mitochondrial membrane potential);Ca 2+(calcium ions);FCCP [carbonyl cyanide-p-(triﬂuoromethoxy)phenylhydrazone];mAPP (mutant amyloid precursor protein);mPTP (mitochondrial permeability transition pore);NMDA (N-methyl D-aspartate);NSAIDs (non-steroid anti-inﬂammatory drugs),TAB (Tournefolic acid B);VDAC (voltage-dependent anion channel).Agent/Drug Site of action EffectModelNeurotoxicity model ReferenceFCCP DepolarizationReduce Ca 2+uptake Rat cerebellar granule neurons Rat cortical neuronsA ␤1–42oligomer Sanz-Blasco et al.(2008)NSAIDS DepolarizationReduce Ca 2+uptake Rat cerebellar granule neurons A ␤1–42oligomer Sanz-Blasco et al.(2008)Minocycline VDACDepolarizationReduce Ca 2+uptake Rat cerebellar granule neurons NMDAGarcia-Martinez et al.(2010)KB-R7943Na +/Ca 2+exchanger Reduce Ca 2+uptake Rat cerebellar granule neurons Glutamate Storozhevykh et al.(2009)TABUnknown Reduce Ca 2+uptake Rat cortical neurons A ␤25–35Chi et al.(2008)DimebonmPTPInhibit mPTP opening Rat liver mitochondriaA ␤25–35Bachurin et al.(2003)Cyclosporin ACyclophilin DInhibit mPTP opening Increase Ca 2+buffering capacityMouse cortical mitochondriamAPPTrangenic miceDu et al.(2008)stimulus elicits an increase in cytosolic Ca 2+concentrations.This uptake machinery allows mitochondria to act as “Ca 2+buffers”to maintain the normal homeostasis.At the same time,it also provides Ca 2+for various mitochondrial functions.Mitochondrial Ca 2+sig-naling therefore plays an important role in determining the fate of neurons.Mitochondria possess various Ca 2+inﬂux and efﬂux path-ways (Fig.2),which provide attractive targets for manipulation of Ca 2+concentrations within the organelle (Table 1).5.1.Pathways for Ca 2+uptake5.1.1.Voltage-gated anion channel regulates Ca 2+uptake in theouter mitochondrial membraneThe outer mitochondrial membrane (OMM)is relatively per-meable to Ca 2+due to the high conductance voltage dependent anion channel (VDAC)located in this membrane.Over-expression of VDAC has been shown to promote Ca 2+uptake into mitochon-dria (Rapizzi et al.,2002).Closure of VDAC enhances Ca 2+inﬂux into mitochondria,thereby promoting mitochondrial permeabil-ity transition and subsequent cell death (Rizzuto et al.,2009;Rostovtseva et al.,2005;Tan and Colombini,2007).5.1.2.Mitochondrial membrane potential regulates Ca 2+entry via the uniporter in the inner mitochondrial membraneIn the inner mitochondrial membrane (IMM),the mitochon-drial Ca 2+uniporter regulates Ca 2+entry into mitochondria.The uniporter is a highly selective divalent cation channel (Kirichok et al.,2004).The electron transport chain (ETC)in the IMM con-Fig.2.Mitochondrial Ca 2+signaling pathways. «m (mitochondrial membrane potential);[Ca 2+]m (mitochondrial Ca 2+concentration);[Ca 2+]c ,(cytosolic Ca 2+con-centration);H +(hydrogen ions);PTP (mitochondria permeability transition pore);Na +(sodium ions),VDAC (voltage-dependent anion channel);CypD (cyclophilin D);ANT (adenine nucleotide translocase).sists of ﬁve protein complexes for the production of ATP.The ETC maintains an electrochemical gradient of −180mV across the IMM,and is known as the mitochondrial membrane potential ( «m ). «m provides a driving force for Ca 2+to enter the mitochondria via the uniporter.Given that mitochondrial Ca 2+overload can lead to cell death,depolarization of «m (hence reduced driving force for Ca 2+entry)can be a drug target for stopping excessive Ca 2+from entering mitochondria.5.2.Pathways for calcium efﬂux5.2.1.Antiporters and permeability transition pores for mitochondrial calcium sequestrationBesides various Ca 2+uptake systems mentioned,there are also a few pathways for Ca 2+efﬂux.The Na +/Ca 2+and H +/Ca 2+antiporters are two main routes for Ca 2+release from mitochondria.Generally,3Na +and 3H +enter mitochondria via the respective antiporters when a Ca 2+is extruded (Fig.2).Hence,concentrations