The emerging role of epigenetics in cellular and organismal aging

Genome modifications resulting from epigenetic changes appear to play a critical role in the development and/or progression of cancer. Scatter experimental evidence suggests that epigenetic changes could also be critical determinants of cellular senescence and organismal aging. Here we review the current evidence and discuss how imbalances in chromatin remodelers might trigger irreversible growth arrest in proliferating cells and tissues. Experimental data using drugs that target specific chromatin remodeling enzymes suggest that such approach could lead to the development of novel therapeutic modalities for the prevention or amelioration of some age-related dysfunctions.     

单倍相合异基因骨髓移植前后骨髓像分析

目的观察单倍相合异基因骨髓移植前后骨髓像、造血能否重建。方法对22例患者造血干细胞移植前骨髓穿刺抽吸涂片镜检;骨髓移植成功出层流室首次骨髓穿刺抽吸涂片;每月定期复查骨髓穿刺抽吸涂片镜栓。同时观察外周血涂片和骨髓涂片2张或2张以上。结果22例患者单倍相合并基因造血干细胞移植后骨髓像全部达到正常,完全缓解。移植成功随访,其中6例患者随访中骨髓细胞出现少许病态造血现象,2例出现纯红细胞性再生障碍性贫血（PRCA）,余14例骨髓正常。结论单倍相合并基因骨髓移植能够使白血病和重型再障骨髓重建。造血重建恢复期可能继发骨髓增生异常综合症（MDS）和PRCA。     

肿瘤发生的表观遗传学:进展与临床意义

表观遗传(epigenetics)指所有不通过DNA序列改变就能影响基因表达(从而决定细胞乃至个体表型)的、可遗传的(即可伴随细胞分裂传递下去)调控方式,包括DNA甲基化、组蛋白修饰、染色质重塑、miRNA、朊病毒等。表观遗传调控在干细胞自我更新、定向分化、器官发育等生命过程中起着至关重要的作用:每一个多细胞生物个体都是由一个受精     

中医药联合高效抗逆转录病毒疗法对艾滋病患者免疫重建作用影响的研究

目的:探讨中医药联合高效抗逆转录病毒疗法(HAART)对艾滋病患者的免疫重建作用.方法:通过对近5a来中医药联合HARRT治疗艾滋病患者及其对患者免疫重建相关研究报道的分析,了解中医药联合HAART对艾滋病患者的免疫重建作用.结果:中医药联合HAART对艾滋病患者具有较好的免疫重建作用,较单纯HAART治疗具有明显的优势.结论:中医药联合HAART对艾滋病患者有免疫重建作用.     

人脐血CD34~+细胞在NOD/SCID小鼠体内重建体液免疫的实验研究

目的探讨人脐血CD34+造血干细胞(HSC)在NOD/SCID小鼠模型体内体液免疫功能重建的作用。方法从新鲜脐血中分离出单个核细胞(MNC),利用免疫磁珠分选法筛选CD34+造血干细胞,经尾静脉输注入经亚致死剂量照射的NOD/SCID小鼠体内,移植后4、6、8、10周分批处死存活的小鼠,取其脾脏和外周血,分别进行细胞表型分析、体液免疫分析,监测小鼠体液免疫功能重建情况。结果照射2周后,阴性对照组小鼠全部死亡,6周后移植组小鼠存活率为37.5%,空白对照组小鼠存活率为100%。移植4、6、8、10周移植组外周血人CD45+细胞表达(%)分别为4.87±1.23、9.22±2.07、12.34±2.38、8.14±2.36,CD19+B淋巴细胞表达(%)分别为1.07±0.50、2.17±0.95、3.34±0.90、1.67±0.90。移植后10周,在移植组小鼠脾脏可见CD19+B淋巴细胞分布。结论经照射后的NOD/SCID小鼠通过人脐血CD34+细胞植入可建立起人鼠嵌合免疫模型。缺少相应细胞因子刺激,CD34+细胞分化能力随时间减弱。     

The COX-2 gene promoter polymorphism -765 delays CD4 T-cell reconstitution after lymphocyte depletion with antithymocyte globulins

