胶质瘤代谢异常对表观遗传的影响

肿瘤代谢异常和表观遗传修饰异常是肿瘤研究中里程碑式的发现。最近人们发现胶质瘤代谢异常引起的表观遗传修饰改变能影响其发生与发展。如胶质瘤中异柠檬酸脱氢酶1(IDH1)基因突变能增加2-羟基戊二酸(2-HG)含量,2-HG能竞争抑制DNA脱甲基酶和组蛋白脱甲基酶等,导致DNA甲基化水平增高;增高的丙酮酸激酶M2(PKM2)能入核调控表观遗传修饰,磷酸化组蛋白H3T11等位点,促进基因转录、细胞增殖;叶酸不足或代谢酶障碍导致通用甲基供体——S-腺苷甲硫氨酸(SAM)不足及DNA低甲基化。本文就胶质瘤代谢异常对表观遗传的影响进行综述。     

物质成瘾的表观遗传机制

<正>表观遗传(epigenetic)是指在基因DNA序列没有发生改变的情况下,基因表达发生可遗传的改变,并最终导致可遗传的表型变化,而且这种改变在个体发育和细胞增殖过程中能稳定遗传并具有可逆潜能。表观遗传包括DNA甲基化、组蛋白修饰、非编码RNA调控等。表观遗传参与大脑分化与发育,越来越多证据表明,表观遗传机制参与精神分裂症、双相情感障碍、物质成瘾、孤独症等精神障碍     

胶质瘤恶性进展相关基因PASG敲除后基因表达谱的改变

目的探索胶质瘤恶性进展相关PASG基因与胶质瘤发生发展的关系。方法选择性敲除PASG基因7.126kb基因组DNA序列(含该基因第10～12个外显子),并从形态学及全基因组基因表达水平观察基因敲除后的改变。结果PASG基因敲除鼠全基因组表现为低甲基化水平。海马区皮层的大锥体细胞存在细胞形态、排列层次和数量的异常。鼠脑全基因组差异基因表达谱分析显示:PASG基因敲除后,表达差异超过1.6倍的基因共有123条,其中61条表达下调,62条表达上调。结论PASG基因作为上游调控基因,通过改变基因组甲基化水平调控下游一系列细胞增殖分化相关基因表达。PASG基因表达异常导致下游相关基因的表观遗传修饰改变可能是胶质瘤发生发展的早期分子事件,值得进一步深入研究。     

表观遗传机制及其在帕金森病中的作用

帕金森病（Parkinson disease，PD）的确切病因及发病机制未明。目前认为该病与老化、遗传和环境因素密切相关。资料表明遗传因素在PD的发病中起重要作用。然而，此方面的研究更多侧重于对DNA本身序列的关注。对基因表达调控的研究，更多着眼于各种调控蛋白分子与DNA序列的结合和对相关基因表达活性的调节。自1996年发现转录调节蛋白（CREB binding protein，CBP）具有内源性组蛋白乙酰转移酶（histone acetylase，HAT）活性以来，人们逐渐认识到有些表型和疾病的发生并非DNA序列的改变，而是表观遗传（epigenetic）改变所导致。因此，表观遗传学成为基因转录调控研究的一个新热点，其在PD发病中的作用也日益受到重视。我们就目前人们对表观遗传机制的认识及其在PD中的可能机制做一简单介绍。     

抗精神病药在精神分裂症表观遗传调控中的研究进展

<正>精神分裂症是受基因和环境因素双重影响的复杂精神疾病。精神分裂症易感基因的遗传缺陷和表观遗传调控分子相互作用可导致疾病发生。目前已知表观遗传调控紊乱主要包括DNA甲基化、组蛋白修饰异常以及微小RNA(microRNA,miRNA)表达失调等。理论上,表观遗传修饰具     

