三种鼠脑胶质瘤模型的建立与比较

目的 ;建立GL261胶质瘤细胞C57BL/6小鼠、C6胶质瘤细胞SD大鼠及BALB/c小鼠皮下动物模型,比较其肿瘤生长特点。方法借助动物立体定向仪,将体外培养小鼠GL261、大鼠C6胶质瘤细胞分别接种于C57BL/6小鼠及SD大鼠右侧尾状核区,C6胶质瘤细胞接种于BALB/c小鼠左前肢皮下。接种后观察不同种实验鼠的生存状态及肿瘤的生长特性,颅内模型于接种后7d、14d、21d、28d进行MRI检查,皮下模型测量体积,并绘制生长曲线。解剖标本,做组织病理学和胶质纤维酸性蛋(GFAP)免疫组化检查。结果 GL261胶质瘤细胞C57BL/6小鼠模型较之后两种模型在组织病理学上接近人脑胶质瘤,而且颅内生长稳定,成瘤率高,未见颅外转移病灶,实验周期短,重复性好。结论 GL261胶质瘤细胞C57BL/6小鼠模型,其肿瘤生长特性及病理特征与人脑胶质瘤相似,可作为临床胶质瘤基础研究的理想模型。     

颅内胶质瘤模型建立及肿瘤生长特征观察

目的建立Wistar、SD大鼠及BALB/c小鼠脑胶质瘤动物模型,比较其颅内肿瘤生长特点.方法借助动物立体定向仪,将体外培养大鼠C6胶质瘤细胞(细胞数为3×105个,悬浮于无血清DMEM培养液60 μl中)分别接种于Wistar、SD大鼠左侧尾状核区, BALB/c小鼠左顶枕区(接种细胞数为1×103).接种后观察不同种实验鼠的生存状态及肿瘤的生长特性,分别于接种后5、15 d进行MRl检查.在实验3 d、6 d、9 d、12 d、15 d时解剖标本,做组织病理学和胶质纤维酸性蛋白(GFAP)免疫组化检查.结果两种大鼠脑胶质瘤动物模型在组织病理学上接近人脑胶质瘤.而且具有颅内生长稳定,成瘤率高,未见颅外转移病灶,实验周期短,重复性好.而BALB/c小鼠成瘤率76.67%.结论接种的Wistar、SD两种大鼠脑胶质瘤动物模型,其肿瘤生长特性及病理特征与人脑胶质瘤相似.均可作为临床胶质瘤基础研究的理想模型.而BALB/c小鼠则需进一步探索.     

立体定向大鼠C6脑胶质瘤动物模型的建立

目的通过立体定向在SD大鼠右尾状核区接种C6细胞,建立类似于人脑胶质瘤的动物模型.方法SD大鼠在立体定向条件下,左右尾状核区接种1×106个C6胶质瘤细胞,接种后观察实验大鼠的生成状态,分别于接种后1,2,3周时进行MRI检查.在实验三周时解剖标本,做组织病理学和GFAP免疫组化检查.结果该方法建立的胶质瘤动物模型在组织病理学上接近人脑胶质瘤,而且具有颅内生长稳定,成瘤率高,没有颅外种植生长,实验周期短,重复性好.结论该大鼠脑胶质瘤动物模型能够满足胶质瘤实验治疗研究的需要,而且在细胞接种后1～2周,为实验治疗较好的时机.     

BALB/c小鼠C6脑胶质瘤模型的建立及生长特性观察

目的建立BALB/c小鼠C6脑胶质瘤模型,观察其生长特性.方法将体外培养的细胞数为1×103,1×104,5×104个分别悬浮于无血清DMEM培养液10μl中的C6胶质瘤细胞接种于BALB/c小鼠左顶枕区,观察不同C6细胞浓度实验鼠的生存状态及肿瘤生成率.对自然死亡荷瘤鼠行组织病理学和胶质纤维酸性蛋白(GFAP)免疫组织化学检查.另外,在实验3 d、6 d、9 d、12 d、15d、20 d时解剖实验鼠,对肿瘤体积进行统计测量.结果该方法建立的胶质瘤动物模型在组织病理学上接近人脑胶质瘤,且颅内生长稳定.3组成瘤率分别为65%、75%、80%.未见颅外转移病灶,实验周期短,重复性较好.结论BALB/c小鼠C6脑胶质瘤模型的肿瘤生长特性及病理特征与人脑胶质瘤相似,可作为临床胶质瘤基础研究的理想模型.     

