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1.
雌性多能干细胞(iPS细胞)多能性状态的获得伴随着X染色体的表观修饰重编程。分化终末状态的雌性体细胞中有1条X染色体发生异染色质化而导致其失活。在体细胞诱导多能性干细胞的过程中,失活的X染色体重新活化。在重编程过程中,多能因子和X染色体失活中心的非编码基因的联系紧密。文章主要从分子水平上讨论多能干细胞X染色体表观修饰的相关研究进展。小鼠胚胎干细胞(ES细胞)是标准的多能性基态。X染色体上非编码RNA的表达可能是一个评价iP S表观遗传状态的标记,相关研究可以为细胞治疗的临床应用提供重要依据。 相似文献
2.
细胞核移植技术细胞核移植技术 ,根据核供体细胞的不同 ,有胚胎细胞核移植、胚胎干细胞核移植、胎儿成纤维细胞核移植和体细胞核移植。以核移植为核心技术的动物克隆技术 ,其基本技术环节除基本显微操作外 ,主要包括供核的分离、受体细胞的去核、核卵重组、重组胚的融合、核移植胚的培养与移植或重复克隆。供体核的分离胚胎细胞用 0 2 %链霉蛋白酶预处理胚胎 ,去胚胎的胶膜及透明带 ,离出单个卵裂球。目前在胚细胞核分离技术中有两大重要进展 :①胚胎干细胞系建立──胚胎干细胞在发育阶段上类似于内细胞团细胞 ,胚胎干细胞系是早期胚胎经… 相似文献
3.
近年来,胚胎干细胞的应用越来越广泛,在体外将小鼠胚胎干细胞诱导分化为肌肉细胞,并且利用这些分化得来的肌肉细胞治疗肌肉退行性疾病,一直是胚胎干细胞研究领域的热点,而胚胎干细胞的分化机制更是其中的难点。目前,用于诱导小鼠胚胎干细胞分化为骨骼肌细胞的方法很多,但分化的效率并不是很高,所以研究胚胎干细胞向骨骼肌细胞方向分化的机制显得尤为重要。文章仅就最近几年对小鼠胚胎干细胞向骨骼肌细胞方向分化的一些方法及其机制作一综述。 相似文献
4.
胚胎干细胞ES是从早期胚胎或原始生殖细胞中分离出来的能够在体外进行传代培养,而不分化的全能性细胞,ES细胞最主要的生物学特征是具有发育的全能性或多能性,ES细胞能在体外培养、增殖、传代、冻存和诱导分化,是研究生物发育、行为和建立人体疾病模型的理想工具,本文重点论述了影响胚胎干细胞分离和克隆的因素。并展望了胚胎干细胞的应用前景。 相似文献
5.
自我更新、全能的胚胎干(ES)细胞可为移植提供几乎无限的供体来源。现已设计了一种可以在体外生成来自ES细胞的少突胶质细胞和星形胶质细胞前体,在人髓鞘质病的大鼠模型上进行的移植表明ES细胞源的前体同宿主神经元相互作用,在大脑和脊髓轴突作用更为明显。因此,ES细胞可为神经移植提供一种有价值的特异性体细胞前体的来源。源于囊胚阶段的内细胞群的ES细胞是全能干细胞,它们能分化为所有组织和细胞类型。最近的发现扩展了ES细胞的潜在作用,包括从人胚胎组织中分离出ES细胞,在绵羊和小鼠成体组织中将细胞核移入去核卵细胞,可产生同一… 相似文献
6.
胚胎干细胞是从动物胚胎内细胞团或原始生殖细胞分离的具有全能性的细胞，在遗传学、发育生物学和细胞工程领域具有广阔的应用前景。抑制胚胎干细胞分化和促进胚胎干细胞增殖是克隆胚胎干细胞的关键，本文介绍了饲养层、条件培养基、分化抑制因子对哺乳动物胚胎干细胞分离与克隆的影响，并探讨了白血病抑制因子影响胚胎干细胞克隆的机理，认为在饲养层中添加分化抑制因子能有效提高胚胎干细胞克隆率。 相似文献
7.
