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1.
巩燕  叶治家 《生命的化学》2001,21(6):490-491
1 .sIL 1 6的来源与结构白细胞介素 1 6(interleukin 1 6,IL 1 6) ,又名淋巴细胞趋化因子 (lymphocytechro mataxisfactor ,LCF) ,是 1 982年由CruikShank实验室从抗原刺激的单核细胞中分离提纯的[1] ,主要来源于外周血单核细胞 ,它的前体由 63 1个氨基酸构成 ,无生物学活性 ,被白介素 1 β 转化酶 (caspase 3 ,interleukin 1 β con vertingenzymeICE/CED 3 protease)在Asp5 10 和Ser5 11位酶切后[2 ] ,形成 1 2 1个氨基…  相似文献   

2.
阿尔茨海默病相关的早老蛋白与Notch和Wnt信号通路   总被引:2,自引:0,他引:2  
自 1 995年发现高度同源的早老蛋白(presenilin ,PS) 1、2基因突变可导致家族性早发型阿尔茨海默病 (Alzheimerdisease ,AD)以来 ,目前不仅已证实PS参与老年斑核心物质β 淀粉样蛋白 (β amyloid ,βA)的形成 ,还发现PS是一种多功能蛋白质 ,与细胞内的多种信号转导通路有关。PS介导Notch、Wnt/Wingless信号转导的机制、及其与AD病理改变的关系已成为AD研究领域的一个新的关注点。1 .PS和Notch信号通路的关系Notch信号在神经元发育中有重要作用 ,通过旁侧抑制…  相似文献   

3.
阿尔茨海默病 (Alzheimer′sdisease ,AD)是一种以进行性认知障碍和记忆能力损害为主的中枢神经系统退行性疾病。其病理特征为神经元内出现大量双股螺旋纤丝 (pairedhelixfilament,PHF)和细胞外间隙出现 β 淀粉样蛋白 (β amyloid ,Aβ)的沉积 ,即神经元纤维缠结 (neorofibrillarytangles,NFT)和老年斑(senileplaque,SP)的大量存在以及选择性的神经元和突触的丢失[1] 。AD可分为家族性 (FAD)和散发性 (SAD)。神经生长抑制因子 (neur…  相似文献   

4.
蛋白激酶A与阿尔茨海默病   总被引:1,自引:0,他引:1  
阿尔茨海默病 (Alzheimerdisease ,AD)是老年痴呆症中最常见的一种 ,主要表现为进行性的记忆和认知功能障碍。目前AD的病因和发病机制尚不明了。神经原纤维缠结(neurofibrillarytangle ,NFT)作为AD的特征性病变 ,与临床痴呆症状呈正相关 ,提示NFT在AD的发病过程中可能发挥重要作用[1] 。NFT以成对螺旋丝样结构 (pairedhelicalfila ment,PHF)存在 ,其主要成分是异常过度磷酸化的tau蛋白 (tauprotein) [2 ] 。Tau蛋白在成人脑中有 6种同分异…  相似文献   

5.
NGAL蛋白     
NGAL(neutrophilgelatinase associatedlipocalin)是lipocalin家族的一个新成员 ,是Kjeldsen等人[1] 在1993年研究中性粒细胞 92kD的明胶酶 ,即MMP 9(基质金属蛋白酶 9)时发现的。随后 ,NGALcDNA及其全基因序列分别于 1994和 1997年被克隆鉴定[2 ,3] 。已知NGAL蛋白具有运输疏水性小分子 ,调节MMP 9活性等功能。近年来 ,随着NGAL蛋白在人体组织细胞中广泛分布情况的认证[4 ] ,特别是在一些肿瘤组织细胞中出现该基因异常过表达等事实的认识[5] ,有关N…  相似文献   