大鼠脑胶质瘤模型建立与生长评估

目的建立SD大鼠脑胶质瘤动物模型,比较其生长评估方法。方法采用立体定向技术,将体外培养的大鼠C6胶质瘤细胞浓缩悬置,调制为浓度5×1011/L的无血清RPMI1640培养液,将20μl悬液接种于SD大鼠右侧尾状核区。接种后分时段观察与评估实验鼠的神经功能缺损、肿瘤的生长特性、MRI检查结果,并做组织病理学和胶质纤维酸性蛋白及S-100蛋白免疫组化检查。结果立体定向技术接种的大鼠脑胶质瘤动物模型具有颅内生长稳定,成瘤率高,未见颅外转移,实验周期短,可重复性好,组织学上接近人脑胶质瘤等特征。神经功能评分与荷瘤鼠的脑胶质瘤大小及生长进程具有相关性。结论建立的SD大鼠的C6脑尾状核胶质瘤模型,其肿瘤影像及病理特征与人脑胶质瘤相似,神经功能评分可作为其生长的间接评估方法。     

大鼠脑内C6胶质瘤模型的建立

目的建立稳定可靠的大鼠脑内C6胶质瘤模型。方法取20只健康成年SD大鼠,用立体定向技术将含1×106个C6胶质瘤细胞的悬液15μl缓慢接种于大鼠左侧尾状核区;接种后3周时随机挑选其中10只大鼠麻醉后行MRI检查,观察肿瘤影像学表现,随后处死大鼠取出肿瘤组织,行免疫组化及HE染色检测肿瘤生长情况;另外9只(麻醉死亡1只)大鼠继续饲养直至死亡,观察其生存时间。结果1只接种肿瘤细胞后出现短暂体重下降,但未出现明显神经系统体征,饲养60 d后尸检未见肿瘤生长;其余18只大鼠颅内均有肿瘤生长且无颅外转移现象,病理学检查结果显示脑内肿瘤呈浸润生长,可见新生血管,胶质纤维酸性蛋白表达阳性。荷瘤鼠生存时间为25~47 d,平均(32.78±2.34)d。结论采用立体定向方法向大鼠尾状核区种植C6细胞可获得较为稳定、可靠的胶质瘤动物模型,能够满足胶质瘤动物实验研究的需要。     

大鼠C6脑胶质瘤模型的建立

目的通过不同方法建立大鼠脑胶质瘤模型,观察其生长特性,比较各种方法的优劣。方法体外培养大鼠C6胶质瘤细胞,分别取浓度为1.0×105个/10μl、1.0×106个/10μl、1.0×107个/10μl细胞悬液,立体定向接种于Wistar大鼠脑右侧尾状核区,观察不同接种量实验鼠的生存状态、成瘤情况及脏器转移灶,并采用免疫组织化学方法检测其胶质纤维酸性蛋白(GFAP)、血管内皮生长因子(VEGF)的表达。结果各种接种量的实验组成瘤率均为100%,未见颅外转移病灶,在组织病理学上接近人脑胶质瘤,瘤细胞病理性核分裂像多见,GFAP蛋白呈散在阳性表达,VEGF蛋白呈强阳性表达,瘤组织内有出血和坏死以及丰富的微血管。实验周期短,重复性高。结论C6细胞接种Wistar大鼠脑胶质瘤动物模型,肿瘤成瘤率高,颅内生长稳定,肿瘤组织病理学特性与人脑胶质瘤相似,可作为临床胶质瘤基础研究的理想模型。实验范围内部分时段不同接种剂量肿瘤生长速度有显著性差异,可根据病因学、实验治疗或药效学等不同研究需要选择不同接种量。     

