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Uracil in the genome can result from misincorporation of dUTP instead of dTTP during DNA synthesis, and is primarily removed by uracil DNA glycosylase (UNG) during base excision repair. Telomeres contain long arrays of TTAGGG repeats and may be susceptible to uracil misincorporation. Using model telomeric DNA substrates, we showed that the position and number of uracil substitutions of thymine in telomeric DNA decreased recognition by the telomere single-strand binding protein, POT1. In primary mouse hematopoietic cells, uracil was detectable at telomeres, and UNG deficiency further increased uracil loads and led to abnormal telomere lengthening. In UNG-deficient cells, the frequencies of sister chromatid exchange and fragility in telomeres also significantly increased in the absence of telomerase. Thus, accumulation of uracil and/or UNG deficiency interferes with telomere maintenance, thereby underscoring the necessity of UNG-initiated base excision repair for the preservation of telomere integrity.  相似文献   

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亚硒酸钠对肝细胞L-02端粒酶活性和端粒长度的作用   总被引:3,自引:0,他引:3  
通过研究硒对端粒酶活性和端粒长度的作用 ,探讨硒抗衰老的生物学机制。实验以人肝细胞株L 0 2为研究对象 ,分别补充 0 .5和 2 .5 μmol L亚硒酸钠 ,采用端粒重复序列扩增 焦磷酸根酶联发光法、逆转录聚合酶链式反应法及流式荧光原位杂交法 ,分别检测细胞的端粒酶活性、人端粒酶逆转录酶催化亚基基因 (hTERT)的表达及端粒长度的变化。结果表明 :常规培养的肝细胞株L 0 2的端粒酶活性和hTERT基因表达水平均较低。补充 0 .5和2 .5 μmol L亚硒酸钠三周后细胞生长状况良好、端粒酶活性和hTERT基因表达水平显著性增高 ,且呈一定的剂量 效应关系。细胞补充亚硒酸钠四周后端粒长度显著增长。说明营养浓度的亚硒酸钠可通过提高端粒酶活性和增长端粒长度来减缓L 0 2肝细胞衰老、延长细胞寿命。  相似文献   

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目的:观察大剂量乙酰半胱氨酸(NAC)对高龄患者慢性阻塞性肺病(COPD)合并肺间质纤维化(PIF)急性加重期的干预作用,并对干预机制进行初步探讨。方法:年龄大于80岁COPD合并PIF患者18例,分为对照组(8例)和观察组(10例),对照组给予常规治疗,观察组在对照组治疗基础上给予口服乙酰半胱氨酸颗粒600 mg/次,3次/d,连用30天,观察两组治疗前后临床症状、肺功能指标(FVC、FEV1、FEV1/FVC)、动脉血氧分压(PaO2)、血液中细胞因子(IL-2和TNF-α)和影像学的变化。结果:观察组治疗总有效率和细菌培养转阴率显著升高(P<0.05);两组治疗后FVC、FEV1、FEV1/FVC、PaO2均较治疗前显著上升(P<0.05),血液中IL-2和TNF-α较治疗前显著下降(P<0.05);组间比较存在显著性差异(P<0.05);观察组治疗后胸部CT见感染明显控制。结论:在常规治疗基础上合用大剂量NAC可以有效治疗急性加重期COPD合并PIF的老年患者,机制可能与抑制炎性因子表达、减少细菌在呼吸道内的附着有关。  相似文献   

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Serum surfactant protein (SP)-A offers a useful clinical marker for interstitial lung disease (ILD). However, SP-A is occasionally elevated in non-ILD pulmonary patients. The present study was conducted to investigate factors that affect serum SP-A levels in respiratory medicine. Serum SP-A, serum SP-D, serum Klebs von den Lungen (KL)-6 and pulmonary function tests were evaluated in 929 patients (current smokers, n=255; ex-smokers, n=242; never-smokers, n=432) without ILD or pulmonary alveolar proteinosis. Serum SP-A was significantly higher in current smokers than in never- or ex-smokers (p<0.01 and p<0.05, respectively). Serum SP-A was significantly higher in chronic obstructive pulmonary disease (COPD) and pulmonary thromboembolism than in other diseases (p<0.01). Serum SP-A correlated positively with amount of smoking (p<0.01) and negatively with forced expiratory volume in 1 s/forced vital capacity (p<0.05). Serum SP-D and KL-6 were unaffected by smoking. Smoking should be taken into account when evaluating serum SP-A levels, and different baseline levels of serum SP-A should be established for smokers and non-smokers. Serum SP-A may also represent a useful marker for predicting COPD in the preclinical stage.  相似文献   