胚胎干细胞包括来自囊胚内细胞群的ES细胞和来自胚胎原始生殖嵴的EG细胞,其中ES细胞维持不分化传代培养已达80代。由于这些细胞具有高度复制能力及多向性分化潜能,近年来的研究使人们对胚胎干细胞的培养条件、诱导分化及其应用前景,以及当前研究方面存在的主要问题有了进一步的认识。 相似文献
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胚胎干细胞(embryonic stem cell,ES细胞)主要来自于胚胎发育早期囊胚中内细胞群(i nner cel l mas s,I CM),具有无限增殖、自我更新和多向分化的特性。理论上可以诱导分化为机体中200多种细胞,可作为细胞移植、组织替代,甚至器官克隆的细胞供体,为将来治疗人类诸多难治性疾病提供细胞来源。本文简述了胚胎干细胞的诱导分化方法、定向分化的一些细胞种类以及其应用前景。 相似文献
9.
神经干细胞是神经系统内保持持续增值和分化能力的细胞，目前对神经干细胞的来源、分布、增殖、分化都有较清楚的认识，但是还有许多问题有待解决。研究表明神经干细胞在治疗多种神经系统疾病方面有很大的应用价值，细胞移植是神经干细胞在临床应用中的一个十分有效的途径。 相似文献
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诱导多潜能干细胞(induced pluripotent stem cells,i PS)是指通过在分化的体细胞中表达特定的转录因子来诱导其发生重编程而获得的可不断自我更新和具有多向分化潜能的细胞。诱导多潜能干细胞在生物医学领域具有重要的应用前景。而物种的大小以及解剖学和生理学特性决定了其是否适合用作临床模型。2009年,3个不同的研究小组几乎同时发表了获得猪诱导多潜能干细胞的文章。研究人员通过逆转录病毒载体将4个重编程因子(POU5F1,SOX2,c MYC和KLF4)导入体细胞,诱导产生具有胚胎干细胞(embryonic stem cells,ES)特性的诱导多潜能干细胞。研究发现,猪诱导多潜能干细胞比鼠诱导多潜能干细胞更接近人胚胎干细胞和人诱导多潜能干细胞。假如可以建立特定的猪诱导多潜能干细胞诱导分化为特定的细胞系,那么就有可能通过这些动物去检测诱导多潜能干细胞在基因治疗中的安全性和有效性。 相似文献
11.
In late December 1983, 2 800 veterinarians across Canada were sent a questionnaire in order to assess the status of heartworm disease in Canada in 1983 and 26% of them responded. Veterinarians reported that 59 504 dogs were blood-tested to check for microfilariae and 771 dogs (1.30% of those tested) were found with Dirofilaria immitis. Heartworm disease was diagnosed in all provinces except New Brunswick and Newfoundland but most (733) of the cases were in Ontario. Heartworm disease was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 31% of the cases were observed with clinical signs of heartworm disease and 64% had a history of not having left Canada. Southwestern Ontario continues to be the focus of the infection and most of the dogs there had not left the province previously. 相似文献
13.
In late December 1985, 1485 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1985 and 44% of them responded. Veterinarians reported that 137,300 dogs were blood-tested to check for microfilariae and 1210 dogs were found with heartworm. Another 36 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number diagnosed in 1985 as 1247 (0.91%). Heartworm was reported from all provinces except Prince Edward Island, Newfoundland and Saskatchewan but most (1126) of the cases were in Ontario. Southwestern Ontario continued to be the primary focus of the infection in Canada. From Quebec, 91 cases were reported mostly from and around Montreal. From Manitoba, 19 cases were reported from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 28% of the cases were observed with clinical signs of heartworm disease and 78% had a history of not having left Canada. 相似文献
14.