人脑胶质瘤细胞裸鼠原位移植动物模型的建立

目的探讨人脑胶质瘤细胞裸鼠原位移植动物模型建立的技术方法。方法借助动物立体定向仪的引导,采用微注射方法将体外培养人脑胶质瘤细胞U87MG(悬浮于无血清RPMI 1640培养液中,细胞数为108/ml)接种于裸鼠(BALB/c)额叶白质区。接种后观察不同种实验鼠的生存状态,分别于接种后1 h至63 d的不同时间进行裸鼠脑肿瘤组织病理学检查和免疫组织化学分析。结果裸鼠脑内注射体外培养的人脑胶质瘤细胞U87MG的合适速率为0.05μl/min =1μl/20 min,细胞悬液体积1μl,细胞数105,注射时间20 min。按此方案注射U87MG细胞无沿针道返流,恰好在尾状核区形成近圆球形肿瘤体,成瘤率高(100%),肿瘤颅内生长稳定,组织病理学检查符合人脑胶质瘤形态特征,未见脑外转移。结论本研究的人脑胶质瘤细胞裸鼠原位移植动物模型建立方法精确可靠,重复性好。肿瘤符合人脑胶质瘤的生物学特性,该动物模型可作为研究人脑胶质瘤发生、生物学特性以及各种治疗评价的可靠动物模型。     

大鼠C6脑胶质瘤模型的病理特征与MRI的观察

目的建立SD大鼠C6胶质瘤模型并对其病理特征及MRI进行观察。方法50只SD大鼠随机分成5组，每组10只，c6胶质瘤细胞悬液立体定向接种于大鼠的右侧尾状核，接种后观察大鼠的生活状态、生存期；分别于接种后不同时段进行MRI观察肿瘤生长特性及肿瘤体积的测量；取不同时段组大鼠脑标本行脑组织HE染色、透射电镜(transmission electron microscope，TEM)、脑组织含水量测量(与10只正常大鼠对照)、胶质纤维酸性蛋白(GFAP)免疫组化检查。结果立体定向颅内接种成功率97．5％，未见远处及颅外转移，肿瘤在一定时期内牛长较快，脑水肿随肿瘤的生长明显加重，生存期观察组中7只荷瘤鼠死亡，3只肿瘤自发部分消退。结论立体定向建立大鼠C6胶质瘤模型成功率高，接种后颅内肿瘤呈浸润性生长，与人脑胶质瘤具有相似性，由于生存期观察组中有部分荷瘤鼠出现肿瘤自发部分消退，故应用该模型评价治疗效果时应慎重；TIWI增强扫描可清晰显示肿瘤影像，且能更早发现肿瘤；MRI联合病理可较好反映肿瘤生长方式及发展过程。     

大鼠脑干胶质瘤模型的建立及MRI特点

目的 建立大鼠脑干胶质瘤模型,并研究成瘤鼠运动功能及胶质瘤MRI成像特点.方法 采用大鼠脑立体定向仪,将C6胶质瘤细胞接种至SD大鼠脑干内.MRI动态观察肿瘤生长情况,并观察接种C6胶质瘤细胞后大鼠的运动能力、生存周期等.结果 C6胶质瘤细胞接种成功率为100%.生存分析表明:大鼠于接种后第16～22天死亡.接种后第7天,MRI即可检出肿瘤生长,荷瘤鼠的运动能力随着成瘤时间的推移逐渐减弱.结论 大鼠脑干胶质瘤模型成瘤率高,有良好的可重复性和可预测性.MRI观察该模型具有脑干胶质瘤成像的特点,细胞接种后10～18 d是最佳观测期.     

