小胶质细胞与脑缺血

目前许多研究均支持免疫性炎症反应参与了缺血性中风后的脑损伤。脑缺血后数小时，受损脑区域的炎症反应开始启动，持续数天，使脑缺血所致的迟发性脑损伤加重、神经细胞的生物学功能预后更差，而中枢神经系统（CNS）最主要的免疫效应细胞小胶质细胞则是免疫性炎症反应的重要角色，尤其在半月带，小胶质细胞的活化异常活跃，活化的小胶质细胞与白细胞一样，会释放和分泌大量的前炎症因子、酶和神经营养因子，因此小胶质细胞在脑缺血损伤中的作用逐渐受到关注。深入研究小胶质细胞在脑缺血过程中的作用，将为临床治疗脑缺血提供新的途径。现将小胶质细胞在脑缺血病理过程中的功能、来源及免疫反应综述如下。     

小胶质细胞介导缺血性卒中后炎症的机制研究进展

小胶质细胞是中枢神经系统固有免疫细胞,在维持脑组织局部微环境稳定中发挥重要作用,是介导缺血性卒中后炎症反应的主要细胞,过度激活会加重脑组织炎症损伤,抑制炎症反应是潜在的卒中治疗手段。然而小胶质细胞亦可发挥脑保护作用,抑制不当会干扰其保护作用。本文对其在缺血性卒中后的损伤和保护作用进行综述,阐明调控小胶质细胞活化状态是缺血性卒中有效的治疗方法。     

小胶质细胞在中枢神经系统创伤后的双重作用及调控机制

小胶质细胞是中枢神经系统的固有免疫细胞,在脑或脊髓创伤后的神经炎症反应中起关键作用。神经系统损伤后小胶质细胞可提供神经保护因子,清除细胞碎片并调控神经修补过程。而另一方面,小胶质细胞会产生高水平的促炎及细胞毒性介质从而阻碍CNS修复,促使神经元失能及细胞死亡。小胶质细胞的双重特性可能与其损伤后的表型及功能反应有关。本综述探讨近年来有关脑和脊髓损伤后小胶质细胞活化表型的研究,以及小胶质细胞在神经元、血管、少突胶质细胞生长及再生中的可能发挥的作用。并简述已知的调控表型转换的分子机制,着重探讨可以影响小胶质细胞活化状态的治疗途径。了解小胶质细胞表型调控机制有助于我们增加神经系统损伤恢复的知识,并提供新的治疗策略。     

聚腺苷二磷酸核糖聚合酶-1对脑缺血后神经血管单元的调控

<正>缺血性脑血管病是临床最常见的脑血管疾病,其发病率、致残率和死亡率均较高,已经成为中国城乡居民死亡的首位原因。脑缺血后不仅损害神经元,而且造成包括神经元在内的血-脑屏障、小胶质细胞以及细胞外基质等组织即神经血管单元损伤。临床上脑缺血后单一的神经元保护已不能起到脑保护作用,因此近年来脑保护已从保护神经元转变为神经血管单元的保护。脑缺血后神经血管单元的损伤机制比较复杂,包括能量代谢障碍、自由基生成、炎症反应、钙离子超载等,均能激活大量的转录因子,调控基因表达。研究[1]显示,聚腺苷二磷酸核糖聚合酶-1(PARP-1)是其中重要的转录调控因子之一,能被受损DNA诱导激活,过度激活     

神经血管单元缺血后急性炎症反应的损伤机制

神经血管单元是由神经元、星型胶质细胞、血管内皮细胞、细胞外基质、周细胞、小胶质细胞等组成的一个概念性结构。炎症反应与神经血管单元的缺血损伤密切相关。本文以神经血管单元为框架,从炎性细胞、粘附分子、细胞因子、基质金属蛋白酶等方面综述脑缺血后急性炎症反应的损伤机制。     

针刺对MCAO大鼠脑组织小胶质细胞活化及炎症介质含量的影响

目的研究针刺对MCAO大鼠脑组织小胶质细胞活化及TNF-α、IL-1β、IL-6含量的影响。方法建立MCAO大鼠模型,分别针刺内关、曲池后进行神经体征评分,HE染色检测神经元坏死率,ELISA法检测脑组织炎症介质含量,IBA1免疫荧光染色检测小胶质细胞活化。结果与假手术对照组相比,模型对照组大鼠神经体征评分、脑海马神经元坏死率、脑组织TNF-α、IL-1β、IL-6含量、IBA1表达均明显升高(P<0.01);与模型对照组相比,内关组、曲池组神经体征评分、脑海马神经元坏死率、IL-1含量、IBA1表达明显降低,曲池组TNF-α、IL-6含量明显降低(P<0.05)。结论针刺内关、曲池能改善MCAO大鼠的神经功能损伤,抑制小胶质细胞活化,降低炎症介质含量,提示针刺可能通过影响小胶质细胞活化从而调控脑缺血继发的炎症反应。     

神经血管单元的缺血与炎症

神经血管单元是由神经元、星型胶质细胞、血管内皮细胞、细胞外基质、周细胞及其他支持细胞如小胶质细胞等组成的一个概念性结构.炎症反应与神经血管单元的缺血损伤密切相关.本文以神经血管单元为框架综述脑缺血和炎症的关系.     