of Na +and H +can affect Ca 2+concentration in the mitochondria.These efﬂux pathways can become saturated when there is high Ca 2+concentration in the matrix,which can lead to mitochondrial Ca 2+overload (Rizzuto et al.,2009).As mentioned earlier,mitochon-drial Ca 2+overload triggers opening of PTP which locates across the OMM and IMM.The molecular identity of PTP is still uncer-tain,but it is suggested to be a multimeric complex composed of the VDAC,an integral protein called adenine nucleotide translo-case (ANT)on the IMM,and a matrix protein called cyclophilin D (CypD).However,mitochondria lacking VDAC (Szalai et al.,2000)and ANT (Kokoszka et al.,2004)have been shown to undergo Ca 2+-induced PTP opening,implying that the two components may not be prerequisite for MPT (Rizzuto et al.,2009).PTP is a non-selective channel of which operation is dependent on the mitochondrial matrix Ca 2+.High Ca 2+levels in the mitochondrial matrix activate translocation of CypD to the IMM.CypD binds to ANT and inhibits ATP/ADP binding,thereby inducing opening of PTP (Rizzuto et al.,2009).5.3.ER/mitochondria calcium crosstalk is important for efﬁcient mitochondrial calcium signalingMitochondria rapidly take up Ca 2+released from the ER.The proximate juxtaposition between these two organelles ensures efﬁcient Ca 2+transfer (Rizzuto et al.,1993,1998).In fact,the contact between the ER and mitochondria is estimated to be 5–20%of the total mitochondrial surface (Rizzuto et al.,1998).MAM is a region between the ER and mitochondria enriched with enzymes and proteins involved in lipid biosythesis and Ca 2+sig-naling between the organelles (Vance,1990).Indeed,VDAC on the OMM is located in the interface between the ER and mitochon-。

生物碱类植物化学物治疗和预防阿尔茨海默病的研究进展

生物碱类植物化学物治疗和预防阿尔茨海默病的研究进展李宝龙;单毓娟;刘旭;贾博宇;周忠光【摘要】Alzheimer disease (AD) is the most common type of senile dementia, a neurodegenerative disease without effective therapeutic drugs. At present, some phytochemicals with excellent bioactivities in preventing and treating AD have been targeted in the field of new drugs exploitation. This review summarizes the related literatures published recently which mainly show the latest and resegrch progress of a variety of alkaloids such as galanthamine, physostigmine, huperzine, vinca -derived alkaloids, nicotine in the prevention and therapy for AD.%阿尔茨海默病(AD)是最常见的老年痴呆型神经退行性疾病,目前尚无特效药.研究与开发防治阿尔茨海默病的有效植物化学物是当今医药学研究领域的重要课题之一.通过对近年来有代表性的文献进行分析归纳,总结了加兰他敏、毒扁豆碱、石杉碱、长春花属以及烟碱等生物碱类植物化学物治疗和预防阿尔茨海默病的研究进展.【期刊名称】《中医药学报》【年(卷),期】2012(040)003【总页数】3页(P145-147)【关键词】阿尔茨海默病;植物化学物;生物碱【作者】李宝龙;单毓娟;刘旭;贾博宇;周忠光【作者单位】黑龙江中医药大学,黑龙江哈尔滨 150040;哈尔滨工业大学,黑龙江哈尔滨 150090;黑龙江中医药大学,黑龙江哈尔滨 150040;黑龙江中医药大学,黑龙江哈尔滨 150040;黑龙江中医药大学,黑龙江哈尔滨 150040【正文语种】中文【中图分类】R741.05植物化学物(phytochemicals)是植物中存在一类生物活性成分，由种类繁多的化学物质组成。

1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。

The Neurotoxicity of Local Anesthetics on Growing Neurons: A Comparative Study of Lidocaine,Bupivacaine, Mepivacaine,and RopivacaineInas A.M.Radwan,MD,Shigeru Saito,MD,PhD,and Fumio Goto,MD,PhDDepartment of Anesthesiology&Reanimatology,Gunma University School of Medicine,Gunma,JapanLocal anesthetics can be neurotoxic.To test the hypoth-esis that exposure to local anesthetics produces mor-phological changes in growing neurons and to compare this neurotoxic potential between different local anes-thetics,we performed in vitro cell biological experi-ments with isolated dorsal root ganglion neurons from chick embryos.The effects of lidocaine,bupivacaine, mepivacaine,and ropivacaine were examined micro-scopically and quantitatively assessed using the growth cone collapse assay.We observed that all local anesthetics produced growth cone collapse and neurite degeneration.However,they showed significant dif-ferences in the dose response.The IC50values were ap-proximately,10Ϫ2.8M for lidocaine,10Ϫ2.6M for bupiv-acaine,10Ϫ1.6M