Diagnostic Difficulties and Treatment Implications

Summary: Differentiation between types of epileptic seizures has been aided in recent years by the introduction of intensive neurodiagnostic techniques and the development of increasingly detailed classification systems. Paradoxically, these developments have not simplified the task of matching the appropriate antiepileptic drug to a particular seizure type. It is reasonable to assume that anticonvulsant drugs will have different effects on different types of seizures, but faulty, circular reasoning can enter the picture if one also assumes that responses of seizures to different drugs signify different seizure types. There are several examples of differential diagnoses that can fall prey to this problem, including the diagnosis between partial seizures with secondary generalization and generalized tonic-clonic seizures, and the diagnosis between complex partial seizures and absence seizures with automatisms, among others. Considerations of etiology in future classification systems can further complicate the problem: should one then choose an anticonvulsant drug on the basis of individual seizure type or on the basis of the type of epilepsy? Ramifications of this issue extend even to the drug approval process. Official sanction is not given for use of a drug for a seizure type not included in the original efficacy studies, even if later scientific evidence shows that seizure type to be related to a type that is included. New trials must be undertaken. These problems arise from how we choose to classify seizures.     

Cognitive Dysfunction Associated with Antiepileptic Drug Therapy

Summary: Epilepsy is frequently associated with cognitive dysfunction. However, the reasons for this correlation are unclear. Possible influential factors include patient age; duration, frequency, etiology, and type of seizures; hereditary factors; psychosocial issues; and antiepileptic drug (AED) therapy. Whereas many of these factors are beyond the physician's control, AED therapy is one element that can be addressed in treatment decisions by recognizing the potential cognitive effects of particular AEDs. For example, phenobarbital impairs memory and concentration; phenytoin affects attention, problem solving ability, and performance of visuomotor tasks. In contrast, carbamazepine may affect concentration, while valproate would appear to have minimal effects on cognition. Moreover, cognitive effects of AEDs are amplified with coadministration of multiple anticonvulsants (polytherapy). A review of studies on the cognitive effects of monotherapy with AEDs, as opposed to those of polytherapy, provides evidence that drug-related cognitive dysfunction can be reversed if patients are switched to a simpler therapeutic regimen. Future research should be directed toward developing reliable measures for assessing and monitoring cognition, and understanding the particular cognitive side effects of each AED. Physicians also need to revise their opinions about which side effects are "tolerable" for epileptic patients.     

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.     

Carbamazepine Efficacy in Adults With Partial and Generalized Tonic-Clonic Seizures

Summary: Carbamazepine and phenytoin are drugs of choice in initial monotherapy for adult partial and secondarily generalized tonic-clonic seizures. These designations reflect the results of the Veterans Administration Epilepsy Cooperative Study Group of 1985. An earlier comparative study of carbamazepine and phenytoin by Ramsay and associates found both drugs equally effective in controlling new-onset seizures. Among the advantages of carbamazepine is that it causes relatively few cognitive and dysmorphic side effects. Its disadvantages are its unavailability in parenteral formulation and its metabolic autoinduction. The latter must be compensated for by planned dosage increases to maintain therapeutic plasma steady-state levels during the first 2 or 3 months of treatment. Carbamazepine is judged a drug of choice in the treatment of these secondarily generalized tonic-clonic seizures, and the drug of choice in children, adolescents, and women susceptible to the dysmorphic side effects associated with other anticonvulsant agents.     

Etiologic and Preventive Aspects of Epilepsy in the Child–Bridging the Gap Between Laboratory and Clinic

Summary: Four broad categories of basic phenomena are pertinent to developing ways to prevent epilepsy. These include mechanisms of epileptogenesis, ictal initiation and temporary entrainment by the seizure discharge of normally functioning brain, seizure propagation, and control mechanisms that function both to restrain the cascade of epileptic events culminating in a seizure and to arrest the epileptic event and restore the interictal state. In newborns and children, hypoxia-ischemia is a major factor leading to epileptogenesis, and several schemes are proposed to classify, quantify, and prevent hypoxic-ischemic encephalopathy. Control mechanisms must be better understood in order to develop prophylactic recommendations for epilepsy, and an experimental model of "kindling antagonism" may increase our understanding of these. Programs of prevention of seizures in children will evolve only if basic researchers and clinicians work productively together to develop an adequate understanding of factors important in epileptogenesis and antiepileptogenic control mechanisms.     