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动物体细胞重编程为诱导多能干细胞(iPS)是目前干细胞生物学研究的热点。文中重点对山羊体细胞重编程过程中端粒酶(TERT)基因的相对表达量进行了检测,探讨了山羊重编程细胞的形成与端粒酶基因表达的关系。从关中奶山羊胎儿皮肤分离得到的胎儿成纤维细胞(GEF),其增殖能力较强,核型正常(60条XY),通过转录因子在体外诱导得到山羊重编程细胞。利用Real-timeRT-PCR方法首先对关中奶山羊胎儿各种组织的TERT表达进行了检测,结果表明睾丸组织中TERT的表达显著高于上皮组织(P0.01),在山羊胎儿的其他组织中TERT也有不同程度的表达。对原代重编程细胞和4株不完全重编程细胞株的TERT表达检测结果发现,碱性磷酸酶(AP)阳性的重编程细胞端粒酶表达量要显著高于AP阴性的重编程细胞(P0.01)。这一结果揭示,激活端粒酶活性并使其保持较高的表达水平对体细胞的重编程至关重要。  相似文献   

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Abnormal inflammation and accelerated decline in lung function occur in patients with chronic obstructive pulmonary disease (COPD). Klotho, an anti-aging protein, has an anti-inflammatory function. However, the role of Klotho has never been investigated in COPD. The aim of this study is to investigate the possible role of Klotho by alveolar macrophages in airway inflammation in COPD. Klotho levels were assessed in the lung samples and peripheral blood mononuclear cells of non-smokers, smokers, and patients with COPD. The regulation of Klotho expression by cigarette smoke extract (CSE) was studied in vitro, and small interfering RNA (siRNA) and recombinant Klotho were employed to investigate the role of Klotho on CSE-induced inflammation. Klotho expression was reduced in alveolar macrophages in the lungs and peripheral blood mononuclear cells of COPD patients. CSE decreased Klotho expression and release from MH-S cells. Knockdown of endogenous Klotho augmented the expression of the inflammatory mediators, such as MMP-9, IL-6, and TNF-α, by MH-S cells. Exogenous Klotho inhibited the expression of CSE-induced inflammatory mediators. Furthermore, we showed that Klotho interacts with IκBα of the NF-κB pathway. Dexamethasone treatment increased the expression and release level of Klotho in MH-S cells. Our findings suggest that Klotho plays a role in sustained inflammation of the lungs, which in turn may have therapeutic implications in COPD.  相似文献   

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Persistent inflammation within the respiratory tract underlies the pathogenesis of numerous chronic pulmonary diseases including chronic obstructive pulmonary disease, asthma and pulmonary fibrosis. Chronic inflammation in the lung may arise from a combination of genetic susceptibility and environmental influences, including exposure to microbes, particles from the atmosphere, irritants, pollutants, allergens, and toxic molecules. To this end, an immediate, strong, and highly regulated inflammatory defense mechanism is needed for the successful maintenance of homeostasis within the respiratory system. Macroautophagy/autophagy plays an essential role in the inflammatory response of the lung to infection and stress. At baseline, autophagy may be critical for inhibiting spontaneous pulmonary inflammation and fundamental for the response of pulmonary leukocytes to infection; however, when not regulated, persistent or inefficient autophagy may be detrimental to lung epithelial cells, promoting lung injury. This perspective will discuss the role of autophagy in driving and regulating inflammatory responses of the lung in chronic lung diseases with a focus on potential avenues for therapeutic targeting.