for mepivacaine,and10Ϫ2.5M for ropivacaine at15min exposure.Some reversibility was observed after replacement of the media.At20h after washout,bupivacaine and ropivacaine showed insig-nificant percentage growth cone collapse in compari-son to their control values whereas those for lidocaine and mepivacaine were significantly higher than the control rger concentrations of the nerve growth factor(NGF)did not improve this reversibility. In conclusion,local anesthetics produced morphologi-cal changes in growing neurons with significantly dif-ferent IC50.The reversibility of these changes differed among the four drugs and was not influenced by the NGF concentration.(Anesth Analg2002;94:319–24)N eurotoxicity is a concern because of reports of neurologic sequelae after spinal and epiduraladministration of local anesthetics(1).Also,lab-oratory experiments suggested that local anesthetics have the potential to be neurotoxic(2,3).Lidocaine may have more potential for neurotoxicity than bu-pivacaine;however,studies about other local anes-thetics such as mepivacaine and ropivacaine are lack-ing(4).Substantial evidence suggests that,in some cases, impairment results from a direct neurotoxic effect of the local anesthetic(2,5,6).The neural trauma and transient ischemia were suggested to be contributing factors in the neurological complications that accom-panied regional anesthesia in clinical settings(7).The precise morphological changes induced by direct ap-plication of local anesthetics to neurons are not yet fully understood.Recently,Saito et al.(8)have showed that tetracaine produced irreversible changes in growing cultured neurons,and the growth cones were the most quickly affected.This report implies that the clinically used local anesthetic,tetracaine, might have significant effects on neuronal extension in developing or regenerating nervous tissue.Because local anesthetics are sometimes applied to sites where peripheral nerves may be growing or regenerating after injury(e.g.,after exposure to chemical injury, mechanical injury,or neurodegenerative disease), their effects on growing neurons should not be ig-nored in clinical practice.In the present study,we have morphologically examined and compared the effects of the local anesthetics;lidocaine,bupiva-caine,mepivacaine,and ropivacaine on growing neurites.To assess these effects quantitatively,we assayed growth cone collapse of cultured chick pe-ripheral neurons.Growth cones play an important role in the development of the nervous system,such as guidance of neurite extension and establishment of neurite cytoarchitecture(9).The growth cone col-lapse assay is the established quantifying method of examining the effects of substances on developing neurites(10).Supported,in part,by Grants-in-Aid10470313and11770834forScientific Research from the Ministry of Education,Science andCulture of Japan.Accepted for publication September26,2001.Address correspondence and reprint requests to Shigeru Saito,MD,PhD,Department of Anesthesiology&Reanimatology,Gunma Uni-versity School of Medicine,3-39-22,Showa-machi,Maebashi,371-8511,Gunma,Japan.Address e-mail to shigerus@showa.gunma-u.ac.jp.©2002by the International Anesthesia Research Society0003-2999/02Anesth Analg2002;94:319–24319MethodsAfter approval by the Institutional Animal Care Com-mittee,dorsal root ganglia(DRG)were dissected fromlumbar paravertebral region of chick embryos at theirseventh or eighth embryonal day.The tissues wereplated to laminin-coated coverslips and cultured inF-12medium supplemented as in Bottenstein et al.’smethod(11)containing100␮g/mL bovine pituitary extract,2mM glutamine,100U/mL penicillin,100␮g/mL streptomycin,and20ng/mL mouse7S nerve growth factor(NGF).Cultures were maintained at37°C and at5%carbon dioxide.The growth coneswere microscopically examined at least1h before eachexperiment to check for the viability of the culture.Lidocaine and bupivacaine were purchased fromSigma Co.Ltd.