Polyclonal antithymocyte globulins (ATG) induce persistent changes in T-lymphocyte subsets characterized by low CD4 T. The mechanisms remain partly unknown. Prostaglandin E(2) (PGE(2)) is involved in lymphocyte homeostasis. Whether PGE(2) may be involved in persistent CD4 T-cell lymphopenia after ATG is unknown. We examined the association between this polymorphism and CD4 T-cell count in 159 renal transplant recipients (RTR) who received ATG. Analysis of these patients identified 6 CC (3.8%), 32 GC (22.6%), and 117 GG (73.6%) genotypes. Patients with the GG genotype had significantly higher serum PGE(2) concentrations, leading us to compare C carriers with GG patients. Carriers of the C allele had lower CD4 T cell count 1 year (235 ± 96 vs 323 ± 227/mm(3); p = 0.022) and 2 years posttransplant (325 ± 79 vs 422 ± 231/mm(3); p = 0.024). In multivariate analysis, the C allele (p = 0.029) conferred an increased risk of posttransplant CD4 T-cell lymphocytopenia. Pretransplant T-cell receptor excision circle levels were lower in C carriers. COX-2 gene promoter polymorphism at position -765 (G → C) is associated with persistent CD4 T-cell lymphopenia after ATG in RTR. This effect is likely to be mediated by the actions of PGE(2) on thymus function and viability.     

Epigenetic modifications induced by early enrichment are associated with changes in timing of induction of BDNF expression

During early postnatal phase, the environment deeply affects developmental trajectories through epigenetic mechanisms that control the levels of key molecules for brain function, such as neurotrophins. Indeed, it has been shown that adverse early experiences induce epigenetic modifications leading to decreased brain derived neurotrophic factor (BDNF) levels at adulthood. However, no data about the effects of enriching early experiences are available. Here we exploit the mouse Communal Nest (CN) paradigm in order to investigate the effects of a highly stimulating early social environment on BDNF epigenetic modifications and protein expression at adulthood. CN, which consists of a single nest where three mothers keep their pups together and share care-giving behavior until weaning, is characterized by high levels of maternal behavior and peer interactions. Our results show that CN leads to high levels of histone acetylation at the BDNF gene at adulthood, which is more permissive to expression. However, such epigenetic modification is associated to increased BDNF protein expression only 1 h after an environmental challenge and not at baseline or 3 h after the challenge, suggesting that the epigenetic modifications do not affect expression under steady-state conditions but allow a fast increase in BDNF levels following stimulation. The present findings corroborate the role of epigenetic modifications in mediating the effects of the early social environment on adult brain function and behavior. In addition, these show, for the first time, an association between an epigenetic modification and a change in the rapidity of induction of protein expression, expanding the knowledge on the mechanisms by which epigenetic changes modify brain function.     

卡维地洛对慢性心力衰竭左室重塑及心功能的影响

目的探讨卡维地洛对慢性心力衰竭左室重塑及心功能的影响。方法将68例慢性心衰患者,随机分为两组,常规抗心衰药物治疗者为对照组,在此基础上加用卡维地洛治疗者为治疗组。卡维地洛从小剂量开始,根据血压、心率逐渐加大剂量,疗程6个月。观察治疗前后的左室射血分数,左室舒张末期内径,左室收缩末期内径及心率变化。结果在常规治疗基础上加用卡维地洛可改善左室重塑及心功能。结论慢性充血性心力衰竭(CHF),是以肾素——血管紧张素系统(RAAS)交感神经系统(SNS)过度激活,心室功能恶化及心室重塑为特征的综合征。大量实验证实,β受体阻滞剂对CHF有治疗作用,可改善临床症状,增加运动耐量,降低病死率。     

Mechanisms that regulate localization of a DNA double-strand break to the nuclear periphery

DNA double-strand breaks (DSBs) are among the most deleterious forms of DNA lesions in cells. Here we induced site-specific DSBs in yeast cells and monitored chromatin dynamics surrounding the DSB using Chromosome Conformation Capture (3C). We find that formation of a DSB within G1 cells is not sufficient to alter chromosome dynamics. However, DSBs formed within an asynchronous cell population result in large decreases in both intra- and interchromosomal interactions. Using live cell microscopy, we find that changes in chromosome dynamics correlate with relocalization of the DSB to the nuclear periphery. Sequestration to the periphery requires the nuclear envelope protein, Mps3p, and Mps3p-dependent tethering delays recombinational repair of a DSB and enhances gross chromosomal rearrangements. Furthermore, we show that components of the telomerase machinery are recruited to a DSB and that telomerase recruitment is required for its peripheral localization. Based on these findings, we propose that sequestration of unrepaired or slowly repaired DSBs to the nuclear periphery reflects a competition between alternative repair pathways.