调节性T细胞缓解帕金森病中多巴胺神经元炎性损伤

免疫炎症可能是引起帕金森病病理机制级联反应最终导致多巴胺神经元变性缺失的主要因素,黑质纹状体多巴胺神经元变性与小胶质细胞激活和T淋巴细胞浸润相关。调节性T细胞可调控小胶质细胞的激活反应,缓解Th17细胞介导的神经炎症。因此,针对调节性T细胞在其天然免疫和适应性免疫中的相互作用,通过硝基化α-突触核蛋白疫苗、格拉默醋酸盐和骨髓间充质干细胞等方法调控调节性T细胞的数量和功能,清除积聚的错误折叠蛋白,可为帕金森病神经保护治疗提供新的策略。     

黑质小胶质细胞主要组织相容性复合物Ⅱ的表达与帕金森病发生和进展的关系

近年来诸多证据显示,中枢神经统的免疫异常和炎症反应参与了黑质多巴胺能神经元的变性坏死。小胶质细胞的激活是脑内炎症反应的主要标志,小胶质细胞主要组织相容性复合物Ⅱ(MHCⅡ)的表达是小胶质细胞活化的标志。尽管人脑中的小胶质细胞并不持续表达MHCⅡ类分子,但随着年老以及在中枢神经系统出现病变的情况下(包括神经变性),它们的表达确是明显上调的。研究发现,在PD病人和PD动物模型的中脑黑质均可发现大量MHCⅡ阳性的小胶质细胞,MHCⅡ类分子在小胶质细胞将外源性抗原呈递给CD4+Th细胞的过程中起重要作用。在6-羟多巴胺(6-OHDA)、脂多糖(LPS)大鼠模型的观察发现,促红细胞生成素、地塞米松等能明显降低MHCⅡ的表达和小胶质细胞的活化,从而减轻动物模型的临床症状。鉴于MHCⅡ抗原启动的免疫反应在PD的发病过程中有促进慢性神经变性进展的作用,因此,抑制小胶质细胞活性和MHCⅡ表达对控制PD进展可能有重要的治疗上的意义。     

外周炎症性疼痛刺激诱发中枢神经系统小胶质细胞增殖活化

目的 观察外周疼痛刺激后,中枢神经系统小胶质细胞形态和功能特征的变化,方法 采用福尔马林疼痛动物模型,刺激后2、4、8h,1,3d,1,2及4周后处死,制成腰脊髓和脑干切片。小胶质细胞特异表达补体C3受体（单克隆抗体OX－42）,活化型小胶质细胞表达Ⅱ类主要组织相容性复合物Ia(单克隆抗体OX－6）,定性和定量的免疫组化方法显示中枢小胶质细胞及疼痛刺激下形态的转化。结果 福尔马林刺激侧腰脊髓后角和脑干薄束核内小胶质细胞的增殖活化,注射后1d开始出现,3d后明显,1周达到高峰,2周后增殖活化反应开始消退。本研究增殖活化的小胶质细胞表现为激活型,而非活化型或吞噬型。结论 福尔马林注射引起的疼痛刺激或外周炎症反应可能诱发中枢小胶质细胞增殖活化。小胶质细胞的增殖活化可能是慢性疼痛长期持续的原因之一。     

Epilepsy and anomalies of neuronal migration: MRI and clinical aspects

Neuronal migration disorders are the result of disturbed brain development. In such disorders, neurons are abnormally located. In diagnosing these conditions, magnetic resonance imaging is superior to any other imaging technique. This enables us to improve our knowledge of the clinical correlates of neuronal migration. With reference to migrational disorder, a retrospective study of all 303 patients with epileptic seizures referred for magnetic resonance imaging during a 3-year period was performed, 13 patients (aged 12-41, mean age 27) were identified. They represent 4.3% of the entire study group. Of the patients with known epilepsy, 6.7% and of the mentally retarded, 13.7% had migrational disorders. Four patients had schizencephaly as the dominant finding, one was classified as hemimegalencephaly, 2 had isolated heterotopias, and 6 had localized pachy- and/or poly-microgyria. The clinical pictures are complex. Ectopias of grey matter are recognised foci of epilepsy, but from an epileptological and a clinical viewpoint little attention has been given to these disorders. The present study shows that malmigration is not rare in epilepsy patients, especially not in the mentally retarded.     