(St Louis,MO).Mepivacaine was pur-chased from US Pharmacopeia(Rockville,MD).Ropi-vacaine was obtained from AstraZeneca(London,UK).The local anesthetics were prepared in pre-warmed fresh culture media at concentrations100times those to be obtained in the media.The volume ofthe added local anesthetic solution was1/100of thetotal volume of the culture media to obtain final con-centrations of10Ϫ4,10Ϫ3,10Ϫ2.3,10Ϫ2,and10Ϫ1.3M ofeach of the local anesthetics for the dose responseexperiments.The local anesthetic solution was gentlyadded to culture media of the DRG after20h incultures.The pH of the culture media was measuredusing stat profile5and was not changed after theaddition of the local anesthetic in each experiment.The osmolality of all solutions was measured with avapor pressure osmometer;it was maintained withinan acceptable range.A negative control was includedin every experiment where no local anesthetic wasadded to the culture media to detect any time effectduring the experiments.The cultured neurons wereexamined for the dose responses at15,30,and60minafter the addition of the local anesthetics.In the exper-iment in which the effect of washout was examined,the tissues were kept in the incubator for60min afterthe addition of the drugs,and then the media weregently replaced twice with the fresh prewarmed me-dia that was free from any local anesthetic drug.In anexperiment to detect if the application of a largerconcentration of NGF will affect the results of wash-out,fresh media with100ng/mL NGF was used asthe replacement mediaAfter the exchange of the media,the tissues wereincubated for further1,2,and20h.The tissues werefixed with4%paraformaldhyde in phosphate-buffered saline pH7.4containing10%sucrose as de-scribed previously(12),and viewed with a40ϫphaseobjective using a phase-contrast microscope.Growthcones at the periphery of the explants were scored forthe growth cone collapse assay providing that theywere not in contact or close proximity to the other growth cones or neurite.Fifty to100growth coneswere viewed on a coverslip for scoring and thosewithout filopodia or lamellipodia were counted ascollapsed(10).Data are presented as mean and sd of six indepen-dent measurements.IC50values in the growth conecollapse assays were calculated with the conventionalHill equation,Yϭ100ϫX/(XϩIC50),using a curvefitting software,Origin 6.0J(Microcal Software,Northampton,MA).As Yϭthe percentage of growthcone collapse induced by the local anesthetic drug andXϭthe corresponding concentration of that drug.One-way analysis of variance for repeated mea-surements was used to determine statistically signifi-cant differences between the curves of growth conecollapse.Each result of the growth cone collapse as-says was statistically analyzed by two-way analysis ofvariance with the Scheffe’s method using StatView5.0(SAS Institute,Cary,NC).ResultsCollapse of filopodia and lamellipodia of the DRG wasobserved after their exposure to local anesthetics fol-lowed by narrowing of the neurite shafts that werefinally destroyed.All local anesthetics induced dose-dependent growth cone collapse.However,the doseresponse was significantly among between the fourlocal anesthetics both at15and60min after exposure(Fig.1).The IC50values for the growth cone collapse activitywere approximately10Ϫ2.8M for lidocaine,10Ϫ2.6Mfor bupivacaine,10Ϫ1.6M for mepivacaine,and10Ϫ2.5M for ropivacaine at15min exposure.At30min afterexposure,the approximate IC50values were10Ϫ3.8Mfor lidocaine,10Ϫ2.6M for bupivacaine,10Ϫ2M formepivacaine,and10Ϫ2.9M for ropivacaine.The IC50values at60min were,10Ϫ3.1M for lidocaine,10Ϫ2.7Mfor bupivacaine,10Ϫ2.3M for mepivacaine,and10Ϫ3Mfor ropivacaine(Fig.2).The time course trends ofgrowth cone collapse showed no statistically signifi-cant