Predisposing and Causative Factors in Childhood Epilepsy

Summary: We review information from large studies of defined populations, examining the role of known factors and especially of prenatal and perinatal factors in contributing to nonfebrile seizure disorders of early childhood. We depend especially, but not exclusively, on the recently completed analyses from the Collaborative Perinatal Project of the National Institute of Neurological and Communicative Disorders and Stroke, the NCPP. About 4% of children in the NCPP who had at least one non-febrile nonsymptomatic seizure by the age of 7 years had a previous seizure during acute neurologic illness, such as meningitis or during the acute illness after trauma. Many such seizures should potentially be preventable. Of children with seizures, 10% had had a neonatal seizure and 13% had had a febrile seizure. Among the hundreds of prenatal and perinatal factors explored as predictors of childhood seizure disorders, the principal predictors identified were congenital malformations of the fetus, cerebral and noncerebral; family history of certain neurologic disorders; and neonatal seizures. In agreement with the British National Child Development Study, labor and delivery factors in the NCPP appeared to contribute very little to childhood seizure disorders. Maldevelopment, rather than damage at birth to an initially intact nervous system, appeared to be the more common mechanism. Most seizure disorders of early childhood remained unexplained by the large set of prenatal and perinatal characteristics examined.     

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.     

Treatment Considerations in Anticonvulsant Monotherapy

Summary: The long-standing practice of polypharmacy in treating epilepsy is giving way to use of monotherapy. Monotherapy can improve seizure control as well as reduce the risk of serious idiosyncratic reactions, dose-related side effects, and complex drug interactions. Monotherapy also offers improved compliance and cost-effectiveness. The basis of monotherapy is accurate diagnosis and assessment of the patient's seizure type(s), followed by selection of a single appropriate anticonvulsant drug. Many patients currently treated with multiple anticonvulsants can be successfully converted to monotherapy with a carefully monitored program in which troublesome and redundant drugs are gradually withdrawn from the therapeutic regimen.     

Anticonvulsant Drugs and Cognitive Function: A Review of the Literature

Summary: Alterations of cognitive function are separate from disturbances of behavior seen in association with epilepsy. The nature of the cognitive disability may to a certain extent depend on the seizure type. Partial seizures, mainly derived from a temporal lobe focus, impair memory tasks, while generalized seizures seem to have more effect on attentional abilities. A number of studies, reviewed in this paper, suggest that anticonvulsant drugs further impair cognitive function. Maximal impairments are seen in patients receiving polytherapy: rationalization of polytherapy improves cognitive abilities. Studies in children and adults have allowed differentiation of the effects of various commonly used antiepileptic agents. Maximal cognitive deficits are seen with. phenytoin, while phenobarbital and sodium valproate induce moderate disturbances, and carbamazepine seems relatively free from such toxicity. Further research is needed on the interrelationship between types of seizure disorders, types of anticonvulsant medications, and cognitive function.     

Dextromethorphan: Cellular Effects Reducing Neuronal Hyperactivity

Summary: Dextromethorphan is a dextrorotary morphinan without affinity for opioid receptors, commonly used as an antitussive medication. During the past 5 years, interest in the compound and its demethylated derivative, dextrorphan, has been revived because additional neuroprotective and an-tiepileptic properties were found in in vitro studies, animal experiments, and a few clinical cases. Both morphinans are able to inhibit N -methyl-D-aspartate (NMDA) receptor channels and voltage-operated calcium and sodium channels with different potencies. The inhibition of the NMDA receptor is believed to be the predominant mechanism of action responsible for the anticonvulsant and neuroprotective properties of the compounds.