DNA甲基化异常与垂体腺瘤研究进展

DNA甲基化是已知的哺乳动物DNA唯一的自然化学修饰方式,与基因表达调控、染色体稳定性及细胞分化有关,在肿瘤的发生过程中起着重要的调节作用。DNA甲基化异常可发生在多数人类肿瘤及癌前病变中,其主要在转录水平抑制基因的表达。垂体腺瘤是颅内常见的一种良性肿瘤,发病机制尚不完全清楚,近年研究表明DNA异常甲基化与垂体腺瘤发生关系密切,本文综述了DNA甲基化的现状、DNA异常甲基化在肿瘤发生中的作用、垂体腺瘤相关基因异常甲基化模式和基因表达的关系及去甲基化对垂体肿瘤治疗的应用前景和意义。     

表观调控与神经干细胞分化

神经干细胞是当前神经科学领域的研究热点。最近的研究显示表观调控与神经干细胞的分化关系密切,而且为神经干细胞的移植治疗提供可能的细胞来源。表观调控是指在基因的DNA序列未改变的情况下,基因功能发生可遗传的变化而导致细胞表型发生改变,主要机制包括DNA甲基化、组蛋白修饰、基因印迹、染色体重组以及非编码小RNA等。本综述就表观调控对神经干细胞分化作用的最新进展作一回顾。     

表观调控与神经干细胞分化(英文)

神经干细胞是当前神经科学领域的研究热点。最近的研究显示表观调控与神经干细胞的分化关系密切,而且为神经干细胞的移植治疗提供可能的细胞来源。表观调控是指在基因的DNA序列未改变的情况下,基因功能发生可遗传的变化而导致细胞表型发生改变,主要机制包括DNA甲基化、组蛋白修饰、基因印迹、染色体重组以及非编码小RNA等。本综述就表观调控对神经干细胞分化作用的最新进展作一回顾。     

儿童弥漫内生型桥脑胶质瘤H3K27M突变的研究进展

表观遗传学是指表观遗传学改变对表观基因组基因表达的调节,这种调节不依赖基因序列的改变且可遗传表观,而组蛋白修饰是一种重要的表观遗传学改变,调节基因表达。异常组蛋白修饰调控癌基因/抑癌基因表达,影响肿瘤的发生与发展,如组蛋白H327位赖氨酸被蛋氨酸替代(Histone H3 lysine to methionine substitution on position 27,H3K27M)导致氨基酸亚基甲基化改变,常与肿瘤发生相关。     

抑郁症与表观遗传学

表观遗传学的概念由Waddington在1939年提出,目前认为它主要研究不涉及DNA序列突变的可逆性、可遗传性基因功能调控,这种调控主要通过DNA甲基化状态、组蛋白修饰的改变及非编码RNA的作用而实现旧0。哺乳动物的DNA甲基化主要发生在CpG二联核苷酸中胞嘧啶的第5位碳原子上,而CpG二联核苷酸在基因启动子区的CpG岛较为密集。     

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.     

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.     

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.     

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.     

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.     

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.     

Special Pharmacokinetic Considerations in Children

Summary: Pediatric patients have greater degrees of pharmacokinetic variability and unpredictability than adults. This variability results from the effects of pharmacogenetics, age and growth, prior and current comedication, and disease. Newborns with seizures have the least predictable dosage requirements, and their needs change as drug-eliminating mechanisms mature in the neonatal period. Infants have the highest relative capacities to eliminate antiepileptics of any age group and require the largest relative doses. In addition to age-related trends, children demonstrate the same drug-specific, pharmacokinetic phenomena that adults do, including nonlinear phenytoin elimination, nonlinear valproate binding, and autoinduction of carbamazepine. Intercurrent illness and drug interactions further modify the age-related pharmacokinetic patterns in children and make dosage requirements even more unpredictable. Recent studies have shown that febrile illness can affect drug elimination, sometimes decreasing drug levels by 50% or more. Intermittent treatment with benzodiazepines administered either orally or rectally can be an important adjunct and help minimize this type of problem for children with marginally controlled epilepsy. Intermittent benzodiazepines are also helpful for children who have febrile seizures and who need only occasional antiepileptic protection.