differences among the four local anesthetics.The effects of washout were examined after theapplication of1mM lidocaine,3mM bupivacaine,20mM mepivacaine,and4mM ropivacaine.The per-centage growth cone collapse was reduced to24%Ϯ11.4%for lidocaine,43%Ϯ17.7%for bupivacaine,25%Ϯ13.8%for mepivacaine,and11.3%Ϯ6.3%for ropi-vacaine after1h of the washout.Two hours afterwashout,the percentage growth cone collapse wasreduced further except for the lidocaine-exposedDRG.The percentage of growth cone collapse at20hafter washout was94%Ϯ4.2%for lidocaine,23.3%Ϯ16.4%for bupivacaine,60%Ϯ20%for mepivacaine,and21.3%Ϯ6.3%for ropivacaine with statisticallysignificant differences between both lidocaine andmepivacaine and the control values(Fig.3).320ANESTHETIC PHARMACOLOGY RADWAN ET AL.ANESTH ANALG LOCAL ANESTHETICS NEUROTOXICITY2002;94:319–24Increasing the concentration of NGF in the culture media after the washout did not improve the revers-ibility of growth cone collapse.There were no statis-tically significant differences between the percentage growth cone collapse after the washout using the me-dia with 100ng/mL NGF and the corresponding val-ues with the 20ng/mL NGF-containing media,except at 2h after washout of lidocaine.(P Ͻ0.05)(Table 1).DiscussionThe growth cone,a highly motile structure at the end of the growing axons and dendrites,has a crucial role in neurological development.The direction and pat-tern of neurite growth is determined by the growth cone (13).Growth cones continuously explore their environment with special receptor molecules (14,15).Motile growth cones normally have a distinctive spreading morphology that support axonal extension and this morphology changes dramatically when they are confronted with repulsive molecules on the post-cell surface (12).There are several growth cone-collapsing factors naturally expressed in some areas of the developing nervous system (12).They are thought to be serving as repellent guidance cues,which pro-hibit neurites from extending into an inappropriate region (14).However,a general destruction of growth cones in growing or regenerating nervous tissues byexternally applied substances could lead to the distur-bance of the normal establishment of cytoarchitecture in the developing nervous system (16,17).In this study,we examined the growth cone collapsing activ-ity of four local anesthetics at concentrations up to 10Ϫ1.3M.All had a significant collapsing effect on the growth cones.However,the IC 50determined by the growth cone collapse assay was highest for mepiva-caine and lowest for lidocaine.There was no statisti-cally significant difference between the IC 50of bupiv-acaine and ropivacaine.This implies that lidocaine has a more intense potential neurotoxic effect on the de-veloping or regenerating primary cultured neurons.In a previous study,we demonstrated that tetracaine has a growth cone collapsing activity with logarithmic IC 50of Ϫ2.9Ϯ0.3at 60min exposure (8).Thus we suggest that tetracaine has a less growth cone collaps-ing effect than lidocaine (IC 5010Ϫ3.1M at 60min exposure).In a previous histopathological study,Kanai et al.(18)demonstrated that 80mM (2.17%)lidocaine in-duced neuronal damage in rat sciatic nerve.Electro-physiological studies have used desheathed periph-eral nerve models to assess electrophysiologic neurotoxicity of clinically relevant concentrations of some local anesthetics.These studies showed that 5%(184.5mM)lidocaine causes irreversible conduction block,whereas 1.5%(55.4mM)lidocaine and 0.75%(23.1mM)bupivacaine do not (19–21).NostructuralFigure 1.Dose response relations of local anesthetics-induced growth cone collapse.Percentage growth cone collapse assayed at 15min exposure (A),and 60min exposure (B).L.A.