MicroRNAs与可卡因成瘾关系的研究进展

可卡因进入体内会导致海马、前额叶皮层、中脑腹侧被盖区及伏隔核等学习记忆相关脑区的多巴胺、谷氨酸、5-羟色胺(5-hydroxytryptamine,5-HT)等神经递质释放的异常变化,通过作用于相应的受体引发一系列分子事件:包括激活细胞内信号转导通路,改变神经营养因子、转录因子、即刻早期基因或染色体的结构等,并最终引起突触的可塑性,甚     

脑源性神经营养因子在海马突触联系和可塑性中的作用

脑源性神经营养因子在海马突触的传递和可塑性过程中起重要作用 ,与学习和记忆过程密切相关。它可调节海马神经元突触的基础传递 ,不但在海马早期长时程增强中起作用 ,还参与海马的晚期长时程增强。其作用方式包括突触前调控和突触后调控 ,调节途径包括钙离子及其通道、N 乙酰 D 门冬氨酸受体、丝分裂素相关蛋白激酶和3 磷酸肌醇激酶途径等。     

脑源性神经营养因子在衰老和神经系统退行性变中的作用研究进展

脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)是神经营养因子家族中的一员,在维持神经元的生长、分化和神经损伤后的修复与再生中发挥重要作用.海马和大脑皮质被认为是认知、学习和记忆的高级中枢,而认知和记忆能力会随着衰老而逐渐减退,其原因与海马和大脑皮质内,特别是海马内神经元的突触可塑性改变有关.     

老龄海马的BDNF及TrkB mRNA表达与学习记忆的关系

海马是最易受衰老影响的脑区之一 ,其分泌合成多种神经营养因子 ,其中脑源性神经营养因子(BDNF)及其受体TrkB的老龄性改变较为显著 ,两者的mRNA随增龄而显著降低 ,而在阿尔采默病 (AD)等有认知功能障碍的疾病时表现更为突出。另外 ,BDNF及其受体参与海马学习记忆的过程 :①BDNF通过基底前脑胆碱能系统调节学习记忆 ;②BDNF通过调节突触传递易化长时程增强 (LTP)。因此 ,本文将就BD NF及其受体TrkB的老龄性改变和其对学习记忆的调控两大方面作进一步的探讨。     

LTP形成机制的研究进展

突触传递的长时程增强 (LTP)是学习记忆的神经基础之一 ,是突触可塑性的功能性指标之一 ,也是研究学习记忆的理想模型。LTP是突触前后机制共同作用的结果 ,包括诱导和维持 2个阶段。LTP的形成与突触前递质的释放、突触后相关受体通道以及各种蛋白激酶、逆行信使、即早基因等密切相关。     

学习记忆与突触可塑性及相关物质的研究

突触可塑性反映了行为的可塑性，与学习记忆密切相关。一氧化氮(NO)、神经生长相关蛋白(neuronal growth associated protein，GAP-43)、神经细胞粘附因子(neural cell adhesion molecule，NCAM)和生长抑素(somatostatin，SOM)对突触可塑性具有重要意义。NO介导了兴奋性神经传导，对海马、小脑等神经元上突触可     

铝暴露对海马NMDA受体的影响

铝是一种慢性神经毒性物质,能影响神经系统的多种功能,特别是对学习和记忆功能有抑制作用。铝可通过改变神经细胞的膜功能和NMDA受体等途径影响细胞内外的钙稳态,造成细胞结构和功能障碍,导致学习记忆能力出现不同程度的下降。NMDA受体是中枢谷氨酸盐兴奋性受体的一种,参与突触可塑性及皮质和海马神经元长时程增强(LTP)效应。NMDA受体通道在学习记忆中开启和学习记忆、神经元可塑性及大脑发育等方面均起重要作用。     

神经营养因子对颅脑损伤保护作用的研究进展

神经营养因子广泛存在于脑及周围神经系统.无论在体内或体外它们都能促进神经系统的发育,维持神经元的生长、存活与分化;并可影响神经系统的突触可塑性.神经营养因子通过激活其特异性高亲和力酪氨酸激酶受体自身磷酸化而进行信号传递.颅脑损伤可以诱导神经营养因子基因表达,从而对受损的神经元产生保护作用,促使神经元功能恢复.     

脑兴奋性突触后NMDA受体信号转导复合物

在脑兴奋性突触中,N甲基D天(门)冬氨酸受体和各种信号蛋白在突触后形成了一个多蛋白的NMDA受体复合物,共同调控着神经信号由突触前向细胞内的传导以及在细胞内的级联释放、传递,介导突触强度的长期变化,并参与突触可塑性、学习记忆和认知等多种神经功能。NMDA受体复合物由受体、衔接蛋白、信号蛋白和骨架蛋白等上百种蛋白组成,各种蛋白在突触后形成了一个蛋白间相互作用的网络,编码神经信号,将电信号转化为生化变化,从而精密地调控着神经功能。对NRC组成和功能的研究将有助于阐明其在突触可塑性、学习记忆和认知中的作用机制。     