6.
早老蛋白(Presenilins)功能研究进展   总被引:2,自引:0,他引:2  
鲍云鹤  邹泉  郑坚瑜 《生命科学》2000,12(5):217-220
编码早老蛋白(Presenilins,PSs)的基因ps-1、ps-2被认为是构成早发家族性老年痴呆(early-onset familial Alzheimer’s disease,FAD)的主要致病基因。早老蛋白具有8个跨膜区的结构,在神经系统广泛表达。其功能尚未完全明确,最近几年的研究主要集中在早老蛋白与淀粉样沉淀前体蛋白(amyloid precursor protein,APP)的切割、  相似文献   

7.
莫永炎  姜勇  陈瑗 《生命的化学》2001,21(2):161-162
Alzheimer病 (AD)患者的神经病学特征是脑组织萎缩 ,出现大量的淀粉样斑块 (amyloidplaques ;亦称老年斑 ,senileplaques ,SP)和神经纤维缠结 (neu rofibritarytangles)沉积。AD病人痴呆的程度与淀粉样斑块的发展呈正相关。老年斑的主要成分是 β 淀粉样肽 ( β amyloidpeptide ,又称 β amyloidprotein ,Aβ) ,其分子量约为 4 .2kD ,由 39~ 4 3个氨基酸残基组成。Aβ来自一种跨膜糖蛋白———β 淀粉样质前体蛋白 (amyloid pr…  相似文献   

8.
脑啡肽酶(neprilysin)和阿尔茨海默病   总被引:2,自引:0,他引:2  
由于阿尔茨海默病 (Alzheimerdisease ,AD)的病因不明和到目前为止仍缺乏根治的办法 ,加之全世界范围的老龄化和AD的高发病率 ,一些科学家预言AD可能是本世纪最可怕的老年病。AD的数十年的漫长病程一般从 β淀粉样肽 (Aβ)在脑中沉着开始 ,Aβ是一个生理性多肽 ,它是淀粉样前体蛋白(APP)的水解产物。它的合成和分解代谢的平衡决定它在体内有一个稳定的水平。研究证明 ,由于基因突变导致的特殊形式的Aβ的产生增加 50 %就能引起AD ,Aβ代谢平衡的轻微改变不仅能影响AD的病理过程 ,而且能影响这个疾病的发…  相似文献   

9.
调节活化正常T细胞表达与分泌的趋化因子(regulateduponactivationnormalTcellexpressedandsecreted ,RANTES)为CC类趋化蛋白 ,具有多种不同的生物学功能。它不仅对多种细胞有趋化作用 ,还可以强烈的激活淋巴细胞 ,参与炎症反应的发生 ,调节细胞的生长和分化 ,参与HIV的感染。1.RANTES及其受体RANTES仅含 6 8个氨基酸残基 ,其来源广泛 ,NK细胞[1] 以及γδ T细胞[2 ] 均可组成性地表达RANTES ;炎症反应中CD8 T细胞、上皮细胞、成纤维细胞和血小…  相似文献   

10.
α-半乳糖苷酶   总被引:3,自引:0,他引:3  
最近各种媒体不断报道红血球类型可以通过酶处理进行转换 ,这对于输血和开拓血源有十分重要的意义 ,所用的酶是α 半乳糖苷酶。α 半乳糖苷酶 (α galactosidase ,α D galactosidegalactohydrolase ,EC 3.2 .1 .2 2 )能专一地催化α 半乳糖苷键的水解。它广泛存在于各种植物和动物体内 ,许多微生物如双歧杆菌 (Bifidobacterium)、黑曲霉菌 (Aspergillusniger) [1] 、大肠杆菌 (Escherichiacoli)K 1 2 1 [2 ]的抽提液中也发现有α 半乳糖苷酶的…  相似文献   

11.
Much emphasis has been placed on the middle ear region of reptiles and mammals as a taxonomic character. However, the anatomy of the middle ear region of birds has yet to be described adequately. The literature on the middle ear of birds is reviewed briefly and then the osteology and soft anatomy of the middle ear region of the skull are described for the families of the avian order Procellariiformes. Particular emphasis is paid to the foramina and paths of the nerves and blood vessels. Also discussed is the morphology of the basicranium and the quadrate. Comparative analyses of the characters are used to assess taxonomic conclusions.  相似文献   