ϭlocal anesthetic;a ϭsignificantly different from the corresponding values of bupivacaine,mepivacaine (P Ͻ0.01);b ϭsignificantly different from the corresponding values of bupivacaine,mepivacaine,and ropivacaine (P Ͻ0.01);c ϭsignificantly different from the corresponding values of ropivacaine and lidocaine (P Ͻ0.01);d ϭsignificantly different from the corresponding values of lidocaine,mepivacaine,and ropivacaine (P Ͻ0.05,P Ͻ0.01,P Ͻ0.05respectively);e ϭsignificantly different from the corresponding values of lidocaine,bupivacaine,and ropivacaine (P Ͻ0.01).ANESTH ANALG ANESTHETIC PHARMACOLOGY RADWAN ET AL.3212002;94:319–24LOCAL ANESTHETICS NEUROTOXICITYnerve damage was detected after intrafascicular injec-tion of 0.5%(15.4mM)bupivacaine in peripheral nerves of neonatal and juvenile rats (22).However,1.9%(58.5mM)bupivacaine induced significant his-tologic damage after intrathecal infusion in rats (23).It was difficult to compare these results,as the exposure methods were completely different from the present study.Gold et al.(24)showed that the application of lidocaine to DRG neurons isolated from adult rat causes neuronal death at concentrations larger than 10mM.Thus,the potential neurotoxic effects observed in this study might be unique to growing neurons.Local anesthetics can be neurotoxic,particularly in concentrations and doses larger than those used clin-ically (4).In the present study,we observed that four of the commonly used local anesthetics induced growth cone collapse at concentrations smaller than the clinically prepared concentrations.Lidocaine caused more exten-sive nerve damage than bupivacaine and mepivacaine in previous studies (3).In histopathologic,electrophysi-ologic,behavioral,and neuronal cell models,lidocaineseems to have a greater potential for neurotoxicity than bupivacaine at clinically relevant concentrations (4).These results are comparable to our results in respect to the comparative toxicity of local anesthetics.Our observations suggest that local anesthetic-induced toxicity results from direct action of the drug.The pH of the culture media was not changed with the application of local anesthetics.Also,osmolality was maintained within an acceptable range.Sodium chlo-ride,sodium salicylate,and sodium sulfate induced no significant growth cone collapse at concentrations up to 10Ϫ1M in a previous study (25).Other histolog-ical studies support the suggestion that local anesthet-ics produce direct neurological damage (3,4).Increase in intracellular Ca 2ϩions (24),and irreversible loss of membrane potential,which implies membrane dis-ruption (18,20),have been reported as underlying mechanisms of lidocaine-induced toxicity and irre-versible loss of membranepotential.Figure 2.The IC 50values of different local anesthetics at 15,30,and 60min exposure.L.A.ϭlocal anesthetic;a ϭsignificantly different from the corresponding values of lidocaine,bupivacaine,and ropi-vacaine (P Ͻ0.01);b ϭsignificantly different from the correspond-ing values of bupivacaine,mepivacaine,and ropivacaine (P Ͻ0.01);c ϭsignificantly different from the corresponding values of bupiv-acaine and mepivacaine (P Ͻ0.05,P Ͻ0.01respectively);d ϭsignificantly different from the corresponding values of lidocaine and ropivacaine (P Ͻ0.01).Figure 3.Growth cone collapse after the washout of local anesthet-ics.Pre-exposure ϭthe time point immediately before application of local anesthetics;Pre-wash ϭthe time point immediately before washing out the local anesthetics-containing media (1h after expo-sure);a ϭsignificantly different from the corresponding value of the four local anesthetic drugs (P Ͻ0.01);b ϭsignificantly different from the corresponding control value and that of ropivacaine (P Ͻ0.05);c ϭsignificantly different from the corresponding values of lidocaine and bupivacaine (P Ͻ0.05);d ϭsignificantly different from the corresponding values of control cells and the other three drugs (P Ͻ0.01).322ANESTHETIC PHARMACOLOGY RADWAN ET AL.ANESTH ANALGLOCAL ANESTHETICS