NMDA受体和NADPH黄递酶在大鼠下丘脑室旁核分布的研究

<正>NMDA受体是中枢兴奋性氨基酸受体的重要部分,它和突触可塑性,学习记忆等许多复杂的功能有关.近年来的研究证明,一氧化氮(NO)可能作为一种神经递质,它能激活鸟嘌呤核苷酸环化酶,提高谷氨酸受体     

Secular change in menarche in women in Madrid

The age at menarche was estimated by recollection in 1617 women between the ages of 18 and 60 in Madrid and a nearby suburb, Pinto. The population of Pinto is working-class and the Madrid group, taken from residential neighbourhoods , belongs to the upper middle class. In both groups we found a diminution in average age at menarche, from 14.04 to 13.02 years in Madrid and from 14.55 to 13.16 years from about 1935 to about 1965 in Pinto. These changes have been more intense in the group which is less well-off economically, where living conditions have varied much more drastically.     

Intestinal helminthiasis in school children in Haiti in 2002

A survey on intestinal helminths in school children was conducted in Haiti in 2002. This first nationwide study involving the entire country was stratified by department according to urban and rural zones using the cluster method. Focusing on elementary school children (n=5792; age range 3 to 20 years), it involved 26 urban and 49 rural schools randomly selected. Stools were preserved in formalin and examined by the Ritchie technique. Thirty-four per cent of stools (1981/5792) tested positive for intestinal helminths with the following parasites identified: Ascaris lumbricoides (27.3%), Trichuris trichiura (7.3%), Necator americanus (3.8%), Hymenolepsis nana (2%), Taenia sp. (0.3%) and Strongyloides stercoralis (0.2%). The helminth prevalence was higher in rural (38.4%) compared to urban areas (30%). There was no significant difference in prevalence by sex and age. The importance of geohelminths changed from one department to another with the highest prevalence found in the Southern department of Grande Anse (73.7%) and the lowest prevalence in the Center department (20.6%). Five out of the country's nine departments had a similar prevalence varying from 25.5% to 28.2%. Intestinal helminthic polyparasitism was observed in a percentage of infested school children comprise between 3.4% and 28.6% according in relation to the geographical area. A program to fight against geohelminths in school children should be initiated as a public health priority. Albendazole is the drug of choice. Frequency of drug distribution should be based on the prevalence of geohelminths in each department.     

Experience in adult population in dengue outbreak in Delhi

A dengue outbreak has recently hit the Indian capital. We studied the clinical profile of adult patients. Five hundred and sixty patients of dengue infection were admitted in a specially created ward according to the criteria laid down by WHO. Haematemesis (28.28%), epistaxis (26.78%) and malena (14.28%) were some of the common presentations. Similarly lymphadenopathy, especially cervical (30.89%), palatal rashes (26.96%) and hepatomegaly (23.75%) were the most commonly encountered findings on physical examination. Most of the cases were of dengue fever with haemorrhage and only 2.5% cases were classified under dengue haemorrhagic fever or dengue shock syndrome. The average hospital stay was 3.4 days but only 9.8 hours in the eleven patients who died, suggesting their late arrival in preterminal situation giving little time for resuscitation. Thrombocytopenia was not a feature and only 12.85% patients had platelet count less than 70,000/cmm. Most of the patients who were admitted with thrombocytopenia, showed normalization in their platelet counts in next few days. Serological examination demonstrated evidence of recent dengue infection in 41.17% patients. Few patients required blood or platelet concentrate transfusion. Eleven patients died, three due to DIC, one of intracranial haemorrhage and seven due to massive gastric haemorrhage. Rest of the patients recovered completely. Thus we can conclude that recent outbreak in Delhi was of dengue fever with haemorrhage and mortality was very low in patients who came early to the hospital.     

Changes in the hypothalamic nuclei in in experimental allergy

Summary In rabbits subjected to prolonged sensitization and in which the Arthus phenomenon was induced there was a marked reaction of the hypothalamic nuclei. Staining by Gomori's method indicated a cellular swelling, loss of granules, and protoplasmic vacuolization in the supraoptic nucleus. There was a considerable increase in the size of the cross-sectional area of the cells. The same effects were much less well shown in the paraventricular nucleus. These results show that marked signs of increased neurosecretion developed in the animals at the height of the Arthus phenomenon.(Presented by Active Member AMN SSSR V. V. Parin) Translated from Byulleten Éksperimental'noi biologii i Meditsiny, Vol. 55, No. 4, pp. 110–113, April, 1963.     

Development in in vitro toxicology

There are three principal pressures driving the development of in vitro toxicology: (1) the need for more efficient testing systems to cope with the large number of xenobiotics currently being developed; (2) public pressure to reduce animal experimentation; and (3) a need for a better understanding of the mechanisms of toxicity. Within this, in vitro toxicology is focused on local, systemic, and target-organ toxicity. It is becoming increasingly apparent that a step or decision-tree approach using input of a variety of experimental data (physicochemical properties, biokinetics, cytotoxicity) provides the most efficient system for predicting toxicity. Examples of the use of in vitro toxicity systems for prediction of systemic toxicity and target-organ (liver) toxicity are presented.Originally presented at ECCP 93.