Hepatic Considerations in the Use of Antiepileptic Drugs

Summary: Virtually all of the major antiepileptic drugs (AEDs) can cause hepatotoxicity, although fatal hepatic reactions are rare. The mechanisms, incidences, and risk profiles for such reactions differ from drug to drug. With carbamazepine and phenytoin, hepatotoxicity may be due to drug hypersensitivity. Although the profiles of patients at risk have not been well-defined for these two antiepileptic drugs, it would appear from reports in the literature that older adolescents and adults are at higher risk than children of developing serious or fatal hepatotoxicity. Once hepatotoxicity develops, mortality rates are 10–38% with phenytoin and 25% for carbamazepine. The risk profile for valproate fatal hepatotoxicity has been more clearly defined. Those at primary risk of fatal hepatic dysfunction are children under the age of 2 years who are receiving multiple anticonvulsants and also have significant medical problems in addition to severe epilepsy. The risk is considerably lower for patients over the age of 2 years on valproate monotherapy. In contrast to the risk profile with other AEDs, adults receiving valproate as monotherapy have the lowest risk of hepatotoxicity. Fatal hepatic dysfunction coincident with valproate may be the result of aberrant drug metabolism. Concomitant use of AEDs that induce microsomal P450 enzymes (e.g., phenytoin and phenobarbital) may enhance the production of a toxic metabolite, and hence the greater risk of hepatotoxicity with polypharmacy.     

Vascular Malformations and Epilepsy: Clinical Considerations and Basic Mechanisms

Summary: Vascular malformations (VMs) are associated with epilepsy. The natural history of the various VMs, clinical presentation, and tendency to provoke epilepsy determine treatment strategies. Investigations have probed the mechanisms of epileptogenesis associated with these lesions. Electrophysiologic changes are associated with epileptogenic cortex adjacent to VMs. Putative pathophysiologic mechanisms of epileptogenesis include neuronal cell loss, glial proliferation and abnormal glial physiology, altered neurotransmitter levels, free radical formation, and aberrant second messenger physiology.     

Classification of methods in transcranial Electrical Stimulation (tES) and evolving strategy from historical approaches to contemporary innovations

Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of transcranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. We conclude with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES.     

Carbamazepine Efficacy and Utilization in Children

Summary: Carbamazepine is effective for preventing partial and generalized tonic-clonic seizures in children. Although absence epilepsies are more common in children than adults, an estimated 80% of children with epilepsy have seizure types or epilepsies that are potentially responsive to carbamazepine. The differential diagnosis of ictal staring is an especially important issue in children because absence and atypical absence seizures are more prevalent in children than adults. Age-related pharmacokinetic differences and drug interactions are major considerations in children. On average, children have higher clearance rates of carbamazepine, shorter half-lives, and higher ratios of carbamazepine-10, 11-epoxide to carbamazepine than adults. In addition, children with severe epilepsy are more likely to require multiple-drug therapy, which can lead to complex drug interactions. When carbamazepine is administered along with valproate, drug protein binding interactions can cause intermittent side effects.     

Neonatal Seizures: Problems in Diagnosis and Classification

Summary: The clinical identification of neonatal seizures is critical for the recognition of brain dysfunction; however, diagnosis is often difficult because of the poorly organized and varied nature of these behaviors. Current classification systems are limited in their ability to communicate motor, autonomic, and electroencephalo-graphic features of seizures precisely and to provide a basis for uniform effective diagnosis, therapy, and determination of prognosis. Recent investigations of neonates, utilizing bedside electroencephalographic/polygraphic/ video monitoring techniques, have provided the basis for improved diagnosis and classification of seizures in the newborn. These studies have demonstrated that not all clinical phenomena currently considered to be seizures require electrocortical epileptiform activity for their initiation or elaboration. In addition, the specific clinical character of the phenomena considered to be seizures, the clinical state of the infant, and the character of the EEG indicate the probable pathophysiological mechanisms involved and suggest probable etiologies, prognosis, and therapy. Similarities between animal models that demonstrate reflex physiology and neonates with motor automatisms and tonic posturing suggest that these clinical behaviors may not be epileptic in origin but, rather, primitive movements of progression and posture mediated by brainstem mechanisms. Although not all clinical behaviors currently considered to be neonatal seizures may have similar pathophysiological mechanisms, they are clinically significant because they all indicate brain dysfunction.     

Valproate Monotherapy in the Management of Generalized and Partial Seizures

Summary: For decades, therapeutic tradition has promoted the concept of polypharmacy in the management of epilepsy. In recent years, however, studies have shown that, for most patients, monotherapy can provide comparable or better seizure control than administration of multiple anticonvulsants, while diminishing the potential for adverse reactions, drug interactions, and poor compliance. Valproate is an important monotherapeutic agent that is highly effective in the control of idiopathic primary and secondarily generalized epilepsies, and partial seizures that do not generalize. Comparative studies have found that valproate is at least as effective as phenytoin and carbamazepine in the treatment of generalized and partial seizures. Given the similar efficacy, other factors such as pharmacokinetics and side effects may therefore determine anticonvulsant selection for monotherapy.     

Un nouveau cadre conceptuel de travail pour la psychiatrie

In an attempt to place psychiatric thinking and the training of future psychiatrists more centrally into the context of modern biology, the author outlines the beginnings of a new intellectual framework for psychiatry that derives from current biological thinking about the relationship of mind to brain. The purpose of this framework is twofold. First, it is designed to emphasize that the professional requirements for future psychiatrists will demand a greater knowledge of the structure and functioning of the brain than is currently available in most training programs. Second, it is designed to illustrate that the unique domain which psychiatry occupies within academic medicine, the analysis of the interaction between social and biological determinants of behavior, can best be studied by also having a full understanding of the biological components of behavior.