NEUROTOXICITY 2002;94:319–24By washing out the local anesthetics-containing me-dia after one-hour exposure,some reversibility of growth cone collapse was observed.However,when the assay was performed 20hours after the washout,the percentage of growth cone collapse was signifi-cantly larger for lidocaine and mepivacaine than the control values (Fig.3).However,the growth cone collapse induced by bupivacaine and ropivacaine was significantly attenuated at 20hours after washout.Perhaps,the neurotoxic effects of bupivacaine and ropivacaine are more reversible compared with the other local anesthetics.Although the results of these washout experiments could not be directly applied in clinical settings,the issue that the neurotoxic effects induced by bupivacaine and ropivacaine were more reversible in vitro compared with the other local anes-thetics should be considered.However,it is a remark-able fact that the growth cone collapse continued after removal of local anesthetics from the culture media and the number of intact growth cones did not com-pletely return to the control values for any of the local anesthetics.It is suggested that the cellular processes involved in local anesthetic induced neuronal toxicity are initiated by exposure and proceed further even after stoppage of this exposure.Although the mecha-nism is not completely understood,the increase in intracellular Ca 2ϩions as short as 5min may be suf-ficient to induce delayed neuronal death (26).The washout effects were studied within 48hours of plat-ing (20hours after the washout)to avoid contact of DRG with each other and the possibility of direct interactions among the cells.If the effects demonstrated in this study occur in vivo ,application of local anesthetics may interfere with the growth and regeneration of neuronal tissue.Thus,the potential risk of using local anesthetics in very young children should be considered.In conclusion,local anesthetics induced morpholog-ical changes in growing neurons,impairing their growth in vitro .There are significant differences in thisneurotoxic potential among local anesthetics.Also,different degrees of reversibility were observed after replacement of culture media.Although the results of this in vitro study could not be directly applied in vivo ,the detrimental effects of local anesthetics to growing or regenerating neurons should be considered.References1.Brown DL.Spinal,epidural,and caudal anesthesia.In:Miller R,eds.Anesthesia.Philadelphia:Churchill Livingstone,2000:1491–519.2.Drasner K,Sakura S,Chan VW,et al.Persistent sacral sensory deficit induced by intrathecal local anesthetic infusion in rat.Anesthesiology 1994;80:847–52.3.Selander D.Neurotoxicity of local anesthetics:animal data.Reg Anesth 1993;18:461–8.4.Hodgson PS,Neal JM,Pllock JE,Liu SS.The neurotoxicity of drugs given intrathecally.Anesth Analg 1999;88:797–809.5.Rigler ML,Drasner K.Distribution of catheter-injected local anesthetic in a model of the subarachnoid space.Anesthesiology 1991;75:684–92.6.Ross BK,Coda B,Heath CH.Local anesthetic distribution in a spinal model:a possible mechanism of neurologic injury after continuous spinal anesthesia.Reg Anesth 1992;17:69–77.7.Myers RR,Heckman HM.Effects of local anesthesia on nerve blood flow:studies using lidocaine with and without epineph-rine.Anesthesiology 1989;71:757–62.8.Saito S,Radwan I,Obata H,et al.Direct neurotoxicity of tetra-caine on growth cone and neurites of growing neurons in vitro .Anesthesiology 2001;95:726–33.9.Letourneau PC,Kater SB,Macagno ER.The nerve growth cone.New York:Raven Press,1992.10.Raper JA,Kapfhammer JP.The enrichment of a neuronalgrowth cone collapsing activity from embryonic chick brain.Neuron 1990;4:21–9.11.Bottenstien JE,Skaper Varon SS,Sato GH.Selective survival ofneurons from chick embryo sensory ganglionic dissociates uti-lizing serum free supplemented