12.
The Law of the Lifegivers: The Domestication of Desire. René Devisch and Claude Brodeur. Langhorne, PA: Harwood Academic Publishers, 1999. 268 pp.  相似文献   

13.
14.
Recent successes in functional brain imaging have suggested that the hippocampus is part of a novelty-detection network; but consideration of the available evidence and of the cognitive demands of novelty processing suggests that things are not so simple.  相似文献   

15.
The angioarchitecture of the toad's mesencephalon is studied by scanning electron microscopy of vascular corrosion casts. The arterial supply is performed by the superior mesencephalic artery and by an artery arising from the ramus posterior of the arteria carotis cerebralis just in front of the retroin-fundibular communicating artery. The venous drainage is exerted by the vena diencephalica, the vena lateralis mesencephalis and by anterior and posterior branches of the encephaloposthypophysial portal vein. Characteristics of the mesencephalic angioarchitecture are the centrifugal direction of the blood flow, the intensive capillarization, and the formation of vascular meshworks in the region of the stratum griseum periventriculare tecti and of the stratum griseum superficiale tecti.  相似文献   

16.
A study was made of the effect of ionizing radiation on the content and polypeptide composition of filamentous and soluble glial fibrillary acidic protein (GFAP) in different regions of rat brain. Ionizing radiation was shown to decrease considerably the level of soluble GFAP in cerebral cortex, cerebellum, middle brain and hippocampus. Polypeptide composition of soluble GFAP detected by the immunoblot method was found to be changed considerably in different brain areas of irradiated animals.  相似文献   

17.
18.
Dyes of all major types were tested for their suitability as the primary dye in the Gram stain. When a counterstain was not used, some dyes of all types were found to differentiate Gram-positive from Gram-negative organisms. When a counterstain was used, these dyes were found to vary greatly in their suitability. Those dyes found to be good substitutes for crystal violet were: Brilliant green, malachite green, basic fuchsin, ethyl violet, Hoffmann's violet, methyl violet B, and Victoria blue R. All are basic triphenylmethane dyes. Acid dyes were generally not suitable. Differences in the reaction of Gram-positive and Gram-negative cells to Gram staining without the use of iodine were observed and discussed but a practical differentiation could not be achieved in this manner. Certain broad aspects of the chemical mechanism of dyes in the gram stain are discussed.  相似文献   

19.
20.
The centromere is the region of the eukaryotic chromosome that determines kinetochore formation and sister chromatid cohesion. Centromeres interact with spindle microtubules to ensure chromatid segregation during mitosis and homologous chromosome segregation during meiosis I. In recent years, the overall organization of centromeres in several eukaryotic species has been described, yet the mechanisms of centromere definition remain elusive. Understanding the evolutionary origin of the centromere may well elucidate aspects of its function. With such intention, we hypothesize that centromeres were derived from telomeres during the evolution of the eukaryotic chromosome. We propose that the proto-eukaryotic cell could not have evolved a nucleus without concurrently evolving a new tubulin-based cytoskeleton, the microtubules, and a specific chromosomal region that enabled the chromosome-microtubule interaction, the centromere. The repetitive nature of the subtelomeric regions that gave rise to the centromeres forced the concerted evolution of the centromeres. Although this implies the absence of a conserved primary sequence, a conserved centromere-specific structural motif could still exist and determine where in the chromosome the centromere is to be formed.To support the “centromeres-from-telomeres” hypothesis, we discuss several situations, in meiosis and mitosis, where telomeric regions took over centromeric roles. The recently discovered phenomenon of centromere repositioning is also discussed because it has revealed new insights into how neocentromeres evolve.  相似文献   

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