The association between telomere length (TL) in peripheral blood cells and cancer risk remains inconclusive. We carried out a meta-analysis on prospective studies. The study-specific RR estimates were first transformed to a common comparable scale and then were pooled by a random-effects model. The dataset was composed of 13,894 cases and 71,672 controls from 28 studies in 25 articles. In the comparison of the longest versus shortest third of TL, we observed a marginally positive association between longer TL and higher risk of total cancers [OR = 1.086; 95% confidence interval (CI), 0.952-1.238]. Subgroup analyses showed that the association was stronger in lung cancer ( = 3; OR = 1.690; 95% CI, 1.253-2.280), in men ( = 6; OR = 1.302; 95% CI, 1.120-1.514) and in studies with more precise methods for DNA extraction (phenol-chloroform, salting-out or magnetic bead, = 6, OR = 1.618; 95% CI, 1.320-1.985) and TL measurement (multiplex Q-PCR, = 8; OR = 1.439; 95% CI, 1.118-1.852). Our meta-analysis suggested longer TL in peripheral blood cells is a likely risk factor for lung cancer or cancers in men. Accurate DNA extraction and TL measurement methods make it more liable to find significant associations between TL and cancer risk and thus should be taken into consideration in future epidemiologic studies. .

Obesity amplifies the association of long-term air pollution exposure with blood pressure and hypertension in Chinese children.

BackgroundMicroRNA-21 (miR-21) has been suggested to play a significant role in the prognosis of carcinoma. The recognition of novel biomarkers for the prediction of cancer outcomes is urgently required. However, the potential prognostic value of miR-21 in various types of human malignancy remains controversial. The present meta-analysis summarises and analyses the associations between miR-21 status and overall survival (OS) in a variety of tumours.MethodsEligible published studies were identified by searching the PubMed and Chinese Biomedicine databases. The patients’ clinical characteristics and survival results were pooled, and a pooled hazard ratio (HR) with 95% confidence intervals (95% CI) was used to calculate the strength of this association. A random-effects model was adopted, and then, meta-regression and subgroup analyses were performed. In addition, an analysis of publication bias was also conducted.ResultsTwenty-seven eligible articles (including 31 studies) were identified that included survival data for 3273 patients. The pooled HR suggested that high miR-21 was clearly related to worse overall survival (HR = 2.27, 95% CI: 1.81-2.86), with a heterogeneity measure index of I2 = 76.0%, p = 0.001, showing that miR-21 might be a considerable prognostic factor for poor survival in cancer patients.ConclusionsMiR-21 might be a potentially useful biomarker for predicting cancer prognosis in future clinical applications.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-819) contains supplementary material, which is available to authorized users.

Background Studies in developed countries have reported that the prevalence of asthma and rhinitis is higher in urban areas than in rural areas, and this phenomenon is associated with urbanization and changing indoor microbiome exposure. Developing countries such as China have experienced rapid urbanization in past years, but no study has investigated microbiome exposure and urban-rural health effects in these countries. Methods Nine high schools from urban and rural areas were randomly selected in Shanxi Province, China, and classroom vacuum dust was collected for shotgun metagenomic sequencing. A self-administered questionnaire was collected from 1332 students for personal information and health data. Three-level logistic regression was performed between microbial richness/abundance/functional pathways and the occurrence of asthma and rhinitis symptoms. Results Consistent with developed countries, the prevalence of wheeze and rhinitis was higher in urban areas than in rural areas (p < 0.05). Metagenomic profiling revealed 8302 bacterial, 395 archaeal, 744 fungal, 524 protist and 1103 viral species in classroom dust. Actinobacteria (mean relative abundance 49.7%), Gammaproteobacteria (18.4%) and Alphaproteobacteria (10.0%) were the most abundant bacterial classes. The overall microbiome composition was significantly different between urban and rural schools (p = 0.001, Adonis). Species from Betaproteobactera, Gammaproteobacteria and Bacilli were enriched in urban schools, and species from Actinobacteria and Cyanobacteria were enriched in rural schools. Potential pathogens were present in higher abundance in urban schools than in rural schools (p < 0.05). Pseudoalteromonas, Neospora caninum and Microbacterium foliorum were positively associated with the occurrence of wheeze, rhinitis and rhinoconjunctivitis, and Brachybacterium was protectively (negatively) associated with rhinitis (p < 0.01). The abundance of human endocrine and metabolic disease pathways was positively associated with rhinitis (p = 0.008), and butyrate and propionate metabolic genes and pathways were significantly enriched in rural schools (p < 0.005), in line with previous findings that these short-chain fatty acids protect against inflammatory diseases in the human gut. Conclusions We conducted the first indoor microbiome survey in urban/rural environments with shotgun metagenomics, and the results revealed high-resolution microbial taxonomic and functional profiling and potential health effects.

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