medium.J Exp Cell Res 1980;125:183–90.12.Luo Y,Raible D,Raper JA.Collapsin:a protein in brain thatinduces the collapse and paralysis of neuronal growth cones.Cell 1993;75:217–27.13.Vale RD,Banker G,Hall ZW.The neuronal cytoskeleton.In:Hall ZW,ed.An introduction to molecular neurobiology.Sunderland:Siauer Associates,1992:247–80.14.Keynes R,Cook GMW.Axon guidance molecules.Cell 1995;83:161–9.Table 1.Growth Cone Collapse Percentage After the Washout of Local Anesthetics-Containing MediaLocal anesthetic NGF concentration(ng/mL)Growth cone collapse %Prewash 1h 2h 20h Control 20 5.3Ϯ1.7 4.5Ϯ1.9 5.5Ϯ1.37.0Ϯ0.8100 5.3Ϯ1.7 4.5Ϯ1.9 5.5Ϯ1.37.0Ϯ0.8Lidocaine 1mM 2098.0Ϯ4.524.0Ϯ11.434.0Ϯ11.494.0Ϯ4.210097.5Ϯ5.012.5Ϯ5.020.0Ϯ0.0*87.5Ϯ18.9Bupivacaine 3mM 2087.5Ϯ10.943.0Ϯ17.733.0Ϯ20.623.0Ϯ16.410087.5Ϯ10.934.0Ϯ17.828.0Ϯ15.524.0Ϯ15.8Mepivacaine 20mM 20100.0Ϯ0.025.0Ϯ13.812.5Ϯ6.160.0Ϯ20.0100100.0Ϯ0.022.5Ϯ5.012.5Ϯ5.045.0Ϯ17.3Ropivacaine 4mM2093.8Ϯ7.511.3Ϯ6.3 2.5Ϯ2.921.3Ϯ6.310093.8Ϯ7.511.3Ϯ6.35.0Ϯ4.125.0Ϯ5.8Data expressed as mean Ϯsd .NGF concentration ϭconcentration of nerve growth factor in the culture media;Prewash ϭbefore washout.*Significantly lower than the corresponding value with 20ng/mL nerve growth factor.ANESTH ANALG ANESTHETIC PHARMACOLOGY RADWAN ET AL.3232002;94:319–24LOCAL ANESTHETICS NEUROTOXICITY15.Saito S,Komiya Y,Igarashi M.Muscarinic acetylcholine recep-tors are expressed and enriched in growth cone membranes isolated from fetal and neonatal rat forebrain:pharmacological demonstration and characterization.Neurosci 1991;45:735–45.16.Fawcette FW.Growth cone collapse:too much of a good thing?Trends Neurosci 1993;16:165–7.17.Johnson AR.Contact inhibition in the failure of mammalianCNS axonal regeneration.Bioassays 1993;15:807–13.18.Kanai Y,Katsuki H,Takasaki M.Lidocaine disrupts neuronalmembrane of rat sciatic nerve in vitro .Anesth Analg 2000;91:944–8.19.Baiton C,Strichartz G.Concentration dependence of lidocaine-induced irreversible conduction loss in frog nerve.Anesthesiol-ogy 1994;81:657–67.20.Kanai T,Katsuki H,Takasaki M.Graded,irreversible changes incrayfish giant axon as manifestations of lidocaine neurotoxicity in vitro .Anesth Analg 1998;86:569–73.mbert L,Lambert D,Strichartz G.Irreversible conductionblock in isolated nerve by high concentrations of local anesthet-ics.Anesthesiology 1994;80:1082–93.22.Hertl MC,Hagberg PK,Hunter DA,et al.Intrafascicular injec-tion of ammonium sulphate and bupivacaine in peripheral nerves of neonatal and juvenile rats.Reg Anesth Pain Med 1998;2:152–8.23.Sakura S,Bollen AW,Ciriales R,Drasner K.Local anestheticneurotoxicity does not result from blockade of voltage-gated sodium channels.Anesth Analg 1995;81:338–46.24.Gold MS,Reichling DB,Hampl KF,et al.Lidocaine toxicity inprimary afferent neurons from the rat.J Pharmacol Exp Ther 1998;285:413–21.25.Saito S.Cholinesterase inhibitors induce growth cone collapseand inhibit neurite extension in primary cultured chick neurons.Neurotoxicol Taratol 1998;20:411–9.26.Randall RD,Thayer SA.Glutamate –induced calcium transienttriggers delayed calcium overload and neurotoxicity in rat hip-pocampal neurons.J Neurosci 1992;12:1882–95.Attention Authors!Submit Your Papers OnlineYou can now have your paper processed and reviewed faster by sending it to us through our new,web-based Rapid Review System.Submitting your manuscript online will mean that the time and expense of sending papers through the mail can be eliminated.Moreover,because our reviewers will also be working online,the entire review process will be significantly faster.You can submit manuscripts electronically via .There are links to this site from the Anesthesia &Analgesia website (),and the IARS website ().To find out more about Rapid Review,go to and click on “About Rapid Review.”324ANESTHETIC PHARMACOLOGY RADWAN ET AL.ANESTH ANALGLOCAL ANESTHETICS NEUROTOXICITY 2002;94:319–24。