In late November 1988, 1581 small and mixed animal clinics and institutional veterinarians across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1988, and 46% of them responded. Veterinarians reported that 181,577 dogs were blood-tested for heartworm disease and 367 dogs were found with D. immitis microfilariae. Another 60 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1988 as 441 (0.24%). 相似文献
15.
In late December 1984, 1853 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1984 and 35% of them responded. Veterinarians reported that 97,794 dogs were blood-tested to check for microfilariae and 1417 dogs (1.45% of those tested) were found with heartworm. Another 34 dogs were amicrofilaremic, but were diagnosed as having heartworm disease, to give the total number diagnosed in 1984 as 1451 (1.48%). Heartworm was reported from all provinces except Prince Edward Island and Newfoundland but most (1310) of the cases were in Ontario. In Quebec, 126 cases were reported mostly from west of Montreal. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 27% of the cases were observed with clinical signs of heartworm disease and 72% had a history of not having left Canada. Southwestern Ontario continued to be the primary focus of the infection. 相似文献
17.
In late November 1991, 1883 clinics in Canada were sent a questionnaire to assess the status of Dirofilaria immitis in dogs in 1991 and there was a 60.0% response. There were 344,031 dogs tested for heart-worm (HW), 627 were found infected and the prevalence of HW infection was 0.18%. There were 417 dogs with HW in Ontario, 116 in Manitoba, 38 in Quebec, 53 in British Columbia, three in Alberta, and one in Nova Scotia. In British Columbia, all of the infected dogs but one were from the Okanagan valley which, as from 1991, is a new focus of infection in Canada. Most dogs with HW had not been on preventive medication in 1990, and the prevalence among dogs tested and unprotected was 0.59%. That prevalence was considerably higher in endemic areas. Companion dogs, over three years of age and maintained primarily outdoors in rural areas, were most frequently infected. One cat was diagnosed with D. immitis and 33 dogs had Dipetalonema reconditium. 相似文献
18.
In late November 1989, 1732 clinics and institutional veterinarians were sent a questionnaire to assess the status of Dirofilaria immitis, and 51.7% responded. Of 247,716 dogs tested, 394 had D. immitis microfilariae and 51 were amicrofilaremic for a total of 445 cases and heartworm prevalence of 0.17%. Most (408) of these dogs had no preventive medication and the prevalence among dogs tested and unprotected was 1.01%. That prevalence was considerably higher in endemic areas. Thirty-seven dogs with heartworm had preventive medication. Heartworm was most frequent in companion dogs over three years of age maintained outdoors in rural areas. About 75% of the cases had never left Canada, 26% had clinical signs and 125 were not treated. Heartworm was reported from British Columbia, Manitoba, Ontario, Quebec, Nova Scotia and Newfoundland, but 383 cases were in Ontario. South-western Ontario was the primary focus of infection. There were 33 cases in Quebec and 24 in Manitoba, mainly found in and around Metropolitan Montreal and Winnipeg respectively. 相似文献
19.
In late November 1987, 1246 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1987, and 50% of them responded. Veterinarians reported that 165,428 dogs were blood tested for heartworm disease and 511 dogs were found with D. immitis microfilariae. Another 78 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1987 as 589 (0.35%). 相似文献
20.
In late December 1986, 1224 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1986; 46% of them responded. Veterinarians reported that 150,989 dogs were blood-tested for microfilariae and 869 dogs were found with heartworm. Another 65 dogs were amicrofilaremic but diagnosed with heartworm disease and one was found with heartworm at necropsy to give the total number diagnosed in 1986 as 935 (0.62%). Heartworm was reported from Manitoba, New Brunswick, Ontario and Quebec, but most (810) of the cases were from Ontario. South-western Ontario continued to be the primary focus of the infection in Canada. There were 103 cases reported from Quebec, mostly from and around Montreal, and 21 cases from Manitoba, from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 33% of the cases were observed with clinical signs of heartworm disease and 81% had a history of not having left Canada. 相似文献
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