Abbreviations AR allergic rhinitis

AM alveolar macrophage

ATG autophagy-related

CF cystic fibrosis

CFTR cystic fibrosis transmembrane conductance regulator

COPD chronic obstructive pulmonary disease

CS cigarette smoke

CSE cigarette smoke extract

DC dendritic cell

IH intermittent hypoxia

IPF idiopathic pulmonary fibrosis

ILD interstitial lung disease

MAP1LC3B microtubule associated protein 1 light chain 3 beta

MTB Mycobacterium tuberculosis

MTOR mechanistic target of rapamycin kinase

NET neutrophil extracellular traps

OSA obstructive sleep apnea

PAH pulmonary arterial hypertension

PH pulmonary hypertension

ROS reactive oxygen species

TGFB1 transforming growth factor beta 1

TNF tumor necrosis factor

  相似文献   

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目的:观察大剂量乙酰半胱氨酸(NAC)对高龄患者慢性阻塞性肺病(COPD)合并肺问质纤维化(PIF)急性加重期的干预作用,并对干预机制进行初步探讨。方法:年龄大于80岁COPD合并PIF患者18例,分为对照组(8例)和观察组(10例),对照组给予常规治疗,观察组在对照组治疗基础上给予口服乙酰半胱氨酸颗粒600mg/次,3次/d,连用30天,观察两组治疗前后临床症状、肺功能指标(FVC、FEV1、FEV1/FVC)、动脉血氧分压(PaO2)、血液中细胞因子(IL-2和TNF—α)和影像学的变化。结果:观察组治疗总有效率和细菌培养转阴率显著升高(P〈0.05);两组治疗后FVC、FEV1、FEV1/FVC、PaO2均较治疗前显著上升(P〈0.05),血液中IL-2和TNF—α较治疗前显著下降(P〈0.05);组间比较存在显著性差异(P〈0.05);观察组治疗后胸部CT见感染明显控制。结论:在常规治疗基础上合用大剂量NAC可以有效治疗急性加重期COPD合并PIF的老年患者,机制可能与抑制炎性因子表达、减少细菌在呼吸道内的附着有关。  相似文献   

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A novel series of formoterol–phthalazinone hybrids were synthesised and evaluated as dual pharmacology β2-adrenoceptor agonists and PDE4 inhibitors. Most of the hybrids displayed high β2-adrenoceptor agonist and moderate PDE4 inhibitory activities. The most potent compound, (R,R)-11c, exhibited agonist (EC50 = 1.05 nM, pEC50 = 9.0) and potent PDE4B2 inhibitory activities (IC50 = 0.092 μM).  相似文献   

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A large body of evidence indicates that chronic obstructive pulmonary disorder (COPD) is accompanied by oxidative stress and inflammatory and genetic pathways. Epidemiological studies indicate that COPD is a major cause of mortality and morbidity in the world. Recent research development in COPD focuses on accelerated aging and various oxidative stress biomarkers. It involves the clinical manifestation of the disease process and may also contain biochemical, immunological, physiological, morphological, and genetic aspects that add to the progressiveness of the disease. Herein, we summarize findings that highlight the role of dimensions of COPD in the investigation of oxidative stress, inflammatory responses, genetic and epigenetic studies, and pharmacological and dietary antioxidant intervention.  相似文献   

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Microarrays are a powerful tool that have multiple applications both in clinical and cell biology arenas of common lung diseases. To exemplify how this tool can be useful, in this review, we will provide an overview of the application of microarray technology in research relevant to common lung diseases and present some of the future perspectives.  相似文献   

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Senescence of alveolar type 2 (ATII) cells, progenitors of the alveolar epithelium, is implicated in the pathogeneses of idiopathic pulmonary fibrosis (IPF), an aging‐related progressive fatal lung disorder with unknown etiology. The mechanism underlying ATII cell senescence in fibrotic lung diseases, however, remains poorly understood. In this study, we report that ATII cells in IPF lungs express higher levels of serpine 1, also known as plasminogen activator inhibitor 1 (PAI‐1), and cell senescence markers p21 and p16, compared to ATII cells in control lungs. Silencing PAI‐1 or inhibition of PAI‐1 activity in cultured rat ATII (L2) cells leads to decreases in p53 serine 18 phosphorylation (p53S18P), p53 and p21 protein expressions; an increase in retinoblastoma protein phosphorylation (ppRb); and a reduction in the sensitivity to bleomycin‐ and doxorubicin‐induced senescence. Silencing p53, on the other hand, abrogates PAI‐1 protein‐stimulated p21 expression and cell senescence. In vivo studies, using ATII cell‐specific PAI‐1 conditional knockout mouse model generated recently in this laboratory, further support the role of PAI‐1 in the activation of p53‐p21‐Rb cell cycle repression pathway, ATII cell senescence, and lung fibrosis induced by bleomycin. This study reveals a novel function of PAI‐1 in regulation of cell cycle and suggests that elevation of PAI‐1 contributes importantly to ATII cell senescence in fibrotic lung diseases.  相似文献   

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A detailed analysis has been carried out of the correlation between the signals detected by MRI in the rat lung after allergen or endotoxin challenge and parameters of inflammation determined in the broncho-alveolar lavage (BAL) fluid. MRI signals after allergen correlated highly significantly with the BAL fluid eosinophil number, eosinophil peroxidase activity and protein concentration. Similar highly significant correlations were seen when the anti-inflammatory glucocorticosteroid, budesonide, manifested against allergen. In contrast, following endotoxin challenge, mucus was the sole BAL fluid parameter that correlated significantly with the long lasting signal detected by MRI. Since edema is an integral component of pulmonary inflammation, MRI provides a noninvasive means of monitoring the course of the inflammatory response and should prove invaluable in profiling anti-inflammatory drugs in vivo. Further, the prospect of noninvasively detecting a sustained mucus hypersecretory phenotype in the lung brings an important new perspective to models of chronic obstructive pulmonary diseases.  相似文献   

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